Patent GB-1489898-A (GB)
Title: Transmission shifting control system
IPC: F16H59/04
Filed: 1974-12-24
Abstract: 1489898 Transmission locking safety devices NISSAN MOTOR CO Ltd 24 Dec 1974 [24 Dec 1973] 55683/74 Heading B7H A safety device for preventing engagement of a forward gear before a vehicle occupant has observed certain safety procedures, such as fastening a safety belt, includes an electrically operated device which acts to disconnect parts of the transmission shift linkage if the procedures are not observed. The electrically operated device includes a solenoid 28, having a core projection 32, mounted on a select lever 10. Until the solenoid is actuated the projection engages a recess 26 in a linking lever 24 of the shift mechanism. The circuit controlling the solenoid includes a normally open seat switch 82, a switch 86 which is opened when the seat belt 90 is fastened, a NOT circuit 100 which produces a signal C only when the seat switch is open and a memory circuit 102 which produces a signal D when C is produced but produces no signal when both the switches 82, 86 are closed. A starter motor circuit 56 includes switches 64, 66 which prevent starting of the engine unless the transmission is in Neutral or Parking positions. Circuit operation.-Before the driver sits and with the seat belt unfastened switches 82 and 86 are respectively opened and closed. Circuit 10 produces output C which causes memory circuit 102 to give a signal D which is passed to AND gate 104 which is also connected to switch 82. No output E is produced at the AND switch since with switch 82 open no signal A therefrom exists. If the driver now sits switch 82 closes to give a signal A which cancels output C and allows a signal B to be produced at switch 86. Signal B is passed to an OR gate 106 and to the memory unit where it cancels D. Since only signal B exists at the OR gate an output F is produced and this passed to a further AND gate 107 which is also connected to an engine speed sensor 108 which when the engine is operating produces a signal G. When both B and G pass to gate 107 output H is produced to actuate coil 28 and disconnect the transmission linkage parts. If the belt is now fastened signal B is cancelled, since switch 86 opens, so removing signals F and H and de-energizing the coil thus reconnecting the linkage. If the driver fastens his belt before sitting signal D is not cancelled, hence when he does sit signals A and D give the output E at gate 104 which then actuates gates 106 and 107, after starting the engine, to actuate the coil. If he then unfastens and refastens the belt the coil will be de-energized. In a further arrangement (Fig, 4, not shown) the AND switch is further connected to Neutral and Parking switches 64, 66 and possibly to a vehicle speed sensor device, the latter preventing energization of the coil when the vehicle is moving. In a still further arrangement (Fig. 5, not shown) the output from AND gate 107 is connected to a further AND and to a further memory circuit controlled by an ignition switch and connected to the further AND gate. If the driver fails to carry out the precautionary procedure with the ignition switch 58 closed, the selector lever 10 is prevented from being disconnected from the linking lever 24.