JP6811681B2 - Electric booster - Google Patents

Description

The present invention relates to an electric booster that utilizes the thrust generated by an electric actuator as a booster.

Some electric boosters transmit the linear thrust of a power piston (thrust transmission member) to the piston of the master cylinder via an output piston (output member) connected to the power piston. In such an electric booster, it is conceivable to suppress the deviation of the stroke sensor magnet in the rotation direction with respect to the Hall IC (relative movement around the input rod axis) by stopping the rotation of the output piston. For example, Patent Document 1 discloses a structure for detenting a hollow screw shaft as a booster member, but in an electric booster provided with a power piston, the propulsion of the power piston is not hindered. , It is required to stop the output piston from rotating.

Japanese Unexamined Patent Publication No. 2014-69678

An object of the present invention is to provide an electric booster capable of stopping the rotation of an output member without hindering the propulsion of the thrust transmitting member.

In order to solve the above problems, the electric booster of the present invention linearly drives an input member that moves with the operation of the brake pedal, an electric motor that operates according to the displacement of the input member, and the rotational force of the electric motor. A rotary linear motion conversion mechanism that converts the thrust of a member, a thrust transmission member that is connected to the linear motion member and transmits the linear motion thrust from the linear motion member, and a thrust transmission member that is connected to the thrust transmission member and is connected to the thrust transmission member. The thrust transmitting member includes an output member that receives the linear thrust transmitted to the master cylinder and transmits the linear thrust to the piston of the master cylinder, and a member to be detected that detects the displacement of the input member. Two contact portions are provided so as to receive linear thrust from the moving member, and the output member has a tubular shape through which the input member is inserted and connects the two contact portions. A surface parallel to the straight line is formed on the outer periphery, the thrust transmitting member cannot rotate around the axis of the output member with respect to the thrust transmitting member, and the thrust transmitting member is at least one of the two contact portions . It is characterized in that it is supported by the thrust transmitting member so as to allow the tilt of the thrust transmitting member when a linear thrust is received from the linear driving member at the contact portion.

According to the present invention, the output member can be stopped from rotating without hindering the propulsion of the thrust transmitting member.

It is sectional drawing of the master cylinder connected to the electric booster of this embodiment, and is the figure which shows the cross section AA in FIG. It is sectional drawing of the master cylinder connected to the electric booster of this embodiment, and is the figure which shows the sectional line BB in FIG. It is a front side view of the master cylinder connected to the electric booster of this embodiment. It is a disassembled perspective part of the main part of the electric booster of this embodiment. It is an enlarged view of the main part in FIG. It is an enlarged view of the main 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.

It will be described with reference to the figure attached with one embodiment of the present invention.
1 and 2 are cross-sectional views taken along the axis plane of the electric booster 1 according to the present embodiment. In the following, for convenience, the left and right directions in FIGS. 1 and 2 are the front direction (front side) and the rear direction (rear side) of the electric booster 1, and the upward and downward directions in FIG. 1 are electric. It will be described as an upward direction and a downward direction in the booster 1.

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

The cylinder body 3 has a primary chamber 7 defined by a cylinder bore 4, a primary piston 5, and a 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 working fluid pressure (referred to as “hydraulic pressure” for convenience) to the wheel cylinders of each wheel of the vehicle via a port (not shown) provided in the cylinder body 3. It is 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.

An annular seal grooves 12 and 13 provided at regular intervals in the front-rear direction are formed on the inner peripheral surface of the cylinder bore 4. 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. An annular seal grooves 16 and 17 provided at regular intervals in the front-rear direction are formed on the inner peripheral surface of the cylinder bore 4. Seal rings 18 and 19 for sealing between the cylinder bore 4 and the secondary piston 6 are provided in the seal grooves 16 and 17. 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 in the non-braking position (see FIGS. 1 and 2), the primary chamber 7 passes through the port 20 provided on the side wall on the front side of the primary piston 5 and the port 10 of the cylinder body 3. Then, it communicates with the reservoir 9. When the primary piston 5 advances 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 cut off. As a result, the hydraulic pressure in the primary chamber 7 rises. The amount of movement of the primary piston 5 from the non-braking position of the primary piston 5 to the interruption of 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 in the non-braking position (see FIGS. 1 and 2), the secondary chamber 8 has a reservoir via a port 21 provided on the front side wall of the secondary piston 6 and a port 11 of the cylinder body 3. It communicates with 9. When the secondary piston 6 advances 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 cut off. As a result, the hydraulic pressure in 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. Has a shaft member 26 fixed to the locking member 24 and restricted from moving in the front-rear direction with respect to the locking member 25 at the other end. The compression coil spring 23 is interposed between the locking members 24 and 25, and the primary spring assembly 22 is compressible 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 a non-braking state (see FIGS. 1 and 2). Be 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 at a recess on the front side of the secondary piston 6, and one end of the locking member. It has a shaft member 31 fixed to 30 and 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 is compressible against the spring force of the compression coil spring 28.

The electric booster 1 has a housing 41 that houses a mechanical portion of an electric actuator 61, which will be 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 the front end portion of the cylindrical portion 46 of the base member 45, which will be 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 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, the front housing 42 and the cylindrical portion 46 of the base member 45 are sealed by the sealing member 49.

At the center of the rear housing 43, a cylindrical portion 50 coaxial with the cylinder bore 4 of the master cylinder 2 is formed. A substantially cylindrical (cylindrical) output piston 62 (output member) is slidably fitted to 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 of the input rod 33 is fitted to the rear end of the input piston 64, and the rear end of the input rod 33 is connected to the brake pedal 39 via a 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 this 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 surface 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 the compression coil spring 35 interposed between the spring receiving portion 37 formed on the input rod 33 and the spring receiving member 36. The brim 67 (rear end portion) of the input piston 64 is slidably fitted to the large diameter portion 63C of the output piston 62, and the 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 penetrates the output piston 62 in the vertical direction. As a result, the input piston 64 is allowed to move relative to the output piston 62 in the front-rear direction by the amount of 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 backward with respect to the rear housing 43 by abutting the stopper 68 mounted on the annular groove 131 against the opening peripheral edge portion 50A on the front side of the cylindrical portion 50 of the rear housing 43. Will be done.

The displacement of the input rod 33, and thus the displacement of the input piston 64, is detected by the 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. With reference to FIGS. 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. The flat surface 141 of the output piston 62, which will be described later, is provided with a step on which a sliding surface 133 is formed so that the bottom surface of the sensor magnet 132 slidably contacts. A groove 137 extending 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). As a result, the sensor magnet 132 is arranged 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 (propulses) the primary piston 5 of the master cylinder 2. The output rod 70 is composed of a shaft portion 71 whose front end is in contact with a mortar-shaped bottom portion 32 of a 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. To. The pressure receiving portion 72 has a bottomed cylindrical base portion 73 having an open rear side, and a support column 74 extending from the center of the base portion 73 in the front direction (master cylinder 2 side) to support the shaft portion 71. The front end portion 62A of the output piston 62 is slidably fitted inside the base portion 73. The shaft portion 71 of the output rod 70 and the support column 74 (pressure receiving portion 72) are connected by a screw 75. In other words, the shaft length (total length) of the output rod 70 is adjusted by the screw 75.

A reaction disc 76 made of an elastic material is provided between the output piston 62 and the output rod 70. The reaction disc 76 is housed 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 portion 62A of the output piston 62. In the non-braking state (see FIGS. 1 and 2), there is a so-called jump-in clearance between the rear end surface of the reaction disc 76 and the top of the input piston 64 having a conical front end. A gap is provided.

A spring receiving member 78 is provided so as to cover the base portion 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 and. As a result, the output piston 62 is urged in the rear direction and comes into contact with the 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 the annular sealing member 80.

