JPS62275864A - Braking force holding device - Google Patents

Abstract

PURPOSE:To ensure the hold of a vehicle stop condition continuously by interrupting a hydraulic circuit communicated with a wheel cylinder while increasing the pressure in the wheel cylinder when a vehicle is in a stop condition continuously. CONSTITUTION:Based on outputs from a brake operation detecting means M3, a vehicle stop condition detecting means M4, and a vehicle start condition detecting means M5, when the vehicle is judged by a judging means M6 to have been not in a start condition but in a stop condition continuously for more than a predetermined time with a brake pedal actuated, an ignition command is outputted from a control means M7 to an interrupting means M1. This causes a hydraulic circuit communicating a master cylinder with a wheel cylinder to be interrupted, thereby holding a braking condition. And a command to increase the pressure in the wheel cylinder is simultaneously outputted to a pressure increasing means M2 from a pressurizing means M8 accompanied with an output from the interruption command.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention Purpose of the Invention [Industrial Field of Application 1 The present invention is effective for maintaining a stopped state in a vehicle such as an automobile by operating the brake pedal - times. This invention relates to a braking force holding device.

[Prior Art] Conventionally, a technique is known in which, for example, in a car or the like, once a brake pedal is operated to stop the vehicle, the vehicle remains stopped without operating the brake pedal until the vehicle starts moving again. As such a technique, for example, Japanese Patent Application Laid-open No. 1983-
112026 and the like have been proposed. In other words, a suction plate and an electromagnet that attracts it are provided, one of which is fixed to the vehicle body, and the usage is linked to the brake pedal, so that the two move relative to each other according to the movement of the brake pedal. The electromagnet is slidably mounted, and current is applied to the electromagnet to keep the brake applied only when the vehicle is stopped.゛ [Problems to be Solved by the Invention] By the way, if the braking force is maintained using a braking means for acceleration slip control that is provided in advance in the vehicle, a simple structure can be achieved without providing a dedicated device etc. It is possible to maintain braking force. As such an improved technique, for example, the applicant of the present application has proposed a "braking force holding device" (patent application filed on May 6, 1985).

However, the braking means for acceleration slip control as described above is necessary because it applies braking force only to the driving wheels. Therefore, in a device like the above (above), the braking force acting on the driving wheels is maintained in addition to the braking force generated when the brake pedal is operated, but the braking force acting on the idle wheels is maintained. It is lost when the brake pedal stops operating. For this reason, it has been found that the braking force that can be maintained is less than the total braking force generated at each wheel of the vehicle due to the operation of the brake pedal, and the above-mentioned improved technique is still not sufficient.

SUMMARY OF THE INVENTION An object of the present invention is to provide a braking force holding device that can effectively utilize braking means for acceleration slip control to maintain sufficient braking force.

Effects of the Invention [Means for Solving the Problems] The present invention, which was made to solve the above problems, provides a master cylinder that generates hydraulic pressure according to the amount of operation of the brake pedal, as illustrated in FIG. A shutoff means M1 that shuts off a hydraulic circuit that communicates with a wheel cylinder that applies braking force to a drive wheel according to an external command, and at least the above-mentioned shutoff means M
1 interrupts the hydraulic circuit, pressure increasing means M2 increases the pressure in the wheel cylinder according to an external command; brake operation detecting means M3 detects the operation state of the brake pedal; Stop state detection means M4 for detecting a stop state; Start state detection means M5 for detecting a start state of the vehicle; Brake operation detection means M3; Stop state detection means M4
Based on the detection result of the starting state detection means M5, the vehicle is stopped due to the operation of the brake pedal. a determining means M6 for determining whether or not the vehicle is in a continuous stopped state for a predetermined time or longer and is not in a starting state; a control means M7 for outputting a command to the cut-off means M1 to cut off the air pressure; Pressure means M8
The gist of this invention is a braking force retention device characterized by the following.

The blocking means M1 blocks communication between the mask cylinder and the wheel cylinder of the drive wheel.

For example, it can be realized by a two-point, two-position solenoid valve that switches from a communication state to a cutoff state when excited.

Alternatively, it may be a switching valve driven by hydraulic pressure, for example. Note that it is preferable to configure the valve as described above to also serve as a cutoff valve used for acceleration slip control, for example, since there is no need to provide a valve dedicated to retaining braking force.

The pressure increasing means M2 increases the pressure in the wheel cylinder of the drive wheel at least when the interrupting means M1 interrupts the hydraulic circuit.

For example, this can be realized by a capacity control valve that receives control hydraulic pressure from the outside and changes its capacity.
It may be a switching valve or the like that connects a hydraulic circuit from a hydraulic source to a wheel cylinder of a driving wheel. It should be noted that it is preferable that the above-mentioned valve be configured to be used as a capacity control valve used for acceleration slip control, for example, because the device configuration will be simplified.

The brake operation detection means M3 is for detecting the operation state of the brake pedal. For example, this can be realized by a brake switch that outputs a signal when the brake pedal is operated.

The stopped state detection means M4 detects the stopped state of the vehicle. For example, it can be configured by a vehicle speed sensor that detects the speed of the vehicle relative to the road surface.

Further, for example, the vehicle speed may be detected based on the rotational state of the wheels.

The starting state detection means M5 is for detecting the starting state of the vehicle. For example, it can be realized by a throttle position sensor that detects the throttle valve opening. For example, the switch may be a switch that detects the operating state of the accelerator pedal, such as an idle switch whose signal changes with the operation of the accelerator pedal.

The determining means M6 is necessary to determine whether the vehicle is in a continuous stopped state in which the vehicle has been in a stopped state due to brake pedal operation for a predetermined time or more and is not in a starting state.

The 1iIIv1 means M7 outputs a command to shut off the shutoff means M1 when the vehicle is continuously stopped.

The pressurizing means M8 outputs a command to the pressure increasing means M2 to increase/JD the pressure in the wheel cylinder of the drive wheel in response to the output of the cutoff command from the control means M7.

The determination means M6, the control means M7 and the pressurizing means M8 are
For example, it can be realized by a logic circuit with each independent disk and one note. For example, starting with the well-known CPU, R
It may be configured as a logic operation circuit together with OM, RAM, and other peripheral circuit elements, and may implement each of the above means according to a predetermined 98-filling procedure.

[Function] As illustrated in FIG. 1, the braking force holding device of the present invention has the following features:
Brake operation detection means M3, stopped state detection means M4
Based on the detection results of a3 and the starting state detecting means M5, when the determining means M6 determines that the vehicle is in a continuous stopped state where the vehicle has been in a stopped state due to brake pedal operation for a predetermined time or more and is not in a starting state. The control means M7 outputs a command to the cutoff means M1 to cut off the hydraulic circuit from the master cylinder to the wheel cylinder of the drive wheel, and in response to the cutoff command, the pressure increase means M8 causes the pressure increase means M2 to cut off the hydraulic circuit from the master cylinder to the wheel cylinder of the drive wheel. touch to output a command to increase the pressure inside.

When the V rope is determined to be in a continuous stopped state, the pressure inside the wheel cylinder that applies braking force to the drive wheels is increased from the pressure generated when the brake pedal is operated and is maintained. be.

Therefore, the braking force holding device of the present invention acts on the drive wheels.

By increasing and maintaining the braking force, the system works to maintain sufficient braking force to stop the vehicle by controlling the drive wheels. The technical problems of the present invention are solved by each component of the present invention acting as described above.

[Embodiment] Next, a preferred embodiment of the present invention will be described in detail with reference to the drawings. FIG. 2 shows a system configuration of a braking force holding device that is an embodiment of the present invention. As shown in the figure, the braking force holding device 1 has a mask cylinder 3 that generates hydraulic pressure according to the amount of operation of the brake pedal 2, and applies braking force to left and right rear wheels 4 and 5, which are drive wheels. It is constructed by connecting the left and right rear wheel cylinders 6.7 with a hydraulic circuit.

The hydraulic circuit is provided with a proportional valve 8, a first solenoid valve 9 and a check valve 10 arranged in parallel, and a control valve 11 for acceleration slip control.

