초록 ▼

A transmission control system is provided for use with a transmission assembly having a torque converter which couples a power input member with a transmission speed ratio section. A lock-up clutch is provided to selectively bypass the torque converter and couple the input member directly with the t

A transmission control system is provided for use with a transmission assembly having a torque converter which couples a power input member with a transmission speed ratio section. A lock-up clutch is provided to selectively bypass the torque converter and couple the input member directly with the transmission speed ratio section. Some systems provide converter lock-up and lower transmission control pressure resposive to positioning of the transmission speed selector valve while others require additional complicated controls to operate the lock-up clutch of the converter and reduce transmission control pressure relative to the vacuum level of the prime mover. In the subject arrangement, a single valve (112) that is responsive to the output speed of the transmission (10) simultaneously actuates the lock-up clutch (32) of the torque converter (14) and lowers the operating pressure level of a dual stage pressure relief valve (72) by directing a fluid pressure signal to an actuating chamber (106) of the dual stage pressure relief valve (72). This arrangement ensures that the output speed of the transmission is operated at a sufficient low torque level before the lock-up clutch is actuated and furthermore does not require numerous complicated controls to lower the transmission control operating pressure and actuate the lock-up clutch.

대표청구항 ▼

1. A transmission control system (12) adapted for use with a transmission assembly (10) having a torque converter (14) for coupling a power input member (22) with a transmission speed ratio section (16), a hydraulically actuated lock-up clutch (32) arranged to selectively bypass the torque converter

1. A transmission control system (12) adapted for use with a transmission assembly (10) having a torque converter (14) for coupling a power input member (22) with a transmission speed ratio section (16), a hydraulically actuated lock-up clutch (32) arranged to selectively bypass the torque converter (14) and effectively couple the input member (22) directly with the transmission speed ratio section (16), and a source (47) of pressurized control fluid for supplying fluid to the torque converter (14) and the transmission speed ratio section (16), the system comprising: first valve means (60) for selectively directing pressurized fluid from the source (47) to actuate the lock-up clutch (32); second valve means (70) for controlling the pressure level between the source (47) and the transmission speed ratio section (16) to two distinct pressure levels; and single valve means (112) adapted to simultaneously actuate the first and second valve means (60,70) to respectively actuate the lock-up clutch (32) and reduce the pressure level of the source (47) to the lower of the two distinct pressures in response to the output speed of the transmission (10) exceeding a predetermined speed. 2. The control system (12), as set forth in claim 1, wherein the first valve means (60) includes a two position valve (62) connected between the lock-up clutch (32) and the source (47) and movable between a first position at which communication between the source (47) and the lock-up clutch (32) is blocked and a second position at which the source (47) is in fluid communication with the lock-up clutch (32), said two position valve (62) being moved to the second position in response to actuation of said single valve (112). 3. The control system (12), as set forth in claim 2, wherein the two position valve (62) has a pilot actuation chamber (68) and a conduit (118) connecting the actuation chamber (68) to the single valve (112). 4. The control system (12), as set forth in claim 3, wherein the second valve means (70) includes a dual stage pressure relief valve (72) connected to said source (47) of pressurized control fluid and adapted to establish the two distinct pressure levels. 5. The control system (12), as set forth in claim 4, wherein said dual stage pressure relief valve (72) is conditioned to establish the lower of the two distinct pressure levels in response to actuation of the single valve (112). 6. The control system (12), as set forth in claim 5, wherein the two stage pressure relief valve (72) includes an actuation chamber (106) and the second valve means (70) further includes a pressure responsive selector valve (108) connected between the source (47) and said actuation chamber (106), said selector valve (108) being movable between a first position at which fluid communication from the source (47) is blocked from the actuation chamber (106) and a second position at which the fluid communication is open, said selector valve (108) being movable to the second position in response to actuation of the single valve (112). 7. The control system (12), as set forth in claim 6, wherein the two stage pressure relief valve (72) includes a housing (82) defining a bore (84) therein, an inlet port (86), an outlet port (88) and a signal port (90) located in the housing (82) and intersecting the bore (84); and a spool (92) slideably located in the bore (84) and adapted to controllably interconnect the inlet port (86) and the outlet port (88) in response to the pressure level in the inlet port (86) exceeding the higher of the two distinct pressure levels and the source (47) being blocked from the actuation chamber (106). 8. The control system (12), as set forth in claim 7, wherein said spool (92) defines an annular groove (98) located between a pair of lands (94,96), an axial bore (100) in one of said lands (94,96), one end of which opens to one end of the spool, and a transverse passage (102) connecting the other end of the axial bore (100) to the annular groove (98); and including a reaction slug (104) slideably disposed in said axial bore (100), said actuation chamber (106) being defined between one end of the bore (84) and the one end of the spool (92). 9. The control system (12), as set forth in claim 8, wherein the two stage pressure relief valve (72) includes a spring (93), the spool (92) is movable between a first position at which communication between the inlet port (86) and the outlet port (88) is blocked and a second position at which the communication is open, said spool being movable to the second position in response to the pressure level in the inlet port (86) exceeding said higher pressure level and said source (47) being blocked from the actuation chamber (106), and biased to the first position by the spring (93). 10. The control system (12), as set forth in claim 9, wherein said lower pressure level is established in response to a pressurized fluid signal fluid being communicated to said actuation chamber (106). 11. The control system (12), as set forth in claim 10, wherein the single valve means (112) is a solenoid actuated valve movable between a non-actuated position at which the fluid from said source (47) is blocked from said two position valve (62) and said selector valve (108) and an actuated position at which the fluid from said source (47) is free to communicate with said two position valve (62) and said selector valve (108). 12. The control system (12), as set forth in claim 1, wherein the source (47) of pressurized control fluid includes first and second pumps (48,134). 13. The control system (12), as set forth in claim 12, wherein the first valve means (60) includes a two position valve (62) connected between the lock-up clutch (32) and the second pump (134) and movable between a first position at which communication between the second pump (134) and the lock-up clutch (32) is blocked and a second position at which the second pump (134) communicates with the lock-up clutch (32), said two position valve (62) being spring biased to the first position and movable to the second position in response to actuation of said single valve (112). 14. The control system (12), as set forth in claim 13, wherein the two position valve (62) includes a pilot actuation chamber (68), and said first valve means (60) further includes a relay valve (138) connected between the pilot actuation chamber (68) and the second pump (134), said relay valve (138) being spring biased to a position blocking communication between the second pump (134) and the pilot actuation chamber (68) and movable to a second position at which said communication between the second pump (134) and the pilot actuation chamber (68) is open, said relay valve (138) being movable to the second position in response to actuation of the single valve (112). 15. The control system (12), as set forth in claim 14, wherein said second valve means (70) includes a dual stage pressure relief valve (72) connected to said first pump (48) and adapted to establish the two distinct pressure levels. 16. The control system (12), as set forth in claim 15, wherein the two stage pressure relief valve (72) includes an actuation chamber (106), and the second valve means (70) further includes a pressure responsive selector valve (108) connected between the first pump (48) and the actuation chamber (106) of the relief valve (72), said selector valve (108) being spring biased to a first position at which communication between the first pump (48) and the actuation chamber (106) is blocked and a second position at which said communication is open, said selector valve (108) being movable to the second position in response to actuation of the single valve (112). 17. The control system (12), as, set forth in claim 16, wherein the single valve means (112) is a solenoid actuated valve movable between a non-actuated position at which fluid from the the first pump (48) is blocked from said relay valve (138) and said selector valve (108) and an actuated position at which fluid from the first pump (48) is free to communicate with said relay valve (138) and said selector valve (108). 18. The control system (12), as set forth in claim 15, wherein the two stage pressure relief valve (72) includes a housing (82) defining a bore (84) therein, an inlet port (86), an outlet port (88) and a signal port (90) located in the housing (82) and intersecting the bore (84); a spool (92) slideably located in the bore (84) and defining an annular groove (98) located between a pair of lands (94,96), an axial bore (100) in one of the pair of lands (94,96), one end of which opens to one end of the spool (92), and a transverse passage (102) connecting the other end of the axial bore (100) to the annular groove (98); a reaction slug (104) slideably disposed in said axial bore (100); and an actuation chamber (106) defined between one end of the bore (84) and the one end of the spool (92), said signal port (90) opening into the actuation chamber (106). 19. The control system (12), as set forth in claim 18, wherein said first pump (48) is connected to the inlet port (86) of the two stage pressure relief valve (72) and said two stage relief valve 72 includes a spring (93) located in the other end of the bore (84), the spool (92) is movable between a first position at which the inlet port (86) is blocked from the outlet port (88) by the other of the pair of lands (94,96), and a second position at which the inlet port (86) is in open communication with the outlet port (88), said spool (92) being movable to the second position in response to the fluid pressure at the inlet port (86) acting through the transverse passage (102) against the reaction slug (104) exceeding the higher of the two distinct pressure levels and the first pump (48) being blocked from the actuation chamber (106), the spool (92) being biased to the first position by the spring (93). 20. The control system (12) as set forth in claim 19, wherein the lower of the two distinct pressure levels is established in response to a fluid pressure signal being communicated to the actuating chamber (106) of the two stage pressure relief valve (72). 21. A transmission assembly and control system, comprising: a power input member (22); a transmission speed ratio section (16); a torque converter (14) coupled with the power input member (22) and the transmission speed ratio section (16), said torque converter (14) including a hydraulically actuated lock-up clutch (32) adapted to selectively bypass the torque converter (14) and effectively couple the input member (22) directly with the transmission speed ratio section (16); a source (47) of pressurized control fluid adapted to supply pressurized fluid to the lock-up clutch (32) and the transmission speed ratio section (16); first valve means (60) for selectively directing pressurized fluid from said source (47) to actuate said lock-up clutch (32); second valve means (70) for controlling the pressure level between the source (47) and the transmission speed ratio section (16) to two distinct pressure levels; and single valve means (112) adapted to simultaneously actuate the first and second valve means (60,70) to respectively actuate the lock-up clutch (32) and reduce the pressure level of the source (47) to the lower of the two distinct pressures in response to the output speed of the transmission (10) exceeding a predetermined speed.