Vaccum operated dry sump system

A system for supplying hydraulic fluid to the inlet of a pump, comprising:

• a sump adapted to receive and contain fluid;
• a reservoir adapted to contain hydraulic fluid having a volume located above fluid in the reservoir;
• a vacuum source communicating with the volume of said reservoir above the fluid therein;
• means hydraulically connecting the sump and the reservoir;
• an electrical power source;
• first and second fluid level sensor switches connected to the electrical power source for producing signals representing the level of fluid in the reservoir in accordance with the state of said switches;
• a solenoid;
• a hydraulic switching valve having inlet ports connected to the sump and reservoir, an outlet port connected to the pump, a valve spool moved by the solenoid between a first state where the reservoir is connected to the pump and the sump is disconnected from the pump and a second state where the sump is connected to the pump and the reservoir is disconnected from the pump;
• switching means for changing the conductive state of the solenoid through the electrical power source;
• logic circuit means driving the switching means, responsive to the state of the fluid level switches for connecting fluid in the reservoir to the pump if the fluid level in the reservoir is high and for connecting the sump to the pump if the fluid level in the reservoir is low.

A system for supplying hydraulic fluid to the inlet of a pump, comprising:

• a sump adapted to receive and contain fluid;
• a reservoir adapted to contain hydraulic fluid having a volume located above fluid in the reservoir;
• a vacuum source communicating with the volume of said reservoir above the fluid therein;
• means hydraulically connecting the sump and the reservoir;
• fluid level sensor means for indicating the level of fluid in the reservoir;
• switching valve means responsive to the indicated fluid level in the reservoir for connecting the fluid in the reservoir to the pump if the fluid level in the reservoir is high and for connecting the sump to the pump if the fluid level in the reservoir is low;
• an engine intake manifold;
• vacuum regulator means located between the intake manifold and the reservoir for maintaining a minimum vacuum in the reservoir sufficient to draw fluid from the sump into the reservoir;
• first check valve means to prevent flow of gaseous fluid from the vacuum pressure source to the reservoir;
• and
• orifice means for limiting the flow rate from the reservoir to the vacuum source;
• filter means located between the switching valve means and the pump for filtering contaminants from the fluid;
• heat exchanger means located in the reservoir for transferring heat between the fluid in the reservoir and engine coolant flowing through the heat exchanger.