JP2006088887A - Pneumatic booster - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic booster capable of achieving a long stroke without causing increase of pedal stepping force. <P>SOLUTION: In starting boosting action, a vacuum valve 11A is closed, and a negative pressure passage 71 is disconnected from a valve element back surface side space 70A to be set in a negative pressure state. As an input rod 7 advances to open an atmospheric air valve 10, atmospheric air is introduced to a pressure changing chamber 4 to thrust a power piston 5, while atmospheric air is introduced to the poppet valve element back surface side space 70A, so that a valve element separating and seating part 57 of a poppet valve element 12A receives pressure on the side of the negative pressure passage in a negative pressure state in such a direction as to close a valve seat 73 for negative pressure. Spring force, or ineffective input, necessary for maintaining a vacuum valve 11A closed when the atmospheric air valve 10 is opened can be reduced. Therefore, pedal stepping force need not be increased even when a pedal ratio is lowered as required following achievement of the long stroke. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pneumatic booster used in a vehicle brake system.

  An example of a pneumatic booster is shown in FIG. 4 (see Patent Document 1). The pneumatic booster 1 shown in FIG. 4 is arranged in a power piston 5 that divides the inside of the shell body 2 into a constant pressure chamber 3 and a variable pressure chamber 4, and a tubular portion 39 of a valve body 6 connected to the power piston 5. And a valve mechanism 9 that operates in conjunction with a plunger 8 connected to the input rod 7. The tubular portion 39 is inserted through the shell body 2 and extends rearward.

  The valve mechanism 9 includes an atmospheric valve 10 and a vacuum valve 11, and has a poppet valve body 12 that constitutes a part of each of the atmospheric valve 10 and the vacuum valve 11. The atmospheric valve 10 communicates / blocks the variable pressure chamber 4 and the atmosphere, and the vacuum valve 11 communicates / blocks the constant pressure chamber 3 and the variable pressure chamber 4. The poppet valve body 12 includes a substantially cylindrical poppet valve body base end portion 12a fixed to the valve body 6, a substantially cylindrical bellows portion 12b connected to the poppet valve body base end portion 12a, and a bellows portion 12b. And an annular valve body seat 12c that is connected to the distal end side and seats on an atmospheric valve seat 20 and a negative pressure valve seat 23 described later. And the front end side of the bellows part 12b is connected with the outer diameter side part of the valve body attaching / detaching seat part 12c.

In addition, a rear region (hereinafter referred to as a tubular portion space rear region) 37 a of the atmospheric valve 39 in the internal space (cylindrical portion space) 37 of the tubular portion 39 is brought into the atmosphere through the opening of the tubular portion 39. Communicate.
A valve spring 15 is interposed between the input rod 7 and the valve body 6, and a poppet spring 16 is interposed between the input rod 7 and the tip of the poppet valve body 12.

  The valve spring 15 presses the input rod 7 against the valve body 6 against the base end side (right side in FIG. 4). The poppet spring 16 presses the tip of the poppet valve body 12 against the plunger 8 (and eventually the valve seat 20 for the atmosphere). The vacuum valve 11 is arranged with the central axis thereof identical to the central axis of the atmospheric valve 10 (that is, coaxially arranged with the atmospheric valve 10) and is disposed outside the atmospheric valve 10 (that is, vacuum). The diameter of the valve 11 is larger than that of the atmospheric valve 10).

In the pneumatic booster 1, when a brake pedal (not shown) connected to the input rod 7 is depressed, the input rod 7 moves forward against the spring force of the valve spring 15 and the like. The forward movement of the rod 7 opens the atmospheric valve 10 so that the cylindrical part space rear region 37 a and the variable pressure chamber 4 communicate with each other, and the atmospheric pressure is introduced into the variable pressure chamber 4. By introducing air into the variable pressure chamber 4, a pressure difference is generated between the constant pressure chamber 3 and the variable pressure chamber 4, and thrust generated in the power piston 5 due to this pressure difference is applied to the output rod 22 via the reaction disk 21. At the same time, a part of the reaction force acting on the reaction disk 21 from the output rod 22 is transmitted to the input rod 7.
As the input rod 7 advances and the power piston 5 (valve body 6) advances, the valve body 6 advances by a predetermined amount relative to the input rod 7, thereby closing the atmospheric valve 10. It becomes a balance state.

  When the pedaling force on the brake pedal is released, the input rod 7 is retracted by the spring force of the valve spring 15 and the plunger 8 is also retracted. As a result, the poppet valve body 12 is pushed by the plunger 8 and the valve seat (hereinafter referred to as negative pressure valve seat) 23 of the vacuum valve 11 provided inside the valve body 6 is opened. A negative pressure is introduced through the passage 24 and the atmospheric passage 25, and the pressure difference described above is eliminated. Thereafter, the valve body 6 is retracted by the spring force of the return spring 26 in the constant pressure chamber 3, and the stop key 27 inserted in the radial hole 27 a formed in the valve body 6 contacts the stepped surface 29 in the rear shell 28. The power piston 5 returns to the original position, and at the same time, the plunger 8 also returns to the original position, and the vacuum valve 11 is also closed.

  The negative pressure passage 24 is formed in the valve body 6 with one end side communicating with the constant pressure chamber 3 and the other end opening on the inner peripheral surface of the cylindrical portion 39. An opening (hereinafter referred to as a negative pressure passage opening) 24 a on the other end side of the negative pressure passage 24 is disposed facing the outer peripheral side of the poppet valve body 12. An edge of the negative pressure passage opening 24 a in the reaction disk 21 side direction is a negative pressure valve seat 23 of the vacuum valve 11, and an outer peripheral side portion of the valve body seating part 12 c is separated from the negative pressure valve seat 23. Sit down. A space 70 formed by the tubular portion 39 and the poppet valve body 12 (hereinafter referred to as a poppet valve body outer circumferential side space) 70 has a negative pressure when the valve body seating portion 12c is seated on the negative pressure valve seat 23. It communicates with the passage 24.

As described above, when the atmospheric valve 10 is opened by the advancement of the input rod 7, it is determined by the set load (spring force) of the valve spring 15 or the like, and is a force required to open the atmospheric valve 10 (hereinafter referred to as invalid input). ) When the above force is applied to the input rod 7, the atmospheric valve 10 is opened. Further, the set load (spring force) of the valve spring 15 and the poppet spring 16 resists the pressure difference between the internal pressure of the constant pressure chamber 3 in the negative pressure state or the variable pressure chamber 4 into which the negative pressure is introduced and the atmosphere. It is set up.
JP 2004-001632 A

  By the way, recently, in a pneumatic booster, it is desired to achieve a longer stroke in accordance with a longer stroke of a master cylinder used therewith. When a long stroke is achieved for the pneumatic booster, it is necessary to lower the pedal ratio (to reduce the pedal ratio) in order to maintain a good relationship between the stroke with respect to the master cylinder and the pedal operation amount.

However, when the pedal ratio is reduced, the pressure booster having the conventional structure increases the initial pedal effort (and consequently increases the invalid input), and the pedal operability is deteriorated accordingly, which is inconvenient. In order to improve the pedal operability that deteriorates in this way, it is conceivable to reduce the invalid input. However, most of the invalid inputs are valve springs and poppets that are set to resist the pressure difference between the internal pressure of the constant pressure chamber in the negative pressure state or the variable pressure chamber into which the negative pressure is introduced as described above and the atmosphere. It is the set load (spring force) of the spring, and it was not easy to reduce it appropriately.
For this reason, the actual situation is that a low pedal ratio, that is, a long stroke cannot be properly achieved.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pneumatic booster that can achieve a long stroke without causing an increase in pedal effort.

