Control arrangement of a hydraulic system and a method for controlling a hydraulic system

Patent metadata

Field	Value
Publication number	US-11149758-B2
Application number	US-201414785956-A
Country	US
Kind code	B2
Filing date	Mar 31, 2014
Priority date	Jun 4, 2013
Publication date	Oct 19, 2021
Grant date	Oct 19, 2021

Abstract

A control arrangement ( 5 ) of a hydraulic system ( 1 ) is provided, said control arrangement ( 5 ) comprising a supply port arrangement having a high pressure port ( 6 ) and a low pressure port ( 7 ), a working port arrangement having two working ports ( 8, 9 ), a first valve ( 10 ) arranged between said high pressure port ( 6 ) and said working port arrangement ( 8, 9 ), a second valve ( 11 ) arranged between said low pressure port ( 7 ) and said working port arrangement ( 8, 9 ). Such a control arrangement should enhance the control of a hydraulic system. To this end a controller ( 16 ) is provided for controlling said first valve ( 10 ) and said second valve ( 11 ), said controller ( 16 ) has an input connection ( 17 ) for receiving a signal of an operator input device and on the basis of said signal said controller at least initially calculates an unbalance between a first flow demand for said first valve ( 10 ) and a second flow demand for said second valve ( 11 ), and adjusts said first valve ( 10 ) according to said first flow demand and said second valve ( 11 ) according to said second flow demand.

First claim

What is claimed is:

1. A method for controlling a hydraulic system comprising a supply port arrangement having a high pressure port and a low pressure port, a working port arrangement connected to an actuator having two working ports, a first valve arranged between said high pressure port and said working port arrangement, and a second valve arranged between said low pressure port and said working port arrangement, the method comprising generating an input signal for said hydraulic system, wherein a first flow demand for the first valve and a second flow demand for the second valve are calculated separately to create at least initially an unbalance between said first flow demand and said second flow demand, each flow demand being a quantity representing a flow to pass through the first valve or the second valve respectively, wherein the unbalance between the first flow demand and the second flow demand indicates that the first flow demand and the second flow demand do not correspond to a cylinder ratio of the actuator.

2. The method according to claim 1 , wherein in case of a positive load, the first valve determines the velocity of an actuator connected to said working port arrangement and a back pressure is automatically adjusted to its minimum level.

3. The method according to claim 1 , wherein, in case of a negative load, the second valve determines the velocity of an actuator connected to said working port arrangement and the first valve determines an anti-cavitation pressure.

4. A control arrangement of a hydraulic system comprising:
a supply port arrangement having a high pressure port and a low pressure port;
a working port arrangement connected to an actuator having a first working port and a second working port;
a first valve arranged between said high pressure port and said working port arrangement;
a second valve arranged between said low pressure port and said working port arrangement; and
a controller for controlling said first valve and said second valve;
wherein fluid flowing from said high pressure port to said first working port or said second working port is meter-in flow;
wherein fluid flowing from said first working port or said second working port to said low pressure port is meter-out flow;
wherein said controller has an input connection for receiving a signal of an operator input device and on the basis of said signal said controller controls said first valve and said second valve such that the ratio of a quantity the meter-out flow to a quantity of the meter-in flow is greater than a cylinder ratio of said actuator; and
wherein said cylinder ratio of said actuator is an out pressure area to an in pressure area, said out pressure area being fluidly connected with said low pressure port and said in pressure area being fluidly connected with said high pressure port.

5. The control arrangement according to claim 4 , wherein, depending on a load condition at the working port arrangement, said controller corrects said meter-in flow and/or said meter-out flow.

6. The control arrangement according to claim 5 , further comprising a first pressure sensor (P 2 ) connected to the first working port, a second pressure sensor (P 1 ) connected to the second working port, a third pressure sensor (PP) connected to the high pressure port and a fourth pressure sensor (PT) connected to the low pressure port, wherein said controller is configured to detect a first pressure drop over said first valve due to the load condition, based on a difference between the first pressure sensor (P 2 ) and the third pressure sensor (PP) or based on a difference between the second pressure sensor (P 1 ) and the third pressure sensor (PP), and wherein said controller is configured to detect a second pressure drop over said second valve due to the load condition, based on a difference between the second pressure sensor (P 1 ) and the fourth pressure sensor (PT) or based on a difference between the first pressure sensor (P 2 ) and the fourth pressure sensor (PT).

7. The control arrangement according to claim 5 , wherein said first valve and/or said second valve are spool valves.

8. The control arrangement according to claim 5 , wherein, in case of a positive load, the first valve determines the velocity of the actuator connected to said working port arrangement and a back pressure is automatically adjusted to its minimum level.

9. The control arrangement according to claim 4 , further comprising a first pressure sensor (P 2 ) connected to the first working port, a second pressure sensor (P 1 ) connected to the second working port, a third pressure sensor (PP) connected to the high pressure port and a fourth pressure sensor (PT) connected to the low pressure port, wherein said controller is configured to detect a first pressure drop over said first valve, based on a difference between the first pressure sensor (P 2 ) and the third pressure sensor (PP) or based on a difference between the second pressure sensor (P 1 ) and the third pressure sensor (PP), and wherein said controller is configured to detect a second pressure drop over said second valve, based on a difference between the second pressure sensor (P 1 ) and the fourth pressure sensor (PT) or based on a difference between the first pressure sensor (P 2 ) and the fourth pressure sensor (PT).

10. The control arrangement according to claim 9 , wherein said first valve and/or said second valve are spool valves.

11. The control arrangement according to claim 4 , wherein said first valve and said second valve each comprise means for indicating an opening degree, said means being connected to said controller.

12. The control arrangement according to claim 11 , wherein said first valve and/or said second valve are spool valves.

13. The control arrangement according to claim 4 , wherein said first valve and/or said second valve are spool valves.

14. The control arrangement according to claim 4 , wherein, in case of a positive load, the first valve determines the velocity of the actuator connected to said working port arrangement and a back pressure is automatically adjusted to its minimum level.

15. The control arrangement according to claim 4 , wherein, in case of a negative load, the second valve determines the velocity of the actuator connected to said working port arrangement and the first valve determines an anti-cavitation pressure.

Assignees

• Danfoss Power Solutions Aps

Inventors

• Callesen Frede
• Wroblewski Dirk

Classifications

• F15B21/087 Primary

  Control strategy, e.g. with block diagram · CPC title

• F15B2211/30565

  having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve · CPC title

• F15B2211/6346

  representing a state of input means, e.g. joystick position · CPC title

• F15B2211/6654

  Flow rate control · CPC title

• F15B11/08

  with only one servomotor · CPC title