GB848484A - Improvements in or relating to internal combustion engines - Google Patents

Abstract

848,484. Starting. MOTORENWERK CUNEWALDE VEB. Oct. 21, 1957, No. 32847/57. Class 7(5). [Also in Group XXVI] A decompression device for a four-stroke internal combustion engine which operates automatically to prevent compression in the event of the faulty circulation of the-engine lubricating oil comprise inlet and exhaust valve cams 5, 7, a starting cam 6, a common rockershaft 2 having a spring 4 for urging it to a position to co-operate with the starting and exhaust cams 6, 7 on the cam-shaft 1, and control means 11 sensitive to engine oil pressure for moving the rocker-shaft against the spring 4, the control means being such that whilst the engine is running the rocker-shaft is maintained by oil pressure in its operative position relative to the inlet and exhaust valve cams 5, 7, but in the event of a drop in pressure the spring 4 moves the shaft 2 to the right so that the exhaust valve is held off its seat to stop the engine by a collar 17 on its push-rod 16 engaging with a stop 13 which is brought into operative position by a lever 8, 8a and plunger 12. Fig. 1 shows the system in readiness for starting with the stop 13 engaging the collar 17 and, at its lower end, in contact with a plunger 11 on which the oil pressure operates to retain the decompression device in the disengaged position as shown in Fig. 3. The lever 8 is mounted on a spindle 9, Fig. 6 slidable on an axis at right angles to the rockershaft 2; when in the starting position the lower end 8b of the lever 8 bears on a collar 14 at the base of a cone 15 formed at the right hand end of the rocker shaft, the inlet valve push-rod 18 then being operated by the starting valve cam 6. After starting, the spindle 9 is moved axially by a handle 19, Fig. 6, to bring the arm 8b of the lever 8 into contact with the apex of the cone 15 to retain the rocker-shaft 2 in its normal running position by the oil pressure acting in opposition to the spring 4.