EP3224484B1 - Cooling device for a hydraulic assembly and use of a cooling device - Google Patents

Description

The invention is based on a cooling device for a hydraulic unit for cooling a container for hydraulic oil of the hydraulic unit. The invention also relates to a use of the cooling device.

It is known from the prior art, for example, that pressure medium or hydraulic oil is conveyed from a container via a hydraulic pump, such as an external gear pump, which can be driven by a variable-speed motor. On the output side of the pump, the pressure medium can be branched off via a throttle, which can also be used to set a minimum speed of the pump. Pressure medium branched off via the throttle can emit heat to an environment via a radiator that is cooled by air from a fan. In addition, a leak from the pump can be fed to the radiator. The disadvantage here is that the throttle leads to hydraulic losses, which in turn lead to waste heat. A size of a volume flow through the radiator is also disadvantageously dependent on a system pressure on the output side of the pump, which is why there is no constant cooling capacity of the pressure medium. In addition, the pressure medium can only be cooled by the radiator while the pump is in operation.

Furthermore, it is known from the prior art to convey pressure medium from the container via two pumps (double pumps) which can be driven jointly by a variable-speed motor. One of the pumps can convey a volume flow for a cooling circuit, which can optionally have a filter. The disadvantage here is that an additional pump is required for cooling, which results in a higher outlay in terms of device technology and thus in particular also in higher costs Manufacturing costs leads. Furthermore, the additional pump is an additional sound source. The expense of piping is also comparatively high, which also increases the risk of leakage. Furthermore, the probability of failure can increase through the use of the double pump, since experience has shown that the pump is the component in a hydraulic system that is prone to wear. In addition, the additional pump leads to hydraulic losses and thus to additional heat load. Since the pumps are coupled to one another, the volume flow of the cooling circuit is dependent on the volume flow of a primary circuit of the first pump. In addition, there is also disadvantageous cooling only during operation of the pumps.

From the pamphlets JP S58 196301 A and JP S61 116112 A cooling devices for containers are known which have heat pipes in the form of heat pipes.

So reveals the JP S61 116112 A a cooling device with a large number of parallel bundled heat pipes. The heat pipes have a heat absorption section in a tank and a cooling section protruding from the tank. Ribs are provided on both sections to improve heat transfer.

The US 2011/0303389 A1 discloses a fluid tank with passively acting cooling fins which protrude inside and outside the tank from a side wall, the outer cooling fins being arranged to be cooled by an air flow of a fan of an active acting heat exchanger, wherein a fluid flow from the heat exchanger into the fluid tank leads.

The JP S52 119117 U discloses a fluid tank with a cooling device comprising a plurality of heat pipes which extend through a wall or a lid of the tank, with fins being installed on the heat pipes inside and outside the lid.

The JP H06 18608 U discloses a cooling device with hollow tubes connecting two container sections, through which heat pipes extend concentrically in order to be flowed around along a longitudinal axis. It further discloses providing a channel in a bottom area of a tank so that a fluid introduced into the tank washes around bottom sections of a plurality of heat pipes one after the other. It also discloses a tank with heat pipes arranged in it and a baffle plate through which the heat pipes reach at a distance, so that a laminar flow is created along the heat pipes.

In contrast, the invention is based on the object of creating a cooling device for a hydraulic unit that can also cool pressure medium outside of operation of the hydraulic unit or while the hydraulic unit is at a standstill, has an improved degree of efficiency compared to the prior art and requires little space. Another object of the invention is to provide an advantageous use of a cooling device according to the invention.

The object with regard to the cooling device is achieved according to the features of claim 1 and with regard to the use according to the features of claim 14.

Other advantageous developments of the invention are the subject of further subclaims.

