High pressure pump for fuel injection systems.

摘要

A variable displacement high pressure pump for pumping fluid at a high pressure to an accumulation chamber is disclosed including a low pressure supply pump for supplying fluid at a low pressure, a first high pressure pumping unit for receiving the low pressure fluid through an inlet and selectively delivering the supply fluid to the accumulation chamber at a high pressure greater than the low pressure and a second high pressure pumping unit for receiving the low pressure fluid through an inlet and selectively delivering the supplied fluid to the accumulation chamber at a pressure greater than the low pressure. A common fluid passage is in fluid communication with each of the first and second high pressure pumping units for permitting the flow of fluid from one to the other of the high pressure pumping units. A pressure balanced valve positioned in the common fluid passage selectively blocks the flow of fluid between the first and second high pressure pumping units such that one of the first and second high pressure pumping units delivers fluid at the high pressure to the accumulation chamber when the valve blocks the flow of fluid between the first and second high pressure pumping units. <IMAGE>