JP2015067240A - Vacuum servo - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vacuum servo capable of satisfying both a downscaling requirement and a radiation requirement.SOLUTION: In response to manipulation of an input rod 21 by a brake pedal, a controller 130 controls a power motor 33 to thrust a piston of a master cylinder 2 to generate a brake fluid pressure. The controller 130 is arranged laterally to an axis L of the master cylinder 2 and a central axis M of the power motor 33 so as to extend vertically. Furthermore, the power motor 33 is arranged at a position at which the central axis M of the power motor 33 is on the axis L of the master cylinder 2 or is deviated from the axis L of the master cylinder 2 to an opposite side to the controller 130, thus forming a cavity C1 between the power motor 33 and the controller 130. Radiation fins 122 are provided on the controller 130. It is possible to suppress heat exchange between the controller 130 having high calorific power and the power motor 33, and to improve cooling efficiency because of the cavity C1 serving as a heat radiation passage as well as heat radiation by the radiation fins 122.

Description

  The present invention relates to an electric booster that is provided in a brake device of a vehicle such as an automobile and uses an electric motor as a booster source.

  2. Description of the Related Art An electric booster that uses an electric motor as a boost source is known in a booster that is provided in a brake device of a vehicle such as an automobile and reduces the operating force of a brake pedal. For example, as described in Patent Document 1, the electric booster controls the operation of the electric motor by a controller based on the operation amount of a brake pedal detected by a sensor, and rotates the linear motion of the electric motor. It is converted into linear motion by the conversion mechanism, and the piston of the master cylinder is propelled to generate brake fluid pressure. Then, the brake fluid pressure is supplied to the hydraulic brake of each wheel to generate a desired braking force.

JP 2013-154842 A

  In this type of electric booster, while there is a demand for downsizing from the viewpoint of mounting on a vehicle, it is necessary to ensure heat dissipation of the electric motor and the controller. For this reason, the electric booster is required to have a layout of a master cylinder, an electric motor, and a controller that achieves both small size, light weight, and heat dissipation.

  On the other hand, in what is described in Patent Document 1, an electric motor is disposed at a position offset from the central axis of the master cylinder at the upper part of the housing that houses the rotation-linear motion conversion mechanism, and the controller is disposed at the upper part of the housing. Are arranged so as to be perpendicular to the central axis of the master cylinder.

  Such a layout is advantageous for heat dissipation of the electric motor and the controller, but since the controller is arranged perpendicular to the central axis of the master cylinder, the radial size of the electric booster is increased. Does not meet the requirements for miniaturization.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an electric booster that is capable of satisfying both the requirements for downsizing and heat dissipation.

  A housing coupled to the master cylinder; an electric motor disposed in the housing; a transmission mechanism housed in the housing for transmitting the output of the electric motor to propel the piston of the master cylinder; In the electric booster comprising a control board for controlling the operation of the motor, the housing has the central axis of the electric motor along the axis of the master cylinder at a position away from the axis of the master cylinder. A motor holding unit for arranging and holding the electric motor, and a control board holding unit for arranging and holding the control board so as to face the side of the axis of the master cylinder and the central axis of the electric motor, The electric motor has a central axis of the electric motor that is separated from the control board holding portion more than the axis of the master cylinder. Next to the position, characterized in that the outer peripheral surface of the electric motor is held in the motor holding portion so that the position away from the control substrate holder.

  According to the electric booster according to the present invention, it is possible to satisfy both demands for size reduction and heat dissipation.

1 is a longitudinal sectional view of an electric booster according to an embodiment of the present invention. It is a perspective view of the electric booster shown in FIG. It is a top view of the electric booster shown in FIG. It is a front view of the electric booster shown in FIG.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
As shown in FIGS. 1 to 4, the electric booster 1 according to this embodiment is integrally coupled to a master cylinder 2 that generates brake fluid pressure, and a primary piston 72 (piston) of the master cylinder 2 is connected. Promote. The electric booster 1 accommodates an input member 31 to which a brake pedal (not shown) is coupled, an electric motor 33, a ball screw mechanism 34 that is a transmission mechanism that transmits the output of the electric motor 33 to a primary piston 72, and these. And a controller 130 integrally attached to the housing 32. The housing 32 is made of an aluminum alloy or the like, and includes a front housing 35 on the master cylinder 2 side, a rear housing 36 on the brake pedal side connected to the input rod 21, and an intermediate housing 37 coupled therebetween. It has a three-part structure. In the following description, an outline of the configuration of the intermediate housing 37 will be described in relation to the internal structure shown in FIG. 1, and the details will be described later.

