Heat exchanger with bypass valve

Abstract

A heat exchanger for cooling a liquid has an inlet and an outlet for a liquid to be cooled. A bypass is provided that bypasses the heat exchanger. A valve controls flow of liquid into the heat exchanger or into the bypass. The valve has a valve seat, a valve cone, and at least one spring made of a shape memory material. The at least one spring counteracts a liquid pressure existing in the inlet.

Claims

1. A heat exchanger unit for a liquid, comprising: a housing having a fluid inlet passage receiving fluid into the housing at a first end; a second end of the fluid inlet passage connected to an inlet chamber; a heat exchanger element having a fluid inlet opening connecting to the fluid inlet passage and a fluid outlet opening connecting to the fluid inlet passage for the liquid to be cooled; a valve arranged within the fluid inlet passage between said first and said second end of said fluid inlet passage, the valve positioned within the fluid inlet passage between the heat exchanger fluid inlet opening and fluid outlet opening such that the fluid inlet passage downstream of the valve forms a bypass as a straight line continuation of the inlet passage; the bypass fluidically connecting said fluid inlet opening with said fluid outlet opening and operable to bypass liquid around said heat exchanger element when the valve is open; the valve controlling a liquid stream through said heat exchanger element and through said bypass, wherein the valve opens and closes flow through said bypass, wherein said valve comprises a valve seat; a valve cone operable to close on said valve seat; at least one spring comprised of a shape memory material providing a closing force to said valve cone urging said valve to close counteracting the liquid pressure in an inlet passage of the heat exchanger unit; wherein, in a first operating state at liquid temperatures above a limit temperature, the valve is closed at normal operating pressure, closing off flow in the bypass, the valve configured to open in response to elevated liquid pressure to bypass liquid from the inlet passage to the inlet chamber by bypassing flow around the heat exchanger; wherein pressure at which the valve opens increases as the liquid temperature increases to the limit temperature, due to temperature dependent mechanical properties of the shape memory material of the at least one spring; wherein in a second operating state with the liquid temperature below the limit temperature, the valve is open at normal operating pressure, bypassing flow around the heat exchanger; wherein said shape memory material of said at least one spring exhibits a change of mechanical properties in the range of 60 to 100 degrees C.; wherein below the limit temperature of approximately 60 to 100 degrees C. said at least one spring has a spring constant and closing force providing said valve with an opening pressure of approximately 0 to 0.4 bar; wherein above the limit temperature of approximately 60 to 100 degrees C. said at least one spring has a different spring constant and closing force providing said valve with an opening pressure of at least 0.4 bar.

2. The heat exchanger unit according to claim 1, further comprising: a filter insert including a filter element, said filter insert received into said housing; wherein said filter insert comprises a lower terminal disk; and a non-return diaphragm arranged at said lower terminal disk and sealing against an interior of said housing; wherein said non-return diaphragm divides a dirty side of said filter into the inlet chamber; and an annular chamber; wherein said annular chamber surrounds said filter element; wherein a return flow from said annular chamber into said inlet chamber is prevented; and wherein said inlet passage fluidically connects said fluid inlet opening of said heat exchanger element; and wherein said bypass fluidically connects said inlet passage to said inlet chamber.

3. The heat exchanger unit according to claim 1, wherein said valve is arranged within said bypass; wherein said valve is configured as a one-piece unit, inserted into an open end of said bypass in a completely assembled state.

4. The heat exchanger unit according to claim 1, comprising: a filter insert including a filter element, said filter insert arranged within said housing; wherein said filter element has a dirty side and said dirty side communicates with said fluid outlet opening of said heat exchanger element; wherein said bypass fluidically connects said dirty side to said fluid inlet opening.

5. The heat exchanger unit according to claim 1, comprising: a filter insert including a filter element, said filter insert arranged within said housing; wherein said filter element has a dirty side and said dirty side communicates with said fluid outlet opening; wherein said bypass fluidically connects said fluid inlet opening of said heat exchanger element to said fluid outlet opening by bypassing the heat exchanger.

6. The heat exchanger unit according to claim 1, wherein a restoring force for said at least one spring of shape memory material is provided by said liquid pressure of the liquid.

7. The heat exchanger unit according to claim 1, wherein said at least one spring of shape memory material has an intrinsic two-way effect.

8. The heat exchanger unit according to claim 1, wherein said at least one spring of shape memory material is the only spring of said valve controlling said flow of liquid into said bypass.

9. The heat exchanger unit according to claim 2, wherein wherein said valve is configured as a one-piece unit, inserted into an open end of said bypass in a completely assembled state; wherein said bypass having said valve is arranged within said inlet passage; and wherein said bypass with said valve arranged therein is a straight continuation of said inlet passage.

10. The heat exchanger unit according to claim 9, wherein wherein said bypass is parallel to a main axis of said filter insert; and wherein an open end of said bypass is oriented in a direction towards a lid of said housing.

11. The heat exchanger unit according to claim 9, wherein said filter insert comprises a central tube that connects a clean side of said filter element with an outlet passage of said housing; wherein said central tube has an axial projection that extends axially outwardly past said lower terminal disk; wherein said axial projection penetrates said inlet chamber and is connected seal-tightly to said outlet passage of said housing.

12. The heat exchanger unit according to claim 11, wherein said axial projection has at the end facing said outlet passage a first and a second radial seals; a radial outlet opening provided between sad first and second radial seals through which the fluid after passing through said filter element flows into said outlet passage; wherein said first seal separates said inlet chamber from said outlet passage; wherein said axial projection in an area adjoining said radial outlet opening is configured as a closure plug that closes off an oil drain passage of said filter.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The accompanying Figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views and which together with the detailed description below are incorporated in and form part of the specification, serve to further illustrate various embodiments and to explain various principles and advantages all in accordance with the present invention.

(2) Features of the present invention, which are believed to be novel, are set forth in the drawings and more particularly in the appended claims. The invention, together with the further objects and advantages thereof, may be best understood with reference to the following description, taken in conjunction with the accompanying drawings. The drawings show a form of the invention that is presently preferred; however, the invention is not limited to the precise arrangement shown in the drawings.

(3) FIG. 1 discloses a section of a heat exchanger unit that can be connected by a flange to an engine block of an internal combustion engine for filtering and cooling oil;

(4) FIG. 2 discloses a section of the valve with a spring of shape memory material for use in a bypass of a heat exchanger according to the invention;

(5) FIG. 3 shows schematically and in an exemplary fashion the expansion course of a trained material as well as the length of a spring comprised thereof with two-way shape memory behavior. The illustrated behavior can be used for a valve that closes in the pulling direction (tension) of the spring;

(6) FIG. 4 shows schematically and in an exemplary fashion the expansion course of another trained material as well as the length of a spring comprised thereof with two-way shape memory behavior. The illustrated behavior can be used for a valve that closes in the pressure direction (resisting compression) of the spring;

(7) FIG. 5 shows schematically two valve variants with springs of shape memory material. On the left side, a valve is illustrated that closes in the pressure direction of the spring; on the right side, a valve that closes in the pulling direction of the spring is illustrated;

(8) FIG. 6 shows a section view of an embodiment of a heat exchanger unit in accordance with the present invention; and

(9) FIG. 7 shows another section view of the embodiment of a heat exchanger unit according to the invention.

(10) Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.

DETAILED DESCRIPTION

(11) Before describing in detail embodiments that are in accordance with the present invention, it should be observed that the embodiments reside primarily in combinations of method steps and apparatus components related to a heat exchanger for liquid including a shape memory actuated valve in stalled to enable pressure or temperature responsive bypass of the exchanger. Accordingly, the apparatus components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.

(12) In this document, relational terms such as first and second, top and bottom, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms comprises, comprising, or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by comprises . . . a does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

(13) FIG. 1 shows a heat exchanger unit 1 serving for cooling and filtering a lubricating oil in an internal combustion engine. It comprises a liquid filter 2 and a heat exchanger 3, wherein the liquid filter 2 and the heat exchanger 3 may be embodied as individual components but are fixedly connected to one another. The filter may be arranged also outside of the heat exchanger unit and may be connected to it by means of the liquid circulation. In the embodiment illustrated in FIG. 1 the liquid filter 2 has a filter element 5 arranged in a filter housing 4 and embodied as a hollow cylindrical element whose radial exterior side is the dirty side 6 with radial intake of the raw liquid to be filtered and whose cylindrical inner space is the clean side 7 from where filtered liquid is axially discharged. The filter element 5 is inserted into a receptacle in the filter housing 4 wherein the cylindrical interior of the filter element is placed onto a housing socket 8 that is part of a discharge tube for discharging the filtered liquid in the direction of arrow 9.

(14) The dirty liquid to be filtered is supplied in the direction of arrow 10 into a supply passage 11 integrally formed in the filter housing 4 in which a check valve 12 is arranged for preventing undesirable return flow of the liquid to be filtered in a direction opposite to the direction of arrow 10. The supply passage 11 communicates with an inlet opening 13 in the housing of the heat exchanger 3 arranged laterally on the filter housing 4. In regular operation, above a switching or limit temperature of the liquid, the liquid to be filtered flows through the supply passage 11 and through the inlet opening 13 into the heat exchanger 3, is cooled therein, and flows subsequently through the outlet opening 14 in the housing of the heat exchanger 3 and a connecting passage 15 in the filter housing into the outer annular space that surrounds the filter element 5 and impinges radially on the dirty side 6 of the filter element. After having radially passed the filter element, the filtered and cooled liquid is discharged via the clean side 7 and the housing socket 8 in direction of arrow 9.

(15) According to FIGS. 1 and 2 the supply passage 11 is connected by a bypass 16, that is provided in the wall of the filter housing and is positioned opposite the inlet opening 13 into the heat exchanger 3, immediately with the annular space that surrounds the filter element 5 as well as the dirty side 6 of the filter element. The bypass opening is to be closed and opened by a valve 17 that is arranged in the area of the supply passage 11, wherein the valve 17 comprises a spring of shape memory material 18 that when a switching temperature is surpassed or undershot changes its mechanical properties.

(16) In FIG. 2, the valve (corresponding to valve 17 in the filter housing 4 according to FIG. 1) is shown in its open position. This spring of shape memory material 18 is clamped between valve cone 22 and valve hood 24 wherein the valve hood 24 is provided with penetrations 25 through which the oil can flow out. The liquid flow that enters through the inlet passage 11 is guided immediately in the direction of arrow 23 via the bypass 16 to the dirty side 6 of the filter element 5 by bypassing the heat exchanger 3. Below a specific switching temperature, which in case of oil filtration or oil cooling is approximately 80 degrees C., the spring of shape memory material 18 is in its cold shape. The spring 18 is designed such that in this state it is so strongly tensioned that a minimal pressure of the valve cone 22 on the valve seat 21 is generated. The valve has in this state a minimal opening pressure. In this connection, the regular liquid pressure in operation of the internal combustion engine in the cold state is sufficient for opening the valve. In this way, it can be prevented that the increased viscosity at low temperatures of the liquid to be filtered causes blockage and clogging of the heat exchanger 3. Upon surpassing the switching temperature, the microstructure of the spring 18 of shape memory material changes so that its length in the unloaded state would become greater. As a result of clamping of the spring 18 in the valve 17 and the resulting predetermined length, a higher pretension of the spring is however generated so that the spring force and thus the opening pressure of the valve will increase. Upon overpressure in the inlet passage 11 the closure force of the valve is however overcome. In this way, the bypass 16 at liquid temperatures above the switching temperature and at normal pressure conditions is closed so that the entire liquid flow is guided via the inlet opening 13 through the heat exchanger 3. At liquid temperatures below the switching temperature and normal pressure conditions the bypass is however open; likewise, at liquid temperatures above the switching temperature and simultaneous pressure peaks of the oil pump in the inlet passage 11 it is also open.

(17) FIGS. 6 and 7 show different section views of an embodiment of a heat exchanger unit 101 according to the invention. The heat exchanger unit 101 comprises a connecting flange 142 in which an inlet passage 111 is arranged through which the fluid to be purified and cooled enters the heat exchanger unit. From the inlet passage 111 the inlet opening 113 branches off toward the heat exchanger element 103. From it the fluid flows through the outlet opening 115 into the inlet chamber 106a. Downstream of the inlet opening 113 a bypass 116 is connected to the inlet passage 111 and in an advantageous embodiment as shown in FIG. 6 is a straight continuation of the inlet passage 111. The bypass 116 connects, by bypassing the heat exchanger element, the inlet passage 111 to the inlet chamber 106a. A valve 117 is arranged in the bypass 116; it comprises a single spring 118. The spring 118 is comprised of a shape memory material with intrinsic two-way effect. Upon passing through the limit temperature range at approximately 80+/10 degrees C. the microstructure of the spring 118 changes and thus the spring constant and the opening pressure of the valve 117. The valve 117 is designed such that for fluid temperatures below the limit temperature range the opening pressure of the valve is in the range of a few tenths of a bar, in particular 0 to 0.5 bar. Accordingly, in this state the bypass 116 in operation is continuously flown through. At the same time, the heat exchanger element is also flown through. In this way, in the cold state the flow resistance of the arrangement is minimized. In the hot state, above the limit temperature range, the spring 118 has a higher spring constant wherein the valve is designed such that the opening pressure is in the range of 1 to 3 bar, advantageously in the range of 2+/0.5 bar. The valve 117 thus acts in the hot state like a conventional radiator bypass valve.

(18) The bypass 116 extends parallel to the main axis of the filter insert 102. The opening of the bypass is advantageously oriented in the direction of the lid 141 of the filter housing 104. This has the advantage that the bypass together with the remainder of the interior that receives the filter insert can be demolded wherein the opening of the bypass is easily accessible. The valve 117 is thus, because of the generously sized opening, insertable into the filter housing in which also the filter insert is mounted. In this connection, the valve 117 is configured as a unit and insertable into the bypass in completely assembled state.

(19) The spring 114 is arranged on the intake side of the valve 117 and counteracts the liquid pressure existing thereat. The valve cone 145 rests on the valve seat 146 on the side opposite the spring 118 and has a projection that extends through the spring 114. The projection is connected on the side of the spring facing away from the valve seat to the spring, wherein the other end of the spring is supported on the valve seat 146. Accordingly, the spring 118 pulls the valve cone 145 opposite to the flow direction against the valve seat 146. The valve 117 is mounted in the bypass 116 in that it is pushed into the bypass. Because of the oversize of the valve seat 146 the valve is clamped tightly in the bypass 116.

(20) In the filter housing 104 a filter insert 102 is arranged that comprises a central tube 133 and a filter element 132. The filter element 132 is pushed onto the central tube 133 and, in the area of the terminal disks, is seal-tightly connected to the central tube 133. In FIG. 6 the filter element 132 is not illustrated; its position is indicated by a large X on either side of the central tube. The filter element 132 has at its lower terminal disk 131a non-return diaphragm 130 that prevents return flow of the liquid from the annular chamber 106b into the intake chamber 106a. At the end of the filter element 132 opposite the non-return diaphragm 130 the central tube 133 is provided with a pressure relief valve 135 that opens upon excess pressure in the annular chamber 106b, for example, in case the filter element 132 is clogged, and connects the annular chamber with the interior of the central tube 133. In case of overpressure in the system, in particular in the cold state with thick (example, viscous) lubricating liquid, the arrangement of the valves 117 and 135 and the non-return diaphragm 139 interact with one another in an advantageous manner. The valve 117 opens, and thus opens an additional flow cross-section parallel to the heat exchanger element so that in a first step the flow resistance is minimized. The subsequently flown-through non-return diaphragm 130 opens a large cross-section, in particular in comparison to a regular non-return valve, so that also at this location a minimal differential pressure is achieved. The filter element 132 that is flown through subsequently may generate in particular in case of cold thick lubricating liquid a great flow resistance that is reduced by the pressure relief valve 135 that opens for increased pressure. In addition to the fulfilled safety functions, the entire arrangement is thus also suitable, in particular in the cold state, to minimize the differential pressure of the entire system so that the emissions of an internal combustion engine that is provided with a heat exchanger unit may be reduced in the cold state, in particular when starting the engine in the cold state.

(21) The central tube 133 has an axial projection 136 that connects the clean side 107 of the filter element with the outlet passage 134 at the connecting flange 142. The axial projection 136 projects into a socket 143 from which the outlet passage 134 and oil drain passage 140 are branched off. In this connection, the axial projection comprises at its end two radial seals between which a radial outlet opening 137 is provided through which the cleaned fluid can flow into the outlet passage 134, wherein the first seal 139 separates the inlet space 106a from the outlet passage 134. The axial projection is embodied in the area adjoining the radial outlet opening 137 as a closure plug 138 with a second seal 144 that closes off the oil drain passage 140.

(22) The central tube 133 is connected to the lid 141 by a snap connection in such a way that the central tube 133 is rotatable relative to the lid 141. When the lid 141 that is connected by a screw connection to the filter housing 104 is opened, the central tube and the filter element 132 are released also at the same time. In this way, the lid 141, the central tube 133 and the filter element 132 can be removed as a unit.

(23) When the lid 141 is released first the closure plug 138 will open so that the lubricating liquid contained in the arrangement can drain into the oil drain passage. First the already cleaned lubricating liquid that is still contained in the central tube 133 will flow out. When the lid 141 is opened farther, the first seal 139 loses contact. Then, the lubricating liquid of the inlet chamber 106a and the annular chamber 106b can drain off as well as a part of the lubricating liquid from the heat exchanger element 103. The outlet opening 115 in an advantageous embodiment is as low as possible, i.e., positioned at a height as minimal as possible, so that a volume proportion as large as possible can drain from the exchange element.

(24) In an advantageous embodiment, the socket 143 in the area of the inlet chamber 106a has an opening that connects the interior of the socket 143 to the inlet chamber 106a (not shown here). In this way it is achieved that the inlet chamber 106a can drain completely even when the socket projects into the inlet chamber 106a.

(25) In the foregoing specification, specific embodiments of the present invention have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present invention. The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential features or elements of any or all the claims The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued.