JP2012035814A - Electric booster - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the occurrence of vibration and noise by increasing the supporting rigidity of the case of a controller which is integrally mounted on the upper part of the housing of an electric motor in an electric booster.SOLUTION: An input rod 34 and an input piston 32 are advanced by operating a brake pedal to drive the electric motor 40 according to the movement of the input piston 32. A primary piston 10 is driven forward through a ball screw mechanism 41 to generate a desired brake fluid pressure in a master cylinder 2. The case 90 of the controller C is integrally mounted on the upper part of the housing 4 so as to be laterally offset to the center axis of the master cylinder 2 and to project in the axial direction of the master cylinder 2. An arm section 100 which extends forward and has a rib 110A joined to the case 90 is formed on the housing 4 so as to support the case 90. Since the supporting rigidity of the case 90 is increased by the arm section 100, the occurrence of vibration and noise can be suppressed.

Description

  The present invention relates to an electric booster using an electric actuator as a boost source in a booster incorporated in a brake device of a vehicle such as an automobile.

  For example, Patent Document 1 discloses an input piston coupled to a brake pedal, an electric motor that is a boost source, a ball screw mechanism that converts rotational motion of the electric motor into linear motion, and a booster that is propelled by the electric motor via the ball screw mechanism. An electric booster is described in which a control unit for controlling an electric motor is integrally attached to an upper portion of a cylindrical housing that accommodates a piston or the like and is connected to a master cylinder. In this electric booster, the rear part of a substantially rectangular parallelepiped control unit arranged laterally offset from the central axis of the master cylinder is connected to the housing, and the front part is attached to the upper part of the reservoir attached to the upper part of the master cylinder. It extends forward to cover it. This avoids interference between the electric booster and other components in the engine room, thereby increasing the space efficiency in the engine room.

JP 2009-202867 A

  The electric booster described in Patent Document 1 has the following problems. Since the rear part of the control unit is connected to the motor casing and the front part extends forward, the control unit is cantilevered by the casing, the support rigidity is insufficient, the resonance frequency is lowered, and the vibration is reduced. It is easy to generate noise.

  It is an object of the present invention to provide an electric booster that increases the support rigidity of a case that accommodates a controller and suppresses the generation of vibration and noise.

  In order to solve the above-described problems, the present invention activates an electric motor by a control signal from a controller, and converts the rotational motion of the rotor of the electric motor into linear motion by a rotation-linear motion conversion mechanism to propel the piston. In the electric booster that generates the brake fluid pressure in the master cylinder, the case that accommodates the controller is integrally attached to an upper portion of the housing that accommodates the electric motor and is attached to the master cylinder. It is offset laterally with respect to the central axis of the cylinder, and is arranged so as to protrude from the housing along the axial direction of the master cylinder, and the housing has an axial direction of the master cylinder of the case A support portion is formed that extends along the protruding direction and is coupled to the case to support the case. And wherein the Rukoto.

  According to the electric booster according to the present invention, it is possible to increase the support rigidity of the case that accommodates the controller and suppress the generation of vibration and noise.

It is a longitudinal cross-sectional view which shows the state connected with the master cylinder of the electric booster which concerns on one Embodiment of this invention. It is a longitudinal cross-sectional view of the electric booster shown in FIG. FIG. 3 is a plan view of the electric booster shown in FIG. 2. FIG. 3 is a front view of the electric booster shown in FIG. 2. It is a longitudinal cross-sectional view of the motor assembly which incorporated the electric motor in the motor housing of the electric booster shown in FIG. FIG. 6 is a front view of the motor assembly shown in FIG. 5. FIG. 6 is a rear view of the motor assembly shown in FIG. 5. FIG. 6 is a plan view of the motor assembly and the seal member shown in FIG. 5. FIG. 6 is a perspective view of the motor assembly shown in FIG. 5. It is a longitudinal cross-sectional view of the front housing of the motor assembly shown in FIG. FIG. 6 is a front view of a front housing of the motor assembly shown in FIG. 5. FIG. 6 is a rear view of the front housing of the motor assembly shown in FIG. 5. FIG. 6 is a plan view of a front housing of the motor assembly shown in FIG. 5. It is a cross-sectional view by the AA line of FIG. It is a longitudinal cross-sectional view by the BB line of FIG. It is a longitudinal cross-sectional view of the rotor of the electric motor of the electric booster shown in FIG. It is a side view which shows the state before attaching the magnet cover of the rotor shown in FIG. FIG. 17 is a rear view of the rotor shown in FIG. 16. FIG. 17 is a longitudinal sectional view showing a state where a ball screw mechanism is incorporated in the rotor shown in FIG. 16. FIG. 17 is a side view of a fixing ring for attaching a ball screw mechanism to the rotor shown in FIG. 16. It is a rear view of the fixing ring shown in FIG.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
1 to 4 show an electric booster 1 according to the present embodiment, and FIG. 1 shows a state in which a clevis 73 for connecting to a master cylinder 2 and a brake pedal (not shown) is attached. ing.

