JPS60209353A - Braking device for vehicles - Google Patents

Abstract

PURPOSE:To make braking force by a brake pedal reducible, by installing a magnetic field generating device which varies viscosity of a magnetic fluid to be circulated by a pump, in case of such a braking device that infinitesimally increases or decreases a degree of braking pressure with the magnetic fluid. CONSTITUTION:In case of a braking device which generates braking force in a way of feeding a high pressure hydraulic fluid composed of a magnetic fluid being mixed with iron powder, produced from a master cylinder 2 by operation of a brake pedal 1, to a wheel cylinder 4 after regulating pressure by a braking force controlling part 3, the braking force controlling part 3 is controlled by a fluid regulating device 10. This fluid regulating device 10 consists of a magnetic fluid 11 being circulated by a pump 5 and transmitting pressure to a brake controlling part 3 with viscosity control by means of an impressed magnetic field, a magnetic field generating device 12 variably controlling viscosity of the magnetic fluid and a magnetic field controlling device 13, where a car speed signal 15 is inputted, transmitting a control signal to prevent wheels from being locked to the magnetic field generating device 12.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a braking system for a vehicle, and more particularly to a braking system for a vehicle that uses a magnetic fluid to slightly increase or decrease brake pressure. This is used in the field of anti-skid control to prevent wheel slip during braking.

[Prior art]

Under weather conditions such as rain or snow, the frictional resistance of the wheels against the road surface decreases. If a large amount of braking is applied in such a situation, the rotation prevention force of the wheels will be exceeded, causing the wheels to lock and slip, which will have a negative effect on the dynamic stability of the vehicle. In order to suppress this phenomenon, anti-skid technology automatically releases the brake pressure during the braking operation and rotates the wheels again, independently of the driver's brake pedal operation, in order to restore the contact force with the road surface. control is known.

What made this kind of control possible is the Japanese Patent Application Laid-Open No. 51-11
There is a vehicle skid control device described in Japanese Patent No. 4564. In this system, a solenoid valve is interposed in the hydraulic circuit between the master cylinder and the wheel cylinder, which converts the force applied to the brake pedal into fluid pressure, and the hydraulic pressure is controlled by opening and closing this valve in response to signals from the control command unit. . According to this, the braking speed, which decreases over time according to the force applied to the brake pedal, is separately estimated, and the estimated speed is compared point by point with the actual rotational speed of the wheels, and the solenoid valve is opened or closed based on the deviation. Braking oil pressure supplied to the wheel cylinders is adjusted. That is, as shown in Fig. 4, a certain allowable range is given to u and v for the transition value H of the braking traveling speed that would be caused by the pressing force of the brake pedal at that time, and the rotational speed of the wheel is When it deviates from either of these widths, the solenoid valve is opened or closed so that it returns to within both widths. That is, when high brake pressure is required, the high pressure solenoid valve is opened, and when low brake pressure is required, the drain system solenoid valve is opened. As a result, the hydraulic pressure that has been adjusted to be reduced or increased allows the brake to be loosened and prevented from being loosened too much, and the rotation of the wheels is made approximately equal to the braking traveling speed, thereby preventing the wheels from locking.

Such anti-skid control requires subtle changes in adjusting the hydraulic pressure to the wheel cylinders. However, the above-mentioned solenoid valve simply opens and closes the hydraulic circuit by its valve operation, and in addition, its control depends on the mechanical operation of opening and closing. Therefore, it is impossible to arbitrarily select the valve opening degree, and there may be a delay in response. Therefore, there is a problem in that it is not possible to change the braking force to the wheels subtly, quickly, and with good responsiveness via the wheel cylinder.

[Purpose of the invention]

The present invention was made in view of the above-mentioned problems, and its purpose is to eliminate the delay in response caused by mechanical operation, and to be able to adjust hydraulic pressure steplessly and continuously, so as to prevent To provide a braking device for a vehicle capable of subtly and quickly responding to braking force applied to wheels in skid control.

[Structure of the invention]

The characteristics of the vehicle braking device of the present invention are as follows. A brake pedal, a master cylinder that converts the brake pedal depression force into fluid pressure, a brake force control section that receives fluid sent from the master cylinder and generates fluid pressure regulated by a fluid adjustment means, and this brake force. It has a wheel cylinder that transmits braking force to the wheels using fluid pressure generated in the control section, and the fluid pressure adjustment means includes a magnetic fluid that is circulated by a pump and transmits pressure to the brake force control section by viscosity control using a magnetic field. , comprising a magnetic field generating means for variably controlling the viscosity of the magnetic fluid, and a magnetic field controlling means for receiving at least a vehicle speed signal and transmitting a control signal for preventing the wheels from locking to the magnetic field generating means. It is.

〔Example〕

Hereinafter, the present invention will be explained in detail based on examples thereof.

FIG. 2 is a system diagram of a vehicle braking system according to the present invention, and its main mechanical components are a brake pedal 1 that is depressed by the driver, a master cylinder 2 that converts the pedal force of the brake pedal 1 into fluid pressure, and a master cylinder 2 that converts the pedal force of the brake pedal 1 into fluid pressure. a brake force control section 3 that receives fluid sent out from the master cylinder 2 and generates fluid pressure regulated by a fluid adjustment means 10, which will be described later;
It consists of a wheel cylinder 4 that transmits braking force to wheels (not shown) using fluid pressure generated by the brake force control section 3. By the way, the working fluid in this braking device is a magnetic fluid mixed with iron powder, etc., and is filled in the master cylinder 2, the brake force control unit 3, and the wheel cylinder 4, which are in communication with each other. Since this magnetic fluid is supplied from the outside to or discharged from the brake force control section 3, the brake force control section 3 is provided with a pump 5 via a check valve 6, and
A drain passage 8 is provided toward an oil reservoir 9 and includes a safety valve 7 that opens upon receiving an ignition signal. Note that the pump 5 supplies a certain amount of magnetic fluid to the brake force control unit 3 while the brake pedal is not operated.
It is rotated to the extent that it can be filled. The fluid pressure adjustment means 10 that adjusts the oil pressure of the brake force control section 3 described above is as follows:
A magnetic fluid 11 that is circulated by the pump 5 and transmits pressure to the brake force control unit 3 through viscosity control using an applied magnetic field, a magnetic field generating means 12 that variably controls the viscosity of this magnetic fluid, and a wheel locking system that receives at least a vehicle speed signal. The magnetic field control means 13 is provided to send a control signal to the magnetic field generation means 12 to prevent this. That is, the magnetic field generating means 12
Since it changes the drain amount of the magnetic fluid 11 during anti-skid control, it is a solenoid coil or the like provided so as to surround a part of the drain passage 8, and is excited in response to a signal from the magnetic field control means 13. The excitation level can be adjusted, the excitation can be canceled, and the excitation level can be adjusted. Therefore, the magnetic field changes depending on the excitation and its degree, and the viscosity of the magnetic fluid changes at that position, so the pipe friction resistance of the drain passage 8 changes.
The degree of occlusion at that position changes. The magnetic field control means 13 is a microcomputer that calculates whether anti-skid control is necessary during braking and outputs an excitation signal to the magnetic field generation means 12 as necessary. In addition, this also outputs a command to change the discharge amount of the pump 5 according to the depression force on the brake pedal 1 and replenish the magnetic fluid 11 discharged from the drain passage 8 at any time in a braking state where anti-skid control is not required. It looks like this. For this purpose, a pedal angle sensor 14 that detects the pedal force on the brake pedal 1 and inputs the signal to the magnetic field control means 13 is provided to the brake pedal 1, and a pressure sensor 15 that detects the hydraulic pressure of the magnetic fluid is provided to the brake force control section. 3 are attached to each. In addition to these, a vehicle speed sensor 16 is provided that detects a traveling speed signal of the vehicle by detecting the rotation of the wheels, and also detects the actual rotational speed of the wheels in anti-skid control.

This sensor, for example, detects the rotation of an axle based on the rotation of a gear-like pulse gear, and detects the rotation speed using an electromagnetic pickup.

According to this embodiment, anti-skid control can be performed by applying a magnetic field to the magnetic fluid to change its viscosity as described below. First, when the engine is started, the safety valve 7 is opened in response to an ignition signal at that time, and at the same time, the pump 5 is driven. The magnetic fluid 11 pumped up from the oil reservoir 9 is supplied to the brake force control section 3 via the check valve 6, and is filled into the master cylinder 2 and the wheel cylinder 4 via the brake force control section 3. At this time, the excess magnetic fluid 11 is discharged through the drain passage 8, but the discharge amount at that time is kept at a predetermined value by the magnetic field generating means 12 which receives a signal from the magnetic field controlling means 13. When the automobile runs, the vehicle speed sensor 6 detects the vehicle speed from the rotational speed of the wheels, and the detected speed is input to the magnetic field control means 13.

Now, when brake pedal 1 is depressed at a certain angle,
This is detected by the pedal angle sensor 4, and the magnetic field control means 13 calculates and stores a transition value of the braking traveling speed that will provide ideal deceleration from the angle and the vehicle speed. Since the fluid pressure required to achieve that speed is stored in advance, the rotation of the pump 5 is controlled to achieve that pressure. As the oil pressure in the wheel cylinder 4 increases and the two pistons 4a move apart, brake shoes (not shown) come into pressure contact with the inner surface of the brake drum, thereby applying braking to the wheels. In addition, pressure sensor 1
5 applies feedback, and the pressure in the brake force control section 3 is controlled to a desired value.

If the road surface is in poor condition, the rotational speed of the wheels may deviate from the above-mentioned braking speed during braking.

That is, since the supply of the magnetic fluid 11 by the pump 5 is maintained in the same way as when there is no slip, if the braking force is too strong, the wheels are locked and slip occurs. This is because the fluid pressure in the wheel cylinder 4 is high.
Anti-skid control is required. For this purpose, the magnetic field control means 13 calculates the deviation between the braking traveling speed and the actual rotational speed of the wheels, and outputs a signal for weakening the excitation depending on the degree of the deviation. The viscosity of the magnetic fluid 11 in the drain passage 8 is reduced by the weakened magnetic field, facilitating its discharge into the oil reservoir 9. As a result, the body pressure of the brake force controller 3 and the wheel cylinder 4 decreases, the brake force is reduced, and the contact force of the wheels with the road surface is restored. At this time, if the braking force becomes too weak, the desired braking by the brake pedal 1 will not be possible, so the magnetic field control means 13 again sends an excitation signal to the magnetic field generating means 12 in accordance with the deviation so that the vehicle speed returns to the target braking speed. is output to. As a result, the viscosity of the magnetic fluid 11 in the drain passage 8 is increased by the applied magnetic field, and the amount discharged from the drain passage 8 is regulated. Therefore, the fluid pressure is increased and the wheel cylinder 4
The braking force at is increased, and operations are performed sequentially to follow the braking travel speed.

Note that if an oil problem occurs due to damage to the brake system pipes, the brakes may become ineffective, but in this embodiment, the pump is controlled to generate pressure corresponding to the pedal force while detecting the pressure in the brake force control unit 3. Therefore, sudden loss of braking force can be avoided.

In the above example, the magnetic fluid also serves as the brake oil, but in FIG. 3, the magnetic fluid and the brake oil 1 are separated by the piston 17 in the brake force control section 3. In this braking device, the master cylinder 2 and the piston chamber 18 communicate with each other, and the piston chamber 18 expands when the brake pedal 1 is depressed, while the piston chamber 20 contracts when the piston 17 moves in the direction of the arrow 19. Brake oil is supplied to the wheel cylinders 4. Magnetic fluid chambers 21 and 22 having the same cross-sectional area are formed at both ends of the piston 17.

In such an example, when anti-skid control is not required, no signal is issued from the magnetic field control means 13 to the magnetic field generating means 12, and the ferrofluid 11 supplied by the pump 5 flows into the ferrofluid chamber 21.22. acts with the same pressure as As a result, the force of the magnetic fluid 11 on the piston 17 is canceled out, and the piston chamber 20 is compressed by the piston 17, which is thereby displaced when the brake oil 23 from the master cylinder 2 flows into the piston chamber 18. Brake oil 24 is supplied to two wheel cylinders 4 to brake the wheels. When anti-skid control is required by the magnetic field control means 13, an excitation signal is outputted from there to the magnetic field generation means 12. Since the magnetic field generating means 12 is provided only in the drain passage 8A, the viscosity of the magnetic fluid 11a on the side of the magnetic fluid chamber 21 in the drain passage 8A is increased. for that,
Since the force in the chamber 21 is greater than the force in the magnetic fluid chamber 22 on which the magnetic fluid 11b whose pressure does not change acts, a force in the opposite direction to the arrow 19 acts on the piston 17. Therefore, even if the depression force applied to the brake pedal 1 is large, the force that tries to expand the piston chamber 18 is partially offset and weakened, and the pressure increase of the brake fluid supplied from the piston chamber 20 to the wheel cylinder 4 is suppressed, and the pressure of the brake oil is suppressed. Locking is avoided and the contact force with the road surface is restored.

〔Effect of the invention〕

As can be seen from the description of the embodiments above, the present invention provides a magnetic field generating means that changes the viscosity of the magnetic fluid circulated by the pump, and also has a magnetic field generating means that changes the viscosity of the magnetic fluid circulated by the pump. Since the magnetic field control means for sending the control signal to the magnetic field generation means is provided, the braking force exerted by the brake pedal can be reduced and the contact force of the wheels can be restored.

Furthermore, since the anti-skid control is performed without mechanical operation, delicate pressure adjustment is possible and responsiveness can be improved. In addition, since the viscosity of the magnetic fluid can be changed continuously and smoothly, linear control becomes easy and controllability can be improved.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of the present invention, Fig. 2 is an overall system diagram showing an embodiment of the present invention, Fig. 3 is a main part system diagram of a different embodiment, and Fig. 4 is a control in undesired control. It is a principle diagram. 1--brake pedal, 2-master cylinder, 3-.
- Brake force control unit, 4 - Wheel cylinder, 5 - Pump, 10. - Fluid adjustment means, 11. IIa, 1lb--
1-magnetic fluid, 12-magnetic field generation means, 13-magnetic field control means. 4

Claims (1)

[Claims] (1) A brake pedal, a master cylinder that converts the brake pedal depression force into fluid pressure, and a brake force control section that receives fluid sent from the master cylinder and generates fluid pressure regulated by a fluid pressure adjustment means. and a wheel cylinder that transmits braking force to the wheels using fluid pressure generated in the brake force control section, and the fluid pressure adjusting means is circulated by a pump and transmits pressure to the brake force control section through viscosity control using a magnetic field. A magnetic field generating means for variably controlling the viscosity of the magnetic fluid, and a magnetic field controlling means for receiving at least a vehicle speed signal and sending a control signal for preventing the wheels from locking to the magnetic field generating means. A vehicle braking device characterized by: