Patent Publication Number: US-2016245348-A1

Title: Dih type parking brake apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to Korean Patent Application No. 10-2015-0026423, filed Feb. 25, 2015, the entire contents of which is incorporated herein for all purposes by this reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Various embodiments of the present invention relate to a parking brake apparatus of a vehicle; and, particularly, to a drum-in-hat (DIH) type parking brake apparatus capable of reducing a torque deviation at a shoe during braking. 
     2. Description of Related Art 
     A DIH type parking brake  100  as one of parking brakes of vehicles, as illustrated in  FIG. 1 , includes a dust cover  111  and a torque plate  112  which are mounted to a knuckle (or a carrier) portion of a wheel and are connected with a parking cable or a hydraulic line. In addition, the DIH type parking brake  100  includes a pair of brake shoes  114 , each having a semicircular shape and a lining  114   a,  or one brake shoe  114  which has a ring shape opened at a portion thereof and a lining  114   a.  When actuation force is input to the brake from the parking cable or the hydraulic line, the brake shoe(s)  114  is/are spread outward so as to exhibit braking force. 
       FIG. 1  is a perspective view illustrating a DIH type parking brake apparatus  100  equipped with one brake shoe  114 . When an oil pressure is provided to a piston  113 , the brake shoe  114  is spread while rods  115  installed to both ends of the piston  113  extend, thereby allowing braking force to be exhibited. The rods  115  installed to both left and right sides of the piston  113  have catching portions  115   b  formed to prevent end portions of the brake shoe  114  from being detached only in the left and right directions. 
     The above DIH type parking brake apparatus according to the related art is not provided with a means for preventing one-sided contact of the brake shoe  114 . That is, a rotational moment is applied to the brake shoe  114  during braking, so that one-sided contact is generated at any end portion of the brake shoe  114  while the end portion of the brake shoe  114  drops or rises, resulting in generation of uneven wear and torque concentration. 
     For example, when a counterclockwise rotational moment is applied to the brake shoe  114 , one-sided contact is generated while the end portion of the brake shoe  114  coming into contact with the left end of the piston  113  drops and the end portion of the brake shoe  114  coming into contact with the right end of the piston  113  rises, as illustrated in  FIG. 1  and  FIG. 2 . 
     Due to such one-sided contact, uneven wear is generated in the lining  114   a  coming into contact with the brake shoe  114  at a portion of the brake shoe  114  located behind the piston  113  in a rotation direction (that is, a portion located to the right of the piston), and a phenomenon in which torque is concentrated on a portion of the brake shoe  114  is generated as indicated by a torque diagram in  FIG. 2 . Due to the torque deviation as described above, a braking force deviation is generated at the left and right end portions of the brake shoe  114 , thereby causing the brake apparatus to fail to pass certification of various regulations. 
     However, since the DIH type parking brake apparatus according to the related art is not provided with a means for preventing drop or rise of the end portions of the brake shoe  114 , the above-mentioned phenomenon is consistently generated. That is, the rods  115  coming into contact with the end portions of the brake shoe  114  have the catching portions  115   b  formed to prevent the end portions of the brake shoe  114  from being detached only in the left and right directions, but is not provided with a means for preventing vertical movement of the end portions of the brake shoe  114  in the rods  115 . 
     The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art. 
     BRIEF SUMMARY 
     Various aspects of the present invention are directed to providing a DIH type parking brake apparatus capable of reducing one-sided contact of a brake shoe by preventing drop or rise of end portions of the brake shoe during braking. 
     Various aspects of the present invention are directed to providing a DIH type parking brake apparatus capable of preventing a phenomenon in which torque is concentrated on a portion of a brake shoe by preventing drop or rise of end portions of the brake shoe during braking. 
     According to various aspects of the present invention, a drum-in-hat (DIH) type parking brake apparatus including a drum which is integrally coupled to and is rotated along with an axle of a vehicle, a brake shoe installed to a vehicle body so as to come into contact with the drum, and an actuation device for spreading the brake shoe such that the brake shoe comes into contact with the drum may include rods slidably disposed on the actuation device so as to press end portions of the brake shoe while extending from the actuation device during braking, and movement restriction devices vertically formed on front surfaces of the rods so as to prevent the end portions of the brake shoe from dropping or rising when the vehicle is braked. 
     One of the movement restriction devices may be a drop prevention stopper formed at a lower portion of the front surface of the associated rod to prevent the associated end portion of the brake shoe from dropping. 
     The drop prevention stopper may be formed at the rod coming into contact with the end portion of the brake shoe located in front of a piston as the actuation device in a rotation direction of a wheel during the braking. 
     The drop prevention stopper may have an inclined surface formed to be inclined relative to a surface perpendicular to a sliding direction of the rod so as to support a lower end of the end portion of the brake shoe. 
     The drop prevention stopper may be formed at an inclination angle of 18° to 22° to the surface perpendicular to the sliding direction of the rod. 
     One of the movement restriction devices may be a rise prevention stopper formed at an upper portion of the front surface of the associated rod to prevent the associated end portion of the brake shoe from rising. 
