Abstract:
A manual valve which is used for an automatic transmission is designed to be shortened axially. 
     A port for reverse running and the ports for forward running are made on the same axial direction against ports for the port for line pressure application. 
     A spool has; a first oil chamber which connects the port for line pressure application and the ports for forward running, a second oil chamber which connects the port for reverse running and the port for line pressure application or a drain hole, and a drain path connecting the ports for forward running and the drain portion.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a manual valve which is shortened axially, and suitable for an automatic transmission for an automobile particularly to a F.F. (front engine, front drive) mounted small type car. 
     2. Description of the Prior Art 
     A manual valve in an automatic transmission has a spool comprising a cylindrical &#34;land&#34; portion and a circular &#34;groove&#34; portion, and ports for forward running and a port for reverse running which are located in the same axial direction along a port for line pressure application. 
     As shown in FIG. 12, a previously proposed manual valve V&#39; has an oil chamber 5&#39;a in a connecting area, so that the distance between a port R and a port D is shortened; however, a port P L  for a line pressure application is still located between the port for reverse running (R) and the ports for forward running (D, 3, 2 and 1). Due to the above, a certain length is necessary from the port for line pressure application P L  to both the port R for reverse running and ports D, 3, 2 and 1 for forward running particularly port 1, so that the case or valve body where each port is located becomes long axially, so that a large space is required. 
     In particular, recently due to the requirements of front-engine-front-drive and high efficiency, an automatic trnsmission has been required to be small sized and be a multiple-speed transmission. Under such circumstances, in such a small sized and multiple-speed transmission, a shortened manual valve is required because the installation space in a trans axle case is limited. 
     The present invention proposes to shorten the manual valve by setting the ports for forward running and the port for reverse running in the same axial direction from the port for line pressure application. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a manual valve which comprises: a port for reverse running and ports for forward running in the same axial direction from a port for line pressure application; a spool having a first oil chamber connecting the line pressure application port and each forward running port; a second oil chamber connecting the reverse running port and the line pressure application port, or a drain portion; and a drain path connecting each forward running port and the drain portion. 
     Based on the structure described above, when a vehicle runs forward, the spool will be positioned corresponding to one of the forward running ports of the manual valve, line pressure from the line pressure application port is applied to the ports corresponding to each forward speed through the first oil chamber. 
     When a vehicle runs in reverse, the spool is positioned corresponding to the reverse running port of the manual valve, and line pressure from the line pressure application port is applied to the reverse port through the second oil chamber. 
     As explained, the present invention shows that, in the manual valve, the ports for forward running and the ports for reverse running are positioned in the same axial direction from the port for line pressure application, so that the overall length, particularly the area where the ports are located, is shortened. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic cross sectional view of a manual valve according to the present invention; 
     FIG. 2 is an overall cross sectional view of the manual valve of FIG. 1; 
     FIG. 3 is a plan view of a trans axle case in which the manual valve of FIG. 2 is installed; 
     FIGS. 4-10 are schematic views showing the positions of the manual valve for various drive conditions; 
     FIG. 11 is a cross sectional view of another embodiment of the valve of the present invention; and 
     FIG. 12 is a cross sectional view of a previously proposed valve. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following is a description of an embodiment of a valve in accordance with the present invention. 
     A manual valve V installed in a trans axle case shown in FIG. 3 is used for a small and multiple speed automatic transmission particularly for use in a 5 forward speed automatic transmission and which an applicant of the present invention disclosed in Japanese patent applications 60-230809 and 60-230810, now Laid Open Applications Nos. 62-93545 and 62-93546 of Apr. 30, 1987. 
     In the trans axle case 11, the manual valve is installed transversely shown in FIG. 3 because the automatic transmission is quite small, so that C portion having other valves shown in FIG. 3, is not available for providing ports of the manual valve, and the center of the manual valve installed transversely has ports for forward and reverse, and a port for line pressure application P L . As shown in FIG. 2, the case 11 has a valve bore 11a, and in the bore 11a, a spool 5 is freely slidably inserted to provide a slide motion. Furthermore, one of the ends of the spool 5 is linked to a part 13 which is fixed to a shaft 12 so that spool 5 can be moved axially and cannot rotate around its axis, and the shaft 12 is linked to a shift lever near a driver&#39;s seat. 
     As shown in FIG. 1, the case 11 has ports D, 3, 2 and 1 corresponding to the operating positions of the shift lever &#34;D-3-2-1&#34;, has a port R corresponding to a reverse operating position R of the shift lever, and a port for line pressure application P L . In the edge of the valve bore 11a, a drain portion 6 is provided. The forward ports D, 3, 2 and 1 are located on one side in the valve bore 11a, and the reverse port R and the port P L  are located on the opposite side of the valve bore 11a and the spool 5; each forward port and the reverse port are located on the same axial side of the port P L  for line pressure application. 
     The forward port 1 and the reverse port R which are at the farthest port from the port P L  are in the same transverse plane of the valve bore 11a. 
     The spool 5 has step-like projections (hereinafter called &#34;land portions&#34;) namely a first land portion 5e and a second land portion 5f, the spool having a reduced diameter portion therebetween defining an oil chamber 5a for forward operation having different patterns of oil flowing on both sides of the valve bore 11a. Third land portion 5g is spaced along the spool from the second land portion 5f and the spool has a circular segmental cross-sectional shape reduced diameter portion extending from the land portion 5g in axial direction to the land portion 5f to define between the third land portion 5g and the second land portion 5f an oil chamber 5b for reverse operation; on the opposite side of the land portion 5g from chamber 5b is a drain chamber 5c formed by a further circular segmental cross-sectional shape reduced diameter portion. The length l 1  of the oil chamber 5b is equal to that from the port P L  (left side) to the port R (right side), and also that from the port P L  (right side) to the drain portion 6 (the edge of the case 11). The length l 1  is longer than that of l 2  from the left side of port D to the right side of the port 1. Furthermore, the length &#34;a&#34; which is a sum of off-sets, a covering area of the ports, of land portion 5f and thickness of 5f, extends from the right side of the port P L  to the left side of the port D. 
     As this embodiment has structure described above, in the parking position shown in FIG. 4, the port P L  opens into the oil chamber 5b (for reverse), which is not connected to any other ports; the reverse port R and the forward ports (D, 3, 2 and 1) are connected to the drain portion 6, the forward ports D, 3 and 2 opening into drain chamber 5c. 
     In the reverse position shown in FIG. 5, the forward ports are still connected to the drain portion 6 through drain chamber 5c, the port P L  is connected to the reverse port R through the chamber 5b. 
     In the neutral position shown in FIG. 6, the port P L  for line pressure application opens into the oil chamber 5a (for forward), which is not connected to any other ports, the reverse port R is connected to the drain portion 6 through the oil chamber 5b (for reverse) and the forward ports (D, 3, 2 and 1) are connected to the drain portion 6 through the drain chamber 5c. 
     In the D position shown in FIG. 7, the port P L  is connected to the port D through chamber 5a, and the reverse port R and the forward ports (1, 2 and 3) are connected to the drain portion 6. 
     In the 3 position shown in FIG. 8, the reverse port R and the forward ports (1 and 2) are connected to the drain portion 6, and the port P L  is connected to the ports D and 3 through the chamber 5a. 
     In the 2 position shown in FIG. 9, the reverse port R and the forward port 1 are connected to the drain portion 6, and the port P L  is connected to the ports D, 3, 2 and 1 through the chamber 5a. 
     In the 1 position shown in FIG. 10, the reverse port R is connected to the drain portion 6, and the port P L  is connected to the forward ports D, 3, 2, and 1 through the chamber 5a. 
     A second embodiment is explained below in connection with FIG. 11. 
     In this embodiment, the port P L  for line pressure application and reverse port R, and the forward ports (D, 3, 2 and 1) have similar relative positions as the corresponding ports in FIGS. 1-10, and the reverse port R and the forward ports (D, 3, 2 and 1) are located on the same side of the port for line pressure application P L . However, ports D, 1, 2 and 3 are shifted in the axial direction of bore 11a toward port P L  so that the port P L  and the forward port D are in the same transverse plane. The spool 5 has the oil chamber 5a (for forward), the oil chamber 5c (for reverse) and drain chamber 5c. The length of the chamber 5b, l l , and the length between the port P L  and the port R and the drain portion 6, and the overall length of the forward ports l 2  ; the relation (l 1  &gt;l 2  2) is the same as in the previous embodiment; however, the off-set of &#34;land portion&#34; 5f whose length of the port P L  side is longer than that of the forward port D, and the length &#34;a&#34;, i.e., the off-set amount minus the thickness of 5f is the same as the width of the port P L  and the port D; these are different from the previous embodiment. 
     FEASIBILITY FOR THE RELATED INDUSTRIES 
     A manual valve installed in an automatic transmission related to the present invention can be used for automobiles, trucks, small sized cars, special purpose vehicles and cars in general. And the most suitable application is for an automatic transmission which is small sized and has a five-speed multiple transmission with a front-engine-front-drive system.