JP2011111117A - Electric booster, assembling tool for the electric booster, and assembling method of the electric booster - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric booster device, which is facilitated in assembling operation. <P>SOLUTION: The electric booster 1 includes an annular cup 38A, an annular plate 38B and an O-ring 38C between a booster piston 24 and an input rod 22, and a recessed portion 48 is formed at the distal end of the input rod 22 as a positioning part with the assembling tool 70 which is moved axially within the booster piston 24 so as to be fitted to the annular plate 38B and the O-ring 38C. Therefore, the assembling operation is facilitated. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electric booster employed in a vehicle brake mechanism, an assembly jig for the electric booster, and an assembly method for the electric booster.

  In a conventional electric booster, an input piston whose front end faces from the central through hole of the booster piston is provided in the pressure chamber of the master cylinder, and the seal member seals the pressure chamber between the input piston and the central through hole of the booster piston. Is provided (see Patent Document 1).

JP 2007-191133 A

  However, in the electric booster disclosed in Patent Document 1, when the input piston is inserted into the central through hole of the booster piston, it is necessary to perform carefully so that the seal member is not caught or damaged or dropped due to the tip of the input piston. As a result, assembly work was complicated.

  The present invention has been made in view of such points, and an object thereof is to provide an electric booster that facilitates assembly work, an assembly jig for the electric booster, and an assembly method for the electric booster. And

As means for solving the above problems, the invention of the electric booster according to the present invention comprises: a shaft member that moves forward and backward by operation of a brake pedal; and a cylindrical member that is externally movable on the shaft member; An electric actuator for moving the cylindrical member forward and backward, wherein the shaft member and the cylindrical member serve as pistons of the master cylinder, the front ends thereof face the pressure chambers of the master cylinder, and the shaft from the brake pedal to the shaft. In the electric booster that generates brake hydraulic pressure in the master cylinder by the input thrust applied to the member and the booster thrust applied from the electric actuator to the cylindrical member, the electric booster An annular seal member is provided between the tubular member and the shaft member, and the tubular member is fitted at the tip of the shaft member so that the shaft member is fitted to the seal member. It is characterized in that the positioning portion between the assembly jig for moving the timber in the axial direction is formed.
An invention of an assembly jig for an electric booster according to the present invention is an assembly jig for an electric booster according to claim 1 or 2, wherein the assembly jig is an assembly of the electric booster. A bottomed cylindrical holder that holds a cylindrical member that is externally movable on a shaft member that moves forward and backward by operating the brake pedal, and a bottom wall portion of the holder that hermetically penetrates the holder And a guide rod having a positioning portion corresponding to the positioning portion provided at the tip of the shaft member, and the guide rod engages the positioning portion with the positioning portion of the shaft member. In this state, the shaft member is guided in the axial direction while being fitted to an annular seal member disposed on the inner peripheral surface of the cylindrical member in the holding body, and the seal member is guided to the shaft member and the cylinder. It arrange | positions between the shaped members.
Furthermore, the invention of the electric booster assembling method according to the present invention is the electric booster assembling method according to claim 1 or 2, wherein the electric booster is moved forward and backward by operation of a brake pedal. A bottomed cylindrical holder that holds a cylindrical member that is externally mounted on a shaft member that can be moved relative to the shaft member, and the bottom wall portion of the holder is hermetically penetrated and can be moved back and forth in the axial direction in the holder. An annular seal member is attached to the guide rod extending in the axial direction in the holding body using an assembly jig having a guide rod having a positioning portion corresponding to the positioning portion provided at the tip of the shaft member An attachment step; and the cylindrical member of the electric booster is inserted into the guide rod, the seal member is disposed between the guide rod and the cylindrical member, and the cylindrical member is held. A holding step for holding by the body, and the guide rod; An engaging step for engaging the positioning portion provided at the tip of the shaft member with the positioning portion, moving the guide rod in the axial direction, guiding the shaft member in the axial direction, and connecting the shaft member to the seal member And a fitting step of fitting the sealing member between the shaft member and the tubular member.

  According to the electric booster of the present invention, the assembly jig of the electric booster, and the assembly method of the electric booster, the assembling work can be facilitated.

FIG. 1 is a cross-sectional view of an electric booster according to an embodiment of the present invention. FIG. 2 is a side view showing an assembly jig for a piston assembly employed in the electric booster. 3 (a) and 3 (b) are diagrams showing the method of assembling the piston assembly step by step. 4 (c) and 4 (d) are diagrams showing the assembly method continued from FIG. 3 (b) step by step. 5 (e) and 5 (f) are diagrams showing the assembly method continued from FIG. 4 (d) step by step. FIG. 6G is a view showing an assembling method continued from FIG.

Hereinafter, embodiments for carrying out the present invention will be described with reference to FIGS.
FIG. 1 shows the structure of the electric booster according to the present embodiment. The electric booster 1 has a motor casing 3 having one end fixed to a partition wall W that partitions the engine room R1 and the vehicle compartment R2 and a tandem master cylinder 2 described later connected to the other end (hereinafter abbreviated as a casing as appropriate). It has. For convenience of explanation, the engine room R1 side is hereinafter referred to as the front side, and the vehicle compartment R2 side is referred to as the rear side.

The casing 3 includes a cylindrical casing body 4 and a rear cover 6 that is bolted to the rear end of the casing body 4 and seals the opening of the rear end of the casing body 4 together with the seal member 5. A stepped front wall 7 is integrally provided at the front end of the casing body 4, and the tandem master cylinder 2 is fixed to the front wall 7 using a stud bolt 10. The rear cover 6 is fixed to the partition wall W by using stud bolts 11. In this fixed state, a cylindrical boss portion 12 provided integrally with the rear cover 6 passes through the partition wall W and extends into the vehicle interior R2. Is issued.
The front wall 7 of the casing body 4 has a front wall body 15 formed so as to be substantially orthogonal to the casing body 4, and the front wall body 15 has an inner diameter dimension that decreases in order from the front side to the rear side. The middle, large annular first, second and third step portions 15a, 15b and 15c are provided and stepped as described above. The first, second, and third step portions 15a, 15b, and 15c of the front wall main body 15 have respective inner diameter dimensions that fit a bearing 20 and a stator coil 21a of the stator 21 and a stator main body 21b, which will be described later. It is set to the size to get. In the present embodiment, the second and third step portions 15b and 15c constitute a step portion to which the stator 21 is attached.

  The casing 3 includes a piston assembly 23 shared as a primary piston of the tandem master cylinder 2 and an electric actuator 25 that drives a booster piston 24 as a cylindrical member constituting the piston assembly 23. An ECU 26 (to be described later) for controlling the driving of the electric actuator 25 is integrally provided on the upper portion of the casing 3 (the casing body 4 and the rear cover 6).

  A tandem master cylinder (hereinafter simply referred to as a master cylinder) 2 includes a bottomed cylinder body 30 and a reservoir 31, and a pair of a piston assembly 23 serving as a primary piston is paired on the front side of the cylinder body 30. A secondary piston 32 is slidably disposed. In the cylinder body 30, two pressure chambers 33 </ b> A and 33 </ b> B are defined by the piston assembly 23 and the secondary piston 32, and are enclosed in the pressure chambers 33 </ b> A and 33 </ b> B as the pistons 23 and 32 advance. The brake fluid is pumped from the discharge ports 34 </ b> A and 34 </ b> B provided in the cylinder body 30 to the corresponding wheel cylinder WC.

  The cylinder body 30 is formed with relief ports 35A and 35B communicating the pressure chambers 33A and 33B with the reservoir 31, and the cylinder body 30 has an inner surface on the front side of the relief ports 35A and 35B, respectively. Seal members 36A and 36B are disposed. In each of the pressure chambers 33A and 33B, return springs 37A and 37B are provided for constantly urging the piston assembly 23 as a primary piston and the secondary piston 32 in the backward direction. Further, a sleeve 96 is disposed between the annular wall portion 24a formed on the inner periphery of the booster piston 24 and the spring receiver of the return spring 37A. The pressure chambers 33A and 33B communicate with the reservoir 31 via relief ports 35A and 35B at the retracted ends of the pistons 23 and 32, whereby the necessary brake fluid is supplied from the reservoir 31 to the pressure chambers 33A and 33B. The

The piston assembly 23 includes a booster piston 24 as a cylindrical member and an input piston 22 as a shaft member. The solid input piston 22 is placed in a cylindrical booster piston 24. It is arranged to be relatively movable. The booster piston 24 is slidably fitted into a cylindrical guide 40 fitted to the front wall 7 of the casing body 4, and its front end extends into the pressure chamber 33 </ b> A of the master cylinder 2. .
On the other hand, the input piston 22 is slidably fitted into a through hole inside the annular wall portion 24 a formed on the inner periphery of the booster piston 24, and its front end portion extends into the pressure chamber 33 </ b> A of the master cylinder 2. Has been issued.
The booster piston 24 and the cylinder body 30 of the master cylinder 2 are sealed by a seal member 36A, and the seal member, that is, an annular member, is formed between the annular wall portion 24a of the booster piston 24 and the input piston 22. Sealing is performed by a cup (plunger) 38A, an annular plate 38B, and an O-ring 38C, thereby preventing leakage of brake fluid from the pressure chamber 33A to the outside of the master cylinder 2.

  On the other hand, at the rear end portion of the input piston 22, a tip end portion of an input rod 41 interlocking with a brake pedal (not shown) is slidably connected to the spherical concave portion, and the input piston 22 is connected to the brake pedal. The booster piston 24 is moved back and forth by an operation (pedal operation). Further, a triangular pyramid-shaped concave portion 48 corresponding to a convex portion 72 provided on a guide rod 73 of an assembly jig 70 described later is formed on the front end surface of the input piston 22 as a positioning portion. In the middle of the input rod 41, an enlarged diameter portion 41a is integrally formed, and the input rod 41 is an inward projection in which the enlarged diameter portion 41a is integrally formed at the rear end of the cylindrical guide portion 12 of the rear cover 6. The rearward movement (vehicle compartment R2 side) is restricted by contacting with 42. That is, the position where the input piston 22 abuts the enlarged diameter portion 24 a of the input rod 41 on the inward protrusion 25 of the rear cover 6 is the retracted end.

  The electric actuator 25 includes an electric motor 45 and a ball screw mechanism 36 that converts the rotation of the electric motor 45 into a linear motion and transmits it to the booster piston 24. The electric motor 45 includes a stator 21 having a plurality of coils 21 a and a stator main body 21 b around which the plurality of coils 21 a are wound, and a hollow rotor 50 that is rotated by energization of the stator 21. It has become. A plurality of coils 21a wound around the stator body 21b (generally referred to as the stator coil 21a as appropriate for convenience) are formed in an annular shape as a whole.

  The electric motor 45 is fixed to the casing body 4 with bolts 51 in a state where the stator 21 is fitted to the second and third step portions 15 b and 15 c, and the rotor 50 is interposed via the bearings 20 and 52. The casing body 4 and the rear cover 6 are rotatably supported. In addition, the bearing 20 is arrange | positioned in the state fitted to the 1st step part 15a and the casing main body 4. FIG. The bearing 52 is provided to be fitted to the step portion of the rear cover 6.

  The ball screw mechanism 36 includes a nut member 54 that is non-rotatably fitted and fixed to the rotor 50 of the electric motor 45 using a key 53, and a hollow screw shaft 56 that is engaged with the nut member 54 via a ball 55. It is made up of. A slit 57 extending in the axial direction is formed at the rear end of the screw shaft 56, and the inward projection 42 of the rear cover 6 is inserted into the slit 57. In other words, the screw shaft 56 is disposed in the casing 3 so as not to rotate. As a result, when the nut member 54 rotates together with the rotor 50, the screw shaft 56 moves directly.

  On the other hand, an annular protrusion 60 is provided on the inner surface of the screw shaft 56, and a flange member 61 screwed to the rear end portion of the booster piston 24 abuts on the annular protrusion 60. A return spring 62 is interposed between the flange member 61 and the cylindrical guide 40 fitted to the casing body 4, and the booster piston 24 always attaches the flange member 61 to the screw shaft 56 by the return spring 62. The state of being in contact with the annular protrusion 60 on the side is maintained. Therefore, when the screw shaft 56 moves forward according to the rotation of the nut member 54, the booster piston 24 is also moved forward by being pushed by the screw shaft 56. In the present embodiment, the screw shaft 56 is positioned at the retracted end where the start end of the slit 57 abuts against the inner protrusion 42 on the rear cover 6 side when the brake is not operated. At the time of non-operation, it is positioned at the retracted end to be brought into contact with the annular protrusion 60 of the screw shaft 56 at the retracted end. A presser spring 63 is interposed between the screw shaft 56 and the cylindrical guide 40 to urge the screw shaft 56 rearward and restrict the screw shaft 56 from advancing inadvertently.

  In addition, a pair of balance springs 65 and 65 are disposed between the booster piston 24 and the input piston 22 constituting the piston assembly 23. The pair of balance springs 65 serves to hold the booster piston 24 and the input piston 22 in a neutral position relative to each other when the brake is not operated.

  In the present embodiment, a potentiometer (not shown) that detects the absolute displacement of the input piston 22 with respect to the vehicle body through the movement of the input rod 41 (or brake pedal) is disposed in the fixed portion in the passenger compartment R2. In the casing 3, a resolver (rotation detecting means) 66 that detects the absolute displacement of the booster piston 24 relative to the vehicle body from the rotational displacement of the electric motor 45 is disposed. The resolver 66 includes a resolver stator 66 a that is bolted to the rear cover 6 and a resolver rotor 66 b that is disposed on the outer peripheral surface of the rotor 50 of the electric motor 45.

Next, the operation of the electric booster 1 configured as described above will be described.
When the input rod 41, that is, the input piston 22, moves forward in response to the depression of the brake pedal, the movement is detected by the potentiometer. Then, in response to the signal from the potentiometer, an activation command is output from the ECU 26 to the electric motor 45, whereby the rotor 50 of the electric motor 45 rotates, and the rotation is converted into a linear motion by the ball screw mechanism 36, thereby booster booster. It is transmitted to the piston 24. That is, the input piston 22 and the booster piston 24 are integrally advanced (promoted), and depending on the input thrust applied from the brake pedal to the input piston 22 and the booster thrust applied from the electric motor 45 to the booster piston 24. The brake fluid pressure is generated in the pressure chambers 33A and 33B in the master cylinder 2.

Next, an assembly jig 70 according to the present embodiment employed when assembling the electric booster 1 according to the present embodiment described above will be described with reference to FIGS.
The assembly jig 70 according to the present embodiment assembles a piston assembly 23 in which the booster piston 24 includes the input piston 22 so as to be movable relative to the booster piston 24 in the electric booster 1 shown in FIG. Used when.

As shown in FIGS. 2 and 3, the assembly jig 70 includes a bottomed cylindrical lower holding body 71 that holds the booster piston 24 of the piston assembly 23, and a bottom wall portion of the lower holding body 71. 74, the guide rod 73 having a triangular pyramid-shaped convex portion 72 corresponding to the concave portion 48 provided at the tip of the input piston 22 at the tip, and extending in the lower holder 71 in an airtight manner. The piston assembly 23 is held between the lower cylinder 71 and an air cylinder 76 that allows the distal end of the cylinder rod 75 to come into contact with the base end portion of the guide rod 73 to move the guide rod 73 in the axial direction. An upper holding body 77 (see FIG. 4) is provided.
As shown in FIG. 2, an arm 79 extending in the vertical direction from one end of the rotating shaft 78 is fixed to the lower holding body 71, and a handle 80 is provided at the other end of the rotating shaft 78. The rotary shaft 78 is rotatably supported on the upper end of the support column 81, and the support column 81 extends upward from the gantry 82. An air cylinder 76 is provided below the gantry 82. Then, when the operator rotates the handle 80 in a direction orthogonal to the paper surface, the lower holding body 71 is rotated in the same direction around the rotation shaft 78.

As shown in FIG. 3, the lower holding body 71 includes a cylindrical portion 85 and a bottom wall portion 74 that hermetically closes the lower end opening of the cylindrical portion 85. A plurality of fixing bolts are used for fixing the cylindrical portion 85 and the bottom wall portion 74.
On the upper inner peripheral surface of the cylindrical portion 85, O-rings 86 are respectively incorporated in annular recesses formed at two positions with a space in the vertical direction. A radial through hole 87A for pressurization and measurement is formed between the O-rings 86. As shown in FIG. 3B, the radial through hole 87A is opposed to the radial through hole 89 provided in the annular wall portion 24a when the booster piston 24 is set on the lower holding body 71. It is formed in the position to do. A radial through hole 87B for pressurization and measurement is formed at a distance from the radial through hole 87A downward. An O-ring 86 is incorporated in an annular recess formed outward from the stepped portion 88 on the upper surface of the tubular portion 85.
The bottom wall portion 74 includes a disc portion 90 and a rod-shaped guide portion 91 that integrally extends upward from the approximate center of the disc portion 90. An annular recess is formed around the rod-shaped guide portion 91 on the upper surface of the disc portion 90, and an O-ring 86 is incorporated in the annular recess. In the rod-shaped guide portion 91, a through hole 92 through which the guide rod 73 is inserted extends in the vertical direction. The rod-shaped guide portion 91 is formed at a height such that the tip thereof is substantially at the same position as the lower radial through hole 87B provided in the cylindrical portion 85 of the lower holding body 71. The outer diameter of the rod-shaped guide portion 91 substantially matches the outer diameter of the sleeve 96 that is a component of the electric booster 1. Further, two annular recesses are formed on the lower inner peripheral surface of the through hole 92 of the rod-shaped guide portion 91 with a space in the vertical direction, and an O-ring 86 is incorporated in each annular recess.

When the guide rod 73 is inserted into the rod-shaped guide portion 91 of the bottom wall portion 74, the upper end of the guide rod 73 protrudes beyond the upper end of the lower holding body 71. The outer diameter of the guide rod 73 is substantially the same as the outer diameter of the input piston 22 of the piston assembly 23. A large diameter portion 93 larger than the outer diameter of the guide rod 73 is integrally formed at the lower end of the guide rod 73. Further, a triangular pyramid-shaped convex portion 72 as a positioning portion corresponding to the triangular pyramid-shaped concave portion 48 provided at the distal end of the input piston 22 is formed on the distal end surface of the guide rod 73.
The air cylinder 76 is fixed below the mount 82 so that the axis of the cylinder rod 75 and the axis of the guide rod 73 coincide.

  As shown in FIG. 4, the upper holding body 77 is formed in a columnar shape that substantially matches the outer diameter of the cylindrical portion 85 of the lower holding body 71, and the upper holding body 77 includes the input piston 22 and the booster piston 24. A housing hole 95 for housing the housing extends in the vertical direction. The inner diameter of the accommodation hole 95 is determined in accordance with the outer diameter of each part of the booster piston 24 and each part of the input piston 22, and the inner diameter is gradually reduced as it goes upward. In addition, a radial through hole 87 </ b> C for pressurization and measurement that opens to the accommodation hole 95 is formed in the peripheral wall of the upper holding body 77. The lower end inner diameter of the accommodation hole 95 of the upper holding body 77 substantially matches the outer diameter of the stepped portion 88 provided on the upper surface of the lower holding body 71. The upper holding body 77 is configured to advance and retreat toward the lower holding body 71 by a driving unit (not shown).

Next, an assembly method of the piston assembly 23 of the electric booster 1 using the assembly jig 70 described above will be described with reference to FIGS.
In the initial state, as shown in FIG. 3A, the cylinder rod 75 of the air cylinder 76 extends to the maximum and the guide rod 73 that contacts the tip of the cylinder rod 75 is connected to the bottom wall portion 74 of the lower holding body 71. The rod-shaped guide portion 91 is hermetically inserted and protrudes from the upper end of the lower holding body 71.
First, the sleeve 96 is inserted into the guide rod 73, and the sleeve 96 is positioned above the rod-shaped guide portion 91.
Next, an annular cup 38A, an annular plate 38B, and an O-ring 38C as seal members are inserted into the upper portion of the guide rod 73 in this order. This process corresponds to an attachment step.

  Next, as shown in FIG. 3B, the booster piston 24 is inserted into the lower holding body 71, and the guide rod 73 is inserted into the through hole inside the annular wall portion 24 a provided in the booster piston 24. The O-ring 38C, the annular plate 38B, and the annular cup 38A are arranged in this order on each step on the inner peripheral surface of the annular wall 24a. As a result, the O-ring 38C, the annular plate 38B, and the annular cup 38A are disposed between the guide rod 73 and the booster piston 24. At the same time, the shoulder of the sleeve 96 comes into contact with the lowermost step portion of the annular wall portion 24a of the booster piston 24, and the inner peripheral surface below the annular wall portion 24a of the booster piston 24 is the sleeve 96 and the rod-shaped guide. It abuts on the outer peripheral surface of the portion 91. Subsequently, the balance spring 65 is disposed in the booster piston 24 at a position above the annular wall portion 24a. This process corresponds to a holding step.

Next, as shown in FIG. 3 (b), the input rod 41 having the flange member 61 is swingably supported in the spherical concave portion of the input piston 22, and the input piston 22 and the flange member 61 A partial assembly 100 having a balance spring 65 disposed therebetween is prepared. As shown in FIG. 4C, a convex portion provided with a concave portion 48 at the distal end of the input piston 22 of the partial assembly 100 at the distal end of the guide rod 73. Engage with the portion 72. This process corresponds to an engagement step.
Next, as shown in FIG. 4 (c), the cylinder rod 75 of the air cylinder 76 is inserted into the cylinder and the subassembly 100 is pushed in, so that the flange member 61 is screwed onto the upper inner peripheral surface of the booster piston 24. Match. Then, the front portion of the input piston 22 is inserted into the through hole inside the annular wall portion 24a of the booster piston 24 so that the front portion of the input piston 22 is guided to the guide rod 3, and the upper end of the balance spring 65 in the booster piston 24 is connected to the input piston. 22 abuts against the spring receiving portion. In this way, the input piston 22 is guided in the axial direction while being positioned in the booster piston 24 without being displaced left and right by the guide rod 73, and finally the O-ring 38C, the annular plate 38B, and the annular cup 38A are input. It is arranged between the piston 22 and the booster piston 24. At this time, the cylinder rod 75 of the air cylinder 76 and the guide rod 73 are separated from each other, but the position of the guide rod 73 is maintained without dropping due to frictional resistance with the O-ring 86. This process is a fitting step.

  Next, as shown in FIG. 4D, the upper holding body 77 is moved downward so that the lower end annular surface 102 is brought into contact with the upper surface outward from the stepped portion 88 of the lower holding body 71. Thereby, a sealed space is formed from the accommodation hole 95 of the upper holding body 77 to the inside of the lower holding body 71. The sealed space 105 is divided into upper and lower sealed spaces 106 and 107 with an O-ring 38C, an annular plate 38B, and an annular cup 38A as seal members disposed between the input piston 22 and the booster piston 24 as boundaries. The

Next, in the state of FIG. 4D, an airtight test is performed to inspect whether or not the O-ring 38C, the annular plate 38B, and the annular cup 38A are assembled in a normal state. This process corresponds to a test step.
Specifically, the O-ring 38C, the annular plate 38B, and the annular cup are pressurized by applying pressure from the radial through hole 87C provided in the upper holding body 77 and measuring the pressure, specifically, the pressure in the upper sealed space 106. Check for the presence of 38A. As a result, when it is confirmed that the pressure in the upper sealed space 106 is maintained, it is determined that the O-ring 38C, the annular plate 38B, and the annular cup 38A are incorporated as normal. On the other hand, when the pressure in the upper sealed space 106 decreases, it is determined that any of the O-ring 38C, the annular plate 38B, and the annular cup 38A is missing.

  Further, it is inspected whether or not the annular cup 38A is assembled in a normal posture. This inspection includes the following two inspection methods. First, as a first inspection method, pressure is applied from the lower radial through hole 87B provided in the lower holding body 71, and the pressure, specifically, the pressure in the lower sealed space 107 is held. Is measured. In this case, if the pressure in the lower sealed space 107 is maintained, it is determined that the annular cup 38B is incorporated in a normal posture. If the pressure is not maintained, the annular cup 38B is reversed. It is determined that it is incorporated. Further, as a second inspection method, if the pressure is applied from the upper radial through hole 87A provided in the lower holding body 71 and the pressure falls without being held, it is determined that the annular cup 38B is incorporated in a normal posture. On the other hand, if the pressure is maintained, it is determined that the annular cup 38B is incorporated in the reverse direction.

Next, as shown in FIG. 5E, the upper holding body 77 is moved upward to expose a part of the piston assembly 23 to the outside. Subsequently, as shown in FIG. 5 (f), by rotating the handle 80 (see FIG. 2), the piston assembly 23 held by the lower holding body 71 is rotated 180 ° in a direction perpendicular to the paper surface. The exposed piston assembly 23 faces downward. Thereby, the fall of the sleeve 96 arrange | positioned in the booster piston 24 can be prevented.
Finally, as shown in FIG. 6G, the operator pushes the guide rod 73 in a state protruding from the upper end of the lower holding body 71 into the lower holding body 71, thereby lowering the piston assembly 23. Remove from the side holder 71.

If the assembly method according to the present embodiment as described above is employed by employing the assembly jig 70 according to the present embodiment, the input piston 22 is positioned in the booster piston 24 when the piston assembly 23 is assembled. Therefore, the input piston 22 is smoothly fitted to the O-ring 38C, the annular plate 38B, and the annular cup 38A, and the O-ring 38C, the annular plate 38B, and the annular cup 38A are connected to the input piston 22. It can be arranged between the annular wall portion 24a of the booster piston 24 and can prevent damage and dropout of the O-ring 38C and the like when the input piston 22 is inserted, which has been conventionally generated, and facilitates assembly work. can do.
Further, a triangular pyramid-shaped concave portion 48 corresponding to the triangular pyramid-shaped convex portion 72 provided at the distal end of the guide rod 73 of the assembly jig 70 is formed at the distal end of the input piston 22 of the electric booster 1. Therefore, the input piston 22 can be easily positioned on the guide rod 73.

  In the present embodiment, a concave portion 48 corresponding to the convex portion 72 provided at the tip of the guide rod 73 of the assembly jig 70 is formed at the tip of the input piston 22 of the electric booster 1. A convex portion may be formed at the tip of the input piston 22 and a concave portion may be formed at the tip of the guide rod 73 of the assembly jig 70 so as to correspond to this.

DESCRIPTION OF SYMBOLS 1 Electric booster, 2 Tandem master cylinder (master cylinder), 22 Input piston (shaft member), 23 Piston assembly, 24 Booster piston (cylindrical member), 25 Electric actuator, 36 Ball screw mechanism, 33A, 33B Pressure Chamber, 38A annular cup, 38B annular plate, 38CO ring, 41 input rod, 45 electric motor, 48 recess (positioning part), 70 assembly jig, 71 lower holding body (holding body), 72 convex part (positioning part) ), 73 guide rod, 74 bottom wall, 77 upper holding body, 105 sealed space, 106 upper sealed space, 107 lower sealed space

Claims (5)

A shaft member that moves forward and backward by operation of the brake pedal;
A cylindrical member externally mounted on the shaft member so as to be relatively movable;
An electric actuator for moving the tubular member forward and backward,
The shaft member and the cylindrical member are used as pistons of the master cylinder, the front end portions thereof face the pressure chambers of the master cylinder, the input thrust applied from the brake pedal to the shaft member, and the electric actuator In the electric booster that generates the brake fluid pressure in the master cylinder by the booster thrust applied to the tubular member,
The electric booster has an annular seal member between the tubular member and the shaft member,
A positioning portion between the shaft member and an assembly jig for moving the inside of the cylindrical member in the axial direction so as to fit the shaft member to the seal member is formed at the tip of the shaft member. Electric booster.   The electric booster according to claim 1, wherein the positioning portion is formed in a concave shape or a convex shape. An assembly tool for an electric booster according to claim 1 or 2,
The assembly jig includes a bottomed cylindrical holder that holds a cylindrical member that is externally movable on a shaft member that moves forward and backward by operating a brake pedal of the electric booster;
A guide rod having a positioning portion corresponding to the positioning portion provided at the tip of the shaft member, hermetically penetrating the bottom wall portion of the holding body and capable of moving forward and backward in the axial direction within the holding body,
The guide rod is engaged with the annular seal member disposed on the inner peripheral surface of the cylindrical member in the holding body with the positioning portion engaged with the positioning portion of the shaft member. An assembly jig for an electric booster, wherein the sealing member is arranged between the shaft member and the cylindrical member by being guided in an axial direction. An assembly method of the electric booster according to claim 1 or 2,
A bottomed cylindrical holding body that holds a cylindrical member that is externally movable on a shaft member that moves forward and backward by operation of a brake pedal of the electric booster, and a bottom wall portion of the holding body is hermetically sealed Using an assembly jig that includes a guide rod having a positioning portion corresponding to the positioning portion provided at the tip of the shaft member.
An attaching step of attaching an annular seal member to the guide rod extending in the axial direction in the holding body;
The cylindrical member of the electric booster is inserted into the guide rod, the seal member is disposed between the guide rod and the cylindrical member, and the cylindrical member is held by the holding body. Holding step;
An engagement step for engaging a positioning portion provided at a tip of the shaft member with a positioning portion of the guide rod;
The guide rod is moved in the axial direction, the shaft member is guided in the axial direction, the shaft member is fitted into the seal member, and the seal member is disposed between the shaft member and the tubular member. A mating step;
An assembly method for an electric booster, comprising:   After the fitting step, the holding body is hermetically closed in a state where the shaft member, the cylindrical member, and the seal member are accommodated, and a test step for performing an airtight test in a sealed space provided in the holding body is provided. The method of assembling the electric booster according to claim 4.

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