JPH08133052A - Reservior for brake hydraulic pressure control device - Google Patents

Abstract

PURPOSE: To simplify control logic at the time of pressure reduction by making brake hydraulic pressure in a reservior nearly constant regardless of the position of a piston in the sliding direction. CONSTITUTION: A reservior 40 comprises a cylinder 40A and a piston 42 which is slidably inserted into the cylinder 40A with fluid tight. The cylinder 40A is installed so that the sliding direction of the piston 42 becomes a vertical direction. The pressure of a brake liquid in the position of the opening part 40B of the cylinder 40A is one in which the pressure based on the self-weight of the brake liquid in the cylinder 40A is added to the pressure based on the self-weight of the piston 42. However, since the pressure based on the self-weight of the brake liquid is sufficiently small as compared with the pressure based on the self-weight of the piston 42, it can be neglected. As a result, brake hydraulic pressure can be made nearly constant regardless of the position of the piston 42, and control logic used for computation at the time of pressure reduction is simplified.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake fluid pressure control device reservoir, and more particularly to a brake fluid pressure control device for controlling the pressure of the brake fluid in a wheel cylinder for temporarily storing the brake fluid. Regarding the reservoir.

[0002]

2. Description of the Related Art With the recent high performance of automobiles, it is necessary to secure stable braking performance and to stop the vehicle with sufficient braking force and stability. An anti-lock brake system (ABS) that prevents the wheels from falling into a locked state when the vehicle is suddenly braked on a slippery road surface because the wheels are locked and the running stability of the vehicle is reduced. Is proposed. In ABS, the frictional force between the wheel and the road surface is maximized when the ratio of the difference between the vehicle body speed and the wheel speed (slip ratio) is a predetermined value, and the maximum braking force is obtained at the maximum point of the frictional force. And the force (cornering force) generated by steering during running to keep the traveling direction of the vehicle is the maximum when the slip ratio is 0% and the value is 0 when the slip ratio is 100% (locked state). Since the vehicle is likely to spin when the cornering force is small, the brake fluid pressure of each wheel is controlled so that the braking force due to the frictional force and the steerability due to the cornering force are both within a slip ratio range.

Contrary to braking, when starting on a slippery road surface or when suddenly accelerating, the drive wheel spins and the driving force cannot be utilized, and the stability of the vehicle body deteriorates. Traction control (TR) that suppresses excessive slip of the vehicle and secures directional stability and driving force of the vehicle
C) is proposed. In the TRC as well as in the ABS, the relationship between the friction force and the slip ratio (the ratio of the difference between the driving wheel speed and the vehicle body speed with respect to the driving wheel speed) and the relationship between the cornering force and the slip ratio are established. The torque of the engine is controlled and the pressure of the brake fluid of the driving wheels is controlled so that the steering ratio by the cornering force and the steering property are within the range of the slip ratio.

In the pressure control of the brake fluid, pressurization is
In ABS, the brake pedal is depressed, and in TRC, a pressurizing device is used to pressurize and inject the brake fluid into the wheel cylinders. The brake fluid pressure is reduced by draining the brake fluid from the wheel cylinder.

Such a device for controlling the brake fluid pressure generally includes a reservoir for temporarily storing the brake fluid extracted from the wheel cylinder when the brake fluid pressure is reduced. Conventionally, as a reservoir for a brake fluid pressure control device of this type, a reservoir that uses a spring to exert a pressure on the brake fluid has been proposed (for example, Japanese Patent Laid-Open No. Hei 4).
No. 231248). This reservoir is composed of a cylinder, a piston slidably fitted in the cylinder, and a spring for urging the piston in a direction to pressurize the brake fluid in the cylinder. The reason why the piston is biased by the spring to apply the pressure to the brake fluid is mainly to push the brake fluid temporarily stored in the reservoir into the pump for returning it to the brake master cylinder.

[0006]

However, in such a reservoir for a brake fluid pressure control device that biases a piston with a spring, the biasing force of the spring changes depending on the position in the sliding direction of the piston, and the brake fluid in the reservoir is changed. There is a problem that the control logic at the time of decompression becomes complicated because the acting pressure changes. The brake fluid pressure is reduced by opening an opening / closing valve installed in a pipe connecting the wheel cylinder and the reservoir for a predetermined time to drain the brake fluid from the wheel cylinder. The amount of brake fluid extracted is determined by the difference between the pressure in the wheel cylinder and the pressure in the reservoir and the opening time of the on-off valve.Therefore, if the pressure acting on the brake fluid changes depending on the piston position, the brake fluid in the wheel cylinder will be changed. Even if the hydraulic pressure and the opening time of the opening / closing valve are the same, the amount of the brake fluid extracted is different, and the depressurizing amount of the brake fluid is different. Therefore, in the control when reducing the brake fluid pressure,
In order to make the amount of brake fluid pressure reduction the same regardless of the piston position, not only the brake fluid pressure of the wheel cylinder but also the brake fluid pressure in the piston position or in the reservoir is detected, and based on the detected value, the opening / closing valve The opening time must be determined.

