Patent GB-1219327-A (GB)
Title: A change speed control device for an automatic transmission control system of automotive vehicles
IPC: F16H61/08
Filed: 1968-03-07
Abstract: 1,219,327. Change speed control. TOYO KOGYO K.K. 7 March, 1968 [7 March, 1967], No. 11240/68. Heading F2D. A speed change control device in an automatic transmission system comprises a first detector 25, Fig. 2a which provides a signal in response to the speed of a drive shaft 7, Fig. 1, a second detector device 26 provides a signal in response to the speed of a driven shaft 19, a shift valve 27, Fig. 2b, directs pressure fluid to first and second servomotors 29, 17 to engage a high speed power train and disengage a low speed power train and a downshift control valve 30 coupled to the first and second detectors controls, in dependence on the speed of the shafts, the time interval between the disengagement of the second servomotor and the engagement of the first servomotor when the shift valve is operated to exchange the high speed power train for the low speed power train. An engine 1 drives a pump 4 of a torque converter having a stator 6 and a turbine 5 driving a second drive shaft 7. A two-stage forward and one stage reverse speed change gear 8 has front and rear sun gears 9, 10, rear and front pinions 11, 12, a cage 13 fixed to a driven shaft 19 and a ring gear 14 which is held by a frictional member 18 for reverse. The second drive shaft 7 and the drum 16 are connected by the engagement of a frictional member 17, the drum 16 being connected to the front sun gear 9. Idling.-At idling speed the input pump 20, Fig. 2a, supplies oil from tank 21 to the opening 58 in the main adjusting valve 23 and to opening 103 in the manual valve 28. From opening 58 line pressure is supplied to opening 40 of the throttle valve TV (throttle variable) 24 and, since the manual valve 28 is in neutral, no oil is supplied to frictional members 15, 17 which remain disengaged and drive is not transmitted from the engine 1 to the driven shaft 19. Starting.-Manual valve 28 is moved into the driving range (D) to supply line pressure from opening 103 to opening 108 of the low servo valve 29. Piston 110 moves against its spring loading to engage the frictional member 15 with drum 16, Fig. 1, so that the drive is transmitted from the engine 1 to the driven shaft 19 through the second driving shaft 7, the rear sun gear 10, the pinions 11, 12 and the cage 13. The speed change gear 8 assumes the low speed forward driving state and the vehicle moves off. Low speed running.-When the vehicle runs the weights 88, 89 of the front and rear governor valves 25, 26 act centrifugally to move pistons 76, 76 outwardly from shafts 7 and 19. This connects openings 91 and 93 to grooves 82 or 83 so that part of the line pressure is supplied to the opening 142 of the downshift control valve 30 as the front governor pressure and a further part of the line pressure is supplied to the opening 141 of the downshift controlling valve 30 as the rear governor pressure, piston 136 being pushed leftwards. At the same time this pressure is supplied to the opening 119 of shift valve 27 to push the piston 114 leftwards. Low speed to high speed upshift.-As the speed of the driven shaft 19 increases the rear governor pressure (see above) increases until piston 114 moves to the left against the combined force of spring 118 and the throttle pressure. This connects openings 120, 122 through groove 117 and a part of the line pressure from conduit 64 is supplied to the high speed frictional member 17 through a constriction 126. At the same time oil is supplied through a check valve 128 to the opening 131 of the low servo 29. Piston 133 is moved to the right to cause engagement of the frictional member 17 and when this movement almost stops the raised pressure in pipe 129 causes the piston 110 to move to the left to disengage the frictional member 15. The speed change ratio is smoothly upshifted to high speed forward drive and the speed of shaft 7 is lowered accordingly, the speed of shaft 7 and shaft 19 are equal after the upshift. High speed running state.-When the front and rear governor pressures become equal the pressure on the right hand end of piston 136 overcomes the counter pressure and spring force on its left hand end and it moves to the left. The piston portion 137 closes opening 143, 144 to block pipes 129, 130. High speed running to low speed running downshift.-On speed reduction the rear governor pressure is lowered and piston 114 of shift valve 27 is moved to the right by spring force and throttle pressure. Piston portion 116 blocks opening 120 and piston portion 115 opens opening 123. Oil in the frictional member 17 is quickly discharged to the oil tank through check valve 148, opening 122 and opening 123. Piston 136 of the downshift valve 30 is not displaced because of the simultaneous lowering of the front governor pressure. Frictional member 17 is disengaged and the speed change 8 is set in neutral. This causes a rise in the engine speed and consequently in the front governor pressure which, assisted by spring pressure, moves piston 136 to the right overcoming the rear governor pressure. The oil on the spring side of the low servo valve 29 is discharged to the oil tank via openings 131, 144, groove 139, opening 143, check valve 148 opening 122, groove 117 and opening 123. Piston 110 is then moved to the right by the line pressure of the low servo 29 causing the frictional member 15 to engage drum 16 for low speed forward drive. The device may be applied to forward three or four stage automatic speed change gear.