JPH035340B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wheel lock prevention device, and more particularly to a device that eliminates a sudden drop in wheel speed, or wheel lock, that may occur when braking a vehicle by reducing brake fluid pressure. .

Conventionally, anti-skid devices have been equipped with large pneumatically operated pressure reducing devices, but when the brake fluid pressure needs to drop, the pressure fluid in the brake fluid pressure transmission system is released to the reservoir mechanism, making it necessary to raise the brake fluid pressure again. Sometimes, a switching valve-type anti-lock 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 for its characteristics of being suitable for

As one of the configurations of such a switching valve type wheel lock prevention 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 as a shut-off valve) is disposed, and a passage connected by bypass (hereinafter referred to as a bypass passage) is provided to this main passage,
A normally closed second switching valve (hereinafter referred to as a pressure reducing valve) is arranged between the bypass path and the main path so that it is normally closed, and is opened when it is necessary to lower the brake fluid pressure. The route includes
It has a configuration that includes a reservoir mechanism that receives the pressure of the brake fluid flowing in and stores it while decreasing the fluid pressure by increasing the chamber volume, and a pump mechanism that pumps the fluid stored in the reservoir mechanism to the main path, The opening/closing operations of the shut-off valve (normally open type) and the pressure reducing valve (normally closed type) are performed by an electronic control circuit that detects wheel lock during vehicle braking.

By the way, if we consider the state of control of wheel brake fluid pressure by such a wheel lock prevention device, first of all, in order to prevent the brake force from becoming too excessive, the shut-off valve is initially closed and the brake fluid pressure is prevented from increasing further. If the drop in wheel speed is still not resolved by stopping the increase, there is a pressure reduction process in which the brake force is reduced by opening the pressure reducing valve and releasing the brake fluid pressure to the reservoir mechanism, and the wheel speed also decreases. When the brake fluid pressure is restored by reducing the brake fluid pressure, there is a repressurization process to pump up fluid from the reservoir mechanism and restore the brake fluid pressure. When pumping fluid to the brake system, which is cut off from the brake fluid, the characteristics of the brake fluid pressure re-pressurization process are controlled by the performance of the pump mechanism, making it difficult to select control such as rapid, gradual, or maintaining pressure midway. On the other hand, when the fluid is pumped to the master cylinder side and repressurization is performed by controlling the opening and closing of the shut-off valve, the fluid pumping is used as the return force of the brake pedal. There was a problem with the impact (so-called shock).

In view of these problems, the present invention has been made with the object of making it possible to properly control the characteristics of brake fluid pressure reduction and repressurization, including the state of fluid pressure maintenance, without causing any backlash. It is.

That is, the features of the present invention are to improve the above-mentioned switching valve type wheel lock prevention device, and to provide an intermediate fluid chamber on the master cylinder side of the shut-off valve that becomes sealed when the brake fluid pressure is reduced; An accumulator is provided that is paired with the liquid chamber and holds the pressure liquid pumped up by the pump mechanism, and this pumps up the pressure liquid appropriately into the intermediate liquid chamber, and also releases this holding pressure liquid as necessary. The reason is that it can be returned to the brake equipment side.

The gist of the present invention as a device that specifically realizes these features is a main path for transmitting brake fluid pressure connecting from a master cylinder to a brake device, and a main path for transmitting brake fluid pressure that connects a master cylinder to a brake device. an intermediate liquid chamber is formed between a normally open first valve that divides the main path into an input/output system and closes the circuit by electromagnetic force, and the first valve that is located within the main path input system. a normally open second valve, and a bypass path for liquid return bypassed to the first valve between the main path output system and the intermediate liquid chamber, the bypass path being connected to the main path output system. From the normally closed third valve, which is normally closed and opened by electromagnetic force, the fluid is sequentially passed through a reservoir mechanism including a piston that moves to increase the chamber volume due to the action of inflow pressure, a pump mechanism, and an accumulator. The brake fluid is configured to be supplied to the intermediate fluid chamber, and the second valve is configured to transition from a normally open state to a closed circuit in conjunction with brake fluid pressure reduction due to opening of the third valve. There is a wheel lock prevention device.

In the above, the switching of the second valve from the normally open state to the closed state is basically performed when the hydraulic pressure balance of the input and output systems in the main path becomes (input system) > (output system). For example, a solenoid valve that operates electromagnetically with a slight delay in switching the third valve from electromagnetic close to open, or a hydraulic valve that operates from both the input and output systems. The switching may be performed using a receiving piston or the like, or the amount of movement of a reservoir piston of a reservoir mechanism provided in the bypass path may be used for switching.

In addition, the accumulator in the device preferably does not take in the amount of liquid at the level of the hydraulic pressure that occurs in the main path during normal braking, and when a higher level of hydraulic pressure is generated by the pump mechanism. It is preferable to configure the device so that the liquid is taken inside and stored for the first time.

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

In the figure, 1 is an input port of a valve device connected to a hydraulic pressure transmission pipe (not shown) from the master cylinder M/C, and 2 is a hydraulic pressure transmission pipe (not shown) to a wheel brake device W/C. These input and output ports 1 and 2, including the flow path 3 in the valve device that connects them, form the main path for transmitting brake fluid pressure. However, in the following explanation, the main path will be divided into an input/output system and an intermediate liquid chamber within the input system, so for convenience, input port 1 will be referred to as input system A, flow path 3 will be referred to as intermediate liquid chamber B, and output Let port 2 be shown as output system C.

4 is a normally open type first valve interposed in the main path, and is composed of a valve seat 5, a valve body 6a formed on a part of a movable iron core 6, a hold spring 7, and a solenoid 8. Normally, the spring force of the hold spring 7 maintains the flow path in a normally open communication state, and the excitation of the solenoid 8 causes the flow path to transition to a closed state. Note that the timing of excitation of the solenoid 8 will be described later.

The first valve 4 divides the main path into input systems A and B and output system C.

Reference numeral 9 denotes a bypass passage connected to the main passage in the valve device, and a normally closed third valve 1.
0 to the main path output system C, and is also connected to the main path intermediate liquid chamber B via a check valve 11 that forms a pair with an accumulator described later. Here, in the third valve 10, the valve body 13a is seated against the open valve seat 12 on the main path side by the spring force of the hold spring 14, and the movable iron core 13 integrated with the valve body 13a is connected to the solenoid 15. When the valve body 13a is electromagnetically attracted by excitation, the valve body 13a is attracted to the valve seat 1.
It is configured to be spaced apart from the two.

In the bypass path 9, a reservoir mechanism 16 and then a pump mechanism are sequentially provided following the second valve 10, and the pressurized liquid pumped up by this pump mechanism is taken into and stored in the next stage accumulator. It is becoming more and more common. The pressure liquid stored in this accumulator is then fed to the intermediate liquid chamber B via the check valve 11 described above.

In the reservoir mechanism 16, the reservoir piston 18 that is slidably fitted to the cylinder 17 is normally biased to a rest position by the spring force of the reservoir spring 19, and when pressurized fluid flows into the bypass path 9, the reservoir piston 18 is biased by the spring force of the reservoir spring 19. By moving against the spring force of 19, the pressure value of the pressure liquid is lowered. Further, the reservoir mechanism of this example also serves as a drive mechanism for switching the second valve from opening to closing, which will be described later, and this point will be described later.

The pump mechanism 20 includes, for example, a pair of check valves 21 and 22, a reciprocating plunger 23, and an eccentric cam 24 that is assembled to a motor or the like and rotates when necessary to cause the plunger 23 to reciprocate. .

25 is an accumulator disposed on the discharge side of the pump mechanism 20;
The pressure fluid pumped up from 0 is stored and held inside,
It functions to feed this pressurized liquid to the intermediate liquid chamber B via the check valve 11 facing the intermediate liquid chamber B described above.

