| 摘要 |
A reversible motor is coupled to the stern leg of a watercraft for angulating the leg up and down through a trim and tilt range. A manually settable device provides a voltage signal corresponding to the desired trim angle and a position sensor provides a voltage signal corresponding to the present stern leg position. A first comparator changes the state of its output if the difference between the signals has one polarity and a second comparator changes state for the opposite polarity. The state changes turn on one of two transistor switches which provide an up or a down signal, respectively, to a motor control circuit for causing the motor to run until the difference is nulled. When the active transistor switch turns off, the other delivers a momentary pulse for plugging the motor. The switching transistors are supplied from a power source through up and down tilt control push button switches which, when operated, remove power from the transistor switches and the entire trim control circuit and disable the trim function. The position signal and another reference signal, corresponding to the upper trim limit, are fed to a third comparator such that if the stern leg is tilted out of the permissible trim range any state changes of the first and second comparators are nullified to thereby disable the trim function. Other comparators nullify the trim function in response to an electric circuit failure. The trim control remembers where it was set and restores the stern leg to the trim angle existing at the time the tilt function overrode the trim function by disabling the latter. |
