Vehicle drive unit

Abstract

According to the present invention, a control device performs first discharge control for causing a pump to operate for a prescribed first discharge time (T1) on the condition that a main power source has been switched from OFF to ON and the vehicle speed has reached at least a prescribed vehicle speed threshold value (Vx).

Description

[Technical Field]

[0001] The present invention relates to a vehicle drive device mounted on an electric vehicle. [Background technology]

[0002] An example of such a vehicle drive device is disclosed in Japanese Patent Laid-Open Publication No. 2022-154736 (Patent Document 1).

[0003] In the vehicle drive system described in Patent Document 1, the electric oil pump is operated at maximum output when the power is turned on, thereby supplying oil to the bearings provided inside the drive system and preventing the bearings from becoming insufficiently lubricated when the power is turned on. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-154736 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the above-described vehicle drive system, the electric oil pump is operated at maximum output each time the power is turned on. This tends to increase the power consumption required to operate the electric oil pump, reducing the energy efficiency of the drive system as a whole. Furthermore, operating the electric oil pump at maximum output upon power start-up tends to increase the load on the electric oil pump, shortening its lifespan. Furthermore, using an electric oil pump designed to withstand such loads tends to increase the cost of the electric oil pump.

[0006] Therefore, it is desirable to realize a vehicle drive device that can ensure the required product life while suppressing costs and that can easily improve energy efficiency. [Means for solving the problem]

[0007] A vehicle drive device mounted on an electric vehicle, a rotating electric machine having a rotor as a driving force source for the wheels; a case that accommodates the rotating electrical machine and oil; a pump driven by a drive source different from the rotary electric machine, which sucks and discharges oil from inside the case; an oil supply passage that supplies the oil discharged by the pump to at least a rotor bearing that rotatably supports the rotor; a control device for controlling the pump; Equipped with the control device includes a power supply state acquisition unit that acquires information indicating an on / off state of a main power supply of the electric vehicle, and a vehicle speed acquisition unit that acquires information indicating a vehicle speed of the electric vehicle; The control device executes a first discharge control that operates the pump for a predetermined first discharge time on the condition that the main power supply has been turned on from off and the vehicle speed has become equal to or greater than a predetermined vehicle speed threshold.

[0008] According to this configuration, the conditions for operating the pump through the first discharge control include not only the main power supply being switched from off to on, but also the vehicle speed being equal to or greater than the vehicle speed threshold. In other words, the pump does not necessarily operate when the power supply is turned on, but only when the vehicle speed is at a certain high level. Therefore, the operating time of the pump can be reduced. This reduces the energy consumption caused by operating the pump, making it easier to improve the energy efficiency of the vehicle drive system. Furthermore, by limiting the operating period of the pump, the load on the pump can be reduced, reducing the need for a highly durable pump. This makes it easier to keep the cost of the pump low while ensuring the required product life. As described above, according to this configuration, it is possible to realize a vehicle drive system that can reduce costs, ensure the required product life, and easily improve energy efficiency.

[0009] Further features and advantages of the techniques according to the present disclosure will become more apparent from the following description of exemplary and non-limiting embodiments, which proceeds with reference to the drawings. [Brief explanation of the drawings]

[0010] [Figure 1] Skeleton diagram of a vehicle drive system [Figure 2] axial partial cross-sectional view of a vehicle drive device; [Figure 3] Control Block Diagram [Figure 4] First discharge control flowchart [Figure 5] Flowchart of second discharge control [Figure 6] A time chart showing the relationship between the speed of an electric vehicle and the on / off state of a pump [Figure 7] A diagram showing the relationship between oil temperature and the oil discharge time of the pump. DETAILED DESCRIPTION OF THE INVENTION

[0011] A vehicle drive device according to the present disclosure is mounted on an electric vehicle. Hereinafter, an embodiment of the vehicle drive device will be described, taking as an example a vehicle drive device with a three-axis configuration in which components are arranged along three virtual parallel axes.

[0012] Hereinafter, the direction parallel to each of the above axes (first axis A1, second axis A2, and third axis A3) will be referred to as the "axial direction L." One side in the axial direction L will be referred to as the "axial first side L1," and the other side will be referred to as the "axial second side L2." Furthermore, the "radial direction R," "inside of the radial direction R," and "outside of the radial direction R" may be defined based on each of the above axes.

[0013] In this application, the term "driving connection" refers to a state in which two rotating elements are connected so as to be able to transmit a driving force, and includes a state in which the two rotating elements are connected so as to rotate integrally, or a state in which the two rotating elements are connected so as to be able to transmit a driving force via one or more transmission members. Such transmission members include various members that transmit rotation at the same speed or at a variable speed, such as a shaft, a gear mechanism, a belt, a chain, etc. The transmission members may also include an engagement device that selectively transmits rotation and driving force, such as a friction engagement device or a meshing engagement device.

[0014] As shown in FIGS. 1 and 2, the vehicle drive device 100 includes a rotating electric machine 1 as a driving force source for wheels W, a power transmission mechanism TM, and a case C that houses the rotating electric machine 1 and the power transmission mechanism TM.

