HYDRAULIC DOOR CLOSER WITH FLUID OVERFLOW CHAMBER

Abstract

This disclosure is generally directed to a hydraulic door closer, and more specifically is directed to a hydraulic storm or screen door closer that has a fluid overflow chamber providing fluid volume and pressure control for both expanded and contracted fluid at different temperatures. The disclosed hydraulic door closer comprises a fluid overflow chamber adapted to hold sufficient fluid to maintain required operating fluid or oil levels at different temperatures, and to ensure proper closer performance under both extreme high and low temperature conditions.

Claims

1. A door closer comprising fluid in a housing fitted with: a biasing spring in operative communication with a closer piston, and a vertical hydraulic fluid overflow chamber comprising an overflow chamber piston, wherein the overflow chamber piston is biased when the hydraulic fluid is in an expanded state.

Description

DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 is an isometric view of a rotational hydraulic closer.

[0012] FIG. 2 is a side view of the closer defining the cross section for FIG. 3A.

[0013] FIG. 3A is a cross-sectional top view of the closer as defined by FIG. 2.

[0014] FIG. 3B is a cross-sectional top view of an alternative embodiment of the closer as defined by FIG. 2.

[0015] FIG. 3C is a cross-sectional top close up view of the alternative embodiment as defined by FIG. 3B.

[0016] FIG. 4 is a side view of the closer defining the cross section for FIG. 5.

[0017] FIG. 5 is a cross-sectional front view of the closer as defined by FIG. 4.

[0018] FIG. 6 is a front view of the closer defining the cross section for FIG. 7.

[0019] FIG. 7 is a cross-sectional side view of the closer as defined by FIG. 6.

[0020] FIG. 8 is a side view of the closer defining the cross section for FIG. 9A.

[0021] FIG. 9A is a cross-sectional front view of the closer as defined by FIG. 8, which shows an overflow chamber in a horizontal orientation.

[0022] FIG. 9B is a cross-sectional front view of an alternate embodiment of the closer as defined by FIG. 8, in which the flow of oil from the pressurized side of the piston to the unpressurized side of the piston is regulated by an alternate type of device.

[0023] FIG. 9C is a cross-sectional front view of the another alternate embodiment of the closer as defined by FIG. 8, where the oil is regulated by a speed control device located in the piston to control the flow of oil from the pressurized side of the piston through the piston to the unpressurized side of the piston.

[0024] FIG. 10 is a side view of the closer defining the cross section for FIG. 11.

[0025] FIG. 11 is a cross-sectional front view of the closer as defined by FIG. 10, which shows an overflow chamber in a vertical orientation.

[0026] FIG. 12 is a side view of the closer defining the cross section for FIG. 13.

[0027] FIG. 13 is a cross-sectional front view of the closer as defined by FIG. 12, which shows an overflow chamber in an angular orientation.

[0028] FIGS. 14, 14A, 14B and 14C illustrate a horizontal fluid chamber containing an overflow chamber piston, overflow chamber piston seal, and overflow chamber spring.

[0029] FIG. 15 is a side view of the closer defining the cross section for FIG. 16.

[0030] FIG. 16 is a cross-sectional front view of the closer as defined by FIG. 15 which shows an overflow chamber in a horizontal orientation in the interior region of the closer defined by the biasing spring.

[0031] FIGS. 17, 17A, 17B and 17C illustrate a horizontal fluid chamber containing a closely fitted overflow chamber piston, and overflow chamber spring.

[0032] FIGS. 18, 18A, 18B and 18C illustrate a horizontal fluid chamber containing a closely fitted overflow chamber piston.

[0033] FIGS. 19, 19A, 19B and 19C illustrate a horizontal fluid chamber containing a multi-durometer overflow chamber piston, and overflow chamber spring.

[0034] FIGS. 20, 20A, 20B and 20C illustrate a horizontal fluid chamber containing a multi-durometer overflow chamber piston.

[0035] FIG. 21 is a side view of the closer defining the cross section for FIG. 22.

[0036] FIG. 22 is a cross-sectional front view of the closer as defined by FIG. 21, which shows a static overflow chamber in a vertical orientation above a biasing spring.

[0037] FIG. 23 is a side view of the closer defining the cross section for FIG. 24.

[0038] FIG. 24 is a cross-sectional front view of the closer as defined by FIG. 23, which shows a gravity-operated overflow chamber in a vertical orientation above a biasing spring.

[0039] FIG. 25 is a more detailed view of an example of the gravity operated overflow chamber piston of FIG. 24, where the gravity-operated piston is closely fitted to the overflow chamber.

[0040] FIG. 26 is a more detailed view of another example of the gravity operated overflow chamber piston of FIG. 24, where the gravity-operated piston includes a piston seal.

[0041] FIG. 27 is a more detailed view of yet another example of the gravity operated overflow chamber piston of FIG. 24, where the gravity-operated piston is a multi-durometer piston with a seal component of a second durometer that is integral to the gravity-operated piston.

[0042] In the listed figures, the described components have the reference numerals set out in the following table:

TABLE-US-00001 Component Feature Description 100 Rotational Hydraulic Closer 110 Pinion 112 Pinion gear teeth 120 Housing 121 Overflow connecting chamber 123 Horizontal overflow chamber 124 Vertical overflow chamber 125 Angular overflow chamber 126 Gravity-operated overflow chamber 127 Static overflow chamber 128 Overflow chamber internal volume 129 Overflow chamber 130 Gravity-operated piston 131 Gravity-operated piston 132 Gravity-operated piston 133 Sealing portion 135 Seal 140 Overflow chamber vertical plug 183 Horizontal overflow chamber screw plug 184 Vertical overflow chamber screw plug 185 Angular overflow chamber screw plug 186 Overflow chamber screw plug 187 Overflow chamber top 190 Closer piston 192 Piston gear teeth 193 Piston Seal 194 Sealing portion of closer piston 200 Mounting tab 210 Biasing spring 220 Valve, speed control 225 Speed control device 226 Speed control device 230 Pressurized side of piston 240 Unpressurized side of piston 250 Speed control chamber 260 Vertical speed control chamber plug 270 Horizontal speed control chamber plug 280 Overflow chamber piston 281 Overflow chamber piston seal 282 Overflow chamber spring 323 Horizontal overflow chamber 380 Overflow chamber piston 382 Overflow chamber spring 423 Horizontal overflow chamber 480 Overflow chamber piston 482 Overflow chamber compressible fluid 523 Horizontal overflow chamber 580 First portion of overflow chamber piston 581 Second portion of overflow chamber piston 582 Overflow chamber spring 623 Horizontal overflow chamber 680 Overflow chamber piston 681 Overflow chamber piston sealing portion 682 Overflow chamber compressible fluid

DETAILED DESCRIPTION OF THE INVENTION

[0043] The disclosed hydraulic door closer having an overflow chamber or reservoir is particularly intended for use in a hydraulic door closer for a storm or screen door, but may provide useful benefits in other closer applications that are subject to a wide range of temperatures.

[0044] The incorporation of the overflow chamber or reservoir within the closer allows a space for hydraulic fluid to expand in high temperature situations which controls or tempers the pressure build up and eliminates the hydraulic fluid leakage condition associated with high internal fluid pressures. It may be desirable to incorporate a small one way check valve in the overflow chamber, which will work to reduce or eliminate any back pressure in the closer as the temperature and pressure change during use. This also serves as a means to allow the overflow chamber to be open to ambient air pressure.

[0045] Hydraulic fluid and hydraulic oil are terms that are sometimes used interchangeably, but they are not necessarily the same. Although hydraulic oil is a fluid, hydraulic fluid can include other fluids besides just oil, such as water, water-oil emulsions, salt solutions, and the like. However, embodiments of the present disclosure are contemplated as employing the more general term hydraulic fluid, which is generally referred to as oil or fluid in this specification. Embodiments of the present disclosure are not meant to be limited to hydraulic oil only, but to any suitable hydraulic fluid or fluids.

[0046] In addition to the expansion due to high temperature, the overflow or expansion chamber may also provide a benefit in cold temperatures by maintaining a prescribed oil volume such that the fluid level never becomes too low during cold temperature and fluid contraction resulting from the cold temperature. This is accomplished by having an oil amount maintained in the overflow chamber so when the oil contracts, there is sufficient fluid volume in the closer at the predetermined low temperature requirement.

[0047] With the incorporation of the overflow expansion chamber, the oil pressure and oil level is maintained to a pressure which prevents leakage and provides a consistent oil operating level ensuring proper closer performance at the temperature extremes experienced by storm and screen doors.

[0048] Referring to FIG. 1, the generalized configuration of a rotationally activated hydraulic door closer (100) is illustrated. In the assembled state, the door closer is comprised of a housing (120), a pinion (110) in which an arm (not shown) is typically attached to transfer angular torque from the closer to the door, and mounting tab(s) (200) to affix the closer to the door or a door frame. According to various embodiments, the door closer can include various alternative arrangements and configurations. In particular, alternative door closer arrangements and configurations, including those disclosed in U.S. Pat. Nos. 4,847,946, 5,337,448, and 5,850,671 are hereby incorporated by reference herein for all purposes.

[0049] Referring to FIG. 3A which is a cross-sectional top view of the closer as defined by FIG. 2, there is a biasing spring (210), a piston (190) with check valve (191), and a pinion (110). Also within the closer is hydraulic fluid, typically a hydraulic oil or oil derivative, which is used to dampen the speed of the closer. As the piston moves transversely within the closer body, the pinion (110) rotates as a result of the engagement between the teeth (192) of the piston and the teeth (112) of the pinion, causing the closer arm (not shown) to rotate and pull the door closed. When a closer arm (not shown) is attached to the pinion and rotated as the door is opened, the pinion gear teeth (112) apply a force to the piston gear teeth (192) to move the piston (190) in a direction that further compresses the spring and causing oil to flow from the unpressurized side of the piston through one-way check valve (191) to the pressurized side of the piston. When the door is released to close, the biasing spring urges the piston toward the pressurized side of the piston (230). Oil on the pressurized side of the closer is displaced but is prevented from flowing back through the check valve so that oil flows through the speed control chamber (not shown), and speed control valve (not shown) to the unpressurized side of the piston (240).

[0050] FIG. 3B depicts an alternate embodiment similar to the embodiment shown in FIG. 3A, but in which a piston seal (193) also functions as a check valve. In the embodiment shown in FIG. 3B, the piston seal (193) comprises a sealing region that creates a fluid-tight seal between the piston (190) and the inner wall of the housing (120) when the pressure on the pressurized side of the piston (230) exceeds the pressure of the unpressurized side of the piston (240). When the door is opened, the pinion gear teeth (112) apply a force to the piston gear teeth (192) to move the piston (190) in a direction that further compresses the spring and displaces the oil from unpressurized side of the piston around the sides of the piston and past the piston seal (193) to the pressurized side of the piston. When the door is released to close, the biasing spring urges the piston toward the pressurized side of the piston (230). Oil on the pressurized side of the closer is displaced but is prevented from flowing past the piston seal (193) so that oil flows through the speed control chamber (not shown), and speed control valve (not shown) to the unpressurized side of the piston (240).

[0051] FIG. 3C is a cross-sectional top close up view of the alternative embodiment as defined by FIG. 3B. Additional cross-sectional, front and side views of the closer of FIG. 3A are illustrated in FIGS. 4-7. FIG. 5 is a cross-section front view of the closer as defined by FIG. 4 illustrating pinion (110) and the sealing portion of closer piston (194). FIG. 6 is a front view of the closer defining the cross section for FIG. 7 and illustrates pinion (110) and mounting tabs (200). FIG. 7 is a cross section defined by FIG. 6 and illustrates pinion (110) and housing (120).

[0052] Referring to FIG. 9A, chamber (123) is an overflow chamber with horizontal overflow chamber screw plug (183) and overflow chamber vertical plug (140) for an embodiment which relies on fluid dynamics to allow fluid (oil) volume fluctuation based upon temperature changes. The chamber in this embodiment is oriented horizontally, and via an overflow connecting chamber (121) permits the expansion and contraction of oil volume based upon temperature changes while maintaining an overall internal oil level and pressure that allows the closer to operate normally. By allowing the internal oil to expand and contract in the overflow chamber as temperature increases and decreases, the oil pressure is maintained at a limited and/or consistent pressure preventing the oil leaks previously described. Furthermore, sizing and locating the overflow chamber properly ensures the oil level remains at the level necessary to ensure normal operation of the closer at all temperatures. That is, even when the oil contracts and the oil level drops to the low temperature line as depicted in FIG. 9A, there is still sufficient oil within the closer to allow the closer to operate normally.

[0053] In FIG. 9A, the oil is typically regulated by a speed control valve (220), to control the flow of oil from the pressurized side of the piston (230) to the unpressurized side (240) of the piston. The biasing spring in this embodiment is under compression when assembled within the closer. The spring exerts a biasing load on the piston, which is in the neutral state as illustrated, and is balanced within the housing resulting in no torque at the pinion. When a closer arm (not shown) is attached to the pinion (110) and rotated as the door is opened, the pinion gear teeth (112) apply a force to the piston gear teeth (192) to move the piston (190) in a direction that further compresses the spring and causing oil to flow from the unpressurized side of the piston through one-way check valve (191) to the pressurized side of the piston. When the door is released to close, the biasing spring urges the piston toward the pressurized side of the piston (230). Oil on the pressurized side of the closer is displaced and flows through the speed control chamber (250), and valve (220) to the unpressurized side of the piston (240).

[0054] FIG. 9B is a cross-sectional front view of an alternate embodiment of the closer as defined by FIG. 8, in which the flow of oil from the pressurized side of the piston to the unpressurized side of the piston is regulated by an alternate type of device. In the alternate embodiment shown in FIG. 9B, the oil may be regulated by another type of device (225) to control the flow of oil from the pressurized side of the piston (230) to the unpressurized side (240) of the piston. Such speed control devices (225) may include a membrane comprising perforations of a particular size, a filter or screen comprising a mesh with a particular open area, an orifice of a particular diameter, or other similar device known to one skilled in the art. The biasing spring in this embodiment is under compression when assembled within the closer. The spring exerts a biasing load on the piston, which is in the neutral state as illustrated, and is balanced within the housing resulting in no torque at the pinion. When a closer arm (not shown) is attached to the pinion (110) and rotated as the door is opened, the pinion gear teeth (112) apply a force to the piston gear teeth (192) to move the piston (190) in a direction that further compresses the spring and causing oil to flow from the unpressurized side of the piston through one-way check valve (191) to the pressurized side of the piston. When the door is released to close, the biasing spring urges the piston toward the pressurized side of the piston (230). Oil on the pressurized side of the closer is displaced and flows at a controlled speed through the speed control chamber (250) and speed control device (225) to the unpressurized side of the piston (240).

[0055] FIG. 9C is a cross-sectional front view of the another alternate embodiment of the closer as defined by FIG. 8, where the oil is regulated by a speed control device located in the piston to control the flow of oil from the pressurized side of the piston through the piston to the unpressurized side of the piston. In the other alternate embodiment shown in FIG. 9C, the oil may be regulated by a speed control device (226) located in piston (190) to control the flow of oil from the pressurized side of the piston (230) through the piston (190) to the unpressurized side (240) of the piston. Such speed control devices (226) may include a membrane comprising perforations of a particular size, a filter or screen comprising a mesh with a particular open area, an orifice of a particular diameter, or other similar device known to one skilled in the art. The biasing spring in this embodiment is under compression when assembled within the closer. The spring exerts a biasing load on the piston, which is in the neutral state as illustrated, and is balanced within the housing resulting in no torque at the pinion. When a closer arm (not shown) is attached to the pinion (110) and rotated as the door is opened, the pinion gear teeth (112) apply a force to the piston gear teeth (192) to move the piston (190) in a direction that further compresses the spring and causing oil to flow from the unpressurized side of the piston through the speed control device (226) to the pressurized side of the piston. When the door is released to close, the biasing spring urges the piston toward the pressurized side of the piston (230). Oil on the pressurized side of the closer is displaced and flows at a controlled speed through the speed control device (226) to the unpressurized side of the piston (240).

[0056] Referring to FIG. 11, chamber (124) is an overflow chamber with vertical overflow chamber screw plug (184) for an alternate embodiment which relies on fluid dynamics to allow fluid (oil) volume fluctuation based upon temperature changes. The chamber in this embodiment is oriented vertically, and permits the expansion and contraction of oil volume based upon temperature changes while maintaining an overall internal oil level and pressure that allows the closer to operate normally. As with the horizontal chamber, the oil pressure and level is maintained at levels that ensure normal operation of the closer at all temperatures.

[0057] Referring to FIG. 13, chamber (125) is an active overflow chamber with angular overflow chamber screw plug (185) for yet another embodiment that relies on fluid dynamics to allow fluid (oil) volume fluctuation based upon temperature changes. The chamber in this embodiment is oriented at an angle, and permits the expansion and contraction of oil volume based upon temperature changes while maintaining an overall internal oil level and pressure that allows the closer to operate normally. As with the horizontal and vertical chambers, the oil pressure and level is maintained at levels that ensure normal operation of the closer at all temperatures.

[0058] FIG. 14 illustrates another embodiment having a spring-biased piston in the overflow chamber. The addition of a spring-biased piston in the overflow chamber further enhances the operational performance of the closer. In the horizontally-oriented chamber depicted in FIG. 14, for example, overflow chamber (123) contains a piston (280) backed by a spring (282) and carrying a piston seal (281). The piston would be located at an intermediate position within the overflow chamber at an ambient (room temperature) state. This intermediate position is illustrated in FIG. 14A showing an enlargement of the overflow chamber components of FIG. 14. In a low temperature state, the oil within the closer would contract due to a decrease in temperature. This would decrease the volume of the oil and the spring-biased overflow chamber piston would move in a direction decreasing the volume within the overflow chamber, but yet maintaining an overall internal oil level and pressure within the closer allowing the closer to operate normally. This low temperature configuration of the overflow components is illustrated in FIG. 14B. Alternately, in a high temperature state, the oil within the closer would expand due to an increase in temperature. This would increase the volume of the oil and the overflow chamber piston would move in a direction increasing the volume within the overflow chamber, but yet maintaining an overall internal oil level and pressure within the closer allowing the closer to operate normally. This high temperature configuration of the overflow chamber components is illustrated in FIG. 14C. The spring (282) that biases the piston must be carefully sized such that throughout the entire operating temperature range of the closer, the expanding oil can overcome the spring force and increase the effective volume of the overflow chamber as the oil temperature increases; yet while the oil temperature decreases and the oil contracts, the spring force can overcome the force of friction between the piston seal and overflow chamber thereby allowing the spring to extend and reduce the effective volume of the overflow chamber.

[0059] Referring to FIG. 16, chamber (123) is a horizontal overflow chamber with horizontal overflow chamber having a spring-biased piston (280) in the overflow chamber. The chamber in this embodiment is located in an interior region of the closer defined by the inside diameter of the biasing spring and permits the expansion and contraction of oil volume based upon the positions of the overflow chamber piston (280) with related overflow chamber piston seal (281) and overflow chamber spring (282) in the overflow chamber to maintain an overall internal oil level and pressure that allows the closer to operate normally at all temperatures. By allowing the internal oil to expand and contract in the overflow chamber as temperature increases and decreases, the oil pressure is maintained at essentially the same pressure as at ambient temperatures, and prevents the oil leaks previously described.

[0060] Referring to FIG. 17, another embodiment related to FIG. 14 is illustrated, but instead of having a piston seal to create a fluid-tight seal within the piston in the overflow chamber, FIG. 17 includes a close fitted overflow chamber piston (380) within a horizontal overflow chamber (323 Therefore, according to FIG. 17, no piston seal is required due to close machining tolerance of the components. As in FIG. 14, a spring biases the overflow chamber piston (380) as the volume and pressure of the oil increase and decrease with changes in the operating temperature of the closer. In the horizontally-oriented chamber depicted in FIG. 17, for example, overflow chamber (323) contains a piston (380) backed by a spring (382)). As in FIG. 14B, a low temperature configuration of the overflow components is illustrated in FIG. 17B. Also as in FIG. 14C, a high temperature configuration of the overflow chamber components is illustrated in FIG. 17C. Also as in FIG. 14, the spring (382) that biases the piston must be carefully sized such that throughout the entire operating temperature range of the closer, the expanding oil can overcome the spring force and increase the effective volume of the overflow chamber as the oil temperature increases; yet while the oil temperature decreases and the oil contracts, the spring force can overcome the force of friction between the overflow chamber piston and overflow chamber thereby allowing the spring to extend and reduce the effective volume of the overflow chamber. Operation in FIG. 17 can be substantially similar to that described with respect to FIG. 14, above.

[0061] According to a variation of the embodiment shown in FIGS. 17, 17A, 17B, and 17C, the close fitted overflow chamber piston (380) is formed of a single portion of a single durometer of a soft material configured to seal the piston (380) to the overflow chamber (323) with increased tolerance for less precision in the close fitting aspect. In some embodiments that employ the chamber piston (380) being formed of the single portion of the single durometer, increased tolerance for less precision in the close fitting aspect, the chamber piston (380) is not closely fitted to the overflow chamber (323). In some embodiments, the single durometer overflow chamber piston (380) is composed of a substantially soft material that provides increased tolerance with respect to the single durometer overflow chamber piston (380) and the overflow chamber (323) as the single durometer overflow chamber piston contacts and slides within the overflow chamber during operation. In other embodiments, the overflow chamber piston (380) creates a fluid tight seal that substantially prevents one or more fluids from bypassing the overflow chamber piston (380).

[0062] Referring to FIG. 18, another embodiment related to FIGS. 14 and 17 is illustrated, but instead of having a piston seal to create a fluid-tight seal between the piston and the overflow chamber and a spring backing the piston, FIG. 18 includes a close fitted overflow chamber piston (480) within a horizontal overflow chamber (423), and also introduces a compressible fluid air-spring instead of a coil-based spring, where an overflow chamber compressible fluid (482) within the horizontal overflow chamber is compressed like a spring at higher temperatures or anytime there are greater temperatures present. As used herein, a fluid or a compressible fluid can include liquids, gases, or any combinations or suitable variations thereof. Therefore, according to FIG. 18, no piston seal is required due to close fitment and tolerance of the components, and no biasing coil spring is necessary. Functionally similar to FIG. 14, a compressible fluid (482) (e.g., air or other gas) biases the overflow chamber piston (480) as the volume and pressure of the oil increase and decrease with changes in the operating temperature of the closer. In the horizontally-oriented chamber depicted in FIG. 18, for example, overflow chamber (423) contains a piston (480) backed by the compressible fluid (482). As in FIG. 14B, a low temperature configuration of the overflow components is illustrated in FIG. 18B. Also as in FIG. 14C, a high temperature configuration of the overflow chamber components is illustrated in FIG. 18C. Also as in FIG. 14, the compressible fluid (482) that biases the piston must be carefully volumetrically sized, selected and caused to fill the horizontal overflow chamber (423) such that throughout the entire operating temperature range of the closer, the expanding oil can overcome the fluid compression force and increase the effective volume of the overflow chamber as the oil temperature increases; yet while the oil temperature decreases and the oil contracts, the fluid compression force can overcome the force of friction between the overflow chamber piston and overflow chamber thereby allowing the compressible fluid to expand and reduce the effective volume of the overflow chamber. Operation in FIG. 18 can be substantially similar to that described with respect to FIG. 14, above.

[0063] According to some embodiments, the hydraulic fluid will balance in pressure with the overflow chamber piston (480). When the fluid expands, the overflow chamber piston will compress the compressible material until the force is balanced on the overflow chamber piston. Likewise, when the hydraulic fluid is cooled, the overflow chamber piston will move to balance the pressure on the overflow piston. In such cases, observed variations include the friction of the overflow piston for movement.

[0064] Referring to FIG. 19, another embodiment having a spring-biased piston in the overflow chamber is shown. FIG. 19 introduces an overflow chamber piston having first and second portions, which can be integral, yet have different durometers (e.g., hardness). In the horizontally-oriented chamber depicted in FIG. 19, for example, overflow chamber (523) contains piston with a first portion (580) and a second portion (581), both backed by a spring (582). According to various embodiments, the second portion (581) of the piston can operate as a piston seal, similar to other piston seal embodiments herein. In some embodiments, the second (581), sealing portion of overflow chamber piston is composed of a substantially soft material that provides increased tolerance with respect to the overflow chamber piston and the overflow chamber as the overflow chamber piston contacts and slides within the overflow chamber during operation. In other embodiments, the overflow chamber piston second portion (581) creates a fluid tight seal that substantially prevents one or more fluids from bypassing the overflow chamber piston.

[0065] The piston composed of first and second portions (580 and 581) would be located at an intermediate position within the overflow chamber at an ambient (room temperature) state. This intermediate position is illustrated in FIG. 19A showing an enlargement of the overflow chamber components of FIG. 19. In a low temperature state, the oil within the closer would contract due to a decrease in temperature. A low temperature configuration of the overflow components is illustrated in FIG. 19B. A high temperature configuration of the overflow chamber components is illustrated in FIG. 19C. The spring (582) that biases the piston must be carefully sized such that throughout the entire operating temperature range of the closer, the expanding oil can overcome the spring force and increase the effective volume of the overflow chamber as the oil temperature increases; yet while the oil temperature decreases and the oil contracts, the spring force can overcome the force of friction between the piston seal and overflow chamber thereby allowing the spring to extend and reduce the effective volume of the overflow chamber.

[0066] Referring to FIG. 20, another embodiment is shown where the piston is a multi-durometer piston, and where the piston is biased with a compressible fluid (682) acting as an air spring in the overflow chamber. In the horizontally-oriented chamber depicted in FIG. 20, for example, overflow chamber (623) contains a piston (680) backed by an overflow chamber compressible fluid (682) and carrying a piston sealing portion (681), which can include a piston seal or a portion of the piston that is a second durometer different than other parts of the piston (680). An ambient (room temperature) state is illustrated in FIG. 20A showing an enlargement of the overflow chamber components of FIG. 20. A low temperature configuration of the overflow components is illustrated in FIG. 20B. A high temperature configuration of the overflow chamber components is illustrated in FIG. 20C. The compressible fluid (682) that biases the piston must be selected to be volumetrically sized such that throughout the entire operating temperature range of the closer, the expanding oil can overcome the compressible fluid biasing force and increase the effective volume of the overflow chamber as the oil temperature increases; yet while the oil temperature decreases and the oil contracts, the compressible fluid biasing force can overcome the force of friction between the piston seal or second durometer portion of the piston and overflow chamber thereby allowing the compressible fluid to expand and reduce the effective volume of the overflow chamber. In embodiments not shown, the piston can utilize a piston seal and can alternatively have a single portion with a single durometer. In yet other embodiments not shown herein other types of fluids (such as gases), foams, or other resilient materials can be positioned behind the overflow chamber piston under similar principles of operation.

[0067] In various embodiments where the overflow chamber piston includes either a single durometer or multiple durometer portions, a sealing portion of the overflow chamber piston is composed of a substantially soft material that provides increased tolerance with respect to the overflow chamber piston and the overflow chamber as the overflow chamber piston contacts and slides within the overflow chamber during operation. In other embodiments, the overflow chamber piston seal creates a fluid tight seal that substantially prevents one or more fluids from bypassing the overflow chamber piston.

[0068] Referring to FIGS. 21 and 22, a static overflow chamber (127) is an overflow chamber with a non-variable internal volume (128) for an alternate embodiment which relies on fluid dynamics to allow fluid (oil) volume fluctuation based upon temperature changes. The static overflow chamber (127) can have an overflow chamber top (187) that can be fixed or removable. The chamber in this embodiment is oriented horizontally, as shown, but also includes a vertical component and permits the expansion and contraction of oil volume based upon temperature changes while maintaining an overall internal oil level and pressure that allows the closer to operate normally. As with other embodiments chamber, the oil pressure and level is maintained at levels that ensure normal operation of the closer at all temperatures.

[0069] In some embodiments a speed of the closer can be adjusted using a speed control valve, or by prescribed leakage from the pressurized to unpressurized hydraulic sides of the overflow chamber piston.

[0070] Referring to FIGS. 23 and 24, a gravity-operated overflow chamber (126) is an overflow chamber with a gravity and piston-based variable internal volume of the overflow chamber (129) for an alternate embodiment which relies on fluid dynamics to allow fluid (oil) volume fluctuation based upon temperature changes. The gravity-operated overflow chamber (126) can have an overflow chamber screw plug (186) that can be fixed or removable. The chamber in this embodiment is oriented at least partially vertically (to cause at least some gravitational force to pull the piston toward the earth), or fully vertically, as shown. Preferably, various embodiments of the gravity-operated overflow chamber (126) include at least a vertical component and permits the expansion and contraction of oil volume based upon temperature changes while maintaining an overall internal oil level and pressure that allows the closer to operate normally. As with other embodiments overflow chambers described herein, the oil pressure and level is maintained at levels that ensure normal operation of the closer at all temperatures. FIGS. 25-27 represent various optional embodiments of the gravity-operated overflow chamber over FIG. 24.

[0071] As increasing operating temperatures cause the oil volume and pressure to rise the piston also rises, and that as decreasing operating temperatures cause the oil volume and pressure to drop the piston also drops due to the force of gravity. This gravity-based operation is in contrast to embodiments herein that instead utilize a biasing (e.g., coil) spring or compressible fluid that operates as an air spring. In this sense, the embodiments shown in FIGS. 23 and 24 can be said to utilize a gravity spring.

[0072] Referring to FIG. 25, a close-fitted gravity-operated piston (130) within the gravity-operated overflow chamber is shown. As the close-fitted gravity-operated piston (130) is caused to move by variable pressures, an oil volume can also vary according to temperature. The overflow chamber (129) can be oriented at least partially vertically, and can be of variable height, width, and shape according to various embodiments. According to a variation of the embodiment shown in FIG. 25, the gravity-operated piston (130) is a single durometer overflow chamber piston configured to contact and slide within the overflow chamber such that the single durometer overflow chamber piston seals to the overflow chamber. In various embodiments, the single durometer overflow chamber piston is composed of a substantially soft material that provides increased tolerance with respect to the single durometer overflow chamber piston and the overflow chamber as the single durometer overflow chamber piston contacts and slides within the overflow chamber during operation.

[0073] Referring to FIG. 26, a gravity-operated piston (132) is within the gravity-operated overflow chamber, and the gravity-operated piston (132) is attached to a seal (135), which can be a separate component and/or material as compared to piston (132), as shown. As the gravity-operated piston (132) is caused to move by variable pressures, an oil volume can also vary according to temperature. As in FIG. 25, the overflow chamber (129) can be oriented at least partially vertically, and can be of variable height, width, and shape according to various embodiments.

[0074] Referring to FIG. 27, a gravity-operated piston (131) is within the gravity-operated overflow chamber, and the gravity-operated piston (131) includes a sealing portion (133), which can be integral with the piston (131). The sealing portion (133) of the piston (131) can be a portion of the piston with a different durometer than another (e.g., non-sealing) portion of piston (131). As the gravity-operated piston (131) is caused to move by variable pressures, an oil volume can also vary according to temperature. As in FIG. 25, the overflow chamber (129) can preferably be oriented at least partially vertically (so as to take advantage of gravity's pull on the gravity-operated piston (131)), and can be of variable height, width, and shape according to various embodiments. In some embodiments, the sealing portion (133) of the piston (131) is composed of a substantially soft material that provides increased tolerance with respect to the piston (131) and the overflow chamber as the single durometer overflow chamber piston contacts and slides within the overflow chamber during operation. In other embodiments, the overflow chamber piston sealing portion (133) creates a fluid tight seal that substantially prevents one or more fluids from bypassing the piston (131).

Selected Embodiments

[0075] The following embodiments, designated by letter and number, are intended to further illustrate the present disclosure, but should not be construed to unduly limit this disclosure.

[0076] CF1. A hydraulic door closer comprising hydraulic fluid in a housing fitted with i) a biasing spring attached to a piston having geared teeth and a check valve, ii) a geared pinion, iii) a speed control chamber, and iv) a hydraulic fluid overflow chamber, the hydraulic fluid overflow chamber comprising an overflow chamber piston closely fitted to the hydraulic fluid overflow chamber, the overflow chamber piston and the hydraulic fluid overflow chamber forming a sealed compression chamber filled with a compressible fluid that biases the overflow chamber piston when the overflow chamber piston compresses the compressible fluid when the hydraulic fluid is in an expanded state.

[0077] CF2. The hydraulic door closer of any of the preceding embodiments wherein the overflow chamber piston closely fitted to the hydraulic fluid overflow chamber creates a fluid tight seal that substantially prevents one or more fluids from bypassing the overflow chamber piston.

[0078] CF3. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber has a predetermined volume sufficient to hold expanded hydraulic fluid at an elevated temperature.

[0079] CF4. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber maintains an amount of hydraulic fluid so that when the hydraulic fluid contracts there is sufficient hydraulic fluid in the closer.

[0080] CF5. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber holds sufficient hydraulic fluid when the hydraulic fluid is in either an expanded or in contracted state.

[0081] CF6. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber is a vertical chamber, a horizontal chamber, or an angled chamber.

[0082] CF7. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber is in an interior region of the closer.

[0083] CF8. The hydraulic door closer of any of the preceding embodiments further comprising a speed control valve.

[0084] CF9. The hydraulic door closer of any of the preceding embodiments further comprising horizontal and vertical speed control chamber plugs.

[0085] CF10. The hydraulic door closer of any of the preceding embodiments further comprising a hydraulic overflow chamber check valve.

[0086] CF11. The hydraulic door closer of any of the preceding embodiments wherein the biasing spring is a compression spring.

[0087] CS1. A hydraulic door closer comprising hydraulic fluid in a housing fitted with i) a biasing spring attached to a piston having geared teeth and a check valve, ii) a geared pinion, iii) a speed control chamber, and iv) a hydraulic fluid overflow chamber, the hydraulic fluid overflow chamber comprising an overflow chamber piston closely fitted to the hydraulic fluid overflow chamber, and an overflow chamber spring.

[0088] CS2. The hydraulic door closer of any of the preceding embodiments wherein the overflow chamber piston closely fitted to the hydraulic fluid overflow chamber creates a fluid tight seal that substantially prevents one or more fluids from bypassing the overflow chamber piston.

[0089] CS3. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber has a predetermined volume sufficient to hold expanded hydraulic fluid at an elevated temperature.

[0090] CS4. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber maintains an amount of hydraulic fluid so that when the hydraulic fluid contracts there is sufficient hydraulic fluid in the closer.

[0091] CS5. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber holds sufficient hydraulic fluid when the hydraulic fluid is in either an expanded or in contracted state.

[0092] CS6. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber is a vertical chamber, a horizontal chamber, or an angled chamber.

[0093] CS7. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber is in an interior region of the closer.

[0094] CS8. The hydraulic door closer of any of the preceding embodiments further comprising a speed control valve.

[0095] CS9. The hydraulic door closer of any of the preceding embodiments further comprising horizontal and vertical speed control chamber plugs.

[0096] CS10. The hydraulic door closer of any of the preceding embodiments further comprising a hydraulic overflow chamber check valve.

[0097] CS11. The hydraulic door closer of any of the preceding embodiments wherein the biasing spring is a compression spring.

[0098] DD1. A hydraulic door closer comprising hydraulic fluid in a housing fitted with i) a biasing spring attached to a piston having geared teeth and a check valve, ii) a geared pinion, iii) a speed control chamber, and iv) a hydraulic fluid overflow chamber comprising an overflow chamber piston having a first portion and a second portion, the first portion having a first durometer and the second portion having a second durometer, wherein the second portion operates as an overflow chamber piston seal, and an overflow chamber spring.

[0099] DD2. The hydraulic door closer of any of the preceding embodiments wherein the overflow chamber piston seal creates a fluid tight seal that substantially prevents one or more fluids from bypassing the overflow chamber piston.

[0100] DD3. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber has a predetermined volume sufficient to hold expanded hydraulic fluid at an elevated temperature.

[0101] DD4. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber maintains an amount of hydraulic fluid so that when the hydraulic fluid contracts there is sufficient hydraulic fluid in the closer.

[0102] DD5. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber holds sufficient hydraulic fluid when the hydraulic fluid is in either an expanded or in contracted state.

[0103] DD6. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber is a vertical chamber, a horizontal chamber, or an angled chamber.

[0104] DD7. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber is in an interior region of the closer.

[0105] DD8. The hydraulic door closer of any of the preceding embodiments further comprising a speed control valve.

[0106] DD9. The hydraulic door closer of any of the preceding embodiments further comprising horizontal and vertical speed control chamber plugs.

[0107] DD10. The hydraulic door closer of any of the preceding embodiments further comprising a hydraulic overflow chamber check valve.

[0108] DD11. The hydraulic door closer of any of the preceding embodiments wherein the biasing spring is a compression spring.

[0109] SS1. A hydraulic door closer comprising hydraulic fluid in a housing fitted with i) a biasing spring attached to a piston having geared teeth and a check valve, ii) a geared pinion, iii) a speed control chamber, and iv) a hydraulic fluid overflow chamber comprising an overflow chamber piston, and an overflow chamber piston seal, the overflow chamber piston and the hydraulic fluid overflow chamber defining a sealed compression chamber filled with compressible fluid that biases the overflow chamber piston when the overflow chamber piston compresses the compressible fluid when the hydraulic fluid is in an expanded state.

[0110] SS2. The hydraulic door closer of any of the preceding embodiments wherein the overflow chamber piston seal creates a fluid tight seal that substantially prevents one or more fluids from bypassing the overflow chamber piston.

[0111] SS3. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber has a predetermined volume sufficient to hold expanded hydraulic fluid at an elevated temperature.

[0112] SS4. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber maintains an amount of hydraulic fluid so that when the hydraulic fluid contracts there is sufficient hydraulic fluid in the closer.

[0113] SS5. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber holds sufficient hydraulic fluid when the hydraulic fluid is in either an expanded or in contracted state.

[0114] SS6. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber is a vertical chamber, a horizontal chamber, or an angled chamber.

[0115] SS7. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber is in an interior region of the closer.

[0116] SS8. The hydraulic door closer of any of the preceding embodiments further comprising a speed control valve.

[0117] SS9. The hydraulic door closer of any of the preceding embodiments further comprising horizontal and vertical speed control chamber plugs.

[0118] SS10. The hydraulic door closer of any of the preceding embodiments further comprising a hydraulic overflow chamber check valve.

[0119] SS11. The hydraulic door closer of any of the preceding embodiments wherein the biasing spring is a compression spring.

[0120] DS1. A hydraulic door closer comprising hydraulic fluid in a housing fitted with i) a biasing spring attached to a piston having geared teeth and a check valve, ii) a geared pinion, iii) a speed control chamber, iv) a hydraulic fluid overflow chamber comprising an overflow chamber piston having a first portion and a second portion, the first portion having a first durometer and the second portion having a second durometer, wherein the second portion operates as an overflow chamber piston seal, wherein the overflow chamber piston and the hydraulic fluid overflow chamber form a sealed compression chamber filled with compressible fluid that biases the overflow chamber piston when the overflow chamber piston compresses the compressible fluid when the hydraulic fluid is in an expanded state.

[0121] DS2. The hydraulic door closer of any of the preceding embodiments wherein the overflow chamber piston seal creates a fluid tight seal that substantially prevents one or more fluids from bypassing the overflow chamber piston.

[0122] DS3. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber has a predetermined volume sufficient to hold expanded hydraulic fluid at an elevated temperature.

[0123] DS4. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber maintains an amount of hydraulic fluid so that when the hydraulic fluid contracts there is sufficient hydraulic fluid in the closer.

[0124] DS5. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber holds sufficient hydraulic fluid when the hydraulic fluid is in either an expanded or in contracted state.

[0125] DS6. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber is a vertical chamber, a horizontal chamber, or an angled chamber.

[0126] DS7. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber is in an interior region of the closer.

[0127] DS8. The hydraulic door closer of any of the preceding embodiments further comprising a speed control valve.

[0128] DS9. The hydraulic door closer of any of the preceding embodiments further comprising horizontal and vertical speed control chamber plugs.

[0129] DS10. The hydraulic door closer of any of the preceding embodiments further comprising a hydraulic overflow chamber check valve.

[0130] DS11. The hydraulic door closer of any of the preceding embodiments wherein the biasing spring is a compression spring.

[0131] GP1. A hydraulic door closer comprising hydraulic fluid in a housing fitted with i) a biasing spring attached to a piston having geared teeth and a check valve, ii) a geared pinion, iii) a speed control chamber, and iv) an at least partially vertical hydraulic fluid overflow chamber comprising a gravity-operated overflow chamber piston, wherein a gravitational force biases the overflow chamber piston when the hydraulic fluid is in an expanded state.

[0132] GP2. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber has a predetermined volume sufficient to hold expanded hydraulic fluid at an elevated temperature.

[0133] GP3. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber maintains an amount of hydraulic fluid so that when the hydraulic fluid contracts there is sufficient hydraulic fluid in the closer.

[0134] GP4. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber holds sufficient hydraulic fluid when the hydraulic fluid is in either an expanded or in contracted state.

[0135] GP5. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber is a fully vertical chamber.

[0136] GP6. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber is in an interior region of the closer.

[0137] GP7. The hydraulic door closer of any of the preceding embodiments further comprising a speed control valve.

[0138] GP8. The hydraulic door closer of any of the preceding embodiments further comprising horizontal and vertical speed control chamber plugs.

[0139] GP9. The hydraulic door closer of any of the preceding embodiments further comprising a hydraulic overflow chamber check valve.

[0140] GP10. The hydraulic door closer of any of the preceding embodiments wherein the biasing spring is a compression spring.

[0141] SD1. A hydraulic door closer comprising hydraulic fluid in a housing fitted with i) a biasing spring attached to a piston having geared teeth and a check valve, ii) a geared pinion, iii) a speed control chamber, and iv) a hydraulic fluid overflow chamber comprising a single durometer overflow chamber piston configured to contact and slide within the overflow chamber such that the single durometer overflow chamber piston seals to the overflow chamber, and an overflow chamber spring.

[0142] SD2. The hydraulic door closer of any of the preceding embodiments wherein the single durometer overflow chamber piston is composed of a substantially soft material that provides increased tolerance with respect to the single durometer overflow chamber piston and the overflow chamber as the single durometer overflow chamber piston contacts and slides within the overflow chamber.

[0143] SD3. The hydraulic door closer of any of the preceding embodiments wherein the single durometer overflow chamber piston creates a fluid tight seal that substantially prevents one or more fluids from bypassing the overflow chamber piston.

[0144] SD4. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber has a predetermined volume sufficient to hold expanded hydraulic fluid at an elevated temperature.

[0145] SD5. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber maintains an amount of hydraulic fluid so that when the hydraulic fluid contracts there is sufficient hydraulic fluid in the closer.

[0146] SD6. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber holds sufficient hydraulic fluid when the hydraulic fluid is in either an expanded or in contracted state.

[0147] SD7. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber is a vertical chamber, a horizontal chamber, or an angled chamber.

[0148] SD8. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber is in an interior region of the closer.

[0149] SD9. The hydraulic door closer of any of the preceding embodiments further comprising a speed control valve.

[0150] SD10. The hydraulic door closer of any of the preceding embodiments further comprising horizontal and vertical speed control chamber plugs.

[0151] SD11. The hydraulic door closer of any of the preceding embodiments further comprising a hydraulic overflow chamber check valve.

[0152] SD12. The hydraulic door closer of any of the preceding embodiments wherein the biasing spring is a compression spring.

[0153] OD1. A hydraulic door closer comprising hydraulic fluid in a housing fitted with i) a biasing spring attached to a piston having geared teeth and a check valve, ii) a geared pinion, iii) a speed control chamber, iv) a hydraulic fluid overflow chamber comprising a single durometer overflow chamber piston configured to contact and slide within the overflow chamber such that the single durometer overflow chamber piston seals to the overflow chamber, wherein the single durometer overflow chamber piston and the hydraulic fluid overflow chamber form a sealed compression chamber filled with compressible fluid that biases the single durometer overflow chamber piston when the overflow chamber piston compresses the compressible fluid when the hydraulic fluid is in an expanded state.

[0154] OD2. The hydraulic door closer of any of the preceding embodiments wherein the single durometer overflow chamber piston is composed of a substantially soft material that provides increased tolerance with respect to the single durometer overflow chamber piston and the overflow chamber as the single durometer overflow chamber piston contacts and slides within the overflow chamber.

[0155] OD3. The hydraulic door closer of any of the preceding embodiments wherein the single durometer overflow chamber piston creates a fluid tight seal that substantially prevents one or more fluids from bypassing the overflow chamber piston.

[0156] OD4. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber has a predetermined volume sufficient to hold expanded hydraulic fluid at an elevated temperature.

[0157] OD5. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber maintains an amount of hydraulic fluid so that when the hydraulic fluid contracts there is sufficient hydraulic fluid in the closer.

[0158] OD6. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber holds sufficient hydraulic fluid when the hydraulic fluid is in either an expanded or in contracted state.

[0159] OD7. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber is a vertical chamber, a horizontal chamber, or an angled chamber.

[0160] OD8. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber is in an interior region of the closer.

[0161] OD9. The hydraulic door closer of any of the preceding embodiments further comprising a speed control valve.

[0162] OD10. The hydraulic door closer of any of the preceding embodiments further comprising horizontal and vertical speed control chamber plugs.

[0163] OD11. The hydraulic door closer of any of the preceding embodiments further comprising a hydraulic overflow chamber check valve.

[0164] OD12. The hydraulic door closer of any of the preceding embodiments wherein the biasing spring is a compression spring.

[0165] SV1. A hydraulic door closer comprising hydraulic fluid in a housing fitted with i) a biasing spring attached to a piston having geared teeth and a check valve, ii) a geared pinion, iii) a speed control chamber, and iv) a vertical hydraulic fluid overflow chamber, the hydraulic fluid overflow chamber comprising an overflow chamber piston, wherein the overflow chamber piston is biased when the hydraulic fluid is in an expanded state.

[0166] SV2. The hydraulic door closer of any of the preceding embodiments, wherein the overflow chamber piston is selected from the group consisting of: a piston with a separate seal, a piston closely fitted to the hydraulic fluid overflow chamber, a piston having a first portion composed of a first durometer and a second portion composed of a second durometer that operates as an overflow chamber piston seal, and a piston composed of a single durometer configured to contact and slide within the overflow chamber such that the single durometer overflow chamber piston seals to the overflow chamber.

[0167] SV3. The hydraulic door closer of any of the preceding embodiments, wherein the single durometer overflow chamber piston is composed of a substantially soft material that provides increased tolerance with respect to the single durometer overflow chamber piston and the overflow chamber as the single durometer overflow chamber piston contacts and slides within the overflow chamber.

[0168] SV4. The hydraulic door closer of any of the preceding embodiments, wherein the hydraulic fluid overflow chamber is biased by an overflow compression spring.

[0169] SV5. The hydraulic door closer of any of the preceding embodiments, wherein the overflow chamber piston and the hydraulic fluid overflow chamber form a sealed compression chamber filled with a compressible fluid that-biases the overflow chamber piston when the overflow chamber piston compresses the compressible fluid when the hydraulic fluid is in an expanded state.

[0170] SV6. The hydraulic door closer of any of the preceding embodiments, wherein the overflow chamber piston is a gravity-operated overflow chamber piston, and wherein a gravitational force biases the overflow chamber piston when the hydraulic fluid is in an expanded state.

[0171] SV7. The hydraulic door closer of any of the preceding embodiments, wherein the overflow chamber piston creates a fluid tight seal that substantially prevents one or more fluids from bypassing the overflow chamber piston.

[0172] SV8. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber has a predetermined volume sufficient to hold expanded hydraulic fluid at an elevated temperature.

[0173] SV9. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber maintains an amount of hydraulic fluid so that when the hydraulic fluid contracts there is sufficient hydraulic fluid in the closer.

[0174] SV10. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber holds sufficient hydraulic fluid when the hydraulic fluid is in either an expanded or in contracted state.

[0175] SV11. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber is in an interior region of the closer.

[0176] SV12. The hydraulic door closer of any of the preceding embodiments further comprising a speed control valve.

[0177] SV13. The hydraulic door closer of any of the preceding embodiments further comprising horizontal and vertical speed control chamber plugs.

[0178] SV14. The hydraulic door closer of any of the preceding embodiments further comprising a hydraulic overflow chamber check valve.

[0179] SH1. A hydraulic door closer comprising hydraulic fluid in a housing fitted with i) a biasing spring attached to a piston having geared teeth and a check valve, ii) a geared pinion, iii) a speed control chamber, and iv) a horizontal hydraulic fluid overflow chamber, the hydraulic fluid overflow chamber comprising an overflow chamber piston, wherein the overflow chamber piston is biased when the hydraulic fluid is in an expanded state.

[0180] SH2. The hydraulic door closer of any of the preceding embodiments, wherein the overflow chamber piston is selected from the group consisting of: a piston with a separate seal, a piston closely fitted to the hydraulic fluid overflow chamber, a piston having a first portion composed of a first durometer and a second portion composed of a second durometer that operates as an overflow chamber piston seal, and a piston composed of a single durometer configured to contact and slide within the overflow chamber such that the single durometer overflow chamber piston seals to the overflow chamber.

[0181] SH3. The hydraulic door closer of any of the preceding embodiments, wherein the single durometer overflow chamber piston is composed of a substantially soft material that provides increased tolerance with respect to the single durometer overflow chamber piston and the overflow chamber as the single durometer overflow chamber piston contacts and slides within the overflow chamber.

[0182] SH4. The hydraulic door closer of any of the preceding embodiments, wherein the hydraulic fluid overflow chamber is biased by an overflow compression spring.

[0183] SH5. The hydraulic door closer of any of the preceding embodiments, wherein the overflow chamber piston and the hydraulic fluid overflow chamber form a sealed compression chamber filled with a compressible fluid that-biases the overflow chamber piston when the overflow chamber piston compresses the compressible fluid when the hydraulic fluid is in an expanded state.

[0184] SH6. The hydraulic door closer of any of the preceding embodiments, wherein the overflow chamber piston creates a fluid tight seal that substantially prevents one or more fluids from bypassing the overflow chamber piston.

[0185] SH7. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber has a predetermined volume sufficient to hold expanded hydraulic fluid at an elevated temperature.

[0186] SH8. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber maintains an amount of hydraulic fluid so that when the hydraulic fluid contracts there is sufficient hydraulic fluid in the closer.

[0187] SH9. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber holds sufficient hydraulic fluid when the hydraulic fluid is in either an expanded or in contracted state.

[0188] SH10. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber is in an interior region of the closer.

[0189] SH11. The hydraulic door closer of any of the preceding embodiments further comprising a speed control valve.

[0190] SH12. The hydraulic door closer of any of the preceding embodiments further comprising horizontal and vertical speed control chamber plugs.

[0191] SH13. The hydraulic door closer of any of the preceding embodiments further comprising a hydraulic overflow chamber check valve.

[0192] AH1. A hydraulic door closer comprising hydraulic fluid in a housing fitted with i) a biasing spring attached to a piston having geared teeth and a check valve, ii) a geared pinion, iii) a speed control chamber, and iv) an angled hydraulic fluid overflow chamber, the hydraulic fluid overflow chamber comprising an overflow chamber piston, wherein the overflow chamber piston is biased when the hydraulic fluid is in an expanded state.

[0193] AH2. The hydraulic door closer of any of the preceding embodiments, wherein the overflow chamber piston is selected from the group consisting of: a piston with a separate seal, a piston closely fitted to the hydraulic fluid overflow chamber, a piston having a first portion composed of a first durometer and a second portion composed of a second durometer that operates as an overflow chamber piston seal, and a piston composed of a single durometer configured to contact and slide within the overflow chamber such that the single durometer overflow chamber piston seals to the overflow chamber.

[0194] AH3. The hydraulic door closer of any of the preceding embodiments, wherein the single durometer overflow chamber piston is composed of a substantially soft material that provides increased tolerance with respect to the single durometer overflow chamber piston and the overflow chamber as the single durometer overflow chamber piston contacts and slides within the overflow chamber.

[0195] AH4. The hydraulic door closer of any of the preceding embodiments, wherein the hydraulic fluid overflow chamber is biased by an overflow compression spring.

[0196] AH5. The hydraulic door closer of any of the preceding embodiments, wherein the overflow chamber piston and the hydraulic fluid overflow chamber form a sealed compression chamber filled with a compressible fluid that-biases the overflow chamber piston when the overflow chamber piston compresses the compressible fluid when the hydraulic fluid is in an expanded state.

[0197] AH6. The hydraulic door closer of any of the preceding embodiments, wherein the overflow chamber piston is a gravity-operated overflow chamber piston, and wherein a gravitational force biases the overflow chamber piston when the hydraulic fluid is in an expanded state.

[0198] AH7. The hydraulic door closer of any of the preceding embodiments, wherein the overflow chamber piston creates a fluid tight seal that substantially prevents one or more fluids from bypassing the overflow chamber piston.

[0199] AH8. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber has a predetermined volume sufficient to hold expanded hydraulic fluid at an elevated temperature.

[0200] AH9. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber maintains an amount of hydraulic fluid so that when the hydraulic fluid contracts there is sufficient hydraulic fluid in the closer.

[0201] AH10. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber holds sufficient hydraulic fluid when the hydraulic fluid is in either an expanded or in contracted state.

[0202] AH11. The hydraulic door closer of any of the preceding embodiments wherein the hydraulic fluid overflow chamber is in an interior region of the closer.

[0203] AH12. The hydraulic door closer of any of the preceding embodiments further comprising a speed control valve.

[0204] AH13. The hydraulic door closer of any of the preceding embodiments further comprising horizontal and vertical speed control chamber plugs.

[0205] AH14. The hydraulic door closer of any of the preceding embodiments further comprising a hydraulic overflow chamber check valve.

[0206] Various modifications and alterations of this disclosure will become apparent to those skilled in the art without departing from the scope and principles of this disclosure, and it should be understood that this disclosure is not to be unduly limited to the illustrative embodiments set forth hereinabove.