Patent Publication Number: US-11391224-B2

Title: Compression-release type engine brake

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2019-0123906, filed on Oct. 7, 2019, the entire contents of which are incorporated herein by reference. 
     FIELD 
     The present disclosure relates to a compression-release engine brake. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
     In general, a brake system of an internal combustion engine vehicle uses a hydraulic pressure type of brake, but the engine brake is used to prevent premature abrasion of a brake pad during downhill driving or frequent sudden stops. 
     The compression-release engine brake device (namely, compression-release engine brake), which is a type of engine brake, temporarily opens an exhaust valve near a compress top dead center of a piston during the basic four strokes of the engine, i.e., exhausts compressed air in a cylinder out of the cylinder to thereby obtain a braking effect by inducing a pumping loss of an expansion stroke. 
     In a compression-release engine brake according to a conventional art, a socket module is applied between a valve bridge connected with a pair of exhaust valves, and an exhaust rocket arm. 
     In the socket module, the brake piston is provided inside the housing where the brake oil is introduced, and when the engine brake is operated, the brake piston moves downward to eliminate the gap between the exhaust rocker arm and the exhaust cam, thereby forcing the exhaust valve to be opened at the end of the compression stroke. 
     The exhaust valve is opened at the end of the compression stroke by the socket module to add braking force to the vehicle, but once the engine brake oil is introduced into the socket module, it is not exhausted, and thus the valve may be opened more by oil pressure formed in the socket module. 
       FIG. 12  is a graph that shows a valve lift displacement amount occurring in a conventional compression-release engine brake. 
     As shown in  FIG. 12 , there is a possibility of occurrence of a contact “A” between an exhaust valve and an engine piston. 
     In order to solve such a problem, the compression-release engine brake with a reset bracket is provided on one side of the socket module, and the reset bracket must be applied to the outside of the reset module as well, and thus there is a drawback in which the overall size increases. 
     In addition, the compress relaxation engine brake device according to the conventional art has a problem that the socket module rotates between the valve bridge and the exhaust rocker arm during continuous operation. 
     The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure, and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. 
     SUMMARY 
     An exemplary form of the present disclosure provides a compression-release engine brake that can automatically initialize a pressure inside a socket module by automatically exhausting the engine brake oil that has been introduced into the socket module during engine brake operation and prevents collision between exhaust valve and engine piston 
     In one or a plurality of exemplary forms of the present disclosure, the compression-release engine brake temporarily may open an exhaust valve at the end of the compression stroke, that is, near a top dead center of the piston, to exhaust compressed air in a cylinder to the outside the cylinder, thereby acquiring a braking effect by inducing a pumping loss in the expansion stroke. 
     In one form of the present disclosure, a compression-release engine brake for opening an exhaust valve at an end of a compression stroke of an engine may include: an exhaust rocker arm that rotates around a rocker arm shaft by a rotation of an exhaust cam that selectively contacts a roller mounted at one end of the exhaust rocker arm; a valve bridge that is disposed on the other end of the exhaust rocker arm, and is connected to a pair of exhaust valves, where the valve bridge includes a pair of rotation preventers protruded outward; a socket module that is disposed between the exhaust rocker arm and includes a housing configured to form a first space in which engine brake oil flows in through an inlet, a second space from which the engine brake oil is exhausted through an outlet; a reset valve partially inserted in the second space of the housing, and a reset guide module mounted on an upper part of a cylinder head, and selectively pushing the reset valve inside of the housing to exhaust the engine brake oil. 
     The pair of rotation preventers of the valve bridge may be protruded toward the outside from a central portion of the valve bridge, and formed to extend a certain length upward so that the part corresponding to the second space of the socket module is inserted. 
     The socket module further may include a brake piston moved in the up and down direction by the engine brake oil inserted into the first space, and contacting an upper surface of the valve bridge. 
     An upper and a lower protrusion may be formed on each exterior surface of the brake piston, and wherein, the compression-release engine brake may further include a stopper fitted to a side of the housing in correspondence between the upper protrusion and the lower protrusion. 
     The stopper may include a head portion and a body portion, and wherein, the body portion may be mounted to the housing, and an end of the head portion is protruded into the first space by a predetermined length to be positioned between the upper and lower protrusions. 
     The housing may further include a rounded mounting groove protruded upward from an upper center of the housing where an adjusting screw mounted to one end of the exhaust rocker arm is mounted. 
     Penetration holes in response to the second space may be formed in the housing on both sides in contact with the rotation preventer, and a part of the engine brake oil may be exhausted through the penetration hole. 
     The compression-release engine brake may further include a check valve provided in the first space to open and close the inlet. 
     The compression-release engine brake may further include a check spring provided on the upper portion of the brake piston to elastically support the check valve. 
     The reset valve may have a flow path groove that is concave inward from an upper exterior circumference of the reset valve, and wherein The compression-release engine brake may further include a reset spring elastically supports the reset valve. 
     An upper end of the oil passing groove may be caught on a slanted surface formed in the second space for preventing the reset valve from deviating downward. 
     The reset valve may open the outlet when the reset valve contacts with the guide rod. 
     The reset guide module may include a guide plate in which the pair of exhaust valves are fitted and seated on the upper part of the cylinder head, and a connection bracket is formed, and a guide rod mounted on the connecting bracket and selectively pushing the reset valve. 
     The compression-release engine brake according to an exemplary form of the present disclosure may automatically exhaust the brake oil introduced into socket module during engine brake operation by being provided with the reset guide module such that it is possible to prevent the exhaust valve from contacting the engine piston. 
     In addition, compression-release engine brake according to an exemplary form of the present disclosure may prevent wear of the socket module by exhausting a portion of the engine brake oil toward the reset guide module. 
     In addition, compression-release engine brake according to an exemplary form of the present disclosure may prevent rotation of the socket module during engine brake operation by applying a rotation preventer to one side of the valve bridge. 
     In addition, effects obtained or predicted by the exemplary forms of the present disclosure are disclosed directly or implicitly in a detailed description of an exemplary form of the present disclosure. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which: 
         FIG. 1  is a schematic diagram of a basic four-stroke cycle of an engine; 
         FIG. 2  is a schematic diagram of an engine cycle for description of a compression-release engine brake according to an exemplary form of the present disclosure; 
         FIG. 3  is a schematic diagram of the compression-release engine brake according to the exemplary form of the present disclosure; 
         FIG. 4  is a perspective view of a valve bridge applied to the compression-release engine brake in one form of the present disclosure; 
         FIG. 5  is a perspective view of the socket module applied to the compression-release engine brake in one form of the present disclosure; 
         FIG. 6  is a cross-sectional view of  FIG. 5 , taken along the line A-A; 
         FIG. 7  is a cross-sectional view of  FIG. 5 , taken along the line B-B; 
         FIG. 8  to  FIG. 11  sequentially illustrate an operation method of the compression release type engine brake according to another exemplary form of the present disclosure; and 
         FIG. 12  is a graph that shows a valve lift displacement amount occurring in use of a general compression-release engine brake. 
     
    
    
     The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
     As those skilled in the art would realize, the described forms may be modified in various different ways, all without departing from the spirit or scope of the present disclosure. 
     In the following description, dividing names of components into first, second, and the like is to divide the names because the names of the components are the same as each other, and an order thereof is not particularly limited. 
       FIG. 1  is a schematic diagram of a basic four-stroke cycle of an angle, and  FIG. 2  is a schematic diagram of an engine cycle for description of a compression-release engine brake according to an exemplary form of the present disclosure. 
     In general, the engine brake may be applied to prevent the vehicle from causing premature wear of the brake pads applied to the foot brake when driving downhill or when frequently stopping suddenly. 
     The compression-release engine brake is actuated in one of the four basic strokes of the engine, and opens an exhaust valve at the end of a compression stroke so that the engine can perform its braking function. 
     Referring to  FIG. 1 , a vehicle engine is driven by repeating a four-stroke cycle of intake, compression, combustion, and exhaust when driving. 
     As shown in  FIG. 2 , the compression-release engine brake temporarily opens an exhaust valve at the end of the compression stroke, that is, near a top dead center of the piston, to exhaust compressed air in a cylinder to the outside the cylinder, thereby acquiring a braking effect by inducing a pumping loss in the expansion stroke. 
     For this, the compression-release engine brake according to the exemplary form of the present disclosure may be formed as follows. 
       FIG. 3  is a schematic diagram of the compression-release engine brake according to an exemplary form of the present disclosure. 
     Referring to  FIG. 3 , in the compression release type engine brake, a rocker arm shaft  3  is inserted into an exhaust rocker arm  1  such that the exhaust rocker arm  1  rotates with respect to the rocker arm shaft  3 , a roller  5  is mounted to one end of the exhaust rocker arm  1 , and an adjusting screw  7  is mounted to the other end of the exhaust rocker arm  1 . 
     The roller  5  may contact or not contact an exhaust cam  20  installed on a camshaft. 
     The adjusting screw  7  is mounted to the other end of the exhaust valve  10  and is thus connected with a valve bridge  11  through a socket module  30  provided at a lower end thereof. 
     The valve bridge  11  is connected to the exhaust valve  10 , and the exhaust valve  10  may be provided as a pair. 
     In addition, the exhaust cam  20  may be divided into a brake cam lobe section and a main cam lobe section according to a profile, and the brake cam lobe section and the main cam lobe section may be implemented by forming a brake cam lobe  23  and a main cam lobe  25  on the exhaust cam shaft  21 . 
     The main cam lobe  25  may implement the exhaust stroke by contacting the roller  5 , and the brake cam lobe  23  may open the exhaust valve  10  by contacting the roller  5  when the engine brake is operated. 
     In addition, a bias spring (not shown) is mounted to the exhaust rocker arm  1 , and the bias spring lifts one end of the exhaust rocker arm  1 , which corresponds to the roller  5 , and the same time, provides an elastic force in a direction in which the other end of the exhaust rocker arm  1 , which corresponds to the adjusting screw  7 , to be closely attached to the valve bridge  11 . 
     Accordingly, in a state before the engine brake operation (in the basic engine stroke), the roller  5  maintains a distance with the brake cam lobe  23  of the exhaust cam  20 , and, in the exhaust stroke, the roller  5  is pushed upward only by the main cam lobe  25  of the exhaust cam  20 . 
     That is, when brake oil for operation of the engine brake is not supplied, a gap is formed between the roller  5  provided at the other end of the exhaust rocker arm  1  and the exhaust cam  20  and thus the brake cam lobe  23  of the exhaust cam  20  and the roller  5  do not contact each other, thereby causing the engine brake not to work. 
     On the other hand, when the engine brake oil is supplied to operate the engine brake, the socket module  30  lifts the other side of the exhaust rocker arm  1  up such that the roller  5  and the exhaust cam  20  are in constant contact, and thus, at the end of the compression stroke, the exhaust rocker arm  1  is operated by the brake cam lobe  23  of the exhaust cam  20 , so that the braking effect can be obtained. 
     The socket module  30  is applied between the exhaust rocker arm  1  and the valve bridge  11 . 
       FIG. 4  is a perspective view of a valve bridge applied to the compression-release engine brake in one exemplary form of the present disclosure. 
     Referring to  FIG. 4 , a rotation preventer  13  that prevents rotation of the socket module  30  may be formed on the valve bridge  11 , and the rotation preventer  13  may be formed in pairs. 
     The rotation preventer  13  is protruded toward the outside on the central portion of one side of the valve bridge  11 . 
