Electric vehicles

Abstract

To provide an electric vehicle that can suppress the deterioration of the durability of parts that require lubrication. [Solution] When the electric vehicle is not in a state requiring electric drive, the motor is stopped and the disconnect mechanism is disconnected. On the other hand, when the electric vehicle is not in a state requiring electric drive, and the state approaches a state requiring electric drive, the disconnect mechanism is disconnected while the motor is driven and lubrication is performed. This prevents or suppresses the situation in which parts requiring lubrication are poorly lubricated when the electric vehicle is in a state requiring electric drive and power from the motor is transmitted to the planetary gear system. Therefore, a decrease in the durability of parts requiring lubrication can be suppressed.

Description

Technical Field

[0001] The present invention relates to an electric vehicle having a lubrication oil passage provided in a pinion shaft of a planetary gear device that transmits power from an electric motor to drive wheels.

Background Art

[0002] A drive unit having an electric motor, a planetary gear device that transmits power from the electric motor to drive wheels, an electric oil pump that discharges the sucked oil, and a lubrication oil passage is well known. For example, the vehicle drive device described in Patent Document 1 is such a device. In this Patent Document 1, as a lubrication oil passage, a lubrication oil passage provided in a pinion shaft of a planetary gear device is illustrated. The lubrication oil passage includes an axial oil passage extending in the axial direction of the pinion shaft and a radial oil passage connected to the axial oil passage and extending in the radial direction of the pinion shaft. The oil discharged from the electric oil pump is introduced into the axial oil passage, and the oil introduced into the axial oil passage is supplied to components that require lubrication via the radial oil passage. Components that require lubrication are, for example, needle bearings disposed between a pinion shaft and a pinion rotatably supported about an axis by the pinion shaft. Patent Document 1 discloses that the vehicle drive device may be mounted on a hybrid vehicle, that is, an electric vehicle, and that the electric vehicle may include a controller, that is, a control device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Incidentally, it is conceivable to provide a disconnect mechanism that disconnects the power transmission path between the planetary gear system and the drive wheels. When the electric vehicle is not running in a state where the electric motor is required to drive, the electric motor is stopped, and the disconnect mechanism is set to a disconnected state that cuts the power transmission path. In this state, the pinion shaft is not driven to rotate, and centrifugal force no longer acts on the lubrication oil passage. In this state, oil does not reach the parts that require lubrication, and those parts are in a state of insufficient lubrication, or poor lubrication. When the electric vehicle is running in a state where the electric motor is required to drive, and power from the electric motor is transmitted to the planetary gear system, loads are applied to the parts that require lubrication while they are still in a poor lubrication state, which may lead to a decrease in the durability of those parts.

[0005] This invention was made against the above circumstances, and its objective is to provide an electric vehicle that can suppress the deterioration of the durability of parts that require lubrication. [Means for solving the problem]

[0006] The gist of the first invention is an electric vehicle comprising: (a) a drive unit having an electric motor, a planetary gear system for transmitting power from the electric motor to the drive wheels, an electric oil pump for discharging inhaled oil, a lubrication oil passage provided on the pinion shaft of the planetary gear system, and a component requiring lubrication to which the oil is supplied via the lubrication oil passage; and a control device, wherein (b) the drive unit further comprises a disconnect mechanism provided in the power transmission path between the planetary gear system and the drive wheels for disconnecting the power transmission path; (c) the lubrication oil passage includes an axial oil passage extending in the axial direction of the pinion shaft to which the oil discharged from the electric oil pump is introduced, and a radial oil passage connected to the axial oil passage and extending radially of the pinion shaft through which the oil led out from the axial oil passage and supplied to the component flows; and (d) the control device controls the electric drive requirement state when the running state of the electric vehicle is such that the electric motor is required to be driven. (e) If the control device determines that the driving state is the state requiring electric drive, it drives the electric motor and sets the disconnect mechanism to the connected state in which the power transmission path is connected, and performs a lubrication operation to lubricate the parts by controlling the drive of the electric oil pump and rotating the pinion shaft; (f) If the control device determines that the driving state is not the state requiring electric drive, it stops the drive of the electric motor and sets the disconnect mechanism to the disconnected state in which the power transmission path is disconnected; (g) When the control device determines that the driving state is not the state requiring electric drive, it determines whether the driving state is approaching the state requiring electric drive; (h) If the control device determines that the driving state is approaching the state requiring electric drive, it drives the electric motor and performs the lubrication operation while setting the disconnect mechanism to the disconnected state. [Effects of the Invention]

[0007] According to the first invention, when the electric vehicle is not in a state requiring electric drive, the electric motor is stopped and the disconnect mechanism is disconnected. On the other hand, when the electric vehicle is not in a state requiring electric drive, and the state approaches a state requiring electric drive, the disconnect mechanism is disconnected while the electric motor is driven and lubrication is performed. This prevents or suppresses the situation in which parts requiring lubrication are poorly lubricated when the electric vehicle is in a state requiring electric drive and power from the electric motor is transmitted to the planetary gear system. Therefore, a decrease in the durability of parts requiring lubrication can be suppressed. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram illustrates the schematic configuration of an electric vehicle to which the present invention is applied, as well as the main components of the control system for various types of control in the electric vehicle. [Figure 2] This is a cross-sectional view showing an enlarged portion of the main part of the front drive unit in Figure 1. [Figure 3] This flowchart explains the key aspects of the control operation of an electronic control unit, and specifically describes the control operation to suppress the deterioration of the durability of parts that require lubrication. This flowchart shows an embodiment that determines whether or not the vehicle is approaching a state where front-wheel drive is required due to high vehicle speed. [Figure 4] This flowchart illustrates the essential parts of the control operation of an electronic control device, and is a flowchart illustrating the control operation to suppress the decrease in durability of parts that require lubrication, and is a different embodiment from the flowchart in Figure 3. (a) shows an embodiment in which it is determined whether or not the vehicle is approaching a state requiring front drive based on low vehicle speed. (b) shows an embodiment in which it is determined whether or not the vehicle is approaching a state requiring front drive based on the amount of drive required. (c) shows an embodiment in which it is determined whether or not the vehicle is approaching a state requiring front drive based on uphill driving. [Figure 5]This flowchart illustrates the key aspects of the control operation of an electronic control unit, and specifically describes the control operation for properly performing pre-lubrication control even at low oil temperatures. (a) shows an embodiment for setting a predetermined engagement preparation amount. (b) shows an embodiment for setting the output of the electric oil pump. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. [Examples]

[0010] Figure 1 is a diagram illustrating the schematic configuration of an electric vehicle 10 to which the present invention is applied, and also illustrates the main parts of the control system for various controls in the electric vehicle 10. In Figure 1, the electric vehicle 10 is equipped with a front wheel 12, a front drive unit 20 that drives the front wheel 12, a rear wheel 14, and a rear drive unit 30 that drives the rear wheel 14, all spaced apart from each other. The electric vehicle 10 is also equipped with a battery 40, which is a rechargeable DC power source. Both the front wheel 12 and the rear wheel 14 are drive wheels.

[0011] The front drive unit 20 comprises a front case 22, a front power transmission unit 50, a front electric motor MGF, and a front power control unit PCUF. The front case 22 is a case that is mounted on the vehicle body.

[0012] The front electric motor MGF is housed in the front case 22. The front electric motor MGF is a known rotating electric machine, a so-called motor generator, and is connected to the battery 40 via a front power control unit PCUF. The front power control unit PCUF includes, for example, an inverter, and controls the power exchanged between the battery 40 and the front electric motor MGF. The front power control unit PCUF controls the front electric motor torque Tmgf, which is the torque of the front electric motor MGF, by being controlled by an electronic control unit 70, which will be described later.

[0013] The front power transmission device 50 includes a front planetary gear unit 52, a front differential gear 54, etc., within the front case 22. The front power transmission device 50 also includes a pair of front drive shafts 56 connected to the front differential gear 54. The front planetary gear unit 52 has its input side connected to the front electric motor MGF so as to transmit power, and its output side connected to the front differential gear 54 so as to transmit power. The front drive shafts 56 connect the front differential gear 54 to the front wheels 12. The front power transmission device 50 transmits power from the front electric motor MGF to the front wheels 12.

[0014] The rear drive system 30 comprises a rear case 32, a rear power transmission system 60, a rear electric motor MGR, and a rear power control device PCUR. The rear case 32 is a case that is mounted on the vehicle body.

[0015] The rear electric motor MGR is located inside the rear case 32. The rear electric motor MGR is a known rotating electric machine, a so-called motor generator, and is connected to the battery 40 via the rear power control device PCUR. The rear power control device PCUR has the same functions as the front power control device PCUF and controls the rear electric motor torque Tmgr, which is the torque of the rear electric motor MGR, by being controlled by the electronic control device 70 described later.

[0016] The rear power transmission system 60, like the front power transmission system 50, includes a rear planetary gear system 62, a rear differential gear 64, a pair of rear drive shafts 66, and the like. The rear power transmission system 60 transmits power from the rear electric motor MGR to the rear wheels 14.

[0017] The front power transmission device 50 includes a dog clutch 58 and an actuator ACT. The dog clutch 58 is a known meshing clutch provided in the power transmission path between the front planetary gear device 52 and the front wheels 12. The actuator ACT is controlled by an electronic control device 70 described later to control the switching between the engaged state and the released state of the dog clutch 58.

[0018] The electric vehicle 10 is an all-wheel drive vehicle capable of adjusting the drive torque distribution between the front wheels 12 and the rear wheels 14. All-wheel drive (AWD) and four-wheel drive (4WD) are synonymous. In addition to traveling in 4WD control (4WD state is also synonymous), the electric vehicle 10 can also travel in two-wheel drive (2WD) control (2WD state is also synonymous) that distributes drive torque only to the rear wheels 14. The 4WD state is a driving state in which the front wheels 12 and the rear wheels 14 are driven in the engaged state of the dog clutch 58, and the power transmission path between the front wheels 12 and the front electric motor MGF is in a connected state. The 2WD state is a driving state in which only the rear wheels 14 are driven in the released state of the dog clutch 58, and the power transmission path between the front wheels 12 and the front electric motor MGF is in a disconnected state. By disconnecting the power transmission path during 2WD control, it is possible to avoid the front planetary gear device 52, the front electric motor MGF, etc. from being rotated by the front wheels 12. Thereby, during 2WD control, the loss due to rotation from the front wheel 12 side is suppressed, and the electricity cost is improved. The dog clutch 58 is a disconnect mechanism of the present invention that disconnects and connects the power transmission path between the front planetary gear device 52 and the front wheels 12. Incidentally, when not particularly distinguished, the 4WD state of the electric vehicle 10 and the engaged state of the dog clutch 58 are synonymous, and the 2WD state of the electric vehicle 10 and the released state of the dog clutch 58 are synonymous.

[0019] FIG. 2 is a cross-sectional view showing a partially enlarged main part of the front drive device 20.

[0020] In FIG. 2, the front electric motor MGF is arranged to be rotatable around the rotation axis center CL. The front electric motor MGF includes a stator MGFs fixedly fixed to the front case 22, a rotor MGFr arranged on the inner peripheral side of the stator MGFs, and a rotor shaft RS integrally connected to the inner peripheral surface of the rotor MGFr. The front differential gear 54 and the front drive shaft 56 are arranged to be rotatable around the rotation axis center CL.

