Vehicle control device

Abstract

Provided is a vehicle control device that restricts the intervention (execution of traction control) of automatic control with respect to a driving operation for disengaging a host vehicle from a muddy state when the host vehicle is stuck by the muddy state. A vehicle control device (1) is provided with a processor capable of executing traction control for controlling a drive device of a vehicle so as to reduce the output of the drive device when a predetermined condition is satisfied. The processor is configured so as not to execute the traction control when the rate of change in the interval between the drive shaft side and the driven shaft side of the clutch exceeds a threshold value when the clutch of the host vehicle is connected during a predetermined period, and the number of times of switching the rotational direction of the drive wheels of the host vehicle during the predetermined period exceeds a threshold value.

Description

Technical Field

[0001] This invention relates to a vehicle control device for adjusting the output of the drive unit of the vehicle. Background Technology

[0002] A vehicle control device (see, for example, Patent Document 1 below) with the function of adjusting the rotational torque of the drive wheels of the vehicle has been proposed. This vehicle control device (hereinafter referred to as the "existing device") controls the vehicle's braking system by applying braking force to the drive wheels when the drive wheels of the vehicle enter mud and spin freely. This control is generally referred to as "traction control (TRC)".

[0003] [Existing Technical Documents]

[0004] [Patent Literature]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2016-190607 Summary of the Invention

[0006] However, typically, there is some looseness (gap) in the engaging parts (movable parts) of the components constituting the vehicle. When the vehicle starts or when the vehicle's direction of movement reverses (hereinafter referred to as "when the vehicle starts, etc."), the relative positions of the components change, their looseness decreases, and the components come into contact with each other (engage). For example, in the case of a sudden start of the vehicle, the components of the vehicle come into contact with each other violently. In this case, an impact (abnormal noise, vibration, etc.) may sometimes occur. Therefore, in order to suppress the generation of such impacts, the traction control of conventional devices is sometimes configured to include control that suppresses the sharp increase in the output of the drive unit during vehicle start-up, etc. That is, in vehicles using conventional devices, the drive unit is controlled in a way that the output of the drive unit does not increase as much even if the accelerator pedal is pressed deeply during vehicle start-up, etc.

[0007] Here, imagine a situation where the drive wheels are stuck in mud (the drive wheels spin freely due to the mud, preventing the vehicle from moving forward or backward). In this situation, sometimes performing a driving maneuver that causes the vehicle to rock back and forth can help it get out of the mud. Specifically, sometimes repeatedly shifting the gear from drive to reverse, then deeply pressing the accelerator pedal, immediately releasing it, then shifting back from reverse to drive and deeply pressing the accelerator pedal again can help the vehicle get out of the mud. If traction control (restraining the increase in driving force relative to the accelerator pedal pressure) is applied during such a driving maneuver, it may be difficult to make the vehicle rock back and forth, and it may be difficult to get the vehicle out of the mud.

[0008] One of the objectives of this invention is to provide a vehicle control device that, when a vehicle is stuck in mud, limits the intervention of automatic control for driving operations (execution of traction control) aimed at getting the vehicle out of the mud.

[0009] In order to achieve the above objectives, the vehicle control device (1) of the present invention includes a processor (10) which, under certain conditions, is capable of controlling the traction force of the drive device (30) of the vehicle (V0) in a manner that reduces the output of the drive device (30) of the vehicle (V0).

[0010] The processor is configured to not perform the traction control if, during a specified period (T), the rate of change (Δds) of the interval (Δd) between the drive shaft side and the driven shaft side of the clutch exceeds a threshold (Δdsth) and the number of times the rotation direction (ωd) of the drive wheel of the vehicle changes (Nωd) exceeds a threshold (Nωdth).

[0011] When the clutch plate interval changes significantly during clutch engagement, and the rotation direction of the drive wheels within the engine repeatedly reverses, the likelihood of the driver performing a driving operation to extricate the vehicle from the mud is high. According to the vehicle control device of the present invention, when the vehicle is stuck in mud, the automatic control intervention (execution of traction control) is limited for driving operations aimed at extricating the vehicle from the mud. Attached Figure Description

[0012] Figure 1 This is a block diagram of a vehicle control device according to one embodiment of the present invention.

[0013] Figure 2 This is a flowchart of a program executed by the CPU to implement the cancellation function.

[0014] [Explanation of reference numerals in the attached figures]

[0015] 1…Vehicle control unit, 10…ECU, 20…On-board sensors, 30…Drive unit Detailed Implementation

[0016] (In summary) One embodiment of the vehicle control device 1 of the present invention is applied, for example, to a vehicle V0 (hereinafter referred to as "the vehicle") equipped with an automatic driving function. The vehicle control device 1 has the function of controlling the idling of the vehicle's drive wheels and controlling the impact during start-up (traction control) when the automatic driving function is disabled (when the driver actively performs driving operations). Furthermore, the vehicle control device 1 restricts the execution of traction control when it determines that a driving operation for getting the vehicle out of mud is being performed.

[0017] (Specific structure) such as Figure 1 As shown, the vehicle control device 1 includes an ECU 10, on-board sensors 20, a drive unit 30, and a braking device 40.

[0018] ECU10 includes a microcomputer with CPU10a, ROM10b, RAM10c, timer 10d, etc. ECU10 is connected to other ECUs in the vehicle via CAN (Controller Area Network).

[0019] The vehicle-mounted sensors 20 include an accelerator pedal sensor 21, a wheel speed sensor 22, an acceleration sensor 23, a clutch sensor 24, and a mode selection switch 25.

[0020] Accelerator pedal sensor 21 detects the accelerator pedal depth AD of the vehicle and provides information representing the accelerator pedal depth AD to ECU 10.

[0021] The wheel speed sensor 22 includes a rotational speed measurement circuit and a wheel speed calculation device. The rotational speed measurement circuit includes a pulse generation circuit (a known encoding circuit) that outputs a pulse (electrical signal) whenever the vehicle's wheels rotate a predetermined angle, and a counting circuit that counts the number of these pulses. The wheel speed calculation device acquires the output value (number of pulses) of the counting circuit at a predetermined period (every unit of time) and resets the count value to "0". Based on the number of pulses per unit of time, the wheel speed calculation device acquires the rotational angular velocity ω of the wheel. Here, the pulses consist of a first pulse (phase A) and a second pulse (phase B) with a 90° phase offset. The wheel speed calculation device detects the rotational direction ωd of the drive wheel based on the timing (sequence of rising edges) of the transition from an off state to an on state of the first and second pulses. Furthermore, the wheel speed calculation device provides information indicating the acquired rotational angular velocity ω and rotational direction ωd to the ECU 10.

[0022] Acceleration sensor 23 includes a piezoelectric element. As the vehicle accelerates (or decelerates) in the longitudinal direction, the piezoelectric element deforms in the longitudinal direction, and its output voltage changes accordingly. Acceleration sensor 23 obtains the longitudinal acceleration α (absolute value) of the vehicle based on the output voltage of the piezoelectric element. Furthermore, acceleration sensor 23 provides information representing acceleration α to ECU 10.

[0023] Clutch sensor 24 is mounted on the clutch assembly constituting the drive unit 30 described later. Clutch sensor 24 detects the gap Δd between the clutch plate on the drive side and the clutch plate on the driven side, and provides information representing this gap Δ to ECU 10.

[0024] The mode selection switch 25 includes a switching device (lever) for selecting the operating mode (H4 / H2 / L4) of the transfer case, which will be described later.

[0025] The drive unit 30 imparts driving force to the drive wheels. The drive unit 30 includes an engine ECU, an internal combustion engine, and power transmission equipment (clutch assembly, transmission, drive shafts (front and rear drive shafts), etc.) that transmit the engine's output (driving force) to the drive wheels. The engine ECU obtains information (target value) indicating the target driving force and the target gear position from other ECUs (ECU10). Based on this information, it drives actuators that adjust the throttle opening of the internal combustion engine, actuators that switch the engagement / disengagement of the clutch plates of the clutch assembly, and actuators that change the gear engagement state of the transmission, thereby adjusting the driving force imparted to the drive wheels.

