CN115709707A

CN115709707A - Electromechanical brake booster

Info

Publication number: CN115709707A
Application number: CN202210896323.8A
Authority: CN
Inventors: 木村和树; 末永直也
Original assignee: Nikki Co Ltd
Current assignee: Nikki Co Ltd
Priority date: 2021-08-23
Filing date: 2022-07-28
Publication date: 2023-02-24
Also published as: JP2023030664A

Abstract

The invention provides an electromechanical brake booster. In an electromechanical brake booster, when a Brake Pedal (BP) is depressed, a control lever (40) which moves linearly in the axial direction is operated to drive a motor unit (60), a rotational/linear motion conversion unit (80) converts rotational motion into linear motion of a screw member (81), and a piston (130) of a master cylinder (120) filled with brake fluid for hydraulic braking is moved by the linear motion of the screw member (81), thereby eliminating the problem of defective contact function with the piston (130) of the master cylinder (120) due to cutting of a screw portion of the screw member (81) or wear of a contact surface. A push plate (44) is interposed between the front end surface (81 a) of the screw member and the connecting surface (130 a) of the piston, and the push plate is in plate-like contact with the front end surface of the screw member and the connecting surface of the piston and is formed of a rigid material.

Description

Electromechanical brake booster

Technical area

The present invention relates to an electromechanical brake booster for amplifying the force of a brake pedal in a motor vehicle.

Background

Conventionally, a brake booster device for amplifying a stepping force when a brake pedal is depressed in order to assist a braking operation of an automobile is known, and a vacuum brake booster device using a negative pressure of an engine (engine) is generally used as an invention described in japanese patent application laid-open No. 54-90459 (patent document 1), for example.

However, in recent years, the dynamics of carbon neutralization in countries around the world have been actively pursued, and in order to achieve the goal of getting rid of fossil fuels, the shift to automobiles without an engine as a power source, such as electric automobiles and fuel cell automobiles, is an important issue in the automotive industry in the future.

As described above, one of the differences between a conventional vehicle mounted with an engine and a vehicle not mounted with an engine, such as an electric vehicle, is that since the vehicle does not have an engine, negative pressure (intake pipe negative pressure) of the engine used in a conventional system is not generated, and thus, there is a problem that each component using the negative pressure cannot be used.

Therefore, there is a need for a brake booster capable of obtaining a high braking force that can be used in automatic braking in place of a vacuum brake booster, and for example, an electromechanical brake booster having a motor as a power source is known as an invention described in japanese patent application laid-open No. 2018-199448 (patent document 2) and japanese re-table No. 2018/097278 (patent document 3).

According to these conventional electromechanical brake servo devices, even in a vehicle not having an engine, the stepping force when the brake pedal is depressed can be amplified by using a motor driven by electric power.

Fig. 5 and 6 show an example of a conventional electromechanical brake servo unit, which is an electromechanical brake servo unit 2 including: a control lever 40 having a base end to which a brake pedal BP is coupled and which linearly moves in an axial direction in accordance with an operation of the brake pedal BP, a sensor unit 50 including a position sensor for detecting a displacement of the control lever 40, a motor unit 60 having a stator 61, a rotor 62 and a rotary shaft 63 which operate in accordance with the displacement of the control lever 40, a control unit 70 for driving the motor unit 60 by using information obtained from the sensor unit 50, a rotational/linear motion converter 80 including a cylindrical screw member 81 and a rotary member 82, the screw member 81 having an external thread on an outer periphery thereof, the rotary member 82 having an internal thread portion on an inner periphery thereof which is screwed with the external thread portion of the screw member 81 and being linked with the motor unit 60, the rotational/linear motion converter 80 converting a rotational motion of the rotary member 82 rotated by the motor unit 60 into a linear motion of the screw member 81, and a master cylinder member 120 connected to a front end surface of the screw member 81, having a piston 130 which operates by the linear motion of the screw member 81, and being filled with brake fluid for hydraulic braking; when the brake pedal BP is depressed, the operation of the control lever 40 that moves linearly in the axial direction is detected by the sensor unit 50, and the control lever 40 drives the motor unit 60, and the rotational motion is converted into the linear motion of the screw member 81 by the rotational-linear motion conversion unit 80, and the piston 130 of the master cylinder 120 filled with the brake fluid for hydraulic braking is moved by the linear motion of the screw member 81, thereby generating the electromechanical brake assist force.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. Sho 54-90459

Patent document 2: japanese patent laid-open publication No. 2018-199448

Patent document 3: JP 2018/097278A

Disclosure of Invention

Problems to be solved by the invention

However, in the conventional electromechanical brake servo unit 2 shown in fig. 5 and 6, the screw member 81 contacts the piston 130 of the master cylinder 120 with the end surface 81a of the screw portion of the screw member 81 contacting the end surface 130a of the piston 130.

Therefore, there is a concern that the contact function with the piston 130 of the master cylinder 120 may be poor due to cutting of the threaded portion of the screw member 81 or abrasion of the contact surface.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an electromechanical brake booster in which a contact surface between a screw member 81 and a piston 130 of a master cylinder 120 is increased, and a problem that a contact function with the piston 130 of the master cylinder 120 is defective due to cutting of a screw portion of the screw member 81 or abrasion of the contact surface is solved.

Means for solving the problems

In order to solve the above problems, an electromechanical brake servo unit is provided with: a control lever having a proximal end connected to a brake pedal and linearly moving in an axial direction in accordance with an operation of the brake pedal, a sensor unit including a position sensor for detecting a displacement of the control lever, a motor unit operated in accordance with the displacement of the control lever, the control unit driving the motor unit by information obtained from the sensor unit, a rotational/linear motion conversion unit including a cylindrical screw member having a screw thread on an outer circumference thereof and a screw thread portion on an inner circumference thereof, the screw member being interlocked with the motor unit, the rotational/linear motion conversion unit converting a rotational motion of the rotational member rotated by the motor unit into a linear motion of the screw member, and a master cylinder connected to a distal end surface of the screw member, having a piston operated by the linear motion of the screw member, and filled with a brake fluid for hydraulic braking; the electromechanical brake booster is characterized in that a push plate is inserted between the front end face of the screw rod component and the connecting face of the piston of the main cylinder, and the push plate is in contact with the front end face of the screw rod component and the connecting face of the piston, is in a plate shape, and is made of rigid materials.

According to the present invention, since the front end surface of the screw member and the connecting surface of the piston are pressure receiving surfaces having rigidity over the entire surfaces thereof, it is possible to prevent a failure in the contact function with the piston of the master cylinder due to cutting of the screw portion of the screw member or abrasion of the contact surface.

In the present invention, the push plate has a circular disk shape with the screw member as an axis, the push plate has an inner diameter smaller than or equal to an inner diameter of the hollow portion of the screw member, and the push plate has an outer diameter larger than or equal to an outer diameter of the piston, and in this case, the entire areas of the front end surface of the screw member and the connecting surface of the piston of the master cylinder can be set as pressure receiving surfaces, and therefore, a functional failure in contact with the piston of the master cylinder due to cutting of the screw portion of the screw member or wear of the contact surface due to use can be reliably prevented.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, since the connecting surface of the screw member and the connecting surface of the piston are pressure receiving surfaces having rigidity over the entire surfaces thereof, it is possible to prevent a failure in the contact function with the piston of the master cylinder due to cutting of the screw portion of the screw member or abrasion of the contact surface, and to reliably operate the screw member and the piston of the master cylinder.

Drawings

FIG. 1 is a cross-sectional view showing a preferred embodiment of the electromechanical brake assist device of the present invention.

Fig. 2 is a cross-sectional view at a different angle of the embodiment shown in fig. 1.

Fig. 3 is a partially enlarged sectional view of a main portion of the embodiment shown in fig. 1.

Fig. 4A and 4B are partial sectional views with enlarged main portions of different embodiments, fig. 4A being a view in a case where an outer diameter of a push plate is larger than an outer diameter of a piston, and fig. 4B being a view in a case where the outer diameter of the push plate is smaller than the outer diameter of the piston.

Fig. 5 is a sectional view showing a conventional example.

Fig. 6 is a partially enlarged sectional view of a main portion of the conventional example shown in fig. 5.

Description of the reference numerals

1. 2: electromechanical brake booster, 10: a housing, 11: outer shell, 12: bottom plate, 13: set screw, 14: fixing member, 16: mounting hole, 17: mounting hole, 18: mounting hole, 20: input lever, 21: connection hole, 22: spring holding hole, 23: brake attachment, 30: urging member, 31: coil spring, 32: holder, 33: bearing surface, 35: conical spring, 36: fixing part, 40: control lever, 41: ball stud, 42: magnet, 43: flange, 44: push plate, 45: step portion, 46: coil spring, 47: tip end portion, 50: sensor unit, 51: sensor base, 52: position sensor, 60: motor section, 61: stator, 62: rotor, 63: rotation axis, 64: bearing, 65: bearing, 66: detection gear, 67: detection gear, 68: motor case, 70: control unit, 71: control board, 72: revolution number sensor, 73: cable, 74: cable, 80: rotation/translation conversion unit, 81: screw member, 81a: front end face, 82: rotating member, 83: connecting member, 90: support, 91: through-hole, 92: through hole, 93: flange bushing, 100: strut, 101: small diameter portion, 102: large diameter portion, 103: tip portion, 104: nut, 110: return spring, 120: master cylinder, 121: cylinder bore, 122: first output port, 123: second output port, 124: mounting hole, 125: bolt, 126: nut, 127: main chamber, 128: sub-chamber, 130: piston, 130a: connection surface of piston, 131: partition wall, 132: recess, 133: elastomer, 134: coil spring, 135: telescoping member, 136: holding guide, 137: stopper, 138: holding rod, 139: shoulder, 140: auxiliary piston, 141: partition wall, 142: recesses, 143, 144: coil spring, 145: telescoping member, 146: holding guide, 147: stopper, 148: holding rod, 149: shoulder, 151: sealing member, 152: sealing member, 161: sealing member, 162: sealing member, BP: brake pedal, d1: inner diameter of push plate, d2: outer diameter of push plate, d3: inner diameter of hollow portion of screw member, d4: the outer diameter of the piston.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the same reference numerals are given to the same components as those of the conventional electromechanical brake servo unit 2.

Fig. 1 to 3 are views showing a preferred embodiment of the electromechanical brake assist device 1 of the present invention, and the electromechanical brake assist device 1 includes a housing 10, an input lever 20, an urging member 30, a control lever 40, a sensor unit 50, a motor unit 60, a control unit 70, a rotational/linear motion converting unit 80, a bracket 90, a strut 100, a return spring 110, and a master cylinder 120.

The housing 10 has a cylindrical outer shell 11 and an annular bottom plate 12. In fig. 1, reference numeral 13 denotes a fixing screw for fixing the housing 11 and the bottom plate 12, and reference numeral 14 denotes a fixing member for fixing the case 10 to a vehicle body of an automobile.

The input rod 20 is a rod-shaped overall, is movable in the axial direction and is swingable within a predetermined angular range, and has a connection hole 21 and a spring holding hole 22 continuously formed in an end surface thereof on one end side (control rod 40 side), the connection hole 21 extending in the axial direction of the input rod 20, the spring holding hole 22 extending in the axial direction and having a smaller diameter than the connection hole 21, the input rod 20 having a brake pedal link 23 attached to the other end side, the brake pedal link 23 being connected to the brake pedal BP so as to be rotatable in the circumferential direction.

The biasing member 30 includes a coil spring 31 that generates a reaction force and a retainer 32, and the retainer 32 is formed in a conical shape as a whole and has a mortar-shaped receiving surface 33 on the inner side.

The control lever 40 is a rod-shaped overall and movable in the axial direction, and has a ball stud 41 fixed to one end side (input lever 20 side) in a state where a magnet 42 for position detection is externally fitted with a flange 43 so as not to come off, and a step portion 45 for engaging with a push plate 44 and a small-diameter tip portion 47 for externally fitting a coil spring 46 formed on the other end side.

The sensor unit 50 includes a sensor base 51 and a position sensor 52, and the displacement amount of the magnet 42 detected by the position sensor 52 is output as a signal via the sensor base 51.

The motor unit 60 includes a stator 61, a rotor 62, a rotary shaft 63 that rotates in synchronization with the rotor 62, and two

bearings

64 and 65 that support the rotary shaft 63 so as to be rotatable in the circumferential direction. Further,

reference numerals

66 and 67 are detection gears for detecting the number of rotations, and reference numeral 68 in the drawing is a motor housing that is installed to stand from the base plate 12 and covers the motor section 60.

The control unit 70 is a control board 71 having a function of a motor driver for controlling electric power supplied from the outside via a power supply cable (not shown) and driving the motor unit 60, and the control board 71 is connected to the position sensor 52 and the rotational speed sensor 72 via

cables

73 and 74, and drives the motor unit 60 by signals from the sensors.

In the present embodiment, two sets of the rotation number sensor 72 and the

corresponding detection gears

66 and 67 are provided, and for example, the rotation number sensors having different performance are used, whereby the motor control can be performed at high accuracy and high speed at the same time.

The rotational/linear motion converter 80 is a mechanism for converting the rotational motion of the motor 60 into a linear motion, and is constituted by a feed screw mechanism including a cylindrical screw member 81, a nut-shaped rotating member 82, and a cylindrical coupling member 83, the screw member 81 having a thread bar formed on the outer periphery thereof, the rotating member 82 having a thread groove formed on the inner periphery thereof and being screwed into the screw member 81, and the coupling member 83 coupling the rotating member 82 to the rotary shaft 63 of the motor 60. In the present embodiment, the rotating member 82 and the coupling member 83 are formed separately and integrally coupled, but may be integrally formed.

The holder 90 has a substantially regular triangle shape in plan view, and through

holes

91 and 92 are formed at the center and near each vertex. In said centrally located through hole 91The above-mentionedThe screw members 81 are fixed, and the brackets 90 are attached to the three support columns 100 via flange bushes 93 respectively attached to the through holes 92 near the respective apexes, whereby the three support columns are configured to be axially movable without being axially rotatable, and to be restricted from axial movementThe above-mentionedThe shaft of the screw member 81 rotates and moves in the axial direction in a linked manner.

The 3 support columns 100 are arranged between the housing 11 and the bottom plate 12, and a small diameter portion 101 formed near one end is inserted into a mounting hole 16 formed in the bottom plate 12, and a large diameter portion 102 formed adjacent to the small diameter portion 101 is brought into contact with the bottom plate 12 to perform positioning, and a nut 104 is attached to a tip end portion 103 of the support column protruding from a mounting hole 17 formed in the housing 11 to perform fixing.

The return springs 110 are provided to bias the holder 90 to return to an original position after the movement, and are externally mounted to 3 support columns 100 for reinforcement provided between the housing 11 and the bottom plate 12, respectively, and have one end in contact with the bottom plate 12 and the other end in contact with the flange bushing 93.

The master Cylinder 120 includes a Cylinder bore (Cylinder bore) 121, a piston 130, and a sub piston 140, the Cylinder bore 121 is a bottomed Cylinder having a first output port 122 and a second output port 123 formed in a side surface thereof, the piston 130 is disposed in the Cylinder bore 121, the sub piston 140 is disposed in the Cylinder bore 121 on a bottom surface side of the piston 130, the master Cylinder 120 is disposed such that an opening of the Cylinder bore 121 faces an opening below the housing 10 and is closed, and the master Cylinder 120 is fixed by a bolt 125 and a nut 126 inserted in a state in which the mounting hole 124 of the Cylinder bore 121 and the mounting hole 18 of the base plate 12 communicate with each other.

Both end portions of the piston 130 are formed in a cup shape and have an H-shaped cross section divided by a partition wall 131. The elastic body 133 is fitted into a recess 132 formed on the base end side (the lever 40 side) of the partition wall 131, and the tip end portion 47 of the lever 40 is in contact with the elastic body 133.

In the present embodiment, in particular, a push plate 44 is interposed between the front end surface 81a of the screw member 81 and the connection surface 130a (end surface) of the piston 130 of the master cylinder 120, and the push plate 44 is formed of a rigid material such as a metal, which is plate-shaped, and which contacts the front end surface 81a of the screw member 81 and the connection surface 130a of the piston 130.

The push plate 44 is a circular disk shape having the screw member 81 as an axis, and has an inner diameter d1 equal to or smaller than an inner diameter d3 of the hollow portion of the screw member 81 and an outer diameter d2 equal to or larger than an outer diameter d4 of the piston 130, so that the entire region of the front end surface 81a of the screw member 81 and the connecting surface 130a of the piston 130 of the master cylinder 120 can be a pressure receiving surface.

To describe in more detail, as shown in fig. 3, in the present embodiment, the inner diameter d1 of the push plate 44 is smaller than the inner diameter d3 of the hollow portion of the screw member 81, and the outer diameter d2 is formed to be equal to the outer diameter d4 of the piston 130, but the outer diameter d5 of the push plate 44 may be made larger than the outer diameter d4 of the piston 130 as in the embodiment shown in fig. 4A, or the outer diameter d6 of the push plate 44 may be made smaller than the outer diameter d4 of the piston 130 as in the embodiment shown in fig. 4B.

Even in any case where the outer diameter of the push plate 44 is smaller, equal, or larger than the outer diameter of the piston 130, the screw member 81 and the piston 130 do not directly contact each other as in the conventional example, and a force for moving the screw member 81 in the axial direction can be applied to the piston 130 by a pressure receiving surface larger than the direct contact.

The two end portions of the sub-piston 140 are formed in a cup shape and have an H-shaped cross section divided by a partition wall 141. A recess 142 is formed on the base end side (the piston 130 side) of the partition wall 141, and a holding rod 148 described later is in contact with the recess 142.

In the cylinder bore 121 of the master cylinder 120, a master chamber 127 is formed between the piston 130 and the sub-piston 140, and a sub-chamber 128 is formed between the bottom of the cylinder bore 121 and the sub-piston 140. Further, the cylinder hole 121 including the master chamber 127 and the sub-chamber 128 is filled with brake fluid as a working fluid, which is supplied from a reservoir not shown.

At this time, the brake fluid does not leak out of the predetermined region by the

seal members

151 and 152 and the

seal members

161 and 162, the

seal members

151 and 152 are attached between the outer periphery of the piston 130 and the inner periphery of the cylinder hole 121, and the

seal members

161 and 162 are attached between the outer periphery of the sub piston 140 and the inner periphery of the cylinder hole 121.

The master chamber 127 and the sub-chamber 128 of the master cylinder 120 are connected to the first output port 122 and the second output port 123 formed in the side surface of the cylinder hole 121, respectively, and the brake fluid pressure of the brake fluid output from the other system is supplied from each output port to the brake (not shown) of each wheel to generate a braking force.

A coil spring 134 is interposed between the piston 130 and the sub-piston 140, and the coil spring 134 biases the piston 130 and the sub-piston 140 in a direction of separating from each other. An extensible member 135 is disposed inside the coil spring 134, and the extensible member 135 includes a holding guide 136 and a holding rod 138 for holding the piston 130 and the sub-piston 140 at a predetermined interval.

The holding guide 136 is cylindrical, and has a stopper 137 formed at the front end thereof so as to protrude inward. The holding rod 138 has a rod shape, and a shoulder 139 protruding radially outward is formed at the base end. Then, by inserting the holding rod 138 into the holding guide 136, the holding guide 136 and the holding rod 138 can be relatively moved in the axial direction, and the telescopic member 135 is extended to a predetermined length at a point of time when the stopper 137 of the holding guide 136 interferes with the shoulder 139 of the holding rod 138.

A coil spring 144 is interposed between the sub piston 140 and the bottom of the cylinder bore 121, and the coil spring 144 biases the sub piston 140 and the bottom of the cylinder bore 121 in a direction away from each other. An expansion member 145 is disposed inside the coil spring 144, and the expansion member 145 includes a holding guide 146 and a holding rod 148 for holding the sub-piston 140 and the bottom of the cylinder bore 121 at a predetermined distance.

The holding guide 146 has a cylindrical shape, and a stopper 147 protruding inward is formed at the front end. The holding rod 148 has a hollow rod shape, and a shoulder portion 149 protruding radially outward is formed at the base end. Then, by inserting the holding rod 148 into the holding guide 146, both can relatively move in the axial direction, and the extensible member 145 is extended to a predetermined length at a point of time when the stopper 147 of the holding guide 146 interferes with the shoulder portion 149 of the holding rod 148.

The operation of the electromechanical brake servo unit 1 of the present embodiment will be described below.

When the driver depresses the brake pedal BP in a state where the electromechanical brake booster 1 is mounted in the vehicle, the input rod 20 connected to the brake pedal BP moves in the axial direction, and the control rod 40 performs a linear motion in synchronization with the input rod 20.

At this time, since the control rod 40 and the screw member 81 are not synchronized and can move in the axial direction, only the control rod 40 moves without changing the position of the screw member 81.

The control rod 40 advances the piston 130 and the sub-piston 140 against the biasing forces of the coil springs 46, 134, and 144.

When the control lever 40 moves, the control unit 70 controls the supply of electric power and an operation signal to the motor unit 60 by a signal transmitted from the position sensor 52 that detects the displacement to the control unit 70, and the motor unit 60 operates and rotates.

Further, a rotation number sensor 72 for detecting the rotation number of the motor by detecting the rotation number of the detection gears 66 and 67 attached to the rotary shaft 63 is provided, and when the control unit 70 controls the supply of electric power and the operation signal to the motor unit 60, a signal transmitted from the rotation number sensor 72 to the control unit 70 via the cable 74 can be used.

When the motor unit 60 rotates, the rotary member 82 rotates in synchronization with the rotary shaft 63 via the coupling member 83, but since the screw member 81 is restricted in shaft rotation by the holder 90, the rotary motion of the rotary member 82 during screw engagement is converted into a linear motion, and the piston 130 and the sub-piston 140 on the axis move in the forward direction.

At this time, the holder 90 also compresses the return spring 110 in synchronization with the screw member 81 and moves in a direction to advance the piston 130 and the sub-piston 140 on the axis, but slides while being guided by the column 100 via the flange bushing 93, and therefore can operate smoothly.

Then, the screw member 81 advances the piston 130 and the sub-piston 140 via the push plate 44 against the urging force of the coil springs 134, 144.

In this way, the depression force when the driver depresses the brake pedal BP is directly applied to the piston 130 and the sub-piston 140 of the master cylinder 120 via the input rod 20 and the control rod 40, and the pressing force for converting the rotational operation of the motor unit 60 into the linear operation of the screw member 81 is applied to the piston 130 and the sub-piston 140 of the master cylinder via the screw member 81.

In this case, in the present embodiment, a push plate 44 is interposed between the front end surface 81a of the screw member 81 and the connection surface 130a of the piston 130 of the master cylinder 120, and the push plate 44 is formed of a rigid material such as metal, for example, in a plate shape, and is in contact with the front end surface 81a of the screw member 81 and the connection surface 130a of the piston 130.

Therefore, the contact surface between the screw member 81 and the piston 130 of the master cylinder 120 is increased, and not only the driving force by the screw member 81 is reliably transmitted to the piston 130 of the master cylinder 120, but also the problem of poor contact function with the piston 130 of the master cylinder 120 due to cutting of the thread portion of the screw member 81 or abrasion of the contact surface can be eliminated.

Claims

1. An electromechanical brake booster comprising:

a control rod having a base end connected to a brake pedal and linearly moving in an axial direction in accordance with an operation of the brake pedal,

a sensor section including a position sensor that detects a displacement of the control rod,

a motor part operated according to the displacement of the control rod,

a control unit for driving the motor unit by using information obtained from the sensor unit,

a rotational/linear motion conversion unit including a cylindrical screw member having a screw thread on an outer periphery thereof and a rotary member having a screw thread on an inner peripheral surface thereof, the rotary member being engaged with the motor unit and being screwed with the screw thread of the screw member, the rotational/linear motion conversion unit converting a rotational motion of the rotary member rotated by the motor unit into a linear motion of the screw member, and

a master cylinder connected to a front end surface of the screw member, having a piston operated by linear motion of the screw member, and filled with a brake fluid for hydraulic braking;

the electromechanical brake booster is characterized in that,

a push plate is inserted between the front end surface of the screw member and the connecting surface of the piston of the master cylinder, and the push plate is in plate-like contact with the front end surface of the screw member and the connecting surface of the piston and is formed of a rigid material.

2. An electromechanical brake boosting device according to claim 1,

the push plate is in a ring disc shape with the screw rod component as an axis, the inner diameter of the push plate is smaller than or equal to that of the hollow part of the screw rod component, and the outer diameter of the push plate is larger than or equal to that of the piston.