[0021] The front planetary gear device 52 is arranged to be rotatable around the rotation axis center CL. The front planetary gear device 52 includes a sun gear S, a stepped pinion set SP, a carrier CA, and a ring gear R. The sun gear S is connected to the rotor shaft RS so as not to rotate relative to each other and is provided to be rotatable around the rotation axis center CL. The carrier CA is provided to be rotatable around the rotation axis center CL and supports the stepped pinion set SP so as to be revolvable around the rotation axis center CL.

[0022] The stepped pinion set SP includes a pinion shaft PS, a large-diameter pinion P1, a small-diameter pinion P2, and a needle bearing BRG. The pinion shaft PS is formed in a columnar shape extending longitudinally in the direction of the rotation center Cp. Both ends in the longitudinal direction of the pinion shaft PS are fixed to a pair of carriers CA formed in a disc shape, respectively. The large-diameter pinion P1 and the small-diameter pinion P2 are integrally connected. The large-diameter pinion P1 and the small-diameter pinion P2 are provided on the outer side in the radial direction of the pinion shaft PS and are supported to be rotatable around the rotation center Cp. The large-diameter pinion P1 is a gear meshing with the sun gear S. The small-diameter pinion P2 is a gear meshing with the ring gear R. The needle bearing BRG includes a bearing disposed between the pinion shaft PS and the large-diameter pinion P1 and a bearing disposed between the pinion shaft PS and the small-diameter pinion P2.

[0023] The ring gear R is a gear that meshes with the sun gear S via a stepped pinion set SP. The ring gear R is an annular gear with inner teeth formed on its inner surface that mesh with a small-diameter pinion P2. The ring gear R is immobile by having its outer circumference fixed to the front case 22. The front planetary gear unit 52 configured as described above is a reduction gear that reduces the rotation of the front electric motor MGF and transmits it to the front differential gear 54.

[0024] The dog clutch 58 and actuator ACT are arranged in the direction of the rotation axis CL on the opposite side of the front electric motor MGF from the front planetary gear unit 52. The dog clutch 58 has a first dog tooth 58a and a second dog tooth 58b as opposing meshing teeth. The first dog tooth 58a is connected to a carrier CA that fixes the end of the pinion shaft PS on the opposite side of the front electric motor MGF, in a manner that prevents relative rotation. The second dog tooth 58b is connected to the front differential case 54c, which is the input rotating member of the front differential gear 54, in a manner that prevents relative rotation. The dog clutch 58 is engaged when the first dog tooth 58a and the second dog tooth 58b mesh together when the actuator ACT is operated, and is released when the meshing is disengaged.

[0025] The front drive unit 20 is further equipped with an electric oil pump 24 that discharges the inhaled oil FLD. The electric oil pump 24 discharges the oil FLD that has been inhaled from an oil reservoir (not shown) where oil FLD is collected, for example, located at the bottom of the front case 22. The oil FLD discharged from the electric oil pump 24 is supplied into the front case 22 (see arrows A and B). The oil FLD supplied into the front case 22 is used to lubricate the various parts of the front power transmission unit 50 (see arrows C, D, E, F, K, and L).

[0026] The front drive unit 20 further includes a lubrication oil passage 26 provided in the pinion shaft PS of the front planetary gear unit 52. The lubrication oil passage 26 includes an axial oil passage 26a and a radial oil passage 26b. The axial oil passage 26a is an oil passage that extends within the pinion shaft PS in the axial direction of the pinion shaft PS, that is, in the direction of the rotation center Cp. The axial oil passage 26a is an oil passage through which oil FLD discharged from the electric oil pump 24 is introduced. The radial oil passage 26b is an oil passage within the pinion shaft PS that is connected to the axial oil passage 26a and extends radially of the pinion shaft PS. The radial oil passage 26b is an oil passage through which oil FLD, which is led out from the axial oil passage 26a and supplied to the needle bearing BRG, flows. The needle bearing BRG is a component of the present invention that requires lubrication, and is supplied with oil FLD via the lubrication oil passage 26 (see arrows G, H, I, J).

[0027] The front electric motor MGF is the electric motor of the present invention. The front planetary gear system 52 is the planetary gear system of the present invention that transmits power from the front electric motor MGF to the front wheels 12. The front drive unit 20 is the drive unit of the present invention that has the front electric motor MGF, the front planetary gear system 52, an electric oil pump 24, a lubrication oil passage 26, and a needle bearing BRG. The front drive unit 20 further has a dog clutch 58.

[0028] The rear drive unit 30 does not have a disconnect mechanism such as a dog clutch 58, but its other configurations are the same as those of the front drive unit 20. For example, the rear drive unit 30 has an electric oil pump and lubrication passages (not shown), etc.

[0029] Returning to Figure 1, the electric vehicle 10 is further equipped with an electronic control unit 70 as a controller. The electronic control unit 70 is composed of a so-called microcomputer, which includes, for example, a CPU, RAM, ROM, input / output interface, etc. The CPU performs various controls of the electric vehicle 10 by performing signal processing according to a program stored in ROM in advance, while utilizing the temporary storage function of RAM. The electronic control unit 70 functions as a control device according to the present invention.

[0030] The electronic control unit 70 is supplied with various signals based on detection values ​​from various sensors provided in the electric vehicle 10. Examples of these sensors include the front motor rotation sensor 80, the rear motor rotation sensor 82, the vehicle speed sensor 84, the accelerator pedal position sensor 86, the G sensor 88, the yaw rate sensor 90, and the oil temperature sensor 92. Examples of these signals include the front motor rotation speed Nmgf, the rear motor rotation speed Nmgr, the vehicle speed V, the accelerator pedal position θacc, the longitudinal acceleration Gx, the lateral acceleration Gy, the yaw rate Ryaw, and the oil temperature THfld. The oil temperature THfld is the temperature of the oil FLD drawn in by the electric oil pump 24.

[0031] The electronic control unit 70 outputs various command signals to each device installed in the electric vehicle 10. These devices include, for example, the front power control unit PCUF, the rear power control unit PCUR, the electric oil pump 24, and the actuator ACT. The various command signals include, for example, the front motor control command signal Smgf, the rear motor control command signal Smgr, the pump control command signal Sop, and the clutch control command signal Sdc. The pump control command signal Sop is a control command signal for controlling the output of the electric oil pump 24. The clutch control command signal Sdc is a control command signal for controlling the switching between the engaged and disengaged states of the dog clutch 58.

[0032] The electronic control unit 70 includes a drive control unit 72, a driving state determination unit 74, a clutch control unit 76, and a lubrication control unit 78 in order to realize various controls in the electric vehicle 10.

[0033] The drive control unit 72 calculates the drive requirement DEM for the electric vehicle 10 by applying the accelerator opening θacc and vehicle speed V to a predetermined drive requirement map, for example. The drive requirement DEM can be, for example, the required driving force as the required value of the driving force at the wheels (front wheels 12, rear wheels 14). In the 2WD state, the drive control unit 72 controls the rear motor MGR by controlling the rear motor torque Tmgr to realize the drive requirement DEM. In the 4WD state, in addition to controlling the rear motor MGR, the drive control unit 72 controls the front motor MGF by controlling the front motor torque Tmgf to realize the drive requirement DEM. Note that unless otherwise specified, torque and force (driving force) are synonymous.

[0034] The driving state determination unit 74 determines whether to switch the drive state based on, for example, the vehicle speed V, the drive request amount DEM, the longitudinal acceleration Gx, the lateral acceleration Gy, the yaw rate Ryaw, etc. Switching the drive state is a switch between the 2WD state and the 4WD state. The 4WD state is a state in which the driving state of the electric vehicle 10 is an electric drive required state in which the drive of the electric motor by the front electric motor MGF is required, and a state in which the driving state of the electric vehicle 10 is a front drive required state in which the drive control of the front electric motor MGF is required. The driving state determination unit 74 determines whether the driving state of the electric vehicle 10 is a front drive required state or not. Hereinafter, unless otherwise specified, "driving state" refers to "the driving state of the electric vehicle 10".

[0035] The driving state determination unit 74 determines whether the driving state is a state requiring front drive based, for example, whether the vehicle speed V is equal to or greater than a predetermined first vehicle speed VH which determines the high vehicle speed range. The driving state determination unit 74 determines whether the driving state is a state requiring front drive based, for example, whether the vehicle speed V is equal to or less than a predetermined third vehicle speed VL which determines the low vehicle speed range. The driving state determination unit 74 determines whether the driving state is a state requiring front drive based on whether the drive request amount DEM is equal to or greater than a predetermined first request amount DEMH which determines the high load range.

[0036] If the driving state determination unit 74 determines that the driving state requires front drive, the drive control unit 72 drives the rear motor MGR and also drives the front motor MGF. If the driving state determination unit 74 determines that the driving state does not require front drive, the drive control unit 72 drives only the rear motor MGR and stops driving the front motor MGF.

[0037] The clutch control unit 76 controls the switching between the engaged and disengaged states of the dog clutch 58. When the driving state determination unit 74 determines that the driving state is a state requiring front drive, the clutch control unit 76 activates actuator ACT to engage the dog clutch 58. Engaging the dog clutch 58 is equivalent to connecting the dog clutch 58 to a connected state, where the power transmission path between the front planetary gear unit 52 and the front wheels 12 is connected. When the driving state determination unit 74 determines that the driving state is not a state requiring front drive, the clutch control unit 76 activates actuator ACT to disengage the dog clutch 58. Disengaging the dog clutch 58 is equivalent to disconnecting the dog clutch 58 to a disconnected state, where the power transmission path between the front planetary gear unit 52 and the front wheels 12 is disconnected.

[0038] The electric vehicle 10 operates in a 4WD state in a relatively low vehicle speed range of a predetermined third vehicle speed VL or less, a relatively high vehicle speed range of a predetermined first vehicle speed VH or more, or a relatively high load range of a predetermined first demand amount DEMH or more. The electric vehicle 10 operates in a relatively medium vehicle speed range of a predetermined third vehicle speed VL or less than a predetermined first vehicle speed VH, or a relatively low load range of a predetermined first demand amount DEMH or less.

[0039] The lubrication control unit 78 drives the electric oil pump 24 to supply oil FLD into the front case 22. When the electric vehicle 10 is in 4WD mode, the front planetary gear system 52 and other components are rotated, so lubrication by oil FLD is necessary. In 4WD mode, the pinion shaft PS of the front planetary gear system 52 is rotated, so oil FLD is supplied to the needle bearing BRG by centrifugal force via the lubrication oil passage 26. In 4WD mode, the lubrication control unit 78 performs drive control to drive the electric oil pump 24. When the driving state determination unit 74 determines that the driving state requires front drive, the lubrication control unit 78 performs a lubrication operation Mlub, which lubricates the needle bearing BRG by controlling the drive of the electric oil pump 24 and rotating the pinion shaft PS.

[0040] In the 2WD state of the electric vehicle 10, the rotating members of the front power transmission device 50 on the front planetary gear device 52 side and the front electric motor MGF are stopped from rotating more than the dog clutch 58, so lubrication by oil FLD is not necessarily required. The lubrication control unit 78 does not perform the lubrication operation Mlub in the 2WD state. The lubrication control unit 78 does not perform the lubrication operation Mlub if the driving state determination unit 74 determines that the driving state is not a state where front drive is required. The lubrication control unit 78 does not perform the lubrication operation Mlub by, for example, stopping the drive of the electric oil pump 24. In the 2WD state, the pinion shaft PS is not driven to rotate, but the front drive shaft 56 etc. are moved along with the front wheels 12, so some lubrication may be performed. When the lubrication operation Mlub is not performed, the lubrication control unit 78 may control the drive of the electric oil pump 24 at a reduced output compared to when the lubrication operation Mlub is performed.

