Patent Publication Number: US-2022235838-A1

Title: Brake apparatus for vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit under 35 U.S.C. § 119(a) of priority to Korean Patent Application No. 10-2021-0011496 filed on Jan. 27, 2021 in the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference for all purposes. 
     BACKGROUND 
     Technical Field 
     Exemplary embodiments of the present disclosure relate to a brake apparatus for a vehicle, and more particularly, to a brake apparatus for a vehicle, which can withstand a heavy load during operation and can be mass-produced through mold manufacturing. 
     Discussion of the Background 
     In general, in an electronic parking brake (EPB) of a vehicle, an actuator device converts a rotational force of a driving motor into a linear motion by using a screw and a nut mechanism together with a gear module unit and presses a piston. The pressed piston presses a brake pad, which is a friction material, to a wheel disc, thereby generating a braking force. 
     The gear module unit of the actuator device applied to the electronic parking brake in the related art includes a worm shaft connected to a rotating shaft of the driving motor and a worm wheel engaged with a first worm shaft. A gear of the worm wheel is a crossed helical gear having a flat cross-section or an enveloping gear having a concave cross-section. 
     However, the gear of the worm wheel that is the crossed helical gear having a flat cross-section can be mass-produced through mold manufacturing, but has low rigidity and durability low because a contact area of the worm shaft with the gear is relatively small. Furthermore, the gear of the worm wheel that is the enveloping gear having a concave cross-section has high rigidity and durability because the contact area of the worm shaft with the gear is relatively large, but mass production of the gear is difficult because of difficulty in mold manufacturing. Therefore, there is a need for solving the above problems. 
     The background art of the present disclosure is disclosed in Korean Patent No. 10-1041553 (registered on Jun. 8, 2011 and entitled “Electronic Parking Brake Actuator”). 
     SUMMARY 
     The present disclosure has been made to solve the above problems, and an object of the present disclosure is to provide a brake apparatus for a vehicle, which can withstand a heavy load during operation and can be mass-produced through mold manufacturing. 
     In order to solve the above problems, a brake apparatus for a vehicle in accordance with the present disclosure includes: a pair of brake pads that are disposed to face each other on a caliper body and disposed on two sides of a wheel disc, respectively; a first worm shaft part that is connected to a motor part and located inside a housing part; a first worm wheel part that is located inside the housing part, is engaged with the first worm shaft part, and rotates with rotation of the first worm shaft part; a second worm shaft part that is located inside the housing part, is connected to the first worm wheel part, and rotates together with the first worm wheel part when the first worm wheel part rotates; a second worm wheel part that is engaged with the second worm shaft part, and includes a plurality of second gear teeth each including a second enveloping gear tooth portion having a second inclined portion that increases in height toward one end side from a center portion and a second helical gear tooth portion having a constant height from the center portion to another end side; and a linear motion conversion unit that is coupled to the second worm wheel part, converts a rotational motion of the second worm wheel part into a linear motion, and is able to press any one of the pair of brake pads. 
     Furthermore, the second worm wheel part may include a second worm wheel body that is engaged with the second worm shaft part, and the plurality of second gear teeth that are formed to be spaced apart from one another along an outer peripheral portion of the second worm wheel body, and are each provided with the second enveloping gear tooth portion and the second helical gear tooth portion. 
     Furthermore, the second enveloping gear tooth portion may be located on a side away from an axial force direction of the second worm wheel body on the second worm wheel body. 
     Furthermore, the first worm wheel part may include a plurality of first gear teeth engaged with the first worm shaft part, each including a first enveloping gear tooth portion having a first inclined portion that increases in height toward one end side from a center portion and a first helical gear tooth portion having a constant height from the center portion to another end side. 
     Furthermore, the first worm wheel part may include a first worm wheel body that has a center portion to which the first worm shaft part is coupled, and the plurality of first gear teeth that are formed to be spaced apart from one another along an outer peripheral portion of the first worm wheel body, and are each provided with the first enveloping gear tooth portion and the first helical gear tooth portion. 
     Furthermore, the first enveloping gear tooth portion may be located on a side away from an axial force direction of the first worm wheel body on the first worm wheel body. 
     Furthermore, the brake apparatus for a vehicle may further include a bearing part that is located inside the housing part, surrounds the second worm shaft part, and supports the rotation of the second worm shaft part. 
     According to a brake apparatus for a vehicle in accordance with the present disclosure, at least one of a plurality of worm wheels may include a plurality of gear teeth each including an enveloping gear tooth and a helical gear tooth and be in surface contact with a worm shaft during operation. Therefore, the rigidity of the worm wheel and the worm shaft may be improved because the worm wheel is able to withstand a heavy load, which makes it possible to substantially prevent the worm shaft from being damaged, and enables mass production through mold manufacturing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view illustrating a vehicle brake apparatus in accordance with an embodiment of the present disclosure. 
         FIG. 2  is a cross-sectional view taken along line A-A′ in  FIG. 1 . 
         FIG. 3  is an exploded perspective view of the vehicle brake apparatus in accordance with an embodiment of the present disclosure. 
         FIG. 4  is an enlarged view of an actuator device for a vehicle brake in accordance with an embodiment of the present disclosure. 
         FIG. 5  is a front view of  FIG. 4 . 
         FIG. 6  is an enlarged view of a second worm shaft part and a second worm wheel part of the actuator device for a vehicle brake in accordance with an embodiment of the present disclosure. 
         FIG. 7  is a cross-sectional view of main components of  FIG. 6 . 
         FIG. 8  is an enlarged view of a first worm shaft part and a first worm wheel part of the actuator device for a vehicle brake in accordance with an embodiment of the present disclosure. 
         FIG. 9  is a cross-sectional view of main components of  FIG. 8 . 
         FIG. 10  is a view illustrating an operation of the actuator device for the vehicle brake. 
     
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
     Hereinafter, an actuator device for a vehicle brake in accordance with an embodiment of the present disclosure will be described with reference to the accompanying drawings. 
     In this process, the thicknesses of lines or the sizes of elements illustrated in the drawings may be exaggerated for the purpose of clarity and convenience of explanation. Furthermore, terms to be described later are terms defined in consideration of functions thereof in the present disclosure and may be changed according to the intention of a user or an operator, or practice. Accordingly, such terms should be defined based on the disclosure over the present specification. 
       FIG. 1  is a view illustrating a vehicle brake apparatus in accordance with an embodiment of the present disclosure,  FIG. 2  is a cross-sectional view taken along line A-A′ in  FIG. 1 ,  FIG. 3  is an exploded perspective view of the vehicle brake apparatus in accordance with an embodiment of the present disclosure,  FIG. 4  is an enlarged view of an actuator device for a vehicle brake in accordance with an embodiment of the present disclosure,  FIG. 5  is a front view of  FIG. 4 ,  FIG. 6  is an enlarged view of a second worm shaft part and a second worm wheel part of the actuator device for a vehicle brake in accordance with an embodiment of the present disclosure,  FIG. 7  is a cross-sectional view of main components of  FIG. 6 ,  FIG. 8  is an enlarged view of a first worm shaft part and a first worm wheel part of the actuator device for a vehicle brake in accordance with an embodiment of the present disclosure,  FIG. 9  is a cross-sectional view of main components of  FIG. 8 , and  FIG. 10  is a view illustrating an operation of the actuator device for the vehicle brake. 
     Referring to  FIG. 1  to  FIG. 3 , a vehicle brake apparatus  1  in accordance with an embodiment of the present disclosure includes a caliper body  2 , brake pads  3 , a wheel disc  4 , and an actuator device  5  for a vehicle brake. 
     The brake pads  3  are provides as a pair and disposed to face each other on the caliper body  2 , and are disposed on two opposing sides of the wheel disc  4 , respectively. The actuator device  5  for a vehicle brake is installed on the caliper body  2  and is operated to press the brake pads  3  or to release the pressure to the brake pads  3 . At this time, when the brake pads  3  are pressed by the actuator device  5  for a vehicle brake, the brake pads  3  are moved toward the wheel disc  4  and are pressed against the wheel disc  4 , so that a braking force is generated. However, when the brake pads  3  is released from pressure by the actuator device  5  for a vehicle brake, the brake pads  3  are moved toward an opposite side of the wheel disc  4  and are not brought into contact with the wheel disc  4 , so that the braking force is released. 
     Referring to  FIG. 4  to  FIG. 10 , the actuator device  5  for a vehicle brake in accordance with an embodiment of the present disclosure includes a motor part  10 , a housing part  20 , a first worm shaft part  100 , a first worm wheel part  200 , a second worm shaft part  300 , a second worm wheel part  400 , and a linear motion conversion unit  500 . The first worm shaft part  100  is connected to the motor part  10  and is located inside the housing part  20 . The housing part  20  includes a housing body  21  and a housing cover  22 . The housing body  21  has one opened side, the motor part  10  is installed in the housing body  21 , and the first worm shaft part  100  is located inside the housing body  21 . The housing cover  22  is coupled to the housing body  21  to cover the one opened side. The first worm shaft part  100  is connected to a rotating shaft (not illustrated) of the motor part  10  and rotates by receiving power from the motor part  10 . 
     The first worm shaft part  100  includes a first worm shaft body  110  and a plurality of first worm shaft gear teeth  120 . The first worm shaft body  110  is connected to the rotating shaft of the motor part  10 . The plurality of first worm shaft gear teeth  120  are formed to be spaced apart from one another along the outer peripheral portion of the first worm shaft body  110  and are engaged with first gear teeth  220  of the first worm wheel part  200 . 
     The first worm wheel part  200  is located inside the housing part  20 , is engaged with the first worm shaft part  100 , and rotates with the rotation of the first worm shaft part  100 . The first worm wheel part  200  is located in the housing body  21  of the housing part  20 , rotates by receiving the rotational force of the first worm shaft part  100 , and rotates the second worm shaft part  300  to be described below. 
     The second worm shaft part  300  is located inside the housing part  20 , is connected to the first worm wheel part  200 , and rotates together with the first worm wheel part  200  when the first worm wheel part  200  rotates. The second worm shaft part  300  is coupled to a center portion of the first worm wheel part  200  and is located in the housing body  21  of the housing part  20 . 
     The second worm shaft part  300  includes a second worm shaft body  310  and a plurality of second worm shaft gear teeth  320 . The second worm shaft body  310  is coupled to the center portion of the first worm wheel part  200  and is located in the housing body  21  of the housing part  20 . The second worm shaft gear teeth  320  are formed to be spaced apart from one another along the outer peripheral portion of the second worm shaft body  310  and are engaged with a plurality of second gear teeth  420  of the second worm wheel part  400  to be described below. 
     The second worm wheel part  400  is engaged with the second worm shaft part  300  and includes the plurality of second gear teeth  420 . The second gear tooth  420  includes a second enveloping gear tooth portion  421  and a second helical gear tooth portion  422 . The second enveloping gear tooth portion  421  has a second inclined portion  421   a  that increases in height toward one end side from a center portion O. The second helical gear tooth portion  422  has a constant height from the center portion O to the other end side. 
     Specifically, the second worm wheel part  400  includes a second worm wheel body  410  and the plurality of second gear teeth  420 . The second worm wheel body  410  is engaged with the second worm shaft part  300 . 
     The plurality of second gear teeth  420  are formed to be spaced apart from one another along the outer peripheral portion of the second worm wheel body  410 , and are each provided with the second enveloping gear tooth portion  421  and the second helical gear tooth portion  422 . The second enveloping gear tooth portion  421  has the second inclined portion  421   a  that increases in height toward the one end side from the center portion O of the second worm wheel body  410 . The second enveloping gear tooth portion  421  is located on a side away from the axial force direction of the second worm wheel body  410  on the second worm wheel body  410 . The axial force direction is the same direction as a direction in which the linear motion conversion unit  500  to be described below is moved toward the brake pads  3  and is in close contact with the brake pads  3 . The second helical gear tooth portion  422  has a constant height from the center portion O of the second worm wheel body  410  to the other end side. 
     As shown in  FIG. 6  and  FIG. 7 , the second enveloping gear tooth portion  421  has the second inclined portion  421   a  that increases in height toward the right end in the drawing from a virtual reference line CL vertically passing through the center portion O of the second worm wheel body  410 . The second helical gear tooth portion  422  has a constant height from the virtual reference line CL vertically passing through the center portion O of the second worm wheel body  410  to the left end in the drawing. 
     In this way, the second gear tooth  420  of the second worm wheel part  400  includes the second enveloping gear tooth portion  421  and the second helical gear tooth portion  422 , and the second enveloping gear tooth portion  421  is located on the side away from the axial force direction of the second worm wheel body  410  and is in surface contact with the second worm shaft part  300 , which makes it possible to improve the rigidity of the second worm shaft part  300  and the second worm wheel part  400  to substantially prevent the second worm shaft part  300  and the second worm wheel part  400  from being damaged, and enables mass production through mold manufacturing. 
     The first worm wheel part  200  is engaged with the first worm shaft part  100  and includes the plurality of first gear teeth  220 . The first gear tooth  220  includes a first enveloping gear tooth portion  221  and a first helical gear tooth portion  222 . The first enveloping gear tooth portion  221  has a first inclined portion  221   a  that increases in height toward one end side from a center portion O′. The first helical gear tooth portion  222  has a constant height from the center portion O′ to the other end side. 
     Specifically, the first worm wheel part  200  includes a first worm wheel body  210  and the plurality of first gear teeth  220 . The first worm wheel body  210  has a center portion to which the first worm shaft part  100  is coupled. 
     The plurality of first gear teeth  220  are formed to be spaced apart from one another along the outer peripheral portion of the first worm wheel body  210 , and are each provided with the first enveloping gear tooth portion  221  and the first helical gear tooth portion  222 . The first enveloping gear tooth portion  221  has the first inclined portion  221   a  that increases in height toward the one end side from the center portion O′ of the first worm wheel body  210 . The first enveloping gear tooth portion  221  is located on a side away from the axial force direction of the first worm wheel body  210  on the first worm wheel body  210 . The axial force direction is the same direction as a direction in which the linear motion conversion unit  500  to be described below is moved toward the brake pads  3  and is in close contact with the brake pads  3 . The first helical gear tooth portion  222  has a constant height from the center portion O′ of the first worm wheel body  210  to the other end side. 
     As shown in  FIG. 8  and  FIG. 9 , the first enveloping gear tooth portion  221  has the first inclined portion  221   a  that increases in height toward the right end in the drawing from the virtual reference line CL vertically passing through the center portion O′ of the first worm wheel body  210 . The first helical gear tooth portion  222  has a constant height from the virtual reference line CL vertically passing through the center portion O′ of the first worm wheel body  210  to the left end in the drawing. 
     In this way, the first gear tooth  220  of the first worm wheel part  200  includes the first enveloping gear tooth portion  221  and the first helical gear tooth portion  222 , and the first enveloping gear tooth portion  221  is located on the side away from the axial force direction of the first worm wheel body  210  and is in surface contact with the first worm shaft part  100 , which makes it possible to improve the rigidity of the first worm shaft part  100  and the first worm wheel part  200  to substantially prevent the first worm shaft part  100  and the first worm wheel part  200  from being damaged, and enables mass production through mold manufacturing. 
     The linear motion conversion unit  500  is coupled to the second worm wheel part  400 , converts the rotational motion of the second worm wheel part  400  into a linear motion, and can press any one of the pair of brake pads  3 . 
     The linear motion conversion unit  500  is a device that converts the rotation of the second worm wheel part  400  into a linear motion, is moved toward the brake pads  3  along the rotation direction of the second worm wheel part  400  to press the brake pads  3 , or is moved to an opposite side of the brake pads  3  not to press the brake pads  3 . 
     The linear motion conversion unit  500  includes a screw bar part  510 , a spindle part  520 , and a piston part  530 . The screw bar part  510  is located inside the caliper body  2 , and rotates by receiving the rotational force of the second worm wheel part  400 . 
     The spindle part  520  is linearly moved by the rotation of the screw bar part  510 . The spindle part  520  is gear-connected to an outer side of the screw bar part  510 , and is linearly moved by the rotation of the screw bar part  510 . For example, the screw bar part  510  has a rod shape, is inserted into the spindle part  520 , and is provided on the outer side thereof with a male thread (not illustrated). The spindle part  520  is provided on the inner side thereof with a female thread (not illustrated) engaged with the male thread, and the rotation of the spindle part  520  is restricted by the screw bar part  510 . That is, the spindle part  520  may be moved in the left and right direction (see  FIG. 10 ) according to the rotation of the screw bar part  510 . 
     The piston part  530  is installed to surround the outer side of the spindle part  520 , and is moved together with the spindle part  520  to press the brake pads  3 . When the spindle part  520  presses the piston part  530 , the piston part  530  presses the brake pads  3  and the brake pads  3  is pressed against the wheel disc  4 , which makes it possible to generate a braking force. The piston part  530  in accordance with an embodiment is formed in a cylindrical shape, is opened in the direction in which the spindle part  520  is inserted, and has a shielded portion facing the brake pads  3 . 
     A bearing part  600  is located inside the housing part  20 , surrounds the second worm shaft part  300 , and supports the rotation of the second worm shaft part  300 . 
     It has been illustrated that, in the actuator device  5  for a vehicle brake in accordance with an embodiment of the present disclosure, a gear module unit including the first worm shaft part  100 , the first worm wheel part  200 , the second worm shaft part  300 , and the second worm wheel part  400  is configured in one stage, and each of the first worm wheel part  200  and the second worm wheel part  400  includes a plurality of gear teeth each including an enveloping gear tooth and a helical gear tooth; however, the present disclosure is not limited thereto and the gear module unit may be configured in two stages in different situations, and may be varied in design so that at least one of a plurality of worm wheels provided in the gear module unit includes a plurality of gear teeth each including an enveloping gear tooth and a helical gear tooth. 
     Although the present disclosure has been described with reference to the embodiments illustrated in the drawings, the embodiments of the disclosure are for illustrative purposes only, and those skilled in the art will appreciate that various modifications and other equivalent embodiments are possible from the embodiments. 
     Thus, the true technical scope of the present disclosure should be defined by the following claims.