     The rotation preventer  13  is formed in a pair and is formed along the up and down directions so that the portion corresponding to the second space  50  of the socket module  30 , which will be described below, is fitted and fixed. 
     That is, the socket module  30  can be inserted between the rotation preventers  13  of the valve bridge  11 . 
       FIG. 5  is a perspective view of the socket module applied to the compression-release engine brake according to the exemplary form of the present disclosure,  FIG. 6  is a cross-sectional view of  FIG. 5 , taken along the line A-A, and  FIG. 7  is a cross-sectional view of  FIG. 5 , taken along the line B-B. 
     Referring to  FIG. 5  to  FIG. 7 , the socket module  30  applied to the compression-release engine brake includes a housing  40 , a brake piston  70 , and a reset valve  100 . 
     In one form, the housing  40  forms a first space  45  in which the engine brake oil flows in through an inlet  43 , and a second space  50  from which the engine brake is exhaust through an outlet  47 . 
     The housing  40  includes a mounting portion  41  that protrudes upward from a center of an upper center thereof. The mounting portion  41  includes a rounded mounting groove provided therein such that the adjusting screw  7  is mounted thereto. 
     That is, the adjusting screw  7  is configured to be seated on the mounting portion  41  and not detached from the mounting portion  41 . 
     Also, the mounting portion  41  communicates with the first space  45  through the inlet  43 . 
     The inlet  43  is configured to be opened and closed by a check valve  80 . 
     The check valve  80  is elastically supported by a check spring  81  disposed inside a receiving groove  71  formed in the center of the upper surface of the brake piston  70 . 
     The first space  45  communicates with the second space  50  through a first outlet  47   a.    
     In the second space  50 , the first outlet  47   a  connected to the first space  45 , a second outlet  47   b  lower and parallel to the first outlet  47   a , and penetration holes  49  lower vertical direction with the first outlet  47   a  are formed. 
     Penetration holes  49  are formed on both side surfaces of the housing  40  corresponding to the second space  50 . The rotation preventers  13  contact the side surfaces, and a part of the engine brake oil is leaked through the penetration holes  49  for lubrication. 
     The top of the second space  50  can be closed by a cap  60 . 
     The brake piston  70  is inserted into the first space  45  of the housing  40  to make contact with the upper surface of the valve bridge  11 . 
     The brake piston  70  is provided to be movable up and down in the first space  45  by the engine brake oil flowing into the housing  40 . 
     An upper protrusion  73  and a lower protrusion  75  are formed on each exterior surface of the brake piston  70 . 
     Positions of the brake piston  70  is limited by a stopper  90  fitted to the housing  40  in correspondence between the upper protrusion  73  and the lower protrusion  75 . 
     The stopper  90  includes a head portion  91  and a body portion  93 . 
     When the stopper  90  is mounted, an end of the body portion  93  is inserted through the housing and then positioned between the upper and lower protrusions  73  and  75 . Since the end of the stopper  90  is positioned between the upper protrusion  73  and the lower protrusion  75  of the brake piston  70 , the stopper  90  is configured to limit the position of the brake piston  70 . 
     The stopper  90  can adjust the insert length of the body portion  93  in the form of a screw. 
     A reset valve  100  is inserted into the second space  50  of the housing  40 . 
     In the reset valve  100 , an oil passing groove  110  is formed in an exterior circumference on the upper side inserted into the second space  50 . 
     In the reset valve  100 , a stepped surface is formed at the upper end by the oil passing groove  110 , which is hung on a slanted surface  51  formed by the first outlet  47   a  and the second outlet  47   b  in the second space  50  so that the reset valve  100  is connected to the housing  40 . That is, the reset valve  100  is caught in the second space  50  for preventing the reset valve  100  from deviating downward. 
     And the reset valve  100  is elastically supported by a reset spring  120 . 
     The reset spring  120  is supported on a lower side by a spring pin  121  fixed to the reset valve  100 . 
     The reset valve  100  performs an upward operation to open the outlet  47 , and then returns to close the outlet  47  by the restoring force of the reset spring  120 . 
     A reset guide module  130  is configured on the lower side corresponding to the reset valve  100  described above. 
     Referring to  FIG. 3 , the reset guide module  130  includes a guide plate  131  and a guide rod  137 . 
     In the guide plate  131 , mount holes  135  are formed so that the a pair of exhaust valves  10  are inserted on both sides of the length direction, and a connecting bracket  133  is formed in the center of the upper surface. 
     The guide plate  131  fits on a pair of exhaust valve  10  through the mount hole  135  and rests on the cylinder head  9 . 
     The guide rod  137  is mounted on the connecting bracket  133 . The guide rod  137  may be a hollow shape, and a part of the reset valve  100  can be inserted therein. 
     When the socket module  30  descends and the exhaust valve  10  is opened, the guide rod  137  pushes the reset valve  100  and the reset spring  120  is compressed, so that the reset valve  100  rises and the outlet  47  opens. 
     At this time, as the outlet  47  is opened, the engine brake oil inflowed into the housing  40  is exhausted, and the pressure inside the housing  40  can be returned to an initial state. 
     When the reset valve  100  is inserted into the guide rod  137 , part of the engine brake oil exhausted from the penetration hole  49  passes through the rotation preventer  13  and flows in between the reset valve  100  and the guide rod  137 . 
     The compression-release engine brake configured as described above is operated as follows. 
       FIG. 8  to  FIG. 11  sequentially illustrate an operation method of the compression release type engine brake according to the exemplary form of the present disclosure. 
     Referring to  FIG. 8 , when the engine brake is operated, the brake oil flows through a flow path inside the adjusting screw  7  to the inlet  43  of the housing  40 . 
     Then, the check valve  80  that opens and closes the inlet  43  descends to open the inlet  43  and then the engine brake oil is inflow into the first space  45  of the housing  40 . 
     Referring to  FIGS. 9A and 9B , when brake oil is introduced into the first space  45 , the brake piston  70  descends by the hydraulic pressure and, at the same time, the check valve  80  closes the inlet  43  by an elastic force of the check spring  81  such that the first space  45  is closed and sealed. 
     As the brake piston  70  descends, the overall length of the up and down direction of the socket module  30  becomes longer, and thus, the end corresponding to the socket module  30  of the exhaust rocker arm  1  is pushed upwards to rotate the exhaust rocker arm  1  with respect to the rocker arm shaft  3 . 
     Subsequently, the roller  5  of the exhaust rocker arm  1  and the exhaust cam  20  make contact. 
     When the exhaust cam  20  rotates and thus the brake cam lobe  23  of the exhaust cam  20  and the roller  5  contact each other, an end portion of the exhaust rocker arm  1 , corresponding to the roller  5 , is lifted upward and rotates with reference to the rocker arm shaft  3  by the protruded brake cam lobe  23 . 
     Due to such an operation, the valve bridge  11  is pressed downward and the exhaust valve  10  is opened. At the end of the compress stroke, that is, the exhaust valve  10  is temporarily opened near the top dead center to exhaust the compressed air in the cylinder out of the cylinder, thereby inducing a pumping loss of the expansion stroke to obtain a braking effect. 
     Referring to  FIG. 10 , as the exhaust rocker arm  1  rotates, the guide rod  137  pushes the reset valve  100  and the reset valve  100  moves relative to the upward. 
     Accordingly, the first outlet  47   a  and the second outlet  47   b  are opened through the oil passing groove  110  of the reset valve  100 . 
     The engine brake oil inflow to the first space  45  is exhausted through the opened first outlet  47   a  and second outlet  47   b.    
     Referring to  FIG. 11 , when the engine brake oil is completely exhausted inside the housing  40 , the brake piston  70  moves upward and returns to its original position, and the reset valve  100  is also automatically returned to its initial state, a certain gap between the roller  5  and exhaust cam  20  may be maintained. 
     Accordingly, the compression-release engine brake according to an exemplary form of the present disclosure may automatically initialize the internal pressure of the socket module  30  by exhausting the engine brake oil supplied inside the socket module  30  after opening the exhaust valve  10 . 
     So that it is possible to prevent the exhaust valve  10  from contacting the engine piston. 
     Further, the reset valve  100  is inserted inside the guide rod  137 , and the penetration holes  49  are formed in the housing  40  to allow the engine brake oil through the penetration holes  49  to be supplied between the reset valve  100  and guide rod  137 . 
     In addition, the compression-release engine brake according to an exemplary form of the present disclosure can prevent rotation of the socket module  30  during engine brake operation by applying rotation preventer  13  to one side of the valve bridge  11 . 
     The engine brake oil exhausted through the penetration holes  49  of the housing  40  can also act as a lubricant between the housing  40  and rotation preventer  13 . 
     While this present disclosure has been described in connection with what is presently considered to be practical exemplary forms, it is to be understood that the present disclosure is not limited to the disclosed forms. On the contrary, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. 
     
       
         
           
               
             
               
                   
               
               
                 &lt;Description of symbols&gt; 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 1: exhaust rocker arm 
                 3: rocker arm shaft 
               
               
                   
                 5: roller 
                 7: adjusting screw 
               
               
                   
                 9: cylinder head 
                 10: exhaust valve 
               
               
                   
                 11: valve bridge 
                 13: rotation preventer 
               
               
                   
                 20: exhaust cam 
                 21: exhaust camshaft 
               
               
                   
                 23: brake cam lobe 
                 25: main cam lobe 
               
               
                   
                 30: socket module 
                 40: housing 
               
               
                   
                 41: mounting portion 
                 43: inlet 
               
               
                   
                 45: first space 
                 47: outlet 
               
               
                   
                 49: penetration hole 
                 50: second space 
               
               
                   
                 51: slanted surface 
                 60: cap 
               
               
                   
                 70: brake piston 
                 71: receiving groove 
               
               
                   
                 73: upper protrusion 
                 75: lower protrusion 
               
               
                   
                 80: check valve 
                 81: check spring 
               
               
                   
                 90: stopper 
                 91: head portion 
               
               
                   
                 93: body portion 
                 100: reset valve 
               
               
                   
                 110: oil passing groove 
                 120: reset spring 
               
               
                   
                 121: spring pin 
                 130: reset guide module 
               
               
                   
                 131: guide plate 
                 133: connecting bracket 
               
               
                   
                 135: mount hole 
                 137: guide rod