JP2006200752A - Electric brake - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent wear due to friction between members in a force transmission mechanism in an electric drum brake operated by transmitting driving force of a motor to a lever turned to press a brake shoe against a drum by the force transmission mechanism. <P>SOLUTION: The force transmission mechanism has a structure for transmitting driving force of a shoe extension actuator 250 using the motor as a driving source to the lever 230 through a flexible main brake cable 240. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electric brake using a motor as a drive source.

The electric brake generally includes (a) a rotating body that has a friction surface and rotates together with the wheel, (b) a friction material that is pressed against the friction surface to suppress the rotation of the rotating body, and (c) a brake pedal, etc. A motor driven by electric power based on the operation of the brake operation member; (d) a rotation member that presses the friction material against the friction surface by rotation; and (e) a driving force of the motor is transmitted to the rotation member. And a force transmission mechanism.
A conventional example of this electric brake is described in Patent Document 1. In this electric brake, the force transmission mechanism has a structure for transmitting the driving force of the motor to a lever as a rotating member via a rigid shaft that is driven along a straight line by the driving force of the motor; It had been.
European Patent Application Publication No. EP 0594233A1

In this conventional electric brake, each point on the shaft moves along a single line while each point on the shaft moves along a single circle when driven by a motor. Thus, the movement trajectories are different between the points on the shaft and the points on the lever. Therefore, in this conventional electric brake, when driven by a motor, slippage or friction occurs between the shaft and the lever in a direction crossing the moving direction of the shaft, so that the contact portion between the shaft and the lever is reduced. There was a problem of being easily worn.
The present invention has been made against the background of the above circumstances, and an object thereof is to provide an electric brake capable of suppressing wear between members in a force transmission mechanism.

Means and effects for solving the problem

  The problem is that an electric brake is attached to (a) a rotating body having a friction surface and rotating with a wheel, (b) a non-rotating body, and (c) the non-rotating body so as to be relatively movable, A friction material pressed against the friction surface to suppress the rotation of the rotating body, (d) a motor driven by electric power based on the operation of the brake operation member, and (e) rotating around the rotation axis at one end. An electric brake including a rotation member that can be provided and presses the friction material against the friction surface based on the rotation, and (f) a force transmission mechanism that transmits the driving force of the motor to the rotation member. The motor is fixed to the non-rotating body to which the friction material is attached so as to be relatively movable, and the force transmission mechanism is flexible with the driving force of the motor as the rotating member. Having a structure for transmitting via a relay member, and said relay One end of the material is coaxially fixed to the output member of the motion conversion mechanism that converts the rotational motion of the rotating shaft of the motor into the linear motion of the output member, and the other end of the relay member is The problem is solved by being connected to the other end opposite to the one end.

In this brake, the driving force of the motor is transmitted to the rotating member via a flexible relay member. The motor is fixed to the non-rotating body, and one end of the relay member is fixed coaxially to the output member of the motion conversion mechanism that converts the rotational motion of the rotation shaft of the motor into the linear motion of the output member. The other end of the relay member is connected to the other end of the member. Wear caused by the difference between the linear movement trajectory at one end of the relay member and the arc-shaped movement trajectory at the other end of the rotating member is suppressed by bending of the relay member. Therefore, according to this brake, when the motor is driven, slippage, that is, friction does not occur at the contact portion between the relay member and the rotating member, so that wear of the contact portion of the two members in the force transmission mechanism is suppressed. Is done.
In this brake, the “flexible relay member” is not limited as long as it is more easily deformable than a rigid relay member, and is composed of a flexible wire, a flexible rod, or a flexible leaf, which will be described later. It can consist of a spring.
The motor is fixed to a non-rotating body to which the friction material is attached so as to be relatively movable. The non-rotating body is one of the components of this brake.

Patentable invention

  In the following, the invention that is claimed to be claimable in the present application (hereinafter referred to as “claimable invention”. The claimable invention is at least the “present invention” to the invention described in the claims. Some aspects of the present invention, including subordinate concept inventions of the present invention, superordinate concepts of the present invention, or inventions of different concepts) will be illustrated and described. As with the claims, each aspect is divided into sections, each section is numbered, and is described in a form that cites the numbers of other sections as necessary. This is merely for the purpose of facilitating understanding of the claimable invention, and is not intended to limit the set of components constituting the claimable invention to those described in the following sections. In other words, the claimable invention should be construed in consideration of the description accompanying each section, the description of the embodiments, etc., and as long as the interpretation is followed, another aspect is added to the form of each section. In addition, an aspect in which constituent elements are deleted from the aspect of each item can be an aspect of the claimable invention.

(1) a rotating body that has a friction surface and rotates with the wheel;
A non-rotating body,
A friction material attached to the non-rotating body so as to be relatively movable, and pressed against the friction surface to suppress the rotation of the rotating body;
A motor driven by electric power based on the operation of the brake operation member;
A rotation member provided at one end so as to be rotatable around a rotation axis, and based on the rotation, a rotation member that presses the friction material against the friction surface;
An electric brake including a force transmission mechanism that transmits the driving force of the motor to the rotating member.
The motor is fixed to the non-rotating body to which the friction material is attached so as to be relatively movable, and the force transmission mechanism uses the driving force of the motor as the rotating member and has a flexible relay member. And one end of the relay member is coaxially fixed to the output member of the motion conversion mechanism that converts the rotational motion of the rotating shaft of the motor into the linear motion of the output member, The other end portion of the relay member is connected to the other end portion on the opposite side to the one end portion of the rotating member (Claim 1).
(2) The other end of the relay member extends to the other end of the rotating member in a direction substantially orthogonal to the direction of the force applied to the one end of the relay member by the motion conversion mechanism. The rotation member is connected by contact with a plane parallel to the plane, and the force transmission mechanism includes a contact portion between the other end portion of the relay member and the other end portion of the rotation member. Wear caused by the difference between the linear movement trajectory of the one end of the relay member and the arc-shaped movement trajectory of the other end of the rotating member is suppressed by the deflection of the relay member (1 The electric brake according to claim 2 (claim 2).
(3) The two relay members are directly connected to the rotating member, and the force transmission mechanism transmits the driving force of the motor to the rotating member via one relay member. A force applying mechanism for applying a tensile force of a second brake operation member different from the first brake operation member as the brake operation member to the rotating member via the other relay member. Including the electric brake according to (1) or (2) (claim 3).
According to this brake, two types of brake operations can be performed by the same rotating member. Therefore, the brake device can be reduced in size, weight, and cost compared with the case where a rotating member is provided for each type of brake operation. It becomes easy.
In this brake, regardless of the type of brake operation, if a tensile force is applied to the rotating member, the rotating member is rotated in the same direction. Therefore, when the relay member that applies the tensile force to the rotating member does not have flexibility, even if an attempt is made to apply the tensile force to the rotating member via the relay member for a certain brake operation, the application is not performed. It will be obstructed by the other relay member. On the other hand, in this brake, any relay member has flexibility, and if it is going to give tensile force to a rotation member via one relay member for one brake operation, it will be. Accordingly, the other relay member bends accordingly. Therefore, according to this brake, the use of the flexibility of the relay member prevents one brake operation from being hindered by the relay member for the other brake operation without a complicated mechanism. .
(4) a rotating body having a friction surface and rotating together with the wheel;
A motor driven by electric power based on the operation of the first brake operation member;
A rotation member provided at one end so as to be rotatable around a rotation axis, and based on the rotation, a rotation member that presses the friction material against the friction surface;
The flexible member includes two flexible relay members that are directly connected to the rotating member, and one of the two relay members has a second brake operation separate from the first brake operation member. A tensile force based on the operation force of the member is applied, the driving force of the motor is applied to the other of the two relay members, and one end portion of the other relay member rotates the rotation shaft of the motor. The other end of the rotating member is opposite to the one end of the rotating member, and the other end of the other relay member is coaxially fixed to the output member of the motion converting mechanism that converts the motion into a linear motion of the output member. An electrically driven brake characterized in that it is connected to the electric brake (claim 4).
(5) The other end of the other relay member is in a direction substantially orthogonal to the direction of the force applied to the other end of the rotating member by the motion conversion mechanism. The extended plane and the rotating member are connected by contact with a plane parallel to the plane, and the force transmission mechanism is between the other end of the other relay member and the other end of the rotating member. Wear caused by the difference between the linear movement locus of the one end of the other relay member and the arcuate movement locus of the other end of the rotating member of the contact portion of the other relay member. The electric brake according to (4), wherein the electric brake has a structure that is suppressed by bending (claim 5).
(6) The electric brake according to (4) or (5), wherein the electric brake includes a non-rotating body that holds the friction material so as to be relatively movable, and the motor is fixed to the non-rotating body. Brake (Claim 6).
(7) The first brake operation member is a member operated by a driver to decelerate and stop the vehicle, and the second brake operation member is operated by the driver to keep the vehicle in a stopped state. The electric brake according to any one of (3) to (6), wherein the electric brake is a member.
The main brake operation that is normally performed to decelerate and stop the vehicle is referred to as “main brake operation”, and the brake operation that is performed to hold the vehicle in a stopped state is referred to as “parking brake operation”.
(8) The electric brake according to any one of (1) to (7), wherein the rotating member is a lever that boosts the driving force of the motor.
(9) The electric brake according to any one of (1) to (8), wherein the rotating member is rotatably attached to the friction material.
(10) The electric brake according to any one of (1) to (9), wherein the force transmission mechanism transmits a driving force of the motor to the rotating member as a tensile force.
(11) Any one of (3) to (10), wherein the force applying mechanism includes a mechanical force generating mechanism that mechanically generates the second tensile force based on an operation of the second brake operation member. The electric brake according to one.
(12) Any one of (3) to (10), wherein the force applying mechanism includes an electric force generation mechanism that electrically generates the second tensile force based on an operation of the second brake operation member. The electric brake according to one.
(13) The second brake operation member is an emergency brake operation member operated by a driver for an emergency brake operation, and the force applying mechanism is mechanically based on the operation of the emergency brake operation member. The electric brake according to any one of items (3) to (10), including a mechanical force generation mechanism that generates a second tensile force.
Here, the “emergency brake operation” refers to a brake operation performed to decelerate and stop the vehicle in an emergency state in which a portion related to the main brake operation of the electric brake has failed.
(14) The electric brake according to any one of (1) to (13), wherein the relay member is formed of a flexible wire.
According to this brake, a flexible relay member can be easily configured.
In this brake, the “relay member” can be composed of one wire or a plurality of wires. It can also be configured by a cable in which a plurality of wires are combined.
(15) The non-rotating body is a backing plate that is non-rotatably attached to a vehicle body, the rotating body is a drum having a friction surface on an inner peripheral surface, and the friction material is fixed to the outer peripheral surface of the brake shoe. (1) to (3), (6) to (14), wherein the brake shoe is attached to the backing plate so as to be relatively movable and the motor is fixed to the backing plate. The electric brake according to any one of the preceding claims (claim 9).
(16) The electric brake is a drive mechanism that drives the brake shoe by the rotation of the rotation member, and expands the rotation stroke of the point of action of the rotation member and transmits it to the brake shoe. The electric brake according to the item (15) including the above (claim 10).
According to this electric brake, the rotation stroke of the rotation member necessary for generating the same stroke in the brake shoe is reduced compared with the case where the rotation stroke of the rotation member is transmitted to the brake shoe without expanding the rotation stroke. As a result, the operation response of the electric brake can be easily improved.
(17) The drive mechanism includes: (a) an input member that interlocks with the rotating member; (b) an output member that interlocks with the brake shoe; and (c) an operating force of the input member on the output member. The electric brake according to (16), which includes transmitting an operation stroke in which the operation stroke of the input member is enlarged to be generated in the output member.
(18) The input member and the output member are substantially included in a plane substantially perpendicular to the rotation axis of the drum or arranged substantially parallel to the plane, and the lever is substantially parallel to the plane. The electric brake according to item (17), wherein the electric brake is rotatably connected about a right-angled rotation axis.
(19) The electric brake according to (18), wherein the rotating member is a lever that is rotatably connected around a rotation axis substantially perpendicular to the plane.
(20) The electric brake according to (19), wherein the lever and the brake shoe are operated on the plane.
According to this electric brake, no moment is generated in the input member and the output member due to the rotation of the lever, and the structure of the drive mechanism is not complicated.
(21) The electric brake according to any one of (1) to (14), wherein the rotating body is a disk, the friction material is a brake pad, and the electric brake is an electric disk brake.
(22) a drum having a friction surface and rotating together with the wheel;
A brake lining that is pressed against the friction surface to suppress rotation of the rotating body;
The brake shoe with the brake lining fixed,
A motor driven by electric power based on the operation of the brake operation member;
A main lever rotated by the motor;
An electric drum brake comprising: a drive mechanism for driving the brake shoe by the rotation of the main lever, wherein the drive mechanism enlarges the rotation stroke of the lever's operating point and transmits it to the brake shoe. .
According to this electric drum brake, the operation responsiveness of the electric drum brake can be easily improved based on the same principle as that of the electric brake described in the above item (16).
(23) The drive mechanism is
(a) an input member interlocked with the main lever;
(b) an output member interlocked with the brake shoe;
(c) The electric drum brake according to (22), which includes an intermediate lever that transmits the operating force of the input member to the output member so that the operating stroke of the input member is expanded. .
(24) The input member and the output member are substantially included in a plane substantially perpendicular to the rotation axis of the drum or arranged substantially parallel to the plane, and the intermediate lever is The electric drum brake as set forth in (23), wherein the electric drum brake is rotatably connected around a substantially perpendicular rotation axis.
(25) The electric drum brake according to (24), wherein the main lever is rotatably connected around a rotation axis substantially perpendicular to the plane.
(26) The electric drum brake according to (25), wherein the main lever, the intermediate lever, and the brake shoe are operated on the plane.
According to this electric drum brake, no moment is generated in the input member and the output member due to the rotation of the main lever, and the structure of the drive mechanism is not complicated.

  Hereinafter, some of more specific embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an overall configuration of an electric brake device including an electric drum brake according to a first embodiment of the present invention. This electric brake device is provided in a four-wheel vehicle provided with left and right front wheels FL and FR and left and right rear wheels RL and RR. The vehicle includes an engine 10 (internal combustion engine) as a prime mover and an automatic transmission 12 (hereinafter abbreviated as “A / T”) as a driving force transmission device. By driving at least one of the left and right front wheels and the left and right rear wheels, the vehicle is driven.

  The left and right front wheels FL, FR are provided with electric disc brakes 22 using a motor 20 as a drive source. On the other hand, the left and right rear wheels RL, RR are provided with electric drum brakes 32 using the motor 30 as a drive source. In the present embodiment, the motors 20 and 30 are both DC motors, but both are ultrasonic motors, the front wheel side is an ultrasonic motor, the rear wheel side is a DC motor, the front wheel side is a DC motor, The rear wheel side can be an ultrasonic motor.

  This vehicle is provided with several members operated by the driver. Some of the operation members include a brake pedal 40 as a main brake operation member (an example of a brake operation member), a parking pedal 42 as a parking brake operation member (an example of a second brake operation member), and an acceleration operation. There are an accelerator pedal 44 and a steering wheel 46 as members. When the brake pedal 40 is operated, the four-wheeled electric brakes 22 and 32 are activated, thereby braking the vehicle. When the parking pedal 42 is operated, the electric drum brakes 32 for the left and right rear wheels are actuated, thereby parking the vehicle. When the accelerator pedal 44 is operated, the driving force of the engine 10 is increased, thereby driving the vehicle. When the steering wheel 46 is rotated, the steering wheel is steered by a steering device (not shown) accordingly.

  In this electric brake device, when the brake pedal 40 is operated (main brake operation), the controller 50 causes the four-wheel electric brakes 22 and 32 to be actuated by the driving force of the motors 20 and 30. Is braked. Therefore, in this electric brake device, it is not essential for the driver to apply force to the brake pedal 40 when operating the brake pedal 40. However, in order to make the driver's pedal operation feeling equivalent to that of a conventional hydraulic brake device, if the driver applies an operation force to the brake pedal 40, the operation stroke of the brake pedal 40 changes accordingly. It is necessary to. Therefore, in this embodiment, a stroke simulator 52 is provided in the brake pedal 40 in order to cause the brake pedal 40 to generate an operation stroke corresponding to the operation force. The stroke simulator 52 includes: (a) an interlocking member 54 that interlocks with the brake pedal 40; (b) a guide member 56 that guides the interlocking member 54; and (c) an elastic force that is expanded and contracted by the movement of the interlocking member 54. And a spring 58 as an elastic member that can be increased or decreased, and the elasticity of the spring 58 causes the brake pedal 40 to generate an operation stroke having a length corresponding to the operation force.

  FIG. 2 shows details of the electric disc brake 22 for the left and right front wheels. However, only the electric disc brake 22 for the right front wheel FR is representatively shown in the figure.

  The electric disc brake 22 includes a mounting bracket 100 as a fixing member attached to a vehicle body (not shown), and a disc 104 having friction surfaces 102a and 102b on both sides and rotating with wheels. The mounting bracket 100 includes: (a) a portion that supports the pair of brake pads 106 a and 106 b so as to be movable along the rotation axis of the disc 104 at a position where the disc 104 is sandwiched from both sides; And a portion (receiving member) that receives a frictional force generated in the brake pads 106a and 106b. In the figure, an arrow X indicates a direction in which the disk 104 rotates when the vehicle body moves forward.

  Of the pair of brake pads 106a and 106b, the outer pad 106a on the outside of the vehicle body (right side in the figure) is supported by the mounting bracket 100 in a state where rotation with the disk 104 is substantially prevented when contacting the disk 104. . On the other hand, the inner pad 106b on the inner side of the vehicle body (the left side in the figure) is supported by the mounting bracket 100 in a state where the rotation with the disc 104 is positively allowed when contacting the disc 104, unlike the outer pad 106a. Has been. In the figure, the arrow Y indicates the direction of rotation of the inner pad 106b.

  However, the accompanying rotation of the inner pad 106b is not always allowed, but is prevented when the frictional force generated between the inner pad 106b and the disc 104 is smaller than the set value, and is allowed only when the set value exceeds the set value. It is like that. In order to realize such follow-up control, in this embodiment, the front end portion 110 of the inner pad 106b is engaged with the mounting bracket 100 via a spring 112 as an elastic member. When the frictional force of the inner pad 106b is smaller than the set value, the spring 112 is not elastically deformed and the inner pad 106b is prevented from being rotated. The rotation of 106b is allowed. In the present embodiment, a stopper 114 is provided that contacts the mounting bracket 100 when the amount of rotation of the inner pad 106b reaches a set value. As a result, the limit of the accompanying rotation of the inner pad 106b is restricted, and as a result, an excessive self-servo effect described later is prevented.

  The electric disc brake 22 further includes a body 120 that is movable in the direction of the rotation axis of the disc 104 and cannot be moved in the direction of rotation of the disc 104. The body 120 is slidably fitted to a plurality of pins (not shown) attached to the vehicle body so as to extend parallel to the rotational axis of the disk 104. The body 120 is attached to the vehicle body so as to straddle the disc 104 and sandwich the pair of brake pads 106a and 106b from behind. The body 120 includes (a) a reaction portion 126 that engages with the outer pad 106a from the back, (b) a pressing portion 128 that is close to the inner pad 106b in the back, and (c) the reaction portion 126 and the pressing portion 128. It is comprised so that the connection part 130 to connect may be included.

  In the pressing portion 128, the motor 20 is coaxially connected to the pressing member 134 via a ball screw mechanism 132 as a motion conversion mechanism. The pressing member 134 is supported by the pressing portion 128 so as not to rotate around the axis of the pressing member 134 and to be movable in the axial direction. Therefore, when the rotating shaft 136 of the motor 20 rotates, the rotational motion is converted into the linear motion of the pressing member 134 by the ball screw mechanism 132. As a result, the pressing member 134 is moved back and forth along the axis of the pressing member 134, and a pressing force is applied to the inner pad 106 b, and consequently the outer pad 106 a, and thereby the pair of brake pads 106 a and 106 b are applied to the disc 104. Pressed.

  In the outer pad 106a, the thickness of the back plate 140 is uniform in the disc rotation direction X, but in the inner pad 106b, the rear side (rear side in the vehicle body) from the rear side (rear side in the vehicle body) to the front side (in the vehicle body). The plate thickness is gradually reduced as the process proceeds to the front side. The back surface of the back plate 140 of the inner pad 106 b is a slope 142 with respect to the friction surface 102 of the disk 104, and the front end surface of the pressing member 134 is in contact with the inner pad 106 b on the slope 142. Further, the inclined surface 142 and the front end surface of the pressing member 134 are relatively movable along these surfaces. Therefore, in a state where the inner pad 106b is rotated, the inner pad 106b functions as a wedge between the disc 104 and the pressing member 134, and the self-servo effect of the electric disc brake 22 is realized. In the present embodiment, the axis of the pressing member 134 is perpendicular to the inclined surface 142.

  In the present embodiment, a plurality of balls 144 (or rollers or the like) are held on the front end surface of the pressing member 134 at substantially equal intervals along one circumference around the axis of the pressing member 134, and each ball 144. Is held in a rollable manner. The back plate 140 of the inner pad 106b and the pressing member 134 are brought into contact with each other by the thrust bearing 146, and the friction between the inner pad 106b and the pressing member 134 is reduced.

  Next, the operation of the electric disc brake 22 will be described.

  When the brake pedal 40 is operated by the driver and the motor 20 is rotated accordingly and the pressing member 134 is advanced from the non-operating position, the pair of brake pads 106a and 106b are pressed together against the disc 104, Thus, a frictional force is generated between each brake pad 106a, 106b and the disk 104, and the wheel is braked.

  When the frictional force of the inner pad 106b is lower than the set value and the set load of the spring 112 cannot be overcome, the spring 112 prevents the inner pad 106b from rotating, thereby preventing the occurrence of the self-servo effect. . Therefore, the wheel is braked only by driving the motor 20 in a state where the friction force of the inner pad 106b is small because the electric disk brake 22 is initially effective at the time of weak braking operation or the like.

  On the other hand, if the frictional force of the inner pad 106b becomes equal to or greater than the set value and can overcome the set load of the spring 112, the spring 112 allows the inner pad 106b to rotate. When the inner pad 106b is rotated, the inclined surface 142 moves integrally with the inner pad 106b. As a result, the distance between the friction surface 102 of the disk 104 and the inclined surface 142 increases. As a result, the inner pad 106b is strongly compressed in the thickness direction by the disk 104 and the pressing member 134, and as a result, the inner pad 106b is pressed against the disk 104 with a large force. Therefore, in a state where the frictional force of the inner pad 106b is increased because the brake pedal 40 is operated strongly (for example, a deceleration of about 0.3 to 0.6G is generated in the vehicle body), the inner pad 106b It functions as a wedge, and as a result, the wheel is braked by both the driving of the motor 20 and the self-servo effect.

  If the frictional force of the inner pad 106b further increases and the stopper 114 comes into contact with the mounting bracket 100, further follow-up of the inner pad 106b is prevented, thereby preventing excessive self-servo effect.

  FIG. 3 shows details of the electric drum brake 32 for the left and right rear wheels. However, only the electric drum brake 32 for the right rear wheel is representatively shown in the figure.

  This electric drum brake 32 includes a substantially disc-shaped backing plate 200 as a non-rotating member attached to a vehicle body (not shown), and a drum 204 that has a friction surface 202 on its inner peripheral surface and rotates with a wheel. I have. An anchor pin 206 as an anchor member and an adjuster 208 as a relay link are provided at two locations separated from each other in the diameter direction of the backing plate 200. The anchor pin 206 is fixedly attached to the backing plate 200. The anchor pin 206 extends parallel to the rotation axis of the drum 204. On the other hand, the adjuster 208 is a floating type. A pair of brake shoes 210 a and 210 b each having an arc shape are attached between the anchor pins 206 and the adjuster 208 so as to face the inner peripheral surface of the drum 204. The pair of brake shoes 210a and 210b are attached to the backing plate 200 so as to be movable along the surface thereof by shoe hold-down devices 212a and 212b. In addition, an axle shaft (not shown) is rotatably provided in a through hole provided in the center of the backing plate 200.

  The pair of brake shoes 210a and 210b are operatively connected at one end to each other by an adjuster 208, and each other end is rotatably supported by coming into contact with the anchor pin 206. One end portions of the pair of brake shoes 210a and 210b are urged by the adjuster spring 214 so as to approach each other via the adjuster 208. On the other hand, the other end portions of the pair of brake shoes 210a and 210b are urged toward the anchor pin 206 by the shoe return springs 215a and 215b. The brake linings 216a and 216b are held on the outer peripheral surfaces of the brake shoes 210a and 210b, and the pair of brake linings 216a and 216b are brought into contact with the inner peripheral surface of the drum 204, whereby the brake linings 216a and 216b and the drum 204 are contacted. A frictional force is generated between The adjuster 208 adjusts the gap between the pair of brake linings 216a and 216b and the drum 204 according to the wear of the pair of brake shoes 210a and 210b.

  Each brake shoe 210a, 210b includes a rim 220 and a web 222, and a lever 230 (main lever) is rotatably attached to one web 222 of the pair of brake shoes 210a, 210b. A pin 232 as a lever support member is fixed to the web 222 so as to be fixed in position, and one end of a lever 230 is rotatably connected to the pin 232. Both ends of a strut 236 as a force transmission member are engaged with a notch in a portion where the lever 230 and the other brake shoe 210b face each other. That is, the electric drum brake 32 is a duo-servo type in which the self-servo effect is generated in both the brake shoes 210a and 210b when the vehicle body moves forward and backward. In this embodiment, the lever 230 is attached to the brake shoe 210a that acts as a secondary shoe when the vehicle body moves forward of the pair of brake shoes 210a and 210b, but is attached to the brake shoe 210b that acts as a primary shoe. Is possible.

  The electric drum brake 32 is operated by the same rotation of the lever 230 regardless of whether the brake pedal 40 is operated or the parking pedal 42 is operated (when the parking brake is operated). Therefore, one end of the main brake cable 240 and one end of the parking brake cable 242 are connected to the other end of the lever 230. Each cable 240, 242 is composed of a plurality of wires and is flexible. A compression spring 244 is disposed coaxially with the parking brake cable 242 between the other end of the lever 230 and the backing plate 200 as in the conventional hydraulic brake device.

  The main brake cable 240 is driven by a shoe expansion actuator 250 attached to the backing plate 200. As shown in an enlarged view in FIG. 4, the shoe expansion actuator 250 has an input shaft of a speed reducer 252 connected to a rotation shaft of the motor 30, and an output shaft of the speed reducer 252 has a ball screw mechanism 254 as a motion conversion mechanism. The input member is connected, and the other end of the main brake cable 240 is connected to the output member of the ball screw mechanism 254. The ball screw mechanism 254 is a mechanism that converts the rotational motion of the motor 30 into linear motion. In the figure, reference numerals 256 and 258 both indicate brackets, and reference numerals 260 and 262 both indicate attachment bolts for attaching the brackets 256 and 258 to the backing plate 200.

  The ball screw mechanism 254 is configured such that a nut 266 as an output member is screwed to a male screw 264 as an input member via a plurality of balls (not shown). The nut 266 is fitted to a housing 267 as a fixing member so as not to rotate but to move in the axial direction. Thereby, the rotational motion of the external screw 264 is converted into the linear motion of the nut 266. An output shaft 268 is coaxially attached to the end of the nut 266 opposite to the male screw 264 side. Intrusion of dust into the sliding portions of the male screw 264, nut 266 and output shaft 268 is prevented by the housing 267 and the extendable dust boot 270.

  The coupling between the output shaft 268 and the other end of the main brake cable 240 is performed by the following configuration. That is, the cable mounting male screw 272 is formed at the opposite end of the both ends of the output shaft 268 from the ball screw mechanism 254 side, while the cable mounting nut 274 is formed at the other end of the main brake cable 240. Are combined. The cable mounting nut 274 is screwed onto the cable mounting male screw 272, and the locking nut 276 is screwed onto the cable mounting male screw 272, and the locking nut 276 is connected to the cable mounting nut 274. The cable mounting nut 274 is prevented from loosening.

  The shoe expansion actuator 250 configured as described above applies a tensile force to the main brake cable 240 when the brake pedal 40 is operated, so that the other end of the lever 230 is rotated away from the brake shoe 210b. As a result, the pair of brake shoes 210 a and 210 b are expanded by the strut 236.

  The electric drum brake 32 includes a shoe contraction mechanism effective for overcoming the self-servo effect generated by the pair of brake shoes 210a and 210b and contracting them. In this embodiment, the shoe contraction mechanism is a main brake return spring 280 stretched between the lever 230 and the backing plate 200. The main brake return spring 280 is stretched coaxially with the main brake cable 240, one end is on the other end of the lever 230, and the other end is a fixed portion of the shoe expansion actuator 250 (for example, a housing, bracket, etc. Etc.). Accordingly, when the shoe expansion actuator 250 is returned toward the initial position when the operation of the brake pedal 40 is released, the lever 230 is rotated toward the initial position by the compression force of the main brake return spring 280. However, it is not indispensable to add such a shoe contraction mechanism to the electric drum brake 32. For example, the elastic force of the adjuster spring 214 and the shoe return springs 215a and 215b, which are existing springs, is increased. It is possible to achieve the same purpose.

  The other end of the parking brake cable 242 is connected to a well-known parking control 284 as shown in FIG. The parking control 284 is mechanically actuated by the operating force of the parking pedal 42, and the tensile force applied to the parking control 284 is a direction in which the pair of brake shoes 210a and 210b expand (hereinafter simply referred to as “shoe expansion direction”). To the direction in which the lever 230 rotates.

  As shown in FIG. 3, when the brake pedal 40 is operated, the shoe extension actuator 250 applies a tensile force only to the main brake cable 240 and rotates the lever 230 in the shoe extension direction. At this time, the parking brake cable 242 is deflected. When the parking pedal 42 is operated, the parking control 284 applies a tensile force only to the parking brake cable 242 to rotate the lever 230 in the shoe extending direction, and at this time, the main brake cable 240 is bent. In this way, since the two cables 240 and 242 connected to the same lever 230 and acting at different times can be deformed together, the action of one cable is not hindered by the other cable.

  As is clear from the above description, in the present embodiment, the driving force of the motor 30 is transmitted to the lever 230 via the deformable main brake cable 240, so that the main brake cable 240 is driven when the motor 30 is driven. And the lever 230 are not slipped or frictioned at their contact portions, and as a result, the wear of the contact portions between the main brake cable 240 and the lever 230 is suppressed.

  Furthermore, according to the present embodiment, when the motor 30 is driven, slippage does not occur at the contact portion between the main brake cable 240 and the lever 230, so that it is difficult for foreign matter to enter the contact portion.

  Furthermore, according to the present embodiment, since the main brake cable 240 that connects the lever 230 and the shoe expansion actuator 250 to each other is flexible, the relative position of the shoe expansion actuator 250 with respect to the lever 230 can be changed relatively freely. Therefore, the degree of freedom of the arrangement position of the shoe expansion actuator 250 is improved.

  Furthermore, according to the present embodiment, two types of brake operations, that is, a main brake operation and a parking brake operation can be performed by the same lever 230. This makes it easy to reduce the size, weight and cost of the drum brake 32.

  Furthermore, in the present embodiment, since the main brake cable 240 and the parking brake cable 240 connected to the same lever 230 are both flexible, the parking brake cable 242 bends and the lever 230 rotates when the main brake is operated. In addition, the main brake cable 240 bends and does not hinder the rotation of the lever 230 when the parking brake is operated. Therefore, any braking operation can be performed without any special mechanism.

  By the way, assuming that the lever 230 and the shoe expansion actuator 250 are connected to each other by a rigid link so that both the force from the shoe expansion actuator 250 toward the lever 230 and the opposite force can be transmitted, in this case, the parking brake A force acts on the shoe expansion actuator 250 from the lever 230 during operation. On the other hand, in the shoe expansion actuator 250, the speed reducer 252 and the ball screw mechanism 254 perform a boosting action on the force directed from the motor 30 (input side) to the output shaft 268 (output side), but output on the contrary. For the force from the side toward the input side, a force transmission suppressing action is achieved. Therefore, in order to operate the lever 230 connected to the shoe expansion actuator 250 toward the operating position, the lever 230 causes the shoe expansion actuator 250 to operate it toward the operating position under the force transmission suppressing operation. Therefore, the operating force of the parking brake pedal 42 increases accordingly. On the other hand, in the present embodiment, when the parking brake is operated, the main brake cable 240 is bent, so that the operation of the lever 230 to the operating position is not hindered by the force transmission suppressing action. Is prevented from being shared by the main brake and the parking brake, and an increase in the operating force of the parking pedal 42 is prevented.

  That is, in the present embodiment, the brake pedal 40 constitutes an example of a “brake operation member”, the lever 230 constitutes an example of a “rotating member”, and the ball screw mechanism 254 and the main brake cable 240 are mutually connected. Together, it constitutes an example of a “force transmission mechanism”, and the main brake cable 240 constitutes an example of a “relay member”. The parking pedal 42 constitutes an example of a “second brake operation member”, and the parking control 284 and the parking brake cable 242 together constitute an example of a “force applying mechanism”, and the parking brake The cable 242 constitutes an example of a “second relay member”.

  The hardware configuration of the electric brake device has been described above. Next, the software configuration will be described.

  As shown in FIG. 1, the controller 50 is mainly configured by a computer 300 including a CPU, a ROM, and a RAM. Several sensors and switches are connected to the input side of the controller 50. Some of the sensors and switches include an operation force sensor 302, a brake pedal switch 304, an accelerator pedal switch 306, a steering angle sensor 308, a vehicle body deceleration sensor 310, a vehicle speed sensor 312, four wheel speed sensors 314, and a motor current. There is a sensor 316.

The operating force sensor 302 detects the operating force F of the brake pedal 40 and outputs a signal that defines the magnitude thereof. The brake pedal switch 304 is an example of a brake operation sensor, and outputs an OFF signal (first signal) when the brake pedal 40 is not operated and an ON signal (second signal) when the brake pedal 40 is operated. The accelerator pedal switch 306 is an example of an acceleration operation sensor, and outputs an OFF signal (first signal) when the accelerator pedal 44 is not operated and an ON signal (second signal) when the accelerator pedal 44 is operated. The steering angle sensor 308 is an example of a turning sensor, detects the rotational operation angle θ of the steering wheel 46, and outputs a signal that defines the magnitude thereof. The vehicle body deceleration sensor 310 detects a deceleration G in the longitudinal direction of the vehicle body and outputs a signal that defines the height thereof. The vehicle speed sensor 312 detects the vehicle speed V and outputs a signal that defines the magnitude thereof. Four wheel speed sensors 314 are provided for each of the four wheels, detect the wheel speed V _W of each wheel, and output a signal that defines the magnitude thereof. The motor current sensor 316 is connected to the coils of the motors 20 and 30 of the four-wheel electric brakes 22 and 32, and the current actually supplied to the motors 20 and 30 from the battery 320 as a power source via the driver 322. And a signal defining the actual supply current value I is output. The output signal is represented by a voltage. Eventually, the motor current sensor 316 outputs the actual supply current value I to the controller 50 as the voltage level.

  On the other hand, the driver 322 is connected to the output side of the controller 50. When the brake pedal 40 is operated, a command is supplied from the controller 50 to the driver 322, and in response to the command, the driver 322 supplies current from the battery 320 to the motors 20 and 30 of the electric brakes 22 and 32. Further, on the output side of the controller 50, an engine output control device (throttle control device, fuel supply control device, ignition timing control device, etc.) (not shown) of the engine 10 and a shift control device (shift solenoid, etc.) of the A / T 12 are not shown. Are connected). When the vehicle is driven, the controller 50 outputs a signal for suppressing the driving force to the engine output control device and the shift control device in order to suppress the spin of the driving wheel. That is, the controller 50 is also adapted to execute traction control.

  The ROM of the computer 300 stores several routines including a brake control routine and a friction material μ estimation routine. FIG. 5 shows a brake control routine and FIG. 6 shows a friction material μ estimation routine. In addition, the ROM also stores some data including data representing the FT characteristics with a table, a functional expression, and the like, and data representing the IT characteristics with a table, a functional expression, and the like.

  The FT characteristic represents the relationship between the operating force F of the brake pedal 40 and the braking torque value T applied to each wheel by the brakes 22 and 32, and is shown in a graph in FIG. On the other hand, the IT characteristic is a relationship between the supply current value I to the motors 20 and 30 and the braking torque value T applied to each wheel by the brakes 22 and 32 (obtained experimentally or by calculation). And is shown graphically in FIG. The FT characteristic and the IT characteristic are stored in the ROM in association with the front wheel and the rear wheel in consideration of the fact that it is normal not to be common between the front and rear.

  As shown in the figure, the IT characteristic is defined by a pattern in which the braking torque value T changes in accordance with the supply current value I. There are a plurality of patterns, and the friction coefficient μ (hereinafter simply referred to as “friction coefficient”) of the friction material. It is provided in association with a plurality of discrete values. Here, the “friction material” is a general term for a pair of brake pads 106a and 106b of the electric disc brake 22 for the front wheels and a pair of brake linings 216a and 216b of the electric drum brake 32 for the rear wheels. The same applies hereinafter.

  Hereinafter, the brake control and the friction material μ estimation by the controller 50 will be described. First, a brief description will be given.

FIG. 9 conceptually shows the relationship among the controller 50, the motors 20 and 30, the friction material 300, and the wheels 302 in this electric brake device. The controller 50 is supplied with the operation force F of the brake pedal 40 as operation information from the driver, and the controller 50 supplies the current value I to the motors 20 and 30 according to the operation force F. The motors 20 and 30 supply the driving force D to the friction material 300 according to the supplied current value I. The friction material 300 applies a braking torque T to the wheels 302 by the supplied driving force D under the actual friction coefficient μ thereof. By braking torque T is applied to the wheel 302, with the deceleration G is generated in the vehicle body deceleration G _W is generated in the wheel 302.

In this brake control, the supply current value I to the motors 20 and 30 is determined based on the operating force F of the brake pedal 40. Based on the operating force F, the target braking torque value T ^* is determined according to the FT characteristic. It is determined for each wheel, and the supply current value I is determined for each wheel according to the IT characteristic based on the target braking torque value T ^* of each wheel.

  On the other hand, in the friction material μ estimation, it is during non-braking operation, not during acceleration operation, when traveling straight through the vehicle, not during rough road travel, and during low speed travel. The brakes 22 and 32 are actuated by driving the motors 20 and 30 when there is no gear change and the A / T 12 is not shifted. Further, the supply current value I and the vehicle body deceleration G of the motors 20 and 30 during that time are acquired, and the actual braking torque value T of each wheel is acquired based on the vehicle body deceleration G. Further, among the plurality of types of IT characteristic patterns, a combination corresponding to the acquired actual braking torque value T and supply current value I is selected as the current IT characteristic pattern, and the selected one is selected. The friction material μ corresponding to the IT characteristic pattern is estimated as the actual friction material μ. The estimated value of the friction material μ is stored in the RAM.

  The friction material μ should originally be estimated for each wheel, but in this embodiment, the friction material μ is different between the front and rear wheels, but based on the premise that the friction material μ is almost equal between the left and right wheels. The wheels are estimated independently, but the left and right wheels are estimated in common.

  In the brake control, during the period in which the current estimated value of the friction material μ exists in the RAM, an IT characteristic pattern is selected according to the current estimated value of the friction material μ, and the selected I− The supply current value I is determined according to the T characteristic pattern. On the other hand, during a period when the current estimated value of the friction material μ does not exist in the RAM, if the previous estimated value exists in the RAM, an IT characteristic pattern corresponding to the previous estimated value is acquired until the current estimated value is acquired. On the other hand, if the previous estimated value does not exist in the RAM, the current estimated value is acquired for the IT characteristic pattern corresponding to the standard value (stored in the ROM) of the friction material μ. Until tentatively used.

  Next, the brake control and the friction material μ estimation will be specifically described based on the flowcharts of FIGS.

  The brake control routine of FIG. 5 is executed when the ignition switch of the vehicle is turned on. First, in step S1 (hereinafter simply referred to as “S1”, the same applies to other steps). The operation force F is detected by the operation force sensor 302. Next, in S2, it is determined whether or not the current estimated value of the friction material μ exists in the RAM. If it exists, the determination is YES, and in S3, the current estimated value of the friction material μ is read from the RAM and is used as the current use value of the friction material μ. On the other hand, if it does not exist, the determination is NO. In S4, it is determined whether or not the previous estimated value of the friction material μ exists in the RAM. If it exists, the determination is YES, and in S5, the previous estimated value of the friction material μ is read from the RAM and is used as the current use value of the friction material μ. On the other hand, if it does not exist, the determination is NO, and in S6 The standard value of the friction material μ is read from the ROM, and this is used as the current use value of the friction material μ.

In either case, the current IT characteristic pattern is then selected in S7. Of the plurality of types of IT characteristic patterns, the one corresponding to the current use value of the friction material μ is selected as the current IT characteristic pattern. Subsequently, in S8, based on the detected operating force F, a target braking torque value T ^{* for} each wheel is determined according to the FT characteristic. Thereafter, in S9, based on the determined target braking torque value T ^* of each wheel, the target value I ^{* of the} current value supplied to the motors 20 and 30 is determined for each wheel according to the selected current IT characteristic pattern. To be determined. Subsequently, in S10, a current is supplied to the motors 20 and 30 at each determined target supply current value I ^* . Thus, one execution of this routine is completed, and the process returns to S1 again.

  On the other hand, the friction material μ estimation routine of FIG. 6 is also started when the ignition switch of the vehicle is turned ON, and is initially set in S11, whereby the μ estimation flag in the RAM is set. 0. The μ estimation flag is 0, indicating that the friction material μ has not been estimated once during the vehicle travel, and 1 indicates that the friction material μ has been estimated once during the vehicle travel.

Next, in S12 to S18, success or failure of various conditions is determined. Specifically, in S12, it is determined whether or not the μ estimation flag is 0. In S13, it is determined whether or not a non-brake operation is being performed based on whether or not the brake pedal switch 304 is OFF. In S14, it is determined whether or not the acceleration operation is being performed based on whether or not the accelerator pedal switch 306 is ON. In S15, whether or not the vehicle is turning is determined based on whether or not the rotational operation angle θ of the steering wheel 46 detected by the steering angle sensor 308 is substantially zero. In S16, depending on whether the wheel 302 changes the frequency of the reference numerals of the wheel deceleration G _W is equal to or larger than the reference value exists, whether it is during rough road running of the vehicle is determined. Wheel deceleration G _W is obtained by substantially the time derivative of the detected wheel speed V _W by the wheel speed sensor 314. In S17, the vehicle speed V detected by the vehicle speed sensor 312 by whether less than the reference value V _0, whether during low-speed running of the vehicle is determined. In S18, based on the signal supplied from the A / T 12 to the controller 50, it is determined whether or not the A / T 12 is being shifted (is in a transient state). If both the determinations in S12 and S13 are YES and the determinations in S14 to S18 are both NO, the process proceeds to step S19 and subsequent steps. Otherwise, the process immediately returns to S12.

In S19, the left and right front wheel brakes 22 are actuated by simultaneously supplying current to the motor 20 of the left and right front wheel brakes 22 at the set current value I ₀ for a set time Δt. In S20, the actual supply current value I to the motor 20 is detected by the motor current sensor 316 during the operation. In S21, the vehicle body deceleration G is detected by the vehicle body deceleration sensor 310 during the operation. Thereafter, in S22, the friction material μ of the brake 22 for the left and right front wheels is estimated from the actual supply current value I and the vehicle body deceleration G. Specifically, the actual braking torque value T of the left and right front wheel brakes 22 is obtained by calculation from the vehicle body deceleration G, and the actual braking torque value T and the actual supply current value I of the plurality of types of IT characteristic patterns are obtained. The friction material μ corresponding to the IT characteristic pattern corresponding to the combination with the current value is the estimated value of the friction material μ of the brake 22 of the left and right front wheels. In S23 to S26, the same contents as in S19 to S22 are executed for the left and right rear wheel brakes 32. If the friction material μ estimation is completed for both the left and right front wheel brakes 22 and the left and right rear wheel brakes 32, the μ estimation flag is set to 1 in S27. Thereafter, the process returns to S12. After that, if S12 is executed, the μ estimation flag is 1. Therefore, the determination of S12 is continued to be NO until the current vehicle travel is finished, so that the friction material μ estimation in S19 to S26 is omitted. Is done.

  That is, in the present embodiment, the friction material μ is estimated only once during the first non-braking operation during one vehicle travel, and the estimated value of the friction material μ is maintained until the vehicle travel ends. It is not updated. However, it is of course possible to implement the present invention as updated.

  FIG. 10 is a graph showing how the brakes 22 and 32 are actuated during non-brake operation, and thereby the vehicle speed V is reduced over time.

If the above-described friction material μ estimation start condition is satisfied at time t ₁ , a current is supplied to the motor 20 of the left and right front wheel brake 22 at a set current value I ₀ , thereby starting the operation of the left and right front wheel brake 22. The As a result, the vehicle speed V decreases, but the gradient, that is, the vehicle body deceleration G at this time depends on the friction material μ of the brake 22 of the left and right front wheels, and when the friction material μ is high, a high vehicle body deceleration G ₁ and friction material When μ is low, a low vehicle body deceleration G ₂ is generated. When the set time Δt elapses from the timing t ₁ and reaches the timing t ₂ , the current supply to the motor 20 is stopped and the motor 20 is restored to the initial state.

Thereafter, at a time t ₃ when a slight time has elapsed, a current is supplied to the motor 30 of the left and right rear wheel brake 32 at a set current value I ₀ , thereby starting the operation of the left and right rear wheel brake 32. . As a result, as in the above case, the vehicle speed V decreases, but the gradient at this time, that is, the vehicle body deceleration G, depends on the friction material μ of the brake 32 of the left and right rear wheels, and as in the above case, the friction material. When μ is high, a high vehicle body deceleration G ₃ is generated, and when μ is low, a low vehicle body deceleration G ₄ is generated. When the set time Δt elapses from the timing t ₃ and reaches the timing t ₄ , the current supply to the motor 30 is stopped and the motor 30 is restored to the initial state.

  Next, the electric drum brake which is 2nd Embodiment of this invention is demonstrated. However, since the present embodiment has many elements in common with the previous first embodiment, detailed description is omitted by using the same reference numerals for common elements, and only different elements will be described in detail.

  FIG. 11 shows the overall configuration of an electric brake device including the electric drum brake according to the present embodiment. In the present embodiment, an operation force sensor 302, a brake pedal switch 304, and a parking pedal switch 400 (an example of a parking brake operation sensor) are provided as sensors and switches. The parking pedal switch 400 outputs a parking brake operation signal that is OFF (first signal) when not operated and ON (second signal) when operated. These sensors and switches are connected to the input side of the controller 402. The controller 402 is composed mainly of a computer 404. On the output side of the controller 402, via a driver 322 to which a battery 320 is connected, an ultrasonic motor 408 of the electric disc brake 22 for the left and right front wheels, and a DC motor 410 of the electric drum brake 32 for the left and right rear wheels, Is connected. The controller 402 utilizes the fact that the ultrasonic motor 408 generates a sufficiently large self-holding torque when the ultrasonic motor 408 is in an OFF state, and when the parking brake is operated, the ultrasonic motor 408 is turned ON to operate the electric disc brake brake 22. Later, in the operating state, the ultrasonic motor 408 is turned off to hold the vehicle in a stopped state. In this embodiment, an emergency brake pedal 412 (an example of an emergency brake operation member) is provided as an operation member. The electric drum brake 32 is mechanically operated by the operating force of the emergency brake pedal 412 in an emergency when the vehicle braking by the motors 408 and 410 becomes defective. The emergency brake pedal 412 is connected to the lever 230 via an emergency brake control 414 and an emergency brake cable 416. The configurations of the emergency brake controller 414 and the emergency brake cable 416 are the same as the parking control 284 and the parking brake cable 242 in the previous embodiment.

  The ROM of the computer 404 stores a brake control routine represented by a flowchart in FIG. This routine is started when the ignition switch of the vehicle is operated to ON. First, in S401, it is determined whether or not the main brake is being operated based on whether or not the brake pedal switch 304 is ON. Is done. If it is assumed that the main brake is not being operated this time, the determination is NO, and in S402, the parking brake operation is started depending on whether or not the output signal of the parking pedal switch 400 has changed from OFF to ON. It is determined whether or not. If it is assumed that this time is not the start time, the determination is NO, and whether or not the parking brake operation is ended depending on whether or not the output signal of the parking pedal switch 400 changes from ON to OFF in S403. Is determined. If it is assumed that this time is not the end time, the determination is no and the process returns to S401.

  If it is assumed at this time that the main brake is being operated, the determination in S401 is YES, and the operation force F of the brake pedal 40 is detected by the operation force sensor 302 in S404, and then the detected operation in S405. The electric disk brake 22 and the electric drum brake 32 are operated by supplying current to the ultrasonic motor 408 and the DC motor 410 based on the force F. As a result, the vehicle is braked. Thereafter, the process returns to S401.

  On the other hand, this time, assuming that the parking brake operation is started and not the main brake operation, the determination in S401 is NO, the determination in S402 is YES, and the ultrasonic motor 408 is turned on in S406. Then, the electric disc brake 22 is activated, and after a predetermined time, the ultrasonic motor 408 is turned off at that position in S407. Thereby, a self-holding torque is generated in the ultrasonic motor 408, and the electric disc brake 22 is held in the operating state by the self-holding torque, and as a result, the vehicle is held in the stopped state. Thereafter, the process returns to S401.

  In addition, if it is assumed that the parking brake operation is ended and not the main brake operation, the determination in S401 is NO, the determination in S402 is NO, the determination in S403 is YES, and the ultrasonic motor 408 is determined in S408. In step S409, the ultrasonic motor 408 is turned off. Thereafter, the process returns to S401.

  Next, an electric drum brake according to a third embodiment of the present invention will be described. The electric drum brake is provided in the electric brake device, and the software configuration of the electric brake device is the same as that of the first embodiment. In addition, since the basic configuration of the electric drum brake is the same as that of the electric drum brake 32 in the first embodiment, detailed description is omitted by using the same reference numerals for common elements, and only different elements are used. This will be described in detail.

  As shown in FIG. 13, the electric drum brake 450 in this embodiment is configured such that the strut 236 is changed to a drive mechanism 452 with respect to the electric drum brake 32.

  Similarly to the strut 236, the drive mechanism 452 drives the brake shoe 210b (primary shoe) with a lever 230 (main lever) as a rotating member. However, unlike the strut 236 that transmits the rotation stroke of the lever 230 to the brake shoe 210b as it is, the drive mechanism 452 enlarges the rotation stroke of the lever 230 and transmits it to the brake shoe 210b.

  The drive mechanism 452 includes an input member 460 that interlocks with the lever 230 at a position corresponding to the strut 236. The input member 460 has a rod shape and is disposed in a design reference plane that is a plane perpendicular to the rotation axis of the drum 204. The input member 460 is supported at both ends by the lever 230 and the web 222 of the brake shoe 210b. However, unlike the strut 236, the input member 460 has a brake shoe so that a large axial clearance remains between the input shoe 460 and the brake shoe 210b as shown in an enlarged view in FIG. 210b is supported. The input member 460 is prevented from coming into contact with the brake shoe 210b when the electric drum brake 450 is operated.

  The drive mechanism 452 also includes a lever 462 (intermediate lever) that is rotatably connected to the anchor pin 206, as shown in FIG. The lever 462 also has a rod shape and is disposed in the design reference plane. As shown in FIG. 14, the lever 462 is passed through a through hole 464 formed in the central portion of the input member 460 in the axial direction, and the lever 462 moves in the axial direction toward the brake shoe 210 b of the input member 460. 462 is transmitted as a rotation in a direction in which the free end (tip) thereof approaches the brake shoe 210b.

  Further, as shown in FIG. 13, the drive mechanism 452 has an output member 468 interlocked with the brake shoe 210 b substantially parallel to the input member 460 and on the side opposite to the rotation center point of the lever 462 with respect to the input member 460. Prepared for position. The output member 468 also has a rod shape and is disposed in the design reference plane. Eventually, the input member 460, the lever 462, and the output member 468 are arranged in the same design reference plane. The output member 468 is supported at both ends of the output member 468 by the tip of the lever 462 and the web 222 of the brake shoe 210b. The output member 468 and the lever 462 are rotatably connected by a pin 470. The output member 468 is shown enlarged in FIG. 15 (BB sectional view in FIG. 13).

  As shown in FIG. 13, the drive mechanism 452 further includes a return spring 472 that constantly urges the lever 462 in a direction in which the lever 462 rotates in a direction in which the tip end portion thereof is separated from the brake shoe 210b. The return spring 472 is hung on the lever 462 and the lever 230.

  In the drive mechanism 452 configured as described above, when the shoe extension actuator 250 using the motor 30 as a drive source is operated to rotate the lever 230 in a direction approaching the brake shoe 210b, The input member 460 is linearly moved toward the brake shoe 210b (to the right in the drawing). By this linear motion, the lever 462 is rotated in a direction approaching the brake shoe 210b, and by this rotation, the output member 468 is rotated in a direction in which the brake shoe 210b is pressed. As a result, the lever 462 is fixed to the brake shoe 210b. The brake lining 216 b is pressed against the friction surface of the drum 204. The connecting point between the lever 462 and the output member 468 is positioned at a position farther from the pivot support point of the lever 462 than the connecting point between the lever 462 and the input member 460. Therefore, the rotation stroke of the lever 230, that is, the operation stroke of the input member 460 is enlarged according to the lever ratio of the lever 462 and transmitted to the output member 468.

  The following effects can be obtained by such a stroke expansion mechanism.

  During non-braking operation, a relatively large initial clearance exists between the brake lining 216 b and the drum 204. In the present embodiment, the rotation stroke of the lever 230 is enlarged and transmitted to the brake shoe 210b. Therefore, according to this embodiment, a relatively large initial clearance can be quickly eliminated by a relatively small rotation stroke, and the operation responsiveness of the electric drum brake 450 is improved.

  Even after the disappearance of the initial clearance, that is, in a region where the apparent rigidity is high only when the brake shoe 210b is operated, the rotation stroke of the lever 230 is expanded and transmitted to the brake shoe 210b. Therefore, according to the present embodiment, the rotation stroke of the lever 230 necessary for generating the same stroke in the brake shoe 210b is reduced, and the rotation of the lever 230 required for generating the same friction force in the brake lining 216b is performed. As a result, the operation stroke of the electric drum brake 450 is improved.

  As the brake linings 216a, 216b wear, the pivot stroke of the lever 230 required to operate the brake shoe 210b increases, thereby increasing the maximum rotation angle of the motor 30. In the present embodiment, the rotation stroke of the lever 230 is enlarged and transmitted to the brake shoe 210b. Therefore, according to the present embodiment, even if the brake linings 216a and 216b are worn, the maximum rotation angle of the motor 30 does not have to be so large, and the driving force of the motor 30 is stable over the entire change range of the rotation angle of the motor 30. It becomes easy to control with high accuracy.

  Next, an electric drum brake according to a fourth embodiment of the present invention will be described. However, since this embodiment is different from the third embodiment only in the configuration of the drive mechanism and is common to other elements, detailed description is omitted by using the same reference numerals for common elements. Only the configuration of the drive mechanism will be described in detail.

  In the drive mechanism 452 according to the third embodiment, as shown in FIG. 14, the rotation plane of the lever 462 (the trajectory drawn by the rotation of the lever 462) and the rotation plane of the web 222 of the brake shoe 210b are accurately set to each other. In contrast, the rotation plane of the lever 230 and the rotation plane of the lever 464 do not exactly match each other. Therefore, a moment is generated in the input member 460 when the electric drum brake 450 is operated. On the other hand, in the present embodiment, the lever 500 in the electric drum brake has a symmetrical shape with respect to one plane including the web 222 of the brake shoe 210a as shown in FIG. The mechanism 502 is configured such that both ends of the input member 504 are linked to the lever 500, the lever 462, and the brake shoe 210b. Thereby, in this embodiment, not only the rotation plane of the lever 462 and the rotation plane of the web 222 of the brake shoe 210b exactly coincide with each other, but also the rotation plane of the lever 500 and the rotation plane of the lever 462. And exactly match each other. Therefore, according to the present embodiment, no moment is generated in the input member 504 when the electric drum brake is operated.

  Although several embodiments of the present invention have been described in detail with reference to the drawings, various modifications and improvements can be made based on the knowledge of those skilled in the art without departing from the scope of the claims. Of course, the present invention can be carried out in the above-described form.

1 is a system diagram showing an overall configuration of an electric brake device including an electric drum brake according to a first embodiment of the present invention. FIG. 2 is an enlarged plan sectional view showing the electric disc brake in FIG. 1. It is side surface sectional drawing which expands and shows the electric drum brake in FIG. FIG. 4 is a partial cross-sectional side view showing an enlarged shoe extension actuator in FIG. 3. It is a flowchart which shows the brake control routine memorize | stored in ROM of the computer of FIG. It is a flowchart which shows the friction material micro estimation routine memorize | stored in the said ROM. It is a graph which shows the FT characteristic in the said embodiment. It is a graph which shows the IT characteristic in the said embodiment. It is a systematic diagram which shows notionally the structure of the said embodiment. It is a graph which shows a mode that the vehicle speed V is reduced by the action | operation of a brake at the time of non-brake operation in the said embodiment. It is a systematic diagram which shows the whole structure of the electric brake device containing the electric drum brake which is 2nd Embodiment of this invention. 12 is a flowchart showing a brake control routine stored in a ROM of a computer of the controller in FIG. It is a side view which shows the electric drum brake which is 3rd Embodiment of this invention. It is AA sectional drawing in FIG. It is BB sectional drawing in FIG. It is sectional drawing which shows the drive mechanism of the electric drum brake which is 4th Embodiment of this invention.

Explanation of symbols

  30: Motor 32, 504: Electric drum brake 40: Brake pedal (first brake operation member) 42: Parking pedal (second brake operation member) 50, 402: Controller 204: Drum 210a, 210b: Brake shoes 216a, 216b : Brake lining 230, 500: lever 284: parking control 320: battery 240: main brake cable (one relay member of claim 3, other relay member of claims 4, 5) 242: parking brake cable (claim 3) 408: Ultrasonic motor 410: DC motor 412: Emergency brake pedal 414: Emergency brake control 416: Emergency brake cable 452, 502: Drive mechanism 60,504: an input member 462: a lever 468: the output member

Claims (11)

A rotating body having a friction surface and rotating together with the wheel;
A non-rotating body,
A friction material attached to the non-rotating body so as to be relatively movable, and pressed against the friction surface to suppress the rotation of the rotating body;
A motor driven by electric power based on the operation of the brake operation member;
A rotation member provided at one end so as to be rotatable around a rotation axis, and based on the rotation, a rotation member that presses the friction material against the friction surface;
In the electric brake including a force transmission mechanism that transmits the driving force of the motor to the rotating member,
The motor is fixed to the non-rotating body to which the friction material is attached so as to be relatively movable, and the force transmission mechanism uses the driving force of the motor as the rotating member and has a flexible relay member. And one end of the relay member is coaxially fixed to the output member of the motion conversion mechanism that converts the rotational motion of the rotating shaft of the motor into the linear motion of the output member, The electric brake, wherein the other end of the relay member is connected to the other end of the rotating member opposite to the one end.   The other end portion of the relay member extends to the other end portion of the rotation member in a direction substantially orthogonal to the direction of the force applied to the one end portion of the relay member by the motion conversion mechanism and the rotation The force transmission mechanism is connected by contact with a plane parallel to the plane of the member, and the force transmission mechanism is a contact portion between the other end of the relay member and the other end of the rotating member. 2. The structure according to claim 1, wherein wear caused by a difference between a linear movement locus of the one end portion and an arcuate movement locus of the other end portion of the rotating member is suppressed by bending of the relay member. Electric brake.   Two of the relay members are directly connected to the rotating member, and the force transmission mechanism transmits the driving force of the motor to the rotating member via one relay member. The type brake includes a force application mechanism that applies a tensile force of a second brake operation member different from the first brake operation member as the brake operation member to the rotating member via the other relay member. The electric brake according to 1 or 2. A rotating body having a friction surface and rotating together with the wheel;
A motor driven by electric power based on the operation of the first brake operation member;
A rotation member provided at one end so as to be rotatable around a rotation axis, and based on the rotation, a rotation member that presses the friction material against the friction surface;
The flexible member includes two flexible relay members that are directly connected to the rotating member, and one of the two relay members has a second brake operation separate from the first brake operation member. A tensile force based on the operation force of the member is applied, the driving force of the motor is applied to the other of the two relay members, and one end portion of the other relay member rotates the rotation shaft of the motor. The other end of the rotating member is opposite to the one end of the rotating member, and the other end of the other relay member is coaxially fixed to the output member of the motion converting mechanism that converts the motion into a linear motion of the output member. Electric brake characterized in that it is connected to.   A plane in which the other end of the other relay member extends to the other end of the rotating member in a direction substantially perpendicular to the direction of the force applied to the one end of the other relay member by the motion conversion mechanism. And a contact portion between the other end of the other relay member and the other end of the rotating member. Wear caused by the difference between the linear movement locus of the one end of the other relay member and the arcuate movement locus of the other end of the rotating member is suppressed by the deflection of the other relay member. The electric brake according to claim 4, having a structure.   The electric brake according to claim 4 or 5, wherein the electric brake includes a non-rotating body that holds the friction material in a relatively movable manner, and the motor is fixed to the non-rotating body.   The first brake operation member is a member operated by the driver to decelerate and stop the vehicle, and the second brake operation member is a member operated by the driver to keep the vehicle in a stopped state. The electric brake according to any one of claims 3 to 6.   The electric brake according to any one of claims 1 to 7, wherein the relay member is formed of a flexible wire.   Brake running in which the non-rotating body is a backing plate that is non-rotatably attached to a vehicle body, the rotating body is a drum having a friction surface on an inner peripheral surface, and the friction material is fixed to an outer peripheral surface of a brake shoe. The electric brake according to claim 1, wherein the brake shoe is attached to the backing plate so as to be relatively movable, and the motor is fixed to the backing plate.   The electric brake includes a drive mechanism that drives the brake shoe by the rotation of the rotation member, and expands the rotation stroke of the action point of the rotation member and transmits it to the brake shoe. The electric brake according to claim 9.   The drive mechanism includes: (a) an input member that interlocks with the rotating member; (b) an output member that interlocks with the brake shoe; and (c) an operating force of the input member on the output member, The electric brake according to claim 10, further comprising transmitting an operation stroke obtained by expanding the operation stroke to the output member.

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