CHARGED HYDRAULIC SYSTEM

• US 20090113888A1
• Filed: 10/30/2008
• Published: 05/07/2009
• Est. Priority Date: 11/01/2007
• Status: Active Grant

• Current Assignee: Danfoss Power Solutions ApS (Danfoss A/S)
• Original Assignee: Sauer-Danfoss Aps (Bitten Og Mads Clausens Fond)
• Inventors: Kuttler, Onno, Wadsley, Luke, Joly, Pierre, Gandrud, Michael D.
• Granted Patent: US 9,188,114 B2
• Time in Patent Office: Days
• US Class Current: 60/486
• CPC Class Codes: F04B 1/145 Housings
• CPC Class Codes: F04B 23/04 Combinations of two or more pumps
• CPC Class Codes: F04B 23/06 the pumps being all of reciprocating positive-displacement type
• CPC Class Codes: F04B 23/08 the pumps being of different types
• CPC Class Codes: F04B 23/106 being an axial piston pump
• CPC Class Codes: F04B 23/14 at least one pump being of the non-positive-displacement type
• CPC Class Codes: F04B 49/243 by keeping open the inlet valve
• CPC Class Codes: F04B 7/0076 the members being actuated by electro-magnetic means
• CPC Class Codes: F15B 2211/20592 Combinations of pumps for supplying high and low pressure

Abstract

In open-circuit hydraulic systems (1), the cross-sections of the supply lines (6) and input valves of the hydraulic pump (3) have to be large, so that sufficient flow flux can be provided. This hinders a reduction of the size of the pump and the whole hydraulic system. It is suggested that the supply flow (7) of a hydraulic pump (3) is charged by a second, charging pump (2), to a mid-pressure level (7). The cross-sections of the supply flow areas can thus be decreased.

Claims

1. A hydraulic system with at least one hydraulic high pressure pump and at least one hydraulic charging pump, wherein the output hydraulic fluid flow of said hydraulic charging pump is used as the input hydraulic fluid flow of said hydraulic high pressure pump, wherein the maximum flow of said output fluid flow of said hydraulic charging pump is at least 50 percent of the maximum flow rate of said input fluid flow of said hydraulic high pressure pump.

2. The hydraulic system according to claim 1, wherein the maximum flow rate of said output fluid flow of the hydraulic charging pump is at least essentially the same as or higher than the maximum flow rate of said input fluid flow of said hydraulic high pressure pump.

3. The hydraulic system according to claim 1, wherein the output pressure of said hydraulic charging pump is 0.3 to 10 bars, preferably 0.5 to 7 bars, more preferably 1 to 5 bars, even more preferably 1.5 to 3 bars, most preferably 2 to 2.5 bars.

4. The hydraulic system according to claim 1, wherein a plurality of hydraulic high pressure pumps and/or a plurality of hydraulic charging pumps is provided.

5. The hydraulic system according to claim 1, wherein at least one hydraulic high pressure pump is a synthetically commutated hydraulic pump.

6. The hydraulic system according claim 1, wherein at least two hydraulic pumps are driven by the same power source.

7. The hydraulic system according to claim 1, wherein at least one hydraulic charging pump is of a self-delimiting type.

8. The hydraulic system according to claim 1, wherein at least one hydraulic charging pump is of a fluid jet pump type.

9. The hydraulic system according to claim 1, wherein at least one hydraulic pump is designed as a two-stage pump.

10. The hydraulic system according to claim 1, wherein the output fluid flow of said hydraulic high pressure pump, after passing a hydraulic consumer, is joined with the output fluid flow of said hydraulic charging pump and used as the input fluid flow of said hydraulic high pressure pump.

11. The hydraulic system according to claim 1, wherein the output fluid flow of at least one hydraulic charging pump is used at least partially for a hydraulic consumer.

12. The hydraulic system according to claim 1, wherein at least one hydraulic consumer can be alternatively fed by the output flow of at least one hydraulic high pressure pump and/or the output fluid flow of at least one hydraulic charging pump.

16. The hydraulic system according to the generic part of claim 1, wherein the output hydraulic fluid flow of the hydraulic charging pump is at least partially going through a hydraulic consumer, before being used as the input fluid flow of said hydraulic high pressure pump.

13. A hydraulic pump, comprising at least a first, charging stage and a second, high pressure stage.

14. The hydraulic pump according to claim 13, wherein said charging stage comprises an impeller device and/or a fluid jet device.

15. The hydraulic pump according to claim 13, wherein both stages are driven by a common driving shaft, and are preferably mounted on said driving shaft.