JP2000018293A - Braking device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a bragging motion caused by a friction material brought into contact with a rotor in non-braking time in a braking device for a vehicle, and to enhance the responsiveness of braking. SOLUTION: The electronic control device 5 of an electric drive braking device which presses each pad 7 by means of an electrically driven actuator 10 to bring into slide contact with a disc rotor 6, is equipped with a control function capable of increasing a clearance generating between each pad 7 and a disc rotor 6 much more at the time when an accel pedal 2 is turned on than that at the time when the accel pedal 2 is turned off.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called by-wire type vehicle brake device (hereinafter referred to as an electric drive brake device).

[0002]

2. Description of the Related Art An electric drive brake device controls an electric actuator by an electronic control unit based on an output of a sensor for detecting a brake operation force or a brake operation amount so as to generate a braking force corresponding to the output. Then, the friction material is pressed against the rotor to brake the wheels.

[0003] By the way, in a vehicle brake system, a clearance generated between a friction material and a rotor during non-braking is defined by:
It is secured by the following method.

(I) The brake piston is returned by the elastic restoring force of the piston seal. (Ii) Return the friction material and the brake piston with the force of the spring. (Iii) As shown in Japanese Patent Application Laid-Open No. 9-137841, a thrust sensor for detecting the pressing pressure of the friction material and a sensor for detecting the position of the friction material are provided, and the position at which the output of the thrust sensor becomes zero is set as the origin. Then, the propulsion body of the electric actuator is moved backward until the clearance reaches a specified value based on the output of the position sensor.

[0005] In these methods, a predetermined fixed clearance is secured when the brake is released.

[0006]

If the above clearance is too small, the frictional material contacts the rotor during non-braking due to the runout of the rotor, so-called drag occurs, and the drag reduces the fuel efficiency of the vehicle and reduces the friction material. It may cause shortening of service life and brake judder.

On the other hand, if the clearance is too large, the time from when the brake pedal is depressed until the braking force is generated becomes longer, causing problems such as a delay in braking response.

Accordingly, although sufficient consideration is given to the setting of the clearance, the above-mentioned conventional method cannot change the set clearance value, so that it is necessary to satisfy both the demand for the reduction in drag and the improvement in responsiveness. However, there is no choice but to find a compromise value that satisfies each requirement half-and-half, and cannot obtain satisfactory results.

Accordingly, an object of the present invention is to achieve both reduction of drag and improvement of responsiveness by utilizing the features of an electric drive brake device capable of performing high-accuracy control.

[0010]

According to the present invention, there is provided a brake apparatus for a vehicle in which an electric actuator which receives an operation command from an electronic control unit presses a friction material to slidably contact a rotor. An accelerator pedal ON / OFF detection means is provided so that the control of the electric actuator by the electronic control unit is performed so that the clearance between the rotor and the friction material is larger when the accelerator pedal is ON than when the accelerator pedal is OFF. It was done.

The ON / OFF detecting means for the accelerator pedal may be a switch or a switch-type sensor. If the vehicle has an accelerator switch, it can be used in common.

The clearance control when the accelerator pedal is turned on and when the accelerator pedal is turned off is a method in which the origin of zero clearance is detected by a pressure sensor or the like, and the amount of retraction of the actuator from the origin is controlled using a position sensor or an encoder. Can be done with

[0013]

When the accelerator pedal is ON, the driver has no intention of braking, and even if the clearance between the friction material and the rotor is increased, the braking is not delayed. Therefore, when the accelerator pedal is turned on, the above-described clearance is increased to reduce drag.

On the other hand, when the accelerator pedal is turned off, the electric actuator operates to reduce the clearance, thereby eliminating a delay in braking response.

Although the clearance between the accelerator pedal and the brake is applied after the accelerator pedal is turned off, the clearance is small and dragging is likely to occur. However, since the accelerator pedal is kept off for a long time without applying the brake, it is unlikely. However, even if the clearance is made smaller when the accelerator pedal is turned off and the response is increased, the effect of dragging is not significant.

[0016]

FIG. 1 shows an embodiment of an electric drive brake device according to the present invention. This is an example of application to a floating disc brake, in which 1 is a brake pedal,
2 is an accelerator pedal, 3 is a treading force sensor for detecting the depressing force of the brake pedal 1, 4 is ON of the accelerator pedal 2,
This is an accelerator switch that detects OFF. The pedal force sensor 3 may be replaced with a stroke sensor that detects the amount of depression of the brake pedal 1. Also, the brake pedal O
N and OFF can be determined by the presence or absence of the pedaling force sensor 3, but a switch for ON / OFF detection may be additionally provided. A stroke simulator (not shown) for generating a depressing reaction force of the brake pedal 1 can be freely added.

Reference numeral 5 denotes an electronic control unit for inputting information from various sensors to control the electric actuator 10, 6 a disk rotor, 7 a pad (friction material), 8 a caliper,
Reference numeral 9 denotes a housing fixed to the caliper 8.

The electric actuator 10 includes a brake piston 11, a ball nut 12, which is inserted into a cylinder of a caliper 8 and is prevented from rotating by a pad 7 (or a caliper 8), and a screw shaft 1 screwed to the ball nut 12.
3. An electric motor 14 and a gear set 15 including a pinion 15a and a spur gear 15b as a main element. The power of the motor 14 is transmitted through the gear set 15 to rotate the screw shaft 13, and the screw The rotation of the shaft 13 propels the brake piston 11 to press the pad 7.

The brake device shown in FIG. 1 has a sleeve 1 between a ball nut 12 and an end wall of a brake piston 11.
6 and the spring 17 are interposed, and the thrust is generated in the brake piston 11 after the sleeve 16 compresses the spring 17 and hits the end wall of the brake piston 11. Also, a piston seal 18 is provided to
Is performed by the elastic restoring force of the piston seal 18.

Further, in order to execute the control described later,
A pressure sensor 19 for detecting a pressure applied by the brake piston 11 (this may be a load cell or a strain sensor)
And an encoder 2 for controlling the rotation speed of the motor 14
0 is provided. The encoder 20 is disclosed in Japanese Unexamined Patent Publication No. 9-137.
Although a position sensor as described in No. 841 may be used, clearance control can be performed with a simpler structure by using a motor with a built-in encoder.

In this brake device, the electric actuator 10 is controlled by the electronic control unit 5 so as to generate a braking force corresponding to the output of the pedaling force sensor 3, and the pad 7 is pressed by the brake piston 11 that has been advanced, and The braking of the integrally rotating wheel (not shown) is performed.

When the braking is released, the brake piston 11 returns. The device shown in the figure changes the clearance generated between the pad 7 and the disk rotor 6 by the return of the piston from the accelerator pedal OFF when the accelerator pedal is ON.
Control to make it larger than time is performed.

FIG. 2 shows a flowchart of the control. The steps from the brake pedal ON to the pedal OFF are the same as the control in the conventional electric drive brake device. If advanced behavior control such as antilock is required, a wheel speed sensor, an acceleration sensor (not shown), etc. Is controlled based on this information.

When the brake pedal is confirmed to be OFF, the output of the pressure sensor 19 is taken into the electronic control unit 5, and the position where the output of the pressure sensor 19 becomes zero is set as the zero clearance zero and the brake piston is returned therefrom. The amount (the amount of return of the ball nut 12, ie, the amount of clearance) is controlled. The control is performed by the encoder 20 in the case of the illustrated device.
Is performed by controlling the number of rotations of the motor. Also, if accelerator pedal 2 is ON, clearance is large, OF
F: brake piston 1 so that clearance is small
1 is controlled.

The set clearance between when the accelerator pedal 2 is turned on and when it is turned off may be arbitrarily determined according to vehicle characteristics. For example, clearance at ON, 1.0 mm, OF
A condition such as a clearance of 0.1 mm at the time of F is conceivable, but is not limited thereto. In short, the clearance when the accelerator pedal is ON is the conventional value (generally 0.5 m
m) and the clearance when the accelerator pedal is OFF is smaller than the conventional value, the effect of reducing the drag and the effect of improving the response are both superior to the conventional one.

In the brake device of FIG. 1, after the origin position is set, if the accelerator pedal is turned off in the next step, the reverse rotation of the motor 14 due to the force of the piston seal 18 is stopped halfway (the clearance securing point when the accelerator pedal is turned off). The return of the piston from there is regulated by the sleeve 16, and when the accelerator pedal 2 is turned on, further reverse rotation of the motor 14 is allowed to return the brake piston 11 to the return end point by the force of the piston seal 18, and When the accelerator pedal changes from ON to OFF, the motor 14 is rotated forward and the brake piston 11 is again turned off.
The clearance can be switched by a method of moving forward to a point where the clearance is secured.

The brake device shown in FIG. 1 employs a reversible electric actuator.
1 can be performed by stopping the power supply to the motor 14 and using the force of the piston seal 18 to reduce power consumption. However, the brake piston 11 may be returned by the motor 14.

[0028]

As described above, in the brake device of the present invention, the non-braking clearance between the pad and the rotor is
When the accelerator pedal is ON, it is larger than when the accelerator pedal is OFF, so the clearance when the accelerator pedal is ON is larger than before, and the clearance when the accelerator pedal is OFF is smaller than before, reducing drag and braking responsiveness. Improvements can be achieved at the same time, and the fuel efficiency of the vehicle can be improved, the life of the friction material can be improved, the brake judder can be suppressed, and the safety can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a brake device of the present invention.

FIG. 2 is a diagram showing a control flowchart of the brake device of the above.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 brake pedal 2 accelerator pedal 3 pedal force sensor 4 accelerator switch 5 electronic control device 6 disk rotor 7 pad 8 caliper 9 housing 10 electric actuator 11 brake piston 12 ball nut 13 screw shaft 14 motor 15 gear set 16 sleeve 17 spring 18 piston seal 19 Press sensor 20 Encoder

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 3J058 AA43 AA48 AA53 AA63 AA73 AA78 AA87 BA02 BA16 CC15 CC16 CC17 CC62 CC83 CD24 CD33 DA03 DA32 DA38 DB21 FA01 FA11 FA21

Claims (1)

[Claims] 1. A vehicle brake device in which a friction material is pressed by an electric actuator which receives an operation command from an electronic control device and slides on a rotor.
An OFF detection means is provided, and the control of the electric actuator by the electronic control unit is performed so that the clearance between the rotor and the friction material is larger when the accelerator pedal is ON than when the accelerator pedal is OFF. Vehicle braking device.