JP2003081077A - Wheel brake control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a wheel to be less easily locked without increasing any braking time or a braking distance. SOLUTION: A wheel brake control device comprises a brake disk 4 and main and sub brake mechanisms 20 and 40, a wheel speed sensor 64 and a control device 68. The disk 4 is rotated integrally with a wheel 3, and the main and sub brake mechanisms 20 and 40 brake the wheel 3 by pressing main and sub pads 6 and 8 against the disk 4 according to the operation of a brake pedal 1. The control device 68 detects a state immediately before locking the wheel 3 or an initial state of the wheel based on the detection result of the wheel speed sensor 64, and temporarily reduces the pressure of the main pad 6 in the main brake mechanism 20. The control device 68 repeats the fluctuation cycle that the pressure of the sub pad 8 is once reduced, and then, increased by the sub brake mechanism 40 before detecting the state immediately before locking the wheel or the initial state of the wheel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automobile or the like in which a friction material is brought into pressure contact with a brake disc in response to a brake operation to brake wheels, by changing the pressure contact force of the friction material in accordance with the rotating condition of the wheel. The present invention relates to a wheel brake control device that unlocks a lock.

[0002]

2. Description of the Related Art Conventionally, in automobiles, for example, hydraulic fluid pressure of brake fluid is used to transmit the operation of a brake pedal to a caliper, a friction material (pad) is pressed against a brake disc, and the friction between the two causes the wheels to move. Disc brakes that are adapted to brake are known.

On the other hand, when the vehicle is running on a road surface that is slippery due to rainfall, snowfall, etc. and sudden braking is applied, if the braking force exceeds the frictional force between the road surface and the wheels, the wheels lock ( (While the vehicle body is moving forward, the wheels may stop rotating). When the locked wheel is the front wheel, steering is not effective, and when it is the rear wheel, the posture of the vehicle body becomes unstable.

Therefore, various anti-lock brake devices have been developed and put into practical use, which prevent the wheels from being locked by a braking operation similar to a pumping brake to maintain the steering ability and stabilize the posture of the vehicle body. In this device, for example, when the state immediately before the wheel is locked or the initial state is detected, the hydraulic pressure is temporarily reduced and the pressure contact force of the friction material with the brake disc is reduced. Due to this decrease, the braking force becomes slightly smaller than the frictional force between the road surface and the wheels, and the rotation of the wheels is restored. However, the hydraulic pressure continues to increase and the pressure contact force increases. Then, the cycle of decreasing and increasing the pressure contact force is repeated to unlock the wheels.

[0005]

However, in the conventional antilock brake device, the friction material used for the normal braking operation is also used as the friction material of the device,
Due to the anti-lock brake operation structure, these operations can be performed individually but not both at the same time. Therefore, when the brake pedal is depressed, the normal braking operation is first performed, and when the wheels are in the state immediately before the locking or in the initial state, the antilock braking operation is switched. Therefore, although the lock can be released early, it is difficult to prevent the lock from occurring easily. On the other hand, it is conceivable to accelerate the switching timing. However, since the period of the normal braking operation is shortened accordingly, a new problem arises that the braking time becomes longer and the braking distance becomes longer.

During the antilock brake operation,
Reaction force when the hydraulic pressure of the caliper fluctuates (increases or decreases) is transmitted to the brake pedal (this phenomenon is called kickback),
The pedal vibrates in small steps. At this time, the brake pedal starts to move against the driver's will, which causes the driver to feel uncomfortable. This problem cannot be solved even if the occurrence of kickback is informed by light or sound.

Therefore, an object of the present invention is to provide a brake control device for a wheel that can prevent the locked state of the wheel from occurring without increasing the braking time and the braking distance. Another object of the present invention is to provide a brake control device for a wheel that can prevent kickback from occurring in addition to the above problems.

[0008]

According to a first aspect of the present invention, a brake disc that rotates integrally with a wheel and a main friction material is pressed against the brake disc according to an operation of a brake operating member to brake the wheel. Main braking mechanism, lock detecting means for detecting the state immediately before the wheel is locked or the initial state, and the pressure contact force of the main friction material in the main braking mechanism is temporarily reduced according to the detection result of the lock detecting means. In a wheel brake control device including a main brake control means, a sub-brake mechanism that presses a sub-friction material provided separately from the main friction material onto the brake disc to brake the wheel, and the brake operation member. During the operation, prior to the detection by the lock detecting means, a fluctuation cycle in which the pressure contact force of the auxiliary friction material is reduced and then increased is performed. A first sub-brake control means for repeating the mechanism, and further, in the brake disc, the sub-friction material is arranged adjacent to and independent of a region in which the main friction material is arranged. And the auxiliary friction material are connected to each other.

Therefore, when the brake operating member is operated, the main friction member is brought into pressure contact with the brake disc that rotates integrally with the wheel in the main brake mechanism in response to the operation. The rotation of the wheels is braked by the friction between the brake disc and the main friction material that accompanies this pressure contact. When the braking force at this time exceeds the frictional force between the road surface and the wheels and the state immediately before the lock occurs or the lock initial state is reached,
This is detected by the lock detecting means. In response to this detection, the main brake control means controls the main brake mechanism. By this control, the pressure contact force of the main friction material once decreases and then rises, and the antilock brake operation similar to the pumping brake operation is performed.

While the brake operating member is being operated, the sub-brake mechanism is controlled by the first sub-brake control means before the lock detecting means detects the state immediately before locking or the initial state. That is, before the control of the main brake mechanism is performed by the main brake control means, and during the period in which the main friction material continues to be in pressure contact with the brake disc, the pressure contact force of the sub friction material with respect to the brake disc in the sub brake mechanism The cycle of fluctuations consisting of a decrease and a rise of is repeated. As described above, the braking force associated with the normal braking operation by the main braking mechanism and the braking force associated with the intermittent braking operation by the auxiliary braking mechanism are simultaneously applied to the wheels. This intermittent braking operation can be said to be a kind of pumping braking operation as well as the anti-lock braking operation. As a result, the lock is less likely to occur as compared with the case of only the normal brake operation.
Further, unlike the case where the timing of switching from the normal braking operation to the anti-lock braking operation is simply advanced, a large braking force is applied, so that the braking time and the braking distance do not become long. Further, the friction materials of the main brake mechanism and the sub brake mechanism are arranged adjacent to each other on the brake disc, thereby achieving compactness.

