Thermal bypass valve with dynamic indication and override features

Abstract

An example valve includes: a plurality of ports comprising: an inlet port, a reservoir port configured to be fluidly coupled to a fluid reservoir, and a heat exchanger port configured to be fluidly coupled to a heat exchanger; a spool that is axially movable; a tube that is coupled to the spool and axially movable therewith; a thermal actuator that is exposed to fluid received at the inlet port, wherein the thermal actuator applies a biasing force on the tube, and wherein the biasing force varies based on a temperature of fluid; and an indicator pin that is magnetically coupled to the tube such that as the tube moves, the indicator pin moves therewith.

Description

Thermal Bypass Valve with Dynamic Indication and Override FeaturesCROSS REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority to U.S. Provisional Patent Application No. 63 / 655,265, filed on June 3, 2024, the entire contents of which are herein incorporated by reference as if fully set forth in this description.BACKGROUND

[0002] Some hydraulic applications involve using a thermal bypass valve that regulates temperature of fluid. When temperature of fluid is below a particular temperature, fluid is provided to a fluid reservoir. When temperature of fluid exceeds a particular temperature, the valve diverts fluid to a heat exchanger to cool the fluid before returning it to the fluid reservoir.

[0003] Existing thermal bypass valves involve using a eutectic system where a wax element that is temperature-sensitive is used to actuate the valve based on temperature variation. The wax element expands or retracts based on the temperature, thereby moving an elastomeric diaphragm to actuate the valve. In some applications, a specific type of hydraulic fluid is used (e.g., a phosphate ester based oil), which in turn requires the diaphragm to be made of a particular type of elastomeric compound (e.g., ethylene propylene rubber). Such elastomeric compound, however, deteriorates and its performance varies over time as the diaphragm expands and contracts with fluid temperature variations. Further, the diaphragm may wear and fail over time.

[0004] In some examples, the bypass valve may include an indicator that moves as the valve is actuated to indicate a state of the valve. The indicator may include a movable element that moves with an actuatable element of the valve, for example. As the indicator moves, a dynamic seal is typically used to seal the fluid chamber of the valve from an external environment of the valve.Such seal moves and rubs against internal surfaces of the valve as the indicator moves. As such, over time, the seal may wear, causing leakage and failure of the valve.

[0005] It may thus be desirable to configure a bypass valve to thermo-mechanically regulate the fluid temperature without relying on a eutectic system involving the wax element and diaphragm as conventional valves. It may also be desirable to configure the valve to provide a visual indication of the state of the valve without using a dynamic seal that has a high likelihood of failure. It is with respect to these and other considerations that the disclosure made herein is presented.SUMMARY

[0006] The present disclosure describes implementations that relate to a thermal bypass valve with dynamic indication and override features.

[0007] In a first example implementation, the present disclosure describes a valve. The valve includes: a plurality of ports comprising: an inlet port, a reservoir port configured to be fluidly coupled to a fluid reservoir, and a heat exchanger port configured to be fluidly coupled to a heat exchanger; a spool that is axially movable; a tube that is coupled to the spool and axially movable therewith; a thermal actuator that is exposed to fluid received at the inlet port, wherein the thermal actuator applies a biasing force on the tube, and wherein the biasing force varies based on a temperature of fluid; and an indicator pin that is magnetically coupled to the tube such that as the tube moves, the indicator pin moves therewith. When the temperature of fluid is below a first threshold temperature, the spool blocks the heat exchanger port and allows fluid received at the inlet port to flow to the reservoir port. When the temperature of fluid exceeds a second threshold temperature, the thermal actuator causes the tube and the spool to move, thereby causing the spool to block the reservoir port and allow fluid received at the inlet port to flow to the heat exchanger port, and wherein the indicator pin moves with the tube magnetically coupled thereto to provide a visual indication of whether fluid is provided through the heat exchanger port.

[0008] In a second example implementation, the present disclosure describes a system including and the valve of the first example implementation.

[0009] In a third example implementation, the present disclosure describes a method of operating the valve of the first example implementation or the system of the second example implementation.

[0010] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, implementations, and features described above, furtheraspects, implementations, and features will become apparent by reference to the figures and the following detailed description.BRIEF DESCRIPTION OF THE FIGURES

[0011] The novel features believed characteristic of the illustrative examples are set forth in the appended claims. The illustrative examples, however, as well as a preferred mode of use, further objectives and descriptions thereof, will best be understood by reference to the following detailed description of an illustrative example of the present disclosure when read in conjunction with the accompanying Figures.

[0012] Figure 1 illustrates a schematic of a system for cooling fluid, according to an example implementation.

[0013] Figure 2 illustrates a cross-sectional side view of a valve in a first state, according to an example implementation.

[0014] Figure 3 A illustrates a perspective view of a spool of the valve of Figure 2, according to an example implementation.

[0015] Figure 3B illustrates a side view of the spool of Figure 3A, according to an example implementation.

[0016] Figure 4A illustrates a perspective view of a tube of the valve of Figure 2, according to an example implementation.

[0017] Figure 4B illustrates a side view of the tube of Figure 4A, according to an example implementation.

[0018] Figure 5 illustrates a side view of the spool of Figures 3A-3B mechanically coupled to the tube of Figures 4A-4B, according to an example implementation.

[0019] Figure 6 illustrates a partial cross-sectional view of the valve of Figure 2 depicting magnetic polarization of several magnets used in the valve, according to an example implementation.

[0020] Figure 7 illustrates a cross-sectional side view of the valve of Figure 2 in a second state, according to an example implementation.

[0021] Figure 8 is a flowchart of a method for operating a valve of Figure 2 in the system of Figure1, according to an example implementation.DETAILED DESCRIPTION

[0022] Disclosed herein are systems, valves, and methods for regulating fluid temperature in a hydraulic system. A disclosed valve is configured to thermo-mechanically regulate the fluid temperature of fluid of the hydraulic system.

[0023] In an example implementation, fluid from the case of a hydraulic pump (the case drain fluid) is routed to the inlet of the valve. If temperature of the case drain fluid exceeds a threshold temperature, the valve diverts fluid flow to a heat exchanger to cool the fluid. Once the temperature of the case drain fluid is reduced, the valve allows case fluid flow directly to a fluid reservoir, bypassing the heat exchanger.