According to the invention, a cooling device for a hydraulic unit is provided. The cooling device here has a container or tank for a hydraulic oil of the hydraulic unit. The container has an inlet and an outlet, which can be designed as a return line and suction line. The cooling device has at least two heat pipes, preferably three heat pipes, each heat pipe being immersed with a pipe section in the container. It can thus dissipate heat from the hydraulic oil. This solution has the advantage that such a cooling device can also cool hydraulic oil while the hydraulic unit is at a standstill, in that heat is dissipated via the at least one heat pipe. In addition, the cooling device has an improved degree of efficiency compared to the prior art and requires less space.

The heat pipe is, for example, a heat pipe or a two-phase thermosiphon. The heat pipe has a refrigerant that evaporates at a point to be cooled, whereby heat is dissipated as heat of vaporization. The gaseous coolant can then distribute itself in the heat pipe and precipitate on a cooled section (heat sink) on an inner wall of the pipe. Due to the force of gravity or a capillary effect, the coolant can then flow back to the cooling point.

The heat pipes each protrude with a further pipe section from the container in order to dissipate the heat to the outside.

The heat pipes are arranged in the flow path of the hydraulic oil between the inlet and the outlet. The inlet, outlet and heat pipes are arranged approximately in a row. As a result of the arrangement of the heat pipes in the named flow path, the hydraulic oil flowing from the inlet to the outlet flows around this during operation of the hydraulic unit.

In a device-technically simple manner, the flow path can preferably extend approximately in one direction between the inlet and the outlet, whereby no or no major changes in direction of the flow path are provided and thus a simple geometric design, in particular of the container, is made possible and flow losses are minimized.

The heat pipes are arranged in such a way that, viewed in the direction of the flow path, they are not arranged one behind the other in series. Thus, the heat pipes do not shade each other, causing more heat from the hydraulic oil to the heat pipes can be performed. The two or more heat pipes are preferably arranged approximately transversely to the flow path, viewed in the direction of the flow path, or are provided in a common plane which is angled to the direction of the flow path. The heat pipes can preferably extend approximately parallel to one another. The heat pipes protruding from the container can also extend essentially in the same direction, this being about a vertical direction.

A cooling structure can be provided on the heat pipes for improved heat supply and / or heat dissipation. The cooling structure is preferably at least thermally connected to the heat pipe. It is conceivable that the cooling structure is also mechanically connected to the heat pipes or is designed in one piece with them. It is conceivable to provide a cooling structure inside the container and a cooling structure outside the container. The cooling structure has, for example, a plurality or multiplicity of lamellae which can be designed as a lamellae pack. For example, the fins extend approximately perpendicular to the at least one heat pipe. These can be arranged approximately parallel to one another. Two or more heat pipes can share a respective cooling structure.

A size of the cooling structure in the container corresponds approximately to a flow cross section of the flow path of the container or the cross section of the container in the flow direction. Thus, fins of the heat pipe or the heat pipes within the container can penetrate approximately the full cross section of the container. Due to the geometric arrangement of the inlet on one side of the plate pack and the outlet on the other side of the plate pack, a volume flow can be guided through the plate pack. This increases heat transfer from the hydraulic oil to the fins and thus in turn to the heat pipe or pipes.

The cooling structure can be provided on the tube section of the heat pipes provided inside the container. Additionally or alternatively, the cooling structure can be provided on the tube section of the heat pipes provided outside the container. The cooling structure can be designed in such a way that it promotes a degassing process for the hydraulic oil.

The heat pipes and / or the cooling structure can be cooled outside the container by forced convection, in particular by a fan. Alternatively or in addition, the heat pipes and / or the cooling structure outside the container can be cooled by a heat exchanger. A material flow (cooling water) can then flow through the heat exchanger, for example. The heat exchanger can thus have a cooling water circuit. Alternatively or additionally, the heat exchanger can also be thermally and / or mechanically (in particular directly) connected to a housing, in particular a machine housing, in particular the hydraulic unit, in order to give off heat to the housing.

A flow cross section of the flow path is advantageously reduced like a throttle in the area of the heat pipes and / or in the area of the cooling structure. This is advantageous if the heat pipes and / or the cooling structure (lamellar pack) do not completely penetrate the cross section of the container, so that the hydraulic oil can then be forced to the heat pipes and / or to the cooling structure. In addition, the throttle-like reduction in size can increase a flow rate of the hydraulic oil, which enables an improved flow around the heat pipes and / or the cooling structure.

At least the heat pipes and / or the cooling structure can be arranged approximately in the region of the narrowest cross section of the container.

The flow cross-section is reduced, for example, by a flow guide. This is preferably a ramp or a partition that reduces the flow cross-section. If a ramp is provided, it can be angled starting from a container bottom, in particular extending away in the direction of flow. The reduction in the flow cross section is preferably carried out continuously, as a result of which the flow properties of the hydraulic oil are improved.

In a further embodiment of the invention, the hydraulic oil can be conveyed from the outlet via a hydraulic machine which can be driven by a drive unit. The drive unit can have its own cooling device, which is also simple in terms of device technology is used to cool the heat pipes and / or the cooling structure. The cooling device of the drive unit is preferably a fan, the air flow of which is used for cooling. Thus, by geometrically arranging the lamella pack outside of the container behind the motor fan, the heat transfer to the environment can be increased by the air volume flow generated thereby.

The drive unit and the hydraulic machine can then advantageously form a motor-pump unit or a motor-pump group. An arrangement with the cooling device according to the invention and the motor-pump unit can then preferably be provided. The motor-pump unit is preferably arranged directly or adjacent to the at least one outer heat pipe and / or its outer cooling structure.

In addition to the heat pipes for the container, a further heat pipe can advantageously be provided for a further component of the hydraulic unit. The further heat pipe can then be arranged with at least one pipe section adjacent to the pipe section of the at least one heat pipe of the container. The heat pipes can then bundle both the heat of the container and the heat of a further component or further components, such as the drive unit or other “hotspots”. As a result, a temperature of the entire hydraulic unit can be kept constant and / or heat can be dissipated together. With this concept, the thermal energy can be bundled and used alternatively for further processes.

The heat pipes of the container and at least one further component are preferably cooled together.

As already explained above, the waste heat of at least one heat pipe of the container and / or the component can be provided for at least one further process.

The heat pipes for the container together with the cooling structure are preferably designed in such a way that an approximately constant temperature is provided on both heat absorption surfaces and heat emission surfaces. As a result, a temperature difference to the hydraulic oil or to the environment can be approximately the same over an entire area be great. As a result, the heat dissipation capacity is comparatively high for the same area, and the cooling device can be designed more compact.

In an advantageous use of the cooling device, it is provided that it is used for a hydraulic unit which has a comparatively low cooling requirement and can be a so-called "small unit". The hydraulic unit or the container of the hydraulic unit preferably has a cooling capacity of max. 1000 watts, preferably of max. 300 to 500 watts. When using the cooling device for small units, it is therefore advantageously possible to use products from the computer industry, since modern graphics cards, for example, have a similar cooling capacity. For example, heat pipes from the computer industry are technically well developed and usually inexpensive.

Other advantageous developments are the subject of further subclaims.

• Figur 1 in einer schematischen Darstellung eine Kühlvorrichtung gemäß einem ersten Ausführungsbeispiel,
• Figur 2 in einer schematischen Darstellung die Kühlvorrichtung gemäß einem zweiten Ausführungsbeispiel,
• Figur 3 in einer schematischen Darstellung die Kühlvorrichtung gemäß einem dritten Ausführungsbeil,
• Figur 4 in einer schematischen Darstellung die Kühlvorrichtung gemäß einem vierten Ausführungsbeispiel,
• Figur 5 in einer schematischen Darstellung die Kühlvorrichtung gemäß einem fünften Ausführungsbeispiel und
• Figur 6 in einer schematischen Darstellung eine Temperaturverteilung der Kühlvorrichtung.

Preferred embodiments of the invention are explained in more detail below with reference to drawings. Show it:

• Figure 1 in a schematic representation a cooling device according to a first embodiment,
• Figure 2 in a schematic representation the cooling device according to a second embodiment,
• Figure 3 in a schematic representation the cooling device according to a third exemplary embodiment,
• Figure 4 in a schematic representation the cooling device according to a fourth embodiment,
• Figure 5 in a schematic representation the cooling device according to a fifth embodiment and
• Figure 6 a schematic representation of a temperature distribution of the cooling device.

According to Figure 1 the cooling device 1 has a container 2 for hydraulic oil. Hydraulic oil 6 is fed to the container 2 from a hydraulic unit via an inlet 4 in the form of an inlet line. Hydraulic oil 10 is then led out of the container 2 via a drain 8 in the form of a drain line. According to the embodiment in Figure 1 are the Inlet 4 and outlet 8 are arranged approximately parallel to one another. The container 2 has an approximately cuboid design. Between the inlet 4 and the outlet 8, three heat pipes 12, 14 and 16 are provided. These are approximately rod-shaped and immersed into the container 2 with a pipe section 18 and protrude from the container 2 with a further pipe section 20. The heat pipes 12 to 16 extend approximately in a vertical direction and are arranged parallel to one another. The heat pipes 12 to 16 here extend approximately in a common plane. A cooling structure in the form of a laminated core 22 is arranged on the inner pipe sections 18 of the heat pipes 12 to 16. This is arranged together with the heat pipes 12 to 16 in the plane. The plate pack 22 has a plurality of plates extending approximately parallel to one another. The slats extend approximately in the horizontal direction.

A flow path 24 within the container 2 leads from the inlet 4 to the outlet 8 approximately in a single direction. The disk pack 22 is then arranged within the flow path 24. According to Figure 1 the plane in which the lamella pack 22 and the heat pipes 12 to 16 are arranged extends approximately transversely to the flow path 24. The lamella pack 22 extends approximately over an entire cross section of the container 2, which means that it extends approximately from the entire from the inlet 4 to the outlet 8 flowing hydraulic oil flows through or around it. A heat 26 can thus be supplied to the heat pipes 12 to 16 directly or via the lamella pack 22 from the pressure medium in the container 2.

A cooling structure in the form of a lamella pack 28 is also assigned to the pipe sections 20 outside the container 2. This is according to Figure 1 designed in accordance with the disk pack 22. Heat 30 can then be given off from the pipe sections 20 of the heat pipes 12 to 16 directly via the lamella pack 28 to an environment. In addition, a fan 32 is provided, which increases the flow of air through the lamella set 28.

According to Figure 1 the container 2 is thus shown, the cross section of which is penetrated by the lamella pack 22. The plate pack 22 is thermally connected to several heat pipes 12 to 16. The outlet 8 is here on one side of the lamella set 22 and the inlet 4 on the other side. This means that during the During operation, the resulting volume flow of hydraulic oil in container 2 increases the heat transfer from the hydraulic oil to the inner disk pack 22. The heat pipes 12 to 16 then transport the thermal energy to the outer lamella pack 28, the heat transfer to the ambient air being increased here by means of the fan 32.

According to Figure 2 a cooling device 34 is shown. In contrast to the Figure 1 if this has no fan 32 and no outer disk pack 28. Instead, a heat exchanger 36 is provided. This is arranged at the end of the heat pipes 12 to 16. In the case of the heat exchanger, the thermal energy can be given off, for example, via a cooling water circuit or to a thermally inert mass of a machine housing. Here, the thermal energy of the hydraulic unit is bundled in one area and can be made available for further processes if necessary, especially when using several hydraulic units.

