Load responsive system with area change flow extender

A load-responsive hydraulic system of the type which includes a source of fluid having a pump that delivers pressurized fluid at the fluid pressure thereof and a sump that receives fluid at the fluid pressure thereof, a fluid-actuated device, a directional control valve having a body that is connected to said source to receive fluid therefrom at said pump pressure and to deliver fluid thereto at said sump pressure and having a movable valving element that is movable to a standby position wherein said fluid-actuated device is isolated from said pump and to an operating position wherein pressurized fluid is supplied from said pump to said device at the load-actuating pressure thereof, and a differential pressure actuated bypass valve having a housing that is connected to said source for bypassing of fluid from said pump to said sump and having a valve spool that includes both a first fluid-responsive area connected to said pump for actuating said valve spool to a bypassing mode by said pump pressure wherein said pump fluid is bypassed to said sump and a second fluid-responsive area for actuating said valve spool to an operating mode wherein said bypassing is occluded, the improvement which comprises:

• a third fluid-responsive area in said bypass valve, being operably connected to said valve spool, and being effective to actuate said valve spool to one of said modes by a force that is proportional to the fluid pressure applied thereto and by a distance proportional to the movement thereof;
• second area signal means, including a first signal port in said control valve that is connected to said second fluid-responsive area and including said valving element, for establishing a first fluid flow path in said control valve between said first signal port and said fluid-actuated device to sense said load-actuating pressure thereby, for applying said load-actuating pressure and the changes thereof to said second area when said control valve is in said operating position, and for attenuating said load-actuating pressure that is applied to said second area when said control valve is in said standby position;
• and
• third area signal means, including a second signal port in said control valve and including said valving element, being connected to said third fluid-responsive area and to said sources, and being responsive to said pump pressure, for establishing a second fluid flow path from said second signal port to said source, for applying said pump pressure to said third area when said control valve is in one of said positions, and for applying another of said pressures to said third area when said control valve is in the other of said positions.

A load-responsive hydraulic system of the type which includes a source of fluid having a pump that delivers pressurized fluid at the fluid pressure thereof and a sump that receives fluid at the fluid pressure thereof, a fluid-actuated device, a directional control valve having a body that is connected to said source to receive fluid therefrom at said pump pressure and to deliver fluid thereto at said sump pressure and having a movable valving element that is movable to a standby position wherein said fluid-actuated device is isolated from said pump and to an operating position wherein pressurized fluid is supplied from said pump to said device at the load-actuating pressure thereof, and a differential pressure actuated bypass valve having a housing that is connected to said source for bypassing of fluid from said pump to said sump and having a valve spool that includes both a first fluid-responsive area connected to said pump for actuating said valve spool to a bypassing mode by said pump pressure wherein said pump fluid is bypassed to said sump and a second fluid-responsive area for actuating said valve spool to an operating mode wherein said bypassing is occluded, the improvement which comprises:

• a third fluid-responsive area in said bypass valve, being operably connected to said valve spool, and being effective to actuate said valve spool to one of said modes by a force that is proportional to the fluid pressure applied thereto and by a distance proportional to the movement thereof;
• second area signal means, including a first signal port in said control valve that is connected to said second fluid-responsive area and including said valving element, for establishing a first fluid flow path in said control valve between said first signal port and said fluid-actuated device to sense said load-actuating pressure thereby, for applying said load-actuating pressure and the changes thereof to said second area when said control valve is in said operating position, and for attenuating said load-actuating pressure that is applied to said second area when said control valve is in said standby position;
• and
• third area signal means, including a second signal port in said control valve and including said valving element, being connected to said third fluid-responsive area and to said source, and being responsive to said pump pressure, for establishing a second fluid flow path from said second signal port to said source, for applying said pump pressure to said third area when said control valve is in one of said positions, and for applying said load-actuating pressure to said third area when said control valve is in the other of said positions.

A load-responsive hydraulic system of the type which includes a source of fluid having a pump that delivers pressurized fluid at the fluid pressure thereof and a sump that receives fluid at the fluid pressure thereof, a fluid-actuated device, a directional control valve having a body that is connected to said source to receive fluid therefrom at said pump pressure and to deliver fluid thereto at said sump pressure and having a movable valving element that is movable to a standby position wherein said fluid-actuated device is isolated from said pump and to an operating position wherein pressurized fluid is supplied from said pump to said device at the load-actuating pressure thereof, and a differential pressure actuated bypass valve having a housing that is connected to said source for bypassing of fluid from said pump to said sump and having a valve spool that includes both a first fluid-responsive area connected to said pump for actuating said valve spool to a bypassing mode by said pump pressure wherein said pump fluid is bypassed to said sump and a second fluid-responsive area for actuating said valve spool to an operating mode wherein said bypassing is occluded, the improvement which comprises:

• a third fluid-responsive area in said bypass valve, being operably connected to said valve spool, and being effective to actuate said valve spool to one of said modes by a force that is proportional to the fluid pressure applied thereto and by a distance proportional to the movement thereof;
• second area signal means, including a first signal port in said control valve that is connected to said second fluidresponsive area and including said valving element, for establishing a first fluid flow path in said control valve between said first signal port and said fluid-actuated device to sense said load-actuating pressure thereby, for applying said load-actuating pressure and the changes thereof to said second area when said control valve is in said operating position, and for attenuating said load-actuating pressure that is applied to said second area when said control valve is in said standby position;
• and third area signal means, including a second signal port in said control valve and including said valving element, being connected to said third fluid-responsive area and to said source, and being responsive to said pump pressure, for establishing a second fluid flow path from said second signal port to said source, for applying said pump pressure to said third area when said control valve is in one of said positions, and for applying said sump pressure to said third area when said control valve is in the other of said positions.