[0015] In this embodiment, the rotating electric machine 1 is disposed on a first axis A1. The rotating electric machine 1 includes a stator 11 and a rotor 12. The stator 11 is fixed to a case C. In this embodiment, the rotor 12 is disposed radially inward of the stator 11 in the radial direction R. The rotor 12 includes a rotor core 120, a rotor shaft 121 disposed radially inward of the rotor core 120 and extending in the axial direction L, and a rotor bearing 122 that rotatably supports the rotor shaft 121 with respect to the case C. In this embodiment, the rotor bearing 122 is configured to support a portion of the rotor shaft 121 on a first axial side L1 with respect to the rotor core 120. A portion of the rotor shaft 121 on a second axial side L2 with respect to the rotor core 120 is coupled to a power transmission mechanism TM. In this embodiment, the rotor shaft 121 is drivingly coupled to an output member 8 so as to constantly rotate in conjunction with the output member 8, which is drivingly coupled to a wheel W. In this embodiment, the rotor shaft 121 is the rotating member that rotates the fastest among the rotating members that form the power transmission path from the rotating electric machine 1 to the wheels W while the electric vehicle is running.

[0016] The rotor shaft 121 is drivingly connected to the input member 9. An input gear 90 is provided on the input member 9. The input member 9 and the input gear 90 rotate in accordance with the rotation of the rotor shaft 121. In this embodiment, the input member 9 is disposed on the second axial side L2 with respect to the rotating electric machine 1. That is, the driving force generated by the rotating electric machine 1 is transmitted to the second axial side L2 with respect to the rotating electric machine 1.

[0017] The power transmission mechanism TM includes a plurality of gears that mesh with each other and is configured to transmit the driving force generated by the rotating electric machine 1 to the wheels W. The vehicle drive device 100 includes an output member 8 that is drivingly connected to the wheels W, and the power transmission mechanism TM transmits the driving force between the rotating electric machine 1 and the output member 8. In this embodiment, the power transmission mechanism TM is configured to transmit the driving force generated by the rotating electric machine 1 on a second axial side L2 of the rotating electric machine 1. In this example, the power transmission mechanism TM includes a counter gear mechanism 2 and a differential gear mechanism 3. The counter gear mechanism 2 and the differential gear mechanism 3 are arranged on the second axial side L2 of the rotating electric machine 1. The power transmission mechanism TM may include an engaging element such as a clutch or a brake.

[0018] In this embodiment, the counter gear mechanism 2 is disposed on the second axis A2. The counter gear mechanism 2 includes a first counter gear 21 and a second counter gear 22. The first counter gear 21 and the second counter gear 22 are connected to the same shaft member and disposed at different positions in the axial direction L on the shaft member. In the illustrated example, the first counter gear 21 is disposed on a first axial side L1 relative to the second counter gear 22.

[0019] In this embodiment, the first counter gear 21 is configured to have a larger diameter than the second counter gear 22. The first counter gear 21 meshes with the input gear 90. The second counter gear 22 meshes with the differential input gear 30, which will be described later.

[0020] The differential gear mechanism 3 is drivingly connected to the wheels W via an output member 8. In this embodiment, the differential gear mechanism 3 is drivingly connected to the pair of wheels W and is configured to distribute the driving force generated by the rotary electric machine 1 to the pair of wheels W. The output member 8 is drivingly connected to the wheels W, for example, via a drive shaft (not shown). The output member 8 is, for example, the same member as the gears that constitute the differential gear mechanism 3, or is a member that constitutes a connecting shaft that connects the differential gear mechanism and the drive shaft.

[0021] The differential gear mechanism 3 includes a differential input gear 30 and a plurality of bevel gears that mesh with each other. The differential input gear 30 meshes with the second counter gear 22 of the counter gear mechanism 2. The driving force input via the differential input gear 30 is distributed and transmitted to a pair of wheels W via each of a pair of output members 8.

[0022] In this embodiment, at least some of the multiple gears included in the power transmission mechanism TM are configured to scoop up the oil inside the case C. For example, the differential input gear 30 scoops up the oil inside the case C. The scooped-up oil passes through a second oil supply passage N, which will be described later, and is supplied to the rotor bearing 122.

[0023] In this way, in this embodiment, a power transmission mechanism TM having a plurality of gears that mesh with each other and that transmits the driving force generated by the rotating electric machine 1 to the wheels W; The rotor 12 includes a rotor core 120 and a rotor shaft 121. The direction in which the rotor shaft 121 extends is defined as an axial direction L, one side in the axial direction L is defined as an axial first side L1, and the other side in the axial direction L is defined as an axial second side L2. A portion of the rotor shaft 121 on the second axial side L2 relative to the rotor core 120 is connected to the power transmission mechanism TM, Rotor bearing 122 is configured to support a portion of rotor shaft 121 on first axial side L1 relative to rotor core 120.

[0024] According to this configuration, the portion of the rotor shaft 121 that is connected to the power transmission mechanism TM and the portion where the rotor bearing 122 is disposed are disposed on opposite sides of each other in the axial direction L. This allows the rotor shaft 121 to be appropriately supported by the rotor bearing 122, while the driving force of the rotating electric machine 1 that is generated as the rotor shaft 121 rotates can be appropriately output to the power transmission mechanism TM.

[0025] 2, the vehicle drive device 100 includes a pump 4 that sucks and discharges oil from a case C, and an oil supply passage P that supplies the oil discharged by the pump 4 to at least the rotor bearing 122. The pump 4 is driven by a drive source 4m that is different from the rotary electric machine 1. In this embodiment, the pump 4 is an electric pump that is driven by an electric motor that serves as the drive source 4m.

[0026] The supply oil passage P is a path through which oil flows from the pump 4 to the rotor bearing 122. Here, the supply oil passage P is referred to as the first supply oil passage P. In this embodiment, the first supply oil passage P includes a first oil passage P1, a second oil passage P2, a third oil passage P3, and a fourth oil passage P4. When the pump 4 operates, oil discharged from the pump 4 flows through the first oil passage P1, the second oil passage P2, the third oil passage P3, and the fourth oil passage P4 in this order, before reaching the rotor bearing 122. The oil that has reached the rotor bearing 122 is used to lubricate at least the rotor bearing 122.

[0027] As shown in FIG. 2, the case C covers the rotary electric machine 1 from the axial first side L1 and includes a wall Cw extending in the radial direction R (here, an end wall on the axial first side L1).

[0028] In this embodiment, the first oil passage P1 is provided in the wall portion Cw of the case C. The second oil passage P2 communicates with the first oil passage P1. In this example, the second oil passage P2 includes an opening that opens to a surface of the wall portion Cw on the second axial side L2 and an internal space of the rotor shaft 121 (intra-shaft space Si). The third oil passage P3 communicates with the second oil passage P2. In this example, the third oil passage P3 penetrates a portion of the rotor shaft 121 in the radial direction R. The fourth oil passage P4 communicates with the third oil passage P3 and also communicates with the rotor bearing 122. In this example, the fourth oil passage P4 includes an external space of the rotor shaft 121 (off-shaft space So) and a path formed along the wall portion Cw from the off-shaft space So to the rotor bearing 122.

[0029] In this embodiment, the oil discharged from the pump 4 reaches the rotor bearing 122 in the following order (1) to (5). (1) Oil discharged from the pump 4 flows through the first oil passage P1. (2) Oil flows from the first oil passage P1 to the second oil passage P2. (3) The oil in the second oil passage P2 is at least temporarily stored in the shaft space Si. (4) The oil stored in the in-shaft space Si is injected into the fourth oil passage P4 (off-shaft space So) via the third oil passage P3 by the action of centrifugal force caused by the rotation of the rotor shaft 121. (5) The oil injected into the off-axis space So flows along the wall Cw of the case C and reaches the rotor bearing 122.

[0030] It should be noted that the oil discharged from the pump 4 may reach the rotor bearing 122 regardless of the above order (1) to (5). For example, the oil stored in the in-shaft space Si may reach the rotor bearing 122 directly. In addition to the oil that branches off to flow into the second oil passage P2, the oil that flows through the first oil passage P1 may also flow directly outward in the radial direction R. Such oil is supplied to the rotating electric machine 1 from the outside in the radial direction R and is used to cool the rotating electric machine 1. After cooling the rotating electric machine 1, the oil may reach the fourth oil passage P4 and flow through the fourth oil passage P4 to reach the rotor bearing 122.

[0031] As described above, the pump 4 according to this embodiment can be used not only to cool the rotating electric machine 1 but also to lubricate the rotor bearing 122 that supports the rotor shaft 121 of the rotating electric machine 1. As described above, in this embodiment, the rotor bearing 122 is configured to support the end of the rotor shaft 121 on the first axial side L1. Therefore, oil discharged from the pump 4 is mainly supplied to the portion of the rotating electric machine 1 on the first axial side L1. On the other hand, oil is supplied to the portion of the rotating electric machine 1 on the second axial side L2, i.e., the power transmission mechanism TM, by the oil being scooped up inside the case C by rotating members (e.g., gears such as the differential input gear 30) that constitute the power transmission mechanism TM. This configuration makes it possible to limit the locations to which oil is supplied by the pump 4, thereby reducing the operating load of the pump 4. The locations to which oil is supplied by the scooped-up oil include bearings other than the rotor bearing 122 (hereinafter referred to as "target bearings"). The target bearings include, for example, bearings that rotatably support the portion of the rotor shaft 121 that is located on the second axial side L2 relative to the rotor core 120. In this embodiment, the target bearing includes a bearing that rotatably supports the output member 8 on the first axial side L1.

[0032] In this embodiment, the vehicle drive device 100 includes a second oil supply passage N that supplies oil scooped up by a gear (e.g., the differential input gear 30) included in the power transmission mechanism TM to the rotor bearing 122. In this example, the oil scooped up by the gears of the power transmission mechanism TM on the second axial side L2 relative to the rotating electric machine 1 passes outside in the radial direction R relative to the rotating electric machine 1 (see FIG. 1), reaches the first axial side L1 relative to the rotating electric machine 1, and then travels along the inner wall of the case C that faces the rotating electric machine 1 on the first axial side L1 to reach the rotor bearing 122 (see FIG. 2). The second oil supply passage N is formed along this flow of oil. The second oil supply passage N includes at least one of an opening that penetrates the case C, a closed or open path formed in the wall surface of the case C, and a path formed by a pipe that is a separate member from the case C. In addition, the second oil supply passage N may preferably include a catch tank that temporarily stores the oil scooped up by the gears of the power transmission mechanism TM.

[0033] In this way, in this embodiment, The supply oil passage P is a first supply oil passage P, At least some of the gears are configured to scoop up oil in the case C, A second oil supply passage N is provided to supply oil scooped up by the gear to the rotor bearing 122.

[0034] According to this configuration, both the oil flowing through the first oil supply passage P due to the power of the pump 4 and the oil flowing through the second oil supply passage N due to the oil being scooped up by the gears of the power transmission mechanism TM can be supplied to the rotor bearing 122. Therefore, it is easy to appropriately lubricate the rotor bearing 122.

[0035] As shown in Fig. 3, the vehicle drive device 100 includes a control device 5 that controls the pump 4. The control device 5 includes an arithmetic processing device such as a CPU (Central Processing Unit), as well as a storage device that can be accessed by the arithmetic processing device, such as a RAM (Random Access Memory) or a ROM (Read Only Memory). Each function of the control device 5 (the function of each functional unit described below) is realized by software (programs) stored in the storage device, or hardware such as a separately provided arithmetic circuit, or both. The arithmetic processing device included in the control device 5 operates as a computer that executes each program.

[0036] An electric vehicle is equipped with various sensors, and the control device 5 is configured to be able to acquire information detected by the various sensors. Functional units (see FIG. 3) provided in the control device 5 for acquiring various information acquire necessary information based on the information detected by the sensors. Note that the multiple functional units (51 to 55) included in the control device 5 are at least conceptually distinct as shown in FIG. 3, and do not necessarily need to be physically distinct. Furthermore, the multiple functional units included in the control device 5 do not need to be realized by common hardware, and may be realized by multiple pieces of hardware that can communicate with each other.

[0037] The control device 5 controls the operation of the pump 4 by controlling the driving of the drive source 4m. The control device 5 includes a power supply state acquisition unit 51 that acquires information indicating the on / off state of the main power supply (e.g., a main switch or an ignition switch) of the electric vehicle, and a vehicle speed acquisition unit 52 that acquires information indicating the vehicle speed of the electric vehicle. The vehicle speed acquisition unit 52 may be configured to acquire information regarding the vehicle speed itself, or may be configured to acquire information regarding an index that changes depending on the vehicle speed (e.g., the rotational speed of the output member 8 or a member that rotates integrally with the output member 8).

[0038] In this embodiment, the control device 5 further includes a travel distance acquisition unit 53 that acquires information indicating the travel distance of the electric vehicle, and an elapsed time acquisition unit 54 that acquires information indicating the elapsed time. The elapsed time acquisition unit 54 is a functional unit that acquires information regarding the time that has elapsed since the occurrence or end of a certain event, and in this example, as will be described later, is configured to acquire information regarding the time that has elapsed since the pump 4 stopped operating. In addition, in this embodiment, the control device 5 further includes an oil temperature acquisition unit 55 that acquires information indicating the temperature of the oil in the case C.

[0039] The control device 5 is configured to be able to execute a first discharge control and a second discharge control. The first discharge control is executed on the condition that a first discharge condition is satisfied. The second discharge control is executed on the condition that a second discharge condition is satisfied. Here, "executed as a condition" includes both a configuration in which the control is executed when the condition is satisfied and a configuration in which the control is executed when other conditions are satisfied in addition to the first condition.

[0040] The first discharge control will be described with reference to FIG.

[0041] The first discharge condition for performing the first discharge control is that the main power supply is turned from off to on, and that the vehicle speed is equal to or greater than a predetermined vehicle speed threshold Vx.

[0042] 4, the control device 5 determines whether the main power supply has been switched from off to on (step #11). This determination is made based on the information obtained by the power supply state obtaining unit 51.

[0043] When the control device 5 determines that the main power supply has changed from off to on (step #11: Yes), it determines whether the vehicle speed of the electric vehicle has reached the vehicle speed threshold Vx (step #12). This determination is made based on the information acquired by the vehicle speed acquisition unit 52. The vehicle speed threshold Vx is set based on the vehicle speed corresponding to the rotational speed of the rotor bearing 122. The vehicle speed threshold Vx is a value that is set in advance through experiments, etc. For example, the vehicle speed threshold Vx may be set to a value (speed) at which it can be determined that the electric vehicle has accelerated from a stopped state or a creeping state due to manual accelerator operation, etc. Specifically, the vehicle speed threshold Vx is set in the range of 10 kilometers per hour to 20 kilometers per hour. Preferably, the vehicle speed threshold Vx is set to 15 kilometers per hour. However, the vehicle speed threshold Vx may vary depending on the performance of each component of the vehicle drive device 100, the performance of the oil, the environment in which the electric vehicle is used, etc.

[0044] When the control device 5 determines that the vehicle speed of the electric vehicle has reached the vehicle speed threshold Vx (step #12: Yes), the control device 5 executes the first discharge control (step #13).

[0045] In the first discharge control, the control device 5 operates the pump 4 for a predetermined first discharge time T1 (see also FIG. 6). Note that FIG. 4 assumes that the first discharge control is executed when the first discharge condition is satisfied, but in this embodiment, as will be described later, operation of the pump 4 is prohibited when the oil temperature is below the oil temperature threshold Ox. Therefore, in this embodiment, the first discharge control is executed when the first discharge condition is satisfied and also when the condition that the oil temperature is equal to or higher than the oil temperature threshold Ox is satisfied.

[0046] Next, the second discharge control will be described with reference to FIG.

[0047] The second discharge condition for performing the second discharge control is at least one of the following: the travel distance after the previous operation of the pump 4 is equal to or greater than a predetermined distance threshold; and the elapsed time is equal to or greater than a predetermined time threshold Tx. That is, the second discharge control is performed when at least one of these conditions is satisfied. Note that the "previous operation of the pump 4" does not include the operation of the pump 4 before the main power is turned on. In this example, the second discharge condition is that the elapsed time (the time elapsed since the operation of the pump 4 was stopped) is equal to or greater than a predetermined time threshold Tx.

[0048] As shown in FIG. 5, after the previous operation of the pump 4 is completed (step #21), the control device 5 determines whether the travel distance since the end of the pump 4 operation is equal to or greater than a predetermined distance threshold, or whether the elapsed time since the end of the pump 4 operation is equal to or greater than a time threshold Tx (step #22). In this example, the control device 5 determines whether the elapsed time since the end of the pump 4 operation is equal to or greater than the time threshold Tx. This determination is made based on the information acquired by the elapsed time acquisition unit 54. The time threshold Tx is a value that is set in advance through experiments or the like. The time threshold Tx is set to a value (time) that will not cause any problems for the rotor bearing 122 to be lubricated even if oil is not supplied from the pump 4. For example, the time threshold Tx is set in the range of 8 to 12 hours. Preferably, the time threshold Tx is set to 10 hours. However, the time threshold Tx may vary depending on the performance of each component of the vehicle drive device 100, the performance of the oil, the environment in which the electric vehicle is used, or the like.

[0049] When the control device 5 determines that the time elapsed since the operation of the pump 4 ended is equal to or greater than the time threshold value Tx (step #22: Yes), the control device 5 executes the second discharge control (step #23).

[0050] In the second discharge control, the control device 5 operates the pump 4 for a predetermined second discharge time T2 (see also FIG. 6). Note that FIG. 5 assumes that the second discharge control is executed when the second discharge condition is satisfied, but in this embodiment, as will be described later, the operation of the pump 4 is prohibited when the oil temperature is below the oil temperature threshold Ox. Therefore, in this embodiment, the second discharge control is executed when the second discharge condition is satisfied and the oil temperature is equal to or higher than the oil temperature threshold Ox.

[0051] The second discharge control is repeatedly executed while the second discharge condition is satisfied from when the main power supply is turned on to when it is turned off. In other words, the first discharge of oil after the main power supply is turned on is executed by the first discharge control, and the second and subsequent discharges of oil are executed by the second discharge control.

[0052] As described above, the vehicle drive device 100 a rotating electric machine 1 having a rotor 12 as a driving force source for a wheel W; a case C that accommodates the rotating electrical machine 1 and oil; a pump 4 driven by a drive source 4m different from the rotating electric machine 1, which sucks and discharges oil from the case C; an oil supply passage P for supplying oil discharged by the pump 4 to at least a rotor bearing 122 that rotatably supports the rotor 12; a control device 5 for controlling the pump 4; Equipped with The control device 5 includes a power supply state acquisition unit 51 that acquires information indicating an on / off state of a main power supply (not shown) of the electric vehicle, and a vehicle speed acquisition unit 52 that acquires information indicating the vehicle speed of the electric vehicle, The control device 5 executes a first discharge control to operate the pump 4 for a predetermined first discharge time T1, on the condition that the main power supply has been turned on from off and the vehicle speed has become equal to or greater than a predetermined vehicle speed threshold Vx.

[0053] According to this configuration, the conditions for operating the pump 4 through the first discharge control include not only that the main power supply is switched from off to on, but also that the vehicle speed is equal to or greater than the vehicle speed threshold Vx. In other words, the pump 4 does not necessarily operate when the power supply is turned on, but only operates when the vehicle speed reaches a certain high level. Therefore, the operating time of the pump 4 can be reduced. This reduces energy consumption due to the operation of the pump 4, making it easier to improve the energy efficiency of the vehicle drive system 100. Furthermore, by limiting the operating period of the pump 4, the load on the pump 4 can be reduced, thereby reducing the need for a highly durable pump. This makes it easier to keep the cost of the pump 4 low while ensuring the required product life. As described above, according to this configuration, it is possible to realize a vehicle drive system 100 that can ensure the required product life while keeping costs down and that easily improves energy efficiency.

[0054] In addition, in this embodiment, The control device 5 further includes a travel distance acquisition unit 53 that acquires information indicating a travel distance of the electric vehicle, and an elapsed time acquisition unit 54 that acquires information indicating an elapsed time, The control device 5 executes a second discharge control to operate the pump 4 for a predetermined second discharge time T2 under at least one of the conditions that the travel distance after the previous operation of the pump 4 has ended is equal to or greater than a predetermined distance threshold, and that the elapsed time is equal to or greater than a predetermined time threshold Tx.

[0055] According to this configuration, after the electric vehicle starts to run, oil discharged by the pump 4 can be periodically supplied to the rotor bearing 122. Therefore, the rotor bearing 122 can be appropriately lubricated even after the electric vehicle has started to run. Furthermore, according to this configuration, the pump 4 is not operated all the time, but is operated only for a predetermined time when certain conditions are met, so that the operating time of the pump 4 can be kept short.

[0056] FIG. 6 is a time chart showing the relationship between the vehicle speed of the electric vehicle and the on / off state of the pump.

[0057] 6, when the electric vehicle is stopped, the main power supply is switched from off to on, and the vehicle speed increases from zero. When the vehicle speed of the electric vehicle becomes equal to or greater than the vehicle speed threshold Vx, the control device 5 executes the first discharge control and operates the pump 4 for the first discharge time T1.

[0058] Then, after operating the pump 4 for the first discharge time T1, the control device 5 stops the pump 4. When the time that has elapsed since the pump 4 stopped operating becomes equal to or greater than the time threshold Tx, the control device 5 executes the second discharge control, operates the pump 4 again, and continues this operation for the second discharge time T2.

[0059] In this embodiment, the first discharge time T1 is set based on the time it takes for oil discharged from the pump 4 to reach the rotor bearing 122 via the first oil supply passage P. In this example, the first discharge time T1 is set longer than the second discharge time T2. During the first discharge control, in which oil is discharged from the pump 4 only after the main power supply of the electric vehicle is turned on, the oil temperature is often lower than when the electric vehicle is running, and the viscosity of oil increases when the temperature is lower. Therefore, by setting the first discharge time T1, i.e., the operating time of the pump 4 during the first discharge control, longer than the second discharge time T2, it is easier for the oil to reach the rotor bearing 122 appropriately, even when the viscosity of the oil is somewhat high.

[0060] On the other hand, in the second discharge control performed after the discharge of oil by the first discharge control, the vehicle drive device 100 is already operating, so the oil temperature is likely to be higher than when the main power is switched on. In this case, the viscosity of the oil is relatively low, so the oil is more likely to reach the rotor bearing 122 than when the first discharge control is performed. Therefore, the second discharge time T2 is set shorter than the first discharge time T1. This makes it possible to reduce the operating time of the pump 4. Therefore, it is possible to reduce energy consumption by operating the pump 4, thereby improving the energy efficiency of the vehicle drive device 100, and it is possible to reduce the load on the pump 4, thereby ensuring a long product life.

[0061] As described above, in this embodiment, The vehicle speed threshold Vx is set based on the vehicle speed corresponding to the rotation speed of the rotor bearing 122, The first discharge time T1 is set based on the time it takes for the oil discharged from the pump 4 to reach the rotor bearing 122 via the supply oil passage P.

[0062] According to this configuration, under necessary conditions, oil can be appropriately supplied to the rotor bearing 122. Therefore, insufficient lubrication of the rotor bearing 122 can be avoided.

[0063] FIG. 7 shows the relationship between the oil temperature and the time it takes for the pump to discharge the oil.

[0064] As described above, the lower the temperature of the oil, the higher the viscosity, and the longer it takes for the oil to reach the rotor bearing 122 from the pump 4. Furthermore, if the temperature of the oil is too low, the viscosity of the oil becomes extremely high. In this case, the load on the pump 4 becomes excessive, which shortens the life of the pump 4.

[0065] Therefore, in this embodiment, The control device 5 further includes an oil temperature acquisition unit 55 that acquires information indicating the temperature of the oil in the case C (see FIG. 3 ). The control device 5 is When the oil temperature is equal to or higher than a predetermined oil temperature threshold Ox, the first discharge time T1 is set to be longer as the oil temperature decreases, If the oil temperature is below the oil temperature threshold Ox, the operation of the pump 4 is prohibited.

[0066] The oil temperature threshold Ox is determined based on the viscosity of the oil. That is, the oil temperature threshold Ox is set to a temperature at which the viscosity of the oil reaches a value that may lead to failure of the pump 4. Although it depends on the performance of the oil, in the case of common oils used in vehicle drive systems (e.g., ATF (Automatic Transmission Fluid)), the oil temperature threshold Ox is set in the range of minus 20 degrees to minus 30 degrees. For example, the oil temperature threshold Ox may be set to minus 25 degrees.

[0067] As described above, generally, oil viscosity increases as oil temperature decreases, and as the viscosity increases, oil becomes more difficult to flow through the oil passage. Therefore, as the oil temperature decreases, it takes longer for oil discharged from the pump 4 to reach the rotor bearing 122. According to this configuration, the first discharge time T1 is set longer as the oil temperature decreases, allowing even low-temperature, high-viscosity oil to reach the rotor bearing 122 appropriately. On the other hand, oil that is too low in temperature and therefore has a significantly high viscosity can place an excessive load on the pump 4 that discharges it, which can shorten the life of the pump 4. According to this configuration, when the oil temperature is below the oil temperature threshold Ox, operation of the pump 4 is prohibited, thereby avoiding such adverse effects. Note that FIG. 7 illustrates an example in which the first discharge time T1 is set continuously longer as the oil temperature decreases. However, the first discharge time T1 may also be set to be gradually longer as the oil temperature decreases.

[0068] Other Embodiments Next, other embodiments will be described.

[0069] (1) In the above embodiment, an example has been described in which the second discharge time T2 is set shorter than the first discharge time T1. However, without being limited to this example, the second discharge time T2 may be set longer than the first discharge time T1 or may be set the same as the first discharge time T1. Furthermore, similar to the first discharge time T1, when the oil temperature is equal to or higher than a predetermined oil temperature threshold Ox, the second discharge time T2 may be set longer as the oil temperature decreases.

[0070] (2) In the above embodiment, the control device 5 executes the first discharge control to lubricate the rotor bearing 122 when the first discharge condition is satisfied, and executes the second discharge control when the second discharge condition is satisfied. However, the control device 5 may also operate the pump 4 when a condition different from the above conditions is satisfied. For example, the control device 5 may operate the pump 4 when a rotating electric machine cooling condition, which is a condition for cooling the rotating electric machine 1, is satisfied. In this case, the vehicle drive device 100 may include a sensor that detects the temperature of the rotating electric machine 1. For example, when the temperature of the rotating electric machine 1 is equal to or higher than a predetermined temperature threshold, it is determined that the rotating electric machine cooling condition is satisfied. For example, the control device 5 executes the third discharge control, which operates the pump 4 for a predetermined third discharge time, when the rotating electric machine cooling condition is satisfied.

