Patent GB-1181497-A (GB)
Title: Drive Selection Control.
IPC: F16D48/06
Filed: 1968-10-25
Abstract: 1,181,497. Clutch control. TWIN DISC Inc. 25 Oct., 1968 [24 Jan., 1968], No. 50778/68. Headings F2D and F2L. In a drive transmission employing alternative power inputs, one of which is engaged through a synchronized positive clutch, provision is made to detect a missed clutch engagement due to tooth interference and automatically to initiate a new engagement cycle including separation of the clutch elements, controlled slipping of the synchronizing clutch to change the relative angular setting of the elements and reactuation of the clutch in the changed condition. Transmission details (Fig. 1).-The arrangement shown provides low and high speed drives for a propeller shaft 10 by a diesel engine 11 and gas turbine 12 operating through spur gearing 18, 25, 28, 29, 30. The engine 11 is controlled by an hydraulically operated disc clutch 13 and the turbine 12 by a positive clutch 15 having a synchronizing disc clutch 14. The movable hub element 33 of clutch 15 moves between fixed proximity sensors I1, 12, and a speed sensor 84 is associated with propeller shaft 10. Control system.-(a) Hydraulic (Fig. 6)- Disc clutch 13 is actuated by pressure liquid supplied to chambers 39, 79 through lines 48, 49 from a pump 52 controlled by solenoid valves 50, 58. The circuit also includes a relief valve 59 and line constriction 61. Pressure chamber 68 of synchronizing clutch 14 is supplied by a second pump 65 through line 67 and a solenoid valve 63, with associated relief valve 70 and line constriction 71. Pressure chamber 42 of positive clutch 15 is supplied through a line 72 and series connected high-pressure solenoid valves 73, 74, and relief valve 75. A further relief valve 81 is associated with a solenoid valve 82. The circuits are interconnected by a line 62 having a branch 78 communicating with the interconnected retraction chambers 80, 80a of clutches 14, 15. (b) Electric (Fig. 5)-The several control valves are actuated by solenoids S1 . . . S6 arranged in circuit with diodes D1 . . . D5 and timers TD1 ... TD6, three command switches SW1, SW2, SW3 being provided for initiating transition from diesel to turbine drive, initiating turbine disengagement, and engaging the diesel drive respectively. Operation.-To engage diesel clutch 13 switch SW3 is closed to complete a circuit between lines L1, L2 through a first switch I1c and a second switch RCP (closed by sensor 84 when the speed of propeller shaft 10 falls below a predetermined value), a relay CR4 closing further switches CR4a . . . CR4c. This results in immediate operation of solenoid S6 and valve 50 to admit low-pressure liquid to chamber 39 followed, through the action of timer TD5, by the slightly delayed operation of solenoid S5 and valves 58, 59 to admit the full operating pressure to chamber 39 for engagement of clutch 13. To change from diesel to turbine drive switch SW1 is closed, relay CR1 operating to close switches CR1a ... CR1c, switch CR1b operating through diode D1 to energize solenoid S1 open valve 63 and deliver pressure liquid through line 67 to chamber 68 to engage synchronizing clutch 14. Upon the turbine speed rising to a preselected value the sensor 85 initiates operation of a timer TD1 which in turn causes energizing of solenoids S3, S4 to open valves 73, 74 and admit pressure liquid to chamber 42. If the clutch elements fully engage the proximity sensor I1 operates switches I1a ... I1c in sequence to cut out all the valve solenoids, disengaging clutches 13, 14 and leaving clutch 15 held engaged by a spring detent 44a. If the clutch elements fail to engage within a given period a timer TD2 cuts out solenoid S3 and valve 73, while maintaining energizing of solenoid S4 and also energizing solenoid S2 and opening valve 82, thus increasing the pressure in lines 62, 78 and chamber 80a to disengage clutch 15. Solenoids S1 S5, S6 are not affected so that engagement of clutches 13, 14 is maintained. When hub 33 of clutch 15 is fully retracted proximity sensor 12 operates a timer TD6 cutting out solenoid S1 and valve 63, venting chamber 68 of synchronising clutch 14 so that the latter slips momentarily. Timer TD6 then recloses switch CR41a to initiate re-engagement of clutch 14, missed engagement procedure being repeated automatically if necessary until free tooth positioning of the clutch elements permits full axial movement of hub member 33. To revert to diesel from turbine drive switch SW2 is closed, to first energize solenoid S1 and engage synchronizing clutch 14 to unload clutch 15, followed by retraction of clutch hub 33 and re-engagement of clutch 13 when the speed falls to a safe value.