JPS59202964A - Brake fluid pressure control mechanism - Google Patents

Abstract

PURPOSE:To resolve an erroneous operation of a load sensing valve by disposing a wheel loading detection means in series with a resilient member supporting a vehicle so that the wheel loading may be directly detected irrespective of a permanent set in the vehicle suspension resilient member. CONSTITUTION:An oil pressure chamber 26 is a wheel loading detection means and at the same time generates an oil pressure as an actuating signal in response to the wheel loading, and is disposed in series with a resilient member 27 supporting a vehicle between an upper spring member 28 and a lower spring member 29. The oil pressure chamber 26 is formed by a cylinder member 26a and piston members 26b, 26b', and the resilient member 27 is a supension comprising a shock absorber 27a and a coil spring 27b. Since the oil pressure chamber 26 is disposed in series with the resilient member 27 for supporting the vehicle, the wheel loading is determined by the pressure from the oil pressure chamber 26 and is not affected by a bending in the resilient member 27 due to a deterioration by usage.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a brake fluid pressure control mechanism for a vehicle, and particularly to a brake fluid pressure control mechanism that prevents rear wheels from locking during braking.

(Prior Art) When an automobile brakes, a phenomenon occurs in which the center of gravity moves forward according to the speed of deceleration, the front wheel load increases, and the rear wheel load conversely decreases.

Therefore, if proportional braking forces are applied to both the front and rear wheels, only the rear wheels will lock first, resulting in loss of directionality, reduced braking performance, and unstable steering.

(Diagram A in Figure 1) Therefore, a proportioning valve (hereinafter referred to as P pulp) was developed to prevent the rear wheels from locking early. In order to create a shape similar to Figure B), when the master cylinder hydraulic pressure reaches a certain value, the differential pressure piston principle is used to reduce the rate of increase in brake hydraulic pressure only for the rear wheels, thereby reducing rear wheel friction. This is what we are trying to prevent. (Fig. 1 diagram C) However, as shown in IIJ diagram C, P pulp starts operating when the master cylinder hydraulic pressure reaches a certain value, and the breaking point P (hereinafter referred to as split point Y) Since it is determined by the setting, it is not suitable for vehicles where the vehicle weight changes significantly.In response, a load sensing valve was developed that can detect changes in vehicle weight and make the split point variable. As shown in Fig. 2, the ideal curve changes depending on the live load (diagrams Bl, B2.Bs).
According to this, the split point is changed from P1 to P2 to Ps in order to approximate the ideal curve. (
2nd diagram C□, C2, C8) And, for this load sensing valve, linkage type pulp and G pulp that senses the deceleration of the vehicle by inertial mass are conventionally known. The linkage type load sensing valve is described in Japanese Patent Application Laid-Open No. 132377/1982, and as shown in FIG. and the lower part of the spring @4, the vehicle weight is detected by the displacement of the distance between both members 3 and 4, and the split point variable means of the P bulge 5 is operated.

Therefore, if the vehicle suspension elastic body 2 becomes fatigued due to long-term use, the distance will change, and the vehicle weight detection means 1 arranged in parallel will also malfunction, causing the split point to deviate from the optimal position. Furthermore, even when the vehicle weight is roughly constant, the vehicle suspension elastic body 2 deforms due to deceleration, turning, etc., and the split point shifts.

In addition, 6 in FIG. 3 is a master cylinder, 7 is a front wheel brake cylinder, and 8 is a rear wheel brake cylinder.

In addition, the other G-pulp does not detect the weight of the vehicle;
The problem with the above-mentioned linkage type glued sensing valve is that it takes advantage of the fact that the inertial force applied to an inertial mass (generally a sphere) due to vehicle deceleration changes in proportion to the vehicle weight. However, when using a duo servo brake as a braking device, the servo action is about 6 times that of a normal drum brake, making it unstable at the initial stage of braking, and the inertial mass is affected by sudden braking operations. There was a problem in that the G-pulp malfunctioned and started operating at the initial rise of inertia, causing a shift in the split point.

(Object of the present invention) The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a brake fluid pressure control mechanism equipped with a load sensing valve that does not malfunction. This aims to prevent rear wheels from locking in response to changes in vehicle weight, improve vehicle stability during braking, and shorten braking distance.

(Structure of the present invention) A master cylinder that generates hydraulic pressure in response to brake pedal force, a brake cylinder that operates by the hydraulic pressure generated in the master cylinder, and a master cylinder that is interposed between the master cylinder and the brake cylinder. A brake fluid pressure control mechanism that has a load sensing valve that is equipped with a variable setting means that can vary the turning point at which the rate of increase in hydraulic pressure in the rear wheel brake cylinder changes relative to the rate of increase in hydraulic pressure in the rear wheel brake cylinder. A wheel load detection means for detecting and outputting a wheel load signal is arranged in series with the elastic body that suspends the vehicle, and a driving means for outputting a drive signal for driving the setting variable means in accordance with the wheel load signal is provided. It is something.

(Effects of the present invention) Therefore, in the brake fluid stopping mechanism of the present invention,
Since the wheel load detection means is placed in series with the elastic body that suspends the vehicle, the wheel load can be directly detected regardless of the fatigue of the elastic body that suspends the vehicle, thereby preventing malfunction of the load sensing valve. It has the effect of being able to eliminate the problem.

(Example) In describing an example, an automobile brake fluid pressure control i structure will be explained as an example.

First, to explain the first embodiment shown in FIG. 4 and FIG. It is equipped with a master bag 11'f as a booster.

Reference numeral 12 denotes a front wheel brake cylinder, which is connected to the front wheel side connecting end 9a of the tandem master cylinder 9 through a brake pipe 13, and is operated by the hydraulic pressure generated in the tandem master cylinder 9.

Reference numeral 14 denotes a rear wheel brake cylinder, which is connected to the rear wheel side connection end 9b of the tandem master cylinder 9 via a brake pipe 15, a load sensing pulp 16, and a brake pipe 17.
When the four-domain sensing valve 16 does not operate, the hydraulic pressure emitted by the valve 16 is directly received for DJ operation, and when the load sensing pulp 16 is activated, it operates upon receiving the hydraulic pressure with a reduced liquefaction increase rate.

Reference numeral 16 denotes a load sensing pulp, which is interposed between the tandem master cylinder 9 and the rear brake cylinder 14, so that the rate of increase in hydraulic pressure in the rear brake cylinder 14 changes with respect to the rate of increase in liquefaction in the tandem master cylinder 9. It is provided with a spring 18 for setting an operation start point as a setting variable means that can vary the split point, and further provided with an operating piston and an oil field containment chamber 21 in the pulp body 19 as means for operating the spring 18.

The structure of the load sensing pulp 16 will be explained with reference to FIG. 5. 19 is the pulp body, 18a, 1
8b is a spring for setting the operation start point, and 21 is an operation piston.
is the oil field containment chamber, 22 is the plunger, η is the hydraulic pressure input end from the tandem master cylinder 9, U is the hydraulic pressure output end to the rear wheel brake cylinder 14, and 5 is the drive output from the wheel load detection means Hydraulic pressure is the input terminal of

Next, the transmission is an oil well chamber which is a wheel load detection means and generates oil pressure which is a drive signal in response to a wheel load signal,
Between the sprung member portion and the unsprung Mζ material 29 [This is arranged in series with the elastic body portion that suspends the vehicle. Incidentally, as shown in FIG.
and piston members 26b and 26b', and the elastic body n is a suspension composed of a shock absorber 27a and a fill spring 27b.

(g) is a solenoid valve which is interposed between the 4-P sensing pulp 16 and the hydraulic chamber, and is energized and closed when the wheel travel sensor 31 detects the vertical movement of the wheel. In a region where almost no movement is detected, the valve is opened without being energized, and the flow path of the wheel load detection pressure pipe 32 is opened and closed. In addition, the solenoid valve 30 is equipped with a spring (9) a.
The structure includes a ball 30b pressed against the ball 30b, and a solenoid 30d that presses the ball 30b against the spring force against the ball 30c, and the wheel travel sensor 31 has one side on the vehicle body side and the other side on the suspension side. It is installed and detects the vertical movement of the wheel based on the amount of displacement.
One wheel travel sensor 31 may be used, or two left and right wheel travel sensors 31, 31 may be installed to detect cornering.

Therefore, in the first embodiment, since the hydraulic chamber 26 is arranged in series with the elastic body for suspending the vehicle,
The wheel load G is determined by the pressure in the hydraulic chamber, and the elastic body N
Even if deflection occurs due to durability deterioration, the pressure in the hydraulic chamber increases or decreases in proportion to the increase or decrease in wheel load without applying any color tube, allowing wheel load detection without malfunction. .

Then, the wheel load is detected as pressure in the hydraulic chamber 5, and the sealed oil in the hydraulic chamber becomes a driving medium for the operation start point setting spring 18, which is a means for changing the setting of the split point, and is applied to the ME containment chamber 21 of the load sensing pulp 16. It is possible to change the split point according to the ideal braking force curve that changes depending on the wheel load by moving the actuating piston force and applying a spring force according to the wheel load.The master cylinder hydraulic pressure and the rear wheel brake cylinder 14 hydraulic pressure As a result, the ultimate purpose of the load sensing pulp 16 is to prevent early locking of the rear wheels, improve vehicle stability during braking, and shorten braking distance.

In addition, since the embodiment is equipped with a solenoid valve (equipment) and a wheel travel sensor 31, when the wheels move up and down rapidly, such as when turning or driving on an uneven road, the solenoid valve (equipment) and wheel travel sensor 31 are installed. ) detects vertical movement and closes, so that pressure changes in the oil field chamber are not transmitted to the hydraulic containment chamber 21, and the split point is always determined in a static state.
Malfunctions caused by vertical movement of the wheels can be prevented.

Next, the second embodiment shown in FIG. 6 will be explained. This embodiment is different from the first embodiment in that it uses a load sensing pulp 16 in consideration of the case where a failure such as a fluid leak occurs in the brake system. They are different. In other words, in terms of the structure, the front wheel side connecting end 9a of the tandem master cylinder 9
and the hydraulic pressure input end of the 4-d sensing pulp 16 are connected by a brake pipe 13 a, and the hydraulic pressure from the master cylinder 9 is introduced into one end of the syringe 4, and the hydraulic pressure output end and the front brake wheel 12 are connected to each other by a brake pipe 13 a. and are connected by a brake pipe 13b.

Therefore, if a failure such as fluid leakage occurs in the rear brake system, the load sensing pulp 16 simply acts as a connector and the front brake will operate normally. The split point hydraulic pressure becomes high because the front wheel side hydraulic pressure is not introduced to one end of the plunger n, and the effectiveness of the rear wheel brake is almost the same as when there is no pulp.

Note that the other functions such as the split point changing function of the load sensing barde 16 are the same as in the first embodiment.

Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment. The split point setting variable means may be converted into an electrical signal as a drive signal, and the split point setting variable means may be variably operated by a solenoid or a motor.

Alternatively, a configuration may be adopted in which the detected electric signal from the IIE electric element is converted into oil pressure and the split point is changed using the same load sensing pulp as in the embodiment.

[Brief explanation of the drawing]

Figure 1 is a hydraulic pressure diagram based on P pulp, Figure 2 is a hydraulic pressure diagram based on load sensing pulp, Figure 3 is a schematic diagram showing a conventional brake fluid pressure control mechanism, and Figure 4 is a first embodiment of the present invention. A schematic diagram showing an example brake fluid pressure control mechanism, FIG. 5 is a sectional view showing essential parts of the mechanism of the first embodiment, and FIG. 6 is a brake fluid pressure control device 1ff of the second embodiment of the present invention! FIG. 4 is an overall view showing 4. 9... Tandem master cylinder (master cylinder), 12... Front wheel brake cylinder, 14... Rear wheel brake cylinder, 16..., P sensing valve,
18... Spring for setting the start of operation (variable setting means),... Hydraulic chamber (wheel load detection means, drive means),! ...
Elastic body. Patent issuer: Nissan Motor Co., Ltd. Figure 1 Figure 2 Master series Figure 3

Claims (1)

[Claims] (1) A master cylinder that generates hydraulic pressure in response to brake pedal force, a brake cylinder that operates by the hydraulic pressure generated in the master cylinder, and a brake cylinder that is interposed between the master cylinder and the brake cylinder and that controls the hydraulic pressure of the master cylinder. A brake fluid pressure control mechanism that directly detects the wheel load and includes a low r sensing valve that is equipped with a setting variable means that can vary the turning point at which the fluid pressure increase rate of the rear wheel brake cylinder changes with respect to the increase rate. A wheel load detecting means for outputting a wheel load signal is arranged in series with an elastic body for suspending a military vehicle, and a driving means is provided for outputting a drive signal for driving the setting variable means in accordance with the wheel load signal. A brake fluid pressure control mechanism featuring: