Vehicle control device, vehicle control method, and program

Abstract

[PROBLEM] To enhance the operating efficiency of an electric oil pump. [SOLUTION] A vehicle control device is equipped with a unit having an electric oil pump and has a control unit for driving the electric oil pump in a case in which the vehicle has transitioned from a ready-off state to a ready-on state, and the ready-off state has been sustained for a prescribed time.

Description

Vehicle control device, vehicle control method, and program

[0001] The present invention relates to a vehicle control device, a vehicle control method, and a program.

[0002] Patent Document 1 discloses a powertrain unit for an electric vehicle in which oil for lubrication and cooling is supplied by an electric oil pump driven by a dedicated electric motor.

[0003] International Publication No. 2023 / 277058

[0004] The vehicle state can be switched between "Ready On," which indicates that the vehicle is ready to run, and "Ready Off," which indicates that the vehicle is not ready to run. "Ready On" is also called "Ignition On" in the case of an engine vehicle, and when in "Ready On," power is supplied to various auxiliary devices, enabling the vehicle to run.

[0005] On the other hand, when the engine is in ready-off mode, power is no longer supplied to the various accessories, and the electric oil pump no longer supplies lubricating oil, which can lead to an oil film breakdown (insufficient oil film) during the ready-off mode.

[0006] However, when the vehicle changes from a ready-off state to a ready-on state, driving the electric oil pump may result in excessive oil lubrication supply from the electric oil pump, and the power consumed by the excessive lubrication supply may reduce the operating efficiency of the electric oil pump.

[0007] The present invention has been made in view of the above problems, and has an object to improve the operating efficiency of an electric oil pump.

[0008] According to one aspect of the present invention, there is provided a control device for a vehicle equipped with a unit having an electric oil pump, the control device having a control unit that drives the electric oil pump when the vehicle changes from a ready-off state to a ready-on state and the ready-off state continues for a predetermined period of time.

[0009] According to the above aspect, when the ready-off state is short, the oil film is often not broken and oil lubrication supply is often not required, so the electric oil pump is driven when the ready-off state that has continued for a predetermined time changes to the ready-on state. As a result, if the ready-off state has not continued for the predetermined time, the electric oil pump does not need to be driven, thereby reducing unnecessary power consumption and improving the operating efficiency of the electric oil pump. Furthermore, since the operation of the electric oil pump affects the vehicle's noise and vibration performance, the frequency with which this performance is affected can also be reduced.

[0010] FIG. 1 is a schematic diagram showing the main parts of a vehicle. FIG. 2 is a diagram showing the lubrication and cooling path of a unit. FIG. 3 is an explanatory diagram of deterioration of operating efficiency. FIG. 4 is a flowchart showing an example of control in a ready-off state. FIG. 5 is a flowchart showing an example of control in a ready-on state. FIG. 6 is a diagram showing an example of a timing chart for a first case. FIG. 7 is a diagram showing an example of a timing chart for a second case. FIG. 8 is a flowchart showing a modified example of control performed by a controller.

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0012] 1 is a schematic diagram showing the main parts of a vehicle. Unit 1 is mounted on the vehicle and includes a motor 10 as a drive source that applies driving force to drive wheels 6, a speed reduction mechanism 20 that reduces the rotation speed from motor 10 and outputs it, a differential gear 30 that distributes the power transmitted from motor 10 via speed reduction mechanism 20 to the left and right drive wheels 6, a housing 40 that accommodates motor 10, speed reduction mechanism 20, and differential gear 30, and bearings 51 to 56 held in housing 40.

[0013] Motor 10 is a rotating electric machine and includes rotor 11, stator 12 that houses rotor 11, and rotating shaft 13 that rotates integrally with rotor 11. Stator 12 has coil ends 12a at both ends in the axial direction of motor 10, and rotating shaft 13 is supported by bearings 51 and 52 that are arranged on both sides of rotor 11 in the axial direction.

[0014] The reduction mechanism 20 is a gear mechanism and includes a first gear 21, a second gear 22, a third gear 23, and a fourth gear 24 arranged parallel to each other, and a shaft 25 on which the second gear 22 and the third gear 23 are mounted.