Next, the normally open type second valve 26 that partitions the intermediate liquid chamber B together with the first valve 4 in the main path input system will be described. This second valve 26 in this example
consists of a ball 29 that is pushed against the valve seat 27 by a hold spring 28, and a locking rod 30 that engages the ball 29 so as to normally separate it from the valve seat 27. When the ball bias is released, the ball 2
9 is seated on the valve seat 27, and the input system A is connected to the intermediate liquid chamber B.
The flow path is closed so as to allow liquid flow in the opposite direction, but restrict liquid flow in the opposite direction. Note that the locking rod 30 in this example
is maintained at the initial rest position (the illustrated position where the ball 29 is spaced apart from the valve seat 27) by the pressing spring force of the reservoir spring 19 via the reservoir piston 18 of the reservoir mechanism 16. Note that 31 is a piston cup for liquid-tightly sealing the sliding portion of the locking rod 30.

The second valve 26 having such a configuration is switched from open to closed by movement of the reservoir piston 18.

The above is an outline of the configuration of the wheel lock prevention device for realizing the present invention. In this example, a relief valve 32 is provided to ensure liquid recirculation from the main path output system C to the input system A, and the anti-lock lock prevention device is provided with a relief valve 32 to ensure liquid recirculation from the main path output system C to the input system A. This allows liquid to flow back when the pedal is released.

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 during normal wheel braking is as follows: input port 1 → normally open second valve 26 and first valve 4 → The signal is transmitted to the brake device via the output port 2 and generates the required braking force. At this time, the third valve 10 is normally closed.

During wheel lock prevention control If this stage is divided into two stages: closing of the first valve 4 and opening of the third valve 10, first the closing of the first valve 4 is performed by energizing the solenoid 8; As a result, communication between the input port 1 and the output port 2 is cut off, so that the brake fluid pressure within the brake device no longer increases regardless of whether the brake pedal is depressed. This operation is caused by the excitation of the solenoid 8, which causes the valve body 6a to
The action of abutting and seating against the valve seat 5 can be electromagnetically performed extremely quickly.

The solenoid 8 for closing the first valve 4 may be energized by detecting the start of a sudden drop in wheel speed during wheel braking by an electric control circuit (not shown), and by energizing the solenoid 8 for closing the first valve 4. It is preferable to start driving the mechanism 20 from this point.

Next, when the solenoid 15 is energized, the movable iron core 13 moves to the left in the figure against the hold spring 14, and the third valve 10 opens.

Therefore, the brake pressure fluid flows into the reservoir mechanism, and the reservoir piston 18 begins to move against the spring thrust of the reservoir spring 19, causing a sudden drop in brake fluid pressure.

Opening of this third valve 10, reservoir piston 18
With this movement, the second valve 26 is switched from open to closed via the locking rod 30, and the main path input system A is cut off from the intermediate liquid chamber B.

Then, by opening the third valve, the main path output system C (cut off from the input system by closing the first valve 4)
The pressure liquid flows from the reservoir mechanism into the pump mechanism 20, and is pumped up to the accumulator 25 by the operation of the pump mechanism 20.

The pressure liquid pumped up into the accumulator 25 is in a state where it can be fed to the intermediate liquid chamber B via the check valve 11, but this intermediate liquid chamber B is separated from other liquids by the first valve 4 and the second valve 26. Since it is in a sealed state, the pressure fluid is stored and held within the accumulator 25.

When the brake fluid pressure rises again during wheel lock prevention control When the wheel lock is released due to a drop in the brake fluid pressure, the excitation of the solenoid 15 is stopped and the third valve 10 returns to the normally closed state.

In this state, the first valve 4, the second valve 26, and the third valve 10 are all closed, so the main path input system A (master cylinder side), the intermediate liquid chamber B, the main path output System C (brake device side) is not in communication with each other, and the brake fluid pressure in main path output system C is reduced by the series of operations described above, and a predetermined amount of pressure fluid is stored in the accumulator 25. It is now in a state of flux.

If the first valve 4 is conveniently opened here, the brake fluid pressure on the main path output system C, that is, on the brake device side, can be appropriately repressurized.

Note that the repressurization characteristics can be selected by variously selecting the open state of the first valve 4. As the first valve opens during this repressurization, the intermediate liquid chamber B
Pressure fluid is supplied from the accumulator 25.

Of course, if the wheels lock again during this process, the above operation will be repeated.

In the above series of operations, even with the brake fluid pressure, the pumped fluid is stored in the accumulator regardless of the main path input system, so there is no effect of so-called kickback, and
By electromagnetically controlling the hydraulic pressure, repressurization, and pressure maintenance of the first and third valves, it is possible to quickly and accurately respond to changes in the actual wheel speed.

Next, the operation control of the first valve 4 and the third valve 10 in the wheel lock prevention device with the above configuration will be explained. As already mentioned, the operation of the first valve 4 is as follows.
It is preferable to prevent the hydraulic pressure in the brake system from increasing any further due to this occurring in the initial stage when the wheel speed drops beyond the appropriate level during vehicle braking, so for example, the detected wheel speed signal The first valve 4 is operated electromagnetically at the time t ₀ when V _W exhibits a deceleration higher than a certain set deceleration gradient V _T1 , while the third valve 10 is operated according to the above-mentioned method. This often occurs when it is insufficient to stop the increase in brake fluid pressure due to the operation of valve 1. For example, for example, when the wheel speed is V _{W -}
Set a pseudo speed V _T2 which is a signal of ΔV = V _T2 and whose rate of descent is regulated below a certain value,
It is preferable to compare V _T2 and V _W and to perform electromagnetic operation of the third valve 10 at a time point t ₁ when V _T2 >V _W.

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. In addition, the first
The operation of the valve 4 and the third valve 10 is stopped under the condition that V _T1 > V _W for the former, and for the latter, for example,
The condition can be that _VW has recovered to a certain value from a low peak.

Note that the circuit configuration for controlling the operation of the first valve and the third valve as described above can be formed using known electrical technology. Note that the operation control of the device of the present invention is not intended to be limited to that described above.

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 drawings]

The drawings are diagrams showing the basic configuration of an embodiment of the present invention. 1...Input port, 2...Output port, 3...
Main path, 4...First valve, 5...Valve seat, 6...Movable iron core, 6a...Valve body, 7...Hold spring, 8...Solenoid, 9...Bypass path, 1
0... Third valve, 11... Check valve, 12... Valve seat, 13... Movable iron core, 13a... Valve body, 14...
...Hold spring, 15...Solenoid, 1
6... Reservoir mechanism, 17... Cylinder, 18...
... Reservoir piston, 19 ... Reservoir spring, 20 ... Pump mechanism, 21, 22 ... Check valve, 23 ... Plunger, 24 ... Eccentric cam,
25... Accumulator, 26... Second valve, 2
7...Valve seat, 28...Hold spring, 29
... Ball, 30 ... Locking rod, 31 ... Piston cup, 32 ... Relief valve.

Claims (1)

[Claims] 1 A main path for transmitting brake fluid pressure that connects the master cylinder to the brake device, and a normal path that is interposed in this main path and divides the main path into an input/output system and is closed by electromagnetic force. an open type first valve;
a normally open second valve located within the main path input system and forming an intermediate liquid chamber between the main path input system and the first valve; and a normally open second valve that is bypassed by the first valve between the main path output system and the intermediate liquid chamber. The bypass path is normally closed to the main path output system and is opened by electromagnetic force to reduce the indoor volume by the action of inflow pressure liquid. The brake fluid is configured to be supplied to the intermediate fluid chamber through a reservoir mechanism including a piston that moves to increase the amount of brake fluid, a pump mechanism, and an accumulator, and the second
A wheel lock prevention device characterized in that the valve is configured to shift from a normally open state to a closed state in conjunction with brake fluid pressure reduction due to opening of the third valve.