[0041] In the 2WD state, when the dog clutch 58 is disengaged, the needle bearing BRG is in a poorly lubricated state. When the dog clutch 58 is switched from the disengaged state to the engaged state, if a load is applied while the needle bearing BRG remains in a poorly lubricated state, it may lead to a decrease in the durability of the needle bearing BRG.

[0042] The electronic control unit 70 performs pre-lubrication control, which involves pre-lubricating the needle bearing BRG when the vehicle approaches a state in which the dog clutch 58 is engaged while the dog clutch 58 is disengaged during driving. This prevents or suppresses the reduction in the durability of the needle bearing BRG due to the engagement of the dog clutch 58 in a poorly lubricated state.

[0043] When the driving state determination unit 74 determines that the driving state is not in a state requiring front drive, it determines whether the driving state has approached a state requiring front drive.

[0044] The driving state determination unit 74 determines, for example, whether the driving state is approaching the state requiring front drive when the vehicle speed V is less than a predetermined first vehicle speed VH, based on whether the vehicle speed V is equal to or greater than a predetermined second vehicle speed VHp. The predetermined second vehicle speed VHp is a value set lower than the predetermined first vehicle speed VH by a predetermined engagement preparation amount α. The predetermined engagement preparation amount α is a predetermined lubrication preparation amount to eliminate the poor lubrication state of the needle bearing BRG when the vehicle speed V approaches the predetermined first vehicle speed VH.

[0045] The driving state determination unit 74 determines whether the driving state is approaching the state requiring front drive, for example, when the vehicle speed V exceeds a predetermined third vehicle speed VL, based on whether the vehicle speed V is less than or equal to a predetermined fourth vehicle speed VLp. The predetermined fourth vehicle speed VLp is a value set higher than the predetermined third vehicle speed VL by a predetermined engagement preparation amount β. The predetermined engagement preparation amount β is a predetermined lubrication preparation amount to eliminate the poor lubrication state of the needle bearing BRG when the vehicle speed V approaches the predetermined third vehicle speed VL. The predetermined engagement preparation amount β may be the same value as the predetermined engagement preparation amount α, or it may be a different value from the predetermined engagement preparation amount α.

[0046] The driving state determination unit 74 determines whether the driving state is approaching the front drive requirement state, based on whether the drive requirement DEM is less than a predetermined first requirement DEMH and whether the drive requirement DEM is equal to or greater than a predetermined second requirement DEMHp. The predetermined second requirement DEMHp is a value set lower by a predetermined engagement preparation amount γ than the predetermined first requirement DEMH, for example. The predetermined engagement preparation amount γ is a predetermined lubrication preparation amount to eliminate the poor lubrication state of the needle bearing BRG when the drive requirement DEM approaches the predetermined first requirement DEMH.

[0047] When the electric vehicle 10 is traveling on an uphill road, it is considered that the driving state is more likely to become a state requiring front drive due to an increase in the drive requirement DEM compared to when it is traveling on a flat road. The driving state determination unit 74 determines whether the driving state is approaching a state requiring front drive, based on whether the road on which the electric vehicle 10 is currently traveling is an uphill road, when the drive requirement DEM is less than a predetermined first requirement DEMH. The driving state determination unit 74 determines whether the road on which the electric vehicle 10 is currently traveling is an uphill road, for example, based on whether it can be determined that the longitudinal acceleration Gx is small relative to the driving force.

[0048] When the driving state determination unit 74 determines that the driving state is approaching the state requiring front drive, the drive control unit 72 disengages the dog clutch 58 and drives the front electric motor MGF.

[0049] When the driving state determination unit 74 determines that the driving state is approaching the state requiring front drive, the lubrication control unit 78 releases the dog clutch 58 and performs the lubrication operation Mlub. In the lubrication operation Mlub performed when the vehicle is approaching the state requiring front drive, the lubrication control unit 78 controls the drive of the electric oil pump 24 with an increased output compared to when the vehicle is not in a state requiring front drive and is not approaching that state. For example, in the lubrication operation Mlub performed when the vehicle is approaching the state requiring front drive, the lubrication control unit 78 may control the drive of the electric oil pump 24 with an output similar to that when the vehicle is in a state requiring front drive.

[0050] If the vehicle approaches a state requiring front drive, and not much time has passed since the last lubrication operation (Mlub), the needle bearings (BRG) are not considered to be poorly lubricated, and therefore, lubrication operation (Mlub) is not necessary. By avoiding excessive drive control of the front electric motor (MGF), energy efficiency is improved.

[0051] When the driving state determination unit 74 determines that the driving state is not one in which front drive is required, it determines whether the elapsed time TMpas from the end of the lubrication operation Mlub by the lubrication control unit 78 is equal to or greater than a predetermined time TMf.

[0052] If the driving state determination unit 74 determines that the elapsed time TMpas is less than a predetermined time TMf, the drive control unit 72 stops driving the front electric motor MGF, even if it determines that the driving state is approaching the state requiring front drive. If the driving state determination unit 74 determines that the driving state is approaching the state requiring front drive AND that the elapsed time TMpas is equal to or greater than the predetermined time TMf, the drive control unit 72 drives the front electric motor MGF while the dog clutch 58 is released.

