JPH11171004A - Brake and brake system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable quantities related to the braking force of a wheel to be detected with sufficient reliability and durability on a brake which allows the detection of such quantities. SOLUTION: With a disc brake 22, a force switch 150 is installed between an inner pad 106b and a receiving section 110b which receives the inner pad 106b to restrain it from turning jointly with a disc, and further the force switch 150 is made to receive a force applied from the inner pad 106b and set so that depending on whether or not the force received is equal to or more than a prescribed value which is of other figures than zero, it emits signals varying in two conditions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake for a vehicle, and more particularly to a technique for detecting an amount related to a braking force of a wheel in a brake.

[0002]

2. Description of the Related Art PCT International Publication Specification WO 97/038.
69 describes a conventional example of a brake for a vehicle. In this brake, a brake-related amount, which is an amount related to the wheel braking force by the brake, is measured by a sensor such as a resistance wire strain gauge or a piezoelectric sensor. Detected as a continuous value.

[0003]

However, since the brake-related variable to be detected by the sensor has a large variation range, the sensor accurately determines the brake-related variable over the entire variation range. It is difficult to detect. In addition, the environment in which the sensor is placed is severe for the sensor such that the temperature rises sharply, foreign substances such as mud, water, and dust easily enter, and the vibration is severe. Therefore, the conventional brake has a problem that it is difficult to detect a brake-related amount with sufficient reliability and durability.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a brake and a brake system capable of detecting a brake-related quantity with sufficient reliability and durability. It is in.

[0005] This problem is solved by the following aspects.
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 that rotates together with a wheel, a friction material that is brought into contact with the rotating body to suppress rotation of the wheel, and that the friction material does not rotate along with the rotating body in the contact state. A receiving member for receiving the friction material, a pressing device for pressing the friction material to contact the rotating body, and a force provided between the friction material and the receiving member for receiving the force from the friction material and receiving the force. And a force switch for outputting a signal that changes between two states according to whether or not is greater than or equal to a non-zero set value. The force switch is different from a sensor in that a physical quantity cannot be continuously detected like a general switch. However, like a general switch, it is not as affected by an external environment as a sensor because of its relatively simple structure and detection principle. For example, in the case of a force switch, the correspondence between the actual magnitude of the physical quantity and the signal output by the force switch when it is detected is not as affected by the external environment as in the case of the sensor. . Therefore,
According to this brake, the force acting on the receiving member from the friction material as the brake-related amount can be detected with sufficient reliability and durability. (2) The rotating body is a disk having a friction surface on its surface, the friction material is a brake pad that is brought into contact with the friction surface of the disk, and the force switch is a brake pad and the receiving member. The brake according to claim 1, wherein the brake pad is provided at a position between the two positions, and the clearance decreases as the amount of rotation of the brake pad increases. (3) The brake according to (1) or (2), wherein a plurality of the force switches are provided so that the set values are different from each other.
According to this brake, the brake-related amount can be continuously detected as compared with the case where only one force switch is provided. (4) The force switch is a pair of contacts that can be relatively displaced between a connection position and a cutoff position, one including the friction material, and the other including one attached to the receiving member (1) to ( The brake according to any of the above 3). According to this brake, the structure and detection principle of the force switch can be easily simplified, and thus the reliability and durability of the force switch can be easily improved. (5) The brake according to item (4), wherein the one attached to the friction material among the pair of contacts is a movable contact, and the one attached to the receiving member is a fixed contact. (6) The brake according to any one of (1) to (5), wherein the pressing device uses a motor as a drive source without using fluid pressure. (7) The pressing device uses a fluid pressure (1).
Or the brake according to any one of (5) to (5). (8) The brake described in any of (1) to (7),
A brake operation related information estimating device for estimating information related to the operation of the brake based on a signal of the force sensor. In this brake system, "information related to brake operation"
For example, there are a friction coefficient of a friction material, whether or not a fade has occurred in a brake, whether or not a brake is abnormal, a road surface friction coefficient, and the like. (9) The brake according to any one of (1) to (7), further including a signal that continuously changes in accordance with an amount related to a pressing force with which the pressing device presses the friction material. A sensor having a pressing force related amount sensor for outputting, and estimating a friction coefficient of the friction material based on a relationship between the signal output from the pressing force related amount sensor when the signal of the force switch changes and the set value. A brake system for estimating a friction coefficient of a friction material. According to this brake system, the friction coefficient of the friction material can be estimated. If the friction coefficient of the friction material can be estimated, highly accurate brake control can be performed by using the estimation result. (10) the pressing device includes a pressing member that presses the friction material by engaging the friction material from a side opposite to the rotating body side,
The brake system according to claim 9, wherein the pressing force-related amount sensor includes a pressing force sensor provided on the pressing member and receiving the axial force of the pressing member to detect the axial force as a continuous value. (11) The brake according to (9), wherein the pressing device includes a motor that presses the friction material, and the pressing force related amount sensor includes a motor power sensor that detects a power value of the motor as a continuous value. system. (12) The brake system according to (11), wherein the motor power sensor includes a motor current sensor that detects a current value of the motor as a continuous value. (13) When the force switch receives a force from the friction material that increases from a value smaller than the set value and reaches a set value, the signal changes from OFF to ON and from ON to OFF. One is performed, and when the set value is decreased from a value larger than the set value and reaches the set value, the other is performed, and the friction material friction coefficient estimating apparatus changes the signal of the force switch from OFF to ON. (9) through (1) in which the friction coefficient of the friction material is estimated in response to at least one of the change of the friction material and the change from ON to OFF.
The brake system according to any of the above 2). (14) The frictional material friction coefficient estimating device calculates the frictional coefficient of the frictional material according to the change of the signal of the force switch from OFF to ON and the change from ON to OFF. The brake system according to the mode (13), wherein the estimation is performed. According to this brake system, the force switch signal changes from OFF to ON and from ON to OFF.
In comparison with the case where the friction coefficient of the friction material is estimated in response to only one of the changes to be performed, more friction coefficient information can be obtained, so that the estimation accuracy of the friction coefficient can be easily improved. obtain. (15) The friction material friction coefficient estimating device, by dividing the set value by the pressing force related amount detected by the pressing force related amount sensor when the signal of the force switch changes,
The friction coefficient of the friction material is estimated (9) or
The brake system according to any one of the above (14). (16) Further, when the friction coefficient estimated by the friction material friction coefficient estimating device is lower than a reference value, the friction material includes a brake fade determination device that determines that a fade has occurred (9) to ( 15) The brake system according to any one of the above items. (17) The brake according to any one of (1) to (7), wherein the physical quantity related to the operation of the brake is other than the force received by the force switch, and the brake is abnormal. And a sensor that detects a change in the relationship between the force received by the force switch and whether the brake is abnormal based on the relationship between the signal of the sensor and the signal of the force switch. A brake abnormality check device for checking whether or not the brake system is operating. (18) The brake described in any of (1) to (7),
A road surface friction coefficient estimating device for estimating a friction coefficient of a road surface on which the vehicle is traveling based on a signal of the force switch. (19) the brake, (a) an electric brake that electrically brakes the wheels by pressing the friction material without using a fluid pressure using a motor as a drive source, and (b) driving a brake operating member. A manual brake that mechanically brakes the wheels by pressing the friction material as a source, and (c) provided between the manual brake and the brake operating member. The brake system according to any one of (1) to (18), including a manual brake control device that permits operation and prohibits normal operation. In this brake system, an electric brake is provided as a service brake, and a manual brake that brakes wheels with a friction material using a brake operating member as a driving source is provided as an emergency brake. That is, this brake system is provided with an electric brake system mainly including a brake operation member and an electric brake, and a manual brake system mainly including a brake operation member, a manual brake control device, and a manual brake. Therefore, according to this brake system, when the electric brake fails, the driver can manually brake the vehicle by generating a braking force of a magnitude corresponding to the operation force on the wheels, and as a result, the brake system can withstand failure. The performance is improved. In this brake system, the “manual brake” and the “manual brake control device” may be of a type that does not use a fluid pressure or a type that uses a fluid pressure. In the brake system, the “operation information” includes, for example, information indicating the magnitude of the operation force of the brake operation member and information indicating the length of the operation stroke. In this brake system, the "friction material" and the "rotary body" can be provided separately for the electric brake and the manual brake, or can be provided in common for both. (20) Further, a brake operation related information estimating device for estimating information related to the operation of the brake based on a signal of the force switch, wherein the information estimation is prohibited when the manual brake control device is operated. Including (1
Brake system according to item 9). In this brake system, "information related to the operation of the brake"
It can be interpreted in the same way as in paragraph (8). (21) The brake according to any one of (1) to (7), further comprising: a braking force applied to the wheel by the brake or a pressing force by which the pressing device presses the friction material. A brake-related quantity sensor that outputs a signal that continuously changes in accordance with a brake-related quantity, and a predetermined value between the output signal and the wheel braking force based on the output signal of the brake-related quantity sensor. A wheel braking force estimating device that estimates a wheel braking force according to the relationship, wherein the device corrects the relationship based on a signal output from the brake-related amount sensor when a signal of the force switch changes. A brake system (claim 4). As is clear from the above description, when the force switch and the brake-related quantity sensor are compared with each other, the force switch has the advantage of being highly reliable, but has the disadvantage that continuous detection is impossible. On the other hand, the brake-related quantity sensor has an advantage that continuous detection is possible, but has a disadvantage that reliability is low. In this way, the force switch and the brake-related quantity sensor have a relationship in which one disadvantage is an advantage of the other. Thus, if the disadvantages of the brake-related quantity sensor are compensated for by the advantages of the force switch, both improved reliability and continuous detection can be realized together. The brake system described in this section was made based on such knowledge. In this brake system, when the brake-related amount sensor is a pressing-related amount sensor that detects the amount related to the pressing force as a continuous value, the detected value is not affected by the fluctuation of the friction coefficient of the friction material. Whereas the force switch is affected. Therefore, in that case, the above-described “correction of relation” results in
This is performed in consideration of both the variation of the characteristic of the pressing force related amount sensor and the variation of the friction coefficient of the friction material. On the other hand, if the brake-related quantity sensor is a wheel braking force sensor that detects the wheel braking force as a continuous value, the brake-related quantity sensor has substantially the same physical quantity and is not affected by the fluctuation of the friction coefficient of the friction material Is detected by the wheel braking force sensor and the force sensor, so that “correction of the relationship” is performed as calibration of the wheel braking force sensor. In this brake system, the “correction of the relation” includes a form in which the relation is directly corrected and a form in which the relation is corrected as a result. The latter form includes a form in which the actual signal is corrected and the relation is not corrected. ,
There is a form in which the wheel braking force tentatively estimated based on the actual signal and the relationship is not corrected. (22) The brake system according to (21), wherein the brake-related amount sensor includes a pressing force sensor that receives the pressing force and outputs a signal that continuously changes according to the received pressing force. The pressing force sensor does not need to be placed in an environment as severe as a braking force sensor described later. Therefore, according to this brake system, the reliability and durability of the pressing force sensor can be easily improved. (23) a braking force, wherein the brake-related amount sensor receives a force to be applied to the receiving member from the friction material as the wheel braking force, and outputs a signal that continuously changes according to the received wheel braking force; The brake system according to (21), including a sensor. (24) A relationship in which the wheel braking force estimating device corrects the relationship based on a difference between an actual signal output by the brake-related amount sensor when a signal of the force switch changes and a true signal to be output. The brake system according to any one of (21) to (23), including a correction means (Claim 5). (25) The relationship correction means, despite the signal difference,
The brake system according to mode (24), wherein the relationship is corrected so that an acquired value of the pressing force based on the actual signal matches an actual value. . (26) The brake system according to any one of (21) to (25), further including a brake operation-related information estimating device that estimates information related to the operation of the brake based on the signal of the force switch. In this brake system, "information relating to the operation of the brake" and "apparatus for estimating information relating to the operation of the brake" can be interpreted in the same manner as in the above item (8). (27) The brake operation-related information estimating device estimates a friction coefficient of the friction material based on a relationship between the signal output from the brake-related amount sensor when the signal of the force switch changes and the set value. The brake system according to item (26), including a friction material friction coefficient estimation device. In this brake system, the "friction material friction coefficient estimating device"
Can be interpreted in the same way as in the section.

[0007]

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 a brake system according to a first embodiment of the present invention. This brake system comprises left and right front wheels FL, FR and left and right rear wheels RL, R
R is provided in a four-wheeled vehicle provided with R. This vehicle is
An engine 10 (internal combustion engine) as a prime mover and an automatic transmission (hereinafter abbreviated as “A / T”) 12 as a driving force transmission device are provided. And at least one of the left and right rear wheels is driven, thereby driving the vehicle.

The left and right front wheels FL and FR are provided with an electric disk brake 22 driven by an ultrasonic motor (hereinafter simply referred to as "motor") 20 and not using fluid pressure. On the other hand, the left and right rear wheels RL, RR are provided with an electric drum brake 32 that uses a DC motor (hereinafter simply referred to as “motor”) 30 as a drive source and does not use fluid pressure as a service brake, while an emergency brake is provided. As a brake pedal 3 as a brake operating member
A mechanical drum brake 36, which uses 4 as a drive source and does not use fluid pressure, is provided. An electric drum brake 32 and a mechanical drum brake 36 are provided on each of the same rear wheels. However, the brake lining as a friction material and the drum as a rotating body are respectively
The electric drum brake 32 and the mechanical drum brake 36 are provided in common.

This vehicle is provided with several members operated by the driver. Some of the operation members include the brake pedal 34 as a main brake operation member, a parking pedal 42 as a parking brake operation member, an accelerator pedal 44 as an acceleration operation member, and a steering wheel 46.

When the brake pedal 34 is operated, at least one of the electric disk brake 22, the electric drum brake 32 and the mechanical drum brake 36
The vehicle is braked. Specifically, (a) when both the electric disc brake 22 and the electric drum brake 32 are normal, the vehicle is braked by both brakes 22 and 32, and (b) the electric disc brake 22 breaks down. When the electric drum brake 32 is normal, the vehicle is braked only by the electric drum brake 32. (c) When the electric disc brake 22 is normal and the electric drum brake 32 fails, (E) When the vehicle is braked by the electric disc brake 22 and the mechanical drum brake 36, and (e) both the electric disc brake 22 and the electric drum brake 32 fail (the power supply and the electronic control unit (hereinafter referred to as “ECU”) ), The vehicle is braked only by the mechanical drum brake 36.

On the other hand, when the parking pedal 42 is operated, the vehicle is parked by the electric disc brakes 22 of the left and right front wheels FL and FR. The electric disk brake 22 stops the vehicle using the stationary holding torque of the ultrasonic motor 20. Further, when the accelerator pedal 44 is operated, the driving force of the engine 10 is increased, and the vehicle is thereby driven. Steering wheel 46
Is rotated, the steered wheels are steered by a steering device (not shown) accordingly.

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 is typically shown in a plan sectional view.

The electric disk brake 22 includes a mounting bracket 100 as a fixing member attached to a vehicle body (not shown), and a disk 104 having friction surfaces 102 on both sides and rotating with wheels.
The mounting bracket 100 supports the pair of brake pads 106a and 106b movably along the rotation axis of the disk 104 at positions sandwiching the disk 104 from both sides. Also, the mounting bracket 10
0 indicates that each brake pad 1
Receiving portion 11 that receives frictional force generated in 06a and 106b
0a and 110b. In the figure, the arrow X indicates the direction in which the disk 104 rotates when the vehicle body moves forward.

A pair of brake pads 106a, 106b
Of these, the one outside the vehicle body (right side in the figure) is the outer pad 106a, and the one inside the vehicle body (left side in the figure) is the inner pad 106b. Outer pad 106a
When it comes into contact with the disk 104 and rotates with it, it comes into contact with the receiving portion 110a at the end in the traveling direction, and further rotation of the outer pad 106a is prevented. Similarly, when the inner pad 106b comes into contact with the disk 104 and rotates with the disk 104, the inner pad 106b abuts on the receiving portion 110b at the end on the traveling direction side, and further rotation of the inner pad 106b is prevented.

The electric disk brake 22 is further movable in the rotation axis direction of the disk 104.
A caliper 120 that is immovable in the rotation direction of 04 is provided. The caliper 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. Caliper 12
0 straddles the disk 104 and a pair of brake pads 1
06a and 106b are attached to the vehicle body in a posture of sandwiching them from behind. The caliper 120 includes (a) the outer pad 10
A reaction portion 126 that engages from behind with 6a, (b)
A pressing portion 128 for pressing the inner pad 106b from behind, (c) the reaction portion 126 and the pressing portion 1
28 and a connecting portion 130 that connects the two with 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 behind the inner pad 106b so that the pressing member 134 cannot rotate around the axis of the pressing member 134 and can move in the axial direction. Therefore, when the rotation shaft 136 of the motor 20 rotates, the rotational motion is converted by the ball screw mechanism 132 into a linear motion of the pressing member 134. By the movement of the pressing member 134, a pressing force is applied to the inner pad 106b and the outer pad 106a, whereby the pair of brake pads 106a, 1
06b is pressed against the disk 104. By the pressing, a frictional force is generated between each of the brake pads 106a and 106b and the disk 104, and the wheels are braked.

That is, in this embodiment, the disk 104 constitutes a "rotating member", the pair of brake pads 106a and 106b constitute a "friction material", and the pair of receiving portions 110a and 110b constitute a "receiving member". And the motor 20, the ball screw mechanism 132 and the pressing member 134 cooperate with each other to form a "pressing device".

A force switch 150 is provided on a receiving portion 110b of the pair of receiving portions 110a and 110b which receives the inner pad 106b. The force switch 150
As shown in an enlarged manner in FIG. 3, a movable member 152 and a disc spring 154 as an elastic member are provided. Movable member 152
Is a stepped member in which a large-diameter portion 156 and a small-diameter portion 158 both having a circular cross section are formed coaxially, and the large-diameter portion 156 is fitted in the receiving portion 110b so as to be slidable in the axial direction. , The small diameter portion 158 penetrates the disc spring 154. The disc spring 154 urges the movable member 152 in a direction approaching the inner pad 106b, but the stopper 1 is attached to the mounting bracket 100 to restrict the approach limit.
59 are formed.

A movable contact 160 is provided on the distal end surface of the small diameter portion 158.
Is provided. Correspondingly, the receiving portion 110b is provided with a fixed contact 162 with which the movable contact 160 contacts. The fixed contact 162 has elasticity. When the movable member 152 moves against the elastic force of the disc spring 154, the distal end surface of the small diameter portion 158 finally comes into contact with the receiving portion 110b. Inner pad 106
b is transmitted to the receiving portion 110b via the movable member 152.

Fixed contact 162 is connected to wire E
It is connected to one input terminal of CU50. That wire 1
64 is passed through the mounting bracket 100. The fixed contact 162 and the wire 164
Is the mounting bracket 1 by the insulator 165.
00 is electrically insulated. On the other hand, the movable contact 16
Numeral 0 is grounded by the movable member 152 and the mounting bracket 100, both of which are conductive, and the wire 166 connected to the mounting bracket 100.

The movable contact 160 is always separated from the fixed contact 162 by the elastic force of the disc spring 154. That is, the signal of the force switch 150 is always
It is F. However, if the force that the movable member 152 receives from the inner pad 106b exceeds a set value (preload of the disc spring 154), the movable member 152 resists the elastic force of the disc spring 154 together with the inner pad 106b and the inner pad 106b. 106 b moves in a direction in which it rotates with the disk 104, and the movable contact 160 comes into contact with the fixed contact 162. At this time, the signal of the force switch 150 is changed from OFF to O
N.

In this embodiment, the force switch 150 is provided on the receiving portion 110b.
10a.

FIG. 4 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 typically shown in a side view.

The electric drum brake 32 has 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. 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 210a, 210 each forming an arc shape are provided.
b is attached so as to face the inner peripheral surface of the drum 204. A pair of brake shoes 210a, 210b
Is movably attached to the backing plate 200 along its surface by shoe hold-down devices 212a and 212b.

A pair of brake shoes 210a, 210b
Are connected to each other by an adjuster 208 such that one end cannot be approached to the other and can be separated from each other, while the other end is brought into contact with the anchor pin 206, thereby rotating around each end. Supported as possible. 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 20 by the shoe return springs 215a and 215b.
It is biased toward 6. Each brake shoe 210
The brake linings 216a,
216b is held, 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 216
a, 216b and the drum 204 generate a frictional force. In addition, the adjuster 208 causes a gap between the pair of brake linings 216a and 216b and the drum 204 to be worn by a human force before the vehicle body is assembled and while the vehicle is stopped, and abrasion of the pair of brake shoes 210a and 210b while the vehicle is running. Automatically adjust according to.

Each of the brake shoes 210a, 210b is composed of a rim 220 and a web 222, and one web 22 of a pair of brake shoes 210a, 210b.
2, a lever 230 is attached so as to be rotatable in a direction intersecting the rotation axis of the drum 204. Web 22
2, a pin 232 as a lever support member is fixedly mounted, and one end of a lever 230 is rotatably connected to the pin 232. This lever 230
The struts 236 serving as a force transmitting member are provided in the notches in the portions facing each other with the brake shoe 210b.
Are engaged at both ends. The strut 236 has an adjusting function of adjusting the length of the strut 236 by a screw mechanism.
The gap between the a and 210b and the drum 204 can be adjusted by human power before the vehicle body is assembled and while the vehicle body is stopped.

The other end (free end) of the lever 230 is connected to one end of a service brake cable 240. This service brake cable 240 is configured by twisting a plurality of wires, and is flexible. The service 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. 5, 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 with a ball screw mechanism 254 as a motion conversion mechanism. The input member is connected and configured,
The other end of the service 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 a linear motion. In the figure, reference numerals 256 and 258 both indicate brackets, and reference numerals 260 and 262
Both show bolts for attaching the brackets 256 and 258 to the backing plate 200.

The ball screw mechanism 254 is constructed by screwing a nut 266 as an output member 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 service brake cable 240 is performed by the following configuration. That is, the male screw 272 for cable attachment is formed at the opposite end of the output shaft 268 from the end opposite to the ball screw mechanism 254, while the nut for cable attachment is attached to the other end of the service brake cable 240. 2
74 are attached. The cable attachment nut 274 is screwed into the cable attachment screw 272,
A non-rotating nut 276 is screwed into the male screw 272 for cable attachment, and the non-rotating nut 2
By pressing the cable 76 against 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 service brake cable 240 when the brake pedal 34 is operated, so that the lever 230 moves the other end thereof to the brake shoe 21.
0b, and as a result, a pair of brake shoes 210a,
210b is 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 is a service brake return spring 280 stretched between the lever 230 and the backing plate 200, as shown in FIG. The service brake return spring 280 is stretched coaxially with the service brake cable 240 and has one end at the other end of the lever 230 and the other end at a fixed portion of the shoe expansion actuator 250 (e.g., the housing). , Brackets, etc.).
Therefore, if the shoe expansion actuator 250 is returned toward the initial position when the operation of the brake pedal 34 is released, the lever 230 is rotated toward the initial position by the compression force of the service brake return spring 280.

Having described the electric drum brake 32, the mechanical drum brake 36 will now be described.

In the mechanical drum brake 36, the service brake cable 240 and the shoe expansion actuator 2 of the plurality of components of the electric drum brake 32 are used.
Components other than the 50 and the service brake return spring 280 are shared with the electric drum brake 32.
In the mechanical drum brake 36, the service brake cable 240, the shoe expansion actuator 250, and the service brake return spring 280 are used.
Instead, an emergency brake cable 282 and an emergency brake return spring 284 coaxial therewith are used. One end of the service brake cable 240 and one end of the emergency brake cable 282 are connected to the other end of the lever 230. As a result, even when the mechanical drum brake 36 is operated, the lever 230 rotates. By pressing the pair of brake linings 216a and 216b against the drum 204, the rotation of the wheels is suppressed. The emergency brake cable 282 is also formed by twisting a plurality of wires and is flexible. As shown in FIG. 1, the emergency brake cable 282 is guided by an outer casing 286 mounted around the vehicle body.

The emergency brake cables 282 are provided on the left rear wheel mechanical drum brake 36 and the right rear wheel mechanical drum brake 36, respectively, and the other end of the two emergency brake cables 282 is provided. Is mechanically linked to the brake pedal 34 via a manual brake control device 300, as shown in FIG.

FIG. 6 shows an enlarged view of the manual brake control device 300 and also shows a brake pedal device 302. Brake pedal device 3
02 is provided with a pedal bracket 304 fixedly mounted on the vehicle body. This pedal bracket 304
Moves the brake pedal 34 to its proximal end (rotation support point).
, Is supported so as to be rotatable around one axis extending in the left-right direction of the vehicle. While the non-operation position of the brake pedal 34 is defined by the stopper 306, the brake pedal 3
4 is urged toward the stopper 304 by the return spring 308. The brake pedal 34 is relatively rotatably engaged with a rear end (right end in the drawing) of a push rod 312 movable in the vehicle front-rear direction via a clevis 310 (an example of a rotation connection mechanism). Accordingly, the rotation of the brake pedal 34 is converted into the movement of the push rod 312.

The manual brake control device 300 includes a housing 314 fixedly mounted on a vehicle body. The housing 314 includes a first piston 316.
And the second piston 318 are fitted coaxially with each other and slidably in the vehicle longitudinal direction. First piston 316
Is disposed on the rear side of the vehicle body with respect to the second piston 318.
Both pistons 316 and 318 can move relative to each other. The front end (the left end in the figure) of the push rod 312 is engaged with the rear end (the right end in the figure) of the first piston 316. The operating force f of the brake pedal 34 is input to the first piston 316 by the push rod 312 in the direction in which the first piston 316 moves forward (to the left in the figure).
As a result, the first piston 316
Mechanically linked with A spring 3 as an elastic member is provided between the first piston 316 and the housing 314.
20 are provided. This spring 320 is
The piston 316 is constantly biased in a direction approaching the push rod 312, that is, a direction in which the brake pedal 34 moves toward the non-operation position. Therefore, if the brake pedal 34 is operated during normal operation of the electric drum brake 32, an operation stroke corresponding to the operation force f is applied to the brake pedal 34.
, The brake operation feeling is as good as in the conventional hydraulic brake system. That is, in the present embodiment, the first piston 316 and the spring 320 cooperate with each other to form the operation stroke applying mechanism 321.

The engagement protrusion 322 is provided from the first piston 316.
The (engaging portion) extends coaxially toward the second piston 318. The retracted end position of the second piston 318 is defined by the stopper 324, and the retracted end position (related to the gap between the pistons 316 and 318) is
When the brake pedal 34 is in the non-operation position (position shown), the engagement protrusion 322 does not engage with the second piston 318, and when the operation force f exceeds the reference value f ₀ , the first piston 316 Designed to engage piston 318. The reference value f ₀ is, for example, as shown in the graph of FIG. 7, in a state in which both the electric disc brake 22 and the electric drum brake 32 are normal, and a deceleration that is high enough not to occur normally, for example, 1.2 G, It can be set to the magnitude of the operation force f when generated on the vehicle body. By any chance,
The electric disc brake 22 is also the electric drum brake 3
After the operating force f exceeds the reference value f ₀ set in such a state in which the mechanical drum brake 3 is operated normally by the second piston 318, as will be described in detail later.
Since the operation of No. 6 is also performed at the same time, the gradient of the vehicle body deceleration increases as shown in the graph of FIG.

As shown in FIG. 6, the second piston 318
Are connected to the other ends of two emergency brake cables 282 for the left and right rear wheels via a lever device 326.

The lever device 326 includes a lever 328 and a lever bracket 330 fixedly mounted on the vehicle body.
And The lever bracket 330 is used for the lever 3
28 at its proximal end (fulcrum) with the second piston 3
It is supported rotatably in one plane including the 18 axes.
The lever 328 is engaged with the front end of the second piston 318 via the clevis 332 at an intermediate portion (point of force), and is constantly urged toward the second piston 318 by the return spring 334. After all, the second
The piston 318 is always urged to the retracted end position by the return spring 334. Lever 328
Are connected to the other ends of two emergency brake cables 282 for the left and right rear wheels via clevis 336. Thus, if the second piston 318 is advanced (moved to the left in the figure), the lever 328 is rotated by the second piston 318 (clockwise in the figure), and as a result, The two emergency brake cables 282 are pulled to the left in the figure and pulled out of the outer casing 286. At this time, the emergency brake cable 282 is driven with the stroke of the second piston 318 expanded by the lever 328. In the drawing, reference numeral 338 denotes an emergency brake cable 282.
10 shows a cable fixing bracket attached to the vehicle body to fix the outer casing 286 of FIG.

When the electric drum brake 32 is normal,
When the brake pedal 34 is operated, as shown in FIG. 4, a tensile force is applied to the service brake cable 240 by the shoe expansion actuator 250, whereby
The lever 230 is connected to the pair of brake shoes 210a, 210
b is rotated in the expanding direction (hereinafter simply referred to as “shoe expanding direction”). At this time, since the emergency brake cable 282 has flexibility as described above, it is bent. Therefore, in the present embodiment, the brake shoes 210a, 210
The operation of 10b is prevented from being obstructed by the manual brake control device 300.

When the electric drum brake 32 fails, if the brake pedal 34 is operated, a tensile force is applied to the emergency brake cable 282 by the brake pedal 34, whereby the lever 230 rotates in the shoe extension direction. Be moved. At this time, the service brake cable 240 is connected to the emergency brake cable 2 as described above.
Since it has flexibility like 82, it is bent. Therefore, in the present embodiment, the operation of the brake shoes 210a and 210b by the mechanical drum brake 36 is also prevented from being hindered by the electric drum brake 32.

In short, in the present embodiment, since the two cables 240 and 282 connected to the same lever 230 and operated at different times from each other can be deformed together, the operation of one cable is performed by the other cable. It is not hindered.

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

As shown in FIG. 1, the ECU 50 has a CPU
It is mainly configured by a computer 346 including 340, ROM 342, and RAM 344. This ECU
Several sensors and switches are connected to the input of 50. Some of the sensors and switches include the above-described two force switches 150 for the left and right front wheels FL and FR, an operation force sensor 348, a brake pedal switch 350, a parking pedal switch 351, an accelerator pedal switch 352, and an accelerator pedal. Operation amount sensor 3
53, a steering angle sensor 354, a yaw rate sensor 355, a longitudinal acceleration sensor 356, a lateral acceleration sensor 357, a front wheel load sensor 358, a rear wheel load sensor 359, a wheel speed sensor 360 for four wheels, and a motor rotation position sensor 362 for four wheels.
And a motor current sensor 364 for four wheels.

The operation force sensor 348 is connected to the brake pedal 3
4 is detected, and a signal defining the magnitude is output. The brake pedal switch 350 is an example of a main brake operation sensor, and outputs an OFF signal (first signal) when the brake pedal 34 is not operated, and outputs an ON signal (second signal) when operated. Parking pedal switch 3
51 is an example of a parking brake operation sensor,
When the parking pedal 42 is not operated, the OFF signal (first
Signal), and outputs an ON signal (second signal) during operation.
The accelerator pedal switch 352 is an example of an acceleration operation sensor, and outputs an OFF signal (first signal) when the accelerator pedal 44 is not operated, and outputs an ON signal (second signal) when the accelerator pedal 44 is operated. The accelerator pedal operation amount sensor 353 is an example of an acceleration operation amount sensor, and detects an operation amount of the accelerator pedal 44 and outputs a signal defining the operation amount. The steering angle sensor 354 is an example of a vehicle turning amount sensor, and detects a rotation operation angle of the steering wheel 46 and outputs a signal defining the magnitude. Yaw rate sensor 355
Detects the yaw rate γ of the vehicle and outputs a signal defining the yaw rate γ. The longitudinal acceleration sensor 356 detects the deceleration _GFR in the longitudinal direction of the vehicle body and outputs a signal defining the height. The lateral acceleration sensor 357 detects the deceleration _GLR in the lateral direction of the vehicle body and outputs a signal defining the height. Wheel load sensor 358 detects the front wheel load W _F of front axle receives from the vehicle body in the vertical direction, and outputs a signal for defining the size. Rear wheel load sensor 359
Is the rear wheel load W _R that the rear wheel axle receives vertically from the vehicle body
And outputs a signal defining its magnitude. Each wheel speed sensor 360 detects the wheel speed of each wheel and outputs a signal defining the magnitude. Each motor rotation position sensor 362 detects the rotation position of each of the motors 20 and 30 of each wheel, and outputs a signal defining the rotation position. Each motor current sensor 364 detects a current actually supplied to the coils of the motors 20 and 30 of each wheel, and outputs a signal defining the actual supplied current value.

On the other hand, first and second drivers 366, 368 are connected to the output side of the ECU 50. First
The driver 366 is provided between the first battery 370 as a power supply and the motor 20 of the electric disk brake 22 for the left and right front wheels. On the other hand, the second driver 368
It is provided between the second battery 372 as a power source and the motor 30 of the electric drum brake 32 of the left and right rear wheels. When the brake pedal 34 is operated, a command is supplied from the ECU 50 to each of the drivers 366 and 368, and in response to the command, each of the drivers 366 and 368 supplies a current from each of the batteries 370 and 372 to each of the motors 20 and 30.

In this embodiment, a main battery 374 is also provided as a power source. This main battery 374
Are independent of the first and second batteries 370, 372. The main battery 374 operates the electric components of the vehicle other than the motors 20 and 30. Therefore, the ECU 50 does not rely on the first and second batteries 370, 372, but on the main battery 3
74 will be activated.

Further, on the output side of the ECU 50, 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). When driving the vehicle, the ECU 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 ECU 50 also performs traction control.

Further, on the output side of the ECU 50, a brake warning lamp 376 as a brake warning device is provided. The brake warning lamp 376 is turned on when an electric failure occurs in the electric disc brake 22 or the electric drum brake 32 to warn the driver of the occurrence of the failure.

In the ROM 342 of the computer 346,
Various routines including a brake control routine and a friction material μ detection routine are stored.

The brake control routine executes various types of brake control. Various types of brake control include basic control,
There are antilock control, traction control, and vehicle stability control (hereinafter, referred to as “VSC”). "Basic control"
Are the operation force sensor 348 and the brake pedal switch 35
0, front wheel load sensor 358, rear wheel load sensor 359, motor rotational position sensor 362 and motor current sensor 36
Based on the output signal from the control unit 4, the distribution of the braking force before and after the vehicle is taken into consideration, and while monitoring the actual values of the motor rotational position and the motor current, the vehicle deceleration corresponding to the operating force f is realized. That is, the motors 20 and 30 are controlled. The “anti-lock control” is based on output signals from the brake pedal switch 350, the wheel speed sensor 360, the motor rotation position sensor 362, and the motor current sensor 364, so that each motor does not have an excessive tendency to lock each wheel during vehicle braking. The control of the braking torque of each wheel is performed by means of 20, 30. "Traction control"
Based on output signals from an accelerator pedal switch 352, an accelerator pedal operation amount sensor 353, a wheel speed sensor 360, a motor rotation position sensor 362, and a motor current sensor 364, each motor is controlled so that the spin tendency of the drive wheels does not become excessive when the vehicle is driven. The control of the drive torque of each drive wheel is performed by means of 20, 30. “VSC” is based on output signals from the steering angle sensor 354, the yaw rate sensor 355, the lateral acceleration sensor 358, the wheel speed sensor 360, the motor rotation position sensor 362, and the motor current sensor 364, and the drift tendency and the spin tendency of the vehicle are determined. The purpose is to control the yaw moment of the vehicle by the braking force difference between the left and right wheels so as not to be excessive.

FIG. 8 is a flowchart showing the brake control routine. This routine is repeatedly executed while the ignition switch of the vehicle is being turned ON. When executing this routine each time, first, in step S1
(Hereinafter simply referred to as “S1”; the same applies to other steps).
Is ON, that is, whether the brake operation is being performed. If it is ON, the determination becomes YES, and the basic control is performed in S2.

FIG. 9 is a flowchart showing the details of step S2 as a basic control routine. First, in S21, is detected operating force f by the operating force sensor 348, then, in S22, the longitudinal acceleration G _FR by various sensors, lateral acceleration G _LR, the front wheel load W _F, the rear wheel load W _R and yaw rate γ Based on this, the target braking force F ^* of each wheel is determined. The ideal braking force front-rear distribution according to the vehicle weight and the vehicle deceleration is realized, and the target braking force F ^{* of} each wheel is set so that the vehicle body does not yaw or skid due to an unexpected braking force difference between the left and right wheels ^. Is determined.

Thereafter, in S24, the friction material μ of the front wheel disc brake 22 (the friction coefficient of the inner pad 106b) is read from the RAM 344. The temporary value of the friction material μ is stored in the RAM 344 in response to turning on of the power of the computer 346, and thereafter, the value of the friction material μ is updated in the RAM 344 by executing a friction material μ detection routine described later.

Subsequently, in S25, the target mode of each wheel is set.
Current value I^*Is determined. For rear wheel drum brake 32
About the target braking force F^*And the target current value I of the motor 30
^*And a predetermined relationship (stored in ROM 342).
Has been determined). In contrast, the front wheel
For the disc brake 22, the target motor current value I ^*
Is applied to the pressing force N of the pair of friction pads 106a and 106b.
On the basis of the fact that^*= F^*/ (Μ · K) is determined using the following equation. In this equation, “K” is constant
Is a number.

Thereafter, in S26, current is supplied to each of the motors 20, 30 at the determined target motor current value I ^* , so that each of the motors 20, 30 is driven.
This completes one execution of this routine.

After S2 in FIG. 8 is executed as described above, in S3, it is determined whether or not antilock control is necessary, that is, whether or not an excessive locking tendency has occurred in the wheels. Is determined. This time, if it is assumed that this is not necessary, the determination is NO, and one execution of this routine ends immediately. However, if it is necessary, the determination is YES, and in S4, the antilock control is executed. You. Subsequently, in S5, it is determined whether or not the continuous execution of the antilock control becomes unnecessary. Unless it becomes unnecessary, the determination is NO and the process returns to S4. If it is not necessary, the determination becomes YES, and one cycle of this routine ends.

On the other hand, the brake pedal switch 3
If 50 is OFF, the determination in S1 is NO, and in S6, it is determined whether traction control is necessary, that is, whether an excessive spin tendency has occurred in the drive wheels. This time, if it is assumed that this is necessary, the determination is YES, and in S7, traction control is executed. Subsequently, in S8, it is determined whether or not continuous execution of the traction control is unnecessary. Unless it becomes unnecessary, the determination is NO and the process returns to S7. If it is not necessary, the determination becomes YES, and one cycle of this routine ends.

When the brake pedal switch 350 is
If it is FF and traction control is not required, the determination in S1 is NO, the determination in S6 is NO, and S
At 9, it is determined whether VSC is required, ie, whether the vehicle has an excessive tendency to drift out or spin. This time, if it is assumed that it is necessary, the determination is YES, and VSC is executed in S10. Subsequently, in S11, it is determined whether or not continuous execution of the VSC is unnecessary. Unless it becomes unnecessary, the determination is NO and the process returns to S10. If it is not necessary, the determination becomes YES, and one cycle of this routine ends.

The friction material μ detection routine is shown in the flowchart of FIG. This routine is also executed alternately and repeatedly for the left front wheel and the right front wheel while the ignition switch of the vehicle is being turned ON. At the time of execution of this routine each time, first, in S31, the right and left front wheels which are the subject of this execution of this routine (hereinafter, referred to as
Anti-lock control ("AB" in the figure) for the "execution target wheel") by the brake control routine.
S ”), traction control (“ TR ”in the figure)
C) and VSC are not being executed. In this case, if it is assumed that any control is being executed, the determination is NO, and one execution of this routine is immediately ended. However, if it is assumed that neither control is being executed, the determination is YES, The process moves to S32.

In S32, it is determined whether or not the signal of the force switch 150 corresponding to the wheel to be executed has changed. It is determined whether it is one of the time when it changes from OFF to ON and the time when it changes from ON to OFF. In this case, if it is assumed that the signal has not changed, the determination is NO, and one execution of this routine is immediately terminated. However, if it is assumed that the signal has changed, the determination is YES, and S
Move to 33.

In S33, the actual motor current value T _A is detected based on the signal from the motor current sensor 364 corresponding to the wheel to be executed. Then, in S34,
Based on the actual motor current value I _A detected, the braking force is set in advance as it should act on the inner pad 106b when the signal of the force switch 150 is changed F ₀ (frictional force) and, executed The friction material μ corresponding to the wheel is detected. Specifically, detected using _{μ = F 0 / (K ·} I A) becomes equation.

Subsequently, in S35, the detected friction material μ is stored in the RAM 344. This completes one execution of this routine.

As is apparent from the above description, in the present embodiment, the motor current sensor 364 constitutes a "brake-related amount sensor", and the ECU 50 of FIG.
Steps S31 to S34 constitute a "friction material friction coefficient estimating device".

Next, a brake system according to a second embodiment of the present invention will be described. However, the same elements as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. Only different elements will be described in detail.

In the first embodiment, the manual brake control device 300 and the mechanical brake 36 as an emergency brake are provided on the left and right rear wheels RL, RR. In the present embodiment, the left and right front wheels FL, FR are provided. Is provided. As shown in FIG.
Are connected to brake pads 106a and 106b of the electric disc brakes 22 of the left and right front wheels FL and FR via a manual brake control device 400, an emergency brake cable 402, and a mechanical brake 406. Therefore, there is a possibility that the mechanical brake 406 is operating when the friction material μ is detected for the front wheel disc brake 22. On the other hand, when the friction material μ is detected, the mechanical brake 40
If 6 is operating, its detection accuracy may be reduced. Therefore, in the present embodiment, when the mechanical brake 406 is operated, the detection of the friction material μ is prohibited. In this embodiment, when the mechanical brake 406 is in the activated state, the second piston of the manual brake control device 400 (corresponding to the second piston 318 of the manual brake control device 300) is activated. ON, otherwise O
FF is detected by a second piston operation switch 410.

In this embodiment, the routine shown in the flowchart of FIG. 12 is stored in the ROM 342 as the friction material μ detection routine.

First, in S101, it is determined whether or not the second piston operation switch 410 is OFF.
If it is ON, the determination becomes NO, and one execution of this routine is immediately terminated. If it is OFF, the determination becomes YES. Then, S102 to S106 are replaced with S31 to S106 in FIG.
This is executed in the same manner as in S35. This completes one execution of this routine.

Next, a brake system according to a third embodiment of the present invention will be described. However, the same elements as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. Only different elements will be described in detail.

In this embodiment, a fade determination routine is provided in addition to the brake control routine and the friction material μ detection routine in the first embodiment. The fade determination routine is shown in the flowchart of FIG.

This routine is executed for the left front wheel and the right front wheel.
Executed alternately and repeatedly. During each run,
First, in S301, the signal of the force switch 150 changes.
It is determined whether it has been done. Assume this has not changed
If this is the case, the determination is NO, and the routine
The line ends. In contrast, this time the force switch 150
Assuming that the signal has changed, the determination is YES, and S
At 302, the actual motor is
Current value I_AIs detected. Then in S303
And the detected actual motor current value I_AFirst implementation based on
In the same manner as the friction material μ detection routine in the
The material μ is detected. Subsequently, in S304, the detected
Friction material μ is the reference value μ₀It is determined whether or not
You. Reference value μ ₀If it is below, the determination is YES, and S3
At 05, the front wheel disc brake 22 fades
Is determined to have occurred and the brake warning
When the lamp 376 is turned on,
The driver is warned that something is wrong. On the contrary,
The detected friction material μ is the reference value μ₀S30 if larger
4 is NO, and in S306, the front wheel disc
It is determined that no fade has occurred on the brake 22
As well as turning off the brake warning lamp 376
Signal is output. In any case, this routine
Is completed.

Next, a brake system according to a fourth embodiment of the present invention will be described. However, the same elements as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. Only different elements will be described in detail.

In this embodiment, a brake abnormality check routine is provided in addition to the brake control routine and the friction material μ detection routine in the first embodiment. The brake abnormality check routine is shown in the flowchart of FIG.

This routine is also executed alternately and repeatedly for the front left wheel and the front right wheel. In each execution, first, in S401, the operation force sensor 348 detects the operation force f. Next, in S402, the detected operating force f is whether greater than the reference value f ₀ is determined. If it is larger than the reference value f ₀ , the determination is YES, and in S403, it is determined whether the force switch 150 is ON. The reference value f ₀ is set in advance so that the force switch 150 is always turned on when the front wheel disc brake 22 is normal. Therefore, if the determination is NO because the force switch 150 is OFF, S4
At 06, it is determined that there is an abnormality in the front wheel disc brake 22, and the brake warning lamp 376 is turned on. This completes one execution of this routine.

On the other hand, when the force switch 150 is turned on,
If there is, the determination in S403 is YES and S40
4, the detected operating force f is equal to the reference value f.₁Smaller
It is determined whether or not it is. Reference value f₁If less
Is YES in step S405, and the power switch is
It is determined whether switch 150 is OFF. Reference value f
₁If the front disc brake 22 is normal,
It is set in advance so that the switch 150 is turned off.
You. Therefore, because the force switch 150 is ON
If the determination is NO, in S406 the front wheel disc
It is determined that there is an abnormality in the brake 22, and the brake
The notification lamp 376 is turned on. This completes the routine
One run ends.

On the other hand, if the detected operation force f is equal to or smaller than the reference value f ₀ , the determination in S402 is NO, and the flow shifts to S404. At this time, when the detected operation force f is the reference value f ₁ or more, the determination of S404 becomes NO, immediately, one cycle of execution of the routine is terminated.

In addition, since the reference value f ₀ is generally set to a value larger than the reference value f ₁ , if the determination in S402 is YES, the determination in S404 does not become YES.

Next, a brake system according to a fifth embodiment of the present invention will be described. However, the same elements as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. Only different elements will be described in detail.

In this embodiment, a pressing force sensor 430 is added to the pressing member 134 as shown in FIG. The pressing force sensor 430 detects a force by which the pressing member 134 presses the inner pad 106b as a continuous value.

In the present embodiment, the ROM 342 stores
A front wheel brake control routine represented by a flowchart in FIG. 16 is stored.

This routine is executed alternately and repeatedly for the left and right front wheels FL and FR. At the time of each execution, first, in S451, the brake pedal switch 350
Is determined to be ON. If it is OFF, the determination is NO, and one cycle of this routine is immediately terminated. On the other hand, if ON, the determination is YES,
The process moves to S452. In S452, the operation force f is detected by the operation force sensor 348. Then, S45
At 3, the target braking force F ^{* for the} front wheels is determined based on the detected operating force f. Note that S452 and S453 can have the same contents as in the first embodiment. Subsequently, in S454, the actual signal S _A thereof is input from the pressing force sensor 430. afterwards,
In S455, the conversion function g (S) is read from the RAM 344.
Is read. The conversion function g (S) is a function for converting the actual signal S _A into the actual braking force F _{A. A} temporary function is stored in the RAM 344 in response to power-on of the computer 346, and thereafter, a conversion function described later is performed. By executing the function correction routine, the conversion function g (S) is corrected as needed.

Thereafter, in S456, the actual braking force F _A is calculated by substituting the input actual signal S _A into the read conversion function g (S). Then, S4
In 57, on the basis of the difference between the computed actual braking force F _A and the determined target braking force F ^*, the control amount ΔI of the current value I of the motor 20 is determined. Than is appropriate motor current control amount ΔI to the actual braking force F _A to coincide with the target braking force F ^* is determined. Thereafter, in S458, the motor 20 is driven based on the determined motor current control amount ΔI. This completes one execution of this routine.

FIG. 17 is a flowchart showing the conversion function correction routine. This routine also has front left and right wheels F
The processing is performed alternately and repeatedly for L and FR. At the time of each execution, first in S501, the force switch 15
It is determined whether the signal of 0 has changed. If it is assumed that no change has occurred this time, the determination is NO, and one cycle of this routine ends immediately. In contrast, this determination is YES Assuming to have changed, at S502, from the pressing force sensor 430 is a real signal S _A of its input. Thereafter, in S503, the true signal S _T from the input real signal S _A , that is, the signal to be output by the pressing force sensor 430 when the signal of the force switch 150 changes, is subtracted to obtain the signal deviation amount ΔS Is calculated. As shown in the graph of FIG. 18, the signal deviation amount ΔS is a graph representing the actual characteristics of the pressing force sensor 430.
This corresponds to the amount of deviation from the graph representing the true characteristics.

Subsequently, in S504, the calculated signal
The absolute value of the signal deviation amount ΔS is equal to the reference value ΔS. ₀Greater than or not
Is determined. If it is larger, the determination is YES,
In S505, the conversion function g (S) is corrected. Figure
As shown in FIG. 19, a graph representing the conversion function g (S) before correction
The rough is parallel to the coordinate axis representing the signal S, and
In the same direction as the direction in which the characteristics deviate from the true characteristics.
The displacement function g (S) is moved by the same amount as the displacement amount.
Is corrected. Thereafter, in S506, the supplement
The corrected conversion function g (S) is stored in the RAM 344.
You. On the other hand, the absolute value of the calculated signal deviation amount ΔS
Is the reference value ΔS₀If it is less than or equal to
No, S505 and S506 are skipped
You. In any case, the execution of this routine once
Ends.

As is clear from the above description, in the present embodiment, the conversion function g (S) corresponds to the “relation”,
In addition, the part of the ECU 50 that executes S454 to S456 in FIG. 16 and S501 to S505 in FIG. 17 constitutes a “wheel braking force estimation device”.
The part that executes 505 constitutes "relation correction means".

Next, a brake system according to a sixth embodiment of the present invention will be described. However, the same reference numerals are used for the elements common to the fifth embodiment, and the detailed description is omitted. Only different elements will be described in detail.

In this embodiment, as shown in FIG. 20, the pressing force sensor 430 is omitted, and a braking force sensor 450 is provided instead. The braking force sensor 450 detects a force received from the inner pad 106b during braking as a braking force and detects the braking force as a continuous value. The braking force sensor 450 is provided on the receiving portion 110b in series with the force switch 150. The braking force sensor 450 includes a strain gauge, a piezoelectric element,
It is mainly composed of pressurized conductive rubber and the like.

In this embodiment, the ROM 342 stores
A front wheel brake control routine represented by a flowchart in FIG. 21 is stored.

This routine is executed alternately and repeatedly for the front left and right wheels FL, FR. At the time of each execution, first, in S551, the brake pedal switch 350
Is determined to be ON. If it is OFF, the determination is NO, and one cycle of this routine is immediately terminated. On the other hand, if ON, the determination is YES,
The process moves to S552. In S552, the operation force f is detected by the operation force sensor 348. After that, S55
At 3, the target braking force F ^{* for the} front wheels is determined based on the detected operating force f. Note that S552 and S553 can have the same contents as in the first embodiment. Subsequently, in S554, the actual signal S _A thereof is input from the braking force sensor 450. afterwards,
In S555, the conversion function h (S) is read from the RAM 344.
Is read. The conversion function h (S) is a function for converting the actual signal S _A into the actual braking force F _{A. A} temporary function is stored in the RAM 344 when the computer 346 is turned on. By executing the power sensor calibration routine, the conversion function h (S) is corrected as needed.

Thereafter, in S556, the actual braking force F _A is calculated by substituting the input actual signal S _A into the read conversion function h (S). Then, S5
In 57, on the basis of the difference between the computed actual braking force F _A and the determined target braking force F ^*, the control amount ΔI of the current value I of the motor 20 is determined. Than is appropriate motor current control amount ΔI to the actual braking force F _A to coincide with the target braking force F ^* is determined. Thereafter, in S558, the motor 20 is driven based on the determined motor current control amount ΔI. This completes one execution of this routine.

FIG. 22 is a flowchart showing a braking force sensor calibration routine. This routine is also executed alternately and repeatedly for the left and right front wheels FL and FR. At the time of each execution, first in S601, the force switch 1
It is determined whether the signal at 50 has changed. If it is assumed that no change has occurred this time, the determination is NO, and one cycle of this routine ends immediately. In contrast, this determination is YES Assuming to have changed, at S602, the real signal S _A of it from the braking force sensor 450 is input. Thereafter, in S503, the input real signal S _A is converted into the true signal S _T , that is, the force switch 150.
Is subtracted from the signal to be output by the braking force sensor 450 when the signal of. Since the signal deviation amount ΔS is the same as that in the fifth embodiment, detailed description will be omitted.

Subsequently, in S604, the calculated signal
The absolute value of the signal deviation amount ΔS is equal to the reference value ΔS. ₀Greater than or not
Is determined. If it is larger, the determination is YES,
In S605, the conversion function h (S) is corrected. This
Is the same as that in the fifth embodiment.
Therefore, detailed description is omitted. Then, in S606
Then, the corrected conversion function h (S) is stored in the RAM 344.
Is done. On the other hand, the calculated signal deviation amount ΔS
The absolute value is the reference value ΔS₀If it is less than or equal to
If the determination is NO, S605 and S606 are skipped
Is done. In either case,
Execution ends.

As is clear from the above description, in the present embodiment, the conversion function h (S) corresponds to the “relation”,
A part of the ECU 50 that executes S554 to S556 in FIG. 21 and S601 to S605 in FIG. 22 constitutes a “wheel braking force estimation device”.
The part that executes 605 constitutes "relation correction means".

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

[Brief description of the drawings]

FIG. 1 is a system diagram showing the overall configuration of a brake system having electric disc brakes for left and right front wheels according to a first embodiment of the present invention.

FIG. 2 is a plan sectional view showing the electric disk brake.

FIG. 3 is a cross-sectional view of FIG. 2 cut along a surface of an inner pad 106b.

FIG. 4 is a side view showing an electric drum brake for right and left rear wheels in FIG. 1;

FIG. 5 is an enlarged view showing a shoe expansion actuator in FIG. 4;

FIG. 6 is an enlarged side sectional view showing the manual brake control device in FIG. 1;

FIG. 7 is a graph for explaining an operation start timing of a second piston in FIG. 6 in relation to an operation force f and a vehicle body deceleration.

FIG. 8 is a flowchart showing a brake control routine stored in a ROM in FIG. 1;

FIG. 9 is a flowchart showing details of S2 in FIG. 8 as a basic control routine.

FIG. 10 is a flowchart showing a friction material μ detection routine stored in the ROM.

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

12 is a flowchart illustrating a friction material μ detection routine stored in a ROM of a computer of the ECU in FIG. 11;

FIG. 13 is a flowchart illustrating a fade determination routine stored in a ROM of a computer of the brake system according to the third embodiment of the present invention.

FIG. 14 is a flowchart illustrating a brake abnormality check routine stored in a ROM of a computer of the brake system according to the fourth embodiment of the present invention.

FIG. 15 is a plan sectional view showing an electric disc brake for left and right front wheels in a brake system according to a fifth embodiment of the present invention.

FIG. 16 is a computer RO of the brake system.
5 is a flowchart showing a front wheel brake control routine stored in M.

FIG. 17 is a flowchart showing a conversion function correction routine stored in the ROM.

FIG. 18 is a graph for explaining the contents of the conversion function correction routine.

FIG. 19 is another graph for explaining the contents of the conversion function correction routine.

FIG. 20 is a plan sectional view showing an electric disc brake for left and right front wheels in a brake system according to a sixth embodiment of the present invention.

FIG. 21 is a computer RO of the brake system.
5 is a flowchart showing a front wheel brake control routine stored in M.

FIG. 22 is a flowchart showing a braking force sensor calibration routine stored in the ROM.

[Explanation of symbols]

 Reference Signs List 20 ultrasonic motor 22 electric disc brake 50 ECU 104 disc 106 brake pad 132 ball screw mechanism 134 pressing member 150 force switch 430 pressing force sensor 450 braking force sensor

Claims (5)

[Claims] A rotating member which rotates together with the wheel, a friction member which is brought into contact with the rotating member and suppresses rotation of the wheel, and wherein the friction member is prevented from rotating along with the rotating member in the contact state. A receiving member that receives the friction material, a pressing device that presses the friction material and makes contact with the rotating body, and that is provided between the friction material and the receiving member, receives a force from the friction material and receives the received force. A force switch that outputs a signal that changes between two states depending on whether the value is equal to or greater than a non-zero set value. 2. The rotating body is a disk having a friction surface on a surface thereof, the friction material is a brake pad brought into contact with a friction surface of the disk, and the force switch is provided between the brake pad and the receiving pad. 2. The brake according to claim 1, wherein the brake pad is provided at a position between the member and a position where the gap decreases as the amount of the rotation of the brake pad increases. 3. 3. A brake according to claim 1, wherein said pressing device outputs a signal which continuously changes in accordance with an amount related to a pressing force for pressing said friction material. A frictional material friction that estimates a friction coefficient of the frictional material based on a relationship between a signal output from the pressing force-related amount sensor when the signal of the force switch changes and the set value. A brake system comprising a coefficient estimating device. 4. The brake according to claim 1, further comprising a braking force applied to the wheel by the brake or a brake-related amount related to a pressing force of the pressing device pressing the friction material. A brake-related quantity sensor that outputs a signal that continuously changes in response to the output signal of the brake-related quantity sensor; and a wheel based on a predetermined relationship between the output signal and the wheel braking force. A wheel braking force estimating device for estimating a braking force, wherein the device corrects the relationship based on a signal output by the brake-related amount sensor when a signal of the force switch changes. Brake system. 5. The wheel braking force estimating device corrects the relationship based on a difference between an actual signal output by the brake-related quantity sensor and a true signal to be output when a signal of the force switch changes. The brake system according to claim 4, further comprising a relationship correction unit that performs the following.