Patent Description:
In general, a caliper brake includes a disk rotating together with wheels of a vehicle, a carrier in which a pair of pad plates are installed to move forward and backward to press the disk, and a caliper housing slidably installed on the carrier. The caliper housing is provided with a cylinder in which a piston moves forward and backward by a braking hydraulic pressure.

Such a caliper brake performs a service braking that pressurizes a piston by a braking hydraulic pressure, and also performs a parking brake that pressurizes the piston using a spindle unit that employs additionally an actuator operated by electricity to receive rotational force of a motor to convert a rotational motion into a linear motion. Generally, to reduce a drag phenomenon in which friction pads, that are attached to a pair of pad plates, and a disk continue to rub after braking operation, a method of retracting the piston using a seal member accommodated in a seal groove recessed in a cylinder and a rollback chamber inside the seal groove is used.

A conventional seal member having a ring shape is inserted into an annular seal groove formed on an inner surface of a cylinder of a caliper housing, and is interposed between an inner surface of the cylinder and an outer surface of the piston. The seal member serves to seal the inner surface of the cylinder and the outer surface of the piston to prevent leakage of a braking fluid and to return the piston to its original position. After operation of braking is completed, the seal member is deformed and restored by elasticity thereof, and the piston, which has moved forward, retracts again to return its original position by the elasticity of the seal member. This is called a roll-back.

However, in a conventional caliper brake, elastic deformation of the seal member is completed during a high pressure braking, but a slip in which a piston continuously advances is occurred. Accordingly, the piston does not return smoothly when braking is released, resulting in occurring drag phenomenon in which the disk and the friction pads are rubbed. To resolve the drag phenomenon, elastic deformation movable range of the seal member may be increased by expanding an inclined surface of the seal groove positioned in a forward movement direction of the piston. However, in this case, due to increasing of a required amount of the braking fluid, when the brake pedal is operated an invalid stroke is increased and a pedal feel is reduced. An exemplary disc brake device including an above-mentioned inclined surface in the seal groove is disclosed in document <CIT>.

An aspect of the invention is to provide a caliper brake capable of fully implementing rollback performance of a seal member when braking is released in spite of a high pressure braking.

Another aspect of the invention is to provide a caliper brake capable of preventing a drag phenomenon and improving fuel efficiency of a vehicle by improving rollback performance of a seal member.

Another aspect of the invention is to provide a caliper brake capable of preventing premature deformation of a seal member during a low pressure braking to reduce an amount of braking fluid required, thereby reducing an invalid stroke and improving pedal feel of a driver.

Another aspect of the invention is to provide a caliper brake capable of improving rollback performance of a seal member, but not affecting assembly efficiency or shortening assembly process time.

The invention is set out by the appended set of claims. In accordance with an aspect of the invention, a caliper brake includes a carrier in which a pair of pad plates are installed to move forward and backward toward a disk; a caliper housing slidably installed on the carrier and provided with a cylinder; a piston installed in the cylinder and configured to move forward and backward toward the pair of pad plates by a braking hydraulic pressure; a seal groove formed to be recessed in an annular shape on an inner surface of the cylinder; and a seal member accommodated in the seal groove, the seal member including a front surface located in a forward direction of the piston, a rear face located in a backward direction of the piston, an inner circumferential surface in close contact with an outer circumferential surface of the piston, and an outer circumferential surface in close contact with a seating surface of the seal groove; wherein the front surface is provided with a protrusion from which at least a part thereof protrudes.

A thickness D1 of an outer end of the seal member may be smaller than a thickness D2 of a middle portion of the seal member.

A thickness D3 of an inner end of the seal member may be smaller than the thickness D2 of the middle portion of the seal member.

The seal groove may include the seating surface on which the outer circumferential surface of the seal member is seated, a front braking surface facing the front surface of the seal member, and a front inclined surface inclined from the front braking surface in the forward direction of the piston.

At least a part of the protrusion may be in close contact with the front braking surface when the piston moves forward.

A center part of the protrusion may be in close contact with the front braking surface when the piston moves forward.

The seal groove may be divided into a first space formed below the protrusion, a second space formed above the protrusion, and a third space provided at a rear side of the seal member.

The second space may be filled before the first space by elastic deformation of the seal member when the piston moves forward.

The protrusion may be formed to protrude at regular intervals along a circumferential direction.

The protrusion from which at least a part thereof protrudes may be provided on the rear surface of the seal member.

The seal groove may include a rear braking surface facing the rear surface of the seal member, and a rear inclined surface inclined from the rear braking surface in the backward direction of the piston.

The seal groove may further include a front chamfer inclined at a front portion of the seating surface, and a rear chamfer inclined at a rear portion of the seating surface.

In accordance with another aspect of the invention, a caliper brake includes a carrier in which a pair of pad plates are installed to move forward and backward toward a disk; a caliper housing slidably installed on the carrier and provided with a cylinder; a piston installed in the cylinder and configured to move forward and backward toward the pad plates by a braking hydraulic pressure; a seal member in close contact with an outer surface of the piston and an inner surface of the cylinder, the seal member having a ring-shape; a seal groove formed to be recessed in the inner surface of the cylinder to accommodate the seal member, the seal groove including a seating surface on which an outer circumferential surface of the seal member is seated, a front braking surface facing a front surface of the seal member, and a front inclined surface formed to be inclined in a forward direction of the piston from the front braking surface; and an elastic member accommodated in the seal groove, provided in front of the seal member and interposed between the seal member and the seal groove, the elastic member having a ring-shape; wherein at least a part of the elastic member is in close contact with the front inclined surface when the piston moves forward.