[0024] The disclosed valve relies on a thermal actuator for changing its state based on the temperature of the fluid. The thermal actuator involves an “all metal” configuration where metallic components interact with each other to actuate the valve, without using elastomeric components. In an example implementation, the thermal actuator is configured to include a spring that is temperature sensitive such that the biasing force that the spring applies to a movable element of the valve increases as fluid temperature increases and decreases as fluid temperature decreases.

[0025] In examples, the disclosed valve includes a visual indicator that indicates the state of the valve. The visual indicator moves with the movable element of the valve such that an operator observing the valve can determine the state of the valve. In the disclosed valve, the visual indicator is magnetically coupled to the movable element of the valve and does not involve using a dynamic seal prone to failure.

[0026] In some examples, the visual indicator can also be used as a manual override feature, where an operator can manually use the visual indicator to move the movable element of the valve and“flush” the heat exchanger, e.g., during maintenance.

[0027] Figure 1 illustrates a schematic of a system 100 for cooling fluid, according to an example implementation. The system 100 includes a pump 102 (e.g., a variable displacement pump). The pump 102 is configured to draw fluid from a fluid reservoir 104, and displace or discharge fluid that could have a high pressure level to one or more fluid consuming devices 106.

[0028] The fluid reservoir 104 is a tank that stores fluid at a low pressure, e.g., atmospheric pressure level or a pressure between 0 and 70 pounds per square inch (psi). The fluid reservoir 104 is drawn at two locations in Figure 1 to reduce visual clutter in the drawing.

[0029] The fluid consuming devices 106 can be hydraulic actuators, for example. Example hydraulic actuators include cylinder actuators or hydraulic motors. The block representing the fluid consuming devices 106 is drawn at two locations in Figure 1 to reduce visual clutter in the drawing.

[0030] In an example, fluid discharged from the pump 102 can first be provided to a high pressure filter manifold 108 before flowing to the fluid consuming devices 106. The high pressure filter manifold 108 can condition fluid (e.g., clean the fluid) prior to providing the fluid to the fluid consuming devices 106.

[0031] Fluid discharged from the fluid consuming devices 106 is provided back to the fluid reservoir 104. In an example, fluid returning from the fluid consuming devices 106 can first be provided to a return pressure filter manifold 110 before flowing to the fluid reservoir 104. Thereturn pressure filter manifold 110 can condition fluid (e.g., clean the fluid) prior to providing the fluid to the fluid reservoir 104.

[0032] The pump 102 can have a case drain port 112 that is fluidly coupled to a case drain line 114. The case drain line 114 relieves any excess pressure within the case or housing of the pump 102. When the pump 102 is actuated to provide fluid to the fluid consuming devices 106, most of the fluid is provided to the fluid consuming devices 106. However, at other times when the fluid consuming devices 106 do not demand fluid, the pump 102 may be operating at a substantially zero discharge fluid condition. In such condition, the pump 102 can maintain a high pressure level at its outlet port without providing fluid flow to the fluid consuming devices 106. Rather, fluid can be provided through the case drain port 112 to the case drain line 114. In some applications, the pump 102 may spend most of its operating life in such condition.

[0033] During operation of the system 100 fluid can get hot, and may damage components of the system 100. It may thus be desirable to cool fluid of the system 100 if temperature exceeds a threshold temperature. As such, the system 100 includes a case drain manifold 116 that is configured to route fluid back to the fluid reservoir 104 via reservoir line 118 when the fluid temperature is less than a particular temperature, while routing fluid to a heat exchanger 120 via heat exchanger line 122 to cool the fluid when the fluid temperature exceeds a threshold temperature.

[0034] The heat exchanger 120 can be any device that transfers heat from one medium (the fluid of the system 100) to another medium (e g., air, water, fuel, etc ). The heat exchanger 120 can remove heat from the fluid of the system 100 via air or water, for example. In one example, the heat exchanger 120 can be submerged in a cooler fluid (e.g., fuel of a vehicle) to remove heat from the fluid of the system 100 and transfer the heat to the fuel.

[0035] In examples, heat is transferred by conduction through materials that separate the mediums. For example, a shell and tube heat exchanger passes fluid from the system 100 through tubes, where an air or other cooling fluid passes over the tubes to cool the fluid.

[0036] In examples, the case drain manifold 116 can include a check valve 124 and a fdter 126. The check valve 124 prevents back flow to the case drain port 112 and the filter 126 cleans fluid prior to providing fluid back to the fluid reservoir 104 or the heat exchanger 120.

[0037] The case drain manifold 116 includes a valve 128 configured to selectively route fluid to the fluid reservoir 104 or to the heat exchanger 120 based on the temperature of fluid. As such, the valve 128 can be referred to as a bypass valve where fluid is route to the fluid reservoir 104 as long as fluid temperature is below a particular temperature, and as temperature exceeds a threshold temperature, the valve 128 is actuated to another state, causing fluid to bypass the fluid reservoir 104 and flow to the heat exchanger 120. Conversely, when fluid temperature is reduced as the fluid cools, the valve 128 causes fluid to bypass the heat exchanger 120 and flow to the fluid reservoir 104.

[0038] The valve 128 is represented schematically in Figure 1 as having a manual override feature 130, having a spring 132 to return the valve 128 to a particular state, and as being actuated via a thermal actuator 134. Figures 2-7 describe an example implementation of the valve 128.

[0039] Figure 2 illustrates a cross-sectional side view of a valve 200 in a first state (unactuated state), according to an example implementation. The valve 200 represents the valve 128 of the system 100, for example.

[0040] The valve 200 includes a housing 202 that defines a longitudinal cylindrical cavity therein. The housing 202 can have external threads 203 to facilitate inserting or screwing the valve 200into the case drain manifold 116, which has ports corresponding to ports of the valve 200 described below, and may thus fluidly couple the valve 200 to other components of the system 100 such as the fluid reservoir 104 and the heat exchanger 120.

[0041] The valve 200 includes an end cap 204 disposed at a proximal end of the housing 202. The end cap 204 defines an inlet port 206 that is configured to be fluidly coupled to the case drain line 114 of the system 100 to receive case drain fluid of the pump 102.

[0042] Reference to “distal” and “proximal” throughout this disclosure is not intended to imply a specific orientation of components of the valve 200 relative to any surrounding environment. Instead, these directional terms are intended to facilitate a description of the interrelationship between the several components of the valve 200 and their function.

[0043] The valve 200 also includes a port sleeve 208 that is disposed within the housing 202. The port sleeve 208 is generally cylindrical and hollow as shown. The port sleeve 208 is retained axially within the housing 202 between a shoulder 209 and the end cap 204. In examples, a biasing member (e.g., a spring) can be interposed between the end cap 204 and the port sleeve 208.

[0044] The housing 202 and the port sleeve 208 define a reservoir port 210 that is configured to be fluidly coupled to the fluid reservoir 104. For example, the port sleeve 208 can have one or more cross-holes such as cross-hole 211 that is aligned with a respective cross-hole 212 of the housing 202 to form the reservoir port 210.

[0045] The housing 202 and the port sleeve 208 also define a heat exchanger port 214 that is configured to be fluidly coupled to the heat exchanger 120. For example, the port sleeve 208 can have one or more cross-holes such as cross-hole 215 that is aligned with a respective cross-hole216 of the housing 202 to form the heat exchanger port 214. The cross-hole 215 is axially spaced from the cross-hole 211 along a length of the port sleeve 208 as shown.

[0046] The term “hole” is used generally herein to indicate a hollow place (e.g., cavity) in a solid body or surface, for example. The term “cross-hole” indicates a hole that crosses a path of, or is formed transverse relative to, another hole, cavity, or channel.

[0047] The port sleeve 208 defines a respective longitudinal cylindrical cavity therein. The valve 200 includes a spool 218 that is disposed, and is axially-movable, in the longitudinal cylindrical cavity of the port sleeve 208. Particularly, the spool 218 slides relative to an interior surface of the port sleeve 208. The term “spool” is used herein to encompass any type of movable element, such as a piston, a poppet, etc.

[0048] Figure 3 A illustrates a perspective view of the spool 218, and Figure 3B illustrates a side view of the spool 218, according to an example implementation. As shown, the spool 218 is generally cylindrical and is hollow. The spool 218 can have a plurality of balance grooves 300 and balance grooves 302 that are axially spaced from each other along a length of the spool 218, and are configured to facilitate axial movement of the spool 218 within the port sleeve 208 via fluid lubrication and reduction of friction.

[0049] The spool 218 further includes a plurality of openings (e.g., holes, windows, etc.) such as opening 304 and opening 306 disposed in a circular array about the spool 218. The openings 304, 306 are arcuate openings as shown in Figures 3A-3B.

[0050] The spool 218 further includes a plurality of cross-holes 308 formed in a circular array about a distal portion of the spool 218. The spool 218 further includes a plurality of slanted cross-holes 310 formed in a circular array about a tapered portion 312 of the spool 218 as depicted inFigure 3B.

[0051] The spool 218 also includes an flanged end portion 314. An undercut or annular groove is formed between the flanged end portion 314 and the tapered portion 312 such that a neck portion 316 (e.g., a reduced diameter section of the spool 218) is formed as shown in Figure 3B.

[0052] Referring back to Figure 2, the valve 200 includes a tube 220 disposed within the housing 202. The tube 220 can also be referred to as a movable sleeve / tube or a magnet carrier as described in more details below. The tube 220 is mechanically coupled, engaged, or linked with the spool 218 such that the tube 220 and the spool 218 can move axially together.

[0053] Figure 4A illustrates a perspective view of the tube 220, and Figure 4B illustrates a side view of the tube 220, according to an example implementation. The tube 220 is generally cylindrical and hollow as shown. The tube 220, however, might not have a consistent diameter. Rather, the tube 200 has a proximal or first portion 400 having a first outer diameter, a second enlarged portion 402 with a second outer diameter greater than the first outer diameter, and a third enlarged portion 404 with a third outer diameter greater than the first and second outer diameters. Referring to Figures 2, 4A-4B together, the inner diameters of the first portion 400 and the second enlarged portion 402 can be the same, while the inner diameter of the third enlarged portion 404 is greater.

[0054] Further, as shown in Figures 4A-4B, a step 406 is formed at the transition from the first portion 400 to the second enlarged portion 402. Similarly, a step is formed at the transition from the second enlarged portion 402 to the third enlarged portion 404, thereby forming a shoulder 408.

[0055] The first portion 400 has a slot 410 (e.g., a U-shaped slot) formed in a proximal end portion 412 of the tube 220. The tube 220 further includes a partial annular groove 414 formed distally from the proximal end portion 412. With this configuration, a receptacle 416 is formed via the partial annular groove 414, where the receptacle 416 is configured to receive the flanged end portion 314 of the spool 218. Arrow 418 indicates a direction where the spool 218 can be “dropped” such that the flanged end portion 314 of the spool 218 is received within the receptacle 416, and where the neck portion 316 of the spool 218 is accommodated by the slot 410.

[0056] Figure 5 illustrates a side view of the spool 218 mechanically coupled to the tube 220, according to an example implementation. As shown, the spool 218 is engaged or mechanically coupled with the tube 220 where the proximal end portion 412 is retained between the tapered portion 312 and the flanged end portion 314 of the spool 218.

[0057] With this configuration, the spool 218 and the tube 220 move axially together. In other words, if the tube 220 moves in the distal direction, it pulls the spool 218 in the distal direction therewith and vice versa. This coupling arrangement shown in Figure 5 is not meant to be limiting. Other engaging or linking configurations can be used to couple the spool 218 to the tube 220 such that they move axially together.

[0058] Referring back to Figure 2, the valve 200 includes a main sleeve 222 disposed at least partially in the housing 202. Particularly, the main sleeve 222 is received at a distal end of the housing 202 and protrudes distally outward therefrom. The main sleeve 222 is retained within the housing 202 and is thus fixedly disposed relative to the housing 202. As shown in Figure 2, the tube 220 is disposed around a proximal portion of the main sleeve 222 and is configured to slide about the exterior surface of the main sleeve 222 when the tube 220 moves axially.

[0059] The valve 200 further includes a biasing spring 223 that is disposed around the main sleeve222 and the spool 218. The biasing spring 223 may represent the spring 132 of the valve 128 shown in Figure 1, for example.

[0060] As depicted in Figure 2, the biasing spring 223 is interposed axially between the main sleeve 222 and the proximal end portion 412 of the tube 220. As the main sleeve 222 is fixed, the biasing spring 223 biases the tube 220 and the spool 218 engaged with the tube 220 in the proximal direction to the position shown in Figure 2. In this position, the end cap 204 operates as a mechanical stop for the spool 218 where the proximal end of the spool 218 contacts the distal end of the end cap 204 as depicted.

[0061] The main sleeve 222 defines a respective longitudinal cylindrical cavity therein. The valve 200 includes an indicator pin 224 that is disposed, and is axially-movable, in the longitudinal cylindrical cavity of the main sleeve 222. The indicator pin 224 also operates as a manual override feature as described in more details below and may correspond to the manual override feature 130 of the valve 128 shown in Figure 1, for example.

[0062] The valve 200 further includes a retention ring 226 that is radially interposed between the main sleeve 222 and the indicator pin 224. The indicator pin 224 can slide along the interior surface of the retention ring 226 such that the retention ring 226 operates as a guide for the indicator pin 224. Further, the retention ring 226 operates as a mechanical stop for the indicator pin 224 such that the indicator pin 224 is prevented from moving in the distal direction beyond a certain axial position at which a shoulder 228 of the indicator pin 224 reaches a proximal end of the retention ring 226.

[0063] The indicator pin 224 is magnetically coupled to the tube 220 such that as the tube 220 moves axially, the indicator pin 224 moves axially therewith. Particularly, the valve 200 has a magnet assembly or configuration that magnetically couples the tube 220 to the indicator pin 224.

[0064] For example, the valve 200 can include a ring magnet 230 that is disposed or accommodated within the third enlarged portion 404 of the tube 220. Particularly, the ring magnet 230 is radially interposed between the tube 220 and the main sleeve 222, surrounding the indicator pin 224. The distal end of the tube 220 can be swaged or crimped to retain the ring magnet 230 therein, for example. With this configuration, the tube 220 can be referred to as a magnet carrier as it carriers and moves the ring magnet 230 therewith.

[0065] Further, the valve 200 includes a magnet assembly 232 disposed within a cavity formed within the proximal portion of the indicator pin 224 as shown in Figure 2. The proximal end of the indicator pin 224 can be swaged or crimped to retain the magnet assembly 232 therein, for example. The magnet assembly 232 is coaxial with the ring magnet 230 as depicted.

[0066] In an example, the magnet assembly 232 includes a distal or first cylindrical magnet 234 and a proximal or second cylindrical magnet 236. The magnet assembly 232 can further include a magnet spacer 238 interposed between the first cylindrical magnet 234 and the second cylindrical magnet 236.

[0067] In an example, each of the ring magnet 230, the first cylindrical magnet 234, and the second cylindrical magnet 236 can be made of a single magnet. In another example, one or more of the ring magnet 230, the first cylindrical magnet 234, and the second cylindrical magnet 236 can be made of multiple magnets disposed in series.

[0068] This magnet configuration magnetically couples the indicator pin 224 to the tube 220 while stabilizing the positions of both components.

[0069] Figure 6 illustrates a partial cross-sectional view of the valve 200 depicting magnetic polarization of the ring magnet 230, the first cylindrical magnet 234, and the second cylindrical magnet 236, according to an example implementation. In the example implementation of Figure 6, the ring magnet 230 can have its north pole “N” facing in the distal direction while its south pole “S” facing in the proximal direction. On the other hand, the first cylindrical magnet 234 can have its north pole “N” facing in the proximal direction while its south pole “S” facing in the distal direction. Similarly, the second cylindrical magnet 236 can have its north pole “N” facing in the proximal direction while its south pole “S” facing in the distal direction.

[0070] As such, the first cylindrical magnet 234 and the second cylindrical magnet 236 have opposite poles facing each other. On the other hand, the ring magnet 230 has similar poles proximate to or aligned with respective poles of the first cylindrical magnet 234 and the second cylindrical magnet 236.

[0071] With this configuration, if the tube 220 moves in the distal direction, the north pole of the ring magnet 230 may repel the north pole of the first cylindrical magnet 234, causing it to move in the distal direction therewith. As the first cylindrical magnet 234 is repelled in the distal direction, it causes the indicator pin 224 to move therewith, thus following the movement of the tube 220.

[0072] The second cylindrical magnet 236 also moves with the indicator pin 224 in the distal direction. However, the south pole of the ring magnet 230 repels the south pole of the second cylindrical magnet 236 in the proximal direction, equally countering the magnetic force between the ring magnet 230 and the first cylindrical magnet 234, thereby stabilizing the position of the indicator pin 224 once the tube 220 reaches a particular axial position. This sequence of event isreversed when the tube 220 moves in the proximal direction. In other examples, the indicator pin224 can be magnetically coupled to the spool 218 rather that the tube 220.

[0073] Referring back to Figure 2, the valve 200 further includes a thermal actuator 240 disposed in a thermal actuator chamber 242. The thermal actuator 240 may represent the thermal actuator 134 of the valve 128 shown in Figure 1, for example.

[0074] The thermal actuator chamber 242 is an annular chamber that is formed between the interior surface of the housing 202 on one side and the main sleeve 222 and the spool 218 on the other side. The thermal actuator chamber 242 thus accommodates the tube 220, the ring magnet 230, and the thermal actuator 240.

[0075] The thermal actuator chamber 242 is configured to be filled with fluid received at the inlet port 206. Particularly, fluid received at the inlet port 206 flows through the spool 218, then through the plurality of cross-holes 308 and the plurality of slanted cross-holes 310 of the spool 218 to the thermal actuator chamber 242. This way, the thermal actuator 240 is immersed in fluid during operation of the valve 200.

[0076] The valve 200 includes a static seal 244 (e.g., an O-ring) that prevents leakage from the thermal actuator chamber 242 to an external environment (e.g., atmosphere) of the valve 200. Notably, the indicator pin 224 is disposed within the main sleeve 222 and is not exposed to fluid. Rather, the indicator pin 224 is subject to the atmosphere or external environment of the valve 200. As such, no dynamic seal is used to seal between the indicator pin 224 and the main sleeve 222 for example, as the indicator pin 224 moves. This is advantageous over conventional valves that use a dynamic seal that rubs against components as the indicator pin 224 moves, which could lead to failure of the seal and leakage over time (as well as other deleterious effects of dynamic seals, e.g., friction).

[0077] Further, the thermal actuator 240 is an all metal configuration where no elastomers or eutectic elements (e.g., wax) are used. Rather, the thermal actuator 240 involves a thermally- sensitive metallic component that changes a force applied to the tube 220 as the temperature of fluid changes.