  As shown in FIGS. 1 to 4, in the electric booster 1, a case 90 that accommodates the controller C is integrally attached to an upper portion of the housing 4 that houses the actuator 3. A tandem master cylinder 2 is connected to the front portion of the housing 4, and a reservoir 5 is connected to the upper portion of the master cylinder 2. The housing 4 accommodates the actuator 3 by fitting a rear cover 4B to the opening side of the substantially bottomed cylindrical front housing 4A and connecting it with a plurality of bolts 4C.

  The master cylinder 2 includes a cylinder body 2A having a substantially bottomed cylindrical shape, and an opening side of the master cylinder 2 is coupled to an opening at the bottom of the housing 4 by a stud bolt 6A and a nut 6B. A flat mounting seat surface 7 is formed on the rear cover 4B of the housing 4, and a cylindrical portion 8 concentric with the master cylinder 2 protrudes from the mounting seat surface 7. The electric booster 1 is disposed in the engine room of the vehicle, extends through the cylinder portion 8 through the partition wall (dash panel) between the engine room and the vehicle compartment, and the mounting seat surface 7 as the partition wall. It is fixed by using a plurality of stud bolts 9 which are brought into contact with each other and provided on the mounting seat surface 7.

  In the cylinder main body 2A of the master cylinder 2, a cylindrical primary piston 10 whose tip is formed in a cup shape is inserted on the opening side, and a cup-shaped secondary piston 11 is inserted on the bottom side. The rear end portion of the primary piston 10 protrudes from the opening of the master cylinder 2 into the housing 4 and extends to the cylindrical portion 8 of the rear cover 4B. The primary piston 10 and the secondary piston 11 are slidably guided by annular guide members 14 and 15 disposed on both end sides of a sleeve 13 fitted in the cylinder bore 12 of the cylinder body 2A. In the cylinder body 2A, two pressure chambers, a primary chamber 16 and a secondary chamber 17, are formed by the primary piston 10 and the secondary piston 11, and hydraulic pressure ports 18 and 19 are provided in the primary chamber 16 and the secondary chamber 17, respectively. ing. Two hydraulic pressure circuits (not shown) for supplying hydraulic pressure to the brake calipers of the wheels are connected to the hydraulic pressure ports 18 and 19, respectively.

  Reservoir ports 20 and 21 for connecting the primary chamber 16 and the secondary chamber 17 to the reservoir 5 are provided on the upper side of the side wall of the cylinder body 2A. The cylinder bore 12 of the cylinder body 2A and the primary piston 10 and the secondary piston 11 are sealed by two seal members 22A, 22B and 23A, 23B, respectively. The seal members 22A and 22B are arranged so as to sandwich the reservoir port 20 along the axial direction. When the primary piston 10 is in the non-braking position shown in FIG. 1, the primary chamber 16 is provided on the side wall of the primary piston 10. The primary chamber 16 is cut off from the reservoir port 20 by the seal member 22A when the primary piston 10 moves forward from the non-braking position. Further, the seal members 23A and 23B are arranged so as to sandwich the reservoir port 21 along the axial direction, and when the secondary piston 11 is in the non-braking position shown in FIG. When the secondary piston 11 moves forward from the non-braking position, the secondary chamber 17 is blocked from the reservoir port 21 by the seal member 23A.

