JPH0342225B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a brake fluid pressure holding device for a vehicle, and more particularly to a method for holding brake fluid pressure and gently opening and closing a path of a switching valve when releasing brake fluid pressure. It is something.

In general vehicle driving operations, when a vehicle is brought to a stop by braking, it is necessary to keep pressing the brake pedal to secure braking force, release the brake pedal and leave it alone, or even stop the vehicle on a slope. The operation of operating the parking brake device to maintain a reliable stopped state, as is often done in other cars, is done selectively depending on the situation at the time, the driver's habits, etc. It's normal.
However, since it is not desirable for a stopped vehicle to suddenly move, it is desirable to operate the parking brake device described above or to continue to depress the brake pedal.

However, such an operation is complicated, and since the parking brake is often not used except on slopes, there is a risk that a stopped vehicle may end up in a state where no braking is applied and cause the vehicle to move unexpectedly.

Therefore, the applicant has proposed that after the vehicle is stopped by performing a braking operation on a vehicle equipped with a hydraulic braking mechanism, that is, by performing a brake operation, the vehicle is moved forward (or reversed).
The purpose of this brake is to mechanically and automatically maintain the wheel cylinder fluid pressure (brake fluid pressure) in the brake device until an operation is performed, such as engaging the clutch and starting the vehicle. An electromagnetically actuated switching valve (hereinafter referred to as an auto-stop valve) is installed in the hydraulic pressure path connecting an input device such as a master cylinder to a wheel cylinder. We have developed a system that maintains the brake fluid pressure in the wheel cylinder during vehicle starting operations.

This basically has the following configuration. In other words, in a vehicle's brake fluid pressure transmission system, the input fluid chamber on the master cylinder side and the output fluid chamber on the brake equipment side, and a normally open switching valve that can open and close communication between these, and this switching valve are used by amateurs. and an electromagnetic actuation mechanism that shifts the switching valve to a closed state by movement of the switching valve, and maintains the switching valve in the closed state by the operation of the electromagnetic actuation mechanism when the vehicle is stopped.

By the way, in the brake fluid pressure transmission system in which an auto-stop valve for opening and closing such a path is interposed, it has been recognized that the following points should be improved in actual use. For example, if we consider the situation when the hydraulic pressure contained in the brake system is returned to an input device such as a master cylinder (hereinafter referred to as master cylinder) when the vehicle next starts, this means that the auto stop valve electromagnetically changes the path. As a result of releasing the closed state, high hydraulic pressure within the brake system is instantaneously transmitted to the mass cylinder, which often causes the brake pedal to return to its original position with an impact, causing an abnormal noise. It is thought that this may cause noise (sound) and give an unexpected shock to the driver. Further, the above-mentioned abnormal noise (knocking noise) is often generated when the switching valve is driven to close the path.

In short, the occurrence of such abnormal noise is caused by the movable body (valve disc, etc.) inside the auto-stop valve colliding with the inner wall of the valve body, etc.
This is an undesirable sound that is frequently repeated every time the vehicle is stopped, and is also undesirable in terms of wear and tear on the parts over time.

These things, that is, maintaining brake fluid pressure when the vehicle is stopped and releasing it, basically do not need to be done instantly, and it is rather desired to eliminate the above-mentioned difficulties in doing them instantly. In view of this, the present invention has been made.

The gist of the present invention to achieve this object is to provide a normally open electromagnetic switching valve (auto stop valve) in a path for transmitting brake fluid pressure between a vehicle's fluid pressure source and a brake device. In this method, the switching valve (auto stop valve) is actuated to confine hydraulic pressure within the brake device when the vehicle is stopped. A brake fluid pressure holding control method is characterized in that the brake fluid pressure is gradually increased, and the closing of the switching valve is performed by gradually decreasing the current flowing through the valve drive solenoid.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an example of an auto-stop valve in a brake fluid pressure control device to which the method of the present invention is applied. In the figure, 1 is a valve body, and an input port 2 is connected to a master cylinder (not shown). and an output port 3 connected to a brake device (not shown), and cylinders 4a and 4b, in which communication holes from these ports are partially open, are opened to the outside via a threaded portion 5. It is formed like this. And this cylinder 4
In this example, a and 4b are formed to have different diameters such that the diameter becomes smaller in the order of the threaded portion 5, the cylinder 4b following this, and the cylinder 4a following this.

