JP2581968B2 - Fluid pressure booster - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention (1) Field of the Invention The present invention relates to a fluid pressure booster for boosting a master cylinder used in an automobile or the like by the fluid pressure of a fluid pressure source. It enables operation by input only even when the pressure source fails.

(2) Prior art Such a fluid pressure booster is already known, for example, as disclosed in Japanese Patent Application Laid-Open No. 60-107444.

The fluid pressure booster disclosed in the above publication causes the booster piston to advance by the fluid pressure of the fluid pressure source to generate hydraulic pressure in the brake hydraulic chamber of the master cylinder during normal boosting operation, and when the fluid pressure source fails, Then, an input is given to the booster piston via the input rod, and the booster piston is advanced in the same manner as in a normal state to generate a hydraulic pressure in the brake hydraulic chamber.

(3) Problems to be Solved by the Invention As described above, it is difficult to design a booster piston in a fluid pressure booster that operates the booster piston regardless of whether the fluid pressure source is normal or not. In other words, when the hydraulic pressure source is normal, if the booster piston is formed with a large diameter in order to minimize the stroke of the input rod, a large input is required for the operation of the master cylinder when the hydraulic pressure source fails. And Conversely, if the booster piston is formed to have a small diameter, the stroke of the input rod becomes longer even when the fluid pressure source is normal, and the operation feeling is impaired.

The present invention has been made in view of such circumstances, and operates a master cylinder with a relatively short stroke of an input rod when a fluid pressure source is normal, and operates a master cylinder with a relatively small input when a fluid pressure source fails. Can be
Moreover, it is an object of the present invention to provide a fluid pressure booster capable of accurately detecting the operation reaction force of the master cylinder.

B. Configuration of the Invention (1) Means for Solving the Problems In order to achieve the above object, the present invention provides an input fluid pressure chamber connected to a rear portion of a cylinder body of a master cylinder and connected to a hydraulic pressure source, and A booster body having an output fluid pressure chamber, and a booster piston slidably fitted in the booster body so that the front end faces the braking hydraulic chamber of the master cylinder and the rear end faces the output fluid pressure chamber. The front end faces the brake hydraulic chamber and is fitted to the booster piston.When the booster piston moves forward, the inner piston moves forward together with the booster piston but can move alone, and is slidably fitted in the inner piston. A valve piston for controlling opening and closing of a flow path between the input and output fluid pressure chambers by moving forward and backward with respect to the inner piston, and controlling opening and closing of a flow path between the output fluid pressure chamber and the fluid tank; And an input rod which is connected to the rear end of the piston, the inner piston, the first feature in that a reaction force fluid pressure chamber facing the front end of the valve piston in communication with the brake pressure chamber. Note that hydraulic pressure, air pressure, and the like are used as the fluid pressure.

In addition, the present invention, in addition to the features described above, the master cylinder is configured in a tandem type that houses a master piston that partitions the cylinder body into two chambers, a front brake hydraulic chamber and a rear brake hydraulic chamber, The front end of the booster piston faces the rear brake hydraulic chamber and the reaction force fluid pressure chamber communicates. The inner piston is mechanically connected between the inner piston and the master piston only when the rear brake hydraulic chamber system fails. A second feature is that a reaction force mechanism for mechanically transmitting a part of the operation reaction force of the master piston to the valve piston is provided.

(2) Operation In the first feature, if the input and output fluid pressure chambers communicate with each other by operating the valve piston by the input rod when the fluid pressure source is normal, the fluid pressure of the fluid pressure source can be changed from the input fluid pressure chamber to the output fluid. The booster piston is transmitted to the pressure chamber and receives this fluid pressure to move forward. At this time, since the booster piston accompanies the inner piston, both pistons pressurize the brake hydraulic chamber of the master cylinder. Therefore, the brake hydraulic chamber can be effectively pressurized with a relatively short stroke of the booster piston.

At this time, the hydraulic pressure in the brake hydraulic chamber is transmitted to the reaction force fluid pressure chamber and acts on the valve piston as a reaction force.

Further, if the input rod is advanced when the fluid pressure source fails, the input given to the input rod is directly transmitted to the inner piston to advance it. At this time, since the inner piston advances leaving the booster piston behind, the brake hydraulic chamber of the master cylinder is pressurized only by the inner piston. As a result, the stroke of the inner piston increases, but the input to the input rod is reduced accordingly.

In the second feature, when the booster piston is actuated when the rear brake hydraulic chamber system of the tandem type master cylinder fails, the inner piston that advances with it mechanically pushes the master piston via a reaction force mechanism, Enables pressurization of the partial braking hydraulic chamber. At this time, a part of the reaction force of the master piston is mechanically transmitted to the valve piston via the reaction force mechanism.

(3) Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, M is a tandem-type master cylinder for a two-system hydraulic brake of an automobile. Is formed. The inside of the oil tank 2, lower half is divided into a front oil reservoir 2 ₁ and the rear oil sump 2 ₂ by a partition wall 2a.

The cylinder hole 3 of the cylinder body 1 is provided with a small-diameter hole 3a passing directly below the oil tank 2 and a large-diameter hole 3b connected to the rear end of the small-diameter hole 3a. Cylinder bore 3 is partitioned by the master piston 4 slidably fitted in the small diameter hole 3a in the front brake hydraulic chamber 5 ₁ and the rear braking hydraulic chamber 5 _2, these braking hydraulic chamber 5 _1, 5 ₂ Through the output ports 6 ₁ , 6 ₂ , it is connected to two independent brake hydraulic circuits 7 ₁ , 7 ₂ .

A stop ring 8 for restricting the retreat limit of the master piston 4 is locked to the inner wall of the rear end portion of the small diameter hole 3a, and a return spring 9 for urging the master piston 4 toward the retreat limit is provided with a front brake hydraulic chamber 5 ₁
It is contracted.

The outer periphery of the master piston 4, which is annular oil supply chamber 10 which always communicates with the front brake hydraulic chamber 5 ₁ formation, known to open and close between the front brake hydraulic chamber 5 ₁ of the oil supply chamber 10 The center type relief port valve 11 is provided on the master piston 4. That is, the relief port valve 11 is in the retreat limit of the master piston 4 is communicating between the front brake hydraulic chamber 5 ₁ and replenishing oil chamber 10, during forward movement of the piston 4 to cut off between both chambers 5 _1, 10.

The front end of the booster body 20 of the fluid pressure booster B of the present invention is fitted and connected to the outer periphery of the rear end of the cylinder body 1. A front sleeve 21 abutting on the rear end of the cylinder body 1 and a rear sleeve 22 abutting on the rear end of the front sleeve 21 via a spacer 23 are fitted on the inner surface of the booster body 20. The front sleeve 21 is a large-diameter hole of the cylinder body 1.
It has a cylinder hole 24 following 3b and an inward flange 21a at the rear end. Further, the rear sleeve 22 has a cylinder hole 26 slightly larger in diameter than the inner hole 25 of the flange 21a.

The cylinder bore 24 of the front sleeve 21, the rear brake pressure chamber 5 ₂ booster piston 27 to face the front end portion is slidably fitted, the booster piston 27 abuts against the said flange 21a Limits the retreat limit.

The booster piston 27 has a front cylinder hole which has substantially the same diameter as the small diameter hole 3a of the cylinder body 1 and is opened on the front surface of the piston 27.
28a and a stepped cylinder hole having a smaller diameter and a rear cylinder hole 28b having the same diameter as the inner hole 25 of the flange 21a and having an opening at the rear surface of the piston 27. Inner piston 29 is slidably fitted.

The inner piston 29 has a stepped portion 29a whose booster piston 2
Is adapted to separably engage 7 of the stepped portion 27a, the spring 30 returns for biasing the inner piston 29 to the backward direction is disposed in said rear brake hydraulic chamber 5 _2.

As shown in FIG. 2, the inner piston 29 slidably penetrates the inner hole 25 of the flange 21a, loosely penetrates the cylinder hole 26 of the rear sleeve 22, and further includes a booster body.
The rear end wall 20 is slidably penetrated through the rear end wall, and the rear end protrudes rearward of the booster body 1 for a sufficiently long time.

The inner piston 29 is hollow, a valve piston 31 is provided in the hollow portion, and a cushion rubber 32 is provided at a front end of the valve piston 31.
Large-diameter input piston 33 abutting through the inner piston
An extension rod 34 connected to the front end of 29 and a reaction force mechanism 35 are provided. A stop ring 36 for restricting the retraction limit of the input piston 33 is locked to the rear end of the inner piston 29, and this stop ring
A valve spring 37 that resiliently extends the extension rod 34 toward 36 is housed in the inner piston 29. An input rod 39 operated by a brake pedal 38 is connected to the input piston 33.

Annular oil passages 40 and 41 are formed between the booster main body 20 and the front sleeve 21 and arranged in front and rear. An annular oil passage 42 is also formed between the booster main body 20 and the rear sleeve 22. The front part of the annular oil passage 40 in the rear oil reservoir 2 ₂ via the low pressure conduit 43, central annular oil passage 41 hydraulic pump 45 (FIG. 1 reference as a fluid pressure source through the high pressure line 44 1), the rear annular oil passage 42 communicates with an oil tank 47 (see FIG. 1) as a fluid tank via a second low-pressure conduit 46.

The central annular oil passage 41 communicates with the input hydraulic chamber 49 between the rear sleeve 22 and the inner piston 29, that is, the input fluid pressure chamber, via the radial oil passage 48 of the spacer 23.

The input hydraulic chamber 49 includes a front seal member 50 mounted on the flange 21a to make the inner peripheral lip closely contact the outer peripheral surface of the inner piston 29, and an outer peripheral lip mounted on the inner piston 29 and Rear sealing member to be in close contact with
Defined between 51 and. Therefore, the rear seal member 51
The outer peripheral lip has a larger diameter than the inner peripheral lip of the front seal member 50, so an axial thrust is generated between the seal members 50 and 51 by the hydraulic pressure of the input hydraulic chamber 49, and this thrust is It acts on the inner piston 29 via the rear seal member 51 as a retreating force.

The inner piston 29 is provided with a radial inlet port 52 connected to the input hydraulic chamber 49 and a radial outlet port 53 connected to the annular oil passage 42.

The valve piston 31 has a central land 55 as an inlet valve for opening and closing the inlet port 52, and a rear land 56 as an outlet valve for opening and closing the outlet port 53. An annular groove 58 defined between the lands 55 and 56 is connected to an output hydraulic chamber 60 facing the rear end face of the booster piston 27 through a series of oil passages 59 provided in the valve piston 31 and the inner piston 29. Communicate with fluid pressure chamber.

In the inner piston 29, a reaction force hydraulic chamber 61, that is, a reaction force fluid pressure chamber facing the front end face of the valve piston 31, is provided.
Communicates with the rear brake hydraulic chamber 5 ₂ through an oil passage 54.

Further, a radial relief port 62 that opens into the reaction force hydraulic chamber 61 is formed in the inner piston 29. The relief port 62 communicates with the annular oil passage 40 through a series of oil passages 63 provided in the front sleeve 21, the booster piston 27 and the valve piston 31, and a relief formed in the front of the valve piston 31. It is opened and closed by a front land 57 as a port valve.

The front land 57, the center land 55, and the rear land 56 of the valve piston 31 are arranged such that the opening / closing timing of the relief port 62, the inlet port 52, and the outlet port 53 is as follows. That is, when the valve piston 31 is located at the retreat limit, the relief port 62 and the outlet port 53 are in the open state, and the inlet port 52 is in the closed state.When the valve piston 31 advances from the retreat limit, first, the front land 57 The relief port 62 is closed, and the rear port 56 closes the outlet port 53 a little later, and after the outlet port 53 is completely closed, the central land 55 opens the inlet port 52.

Incidentally, the closing of the relief port 62 and the exit port 53 may be simultaneous.

The reaction force mechanism 35 has a collar 65 fitted in order from the back into a bottomed cylinder hole 64 opening at the front end surface of the inner piston 29,
The output piston 67 includes an elastic piston 66 and an output piston 67. The output piston 67 is prevented from falling out of the cylinder hole 64 by a retaining ring 68. A reaction force piston 69 facing the front end of the extension rod 34 is slidably fitted to the collar 65, and the reaction force piston 69 is formed to have a sufficiently smaller diameter than the elastic piston 66.

An output rod 70 protrudes from the front surface of the output piston 67, and the output rod 70 normally keeps a constant distance from the master piston 4.

Referring again to FIG. 1, an electric motor 71 for driving the hydraulic pump 45 is connected to the hydraulic pump 45.
Is connected to an accumulator 72.

 Next, the operation of this embodiment will be described.

1 and 2 when the brake pedal 38 is not actuated.
As shown in the figure, the valve piston 31 is held at the retreat limit by a valve spring 37, and the valve piston 31
62 and outlet port 53 are opened, and inlet port 52 is closed.

Thus retraction, since the rear brake hydraulic chamber 5 ₂ of the master cylinder M is in the atmospheric pressure state communicates with the rear oil sump 2 ₂ via the relief port 62 and the low-pressure conduit 43, the master piston 4 by a return spring 9 It is kept to the limit. Since this state relief port valve 11 is opened, the front brake hydraulic chamber 5 ₁ be passed through the front oil reservoir 2 ₁ and the communication has become atmospheric pressure.

On the other hand, the output hydraulic chamber 60 communicates with the oil tank 47 via the outlet port 53 and the second low-pressure conduit 46 and is in an atmospheric pressure state. The input hydraulic chamber 49 is held at the retreat limit by the return force of the hydraulic pressure.

During this time, in the input hydraulic chamber 49, the pressure oil sent from the hydraulic pump 45 and the accumulator 72 through the high-pressure conduit 44 waits.

Now, when the brake pedal 38 is depressed to brake the car, the valve piston 31 is input via the input rod 39 and the input piston 33.
Moves forward, firstly the relief port 62 is closed by the front land 57, then the outlet port 53 is closed a little later by the rear land 56, and finally the inlet port is closed by the central land 55.
52 is opened.

Then, the pressure oil waiting in the input hydraulic chamber 49 enters the output hydraulic chamber 60 from the inlet port 52 via the annular groove 58, and the booster piston 27 advances by receiving the hydraulic pressure. At this time,
The booster piston 27 and the inner piston 29 are
Since a and 29a are in contact, the booster piston 27 moves forward with the inner piston 29.

According to the advance of the pistons 27 and 29, since the relief port 62 as described above has already been closed, hydraulic pressure is generated in the rear braking oil pressure chamber 5 _2, master piston 4 receives the hydraulic pressure is advanced in front brake pressure chamber 5 ₁ to generate a hydraulic pressure.
As a result, hydraulic pressure is output from both output ports 6 ₁ and 6 ₂ , and both brake hydraulic circuits 7 ₁ and 7 ₂ can be operated simultaneously.

The advance of the booster piston 27 and the inner piston 29 stops when the inlet port 52 is closed by the central land 55 of the valve piston 31. That is, the booster piston 27 and the inner piston 29 follow the valve piston 31.

Incidentally, the booster piston 27 is formed sufficiently larger diameter than the master piston 4, according to the co-operation of such a booster piston 27 and inner piston 29, the rear brake pressure chamber 5 ₂ with a relatively short stroke Hydraulic pressure can be generated effectively. As a result, the stroke of the input rod 39, that is, the depression amount of the brake pedal is small, and the operation feeling is improved.

Further, since the relief port 62 is closed by the front land 57 of the valve piston 31 before advancing operation of the booster piston 27, booster piston 27 can be advanced and generates a hydraulic pressure in the rear brake hydraulic chamber 5 ₂ simultaneously, disabled There is almost no stroke. Besides, relief port by front land 57
The closing of the port 62 proceeds with the closing of the outlet port 53 by the rear land 56, so that the closing stroke of the relief port 62 does not increase the working stroke of the valve piston 31 and thus the input rod 39. In particular, the opening and closing control of the relief port 62, the inlet port 52, and the outlet port 53 by the three lands 57, 55, 56 formed on the same valve piston 31 as shown in the illustrated example, This is extremely effective in accurately obtaining the timing with a short working stroke of the valve piston 31.