According to a second aspect of the present invention, in the first aspect of the invention, there is further provided a brake operation detecting means for detecting an operation of the brake operating member, and the first sub-brake control means includes the brake operation. The detection of the brake operation by the detection means is used as the start condition of the pressure contact fluctuation cycle.

Therefore, when the operation of the brake operating member is detected by the brake operation detecting means, the first
The sub-brake control means starts a cycle of changing the pressure contact force of the sub-friction material to the brake disc. In this way, the intermittent braking operation by the first sub-brake control means is performed from the beginning of the normal braking operation by the main braking mechanism accompanying the operation of the brake operating member.

The invention described in claim 3 is the invention according to claim 1 or 2.
In the invention described in (1), the first sub-brake control means sets the detection of the immediately preceding state or the initial state of the lock by the lock detection means as the ending condition of the pressure contact variation cycle.

Accordingly, when the lock detecting means detects the state immediately before the wheel is locked or the initial state, the fluctuation cycle by the first sub brake control means is ended. In this way, the intermittent brake operation by the first sub brake control means is performed until the end of the normal brake operation by the main brake mechanism accompanying the operation of the brake operating member.

According to a fourth aspect of the invention, in the invention according to any one of the first to third aspects, after the control of the sub-brake mechanism by the first sub-brake control means is finished, the main brake control means is provided. Prior to the control of the main brake mechanism by the second auxiliary mechanism, the second auxiliary brake mechanism is made to repeatedly decrease and increase the pressure contact force of the auxiliary friction material on condition that the lock detecting means detects the state immediately before the lock or the initial state. Brake control means is further provided.

Therefore, in the period after the control of the sub-brake mechanism by the first sub-brake control means is completed and before the control of the main brake mechanism by the main brake control means is started, the sub-brake mechanism is operated by the second sub-brake mechanism. The brake control means controls as follows. When the lock detection unit detects the state immediately before the wheel is locked or the initial state, the auxiliary brake mechanism raises the pressure contact force of the auxiliary friction material after it is once reduced. The fluctuation cycle consisting of the decrease and increase of the pressure contact force is repeated, and the anti-lock brake operation is performed by the auxiliary brake mechanism. In other words, the anti-lock braking operation by the main braking mechanism is not performed at the same time when the state immediately before the wheel is locked or the initial state is detected, but first, the anti-lock braking operation by the auxiliary braking mechanism is performed, and then the main braking operation is performed. The antilock brake operation by the mechanism is performed. Therefore, if the braking force due to the pressure contact of the auxiliary friction material is smaller than the braking force due to the pressure contact of the main friction material, the anti-lock brake operation is first performed by the auxiliary brake mechanism, and even if the lock is not released by that operation, The anti-lock braking operation is performed by the main braking mechanism.

According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the main brake mechanism transmits the operation of the brake operating member to the main friction material by hydraulic pressure. The sub-brake mechanism has a sub-transmission line that is provided independently of the main transmission line and that operates the sub-friction material by hydraulic pressure.

Therefore, when the brake operating member is operated, the operating force is transmitted by hydraulic pressure to the main friction material through the main transmission line. In response to this transmission, the main friction material comes into pressure contact with the brake disc, and the wheels are braked by the friction generated between them. Further, the anti-lock brake operation by the main brake mechanism is performed by changing (increasing or decreasing) the hydraulic pressure applied to the main friction material. Liquid pressure fluctuation (increase / decrease)
The reaction force when doing is transmitted to the brake operating member as kickback.

On the other hand, during the operation of the brake operating member, a hydraulic pressure is applied to the auxiliary friction material through the auxiliary transmission line, and the auxiliary friction material is brought into pressure contact with the brake disc by this hydraulic pressure, and the friction generated between them causes The wheels are braked. Further, the fluid pressure applied to the auxiliary friction material is changed (increased or decreased), whereby the intermittent brake operation by the auxiliary brake mechanism is performed. Here, the operating force of the brake operating member does not directly act on the sub transmission line independent of the main transmission line. Therefore, even if the hydraulic pressure fluctuates (increases or decreases), the reaction force is not transmitted to the brake operating member. Further, in the invention according to claim 4, even when the anti-lock braking operation is performed by the sub-brake mechanism, the reaction force due to the change in hydraulic pressure is applied to the brake operating member in the same manner as in the intermittent braking operation described above. Does not reach.

According to a sixth aspect of the present invention, in the fifth aspect of the invention, the first sub-brake control means further comprises hydraulic pressure detection means for detecting the hydraulic pressure in the main transmission line. It includes a pressure contact force changing means for changing the pressure contact force of the auxiliary friction material with respect to the brake disc according to the liquid pressure by the liquid pressure detecting means.

Therefore, when the sub brake mechanism is controlled by the first sub brake control means, the hydraulic pressure in the main transmission line is detected by the hydraulic pressure detecting means. This hydraulic pressure is
This differs depending on the operation of the brake operating member by the driver.
Then, the hydraulic pressure in the auxiliary transmission line acting on the auxiliary friction material is adjusted in accordance with the detected hydraulic pressure, and the pressure contact force of the auxiliary friction material with respect to the brake disc is determined by the hydraulic pressure detected by the hydraulic pressure detection means, and thus the brake operation. It is in accordance with the operation of the member. For this reason, the operating condition of the brake operating member by the driver, such as the operating amount and the operating speed, differs depending on the traveling condition.However, when the intermittent braking operation by the auxiliary brake mechanism is performed, the operating condition is appropriate. The auxiliary friction material is pressed against the brake disc by the generated force.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a "wheel brake control device" mounted on an automobile will be described below with reference to the drawings.

