JP6179425B2 - Pneumatic booster - Google Patents

Description

  The present invention relates to a pneumatic booster used as a negative pressure booster in a vehicle brake device, for example.

  In general, a brake system of a vehicle is provided with a pneumatic booster between a brake pedal and a master cylinder. This type of pneumatic booster boosts the pedaling force applied from the brake pedal to the input rod according to the pressure difference between the internal negative pressure chamber and the variable pressure chamber, thereby generating a large output from the output rod to the master cylinder. It is configured to be taken out to the side. In the pneumatic booster, the center shell provided between the front shell and the rear shell defined the inside of the housing into two chambers, and each of the two chambers was provided with a negative pressure chamber and a variable pressure chamber. A so-called tandem type pneumatic booster is known.

  In this tandem type pneumatic booster, a master cylinder and a mounting member (rod) for mounting to a vehicle pass through a center shell and a front shell and a rear shell provided before and after the center shell. Then, a cylindrical member penetrating the mounting member is provided in the rear shell side chamber (rear chamber), and the rear shell side variable pressure chamber and the front shell side variable pressure chamber communicate with each other through the through hole of the cylindrical member ( For example, see Patent Document 1).

JP 2005-161881 A

  By the way, the attachment member of the pneumatic booster according to the prior art forms a step portion for locking the support plate on the front shell side. Further, the cylindrical member is provided with a plurality of protrusions for forming a passage with the mounting member, and the cylindrical member is assembled beyond the stepped portion that locks the support plate. Therefore, the outer diameter of the mounting member is set in accordance with the inner diameter connecting the tips of the protrusions of the cylindrical member, and is substantially the same diameter as the large diameter side of the stepped portion. As a result, there is a problem that the weight of the pneumatic booster increases due to the large diameter portion that occupies most of the axial dimension of the mounting member.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a pneumatic booster that is reduced in weight.

  In order to solve the above-described problem, the present invention provides a third shell that defines a plurality of chambers in a housing composed of a first shell and a second shell, and penetrates the first to third shells. And an attachment member provided with an engaging portion that engages with the vehicle and the master cylinder at an end portion, and one end side is held by the third shell and is provided in one of the plurality of chambers. And a cylindrical member that has a through-hole through which the mounting member is inserted, and the through-hole serves as a communication path that communicates the plurality of chambers.

  A feature of the configuration employed by the present invention is that the tubular member is formed with a protrusion extending in the center direction of the through hole, and the mounting member is formed on the center side in the axial direction of each engaging portion. A flange portion that abuts against the first and second shells is provided, and at least one of the flange portions is provided with a groove portion through which the projection of the tubular member can be inserted.

  According to the present invention, it is possible to reduce the weight of the pneumatic booster.

1 is a longitudinal sectional view showing a pneumatic booster according to an embodiment of the present invention. It is a front view which expands and shows the attachment member in FIG. It is sectional drawing which looked at the attachment member in FIG. 2 from the arrow III-III direction. It is a front view which shows a cylindrical member alone. It is sectional drawing which looked at the cylindrical member in FIG. 4 from the arrow VV direction. It is sectional drawing which looked at the attachment member by the 1st modification from the same direction as FIG. It is sectional drawing which looked at the cylindrical member from the same direction as FIG. It is sectional drawing which looked at the attachment member by the 2nd modification from the same direction as FIG.

  Hereinafter, as a pneumatic booster according to an embodiment of the present invention, a tandem pneumatic booster applied to a vehicle brake device will be described as an example and described in detail with reference to the accompanying drawings.

  1 to 5 show an embodiment of the present invention. In FIG. 1, a pneumatic booster 1 has a housing 2 that constitutes an outer shell thereof, and the housing 2 is a front shell 3 as a first shell located near the front side of a vehicle (not shown). And a rear shell 4 as a second shell located on the rear side. A center shell 5 is provided between the front shell 3 and the rear shell 4 as a third shell that defines the inside of the housing 2 into two chambers, a front chamber A and a rear chamber B. The shells 3, 4 and 5 are fixed in an airtight state on the outer peripheral side.

