JP7415997B2 - Vehicle control device and vehicle control method - Google Patents

Description

The present disclosure relates to a vehicle control device and a vehicle control method that can prevent a vehicle from rolling down, for example, on an uphill slope.

In vehicles equipped with conventional torque converters, creep torque acts upon starting. The effect of this creep torque prevents the vehicle from sliding downhill on an uphill slope at a predetermined angle or less.

In addition, as described in Patent Document 1, etc., by generating a relatively large creep torque and braking force after the brake pedal is released or when the force on the brake pedal becomes weak, it is possible to drive up a steep slope. Methods are also being considered to suppress the slippage.

JP2016-025683A

By the way, since the conventional skidding suppression control is performed based on the amount of operation of the brake pedal, it is difficult to apply it to a vehicle that performs full-vehicle speed ACC (Adaptive Cruise Control).

In other words, with full-vehicle speed ACC, automatic follow-up control is performed that corresponds to all vehicle speeds, including when the vehicle starts from a stopped state, so the driver does not have to release the brake pedal when starting. It is not possible to apply the slip control at the time of starting based on the opening timing of the vehicle as it is.

The present disclosure has been made in consideration of the above points, and provides a vehicle control device and a vehicle control method that can suppress the vehicle from sliding down when starting on a slope when full vehicle speed ACC is performed.

One aspect of the vehicle control device of the present disclosure is
A vehicle control device used for a vehicle that performs full-vehicle speed ACC (Adaptive Cruise Control),
a required driving force acquisition unit that obtains, as a required driving force, the driving force necessary to prevent the vehicle from sliding down based on the gradient resistance and rolling resistance of the stopped vehicle;
a driving force control unit that controls the actual driving force to be equal to or greater than the required driving force by controlling the output torque of the engine and the torque ratio of the torque converter based on the acquired required driving force;
a brake control unit that adjusts brake pressure based on the difference between the actual driving force and the required driving force;
Equipped with

One aspect of the vehicle control method of the present disclosure is
A vehicle control method used for a vehicle that performs full-vehicle speed ACC, the method comprising:
obtaining, as a required driving force, the driving force necessary to prevent the vehicle from sliding down based on the slope resistance and rolling resistance of the stopped vehicle;
controlling the actual driving force to be equal to or greater than the required driving force by controlling the output torque of the engine and the torque ratio of the torque converter based on the obtained required driving force;
adjusting brake pressure based on the difference between the actual driving force and the required driving force;
including.

According to the present disclosure, when full vehicle speed ACC is performed, it is possible to suppress the vehicle from sliding downward when starting on a slope.

An external view showing an example of a vehicle to which a vehicle control device according to an embodiment is applied. Block diagram showing the configuration of a vehicle according to an embodiment Block diagram showing the configuration of a vehicle control device according to an embodiment Diagram for explaining the operation of the vehicle control device according to the embodiment

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

<1> Configuration of Vehicle First, the configuration of a vehicle including a vehicle control device according to an embodiment of the present disclosure will be described.

FIG. 1 is an external view showing an example of a vehicle 1 to which a vehicle control device according to the present embodiment is applied. Further, FIG. 2 is a block diagram showing the configuration of the vehicle 1. As shown in FIG. Note that the vehicle 1 has a driving support device that executes full vehicle speed ACC, and herein, illustrations and explanations will be given focusing on parts related to the driving support device.

As shown in FIG. 1, a vehicle 1 is a tractor head (towing vehicle) that can connect and tow a trailer 2. The vehicle 1 includes a vehicle main body 3 including a power system such as an engine and drive wheels, and a driver's seat, and a trailer 2 connected to the vehicle main body 3.

As shown in FIG. 2, the vehicle 1 includes a drive system 10 for driving the vehicle 1, a braking system 20 for decelerating the vehicle 1, a driving support device 30 for supporting the driving of the vehicle 1 by the driver, and the like. As described above, the driving support device 30 executes full vehicle speed ACC.

The drive system 10 includes an engine 11, a clutch 12, a transmission 13, a propeller shaft 14, a differential gear 15, a drive shaft 16, wheels 17, an engine ECU 18, and a power transmission ECU 19. In this embodiment, clutch 12 is a torque converter.

The engine ECU 18 and the power transmission ECU 19 are connected to the driving support device 30 via an in-vehicle network such as a CAN (Controller Area Network), and are capable of mutually transmitting and receiving necessary data and control signals. The engine ECU 18 controls the output of the engine 11 according to a drive command from the driving support device 30. The power transmission ECU 19 controls the torque ratio (torque converter amplification factor) of the clutch 12 and the speed change of the transmission 13 in accordance with a drive command from the driving support device 30 .

Power from the engine 11 is transmitted to a transmission 13 via a clutch 12, which is a torque converter. The power transmitted to the transmission 13 is further transmitted to the wheels 17 via the propulsion shaft 14, the differential gear 15, and the drive shaft 16. Thereby, the power of the engine 11 is transmitted to the wheels 17, and the vehicle 1 runs.

The braking system 20 includes a regular brake 21, auxiliary brakes 22 and 23, a parking brake (not shown), and a brake ECU 24.

The service brake 21 is generally called a main brake, friction brake, foot brake, foundation brake, or the like. The service brake 21 is, for example, a drum brake that obtains braking force by pressing a brake lining against the inside of a drum that rotates together with the wheels 17.

The auxiliary brake 22 is a retarder that obtains braking force by directly applying a load to the rotation of the propulsion shaft 14 (hereinafter referred to as "retarder 22"), and is, for example, an electromagnetic retarder. The auxiliary brake 23 is an exhaust brake that enhances the effect of engine braking by using the rotational resistance of the engine (hereinafter referred to as "exhaust brake 23"). By providing the retarder 22 and the exhaust brake 23, the braking force can be increased and the frequency of use of the service brake 21 can be reduced, so wear and tear on the brake lining and the like can be suppressed.

The brake ECU 24 is connected to the driving support device 30 via an in-vehicle network such as CAN, and is capable of mutually transmitting and receiving necessary data and control signals. The brake ECU 24 controls the braking force of the service brake 21 (the brake fluid pressure of the wheel cylinder of the wheel 17) in accordance with a braking command from the driving support device 30.

The braking operation of the service brake 21 is controlled by the driving support device 30 and the brake ECU 24. The braking operations of the retarder 22 and the exhaust brake 23 are controlled on/off by the driving support device 30. Since the braking forces of the retarder 22 and the exhaust brake 23 are substantially fixed, the service brake 21, which can finely adjust the braking force, is suitable for generating a desired braking force accurately.

The driving support device 30 inputs information from a millimeter wave radar and a camera. Information from millimeter wave radar and cameras indicates the traffic and road conditions in front of the vehicle. The driving support device 30 also includes an ACC operation section 41, an accelerator operation detection section 43, a brake operation detection section 44, and the like.

The driving support device 30 forms control signals for controlling the operation of the drive system 10 and the brake system 20. Specifically, the driving support device 30 determines target acceleration/deceleration to achieve full vehicle speed ACC, and outputs these to the engine ECU 18, power transmission ECU 19, and brake ECU 24 as appropriate.

Although not shown, the engine ECU 18, the power transmission ECU 19, the brake ECU 24, and the driving support device 30 are, for example, a CPU (Central Processing Unit), a storage medium such as a ROM (Read Only Memory) storing a control program, Each has a working memory such as RAM (Random Access Memory) and a communication circuit. In this case, for example, the functions of each section that will be described later that constitute the driving support device 30 are realized by the CPU executing a control program. Note that all or part of the engine ECU 18, the power transmission ECU 19, the brake ECU 24, and the driving support device 30 may be integrally configured.

The ACC operation unit 41 includes an ACC on/off switch for starting and canceling the ACC. Further, the ACC operation unit 41 includes setting switches for performing various settings of the ACC. By operating a setting switch, the driver can set, for example, a target inter-vehicle distance and a target vehicle speed. Note that these switches may be embodied by a user interface displayed on a display with a touch panel.

The accelerator operation detection unit 43 detects the amount of depression of the accelerator pedal and outputs the detection result to the driving support device 30. The driving support device 30 sends a drive command to the engine ECU 18 and the power transmission ECU 19 based on the amount of depression of the accelerator pedal.

The brake operation detection unit 44 detects the amount of depression of the brake pedal for operating the service brake 21. Further, the brake operation detection unit 44 detects whether the auxiliary brake lever that operates the retarder 22 or the exhaust brake 23 is operated. Then, the brake operation detection unit 44 outputs the detection results regarding the brake pedal and the auxiliary brake lever to the driving support device 30. The driving support device 30 sends a braking command to the brake ECU 24 based on the amount of depression of the brake pedal. Further, the driving support device 30 controls the on/off operation of the retarder 22 or the exhaust brake 23 based on the operation of the auxiliary brake lever.

Further, the driving support device 30 outputs various information regarding driving and ACC from the information output unit 50. For example, the information output unit 50 outputs a display or sound indicating that the ACC is in operation or that the ACC is released.

<2> Description of vehicle control according to the present embodiment The vehicle control device 100 according to the present embodiment is provided within the driving support device 30.

FIG. 3 is a block diagram showing the configuration of the vehicle control device 100.

Vehicle control device 100 includes a required driving force acquisition section 110, a drive control section 120, and a brake control section 130.

The required driving force acquisition unit 110 obtains, as the required driving force, the driving force required to prevent the vehicle 1 from sliding down, based on the slope resistance and rolling resistance of the stopped vehicle 1.

The drive control unit 120 controls the output torque of the engine 11 and the torque ratio (torque converter amplification factor) of the torque converter (clutch 12) based on the required driving force acquired by the required driving force acquisition unit 110. Control is performed so that the driving force is greater than or equal to the required driving force.

The brake control unit 130 adjusts the brake pressure based on the difference between the actual driving force and the required driving force.

This will be explained more specifically.

The required driving force acquisition unit 110 inputs gradient information from, for example, an angle sensor (not shown) provided in the vehicle 1, and uses this to calculate gradient resistance. Gradient resistance is a force that causes the vehicle 1 to move down a slope. Gradient resistance Re [N] can be determined by Re=m×g×sin θ using vehicle total weight m [kg], inclination angle θ, and gravitational acceleration g [m/s ² ].

Further, the required driving force acquisition unit 110 calculates rolling resistance. Rolling resistance is mainly caused by energy loss due to tire deformation. The rolling resistance Rr [N] can be determined by Rr=μ×m×g using the vehicle total weight m [kg], the rolling resistance coefficient μ, and the gravitational acceleration g [m/s ² ].

The force with which the vehicle 1 tends to slide down on an uphill slope is equal to the slope resistance minus the rolling resistance. Therefore, the required driving force acquisition unit 110 obtains a value obtained by subtracting the rolling resistance from the gradient resistance as the required driving force.

In practice, among the parameters for determining the gradient resistance and rolling resistance described above, the parameters other than the inclination angle θ and the total vehicle weight m are almost constant values, so the required driving force acquisition unit 110 calculates the inclination angle θ and the total vehicle weight m The required driving force may be determined by storing other parameter values in advance and inputting the inclination angle θ and the vehicle gross weight m from a sensor (not shown).

The required driving force acquired by the required driving force acquisition section 110 is output to the drive control section 120 and the brake control section 130.

The drive control unit 120 outputs a control signal for controlling the engine 11 and the clutch 12 (torque converter) so that a driving force corresponding to the required driving force is transmitted to the wheels. The drive control unit 120 controls the engine 11 and the clutch 12 by outputting control signals to the engine ECU 18 and the power transmission ECU 19.

Specifically, the engine output torque and the torque ratio (torque converter amplification factor) are controlled by the drive control unit 120, the engine ECU 18, and the power transmission ECU 19 so that the following equations (1) and (2) are satisfied. Ru.

First, find the torque converter output torque that satisfies the following equation.
Required driving force [N] = (torque converter output torque - engine friction torque) x gear ratio
× Transmission efficiency × Final ratio ÷ Tire radius ………(1)

Next, the engine 11 and clutch 12 are controlled by determining engine output torque (torque converter input torque) and torque ratio (torque converter amplification factor) that satisfy the following equation.
Torque converter output torque [N・m]
= Engine output torque (torque converter input torque) x torque ratio (torque converter amplification factor)
‥‥‥(2)

By doing so, it is possible to prevent the vehicle 1 from sliding down.

However, since it is difficult to immediately obtain an actual driving force that corresponds to the required driving force, in this embodiment, sliding is prevented by coordinating with brake control.

FIG. 4 is a diagram for explaining the operation of the vehicle control device 100 according to the embodiment.

As a premise, it is assumed that the vehicle 1 is performing full speed ACC. It is also assumed that the vehicle 1 is stopped on an uphill slope due to traffic jams.

Assume that the preceding vehicle starts moving and the distance between the preceding vehicle and the preceding vehicle becomes equal to or greater than a predetermined distance at time t0. Then, the vehicle 1 starts a starting operation following the preceding vehicle.

First, during this start, the required driving force acquisition section 110 of the vehicle 1 outputs the required driving force to the drive control section 120 at time t0. In response to this requested driving force, the drive control unit 120 controls the output torque of the engine 111 and the torque ratio (torque converter amplification factor) of the clutch 112 so as to satisfy the requested driving force.

Through this control, the actual driving force increases. Eventually, at time t1, the actual driving force becomes equal to the required driving force. As a result, the vehicle 1 is in a state where it does not slide down even without the support of the brake after time t1. Therefore, the brake control unit 130 rapidly decreases the brake pressure by outputting a control signal for decreasing the brake pressure of the service brake 21 to the brake ECU 24 at time t1.

In other words, the brake control unit 130 adjusts the brake pressure to a predetermined value or higher at which the vehicle does not slide down until the actual driving force becomes equal to the required driving force, and after the actual driving force becomes equal to the required driving force, the brake pressure Make smaller.