[0015] The first gear 21 is connected downstream (on the power output side) of the motor 10 and rotates integrally with the rotary shaft 13. The second gear 22 meshes with the first gear 21 and constitutes a first reduction gear stage together with the first gear 21. The second gear 22 rotates integrally with a shaft 25, which is supported at both ends by bearings 53 and 54.

[0016] The third gear 23 is connected downstream of the second gear 22 and rotates integrally with the shaft 25. The fourth gear 24 meshes with the third gear 23 and constitutes a second reduction gear stage together with the third gear 23. The fourth gear 24 is a final gear and is provided in the differential gear 30.

[0017] The differential gear 30 is a differential gear mechanism and has a differential case 31 that rotates integrally with the fourth gear 24. The differential case 31 is supported by bearings 55 and 56 and houses a differential portion that distributes the power input to the differential case 31 to the left and right drive wheels 6.

[0018] The housing 40 has a partition wall 41 that divides the interior of the housing 40. In the unit 1, the portion on the motor 10 side of the partition wall 41 (left side in FIG. 1 ) constitutes a motor section 1a that houses the motor 10, and the portion on the speed reduction mechanism 20 and differential gear 30 side of the partition wall 41 (right side in FIG. 1 ) constitutes a gear box section 1b that houses the speed reduction mechanism 20 and differential gear 30.

[0019] 2 is a diagram showing the lubrication and cooling paths of unit 1. Unit 1 further includes an electric oil pump 2 having an electric motor 2a as a power source separate from motor 10 as a drive source and an oil pump 2b driven by electric motor 2a, an inverter 3 that converts DC power from a battery into AC power and supplies it to electric motor 2a, a heat exchanger 4 that exchanges heat between coolant W and oil OL as a cooling medium, and a controller 5 that serves as a vehicle control device.

[0020] In the electric oil pump 2, an electric motor 2a receives power from an inverter 3 to drive an oil pump 2b. The electric oil pump 2 is connected to the motor section 1a and the gear box section 1b via a heat exchanger 4, draws oil OL from an oil reservoir section 42 of a housing 40 through a strainer 60, and supplies the drawn oil OL to the motor section 1a and the gear box section 1b.

[0021] In the motor section 1a, the oil OL from the electric oil pump 2 flows through the rotor 11 and the coil ends 12a in this order, and then returns to the oil reservoir 42. The rotor 11 and the coil ends 12a are cooled by the supplied oil OL.

[0022] In the gearbox section 1b, the oil OL from the electric oil pump 2 is distributed to the bearing section BRG including the bearings 51 to 56, the meshing portion E1 of the first gear 21 and the second gear 22, the meshing portion E2 of the third gear 23 and the fourth gear 24, and the differential gear 30, and after lubricating and cooling these, returns to the oil reservoir 42. The motor section 1a and the gearbox section 1b are also lubricated or cooled by the oil OL being scooped up in the oil reservoir 42 (scooped up by gears such as the fourth gear 24).

[0023] The heat exchanger 4 receives the oil OL from the electric oil pump 2 and the coolant W from the water pump 70, and the oil OL introduced into the heat exchanger 4 exchanges heat with the coolant W before being supplied to the motor section 1a and the gearbox section 1b. In the heat exchanger 4, when the temperature of the oil OL is higher than the temperature of the coolant W, the oil OL is cooled by the coolant W.

[0024] Coolant W from water pump 70 flows through inverter 80 for motor 10, stator 12, and heat exchanger 4 in this order, and then returns to water pump 70. The circulation path for coolant W may further include a battery, etc. In motor 10, oil OL supplied from electric oil pump 2 cools rotor 11 and coil ends 12a, and coolant W supplied from water pump 70, which is a pump separate from electric oil pump 2, cools stator 12.

[0025] The controller 5 performs control by executing a program stored in a ROM or RAM using a CPU. The program may be stored in a non-transitory storage medium such as a CD-ROM. The controller 5 is composed of one or more computers (microcomputers) equipped with a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface). The controller 5 may be composed of multiple controllers.

