Valves for regulating the fluid flow between a device, a heating device and a cooling device

Abstract

Valve (16) configured to direct the fluid flow (18) received by a device (12) to a heating device (15) and a cooling device (14) in a fluid circuit as a function of the fluid temperature, wherein the valve (16) comprises: a housing (20) defining a cavity (28) extending longitudinally between a first end and a second end, wherein the cavity (28) is configured to receive and discharge the fluid; a piston (22) arranged in the cavity (28) and movable longitudinally therein between a first position (34), a second position (36) and a third position (37), the piston (22) comprising a first part (44), a second part (46), a front part (48) and a rear part (56), the first part (44) being longitudinally spaced from the second part (46); the front part (48) serving as an intermediate part for connecting the first part (44) with the second part (46); the first part (44) and the second part (46) being radially dimensioned to fit into the cavity (28) so that the fluid (18) is prevented from passing through the cavity (28) between the first part (44) or the second part (46) and the housing (20);the front part (48) is radially dimensioned such that it is smaller than the first part (44) and the second part (46), so that a fluid flow (18) is permitted radially around the front part (48), between the front part (48), the first part (44), the second part (46) and the housing (20); the rear part (56) extends from the first part (46) opposite the front part (48), so that the first part (46) is arranged longitudinally between them; and the rear part (56) is radially dimensioned such that it is smaller than the first part (44); wherein the piston (22) defines a recess (80) that opens from the second part (46) and extends through the part (46), the front part (48) and the first part (44) and into the rear part (56), where the recess (80) terminates at an end wall (81); an actuator (24) which is functionally arranged in the cavity (28) and configured for continuous fluid communication with the fluid received by the device (12); wherein the actuator (24) is a coil spring having shape memory alloy material configured such that it is deactivated in response to the temperature of the fluid not being greater than a first temperature, so that the shape memory alloy material deactivates the actuator (24); wherein the shape memory alloy material is configured such that it is fully activated in response to the temperature of the fluid being at least equal to a second temperature, such that the full activation of the shape memory alloy material results in a full activation of the actuator (24); wherein the shape memory alloy material is configured such that it is partially activated in response to the temperature of the fluid being greater than the first temperature and less than the second temperature, so that the shape memory alloy material causes partial activation of the actuator (24); wherein the actuator (24) is configured to act continuously on the piston (22) when the actuator (24) is partially activated, so that the piston (22) moves into the second position (36); wherein the actuator (24) is configured to act continuously on the piston (22) when the actuator (24) is fully activated, so that the piston (22) moves into the third position (37); wherein a flow of fluid from the cavity (28) to the heating device (15) and from the heating device (15) to the device (12) is permitted when the piston (22) is in the first position (34); wherein the flow of fluid from the heating device (15) and the cooling device (14) is prevented when the piston (22) is in the second position (36); and wherein a flow of fluid from the cavity (28) to the cooling device (14) and from the cooling device (14) to the device (12) is permitted when the piston (22) is in the third position (37).

Description

[0001] The disclosure relates to valves for regulating the fluid flow between a device having, for example, an automatic transmission and a heating device and a cooling device.

[0002] For proper operation, a transmission for a vehicle or non-vehicle application, such as an HVAC system, requires a supply of fluid, such as conventional gear oil. This fluid can be used for functions such as cooling and lubrication. The lubrication and cooling capabilities of transmission oil systems greatly influence the reliability and durability of the transmission. Additionally, multi-speed power transmissions require fluid for controlled engagement and disengagement, at a desired schedule, of the various torque-transmitting mechanisms that operate to establish the gear ratios within the internal gear assembly.

[0003] DE 103 46 195 A1 discloses a thermostatic valve with a first and second expansion element connected in series, and two gate valves movable by means of the two expansion elements. The expansion elements comprise wax mixtures that enable suitable temperature-stroke characteristic operation.

[0004] Further prior art is described in DE 20 2014 103 290 U1.

[0005] The object of the invention is to provide valves with which it is possible to provide a simple and reliable regulation of the circulation of fluid between, for example, a device comprising an automatic transmission, a cooling device and a heating device.

[0006] The problem is solved by the subject matter of claims 1, 2, 3 and 4. Fig. 1 is a schematic diagram of a device fluid circuit of a vehicle having a device, a cooler, a heater, and a valve in a first position such that fluid flows from the device to the valve, from the valve to the heater, and from the heater to the device. Fig. 2 is a schematic diagram of the fluid circuit with the valve in a second position such that fluid flows from the device to the valve and the valve restricts fluid flow therethrough back to the device. Fig. 3 is a schematic diagram of the fluid circuit with the valve in a third position such that fluid flows from the device to the valve, from the valve to the cooling device, and from the cooling device to the device. Fig. 4 is a schematic sectional view of a first embodiment of the valve in the fluid circuit, showing the valve in the first position. Fig. Figure 5 is a schematic sectional view of the valve of Fig. 4 in the fluid circuit shown in the second position. Fig. Figure 6 is a schematic sectional view of the valve of Fig. 4 in the fluid circuit shown in the third position. Fig. Figure 7 is a schematic sectional view of a second embodiment of the valve in the fluid circuit, showing the valve in the first position. Fig. Figure 8 is a schematic sectional view of the valve of Fig. 7 in the fluid circuit shown in the second position. Fig. 9 is a schematic sectional view of the valve of Fig. 7 in the fluid circuit shown in the third position. Fig. 10 is a schematic sectional view of a third embodiment of the valve in the fluid circuit, showing the valve in the first position. Fig. 11 is a schematic sectional view of the valve of Fig. 10 in the fluid circuit shown in the second position. Fig. 12 is a schematic sectional view of the valve of Fig. 10 in the fluid circuit shown in the third position. Fig. 13 is a schematic sectional view of a fourth embodiment of the valve in the fluid circuit, showing the valve in the first position. Fig. 14 is a schematic sectional view of the valve of Fig. 13 in the fluid circuit shown in the second position. Fig. 15 is a schematic sectional view of the valve of Fig. 13 in the fluid circuit shown in the third position.

[0007] Referring to the figures, in which like reference numerals refer to like elements, an exemplary fluid circuit is shown in the Fig. 1-3, generally shown at 10. The transmission fluid circuit 10 includes a device 12, a cooler 14, a heater 15, and a valve 16. As explained in more detail below, the valve 16 is configured to regulate the circulation of a fluid 18 between the device 12, the cooler 14, and the heater 15. The device 12 may be a transmission, such as an automatic transmission for a vehicle 11, configured to receive and discharge the fluid 18. The fluid 18 may be automatic transmission fluid (ATF), and the like. Further, the device 12 may be incorporated in applications other than vehicles. For example, the device 12 may be incorporated into HVAC systems of buildings, ships, aircraft, appliances, and the like.

[0008] The fluid 18 present in the device 12 has a viscosity that changes as a function of temperature. At cold temperatures, the viscosity can be high, resulting in parasitic losses and reduced fuel economy, as long as the temperature of the fluid 18 is not greater than a desired operating temperature. With reference to Fig. 1, when the temperature of the fluid is less than the desired operating temperature, the valve 16 is in the first position 34, so that the valve 16 directs the flow of fluid 18 from the device 12 to the heater 15 and from the heater 15 to the device. The heater 15 heats the fluid 18 to the desired operating temperature and directs the heated fluid 18 to the device 12. The heater 15 may be a heat exchanger, an electric heater, an oil / engine coolant heat exchanger, and the like.

[0009] The cooling device 14 may be an automatic device fluid cooling device 14 and the like. With reference to Fig. 3, the valve 16 is in the third position 37, so that the cooling device 14 receives the fluid 18 from the valve 16, cools the fluid 18, and discharges the cooled fluid 18, which ultimately flows back to the device 12. It should be noted that for simplicity, the figure shows the fluid 18 flowing directly to the device 12 after exiting the heating device 15 or the cooling device 14. However, one skilled in the art will recognize that the fluid 18 may flow through other components before returning to the device 12.

[0010] With reference to the Fig. 1 - 3, the valve 16, 116, 216, 316 is movable between three positions, i.e., a first position 34, a second position 36, and a third position 37. In order to heat the fluid 18 of the device 12 during operation, the valve 16, 116, 216, 316 is in the first position 34 and is configured to direct the flow of the fluid 18 from the device 12 to the heater 15 and from the heater 15 to the device 12 when the temperature of the fluid 18 delivered by the device 12 is not greater than a first temperature ( Fig. 1). However, when the fluid 18 delivered from the device 12 is at an intermediate temperature that is greater than the first temperature but less than a second temperature, the valve 16, 116, 216, 316 is in the second position 36 and can prevent or restrict delivery of the fluid 18 from the valve 16, 116, 216, 316 to the device ( Fig. 2). Also, in order to cool the fluid 18 of the device 12 during operation, when the temperature of the fluid 18 discharged from the device 12 is at least equal to the second temperature, the valve 16, 116, 216, 316 is in the third position 37 and is configured to direct the fluid flow 18 from the device 12 to the cooling device 14 and from the cooling device 14 to the device 12 ( Fig. 3). Therefore, the heater 15 only operates when the temperature of the fluid 18 is not greater than the first temperature, and the cooler 14 only operates when the temperature of the fluid 18 is at least equal to the second temperature, resulting in vehicle energy savings by preventing unnecessary operation of the heater 15 or the cooler 14 at temperatures greater than the first fluid temperature and less than the second fluid temperature. By way of non-limiting example, the first temperature may be 90 degrees Celsius (°C), and the second temperature may be 105°C. It should be noted that the valve may be configured to move between positions in response to other temperatures as well.

[0011] Generally referring to the Fig. 4-15, the respective valves 16, 116, 216, 316 each comprise a housing 20, a piston 22, an actuator 24, and a biasing device 26. The housing 20 defines a cavity 28 extending longitudinally between a first end 30 and a second end 32. The cavity 28 is configured to receive and discharge the fluid 18. The piston 22 is disposed in the cavity 28 and is longitudinally movable therein between the first position 34 ( Fig. 4, Fig. 7, Fig. 10, Fig. 13), the second position 36 ( Fig. 5, Fig. 8, Fig. 11, Fig. 14) and the third position 37 ( Fig. 6, Fig. 9, Fig. 12, Fig. 15). The fluid flow 18 from the device 12 to the cavity 28, from the cavity 28 to the heater 15 and from the heater 15 to the device 12 is permitted when the piston 22 is in the first position 34. Referring again to the Fig. 5, Fig. 8, Fig. 11, Fig. 14, a fluid flow 18 from the device 12 is permitted to the cavity 28, where the piston 22 may restrict, block, or otherwise prevent the fluid 18 from exiting the valve 16 when the piston 22 is in the second position 36. Finally, referring again to the Fig. 6, Fig. 9, Fig. 12, Fig. 15 a fluid flow 18 from the device 12 to the cavity 28, from the cavity 28 to the cooling device 14 and from the cooling device 14 to the device 12 is permitted when the piston 22 is in the third position 37.

[0012] Referring again to the Fig. 1-3, a first fluid passage 17 is disposed between the housing 20 of the valve 16, 116, 216, 316 and the device 12 and is in fluid communication therewith. A second fluid passage 19 is disposed between the housing 20 of the valve 16, 116, 216, 316 and the device 12 and is in fluid communication therewith, wherein the heating device 15 is disposed in fluid communication with the second fluid passage 19. A third fluid passage 21 is disposed between the housing 20 and the device 12 and is in fluid communication therewith, wherein the cooling device 14 is disposed in fluid communication with the third fluid passage 21. The housing 20 defines a first inlet 58, a first outlet 62, and a second outlet 64, each in fluid communication with the cavity 28.Therefore, the first inlet 58 is in fluid communication with the first fluid passage 17, the first outlet 62 is in fluid communication with the second fluid passage 19, and the second outlet 64 is in fluid communication with the third fluid passage 21.

[0013] Referring again to the Fig. 4-15, the actuator 24 is arranged in the cavity 28 so as to be in fluid communication with the fluid 18. The actuator 24 comprises a smart material 40, which may be a shape memory alloy (SMA) material, configured to be deactivated, i.e., to be in a first state, in response to the temperature of the fluid 18 in the cavity 18 not being greater than the first temperature, such that the SMA material 40 does not activate the actuator 24 and the valve 16, 116, 216, 316 is in the first position 34 ( Fig. 4, Fig. 7, Fig. 10, Fig. 13). Furthermore, the SMA material 40 is configured to be partially activated, ie, in a second state, in response to the temperature of the fluid 18 in the cavity 28 being greater than the first temperature and less than the second temperature, such that the SMA material 40 is partially activated and the valve 16, 116, 216, 316 is in the second position 36 ( Fig. 5, Fig. 8, Fig. 11, Fig. 14). In addition, the SMA material 40 is configured to be fully activated, ie, in a third state, in response to the fluid 18 in the cavity being at least the second temperature, such that activation of the SMA material 40 activates the actuator 24 and the valve 16, 116, 216, 316 is in the third position ( Fig. 6, Fig. 9, Fig. 12, Fig. 15). The SMA material 40 exhibits temperature hysteresis in its phase transformations. The magnitude of the hysteresis is typically between five degrees and forty degrees Celsius (C). The specific magnitude of the hysteresis in a particular application is a function of various parameters, including the material formulation of the SMA material 40 and the strain state of the SMA material 40.

[0014] The SMA material 40 has a crystallographic phase that can change between austenite and martensite in response to contact with a temperature of at least the first temperature and a temperature below the second temperature, which is typically higher than the first temperature. As used herein, the terminology SMA refers to alloys that exhibit a shape memory effect. That is, the SMA material 40 can undergo a phase change from the solid state via molecular rearrangement to change between a martensite phase, i.e., "martensite," and an austenite phase, i.e., "austenite." Stated another way, the SMA material 40 can undergo a displacive transformation instead of a diffusional transformation to change between martensite and austenite. A displacive transformation is a structural change that occurs through the coordinated movement of atoms (or groups of atoms) relative to their neighbors.In general, the martensite phase is the comparatively lower-temperature phase and is often more ductile than the comparatively higher-temperature austenite phase. The temperature at which the shape memory alloy material begins to change from the austenite phase to the martensite phase is known as the martensite start temperature, M. s The temperature at which an SMA material 40 completes the transition from the austenite phase to the martensite phase is known as the martensite end temperature M f Similarly, when an SMA material 40 is heated, the temperature at which the SMA material 40 begins to change from the martensite phase to the austenite phase is known as the austenite start temperature A s The temperature at which the SMA material 40 completes the change from the martensite phase to the austenite phase is known as the austenite end temperature A f known.

[0015] Therefore, SMA material 40 can be characterized by a cold state, ie when a temperature of the SMA material 40 is below the martensite final temperature M f of the SMA material 40. Similarly, the SMA material 40 can also be characterized by a hot state, ie when the temperature of the SMA material 40 is above the austenite final temperature A f of the SMA material 40.

[0016] During operation, the SMA material 40 that is pre-strained or subjected to tensile stress can change its dimension upon changing its crystallographic phase, thereby converting thermal energy into mechanical energy. That is, the SMA material 40 can change its crystallographic phase from martensite to austenite and thereby contract dimensionally if it is pseudoplastically pre-strained to convert thermal energy into mechanical energy. Consequently, the SMA material 40 can change its crystallographic phase from austenite to martensite and, when subjected to tension, can thereby expand dimensionally.

[0017] "Pseudoplastically pre-strained" refers to stretching the SMA material 40 while in the martensite phase, such that the strain exhibited by the SMA material 40 under that loading condition is not fully recovered when the load is removed, where a purely elastic strain would be fully recovered. In the case of the SMA material 40, it is possible to load the material such that the elastic strain limit is exceeded and deformation occurs in the martensitic crystal structure of the material before the true plastic strain limit of the material 40 is exceeded.A strain of this type between these two limits is a pseudoplastic strain, so named because upon unloading it is evident that it has deformed plastically, but when heated to the point where the SMA material 40 transforms to its austenite phase, this strain can be restored, with the SMA material 40 returning to the original length observed before any load was applied.

[0018] The SMA material 40 may have any suitable composition. In particular, the SMA material 40 may comprise an element selected from the group consisting of cobalt, nickel, titanium, indium, manganese, iron, palladium, zinc, copper, silver, gold, cadmium, tin, silicon, platinum, gallium, and combinations thereof. For example, suitable SMA materials may include nickel-titanium-based alloys, nickel-aluminum-based alloys, nickel-gallium-based alloys, indium-titanium-based alloys, indium-cadmium-based alloys, nickel-cobalt-aluminum-based alloys, nickel-manganese-gallium-based alloys, copper-based alloys (e.g.,Copper-zinc alloys, copper-aluminum alloys, copper-gold alloys, and copper-tin alloys), gold-cadmium-based alloys, silver-cadmium-based alloys, manganese-copper-based alloys, iron-platinum-based alloys, iron-palladium-based alloys, and combinations thereof. The SMA material 40 may be binary, ternary, or of any higher order, provided the SMA material 40 exhibits a shape memory effect, e.g., a change in shape orientation, damping capacity, and the like.

[0019] In the Fig. 4 - 6 and 10 - 15, the SMA material 40 expands longitudinally upon activation. Similarly, in the embodiments shown in the Fig. 7 - 9, the SMA material 40 when activated in the longitudinal direction.

[0020] The actuator 24 is activated when the temperature of the fluid 18 is greater than the first temperature. When the actuator 24 is activated, the actuator 24 acts on the piston 22 to move the piston 22 from the first position 34, as shown in the Fig. 4, Fig. 7, Fig. 10, Fig. 13, into the second position 36, which is shown in the Fig. 5, Fig. 8, Fig. 11, Fig. 14. When the temperature of the fluid 18 increases to at least equal to the second temperature, the actuator 24 continues to act on the piston 22 to move the piston 22 from the second position 36 shown in the Fig. 5, Fig. 8, Fig. 11, Fig. 14, into the third position 37, which is shown in the Fig. 6, Fig. 9, Fig. 12, Fig. 15. Fluid flow 18 is permitted from the device 12 to the cavity 28 of the valve 16, 116, 216, 316, from the cavity 28 to the heater 15, and from the heater 15 to the device 12 when the piston 22 is in the first position 34. Fluid flow 18 is permitted from the device 12 to the cavity 28 of the valve 16, 116, 216, 316 when the piston 22 restricts or prevents exit of the fluid 18 from the valve 16, 116, 216, 316 through the first or second outlet 62, 64 when the piston 22 is in the second position 36. Likewise, fluid flow 18 is permitted from the device 12 to the cavity 28, from the cavity 28 to the cooling device 14, and from the cooling device 14 back to the device 12 when the piston 22 is in the third position 37, as shown in FIGS. Fig. 6, Fig. 9, Fig. 12, Fig. 15 is shown.

[0021] Reference is now made to the Fig. 4 - 6, wherein the valve 16 comprises a coil spring 42 comprising the SMA material 40 as the actuator 24. The piston 22 is arranged in the cavity 28 and is longitudinally movable therein between the first position 34 ( Fig. 4), the second position 36 ( Fig. 5) and the third position 37 ( Fig. 6) movable. The coil spring 42 is operatively disposed within the cavity 28 between the second end 32 of the housing 20 and the piston 22 and configured to act on the piston 22. The piston 22 includes a first portion 44, a second portion 46, a front portion 48, and a rear portion 56. The first portion 44 is longitudinally spaced from the second portion 46. The front portion 48 serves as an intermediate portion for connecting the first portion 44 to the second portion 46. The first portion 44 and the second portion 46 are radially sized to fit within the cavity 28 such that the fluid 18 is prevented from passing within the cavity 28 between the first portion 44 or the second portion 46 and the housing 20.The front part 48 is radially dimensioned to be smaller than the first part 44 and the second part 46 such that fluid flow 18 is permitted radially around the front part 48, between the front part 48, the first part 44, the second part 46, and the housing 20. The rear part 56 extends from the first part 46 opposite the front part 48 such that the first part 46 is longitudinally disposed therebetween. The rear part 56 is radially dimensioned to be smaller than the first part 44. The actuator 24 of the coil spring 42 is operatively disposed in the cavity 28 between the first part 44 opposite the front part 48 and the housing 20. The coil spring 42 is wrapped around the rear part 56 such that the coil spring 42 acts on a first wall 45 of the first part 44. The coil spring 42 is configured to act on the first part 44 and exert a first force 38 in a first longitudinal direction 76.

[0022] The biasing device 26 is operatively disposed within the cavity 28 and configured to act on the piston 22 in a second longitudinal direction 78 counter to the first force 38 exerted in the first longitudinal direction 76. More specifically, the biasing device 26 is operatively disposed for reaction between the piston 22 and the first end 30 of the housing 20. The piston 22 defines a recess 80 opening from the second portion 46 and extending through the portion 46, the front portion 48, and the first portion 44, and into a rear portion 56, where the recess 80 terminates at an end wall 81. The preloading device 26 may be operatively disposed in the recess 80 for reaction between the end wall 81 of the piston 22 and the first end 30 of the housing 20 and apply a second force 52 to the piston 22 in the second longitudinal direction 78 opposite the first longitudinal direction 76 of the first force 38 exerted by the actuator 24.The biasing device 26 may be a compression spring 50. Resetting the biasing device 26 in the recess 80 allows the valve 16 to have a compact size without sacrificing a desired amount of travel of the piston 22 within the cavity 28. The end wall 81 faces longitudinally opposite the direction of the first wall 45.

[0023] With continued reference to the Fig. 4-6, the piston 22 separates the cavity 28 into a first portion 70 and a second portion 72. The first portion 70 is defined between the first part 44, the rear portion 56, and the housing 20. The second portion 72 is defined between the first part 44, the second part 46, the front portion 48, and the housing 20. The first part 44 of the piston 22 defines a plurality of vent holes 60 open between the first portion 70 and the second portion 72 of the cavity 28 to provide fluid communication between the first portion 70 and the second portion 72. Therefore, the vent holes 60 allow flow of the fluid 18 in the first portion 70 of the cavity 28 into the second portion 72 of the cavity 28.