  The front shell 3 is formed with a cylindrical recess 3B for housing a part of a master cylinder (not shown) at the center of the front wall 3A. Here, the cylindrical recess 3B of the front shell 3 is provided with an annular seal member (not shown) that hermetically seals with the master cylinder. This sealing member seals the negative pressure chamber A1 in the housing 2 in an airtight state against the external atmosphere. Further, the front wall 3A is located on the outer side in the radial direction from the cylindrical recess 3B, and introduces a negative pressure introduction communicating with a front side insertion hole 3C through which a mounting member 24 described later is inserted and a negative pressure introducing tube 23 described later. A hole 3D is formed.

  The rear shell 4 is provided with a rear cylinder portion 4B protruding outward in the axial direction from the center portion of the rear wall 4A that is a mounting surface for a vehicle body (not shown). Further, the rear shell 4 is provided with an annular step portion 4C at an intermediate position in the axial direction (length direction) of the rear cylinder portion 4B. A stop key 18 (described later) abuts on the stepped portion 4C when a push operation of the input rod 10 (described later) is released, thereby restricting the return positions of the valve body 8 and the plunger 16 (refer to FIG. 1). Further, the rear wall 4A is formed with a rear side insertion hole 4D which is located on the outer side in the radial direction with respect to the rear cylinder portion 4B and into which a mounting member 24 described later is inserted.

  On the other hand, the center shell 5 is located between the front shell 3 and the rear shell 4, and the front chamber A formed between the front shell 3 and the center shell 5 in the housing 2, and the rear shell 4 and the center shell 5. And a rear chamber B formed between the two. Further, the center shell 5 is formed with a valve body insertion hole 5A through which a later-described valve body 8 is inserted in the center thereof, and a cylindrical member described later is positioned at a radially outer side of the valve body insertion hole 5A. A cylindrical member mounting hole 5B for holding one end side of 30 is formed.

  A power piston 6 made of a diaphragm or the like is provided in the front chamber A in the housing 2. The power piston 6 has an outer peripheral side fixed between the front shell 3 and the center shell 5, and an inner peripheral side fixed to a later-described valve body 8. Further, a shaft portion 24A of a mounting member 24 described later is slidably fitted into the power piston 6. In the front chamber A, a negative pressure chamber A1 is formed between the front shell 3 and the power piston 6, and a variable pressure chamber A2 is formed between the power piston 6 and the center shell 5.

  On the other hand, a power piston 7 made of a diaphragm or the like is provided in the rear chamber B in the housing 2. The power piston 7 has an outer peripheral side fixed between the rear shell 4 and the center shell 5, and an inner peripheral side fixed to a later-described valve body 8. A cylindrical member 30 described later is slidably inserted into the power piston 7. In the rear chamber B, a negative pressure chamber B1 is provided between the center shell 5 and the power piston 7, and a variable pressure chamber B2 is provided between the power piston 7 and the rear shell 4.

  The valve body 8 inserted into the rear cylinder portion 4B of the rear shell 4 is provided in the housing 2 so as to be displaceable in the axial direction (left and right directions in FIG. 1). The valve body 8 is formed in a stepped shape using a high-strength resin material, for example, by a main body portion 8A located on the master cylinder side and a small-diameter cylindrical portion 8B located on the vehicle body attachment side.

  The body 8A of the valve body 8 is slidably fitted into the valve body insertion hole 5A of the center shell 5 via the seal member 9, and is connected (fixed) to the inner peripheral side of the power pistons 6 and 7. . On the other hand, the small-diameter cylindrical portion 8B of the valve body 8 extends from the rear cylindrical portion 4B of the rear shell 4 toward the outside of the housing 2 on the vehicle body attachment side (right side in FIG. 1). The valve body 8 is displaced in the axial direction in the housing 2 in conjunction with the displacement of the power pistons 6 and 7.

  The valve body 8 is always in communication with the negative pressure chamber A1 and extends in the axial direction from the main body portion 8A toward the small diameter cylindrical portion 8B, and the axial passage 8C and the negative pressure chamber B1 are always in communication. A radial passage 8D is formed. That is, the negative pressure chamber A1 in the front chamber A and the negative pressure chamber B1 in the rear chamber B are always in communication with each other through the axial passage 8C and the radial passage 8D of the valve body 8.

