JPH0251785B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a brake fluid pressure control device for automobile brakes.

In automobiles, a hydraulic pressure holding valve is installed in the brake hydraulic pressure circuit from the master cylinder to the wheel cylinder in order to easily maintain the brakes on a slope and start on a slope. (See Publication No. 55-21250).

In addition, in automobile braking systems, a rear wheel hydraulic pressure control valve is installed to control the distribution of hydraulic pressure supplied to the front and rear wheels during braking, in order to prevent dangers such as oscillations caused by front wheels locking up during sudden braking. It goes without saying that it must be established (for example,
(See Publication No. 18249).

Conventionally, there are two types of rear wheel hydraulic pressure control valves: one is a cut valve type that reduces the pressure increase to zero when the rear wheel brake hydraulic pressure reaches a certain value, and the other is a cut valve type that reduces the pressure increase to zero when the rear wheel brake hydraulic pressure reaches a certain value. Since then, rear brakes have been equipped with a proportioning valve type that reduces hydraulic pressure proportionally.

The present invention provides a brake hydraulic pressure control device that has two functions, a hydraulic pressure holding valve and a rear wheel hydraulic pressure control valve, which have completely different properties as described above, thereby reducing the number of parts and assembly man-hours. miniaturization of
The purpose is to significantly reduce weight and cost. Specifically, it is a brake hydraulic pressure control device that has two functions: a hydraulic pressure holding valve and a cut valve type rear wheel hydraulic pressure control valve. The first object is to provide a brake hydraulic pressure control device, and the second object is to provide a brake hydraulic pressure control device which further has the function of a proportioning valve type device in addition to the first object.
This is the purpose of

The invention will now be described with reference to illustrated embodiments.

In FIG. 1, reference numeral 1 denotes a main body, and a valve chamber 3 is formed in the main body 1, and a valve chamber 3 is provided with play so that a ball 2 can freely roll in the front and back direction.The rear and front ends of the valve chamber 3 are connected to a master cylinder. Hydraulic inlet port 4 from and hydraulic outlet port 5 to rear wheel master cylinder
is connected to.

The bottom surface of the valve chamber 3, that is, the ball rolling surface, has a substantially horizontal flat surface 3a at the rear and an upwardly inclined surface 3b at the front, and the valve chamber 3 has balls at its front and rear ends. A rear seal 6 and a front seal 7 are provided, with which the ball 2 comes into contact and closes the inlet port 4 side and the outlet port 5 side when the ball 2 is moved rearward and forward.

A push rod 8 is built into the rear part of the valve chamber 3 so as to be slidable in the front and back direction, and a camshaft 9 is provided at the rear of the push rod 8. A lever 10 fixed to the camshaft 9 is connected to a clutch pedal by a cable 11. Alternatively, when the clutch is connected to a clutch operation system such as a clutch release fork, and the clutch pedal is not depressed, the push rod 8 is projected forward from the rear seal 6 by the camshaft 9 as shown in the figure, pushing the ball 2 forward, and the clutch is released. In the clutch-off state in which the pedal is depressed, the push rod 8 is moved to a position retracted rearward from the rear seal 6 by a spring 8a.

12 is a return spring for the lever 10. Reference numeral 13 denotes a cylinder chamber whose one end communicates with a hydraulic passage extending from the front seal 7 to the outlet port 5, and a piston 14 is fitted in the cylinder chamber 13.

The piston 14 is configured such that rear wheel braking hydraulic pressure acts on one end surface 14a, and hydraulic pressure within the valve chamber 3 acts on the other end surface 14b.
The area A of the piston 14 and the area B of the other end surface 14b have a relationship of A>B, and when the rear wheel braking hydraulic pressure P ₁ and the valve chamber hydraulic pressure P ₂ are equal, the area ratio of both ends of the piston 14 is B/A. As shown in the figure, the piston 14 is held in the most retracted position by the biasing force of the spring 15.

In the above configuration, when the clutch pedal is depressed while the brake pedal is depressed on an uphill road, braking fluid pressure is supplied from the master cylinder to the front wheel cylinder, and from the master cylinder to the inlet port 4, valve chamber 3, and outlet port 5. Braking fluid pressure is supplied to the rear wheel cylinder through the brake, and the brake is put into a braking state. When the clutch pedal is depressed, the lever 10 and camshaft 9 are rotated in the direction of the arrow via the cable 11, and the push rod 8 is retracted to the rear of the rear seal 6 by the spring 8a. Then, since the flat surface 3a is tilted rearward and downward due to the inclination of the vehicle body due to the uphill road, the ball 2 rolls rearward under its own weight and hits the rear seal 6, closing the inlet port 4 side.

When you take your foot off the brake pedal in this state, the braking fluid pressure on the front wheels is released, but the fluid pressure being supplied to the rear wheel cylinders cannot return to the master cylinder and remains in the braking state.

From this state, when you release the clutch pedal while depressing the access pedal, the lever 10 and the camshaft 9 rotate in the opposite direction of the arrow in conjunction with the engagement of the clutch, and the push rod 8
protrudes forward and pushes the ball 2 to move it forward, the brake fluid pressure is released, and a smooth start on a slope can be performed.

On the other hand, during braking, when the deceleration α of the vehicle reaches a predetermined value, the ball 2 rolls forward on the inclined surface 3b due to inertia force, comes into contact with the front seal 7, and exit port 5
side, and stops any further supply of hydraulic pressure from the master cylinder side to the rear wheel side.

The point at which the ball 2 contacts the front seal 7 is determined by the deceleration α of the vehicle and the inclination angle θ of the inclined surface 3b, so by appropriately setting the inclination angle θ of the inclined surface 3b, Hydraulic pressure supply from the master cylinder side to the rear wheel side can be reliably stopped at a desired deceleration.

The rear wheel brake fluid pressure characteristics up to this point are as shown in the range of Fig. 2. After the point a when the ball 2 contacts the front seal 7, even if the fluid pressure from the master cylinder increases, The increase in wheel brake fluid pressure becomes zero, and it functions as a cut valve, preventing the rear wheels from locking up.

Even after the ball 2 comes into contact with the front seal 7, the hydraulic pressure on the master cylinder side increases, and the hydraulic pressure supplied to the front wheels increases.

Therefore, the hydraulic pressure P ₂ in the valve chamber 3 communicating with the master cylinder side increases, and the difference with the rear wheel side hydraulic pressure P ₁ gradually increases, P ₁ = (P ₂ ×B/A) -F (where F is the spring force of the spring 15), when _P2 becomes larger, the piston 14 moves forward and sends the fluid in the cylinder chamber 13 to the rear brake side.
Rear wheel brake fluid pressure increases non-linearly.

The above rear wheel brake fluid pressure characteristics are as shown in the range of Fig. 2, and as the master cylinder fluid pressure increases, the rear wheel brake fluid pressure decreases due to the ball 2 coming into contact with the front seat 7 and the fluid from the master cylinder increasing. After the pressure is cut off at point a, the hydraulic pressure in the master cylinder reaches a predetermined point b.
In the above range, by operating the piston 14 using differential pressure, it is possible to obtain a characteristic that has the function of a so-called proportioning valve that proportionally lowers and applies hydraulic pressure to the rear wheel side, thereby locking the front wheels of the rear wheels. It is something that can be prevented.

In FIG. 2, the slope after point b is determined by the area ratio B/A of both end surfaces of the piston 14 and the spring constant of the spring 15.

When the vehicle stops due to braking and the hydraulic pressure in the master cylinder is released, the ball 2 rolls backward on the inclined surface 3a, and the difference between P ₁ and P ₂ disappears, so the piston 1
4 is returned to its original position by a spring 15.

To summarize the above, if the structure is such that the cylinder chamber 13, piston 14, spring 15, etc. are omitted in FIG. Therefore, the cylinder chamber 13,
By adding the piston 14, spring 15, etc., it is possible to create a brake hydraulic pressure control device that has two different functions: a hydraulic pressure holding valve function and a proportioning valve function.

As described above, according to the present invention, by configuring the rolling surface of the ball to be a substantially horizontal flat surface at the rear and an upwardly sloped surface at the front, one ball can be freely mounted in a single valve chamber. By just doing this, you can obtain a hydraulic control valve that has both the functions of a brake hydraulic pressure holding valve that maintains braking on uphill roads and a rear wheel hydraulic pressure cut valve that detects deceleration during sudden braking. By combining a piston that is operated by the difference in hydraulic pressure between the rear wheel side and the master cylinder side after hydraulic pressure cut, it can also have a proportioning valve function, and in either case, the number of parts can be reduced. This can bring about a great deal of practical effect, such as reducing the number of installation steps and the number of installation steps, as well as reducing the size, weight, and cost of the device.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a diagram showing rear wheel brake fluid pressure characteristics during sudden braking by the device of the present invention. 1...Main body, 2...Ball, 3...Valve chamber,
4... Inlet port, 5... Outlet port, 6... Rear seal, 7... Front seal, 8... Push rod, 13... Cylinder chamber, 14... Piston.

Claims (1)

[Scope of Claims] 1. A valve chamber is provided in the main body in which a ball can be freely rolled in the front-rear direction, and the ball rolling surface of the valve chamber is a substantially horizontal flat surface in the rear part and a substantially horizontal flat surface in the front part. The front end of the valve chamber has a brake fluid pressure inlet passage that communicates with the master cylinder side, and the front end of the valve chamber has a brake fluid pressure outlet passage that communicates with the rear wheel brake side. When the ball rolls rearward, the brake fluid pressure inlet passage is closed, and when the ball rolls forward, the brake fluid pressure outlet passage is closed. A braking hydraulic pressure control device for an automobile brake, characterized in that a push rod is provided to press and hold a press rod in a forward position so as not to block a pressure inlet passage. 2 A valve chamber is provided in the main body in which the ball can be rolled back and forth, and the ball rolling surface of the valve chamber is an almost horizontal flat surface at the rear and an upward slope at the front. A brake fluid pressure inlet passage that communicates with the master cylinder side is provided at the rear end of the valve chamber, and a brake fluid pressure outlet passage that communicates with the rear wheel brake is provided at the front end of the valve chamber. When the ball rolls forward, the brake fluid pressure inlet passage is closed, and when the ball rolls forward, the brake fluid pressure outlet passage is closed, and when the clutch is turned on, the ball closes the brake fluid pressure inlet passage. A push rod is provided to press and hold it in the forward position,
In addition, a cylinder chamber is provided in the main body, which bypasses the vicinity of the brake fluid pressure inlet passage of the valve chamber and communicates with the brake fluid pressure outlet passage, and the cylinder chamber has a hydraulic pressure in the valve chamber relative to the hydraulic pressure in the brake hydraulic pressure outlet passage. 1. A braking fluid pressure control device for an automobile brake, characterized in that a piston is provided, which is actuated by the differential pressure to push fluid in a cylinder chamber to a braking fluid pressure outlet passage when the pressure becomes higher than a predetermined value.