Further, a communication hole from the input port 2 opens to the circumferential surface of the cylinder 4a, and a communication hole from the output port 3 opens to the circumferential surface of the cylinder 4b.

A plug 6 is fitted into the cylinders 4a and 4b through the threaded portion 5, and is fixed by a plug stopper 7 screwed into the threaded portion 5. A part of the outer circumference of the plug 6 is liquid-tightly attached to the circumferential surface of the cylinder 4a, thereby dividing the inside of the cylinder into two chambers between the communication holes from the input/output ports 2 and 3. A piston cup 8 is attached. With this piston cup 8, the inside of the cylinders 4a and 4b is divided into an input liquid chamber a communicating with the input port 2 and an output liquid chamber b communicating with the output port 3.
It will be classified. Reference numeral 9 designates an O-ring that is attached to the outer periphery of the plug 6 and snaps onto the cylinder 4b to prevent liquid from leaking from the output liquid chamber b to the threaded portion 5 side.

The plug 6 has a cylindrical shape with one end open at the end of the plug inserted into the cylinder, and a seat valve 10 having a conical ball seat surface 10a is fixed to the opening. A rod valve 11 is inserted into the cylindrical portion and extends through the axial center passage of the seat valve 10 and projects onto the ball seat surface 10a.
is built in, and biased spring force is applied by a set spring 12 in a direction protruding from the ball seat surface 10a. Reference numeral 6a denotes a radial passage that communicates between the inner cylinder of the plug 6 and a chamber communicating with the output port 3, and therefore the inner cylinder of the plug also forms a part of the output liquid chamber b. Also, 13 is the ball seat surface 10
The ball is placed facing the ball seat surface 10a, and is normally separated from the ball seat surface 10a by the rod valve 11, and receives a pressing force from the push rod 15 by the operation of an electromagnetic actuating mechanism, which will be described later. The ball seat surface 10a is configured to abut against the ball seat surface 10a.

Therefore, the output fluid chambers a and b are normally in communication because the ball 13 is spaced apart from the ball seat surface 10a, and therefore the pressure fluid from the master cylinder is directly transmitted to the brake device. When the electromagnetic actuation mechanism described later is activated before the brake pedal is released when the vehicle is stopped, the ball 13 comes into contact with the ball seat surface 10a while the brake fluid pressure is maintained in the brake device. However, communication between the input and output liquid chambers a and b is closed.
For this reason, even if the brake pedal is released after this, as long as the closed state of the valve part is maintained electromagnetically, the brake fluid pressure in the output fluid chamber b, that is, in the brake device, is maintained, and the braking force is maintained.

Next, to explain the electromagnetic actuating mechanism, in the housing 15 fastened and fixed to the valve body 1, there is a fixed iron core 16 into which the push rod 14 is slidably fitted. , a movable iron cylinder 17 which is arranged facing each other while maintaining a predetermined clearance, and a solenoid 18 which is arranged so as to surround these iron cores.

In the auto-stop valve of this example having the above-described configuration, when the traveling vehicle is stopped by a braking operation, the solenoid 18 is energized and attracts the movable iron core 17. The ball 13 is seated on the ball seat surface 10a, cutting off communication between the input and output fluid chambers a and b, and when the next vehicle start operation cancels the excitation of the solenoid, the wheel of the brake device It operates to release the hydraulic pressure held in the cylinder to the master cylinder side.

Figures 2A and 2B show an example of an electric circuit in which the method of the present invention is realized for drive control of the auto-stop valve described above. In Figure 2A, 20 is a vehicle speed sensor, for example, a wheel rotation speed detection of,
Alternatively, by detecting this and the vehicle deceleration and acceleration, the vehicle stopped state is detected. 21 is an accelerator switch that detects depression of the accelerator pedal, and the output signal of the vehicle speed sensor 20 and the output inversion signal of the accelerator switch 21 are connected to an AND circuit 22.
The output of the AND circuit 22 causes the solenoid 18 of the auto-stop valve to be activated via the auto-stop valve drive control circuit 23.
It is designed to energize and de-energize.

The drive circuit 23 has a normally open switch SW that is turned on by the output of the AND circuit 22, and as the switch SW turns on and off, the capacitor changes.
Charging and discharging C ₁ , transistors Q ₁ , Q ₂ , Q ₃ , Q ₄
The solenoid 18 is turned on and off as described below, and the solenoid 18 is energized and de-energized. That is, when the brake fluid pressure is maintained, by closing SW, _C1 is charged through _R6 , _V1 gradually rises, the base current of _Q3 increases, and the collector of _Q3 The current also increases. Accordingly, the base current of Q ₄ also gradually increases, and therefore the collector current of Q ₄ gradually increases, and the excitation force of the solenoid 18 gradually increases.
When _C1 is fully charged and _Q3 's base current flows sufficiently, _Q4 is also completely turned on and solenoid 18 is completely turned on. Note that when SW is closed, _Q1 is on and _Q2 is off.

On the other hand, when brake fluid pressure retention is released, SW changes from closed to open, Q ₁ turns off, Q ₂ turns on, and C ₁ turns on.
It discharges through _R5 and the voltage of _V1 gradually decreases. As a result, the base current of Q ₃ gradually stops flowing, and
The base current of Q ₄ also gradually decreases, thus Q ₄
The collector current of solenoid 18 gradually decreases.
The excitation force gradually decreases. When Q ₃ is completely turned off, Q ₄ is also completely turned off, and solenoid 18 is completely turned off.

In this way, the excitation force of the solenoid 18 of the auto-stop valve gradually increases and decreases, so communication switching between the input and output hydraulic pressures of the auto-stop valve is performed by the ball 13 and the ball seat surface 10a. This is done in accordance with the gentle separation and mating action of the parts, eliminating the abnormal noise (clicking sound) caused by the instantaneous collision of parts, and also eliminates the sudden return of pressure fluid to the input device side. This has the effect of eliminating the risk of damage occurring.

It goes without saying that the speed at which the brake hydraulic pressure is maintained and when it is released can be appropriately changed depending on the circuit design to select a preferable state.

As described above, according to the brake fluid pressure holding control method of the present invention, a suitable control state can be achieved by electromagnetic control of a hydraulic pressure holding valve (auto stop valve) that operates electromagnetically, and in particular,
This not only prevents pressure fluid from suddenly returning to input devices such as the master cylinder when releasing fluid pressure, causing damage to these devices or causing discomfort to the driver, but also prevents the valve from being damaged. Since the movement of the body does not impact against the fixed member, so-called abnormal noises are prevented from occurring, and there is also the effect that the driver etc. will not be given unnecessary suspicions such as equipment failure.

Furthermore, since the mechanical configuration does not require any special changes compared to conventional devices of this type, it is suitable for downsizing the device, and can be applied as is to various types of brake fluid pressure holding devices. Its usefulness is extremely great.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing an example of a hydraulic pressure holding valve to which the method of the present invention is applied, Fig. 2 (a) is a block diagram showing an outline of an electric circuit for operating this liquid pressure holding valve, and Fig. 2 (b) is the same. FIG. 3 is a diagram showing an example of an auto-stop valve drive control circuit in the circuit. 1: Valve body, 2: Input port, 3: Output port, 4a, 4b: Cylinder, 4': Cylinder,
5: Threaded part, 6, 6': Plug, 7: Plug stopper, 8: Piston cup, 9: O-ring, 1
0: seat valve, 10a: ball seat surface, 1
1: Rod valve, 12: Set spring, 1
3: Ball, 14: Push rod, 15: Housing, 16: Fixed iron core, 17: Movable iron core, 1
8: Solenoid, 20: Vehicle speed sensor, 21: Accelerator pedal switch, 22: AND circuit, 23:
Auto stop valve drive control circuit.

Claims (1)

[Claims] 1. A normally open electromagnetic switching valve is interposed in the path that transmits brake fluid pressure between the vehicle's hydraulic pressure source and the brake equipment, and when the vehicle is stopped, the electromagnetic switching valve is driven to transfer fluid pressure into the brake equipment. This method is designed to contain the electromagnetic switching valve, and the generation of abnormal noise when the valve body abuts against the valve seat can be minimized by energizing the valve drive solenoid of the switching valve that closes the electromagnetic switching valve. A brake fluid pressure holding control method characterized in that the brake fluid pressure is gradually increased as shown in FIG.