Activator of pilot type fire protection systems and sytems using same

Abstract

An activator for a pilot type firefighting system for accelerating firefighting system activation is disclosed. The system comprises a control valve which acts to control firefighting fluid flow to a distribution system, and configured such that release of pressure to a control chamber would activate the control valve. The activator comprises a first chamber in fluid coupling to the pilot fluid and a second chamber in fluid coupling to the pilot line via a flow restrictor. A pressure sensing member is disposed such that pressure difference between the chambers would cause an activation of a switch. The release of the switch directly or indirectly causes activation of an electrical valve which vents the pressure in the control chamber. Several aspects of the invention include various firefighting arrangements, various optional features of the activator, firefighting system, and several methods of operation of a system utilizing the activator.

Claims

1. An electromechanical firefighting system activator comprising: a body defining an inner cavity; a pressure sensing member at least partially disposed within the cavity, the pressure sensing member dividing the cavity into a first and second chambers, at least a portion of the pressure sensing member being movable from a closed to an open state, responsive to pressure difference in the first and second chambers; a pilot fluid port being in fluid communication with the first chamber; the first and second chambers having a fluid coupling path therebetween, the fluid coupling path comprising a fluid flow restrictor disposed to control fluid flow from the first chamber and the second chamber, the restrictor has a smaller flow rate from the second chamber to the first chamber, than the flow rate enabled by the pilot fluid port from the first chamber; a switch actuation mechanism coupled to the pressure sensing member and movable responsive to the state of the pressure sensing member; a switch disposed to be actuated by the switch actuation mechanism.

2. The electromechanical activator as claimed in in claim 1, wherein the pressure sensing member is urged to an open state when the pressure in the first chamber is lower than the pressure in the second chamber.

3. The electromechanical activator as claimed in claim 1, further comprising a latch configured to directly or indirectly capture and maintain the pressure sensing member in the open state.

4. The electromechanical activator as claimed in claim 1, further comprising a switching latch configured to latch the switch into an activated state, subsequent to being activated by the switch actuation mechanism.

5. The electromechanical activator as claimed in claim 4, wherein the switching latch is selected from a mechanical latch, an electrical latch, an electromechanical latch, an electronic latch, a magnetic latch, and any combination thereof.

6. The electromechanical activator as claimed in claim 4, wherein the switching latch is operationally separable from the switch actuation mechanism.

7. The electromechanical activator as claimed in claim 4, wherein the switch actuating mechanism is configured to move a latch holding the switch in one state during standby state, away from the switch, allowing the switch to move to an activated state.

8. The electromechanical activator as claimed in claim 1, wherein the pressure sensing member is a diaphragm.

9. The electromechanical activator as claimed in claim 1, wherein the switch actuating mechanism comprises a rod coupled to the pressure sensing member.

10. The electromechanical activator as claimed in claim 9, further comprising a latch configured to capture the rod.

11. The electromechanical activator as claimed in claim 1, further comprising a sealing port in fluid communications with the first chamber, and a seal coupled to the pressure sensing member, the seal being operative to impede fluid flow via the sealing port when the pressure sensing member is in a closed state and allow fluid communications via the sealing port when the pressure sensing member is in the open state.

12. The electromechanical activator as claimed in claim 1, wherein the flow restrictor is at least partially disposed within the pressure sensing member.

13. The electromechanical activator as claimed in claim 1, wherein the flow restrictor comprises a check valve configured to allow fluid flow from the first chamber to the second chamber and impede fluid flow from the second chamber to the first chamber.

14. The electromechanical activator as claimed in claim 13, wherein the check valve is constructed to leak, so as to provide unequal fluid flow in each direction between the two chambers.

15. The electromechanical activator as claimed in claim 1, wherein the flow restrictor may be disposed in the body or externally to the body.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The summary above, and the following detailed description will be better understood in view of the enclosed drawings which depict details of preferred embodiments. It should however be noted that the invention is not limited to the precise arrangement shown in the drawings and that the drawings are provided merely as examples to facilitate understanding of different aspects of the invention.

(2) FIG. 1 depicts schematically a common pilot type firefighting system in accordance with the prior art.

