JPS61287849A - Vehicle running control device - Google Patents

Abstract

PURPOSE:To effectively eliminate a skid condition, by providing a cut valve in a hydraulic piping for a wheel cylinder and providing a piezoelectric piston mechanism expanding and contracting to control the wheel cylinder. CONSTITUTION:When a brake pedal 11 constituting a brake operation means is operated, a hydraulic pressure in a master cylinder 12 is increased and is applied through a hydraulic piping to a braking mechanism. Cut valves 16a-16d to be controlled by a command from an electronic control unit are provided in the hydraulic piping. A wheel cylinder 31 is formed in a brake caliper 30, and a control cylinder 36 is formed in connection with the wheel cylinder 31. A piezoelectric piston mechanism 37 is provided in the control cylinder 36, and is adapted to expand and contract to control a hydraulic pressure in an oil chamber 38 defined in the wheel cylinder 31.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to the improvement of a brake control device for automobiles, etc., and in particular to assisting and controlling the operating force of the brake operating section and also performing skid control. The present invention relates to a vehicle travel control device using a piezoelectric element.

[Background Art] Braking devices used in automobiles and the like are usually configured to use hydraulic pressure. That is, the vehicle is equipped with a master cylinder that generates hydraulic pressure when the brake pedal is depressed, and the hydraulic pressure generated by the master cylinder is supplied to the wheel cylinders set for each wheel. Then, a brake piston set in this wheel cylinder is driven, and a braking force is generated by 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 mechanism generates a higher hydraulic pressure at a fixed ratio than when the force on 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 using such a booster mechanism, all hydraulic piping from the master cylinder to the wheel cylinders must 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 turning, which will require special additional adjustment means such as blow-off valves, and the overall The configuration becomes complicated.

[Problems to be Solved by the Invention] This invention has been made in view of the above-mentioned points, and in particular, the piping w4 structure for each wheel. ! There is no need to make it complicated, and for the wheel cylinder set for each wheel,
Hydraulic pressure is supplied in accordance with the conditions of each wheel, and in the event of a skid, braking force can be controlled to effectively eliminate the skid.
It is an object of the present invention to provide a vehicle running control device that can ensure a stable running state.

[Means for Solving the Problems] That is, in the vehicle running ill-tel device according to the present invention, the hydraulic pressure is set from the master cylinder to each wheel cylinder of a braking mechanism set to each wheel. A cut valve is set for the piping, and a piezoelectric piston mechanism whose expansion and contraction are controlled by controlling the voltage applied to the wheel cylinder is set. In addition, a switching valve including a check valve function is set in parallel to each of the cut valves, and when a skid occurs on a wheel, the switching valve corresponding to that wheel is closed and the piezoelectric piston mechanism is controlled. The purpose is to ensure that

[Function] In the travel control device configured as described above, when the brake operating section is operated and the hydraulic pressure of the master cylinder is increased, the cut valve is closed and the wheel cylinder section is set, and the piezoelectric piston mechanism is controlled to extend, and a braking force that assists the operating force comes into play. and,
When a skid occurs under such braking conditions, the switching valve corresponding to the wheel that caused the skid is closed, and the piezoelectric piston mechanism is controlled to reduce, so that the braking force of the wheel that caused the skid is reduced. , which will prevent skids. In this case, the above-mentioned pedal force assisting and skid inhibiting operations are performed by a piezoelectric piston mechanism whose speed is controlled by controlling the applied voltage. Since power control is performed and this piezoelectric piston mechanism is set for the wheel cylinder, there is no need to pay special consideration to the hydraulic piping.

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

FIG. 1 shows its configuration. When a brake pedal 11 constituting a brake operating section is operated, the oil pressure of a master cylinder 12 is increased. The hydraulic pressure generated by this master cylinder 12 is applied to each of the front and rear wheels 138.
Braking mechanisms 148 to 14 set to each of ~13d
d, respectively, through hydraulic pipes 15a to 15d, and cut valves 16a to 16d are respectively set to each of the pipes. The cut valves 16a to +6d are controlled by commands from the electronic control unit 17, respectively.

Further, switching valves 18a to 18d are set in parallel to each of the cut valves 16a to 16d,
Check valves 19a to 19 (I) are provided in series with the switching valves 18a to 18d, respectively, to block the flow of oil from the braking mechanisms 148 to 14d to the master cylinder 12. ~18d are also controlled by the electronic control unit 1T.

