Flow volume control device for a power assisted steering device

A flow volume control device for supplying pressurized fluid from an engine-driven pump to a power assisted steering device and for returning an excess part of said pressurized fluid directly to said pump, comprising:

• inlet passage means for conducting said pressurized fluid exhausted from said pump, said inlet passage means having a predetermined resistance against the flow of said pressure fluid;
• outlet passage means fluidically communicating with said steering device;
• first throttle means permanently opened;
• second throttle means provided in parallel circuit relation with said first throttle means;
• bypass passage means connected to said pump for returning said excess part of said pressurized fluid to said pump;
• main volume control means interconnected between said inlet and bypass passage means and having a main valve element movable in response to said pressurized fluid flowing from said inlet passage means to said first and second throttle means for permitting said excess part of said pressurized fluid to flow from said inlet passage means to said bypass passage means;
• and
• auxiliary volume control means having an auxiliary valve element which is cooperable with said second throttle means and which is movable independently of said main valve element in response to a pressure drop when an increase in the rotational speed of said pump causes said pressurized fluid passing through said inlet passage to increase in volume, for closing said second throttle means.