  The invention according to claim 1 divides the inside of the shell body into a constant pressure chamber and a variable pressure chamber by a power piston, and extends the tubular portion of the valve body connected to the power piston to the rear thereof through the shell body, A valve mechanism linked to a plunger connected to an input rod is disposed in the valve body, and one end side of the valve body communicates with the constant pressure chamber, and the other end side has a negative pressure on the inner peripheral surface of the cylindrical portion. A negative pressure passage that opens as a passage opening is provided, and the valve mechanism is operated as the input rod moves forward, and the atmosphere is introduced into the variable pressure chamber through the opening of the cylindrical portion, thereby the constant pressure chamber and the variable pressure chamber. A pressure booster that generates a pressure difference with the chamber and propels the power piston by this pressure difference, wherein the negative pressure passage opening opens toward the proximal end of the input rod. The valve mechanism is An annular atmospheric valve seat formed at the rear end of the plunger, a negative pressure valve seat formed at a peripheral edge of the negative pressure passage opening, the atmospheric valve seat and the negative pressure valve seat A poppet valve body disposed so as to be separable, and the poppet valve body opens and closes the negative pressure passage opening by facing the negative pressure valve seat and faces the negative pressure passage opening. The poppet valve body back side space surrounded by the tubular portion and the poppet valve body in the back region of the poppet valve body communicates with the variable pressure chamber.

According to a second aspect of the present invention, in the pneumatic booster according to the first aspect, the poppet valve body is fixed to the tubular portion of the valve body via a tubular body provided inside the tubular portion. A substantially cylindrical poppet valve body base end portion, a substantially cylindrical bellows portion connected to the poppet valve body base end portion, and connected to a distal end side of the bellows portion to connect the atmospheric valve seat and the negative valve seat An annular valve body seat for seating on and off from the pressure valve seat; and a poppet spring that presses the valve body seat on the air valve seat and the negative pressure valve seat in the direction of seating. The connection of the front end side to the valve body seating part is performed at the inner diameter side portion of the valve body seating part.
According to a third aspect of the present invention, in the pneumatic booster according to the first or second aspect, the poppet spring is interposed between the valve body seating portion and the cylindrical portion.

  According to the first aspect of the invention, when the boosting action is started, the negative pressure passage is in a negative pressure state and is blocked from the space behind the poppet valve body, and the atmospheric valve is opened by the advancement of the input rod. When the valve is operated, the atmosphere is introduced into the variable pressure chamber and a pressure difference is generated between the constant pressure chamber and the variable pressure chamber, and the power piston is propelled. On the other hand, the air is introduced into the space behind the poppet valve body. Is pressed in the direction of closing the negative pressure passage side, that is, the negative pressure valve seat. For this reason, when the atmospheric valve is opened, the spring force required to maintain the vacuum valve in the closed state can be reduced correspondingly, and the invalid input can be reduced accordingly. Since the invalid input can be reduced in this way, it is not necessary to increase the pedal effort even when the pedal ratio is reduced as required along with the longer stroke. In other words, it is possible to achieve a long stroke (and consequently a low pedal ratio) without increasing the pedal effort.

According to the second aspect of the present invention, since the connection to the valve body seating portion on the tip side of the bellows portion is performed at the inner diameter side portion of the valve body seating portion, the space on the back surface of the poppet valve body is widened. It is possible to secure a space for disposing the poppet spring in the space behind the poppet valve body.
According to the third aspect of the present invention, the poppet spring is interposed between the valve body separating seat and the tubular body, and the spring force of the poppet spring acts as a pressing force against the negative pressure valve seat. It will have a reliable sealing property. In addition, since the poppet spring does not pass through when the atmosphere is introduced into the variable pressure chamber, air communication noise can be reduced.

Hereinafter, a pneumatic booster 1A according to a first embodiment of the present invention will be described with reference to FIGS.
1 and 2, the pneumatic booster 1 </ b> A includes a shell body 2 including a front shell 30 and a rear shell 28, and the inside of the shell body 2 is divided into a constant pressure chamber 3 and a variable pressure chamber 4. A partitioning power piston 5 is provided. The power piston 5 is held by a diaphragm 35, and a valve body 6 in which a shaft hole 36 and a cylindrical portion space 37 are formed is provided at the center thereof.

  The valve body 6 is formed with a large-diameter main body (hereinafter referred to as a valve body main body) 38 in which a shaft hole 36 and a part of the cylindrical part space 37 are formed, and a large part of the cylindrical part space 37. The cylindrical portion 39 is connected to a small-diameter cylindrical portion 39, and the cylindrical portion 39 is inserted into the small-diameter cylindrical portion 40 at the rear of the rear shell 28 in an airtight and slidable manner and extends to the rear thereof. ing. The cylindrical portion 39 includes a cylindrical portion distal end side portion 39A on the side of the opening (hereinafter referred to as a cylindrical portion opening portion) 39a, and a cylindrical portion distal end side portion 39A on the side opposite to the cylindrical portion opening 39a. And a cylindrical portion proximal end portion 39B. The tubular portion proximal end portion 39B is connected to the valve body main body portion 38. Further, the tubular portion proximal end portion 39B has a thickness dimension larger than that of the tubular portion distal end side portion 39A.