[0024] The first inlet 58 of the housing 20 of the valve 16 provides fluid communication from the device 12 through the first fluid passage 17 into the first portion 70 of the cavity 28 regardless of the position of the piston 22. The first outlet 62 provides fluid communication from the second portion 72 of the cavity 28 to the second fluid passage 19 and thus the heater 15 when the piston 22 is in the first position 34 ( Fig. 4). The second outlet 64 provides fluid communication from the second portion 72 of the cavity 28 to the third fluid passage 21 and thus the cooling device 14 when the piston 22 is in the third position 37 ( Fig. 6).

[0025] Furthermore, when the piston 22 is in the second position 36 ( Fig. 5) the first part 44 of the piston 22 blocks the first outlet 62, and the second part 46 of the piston 22 blocks the second outlet 64. Thus, when the piston 22 is in the second position 36, fluid 18 is restricted or prevented from flowing through the heating device 15 or the cooling device 14.

[0026] With continued reference to the Fig. 4 - 6, the actuator 24 of the coil spring 42 is arranged in the first section 70 of the cavity 28 and is also in fluid communication with the fluid 18 arranged in the first section 70 of the cavity 28.

[0027] Now specifically referring to Fig. 4, the temperature of the fluid 18 is not greater than the first temperature, and the SMA material 40 of the coil spring 42 is deactivated, so that the coil spring 42 is contracted longitudinally. Thus, the contracted coil spring 42 acts on the first part 44 of the piston 22 in the first longitudinal direction 76 with a first force 38, while the biasing device 26 acts on the end wall 81 of the rear part 56 of the piston 22 in a second longitudinal direction 78 opposite the first longitudinal direction 76 with a second force 52 that is greater than the first force 38 of the coil spring 42 to hold the piston 22 in the first position 34. In the first position 34, the fluid 18 flows sequentially through the first inlet 58 into the first portion 70 of the cavity 28, through the vent holes 60, and into the second portion 72 of the cavity 28.The fluid 18 then exits into the second portion 72 of the cavity 28 by flowing through the first outlet 62 into the second fluid passage 19 to enter the heater 15. The fluid 18 then flows out of the heater 15 and into the device 12. It should be noted that in the first position 34, flow of the fluid 18 out of the cavity 28 and into the fluid cooling device 14 is prevented. Additionally, the actuator 24, which contains the SMA material 40, is completely immersed in the flowing fluid 18, so that the temperature is uniform throughout the actuator 24 and always equal to the temperature of the fluid 18 flowing out of the device 12.

[0028] Now referring to Fig. 5, the fluid 18 is at a temperature greater than the first temperature but less than the second temperature, so that the coil spring 42 is partially activated. Thus, the coil spring 42 partially extends longitudinally, increasing the magnitude of the first force 38 exerted on the first wall 45 of the piston 22 such that the first force 38 is greater than the second force 52 of the biasing device 26. The coil spring 42 acts on the wall 45 of the first part 44 of the piston 22 in the first longitudinal direction 76 with the first force 38, while the biasing device 26 acts on the end wall 81 of the piston 22 with the second force 52, which is less than the first force 38 of the coil spring 42.As a result of the force imbalance, the piston 22 moves in the first longitudinal direction 76 to the second position 36, where the first outlet 62 is blocked by the first part 44 and the second outlet 64 is blocked by the second part 46 of the piston 22. Thus, leakage of fluid 18 from the cavity through each outlet 62, 64 is prevented.

[0029] Now referring to Fig. 6, the fluid 18 is at a temperature at least equal to the second temperature, so that the coil spring 42 is fully activated. Thus, the coil spring 42 extends even further longitudinally to increase the magnitude of the first force 38 exerted on the first wall 45 of the piston 22 in the first longitudinal direction 76. Therefore, the first force 38 is greater than the second force 52 of the biasing device 26 and thus moves the piston 22 even further in the first longitudinal direction 76 to the third position 37. In the third position 37, the fluid 18 flows from the second portion 72 of the cavity 28, through the second outlet 64 and enters the third fluid passage 21 and the cooling device 14, which cools the fluid 18. The cooled fluid 18 then leaves the cooling device 14 and finally enters the device 12.When the piston 22 is in the third position 37, the first part 44 blocks the first outlet 62, so that fluid 18 is prevented from escaping from the cavity 28 through the first outlet 62.

[0030] Now referring to the Fig. 7 - 9, the inventive embodiment of the valve 116 according to claim 2 is shown, which is in the first position 34 ( Fig. 7), the second position 36 ( Fig. 8) and the third position 37 ( Fig. 9) can be found.

[0031] The actuator 24 is a rod assembly 142, i.e., an end-link actuator, comprising a rod 143 and a pair of wires 144 that functionally extend from opposite ends of the rod 143. Therefore, these are discrete wires 144, with one of the wires 144 being attached to one end of the rod 143 and the other wire 144 being attached to the opposite end of the rod 143. The wires 144 comprise the SMA material 40. The piston 122 is disposed in the cavity 28 and is longitudinally movable therein between the first position 34 ( Fig. 7), the second position 36 ( Fig. 8) and the third position 37 ( Fig. 9). The rod assembly 142 is operatively disposed within the cavity 28 between the first end 30 of the housing 20 and the piston 22 and is configured to act upon the piston 22.

[0032] With continued reference to the Fig. 7-9, the piston 22 includes a first portion 44, a front portion 48, and a rear portion 56. The front portion 48 and the rear portion 56 extend longitudinally from the first portion 44 in opposite directions. The first portion 44 is radially sized to fit within the cavity 28 such that fluid 18 is prevented from passing within the cavity 28 between the first portion 44 and the housing 20. The front and rear portions 48, 56 are radially sized to be smaller than the first portion 44 such that fluid 18 is permitted to flow radially around the front and rear portions 48, 56.

[0033] The piston 22 defines a recess 80 that opens from the front portion 48 and extends to an end wall 81. The rod assembly 142 is partially operatively disposed within the recess 80, and one of the wires 144 is operatively attached to the end wall 81 of the piston 22 within the recess 80, and the other of the wires 144 is operatively attached to the housing 20 at the first end 30. The rod assembly 142 is configured to act on the piston 22 and the housing 20 and exert the first force 38 in a first longitudinal direction 76, i.e., pull the piston 22 toward the first end 30 when the SMA material 40 is activated, e.g., partially or fully.

[0034] The biasing device 26 is operatively disposed within the recess 80 between the first end 30 and the piston 22. The biasing device 26 may be a compression spring 50 and surrounds the rod assembly 142 such that the biasing device is operatively disposed for reaction between the end wall 81 of the piston 22 and the first end 30 of the housing 20. The biasing device 26 is configured to act on the piston 22 in the second longitudinal direction 78, which is opposite the first longitudinal direction 76.

[0035] With continued reference to the Fig. 7-9, the piston 22 divides the cavity 28 into a first portion 70 and a second portion 72. The first portion 70 is defined between the first part 44, the front portion 48, and the housing 20. The second portion 72 is defined between the first part 44, the rear portion 56, and the housing 20 opposite the first portion 70. The first part 77 of the piston 22 defines a plurality of vent holes 60 open between the first portion 70 and the second portion 72 of the cavity 28 to provide fluid communication within the cavity 28 between the first portion 70 and the second portion 72. Therefore, fluid 18 in the first portion 70 of the cavity 28 flows through the vent holes 60 into the second portion 72 of the cavity 28.

[0036] The first inlet 58 provides fluid communication from the first fluid passage 17 to the first portion 70 of the cavity 28 regardless of the position of the piston 22. The piston 22 is functionally configured such that the first outlet 62 provides fluid communication from the first portion 70 of the cavity 28 to the second fluid passage 19 and subsequently to the heater 15 when the piston 22 is in the first position 34 ( Fig. 7). The piston 22 is also functionally configured such that the second outlet 64 provides fluid communication from the second portion 72 of the cavity 28 to the third fluid passage 21 when the piston 22 is in the third position 37 ( Fig. 9). However, when the piston 22 is in the second position 36, as in Fig. 8, the first part 44 of the piston 22 blocks the first outlet 62 and the second outlet 64. Thus, leakage of fluid 18 from the valve 116 through these outlets 62, 64 is prevented when the piston 22 is in the second position 36.

[0037] Specifically referring to Fig. 7, when the valve 116 is in the first position 34, the fluid 18 is at a temperature no greater than the first temperature, and the rod assembly 142 is deactivated, so that the pair of wires 144 are longitudinally extended. Thus, the extended wires 144 do not act between the piston 22 and the first end 30 of the housing 20 in the first longitudinal direction 76, so that the rod assembly 142 does not exert a first force 38 in the first longitudinal direction 76, while the biasing device 20 reacts between the first end 30 and the piston 22 in the second longitudinal direction 78 opposite the first longitudinal direction 76 with a second force 52 to maintain the piston 22 in the first position 34. In the first position 34, the fluid 18 flows into the first section 70 of the cavity 28, so that the SMA material 40 of the actuator wires 144 is continuously immersed in the fluid 18.The first part 44 blocks the second outlet 64, while the fluid 18 then exits the first portion 70 of the first cavity 28 through the first outlet 62 and into the second fluid passage 19. The fluid 18 then enters the heater 15 before flowing back into the device 12.

[0038] Now referring to Fig. 8, the fluid 18 is at a temperature greater than the first temperature but less than the second temperature, so that the rod assembly 142 is partially activated. Thus, the wires 144 contract longitudinally, increasing a magnitude of the first force 38 exerted on the piston 22 in the first longitudinal direction 76, such that the first force 38 is greater than the second force 52 of the biasing device 26.When partially activated, the pair of wires 144 of the rod assembly 142 act in tension between the end wall 81 of the piston 22 and the first end 30 of the housing 20 to pull the piston 22 in the first longitudinal direction 76 with the first force 38, while the biasing device 26 also acts in the second direction 78 between the piston 22 and the first end 30 of the housing 20 with the second force 52, which is less than and opposite to the first force 38 exerted by the rod assembly 142 in the first longitudinal direction 76. The force imbalance causes movement of the piston 22 in the first longitudinal direction 76 until the piston 22 reaches the second position 36 to block the first and second outlets 62.

[0039] With continued reference to Fig. 8, in the second position 36, the fluid 18 flows into the first section 70 of the cavity 28, so that the SMA material 40 of the actuator wires 144 is continuously immersed in the fluid 18. The first part 44 blocks the first and second outlets 62, 64, preventing the fluid 18 from escaping from the cavity 28 through the outlet 62, 64. Thus, unnecessary circulation of the fluid 18 is prevented.

[0040] Referring to Fig. 9, the fluid 18 is at a temperature at least equal to the second temperature, so that the pair of wires 144 of the rod assembly 142 are fully activated to act in tension and pull the piston 22 further toward the first end 30. Thus, the wires 144 of the rod assembly 142 contract even further longitudinally to increase the magnitude of the first force 38 exerted on the piston 22 in the first longitudinal direction 76. The use of the two wires 144 also provides dual displacement due to the SMA materials 40 used in each separate wire 144.

[0041] With continued reference to Fig. 9, in the third position 37, the fluid 18 flows into the first portion 70 of the cavity 28, so that the SMA material 40 of the actuator wires 144 is continuously immersed in the fluid 18. The first part 44 blocks the first outlet 62 while the fluid 18 flows from the first portion 70 of the cavity 28 through the vent holes 60 and enters the second portion 72 of the cavity 28. The fluid 18 then leaves the second portion 72 of the cavity 28 through the second outlet 64 and enters the third fluid passage 21. The fluid 18 then enters the cooling device 14 for cooling to a lower temperature before flowing back into the device 12.

[0042] Now, with reference to the Fig. 10 - 12 shown embodiment of the invention according to claim 3, the valve 216 in the first position 34 ( Fig. 10), the second position 36 ( Fig. 11) and the third position 37 ( Fig. 12).

[0043] The actuator 24 is a coil spring 42 comprising the SMA material 40. A piston 22 is arranged in the cavity 28 and is longitudinally movable therein between the first position 34 ( Fig. 7), the second position 36 ( Fig. 8) and the third position 37 ( Fig. 9) is movable longitudinally therein. The actuator 24 of the coil spring 42 is operatively disposed within the cavity 28 between the second end 32 of the housing 20 and the piston 22 and is configured to act on the piston 22 in the first longitudinal direction 76.

[0044] With continued reference to the Fig. 10-12, the piston 22 includes a first portion 44, a front portion 48, and a rear portion 56. The front portion 48 and the rear portions 56 extend longitudinally from the first portion 44 in opposite directions to each other. The front portion 48 is longitudinally disposed between the first portion 44 and the first end 30 of the housing 20. Likewise, the rear portion 56 extends longitudinally from a first wall 45 of the first portion 44 such that the rear portion 56 is longitudinally disposed between the first portion 44 and the second end 32 of the housing 20. The first portion 44 is radially sized to fit within the cavity 28 such that passage of the fluid 18 in the cavity 28 between the first portion 44 and the housing 20 is prevented.The front and rear portions 48, 56 are radially sized to be smaller than the first portion 44 such that flow of fluid 18 radially around the front and rear portions 48, 56 between the first portion 44, the housing 20, and the respective front and rear portions 48, 56 is permitted. The actuator 24 of the coil spring 42 is operatively disposed within the cavity 28 to react between the second end 32 of the housing 20 and the first portion 44 of the piston 22. The coil spring 42 is wrapped around the rear portion 56 such that the coil spring 42 acts on the first wall 45. When activated (i.e., partially or fully), the coil spring 42 is configured to exert a first force 38 on the piston 22 in the first longitudinal direction 76.

[0045] The piston 22 defines a recess 80 that opens from the front portion 48 and extends longitudinally therein to an end wall 81. The biasing device 26 may be operatively disposed within the recess 80 so as to react between the end wall 81 of the piston 22 and the first end 30 of the housing 20. The biasing device 26 may be a compression spring 50. The biasing device 26 is configured to act on the piston 22 with the second force 52 in the second longitudinal direction 78 opposite the first force 38 acting in the first longitudinal direction 76.

[0046] With continued reference to the Fig. 10-12, the piston 22 divides the cavity 28 into a first portion 70 and a second portion 72. In this embodiment, the first portion 70 is defined between the first part 44, the rear portion 56, and the housing 20 at the second end 32. The second portion 72 of the cavity 28 is defined between the first part 44, the front portion 48, and the housing 20 at the first end 30 opposite the first portion 70. The first part 44 of the piston 22 defines a plurality of vent holes 60 open between the first portion 70 and the second portion 72 to provide fluid communication between the first portion 70 and the second portion 72 of the cavity 28. Therefore, fluid 18 enters the first portion 70 of the cavity 28 and flows through the vent holes 60 into the second portion 72 of the cavity 28.

[0047] The piston 22 is functionally configured such that the first inlet 58 provides fluid communication from the first fluid passage 17 to the first portion 70 of the cavity 28 regardless of the position of the piston 22. The first outlet 62 provides fluid communication from the second portion 72 of the cavity 28 to the second fluid passage 19 and the heater 15 when the piston 22 is in the first position 34 ( Fig. 10). The second outlet 64 provides fluid communication from the first portion 70 of the cavity 28 to the third fluid passage 21 when the piston 22 is in the third position 37 ( Fig. 12). However, when the piston 22 is in the second position 36, as in Fig. 11, the first part 44 of the piston 22 blocks the first outlet 62 and the second outlet 64. Thus, leakage of fluid 18 from the valve 216 may be restricted or prevented when the piston 22 is in the second position 36.

[0048] Now referring to Fig. 10, the fluid 18 is at a temperature no greater than the first temperature, and the coil spring 42 is deactivated, so that the piston 22 is held in the first position 34. In the first position 34, the fluid 18 flows through the first inlet 58 and into the first portion 70 of the cavity 28. The fluid 18 then flows through the vent holes 60 and into the second portion 72 of the cavity 28. The fluid 18 then leaves the second portion 72 of the cavity 28 through the first outlet 62 and enters the second fluid passage 19 and then into the heater 15, in which the fluid 18 is heated. The fluid 18 then flows from the heater 15 to the device 12.

[0049] Now referring to Fig. 11, the fluid 18 is at a temperature greater than the first temperature but less than the second temperature, so that the coil spring 42 is partially activated. Thus, the coil spring 42 extends longitudinally, increasing the magnitude of the first force 38, wherein the first force 38 is greater than the second force 52 of the biasing device 26. The coil spring 42 acts between the first wall 45 of the piston 22 and the second end 32 of the housing 20 in the first longitudinal direction 76 with the first force 38. At the same time, the biasing device 26 also acts between the end wall of the piston 22 and the first end 30 of the housing 20 in the second longitudinal direction 78 with the second force 52, which is less than the first force 38 and opposite to that applied by the coil spring 42. Thus, the piston 22 moves in the first longitudinal direction 76 until the forces 38, 52 are balanced, ie the second position 36.In the second position 36, the first and second outlets 62, 64 are blocked by the first part 44 of the piston 22. Thus, the piston 22 restricts or prevents the fluid 18 from exiting the cavity 28 through one of the outlets 62, 64.

[0050] Now referring to Fig. 12, the fluid 18 is at a temperature at least equal to the second temperature, so that the coil spring 42 is fully activated. Thus, the actuator 24 of the coil spring 42 extends even further longitudinally to further increase the magnitude of the first force 38 exerted between the first wall 45 of the piston 22 and the second end 32 of the housing 20. Therefore, the first force 38 is greater than the second force 52 of the biasing device 26 to move the piston 22 even further in the first longitudinal direction 76 until the third position 37 is reached. In the third position 37, the first part blocks the first outlet 62, and the fluid 18 flows from the first portion 70 of the cavity 28 through the second outlet 64 and enters the third fluid passage 18. The fluid 18 enters the cooling device 14, which cools the fluid 18. The cooled fluid 21 leaves the cooling device 14 and returns to the device 12.

[0051] Now referring to the Fig. 13 - 15, the valve 316 is shown. The piston 22 is arranged in the cavity 28 and is longitudinally movable therein between the first position 34 ( Fig. 13), the second position 36 ( Fig. 14) and the third position 37 ( Fig. 15) movable in the longitudinal direction.

[0052] The actuator 24 is a coil spring 42 comprising the SMA material 40. The actuator 24 of the coil spring 42 is operatively disposed within the cavity 28 between the second end 32 of the housing 20 and the piston 22 and configured to act on the piston 22 in the first longitudinal direction 76. The piston 22 includes a first portion 44, a second portion 46, and a front portion 48. The first portion 44 is longitudinally spaced from the second portion 46 such that the front portion 48 is longitudinally disposed between the first portion 44 and the second portion 46. The front part 48 serves as an intermediate part for connecting the first part 44 and the second part 46. The first part 44 and the second part 46 are radially dimensioned to fit into the cavity 28, thus preventing the fluid 18 from entering the cavity 28 between the first part 44 or the second part 46 and the housing 20.The front part 48 is radially dimensioned to be smaller than the first part 44 and the second part 46 so that a flow of the fluid 18 is permitted radially around the front part 48, between the front part 48, the first part 44, the second part 46 and the housing 20.

[0053] The piston 22 may define a first recess 80 opening from the second portion 46 and extending into the front portion 48, terminating at an end wall 81. The first portion 44 defines a second recess 90 extending longitudinally to a base wall 95. The piston defines an aperture 92 extending between the end wall 81 and the base wall 95. Thus, the aperture 92 provides fluid communication between the first recess 80 and the second recess 90.

[0054] The coil spring 42 is operatively disposed in the cavity 28 between the first part 44 opposite the front part 48 and the housing 20. The coil spring 42 is configured to act on the first part 44 and exert the first force 38 in the first longitudinal direction 76.

[0055] The preloading device 26 is operatively disposed within the cavity 28 and configured to act on the piston 22 with the second force 52 in the second longitudinal direction 78, opposite the first force 38 acting in the first longitudinal direction 76. More specifically, the preloading device 26 is partially operatively disposed within the first recess 80 to react between the end wall 81 of the piston 22 and the first end 30 of the housing 20 to exert a second force 52 on the piston 22 in the second longitudinal direction 78, opposite the first longitudinal direction 76.

[0056] The actuator 24 of the coil spring 42 may similarly be disposed in the second recess 90 to react between the base wall 95 of the piston 22 and the second end 32 of the housing 20 to exert the first force 38 in the first longitudinal direction 76. Resetting a portion of the biasing device 26 in the first recess 80 and a portion of the coil spring 42 in the second recess 90 provides a valve 316 that has a compact size without sacrificing a desired travel of the piston 22 within the cavity 28.

[0057] The piston 22 is operatively disposed within the cavity to divide the cavity into a first portion 70 and a second portion 72. The first portion 70 of the cavity 28 is defined between the first portion 44, the second portion 46, the front portion 48, and the housing 20. The front portion 48 of the piston 22 defines a plurality of vent holes 60 that are open to provide fluid communication between the first portion 70 and the first recess 80. Therefore, fluid 18 enters the first portion 70 of the cavity 28 and flows through the vent holes 60 and into the first recess 80. The fluid 18 then flows from the first recess 80 through the aperture 92 into the second recess 90 and into the second portion 72 of the cavity 28, as shown in FIGS. Fig. 13-15. This allows the actuator 24, which contains the SMA material 40, to be completely immersed in the flowing fluid 18, so that the temperature is evenly distributed throughout the actuator 24 and always equal to the temperature of the fluid 18. Thus, the SMA material 40 of the actuator 24 of the coil spring 42 remains in continuous fluid communication with the fluid 18 received by the device 12.

