JPS6055340B2 - Anti-skid control actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an actuator for anti-skid control that has stable characteristics under a wide range of temperature conditions.

Generally, at low temperatures, the flexibility of the rubber of the diaphragm decreases, the viscosity of the brake fluid increases, etc., so the speed of brake fluid pressure change during anti-skid operation slows down, making it impossible to perform good anti-skid control.

By providing a temperature-sensitive valve in the air passage, the present invention reduces the resistance of air in and out at low temperatures, accelerates the change in air pressure in the servo motor section, and prevents the drop in the speed of change in fluid pressure in the conventional system. An object of the present invention is to provide an actuator for anti-skid control that can maintain a substantially constant hydraulic pressure speed over a wide range of temperatures and enable good anti-skid control.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment, in which numeral 1 denotes an actuator comprising a main body 2 and a casing 3 fixed to it.

An input hole 4 for fluid communication with a master cylinder (not shown), a check ball 5, a plunger 6 in contact with the ball 5, and an output hole 7 for fluid communication with a wheel cylinder (not shown) are installed on the main body 2, and an atmosphere switching A solenoid valve 8 is provided. On the other hand, the inside of the casing 3 is divided into a variable pressure chamber 11 and a constant pressure chamber 12 by a diaphragm 9 and a power piston 10 connected thereto.

The variable pressure chamber 1; 1 can communicate with the constant pressure chamber 12 via a passage 13 in the main body 2, an electromagnetic valve 8, a valve 14, and a conduit 15. Further, the constant pressure chamber 12 is constantly in communication with an intake manifold of the engine (not shown) through a port 16, and springs 17 and 18 are tensioned inside, and the plunger 6 pushes the ball 5 against the power piston 10 to open the cut valve. It is biased in the direction. The electromagnetic valve 8 also includes a filter 19 through which the atmosphere passes, a plunger 20 that is reciprocated by a solenoid, and a passage 1 that operates in conjunction with the plunger 20.
3 and a chamber 21 provided in the main body 2, and is normally urged by a spring to close the communication between the passage 13 and the atmosphere by being pressed against the valve seat 22 on the electromagnetic valve side. is provided.

Further, a bimetal 24 is installed in the chamber 21, with one end fixed to the main body 2 and the other end fixed to the valve 14. The bimetal 24 senses the ambient temperature and operates to open and close the valve 14. At room temperature, the valve 14 is closed.
is closed as shown, and the chamber 21 and the conduit 15 are communicated through a small hole 25 provided in the valve 14, and the valve 14 is opened by the operation of the bimetal 24 at low temperatures. Next, to explain the operation of the first embodiment configured as described above, first, in the case shown in the figure, the negative pressure in the constant pressure chamber 12 is applied to the conduit 15 and the small hole of the valve 14 at room temperature.
5, the chamber 21, the gap between the valve body 23, and the passage 13 to the variable pressure chamber 1
1, and both chambers 11 and 12 are at negative pressure.

When the brake pedal (not shown) is stepped on here, the master cylinder pressure passes through the input hole 4, the cut valve opened by the ball 5, the pressure reduction chamber 26, and the output hole 7, and reaches the wheel cylinder (not shown), thereby performing braking. Next, when excessive deceleration of the wheel is sensed and an anti-slip signal is output, the solenoid valve 8 is activated, and the plunger 20 moves the valve body 23 downward in the drawing to close the communication between the passage 13 and the chamber 21.

Therefore, the communication between the variable pressure chamber 11 and the constant pressure chamber 12, which is always under negative pressure, is cut off, and the atmosphere enters the variable pressure chamber 11 and reaches the valve seat 22 and the valve body 23!
It flows through the gap and passage 13. As a result, the transformation chamber 1
The power piston 10 is pushed from the illustrated position by the differential pressure between the power piston 1 and the constant pressure chamber 12 and moves to the right against the springs 17 and 18.

Therefore, the plunger 6 is no longer resisted by the power piston 10, so it similarly moves to the right due to the brake oil pressure, and the ball 5 is no longer held down by the plunger 6, so it similarly moves to the right and hits the valve seat. The cut valve closes. Therefore, communication between the decompression chamber 26 and the input hole 4 is cut off. Thereafter, the plunger 6 is further moved to the right by brake hydraulic pressure from a wheel cylinder (not shown) that enters through the output hole 7, so that the volume of the decompression chamber 26 increases. As the volume of the decompression chamber 26 increases, the brake oil pressure on the wheel cylinder side decreases, the excessive deceleration of the wheels is released, and the rotational speed of the wheels is restored again. The above operations are repeated to perform the anti-skid action. The above effect occurred at room temperature, but at low temperatures, the viscosity of the brake oil increases, so it takes time to reduce the pressure during the pressure reduction stroke, and the brake pressure does not increase as much during the pressure recovery stroke. .

In the first embodiment of the present invention, a valve 14 is provided to change the air passage area of the conduit 15, and when the temperature is low, the bimetal 2
4 opens the valve 14 to widen the opening area of the conduit 15, reduce the resistance of the negative pressure air flowing into the variable pressure chamber 11, quickly change the differential pressure between the variable pressure chamber and the constant pressure chamber, and change the liquid pressure. This is to prevent speed reduction.

In the first embodiment shown in FIG. 1 described above, the valve body 23 closes the communication between the passage 13 and the chamber 21 by the operation of the solenoid valve 8 during the pressure reduction stroke (when releasing the lock). The male bimetal 24) does not work, but the depressurization stroke (
When applying negative pressure to the variable pressure chamber 11), the valve body 23 is connected to the passage 1.
3 and the chamber 21, so that the temperature sensitive valve is activated.

Next, FIG. 3 shows a second embodiment, which differs from FIG. 1 in the valve body 23 of the solenoid valve 8, which closes the opening of the conduit 15 on the pressure transformation chamber 11 side when an anti-skid signal is issued, and The difference is that the inlet of the variable pressure chamber 11 is opened and closed by a valve 14 which is a sensitive valve. In this embodiment, the valve 14 opens the inlet of the variable pressure chamber 11 during both the pressure reduction stroke and the pressure recovery stroke when the temperature is low, so the temperature range response valve acts in both pressure reduction and pressure recovery.
Next, FIG. 4 shows a third embodiment, which differs from FIGS. 1 and 2 in that the valve body 23 of the solenoid valve 8 is designed to open and close the opening of the conduit 15, but it Valve 14 of the valve is in chamber 2
The difference is that the opening/closing of the air inlet hole to 1 is controlled. In this embodiment, the atmospheric inlet is open at low temperatures, but since the valve body 23 is in contact with the valve seat 22 during the pressure recovery stroke, the temperature range response valve operates only during the pressure reduction stroke.

Since the present invention is configured as explained in detail above,
As shown in Figure 2, in the case of low temperatures, conventionally the brake fluid pressure does not drop as much as A at the pressure reduction stroke compared to a at room temperature, and it rises just as much as B at the pressure recovery stroke compared to b at room temperature. However, in the present invention, the brake fluid pressure drops quickly as shown in a during the pressure reduction stroke, and rises quickly as shown in b during the pressure recovery stroke.

Further, regarding the power piston differential pressure, in the present invention, in the pressure reduction stroke, the pressure difference is as large as C2 at a low temperature compared to the room temperature C1, and in the return pressure stroke, it is as small as 4 at a low temperature compared to the room temperature d1.

In other words, when the temperature is low and the viscosity of the brake fluid is high, the air moves in and out of the variable pressure chamber faster to speed up the movement of the power piston.
In addition, in the opposite case, the temperature sensitive valve is closed, the air passage area is reduced and the movement of the power piston is slowed down, and the pressure reduction speed and pressure recovery speed on the wheel cylinder side can be kept at a constant value that is not affected by the viscosity of the brake oil. , good anti-skid control is possible.

[Brief Description of the Drawings] Fig. 1 is a sectional view of an anti-skid control actuator showing an embodiment of the present invention, Fig. 2 is a diagram showing the relationship between brake fluid pressure and power piston differential pressure, and time. 3 and 4 are sectional views of anti-skid actuators of different embodiments from FIG. 1, respectively. Explanation of the main parts of the figure, 1...actuator,
5... Check ball (cut valve), 6...
... Plunger, 8 ... Atmosphere switching solenoid valve, 1
0... Power piston, 11... Variable pressure chamber, 12... Constant pressure chamber, 14... Valve, (temperature sensitive valve), 15... ...conduit, 23...
... Valve body, 24 ... Bimetal, (temperature sensitive valve), 25 ... Small hole, 26 ... Decompression chamber.

Claims (1)

[Claims] 1 Brake master cylinder pressure is sent to the wheel cylinder via the cut valve to perform brake braking, and when excessive deceleration of the wheel is detected, communication with the constant pressure chamber that is always negative pressure is cut off, allowing atmospheric air to flow in. Atmospheric air flows into the variable pressure chamber, which moves the power piston and closes the cut valve.
An air passage connecting the constant pressure chamber and the variable pressure chamber in an anti-skid control device that reduces the wheel cylinder pressure and restores the rotational speed of the wheel by increasing the circuit volume from the cut valve to the wheel cylinder. and/or a temperature sensitive valve is installed in a passage connecting the variable pressure chamber and the atmosphere, and the passage area changes depending on the temperature, and when the temperature is low, the temperature sensitive valve opens to increase the passage area and allow air to enter and exit the variable pressure chamber. The movement of the power piston during the pressure reduction stroke and/or pressure recovery stroke of the wheel cylinder pressure is increased, the temperature sensitive valve is closed at normal temperature, the air passage area is reduced, and the wheel cylinder pressure is reduced during the pressure reduction stroke. and/or by slowing down the movement of the power piston during the pressure recovery stroke, the pressure reduction and/or pressure recovery speed of the wheel cylinder pressure is made to be a constant value that is not affected by the viscosity of the brake fluid. Actuator for anti-skid control.