  In the small diameter cylindrical portion 8B of the valve body 8, another radial passage 8E is formed at a position different from the axial passage 8C and the radial passage 8D. The radial passage 8E is always in communication with the variable pressure chamber A2 and the variable pressure chamber B2. The axial passage 8C, the radial passage 8D, and the radial passage 8E communicate and block the negative pressure chambers A1 and B1 and the variable pressure chambers A2 and B2 as the valve body 8 is displaced in the axial direction. It is.

  Further, a key insertion hole 8 </ b> F is formed in the valve body 8 at a position corresponding to the step portion 4 </ b> C of the rear shell 4. A stop key 18 described later is inserted into the key insertion hole 8F. The valve body 8 is formed with an annular valve seat portion 8G at the opening end of the axial passage 8C on the vehicle body mounting side. A poppet valve body 11, which will be described later, is configured to be separated from and seated on the valve seat portion 8G. The valve body 8 is integrally formed with a cylindrical projecting portion 8H that is located on the inner peripheral side of the main body portion 8A and projects in the axial direction toward the output rod 19 described later.

  The input rod 10 that extends in the valve body 8 in the axial direction protrudes outward from the rear cylinder portion 4B of the rear shell 4 on the vehicle body mounting side, and is inserted into the small diameter cylinder portion 8B of the valve body 8 on the master cylinder side (left side in FIG. 1). Has been. The input rod 10 is connected to a brake pedal (not shown) of the vehicle on the protruding end side, and is pushed in the direction of arrow C in FIG. Further, a spherical portion 10A is integrally formed on the distal end side of the input rod 10, and the spherical portion 10A is connected to a plunger 16 described later using means such as caulking.

  The poppet valve body 11 that is located on the outer peripheral side of the input rod 10 and is provided in the small-diameter cylindrical portion 8B of the valve body 8 is formed in a substantially cylindrical shape by an elastic material. The body mounting side of the poppet valve body 11 is pressed and fixed to the inner peripheral side of the valve body 8 by a return spring 13 described later. The master cylinder side of the poppet valve body 11 is constantly urged by the weak spring 12 toward the valve seat portion 8G of the valve body 8. Thereby, the poppet valve body 11 is separated from and seated on a valve seat portion 8G of the valve body 8 and a contact portion 16A of the plunger 16 described later.

  A return spring 13 disposed between the small-diameter cylindrical portion 8B of the valve body 8 and the input rod 10 constantly urges the input rod 10 toward the vehicle body mounting side with respect to the valve body 8. As a result, when the pushing operation (braking operation) on the input rod 10 is released, the valve body 8 moves in the direction of the arrow D in the housing 2 and is regulated by an initial position shown in FIG. The input rod 10 is pressed by the return spring 13 until it returns to the position).

  The filter 14 attached to the opening on the vehicle body mounting side of the valve body 8 cleans the air as working gas introduced from the outside of the housing 2 into the small diameter cylindrical portion 8B of the valve body 8, and dust or the like is generated in the housing 2. It suppresses intrusion. The protective boot 15 mounted on the outer peripheral side of the small-diameter cylindrical portion 8B of the valve body 8 is formed as an accordion-shaped cylindrical body with an elastic material, and protects the protruding end side of the valve body 8 from external dust or the like. It is.

  The plunger 16 fixed to the spherical portion 10 </ b> A of the input rod 10 is inserted on the inner peripheral side of the valve body 8 so as to be displaceable in the axial direction. That is, the plunger 16 is configured to be displaced in the axial direction integrally with the input rod 10. The body mounting side of the plunger 16 is an abutting portion 16 </ b> A formed with a smaller diameter than the valve seat portion 8 </ b> G of the valve body 8. The abutting portion 16A introduces air (atmospheric pressure) introduced into the small-diameter cylindrical portion 8B of the valve body 8 through the filter 14 to the radial passage 8E side by being separated from and seated on the poppet valve body 11. Or shut off the introduction of air.

  That is, the contact portion 16A of the plunger 16 is separated from and seated on the poppet valve body 11, thereby communicating and blocking the variable pressure chambers A2 and B2 with respect to the atmospheric pressure in the small diameter cylindrical portion 8B of the valve body 8. Further, when the poppet valve body 11 is separated from and seated on the valve seat portion 8G of the valve body 8, the variable pressure chambers A2 and B2 are connected to and disconnected from the negative pressure chambers A1 and B1. An annular groove 16B is formed on the outer peripheral side of the plunger 16 at a position corresponding to the key insertion hole 8F of the valve body 8, and a stop key 18 described later is attached to the annular groove 16B in an engaged state. Yes.

