JP3684598B2 - Negative pressure booster - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a negative pressure booster, and more particularly to a mounting structure for a rear shell of a negative pressure booster.
[0002]
[Prior art]
As this type of prior art, one disclosed in Japanese Utility Model Publication No. 6-35848 is known. The negative pressure booster disclosed in this publication is incorporated in a housing formed of a front shell and a rear shell, a power piston that divides the housing into at least one set of variable pressure chamber and constant pressure chamber, and a power piston. A valve mechanism that controls the differential pressure between the variable pressure chamber and the constant pressure chamber in conjunction with the input rod, an output rod that transmits the operating force applied to the input rod with the assistance of the power piston, and a key that defines the position of the valve mechanism And a holding member for fixing a rear shell disposed in close contact with the sealing member, and holding the inner peripheral end of the rear shell. For attachment to the end of the member, the inner peripheral end of the rear shell is bent so as to cover the key member, and the inner peripheral end of the rear shell and the end of the holding member are fixed. It is intended.
[0003]
[Problems to be solved by the invention]
In general, in order to reduce the width of the housing, the constant pressure chamber and the valve mechanism require a certain width, and therefore there is a limit to reducing the width. For this reason, in the above-described prior art, the key member that defines the position of the valve mechanism can be moved rearward to reduce the housing width by the amount of movement. In addition, in order to move the key member, the fixing position of the rear shell and the holding member also moves, and in order to fix the key member so as to cover the key member with the housing width reduced, the inner peripheral end of the rear shell is axially It was necessary to extend to. However, the manufacturing process for bending the inner peripheral end of the rear shell in the axial direction is complicated and the cost increases. Further, when the key member is changed, it is necessary to recreate the rear shell, so that the cost is high and the versatility is poor.
[0004]
It is an object of the present invention to reduce the manufacturing process related to the rear shell and to easily cope with the change of the key member.
[0005]
[Means for Solving the Problems]
Means taken in the present invention to solve the above-described problems are a housing formed of a front shell and a rear shell, a power piston that divides the housing into at least one set of a variable pressure chamber and a constant pressure chamber, A valve mechanism that is incorporated in the power piston and controls the differential pressure between the variable pressure chamber and the constant pressure chamber in conjunction with the input rod; and an output rod in which an operating force applied to the input rod is assisted by the power piston and transmitted. A negative pressure type comprising a key member for defining the position of the valve mechanism, a holding member to which an inner peripheral end of the rear shell bent in the axial direction is fixed, and a seal member in close contact with one end of the holding member In the booster, the other end of the holding member extends in the axial direction, the end thereof is bent in the circumferential direction, and the inner periphery of the rear shell is connected to the end. There are fixed, it is that the key member is arranged to be positioned in and out of the housing so as to be covered with the holding member.
[0006]
[Action]
According to the above means, when an operating force is applied to the input rod, the input rod operates the valve mechanism, a pressure difference is generated between the variable pressure chamber and the constant pressure chamber, the power piston starts to move, and the output It is transmitted to the rod. In order to reduce the housing width, the key member is disposed outside the housing, but the holding member for fixing the rear shell extends in the axial direction so as to cover the key member. The part is bent in the outer circumferential direction. The inner peripheral end of the rear shell bent in the axial direction is fixed to the holding member by press fitting or the like. This eliminates the need to bend the inner peripheral end of the rear shell so as to cover the key member. Moreover, when the position of the key member is changed, it can be easily handled by changing the holding member without changing the rear shell, the manufacturing process of the rear shell can be reduced, and the cost can be reduced. it can.
[0007]
【Example】
An embodiment of the present invention will be described with reference to the drawings.
[0008]
FIG. 1 shows an example in which the present invention is implemented in a single type negative pressure booster. As shown in the drawing, the housing 11 of the negative pressure type booster 10 includes a cup-shaped front shell 12 attached to a master cylinder (not shown) in the front (left side in the drawing), and an airtight at the rear end of the front shell 12. The plate-shaped rear shell 13 is attached to the vehicle body (not shown) at the rear and is internally divided into a set of constant pressure chambers 15 and a variable pressure chamber 16 by a power piston 14. A bolt 17 for attaching the master cylinder and a connector 18 connected to an intake manifold (not shown) of the engine are airtightly attached to the front shell 12, and a negative pressure booster is attached to the rear shell 13. Bolts 19 for attaching to the vehicle body are airtightly attached.
[0009]
The power piston 14 includes a resin hub member 20, an annular plate 21, and a diaphragm 22. The hub member 20 has a cylindrical portion 20a that protrudes out of the housing 11 through the seal member 23, and a valve mechanism 30 is incorporated therein. The plate 21 is airtightly fitted to the step portion of the hub member 20 together with the inner peripheral bead portion 22 a of the diaphragm 22. The diaphragm 22 is provided on the rear surface of the plate 21, and an outer peripheral bead portion 22 b is hermetically fitted between the step portion of the rear shell 13 and the rear end portion of the front shell 12.
[0010]
The valve mechanism 30 is for communicating the variable pressure chamber 16 with the constant pressure chamber 15 or the atmosphere, and includes a valve plunger 31, a control valve 32, and the like. The valve plunger 31 is fitted into the hub member 20 so as to be slidable in the axial direction in a state where the valve plunger 31 is assembled to the tip of the input rod 40 interlocked with a brake pedal (not shown), and is stopped by the key member 41. The control valve 32 is assembled in the cylindrical portion 20a of the hub member 20 behind the valve plunger 31 and is urged forward by a spring 33, and the valve plunger 31 is moved in accordance with the axial movement of the input rod 40. It selectively engages with the rear end surface or the inner hole step portion 20 b of the hub member 20.