Further, the brake fluid pressure in the wheel cylinder that can be reduced is up to the brake fluid pressure in the reservoir, but since the brake fluid pressure in the reservoir changes depending on the position of the piston, this reducible pressure is also reduced. Change. In order to make the depressurizable pressure constant, it is necessary to make the brake fluid pressure in the reservoir constant, but this makes the position of the piston constant and impairs the function of the reservoir. In order to return to the same pressure in a short time when the depressurizable pressure changes, it is necessary to return the piston to the same position in a short time. For this purpose, it is necessary to increase the transfer capacity of the pump that sends the brake fluid stored in the reservoir to the brake master cylinder side, which increases the size of the device.

The reservoir for the brake fluid pressure control device of the present invention solves such a problem, makes the pressure of the brake fluid in the reservoir substantially constant regardless of the position of the piston in the sliding direction, and provides a control logic for pressure reduction. The following configuration is adopted for the purpose of facilitating.

[0009]

A reservoir for a brake fluid pressure control device according to the present invention is used in a brake fluid pressure control device for controlling the pressure of brake fluid in a wheel cylinder, and is a reservoir for temporarily storing the brake fluid. And a cylinder, a piston that is fluid-tightly and slidably inserted into the cylinder, and a substantially constant pressure is applied to the brake fluid in the cylinder regardless of the position of the piston in the sliding direction. The gist of the present invention is to include a pressurizing means.

In the brake fluid pressure control device reservoir, the cylinder is arranged such that the piston slides in the vertical direction, has an introduction path for introducing the brake fluid from a vertically lower portion, and the pressurizing means is It is also possible to adopt a structure that is a means for applying a substantially constant pressure to the brake fluid by the weight of the piston.

[0011]

In the reservoir for brake fluid pressure control device of the present invention constructed as described above, the pressurizing means causes the brake fluid introduced into the cylinder to have a substantially constant pressure regardless of the position of the piston in the sliding direction. Add. Here, “substantially constant” means that the pressure acting on the brake fluid introduced into the cylinder does not change in accordance with the change in the position of the piston, and that the change is small even if it changes.

In the reservoir for the brake fluid pressure control device according to the second aspect, the piston applies substantially constant pressure to the brake fluid in the cylinder by its own weight.

[0013]

Preferred embodiments of the present invention will be described below in order to further clarify the structure and operation of the present invention described above. FIG. 1 is a block diagram illustrating an outline of an antilock brake system 10 including a reservoir for a brake fluid pressure control device of the present invention.

As shown in the figure, the anti-lock brake system 10 includes a brake master cylinder 14 for converting a depression force applied to a brake pedal 12 into a pressure acting on a brake fluid, and wheels installed on the wheels 72 to 78. AB for adjusting the brake fluid pressure to the cylinders 92-98
The S actuator 20, the speed sensors 82 to 88 for detecting the wheel speeds of the wheels 72 to 78, and the ABS computer 10 for controlling the operation of the ABS actuator 20.
With 0 and.

The front chamber of the brake master cylinder 14 is
An ABS actuator 20 is provided in the rear chamber of the brake master cylinder 14 by a pipe 18 serving as a brake fluid delivery pipe for the left front wheel and the right rear wheel system by a pipe 16 serving as a brake fluid delivery pipe for the right front wheel and the left rear wheel system. (See FIG. 2). ABS actuator 20
Each of the wheel cylinders 92 to
It is connected to 98. The pipes 66, 68 connecting the ABS actuator 20 and the hole cylinders 96, 98 of the rear wheels 76, 78 have a proportioning valve 69 for making the pressure of the brake fluid on the wheel cylinders 96, 98 side smaller than that on the brake master cylinder 14 side. Is installed. The proportioning valve is installed only on the pipe on the rear wheel side because the rear wheel is more likely to lock during braking than the front wheel. The ABS actuator 20 and the speed sensors 82 to 88 are connected to the ABS computer 100.

FIG. 2 is a block diagram showing an outline of the antilock brake system 10 centering on the ABS actuator 20. As shown, the ABS actuator 20 includes four holding solenoid valves 22 to 28 for the wheel cylinders 92 to 98 installed on the wheels 72 to 78, and four pressure reducing solenoid valves 3 similarly.
2 to 38 and reservoirs 40 and 5 for temporarily storing brake fluid for the right front wheel and the left rear wheel system, the left front wheel and the right rear wheel system
0, and pumps 47 and 57 for pumping the brake fluid stored in the reservoirs 40 and 50 to the pipes 16 and 18 on the brake master cylinder 14 side.

The holding solenoid valves 22 to 28 are connected to the brake master cylinder 14 by pipes 16 and 18, respectively. Also, each holding solenoid valve 22-2
8 is a wheel cylinder 92-through pipes 62-68.
It is connected to 98. Each pressure reducing solenoid valve 32 ~
38 is connected to the wheel cylinders 92 to 98 by the branch pipes 62A to 68A of the pipes 62 to 68 and the pipes 62 to 68. In addition, each pressure reducing solenoid valve 32 to
38 is a branch pipe 43A, 43 of the connecting pipes 43, 53
B, 53A, 53B and connecting pipes 43, 53 are connected to the reservoirs 40, 50. Communication pipe 43,
53 is the pipes 16 and 18 by the return pipes 44 and 54.
It is connected to the. The return pipes 44, 54 have check valves 46, 56 for allowing the flow of the brake fluid only from the connecting pipes 43, 53 side to the pipes 16, 18 side.
And pumps 47 and 57 for pumping brake fluid from the reservoirs 40 and 50 to the pipes 16 and 18, and the check valve 4.
Pipe 1 from the connecting pipes 43 and 53 side as well as 6, 56
Check valves 48 and 58 which allow the flow of the brake fluid only on the 6 and 18 sides are connected in series. The holding solenoid valves 22 to 28, the pressure reducing solenoid valves 32 to 38, and the pumps 47 and 57 are connected to the ABS computer 100.

FIG. 3 is an explanatory view showing a state where the holding solenoid valve 22 is off, and FIG. 4 is a holding solenoid valve 22.
It is explanatory drawing which shows the state at the time of ON of. The holding solenoid valve 22 is an on-off valve interposed between the pipe 16 and the pipe 62, and as shown in FIGS. 3 and 4, the plunger 22 that opens and closes the port 22E to the pipe 16.
A, a spring 22B for urging the plunger 22A in the opening direction, and a coil 22C formed with the plunger 22A as a core with the opening / closing direction of the plunger 22A as an axis.
Irrespective of the position of the plunger 22A, when the brake fluid pressure on the pipe 62 side is greater than the pipe 16 side, the pipe 6
And a check valve 22D for introducing the brake fluid on the second side to the pipe 16 side. Also, pipe 1 of port 22E
An orifice 22F for adjusting the flow rate of the brake fluid in the port 22E is formed on the 6 side. The holding solenoid valve 22 is connected to the ABS computer 100 (see FIG. 2) and turns on / off the power supply to the coil 22C based on a drive signal from the ABS computer 100.

The holding solenoid valve 22 includes a coil 22.
When C is not energized (when it is off), the plunger 22A is urged by the spring 22B to the side opposite to the port 22E, and the port 22E is opened, as shown in FIG. When the brake pedal 12 is depressed in this state, the brake fluid in the brake master cylinder 14 is guided to the wheel cylinder 92 through the path of the pipe 16, the holding solenoid valve 22, the pipe 62, and the wheel cylinder 92, and the brake fluid in the brake master cylinder 14 is reached. The pressure is transmitted to the wheel cylinder 92 as it is. When the coil 22C is energized (when it is on), the holding solenoid valve 22 attracts the plunger 22A to the port 22E side against the spring 22B by electromagnetic induction by the coil 22C, as shown in FIG. The port 22E is closed. In this state, even if the brake pedal 12 is depressed, the brake hydraulic pressure of the brake master cylinder 14 is not transmitted to the wheel cylinder 92. However, when the brake pedal 12 is released and the brake fluid pressure becomes higher on the wheel cylinder 92 side than on the brake master cylinder 14 side, the check valve 22D opens and the brake fluid in the wheel cylinder 92 is reduced. The holding solenoid valves 24 to 28 also have the same structure as the holding solenoid valve 22.

FIG. 5 is an explanatory view showing a state in which the pressure reducing solenoid valve 32 is off, and FIG. 6 is a pressure reducing solenoid valve 32.
It is explanatory drawing which shows the state at the time of ON of. The pressure reducing solenoid valve 32 includes a branch pipe 62A of the pipe 62 and a communication pipe 4
An on-off valve interposed between the branch pipe 43A of 3 and
As shown in FIGS. 5 and 6, the plunger 32A for opening and closing the port 32E to the branch pipe 43A, the spring 32B for urging the plunger 32A in the closing direction, and the plunger 32A for centering the opening and closing direction of the plunger 32A. And a coil 32C formed so that An orifice 32F for adjusting the flow rate of the brake fluid in the port 32E is formed on the branch pipe 43A side of the port 32E. The depressurizing solenoid valve 32 is connected to the ABS computer 100 (see FIG. 2).
The coil 32C based on the signal from the computer 100
Turn on / off the power to the.

The pressure reducing solenoid valve 32 is a coil 32.
When C is not energized (OFF), the plunger 32A is biased toward the port 32E by the spring 32B, and the port 32E is closed, as shown in FIG. When the coil 32C is energized (on),
As shown in FIG. 6, the depressurizing solenoid valve 32 is in a state in which the plunger 32A is attracted to the side opposite to the port 32E against the spring 32B by the electromagnetic induction by the coil 32C, and the port 32E is opened. In this state,
The brake fluid in the wheel cylinder 92 is the pipe 62, the branch pipe 62A, the pressure reducing solenoid valve 32, and the branch pipe 43.
A, the connecting pipe 43, the reservoir 40 through the reservoir 4
The brake fluid in the wheel cylinders 92 is depressurized. The pressure reducing solenoid valves 34 to 38 have the same structure as the pressure reducing solenoid valve 32.