During such normal braking, the output rod 70 does not come into contact with the master piston 4. And rear brake hydraulic pressure chamber 5 ₂
Is transmitted to the reaction force hydraulic chamber 61 through the oil passage 54, and acts on the front surface of the valve piston 31 to give a reaction force.

Thus even pressure oil is supplied to the output hydraulic pressure chamber 60, the valve piston 31 from the hydraulic pressure is generated in the rear braking oil pressure chamber 5 ₂ Advancement of the booster piston 27 will receive a reaction force,
In addition, since the valve piston 31 does not include a high-pressure seal member that generates a large frictional resistance, the received reaction force can be smoothly transmitted to the input rod 39, and as a result, the operation reaction force of the master cylinder M can be reduced. It is possible to accurately feed back to the operator via the brake pedal 38, and to accurately know the strength of the braking force.

During such braking, the Wakashi failure only to the brake hydraulic circuit ₇₁ of the front brake hydraulic chamber 5 ₁ system occurs, hydraulic pressure is not generated in the front brake hydraulic chamber 5 ₁ also by advancing the master piston 4 since, the booster piston 27 and inner piston to the master piston 4 abuts against the front end wall of the front brake hydraulic chamber 5 ₁
29 forward stroke of the idle stroke, but the rear brake pressure chamber 5 ₂ by advancing the subsequent pistons 27, 29 can generate a hydraulic pressure. The operation reaction force of the master cylinder M at this time is fed back to the input side via the oil pressure in the reaction force hydraulic chamber as in the normal case.

Further, when the failure only brake hydraulic circuit 7 ₂ of the rear brake hydraulic chamber 5 ₂ based on the opposite occurs with this, the hydraulic pressure is not generated in the rear brake pressure chamber 5 _2, the output rod 70 is master piston 4
The forward stroke of the booster piston 27 and the inner piston 29 until it comes into contact with the rear end becomes an invalid stroke,
Allowed forward subsequent advancement master piston 4 of the pistons 27 and 29, it is possible to generate a hydraulic pressure in the front brake hydraulic chamber 5 _1. At this time, the reaction force of the master cylinder M is generated by the elastic piston from the output rod 70 via the output piston 67.
The compression force is transmitted to the piston 66 and compressive deformation is applied to the piston 66.
And feedback to the valve piston 31 and to the input side.

Next, it is assumed that a defect occurs in a hydraulic path from the hydraulic pump 45 to the input hydraulic chamber 49. In this case, the input hydraulic chamber 49
, The booster piston 27 cannot move forward even if the valve piston 31 is advanced by opening the inlet port 52 by depressing the brake pedal 38.

Therefore, when the valve piston 31 advances by a predetermined amount with respect to the inner piston 29, the input piston 33 comes into contact with the inner piston 29, and the pedaling force applied to the brake pedal 38 is reduced by the inner piston 29.
The master cylinder M can be operated by only the pedaling force, that is, the input, by transmitting it to the motor 29 and moving it forward.

In this case, since the booster piston 29 it is left behind in the backward limit, thus pressurizing the rear brake hydraulic chamber 5 ₂ only inside the piston 29. Therefore, in order to obtain the same braking force, compared with the rear brake hydraulic chamber 5 ₂ during booster operation to pressurize the both the booster piston 27 and inner piston 29, although the stroke of the inner piston 29 increases, whereby the input Can be reduced.

Also, according to the advance of only the inner piston 29, its step
29a is separated from the step 27a of the booster piston 27,
27a, continue to increase the volume between 29a, but results in a negative pressure therein, that the volume is extremely small, the rear oil reservoir 2 _second oil low pressure conduit 43 with the generation of the negative pressure, the annular oil passage 42 and By being sucked between the two steps 27a and 29a via the oil passage 63,
The forward resistance given to the inner piston 29 under the negative pressure is small.

Also in this case, the hydraulic inner piston of the input hydraulic chamber 49
This also reduces the advancing resistance of the inner piston 29 since the return force on the 29 has also disappeared.

