JPH06340253A - Liquid-operated assistor device for brake - Google Patents

Abstract

PURPOSE:To compose a device at a low cost without high working accuracy by providing a control part sensing the stroke or load of an input piston to control first and second control valves. CONSTITUTION:The pressure in a second liquid-pressure chamber 60 is controlled higher always than that in a first liquid-pressure chamber 50. Consequently a partitioning wall piston 7 is made into a stationary condition where the piston 7 is made to abut on the right end part of a large-diameter cylinder 3. When a liquid-pressure source 11 is directly pushed leftward by an input piston 4. A power piston 5 is moved leftward together with the partitioning wall piston 7 against a spring 53, and a master cylinder 6 is pushed by the power piston 5 to operate a brake.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic booster for a brake used in a vehicle.

[0002]

2. Description of the Related Art Generally, in a vehicle brake, the pedaling force of a brake pedal and its stroke are related as shown in FIG. As is clear from the figure, when a certain stroke is reached, the movement of the brake pedal is limited even if the pedaling force of the brake pedal is increased. However, this is not necessarily an ideal characteristic, and various mechanisms have been proposed to improve this characteristic.

For example, the one shown in FIG. 10 is one in which an arbitrary characteristic can be obtained in the depression force of the brake pedal and its stroke, and a function of boosting hydraulic pressure is provided. The mechanical feature of this conventional example is that the small diameter cylinder 30 is provided in the casing 1.
And a large diameter cylinder 31 communicating with this small diameter cylinder 30.
And the input piston 32 for activating the brake system is slidably fitted into the small diameter cylinder 30, and the power piston 33 is attached to the large diameter cylinder 31.
The power piston 33 operates the master cylinder.

The large-diameter cylinder 31 has a partition wall 34 in the middle thereof so as to be fitted onto a medium-diameter portion 35 formed on the power piston 33. A liquid chamber 36 is provided between the partition wall 34 and the power piston 33, and the liquid pressure source 11 is provided therein.
The hydraulic pressure is applied via the valve 38. The pressure reduction is performed by the valve 39.

The power piston 33 is provided with a cylinder 37 which is fitted onto the input piston 32. As a result, the input piston 32 is configured to be fitted into the cylinder 37 and the small diameter cylinder 30, respectively, and to operate.

[0006]

However, in the above-mentioned conventional one, the smooth operation cannot be achieved unless the input piston 32 is coaxially and precisely fitted into the cylinder 37 and the small diameter cylinder 30, respectively. There is a problem that high processing accuracy is required and the cost becomes high.

The present invention has been made in view of the above matters, and an object of the present invention is to provide a hydraulic booster for a brake, which does not require high processing accuracy and can be constructed at low cost.

[0008]

The present invention has the following constitution in order to solve the above technical problems. That is, a small diameter cylinder 2 and a large diameter cylinder 3 communicating with the small diameter cylinder 2 are provided in the casing 1, and the small diameter cylinder 2
Input piston 4 for activating master cylinder 6
Is slidably fitted inside, and the power piston 5 is slidably fitted into the large diameter cylinder 3 so that the power piston 5 and the master cylinder 6 are interlocked.

In the large diameter cylinder 3,
A partition piston 7 is slidably fitted between the input piston 4 and the power piston 5, and a first control valve 9 for controlling the pressure between the partition piston 7 and the input piston 4, and the power piston. 5 and a second control valve 10 for controlling the pressure between the partition piston 7 and a hydraulic pressure source 1 for applying hydraulic pressure to these first and second control valves 9, 10.
1 and a control unit 12 that senses the stroke or load of the input piston 4 and controls the first and second control valves 9 and 10.

The first and second control valves 9 and 10 are
Can be composed of a pressurizing valve and a pressure reducing valve, respectively. A second piston is provided on a surface of the partition wall piston 7 facing the input piston 4 side, which is capable of contacting the input piston 4 and retractable, and which is capable of locking the first piston 13 at a protruding position. 14, the input piston 4 pushes the first piston 13 to operate the power piston 5 when the hydraulic pressure source 11 fails.

