JPH0211468B2 - - 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, as mentioned above, it is necessary to apply an appropriate force to the proportion valve both when the car is empty and when the car is loaded by changing the set length of the spring, so the spring constants of the above springs were compared. Therefore, the pressure-receiving area of the piston that changes the set length of the spring in response to the hydraulic pressure from the deceleration sensing valve must be increased, and the piston must be made large. It had the disadvantage of being larger.

In view of these points, the present invention does not change the set length of the spring that biases the proportion valve, but instead changes the lift amount of the valve body of the proportion valve with respect to the valve seat. To provide a brake hydraulic pressure control device that can obtain the same effect as when changing the set length of the spring, thereby reducing the size of the mechanism required to change the lift amount. .

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 designed to prevent liquid from flowing into the hole 4 of the casing 2 by means of a sealing member 5. Plunger 6 fitted tightly and slidably
It is equipped with This plunger 6 is urged rightward by a spring 7 elastically mounted between the left end surface of a large diameter portion 6a formed at its right end and the casing 2. Small diameter portion 6b formed at the left end of the plunger 6
is slidably protruded into a chamber 8 connected to the hole 4 while being kept liquid-tight by a sealing member 9. A chamber 10 is formed within the large-diameter portion 6a of the plunger 6, and a valve body 11 housed within the chamber 10 is urged rightward in FIG. 1 by a spring 12. Above room 10
are passages 13 and 14 formed in the shaft portion of the plunger 6.
chambers 15 and 8 at both ends of the plunger, respectively.
A valve seat 16 on which the valve body 11 is seated closes the passage 13 is provided around a passage 15 communicating with the chamber 15. The chamber 8 on the small diameter portion 6b side of the plunger 6 communicates with a master cylinder (not shown) through an input hole 17 formed in the casing 2, and the chamber 15 at the other end communicates with a rear wheel side wheel cylinder (not shown) through an output hole 18. It's communicating.

A hole 19 is formed on the coaxial right side of the hole 4 so as to be continuous with this hole, and a sealing member 20 is installed in the hole 19.
The piston 21 is slidably fitted while maintaining liquid tightness. The left end of the piston 21 is loosely fitted through the passage 13 and the valve seat 16, and the valve body 11 is inserted into the left end of the piston 21.
A rod 22 is provided for pushing up the piston 21, and the piston 21 is biased toward the left in FIG. 1 by a spring 23. The biasing force of this spring 23 is
1, and the biasing force of spring 7 that biases plunger 6 is usually much larger than that of spring 12, so that the inoperative state shown in FIG. In this state, the plunger 6 and the piston 21 are held at the sliding end positions by the springs 7 and 23, respectively, and the valve body 11 is held at the sliding end position by the springs 7 and 23, respectively.
2 and is pushed up from the valve seat 16.
In this state, the lift amount L of the valve body 11 relative to the valve seat 16 is maximum, and as the piston 21 and rod 22 move to the right against the spring 23, the lift amount becomes smaller.
The stroke amount l of the piston 21 is set smaller than the lift amount L, so that a predetermined lift amount can be ensured even when the piston 21 is at the right-hand end.

The deceleration sensing valve 3 includes a chamber 25 and a ball-shaped valve body 26 rotatably housed within the chamber 25. It is usually located at the lower part of the vehicle body in the direction of inclination. The upper part of the chamber 25 that accommodates the valve element 26 in the inclination direction communicates with the chamber 8 on the left side of the proportion valve 1 via the valve mechanism 27 and the passage 28, and the lower part of the chamber 25 in the inclination direction communicates with the valve mechanism 27 and the passage 28. body 2
Valve seat 29 and passage 30 where 6 is seated due to its own weight
It communicates with a chamber 31 formed on the left end side of the piston 21 through the piston 21 .