  A spring assembly 26 is interposed between the primary piston 10 and the secondary piston 11 in the primary chamber 16, and a compression coil spring is provided between the bottom of the master cylinder 2 in the secondary chamber 17 and the secondary piston 11. A return spring 27 is interposed. The spring assembly 26 holds a compression coil spring 28 in a predetermined compression state by a retractable retainer 29 and can be compressed against the spring force. A cylindrical spacer 29 </ b> A is interposed between the retainer 29 and an intermediate wall 30 (described later) of the primary piston 10.

  The primary piston 10 includes a cup-shaped front end portion, a cylindrical rear portion, and an intermediate wall 30 that partitions the inside in the axial direction, and a guide bore 31 is passed through the intermediate wall 30 along the axial direction. A small-diameter tip end of a stepped input piston 32 having a step portion 32A is slidably and liquid-tightly inserted into the guide bore 31. The guide bore 31 and the input piston 32 are sealed by two seal members 33A and 33B, and a passage 33 opened between the seal members 33A and 33B of the guide bore 31 is formed in the intermediate wall 30 of the primary piston 10. Is penetrated along the radial direction.

  An intermediate portion of the primary piston 10 extending into the housing 4 is inserted into a cylindrical spring receiving member 70 that fits into an opening at the bottom of the front housing 4A, and is guided to be slidable along the axial direction. . The spring receiving member 70 is connected to the cylinder bore 12 of the master cylinder 2 with an outer flange portion 71 formed at one end thereof being fitted into and fixed to the opening at the bottom of the front housing 4A. A seal member 72 attached to the inner peripheral portion of the rear end of the spring receiving member 70 seals between the primary piston 10 and a passage 33 provided in the intermediate wall 30 of the primary piston 10 opens to the inside of the seal member 72. ing.

  The rear end portion of the input piston 32 is connected to the cylindrical portion 8 of the rear cover 4B and the front end portion of the input rod 34 inserted into the rear portion of the primary piston 10, and the rear end side of the input rod 34 is connected to the outside from the cylindrical portion 8. It is extended to. A threaded portion 34B is formed at the rear end portion of the input rod 34 extended outward from the cylindrical portion 8, and a clevis 73 and a clevis 73 for connecting a brake pedal (not shown) are connected to the threaded portion 34B. A lock nut 74 as a fastening member is screwed. A flange-shaped spring receiver 35 is attached to the rear end portion of the primary piston 10, and the primary piston 10 is a return that is a compression coil spring interposed between the rear end portion of the spring receiving member 70 and the spring receiver 35. The spring 36 is biased in the backward direction. Further, the input piston 32 is in a neutral position shown in FIG. 1 by springs 37 and 38 that are compression coil springs as spring means interposed between the intermediate wall 30 of the primary piston 10 and the spring receiver 35, respectively. Is held elastically. The retracted position of the input rod 34 is such that a large diameter contact portion 34A provided at the intermediate portion of the input rod 34 is in contact with a stopper 39 protruding inward in the radial direction provided at the rear end portion of the cylindrical portion 8 of the rear cover 4A. It is defined by touching.

  In the housing 4, there is an actuator 3 including an electric motor 40 that is an electric actuator and a ball screw mechanism 41 that is a rotation-linear motion conversion mechanism that converts the rotation of the electric motor 40 into linear motion and applies thrust to the primary piston 10. Is provided. The electric motor 40 is a permanent magnet-embedded synchronous motor, and includes a stator 42 having a plurality of coils fixed by a plurality of bolts 71 to a rear step portion of the bottom of the front housing 4A, and an inner peripheral surface of the stator 42. And a plurality of permanent magnets 45A inserted in the rotor 45 and disposed along the circumferential direction. The rotor 45 extends in the axial direction from the vicinity of the bottom of the front housing 4A to the vicinity of the rear cover 4B, and both ends thereof are rotatably supported by the front housing 4A and the rear cover 4B by bearings 43 and 44. The electric motor 40 may be a synchronous motor in which permanent magnets are arranged on the surface or inside of the rotor 45, or another type of motor such as an induction motor.

  The ball screw mechanism 41 is inserted into the nut member 46, which is a rotating member fixed to the inner peripheral portion on the rear side of the rotor 45, and the nut member 46 and the cylindrical portion 8 of the housing 4, and is movable along the axial direction. A hollow screw shaft 47 that is a linear motion member that is supported so as not to rotate around the shaft, and a plurality of balls 48 that are loaded between screw grooves formed on these opposing surfaces, and a nut member As the ball 48 rolls along the screw groove by the rotation of 46, the screw shaft 47 moves in the axial direction. Note that the ball screw mechanism 41 is capable of mutually converting rotation and linear motion between the nut member 46 and the screw shaft 47.

  A known speed reduction mechanism such as a planetary gear mechanism or a differential speed reduction mechanism is interposed between the electric motor 40 and the ball screw mechanism 41 so that the rotation of the electric motor 40 is reduced and transmitted to the ball screw mechanism 41. It may be.

  The screw shaft 47 of the ball screw mechanism 41 is urged in a backward direction by a return spring 49 that is a compression taper coil spring interposed between the flange portion 71 of the spring receiving member 70, and a rear end portion thereof is a cylindrical portion of the rear cover 4B. The retracted position is regulated by abutting against a stopper 39 provided at 8. The rear end portion of the primary piston 10 is inserted into the screw shaft 47, and the retracted position of the primary piston 10 is regulated by the spring receiver 35 coming into contact with the step portion 50 formed on the inner peripheral portion of the screw shaft 47. ing. As a result, the primary piston 10 is pushed forward by the stepped portion 50 by the advancement of the screw shaft 47, and can move forward separately from the stepped portion 50. As shown in FIG. 1, the non-braking position of the primary piston 10 is defined by the step portion 50 of the screw shaft 47 in contact with the stopper 39, and the maximum length of the primary piston 10 and the spring assembly 26 in the non-braking position is determined. The retracted position of the secondary piston 11, that is, the non-braking position is defined.

  A resolver 60 that is a rotational position sensor that detects the rotational position of the rotor 45 of the electric motor 40 is provided in the housing 4. The resolver 60 includes a resolver rotor 60A fixed to the outer peripheral portion on the rear side of the rotor 45, and a resolver stator 60B attached to the rear cover 4B with bolts 61 so as to face the resolver rotor 60A.

A cylindrical cover member 76 that covers the outer periphery of the screw shaft 47 is attached to the rear end portion of the cylindrical portion 8 of the rear housing 4B.
The rear end portion of the screw shaft 47 that protrudes from the cylindrical portion 8 is formed with guide grooves 47A (see FIG. 19) that extend to the end portion along the axial direction at two locations in the diameter direction. By engaging with the guide groove 47A, the screw shaft 47 is supported so as to be movable in the axial direction and not to rotate around the axis.

  The electric booster 1 includes a brake pedal, that is, a stroke sensor that detects displacement of the input piston 32 and the input rod 34, a current sensor that detects current supplied to the electric motor 40, and primary and secondary chambers 17 and 18. Various sensors such as a hydraulic pressure sensor for detecting the hydraulic pressure are provided. The controller C is a microprocessor-based electronic control device including an ECU and a RAM, and controls the rotation of the electric motor 40 based on detection signals from these various sensors.

Next, the structure of each part of the electric booster 1 will be described in more detail with reference to FIGS. 5 to 21 in addition to FIGS.
The controller C is accommodated in a case 90 formed in a substantially L shape (see FIG. 3) in plan view by cutting out a part of a substantially rectangular parallelepiped thin in the vertical direction. The case 90 is hermetically sealed by connecting a cover 90B with a plurality of bolts 91 to an upper opening of a lower box-shaped case main body 90A. In the case 90, a substrate on which a control circuit of the controller C is mounted is accommodated. A heat dissipation fin 90 </ b> C is formed on the surface (mainly the side surface) of the case 90. The case 90 of the controller C is disposed laterally offset from the central axis of the master cylinder 2 and the housing 4, and the rear part thereof is coupled to the upper part of the front housing 4A. The front portion of the case 90 extends to the vicinity of the front end portion of the master cylinder 2 along the axial direction above the master cylinder 2. The reservoir 5 attached to the upper part of the master cylinder 2 is arranged in a space between the master cylinder 2 and the case 90, and has a shape that bulges upward in front of the case 90. 5A is attached. A connector 92 for connecting a wire harness for supplying power and transmitting / receiving various signals to the control circuit of the controller C is provided on the side surface portion of the housing 90 from the center of the case 90 that is offset in the lateral direction. . In addition, the substantially L-shaped recess in plan view of the case 90 is disposed at the front corner in the offset direction.

  The front housing 4 </ b> A constituting the housing 4 has a stepped shape in which a small diameter portion 93 is formed at a front portion to which the master cylinder 2 is attached and a large diameter portion 94 that accommodates the electric motor 40 at the rear portion. A mounting seat 95 for connecting the case 90 of the controller C is integrally formed on the upper portion of the large diameter portion 94. The mounting seat 95 protrudes from the upper side wall of the large-diameter portion 94, and a coupling surface 95A having a substantially rectangular flat surface for coupling the case 90 to the upper end surface is formed. The mounting seat 95 is offset laterally with respect to the central axis of the housing 4 corresponding to the offset case 90 of the controller C. An opening 96 that penetrates the side wall of the front housing 4A and communicates with the inside is formed in the coupling surface 95A coupled to the case 90 of the mounting seat 95. Further, an opening 90D (see FIG. 2) is provided at the bottom of the case 90 of the controller C so as to face the opening 96 of the mounting seat 95, and the inside of the housing 4 and the case 90 are passed through these openings 96 and 90D. It communicates with the inside of. A rectangular seal groove 97 is formed on the coupling surface 95A of the mounting seat 95 so as to surround the periphery of the opening 96, and a rectangular seal member 98 is fitted into the seal groove 97 so that the coupling surface 95A and the case 90 are fitted. And a foreign matter such as moisture and dust are prevented from entering the inside of the case 90 and the housing 4. As described above, since the seal member 98 having a relatively simple shape is used in order to prevent foreign matters such as moisture and dust from entering the inside of the case 90 and the housing 4, the seal member 98 is attached. Assembling into the seat 95 can be easily performed, and the manufacturing efficiency of the electric booster is improved.

  The mounting seat 95 is formed with a pair of arm portions 99 and 100 which are support portions for supporting the case 90 by extending both ends of the front portion forward. One arm portion 99 disposed on the side portion side of the front housing 4A extends substantially parallel to the axial direction of the front housing 4A, and the other arm portion 100 disposed on the center portion side extends from the arm portion 99. It extends longer than the arm part 99 with a slight angle in the spreading direction. The tips of these arm portions 99 and 100 extend to the vicinity of the projecting direction end portion of the case 90 along the axial direction of the master cylinder. Ribs 99A and 100A extend downward from the pair of arm portions 99 and 100, respectively, and are integrally coupled to the side wall of the small diameter portion 93 and the large diameter portion 94 of the front housing 4A. The rib 100A on the center side of the front housing 4A extends vertically downward with respect to the coupling surface 95A, and the rib 99A on the side portion slopes downward toward the center of the small diameter portion 93 and extends downward. 95 both lateral ends are supported. As best shown in FIGS. 1, 10 and 15, these ribs 99 </ b> A and 100 </ b> A are inclined upward from the front end portion of the small diameter portion 93 of the front housing 4 </ b> A so as to avoid the rear portion of the reservoir 5. It extends along the axial direction of the front housing 4 </ b> A to the tip portions of the portions 99 and 100.

  That is, the ribs 99A and 100A are formed to be coupled to the front housing 4A so as to extend along the radial direction from the front end portion of the small diameter portion 93 of the front housing 4A to the coupling portion of the mounting seat 95 of the large diameter portion 94. Yes. Further, the thickness (width dimension) of the ribs 99A and 100A in the lateral direction is set to be about 9 to 16% of the thickness (width dimension) with respect to the lateral dimension of the mounting seat 95. . By forming the ribs 99A and 100A in this manner, the support rigidity of the case 90 can be increased, the resonance frequency can be increased, and the generation of noise and vibration during the operation of the electric booster 1 can be suppressed. . Further, a space 99B is formed in a portion surrounded by the rib 99A, the large diameter portion 94 of the front housing 4A, and the mounting seat 95. By forming the space 99B, it is possible to transfer heat to the front housing 4A without retaining heat from the case 90. In the present embodiment, the arm portions 99 and 100 extend along the protruding direction along the axial direction of the master cylinder of the case accommodating the controller, and support the case coupled to the case and supporting the case. Is configured.

  Then, the case 90 of the controller C is mounted on the front housing 4A by screwing the bolts 102 into the four screw holes 101 provided on the both sides of the rear portion of the coupling surface 95A of the mounting seat 95 and the tip portions of the pair of arm portions 99 and 100. These are sealed by a seal member 98 to prevent foreign matter such as moisture and dust from entering the case 90 and the inside of the housing 4.

  The stator 42 of the electric motor 40 is an annular member in which three-phase coils facing a plurality of permanent magnets 45A attached to the rotor 45 are integrated, and three coils for energizing each of these three-phase coils. A bus bar 103 with integrated terminals extends radially outward so as to protrude from the opening 96 of the mounting seat 95. Then, the bearing 43 is fitted inside the small-diameter portion 93 of the front housing 4A, the stator 42 is fitted inside the large-diameter portion 94, the bus bar 103 is inserted through the opening 96, and protrudes to the outside. The stator 42 and the bearing 43 are fixed to the front housing 4A by a plurality of bolts 71 arranged along the circumferential direction.

  As shown in FIGS. 16 to 18, a cylindrical magnet holding member 104 is fitted on the outer periphery of the rotor 45 of the electric motor 40. A plurality of magnet holding members 104 are provided on one end side along the circumferential direction, and the claw portions 104A extending along the axial direction and projecting inward are engaged with the outer circumferential groove 105 of the rotor 45 in the axial direction. It is fixed. Further, the rotation of the rotor 45 around the axis is fixed by engaging the rotation-preventing protrusion 104 </ b> B projecting on the inner periphery with a key groove 106 extending in the axial direction on the outer periphery of the rotor 45. On the other end of the magnet holding member 104, positioning protrusions 104C are formed that are arranged at equal intervals along the circumferential direction and project along the axial direction.

  Each of the plurality of permanent magnets 45A is fitted and positioned between the positioning convex portion 107 protruding from the outer peripheral portion of the rotor 45 along the circumferential direction, the end portion of the magnet holding member 104, and the positioning projection 104A. And bonded to the rotor 45. In this manner, a stainless steel thin ring-shaped magnet cover 108 is fitted and bonded to the outer periphery of the plurality of magnets 45A arranged on the outer peripheral portion of the rotor 45.

  Further, the resolver rotor 60A is fixed by fitting the ring-shaped resolver rotor 60A from the rear side of the rotor 45 and press-fitting the stopper ring 109. The resolver rotor 60A is positioned in the direction around the axis by engaging an anti-rotation protrusion protruding inward with a key groove of the rotor.

  The bearing 44 and the resolver stator 60B are assembled in the rear cover 4B, the rotor 45 is inserted into the front housing 4A in which the bearing 43 and the stator 42 are assembled, and the resolver connector 110 connected to the resolver stator 60B is connected to the front as shown in FIG. The front housing 4A and the rear cover 4B are joined by bolts 4C through the opening 96 of the housing 4A and extending to the outside.

  When the case 90 of the controller C is attached to the housing 4, the bus bar 103 protruding from the opening 96 of the mounting seat 95 of the front housing 4A is coupled to the terminal of the control circuit board of the controller C housed in the case 90, and the resolver connector 110 is connected. Are connected to corresponding connectors inside the case 90.

  Referring to FIGS. 19 to 21, the ball screw mechanism 41 is inserted into the rotor 45 of the electric motor 40, and the nut member 46 is fitted to the inner peripheral portion of the rotor 45 to be formed on the inner peripheral portion of the rotor 45. The shaft 45 abuts on the stepped portion 45 </ b> C and is positioned in the axial direction, and the rotation around the axis is fixed by the engagement between the keyway and the key or the spline connection. The nut member 46 is fixed to the rotor 45 by screwing an annular fixing ring 111 having a threaded portion 111 </ b> A formed on the outer peripheral portion thereof into the inner peripheral portion of the rotor 45. An outer peripheral groove 111B is formed in the fixing ring 111, and an O-ring 112 is fitted in the outer peripheral groove 111B to seal between the rotor 45 and the fixing ring 111. An adhesive 113 (see the cross-hatched part in FIG. 20) is applied to the threaded part 111A as a loosening stopper. Adhesive 113 is mainly composed of epoxy resin sealed in microcapsules, the microcapsules are destroyed by the frictional force when tightening the screws, the main agent and the curing agent are mixed, and the adhesive and sealing effect is generated by the curing reaction. What to do is desirable.

Next, the operation of the electric booster 1 will be described.
When the input piston 32 is moved forward via the input rod 34 by operating the brake pedal, the displacement of the input piston 32 is detected by the stroke sensor, and the operation of the electric motor 40 is controlled by the controller C based on the displacement of the input piston 32. Then, the primary piston 10 is advanced via the ball screw mechanism 41 to follow the displacement of the input piston 32. Thereby, a hydraulic pressure is generated in the primary chamber 16, and this hydraulic pressure is transmitted to the secondary chamber 17 via the secondary piston 11. In this way, the brake hydraulic pressure generated in the master cylinder 2 is supplied to the brake calipers of the respective wheels via the hydraulic pressure ports 18 and 19 to generate a braking force. When the operation of the brake pedal is released, the input piston 32, the primary piston 10 and the secondary piston 11 are moved backward to reduce the brake fluid pressure in the master cylinder 2, and the brake pad 66 is moved backward to release the braking.
Since the primary piston 10 and the secondary piston 11 operate in the same manner, only the primary piston 10 will be described below.

  At this time, a part of the hydraulic pressure in the primary chamber 16 is received by the input piston 32, and the reaction force is fed back to the brake pedal via the input rod 34. Thereby, a desired braking force can be generated with a predetermined boost ratio. Then, by adjusting the relative position between the input piston 32 and the primary piston 10 that follows the input piston 32, the spring force of the springs 37 and 38 is applied to the input piston 32, and the reaction force on the input rod 34 is adjusted. The boost ratio can be adjusted. The boost ratio is increased by adjusting the primary piston 10 forward with respect to the input piston 32, and the boost ratio is decreased by adjusting backward. Accordingly, brake control such as boost control, brake assist control, inter-vehicle stability control, inter-vehicle control, and regenerative cooperative control can be executed.

  A pair of arm portions 99 and 100 are integrally formed on a mounting seat 95 of the front housing 4A to which the case 90 of the controller C is mounted, and ribs 99A and 100A are provided to couple the arm portions 99 and 110 and the front housing 4A. Therefore, since the support rigidity of the case 90 is increased and the resonance frequency is increased, the generation of noise and vibration during the operation of the electric booster 1 can be suppressed.

  In the above embodiment, as an example, an electric booster including a tandem master cylinder 2 having two hydraulic ports 18 and 19 has been described, but the present invention is not limited thereto, The present invention can also be applied to an electric booster in which the secondary piston 11 and the secondary chamber 17 are omitted to form a single master cylinder. Moreover, in the said embodiment, other well-known rotation-linear motion conversion mechanisms other than the ball screw mechanism 41 can also be used.

  Furthermore, in the above-described embodiment, a configuration in which both the input piston and the piston are inserted into the master cylinder 2 (a configuration in which the input piston 32 is slidably and liquid-tightly inserted into the guide bore 31 of the primary piston 10). Although it is used, it is not necessary to have a structure in which the input piston is inserted into the master cylinder. For example, the structure can be applied to a so-called by-wire type configuration in which the depression force of the brake pedal is not directly transmitted to the master cylinder.

  DESCRIPTION OF SYMBOLS 1 Electric booster, 2 Master cylinder, 4 Housing 10 Primary piston (piston), 40 Electric motor, 41 Ball screw mechanism (rotation-linear motion conversion mechanism), 90 case, C controller, 99, 100 Arm part (support part)

Claims (1)

An electric motor that activates an electric motor according to a control signal from a controller, converts a rotary motion of the rotor of the electric motor into a linear motion by a rotation-linear motion conversion mechanism, propels a piston, and generates a brake fluid pressure in a master cylinder. In the force device,
The case for housing the controller is integrally attached to an upper portion of the housing for housing the electric motor to which the master cylinder is mounted, is offset laterally with respect to the central axis of the master cylinder, and the housing Arranged so as to protrude along the axial direction of the master cylinder from
The housing is formed with a support portion that extends along a protruding direction of the case along the axial direction of the master cylinder and is coupled to the case to support the case. Boost device.

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