[0053] If the running state determination unit 74 determines that the elapsed time TMpas is less than a predetermined time TMf, the lubrication control unit 78 will not perform the lubrication operation Mlub, even if it determines that the running state is approaching the state requiring front drive. If the running state determination unit 74 determines that the running state is approaching the state requiring front drive AND that the elapsed time TMpas is equal to or greater than the predetermined time TMf, the lubrication control unit 78 will release the dog clutch 58 and perform the lubrication operation Mlub.

[0054] When the oil temperature THfld is low, the viscosity of the oil FLD increases, and the time required to lubricate the needle bearing BRG increases. To address this, the duration of the lubrication operation Mlub may be extended, or the output of the electric oil pump 24 may be increased. These measures also have the secondary effect of making it easier to raise the oil temperature THfld.

[0055] When the driving state determination unit 74 determines that the driving state is approaching the state requiring front drive, the lubrication control unit 78 increases the output of the electric oil pump 24 when performing the lubrication operation Mlub, compared to when the oil temperature THfld is high, if the oil temperature THfld is low.

[0056] The larger the predetermined engagement preparation values ​​α, β, and γ, the longer the lubrication operation Mlub is likely to be performed. The driving condition determination unit 74 sets the predetermined engagement preparation values ​​α, β, and γ to larger values ​​when the oil temperature THfld is low compared to when it is high.

[0057] The driving condition determination unit 74 determines whether the oil temperature THfld is below a predetermined oil temperature THfldf. The predetermined oil temperature THfldf is a predetermined low oil temperature determination value used, for example, to determine that the time required for lubrication of the needle bearing BRG will be extended.

[0058] When the running condition determination unit 74 determines that the oil temperature THfld is below a predetermined oil temperature THfldf, the lubrication control unit 78 increases the output of the electric oil pump 24 when performing the lubrication operation Mlub compared to when the oil temperature THfld is determined to be above the predetermined oil temperature THfldf.

[0059] If the driving state determination unit 74 determines that the oil temperature THfld is less than or equal to a predetermined oil temperature THfldf, it sets the predetermined engagement preparation amounts α, β, and γ to larger values ​​than when it determines that the oil temperature THfld exceeds the predetermined oil temperature THfldf.

[0060] Figure 3 is a flowchart illustrating the main parts of the control operation of the electronic control unit 70, and is a flowchart illustrating the control operation to suppress the decrease in durability of parts that require lubrication, and is repeatedly executed, for example, during driving when the dog clutch 58 is in an unengaged state. Figure 3 shows an embodiment that determines whether or not the vehicle speed is approaching a state where front drive is required. The unengaged state of the dog clutch 58 is synonymous with the released state of the dog clutch 58.

[0061] In Figure 3, first, in step S10, which corresponds to the function of the driving state determination unit 74 (the step will be omitted hereafter), it is determined whether the vehicle speed V is equal to or greater than a predetermined first vehicle speed VH. If the determination in S10 is affirmative, in S20, which corresponds to the functions of the drive control unit 72, clutch control unit 76, and lubrication control unit 78, the dog clutch 58 is engaged, the front electric motor MGF is driven, and the lubrication operation Mlub is performed. If the determination in S10 is negative, in S30, which corresponds to the function of the driving state determination unit 74, it is determined whether the vehicle speed V is equal to or greater than a predetermined second vehicle speed VHp. If the determination in S30 is affirmative, in S40, which corresponds to the function of the driving state determination unit 74, it is determined whether the elapsed time TMpas from the end of the lubrication operation Mlub is equal to or greater than a predetermined time TMf. If the determination in S30 is negative, or if the determination in S40 is negative, in S50, which corresponds to the function of the drive control unit 72, the drive of the front electric motor MGF is stopped. Next, in S60, which corresponds to the function of the lubrication control unit 78, the lubrication operation Mlub is not performed. If the judgment in S40 is affirmed, in S70, which corresponds to the function of the drive control unit 72, the dog clutch 58 is released and the front electric motor MGF is driven. Next, in S80, which corresponds to the function of the lubrication control unit 78, the lubrication operation Mlub is performed. Following S60, or following S80, in S90, which corresponds to the function of the clutch control unit 76, the dog clutch 58 is released.

[0062] Figure 4 is a flowchart illustrating the main parts of the control operation of the electronic control device 70, and is a flowchart illustrating the control operation to suppress the decrease in durability of parts that require lubrication, and is repeatedly executed, for example, during driving when the dog clutch 58 is in an unengaged state. The flowchart in Figure 4 is a different embodiment from the flowchart in Figure 3. Figure 4(a) shows an embodiment in which it is determined whether or not the vehicle is approaching the state in which front drive is required by low vehicle speed. Figure 4(b) shows an embodiment in which it is determined whether or not the vehicle is approaching the state in which front drive is required by the amount of drive required. Figure 4(c) shows an embodiment in which it is determined whether or not the vehicle is approaching the state in which front drive is required by uphill driving. In Figure 4, steps that are executed in place of S10 and S30 in Figure 3 are shown, and other omitted steps are the same as S20 and S40-S90 in Figure 3.

[0063] In Figure 4(a), first, in S110, which corresponds to the function of the driving state determination unit 74, it is determined whether the vehicle speed V is less than or equal to a predetermined third vehicle speed VL. If the determination in S110 is affirmative, S20 is executed. If the determination in S110 is negative, in S130, which corresponds to the function of the driving state determination unit 74, it is determined whether the vehicle speed V is less than or equal to a predetermined fourth vehicle speed VLp. If the determination in S130 is affirmative, S40 is executed. If the determination in S130 is negative, S50 is executed.

[0064] In Figure 4(b), first, in S210, which corresponds to the function of the driving state determination unit 74, it is determined whether the drive request amount DEM is equal to or greater than a predetermined first request amount DEMH. If the determination in S210 is affirmative, S20 is executed. If the determination in S210 is negative, in S230, which corresponds to the function of the driving state determination unit 74, it is determined whether the drive request amount DEM is equal to or greater than a predetermined second request amount DEMHp. If the determination in S230 is affirmative, S40 is executed. If the determination in S230 is negative, S50 is executed.