  The moving body 17 constituting a part of the plunger 16 moves (displaces) in the axial direction within the cylindrical protrusion 8H of the valve body 8. The master cylinder side of the moving body 17 is inserted into the inner peripheral side of the cylindrical projecting portion 8H of the valve body 8 and abuts on a reaction disk 22 described later.

  The stop key 18 that regulates the return position of the plunger 16 is formed using a substantially rectangular flat plate, and is engaged with the annular groove 16 </ b> B of the plunger 16 through the key insertion hole 8 </ b> F of the valve body 8 in a loosely fitted state. . The end portion of the stop key 18 protrudes from the valve body 8 by a certain dimension in the radial direction, and can come into contact with the step portion 4 </ b> C of the rear shell 4. That is, when the pushing operation on the input rod 10 is released, the stop key 18 abuts against the stepped portion 4C of the rear shell 4 to restrict the return positions of the valve body 8 and the plunger 16 as shown in FIG. is there.

  The output rod 19 that outputs to the master cylinder in a state where the pushing operation force of the input rod 10 is boosted is provided with a large-diameter flange portion 19A on the vehicle body mounting side, and the flange portion 19A has a reaction disk 22 described later. The tubular projecting portion 8H of the valve body 8 is fitted to the tubular projecting portion 8H so as to cover the tubular projecting portion 8H of the valve body 8.

  The output rod 19 is pushed with a large output in the direction of arrow C in FIG. 1 together with the valve body 8 when the input rod 10 is pushed. That is, the master cylinder side of the output rod 19 protrudes in the axial direction toward the cylindrical recess 3B of the front shell 3, and the piston of the master cylinder (output) is a force (output) obtained by boosting the pushing operation force of the input rod 10. (Not shown) is configured to press in the axial direction.

  A spring receiver 20 provided on the inner peripheral side of the main body portion 8A of the valve body 8 is attached to the outer peripheral side of the cylindrical protruding portion 8H via the flange portion 19A of the output rod 19, and the flange portion 19A with respect to the cylindrical protruding portion 8H. It is the structure which performs removal prevention of this with the return spring 21. FIG. Here, the return spring 21 is disposed between the spring receiver 20 and the cylindrical recess 3B of the front shell 3, and constantly urges the valve body 8 toward the vehicle body mounting side.

  The reaction disk 22 disposed between the cylindrical protruding portion 8H of the valve body 8 and the flange portion 19A of the output rod 19 is formed in a disk shape using a rubber material or the like that can be elastically deformed. The reaction disk 22 transmits the thrust generated in the valve body 8 to the output rod 19 due to the pressure difference generated between the negative pressure chambers A1, B1 and the variable pressure chambers A2, B2.

  As shown in FIG. 1, the negative pressure introduction pipe 23 provided on the front wall 3A of the front shell 3 is composed of a pipe or the like communicating with the negative pressure introduction hole 3D provided on the front wall 3A of the front shell 3. The intake manifold is connected via a check valve (both not shown). The negative pressure introducing pipe 23 guides the negative pressure generated in the intake manifold during the operation of the engine into the negative pressure chambers A1 and B1, thereby reducing the pressure in the negative pressure chambers A1 and B1 to be lower than the atmospheric pressure. It is something to hold.

  A mounting member 24 provided from the front shell 3 to the rear shell 4 through the center shell 5 attaches the pneumatic booster 1 to the vehicle body (vehicle) and the master cylinder. For example, two mounting members 24 (only one is shown) are provided spaced apart in the circumferential direction on the outer peripheral side of the small-diameter cylindrical portion 8B of the valve body 8. The mounting member 24 includes a shaft portion 24A, a vehicle body mounting bolt 24B, a master cylinder mounting bolt 24C, a rear side flange portion 26, and a front side flange portion 27.

