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US 10,927,866 B2Granted
Leakage modulation in hydraulic systems containing a three-way spool valve
AssigneeEaton Intelligent Power Limited
InventorMichael Rannow
Life of this patent
Estimating the term…
Abstract
Hydraulic systems and associated methods configured to reduce leakage past a spool valve when the system is in a neutral state. Leakage reduction is achieved by shifting the spool valve within the spool bore. The shifting direction can depend on whether the system has a relatively high load or a relatively low load in the neutral state. The amount of shifting can depend on the pressure differential between the supply line and the work port, and/or the pressure differential between the work port and the tank line.
Claims17
A hydraulic system, the hydraulic system having an operational state and a neutral state and comprising:
- a fluid supply line having a supply port and being in fluid communication with a work port, the work port being in fluid communication with a tank line, the tank line having a tank port and being fluidly connected to a tank;
- a spool valve having a spool disposed in a spool bore defining an axis, the spool being axially moveable within the bore and being adapted to regulate fluid flow from the supply port to the work port and from the work port to the tank port;
- the spool comprising first and second lands, the first land being positioned to block direct fluid communication from the supply port to the work port when the hydraulic system is in the neutral state, and the second land being positioned to block direct fluid communication to the tank port from the work port when the hydraulic system is in the neutral state;
- the first land defining a supply line deadband distance when the spool is in a centered position relative to the bore and the second land defining a tank line deadband distance when the spool is in the centered position relative to the bore;
- a driver that drives a first axial shifting of the spool when the hydraulic system is in the neutral state and there is a first pressure differential between the supply port and the work port, or that drives a second axial shifting of the spool when the hydraulic system is in the neutral state and there is a second pressure differential between the work port and the tank port,
- the first axial shifting causing the first land to shift towards the tank port, the first axial shifting defining a first distance calibrated to be equal to or not to exceed the tank line deadband distance;
- the second axial shifting causing the second land to shift towards the supply port, the second axial shifting defining a second distance calibrated to be equal to or not to exceed the supply line deadband distance;
- one or more controllers that receives pressure measurements at one or more of the work port, supply port, and tank port, the one or more controllers being adapted to provide operating signals to the driver, the operating signals commanding the driver to drive the first or the second axial shiftings of the spool;
- and
- one or more pressure sensors that detect one or more fluid pressures associated with one or more of the supply port, the tank port, and the work port.
7 more elements
A hydraulic system, the hydraulic system having an operational state and a neutral state and comprising:
- a fluid supply port in fluid communication with a work port, the work port being in fluid communication with a tank port;
- a three-way spool valve, comprising a valve body defining a valve bore, and a spool disposed in the valve bore, the valve bore defining an axis, the spool being axially moveable within the valve bore and being adapted to regulate fluid flow from the supply port to the work port and from the work port to the tank port, the spool including a first land axially separated from a second land by a flow passage, the spool being axially moveable along the axis between first and second positions;
- wherein in the first position the second land blocks fluid communication between the work port and the tank port and the flow passage provides direct fluid communication between the supply port and the work port;
- and
- wherein in the second position the first land blocks fluid communication between the supply port and the work port and the flow passage provides direct fluid communication between the work port and the tank port, the valve being operable in a neutral state where the spool is maintained in a shifted neutral axial position in which:
- a) the first land blocks fluid communication between the supply port and the work port;
- b) the second land blocks fluid communication between the work port and the tank port;
- and c) the spool has first and second deadband distances having different magnitudes, the first deadband distance being equal to a first axial distance the spool is required to travel to open fluid communication between the supply port and the work port, and the second deadband distance being equal to a second axial distance the spool is required to travel to open fluid communication between the work port and the tank port.
5 more elements
A hydraulic system, the hydraulic system having an operational state and a neutral state and comprising:
- a fluid supply line in fluid communication with a work port, the work port being in fluid communication with a tank line connected to a tank;
- a spool valve having a spool disposed in a spool bore defining an axis, the spool being axially moveable within the bore and being adapted to regulate fluid flow from the supply line to the work port and from the work port to the tank;
- a driver that drives a first axial shifting of the spool when the hydraulic system is in the neutral state and there is a first pressure differential between the supply line and the work port, or that drives a second axial shifting of the spool when the hydraulic system is in the neutral state and there is a second pressure differential between the work port and the tank line;
- the spool axially biased relative to a neutral position of the spool in relation to the bore when the system is in the neutral state;
- and
- wherein the neutral position is an off-centered position relative to the bore.
3 more elements
A hydraulic system, the hydraulic system having an operational state and a neutral state, and comprising:
- a fluid supply line having a supply port and being in fluid communication with a work port, the work port being in fluid communication with a tank line having a tank port and being connected to a tank;
- a spool valve having a spool disposed in a spool bore defining an axis, the spool being axially moveable within the bore and being adapted to regulate fluid flow from the supply line to the work port and from the work port to the tank;
- and
- a driver that drives a first axial shifting of the spool from a first position to a second position when the hydraulic system is in the neutral state, the first axial shifting being in response to a detected first pressure differential between the supply port and the work port, or that drives a second axial shifting of the spool from a third position to a fourth position when the hydraulic system is in the neutral state, the second axial shifting being in response to a detected second pressure differential between the work port and the tank port,
- wherein at each of the first position, the second position, the third position, and the fourth position, the spool blocks the supply port and the tank port.
2 more elements
Dependencies are inferred from the claim text.