Further, a third piston 15 which is retractable within the stroke of the input piston 4 is provided on the surface of the partition wall piston 7 facing the input piston 4 side, and the third piston 15 is projected when the hydraulic pressure source 11 fails. Then, the power piston 5 may be operated by bringing the third piston 15 into contact with the input piston.

Further, a recess 8 to be a liquid chamber may be formed on the surface of the power piston 5 facing the partition piston 7 side.

[0013]

Since the input piston 4 and the power piston 5 are separated by the partition piston 7, it is not necessary to coaxially fit the input piston and the power piston as in the conventional case, and the machining accuracy is increased so much. Even without it, it is possible to perform a smooth operation.

Further, since the complicated fitting relationship of the piston and the like is eliminated, the number of packings can be reduced. Also,
When the hydraulic pressure source 11 fails, the movement of the input piston 4 is transmitted to the power piston 5 via the partition piston 7,
Braking never fails.

[0015]

Embodiments of the present invention will be described with reference to FIGS. <First Embodiment> A small diameter cylinder 2 and a large diameter cylinder 3 having one end communicating with the small diameter cylinder 2 are provided in the casing 1. A medium-diameter cylinder 20 is connected to the other end of the large-diameter cylinder 3, and a master cylinder 6 that generates hydraulic pressure to a wheel cylinder (not shown) is provided in the medium-diameter cylinder 20. ing.

An input piston 4 is provided in the small diameter cylinder 2.
Is provided slidably. This input piston 4
Is for activating the brake system, and is operated in conjunction with the brake pedal 21. A packing 4a is provided around the input piston 4. A load cell 21a is provided between the brake pedal 21 and the input piston 4 so that the force applied to the brake pedal 21 can be output as an electric signal.

A stroke sensor 21b is provided in the input piston 4 so that the stroke of the input piston 4 can be output as an electric signal.

The signals from the load cell 21a and the stroke sensor 21b are input to the control unit 12 which is composed of, for example, a microcomputer having an 8-bit central processing unit (CPU).

On the other hand, a power piston 5 is slidably fitted in the large diameter cylinder 3. The power piston 5 is in contact with the master cylinder 6 so that the pressing force can be transmitted to the master cylinder 6. A spherical recess 8 is formed on the surface of the power piston 5 facing the partition piston 7, and the recess 8 serves as a hydraulic chamber. A packing 5a is provided around the power piston 5 to maintain liquid tightness.

In the large diameter cylinder 3, a partition piston 7 is slidably fitted between the input piston 4 and the power piston 5. A packing 7a is provided around the partition piston 7 to block the input piston 4 side and the power piston 5 side in the casing 1 from each other.

A first hydraulic chamber 50 is formed between the partition piston 7 and the input piston 4. Then, in the casing 1 at a position corresponding to the first hydraulic chamber 50,
A first liquid inlet 69a for supplying the pressure liquid into the first liquid pressure chamber 50 and a first liquid discharge port 69b for discharging the pressure liquid in the first liquid pressure chamber 50 are provided. .

A first solenoid valve 9 as a first control valve for controlling the pressure P ₁ of the first hydraulic chamber 50 is connected to the first liquid inlet 69a and the first liquid outlet 69b. Has been done. A hydraulic pressure source 11 for applying hydraulic pressure is connected to the first solenoid valve 9, and the first solenoid valve 9 is controlled to be opened / closed by a command from the control unit 12. Here, the first electromagnetic valve 9 is composed of a first liquid inflow electromagnetic valve 9a and a first liquid outflow electromagnetic valve 9b, and the first liquid inflow electronic valve 9a is in the first liquid flow. The first liquid discharge electromagnetic valve 9b is connected to the inlet 69a, and is connected to the first liquid discharge port 69b.

A second hydraulic chamber 60 is formed between the power piston 5 and the partition piston 7. Then, the casing 1 at a position corresponding to the second hydraulic chamber 60
A second liquid inflow port 70a for supplying the pressure liquid into the second hydraulic pressure chamber 60 and a second liquid discharge port 70b for discharging the pressure liquid in the second hydraulic pressure chamber 60 are provided therein. Has been.

