System and method for operating a lubrication system with mechanical control

Abstract

A lubrication system comprises a heat exchanger with an inlet and an outlet, a gear lubrication circuit that fluidically connects a gear between the inlet and outlet of the heat exchanger, a stator lubrication circuit that fluidically connects a stator between the inlet and outlet of the heat exchanger, and a rotor lubrication circuit that fluidically connects a rotor between the inlet and outlet of the heat exchanger. The rotor lubrication circuit includes a mechanical rotor circuit valve located upstream of an inlet to the rotor and downstream of the outlet of the heat exchanger. Furthermore, the mechanical rotor circuit valve is configured to move from a closed position to an open position when a pressure immediately upstream of the mechanical rotor circuit valve reaches its opening pressure.

Description

Introduction

[0001] Electrified propulsion systems of motor vehicles and other mobile electrical systems comprise an electrical system configured to supply energy to one or more electric motors to generate drive torque. For example, an electric drive motor may be connected to the wheels of an electric vehicle, with the generated output torque being transmitted to the wheels to propel the electric vehicle along the road. For this purpose, a high-voltage bus of the electric vehicle is connected to a rechargeable energy storage system (RESS), the main component of which is a drive battery pack with a number and configuration of electrochemical battery cells appropriate for the application. The connection between the battery pack and the motor is made via an intermediate inverter module if the electric drive motor is a multiphase / alternating current (AC) motor.The electric vehicle's powertrain is configured as an alternating current (AC) machine. To cool and lubricate parts of the electric vehicle's powertrain, a lubrication system circulates a lubricant to the various components to perform at least one cooling or lubrication function.

[0002] US 2023 / 0287975A1 describes an electric drive module (EDM) configured to generate and transmit drive torque to a powertrain for propelling an electric vehicle. The EDM includes a gear assembly, an electric motor with a rotor and stator, and a thermal management system. The thermal management system includes a fluid circuit configured to supply fluid to the gear assembly, rotor, and stator, and a pump configured to circulate the fluid through the circuit. A valve is located on the fluid circuit and is configured to move selectively between a closed position, in which no fluid is supplied to the stator, and an open position, in which fluid is supplied to the stator for cooling.

[0003] DE 10 2022 210 957 A1 describes a temperature control device for a motor vehicle with a temperature control circuit and a first pump for circulating fluid in the temperature control circuit. The temperature control device includes an engine temperature control passage for temperature control of an electric motor of the motor vehicle, an electronics temperature control passage for temperature control of electronic components, an engine bypass passage that bypasses the engine temperature control passage, an electronics bypass passage that bypasses the electronics temperature control passage, and an actuator arrangement. The temperature control device includes a heat exchanger for temperature control of a second fluid by means of the first fluid circulated by the first pump.

[0004] DE 10 2019 123 981 A1 describes a clutchless electric vehicle with an electric motor for propelling the vehicle, a single-speed transmission, a differential, and a radiator. The single-speed transmission is cooled and lubricated via a hydraulic circuit containing hydraulic fluid. The hydraulic circuit includes an electrically driven pump for circulating the hydraulic fluid and control elements for regulating the flow of hydraulic fluid within the circuit. The control elements are configured such that the electric motor and the differential can be cooled and lubricated via the hydraulic circuit. Such a clutchless electric vehicle with a single-speed transmission enables simple and efficient cooling and lubrication.

[0005] DE 10 2023 200 684 A1 describes a supply system comprising a pump, to which a main supply line is connected and through which a liquid coolant can be conveyed into the main supply line, wherein the main supply line branches into a first partial supply line and a second partial supply line, of which the first partial supply line is connected to a stator cooling circuit and is provided for supplying the coolant to the stator cooling circuit, whereas the second partial supply line is connected to a rotor cooling circuit and serves to supply the coolant to the rotor cooling circuit. Description

[0006] According to the invention, a lubrication system for a vehicle is provided. The lubrication system comprises a heat exchanger with an inlet and an outlet, a transmission lubrication circuit that fluidically connects a transmission between the inlet and outlet of the heat exchanger, a stator lubrication circuit that fluidly connects a stator between the inlet and outlet of the heat exchanger, and a rotor lubrication circuit that fluidly connects a rotor between the inlet and outlet of the heat exchanger. The rotor lubrication circuit includes a mechanical rotor circuit valve that is arranged upstream of an inlet to the rotor and downstream of the outlet of the heat exchanger.Furthermore, the mechanical rotor circuit valve is configured to move from a closed position to an open position when a pressure immediately upstream of the mechanical rotor circuit valve reaches the opening pressure of the mechanical rotor circuit valve. The mechanical rotor circuit valve includes an offset ball valve configured to move from the closed position to an open position, allowing lubricant to flow to the rotor when a pressure in the rotor lubrication circuit exceeds the opening pressure of the mechanical rotor circuit valve.

