Patent GB-439486-A (GB)
Title: Improvements in and relating to the control of internal combustion power plants
IPC: F01L1/00
Filed: 1934-04-03
Abstract: 439,486. Regulating; plant. LEYLAND MOTORS, Ltd., Richmond Road, Kingston-on-Thames, and LUCY, B., Motor Works, Hough Lane, Leyland, Lancashire. April 3, 1934, No. 10039. [Classes 7 (ii) and 7 (vi)] [See also Groups XXXI and XXXV] Relates to pneumatic apparatus for controlling a plurality of internal-combustion engines from a distance comprising an air pipe, a hand-controlled valve governing the pressure in said pipe, and a pneumatic servomotor operating each engine throttle. According to the invention, (1) the servomotor opens the throttle to idling position under a small pressure in the pipe and does not open it further until there is a substantial increase in the pressure, (2) servomotors for each engine open the throttle wide under a low pressure in the pipe and are further controlled by the starting of the engine to return the throttle to the idling position, and (3) servomotor means for each engine open the throttle and start the engine under a low pressure in the pipe, but are auto. matically disconnected from the pipe, when an engine auxiliary fails, by means of an electricallyoperated valve controlled by the engine auxiliary. Thus the valve is operated and the engine shut down if either the engine cooling or lubricating system breaks down. In the construction shown, an air reservoir is connected to a train pipe 2 by a hand-controlled valve 3, the opening of which determines the pressure in the pipe. The throttle valve (not shown) of each engine is controlled by a link 9 connected to a lever 7 operated by a servomotor 5 connected by a branch pipe to the pipe 2. The branch pipe is normally open, but may be closed by an electrically-controlled valve 6. When the valve 3 is opened to its first position, air at (say) 15 per cent of reservoir pressure is admitted to the servomotor 5 and the lever 7 is operated against the resistance of a spring 8 and moves the throttle to the idling position, further movement of the lever being now opposed by an additional spring 10. The low pressure in the pipe 2 also operates a servomotor 13 to move a switch 14 from position a to position b to complete the circuit of a contactor 16 through a centrifugal switch 21 and a normally-closed contactor 18. The contactor 16 closes the circuit of the starting- motor 17 which then rotates the internalcombustion engine. Simultaneously, the engine throttle is fully opened by an auxiliary servomotor 11 which is of greater power than the servomotor 5, the auxiliary servomotor being connected to the train pipe by an electricallyoperated valve 12, normally closed but opened when the circuit for the contactor 16 is completed. As soon as the engine is running, the centrifugal switch 21 opens and breaks the circuits of the contactor 16 and the coil which has opened the valve 12. Thus the circuit of the starter motor is broken by the contactor 16, and the valve 12 closes to de-energize the auxiliary servomotor 11 and allow the throttle to return to the idling position, in which it is held by the servomotor 5. Emergency switches 19, 20 are provided which are normally open, but close in case of defective working of the engine, such as cooling, lubrication, or other failures. If either of these switches closes, it completes a circuit for (1) the contactor 18 so that the starter-motor circuit cannot be completed, and (2) the coil of the valve 6 so that this valve closes, the servomotor 5 is deenergized, and the engine throttle closes. The train pipe 2 is also used to connect the engine to its load, and to vary the speed ratio of the connection, as by engaging successive stages of a variable gear. For this purpose, the clutch and gear may be controlled by servomotors directly connected to the train pipe so as to come into action as the pressure increases, or the servomotors may be controlled electrically, as by the switch 14. This switch may have positions c, d in which it controls pneumatic means as described in Specification 434,537, [Group XXXI], for bringing into operation an hydraulic torque converter and for direct drive. In the positions a and b, the switch closes a circuit through a line 22 which ensures that the engine is disconnected from the load; hence the starting-gear cannot be put into action unless the engine is free. When the handle 4 of valve 3 is moved to its second position, the pressure in the train pipe 2 is increased (say) to 25 per cent of the receiver pressure. The servomotor 5 is still unable to overcome the resistance of spring 10, so that the throttle remains in the idling position. Servomotor 13 now moves switch 14 to position c, in which, at low speeds, a circuit is completed through a switch 25 and a line 23 to couple the engine to the load through the torque converter. Further movement of the handle 4 increases the train-pipe pressure so that the engine throttle is opened by the servomotor 5 and the switch 14 is moved to position d, in which the circuit 23 is still completed. As the vehicle speed increases, a centrifugal governor 26 moves the switch contacts 25 and breaks the circuit 23. If the handle 4 is now moved back to reduce the pressure in the train pipe, the throttle closes to the idling position and the switch 14 moves back to position c, in which a direct-drive circuit 24 is completed through the left-hand position of the contacts 25, so that the change-over to the direct drive is made with the throttle nearly closed. The speed at which the contacts 25 are operated by the governor is partly under the driver's control, the governor spring 27 being controlled by a piston 28, movement of which is caused by the train-pipe pressure and opposed by another spring 29. Thus, by increasing the pressure in the train pipe, even beyond that required to open the throttle fully, the speed limit at which the governor acts may be raised. When the direct drive is in use, the driver may bring the indirect drive into use by thus increasing the pressure in the train pipe and thereby moving the contacts 25 to the right. Modifications are described in which (1) the auxiliary servomotor 11 is operated directly by the main receiver pressure instead of by the reduced train-pipe pressure, (2) the gear-control switch 25 is replaced by two switches, one controlled by the vehicle speed and the other by the trainpipe pressure ; by the use of additional contacts the centrifugal switch may bring the direct drive into action independently of the driver when a predetermined vehicle speed is attained. When reversing-gear is provided, this may be controlled by separate electric circuits as described in the above-mentioned Specification 434,537.