The valve body 6 is provided with a negative pressure passage 71 (constant pressure passage) whose one end communicates with the constant pressure chamber 3 and whose other end opens on the inner peripheral surface of the cylindrical portion 39. An opening (hereinafter referred to as a negative pressure passage opening) 72 on the other end side of the negative pressure passage 71 protrudes in a substantially cylindrical shape from the tubular portion proximal end portion 39B toward the tubular portion distal end portion 39A. It opens toward the base end side of the input rod 7 (rightward in FIG. 2 and in front of FIG. 3), and is disposed facing the valve body seating portion 57 of the poppet valve body 12A. Two negative pressure passages 71 are formed as shown in FIG. 3, and two negative pressure passage openings 72 are also provided correspondingly. A ring-shaped edge portion of the negative pressure passage opening 72 forms a negative pressure valve seat 73 so that the valve body seating portion 57 can be seated. In other words, the valve body seating part 57 opens and closes the negative pressure passage opening 72 by the seating with respect to the negative pressure valve seat 73.
In this case, the space surrounded by the tubular portion 39, the tubular portion inner tubular body 74, and the poppet valve body 12A in the rear region of the valve body seating / separating seat 57 (poppet valve body 12A) facing the negative pressure passage opening 72. (Hereinafter referred to as the space behind the poppet valve body) 70A communicates with the variable pressure chamber 4 through the atmospheric passage 25, while the negative pressure passage 71 is in a state where the valve body separation seat 57 is seated on the negative pressure valve seat 73. Communication with is interrupted.

The tubular portion inner cylinder 74 is fitted to the tubular portion distal end portion 39A. The cylindrical portion inner cylindrical body 74 includes a cylindrical main body 75, a cylindrical thick portion 76 that is connected to one end side of the cylindrical main body 75 and has a thickness dimension larger than that of the cylindrical main body 75, and the cylindrical main body 75. The cylindrical first flange 77 is formed on the other end side so as to project radially outward and is in contact with the cylindrical portion opening 39a and used for positioning with respect to the valve body 6.
An annular groove 79 is formed on the outer peripheral side of the cylindrical thick portion 76 to house the O-ring 78 and fix it.
A cylindrical second flange 80 projecting radially inward is formed on the front side (leftward in FIG. 2) of the cylindrical thick part 76, and is fitted to the inner peripheral side of the cylindrical thick part 76. The poppet valve element base end 55 of the poppet valve element 12A is sealed and the poppet valve element 12A is prevented from coming off.

The cylindrical second flange 80 is formed with an annular projection 81 protruding forward (leftward in FIG. 2) so as to lock one end of the poppet spring 16A.
Further, a poppet retainer 82 is disposed in the tubular portion 39 so that the poppet valve body base end portion 55 of the poppet valve body 12A can be pressed from the inner peripheral side. The poppet retainer 82 fixes the poppet valve body base end portion 55 to the cylindrical body thick portion 76 and locks the valve spring 15.

The valve body 6 is normally urged to the rear side (right side in FIG. 1) by a return spring 26 disposed in the constant pressure chamber 3, and when the atmospheric pressure booster 1A is not operated, the valve body 6 enters the radial hole 27a. The inserted stop key 27 is positioned at the original position where it abuts against the stepped surface 29 inside the small-diameter cylindrical portion 40 of the rear shell 28.
For example, engine negative pressure is introduced into the constant pressure chamber 3 through a vent 41 provided in the front shell 30, and this negative pressure is interlocked with an input rod 7 extended from a brake pedal (not shown). By the operation of the valve mechanism 9, the variable pressure chamber 4 is also supplied through the negative pressure passage 71 and the atmospheric passage 25.