[0026] The vehicle state is switched between ready-on, which means the vehicle is ready to travel, and ready-off, which means the vehicle is not ready to travel, and signals are input to the controller 5 from a starter button 91, which is an operation unit for the user to instruct ready-on or ready-off, as well as from an accelerator opening sensor 92 for detecting an accelerator opening APO, a vehicle speed sensor 93 for detecting a vehicle speed VSP, etc. The controller 5 controls the inverter 3, thereby controlling the electric motor 2 a of the electric oil pump 2.

[0027] In the case of an engine vehicle, the "ready on" state is also called "ignition on" and, when the "ready on" state is in, for example, power is supplied to various auxiliary devices, allowing the vehicle to run. On the other hand, when the "ready off" state is in, power is no longer supplied to the various auxiliary devices and lubrication supply of oil OL from the electric oil pump 2 is no longer performed. For this reason, when the "ready off" state is in, an oil film shortage (insufficient oil film) may occur.

[0028] However, if the electric oil pump 2 is driven when the vehicle changes from a ready-off state to a ready-on state, in some cases the lubrication supply of oil OL from the electric oil pump 2 may become excessive, and the power consumed by the excessive lubrication supply may deteriorate the operating efficiency of the electric oil pump 2.

[0029] 3 is an explanatory diagram of the deterioration of driving efficiency. Ready (RDY) is a flag that is turned on or off by the user operating the starter button 91. When "Ready On" is instructed, it is turned on, and when "Ready Off" is instructed, it is turned off. Hereinafter, the electric oil pump 2 will also be simply referred to as the electric pump 2.

[0030] In this example, the decelerating vehicle stops at timing T1, and the electric pump 2 also stops in response to the vehicle stopping. After timing T1, the ready (RDY) signal changes from on to off at timing T2, and then turns on again a short time later (timing T3). When the ready-off state, which lasts only a short time, changes to the ready-on state in this manner, the oil film in the vehicle is often not broken, and there is often no need for lubrication supply of oil (OL).

[0031] However, in this example, when the ready RDY is turned on at timing T3, the electric pump 2 is operated to supply the oil OL as lubrication, which results in an excessive supply of the oil OL, and the power consumed by the excessive supply of lubrication reduces the operating efficiency of the electric pump 2.

[0032] Therefore, in this embodiment, the controller 5 performs the control described below.

[0033] 4 and 5 are flowcharts showing an example of control performed by the controller 5. Fig. 4 shows a first case in which the vehicle is in a ready-on state, and Fig. 5 shows a second case in which the vehicle is in a ready-off state. By executing the processes of these flowcharts, the controller 5 functions as a control unit that executes the processes (i.e., has a control unit that executes the processes).

[0034] As shown in Figure 4, when the vehicle is in the ready-on state, it is determined in step S1 whether the ready-RDY signal has changed from on to off. Whether the ready-RDY signal has changed from on to off can be determined based on a signal from the starter button 91. If the determination in step S1 is negative, the ready-on state continues, so the system operation is maintained and the process is temporarily terminated.

[0035] If the determination in step S1 is affirmative, the process proceeds to step S2 and then step S3. In step S2, the current time when the ready (RDY) signal changed from on to off (i.e., the current time when the ready-off command was issued) is stored (saved), and in step S3, the system is stopped. As a result, the vehicle enters the ready-off state.

[0036] In this way, when the vehicle changes from a ready-on state to a ready-off state, the controller 5 stores the current time, stops the system, and puts the vehicle into a ready-off state. After step S3, the process ends for the time being.

[0037] As shown in Figure 5, when the vehicle is in the ready-off state, it is determined in step S11 whether the ready RDY signal has changed from off to on. If the determination in step S11 is negative, the ready-off state continues, so the system remains stopped and the process ends. If the determination in step S11 is positive, the process proceeds to step S12, where the system is activated. This puts the vehicle into the ready-on state, and power is supplied to the electric pump 2.

