System and method for operating a variable displacement hydraulic pump
First Claim
Patent Images
1. A machine including an engine and a hydraulic system having a reservoir connected to a drain passage, the hydraulic system including an implement valve disposed to operate an implement, the implement valve providing fluid at a load sensing pressure within a control conduit during operation, the machine comprising:
- a manual control device adapted to provide a request signal;
a variable displacement pump operably connected to the engine, disposed to receive a torque limit from the engine, and associated with the hydraulic system, the variable displacement pump providing an operating fluid flow at a supply pressure to the hydraulic system, the operating fluid flow being correlated to a load during operation;
a control valve fluidly connected to the control conduit and operating to adjust a displacement setting of the variable displacement pump based on a pressure difference between a reference pressure and the supply pressure;
an electro-hydraulic relief valve in fluid communication with the control conduit and the drain passage, the electro-hydraulic relief valve disposed to selectively vent fluid from the control conduit into the drain passage in response to a command signal;
an electronic controller associated with the implement valve, the electro-hydraulic relief valve and the engine, and disposed to receive at least one signal that is indicative of at least one machine operating parameter, the electronic controller being further disposed to calculate the reference pressure and provide the command signal to the electro-hydraulic relief valve based on the reference pressure;
wherein the electronic controller is further disposed to receive a pressure signal that is indicative of a pressure of fluid at an outlet of the variable displacement pump, wherein the reference pressure is at least partially based on a derivative of the pressure signal.
1 Assignment
0 Petitions
Accused Products
Abstract
A control for a variable displacement pump disposed in a hydraulic system obtains a requested signal from a manual control device and provides a command signal to a valve operating to adjust a displacement setting of the variable displacement pump. The control provides the command signal based on the requested signal, and scales the requested signal based on a sensed or calculated load of the system.
49 Citations
17 Claims
-
1. A machine including an engine and a hydraulic system having a reservoir connected to a drain passage, the hydraulic system including an implement valve disposed to operate an implement, the implement valve providing fluid at a load sensing pressure within a control conduit during operation, the machine comprising:
-
a manual control device adapted to provide a request signal; a variable displacement pump operably connected to the engine, disposed to receive a torque limit from the engine, and associated with the hydraulic system, the variable displacement pump providing an operating fluid flow at a supply pressure to the hydraulic system, the operating fluid flow being correlated to a load during operation; a control valve fluidly connected to the control conduit and operating to adjust a displacement setting of the variable displacement pump based on a pressure difference between a reference pressure and the supply pressure; an electro-hydraulic relief valve in fluid communication with the control conduit and the drain passage, the electro-hydraulic relief valve disposed to selectively vent fluid from the control conduit into the drain passage in response to a command signal; an electronic controller associated with the implement valve, the electro-hydraulic relief valve and the engine, and disposed to receive at least one signal that is indicative of at least one machine operating parameter, the electronic controller being further disposed to calculate the reference pressure and provide the command signal to the electro-hydraulic relief valve based on the reference pressure; wherein the electronic controller is further disposed to receive a pressure signal that is indicative of a pressure of fluid at an outlet of the variable displacement pump, wherein the reference pressure is at least partially based on a derivative of the pressure signal.
-
-
2. A machine including an engine and a hydraulic system having a reservoir connected to a drain passage, the hydraulic system including an implement valve disposed to operate an implement, the implement valve providing fluid at a load sensing pressure within a control conduit during operation, the machine comprising:
-
a manual control device adapted to provide a request signal; a variable displacement pump operably connected to the engine, disposed to receive a torque limit from the engine, and associated with the hydraulic system, the variable displacement pump providing an operating fluid flow at a supply pressure to the hydraulic system, the operating fluid flow being correlated to a load during operation; a control valve fluidly connected to the control conduit and operating to adjust a displacement setting of the variable displacement pump based on a pressure difference between a reference pressure and the supply pressure; an electro-hydraulic relief valve in fluid communication with the control conduit and the drain passage, the electro-hydraulic relief valve disposed to selectively vent fluid from the control conduit into the drain passage in response to a command signal; an electronic controller associated with the implement valve, the electro-hydraulic relief valve and the engine, and disposed to receive at least one signal that is indicative of at least one machine operating parameter, the electronic controller being further disposed to calculate the reference pressure and provide the command signal to the electro-hydraulic relief valve based on the reference pressure; wherein the electronic controller is further disposed to receive an estimated torque signal and a torque limit, to calculate an error value between the estimated torque signal and the torque limit, and to integrate the error value to provide an integral term that represents a portion of the command pressure. - View Dependent Claims (3, 4)
-
-
5. A machine including an engine and a hydraulic system having a reservoir connected to a drain passage, the hydraulic system including an implement valve disposed to operate an implement, the implement valve providing fluid at a load sensing pressure within a control conduit during operation, the machine comprising:
-
a manual control device adapted to provide a requested signal; a variable displacement pump operably connected to the engine, disposed to receive a torque limit from the engine, and associated with the hydraulic system, the variable displacement pump providing an operating fluid flow at a supply pressure to the hydraulic system via a supply conduit, the operating fluid flow being correlated to a load during operation; a control valve fluidly connected to the control conduit and operating to adjust a displacement setting of the variable displacement pump based on a pressure difference between a reference pressure and the supply pressure; an electronic pressure reducing valve (EPRV) in fluid communication with the control conduit and the supply conduit the EPRV disposed to selectively vent fluid from the supply conduit into a reduced pressure conduit in response to a command signal; a low pressure resolver having a first inlet in fluid communication with the reduced pressure conduit, a second inlet in fluid communication with the control conduit, and an outlet in fluid communication with the control valve, the low pressure resolver disposed to fluidly connect the outlet with one of the first inlet and the second inlet that is disposed at a lowest pressure therebetween; an electronic controller associated with the implement valve, the EPRV and the engine, and disposed to receive at least one signal that is indicative of at least one machine operating parameter, the electronic controller being further disposed to calculate the reference pressure and provide the command signal to the EPRV based on the reference pressure. - View Dependent Claims (6, 7, 8, 9, 10)
-
-
11. A method for de-rating a hydraulic system operating in a machine by limiting a flow of fluid through a main valve, the method comprising:
-
determining a loading of the hydraulic system; providing a scale factor for de-rating the hydraulic system based on the loading; applying the scale factor to a requested signal to generate a commanded signal; and reducing a load consumption of the hydraulic system by operating the main valve in response to the commanded signal; wherein providing the scale factor further includes determining an error signal based on the loading and a torque limit. - View Dependent Claims (12, 13, 14, 15, 16, 17)
-
Specification