[0065] In Figure 4(c), first, in S310, which corresponds to the function of the driving state determination unit 74, it is determined whether the drive request amount DEM is equal to or greater than a predetermined first request amount DEMH. If the determination in S310 is affirmative, S20 is executed. If the determination in S310 is negative, in S330, which corresponds to the function of the driving state determination unit 74, it is determined whether the road is an uphill road. If the determination in S330 is affirmative, S40 is executed. If the determination in S330 is negative, S50 is executed.

[0066] Figure 5 is a flowchart illustrating the main parts of the control operation of the electronic control device 70, and is a flowchart illustrating the control operation for appropriately performing pre-lubrication control even at low oil temperatures, and is executed repeatedly. Figure 5(a) shows an embodiment for setting predetermined engagement preparation amounts α, β, and γ. Figure 5(b) shows an embodiment for setting the output of the electric oil pump 24.

[0067] In Figure 5(a), first, in S510, which corresponds to the function of the driving state determination unit 74, it is determined whether the oil temperature THfld is less than or equal to a predetermined oil temperature THfldf. If the determination in S510 is affirmative, then in S520, which corresponds to the function of the driving state determination unit 74, the predetermined engagement preparation amounts α, β, and γ are set to relatively large values. If the determination in S510 is negative, then in S530, which corresponds to the function of the driving state determination unit 74, the predetermined engagement preparation amounts α, β, and γ are set to relatively small values.

[0068] In Figure 5(b), first, in S610, which corresponds to the function of the driving state determination unit 74, it is determined whether the oil temperature THfld is below a predetermined oil temperature THfldf. If the determination in S610 is affirmative, in S620, which corresponds to the function of the lubrication control unit 78, the output of the electric oil pump 24 when performing the lubrication operation Mlub is increased to a relatively large value. If the determination in S610 is negative, in S630, which corresponds to the function of the lubrication control unit 78, the output of the electric oil pump 24 when performing the lubrication operation Mlub is decreased to a relatively small value.

[0069] As described above, according to this embodiment, when the driving state does not require front drive, the drive of the front electric motor MGF is stopped and the dog clutch 58 is disconnected. On the other hand, when the driving state does not require front drive, and the driving state approaches the state requiring front drive, the dog clutch 58 is disconnected, the front electric motor MGF is driven, and the lubrication operation Mlub is performed. This prevents or suppresses the fact that parts requiring lubrication are in a poorly lubricated state when the driving state becomes a state requiring front drive and power from the front electric motor MGF is transmitted to the front planetary gear unit 52. Therefore, a decrease in the durability of parts requiring lubrication can be suppressed.

[0070] Furthermore, according to this embodiment, if the elapsed time TMpas is less than a predetermined time TMf, the drive of the front electric motor MGF is stopped even if the driving state approaches the state requiring front drive. If the driving state approaches the state requiring front drive and the elapsed time TMpas is equal to or greater than the predetermined time TMf, the dog clutch 58 is disconnected, the front electric motor MGF is driven, and the lubrication operation Mlub is performed. This prevents or suppresses the driving of the front electric motor MGF more than necessary when lubricating parts that require lubrication, thereby improving energy efficiency.

[0071] Furthermore, according to this embodiment, when the driving condition approaches the state requiring front drive, the output of the electric oil pump 24 is increased when the oil temperature THfld is low compared to when it is high, during the lubrication operation Mlub. This addresses the issue that when the oil temperature THfld is low, the time required to lubricate the parts that need lubrication is prolonged.

[0072] Furthermore, according to this embodiment, whether or not the driving state requires front drive is determined based on whether or not the vehicle speed V is equal to or greater than a predetermined first vehicle speed VH. When the vehicle speed V is less than the predetermined first vehicle speed VH, whether or not the driving state is approaching the state requiring front drive is determined based on whether or not the vehicle speed V is equal to or greater than a predetermined second vehicle speed VHp. Alternatively, whether or not the driving state requires front drive is determined based on whether or not the vehicle speed V is equal to or less than a predetermined third vehicle speed VL. When the vehicle speed V exceeds the predetermined third vehicle speed VL, whether or not the driving state is approaching the state requiring front drive is determined based on whether or not the vehicle speed V is equal to or less than a predetermined fourth vehicle speed VLp. This allows for proper lubrication of parts that require lubrication when using vehicle speed V to determine whether or not the drive of the front electric motor MGF is required.

[0073] Furthermore, according to this embodiment, when the oil temperature THfld is low, the predetermined engagement preparation values ​​α, β, and γ are set to larger values ​​compared to when the oil temperature is high. This addresses the issue that when the oil temperature THfld is low, the time required to lubricate parts that require lubrication is increased.

[0074] Furthermore, according to this embodiment, whether the driving state is in a state requiring front drive is determined based on whether the drive requirement DEM is equal to or greater than a predetermined first requirement DEMH. When the drive requirement DEM is less than the predetermined first requirement DEMH, whether the driving state is approaching a state requiring front drive is determined based on whether the drive requirement DEM is equal to or greater than a predetermined second requirement DEMHp. Alternatively, when the drive requirement DEM is less than the predetermined first requirement DEMH, whether the driving state is approaching a state requiring front drive is determined based on whether the driving road is an uphill road. This allows for proper lubrication of parts that require lubrication when using the drive requirement DEM or the driving road to determine whether or not the front electric motor MGF needs to be driven.

[0075] Although embodiments of the present invention have been described in detail above with reference to the drawings, the present invention is also applicable to other embodiments.

