JPH1037993A - Electrically operated brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a brake device small in size and light in weight by adopting an inching mechanism which can continuously function through the combination of two sets of piezoelectric elements, a screwshaft composed of a reversable screw, and two clutch nuts. SOLUTION: An electrically operated brake device is equipped with an inching mechanism to control the movement of a piston 8 by brake pushing pressure occurring in the piston 8. The inching mechanism is provided with a screw shaft 10; the first clutch nut 11 and the second clutch nut 12 arranged rotatably on the screw shaft 10; the first and the second pushing members 22, 23 to compose a cone clutch in cooperation with the clutch nuts 11, 12; the first and the second piezoelectric element 20a, 21a to move the first and the second pushing member 22, 23 in the axial direction of the screw shaft 10; and springs 25, 28 which can move the clutch nut on a side which becomes free when either coneclutch becomes free toward the pushing member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrically actuated braking device, and more particularly to two sets of piezoelectric elements,
The present invention relates to a small and lightweight electrically actuated brake device employing a screw shaft comprising reversible screws and a jogging mechanism which can be operated continuously by combining two clutch nuts.

[0002]

2. Description of the Related Art In recent years, in addition to a hydraulic brake operation circuit, an electric brake device (a so-called by-wire system) for operating a brake by an electric signal has been developed. The electric brake device converts the pedaling force of the brake pedal into an electric signal and activates the brake device by a signal from the electronic control unit.Therefore, the whole system is lighter and smaller than a conventional hydraulic circuit type brake device. There is a feature in that it can be performed, and further, there is an advantage that a system can be easily constructed in executing various controls (anti-skid control, traction control, automatic brake control, etc.) of the brake device.

A brake device using a piezoelectric element as one of such electrically operated brake devices (Japanese Patent Laid-Open No. 61-16 / 1986).
No. 6759) has been proposed. This brake device is characterized by performing a brake control by changing a braking force by a voltage applied to a piezoelectric element, and is expected to be effective in simplifying the configuration of the brake device and reducing the size and weight. However, in the brake device, it is difficult to increase the displacement amount of the piezoelectric element itself.
In addition to the piezoelectric element, a displacement enlarging mechanism for increasing the amount of movement of the brake piston is required, and there have been problems such as a complicated structure and an increase in manufacturing cost.

[0004]

SUMMARY OF THE INVENTION
The present inventor has already proposed a brake operation mechanism that can increase the operation displacement amount without using a special displacement amount enlargement mechanism while using a piezoelectric element (Japanese Patent Laid-Open No. Hei 7 (1995)).
-89420). This brake device has excellent responsiveness, and has great advantages in terms of simplification of the configuration, size reduction and weight reduction, but since only one set of piezoelectric elements is provided in the device, the There is a drawback that it is not possible to continuously increase the braking force smoothly. Accordingly, an object of the present invention is to provide an electrically operated brake device that can continuously exert a smooth and strong braking force by using two sets of piezoelectric elements, and to solve the above-described problems.

[0005]

For this reason, the technical solution adopted by the present invention is to provide a cylinder formed in a caliper of a brake device, a slidable piston disposed in the cylinder, and the piston. A screw shaft for reciprocating toward a disk, a motor for operating the screw shaft, a jogging mechanism provided on the screw shaft for controlling the amount of movement of the piston by a brake pressing force generated on the piston, and the motor And an electronic control device for controlling the inching mechanism, wherein the inching mechanism includes a screw shaft and a first shaft rotatably disposed on the screw shaft.
A clutch nut, a second clutch nut, and first and second clutch nuts which cooperate with the clutch nut to form a cone clutch.
A pressing member, first and second piezoelectric elements for moving the first and second pressing members in the axial direction of the screw shaft, and a clutch on which the cone clutch is released when one of the cone clutches is in a free state. An electrically actuated brake device comprising a spring capable of moving a nut toward a pressing member.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of an electric brake device according to an embodiment of the present invention incorporated in a caliper. 1 in the figure
Is a brake pedal, 2 is a pedaling force sensor, 3 is an electronic control unit (ECU), 4 is a brake caliper, 5 is a pair of disk pads, 6 is a disk arranged between the disk pads, and the individual configurations are known. Using
The description of those detailed configurations will be omitted.

[0007] A cylinder 7 is formed in the caliper 4, and a piston 8 is slidably disposed in the cylinder 7. The piston 8 is formed in a cylindrical shape whose one end is closed. One disc pad 5 is attached to the outer surface on the closed side, and a pressing force sensor 9 is provided on the piston 8. . The pressing force sensor 9 is a sensor for controlling a jogging mechanism that moves in a manner similar to a scaleworm described later. The jogging mechanism is built in the piston 8 and controls the brake pressure in a manner described later.

[Inching Mechanism] The inching mechanism built in the piston 8 has the following configuration. A screw shaft 10 is arranged in the center of the piston 8 so as to coincide with the axis of the piston 8, and one end of the screw shaft 10 is rotatably attached to the center of the bottom of the cylindrical piston. The aforementioned pressing force sensor 9 is disposed between the piston 8 and the piston 8.

The screw shaft 10 is formed as a reversible screw for a first clutch nut 11 and a second clutch nut 12, which will be described later. The gear 13 is mounted so as not to rotate relative thereto, and the screw shaft 10 is provided slidably with respect to the gear 13. The gear 13 is provided rotatably with respect to the caliper 4 via a bearing 14, and the gear 13 is fitted on a worm 17 pivotally supported in the caliper 4, and the worm 17 rotates the motor 18. Attached to the shaft. A cover 15 is disposed outside the gear 13, and a spring 16 is disposed between the cover 15 and the gear 13, and the gear 13 is pressed to the left in the figure by the spring 16.

As shown in FIGS. 2 and 3, around the screw shaft 10, there are first piezoelectric elements 20a and 20b arranged in the horizontal direction in the figure and second piezoelectric elements 21a and 21b arranged in the vertical direction. Two sets of piezoelectric elements are provided, and these piezoelectric elements 20a, 20b, 21a, 21
One end of b is fixed to a caliper. A first pressing member 22 is provided inside the first piezoelectric elements 20a and 20b, and a second pressing member 23 is provided inside the second piezoelectric elements 21a and 21b.
The pressing members 22 and 23 have inclined surfaces 22a and 23a on the left side in FIG.

On the other hand, a first clutch nut 11 and a second clutch nut 12 are screwed to the screw shaft 10, and the first clutch nut 11 and the second clutch nut 12 are respectively connected to the right side in FIG. 1 conical part 11
a, a second conical portion 12a is formed. The first conical portion 11a has an inclined surface 22a formed on the first pressing member 22.
Further, the second conical portion 12a faces the inclined surface 23a formed on the second pressing member 23, and the conical portion 11a,
A so-called cone clutch as described later is formed by the 12a and the inclined surfaces 22a and 23a.

Each of the above-described piezoelectric elements 20a, 20b, 21
When the applied voltage acts on the piezoelectric elements 20a, 2b,
0b, 21a, and 21b expand, and each piezoelectric element 20a, 2b
0b, 21a, first pressing member 2 fixed to 21b
2 and the second pressing member 23 move to the left in the figure, and the inclined surfaces 22a and 23a formed on the pressing member press the first clutch nut 11 and the second clutch nut 12, which will be described later. Can be moved to the middle left.

The spring seat 2 is located near the cylindrical bottom of the piston 8.
4, a disc spring 25, a washer 26, and a bearing 27 are arranged between the spring seat 24 and the first clutch nut 11. The cone member is formed by being pressed by the inclined surface 22a of the pressing member 22. A disc spring 28, a washer 29, and a bearing 30 are also arranged between the second clutch nut 12 and the first pressing member 22,
The second clutch nut 12 is pressed by the biasing force of the disc spring 28 against the inclined surface 23a of the second pressing member 23 to form a cone clutch.

Signals from the pressing force sensor 9, the first and second piezoelectric elements 20a, 20b, 21a, 21b, the brake pedal force sensor 2 and the like are transmitted to the electronic control unit 3, and the electronic control unit 3 The motor 18 or each of the piezoelectric elements 20a, 20b, 21a, 21b is controlled based on the signal.

The operation of the electrically operated brake device according to the above configuration will be described. Since there is no command from the electronic control unit 3 before the brake is actuated, this brake device
It is in the state of. When the driver steps on the brake pedal 1, the pedaling force at this time is detected by the pedaling force sensor 2 and is input to the electronic control unit 3. The electronic control unit 3 drives the motor 18 according to the input signal, rotates the worm 17 and the gear 13, and rotates the screw shaft 10. Here, the first clutch nut 11 and the second clutch nut 12 screwed to the screw shaft 10 are both pressed by the first and second pressing members 22 and 23 by the disc springs 25 and 28, so that they cannot rotate. The screw shaft 10 itself moves to the left in the figure,
Accordingly, the piston 8 also moves, and the disc pad 5 is pressed against the disc 6 to apply a brake.

When the pressing force on the disk 6 by the disk pad 5 reaches a predetermined value, this value is used as a pressing force sensor 9
Is detected and output to the electronic control unit 3. Electronic control unit 3
Then, based on a signal from the pressing force sensor 9, the operation of the motor 18 is stopped, and the first piezoelectric element 20a,
An applied voltage is supplied to 20b. First piezoelectric element 20a, 2
When the applied voltage acts on the first piezoelectric elements 20a, 20b,
b expands and moves the first pressing member 22 fixed to the piezoelectric element to the left in the drawing.

By the movement of the first pressing member 22, the first clutch nut 11 moves to the left in the figure while bending the disc spring 25, and the screw shaft 10 also moves to the left, so that the piston 8 moves. The pressing force of the disk pad 5 can be increased. That is, the first pressing member 22 causes the first
When the clutch nut 11 is pressed, the first clutch nut 11 cannot rotate due to the frictional force between the first clutch nut 11 and the pressing member 22.
3. Since rotation is prevented by the worm 17,
The movement of the pressing member 22 causes the first clutch nut 11 and the screw shaft 10 to move leftward, whereby the disc spring 25 is bent.

At this time, the second clutch nut 12 moves the inclined surface 23 of the second pressing member 23 by the amount of movement of the first pressing member 22.
a, but at the same time, the second clutch nut 12 moves rightward in the figure by this amount while rotating itself by the urging force of the disc spring 28, and again the second pressing member 2
3 is in contact with the inclined surface 23a.

Thereafter, the supply of the applied voltage to the first piezoelectric elements 20a and 20b is stopped, and the applied voltage is supplied to the second piezoelectric elements 21a and 21b almost simultaneously. As a result, at the same time when the first piezoelectric elements 20a and 20b return to the initial state, the second piezoelectric elements 21a and 21b expand and move the second pressing member 23 to the left in the drawing. By the movement of the second pressing member 23, the second clutch nut 12 moves to the left in the figure while bending the disc spring 28, and further the screw shaft 10
Also moves to the left to move the piston 8 and increase the pressing force of the disk pad 5. That is, when the second clutch nut 12 is pressed by the second pressing member 23, the second clutch nut 12 cannot be rotated by the frictional force between the second clutch nut 12 and the second pressing member 23, and the screw shaft 1
The rotation of the second pressing member 23 causes the second clutch nut 12 and the screw shaft 10 to move the disc spring 2
8 moves to the left while flexing.

At this time, the first clutch nut 11 moves the inclined surface 22 of the first pressing member 22 by the amount of movement of the second pressing member 23.
Although the first clutch nut 11 floats at the same time as it floats, the first clutch nut 11 moves rightward in the figure by this amount while rotating by the urging force of the disc spring 25, and returns to the initial state.
Again, it comes into contact with the inclined surface 22a of the first pressing member 22. Thus, the first piezoelectric elements 20a, 20b and the second piezoelectric elements 21a,
An applied voltage is alternately supplied to 21b, and the above operation is repeated to obtain a predetermined brake pressure. Piezoelectric element 20a,
During the above-mentioned brake pressing force increase by 20b, 21a, 21b, the screw shaft 10
The rotation is stopped by 3. Note that such an operation is very similar to the movement of a shading insect, and the present inventor calls this a jogging mechanism.

When the brake is released, the motor 18 is actuated by the pedaling force signal to rotate the worm 17, the gear 13, and the screw shaft 10 in the reverse direction, thereby moving the piston 8 to the right in the drawing. At this time, the first clutch nut 11,
The second clutch nut 12 is provided with pressing members 22 and 23, respectively.
Therefore, only the screw shaft 10 moves rightward in the figure together with the piston 8 while rotating, and the brake is released. A plate 31 is connected to a parking lever (not shown) by a cable. The plate 31 is rotated by pulling the parking lever, and the rotational force is converted into a thrust by a ball ramp mechanism 32. The thrust moves the piston 8 via the sleeve 33, the second pressing member 23, the second clutch nut 12, and the screw shaft 10, and engages the pad 5 with the disk 6.

As described above, the present invention employs a jogging mechanism capable of continuously moving the screw shaft while alternately operating two sets of piezoelectric elements. Therefore, the apparatus is simplified, and the apparatus is small and light. And the brake can be operated smoothly. Further, in the present invention, the braking force can be increased, maintained, and reduced by a control signal from the electronic control device.
Anti-skid control and traction control can also be performed. Further, the piezoelectric element can be controlled as described above by detecting the pressing force on the disk 6 by the disk pad 5 from the load applied to the motor 18 without using the pressing force sensor 9. Further, the inching mechanism is not necessarily limited to the embodiment described above, and any inching mechanism having a similar function can be applied.

[0023]

As described in detail above, the present invention employs a brake operating mechanism (inching mechanism) which can continuously increase the displacement while utilizing two sets of piezoelectric elements.
By incorporating the inching mechanism in the brake device, the device can be simplified, the device can be reduced in size and weight, and the device can be manufactured more compactly and inexpensively. In particular, the responsiveness of the brake pressure control can be improved by employing a jogging mechanism that operates continuously. Further, anti-skid control, traction control, and the like can be easily realized by control by the electronic control device. Excellent operational effects can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an electric brake device as an embodiment according to the present invention, and is a cross-sectional view taken along line AA in FIG. .

FIG. 2 is a sectional view taken along line BB in FIG.

FIG. 3 is a sectional view taken along line CC in FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 brake pedal 2 pedal force sensor 3 electronic control device 4 caliper 5 disk pad 6 disk 7 cylinder 8 piston 9 pressing force sensor 10 screw shaft 11 first clutch nut 12 second clutch nut 17 worm 18 motor 22, 23 first, second Pressing member 25, 28 Disc spring 26, 29 Washer 27, 30 Bearing

Claims (1)

[Claims] 1. A cylinder 7 formed in a caliper 4 of a brake device, a slidable piston 8 arranged in the cylinder 7, and a screw for reciprocating the piston 8 toward a disk 6. A shaft 10, a motor 18 for operating the screw shaft, a jogging mechanism provided on the screw shaft for controlling the amount of movement of the piston 8 by a brake pressing force generated on the piston 8, and the motor and the jogging mechanism. An electronically actuated braking device comprising: an electronic control device 3 for controlling; the inching mechanism comprises: a screw shaft 10; a first clutch nut 11 and a second clutch nut 12 rotatably disposed on the screw shaft 10; First and second pressing members 22 and 23 forming a cone clutch in cooperation with the clutch nuts 11 and 12 First and second piezoelectric elements 20a, 20b, 21a for moving the first and second pressing members 22, 23 in the axial direction of the screw shaft 10,
21b, and a spring 25, 28 capable of moving the clutch nut on the free side toward the pressing member when any of the cone clutches is in a free state. .