JPH1199934A - Motor-driven type brake - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain abrasion between members in a power transmitting mechanism by transmitting the driving force of a motor to a rotationally moving member through a relaying member having flexibility. SOLUTION: In this motor-driven type brake, driving force of a motor is transmitted to a lever 230 through a deformable main brake cable 240, therefore at driving the motor, slide namely abrasion is not generated on the contact part between the main brake cable 240 and the lever 230. Further at driving the motor, slide is not generated on the contact part between the main brake cable 240 and the lever 230. The main brake cable 240 connecting the lever 230 to shoe spreading actuator 250 is flexible. Hereby, the degree of freedom for the arranging position of the shoe spreading actuator 250 is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric brake using a motor as a drive source.

[0002]

2. Description of the Related Art Generally, the above-mentioned electric brake includes (a) a rotating body having a friction surface and rotating together with a wheel; (b) a friction material which is pressed against the friction surface to suppress rotation of the rotating body; c)
Based on the operation of brake operating members such as a brake pedal,
A motor driven by electric power, (d) a rotating member that presses the friction material against the friction surface by rotation, and (e) a force transmission mechanism that transmits a driving force of the motor to the rotating member. Is done.

A conventional example of this electric brake is described in European Patent Application Publication No. EP 0594233A1. In this electric brake, the force transmission mechanism has a structure in which the driving force of the motor is transmitted to a lever as a rotating member via a rigid shaft driven in a straight line by the driving force of the motor. It had been.

[0004]

In this conventional electric brake, when driven by a motor, each point on the shaft moves along a straight line, while the point on the shaft moves. Move along a circle. In this way, the movement trajectory differs between each point on the shaft and each point on the lever. Therefore, in the conventional electric brake, when driven by the motor, slipping or friction occurs between the shaft and the lever in a direction intersecting with the moving direction of the shaft, and thereby,
There is a problem that the contact portion between the shaft and the lever is easily worn.

The present invention has been made in view 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.

[0006] This problem is solved by the following electric brake. In the following description, each aspect of the present invention will be described in the same form as the claims, with the respective items numbered. This is to clarify the possibility of adopting the features described in each section in combination.

(1) A rotating body having a friction surface and rotating together with the wheel, a friction material pressed against the friction surface to suppress the rotation of the rotating body, and an electric power generated by operating a brake operating member. An electric brake including: a driven motor; a rotating member that presses the friction material against the friction surface by rotation; and a force transmission mechanism that transmits a driving force of the motor to the rotating member. The electric brake according to claim 1, wherein the mechanism has a structure for transmitting a driving force of the motor to the rotating member via a flexible relay member. In this brake, the driving force of the motor is transmitted to the rotating member via a relay member having flexibility. Therefore, according to this brake, when the motor is driven, slipping or friction does not occur at the contact portion between the relay member and the rotating member, so that the wear of the contact portion between the two members in the force transmission mechanism is suppressed. Is done. In this brake, the “flexible relay member” may be any material that is more easily deformed than a rigid relay member, and may be formed of a flexible wire, a flexible rod, or a flexible leaf described later. It can be composed of a spring. (2) The electric brake according to (1), wherein the rotating member is a lever that boosts the driving force of the motor. (3) The electric brake according to (1) or (2), wherein the rotating member is rotatably attached to the friction material. (4) The force transmitting mechanism transmits the driving force of the motor to the rotating member as a pulling force (1) to (3).
The electric brake according to any one of the above items. (5) The force transmitting mechanism transmits the driving force of the motor to the rotating member as a pulling force, and the relay member is configured by a flexible wire (1) to
The electric brake according to any one of the above items (4) [Claim 2]. According to this brake, a flexible relay member can be easily configured. In this brake, the “relay member” can be configured by one wire or a plurality of wires. It is also possible to configure a cable in which a plurality of wires are twisted. (6) Further, based on the operation of the second brake operation member,
(1) The electric type according to any one of (1) to (5), including a force applying mechanism for applying a second tensile force to the rotating member via a second relay member formed of a flexible wire. Brake [Claim 3]. According to this brake, two types of brake operations can be performed by the same rotating member. Therefore, compared to a case where a rotating member is provided for each type of brake operation, the size, weight, and cost of the brake device are reduced. It becomes easy. In this brake, regardless of the type of brake operation, if a pulling force is applied to the rotating member, the rotating member is rotated in the same direction. Therefore, when the relay member that applies the pulling force to the rotating member is not flexible, even if an attempt is made to apply the pulling force to the rotating member via the relay member for a certain brake operation, the application is not performed. It is obstructed by the other relay member. On the other hand, in this brake, any of the relay members has flexibility, and if an attempt is made to apply a pulling force to the rotating member via one of the relay members for one brake operation. Accordingly, the other relay member bends accordingly. Therefore,
According to this brake, by using the flexibility of the relay member, it is possible to prevent one brake operation from being hindered by the relay member for the other brake operation without a complicated mechanism. (7) The brake operation member is a main brake operation member operated by a driver for a main brake operation, and the second brake operation member is a parking brake operated by a driver for a parking brake operation. The electric brake according to item (6), which is a brake operation member. Here, the “main brake operation” refers to a main brake operation normally performed to decelerate and stop the vehicle. The “parking brake operation” refers to a brake operation performed to hold the vehicle in a stopped state. (8) The electric brake according to (7), wherein the second force applying mechanism includes a mechanical force generating mechanism that mechanically generates the second pulling force based on an operation of the parking brake operation member. (9) The electric brake according to (7), wherein the force applying mechanism includes an electric force generating mechanism that electrically generates the second pulling force based on an operation of the parking brake operating member. (10) The brake operation member is a main brake operation member operated by a driver for a main brake operation, and the second brake operation member is an emergency brake operated by a driver for an emergency brake operation. The electric actuating device according to claim 6, which is a brake operating member, wherein the force applying mechanism includes a mechanical force generating mechanism that mechanically generates the second tensile force based on an operation of the emergency brake operating member. brake.
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. (11) The electric brake according to any one of (1) to (10), wherein the rotating body is a drum, the friction material is a brake lining, and the electric brake is an electric drum brake. (12) The electric brake according to any one of (1) to (10), wherein the rotating body is a disk, the friction material is a brake pad, and the electric brake is an electric disk brake. (13) The electric brake is a drum type in which the rotating body and the friction material are provided as a drum and a brake lining, respectively, and the brake lining is fixed to a brake shoe. The electric brake according to any one of (1) to (10), including a drive mechanism that drives the brake shoe, and includes a mechanism that enlarges a rotation stroke of a rotation member and transmits the rotation stroke to the brake shoe. Claim 4]. According to this electric brake, the turning stroke of the turning member required to cause the same stroke on the brake shoe is smaller than when the turning stroke of the turning member is transmitted to the brake shoe without expanding the turning stroke. As a result, the operation responsiveness of the electric brake can be easily improved. (14) the drive mechanism, (a) an input member interlocked with the rotating member, (b) an output member interlocked with the brake shoe, (c) the operating force of the input member to the output member, (13) The electric brake according to the above (13), which includes transmitting an operating stroke obtained by expanding the operating stroke of the input member to the output member. (15) The input member and the output member are substantially included in a plane substantially perpendicular to the rotation axis of the drum, or are disposed substantially parallel to the plane, and the lever is substantially parallel to the plane. The electric brake according to item (14), which is rotatably connected around a right-angle rotation axis. (16) The electric brake according to the mode (15), wherein the turning member is a lever rotatably connected around a turning axis substantially perpendicular to the plane. (17) The electric brake according to (16), wherein the lever and the brake shoe are operated on the plane. According to the 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 does not need to be complicated. (18) a drum having a friction surface and rotating with the wheel,
A brake lining that is pressed against the friction surface to suppress rotation of the rotating body, a brake shoe to which the brake lining is fixed, a motor driven by electric power based on operation of a brake operation member, and a rotation by the motor. A main lever to be moved, and a drive mechanism for driving the brake shoe by turning the main lever, the drive mechanism extending the turning stroke of the lever and transmitting the same to the brake shoe. Electric drum brake. According to this electric drum brake, (1)
According to the same principle as the electric brake described in the item 4), the operation responsiveness of the electric drum brake can be easily improved. (19) the drive mechanism, (a) an input member interlocked with the main lever, (b) an output member interlocked with the brake shoe, (c) input the operating force of the input member to the output member, (16) The electric drum brake according to (16), including an intermediate lever that transmits an operation stroke obtained by enlarging the operation stroke of the member to the output member. (20) the input member and the output member are substantially included in a plane substantially perpendicular to the rotation axis of the drum, or are disposed substantially in parallel with the plane, and the intermediate lever is disposed between the plane and the plane. The electric drum brake according to item (19), wherein the electric drum brake is rotatably connected around a substantially perpendicular rotation axis. (21) The electric drum brake according to (20), wherein the main lever is rotatably connected around a rotation axis substantially perpendicular to the plane. (22) The electric drum brake according to (21), 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 does not need to be complicated.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Some specific embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows the 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, FR and left and right rear wheels RL, RR. This 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.
/ T12 drives at least one of the left and right front wheels and the left and right rear wheels to drive the vehicle.

The left and right front wheels FL and FR are provided with electric disc brakes 22 driven by a motor 20. On the other hand, the left and right rear wheels RL, RR are provided with an electric drum brake 32 driven by the motor 30. In the present embodiment, both motors 20 and 30 are D
It is a C motor, 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 can be a DC motor, and the rear wheel side can be an ultrasonic motor.

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

In this electric brake device, when the brake pedal 40 is operated (when the main brake is operated), the controller 50 controls the electric brakes 22 and 32 of the four wheels.
Is operated by the driving force of the motors 20 and 30, whereby the vehicle is braked. Therefore, in this electric brake device, it is not essential that the driver applies a force to the brake pedal 40 when the brake pedal 40 is operated. However, in order to make the driver's pedal operation feeling equivalent to that of the 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 the present embodiment, a stroke simulator 52 is provided on 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. A spring 58 is provided as an elastic member for increasing or decreasing the force, 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 brakes 22 for the left and right front wheels. However, in the figure, only the electric disk brake 22 for the right front wheel FR is representatively shown.

The electric disc brake 22 includes a mounting bracket 100 as a fixing member mounted on a vehicle body (not shown), and friction surfaces 102a, 102 on both sides.
02b, which rotates with the wheels. The mounting bracket 100 is (a)
The pair of brake pads 106a and 106b are
And (b) the respective brake pads 106a and 106 at the time of contacting the disk 104 with the disk 104 at a position sandwiching the disk 04 from both sides.
b) (a receiving member) for receiving the frictional force generated in b. In the figure, arrow X indicates disc 1
04 indicates the direction of rotation.

A pair of brake pads 106a, 106b
Outer pad 10 on the outside of the vehicle body (right side in the figure)
6a is supported by the mounting bracket 100 in a state where the rotation with the disk 104 is substantially prevented when the disk is in contact with the disk 104. On the other hand, the inner pad 106b on the inner side of the vehicle body (left side in the figure)
Unlike the outer pad 106a, the outer pad 106a is supported by the mounting bracket 100 in a state where it is positively allowed to rotate with the disk 104 when in contact with the disk 104. In the figure, the arrow Y indicates the direction of rotation of the inner pad 106b.

However, the 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 disk 104 is smaller than a set value, and only when the frictional force exceeds the set value. It is now acceptable. In order to realize such a swiveling control, in the present embodiment, the front end 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 rotation of the inner pad 106b is prevented. The rotation of 106b is allowed.
In the present embodiment, a stopper 114 is provided which comes into contact with the mounting bracket 100 when the amount of rotation of the inner pad 106b reaches a set value. As a result, the rotation limit of the inner pad 106b is restricted, and the self-servo effect described later is prevented from becoming excessive.

The electric disc brake 22 is further movable in the direction of the rotation axis of the disc 104.
A body 120 that is immovable in the rotation direction 04 is provided. The body 120 is slidably fitted to a plurality of pins (not shown) attached to the vehicle body in a posture extending in parallel with the rotation axis of the disk 104. The body 120 is
A pair of brake pads 106
a, 106b are attached to the vehicle body in a posture sandwiching them from behind. The body 120 includes (a) a reaction portion 126 that is engaged with the outer pad 106a from behind, and (b) a pressing portion 128 that is adjacent to the inner pad 106b behind.
And (c) a connecting portion 130 for connecting the reaction portion 126 and the pressing portion 128 to each other.

In the pressing portion 128, the motor 20 is coaxially connected to a pressing member 134 via a ball screw mechanism 132 as a motion converting 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 rotation shaft 136 of the motor 20 rotates, the rotational motion is transmitted to the pressing member 13 by the ball screw mechanism 132.
4 linear motion. Thereby, the pressing member 13
4 is moved back and forth along the axis thereof, and the movement applies a pressing force to the inner pad 106b and, consequently, the outer pad 106a, whereby the pair of brake pads 106a and 106b are pressed against the disk 104.

In the outer pad 106a, the back plate 1
Although the plate thickness of the inner pad 40 is uniform in the disk rotation direction X, the thickness of the inner pad 106b increases from the rear side (rear side in the vehicle body) to the front side (front side in the vehicle body) in the corotating direction Y thereof. Is gradually reduced. The back surface of the back plate 140 of the inner pad 106b is the slope 1 with respect to the friction surface 102 of the disk 104.
42, and the front end face of the pressing member 134 is
Is in contact with the inner pad 106b. 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 rotates, the inner pad 106b
4 functions as a wedge between the pressing member 134 and the self-servo effect of the electric disc brake 22 is realized. In this embodiment, the pressing member 1
The axis of 34 is perpendicular to the slope 142.

In the present embodiment, a plurality of balls 144 (rollers or the like) are held on the front end face of the pressing member 134 at substantially equal intervals along one circumference around the axis of the pressing member 134. Each ball 144 is held rotatably. Back plate 1 of inner pad 106b
Since the thrust bearing 146 and the pressing member 134 are in contact with each other, the friction between the inner pad 106b and the pressing member 134 is reduced.

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

When the driver operates the brake pedal 40 and rotates the motor 20 to move the pressing member 134 forward from the inoperative position, the pair of brake pads 106a and 106b
, So that each brake pad 106a,
A frictional force is generated between 106b and disk 104, and the wheels are braked.

In a state where 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 together, thereby generating a self-servo effect. Will be blocked. Therefore, the wheels are braked only by driving the motor 20 in a state where the frictional force of the inner pad 106b is small because the electric disc brake 22 is initially effective, such as when the brake operation is weak.

On the other hand, when the frictional force of the inner pad 106b becomes equal to or more than the set value and the state in which the set load of the spring 112 can be overcome, the spring 11
2 allows the inner pad 106b to rotate. When the inner pad 106b rotates, the slope 142 moves integrally with the inner pad 106b.
4 increases the distance between the friction surface 102 and the inclined surface 142. As a result, the inner pad 106b is strongly compressed in the plate thickness direction by the disc 104 and the pressing member 134, and as a result, the inner pad 106b
Is pressed. Accordingly, since the brake pedal 40 is operated strongly (for example, to the extent that a deceleration of about 0.3 to 0.6 G occurs in the vehicle body), the inner pad 106
b, the inner pad 10
6b functions as a wedge, so that the wheels are braked by both the driving of the motor 20 and the self-servo effect.

The frictional force of the inner pad 106b further increases, and the stopper 114 is attached to the mounting bracket 10
When the inner pad 106b contacts 0, further rotation of the inner pad 106b is prevented, thereby preventing the self-servo effect from becoming excessive.

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

The 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 which has a friction surface 202 on an inner peripheral surface and rotates together with wheels. 204. An anchor pin 206 as an anchor member and an adjuster 208 as a relay link are provided at two locations separated in the diameter direction of the backing plate 200, respectively. 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 of a floating type. Between the anchor pin 206 and the adjuster 208, a pair of brake shoes 21 each forming an arc shape are provided.
0 a and 210 b are attached so as to face the inner peripheral surface of the drum 204. A pair of brake shoes 210
a, 210b are shoe hold-down devices 212a,
It is movably attached to the backing plate 200 along its surface by 212b. An axle shaft (not shown) is rotatably protruded from a through hole provided at the center of the backing plate 200.

A pair of brake shoes 210a, 210b
One end is operatively connected to each other by an adjuster 208, and the other end is rotatably supported by being in contact with an anchor pin 206. One ends of the pair of brake shoes 210a and 210b are urged by an adjuster spring 214 in a direction approaching each other via an adjuster 208. On the other hand, the other ends of the pair of brake shoes 210a and 210b are connected to the anchor pins 2 by the shoe return springs 215a and 215b.
It is biased toward 06. Each brake shoe 21
Brake lining 216 on the outer peripheral surfaces of
a, 216b are held, and the pair of brake linings 216a, 216b are brought into contact with the inner peripheral surface of the drum 204, whereby the brake linings 21
A frictional force is generated between the drums 6a and 216b and the drum 204. The adjuster 208 includes a pair of brake shoes 210.
The gap between the pair of brake linings 216a, 216b and the drum 204 is adjusted according to the wear of the a and 210b.

Each brake shoe 210a, 210b comprises a rim 220 and a web 222, and one web 22 of a pair of brake shoes 210a, 210b.
A lever 230 (main lever) is rotatably attached to 2. A pin 232 as a lever support member is fixedly attached to the web 222, and the pin 2
One end of a lever 230 is rotatably connected to 32. This lever 230 and the other brake shoe 210b
Both ends of a strut 236 as a force transmitting member are engaged with the notches in the portions facing each other. In other words, the electric drum brake 32 is used for any of the brake shoes 210a,
The duo-servo type 210b also has a self-servo effect. In this embodiment, the lever 2
Although the brake shoe 30 is attached to the brake shoe 210a acting as a secondary shoe when the vehicle body moves forward, the brake shoe 210b can be attached to the brake shoe 210b acting as a primary shoe.

The electric drum brake 32 is operated by turning the same lever 230 regardless of whether the brake pedal 40 is operated or the parking pedal 42 is operated (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 configured by twisting 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 manner 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 a ball screw mechanism 254 as a motion conversion mechanism connected to an output shaft of the speed reducer 252. An input member is connected, and an output member of the ball screw mechanism 254 is connected to the main brake cable 2.
The other end of 40 is connected. Ball screw mechanism 254
Is a mechanism for converting the rotational motion of the motor 30 into a linear motion. In the figures, reference numerals 256 and 258 both denote brackets, and reference numerals 260 and 262 both denote respective brackets 256 and 258 to the backing plate 200.
Fig. 4 shows mounting bolts for mounting on the mounting surface.

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 a housing 267 as a fixing member.
Are fitted so that they cannot rotate and can move in the axial direction. Thus, the rotational movement of the male screw 264 is converted to the linear movement of the nut 266. An output shaft 268 is coaxially attached to the opposite end of the nut 266 from the male screw 264 side. Intrusion of dust into the mutually sliding portions of the male screw 264, the nut 266 and the output shaft 268 is prevented by the housing 267 and the extendable dust boot 270.

The connection between the output shaft 268 and the other end of the main brake cable 240 is performed by the following configuration. That is, a male screw 272 for cable attachment is formed at an end of the both ends of the output shaft 268 opposite to the ball screw mechanism 254, while a nut 274 for cable attachment is provided at the other end of the main brake cable 240. Are combined. The cable fixing nut 274 is screwed to the cable fixing screw 272, the rotation preventing nut 276 is screwed to the cable fixing screw 272, and the rotation preventing nut 276 is screwed to the cable fixing nut 274. By being pressed against
The loosening of the cable mounting nut 274 is prevented.

The shoe expansion actuator 250 configured as described above applies a pulling force to the main brake cable 240 when the brake pedal 40 is operated, whereby
The other end of the lever 230 is rotated in a direction away from the brake shoe 210b, and as a result, the strut 23
6, the pair of brake shoes 210a and 210b are expanded.

The electric drum brake 32 has an effective shoe contraction mechanism for contracting the pair of brake shoes 210a and 210b by overcoming the self-servo effect generated therein. In the present embodiment, the shoe contraction mechanism includes the lever 230 and the backing plate 2.
The main brake return spring 280 is stretched between 00 and 00. The main brake return spring 280 is stretched coaxially with the main brake cable 240 and has one end connected to the other end of the lever 230.
The other end is respectively engaged with a fixed portion (for example, a housing, a bracket, or the like) of the shoe extension actuator 250. Therefore, the brake pedal 40
If the shoe extension actuator 250 is returned toward the initial position when the operation 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 essential to add such a shoe contraction mechanism to the electric drum brake 32. For example, it is necessary to increase the elastic force of the existing adjuster spring 214 and the shoe return springs 215a and 215b. It is possible to achieve the same purpose by:

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 operated by the operation force of the parking pedal 42, and the parking control 284
To the pair of brake shoes 210a, 210b
Is applied in a direction in which the lever 230 rotates in a direction in which the lever 230 expands (hereinafter, simply referred to as a “shoe expansion direction”).

As shown in FIG. 3, when the brake pedal 40 is operated, the shoe expansion actuator 250
A pulling force is applied only to the main brake cable 240, and the lever 230 is rotated in the shoe extension direction. At this time, the parking brake cable 242 is bent. 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 extension direction. At this time, the main brake cable 240 is bent. As described above, since the two cables 240 and 242 connected to the same lever 230 and operated at different times can be deformed together, the operation of one cable is not hindered by the other cable.

As is apparent from the above description, in the present embodiment, the driving force of the motor 30 is applied to the lever 230.
Since the power is transmitted via the deformable main brake cable 240, the main brake cable 2
Slip, that is, friction does not occur in the contact portion between the lever 40 and the lever 40, and as a result, wear of the contact portion between the main brake cable 240 and the lever 230 is suppressed.

Further, according to the present embodiment, the motor 30
The main brake cable 240 and the lever 230
Since no slippage occurs at the contact portions between the contact portions, the foreign matter hardly enters the contact portions.

Furthermore, according to this embodiment, since the main brake cable 240 connecting the lever 230 and the shoe expansion actuator 250 to each other is flexible, the lever 230 of the shoe expansion actuator 250
Can be changed relatively freely, so that the degree of freedom in 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. As a result, the size, weight and cost of the electric drum brake 32 can be easily reduced.

Further, in the present embodiment, since both the main brake cable 240 and the parking brake cable 240 connected to the same lever 230 are flexible, the parking brake cable 242 flexes and the lever 230 The rotation of the lever 230 is not hindered, and the main brake cable 240 is bent during the parking brake operation, so that the rotation of the lever 230 is not hindered. Therefore, any brake operation can be performed without any trouble 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 to the lever 230 and the force in the opposite direction can be transmitted. When the parking brake is operated, a force acts on the shoe expansion actuator 250 from the lever 230. On the other hand, the shoe extension actuator 250
, The reduction gear 252 and the ball screw mechanism 254
Exerts a boosting action on the force from the motor 30 (input side) to the output shaft 268 (output side), while exerts a force transmission suppressing action on the force from the output side to the input side. Will be. Therefore, in order to operate the lever 230 to which the shoe expansion actuator 250 is connected toward the operation position, the lever 230 causes the shoe expansion actuator 250 to operate it toward the operation position under the force transmission suppressing action. Must be applied, and 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 bends, so that the operation of the lever 230 to the operation position is not hindered by the force transmission suppressing operation. Is increased for the main brake and the parking brake, thereby preventing an increase in the operating force of the parking pedal 42.

That is, in the present embodiment, the brake pedal 40 constitutes an example of a “brake operating member”,
Further, the lever 230 forms an example of a “rotating member”, the ball screw mechanism 254 and the main brake cable 240 cooperate with each other to form an example of a “force transmitting mechanism”,
The main brake cable 240 constitutes an example of the “relay member”. In addition, the parking pedal 42 constitutes an example of a “second brake operating member”, the parking control 284 and the parking brake cable 242 cooperate with each other to constitute an example of a “force applying mechanism”. The cable 242 forms an example of the “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
Computer 300 including CPU, ROM and RAM
Is mainly composed. Several sensors and switches are connected to the input side of the controller 50. Some of the sensors and switches include an operating force sensor 302, a brake pedal switch 304, an accelerator pedal switch 306, a steering angle sensor 308, a vehicle deceleration sensor 310, a vehicle speed sensor 312, four wheel speed sensors 314, and a motor current. There is a sensor 316.

The operation force sensor 302 is connected to the brake pedal 4
An operation force F of 0 is detected, and a signal defining the magnitude is output. 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 outputs an ON signal (second signal) when operated. Accelerator pedal switch 306
Is an example of an acceleration operation sensor, and the accelerator pedal 44
OFF signal (first signal) when not operating, and O signal when operating
An N signal (second signal) is output. The steering angle sensor 308 is
It is an example of a turning sensor, and detects a rotation operation angle θ of the steering wheel 46 and outputs a signal defining the magnitude. The vehicle body deceleration sensor 310 detects a deceleration G in the front-rear direction of the vehicle body and outputs a signal defining the height. Vehicle speed sensor 312 detects vehicle speed V and outputs a signal defining the magnitude. 4 wheel speed sensors 3
14 respectively provided on four wheels to detect the wheel speed V _W of each wheel and outputs a signal for defining the size. 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 supply via the driver 322. And outputs a signal defining the actual supply current value I. 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. Brake pedal 4
0, the controller 50 sends the driver 3
22 is supplied with a command, and the driver 32
2 transfers current from the battery 320 to each of the electric brakes 22,
32 motors 20 and 30. Controller 50
Further, on the output side, an engine output control device (not shown) of the engine 10 (throttle control device, fuel supply control device, ignition timing control device, etc.) and a shift control device (not shown) of the A / T 12 (including a shift solenoid, etc.) And are connected. When driving the vehicle, 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 drive wheels.
That is, the controller 50 also performs traction control.

The ROM of the computer 300 stores several routines including a brake control routine and a friction material μ estimation routine. The brake control routine is shown in the flowchart of FIG. 5, and the friction material μ estimation routine is shown in the flowchart of FIG. Further, the ROM contains F-
Data representing the T characteristic by a table, a function expression, and the like;
Some data including data representing the T characteristic by a table, a function expression, and the like are also stored.

The FT characteristic shows the relationship between the operation 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 by a graph in FIG. On the other hand, the IT characteristics correspond to the motors 20 and 3.
FIG. 8 shows the relationship (obtained experimentally or by calculation) between the supply current value I to 0 and the braking torque value T applied to each wheel by the brakes 22 and 32, and is shown by a graph in FIG. I have. Considering that the FT characteristic and the IT characteristic are generally not common before and after,
The information is stored in the ROM in association with the front wheel and the rear wheel.

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. Hereinafter, it is simply associated with a plurality of discrete values of “friction material μ”). Here, the “friction material” includes a pair of brake pads 106 a and 106 b of the electric disc brake 22 for the front wheels and a pair of brake linings 216 of the electric drum brake 32 for the rear wheels.
a, 216b, and the same applies hereinafter.

Hereinafter, the brake control and the estimation of the friction material μ by the controller 50 will be described.

FIG. 9 shows the controller 50, the motors 20, 30 and the friction material 300 in this electric brake device.
The relationship between the wheel and the wheel 302 is conceptually shown. An operation force F of the brake pedal 40 is supplied to the controller 50 as operation information from the driver, and the controller 50 supplies a current value I to the motors 20 and 30 according to the operation force F. The motors 20 and 30 supply a driving force D to the friction material 300 according to the supplied current value I. Friction material 300
Gives a braking torque T to the wheels 302 with the supplied driving force D below its actual friction coefficient μ. Wheel 3
By braking torque T is applied to 02, together with the deceleration G is generated in the vehicle body deceleration G _W is generated in the wheel 302.

In this brake control, the brake pedal
Based on the operating force F of the dull 40, the motors 20 and 30 are supplied.
The supply current value I is determined, and based on the operation force F, FT
Target braking torque value T according to characteristics^*Is determined for each wheel
And the target braking torque value T for each wheel ^*Based on the IT characteristics
, The supply current value I is determined for each wheel.

On the other hand, in the friction material μ estimation,
At the time of non-brake operation, not at the time of acceleration operation, at the time of straight traveling of the vehicle, not at the time of running on a rough road, not at the time of low speed running, and not at the time of A / T12 shift. When the motors 20 and 30 are driven, the brakes 22 and 32 are operated. Further, the supply current value I of the motors 20 and 30 and the vehicle body deceleration G
Are obtained, and the actual braking torque value T of each wheel is obtained based on the vehicle body deceleration G. Further, among the plurality of types of the IT characteristic patterns, the one corresponding to the combination of the obtained actual braking torque value T and the supply current value I is selected as the current IT characteristic pattern, and the selected IT characteristic pattern is selected. The friction material μ corresponding to the IT characteristic pattern is estimated as the actual friction material μ. The friction material μ estimated value is R
Stored in AM.

The friction material μ should be originally estimated for each wheel, but in the present embodiment, the friction material μ is different between the front and rear wheels, but is substantially equal between the left and right wheels. μ is estimated independently for the front and rear wheels,
The left and right wheels are commonly estimated.

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

Next, the brake control and the estimation of the friction material μ will be described in detail with reference to the flowcharts of FIGS.

The brake control routine shown in FIG. 5 is started when the ignition switch of the vehicle is turned on, and is first executed in step S1 (hereinafter simply referred to as "S1").
The same applies to other steps. In), the operation force F is detected by the operation force sensor 302. Next, S
In 2, it is determined whether or not the current estimated value of the friction material μ exists in the RAM. If there is, the determination is YES,
In S3, the current estimated value of the friction material μ is read from the RAM, and is set as the current use value of the friction material μ. On the other hand, if there is no friction material μ, the determination is NO. It is determined whether the estimated value exists in the RAM. If there is, the determination is YES, and in S5, the previous estimated value of the friction material μ is read from the RAM,
The value is used as the friction material μ this time. On the other hand, if it does not exist, the determination is NO. In S6, the standard value of the friction material μ is read from the ROM, and is set as the friction material μ current use value. You.

In any case, in step S7, the current IT characteristic pattern is selected. A pattern corresponding to the current use value of the friction material μ is selected as the current IT characteristic pattern from the plurality of types of IT characteristic patterns. 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 to be supplied to the motors 20, 30 is set for each wheel in accordance with the selected current IT characteristic pattern. Is determined. Subsequently, in S10, a current is supplied to the motors 20, 30 at the determined target supply current values I ^* . This completes one execution of this routine, and returns to S
Return to 1.

On the other hand, the friction material μ estimation routine of FIG. 6 is also started to execute when the ignition switch of the vehicle is turned ON. First, in S11, initial setting is performed, and thereby the μ of the RAM is set. The estimation flag is set to 0. The μ estimation flag is 0 and the friction material μ
Indicates that the friction material μ has been estimated once during one running of the vehicle.

Next, in S12 to S18, it is determined whether various conditions are satisfied. Specifically, in S12,
It is determined whether the μ estimation flag is 0 or not. 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, the accelerator pedal switch 3
It is determined whether or not an acceleration operation is being performed based on whether or not 06 is ON. In S15, the steering angle sensor 308
It is determined whether or not the vehicle is turning, based on whether or not the rotation operation angle θ of the steering wheel 46 detected by the above is not 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, the wheel speed sensor 314
Is obtained by differentiating substantially time the detected wheel speed V _W by. 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, the A / T 12 sends the controller 5
Based on the signal supplied to 0, it is determined whether or not the A / T 12 is shifting (in a transient state). If the determinations in S12 and S13 are both YES, and the determinations in S14 to S18 are both NO, the process proceeds to S19 and subsequent steps, but otherwise returns immediately to S12.

In S19, the left and right front wheel brakes 2
By supplying the current to the second motor 20 at the set current value I ₀ at the same time for the set time Δt, the left and right front wheel brakes 22 are operated. In S20, during the operation, the actual current value I supplied to the motor 20 is detected by the motor current sensor 316. In S21, the vehicle body deceleration G is detected by the vehicle body deceleration sensor 310 during the operation. Then, in S22, the friction material μ of the brakes 22 of the left and right front wheels is determined from the actual supply current value I and the vehicle deceleration G.
Is estimated. 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 among the plurality of types of IT characteristic patterns are obtained. I- corresponding to the combination with
The friction material μ corresponding to the T characteristic pattern is used as the current estimated value of the friction material μ of the brakes 22 of the left and right front wheels. S23-S
In 26, the same contents as in S19 to S22 are executed for the brakes 32 of the left and right rear wheels. 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. Then, the process returns to S12. Thereafter, if S12 is executed, the μ estimation flag becomes 1
Therefore, after that, until the current vehicle traveling ends, S
When the determination of No. 12 is continued as NO, S19 to
The friction material μ estimation in S26 is omitted.

That is, in the present embodiment, the friction material μ estimation is performed only once at the time of the first non-braking operation during one running of the vehicle, and until the running of the vehicle is completed.
The estimated value of the friction material μ is not updated. However, it is of course possible to carry out the present invention in an updated manner.

FIG. 10 is a graph showing how the brakes 22, 32 are operated during the non-braking operation, whereby the vehicle speed V is temporally reduced.

If the above-mentioned friction material μ estimation start condition is satisfied at the time t ₁ , a current is supplied to the motor 20 of the left and right front wheel brakes 22 at the set current value I ₀ , thereby operating the left and right front wheel brakes 22. Is started. As a result, the vehicle speed V
However, the gradient at this time, that is, the vehicle deceleration G depends on the friction material μ of the brakes 22 of the left and right front wheels, and the friction material μ
When the frictional material μ is low, a high vehicle body deceleration G ₁ occurs, and when the friction material μ is low, a low vehicle body deceleration G ₂ occurs. 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, a time t ₃ when a short time has passed.
, A current is supplied to the motor 30 of the left and right rear wheel brakes 32 at the set current value I ₀ , whereby the operation of the left and right rear wheel brakes 32 is started. As a result, the vehicle speed V decreases as in the above case, but the gradient at this time, that is, the vehicle body deceleration G depends on the friction material μ of the brakes 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 the friction material μ is low, a low vehicle body deceleration G ₄ is generated. If the timing t ₃ to time t ₄ has passed the set time Delta] t, the motor 30 is restored to the initial state with the current supply to the motor 30 is caused to stop.

Next, an electric drum brake according to a second embodiment of the present invention will be described. However, since the present embodiment has many elements common to the 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 an electric drum brake according to the present embodiment. In the present embodiment, an operating 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 a computer 404
Is mainly composed. This controller 402
Is connected to the driver 3 to which the battery 320 is connected.
22, the electric disc brakes 22 for the left and right front wheels
The ultrasonic motor 408 is connected to the DC motor 410 of the electric drum brake 32 for the left and right rear wheels. The controller 402 uses the fact that the ultrasonic motor 408 generates a sufficiently large self-holding torque when the ultrasonic motor 408 is in the OFF state.
08 to turn on the electric disc brake brake 22 and then turn the ultrasonic motor 408 on in the operating state.
FF is set and the vehicle is kept stopped. In this embodiment, an emergency brake pedal 412 (an example of an emergency brake operation member) is provided as an operation member. Motor 4
In case of emergency when the vehicle braking by 08,410 becomes defective,
The electric drum brake 32 is mechanically operated by the operation force of the emergency brake pedal 412. The emergency brake pedal 412 is connected to the lever 230 via the emergency brake control 414 and the emergency brake cable 416. The emergency brake controller 414 and the emergency brake cable 416
Is the same as the parking control 284 and the parking brake cable 242 in the previous embodiment.

The ROM of the computer 404 contains FIG.
Stores a brake control routine represented by a flowchart. This routine is started when the ignition switch of the vehicle is turned on. First, in S401, the brake pedal switch 304 is turned on.
Is ON or not, it is determined whether or not the main brake is being operated. Assuming that the main brake operation is not being performed this time, the determination is NO, and in S402, the parking brake operation start time is determined based on whether or not the output signal of the parking pedal switch 400 changes from OFF to ON. Is determined. Assuming that this time is not the start, the determination is NO and S403
In the above, it is determined whether or not the parking brake operation is completed based on whether or not the output signal of the parking pedal switch 400 changes from ON to OFF. Assuming that this time is not the end time, the determination is NO and the process returns to S401.

Assuming that this time is the time of the main brake operation, the determination in S401 becomes YES, and in S404, the operation force F of the brake pedal 40 is detected by the operation force sensor 302. Next, in S405, the detection is performed. Electric current is supplied to the ultrasonic motor 408 and the DC motor 410 based on the operating force F thus operated, so that the electric disc brake 22 and the electric drum brake 32 are operated. As a result, the vehicle is braked. afterwards,
It returns to S401.

On the other hand, if it is assumed that the parking brake operation is started and not the main brake operation this time, the determination in S401 is NO and the determination in S402 is YE
S, and in S406, the ultrasonic motor 408
N, the electric disc brake 22 is activated, and after a certain period of time, in S407, the ultrasonic motor 40
8 is turned off at that position. As a result, 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. Then, the process returns to S401.

Assuming that this time is when the parking brake operation is completed and not when the main brake is operated,
The determination in S401 is NO, the determination in S402 is also NO, S40
The determination at 3 is YES, and in S408, a signal for returning the ultrasonic motor 408 to the original position is output to the ultrasonic motor 408. Subsequently, in S409, the ultrasonic motor 408 is turned off. Then, the process returns to S401.

Next, an electric drum brake according to a third embodiment of the present invention will be described. This electric drum brake is provided in the electric brake device, and the software configuration of the electric brake device is common to the first embodiment. In addition, since the basic configuration of the electric drum brake is common to 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 described. This will be described in detail.

As shown in FIG. 13, the electric drum brake 450 according to the present embodiment has a configuration in which the strut 236 is replaced with a drive mechanism 452 with respect to the electric drum brake 32.

The drive mechanism 452 drives the brake shoe 210b (primary shoe) by a lever 230 (main lever) as a rotating member, similarly to the strut 236. 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 the rotation stroke to the brake shoe 210b.

The drive mechanism 452 has an input member 460 interlocking with the lever 230 at a position corresponding to the strut 236. The input member 460 has a rod shape and is arranged in a design reference plane which 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 is different from the strut 236 in that a large axial gap is left between the input member 460 and the brake shoe 210b as shown in FIG. 210b. 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 46 pivotally connected to the anchor pin 206 as shown in FIG.
2 (intermediate lever). The lever 462 also has a rod shape and is arranged in the design reference plane. As shown in FIG. 14, the lever 462 is penetrated through a through hole 464 formed in the axial center of the input member 460, and the lever 462 is moved in the axial direction of the input member 460 so as to approach the brake shoe 210b. At 462, the free end (tip) is transmitted as a rotation in a direction approaching the brake shoe 210b.

The drive mechanism 452 further includes an output member 46 interlocked with the brake shoe 210b as shown in FIG.
8 substantially parallel to the input member 460 and the input member 4
The lever 60 is provided at a position on the opposite side of the pivot center point of the lever 462. The output member 468 also has a rod shape,
It is arranged in the design reference plane. As a result, 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
Both ends are supported by the tip of the lever 462 and the web 222 of the brake shoe 210b, respectively. The output member 468 and the lever 462 are rotatably connected by a pin 470. FIG. 15 (B in FIG. 13)
-B sectional view) shows the output member 468 in an enlarged manner.

As shown in FIG. 13, the drive mechanism 452 further includes a return spring 472 which constantly biases the lever 462 in a direction in which the tip of the lever 462 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 expansion actuator 250 driven by the motor 30 is operated, the lever 2 is driven.
When the 30 is rotated in a direction approaching the brake shoe 210b, the input member 460 is linearly moved in a direction (rightward in the figure) in a direction approaching the brake shoe 210b accordingly. With this linear motion, the lever 462 is rotated in a direction to approach the brake shoe 210b,
This rotation causes the output member 468 to move the brake shoe 210
b, so that the brake lining 216 fixed to the brake shoe 210b is rotated.
b is pressed against the friction surface of the drum 204. The connection point between the lever 462 and the output member 468 is determined by the lever 462 and the input member 4.
The lever 462 is located farther from the pivot support point of the lever 462 than the connection point with the lever 60. Therefore, lever 2
The rotation stroke of 30, ie, 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 expanding mechanism.

During non-braking operation, there is a relatively large initial clearance between the brake lining 216b and the drum 204. In the present embodiment, the rotation stroke of the lever 230 is enlarged and the brake shoe 2
10b. Therefore, according to the present 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 initial clearance has disappeared, that is, in a region where the apparent rigidity is high when the brake shoe 210b is operated, the rotation stroke of the lever 230 is enlarged and transmitted to the brake shoe 210b. Therefore, according to the present embodiment, the rotation stroke of the lever 230 required to generate the same stroke on the brake shoe 210b is reduced, and the rotation of the lever 230 required to generate the same frictional force on the brake lining 216b is performed. The dynamic stroke is also reduced, and as a result, the operation responsiveness of the electric drum brake 450 is improved.

As the brake linings 216a, 216b wear, the pivoting 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, the brake lining 216
Even if a and 216b are worn, the maximum rotation angle of the motor 30 does not need to be so large, and it becomes easy to control the driving force of the motor 30 with stable accuracy over the entire range of change of the rotation angle of the motor 30.

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

In the drive mechanism 452 in the third embodiment, as shown in FIG. 14, the rotation plane of the lever 462 (the locus drawn by the rotation of the lever 462) and the rotation plane of the web 222 of the brake shoe 210b are formed. While they exactly coincide with each other, the pivot plane of the lever 230 and the lever 46
4 do not exactly coincide with each other. Therefore, when the electric drum brake 450 operates, the input member 4
A moment is generated at 60. On the other hand, in the present embodiment, as shown in FIG.
The driving mechanism 502 is configured such that both ends of the input member 504 are associated with such a lever 500 and the lever 462 and the brake shoe 210b. Configuration. Accordingly, in the present embodiment, not only the turning plane of the lever 462 and the turning plane of the web 222 of the brake shoe 210b exactly coincide with each other, but also the turning plane of the lever 500 and the turning plane of the lever 462. And exactly match each other. Therefore, according to the present embodiment, a moment does not need to be generated in the input member 504 when the electric drum brake operates.

Although the embodiments of the present invention have been described in detail with reference to the drawings, various modifications and changes may be made based on the knowledge of those skilled in the art without departing from the scope of the claims. It goes without saying that the present invention can be implemented in an improved form.

[Brief description of the drawings]

FIG. 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;

FIG. 3 is an enlarged side sectional view showing the electric drum brake in FIG. 1;

FIG. 4 is an enlarged partial cross-sectional side view showing the shoe expansion actuator in FIG. 3;

FIG. 5 is a flowchart showing a brake control routine stored in a ROM of the computer shown in FIG.

FIG. 6 is a flowchart showing a friction material μ estimation routine stored in the ROM.

FIG. 7 is a graph showing FT characteristics in the embodiment.

FIG. 8 is a graph showing an IT characteristic in the embodiment.

FIG. 9 is a system diagram conceptually showing the configuration of the embodiment.

FIG. 10 is a graph showing a state in which the vehicle speed V is reduced by the operation of the brake during the non-brake operation in the embodiment.

FIG. 11 is a system diagram showing an overall configuration of an electric brake device including an electric drum brake according to a second embodiment of the present invention.

12 is a flowchart illustrating a brake control routine stored in a ROM of a computer of the controller in FIG. 11;

FIG. 13 is a side view showing an electric drum brake according to a third embodiment of the present invention.

FIG. 14 is a sectional view taken along the line AA in FIG.

FIG. 15 is a sectional view taken along line BB in FIG.

FIG. 16 is a sectional view showing a drive mechanism of an electric drum brake according to a fourth embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 30 motor 32,504 electric drum brake 40 brake pedal 42 parking pedal 50,402 controller 204 drum 210a, 210b brake shoe 216a, 216b brake lining 230,500 lever 284 parking control 320 battery 240 main brake cable 242 parking brake cable 408 super Sound wave motor 410 DC motor 412 Emergency brake pedal 414 Emergency brake control 416 Emergency brake cable 452,502 Drive mechanism 460,504 Input member 462 Lever 468 Output member

Claims (5)

[Claims] A rotating member having a friction surface and rotating with a wheel; a friction member pressed against the friction surface to suppress rotation of the rotating member; and a power member driven by electric power based on an operation of a brake operation member. An electric brake including: a motor that rotates; a rotating member that presses the friction material against the friction surface by rotation; and a force transmission mechanism that transmits a driving force of the motor to the rotating member. An electric brake having a structure for transmitting a driving force of the motor to the rotating member via a flexible relay member. 2. The device according to claim 1, wherein the force transmitting mechanism transmits the driving force of the motor to the rotating member as a tensile force, and the relay member is formed of a flexible wire. Electric brake. 3. A force applying mechanism for applying a second pulling force to the rotating member via a second relay member made of a flexible wire, based on an operation of a second brake operating member. The electric brake according to claim 1 or 2, further comprising: 4. The electric brake according to claim 1, wherein said electric brake includes a drum and a brake lining, each of which includes the rotating body and the friction material, and the brake lining is fixed to a brake shoe. 4. A drive mechanism for driving the brake shoe by turning, the drive mechanism extending the turning stroke of a turning member and transmitting the enlarged stroke to the brake shoe.
The electric brake according to any one of the above. 5. The driving mechanism according to claim 1, wherein (a) an input member interlocked with the rotating member, (b) an output member interlocked with the brake shoe, and (c) an output member interlocked with the output member. 5. The electric brake according to claim 4, further comprising: transmitting an operation stroke obtained by enlarging the operation stroke of the input member to the output member.