Pressure based dual piston rotor valve

Abstract

A valve including a body having an inlet port (412) and an outlet port (414). The body providing a flow path for oil from the inlet port to the outlet port. The valve including a spring-loaded piston (402, 404) having a spring (410) forcing the spring-loaded piston against a plug (407) for preventing oil from entering the spring-loaded piston and exiting through the outlet port when the valve is in a closed state, and different surfaces for interacting with a pressure applied by the oil to overcome the force of the spring and position the valve in an open state and maintain the position of the valve in the open state.

Description

PRESSURE BASED DUAL PISTON ROTOR VALVECLAIM FOR PRIORITY

[0001] This application claims the benefit of priority of U.S. Application Serial No. 63 / 604,002, filed November 29, 2023, which is hereby incorporated by reference in its entirety.FIELD

[0002] Some examples of this disclosure relate to a pressure based dual piston rotor valve.BACKGROUND

[0003] Electric vehicles (EVs) utilize valves to control the flow of liquid coolant flowing through the drivetrain. In these conventional configurations, however, the valve can be a costly and complex active component that requires electrical harnesses and active control of the valve piston by a vehicle controller.BRIEF DESCRIPTION OF THE DRAWINGS

[0004] So that the way the above-recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be made by reference to examples, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only examples of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective examples.

[0005] FIG. 1A shows a block diagram of oil flow within an EV drivetrain, according to an example of the present disclosure.

[0006] FIG. IB shows a flowchart of controlling oil flow within the EV drivetrain, according to an example of the present disclosure.

[0007] FIG. 2 shows a perspective view of the EV drivetrain, according to an example of the present disclosure.

[0008] FIG. 3 shows a perspective view of oil flow through the EV electric motor when using the rotor valve, according to an example of the present disclosure.

[0009] FIG. 4A shows a perspective view of oil flow through the rotor valve when the rotor valve is in the closed state, according to an example of the present disclosure.

[0010] FIG. 4B shows a perspective view of oil flow through the rotor valve when the rotor valve is in the open state, according to an example of the present disclosure.

[0011] FIG. 5 shows a data plot of oil pump flow versus oil temperature with respect to the rotor valve state, according to an example of the present disclosure.

[0012] FIG. 6 shows a flowchart of operating the oil pump to change the rotor valve state to control drivetrain temperature, according to an example of the present disclosure.DETAILED DESCRIPTION

[0013] Various examples of the present disclosure will now be described in detail with reference to the drawings. It should be noted that the relative arrangement of the components and steps, the numerical expressions, and the numerical values set forth in these examples do not limit the scope of the present disclosure unless it is specifically stated otherwise. The following description of at least one example is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or its uses. Techniques, methods, and apparatus as known by one of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. In all the examples illustrated and discussed herein, any specific values should be interpreted to be illustrative and non-limiting. Thus, other examples may have different values. Notice that similar reference numerals and letters refer to similar items in the following figures, and thus once an item is defined in one figure, it is possible that it need not be further discussed for the following figures. Below, the examples will be described with reference to the accompanying figures.

[0014] This disclosure is directed to a solution for providing passive spring- loaded dual piston valve having a design that can be placed into an open state or closed state in response to pressure of fluid at the valve inlet. Specifically, the system can control the fluid pump to increase fluid pressure to force the valve open when cooling is desired and decrease the pressure thereby allowing thespring force to close the valve when cooling is not desired. In addition, the dual piston design includes a small piston (e.g., relatively smaller than the other piston) that requires high pressure to initially open the valve, and a large piston (e.g., relatively larger than the other piston) that requires low pressure to maintain the valve in the open position. In other words, the small piston ensures that the valve stays closed unless the pressure exceeds a high pressure threshold, while the large piston allows lower pressure to be reduced to conserve energy while being sufficient for holding the valve open during operation.

[0015] The pistons are described herein using a spring-loaded design. However, it is noted that other biasing means (e.g., elastic materials, compressed gas, hydraulic fluid) may be utilized.

[0016] The valve is described herein in reference to deployment in a coolant system of an electric vehicle (EV). However, it is noted that the valve could be deployed in any system where fluid flow control is desired.

[0017] EV s are propelled by drivetrains that generally include an electric motor coupled to a gearbox. The electric motor may include supporting electronics such as a power inverter for inverting the direct current (DC) provided by the EV battery bank to alternating current (AC) and driving the electric motor with the AC power. The output of the inverter may be modified to control the speed at which the motor rotates. This may be accomplished by controlling the duty cycle of the AC power being applied to the electric motor. Upon receiving the AC power, the electric motor shaft rotates at the desired speed (e.g., speed dictated by the amplitude and duty cycle of the AC power). The rotating electric motor shaft, which is mechanically coupled to gears in a gearbox, turns the gears which may be part of a transmission (e.g., single speed transmission). The gearbox, which is mechanically coupled to a differential, may drive the differential to distribute power to the EV wheels. Of course, a differential may not be needed in certain configurations where the EV includes dual motors (e.g., each wheel is driven by an independent motor / gearbox). It is noted that the exact powertrain configuration may vary and may include a single electric motor or multiple electric motors for driving two or more of the EV wheels. For example, the powertrain configuration may drive the rear wheels of the EV via the gearbox and differential. In another example, a first powertrain may drive the rear wheels of the EV via a first gearboxand a first differential, and a second powertrain may drive the front wheels of the EV via a second gearbox and a second differential.

[0018] Regardless of the powertrain configuration employed by the EV, the drivetrain requires lubrication and cooling due to the heat, which may come from friction, resistive losses, and iron losses, generated by the rotation of the electric motor components and engagement of the gears within the gearbox. For example, an EV electric motor may rotate at extremely high speeds (e.g., up to 18,000 rpm). As the electric motor rotates, numerous components such as the shaft bearings for supporting the electric motor shaft produce significant heat that must be lubricated and cooled by a coolant fluid herein referred to as “oil.” The oil may be synthetic automatic transmission fluid (ATF) (e.g., Pentosin ATF 9®) that provides both good lubrication and heat transfer properties. In addition to the rotor bearings, other portions of the drivetrain, and in particular other portions of the electric motor may also benefit from oil cooling. For example, the electric motor may be a permanent magnet synchronous motor (PMSM) that utilizes embedded permanent magnets that magnetically interact with stator windings during operation of the electric motor. For example, during operation of the electric motor, AC power is applied to the stator windings which produce a rotating electro-magnetic (EM) field. This rotating EM field dictates the speed and direction of rotation of the rotor based on the interaction with the permanent magnets in the rotor. In other words, the rotating EM field creates push / pull forces (e.g., torques) with the permanent magnet which forces the rotor to rotate in a desired direction and at a desired speed. In response to the magnetic interaction between the stator windings and the permanent magnet, various factors such as Eddy Currents and Hysteresis cause the permanent magnet temperature to increase. This increase in temperature affects the flux produced by permanent magnets. Specifically, magnetic flux tends to decrease as temperature increases. In other words, the magnetic force produced by the permanent magnet weakens and therefore results in a weakened magnetic interaction between the stator windings and the permanent magnet. Therefore, the temperature of the magnets affects the performance (e.g., torque) of the motor and therefore the performance (e.g., acceleration) of the EV.

[0019] To ensure optimal EV performance, coolant (i.e., oil) may be injected into and circulated through the components of the electric motor during operation. Forexample, coolant channels may be formed in the rotor shaft and rotor laminations to allow the oil to flow through the motor to cool the bearings, rotor shaft and rotor magnets. The oil also flows through other components of the electric motor (e.g., stator components) and the gearbox (e.g., gears and bearings), thereby ensuring heat-controlled operation of the drivetrain.

[0020] Rather than utilizing an active oil valve including a solenoid controlled by the vehicle controller, the solution described herein replaces the active valve with a passive spring-loaded dual piston rotor valve that does not require electrical control / connections but is rather indirectly controlled based on the pressure of the oil in the system. In other words, the valve can be controlled by controlling the oil pump already present in the EV drivetrain. Benefits of the disclosed passive spring-loaded dual piston rotor valve include but are not limited to decreased valve cost, decreased valve complexity, increased valve dependability and ease of retrofitting, as existing drivetrain designs would not require modification other than eliminating the control cable to the valve which is no longer necessary.

[0021] FIG. 1A shows a block diagram 100 of an EV drivetrain and oil flow within the EV drivetrain. As shown in FIG. 1A, the EV drivetrain generally includes a stator housing 104 that houses an electric motor (e.g., permanent magnet synchronous motor (PMSM), AC induction motor) and a gearbox 102 that houses various gears and bearings for mechanically coupling the gearbox to the electric motor and to the differential for applying mechanical power to the EV wheels. In this example, the stator housing 104 and gearbox 102 may be mechanically coupled to each other and share a wet sump 108. In other words, the stator housing 104 and gearbox 102 may be part of an integrated drivetrain that supplies oil to the components either flowing through coolant channels or being sprayed by nozzles, collected by the wet sump and recirculated through the system in a continuous loop controlled by the oil pump.

[0022] In addition to the mechanical components, the drivetrain may include coolant channels and spray nozzles positioned at specific locations throughout the drivetrain to facilitate the lubrication and cooling of the mechanical components. For example, coolant channels may extend through the rotor shaft and rotor laminations of the electric motor, and through the stator laminations of the electric motor. A combination of coolant channels (not shown) and coolant spray nozzles(not shown) may also extend through the bearings and gears in the gearbox. In order to support flow and temperature control of the oil, the wet sump 108 is interfaced with an oil filter, a heat exchanger and a passive spring-loaded dual piston rotor valve. The oil filter and heat exchanger may be physically separate from the drivetrain, whereas the passive spring-loaded dual piston rotor valve may be located in the drivetrain housing (e.g., the end bell of the stator housing).

[0023] The EV contains a controller 116 and sensors 118 for controlling and monitoring operation of the drivetrain. Although the connections are not shown for clarity, controller 116 may be electrically coupled to the inverter and stator of the electric motor, to the oil pump 110, and to fans (not shown) of the heat exchanger. Similarly, sensors 118 may be pressure and temperature sensors placed inside or in proximity to mechanical components and cooling channels of the drivetrain and heat exchanger. Controller 116 may drive oil pump 110 to extract oil from wet sump 108 and inject the pressurized oil into an oil tube that feeds oil filter 112 and heat exchanger 114. Oil filter 112 filters any particulates from the oil, while heat exchanger 114 extracts and expels heat from the oil. Heat exchanger 114 may be thermally / fluidly coupled to the vehicle coolant which flows in a separate coolant channel through the heat exchanger. The vehicle coolant extracts the heat from the heat exchanger and then flows through the vehicle radiator that may be positioned in the front grill area of the EV. As the EV is operated, the heat from oil is absorbed by the heat exchanger 114. This heat is then absorbed from the heat exchanger into the vehicle coolant which then flows to the radiator and then to the air flowing over the radiator via convection and expelled out of the front grill of the EV.

[0024] Controller 116 may be the main vehicle controller or a sub-controller dedicated to controlling the drivetrain. Controller 116 may include various components such as a processor, memory, input / output interfaces, transceivers and the like. Controller 116 may be coupled to the electrical devices such as sensors 118, oil pump 110 and heat exchanger 114 via direct electrical connections or via a data bus (e.g., CAN bus). In either scenario, controller 116 executes software for monitoring temperatures of the drivetrain and controlling the various devices of the drivetrain based on the monitored temperatures.

[0025] In either case, the cooled oil exits the heat exchanger 114 and flows to various components of the electric motor in stator housing 104 and various gears and bearings within gearbox 102. For example, pressurized coolant may flow through spray nozzles (not shown) and pressurized coolant channels thermally coupled to gearbox components 103 such as mechanical bearings, gears and other components that may include but are not limited to a differential cross pin, windage tray, etc. In addition, pressurized coolant may flow through coolant channel 104 J of motor stator components such as stator laminations 1041 which may include end windings 104K and 104L, while being sprayed onto rotor bearings 104H.

[0026] In addition to these components, the pressurized coolant also flows to rotor valve 106A located in end bell 106. Rotor valve 106A controls the flow of the coolant into the motor rotor. When rotor valve 106A is in a closed state, the oil may either be blocked completely from flowing into the rotor or allowed to flow into the rotor at a low flow leak rate. In contrast, when the rotor valve 106A is in an open state, the oil may be free to flow through the motor rotor at full capacity. Specifically, when rotor valve 106A is controlled to be in the open state, the pressurized oil flows from rotor valve 106 A into input tube 104 A which feeds the oil into coolant channels that extend through rotor shaft 104B and spline 104C coupled to input gear 104D. When enough oil builds up in the coolant channels of rotor shaft 104B, the oil overflows thorough holes (not shown) in the rotor shaft 104B and flows through to channels 104F in rotor laminations 104E and eventually exiting the rotor laminations due to centrifugal force of the rotor. It is noted that channels 104F may be thermally coupled to rotor magnets 104G. This configuration allows the system to control the oil injected into the rotor, thereby extracting heat from the rotor shaft 104B and from rotor magnets 104G when desired. Of course, the flow of oil stops completely or may be reduced to the leak rate when the rotor valve 106A is controlled to enter the closed state.

[0027] FIG. IB shows a flowchart 150 of controlling oil flow within the EV electric motor. During operation, the controller monitors one or more temperatures in step 152. These temperatures may be the temperatures of the electric motor components themselves or the temperature of the oil flowing through the motor components which naturally correlates to the temperatures of the motor components. These temperatures may be determined by thermal modelthat estimates the temperatures from the rotor flux sensed in the motor stator windings by the inverter. For example, rotor flux and therefore temperature can be determined based on voltage and / or current detected in the stator. Alternatively, these temperature measurements may be facilitated by temperature sensors placed in contact with the motor components (e.g., rotor, magnets, etc.) or placed in contact with the coolant channels themselves. In either case, the controller compares the temperatures to a temperature threshold in step 154. If the measured temperature exceeds the threshold, then the controller activates the oil pump in step 156 to increase the pressure of the oil which results in the opening of the stator valve and the introduction of pressurized oil into the rotor shaft to facilitating cooling of the stator.

[0028] FIG. 2 shows a perspective view 200 of the exterior housing of the EV drivetrain. As shown in FIG. 2, the EV drivetrain includes gearbox housing 202B, electric motor housing 202A, oil filter 204 and output gear 206 which mechanically connects the gearbox to the EV differential (not shown) for driving the EV wheels. A cross-section line 208 is also shown in FIG. 2. Cross-section line 208 represents a cross-section of the drivetrain that is shown in more detail in FIG. 3. Specifically, cross-section line 208 represents a cross-section of the electric motor housing 202A which shows the rotor valve in fluid communication with the components of the electric motor.

[0029] FIG. 3 shows a perspective view 300 along the cross-section line 208 of oil flow through the EV rotor valve and electric motor. The EV rotor valve includes a small piston 301A and a large piston 301B that are mechanically coupled each other and held in the closed position by spring 302B (e.g., coil spring). As shown in FIG. 3, the small piston 301A is relatively smaller than the large piston 301B, and the large piston 301B is relatively larger than the small piston 30IA. Small piston 30IA at least partially blocks the opening of large piston 30IB. In other words, small piston 301 A prevents and / or allows oil to enter the valve body depending on the open / closed position of small piston 301 A.

[0030] During operation, oil flows through coolant pipe 304 A into valve inlet 302A. When the oil pressure is below a threshold pressure, herein referred to as “activation pressure”, the oil flows into the valve body but the pressure may not be strong enough to overcome the force exerted by spring 302B on the small piston301 A (i.e., the spring remains in a partially compressed resting state). Thus, small piston 301A remains in place preventing oil from entering the main backside opening of large piston 301B. Thus, the oil cannot flow through the valve to outlet tube 304B. In other words, when the oil pressure is below the activation pressure, the valve is in the closed state and oil cannot flow out of outlet and into the rotor shaft of the electric motor. However, when the oil pressure reaches the activation pressure, the force of the pressurized oil acts on small piston 301 A and overcomes the spring force of spring 302B (i.e., the spring is further compressed). This forces small piston 301A to move, and since small piston 301A and large piston 301B are mechanically coupled to one another, movement of small piston 301A translates to movement of large piston 301B away from the from the plug thereby exposing (i.e., revealing) the internal cavity of the large piston 301B. Once exposed, the oil flows through large piston 301B (which may be funnel shaped) and into the outlet tube 304B. As shown in FIG. 3, the large piston 301B includes an inlet aperture for receiving the oil from an inlet port and an outlet aperture for providing the oil to an outlet port with the outlet aperture being smaller than the inlet aperture. The oil then flows from outlet tube 304B into the coolant channel 306 A of rotor shaft 306. Once in coolant channel 306 A, the volume of oil increases and eventually exits the coolant channel via overflow holes 306B which are in fluid communication with coolant channels that run through rotor components 308, 310 and 312 which include the rotor magnets. After flowing through the coolant channel in the rotor laminations, the oil exits through a spray nozzle that sprays the coolant on rotor bearings 104H as shown in FIG. 1 A.

