JPS62273154A - Skid preventing device - Google Patents

Abstract

PURPOSE:To make it possible to exhibit the pumping capability suitably adapted for brake pressure so that the braking distance on a road surface having a high frictional coefficient is shortened, by forming a plunger therein with a high-pressure hydraulic passage for allowing working fluid to branch off from a hydraulic passage during movement of the plunger. CONSTITUTION:Upon pressure rising stroke during anti-skid operation, working fluid flows from the left to the right through a flow passage 40 in a plunger 35. After passing through an orifice 35, the working fluid is fed into a cylinder chamber 17, the flow rate of the working fluid being limited. On the contrary, when the hydraulic pressure of a system pressure communication passage 44 becomes high so that it overcomes the pressing force of a spring 43, the plunger 35 is moved leftward so that the right end of the plunger 35 is separated from a seat surface between second and third bore sections 32, 33 in a pump piston 30. Further, the working fluid branches off and flows into a high pressure hydraulic passage 41 just before the orifice 39 and merges in the third bore section 33 in the pump piston 30 by way of the outer peripheral section of the plunger 35 and the seat surface.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Field of Industrial Application] The present invention has a modified detection mechanism that detects acceleration and deceleration of wheel rotation, and prevents skids by raising and lowering brake fluid pressure. Regarding equipment.

[Conventional technology]

FIGS. 2 and 3 show a conventional example of a skid prevention device.

This device includes a hydraulic pressure modulation section B that lowers the brake fluid pressure in accordance with the detection by the lock detection section △ to a lock detection section that detects wheel lock, and a hydraulic pressure modulation section B that lowers the brake pressure that has been reduced to prevent skid. It is constructed by a pump section C, and is provided in the middle of a path for transmitting the hydraulic pressure generated by the master cylinder operated by the brake pedal to the brakes of each wheel.

To explain the above-mentioned lock detection section, reference numeral 1 in the figure is a rotating shaft that is linked to the wheels, and a flywheel 2 is provided on this rotating shaft 1 so as to be movable in the axial direction. 1 and flywheel 2 rotate @1
By means of a ball ramp mechanism 3 provided at the end of the rotor, it is possible to switch between an interlocking rotation state and a non-interlocking rotation state. That is, the above ball ramp m structure 3
SL.

A ramp member 5 having a ramp groove into which the ball 4 is fitted.
6 is fixed to the rotating shaft 1 side and the flywheel 2 side respectively, and the flywheel 2 is roughly pushed to the right in FIG. Lamp member 6 and rotating shaft 1
The lamp member 5 on the side is integrally connected via a ball 4.

In the lock detection section configured in this way, the rotating shaft 1 and the flywheel 2 rotate in conjunction with each other in a normal rotating state, and when the wheels are in a locked state, the rotating shaft 1
stops and the flywheel 2 tries to continue rotating due to its own inertial energy, so the ramp member 5.6
A ball 4 held between the two rotates them relative to each other while widening the mutual distance between them. When the ramp member 6 moves to the left in FIG. 3, the flywheel 2 also moves in the same direction and presses the lever 8.

Roughly speaking, when the lever 8 rotates clockwise around the fulcrum P in FIG. 3, the dump valve 9 is opened and the brake fluid is returned to the reservoir of the master cylinder via the return boat 11. , brake pressure decreases.

Further, in this state, the flywheel 2 is in an overrunning state with respect to the rotating shaft 1, but is decelerated by the action of the friction clutch 10 interposed between the flywheel 2 and the rotating shaft 1. Then, as the rotation of the rotating shaft 1 is restored, the flywheel 2 returns to its original position, the dump valve 9 returns to the closed state, and the ball ramp mechanism 3 returns to the standby state for the next operation.

