JPS603003Y2 - brake booster - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a brake booster that uses gas pressure to boost brake operating force, and particularly relates to an improvement in a stroke expansion type booster.

Here, the stroke expansion type booster is a power piston that is arranged to divide the chamber in the booster casing into two, and is actuated by the pressure difference between the chambers on both sides.The power piston controls the pressure difference based on the operation of the input member. a valve mechanism that
The power piston is movable relative to a control piston having a relay mechanism that relays the operating force applied to the input member toward the output member, and is movable relative to the control piston by the forward motion of the power piston relative to the control piston. This is a type of booster designed to increase the stroke of the output member.

In a normal booster, the output stroke is always equal to or less than the input stroke, but this booster is characterized by an output stroke larger than the input stroke.

However, this stroke-expanding brake booster has a limit (hereinafter referred to as
When there is a limit point (called Daisuke limit yo), if you try to obtain an output higher than the output at the limit point, only the pedal stroke (input stroke) temporarily increases rapidly, but the brake force does not increase. There was a drawback that a phenomenon occurred.

In order to eliminate such problems, the present applicant has first created a structure that is simple and has no delay in operation, and even if there is variation in brake shoe clearance, the output stroke expansion action ends when the clearance disappears, and at the same time, the above-mentioned We have developed a brake booster equipped with a highly reliable power piston retreat prevention mechanism that prevents relative movement between the power piston and control piston (hereinafter referred to as lock).

This retreat prevention mechanism includes a ball and a ball retainer that holds the ball movably in the radial direction of the control piston between the power piston and the control piston. is approximately equal to the reaction force that acts on the pole retainer through the output member and the reaction lever when the brake clearance of the brake connected to the output member disappears and a braking action begins to occur between the brake and the piston. Apply a preload and install the spring,
When the brake clearance of the brake disappears, the spring is deformed and the ball is caught in the wedge-shaped gap formed between the power piston and the control piston, so that the It was constructed so that movement relative to the control piston was prevented.

However, although the balls in this brake booster are held in holes in the pawl retainer, a gap is required between the holes and the balls to allow movement of the balls in the radial direction of the control piston.

Therefore, when the output stroke expansion action ends when the clearance disappears and the power piston and control piston are locked together, an extra stroke of the power piston corresponding to the gap is required, and when the gap disappears, had the disadvantage of producing abnormal noise.

This invention was made against the background of the above circumstances,
The purpose of this is to create a brake structure that eliminates the gap between the ball and the hole in the pole retainer that holds it, thereby eliminating the stroke loss of the power piston during locking and preventing abnormal noise during its operation. The purpose is to provide a booster.

In order to achieve this object, the present invention provides the brake booster with an operating member movable in the axial direction relative to the control piston and the power piston, and the actuating member is connected to the first manual force part of the reaction lever. A ball is placed in contact with and behind the action member, and a ball drive mechanism including a spring that biases the ball toward the action member is provided between the ball and the power piston, and at the back of the ball. At least a part of the inner surface of the power piston is formed into an inclined surface, thereby forming a wedge-shaped gap that opens forward between the inclined surface and the outer surface of the control piston, and is connected to the output member. Until the brake clearance disappears, the output of the power piston is applied to the ball drive mechanism,
When the brake clearance disappears and the reaction force applied from the reaction lever to the action member increases, the spring is elastically deformed. The ball is caught in the wedge-shaped gap to prevent the power piston from moving forward relative to the control piston, so that the two pistons are integrated.

In this way, there will be no gap between the ball and the operating member that replaces the pole retainer, which will fundamentally solve the problem of stroke loss of the power piston during locking and abnormal locking noise. It will be resolved.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following, in order to further clarify the purpose, structure, and effects of the present invention, the present invention will be described in detail based on drawings showing embodiments thereof.

The booster 100 shown in FIG.
1 to the operating rod 1, which is an input member, and outputs it from the bushing rod 2, which is an output member, to the mask cylinder 102.

The booster 100 includes an airtight casing 3, and a chamber inside the casing 3 is partitioned by a diaphragm-type power piston 4.

The power piston 4 has a main body 49 and three screws 8 inside it.
1 and a howling member 41 held at the center thereof.

One of the chambers divided by the power piston 4 is connected via a pipe joint 5 to a vacuum source 103 such as an engine intake manifold or a vacuum pump, forming a constant pressure chamber 6 that is always under negative pressure.

The other chamber is selectively communicated with either the constant pressure chamber 6 or the atmosphere by a control valve to be described later, and serves as a variable pressure chamber 7 in which the internal pressure fluctuates.

A valve mechanism 20 and a relay mechanism 3 are located in the center of the power piston 4.
A control piston 9 equipped with 0 and 0 is slidably fitted together, and these constitute a control mechanism section 50.

The control piston 9 is separated from the main body 18 and a cylindrical member 17 fitted on the outside thereof.

The valve i structure 20 includes a first valve seat 21 formed on the control piston 9, a second valve seat 23 formed on the valve plunger 22 slidably fitted to the control piston 9, and both valve seats. The valve element 24 is made of an elastic material and is provided in common with the valve elements 21 and 23.

The valve element 24 is pressed against both valve seats 2 by a compression spring 26.
1 and 23 are biased towards each other.

Air flow passages 27 and 28 communicating with the constant pressure chamber 6 and the variable pressure chamber 7 are formed in the control piston 9 .

Further, a stopper 13 for regulating the forward and backward ends of the valve plunger 22 is inserted into a notch formed with a wider width and continuous with the flow path 28, and this stopper 13 is inserted at the rear of the casing 3. A stopper plate 11 that can come into contact with a wall and regulates the retreating end of the control piston 9
is fixed and prevented from being pulled out by a ring-shaped spring 12 held by a stopper plate 11.

A portion of the control piston body 18 protruding from the casing 3 is surrounded by a boot 15, and an air intake port 16 is formed at the end of the boot 15.

On the other hand, the intermediate tilting mechanism 30 includes the valve plunger 22, a large plunger 32 fitted to the control piston 9, and a rubber reaction disk 33 interposed between the two.

This reaction disk 33 is connected to the valve plunger 2.
2 and the control piston 9, the large plunger 3
2.

The large plunger 32 has a rod portion 3 that protrudes forward from the center.
4, and a rod portion 34 supports the rear end portion of the bush rod 2.

As shown in FIG. 1, a circumferential gap 42 is formed between the power piston 4 and the control piston 9.
Here, the hole retainer 43, which is the operating member that rotatably holds a plurality (three) of balls 44, and a compression spring 84.
and a spring retainer 89 are housed therein.

That is, as shown in FIG. 2, the outer peripheral surface of the cylindrical member 17 has a groove-shaped tapered portion whose depth gradually increases as it moves forward (to the left in the figure) (approaching the axis of the control piston 9). A ball accommodating recess 61 having a diameter of 66 is formed.

On the other hand, in the inner circumferential surface of the front half of the annular member 41, there is a groove opposite to the ball accommodation recess 61, and at the bottom thereof there is a flat part 62 parallel to the axis of the power piston 4, and a flat part 62 parallel to the axis of the power piston 4; A steeply sloped portion 64 that is sloped in a direction approaching , and a gently sloped portion 65 that is gentler than the steeply sloped portion are sequentially formed from the front end.

This gently inclined portion 65 functions together with the tapered portion 66 as a tank surface.

63 is a small diameter portion. As is clear from FIG. 2, the ball retainer 43 has a cylindrical portion 46 with a semicircular notch at its rear end for supporting the balls, and a flange-shaped portion formed at a right angle outward at its front end. It consists of a contact part 47.

The brim-shaped contact portion 47 is provided with three openings 80 to prevent the front end of the annular member 41 from coming into contact with the power piston 4 when the power piston 4 moves forward relative to the control piston 9. As shown in FIG. 1, at a symmetrical position of the opening 80 with respect to the center line, there is a lever retainer part 83, which is a pair of holding pieces with a part of the abutment part bent up, in order to position and hold the reaction lever 51. There are three locations.

A coiled compression spring 84 is installed coaxially between the spring retainer 89 and the annular member 41, and forms a ball drive mechanism together with the spring retainer 89.

Therefore, the balls 44 located in front of the spring retainer 89 are always brought into contact with the cylindrical portion 46 of the ball retainer without any gap, and the ball 44 is placed in front of the spring retainer 89.
3 is always urged forward, but the annular metal fitting 82
Advancement is prevented by inverted-shaped stopper portions 85 provided toward the center from the three threaded portions of the power piston body 49 and the power piston body 49.

Furthermore, three inverted U-shaped holding parts 86 having openings and notched ends for positioning and holding the spring receiver 56 are integrally provided at axially symmetrical positions of the threaded part of the annular metal fitting 82. .

Between the abutment part 47, the large plunger 32, and the reaction plate part 8 at the rear end of the bushing rod, there are three K-shaped plates, one end of which is engaged with the lever retainer part 83 and prevented from being pulled out with a split pin. A shaped reaction lever 51 is interposed and held in position.

The cylindrical member 17 has three flange portions 54 at its front end.
have.

One end is brought into contact with this flange part, the other end is fitted into an opening formed in the holding part 86, and the three parts are engaged with a notch formed at the tip of the holding part 86. The middle part of the spring receiver 56 and the casing 3
A coiled compression spring 5 is connected between the front wall and the opposite front wall.
7 is arranged coaxially with the casing 3.

Next, the operation of this embodiment will be explained.

When the brake pedal 101 is not depressed, the second valve seat 23 contacts the valve element 24 and the first valve seat 21 is separated, so the variable pressure chamber 7 communicates with the constant pressure chamber 6 and the two chambers are equal. It is maintained at negative pressure and the power piston 4
There is no pressure difference on either side.

For this purpose, the power piston 4 and the control piston 9 are compressed by a compression spring 5 applied via a spring receiver 56.
7, the control piston 9 is held in the retracted position via the stopper plate 11 and the power piston 4 is held in direct contact with the casing 3.

FIG. 1 shows this situation.

In this state, when the brake pedal 101 is slightly depressed and the operating rod 1 is moved forward (moved to the left in FIG. 1), the first valve seat 21 contacts the valve element 24 and then the second valve seat 23 Separate from this, the variable pressure chamber 7 is separated from the constant pressure chamber 6 and communicates with the atmosphere.

As a result, a pressure difference is created between the variable pressure chamber 7 into which air flows and the constant pressure chamber 6, and the power piston 4 is moved forward by the force based on this difference.

When the power piston 4 moves forward, before force is directly applied to the ball 44 by the steeply inclined portion 64 of the annular member 41, the ball 4 is moved forward by a ball drive mechanism consisting of a compression spring 84 and a spring retainer 89, thereby causing the ball 4 to move forward. Retainer 43 is advanced.

As the pole retainer 43 moves forward, a force is applied to the first manual force part 71 of the reaction lever 51 as shown in FIG. It can be rotated using the output section 75 as a fulcrum.

As a result, thrust is applied to the bushing rod 2 from the intermediate output section 72 through the reaction plate section 8.

As a result, the brake fluid in the mask cylinder 102 is supplied to a brake system (not shown), the brake clearance is eliminated, and the amount of fluid consumed due to the initial deformation of the piston cup etc. is filled.

In other words, an output stroke that is much larger than the input stroke is obtained.

By the time the brake shoe clearance disappears and the reaction force of the brake begins to appear on the bushing rod 2 via the mask cylinder, it is transferred to the pole retainer 4 through the transmission path opposite to the above.
3's advance is stopped.

That is, the preload of the compression spring 84 is selected to be equal to the reaction force at this time.

Even if the forward movement of the pole retainer 43 and the ball 44 is stopped, the power piston 4 moves forward against the elastic force of the compression spring 84, so that the power piston 4 moves forward as shown in FIG.
The gently sloping part 65 rides on the stopped ball 44,
The ball 44 is caught in a wedge-shaped gap between the gently inclined portion 65 and the tapered portion 66 of the control piston 9.

This causes the power piston 4 to become the control piston 9.
The tapered portion 66 and the gently sloped portion 65 serve as locking surfaces, and the ball 44 and the pole retainer 43 also become immovable relative to the ball 44 and the pole retainer 43 either forward or backward. .

In the brake booster between starters shown in FIG.
A gap A exists to allow movement of the control piston 4 in the radial direction, and the power piston 4 must further advance a stroke corresponding to the gap A until it reaches the locked state.

However, according to this example, the pole retainer 43 and the ball 4
4 are always in contact with each other by the compression spring 84, and there is no gap between them, so when locking, the stroke loss of the power piston 4 and the sound of the gap disappearing can be fundamentally eliminated.

As is clear from the above description, the accommodation recess 61 only needs to have the tapered part 66 of the shape described above, and the curved surface 67 on the front side can be eliminated, but if this is used, the stopper This eliminates the need for the flange portion 54.

After the pawl retainer 43 becomes immovable relative to the control piston 4 and the gently inclined portion 65 of the power piston 4 comes into contact with the ball 44 held by the pawl retainer 43, the operating rod 1 is moved as in a conventional brake booster. and the power piston 4 are the reaction lever 5
1 and the reaction disk 33, the bushing rod 2 is moved forward.

After the power piston 4 is advanced in this manner until the pressure difference between its two sides reaches its limit, the brake pedal 1
When 01 is pressed even harder, reaction lever 5
The output part 75 of the large plunger 32 is attached to the second human power part 74 of 1.
A strong force is applied to the reaction lever 51, and the reaction lever 51 rotates with the reaction plate portion 8 against which the output portion 72 is brought into contact, pushing the pole retainer 43 back.

I try to sleep.

At this time, the ball retainer 43 does not retreat at all.

This is because the portion closer to the rear than the center of the ball is brought into contact with the tapered portion 66 of the accommodation recess and the gently sloped portion 65 whose spacing gradually decreases.

Therefore, no idle stroke occurs in the brake pedal.

Moreover, the forward end of the valve plunger 22 is connected to the stopper 13.
As a result, the operating rod 1, valve plunger 22, control piston 9, large plunger 32, and reaction disc 33
, the pole retainer 43, the rear axle control lever 51, etc. are in an integrated state, and the bushing rod 2 is pushed out through the action plate portion 8 by this integration.

The output stroke therefore increases at the same rate as the input stroke.

However, at this time, since the assisting force to the power piston 4 has reached its limit, the output of the booster increases only by the increase in the brake operating force.

When the brake pedal 101 is released, the valve element 24 contacts the second valve seat 23 and the first valve seat 21
The variable pressure chamber 7 is isolated from the atmosphere and communicated with the constant pressure chamber 6 (see Figure 1), and the power piston 4
The supporting force will no longer work on .

As a result, the power piston 4, control piston 9, etc., which are integrally locked by the urging force of the spring 57 applied via the spring receiver 56, are moved backward.

This retreat causes the stopper plate 11 to move toward the casing 3.
When the control piston 9 comes into contact with the control piston 9, the retraction of the control piston 9 is stopped, and then the power piston 4 is retracted with respect to the control piston 9.

At this point, the brake reaction force applied to the pawl retainer 43 is reduced and the force for locking the power piston 4 and control piston 9 is also reduced, so the power piston 4 can move backward relative to the control piston.

As a result, the unlocked balls 44 and the pawl retainer 43 are moved forward by the elastic force of the compression spring until the pawl retainer 43 abuts against the stopper portion 85.

The power piston 4 moves backward until it comes into contact with the casing 3, and the operation ends.

It should be noted that what has been described in detail above is only one embodiment of the present invention, and the present invention should not be interpreted as being limited thereto.

For example, the structure in which the balls 44 are brought into constant contact with the pole retainer 43 is not limited to the structure shown in FIG. 6, but may be modified in various ways.

In FIG. 6, spring retainer 89 is removed;
The structure is such that the compression spring 84 directly urges the pole 44 forward.