Further, between the control input port 11a of the acceleration slip control capacity control valve 11 and the hydraulic power source 12, there is a second solenoid valve 13, which is a 3-bot, 2-position solenoid valve. A third solenoid valve 14, which is a valve, is also provided.

During the h0 speed slip control, the first solenoid valve 9 is energized and switched to the position shown on the right m11 in FIG. Cut off. At this point, the acceleration slip control volume control valve 11 changes into the following three states by a combination of energization and de-energization of the second solenoid valve 13 and the third solenoid valve 14 communicating with the control input port 11a. In other words, (1
) Communication state between the hydraulic pump 12a and the accumulator 12b and the control input port 11a, (2) Hydraulic source 1
2 and control input port 1'la; (3) communication state between reservoir 2C and control input port 11a;

Therefore, the acceleration slip control performance control valve 11 operates as follows in response to the above three states.

That is, a control hydraulic chamber 1 having a control input port 11a
The volume of the control hydraulic element 11G changes as the pressure inside 1c is increased (1), held (2), and reduced (3), and the piston 11d resists the bias of the spring 11e to move as shown in FIG. It moves to the right or to the left due to bias. As a result, hydraulic pressure is supplied from the output capo 1-11f of the brake hydraulic pressure ff11b to the left and right rear wheel cylinders 6.7. As a result, the pressure in the left and right rear wheel cylinders 6.7 is increased (1), maintained (2>), and reduced (3>).

In addition, when the braking force is maintained, the first solenoid valve 9
is excited and switches to the position shown on the right side of Fig. 2, and the cylinders 6 and 7 move from the mask cylinder 3 to the left and right rear wheel cylinders 6 and 7.
The hydraulic circuit leading to is cut off. In this case, the pressure in the left and right rear wheel cylinders 6.7 is increased by the transmission of the pressure generated in the mask cylinder 3 as the brake pedal 2 is operated. Therefore, the first solenoid valve 9 interrupts the hydraulic circuit and maintains the increased pressure. Therefore, once the brake pedal 2 is operated, the braking force is maintained even if the operation is not continued.

Roughly speaking, the pressure in the control hydraulic element 11C of the acceleration slip control capacity control valve 11 is increased (1
) or maintained (2), the pressure in the left and right rear wheel cylinders 6.7 is increased (1) or maintained (2). In this way, the retained braking force is increased as required.

The braking force holding device 1 includes a brake switch 21 that outputs a brake switch signal that changes to a binary state of ON and OFF depending on whether or not the brake pedal 2 is operated, and a vehicle speed sensor that detects the vehicle speed. The sensor 22 is turned on depending on whether or not the parking brake is operated (ON>
The parking brake switch 23 outputs a parking brake switch signal that changes to a binary state of , OFF (OFF>), and the throttle position sensor 24 outputs a signal according to the opening degree of the thrower 1 to the rear valve. Each of the above switches can be drawn. and sensor 1] are input to an electronic control unit (hereinafter simply referred to as ECU).

In addition, the ECU 3O has the above-mentioned first to third solenoid valves 9.
．． 13,14. and drives and controls the pump drive motor 12d.

r=cU 30 is a CPU 30a and a ROM 30b.

It is configured as a logic operation circuit centered around a RAM 30C, and has an input section 30e and an output section 30f via a common bus 30d.
is connected to perform input/output with the outside.

Next, the braking force holding process executed by the ECU 3O will be explained based on the flowchart of FIG. 3. This braking force holding process is repeatedly executed at predetermined time intervals after the ECU 3O is started. First, in step 100, the vehicle speed sensor 4
) Based on the detection signal of 22, the vehicle speed is ○ [Km/h],
Also, based on the detection signal of the brake switch 21, it is determined whether the brake switch signal has been in an ON state for T seconds or more. If the judgment is affirmative, the process proceeds to step 110, while if the judgment is negative, the process proceeds to step 170. In step 110, which is executed when it is determined that the vehicle is stopped and the brake pedal is being operated for T seconds or more, the parking brake switch signal output from the parking brake switch 23 is turned off (OF ).

If it is determined that 1z is positive, the process proceeds to step 120, whereas if it is negative, the process proceeds to step 170.

In step 120, which is executed when it is determined that the parking brake is not operated, it is determined whether or not the thrower 1 to rear valves are fully open based on the detection signals of the thrower 1 to position sensor 24. If the determination is affirmative, the process proceeds to step 125, while if the determination is negative, the process proceeds to step 170. In step 125, which is executed when the thrower valves 1 to 1 are fully open, the first
It is determined whether or not the solenoid valve 9 is activated (a (ON>). If the vehicle is in a stopped state for one continuous period and the braking force is not yet maintained by the operation of the first solenoid valve 9, the process proceeds to step 130. On the other hand, if the braking force is already maintained by the operation of the first solenoid valve 9, the process returns to step 110.In step 130, it is assumed that the vehicle is in a continuous stopped state and not in a starting state. In order to maintain the braking force, a process is performed in which the first solenoid valve 9 is energized (ON).As a result of this process, the hydraulic circuit from the mask cylinder 3 to the left and right rear wheel cylinders 6, 7 is cut off. , the pressure in the left and right rear wheel cylinders 6.7 is maintained immediately in response to the brake pedal operation.Next, the process proceeds to step 140, where the second solenoid valve 13 is turned ON for 4 hours. Excitation (ON) processing is performed. Through this processing, the hydraulic pump 12a, the accumulator 12b, and the control input port '1 of the acceleration slip control capacity control valve ]1 are
1a, and the pressure in the left and right rear wheel cylinders 6.7 is increased over a period of time TON. In the following step 150, the second solenoid valve 13 is de-energized (OF
F>, and the third solenoid valve 14 is energized (Of'L
), the process returns to step 110 above. Through this process, the hydraulic power source 12 and the control input capo 1-118 of the acceleration slip control capacity control valve 1 are cut off, and the left
The pressure in the right rear wheel cylinder 6.7 is maintained at the pressure increased in step 140 above.

On the other hand, if a negative determination is made in step 100 above,
Proceed to step 170. In step 170, which is executed when the vehicle is not in a stopped state by operating the brake pedal, the first to third solenoid valves 9, 13, and 14 are de-energized (OFF>), and then - water control is performed. End the power retention process.

Also, if a negative determination is made in step 110, the process goes through step 170 and ends the water braking force holding process. In this case, when the parking brake is operated, the hydraulic circuit is brought into communication as it is no longer necessary to maintain the braking force. Therefore, the braking force that was being held is immediately released.

Note that if a negative determination is made in step 120, that is, if the throttle valve is heard after the vehicle has stopped and it is determined that the vehicle is in a starting state, step 170 is also executed.
After that, the -setting power holding process is ended. Thereafter, this braking force holding process is repeatedly executed every time the execution condition is satisfied.

In this embodiment, the first solenoid valve 9 is connected to the blocking means M1, the acceleration slip control capacity control valve 11, the hydraulic pressure source 12, the second solenoid valve 13, the third solenoid valve 14, and the pressure increasing means M2 to the brake switch 2. ] to the brake operation detection means M3, the vehicle speed sensor 22 to the stop state detection means M4, and the vehicle speed sensor 22 to the stop state detection means M4.
and the starting state detection means M5, respectively. Also, ECU
Behind the 3O execution process (steps 100, 120>
(step 130) functions as the determining means M6, (step 130) functions as the control means M7, and (step 140) functions as the pressurizing means M8, respectively.

As explained above, in this embodiment, when the stopped state due to the operation of the brake pedal 2 continues for T seconds or more, the parking brake is not operated, and the slot 1 to 1 valves are closed and the starting state is not in progress, 1 Solenoid valve 9 shuts off the hydraulic circuit and the left and right rear wheel cylinders 6
．． While maintaining the pressure in the left and right rear wheel cylinders 6.7, the acceleration slip control capacity control valve 11, hydraulic power source 12, and second and third solenoid valves 13.14 are operated to reduce the pressure in the left and right rear wheel cylinders 6.7. is configured to increase

Therefore, the braking force acting on the rear wheels 4 and 5, which is necessary for the driving wheels, is increased and maintained higher than the braking force transmitted by operating the brake pedal 2, so sufficient braking force can be obtained and the braking force applied to the rear wheels 4 and 5 is increased and maintained. By effectively utilizing the acceleration slip control device, highly reliable braking force retention can be achieved.

In addition, by increasing the pressure in the left and right rear wheel cylinders 6.7, sufficient braking force can be obtained (q), thereby improving stability when the vehicle is stopped by maintaining the braking force.

Note that the time TON for exciting the second solenoid valve 13
It is preferable to select an optimum value in consideration of the time required for the pressure to increase to a level sufficient to compensate for the loss of the braking force acting on the idler wheels.

Furthermore, the braking force can be maintained by using the existing acceleration slip control/capacity control valve 11, hydraulic pressure source 12, and first to third solenoid valves 9, 13, and 14. Since a dedicated braking device is not required, the device configuration is simple and the space inside the vehicle can be used effectively.

In addition, if there is no need to maintain braking force, the first to third
In order to immediately release the braking force held by de-energizing (OFF) the solenoid valve 9.13.14, do not continue to apply unnecessary pressure to the hydraulic circuit or the left and right rear wheel cylinders 6.7. Therefore, the durability of the device is also improved.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments in any way, and it goes without saying that it can be implemented in various forms without departing from the gist of the present invention.

Effects of the Invention As detailed above, the braking force holding device of the present invention allows the determining means to determine that the vehicle is in a continuous stopped state based on the detection results of the brake operation detecting means, the stopped state detecting means, and the starting state detecting means. When the determination is made, the control means outputs a cutoff command to the cutoff means, and in response to the output of the cutoff command, the pressurization means outputs a pressure increase command to the pressure increase means.

Therefore, in addition to the total braking force generated on each wheel when the brake pedal is operated, the braking force acting on the idle wheels that disappears when the brake pedal is released is compensated for by increasing and maintaining the braking force acting on the driving wheels. Therefore, the excellent effect of improving the reliability of braking force retention with a simple configuration is achieved.

Moreover, since the above effect allows the vehicle to be reliably maintained in a stopped state, stability during continuous stopping is also improved.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram illustrating the contents of the present invention, FIG. 2 is a system configuration diagram of an embodiment of the present invention, and FIG. 3 is a flowchart A--to showing the control thereof. Ml...Shutoff means M2...Pressure increase means M3...Brake operation detection means M4...Stop state detection means M5...Start state detection means M6...Judgment means Ml...Control means M8 ... Pressurizing means 1 ... Braking force retention 1. 'j device 9...First solenoid valve 11...Acceleration slip 1.111ffll capacity control valve 12...Hydraulic pressure source 13...Second solenoid valve 14...Third solenoid valve 21... Brake switch 22... Vehicle speed sensor 24... Throttle position sensor 30... Electronic control unit (ECU) 30 a-CPU

Claims (1)

[Scope of Claims] 1. A shutoff means that shuts off a hydraulic circuit that communicates from a master cylinder that generates hydraulic pressure according to the amount of operation of the brake pedal to a wheel cylinder that applies braking force to the driving wheels in accordance with an external command; At least when the shutoff means shuts off the hydraulic circuit, pressure increasing means increases the pressure in the wheel cylinder according to an external command; brake operation detection means detects the operation state of the brake pedal; and a vehicle. a stop state detection means for detecting a stop state of the vehicle; a start state detection means for detecting a start state of the vehicle; and a stop state detection means for detecting a start state of the vehicle; a determining means for determining whether or not the vehicle is in a continued stopped state in which the vehicle has been in a stopped state due to brake pedal operation for a predetermined time or more and is not in a starting state; and when the determining means determines that the vehicle is in a continued stopped state; a control means for outputting a command to the cutoff means to cut off the hydraulic circuit; a pressurizing means for outputting a command to the pressure increase means to increase the pressure in the wheel cylinder in response to the command output from the control means; A braking force retention device characterized by comprising: