Motor cooling via hydraulic fluid

Abstract

The hydraulic system according to the invention comprises a hydraulic circuit with a low-pressure region and a high-pressure region; a volume- and/or speed-variable hydraulic machine, which is driven by a first electric motor and has an inlet and an outlet and provides a volume flow of a hydraulic fluid in the high-pressure region of the hydraulic circuit. The hydraulic system according to the invention further comprises at least one movable shaft, which is arranged in the high-pressure region of the hydraulic circuit; at least one valve, which separates the high-pressure region from the low-pressure region; and at least one hydraulic fluid container, which is hydraulically connected to the low-pressure region of the hydraulic circuit. The hydraulic system according to the invention also has a discharge line, which discharges hydraulic fluid from the leakage of the hydraulic machine, and a cooling line for transporting the hydraulic fluid in order to cool the electric motor, the discharge line and the cooling line being fluidically connected to at least one of the hydraulic fluid containers.

Claims

1. A hydraulic system, comprising: a hydraulic circuit, wherein the hydraulic circuit has a low-pressure region and a high-pressure region; a volume-variable and/or speed-variable hydraulic machine, which is driven by a first electric motor and has a first inlet and an outlet for providing a volume flow of a hydraulic fluid in the high-pressure region of the hydraulic circuit; at least one movable shaft, wherein the shaft is arranged in the high-pressure region of the hydraulic circuit; at least one valve which separates the high-pressure region from the low-pressure region; at least one hydraulic fluid container, which is hydraulically connected to the low-pressure region of the hydraulic circuit; a discharge line, which discharges from the hydraulic machine hydraulic fluid from leakage of the hydraulic machine; a cooling line for transporting the hydraulic fluid for cooling the electric motor; the discharge line and the cooling line fluidically connected to the at least one hydraulic fluid container; the hydraulic machine having a second inlet, which is hydraulically connected to the hydraulic circuit in the low-pressure region; and the second inlet connected to the leakage and to the discharge line via a housing of the hydraulic machine.

2. The hydraulic system according to claim 1, wherein the discharge line and the cooling line are fluidically connected in series or in parallel to the at least one hydraulic fluid container.

3. The hydraulic system according to claim 1, wherein the at least one valve comprises a check valve.

4. The hydraulic system according to claim 3, wherein the check valve comprises a controlled check valve.

5. The hydraulic system according to claim 1, wherein the cooling line and the second inlet are hydraulically connected to the hydraulic circuit in the low-pressure region.

6. The hydraulic system according to claim 1, wherein, at the inlet of the discharge line and/or of the cooling line, a second volume-variable and/or speed-variable hydraulic machine driven by an electric motor is arranged.

7. The hydraulic system according to claim 6, wherein a restrictor is arranged at the inlet of the discharge line and/or of the cooling line.

8. The hydraulic system according to claim 1, wherein the at least one hydraulic fluid container is arranged in the low-pressure region.

9. The hydraulic system according to claim 8, wherein the at least one hydraulic fluid container is a closed container.

10. The hydraulic system according to claim 9, wherein the closed container comprises a pressure accumulator.

11. The hydraulic system according to claim 8, comprising a second hydraulic fluid container arranged in the low-pressure region.

12. The hydraulic system according to claim 11, wherein the first hydraulic fluid container is a closed container and the second hydraulic fluid container is a non-pressurized container.

13. The hydraulic system according to claim 12, wherein the closed container is a pressure accumulator and the non-pressurized container is an open container.

14. The hydraulic system according to claim 11, wherein a second hydraulic machine is arranged between the low-pressure region of the hydraulic circuit and the second hydraulic fluid container.

15. The hydraulic system according to claim 11, wherein the discharge line and the cooling line are fluidically connected to the second hydraulic fluid container.

16. The hydraulic system according to claim 11, wherein the inlet of the discharge line and/or of the cooling line is fluidically connected to the second hydraulic fluid container.

17. The hydraulic system according to claim 1, wherein a cooler is arranged in the low-pressure region, at the second inlet, at the discharge line, at the cooling line, or at the at least one hydraulic fluid container.