[0076] For example, in the above-described embodiment, the parts requiring lubrication are not limited to the needle bearing BRG. For example, parts requiring lubrication include the bearing disposed between the large-diameter pinion P1 and the carrier CA that secures the end of the pinion shaft PS, and the bearing disposed between the small-diameter pinion P2 and the carrier CA that secures the end of the pinion shaft PS. These bearings are also supplied with oil FLD via the lubrication oil passage 26, similar to the needle bearing BRG.

[0077] Furthermore, in the above-described embodiment, for example, a drive unit (front drive unit 20) equipped with a disconnect mechanism (dog clutch 58) may drive the rear wheels 14, and a drive unit (rear drive unit 30) without a disconnect mechanism may drive the front wheels 12. Alternatively, for example, an engine may be used as the power source for the drive unit without a disconnect mechanism, in addition to or instead of an electric motor.

[0078] Furthermore, in the aforementioned embodiment, S40 in Figure 3 is not necessarily required. Even in this case, a certain effect can be obtained in which the reduction in the durability of parts requiring lubrication can be suppressed.

[0079] Furthermore, in the above-described embodiment, the present invention can be applied if the dog clutch 58 is provided in the power transmission path between the front planetary gear unit 52 and the front wheel 12.

[0080] It should be noted that the above-described embodiment is merely one example, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art. [Explanation of Symbols]

[0081] 10: Electric vehicle 12: Front wheel (drive wheel) 20: Front drive unit (drive unit) 24: Electric oil pump 26: Lubrication oil passage 26a: Axial oil passage 26b: Radial oil passage 52: Front planetary gear system (planetary gear system) BRG: Needle bearing (part requiring lubrication) PS: Pinion shaft 58: Dog clutch (disconnect mechanism) 70: Electronic control unit (control unit) FLD: Oil MGF: Front electric motor (electric motor)

Claims

1. An electric vehicle comprising: an electric motor; a planetary gear system for transmitting power from the electric motor to the drive wheels; an electric oil pump for discharging the drawn-in oil; a lubrication oil passage provided on the pinion shaft of the planetary gear system; a drive unit having a component that requires lubrication and to which the oil is supplied via the lubrication oil passage; and a control device, The drive unit further includes a disconnect mechanism provided in the power transmission path between the planetary gear system and the drive wheel, which disconnects the power transmission path. The lubrication oil passage includes an axial oil passage extending in the axial direction of the pinion shaft, through which the oil discharged from the electric oil pump is introduced, and a radial oil passage connected to the axial oil passage and extending radially of the pinion shaft, through which the oil led out from the axial oil passage and supplied to the component flows. The control device determines whether the driving state of the electric vehicle is in a state requiring electric drive, where the electric motor needs to be driven. When the control device determines that the driving state is a state requiring electric drive, it drives the electric motor, sets the disconnect mechanism to a connected state where the power transmission path is connected, and performs a lubrication operation by controlling the drive of the electric oil pump and rotating the pinion shaft to lubricate the components. If the control device determines that the driving state is not a state requiring electric drive, it stops the drive of the electric motor and sets the disconnect mechanism to a disconnected state in which the power transmission path is cut off. The control device determines whether the driving state has approached the state requiring electric drive when it has determined that the driving state is not the state requiring electric drive. The electric vehicle is characterized in that, when the control device determines that the driving state is approaching the state requiring electric drive, it drives the electric motor while disabling the disconnect mechanism, and also performs the lubrication operation.

2. The control device determines whether the elapsed time since the end of the lubrication operation is greater than or equal to a predetermined time when it determines that the driving state is not the state requiring electric drive. If the control device determines that the elapsed time is less than the predetermined time, it will stop the motor from driving, even if it determines that the driving state is approaching the state requiring electric drive. The electric vehicle according to claim 1, wherein the control device determines that the driving state is approaching the state requiring electric drive, and determines that the elapsed time is equal to or greater than the predetermined time, drives the electric motor while disabling the disconnect mechanism, and performs the lubrication operation.

3. The electric vehicle according to claim 1 or 2, characterized in that when the control device determines that the driving state is approaching the state requiring electric drive, it increases the output of the electric oil pump when the oil temperature is low compared to when it is high when performing the lubrication operation.

4. The control device determines whether the driving state is the state requiring electric drive based on whether the vehicle speed is equal to or greater than a predetermined first vehicle speed which determines the high vehicle speed range, and when the vehicle speed is less than the predetermined first vehicle speed, it determines whether the driving state is approaching the state requiring electric drive based on whether the vehicle speed is equal to or greater than a predetermined second vehicle speed which is set lower than the predetermined first vehicle speed by a predetermined amount for engagement preparation. Alternatively, the control device determines whether the driving state is the state requiring electric drive based on whether the vehicle speed is below a predetermined third vehicle speed for determining the low vehicle speed range, and when the vehicle speed exceeds the predetermined third vehicle speed, determines whether the driving state is approaching the state requiring electric drive based on whether the vehicle speed is below a predetermined fourth vehicle speed set to be higher than the predetermined third vehicle speed by a predetermined engagement preparation amount, characterized in that the electric vehicle according to claim 1 or 2.

5. The electric vehicle according to claim 4, characterized in that the control device sets the predetermined engagement preparation amount to a larger value when the oil temperature is low compared to when it is high.

6. The control device determines whether the driving state is the state requiring electric drive based on whether the drive request amount is equal to or greater than a predetermined first request amount that determines the high load range. The control device determines whether the driving state is approaching the state requiring electric drive, based on whether the drive request amount is less than the predetermined first request amount and is equal to or greater than a predetermined second request amount which is set lower than the predetermined first request amount by a predetermined engagement preparation amount. Alternatively, the electric vehicle according to claim 1 or 2, characterized in that when the drive request amount is less than the predetermined first request amount, the control device determines whether the driving state is approaching the electric drive requirement state based on whether the driving path is an uphill road.

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