  The shaft portion 24 </ b> A of the attachment member 24 is formed as a solid cylindrical body that extends between the front chamber A and the rear chamber B in the housing 2 in the axial direction. Specifically, the shaft portion 24 </ b> A extends from the front side insertion hole 3 </ b> C of the front shell 3 through the power piston 6, the center shell 5, and the power piston 7 to the rear side insertion hole 4 </ b> D of the rear shell 4. The power piston 6 is slidably attached to a portion of the shaft portion 24A located on the front chamber A side. Further, the central portion of the shaft portion 24 </ b> A is inserted through a cylindrical member attachment hole 5 </ b> B of the center shell 5 through a cylindrical member 30 described later. And the part located in the back chamber B side among shaft part 24A is penetrated to the through-hole 30F of the cylindrical member 30 mentioned later.

  The vehicle body mounting bolt 24B as the engaging portion is connected to the end portion of the shaft portion 24A on the vehicle body mounting side and protrudes from the rear side insertion hole 4D of the rear shell 4 toward the vehicle body mounting side. On the other hand, the master cylinder mounting bolt 24C as the engaging portion is connected to the end portion of the shaft portion 24A on the master cylinder side and protrudes from the front side insertion hole 3C of the front shell 3 toward the master cylinder side. That is, the vehicle body mounting bolt 24B and the master cylinder mounting bolt 24C are integrally formed via the shaft portion 24A. In this case, the outer diameter dimension of the shaft portion 24A, the outer diameter dimension of the vehicle body mounting bolt 24B, and the outer diameter dimension of the master cylinder mounting bolt 24C are formed to be substantially the same dimension.

  In addition to the vehicle body mounting bolt 24B, another vehicle body mounting bolt 25 (only one is shown) is provided on the outer peripheral side of the small diameter cylindrical portion 8B. The pneumatic booster 1 is attached to a vehicle body (not shown) by vehicle body mounting bolts 24B and 25 (only one of each is shown), and is attached to a master cylinder (not shown) by a master cylinder mounting bolt 24C (only one is shown). It is configured to be attached.

  The rear flange portion 26 as the flange portion is provided on the axial center side of the vehicle body mounting bolt 24B in the shaft portion 24A. The rear flange portion 26 is formed in a disk shape, and the outer diameter dimension thereof is substantially the same as or slightly larger than the outer diameter dimension of a tubular member 30 described later. The rear side flange portion 26 is provided in the shaft portion 24 </ b> A so as to be in the variable pressure chamber B <b> 2 and is in contact with the rear shell 4. The rear flange portion 26 (attachment member 24) is fixed to the rear shell 4 by pressing the rear flange portion 26 to the rear shell 4.

  On the other hand, the front side flange portion 27 as a flange portion is provided on the axial center side of the master cylinder mounting bolt 24C in the shaft portion 24A. The front flange portion 27 holds a support plate 28 described later in the axial direction. As shown in FIG. 3, the front flange portion 27 includes three projecting portions 27A projecting radially outward from the shaft portion 24A, It is comprised by the three groove parts 27B located between protrusion part 27A.

  In this case, the front side flange portion 27 is formed so as to be able to be inserted into a through hole 30F of a cylindrical member 30 described later (see FIG. 5). Each protrusion 27A of the front flange portion 27 is inserted between each radial protrusion 30G of the cylindrical member 30 described later. In other words, the groove portion 27B of the front side flange portion 27 is formed so that a radial projection 30G of a cylindrical member 30 described later can be inserted therethrough. The front flange portion 27 is located in the negative pressure chamber A1 and provided on the shaft portion 24A, and is in contact with the front shell 3 via a support plate 28 described later.

  The support plate 28 inserted through the shaft portion 24 </ b> A of the attachment member 24 is provided between the front shell 3 and the front flange portion 27. The support plate 28 is made of a disk-shaped plate material, and an insertion hole 28A through which the shaft portion 24A is inserted is provided at the center. Between the support plate 28 and the front shell 3, a seal member 29 is provided in close contact between the shaft portion 24A of the mounting member 24 and the insertion hole 28A. As a result, the space between the front shell 3 and the shaft portion 24A of the mounting member 24 is sealed to ensure airtightness in the negative pressure chamber A1.

  The cylindrical member 30 provided in the rear chamber B with one end side (master cylinder side) held by the center shell 5 communicates between the variable pressure chamber A2 and the variable pressure chamber B2. An annular groove 30C that is recessed radially outward from the outer peripheral surface 30B and extending in the circumferential direction is formed at a position near the one end surface 30A of the cylindrical member 30, that is, on the vehicle body mounting side relative to the one end surface 30A. . An annular flange 30D protruding from the outer peripheral surface 30B is provided at a position in the vicinity of the annular groove 30C, that is, on the vehicle body attachment side with respect to the annular groove 30C. In other words, the annular groove 30C is formed between the one side end face 30A and the flange 30D.