  On the other hand, a silencer filter 42 and a dustproof filter 43 are arranged in a cylindrical part inner cylinder 74 arranged on the cylindrical part opening 39a side of the cylindrical part 39, and the atmosphere is cylindrical through the filters 42 and 43. It is introduced into the partial space 37. This atmosphere is supplied to the variable pressure chamber 4 through the atmosphere passage 25 by the operation of the valve mechanism 9. Here, the muffling filter 42 and the dustproof filter 43 have a ring shape, and the input rod 7 is extended through the inner diameter portions of the filters 42 and 43. Further, the filter 42, 43 has a bottomed cylindrical dust boot 44 having a mouth portion fitted to the small diameter cylindrical portion 40 of the rear shell 28 and covering the cylindrical portion 39 and the cylindrical portion inner cylindrical body 74 of the valve body 6. It is secured by.

  The valve mechanism 9 includes a plunger 8 slidably fitted in a shaft hole 36 formed in the valve body main body 38. As shown in FIG. 2, a silencer filter 42 and a rear end portion (hereinafter referred to as a plunger input rod connecting portion) 45 of the plunger 8 and a hole portion (not shown) formed in a plunger main body portion 48 to be described later are provided. A distal end portion (not shown) of the input rod 7 extending through the dustproof filter 43 is inserted and connected. The input rod 7 moves forward in the left direction in FIG. 1 according to the depression of the brake pedal, and the plunger 8 also moves forward together therewith.

  The plunger 8 is connected to a plunger input rod connecting portion 45 with a plunger main body portion 48 having a larger diameter than that of the plunger input rod connecting portion 45, and a shaft having a smaller diameter than the plunger input rod connecting portion 45 is connected to the front side of the plunger main body portion 48. A portion (hereinafter referred to as a plunger shaft portion) 49 is extended. The plunger shaft portion 49 is inserted into the shaft hole 36, and the tip surface portion thereof is disposed so as to be able to contact the reaction disk 21.

  As shown in FIG. 2, the valve mechanism 9 includes an annular atmospheric valve seat 20 formed at the rear end (plunger input rod connecting portion 45) of the plunger 8, the negative pressure valve seat 73, and the both valve seats. The poppet valve body 12A is disposed in the cylindrical portion 39 (cylindrical portion space 37) so as to be separable from the seats 20 and 23, and one end of the poppet valve body 12A is locked to the thick portion 76 of the cylindrical body. And a poppet spring 16 </ b> A that presses the valve body seating part 57 in the direction in which the valve seats 20 and 23 are seated. The poppet spring 16A is disposed on the back side of the poppet valve body 12A (poppet valve body back space 70A) as shown in FIG.

  The poppet valve body 12 </ b> A is disposed on the valve body 6 through the cylindrical portion inner cylinder 74, and has a substantially cylindrical poppet valve body base end portion 55 on the inner peripheral end side of the poppet valve body base end portion 55. A substantially cylindrical bellows part 56 connected to the base end side and a substantially annular valve body seating part 57 provided on the front end side of the bellows part 56 are roughly constituted. The bellows portion 56 has a diameter that gradually increases from the distal end side toward the proximal end side, and is arranged between the poppet valve body rear surface side space 70 </ b> A and the tubular portion space 37. Further, since the poppet valve body base end portion 55 is fixed to the cylindrical body thick portion 76 as described above, the poppet valve body base end portion 55 is fixed to the inner peripheral side of the cylindrical portion 39 as compared with the related art. In the present embodiment, the poppet valve body base end portion 55, the bellows portion 56, and the valve body seating portion 57 are integrally formed of the same flexible material.

The valve mechanism 9 comprises the atmospheric valve 10 by an atmospheric valve seat 20 and an inner peripheral side portion (reference numeral omitted) on the front surface side (left side in FIG. 2) of the valve body attaching / detaching seat portion 57 of the poppet valve body 12A in contact therewith. The vacuum valve 11A is constituted by the negative pressure valve seat 73 and the outer peripheral side portion (reference numeral omitted) on the front surface side (left side in FIG. 2) of the valve body seating portion 57 of the poppet valve body 12A in contact with the negative pressure valve seat 73. The atmosphere 4 or negative pressure is selectively supplied to the chamber 4 according to the opening of the atmosphere valve 10 or the vacuum valve 11A.
The atmospheric valve 10 is configured as described above to communicate / block the variable pressure chamber 4 and the atmosphere, and the vacuum valve 11A is configured as described above to communicate / block between the constant pressure chamber 3 and the variable pressure chamber 4. Like to do.

  Here, the poppet valve body 12A constituting the valve mechanism 9 is fixed to the valve body 6 by a poppet retainer 82 that receives one end of a valve spring 15 that urges the input rod 7 to the rear side. The other end of the valve spring 15 is locked to a flange portion 66 provided integrally with the input rod 7, whereby the input rod 7 is normally urged in the return direction toward the rear side, and this movement causes the plunger to move. 8 also works. The plunger 8 has its relative movement range restricted with respect to the valve body 6 by a stop key 27 inserted in the radial hole 27a of the valve body 6. When the pneumatic booster 1A is not operated, as shown in FIG. The return end of the plunger 8 is regulated by the stop key 27, and the poppet valve body 12A maintains the closed state in contact with the atmospheric valve seat 20 and the negative pressure valve seat 73.

  On the other hand, the reaction disc 21 and the base end cup portion 68 of the output rod 22 are arranged on the front end side of the valve body 6, and the distal end of the plunger shaft portion 49 of the plunger 8 is slightly with respect to the back surface of the reaction disc 21. It is positioned so as to open a gap. The tip of the output rod 22 passes through the constant pressure chamber 3 and the front shell 30 so that a piston in a master cylinder (not shown) is operatively connected. The proximal end cup portion 68 of the output rod 22 and the reaction disk 21 are secured by a retainer 69 that is pressed and fixed to the front end of the valve body 6 by a return spring 26.

Hereinafter, the operation of the atmospheric pressure booster 1A will be described.
The pneumatic booster 1A is attached to a vehicle body (not shown) using a plurality of stud bolts 80 protruding from the rear surface of the rear shell 28, while using a stud bolt 81 protruding from the front surface of the front shell 30. A master cylinder (not shown) is coupled to the atmospheric pressure booster 1A.

  When a brake pedal (not shown) is depressed in this attached state, the input rod 7 moves forward and the plunger 8 moves forward, and the atmospheric valve seat 20 at the rear end of the plunger 8 moves away from the poppet valve body 12A. Then, the atmospheric valve 10 opens. As a result, the atmosphere flows into the valve body 6 through the silencer filter 42 and the dustproof filter 43, and this atmosphere is further introduced from the atmosphere valve 10 through the atmosphere passage 25 into the variable pressure chamber 4. As a result, a pressure difference is generated between the constant pressure chamber 3 into which the negative pressure is introduced and the variable pressure chamber 4 into which the atmosphere is introduced, and the power piston 5 including the valve body 6 is propelled by this pressure difference, and its thrust Is output from the valve body 6 through the output rod 22 to the master cylinder side. On the other hand, a part of the reaction force due to the output is transmitted from the output rod 22 to the input rod 7 via the reaction disk 21 and the plunger 8, thereby performing a boosting action in which the output increases in accordance with an increase in input.

At the start of this boosting action, when the atmospheric valve 10 is opened, the negative pressure passage 71 which is in a negative pressure state is blocked from the poppet valve body rear side space 70A, while the poppet valve Air is introduced into the body back side space 70A. Then, due to the pressure difference between the negative pressure passage 71 and the poppet valve body rear side space 70 </ b> A, the valve body seating portion 57 receives a pressure in the direction of closing the negative pressure passage 71 side, that is, the negative pressure valve seat 73. As a result, when the atmospheric valve 10 is opened, the spring force required to close the vacuum valve 11A can be reduced, and consequently the invalid input can be reduced.
Since the invalid input can be reduced in this way, it is not necessary to increase the pedal effort even when the pedal ratio is reduced as required along with the longer stroke. In other words, it is possible to achieve a longer stroke (and consequently a lower pedal ratio) without increasing the pedal effort.

