JP2000211490A - Brake force control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate insufficiency of brake fluid within an accumulator arranged within a brake force control device in the brake force control device having a traction control function. SOLUTION: This brake device is provided with an automatic brake function capable of pumping up brake fluid pressure within an accumulator 15 by a fluid pressure pump 21, supplying fluid pressure from the accumulator 15 to a wheel cylinder 3' by the state of a vehicle and automatically working a brake. The accumulator 15 is provided with a fluid amount detection means and is connected to the wheel cylinder 3' via a normally closed type switching valve 17. When the fluid amount detection means detects that an accumulator fluid amount is a prescribed value or below, a part of brake fluid pressure supplied to the wheel cylinder 3' is supplied to the accumulator 15 by opening the changeover valve 17 when the brake is worked.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic brake function for automatically operating a brake under predetermined conditions to brake a vehicle, and to apply a brake to a drive wheel when the vehicle slips when the vehicle starts moving. The present invention relates to a brake force control device having a traction control function for solving a problem, and particularly to a brake force control device excellent in safety which can solve a shortage of a brake fluid amount in an accumulator arranged in the brake force control device.

[0002]

2. Description of the Related Art Conventionally, there has been known an automatic brake device disclosed in Japanese Patent Application Laid-Open No. Hei 6-107141. The automatic brake device described in the above publication includes a pressurizing unit and a pre-pressurizing unit (accumulator), and switches the electromagnetic valve in the hydraulic circuit at the time of a failure to thereby store the pressure fluid stored in the pre-accumulator. Is supplied to the wheel cylinder so that the brake can be operated. By the way, the brake fluid in the accumulator is mechanically sealed so that a predetermined amount of fluid is maintained at all times.However, it is not possible to completely prevent the leakage of the fluid from the seal portion. If the accumulator is stopped for a period of several months (for example, during a business trip, etc.), the accumulator is not replenished with brake fluid, and the amount of brake fluid in the accumulator is insufficient due to leakage of the accumulator. Occurs.

[0003]

In addition to this, there is also known another type in which the brake fluid is mechanically replenished during normal brake operation in response to the above-described insufficient accumulator weight reduction. However, in any of the above cases, the vehicle is stopped for a long period of time (for example, the vehicle is stopped for several months on a business trip or the like).
And the replenishment of the brake fluid to the accumulator is not performed,
Also, since the brake pedal is not depressed,
Insufficient brake fluid level to the accumulator occurs. After such a situation, especially in the case of accumulating pressure in the accumulator by depressing the brake pedal, it is necessary to start the car and depress the brake only several times,
Due to insufficient accumulation of pressure in the accumulator, sufficient automatic braking function and traction control function cannot be exhibited, and the driver cannot be informed of such a situation, which poses a problem in safety. In addition, automatic braking devices using pre-pressurizing means
Usually, since the accumulator used as the pre-pressurizing means is of a high pressure and high capacity type, there is a problem that the volume and weight of the pressurizing means (accumulator) are large, and the cost is high. There is a demand for improvement in terms of weight reduction and cost reduction.

[0004] Therefore, the present invention enables an alarm device to notify the driver of a shortage of the accumulator fluid level when the vehicle is started and, if the brake fluid level in the accumulator is insufficient, at the time of starting the vehicle. By using the hydraulic pressure generated in the master cylinder by the brake operation, the brake fluid can be immediately supplied to the accumulator, and even if the vehicle has been stopped for a long time, it is possible to accumulate sufficient pressure in the accumulator. The purpose is to solve the problem. Furthermore, instead of using the conventional high-pressure, high-capacity accumulator, a small low-pressure accumulator is used, and at the time of automatic braking, the hydraulic pump is operated, and the brake fluid is quickly combined with the hydraulic pressure from the small accumulator. It is an object of the present invention to provide a brake force control device that can supply the brake force to a wheel cylinder, secure responsiveness, and reduce the size of the device.

According to the present invention, a small and low-pressure accumulator is provided in a hydraulic circuit, and a brake fluid pressure generated in the circuit in a normal use state is constantly accumulated in the accumulator. The brake fluid from the pump is pumped up by a hydraulic pump so that the brake can be operated. In addition, even if the brake fluid level in the accumulator is insufficient for a long period of time when the vehicle has been stopped, the driver is notified of the lack of the accumulator fluid level by an alarm device when the vehicle starts, and the first brake By utilizing the hydraulic pressure generated in the master cylinder by the operation, it is possible to immediately supply the pressure into the accumulator, thereby enabling a sufficient pressure accumulation in the accumulator, and obtaining a stable automatic braking function or traction function. A cut valve that shuts off communication with the master cylinder and a self-keep valve in the circuit are provided.When a predetermined hydraulic pressure is generated in the circuit, the self-keep valve automatically shuts off the circuit and energizes the cut valve. Even if it is stopped, the fluid pressure state can be maintained, and the accumulator used in the present device can be of a small and low pressure that can accumulate the brake fluid pressure generated during normal operation. Further, at the time of traction control, the discharge pressure from the hydraulic pump for automatic braking can be adjusted by the relief valve, so that the operating load of the hydraulic pump during control can be reduced.

[0006]

The technical solution adopted by the present invention is to pump the brake fluid pressure in the accumulator by a fluid pressure pump and supply the fluid pressure from the accumulator to the wheel cylinder depending on the condition of the vehicle. In a brake force control device having an automatic braking function capable of automatically operating a brake, the accumulator includes a liquid amount detecting means and is connected to a wheel cylinder via a normally-closed switching valve. When the liquid amount detecting means detects that the accumulator liquid amount is equal to or less than a predetermined value, the switching valve is opened at the time of braking to supply a part of the brake liquid pressure supplied to the wheel cylinder to the accumulator. A braking force control device characterized by the following.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of the present braking force control device, and FIG. 2 is an enlarged sectional view of a self-keeping valve in the device. 3 is an enlarged sectional view of a guarantee valve in the apparatus, FIG. 4 is an enlarged sectional view of a low-pressure accumulator in the apparatus, FIG. 5 is an enlarged sectional view of a hydraulic pump in the apparatus, and FIG. It is a block diagram of a control apparatus. Hereinafter, after describing the overall configuration of the brake force control device, the components of the self-keeping valve, the guarantee valve, the low-pressure accumulator, the hydraulic pump, and the electronic control device that performs the hydraulic control will be described in detail.

As shown in FIG. 1, the brake circuit of the present embodiment comprises two systems for the front wheels and the rear wheels. Each system is provided with a master cylinder 2 for generating a hydraulic pressure by depressing a brake pedal 1, as shown in FIG. The brake pedal 1 is provided with a brake switch 40 for detecting depression of the brake pedal.

The front wheel brake system includes a first cut valve 4, a hold valve 5, a decay valve 6, a front wheel hydraulic pump 7, a front wheel anti-lock control reservoir 8, and a damper 9 between the master cylinder 2 and the wheel cylinder 3.
An anti-lock control modulator consisting of, for example, is disposed. The first cut valve 4 is configured as a normally-open two-position switching valve, and a check valve 4 a is provided in parallel with the first cut valve 4. Further, the damper 9 is provided to alleviate kickback of the brake pedal during the anti-lock control. The damper 9 includes a damper piston 9b and a damper spring 9c in a damper cylinder 9a. The damper piston 9b is normally operated by the damper spring 9c. The liquid chamber 9 d is urged downward in the drawing to form a damper piston 9.
The liquid discharged from the front wheel hydraulic pump 7 can flow into the liquid chamber 9d defined by b.

The rear wheel brake system includes a master cylinder 2
Is connected to a first port 12a of the self-keeping valve 12 (detailed configuration will be described later), a second port 12b of the self-keeping valve 12 is connected to a pipeline 13, and in the same pipeline 13, A second cut valve 11 and a guarantee valve 14 as a normally-open two-position switching valve are arranged. The line 13 from the second cut valve 11 is connected to the fourth port 12 d of the self-keep valve 12 and the line 3.
2 and communicates with a first port 14a of a guarantee valve 14 (detailed configuration will be described later), and a second port 14b of the guarantee valve 14 is connected to a rear wheel cylinder 3 'via a hold valve 5'. ing.

A third port 14c of the guarantee valve 14 communicates with a port 15a of the low-pressure accumulator 15 and a discharge port 1 of a hydraulic pump 16 for a rear wheel.
6c and the second switching valve 18. A port 15 is provided in a flow path connecting the second port 14b of the guarantee valve 14 and the port 15a of the low-pressure accumulator 15.
A check valve 22 that allows the flow from the port a to the second port 14b is arranged.

The rear wheel cylinder 3 'is connected to a first suction port 16a of a rear wheel hydraulic pump 16 and a rear wheel anti-lock control reservoir 23 via a decay valve 6'. Rear wheel hydraulic pump 1 via pressure sensor 20 and first switching valve 17
No. 6 communicates with the second suction port 16b. The automatic brake hydraulic pump 21 is of a type driven by a motor (not shown) by a cam 24 common to the front wheel hydraulic pump 7 and the rear wheel hydraulic pump 16 described above. The suction port 21a of the low-pressure accumulator 15 communicates with the port 15a of the low-pressure accumulator 15 via the second switching valve 18, and the discharge port 21b of the second cut valve 11
And a line 32 communicating the guarantee valve 14 and a third port 12 c of the self-keeping valve 12 via a third switching valve 19. A relief valve 19 a for preventing the discharge pressure of the automatic brake hydraulic pressure pump 19 from becoming excessive is disposed in a pipe provided in parallel with the third switching valve 19.

The above-mentioned first switching valve 17, second switching valve 18,
Each of the third switching valves 19 is configured as a normally closed two-position switching valve, and the second cut valve 11 is a check valve 11a.
, And is configured to open and close the flow path in response to a command from the electronic control unit. The liquid recirculation type anti-lock control modulator (5,
5 ', 6, 6', 7, 16, 8, 23) are conventionally known ones. In the front wheel system and the rear wheel system, various valves, switching valves, hydraulic pumps, and the like in the above-described configuration are commanded from an electronic control device that operates based on signals from various sensors that detect the state of the vehicle body. Executes anti-lock control or automatic brake control.

Next, components such as the self-keeping valve 12, the guarantee valve 14, the low-pressure accumulator 15, the hydraulic pumps 7, 16, 21 and the electronic control unit will be described in detail. [Self-keeping valve 12] As shown in FIG. 2, the self-keeping valve 12 has a first port 12a, a second port
It has a port 12b, a third port 12c, and a fourth port 12d, and a self-keeping piston 12f is slidably disposed in a cylinder 12e communicating these.
The self-keeping piston 12f is biased rightward in the figure by a return spring 12h, and the self-keeping piston 12f is provided with a valve element 12g, which resists the urging force of the return spring 12h. Then, by moving to the left and contacting the left wall surface of the cylinder 12e, the first port 12a (and the third port 1
The communication between 2c) and the second port 12b is interrupted. Further, the self-keeping piston 12f is in contact with the small-diameter piston 12i arranged in the fourth port 12d, and the hydraulic pressure acting on the fourth port 12d becomes a predetermined value (P1
= F / A, where F is the force of the return spring, and A is the pressure receiving area of the small diameter piston 12i), the small diameter piston 12i and the self-keeping piston 12f move to the left while bending the return spring 12h, and the first
The communication between the port 12a, the third port 12c and the second port 12b is cut off.

[Guarantee Valve 14] As shown in FIG. 3, the guarantee valve 14 has a first port 14a, a second port 14b, and a third port 14c in a valve body, and a guarantee piston 14e is provided in a cylinder 14d.
Are slidably arranged, and the guarantee piston 1
4e is urged leftward in the figure by a return spring 14f arranged in the cylinder 14d. The guarantee piston 14e is provided with a valve body 14g. When the valve body 14g contacts the left wall surface of the cylinder 14d, the communication between the second port 14b and the third port 14c is interrupted. I have. The third port 14c is moved from the third port 14c to the second port 14c by the urging force of the spring.
First check valve 14h that cuts off communication in the direction of port 14b
Is provided. The check valve 14h has a function of allowing a flow from the second port 14b to the third port 14c.

