JP2018199448A - Electric booster - Google Patents

Abstract

To provide an electric booster which can prevent co-rotation of an output member without preventing thrust of a thrust transmission member.SOLUTION: Flat surfaces 140, 141 defining a width of two surfaces of a two-chamfer shaft part 139 of an output piston 62 are slidably contacted with contact flat surfaces 142, 143 formed in an opening 138 of a thrust transmission part 82 of a power piston 81, thereby preventing co-rotation of an output piston 62. The output piston 62 is thus prevented from co-rotation without preventing thrust of the power piston 81.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an electric booster that uses a thrust generated by an electric actuator as a boost source.

  Some electric boosters transmit a linear motion thrust of a power piston (thrust transmission member) to a piston of a master cylinder via an output piston (output member) connected to the power piston. In such an electric booster, it is conceivable to suppress a rotational displacement (relative movement around the input rod axis) of the stroke sensor magnet with respect to the Hall IC by preventing the output piston from rotating. For example, Patent Document 1 discloses a structure that prevents the rotation of a hollow screw shaft as a booster member. However, in an electric booster that includes a power piston, the propulsion of the power piston is not hindered. The output piston is required to be prevented from rotating.

JP 2014-69678 A

  It is an object of the present invention to provide an electric booster that can prevent the output member from rotating without obstructing the propulsion of the thrust transmission member.

  In order to solve the above-described problems, an electric booster according to the present invention includes an input member that moves in accordance with an operation of a brake pedal, an electric motor that operates in accordance with a displacement of the input member, and a linear motion of the rotational force of the electric motor. A rotation / linear motion conversion mechanism for converting the thrust into a member; a thrust transmission member connected to the linear motion member to which the linear motion thrust is transmitted; and a thrust transmission member connected to the thrust transmission member. An output member that receives the linear thrust transmitted to the piston of the master cylinder, and a detected member that detects the displacement of the input member. The output member is configured not to rotate with respect to the thrust transmission member, and the thrust transmission member is separated from the linear motion member at the at least one contact portion. When receiving direct acting thrust Wherein to allow the inclination of the thrust transmission member, characterized in that it is supported by the thrust transmission member.

  According to the present invention, the output member can be prevented from rotating without impeding the propulsion of the thrust transmission member.

It is sectional drawing of the master cylinder connected with the electric booster of this embodiment, Comprising: It is a figure which shows the AA cross section in FIG. It is sectional drawing of the master cylinder connected with the electric booster of this embodiment, Comprising: It is a figure which shows the BB cross section in FIG. It is a front side view of the master cylinder connected with the electric booster of this embodiment. It is a disassembled perspective part of the principal part of the electric booster of this embodiment. It is an enlarged view of the principal part in FIG. It is an enlarged view of the principal part in FIG. It is a front side view which shows the contact structure of a power piston and a nut member. It is a front view which shows the contact structure of a power piston and a nut member.

An embodiment of the present invention will be described with reference to the accompanying drawings.
1 and 2 are cross-sectional views of the electric booster 1 according to the present embodiment, taken along an axial plane. In the following, for convenience, the left direction and the right direction in FIGS. 1 and 2 are defined as the front direction (front side) and the rear direction (rear side) in the electric booster 1, and the upper direction and the lower direction in FIG. It demonstrates as the upward direction and the downward direction in the booster 1. FIG.

  Referring to FIGS. 1 and 2, the electric booster 1 is connected to a rear end portion of a tandem master cylinder 2. The master cylinder 2 has a cylinder body 3 in which a bottomed cylinder bore 4 is formed. A front end portion formed in a cup shape of a primary piston 5 (piston) driven by power generated by the electric booster 1 is inserted into the opening side (rear side) of the cylinder bore 4. The rear end portion of the primary piston 5 extends from the opening of the master cylinder 2 into the housing 41 of the electric booster 1. On the bottom side (front side) of the cylinder bore 4, a cup-shaped secondary piston 6 having an open front side is fitted.

  The cylinder body 3 includes a primary chamber 7 defined by the cylinder bore 4, the primary piston 5 and the secondary piston 6, and a secondary chamber 8 formed between the bottom of the cylinder bore 4 and the secondary piston 6. The primary chamber 7 and the secondary chamber 8 supply a working fluid pressure (referred to as “hydraulic pressure” for convenience) to the wheel cylinder of each wheel of the vehicle via a port (not shown) provided in the cylinder body 3. Connected to two hydraulic circuits. The cylinder body 3 has a port 10 for connecting the primary chamber 7 to the reservoir 9 and a port 11 for connecting the secondary chamber 8 to the reservoir 9.

  On the inner peripheral surface of the cylinder bore 4, annular seal grooves 12 and 13 are formed that are provided at a predetermined interval in the front-rear direction. The seal grooves 12 and 13 are provided with seal rings 14 and 15 for sealing between the cylinder bore 4 and the primary piston 5. On the inner peripheral surface of the cylinder bore 4, annular seal grooves 16 and 17 are formed that are provided at a predetermined interval in the front-rear direction. The seal grooves 16 and 17 are provided with seal rings 18 and 19 for sealing between the cylinder bore 4 and the secondary piston 6. In the non-braking state (see FIGS. 1 and 2), the port 10 opens between the seal rings 14 and 15, and the port 11 opens between the seal rings 18 and 19.

  Here, when the primary piston 5 is located at the non-braking position (see FIGS. 1 and 2), the primary chamber 7 passes through the port 20 provided on the front side wall of the primary piston 5 and the port 10 of the cylinder body 3. Then, it is communicated with the reservoir 9. When the primary piston 5 moves forward from the non-braking position and the port 20 reaches the seal ring 15, the communication between the primary chamber 7 and the port 10 and the communication between the primary chamber 7 and the reservoir 9 are blocked. Thereby, the hydraulic pressure in the primary chamber 7 increases. The amount of movement of the primary piston 5 from the non-braking position of the primary piston 5 to the disconnection of the communication between the primary chamber 7 and the port 10 (reservoir 9) is a so-called invalid stroke.

  When the secondary piston 6 is located at the non-braking position (see FIGS. 1 and 2), the secondary chamber 8 is a reservoir via the port 21 provided on the front side wall of the secondary piston 6 and the port 11 of the cylinder body 3. 9 is communicated. When the secondary piston 6 moves forward from the non-braking position and the port 21 reaches the seal ring 19, the communication between the secondary chamber 8 and the port 11 and the communication between the secondary chamber 8 and the reservoir 9 are blocked. Thereby, the hydraulic pressure of the secondary chamber 8 rises.

  A primary spring assembly 22 is provided between the primary piston 5 and the secondary piston 6 to determine the distance (interval) between the pistons 5 and 6 in the non-braking state (see FIGS. 1 and 2). The primary spring assembly 22 includes a compression coil spring 23 as a return spring, a locking member 24 provided in a recess at the rear end of the secondary piston 6, a locking member 25 provided in a recess on the front side of the primary piston 5, and one end. Is fixed to the locking member 24 and has a shaft member 26 whose movement in the front-rear direction relative to the locking member 25 at the other end is restricted. The compression coil spring 23 is interposed between the locking members 24 and 25, and the primary spring assembly 22 can be compressed against the spring force of the compression coil spring 23.

  A secondary spring assembly 27 is provided between the secondary piston 6 and the cylinder body 3 to determine the distance (interval) between the secondary piston 6 and the bottom of the cylinder bore 4 in the non-braking state (see FIGS. 1 and 2). It is done. The secondary spring assembly 27 includes a compression coil spring 28 as a return spring, a locking member 29 provided at the bottom of the cylinder bore 4, a locking member 30 provided in a recess on the front side of the secondary piston 6, and one end of the locking member. And a shaft member 31 that is fixed to 30 and is restricted from moving in the front-rear direction with respect to the locking member 29 at the other end. The compression coil spring 28 is interposed between the locking members 29 and 30, and the secondary spring assembly 27 can be compressed against the spring force of the compression coil spring 28.

  The electric booster 1 has a housing 41 that houses a mechanism portion of an electric actuator 61 described later. The housing 41 is divided into a front housing 42 and a rear housing 43. A hole 44 coaxial with the cylinder bore 4 of the master cylinder 2 is provided in the center of the front housing 42, and a front end portion of a cylindrical portion 46 of a base member 45 described later is fitted into the hole 44.

  The rear end portion 3A of the cylinder body 3 of the master cylinder 2 is fitted (press-fitted) to the inner side surface of the front end portion of the cylindrical portion 46 of the base member 45. In other words, the front housing 42 is connected to the cylinder body 3 of the master cylinder 2 via the cylindrical portion 46 of the base member 45. The cylinder body 3 of the master cylinder 2 is fixed to the front housing 42 by using two stud bolts 47 and nuts 48 (see FIG. 3) erected on the front housing 42. Further, a seal member 49 seals between the front housing 42 and the cylindrical portion 46 of the base member 45.

  A cylindrical portion 50 coaxial with the cylinder bore 4 of the master cylinder 2 is formed at the center of the rear housing 43. A substantially cylindrical (tubular) output piston 62 (output member) is slidably fitted into the cylinder 51 inside the cylindrical portion 50. An input piston 64 (input member) coaxial with the output piston 62 is inserted into the output piston 62. A spherical front end portion of the input rod 33 is fitted to the rear end portion of the input piston 64, and the rear end portion of the input rod 33 is connected to the brake pedal 39 via the clevis 34.

  The output piston 62 has a shaft hole 63 in which a small diameter portion 63A, a medium diameter portion 63B, and a large diameter portion 63C are formed in order from the master cylinder 2 side (front side). The spring receiving member 36 is attached to the opening of the shaft hole 63 on the rear end face of the output piston 62, that is, the opening of the large diameter portion 63C. The input rod 33 is urged backward with respect to the output piston 62 by a compression coil spring 35 interposed between a spring receiving portion 37 formed on the input rod 33 and a spring receiving member 36. A flange 67 (rear end portion) of the input piston 64 is slidably fitted to the large diameter portion 63C of the output piston 62, and a plunger portion 66 of the input piston 64 is fitted to the medium diameter portion 63B of the output piston 62. It is inserted. The piston portion 65 of the input piston 64 is slidably fitted to the small diameter portion 63A of the output piston 62, that is, the front end portion of the shaft hole 63.

  Referring to FIGS. 1, 2, and 4, the plunger portion 66 of the input piston 64 is formed with an annular groove 131 in which a clip-shaped stopper 68 is mounted. The stopper 68 is inserted into a stopper groove 69 that passes through the output piston 62 in the vertical direction. As a result, the input piston 64 is allowed to move in the front-rear direction relative to the output piston 62 by the clearance in the front-rear direction between the stopper 68 and the stopper groove 69. Further, the input piston 64 is restricted from moving rearward with respect to the rear housing 43 by the stopper 68 mounted in the annular groove 131 coming into contact with the opening peripheral edge 50A on the front side of the cylindrical portion 50 of the rear housing 43. Is done.

  The displacement of the input rod 33, and hence the displacement of the input piston 64, is detected by a stroke sensor. The stroke sensor includes a sensor magnet 132 (detected member) fixed to the input piston 64 via a pin 134 and a Hall IC (not shown) attached to the rear housing 43. 2 and 4, one end of the pin 134 is press-fitted into the hole 135 on the sensor magnet 132 side, and the other end is press-fitted into the hole 136 on the input piston 64 side. A flat surface 141 of the output piston 62, which will be described later, is provided with a step having a sliding surface 133 on which the bottom surface of the sensor magnet 132 is slidably contacted. A groove 137 that extends in the front-rear direction and through which the pin 134 is inserted is formed in the sliding surface 133 (of the output piston 62). Accordingly, the sensor magnet 132 is disposed so as to face the Hall IC via the side wall of the cylindrical portion 50 of the rear housing 43.

  The electric booster 1 has an output rod 70 that presses (promotes) the primary piston 5 of the master cylinder 2. The output rod 70 is configured by a shaft portion 71 whose front end is in contact with the bowl-shaped bottom portion 32 of the recess on the rear side of the primary piston 5, and a pressure receiving portion 72 connected to the rear end portion of the shaft portion 71. The The pressure receiving portion 72 includes a bottomed cylindrical base portion 73 having an open rear side, and a support column 74 that extends from the center of the base portion 73 in the forward direction (master cylinder 2 side) and supports the shaft portion 71. Inside the base portion 73, a front end portion 62A of the output piston 62 is slidably fitted. The shaft portion 71 of the output rod 70 and the column 74 (pressure receiving portion 72) are connected by a screw 75. In other words, the axial length (full length) of the output rod 70 is adjusted by the screw 75.

  A reaction disk 76 made of an elastic material is provided between the output piston 62 and the output rod 70. The reaction disk 76 is accommodated inside the base 73 of the pressure receiving portion 72 of the output rod 70 and is sealed by the base 73 and the front end 62 </ b> A of the output piston 62. In a non-braking state (see FIGS. 1 and 2), a so-called jump-in clearance is defined between the rear end surface of the reaction disk 76 and the top of the input piston 64 whose front end portion is formed in a conical shape. A gap is provided.

  A spring receiving member 78 is provided so as to cover the base 73 of the pressure receiving portion 72 of the output rod 70, and an annular spring receiving portion 59 formed on the inner peripheral surface of the cylindrical portion 46 of the spring receiving member 78 and the base member 45. A compression coil spring 77 is interposed between the two. As a result, the output piston 62 is urged rearward and comes into contact with a power piston 81 described later. The space on the master cylinder 2 side (inside the cylindrical portion 46) and the space on the rear housing 43 side (inside the housing 41) sandwiching the plate 79 are sealed by an annular seal member 80.

  Referring to FIG. 1, the electric booster 1 includes a power piston 81 (a thrust transmission member) that transmits the thrust generated by the electric actuator 61 to the output piston 62. The power piston 81 is disposed so as to straddle the rotation / linear motion conversion mechanism 60 described later, and is engaged with the rotation / linear motion conversion mechanism 60 and the output piston 62. The power piston 81 includes a thrust transmission portion 82 and levers 83 and 84 extending upward and downward from the thrust transmission portion 82. The power piston 81 is a compression coil spring 85 interposed between a spring receiving portion 86 formed inside the thrust transmission portion 82 of the power piston 81 and an annular plate 79 attached to the rear end surface of the base member 45. Is biased backward. As a result, the power piston 81 has a rear end surface 87 (see FIGS. 5 and 6) of the thrust transmission portion 82 that is open on the front side of the cylindrical portion 50 of the rear housing 43 in the non-braking state (see FIGS. 1 and 2). It abuts on the peripheral portion 50A.

  Referring to FIGS. 5 and 6, a flange receiving portion 89 that receives the flange portion 88 of the output piston 62 is provided inside the thrust transmission portion 82 of the power piston 81. The flange receiving portion 89 is provided between a spring receiving portion 86 of the thrust transmission portion 82 and an opening 138 described later, and is configured by a funnel-shaped inclined surface that is reduced in diameter toward the rear. The rear surface 90 of the flange portion 88 of the output piston 62, that is, the contact surface 90 of the output piston 62 with the flange receiving portion 89 of the power piston 81 is spherical, in other words, depends on the axial plane of the output piston 62. The cross section is constituted by a convex surface 90 having an arc shape. That is, the output piston 62 is brought into contact with the flange receiving portion 89 of the power piston 81 with a spherical contact surface 90.

  Referring to FIGS. 1 and 2, the electric actuator 61 includes an electric motor 91 (electric motor) and a rotation / linear motion conversion mechanism 60 that converts power (rotational force) of the electric motor 91 into thrust of the power piston 81. . The rotation / linear motion conversion mechanism 60 includes two screw shaft members 92 and 93 having rotation axes at positions different from the central axis of the master cylinder 2 and nut members 94 and 95 (direct motions) engaged with the screw shaft members 92 and 93. Moving member). In addition, the screw formed in the screw shaft members 92 and 93 and the nut members 94 and 95 in this embodiment is a trapezoidal screw.

  The screw shaft member 92 is disposed on the upper side with respect to the central axis of the master cylinder 2 and is disposed in parallel with the central axis of the master cylinder 2. The rear end portion 97 of the screw shaft member 92 is supported by the rear housing 43 via a radial bearing 98 and a thrust bearing 99. That is, the rear end portion 97 of the screw shaft member 92 is rotatably supported by the rear housing 43 by a combination of a radial bearing 98 and a thrust bearing 99 coaxial with the radial bearing 98.

  A hub 101 is fixed to the front end portion 100 of the screw shaft member 92. The hub 101 and thus the front end portion 100 of the screw shaft member 92 are rotatably supported by the base member 45 via the radial bearing 102. That is, the screw shaft member 92 is supported by a pair of radial bearings 98 and 102 and one thrust bearing 99 so as to be rotatable about the rotation axis of the screw shaft member 92. A driven pulley 104 is attached to the front end portion 103 of the hub 101 so as not to be relatively rotatable. In other words, the driven pulley 104 is attached to the front end portion 100 of the screw shaft member 92 via the hub 101. The radial bearing 102 is accommodated in a bearing accommodating portion 52 provided in the base member 45. The radial bearing 98 and the thrust bearing 99 are accommodated in a bearing accommodating portion 56 provided in the rear housing 43. The upper end portion 53 and the lower end portion 54 of the base member 45 are fixed to the rear housing 43 by bolts 55.

  Referring to FIGS. 7 and 8, the nut member 94 has the shape of a hexagon nut with a flange having a flange portion 106 formed at the rear end. A front side surface 107 (referred to as a “pressing surface 107” for convenience) of the flange portion 106 is parallel to a plane perpendicular to the axis of the nut member 94 that coincides with the rotational axis of the screw shaft member 92. Eggplant. A pair of surfaces 109 and 110 defining the two-surface width of the hexagonal portion 108 of the nut member 94 are slidably fitted in a groove portion 111 having a constant width formed at the upper end portion of the lever 83 of the power piston 81. The groove 111 extends in the vertical direction and has an upper end opened.

  The rear surface 112 of the upper end portion of the lever 83 of the power piston 81, in other words, the contact surface 112 (contact portion) of the power piston 81 with the pressing surface 107 of the flange portion 106 of the nut member 94 is the power. The section of the piston 81 by the axial plane is formed in a convex arc shape. That is, the power piston 81 is brought into contact with the pressing surface 107 of the nut member 94 at the contact surface 112 formed in a circular arc shape having a convex section in the axial plane. Thus, the lever 83 of the power piston 81 can slide and swing relative to the nut member 94 in a state where the contact surface 112 of the power piston 81 is in contact with the pressing surface 107 of the nut member 94.

  The rotation / linear motion conversion mechanism 60 is configured to be vertically symmetrical. Therefore, in order to simplify the description, the description of the support structure of the screw shaft member 93, the nut member 95, and the connection structure of the nut member 95 and the lever 84 of the power piston 81 will be omitted.

  1 and 2, the electric actuator 61 includes a drive pulley 116 attached to the rotating shaft 115 of the electric motor 91, a driven pulley 104 attached to the screw shaft member 92, and a driven pulley attached to the screw shaft member 93. A pulley 124 and an endless belt 126 wound around a tension pulley 125 are provided. Thereby, the power of the electric motor 91 is transmitted to the screw shaft members 92 and 93 via the endless belt 126. Since each nut member 94, 95 is prevented from rotating relative to each screw shaft member 92, 93, the nut member 94, 95 moves forward or backward along the screw shaft member 92, 93 as the screw shaft member 92, 93 rotates. To do. In other words, the power (rotational force) of the electric motor 91 is converted into the thrust of the nut members 94 and 95.

  The power piston 81 (thrust transmission member) has two contact portions, that is, a contact surface 112 at the upper end portion of the lever 83 and a contact surface 113 at the lower end portion of the lever 84. The movable member is configured to receive a linear thrust. That is, the contact surfaces 112 and 113 of the levers 83 and 84 of the power piston 81 are pressed by the pressing surfaces 107 of the nut members 94 and 95. As a result, the power piston 81 is propelled (advanced) against the spring force of the compression coil spring 85. In other words, the thrust of each nut member 94, 95 is transmitted to the power piston 81. Then, the contact surface 90 of the flange portion 88 of the output piston 62 is pressed by the flange receiving portion 89 of the power piston 81, thereby propelling (advancing) the output piston 62 against the spring force of the compression coil spring 77. Is done. In other words, the thrust of the power piston 81 is transmitted to the output piston 62. Further, the thrust of the output piston 62 is transmitted to the output rod 70 via the reaction disk 76.

Next, a structure that prevents the output piston 62 (output member) from rotating will be described mainly with reference to FIGS. 2, 4, and 6.
The output piston 62 (output member) has a cylindrical two-chamfered shaft portion 139 extending rearward from the rear end of the flange portion 88. A pair of flat surfaces 140 and 141 are formed on the outer periphery of the two-chamfered shaft portion 139 so as to sandwich the shaft hole 63 and the stopper groove 69. The flat surfaces 140 and 141 are arranged in parallel to a straight line connecting the two contact surfaces 112 and 113 (contact portions) with the nut members 94 and 95 of the power piston 81 (thrust transmission member). Although the distance between the axis of the output piston 62 and the plane 140 and the distance between the axis of the output piston 62 and the plane 141 are equal, the distance is not limited to being equal.

  On the other hand, the opening 138 of the thrust transmission portion 82 of the power piston 81 has contact planes 142 and 143 that slidably contact the planes 140 and 141 of the two-chamfered shaft portion 139 of the output piston 62. In other words, the opening 138 is a two-chamfered hole through which the two-chamfered shaft portion 139 of the output piston 62 is slidably inserted. Inner side surfaces 146 and 147 corresponding to the outer side surfaces 144 and 145 which are a part of the outer peripheral surface of the output piston 62 are formed between the contact flat surfaces 142 and 143 facing the opening 138. A notch 150 for inserting the sensor magnet 132 is formed in the contact plane 143 of the opening 138.

  Clearances 148 and 149 (see FIG. 5) are provided between the outer side surfaces 144 and 145 of the output piston 62 and the inner side surfaces 146 and 147 of the power piston 81. The gaps 148 and 149 are formed when the power piston 81 receives linear motion thrust from the nut members 94 and 95 (linear motion members) at the contact surfaces 112 and 113 (two contact sites). Is set so as to allow a difference in movement between the nut members 94 and 95 due to an inclination in the front-rear direction, that is, an assembly error of the electric actuator 61.

  In the electric booster 1 of the first embodiment, when the brake pedal 39 is operated, the input rod 33 moves forward against the urging force of the compression coil spring 35. The operation amount of the brake pedal 39 at this time, that is, the displacement of the input rod 33 is the displacement of the sensor magnet 132 (detected member) attached to the input piston 64 (input member) via the pin 134. It is measured by detecting with a Hall IC (not shown) attached to. The electronic control unit 114 (ECU) controls the electric motor 91 (electric motor) of the electric actuator 61 based on the displacement of the input rod 33 and propels (advances) the nut members 94 and 95 and thus the power piston 81. . The thrust of the power piston 81 is transmitted to the primary piston 5 via the output piston 62 (output member), the reaction disk 76, and the output rod 70.

  When the primary piston 5 moves forward, the electronic control unit 114 controls the electric motor 91 so that the movement amount of the primary piston 5 follows the displacement of the input rod 33, that is, the operation amount of the brake pedal 39. As the primary piston 5 moves forward, the hydraulic pressure in the primary chamber 7 increases, and the hydraulic pressure is transmitted to the secondary chamber 8 via the secondary piston 6. Then, the hydraulic pressure generated in the master cylinder 2 is supplied to the wheel cylinder of each wheel of the vehicle via two hydraulic pressure circuits, thereby generating a braking force by friction braking. The reaction force generated by the hydraulic pressure of the master cylinder 2 generated during braking is transmitted to the input piston 64 (input member) and the output piston 62 via the primary piston 5, the output rod 70, and the reaction disk 76.

  The ratio between the pressure receiving area of the front end surface of the output piston 62 and the pressure receiving area of the piston portion 65 of the input piston 64 becomes a boost ratio (ratio of hydraulic pressure output to the operation input of the brake pedal 39), and is desired. A braking force can be generated. When the operation of the brake pedal 39 is released, the electronic control unit 114 controls the electric motor 91 based on the displacement of the input rod 33, thereby retracting the nut members 94 and 95 and thus the power piston 81. Accordingly, the primary piston 5 and the secondary piston 6 are retracted via the output piston 62, the reaction disk 76, and the output rod 70, the hydraulic pressure of the master cylinder 2 is reduced, and the braking force is released.

  Here, in the electric booster 1 in which the displacement of the input piston 64 (input member) is detected by the stroke sensor, the sensor magnet 132 (detected member) slidable with respect to the output piston 62 (output member) In order to suppress a shift in the rotation direction (around the axis) with respect to the housing 41 (rear housing 43), it is necessary to prevent the output piston 62 from rotating with respect to the housing 41. As in the electric booster 1 of the present embodiment, a structure in which the power piston 81 receives linear thrust from the nut members 94 and 95 (linear motion members) at the contact surfaces 112 and 113 (two contact sites). Then, the output piston 62 is prevented from rotating without impeding the propulsion of the power piston 81, that is, the movement difference between the nut members 94 and 95 due to the assembly error of the electric actuator 61 is allowed. Therefore, it is required to prevent the output piston 62 from rotating so as to allow the power piston 81 to tilt in the front-rear direction.

  On the other hand, in this embodiment, the flat surfaces 140 and 141 that define the two-surface width of the two-chamfered shaft portion 139 of the output piston 62 are the contact planes formed in the opening portion 138 of the thrust transmission portion 82 of the power piston 81. Since the output piston 62 is prevented from rotating by being slidably brought into contact with 142, 143, the output piston 62 can be prevented from rotating without impeding the propulsion (tilt) of the power piston 81.

Although the details of the present embodiment have been described above, the operational effects of the present embodiment are described below.
According to the present embodiment, the input member that moves in accordance with the operation of the brake pedal, the electric motor that operates according to the displacement of the input member, and the rotation / linear motion conversion mechanism that converts the rotational force of the motor into the thrust of the linear motion member A piston that is connected to the linear motion member and receives a linear motion thrust that is connected to the thrust transmission member and is transmitted to the thrust transmission member. An output member that transmits the linear motion thrust to the shaft, and a detected member that detects the displacement of the input member. The thrust transmission member is configured to receive the linear motion thrust from the linear motion member, and the output member is a thrust The thrust transmission member is configured so as to allow tilting of the thrust transmission member when the thrust transmission member is non-rotatable with respect to the transmission member and when the thrust transmission member receives the linear motion thrust from the linear motion member at at least one contact portion. Supported.

  Therefore, in this embodiment, the output member can be prevented from rotating without hindering the propulsion of the thrust transmission member, and the reliability of the electric booster can be improved. Further, the rotation of the output member, and hence the rotation around the axis of the detected member that slidably contacts the output member is suppressed, so that the detection accuracy of the displacement of the input member is improved, and the electric motor It is possible to accurately control the pedal and improve the pedal feeling. Furthermore, since a trapezoidal screw can be applied to the rotating member of the rotation / linear motion converting mechanism, the manufacturing cost can be reduced and the degree of freedom of layout can be reduced compared to the electric booster in which a ball screw is applied to the rotating member. Since it increases, it is possible to reduce the size.

  Further, the thrust transmission member is provided with two contact portions so as to receive the linear motion thrust from the linear motion member, and the output member has a cylindrical shape through which the input member is inserted, and has two locations. Since the surface parallel to the straight line connecting the contact parts is formed on the outer periphery, the rotation of the output member is prevented by inhibiting the rotation around at least one of the surfaces formed on the outer periphery. Can do.

  In addition, since the thrust transmission member has a contact plane that contacts the surface formed on the outer periphery of the output member, the thrust force can be increased by bringing the corresponding contact surface into contact with the surface formed on the outer periphery of the output member. The rotation of the output member relative to the transmission member can be prevented.

  Between the thrust transmission member and the output member, a linear gap connecting the two contact portions is formed. Therefore, while preventing the output member from rotating with respect to the thrust transmission member, the thrust transmission member is at least The inclination of the thrust transmission member when the linear motion thrust is received from the linear motion member at one contact portion can be allowed.

As mentioned above, although one Embodiment of this invention was described, it can comprise as follows, for example.
In the present embodiment, the thrust transmission member is configured to receive the linear motion thrust from the linear motion member at two abutting portions arranged symmetrically with respect to the axis of the master cylinder as an axis of symmetry. Can be one place. That is, the thrust transmission member is transmitted with a linear thrust from a single linear motion member. In this case, the electric booster can be further downsized.

DESCRIPTION OF SYMBOLS 1 Electric booster, 2 Master cylinder, 5 Primary piston (piston), 60 rotation linear motion conversion mechanism, 62 Output piston (output member), 64 Input piston (input member), 81 Power piston (thrust transmission member), 91 Electric motor (electric motor), 94, 95 Nut member (linear motion member), 112, 113 Contact surface (contact portion), 132 Sensor magnet (detected member)

Claims (4)

An input member that moves as the brake pedal is operated;
An electric motor that operates according to the displacement of the input member;
A rotation / linear motion conversion mechanism that converts the rotational force of the electric motor into thrust of the linear motion member;
A thrust transmission member connected to the linear motion member and capable of transmitting a linear thrust from the linear motion member;
An output member connected to the thrust transmission member, receiving the linear motion thrust transmitted to the thrust transmission member, and transmitting the linear motion thrust to the piston of the master cylinder;
A detected member for detecting the displacement of the input member,
The thrust transmission member is configured to receive a linear thrust from the linear motion member,
The output member is non-rotatable with respect to the thrust transmission member, and the thrust transmission member receives the linear motion thrust from the linear motion member at the at least one contact portion. An electric booster supported by the thrust transmission member so as to allow inclination. The thrust transmission member is provided with the two contact portions so as to receive the linear motion thrust from the linear motion member,
2. The output member according to claim 1, wherein the output member has a cylindrical shape into which the input member is inserted, and a surface parallel to a straight line connecting the two contact portions is formed on the outer periphery. The electric booster described.   The electric booster according to claim 2, wherein the thrust transmission member has a contact plane that contacts a surface formed on an outer periphery of the output member.   4. The electric booster according to claim 2, wherein a linear gap connecting the two contact portions is formed between the thrust transmission member and the output member. 5. .

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