| 摘要 |
1480053 Control of D.C. motors LUCAS INDUSTRIES Ltd 11 June 1974 [30 June 1973] 31303/73 Heading H2J The motor control system described with reference to Figs. 1 to 4 of Specification 1,480,064 is provided with means responsive to the speed of the vehicle to prevent regenerative braking when the brake pedal is depressed whilst the speed is below a predetermined value and means to maintain regenerative braking, once commenced, after the speed falls below the predetermined value. In Fig. 5 forward or reverse drive is provided by moving a switch 34 to energize a winding 35 or 36 to close contacts 35a or 36a, the latter directly energizing the reverse contactor device R. Contacts 35a control series-parallel circuits consisting of windings 38, 42 controlling contacts 38a, 42a, 42b, auxiliary contacts F2, B2 of the forward and braking contactor devices F, B, contacts 37, 39 respectively closed when the accelerator and brake pedals are depressed and contacts 41 which close when the vehicle speed is above a predetermined low value. Contacts 43 close when the motor current is above a predetermined value. With switch 34 in the forward position, depression of the accelerator pedal operates relay 38, 38a to energize the device F, whose contacts F2 open to isolate winding 42. Release of the accelerator pedal and depression of the brake pedal causes de-energization of members 38 and F, closure of contacts F2 and energization of winding 42, provided the speed is high enough to close contacts 41, contacts 42a then closing to energize device B, which is maintained energized through contacts 42b, 43 if the current is above the predetermined value, even though the speed may subsequently fall to cause contacts 41 to open. Thus the braking is terminated by the current falling below the predetermined value. In the modification shown in Fig. 6, contacts 37, 39, 41 form the inputs to an AND gate 53 controlling a winding 52, whose changeover contact 51 is normally in a position (with contacts 35a closed) to energize the winding 38 and hence device F, even though the accelerator pedal is not depressed. Thus when this occurs there is a rapid response, with the further advantage in that contactor opening and closing is reduced, as the accelerator and brake pedals are depressed and released at speeds below the predetermined value. Contacts 37 are closed when the accelerator pedal is released so that, if the brake pedal is depressed and the speed is above the predetermined value, the gate 53 energizes the winding 52 to change over contact 51 and energize relay 42, 42a and device B, the current-dependent hold-on circuit 42b, 43 functioning as before. Winding 38 may have hold-on contacts connected to contacts 43. |