[0071] (3) In the above embodiment, an example was described in which the second discharge condition is that the elapsed time (the time elapsed since the operation of the pump 4 ended) is equal to or greater than a predetermined time threshold Tx. However, without being limited to this example, the second discharge condition may be that the traveled distance after the previous operation of the pump 4 ended is equal to or greater than a predetermined distance threshold. Alternatively, the second discharge condition may be that both the elapsed time is equal to or greater than the time threshold Tx and the traveled distance is equal to or greater than a distance threshold are satisfied.

[0072] (4) In the above embodiment, a three-axis vehicle drive device 100 is illustrated. However, the invention is not limited to this example, and the vehicle drive device 100 may have a single-axis configuration in which the components are arranged coaxially. Furthermore, the power transmission mechanism TM may include a planetary gear reduction mechanism.

[0073] (5) The configurations disclosed in the above-described embodiments can be applied in combination with configurations disclosed in other embodiments, as long as no contradictions arise. Regarding other configurations, the embodiments disclosed in this specification are merely examples in all respects. Therefore, various modifications can be made as appropriate within the scope of the present disclosure.

[0074] [Summary of this embodiment] The above-described embodiments of the vehicle drive device will be summarized below.

[0075] A vehicle drive device (100) mounted on an electric vehicle, a rotating electric machine (1) having a rotor (12) as a driving force source for a wheel (W); a case (C) for accommodating a rotating electrical machine (1) and oil; a pump (4) driven by a drive source (4m) different from the rotating electric machine (1) and configured to suck and discharge oil from the case (C); an oil supply passage (P) for supplying oil discharged by the pump (4) to at least a rotor bearing (122) that rotatably supports the rotor (12); a control device (5) for controlling the pump (4); Equipped with The control device (5) includes a power supply state acquisition unit (51) that acquires information indicating an on / off state of a main power supply of the electric vehicle, and a vehicle speed acquisition unit (52) that acquires information indicating a vehicle speed of the electric vehicle, The control device (5) executes a first discharge control to operate the pump (4) for a predetermined first discharge time (T1) on the condition that the main power supply has been turned on from off and the vehicle speed has become equal to or greater than a predetermined vehicle speed threshold (Vx).

[0076] According to this configuration, the conditions for operating the pump (4) through the first discharge control include not only the main power supply being switched from off to on but also the vehicle speed being equal to or greater than the vehicle speed threshold (Vx). That is, the pump (4) does not necessarily operate when the power supply is turned on, but only operates when the vehicle speed reaches a certain high level. Therefore, the operating time of the pump (4) can be reduced. This reduces energy consumption due to the operation of the pump (4), making it easy to improve the energy efficiency of the vehicle drive device (100). Furthermore, limiting the operating period of the pump (4) reduces the load on the pump (4), thereby reducing the need for a highly durable pump. This makes it easy to reduce the cost of the pump (4) while ensuring the required product life. As described above, according to this configuration, it is possible to realize a vehicle drive device (100) that can reduce costs, ensure the required product life, and easily improve energy efficiency.

[0077] The control device (5) further includes a travel distance acquisition unit (53) that acquires information indicating a travel distance of the electric vehicle, and an elapsed time acquisition unit (54) that acquires information indicating an elapsed time, It is preferable that the control device (5) executes second discharge control to operate the pump (4) for a predetermined second discharge time (T2) under at least one of the conditions that the travel distance after the previous operation of the pump (4) has become equal to or greater than a predetermined distance threshold and that the elapsed time has become equal to or greater than a predetermined time threshold (Tx) after the previous operation of the pump (4) has ended.

[0078] According to this configuration, after the electric vehicle starts to travel, oil discharged by the pump (4) can be periodically supplied to the rotor bearing (122). Therefore, the rotor bearing (122) can be appropriately lubricated even after the electric vehicle has started to travel. Furthermore, according to this configuration, the pump (4) is not operated all the time, but is operated only for a predetermined time when certain conditions are satisfied, thereby reducing the operating time of the pump (4).

[0079] The control device (5) further includes an oil temperature acquisition unit (55) that acquires information indicating the temperature of oil in the case (C), The control device (5) When the oil temperature is equal to or higher than a predetermined oil temperature threshold value (Ox), the first discharge time (T1) is set longer as the oil temperature decreases, Preferably, operation of the pump (4) is inhibited if the oil temperature is below an oil temperature threshold (Ox).

[0080] As described above, generally, as the oil temperature decreases, the viscosity of the oil increases, and as the viscosity increases, the oil becomes more difficult to flow through the oil passages. Therefore, as the oil temperature decreases, the time it takes for the oil discharged from the pump (4) to reach the rotor bearing (122) increases. According to this configuration, the first discharge time (T1) is set to be longer as the oil temperature decreases, so that even low-temperature, high-viscosity oil can reach the rotor bearing (122) appropriately. On the other hand, oil that is extremely viscous due to too low a temperature can impose an excessive load on the pump (4) that discharges the oil, which can easily shorten the life of the pump (4). According to this configuration, when the oil temperature is below the oil temperature threshold (Ox), the operation of the pump (4) is prohibited, thereby avoiding such a problem.

[0081] The vehicle speed threshold (Vx) is set based on a vehicle speed corresponding to the rotational speed of the rotor bearing (122), The first discharge time (T1) is preferably set based on the time it takes for oil discharged from the pump (4) to reach the rotor bearing (122) through the oil supply passage (P).

