Abstract:
A solenoid valve for a brake system enabling miniaturization of the valve and having an improved configuration to facilitate assembly and production of the valve. The solenoid valve includes an armature provided at one end thereof with an opening/closing member, a valve housing including a hollow first valve block fixed in a modulator block and a second valve block disposed below the first valve block and having an inlet for introduction of fluid, a valve seat installed in the first valve block and having a flow-hole to be opened or closed by the opening/closing member and a hollow extending longitudinally from the flow-hole, and an orifice sleeve located in the second valve block to define a fluid discharge passage and having an orifice formed in one end thereof to communicate with the hollow of the valve seat.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a solenoid valve for a brake system, and more particularly, to a solenoid valve for a brake system having an improved assembly configuration of constituent elements thereof. 
     2. Description of the Related Art 
     Generally, a vehicular hydraulic brake slows or stops a vehicle by applying hydraulic pressure to a master cylinder according to operation of a brake pedal. In this case, when a greater braking force than a stoppage frictional force between a tire and a road surface is applied to the tire, there occurs a tire slippage phenomenon on the road surface. 
     However, since a coefficient of kinetic friction is less than a coefficient of static friction, it is necessary to prevent the tire slippage phenomenon in order to achieve optimal braking. In addition, it is necessary to prevent a steering lock phenomenon that prevents steering during operation of the brake. 
     An anti-lock brake system serves to prevent the above-described phenomenon by controlling hydraulic pressure applied to a master cylinder. The anti-lock brake system basically includes a plurality of solenoid valves, an ECU to control the solenoid valves, an accumulator, and a hydraulic pump. 
     The solenoid valves are classified into normal open type solenoid valves, which are arranged at the upstream side of a hydraulic brake and are normally kept in an opened state, and normal close type solenoid valves which are arranged at the downstream side of the hydraulic brake and are normally kept in a closed state. 
       FIG. 1  is a sectional view illustrating a configuration of a conventional normal close type solenoid valve. As shown in  FIG. 1 , the conventional normal close type solenoid valve (hereinafter, referred to as a “solenoid valve”) is installed in a modulator block  1  to enhance responsiveness. The modulator block  1  is formed with a bore  2  by cutting for installation of the solenoid valve. 
     A first valve block  3  is fitted in a hollow first valve block  3 . A cylindrical guide sleeve  4  is coupled to one end of the first valve block  3 , and an armature  5  is disposed in the guide sleeve  4 . Also, a valve core  6  is fitted into an open end of the guide sleeve  4  and serves to drive the armature  5 . 
     A plunger  5   a  is integrally provided at one end of the armature  5 , and serves to open or close a flow-hole  7   a  of a valve seat  7  according to sliding movement of the armature  5 . A return spring  5   b  is inserted between the other end of the armature  5  and the valve core  6 . The return spring  5   b  elastically supports the armature  5  such that the armature  5  normally keeps the flow-hole  7   a  in a closed state. 
     An O-ring  8  is fitted around the first valve block  3  to seal a gap between an entrance-side and an exit-side of the solenoid valve. An orifice plate  9  is coupled to a lower end of the first valve block  3 . The orifice plate  9  has an orifice  9   a  to regulate a flow rate of fluid to be discharged from the solenoid valve. 
     In addition, an exciting coil (not shown) is installed around the guide sleeve  4  and the valve core  6 , to cause sliding movement of the armature  5 . 
     In operation of the above-described solenoid valve, when power is applied to the exciting coil, a magnetic force is generated between the valve core  6  and the armature  5 . As the armature  5  is moved toward the valve core  6  by the magnetic force, the flow-hole  7   a  of the valve seat  7  is opened. On the other hand, since no magnetic force is exerted when no power is applied to the exciting coil, the armature  5  is returned to an original position thereof by an elastic force of the return spring  5   b , closing the flow-hole  7   a.    
     As described above, the conventional solenoid valve is constituted such that constituent elements thereof are arranged about the first valve block  3 , and thus, the first valve block  3  must have installation spaces for the valve seat  7 , O-ring  8  and orifice plate  9  and inlet and outlet holes  3   a  and  3   b  for fluid-flow. Therefore, the first valve block  3  has problems of a large overall size and complicated configuration. The complicated configuration of the first valve block  3  inevitably entails a complex manufacturing process, and results in deterioration of product competitiveness due to an increased production price of the valve. 
     SUMMARY OF THE INVENTION 
     Therefore, it is an aspect of the invention to provide a solenoid valve for a brake system, which enables miniaturization of the valve and has an improved configuration to facilitate assembly and production of the valve. 
     Additional aspects and/or advantages of the invention 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 invention. 
     In accordance with an aspect of the invention, the above and/or other aspects can be achieved by the provision of a solenoid valve for a brake system, comprising: an armature provided at one end thereof with an opening/closing member; a valve housing including a hollow first valve block fixed in a modulator block and a second valve block disposed below the first valve block and having an inlet for introduction of fluid; a valve seat installed in the first valve block and having a flow-hole to be opened or closed by the opening/closing member and a hollow extending longitudinally from the flow-hole; and an orifice sleeve located in the second valve block to define a fluid discharge passage and having an orifice formed in one end thereof to communicate with the hollow of the valve seat. 
     The first valve block may include a longitudinally-extending connection passage defined therein. 
     A lower end of the first valve block may be press-fitted in one end of the second valve block, and the other end of the second valve block may be supported by the orifice sleeve. 
     The orifice sleeve may include a bent portion to receive the other end of the second valve block. 
     One end of the orifice sleeve may be press-fitted in the hollow of the valve seat. 
     The other end of the orifice sleeve may be press-fitted in the modulator block. 
     In accordance with another aspect of the invention, the above and/or other aspects can be achieved by the provision of a solenoid valve for a brake system, comprising: an armature provided at one end thereof with an opening/closing member; a valve housing including a hollow first valve block fixed in a modulator block and a second valve block disposed below the first valve block and having an inlet for introduction of fluid; and an orifice sleeve located in the valve housing to define a fluid discharge passage and having an orifice formed in one end thereof so as to be opened or closed by the opening/closing member. 
     The first valve block may include a longitudinally-extending connection passage defined therein. 
     A lower end of the first valve block may be press-fitted in one end of the second valve block, and the other end of the second valve block may be supported by the orifice sleeve. 
     The orifice sleeve may include a bent portion to receive the other end of the second valve block. 
     One end of the orifice sleeve may be press-fitted in a hollow of the first valve block. 
     The other end of the orifice sleeve may be press-fitted in the modulator block. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects and advantages of the exemplary embodiments of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, of which: 
         FIG. 1  is a sectional view illustrating a configuration of a conventional normal close type solenoid valve; 
         FIG. 2  is a sectional view illustrating a configuration of a solenoid valve for a brake system according to an embodiment of the present invention; and 
         FIG. 3  is a sectional view illustrating a configuration of a solenoid valve for a brake system according to another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The embodiments are described below to explain the present invention by referring to the figures. 
       FIG. 2  is a sectional view illustrating a configuration of a solenoid valve for a brake system according to an embodiment of the present invention. As shown in  FIG. 2 , the solenoid valve for a brake system according to the present invention is installed in a valve block  10 . The valve block  10  is formed with a valve bore  11  by cutting for installation of constituent elements of the valve. 
     A hollow valve housing  100  of the solenoid valve is fitted in the valve bore  11 . The valve housing  100  includes a first valve block  20  to which a cylindrical guide sleeve  30  is coupled, and a second valve block  70  disposed below the first valve block  20  and having an inlet  71  for introduction of fluid. 
     An armature  40  is disposed in the guide sleeve  30 , and a valve core  50  to drive the armature  40  is coupled to an open end of the guide sleeve  30 . 
     A ball-shaped opening/closing member  41  is installed at one end of the armature  40 . The opening/closing member  41  opens or closes a flow-hole  61  of a valve seat  60  according to sliding movement of the armature  40 . Also, a return spring  42  is inserted between the other end of the armature  40  and the valve core  50 , and elastically supports the armature  40  such that the armature  40  normally keeps the flow-hole  61  in a closed state. 
     The valve seat  60  is fitted in the first valve block  20 . The valve seat  60  has the flow-hole  61  to be opened or closed by the opening/closing member  41  and a hollow  62  extending downward from the flow-hole  61 . The first valve block  20  is internally formed with a connection passage  21 , to allow fluid, introduced into the second valve block  70  through an inlet  71  of the second valve block  70 , to flow toward the flow-hole  61 . 
     The hollow second valve block  70  is installed below the first valve block  20 . An upper end of the second valve block  70  adjacent to the first valve block  20  is formed with a stepped portion  72 , and a lower end of the first valve block  20  is press-fitted in the stepped portion  72 . This configuration can prevent the fluid introduced into the second valve block  70  from leaking toward the valve bore  11 . 
     The inlet  71  of the second valve block  70  corresponds to an entrance of the solenoid valve. The inlet  71  is provided with a filter  71   a  to filter impurities contained in the fluid before introduction thereof into the second valve block  70 . 
     An orifice sleeve  80 , formed by a deep-drawing process, is installed in the second valve block  70 . One end of the orifice sleeve  80  is press-fitted in the hollow  62  of the valve seat  60 , and the other end is press-fitted in the valve bore  11 . The end of the orifice sleeve  80 , press-fitted in the valve seat  60 , is formed with an orifice  81  to regulate a flow rate of fluid. The orifice  81  has a cross sectional area determined according to characteristics of a vehicle. The other end of the orifice sleeve  80 , press-fitted in the valve bore  11 , is opened, forming an outlet  82  that corresponds to an exit of the solenoid valve. 
     The above-described orifice sleeve  80  divides the interior of the second valve block  70  into an introduction passage  70   a  and a discharge passage  70   b . The introduction passage  70   a  allows the fluid, introduced into the second valve block  70 , to flow toward the flow-hole  61 , and the discharge passage  70   b  allows the fluid, having passed through the flow-hole  61 , to flow toward the outlet  82 . 
     The second valve block  70  has a protrusion  73  formed at an inner surface thereof to protrude horizontally toward the orifice sleeve  80 . The protrusion  73  comes into close contact with an outer surface of the orifice sleeve  80 . 
     The second valve block  70  further has a small-diameter lower end portion  74 , and the orifice sleeve  80  has a bent portion  83  configured to receive the small-diameter lower end portion  74  of the second valve block  70 . The bent portion  83  is formed by primarily bending an end of the orifice sleeve  80  to extend horizontally, and then, secondarily bending the horizontally-extended end upward to extend vertically. The small-diameter lower end portion  74  of the second valve block  70  is press-fitted in the bent portion  83  to thereby be supported by the orifice sleeve  80 . This configuration can prevent the fluid in the introduction passage  70   a  from leaking toward the outlet  82  along the outer surface of the sleeve  80 . 
       FIG. 3  is a sectional view illustrating a configuration of a solenoid valve for a brake system according to another embodiment of the present invention. In the following description, parts or configurations having extremely similar functions as the above-described embodiment are designated by the same reference numerals, and a detailed description thereof is omitted. 
     Referring to  FIG. 3  illustrating the solenoid valve for a brake system according to another embodiment of the present invention, the valve seat  60  is removed from the interior of the first valve block  20 , and an orifice  81 ′ formed at an orifice sleeve  80 ′ can function as the flow-hole  61  of the valve seat  60  shown in  FIG. 2 . Accordingly, the present embodiment has a feature of further simplifying the interior configuration of the valve housing  100 . 
     Specifically, the orifice sleeve  80 ′ has an elongated tube form having a longer length than a width thereof, and is installed in an interior space of the valve housing  100 . One end of the orifice sleeve  80 ′ is press-fitted in the first valve block  20 , and the other end is press-fitted in the second valve block  70 . 
     The orifice sleeve  80 ′ divides the interior space of the valve housing  100  into a connection passage  21 ′ communicating with the inlet  71 , and a discharge passage  70   b  communicating with the outlet  82 . 
     The orifice  81 ′ is formed in the end of the orifice sleeve  80 ′ press-fitted in the first valve block  20 , to enable communication between the connection passage  21 ′ and the discharge passage  70   b.    
     The orifice  81 ′ is opened or closed by the ball-shaped opening/closing member  41  provided at one end of the armature  40 . Specifically, the opening/closing member  41  is disposed above the orifice sleeve  80 . When the armature  40  pushes the opening/closing member  41  toward the orifice sleeve  80 ′, the opening/closing member  41  comes into close contact with the orifice sleeve  80 ′, closing the orifice  81 ′. On the other hand, when the armature  40  moves upward and does not apply pressure to the opening/closing member  41 , the opening/closing member  41  is spaced apart from the orifice sleeve  80 ′ by interior oil pressure of the valve housing  10 , opening the orifice  81 ′. 
     With the above-described operation, oil, introduced through the inlet  71  of the valve housing  100 , moves to the orifice  81 ′ along the connection passage  21 ′, and then, moves along the discharge passage  70   b  after passing through the orifice  81 ′. 
     As described above, the solenoid valve for a brake system according to the present invention can be constructed by assembling the first valve block  20 , second valve block  70  and orifice sleeve  80  or  80 ′. With this configuration, the respective constituent elements of the solenoid valve can be simplified in configuration and be easily assembled, and also, the solenoid valve can prevent leakage of fluid without a sealing member such as an O-ring. 
     As apparent from the above description, the present invention provides a solenoid valve for a brake system, which adopts a valve housing consisting of first and second valve blocks having simplified configurations and an orifice sleeve, instead of densely installing constituent elements around a single valve block, thereby enabling simplification in the configuration of respective elements, and preventing leakage of fluid in the valve even without a sealing member such as an O-ring. As a result, the present invention has the effect of simplifying the process of manufacturing products therefrom and reducing manufacturing costs. 
     Although embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.