Patent ID: 12233828

MODES OF THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings in order for those skilled in the art to easily perform the present invention. The present invention may be implemented in several different forms and is not limited to the embodiments described herein. Parts irrelevant to descriptions are omitted in the drawings in order to clearly explain the present invention, and the same or similar parts are denoted by the same reference numerals throughout this specification.

It should be further understood that the terms “comprise,” “comprising,” “include,” and/or “including,” when used herein, specify the presence of stated features, numbers, steps, operations, elements, and/or components but do not preclude the presence or addition of one or more other features, numbers, steps, operations, elements, components, and/or groups thereof.

InFIG.1, a perspective view of an actuator of an electric parking brake according to one embodiment of the present invention is illustrated, and inFIG.2, a view of a housing of the actuator of the electric parking brake according to one embodiment of the present invention is illustrated, wherein a part of the housing is transparently shown and another part thereof is cut.FIG.3is a view illustrating a state in which an upper housing of the actuator of the electric parking brake according to one embodiment of the present invention is removed when viewed from above. In addition,FIG.4is a perspective view of a state, in which the housing is removed and a driving shaft control unit is separated from the actuator of the electric parking brake according to one embodiment of the present invention.

An actuator1of the electric parking brake according to one embodiment of the present invention is a brake which is installed in a vehicle and electronically provides a braking force required for parking of the vehicle. The actuator1of the electric parking brake according to one embodiment of the present invention provides a self-locking structure which effectively prevents reverse gear rotation due to a reverse rotation torque after braking performed by the electric parking brake. The actuator1of the electric parking brake according to one embodiment of the present invention may be applied to a large commercial vehicle such as a truck.

Referring toFIGS.1to4, the actuator1of the electric parking brake according to one embodiment of the present invention may include a housing10, a driving unit20, a first gear unit30, a second gear unit40, a speed reduction unit50, and a driving shaft control unit60.

The actuator1of the electric parking brake according to one embodiment of the present invention generates power required for a parking brake using the driving unit20in a case in which a braking force is required for parking the vehicle in a state in which the actuator1of the electric parking brake is installed in the vehicle. A rotational force generated by the driving unit20is transmitted to the speed reduction unit50through the first gear unit30and the second gear unit40. In addition, the speed reduction unit50may transmit the rotational force to a conversion unit (not shown) which converts the rotational force into linear movement to press a disc of the vehicle to generate a braking force.

In this case, the conversion unit may include various devices which convert rotation movement into linear movement. For example, the conversion unit may include a spindle unit. Meanwhile, one embodiment of the present invention is applied to a large commercial vehicle, in which a large braking force may be transmitted as a torque in a reverse direction during parking in order to effectively prevent reverse gear rotation due to a reverse rotation torque. In consideration of this, the conversion unit may also include a ball ramp, which is widely used in an electric parking brake of the large commercial vehicle because efficiency of the ball ramp is relatively higher than that of a spindle, when the present invention is applied.

When a reverse direction torque is generated after braking, the reverse direction torque is transmitted to the driving unit20through the speed reduction unit50, the second gear unit40, and the first gear unit30, and when a driving shaft21of the driving unit20is rotated due to the reverse direction torque, there is a problem of loss of the braking force. In the actuator1of the electric parking brake according to one embodiment of the present invention, the driving shaft control unit60prevents reverse rotation, which is due to a reverse rotation torque, of the driving shaft21of the driving unit20to solve such a problem.

Hereinafter, the housing10, the driving unit20, the first gear unit30, the second gear unit40, the speed reduction unit50, and the driving shaft control unit60included in the actuator1of the electric parking brake according to one embodiment of the present invention will be described in more detail.

The housing10accommodates components such as the driving unit20, the first gear unit30, the second gear unit40, the speed reduction unit50, and the driving shaft control unit60. That is, the housing10provides a space in which the driving unit20, the first gear unit30, the second gear unit40, the speed reduction unit50, and the driving shaft control unit60are disposed. As shown inFIG.1, the housing10may include an upper housing11and a lower housing12.

In addition, as shown inFIG.3, one or more fixing grooves121may be formed in a side surface of the lower housing12constituting the space, in which the second gear unit40and the speed reduction unit50are disposed, in a longitudinal direction. As will be described below, protrusions521of a ring gear52of the speed reduction unit50may be inserted into the fixing grooves121to fix the ring gear52.

Meanwhile, the housing10may be installed in the vehicle and may also provide an interface for connecting the actuator1of the electric parking brake according to one embodiment of the present invention and other components of the vehicle.

The driving unit20generates a rotational force. In one embodiment of the present invention, the driving unit20may include a motor. The driving unit20may be controlled by an electronic control unit (ECU) of the vehicle and provide the rotational force for generating a braking force required for parking the vehicle. Accordingly, the vehicle, in which the actuator1of the electric parking brake according to one embodiment of the present invention is installed, may electrically generate the braking force required for parking without complex hydraulic components.

The first gear unit30receives the rotational force from the driving unit20. Specifically, the first gear unit30primarily receives the rotational force of the driving unit20and transmits the rotational force to the second gear unit40. In one embodiment of the present invention, the first gear unit30may include a first worm31coupled to an output shaft of the driving unit20, a first worm wheel32engaged with the first worm31and rotated, a transmission shaft33connected to the first worm wheel32and rotated, and a second worm34disposed on the transmission shaft33, engaged with the second gear unit40, and rotated.

The second gear unit40receives the rotational force from the first gear unit30and rotates. The second gear unit40may transmit the rotational force to the speed reduction unit50. In other words, the second gear unit40may be connected to the speed reduction unit50to transmit the rotational force received from the first gear unit30to the speed reduction unit50, the speed reduction unit50may transmit the rotational force to the conversion unit, and the conversion unit may convert the rotational force into linear movement to generate a braking force required for parking.

Referring toFIGS.5and6, in one embodiment of the present invention, the second gear unit40may include a rotation shaft41, an inner gear42, and an outer gear43.

The rotation shaft41receives a rotational force from the inner gear42to rotate and transmits the rotational force to other components. In one embodiment of the present invention, the rotation shaft41may transmit the rotational force of the second gear unit40to the speed reduction unit50.

The inner gear42is coupled to the rotation shaft41and transmits the rotational force, which is transmitted through the outer gear43, of the first gear unit30to the rotation shaft41. An outer circumferential surface of the inner gear42may be coupled to an inner circumferential surface of the outer gear43.

More specifically, the inner gear42may include a small diameter unit421and a large diameter unit422.

The small diameter unit421is a portion through which a coupling hole4211coupled to the rotation shaft41is formed to pass in a longitudinal direction, one end portion of the small diameter unit421is connected to the large diameter unit422, and gear teeth4212are formed on an outer circumferential surface on a predetermined section of the other end portion. In one embodiment of the present invention, the gear teeth4212of the small diameter unit421are engaged with a plurality of planetary gears51of the speed reduction unit50to serve as a sun gear.

The large diameter unit422is formed so that a diameter of the large diameter unit422increases from an outer circumferential surface of the one end portion of the small diameter unit421. The large diameter unit422is coupled to the outer gear43and transmits the rotational force transmitted through the outer gear43to the small diameter unit421. In addition, in one embodiment of the present invention, coupling grooves4221for being stably coupled to the outer gear43are formed in an outer circumferential surface of the large diameter unit422. Specifically, the coupling grooves4221may be formed along the outer circumferential surface of the large diameter unit422to be recessed and spaced apart from each other at predetermined intervals and may be formed in parallel in an upper end and a lower end along the outer circumferential surface of the large diameter unit422.

The outer gear43may be formed as a gear having a ring shape in which the inner circumferential surface of the outer gear43is coupled to the inner gear42, and gear teeth432engaged with the first gear—unit30are provided on an outer circumferential surface of the outer gear43. As the gear teeth432formed on the outer circumferential surface of the outer gear43are engaged with the second worm34of the first gear unit30, the outer gear43receives the rotational force of the first gear unit30.

The outer gear43may be formed in the ring shape and include coupling protrusions431on the inner circumferential surface thereof. The coupling protrusions431are formed to correspond to the coupling grooves4221formed in the outer circumferential surface of the large diameter unit422of the inner gear42and allow the outer gear43and the inner gear42to be stably coupled.

In one embodiment of the present invention, the inner gear42and the outer gear43may be integrally formed in an insertion-injection manner or the like. In this case, the coupling grooves4221of the inner gear42and the coupling protrusions431of the outer gear43help stable coupling of the inner gear42and the outer gear43.

The speed reduction unit50increases a rotational torque transmitted by the second gear unit40. The speed reduction unit50increases the rotational force generated by the driving unit20and transmitted to the conversion unit through the first gear unit30and the second gear unit40to allow a sufficient force for parking to be generated in the conversion unit.

Referring toFIGS.5and7, the speed reduction unit50may include the plurality of planetary gears51, the ring gear52, and a carrier53.

The plurality of planetary gears51are disposed to be engaged with the gear teeth4212provided on the outer circumferential surface of the small diameter unit421of the inner gear42. That is, the plurality of planetary gears51are disposed to be engaged with the small diameter unit421of the inner gear42, wherein the small diameter unit421serves as a sun gear.

The ring gear52is fixedly disposed with respect to the rotation shaft41as gear teeth522disposed on an inner circumferential surface of the ring gear52are engaged with the plurality of planetary gears51. Specifically, the ring gear52includes the protrusions521disposed on an outer circumferential surface thereof, and the ring gear52may be fixedly disposed with respect to the rotation shaft41as the protrusions521are disposed to be inserted into the fixing grooves121formed in the lower housing12.

The carrier53is coupled to the rotation shaft41and rotation shafts511of the plurality of planetary gears51. To this end, an insertion groove531, into which the rotation shaft41is inserted, may be formed in one surface of the carrier53. The carrier53is coupled to the rotation shaft41and the rotation shafts511of the plurality of planetary gears51and rotated so as to output an amplified rotational force. In this case, the carrier53may output the amplified rotational force to the conversion unit.

The driving shaft control unit60is disposed on the driving shaft21to provide a degree of rotational freedom to the driving shaft21for braking and fixes the driving shaft21to prevent reverse rotation, which is due to a reverse rotation torque, of the driving shaft21when the braking is ended. According to one embodiment of the present invention, the driving shaft control unit60may prevent the reverse rotation of the driving shaft21due to the reverse rotation torque, and thus loss of the braking force due to the reverse rotation torque after parking can be prevented.

The driving shaft control unit60is disposed at one side of the driving unit20. In one embodiment of the present invention, the driving shaft21of the driving unit20protrudes from one end and the other end of the driving unit20, the first gear unit30is disposed on the one end, and the driving shaft control unit60is disposed at a side of the other end. Through such an arrangement, a space, in which the first gear unit30and the second gear unit40are disposed, of the one end of the driving shaft21may be effectively secured.

In one embodiment of the present invention, the driving shaft control unit60may include a solenoid locking device capable of fixing the driving shaft21. In this case, the solenoid locking device may operate in a manner of providing a degree of rotational freedom to the driving shaft21when a current is applied and fixing the driving shaft21when a current is not applied.

More specifically, the driving shaft control unit60may include a solenoid61, which allows or restricts rotation of the driving shaft21according to whether a current is supplied, and a wire62through which the current is applied to the solenoid61.

In addition, the solenoid locking device may be formed as one of various types, and the driving shaft control unit60may include an arbitrary solenoid locking device applied to restrict rotation of a conventional rotation shaft.

While the embodiments of the present invention have been described above, the spirit of the present invention is not limited to the embodiments proposed in this specification, and other embodiments may be easily suggested by adding, changing, and removing components by those skilled in the art and will fall within the spiritual range of the present invention.