18. A method for using the hydraulic system of claim 1, wherein the hydraulic fluid from the leakage of the hydraulic machine is used to cool the electric motor.

Description

(1) The following are shown:

(2) FIG. 1: a schematic representation of a system according to the invention;

(3) FIG. 2: a schematic further exemplary embodiment of the system according to the invention;

(4) FIG. 3: another exemplary embodiment of the hydraulic system, with a discharge line and cooling line arranged in parallel;

(5) FIG. 4: an embodiment of the hydraulic system from FIG. 1, comprising a further hydraulic fluid container;

(6) FIG. 5: a schematic further exemplary embodiment of the system according to the invention from FIG. 4;

(7) FIG. 6: a schematic further exemplary embodiment of the system according to the invention from FIG. 4;

(8) FIG. 7: yet another embodiment of the hydraulic system according to the invention.

(9) FIG. 1 shows an exemplary embodiment according to the invention of the hydraulic system 1. As can be seen from the figure, the hydraulic system can be divided into two regions: a low-pressure region 2, in which the hydraulic fluid has a low pressure—in particular, a pressure between ambient pressure and 30 bar—and a high-pressure region 4, in which the hydraulic fluid has a high pressure—in particular, above 30 bar—which is used to move a shaft 20 arranged in the hydraulic system and connected to the high-pressure region 4 of the hydraulic system 1.

(10) The hydraulic system 1 has a first electric motor 10 and a hydraulic machine 11 driven by the electric motor 10. This is arranged in the high-pressure region 4 and serves to provide a volume flow of the hydraulic fluid in the shaft 20. The shaft is shown as a double-acting hydraulic cylinder with two chambers. The hydraulic machine has two outputs or inputs, each of which is connected to a chamber of the shaft 20. The hydraulic machine can thus convey hydraulic fluid from one chamber of the shaft 20 into the other chamber of the shaft 20, whereby a movement of the shaft 20 is provided.

(11) The high-pressure region 4 and the low-pressure region 2 are separated from one another by means of unlockable check valves 30.

(12) Due to the continuous operation of the hydraulic machine 11, leakages occur at the hydraulic machine 11, as a result of which the volume of hydraulic fluid in the high-pressure region 4 drops. By precisely adjusting the spring strength in the check valves 30 or by electrical unlocking, the missing volume of hydraulic fluid can be conducted from the low-pressure region 2 into the high-pressure region 4.

(13) According to FIG. 1, a hydraulic fluid container 50, which is designed as a pressure accumulator 50, is hydraulically connected to the low-pressure region 2 of the hydraulic system 1.

(14) As shown in FIG. 1, the hydraulic system 1 comprises a discharge line 62 which is connected to the leakage or to the leakage collection area of the hydraulic machine in such a way that the leakage fluid can be fed back into the low-pressure region through the discharge line.

(15) In this respect, according to this exemplary embodiment according to the invention, the discharge line 62 has been connected to the cooling line 64 of the electric motor so that the leakage fluid is used as coolant for the electric motor 11. In this example, the discharge line and the cooling line are thus arranged in series. The cooling line 64 is in turn fluidically connected to the low-pressure region 2 and, in particular, fluidically connected to the hydraulic fluid container 50. The leakage fluid is thus used for cooling and subsequently fed back into the system.

(16) FIG. 2 shows an alternative exemplary embodiment of the hydraulic system 1 according to the invention from FIG. 1.

(17) While the general design of the embodiment according to FIG. 2 corresponds to the design of FIG. 1, the hydraulic system of FIG. 1 furthermore comprises an inlet 66 and a second electric motor 100 with a second hydraulic machine 110 driven by the electric motor.

(18) The inlet 66 is connected to the leakage area via the housing of the hydraulic machine 11, which is hydraulically connected in series to the discharge line 62 as in FIG. 1.

(19) The inlet 66 is furthermore fluidically connected to the low-pressure region 2 via the second hydraulic machine 110. An improved control of the volume flow through the discharge line and/or the cooling line can thus be achieved by means of the hydraulic machine 110.

(20) FIG. 3 shows another exemplary alternative embodiment according to the invention of FIG. 2. In this exemplary embodiment, the discharge line 62 and the cooling line 64 are arranged in parallel so that both lines are hydraulically connected to the low-pressure region 2. By contrast, the inlet 66 is hydraulically connected, via a restrictor 70b, to the cooling line and thus to the housing of the electric motor 10, and, via a further restrictor 70a, to the discharge line. The inlet 66 is connected to the low-pressure region 2 via the hydraulic machine 110. The restrictors 70a and 70b thus serve to regulate the volume flow in the discharge line 62 and/or the cooling line 64.

(21) FIG. 4 shows another exemplary embodiment according to the invention of the hydraulic system 1 from FIG. 1.

(22) As can be seen from FIG. 4, the following exemplary embodiment according to the invention has a further hydraulic fluid container 52 which, in contrast to the first hydraulic fluid container 50, is an open tank. The open tank 52 is also fluidically connected to the low-pressure region 2.

(23) According to this exemplary embodiment according to the invention, the cooling line 64 and the discharge line 62 are connected to one another in series. Furthermore, they are fluidically connected to the hydraulic fluid container 52 so that hydraulic fluid flows from the leakage area of the hydraulic machine 11, through the cooling line of the electric motor 10, and then into the hydraulic fluid container 52.

(24) Furthermore, a further hydraulic machine 210 driven by an electric motor 200 is arranged between the hydraulic fluid container 50 and the low-pressure region 2. The hydraulic machine provides a fluid flow from the further hydraulic fluid container 52 into the low-pressure region 2.

(25) The further structure of the exemplary embodiment according to the invention from FIG. 4, and, in particular, the structure of the high-pressure region, corresponds to the exemplary embodiment of the hydraulic system 1 from FIG. 1.

(26) FIG. 5 shows yet another exemplary embodiment according to the invention of the hydraulic system 1.

(27) As can be seen from the figure, a second hydraulic fluid container 52 is also fluidically connected here to the low-pressure region of the hydraulic system via an additional hydraulic machine 210. Furthermore, the discharge line 62 and the cooling line 64 are fluidically connected in series and to the hydraulic fluid container 52.

(28) In contrast to FIG. 4, in this system of FIG. 5, an inlet 66 is connected to the discharge line 62 of the hydraulic machine 11. This inlet is furthermore hydraulically connected to the low-pressure region 2 of the hydraulic system 1. A restrictor 70 is arranged in the inlet and regulates or controls the flow of the hydraulic fluid into the discharge line 52.

(29) FIG. 6 is similar to FIG. 5, wherein, in this exemplary embodiment according to the invention, the discharge line and the cooling line are fluidically connected in parallel to a line 68 which itself is hydraulically connected to the second hydraulic fluid container 52.

(30) Furthermore, the inlet 66 is fluidically connected to the discharge line 62 via a restrictor 70a and to the cooling line 64 via a second restrictor 70b. Furthermore, the inlet is fluidically connected to the low-pressure region 2 of the hydraulic system 1.

(31) FIG. 7 shows another exemplary embodiment according to the invention of the hydraulic system 1.

(32) As already shown in the previous embodiments, a further hydraulic fluid container 52, with an open design, is arranged in the low-pressure region 2 of the hydraulic circuit 1 via a hydraulic machine 210.

(33) The discharge line 62 and the cooling line 62 are arranged in series and are fluidically connected to the hydraulic fluid container 52 via a line 68. An inlet 66 is fluidically connected to the cooling line 64 at one end and to the hydraulic fluid container 52 at the other end via a further hydraulic machine 310, which is driven by a further, third electric motor 300. The hydraulic fluid required for cooling is thus still obtained from the low-pressure region 2. 1 Hydraulic system 2 Low-pressure region 4 High-pressure region 10 First electric motor 11 Hydraulic machine 20 Shaft 30 Check valve 50 First hydraulic fluid container 52 Second hydraulic fluid container 62 Discharge line 64 Cooling line 66, 66a, 66b Inlet 68 Line 70, 70a, 70b Restrictor 100 Second electric motor 110 Second hydraulic machine 200 Electric motor 210 Hydraulic machine