As shown in an enlarged view in FIG. 2, the valve mechanism 27 includes a disk-shaped plate body 33 having a through hole 32 formed approximately in the central axis thereof, and a passageway surrounding the plate body 33. The through hole 32 is closed on the 28 side by its own elasticity.
The valve body 35 includes an elastic body 34 made of rubber or the like having a flexible portion 34a that closes the passage 28, and a spring 36 that biases the valve body 35 in one direction to normally close the passage 28. Therefore, this valve mechanism 27
is opened when the brake fluid pressure in the chamber 8 exceeds a predetermined value and introduces the brake fluid pressure into the chamber 25, and when the brake fluid pressure in the chamber 8 decreases thereafter, the brake fluid pressure in the chamber 25 is opened. The pressure fluid introduced into the through hole 3
2 and the flexible portion 34 curved by the pressure.
It is discharged to the chamber 8 side through the gap between a and the plate 33. Note that a valve mechanism having the same function can be constructed by providing two parallel branch passages in the middle of the passages 28 and 30, and providing each branch passage with a check valve that allows flow in opposite directions. Can be done. Further, in FIG. 2, 37 is a retainer that receives the spring 36, 38 is a hole bored in the shaft of this retainer, 39 is a stop ring that supports the retainer, and further, in FIG. 1, 40 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 17 to chamber 8, passage 14, chamber 10, passage 13, and chamber 15.
It is guided to the output hole 18 through the , 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, as shown at point a in FIG. 3, the relatively low brake fluid pressure causes the deceleration of the vehicle to exceed a predetermined value.
due to inertia, rolls toward the left in FIG. 1 and leaves the valve seat 29. When the brake fluid pressure increases in this state and reaches the fluid pressure shown at point b in Figure 3, the pressure fluid pushes open the valve body 35 of the valve mechanism 27 and flows into the chamber 25 from the passage 28, and then It flows into the chamber 31 through the gap between the valve body 26 and the valve seat 29 and the passage 30. Then, the pressure fluid flowing into the chamber 31 moves the piston 21 to the right end against the elastic force of the spring 23, reducing the amount of lift of the valve body 11 of the proportion valve 1 as described above.

Then, when the brake fluid pressure increases further and becomes the fluid pressure shown in FIG. The force becomes larger than the energizing force, and the plunger 6 is moved to the left, and the valve body 11 is seated on the valve seat 16, whereby the passage 1
The increase in the brake fluid pressure introduced into the rear wheel cylinder via 3 is stopped. At this time,
As mentioned above, since the amount of lift of the valve body 11 relative to the valve seat 16 is small, the valve body 11 is seated on the valve seat 16 when the plunger 6 moves slightly to the left. point) is smaller than that in the case of loading vehicles, which will be described later.

After this, when the brake fluid pressure further increases, the leftward biasing force acting on the right end surface of the plunger 6 does not increase due to the seating of the valve body 11, but the plunger pressure due to the brake fluid pressure introduced into the chamber 8 does not increase. Since the biasing force of the plunger 6 to the right is increased, the plunger 6 moves to the right and displaces the valve body 12 from the valve seat 14. Then, when the valve body 11 is separated from the valve seat 16, the brake fluid pressure acting on the rear wheel cylinder, that is, the right end surface of the plunger 6 increases, and the plunger 6 is moved to the left and the valve body 11
is seated on the valve seat 16. In this way, the plunger 6 reciprocates left and right as the brake fluid pressure increases, and changes the brake fluid pressure P OUT introduced into the rear wheel cylinder according to the pressure receiving area difference from 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 35 of the valve mechanism 27 (point b in Fig. 3). However, the valve body 26 continues to be seated on the valve seat 29 due to its own weight. Then, in this state, the valve body 35 is pushed open, and the brake fluid pressure is applied to the chamber 2.
5, this pressure fluid presses and holds the valve element 26 against the valve seat 29 due to the pressure difference between the pressure in the chamber 25 and the pressure in the passage 30 and the chamber 31, so that the brake fluid pressure increases thereafter. Even if the deceleration of the vehicle exceeds a predetermined value, the valve body 26 will not separate from the valve seat 29. In this state, no brake fluid pressure is introduced into the above-mentioned chamber 31, so the piston 2
1 and rod 22 continue to be held at the non-operating position shown, and therefore the lift amount L of the valve body 11 is maintained at its maximum value.

In this state, even if the brake fluid pressure reaches point c in FIG. 3 and the plunger 6 is moved slightly to the left, the valve body 1
1 never seats on the valve seat 16, so the output hydraulic pressure P _OUT remains substantially the same as the input hydraulic pressure P _IN . Then, as the brake fluid pressure further increases, the plunger 6 moves significantly to the left and the valve body 11 seats on the valve seat 16 (point d in Fig. 3). After this, the plunger 6 moves left and right as in the case when the vehicle is empty. The output hydraulic pressure increases at a low rate of increase as the input hydraulic pressure increases (see straight line C in FIG. 3). Or at this time,
Distal face of plunger 6 and chamber 8 in non-actuated state
If the distance l' from the wall surface is set slightly smaller than the maximum lift amount L mentioned above, the valve body 11 will not be able to sit on the valve seat 16, and the braking characteristics shown by straight line A' in FIG. 3 will be obtained. It will be done.

FIG. 4 shows an embodiment using a hydraulic pressure sensing valve having another configuration. In this embodiment, the valve mechanism 27 is omitted, and instead a piston 42 is installed in a hole 41 communicating with the passage 30. A rod 43 is attached to the piston 42 to push up the valve body 26, and a spring 45 is loaded between the piston 42 and a plug 44 that closes the hole.
Normally, the valve body 26 is moved to the valve seat 29 by the rod 43.
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, as soon as this occurs, the brake fluid pressure is transferred to the chamber 25 and the passage 3 via the passage 28.
0 and the aforementioned chamber 25, and the brake fluid pressure acts on the left end surfaces of the piston 42 and the piston 21 to try to move them to the right. Therefore, when the vehicle is empty, if the setting is made so that a predetermined deceleration is obtained before the piston 42 moves to the right and the valve body 26 seats on the valve seat 29, the valve body 26 will be seated on the valve seat 29. Since the piston 42 is already rolling to the left due to inertia, the valve body 26 will not be seated on the valve seat 29 even if the piston 42 then moves far to the right. It is possible to introduce sufficient brake fluid pressure to cause the vehicle to move, and braking characteristics when the vehicle is empty can be obtained in the same manner as in the above-described embodiment.

On the other hand, when a vehicle is loaded, before the valve body 26 rolls to the left due to inertia, the piston 42 moves to the right due to brake fluid pressure, and the valve body 26 moves toward the valve seat 29.
Since the piston 26 is seated under its own weight and the valve body 26 is held pressed against the valve seat 29 by the subsequent rise in brake fluid pressure, it is possible to introduce into the chamber 31 enough brake fluid pressure to move the piston 21 to the right. However, braking characteristics during loading can be obtained in the same manner as in the above-described embodiment.

As described above, the present invention is configured to control the advance/retreat position of the rod by the advance/retreat control means according to the loaded state of the vehicle, thereby changing the lift amount of the valve body of the proportion valve. The advance/retreat control means needs only to obtain an acting force that can counteract not the auxiliary force of the proportion valve but the auxiliary force of the valve body, which is much smaller than this auxiliary force. Small compared to those designed to change the
The effect of reducing weight can be obtained.

[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, 7, 12,
23: Spring, 11: Valve body, 16: Valve seat, 17: Input hole, 18: Output hole, 21: Piston, 22: Rod, L: Lift amount.

Claims (1)

[Claims] 1 Contains a valve body that opens and closes the flow path that communicates the input hole and the output hole, and when the valve body is held in the non-operating position, the valve body is pushed up by a rod and removed from the valve seat, and the brake fluid pressure is In the braking hydraulic pressure control device, the braking hydraulic pressure control device is equipped with a proportion valve that operates when the hydraulic pressure exceeds a predetermined value to control the opening and closing of the valve body to increase the output hydraulic pressure at a low rate of increase with respect to the increase in the input hydraulic pressure. The rod is provided to be movable forward and backward, and a piston formed at the other end of the rod is elastically biased in the upward thrust direction, and brake fluid pressure is introduced into the chamber surrounding the step connecting the rod to the piston. A valve mechanism is provided in the introduction passage to open and close the passage when the vehicle is empty and to close it when the vehicle is loaded, depending on the loaded state of the vehicle, and the rod is moved forward and backward by the hydraulic pressure introduced into the chamber to close the valve seat of the valve body. A brake fluid pressure control device characterized by changing the lift amount relative to the brake fluid pressure.