  An O-ring 31 formed of an elastic material such as rubber is fitted in the annular groove 30C. Then, the cylindrical member 30 is held in the center shell 5 by press-fitting one end side of the cylindrical member 30 into the cylindrical member mounting hole 5B of the center shell 5 and bringing the flange portion 30D into contact with the center shell 5. be able to. In this case, the O-ring 31 fitted in the annular groove 30C is elastically deformed between the cylindrical member 30 and the center shell 5, so that an airtight state in the negative pressure chamber B1 can be ensured. On the other hand, the other end side of the cylindrical member 30 supports the power piston 7 so as to be slidable. That is, the power piston 7 can slide in the axial direction along the outer peripheral surface 30 </ b> B of the cylindrical member 30.

  Moreover, the inside of the cylindrical member 30 is a through hole 30F that penetrates between the one side end face 30A and the other side end face 30E. That is, one side of the through hole 30F opens to the variable pressure chamber A2, and the other side of the through hole 30F opens to the variable pressure chamber B2. The hole diameter of the through hole 30 </ b> F is larger than the outer diameter dimension of the shaft portion 24 </ b> A of the mounting member 24, and further larger than the outer diameter dimension of the front flange portion 27. The cylindrical member 30 has a radial protrusion 30G as a plurality of (for example, three) protrusions extending in the central direction (radially inner side) of the through hole 30F and extending along the axial direction of the through hole 30F. An axial protrusion 30 </ b> H is formed at the end of each radial protrusion 30 </ b> G and protrudes outward in the axial direction from the other end face 30 </ b> E of the cylindrical member 30.

  As shown in FIG. 5, each radial protrusion 30 </ b> G is provided at a position corresponding to the groove portion 27 </ b> B of the front flange portion 27, and the central side (radially inner side) of each radial protrusion 30 </ b> G is the axis of the mounting member 24. It is close to the part 24A. As a result, the shaft portion 24A can be positioned substantially at the center (center side) of the through hole 30F, and a gap can be formed between the shaft portion 24A and the through hole 30F. This gap serves as a communication path 32 that communicates between the variable pressure chamber A2 in the front chamber A and the variable pressure chamber B2 in the rear chamber B. Therefore, the variable pressure chamber A2 of the front chamber A communicates with the radial passage 8E of the valve body 8 via the communication passage 32 and the variable pressure chamber B2.

  Here, the cylindrical member 30 is disposed in the rear chamber B in a state of being sub-assembled to the mounting member 24. In this case, the front side flange portion 27 provided on the shaft portion 24A of the attachment member 24 is formed with a groove portion 27B through which the radial protrusion 30G of the tubular member 30 can be inserted. The member 24 can be inserted from the master cylinder mounting bolt 24C side. Further, the support plate 28 can be supported (positioned) with respect to the front shell 3 by the protruding portion 27 </ b> A of the front flange portion 27.

  The pneumatic booster 1 according to the present embodiment has the above-described configuration, and the operation thereof will be described next.

  First, the pneumatic booster 1 defines the inside of a housing 2 into a front chamber A and a rear chamber B by a center shell 5, and the inside of the front chamber A to a negative pressure chamber A1 and a variable pressure chamber A2 by a power piston 6. This is a so-called tandem pressure booster in which the rear chamber B is defined by the power piston 7 into a negative pressure chamber B1 and a variable pressure chamber B2.

  When the driver of the vehicle depresses the brake pedal, the input rod 10 is pushed in the direction indicated by the arrow C, and the plunger 16 is displaced along with the moving body 17 in the axial direction. In this case, since the movement of the poppet valve body 11 is restricted by the valve seat portion 8G of the valve body 8, the contact portion 16A of the plunger 16 is separated from the poppet valve body 11. Thereby, atmospheric pressure is introduced into the variable pressure chamber B2 from the small diameter cylindrical portion 8B of the valve body 8 via the radial passage 8E, and the atmospheric pressure introduced into the variable pressure chamber B2 is connected to the tubular member 30. It is introduced into the variable pressure chamber A2 through the passage 32. As a result, a pressure difference is generated between the negative pressure chamber A1 and the variable pressure chamber A2, and between the negative pressure chamber B1 and the variable pressure chamber B2.

  For this reason, the valve body 8 is configured so that the thrust generated in the power piston 6 due to the pressure difference between the negative pressure chamber A1 and the variable pressure chamber A2 and the pressure piston 7 due to the pressure difference between the negative pressure chamber B1 and the variable pressure chamber B2. It moves forward to the master cylinder side (the left side in FIG. 1) with the thrust generated in. The thrust at this time is transmitted from the valve body 8 to the output rod 19 via the reaction disk 22, and the piston of the master cylinder connected to the output rod 19 is moved by the output rod 19 of the pneumatic booster 1 in the cylinder body. It is pushed in the axial direction.

  As a result, a brake fluid pressure corresponding to the stroke of the output rod 19 is generated in the cylinder body of the master cylinder, and this brake fluid pressure is applied to each wheel side wheel cylinder (is (Not shown). As a result, a braking force is applied to each wheel of the vehicle.

  On the other hand, when the brake operation is released, the input rod 10 is pushed back in the direction indicated by the arrow D by the return spring 13, and accordingly, the plunger 16 is pulled together with the moving body 17 in the same direction. At this time, the contact portion 16A of the plunger 16 is seated on the poppet valve body 11 and blocks the variable pressure chambers A2 and B2 from the outside atmosphere. However, since the plunger 16 presses the poppet valve body 11 in the arrow D direction against the weak spring 12 via the contact portion 16A, the poppet valve body 11 is moved from the valve seat portion 8G of the valve body 8. Take a seat away.

  As a result, the negative pressure chambers A1 and B1 and the variable pressure chambers A2 and B2 communicate with each other through the axial passage 8C, the radial passages 8D and 8E, and the negative pressure in the negative pressure chambers A1 and B1 is reduced. Introduced on the side of the variable room A2, B2. As a result, the pressure difference between the negative pressure chambers A1 and B1 and the variable pressure chambers A2 and B2 is lower than the pressure difference before the brake operation is released. Accordingly, the output rod 19 is pushed back together with the valve body 8 by the return spring 21 in the direction indicated by the arrow D, and finally the protruding end side of the stop key 18 comes into contact with the stepped portion 4C of the rear shell 4 as shown in FIG. .

  Then, with the stop key 18 in contact with the stepped portion 4C, the final return position of the plunger 16 is restricted, and the power pistons 6, 7, the valve body 8, the input rod 10, the output rod 19 and the like are shown in FIG. Return to the initial position. Further, the poppet valve body 11 is seated on the valve seat portion 8G of the valve body 8 and the contact portion 16A of the plunger 16, and the variable pressure chambers A2 and B2 are maintained in the negative pressure state similar to the negative pressure chambers A1 and B1. We will prepare for the next brake operation.

  By the way, in the pneumatic booster according to the prior art, the seat portion of the mounting member that supports the support plate and the shaft portion of the mounting member through which the tubular member is inserted are formed to have the same diameter. Therefore, if the shaft portion of the mounting member is made substantially the same as the outer diameter size of the vehicle body mounting bolt and the outer diameter size of the master cylinder mounting bolt in order to reduce the weight, a flange portion for receiving the support plate is required. Become. The outer diameter size of the flange portion must be larger than the outer diameter size of the shaft portion in order to support the support plate.

  In addition, each radial protrusion extending in the center direction of the through hole of the tubular member has a communication path communicating between the front chamber and the rear chamber in a state of being inserted into the shaft portion of the mounting member. In order to ensure, the front-end | tip is made into the position close | similar to the outer peripheral surface of a shaft part. Therefore, when each radial projection of the cylindrical member is projected toward the center direction of the through hole in accordance with the outer diameter of the shaft portion of the mounting member having a small diameter, the radial projection of the cylindrical member and the mounting member This causes a problem that the cylindrical member cannot be assembled to the mounting member.

  Therefore, the pneumatic booster 1 according to the present embodiment is reduced in weight by making the mounting member 24 as small as possible. That is, the outer diameter of the shaft portion 24A of the mounting member 24 is set to be substantially the same as the outer diameter of the vehicle body mounting bolt 24B and the outer diameter of the master cylinder mounting bolt 24C.

