JPS6167652A - Brake liquid pressure controller - Google Patents

Abstract

PURPOSE:To approach the braking force distribution to an ideal one at any time by providing a section for regulating the liquid pressure to be produced from proportioning valve section with predetermined ratio and varying the braking force distribution from initial stage of braking between loading and empty times. CONSTITUTION:In a liquid pressure regulator 10 to be placed in a conduit 7 for coupling the delivery port 4 of master cylinder 1 with the wheel cylinder 8 of rear wheel, a proportioning valve 17, a reducing valve 18 and a changeover valve 19 are provided respecively at first to third bores 14-16 formed approximately in parallel in the body 10. The changeover valve 19 has a valve body 45 to be opened/closed by a changeover unit 50 for producing the operating force on the basis of the displacement of rear axle AX variable with the weight of car through rod section 46. Under closure of valve body 45, pressure liquid is fed from said valve 17 through the reducing valve 18 into the output chamber 13 while under opening of valve body 45, said pressure liquid is fed into the output chamber 13 while detouring the reducing valve 18.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a brake fluid pressure control device, and more particularly to a brake fluid pressure control device used in a vehicle brake system.

(Prior Art) The brake fluid pressure control device described above brings the balance of the front and rear wheel brakes close to the ideal, that is, close to the ideal braking force distribution.8. In order to prevent the rear wheels from locking up, the system changes the ratio of the front wheel control force to the rear wheel control force by controlling the hydraulic pressure supplied from the master cylinder to the rear wheel brakes. The one disclosed in No. 89467/1983 is known. In addition, the above ideal braking force distribution is
It changes depending on whether the vehicle is loaded or unloaded, that is, the weight of the vehicle.For this reason, even in the brake fluid pressure control device disclosed in the above-mentioned published utility model publication, the vehicle Lfft when loaded, that is, the vehicle Lfft, varies depending on the vehicle weight. Sometimes, the braking force on the rear wheels is increased to approximate the ideal braking force distribution when the vehicle is loaded.

(Problem to be Solved by the Invention) However, in the brake fluid pressure control device described in the above-mentioned published utility model gazette, etc., the operation start point, that is, the split point, is simply changed depending on the vehicle weight using a spring. Therefore, in the early stages of braking, the power loss is large, and the distribution of braking force is relatively far away from the ideal braking force distribution, which increases the burden on the front wheel brakes, and as a result, the front wheel lining wears out quickly. It has the disadvantage of becoming.

SUMMARY OF THE INVENTION An object of the present invention is therefore to provide a brake fluid pressure control device that can obtain a braking force distribution close to the ideal braking force distribution even when a vehicle is loaded.

(Means for Solving the Problems) The present invention provides brake fluid pressure that changes the ratio of front wheel braking force to rear wheel braking force by controlling the hydraulic pressure supplied from the master cylinder to the rear wheel brake. The control device has a proportioning valve whose input chamber is connected to the master/cylinder, and a proportioning valve that receives the hydraulic pressure generated by the proportioning valve section, regulates this hydraulic pressure at a predetermined ratio, and discharges it. a pressure section, a switching section that switches the operation of the pressure regulation section according to the vehicle weight, a first pressure fluid passage that supplies pressure fluid from the pressure regulation section, and a first pressure fluid passage that supplies the pressure fluid pressure regulated by the pressure regulation section to the The present invention is characterized in that it includes a second pressure fluid passageway that supplies fluid to the proportioning section to change the characteristics of the proportioning valve. The pressure regulating section may be configured with a pressure reducing valve, and the switching section operates the pressure regulating section when the vehicle weight is relatively small, and operates the pressure regulating section when the vehicle weight is relatively large. It is possible to use one configured to operate so as to deactivate the section.

(Function) In the brake fluid pressure control device of the present invention having the above configuration, by using the above-mentioned pressure regulating section, the braking force distribution is changed from the initial stage of braking when the vehicle is loaded and when the vehicle is empty. The pressure fluid whose pressure is regulated by the pressure regulating section is supplied to the proportioning valve through the second pressure fluid passage, thereby changing the split point pressure of the proportioning valve, thereby reducing the braking force. The distribution can always be kept close to the ideal braking force distribution.

(Embodiment) Hereinafter, a brake fluid pressure braking device according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

First Embodiment FIG. 1 is a sectional view showing a brake fluid pressure control device according to a first embodiment of the present invention. In FIG. 1, reference numeral 1 indicates a master cylinder, and this mask cylinder discharges brake pressure fluid of the same pressure from its discharge port 3.4 in response to the depression force on the brake pedal 2. One of the discharge ports 3 is communicated with a wheel cylinder 6 of the front wheel via a conduit 5, and this wheel cylinder 6 receives the brake pressure fluid discharged from the master cylinder as it is. The other discharge port 4 communicates with a wheel cylinder 8 of the rear wheel via a pipe 7, and a hydraulic pressure adjustment device 10 is interposed in this pipe 7.

This hydraulic pressure adjustment device 10 includes a device main body 11.

This device main body 11 has manpower rooms 1 on the left and right in the figure.
2 and an output chamber 13 are formed. This device body 1
1 is also formed with first, second, and third bores 14, I5, and 16, which are arranged substantially in parallel from the manpower room 12 side. A proportioning valve 17 is provided in the first bore I4, a pressure reducing valve 18 is provided in the second bore 15, and a third
A switching valve 19 is provided in each bore 16 . Note that the first and third bores 14 and 16 are bored from below the main body 11 in the figure, while the second bore 1
5 is bored through the main body 11 from above.

The lower opening of the first bore 14 is closed with a plug 20, and the space surrounded by the main body II and the plug 20 functions as the seventh cylinder 21 of the blotting hull 17. A plunger 22 is fitted into the cylinder 21 so as to be slidable in the vertical direction within the cylinder 21. Near the bottom of this plunger 22,
A piston 23 is provided, and an enlarged diameter portion 2 is provided above the piston 23.
4 are provided. A spring 25 is disposed in a chamber above the enlarged diameter portion 24 of the cylinder 21, and the plunger 22 is biased downward by the spring 25. The space within the cylinder 21 communicates with the input chamber 12 through a passage 26 .

Pressure fluid from the master/cylinder 1 acts on the lower surface 23a of the piston 23 even when the plunger 22 is at the lowest position, so that the cylinder 21
When brake pressure fluid with a pressure higher than a predetermined pressure is introduced into the spring 25, the plunger 22 is pushed upward against the spring 25.
The piston 23 and the enlarged diameter portion 24 when the is at the lowest position
The position on the inner surface of the cylinder 21 corresponding to the position between
The seat 27 is fixed, and the piston 23 comes into contact with the seat 26 when it moves upward a predetermined distance. When the piston 23 comes into contact with this seat 27, it cuts off communication between the upper and lower chambers of the cylinder 21. This point in time is called the split point. Even after this split point, the piston 23 of the cylinder 21
Brake pressure fluid continues to be supplied from the master cylinder 1 to the upper chamber, so the pressure in this upper chamber becomes high.
The piston 23 and therefore the plunger 22 are pushed downward,
Brake pressure fluid is again supplied to the lower chamber of the piston 23, and the state before the split point is about to be achieved. While repeating these two states, the discharge hydraulic pressure of the proportioning valve 17 increases at a lower rate of increase than the hydraulic pressure from the mask cylinder 1. The discharge pressure liquid of the provisioning hull 17 is supplied to the second bore 15 through a passage 28. The upper end of the plunger 22 is fitted into a guide hole 11a provided in the main body (1) to guide vertical sliding movement of the plunger.

The upper opening of the second bore 15 is closed with a plaque 30, and the space surrounded by the main body 11 and the plug 30 functions as a cylinder 31 of the pressure reducing valve 18. This cylinder 31 has a lower portion reduced in diameter to form a shoulder portion 32 for the purpose to be explained later. A decompression piston 33 that extends above and below the shoulder portion 32 is fitted into the cylinder 31 so as to be slidable in the vertical direction.

This pressure reducing piston 33 is also formed with a shoulder gB34, and this shoulder 81S34 comes into contact with the shoulder portion 32, thereby preventing the piston 33 from sliding any further downward. A through hole 35 is formed in the center of the piston 33 and extends in the vertical direction.
5, the upper and lower chambers 3 of the piston 33 in the cylinder 31
1a and 31b are communicated with each other.

The piston 33 is located in the center of the lower surface of the plug 30.
A rod-shaped stopper 36 having a diameter smaller than that of the through hole 35 is provided, and this stopper 36 is connected to the top surface of the piston 33 when the piston 33 is at the lowest position as shown in the figure. The piston 30 extends within the through hole 35 to a position with a smaller distance between the lower surface of the piston and the lower surface of the piston. Therefore, the lower end of this stopper 36 does not protrude from the lower surface of the piston 33.

A steel ball 37 for closing the lower opening of the through hole 35 of the piston 33 is arranged in the lower chamber 31b of the cylinder 31. A spring 38 is disposed below this ball 37, and the ball 37 is urged upward by this spring 38, and when the piston 33 is at its lowest position, the lower opening of the through hole 35 is opened. 5), thereby cutting off communication between the upper chamber 31a and the lower chamber 31b.