In this way, the vehicle control device 100 determines the required driving force to prevent the vehicle 1 from sliding down, controls the engine 111 and the clutch 112 based on this required driving force, and adjusts the actual driving force to the required driving force. By releasing the brake when the vehicle reaches the maximum speed, it is possible to reliably prevent the vehicle from sliding downhill when starting on a slope in full-vehicle speed ACC mode.

<3> Effects of the Embodiment As described above, according to the present embodiment, the vehicle control device 100 used for the vehicle 1 that performs full-vehicle speed ACC is configured based on the slope resistance and rolling resistance of the stopped vehicle. A required driving force acquisition unit 110 obtains the driving force required to prevent the vehicle 1 from sliding down as the required driving force, and the output torque of the engine 111 and the torque of the torque converter (clutch 112) based on the acquired required driving force. A driving force control unit 120 that controls the actual driving force to be equal to or higher than the required driving force by controlling the ratio, and a brake control unit 130 that adjusts the brake pressure based on the difference between the actual driving force and the required driving force. By providing , it becomes possible to suppress the vehicle from sliding downward when starting on a slope when full vehicle speed ACC is performed.

The embodiments described above are merely examples of implementation of the present invention, and the technical scope of the present invention should not be construed as limited by these embodiments. That is, the present invention can be implemented in various forms without departing from its gist or main features.

In addition to the embodiments described above, the speed at which the brake pressure decreases may be changed depending on the distance from the preceding vehicle. In other words, the greater the distance from the preceding vehicle, the faster the brake pressure decreases. This makes it possible to improve the responsiveness of following the preceding vehicle.

In the embodiment described above, the brake control unit 130 reduces the brake pressure when the actual driving force becomes equal to the required driving force, but the brake control unit 130 is not limited to this, and the brake control unit 130 The brake pressure may be adjusted based on the difference between the force and the required driving force. For example, the brake pressure may be controlled to be smaller as the difference between the actual driving force and the required driving force becomes smaller.

The vehicle control device and vehicle control method of the present disclosure are widely applicable to vehicles that perform full-vehicle speed ACC.

1 Vehicle (own vehicle)
2 Trailer 3 Vehicle body 10 Drive system 11 Engine 12 Clutch 13 Transmission 14 Propulsion shaft 15 Differential device 16 Drive shaft 17 Wheels 18 Engine ECU
19 Power transmission ECU
20 Braking system 21 Regular brake 22 Retarder 23 Exhaust brake 24 Brake ECU
30 Driving support device 41 ACC operation section 43 Accelerator operation detection section 44 Brake operation detection section 50 Information output section 100 Vehicle control device 110 Requested driving force acquisition section 120 Drive control section 130 Brake control section

Claims (3)

A vehicle control device used for a vehicle that performs full-vehicle speed ACC (Adaptive Cruise Control),
a required driving force acquisition unit that obtains, as a required driving force, the driving force necessary to prevent the vehicle from sliding down based on the gradient resistance and rolling resistance of the stopped vehicle;
a driving force control unit that controls the actual driving force to be equal to or greater than the required driving force by controlling the output torque of the engine and the torque ratio of the torque converter based on the acquired required driving force;
a brake control unit that adjusts brake pressure based on the difference between the actual driving force and the required driving force;
Equipped with
In the starting operation from time t0 when the distance between the vehicle and the preceding vehicle becomes a predetermined distance or more while the vehicle is stopped,
The brake control unit controls the brake pressure to a constant value at which the vehicle does not slide down from the time t0 until the time t1 when the actual driving force becomes equal to the required driving force, and controls the brake pressure to a constant value that does not cause the vehicle to slide down. reduce brake pressure,
Vehicle control device. The brake control unit changes the speed at which the brake pressure decreases depending on the distance from the preceding vehicle.
The vehicle control device according to claim 1 . A vehicle control method used for a vehicle that performs full-vehicle speed ACC, the method comprising:
obtaining the driving force required to prevent the vehicle from sliding down as the required driving force, based on the gradient resistance and rolling resistance of the stopped vehicle;
controlling the actual driving force to be equal to or greater than the required driving force by controlling the output torque of the engine and the torque ratio of the torque converter based on the obtained required driving force;
adjusting brake pressure based on the difference between the actual driving force and the required driving force;
including;
In a starting operation from time t0 when the distance between the vehicle and the preceding vehicle becomes a predetermined distance or more while the vehicle is stopped,
The step of controlling the brake pressure includes controlling the brake pressure to a constant value at which the vehicle does not slide down from the time t0 until the time t1 when the actual driving force becomes equal to the required driving force, and controlling the brake pressure to a constant value at which the vehicle does not slide down. After that, reduce the brake pressure,
Vehicle control method.

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