Abstract:
Disclosed herein is a pulsation damping device of a hydraulic brake system. The pulsation damping device of a hydraulic brake system which attenuates a pressure pulsation of brake oil discharged from a pump comprise a sleeve inserted into a bore which communicates with an inport into which the brake oil is introduced and an outport through which the brake oil is discharged, wherein one end of the sleeve is open and the other end is closed, a damping member accommodated in the sleeve and hollowed to form a damping space therein, and a stopper member configured to block one open end of the bore and coupled to an opening of the sleeve.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of Korean Patent Application No. 2015-0124029, filed on Sep. 2, 2015 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    Embodiments of the present disclosure relate to a hydraulic brake system, and more particularly, to a pulsation damping device of a hydraulic brake system which attenuates a pressure pulsation of brake oil discharged from a pump. 
         [0004]    2. Description of the Related Art 
         [0005]    In general, in order to control brake hydraulic pressure to be transferred to a brake of a vehicle, a hydraulic brake system includes a modulator block, in which a plurality of solenoid valves, a low pressure accumulator in which oil is temporarily stored, a pump disposed to be connected to an outlet of the low pressure accumulator for pumping the oil stored in the low pressure accumulator, and a motor for driving the pump are installed, and an electronic control unit (ECU) for controlling components by which the modulator block is electrically operated. 
         [0006]    Such a hydraulic brake system adopts and uses various structures including a pulsation damping device having a predetermined damping space for attenuating a pressure pulsation which is generated because hydraulic pressure of brake oil discharged from a pump is at high pressure, an orifice portion at an outport through which brake oil is discharged via the pulsation damping device, etc. For example, a generally known pulsation damping device is formed to attenuate a pressure pulsation generated according to pressure discharged from a pump by having a damping space, a spring provided in the damping space, a piston elastically supported by the spring, a sealing member for shielding the damping space from the outside, etc. 
         [0007]    However, since a structure for installation of the above-described pulsation damping device is complex, there are problems in that a manufacturing process is difficult and cost is also increased. Further, since a structure in which the pressure pulsation is attenuated using the spring is formed, there is a problem in that a pressure pulsation attenuation function is not smoothly performed because durability of the spring or the like is degraded when the spring is used for a long time. 
       SUMMARY 
       [0008]    Therefore, it is an aspect of the present disclosure to provide a pulsation damping device of a hydraulic brake system having a simple structure to be easily installed and capable of efficiently attenuating a pressure pulsation. 
         [0009]    Additional aspects of the disclosure will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the disclosure. 
         [0010]    In accordance with one aspect of the present disclosure, a pulsation damping device of a hydraulic brake system which attenuates a pressure pulsation of brake oil discharged from a pump, the device comprising: a sleeve inserted into a bore which communicates with an inport into which the brake oil is introduced and an outport through which the brake oil is discharged, wherein one end of the sleeve is open and the other end is closed; a damping member accommodated in the sleeve and hollowed to form a damping space therein; and a stopper member configured to block one open end of the bore and coupled to an opening of the sleeve. 
         [0011]    The sleeve includes a shoulder portion which extends from the opening, and the stopper member includes a step corresponding to the shoulder portion. 
         [0012]    A concave-convex portion is formed on an outer circumferential surface of the damping member in a longitudinal direction; and an auxiliary damping space is formed between the sleeve and the concave-convex portion. 
         [0013]    The stopper member includes a first coupling portion which is coupled to the damping member for sealing the damping space and a second coupling portion which is coupled to the sleeve for sealing between the damping space and the auxiliary damping space. 
         [0014]    The damping member is positioned under the second coupling portion. 
         [0015]    The stopper member includes: an insertion portion inserted into and coupled to a hollow portion of the damping member; and a cap portion integrally formed with the insertion portion and configured to block the one open end of the bore. 
         [0016]    At least one first coupling groove or first coupling protrusion is formed in an outer circumferential surface of the insertion portion; and a coupling protrusion which fits the first coupling groove or a coupling groove which couples with the first coupling protrusion is formed on inner circumferential surface of the damping member into which the insertion portion is inserted. 
         [0017]    The stopper member includes a second coupling groove provided in an outer surface thereof to be coupled with the sleeve; and the sleeve includes a hook portion which enters the second coupling groove and is deformed to be caught at the second coupling groove. 
         [0018]    The damping member is formed of a rubber material to be elastically deformed. 
         [0019]    A flow path by which the inport and the outport are in communication with the damping space is formed in the stopper member. 
         [0020]    A space through which the brake oil is introduced and discharged is formed between the stopper member and the bore in a region in which the flow path passing through the stopper member is formed. 
         [0021]    The bore includes a lower bore in which a lower portion of the sleeve is accommodated and an upper bore in which the shoulder portion of the sleeve is accommodated; inner diameter of the lower bore is provided to be smaller than inner diameter of the upper bore; and a space through which the brake oil is introduced and discharged is formed between the sleeve and the upper bore in a region in which the inport and the outport are provided. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    These and/or other aspects of the disclosure will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
           [0023]      FIG. 1  is a hydraulic circuit diagram schematically illustrating a hydraulic brake system provided with a pulsation damping device according to an exemplary embodiment of the present disclosure. 
           [0024]      FIG. 2  is a perspective view of an assembly illustrating a state in which a pulsation damping device provided in a hydraulic brake system according to an exemplary embodiment of the present disclosure is being assembled in a modulator block. 
           [0025]      FIG. 3  is a perspective view of the assembly shown in  FIG. 2 . 
           [0026]      FIG. 4  is a cross-sectional view illustrating a flow of brake oil whose pressure pulsation is attenuated by the pulsation damping device of the hydraulic brake system. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    Hereinafter, embodiments of the present disclosure will be described in detail with reference to accompanying drawings. The accompanying drawings are examples which provide the concept of the present disclosure to those skilled in the art. The present disclosure is not limited to the accompanying embodiments and may be implemented in different forms. Parts irrelevant to description are omitted in the drawings in order to clearly describe the present disclosure, and widths, lengths, and thicknesses of components in the drawings may be exaggerated for convenience of description. 
         [0028]      FIG. 1  is a hydraulic circuit diagram schematically illustrating a hydraulic brake system provided with a pulsation damping device according to an exemplary embodiment of the present disclosure. 
         [0029]    Referring to  FIG. 1 , the hydraulic brake system includes a brake pedal  10  to which an operating force of a driver is applied, a brake booster  11  which increases pedal effort due to the pedal effort of the brake pedal  10 , using a pressure difference between vacuum pressure and atmospheric pressure, a master cylinder  20  which generates pressure using the brake booster  11 , a first hydraulic circuit  40 A which connects a first port  21  of the master cylinder  20  and wheel cylinders  30  provided on two wheels FR and RL and controls hydraulic pressure transmission, and a second hydraulic circuit  40 B which connects a second port  22  of the master cylinder  20  and wheel cylinders  30  provided on the two remaining wheels FL and RR and controls hydraulic pressure transmission. The first hydraulic circuit  40 A and the second hydraulic circuit  40 B are compactly installed in a modulator block  40 . 
         [0030]    Each of the first hydraulic circuit  40 A and the second hydraulic circuit  40 B includes solenoid valves  41  and  42  for controlling brake hydraulic pressure transferred to two pairs of wheel cylinders  30 , a pump  44  for suctioning and pumping brake oil discharged from wheel cylinders  30  or brake oil discharged from the master cylinder  20  by driving a motor  45 , a low pressure accumulator  43  for temporarily storing the brake oil discharged from the wheel cylinders  30 , a main flow path  47   a  which connects an outlet of the pump  44  to the master cylinder  20 , an auxiliary flow path  48   a  which guides the brake oil from the master cylinder  20  to an inlet of the pump  44  to be suctioned, and an electronic control unit (ECU) (not shown) which controls driving of the plurality of solenoid valves  41  and  42  and the motor  45 . 
         [0031]    Here, as shown in the drawing, the solenoid valves  41  and  42 , the low pressure accumulator  43 , the pump  44 , the main flow path  47   a , and the auxiliary flow path  48   a  are provided in each of the first and second hydraulic circuits  40 A and  40 B. 
         [0032]    More specifically, the plurality of solenoid valves  41  and  42  are related to upstream side and downstream side of each of the wheel cylinders  30  and are classified as a normal open type solenoid valve  41 , which is disposed at the upstream side of each wheel cylinder  30  and usually maintains an open state, and a normal closed type solenoid valve  42  which is disposed at the downstream side of each wheel cylinder  30  and usually maintains a closed state. Opening and closing operations of the solenoid valves  41  and  42  are controlled by the ECU, and the normal closed type solenoid valve  42  is opened by decompression braking so that brake oil discharged from the wheel cylinder  30  is temporarily stored in the low pressure accumulator  43 . 
         [0033]    The pump  44  is driven by the motor  45  and suctions and discharges the brake oil stored in the low pressure accumulator  43 , and hydraulic pressure is thus transferred to the wheel cylinder  30  or the master cylinder  20 . 
         [0034]    Further, a normal open type solenoid valve  47  (hereinafter, a TC valve) for a traction control system (TCS) is installed in the main flow path  47   a  which connects the master cylinder  20  to an outlet of the pump  44 . The TC valve  47  usually maintains an open state and, during a general braking using the brake pedal  10 , transfers brake hydraulic pressure generated from the master cylinder  20  to the wheel cylinder  30  through the main flow path  47   a.    
         [0035]    Further, the auxiliary flow path  48   a  is branched from the main flow path  47   a  to guide brake oil discharged from the master cylinder  20  to be suctioned at the inlet of the pump  44 , and a shuttle valve  48  is installed on the auxiliary flow path  48   a  so that the brake oil is only introduced into the inlet of the pump  44 . The shuttle valve  48  which is electrically operated is installed in the middle of the auxiliary flow path  48   a , is usually closed, and is operated to be open in a TCS mode. 
         [0036]    Meanwhile, the unmentioned reference number ‘ 49 ’ is a check valve installed at a suitable position in a flow path for preventing a backflow of brake oil, the reference number ‘ 50 ’ is a pressure sensor which detects a brake pressure transferred to the TC valve  47  and the shuttle valve  48 , and the reference number ‘ 51 ’ is an orifice. 
         [0037]    When braking is performed in the hydraulic brake system described above, a pressure pulsation is generated from a hydraulic pressure pumped from the pump  44  according to operation of the motor  45 . Thus, according to one embodiment of the present disclosure, a pulsation damping device  100  connected to the outlet of the pump  44  of each of the hydraulic circuits  40 A and  40 B is provided for attenuating a pressure pulsation. 
         [0038]      FIG. 2  is a perspective view of an assembly illustrating a state in which a pulsation damping device provided in a hydraulic brake system according to an exemplary embodiment of the present disclosure is being assembled in a modulator block,  FIG. 3  is a perspective view of the assembly shown in  FIG. 2 , and  FIG. 4  is a cross-sectional view illustrating a flow of brake oil whose pressure pulsation is attenuated by the pulsation damping device of the hydraulic brake system. 
         [0039]    Referring to  FIGS. 2 to 4 , the pulsation damping device  100  according to one embodiment of the present disclosure is provided at an inport  102  in which brake oil discharged from the pump  44  (see  FIG. 1 ) is introduced and a bore  101  which communicates with an outport  103  through which brake oil is discharged. Here, as the pulsation damping device  100  is provided in the main flow path  47   a  (see  FIG. 1 ), the inport  102  is connected to the main flow path  47   a  connected to the outlet the pump  44 , and the outport  103  is connected to the main flow path  47   a  connected to the master cylinder  20 . The pulsation damping device  100  includes a damping member  110  inserted into and provided in the bore  101  and a sleeve  130  which surrounds a stopper member  120  inserted into the damping member  110  and blocks an opening of the bore  101  whose one side is open and the damping member  110  and is coupled to the stopper member  120 . 
         [0040]    The damping member  110  is formed in a hollow cylindrical shape, of which one side is open so that a damping space  111  is formed therein, and is inserted into the bore  101 . More specifically, an outer circumferential surface of the damping member  110  is inserted to be spaced a predetermined gap from the bore  101 . Here, a concave-convex portion  113  is formed on the outer circumferential surface of the damping member  110  in a longitudinal direction. When the damping member  110  is coupled to the sleeve  130 , the concave-convex portion  113  forms an auxiliary damping space  114  between the sleeve  130  and the concave-convex portion  113 . The auxiliary damping space  114  will be described again below. 
         [0041]    The stopper member  120  is coupled to an opening of the sleeve  130 . A lower portion of the stopper member  120  is accommodated in the sleeve  130 , and an upper portion of the stopper member  120  protrudes above the sleeve  130 . 
         [0042]    Further, the stopper member  120  includes a first coupling portion which is coupled to the damping member  110  for sealing the damping space  111  and a second coupling portion which is coupled to the sleeve  130  for sealing between the damping space  111  and the auxiliary damping space  114 . Here, the damping member  110  may be positioned under the second coupling portion. 
         [0043]    Meanwhile, a coupling protrusion  112  is formed in a hollow portion of the damping member  110  coupled to the stopper member  120 . As the coupling protrusion  112  is for maintaining a close coupling relationship with the stopper member  120 , the coupling protrusion  112  serves to prevent leakage of brake oil between the stopper member  120  and the damping member  110 . Such coupling structure of the coupling protrusion  112  and the stopper member  120  will be described again below. The damping member  110  is formed of a rubber material and may be elastically deformed. 
         [0044]    The stopper member  120  is installed to be coupled to the damping member  110  to block one open end of the bore  101 . A flow path  126  by which the inport  102  and the outport  103  are in communication with the damping space  111  is formed in the stopper member  120 . Here, although the flow path  126  can be formed in any type as long as the inport  102  and the outport  103  communicate with the damping space  111 , it is preferable that the flow path  126  be positioned to be spaced apart from the inport  102  and the outport  103  so that brake oil detours to be discharged to the outport  103  for effective pulsation damping. The stopper member  120  includes an insertion portion  121  to be inserted into the hollow portion of the damping member  110  and a cap portion  125  integrally formed with the insertion portion  121  to block the one open end of the bore  101 . 
         [0045]    The insertion portion  121  is inserted into the hollow portion of the damping member  110 , and the damping space  111  is thus formed in the damping member  110 . Referring to the drawings, one side of the insertion portion  121  is closely coupled to the inside of the damping member  110 , and the other side is coupled to the sleeve  130  to be described below. Accordingly, a first coupling groove  122  to be coupled to the damping member  110  and a second coupling groove  123  to be coupled to the sleeve  130  are formed in the stopper member  120 . 
         [0046]    The first coupling groove  122  is formed to have a concave shape on an outer circumferential surface of the insertion portion  121 . At least one first coupling groove  122  may be formed in the insertion portion  121 . The coupling protrusion  112  which fits the first coupling groove  122  is formed on an inner circumferential surface of the damping member  110  into which the insertion portion  121  is inserted. That is, the damping member  110  is coupled to the stopper member  120  by inserting the coupling protrusion  112  into the first coupling groove  122 . Referring to the drawings, in addition to coupling of the first coupling groove  122  with the coupling protrusion  112 , a complementary structure, i.e., a structure having a concave groove formed in the damping member  110  and a part of the insertion portion  121  inserted into and coupled to the groove, may also maintain a close coupling state between the damping member  110  and the stopper member  120 . Thus, leakage of brake oil between the stopper member  120  and the damping member  110  can be prevented. 
         [0047]    The second coupling groove  123  is formed around the other side of the insertion portion  121 , i.e., above the first coupling groove  122 . The second coupling groove  123  is formed along a perimeter of an outer surface of the insertion portion  121 . Here, a hook portion  133 , which enters the second coupling groove  123  and is deformed to be caught at the second coupling groove  123 , is provided on the sleeve  130 . That is, after the stopper member  120  enters the sleeve  130 , the hook portion  133  is formed by deforming the stopper member  120 , and thus the stopper member  120  and the sleeve  130  may be fixed. Thus, since the stopper member  120  is installed to be in contact with each of the damping member  110  and the sleeve  130 , the stopper member  120  provides sealing between the damping space  111  and the auxiliary damping space  114 . 
         [0048]    The cap portion  125  is installed to block the one open end of the bore  101 . That is, the cap portion  125  prevents oil introduced into the bore  101  from leaking to the outside. The flow path  126  by which the inport  102  and the outport  103  are in communication with the damping space  111  is formed in the cap portion  125 . Here, the flow path  126  may be formed with a first flow path  126   a  which connects the inport  102  to the outport  103  and a second flow path  126   b  which connects the first flow path  126   a  to the damping space  111 . 
         [0049]    Further, a space through which brake oil is introduced and discharged may be formed between the stopper member  120  and the bore  101  in a region in which the first flow path  126   a  passing through the stopper member  120  is formed. 
         [0050]    In addition, the bore  101  includes a lower bore in which a lower portion of the sleeve  130  is accommodated and an upper bore in which a shoulder portion of the sleeve  130  is accommodated, inner diameter of the lower bore is provided to be smaller than inner diameter of the upper bore, and a space through which brake oil is introduced and discharged may be formed between the sleeve  130  and the upper bore in a region in which the inport  102  and the outport  103  are provided. 
         [0051]    The sleeve  130  surrounds the damping member  110  and is pressed to be inserted into and coupled to the stopper member  120 . Here, as described above, the sleeve  130  includes the hook portion  133  which is deformed to be coupled to the second coupling groove  123 . Since the structure of the hook portion  133  is described above, a detailed description thereof will be omitted. Further, the sleeve  130  is pressed to be inserted into and installed on the bore  101  so that brake oil flows from the inport  102  to the outport  103  through the flow path  126  formed in the stopper member  120 . Since the sleeve  130  surrounds the damping member  110  and is coupled to the stopper member  120 , the pulsation damping device  100  according to one embodiment of the present disclosure may be provided as one assembly. Accordingly, the pulsation damping device  100  may be easily installed in the bore  101 . 
         [0052]    Meanwhile, since the sleeve  130  is formed to be in contact with and surround an outer surface of the damping member  110 , the auxiliary damping space  114  is formed between the sleeve  130  and the concave-convex portion  113  of the damping member  110 . That is, a concave portion of the concave-convex portion  113  is formed as the auxiliary damping space  114 . Thus, a pressure pulsation of high hydraulic pressure introduced from the inport  102  is first attenuated by the damping space  111 , the pressure pulsation is attenuated a second time by the auxiliary damping space  114 , and attenuating of the pressure pulsation is thus effectively performed. Further, since the sleeve  130  is provided to surround the damping member  110 , durability of the damping member  110  is improved. 
         [0053]    Further, the sleeve  130  further includes the shoulder portion which extends from the opening. The shoulder portion is provided to extend from an end of the opening of the sleeve  130  to the outside. 
         [0054]    In addition, the stopper member  120  includes a step corresponding to the shoulder portion. That is, the stopper member  120  includes a portion which is inserted into an inner circumferential surface of the shoulder portion and a portion which is pressed against an upper surface of the shoulder portion. 
         [0055]    Subsequently, a state in which a pressure pulsation is attenuated by the pulsation damping device will be described. 
         [0056]    Brake oil discharged at high pressure by pumping of the pump  44  is transferred to the pulsation damping device  100  through the inport  102 . The brake oil introduced through the inport  102  flows into the damping member  110 , i.e., the damping space  111 , through the flow path  126  formed in the stopper member  120 , a pressure pulsation of the brake oil is attenuated by elastically deforming the damping member  110 , and the brake oil is discharged to the outport  103 . Here, the pressure pulsation is attenuated by mitigating impacts by the damping member  110  formed of a rubber material, and the pressure pulsation is also more effectively attenuated by the auxiliary damping space  114  formed between the sleeve  130  and the damping member  110 . 
         [0057]    As is apparent from the above description, it is advantageous that a pressure pulsation can be attenuated because the pulsation damping device of a hydraulic brake system according to one embodiment of the present disclosure includes a damping member in which a damping space is formed, and compared to a conventional case, installation time and cost can also be reduced because the damping member is provided with one assembly having a simple structure. 
         [0058]    Further, it is advantageous that a pressure pulsation can be effectively attenuated by providing a separate auxiliary damping space between a damping member and a sleeve and, since damage is prevented by limiting excessive deformation even at high pressure, function degradation caused by a decrease in durability can be prevented even when used for a long time. 
         [0059]    Meanwhile, it is advantageous that coupling is easy because a hook portion is coupled with a stopper member by deforming a sleeve, and assembly is also easy because the stopper member and a damping member to be elastically deformed are assembled in a coupling structure having a groove and a protrusion. 
         [0060]    As described above, while the present disclosure has been described with reference to specific embodiments and drawings, the present disclosure is not limited thereto. It should be clear to those skilled in the art that various modifications and alterations may be made without departing from the spirit and scope of the present disclosure and equivalents of the appended claims. 
         [0000]    
       
         
               
             
               
               
               
               
             
           
               
                   
               
               
                 [Reference Numerals] 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 100:  
                 PULSATION  
                 102:  
                 INPORT 
               
               
                   
                 DAMPING DEVICE 
                 110:  
                 DAMPING MEMBER 
               
               
                 103:  
                 OUTPORT 
                 112:  
                 COUPLING PROTRUSION 
               
               
                 111:  
                 DAMPING SPACE 
                 114:  
                 AUXILIARY DAMPING  
               
               
                 113:  
                 CONCAVE-CONVEX  
                   
                 SPACE 
               
               
                   
                 PORTION 
                 122:  
                 FIRST COUPLING  
               
               
                 120:  
                 STOPPER MEMBER 
                   
                 GROOVE 
               
               
                 123:  
                 SECOND COUPLING  
                 126:  
                 FLOW PATH 
               
               
                   
                 GROOVE 
                 133:  
                 HOOK PORTION 
               
               
                 130:  
                 SLEEVE