In the driver's seat of an automobile, as shown in FIG.
A brake pedal 1 as a brake operating member is provided. On the other hand, a plurality of (for example, four) wheels 3 are provided on the vehicle body.
Is rotatably mounted. Although only one wheel 3 is shown in FIG. 1 for convenience of explanation, the same applies to the remaining wheels. Further, a disc-shaped brake disc (also referred to as a disc rotor) 4 is provided for each wheel 3 so as to be integrally rotatable.

A main caliper 5 is attached to the vehicle body so as to straddle the outer peripheral portion of each brake disc 4.
Each main caliper 5 has the same structure as a caliper mounted on a general automobile. That is, the main caliper 5 is a cylinder, a piston accommodated in the cylinder so as to reciprocate, a main friction member arranged on the outer peripheral portion of the brake disc 4, and contacting and separating from the brake disc 4 by the reciprocating movement of the piston. And a main pad 6 as In each main caliper 5, when hydraulic pressure acts on the cylinder, the piston is pushed out, and the main pad 6 is brought into pressure contact with the brake disc 4. Due to the friction between the main pad 6 and the brake disc 4 due to this pressure contact, the wheel 3
Rotation is braked.

On the vehicle body, an auxiliary caliper 7 having a structure similar to that of the main caliper 5 and having an auxiliary pad 8 as an auxiliary friction material is arranged so as to straddle the outer peripheral portion of the brake disc 4 for each wheel 3. Installed. Then, as shown in FIG. 2 or 3, the sub pad 8 is installed at a location adjacent to the location where the main pad 6 is arranged in each brake disc 4. Therefore, the sub pad 8 is arranged in a form independent of the main pad 6, and can operate without being influenced by the operation of the main pad 6. The area of each sub-pad 8 involved in braking (braking effective area) is
It is smaller than the effective braking area of the main pad 6, for example, about half. In addition, the brake disc 4 has a sub pad 8
There are two places for arranging. The auxiliary pad 8 is shown in FIG.
Alternatively, as shown in FIG. 3, it may be arranged on at least one of the front and rear sides of the main pad 6.

As shown in FIG. 1, in order to transmit the depression operation of the brake pedal 1 to the main pad 6 of each wheel 3,
The pressure (fluid pressure) of the brake fluid 30 is used. Specifically, the brake pedal 1 is connected to a common (one) main master cylinder 16 for converting the operating force applied to the pedal 1 into hydraulic pressure. Main master cylinder 1
The same number of main transmission pipes 17 as the number of wheels 3 are connected to 6 and each main caliper 5 is connected to each pipe 17.

The main master cylinder 16 has a structure similar to that of a master cylinder used in a general automobile brake device, and performs the following operation. When the brake pedal 1 is depressed, the main push rod 18 overcomes the return spring and advances the piston. With this advance,
When the primary cup incorporated in the piston closes the oil escape hole communicating with the reservoir tank, the hydraulic pressure of the brake fluid 30 in the cylinder rises. This hydraulic pressure is the brake fluid 3
When a small spring at the 0 outlet is overcome, the check valve is opened and brake fluid 30 is supplied to each main transmission line 17. On the other hand, when the depression force on the brake pedal 1 is weakened, the piston is returned to its original position by the return spring, and the check valve is returned by the spring to close the outlet of the brake fluid 30.

A main hydraulic unit 19 for varying the hydraulic pressure transmitted to the main caliper 5 is provided in the middle of each main transmission line 17. The main solenoid valve 21 forming a part of the main hydraulic unit 19 is composed of a fixed iron core 22, a movable iron core (main plunger) 23, a solenoid 24, a spring 25, and the like, and a housing 26 that accommodates them. Each housing 26 has a first port 27, a second port
The port 28 and the third port 29 are open. The first port 27 is connected to the main master cylinder 16 through the main transmission line 17, and is always open regardless of the position of the main plunger 23. The second port 28 is the main transmission line 17
To the main caliper 5 and the third port 29 is connected to the main reservoir 32. The main plunger 23 has a liquid passage 33 and is reciprocally housed in a housing 26. The spring 25 connects the main plunger 23 to the first
It always urges away from the port 27.

The main solenoid valve 21 is the solenoid 2
By utilizing the fact that the magnetic attraction force is generated between the fixed iron core 22 and the main plunger 23 by energizing 4, the current to the solenoid 24 is changed to adjust the magnetic attraction force and resist the spring 25. It is a valve in which the main plunger 23 is located at any one of the "reference position", the "hydraulic pressure reducing position" and the "hydraulic pressure holding position", and the second port 28 and the third port 29 are opened and closed. . In the reference position, as shown in FIG. 1, the main plunger 23 is farthest from the first port 27, the outlet of the liquid passage 33 coincides with the second port 28, and the third port 29 is closed. At the hydraulic pressure reducing position, as shown in FIG. 5A, the main plunger 23 is located above the reference position, and the second port 28 and the third port 29 are opened. At the hydraulic pressure holding position, as shown in FIG. 5B, the main plunger 23 is located at an intermediate portion between the reference position and the hydraulic pressure reducing position, and the second port 28 is opened.
The third port 29 is closed.

As shown in FIG. 1, in each main transmission line 17, the upstream portion of the main solenoid valve 21 and the main reservoir 32 are connected by a hydraulic pressure supply line 34. In the middle of the hydraulic pressure supply line 34, the main pump 36 which is operated by the main motor 35 and supplies the brake fluid 30 in the main reservoir 32 to the main solenoid valve 21 and the flow of the brake fluid 30 are limited in one direction. The check valve 37 is provided. Then, the main master cylinder 1 described above
6, the main transmission line 17, and the main hydraulic unit 19 constitute a main brake mechanism 20.