[0078] In the example implementation of Figure 2, the thermal actuator 240 includes a thermally- sensitive spring 246. The thermally-sensitive spring 246 has a proximal end that rests against the port sleeve 208 (and is thus fixed) and a distal end that rests against the third enlarged portion 404 of the tube 220. As such, the thermally-sensitive spring 246 applies a first biasing force on the tube 220 (which is mechanically coupled to the spool 218) in the distal direction, opposing a second biasing force of the biasing spring 223, which biases the spool 218 and the tube 220 in the proximal direction.

[0079] The thermally-sensitive spring 246 is made of a material, the shear modulus of which changes with temperature of fluid. This way, the biasing force that the thermally-sensitive spring 246 applies to the tube 220 changes with fluid temperature.

[0080] For example, the shear modulus of the thermally-sensitive spring 246, and thus the biasing force it applies to the tube 220, can be proportional to the fluid temperature. As the fluid temperature increases, the shear modulus of the thermally-sensitive spring 246 and the biasing force it applies to the tube 220 increases, and vice versa. In one example, the thermally-sensitive spring 246 can be made of a nitinol wire coiled to form the thermally-sensitive spring 246, where nitinol is a nickel -titanium metal alloy that exhibits the thermal sensitivity described above.

[0081] In the state shown in Figure 2, the fluid temperature is below a first threshold temperature (e.g., 140 °F or 60 °C) such that the first biasing force of the thermally-sensitive spring 246 is low and is not sufficient to overcome the second biasing force of the biasing spring 223. In this state,as depicted in Figure 2, the spool 218 is disposed at an axial position at which the openings 304, 306 of the spool 218 partially overlap with the reservoir port 210 (e.g., overlap with the crossholes 211, 212) such that a flow area 248 is formed. However, the spool 218 blocks the heat exchanger port 214 (e g., blocks the cross-hole, 215 of the port sleeve 208). The term “block” is used throughout herein to indicate substantially preventing fluid flow except for minimal or leakage flow of drops per minute, for example.

[0082] As such, in the state depicted in Figure 2, fluid received at the inlet port 206 flows through the end cap 204 and the spool 218, then through the openings 304, 306, the flow area 248, and the cross-holes 211, 212 of the reservoir port 210 to the fluid reservoir 104 (via the reservoir line 118 as shown in Figure 1) directly, bypassing the heat exchanger 120. As mentioned above, fluid also flows through the plurality of cross-holes 308 and the plurality of slanted cross-holes 310 of the spool 218 to the thermal actuator chamber 242 in which the thermally-sensitive spring 246 is disposed.

[0083] If the temperature of fluid increases during operation of the system 100 above the first threshold temperature, a magnitude of the first biasing force that the thermally-sensitive spring 246 applies to the tube 220 increases. As the biasing force of the thermally-sensitive spring 246 increases, it may overcome (becomes greater than) the second biasing force of the biasing spring 223, causing the tube 220 and the spool 218 (which is coupled to the tube 220) to move in the distal direction. Once temperature exceeds a second threshold temperature (e.g., 176 °F or 80 °C), the spool 218 reaches a position at which the spool 218 blocks the reservoir port 210, while allowing flow to the heat exchanger port 214.

[0084] Figure 7 illustrates a cross-sectional side view of the valve 200 in a second state (actuated state), according to an example implementation. As shown in Figure 7 compared to Figure 2, thethermally-sensitive spring 246 has moved the tube 220 and the spool 218 in the distal direction, compressing the biasing spring 223. The proximal end of the spool 218 has moved off the distal end of the end cap 204, and the distal end of the spool 218 has reached and contacted the proximal end of the main sleeve 222.

[0085] In this axial position, the spool 218 blocks the cross-hole 211 of the port sleeve 208 (and thus blocks the reservoir port 210). However, the cross-hole 215 is now exposed and overlaps partially with the openings 304, 306, thereby causing a flow area 700 to form, allowing fluid flow to the heat exchanger port 214.

[0086] Particularly, in the state depicted in Figure 7, fluid received at the inlet port 206 flows through the end cap 204 and the spool 218, then through the openings 304, 306, the flow area 700, and the cross-holes 215, 216 of the heat exchanger port 214 to the heat exchanger 120 (via the heat exchanger line 122 as shown in Figure 1). Fluid is thus cooled then returned to the fluid reservoir 104.

[0087] As mentioned above, fluid also keeps communicating through the plurality of cross-holes 308 and plurality of slanted cross-holes 310 of the spool 218 to the thermal actuator chamber 242 in which the thermally-sensitive spring 246 is disposed. Thus, as temperature of fluid decreases, the shear modulus of the thermally-sensitive spring 246 decreases, thereby reducing the biasing force it applies on the tube 220. The biasing spring 223 may thus push the tube 220 and the spool 218 back in the proximal direction to the state shown in Figure 2.

[0088] The indicator pin 224 provides a visual indication of the state of the valve 200. As shown in Figure 7, the indicator pin 224 has shifted in the distal direction as the tube 220 moves in the distal direction due to the magnetic coupling therebetween as described above. The distal end or stem portion of the indicator pin 224 is now visible outside the main sleeve 222. As such, anoperator observing the valve 200 can determine the state of the valve 200 based on whether the indicator pin 224 protrudes outward in the distal direction from the main sleeve 222 or not.

[0089] If the indicator pin 224 is exposed or visible outside the main sleeve 222, then the valve 200 is in the second state shown in Figure 7, and fluid flows to the heat exchanger 120. On the other hand, if the indicator pin 224 is not exposed or visible outside the main sleeve 222, then the valve 200 is in the first state shown in Figure 2, and fluid flows to the fluid reservoir 104.

[0090] Further, the indicator pin 224 enables manual overriding to facilitate flushing the heat exchanger 120 whenever needed (e.g., during maintenance operations) regardless of the temperature of the fluid. For example, an operator can extend his hands within the main sleeve 222 to grip the indicator pin 224, and may pull the indicator pin outward in the distal direction. As the indicator pin 224 moves, it causes the tube 220 to move therewith due to the magnetic coupling between the indicator pin 224 and the tube 220. The tube 220 in turn pulls the spool 218 therewith, causing the valve 200 to operate in the second state shown in Figure 7, allowing fluid to flow through the heat exchanger 120, flushing it, and discharging fluid to the fluid reservoir 104 even if the temperature of the fluid is below the first threshold temperature (e.g., below 140 °F or 60 °C).

[0091] Figure 8 is a flowchart of a method 800 for operating the valve 200 in the system 100, according to an example implementation. The method 800 may include one or more operations, functions, or actions as illustrated by one or more of blocks 802-808. Although the blocks are illustrated in a sequential order, these blocks may also be performed in parallel, and / or in a different order than those described herein. Also, the various blocks may be combined into fewer blocks, divided into additional blocks, and / or removed based upon the desired implementation. It should be understood that for this and other processes and methods disclosed herein, flowcharts showfunctionality and operation of one possible implementation of present examples. Alternative implementations are included within the scope of the examples of the present disclosure in which functions may be executed out of order from that shown or discussed, including substantially concurrent or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art.

[0092] At block 802, the method 800 includes providing fluid from the case drain port 112 of the pump 102 to the inlet port 206 of the valve 200, wherein the valve 200 has the reservoir port 210 fluidly coupled to the fluid reservoir 104, and the heat exchanger port 214 fluidly coupled to the heat exchanger 120.

[0093] At block 804, the method 800 includes, when a temperature of fluid is below a first threshold temperature, causing the spool 218 of the valve 200 to block the heat exchanger port 214 and allow fluid received at the inlet port 206 to flow to the reservoir port 210.

[0094] At block 806, the method 800 includes, when the temperature of fluid exceeds a second threshold temperature, causing the thermal actuator 240 of the valve 200 to move the spool 218, thereby causing the spool 218 to block the reservoir port 210 and allow fluid received at the inlet port 206 to flow to the heat exchanger port 214.

[0095] At block 808, the method 800 includes causing the indicator pin 224 to move, via magnetic coupling, with the spool 218 to provide a visual indication of whether fluid is provided through the heat exchanger port 214.

[0096] The method 800 can include any further steps described throughout his disclosure.

[0097] The detailed description above describes various features and operations of the disclosed systems with reference to the accompanying figures. The illustrative implementations describedherein are not meant to be limiting. Certain aspects of the disclosed systems can be arranged and combined in a wide variety of different configurations, all of which are contemplated herein.

[0098] Further, unless context suggests otherwise, the features illustrated in each of the figures may be used in combination with one another. Thus, the figures should be generally viewed as component aspects of one or more overall implementations, with the understanding that not all illustrated features are necessary for each implementation.

[0099] Additionally, any enumeration of elements, blocks, or steps in this specification or the claims is for purposes of clarity. Thus, such enumeration should not be interpreted to require or imply that these elements, blocks, or steps adhere to a particular arrangement or are carried out in a particular order.

[0100] Further, devices or systems may be used or configured to perform functions presented in the figures. In some instances, components of the devices and / or systems may be configured to perform the functions such that the components are actually configured and structured (with hardware and / or software) to enable such performance. In other examples, components of the devices and / or systems may be arranged to be adapted to, capable of, or suited for performing the functions, such as when operated in a specific manner.

[0101] By the term “substantially” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those with skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide

[0102] The arrangements described herein are for purposes of example only. As such, those skilled in the art will appreciate that other arrangements and other elements (e.g., machines, interfaces, operations, orders, and groupings of operations, etc.) can be used instead, and some elements may be omitted altogether according to the desired results. Further, many of the elements that are described are functional entities that may be implemented as discrete or distributed components or in conjunction with other components, in any suitable combination and location.

[0103] While various aspects and implementations have been disclosed herein, other aspects and implementations will be apparent to those skilled in the art. The various aspects and implementations disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope being indicated by the following claims, along with the full scope of equivalents to which such claims are entitled. Also, the terminology used herein is for the purpose of describing particular implementations only, and is not intended to be limiting.

[0104] Embodiments of the present disclosure can thus relate to one of the enumerated example embodiments (EEEs) listed below.

[0105] EEE l is a valve comprising: a plurality of ports comprising: an inlet port, a reservoir port configured to be fluidly coupled to a fluid reservoir, and a heat exchanger port configured to be fluidly coupled to a heat exchanger; a spool that is axially movable; a tube that is coupled to the spool and axially movable therewith; a thermal actuator that is exposed to fluid received at the inlet port, wherein the thermal actuator applies a biasing force on the tube, and wherein the biasing force varies based on a temperature of fluid; and an indicator pin that is magnetically coupled to the tube such that as the tube moves, the indicator pin moves therewith, wherein when the temperature of fluid is below a first threshold temperature, the spool blocks the heat exchanger port and allows fluid received at the inlet port to flow to the reservoir port, and wherein when thetemperature of fluid exceeds a second threshold temperature, the thermal actuator causes the tube and the spool to move, thereby causing the spool to block the reservoir port and allow fluid received at the inlet port to flow to the heat exchanger port, and wherein the indicator pin moves with the tube magnetically coupled thereto to provide a visual indication of whether fluid is provided through the heat exchanger port.

[0106] EEE 2 is the valve of EEE 1, wherein the thermal actuator comprises a thermally-sensitive spring applying the biasing force on the tube, wherein a shear modulus of the thermally-sensitive spring varies based on the temperature of fluid.

[0107] EEE 3 is the valve of EEE 2, wherein the thermally-sensitive spring comprises a nitinol wire that is coiled to form the thermally-sensitive spring.

[0108] EEE 4 is the valve of any of EEEs 1-3, wherein the tube is magnetically coupled to the indicator pin via a magnet configuration comprising: a ring magnet mounted to the tube and surrounding the indicator pin; and a magnet assembly disposed within the indicator pin, coaxial with the ring magnet.

[0109] EEE 5 is the valve of EEE 4, wherein the magnet assembly comprises: a first cylindrical magnet; a second cylindrical magnet; and a magnet spacer interposed between the first cylindrical magnet and the second cylindrical magnet.

[0110] EEE 6 is the valve of EEE 5, wherein the first cylindrical magnet and the second cylindrical magnet have opposite poles facing each other, wherein the ring magnet has similar poles aligned with respective poles of the first cylindrical magnet and the second cylindrical magnet.

[0111] EEE 7 is the valve of any of EEEs 1 -6, wherein the biasing force is a first biasing force applied on the tube in a distal direction, and wherein the valve further comprises: a biasing spring applying a second biasing force on the tube in a proximal direction, wherein when the temperature of fluid is below the first threshold temperature, the second biasing force is greater than the first biasing force, and wherein when the temperature of fluid exceeds the second threshold temperature, the first biasing force is greater than the second biasing force.

[0112] EEE 8 is the valve of any of EEEs 1-7, further comprising: a housing having a longitudinal cylindrical cavity in which the spool, the tube, and the thermal actuator are disposed.

[0113] EEE 9 is the valve of EEE 8, wherein the housing has a first cross-hole and a second cross-hole, and wherein the valve further comprises: a port sleeve disposed within the housing and having (i) a respective first cross-hole aligned with the first cross-hole of the housing to form the reservoir port, and (ii) a respective second cross-hole aligned with the second cross-hole of the housing to form the heat exchanger port.

[0114] EEE 10 is the valve of EEE 9, wherein the spool has a plurality of openings disposed in a circular array about the spool, wherein when the temperature of fluid is below the first threshold temperature, the plurality of openings partially overlap with the first cross-hole and the respective first cross-hole to form a flow area allowing fluid flow through the reservoir port, and wherein when the temperature of fluid exceeds the second threshold temperature and the spool moves, the plurality of openings partially overlap with the second cross-hole and the respective second crosshole to form a respective flow area allowing fluid flow through the heat exchanger port.

[0115] EEE 11 is the valve of any of EEEs 8-10, further comprising: a main sleeve disposed partially with the housing, wherein the indicator pin is axially movable within the main sleeve, and wherein the tube is configured to slide about an exterior surface of the main sleeve.

[0116] EEE 12 is a system comprising: a pump having a drain port from which case drain fluid of the pump is discharged; a fluid reservoir; a heat exchanger; and the valve of any of EEEs 1-11. For example, the valve comprises: a plurality of ports comprising: an inlet port that is fluidly coupled to the drain port of the pump, a reservoir port configured to be fluidly coupled to the fluid reservoir, and a heat exchanger port configured to be fluidly coupled to the heat exchanger, a spool that is axially movable, a tube that is coupled to the spool and axially movable therewith, a thermal actuator that is exposed to fluid received at the inlet port, wherein the thermal actuator applies a biasing force on the tube, and wherein the biasing force varies based on a temperature of fluid, and an indicator pin that is magnetically coupled to the tube such that as the tube moves, the indicator pin moves therewith, wherein when the temperature of fluid is below a first threshold temperature, the spool blocks the heat exchanger port and allows fluid received at the inlet port to flow to the reservoir port then to the fluid reservoir, and wherein when the temperature of fluid exceeds a second threshold temperature, the thermal actuator causes the tube and the spool to move, thereby causing the spool to block the reservoir port and allow fluid received at the inlet port to flow to the heat exchanger port to the heat exchanger, and wherein the indicator pin moves with the tube magnetically coupled thereto to provide a visual indication of whether fluid is provided to the heat exchanger.

[0117] EEE 13 is the system of EEE 12, wherein the thermal actuator comprises a thermally- sensitive spring applying the biasing force on the tube, wherein a shear modulus of the thermally- sensitive spring varies based on the temperature of fluid.

[0118] EEE 14 is the system of EEE 13, wherein the thermally-sensitive spring comprises a nitinol wire that is coiled to form the thermally-sensitive spring.

[0119] EEE 15 is the system of any of EEEs 12-14, wherein the tube is magnetically coupled to the indicator pin via a magnet configuration comprising: a ring magnet mounted to the tube and surrounding the indicator pin; and a magnet assembly disposed within the indicator pin, coaxial with the ring magnet.

[0120] EEE 16 is the system of EEE 15, wherein the magnet assembly comprises: a first cylindrical magnet; a second cylindrical magnet; and a magnet spacer interposed between the first cylindrical magnet and the second cylindrical magnet.

[0121] EEE 17 is the system of EEE 16, wherein the first cylindrical magnet and the second cylindrical magnet have opposite poles facing each other, wherein the ring magnet has similar poles aligned with respective poles of the first cylindrical magnet and the second cylindrical magnet.

[0122] EEE 18 is the system of any of EEEs 12-17, wherein the biasing force is a first biasing force applied on the tube in a distal direction, and wherein the valve further comprises: a biasing spring applying a second biasing force on the tube in a proximal direction, wherein when the temperature of fluid is below the first threshold temperature, the second biasing force is greater than the first biasing force, and wherein when the temperature of fluid exceeds the second threshold temperature, the first biasing force is greater than the second biasing force.

[0123] EEE 19 is a method of operating the valve of any of EEEs 1-11 and / or the system of any of EEEs 12-18. For example, the method comprises: providing fluid from a case drain port of a pump to an inlet port of a valve, wherein the valve has a reservoir port fluidly coupled to a fluid reservoir, and a heat exchanger port fluidly coupled to a heat exchanger; when a temperature of fluid is below a first threshold temperature, causing a spool of the valve to block the heat exchanger port and allow fluid received at the inlet port to flow to the reservoir port; when the temperatureof fluid exceeds a second threshold temperature, causing a thermal actuator of the valve to move the spool, thereby causing the spool to block the reservoir port and allow fluid received at the inlet port to flow to the heat exchanger port; and causing an indicator pin to move, via magnetic coupling, with the spool to provide a visual indication of whether fluid is provided through the heat exchanger port.

[0124] EEE 20 is the method of EEE 19, wherein the thermal actuator comprises a thermally- sensitive spring, wherein causing the thermal actuator to move the spool comprises: causing the thermally-sensitive spring to apply a biasing force that moves the spool.

Claims

CLAIMSWhat is claimed is:1 . A val ve com pri si ng : a plurality of ports comprising: an inlet port, a reservoir port configured to be fluidly coupled to a fluid reservoir, and a heat exchanger port configured to be fluidly coupled to a heat exchanger; a spool that is axially movable; a tube that is coupled to the spool and axially movable therewith; a thermal actuator that is exposed to fluid received at the inlet port, wherein the thermal actuator applies a biasing force on the tube, and wherein the biasing force varies based on a temperature of fluid; and an indicator pin that is magnetically coupled to the tube such that as the tube moves, the indicator pin moves therewith, wherein when the temperature of fluid is below a first threshold temperature, the spool blocks the heat exchanger port and allows fluid received at the inlet port to flow to the reservoir port, and wherein when the temperature of fluid exceeds a second threshold temperature, the thermal actuator causes the tube and the spool to move, thereby causing the spool to block the reservoir port and allow fluid received at the inlet port to flow to the heat exchanger port, and wherein the indicator pin moves with the tube magnetically coupled thereto to provide a visual indication of whether fluid is provided through the heat exchanger port.

2. The valve of claim 1 , wherein the thermal actuator comprises a thermally-sensitive spring applying the biasing force on the tube, wherein a shear modulus of the thermally-sensitive spring varies based on the temperature of fluid.

3. The valve of claim 2, wherein the thermally-sensitive spring comprises a nitinol wire that is coiled to form the thermally-sensitive spring.

4. The valve of claim 1, wherein the tube is magnetically coupled to the indicator pin via a magnet configuration comprising: a ring magnet mounted to the tube and surrounding the indicator pin; and a magnet assembly disposed within the indicator pin, coaxial with the ring magnet.

5. The valve of claim 4, wherein the magnet assembly comprises: a first cylindrical magnet; a second cylindrical magnet; and a magnet spacer interposed between the first cylindrical magnet and the second cylindrical magnet.

6. The valve of claim 5, wherein the first cylindrical magnet and the second cylindrical magnet have opposite poles facing each other, wherein the ring magnet has similar poles aligned with respective poles of the first cylindrical magnet and the second cylindrical magnet.

7. The valve of claim 1, wherein the biasing force is a first biasing force applied on the tube in a distal direction, and wherein the valve further comprises: a biasing spring applying a second biasing force on the tube in a proximal direction, wherein when the temperature of fluid is below the first threshold temperature, the second biasing force is greater than the first biasing force, and wherein when the temperature of fluid exceeds the second threshold temperature, the first biasing force is greater than the second biasing force.

8. The valve of claim 1, further comprising: a housing having a longitudinal cylindrical cavity in which the spool, the tube, and the thermal actuator are disposed.

9. The valve of claim 8, wherein the housing has a first cross-hole and a second crosshole, and wherein the valve further comprises: a port sleeve disposed within the housing and having (i) a respective first cross-hole aligned with the first cross-hole of the housing to form the reservoir port, and (ii) a respective second crosshole aligned with the second cross-hole of the housing to form the heat exchanger port.

10. The valve of claim 9, wherein the spool has a plurality of openings disposed in a circular array about the spool, wherein when the temperature of fluid is below the first threshold temperature, the plurality of openings partially overlap with the first cross-hole and the respective first cross-hole to form a flow area allowing fluid flow through the reservoir port, and wherein when the temperature of fluid exceeds the second threshold temperature and the spool moves, theplurality of openings partially overlap with the second cross-hole and the respective second crosshole to form a respective flow area allowing fluid flow through the heat exchanger port.

11. The valve of claim 8, further comprising: a main sleeve disposed partially with the housing, wherein the indicator pin is axially movable within the main sleeve, and wherein the tube is configured to slide about an exterior surface of the main sleeve.

12. A system comprising: a pump having a drain port from which case drain fluid of the pump is discharged; a fluid reservoir; a heat exchanger; and a valve comprising: a plurality of ports comprising: an inlet port that is fluidly coupled to the drain port of the pump, a reservoir port configured to be fluidly coupled to the fluid reservoir, and a heat exchanger port configured to be fluidly coupled to the heat exchanger, a spool that is axially movable, a tube that is coupled to the spool and axially movable therewith, a thermal actuator that is exposed to fluid received at the inlet port, wherein the thermal actuator applies a biasing force on the tube, and wherein the biasing force varies based on a temperature of fluid, and an indicator pin that is magnetically coupled to the tube such that as the tube moves, the indicator pin moves therewith, wherein when the temperature of fluid is below a firstthreshold temperature, the spool blocks the heat exchanger port and allows fluid received at the inlet port to flow to the reservoir port then to the fluid reservoir, and wherein when the temperature of fluid exceeds a second threshold temperature, the thermal actuator causes the tube and the spool to move, thereby causing the spool to block the reservoir port and allow fluid received at the inlet port to flow to the heat exchanger port to the heat exchanger, and wherein the indicator pin moves with the tube magnetically coupled thereto to provide a visual indication of whether fluid is provided to the heat exchanger.

13. The system of claim 12, wherein the thermal actuator comprises a thermally- sensitive spring applying the biasing force on the tube, wherein a shear modulus of the thermally- sensitive spring varies based on the temperature of fluid.

14. The system of claim 13, wherein the thermally-sensitive spring comprises a nitinol wire that is coiled to form the thermally-sensitive spring.

15. The system of claim 12, wherein the tube is magnetically coupled to the indicator pin via a magnet configuration comprising: a ring magnet mounted to the tube and surrounding the indicator pin; and a magnet assembly disposed within the indicator pin, coaxial with the ring magnet.

16. The system of claim 15, wherein the magnet assembly comprises: a first cylindrical magnet; a second cylindrical magnet; anda magnet spacer interposed between the first cylindrical magnet and the second cylindrical magnet.

17. The system of claim 16, wherein the first cylindrical magnet and the second cylindrical magnet have opposite poles facing each other, wherein the ring magnet has similar poles aligned with respective poles of the first cylindrical magnet and the second cylindrical magnet.

18. The system of claim 12, wherein the biasing force is a first biasing force applied on the tube in a distal direction, and wherein the valve further comprises: a biasing spring applying a second biasing force on the tube in a proximal direction, wherein when the temperature of fluid is below the first threshold temperature, the second biasing force is greater than the first biasing force, and wherein when the temperature of fluid exceeds the second threshold temperature, the first biasing force is greater than the second biasing force.

19. A method comprising: providing fluid from a case drain port of a pump to an inlet port of a valve, wherein the valve has a reservoir port fluidly coupled to a fluid reservoir, and a heat exchanger port fluidly coupled to a heat exchanger; when a temperature of fluid is below a first threshold temperature, causing a spool of the valve to block the heat exchanger port and allow fluid received at the inlet port to flow to the reservoir port;when the temperature of fluid exceeds a second threshold temperature, causing a thermal actuator of the valve to move the spool, thereby causing the spool to block the reservoir port and allow fluid received at the inlet port to flow to the heat exchanger port; and causing an indicator pin to move, via magnetic coupling, with the spool to provide a visual indication of whether fluid is provided through the heat exchanger port.

20. The method of claim 19, wherein the thermal actuator comprises a thermally- sensitive spring, wherein causing the thermal actuator to move the spool comprises: causing the thermally-sensitive spring to apply a biasing force that moves the spool.

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