JP6436769B2 - Electric booster - Google Patents

Description

  The present invention relates to an electric booster that is incorporated in a brake device of a vehicle such as an automobile and generates a brake fluid pressure in a master cylinder using an electric motor.

  As a booster incorporated in a brake device, for example, as described in Patent Document 1, an electric booster using an electric motor as a boost source is known. An electric booster described in Patent Document 1 includes an input piston that moves forward and backward by operation of a brake pedal, a primary piston and a secondary piston that are arranged to be relatively movable with respect to the input piston, and a forward and backward movement of the primary piston and the secondary piston. A ball screw mechanism to be moved and an electric motor for applying a rotational force to the ball screw mechanism are provided. The brake fluid pressure is generated in the pressure chamber of the master cylinder by the thrust applied from the brake pedal to the input piston and the thrust applied from the electric motor to the primary piston and the secondary piston.

  In the electric booster described in Patent Document 1, a ball screw mechanism is accommodated in a housing, and the housing includes a front housing and a rear cover that closes an opening of the front housing. And the said electric booster is attached to the partition which partitions off between an engine room and a vehicle interior using the some stat bolt provided in the attachment seat surface of the rear cover. In addition, a bearing member that rotatably supports the rotating member of the ball screw mechanism is fixed in the vicinity of the inner side of the mounting seat surface of the rear cover (the side opposite to the stud bolt).

JP 2012-35814 A

  However, in the electric booster described in Patent Document 1, since the rear cover has a structure in which the axial force of the ball screw mechanism and the depression force to the brake pedal are applied, the rear cover needs to have high strength. If you deal with the wall thickness, etc., the result will be heavy. Furthermore, in the electric booster described in Patent Document 1, the outer periphery of the bearing member that rotatably supports the rotating member of the ball screw mechanism and the trajectory of the circumference connecting the centers of the respective stat bolts substantially coincide with each other. The cylindrical wall surface of the rear cover that supports the outer peripheral surface of the bearing member is formed with a notch recess for fixing each stat bolt. This notch recess reduces the rigidity of the rear cover, which is disadvantageous for sound vibration.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an electric booster in which the rigidity of a housing and, consequently, sound vibration performance is improved.

In order to solve the above problems, an electric booster according to the present invention is an electric booster that is attached to a vehicle and moves a piston of a master cylinder through a rotation / linear motion conversion mechanism by rotation of an electric motor. A housing in which the rotation / linear motion converting mechanism is accommodated, and a mounting plate that is provided with a bolt for mounting to the vehicle and is fixed to the housing, wherein the housing includes a front housing and a rear housing. With
A bearing member that rotatably supports the rotating member of the rotation / linear motion converting mechanism is fixed to the rear housing, and the mounting plate is more than the portion where the bearing member is fixed to the rear housing. It is characterized by being fixed to the front housing via the rear housing by a fixing screw at a position distant from the radial center to the outside in the radial direction .

  According to the electric booster according to the present invention, the rigidity of the housing and consequently the sound vibration performance can be improved.

It is sectional drawing of the electric booster which concerns on 1st Embodiment. It is a disassembled perspective view of the electric booster of FIG. It is a perspective view of the state where the stud bolt was fixed to the attachment plate employ | adopted as the electric booster of FIG.

  Hereinafter, the electric booster 1 according to the present embodiment will be described in detail with reference to FIGS. As shown in FIG. 1, the electric booster 1 according to this embodiment is a booster that uses an electric motor 2 as a drive source. The electric booster 1 has a structure in which a tandem master cylinder 4 is connected to the front side of the housing 3 (left side in the figure). A reservoir 5 (only a part of which is shown) for supplying brake fluid to the master cylinder 4 is attached to the upper part of the master cylinder 4. The housing 3 includes a front housing 3A that houses the electric motor 2, the ball screw mechanism 38, and the like, and a rear housing 3B that closes the rear end opening of the front housing 3A.