[0026] Additionally, the power transmission mechanism includes a transfer case. The transfer case includes an actuator that sets the vehicle's operating mode (drive mode) to any one of high-speed 4WD mode, high-speed 2WD mode, and low-speed 4WD mode. This operating mode is switched via the engine ECU. The engine ECU is connected to a mode selection switch and switches the operating mode (engine output transmission state) based on the mode selection signal output by the mode selection switch.

[0027] For example, when the mode selection switch is set to the H4 position, the transfer case is configured in a high-speed 4WD mode, transmitting engine output to both the front and rear drive shafts. Furthermore, when the mode selection switch is set to the H2 position, the transfer case is configured in a high-speed 2WD mode, transmitting engine output only to the rear drive shaft. Additionally, when the mode selection switch is set to the L4 position, the transfer case is configured in a low-speed 4WD mode, transmitting drive torque for low-speed, high-torque conditions to both the front and rear drive shafts, compared to the H4 position. The low-speed 4WD mode is suitable for off-road driving (scenarios where the vehicle is stuck in mud to get out of the mud).

[0028] Furthermore, when the vehicle using vehicle control device 1 is a hybrid electric vehicle (HEV), the engine ECU can control the driving force of the vehicle generated by either or both of the "internal combustion engine and electric motor" that serve as the vehicle's driving source.

[0029] Braking device 40 applies braking force to the wheels (brake discs). Braking device 40 includes a brake ECU, brake calipers, etc. The brake caliper includes an actuator that presses the brake pads against the brake disc. The brake ECU obtains information (target value) indicating the target braking force from other ECUs, and based on this information, drives the actuator of the brake caliper to adjust the braking force applied to the wheels (brake discs).

[0030] (Traction Adjustment Function) Next, the traction adjustment function of the vehicle control device 1 will be explained. The traction adjustment function includes idling suppression function and impact suppression function.

[0031] (Spinning Suppression Function) The ECU 10 determines whether the vehicle's drive wheels are spinning freely based on information obtained from the wheel speed sensor 22 and the acceleration sensor 23. Specifically, the ECU 10 determines that the drive wheels are spinning freely when the rate of change of the rotational angular velocity ωc exceeds the threshold ωcth and the acceleration α is below the threshold αth (even though the rotation of the drive wheels is increasing, the vehicle's speed hardly changes). In this case, the ECU 10 controls the braking device 40 to reduce the output of the drive unit 30 even when the accelerator pedal is depressed, thereby applying braking force to the drive unit 30. This suppresses the spinning of the drive wheels.

[0032] (Shock Suppression Function) The ECU10 controls the drive unit 30 to suppress a sharp increase in the driving force of the vehicle for a specified short period of time after the vehicle has just stopped and started moving forward / backward, or after the direction of travel has just reversed. As a result, when the vehicle starts, etc., the loosening of various parts (the gaps provided in the engagement parts of the components) is reduced, and the impact when the components come into contact with each other is reduced.

[0033] (Cancellation Function) The vehicle control unit 1 has a cancellation function that restricts (prohibits) the execution of traction control when a specified condition X, which is used to determine that "a driving operation for getting the vehicle out of mud is being performed," is met. Specifically, the ECU 10 sequentially obtains the position (H4 / H2 / L4), rotation direction ωd, and interval Δd of the mode selection switch 25 from the on-board sensor 20, and determines whether the following conditions X1 to X3 are met based on this information.

[0034] [Condition X1]...Mode selection switch 25 is set to position L4;

[0035] [Condition X2]... During the most recent specified period T (the period from past time ta to current time tb), the average rate of change Δds of the clutch plate interval Δd when the clutch is engaged exceeds the threshold Δdsth;

[0036] [Condition X3]...The number of times the rotation direction ωd is reversed Nωd during the most recent specified period T exceeds the threshold Nωdth.