A passage 14i is formed in the guarantee piston 14e. The passage 14i communicates with the second port 14b through a gap 14k formed around the guarantee piston 14e, and also communicates with the first port 14a. A second check valve 14m composed of a spring and a ball is disposed in the passage 14i. The second check valve 14m has a function of allowing a flow from the first port 14a to the second port 14b. The first port 14a and the second port 14b communicate with each other through an orifice 14n as shown in the figure.

In the state shown, the guarantee valve 14 blocks the communication between the second port 14b and the third port 14c, and when the hydraulic pressure of the master cylinder 2 flows in from the first port 14a side. , 2nd check valve 1
Hydraulic pressure can be discharged to the wheel cylinder 3 'through the 4m, the orifice 14n and the second port 14b. Further, when the hydraulic pressure on the second port 14b side increases, a hydraulic pressure difference is generated between the left and right end surfaces of the guarantee piston 14e by the action of the orifice 14n, and the guarantee piston 14e moves rightward in the figure to open the valve body 14g. The hydraulic pressure can flow out from the second port 14b to the third port 14c via the first check valve 14h.

[Low-pressure accumulator 15] As shown in FIG. 4, the low-pressure accumulator 15 has a hydraulic chamber 15c defined by an accumulator piston 15b slidably disposed in the accumulator main body, and the hydraulic chamber 15c has a port 15a. Via the second switching valve 18 and the third port 14c of the guarantee valve 14 and the check valve 2
2 through the second port 14b. The accumulator piston 15b is constantly urged rightward in the figure by the urging force of a spring 15d, and the accumulator piston 15b has a detection rod 15 for detecting a position.
e is provided, and the end of the detection rod 15e is in contact with the limit switch 15f.

The low-pressure accumulator 15 maintains the initial state indicated by the dotted line in the figure when the hydraulic pressure is not acting on the hydraulic chamber 15c (for example, at the time of shipment), and the wheel cylinder 3 'when the brake is released. The hydraulic pressure in the hydraulic chamber 15
c, the accumulator piston 15b is moved to the left in the figure, and a predetermined hydraulic pressure (liquid amount) can be accumulated in the hydraulic pressure chamber 15c in the illustrated state. When the accumulator piston 15b comes to the left position (accumulated state) as shown, the state can be detected by the limit switch 15f.

[Hydraulic Pumps 7, 16, 21] As shown in FIG. 5, the hydraulic pumps 7, 16, 21 for the front wheels, the rear wheels, and the automatic brakes have a conventionally known plunger type hydraulic pressure pump. The pump is a pump, and the respective pistons 7a, 16e, 21e reciprocate by rotating the cam 24 to pump up liquid from the suction ports 7b, 16a, 16b, 21a and discharge liquid from the discharge ports 7c, 16c, 21b. Things. However, the rear wheel hydraulic pump 16 is a conventional ABS.
The configuration is different in that a second suction port 16b for automatic brake control, which is a feature of the present invention, is provided in addition to the first suction port 16a for control, but the function of the pump is not changed.

[Electronic control device]
The electronic control unit includes a wheel speed sensor (Vw), a brake switch (SW), a clutch switch (SW), a parking switch (SW), a gear switch (SW), a limit switch (15f), a pressure switch, as shown in FIG. A signal from the sensor 20 is input, and the brake is automatically activated when the vehicle moves during unmanned parking while the vehicle is stopped, or when the inter-vehicle distance is reduced during normal driving.

The operation of the brake fluid pressure control device configured as described above will be described. [Normal brake operation (anti-lock non-control state)]
When the driver steps on the brake pedal 1 and generates hydraulic pressure in the tandem master cylinder 2, the hydraulic pressure in the front wheel brake system is changed from the first open cut valve 4 → the open hold valve 5 → the front wheel cylinder 3 And the brake is activated. In the rear wheel brake system, the first port 12a of the self-keep valve 12 → the second port 12b → the second cut valve 11 which is open → the first port 14a of the guarantee valve 14 → the second check valve 14m in the guarantee piston 14e. → Gap 14k around piston → 2nd port 14 of guarantee valve 14
b and the first port 1 of the guarantee valve 14
4a → orifice 14n → supplied to the rear wheel cylinder 3 ′ via the hold valve 5 ′ via the second port 14b of the guarantee valve 14 to operate the brake. At this time, the third switching valve 19 is in the closed state. Since the valve body 14g provided on the guarantee piston 14e abuts on the left wall surface of the cylinder to interrupt the communication between the second port 14b and the third port 14c, the guarantee valve 14 is connected to the second port 14b of the guarantee valve 14. The communication with the third port 14c is shut off.