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

Referring to FIGS. 5 and 6, a flange receiving portion 89 for receiving the flange portion 88 of the output piston 62 is provided inside the thrust transmitting portion 82 of the power piston 81. The flange receiving portion 89 is provided between the spring receiving portion 86 of the thrust transmitting portion 82 and the opening 138 described later, and is composed of a funnel-shaped inclined surface whose diameter is reduced in the rear direction. 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 has a spherical shape, in other words, the axial plane of the output piston 62. It is composed of a convex surface 90 having an arcuate cross section. That is, the output piston 62 is in contact with the flange receiving portion 89 of the power piston 81 at the spherical contact surface 90.

Referring to FIGS. 1 and 2, the electric actuator 61 has an electric motor 91 (electric motor) and a rotation linear motion conversion mechanism 60 that converts the power (rotational force) of the electric motor 91 into the thrust of the power piston 81. .. The rotary linear motion conversion mechanism 60 includes two screw shaft members 92, 93 having a rotary axis at a position different from the central axis of the master cylinder 2, and nut members 94, 95 (straight) meshed with the screw shaft members 92, 93. It has a moving member). The screws formed on the screw shaft members 92 and 93 and the nut members 94 and 95 in this embodiment are trapezoidal screws.

The screw shaft member 92 is arranged above the central axis of the master cylinder 2 and parallel to 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 the radial bearing 98 and the 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 the combination of the radial bearing 98 and the thrust bearing 99 coaxial with the radial bearing 98.

The hub 101 is fixed to the front end 100 of the screw shaft member 92. The hub 101, and thus the front end 100 of the screw shaft member 92, is rotatably supported by the base member 45 via a radial bearing 102. That is, the screw shaft member 92 is rotatably supported around the rotation axis of the screw shaft member 92 by a pair of radial bearings 98 and 102 and one thrust bearing 99. A driven pulley 104 is attached to the front end 103 of the hub 101 so that it cannot rotate relative to each other. 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 housed in a bearing accommodating portion 52 provided in the base member 45. The radial bearing 98 and the thrust bearing 99 are housed in a bearing accommodating portion 56 provided in the rear housing 43. The upper end 53 and the lower end 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 flanged hexagon nut having a flange portion 106 formed at the rear end. The front side surface 107 of the flange portion 106 (referred to as "pressing surface 107" for convenience) is parallel to a plane forming a right angle to the axis of the nut member 94 that coincides with the rotation axis of the screw shaft member 92. Eggplant. The pair of surfaces 109, 110 that determine the width across flats of the hexagonal portion 108 of the nut member 94 are slidably fitted into 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 portion 111 extends in the vertical direction and has an upper end opened.

The rear surface 112 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 cross section of the piston 81 on the axial plane is formed into a convex arc shape. That is, the power piston 81 is in contact with the pressing surface 107 of the nut member 94 at the contact surface 112 formed in an arc shape having a convex cross section on the axial plane. As a result, the lever 83 of the power piston 81 can slide and swing with respect 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 vertically symmetrically configured. Therefore, for the purpose of simplifying the description of the specification, the description of the support structure of the screw shaft member 93, the nut member 95, and the connection structure between the nut member 95 and the lever 84 of the power piston 81 will be omitted.

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

The power piston 81 (thrust transmitting member) has two contact portions, that is, the contact surface 112 at the upper end of the lever 83 and the contact surface 113 at the lower end of the lever 84, and the nut members 94 and 95 (straight). It is configured to receive linear thrust from the moving member). That is, the pressing surfaces 107 of the nut members 94 and 95 press the contact surfaces 112 and 113 of the levers 83 and 84 of the power piston 81. 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 flange receiving portion 89 of the power piston 81 presses the contact surface 90 of the flange portion 88 of the output piston 62, whereby the output piston 62 is propelled (advanced) against the spring force of the compression coil spring 77. Will be 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 disc 76.

Next, a structure for stopping 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 tubular bichamfered shaft portion 139 extending rearward from the rear end of the flange portion 88. A pair of flat surfaces 140, 141 arranged so as to sandwich the shaft hole 63 and the stopper groove 69 are formed on the outer periphery of the two-chamfered shaft portion 139. The planes 140 and 141 are arranged parallel to a straight line connecting two contact surfaces 112 and 113 (contact portions) with the nut members 94 and 95 of the power piston 81 (thrust transmission member). The distance between the axis of the output piston 62 and the plane 140 is the same as the distance between the axis of the output piston 62 and the plane 141, but the distance is not limited to the same.

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 double chamfered hole through which the double chamfered shaft portion 139 of the output piston 62 is slidably inserted. Inner surfaces 146 and 147 corresponding to outer surfaces 144 and 145, which are a part of the outer peripheral surface of the output piston 62, are formed between the facing contact planes 142 and 143 of the opening 138. A notch 150 for inserting the sensor magnet 132 is formed in the contact plane 143 of the opening 138.

Gap 148,149 (see FIG. 5) are provided between the outer surfaces 144 and 145 of the output piston 62 and the inner surfaces 146 and 147 of the power piston 81. The gaps 148 and 149 are the power piston 81 when the power piston 81 receives a linear thrust from the nut members 94 and 95 (linear motion members) at the contact surfaces 112 and 113 (two contact points). The tilt in the front-rear direction, that is, the movement difference between the nut members 94 and 95 due to the assembly error of the electric actuator 61 and the like can be tolerated.

In the electric booster 1 of the first embodiment, when the brake pedal 39 is operated, the input rod 33 advances against the urging force of the compression coil spring 35. The amount of operation 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) mounted on the input piston 64 (input member) via the pin 134, and the rear housing 43. It is measured by detecting with a Hall IC (not shown) attached to the housing. 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 eventually 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 disc 76, and the output rod 70.

When the primary piston 5 advances, the electronic control unit 114 controls the electric motor 91 so that the amount of movement of the primary piston 5 follows the displacement of the input rod 33, that is, the amount of operation of the brake pedal 39. As the primary piston 5 advances, the hydraulic pressure in the primary chamber 7 rises, 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 cylinders of each wheel of the vehicle via the two hydraulic circuits, so that a braking force due to friction braking is generated. The reaction force due to 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 disc 76.

Then, the ratio of the pressure receiving area of the front end surface of the output piston 62 to the pressure receiving area of the piston portion 65 of the input piston 64 becomes the boosting ratio (ratio of the hydraulic pressure output to the operation input of the brake pedal 39), which is desired. 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 to retract the nut members 94 and 95, and thus the power piston 81. Along with this, the primary piston 5 and the secondary piston 6 are retracted via the output piston 62, the reaction disc 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) It is necessary to prevent the output piston 62 from rotating with respect to the housing 41 in order to suppress the displacement of the rotation direction (axis circumference) with respect to the housing 41 (rear housing 43). Like the electric booster 1 of the present embodiment, the power piston 81 receives a linear thrust from the nut members 94 and 95 (linear motion members) at the contact surfaces 112 and 113 (two contact points). Then, the output piston 62 is stopped from rotating without hindering 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 stop 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 the present embodiment, the planes 140 and 141 that determine the width across flats of the chamfered shaft portion 139 of the output piston 62 are formed in the opening 138 of the thrust transmission portion 82 of the power piston 81. Since the output piston 62 is prevented from rotating by slidably contacting 142 and 143, the output piston 62 can be stopped from rotating without hindering the propulsion (tilt) of the power piston 81.

The details of the present embodiment have been described above, but the effects of the present embodiment are shown below.
According to the present embodiment, an input member that moves with the operation of the brake pedal, an electric motor that operates according to the displacement of the input member, and a rotary linear motion conversion mechanism that converts the rotational force of the electric motor into the thrust of the linear motion member. , A thrust transmission member connected to the linear motion member and transmitting the linear thrust from the linear motion member, and a piston of the master cylinder receiving the linear thrust force connected to the thrust transmission member and transmitted to the thrust transmission member. It includes an output member that transmits a linear thrust to, and a member to be detected that detects the displacement of the input member. The thrust transmission member is configured to receive a linear thrust from the linear thrust member, and the output member is a thrust. The thrust transmission member is non-rotatable with respect to the transmission member and allows the thrust transmission member to tilt when it receives a linear thrust from the linear motion member at at least one contact point. Be supported.

Therefore, in the present embodiment, the output member can be stopped rotating without hindering the propulsion of the thrust transmission member, and the reliability of the electric booster can be improved. Further, since the rotation of the output member and the rotation of the member to be detected that slidably abuts on the output member around the axis are suppressed, the accuracy of detecting the displacement of the input member is improved, and by extension, the electric motor. It is possible to control the pedal accurately, and the pedal feeling can be improved. Further, since the trapezoidal screw can be applied to the rotating member of the rotary linear motion conversion mechanism, the manufacturing cost is reduced and the degree of freedom of layout is increased as compared with the electric booster in which the ball screw is applied to the rotating member. It is possible to reduce the size by increasing the number.

Further, the thrust transmission member is provided with two contact portions so as to receive the linear thrust from the linear motion member, and the output member has a tubular shape through which the input member is inserted and is provided at two locations. Since a surface parallel to the straight line connecting the contact portions of the above is formed on the outer circumference, the output member is prevented from rotating by suppressing the rotation of at least one of the surfaces formed on the outer circumference around the axis. Can be done.

Further, since the thrust transmission member has a contact plane that abuts on the surface formed on the outer periphery of the output member, the thrust is obtained by abutting the corresponding contact surface on the surface formed on the outer periphery of the output member. It is possible to prevent the output member from rotating with respect to the transmission member.

Since a linear gap connecting the two contact portions is formed between the thrust transmission member and the output member, at least the thrust transmission member can prevent the output member from rotating with respect to the thrust transmission member. It is possible to allow the tilt of the thrust transmission member when a linear thrust is received from the linear motion member at one contact portion.

Although one embodiment of the present invention has been described above, for example, it can be configured as follows.
In the present embodiment, the thrust transmission member is configured to receive the linear thrust from the linear motion member at two contact sites arranged vertically symmetrically with the axis of the master cylinder as the axis of symmetry. Can be in one place. That is, in the thrust transmission member, the linear thrust is transmitted from a single linear motion member. In this case, the electric booster can be made smaller.

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 part), 132 sensor magnet (detected member)

Claims (3)

Input members that move with the operation of the brake pedal,
An electric motor that operates according to the displacement of the input member,
A rotary linear motion conversion mechanism that converts the rotational force of the electric motor into the thrust of the linear motion member,
A thrust transmission member connected to the linear motion member and to which a linear thrust force is transmitted from the linear motion member.
An output member connected to the thrust transmission member, receiving the linear thrust transmitted to the thrust transmission member, and transmitting the linear thrust to the piston of the master cylinder.
A member to be detected that detects the displacement of the input member is provided.
The thrust transmission member is provided with two contact portions so as to receive the linear thrust from the linear motion member.
The output member has a tubular shape through which the input member is inserted, and a surface parallel to a straight line connecting the two contact portions is formed on the outer circumference of the output member, and the output member is formed with respect to the thrust transmission member. the thrust transmission member when the non-rotatable about the axis, and the thrust transmission member which has received the linear thrust from the linear motion member with at least one place of the abutting portions of the two contact sites An electric booster characterized in that it is supported by the thrust transmitting member so as to allow the inclination of. The electric booster according to claim 1 , wherein the thrust transmission member has a contact plane that abuts on a surface formed on the outer periphery of the output member. The electric booster according to claim 1 or 2 , wherein a linear gap connecting the two contact portions is formed between the thrust transmission member and the output member. ..

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