In the pressure reducing valve 18 having the above structure, when pressure liquid is introduced into the lower chamber 31b, this pressure liquid gradually pushes up the pressure reduction piston 33, but at the same time, the ball 37 also pushes up against the spring 33.
8, the ball 37 closes the opening of the through hole 35 until it comes into contact with the stopper 36. However, when the pressure fluid in the lower chamber 31b further rises and pushes the piston 33 further up, and the lower end of the piston 33 exceeds the lower end of the stopper 36, the movement of the ball 37 is stopped by the stopper 36. Even after this, the piston 33 rises independently, so the opening of the through hole 35 is opened, and the upper chamber 31a of the cylinder 31 is communicated with the lower chamber 32b via the through hole 35. Then, the lower chamber 31b flows from the propioning valve 17 through the passage 28.
The pressure liquid that had been introduced into the upper chamber 31a is now introduced into the upper chamber 31a through the through hole 35. The pressure liquid introduced into the upper chamber 31a acts on the upper surface of the pressure reducing piston 33, and since the area of this upper surface is wider than the lower surface, this piston 33 moves downward. When the piston 33 moves downward in this manner, the opening of the through hole 35 of the piston 33 is closed again by the ball 37 that remained at the lower end of the spacer 36. By repeating the above, the pressure reducing valve 18 further reduces the pressure of the pressure liquid sent from the proportioning valve 17 and discharges it. This discharged pressure fluid is sent to the output chamber 13 through the passage 40, and from there is supplied to the wheel cylinder 8 on the rear wheel side through the conduit 7.

The lower opening of the third bore 16 is closed with a plug 41, and the switching valve 19 is disposed in a space 42 surrounded by the main body 11 and the plug 41. The space 42 is
It communicates with the lower chamber 31b of the cylinder 31 through a passage 43, and with the passage 40 through a passage 44. In the space 42, a valve body 4 having a diameter smaller than that of the space is provided.
5 are arranged so as to be movable in the vertical direction. This valve body 45 is for opening or closing the passage 44 as necessary, and when this passage 44 is closed, the pressure fluid from the propioning valve 17 is released by the action of the pressure reducing valve 18. the output chamber 13 in a depressurized state.
On the other hand, when the passage 44 is open, the pressure fluid from the propioning valve 17 simply passes through the lower chamber 31b of the cylinder 31, that is, the pressure reducing valve 1
8 and is supplied to the output chamber 13 via the space 42, the passage 44, and the passage 40. Note that this valve body 45 is urged upward by a spring 45a, so that the passage 44 is normally closed.

A rod member 46 is attached to the center portion of the lower surface of the valve body 45, and this rod member 46 is connected to the plug 41.
extends downward through the A switching device 50 is attached to the lower end of the rod member 46. The switching device 50 opens and closes the passage 44 by moving the valve body 45 up and down by moving the rod member 46 up and down.

This switching device 50 operates the rod member 46 based on the displacement of the suspension suspension, which changes depending on the weight of the vehicle, and detects the displacement of the rear axle AX and extracts this as the operating force of the rod 46.
51, and an operating section 52 that operates the rod member 46 with a predetermined play based on the operating force of the displacement detection section 51.
and a transmission section 53 that transmits the operating force of the displacement detection section 51 to the actuation section 52.

The actuating section 52 has a cylindrical member 54, and the upper end '11D4a of the cylindrical member 54 is connected to a nut 47 attached to the lower end of the rod 46 (which is pressed down in conjunction with the nut 47). In the non-operating state, there is a gap a between this upper end ``J54a'' and the nut 47, so that the rod is closed only when the displacement or rise of the rear axle △X exceeds a predetermined value. Member 46
I'm trying to move it. This is rear axle A
This is to prevent opening and closing of the passage 44 due to a minute displacement of X.

In order to convert the displacement of the rear axle AX into a driving force for the operating section 52, the displacement detecting section 51 has a lever 55 attached to the vehicle body. This lever 55 has an L-shape and is pivotally mounted at its base by a pin 56. This lever 55 also has its horizontal component 55a
is connected to a bracket 57 mounted on the rear axle AX by a cable 58, and a spring 59 is interposed between the horizontal portion 55a and the bracket 57. With this structure, the rear axle AX The upper part of the lever 55 is transmitted to a lever 55, so that the lever 55 rotates around a pin 56. In order to transmit this rotation of the lever 55 to the actuating part 52,
The transmission section 53 carries a cable 60 that connects the lower end of the vertical portion 55b of the lever 55 and the cylindrical member 54 of the actuating section 52.A spring 61 is provided in the middle of this cable 60. The sudden force of power (
Avoiding communication.

A split point control pressure liquid chamber 70 is formed above the plunger 22 of the propioning valve 17 of the main body 11, and this pressure liquid chamber 70 is connected to the plug 30.
It communicates with the upper chamber 31a of the cylinder 31 of the pressure reducing valve 18 through an annular chamber 71 and a passage 72 formed by reducing the diameter of the lower part of the passage 40 and the annular chamber 7.
1. It communicates with the passage 44 via the passage 72.

Therefore, when the car is empty, a relatively low pressure liquid is introduced into the pressure liquid chamber 70, which is affected by the pressure reducing valve 18, and when the car is loaded, a relatively high pressure liquid which is not affected by the pressure reducing valve 18 is introduced into the pressure liquid chamber 70. liquid is introduced. Piston 23 of plunger 22
The pressure of the pressurized liquid acting on the lower surface of the pressurized liquid is against the pressure of the pressurized liquid introduced into the pressure liquid chamber 70, that is, it acts in the opposite direction. (split point when the vehicle is empty) Compared to B, the front wheel hydraulic pressure will shift to the higher pressure side. In summary, with the brake fluid pressure control device according to the first embodiment described above, it is possible to obtain front and rear wheel braking force distribution characteristics when the vehicle is empty and when the vehicle is loaded, as shown by the broken line in FIG. .

Second Embodiment In this second embodiment, the pressure fluid supplied to the proportioning valve 17 with or without the pressure reducing valve 18 and controlling the split point of this proportioning valve 17 is as described above. Unlike the first embodiment, the pressure fluid is configured to act in the same direction as the pressure fluid acting on the piston 23, that is, in the forward direction.

Therefore, in this second embodiment, as shown in FIG.
The front wheel hydraulic pressure is shifted to the lower pressure side compared to the split point when the vehicle is empty. For this reason, in this embodiment, the piston 23 is disposed relatively above the plunger 22 as shown in FIG.
The direction in which the pressure fluid acts on the surface 23a of the piston 23 is reversed from that in the first embodiment, and is configured to be the same as the direction in which the pressure fluid in the pressure fluid chamber 70 acts on the plunger 22. . Note that due to this change, there are also some changes in other parts, but since these are slight changes, explanations will be omitted.

(Effects) As explained above, in the brake fluid pressure control device according to the present invention, when the vehicle is empty, it is a pressure reducing valve. J
Since the pressure regulator 11 operates, and the pressure regulator does not operate during loading, it is possible to improve the effectiveness of the brake, especially at the initial stage of braking during loading. In addition, the split point of the proportioning hub is controlled by applying the pressure fluid, which may or may not be affected by the pressure regulating section, to the proportioning hub, so it is possible to distribute the braking force between the front and rear wheels. Therefore, it is possible to set the braking force distribution close to the ideal braking force distribution for the vehicle.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a brake fluid pressure control device according to a first embodiment of the present invention, FIG. 2 is a graph showing front and rear wheel braking characteristics by the control device shown in FIG. 1, and FIG. 4 is a diagram showing a brake fluid pressure control device according to a second embodiment of the present invention, and FIG. 4 is a graph showing front and rear wheel braking characteristics by the control device shown in FIG. 1 Master cylinder, 6 Front wheel cylinder, 8
Rear wheel cylinder, lO fluid pressure adjustment device, 12
Manpower room, 13 Output room, 17 Proportioning valve, 18 Pressure reducing valve, 19 Switching valve, 50 Switching device, 5
1 Displacement detection section, 52 Actuation section, 53 Transmission section, 70
Pressure fluid chamber, 71 Annular chamber, 72iITl tract.

Claims (2)

[Claims] (1) A brake fluid pressure control device that changes the ratio of front wheel braking force to rear wheel braking force by controlling the hydraulic pressure supplied from a master cylinder to the rear wheel brake,
a proportioning valve section having an input chamber connected to the master cylinder; a pressure regulating section that receives the hydraulic pressure generated by the proportioning valve section, regulates this hydraulic pressure at a predetermined ratio and discharges it; and the pressure regulating section. a switching section that switches the operation according to the weight of the vehicle; a first pressure fluid passage that supplies pressure fluid from the pressure regulation section; and a first pressure fluid passage that supplies the pressure fluid pressure-regulated by the pressure regulation section to the proportioning section; A brake fluid pressure control device including a second pressure fluid passage that changes the characteristics of a proportioning valve. (2) The pressure regulating section is composed of a pressure reducing valve, and the switching section operates the pressure regulating section when the vehicle weight is relatively small, and operates the pressure regulating section when the vehicle weight is relatively large. 2. The brake fluid pressure control device according to claim 1, wherein the brake fluid pressure control device is configured to put the brake fluid pressure in an inoperative state.