Hydraulic steering unit and hydraulic steering system

Patent metadata

Field	Value
Publication number	US-9926003-B2
Application number	US-201615147078-A
Country	US
Kind code	B2
Filing date	May 5, 2016
Priority date	May 13, 2015
Publication date	Mar 27, 2018
Grant date	Mar 27, 2018

Abstract

A hydraulic steering unit ( 3 ) is disclosed comprising a working port arrangement (L, R) having two working ports (L, R), a supply port arrangement having a high pressure port (P) and a low pressure port (T), a main flow path ( 7 ) having a main bleed (A 1 ) and a metering device ( 8 ) and being arranged between said high pressure port (P) and said working port arrangement (L, R), an amplification flow path ( 9 ) having an amplification bleed (Au) and being arranged between said high pressure port (P) and said working port arrangement (L, R), said main bleed (A 1 ) and said amplification bleed (Au) being controlled together by means of a steering handle ( 6 ) and being closed in neutral position of said steering handle ( 6 ), and a drain bleed (Ad) which is open in neutral position of said steering handle ( 6 ), said drain bleed (Ad) connecting a point ( 11 ) upstream said main bleed (A 1 ) and said amplification bleed (Au) to said low pressure port (T).

First claim

What is claimed is:

1. A hydraulic steering unit comprising a working port arrangement (L, R) having two working ports (L, R), a supply port arrangement having a high pressure port (P) and a low pressure port (T), a main flow path having a main bleed (A 1 ) and a metering device and being arranged between said high pressure port (P) and said working port arrangement (L, R), an amplification flow path having an amplification bleed (Au) and being arranged between said high pressure port (P) and said working port arrangement (L, R), said main bleed (A 1 ) and said amplification bleed (Au) being controlled together by means of a steering handle and being closed in neutral position of said steering handle, and a drain bleed (Ad) which is open in neutral position of said steering handle, said drain bleed (Ad) connecting a point upstream said main bleed (A 1 ) and said amplification bleed (Au) to said low pressure port (T), wherein a connection of said drain bleed (Ad) to said main flow path is upstream from said main bleed (A 1 ) and said amplification bleed (Au).

2. The hydraulic steering unit according to claim 1 , wherein said drain bleed (Ad) is fully closed, when said amplification bleed (Au) is fully open.

3. The hydraulic steering unit according to claim 1 , wherein a torque compensator is provided establishing a pressure differential over said amplification flow path to be the same as a pressure differential over said main (A 1 , A 2 , A 3 ).

4. The hydraulic steering unit according to claim 3 said torque compensator is formed by an adjustable flow resistance in said amplification flow path.

5. The hydraulic steering unit according to claim 4 , wherein said adjustable flow resistance is adjusted by a pressure in said main flow path.

6. The hydraulic steering unit according to claim 3 , wherein said torque compensator comprises a check valve opening in a direction towards a point downstream said metering device.

7. The hydraulic steering unit according to claim 1 , wherein an emergency check valve is arranged parallel to said drain bleed (Ad) opening to said point upstream said main bleed (A 1 ) and said amplification bleed (Au).

8. A hydraulic steering system comprising a steering motor, said hydraulic steering unit according to claim 1 , and a pump, wherein said hydraulic steering unit is directly connected to said pump.

9. The hydraulic steering system according to claim 8 , wherein said pump is a fixed displacement pump.

10. The hydraulic steering unit according to claim 2 , wherein a torque compensator is provided establishing a pressure differential over said amplification flow path to be the same as a pressure differential over said main (A 1 , A 2 , A 3 ).

11. The hydraulic steering unit according to claim 4 , wherein said torque compensator comprises a check valve opening in a direction towards a point downstream said metering device.

12. The hydraulic steering unit according to claim 5 , wherein said torque compensator comprises a check valve opening in a direction towards a point downstream said metering device.

13. The hydraulic steering unit according to claim 2 , wherein an emergency check valve is arranged parallel to said drain bleed (Ad) opening to said point upstream said main bleed (A 1 ) and said amplification bleed (Au).

14. The hydraulic steering unit according to claim 3 , wherein an emergency check valve is arranged parallel to said drain bleed (Ad) opening to said point upstream said main bleed (A 1 ) and said amplification bleed (Au).

15. The hydraulic steering unit according to claim 4 , wherein an emergency check valve is arranged parallel to said drain bleed (Ad) opening to said point upstream said main bleed (A 1 ) and said amplification bleed (Au).

16. Hydraulic steering unit according to claim 5 , wherein an emergency check valve is arranged parallel to said drain bleed (Ad) opening to said point upstream said main bleed (A 1 ) and said amplification bleed (Au).

17. The hydraulic steering unit according to claim 6 , wherein an emergency check valve is arranged parallel to said drain bleed (Ad) opening to said point upstream said main bleed (A 1 ) and said amplification bleed (Au).

18. A hydraulic steering system comprising a steering motor, said hydraulic steering unit according to claim 2 , and a pump, wherein said hydraulic steering unit is directly connected to said pump.

19. A hydraulic steering system comprising a steering motor, said hydraulic steering unit according to claim 3 , and a pump, wherein said hydraulic steering unit is directly connected to said pump.

20. A hydraulic steering system comprising a steering motor, said hydraulic steering unit according to claim 4 , and a pump, wherein said hydraulic steering unit is directly connected to said pump.

Assignees

• Danfoss Power Solutions Aps

Inventors

• Porskrog Bendt
• Olesen Casper Mikael
• Rahimzai Abdul Karim

Classifications

• B62D5/093 Primary

  Telemotor driven by steering wheel movement (hydraulic steering gear B62D3/14) · CPC title

• B62D5/18

  characterised by power transmitting means · CPC title

• B62D5/065

  characterised by specially adapted means for varying pressurised fluid supply based on need, e.g. on-demand, variable assist · CPC title

• B62D5/12

  Piston and cylinder · CPC title

• B62D5/062 Primary

  Details, component parts · CPC title