  The front housing 35 has a substantially bottomed cylindrical shape, and an end portion on the opening side of the master cylinder 2 is inserted into an opening portion 35a provided at the bottom portion. A front housing 35 is coupled to one end of the intermediate housing 37. The intermediate housing 37 is coupled with an electric motor 33 arranged so that a part of the front housing 35 faces the side surface of the front housing 35. The intermediate housing 37 is press-fitted and fixed with a base end portion of a pair of through bolts 48 arranged in the diameter direction inside the intermediate housing 37. The through bolt 48 is attached to the bottom portion of the front housing 35 and the mounting portion of the master cylinder 2. The intermediate housing 37, the front housing 35, and the master cylinder 2 are integrally coupled by being inserted into 2a and screwed onto the nut 49. A rear housing 36 is coupled to the other end of the intermediate housing 37. The rear end of the rear housing 36 is fixed to a dash panel (not shown) that is a partition wall between the engine room and the vehicle compartment of the vehicle. A cylindrical portion 36a protrudes from the rear end portion of the rear housing 36, and the cylindrical portion 36a extends through the dash panel into the vehicle interior. A substantially bottomed cylindrical rear cover 110 is attached to the cylindrical portion 36a by a bolt 111.

  An input member 31 extending in the axial direction from the outside of the rear cover 110 attached to the cylindrical portion 36 a of the rear housing 36 to the master cylinder 2 is inserted into the housing 32. The input member 31 includes an input rod 21, a plunger rod 90, and an input piston 93. The input rod 21 is connected to the brake pedal by a clevis 21a attached to the base end portion.

  The proximal end portion of the plunger rod 90 and the distal end portion of the input rod 21 are connected by a ball joint 39. The ball joint 39 pivots the plunger rod 20 and the input rod 21 by fitting the ball 39b formed at the distal end portion of the input rod 21 into a ball socket 39a formed at the proximal end portion of the plunger rod 90. By attaching (pivot coupling), these inclinations are allowed. The input piston 93 has a proximal end abutted against the distal end portion of the plunger rod 90, and the distal end portion passes through the sub piston 92 and is inserted into the master cylinder 2.

  The sub-piston 92 has a stepped cylindrical shape having a large-diameter spring receiving portion 92a on the front end side and a small-diameter piston portion 92b on the rear end side, and the small-diameter portion 93d at the tip of the input piston 93 slides inside the piston portion 92b. It is movable and fluid-tightly inserted. The sub-piston 92 has a spring receiving portion 92a disposed in the master cylinder 2 and a piston portion 92b inserted into the cylindrical primary piston 72 of the master cylinder 2 in a liquid-tight and slidable manner. The tip end portion of the primary piston 72 is in contact with the stepped portion 92c between the 92a and the piston portion 92b.

  The substantially bottomed cylindrical rear cover 110 has a double cylinder structure, and a cylindrical guide portion 110a having a small diameter is integrally formed along the axial direction at the center of the bottom portion. The distal end portion of the guide portion 110a protrudes and extends from the opening end of the cylindrical side wall of the rear cover 110. With the rear cover 110 attached to the cylindrical portion 36a of the rear housing 36 by the bolt 111, the guide portion 110a extends to the inside of the housing 32 through the cylindrical portion 36a.

  The plunger rod 90 is inserted into the guide portion 110a of the rear cover 110, and is guided by the guide portion 110a so as to be slidable along the axial direction, and is supported so as not to move and tilt in the radial direction. A plurality of outer peripheral grooves 90a are formed on the sliding surface of the plunger rod 90 with the guide portion 110a to enhance the sealing performance and the sliding performance between the plunger rod 90 and the guide portion 110a. The plunger rod 90 has a large-diameter flange portion 90b formed at an intermediate portion thereof in contact with the tip end portion of the guide portion 110a to define a retracted position. The input piston 93 has a stepped shape having a small-diameter portion 93d on the distal end side, a medium-diameter portion 93a on the proximal end side, and a large-diameter flange portion 93b formed on the medium-diameter portion 93a. A step portion 93e between the diameter portion 93a and the rear end portion of the sub-piston 92 can come into contact. A reaction force adjustment spring 100 that is a compression coil spring is interposed between the rear end portion of the sub-piston 92 and the flange portion 93b. The reaction force adjusting spring 100 adjusts the reaction force to the brake pedal when the input piston 93 and the sub-piston 92 are relatively displaced.