FIG. 7 is an explanatory diagram illustrating the structure of the reservoir 40, and FIG. 8 is an explanatory diagram illustrating the operating state of the reservoir 40. As shown in FIG. 7, the reservoir 40 includes a cylinder 40A having a cylindrical storage space, and a piston 42 that is fluid-tightly and slidably fitted in the cylinder 40A. The cylinder 40A is arranged so that its axis is in the vertical direction. Therefore, the piston 42 slides in the vertical direction. An opening 40B into which the brake fluid can be introduced is formed in the center of the vertical lower surface (lower part in FIG. 7) of the cylinder 40A. The opening 40B is connected to the communication pipe 43. Further, an opening portion 40C capable of introducing the atmosphere is formed in the vertical upper portion of the cylinder 40A, and the piston 4
The vertical upper part of 2 is open to the atmosphere. Piston 42
Is formed of aluminum, and an O-ring 42A is attached to the outer peripheral edge of the circumference.

The reservoir 40 is a pressure reducing solenoid valve 3
When 2 is turned on, the plunger 32A of the pressure reducing solenoid valve 32 is attracted by the coil 32C and the port 3
2E opens and is connected to the wheel cylinder 92 via the pipe 62, the branch pipe 62A, the pressure reducing solenoid valve 32, the branch pipe 43A and the connecting pipe 43 (see FIG. 2).
By this connection, the brake fluid lifts the piston 42 of the reservoir 40 and flows into the cylinder 40A (see FIG. 8). At this time, in the brake fluid in the cylinder 40A,
If the mass of the piston 42 is M, the area of the cross section perpendicular to the sliding direction of the piston 42 is S, and the gravitational acceleration is g, the pressure P1 = Mg / S based on the weight of the piston 42 acts.
In this embodiment, the mass M and the area S of the piston 42 are adjusted so that the pressure P1 is 0.2 MPa.

The pressure P of the brake fluid at the position of the opening 40B is a value obtained by adding the pressure P1 based on the weight of the piston 42 described above to the pressure P2 based on the weight of the brake fluid in the cylinder 40A. Here, if the specific gravity of the brake fluid is γ and the stroke position of the piston 42 is x, the pressure P2 is
The pressure is represented by P2 = γgx. Brake fluid (for example,
The specific gravity γ of DOT3 using glycol ether or DOT4 using boric acid ester of glycol ether is 0.981 to 1.086 g / cm ³ , and the piston 4
Since the stroke of 2 is 3.3 to 4.2 mm,
The pressure P2 based on the own weight of the brake fluid is sufficiently smaller than the pressure P1 based on the own weight of the piston 42, and can be ignored. Therefore, the pressure P of the brake fluid at the position of the opening 40B is the pressure P based on the own weight of the piston 42.
It can be said that it is the same as 1. The reservoir 5
0 also has the same structure as the reservoir 40.

As shown in FIG. 9, the ABS computer 100 is configured as a logical operation circuit centered on a microcomputer, and more specifically, it performs various arithmetic processes for controlling the ABS actuator 20 according to a preset control program. CPU102 and CPU10 which execute
2, a ROM 104 in which control programs and control data necessary for executing various arithmetic processes are stored in advance, and a RAM 106 in which various data necessary for executing various arithmetic processes by the CPU 102 are temporarily read and written. Input interface circuit 10 for inputting detection signals from speed sensors 82-88 installed on wheels 72-78
8, each holding solenoid valve 22 to 28, each pressure reducing solenoid valve 32 to 3 according to the calculation result in the CPU 102
8 and pumps 47, 57 and the like, and an output interface circuit 110 that outputs a drive signal. Further, the ABS computer 100 includes a power supply circuit 112 connected to a battery (not shown) and is configured to supply a necessary voltage to each unit.

ABS computer 1 configured in this way
00, the vehicle speed is estimated based on the detection signals from the speed sensors 82 to 88, the ratio (slip ratio) of the difference between the vehicle speed and the wheel speed to the vehicle speed is calculated, and the slip ratio is within a predetermined range. The holding solenoid valves 22 to 28 and the pressure reducing solenoid valves 32 to 38 of the ABS actuator 20 are opened and closed so that the pressure of the brake fluid in each wheel cylinder 92 to 98 is controlled.

Next, the anti-lock brake system 10
The operation of will be described. The anti-lock brake system 10 has, for example, a wheel acceleration of a predetermined value or less (absolute value of wheel deceleration is a predetermined value or more) when a sudden brake is applied.
The wheel cylinders 92 to 98 are activated when the change in the slip ratio changes by a predetermined value or more so that the braking force due to the frictional force between the wheel and the road surface and the steerability due to the cornering force are both within the slip ratio range. Increase or decrease or maintain the brake fluid pressure of.

FIG. 10 shows an antilock brake system 1
0 is an explanatory diagram showing a non-operating state, FIG. 11 is an explanatory diagram showing a state of the antilock brake system 10 at the time of decompression
FIG. 12 is an explanatory diagram showing a state of the antilock brake system 10 when holding, and FIG. 13 is an explanatory diagram showing a state of the antilock brake system 10 when increasing pressure. 10 to 13 show only the right front wheel system and omit the left front wheel system and the left and right rear wheel systems, these wheel systems operate similarly to the right front wheel system.

When the antilock brake system 10 is not operated, the holding solenoid valve 2 is operated as shown in FIG.
2 and the pressure reducing solenoid valve 32 are both turned off. That is, the port 22E of the holding solenoid valve 22 is opened and the port 32E of the pressure reducing solenoid valve 32 is closed. Therefore, when the brake fluid in the brake master cylinder 14 is boosted by depressing the brake pedal 12, the brake fluid is supplied to the pipe 1 as shown by the arrow in the figure.
6, the holding solenoid valve 22, the pipe 62, and the wheel cylinder 92 are sent to the wheel cylinder 92. At this time, the brake fluid is not blocked and sent to the pump 47 side by the check valve 48. Further, since the port 32E of the pressure reducing solenoid valve 32 is closed, the brake fluid will not be sent to the reservoir 40. When the brake pedal 12 is released, the brake fluid in the wheel cylinder 92 is pipe 62, the holding solenoid valve 22, the pipe 16, the brake master cylinder 1
It is returned to the brake master cylinder 14 by the route of 4. At this time, the check valve 2 of the holding solenoid valve 22
2D also opens, so port 22E and check valve 22D
The brake fluid is returned to the brake master cylinder 14 through and.

When the antilock brake system 10 is depressurized during operation, both the holding solenoid valve 22 and the depressurizing solenoid valve 32 are turned on, as shown in FIG. That is, the port 22E of the holding solenoid valve 22 is closed and the port 32E of the pressure reducing solenoid valve 32 is open. Therefore, the brake fluid in the wheel cylinders 92 is the pipe 62, the branch pipe 62A,
The pressure reducing solenoid valve 32, the branch pipe 43A, the connecting pipe 43, and the reservoir 40 are sent to the reservoir 40.

At this time, the pressure P acting on the brake fluid at the position of the opening 40B of the reservoir 40 can be the pressure P1 (the pressure based on the own weight of the piston 42) regardless of the stroke position of the piston 42. Even if the stroke position of the piston 42 varies depending on the amount of brake fluid sent, the pressure at which the brake fluid in the wheel cylinder 92 can be reduced (pressure that can be reduced) does not change. FIG. 14 shows a graph illustrating the relationship between the piston stroke position x and the depressurizable pressure P between the reservoir 40 of the present embodiment and the conventional reservoir in which the piston is biased by a spring. In the figure, the straight line A shows the relationship shown by the reservoir 40 of this embodiment, and the straight line B shows the relationship shown by the conventional reservoir. In both reservoirs, the depressurizable pressure P at the initial value (x = 0) of the stroke position x of the piston is set to the minimum pressure p required to push the brake fluid into the pump 47. As shown in the figure, in the reservoir 40 of this embodiment, the depressurizable pressure P is constant at the pressure p regardless of the stroke position x of the piston 42. In the conventional reservoir, when the stroke position x of the piston is different, the urging force of the spring changes, so the depressurizable pressure P also changes. The inclination of the straight line B is determined by the spring constant of the spring that biases the piston.

Therefore, in the conventional reservoir, when the brake fluid pressure in the wheel cylinder 92 is reduced, the calculation of the reduced pressure of the brake fluid is performed by the wheel cylinder 92.
Of the brake fluid pressure and the depressurizable pressure P that changes depending on the stroke position x of the piston are used as variables, and therefore the control logic necessary for the calculation (the time for which the depressurizing solenoid valve 32 is turned on to obtain a desired depressurizing amount) The logic required to compute) becomes complex. In contrast,
In the reservoir 40 of the present embodiment, the depressurizable pressure P is constant irrespective of the stroke position x of the piston 42, and therefore the depressurization amount of the brake fluid may be calculated using only the brake fluid pressure of the wheel cylinder 92 as a variable. As a result, the control logic is simpler than conventional reservoirs.

At the time of depressurization, the brake fluid in the reservoir 40 is pumped to the pipe 16 on the brake master cylinder 14 side by the pump 47 that is simultaneously operated when the antilock brake system 10 is operated. Further, when the brake pedal 12 is released, the brake fluid pressure on the pipe 16 side becomes smaller than the brake fluid pressure on the pipe 62 side, so the check valve 22D of the holding solenoid valve 22.
The brake fluid in the wheel cylinder 92 is returned to the brake master cylinder 14 through the check valve 22D.

