WO2024062835A1

WO2024062835A1 - Vehicle control system

Info

Publication number: WO2024062835A1
Application number: PCT/JP2023/030540
Authority: WO
Inventors: 正徳 ▲高▼橋; 皓俊小川; 亮石橋
Original assignee: 株式会社Soken; 株式会社デンソー
Priority date: 2022-09-20
Filing date: 2023-08-24
Publication date: 2024-03-28

Abstract

This vehicle control system (1) controls drive of a vehicle (99) and comprises: a drive source (15), a friction clutch (31), a clutch actuator (35), and a control unit (50). The friction clutch (31) is disposed in a power transmission passage from the drive source (15) to drive wheels (11) so as to be capable of switching between engagement and disengagement of power transmission. The clutch actuator (35) drives the friction clutch (31). The control unit (50) controls drive of the drive source (15) and the clutch actuator (35). When the vehicle (99) traverses a level difference, the control unit (50) performs torque application control for controlling the revolution speed (Nmg) of the drive source and controlling the speed of clutch stroke for switching the state of the friction clutch (31) from an imperfect coupling state to a perfect coupling state.

Description

vehicle control system

Cross-reference of related applications

This application is based on patent application number 2022-149070 filed on September 20, 2022, and the contents thereof are hereby incorporated.

The present disclosure relates to a vehicle control system.

Conventionally, a control device is known that controls a running electric vehicle using the output torque of a motor. For example, in Patent Document 1, when there is a step on the road, a sudden acceleration start torque is calculated based on the inclination angle, and the motor is controlled. Furthermore, for example, in Patent Document 2, in a four-wheel drive electric vehicle in which a clutch is provided between the front wheels and the front wheel drive motor, when driving in sports mode, it is possible to drive in rear wheel drive by disengaging the clutch. It is.

Japanese Patent Application Publication No. 2014-231789 US Patent Application Publication No. 2020/0361465

In Patent Document 1, it is not possible to generate torque exceeding the upper limit torque of the motor, and there is a possibility that the motor cannot overcome the step. In this way, Patent Documents 1 and 2 do not mention clutch control that takes into consideration overcoming bumps and resonance of the drive system. An object of the present disclosure is to provide a vehicle control system that can appropriately control the drive of a vehicle.

The present disclosure is a vehicle control system that controls the drive of a vehicle, and includes a drive source, a friction clutch, a clutch actuator, and a control section. The friction clutch is provided in the power transmission path from the drive source to the drive wheels, and is capable of switching stages of power transmission. A clutch actuator drives a friction clutch. The control unit controls driving of the drive source and the clutch actuator.

In the first mode, the control unit performs torque application control to control the rotation speed of the drive source and the clutch stroke speed at which the friction clutch is switched from a non-fully engaged state to a fully engaged state when the vehicle goes over a step.

In the second aspect, the control unit increases the rotation speed of the drive source when the torque fluctuation frequency of the drive source is in the resonance region of the drive shaft connected to the drive wheel, and increases the rotation speed of the drive source and the drive shaft. The clutch stroke is controlled based on the difference in rotation speed. Thereby, the drive of the vehicle can be appropriately controlled.

The above objects and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. The drawing is
FIG. 1 is a schematic diagram showing a vehicle control system according to a first embodiment, FIG. 2 is a time chart illustrating behavior when it is not possible to get over a step due to insufficient torque. FIG. 3 is a flowchart illustrating clutch control according to the first embodiment, FIG. 4 is a map showing the relationship between clutch engagement time and inertia torque according to the first embodiment, FIG. 5 is a time chart illustrating clutch control according to the first embodiment, FIG. 6 is a time chart illustrating behavior when a step cannot be overcome due to lock protection control. FIG. 7 is a flowchart illustrating clutch control according to the second embodiment, FIG. 8 is a time chart illustrating clutch control according to the second embodiment, FIG. 9 is a map showing the relationship between clutch engagement time and rotational speed change amount according to temperature according to the third embodiment, FIG. 10 is a flowchart illustrating clutch control according to the third embodiment, FIG. 11A is a schematic diagram showing a state in which a vehicle crosses a step; FIG. 11B is a schematic diagram showing a state in which the vehicle has climbed over a step; FIG. 12 is a flowchart illustrating clutch control according to the fourth embodiment, FIG. 13 is a time chart illustrating clutch control according to the fourth embodiment, FIG. 14 is a flowchart illustrating clutch control according to the fifth embodiment, FIG. 15 is a time chart illustrating clutch control according to the fifth embodiment.

Hereinafter, a vehicle control device according to the present disclosure will be explained based on the drawings. Hereinafter, in a plurality of embodiments, substantially the same configurations are denoted by the same reference numerals, and description thereof will be omitted.

(First embodiment)
A vehicle control device according to a first embodiment is shown in FIGS. 1 to 6. As shown in FIG. 1, the vehicle control system 1 includes a front wheel drive section 10, a rear wheel drive section 20, a clutch 31, a clutch actuator 35, a control section 50, and the like.

The front-wheel drive unit 10 has a drive shaft 12 connected to the front wheels 11, a main motor 15, and a power transmission unit 18. The rear-wheel drive unit 20 has a drive shaft 22 connected to the rear wheels 21, a main motor 25, and a power transmission unit 28. The vehicle control system 1 of this embodiment is a so-called four-wheel drive system in which the

main motors

15, 25, which are drive sources, are provided on the front and rear wheel sides, respectively.

The

main motors

15 and 25 are so-called motors that function as electric motors that generate torque by being supplied with electric power from a battery (not shown), and as generators that are driven to generate electricity when the vehicle 99 is braked. It is a generator. The driving force of the main motor 15 is transmitted to the drive shaft 12 via the power transmission section 18, and rotates the front wheels 11. The driving force of the main motor 25 is transmitted to the drive shaft 22 via the power transmission section 28, and rotationally drives the rear wheels 21. The

power transmission units

18 and 28 are comprised of a speed reducer, a differential device that absorbs a difference in rotation between the left and right sides, and the like. Hereinafter, the front wheel drive unit 10 and the rear wheel drive unit 20 will be referred to as a "drive system", and the main motor will be referred to as an "MG".

The clutch 31 is provided in the front wheel drive unit 10 and can switch between connecting and disconnecting the main engine motor 15 and the front wheels 11. Specifically, the clutch 31 is provided on the drive shaft 12 between the differential gear and the front wheels 11. The clutch actuator 35 controls the stroke of the clutch 31 by applying a load to the clutch 31, and switches the clutch 31 between an engaged state and a released state.

The clutch 31 is a friction-type electric clutch, and by fully engaging it, it is possible to transmit the torque of the main motor 15 to the drive shaft 12, eliminating loss due to friction and the like. Further, by controlling the drive of the clutch actuator 35, it is possible to transmit a portion of the torque of the main engine motor 15 to the drive shaft, which is a so-called half-clutch state. In this embodiment, the engagement speed of the clutch 31 can be controlled by controlling the clutch actuator 35.

The control unit 50 is mainly composed of a microcomputer, and internally includes a CPU, ROM, RAM, I/O, and a bus line connecting these components, all of which are not shown. Each process in the control unit 50 may be a software process in which a CPU executes a program stored in a physical memory device such as a ROM (i.e., a readable non-temporary tangible recording medium), or It may also be a hardware process using a dedicated electronic circuit.

The control unit 50 detects

current sensors

61 and 63 that detect the current of the

main motors

15 and 25,

rotation angle sensors

62 and 64 that detect the rotation of the

main motors

15 and 25, a wheel speed sensor 65, and the temperature of the clutch 31. Detection values of the temperature sensor 67 and an accelerator opening sensor (not shown) that detects the pedal opening of the accelerator pedal 40 are acquired, and the driving of the

main engine motors

15 and 25 and the clutch actuator 35 is controlled. Control using the temperature sensor 67 will be described later in the fourth embodiment. Note that in the first embodiment and the like, the temperature sensor 67 may be omitted. In FIG. 1, the control unit 50 is shown as being one, but the functions may be divided into a plurality of ECUs or the like. Note that some control lines have been omitted to avoid complication.

Here, in a reference example in which the drive shaft and main motor cannot be separated by a clutch, the behavior when a step cannot be overcome due to insufficient torque will be explained based on the time chart of FIG. 2. In FIG. 2, the common time axis is set as the horizontal axis, and from the top, the accelerator opening, MG torque, MG rotation speed, and tire rotation speed are shown, and the top of the time chart shows the position of the front wheel 11 and the step corresponding to each time. The relationship is shown schematically. The same applies to FIG. When the drive shaft and the main engine motor are directly connected, the MG rotation speed and the tire rotation speed have similar behavior, although the values are different. Note that the MG rotation number is the number of rotations per unit time, and is a value that can be read as angular velocity.

It is assumed that before time x10, the accelerator pedal 40 is not depressed and the vehicle 99 is moving towards the step with creep torque. When the front wheel 11 hits a step at time x10, the rotation of the front wheel 11 and the main engine motor 15 is stopped.

When the driver has the intention of overcoming the step and depresses the accelerator pedal 40 at time x11, MG torque is generated by driving the main engine motor 15. Since the front wheel 11 was bent due to the weight of the vehicle, it gradually moves upward, and the front wheel 11 floats at time x12. Here, if the MG torque Tmg is insufficient for the step height h to be overcome, the rotation of the front wheel 11 stops at time x13, and thereafter, the front wheel 11 rotates in the opposite direction and falls to the ground at time x14. I can't get over the steps.

Therefore, in this embodiment, the engagement state of the clutch 31 is controlled when climbing over a step, and the inertia torque Ti obtained by changing the MG rotational speed Nmg is added to the MG torque Tmg. Makes it possible to get over steps. Equation (1) shows the inertia torque Ti that can be applied by changing the MG rotational speed Nmg. In the formula, Ti is inertial torque [N·m], I is inertial moment [kg·m ² ], and ω is angular velocity [rad/s]. The angular velocity ω is a value that can be converted into the MG rotational speed Nmg, and the inertia torque Ti that can be applied is determined by the rotational speed change amount ΔN and the clutch engagement time Δx. In this embodiment, the additional inertia torque Ti is controlled by controlling the rotation speed change amount ΔN and the clutch engagement time Δx.

Ti=I×dω/dt...(1)

The clutch control of this embodiment will be explained based on the flowchart of FIG. 3. This process is executed by the control unit 50 at a predetermined cycle. Hereinafter, "steps" such as step S101 will be omitted and simply referred to as "S".

In S101, the control unit 50 determines whether the MG torque Tmg is greater than zero. If it is determined that the MG torque Tmg is 0 (S101: NO), the process from S102 onwards is skipped. If it is determined that the MG torque Tmg is greater than 0 (S101: YES), the process moves to S102.

In S102, the control unit 50 determines whether the tire rotation speed Nt is smaller than a reference value Nref. The reference value Nref is set, for example, according to the vehicle speed at creep torque. If it is determined that the tire rotation speed Nt is equal to or greater than the reference value Nref (S102: NO), it is determined that the front wheel 11 has not hit a step, and the processing from S103 onwards is skipped. If it is determined that the tire rotation speed Nt is smaller than the reference value Nref (S102: YES), the process proceeds to S103. S101 and S102 are steps for determining whether the front wheel 11 has hit a step, and if the tire rotation speed Nt is smaller than the reference value Nref, it is assumed that some resistance is occurring.

In S103, the control unit 50 detects the step height h that the front wheels 11 collide with, for example, based on tire air pressure, etc., and calculates the required torque Tnec to overcome the step height h.

In S104, the control unit 50 determines whether the maximum torque Tmax that the main engine motor 15 can output is smaller than the required torque Tnec. If it is determined that the maximum torque Tmax is greater than or equal to the required torque Tnec (S104: NO), it is possible to overcome the step with the torque of the main engine motor 15, so the process from S105 onwards is skipped and torque application control is not performed. . If it is determined that the maximum torque Tmax is smaller than the required torque Tnec (S104: YES), the process moves to S105 and the clutch 31 is released. Here, it is desirable to release the clutch 31 as soon as possible.

In S106, the control unit 50 calculates the rotation speed change amount ΔN and the clutch engagement time Δx from the difference between the required torque Tnec and the maximum torque Tmax so that the inertia torque Ti can provide the insufficient torque. .

In FIG. 4, the horizontal axis is clutch engagement time Δx, and the vertical axis is inertia torque Ti, showing the relationship between the clutch engagement time and the inertia torque for each rotation speed change amount ΔN calculated by the inertia moment of the main motor 15 and the gear ratio of the reducer. For example, referring to point A, if the MG rotation speed Nmg is set to be 500 [rpm] higher than the target rotation speed Nmg ^* and the clutch 31 is engaged for a time xa [sec], an inertia torque of Ta [N·m] can be applied. That is, by having the relationship shown in FIG. 4 in advance in a map or the like, it is possible to calculate the rotation speed change amount ΔN and the clutch engagement time Δx from the torque Tnec required to overcome the step. The rotation speed change amount ΔN is the difference from the target rotation speed Nmg ^* after the step is overcome. The target rotation speed Nmg ^* after the step is overcome is, for example, a value corresponding to the vehicle speed (for example, 5 [km/h]) due to the creep torque.

Returning to FIG. 3, in S107 following S106, the control unit 50 performs MG rotational speed increase control. Specifically, the drive of the main engine motor 15 is controlled so that the MG rotational speed Nmg is higher than the target rotational speed Nmg ^* by a rotational speed change amount ΔN.

In S108, the control unit 50 determines whether the accelerator pedal 40 has been depressed within the determination time. Here, it is determined whether the driver has the intention to go over the bump, but the determination time is the time when the driver's intention can be determined, and the time when the rotation speed increase control can be continued with the clutch released. etc. will be set accordingly. If it is determined that the accelerator pedal 40 has been depressed within the determination time (S108: YES), the process proceeds to S109, and if it is determined that the accelerator pedal 40 has not been depressed within the determination time (S109: NO), the process proceeds to S110. Transition.

In S109, the control unit 50 controls the stroke speed of the clutch actuator 35 so that the clutch 31 is fully engaged during the clutch engagement time Δx. In S110, the control unit 50 returns the MG rotation speed Nmg to the target rotation speed Nmg ^* , and re-engages the clutch 31.

The clutch control of this embodiment will be explained based on the time chart of FIG. 5. In FIG. 5, the horizontal axis is the common time axis, and the accelerator opening, MG torque, clutch stroke, inertia torque, MG rotation speed, and tire rotation speed are shown from the top. Similar to FIG. 3, the top of the time chart shows the following: The positional relationship between the front wheel 11 and the step corresponding to each time is schematically shown. The same applies to FIG.

The behavior up to time x20 is similar to the behavior up to time x10 in FIG. At time x20, when the front wheel 11 hits a step, the rotation speeds of the front wheel 11 and the main engine motor 15 decrease. When the rotational speed becomes 0 at time x21, the clutch 31 is released. When the clutch release is completed at time x22, rotation speed increase control is performed so that the MG rotation speed Nmg becomes N ^* +ΔN.

At time x23, when the driver depresses the accelerator pedal 40, the clutch stroke is controlled so that the clutch 31 is gradually engaged over a clutch engagement time Δx. The change in the MG rotational speed Nmg during half-clutch control in which the clutch 31 is gradually engaged becomes the inertia torque Ti, which is added to the MG torque Tmg, so that the front wheel 11 that was floating at time x24 does not fall, and at time x25 Climbing over the steps is completed. Control after climbing over the step will be described later in the fourth embodiment.

In the present embodiment, by half-clutching the clutch 31 when climbing over a step, inertia torque Ti is applied in addition to the maximum torque Tmax of the main engine motor 15, so that it is possible to get over a higher step.

As explained above, the vehicle control system 1 of this embodiment controls the drive of the vehicle 99, and includes the main motor 15, the clutch 31, the clutch actuator 35, and the control section 50. The clutch 31 is provided in a power transmission path from the main engine motor 15 to the front wheels 11, and can switch between connecting and disconnecting power transmission. Since the clutch 31 is a friction clutch, half-clutch control is possible. Clutch actuator 35 drives clutch 31.

The control unit 50 controls the driving of the main engine motor 15 and the clutch actuator 35. When the vehicle 99 passes over a step, the control unit 50 performs torque application control that controls the MG rotational speed Nmg and the clutch stroke speed for switching the clutch 31 from a non-fully engaged state to a fully engaged state. Here, the "state where the clutch 30 is not fully engaged" includes a state where the clutch 30 is completely released and a half-clutch state. Thereby, the drive of the vehicle 99 can be appropriately controlled. Specifically, since it is possible to add an inertia torque amount to the torque of the main engine motor 15 as a driving torque by the torque application control, it is possible to improve the step-crossing performance.

The control unit 50 performs a rotational speed change that changes the rotational speed of the main motor 15 by engaging the clutch 31 in torque application control based on the necessary torque Tnec required for getting over the step and the maximum torque Tmax that can be output by the main motor 15. The amount ΔN and the clutch engagement time Δx are set. The clutch engagement time Δx is the time from when the MG rotational speed Nmg is larger than the target rotational speed Nmg ^* of the main engine motor 15 by the amount of rotational speed change ΔN until the clutch 31 is fully engaged. Thereby, the inertia torque Ti can be added to the drive torque by controlling the engagement state of the clutch 31 using the rotational speed change amount ΔN and the clutch engagement time Δx.

(Second embodiment)
A second embodiment is shown in FIGS. 6 to 8. In this embodiment, clutch control is performed so that the vehicle can overcome the bump while avoiding tire lock protection. First, the behavior when a step cannot be overcome by the lock protection control will be explained based on the time chart of FIG. 6.

The behavior from time x30 to time x32 is the same as from time x10 to time x12 in FIG. At time x32, if the torque is insufficient for the height of the step to be overcome, the front wheels 11 stop rotating at time x33. When the lock protection standby time XL has elapsed after the front wheel 11 stops rotating and enters the locked state, lock protection control intervenes at time x34. In the lock protection control, the MG torque Tmg is reduced even if the accelerator pedal 40 continues to be depressed. When the MG torque Tmg decreases, the front wheel 11 rotates in the opposite direction and falls to the ground at time x35. Further, the lock protection control ends at time x36 when the MG torque Tmg returns to a value corresponding to the accelerator opening degree. There are cases in which the vehicle can overcome a step by restoring the MG torque Tmg, but there are cases in which tire locking and lock protection control are repeated.

Therefore, in this embodiment, the engagement state of the clutch 31 is controlled so that the vehicle can overcome the step without lock protection control. Clutch control of this embodiment will be explained based on the flowchart of FIG. 7. The processing from S201 to S203 is similar to the processing from S101 to S103 in FIG.

In S204, similar to S108 in FIG. 3, the control unit 50 determines whether the accelerator pedal 40 has been depressed within the determination time. If it is determined that the accelerator pedal 40 has not been depressed within the determination time (S204: NO), the process from S205 onward is skipped. If it is determined that the accelerator pedal 40 has been depressed within the determination time (S204: YES), the process moves to S205.

In S205, the control unit 50 determines whether or not the tire is in a locked state based on the MG torque Tmg and the tire rotation speed Tn. When the MG torque Tmg is greater than or equal to the threshold value and the tire rotational speed Tn is less than or equal to the lock determination threshold value, which is set to an arbitrary value close to 0, it is determined that the tire is in a locked state. If it is determined that the tires are not in a locked state (S205: NO), the processes from S206 onwards are skipped. If it is determined that the tires are locked (S205: YES), the process moves to S206.

In S206, the control unit 50 performs half-clutch control on the clutch 31. Here, if the clutch 31 is disengaged, the torque will be lost, so it is not completely disengaged, but half-clutch control is performed with an arbitrary engagement force that can apply inertia torque by transitioning to full engagement. The processing in S207 to S209 is similar to the processing in S106, S107, and S109 in FIG.

The clutch control of this embodiment will be explained based on the time chart of FIG. 8. The behavior from time x40 to time x43 is the same as from time x30 to time x33 in FIG. When the lock state is reached at time x43, the clutch stroke is controlled to temporarily bring the clutch into a half-clutch state at time x44, which is a timing before the time when lock protection control intervenes. By setting the clutch 31 in a half-clutch state, the load is reduced, so the MG rotational speed Nmg increases.

At time x45 when the MG rotation speed Nmg becomes N ^* +ΔN due to the rotation speed increase control, the clutch stroke is gradually controlled so that the clutch 31 is re-engaged over a clutch engagement time Δx. The change in the MG rotational speed Nmg at this time becomes the inertia torque Ti, which is added to the MG torque Tmg. The clutch 31 is re-engaged at time x46, and climbing over the step is completed at time x47.

In the present embodiment, when the front wheels 11 become locked while climbing over a step, the clutch 31 is controlled to a half-clutch state. By setting the clutch 31 to half-clutch while going over a step, even if the front wheels 11 are locked, the main engine motor 15 can be rotated to avoid current concentration, and the intervention of lock protection control can be avoided. Can be done. In addition, by applying inertia torque Ti through torque application control after the clutch is in a half-clutch state, the front wheels 11 can overcome a step without falling. Further, the same effects as those of the above embodiment are achieved.

(Third embodiment)
A third embodiment is shown in FIGS. 9 and 10. In the embodiment described above, the additional inertia torque Ti is controlled by controlling the rotational speed change amount ΔN and the clutch engagement time Δx. Here, the kinetic energy K of the rotating body is shown in equation (2).

K=(1/2)×I×ω ² ...(2)

As shown in equation (2), kinetic energy K is proportional to the square of the angular velocity ω. Considering that kinetic energy is converted into frictional heat in half-clutch control according to the law of conservation of energy, the larger the rotational speed change amount ΔN is, the more likely the clutch temperature is to rise in torque application control.

FIG. 9 shows the relationship between the clutch engagement time Δx and the rotation speed change amount ΔN for each inertia torque Ti, with the horizontal axis representing the clutch engagement time Δx and the vertical axis representing the rotation speed change amount ΔN. For example, as shown at point C, when the rotational speed change amount ΔN is made smaller than that at point B, the inertia torque Ti can be made equal to that at point B by shortening the clutch engagement time ΔX. However, it must be noted that if the clutch engagement time Δx is too short, the engagement shock may increase and drivability may worsen.

Therefore, in this embodiment, the temperature difference Δtmp, the rotational speed change amount ΔN, and the clutch engagement time Δx are mapped, and based on the temperature difference Δtmp, which is the difference between the clutch temperature detected by the temperature sensor 67 and the outside air temperature, Set the rotational speed change amount ΔN and clutch engagement time Δx. For example, if the temperature difference Δtmp is 20°C, the rotational speed change ΔN and clutch engagement time Δx at point B, and if the temperature difference Δtmp is 40°C, the rotational speed change ΔN and clutch engagement time Δx at point C. And so on.

The clutch control of this embodiment will be explained based on the flowchart of FIG. 10. 10 differs from FIG. 3 in that S120 is added between S105 and S106. In S120, the control unit 50 calculates the temperature difference Δtmp based on the detected value of the temperature sensor 67. In S106, the control unit 50 calculates the rotational speed change amount ΔN and the clutch engagement time Δx based on the temperature difference Δtmp so that the inertia torque Ti can make up for the insufficient torque. Note that although the control of the first embodiment has been explained here as an example, in the control of the second embodiment, the rotational speed change amount ΔN and the clutch engagement time Δx may be set using the temperature difference Δtmp. .

In this embodiment, the vehicle control system 1 includes a temperature sensor 67 that detects the temperature of the clutch 31. In the torque application control, the control unit 50 controls the rotation speed of the main engine motor 15 and the clutch stroke speed based on the temperature of the clutch 31. Thereby, overheating of the clutch 31 can be prevented. Further, the same effects as those of the above embodiment are achieved.

(Fourth embodiment)
The fourth embodiment is shown in FIGS. 11A to 13. In this embodiment, control after getting over a step will be mainly described. Note that the control until the vehicle gets over the level difference may be any one of the first to third embodiments, or may be a control different from these.

FIGS. 11A and 11B schematically show the vehicle 99 climbing over a step, and the block arrows indicate the driving force of the front wheel drive section 10, the rear wheel drive section 20, and the vehicle as a whole. For example, when climbing over a bump in situations where the driver's intentions are difficult to reflect, such as during automatic operation of an electric vehicle, by reducing MG torque Tmg after climbing over the bump, excessive acceleration and sudden jump feeling after climbing over the bump can be suppressed. There is a need. In this embodiment, after completing the step over the step, the MG torque Tmg is reduced and the clutch 31 is disengaged, thereby further suppressing the feeling of jumping out after the step has been overcome.

Clutch control of this embodiment will be explained based on the flowchart of FIG. 12. In S301, the control unit 50 determines whether there is a step in the travel route. If it is determined that there is no level difference (S301: NO), the process from S302 onwards is skipped. In S302, for example, the level difference climbing control of the above embodiment is performed.

In S303, the control unit 50 determines whether the vehicle 99 has climbed over the step. If it is determined that the step has not been climbed over (S303: NO), the process returns to S302 and the step over-step control is continued. If it is determined that the step has been climbed over (S303: YES), the process moves to S304.

The control unit 50 releases the clutch 31 in S304, and performs MG rotation speed control in S305. When the clutch 31 is released and the load is removed, the MG rotation speed Nmg increases, so for example, the tire rotation speed Nt corresponding to the vehicle speed when driving at creep torque is converted into a value converted by the gear ratio of the reduction gear. The MG rotation speed Nmg is controlled as follows.

In S306, the control unit 50 determines whether the MG rotation speed Nmg has reached the target rotation speed Nmg ^* . Here, if the rotation speed is within a predetermined range including the target rotation speed Nmg ^* , an affirmative determination is made. If it is determined that the MG rotational speed Nmg is not the target rotational speed Nmg ^* (S306: NO), the process returns to S305 and the MG rotational speed control is continued. If it is determined that the MG rotation speed Nmg has reached the target rotation speed (S306: YES), the process moves to S307.

In S307, the control unit 50 determines whether the vehicle speed V is equal to or less than the vehicle speed determination threshold Vth. If it is determined that the vehicle speed V is greater than the vehicle speed determination threshold Vth (S307: NO), the process moves to S308, where brake control is performed to reduce the vehicle speed V. If it is determined that the vehicle speed V is less than or equal to the vehicle speed determination threshold Vth (S307: YES), the process moves to S309 and the clutch 31 is engaged.

The clutch control after going over a step will be explained based on the time chart in Figure 13. In Figure 13, the horizontal axis represents the common time axis, and from the top, the accelerator opening, MG torque, clutch stroke, brake torque, MG rotation speed, and tire rotation speed are shown.

At time x50, when the front wheels 11 pass over the step, the driver weakens the pedal effort, thereby reducing the accelerator opening and reducing the MG torque Tmg. At time x51, when it is determined that the vehicle has climbed over the step, the clutch 31 is released. Thereby, it is possible to suppress the feeling of jumping out after climbing over a step.

When the clutch 31 is released at time x51, the MG rotation speed Nmg increases, so the MG rotation speed is controlled so that the MG rotation speed Nmg becomes the target rotation speed Nmg ^* . Since the tire rotation speed Nt when the MG rotation speed Nmg becomes the target rotation speed Nmg ^* is larger than the tire rotation speed threshold TH corresponding to the vehicle speed determination threshold Vth, brake control is performed at time x52. At time x53 after the tire rotation speed Nt reaches the tire rotation speed threshold TH, the clutch 31 is engaged and normal control is returned to.

In the present embodiment, the control unit 50 releases the clutch 31 after the vehicle 99 gets over the step. By releasing the clutch 31 and disconnecting the main engine motor 15 and the drive shaft 12 after getting over the step, sudden acceleration after getting over the step is suppressed. This further improves vehicle safety after climbing over a bump. Further, the same effects as those of the above embodiment are achieved.

(Fifth embodiment)
A fifth embodiment is shown in FIGS. 14 and 15. When the clutch 31 is fully engaged while the vehicle 99 is running, etc., when the fluctuation period of the cogging torque or torque ripple of the main engine motor 15 is a rotational speed corresponding to the resonance frequency of the drive system, resonance occurs. Therefore, in this embodiment, resonance is avoided by controlling the MG rotational speed Nmg and the engagement state of the clutch 31.

Clutch control of this embodiment will be explained based on the flowchart of FIG. 14. In S401, the control unit 50 determines whether or not there is a command to engage the clutch 31. If it is determined that there is no command to engage the clutch 31 (S401: NO), the process from S402 onwards is skipped. If it is determined that there is a command to engage the clutch 31 (S401: YES), the process moves to S402.

In S402, the control unit 50 calculates the torque fluctuation frequency due to torque ripple and cogging torque based on the number of poles of the main motor 15, the MG rotation speed Nmg, etc. Note that a plurality of torque fluctuation frequencies may be calculated, such as a fluctuation frequency due to torque ripple and a fluctuation frequency due to cogging torque.

In S403, the control unit 50 determines whether the calculated torque fluctuation frequency corresponds to the resonance frequency of the drive system. Here, if the torque fluctuation frequency is within a predetermined range including the resonance frequency, an affirmative determination is made. Hereinafter, a predetermined range including the resonance frequency will be referred to as a "resonance region" as appropriate. If it is determined that the torque fluctuation frequency does not correspond to the resonance frequency of the drive system (S403: NO), the process moves to S404, the current MG rotational speed Nmg is maintained, and the clutch 31 is fully engaged. If it is determined that the torque fluctuation frequency corresponds to the resonance frequency of the drive system (S403: YES), the process moves to S405.

In S405, the control unit 50 calculates a target rotation speed Nmg ^* of the main motor 15 that is larger than the current MG rotation speed Nmg and at which the torque fluctuation frequency does not become the resonance frequency of the drive system.

In S406, the control unit 50 calculates a differential rotation speed vdef, which is the difference between the rotation speed of the drive shaft 12 corresponding to the target rotation speed Nmg ^* and the current rotation speed of the drive shaft 12. In S407, the control unit 50 calculates the friction coefficient μ at the differential rotation speed vdef from the μv characteristics of the clutch 31.

In S408, the control unit 50 calculates the target clutch load F ^* from the calculated friction coefficient μ and the current target drive torque Td ^* (Equation (3)). In equation (3), n is the number of plate sets in the clutch 31, and r is the clutch plate radius.

F ^* =Td ^* /(2×μ×n×r)...(3)

In S409, the control unit 50 calculates a target clutch stroke from the load-stroke characteristics of the clutch 31 using the target clutch load F ^* . In S410, the control unit 50 controls the main motor 15 and the clutch actuator 35 so that the MG rotational speed Nmg becomes the target rotational speed Nmg ^* and the clutch stroke becomes the target clutch stroke.

The clutch control of this embodiment will be explained based on the time chart of FIG. 15. In FIG. 15, the common time axis is the horizontal axis, and from the top, the vehicle speed, MG rotational speed, clutch stroke, and drive torque are shown. Here, the rotation speed of the main engine motor 15 on the front wheel side is shown as Nmg_f and the drive torque is shown as Td_f as a solid line, and the rotation speed of the main engine motor 25 on the rear wheel side is shown as Nmg_r and the drive torque is shown as Td_r as a dashed line. Note that this specification mainly describes the operation of the front wheel side where the clutch 31 is provided, and the subscripts _f and _r are omitted unless it is necessary to distinguish from the rear wheel side. In FIG. 14, the distribution ratio of the driving torque between the front and rear wheels is 1:1, but the ratio between the front and rear wheels may be different from 1:1.

Before time x60, the MG rotational speed Nmg is smaller than the rotational speed region where the torque fluctuation frequency corresponds to the resonance region (hereinafter simply referred to as the "resonance region"), so the MG rotational speed Nmg is changed to the rotational speed according to the vehicle speed. Then, the clutch 31 is fully engaged. When the MG rotational speed Nmg enters the resonance region at time x60, the rear wheel drive unit 20 side, which is not provided with a clutch, continues to control the MG rotational speed Nmg_r according to the vehicle speed.

On the other hand, on the front wheel drive unit 10 side where the clutch 31 is provided, the rotation speed Nmg_f of the main engine motor 15 is controlled to be above the resonance region. As a result, the output torque of the main motor 15 becomes larger than the required drive torque, so the clutch 31 is controlled to be a half-clutch so that the drive torque Td_f of the front wheel drive unit 10 becomes a torque in accordance with the request.

At time x61, when the MG rotational speed Nmg corresponding to the vehicle speed exceeds the resonance region, the half-clutch control is ended and the clutch 31 is fully engaged. Thereby, desired driving force can be transmitted to the drive system while avoiding resonance.

In this embodiment, when the torque fluctuation frequency of the main motor 15 is in the resonance region of the drive shaft 12 connected to the front wheels 11, the control unit 50 increases the rotation speed of the front wheels 11, and increases the rotation speed of the front wheels 11. The clutch stroke is controlled based on the difference from the rotation speed of the drive shaft 12. This suppresses resonance and improves comfort in the vehicle interior. Furthermore, the vehicle control system 1 of this embodiment is a four-wheel drive system, and by performing half-clutch control on the clutch 31, it is possible to continue four-wheel drive while avoiding resonance in the front wheel drive unit 10. This further improves vehicle stability.

In the embodiment, the clutch 31 corresponds to a "friction clutch" and the clutch 31 is provided in the front wheel drive unit 10, so the front wheel 11 is a "drive wheel", the drive shaft 12 is a "drive shaft", and the main engine motor 15 is a "drive wheel". Corresponds to "drive source".

(Other embodiments)
In the embodiment described above, the clutch is provided in the front wheel drive section. In other embodiments, the clutch may be provided on the rear wheel drive, or may be provided on the front wheel drive and the rear wheel drive. When a clutch is provided in the rear wheel drive unit, the rear wheel 21 corresponds to a "drive wheel," the drive shaft 22 corresponds to a "drive shaft," and the main motor 25 corresponds to a "drive source."

In the above embodiment, the vehicle drive system is a so-called four-wheel drive system in which the main motor serving as the drive source is provided in the front wheel drive section and the rear wheel drive section. In another embodiment, the vehicle drive system may be a so-called two-wheel drive system in which the main motor is provided in one of the front wheel drive section or the rear wheel drive section.

In the above embodiment, the clutch is provided on the drive shaft. In other embodiments, the clutch may be provided anywhere on the power transmission path from the drive source to the drive wheels, such as between the drive source and the reducer, between the reducer and the drive shaft, etc. good.

For example, the present disclosure may be as follows. "The controller further includes a temperature sensor (67) that detects the temperature of the friction clutch, and in the torque application control, the control unit controls the rotation speed of the drive source and the clutch stroke speed based on the temperature of the friction clutch." The vehicle control system according to any one of items 1 to 3, in which the control unit releases the friction clutch after the vehicle passes over a step. The vehicle control system described in this document.

The control unit and the method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor and a memory programmed to execute one or more functions embodied in a computer program. Alternatively, the control unit and the method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described in the present disclosure may be realized by one or more dedicated computers configured by combining a processor and a memory programmed to execute one or more functions with a processor configured with one or more hardware logic circuits. In addition, the computer program may be stored in a computer-readable non-transient tangible recording medium as instructions executed by a computer. As described above, the present disclosure is not limited to the above embodiments, and can be implemented in various forms within the scope of its purpose.

This disclosure has been described in accordance with embodiments. However, the present disclosure is not limited to such embodiments and structures. This disclosure also encompasses various modifications and variations within the range of equivalents. Various combinations and configurations, as well as other combinations and configurations including only one, more, or fewer elements, are also within the scope and spirit of the present disclosure.

Claims

A vehicle control system that controls the drive of a vehicle (99),
A driving source (15);
a friction clutch (31) provided in a power transmission path from the drive source to the drive wheels (11) and capable of switching connection/disconnection of power transmission;
a clutch actuator (35) that drives the friction clutch;
a control unit (50) that controls driving of the drive source and the clutch actuator;
Equipped with
The control unit performs vehicle control that performs torque application control to control the rotation speed of the drive source and the clutch stroke speed for switching the friction clutch from a non-fully engaged state to a fully engaged state when the vehicle overcomes a step. system.
The control unit is configured to control a rotational speed change amount for changing the rotational speed of the driving source in the torque application control based on the necessary torque required for getting over a step and the torque that can be outputted by the driving source, and the amount of rotational speed change of the driving source in the torque application control. The vehicle according to claim 1, wherein a clutch engagement time is set, which is the time from when the rotational speed of the drive source is higher than the target rotational speed by the amount of change in rotational speed until the friction clutch is fully engaged. control system.
The vehicle control system according to claim 1 or 2, wherein the control unit controls the friction clutch to be in a half-clutch state when the drive wheel is in a locked state while climbing over a step.
Further comprising a temperature sensor (67) that detects the temperature of the friction clutch,
The vehicle control system according to claim 1 or 2, wherein the control unit controls the rotation speed of the drive source and the clutch stroke speed based on the temperature of the friction clutch in the torque application control.
The vehicle control system according to claim 1, wherein the control unit releases the friction clutch after the vehicle passes over a step.
A vehicle control system that controls the drive of a vehicle (99),
A driving source (15);
a friction clutch (30) provided in a power transmission path from the drive source to the drive wheels (11) and capable of switching connection/disconnection of power transmission;
a clutch actuator (35) that drives the friction clutch;
a control unit (50) that controls driving of the drive source and the clutch actuator;
Equipped with
When the torque fluctuation frequency of the drive source is in a resonance region of a drive shaft (12) connected to the drive wheel, the control unit increases the rotation speed of the drive source, and increases the rotation speed of the drive source. A vehicle control system that controls a clutch stroke based on a difference between the rotation speed of the drive shaft and the rotation speed of the drive shaft.