Patent ID: 6298820
Filing Date: 2001-10-09
Classification: F02B,F02D,F04B,F04C,F04D

Abstract:
A method of automatically limiting an operating speed of a fluid displacement unit having a fluid pump powered by a combustion engine using an automatic shut-off and reset control circuit, the automatic shut-off and reset control circuit providing a frequency acceptance window and an attention electrical signal, the method comprising the steps of:a) receiving an input electrical signal representative of the operation of the fluid displacement unit, the input electrical signal being cyclical in nature and having a frequency representative of a current operating speed of the fluid displacement unit;b) deriving electrical power from the input electrical signal to be stored and to drive components of the automatic shut-off and reset control circuit;c) generating the frequency acceptance window representative of a range of allowable frequencies of the input electrical signal, the frequency acceptance window having a maximum cut-off frequency representative of a maximum allowable operating speed of the fluid displacement unit;d) generating the attention electrical signal characterized by an increasing potential, the attention electrical signal being adapted to reach a shut-off threshold level potential over a period of time at least as long as one cycle of the input electrical signal when the frequency of the input electrical signal represents the maximum allowable operating speed of the fluid displacement unit;e) selectively decreasing the potential of the attention electrical signal to a minimum potential level preventing the attention electrical signal from reaching the shut-off threshold level potential if the frequency of the input electrical signal is within the frequency acceptance window;f) selectively inhibiting fuel ignition in the combustion engine if the potential of the attention electrical signal exceeds the shutoff threshold level potential; andg) enabling manual restart of the fluid displacement unit by re-enabling fuel ignition in the combustion engine subsequent to the combustion engine spinning down to a rest.