When the antilock brake system 10 is held during operation, as shown in FIG. 12, the holding solenoid valve 22 is turned on, the pressure reducing solenoid valve 32 is turned off, and the ports 22E and 32E of both valves are turned on.
Are both closed. Therefore, the brake fluid in the wheel cylinder 92 is held in that state without being pressurized or depressurized. When the brake fluid is stored in the reservoir 40, the brake fluid is stored in the piston 42.
It is pushed into the pump 47 by the pressure based on its own weight, and is pumped to the pipe 16 on the brake master cylinder 14 side by the pump 47. Brake pedal 1 in this holding state
When 2 is released, the check valve 22D of the holding solenoid valve 22 is opened as described above, and the brake fluid in the wheel cylinder 92 is returned to the brake master cylinder 14.

When the antilock brake system 10 is actuated, as shown in FIG. 13, both the holding solenoid valve 22 and the pressure reducing solenoid valve 32 are turned off as shown in FIG.
The second port 22E is opened, and the port 32E of the pressure reducing solenoid valve 32 is closed. For this reason, the brake fluid in the brake master cylinder 14 that has been boosted by the depression of the brake pedal 12 is transferred to the wheel cylinder 92.
Sent to When the brake fluid is stored in the reservoir 40, it is returned to the brake master cylinder 14 side by the pump 47 as in the case of holding the brake fluid. When the brake pedal 12 is released, the brake fluid is returned to the brake master cylinder 14 through the port 22E and the check valve 22D as in the non-operation.

According to the reservoir 40 for the brake fluid pressure control device of the embodiment described above, the depressurizable pressure P of the brake fluid in the wheel cylinder 92 can be made constant regardless of the stroke position x of the piston 42. . As a result, when depressurizing the brake fluid in the wheel cylinder 92,
As compared with the conventional reservoir that biases the piston with a spring, the control logic required to calculate the pressure reduction amount can be simplified. Further, the reservoir 40 of the embodiment is a cylinder 40A.
Since only the piston 42 is used, the number of constituent parts can be reduced and the assembling can be performed easily. As a result, the cost can be reduced.

In the preferred embodiment, the piston 42 of the reservoir 40 is
Although it is made of aluminum, it is also preferable to use another material such as aluminum alloy, steel, steel alloy, resin or the like. Further, in the embodiment, the cylinder 4 of the reservoir 40
The opening 40B of 0A is formed in the center of the vertical lower surface of the cylinder 40A, but it may be formed at any position where the brake fluid can push the piston 42 upward and flow into the cylinder 40A. Furthermore, in the embodiment, the storage space of the cylinder 40A has a columnar shape, but it may have an elliptic cylinder shape or a polygonal cylinder shape. In the embodiment, the pressure P2 based on the own weight of the piston 42 is set to 0.2 MPa, but the pressure is not limited to this value as long as it is equal to or higher than the pressure of the brake fluid required on the inflow side that is determined by the performance of the pump 47.

Next, a reservoir 200 for a brake fluid pressure control device, which is a second embodiment of the present invention, will be described.
The reservoir 200 of the second embodiment is similar to the reservoirs 40 and 50 of the antilock brake system 10 of the first embodiment.
Used in place of. FIG. 15 is an explanatory view illustrating the structure of the reservoir 200 of the second embodiment.

As shown in the figure, the reservoir 200 comprises a cylinder 210 having a cylindrical storage space, a piston 220 that is fitted in the cylinder 210 in a liquid-tight and slidable manner, and a spring 230 that urges the piston 220. Become. Cylinder 2
10 has its axis arranged in the horizontal direction, and the piston 2
20 slides horizontally (left and right in the figure). An opening 212 capable of introducing the brake fluid is formed at one end (right end in the drawing) of the cylinder 210, and an opening 214 capable of introducing atmosphere is formed at the other end (left end in the drawing). .
End surface 2 of cylinder 210 having opening 212 formed therein
16 is magnetized to the south pole.

The piston 220 is made of steel. A skirt portion 224 is formed on the piston 220, and the skirt portion 224 guides a spring 230 that biases the piston 220. The piston 220 is
The end surface 222 is fitted into the cylinder 210 such that the end surface 222 faces the end surface 216 of the cylinder 210, and is biased rightward in the drawing by a spring 230 guided by a skirt portion 224. The end surface 222 of the piston 220 is magnetized to the N pole. Therefore, magnetic force (attractive force) is generated between the end surface 222 and the end surface 216 of the cylinder 210 magnetized to the S pole.
Occurs, and the piston 220 is pulled rightward in the figure. An O-ring 226 is provided on the outer circumferential edge of the piston 220.
Is installed.

The operation of the reservoir 200 will be described by replacing it with the reservoir 40 in the antilock brake system 10 of the first embodiment. Although only the right front wheel system will be described below, the same applies to the left front wheel system and the left and right rear wheel systems.

Similar to the reservoir 40 of the first embodiment, the reservoir 200 is turned on when the antilock brake system 10 is depressurized, the depressurizing solenoid valve 32 is turned on, the port 32E is opened, and the pipe 62 and the connecting pipe 43 are provided. Etc. to the wheel cylinder 92.
When connected to the wheel cylinder 92, the brake fluid moves the piston 220 leftward in FIG. 15 through the opening 212 and flows into the cylinder 210. At this time, in the brake fluid in the cylinder 210, the pressure P3 based on the spring 230 that acts on the piston 220 in the right direction in the drawing, the end surface 216 of the cylinder 210 and the end surface 222 of the piston 220 that also act in the right direction in the drawing, are generated. The pressure P, which is the sum of the pressure P4 and the pressure P4 based on the magnetic force (attractive force) generated in, acts. In Figure 16,
An example of the relationship between the stroke position x of the piston 220 and the pressure (pressure that can be reduced) P acting on the brake fluid is shown. In the figure, a straight line C is a change in the pressure P3 based on the spring 230, a curve D is a change in the pressure P4 based on the magnetic force, and a curve E is a change in the pressure P obtained by adding the pressures P3 and P4. Further, in the figure, the alternate long and short dash line F indicates that the pressure acting on the brake fluid becomes the value p when the stroke position x of the piston 220 has a value of 0 and a spring having the same spring constant as the spring 230 does not generate magnetic force. It is a change in the pressure P using the set reservoir.

As shown in the figure, the pressure P3 based on the spring 230 is proportional to the product of the spring constant k of the spring 230 and the stroke position x of the piston 220, and the pressure P4 based on the magnetic force is the square of the stroke position x of the piston 220. Since it is inversely proportional to, the depressurizable pressure P becomes a gentle curve with the minimum value as the value p in the range where the stroke position x of the piston 220 is the value x1 or less, and has a substantially constant value compared with the one-dot chain line F. You can say to show. Therefore, the piston 220
If the reservoir 200 is designed so that the stroke is less than or equal to the value x1, the depressurizable pressure P can be made substantially constant regardless of the stroke position x of the piston 220. The minimum value p is set to a pressure required to push the brake fluid, which is the minimum value of the depressurizable pressure P, into the pump 47.

The reservoir 200 of the second embodiment described above
According to the above, the depressurizable pressure P can be made substantially constant regardless of the stroke position x of the piston 220. Therefore, if the depressurizable pressure P is treated as a constant value, the control logic required to calculate the depressurization amount can be simplified when depressing the brake fluid pressure of the wheel cylinder.
In addition, in the second embodiment, the sliding direction of the piston 220 is the direction along the horizontal direction, but it may be any direction.

Next, a reservoir 300 for a brake fluid pressure control device, which is a third embodiment of the present invention, will be described.
The reservoir 300 of the third embodiment is similar to the reservoirs 40 and 50 of the antilock brake system 10 of the first embodiment.
Used in place of. FIG. 17 is an explanatory view illustrating the structure of the reservoir 300 of the third embodiment.

As shown in the figure, the reservoir 300 includes a cylinder 310 having a cylindrical storage space, a piston 320 fitted in the cylinder 310 so as to be liquid-tight and slidable, and a spring 330 for urging the piston 320. Become. Cylinder 3
The axis of the piston 10 is arranged vertically, and the piston 3
20 slides in the vertical direction (vertical direction in the figure). An opening 312 that allows the brake fluid to be introduced is formed in the vertically upper portion of the cylinder 210, and an opening 314 that allows the atmosphere to be introduced is formed in the vertically lower portion.

A skirt portion 324 is formed on the piston 320, and the skirt portion 324 is used to form the piston 320.
It guides the spring 330 for biasing. Piston 32
No. 0 is inserted into the cylinder 310 such that its end surface 322 faces the end surface 316 of the cylinder 310, and is biased upward in the drawing by the spring 330 guided by the skirt portion 324. An O-ring 326 is attached to the outer circumferential edge of the piston 320.

As the spring 330, a spring whose spring constant k is expressed by the following equation (1) is used. Here, the specific gravity of the brake fluid is γ, the cross-sectional area of the cylinder 310 is S, the stroke position of the piston 320 is x, and the gravitational acceleration is g. As the spring 330, a spring whose natural length L is expressed by the following equation (2) is used. Here, the spring length when the stroke position x is 0 is L1, and the length contracted to balance with the weight of the piston 320 is L2 = Mg /
k, the length required for the pressure p to act on the brake fluid is L
3 = pS / k. The spring force F of the spring 330 at the stroke position x is expressed by the following equation (3).

K = Sxγg ÷ x = Sγg (1) L = L1 + L2 + L3 = L1 + (Mg / k) + (pS / k) (2) F = k (L2 + L3 + x) = Mg + pS + kx (3)

At the stroke position x, the brake fluid pressure P in the opening 312 (pressure that can be reduced) is determined by the force (Mg) in the first term of the above equation (3) of the spring force F being the weight of the piston 320. In balance, the force (kx) of the third term is the self-weight (Sxγ) of the brake fluid in the cylinder 310 as shown in the equation (1).
g), the pressure p is based on the force (pS) of the second term. Since the force (pS) of the second term is independent of the stroke position x, the depressurizable pressure P is always a constant pressure p.

The reservoir 300 of the third embodiment described above
According to the above, the depressurizable pressure P can be made constant regardless of the stroke position x of the piston 320. As a result, when reducing the brake fluid pressure of the wheel cylinder,
It is possible to simplify the control logic required to calculate the pressure reduction amount.