When the driver releases the brake pedal 1,
In the front wheel brake system, the hydraulic pressure in the wheel cylinder 3 is recirculated to the master cylinder 2 through a route reverse to that described above, and the brake is released. In the rear wheel brake system, the hydraulic pressure of the wheel cylinder 3 ′ is returned to the master cylinder 2 because the second check valve 14 m is provided.
4n only. Due to the interposition of the orifice 14n, a hydraulic pressure difference is generated between both ends of the guarantee piston 14e, and the hydraulic pressure causes the guarantee piston 14e to move rightward in the drawing to move the valve body 14g away from the wall surface, and the second port 14b of the guarantee valve 14 And the third port 14c
Communicates via the first check valve 14h in the third port 14c, and the hydraulic pressure in the wheel cylinder 3 'flows into the low-pressure accumulator 15.

When the difference in hydraulic pressure acting on the guarantee piston 14e decreases, the guarantee piston 14e returns to the initial state again, and the residual pressure in the wheel cylinder 3 'is changed to the orifice 14n in the guarantee valve 14 → the first port 14a of the guarantee valve 14 → Open second cut valve 11 → second port 12 of self-keep valve 12
b → recirculates to the master cylinder 2 via the first port 12a. In this state, the self-keep valve 1
Since the same hydraulic pressure acts on both ends of the small-diameter piston 12i in 2, the small-diameter piston 12i does not move. Each time the brake operation is released, the hydraulic pressure in the wheel cylinder 3 'is accumulated in the low-pressure accumulator 15, and this accumulated pressure is monitored by the limit switch 15f. 15f is turned on.

[At the time of anti-lock control] If the wheels tend to lock during the above-mentioned brake operation, the hold valves 5, 5 'close and the decay valves 6, 6'.
Is opened to return the brake fluid in the wheel cylinders 3 and 3 'to the anti-lock control reservoirs 8 and 23, and at the same time, the hydraulic pumps 7 and 16 are operated to pump up the brake fluid in the reservoir and to return to the master cylinder 2 to brake. The control of the hydraulic pressure is executed to eliminate the locking tendency. The control mode of the hold valves 5, 5 'and the decay valves 6, 6' in this state is the same as that of the conventional antilock control.

At the time of the anti-lock control, in the front-wheel anti-lock control modulator, the liquid discharged from the front-wheel hydraulic pump 7 also flows into the damper 9, and as a result, the damper 9
By the function, kickback of the brake pedal can be reduced. In the rear wheel anti-lock control modulator, the discharge liquid of the rear wheel hydraulic pump 16 is stored in the low-pressure accumulator 15 while passing through the check valve 22 → the guarantee valve 14 → the second cut valve 11 → the self-keep valve 12. Reflux to master cylinder 2.

[At the time of automatic brake operation] As an example, an automatic brake control when the vehicle moves on a slope due to a weak pulling force of the parking brake during unmanned parking will be described. [Pressure increase] When the vehicle is stopped unattended, the parking brake is applied, the clutch pedal is not operated, the gear is in neutral, and the sensors detect that the vehicle speed has exceeded a predetermined value. The (ECU) issues a command to operate the automatic brake as follows. When an automatic brake operation command is issued, first, the second cut valve 1
1 is closed, and after a slight time difference ΔT, the second switching valve 18 opens the flow path and the motor for driving the hydraulic pump is started, so that the hydraulic pump 21
Operates.