[0058] The piston 22 is functionally configured such that the first inlet 58 provides fluid communication from the first fluid passage 17 to the first portion 70 of the cavity 28 regardless of the position of the piston 22. With reference to Fig. 13, when the piston 22 is in the first position 34, the second part 46 of the piston 22 blocks the second outlet 64, and fluid 18 flows from the first portion 70 of the cavity 28 through the first outlet 62 and into the second fluid passage 19. With reference to Fig. 15 blocks, when the piston 22 is in the third position 37, the first part 44 of the piston 22, the first outlet 62 and fluid 18 flows from the first portion 70 of the cavity 28 through the second outlet 64 and into the third fluid passage 21. However, when the piston 22 is in the second position 36, as in Fig. 14, the first portion 44 of the piston 22 blocks the first outlet 62 and the second portion 46 of the piston 22 blocks the second outlet 64. Thus, leakage of fluid 18 from the valve 316 is restricted or prevented when the piston 22 is in the second position 36.

[0059] Now referring to Fig. 13, the fluid 18 is at a temperature no greater than the first temperature, and the actuator 24 of the coil spring 42 is deactivated, so that the coil spring 42 is contracted in the longitudinal direction. The contracted coil spring 42 acts on the end wall 81 in the first part 44 of the piston 22 in the first longitudinal direction 76 with a first force 38, while the preloading device 26 acts on the end wall 81 in the front part 48 in the second longitudinal direction 78 opposite the first longitudinal direction 76 with a second force 52 that is no less than the first force 38 of the coil spring 42. Thus, the piston 22 is held in the first position 34.

[0060] Referring again to Fig. 14, the fluid 18 is at a temperature greater than the first temperature but less than the second temperature, so that the coil spring 42 is partially activated. Thus, the coil spring 42 extends longitudinally, increasing the magnitude of the first force 38 such that the first force 38 is greater than the second force 52 of the biasing device 26. The coil spring 26 acts on the base wall 95 of the first portion 44 of the piston 22 in the first longitudinal direction 76 with the first force 38, while the biasing device 26 acts on the base wall 95 of the second portion 46 with the second force 52, which is less than the first force 38 of the coil spring 42, to move the piston 22 in the first longitudinal direction 76 until the first and second forces 38, 52 are offset from each other to maintain the piston 22 in the second position 36. In the second position 36, the first and second outlets 62, 64 are blocked by the piston 22.Thus, the fluid 18 is restricted or prevented from escaping from the cavity 28 through outlet 62, 64.

[0061] Now referring again to Fig. 15, the fluid 18 is at a temperature at least equal to the second temperature, so that the coil spring 42 is fully activated. Thus, the coil spring 42 extends even further in the longitudinal direction to further increase the magnitude of the first force 38. Therefore, the first force 38 is again greater than the second force 52 of the biasing device 26 and moves the piston 22 even further in the first longitudinal direction 76 to the third position 37. In the third position 37, the fluid 18 flows from the first portion 70 of the cavity 28 through the second outlet 64 and enters the third fluid passage 21 and the cooling device 14. The fluid 18 leaves the cooling device 14 and ultimately enters the device 12.

[0062] Additionally, with reference to the Fig. 13 - 15, the coil spring type 42 of the actuator 24 can be replaced with the tube assembly type 142 of the actuator 24, which has two or more SMA wires connected together to increase the stroke for a given total length, as described with reference to the embodiment shown in the Fig. 7 - 9 shown embodiment is described.

[0063] It should also be noted that with respect to the second position 36, each of the valves 16, 116, 216, 316 may be configured so as not to block complete exit of the fluid 18 from the cavity 27 through the first and / or second outlets 62, 64. Instead, in the second position, the piston 22 may be positioned to allow a reduced amount of fluid 18 to exit through the first and / or second outlets 62, 64.

[0064] In yet another alternative, in the second position 36, the housing 20 of the valve 16, 116, 216, 316 may define an additional outlet that bypasses the heating device 15 and the cooling device 14 and returns the fluid 18 directly to the devices 12.