The embodiments of the present invention have been described above.
The present invention is not limited to these examples, and it is needless to say that the present invention can be implemented in various modes without departing from the scope of the present invention, such as a configuration applied to a reservoir used for traction control. Is.

[0053]

As described above, according to the brake fluid pressure control device reservoir of the present invention, the pressure acting on the brake fluid in the cylinder is made substantially constant regardless of the position of the piston in the sliding direction. You can As a result, when the brake fluid pressure of the wheel cylinder is reduced, the control logic required to calculate the reduced pressure amount can be facilitated.

If the reservoir for the brake fluid pressure control device that applies pressure to the brake fluid in the cylinder by the weight of the piston is used, the number of parts constituting the reservoir can be reduced. As a result, the assembly can be facilitated and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating an outline of an antilock brake system 10 including a reservoir for a brake fluid pressure control device, which is a preferred embodiment of the present invention.

FIG. 2 is a block diagram illustrating an outline of an antilock brake system 10 centering on an ABS actuator 20.

FIG. 3 is an explanatory view showing a state when a holding solenoid valve 22 is off.

FIG. 4 is an explanatory diagram showing a state when the holding solenoid valve 22 is on.

FIG. 5 is an explanatory diagram showing a state when the pressure reducing solenoid valve 32 is off.

FIG. 6 is an explanatory diagram showing a state when the pressure reducing solenoid valve 32 is on.

FIG. 7 is an explanatory diagram illustrating the structure of a reservoir 40.

FIG. 8 is an explanatory diagram showing an operating state of the reservoir 40.

9 is a block diagram showing an electrical configuration of a control system centering on the ABS computer 100. FIG.

FIG. 10 is an explanatory diagram showing a state when the antilock brake system 10 is not operating.

FIG. 11 is an explanatory diagram showing a state of the antilock brake system 10 during depressurization.

FIG. 12 is an explanatory diagram showing a state when the antilock brake system 10 is held.

FIG. 13 is an explanatory diagram showing a state when the antilock brake system 10 is pressure-increased.

FIG. 14 is a graph illustrating the relationship between the piston position and the depressurizable pressure of the reservoir 40 of the embodiment and the conventional reservoir in which the piston is biased by a spring.

FIG. 15 is an explanatory diagram illustrating the structure of a reservoir 200 according to a second embodiment.

16 is a graph showing an example of the relationship between the stroke position x of the piston 220 and the depressurizable pressure P. FIG.

FIG. 17 is an explanatory diagram illustrating the structure of a reservoir 300 according to a third embodiment.

[Explanation of symbols]

 10 ... Anti-lock brake system 12 ... Brake pedal 14 ... Brake master cylinder 16, 18 ... Pipe 20 ... ABS actuator 22-28 ... Holding solenoid valve 22A, 32A ... Plunger 22B, 32B ... Spring 22C, 32C ... Coil 22D ... Check valve 22E, 32E ... Ports 22F, 32F ... Orifices 32 to 38 ... Pressure reducing solenoid valves 40, 50 ... Reservoirs 40A ... Cylinder 40B ... Openings 40C ... Openings 42 ... Pistons 42A ... O-rings 43, 53 ... Communication pipes 43A, 43B, 53A, 53B ... Branch pipe 44, 54 ... Return pipe 46, 56 ... Check valve 47, 57 ... Pump 48, 58 ... Check valve 62-68 ... Pipe 62A-68A ... Branch pipe 69 ... Proportioning valve 72-78 ... Wheels 82-88 ... Speed sensor 92-98 ... Wheel cylinder 100 ... ABS computer 102 ... CPU 104 ... ROM 106 ... RAM 108 ... Input interface circuit 110 ... Output interface circuit 112 ... Power supply circuit 200 ... Reservoir 210 ... Cylinder 212 ... Opening part 214 ... Opening part 216 ... End face 220 ... Piston 222 ... End face 224 ... Skirt part 226 ... O-ring 300 ... Reservoir 310 ... Cylinder 312 ... Opening part 314 ... Opening part 316 ... End face 320 ... Piston 322 ... End face 324 ... Skirt 326 ... O-ring

Claims (2)

[Claims] 1. A reservoir used for a brake fluid pressure control device for controlling the pressure of brake fluid in a wheel cylinder, the reservoir being a reservoir for temporarily storing the brake fluid, the cylinder being fluid-tight and sliding on the cylinder. A reservoir for a brake fluid pressure control device, comprising: a piston that can be inserted and inserted; and a pressurizing unit that applies a substantially constant pressure to the brake fluid in the cylinder regardless of the position of the piston in the sliding direction. 2. The reservoir according to claim 1, wherein the cylinder is arranged so that the piston slides in a vertical direction, and has an introduction path for introducing the brake fluid from a vertically lower portion, The means is a brake fluid pressure control device reservoir which is a means for applying a substantially constant pressure to the brake fluid by the weight of the piston.