As a result, the hydraulic pressure in the low-pressure accumulator 15 is increased by the second switching valve 18, the check valves 21 c and 21 d in the pump 21, and the first and second valves of the guarantee valve 14.
It is transmitted to the rear wheel cylinder 3 'promptly through the ports 14a, 14b and the hold valve 5' to fill the brake clearance of the rear wheel brake and bring the brake operation to an initial state. Thereafter, when the hydraulic pump 21 substantially starts operating, the pressure of the liquid flowing from the low-pressure accumulator 15 is increased and discharged from the discharge port 21b, and transmitted to the wheel cylinder 3 'via the above-described route.
Increase braking force. At this time, the low-pressure accumulator 15
Is reduced to a predetermined hydraulic pressure P2, the limit switch 15f is turned on. Thus, until the motor rotates and the hydraulic pump 21 discharges the effective hydraulic pressure, the hydraulic pressure in the low-pressure accumulator 15 is directly applied to the wheel cylinder 3 ′.
Responsiveness is improved. When the automatic brake is activated, the display lamp L in the driver's seat is turned on.

Then, the wheel cylinder pressure becomes a predetermined value P3
In the rear wheel brake system, the second cut valve 11 and the second switching valve 1
8, the second cut valve 11 is opened,
The second switching valve 18 is closed, and the driving of the motor is stopped. In this state, in the self-keeping valve 12, since the hydraulic pressure is acting on the fourth port 12d, the small-diameter piston 12i and the self-keeping piston 12f are moved leftward in the figure by this hydraulic pressure to move the valve body 12g. close. The second port 12b and the first port 12a of the self-keep valve 12
And the brake fluid in the wheel cylinder 3 ′ does not flow back to the master cylinder 2 even if the second cut valve 11 is opened thereafter. Therefore, when the hydraulic pressure in the wheel cylinder reaches the predetermined value P3, it is not necessary to continue energizing the second cut valve 11, and the energizing time to the second cut valve 11 can be controlled within the rated time, and the power saving effect can be achieved. And the durability of the valve 11 can be increased. In order to prevent the brake fluid pumped during automatic braking from excessively pressurizing the wheel cylinder 3 'side for any reason, when the discharge fluid pressure becomes a predetermined value or more, the relief valve 19a opens and the brake fluid is discharged. Third port 1 of self-keeping valve 12
2c → master cylinder 2 via the first port 12a
Reflux.

[Depressurization] When a pressure-reducing command for the automatic brake (for example, when the parking brake is released and the brake pedal is depressed) is issued, the second cut valve 11 is closed, and after a short time difference ΔT, the second cut valve 11 is closed. The 1 switching valve 17 opens the flow path, the motor for driving the hydraulic pump is started, and the hydraulic pump 16 for the rear wheel operates.

As a result, in the rear wheel brake system, the rear wheel hydraulic pump 16 pumps up the brake fluid in the wheel cylinder 3 'through the first switching valve 17 which is open, and the low pressure accumulator 15 through the discharge port 16c. While reducing the hydraulic pressure of the wheel cylinder. Thereafter, when the hydraulic pressure of the low-pressure accumulator 15 becomes P2, the limit switch 15f is turned off, and based on the signal, the second cut valve 11 is opened and the first switching valve 17 is closed by a command from the electronic control unit, and the third switching is performed. The valve 19 is opened, and the driving of the motor is stopped.

The residual pressure in the wheel cylinder is calculated as follows: hold valve 5 '→ second port 14b of guarantee valve 14 → orifice 14n in guarantee valve 14
→ The first port 14a of the guarantee valve → the discharge port 21b of the stopped automatic brake hydraulic pump 21 →
The third switching valve 19 that has been opened → the third port 12c of the self-keep valve 12 → the flow returns to the master cylinder 2 via the first port 12a, and the brake fluid pressure is completely released. The self-keeping valve 12 is opened when the hydraulic pressure becomes P1 due to the pressure reduction during that time. Then, after a lapse of a predetermined time after the motor stops (sufficient time until the residual pressure in the wheel cylinder becomes zero), the third switching valve 19 returns to the initial closed state. The timing of opening the second cut valve 11, closing the first switching valve 17, opening the third switching valve 19, and further stopping the motor is not limited to the signal from the limit switch 15f. The valve, the valve, and the motor may be switched by detecting that the hydraulic pressure in 3 ′ has become equal to or lower than a predetermined hydraulic pressure by the pressure sensor 20 or by detecting that a predetermined time has elapsed after the operation of the motor.

At the time of traction control, for example, when a slip occurs on the right rear wheel, which is a driving wheel, when the vehicle starts, the electronic control unit ECU receives a signal from the wheel speed sensor Vw.
Is detected, first, the second cut valve 11 and the left rear wheel hold valve 5 ′ are closed.
When the switching valve 18 opens, the motor for driving the hydraulic pump is started, and the cam 24 rotates. As a result, the hydraulic pressure in the low-pressure accumulator 15 is reduced by the second switching valve 18, the check valves 21 c and 21 d in the pump 21, and the guarantee valve 1.
4 to the right rear wheel cylinder 3 'via the first and second ports 14a, 14b and the right rear wheel hold valve 5', to fill the brake clearance of the right rear wheel brake, State. Thereafter, when the hydraulic pump 21 substantially starts operating, the pressure of the liquid flowing from the low-pressure accumulator 15 is increased and discharged from the discharge port 21b, and supplied to the right rear wheel cylinder 3 'via the above-described route. The brake is applied to the right rear wheel to eliminate the slip.

At this time, the hold valve 5 'on the right rear wheel side is repeatedly opened and closed as required, and the brake pressure is controlled so as to increase relatively slowly. When the slip is resolved, the right rear wheel hold valve 5 'closes,
Thereafter, the right rear wheel decay valve 6 'is opened, and the brake fluid from the right rear wheel cylinder 3' is absorbed into the reservoir 23, and the brake pressure is reduced.

[Elimination Control of Insufficiency of Accumulator Fluid in Vehicle in Long-Term Stopping State] If the brake fluid level in the accumulator is insufficient when starting the vehicle in the long-term stopped state, The accumulator piston 15b in the accumulator 15 moves to the right in FIG. 4, and the limit switch 15f detects that the amount of liquid is insufficient. In this state, when the brake pedal is depressed and the brake switch 40 is turned on, the first switching valve 17 opens for a predetermined time according to a control flowchart described later, and the hydraulic pressure generated in the master cylinder is reduced to the first port of the self-keep valve 12. 12a → second port 12b → opened second cut valve 11 → first port 14 of guarantee valve 14
a → the second check valve 1 in the guarantee piston 14e
4m → the clearance 14k around the piston → the second port 14b of the guarantee valve 14, and the first port 14a of the guarantee valve 14 → the orifice 14n → the second port 14b of the guarantee valve 14, respectively.
The brake is supplied from the hold valve 5 'to the wheel cylinder 3' to operate. At this time, a part of the brake fluid supplied to the wheel cylinder is supplied to the accumulator via the first switching valve 17 → the second suction port 16b of the rear wheel hydraulic pump 16 → the first suction port 16a, and is stored in the accumulator. Eliminate brake fluid shortage. Further, even if the brake fluid is supplied to the accumulator for a predetermined time, if the limit switch 15f in the accumulator 15 still detects the state of insufficient fluid, it is determined that a failure has occurred, and an alarm such as a failure lamp or a failure buzzer is issued. Activate the means to notify the driver of the abnormality.

[Flowchart of Accumulator Fluid Insufficiency Elimination Control] In FIG. 7, when the program is started in step S1, the limit switch 15f of the accumulator 15 is turned off in step S2 (when the accumulator fluid pressure is insufficient, the limit switch is turned off. Become)
Is determined, and if it is off, the process proceeds to step S3 to determine whether the brake is depressed (whether the brake switch 40 is turned on). When it is detected in step S3 that the brake is depressed, the process proceeds to step S4, where the first switching valve (solenoid valve) 17 is opened, and then proceeds to step S5, where the counter is incremented by one, and furthermore, the process proceeds to step S5.
At 6, it is determined whether or not the counter has reached a predetermined number N.
If the limit switch is turned on in step S2 before the counter reaches N, the process proceeds to step S9, and if the limit switch is off in step S2, the process proceeds to step S9.
When the brake is released in step 3, the program proceeds to step S9, and the program ends. In step S6, the counter is set to N.
Then, in step S7, it is determined that a failure has occurred in the hydraulic pressure replenishment system for the accumulator 15, and in step S8, a failure lamp is turned on to issue a failure alarm to the driver. In other words, when the counter exceeds N, the replenishment of the hydraulic pressure to the accumulator does not end while the opening time of the solenoid valve is longer than the predetermined time, so it is determined that there is a problem in the brake circuit and the failure is determined. Turn on the fault lamp.

It should be noted that the various sensors described in the above embodiment and the manner of processing their signals are not features of the present invention, and various known sensors and signal processing means can be applied to the braking force control device according to the present invention. .

[0038]

As described above in detail, according to the present invention, 1) if the brake fluid in the accumulator is insufficient when the vehicle is started, the driver is notified by an alarm device that the amount of the accumulator fluid is insufficient. I can let you know. 2) When the accumulator fluid level is insufficient, the brake fluid can be immediately supplied to the accumulator by using the fluid pressure generated in the master cylinder by the first brake operation, and even if the vehicle has been stopped for a long time, Sufficient pressure accumulation in the accumulator is enabled. 3) Since the hydraulic pressure of the accumulator 15 accumulated when the brake is released can be immediately transmitted to the wheel cylinder 3 'upon the start of the automatic brake control, the brake operation with good responsiveness despite the operation delay of the hydraulic pump. Is obtained. 4) Since the low-pressure accumulator 15 can be used, the size and weight of the device can be reduced, and the cost can be reduced. And the like.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a braking force control device having an automatic braking function according to an embodiment.

FIG. 2 is an enlarged sectional view of a self-keeping valve 12 in the braking force control device.

FIG. 3 is an enlarged sectional view of a guarantee valve 14 in the brake force control device.

FIG. 4 is an enlarged sectional view of a low-pressure accumulator 15 in the brake force control device.

FIG. 5 is an enlarged sectional view of a hydraulic pump in the brake force control device.

FIG. 6 is a configuration diagram of an electronic control device in the brake force control device.

FIG. 7 is a flowchart of an accumulator liquid amount shortage elimination control.

[Explanation of symbols]

 Reference Signs List 1 brake pedal 2 master cylinder 3, 3 'wheel cylinder 4 first cut valve 5, 5' hold valve 6, 6 'decay valve 7 front wheel hydraulic pump 8 front wheel anti-lock control reservoir 9 damper 11 second cut valve 12 Self-keeping valve 13, 32 Pipe line 14 Guarantee valve 15 Low pressure accumulator 16 Rear wheel hydraulic pump 17 First switching valve 18 Second switching valve 23 Rear wheel anti-lock control reservoir 20 Pressure sensor 21 Automatic brake hydraulic pump

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toru Sekine F-term (reference) 3D046 BB01 BB17 BB28 BB29 CC02 HH16 LL23 LL25 LL29 LL30 LL37 in Akebono Brake Industry Co., Ltd. 19-5, Koamicho, Nihonbashi, Chuo-ku, Tokyo LL41 LL43 LL46 LL47 MM08

Claims (3)

[Claims] An accumulator (1) is provided by a hydraulic pump (21).
5. A brake force control device having an automatic brake function capable of pumping the brake fluid pressure in 5 and supplying the fluid pressure from the accumulator to the wheel cylinder 3 'depending on the state of the vehicle and automatically operating the brake. The accumulator 15 includes a liquid amount detecting means and is connected to the wheel cylinder 3 'via a normally-closed switching valve 17. When the liquid amount detecting means detects that the accumulator liquid amount is equal to or less than a predetermined value, the brake is applied. A brake force control device characterized in that the switching valve (17) is opened during operation and a part of the brake fluid pressure supplied to the wheel cylinder (3 ') is supplied to the accumulator (15). 2. The braking force according to claim 1, wherein said accumulator is provided with alarm means capable of detecting that the amount of liquid in said accumulator has dropped below a predetermined value and issuing an alarm. Control device. 3. An anti-lock control hydraulic pump is provided separately from the hydraulic pump. The anti-lock control hydraulic pump switches the hydraulic pressure from the wheel cylinder during the anti-lock control. The braking force control device according to claim 1 or 2, wherein the pressure can be pumped up through the valve and accumulated in the accumulator.