[0031] Effectively, the small piston 301A acts as a high-pressure gate to hold the valve closed with the aid of the coil spring force when the inlet pressure is low, and open when the inlet pressure is high, thereby exposing opening of large piston 301B to the pressurized oil. Since large piston 301B has a larger surface area than small piston 301 A, large piston 301B can be maintained in the open position with a lower oil pressure. It is noted that the small piston 301 A is mechanically coupled to large piston 301B, and therefore when small piston 301 A is activated, it moves large piston 301B to unseat large piston 301B from the plug, and when large piston 301B is activated after being unseated, the large piston 301B also holds small piston 301A in the open position.

[0032] Further details of the rotor valve are now described with reference to FIGs. 4 A and 4B. For example, FIG. 4 A shows a perspective view 400 of oil flow through the rotor valve when the rotor valve is in the closed state. As mentioned above, when the oil pump pressurizes the oil at a pressure below the activation pressure, the oil in inlet tube 412 presses on the surface of small piston 404 with a force that may not be strong enough to overcome the force of spring 410 holding large piston 402 against piston plug 407. A small amount of oil may still be able to enter the rotor valve body and leak along paths 416A and 416B into the internal volume of large piston 402 via leak holes (i.e., apertures). This effectively allows some of the oil to exit the valve and cool the rotor shaft. The activation pressure of the rotor valve may be dictated by the surface areas of small piston 404 and large piston 402. By utilizing a combination of a small piston 404 with a small surface area and a large piston 402 with a large surface area, the system effectively increases the activation pressure required to initially open the valve, while also reducing the pressure required to maintain the valve in the open position.

[0033] To open the valve, the oil is pumped into the valve inlet at or above the activation pressure. FIG. 4B shows a perspective view 450 of oil flow through the rotor valve when the rotor valve is in the open state. For example, when the controller determines that the rotor components (e.g., rotor shaft, bearings, magnets, etc.) needs to be cooled, the controller controls the pump to begin pumping the oil at an increased pressure. Once the pressure at the valve inlet reaches the activation pressure, oil pressure presses against the surface area of small piston 404 and overcomes the force of spring 410 which forces the large piston 402 to move linearly away from piston plug 407. Effectively, small piston 404 unseats large piston 402 from piston plug 407 thereby exposing the inner volume of large piston 402. Once exposed, a large volume of oil flows along path 418 through the body of large piston 402. This oil exerts a force that compresses spring 410 and exits the valve at outlet 408 and flows through outlet tube 414 and into the rotor. By exposing the inner volume of large piston 402, the surface area exposed to the pressurized oil also increases thereby requiring less pressure to keep the valve opened. Based on this configuration, once large piston 402 is unseated, the oil pressure can be reduced, and the valve maintains its opened state.

[0034] In other words, a high activation pressure may be initially needed to force the valve opened because the area of small piston 404 is small when in the closedstate. However, once small piston 404 forces large piston 402 to become unseated from the plug, the area of large piston 402 exposed to the oil increases and therefore the oil pressure does not need to be as high to hold the valve opened. Thus, during operation, the controller initially controls the oil pressure to achieve the activation pressure dictated by small piston 404 to open the valve, and then once the valve opens, the controller may control the pump to reduce the pressure to a holding pressure of large piston 402. The pressure may be reduced up until reaching a “deactivation pressure” which allows the valve to close. This deactivation pressure (which is less than the activation pressure) may be dictated by the spring force and the area of large piston 402 in contact with the oil. In other words, once the valve is opened, the pressure can be reduced as long as it does not reach the deactivation pressure, thereby holding the valve opened with less energy expenditure (i.e., reduced electrical consumption from the pump because the pump does not have to pump as hard).

[0035] FIG. 5 shows a data plot 500 of oil pump flow versus oil temperature with respect to the rotor valve state. As shown in FIG. 5, the activation pressure 502 for activating the valve (i.e., opening the valve) and the deactivation pressure 504 for deactivating the valve (i.e., closing the valve) are plotted with respect to the pump flow and the oil temperature. It is noted that the activation pressure 502 is greater than the deactivation pressure 504 regardless of oil temperature because when the valve is in the closed state, the surface area of small piston 404 is minimal thereby requiring more oil pressure to force the valve open, whereas when the valve is in the opened state, the surface area of large piston 402 is increased thereby requiring less oil pressure to maintain the valve in the opened state. It is also noted that as the oil temperature increases, both the activation pressure 502 and the deactivation pressure 504 also increase due to reduced viscosity of the oil, thereby requiring higher pump flow to open the valve and maintain the valve in the opened position respectively.

[0036] Overall operation of the coolant system is now described with reference to FIG. 6 which shows a flowchart 600 of operating the oil pump to control the rotor valve state to control drivetrain temperature. In step 602, the controller monitors the drivetrain temperatures. These temperatures may include temperatures of the rotor shaft and / or rotor magnets or the oil temperature correlating to the temperatures of the rotor shaft and / or rotor magnets. As noted above, thesetemperatures may be measured by temperature sensors placed within the rotor components themselves or within channels of the oil path (e.g., input tube, output tube, valve, etc.). Alternatively, the temperatures may be estimated from the rotor flux sensed in the motor stator windings by the inverter. For example, rotor flux and therefore temperature can be determined based on voltage and / or current detected in the stator. In other words, the controller could use a numerical model for determining motor component temperatures based on predetermined heat losses at speed / torque / voltage values, etc. In either case, the monitored temperature may be compared to a threshold in step 604. This threshold may be based on various factors including but not limited to a safety temperature range (e.g., predetermined temperature range) of the motor, safety thresholds, efficiency thresholds, driving modes, motor life, etc. If the temperature is not greater than the threshold, the controller may deactivate or maintain the current oil pump operation in step 608. In other words, when the temperature has not reached a point of interest where cooling may be needed, the coolant system does not have to increase oil flow. However, if the monitored temperature is greater than the threshold, the controller, in step 606, may increase oil pump output (flow rate) to increase the oil pressure at the inlet of the rotor valve. This increased pressure may coincide with the known activation pressure of the small piston of the rotor valve. After increasing the pump pressure, in step 610, the controller may determine if the valve is opened or not. This may be determined based on whether the controller observes a sudden drop in pressure caused by the large piston becoming unseated from the plug. If the valve is not opened, then the controller may increase the pressure in step 614 and repeat the process until the valve is determined to have opened (i.e., a pressure drop is observed). Once the controller determines that the valve has opened, the controller, in step 612, may decrease oil pump output (flow rate) to reduce the oil pressure from the activation pressure down to a lower pressure that may be sufficient to hold the valve opened while avoiding dropping below the deactivation pressure of the valve. While being maintained in the open position, the controller may compare the temperature to a deactivation temperature (e.g., desired temperature, predetermined temperature) in step 615. If the temperature is not less than the deactivation temperature, the controller continues to maintain the valve in the open position. If the temperature is less than the deactivation temperature, the controller deactivates the pump instep 616 at which point the spring force overcomes the force exerted by the oil pressure thereby closing the valve. In other words, once the large piston becomes unseated from the plug and the oil begins to flow into the rotor shaft, pressure produced by the pump can be reduced from activation pressure 502 while staying above deactivation pressure 504 in FIG. 5. Optimally, the controller may control the pump to reduce the oil pressure as close as possible to the deactivation pressure 504 without reaching deactivation pressure 504. This ensures that the energy consumed by the pump may be minimized while sufficiently cooling the motor.

[0037] In addition to temperature, the controller may control the opening / closing of the valve based on other feedback such as motor torque and motor speed. For example, parameters such as motor torque and speed may be monitored at step 602 and then utilized in steps 604 and 614 with respective torque and speed thresholds to determine whether the pump pressure should be decreased or increased. In other words, the controller may make improved decisions by considering various operating parameters of the motor.

[0038] The activation temperature and deactivation temperature may be set based on various factors including but not limited to safety thresholds (e.g., mechanical failure temperatures), efficiency thresholds (e.g., motor efficiency) and driving modes to name a few. For example, the controller may store temperature thresholds related to motor efficiency and driving modes. These thresholds may be set to hold the electric motor temperature at an ideal temperature value or temperature range (e.g., predetermined temperature range) for efficient and safe operation of the electric motor. In some scenarios, a decrease in motor temperature may be desired, while in other scenarios, an increase in motor temperature may be desired. For example, when high efficiency is desired, the controller may control the valve to increase the motor temperature thereby reducing the motor flux. In another example, when high peak torque is desired, the controller may control the valve to decrease the motor temperature thereby increasing the motor flux. In other words, the controller can control flux and therefore control performance as desired.

[0039] While the rotor valve has been described in the context of controlling oil flow to the rotor of an EV electric motor, it is noted that the valve may be used in other applications. In other words, the valve disclosed herein can act as a valvefor supplying fluids to other types of mechanical components and systems. Installation of the valve in those systems may be dependent on the specific technical constraints of the systems but will ultimately be controlled in a similar manner by increasing fluid pressure at the valve input to force the small piston to open the valve and decreasing fluid pressure at the valve input to efficiently maintain the large piston in the open position. Of course, the pressure may be decreased even further to allow the valve to close when needed. In other words, the valve can be efficiently opened, maintained open, and then closed by controlling the pump pressure and without actively controlling the valve itself.

[0040] Benefits of the disclosed valve includes reduced manufacturing cost and ease of installation due to reduced complexity. As mentioned above, the valve includes a passive spring-loaded dual piston that does not require the electrical control. Thus, less components may be required to manufacture the valve (i.e., piston body and spring). In addition, since the valve does not require electrical control, an electrical harness (required by active solenoid driven valves) may be eliminated from the manufacturing and installation process. In other words, once the valve is installed in the drivetrain housing and connected the fluid lines, the installation process is complete.EXAMPLES

[0041] Thus, the present disclosure includes one or more of the following examples.

[0042] Example l is a valve comprising: a body including an inlet port and an outlet port, the body providing a flow path for oil from the inlet port to the outlet port; and a spring-loaded piston comprising: a spring forcing the spring-loaded piston against a plug for preventing oil from entering the spring-loaded piston and from exiting through the outlet port when the valve is in a closed state; and surfaces for interacting with a pressure applied by the oil to overcome a force of the spring, to position the valve in an open state, and to maintain the valve in the open state.

[0043] In Example 2, the subject matter of Example 1 further comprises a first surface of the surfaces requiring a first pressure being applied by the oil at the inlet port to overcome the force of the spring and to position the valve in the open state; and a second surface of the surfaces requiring a secondpressure being applied by the oil at the inlet port to maintain the valve in the open state.

[0044] In Example 3, the subject matter of Example 2 further comprises wherein the second surface is larger than the first surface, the second pressure being less than the first pressure.

[0045] In Example 4, the subject matter of any one of Examples 1-3 further comprises a first piston of the spring-loaded piston; and a second piston of the spring-loaded piston, the second piston being larger than the first piston, the first piston and second piston being mechanically coupled to one another.

[0046] In Example 5, the subject matter of Example 4 further comprises a first surface of the surfaces provided on the first piston and facing the inlet port when the valve is in the closed state.

[0047] In Example 6, the subject matter of Example 4 further comprises a second surface of the surfaces provided on the second piston and facing the inlet port when the first piston is activated.

[0048] In Example 7, the subject matter of any one of Examples 1-6 further comprises leak apertures in the spring-loaded piston allowing a predetermined flow of oil to enter the spring-loaded piston and to exit through the outlet port when the valve is in the closed state.

[0049] In Example 8, the subject matter of any one of Examples 1-7 further comprises a main aperture in the spring-loaded piston closed by the plug when the valve is in the closed state, and revealed when the valve is in the open state allowing the oil to flow through the spring-loaded piston and to exit through the outlet port.

[0050] In Example 9, the subject matter of any one of Examples 1-8 further comprises wherein the spring-loaded piston has a funnel shape with an inlet aperture for receiving the oil from the inlet port and an outlet aperture for providing the oil to the outlet port, the outlet aperture being smaller than the inlet aperture.

[0051] In Example 10, the subject matter of any one of Examples 1-9 further comprises wherein the spring is a coil spring between the spring-loaded piston and the outlet port, the spring being compressed by movement of the spring-loaded piston when the valve is in the open state.

[0052] Example 11 is a method of controlling a valve comprising: controlling, by a processor, an oil pump to pump oil at a first pressure into an inlet port of a valve including a body having the inlet port and an outlet port, the body providing a flow path for the oil from the inlet port to the outlet port by way of a spring-loaded piston including a spring forcing the spring-loaded piston against a plug for preventing the oil from entering the spring-loaded piston and from exiting through the outlet port, the first pressure acting on a first surface of the spring-loaded piston to overcome a force of a spring and to position the valve in an open state; and controlling, by the processor, the oil pump to pump the oil at a second pressure into an inlet port of the valve, the second pressure acting on a second surface of the spring-loaded piston to maintain position the valve in an open state, wherein the second surface is larger than the first surface resulting in the second pressure being less than the first pressure.

[0053] In Example 12, the subject matter of Examples 11 further comprises determining, by the processor, a temperature of an electric vehicle drivetrain coupled to the inlet port and the outlet port of the valve; and controlling, by the processor, the oil pump to pump the oil based on the temperature of the electric vehicle drivetrain.

[0054] In Example 13, the subject matter of any one of Examples 11-12 further comprises controlling, by the processor, the oil pump to pump the oil at the first pressure when the temperature of the electric vehicle drivetrain exceeds a threshold.

[0055] In Example 14, the subject matter of any one of Examples 11-13 further comprises determining, by the processor, a temperature of the oil; and controlling, by the processor, the first pressure and the second pressure based on the temperature of the oil.

[0056] In Example 15, the subject matter of Example 14 further comprises increasing, by the processor, the first pressure and the second pressure when the temperature of the oil is greater than a temperature threshold; and decreasing, by the processor, the first pressure and the second pressure when the temperature of the oil is less than the temperature threshold.

[0057] In Example 16, the subject matter of any one of Examples 11-15 further comprises controlling, by the processor, the oil pump to pump the oil at the first pressure into the inlet port of a valve; monitoring, by the processor, pressure at the valve and comparing the pressure at the valve to a pressure drop threshold indicating that the valve has entered the open state; and controlling, by the processor, the oil pump to pump the oil at the second pressure into the inlet port of the valve in response to the pressure at the valve dropping below the pressure drop threshold.

[0058] In Example 17, the subject matter of Example 12 further comprises determining, by the processor, a temperature of rotor magnets of an electric motor of the electric vehicle drivetrain; and controlling, by the processor, the oil pump to pump the oil based on the temperature of the rotor magnets of the electric motor.

[0059] In Example 18, the subject matter of Example 12 further comprises controlling, by the processor, the oil pump to pump the oil through the electric vehicle drivetrain to maintain the temperature of the electric vehicle drivetrain in a predetermined temperature range.

[0060] In Example 19, the subject matter of Example 18 further comprises adjusting, by the processor, the predetermined temperature range based on a driving scenario or driving mode of an electric vehicle.

[0061] In Example 20, the subject matter of Example 12 further comprises controlling, by the processor, the oil pump to pump the oil through the outlet port to a rotor shaft, to rotor magnets of an electric motor, and to the inlet port.

[0062] It should be noted that the description and the figures above merely illustrate the principles of the present subject matter along with examples described herein and should not be construed as a limitation to the present subject matter. It is thus understood that various arrangements may be devised that although not explicitly described or shown herein, embody the principles of the present subject matter. Moreover, all statements herein reciting principles, aspects, and implementations of the present subject matter, as well as specific examples thereof, are intended to encompass equivalents thereof.

[0063] It is to be understood that not necessarily all objects or advantages may be achieved in accordance with any particular example described herein. Thus, forexample, those skilled in the art will recognize that some examples may be operated in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.

[0064] All of the processes described herein may be embodied in, and fully automated via, software code modules executed by a computing system that includes computers or processors. The code modules may be stored in any type of non-transitory computer-readable medium or other computer storage device. Some or all of the methods may be embodied in specialized computer hardware.

[0065] Many other variations than those described herein will be apparent from this disclosure. For example, depending on the example, some acts, events, or functions of any of the algorithms described herein can be performed in a different sequence, can be added, merged, or left out altogether (for example, not all described acts or events are necessary for the practice of the algorithms). Moreover, in some examples, acts or events can be performed concurrently, for example, through multi -threaded processing, interrupt processing, or multiple processors or processor cores, or on other parallel architectures, rather than sequentially. In addition, different tasks or processes can be performed by different machines and / or computing systems that can function together.

[0066] The various illustrative logical blocks and modules described in connection with the examples disclosed herein can be implemented or performed by a machine, such as a processing unit or processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A processor can be a microprocessor, but in the alternative, the processor can be a controller, microcontroller, or state machine, combination of the same, or the like. A processor can include electrical circuitry to process computer-executable instructions. In some examples, a processor includes an FPGA or other programmable device that performs logic operations without processing computer-executable instructions. A processor can also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, microprocessors in conjunction with a DSP core, or any other such configuration.

[0067] Although described herein primarily with respect to digital technology, a processor may also include primarily analog components. A computing environment can include any type of computer system, including, but not limited to, a computer system based on a microprocessor, a mainframe computer, a digital signal processor, a portable computing device, a device controller, or a computational engine within an appliance, to name a few. The elements of a method, process, routine, or algorithm described in connection with the examples disclosed herein can be implemented directly in hardware, in a software module executed by a processor device, or in a combination of the two. A software module can reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of a non-transitory computer-readable storage medium. An example storage medium can be coupled to the processor device such that the processor device can read information from, and write information to, the storage medium. In the alternative, the storage medium can be integral to the processor device. The processor device and the storage medium can reside in an ASIC. The ASIC can reside in a user terminal. In the alternative, the processor device and the storage medium can reside as discrete components in a user terminal.

[0068] The processes described herein or illustrated in the figures of the present disclosure may begin in response to an event, such as on a predetermined or dynamically determined schedule, on demand when initiated by a user or system administrator, or in response to some other event. When such processes are initiated, a set of executable program instructions stored on one or more non- transitory computer-readable media (e.g., hard drive, flash memory, removable media, etc.) may be loaded into memory (e.g., RAM) of a server or other computing device. The executable instructions may then be executed by a hardware-based computer processor of the computing device. In some examples, such processes or portions thereof may be implemented on multiple computing devices and / or multiple processors, serially or in parallel.

[0069] Although the described flow diagrams herein can show operations as a sequential process, many of the operations can be performed in parallel or concurrently. In addition, the order of the operations may be re-arranged. A process is terminated when its operations are completed. A process may correspond to a method, a procedure, an algorithm, etc. The operations of methodsmay be performed in whole or in part, may be performed in conjunction with some or all of the operations in other methods, and may be performed by any number of different systems, such as the systems described herein, or any portion thereof, such as a processor included in any of the systems.

[0070] Conditional language such as, among others, “can,” “could,” “might” or “may,” unless specifically stated otherwise, are otherwise understood within the context as used in general to convey that some examples include, while other examples do not include, some features, elements and / or steps. Thus, such conditional language is not generally intended to imply that features, elements and / or steps are in any way for examples or that examples necessarily include logic for deciding, with or without user input or prompting, whether these features, elements and / or steps are included or are to be performed in any particular example.

[0071] Disjunctive language such as the phrase “at least one of X, Y, or Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to present that an item, term, etc., may be either X, Y, or Z, or any combination thereof (for example, X, Y, and / or Z). Thus, such disjunctive language is not generally intended to, and should not, imply that some examples require at least one of X, at least one of Y, or at least one of Z to each be present.

[0072] Any process descriptions, elements or blocks in the flow diagrams described herein and / or depicted in the attached figures should be understood as potentially representing modules, segments, or portions of code which include executable instructions for implementing specific logical functions or elements in the process. Alternate examples are included within the scope of the examples described herein in which elements or functions may be deleted, executed out of order from that shown, or discussed, including substantially, concurrently, or in reverse order, depending on the functionality involved as would be understood by those skilled in the art.

[0073] It should be emphasized that many variations and modifications may be made to the above-described examples, the elements of which are to be understood as being among other acceptable examples. All such modifications and variations are intended to be included herein within the scope of this disclosure.

[0074] Any process descriptions, elements or blocks in the flow diagrams described herein and / or depicted in the attached figures should be understood aspotentially representing modules, segments, or portions of code which include executable instructions for implementing specific logical functions or elements in the process. Alternate implementations are included within the scope of the examples described herein in which elements or functions may be deleted, executed out of order from that shown, or discussed, including substantially concurrently or in reverse order, depending on the functionality involved as would be understood by those skilled in the art.

[0075] Unless otherwise explicitly stated, articles such as “a” or “an” should generally be interpreted to include one or more described items. Accordingly, phrases such as “a device configured to” are intended to include one or more recited devices. Such one or more recited devices can also be collectively configured to carry out the stated recitations. For example, “a processor configured to carry out recitations A, B, and C” can include a first processor configured to carry out recitation A working in conjunction with a second processor configured to carry out recitations B and C.

[0076] It will also be appreciated that one or more of the elements depicted in the drawings / figures can also be implemented in a more separated or integrated manner, or even removed or rendered as inoperable in certain cases, as is useful in accordance with a particular application.

Claims

What is claimed is:

1. A valve comprising: a body including an inlet port and an outlet port, the body providing a flow path for oil from the inlet port to the outlet port; and a spring-loaded piston comprising: a spring forcing the spring-loaded piston against a plug for preventing oil from entering the spring-loaded piston and from exiting through the outlet port when the valve is in a closed state; and one or more surfaces for interacting with a pressure applied by the oil to overcome a force of the spring, to position the valve in an open state, and to maintain the valve in the open state.

2. The valve of claim 1, comprising: a first surface of the one or more surfaces requiring a first pressure being applied by the oil at the inlet port to overcome the force of the spring and to position the valve in the open state; and a second surface of the one or more surfaces requiring a second pressure being applied by the oil at the inlet port to maintain the valve in the open state.

3. The valve of claim 2, wherein the second surface is larger than the first surface, the second pressure being less than the first pressure.

4. The valve of claim 1, comprising: a first piston of the spring-loaded piston; and a second piston of the spring-loaded piston, the second piston being larger than the first piston, the first piston and second piston being mechanically coupled to one another.

5. The valve of claim 4, comprising: a first surface of the one or more surfaces provided on the first piston and facing the inlet port when the valve is in the closed state.

6. The valve of claim 4, comprising:a second surface of the one or more surfaces provided on the second piston and facing the inlet port when the first piston is activated.

7. The valve of claim 1, comprising: leak apertures in the spring-loaded piston allowing a predetermined flow of oil to enter the spring-loaded piston and to exit through the outlet port when the valve is in the closed state.

8. The valve of claim 1, comprising: a main aperture in the spring-loaded piston closed by the plug when the valve is in the closed state, and revealed when the valve is in the open state allowing the oil to flow through the spring-loaded piston and to exit through the outlet port.

9. The valve of claim 1, wherein the spring-loaded piston has a funnel shape with an inlet aperture for receiving the oil from the inlet port and an outlet aperture for providing the oil to the outlet port, the outlet aperture being smaller than the inlet aperture.

10. The valve of claim 1, wherein the spring is a coil spring between the spring-loaded piston and the outlet port, the spring being compressed by movement of the spring-loaded piston when the valve is in the open state.

11. A method of controlling a valve comprising: controlling, by a processor, an oil pump to pump oil at a first pressure into an inlet port of a valve including a body having the inlet port and an outlet port, the body providing a flow path for the oil from the inlet port to the outlet port by way of a spring-loaded piston including a spring forcing the spring-loaded piston against a plug for preventing the oil from entering the spring-loaded piston and from exiting through the outlet port, the first pressure acting on a first surface of the spring-loaded piston to overcome a force of a spring and to position the valve in an open state; and controlling, by the processor, the oil pump to pump the oil at a second pressure into an inlet port of the valve, the second pressure acting on a second surface of the spring-loaded piston to maintain position the valve in an open state, wherein the second surface is larger than the first surface resulting in the second pressure being less than the first pressure.

12. The method of claim 11, comprising: determining, by the processor, a temperature of an electric vehicle drivetrain coupled to the inlet port and the outlet port of the valve; and controlling, by the processor, the oil pump to pump the oil based on the temperature of the electric vehicle drivetrain.

13. The method of claim 12, comprising: controlling, by the processor, the oil pump to pump the oil at the first pressure when the temperature of the electric vehicle drivetrain exceeds a threshold.

14. The method of claim 11, comprising: determining, by the processor, a temperature of the oil; and controlling, by the processor, the first pressure and the second pressure based on the temperature of the oil.

15. The method of claim 14, comprising: increasing, by the processor, the first pressure and the second pressure when the temperature of the oil is greater than a temperature threshold; and decreasing, by the processor, the first pressure and the second pressure when the temperature of the oil is less than the temperature threshold.

16. The method of claim 11, comprising: controlling, by the processor, the oil pump to pump the oil at the first pressure into the inlet port of a valve; monitoring, by the processor, pressure at the valve and comparing the pressure at the valve to a pressure drop threshold indicating that the valve has entered the open state; and controlling, by the processor, the oil pump to pump the oil at the second pressure into the inlet port of the valve in response to the pressure at the valve dropping below the pressure drop threshold.

17. The method of claim 12, comprising:determining, by the processor, a temperature of rotor magnets of an electric motor of the electric vehicle drivetrain; and controlling, by the processor, the oil pump to pump the oil based on the temperature of the rotor magnets of the electric motor.

18. The method of claim 12, comprising: controlling, by the processor, the oil pump to pump the oil through the electric vehicle drivetrain to maintain the temperature of the electric vehicle drivetrain in a predetermined temperature range; and adjusting, by the processor, the predetermined temperature range based on a driving scenario or driving mode of an electric vehicle.

19. The method of claim 12, comprising: controlling, by the processor, the oil pump to pump the oil through the outlet port to a rotor shaft, to rotor magnets of an electric motor, and to the inlet port.

20. A piston coupled to a valve with an inlet port and an outlet port, the piston comprising: a biasing means forcing the piston against a plug for preventing oil from entering the piston and from exiting through the outlet port when the valve is in a closed state; and one or more surface for interacting with a pressure applied by the oil to overcome a force of the biasing means, to position the valve in an open state, and to maintain the valve in the open state.

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