[0082] According to this configuration, oil can be appropriately supplied to the rotor bearing (122) under necessary conditions, thereby preventing the rotor bearing (122) from being insufficiently lubricated.

[0083] a power transmission mechanism (TM) having a plurality of gears that mesh with each other and that transmits the driving force generated by the rotating electric machine (1) to wheels (W); The rotor (12) includes a rotor core (120) and a rotor shaft (121). The direction in which the rotor shaft (121) extends is defined as the axial direction (L), one side in the axial direction (L) is defined as the first axial side (L1), and the other side in the axial direction (L) is defined as the second axial side (L2), a portion of the rotor shaft (121) on a second axial side (L2) relative to the rotor core (120) is connected to a power transmission mechanism (TM); Preferably, the rotor bearing (122) is configured to support a portion of the rotor shaft (121) on the first axial side (L1) with respect to the rotor core (120).

[0084] According to this configuration, the portion of the rotor shaft (121) that is connected to the power transmission mechanism (TM) and the portion where the rotor bearing (122) is disposed are located on opposite sides of each other in the axial direction (L). This allows the rotor shaft (121) to be appropriately supported by the rotor bearing (122), and allows the driving force of the rotating electric machine (1) that is generated as the rotor shaft (121) rotates to be appropriately output to the power transmission mechanism (TM).

[0085] The oil supply passage (P) is a first oil supply passage (P), At least some of the gears are configured to scoop up oil in the case (C), It is preferable to provide a second oil supply passage (N) for supplying oil scooped up by the gear to the rotor bearing (122).

[0086] According to this configuration, both the oil flowing through the first oil supply passage (P) due to the power of the pump (4) and the oil flowing through the second oil supply passage (N) due to the oil being scooped up by the gears of the power transmission mechanism (TM) can be supplied to the rotor bearing (122), thereby facilitating appropriate lubrication of the rotor bearing (122). [Industrial Applicability]

[0087] The technology according to the present disclosure can be used in a vehicle drive device mounted on an electric vehicle. [Explanation of symbols]

[0088] 100: vehicle drive device, 1: rotating electric machine, 12: rotor, 120: rotor core, 121: rotor shaft, 122: rotor bearing, 4: pump, 4m: drive source, 5: control device, 51: power supply status acquisition unit, 52: vehicle speed acquisition unit, 53: mileage acquisition unit, 54: elapsed time acquisition unit, 55: oil temperature acquisition unit, C: case, P: first supply oil passage (supply oil passage), N: second supply oil passage, TM: power transmission mechanism, W: wheel, T1: first discharge time, T2: second discharge time, Tx: time threshold, Vx: vehicle speed threshold, Ox: oil temperature threshold, W: wheel, L: axial direction, L1: first axial side, L2: second axial side

Claims

1. A vehicle drive device mounted on an electric vehicle, a rotating electric machine having a rotor as a driving force source for the wheels; a case that accommodates the rotating electrical machine and oil; a pump driven by a drive source different from the rotary electric machine, which sucks and discharges oil from inside the case; an oil supply passage that supplies the oil discharged by the pump to at least a rotor bearing that rotatably supports the rotor; a control device for controlling the pump; Equipped with the control device includes a power supply state acquisition unit that acquires information indicating an on / off state of a main power supply of the electric vehicle, and a vehicle speed acquisition unit that acquires information indicating a vehicle speed of the electric vehicle; The control device executes first discharge control to operate the pump for a predetermined first discharge time, on the condition that the main power supply has been turned on from off and the vehicle speed has become equal to or greater than a predetermined vehicle speed threshold.

2. the control device further includes a travel distance acquisition unit that acquires information indicating a travel distance of the electric vehicle, and an elapsed time acquisition unit that acquires information indicating an elapsed time, 2. The vehicle drive device according to claim 1, wherein the control device executes second discharge control to operate the pump for a predetermined second discharge time on at least one of the conditions that the traveling distance after the previous operation of the pump has become equal to or greater than a predetermined distance threshold and that the elapsed time has become equal to or greater than a predetermined time threshold.

3. The control device further includes an oil temperature acquisition unit that acquires information indicating the temperature of the oil in the case, The control device When the oil temperature is equal to or higher than a predetermined oil temperature threshold, the first discharge time is set to be longer as the oil temperature decreases; 2. The vehicle drive system according to claim 1, wherein operation of the pump is inhibited when the oil temperature is lower than the oil temperature threshold value.

4. the vehicle speed threshold is set based on the vehicle speed corresponding to the rotational speed of the rotor bearing; 2. The vehicle drive device according to claim 1, wherein the first discharge time is set based on a time required for oil discharged from the pump to reach the rotor bearing via the oil supply passage.

5. a power transmission mechanism including a plurality of gears that mesh with each other and that transmits driving force generated by the rotating electric machine to the wheels; the rotor includes a rotor core and a rotor shaft, The direction in which the rotor shaft extends is defined as an axial direction, one side in the axial direction is defined as an axial first side, and the other side in the axial direction is defined as an axial second side, a portion of the rotor shaft on the second axial side with respect to the rotor core is connected to the power transmission mechanism; The vehicle drive device according to claim 1 , wherein the rotor bearing is configured to support a portion of the rotor shaft on the first axial side with respect to the rotor core.

6. the oil supply passage is a first oil supply passage, At least some of the gears are configured to scoop up oil in the case, The vehicle drive device according to claim 5 , further comprising a second oil supply passage that supplies oil scooped up by the gear to the rotor bearing.

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