[0011]
In the valve mechanism 30, when the control valve 32 is engaged with the rear end surface of the valve plunger 31 and is separated from the inner hole step portion 20 b (at the time of operation return), the through holes provided in the cylindrical portion 20 a and the hub member 20. The constant pressure chamber 15 and the variable pressure chamber 16 communicate with each other by 20c. Further, when the control valve 32 is engaged with the inner hole step portion 20b and is separated from the rear end surface of the valve plunger 31 (at the time of operation), the through hole 20c of the hub member 20, the inside of the cylinder portion 20a, the control valve 32, and the like. The variable pressure chamber 16 communicates with the atmosphere (outside air) through the inner hole, the air filter 50, and the vent hole 42a of the boot 42 provided between the housing 11 and the input rod 40.
[0012]
An output rod 44 is assembled with a rubber reaction disc 43 at the front end of the power piston 14. The output rod 44 is engaged with a piston of a master cylinder (not shown), and a reaction disk 43 is accommodated in the rear end cylinder portion. A spring 45 is engaged with the front surface of the power piston 14, and the power piston 14 is urged rearward (rightward in the drawing) by the spring 45.
[0013]
In the present invention, the seal member 23 is in close contact with the rear surfaces of both end portions of the key member 41, and the holding member 24 interposed between the boot 42 and the seal member 23 is above and below the key member 41. Is arranged so as to cover. As described above, one end of the holding member 24 is interposed between the seal member 23 and the boot 42, the other end extends in the axial direction so as to cover the key member 41, and the end portion is folded in the circumferential direction. It is tuned. The inner peripheral end of the rear shell 13 bent in the axial direction is fixed to the bent end portion by press-fitting.
[0014]
Next, the operation of this embodiment will be described.
[0015]
First, in a non-operating state, the rear end surface of the valve plunger 31 is in contact with the control valve 32, and the air that has passed through the air filter 50 is blocked by the control valve 32. Further, the valve plunger 31 is pushed rightward in the drawing until the key member 41 contacts the hub member 20 by the spring 45, and pushes the control valve 32 rightward. As a result, the inner hole stepped portion 20b and the control valve 32 are separated from each other, the through hole 20c and the cylindrical portion 20a communicate with each other, and the constant pressure chamber 15 and the variable pressure chamber 16 communicate.
[0016]
In the operating state, when a brake pedal (not shown) is stepped on, the input rod 40 moves leftward while pushing the valve plunger 31, and the control valve 32 also moves leftward simultaneously. Thereafter, when the control valve 32 comes into contact with the inner hole step portion 20b, the communication between the constant pressure chamber 15 and the variable pressure chamber 16 is blocked. Further, when the valve plunger 31 advances leftward, the rear end surface of the valve plunger 31 and the control valve 32 are separated, and the air flows into the variable pressure chamber 16 through the through hole 20c. As a result, the degree of negative pressure in the variable pressure chamber 16 decreases, a pressure difference is generated between the constant pressure chamber 15 and the power piston 14 starts to move to the left. The force generated in the power piston 14 by this differential pressure is transmitted to the output rod 44 via the reaction disk 43.
[0017]
As described above, it is not necessary to bend the inner peripheral end of the rear shell 13 so that the key member 41 covers it. Further, when the position of the key member 41 is changed, it is not necessary to change the rear shell 13, and it can be easily dealt with by changing the holding member 24, and the manufacturing process of the rear shell 13 can be reduced.
[0018]
【The invention's effect】
According to the negative pressure type booster of the above-described invention, the holding member for fixing the rear shell extends in the axial direction so as to cover the key member, and the end portion is bent in the outer peripheral direction.
[0019]
The inner peripheral end of the rear shell bent in the axial direction is fixed to the holding member by press fitting or the like. This eliminates the need to bend the inner peripheral end of the rear shell so as to cover the key member. Moreover, when the position of the key member is changed, it can be easily handled by changing the holding member without changing the rear shell, the manufacturing process of the rear shell can be reduced, and the cost can be reduced. it can.
[Brief description of the drawings]
FIG. 1 is a sectional view of a negative pressure booster according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Housing 12 ... Front shell 13 ... Rear shell 14 ... Power piston 15 ... Constant pressure chamber 16 ... Transformer chamber 20a ... Cylindrical part 23 ... Seal member 24 ... Holding member 30 ... Valve mechanism 40 ... Input rod 41 ... Key member 44 ... Output rod

Claims (1)

A housing formed of a front shell and a rear shell; a power piston that divides the housing into at least one set of a variable pressure chamber and a constant pressure chamber; and the variable pressure chamber that is incorporated in the power piston and interlocks with an input rod; A valve mechanism for controlling a differential pressure with respect to the constant pressure chamber, an output rod to which an operating force applied to the input rod is transmitted by being assisted by the power piston, a key member for defining the position of the valve mechanism, and an axial direction In a negative pressure type booster comprising a holding member to which the inner peripheral end of the bent rear shell is fixed and a seal member in close contact with one end of the holding member, the other end of the holding member extends in the axial direction. And the end of the rear shell is bent in the circumferential direction, and the inner peripheral end of the rear shell is fixed to the end, so that the key member is covered with the holding member. One said vacuum booster, characterized in that it is arranged so as to be located outside the housing.

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