Vehicle traction control device

Abstract

To provide a traction control device which dispenses with a switching operation by a switch, can properly detect the stuck state in the time of stuck, has the excellent escape property and is advantageous regarding a manufacturing cost.SOLUTION: A traction control device suppresses idling of drive wheels with the first engine control that performs torque down of an engine when a slip amount of the drive wheels excesses a prescribed threshold and / or the first brake control that actuates braking of the drive wheels whose slip amount excesses the prescribed threshold to increase the torque distribution of other drive wheels. The traction control device determines a stuck state (120) when a prescribed times elapses with zero vehicle speed (110;YES) during the operation of the first engine control or the first brake control (100;YES), and shifts to the second engine control with the smaller torque down amount than that of the first engine control and to the second brake control with the larger brake force than that of the first brake control (130).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a traction control device for a vehicle, and more particularly to a traction control system having a stuck escape function. [Background technology]

[0002] To prevent the drive wheels from spinning when the vehicle is accelerating or traveling on a low-mu road surface, a traction control is known that reduces the drive force and activates the brake device when slippage of the drive wheels is detected to control the amount of slip within a predetermined range (for example, Patent Document 1).

[0003] In addition, in vehicles without a mechanical differential limiting device, if one of the left or right drive wheels spins while driving on rough terrain or snowy roads, the drive force is no longer distributed to the other drive wheels, and the vehicle may become stuck. In such cases, a brake LSD control system is known in which the driver operates a switch to increase the braking force on the idle wheel and concentrate the drive force on the other drive wheels.

[0004] However, in addition to the inconvenience of operating the switch while driving on rough terrain, installing a switch that is only to be used in emergencies is not only disadvantageous in terms of manufacturing costs, but also poses challenges for drivers who are not familiar with the location and function of the switch to operate it in a timely manner. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-90141 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in consideration of the above points, and its purpose is to provide a traction control device that does not require switching operations using a switch, can properly detect a stuck state when stuck, has excellent escape capabilities, and is advantageous in terms of manufacturing costs. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides: A traction control device for a vehicle including an engine, a wheel speed sensor that detects the rotation speed of each wheel, and a brake device that can control the braking force of each wheel, A system that suppresses spin of the drive wheels by a first engine control that calculates the amount of slip from the rotational speed of the wheels and reduces the torque of the engine when the amount of slip of the drive wheels exceeds a predetermined threshold, and / or a first brake control that activates the brake of the drive wheel whose amount of slip exceeds a predetermined threshold to increase the torque distribution of the other drive wheels, The system is characterized in that it is configured to determine that the vehicle is stuck if a predetermined time has elapsed at zero vehicle speed while the first engine control or the first brake control is in operation, and to transition to a second engine control in which the torque reduction amount is smaller than that of the first engine control, and a second brake control in which the braking force is greater than that of the first brake control. [Effects of the Invention]

[0008] The present invention, with the above-described configuration, has the following effects. When a vehicle becomes stuck, the vehicle's system can properly detect the stuck state and transition to stuck-free control, which is advantageous in improving stuck-free escape performance. Furthermore, there is no need to operate a switch to change the driving position, so there is no need to bother with operating a switch while driving on rough terrain, and even drivers who are not familiar with the location and function of the switches can make the system's judgment and execute appropriate control. Furthermore, there is no need to install a changeover switch that is used only in emergencies, which is also advantageous in terms of reducing manufacturing costs. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram illustrating a vehicle in which a traction control device is implemented. [Figure 2] 3 is a flowchart showing control according to the first embodiment of the present invention. [Figure 3] 10 is a flowchart showing a control according to a second embodiment of the present invention. [Figure 4] 10 is a flowchart showing a control according to a third embodiment of the present invention. [Figure 5] 3 is a control map showing the relationship between the amount of slip and the amount of braking. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a schematic configuration of a vehicle in which a traction control device is implemented. In FIG. 1, the vehicle is an internal combustion engine vehicle equipped with an internal combustion engine 1, and is equipped with an engine controller 10 that controls engine 1 based on input signals from sensors that detect the accelerator opening detected by an accelerator opening sensor 11 and various state values ​​that reflect the operating state of the engine, and the driving torque of engine 1 is transmitted to wheels 4 (drive wheels) via a drive train (not shown).

[0011] Each wheel 4 is provided with a brake 2, and each brake 2 is connected via hydraulic piping to a brake control device 20. The brake control device 20 includes a brake operation unit including a brake pedal, a brake booster, a master cylinder, etc. (not shown), a brake actuator that controls hydraulic pressure, and a brake controller.

[0012] The brake actuator is composed of a pump that generates hydraulic pressure for brake control, a motor that drives the pump, a valve that switches from the hydraulic system for brake operation to the hydraulic system for traction control, and other components, and together with the brake controller, forms a traction control system.

[0013] The brake controller is a microcomputer that calculates the amount of slip from the deviation of the detected values ​​of the wheel speed sensors 24 that detect the rotational speed of each wheel 4, and executes traction control (brake TCS) that activates the brakes 2 of the slipping wheels 4 (drive wheels), and traction control (engine TCS) that suppresses the torque of the engine 1 via the engine controller 10, and is composed of a CPU, ROM, RAM, input / output interface, etc.

[0014] The traction control system is implemented in a brake controller (20) as part of the function of an electronic stability control system (ESC), which includes an anti-lock brake control (ABS) that prevents locking during braking. The brake controller (20) is interconnected with the engine controller 10.

[0015] The engine controller 10 calculates the target torque from the torque required by the driver (accelerator opening) and the torque required based on traction control (engine TCS), controls the engine output by adjusting the throttle opening and controlling the ignition timing (retard control), and reduces the driving torque to perform traction control (engine TCS).

[0016] As already mentioned, when one of the left or right drive wheels spins while traveling on rough terrain or snowy roads, the drive force is no longer distributed to the other drive wheels, and the vehicle may become stuck. Therefore, the traction control device according to the present invention detects this stuck state on the vehicle side, and switches to stuck escape control, which increases the braking force of the idling wheel in the traction control (brake TCS) and concentrates the drive force on the other drive wheels.

[0017] When a vehicle becomes stuck on rough terrain or a snowy road, it means that one of the traction controls (engine TCS or brake TCS) has been operating (at least simultaneously) before the vehicle becomes stuck, and the vehicle is essentially stopped in that state, i.e., the vehicle speed is 0 km / h. Therefore, in consideration of the stability of control, the traction control device according to the present invention determines that the vehicle is stuck if the vehicle speed remains at 0 km / h for a predetermined period of time (for example, 1 second) while one of the traction controls (engine TCS or brake TCS) is operating.

[0018] For example, in the case of a two-wheel drive, if the average wheel speed of the driven wheels is zero or if the wheel speed of any of the drive wheels is zero, the vehicle speed can be estimated to be zero. In the case of a four-wheel drive, although it is less likely to become stuck than in a two-wheel drive, if diagonally opposite wheels (for example, the right front wheel and the left rear wheel) lose traction, the vehicle will become stuck, so if the wheel speed of any of the drive wheels is zero, the vehicle speed can be estimated to be zero.

[0019] (First embodiment) Fig. 2 is a flowchart corresponding to the control in the first embodiment of the present invention. In Fig. 2, during operation of traction control (engine TCS or brake TCS) (step 100; YES), if the vehicle speed detected by the wheel speed sensor 24 is zero for a predetermined time (e.g., one second) (step 110; YES), and it is determined that the vehicle is stuck (step 120), the process proceeds to the following stuck escape control (step 130).

[0020] That is, (i) In the brake TCS, the brake amount of the drive wheels 4 (idling wheels) for which the detection value of the wheel speed sensor 24 is not zero is increased (second brake control), and (ii) The amount of torque reduction in the engine TCS is reduced (second engine control).

[0021] The above (i) suppresses the rotation (idling) of the idling wheel, and torque is transmitted to the other driving wheels (non-idling wheels) via the differential device, so that the driving force (propulsion force) of the non-idling wheels promotes escape from the stuck state, and the above (ii) relatively increases the driving force of the non-idling wheels, further promoting escape from the stuck state.

[0022] When the vehicle is released from the stuck state, the wheel speeds of the non-idling wheels are detected by the wheel speed sensors 24, and the estimated vehicle speed is detected by averaging the detected values ​​of the wheel speed sensors 24. However, if the above-described stuck-vehicle release control is immediately terminated and normal traction control is resumed when the vehicle speed is still low immediately after release, there is a risk that the vehicle will become stuck again due to the relative decrease in braking force and torque reduction.

[0023] Therefore, when the vehicle speed is estimated to be equal to or greater than a predetermined value (e.g., 15 km / h) that indicates that the vehicle is in a sufficiently powerful driving state (step 140; YES), the stuck escape control is terminated and normal traction control is resumed (step 150), thereby stabilizing the control.

[0024] In addition, the determination to escape from a stuck state is made by terminating the stuck escape control when a vehicle speed equal to or greater than a predetermined value (e.g., 15 km / h) as described above is detected, or when a vehicle speed equal to or greater than a second predetermined value (e.g., 5 to 10 km / h) smaller than the above predetermined value is detected for a predetermined period of time (e.g., 1 to 2 seconds).This stabilizes the control and minimizes driving under stuck escape control.

[0025] The traction control including the stuck vehicle escape function as described above may be configured to perform stuck determination at all times while the vehicle is traveling and traction control is operating, provided that a traveling mode including the stuck vehicle escape function has been selected in advance, and to terminate the control and transition to a traveling mode that does not include the stuck vehicle escape function when the driver turns off the traveling mode changeover switch (not shown) (step 160; YES) due to the end of rough terrain traveling, for example.

[0026] Furthermore, in the above (i), when the braking amount in the brake TCS is increased, as shown in FIG. 5, the slip amount threshold s1 at which control is started is changed to a smaller threshold s2, the braking amount p1 at the start of control is changed to a larger braking amount p2, and the rate of increase of the braking amount P2 with an increase in the slip amount is increased, thereby making it possible to start braking control earlier and generate a large braking force as needed.

[0027] (Second embodiment) Next, FIG. 3 is a flowchart corresponding to the control in the second embodiment of the present invention. The same reference numerals are used to designate the same components as in the first embodiment, and the description will be omitted. The following description will focus on the changes.

[0028] First, in the second embodiment shown in Figure 3, when traction control (engine TCS or brake TCS) is operating (step 100; YES), if the accelerator opening detected by the accelerator opening sensor 11 is equal to or greater than a predetermined threshold (step 102; YES), and if the detection value of the wheel speed sensor 24 detects a vehicle speed of zero continuously for a predetermined time (e.g., 1 second) (step 110; YES), and if it is determined from the image of the camera 3 that the vehicle is in a stopped state (step 114; YES), then it is determined that the vehicle is stuck.

[0029] By adding a condition to the stuck state determination that the accelerator opening is equal to or greater than a predetermined threshold (for example, 70% or greater) that reflects the driver's intention to accelerate, stuck state escape control is postponed if the driver does not intend to accelerate, for example, if the driver releases the accelerator to avoid being stuck, and stuck state escape control is postponed, giving priority to the escape attempt by the driver's operation, while switching to stuck state escape control when the accelerator is operated with sufficient intention, has the advantage of ensuring that the required torque is distributed to the non-idling wheels.

[0030] Furthermore, by adding stop determination based on images from camera 3 to stuck determination, it becomes possible to more accurately detect zero vehicle speed. Image processing means 30 built into or connected to camera 3 is configured as a microcomputer equipped with VRAM that dynamically records images captured by camera 3, ROM that stores image processing algorithms, a CPU that executes processing, and an input / output interface.

[0031] As the image processing algorithm, for example, an image processing algorithm that extracts the optical flow of feature points from a time series of field of view images (field of view video) captured at a predetermined frame rate can be used. That is, the feature point extraction process is executed for each image frame, and the optical flow is extracted as the movement trajectory of corresponding feature points between successive image frames. When the vehicle is traveling forward, the road and surrounding stationary objects are detected as optical flows moving away from a vanishing point if the camera 3 is a front camera, and are detected as optical flows moving toward the vanishing point if the camera 3 is a rear camera. However, when the vehicle is stopped, the optical flows of the road and surrounding stationary objects disappear, so that it is possible to quickly and reliably determine whether the vehicle is stuck.

[0032] In addition to the above, the image processing means 30 for detecting the vehicle's stopped state may also extract the difference between each image frame and the previous frame, and determine that the vehicle is stopped when the amount of data of the difference can be considered to be substantially zero.

[0033] In the second embodiment shown in FIG. 3, in addition to determining whether the vehicle is free from stuck state based on the vehicle speed after transitioning to stuck state elimination control (step 140), if the vehicle speed does not reach a predetermined threshold (step 140; NO) and a predetermined time (e.g., 2 to 5 seconds) or more has elapsed since the start of stuck state elimination control (step 143; YES), TCS engine control (engine TCS) is prohibited (step 144).

[0034] When switching to stuck vehicle escape control, the amount of torque reduction in the TCS engine control (engine TCS) is changed to a smaller value, and a relatively large driving torque is output. However, if the vehicle is unable to escape from the stuck state after a predetermined time has elapsed, the TCS engine control (engine TCS) itself is prohibited, and torque reduction is not performed, which allows a greater driving force to be transmitted to the non-idling wheels, which has the advantage of enabling a more effective escape from the stuck state.

[0035] (Third embodiment) Next, FIG. 4 is a flowchart corresponding to the control in the third embodiment of the present invention. The same reference numerals are used to designate the same components as those in the first and second embodiments described above, and the following description will focus on the changes.

[0036] In the third embodiment shown in FIG. 4, if it is determined in steps 100 to 114 that the vehicle is stuck, it is checked whether the load on the vehicle is equal to or greater than a predetermined amount (step 126), and different processing is executed depending on the result.

[0037] The traction control device of the present invention is also envisioned for implementation in light trucks and the like that often travel on rough terrain such as farmland, civil engineering work sites, etc. In such vehicles, when there is a significant load compared to when the load is light or empty, that is, when the vehicle load is equal to or greater than a predetermined amount (step 126; YES), the TCS engine control that is executed simultaneously with the TCS brake control is immediately prohibited (step 131), and a relatively large driving force is transmitted to the non-idling wheels, which is expected to enable more effective escape from a stuck situation.

[0038] On the other hand, if the vehicle load is less than a predetermined amount (step 126; NO), first, TCS brake control is executed to increase the amount of braking on the idle wheels, and at the same time, TCS engine control is executed to reduce the amount of torque down (step 132). Only if the stuck state cannot be escaped after a predetermined time has elapsed (step 142; NO, step 143; YES), is TCS engine control prohibited (step 144).

[0039] Whether the load is equal to or greater than a predetermined amount (whether the vehicle is substantially unladen) can be determined, for example, based on the image of the camera 3. That is, by carrying out calibration in advance on a flat road to determine the coordinates (heights) of the vanishing points of the optical flow when the vehicle is unladen and when the vehicle is loaded with a load equal to or greater than a predetermined amount, the image processing means 30 can make a determination by comparing the images obtained with those of the camera 3 while the vehicle is traveling.

[0040] Furthermore, since the loading platform (rear wheel side) of a loaded vehicle lowers and the angle of view of the camera 3 rises, it is also possible to make a determination based on the angle of view of the image from the camera 3. Furthermore, in addition to using the camera 3, it is also possible to detect based on the measured value of the suspension stroke or the loaded weight, or to configure it so that the driver can set it in advance.

[0041] Although several embodiments of the present invention have been described above, it should be noted that the present invention is not limited to the above-described embodiments, and various modifications and variations are possible based on the technical concept of the present invention. [Explanation of symbols]

[0042] 1 engine 2 Brake device 3 Camera 4 wheels (drive wheels) 10 Engine Controller 11 Accelerator opening sensor 20 Brake control device 24 Wheel speed sensor 30 Image processing means

Claims

1. A traction control device for a vehicle including an engine, a wheel speed sensor that detects the rotation speed of each wheel, and a brake device that can control the braking force of each wheel, A system that suppresses spin of the drive wheels by a first engine control that calculates a slip amount from the rotation speed of the wheels and reduces the torque of the engine when the slip amount of the drive wheels exceeds a predetermined threshold, and / or a first brake control that activates the brake of the drive wheel whose slip amount exceeds a predetermined threshold to increase the torque distribution of the other drive wheels, A traction control device for a vehicle, characterized in that it is configured to determine that the vehicle is stuck if a predetermined time has elapsed at zero vehicle speed while the first engine control or the first brake control is in operation, and to transition to a second engine control in which the torque reduction amount is smaller than that of the first engine control, and a second brake control in which the braking force is greater than that of the first brake control.

2. 2. A traction control device for a vehicle according to claim 1, wherein the predetermined threshold value of the slip amount is changed to a second predetermined threshold value that is smaller than the predetermined threshold value when the stuck state is determined.

3. 2. A traction control device for a vehicle according to claim 1, wherein the vehicle is configured to determine that it is stuck when the accelerator opening is equal to or greater than a predetermined value that reflects the driver's intention to accelerate and the vehicle speed is zero for a predetermined time while the first engine control or the first brake control is in operation.

4. 4. The traction control device for a vehicle according to claim 1, wherein the vehicle comprises a camera for capturing an image of the outside world, and an image processing means for detecting zero vehicle speed from an image captured by the camera.

5. A traction control device for a vehicle as described in any one of claims 1 to 4, characterized in that if the vehicle speed becomes equal to or higher than a first predetermined speed after transitioning to the second engine control and the second brake control, or if the vehicle speed remains equal to or higher than a second predetermined speed that is lower than the first predetermined speed for a predetermined time, it is determined that the vehicle has escaped from the stuck state and the second engine control and the second brake control are terminated.

6. A traction control device for a vehicle as claimed in any one of claims 1 to 5, characterized in that if the second engine control and the second brake control are continued even after a predetermined time has elapsed since the transition to the second engine control and the second brake control, torque reduction control of the engine is prohibited.

7. The traction control device for a vehicle according to any one of claims 1 to 6, characterized in that the vehicle is provided with a load state determination means for determining a load state, and is configured to prohibit torque reduction control of the engine when transitioning to the second brake control if the load amount is equal to or greater than a predetermined amount.

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