[0038] In step S13, the time elapsed from when the ready-off state was entered until when the ready-on state was entered (in other words, the duration of the ready-off state) is calculated. The elapsed time is calculated based on the time stored in step S2 (i.e., the current time when the ready-off command was issued) and the current time when the ready RDY signal changed from off to on (i.e., the current time when the ready-on command was issued).

[0039] In step S14, it is determined whether the elapsed time calculated in step S13 is longer than a predetermined time α. The predetermined time α is a determination value for determining whether the oil film has been broken, and is set in advance.

[0040] If the determination in step S14 is affirmative, it is determined that the ready-off state has continued for the predetermined time α and the oil film has run out. In this case, since a supply of oil OL is required for lubrication, the process proceeds to step S15, where the electric pump 2 is operated (driven). This allows the gearbox portion 1b to be appropriately lubricated according to the state of the oil film.

[0041] If the determination in step S14 is negative, it is determined that the oil film is not broken. In this case, since the supply of lubrication oil OL is not necessary, the process is temporarily terminated. In other words, in this case, even if the ready-on state is entered, the electric pump 2 will not be operated (driven). This reduces unnecessary power consumption of the electric pump 2 and improves the operating efficiency of the electric pump 2. Furthermore, since the operation of the electric pump 2 affects the noise and vibration performance of the vehicle, the frequency with which the impact on noise and vibration performance is manifested can also be reduced.

[0042] In a vehicle, the elapsed time calculated in step S13 may be shorter than the predetermined time α when the ready RDY changes from off to on (a negative determination in step S14), and may then be longer than the predetermined time α (a positive determination in step S14). That is, in a vehicle, the ready RDY may turn on before the predetermined time α has elapsed, and after the vehicle changes from the ready-off state to the ready-on state, the predetermined time α may have elapsed since the start of the ready-off state.

[0043] In this case, the controller 5 drives the electric pump 2 in step S15, so that the electric pump 2 can be driven when the time comes for the oil film to run out after the vehicle has entered the ready-on state, thereby preventing the oil film from running out.

[0044] 6 and 7 are diagrams showing examples of timing charts corresponding to the control performed by the controller 5. Fig. 6 shows a case where the duration of the ready-off state is longer than the predetermined time α, and Fig. 7 shows a case where the duration of the ready-off state is shorter than the predetermined time α.

[0045] In the example shown in Figure 6, a decelerating vehicle stops at timing T11, and the electric pump 2 also stops in response to the vehicle stopping. After timing T11, the ready RDY changes from on to off at timing T12. If the ready-on state between timings T11 and T12 is long, lubrication supply of oil OL from the electric pump 2 can be performed separately. The ready RDY then changes from off to on at timing T13.

[0046] The time elapsed between timings T12 and T13 (duration of the ready-off state) is longer than a predetermined time α, which is preset to a length corresponding to the change in the oil film over time that will cause the oil film to break.

[0047] Therefore, at timing T13, the oil film is broken, and the electric pump 2 is driven to supply lubrication oil OL. At timing T13, the vehicle is stopped, and the electric pump 2 supplies the amount of oil OL necessary for lubrication to the gearbox portion 1b in preparation for the vehicle starting, and then stops. The electric pump 2 can be stopped when a predetermined time has elapsed since it started to be driven.

[0048] Thereafter, at timing T14, the vehicle starts accelerating, and the vehicle speed VSP starts to increase. At this time, each part of the gearbox section 1b is already lubricated by the oil OL from the electric pump 2 that was driven at timing T13, and is therefore protected from wear and the like. From timing T14, the gearbox section 1b enters a power transmission state, so the electric pump 2 is driven and the oil OL is supplied as lubrication to each part of the gearbox section 1b that is in the power transmission state.

[0049] 7, a decelerating vehicle stops at timing T21, and the electric pump 2 also stops in response to the vehicle stopping. After timing T21, the ready light changes from on to off at timing T22. The ready light then changes from off to on at timing T23, but the elapsed time between timings T22 and T23 (the duration of the ready-off state) is shorter than the predetermined time α, and the oil film is not broken at timing T23.

[0050] Therefore, at timing T23, the electric pump 2 is not driven, thereby reducing unnecessary power consumption of the electric pump 2 and improving the operating efficiency of the electric pump 2. Thereafter, at timing T24, the vehicle starts accelerating, and from timing T24 onwards, the electric pump 2 is driven to supply oil OL to the gear box 1b in the power transmission state as a lubricant.

[0051] Fig. 8 is a flowchart showing a modified example of the control performed by the controller 5. The flowchart shown in Fig. 8 is the same as the flowchart shown in Fig. 5 except for the addition of step S21, and therefore, the following description will mainly focus on step S21.

[0052] Following step S12, in step S21, it is determined whether the accelerator pedal is released. Whether the accelerator pedal is released can be determined based on a signal from the accelerator position sensor 92. If the determination in step S21 is positive, it is determined that the accelerator pedal is not being depressed, and the process proceeds to step S13.

[0053] If the determination in step S21 is negative, it is determined that the accelerator pedal is being depressed, and the electric pump 2 is driven in step S15. In other words, since depression of the accelerator pedal is a signal that the required flow rate of oil OL will increase, the controller 5 drives the electric pump 2 if the accelerator pedal is depressed after the vehicle has changed from the ready-off state to the ready-on state. This makes it possible to form an oil film in advance in preparation for an increase in the required flow rate of oil OL.

[0054] Next, the main effects of the controller 5 will be described.

[0055] (1) The controller 5 is a control device for a vehicle equipped with a unit 1 having an electric oil pump 2, and drives the electric oil pump 2 when the vehicle changes from a ready-off state to a ready-on state and the ready-off state continues for a predetermined time α.

[0056] With this configuration, if the ready-off state is short, the oil film is often not broken and lubrication supply of oil OL is often not required, so the electric oil pump 2 is driven when the ready-off state that has continued for the predetermined time α changes to the ready-on state. As a result, if the ready-off state has not continued for the predetermined time α, the electric oil pump 2 does not need to be driven, which reduces unnecessary power consumption and improves the operating efficiency of the electric oil pump 2. Furthermore, since the operation of the electric oil pump 2 affects the noise and vibration performance of the vehicle, the frequency with which this performance is affected can also be reduced.

[0057] (2) After the vehicle has transitioned from the ready-off state to the ready-on state, the controller 5 drives the electric oil pump 2 when a predetermined time α has elapsed since the start of the ready-off state.

[0058] According to this configuration, after the ready-on state is reached, the electric oil pump 2 is driven when the time for the oil film to run out is reached, thereby preventing the oil film from running out.

[0059] (3) The controller 5 may drive the electric oil pump 2 when the accelerator pedal is depressed after the vehicle has transitioned from the ready-off state to the ready-on state.

[0060] According to this configuration, when the accelerator pedal is depressed, it is used as a signal that the required flow rate of oil OL is increasing, and by driving the electric oil pump 2, it is possible to form an oil film in advance in preparation for an increase in the required flow rate of oil OL.

[0061] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

[0062] 1: Unit 2: Electric oil pump 5: Controller (vehicle control device, control unit) α: Predetermined time

Claims

1. A control device for a vehicle equipped with a unit having an electric oil pump, the control device having a control unit that drives the electric oil pump when the vehicle changes from a ready-off state to a ready-on state and the ready-off state continues for a predetermined time.

2. A vehicle control device as described in claim 1, wherein the control unit drives the electric oil pump when the predetermined time has elapsed since the start of the ready-off state after the vehicle has changed from the ready-off state to the ready-on state.

3. A vehicle control device according to claim 1, wherein the control unit drives the electric oil pump when the accelerator pedal is depressed after the vehicle has transitioned from the ready-off state to the ready-on state.

4. A method for controlling a vehicle equipped with a unit having an electric oil pump, comprising driving the electric oil pump when the vehicle changes from a ready-off state to a ready-on state and the ready-off state continues for a predetermined time.

5. A program executable by a computer of a control device of a vehicle equipped with a unit having an electric oil pump, the program including driving the electric oil pump when the vehicle changes from a ready-off state to a ready-on state and the ready-off state continues for a predetermined time.

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