(3) FIG. 2 depicts schematically a cross-section of a firefighting system activator shown in a closed state.

(4) FIG. 3 schematically a cross-section of the firefighting system activator of FIG. 2 shown in an open state.

(5) FIGS. 4A-E depict schematically several optional features of the activator.

(6) FIG. 5 depicts schematically a pilot type firefighting system embodying an aspect of the present invention.

(7) FIG. 6 depicts schematically yet another pilot type firefighting system embodying an aspect of the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

(8) Aspects of the activator is explained in the context of a firefighting system. By way of example FIGS. 5 and 6 depict schematically simplified firefighting system arrangements incorporating an activator 200.

(9) FIG. 2 depicts schematically, a cross-section of a firefighting system activator in accordance with an aspect of the present invention.

(10) Pilot line 45 is coupled to the activator 200 via pilot port 330.

(11) The activator 200 comprises a body 205 defining a chamber divided into a first and a second chambers, termed an immediate chamber 305 and delay chamber 310. The immediate and delay chambers are mutually separated by a pressure sensing member such as a diaphragm 315. The pressure sensing member 315 is exposed on one side to pressure in the immediate chamber 305, and on the opposite side to pressure in the delay chamber 310. The pressure sensing member 315 is configured to be movable between at least a closed and an opened state. FIG. 2 depicts the pressure sensing member 315 in a closed state, while FIG. 3 depicts it in one of the plurality of potential open states.

(12) The immediate 305 and the delay 310 chambers are in fluid coupling via a flow restrictor 345. When the firefighting system is in standby state the immediate 305 and delay 310 chamber are subject to the same pressure as the pressure has been equalized via the flow restrictor. When changes in the pilot pressure occur slowly, over extended periods of time the pressure is equalized via the flow restrictor. At standby state the pressure sensing member 315 is urged to the closed state by static forces, such as the resilient shape of a diaphragm embodying the pressure sensing member, a spring, differing areas exposed to the pressure in both chambers, and the like. However, when the pressure in the pilot line 45 is reduced the pressure in the immediate chamber 305 is reduced at a faster rate than the pressure in the delay chamber 310, due to the limited flow which is allowed by the flow restrictor 345. Thus a pressure difference is formed between the immediate chamber and the delay chamber, and the pressure sensing member is urged to an open state.

(13) A switch 335 is disposed such a transition of the pressure sensing member from the closed state to an open state urge the switch to activate. The switch may be a normally open or normally closed type, and in certain cases may be magnetic, resistive or capacitive, and the like, however the switch has at least two states, one which is recognized as standby state and the other as activated state, wherein while the switch is in the activated state electrical circuitry would cause activation of the control valve 10, where otherwise the switch is in a standby state. Stated differently, the switch 335 is activated by the transition of the pressure sensing member 315 to an open state, and any state which does not causes such activation of the control valve is considered to be a standby state. The switch may be activated directly or indirectly by the pressure sensing member. FIGS. 2-3 depict embodiments where the switch is activated by a rod 325 coupled to the pressure sensing member 315. In some embodiments the rod has an expanded section 340 which activates the switch 335. As may be seen in FIG. 3, the expanded section pushes an activation arm of the switch. The rod 325 and the expanded section 340 act as a switch activation mechanism. It is noted that other switch activation mechanisms may be utilized, including optional varying mechanical linkages which may be utilized to activate the switch 335 in response to the state of the pressure sensing member. In certain embodiments the pressure sensing member itself acts as the switch actuation mechanism, and the switch is coupled directly thereto. In such embodiments the pressure sensing member or the portion thereof that activates the switch should be construed to embed therein the switch actuating mechanism.

(14) Furthermore, the switch may be implemented in a variety of manners. By way of example the switch may be magnetic such as a reed switch, or a magnetically responsive sensor or contact. The switch may also be capacitive, ultrasonic, optical and the like, as will be clear to the person skilled in the art.

(15) In certain embodiments flow restrictor 345 is implemented as an orifice in the pressure sensing member 315. In other embodiments, as shown by way of example in FIG. 4C, the flow restrictor 345 is external to the activator 200, and in certain other embodiments the flow restrictor is embodied in a passage within the body 205 as shown for example in FIG. 2, enumerated as 350A. One or more flow restrictor passages may be utilized, and the passages may differ in type and/or location. The skilled in the art would recognize many arrangements that would enable a restricted fluid communications from the delay and immediate chambers.

