KR102758222B1 - Electro-mechanical brake - Google Patents

Abstract

An electromechanical brake is disclosed. According to one aspect of the present invention, an electromechanical brake may be provided, including: a caliper housing provided with a cylinder in which a piston is installed to be retractable so as to pressurize a pad plate; a power conversion unit having a spindle that receives rotational force from an actuator installed in the cylinder to rotate and generate braking force, and a nut coupled to the spindle to convert rotational motion into linear motion to move the piston retractably; and a clutch unit installed in the spindle to rotate together with the spindle in a no-load section of the power conversion unit when driven in a direction of generating braking force, and to store elastic force in a direction of releasing the braking force in a load section.

Description

ELECTRO-MECHANICAL BRAKE

The present invention relates to an electromechanical disc brake, and more specifically, to an electromechanical disc brake that implements braking by converting rotational motion into linear motion.

In general, electro-mechanical brakes are a next-generation brake concept that detects the driver's intention to brake and then uses an electric motor such as a motor to control the braking pressure of the front and rear wheels.

Electromechanical brakes enable all intelligent braking functions, including general braking functions, ABS (anti-lock brake system), ESC (electronic stability control), VDC (vehicle dynamic control), and even automatic braking functions required in future intelligent cruise control devices.

These electromechanical brakes convert rotational power through a motor and a reducer into linear motion to generate an appropriate clamping pressure in the caliper, and perform the functions of service brakes and parking brakes through the clamping pressure. Here, the electromechanical brakes have attempted to improve the performance of the back drive (release) performance by using a linear moving part that converts rotational motion into linear motion, such as a ball screw or a ball in ramp (BIR), or by adding an elastic body (spring) to a ball screw type nut.

However, when installing the above ball-in ramp, there is a limitation that the length must be long in the longitudinal direction of the linear moving part, and there is a problem that the package for fixing the spring when additionally installing the spring is not excellent.

An electromechanical brake according to an embodiment of the present invention not only improves controllability but also improves self-release performance.

According to one aspect of the present invention, an electromechanical brake may be provided, including: a caliper housing provided with a cylinder in which a piston is installed to be retractable so as to pressurize a pad plate; a power conversion unit provided in the cylinder and having a spindle that receives rotational force from an actuator that generates braking force and rotates, and a nut coupled to the spindle and converting the rotational motion into linear motion to move the piston retractably; and a clutch unit provided in the spindle and rotating together with the spindle in a no-load section of the power conversion unit when driven in a direction in which braking force is generated, and storing elastic force in a direction in which braking force is released in a load section.

In addition, the clutch unit may include: a cylindrical outer clutch having a front end that is opened to form an inner receiving space and is rotatably seated on a rear wall of the cylinder, and a rear end that has a hollow formed therein for the spindle to penetrate; an inner clutch that is installed on the spindle to rotate together with the spindle and is arranged in the receiving space so as to be in contact with an inner surface of the outer clutch; and a mechanical energy storage unit that is provided between the outer clutch and the inner clutch and stores elastic force when the inner clutch rotates relative to the outer clutch.

In addition, the mechanical energy storage unit may include an elastic member inserted into a receiving groove formed at a regular interval along the inner surface of the outer clutch; and a pressing member elastically supported by the elastic member and inserted into the receiving groove while compressing the elastic member by pressing.

In addition, a receiving portion for receiving a portion of the pressing member is provided on the outer surface of the inner clutch at a position corresponding to the position where the receiving groove is formed, and the inner clutch can be arranged in the receiving space of the outer clutch such that the receiving portion and the receiving groove face each other.

In addition, the receiving portion may be provided with an inclined surface so that the pressing member compresses the elastic member and slides into the receiving groove when the inner clutch rotates relative to the pressing member.

In addition, when the brake is released or when the actuator fails (power is lost), the pressure member may be moved along the inclined surface of the receiving portion by the elastic restoring force of the elastic member to pressurize the inner clutch, thereby causing the inner clutch to return to the original position and self-release.

In addition, when the elastic member is compressed to the maximum by the pressure member, the end of the pressure member may be provided to protrude from the receiving groove, so that when the inner clutch rotates relative to the outer clutch, the rotation of the inclined surface may be restricted so as not to leave the pressure member.

In addition, the inner clutch and the outer clutch may be arranged to rotate together in the no-load section, and when changing from the no-load section to the load section, the rotation of the outer clutch is prevented by the thrust generated in the spindle, and only the inner clutch may rotate together with the spindle.

In addition, a thrust bearing may be further provided that is installed in the receiving space so as to be interposed between the inner clutch and the outer clutch.

An electromechanical brake according to one embodiment of the present invention can improve the precision of control by implementing independent mechanisms in load and no-load modes.

In addition, the parking force can be automatically released due to the elastic restoring force when the electromechanical brake loses power, which has the effect of ensuring high stability.

In addition, separate auxiliary materials such as ball-in ramps or springs are not assembled in the longitudinal direction of the operating direction of the caliper (brake), and the brake is compactly assembled to the spindle within the cylinder to prevent the overall length of the brake from becoming longer, thereby increasing the design freedom when installing it on a vehicle.

The present invention will be specifically described with reference to the drawings below. However, since these drawings illustrate preferred embodiments of the present invention, the technical idea of the present invention should not be interpreted as being limited to the drawings.
FIG. 1 is a cross-sectional view showing an electromechanical brake according to an embodiment of the present invention.
FIG. 2 is an exploded perspective view showing a clutch unit according to an embodiment of the present invention.
Figure 3 is a partially cut-away perspective view of the assembled clutch unit of Figure 2.
FIG. 4 is a drawing showing the operating state in the no-load section during braking of an electromechanical brake according to an embodiment of the present invention.
Figure 5 is a cross-sectional view showing the operating state of the clutch unit along line V-V' of Figure 4.
FIG. 6 is a drawing showing the operating state in the load section during braking of an electromechanical brake according to an embodiment of the present invention.
Fig. 7 is a cross-sectional view showing the operating state of the clutch unit along line VII-VII' of Fig. 6.
FIG. 8 is a drawing showing a state in which a clutch unit is self-released according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are presented to sufficiently convey the idea of the present invention to those skilled in the art to which the present invention pertains. The present invention is not limited to the embodiments presented herein and may be embodied in other forms. In order to clarify the present invention, the drawings may omit parts that are not related to the description, and may somewhat exaggerate the sizes of components to help understanding.

FIG. 1 is a cross-sectional view showing an electromechanical brake according to an embodiment of the present invention, FIG. 2 is an exploded perspective view showing a clutch unit according to an embodiment of the present invention, and FIG. 3 is a partial cut-away perspective view showing the assembled clutch unit of FIG. 2.

Referring to FIGS. 1 to 3, an electromechanical brake (1) according to the present invention comprises: a carrier (10) on which a pair of pad plates (11, 12) are installed to pressurize a disc (D) that rotates together with a wheel of a vehicle; a caliper housing (20) that is slidably installed on the carrier (10) to operate the pair of pad plates (11, 12); a piston (21) that is installed in the caliper housing (20) so as to be retractable; an actuator (not shown) that provides rotational force for moving the piston (21); a power conversion unit (30) that receives the rotational force transmitted from the actuator, converts it into linear motion, and transmits it to the piston (21) so that the piston (21) moves axially forward and backward; and a power conversion unit (30) that is installed on the spindle (34) of the power conversion unit (30) and rotates together with the spindle (34) in a no-load section when driven in a direction of generating braking force, and stores elastic force in a direction of releasing the braking force in a load section. Includes a clutch unit (100).

A pair of pad plates (11, 12) each have friction pads (13, 14) attached to their inner surfaces. The pair of pad plates (11, 12) are composed of an inner pad plate (11) arranged so that its outer surface is in contact with the tip of a piston (21), and an outer pad plate (12) arranged so that its outer surface is in contact with a finger portion (22) of a caliper housing (20), and are slidably installed on a carrier (10).

The caliper housing (20) includes a finger portion (22) for operating the outer pad plate (12) and a cylinder (23) in which a piston (21) is installed, and is slidably connected to the carrier (10). Accordingly, when braking is applied, the caliper housing (20) slides from the carrier (10) and moves to the right by the reaction force resulting from the movement of the piston (21), and the outer pad plate (12) is pushed toward the disc (D) by the finger portion (22) to pressurize the disc (D).

The piston (21) is provided in a cup shape with one side open and is inserted slidably inside the cylinder (23).

The piston (21) presses the inner pad plate (11) toward the disk (D) by the axial force of the power conversion unit (30) that receives the rotational power of the actuator.

The power conversion unit (30) receives rotational power from an actuator consisting of a motor and a reduction device and presses the piston (21) toward the inner pad plate (11).

The power conversion unit (30) includes a nut (32) that is arranged inside a piston (21) and can move forward and backward, a spindle (34) that receives rotational force from an actuator and rotates to move the nut (32) forward and backward, and a plurality of balls (not shown) interposed between the nut (32) and the spindle (34). This power conversion unit (30) is a linear moving part of a ball screw type that converts rotational motion into linear motion, and since it is a widely known technology, a detailed description will be omitted.

Meanwhile, although not shown in the diagram for the actuator, the actuator may be configured to include a motor and a reduction device having multiple reduction gears, and may be installed on the outside of the caliper housing (20) and coupled with the spindle (34) of the power conversion unit (30). Such an actuator is a known technology used in electromechanical brakes, and may be configured to transmit rotational power to the spindle (34) by grafting an actuator having various reduction gear structures.

The clutch unit (100) may be installed on the spindle (34) of the power conversion unit (30) to implement independent mechanisms in the no-load section and the load section. At this time, the no-load section means the operating section of the nut (32) from the time when the actuator is operated and the spindle (34) receives rotational power until the nut (32) converts the rotational motion according to the rotation of the spindle (34) into linear motion and presses the inner pad plate (11) through the piston (21) to just before coming into contact with the disc (D). In addition, the load section means the section in which the nut (32) is operated so that the inner pad plate (11) is pressed against the disc (D) to generate braking force. That is, the load section is a section in which thrust is generated when the disc (D) is pressed through the pad plates (11, 12), and the no-load section is a section in which no thrust is generated.

More specifically, the clutch unit (100) comprises an outer clutch (110) that is positioned in a cylinder (23) with the front end open, an inner clutch (120) that is installed in a spindle (34) and arranged to come into contact with the inner surface of the outer clutch (110), and a mechanical energy storage unit (130) that stores elastic force when the inner clutch (120) rotates relative to the outer clutch (110).

The outer clutch (110) is provided in a cylindrical shape with a front end that is open to form an inner receiving space (112) and a hollow (114) formed in the rear end to allow a spindle (34) to pass through. As shown, the outer clutch (110) is formed so that its outer surface corresponds to the inner shape of the cylinder (23) and is mounted on the rear wall of the cylinder (23). The outer clutch (110) is provided so as to be rotatable about the spindle (34) within the cylinder (23).

In addition, a receiving groove (113) is formed on the inner surface of the outer clutch (110) so that a mechanical energy storage unit (130) to be described later is placed. A plurality of receiving grooves (113) are provided at regular intervals along the inner surface of the outer clutch (110). As illustrated, four receiving grooves (113) are formed on the outer clutch (110), but this is not limited thereto, and the number may be selectively increased or decreased.

The inner clutch (120) is installed on the spindle (34) so as to rotate together with the spindle (34). The inner clutch (120) is formed to have an approximately circular shape and is placed in the receiving space (112) of the outer clutch (110). At this time, the inner clutch (120) is provided so as to be in close contact with the inner surface of the outer clutch (110). Accordingly, when the inner clutch (120) rotates together with the spindle (34), the outer clutch (110) rotates together due to frictional force.

Meanwhile, a receiving portion (123) may be provided on the outer surface of the inner clutch (120). A plurality of receiving portions (123) are provided at regular intervals along the outer surface of the inner clutch (120). Preferably, the receiving portions (123) are formed to have a number corresponding to the receiving grooves (113). Accordingly, the inner clutch (120) may be installed on the outer clutch (110) such that the receiving grooves (113) and the receiving portions (123) face each other. This receiving portion (123) supports a pressing member (133) of a mechanical energy storage member (130) to be described later, and may be formed to receive a part of the pressing member (133). In addition, when the inner clutch (120) rotates relative to the outer clutch (110), the pressure member (133) may be formed to have an inclined surface (see '123a' of FIG. 5) so that it moves smoothly along the receiving portion (123). As illustrated, the receiving portion (123) may be formed long along the outer circumference of the inner clutch (120) and may be provided to have a tapered cross-sectional shape. The state in which the pressure member (133) is operated by the receiving portion (123) will be described again below.

A mechanical energy storage unit (130) may be provided between the inner clutch (120) and the outer clutch (110). The mechanical energy storage unit (130) is provided to store elastic force when the inner clutch (120) rotates relative to the outer clutch (110). More specifically, the mechanical energy storage unit (130) has an elastic member (131) inserted into a receiving groove (113) formed in the outer clutch (110) and a pressing member (133) elastically supported by the elastic member (131).

The elastic member (131) may be provided as a coil spring. Accordingly, one end of the elastic member (131) is supported by the end of the receiving groove (113) and the other end is supported by the pressure member (133). At this time, one end of the elastic member (131) may be fixed to the receiving groove (113) so that the elastic member (131) is stably provided inside the receiving groove (113) and elastically deformed.

The pressurizing member (133) may be provided in the shape of a ball. In addition, the pressurizing member (133) is provided so that it can be inserted into the receiving groove (113) while compressing the elastic member (131). The pressurizing member (133) is supported by the elastic member (131) while its opposite side is secured and supported in the receiving portion (113) of the inner clutch (120).

Meanwhile, the clutch unit (100) is installed so that the inner clutch (120) rotates together with the spindle (34), and the power conversion unit (30) operates to receive the thrust generated when the inner pad plate (11) is pressed against the disc (D) through the piston (21). Accordingly, the clutch unit (100) further includes a thrust bearing (140) so that the spindle (34) and the inner clutch (120) rotate smoothly by the thrust.

The thrust bearing (140) is installed in the receiving space (112) of the outer clutch (110) so as to be interposed between the inner clutch (120) and the outer clutch (110).

Then, let us explain the state in which the clutch unit operates during braking of the electromechanical brake as described above.

First, referring to FIGS. 4 and 5, when the spindle (34) receives rotational force from an actuator (not shown) and rotates clockwise, the nut (32) converts the rotational force into linear motion and moves forward in the axial direction. Accordingly, the inner pad plate (11) is pressed toward the disk (D) through the piston (21). At this time, in the no-load section where no load is generated before the friction pad (13) of the inner pad plate (11) comes into contact with the disk (D), the inner clutch (120) and the outer clutch (110) rotate together. That is, as the outer surface of the inner clutch (120) and the inner surface of the outer clutch (110) are formed in close contact, the inner clutch (120) and the outer clutch (110) rotate together with the spindle (34) due to the frictional force between the inner clutch (120) and the outer clutch (110). In addition, the elastic member (131) and the pressure member (133) provided between the inner clutch (120) and the outer clutch (110) also move together.

Next, the state in which the clutch unit (100) operates in the load section where the friction pad (13) of the inner pad plate (11) presses the disc (D) will be described with reference to FIGS. 6 and 7.

Referring to FIGS. 6 and 7, as the friction pad (13) of the inner pad plate (11) comes into contact with the disk (D) and pressurizes the disk (D), thrust is transmitted in the direction of arrow T through the power conversion unit (30). That is, the thrust is transmitted to the clutch unit (100) coupled with the spindle (34). Accordingly, the outer clutch (110) is restricted from rotating while in close contact with the rear wall of the cylinder (23) due to the thrust. At this time, the inner clutch (120) is provided to be rotatable together with the spindle (34) by the thrust bearing (140). That is, the inner clutch (120) rotates relative to the outer clutch (110). This is because the thrust becomes greater than the frictional force between the inner clutch (120) and the outer clutch (110), so the rotation of the outer clutch (110) is restricted, and the inner clutch (120) is enabled to rotate by the thrust bearing (140) while being coupled with the spindle (34).

Accordingly, when the inner clutch (120) rotates while the rotation of the outer clutch (110) is restricted, the receiving portion (123) rotates in a direction (clockwise) away from the receiving groove (113). That is, the pressing member (133) slides along the inclined surface (123a) of the receiving portion (123) and moves toward the receiving groove (113). Accordingly, the pressing member (133) compresses the elastic member (131) and moves toward the receiving groove (113), thereby storing elastic force.

Meanwhile, when the elastic member (131) is compressed to the maximum by the pressure member (133), the end of the pressure member (133) is arranged to protrude from the receiving groove (113). Accordingly, when the inner clutch (120) rotates relative to the outer clutch (110), the rotation of the inner clutch (120) can be restricted so that the inclined surface (123a) does not leave the pressure member (133).

Accordingly, the inner clutch (120) and the outer clutch (110) rotate together in the no-load section, and when changing from the no-load section to the loaded section, the rotation of the outer clutch (110) is prevented by the thrust, and only the inner clutch (120) rotates together with the spindle (34), so that the mechanical energy storage unit (130) can store elastic force in the direction of releasing the braking force.

As described above, when the braking is completed and the braking is released, power is applied to the actuator to generate rotational force in the opposite direction to the braking force. That is, when the spindle (34) receives the rotational force and rotates counterclockwise, the nut (32) converts the rotational motion into linear motion and retracts to return to the original position. At this time, as illustrated in FIG. 8, before the nut (32) moves to the no-load section, the inner clutch (120) rotates relative to the outer clutch (110) due to the elastic force stored in the mechanical energy storage unit (130) and returns to the original position. That is, the pressurizing member (133) presses the inner clutch (120) due to the elastic restoring force of the elastic member (131) and moves along the inclined surface (123a) of the receiving unit (123) toward the center of the receiving unit (123). Therefore, when the inner clutch (120) rotates relative to the outer clutch (110) and returns to the original position, the inner clutch (120) and the outer clutch (110) rotate together according to the rotation of the spindle (34).

Meanwhile, in case of failure of the actuator after braking operation, i.e., loss of power, the parking force can be released by rotating the inner clutch (120) in the direction of braking release by the elastic force stored in the mechanical energy storage unit (130). Accordingly, the clutch unit (100) performs a self-release function, thereby ensuring safety performance.

As described above, although the present invention has been described by means of limited embodiments and drawings, the present invention is not limited thereto, and various modifications and variations are possible by those skilled in the art within the technical idea of the present invention and the scope of equivalents of the patent claims to be described below.

1: Electromechanical brake 10: Carrier
20: caliper housing 21: piston
23: Cylinder 30: Power conversion unit
32: Nut 34: Spindle
100: Clutch unit 110: Outer clutch
113 : Receiving home 120 : Inner clutch
123 : Receiving area 123a : Slope
130: Mechanical energy storage unit 131: Elastic member
133: Pressurized member 140: Thrust bearing

Claims (9)

A caliper housing having a cylinder in which a piston is installed retractably to pressurize the pad plate;
A power conversion unit having a spindle that receives rotational power from an actuator installed in the cylinder and generates braking power and rotates, and a nut coupled to the spindle that converts the rotational motion into linear motion to move the piston forward and backward; and
A clutch unit is installed on the spindle and rotates together with the spindle in the no-load section of the power conversion unit when driven in the direction of generating braking force, and stores elastic force in the direction of releasing the braking force in the load section;
The above clutch unit,
A cylindrical outer clutch having a front end that is open to form an inner receiving space and is rotatably seated on the rear wall of the cylinder, and a hollow portion formed in the rear end for the spindle to penetrate through; and
An inner clutch is provided on the spindle so as to rotate together with the spindle and is arranged in the inner receiving space so as to be in contact with the inner surface of the outer clutch;
An electromechanical brake in which the inner clutch and the outer clutch rotate together in the no-load section, and when changing from the no-load section to the load section, the rotation of the outer clutch is prevented by the thrust generated in the spindle, and only the inner clutch is arranged to rotate together with the spindle. In the first paragraph,
The above clutch unit,
An electromechanical brake comprising a mechanical energy storage unit provided between the outer clutch and the inner clutch and storing elastic force when the inner clutch rotates relative to the outer clutch. In the second paragraph,
The above mechanical energy storage unit,
An elastic member inserted into a receiving groove formed at regular intervals along the inner surface of the outer clutch; and
An electromechanical brake comprising: a pressure member that is elastically supported on the elastic member and compresses the elastic member by pressure and is inserted into the receiving groove. In the third paragraph,
On the outer surface of the inner clutch, a receiving portion is provided to receive a portion of the pressing member at a position corresponding to the position where the receiving groove is formed.
An electromechanical brake in which the inner clutch is arranged in the receiving space of the outer clutch so that the receiving portion and the receiving groove face each other. In paragraph 4,
An electromechanical brake in which the above-described receiving portion is provided with an inclined surface so that the pressing member compresses the elastic member and slides into the receiving groove when the inner clutch is rotated relative to the above-described receiving portion. In paragraph 5,
An electromechanical brake in which the pressure member moves along the inclined surface of the receiving portion by the elastic restoring force of the elastic member when the brake is released or when the actuator fails (power is lost), thereby pressurizing the inner clutch, so that the inner clutch returns to the original position and is self-released. In paragraph 5,
An electromechanical brake in which the end of the pressure member is provided to protrude from the receiving groove when the elastic member is compressed to the maximum by the pressure member, so that when the inner clutch rotates relative to the outer clutch, the inclined surface is limited from rotating away from the pressure member. delete In the first paragraph,
An electromechanical brake further comprising a thrust bearing installed in the receiving space so as to be interposed between the inner clutch and the outer clutch.

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