Patent Abstract:
A damper device for a hydraulic control valve includes: a valve body; a damper oil chamber to which one end surface of a spool is faced; an oil reservoir chamber which is adjacent to the damper oil chamber with a partition wall therebetween; and an orifice provided in the partition wall to allow an upper portion of the damper oil chamber to communicate with the oil reservoir chamber. The damper oil chamber and the oil reservoir chamber are disposed in the valve body. The oil reservoir chamber is constructed by closing an opening of a recessed portion formed on an undersurface of the valve body with a top surface of the support member for supporting the valve body. In order to work the orifice in the partition wall by drilling from the opening of the recessed portion, an axis of the orifice is disposed to pass through the opening of the recessed portion. Thus, it is possible to eliminate need for post-treatment after working the orifice, thereby reducing the cost.

Full Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to an improvement of a damper device for a hydraulic control valve, comprising: a valve body in which a spool driven by an output force of a linear solenoid unit is fitted; a damper oil chamber to which one end surface of a spool is faced, the damper oil chamber being disposed in the valve body; an oil reservoir chamber which is adjacent to the damper oil chamber with a partition wall therebetween, the oil reservoir chamber being disposed in the valve body; and an orifice provided in the partition wall to allow an upper portion of the damper oil chamber to communicate with the oil reservoir chamber; the oil reservoir chamber being constructed by closing an opening of a recessed portion formed on an undersurface of the valve body with a top surface of the support member for supporting the valve body.  
         [0003]     2. Description of the Related Art  
         [0004]     Such a damper device for a hydraulic control valve is already known as disclosed in, for example, Japanese Patent Application Laid-open No. 2002-130513.  
         [0005]     In the conventional damper device for the hydraulic control valve, the orifice, which is provided in the partition wall between the damper oil chamber and the oil reservoir chamber, is worked by a drill which penetrates through the outer wall of the oil reservoir chamber. Therefore, it is necessary to close a castoff hole remained in the outer wall of the oil reservoir chamber, with a closing plug after the orifice is worked. That is, a troublesome post-treatment is required after working the orifice.  
       SUMMARY OF THE INVENTION  
       [0006]     The present invention has been achieved in view of the above circumstances, and has an object to provide a damper device for a hydraulic control valve which eliminates need for the post-treatment after working the orifice, thereby reducing the cost.  
         [0007]     In order to attain the above-described object, according to a first feature of the present invention, there is provided a damper device for a hydraulic control valve, comprising: a valve body in which a spool driven by an output force of a linear solenoid unit is fitted; a damper oil chamber to which one end surface of a spool is faced, the damper oil chamber being disposed in the valve body; an oil reservoir chamber which is adjacent to the damper oil chamber with a partition wall therebetween, the oil reservoir chamber being disposed in the valve body; and an orifice provided in the partition wall to allow an upper portion of the damper oil chamber to communicate with the oil reservoir chamber; the oil reservoir chamber being constructed by closing an opening of a recessed portion formed on an undersurface of the valve body with a top surface of the support member for supporting the valve body; wherein the orifice of the partition wall is placed so that an axis of the orifice passes through the opening of the recessed portion.  
         [0008]     The support member corresponds to a transmission case  2  in embodiments of the present invention which will be described later.  
         [0009]     In addition to the first feature, according to a second feature of the present invention, the damper device further comprising a drain passage which discharges surplus oil of the oil reservoir chamber is opened above the orifice.  
         [0010]     In addition to the second feature, according to a third feature of the present invention, a mounting surface of the support member to the valve body is inclined so that the axis of the orifice is closer to a horizontal line.  
         [0011]     In addition to the second or third feature, according to a fourth feature the present invention, the drain passage comprises a drain hole which is provided in the support member and opened to the top surface, and a drain pipe which rises from an opening of the drain hole and opened above the orifice.  
         [0012]     With the first feature of the present invention, the orifice of the partition wall can be worked by drilling along the axis of the orifice passing through the opening of the recessed portion of the valve body. That is, the castoff hole is not necessary in the process of working the orifice. Accordingly, it is not necessary to perform a troublesome post-treatment of applying a closing plug or the like after working the orifice, thus contributing to reduction of the cost.  
         [0013]     With the second feature of the present invention, the oil, which is discharged to the oil reservoir chamber from the damper oil chamber through the orifice, can be stored up to the opening of the drain oil passage, which is located at position above the orifice, and therefore the orifice can be submerged in the oil of the oil reservoir chamber. Consequently, the damper oil chamber is always reliably filled with oil, thereby ensuring a good vibration suppressing function of the damper oil chamber.  
         [0014]     With the third feature of the present invention, the axis of the orifice, which is opened into the upper portion of the damper oil chamber, can be made closer to the horizontality by the extremely simple means of inclining the surface mounting the support member to the valve body. Therefore, the discharging efficiency of the air bubbles generated in the damper oil chamber from the orifice is enhanced, thus contributing to stabilization of the vibration suppressing function of the damper oil chamber.  
         [0015]     With the fourth feature of the present invention, oil can be stored so that the orifice is submerged in the oil owing to the presence of the drain pipe. Therefore, the oil reservoir chamber, and thus the valve body, can be made compact while ensuring good vibration suppressing function of the damper oil chamber. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]      FIG. 1  is a bottom view of a hydraulic control valve according to a first embodiment of the present invention.  
         [0017]      FIG. 2  is an enlarged sectional view taken along the line  2 - 2  in  FIG. 1 .  
         [0018]      FIG. 3  is an enlarged sectional view taken along the line  3 - 3  in  FIG. 1 .  
         [0019]      FIG. 4  is a sectional view taken along the line  3 - 3  in  FIG. 1 .  
         [0020]      FIG. 5  is a view corresponding to  FIG. 4 , showing a second embodiment of the present invention.  
         [0021]      FIG. 6  is a view corresponding to  FIG. 3 , showing a third embodiment of the present invention.  
         [0022]      FIG. 7  is a view corresponding to  FIG. 3 , showing a fourth embodiment of the present invention.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]     The above-mentioned object, other objects, features, and advantages of the present invention will become clear from the detailed description of a preferred embodiment with reference to the accompanying drawings.  
         [0024]     The first embodiment of the present invention shown in  FIG. 1  to  FIG. 4  will be explained.  
         [0025]     Referring to  FIG. 1 , a hydraulic control valve  1  is for controlling clutch hydraulic pressure in, for example, an automatic transmission for an automobile, and is constituted of a linear solenoid unit S and a valve unit V. A valve body  20  of the valve unit V is joined with a bolt  5  to a top surface  2   a  of a transmission case  2  (see  FIG. 4 ) of an automobile.  
         [0026]     As shown in  FIG. 2 , the linear solenoid unit S includes: a housing  3  made of a magnetic material in a bottomed cylindrical shape with one end opened; a coil assembly  4  housed in this housing  3 ; a cylindrical yoke  6  integrally connected to a closed end wall of the housing  3  and placed inside the coil assembly  4 ; a fixed core  7  connected to the open end of the housing  3 , and placed inside the coil assembly  4  to oppose to the yoke  6  with a predetermined space from the yoke  6 ; and a movable core  8  slidably fitted in the yoke  6  and the fixed core  7 . The coil assembly  4  is constituted of a bobbin  9  made of a synthetic resin, a coil  10  which is wound around the bobbin  9 , and a coil case  11  made of a synthetic resin formed to house the bobbin  9  and the coil  10 . A coupler  12  protruding outside the housing  3  is integrally connected to one end portion of the coil case  11 , and a connecting terminal  13  leading to the coil  10  is placed in the coupler  12 .  
         [0027]     An opposing surface of the yoke  6  to the fixed core  7  is formed perpendicularly to the axis of the yoke  6 . An opposing surface of the fixed core  7  to the yoke  6  is formed into a conical shape.  
         [0028]     An output rod  14  penetrating through a central portion of the movable core  8  is fixed to the movable core  8 . One end portion of this output rod  14  is slidably supported in a bag-shaped first bearing hole  15   1  provided in the closed end wall of the housing  3  via a first bush  16   1 . The other end portion of the output rod  14  is slidably supported in a second bearing hole  15   2 , which penetrates through a central portion of the fixed core  7 , via a second bush  16   2 .  
         [0029]     Thus, an electromagnetic thrust force proportional to a current value passing through the coil  10  can be applied to the output rod  14  via the movable core  8 .  
         [0030]     The first bush  16   1  is fixed to an inner peripheral surface of the first bearing hole  15   1  by press fitting. A first communication groove  17   1  is provided in the axial direction on an outer peripheral surface of the first bush  16   1  to provide communication between its opposite ends surfaces. A second bush  16   2  is fixed to an inner peripheral surface of the second bearing hole  15   2  by press fitting. A second communication groove  17   2  is also provided in the axial direction on an outer peripheral surface of this second bush  16   2  to provide communication between its opposite ends surfaces. A third communication groove  17   3  is provided in the axial direction on an outer peripheral surface of the movable core  8  to provide communication between its end surfaces of the movable core  8 .  
         [0031]     Next, as shown in  FIG. 3 , the valve unit V is constructed by a valve body  20  connected by crimping to the housing  3  at the side of the fixed core  7 , a spool  22  which is fitted into a valve hole  21  formed in this valve body  20  coaxially with the output rod  14  and abuts to a front end of the output rod  14 , a return spring  23  for biasing this spool  22  in its retreating direction, namely, in a direction to abut to the output rod  14 , and a plug  24  which is press-fitted into the valve body  20  and supports an outer end of the return spring  23 . A set load of the return spring  23  is adjusted in accordance with press fitting depth of the plug  24  into the valve body  20 .  
         [0032]     The spool  22  is provided with a first land portion  25   1 , a first annular groove portion  26   1 , a second land portion  25   2 , a second annular groove portion  26   2  and a third land portion  25   3  in order from the side of the linear solenoid unit S. The first and the second land portions  25   1  and  25   2  are formed to have the same diameter, and the third land portion  25   3  is formed to have a diameter slightly larger than that of the second land portion  25   2 .  
         [0033]     Meanwhile, the valve hole  21  of the valve body  20  is provided with an operating chamber  30  which the abutting portion of the output rod  14  and the spool  22  faces, a first annular land portion  31   1  which is adjacent to this operating chamber  30  and to which the first land portion  25   1  is always slidably fitted, a second annular land portion  31   2  which the opposing end portions of the first land portion  25   1  and the second land portion  25   2  are alternately fitted to and separated from, a third annular land portion  31   3  to which the second land portion  25   2  is always slidably fitted, a fourth annular land portion  31   4  to which the third land portion  25   3  is always slidably fitted, a supply oil chamber  32  placed to be sandwiched between the first and the second annular land portions  31   1  and  31   2 , an output oil chamber  33  which is placed inside the second annular land portion  31   2  to be sandwiched between the first and the second land portions  25   1  and  25   2  of the spool  22 , a drain oil chamber  34  which is placed to be sandwiched between the second and the third annular land portions  31   2  and  31   3 , a reaction force oil chamber  35  which a border portion of the second and the third annular land portions  31   2  and  31   3  including the second annular groove portion  26   2  faces, and a damper oil chamber  36  which both opposite ends surfaces of the spool  2  and the plug  24  face. The return spring  23  is housed in this damper oil chamber  36 .  
         [0034]     An outer peripheral surface of the third land portion  25   3  is constructed by a cylindrical slide surface  25   3a  which is fitted to the fourth annular land portion  31   4 , and a taper surface  25   3b  which has a diameter increasing from the cylindrical slide surface  25   3a  to the reaction force oil chamber  35 . A slide gap g which can leak and supply oil to the damper oil chamber  36  from the reaction force oil chamber  35  is provided between the cylindrical slide surface  25   3a  of the third land portion  25   3  and the fourth annular land portion  31   4 .  
         [0035]     The valve body  20  is further provided with a supply port  37  continuing into the supply oil chamber  32 , an output port  38  continuing into the output oil chamber  33 , a drain port  39  continuing into the drain oil chamber  34 , and a breather port  40  continuing into the operating chamber  30 . The supply port  37  is connected to a hydraulic pump  42  as a hydraulic pressure source via a supply oil passage  41  of the transmission case  2 . The output port  38  is connected to an output oil passage  43  directly leading to a hydraulic operating portion  44  such as a clutch for automatic transmission. The drain port  39  and the breather port  40  are opened into an oil reservoir chamber  49  (see  FIG. 1  and  FIG. 4 ), which will be described later, inside the valve body  20 . The hydraulic pump  42  is driven by an engine not shown.  
         [0036]     The output oil chamber  33  communicates with the reaction force oil chamber  35  via a feedback oil passage  48  formed in the spool  22 .  
         [0037]     Thus, if the spool  22  is held at the retreated position by the biasing force of the return spring  23  when the linear solenoid unit S is not energized, the spool  22  provides communication between the supply port  37  and the output port  38 . That is, the hydraulic control valve  1  is of a normally open type.  
         [0038]     As shown in  FIG. 1  and  FIG. 4 , the valve body  20  is provided with the oil reservoir chamber  49  around the damper oil chamber  36 . The oil reservoir chamber  49  is defined by closing a downward opening of a recessed portion  51  formed in an undersurface of the valve body  20  with the top surface  2   a  of the transmission case  2  to which the valve body  20  is joined. An uppermost portion of the damper oil chamber  36  is allowed to communicate with the oil reservoir chamber  49  via an orifice  50 , so that the oil discharged from the damper oil chamber  36  through the orifice  50  is stored in the oil reservoir chamber  49 .  
         [0039]     The orifice  50  is worked by drilling in a partition wall  20   a  between the damper oil chamber  36  and the oil reservoir chamber  46  at an angle diagonally upward from the opening of the recessed portion  51 , before the valve body  20  is joined to the transmission case  2 . In order to make the drilling work possible, an axis L of the orifice  50  is disposed to pass through the opening of the recessed portion  51 .  
         [0040]      FIG. 4  shows a normal mounting posture of the valve body  20  onto the transmission case  2 . Namely, the valve body  20  is mounted on the inclined top surface  2   a  of the transmission case  2  so that a ceiling surface of the oil reservoir chamber  49  is located above the orifice  50 . Such a mounting posture of the valve body  20  is preferable, because the orifice  50 , which is diagonally worked by drilling from the side of the open surface of the recessed portion  51 , is brought into a substantially horizontal state, and air bubbles can be smoothly discharged to the oil reservoir chamber  49  from the damper oil chamber  36 .  
         [0041]     The transmission case  2  is provided with a drain oil hole  52  which opens the oil reservoir chamber  49  into the oil tank  46  to keep the oil reservoir chamber  49  under atmospheric pressure. In this case, the opening of the drain oil hole  52  to the oil reservoir chamber  49  is placed above the orifice  50  so that the oil, which moves into the oil reservoir chamber  49  from the orifice  50 , is discharged to the drain passage  52  after the oil is stored sufficiently in the oil reservoir chamber  49  to submerge the orifice  50  in the oil.  
         [0042]     Next, an operation of the first embodiment will be explained.  
         [0043]     When the linear solenoid unit S is not energized, the spool  22  is located at a rightward movement limit position (retreat limit) by the biasing force of the return spring  23  as shown in  FIG. 3 , so that the spool  22  provides communication between the supply port  37  and the output port  38 , and provides blockage between the output port  38  and the drain port  39 . Therefore, when the hydraulic pump  42  is driven by the engine to generate hydraulic pressure, the hydraulic pressure is transmitted to the reaction force oil chamber  35  through the supply oil passage  41 , the supply port  37  and the feed back oil passage  48 . Then, in this reaction force oil chamber  35 , the leftward thrust force with the magnitude, which is obtained by multiplying the hydraulic pressure by the area difference of the opposing end surfaces between the second land portion  25   2  with the small diameter and the third land portion  25   3  with the large diameter of the spool  22 , acts on the spool  22 , as the reaction force to resist the biasing force of the return spring  23 .  
         [0044]     On the other hand, when the coil  10  of the linear solenoid unit S is energized, the electromagnetic force corresponding to the current value acts on the spool  22  via the output rod  14  as the leftward thrust force. As a result, the spool  22  moves to a position where the three forces, that is, the leftward thrust force generated in the reaction force oil chamber  35 , the leftward thrust force by the electromagnetic force and the rightward thrust force by the return sprint  23  are balanced, and controls the opening degree of the supply port  37 . Namely, when the combined leftward thrust force is larger than the rightward thrust force, the spool  22  advances leftward, so that the first land portion  25   1  provides blockage between the supply port  37  and the output port  38 , and the second land portion  25   2  provides communication between the output port  38  and the drain port  39 . Therefore, the hydraulic pressure of the output port  38  decreases. On the other hand, when the rightward thrust force becomes larger than the leftward composite thrust force, the spool  22  advances rightward, so that the second land portion  25   2  provides blockage between the output port  38  and the drain port  39 , and the first land portion  25   1  provides communication between the supply port  37  and the output port  38 . Therefore, the hydraulic pressure of the output port  38  increases. Since the opening degree of the output port  38  is controlled as described above, the hydraulic pressure corresponding to the value of the current applied to the coil  10  is taken out of the output port  38 , and supplied to the hydraulic pressure operating unit  44 .  
         [0045]     The hydraulic control valve  1  is a normally open type in which the supply port  37  is normally opened, and therefore, when the hydraulic pump  42  operates, the generated hydraulic pressure is instantly supplied to the reaction force oil chamber  35  as described above. In addition, the reaction force oil chamber  35  and the damper oil chamber  36  adjacent thereto communicate with each other via the slide gap g between the third land portion  25   3  and the fourth annular land portion  31   4 . Therefore, when the hydraulic pressure is supplied to the reaction force oil chamber  35 , oil immediately leaks from the reaction force oil chamber  35  to the damper oil chamber  36 , to fill the damper oil chamber  36  with oil. Accordingly, the damper oil chamber  36  can function normally without a delay from the early stage of the operation of the hydraulic control valve  1 . Namely, when the spool  22  vibrates, the vibration of the spool  22  can be suppressed by the throttle resistance of the orifice  50 , which occurs when the oil of the damper oil chamber  36  moves to and from the orifice  50  following the vibration of the spool  22 . Therefore, the pulsation of the output hydraulic pressure due to the vibration of the spool  22  is prevented to ensure a stable operation state of the hydraulic operating unit  44 .  
         [0046]     When the damper oil chamber  36  is filled with the leak oil from the reaction force oil chamber  35 , the surplus oil is discharged from the orifice  50  into the adjacent oil reservoir chamber  49  to be stored therein. When the oil level of the oil reservoir chamber  49  reaches a predetermined level at which the orifice  50  is submerged under the oil level, the oil overflows through the drain oil hole  52  to return to the oil tank  46 .  
         [0047]     As described above, the leak oil is positively supplied to the damper oil chamber  36  from the reaction force oil chamber  35 , and the orifice  50  is submerged in the oil which is discharged into and stored in the oil reservoir chamber  49  through the orifice  50 . Therefore, the damper oil chamber  36  is always reliably filled with oil, and the favorable vibration suppressing function of the damper oil chamber  36  can be obtained. Accordingly, it is not necessary to submerge the damper oil chamber  36  in the oil of the oil tank as in the prior art, thereby eliminating the restriction on the arrangement of the normally open hydraulic control valve to enhance general versatility.  
         [0048]     Since the orifice  50  is opened to the uppermost portion of the damper oil chamber  36 , the air bubbles generating in the damper oil chamber  36  and the oil can be quickly discharged to the oil reservoir chamber  49  through the orifice  50 , and thus better vibration suppressing function of the damper oil chamber  36  can be obtained.  
         [0049]     Incidentally, the axis L of the orifice  50  is disposed to pass through the downward opening of the recessed portion  51  of the valve body  20 , and therefore the orifice  50  can be worked by drilling in the partition wall  20   a  between the damper oil chamber  36  and the oil reservoir chamber  46  without interference by the outer wall of the oil reservoir chamber  46 . Since a castoff hole is not required, a closing plug for closing the castoff hole as in the prior art is not required after the drilling work, thus contributing to reduction in the cost.  
         [0050]     Meanwhile, the outer peripheral surface of the third land portion  25   3  is constructed by a cylindrical slide surface  25   3a  which fitted to the fourth annular land portion  31   4 , and the taper surface  25   3b  which becomes smaller in diameter toward the reaction force oil chamber  35  from the cylindrical slide surface  25   3a , as mentioned above. Therefore, even when the third land portion  25   3  receives side thrust and is moved to one side of the fourth annular land portion  31   4  by leak oil passing through the slide gap g between the third land portion  25   3  and the fourth annular land portion  31   4 , one side portion of the cylindrical slide surface  25   3a  abuts to the inner peripheral surface of the fourth annular land portion  31   4 , but the taper surface  25   3b  does not contact the fourth annular land portion  31   4  over the entire circumference. Accordingly, the hydraulic pressure of the reaction force oil chamber  35  acts on the entire peripheral surface of the taper surface  25   3b  to give an aligning force to the third land portion  25   3 , thereby ensuring smooth slide of the third land portion  25   3  with respect to the fourth annular land portion  31   4 .  
         [0051]     Next, a second embodiment of the present invention shown in  FIG. 5  will be explained.  
         [0052]     In the second embodiment, the oil reservoir chamber  49  is constructed to be compact, and a drain pipe  53 , which rises at the drain oil hole  52  and extends to a position above the orifice  50 , is mounted in the transmission case  2 . The other parts of construction are the same as in the previous embodiment, and therefore the parts corresponding to the previous embodiment are given the identical reference numerals and characters in  FIG. 5 , and the explanation of them will be omitted.  
         [0053]     According to the second embodiment, the oil stored in the oil reservoir chamber  49  does not overflow unless the oil level reaches the upper end of the drain pipe  53 , which is located at the position above the orifice  50 . Therefore, the orifice  50  can be submerged in the oil of the oil reservoir chamber  49 , though the oil reservoir chamber  49  is constructed to be compact.  
         [0054]     Next, a third embodiment of the present invention shown in  FIG. 6  will be explained.  
         [0055]     In the third embodiment, the outer peripheral surface of the third land portion  25   3  is constructed by connecting a reduced diameter cylindrical surface  25   3c , which is in place of the taper surface  25   3b  of the first embodiment, to the cylindrical slide surface  25   3a  via an annular step portion. Since the other parts of construction are the same as in the first embodiment, the parts corresponding to the first embodiment are given the identical reference numerals and characters in  FIG. 6 , and the explanation of them will be omitted.  
         [0056]     Also in the third embodiment, even when the third land portion  25   3  receives side thrust for some reason and is moved to one side of the fourth annular land portion  31   4 , one side portion of the cylindrical slide surface  25   3a  abuts to the inner peripheral surface of the fourth annular land portion  31   4 , but the reduced diameter cylindrical surface  25   3c  does not contact the fourth annular land portion  31   4  over the entire circumference. Accordingly, the hydraulic pressure of the reaction force oil chamber  35  acts on the entire peripheral surface of the reduced diameter cylindrical surface  25   3c  to give the aligning force to the third land portion  25   3 , thus ensuring smooth slide of the third land portion  25   3  with respect to the fourth annular land portion  31   4 . The reduced diameter cylindrical surface  25   3c  has an advantage in being easier to work than the taper surface  25   3b  of the first embodiment.  
         [0057]     Finally, a fourth embodiment of the present invention shown in  FIG. 7  will be explained.  
         [0058]     In the fourth embodiment, while forming the cylindrical slide surface  25   1a  fitted to the first annular land portion  31   1  and a cylindrical slide surface  25   1a , which is fitted to and separated from the second annular land portion  31   2 , a taper surface  25   1b  which becomes smaller in diameter toward the cylindrical slide surface  25   1a , is formed on the outer peripheral surface of the first land portion  25   1 . Also in the second land portion  25   2 , a taper surface  25   2b , which becomes smaller in diameter toward the reaction force oil chamber  35 , is formed at the end portion at the side of the reaction force oil chamber  35 , while forming the cylindrical slide surface  25   2a , which is fitted to the second and the third annular land portions  25   2  and  25   3 . Since the other parts of construction are the same as that in the first embodiment, the parts corresponding to the second embodiment are given the identical reference numerals and characters in  FIG. 7 , and the explanation of them will be omitted. In short, in the fourth embodiment, the taper surfaces  25   1b  to  25   3b  are formed on the outer peripheral surfaces of the first to the third land portion  25   1  to  25   3 .  
         [0059]     Accordingly, the hydraulic pressure introduced into the supply oil chamber  32  from the supply port  37  acts on the taper surface  25   1b  of the first land portion  25   1 , and therefore the aligning force acts on the first land portion  25   1 . The hydraulic pressure of the reaction force oil chamber  35  acts on the taper surface  25   2b  of the second land portion  25   2  as in the taper surface  25   3b  of the third land portion  25   3 , and therefore the aligning force also acts on the second land portion  25   2 . Thus, the aligning force is applied to all the land portions  25   1  to  25   3 , thereby ensuring a smooth slide state of the spool  22 .  
         [0060]     The present invention is not limited to the above-described embodiments and modifications, and various design changes may be made without departing from the subject matter of the present invention. For example, the present invention is applicable to a normally closed hydraulic control valve. Oil can be supplied to the damper oil chamber  49  also from the drain port  36 .

Technology Classification (CPC): 5