Although not explained in detail here, the electronic control unit 17 is configured by, for example, a microcomputer, and also receives a steering signal from a steering sensor 20 and a detection signal for braking control from a road/vehicle load sensor 21. , detection signals from oil pressure detection sensors 22 and 23 for the front and rear wheels of the master cylinder 12 are supplied. Moreover, for each of the brake mechanisms 148 to 14d of the wheels 13a to 13d, a hydraulic pressure detection sensor 24 of a wheel cylinder constituting this brake mechanism is used.
a to 24d are provided, and wheel speed detection sensors 25a to 25d are set to each wheel 138 to 13d, and these sensors 24a to 24d and 25a to 25d
The detection signal from is set to be supplied to the electronic control unit 11. In this electronic control unit 11, the hydraulic pressure set by the master cylinder 12 and each braking mechanism 14 are controlled.
This is to control the appropriate braking force by comparing the oil pressure set at 8 to 14d, and also to control the braking force of each wheel during turning operation and the like.

FIG. 2 shows one of the braking mechanisms 14a to 14d set for each wheel in the braking control system as described above, in which a wheel cylinder 31 is formed within a brake caliper 30. There is. This wheel cylinder 3
A brake piston 32 is set inside the brake pad 1. This brake piston 32 integrally drives a brake pad 33, and a brake disc 35 is sandwiched between it and a brake pad 34 which is fixedly set.
Braking force is applied to the wheels that rotate integrally with 4. A control cylinder 36 is further formed so as to be open and continuous with the wheel cylinder 31 . This control cylinder 36 has a piezoelectric piston mechanism 37.
is set, and this piezoelectric screw mechanism 37
The oil pressure of the first oil chamber 38 set in the wheel cylinder 31 is controlled by the expansion and contraction of the wheel cylinder 31 .

Then, the first oil chamber 38 is set to be supplied with hydraulic pressure from the cut valve. .

The piezoelectric piston mechanism 37 has first and second substrates 39
and 40, a first piezoelectric element group 41 in which a plurality of thin plate-like piezoelectric elements are stacked is interposed between the second substrate 40 and the first substrate 39 of the control cylinder 36. A second piezoelectric element group 41 in which a plurality of piezoelectric elements are stacked is interposed between the side shoulder portion and the side shoulder portion. In this case, a second oil chamber 44 is formed within the control cylinder 36 divided by the second base plate 40, and a master master is provided for this second oil chamber 44 as shown by the broken line in FIG. The hydraulic pressure from the cylinder 12 is set to be supplied. Here, this second
The area of action of the second substrate 40 with respect to the oil chamber 44 is set larger than the area of action of the first substrate 39 with respect to the first oil chamber 38 of the wheel cylinder 31.

That is, in the vehicle travel control device configured as described above, when the brake pedal 11 is depressed, the oil pressure of the master cylinder 12 changes as shown by the broken line in FIG. 3 in response to the depression force. Rise. Then, this oil pressure is detected by the oil pressure detection sensors 22 and 23, and when the detected pressure reaches ps, the electronic control unit 17 closes the cut valves 16a to 16d, and also closes each of the braking mechanisms 14a to 16d.
Control of the piezoelectric piston mechanism 37 of 14d is started.

FIG. 4 shows a flowchart explaining the flow of braking control in such electronic control unit 17.
In step 101, a brake operating force P is detected, and in the next step 102, this detected pressure P is compared with a set pressure ps. Then, in the state of rP>PS J, the process proceeds to step 103, where the cut valves 16a to 16d are closed and each braking mechanism
The volume of the wheel cylinder 31 portion from 14d to 14d is partitioned so as to be restricted to a specified state. Then, in step 104, the voltage applied to the first and second piezoelectric element groups 41 and 42 of the piezoelectric piston mechanism 37 is controlled to extend the piezoelectric piston mechanism 37, and the first oil chamber 38 of the wheel cylinder 31 is controlled to extend. The hydraulic pressure is increased to drive the brake screws 1 to 33 so that braking force is applied.

Specifically, the voltage applied to the first piezoelectric element group 41 is increased to expand it, and the voltage applied to the second piezoelectric element group 42 is decreased to shrink it, so that the first substrate 39 It is designed to be driven in the direction of protruding into the wheel cylinder 31. In this case, the second oil chamber 44 of the control cylinder 3G contains the master cylinder 1.
Since the oil pressure of No. 2 is set, the oil pressure inside the wheel cylinder 31 is increased.

In this case, the piezoelectric piston mechanism 3
The extension control state is set such that when the oil pressure of the master cylinder 12 is the pressure pb shown as B in FIG. 3, the oil pressure of the wheel cylinder 31 is set to the pressure Pa shown as A in the same figure. The extension of the piezoelectric piston mechanism 37 is controlled so that the pedal force assistance control of the ratio is executed.