  The electric motor 33 is a brushless DC motor that is operated by a control current from the controller 130, and drives the ball screw mechanism 34 via a rotation transmission mechanism 53 such as a belt. The rotation of the electric motor 33 is detected by a rotation detector (not shown) such as a resolver, a rotary encoder, and a Hall element, and is input to the controller 130 as a detection signal. In addition to the brushless DC motor of the present embodiment, the electric motor 33 can be a brushed DC motor, an AC motor, or the like, but a DC brushless motor is desirable from the viewpoint of controllability, silence, durability, and the like. . In the present embodiment, the rotation transmission mechanism 53 and the ball screw mechanism 34 constitute a transmission mechanism that transmits the output of the electric motor and propels the piston of the master cylinder.

  The ball screw mechanism 34 is formed between a cylindrical linear motion member 55 arranged coaxially with the primary piston 72 of the master cylinder 2, a cylindrical rotary member 57 into which the linear motion member 55 is inserted, and between them. And a plurality of rolling elements 56 (steel balls) loaded in the spiral thread groove 55a. The linear motion member 55 is inserted into the cylindrical portion 36a of the rear housing 36 and the rear cover 110 attached to the cylindrical portion 36a, is movable along the axial direction in the housing 32, and is supported so as not to rotate around the axis. Has been. The rotating member 57 is supported by the pair of bearings 51 in the housing 32 so as to be rotatable about the axis and not to move in the axial direction. Then, the ball screw mechanism 34 rotates the rotating member 57 via the rotation transmission mechanism 53 by the driving force of the electric motor 33, whereby the ball 56 rolls in the screw groove 55a and the linear motion member 55 is moved in the axial direction. It is supposed to move.

  A spring receiver 61 disposed in the front housing 35 is coupled to the front end portion of the linear motion member 55 by a C ring 63. The spring receiver 61 has a large-diameter portion 61A and a small-diameter portion 61B, and has a stepped cylindrical shape with a step portion 61C formed therebetween, and a pair of guides projecting in the diametrical direction on the outer peripheral portion of the large-diameter portion 61A. The part 64 is integrally formed. The spring receiver 61 is fixed to the linear motion member 55 in the axial direction by inserting the front end portion of the linear motion member 55 into the small diameter portion 61B and mounting the C ring 63 at the tip thereof. Further, the spring receiver 61 is coupled to the linear motion member 55 so as not to rotate about the axis by the engagement between the small diameter portion 61B and the front end portion of the linear motion member 55. As the anti-rotation of the spring receiver 61 and the linear motion member 55 around the axis, known anti-rotation means such as uneven fitting, spline, key, double chamfering, etc. can be used. The spring receiver 61 is slidably inserted in a guide hole 64A that passes through the pair of guide portions 64 along the axial direction, and is movable along the axial direction with respect to the housing 32. It is supported so as not to rotate around the axis. Thus, the linear motion member 55 is supported so as to be movable along the axial direction with respect to the housing 32 via the spring receiver 61 and not to rotate around the axis.

  A return spring 62, which is a compression coil spring, is interposed between the bottom of the front housing 35 and the spring receiver 61. The retracted position of the linear motion member 55 is defined by the stepped portion 61 </ b> C of the spring receiver 61 coming into contact with the intermediate housing 37 by the spring force of the return spring 62. The linear motion member 55 is returned to the retracted position by the spring force of the return spring 62 in a state where the driving force by the electric motor 33 does not act. In the linear motion member 55, the plunger rod 90 and the input piston 93 of the input member 31 are movably disposed.

  As the rotation transmission mechanism 53 of the electric motor 33, a belt transmission mechanism such as a toothed belt, a V belt, a metal belt, a resin belt, or other known transmission mechanisms such as a gear transmission mechanism and a chain transmission mechanism can be used. . Further, the reduction ratio may be adjusted by combining a belt transmission mechanism with a reduction mechanism such as a gear reduction mechanism. Furthermore, another transmission mechanism such as a gear speed reduction mechanism may be provided in the belt transmission mechanism to provide a backup when the belt is cut.

  The master cylinder 2 is a tandem type, and a cylindrical primary piston 72 and a bottomed cylindrical secondary piston 71 are arranged in series in the axial direction in a cylinder bore 74 inside a cylinder body 73 formed in a bottomed cylindrical shape. Has been placed. In the cylinder bore 74, a primary chamber 76 is formed between the primary piston 72 and the secondary piston 71, and a secondary chamber 75 is formed between the secondary piston 71 and the bottom of the cylinder body 73. . A sub-piston 92 is slidably and liquid-tightly inserted into the primary piston 72, and a small-diameter portion 93d of the input piston 93 is slidably and liquid-tightly inserted into the sub-piston 92. The front end portion of the primary piston 72 is in contact with the step portion 92c between the spring receiving portion 92a and the piston portion 92b of the sub-piston 92. A gap is formed between the outer periphery of the spring receiving portion 92 a and the cylinder bore 74.

  Reservoir ports (not shown) communicating with the primary chamber 76 and the secondary chamber 75 are provided at the upper part of the side wall of the cylinder body 73. A reservoir 77 for storing brake fluid is connected to these reservoir ports. The cylinder bore 74 of the cylinder body 73 is provided with a pair of piston seals 81, 82 and 79, 80 so as to sandwich each reservoir port in the axial direction. Piston seals 81, 82 and 79, 80 seal between the cylinder bore 74 and the primary and secondary pistons 72, 71. Piston ports 71 a penetrating in the radial direction are formed on the side wall of the primary piston 72 and the side wall of the cylindrical portion of the secondary piston 71.

  A pair of piston seals 96, 97 are attached to the inner peripheral groove formed in the primary piston 72 so as to sandwich the piston port 72 a in the axial direction, and seal between the sub-piston 92. A piston port 95b penetrating in the radial direction is formed on the side wall of the sub-piston 92. A piston seal 103 is attached to the inner peripheral portion of the sub piston 92 to seal between the sub piston 92 and the small diameter portion 93 d of the input piston 93. The piston seal 103 is disposed on the rear end side of the sub piston 92 with respect to the piston port 95b. The piston port 95b is always in communication with the primary chamber 76 regardless of the position of the input piston 93.

  In the primary chamber 76, a return spring 99 that is a compression coil spring interposed between the secondary piston 71 and the sub-piston 92 is provided. The return spring 99 urges the primary piston 72 and the sub piston 92 toward the retracted position by the spring force, and the step 92 c of the sub piston 92 is brought into contact with the front end of the primary piston 72. A retractable retainer 102 is inserted into the return spring 99, and the return spring 99 is held in a predetermined compressed state by the retainer 102 and can be compressed against the spring force. The secondary chamber 75 is provided with a return spring 106 interposed between the bottom of the cylinder body 73 and the secondary piston 71. The return spring 106 urges the secondary piston 71 toward the retracted position by the spring force. A retractable retainer 102a is inserted into the return spring 106. The return spring 106 is held in a predetermined compressed state by the retainer 102a, and can be compressed against the spring force.

  When the primary and secondary pistons 72 and 71 and the sub piston 92 are in the retracted position, the piston port 72a of the primary piston 72 is disposed between the pair of piston seals 81 and 82, and the piston port 72b of the sub piston 92 Is disposed between a pair of piston seals 96, 97. At this time, the reservoir 77 and the primary chamber 76 communicate with each other via the reservoir port. The piston port 71a of the secondary piston 71 is disposed between the pair of piston seals 79 and 80. At this time, the reservoir 77 and the secondary chamber 75 are communicated with each other via the reservoir port and the piston port 71a. Thus, brake fluid is appropriately supplied from the reservoir 77 to the primary chamber 76 and the secondary chamber 75 in response to wear of the brake pads, etc., and the brake fluid is replenished to each wheel cylinder (not shown).

  The primary piston 72 and the sub-piston 92 move forward, the primary piston 72 piston port 72a moves forward beyond one piston seal 82, the secondary piston 71 moves forward, and the piston port 71a moves beyond one piston seal 79. Then, the reservoir port and the piston ports 72a and 71a are blocked by the piston seals 82 and 79, respectively. As a result, the primary chamber 76 and the secondary chamber 75 are disconnected from the reservoir 77, and the primary chamber 76 and the secondary chamber 75 are pressurized as the primary and secondary pistons 72 and 71 advance.

  When the primary piston 72 is in the retracted position, the sub-piston 92 moves forward together with the input piston 93, and the piston port 95b of the sub-piston 92 moves beyond one piston seal 96 of the primary piston 72, the piston seal 96 causes the primary piston 72 to move forward. The piston port 72 a of the piston 72 is blocked from the primary chamber 76. Thereby, the communication between the primary chamber 72 and the reservoir 77 is cut off, and the primary chamber 76 is pressurized by the advance of the input piston 93 and the sub-piston 92.

  With respect to the primary chamber 76, the pressure receiving area A of the primary piston 72 is defined by the piston seal 82 on the outer peripheral side and the piston seal 96 on the inner peripheral side. The pressure receiving area B of the sub-piston 92 is defined by the piston seal 96 on the outer peripheral side and the piston seal 103 on the inner peripheral side. The pressure receiving area C of the input piston 93 is defined by the piston seal 103 on the outer peripheral side. The relationship between the pressure receiving areas A, B, and C of the primary piston 72, the sub piston 92, and the input piston 93 is A> B> C.

  The primary chamber 76 and the secondary chamber 75B are connected to a wheel cylinder of a hydraulic brake device for each wheel by two hydraulic circuits. In this way, by using two systems of hydraulic circuits, even if one of them fails, the braking function can be maintained by the other hydraulic circuit.

  The electric booster 1 includes a stroke sensor (not shown) that detects the amount of operation of the brake pedal, a rotation detector that detects the rotation of the electric motor 33, and a current that measures the current (motor current) flowing through the electric motor 33. Various sensors including a sensor (not shown) and a hydraulic pressure sensor (not shown) for detecting the brake hydraulic pressure of the master cylinder 2 are provided. The controller 130 and the in-vehicle controller control the electric motor 33 by receiving power supply from the vehicle power supply based on the detection of the various sensors described above.

Next, the operation of the electric booster 1 will be described.
In the master cylinder 2, the secondary chamber 76 is similarly pressurized by the pressurization of the primary chamber 75 via the secondary piston 71. Therefore, in the following description, only the operation on the primary chamber 75 side will be described.

(When not braking)
In the non-braking state, as shown in FIG. 1, the primary piston 72 is in the retracted position together with the linear motion member 55 of the ball screw mechanism 34 by the spring force of the return spring 62. Further, the sub-piston 92 is in a retracted position in which the stepped portion 92 c is positioned in contact with the front end portion of the primary piston 72 by the spring force of the return springs 99 and 106. The input piston 93 abuts on the plunger rod 90 by the spring force of the reaction force adjustment spring 100, and is in a retracted position where the flange portion 90 b of the plunger rod 90 abuts on the guide portion 110 a of the rear cover 110 and is positioned. In this non-braking state, the reservoir 77 and the primary chamber 76 communicate with each other via the reservoir port and the piston ports 72a and 95b, so the primary chamber 76 is in an atmospheric pressure state.

(During normal braking)
When the brake pedal is operated and the input piston 93 moves forward via the input rod 21 and the plunger rod 90, these displacements are detected by the stroke sensor. Upon receiving this detection signal, the controller 130 drives the electric motor 33 to reach the target position based on the displacement of the input member 31 and feeds back the rotation of the electric motor 33 according to the detection of the rotation detector. Control. In place of the rotation detector, the electric motor 33 is controlled based on detection by a displacement sensor (not shown) that detects the position of the linear motion member 55 or a hydraulic pressure sensor that detects the hydraulic pressure of the master cylinder 2. It may be.

  Due to the rotation of the electric motor 33, the rotation member 57 of the ball screw mechanism 34 is rotationally driven through the rotation transmission mechanism 53, and the linear motion member 55 moves forward, thereby propelling the primary piston 72. At this time, the sub-piston 92 moves forward together with the primary piston 72 because the stepped portion 92 c is in contact with the front end portion of the primary piston 72. Thereby, the primary chamber 76 of the master cylinder 2 is pressurized by the input piston 93 (pressure receiving area C), the primary piston 72 (pressure receiving area A), and the sub piston 92 (pressure receiving area B). The brake hydraulic pressure generated in the master cylinder 2 is supplied to the hydraulic pressure control unit 5 through two lines, and further supplied to the wheel cylinder 4 of each wheel to generate a braking force.

