JPS61287854A - Vehicle running control device - Google Patents

Abstract

PURPOSE:To prevent a high pressure from being applied to a hydraulic pressure supply piping, by setting a brake force for each wheel by means of a piezoelectric piston mechanism provided in each wheel cylinder. CONSTITUTION:A hydraulic pressure condition in a master cylinder 12 is monitored by hydraulic pressure sensors 19a and 19b, and when the hydraulic pressure is increased, cut valves 16a-16d are closed. Under the condition, wheel cylinder parts of control mechanisms 14a-14d of wheels are separated from master cylinder parts, and a volume of each wheel cylinder is partitioned. An electronic control unit 17 compares a depression force of a brake pedal with a hydraulic pressure in each wheel cylinder, and controls a voltage to be applied to a piezoelectric piston mechanism for adjusting the hydraulic pressure in each wheel cylinder.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to the improvement of a braking device for automobiles, etc., and in particular to an improved booster means for effectively assisting and controlling the operating force of a brake operating section. The present invention relates to a vehicle travel control device.

[Background Art] Braking devices for vehicles such as automobiles are usually configured to utilize hydraulic pressure. That is, the vehicle is equipped with a master cylinder that generates hydraulic pressure when the brake pedal is depressed, and the master cylinder transmits the hydraulic pressure generated in response to the pedal operation to the wheel cylinders set for each wheel. Then, the brake piston set in this wheel cylinder is driven to apply a braking force to a brake disc or the like set for each wheel.

In this case, the depression force of the brake pedal may be directly converted into hydraulic pressure and this hydraulic pressure may be used to drive the brake piston in the wheel cylinder, but the above depression force is made to act more effectively on the braking force. Therefore, a pedal assist device (booster) is used. This booster generates a higher hydraulic pressure at a constant rate than when the force applied to the brake pedal is directly converted into hydraulic pressure.

By using such a booster mechanism, more sufficient braking force can be ensured, especially when the road surface condition is good. However, by utilizing such hydraulic assisting means, all hydraulic piping from the master cylinder to the wheel cylinders needs to be configured as high-pressure piping. In addition, the same hydraulic pressure will now be applied to wheels with different conditions, such as the front and rear wheels and the inner and outer wheels during a turn, which will require special additional adjustment means such as a proportional valve. The configuration becomes complicated.

[Problems to be Solved by the Invention] This invention has been made in view of the above-mentioned points. In particular, it is possible to provide brakes to the wheel cylinders of each wheel without setting the hydraulic pressure supply piping to each wheel as a high-pressure piping. This system allows hydraulic pressure to be applied to the operating section to assist in operating force, so that braking force is effectively applied, and it also makes it possible to individually control the braking force that acts on each wheel. Therefore, it is an object of the present invention to provide a vehicle running control tIIl device that can more effectively improve the running stability of a vehicle.

[Means for Solving the Problems] That is, in the vehicle travel control device according to the present invention, a piezoelectric piston mechanism that is controlled to expand and contract by voltage is set in a wheel cylinder that is set for each wheel. The piston mechanism is configured to perform hydraulic pressure control by voltage control, and a hydraulic pressure detection means is set for the master cylinder, and when the brake operating section is operated and the hydraulic pressure of the master cylinder is increased, The wheel cylinder portion is divided by a cut valve, and braking force is generated by the piezoelectric piston mechanism.

[Function] In the vehicle travel control device configured as described above, when the brake operating section is operated and the oil pressure in the master cylinder increases (9), the oil pressure from the master cylinder to each wheel cylinder increases. The cut valve set in the pipe is closed, and each wheel cylinder portion is divided into sections. In this state, when the piston mechanism is controlled to extend by applying a voltage proportional to the oil pressure detected by the oil pressure detection means to the piezoelectric piston mechanism in the wheel cylinder, the oil pressure in the wheel cylinder is controlled by the piezoelectric piston mechanism. controlled, braking force is generated, and the booster function is activated. In this case, the braking force acting on each wheel is set by the piezoelectric piston mechanism set in the wheel cylinder of each wheel, so the braking force is applied to each wheel according to each condition. It is also possible to control the power settings.

[Embodiments of the invention] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration, and the hydraulic pressure of the master cylinder 12 is increased by depressing a brake pedal 11 constituting a brake operation section. From this master cylinder 12, it goes to wheel cylinders 14a and 14b set for front wheels 13a and 13b, and further to rear wheels 13c and 13d. Hydraulic pressure is supplied to the control 71 mechanisms 14c and 14d including the wheel cylinders to be set via hydraulic piping 15a to 15d, respectively. In this case, each of the above piping 158 to 15
d, cut valves 16a to 16d are set respectively, and the cut valves 16a to 16d are controlled to cut the pipes 15a to 15d, respectively, by a command from the electronic 11J all unit 17. Ru. In addition, check valves 18a to 18d are set in parallel to the cut valves 16a to 16d, respectively, to prevent oil from flowing in the direction of the master cylinder 12 of the braking mechanisms 148 to 14d. The hydraulic pressure from the master cylinder 12 is applied to each of the braking mechanisms 14a to 14d.
It is designed to be supplied directly for INII back pressure setting.

Oil pressure detection sensors 19a are provided in the output piping portions of the front wheel side oil pressure and the rear wheel side oil pressure of the master cylinder 12, respectively.
, 19b is provided, and the brake pedal 1
1 is operated, the hydraulic pressure supplied to the front wheels and the rear wheels is detected, and the detected hydraulic pressure data is supplied to the electronic control unit 17. Moreover, the oil pressure in the wheel cylinder of each of the braking mechanisms 14a to 14d of each wheel is determined by oil pressure detection sensors 20a to 20d, and these sensors 20a to 20d act on each of the wheels 138 to 13d, respectively. Braking oil pressure data is detected and supplied to the control unit 17.

FIG. 2 shows one of the braking mechanisms installed and set for each of the above-mentioned wheels, and this braking mechanism is operated by hydraulic pressure supplied through a cut valve in the brake caliper 30. The wheel cylinder 31 is configured to form a wheel cylinder 31. A brake piston 32 is installed in this wheel cylinder 31, and when the hydraulic pressure inside the wheel cylinder 31 increases and the brake piston 32 is driven, it is rotated coaxially with the wheel by the brake pads 33 and 34. A brake disc 35 is sandwiched therebetween, and the rotation of this disc 35 is braked.

A control cylinder 36 is further provided so as to be set in series with the wheel cylinder 31. A piezoelectric piston mechanism 37 is set within the control cylinder 36, and the hydraulic pressure in the oil chamber 38 of the wheel cylinder 31 is controlled by this piezoelectric piston mechanism 37.

The piezoelectric piston mechanism 37 is configured such that a first piezoelectric element group 41 configured by laminating a plurality of thin plate-shaped piezoelectric elements is set between a first substrate 39 and a second substrate 40. This is what has become. In this case, the first substrate 39 is set to have a smaller area than the second substrate 40, and the first substrate 39 is opened to the wheel cylinder oil chamber 38. Then, the second substrate 4
0 and the wall portion of the control cylinder 36 on the wheel cylinder 31 side, a second piezoelectric element group 42 is set. The chamber 44 is set to be supplied with hydraulic pressure from the master cylinder 12 .

That is, in the braking device configured as described above,
In a running state where normal braking operation is not performed, the cut valve 18
a to 16d are opened, and the oil pressure of the wheel cylinder 31 of each of the braking mechanisms 148 to 14d is set to a low state. When the brake pedal 11 is depressed, the oil pressure in the master cylinder 12 increases, and this oil pressure is supplied to the braking mechanisms 14a to 14d. In this case, the oil pressure state of the master cylinder 12 is monitored by the oil pressure detection sensors 19a and 19b. For example, when the oil pressure of the master cylinder 12 rises to the state of pressure Ps shown in FIG. Detected at 17. In this oil pressure increase detection state, the control unit 17 controls the cut valves 16a to lad.
Give a command to close it. That is, in this state, the braking mechanism 1 of each wheel 13a to 13d
The wheel cylinder 31 section from 48 to 14d is the cut valve 1
The wheel cylinders 6a to 16d are separated from the master cylinder 12 so that the volume of each wheel cylinder 31 is defined.

That is, when the cut valves 168 to 16d are closed, the wheel cylinder 31 of the braking mechanism shown in the second cause
The volume of the oil chamber 38 is set to be constant,
The pressure in the oil chamber 44 of the control cylinder 36 is now set by the master cylinder 12.

In this case, the piezoelectric piston mechanism 37 is set to be reduced without applying a high voltage to the first piezoelectric element group 41,
Further, a high voltage is applied to the second piezoelectric element group 42 so that it is set to expand. That is, the first substrate 39 of the piezoelectric piston mechanism 31 that is open to the wheel cylinder 31 is set to be the most retracted from the wheel cylinder 31 direction.

In this state, the electron 1lIIIl unit 17 is
The brake pedal depression force is detected based on the detection information from the oil pressure detection sensors t9a and 19b, and this depression force detection signal is compared with the detection signal from the wheel cylinder oil pressure detection sensors 20a to 20d of each braking mechanism 14a to 14d,
First and second piezoelectric element groups 4 of piezoelectric piston mechanism 37
1 and 42 are controlled.

Specifically, when the oil pressure of the master cylinder 12 increases, the voltage applied to the first piezoelectric element group 41 is increased, the voltage applied to the second piezoelectric element group 42 is decreased, and the voltage applied to the second piezoelectric element group 42 is decreased. The base plate 39 of the wheel cylinder 31 is driven in the direction of protruding into the wheel cylinder 31. The hydraulic pressure of the wheel cylinders 12 is increased in response to the increase in the hydraulic pressure of the master cylinder 12, and the braking force is increased. In this case, the detection sensors 20a to 20
When the hydraulic pressure of the master cylinder 12 increases as shown by the chain line in FIG. 3, the hydraulic pressure of the wheel cylinder 31 is increased as shown by the solid line in FIG. .

That is, the oil pressure of the master cylinder 12 is Pb indicated by 8.
When the state shown by is reached, the oil pressure of the wheel cylinder 31 is controlled to be multiplied by a certain ratio to reach Pa shown by A. Then, booster control of the braking force is executed.

Therefore, in such a travel control device, there is no need for particularly high-pressure piping in the hydraulic piping from the master cylinder 12 to the wheel cylinder 31 during booster control, and moreover, the high-speed response of the piezoelectric element is effectively utilized. Braking control will now be executed in the state where the vehicle is being used.

When such dynamic control is executed, each wheel 13a
The oil pressure state of the wheel cylinder 31 is detected corresponding to each of 13d to 13d, and this detected value and the master cylinder
The piezoelectric piston machine 4IlI37 of each braking mechanism 14a to 14d is controlled by comparing with the detected oil pressure value.

Therefore, it is possible to perform braking force control according to the load conditions of the wheels 13a to 13d, which vary depending on the running state of the vehicle.

For example, the boost ratio of the braking force for the front and rear wheels can be adjusted and controlled depending on the difference in the load conditions of the front and rear wheels, and in the case of turning, the boost ratio can be adjusted and set according to the load conditions of the inner and outer wheels. can.

Here, in the control unit 17, signals such as a signal from a speed sensor that detects the running state of the vehicle, a detection signal from a yaw rate sensor that detects the state of lateral shaking, a steering detection signal, etc. are supplied and set as appropriate. Therefore, it is effective to perform boost ratio control of the braking force for each wheel based on these detection signals.

[Effects of the Invention] As described above, the vehicle travel control device according to the present invention is capable of executing boost control that increases and controls the hydraulic pressure of the master cylinder for each wheel installed on the vehicle. Therefore, there is no need for high-pressure piping especially for boost control, and boost control that effectively utilizes the high-speed operation characteristics of the piezoelectric element can be performed. In addition, the boost ratio in the case of such boost tlllIO is not specified as a fixed value, and control such as reduction of the boost ratio can be executed in relation to the master cylinder oil pressure and in response to the driving conditions. The braking force that best suits the running conditions of the vehicle is set, for example, for each wheel, which is highly effective in improving the stable running characteristics of the vehicle.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a braking system for explaining a vehicle travel control device according to an embodiment of the present invention, and FIG. 2 is a cross-sectional configuration showing one of the braking mechanism parts used in the above embodiment. 3 are diagrams for explaining the boost ratio of the above embodiment. 11...Brake pedal, 12...Master cylinder, 13a to 13d-...Wheel, 14a to 14d-
...Brake mechanism, 16a-16d...Cut valve, 17.
...°Electronic control unit, 18a to 18d...Check valve, 19a, 19b, 20a to 20d...
Oil pressure detection sensor, 31... wheel cylinder, 32...
... Brake piston, 36 ... Control cylinder, 37
...Piezoelectric piston mechanism. Applicant's agent Patent attorney Takehiko Suzue Figure 2, Figure 351

Claims (1)

[Scope of Claims] A piezoelectric piston mechanism that is set in a wheel cylinder that applies a braking force to each wheel, and that controls the hydraulic pressure in the wheel cylinder by controlling expansion and contraction using voltage; and a brake. cut valves respectively set in hydraulic passages that supply hydraulic pressure from the master cylinder to each of the wheel cylinders in response to the operation of the operating section; means for detecting the hydraulic pressure set by the brake operating force of the master cylinder; means for closing the cut valve in a state in which an increase in oil pressure in the master cylinder is detected by the means, and controlling a voltage applied to the piezoelectric piston mechanism in response to a detected value of the oil pressure detection means, The vehicle running control is characterized in that the hydraulic pressure in the wheel cylinder divided by the cut valve is controlled by a piezoelectric piston mechanism in accordance with the detected hydraulic pressure value, so that brake operation force is assisted and applied. Device.