JP2014121964A - Electric brake device and brake system with the device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric brake device and a brake system, which are capable of detecting a wheel speed without equipping with a separate wheel speed sensor.SOLUTION: An electric brake device 1 includes a disk, and first and second pads enabled to apply pressure to respectively corresponding side-surfaces of the disk. The first pad is provided with a strain sensor 40 for detecting a strain of the first pad in a thrust direction. An ECU 53 for use in controlling the electric brake device 1 includes: a strain variation pattern storage part 55 for storing a strain variation pattern P corresponding to one cycle of a wheel; and an anti-lock action determination part 56 for determining applicability of executing an anti-lock action on the basis of the strain variation pattern stored in the strain variation pattern storage part 55 and the strain generated in the first pad 6.

Description

  The present invention relates to an electric brake device and a brake system including the same.

  An anti-lock system (ABS) is generally employed in the hydraulic brake device (see Patent Document 1). In recent years, electric brake devices have been developed as brake devices in place of conventional hydraulic brake devices. This electric brake device converts a rotational driving force of an electric motor into a linear force, and applies a braking force to the disk by pressing a pad against the rotating disk (see Patent Document 2).

JP 2011-116237 A JP 2000-110860 A

In such an electric brake device, a load sensor is disposed on the pad. The braking force is controlled by adjusting the pressing force against the disc based on the magnitude of the load acting on the pad.
By the way, in a brake system including both an electric brake device and a hydraulic brake device, it is possible to suppress the locking of the wheels by causing the ABS of the hydraulic brake device to perform an antilock operation. In general, whether or not the anti-lock operation can be performed is determined based on both the wheel speed and the vehicle speed. If a wheel speed sensor for obtaining the wheel speed is separately provided, the cost may be increased by the amount of the wheel sensor, and the weight may be increased by the amount of the wheel sensor.

  The present invention has been made under such a background, and it is an object of the present invention to provide an electric brake device capable of detecting a wheel speed without separately providing a wheel speed sensor, and a brake system including the same.

  In order to achieve the above-mentioned object, the invention according to claim 1 generates a braking force by pressing the pads (6, 7) by driving the electric actuator (13) against the disk (2) rotating integrally with the wheel. The electric brake device (1) to be operated is a load detection means (40) for detecting the magnitude of a load generated on the pad, and a load that is a fluctuation pattern of the magnitude of the load when the wheel is rotated. Wheel speed for calculating the wheel speed of the wheel based on the load fluctuation pattern storage means (55) for storing the fluctuation pattern (P), the load fluctuation detected by the load detection means, and the load fluctuation pattern. An electric brake device including a calculation means (56).

In this section, the alphanumeric characters in parentheses represent reference signs of corresponding components in the embodiments described later, but the scope of the claims is not limited to the embodiments by these reference numerals.
According to this configuration, when the wheel rotates, the magnitude of the load input from the wheel differs according to the rotation angle position of the wheel, and therefore, the load generated on the pad during braking is the circumferential position when the wheel rotates. Fluctuates depending on The variation of the load generated on the pad varies depending on the rotational angle position of the wheel. Therefore, one load fluctuation pattern is obtained every time the wheel makes one revolution, and such a load fluctuation pattern repeatedly appears a plurality of times as the wheel rotates. Therefore, by storing the load fluctuation pattern in the load fluctuation pattern storage means and comparing the load fluctuation based on the detection output of the load detection means with the load fluctuation pattern stored in the load fluctuation pattern storage means, the wheel The speed can be calculated. Therefore, the wheel speed can be detected without separately providing a wheel speed sensor.

The invention according to claim 2 is the electric brake device according to claim 1, wherein the load detecting means includes a strain detecting means (40) for detecting the magnitude of strain of the pad.
According to this configuration, the magnitude of the load acting on the pad can be detected by detecting the magnitude of the distortion of the pad.
The invention according to claim 3 is the electric brake device according to claim 1, the ABS operation means (52) for executing the anti-lock operation for suppressing the lock of the wheel, and the ABS. The brake system (50) includes an antilock operation determination unit (56) that determines whether or not the antilock operation can be performed by the operation unit based on information including the wheel speed calculated by the wheel speed calculation unit. .

  According to this configuration, whether or not the anti-lock operation can be performed by the ABS operation unit is determined based on information including the wheel speed obtained as a result of the calculation by the wheel speed calculation unit. Therefore, it is possible to determine whether or not the antilock operation can be performed without separately providing a wheel speed sensor. Thereby, weight reduction of a brake system can be achieved.

It is a schematic sectional drawing of the electric brake device of one Embodiment of this invention, and has shown the time of non-braking. It is a schematic sectional drawing of an electric brake device, and has shown at the time of braking. It is a figure for demonstrating the electric constitution of the brake system containing an electric brake device. It is a flowchart which shows the process of anti-lock operation | movement determination by ECU. It is a figure which shows the fluctuation | variation of the magnitude | size of the distortion of a 1st pad.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic cross-sectional view of an electric brake device 1 according to an embodiment of the present invention in a non-braking state. FIG. 2 is a schematic sectional view of the electric brake device 1 in a braking state. 1 and 2, an electric brake device 1 is a device that applies a braking force by friction to a disk 2 that rotates integrally with a wheel of an automobile or the like.

  The electric brake device 1 includes, for example, a floating type caliper 3 supported so as to be movable by a knuckle (not shown) and the like, and a first backup supported by the caliper 3 so as to be able to approach / separate from each other. The first pad 6 and the second backup plate 5 are fixed to the first backup plate 4 and the second backup plate 5, respectively, and the corresponding side surfaces of the disk 2 can be pressed as shown in FIG. And a pad 7. The first pad 6 is provided with a strain sensor (strain detection means) 40 for detecting strain in the thrust direction ST, which will be described later, of the first pad 6.

The caliper 3 includes a first body 8 and a second body 9 that are fixed to each other, and a cover 10 that is fixed to the second body 9. The first body 8 includes a main body portion 8A and an arm portion 8C connected to the main body portion 8A via a bridging portion 8B.
The first back plate 4 is fixed to one end 12A of a support shaft 12 supported in an axial direction (corresponding to a thrust direction ST described later) in a support hole 11 inserted through the main body portion 8A. The other end 12 </ b> B of the support shaft 12 is fixed to the piston 25. The second backup plate 5 is fixed to the arm portion 8C. The second body 9 is fixed to the main body portion 8A.

The caliper 3 functions to generate a braking force by pressing the pads 6 and 7 against the disk 2. Specifically, the caliper 3 includes an electric actuator 13 that generates a thrust force in a thrust direction ST parallel to the wheel axis direction X1, and a transmission mechanism 14 that transmits the thrust force generated by the electric actuator 13 to the pads 6 and 7. Is provided.
The electric actuator 13 includes an electric motor 16 having a motor housing 16A fixed to a mounting stay 15 extended from the second body 9 and a rotating shaft 16B as an output shaft, while reducing the rotational output of the electric motor 16. A gear mechanism 17 for transmission and a ball screw mechanism 18 as a motion conversion mechanism for converting the rotational motion transmitted through the gear mechanism 17 into a linear motion in the thrust direction ST are provided. The ball screw mechanism 18 is taken as an example of the motion conversion mechanism included in the electric actuator 13A, but a planetary gear mechanism may be adopted instead.

  The gear mechanism 17 includes a drive gear 19 attached to one end of the rotary shaft 16B so as to be integrally rotatable, an idle gear 20 that meshes with the drive gear 19, and a driven gear 21 that meshes with the idle gear 20 and rotates around the central axis C1. It has. The idle gear 20 is rotatably supported by the second body 9. The driven gear 21 is connected to the ball nut 24 via a connecting portion 33 that passes through an insertion hole 32 formed in the second body 9 so as to rotate in synchronization with the rotation of the ball nut 24 described below. Yes. The cover 10 is fixed to the second body 9 so as to cover the gear mechanism 17.

The ball screw mechanism 18 includes a screw shaft 22 as an output member whose rotation is restricted, and a ball nut 24 as an input member screwed into the screw shaft 22 via a ball 23 and restricted in axial movement. ing. A piston 25 is fixed to one end 22 </ b> A of the screw shaft 22.
Specifically, the ball nut 24 is supported by a rolling bearing 30 and a rolling bearing 31 that are fixed to the inner periphery of the second body 9. The outer periphery of the ball nut 24 is fixed to the inner rings of the rolling bearing 30 and the rolling bearing 31, respectively, and thereby the axial movement of the ball nut 24 is restricted.

  The other end 22 </ b> B of the screw shaft 22 is inserted through a support hole 27 provided in the second body 9. A guide groove 28 extending in the axial direction is formed in the support hole 27. On the outer periphery of the other end portion 22B of the screw shaft 22, a convex portion 29 that protrudes radially outward and engages with the guide groove 28 is provided. The rotation of the ball nut 24 is restricted by the engagement between the convex portion 29 and the guide groove 28. Further, the guide groove 28 functions to guide the movement of the ball nut 24 in the axial direction (corresponding to the thrust direction ST) via the convex portion 29.

The rotation of the rotating shaft 16B of the electric motor 16 is transmitted through the gear mechanism 17, and the ball nut 24 is rotated. As the ball nut 24 rotates, the screw shaft 22 moves in the axial direction (thrust direction ST).
During braking of the electric brake device 1, the thrust force generated by the electric actuator 13 is transmitted to the first pad 6 side via the transmission mechanism 14, and the first pad 6 is pressed to the disk 2 side as shown in FIG. Then, the first pad 6 is in a direction opposite to the rotation direction of the disk 2 with respect to the disk 2 (for example, a direction perpendicular to the paper surface toward the front side of the paper surface) (for example, a direction orthogonal to the paper surface toward the back side of the paper surface). The braking force due to the frictional force is exerted.

  FIG. 3 is a diagram for explaining an electrical configuration of the brake system 50 including the electric brake device 1. The brake system 50 includes an electric brake device 1 and a hydraulic brake device 51 mounted on the same vehicle as the electric brake device 1. The brake system 50 includes an electric brake device 1 and a hydraulic brake device 51 that is mounted on the same vehicle as the electric brake device 1 and drives a hydraulic brake caliper (not shown). In the brake system 50, the electric brake device 1 functions as auxiliary braking means that plays an auxiliary role. The hydraulic brake device 51 has an ABS (Antilock Brake System) function (ABS operation means) 52. The electric brake device 1 and the ABS function 52 are provided for each wheel in a one-to-one correspondence. When any of the wheels is locked, the hydraulic brake device 51 intermittently decreases the brake fluid pressure of the wheel. The ABS function 52 is a known configuration and is equivalent to the ABS function described in Japanese Patent Application Laid-Open No. 2011-116237.

  The brake system 50 includes an ECU (Electronic Control Unit) 53 for controlling the electric brake device 1 and the hydraulic brake device 51. The ECU 53 includes a brake control unit 54 for controlling the braking operation of the electric brake device 1, a strain variation pattern storage unit (load variation pattern storage unit) 55 for storing a strain variation pattern (load variation pattern) P, An antilock operation determination unit (antilock operation determination unit) 56 that determines whether or not the antilock operation can be performed by the ABS function 52 and an antilock operation control unit 57 that controls execution of the antilock operation are included. These function processing units are realized by software, for example, by executing predetermined program processing.

The strain variation pattern storage unit 55 stores a strain variation pattern P (described later) corresponding to one cycle of the wheel. This distortion variation pattern P is a pattern obtained by an experiment using the wheel.
The brake controller 54 is provided with a detection output of the strain sensor 40 of the electric brake device 1. The brake control unit 54 can detect the magnitude of the load acting on the first pad 6 based on the detection output of the strain sensor 40, and execute / stop the rotation driving of the electric motor 16 based on the detection output. The amount of rotation is controlled.

  The anti-lock operation determination unit 56 is mounted on the vehicle and the vehicle speed of the vehicle, including the strain variation pattern stored in the strain variation pattern storage unit 55, the detection output (distortion of the first pad 6) provided from the strain sensor 40, and the like. It is determined whether or not the anti-lock operation can be executed based on the detection output from the vehicle speed sensor 58 for detecting (anti-lock operation determination). The “brake system” described in the claims includes the electric brake device 1, an ABS function 52, and an antilock operation determination unit 56. The antilock operation determination by the antilock operation determination unit 56 will be specifically described below.

FIG. 4 is a flowchart showing an anti-lock operation determination process by the anti-lock operation determination unit 56 (ECU 53). FIG. 5 is a diagram illustrating a variation in the magnitude of distortion of the first pad 6 during the rotation of the wheel.
As shown in FIG. 4, the antilock operation determination unit 56 refers to the detection output of the strain sensor 40 during braking of the electric brake device 1 (step S1). At this time, the magnitude of the strain of the first pad 6 detected by the strain sensor 40 varies according to the rotational angle position of the wheel, as shown in FIG. More specifically, the variation in the strain magnitude of the first pad 6 forms one pattern (strain variation pattern) corresponding to one cycle of the wheel. Such fluctuation is applied to the first pad 6 during braking of the electric brake device 1 because the magnitude of the load input from the wheel differs according to the rotational angle position of the wheel when the wheel rotates. It is considered that the magnitude of the load is caused by fluctuations according to the rotation angle position at the time of rotation of the wheel. Therefore, a distortion variation pattern corresponding to one cycle of the wheel appears repeatedly a plurality of times as the wheel rotates. In this embodiment, the strain variation pattern storage unit 55 stores a strain variation pattern P corresponding to one cycle of the wheel obtained by an experiment using the wheel.

Next, the anti-lock operation determination unit 56 compares the strain variation based on the detection output of the strain sensor 40 with the strain variation pattern P stored in the strain variation pattern storage unit 55, and calculates the wheel speed from the comparison result. (Step S2).
Next, the antilock operation determination unit 56 determines whether or not the antilock operation can be executed based on the calculated wheel speed and the vehicle speed obtained from the vehicle speed sensor 58 (step S3). Specifically, when it can be determined from the wheel speed and the vehicle speed that the wheel is in the locked state, it is determined to perform the anti-lock operation, but from the wheel speed and the vehicle speed, it is determined that the wheel is in the locked state. If not, it is determined that the antilock operation is not executed. When the antilock operation determination unit 56 determines that the antilock operation is performed, the antilock operation control unit 57 controls the ABS function 42 of the hydraulic brake device 51 to execute the antilock operation.

  As described above, according to this embodiment, the strain variation pattern P is stored in the strain variation pattern storage unit 55, and the strain variation based on the detection output of the strain sensor 40 is stored in the strain variation pattern storage unit 55. The wheel speed can be calculated by comparing with the strain variation pattern P. Therefore, by referring to the detection output from the vehicle speed sensor 58, it is possible to determine whether or not the antilock operation can be performed. Therefore, it is possible to determine whether or not the antilock operation can be performed without separately providing a wheel speed sensor that directly detects the magnitude of the wheel speed. Thereby, weight reduction of the brake system 50 can be achieved.

As mentioned above, although one Embodiment of this invention was described, this invention can also be implemented with another form.
For example, in the above-described embodiment, the calculation of the wheel speed shown in step S2 and the determination of whether or not to execute the antilock operation shown in step S3 are described as separate steps. However, each step of steps S2 and S3 Can also be performed in a batch.

  In the above-described embodiment, the case where the strain variation pattern storage unit 55 stores the strain variation pattern P having a length corresponding to one cycle of the wheel has been described as an example. However, the strain variation pattern storage unit 55 stores the strain variation pattern P. The strain variation pattern P may have a length exceeding one cycle of the wheel, and the strain variation pattern P corresponding to only a part of one cycle of the wheel is stored in the strain variation pattern storage unit 55. Also good.

Moreover, although the case where the strain variation pattern P is stored in the strain variation pattern storage unit 55 as an example of the load variation pattern has been described as an example, it can be stored in the form of a load variation pattern.
In addition, the strain sensor 40 that detects the strain of the first pad 6 has been described as an example of the strain detection unit. Can also be adopted. Further, although the strain detecting means is employed as the load detecting means, the magnitude of the load acting on the pads 6 and 7 can also be directly detected. As an example of this, a case where a sensor for detecting the magnitude of a load acting on the support shaft 12 via the first pad 6 is employed as a load detection sensor can be cited.

Moreover, although ECU53 which has the anti-lock action determination part 56 was demonstrated as what controls the electric brake device 1 and the hydraulic brake device 51, ECU53 which has the anti-lock action determination part 56 is the electric brake device 1 and the hydraulic brake device. The structure which controls only any one of 51 may be sufficient.
In addition, various design changes can be made within the scope of matters described in the claims.

DESCRIPTION OF SYMBOLS 1 ... Electric brake device, 2 ... Disc, 6 ... 1st pad, 7 ... 2nd pad, 13 ... Electric actuator, 40 ... Strain sensor (strain detection means), 50 ... Brake system, 52 ... ABS function, 55 ... Strain Fluctuation pattern storage unit (load variation pattern storage means), 56... Antilock operation determination unit, P... Strain variation pattern (load variation pattern)

Claims (3)

An electric brake device that generates a braking force by pressing a pad on a disk that rotates integrally with a wheel by driving an electric actuator,
Load detection means for detecting the magnitude of the load generated in the pad;
Load variation pattern storage means for storing a load variation pattern that is a variation pattern of the magnitude of the load when rotating the wheel;
An electric brake device including wheel speed calculation means for calculating a wheel speed of the wheel based on the load fluctuation detected by the load detection means and the load fluctuation pattern.   The electric brake device according to claim 1, wherein the load detection unit includes a strain detection unit that detects a magnitude of distortion of the pad. The electric brake device according to claim 1 or 2,
ABS operation means for executing an anti-lock operation for suppressing the lock of the wheel;
A brake system comprising: an anti-lock operation determination unit that determines whether or not the anti-lock operation can be performed by the ABS operation unit based on information including a wheel speed calculated by the wheel speed calculation unit.

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