Claims

[1] A valve (16) configured to direct the fluid flow (18) received by a device (12) to one of a heating device (15) and a cooling device (14) in a fluid circuit as a function of a temperature of the fluid, the valve (16) comprising: a housing (20) defining a cavity (28) extending longitudinally between a first end and a second end, the cavity (28) being configured to receive and discharge the fluid; a piston (22) disposed within the cavity (28) and movable longitudinally therein between a first position (34), a second position (36), and a third position (37), the piston (22) comprising a first part (44), a second part (46), a front part (48), and a rear part (56), the first part (44) being longitudinally spaced from the second part (46); the front part (48) serving as an intermediate part for connecting the first part (44) to the second part (46); the first part (44) and the second part (46) being radially dimensioned to fit within the cavity (28) such that the fluid (18) is prevented from passing within the cavity (28) between the first part (44) or the second part (46) and the housing (20);the front part (48) is radially dimensioned to be smaller than the first part (44) and the second part (46) such that fluid flow (18) is permitted radially around the front part (48), between the front part (48), the first part (44), the second part (46), and the housing (20); the rear part (56) extends from the first part (46) opposite the front part (48) such that the first part (46) is longitudinally disposed therebetween; and the rear part (56) is radially dimensioned to be smaller than the first part (44); wherein the piston (22) defines a recess (80) opening from the second part (46) and extending through the part (46), the front part (48), the first part (44), and into the rear part (56), where the recess (80) terminates at an end wall (81); an actuator (24) operatively disposed within the cavity (28) and configured for continuous fluid communication with the fluid received by the device (12); wherein the actuator (24) is a coil spring comprising shape memory alloy material configured to be deactivated in response to the temperature of the fluid not being greater than a first temperature, such that the shape memory alloy material deactivates the actuator (24); wherein the shape memory alloy material is configured to be fully activated in response to the temperature of the fluid being at least equal to a second temperature, such that full activation of the shape memory alloy material causes full activation of the actuator (24); wherein the shape memory alloy material is configured to be partially activated in response to the temperature of the fluid being greater than the first temperature and less than the second temperature, such that the shape memory alloy material causes partial activation of the actuator (24); wherein the actuator (24) is configured to continuously act on the piston (22) when the actuator (24) is partially activated so that the piston (22) moves to the second position (36); wherein the actuator (24) is configured to continuously act on the piston (22) when the actuator (24) is fully activated so that the piston (22) moves to the third position (37); wherein flow of fluid from the cavity (28) to the heater (15) and from the heater (15) to the device (12) is permitted when the piston (22) is in the first position (34); wherein a flow of fluid from the heating device (15) and the cooling device (14) is prevented when the piston (22) is in the second position (36); and wherein a flow of fluid from the cavity (28) to the cooling device (14) and from the cooling device (14) to the device (12) is permitted when the piston (22) is in the third position (37). [2] A valve (116) configured to direct the fluid flow (18) received by a device (12) to one of a heating device (15) and a cooling device (14) in a fluid circuit as a function of a temperature of the fluid, the valve (116) comprising: a housing (20) defining a cavity (28) extending longitudinally between a first end and a second end, the cavity (28) being configured to receive and discharge the fluid; a piston (22) disposed within the cavity (28) and movable longitudinally therein between a first position (34), a second position (36), and a third position (37), the piston (22) having a first part (44), a front part (48), and a rear part (56); the front part (48) and the rear part (56) extending longitudinally from the first part (44) in opposite directions to each other; the first part (44) being radially dimensioned to fit within the cavity (28) such that the fluid (18) is prevented from passing within the cavity (28) between the first part (44) and the housing (20); and the front and rear parts (48, 56) are radially dimensioned to be smaller than the first part (44) so ​​as to permit flow of the fluid (18) radially around the front and rear parts (48, 56); wherein the piston (22) defines a recess (80) opening from the front part (48) and extending to an end wall (81); an actuator (24) operatively disposed within the cavity (28) and configured for continuous fluid communication with the fluid received by the device (12); wherein the actuator (24) is a rod assembly (142), the rod assembly (142) comprising a rod (143) and a pair of wires (144) operatively extending from opposite ends of the rod (143), the wires being made of shape memory alloy material configured to be deactivated in response to the temperature of the fluid not being greater than a first temperature, such that the shape memory alloy material deactivates the actuator (24); wherein the shape memory alloy material is configured to be fully activated in response to the temperature of the fluid being at least equal to a second temperature, such that full activation of the shape memory alloy material causes full activation of the actuator (24); wherein the shape memory alloy material is configured to be partially activated in response to the temperature of the fluid being greater than the first temperature and less than the second temperature, such that the shape memory alloy material causes partial activation of the actuator (24); wherein the actuator (24) is configured to continuously act on the piston (22) when the actuator (24) is partially activated so that the piston (22) moves to the second position (36); wherein the actuator (24) is configured to continuously act on the piston (22) when the actuator (24) is fully activated so that the piston (22) moves to the third position (37); wherein flow of fluid from the cavity (28) to the heater (15) and from the heater (15) to the device (12) is permitted when the piston (22) is in the first position (34); wherein a flow of fluid from the heating device (15) and the cooling device (14) is prevented when the piston (22) is in the second position (36); and wherein a flow of fluid from the cavity (28) to the cooling device (14) and from the cooling device (14) to the device (12) is permitted when the piston (22) is in the third position (37). [3] A valve (216) configured to direct the fluid flow (18) received by a device (12) to one of a heating device (15) and a cooling device (14) in a fluid circuit as a function of a temperature of the fluid, the valve (216) comprising: a housing (20) defining a cavity (28) extending longitudinally between a first end and a second end, the cavity (28) being configured to receive and discharge the fluid; a piston (22) disposed in the cavity (28) and movable longitudinally therein between a first position (34), a second position (36), and a third position (37), the piston (22) having a first part (44), a front part (48), and a rear part (56); the front part (48) and the rear parts (56) extend longitudinally from the first part (44) in opposite directions to each other; the front part (48) is disposed longitudinally between the first part (44) and the first end (30) of the housing (20); the rear part (56) extends longitudinally from a first wall (45) of the first part (44), such that the rear part (56) is disposed longitudinally between the first part (44) and the second end (32) of the housing (20);the first part (44) is radially dimensioned to fit within the cavity (28) so as to prevent passage of the fluid (18) in the cavity (28) between the first part (44) and the housing (20); and the front and rear parts (48, 56) are radially dimensioned to be smaller than the first part (44) so ​​as to permit flow of the fluid (18) radially around the front and rear parts (48, 56) between the first part (44), the housing (20) and the respective front and rear parts (48, 56); wherein the piston (22) defines a recess (80) opening from the front part (48) and extending longitudinally therein to an end wall (81); an actuator (24) operatively disposed within the cavity (28) and configured for continuous fluid communication with the fluid received by the device (12); wherein the actuator (24) is a coil spring (42) acting between the second end (32) of the housing (20) and the first part (44) of the piston 22 and comprises shape memory alloy material configured to be deactivated in response to the temperature of the fluid not being greater than a first temperature, such that the shape memory alloy material deactivates the actuator (24); wherein the shape memory alloy material is configured to be fully activated in response to the temperature of the fluid being at least equal to a second temperature, such that full activation of the shape memory alloy material causes full activation of the actuator (24); wherein the shape memory alloy material is configured to be partially activated in response to the temperature of the fluid being greater than the first temperature and less than the second temperature, such that the shape memory alloy material causes partial activation of the actuator (24); wherein the actuator (24) is configured to continuously act on the piston (22) when the actuator (24) is partially activated so that the piston (22) moves to the second position (36); wherein the actuator (24) is configured to continuously act on the piston (22) when the actuator (24) is fully activated so that the piston (22) moves to the third position (37); wherein flow of fluid from the cavity (28) to the heater (15) and from the heater (15) to the device (12) is permitted when the piston (22) is in the first position (34); wherein a flow of fluid from the heating device (15) and the cooling device (14) is prevented when the piston (22) is in the second position (36); and wherein a flow of fluid from the cavity (28) to the cooling device (14) and from the cooling device (14) to the device (12) is permitted when the piston (22) is in the third position (37). [4] A valve (316) configured to direct the fluid flow (18) received by a device (12) to one of a heating device (15) and a cooling device (14) in a fluid circuit as a function of a temperature of the fluid, the valve (316) comprising: a housing (20) defining a cavity (28) extending longitudinally between a first end and a second end, the cavity (28) being configured to receive and discharge the fluid; a piston (22) disposed in the cavity (28) and movable longitudinally therein between a first position (34), a second position (36), and a third position (37), the piston (22) comprising a first part (44), a second part (46), and a front part (48); the first part (44) being longitudinally spaced from the second part (46) such that the front part (48) is disposed longitudinally between the first part (44) and the second part (46); the front part (48) serving as an intermediate part for connecting the first part (44) and the second part (46); the first part (44) and the second part (46) are radially dimensioned to fit into the cavity (28) so as to prevent the fluid (18) from entering the cavity (28) between the first part (44) or the second part (46) and the housing (20);and the front part (48) is radially dimensioned to be smaller than the first part (44) and the second part (46) so as to permit flow of the fluid (18) radially around the front part (48), between the front part (48), the first part (44), the second part (46) and the housing (20); wherein the piston (22) defines a first recess (80) opening from the second part (46) and extending into the front part (48) and terminating at an end wall (81); an actuator (24) operatively disposed within the cavity (28) and configured for continuous fluid communication with the fluid received by the device (12); wherein the actuator (24) is a coil spring (42) comprising shape memory alloy material configured to be deactivated in response to the temperature of the fluid not being greater than a first temperature, such that the shape memory alloy material deactivates the actuator (24); wherein the shape memory alloy material is configured to be fully activated in response to the temperature of the fluid being at least equal to a second temperature, such that full activation of the shape memory alloy material causes full activation of the actuator (24); wherein the shape memory alloy material is configured to be partially activated in response to the temperature of the fluid being greater than the first temperature and less than the second temperature, such that the shape memory alloy material causes partial activation of the actuator (24); wherein the actuator (24) is configured to continuously act on the piston (22) when the actuator (24) is partially activated so that the piston (22) moves to the second position (36); wherein the actuator (24) is configured to continuously act on the piston (22) when the actuator (24) is fully activated so that the piston (22) moves to the third position (37); wherein flow of fluid from the cavity (28) to the heater (15) and from the heater (15) to the device (12) is permitted when the piston (22) is in the first position (34); wherein a flow of fluid from the heating device (15) and the cooling device (14) is prevented when the piston (22) is in the second position (36); and wherein a flow of fluid from the cavity (28) to the cooling device (14) and from the cooling device (14) to the device (12) is permitted when the piston (22) is in the third position (37).

Images