| 摘要 |
1,120,671. Variable-pitch marine-propellers. BLOCTUBE CONTROLS Ltd. 23 May, 1966 [4 June, 1965], No. 23990/65. Heading B7V. Pitch-control apparatus for a variable-pitch marine-propeller 2 that is driven by a diesel engine 1 comprises a control pedestal 3 carrying an engine-speed control-lever (4), Fig. 2 (not shown), and a propeller-pitch control-lever 5, the apparatus being such that when the engine is overloaded the propeller pitch is automatically reduced enough to remove the overload. In this apparatus a propeller-pitch control-unit 33 is pneumatically operated to effect a change of pitch in response to movement of the lever 5 from its neutral position (as shown) in a direction A or B according to the desired direction of propulsive action, i.e. ahead or astern, displacement of the lever being communicated to said unit accordingly by compressed-air lines 30, 31 and an air-operated valve 6 or 7 that is regulated by a cam unit 20 coupled to the lever. The cam unit also regulates further valves 8, 9 in air lines 34 connected to pneumatically-operated piston- and-cylinder units 13, 14 that are attached to slotted links 11, 12 respectively, the said links being engaged by a member 10 connected to the lever 5. When the lever 5 is displaced from its neutral position one or other of the valves 8, 9 is opened accordingly to admit atmospheric air to the corresponding unit 13 or 14 so that compressed air supplied thereto through an air line 40 and a pressure-reducing valve 41 renders the unit in a retracted condition (as shown). If the engine becomes overloaded a so-called fuel rack 16 associated therewith causes a valve 15 to admit compressed air to the lines 34 through an air-line 21 so that the appropriate unit 13 or 14 operates against the action of a dashpot 42 and moves the corresponding slotted link 11 or 12 to shift the member 10 and the lever 5 towards the neutral position. Such movement of the lever 5 effects reduction of the propeller pitch until the rack 16 is moved in response to the reduction of load on the engine and causes the valve 15 to vent the lines 34 to the atmosphere whereby the actuated unit 13 or 14 is restored to its normal retracted condition without altering the new position of the lever 5. The links 11, 12 are such that the lever has complete freedom of movement in either direction when the units 13, 14 are in a retracted condition. The member 10 may be constituted by a rack-and-pinion unit (53); and the unit 20 is connected to the lever 5 by shafting (50), Fig. 3 (not shown), and gearing (51). The valve 15 may be either of the poppet type or solenoid operated, the solenoid being controlled by a switch that is actuated by the rack 16. |
