Flow sensing auxiliary pump by-pass valve

Abstract

A valve for use in a system having a source of fluid, two pumps and means responsive to a change in the flow condition of the fluid caused by a lack of proper performance of one of the pumps to effect a utilization of the fluid pumped by the other pump. The valve includes a body having a pair of inlet ports and an outlet port spaced from the inlet ports. One of the pumps is connected to a first inlet port with the other pump being connected to a second inlet port. A passageway is provided in the valve body and extends between and is in fluid communication with the pair of inlet ports and the outlet port. A first normally closed valve is provided in the valve body for controlling the main flow of fluid from one of the pumps and is openable in response to a predetermined pressure differential in the fluid at the first inlet port and the outlet port. The first normally closed valve is closed, in addition to the normal closing thereof, in response to a fluid flow from the other pump. A second normally closed valve is provided in the valve body for controlling the return flow of the fluid from the other pump to a reservoir therefor. The second valve is openable in response to a predetermined pressure differential in the fluid at the first inlet port and the outlet port to effect a return of fluid to the reservoir. The second valve is closed, in addition to the normal closing thereof, in response to a drop in the predetermined pressure differential in the fluid to effect both a blocking of the return flow of the fluid to the reservoir and initiating a flow of fluid from the other pump to the outlet port.