JPH0217381B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a brake hydraulic pressure control device, and more particularly to a brake hydraulic pressure control device that allows braking characteristics when the vehicle is empty to be different from braking characteristics when the vehicle is loaded.

This type of brake fluid pressure control device is normally biased in one direction by a spring and held in a non-operating position, and is activated when the brake fluid pressure exceeds a predetermined value to increase the brake fluid pressure on the input side. A known model is equipped with a proportion valve that increases the output brake fluid pressure at a low pressure increase rate compared to the vehicle pressure, and a deceleration sensing valve that senses the deceleration of the vehicle and opens and closes a passage depending on the magnitude of the deceleration. It is being In a brake fluid pressure control device having such a configuration, when a predetermined deceleration is obtained with a low brake fluid pressure, such as when the vehicle is empty, the deceleration detects the valve and closes the deceleration sensing valve to reduce the fluid pressure. On the other hand, when the specified deceleration cannot be obtained even when the brake fluid pressure is relatively high, such as when loading a vehicle, the deceleration sensing valve is kept open to obtain high fluid pressure. Utilizing the large and small hydraulic pressures obtained in this way, when the vehicle is empty, the length of the spring that biases the proportion valve is kept long and the proportion valve is operated with low brake fluid pressure, and when the vehicle is loaded, the spring that biases the proportion valve is activated. The set length of the brake is shortened so that the proportion valve operates with high brake fluid pressure, thereby providing braking characteristics suitable for both when the vehicle is empty and when the vehicle is loaded.

However, with the conventional brake fluid pressure control device that changes the timing of the proportion valve operation by changing the set length of the spring as described above, it is possible to adjust the timing when the vehicle is idle by simply changing the set length of the spring. There are certain limitations in obtaining the biasing force of the proportion valve that is suitable for loading the vehicle, and the braking characteristics when the vehicle is empty and the braking characteristics when the vehicle is loaded must be set separately and freely. It was difficult.

In addition, conventional deceleration sensing valves used to obtain control pressure according to loading conditions have a valve seat located forward in the direction of operation due to the inertia of the valve body, as described above, and the valve body moves due to inertia. Therefore, since the valve body was configured to be seated on the valve seat, the seating timing of the valve body tends to vary due to external factors such as vibration of the vehicle, especially when the vehicle is empty, and therefore deceleration This had the disadvantage that the pressure of the brake fluid sealed in the flow path downstream of the sensing valve varied, resulting in unstable vehicle empty characteristics.

In view of these points, the present invention has the proportion valve biased in one direction receive hydraulic pressure in accordance with the loading state obtained by the valve mechanism of the deceleration sensing valve to bias the proportion valve in the bias direction. By forming a pressure-receiving surface that is biased in the opposite direction to the pressure-receiving surface, and varying the biasing force of the proportion valve by the hydraulic pressure acting on this pressure-receiving surface, the braking characteristics when the vehicle is empty and when the vehicle is loaded are different from conventional ones. This allows for more flexible settings, and
By providing the valve seat of the deceleration sensing valve at the rear in the direction of movement of the valve body due to inertia, empty vehicle characteristics can be particularly stabilized.

The present invention will be described below with reference to the illustrated embodiments.
In FIG. 1, 1 is a proportion valve provided in the casing 2, 3 is a deceleration sensing valve provided in the casing 2, and the proportion valve 1 is configured so that liquid is supplied to the hole 4 of the casing 2 by a sealing member 5. Plunger 6 fitted tightly and slidably
It is equipped with This plunger 6 is biased leftward by a spring 8 elastically loaded between the right end surface of a large diameter portion 6a formed in the middle portion and the left end surface of a plug 7 that closes the right end opening of the hole 4. There is. A rod 9 is provided at the left end of the plunger 6, and the rod 9 is connected to the hole 4 when the plunger 6 is urged leftward by the spring 8 and is in the non-operating position shown in FIG. It protrudes into the chamber 11 by loosely fitting through the provided through hole 10. Inside this chamber 11 is a valve body 1 pushed up by the rod 9.
The valve body 12 is urged by a spring 13 so as to be seated on a valve seat 14 formed around the through hole 10. is set to a large value, so that under normal conditions, the plunger 6 is held in the non-operating position shown, and the valve body 12 is held apart from the valve seat 14 by the rod 9.

Reference numeral 15 denotes an input hole formed in the casing 2, which is connected to a master cylinder (not shown) and communicates with a chamber 16 in which the spring 8 is housed. This chamber 16 communicates with the chamber 11 housing the valve body 12 through a passage 17 formed in the casing 2, and further through a chamber 18 formed around the through hole 10 and the stepped portion of the plunger 6 and rod 9. It communicates with the output hole 19. This output hole 19 is connected to a rear wheel cylinder (not shown).

The deceleration sensing valve 3 includes a chamber 20 and a ball-shaped valve body 21 rotatably housed within the chamber 20. It is usually located at the lower part of the vehicle body in the direction of inclination. The upper part of the chamber 20 in the direction of inclination that accommodates the valve body 21 communicates with the chamber 11 that accommodates the valve body 12 of the proportion valve 1 via the valve mechanism 22 and the passages 23 and 17. The lower part is connected to the plunger 6 via the valve seat 24 and the passage 25 on which the valve body 21 is seated due to its own weight.
It communicates with a chamber 26 formed at the left end of the large diameter portion 6a.