[0007] In one aspect of the description, the mechanical rotor circuit valve includes either a spring-operated ball valve or a spring-operated pressure relief valve.

[0008] In one aspect of the description, the mechanical rotor recirculation valve includes an axis-displaced ball valve configured to move from an open position to a closed position when a centrifugal force caused by the rotation of the rotor on a ball in the axis-displaced ball valve is greater than the pressure immediately upstream of the mechanical rotor recirculation valve.

[0009] In one aspect of the description, the system includes a heat exchanger bypass passage configured to bypass the heat exchanger inlet and form a bypass connection with the rotor lubrication circuit downstream of the heat exchanger outlet.

[0010] In one aspect of the description, the heat exchanger bypass passage includes a mechanical bypass valve upstream of the mechanical rotor circuit valve, which remains in an open position until a bypass closing pressure is reached that is greater than the opening pressure of the mechanical rotor circuit valve.

[0011] In one aspect of the description, the rotor lubrication circuit includes a floating ball valve upstream of the mechanical rotor circuit valve and the bypass port.

[0012] In one aspect of the description, the heat exchanger bypass passage with the float ball valve has an opening pressure of the float ball valve that is lower than the bypass closing pressure.

[0013] In one aspect of the description, the gearbox lubrication circuit, the stator lubrication circuit and the rotor lubrication circuit are fluidically connected in parallel with an auxiliary lubrication circuit between the outlet of the heat exchanger and a sump.

[0014] In one aspect of the description, the stator lubrication circuit includes a stator opening with a maximum flow rate of the stator lubrication circuit, the gear lubrication circuit includes a gear opening with a maximum flow rate of the gear lubrication circuit, and the rotor lubrication circuit includes a rotor opening with a maximum flow rate of the rotor lubrication circuit.

[0015] In one aspect of the description, the rotor opening is located downstream of the mechanical rotor circuit valve.

[0016] In one aspect of the description, the system includes an electrically driven pump with a variable output flow rate, configured to direct lubricant from the gearbox lubrication circuit, the stator lubrication circuit, and the rotor lubrication circuit to an output of the electrically driven pump.

[0017] An example method for operating a lubrication system is described. The method includes directing a lubricant from a heat exchanger outlet to a stator lubrication circuit, directing the lubricant from the heat exchanger outlet to a gear lubrication circuit, and selectively directing the lubricant to a rotor lubrication circuit. The rotor lubrication circuit includes a mechanical rotor circuit valve upstream of a rotor, configured to block lubricant flow to the rotor when the lubricant pressure immediately upstream of the mechanical rotor circuit valve is lower than the valve's opening pressure.Furthermore, the mechanical rotor circuit valve is configured to be open when the lubricant pressure immediately upstream of the mechanical rotor circuit valve is greater than the opening pressure of the mechanical rotor circuit valve.

[0018] In one aspect of the description, the method involves guiding the lubricant through the lubrication system using an electrically driven pump with a variable output flow rate.

[0019] In one aspect of the description, the method involves diverting lubricant around the heat exchanger by means of a heat exchanger bypass passage that connects to the rotor lubrication circuit. The heat exchanger bypass passage includes a mechanical bypass valve located upstream of the mechanical rotor circuit valve, and the mechanical bypass valve has an opening pressure to move from an open to a closed position that is greater than the opening pressure of the mechanical rotor circuit valve.

[0020] In one aspect of the description, the procedure involves opening a floating ball valve located downstream of an outlet of the heat exchanger and upstream of the bypass connection with the heat exchanger bypass passage, at the opening pressure of the mechanical bypass valve.

[0021] In one aspect of the description, the mechanical rotor circuit valve includes either a spring-operated ball valve or a spring-operated pressure relief valve.

[0022] In one aspect of the description, the mechanical rotor circuit valve includes an axis-displaced ball valve.

[0023] An example vehicle is described. The vehicle comprises a passenger compartment, wheels supporting the passenger compartment, and a traction motor with a rotor and a stator, the rotor being configured to drive at least one of the plurality of wheels via a transmission and a lubrication circuit. The lubrication system comprises a heat exchanger with an inlet and an outlet, a transmission lubrication circuit fluidically connecting a transmission between the inlet and outlet of the heat exchanger, a stator lubrication circuit fluidically connecting a stator between the inlet and outlet of the heat exchanger, and a rotor lubrication circuit fluidically connecting a rotor between the inlet and outlet of the heat exchanger. The rotor lubrication circuit includes a mechanical rotor circuit valve located upstream of an inlet to the rotor and downstream of the outlet of the heat exchanger.Furthermore, the mechanical rotor circuit valve is configured to move from a closed position to an open position when a pressure immediately upstream of the mechanical rotor circuit valve reaches an opening pressure of the mechanical rotor circuit valve.

[0024] In one aspect of the description, the vehicle includes a heat exchanger bypass passage configured to bypass the heat exchanger inlet and connect to the rotor lubrication circuit downstream of the heat exchanger outlet, wherein the heat exchanger bypass passage includes a mechanical bypass valve upstream of the mechanical rotor circuit valve, and the mechanical bypass valve includes an opening pressure greater than the opening pressure of the mechanical rotor circuit valve to move from an open position to a closed position. Brief description of the drawings Fig. Figure 1 is a schematic representation of an example vehicle with an electric powertrain. Fig. Figure 2 is a schematic representation of an example lubrication system for the vehicle of Fig. 1 with multiple lubrication circuits. Fig. Figure 3 is a graphical representation of the flow rates in the individual lubrication circuits of Fig. 2 at different pressure levels in the lubrication system. Fig. Figure 4 is a schematic representation of an exemplary first valve arrangement of Fig. 2. Fig. Figure 5 is a schematic representation of another example of the first valve assembly of Fig. 2. Fig. Figure 6 is a schematic representation of another example of the first valve assembly of Fig. 2. Fig. Figure 7 is a schematic representation of another example of a lubrication system for the vehicle of Fig. 1 with multiple lubrication circuits. Fig. Figure 8 is a schematic representation of the flow rates in the individual lubrication circuits of Fig. 7 at different pressure levels in the lubrication system. Fig. Figure 9 shows a flowchart of an exemplary procedure for operating one of the lubrication circuits of Fig. 2 or Fig. 7.

[0025] The accompanying drawings are not necessarily to scale and may represent a somewhat simplified depiction of various preferred features of the present description, including, for example, certain dimensions, orientations, positions, and shapes. Details associated with such features are partly determined by the intended application and operating environment. Detailed description

[0026] Those with ordinary technical knowledge will recognize that terms such as "above," "below," "upwards," "downwards," "above," "below," "left," "right," etc., are used descriptively for the figures and do not represent limitations on the scope of the description as defined by the attached claims. Furthermore, the teachings may be described here in the form of functional and / or logical block components and / or various processing steps. It should be clear that such block components may comprise a set of hardware, software, and / or firmware components configured to perform the specified functions.

[0027] In the drawings, identical reference numbers refer to the same or similar components in the different illustrations. Fig. Figure 1 shows an electrical system 12, e.g., an electrified drive system of a motor vehicle 10 with a vehicle body 14 that defines a vehicle interior 42 or passenger compartment. The motor vehicle 10 of Fig. 1 comprises a charging receptacle (REC) connected to the electrical system 12. The motor vehicle 10 also includes wheels 44 for driving on the roadway. The wheels 44 can be driven by the electrical system 12 or be undriven / free-running, as described in more detail below.

[0028] The electrical system 12 comprises separate high-voltage and low-voltage buses. The high-voltage bus 20-H is electrically connected to a high-voltage battery assembly 13, e.g., a traction battery, and the low-voltage bus 20-L is electrically connected to an auxiliary battery (B). AUX30. At least one on-board charging module (OBCM) 22- includes inputs connected to the REC charging socket as a current converter to convert an AC power source from a charging station 48 into DC power at a socket to charge the battery pack assembly 13. At least one auxiliary power module (APM) 21 isolates the high-voltage bus 20-H from the low-voltage bus 20-L and has inputs connected to the high-voltage bus 20-H and outputs connected to the low-voltage bus 20-L to charge the auxiliary battery 30 and to operate vehicle accessories such as seat heating, power windows, or navigation systems. The OBCM 22 and the APM 21 are both connected to an electronic control unit 28 in the electrical system 12.

[0029] The electronic control unit 28 may include a computer and / or processor and comprise software, hardware, memory, algorithms, connections, etc., for managing and controlling the operation of the motor vehicle 10. As such, a method described below and generally referred to in Fig. Figure 5 is represented as a program or algorithm that can be partially set up on the controller 28. It should be noted that the controller 28 may include a device capable of analyzing data from the sensors, comparing data, making the necessary decisions to control the operation of the motor vehicle 10, and performing the necessary tasks to control the operation of the motor vehicle 10.

[0030] The controller 28 can be implemented as one or more digital computers or host machines, each comprising one or more processors, read-only memory (ROM), random-access memory (RAM), electrically-programmable read-only memory (EPROM), optical drives, magnetic drives, etc., a high-speed clock, an analog-to-digital (A / D) circuit, a digital-to-analog (D / A) circuit, an input / output (I / O) circuit, I / O devices and communication interfaces, and signal conditioning and buffering electronics. The computer-readable memory can comprise a non-volatile / tangible medium involved in providing data or computer-readable instructions. The memory can be non-volatile or volatile. Examples of non-volatile media include:Optical or magnetic hard disks and other permanent storage media. An example of volatile media is dynamic random-access memory (DRAM), which can represent main memory. Other forms of storage include, for example, a flexible disk, a hard disk, magnetic tape or other magnetic medium, a CD-ROM, a DVD and / or other optical medium, as well as other possible devices such as flash memory.

[0031] The control unit 28 comprises a tangible, non-volatile memory in which computer-executable instructions, including one or more algorithms, for controlling the operation of the motor vehicle 10 are stored. The algorithm(s) in question may, in particular, include an algorithm configured to optimize the energy consumption of the motor vehicle 10.

[0032] What the representative electrical system 12 of Fig. As regards Figure 1, the electrical system 12 is characterized by its separate high-voltage and low-voltage buses, designated “20-H” and “20-L” respectively. In embodiments where the electrical system 12 is part of the motor vehicle 10, for example, in an electric vehicle designed as a battery electric vehicle, a hybrid electric vehicle, or an extended-range electric vehicle, the term “high voltage” may encompass battery voltage capabilities of approximately 300 volts (V) or more. Such voltages are suitable for generating drive torques for vehicle propulsion functions and for supplying various high-voltage accessories on board the motor vehicle 10. The term “low voltage,” in turn, refers to auxiliary voltage levels typically of 12–50 V.Low-voltage lines (not shown) connect the low-voltage bus 20-L to one or more low-voltage accessories on board the motor vehicle 10, including but not limited to lighting, radio equipment, infotainment screens, sensors, etc.

[0033] In the exemplary embodiment of Fig. 1 The battery pack assembly 13 is selectively connected to and disconnected from a load via a series of high-voltage contactors 15. The applied load in the configuration shown comprises a DC link capacitor (C1), an inverter module (inverter) 16 with a plurality of semiconductor switches 17 connected to an electric traction motor (M) 18. In inverters such as the one in Fig. In the inverter 16 shown, several semiconductor switches 17 are used as fast-acting ON / OFF switching devices, e.g., insulated gate bipolar transistors (IGBTs), metal oxide semiconductor field-effect transistors (MOSFETs), thyristors, etc. In a typical three-phase configuration of the electric traction motor 18, the semiconductor switches 17 are turned on or off at predetermined switching intervals to deliver an alternating current (AC) waveform to the electric traction motor 18.

[0034] The in Fig. The electric traction motor 18 shown is connected to a rotatable output element 19, e.g., a motor shaft, and to a gearbox for driving the wheels 44. In the drive modes, the inverter 16 is controlled by pulse width modulation (PWM) or another application-appropriate switching control technique to energize the phase windings of the electric traction motor 18. As shown, the electric traction motor 18 is a multi-phase AC motor, in this case a three-phase machine. The rotation of the output element 19 ultimately transmits a torque (To) to a coupled load, including one or more wheels 44 of the motor vehicle 10.

[0035] Fig. Figure 2 shows an example of a lubrication system 100. In the example shown, the lubrication system 100 comprises a fluid outlet 104 that supplies a cooled lubricant to a rotor lubrication circuit 106 for the rotor of the motor M, an auxiliary lubrication circuit 108 that supplies cooled lubricant to auxiliary components within the drive unit d or the battery pack assembly 13, a stator lubrication circuit 110 of the motor M, or a transmission lubrication circuit 112 via a corresponding rotor lubrication circuit, auxiliary lubrication circuit, stator lubrication circuit, or transmission lubrication circuit. A pump 116 circulates the lubricant from a sump 115, which collects the lubricant from an outlet 114 of each of the lubrication circuits, which has a lower pressure than an inlet 117 to the heat exchanger 102 from the pump 116.In the example shown, pump 116 can be a mechanically driven pump or an electrically driven pump with a variable output flow rate. A feature of the electrically driven pump is that the lubricant flow rate can be controlled independently of the rotational power of the motor M.

[0036] In the example shown, the auxiliary lubrication circuit, the stator lubrication circuit, and the gear lubrication circuit are passively controlled by an auxiliary lubrication circuit opening 122, a stator lubrication circuit opening 124, and a gear lubrication circuit opening 126, respectively. Each of the openings 122, 124, and 126 can have a predetermined maximum flow rate, which is at least partially defined by the diameter of the openings 122, 124, and 126. Furthermore, each of the openings 122, 124, and 126 can result in different maximum flow rates for each of the circuits.

[0037] While the rotor lubrication circuit also includes a rotor lubrication circuit opening 120, the rotor lubrication circuit also includes a mechanical rotor circuit valve, such as a first valve assembly 118. In the example shown, the first valve assembly 118 is mechanically actuated based on the conditions of the lubrication system 100, so that it does not have an electrical actuator.

[0038] Fig. Figure 3 is a graphical representation 200 showing how the flow rate (Q) changes along the y-axis 204 for each circuit as the pressure (P) changes along the x-axis 202 at the outlet of the heat exchanger 102. For the stator lubrication circuit 110, the flow rate Q increases with pressure P up to a point 208 where a maximum flow rate is reached, determined by the opening 124 of the stator lubrication circuit. For the gear lubrication circuit 112, the flow rate Q increases with pressure P up to a point 212 where a maximum flow rate, determined by the opening 126 of the gear lubrication circuit, is reached. For the auxiliary lubrication circuit 108, the flow rate Q increases with pressure P up to a point 220 where a maximum flow rate, determined by the opening 122 of the auxiliary lubrication circuit, is reached.

[0039] Unlike the other lubrication circuits, the rotor lubrication circuit 106 limits the flow rate Q of the lubricant until a pressure P1 is reached at the outlet of the heat exchanger or immediately upstream of the first valve assembly 118. In the example shown, the pressure P1 corresponds to the opening pressure of the first valve assembly 118, e.g., the opening pressure of the mechanical rotor circuit valve. One advantage of limiting the flow rate Q in the rotor lubrication circuit 106 below the pressure P1 is that the temperature of the rotor core can rise while the pressure at the outlet of the heat exchanger 102 remains below the pressure P1. The load and speed of the motor M can be used as inputs to the controller 28 to determine a speed for operating the pump 116 when it is electrically driven. This controls the pressure in the lubrication system 100 to determine when the first valve assembly 118 opens and closes.

[0040] Increasing the rotor core temperature can increase the efficiency of motor M if the load is below a predetermined load threshold and the motor speed M is above a predetermined rotational speed threshold. As shown in Fig. As shown in Figure 3, the first valve assembly 118 limits the flow rate Q of the lubricant into the rotor lubrication circuit 106 until the pressure P1 is reached. Once the pressure P1 is reached at the outlet of the heat exchanger 102, the flow rate Q increases to a point 216 at which a maximum flow rate Q is reached, which is determined by the opening 120 of the rotor lubrication circuit.

[0041] Fig. Figure 4 is a schematic representation of a first valve type 118A for use as a first valve arrangement 118. In the example shown, the first valve type 118A comprises a spring-operated ball valve. The first valve type 118A includes a body section 127 that at least partially defines an inlet 121 which is in fluid communication with the outlet 104 of the heat exchanger 102. A ball 123 is movable in the direction of the arrow and is biased towards the inlet 121 by a spring 125. The spring 125 is configured such that it holds the ball 123 against the inlet 121 until the pressure in the outlet 104 of the heat exchanger 102 is greater than or equal to a pressure P1. As shown in Figure 4, the pressure in the first valve type 118A is a spring-operated ball valve. The first valve type 118A comprises a body section 127 which at least partially defines an inlet 121 that is in fluid communication with the outlet 104 of the heat exchanger 102. Fig. As shown in Figure 3, once the pressure P1 at the outlet 104 of the heat exchanger 102 is reached, the ball 123 moves along an arrow direction into an open position so that a flow rate Q can pass through an outlet 128 to the rotor lubrication circuit 106.

[0042] Fig. Figure 5 is a schematic representation of a second valve type 118B for use as a first valve arrangement 118. In the example shown, the second valve type 118B is a spring-operated pressure relief valve, for example, a spool valve. The second valve type 118B comprises a body section 130 with a first inlet 132 in fluid communication with the outlet 104 and a second inlet 138 in fluid communication with the outlet 104. The first inlet 132 feeds a chamber 134, which is biased against a spring 140 in a chamber with a spring-relieving outlet 142. The bias force of the spring 140 against the valve body 136 prevents lubricant from flowing through the second valve type 118B from the second inlet 138 to an outlet 144. The outlet 144 introduces the lubricant through the opening 120 of the rotor lubrication circuit into the rotor lubrication circuit 106, as shown in Fig. Figure 2 shows that in the illustrated example, the pressure of the lubricant in chamber 134 is sufficient to overcome the preload force of spring 140 as soon as the pressure at outlet 104 reaches pressure P1, so that the lubricant can flow through the second valve 118B to outlet 144.

[0043] Fig. Figure 6 is a schematic representation of a third valve type 118C for use as a first valve arrangement 118. In the example shown, the third valve type 118C is an offset ball valve. A feature of the offset ball valve is that it controls the lubricant flow rate through the rotor lubrication circuit 106 based on the lubricant pressure at the outlet 104 of the heat exchanger 102 or the rotational speed of the rotor 107 of the [unclear text]. Fig. 1 of the depicted motor M limited.

[0044] As in Fig. As shown in Figure 6, the rotor 107 of the motor M rotates about a central longitudinal axis A and includes an inner lubricant channel 152, which is at least partially defined by the rotor 107 and is in fluid communication with the outlet 104 of the heat exchanger 102. The third valve type 118C is located within the inner lubricant channel 152 and is configured to rotate with the rotor 107. The third valve type 118C includes a circumferential frame 156 with a radial outer surface that engages with a radial inner surface of the inner lubricant channel 152 and a radial inner surface that at least partially defines an inner passage through the third valve type 118C. The inner passage includes a housing 166 that defines an inlet 158 ​​at a first end and an outlet 160 at a second end.A sphere 164 is configured to move in the direction of the arrows depending on the fluid pressure and the rotational speed of the rotor 107. The direction of the arrows lies outside or perpendicular to the axis of rotation of the rotor 107. A spring 162 tensions the sphere 164 towards the inlet 158, so that the spring 162 can bear against the housing 166 and seal the inlet 158. Furthermore, one direction of the arrows extends along an axis O that deviates from or runs perpendicular to the axis of rotation A of the rotor 107.

[0045] During operation of the lubrication system 100, the third valve type 118C can restrict the lubricant flow if the rotational speed of the rotor 107 is sufficiently high to overcome a force on the ball 164 caused by pressure at the outlet 104 of the heat exchanger 102. Since the ball 164 moves along axis O, the rotational speed of the rotor 107 exerts a centrifugal force on the ball 164, which, in addition to the force exerted by the spring 162, pushes the ball 164 radially outward. Even if, for example, the pressure at the outlet 104 is sufficient to overcome the preload force of the spring 162, the centrifugal forces on the ball 164 caused by the rotation of the rotor 107 can cause the third valve type 118C to close.This can be the case, in particular, when the load on motor M is so low that the lubricant pressure at outlet 144 is insufficient to overcome the combined centrifugal and spring preload forces. However, if the load on motor M increases to a predetermined level requiring additional cooling, pump 116 increases the pressure at outlet 104 so that the combined spring and centrifugal forces can be overcome.

[0046] Fig. Figure 7 shows another example of a lubrication system 300. The lubrication system 300 is similar to the lubrication system 100, except as described below or illustrated in the drawings. Where components are similar or identical between the lubrication system 300 and the lubrication system 100, a leading "3" is inserted instead of the leading "1". One feature of the lubrication system 300 compared to the lubrication system 100 is the ability, under certain operating conditions, to route or bypass the lubricant around the heat exchanger to supply the rotor lubrication circuit.

[0047] In the illustrated example, the lubrication system 300 comprises a fluid outlet 304 that supplies a cooled lubricant to a rotor lubrication circuit 306 of the motor M, an auxiliary lubrication circuit 308 (such as a heating core or battery), a stator lubrication circuit 310 of the motor M, or a transmission lubrication circuit 312 for the gearbox GB via a corresponding rotor lubrication circuit, auxiliary lubrication circuit, stator lubrication circuit, or transmission lubrication circuit. A pump 316 circulates the lubricant from a sump 315, which collects the lubricant from an outlet 314 of each of the lubrication circuits. This outlet 314 has a lower pressure than an inlet 317 to the heat exchanger 302 from the pump 316. In the illustrated example, the pump 316 can be a mechanically driven pump or an electrically driven pump with a variable output flow rate.

[0048] In the example shown, the auxiliary lubrication circuit, the stator lubrication circuit and the gear lubrication circuit are passively managed with an auxiliary lubrication circuit opening 322, a stator lubrication circuit opening 324 and a gear lubrication circuit opening 326 respectively.

[0049] While the rotor lubrication circuit also includes a rotor lubrication circuit opening 320, it also features a first valve assembly 318 and a floating ball valve 321. A second valve assembly 319, e.g., a mechanical bypass valve, is fluidically connected to the rotor lubrication circuit between the first valve assembly 318 and the floating ball valve 321 via a bypass connection 325. In the illustrated example, the first valve assembly 318, the floating ball valve 321, and the second valve assembly 319 are mechanically actuated based on the conditions of the lubrication system 300, so the valves do not have an electrical actuator. In the illustrated example, the first valve assembly 318 can comprise one of the first, second, or third valve types 118A, 118B, or 118C described above.The floating ball valve 321 operates in a vertical orientation and uses gravity on a ball to prevent lubricant from the outlet 104 of the heat exchanger from entering the rotor lubrication circuit.

[0050] In the example shown, the second valve assembly 319 can be a piston or spool valve like the second valve 118B described above. Using the first valve assembly 318, the second valve assembly 319, and the floating ball valve 321, the lubrication system 300 can restrict the lubricant flow to the rotor lubrication circuit 306, the direct lubricant flow that has bypassed the heat exchanger 302, or the direct lubricant flow that has passed through the heat exchanger 302, based on the operating pressure of the lubricant at the outlet 304 of the heat exchanger 302.

[0051] In particular, the first valve assembly 318 remains closed until the pressure upstream of the first valve assembly 318 reaches the opening pressure P1. The second valve assembly 319 remains open until the pressure P2, e.g., a bypass closing pressure, is reached at the second valve assembly 319. Therefore, the lubricant bypasses the heat exchanger 302 between pressures P1 and P2 when it enters the rotor lubrication circuit 306. When the pressure at the second valve assembly 319 reaches P2, the second valve assembly 319 moves from the open to the closed position. When the second valve assembly 319 closes, it causes a pressure drop in the rotor circuit, which causes the float ball valve 321 to move from the closed to the open position, allowing cooled lubricant from the heat exchanger 302 to flow into the rotor lubrication circuit 306.

[0052] Fig. Figure 8 is a graphical representation 400 showing how the flow rate (Q) changes along the y-axis 404 for each circuit as the pressure (P) changes along the x-axis 402 at the outlet of the heat exchanger 302. For the stator lubrication circuit 310, the flow rate Q increases with the pressure P up to a point 408 where a maximum flow rate is reached, determined by the opening 324 of the stator lubrication circuit. For the gear lubrication circuit 312, the flow rate Q increases with the pressure P up to a point 412 where a maximum flow rate, determined by the opening 326 of the gear lubrication circuit, is reached. For the auxiliary lubrication circuit 308, the flow rate Q increases with the pressure P up to a point 420 where a maximum flow rate, determined by the opening 322 of the auxiliary lubrication circuit, is reached.

[0053] Unlike the other lubrication circuits, the rotor lubrication circuit 306 can limit the flow rate Q of the lubricant until a pressure P1 is reached upstream of the first valve assembly 318. A benefit of limiting the flow rate Q in the rotor lubrication circuit 306 below pressure P1 is that the rotor core temperature can increase, while a load on the motor M causes the pressure at the outlet of the heat exchanger 302 to be below P1. The increase in rotor core temperature can improve the efficiency of the motor M if the load is below a predetermined load threshold and the rotational speed is above a predetermined rotational speed threshold, as described above. Fig. As shown in Figure 8, the first valve arrangement 318 limits the flow rate Q of the lubricant into the rotor lubrication circuit 306 until the pressure P1 is reached. Once the pressure P1 is reached, the flow rate Q increases until a point 416 is reached, at which a maximum flow rate Q is reached, which is determined by the opening 320 of the rotor lubrication circuit.

[0054] As in Fig. As shown in Figure 8, no lubricant enters the rotor lubrication circuit 306 if the pressure upstream of the first valve assembly 318 is less than the pressure P1. In the example shown, the pressure P1 corresponds to the opening pressure of the first valve assembly 318.

[0055] As long as the pressure at the second valve assembly 319 is between pressure P1 and pressure P2, the lubricant bypasses the heat exchanger 302 via a heat exchanger bypass passage 323 and passes through both the first and second valve assemblies 318 and 319 to reach the rotor lubrication circuit 306. In this pressure range, the floating ball valve 321 remains closed, and only the lubricant that bypassed the heat exchanger 302 enters the rotor lubrication circuit 306. However, the auxiliary lubrication circuit 308, the stator lubrication circuit 310, and the gear lubrication circuit 312 continue to receive lubricant that has passed through the heat exchanger 302 from the outlet 304.

[0056] When the lubricant pressure at the second valve assembly 319 reaches pressure P2, the second valve assembly 319 moves from an open position to a closed position to block the flow of the diverted lubricant from the heat exchanger bypass passage 323 to the rotor lubrication circuit 306. Additionally, upon reaching pressure P2, a float ball valve opening pressure is reached for the float ball valve 321, causing the float ball valve 321 to move from a closed to an open position, allowing lubricant from the outlet 304 of the heat exchanger 302 to enter the rotor lubrication circuit 306. The float ball valve 321 moves to the open position due to the pressure drop in the rotor lubrication circuit when the second valve assembly 319 closes.