[0037] Here, ECU10 acquires an interval Δd every minute time Δt and stores it in a ring buffer RB1 of a predetermined length (equivalent to the storage capacity of a predetermined period T) set in RAM10c. ECU10 calculates the average value of the rate of change Δds of interval Δd based on the time series data stored in the ring buffer RB1. Additionally, ECU10 acquires the rotation direction ωd every minute time Δt and stores it in RAM10c. ECU10 obtains the number of times the rotation direction ωd of the drive wheel reverses, Nωd, based on the time series data stored in the ring buffer RB2.

[0038] If conditions X1 to X3 are met, ECU10 determines that condition X is met. In this case, ECU10 restricts (prohibits) the execution of traction control.

[0039] Next, refer to Figure 2 The program PR1 executed by CPU 10a (hereinafter referred to as "CPU") to implement the above-mentioned cancellation function will be described. The CPU executes program PR1 every minute time interval Δt. The CPU starts executing program PR1 from step 100 and proceeds to step 101.

[0040] In step 101, the CPU determines whether the mode selection switch 25 is set to the L4 position. If the CPU determines that the mode selection switch 25 is set to the L4 position (101: Yes), it proceeds to step 102. On the other hand, if the CPU does not determine that the mode selection switch 25 is set to the L4 position (101: No), it proceeds to step 105.

[0041] In step 102, the CPU determines whether the average value of the rate of change Δds of the clutch plate interval Δd within a specified period T exceeds a threshold Δdsth. If the CPU determines that the average value of the rate of change Δds exceeds the threshold Δdsth (102: Yes), it proceeds to step 103. On the other hand, if the CPU does not determine that the average value of the rate of change Δds exceeds the threshold Δdsth (102: No), it proceeds to step 105.

[0042] In step 103, the CPU determines whether the number of times the rotation direction of the drive wheel changes, Nωd, within a specified period T exceeds the threshold Nωdth. If the CPU determines that the number of times the rotation direction of the drive wheel changes, Nωd, within the specified period T exceeds the threshold Nωdth (103: Yes), it proceeds to step 104. On the other hand, if the CPU does not determine that the number of times the rotation direction of the drive wheel changes, Nωd, within the specified period T exceeds the threshold Nωdth (103: No), it proceeds to step 105.

[0043] In step 104, the CPU disables the execution of traction control. Then, in step 105, the CPU enables the execution of traction control. Next, the CPU proceeds to step 106, where the execution of program PR1 is terminated.

[0044] (Effect) When the clutch plate gap Δd changes significantly during clutch engagement, and the rotation direction ωd of the drive wheel within the engine repeatedly reverses, the likelihood of the driver performing a driving operation to remove the vehicle from the mud is high. According to the vehicle control device 1, in the event that the vehicle is stuck due to mud, the automatic control intervention (execution of traction control) is limited for driving operations aimed at removing the vehicle from the mud.

[0045] (Modification) In the above embodiment, the ECU 10 obtains the rotation direction ωd of the drive wheel from the wheel speed sensor 22, and calculates the number of switching times Nωd based on the rotation direction ωd. Alternatively, the ECU 10 can calculate the number of switching times Nωd of the drive wheel rotation direction based on the gear position of the transmission and the depth of the accelerator pedal.

[0046] (Modification 2) ECU10 can also determine whether condition X is true regardless of the position of mode selection switch 25 (transferor setting state). That is, ECU10 can also determine that condition X is true if conditions X2 and X3 are true.

Claims

1. A vehicle control device comprising a processor, which, under predetermined conditions, is capable of controlling the traction force of the drive device in a manner that reduces the output of the drive device of the vehicle, wherein, The processor is configured to not perform traction control if, during a specified period, the rate of change of the interval between the drive shaft side and the driven shaft side of the clutch exceeds a threshold, and the number of times the rotation direction of the drive wheels of the vehicle changes during the specified period exceeds a threshold.

Images