  The shaft portion 24A of the mounting member 24 is provided with a front flange portion 27 that supports the support plate 28 in the vicinity of the master cylinder mounting bolt 24C. Further, the front flange portion 27 is formed with three groove portions 27B that are spaced apart from each other in the circumferential direction. The three groove portions 27B are concave grooves that are recessed inward in the radial direction at positions corresponding to the three radial protrusions 30G of the cylindrical member 30, and are wider in the circumferential direction than the radial protrusion 30G. Is formed.

  Thereby, when the cylindrical member 30 is sub-assembled to the mounting member 24, the cylindrical member 30 is mounted in a state where the radial protrusion 30G of the cylindrical member 30 is aligned with the groove portion 27B of the front flange portion 27. The member 24 can be inserted from the master cylinder mounting bolt 24C side. As a result, the cylindrical member 30 can be easily assembled to the shaft portion 24A of the mounting member 24 having a small diameter, and the support plate 28 can be supported by the protruding portion 27A of the front flange portion 27. .

  Further, since the shaft portion 24A is made as small as possible, the inner diameter and the outer diameter of the cylindrical member 30 can be reduced. Accordingly, the mounting member 24 and the cylindrical member 30 can be reduced in weight, and the weight of the pneumatic booster 1 can be reduced.

  In the above-described embodiment, the case where the three groove portions 27B into which the three radial protrusions 30G of the cylindrical member 30 can be inserted is formed in the front flange portion 27 of the mounting member 24 as an example. did. However, the present invention is not limited to this. For example, the present invention may be configured as a first modification shown in FIGS. That is, as shown in FIG. 6, four groove portions 42A are formed in the front side flange portion 42 of the mounting member 41, and as shown in FIG. The radial protrusion 43A may be formed. In this case, the cylindrical member 43 can be easily assembled to the mounting member 41 by inserting each radial protrusion 43A through the groove 42A.

  Further, for example, as in the second modification shown in FIG. 8, the front side flange portion 52 of the mounting member 51 has a complementary shape with respect to the four radial protrusions 43A of the cylindrical member 43 shown in FIG. Four groove portions 52A may be formed.

  On the other hand, in the above-described embodiment, the case where the groove portion 27 </ b> B is formed in the front side flange portion 27 of the mounting member 24 has been described as an example. However, the present invention is not limited to this, and for example, a groove portion through which the radial projection of the cylindrical member can be inserted may be formed in the rear flange portion. The same applies to the first and second modified examples.

  Moreover, in embodiment mentioned above, the case where the radial direction protrusion 30G and the axial direction protrusion 30H of the cylindrical member 30 were integrally formed and demonstrated was mentioned as an example. However, the present invention is not limited to this, and for example, an axial protrusion that protrudes outward in the axial direction from the other end face of the cylindrical member may be provided separately from the radial protrusion. The same applies to the first and second modified examples.

1 Pneumatic booster 2 Housing 3 Front shell (first shell)
4 Rear shell (second shell)
5 Center shell (third shell)
24, 41, 51 Mounting member 24A Shaft portion 24B Car body mounting bolt (engagement portion)
24C Master cylinder mounting bolt (engagement part)
26 Rear side flange 27, 42, 52 Front side flange 27B, 42A, 52A Groove 30, 43 Cylindrical member 30F Through hole 30G, 43A Radial protrusion (protrusion)
32 Communication path A Front chamber B Rear chamber A1, B1 Negative pressure chamber A2, B2 Transformer chamber

Claims (1)

A third shell defining a plurality of chambers in a housing composed of a first shell and a second shell;
An attachment member provided through the first to third shells, and provided with an engaging portion that engages with the vehicle and the master cylinder at the end;
One end side is held by the third shell and is provided in one of the plurality of chambers, and has a through hole into which the mounting member is inserted, and the through hole communicates with the plurality of chambers. A cylindrical member serving as a communication path;
In a pneumatic booster comprising:
The tubular member is formed with a protrusion extending in the center direction of the through hole,
The mounting member is provided with flange portions that contact the first and second shells on the axially central side of the engaging portions, and at least one of the flange portions includes the cylinder. A pneumatic booster characterized in that a groove portion through which the protrusion of the shaped member can be inserted is formed.

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