During normal operation, the skid prevention device having the lock detection section A configured as described above transfers the brake fluid supplied from the mask-cylinder to the boat 12 to the chamber 13A of the pump section C, the communication passage 14, and the hydraulic pressure. Chamber 13B of modulator B, valve 1
On the other hand, when the wheels are locked, the dump valve 9 is opened by the action of the lock detection section A, and the liquid in the cylinder chamber 17 of the hydraulic pressure modulation section B is supplied to the brake cylinder from the boat 16 via the hydraulic pressure modulation section B. The pressure decreases, and as the pressure decreases, the piston 18 descends and the valve 15 is closed, thereby cutting off the supply of brake fluid to the brake cylinder and releasing the brake. Furthermore, in the pump section C, the pump piston 20 is moved up and down by the eccentric cam 19 provided at the rotation @1. As a result, the working fluid that has passed from the reservoir of the master cylinder through the chamber port 11 and inside the pump piston 2o is transferred to the valve 21,
The dump valve 9 is supplied into the cylinder chamber 17 via the outer circumference of the pump piston 20 and the communication path 22, and the rotary shaft 1 resumes rotation and starts rotating integrally with the flywheel 2 again. When the cylinder chamber 17 is closed again, the pressure inside the cylinder chamber 17 rises, causing the piston 18 to rise and the valve 15 to open, causing the boat 12 and the boat 1 to close.
6 is communicated again, and the supply to the brake cylinder is resumed.

[Problem that the invention seeks to solve]

By the way, the pump piston 20 of the conventional pump section C mentioned above
A liquid passage with a throttle is formed in the center of the shaft, but because the throttle is fixed, the flow ω is constant, and the pressure increase speed is not optimal for all road surfaces. That is, in the structure of the conventional pump piston 20, it is necessary to set the pump performance (restriction) suitable for slippery road surfaces (road surfaces with a low coefficient of friction), so a high f
On a road surface with a five-ring coefficient, there is a problem in that the pressure increase rate tends to be insufficient and the braking distance becomes short.

The present invention has been made in view of the above circumstances, and its purpose is to make the throttle in the pump piston variable in accordance with the hydraulic pressure of the brake system 11, thereby controlling the brake hydraulic pressure. To provide a skid prevention device capable of exhibiting suitable pumping capacity and greatly increasing the pumping capacity during anti-skid operation especially on a road surface with a high II ring coefficient, thereby shortening the braking distance.

[Means for solving problems]

In order to achieve the above object, the present invention provides a pump piston that is movably reciprocated inside a pump section, a plunger that is provided with a liquid passage inside the pump piston, and a plunger that is movably provided inside the pump piston. and the plunger, a spring is installed that presses the plunger against one side of the pump piston, and a brake fluid pressure is applied to the pump piston to push the plunger against the spring against the other side of the pump piston. A system pressure communication passage for movement is formed in the plunger, and a high-pressure liquid passage is formed in the plunger to divert the working fluid from the liquid passage when the plunger is moved.

[For production]

In the skid prevention device of the present invention, when the pressure in the brake system is low, the plunger is pressed against one side of the pump piston by the pressing force of the spring,
The working fluid passes through a fluid passageway inside the plunger. On the other hand, when the pressure in the brake system increases, it overcomes the pressing force of the spring and moves the plunger to the other side.
Along with the liquid passage, the working fluid also flows through the high-pressure liquid passage bypassed from the liquid passage, reducing pipe resistance and increasing pumping capacity.

(Example〕 Hereinafter, one embodiment of the present invention will be described based on FIG.

Note that FIG. 1 is a sectional view showing an example of a pump piston. In this embodiment, the pump piston shown in FIG. 1 is installed inside the pump section C in place of the pump piston 20 of the conventional example shown in FIG. Since they are similar, they will be given the same reference numerals and their description will be omitted.

The pump piston 30 has a first inner diameter portion 3 inside thereof.
1, and this first one is 1. A second inner diameter part 32 that is continuous to the second inner diameter part 31 and has a smaller diameter than the first inner diameter part 31; a third inner diameter part 33 that is continuous to the second inner diameter part 32 and has a smaller diameter than the second inner diameter part 32; It has a hollow cylindrical shape that is connected to the third inner diameter portion 33 and has a valve chamber 34 that accommodates the valve 21 .

The first and second inner diameter portions 3 of this pump piston 30
A hollow cylindrical plunger 35 is operatively attached to L 32 . This plunger 35 has first, second, and third outer diameter portions 36 and 3 whose outer circumferential portions are gradually reduced in diameter.
7.38, and a liquid passage 40 having an orifice 39 is formed inside the plunger 35.

Further, a high pressure liquid passage 41 is formed from a position immediately before the orifice 39 of the plunger 35 (the left end position of the orifice 39 in FIG. 1) to the outside. The fl! of the plunger 35 is located between the stopper 42 attached to the first inner diameter portion 31 of the pump piston 30 and one end of the plunger 1735. ! Plug the end into the above pump piston 3
A spring 43 that presses against the seat surface between the second and third inner diameter portions 32 and 33 of 0 is installed inside. Furthermore, the second inner diameter portion 32 of the first inner diameter portion 31 of the pump piston 30 is
A system pressure communication passage 44 communicating with the outside is formed on the side. Further, a communication hole 45 is formed from the valve chamber 34 of the pump piston 30 to the outer peripheral side. In addition, 4
6 is an O mounted on the first outer diameter portion 36 of the plunger 35.
The ring 47 is an O-ring mounted between the second outer diameter group 37 of the plunger 35 and the first inner diameter section 31 of the pump piston 30.

In the skid prevention device configured as described above, when the rotary shaft that has been in the locked state resumes rotation and starts rotating integrally with the flywheel again, and the dump valve closes, the pump piston 30 of the pump portion C Due to the reciprocating movement, the pressure in the cylinder seedling 17 begins to increase.

In this case, when the hydraulic pressure in the system pressure communication passage 44 is low,
The plunger 35 is moved by the pressing force of the spring 43.
Since the pump piston 30 is pressed against the seat l'l between the second and third inner diameter parts 32, 33, the working fluid in the pressure increasing process during anti-skid operation flows through the liquid passage 40 of the plunger 35 in FIG. flows from left to right,
After passing through the orifice 39, the third part of the pump piston 30
The cylinder chamber 1 is connected to the cylinder chamber 1 through the inner diameter portion 33, the valve 21, the valve chamber 34, the communication hole 45, the outer circumference of the pump piston 30, and the communication passage 22.
Supplied within 7 days. Therefore, the working fluid is throttled by the orifice 39 and its flow is limited.

On the other hand, when the hydraulic pressure in the system pressure communication passage 44 increases and overcomes the pressing force of the spring 43, the plunger 35 moves to the left in FIG. 30, the working fluid is separated from the seat surface between the second and third inner diameter portions 32 and 33 of the plunger 30, so the working fluid is diverted from just before the orifice 39 to the high-pressure liquid passage 41, and passes through the outer periphery of the plunger 35 and the seat surface. hand,
They merge at the third inner diameter section 33 of the pump piston 30.

Therefore, when the liquid pressure becomes higher than the predetermined pressure, the orifice 3
Since the working liquid also flows to the liquid passage 41 side when the pressure is high, the flow passage becomes wider than when the pressure is low, and the pumping capacity increases. This shortens the braking distance during anti-skid operation on a high-pressure road surface with a high friction coefficient.

〔Effect of the invention〕

As explained above, the present invention provides a pump piston that is movably reciprocated inside a pump section, a plunger that is provided with a liquid passage therein, and a plunger that is movably disposed inside the pump piston. A spring that presses the plunger against one side of the pump piston is installed between the pump piston and the pump piston, and brake fluid pressure moves the plunger to the other side of the pump piston against the spring. While the system pressure communication passage is formed in the plunger, a high-pressure liquid passage is formed in the plunger to divert the working fluid from the liquid passage while the plunger is moving. can be varied according to the brake system's hydraulic pressure, which allows the pump capacity to be adjusted to suit the brake hydraulic pressure, and significantly increases the pump capacity during anti-skid operation, especially on roads with high friction coefficients. Therefore, there is an effect that the braking distance can be shortened.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a pump section showing an embodiment of the present invention, Fig. 2 is a longitudinal sectional view of a conventional skid prevention device, and Fig. 3 is a sectional view taken along the line ■-■ in Fig. 2. . A...Lock detection section, B...Liquid pressure modulation section, C...Pump section, 30...Pump piston, 35... Plunger, 40...
...Liquid passage, 41...Liquid passage at high pressure, 43...
... Spring, 44 ... System pressure communication passage.

Claims (1)

[Claims] a lock detection unit that detects locking of the wheels; a hydraulic pressure modulation unit that lowers brake fluid pressure in accordance with detection by the lock detection unit;
In a skid prevention device consisting of a pump section that increases the brake fluid pressure that has decreased to prevent skid,
The pump section includes a pump piston that is movably provided therein, a plunger that has a liquid passage inside the pump piston, and a plunger that is movably disposed inside the pump piston. A spring is mounted to urge the plunger against one side of the pump piston, and a system pressure connection is provided to the pump piston for moving the plunger to the other side of the pump piston against the spring by the brake fluid pressure. A skid prevention device characterized in that a passage is formed in the plunger, and a high-pressure liquid passage is formed in the plunger to allow a working fluid to flow in a branched manner from the liquid passage when the plunger moves.