The present invention relates to synchronizers, especially synchronizers used in dual clutch automatic transmissions (DCT) such as shown in U.S. Pat. No. 6,012,561, Reed Jr. et al., the disclosure of which is incorporated by reference herein.
The conventional gear selection system used for most if not all of DCTs in production today is synchronizers. The synchronizers are engaged and disengaged through a hydraulic actuation valve via a standard manual shift fork and rail system. One of the disadvantages to this system is the differential speed between the shift fork and the sleeve of the synchronizer. The above noted interface requires sufficient lubrication to prevent wear. Another issue with DCT is that high clutch drag can sometime cause block out of the engagement of the synchronizer or prevent a blocker ring from indexing.
The present invention provides a hydraulic actuated synchronizer that eliminates the shift fork in a manner that is an alternative to those revealed prior.
Other features of the invention will become more apparent to those skilled in the art as the invention is further revealed in the accompanying drawings and Detailed Description of the Invention.
Referring to
Press fitted on the hub 10 is a cylinder 28. Press fitted on the hub 10 against hub shoulders 30 are two end plates 32. A radial extreme end of the end plates 32 mount a ring sealing member 34. Slideably sealably mounted on an outer diameter of the hub 10 is a dual piston 36. The piston 36 has a divider plate 38 that mounts on its extreme end a ring sealing member 40 forming connected pistons with a common body. The piston 36 forms variable control volumes 42 and 120 with the hub 10. The control volume 42 intersects the second passage 24. The piston 36 has axial movement along an axis 17 in response to the fluid pressure within the control volume 42.
The synchronizer 7 has two brackets 46. The bracket 46 has spline teeth 48 that engage hub spline teeth 56 causing the bracket 46 to rotate with the hub 10. The bracket 46 has a shoulder 52 that abuts an axial end 54 of the piston 36 to allow the bracket 46 to be moved along the axis 17 by the piston 36. The bracket 46 has gear teeth 50.
The synchronizer 7 has a friction member provided by a synchronizer cone 58. The cone 58 has a friction surface 60 that is angled with respect to the axis 17. As shown in
The bracket 48 has a series of pin holes 70. Extending through each pinhole 70 is a spring pin 72. The pin 72 has shoulders 74 that abut against an inboard surface 76 of the brackets 46 to limit the position of the brackets 46 relative to the pin 72. The pin 72 at its opposite end has a connected nail head 78. The nail head 78 captures between itself and the bracket 46 a coil return coiled spring 80 to bias the bracket 46 and the piston 36 to a neutral non-engaged position.
A second drive is provided by a gear 82 rotatably connected on the shaft 12 by a needle bearing 84. In a similar manner, a third drive is provided by a gear 86 mounted on a needle bearing 88. The gears 82, 86, and the hub 10 are axially fixed on the shaft 12. The gear 82 has a side face 90 and a gear tooth face 92. A second drive lubrication passage 94 connects the side face 90 with the gear face 92. Interference or press fitted on the gear 82 is a dog leg 96. The dog leg 96 has a friction surface 98 and gear teeth 100.
In a manner similar to that described for a the gear 82, gear 86 has a side face 102, a third drive lubricating passage 104, gear face 106 and a dog leg 108 a with friction surface 110 and gear teeth 112.
In operation, the gears 82 and 86 mesh with other gears on a different shaft (not shown) of a transmission. Typically, the gears 82 and 86 provide the transmission with two gear ratios that are two gear shift ratios apart. For example, gear 86 can be the second gear and gear 82 can be the fourth gear. If the transmission is in fifth gear, the synchronizer 7 is in the neutral position as shown at the top of
The shaft 12 also has a shaft lubrication supply passage 114 that intersects with the first fluid passage 22. The shaft lubrication supply passage 114 is fluidly connected with a hub lubrication passage 116. Pressurize oil (transmission fluid) flowing through the hub lubrication passage 116 lubricates the interface between the friction surfaces 60 and 98 as well as the interface between the gear teeth 50 and 100. The oil from the hub lubrication passage 116 will eventually pass through the second drive lubrication passage 94 before lubricating the gear tooth face 92.
If the transmission down shifts to third gear, fluid pressure within the first fluid passage 22 will be released causing a depressurization of the first control volume 42. Return springs 80 will pushed the bracket 46 leftward causing the teeth 50 and 100 to disengage. Further leftward movement of the bracket 46 causes the friction surfaces 60 and 98 to disengage.
When the control volume 42 is pressurized and the bracket 46 is moved rightward, return springs 80 on both sides of the hub 10 both are compressed. The return springs 80 on the right hand side of the hub will be compressed a greatest amount. The return springs 80 on both sides of the hub 10 will contribute to the return of the pin 72 to the neutral position increasing the reaction time of the synchronizer 7 to the released or neutral position. The spring constant of the return springs 80 can vary due to manufacturing tolerances. If the springs 80 are not equally matched in their spring constant across the hub 10, the springs 80 can cause the synchronizer 7 to have a tendency to self-engage. To prevent the above noted tendency pin shoulders 74 are provided which limit the axial position of the brackets 46 on the pins 72.
In an alternate preferred embodiment synchronizer 127 shown in
To place the transmission into the second gear, the control volume 120 is pressurized via a separate fluid passage 122 (hereinafter referred to as the third fluid passage) and a fourth fluid passage 124. The operation for engagement of the second gear 86 to the shaft 12 is substantially identical to that described for engagement of the gear 82.
Referring to
In operation, a second passage 170 is pressurized to pressurize the control volume provided by the groove 144. The piston 146 is pushed rightward causing the nail head 78 to go against the cone flange 62. The friction surfaces 60, 98 engage as previously described. When the speed the gear 82 has been synchronized the gear teeth 158 mesh with the gear teeth 100. To activate the gear 86, the opposite piston 146 is activated in a similar manner.
While preferred embodiments of the present invention have been disclosed, it is to be understood it has been described by way of example only, and various modifications can be made without departing from the spirit and scope of the invention as it is encompassed in the following claims.
This application claims the benefit of U.S. Provisional Application No. 60/765,402 filed Feb. 3, 2006.
Number | Name | Date | Kind |
---|---|---|---|
3739890 | Nolli | Jun 1973 | A |
3921469 | Richards | Nov 1975 | A |
4131185 | Schall | Dec 1978 | A |
5377800 | Sperduti et al. | Jan 1995 | A |
5560461 | Loeffler | Oct 1996 | A |
5845754 | Weilant | Dec 1998 | A |
6012561 | Reed, Jr. et al. | Jan 2000 | A |
6588562 | Fernandez | Jul 2003 | B2 |
6647816 | Vukovich et al. | Nov 2003 | B1 |
6826974 | Kobayashi | Dec 2004 | B2 |
20040055844 | Ebenhoch et al. | Mar 2004 | A1 |
20060049018 | Legner | Mar 2006 | A1 |
Number | Date | Country | |
---|---|---|---|
20070181397 A1 | Aug 2007 | US |
Number | Date | Country | |
---|---|---|---|
60765402 | Feb 2006 | US |