US 3,952,510 A · Flow sensing and control apparatus

Abstract

Flow sensing and control apparatus is provided to selectively combine the fluid output of an auxiliary pump with a hydraulic system. The apparatus includes a valve body having a primary pump passage therein through which fluid from one of a pair of primary pumps is conducted to its respective inlet of a control valve, an auxiliary pump passage interconnected between the auxiliary pump and the primary pump passage and a fluid receiving passage which is connected to the auxiliary pump passage. A pilot operated valve is disposed within the fluid receiving passage and operative in response to fluid flow through the primary pump passage for selectively controlling fluid to the fluid receiving passage so as to permit the combining of any available fluid from the auxiliary pump with that of the primary pump up to a predetermined minimum flow rate through the primary pump passage and for diverting any excess fluid from the auxiliary pump to the receiving passage above that necessary to maintain the minimum flow rate.

Claims26

Dependent claims

Flow sensing and control apparatus, for use in combination with a hydraulic system including a pair of primary pumps and a control valve having a separate inlet for each of such pumps, to selectively combine the output of an auxiliary pump with such hydraulic system, comprising;

a valve body having a primary pump passage through which fluid from one of said primary pumps is conducted to its respective inlet of the control valve, auxiliary pump passage means interconnected between the auxiliary pump and said primary pump passage, and fluid receiving passage means connected to said auxiliary pump passage means;
and
pilot operated valve means disposed within said fluid receiving passage means and operative in response to fluid flow through said primary pump passage to selectively control the admission of fluid to the fluid receiving passage means so as to permit the combining of any available fluid from the auxiliary pump with that of the primary pump up to a predetermined minimum flow rate through the primary pump passage and to permit diversion to the receiving passage means of any excess fluid of the auxiliary pump above that necessary to maintain said minimum flow rate in the primary pump passage.

A hydraulic steering system for a self-propelled vehicle comprising;

a fluid supply reservoir;
a pair of positive displacement engine driven pumps connected for drawing fluid from said reservoir, said pumps being of different volumetric capacities to define a large pump and a small pump;
motor means connected for steering said vehicle;
a manually actuatable double pump steering control valve having a pair of inlets for separately receiving fluid from said small and large pumps, said control valve being positionable for selectively directing fluid only from said small pump to the motor means for making small steering corrections of the vehicle while freely discharging fluid from the large pump to the reservoir and for variably combining fluid from the large pump with that of the small pump for making larger steering corrections;
conduit means for individually connecting said small and large pumps with their respective inlets of the control valve;
an auxiliary ground driven pump;
and
flow sensing and control means connected to said conduit means and responsive to fluid flow from the small pump to its respective inlet of the control valve for selectively combining fluid from the auxiliary pump with that of the small pump whenever fluid flow to the small pump inlet is below a predetermined minimum flow rate.

5 more elements

In a hydraulic steering system of the type having two engine driven pumps of different volumetric capacities defining a large pump and a small pump, a double pump steering control valve with two fluid inlets, and a pair of conduits to individually connect each of the pumps with a respective one of the inlets of the control valve, and wherein the control valve is effective in utilizing the output of only the small pump for making small steering corrections while freely discharging the output of the large pump and variably combining the output of the large pump with that of the small pump for making larger steering corrections, the combination comprising:

an auxiliary ground driven pump;
and
flow sensing and control means connected to said auxiliary pump and disposed witih each of said conduits, said means being responsive to fluid flow through the small pump conduit and operative to selectively communicate any available output of the auxiliary pump to the small pump conduit until a predetermined minimum flow rate sufficient for making small steering corrections is satisfied and to communicate any excess output thereof to the large pump conduit.

Dependencies are inferred from the claim text.

Flow sensing and control apparatus

Life of this patent

Flow sensing and control apparatus

Life of this patent

Abstract

Claims26