C. Effects of the Invention As described above, according to the first aspect of the present invention, when the fluid pressure source is normal, the brake hydraulic chamber of the master cylinder is pressurized by both the booster piston and the inner piston, and the fluid pressure source is lost. Since the braking hydraulic chamber is pressurized only by the inner piston at the time of a fall, the stroke of the input rod is shortened in a normal state to improve the operation feeling, and at the time of a fall, the input can be reduced.

In addition, when the fluid pressure source is normal, the hydraulic pressure in the brake hydraulic chamber generated by the operation of the booster piston acts on the valve piston as a reaction force, so that the pilot can accurately determine the operation reaction force of the master cylinder, and therefore the strength of the braking force. Can be sensed.

According to the second feature of the present invention, the master cylinder is configured in a tandem type in which a master piston is housed in the cylinder body and a master piston that partitions the interior into two chambers, a front brake hydraulic chamber and a rear brake hydraulic chamber. Then, the front end of the booster piston faces the brake hydraulic chamber and the reaction force fluid pressure chamber communicates. The inner piston is mechanically connected between the inner piston and the master piston only when the rear brake hydraulic chamber system fails. In addition, a reaction force mechanism that mechanically transmits a part of the operation reaction force of the master piston to the valve piston is provided, so even when the rear brake hydraulic chamber system fails, the inner piston and reaction mechanism are operated by the booster piston. The master piston can be mechanically pushed through the pressure to pressurize the front brake hydraulic chamber. In addition, since a part of the reaction force of the master piston at this time is transmitted to the valve piston via the reaction force mechanism, in this case also, the operator can accurately detect the strength of the braking force.

[Brief description of the drawings]

1 shows an embodiment of the present invention. FIG. 1 is a longitudinal side view of a hydraulic booster of the present invention connected to a tandem-type master cylinder, and FIG. 2 is an enlarged view of a main part of FIG. . B: fluid pressure booster, M: tandem type master cylinder 1 ... cylinder body, 5 ₁ ... front brake hydraulic chamber, 5 ₂ ... brake hydraulic chamber, 20 ... booster body, 27 ... booster piston, 29 …… Inner piston, 31… Valve piston, 39 …… Input rod, 45 …… Hydraulic pump as fluid pressure source, 47 …… Oil tank as fluid tank, 49 …… Input hydraulic pressure as input fluid pressure chamber Chamber, 52 ... Inlet port, 53 ... Outlet port, 60
…… Output hydraulic chamber as output hydraulic chamber, 61… Reaction hydraulic chamber as reaction hydraulic chamber

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yukitaka Miyagawa 1-4-1 Chuo, Wako-shi, Saitama Prefecture Inside Honda R & D Co., Ltd. (72) Kazuya Sakurai 1-4-1 Chuo, Wako-shi, Saitama Honda R & D Co., Ltd.

Claims (2)

(57) [Claims] 1. A booster body connected to a rear portion of a cylinder body of a master cylinder and having an input fluid pressure chamber and an output fluid pressure chamber connected to a fluid pressure source therein, and slidably fitted in the booster body. A front end facing the brake hydraulic chamber of the master cylinder, and a rear end facing the output fluid pressure chamber, and a booster piston facing the front end facing the braking hydraulic chamber and fitted to the booster piston. At the time of advance, it moves forward with it, but it is slidably fitted inside the inner piston which can move forward alone,
A valve piston for controlling the opening and closing of the flow path between the input and output fluid pressure chambers and the opening and closing of the flow path between the output fluid pressure chamber and the fluid tank by moving forward and backward with respect to the inner piston; A hydraulic pressure booster, wherein a reaction force hydraulic chamber facing the front end of the valve piston is provided in the inner piston in communication with the braking hydraulic chamber. 2. A tandem type engine according to claim 1, wherein the master cylinder houses a master piston in the cylinder body and a master piston partitioning the interior of the master cylinder into a front brake hydraulic chamber and a rear brake hydraulic chamber. With the front end of the booster piston facing the rear brake hydraulic chamber and communicating with the reaction force fluid pressure chamber, the inner piston is mechanically connected between the inner piston and master piston only when the rear brake hydraulic chamber system fails. A fluid pressure booster, further comprising a reaction mechanism for mechanically transmitting a part of the operation reaction force of the master piston to the valve piston.