In order to operate each sub pad 8, the wheels 3
A sub-master cylinder 41, a sub-hydraulic pressure unit 42, and a sub-transmission conduit 43 are provided for each. Each sub master cylinder 41 has the same configuration as the main master cylinder 16 described above, but is different in the following points. In the main master cylinder 16, the main push rod 18 is directly connected to the brake pedal 1, and the main push rod 18 is directly driven by the depression operation of the brake pedal 1, whereas in the sub master cylinder 41, the sub push rod 18 is driven. Reference numeral 44 is drivingly connected to a power source via a transmission mechanism 45. Here, the motor 46 is used as a power source. As the transmission mechanism 45, any type may be adopted. For example, a rack is formed on the auxiliary push rod 44, a pinion is attached to the rotation shaft of the motor 46, and the pinion is engaged with the rack to form the motor 46. It is also possible to change the rotational movement of the above into a linear movement and transmit it to the rack to reciprocate the auxiliary push rod 44.

Each sub transmission line 43 connects each sub master cylinder 41 to each sub caliper 7 in a state completely independent of the main transmission line 17. Each sub hydraulic unit 42
Is for changing the hydraulic pressure of the brake fluid 50 transmitted to the sub caliper 7, and is provided in the middle of the sub transmission line 43. The sub-solenoid valve 47 forming a part of each sub-hydraulic unit 42 includes a fixed iron core 48, a movable iron core (sub-plunger) 49, a solenoid 51, a spring 52, and the like, and a housing for housing them, like the main hydraulic unit 19. And 53. The first port 54, the second port 55, and the third port 56 are opened in each housing 53, the liquid passage 57 is formed in the sub plunger 49, and the sub reservoir 58 is connected to the third port 56. In the middle of the liquid supply line 59, the auxiliary motor 6
Sub pump 62 and check valve 63 operated by 1
The point that is provided is similar to that of the main hydraulic unit 19. The sub-master cylinder 41, the sub-transmission conduit 43, and the sub-hydraulic pressure unit 42 constitute the sub-brake mechanism 40.

Further, in order to detect the running state of the automobile, a wheel speed sensor 64 for each wheel 3, a common pressure sensor 65, a common stop lamp switch 66 and a common vehicle speed sensor 67 are attached to the vehicle body. There is. Each wheel speed sensor 64 is for detecting the rotation speed of the wheel 3. The stop lamp switch 66 corresponds to a brake operation detecting means, and detects whether or not the brake pedal 1 is depressed. Stop lamp switch 66
Is originally incorporated in an automobile in order to turn on a stop lamp in conjunction with the brake pedal 1. Here, the detection signal of the switch 66 is used. The vehicle speed sensor 67 is incorporated in, for example, a transmission, and detects the traveling speed of the vehicle body by driving a reed switch or a magnetic sensitive element with a magnet rotated by the rotation of the gear of the transmission.

The pressure sensor 65 is the main master cylinder 16
It is for detecting the hydraulic pressure P of the brake fluid 30 due to. Here, the pressure sensor 65 may be of any type, but it is desirable that it can detect a continuous change in the hydraulic pressure P. For example, a valve having the same structure as the main solenoid valve 21 described above and using the same operation principle can be cited. The difference is that the liquid passage 33 of the main plunger 23 is omitted, the second port 28 and the third port 29 of the housing 26 are omitted, and a constant current is supplied to the solenoid 24. , The hydraulic pressure is applied to the main plunger 23 to reciprocate, the voltage change in the solenoid 24 due to the reciprocating motion is detected, and the hydraulic pressure is calculated based on the detected value. Instead of the above type, a generally known Bourdon tube type, bellows type, or diaphragm type pressure sensor may be used.

Each sensor 64, 65, 67 and switch 6
The control device 6 for driving and controlling the motors 35, 46, 61 and the solenoid valves 21, 47 on the basis of the detected values of 6
8 are provided. The control device 68 includes a read only memory (ROM), a central processing unit (CPU), a random access memory (RAM), and the like. The ROM stores a predetermined control program and initial data in advance, and
U executes various arithmetic processes according to the control program of the ROM and the like. The RAM temporarily stores the calculation result by the CPU.

Next, the operation and effect of this embodiment configured as described above will be described. The flowcharts of FIGS. 6 and 7 show a brake control routine for controlling both the main and auxiliary brake mechanisms 20 and 40 among the respective processes executed by the control device 68. Further, the flowcharts of FIGS. 8 and 9 show a subroutine executed in the brake control routine.

In the brake control routine, the controller 68
First, in step S5, it is determined whether the ABS operation or the intermittent braking operation (these will be described later) is necessary. Specifically, it is determined whether the vehicle speed detected by the vehicle speed sensor 67 is higher than a predetermined value α. The predetermined value α is set to a relatively small value, for example, 10 km / h. If this determination condition is not satisfied, that is, if the vehicle is traveling at a low speed or has stopped traveling, the brake control routine ends. On the other hand, if the determination condition of step S5 is satisfied, that is, if the vehicle is traveling at a speed higher than a certain level, the process proceeds to step S10. Here, as a situation in which the ABS operation or the intermittent braking operation is unnecessary, for example, in a vehicle equipped with an automatic transmission having a torque converter, a creep phenomenon (when the shift lever is at the traveling position, the accelerator pedal is not required to be depressed) There is a case where the brake pedal 1 is depressed in order to prevent the phenomenon that the automobile slowly moves. Also,
Even during braking while driving at a low speed of about 10 km / h,
It is considered that the ABS operation and the intermittent braking operation are unnecessary because the time to the stop is very short.

In step S10, it is determined based on the detection result of the stop lamp switch 66 whether the brake pedal 1 is depressed. If this determination condition is not satisfied, the brake control routine is ended, and if it is satisfied, in step S20, based on the hydraulic pressure P detected by the pressure sensor 65, the change amount of the hydraulic pressure P per unit time ( ΔP / Δt) is obtained, and it is determined whether or not the amount of change is less than or equal to a predetermined value β, that is, whether or not there is a rapid change in hydraulic pressure P due to sudden braking.

If this determination condition is not satisfied (the sudden braking is applied), the energization of the motor 46 is stopped and the sub push rod 44 of the sub master cylinder 41 is stopped in step S100. Control goes to step S110. On the other hand, if the determination condition of step S20 is satisfied (the sudden braking is not applied), the energization of both the main and sub solenoid valves 21 and 47 is stopped and the main and sub motor 35 is stopped in step S30. , 61 is stopped. Then, both the primary and secondary plungers 23 and 49 stop at the reference position (see FIG. 1). The third port 29, 56 is the plunger 2
Closed by 3,49, the second ports 28,55 coincide with the outlets of the liquid passages 33,57. Second port 28,
55 and the third ports 29, 56 are shut off, and the brake fluid 30, between the calipers 5, 7 and the reservoirs 32, 58,
Distribution of 50 becomes impossible. The first port 27, 54 and the second port 28, 55 are in communication with each other.

Therefore, in the main hydraulic pressure unit 19, the hydraulic pressure P corresponding to the state of depression of the brake pedal 1 is transmitted to the main caliper 5 through the main transmission pipe line 17. Main pad 6
However, the brake disc 4 is pressed against the brake disc 4 with a pressing force corresponding to the depression state of the brake pedal 1. Due to the friction between the brake disc 4 and the main pad 6 associated with this pressure contact, the wheels 3
Rotation is braked. At this time, the main pump 36
Therefore, the brake fluid 30 in the main reservoir 32 is not supplied to the main transmission line 17 through the hydraulic pressure supply line 34. Further, since the check valve 37 is provided, the brake fluid 3 in the main transmission line 17 is
The 0 will never return to the main reservoir 32.

Then, in step S40, the motor 46 is energized for a certain period of time, and then the energization is stopped for a certain period of time. This cycle of energization and de-energization is repeated.
At this time, a current corresponding to the hydraulic pressure P by the pressure sensor 65 is supplied. The rotation of the rotation shaft of the motor 46 due to this energization is transmitted to the sub push rod 44 through the transmission mechanism 45. By this transmission, the auxiliary push rod 44 overcomes the return spring and advances the piston in the same manner as when the brake pedal 1 is depressed. When the power is turned off,
The piston to which the biasing force of the return spring is applied tries to return to its original position, and the auxiliary push rod 44 automatically retracts. This backward movement is transmitted to the motor 46 via the transmission mechanism 45, and the rotation shaft thereof rotates in the reverse direction. The fluid pressure repeatedly fluctuates (increases or decreases) due to the reciprocating movement of the piston that is caused by the repeated energization and de-energization.

This change in hydraulic pressure is transmitted to the sub caliper 7 through the sub transmission line 43, and the sub pad 8 once lowers the pressure contact force to the brake disc 4 and then raises it. Then, the fluctuation cycle consisting of the decrease and increase of the pressure contact force is repeated. By this fluctuation cycle, anti-lock brake operation (hereinafter simply referred to as "ABS operation")
A braking operation similar to the above (hereinafter referred to as "intermittent braking operation") is performed. This intermittent braking operation can be said to be a kind of pumping braking operation like the ABS operation. During the fluctuation cycle, in addition to the braking by the pressure contact of the main pad 6 described above, the auxiliary pad 8 is pressed by the brake pad by the pressure contact force having a magnitude corresponding to the hydraulic pressure P, that is, the pressure contact force corresponding to the stepped state of the brake pedal 1. 4 is intermittently pressed.

Next, in step S50, it is determined based on the detection values of the wheel speed sensors 64 whether there is any wheel 3 that is in a state immediately before locking or in an initial state.
As a method of determination, a method of using only wheel deceleration as a control parameter, a method of using only slip ratio as a control parameter, a method of using wheel deceleration and wheel acceleration as control parameters, a wheel deceleration, a wheel acceleration and a slip ratio. Although there is a method of using a control parameter, any method may be used. For example, in the method of using only wheel deceleration as a control parameter, the wheel speed is differentiated to obtain the wheel deceleration, and when the wheel deceleration is smaller than a predetermined value, that is, when the wheel speed rapidly decreases, It is assumed that the state is immediately before the lock occurs or the initial state. Further, in the method using only the slip ratio as a control parameter, the slip ratio is obtained by dividing the difference between the vehicle body speed (or its approximate value) and the wheel speed by the vehicle body speed (or its approximate value),
When this slip ratio is larger than a predetermined value, it is assumed that the state is immediately before the lock occurs or the initial state.

If the determination condition in step S50 is not satisfied, the process returns to step S10, and if it is satisfied, the power supply to the motor 46 is stopped in step S60. In the sub master cylinder 41, the reciprocal movement of the sub push rod 44 is stopped due to the stop of the energization. The intermittent braking operation due to the cycle of fluctuations in the pressure contact force of the sub pad 8 ends. In step S60, the auxiliary motor 61 is energized to operate the auxiliary pump 62.

Subsequently, in step S70, the energization control process for the auxiliary solenoid valve 47 is executed. Specifically, in step S71 of FIG. 8, the auxiliary solenoid valve 47 is energized with the fourth set current I4, and the auxiliary plunger 49
Is moved to the hydraulic pressure reduction position. In this position, FIG.
As shown in (a), the pipeline between the sub master cylinder 41 and the sub caliper 7 is blocked, and the pipeline between the sub caliper 7 and the sub reservoir 58 is communicated. As shown by the arrow in FIG. 4A, the brake fluid 50 in the sub caliper 7 flows out to the sub reservoir 58, and the hydraulic pressure decreases. At this time, the sub-reservoir 58 is processed by the processing in step S60.
The brake fluid 50 therein is made high in pressure by the sub pump 62 and returned to the sub master cylinder 41 side (upstream of the sub solenoid valve 47).

In step S72, the current supplied to the sub-solenoid valve 47 is switched to the third set current I3 which is smaller than the fourth set current I4, and the sub-plunger 49 is hydraulically held as shown in FIG. 4 (b). Move to position. At this position, the outlet of the liquid passage 57 is separated from the second port 55 to open the second port 55, but the third port 5
6 is closed. The pipeline between the sub master cylinder 41 and the sub caliper 7 and the pipeline between the sub caliper 7 and the sub reservoir 58 are blocked, and as a result, the hydraulic pressure is maintained.

In step S73, the power supply to the auxiliary solenoid valve 47 is stopped. Then, as shown in FIG. 1, the sub-plunger 49 returns to the reference position, and the pipe line between the sub-master cylinder 41 and the sub-caliper 7 is in the communication state again. High-pressure brake fluid 50 from the sub master cylinder 41
Then, the brake fluid 50 discharged from the sub pump 62 flows into the sub caliper 7 again, and the hydraulic pressure increases. In this way, when the state immediately before locking or the initial state occurs, the pressure contact force of the sub pad 8 once decreases and then rises, so that the so-called ABS operation is performed. After performing the process of step S73, the process proceeds to step S80.

In step S80, the above-mentioned step S
Similar to 50, it is determined whether the state immediately before the lock or the initial state continues. If this determination condition is not satisfied, the brake control routine is terminated, and if it is satisfied, it is determined in step S90 whether or not a predetermined energization control termination condition is satisfied. The energization control ending condition may be, for example, that the energization control process of step S70 is repeated a predetermined number of times, a predetermined time has elapsed after the first energization control process was started, or the like. If the determination condition of step S90 is not satisfied, the process returns to step S70, and if the determination condition is satisfied, step S90 is performed.
Move to 110.

In step S110 after step S90 or S100, the sub motor 61 is stopped and the main motor 35 is operated. With the stop of the sub motor 61, the high pressure brake fluid 50 is not returned from the sub pump 62 to the sub master cylinder 41 side (the sub solenoid valve 47). At this time, the sub push rod 44 is returned by stopping the energization of the motor 46. Therefore, the sub pad 8 does not come into pressure contact with the brake disc 4, and the braking force of the sub pad 8 on the brake disc 4 decreases or disappears.

Next, in step S120, an energization control process for the main solenoid valve 21 is executed. The content of this process is the same as the process of step S70 described above. That is, in step S121 of FIG. 9, the second set current I2 is supplied to the main solenoid valve 21,
As shown in (a), the main plunger 23 is moved to the hydraulic pressure reducing position. At this position, the conduit between the main master cylinder 16 and the main caliper 5 is blocked, and the conduit between the main caliper 5 and the main reservoir 32 is connected. The brake fluid 30 in the main caliper 5 flows out to the main reservoir 32, and the hydraulic pressure decreases. At this time, the brake fluid 30 in the main reservoir 32 is transferred to the main pump 3 by the process of step S110.
The pressure is increased by 6 and is returned to the main master cylinder 16 side (upstream of the main solenoid valve 21).

In step S122, the current supplied to the main solenoid valve 21 is switched to the first set current I1 which is smaller than the second set current I2, and the main plunger 23 is hydraulically operated as shown in FIG. 5 (b). Move to holding position. In this position, the outlet of the liquid passage 33 is located at the second port 2
8, the second port 28 is opened and the third port 29 is closed. The conduit between the main master cylinder 16 and the main caliper 5 is also the main caliper 5 and the main reservoir 32.
The conduit between them is also blocked, so that hydraulic pressure is maintained.

In step S123, the power supply to the main solenoid valve 21 is stopped. Then, as shown in FIG. 1, the main plunger 23 returns to the reference position, and the conduit between the main master cylinder 16 and the main caliper 5 is in the communication state again. High-pressure brake fluid 30 in the main master cylinder 16,
The brake fluid 30 discharged from the main pump 36 flows into the main caliper 5 again, and the hydraulic pressure increases. Step S12
After performing the process of 3, the process proceeds to step S130.

In step S130, the above-mentioned step S5 is performed.
0, as in S80, it is determined whether the state immediately before locking or the initial state has ended. If this determination condition is not satisfied, the process returns to step S120, and if it is satisfied, the main motor 35 is stopped in step S140, the main pump 36 is stopped, and the brake control routine is ended.

The wheel speed sensor 64 and the process of step S50 in the brake control routine by the control device 68 correspond to the lock detecting means. The processing of step S120 in the same routine corresponds to the main brake control means, the processing of step S40 corresponds to the first sub brake control means, and the processing of step S70 corresponds to the second sub brake control means. The sub master cylinder 41, the transmission mechanism 45, the motor 46, and the process of step S40 in the brake control routine by the control device 68 correspond to the pressure contact force changing means.

As described above, in the present embodiment, during the period in which the main pad 6 is in pressure contact with the brake disc 4 by the depression operation of the brake pedal 1, before the wheels 3 reach the state immediately before locking or the initial state, the auxiliary The pad 8 repeats the cycle of pressure contact fluctuation. The braking force associated with the normal braking operation and the braking force associated with the intermittent braking operation of the auxiliary brake mechanism 40 are simultaneously applied to the wheels 3. At a certain timing, both the main pad 6 and the sub pad 8 are pressed against the brake disc 4, but immediately after that, only the sub pad 8 is separated from the brake disc 4 and the press contact force is weakened. Then, the sub pad 8 again comes into pressure contact with the brake disc 4. The fluctuation cycle of decreasing and increasing the pressure contact force is repeated. The intermittent braking operation of the sub pad 8 is similar to the ABS operation that is generally performed. Such simultaneous execution of the normal braking operation and the intermittent braking operation is performed by adding the sub pad 8 and by making the sub pad 8 independent from the main pad 6 so as not to be influenced by the operation of the main pad 6. It is possible to do. Since there are two pads, one pad (main pad 6) can perform a normal braking operation, and the other pad (sub pad 8) can perform an intermittent braking operation.

Therefore, unlike the prior art in which the ABS operation is not started unless the state immediately before the locking or the initial state is reached, the intermittent braking operation similar to the ABS operation can be performed even in the state immediately before that. In other words, while the brake pedal 1 is being depressed, the ABS operation or an operation similar to the ABS operation is always performed regardless of the state immediately before the lock or the initial state, and as a result, in the case of only the normal brake operation. Compared to this, locking is less likely to occur. In addition, in the related art, from normal braking operation to ABS
Unlike the case of accelerating the timing of switching to operation,
Since a large braking force is applied, the braking time and braking distance do not increase. The effect of shortening the braking distance, which is a characteristic of disc brakes, is not lost.

The present embodiment has the following features in addition to the matters described above. (A) The detection of the operation of depressing the brake pedal 1 by the stop lamp switch 66 is used as the start condition of the pressure contact fluctuation cycle. Therefore, when the brake pedal 1 is stepped on, the sub-brake mechanism 40 is pressed almost at the same time as the stepping.
The intermittent braking operation by is started. In this way, the intermittent braking operation is performed from an early stage, so that it is possible to make locking of the wheels 3 more difficult.

(B) The detection of the state immediately before the lock or the initial state is set as the condition for ending the cycle of the pressure contact force. Therefore, when the state immediately before the lock or the initial state is detected, the intermittent braking operation of the sub brake mechanism 40 is ended. The timing of this end is substantially the same as the timing of switching to the ABS operation by the sub-brake mechanism 40 after the normal braking operation accompanying the depression operation of the brake pedal 1 is completed. In this way, the intermittent braking operation is performed until the end of the normal braking operation (just before the ABS operation is started). Also in this respect, locking can be made even more difficult to occur.

(C) If the state immediately before the lock or the initial state is detected despite the intermittent braking operation by the auxiliary brake mechanism 40, the ABS by the main brake mechanism 20 is detected.
The operation is not performed suddenly, but first, the ABS operation by the auxiliary brake mechanism 40 is performed. Then, if the ABS operation by the sub-brake mechanism 40 does not cancel the state immediately before the locking or the initial state, the ABS operation by the main braking mechanism 20 is performed. Like this, ABS
Since the operation is performed stepwise, the lock of the wheel 3 can be efficiently released.

(D) When the main pad 6 performs the ABS operation, the reaction force of the fluctuation (increase / decrease) of the hydraulic pressure is transmitted to the brake pedal 1 as kickback. This phenomenon is the same as that which has occurred conventionally. However, such a problem does not occur when the sub pad 8 performs the intermittent braking operation and the ABS operation. This is because the sub transmission line 43 is provided independently of the main transmission line 17, and the brake pedal 1 is not directly connected to the sub transmission line 43. The hydraulic pressure in the main master cylinder 16 which changes according to the depression operation of the brake pedal 1 is detected, and the hydraulic pressure in the sub-transmission conduit 43 is varied based on the detection result. Therefore, the reaction force due to the fluctuation of the hydraulic pressure in the sub transmission line 43 is not transmitted to the brake pedal 1, and the driver does not feel uncomfortable due to kickback.

(E) During the intermittent braking operation, the sub pad 8 is brought into pressure contact with the brake disc 4 by the pressure contact force corresponding to the hydraulic pressure of the brake fluid 30 in the main transmission line 17. This hydraulic pressure varies depending on the driver's operation on the brake pedal 1. Therefore, the pressure contact force of the auxiliary pad 8 with respect to the brake disc 4 depends on the depression operation of the brake pedal 1. The manner of operation of the brake pedal 1 by the driver, for example, the operation amount, the operation speed, etc., differ depending on the traveling situation, but when the intermittent braking operation by the auxiliary brake mechanism 40 is performed, this operation method is suitable. The auxiliary pad 8 is pressed against the brake disc 4 by force. Since the intermittent braking operation is performed with a pressure contact force of a magnitude intended by the driver, it is possible to prevent the driver from feeling uncomfortable.

(F) When the sudden braking is applied and the lock is more likely to occur than during the normal braking, the intermittent braking operation and the ABS operation by the auxiliary braking mechanism 40 are omitted, and the ABS operation by the main braking mechanism 20 is immediately performed. I'm trying to do. For this reason, it is possible to prevent the lock from occurring easily even when the brake is suddenly applied, and to end the lock early when it occurs. It can handle excessive input in an emergency.

(G) Since the motor 46 is used as the power source of the sub master cylinder 41, the responsiveness to energization and de-energization is good, and the stroke of the reciprocating movement of the sub push rod 44 can be easily finely adjusted.

(H) Since the sub-pad 8 bears a part of the braking force conventionally taken by the main pad 6, the main pad 6
The load on the can be reduced. Along with this, the degree of freedom in design such as the arrangement of the main pads 6 increases.

(I) Generally, an operating noise is generated during the ABS operation. It is considered that this operating sound is caused by vibration and sound accompanying dynamic change of hydraulic pressure, propagation of vibration of the hydraulic unit to the vehicle body, sound generated from the hydraulic unit, and the like. In the present embodiment, the wheels are less likely to be locked as described above, so the number of ABS operations is reduced as compared with the conventional antilock brake device that does not have the auxiliary brake mechanism 40. Along with this decrease, the operating noise during the ABS operation is reduced.

The present invention can be embodied in another embodiment shown below. (1) A device (traction control device) that prevents the drive wheels from idling when starting or accelerating on a slippery road surface, or when traveling on a curved road,
The present invention may be used in combination with a device (vehicle stability control device) that prevents the vehicle from skidding due to strong over-steering or under-steering. This has the effect of reducing the load on the main braking mechanism 20.

(2) At least one of the start condition and the end condition of the pressure contact force variation cycle by the sub pad 8 may be changed to a condition different from that of the above embodiment. For example, when the brake pedal 1 is depressed, the stop lamp switch 66
It is also possible to set the start condition to be the lapse of a predetermined time after being detected by, or the end condition to be the lapse of a certain time from then.

(3) The ABS operation by the sub brake mechanism 40 may be omitted, and the ABS operation by the main brake mechanism 20 may be performed when the state immediately before the lock or the initial state is detected.

(4) In the above embodiment, the stroke of the sub push rod 44 is changed according to the hydraulic pressure in the main master cylinder 16, but the sub push rod 44 is always reciprocated with the same stroke regardless of this hydraulic pressure. You may move it.

[0070]

As described above, according to the first aspect of the present invention, it is possible to prevent the wheels from locking without increasing the braking time or the braking distance.

According to the invention of claim 2, claim 1
In addition to the effect of the invention described in (1), the intermittent braking operation by the sub-brake mechanism is performed from an early stage, so that it is possible to further prevent locking of the wheels.