  The hydraulic pressure in the primary chamber 76 of the master cylinder 2 is fed back as a reaction force to the brake pedal 22 via the input piston 93 (pressure receiving area C). By feeding back this reaction force, based on the ratio of the pressure receiving area C of the input piston 93 to the total pressure receiving area A, B and C of the primary piston 72, the sub piston 92 and the input piston 93, the electric booster 1 Basic input / output characteristics are determined. Further, by adjusting the relative positions of the input piston 93 and the primary piston 72 and the sub-piston 92, the reaction force against the input piston 93 (that is, the brake pedal 22) is adjusted by the spring force of the reaction force adjustment spring 100 to input / output. Properties can be controlled. At this time, by adjusting the position of the primary piston 72 forward with respect to the input piston 93, the degree of output with respect to the input increases, and by adjusting backward, the degree of output with respect to the input decreases. As a result, various brake controls such as boost control, brake assist control, inter-vehicle stability control, inter-vehicle control, and regenerative cooperative control can be executed.

  When the depression of the brake pedal 22 is released, the input piston 93, the primary piston 72, and the sub piston 92 are moved back to the retracted position, the brake hydraulic pressure of the master cylinder 2 is released, and the hydraulic pressure of the wheel cylinder 4 is released. The braking is released.

(During regenerative braking)
In the regenerative cooperative control, the generator is driven by the rotation of the wheel during braking to perform regenerative braking in which kinetic energy is converted into electric power and recovered, and the electric motor 33 is controlled by the controller 130 so that the master cylinder 2 is regenerated. By reducing the brake fluid pressure, a desired braking force corresponding to the operation amount of the brake pedal 22 is obtained. Specifically, during regenerative braking, the controller 130 reduces the advance amount of the primary piston 72 by the electric motor 33 by the amount by which the hydraulic pressure of the master cylinder 2 is reduced compared to during normal braking, that is, the target position of the primary piston 72. Is set to the reverse side (brake pedal 22 side) from the target position during normal braking to control the electric motor 33. At this time, since the distance between the rear end portion of the sub-piston 92 and the flange portion 93b is smaller than that during normal braking, the spring force of the reaction force adjusting spring 100 to the input piston 93 is larger than during normal braking, and the master The operating force of the brake pedal 22 is optimized by complementing the hydraulic reaction force that decreases as the cylinder 2 is depressurized.

(When boost is lost)
A case where the linear motion member 55 of the ball screw mechanism 34 cannot move forward from the retracted position due to a failure of the controller 130, the electric motor 33, the ball screw mechanism 34, or the like, that is, a case where the booster is lost will be described. As the operator operates the brake pedal 22, first, the input rod 21, the plunger rod 90 and the input piston 93 advance. In this case, the electric motor 33 cannot operate, the linear motion member 55 of the ball screw mechanism 34 does not advance, and the primary piston 72 and the sub piston 92 do not advance. At this time, the primary chamber 76 of the master cylinder 2 remains in communication with the reservoir 77 via the piston ports 72a and 95b until the stepped portion 93e of the input piston 93 comes into contact with the rear end portion of the sub-piston 92. Therefore, the master cylinder 2 does not generate brake fluid pressure. When the input member 31 continues to advance and the stepped portion 93 e of the input piston 93 comes into contact with the rear end portion of the sub-piston 92, the sub-piston 92 moves together with the input piston 93. As a result, the stepped portion 92c is separated from the front end portion of the primary piston 72, and the sub-piston 92 advances independently of the primary piston 72. When the sub piston 92 moves to a position where the piston port 95b of the sub piston 92 exceeds the piston seal 96 due to the advance of the input member 31, the primary chamber 76 is shut off from the reservoir 77, and the primary chamber 76 is connected to the input piston 93 and Pressurized by the sub-piston 92.

  Thus, even when the boost is lost, the brake fluid pressure can be generated by the operation of the brake pedal 22, that is, the pedaling force of the operator, and the braking function can be maintained. At this time, the input piston 93 and the sub-piston 92 pressurize the primary chamber 76 with the total area (B + C) of the pressure receiving area C of the input piston 93 and the pressure receiving area B of the sub-piston 92 to generate brake fluid pressure. Therefore, when the brake fluid pressure is generated only by the conventional input piston having a small pressure receiving area (for example, the pressure receiving area C in the present embodiment), or the brake is performed by using the entire cross-sectional area of the master cylinder by the input piston and the primary piston as the pressure receiving area. As compared with the case where the hydraulic pressure is generated, the brake hydraulic pressure can be generated with an appropriate pressure receiving area. For this reason, the operating force and stroke of the brake pedal 22 can be suitably performed.

  The pressure receiving areas A, B, and C of the primary piston 72, the sub piston 92, and the input piston 93 do not necessarily have to be A> B> C, and a desired boost can be obtained during normal braking. Moreover, what is necessary is just to set suitably so that the operating force and stroke of the brake pedal 22 can be optimized at the time of failure.

Next, the layout of each part of the electric booster 1 will be described mainly with reference to FIGS.
The housing 32 of the electric booster 1 has a motor holding part 120 to which the electric motor 33 is attached and a board holding part which is a control apparatus holding part to which a control board 131 (see FIG. 3) which is a main part of the controller 130 is attached. 121 and a transmission member accommodating portion 125 in which the ball screw mechanism 34 is accommodated are integrally formed. In addition, the board | substrate holding | maintenance part 121 can be integrally molded as the housing 32, or you may make it couple | bond together by fasteners, such as a volt | bolt, as a separate body. The control board 131 has a control circuit on which a power semiconductor element is mounted. This power semiconductor element constitutes an inverter circuit that generates AC power to be supplied to the electric motor 33. In addition, the control board 131 transmits and receives input signals and electric power from various sensors, an in-vehicle controller provided in the vehicle, etc. via a harness connected to a connector 132 (described later), and sends a control current to the electric motor 33. Supply.

  The motor holding portion 120 extends upward from the rear housing 36 along a plane perpendicular to the axis L of the master cylinder 2, and the electric motor 33 is coupled to the front portion (master cylinder 2 side) of the electric motor 33. A space for accommodating the rotation shaft and the pulley and belt of the rotation transmission mechanism 53 is formed.

  The transmission member accommodating portion 125 is formed at a position on the lower side of the motor holding portion 120 in the drawing, and a space for accommodating the ball screw mechanism 34 having the same axis as the axis L of the master cylinder 2 is formed.

  The substrate holding part 121 has an outer surface 121 a that extends from the rear housing 36 and the motor holding part 120 substantially parallel to the axis L and the vertical surface of the master cylinder 2, so that the motor holding part 120 and the transmission member containing part 125 It extends from the side surface to the position reaching the side of the front housing 35 in the protruding direction of the master cylinder 2. The substrate holding part 121 is formed as a substantially rectangular parallelepiped box having a space for accommodating the control substrate 131 (see FIG. 3) of the controller 130 therein. A gap C <b> 1 is formed between the outer surface 121 a on the opposite side of the inner bottom portion to which the control substrate 131 of the substrate holding part 121 is attached and the outer peripheral surface 41 of the electric motor 33. In the above embodiment, the substrate holder 121 is

  On the outer surface 121 a of the substrate holding part 121, a plurality of radiating fins 122 extending through the gap C <b> 1 toward the outer peripheral surface 41 side of the electric motor 33 is formed. The radiating fins 122 respectively extend along the vertical direction, and are formed in an arc shape along the cylindrical outer peripheral surface 41 so that the front end portions thereof do not contact the outer peripheral surface 41 of the electric motor 33.

  The opening of the substrate holding part 121 opposite to the bottom where the heat dissipating fins 122 are formed is closed with a lid 123 attached. A connector 132 for connecting a conductive wire for supplying electric power and control current to the control board 131 protrudes from the lid 123. In the above embodiment, the substrate holding part 121 is formed as a rectangular parallelepiped box, and the opening is closed by the lid 123. However, the present invention is not limited to this, and the substrate holding part is formed in a plate shape. Then, the control board 131 may be attached, and the control board 131 may be covered with a lid member of a rectangular parallelepiped box whose one surface is open.

  The positional relationship between the electric motor 33 and the substrate holding part 121 will be described in detail. In the present embodiment, the ball screw mechanism 34 and the input member 31 housed in the housing 32 are arranged coaxially with the axis L of the master cylinder 2. The electric motor 33 is arranged such that the center axis M (the center of the output shaft) of the electric motor 33 is along the axis L of the master cylinder at a position away from the axis L of the master cylinder 2. In the present embodiment, the electric motor 33 is positioned so that the central axis M of the electric motor 33 is parallel to the axis L of the master cylinder and behind the reservoir 77 attached to the upper part of the master cylinder 2. It is attached to the housing 32.

  Further, the electric motor 33 is held by the motor holding unit 120 so that the center axis M of the electric motor 33 is located away from the axis L of the master cylinder. The electric motor 33 is held by the motor holding unit 120 so that the outer peripheral surface 41 of the electric motor 33 is located away from the outer surface 121 a of the substrate holding unit 121. In the present embodiment, the electric motor 33 has a center axis M that is offset by a distance D1 on the axis L of the master cylinder 2 or on the opposite side of the substrate holder 121 from the axis L of the master cylinder 2 in the left-right direction of the vehicle. Are arranged. When the central axis M of the electric motor 33 is disposed on the axis L of the master cylinder 2, the distance D1 = 0. In particular, as shown in FIG. 4, in the present embodiment, the outer surface 121 a of the substrate holding part 121 is formed along the vertical direction. However, the present invention is not limited thereto, and the outer surface 121 a is inclined with respect to the vertical direction. Thus, the substrate holding part 121 may be formed.

  Thereby, the electric motor 33 and the controller 130 can be efficiently arranged, the radial dimension around the axis L of the master cylinder 2 can be reduced, and the electric booster 1 can be downsized. In addition, a gap C1 is provided between the board holding part 121 to which the control board 131 on which the power semiconductor is mounted is attached and the outer peripheral surface 41 of the electric motor 33, and furthermore, the radiation fins 122 are provided in the board holding part 121. In addition to suppressing heat exchange between the control board 131 and the electric motor 33 that generate a large amount of heat, the gap C serves as a heat dissipation path, and the cooling efficiency can be increased in combination with the heat dissipation effect of the heat dissipation fins 122.

  The electric booster according to the present invention is not limited to the above-described type, and can be applied to other types as long as the electric motor is used as a drive source to propel the piston of the master cylinder. By adopting the layout of the master cylinder, the electric motor, and the controller as described above, the above-described effects can be achieved.

  In the above embodiment, the housing coupled to the master cylinder, the electric motor disposed in the housing, and the housing accommodated in the housing transmit the output of the electric motor to propel the piston of the master cylinder. In the electric booster including a transmission mechanism and a control board for controlling the operation of the electric motor, the housing has a central axis of the electric cylinder at a position away from the axis of the master cylinder. A motor holding part for arranging and holding the electric motor along the axis, and a control board arranged and held so as to face the axis of the master cylinder and the side of the central axis of the electric motor. A control board holding unit, and the electric motor has a central axis of the electric motor from the control board holding unit to the master chassis. Becomes position spaced above the axis of Sunda, the has a structure in which the outer peripheral surface of the electric motor is held in the motor holding portion so that the position away from the control substrate holder. As a result, it is possible to satisfy both the size reduction and heat dissipation requirements of the electric booster.

  In the above embodiment, a semiconductor element that generates AC power to be supplied to the electric motor is mounted on the control board, and the control board is disposed so that the semiconductor element faces the control board holding portion. It has a structure. For this reason, the heat which generate | occur | produces in a control board can be efficiently transmitted to a control board holding | maintenance part, and the heat dissipation of an electric booster can be improved.

  In the above embodiment, the control device holding part is provided with heat radiation fins extending toward the outer peripheral surface of the electric motor. For this reason, the heat dissipation of an electric booster can be improved.

  DESCRIPTION OF SYMBOLS 1 ... Electric booster, 2 ... Master cylinder, 32 ... Housing, 33 ... Electric motor, 34 ... Ball screw mechanism (transmission mechanism), 72 ... Primary piston (piston), 131 ... Control board (control device), 120 ... Motor Holding unit, 121 ... Substrate holding unit (control device holding unit), C1 ... Clearance, L ... Axis, M ... Center axis

Claims (3)

A housing coupled to the master cylinder; an electric motor disposed in the housing; a transmission mechanism housed in the housing for transmitting the output of the electric motor to propel the piston of the master cylinder; In an electric booster comprising a control board for controlling the operation of the motor,
In the housing, a motor holding portion that holds and holds the electric motor so that a central axis of the electric motor is along the axis of the master cylinder at a position away from the axis of the master cylinder;
A control board holding portion for arranging and holding the control board so as to extend facing the side of the axis of the master cylinder and the central axis of the electric motor;
The electric motor has a position in which the central axis of the electric motor is separated from the control board holding part more than the axis of the master cylinder, and the outer peripheral surface of the electric motor is located away from the control board holding part. The electric booster is held by the motor holding part. A semiconductor element that generates AC power supplied to the electric motor is mounted on the control board,
The electric booster according to claim 1, wherein the control board is disposed so that the semiconductor element faces the control board holding portion.   The electric booster according to claim 1, wherein the control device holding portion is provided with a heat radiation fin extending toward an outer peripheral surface of the electric motor.

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