Vehicle control apparatus

Abstract

PURPOSE: To provide a vehicle control apparatus that limits automatic control intervention (execution of traction control) with respect to driving operations for allowing the own vehicle to escape from mud when the own vehicle becomes stuck in the mud.SOLUTION: A vehicle control apparatus 1 includes a processor capable of executing traction control that controls a drive device such that an output of the drive device of the own vehicle is reduced when predetermined conditions are satisfied. The processor is configured not to execute the traction control when a rate of change in a distance between a drive shaft side and a driven shaft side of a clutch at a time of clutch engagement of the own vehicle within a predetermined period exceeds a threshold, and additionally, a number of switches in a rotation direction of a drive wheel of the own vehicle within the predetermined period exceeds a threshold.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device that adjusts the output of a drive device of a vehicle. [Background technology]

[0002] A vehicle control device has been proposed that has a function for adjusting the rotational torque of the drive wheels of the vehicle (see, for example, Patent Document 1 below). This vehicle control device (hereinafter referred to as the "conventional device") controls the braking device of the vehicle so that braking force is applied to the drive wheels when the drive wheels of the vehicle enter mud and spin. This control is generally referred to as "traction control (TRC)." [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-190607 Summary of the Invention

[0004] Generally, there is a backlash (gap) between the engaging portions (moving portions) of components constituting a vehicle. When the host vehicle starts moving or reverses its direction of movement (hereinafter referred to as "when the host vehicle starts moving, etc."), the relative positions of the components change, reducing the backlash and allowing the components to come into contact (engage) with each other. For example, when the host vehicle starts moving with force, the host vehicle's components come into contact with each other with force. In this case, shocks (such as abnormal noise and vibrations) may occur. Therefore, in order to suppress the occurrence of such shocks, the traction control of conventional devices may be configured to include control that suppresses a sudden increase in the output of the drive unit when the host vehicle starts moving, etc. In other words, in a vehicle to which a conventional device is applied, the drive unit is controlled so that the output of the drive unit does not increase too much even if the accelerator pedal is deeply depressed when the host vehicle starts moving, etc.

[0005] Here, when the drive wheels enter the mud, a situation is assumed in which the host vehicle becomes stuck in the mud (a situation in which the drive wheels spin in the mud, making it impossible to move the host vehicle forward or backward). In this situation, the host vehicle may be able to escape from the mud by performing a driving operation that rocks the host vehicle back and forth. Specifically, the host vehicle may be able to escape from the mud by repeatedly performing the following operations: switching the shift position from a forward position to a reverse position, deeply depressing the accelerator pedal, immediately thereafter releasing the accelerator pedal, returning the shift position from the reverse position to the forward position, and then deeply depressing the accelerator pedal again. If the above-mentioned traction control (suppressing the increase in driving force in response to depression of the accelerator pedal) is performed while performing such a driving operation, it may be difficult to rock the host vehicle back and forth, making it difficult to escape the mud.

[0006] One of the objects of the present invention is to provide a vehicle control device that, when the vehicle becomes stuck in mud, limits the intervention of automatic control (execution of traction control) in driving operations to allow the vehicle to escape from the mud.

[0007] In order to achieve the above object, the vehicle control device (1) of the present invention comprises: The vehicle includes a processor (10) capable of executing traction control for controlling a drive unit (30) of the vehicle (V0) so that the output of the drive unit (30) is reduced when a predetermined condition is met. The processor is configured not to execute the traction control when the rate of change (Δds) of the distance (Δd) between the drive shaft side and driven shaft side of the clutch of the host vehicle when the clutch is engaged within a predetermined period (T) exceeds a threshold value (Δdsth), and further when the number of times (Nωd) the direction of rotation (ωd) of the drive wheels of the host vehicle is changed within the predetermined period exceeds a threshold value (Nωdth).

[0008] If the rate of change in the clutch plate gap when the clutch is engaged is relatively large and the rotation direction of the drive wheels is repeatedly reversed within the engine, it is highly likely that the driver is performing a driving operation to get the vehicle out of the mud.With the vehicle control device according to the present invention, when the vehicle becomes stuck in mud, intervention of automatic control (execution of traction control) in the driving operation to get the vehicle out of the mud is limited. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram of a vehicle control device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a flowchart of a program executed by the CPU to realize the cancel function. DETAILED DESCRIPTION OF THE INVENTION

[0010] (Summary) A vehicle control device 1 according to one embodiment of the present invention is applied to, for example, a vehicle V0 (hereinafter referred to as "host vehicle") equipped with an automatic driving function. The vehicle control device 1 has a function (traction adjustment function) that executes control to suppress spin of the drive wheels of the host vehicle and control to suppress shocks at the time of starting, etc., when the automatic driving function is disabled (when the driver is actively performing driving operations). Furthermore, the vehicle control device 1 restricts the execution of traction control when it determines that a driving operation is being performed to get the host vehicle out of mud.

[0011] (Specific Configuration) As shown in FIG. 1, the vehicle control device 1 includes an ECU 10, an on-vehicle sensor 20, a drive device 30, and a braking device 40.

[0012] The ECU 10 includes a microcomputer equipped with a CPU 10a, a ROM 10b, a RAM 10c, a timer 10d, etc. The ECU 10 is connected to other ECUs provided in the vehicle via a CAN (Controller Area Network).

[0013] The on-vehicle 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 .

[0014] The accelerator pedal sensor 21 detects the depression depth AD of the accelerator pedal of the host vehicle, and provides the ECU 10 with information indicating the depression depth AD.

[0015] 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 well-known encoder circuit) that outputs a pulse (electrical signal) each time a wheel of the vehicle rotates by a predetermined angle, and a counter circuit that counts the number of pulses. The wheel speed calculation device acquires the output value (number of pulses) of the counter circuit at a predetermined cycle (each unit time elapses) and resets the count value to "0." The wheel speed calculation device acquires the rotational angular velocity ω of the wheel based on the number of pulses per unit time. Here, the pulses consist of a first pulse (A-phase) and a second pulse (B-phase) that are 90° out of phase with each other. The wheel speed calculation device detects the rotational direction ωd of the drive wheels based on the transition timing (the order of rising edges) of the first and second pulses from an OFF state to an ON state. The wheel speed calculation device then provides the ECU 10 with information representing the acquired rotational angular velocity ω and rotational direction ωd.

[0016] The acceleration sensor 23 includes a piezoelectric element. When the host vehicle accelerates (or decelerates) in the longitudinal direction, the piezoelectric element deforms in the longitudinal direction (longitudinal direction) of the host vehicle, and the output voltage of the piezoelectric element changes in accordance with the deformation. The acceleration sensor 23 acquires the longitudinal acceleration α (absolute value) of the host vehicle based on the output voltage of the piezoelectric element. The acceleration sensor 23 then provides information representing the acceleration α to the ECU 10.

[0017] The clutch sensor 24 is incorporated in a clutch device that constitutes the drive unit 30, which will be described later. The clutch sensor 24 detects the gap Δd between the drive-side clutch plate and the driven-side clutch plate, and provides the ECU 10 with information indicating the gap Δ.

[0018] The mode selection switch 25 includes a switch device (lever) used to select an operation mode (H4 / H2 / L4) of the transfer case, which will be described later.

[0019] The drive unit 30 applies a driving force to the drive wheels. The drive unit 30 includes an engine ECU, an internal combustion engine (engine), and a power transmission (clutch device, transmission, drive shafts (front wheel drive shaft and rear wheel drive shaft), etc.) that transmits the engine output (driving force) to the drive wheels. The engine ECU acquires information (target value) indicating a target driving force, a target shift position, etc. from another ECU (ECU 10), and based on this information, drives an actuator that adjusts the throttle valve opening of the internal combustion engine, an actuator that switches the engagement / disengagement of the clutch plates of the clutch device, an actuator that changes the meshing state of the gears of the transmission, etc., to adjust the driving force applied to the drive wheels.

[0020] The power transmission mechanism includes a transfer case. The transfer case includes an actuator that sets the vehicle's operating mode (drive mode) to one of high-speed 4WD mode, high-speed 2WD mode, and low-speed 4WD mode. The operating mode is switched by the engine ECU. The engine ECU is connected to a mode selection switch and switches the operating mode (transmission state of the engine's output) based on a mode selection signal output by the mode selection switch.

[0021] For example, when the mode selector switch is set to the H4 position, the transfer case is set to a high-speed 4WD mode in which engine output is transmitted to the front and rear drive shafts. When the mode selector switch is set to the H2 position, the transfer case is set to a high-speed 2WD mode in which engine output is transmitted only to the rear drive shaft. When the mode selector switch is set to the L4 position, the transfer case is set to a low-speed 4WD mode in which a drive torque for lower vehicle speeds and higher torque than that in the H4 position is transmitted to the front and rear drive shafts. The low-speed 4WD mode is suitable for off-road driving (e.g., when getting a vehicle stuck in mud out of the mud).

[0022] Furthermore, if the vehicle to which the vehicle control device 1 is applied is a hybrid 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" as the vehicle driving source.

[0023] The braking device 40 applies braking force to the wheels (brake discs). The braking device 40 includes a brake ECU, a brake caliper, etc. The brake caliper includes an actuator that presses brake pads against the brake discs. The brake ECU acquires information (target value) indicating a target braking force from another ECU, and based on that information, drives the actuator of the brake caliper to adjust the braking force applied to the wheels (brake discs).

[0024] (Traction Adjustment Function) Next, a description will be given of the traction adjustment function of the vehicle control device 1. The traction adjustment function includes a spin suppression function and a shock suppression function.

[0025] (Spinning Suppression Function) The ECU 10 determines whether the drive wheels of the vehicle are spinning based on information acquired from the wheel speed sensor 22 and the acceleration sensor 23. Specifically, the ECU 10 determines that the drive wheels are spinning (the speed of the vehicle is barely changing despite the increased rotation of the drive wheels) when the rate of change ωc of the rotational angular velocity ω exceeds a threshold ωcth and the acceleration α is equal to or less than a threshold αth. In this case, the ECU 10 reduces the output of the drive unit 30 even if the accelerator pedal is depressed, and further controls the brake unit 40 so that a braking force is applied to the drive unit 30. This suppresses spinning of the drive wheels.

[0026] (Shock suppression function) The ECU 10 controls the drive unit 30 so that a sudden increase in the driving force of the vehicle is suppressed for a predetermined short period of time immediately after the vehicle has stopped and started to move forward / backward from a standing position, or immediately after the vehicle has reversed its direction of travel. This reduces the backlash of each part (the gap between the engaging parts of the parts) when the vehicle starts moving, thereby reducing the shock when parts come into contact with each other.

[0027] (Cancellation Function) The vehicle control device 1 has a cancellation function that restricts (prohibits) the execution of traction control when a predetermined condition X is met for determining that "a driving operation is being performed to get the host vehicle out of the mud." Specifically, the ECU 10 sequentially acquires the position (H4 / H2 / L4) of the mode selection switch 25, the rotation direction ωd, and the interval Δd from the on-board sensor 20, and determines whether the following conditions X1 to X3 are met based on this information. [Condition X1]...The mode selection switch 25 is set to the L4 position. [Condition X2]: The average value of the rate of change Δds of the clutch plate clearance Δd when the clutch is engaged during the most recent predetermined period T (the period from past time ta to present time tb) exceeds the threshold value Δdsth. [Condition X3]: The number of times Nωd that the rotation direction ωd has reversed in the most recent predetermined period T exceeds a threshold value Nωdth. Here, the ECU 10 acquires the interval Δd every time an infinitesimal time Δt elapses and stores it in a ring buffer RB1 of a predetermined length (storage capacity equivalent to a predetermined period T) provided in the RAM 10c. The ECU 10 calculates the average value of the rate of change Δds of the interval Δd based on the time series data stored in the ring buffer RB1. The ECU 10 also acquires the rotation direction ωd every time an infinitesimal time Δt elapses and stores it in the RAM 10c. The ECU 10 acquires the number of times Nωd that the rotation direction ωd of the drive wheels has reversed based on the time series data stored in the ring buffer RB2.

