Abstract:
The present invention relates to a manual valve of an automatic transmission, having a groove formed at an exterior surface thereof so as to reduce shock and to improve shift feel by allowing oil to flow through the groove when releasing hydraulic pressure. An exemplary manual valve of an automatic transmission includes a valve body and a valve spool slidably provided in the valve body. The valve body includes a spool receiving part, a first port, a second port, and a third port. The valve spool includes an underdrive land assembly and a reverse land assembly, wherein at least one of the underdrive land assembly and the reverse land assembly has a groove formed on an exterior circumference thereof along a sliding direction of the valve spool such that oil flows therethrough when hydraulic pressure is released.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims priority to and the benefit of Korean Patent Application No. 10-2004-0108234 filed in the Korean Intellectual Property Office on Dec. 17, 2004, Korean Patent Application No. 10-2004-0111358 filed in the Korean Intellectual Property Office on Dec. 23, 2004, Korean Patent Application No. 10-2005-0123552 filed in the Korean Intellectual Property Office on Dec. 15, 2005, the entire contents of which are incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     (a) Field of the Invention  
         [0003]     The present invention relates to a manual valve of an automatic transmission. More particularly, the present invention relates to a manual valve of an automatic transmission having a groove formed at an exterior surface thereof so as to reduce shock and to improve shift feel by allowing oil to flow through the groove when releasing hydraulic pressure.  
         [0004]     (b) Description of the Related Art  
         [0005]     In a typical automatic transmission of a vehicle, hydraulic pressure applied to a U/D (underdrive) clutch should be released so as to change a shift range from a D range to an N range, and hydraulic pressure applied to a reverse clutch should be released so as to shift a shift range from an R range to an N range. Generally, releasing of the hydraulic pressure applied to the underdrive clutch and the reverse clutch is performed by using an orifice and a manual valve.  
         [0006]     However, when the hydraulic pressure applied to the underdrive clutch or reverse clutch is abruptly released, a shock occurs and shift feel is problematically deteriorated.  
         [0007]     Therefore, a method for tuning a size of the orifice is used so as to solve the above-mentioned problems, and to improve the shift feel when changing the shift range from D range to N range or from R range to N range.  
         [0008]     However, if a size of the orifice is reduced so as to prevent immediate release of hydraulic pressure, the inflow speed of oil when applying hydraulic pressure to the U/D clutch or reverse clutch problematically becomes slower.  
         [0009]     In addition, if the size of the orifice is reduced, a viscosity change of oil (ATF) according to a change of temperature significantly affects the shift feel.  
         [0010]     The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.  
       SUMMARY OF THE INVENTION  
       [0011]     The present invention has been made in an effort to provide a manual valve of an automatic transmission having advantages of reducing shock and improving shift feel by allowing oil to flow through the groove when releasing hydraulic pressure.  
         [0012]     An exemplary manual valve of an automatic transmission according to an embodiment of the present invention includes a valve body and a valve spool slidably provided in the valve body. The valve body includes a spool receiving part for receiving the valve spool, a first port connecting the spool receiving part with an underdrive clutch, a second port connecting the spool receiving part with a reverse clutch, and a third port connecting the spool receiving part with a pump. The valve spool includes an underdrive land assembly for selectively opening/closing the first port, and a reverse land assembly for selectively opening/closing the second port, wherein at least one of the underdrive land assembly and the reverse land assembly has a groove formed on an exterior circumference thereof along a sliding direction of the valve spool such that oil flows therethrough when hydraulic pressure is released.  
         [0013]     The underdrive land assembly may include a first land and a second land protruded at both end thereof, a plane part formed between the first land and the second land, and a groove formed on a exterior circumference thereof along a sliding direction of the valve spool. The spool receiving part has a larger diameter at a position where the first port is formed, the first port is disposed between the first land and the second land when in the N (neutral) range, and oil flows from the first port to the outside of the valve spool through the groove.  
         [0014]     A penetration hole may be formed at the plane part.  
         [0015]     A reverse land assembly may include a third land and a fourth land protruded at respective ends thereof, a plane part formed between the third land and the fourth land, and a groove formed on an exterior circumference thereof along a sliding direction of the valve spool, wherein the spool receiving part has a larger diameter at a position where the second port is formed, the second port is disposed between the third land and the fourth land when in the N (neutral) range, and oil flows from the second port to the outside of the valve spool through the groove.  
         [0016]     A penetration hole may be formed at the plane part. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]      FIG. 1  is a perspective view of a valve spool according to an exemplary embodiment of the present invention.  
         [0018]      FIG. 2  is a cross-sectional view of an underdrive land assembly according to an exemplary embodiment of the present invention.  
         [0019]      FIG. 3  is a cross-sectional view of a reverse land assembly according to an exemplary embodiment of the present invention.  
         [0020]      FIG. 4A  is a schematic view of a manual valve according to an exemplary embodiment of the present invention.  
         [0021]      FIG. 4B  is a schematic view of a manual valve according to an exemplary embodiment of the present invention.  
         [0022]      FIG. 5A  is a schematic view of a manual valve according to an exemplary embodiment of the present invention.  
         [0023]      FIG. 5B  is a schematic view of a manual valve according to an exemplary embodiment of the present invention.  
                                                10:   underdrive clutch    20:   reverse clutch           (U/D clutch)       (reverse clutch)        30:   pump   100:   valve spool       110:   underdrive land assembly   111:   first land       112:   second land   113:   plane part       114:   penetration hole   115:   groove       120:   reverse land assembly   121:   third land       122:   fourth land   123:   plane part       124:   penetration hole   125:   groove       130:   connector   140:   central shaft       200:   valve body   210:   first port       220:   second port   230:   third port       240:   spool receiving part                    
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0024]     An exemplary embodiment of the present invention will hereinafter be described in detail with reference to the accompanying drawings.  
         [0025]     A manual valve according to an exemplary embodiment of the present invention includes a valve body  200  and a valve spool  100 .  
         [0026]     Hereinafter, referring to  FIG. 1  to  FIG. 3 , a structure of the valve spool  100  according to an exemplary embodiment of the present invention will be described in detail.  
         [0027]     The valve spool  100  according to an exemplary embodiment of the present invention includes a central shaft  140 , an underdrive land assembly  110  formed at an end of the central shaft  140 , a connector  130  formed at the other end of the central shaft  140  and being connected with a shift lever, and a reverse land assembly  120  formed between the underdrive land assembly  110  and the connector  130 .  
         [0028]     The underdrive land assembly  110  includes a first land  111  and a second land  112  protruded to have cylindrical shapes at respective ends thereof, a plane part  113  formed to be flat, and a groove  115  formed along a sliding direction of the valve spool at a exterior circumference of the underdrive land assembly  110 .  
         [0029]     The underdrive land assembly  110  has a cylindrical body, and a part of an exterior circumference of the cylindrical body is processed to be flat so as to form the plane part  113 . The non-processed part still has a cylindrical shape at both ends of the plane part  113 , which become the first land  111  and the second land  112 .  
         [0030]     A penetration hole  114  is formed at the center of the plane part  113 .  
         [0031]     The groove  115  is formed at the exterior circumference of the underdrive land assembly  110 . One end of the groove  115  is blocked by the first land  111 , and the other end thereof is open toward the outside of the second land  112 .  
         [0032]     The reverse land assembly  120  includes a third land  121  and a fourth land  122  protruded to have cylindrical shapes at both ends thereof, a plane part  123  formed to be flat, and a groove  125  formed along a sliding direction of the valve spool at an exterior circumference of the reverse land assembly  120 .  
         [0033]     The reverse land assembly  120  has a cylindrical body, and a part of an exterior circumference of the cylindrical body is processed to be flat so as to form the plane part  123 . The non-processed part still has a cylindrical shape at both ends of the plane part  123 , which become the third land  121  and the fourth land  122 .  
         [0034]     A penetration hole  124  is formed at the center of the plane part  123 .  
         [0035]     The groove  125  is formed at the exterior circumference of the reverse land assembly  120 . One end of the groove  125  is blocked by the first land  121 , and the other end thereof is open toward the outside of the second land  122 .  
         [0036]     The connector  130  is connected to a shift lever not shown in the accompanying drawings such that it causes the valve spool  100  to slide in the valve body  200 .  
         [0037]     Hereinafter, referring to  FIG. 4A  to  FIG. 5B , the valve body  200  according to an exemplary embodiment of the present invention will be described in detail.  
         [0038]     The valve body  200  according to the present exemplary embodiment of the present invention includes a spool receiving part  240  wherein the valve spool  100  slides, a first port  210  connected with the underdrive clutch  10 , a second port  220  connected with the reverse clutch  20 , and a third port  230  connected with a pump  30 .  
         [0039]     The spool receiving part  240  is formed in the valve body  200  such that the valve spool  100  slides therewithin.  
         [0040]     The spool receiving part  240  has a cylindrical shape having a diameter that is virtually the same as external diameters of the first land  111  to the fourth land  122 . However, the diameter of the spool receiving part  240  becomes larger at positions where the first port  210  and the second port  220  are formed.  
         [0041]     Therefore, oil (ATF) does not flow between the interior circumference of the spool receiving part  240  and the exterior circumference of the first land  111  to the fourth land  122 , except at the. positions having larger diameters.  
         [0042]      FIG. 2  shows a schematic cross-sectional view of the underdrive land assembly  110  being received in the valve body  200 .  
         [0043]     The underdrive land assembly  110  is formed to have a cylindrical shape having an inner diameter d 2 , and has the groove  115  formed at an exterior circumference thereof. Reference numeral  140  indicates the central shaft, shown by a dotted line and having a diameter d 1  that is smaller than the diameter d 2  of the underdrive land assembly  110 .  
         [0044]     The spool receiving part  240  of the valve body  200  has an inner diameter d 2  that is virtually the same as the diameter of the underdrive land assembly  110 . However, the spool receiving part  240  of the valve body  200  has an inner diameter d 3  where the first port  210  is formed.  
         [0045]      FIG. 3  shows a schematic cross-sectional view of the reverse land assembly  120  being received in the valve body  200 .  
         [0046]     The reverse land assembly  120  is formed to have a cylindrical shape having an inner diameter d 2 , and has a groove  125  formed at an exterior circumference thereof. Reference numeral  140  indicates the central shaft, shown by a dotted line and having a diameter d 1  that is smaller than the diameter d 2  of the reverse land assembly  120 .  
         [0047]     The spool receiving part  240  of the valve body  200  has an inner diameter d 2  that is virtually the same as the diameter of the reverse land assembly  120 . However, the spool receiving part  240  of the valve body  200  has an inner diameter d 3  where the first port  210  is formed.  
         [0048]     Hereinafter, referring to  FIG. 4A  to  FIG. 4B , a process for operating a manual valve according to an exemplary embodiment of the present invention, when changing a shift range between D range and N range will be described in detail.  
         [0049]      FIG. 4A  shows a flow of oil where oil flowing into the spool receiving part  240  through the third port  230  from the pump  30  flows into the U/D clutch  10  through the first port  210 .  
         [0050]     When a driver moves a shift lever to the D range, the valve spool  100  moves such that the first land  111  is disposed outside the first port  210  (referring to  FIG. 4A , left side of the first port). Then, the third port  230  and the first port  210  communicate with each other, and hydraulic pressure is applied to the underdrive clutch  10  by operation of the pump  30 . At this time, the oil is blocked by the first land  111  and the third land  121  and exists in a space between the first land  111  and the third land  121 , in the spool receiving part  240 .  
         [0051]     That is, since the first land  111  and the third land  121  have the diameter d 2  that is virtually the same as a diameter of the spool receiving part  240 , a flow of oil to the outside of the first land  111  and the third land  121  is prevented.  
         [0052]     When the driver moves the shift lever from the D range to the N range, the valve spool  100  moves to the right, as shown in  FIG. 4B , and the first port  210  is disposed between the first land  111  and the second land  112 .  
         [0053]     At this time, since the diameter d 3  of the spool receiving part  240  where the first port  210  is larger than the diameter d 2  of the underdrive land assembly  110 , oil flows into the groove  115 . Then, the oil flowing into the groove  115  flows out of the second land  112  through an opening of the groove.  
         [0054]     At this time, some of the oil from the underdrive clutch  10  flows to the plane part  113  through the first port  210 . The oil flowing to the plane part  113  is blocked by the first land  111  and the second land  122 , and flows into the opposite plane part through the penetration hole  114 . Therefore, a hydraulic pressure of both plane parts can be balanced.  
         [0055]     According to the above-described operation of the manual valve whew shifting between D range and N range, since oil rapidly flows into the underdrive clutch  10 , and slowly flows out of the underdrive clutch  10 , shock does not occur and shift feel is improved to be smoother.  
         [0056]     Hereinafter, referring to  FIG. 5A  to  FIG. 5B , a process for operating a manual valve according to an exemplary embodiment of the present invention, when changing a shift range between R range and N range, will be described in detail.  
         [0057]      FIG. 5A  shows a flow of oil where oil flowing into the spool receiving part  240  through the third port  230  from the pump  30  flows into the reverse clutch  20  through the second port  220 .  
         [0058]     When the driver moves the shift lever to the R range, the valve spool  100  moves such that the third land  121  is disposed outside the second port  220  (referring to  FIG. 5A , right side of the first port). Then, the third port  230  and the second port  220  communicate with each other, and hydraulic pressure is applied to the reverse clutch  20  by operation of the pump  30 . At this time, the oil is blocked by the first land  111  and the third land  121  and exists in a space between the first land  111  and the third land  121 , in the spool receiving part  240 .  
         [0059]     That is, since the first land  111  and the third land  121  have a diameter d 2  that is virtually the same as a diameter of the spool receiving part  240 , a flow of oil to the outside of the first land  111  and the third land  121  is prevented.  
         [0060]     When the driver moves the shift lever from the R range to the N range, the valve spool  100  move to the left, as shown in  FIG. 5B , and the second port  220  is disposed between the third land  121  and the fourth land  122 .  
         [0061]     At this time, since the diameter d 3  of the spool receiving part  240  where the second port  220  is larger than the diameter d 2  of the reverse land assembly  120 , oil flows into the groove  125 . Then, the oil flowing into the groove  125  flows out of the fourth land  122  through an opening of the groove.  
         [0062]     At this time, some of the oil from the reverse clutch  20  flows to the plane part  123  through the second port  220 . The oil flowing to the plane part  123  is blocked by the third land  121  and the fourth land  122 , and flows into the opposite plane part through the penetration hole  124 . Therefore, hydraulic pressure of both plane parts can be balanced.  
         [0063]     According to the above-described operation of the manual valve when shifting between R range and N range, since oil rapidly flows into the reverse clutch  10 , and slowly flows out of the reverse clutch  10 , shock does not occur and shift feel is improved to be smoother.  
         [0064]     Therefore, by adjusting a size of the groove, appropriate shift feel can be achieved.  
         [0065]     According to the above-described present invention, when changing a shift range between D range and N range, or R range and N range, rapid releasing of hydraulic pressure is prevented. Therefore, shock is reduced, and shift feel is improved to be smoother.  
         [0066]     While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.