JP4625519B2 - Negative pressure booster - Google Patents

Description

  The present invention relates to a negative pressure booster used for boosting operation of a brake master cylinder for a vehicle, and more particularly to an improvement of a negative pressure booster that allows a high output to be quickly exerted on an output rod during emergency braking.

To open the air introduction valve seat greatly during emergency braking and quickly introduce a large amount of air into the working chamber, and to make the output rod exhibit high output, slide the valve cylinder in its radial direction. It has already been known in Patent Document 1 that the connecting piece to be fitted is engaged with the valve piston at the time of emergency braking so as to keep the axial relative position of the valve piston with respect to the valve cylinder constant. It has been.
JP 2008-247376 A

  By the way, in what was disclosed by patent document 1, the perimeter of a connection piece is slidably contacted with the valve cylinder, the sliding area is large, the sliding resistance of a connection piece is large, and sliding of a connection piece is not smooth. Therefore, it is necessary to set the biasing force of the elastic member that biases the connecting piece inward along the radial direction of the valve cylinder.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a negative pressure booster capable of reducing the sliding resistance of the connecting piece and smoothing the sliding operation of the connecting piece.

  In order to achieve the above object, according to the first aspect of the present invention, a booster piston that divides the interior into a front negative pressure chamber and a rear working chamber connected to a negative pressure source is accommodated in the booster shell, A valve cylinder slidably supported on the rear wall of the booster shell is connected to the booster piston and linked to and connected to an input rod capable of moving back and forth, and forward from a predetermined retracted position with respect to the input piston. A valve piston that is fitted to the input piston and is elastically biased toward the retracted position, and the working chamber is moved to the negative pressure chamber according to the back-and-forth movement of the input rod. A control valve that communicates with the atmosphere is disposed in the valve cylinder, and engages with the valve piston during emergency braking in which the input piston and the valve piston advance forward by a predetermined stroke or more with respect to the valve cylinder. A connecting piece that maintains a constant axial relative position of the valve piston with respect to the valve cylinder is slidably fitted to the valve cylinder to enable movement along the radial direction of the valve cylinder, and the valve cylinder and the valve cylinder In a negative pressure booster provided with an elastic member between the connecting pieces for biasing the connecting piece inward along the radial direction of the valve cylinder, either the valve cylinder or the connecting piece includes the valve cylinder and A sliding protrusion is provided in contact with the other of the connecting pieces to guide the sliding operation of the connecting piece.

  The invention according to claim 2 is characterized in that, in addition to the configuration of the invention according to claim 1, the hardness of the sliding projection is set lower than the hardness of the other of the valve cylinder and the connecting piece. To do.

  Furthermore, in the invention described in claim 3, in addition to the structure of the invention described in claim 1 or 2, a plurality of the sliding protrusions are slid on one of the opposing surfaces of the connecting piece and the valve cylinder. It is characterized by projecting so as to extend parallel to the moving direction.

  According to the first aspect of the present invention, since the sliding protrusion provided on one of the valve cylinder and the connecting piece abuts on the other of the valve cylinder and the connecting piece, the sliding operation of the connecting piece is guided. It is possible to reduce the sliding resistance by reducing the sliding contact area of the piece with the valve cylinder, to facilitate the sliding operation of the connecting piece, and to set the biasing force of the elastic member to be relatively small.

  According to the second aspect of the invention, since the hardness of the sliding projection is lower than the hardness on the side where the sliding projection is brought into sliding contact, wear due to sliding of the connecting piece is likely to occur on the sliding projection side. Further, the sliding protrusion can be prevented from biting into the side where the sliding protrusion is brought into sliding contact with the sliding protrusion, and a twisting can be prevented, and a stable sliding operation of the connecting piece can be ensured.

  Furthermore, since the sliding protrusion extends parallel to the sliding direction of the connecting piece, the sliding of the connecting piece can be stably guided while reducing the sliding area.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  1 to 11 show a first embodiment of the present invention, FIG. 1 is a longitudinal sectional view of a negative pressure booster, and FIG. 2 is a diagram of 2 in FIG. 1 when the negative pressure booster is in an inoperative state. 3 is a cross-sectional view taken along line 2-2 in FIG. 3, FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. 2, FIG. 4 is a cross-sectional view taken along line 4-4 in FIG. 5 is a sectional view taken along line 6-6 of FIG. 2, FIG. 7 is a perspective view of the elastic member and the connecting piece, FIG. 8 is a sectional view corresponding to FIG. 2 in a normal brake state, and FIG. FIG. 10 is a cross-sectional view corresponding to FIG. 2 in an emergency brake state, and FIG. 11 is a cross-sectional view corresponding to FIG. 2 in an emergency brake release state.

  First, in FIG. 1, a booster shell 11 of a negative pressure booster B is constituted by connecting opposite ends of a front shell half body 11a and a rear shell half body 11b to each other, and the rear shell half body 11b is arranged in front of a vehicle compartment. The cylinder body Ma of the brake master cylinder M operated by the booster B is fixed to the front shell half body 11 a by bolts 14.

  The inside of the booster shell 11 is formed in an annular shape with a steel plate and is accommodated in the booster shell 11 so as to be capable of reciprocating back and forth. A diaphragm 16 whose outer peripheral edge is sandwiched between the bodies 11a and 11b is divided into a negative pressure chamber 17 on the front side and a working chamber 18 on the rear side. The negative pressure chamber 17 is connected via a negative pressure introduction pipe 19. To the negative pressure source V (for example, inside the intake manifold of the internal combustion engine). A synthetic resin valve cylinder 20 </ b> A is integrally coupled to the central portions of the booster piston 15 and the diaphragm 16.

  Referring also to FIG. 2, the valve cylinder 20 </ b> A is slidable via a bearing member 22 and a seal member 23 on a guide cylinder portion 21 that protrudes from the center portion of the rear shell half 11 b and extends rearward. Supported.

  In the valve cylinder 20A, an input piston 25, an input rod 26 connected to the input piston 25, and the working chamber 18 are switched between the negative pressure chamber 17 and the atmosphere according to the back and forth movement of the input rod 26. A control valve 27 is provided.

  In the central portion of the valve cylinder 20A, a cylinder hole 28 having a front end opened forward and a receiving hole 29 connected coaxially to the rear end of the cylinder hole 28 are provided coaxially from the front. An annular stepped portion 30 is formed between the rear end of the cylinder hole 28 and the front end of the accommodation hole 29 so as to face the rear.

  The input piston 25 has a piston rear portion 25a, a piston front portion 25b having a smaller diameter than the piston rear portion 25a, and a neck portion 25c that has a smaller diameter than the piston front portion 25b and connects the piston rear portion 25a and the piston front portion 25b. And a flange portion 25d that projects outward in the radial direction is integrally provided at the front end of the piston rear portion 25a. Thus, the piston front portion 25b is slidably fitted into the cylinder hole 28 of the valve cylinder 20A, and the piston rear portion 25a and the flange portion 25d are accommodated coaxially in the accommodation hole 29 of the valve cylinder 20A. In addition, a plurality of, for example, four guide protrusions 29a opposed to the outer periphery of the flange portion 25d protrude at the front end of the receiving hole 29 toward the radially inward direction as shown in FIGS. Established.

  A connecting tube portion 25e is coaxially and integrally formed at the rear end of the piston rear portion 25a. A spherical front end portion 26a of the input rod 26 is fitted into the connecting tube portion 25e, and the spherical front end portion 26a is removed. A part of the connecting cylinder part 25e is caulked for stopping. Thereby, the input rod 26 is connected to the input piston 25 so as to be able to swing, and a brake pedal P (see FIG. 1) for operating the input rod 26 is connected to the rear end of the input rod 26.

  A cylindrical valve piston 34 is fitted on the outer periphery of the piston rear portion 25a of the input piston 25 so as to be able to slide between the retracted position and the advanced position, and the retracted position is shown in FIG. 34 is defined by being received by a retaining ring 36 locked to the outer periphery of the rear end portion of the connecting cylinder portion 25e, and the forward position of the valve piston 34 is determined by the front end of the valve piston 34 being a flange of the input piston 25. It is defined by contacting the part 25d. An annular seal member 37 slidably contacting the inner periphery of the valve piston 34 is mounted on the outer peripheral surface of the piston rear portion 25a.

  The valve piston 34 is provided with an annular recess 35 having a front end opened coaxially, and a part of the input piston 25 between the flange portion 25d and the valve piston 34 is accommodated in the recess 35. A spring 38 is retracted to bias the valve piston 34 toward the retracted position.

  An air introduction valve seat 39 is formed at the rear end of the valve piston 34, and an annular negative pressure introduction valve seat 40 arranged concentrically so as to surround the air introduction valve seat 39 is formed in the valve cylinder 20A.

  Further, a common valve body 41 that cooperates with the air introduction valve seat 39 and the negative pressure introduction valve seat 40 is attached to the valve cylinder 20A. The valve body 41 is entirely formed of an elastic material such as rubber, and includes a valve portion 41a disposed so as to face the atmosphere introduction valve seat 39 and the negative pressure introduction valve seat 40, and a valve portion 41a. The telescopic cylinder part 41b is connected to the inner periphery and extends rearward, and the annular mounting bead part 41c is connected to the rear end of the telescopic cylinder part 41b. The annular part is inserted into the valve part 41a from the inner peripheral side. The reinforcing plate 42 is molded and joined to the valve portion 41a. An annular seal lip 43 bent rearward is integrally formed on the outer periphery of the valve portion 41a.

  The mounting bead portion 41c is formed between the rear valve holder 45 and the front valve holder 44 that contacts the rear end of the annular ridge 81 formed integrally with the negative pressure introduction valve seat 40 on the inner peripheral side of the valve cylinder 20A. The rear valve holder 45 is fitted with a sealing member 46 such as an O-ring that is in close contact with the inner peripheral surface of the valve cylinder 20A.

  Between the reinforcing plate 42 molded to the valve portion 41a and the input rod 26, there is a valve spring 47 that urges the valve portion 41a in the direction to seat the air introduction valve seat 39 and the negative pressure introduction valve seat 40. It is reduced. Thus, the negative pressure introduction valve seat 40, the atmosphere introduction valve seat 39, the valve body 41 and the valve spring 47 constitute a control valve 27.

  An input return spring 48 is contracted between the rear valve holder 45 and the input rod 26, so that the front and rear valve holders 44 and 45 abut against the rear end of the annular raised portion 81 of the valve cylinder 20A. While being held, the input rod 26 is urged in the backward direction.

  A front annular chamber 49 surrounding the negative pressure introducing valve seat 40 is formed in the annular raised portion 81 on the inner periphery of the valve cylinder 20 </ b> A, and the front surface of the valve portion 41 a faces the front annular chamber 49. The inner peripheral surface on the radially outer side of the front annular chamber 49 extends rearward from the negative pressure introducing valve seat 40, and the seal lip 43 on the outer periphery of the valve portion 41a is slidably in close contact with the inner peripheral surface. Accordingly, the front annular chamber 49 is closed when the valve portion 41 a is seated on the negative pressure introducing valve seat 40. Further, a rear annular chamber 50 isolated from the front annular chamber 49 is defined inside the annular raised portion 81 by a valve portion 41a with a seal lip 43 so as to face the back surface of the valve portion 41a. .

  The valve cylinder 20A includes a plurality of first ports 51 formed so that one end communicates with the negative pressure chamber 17 and the other end opens into the front annular chamber 49, and one end communicates with the working chamber 18 and the other end. Is provided with a second port 52 formed so as to open between the negative pressure introduction valve seat 40 and the atmospheric introduction valve seat 39.

  3, 4, and 5, the second port 52 is formed to have a diameter larger than that of the cylinder hole 28, is coaxially connected to the rear end of the cylinder hole 28, and is connected to the piston rear portion 25 a of the input piston 25 and the valve. An accommodation hole 29 provided in the valve cylinder 20A so as to accommodate the piston 34, and one end communicating with the working chamber 18 and the other end communicating with the front end of the accommodation hole 29 are provided on one diameter line of the valve cylinder 20A. The radial communication holes 54, that is, the second port 52 extends in a direction parallel to the axis of the valve cylinder 20A and is provided in the valve cylinder 20A. It communicates with the rear annular chamber 50 through the holes 55.

  Both ends of a stretchable boot 58 covering the valve cylinder 20A are attached to the rear end of the guide cylinder portion 21 of the rear shell half 11b in the booster shell 11 and the input rod 26, and the rear end of the boot 58 An air introduction port 59 communicating with the inside of the valve body 41 is provided in the part. A filter 60 for filtering the air flowing into the atmosphere introduction port 59 is interposed between the outer peripheral surface of the input rod 26 and the rear inner peripheral surface of the valve cylinder 20A. The filter 60 is connected to the input rod 26 and the valve cylinder 20A. It has flexibility so as not to inhibit relative movement.

  A key 61 that defines the backward limit of the booster piston 15 and the input piston 25 is attached to the valve cylinder 20A. As shown in FIG. 4, the key 61 includes a pair of restricting portions 61a and 61a that are inserted into the radial communication holes 54 and 54 of the valve cylinder 20A so as to sandwich the neck portion 25c of the input piston 25 from both sides. A stopper wall 62 provided integrally with the guide cylinder portion 21 of the rear shell half 11b, which is integrally formed with a connecting portion 61b that connects one end of the restricting portion 61a ... and is formed in a substantially U shape. It arrange | positions so that it may oppose the front surface of. Thus, when the key 61 abuts against the stopper wall 62, the backward limit of the booster piston 15 and the valve cylinder 20A is defined, and when the front end surface of the neck portion 25c of the input piston 25 abuts against the key 61, the input piston 25 And the backward limit of the input rod 26 is defined. The axial length of the neck portion 25c is set to be larger than the plate thickness of the key 61 so that the input piston 25 and the key 61 can be slightly moved relative to each other.

  The front end surface of the radial communication hole 54 along the axial direction of the valve cylinder 20A is continuous with the step portion 30 between the cylinder hole 28 and the accommodation hole 29, and the valve cylinder 20A includes the radius Projections 63 projecting rearward from the front end face of the direction communication holes 54 are integrally projected so as to be located at the center of the radial communication holes 54 along the circumferential direction of the valve cylinder 20A. The key 61 is inserted into the radial communication hole 54 with the protrusions 63 sandwiched between the pair of restricting portions 61a and 61a.

  Connecting pieces 65A, 65A that allow movement along the radial direction of the valve cylinder 20A are slidably fitted at a plurality of locations in the circumferential direction of the valve cylinder 20A. The connecting pieces 65A are slidably fitted into the radial communication holes 54 arranged at two positions spaced equally in the circumferential direction of the cylinder 20A.

  Referring to FIGS. 6 and 7 together, the connecting piece 65A includes a rear arm portion 65a and a front arm portion 65b that are arranged at intervals along the axial direction of the valve cylinder 20A, and a radius of the valve cylinder 20A. A connecting portion 65c that connects between the outer ends of the rear arm portion 65a and the front arm portion 65b along the direction is integrally formed, and has a substantially U shape that opens toward the radially inner side of the valve cylinder 20A. It is formed.

  The connecting piece 65A has a rear arm portion 65a opposed to a rear end surface of the radial communication hole 54 along the axial direction of the valve cylinder 20A, and a front arm portion 65b opposed to the protrusion 63 so as to communicate with the radial direction. It is slidably fitted into the hole 54, and both side surfaces of the connecting piece 65 </ b> A along the circumferential direction of the valve cylinder 20 </ b> A are in sliding contact with the inner surface of the radial communication hole 54. That is, the connecting piece 65A is slidably fitted into the radial communication hole 54 while being capable of slight axial relative movement with respect to the valve cylinder 20A while being prevented from relative movement in the circumferential direction with respect to the valve cylinder 20A.

  Between the connecting piece 65A and the valve cylinder 20A, an elastic member 66 that elastically urges the connecting pieces 65A toward the valve piston 34 on the inner side along the radial direction of the valve cylinder 20A. Is installed. The elastic member 66 is disposed on both sides of the restricting portions 61a in parallel with the step portion 30 of the valve cylinder 20A and the pair of restricting portions 61a, 61a of the key 61, and the step portion 31 of the valve cylinder 20A. And a pair of support portions 66a, 66a, and a pressing portion 66b connected to the outer ends of the support portions 66a along the radial direction of the valve cylinder 20A. The inner ends of the support portions 66a are engaged with the inner periphery of the receiving hole 29, and the pressing portion 66b is formed in a substantially U shape that opens forward, and the support portions 66a. It extends rearward from the outer end of.

  The rear part of the pressing part 66b of the elastic member 66 is brought into contact with the connecting part 65c of the connecting piece 65A, so that the connecting piece 65A is elastically biased toward the valve piston 34 side. Engaging portions 67 are provided at the inner ends of the rear arm portions 65a in 65A. On the other hand, on the outer periphery of the valve piston 34, an annular locking portion 68 capable of engaging the engaging portions 67 from the rear side and the engaging portion 67 are slidably contacted with each other. An annular sliding contact surface 69 disposed in front of 68 is provided.

  Thus, the engaging portion 68 engages the engaging portions 67 of the connecting piece 65A at the time of emergency braking in which the input piston 25 and the valve piston 34 advance ahead of the valve cylinder 20A by a predetermined stroke or more. In the state where the axial position of the valve piston 34 relative to the valve cylinder 20A is kept constant, the valve piston 34 is provided on the outer periphery of the valve piston 34, and the engagement portions 67 are engaged with the locking portions 68. The piston 34 is connected to the valve cylinder 20A so as to be substantially fixed. Further, the sliding surface 69 is formed on the outer periphery of the valve piston 34 so that the engaging portions 67 are in sliding contact during non-emergency braking.

  On the inner end portion of the front arm portion 65b ... in the connecting piece 65A ..., an inclined surface 70 ... is formed so as to face the front so as to become an outward position along the radial direction of the valve cylinder 20A. The On the other hand, the flange portion 25d provided on the input piston 25 is located in front of the inclined surface 70 in the brake operating state, and responds to the backward movement of the input piston 25 relative to the valve piston 34 when the emergency brake is released. Then, the connecting pieces 65A are moved radially outward of the valve cylinder 20A so as to contact the inclined surfaces 70 and disengage the engaging portions 67 from the locking portions 68.

  Further, the connecting piece 65A is urged to receive the elastic force from the elastic members 66, and the connecting piece 65A is urged radially inward and forward or backward in the axial direction of the valve cylinder 20A. Thus, a pressure receiving surface 71 is provided for contacting the elastic member 66. Thus, in this embodiment, the rear portions of the pressing portions 66b of the elastic members 66 are in contact with the rear portions of the connecting portions 65c of the connecting pieces 65A, and the rear portions of the connecting portions 65c are rearward. The pressure receiving surfaces 71... Are inclined so as to be separated from the axis of the valve cylinder 20 </ b> A, and the connecting portions 65 </ b> A... Are brought into contact with the pressure receiving surfaces 71. The valve barrel 20A is biased radially inward and axially forward.

  Thus, the resilient force of the elastic members 66 ... biases the connecting pieces 65A ... inward in the radial direction of the valve cylinder 20A and also urges backward in the axial direction of the valve cylinder 20A. Therefore, it is possible to prevent the connecting pieces 65A from rattling in the axial direction of the valve cylinder 20A. As a result, it is possible to ensure smooth operation of the connecting pieces 65A, and to stabilize the brake assist characteristics.

  Further, the valve cylinder 20A is restricted between the rear arm part 65a and the front arm part 65b so as to face the connection parts 65c of the connection piece 65A ... from the inside along the radial direction of the valve cylinder 20A. .. Are integrally provided so as to connect the side walls of the radial communication holes 54. The restricting portions 72 serve to prevent the connecting pieces 65A urged by the elastic members 66 during assembly from entering the receiving hole 29.

  The valve cylinder 20A is provided with sliding protrusions 85, 85,... 86 that contact the connecting piece 65A and guide the sliding operation of the connecting piece 65A. Thus, the pair of sliding protrusions 85, 85 are projected from the inner surface of the radial communication hole 54 so as to be in sliding contact with the rear surface of the connecting piece 65A in the radial communication hole 54. These are arranged so as to extend in parallel along the radial direction of the valve cylinder 20A. Further, the sliding protrusion 86 can slide on the front surface of the connecting piece 65A in the radial communication hole 54 with the protrusion 63 protruding rearward from the front end face of the radial communication hole 54. Projected.

  In addition, the hardness of the sliding protrusions 85, 85,... 86 is set lower than the hardness of the connecting piece 65A, which is the side in which the sliding protrusions 85, 85,. In the first embodiment, the valve cylinder 20A is a synthetic resin such as polybutylene terephthalate resin (PBT), while the connecting piece 65A is a synthetic resin having a hardness higher than that of the valve cylinder 20B. For example, it is made of polyphthalamide resin (PPA).

  In FIG. 2 again, an annular portion 82 surrounding the cylinder hole 28 is formed on the front end surface of the valve cylinder 20A, and a cup-shaped output piston 75 is slidably fitted to the outer periphery of the annular portion 82. A flat elastic reaction force piston 76 is interposed between axially opposed surfaces of the output piston 75 and the annular portion 82 and the piston front portion 25b of the input piston 25.

  At that time, the elastic reaction force piston 76 is in close contact with the front end face of the annular portion 82. Further, a constant gap g is formed between the piston front portion 25b of the input piston 25 and the elastic reaction force piston 76 when the negative pressure booster B is not operated.

  An output rod 77 projects from the front surface of the output piston 75 and is connected to the piston 13 of the brake master cylinder M.

  Thus, the annular portion 82 of the valve cylinder 20A, the input piston 25, the elastic reaction force piston 76, and the output piston 75 are connected to the booster piston 15 due to the difference in atmospheric pressure between the input to the input rod 26 and the working chamber 18 and the negative pressure chamber 17. A reaction force mechanism 73 that transmits the resultant force to the output rod 77 is configured.

  A retainer 78 is disposed in contact with the output piston 75 and the front end face of the valve cylinder 20A, and the booster piston 15 and the valve cylinder 20A are urged in the backward direction between the retainer 78 and the front wall of the booster shell 11. The booster return spring 79 is contracted.

  Next, the operation of the first embodiment will be described. In the resting state of the negative pressure booster B, as shown in FIGS. 1 and 2, the key 61 attached to the valve cylinder 20A is moved to the rear shell half body 11b. The front end surface of the neck portion 25c of the input piston 25 is brought into contact with the key 61, so that the booster piston 15 and the input rod 26 are positioned in the respective retreat limits. At this time, the valve piston 34 is held in a retracted position in contact with the retaining ring 36 on the input piston 25 by the urging force of the set spring 38, and the atmosphere introduction valve seat 39 at the rear end of the valve piston 34 is a valve body 41. While seated on the valve portion 41 a, the valve portion 41 a is pressed to be slightly separated from the negative pressure introduction valve seat 40. As a result, communication between the air introduction port 59 and the second port 52 is blocked, and communication between the first and second ports 51 and 52 is established. Therefore, the negative pressure in the negative pressure chamber 17 is transmitted to the working chamber 18 through both ports 51 and 52, and both the chambers 17 and 18 are at the same pressure, so that the booster piston 15 and the valve cylinder 20A are provided with a booster return spring 79. It is held in the retracted position by the force.

  [Normal Brake] When the brake pedal P is depressed at a normal speed to brake the vehicle and the input rod 26 and the input piston 25 are advanced, the input piston 25 is held in the retracted position as shown in FIG. Advance with the valve piston 34 in the state. Therefore, the urging force of the valve spring 47 causes the valve body 41 to immediately seat the valve part 41a on the negative pressure introduction valve seat 40 while extending the expansion / contraction cylinder part 41b. The communication between the first and second ports 51, 52 is blocked by moving away from the second port 52, and the second port 52 communicates with the atmosphere introduction port 59 through the inside of the valve body 41.

  As a result, the atmosphere flowing into the valve cylinder 20A from the atmosphere introduction port 59 passes through the atmosphere introduction valve seat 39 and is introduced into the working chamber 18 through the second port 52, and the working chamber 18 is set to a higher pressure than the negative pressure chamber 17. Therefore, the forward thrust based on the pressure difference between them is obtained, and the booster piston 15 moves forward against the force of the booster return spring 79 with the valve cylinder 20A, the elastic reaction force piston 76, the output piston 75 and the output rod 77. Then, the piston 13 of the brake master cylinder M is pressed forward by the output rod 77. As described above, the air introduction valve seat 39 moves forward simultaneously with the advancement of the input rod 26 and is separated from the valve portion 41a, whereby the responsiveness of the booster piston 15 can be enhanced.

  Even if the atmosphere introduction valve seat 39 is opened until the piston front part 25b of the input piston 25 closes the gap g and abuts against the elastic reaction force piston 76 in the early stage of the input rod 26, the input rod 26 remains in the reaction force mechanism 73. Therefore, the output of the output rod 77 shows a jumping characteristic that rises rapidly as indicated by a line ab in FIG.

  Further, during the forward operation of the input rod 26, the negative pressure transmitted from the first port 51 to the front annular chamber 49 acts on the front surface of the valve portion 41a facing the front annular chamber 49 of the valve cylinder 20A. Since the atmospheric pressure transmitted from the second port 52 to the rear annular chamber 50 via the axial communication hole 55 acts on the back surface of the valve portion 41a facing the rear annular chamber 50 of the valve cylinder 20A, the valve portion 41a Further, in addition to the set load of the valve spring 47, it is also urged in the seating direction with the negative pressure introducing valve seat 40 by a pressure difference between the front and rear annular chambers 49, 50. Therefore, it is possible to reduce the set load of the valve spring 47 by the biasing force due to the pressure difference, and accordingly, it is possible to reduce the set load of the input return spring 48 that biases the input rod 26 in the backward direction. As a result, jumping characteristics can be obtained with a relatively small initial operation input, so that the invalid strokes of the brake master cylinder M and each wheel brake can be quickly eliminated, and the responsiveness of each wheel brake can be enhanced.

  Further, in this state, the seal lip 43 on the outer periphery of the valve portion 41a is bent rearward and is in close contact with the inner peripheral surface of the valve cylinder 20A, so that the pressure difference between the front and rear annular chambers 49 and 50 is caused. The contact force to the inner peripheral surface is increased, and the airtightness between the annular chambers 49 and 50 can be ensured.

  After the piston front portion 25 b of the input piston 25 comes into contact with the elastic reaction force piston 76, a part of the operation reaction force of the output rod 77 is fed back to the input rod 26 via the elastic reaction force piston 76. Therefore, the operator can perceive the magnitude of the output of the output rod 77.

  If the advancement of the input rod 26 is stopped when the desired output is obtained, the advancement of the booster piston 15 causes the valve portion 41a of the valve body 41 to be seated on the atmosphere introduction valve seat 39 again, and the negative pressure of the atmosphere beyond that is increased. It stops by preventing the introduction to the chamber 3. Accordingly, the valve cylinder 20A and the booster piston 15 advance in accordance with the advance of the input rod 26.

  By the way, at the time of normal braking where the forward speed of the input rod 26 is relatively low, the follow-up delay of the booster piston 15 and the valve cylinder 20A with respect to the input rod 26 is relatively small, so that the relative displacement of the input rod 26 and the valve cylinder 20A is small. The relative displacement between the valve piston 34 that moves forward together with the input piston 25 connected to the input rod 26 and the connecting piece 65A slidably fitted to the valve cylinder 20A is also small. Therefore, the engaging portions 67 of the connecting pieces 65A are merely in sliding contact with the sliding contact surface 69 of the valve piston 34 and are not engaged with the locking portion 68.

  The output of the output rod 77 has a boost ratio determined by the ratio of the pressure-receiving area of the annular portion 82 of the valve cylinder 20A that contacts the elastic reaction force piston 76 and the piston front portion 25a of the input piston 25. Increase as shown by c.

  After reaching the boost limit point c at which the pressure difference between the negative pressure chamber 17 and the working chamber 18 reaches the maximum, the output of the output rod 77 is equal to the pressure difference of the booster piston 15 as indicated by the line cd. Is the sum of the maximum thrust by and the operation input to the input rod 26.

  [Emergency Brake] At the time of emergency braking in which the brake pedal P is depressed rapidly, the input piston 25 advances at a high speed. Therefore, before the booster piston 15 and the valve cylinder 20A start to advance, the piston front portion 25b of the input piston 25 is elastically reacted. The input piston 25 and the valve piston 34 are greatly advanced while compressing the force piston 76. Then, as shown in FIG. 10, the engaging portions 67 of the connecting pieces 65A are engaged with the engaging portions 68 of the valve piston 34, and the valve piston 34 resists the urging force of the set spring 38 and The connecting piece 65A slidably fitted to 20A is connected, and the valve piston 34, the input piston 25, and the valve cylinder 20A are substantially integrated, and the air introduction valve seat 39 is the valve body. The valve portion 41a of the 41 is kept in the fully open state that is separated to the maximum.

  Thus, during emergency braking, the valve piston 34 is connected to the connecting piece 65A... And the valve cylinder 20A at the connecting point e shown in FIG. Even if the valve cylinder 20A advances slightly so as to follow the advance of the input rod 26, the valve piston 34 moves forward together with the valve cylinder 20A, so that the fully open state of the air introduction valve seat 39 is maintained. Is done. As a result, a large amount of air is introduced into the negative pressure chamber 17 at a stretch, and as indicated by a line ef in FIG. 9, at the boost limit point f at which the pressure difference between the negative pressure chamber 17 and the working chamber 18 becomes maximum. It reaches immediately and can increase the output by ΔP compared to the normal braking, and can keep pressing the piston 13 of the master cylinder M strongly and can respond quickly to emergency braking.

  Even during this emergency braking, the air introduction valve seat 39 can move forward simultaneously with the advancement of the input rod 26 and can be separated from the valve portion 41a, so that the response of the booster piston 15 can be enhanced.

  Further, in the state where the valve piston 34 and the valve cylinder 20A are connected via the connecting piece 65A, the spring load of the set spring 38 provided between the input piston 25 and the valve piston 34 acts on the input piston 25 in the forward direction. Therefore, the brake operation force at the time of emergency braking can be reduced.

  Further, the amount of preceding stroke in the forward direction of the input piston 25 with respect to the valve cylinder 20A necessary for engaging the engaging portions 67 of the connecting piece 65A with the locking portion 68 of the valve piston 34 is determined by the amount of the input piston 25. The dimensions of the connecting pieces 65A along the axial direction can be changed, and the brake assist start threshold during emergency braking can be easily adjusted by changing the dimensions of the connecting pieces 65A.

  [Release from Emergency Brake State] When the pedaling force is released from the brake pedal P to release the emergency brake state, first, the input rod 26 and the input piston 25 are moved backward by the force of the input return spring 48. When the input piston 25 starts retreating, as shown in FIG. 11, the flange portion 25d of the input piston 25 comes into contact with the inclined surface 70 of the connecting piece 65A, so that the connecting piece 65A is detached from the locking portion 68. Since the connecting pieces 65A are spread so as to cause the connecting pieces 65A, the engagement state of the connecting pieces 65A to the valve piston 34 is released. Thereafter, the valve piston 34 immediately returns to the retracted position in contact with the retaining ring 36 of the input piston 25 by the urging force of the set spring 38, and the air introduction valve seat 39 is seated on the valve portion 41 a of the valve body 41. Since the valve portion 41a is pushed rearward to be separated from the negative pressure introduction valve seat 40, the working chamber 18 communicates with the negative pressure chamber 17 via the second port 52 and the first port 51, and is connected to the working chamber 18. While the introduction of the atmosphere is blocked, the air in the working chamber 18 is sucked into the negative pressure source V through the negative pressure chamber 17 and the pressure difference between them is eliminated. As a result, the booster piston 15 is also retracted by the resilient force of the booster return spring 79 and the operation of the master cylinder M is released.

  Moreover, the stroke amount in the reverse direction of the input piston 25 until the emergency brake is released can be changed by changing the dimension of the connecting piece 65A along the axial direction of the input piston 25. Can be easily adjusted by changing the dimensions of the connecting piece.

  In addition, the sliding protrusions 85, 85,... 86 provided on the valve cylinder 20A are in contact with the connecting pieces 65A, so that the sliding operation of the connecting pieces 65A is guided. The sliding contact area with respect to 20A can be reduced to reduce the sliding resistance, the sliding operation of the connecting piece 65A can be smoothed, and the biasing force of the elastic member 66 can be set to be relatively small. Become.

  Further, since the hardness of the sliding projections 85, 85,... 86 is lower than the hardness of the connecting piece 65A that makes the sliding projections 85, 85,. Wear tends to occur on the sliding projections 85, 85,..., 86 side, preventing the sliding projections 85, 85,... It is possible to ensure a stable sliding operation.

  Further, since the pair of sliding protrusions 85 and 85 slidably in contact with the rear surface of the connecting piece 85A is provided in the valve cylinder 20A so as to extend in parallel along the radial direction of the valve cylinder 20A, the sliding area is further increased. It is possible to stably guide the sliding of the connecting piece 65A while reducing the size.

  The valve cylinder 20A is made of synthetic resin, and the connecting pieces 65A are made of metal, so that the hardness of the sliding projections 85, 85,... 86 is set lower than the hardness of the connecting pieces 65A. It may be.

  FIG. 12 shows a second embodiment of the present invention, and sliding protrusions 65d, 65d, 65e may be provided on the connecting piece 65B. That is, the connecting piece 65B is slidably fitted into the radial communication hole 54 (see the first embodiment) of the valve cylinder 20A in the same manner as in the first embodiment. Similarly to the connection piece 65A of the first embodiment, the rear piece 65a, the front arm part 65b, and the connection part 65c are integrally formed, and the radial communication hole 54 is formed on the rear surface of the connection piece 65B. A pair of sliding protrusions 65d, 65d that can come into sliding contact with the inner surface of the valve cylinder 20A are integrally projected so as to extend in parallel with the radial direction of the valve cylinder 20A. A sliding projection 65e that can be brought into sliding contact with the rear surface of the projection 63 (see the first embodiment) is integrally projected so as to extend in the radial direction of the valve cylinder 20A.

  In addition, the hardness of the sliding protrusions 65d, 65d, 65e is set lower than the hardness of the valve cylinder 20A in which the sliding protrusions 65d, 65d, 65e are slidably contacted. In the embodiment, the valve cylinder 20A is made of, for example, polyphthalamide resin (PPA), whereas the connecting piece 65B is made of a synthetic resin having a hardness lower than that of the valve cylinder 20A, such as polybutylene terephthalate resin (PBT). It is made of synthetic resin.

  The same effect as that of the first embodiment can also be achieved by the second embodiment.

  FIGS. 13 to 16 show a third embodiment of the present invention. FIG. 13 is a cross-sectional view corresponding to FIG. 2 when the negative pressure booster is in an inoperative state, and FIG. FIG. 15 is a sectional view taken along line -14, FIG. 15 is a sectional view taken along line 15-15 in FIG. 13, and FIG. 16 is a perspective view showing the relative arrangement of the elastic member and the connecting piece.

  Note that portions corresponding to those of the first embodiment are only denoted by the same reference numerals and are not illustrated in detail.

  The valve cylinder 20B is slidably supported through the bearing member 87 and the seal member 23 on the guide cylinder portion 21 that protrudes from the center portion of the rear shell half 11b and extends rearward. The valve cylinder 20B has an annular raised portion 81 and an annular portion 82 and is formed in a shape similar to the valve cylinder 20A of the first embodiment, and the like in the circumferential direction of the valve cylinder 20B. The connecting pieces 91 are slidably fitted in the radial communication holes 54 provided at two intervals.

  The front end surface of the radial communication hole 54 along the axial direction of the valve cylinder 20B is continuous with the stepped portion 30 between the cylinder hole 28 and the accommodation hole 29, and the valve cylinder 20B includes the radius Projections 93 projecting rearward from the front end face of the direction communication holes 54 are integrally projected so as to be located at the center of the radial communication holes 54 along the circumferential direction of the valve cylinder 20B. The key 61 is inserted into the radial communication hole 54 so as to sandwich the protrusions 93 between the pair of restricting portions 61a and 61a. Moreover, restricting portions 93a projecting rearward are integrally provided at the inner ends of the projecting portions 93 along the radial direction of the valve cylinder 20B.

  The connecting piece 91 includes a rear arm portion 91a and a front arm portion 91b arranged at intervals along the axial direction of the valve cylinder 20B, and the rear arm portion 91a and the front arm along the radial direction of the valve cylinder 20B. A connecting portion 91c that connects the outer ends of the portion 91b is integrally formed, and is formed in a substantially U shape that is open toward the inside in the radial direction of the valve cylinder 20B.

  The connecting piece 91 has the rear arm portion 91a opposed to the rear end surface of the radial communication hole 54 along the axial direction of the valve cylinder 20B and the radial arm communication with the front arm portion 91b opposed to the protrusion 93. The front arm portion 91b is provided with a recess 94 that is slidably fitted into the hole 54 and into which the restriction portion 93a is inserted.

  Both side surfaces of the connecting piece 91 along the circumferential direction of the valve cylinder 20B are in sliding contact with the inner surface of the radial communication hole 54, and the connecting piece 91 is a valve that prevents relative movement in the circumferential direction with respect to the valve cylinder 20B. A slight axial relative movement with respect to the cylinder 20 </ b> B is possible, and is slidably fitted into the radial communication hole 54.

  Between the connecting pieces 91 and the valve cylinder 20B, there is an elastic member 92 that elastically urges each connecting piece 91 toward the valve piston 34 side on the inner side along the radial direction of the valve cylinder 20B. It is installed. The elastic member 92 is formed in an arc shape in common to the pair of connecting pieces 91, 91, and is provided on the outer periphery of the valve cylinder 20B corresponding to the outer end opening of the radial communication hole 54. The mounting groove 95 is mounted. In addition, the valve cylinder 20B is provided with a detent 100 that abuts both ends of the elastic member 92 in the circumferential direction and restricts the circumferential movement of the elastic member 92, and the mounting groove 95 is formed on the outer periphery of the valve cylinder 20B. The rotation stopper 100 provided is formed in an arc shape so as to be sandwiched between both ends in the circumferential direction.

  When the elastic member 92 abuts on the connecting portion 91c of the connecting piece 91, the connecting piece 91 is elastically biased toward the valve piston 34, and the rear arm portion 91a of the connecting piece 91 ... At the inner end portion, there are provided engaging portions 97... Which can be engaged from the rear side with an annular locking portion 68 provided on the outer periphery of the valve piston 34, and the engaging portions 97. It can be slidably contacted with a slidable contact surface 69 which is disposed in front of the portion 68 and provided on the outer periphery of the valve piston 34.

  Thus, the engaging portion 68 engages the engaging portions 97 of the connecting pieces 91 at the time of emergency braking in which the input piston 25 and the valve piston 34 advance ahead of the valve cylinder 20B by a predetermined stroke or more. In this state, the axial relative position of the valve piston 34 with respect to the valve cylinder 20B is kept constant, and the valve piston 34 is substantially fixed to the valve cylinder 20B in a state where the engaging portions 97. To be connected. Further, during non-emergency braking, the engaging portions 97 are in sliding contact with the sliding contact surface 69.

  In the inner end portion of the front arm portion 91b of the connecting piece 91, an inclined surface 98 is formed so as to face the front as it goes forward and along the radial direction of the valve cylinder 20B. . On the other hand, the flange portion 25d provided on the input piston 25 is located in front of the inclined surface 98 in a brake operation state, and responds to the backward movement of the input piston 25 relative to the valve piston 34 when the emergency brake is released. Then, the connecting pieces 91 are moved radially outward of the valve cylinder 20B so as to contact the inclined surfaces 98 and disengage the engaging portions 97 from the locking portions 68.

  The connecting pieces 91 are urged in the radial direction inward of the valve cylinder 20B and in the forward or backward direction in the axial direction by receiving the elastic force from the elastic members 92. Thus, a pressure receiving surface 99 is provided for contacting the elastic member 92. Thus, in the fourth embodiment, the elastic members 92 are in contact with the connecting portions 91c of the connecting pieces 91, and the connecting portions 91c are separated from the axis of the valve cylinder 20B toward the front. The tapered pressure receiving surfaces 99 inclined so as to be separated from each other are provided, and the elastic members 92 abut against the pressure receiving surfaces 99, so that the connecting pieces 91 are arranged radially inward and axially forward of the valve cylinder 20B. Will be energized.

  In this way, the resilient force of the elastic members 92 urges the connecting pieces 91 inward in the radial direction of the valve cylinder 20B and urges backward in the axial direction of the valve cylinder 20B. Therefore, it is possible to prevent the connecting pieces 91 from rattling in the axial direction of the valve cylinder 20B, to ensure a smooth operation of the connecting pieces 91, and to stabilize the brake assist characteristics.

  The valve cylinder 20B is provided with sliding protrusions 101, 101, 102, which contact the connecting pieces 91 to guide the sliding operation of the connecting pieces 91. Thus, the pair of sliding protrusions 101, 101 are projected from the inner surface of the radial communication hole 54 so as to be in sliding contact with the rear surface of the connecting piece 91 in the radial communication hole 54. These are arranged so as to extend in parallel along the radial direction of the valve cylinder 20B. Further, the sliding protrusion 102 can be brought into sliding contact with the front surface of the connecting piece 91 in the radial communication hole 54 with the protrusion 93 protruding rearward from the front end face of the radial communication hole 54. Projecting.

  In addition, the hardness of the sliding protrusions 101, 101,..., 102,... Is set lower than the hardness of the connecting piece 91 that makes the sliding protrusions 101, 101,. In the third embodiment, the valve cylinder 20B is a synthetic resin such as polybutylene terephthalate resin (PBT), while the connecting piece 91 is made of a synthetic resin having a hardness higher than that of the valve cylinder 20B, such as polyphthalate. Formed with amide resin (PPA).

  According to the third embodiment as described above, not only the same effects as those of the first and second embodiments can be obtained, but also an arc shape is formed in common to the pair of connecting pieces 91. Since the single elastic member 92 is mounted in the mounting groove 95 provided on the outer periphery of the valve cylinder 20B while being in contact with the connecting pieces 91, the number of parts can be reduced.

  In addition, since the valve cylinder 20B is provided with the rotation stopper 100 that abuts both ends of the elastic member 92 in the circumferential direction and restricts the movement of the elastic member 92 in the circumferential direction, the elastic member 92 can be easily positioned in the circumferential direction and assembled. Will improve.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. Is possible.

It is a longitudinal cross-sectional view of the negative pressure booster of 1st Embodiment. FIG. 2 is an enlarged view of a portion indicated by an arrow 2 in FIG. 1 when the negative pressure booster is in an inoperative state, and is a cross-sectional view taken along line 2-2 in FIG. 3. FIG. 3 is a sectional view taken along line 3-3 in FIG. 2. FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. FIG. 5 is a sectional view taken along line 5-5 of FIG. FIG. 6 is a sectional view taken along line 6-6 in FIG. It is a perspective view of an elastic member and a connection piece. It is sectional drawing corresponding to FIG. 2 in a normal brake state. It is a diagram which shows the output characteristic of a negative pressure booster. It is sectional drawing corresponding to FIG. 2 in an emergency brake state. It is sectional drawing corresponding to FIG. 2 in an emergency brake cancellation | release state. It is a perspective view of the connection piece of 2nd Embodiment. FIG. 9 is a cross-sectional view corresponding to FIG. 2 when a negative pressure booster is in a non-operating state, showing a third embodiment. FIG. 14 is a cross-sectional view taken along line 14-14 of FIG. FIG. 15 is a cross-sectional view taken along line 15-15 in FIG. 13. It is a perspective view which shows the relative arrangement | positioning of an elastic member and a connection piece.

Explanation of symbols

11 ... Booster shell 15 ... Booster piston 17 ... Negative pressure chamber 18 ... Working chambers 20A, 20B ... Valve 25 ... Input piston 26 ... Input rod 27 ... Control Valve 34 ... Valve piston 65A, 65B, 91 ... Connection piece 65d, 65e, 85, 86, 101, 102 ... Sliding projection 66, 92 ... Elastic member V ... Negative pressure source

Claims (3)

  The booster shell (11) accommodates a booster piston (15) that divides the booster shell (11) into a front negative pressure chamber (17) and a rear working chamber (18) connected to the negative pressure source (V). A valve cylinder (20A, 20B) slidably supported on the rear wall of the shell (11) is connected to the booster piston (15), and is linked to and connected to an input rod (26) that can move back and forth. The piston (25) and the input piston (25) can be slid forward from a predetermined retracted position, and are fitted to the input piston (25) and elastically biased toward the retracted position. A valve piston (34) and a control valve (27) for switching the working chamber (18) between the negative pressure chamber (17) and the atmosphere in response to the longitudinal movement of the input rod (26) include the valve cylinder ( 20A, 20B) and the input During emergency braking in which the ston (25) and the valve piston (34) advance ahead of the valve cylinder (20A, 20B) by a predetermined stroke or more, they engage with the valve piston (34) to engage the valve cylinder (20A, 20B). ), The connecting piece (65A, 65B, 91) that maintains the axial relative position of the valve piston (34) constant with respect to the valve cylinder (20A, 20B) can move along the radial direction of the valve cylinder ( 20A, 20B) is slidably fitted, and the connecting piece (65A, 65B, 91) is inserted between the valve cylinder (20A, 20B) and the connecting piece (65A, 65B, 91). , 20B), a negative pressure booster provided with an elastic member (66, 92) urging inward along the radial direction of the valve cylinder (20A, 20B) and the connecting piece (65A, 65B). 91) is brought into contact with the other of the valve cylinder (20A, 20B) and the connecting piece (65A, 65B, 91) to guide the sliding operation of the connecting piece (65A, 65B, 91). A negative pressure booster provided with sliding protrusions (85, 86; 65d, 65e, 101, 102).   The hardness of the sliding protrusions (85, 86; 65d, 65e, 101, 102) is set lower than the hardness of the other of the valve barrel (20A, 20B) and the connecting piece (65A, 65B, 91). The negative pressure booster according to claim 1.   A plurality of the sliding protrusions (85, 65d, 101) are provided on one of the opposing surfaces of the connecting piece (65A, 65B, 91) and the valve tube (20A, 20B) on the connecting piece (65A, 65B, 101). 91. The negative pressure booster according to claim 1, wherein the negative pressure booster is provided so as to extend in parallel with the sliding direction of 91).

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