According to the invention of claim 3, claim 1
Alternatively, in addition to the effect of the invention described in 2, the intermittent braking operation by the sub-brake mechanism is performed until the wheel is in a state immediately before locking or in an initial state, so that locking can be made even more difficult.

According to the invention of claim 4, claim 1
In addition to the effect of the invention described in any one of 1 to 3, the wheels can be efficiently unlocked by performing the antilock brake operation stepwise.

According to the invention of claim 5, claim 1
In addition to the effect of the invention described in any one of to 4, it is possible to prevent kickback from occurring when the sub-brake mechanism performs an intermittent braking operation or an antilock braking operation.

According to the invention of claim 6, claim 5
In addition to the effect of the invention described in (1), the sub-brake mechanism can perform an intermittent braking operation with a pressure contact force of a magnitude intended by the driver, so that the driver does not feel uncomfortable.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a wheel brake control device.

FIG. 2 is an explanatory diagram showing a positional relationship between a main pad and a sub pad with respect to a brake disc.

FIG. 3 is an explanatory diagram showing a positional relationship between a main pad and a sub pad with respect to a brake disc.

4 (a) and 4 (b) are schematic configuration diagrams for explaining the operation of the auxiliary brake mechanism.

5 (a) and 5 (b) are schematic configuration diagrams for explaining the operation of the main brake mechanism.

FIG. 6 is a flowchart illustrating a brake control routine.

FIG. 7 is a flowchart illustrating a brake control routine.

FIG. 8 is a flowchart illustrating a sub-solenoid valve energization control processing routine.

FIG. 9 is a flowchart illustrating a main solenoid valve energization control processing routine.

[Explanation of symbols]

1 Brake Pedal as a Brake Operation Member 3 Wheel 4 Brake Disc 6 Main Pad as a Main Friction Material 8 Sub Pad as a Sub Friction Material 10 Rotation Center 11 Opposing Region 12 Intermediate Region 17 Main Transmission Pipeline 20 Main Brake Mechanism 40 Sub Brake Mechanism 41 Sub-master cylinder 43 forming a part of the pressure contact force changing means Sub transmission line 45 Transmission mechanism 46 forming a part of the pressure contact force changing means Motor 64 forming a part of the pressure contact force changing means Wheel speed sensor 65 constituting a part of the pressure sensor 66 as a hydraulic pressure detection means 66 stop lamp switch 68 as a brake operation detection means part of the lock detection means, main brake control means, first sub-brake control means, pressure contact force change Part of the means and second
A control device that functions as an auxiliary brake control means.

Claims (6)

[Claims] 1. A brake disc that rotates integrally with a wheel, a main brake mechanism that presses a main friction material against the brake disc according to the operation of a brake operating member to brake the wheel, and a state immediately before locking of the wheel. Alternatively, a wheel brake control device including lock detection means for detecting an initial state and main brake control means for temporarily reducing the pressure contact force of the main friction material in the main brake mechanism according to the detection result of the lock detection means. A sub-brake mechanism that presses a wheel by pressing a sub-friction material provided separately from the main friction material to the brake disc, wherein the sub-friction material is arranged on the brake disc. And a structure in which the main friction material and the sub friction material are connected to each other by arranging them in a form adjacent to and independent of each other. During operation, prior to the detection by the lock detecting means, there is provided a first sub-brake control means for causing the sub-brake mechanism to repeat a fluctuation cycle in which the pressure contact force of the sub-friction material is reduced and then increased. Brake control device for wheels. 2. A structure in which, in the brake disc, the sub-friction material is arranged adjacent to and independent of a region where the main friction material is arranged, and the main friction material and the sub-friction material are connected to each other. The wheel brake control device further includes brake operation detecting means for detecting an operation of the brake operating member, wherein the first sub-brake control means detects the brake operation by the brake operation detecting means by the pressing force. The brake control device for a wheel according to claim 1, wherein the condition is set as a start condition of the variable cycle of. 3. In the brake disc, the sub-friction material is arranged adjacent to and independent of the area where the main friction material is arranged, and the main friction material and the sub-friction material are connected to each other. In the wheel brake control device described above, the first sub-brake control means sets the detection of the immediately preceding state or the initial state of the lock by the lock detection means as the ending condition of the pressure contact variation cycle. The wheel brake control device according to claim 1, wherein the brake control device is a wheel brake control device. 4. In the brake disc, a structure in which the sub-friction material is arranged adjacent to and independent of a region in which the main friction material is arranged so that the main friction material and the sub-friction material are connected to each other. In the wheel brake control device described above, after the control of the sub-brake mechanism by the first sub-brake control means is completed and prior to the control of the main brake mechanism by the main brake control means, a state immediately before locking by the lock detection means or The second sub-brake control means for causing the sub-brake mechanism to repeatedly decrease and increase the pressure contact force of the sub-friction material under the condition that the initial state is detected is further provided. The brake control device for a wheel according to one. 5. In the brake disc, a structure in which the sub-friction material is arranged adjacent to and independent of a region in which the main friction material is arranged, and the main friction material and the sub-friction material are connected to each other. In the wheel brake control device described above, the main brake mechanism has a main transmission line that transmits the operation of the brake operating member to the main friction material by hydraulic pressure, and the sub-brake mechanism is the main transmission line. The wheel brake control device according to any one of claims 1 to 4, further comprising a sub-transmission pipe line that is provided independently of the road and that operates the sub-friction material by hydraulic pressure. 6. The structure in which the sub-friction material is arranged adjacent to and independent of the area in which the main friction material is arranged in the brake disc so that the main friction material and the sub-friction material are connected to each other. The wheel brake control device further includes a hydraulic pressure detection means for detecting a hydraulic pressure in the main transmission line, and the first sub-brake control means is configured to operate in accordance with the hydraulic pressure detected by the hydraulic pressure detection means. The wheel brake control device according to claim 5, further comprising a pressure contact force changing unit that changes a pressure contact force of the auxiliary friction material with respect to the brake disc.