As shown in an enlarged view in FIG. 2, the valve mechanism 22 includes a disk-shaped plate body 28 having a through hole 27 formed approximately in the central axis thereof, and a passageway surrounding the plate body 28. The above-mentioned through hole 27 is closed on the 23 side by its own elasticity.
The valve body 30 includes an elastic body 29 made of rubber or the like having a flexible portion 29a that closes the passage 23, and a spring 31 that biases the valve body 30 in one direction to normally close the passage 23. Therefore, this valve mechanism 22
is opened when the brake fluid pressure in the chamber 11 exceeds a predetermined value and introduces the brake fluid pressure into the chamber 20, and when the brake fluid pressure in the chamber 11 decreases thereafter, the brake fluid pressure in the chamber 20 is opened. The pressure fluid introduced into the through hole 2
7 and the flexible portion 29 curved by the pressure thereof.
It is discharged to the chamber 11 side through the gap between a and the plate 28. Note that a valve mechanism having the same function can be constructed by providing two parallel branch passages in the middle of the passage 23 and providing each branch passage with a check valve that allows flow in opposite directions. .
Further, in FIG. 2, 32 is a retainer that receives the spring 31, 33 is a hole drilled in the shaft of this retainer, 34 is a stop ring that supports the retainer, and in FIG. 1, 35 is an air vent valve. It is.

In the above configuration, when the brake pedal (not shown) is depressed to generate brake fluid pressure in the master cylinder, the brake fluid pressure is transmitted from the input hole 15 to the chamber 16, the passage 17, the chamber 11, the through hole 10, and the chamber 1.
8 to the output hole 19, and further to the rear wheel cylinder. At the beginning of braking when the brake fluid pressure is low, the plunger 6 of the proportion valve 1 does not operate, and as shown by the straight line A _in FIG. Brake fluid pressure that is substantially the same as the brake fluid pressure that is introduced into the front wheel cylinder connected to the front wheel is introduced.

When the vehicle is empty, the relatively low brake fluid pressure causes the deceleration of the vehicle to exceed a predetermined value, as shown at point a in FIG.
due to inertia, it rolls to the left in FIG. 1 and leaves the valve seat 24. When the brake fluid pressure increases in this state and reaches the fluid pressure shown at point b in FIG. 3, the pressure fluid pushes open the valve body 30 of the valve mechanism 22 and flows into the chamber 20 from the passages 17 and 23. , further flows into the chamber 26 through the gap between the valve body 21 and the valve seat 24 and the passage 25. As described above, a part of this chamber 26 is formed on the left end side of the large diameter part 6a of the plunger 6, so the brake fluid pressure introduced here applies a rightward biasing force to the plunger 6 against the spring 8. Grant.

Then, when the brake fluid pressure further increases and becomes the fluid pressure shown in FIG. The resultant force of the biasing force due to the brake fluid pressure acting on the left end surface of the plunger 6 is the biasing force that biases the plunger 6 to the left. The force becomes larger than the resultant force, and the plunger 6 is moved to the right and the valve body 1
2 is seated on the valve seat 14. As a result, the above-mentioned through hole 1
The increase in the brake fluid pressure introduced into the rear wheel cylinder via the brake fluid pressure is stopped.

After this, when the brake fluid pressure further increases, the force acting on the left end surface of the plunger 6 does not increase due to the seating of the valve body 12, but the pressure in the chamber 16 does not increase.
At the same time, the force applied by the brake fluid pressure introduced into the chamber 26 increases, and at this time, the plunger 6 on the chamber 16 side
Since the pressure-receiving area of
2 is removed from the valve seat 14. When the valve body 12 is removed from the valve seat 14, the brake fluid pressure acting on the rear wheel cylinder, that is, on the left end surface of the plunger 6, increases, and the plunger 6 is moved to the right to close the valve body 12. The person is seated on the seat 14. In this way, the plunger 6 reciprocates from side to side as the brake fluid pressure increases, and adjusts the brake fluid pressure introduced into the rear wheel cylinder according to the pressure receiving area difference.
Increase P _OUT at a lower rate of increase than the brake fluid pressure P _IN on the input side (line B in Figure 3).

In contrast to the above-mentioned braking characteristics when the vehicle is empty, when the vehicle is loaded, the deceleration of the vehicle is small even if the brake fluid pressure pushes open the valve body 30 of the valve mechanism 22 (point b in Fig. 3). However, the valve body 21 continues to be seated on the valve seat 24 due to its own weight. Then, in this state, the valve body 30 is pushed open, and the brake fluid pressure is applied to the chamber 2.
0, this pressure fluid presses and holds the valve body 21 against the valve seat 24 due to the pressure difference between the pressure in the chamber 20 and the pressure in the passage 25 and the chamber 26, so that the brake fluid pressure increases thereafter. Even if the deceleration of the vehicle exceeds a predetermined value, the valve body 21 will not separate from the valve seat 24. In this state, no brake fluid pressure is introduced into the chamber 26 on the left end side of the large diameter portion 6a, so the force to move the plunger 6 to the right is obtained by the brake fluid pressure acting on the left end surface of the plunger 6. Therefore, unlike when the vehicle is empty, the plunger 6 will not move to the right even if the brake fluid pressure rises to the above-mentioned point c.
At this time, if the pressure receiving area at the right end of the large diameter portion 6a facing the chamber 16 is set larger than the pressure receiving area at the left end of the plunger 6, the plunger 6 will not operate, and in this case, the pressure generated in the master cylinder Brake fluid pressure that is substantially the same as that of the rear wheel cylinder can be introduced into the rear wheel cylinder (the third
Figure straight line A′). On the other hand, if the pressure-receiving area is set oppositely, the proportion valve 1 can start operating at a much higher brake fluid pressure (point d in Figure 3) than when the vehicle is empty, depending on the difference. (see straight line C in FIG. 3), and in either case, braking characteristics suitable for loading a vehicle can be obtained.

FIG. 4 shows an embodiment using a hydraulic pressure sensing valve having another configuration. In this embodiment, the valve mechanism 22 is omitted, and instead, a piston 41 is inserted into a hole 40 communicating with the passage 25. A rod 42 is attached to the piston 41 to push up the valve body 21, and a spring 44 is loaded between the piston 41 and a plug 43 that closes the hole.
Normally, the valve body 21 is moved to the valve seat 24 by the rod 42.
This was to prevent the person from sitting on the seat. Note that the other configurations are the same as in FIG. 1.

In this embodiment, the brake fluid pressure is transferred to the chamber 20 and the passage 2 via the passage 23 as soon as this occurs.
5 and the aforementioned chamber 26, and its brake fluid pressure acts on the left end surface of the piston 41 to try to move it to the right. Therefore, when the vehicle is empty, if the piston 41 moves to the right and a predetermined deceleration is obtained before the valve body 21 seats on the valve seat 24, the valve body 21 will be seated on the valve seat 24. Since it has already rolled to the left due to inertia before the piston 41 moves to the right, the valve body 21 will not be seated on the valve seat 24 even if the piston 41 then moves significantly to the right. Braking characteristics when the vehicle is empty can be obtained.

On the other hand, when loading a vehicle, before the valve body 21 rolls to the left due to inertia, the piston 41 moves to the right due to brake fluid pressure, and the valve body 21 moves toward the valve seat 24.
Since the valve body 21 is held in contact with the valve seat 24 by the subsequent rise in brake fluid pressure, braking characteristics during loading can be obtained in the same manner as in the above-described embodiment.

As described above, in the normal state, the present invention is biased in one direction and held in a non-operating position, and is activated when the brake fluid pressure exceeds a predetermined value to output an output in response to an increase in input hydraulic pressure. A proportion valve that increases fluid pressure at a low rate of increase, a pressure receiving surface formed on the plunger of this proportion valve that receives brake fluid pressure and urges the plunger in a direction opposite to the above-mentioned urging direction, and this pressure receiving surface. A valve body is provided in a passage that introduces the brake fluid pressure into the surface and moves by its own inertia when the deceleration of the vehicle exceeds a predetermined value, and a valve seat is provided on the rear side in the direction of movement. Because it is equipped with a valve mechanism consisting of a valve mechanism, it is possible to more freely adjust the braking characteristics between empty and loaded than with conventional spring set lengths that change depending on the size of the pressure-receiving surface and the control pressure. In addition, since the pressure receiving surface of the plunger is set so that the plunger is biased in the opposite direction by the hydraulic pressure introduced from the valve mechanism, the length of the plunger can be set short, and The pressure-receiving area can be freely adjusted, and furthermore, the reliable operation of the valve mechanism can particularly stabilize empty car characteristics.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention, FIG. 2 is an enlarged view of the main part of FIG. 1, FIG. 3 is a characteristic curve diagram showing braking characteristics, and FIG. FIG. 2 is a vertical cross-sectional view of main parts showing an embodiment of the present invention. 1...Proportion valve, 2...Casing, 3...Deceleration sensing valve, 6...Plunger, 6
a... Large diameter part, 8... Spring, 12... Valve body, 2
3, 25...Aisle, 26...Room.

Claims (1)

[Claims] 1 Under normal conditions, it is biased in one direction and held in the non-operating position, and is activated when the brake fluid pressure exceeds a predetermined value, increasing the output fluid pressure at a low rate of increase as the input fluid pressure increases. a proportion valve formed on the plunger of this proportion valve, which receives brake fluid pressure and urges the plunger in a direction opposite to the urging direction; and a pressure receiving surface that introduces the brake fluid pressure into the pressure receiving surface. The valve mechanism includes a valve body that is installed in a passage where the vehicle moves and that moves by its own inertia when the deceleration of the vehicle exceeds a predetermined value, and a valve seat that is provided on the rear side in the direction of movement. A brake fluid pressure control device featuring: