JPH0339856B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in vehicle anti-lock devices used in vehicles such as motorcycles and four-wheeled vehicles, and more specifically, to a brake fluid pressure transmission system, including a reservoir mechanism for releasing fluid pressure and this reservoir mechanism. The present invention relates to a device in which a pump mechanism for circulating brake fluid from the brake fluid pressure transmission system to the brake fluid pressure transmission system is bypass-connected.

Conventionally, when the brake fluid pressure needs to be lowered, the pressure fluid in the brake fluid pressure transmission system is released to the reservoir mechanism, and the brake fluid pressure needs to be raised again, compared to the conventional antenna lock device that has a large pneumatically operated pressure reducing device. At times, a switching valve type vehicle antilock device (wheel lock prevention device) has been proposed in which the fluid stored in the reservoir mechanism is returned to the brake fluid pressure transmission system using a pump mechanism. It is known to have the characteristic of being suitable for miniaturization.

As one of the configurations of such a switching valve type vehicle antilock device, the following configuration can be considered.

In other words, the brake fluid pressure transmission path (hereinafter referred to as the main path) that connects the master cylinder (hydraulic pressure generation source) and the brake equipment is a normally open type that is normally open and closed when the brake fluid pressure needs to drop. A first switching valve (hereinafter referred to simply as the first valve) is arranged, and a passage connected by bypass (hereinafter referred to as the bypass passage) is provided to the main passage, and a passage is provided between the bypass passage and the main passage. A normally closed second switching valve (hereinafter simply referred to as the second valve) that is closed when the brake fluid pressure is required to decrease.
In addition, this bypass path includes a reservoir mechanism that receives the pressure of the incoming brake fluid and stores it while decreasing the fluid pressure by increasing the chamber volume, and a reservoir mechanism that stores the fluid while reducing the fluid pressure. It has a configuration with a pump mechanism for pumping water,
The opening/closing operation of the first valve (normally open type) and the second valve (normally closed type) is performed by an electronic control circuit that detects wheel lock during vehicle braking.

Considering the control state of the wheel brake fluid pressure to prevent such wheel locking, when the wheel brake force becomes excessive during vehicle braking due to factors such as low road surface μ, the wheel speed (rotational speed ) suddenly drops and this causes a wheel lock phenomenon, creating the risk of losing the steering ability of the vehicle.In this case, it is recommended to reduce the brake fluid pressure to an appropriate value. This is the control purpose of the wheel lock prevention device, and on the other hand, if the brake fluid pressure is lowered too much, the vehicle braking distance will become too long even though the wheels will not lock up. It would be a good idea to be able to descend while maintaining the rate. The wheel lock prevention device operates as described above because the driver is depressing the brake pedal and the vehicle is braking, and the above-mentioned rapid drop in wheel speed occurs within an extremely short period of time. Therefore, it is also necessary to consider conditions such as the device being able to operate with good responsiveness.

By the way, if we consider the pumping of the fluid by the pump mechanism and the repressurization control of the brake fluid pressure, for example, if the fluid is pumped to the master cylinder side rather than the first valve, the repressurization of the brake fluid pressure is There are two possible methods: doing this by opening and closing the first valve, or pumping fluid into the brake system and repressurizing it, but the former causes fluctuations in the brake pedal. This may give the driver a sense of discomfort, and the latter generally requires that a pump drive means such as a motor be continuously driven at the same time as the start of pressure reduction in order to improve the responsiveness of hydraulic pressure repressurization. There is a problem in that it is difficult to maintain brake fluid pressure during pressurization.

From the above, in the present invention, in the initial stage when the wheel speed decreases more than appropriate, the brake fluid in the brake system is reduced by the shaft of the brake fluid pressure transmission path, regardless of whether the brake pedal is depressed. Then, if the wheel speed continues to drop abnormally even after stopping the increase in brake fluid pressure, the fluid pressure in the brake system is diverted to the reservoir. By releasing the brake fluid, the brake fluid can be rapidly lowered, and when the wheel speed has recovered, the brake fluid that has been released into the reservoir can be pumped up to the brake equipment side to gradually increase the brake fluid pressure in order to prevent an extension of the braking distance. The present invention provides an anti-lock device for a vehicle that is capable of maintaining hydraulic pressure during descent and repressurization.

The feature of the vehicle anti-lock device according to the present invention that achieves the above object is that the master cylinder 2
A main path for transmitting brake fluid pressure is connected between the main path and the brake device, and a normally open first valve that is electromagnetically closed is interposed in this main path, and the first valve and the brake device are connected to each other. a bypass path that has a normally closed second valve that is electromagnetically opened and a liquid pump mechanism and is connected to the main path between the main path; and a bypass between the second valve and the pump mechanism. The reservoir mechanism is connected via a normally closed third valve that is electromagnetically opened to the path.

Embodiments of the present invention will be described below based on the principle configuration diagram shown in the drawings.

In the figure, 1 is a brake pedal, 2 is a master cylinder that generates hydraulic pressure according to the pedal force, and 3 is a brake pedal.
6 is a hydraulic pressure transmission pipe that connects the master cylinder 2 to the input port 4 of the valve device, and 6 is a hydraulic pressure transmission pipe that connects the output port 5 of the valve device to the brake device 7, connecting the input and output ports 4 and 5. These hydraulic pressure transmission pipes 3 and 6, including the flow path 8, constitute a main path. In the following explanation, these will be referred to as main path 3,
6 and 8.

Reference numeral 9 denotes a normally open first valve disposed in the main path 8, and is composed of a valve seat 10, a valve body 11a formed in a part of a movable iron core 11, a hold spring 12, and a solenoid 13. Normally, the spring force of the hold spring 12 keeps the flow path 8 in a normally open communication state, and the excitation of the solenoid 13 causes the flow path 8 to be brought into a closed state. Note that the excitation timing of each solenoid including this solenoid will be described later.

Reference numeral 14 denotes a bypass passage connected to the main passage 8 in the valve device, and a normally closed second passage.
The valve 15 and the pump mechanism 21 for pumping up pressurized liquid are connected as connection parts. Here, in the second valve 15, a valve body 18a is seated against an open valve seat 16 on the side of the main path 8 by the spring force of a hold spring 19, and a movable iron core 18 is integrated with the valve body 18a.
The valve body 18a is configured to be separated from the valve seat 16 when the solenoid 20 is electromagnetically attracted by the excitation of the solenoid 20.

The pump mechanism 21 is assembled to, for example, a pair of check valves 22 and 23, a reciprocating plunger 24, a motor, etc., and rotates.
It is composed of an eccentric cam 25 that reciprocates the cam 4.

Reference numeral 26 denotes a branch path branching from the middle of the bypass path 14 to the reservoir mechanism, and a normally closed third valve 27 is provided at the connecting portion. This third valve 27 includes a valve seat 28, a valve body 29a formed in a part of the movable iron core 29, a hold spring 30,
and a solenoid 31. Normally, the spring force of the hold spring 30 maintains the communication of the branch path 26 with the bypass path 14 in a normally closed state, and the solenoid 31 is energized to shift to the open state. .

32 is a reservoir mechanism connected to the branch path 26, and the reservoir piston 34, which is slidably fitted to the cylinder 33, is normally biased to a rest position by the spring force of the reservoir spring 35, and when pressurized fluid is introduced from the bypass path 14, The reservoir piston 34 moves against the spring force of the reservoir spring 35 to lower the pressure value of the pressurized liquid.

Note that a relief valve 36 (or a one-way seal may be provided) is provided between the input port 4 and the output port 5 of the main path to allow hydraulic pressure return only to the input port 4 side.

Next, the operation of the apparatus having the above configuration will be explained.

As is clear from the above, the brake fluid pressure generated in the master cylinder when the vehicle is braked normally flows in the following order: input port 4 → normally open first valve 9 → output port 5. It is transmitted to the brake system via the , and generates the required braking force. At this time,
The second valve 15 and the third valve 27 are normally closed.

During wheel lock prevention control, if this stage is divided into two stages: closing of the first valve 9 and opening of the second valve 15 and third valve 27,
First, the first valve 9 is closed by energizing the solenoid 13, and communication between the input port 4 and the output port 5 is thereby cut off. Regardless of this, the brake fluid pressure within the brake device 7 will no longer increase. And this operation is performed by solenoid 1
The operation of causing the valve body 11a to abut and sit on the valve seat 10 by the excitation of step 3 can be electromagnetically performed extremely quickly.

Next, when the solenoids 20 and 31 are energized, the movable iron core 18 of the second valve moves to the left in the figure against the hold spring 19, and the second valve 15 opens. At the same time, the movable iron core 29 of the third valve moves downward in the figure against the hold spring 30, and the third valve 27 opens.

Therefore, the pressure fluid on the brake device side flows into the reservoir mechanism 32, and the reservoir piston 34 begins to move against the spring thrust of the reservoir spring 35, causing a sudden drop in brake fluid pressure.

At this stage, if the third valve 27 is returned to the closed state while the second valve 15 is kept open,
Since the brake fluid pressure does not drop any further, the brake fluid pressure is maintained at that pressure value. By simply switching the third valve 27 between opening and closing, the brake fluid pressure can be lowered in stages.

When the brake fluid pressure rises again in the wheel lock prevention control, when the wheel lock is released due to a drop in the brake fluid pressure, the excitation of the solenoid 20 is stopped and the second valve 1
5 returns to the normally closed state.

At this time, if the third valve 27 is open, the fluid stored in the reservoir mechanism is gradually pumped up to the main path 8 (brake device side) by the pump mechanism 21, and the brake fluid pressure rises again, and this is sufficient. Once recovered, the first valve 9 is opened to restore communication of the main path to the normal state, and the operation of the wheel lock prevention control is completed.

However, this kind of liquid pumping is impossible due to the third valve 27.
By closing the circuit, it is possible to interrupt, or in other words, stop the re-increase of the brake fluid pressure.
Closing the valve 27 provides control that is the opposite of stopping the drop in brake fluid pressure and maintaining that pressure value. That is, by switching the third valve 27 between opening and closing, the brake fluid pressure can be raised again in stages.

Of course, if the wheels lock again during this process, it goes without saying that the operation of lowering the brake fluid pressure will be repeated.

Next, an example of the operation control of the first valve 9, the second valve 15, and the third valve 27 in the device with the above configuration will be explained.As already mentioned, the closing operation of the first valve 9 is performed during vehicle braking. It is better to prevent the hydraulic pressure in the brake system from increasing any further due to the initial stage when the wheel speed drops beyond the appropriate level. The electromagnetic operation of the first valve 9 may be performed immediately at the time t ₀ when the wheel speed signal V _W detected by a sensor or the like indicates a deceleration higher than the predetermined set deceleration gradient V _T1 .

On the other hand, the operation for lowering the brake fluid pressure by opening the second valve 15 and the third valve 27 is made to occur when it is insufficient to stop the increase in brake fluid pressure due to the operation of the first valve 9 described above. For example, for wheel speed V _W , V _W −ΔV=V _T2
A pseudo speed V _T2 is set and the rate of descent is regulated below a certain value, and this V _T2 and
The second valve 15 can be electromagnetically operated at time t ₁ when V _T2 >V _W by comparing V _W .

When the wheel lock is released due to a drop in brake fluid pressure, the brake fluid pressure may be raised again by simply closing the second valve 15, but generally the wheel speed recovers slowly and quickly. In the above case, for example, from time t ₂ when the wheel speed signal V _W indicates the low peak V _L to time t ₄ until the brake fluid pressure recovers to a constant value ΔV', By returning only the third valve 27 to the closed path, the brake fluid pressure can be maintained at a sufficiently low fluid pressure value.

In addition, as a condition for the brake fluid pressure to rise again, for example, as a condition for stopping the operation of the second valve 15, V _W > V _L +
ΔV′, and as a condition for stopping the operation of the first valve 9, V _T1 >
_VW can be used.

By organizing the above combination relationships in this example, the relationship between the open and closed states of the second and third valves during antilock control, that is, after the first valve 9 is closed, and the drop, hold, and re-rise of the brake fluid pressure is as follows: The result is as follows.

A 2nd valve, 3rd valve...open → brake fluid pressure drop 2nd valve...open or close, 3rd valve...close → brake fluid pressure maintained 2nd valve...closed, 3rd valve...open → brake fluid pressure Re-rising In this way, the brake fluid pressure can be maintained and further lowered selectively depending on the degree of decrease in the wheel speed _VW , and desirable wheel brake force control can be achieved.

Note that the circuit configuration for controlling the operation of the first valve and the second valve as described above can be formed using known electrical technology, and is not limited to controlling the operation of the device of the present invention. This has the advantage that control patterns compatible with various anti-lock control systems can be adopted.

As described above, the wheel lock prevention device according to the present invention can obtain the various excellent effects described above with a relatively simple structure, and is highly useful.

[Brief explanation of the drawing]

The drawing is a schematic diagram of the basic structure of an anti-lock device showing an embodiment of the present invention. 1: Brake pedal, 2: Master cylinder,
3, 6: Hydraulic pressure transmission pipe (main path), 4: Input port,
5: Output port, 7: Brake device, 8: Flow path (main path), 9: First valve, 10: Valve seat, 11: Movable iron core, 12: Hold spring, 11a: Valve body, 13:, 14 :Bypass route, 15:Second
Valve, 16: Valve seat, 1: Movable iron core, 18a: Valve body,
19: Hold spring, 20: Solenoid,
21: Pump mechanism, 22, 23: Check valve, 2
4: plunger, 25: eccentric cam, 26: branch path, 27: third valve, 28: valve seat, 29: movable iron core, 29a: valve body, 30: hold spring,
31: Solenoid, 32: Reservoir mechanism, 33:
Cylinder, 34: Reservoir piston, 35: Reservoir spring, 36: Relief valve.

Claims (1)

[Claims] 1 A main path for transmitting brake fluid pressure connected between the master cylinder and the brake device, and a normally open first valve that is electromagnetically closed is interposed in this main path, and the first valve A bypass path that has a normally-closed second valve that is electromagnetically opened and a liquid pump mechanism and is connected to the main path between the brake device and the brake device; and a reservoir mechanism connected via a normally closed third valve that is electromagnetically opened to a bypass path between the two.