Vehicle behavior control device

Abstract

This vehicle-behavior control device causes brake devices on the respective wheels of a vehicle to operate and generate an individual braking force for each wheel, thereby determining, while brake control that realizes vehicle braking according to a prescribed total braking force is underway, whether any wheel is in an unweighted state in which traction load thereon is lost, on the basis of the operational state of the vehicle. With respect to braking-force shortage, which is the individual braking force on a wheel that has been determined to be in the unweighted state, the vehicle-behavior control device adds a brake-device operational amount corresponding to a portion or the entirety of the braking-force shortage as the operational amount of any one or more of the brake devices corresponding to the wheels that have not been determined to be in the unweighted state.

Description

[Technical Field]

[0001] The present disclosure relates to a vehicle behavior control device that controls the behavior of a vehicle by operating brake devices corresponding to each wheel. [Background technology]

[0002] In recent years, vehicles have become known that are configured to be able to perform brake control, such as braking the vehicle with a predetermined total braking force by operating brake devices corresponding to each wheel (see Patent Document 1). This brake control can assist the vehicle in traveling on steep or slippery slopes while maintaining a predetermined total braking force. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2012-206679 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the above configuration, there is a concern that depending on road surface conditions, some wheels may come off the road surface, resulting in a loss of ground load, and the total braking force required by the above-mentioned brake control may not be maintained, resulting in a significant decrease in braking force. Such a decrease in braking force is undesirable because it can cause problems such as giving the occupants a feeling of freewheeling, unintended speed fluctuations, and wheel slippage.

[0005] The present disclosure has been made to solve such problems, and its purpose is to suppress problems caused by a significant decrease in braking force during brake control. [Means for solving the problem]

[0006] The vehicle behavior control device of the present disclosure includes a load-release determination means for determining whether the ground load of each wheel is released and in a load-release state based on the operating state of the vehicle during brake control that operates the brake devices of each wheel of the vehicle and generates individual braking forces for each wheel, thereby braking the vehicle with a predetermined total braking force, and an operation addition means for adding, for an insufficient braking force, which is the individual braking force of a wheel that has been determined to be in the load-release state, an operation amount of the brake device corresponding to part or all of the insufficient braking force as an operation amount of one or more of the brake devices corresponding to the wheels that have not been determined to be in the load-release state.

[0007] According to this vehicle behavior control system, when some wheels are unloaded, an operating amount corresponding to part or all of the insufficient braking force is applied to the brake devices corresponding to the other wheels to generate additional individual braking force. In this way, the insufficient braking force caused by the unloaded wheel is compensated for by the other wheels, so the total braking force required by the brake control is not significantly reduced. As a result, problems such as a feeling of freewheeling to the occupants and unintended speed fluctuations and wheel slippage can be suppressed. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide a vehicle behavior control device that can suppress the occurrence of problems caused by the total braking force not being maintained during brake control. [Brief explanation of the drawings]

[0009] [Figure 1] A block diagram showing the overall configuration of a vehicle according to the present disclosure. [Figure 2] Flowchart showing the procedure for action addition processing DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0011] (1) Overall structure As shown in FIG. 1, the vehicle 1 is equipped with a plurality of wheels 10, a brake device 20 provided on each wheel 10, a drive device 30 that drives each brake device 20, a suspension device 40 that suspends each wheel 10 from the vehicle 1 body, a stroke sensor 50 provided next to each suspension device 40, an acceleration sensor 60 that detects the acceleration of the vehicle 1, a vehicle speed sensor 70 that detects the speed of the vehicle 1, and a vehicle behavior control device 80 which is an ECU (Electronic Control Unit) that controls the operation of the entire vehicle 1.

[0012] In this embodiment, the vehicle 1 is illustrated as having a pair of wheels 10 arranged on the left and right sides at the front and a pair of wheels 10 arranged on the left and right sides at the rear.

[0013] The drive unit 30 operates each of the brake devices 20 upon receiving a command from the vehicle behavior control device 80. In this embodiment, the brake devices 20 and the drive unit 30 are directly or indirectly connected by hydraulic paths, and the drive unit 30, upon receiving a command from the vehicle behavior control device 80, applies the necessary hydraulic pressure to each of the brake devices 20 to generate a predetermined braking force on each wheel 10 in accordance with the command.

[0014] The stroke sensor 50 is a sensor that detects the stroke amount of a shock absorber (not shown) that is interposed between the vehicle 1 body and the wheel 10 in the suspension device 40.

[0015] The acceleration sensor 60 is composed of a sensor that detects acceleration in the front-rear direction of the vehicle 1 and a sensor that detects acceleration in the left-right direction.

[0016] (2) Action addition processing by the vehicle behavior control device 80 Next, the action addition process performed by the vehicle behavior control device 80 will be described with reference to Fig. 2. This action addition process is a process that the vehicle behavior control device 80 executes in accordance with a program stored in the built-in memory 71, and is activated on the condition that a brake control process similarly executed in accordance with a program has been activated.

[0017] This brake control process is a process for brake control in which the drive unit 30 generates individual braking forces for each wheel 10, thereby braking the vehicle 1 with a predetermined total braking force. In this embodiment, an example of the brake control is a configuration in which hill descent control (HDC) is implemented, which supports the vehicle 1 traveling forward on a steep or slippery slope while maintaining a predetermined total braking force.

[0018] When this action addition process is started, first, the speed of the vehicle 1 detected by the vehicle speed sensor 70 is equal to or greater than a predetermined speed (30 km / h in this embodiment). under The process waits until the condition is met (s110: NO).

[0019] In this s110, the speed is greater than the specified speed. under If this is the case (s110: YES), it is checked whether or not each wheel 10 is in a weight-relieved state, where the ground contact load is released, based on the operating state of the vehicle 1 (s120). Here, the stroke amount detected by each stroke sensor 50 is checked, and for the stroke sensor 50 that indicates the stroke amount reached when the wheel 10 is off the ground, it is determined that the corresponding wheel 10 is in a weight-relieved state.

[0020] In addition, in step S120, it may be determined that the wheels 10 whose ground load has become small to some extent are in the unloaded state in addition to the detection value of the stroke sensor 50. In this case, the ground load of each wheel 10 may be estimated based on the specifications of the vehicle 1 such as the wheelbase and the height of the center of gravity, the vehicle body tilt angle calculated from the detection value of the acceleration sensor 60, the friction coefficient of the road surface, etc., and the ground load may be determined to be unloaded when it is equal to or less than a predetermined threshold value.

[0021] In step s120, if it is determined that none of the wheels 10 is in the unloaded state (step s120: NO), the process returns to step s110.

[0022] On the other hand, if it is determined in s120 that at least one of the wheels 10 is in a weight-released state (s120: YES), the braking force that is insufficient due to the wheels 10 determined to be in a weight-released state (insufficient braking force) is calculated (s130). Here, the insufficient braking force is calculated as the sum of the individual braking forces that have been generated in the individual wheels 10 in the brake control for the wheels 10 determined to be in a weight-released state.

[0023] In addition, when the individual braking forces generated on each wheel 10 during brake control are the same (including within a predetermined threshold range), the insufficient braking force may be calculated based on "(number of wheels 10 determined to be in a weight-released state x individual braking force) / number of wheels 10 not determined to be in a weight-released state."

[0024] Next, the ground load of each wheel 10 is detected (s140). Here, the ground load is detected as an estimated value calculated based on the specifications of the vehicle 1 such as the wheelbase and the height of the center of gravity, the vehicle body tilt angle calculated from the detection value of the acceleration sensor 60, the friction coefficient of the road surface, and the like.

[0025] Next, an individual braking force required for each wheel 10 to additionally generate the insufficient braking force calculated in s130 is set (s150). Here, for each wheel 10 that is not determined to be in a weight-relieved state, a larger individual braking force is set for the wheel 10 with a larger ground contact load, the wheel 10 that is located further forward, and in accordance with the positional relationship with the wheel 10 in a weight-relieved state.

[0026] In this embodiment, the sum of a first coefficient according to the ground load, a second coefficient according to whether the ground load is front or rear, and a third coefficient according to the positional relationship with the wheel 10 in the unloaded state is calculated for each wheel 10, and the individual braking force is set according to the ratio of these sums. Here, the first coefficient is set to a larger value for a wheel 10 with a larger ground load detected in s130. The second coefficient is set to a larger value for the wheel 10 at the front in the traveling direction (at the front of the vehicle 1 in this embodiment) than for the wheel 10 at the rear. The third coefficient is set to a larger value for the wheel 10 located on the same left and right side of the pair of wheels 10 opposite each other in the front-to-back direction that is determined to be in the unloaded state than for the other wheels 10.

[0027] In addition, if the wheels 10 that are not determined to be in a weight-released state include both the left and right wheels 10 that make up a pair, the value of at least one of the individual braking forces is adjusted so that the difference between the individual braking forces of the left and right wheels 10 is equal to or less than a predetermined threshold value.

[0028] Then, a command is sent to the drive unit 30 to generate additional braking force to compensate for the insufficient braking force for each wheel 10 that has not been determined to be in a weight-released state (s160). Here, each brake unit 20 is commanded via the drive unit 30 to operate at the amount of operation required to generate the additional individual braking force set in s150, and the brake unit 20 that has received this command generates the additional individual braking force.

[0029] As a result, the operation amount of the brake device 20 corresponding to part or all of the insufficient braking force is added as an additional operation amount of one or more of the brake devices 20 corresponding to the wheels 10 that are not determined to be in the unloaded state. After s160, the process returns to s110.

[0030] In the action addition process described above, s110 is the vehicle speed detection means, s120 is the weight release determination means, s140 is the load detection means, and s160 is the action addition means.

[0031] Although the embodiments of the present disclosure have been described above, it goes without saying that the present disclosure is not limited to the above embodiments and can take various forms as long as they fall within the technical scope of the present disclosure.

[0032] (3) Effects According to the vehicle behavior control device 80 of the above embodiment, when some of the wheels 10 are in a non-weighted state, an operation amount corresponding to part or all of the insufficient braking force can be applied to the brake devices 20 corresponding to the other wheels 10 to generate additional individual braking force. In this way, the insufficient braking force due to the non-weighted wheel 10 is compensated for by the other wheels 10, so that the total braking force required by the brake control is not significantly reduced. As a result, it is possible to suppress problems such as giving the occupants a feeling of freewheeling, unintended speed fluctuations, and wheel 10 slippage.

[0033] Furthermore, in the vehicle behavior control device 80, when applying an operation amount corresponding to the insufficient braking force to the brake device 20, the larger the ground load of a wheel 10, the larger the operation amount is applied to the brake device 20 corresponding to that wheel 10, thereby generating an additional individual braking force (s150 in FIG. 2). As a result, an unnecessarily large operation amount of the brake device 20 is not allocated to a wheel 10 with a small ground load, and as a result, it is possible to prevent the wheel 10 from locking due to the allocation of the operation amount, and ultimately prevent the locked wheel from slipping.

[0034] Furthermore, in the vehicle behavior control device 80, when applying an operation amount corresponding to the insufficient braking force to the brake devices 20, a larger operation amount is applied to the brake devices 20 corresponding to the wheels 10 that are located further forward in the traveling direction of the vehicle 1, thereby generating additional individual braking force (s150 in FIG. 2). When braking the vehicle 1, inertia comes into play, and the ground contact load tends to be larger for the wheels 10 that are further forward in the traveling direction. Therefore, in this embodiment, an unnecessarily large operation amount of the brake devices 20 is not allocated to wheels 10 with a small ground contact load, and as a result, it is possible to prevent the wheels 10 from locking due to the allocation of the operation amount, and ultimately prevent the locked wheels 10 from slipping.

[0035] Furthermore, the vehicle behavior control device 80 adjusts the operation amount of the brake device 20 within a range in which the difference in the individual braking forces generated by the paired left and right wheels 10 is equal to or less than a predetermined threshold value (s150 in FIG. 2). If the difference in the individual braking forces generated by the paired left and right wheels 10 becomes large, problems such as unintended turning of the vehicle 1 or differential locking of the differential device may occur. In this regard, in this embodiment, by setting an appropriate threshold value, the occurrence of the above problems can be prevented.

[0036] Furthermore, the vehicle behavior control device 80 can apply a larger amount of operation to the brake devices 20 of the wheels 10 located on the same left and right sides of the pair of wheels 10 determined to be in a weight-released state than to the other brake devices 20, thereby generating an additional individual braking force (s150 in FIG. 2).This makes it possible to generate another yaw moment in a direction that cancels out the yaw moment caused by the wheel 10 in a weight-released state.