One side of the elastic member may be provided in close contact with the front surface of the seal member, and the other side thereof may be provided in close contact with the front braking surface and the front inclined surface.

The seal groove may include a rear braking surface facing a rear surface of the seal member, and a rear inclined surface inclined from the rear braking surface in a backward direction of the piston.

An outer end of the elastic member may be supported by the front chamfer.

An inner space of the seal groove is divided into a first space positioned in front of the seal member and provided between the elastic member and the piston, a second space positioned in front of the seal member and provided between the elastic member and the seating surface, and a third space positioned at a rear side of the seal member.

The elastic member may be provided in the form of a ring having an inner diameter larger than an outer diameter of the piston, and an outer diameter thereof smaller than an inner diameter of the seal groove.

The embodiments of the invention may provide the caliper brake capable of fully implementing rollback performance of the seal member when braking is released in spite of a high pressure braking.

Further, the embodiments of the invention may provide the caliper brake capable of preventing a drag phenomenon and improving fuel efficiency of the vehicle by improving rollback performance of the seal member.

Further, the embodiments of the invention may provide the caliper brake capable of preventing premature deformation of the seal member during a low pressure braking to reduce an amount of braking fluid required, thereby reducing the invalid stroke and improving pedal feel of a driver.

Further, the embodiments of the invention may provide the caliper brake capable of improving rollback performance of the seal member, but not affecting assembly efficiency or shortening assembly process time.

Hereinafter, the embodiments of the invention will be described in detail with reference to accompanying drawings. It should be understood that the terms used in the specification and the appended claims should not be construed as limited to general and dictionary meanings, but interpreted based on the meanings and concepts corresponding to technical aspects of the invention on the basis of the principle that the inventor is allowed to define terms appropriately for the best explanation. Therefore, the description proposed herein is just a preferable example for the purpose of illustrations only, not intended to limit the scope of the invention, so it should be understood that other equivalents and modifications could be made thereto without departing from the spirit and scope of the invention.

Conventionally, a seal member <NUM> of caliper brake is provided in a ring shape in which an outer circumferential surface <NUM> thereof is in close contact with an inner surface of a cylinder <NUM> and an inner circumferential surface <NUM> thereof is in close contact with an outer surface of a piston <NUM>. At this time, the seal member <NUM> is generally provided in a rectangular cross-section.

The seal member <NUM> seals between the piston <NUM> and the cylinder <NUM> and, at the same time, performs a roll-back operation in which the piston <NUM> advanced by a braking hydraulic pressure returns to its original position when braking is released.

A seal groove <NUM> is formed to be annularly recessed on the inner surface of the cylinder <NUM> to accommodate the seal member <NUM>. In particular, the seal groove <NUM> may include a seating surface <NUM> on which the outer circumferential surface <NUM> of the seal member <NUM> is seated, a front braking surface <NUM> facing a front surface <NUM> of the seal member <NUM>, and a rear braking surface <NUM> facing a rear surface <NUM> of the seal member <NUM>.

Furthermore, the seal groove <NUM> may include a front inclined surface 121a formed to be inclined in a forward direction of the piston <NUM> on the front braking surface <NUM>, and a rear inclined surface 122a formed to be inclined in a backward direction of the piston <NUM> on the rear braking surface <NUM>.

During a braking operation, the piston <NUM> advances toward a pad plate by the braking hydraulic pressure. At this time, the outer circumferential surface <NUM> of the seal member <NUM> is in close contact with the seating surface <NUM> of the seal groove <NUM>, and the inner circumferential surface <NUM> of the seal member <NUM> is elastically deformed in a state in close contact with the outer circumferential surface of the piston <NUM>.

At this time, during a high pressure braking, elastic deformation of the seal member <NUM> is completed in the forward direction of the piston <NUM>, but the piston <NUM> continues to advance, so that a relative slip between the inner circumferential surface of the seal member <NUM> and the outer circumferential surface of the piston <NUM> may occur. Accordingly, when braking is released, the piston <NUM> is not relatively smoothly returned even if the seal member <NUM> returns to its original position, so a drag phenomenon in which friction between a disc and brake pads is generated may occur, thereby causing problems such as a decrease in fuel efficiency of a vehicle.

To solve the problem described above, a method of increasing elastic deformation movable range of the seal member <NUM> by expanding a width of the front inclined surface 111a and expanding a volume of a space positioned in front of the seal member <NUM> is proposed. However, when the seal member <NUM> is elastically deformed, the volume of the space behind the seal member <NUM> also increases, thereby causing an increase in a required amount of a braking fluid. Accordingly, new problems that an invalid stroke of a brake pedal operation is increased and a pedal feel is deteriorated is created.

Therefore, an embodiment of the invention is directed to provide that caliper brake <NUM> that improves rollback performance to reduce the drag phenomenon of the brake, and at the same time to prevent deterioration of pedal feel due to the invalid stroke of the brake pedal during the braking operation.

<FIG> is a cross-sectional view schematically illustrating a caliper brake according to a first embodiment of the invention, and <FIG> is a cross-sectional view schematically showing another type of caliper brake according to the first embodiment of the invention.

Referring to <FIG> and <FIG>, the caliper brake <NUM> according to the first embodiment of the invention includes a disc D rotating together with wheels (not shown) of a vehicle, a carrier (not shown) in which a pair of pad plates <NUM> and <NUM> are installed to move forward and backward so as to press the disc D, a caliper housing <NUM> slidably installed on the carrier (not shown) and provided with a cylinder <NUM>, a piston <NUM> installed in the cylinder <NUM> and provided to advance and retract toward the pad plate <NUM> side by the braking hydraulic pressure, a seal groove <NUM> formed in an annular shape on the inner surface of the cylinder <NUM>, and a seal member <NUM> accommodated in the seal groove <NUM> and in close contact with the outer surface of the piston <NUM> and the inner surface of the cylinder <NUM>.

The caliper brake according to the first embodiment of the invention may be provided as a device provided to implement the braking operation by hydraulic pressure as shown in <FIG>, as well as a device provided to implement a braking operation by other manners. For example, the caliper brake may be provided to implement not only the braking operation by hydraulic pressure, but also an electromechanical braking operation of pressurizing the piston <NUM> with a nut <NUM> by rotating a spindle <NUM> with an actuator <NUM> as shown in <FIG>.

<FIG> is a cross-sectional view illustrating the seal member <NUM> and the seal groove <NUM> according to the first embodiment of the invention by enlarging part A of <FIG> or <FIG>. <FIG> is a perspective view illustrating the seal member <NUM> according to the first embodiment of the invention.

Referring to <FIG> and <FIG>, the seal groove <NUM> is formed to be annularly recessed on the inner surface of the cylinder <NUM> provided in a hollow shape in the caliper housing <NUM>. Furthermore, the seal groove <NUM> accommodates the seal member <NUM>, and the seal member <NUM> is interposed between the seal groove <NUM> and the piston <NUM> to be in close contact.

Particularly, the seal groove <NUM> may include the seating surface <NUM> on which the outer circumferential surface <NUM> of the seal member <NUM> is seated, and the front braking surface <NUM> opposite to the front surface <NUM> of the seal member <NUM>, and a rear braking surface <NUM> opposite to the rear surface <NUM> of the seal member <NUM>.

The seating surface <NUM> may closely support the outer circumferential surface <NUM> of the seal member <NUM> so that the seal member <NUM> may be elastically deformed through friction with the seal member <NUM>. Furthermore, the seating surface <NUM> may be inclined so that an inner diameter thereof increases toward the front braking surface <NUM> side. Accordingly, it prevents the piston <NUM> from being excessively rolled back when the seal member <NUM> is returned, thereby preventing a distance between the piston <NUM> and the pad plate <NUM> from getting farther away.

The front braking surface <NUM> may be bent with angled shape from the seating surface <NUM> to the piston <NUM> side to face the front surface <NUM> of the seal member <NUM>. Herein, the front braking surface <NUM> may normally maintain a state in close contact with at least a part of the protrusion 111a of the seal member <NUM>, and when the piston <NUM> moves forward (during the braking operation), the at least a part of the protrusion 111a is in close contact with the front braking surface <NUM> and elastically deformed. Preferably, a center part of the protrusion 111a or the most protruding part of the protrusion 111a may be in close contact with the front braking surface <NUM> when the piston <NUM> moves forward.

Furthermore, during the braking operation, the front braking surface <NUM> may be in close contact with the front surface <NUM> as well as the protrusion 111a of the seal member <NUM> due to elastic deformation of the seal member <NUM> to limit the movement of the seal member <NUM>. The rear braking surface <NUM> may be bent with angled shape from the seating surface <NUM> to the piston <NUM> side to face the rear surface <NUM> of the seal member <NUM>. Herein, the rear braking surface <NUM> may maintain a spaced apart state from the seal member <NUM> in normal, and when the seal member <NUM> is excessively rolled back by elastic repulsive force while the piston <NUM> moves backward (when the braking is released), the rear braking surface <NUM> may be in close contact with the rear surface <NUM> of the seal member <NUM> to limit movement thereof.

The front braking surface <NUM> and the rear braking surface <NUM> of the seal groove <NUM> may be formed in parallel.

Furthermore, the seal groove <NUM> may further include the front inclined surface 121a formed to be inclined in the forward direction of the piston <NUM> from the front braking surface <NUM> and the rear inclined surface 122a formed to be inclined in the backward direction of the piston <NUM> from the rear braking surface <NUM>.

The front inclined surface 121a may be formed from the front braking surface <NUM>, and may be inclined at about <NUM> degrees in the forward direction of the piston <NUM> from a depth of about half the depth at which the seating surface <NUM> is formed. However, the shape of the front inclined surface 121a is not limited thereto, and various modifications are possible, and the depth and angle of the front inclined surface 121a may be changed according to a rollback amount required, and should be understood in the same way.

The front inclined surface 121a of the seal groove <NUM> may maintain a state in close contact with a part of the protrusion 111a according to the shape and position of the protrusion 111a of the seal member <NUM>. In addition, the front inclined surface 121a is in close contact with not only the protrusion 111a of the seal member <NUM> but also the front surface <NUM> thereof due to elastic deformation of the seal member <NUM> when the piston <NUM> moves forward (during the braking operation) to limit the movement of the seal member <NUM>.

The rear inclined surface 122a may be formed from the rear braking surface <NUM>, and may be inclined at about <NUM> degrees in the backward direction of the piston <NUM> from a depth that is less than half of the depth at which the seating surface <NUM> is formed. However, the shape of the rear inclined surface 122a is not limited thereto, and various modifications are possible, and the depth and angle of the rear inclined surface 122a may be changed according to the required amount of the braking fluid required, and should be understood in the same way.

The seal groove <NUM> may further include a front chamfer 121b that is formed to be inclined at a portion where the front braking surface <NUM> and the seating surface <NUM> are connected, and a rear chamfer 122b that is formed to be inclined at a portion where the rear braking surface <NUM> and the seating surface <NUM> are connected.

The seal member <NUM> provided in a ring shape is accommodated in the seal groove <NUM>, the inner circumferential surface <NUM> thereof may be in close contact with the outer surface of the piston <NUM>, and the outer circumferential surface <NUM> thereof may be in close contact with the inner surface of the seal groove <NUM>.

The seal member <NUM> includes the front surface <NUM> located in the forward direction (hereinafter referred to as a front side) of the piston <NUM> and a rear surface <NUM> located in the backward direction (hereinafter referred to as a rear side) of the piston <NUM>.

The seal member <NUM> may be caught and supported by the front chamfer 121b when moving forward, and may be caught and supported by the rear chamfer 122b when moving backward (See <FIG>).

At least a part of the front surface <NUM> of the seal member <NUM> may be formed to protrude in the forward direction of the piston <NUM>. More specifically, the seal member <NUM> may include the protrusion 111a protruding from the front surface <NUM> in the forward direction of the piston <NUM>, and the protrusion 111a may be formed to protrude in the middle of the front surface <NUM>. Furthermore, the protrusion 111a may be provided in close contact with at least one of the front braking surface <NUM> and the front inclined surface 121a of the seal groove <NUM>.

As shown in the drawings, the protrusion 111a may be formed to protrude from the front surface <NUM> and be rounded. In particular, a protruding edge of the protrusion 111a is formed to be rounded, so that durability loss due to wear is less likely to occur even if the forward and backward movements of the piston <NUM> and the seal member <NUM> are repeated.

Since the protrusion 111a is integrally provided as a part of the body of the seal member <NUM>, assembly efficiency and assembly time of the seal member <NUM> are not affected. In other words, since the protrusion 111a is not formed as a separate member, the assembly efficiency of the conventional seal member is not affected.

However, the front surface <NUM> of the seal member <NUM> may be formed to protrude in various shapes unlike shown in the drawings, a plurality of projections 111a may be formed, and if a portion of the front surface <NUM> is in close contact with the seal groove <NUM> due to the protrusion of the front surface <NUM>, it should be understood in the same way.

As shown in <FIG>, the protrusion 111a is formed to protrude from the front surface <NUM> of the seal member <NUM>, and may be formed to protrude continuously along a circumferential direction thereof.

Furthermore, as shown in <FIG> and <FIG>, the protrusion 111a may be provided to protrude from the front surface <NUM> of the seal member <NUM>, and may include at least one slit 111b in a radial direction. At this time, a spacing between the protrusion 111a and the slit 111b may be variously changed, and should be understood in the same way. As described above, the seal member <NUM> has the protrusion 111a formed in the middle portion, so that the middle portion may have a greater thickness than outer end and inner end. In particularly, the seal member <NUM> may be formed such that a thickness D1 of the outer end is smaller than a thickness D2 of the middle portion, and the seal member <NUM> may be formed such that a thickness D3 of the inner end is smaller than the thickness D2 of the middle portion.

The protrusion 111a of the seal member <NUM> is provided in close contact with at least one of the front braking surface <NUM> and the front inclined surface 121a of the seal groove <NUM>, and because the outer circumferential surface <NUM> of the seal member <NUM> is in close contact with the seating surface <NUM>, an inner space of the seal groove <NUM> may be divided into a first space S1 to a third space S3 by the seal member <NUM>.

Specifically, the inner space of the seal groove <NUM> may be divided into the first space S1 positioned in front of the seal member <NUM> and provided between the seal member <NUM> and the piston <NUM>, the second space S2 positioned in front of the seal member <NUM> and provided between the front braking surface <NUM>, the protrusion 111a and the seating surface <NUM>, and the third space S3 positioned at the rear of the seal member <NUM>. At this time, the first space S1 may have a larger volume than that of the second space S2.

The first space S1 and the second space S2 are partitioned due to the protrusion 111a, which not only prevents premature deformation of the seal member <NUM>, but also ensures additionally a space in which the seal member <NUM> may be deformed to improve rollback performance.

The first and second spaces S1 and S2 are filled with the seal member <NUM> due to elastic deformation of the seal member <NUM> during the braking operation, so that the volume of the first and second spaces S1 and S2 may be decreased, and the volume of the third space S3 may be increased. Conversely, the volume of the first and second spaces S1 and S2 may be increased due to the returning to its original state of the seal member <NUM> when braking is released, and the volume of the third space S3 may be decreased.

<FIG> are cross-sectional views illustrating modified examples of the protrusion 111a of the seal member <NUM> according to the first embodiment of the invention. As shown in <FIG>, the protrusion 111a is formed on the front surface <NUM> of the seal member <NUM>, and may be provided as a protrusion having a rectangular cross-section and protruding from a center to the inner circumferential surface <NUM> thereof.

As shown in <FIG>, the protrusion 111a is formed on the front surface <NUM> of the seal member <NUM>, and may be provided in a shape in which a vertex faces the front braking surface <NUM> and a cross section thereof is formed in a triangular shape.

As shown in <FIG>, the protrusion 111a is formed on the front surface <NUM> of the seal member <NUM>, and may be provided as a trapezoidal protrusion whose width becomes narrower as it protrudes.

As shown in <FIG>, the protrusion 111a is formed on the front surface <NUM> of the seal member <NUM>, and may be provided as a protrusion protruding from the center and having a rectangular cross-section.

As shown in <FIG>, the seal member <NUM> may include not only the protrusions 111a formed on the front surface <NUM>, but also a protrusion 112a protruding toward the rear braking surface <NUM> on the rear surface <NUM>. At this time, the seal member <NUM> may be provided so that the front and the rear sides are symmetrical, which has the effect of improving the assembly efficiency because distinguishing the front and the rear is not necessary when the seal member <NUM> is assembled.

Next, the operation of the seal member <NUM> during the braking operation of the caliper brake <NUM> according to the first embodiment of the invention will be described.

<FIG> are cross-sectional views sequentially illustrating the operation of the seal member <NUM> during the braking operation of the caliper brake <NUM> according to the first embodiment of the invention.

<FIG> may be seen that the piston <NUM> advances from a stationary state as the braking hydraulic pressure changes from a low pressure (about <NUM> to <NUM> bar) to a high pressure (about <NUM> bar), and thus, the seal member <NUM> is elastically deformed gradually.

Specifically, in the stationary state, the protrusion 111a of the seal member <NUM> is maintained in close contact with at least one of the front braking surface <NUM> and the front inclined surface 121a, and the first space S1, the second space S2 and the third space S3 are separated from each other.

During the braking operation, the seal member <NUM> elastically deforms in a state in which the outer and inner circumferential surfaces <NUM> and <NUM> thereof are in close contact with the seating surface <NUM> of the seal groove <NUM> and the outer circumferential surface of the piston <NUM>, respectively. Furthermore, the seal member <NUM> moves to the first and second spaces S1 and S2, and thus the volume of the first and second spaces S1 and S2 decrease. At this time, since the first space S1 has a larger volume than that of the second space S2 due to the front inclined surface 121a, the second space S2 may be filled before the first space S1.

During the high pressure braking, a part of the front surface <NUM> of the seal member <NUM> is completely in close contact with the front braking surface <NUM> of the seal groove <NUM>, and the remaining part thereof moves toward the front inclined surface 121a to fill the second space S2.

The operation while releasing of the braking is performed opposite to the braking operation described above.

Accordingly, the seal member <NUM> according to the first embodiment of the invention may be continuously elastically deformed not only under the low pressure braking but also under the high pressure braking, and prevent a slip phenomenon in which the piston <NUM> moves relative to the seal member <NUM> even at high pressure.

Furthermore, the seal member <NUM> according to the first embodiment of the invention is structurally elastically deformed to fill not only the first space S1 but also the second space S2 during the low pressure braking, so that the volume of the third space S3 does not increase significantly, which prevents an increase in the required amount of the braking fluid during the low pressure braking, thereby reducing the invalid stroke and preventing a decrease in pedal feel.

Hereinafter, the caliper brake <NUM> according to a second embodiment of the invention will be described.

<FIG> is a cross-sectional view illustrating a seal member <NUM>, a seal groove <NUM> and an elastic member <NUM> of a caliper brake <NUM> by enlarging part A of <FIG> or <FIG>.

Referring to <FIG>, <FIG> and <FIG>, the caliper brake <NUM> according to the second embodiment of the invention includes a disc D rotating together with wheels (not shown) of the vehicle, a carrier (not shown) in which the pair of pad plates <NUM> and <NUM> are installed to move forward and backward so as to press the disc D, a caliper housing <NUM> slidably installed on the carrier (not shown) and provided with a cylinder <NUM>, a piston <NUM> installed in the cylinder <NUM> and provided to advance and retract toward the pad plate <NUM> side by the braking hydraulic pressure, a seal groove <NUM> formed in an annular shape on the inner surface of the cylinder <NUM>, a seal member <NUM> accommodated in the seal groove <NUM> and in close contact with an outer surface of the piston <NUM> and an inner surface of the cylinder <NUM>, and an elastic member <NUM> accommodated in the seal groove <NUM> and provided in front of the seal member <NUM> and interposed between the seal member <NUM> and the seal groove <NUM>.

The seal groove <NUM> is formed to be annularly recessed on the inner surface of the cylinder <NUM> provided in a hollow shape in the caliper housing <NUM>. Furthermore, the seal groove <NUM> accommodates the seal member <NUM> and the elastic member <NUM>, the seal member <NUM> is interposed between the seal groove <NUM> and the piston <NUM> to be in close contact, and the elastic member <NUM> is interposed between the seal member <NUM> and the seal groove <NUM> to be in close contact.

Particularly, the seal groove <NUM> may include a seating surface <NUM> on which an outer circumferential surface <NUM> of the seal member <NUM> is seated, and a front braking surface <NUM> facing a front surface <NUM> of the seal member <NUM>, and a rear braking surface <NUM> facing a rear surface <NUM> of the seal member <NUM>.

The seating surface <NUM> may closely support the outer circumferential surface <NUM> of the seal member <NUM> so that the seal member <NUM> may be elastically deformed through friction with the seal member <NUM>. Furthermore, the seating surface <NUM> may be inclined so that an inner diameter thereof increases toward the front braking surface <NUM> side. Accordingly, it prevents the piston <NUM> from being excessively rolled back when the seal member <NUM> is returned, thereby preventing a distance between the piston <NUM> and the pad plate <NUM> from getting farther away. The front braking surface <NUM> may be bent with angled shape from the seating surface <NUM> to the piston <NUM> side to face the front surface <NUM> of the seal member <NUM>. Herein, the front braking surface <NUM> may maintain a state in close contact with at least a part of the elastic member <NUM> in normal, and when the piston <NUM> moves forward (during the braking operation), the at least a part of the elastic member <NUM> is in close contact with the front braking surface <NUM> and elastically deformed. Preferably, a center part of the elastic member <NUM> may be in close contact with the front braking surface <NUM> when the piston <NUM> moves forward.

Furthermore, during the braking operation, the front braking surface <NUM> may be in close contact with the front surface <NUM> of the seal member <NUM> due to elastic deformation of the seal member <NUM> to limit the movement of the seal member <NUM>.

The rear braking surface <NUM> may be bent with angled shape from the seating surface <NUM> to the piston <NUM> side to face the rear surface <NUM> of the seal member <NUM>. Herein, the rear braking surface <NUM> may maintain a spaced apart state from the seal member <NUM> in normal, and when the seal member <NUM> is excessively rolled back by elastic repulsive force while the braking is released, the rear braking surface <NUM> may be in close contact with the rear surface <NUM> of the seal member <NUM> to limit movement thereof.

Furthermore, the seal groove <NUM> may further include a front inclined surface 221a formed to be inclined in the forward direction of the piston <NUM> from the front braking surface <NUM> and a rear inclined surface 222a formed to be inclined in the backward direction of the piston <NUM> from the rear braking surface <NUM>.

The front inclined surface 221a may be formed from the front braking surface <NUM>, and may be inclined at about <NUM> degrees in the forward direction of the piston <NUM> from a depth of about half the depth at which the seating surface <NUM> is formed. However, the shape of the front inclined surface 221a is not limited thereto, and various modifications are possible, and the depth and angle of the front inclined surface 221a may be changed according to the rollback amount required, and should be understood in the same way.

The front inclined surface 221a of the seal groove <NUM> may maintain a state in close contact with at least a part of the elastic member <NUM>, and when the piston <NUM> moves forward the front inclined surface 221a is in close contact with the front surface <NUM> of the seal member <NUM> due to elastic deformation of the seal member <NUM> to limit the movement of the seal member <NUM>.

The rear inclined surface 222a may be formed from the rear braking surface <NUM>, and may be inclined at about <NUM> degrees in the backward direction of the piston <NUM> from a depth that is less than half of the depth at which the seating surface <NUM> is formed. However, the shape of the rear inclined surface 222a is not limited thereto, and various modifications are possible, and the depth and angle of the rear inclined surface 222a may be changed according to the required amount of the braking fluid required, and should be understood in the same way.

The seal groove <NUM> may further include a front chamfer 221b that is formed to be inclined at a portion where the front braking surface <NUM> and the seating surface <NUM> are connected, and a rear chamfer 122b that is formed to be inclined at a portion where the rear braking surface <NUM> and the seating surface <NUM> are connected.

The seal member <NUM> is accommodated in the seal groove <NUM>, and the inner circumferential surface thereof may be in close contact with the outer surface of the piston <NUM>, and the outer circumferential surface thereof may be provided in a ring shape in close contact with the inner surface of the seal groove <NUM>.

The seal member <NUM> includes the front surface <NUM> located in the forward direction of the piston <NUM> and the rear surface <NUM> located in the backward direction of the piston <NUM>.

The seal member <NUM> may be caught and supported by the front chamfer 221b when moving forward, and may be caught and supported by the rear chamfer 222b when moving backward (See <FIG>).

The front surface <NUM> and the rear surface <NUM> of the seal member <NUM> may be provided to be flat and parallel to the front braking surface <NUM> and the rear braking surface <NUM> of the seal groove <NUM>. Furthermore, the cross-section of the seal member <NUM> may be preferably provided in a rectangular shape.

The elastic member <NUM> may be provided in a ring shape having an inner diameter thereof larger than the outer circumferential surface <NUM> of the piston <NUM> and smaller than an inner diameter of the seating surface <NUM> side of the seal groove <NUM>. Furthermore, the elastic member <NUM> may be made of, for example, a polymer material such as a fluorine rubber or a silicone rubber.

One side of the elastic member <NUM> may be provided in close contact with the front surface <NUM> of the seal member <NUM>, and the other side thereof may be provided in close contact with at least one of the front braking surface <NUM> and the front inclined surface 221a of the seal groove <NUM>.

Furthermore, at least a part of the outer circumferential surface of the elastic member <NUM> may be supported by the front chamfer 221b. Specifically, a front side of the outer circumferential surface of the elastic member <NUM> may be supported by the front chamfer 221b so that the elastic member <NUM> may be maintained in a spaced apart state without being in close contact with the seating surface <NUM>.

The cross-section of the elastic member <NUM> may be formed in various shapes different from those shown in the drawings, and various deformations such as an oval and hexagonal cross-section are possible, and if the elastic member <NUM> is interposed between the seal member <NUM> and the seal groove <NUM> and is in close contact, it should be understood in the same way.

Since one side of the elastic member <NUM> is provided in close contact with the front surface <NUM> of the seal member <NUM> and the other side thereof is provided in close contact with at least one of the front braking surface <NUM> and the front inclined surface 221a of the seal groove <NUM>, an inner space of the seal groove <NUM> is divided into a first space S1 to a third space S3. Specifically, the inner space of the seal groove <NUM> is divided into the first space S1 positioned in front of the seal member <NUM> and provided between the elastic member <NUM> and the piston <NUM>, the second space S2 positioned in front of the seal member <NUM> and provided between the elastic member <NUM> and a horizontal surface, and the third space S3 positioned at the rear of the seal member <NUM>. At this time, the first space S1 may have a larger volume than that of the second space S2.

The volume of the first and second spaces S1 and S2 may be decreased due to elastic deformation of the elastic member <NUM> and the seal member <NUM> during the braking operation, and the volume of the third space S3 may be increased. Conversely, the volume of the first and second spaces S1 and S2 may be increased due to the returning to their original state of the elastic member <NUM> and the seal member <NUM> when braking is released, and the volume of the third space S3 may be decreased.

Next, operations of the elastic member <NUM> and the seal member <NUM> during the braking operation of the caliper brake <NUM> according to the second embodiment of the invention will be described.

<FIG> are cross-sectional views sequentially illustrating the operations of the elastic member <NUM> and the seal member <NUM> during the braking operation of the caliper brake <NUM> according to the second embodiment of the invention.

<FIG> may be seen that the piston <NUM> advances from a stationary state as the braking hydraulic pressure changes from a low pressure (about <NUM> to <NUM> bar) to a high pressure (about <NUM> bar), and thus, the elastic member <NUM> and the seal member <NUM> is elastically deformed gradually.

Specifically, in the stationary state, the elastic member <NUM> is maintained in close contact with at least one of the front braking surface <NUM> and the front inclined surface 221a, and the first space S1, the second space S2 and the third space S3 are maintained in a separated state, respectively.

During the braking operation, the seal member <NUM> elastically deforms in a state in which the outer and inner circumferential surfaces <NUM> and <NUM> thereof are in close contact with the seating surface <NUM> of the seal groove <NUM> and the outer circumferential surface <NUM> of the piston <NUM>, respectively. Furthermore, the elastic member <NUM> and the seal member <NUM> move to the first and second spaces S1 and S2, and thus the volume of the first and second spaces S1 and S2 decrease. At this time, since the first space S1 has a larger volume than that of the second space S2 due to the front inclined surface, the second space S2 may be filled before the first space S1.

During the high pressure braking, a part of the front surface <NUM> of the seal member <NUM> is completely in close contact with the front braking surface <NUM> of the seal groove <NUM>, and the remaining part thereof moves toward the front inclined surface 221a to fill the second space S2.

Accordingly, the seal member <NUM> according to the second embodiment of the invention may be continuously elastically deformed not only under the low pressure braking but also under the high pressure braking, and prevent a slip phenomenon in which the piston <NUM> moves relative to the seal member <NUM> even at high pressure.

Furthermore, the seal member <NUM> according to the second embodiment of the invention is structurally elastically deformed to fill not only the first space S1 but also the second space S2 during the low pressure braking, so that the volume of the third space S3 does not increase significantly, which prevents an increase in the required amount of the braking fluid during the low pressure braking, thereby reducing the invalid stroke and preventing a decrease in pedal feel.

<FIG> is a graph illustrating displacements of the piston <NUM> and the seal member <NUM> of the caliper brake <NUM> of according to first and second embodiments of the invention and a conventional caliper brake <NUM>, according to a change in the braking hydraulic pressure.

<FIG> shows a displacement x1 of the seal member of the first embodiment, a displacement x2 of the seal member of the second embodiment, a displacement x3 of the conventional seal member, a displacement y1 of the piston of the first embodiment, a displacement y2 of the piston of the second embodiment, and a displacement y3 of the conventional piston.

As shown in <FIG>, looking at the displacements y3 and x3 of the piston <NUM> and the seal member <NUM> of the conventional caliper brake according to the change in the braking hydraulic pressure, as the braking hydraulic pressure of <NUM> bar is applied (<NUM> second to <NUM> seconds), the displacement y3 of the piston increases linearly and finally the displacement y3 reaches <NUM>. At this time, the displacement x3 of the seal member starts from <NUM> and increases linearly, and first reaches about <NUM> (about <NUM> seconds), so no further displacement occurs and the same displacement is maintained (<NUM> seconds to <NUM> seconds). This is because the elastic deformation of the seal member <NUM> is not accomplished according to the displacement of the piston <NUM> during the high pressure braking, so that the relative slip occurs between the piston <NUM> and the seal member <NUM> (<NUM> seconds to <NUM> seconds).

Furthermore, as the braking hydraulic pressure is released (<NUM> to <NUM> seconds), the displacement y3 of the piston gradually returns to its original position and finally the displacement y3 reaches about <NUM>. In addition, the displacement x3 of the seal member is maintained at the same displacement (<NUM> seconds to <NUM> seconds), then gradually returns to its original position, and finally the displacement X3 reaches about <NUM>. As described above, the relative slip occurs between the piston <NUM> and the seal member <NUM> during the high pressure braking, so that the seal member <NUM> may not fully implement a rollback function, and as a result, the piston <NUM> and the seal member <NUM> may not return to its original positions.

This may cause a fine drag between the brake pad and the disk D due to a non-return of the piston <NUM>, and also cause a decrease in fuel efficiency due to a residual braking torque.

In contrast, looking at the displacements y1, y2, x1 and x3 of the piston and the seal member of the caliper brakes <NUM> and <NUM> according to the first and second embodiments of the invention according to the change in the braking hydraulic pressure, as the braking hydraulic pressure of <NUM> bar is applied, the displacements y1 and y2 of the piston increases linearly and finally the displacements y1 and y2 reach <NUM> (<NUM> second to <NUM> seconds). At this time, the displacements x1 and x2 of the seal member starts from <NUM> and increases linearly to reach about <NUM> (<NUM> second to <NUM> seconds). This is because the elastic deformation of the seal member <NUM> is continuously performed according to the displacement of the piston during the high pressure braking, so that the relative slip does not occur between the piston <NUM> and the seal member <NUM>.

Furthermore, as the braking hydraulic pressure is released, the displacements y1 and y2 of the piston gradually returns to their original position and finally the displacements y1 and y2 reach <NUM> (<NUM> seconds to <NUM> seconds). Furthermore, the displacements x1 and x2 of the seal member gradually returns to their original position and finally the displacements x1 and x2 reach about <NUM>. As described above, in the embodiments of the invention, the relative slip does not occur between the piston <NUM> and the seal member <NUM> during the high pressure braking, so that the seal member <NUM> implements the rollback function, and as a result, the piston <NUM> and the seal member <NUM> may return to their original positions.

Hereinafter, a change in the distance between the pad plate and the piston according to the first embodiment of the invention and the pad plate and the piston according to the conventional caliper brake under different braking hydraulic conditions will be described.

<FIG> is a graph illustrating positions of the piston with respect to the pad plate according to the change in the brake hydraulic pressure after the braking operations of the conventional caliper brake and the caliper brake according to the first embodiment of the invention.

<FIG> shows that a clearance Z1 between the pad plate and the piston of first embodiment of the invention and a clearance Z2 between the pad plate and the piston of the conventional caliper brake in different braking hydraulic conditions (<NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> bar).

Referring to <FIG>, it may be seen that the clearance Z2 between the pad plate and the piston of the conventional caliper brake is maintained at a certain level (about <NUM>) in a low pressure region (<NUM>, <NUM> bar), but decreases sharply (up to about <NUM>) as the clearance z2 between the piston and the piston goes through a middle pressure region (<NUM>, <NUM> bar) and toward a high pressure region (<NUM>, <NUM> bar). This is because the slip occurs between the piston and the seal member as the braking hydraulic pressure goes to the high pressure region, so that the seal member does not smoothly roll back the piston. Accordingly, in the conventional seal member, the clearance Z2 between the pad plate and the piston is decreased after the braking operation due to the slip phenomenon as the braking hydraulic pressure increases to a high pressure, thereby causing drag, which generates a decrease in fuel efficiency and a decrease in durability of the brake pad.

Meanwhile, it may be seen that the clearance Z1 between the pad plate and the piston according to first embodiment of the invention is maintained within a certain value (about <NUM> ~ <NUM>) even when going from the low pressure region (<NUM>, <NUM> bar) to the high pressure region (<NUM>, <NUM> bar) through the middle pressure region (<NUM>, <NUM> bar). This shows that even when the braking hydraulic pressure changes from the low pressure region to the high pressure region, the slip does not occur between the piston and the seal member, so that the seal member may smoothly roll back the piston.

In other words, the clearance Z2 between the pad plate and the piston of the conventional caliper brake has a change width of <NUM> from about <NUM> to about <NUM> from low pressure to high pressure, whereas the clearance Z1 between the pad plate and the piston of first embodiment of the invention has a change width of <NUM> from about <NUM> to about <NUM> from low pressure to high pressure, so that the caliper brake of first embodiment of the invention may expect constant rollback performance and braking performance from the low pressure region to the high pressure region.

Therefore, the caliper brake according to first embodiment of the invention has the advantage of being able to expect constant braking performance even under the braking hydraulic conditions from the low pressure region to the high pressure region, and furthermore, prevent the deterioration of fuel efficiency and durability due to the drag phenomenon.

Claim 1:
A caliper brake (<NUM>), comprising:
a carrier in which a pair of pad plates (<NUM>, <NUM>) are installed to move forward and backward toward a disk (D);
a caliper housing (<NUM>) slidably installed on the carrier and provided with a cylinder (<NUM>);
a piston (<NUM>) installed in the cylinder (<NUM>) and configured to move forward and backward toward the pair of pad plates (<NUM>, <NUM>) by a braking hydraulic pressure;
a seal groove (<NUM>) formed to be recessed in an annular shape on an inner surface of the cylinder (<NUM>); and
a seal member (<NUM>) accommodated in the seal groove (<NUM>), the seal member (<NUM>) including a front surface (<NUM>) located in a forward direction of the piston (<NUM>), a rear surface (<NUM>) located in a backward direction of the piston (<NUM>), an inner circumferential surface (<NUM>) in close contact with an outer circumferential surface of the piston (<NUM>), and an outer circumferential surface (<NUM>) in close contact with a seating surface (<NUM>) of the seal groove (<NUM>);
characterized in that
the front surface (<NUM>) is provided with an integral protrusion (111a) from which at least a part thereof protrudes.