[0057] Fig.Figure 9 shows a flow diagram of an exemplary process 500 for operating one of the lubrication systems 100 or 300. Process 500 begins in block 502 with the supply of lubricant to the stator of motor M via the stator lubrication circuit. The flow rate Q of the lubricant to the stator depends on the openings 124 and 324 of the stator lubrication circuit. Process 500 then directs lubricant to gearbox GB via the transmission lubrication circuit 112 and 312 in block 504. The flow rate Q of the lubricant to gearbox GB depends on the openings 126 and 326 of the transmission lubrication circuit. Process 500 then directs the lubrication to the auxiliary lubrication circuit 108 or 308 in block 506. The flow rate Q of the lubricant to the auxiliary lubrication circuit 108 or 308 depends on the openings 124 and 324, respectively. Procedure 500 then transitions to block 508.

[0058] In block 508, the process selectively directs lubricant to the rotor lubrication circuit 106, 306. As described above, the rotor lubrication circuit only allows the lubricant to enter the rotor lubrication circuit 106, 306 when an opening pressure of the first valve assembly 118, 318 is reached. In the case of lubrication system 100, the lubricant reaching the rotor lubrication circuit 106 has passed through the heat exchanger 102. However, the lubricant reaching the rotor lubrication circuit 306 in lubrication system 300 may have either bypassed or passed through the heat exchanger 302, depending on the lubricant pressure at an outlet of the heat exchanger 302.

Claims

[1] Lubrication system (100) for a vehicle (10) comprising the following: a heat exchanger (102) with an inlet and an outlet; a transmission lubrication circuit (112) that fluidically connects a transmission between the inlet and outlet of the heat exchanger (102); a stator lubrication circuit (110) that fluidically connects a stator between the inlet and outlet of the heat exchanger (102); and a rotor lubrication circuit (106) which fluidically connects a rotor between the inlet and the outlet of the heat exchanger (102), wherein the rotor lubrication circuit (106) comprises a mechanical rotor circuit valve arranged upstream of an inlet to the rotor and downstream of the outlet of the heat exchanger (102), and the mechanical rotor circuit valve is configured to move from a closed position to an open position when a pressure immediately upstream of the mechanical rotor circuit valve reaches an opening pressure of the mechanical rotor circuit valve; wherein the mechanical rotor circuit valve comprises an axis-displaced ball valve configured to move from the closed position to an open position so that lubricant can flow to the rotor when a pressure in the rotor lubrication circuit (106) exceeds the opening pressure of the mechanical rotor circuit valve. [2] Lubrication system (100) according to claim 1, wherein the mechanical rotor circuit valve comprises either a spring-operated ball valve or a spring-operated pressure relief valve. [3] Lubrication system (100) according to claim 1, wherein the mechanical rotor circuit valve comprises an axis-displaced ball valve configured to move from an open position to a closed position when a centrifugal force on a ball in the axis-displaced ball valve caused by the rotation of the rotor is greater than the pressure immediately upstream of the mechanical rotor circuit valve. [4] Lubrication system (100) according to claim 1, comprising a heat exchanger bypass passage configured to bypass the inlet to the heat exchanger (102) and to form a bypass connection (325) with the rotor lubrication circuit (106) downstream of the outlet of the heat exchanger (102). [5] Lubrication system (100) according to claim 4, wherein the heat exchanger bypass passage comprises a mechanical bypass valve upstream of the mechanical rotor circuit valve which remains in an open position until a bypass closing pressure is reached which is greater than the opening pressure of the mechanical rotor circuit valve. [6] Lubrication system (100) according to claim 5, wherein the rotor lubrication circuit (106) comprises a floating ball valve (321) upstream of the mechanical rotor circuit valve and the bypass connection (325). [7] Lubrication system (100) according to claim 6, wherein the heat exchanger bypass passage with the floating ball valve (321) has an opening pressure of the floating ball valve (321) which is lower than the bypass closing pressure. [8] Lubrication system (100) according to claim 1, wherein the gear lubrication circuit (112), the stator lubrication circuit (110) and the rotor lubrication circuit (106) are fluidically connected in parallel with an auxiliary lubrication circuit (108) between the outlet of the heat exchanger (102) and a sump (115). [9] Lubrication system (100) according to claim 1, wherein the stator lubrication circuit (110) comprises a stator opening with a maximum flow rate of the stator lubrication circuit (110), the gear lubrication circuit (112) comprises a gear opening with a maximum flow rate of the gear lubrication circuit (112), and the rotor lubrication circuit (106) comprises a rotor opening with a maximum flow rate of the rotor lubrication circuit (106).

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