[0037] Furthermore, the vehicle behavior control device 80 can determine whether the wheels 10 are in a weight-relieving state and generate additional individual braking forces when the vehicle speed is equal to or lower than a predetermined speed.

[0038] Although various embodiments have been described above, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above embodiments may be combined in any manner as long as they do not deviate from the spirit of the invention.

[0039] This application is based on a Japanese patent application (Patent Application No. 2022-031532) filed on March 2, 2022, the contents of which are incorporated herein by reference. [Explanation of symbols]

[0040] 1...vehicle, 10...wheel, 20...brake device, 30...drive device, 40...suspension device, 50...stroke sensor, 60...acceleration sensor, 70...vehicle speed sensor, 71...built-in memory, 80...vehicle behavior control device

Claims

1. a load-release determination means for determining whether or not the ground load of each wheel is released based on the operating state of the vehicle during brake control that operates the brake devices of each wheel of the vehicle to generate individual braking forces for each wheel and thereby brake the vehicle with a predetermined total braking force; an operation adding means for adding an operation amount of a brake device corresponding to a part or all of the insufficient braking force, which is an individual braking force of a wheel determined to be in the unloaded state, as an operation amount of one or more of the brake devices corresponding to the wheels not determined to be in the unloaded state; a load detection means for detecting a ground load of each wheel; Equipped with The vehicle behavior control device is configured such that the greater the ground load detected by the load detection means for a wheel, the higher the proportion of the amount of operation applied to the brake device of that wheel.

2. a load-release determination means for determining whether or not the ground load of each wheel is released based on the operating state of the vehicle during brake control that operates the brake devices of each wheel of the vehicle to generate individual braking forces for each wheel and thereby brake the vehicle with a predetermined total braking force; an operation adding means for adding an operation amount of a brake device corresponding to a part or all of the insufficient braking force, which is an individual braking force of a wheel determined to be in the unloaded state, as an operation amount of one or more of the brake devices corresponding to the wheels not determined to be in the unloaded state; Equipped with The vehicle behavior control device is configured such that the operation adding means increases the proportion of the amount of operation added to the brake device of a wheel disposed further forward in the traveling direction of the vehicle.

3. a load-release determination means for determining whether or not the ground load of each wheel is released based on the operating state of the vehicle during brake control that operates the brake devices of each wheel of the vehicle to generate individual braking forces for each wheel and thereby brake the vehicle with a predetermined total braking force; an operation adding means for adding an operation amount of a brake device corresponding to a part or all of the insufficient braking force, which is an individual braking force of a wheel determined to be in the unloaded state, as an operation amount of one or more of the brake devices corresponding to the wheels not determined to be in the unloaded state; Equipped with In the case where the vehicle has a pair of wheels arranged on the left and right sides at the front and a pair of wheels arranged on the left and right sides at the rear, The operation addition means increases the proportion of the amount of operation added to the brake devices of the wheels located on the same left and right sides of the pair of wheels opposite each other in the front and rear direction that are determined to be in the unloaded state, compared to the other brake devices.

4. In the case where the vehicle has a pair of wheels arranged on the left and right, the operation adding means adds an amount of operation within a range in which the difference between the individual braking forces generated by the pair of left and right wheels is equal to or less than a predetermined threshold value; The vehicle behavior control device according to any one of claims 1 to 3.

5. A vehicle speed detection means for detecting a vehicle speed is provided, the determination by the unloading determination means and the addition of the operation amount by the operation addition means are performed when the vehicle speed detected by the vehicle speed detection means is equal to or lower than a predetermined speed; The vehicle behavior control device according to any one of claims 1 to 3.

6. In the case where the shock absorber of the suspension device corresponding to each wheel is equipped with a stroke sensor that detects the stroke amount, the unloading determination means determines that the wheel corresponding to the stroke sensor is in the unloaded state when the stroke amount detected by the stroke sensor is the stroke amount reached when the wheel is off the ground. The vehicle behavior control device according to any one of claims 1 to 3.

7. a load detection means for detecting a ground load of each wheel; The unloading determination means determines that the wheel bearing the ground load detected by the load detection means is in the unloading state when the ground load detected by the load detection means is equal to or less than a predetermined threshold value. The vehicle behavior control device according to any one of claims 1 to 3.

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