A second solenoid valve 10 serving as a second control valve for controlling the pressure P ₂ of the second hydraulic chamber 60 is connected to the second liquid inlet 70a and the second liquid outlet 70b. Has been done. The hydraulic pressure source 11 is also connected to the second electromagnetic valve 10, and the opening / closing of the second electromagnetic valve 10 is controlled by a command from the control unit 12. Here, the second electromagnetic valve 10 is composed of a second liquid inflow electromagnetic valve 10a and a second liquid outflow electromagnetic valve 10b, and the second liquid inflow electronic valve 10a is in the second liquid flow. The second liquid discharge solenoid valve 10b is connected to the inlet 70a, and is connected to the second liquid discharge port 70b.

Next, the operation of the first embodiment will be described. FIG. 1 shows a state in which the brake pedal 21 is not depressed.
At this time, the power piston 5 and the partition piston 7 are urged toward the right end side of the large diameter cylinder 3 in the figure by the spring 53 in a state where they are in contact with each other. That is, the right end of the power piston 5 contacts the left end of the partition cylinder 7,
The right end of the partition cylinder 7 is in contact with the right end of the large diameter cylinder 3.

As shown in FIG. 2, when the driver depresses the brake pedal 21, the load cell 21a outputs a signal corresponding to the pedaling force to the control unit 12. At the same time, a signal corresponding to the stroke amount from the stroke sensor 21b is output to the control unit 12. Control unit 12
Is the first solenoid valve 9 (first liquid inflow solenoid valve 9) so as to match a preset pedal depression force-stroke diagram.
The opening and closing of a and the first liquid discharge solenoid valve 9b) are controlled. That is, when increasing the pressure P ₁ in the first hydraulic pressure chamber 50, the hydraulic pressure from the hydraulic pressure source 11 is supplied to the first hydraulic pressure chamber 50 via the first hydraulic fluid inflow solenoid valve 9a. When lowering the pressure P ₁ in the first hydraulic chamber 50, the pressurized liquid in the first hydraulic chamber 50 is discharged via the first liquid discharging electromagnetic valve 9b.

Further, the controller 12 controls the second solenoid valve 10 (the second solenoid valve 10a for inflowing the second fluid and the second solenoid valve 10a) in order to obtain a predetermined brake fluid pressure suitable for the pedal stroke and the pedal effort.
The opening and closing of the liquid discharge solenoid valve 10b) is controlled. That is, when increasing the pressure P ₂ in the second hydraulic chamber 60, the hydraulic pressure source 11
Is supplied to the second hydraulic chamber 60 via the second liquid inflow solenoid valve 10a. In addition, the pressure P in the second hydraulic chamber 60
_{When the value of 2} is decreased, the pressurized liquid in the second hydraulic pressure chamber 60 is discharged via the second liquid discharge electromagnetic valve 10b.

When the pressure P ₂ in the second hydraulic chamber 60 is increased, the power piston 5 moves leftward against the spring 53 and pushes the master cylinder 6 toward the wheel cylinder (not shown). Increase the supplied brake fluid pressure. Further, when the pressure P ₂ of the second hydraulic chamber 60 decreases while the power piston 5 is pressing the master cylinder 6, the power piston 5 moves toward the input cylinder 4 by the urging force of the spring 53, The pressure on the cylinder 6 is weakened to reduce the brake fluid pressure on the wheel cylinder.

During braking, the pressure P _{2 in} the second hydraulic chamber 60 is always controlled to be higher than the pressure P _{1 in} the first hydraulic chamber 50. Therefore, the partition piston 7
Is in a stationary state while being in contact with the right end portion of the large diameter cylinder 3.

When the hydraulic pressure source 11 fails, the input piston 4 directly pushes the partition piston 7 to the left in the figure, as shown in FIG. Then, the power piston 5 moves leftward against the spring 53 together with the partition piston 7, and the power piston 5 presses the master cylinder 6 to operate the brake.

<Embodiment 2> In this embodiment, as the first solenoid valve 9 and the second solenoid valve 10, as shown in FIG. 4, pressure servo valves capable of pressurizing and depressurizing are used, respectively. Shows. Since other configurations are similar to those of the first embodiment, description thereof will be omitted.

<Third Embodiment> This embodiment is an improvement of the first embodiment. In the first embodiment, a stroke space is provided between the partition piston 7 and the input piston 4 in order to secure a control range. However, when the hydraulic pressure source 11 fails, the loss stroke becomes large, which is necessary. It may not be possible to obtain sufficient braking force. Therefore, in the third embodiment, the loss stroke is reduced.

That is, as shown in FIG. 5, on the surface of the partition wall piston 7 facing the input piston 4 side, a first piston 13 that can come into contact with the input piston 4 and is retractable is provided. As shown in FIG. 6, the first piston 13 is biased toward the input piston 4 by a coil spring 13a, and a communication hole 13b is formed inside.

The partition piston 7 is provided with a plurality of second pistons 14 which are orthogonal to the first pistons 13. The second pistons 14 are first pistons as shown in FIG.
The piston 13 is provided so that it can be retracted so that it can be locked at the protruding position. The second piston 14 has a sealing material 14a and is biased in a projecting direction by a return spring 14b, and projects when the pressure P ₁ of the first hydraulic chamber 50 between the partition piston 7 and the input piston 4 is low. It will be in the state of doing.

The operation of the third embodiment will be described. In this example,
At normal time (when boosting operation), when the brake pedal is depressed and the input piston 4 moves toward the partition piston 7,
Since the pressure P ₁ of the first hydraulic chamber 50 rises, the second piston 14 is pushed against the return spring 14b (FIG. 7). Therefore, the first piston 13 is in a free state, and the stroke of the input piston 4 is secured. Since the portion in which the coil spring 13a is housed and the first hydraulic chamber 50 communicate with each other through the communication hole 13b, when the first piston 13 is pressed by the input piston 4, the first piston 13 Moves smoothly in the direction of the power piston 5 (to the left).

On the other hand, when the hydraulic pressure source 11 fails, the control unit 1
2 detects the pressure of the hydraulic pressure source 11 and each solenoid valve is not controlled. That is, the first liquid discharge solenoid valve 9b remains open. Therefore, even if the brake pedal is depressed and the input piston 4 moves toward the partition piston 7, the pressure fluid in the first fluid pressure chamber 50 remains in the first fluid discharge solenoid valve 9
After being discharged from b, the pressure P ₁ does not change.

Therefore, the second piston 14 is not pushed in and the first piston 13 is locked,
The input piston 4 presses the first piston 13 so that the operation at the time of failure can be performed without loss stroke.

In this way, when the hydraulic pressure source 11 fails, the input piston 4 pushes the first piston 13 in a protruding state,
Since the partition cylinder piston 7 and the power piston 5 are moved to operate the master cylinder 6, safety can be ensured.

<Embodiment 4> In this embodiment, as shown in FIG. 8, a third piston 15 which is retractable within the stroke of the input piston 4 is provided on the surface of the partition wall piston 7 facing the input piston 4 side. It is a thing. This third piston 15
Are provided opposite to each other. The third piston 15 is
The return spring 1 is provided with the sealing material 15a.
When the pressure P ₁ of the first hydraulic chamber 50 between the partition piston 7 and the input piston 4 is low, it is in a protruding state.

When the hydraulic pressure source 11 fails, the third piston 15
Is projected, the tip of the input piston 7 contacts the third piston 15, and the partition piston 7 and the power piston 5 are moved in the master cylinder direction to the left in the drawing. The other operations are the same as those in the third embodiment, and the description thereof will be omitted.

As described above, according to this embodiment, since the partition piston is provided, the sealability between the power piston and the input piston can be improved. Therefore, since it is not necessary to fit each piston coaxially, it is possible to manufacture a hydraulic booster for brake at low cost without requiring high processing accuracy.

When the hydraulic pressure source fails, the input piston 4
Is transmitted to the master cylinder 6 via the partition piston 7 and the power piston 5, so that braking can be reliably performed.

Furthermore, according to this embodiment, the pressure receiving area of the power piston can be formed to be substantially equal to the cross-sectional area of the large diameter cylinder. Therefore, the total length of the power piston can be shortened, and the casing can be formed to have a small diameter, so that the entire device can be made compact.

Incidentally, not the master cylinder but a rod interlocking with the master cylinder may be provided in the middle diameter cylinder 20.

[0045]

According to the present invention, it is possible to provide a brake hydraulic booster which can be constructed at low cost without requiring high machining accuracy.

[Brief description of drawings]

FIG. 1 is a sectional view showing a state in which a brake is not operated in a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a brake actuation according to the first embodiment.

FIG. 3 is a cross-sectional view showing a brake actuation at the time of hydraulic pressure source failure in the first embodiment.

FIG. 4 is a sectional view showing a second embodiment of the present invention.

FIG. 5 is a sectional view showing a third embodiment of the present invention.

FIG. 6 is a sectional view of an essential part for explaining the operation of the third embodiment of the present invention.

FIG. 7 is a sectional view of an essential part for explaining the operation of the third embodiment of the present invention.

FIG. 8 is a sectional view showing a fourth embodiment of the present invention.

FIG. 9 is a graph showing a relationship between a pedal effort and a stroke of a conventional brake.

FIG. 10 is a sectional view showing a conventional brake hydraulic booster.

[Explanation of symbols]

 1 ... Casing 2 ... Small diameter cylinder 3 ... Large diameter cylinder 4 ... Input piston 4a ... Packing 5 ... Power piston 5a ... Packing 6 ... Master cylinder 7 ... Bulkhead piston 7a ... Packing 8 ... Recess 9: First solenoid valve 9a: First liquid inflow solenoid valve 9b: First liquid discharge solenoid valve 10: Second solenoid valve 10a: Second liquid inflow solenoid valve 10b: Second Solenoid valve for liquid outflow ・ ・ Hydraulic pressure source 12 ・ ・ Control unit 13 ・ ・ First piston 13a ・ ・ Coil spring 13b ・ ・ Communication hole 14 ・ ・ Second piston 14a ・ ・ Seal material 14b ・ ・ Return spring 15 ・・ Third piston 15a ・ ・ Seal material 15b ・ ・ Return spring 20 ・ ・ Medium diameter cylinder 21 ・ ・ Brake pedal 21a ・ ・ Load cell 21b ・ ・ Stroke sensor 50 ・The first hydraulic chamber 60 ... second hydraulic pressure chamber 69a ... first liquid flow inlet 69b ... first liquid discharge port 70a ... second liquid flow inlet 70b ... second liquid outlet

Claims (4)

[Claims] 1. A small diameter cylinder (2) and a large diameter cylinder (3) communicating with the small diameter cylinder (2) are provided in the casing (1), and a master cylinder (6) is provided in the small diameter cylinder (2). The input piston (4) for starting is slidably fitted inside, and the power piston (5) is slidably fitted inside the large diameter cylinder (3) so that the power piston (5) and the master cylinder (6). ) Are interlocked, and a partition piston (7) is slidably fitted between the input piston (4) and the power piston (5) in the large diameter cylinder (3). A first control valve (9) for controlling the pressure between the input piston (4) and a second control valve (9) for controlling the pressure between the power piston (5) and the bulkhead piston (7). Control valve (10 ) And these first
And a hydraulic pressure source (11) for applying hydraulic pressure to the second control valve (9, 10) and the stroke or load of the input piston (4) to detect the first and second control valves (9, 10). 10)
A hydraulic booster for brake, comprising a control unit (12) for controlling the above. 2. The double hydraulic pressure for brake according to claim 1, wherein the first control valve (9) and the second control valve (10) are respectively composed of a pressurizing valve and a depressurizing valve. Force device. 3. A first piston (13) which can come into and out of contact with the input piston (4) is provided on the surface of the partition wall piston (7) facing the input piston (4) side, and the first piston (13) is provided. Second that can lock (13) at the protruding position
A piston (14) is provided, and the power piston (5) is operated by pushing the first piston (13) by the input piston (4) when the hydraulic pressure source (11) fails. The hydraulic booster for brakes according to claim 1. 4. A hydraulic pressure source (11) is provided with a third piston (15) which is retractable within the stroke of the input piston (4) on the surface of the partition wall piston (7) facing the input piston (4) side. The third piston (15) when the
The hydraulic booster for brakes according to claim 1, wherein a third piston (15) is brought into contact with the input piston (4) to activate the power piston (5).