     The rise prevention stopper may be formed at the rod coming into contact with the end portion of the brake shoe located behind a piston as the actuation device in a rotation direction of a wheel during the braking. 
     The rise prevention stopper may have an inclined surface formed to be inclined relative to a surface perpendicular to a sliding direction of the rod so as to support an upper end of the end portion of the brake shoe. 
     The rise prevention stopper may be formed at an inclination angle of 18° to 22° to the surface perpendicular to the sliding direction of the rod. 
     It is understood that the term “vehicle” or “vehicular” or other similar terms as used herein is inclusive of motor vehicles in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g., fuel derived from resources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle that has two or more sources of power, for example, both gasoline-powered and electric-powered vehicles. 
     The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description, which together serve to explain certain principles of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view illustrating a drum-in-hat (DIH) type parking brake apparatus according to the related art. 
         FIG. 2  is a front view illustrating the DIH type parking brake apparatus according to the related art. 
         FIG. 3  is an enlarged perspective view illustrating an installation portion of a piston in the DIH type parking brake apparatus according to the related art. 
         FIG. 4  is a perspective view illustrating one rod installed between a brake shoe and the piston in the DIH type parking brake apparatus according to the related art. 
         FIG. 5  is an enlarged perspective view illustrating an installation portion of a piston in an exemplary DIH type parking brake apparatus according to the present invention. 
         FIG. 6  is a front view illustrating the DIH type parking brake apparatus according to the present invention. 
         FIG. 7  and  FIG. 8  are cross-sectional views illustrating respective rods between a brake shoe and the piston in the exemplary DIH type parking brake apparatus according to the present invention. 
     
    
    
     It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment. 
     DETAILED DESCRIPTION 
     Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that the present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims. 
     A drum-in-hat (DIH) type parking brake apparatus according to various embodiments of the present invention includes a drum which is integrally coupled to and is rotated along with an axle of a vehicle, a brake shoe  14  installed to a vehicle body so as to come into contact with the drum, and an actuation device for spreading the brake shoe  14  such that the brake shoe  14  comes into contact with the drum. The DIH type parking brake apparatus includes rods which are slidably installed to the actuation device and press end portions of the brake shoe  14  while extending from the actuation device during braking, and movement restriction devices which are vertically formed on front surfaces of the rods  15  and  16  so as to prevent drop or rise of the end portions of the brake shoe  14  when the vehicle is braked. 
     The DIH type parking brake apparatus  1  includes the drum (not shown) rotated along with the axle and the brake shoe  14  fixedly installed to the vehicle body. The brake shoe  14  is spread such that the brake shoe  14  comes into close contact with the drum and then a lining  14   a  installed on an outside surface of the brake shoe  14  comes into contact with an inside surface of the drum, thereby allowing braking force to be exhibited. 
     The brake shoe  14  has a ring shape and a partial section of the brake shoe  14  may be removed such that the actuation device for spreading the brake shoe  14  is located at the partial section. The brake shoe  14  may be formed integrally with a torque plate  12  coupled to a dust cover  11  of the DIH type parking brake apparatus  1 . 
     The actuation device for spreading the brake shoe  14  may be a piston  13  for spreading the brake shoe  14  while extending by an oil pressure. 
     The rods  15  and  16  are fitted to both ends of the piston  13  and slide outward when the pressurized oil pressure acts on the piston  13 , so that the rods  15  and  16  come into contact with the respective end portions of the brake shoe  14 . 
     In the present invention, when the pressurized oil is supplied to the piston  13 , the movement restriction devices for preventing movement of the brake shoe  14 , namely, for preventing drop or rise of the end portions of the brake shoe  14  are respectively formed at the rods  15  and  16  which slide and protrude from the piston  13 . 
     The stationary brake shoe  14  comes into contact with the rotating drum and the brake shoe  14  rotates in a rotation direction of a wheel, during braking. In this case, the respective end portions of the brake shoe  14  coming into contact with the rods  15  and  16  drop or rise. 
     That is, the end portion of the brake shoe  14  located in front of the piston  13  in the rotation direction of the wheel (the end portion of the brake shoe  14  located at the left in  FIG. 6 ) drops, whereas the other end portion (the end portion located at the right in  FIG. 6 ) rises. 
     In order to prevent this, the movement restriction devices for preventing drop or rise of the end portions of the brake shoe  14  are installed to the rods  15  and  16 . 
     When the end portions of the brake shoe  14  drop or rise, the movement restriction devices may prevent the end portions of the brake shoe  14  from dropping or rising by forming lower or upper portions of the front surfaces of the rods  15  and  16  coming into contact with the end portions of the brake shoe  14  at higher locations than portions coming into contact with the end portions of the brake shoe  14 . 
     For example, the movement restriction devices may be a drop prevention stopper  15   c  or a rise prevention stopper  16   c.    
     First, the drop prevention stopper  15   c  will be described below. 
     The drop prevention stopper  15   c  is formed to protrude from the front surface of the rod  15  so as to prevent the associated end portion of the brake shoe  14  from dropping. As illustrated in detail in  FIG. 5  and  FIG. 7 , the rod  15  has a seating surface  15   a  which is formed on the front surface thereof to come into contact with the end portion of the brake shoe  14 , and a catching portion  15   b  which is formed to prevent the end portion of the brake shoe  14  from being detached from the seating surface  15   a  in a left and right direction of the seating surface  15   a  (in a width direction of the vehicle). In this case, the drop prevention stopper  15   c  protrudes from a lower portion of the seating surface  15   a  so as to fill a gap between the lower portion of the seating surface  15   a  and the catching portion  15   b.  The drop prevention stopper  15   c  has an inclined surface  15   d  formed at a certain angle to the seating surface, and the inclined surface  15   d  may have an inclination angle α of about 20°, for example, an inclination angle α of 18° to 22°. 
     As illustrated in  FIG. 6 , the drop prevention stopper  15   c  supports a lower end of the end portion of the brake shoe  14 , thereby allowing the end portion of the brake shoe  14  to be prevented from dropping. 
     Thus, the drop prevention stopper  15   c  is formed at the rod  15  coming into contact with the dropping end portion of the end portions of the brake shoe  14  during braking, namely, is formed at the rod  15  coming into contact with the brake shoe  14  located in front of the piston  13  in the rotation direction. 
     The rise prevention stopper  16   c  is formed at the rod  16  located opposite to the rod  15  formed with the drop prevention stopper  15   c,  from among the two rods  15  and  16  installed to the piston  13 . 
     The rise prevention stopper  16   c  is formed at the rod  16  coming into contact with the rising end portion of the end portions of the brake shoe  14  during braking, namely, is formed at the rod  16  coming into contact with the brake shoe  14  located behind the piston  13  in the rotation direction. 
     The rise prevention stopper  16   c  may be formed in a manner similar to the drop prevention stopper  15   c.  However, the portion at which the rise prevention stopper  16   c  is formed differs from that of the rise prevention stopper  16   c  since the rise prevention stopper  16   c  prevents the end portion of the brake shoe  14  from rising. 
     That is, the rod  16  has a seating surface  16   a  formed on the front surface thereof to seat the end portion of the brake shoe  14  and a catching portion  16   b  formed in a left and right direction of the seating surface  16   a,  and the rise prevention stopper  16   c  protrudes from a upper portion of the seating surface  16   a  so as to fill a gap between the upper portion of the seating surface  16   a  and the catching portion  16   b.    
     The rise prevention stopper  16   c  also has an inclined surface formed at a certain inclination angle α to the seating surface  16   a.  The inclination angle α may be an angle of about 20°, for example, an angle of 18° to 22°. The inclination angle formed by the inclined surface  16   d  of the rise prevention stopper  16   c  may be similar to or differ from the inclination angle formed by the inclined surface  15   d  of the drop prevention stopper  15   c.    
     An operation of the DIH type parking brake apparatus having the above-mentioned configuration according to various embodiments of the present invention will be described below. 
     When the vehicle is braked, a rotational moment is applied to the brake shoe  14  in the rotation direction of the wheel of the vehicle and thus the end portions of the brake shoe  14  drop or rise by the rotational moment. 
     For example, when a counterclockwise rotational moment is applied to the brake shoe  14 , dropping force acts on the end portion of the brake shoe  14  located in front of the piston  13  (at the left in  FIG. 6 ) in the rotation direction and rising force acts on the end portion of the brake shoe  14  located behind the piston  13  (at the right in  FIG. 6 ) in the rotation direction. 
     However, as shown in  FIG. 6 , since the end portions of the brake shoe  14  are caught by the drop prevention stopper  15   c  and the rise prevention stopper  16   c  formed at the respective rods  15  and  16 , the end portions of the brake shoe  14  are prevented from dropping or rising to be maintained at the initial positions. 
     As described above, since the brake shoe  14  is maintained at the initial position even though the vehicle is braked, the brake shoe  14  relatively uniformly comes into contact with the drum. Through such a configuration, since the present invention has a torque distribution such as the torque diagram illustrated in  FIG. 6 , a torque deviation is reduced compared to the related art. 
     In addition, since the torque deviation is reduced at the brake shoe  14  and the braking force is uniformly exhibited in the brake shoe  14 , the DIH type parking brake apparatus may pass various types of certification and prevent uneven wear of the brake shoe  14 . 
     In accordance with various embodiments of the present invention, a DIH type parking brake apparatus can prevent one-sided contact of a brake shoe by preventing drop or rise of end portions of the brake shoe from rods extending from a piston during braking such that the brake shoe is maintained at an initial installation position. 
     In addition, since the one-sided contact of the brake shoe is prevented, a phenomenon in which torque is concentrated on a portion of the brake shoe can be reduced and thus a deviation between braking forces generated at left and right end portions of the brake shoe can be reduced. 
     In addition, since the one-sided contact of the brake shoe is reduced, it is possible to prevent uneven wear due to the one-sided contact. 
     For convenience in explanation and accurate definition in the appended claims, the terms “upper” or “lower”, “inner” or “outer” and etc. are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures. 
     The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. 
     The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.