  Moreover, since the front end side of the bellows part 56 is connected to the inner diameter side part of the valve body attaching / detaching seat part 57, the poppet valve body rear side space 70A can be widened, and the poppet spring 16A is connected to the poppet valve body rear side space. A space for 70A can be secured. Moreover, since the effective radius of the bellows part 56 can be made smaller than before, the area of the differential pressure acting on the bellows part 56 is reduced. Accordingly, the differential pressure is reduced, so that the valve spring force can be reduced, and as a result, the invalid input can be reduced. In the present embodiment, the poppet spring 16A is disposed in the space 70A on the back surface of the poppet valve body thus widened, and the poppet spring 16A is interposed between the cylindrical body thick part 76 and the valve body seating part 57. . For this reason, the spring force of the poppet spring 16A acts as a pressing force with respect to the vacuum valve 11A to ensure the sealing performance. Further, when the atmosphere is introduced into the variable pressure chamber 4, the poppet spring 16A is not passed through, so that there is an effect of reducing air communication noise.

  Moreover, in the said embodiment, although the pneumatic booster 1A was comprised as what is called a single type provided with one power piston 5, this invention is comprised as a tandem type provided with two power pistons. Of course it is good.

1 is a cross-sectional view schematically showing a pneumatic booster according to a first embodiment of the present invention. It is the elements on larger scale of FIG. It is a front view which shows the part containing the negative pressure channel | path opening part of the valve body of FIG. It is sectional drawing which shows the conventional pneumatic type booster typically.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1A ... Pneumatic pressure booster, 2 ... Shell main body, 3 ... Constant pressure chamber, 4 ... Transformer chamber, 5 ... Power piston, 6 ... Valve body, 7 ... Input rod, 8 ... Plunger, 9 ... Valve mechanism, 10 ... Atmosphere Valve, 11A ... Vacuum valve, 12A ... Poppet valve body, 15 ... Valve spring, 16A ... Poppet spring, 20 ... Air valve seat, 21 ... Reaction disk, 39 ... Cylindrical part, 56 ... Bellows, 57 ... Valve Separator / seat part, 70A ... Poppet valve body rear side space, 71 ... Negative pressure passage, 72 ... Negative pressure passage opening, 73 ... Negative pressure valve seat.

Claims (3)

The inside of the shell body is divided into a constant pressure chamber and a variable pressure chamber by a power piston. A valve mechanism that is linked to a plunger connected to the valve body, and a negative pressure that opens to the valve body as a negative pressure passage opening at one end side communicating with the constant pressure chamber and at the other end side to the inner peripheral surface of the cylindrical portion. As the input rod moves forward, the valve mechanism is actuated to introduce the atmosphere into the variable pressure chamber through the opening of the cylindrical portion, thereby creating a pressure difference between the constant pressure chamber and the variable pressure chamber. A pneumatic booster that generates and propels the power piston by this pressure difference,
The negative pressure passage opening opens toward the base end side of the input rod,
The valve mechanism includes an annular atmospheric valve seat formed at a rear end of the plunger, a negative pressure valve seat formed at a circumferential edge of the negative pressure passage opening, the atmospheric valve seat, and the A poppet valve body disposed on the negative pressure valve seat so as to be separable; and
The poppet valve body opens and closes the negative pressure passage opening by means of a release seat with respect to the negative pressure valve seat,
The space on the back side of the poppet valve body surrounded by the tubular portion and the poppet valve body in the back region of the poppet valve body facing the negative pressure passage opening portion is in communication with the variable pressure chamber. Pneumatic booster.   The poppet valve body includes a substantially cylindrical poppet valve body base end portion fixed to the tubular portion of the valve body via a cylindrical body provided inside the tubular portion, and a poppet valve body base end portion A substantially cylindrical bellows portion connected to the front end of the bellows portion, an annular valve body seating portion that is connected to the tip end side of the bellows portion and seats on and off the atmospheric valve seat and the negative pressure valve seat, and the valve body separation A poppet spring that presses the seating portion in the direction of seating on the atmospheric valve seat and the negative pressure valve seat, and the connection to the valve body seating portion on the tip side of the bellows portion is connected to the valve body seating portion. The pneumatic booster according to claim 1, wherein the booster is carried out at an inner diameter side portion of the pneumatic pressure booster. 3. The pneumatic booster according to claim 1, wherein the poppet spring is interposed between the valve body attaching / detaching seat portion and the cylindrical portion.

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