Further, the inclination angle (α) of the tapered portion 66 of the accommodation recess with respect to the control piston center line is oo<α≦15°, and the inclination angle (β) of the steeply inclined portion 64 with respect to the control piston center line is 20°≦β≦75°. , gentle slope part 65
The inclination angle (γ) of can be appropriately selected within the range of o'<γ≦30'.

Further, regarding the tapered portion 66, the inclination angle of the portion closer to the front can be made larger than that of the portion closer to the rear within a range of 15° or less.

On the other hand, regarding the steeply sloped portion 64 and the gently sloped portion 65, the point is that the inclination angle of the rearward portion should be gentler than the other portions. It is also possible to eliminate the corners and make the entire surface a curved surface.

Furthermore, the control piston 9 and the valve plunger 22
Although the reaction disk 33 is suitable as a medium for transmitting the resultant force of both to the large plunger portion 32 while allowing relative movement between the two, a lever or the like may be used instead. No. 4.100.83
As shown by the peak, the valve plunger 22 and the large plunger 32 may be integrated.

Further, the assisting force to the power piston may be generated by a pressure difference between atmospheric pressure and positive pressure, or it may be set to constant atmospheric pressure as shown in U.S. Patent No. 3.110.031. The auxiliary force may be obtained by a pressure difference between a chamber that is set to atmospheric pressure or a chamber that is selectively set to atmospheric pressure or negative pressure.

Furthermore, as shown in Japanese Patent Application Laid-Open No. 54-99875, the present invention is also applicable to a stroke-expanding brake booster in which a compression spring is disposed between a power piston and a control piston.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a brake booster according to an embodiment of the present invention. FIG. 2 is an enlarged view of the main part of the embodiment shown in FIG. 1. 3 and 4 are explanatory views of the operation of the embodiment shown in FIGS. 1 and 2. FIG. FIG. 5 is an explanatory diagram of the operation of the brake booster of the previous invention. FIG. 6 is an enlarged view of main parts of another embodiment of the present invention. 1: Operating rod (input member), 2: Push rod (output member), 3: Casing, 4: Power piston, 9: Control piston, 20: Control valve (valve mechanism), 30: Relay mechanism, 43: Ball retainer (Action member), 44: Ball, 51: Reaction lever, 65: Gently inclined part (slanted surface), 71: First human power part, 72: Second human power part, 84 Ni spring, 100 Ni brake booster.

Claims (1)

[Claims for Utility Model Registration] A power piston that is arranged to divide a chamber inside the casing into two and is actuated by the pressure difference between the two chambers is connected to a valve mechanism and input for controlling the pressure difference between the two chambers. A control piston having a built-in relay mechanism that transmits the input of the member to the output member is fitted to the outer circumferential surface of the control piston so as to be relatively movable in the axial direction, and the output of the power piston and the output of the relay mechanism are connected to each other, A stroke larger than that of the input member is inputted to a first manual power part and a second manual power part located on both sides of the output part of the reaction lever that is brought into contact with the output member at the intermediate output part, and is applied to the output member with a stroke larger than that of the input member. In the brake booster configured to obtain the above, an operating member movable in the axial direction relative to the control piston and the power piston is provided, and this is brought into contact with the first manual force portion of the reaction lever, and the A ball is disposed behind the action member, and a ball drive mechanism including a spring that biases the ball toward the action member is provided between the ball and the power piston, and at least the power is provided behind the ball. By forming a part of the inner surface of the piston into an inclined surface, a wedge-shaped gap which opens toward the front is created between the inclined surface and the outer surface of the control piston, thereby increasing the clearance of the brake connected to the output member. Until the brake clearance disappears, the output of the power piston is transmitted to the first manual force part of the reaction lever via the ball drive mechanism, the ball, and the action member, and the brake clearance disappears and the output is applied from the reaction lever to the action member. When the reaction force increases, the spring is elastically deformed, the ball is caught in the wedge-shaped gap, and the power piston is prevented from moving forward relative to the control piston, so that both pistons are integrated. A brake booster characterized in that it is configured to