(16) FIG. 3 depict an embodiment in which the flow restrictor 345 comprises an elongated narrow tube 350 extending upwardly into the delay chamber, and in some such embodiments the tube is bent at its upper portion. Such arrangement enhances the reliability of the activator as it reduces the risk of clogged flow restrictor. In certain embodiments which use the tube, the tube itself may act as a flow restrictor, or an orifice may be disposed at its opening or along its length. In certain embodiments, such as shown by way of example in FIGS. 4A and 4B, a check valve 350B allows fluid communication from the immediate chamber to the delay chamber, while impeding or blocking fluid communication from the intermediate chamber to the delay chamber. The check valve may be disposed at any convenient location where it may affect its function.

(17) Certain embodiments provide the immediate chamber with a sealing port 326. In standby state seal 327 seals the sealing port 326 and isolates the immediate chamber 305 from the optional activator output port 347. While the activator is in an activated state, seal 327 is displaced and allows pilot fluid to flow from pilot port 330 to the activator output port 347 via the sealing port 326.

(18) During system standby state, the pressure in the delay chamber 310 substantially equals the pressure in the immediate chamber 305, which in turn equals the pilot pressure Pp. A sensor 55 such as a sprinkler is coupled to the pilot line 45 and is operative to vent the pilot line when activated in response to fire or excessive heat detection. Venting the pilot line causes a drop in the pilot pressure. Thus the pressure in the immediate chamber 305 drops as well. However due to the flow restrictor 350, the pressure in the delay chamber stays at or close to the pilot pressure Pp before the sensor activation for a certain time period. Thus the pressure at the delay chamber urges the pressure sensing member 315 to an open state which moves the seal 327 to permit flow of pilot fluid from the activator pilot port 335 to the accelerator output port 347. Output port may simply be the sealing port which vents directly to the ambient environment, or may be embodied as a separate port, allowing controlled connection thereto. The transition of pressure sensing member 315 to the open state brings the activator to an activated, i.e. open, state. It is noted that if a pressure source 50 is coupled to the pilot line and is operative, the sensor 55 is dimensioned to vent pressure from the pilot line at greater rate than the rate at which the pressure source would replenish it.

(19) FIG. 2 depicts an activator at standby state, while FIG. 3 depicts an activator at an activated state. As rod 325 is coupled to the pressure sensing member 315, it moves downward when the latter transitions to an open state. The expanded section 340 of the rod 325 is pushed against the switch 335 causing the switch to transition to an activated state.

(20) Operationally, activation of the switch is presumed to be due to detection of a fire event, and thus it is desired to maintain the switch activated, until intentionally reset. To that end an optional switching latch is provided. Certain embodiments utilize electrical or electromechanical latching, such as a flip-flop, a relay, electronic latching.

(21) FIGS. 2 and 3 depict a mechanical latching arrangement where the rod has a latching expanded section 380. A latch 375 is urged against the rod 325 or its expanded section by spring 370. The latch has a hole cut thereto, which is sufficiently large to allow the latching expanded section therethrough. Once the rod is pushed downward during the transition of the activator to an activated state, the latch 375 is urged by spring 370 to a locked position, i.e. to the left in the depicted drawing. When in the locked position it holds the latching expanded section 380 against moving back up, thus maintaining the switch in the activated position. Pushing the latch 375 against the spring would allow the rod to move up, allowing the pressure sensing member into the closed state, and such upward movement would release the switch 335.

(22) Notably similar latching results may be obtained by a narrowing in the rod, and the like, as will be clear to the skilled in the art.

(23) Other switching latches may be utilized alone or in combination. By way of example, an electrical solenoid or relay may hold the switch or a secondary switch. An electronic circuit may such as a flip-flop, other logic, or sample and hold circuits may be utilized to provide a switching latch. An electromechanical mechanism may be utilized to activate a mechanical latch. A magnetic device may be utilized to hold the switch activated once it was activated, and the like. In certain embodiments the latching mechanism is separate from the actuator, such as by way of example when logic is utilized at a control panel to affect the latching. Other latching arrangements are envisioned, such as hydraulic latching of the actuator or other firefighting components. By way of example a control valve may be arranged in a latching arrangement, wherein once activated it will maintain the activated state until deliberately reset.