That is, when the brake piston 11 is depressed, braking control is executed with the pedal force being increased. In this case, the oil pressure set in the wheel cylinder 31 is set between each of the cut valves 16a to 16d and the wheel cylinder 31 of the braking mechanism 148 to 14d of each wheel.
Since the high oil pressure is set and controlled at the 0 portion, the hydraulic piping may be configured with a sufficiently simplified configuration. Then, high-speed response control, which is a characteristic of the piezoelectric element, is executed. Further, the respective braking force at each wheel 13a to 13d is determined by the respective braking mechanism 14a.
~Oil pressure detection sensor 24a set to 14d~
Since it is controlled based on the value detected by wheel 24d, the braking force at each wheel 13a to 13d is set in an optimally balanced state. Further, based on the detection signal from the steering sensor 20, the detection signal from the road surface/vehicle load sensor 21, etc., it is also possible to control the braking force of each wheel in accordance with the running state of the vehicle.

Then, when the brake pedal 11 is released and the oil pressure detected by the oil pressure detection sensors 22 and 23 becomes lower than P, the process proceeds to step 105, and the cut valves 16a to 1
6d becomes open. Here, in such a normal braking control state, the switching valves 18a to 18d are set to an open state.

In this braking state, for example, if a slip state occurs in a certain wheel, this state will occur in each of the wheels 13a to 13d.
It is detected based on signals from wheel speed detection sensors 25a to 25d set to .

That is, as shown in FIG. 5, when the above skid condition occurs, the skid is detected in step 201. When the skid is detected in this way, the process is performed in step 202 to deal with the wheel that caused the skid. The switching valves (18a-18d) are closed. That is, even if the oil pressure of the master cylinder 12 increases, the oil pressure is not applied to the wheel cylinder 31. In this state, the process proceeds to step 203, where the piezoelectric piston mechanism 37 is controlled to reduce. , the hydraulic pressure of the wheel cylinder 31 is lowered to reduce the braking force of that wheel. In other words, since the braking force of the wheel where the slip has occurred is reduced, the state of occurrence of the slip is suppressed.
This allows skid control to be performed so that the vehicle runs stably.

[Effects of the Invention] As described above, the vehicle travel control device according to the present invention utilizes a piezoelectric element to set a boost mechanism with high-speed response without applying large hydraulic pressure to the hydraulic piping section. Therefore, braking control for the vehicle can be executed very effectively. Moreover, in this braking mechanism, the braking force acting on each wheel can be set to a state that corresponds to the braking conditions existing on each wheel in accordance with the running state of the vehicle, so that it is possible to control the stable running of the vehicle. is carried out effectively. Additionally, this braking mechanism allows skid control to be executed simultaneously, resulting in more stable driving control.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram illustrating a vehicle running control device according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing one of the braking mechanisms constituting the device, and FIG. FIG. 4 shows the relationship between pedal force and generated oil pressure in the control device. FIGS. 4 and 5 are flowcharts showing the flow of braking control by the control device, respectively. DESCRIPTION OF SYMBOLS 11... Brake pedal, 12... Master cylinder, 148-14d... Braking mechanism, 16a-16d.
...Cut valve, 17...Electronic control unit, 18a~
18d...Switching valve, 22.23.24a-24d...
- Oil pressure detection sensor, 31...Wheel cylinder, 32
...Brake piston, 36...Control cylinder, 3
7... Piezoelectric piston mechanism, 41.42... First and second piezoelectric element groups. Applicant's agent Patent attorney Takehiko Suzue Figure 2 Figure 4 Figure 5

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; Correspondingly, there are cut valves set in the hydraulic passages that supply hydraulic pressure from the master cylinder to each of the wheel cylinders, and a check valve function that is set in parallel with each of the cut valves to prevent a decrease in the hydraulic pressure of the wheel cylinders. a switching valve including a switching valve; a means for detecting an increase in oil pressure in the master cylinder due to a brake operation; and a means for closing the cut valve in a state in which the detection means detects an increase in oil pressure in the master cylinder, and applying an application to the piezoelectric piston mechanism. means for increasing the hydraulic pressure in the wheel cylinder by controlling a voltage corresponding to the master cylinder hydraulic pressure; What is claimed is: 1. A driving control device for a vehicle, comprising means for controlling the voltage of a mechanism to reduce the wheel cylinder oil pressure thereof, so that brake operation force is assisted and made to act as a braking force.