  As shown in FIG. 1, the rear housing 3 </ b> B of the housing 3 has a cylindrical portion 7 that is concentric with the master cylinder 4 and protrudes rearward (rightward in the drawing) of the housing 3, i.e., away from the master cylinder 4. Is provided. As shown in FIGS. 1 and 2, a mounting plate 65 is disposed around the cylindrical portion 7 of the rear housing 3B. A stepped portion 54 is provided around the cylindrical portion 7 of the rear housing 3B, and flat first and second mounting seat surfaces 61, 62 for fixing the mounting plate 65 around the stepped portion 54 are provided. Are projected radially outward. The first mounting seat surface 61 is formed to have a larger area than the second mounting seat surface 62. In the present embodiment, two first mounting seat surfaces 61 are formed at substantially opposite positions, and the second mounting seat surfaces 62 and 62 are adjacent to each other between the first mounting seat surfaces 61 and 61. Thus, two places are formed (only one place is shown in FIG. 2). Insertion holes 61A and 62A through which the fixing screws 55 are inserted are formed in the first and second mounting seat surfaces 61 and 62, respectively. In the present embodiment, two insertion holes 61 </ b> A are formed in the first mounting seat surface 61. One insertion hole 62 </ b> A is formed in the second mounting seat surface 62. A plurality of insertion holes 3A ′ and 3A ′ (see FIG. 1) are formed on the front surface of the front housing 3A so as to correspond to the insertion holes 61A and 62A provided in the first and second mounting seat surfaces 61 and 62, respectively. Is done.

  As shown in FIGS. 2 and 3, the mounting plate 65 includes a plate-like annular portion 66 having an opening 66 </ b> A through which the cylindrical portion 7 of the rear housing 3 </ b> B can be inserted, and a plurality of outward mounting portions from the annular portion 66. There are first and second mounting flanges 67 and 68 that project radially, and an annular portion 66 and a cylindrical wall 69 that connects each of the first and second mounting flanges 67 and 68. doing. The annular portion 66 is disposed on the rear side of the first and second attachment flanges 67 and 68. A plurality of insertion holes 66 </ b> B along the axial direction are formed in the outer peripheral portion of the annular portion 66. A plurality of insertion holes 66B are formed at intervals in the circumferential direction. In the present embodiment, four insertion holes 66B are formed. Each stud bolt 8 is inserted into each insertion hole 66B from the front of the annular portion 66, extends rearward from the annular portion 66, and is fixed to the annular portion 66. At this time, the axial length of the cylindrical wall 69 of the mounting plate 65 is formed longer than the axial length of the head 8A of the stat bolt 8.

  Each first mounting flange 67 of the mounting plate 65 is formed corresponding to each first mounting seat surface 61 of the rear housing 3B. Each second mounting flange 68 of the mounting plate 65 is formed corresponding to each second mounting seat surface 62 of the rear housing 3B. Accordingly, the first mounting flanges 67 and 67 are formed at the second positions at substantially opposite positions, and the second mounting flanges 68 and 68 are adjacent to each other between the first mounting flanges 67 and 67. Two places are formed as shown. Two insertion holes 67 </ b> A through which the fixing screws 55 are inserted are formed in the first mounting flange 67. One insertion hole 67 </ b> B through which the fixing screw 55 is inserted is formed in the second mounting flange 68. On the inner peripheral surface of the cylindrical wall portion 69, a notch recess 69 </ b> A is formed at a position where each insertion hole 66 </ b> B is formed so as to avoid interference with the head 8 </ b> A of each stat bolt 8.

  Then, after each stat bolt 8 is fixed to each insertion hole 66B of the annular portion 66 of the mounting plate 65, each fixing screw 55 is inserted into each of the first and second mounting flanges 67 and 68 of the mounting plate 65. The holes 67A and 68A are inserted through the respective holes 61A and 62A of the first and second mounting seat surfaces 61 and 62 of the rear housing 3B, and the holes 3A 'and 3A' of the front housing 3A. The mounting plate 65 is fixed to the front housing 3A via the rear housing 3B. Therefore, the diameter of the circumference connecting the center in the radial direction of each fixing screw 55 is set larger than the outer diameter of the bearing member 42 that rotatably supports a nut member 39 of a ball screw mechanism 38 described later. Further, since the axial length of the cylindrical wall portion 69 of the mounting plate 65 is longer than the axial length of the head 8A of the stat bolt 8, the mounting plate 65 is attached to the front housing 3A via the rear housing 3B. When fixed, the head 8A of the stud bolt 8 does not interfere with the rear surface of the rear housing 3B. Thereafter, the electric booster 1 has the cylindrical portion 7 penetrated through a dash panel (not shown) that is a partition wall between the engine room and the vehicle compartment of the vehicle and extended into the vehicle compartment, It arrange | positions and it fixes to the dash panel using the some stud bolt 8 via the spacer 75 (refer FIG. 1). The spacer 75 is provided according to the vehicle to which the electric booster 1 is attached, and is not necessarily provided.

  As shown in FIG. 1, a bottomed cylinder bore 9 is formed in the master cylinder 4. A substantially cylindrical primary piston 10 (piston) is disposed on the opening side of the cylinder bore 9. The front end side of the primary piston 10 is formed in a cup shape and is disposed in the cylinder bore 9. A cup-shaped secondary piston 11 is disposed on the bottom side of the cylinder bore 9. The rear end portion of the primary piston 10 extends from the opening of the master cylinder 4 into the housing 3 and extends into the cylindrical portion 7 of the rear housing 3B. In the cylinder bore 9 of the master cylinder 4, a primary chamber 12 is formed between the primary piston 10 and the secondary piston 11, and a secondary chamber 13 is formed between the bottom of the cylinder bore 9 and the secondary piston 11. Each of the primary chamber 12 and the secondary chamber 13 is connected from a hydraulic port (not shown) of the master cylinder 4 to a wheel cylinder (not shown) of each wheel via two hydraulic circuits. The

  The master cylinder 4 is provided with reservoir ports 14 and 15 for connecting the primary chamber 12 and the secondary chamber 13 to the reservoir 5, respectively. On the inner peripheral surface of the cylinder bore 9, annular piston seals 16, 17, 18, 19 for sealing between the primary piston 10 and the secondary piston 11 are mounted at predetermined intervals along the axial direction. The piston seals 16 and 17 are disposed so as to sandwich one reservoir port 14 along the axial direction. When the primary piston 10 is in the non-braking position shown in FIG. 1, the primary chamber 12 communicates with the reservoir port 14 via the piston port 20 provided on the side wall of the primary piston 10. When the primary piston 10 moves forward from the non-braking position and the piston port 20 reaches one piston seal 17, the primary chamber 16 is shut off from the reservoir port 14 by the piston seal 17 and a hydraulic pressure is generated.

  Similarly, the remaining two piston seals 18 and 19 are disposed with the reservoir port 15 interposed therebetween in the axial direction. When the secondary piston 11 is in the non-braking position shown in FIG. 1, the secondary chamber 13 communicates with the reservoir port 15 via a piston port 21 provided on the side wall of the secondary piston 11. Then, the secondary piston 11 moves forward from the non-braking position, and the secondary chamber 13 is shut off from the reservoir port 15 by the piston seal 19 to generate hydraulic pressure.

  A spring 22 is interposed between the primary piston 10 and the secondary piston 11. A spring 23 is interposed between the bottom of the cylinder bore 9 and the secondary piston 11.

  The primary piston 10 is formed in a substantially cylindrical shape as a whole, and includes an intermediate wall 24 in the center in the axial direction. A guide bore 25 passes through the intermediate wall 24 in the axial direction. An input piston 26 is slidably and liquid-tightly inserted into the guide bore 25. The input piston 26 is formed in a stepped shape including a small-diameter portion 26A located on the front side and a large-diameter portion 26B extending continuously from the small-diameter portion 26A to the rear side. A small diameter portion 26 </ b> A of the input piston 26 is slidably and liquid-tightly inserted into the guide bore 25.

  A seal 27 seals between the outer peripheral surface of the small diameter portion 26 </ b> A of the input piston 26 and the inner peripheral surface of the guide bore 25. An outer flange-shaped spring receiving portion 26 </ b> C is formed at the rear end of the large-diameter portion 26 </ b> B of the input piston 26. The outer peripheral portion of the spring receiving portion 26C is disposed close to the inner wall surface on the rear side of the primary piston 10. A guide recess 26D is formed on the rear end surface of the input piston 26. A through hole 26 </ b> E extending in the radial direction is formed in the peripheral wall portion of the large diameter portion 26 </ b> B of the input piston 26 that faces the guide recess 26 </ b> D. The input piston 26 faces the primary chamber 12 of the master cylinder 4 at the front end portion of the small diameter portion 26 </ b> A and can move relative to the primary piston 10 along the axial direction.

  An input plunger 29 is guided behind the input piston 26 inside the rear side of the primary piston 10 so as to be movable along the axial direction. The rear end portion of the input plunger 29 is connected to the front end portion of the input rod 30 by a ball joint 31 so as to allow a certain degree of inclination. A small-diameter projecting portion 29 </ b> A projects forward from the front end surface of the input plunger 29. The small-diameter projecting portion 29 </ b> A is inserted into a guide recess 26 </ b> A provided on the rear end surface of the input piston 26. The front end side of the input rod 30 connected to the input plunger 29 is disposed inside the cylindrical portion 7 and the primary piston 10 of the rear housing 3B, and the rear end side extends from the cylindrical portion 7 to the outside. A brake pedal (not shown) is connected to the rear end portion of the input rod 30 via a clevis 30A. And the input rod 30 moves to an axial direction by operation of this brake pedal. In addition, a hook-shaped stopper abutting portion 32 is formed at a substantially intermediate portion arranged in the cylindrical portion 7 of the input rod 30. A stopper 33 extending radially inward is formed at the rear end portion of the cylindrical portion 7, and the retracted position of the input rod 30 is defined by the stopper contact portion 32 of the input rod 30 coming into contact with the stopper 33. It has become so.

  A first spring 34 that is a compression coil spring is interposed between the intermediate wall 24 of the primary piston 10 and a spring receiving portion 26 </ b> C formed at the rear end portion of the input piston 26. Further, a second spring 36 that is a compression coil spring is interposed between the rear end portion of the input plunger 29 and a spring receiver 35 attached to the rear end portion of the primary piston 10. A cylindrical member 37 is disposed in a cylindrical screw shaft 40 which is a configuration of a ball screw mechanism 38 described later. The rear end portion of the cylindrical member 37 is in contact with the front surface of the outer peripheral portion of the spring receiver 35 and extends from the front end of the screw shaft 40 to a position slightly ahead. A spring receiver 37 </ b> A is formed on the front end surface of the cylindrical member 37.

  The input piston 26 and the input plunger 29 are in the neutral position shown in FIG. 1 by the first spring 34 and the second spring 36, that is, a position where the biasing force of the first spring 34 and the biasing force of the second spring 36 are balanced. Is held elastically. The input piston 26 and the input plunger 29 are movable forward and backward from the neutral position with respect to the primary piston 10.

  In the housing 3, a ball screw mechanism 38 which is a rotation / linear motion converting mechanism is accommodated. The ball screw mechanism 38 is driven by the electric motor 2 disposed in the housing 3 and functions as an assist mechanism that converts a rotational motion into a linear motion and applies thrust to the primary piston 10. The ball screw mechanism 38 has a nut member 39 and a screw shaft 40 which are rotating members. The nut member 39 is rotatably supported in the housing 3 by the bearing member 42. The bearing member 42 is fixed to the rear housing 3B.

  The screw shaft 40 is formed in a cylindrical shape. The screw shaft 40 extends from the inside of the nut member 39 to the inside of the cylindrical portion 7 of the housing 3, is movable along the axial direction, and is supported by the housing 3 so as not to rotate around the axis. The screw shaft 40 is urged in the backward direction by an urging force of a return spring 49 which is a compression coil spring interposed between a bottom portion of the front housing 3A and a spring receiver 37A provided at the front end of the cylindrical member 37. ing. On the inner peripheral surface of the nut member 39 and the outer peripheral surface of the screw shaft 40, spiral grooves 39A and 40A are formed, respectively. Between these spiral grooves 39A and 40A, a plurality of rolling elements balls 41 are loaded together with grease. The screw shaft 40 is guided by the stopper 33 of the cylindrical portion 7 so as to be movable along the axial direction, and is supported so as not to rotate around the shaft. Thereby, with rotation of the nut member 39, the ball 41 rolls along the spiral grooves 39A, 40A, and the screw shaft 40 moves in the axial direction. The ball screw mechanism 38 can mutually convert rotation and linear motion between the nut member 39 and the screw shaft 40.

  The primary piston 10 has a rear end portion inserted into the screw shaft 40, and a rear surface of the outer peripheral portion of the spring receiver 35 abuts on an annular step portion 44 formed on the inner peripheral portion of the screw shaft 40. The retraction position for is defined. Thereby, the primary piston 10 is pushed by the stepped portion 44 together with the cylindrical member 37 by the advancement of the screw shaft 40, and can be moved forward separately from the stepped portion 44.

  The electric motor 2 is housed in the housing 3 on a separate axis from the master cylinder 4, the input rod 30, and the ball screw mechanism 38. The electric motor 2 has a pulley 45A attached to its output shaft 2A. The output shaft 2A is rotatably supported in the housing 3 by bearing members 50 and 51. A pulley 45B is also attached to the nut member 39 of the ball screw mechanism 38. A belt 46 is wound around the pulley 45A of the output shaft 2A and the pulley 45B of the nut member 39. The electric motor 2 rotates the nut member 39 of the ball screw mechanism 38 via the pulleys 45A and 45B and the belt 46.

  The electric booster 1 includes a rotational position sensor (not shown) that detects the rotational position of the electric motor 2, a stroke sensor (not shown) that detects the stroke of the input rod 30, and output signals of these sensors. A microprocessor-based controller (not shown) for controlling the operation of the electric motor 2 based on the above is provided. The controller can be appropriately connected to an in-vehicle controller or the like for executing various brake controls such as regenerative cooperative control, brake assist control, and automatic brake control.

Next, the operation of the electric booster 1 will be described.
When the input rod 30 is moved forward by operating the brake pedal, the controller controls the operation of the electric motor 2 based on the operation amount of the brake pedal, that is, the stroke of the input rod 30. By rotating the nut member 39 of the ball screw mechanism 38 via the pulleys 45A and 45B and the belt 46 by the electric motor 2, the screw shaft 40 is advanced. Then, the spring receiver 35 of the primary piston 10 is pressed by the step 44 of the screw shaft 40, and the primary piston 10 moves forward to follow the stroke of the input rod 30. Thereby, a hydraulic pressure is generated in the primary chamber 12, and this hydraulic pressure is transmitted to the secondary chamber 13 through the secondary piston 11. In this way, the brake fluid pressure generated in the master cylinder 4 is supplied to the wheel cylinder of each wheel, and a braking force is generated by friction braking.

  When the operation of the brake pedal is released, the controller reversely rotates the electric motor 2 based on the stroke of the input rod 30 so that the primary piston 10 and the secondary piston 11 are retracted, and the brake hydraulic pressure of the master cylinder 4 is reduced. Thus, the braking force is released.

  When the hydraulic pressure is generated, the hydraulic pressure in the primary chamber 12 is received by the small diameter portion 26A of the input piston 26, and the reaction force is transmitted to the brake pedal via the input plunger 29 and the input rod 30, that is, fed back. Thereby, a desired braking force can be generated with a predetermined boost ratio (ratio of hydraulic pressure output to operating force of the brake pedal). The controller can control the operation of the electric motor 2 to adjust the relative position between the input piston 26 and the primary piston 10 that follows the input piston 26. Specifically, the hydraulic pressure output for the operation of the brake pedal is increased by adjusting the position of the primary piston 10 to the front, that is, the master cylinder 4 side with respect to the stroke position of the input piston 26, and the rear, By adjusting to the brake pedal side, the hydraulic pressure output for the operation of the brake pedal can be reduced. As a result, brake control such as boost control, brake assist control, inter-vehicle control, and regenerative cooperative control can be executed.

  Even if the ball screw mechanism 38 becomes inoperable due to the failure of the electric motor 2 or the controller, etc., the input piston 26 moves forward by the operation of the brake pedal, and the large-diameter portion 26B of the input piston 26 When the front end portion presses the intermediate wall 24 of the primary piston 10, a hydraulic pressure can be generated in the master cylinder 4, and the braking function can be maintained.

  As described above, according to the electric booster 1 according to the present embodiment, the mounting plate 65 provided with the stat bolt 8 for mounting on the vehicle is provided separately from the rear housing 3B, and the mounting plate 65 is provided with the mounting plate 65. Since the structure is such that the depression force to the brake pedal is received, the strength required for the rear housing 3B can be reduced, and as a result, weight reduction can be realized. Moreover, the mounting plate 65 is fixed to the front housing 3A together with the rear housing 3B by the fixing screws 55 at a position farther from the radial center of the bearing member 42 than the portion where the bearing member 42 is fixed to the rear housing 3B. The That is, the diameter of the circumference connecting the center in the radial direction of each fixing screw 55 that fixes the mounting plate 65 to the front housing 3 </ b> A together with the rear housing 3 </ b> B is set larger than the outer diameter of the bearing member 42. Thereby, it is not necessary to form a notch recess in the cylindrical wall surface for fixing the bearing member 42 of the rear cover as in the conventional case, the rigidity of the rear housing 3B can be ensured, and the sound vibration performance can be improved.

  DESCRIPTION OF SYMBOLS 1 Electric booster, 2 Electric motor, 3 Housing, 4 Master cylinder, 3A Front housing, 3B Rear housing, 8 Stat bolt, 10 Primary piston, 11 Secondary piston, 38 Ball screw mechanism (rotation linear motion conversion mechanism), 39 Nut Member (Rotating member), 42 Bearing member, 55 Fixing screw, 65 Mounting plate

Claims (1)

An electric booster that is attached to a vehicle and moves a piston of a master cylinder via a rotation / linear motion conversion mechanism by rotation of an electric motor,
A housing in which the rotation / linear motion converting mechanism is accommodated;
A bolt for mounting to the vehicle, and a mounting plate fixed to the housing;
The housing includes a front housing and a rear housing,
A bearing member that rotatably supports the rotating member of the rotation / linear motion converting mechanism is fixed to the rear housing,
The mounting plate is fixed to the front housing via the rear housing at a position farther outward from the radial center of the bearing member than the portion where the bearing member is fixed to the rear housing. An electric booster that is fixed.

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