(24) FIG. 3 depicts an optional orifice seal 352. In order to reduce the risk of a clogged flow restrictor 345 and to provide better immunity to pressure fluctuations after activation, an orifice seal or plug may be utilized. The orifice seal 352 is disposed such that when the pressure sensing member 315 is in the activated state the orifice seal prevents or further limits fluid flow between the immediate and delay chambers. Such arrangement would tend to act somewhat similar to a latch, and provide protection to the flow restrictor 345. It is noted that with proper design, the higher the pressure difference between the immediate and delay chamber, the tighter the seal would tend to block fluid flow therebetween. The skilled in the art would recognize that the orifice latch may be embodied in many other forms than the simplified schematic form depicted.

(25) FIG. 4A depicts yet another embodiment of the activator, showing two optional features which differ from the embodiments of FIGS. 2 and 3. The first difference is the inclusion of a check valve 350B, which allows pilot fluid to flow from the immediate chamber 305 to the delay chamber but impedes the pilot fluid in the delay chamber from flowing back to the immediate chamber. The check valve acts as the flow restrictor 345 or the passage 350A in other embodiments. It is generally desired that such check valve would be made intentionally to leak, thus presenting a high flow resistance to backflow of fluid from the delay to the intermediate chamber. As the pressure in the pilot changes due to temperature, minor leaks, and the like, a check valve which completely seal the backflow would cause trapping of the highest pressure experienced in the system at the delay chamber, which may result in false activation when the pressure in the immediate chamber drops slowly due to such reasons as described above.

(26) FIG. 4A also depicts an optional switch activation and latching mechanism. When the pressure sensing member moves to the open position it pushes the rod 325, which in turn pushes a switch cap 385 onto a switch, thus activating it. The switch cap may take any desired shape, including a sleeve, a cylinder, a properly dimensioned loop, and the like, dimensioned such that when pushed the rod 325 it would activate the switch 335. The movement of the switch cap may be obstructed by a resilient obstruction 336 such as a spring, a plunger, a handle, and the like, or be dimensioned such that the pushing the cap thereupon requires a certain force, to prevent nuisance tripping. In certain embodiments the obstruction is utilized to activate the switch, while in others a different portion of the switch cap is utilized for that purpose. The force exerted by the rod 325 is sufficient to cause the switch cap to be pushed and activate the switch. Preferably the switch cap would encircle the switch. FIG. 4B depicts the activator at an activated state with the pressure sensing member and the rod pushing the switch cap onto the switch, compressing the resilient obstruction 336 and activating the switch.

(27) Latching of the switch may be achieved by allowing the switch cap 385 to disengage from the rod 325. Therefore the switch cap would remain holding the switch engaged after it was pushed thereon by the rod. FIG. 4C depicts the activator after the rod and the pressure sensing member have been retracted from the switch cap, which remains coupled to the switch and maintaining the switch activated.

(28) The switch arrangement may take various arrangements. By way of example the switch cap may be a magnet disposed so as to be pushed into a sensor, and optionally stay within the range of the sensor because it is not permanently attached to the rod (Not shown).

(29) FIG. 4C also depicts an optional arrangement for controlling pilot fluid flow between the immediate and delay chambers utilizing an external flow restrictor. In this exemplary embodiment the flow restrictor 345 is disposed externally to the activator body 205, and being in fluid coupling to the pilot line 45 on one side, and via line 390 to the delay chamber. It is noted that the flow restrictor 345 may be coupled directly between the immediate and delay chambers.

(30) FIGS. 4D and 4E represents the section marked by the segmented circle DET of FIG. 4C, however these figures depict a different example of the latching arrangement than the one shown in other figures. In this embodiment the latch comprises a retainer 386A which during standby state is located about the switch, maintaining it in the standby state, as seen in FIG. 4D. FIG. 4E depicts the latching arrangement after activation of the activator, and with rod being retracted. During activation, the retainer 386A is pushed downwards by pusher 386. Pusher 386 is dimensioned to allow the switch to transition to the active state while the pusher pushes retainer 386A away from maintaining the switch in a non-active state. Such dimensioning may by way of example be achieved by a slot which will allow the switch to be activated. If the activator transitions back to the non-activated state, switch is still activated until the retainer is relocated to maintain the switch in inactive state.

(31) FIG. 5 depicts a simplified schematic of a firefighting system utilizing the present activator. It is noted that large portions of the firefighting system of FIGS. 5 and 6 are similar to the system depicted in FIG. 1, however the system of FIGS. 5 and 6 are improved by the present activator, which makes certain components of the older system redundant. Similar to FIG. 1 primary firefighting fluid is supplied under pressure Pw to a main pipe 2. By way of example such fluid may be from public water supply, a dedicated reservoir, a dedicated firefighting water supply, a gaseous fluid, foam system and the like. The fluid is piped to a shutoff valve 5 which is normally open. A control valve 10 is coupled to the fluid supply downstream from the shutoff valve 5. A fluid distribution system 15 is coupled to the outlet of control valve 10. Fluid under pressure is also supplied to the control chamber 30 of control valve 10, as well as to control line 20, via flow restrictor 25. As explained above it is common to couple fluid from the primary fluid supply to the control chamber 30, however the pressure supplied to the control chamber Pc may come from any desired source. The shutoff valve 5 is commonly required by applicable standards, but may be omitted in certain systems, for example systems which incorporate the shutoff valve in the control valve. In the embodiment depicted in FIG. 5 the distribution system 15 is used as the pilot line system 45, and during standby state pilot pressure is kept by pressure source 50. In such embodiments the pilot line 45 is said to be embedded in the distribution system 15.

(32) The firefighting system depicted in FIGS. 5 and 6 vary from the system of FIG. 1 primarily by the use of activator 200 which replaces both the accelerator 60 and the actuator 35.

(33) Pilot pressure Pp is supplied from the pilot line 45 to the immediate chamber 305 of the activator 200 via the input port 330, and to the delay chamber via the flow restrictor. As explained above, when the sensor 55 activates and vents the pilot pressure to the ambient the pressure in the pilot line 45 is reduced, causing a pressure difference between the immediate and the delay chambers. As a result the pressure sensing moved to the open state, and asserts switch 335. In this simplified diagram a power source 393 is electrically coupled in series to the switch 335 and to a solenoid valve 400. The solenoid valve is coupled in fluid communications to control line 20 and dimensioned to cause a pressure drop in the control line, which in turn reduces the pressure in the control chamber 30 of control valve 10, causing the control valve to open and the firefighting fluid to be piped to the distribution system, and to suppress the fire. An optional alarm 90, represented by dashed lines may also be coupled to the switch 335. The solenoid valve in such embodiment should have lower flow resistance than flow restrictor 25.

(34) The switch may also be utilized to activate an optional alarm 90.

(35) It is important to reiterate that the depicted electrical portion of the system is highly simplified. Electronic devices, processors, relays, controllers and the like (not shown) may be deployed to provide optional system services, increase reliability, and otherwise entertain system and device features and limitations. By way of example electronic control panels are well known in firefighting systems. Such electronic panels, or dedicated logic, may be adapted to provide activation of the solenoid valve 400 as well as generates alarms and notifications as required. Additionally, in certain systems requiring two or more fire indications before the main firefighting fluid is released such panels or logic may be utilized to activate the solenoid valve only when all conditions are met.

(36) FIG. 6 depicts a firefighting system similar to the system of FIG. 5 however it differs therefrom by several optional features. While the firefighting system in FIG. 5 utilizes an integrated pilot and distribution system 45 and 15, the system of FIG. 6 utilizes a primary firefighting fluid distribution system 15 which may utilize sprinklers or open nozzles 56, and a separate pilot line 45 coupled to sensors 55.

(37) Yet another difference is the use of a logic 395 to activate the solenoid valve 400 in response to the activation of the activator switch 335. The logic 395 may activate the solenoid valve only in response to the activation of switch 335 or after a number of conditions have been met, such as after a predetermined delay, after a second detector indicates the presence of fire, and the like. The logic 395 may also activate different alarms 90, send notifications to interested parties such a firefighting personnel or organizations, and the like.

(38) Logic 395 may also act to electrically or electronically latch the switch. Such latching is well known in the electrical arts and be achieved by software, by a flip-flop arrangement, by a relay, by Silicon Controlled Switches (SCR's), triacs, and the like.

(39) Logic 395 may be implemented in numerous ways including inter alia various combinations of general purpose computer or controller, dedicated logic, field programmable logic, discrete gates, transistors, SCR's, and other discrete electronic components, electromechanical relays and the like. The logic may comprise analog and/or logic components. Numerous construction methods and components would be clear to the skilled person coming to implement the logic, once the design requirements are defined.

(40) FIG. 6 further depicts an optional hydraulic latch 398, coupled to the control line 20. The hydraulic latch is operative to prevent pressure buildup in the control chamber 30 once such pressure had been reduced below a certain level. Generally the latch comprise an inlet, and an outlet coupled fluid-wise to a chamber, and a shutoff member which prevents flow from the inlet to the outlet in closed state, and allows such flow when in open state. The shutoff member is urged to an open state by an opening mechanism such as a spring, gravitational pull, and the like. A closing mechanism is also provided, to manually or automatically urge the shutoff member to a closed state. Pressure in the chamber urges the closed shutoff member to remain in the closed state. Thus, in response to pressure in the chamber dropping below a certain level, the shutoff member opens and remains open under the urging of the opening mechanism, until the closing mechanism is activated. In an optional embodiment, the inlet of an hydraulic latch 398 is fluid-wise coupled to the control line 20, and thus, if the pressure in the control line drops below a certain level, the hydraulic latch opens, and will maintain the control line vented, preventing premature closing of the control valve 10.

(41) Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present invention. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. By way of example orifice type flow restrictors may be utilized where a check valve type restrictor is depicted, the flow restrictor location may be modified as internal to the activator or external thereto, and the like. Similarly while a passage of those teaching, and/or a drawing may depict a specific combination of latch, switch, pressure sensing member and flow restrictor, each of those components may be replaced by a different type of the component. By way of example an embodiment with a mechanically separable latch and a check valve type restrictor, may utilize an electrical latch in combination with the same check valve restrictor, and the like.

(42) The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms a, an, and the may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The disclosed embodiments do not preclude additional features, and are intended as illustrative examples, rather than as limiting details. When an element is referred to as being coupled to another element, it may be directly on, engaged, connected or coupled to the other element directly or by intervening elements unless the term directly coupled is used, where no intervening elements are present. As used herein, the term and/or includes any and all combinations of one or more of the associated listed items. The term fluid communication implies that fluid may flow between the two elements being in such communication, either directly or via a pipe, duct, conduit, valve, and the like, and does not require similar cross-section therebetween. Commonly such communication also exposes the two coupled devices in such communications to similar pressures, especially when the fluid is non-compressible.

(43) Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, such designations are only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as first, second, and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed above could be equivalently termed a second element, component, region, layer or section without departing from the teachings of the example embodiments. Spatially relative terms, such as inner, outer, beneath, below, lower, above, upper, and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures, or in or relative to a specified orientation of an embodiment or a portion thereof. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a first element is described as being beneath other elements or features than the other elements or features would be above the first element in the described orientation, but if the device is otherwise oriented the spatially relative descriptors used herein should be interpreted with respect to such orientation. Thus by way of example the term upper side of the pressure sensing member 315 relate to side facing the delay chamber 310, while the lower side, relate to opposite side, facing the immediate chamber 305, regardless of the actual orientation of the activator.

(44) It will be appreciated that the invention is not limited to what has been described hereinabove merely by way of example. While there have been described what are at present considered to be the preferred embodiments of this invention, it will be obvious to those skilled in the art that various other embodiments, changes, and modifications may be made therein without departing from the spirit or scope of this invention and that it is, therefore, aimed to cover all such changes and modifications as fall within the true spirit and scope of the invention, for which letters patent is applied.