[0028] When the conditions X1 to X3 are satisfied, the ECU 10 determines that the condition X is satisfied. In this case, the ECU 10 restricts (prohibits) the execution of the traction control.

[0029] Next, referring to Figure 2, we will explain the program PR1 that the CPU 10a (hereinafter simply referred to as "CPU") executes to realize the above-mentioned cancellation function. The CPU executes the program PR1 every time an infinitesimal time Δt elapses. The CPU starts executing the program PR1 from step 100 and proceeds to step 101.

[0030] 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), the CPU 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), the CPU proceeds to step 105.

[0031] In step 102, the CPU determines whether the average value of the rate of change Δds of the clutch plate clearance Δd within a predetermined period T exceeds a threshold value Δdsth. If the CPU determines that the average value of the rate of change Δds exceeds the threshold value Δdsth (102: Yes), the CPU 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 value Δdsth (102: No), the CPU proceeds to step 105.

[0032] In step 103, the CPU determines whether the number of times Nωd the rotation direction of the drive wheels is switched within a predetermined period T exceeds the threshold value Nωdth. If the CPU determines that the number of times Nωd the rotation direction of the drive wheels is switched within the predetermined period T exceeds the threshold value Nωdth (103: Yes), the CPU proceeds to step 104. On the other hand, if the CPU does not determine that the number of times Nωd the rotation direction of the drive wheels is switched within the predetermined period T exceeds the threshold value Nωdth (103: No), the CPU proceeds to step 105.

[0033] The CPU prohibits the execution of traction control in step 104. The CPU also permits the execution of traction control in step 105. Next, the CPU proceeds to step 106, where it ends the execution of program PR1.

[0034] (Effect) When the rate of change of the clutch plate gap Δd when the clutch is engaged is relatively large and the rotation direction ωd of the drive wheels is repeatedly reversed within the engine, it is highly likely that the driver is performing a driving operation to get the vehicle out of the mud. According to the vehicle control device 1, when the vehicle becomes stuck in the mud, the intervention of automatic control (execution of traction control) in the driving operation to get the vehicle out of the mud is limited.

[0035] (Modification) In the above embodiment, the ECU 10 acquires the rotation direction ωd of the drive wheels from the wheel speed sensor 22 and calculates the number of times Nωd the rotation direction is switched based on the rotation direction ωd. Alternatively, the ECU 10 may calculate the number of times Nωd the rotation direction of the drive wheels is switched based on the shift position of the transmission and the depression depth of the accelerator pedal.

[0036] (Modification 2) The ECU 10 may determine whether the condition X is met, regardless of the position of the mode selection switch 25 (the setting state of the transfer case). That is, the ECU 10 may determine that the condition X is met when the conditions X2 and X3 are met. [Explanation of symbols]

[0037] 1... vehicle control device, 10... ECU, 20... on-vehicle sensor, 30... drive device

Claims

[Claim 1] A vehicle control device including a processor capable of executing traction control that controls a drive device of a host vehicle so that an output of the drive device is reduced when a predetermined condition is met, The processor is configured to not execute the traction control when the rate of change of the distance between the drive shaft side and the driven shaft side of the clutch of the vehicle when the clutch is engaged within a specified period of time exceeds a threshold value, and further when the number of times the direction of rotation of the drive wheels of the vehicle is changed within the specified period of time exceeds a threshold value.

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