According to Figure 3 has a cooling device 38 compared to the embodiment in FIG Figure 1 a reduced inner lamella pack 40. Furthermore, the heat pipes 12 to 16 in the container 2 are shortened. The lamellar pack 40 with the heat pipes 12 to 16 therefore has a smaller cross section within the container 2 and thus does not penetrate the entire cross section of the container 2. A flow guide 42 is provided here to increase the heat transfer. This prevents the hydraulic oil from flowing past the plate pack 40 or the heat pipes 12 to 16. Furthermore, the heat transfer is increased by a higher flow rate of the hydraulic oil. The flow guide 42 is designed as a ramp which extends from the container bottom 44 to the lamella pack 40 or the heat pipes 12 to 16. The lamella pack 40 with the heat pipes 12 to 16 is then arranged in the narrowest cross section of the container 2.

In Figure 4 has the cooling device 46 in contrast to Figure 1 no fan 32. Instead, a motor fan 48 of a motor 50 is used. The motor fan 48 thus serves to cool the motor 50 and to cool the outer lamella set 28 with the heat pipes 12 to 16. A pump 52 is driven by the motor 50. This conveys hydraulic oil via the outlet 8 from the container 2 Figure 4 Thus, the motor 50 with the pump 52, which form a motor-pump unit, is arranged or mounted directly next to the outer disk pack 28, and one of the motor fan 48 The volume flow generated can then increase the heat transfer to the plate pack 28 or to the heat pipes 12 to 16.

A cooling device 54 in Figure 5 has in addition to the heat exchanger 36, see Figure 2 , further heat pipes 56 and 58. The heat pipe 56 is used to cool the motor 50 and the heat pipe 58 is used to cool the pump 52. In addition, further heat pipes can be provided for further sections or components of a hydraulic unit to be cooled. The heat pipes 56, 58 and 12 to 16 are bundled together in the heat exchanger 36 and can be cooled in a targeted manner by a cooling water circuit or can give off heat to the thermally inert mass of the machine housing. The thermal energy is thus bundled and can be used for further processes if required.

The heat pipes 12 to 16 and / or 56, 58 and / or the cooling structure can be components from the computer industry. The heat pipes 12 to 16 with their cooling structure are designed for cooling capacities between 300 and 500 watts, for example.

In Figure 6 a temperature distribution of a lamellar core 60 with heat pipes is shown as an example. It can be seen that a temperature of the lamella set 60 lies in approximately the same temperature range. Heat can thus be given off and / or absorbed over the entire plate pack 60 with approximately the same temperature gradient.

Disclosed is a cooling device for a hydraulic unit, which has a container for hydraulic oil. Two heat pipes are provided for cooling the container. Hydraulic oil in the container flows approximately in a straight line from an inlet to an outlet. The at least two heat pipes are then arranged between the inlet and the outlet.

Reference list

1

Cooling device

2

container

4th

Intake

6th

Hydraulic oil

8th

procedure

10

Hydraulic oil

12

Heat pipe

14th

Heat pipe

16

Heat pipe

18th

Pipe section

20th

Pipe section

22nd

Disk pack

24

Flow path

26th

warmth

28

Disk pack

30th

warmth

32

Fan

34

Cooling device

36

Heat exchanger

38

Cooling device

40

Disk pack

42

Flow guidance

44

Container bottom

46

Cooling device

48

Motor fan

50

engine

52

pump

54

Cooling device

56

Heat pipe

58

Heat pipe

60

Disk pack

Claims (14)

1. Cooling apparatus for a hydraulic assembly, the cooling apparatus having a container (2) for hydraulic oil, which container (2) has an inlet (4) and an outlet (8), at least two heat pipes (12, 14, 16) being arranged in the flow path (24) of the hydraulic oil between the inlet (4) and the outlet (8), each heat pipe (12, 14, 16) having a coolant, and each heat pipe (12, 14, 16) being immersed with one pipe section (20) into the container (2), in order to dissipate heat from the hydraulic oil as heat of evaporation, by the coolant evaporating at a location to be cooled, the heat pipes (12, 14, 16) not being arranged in series as viewed in the direction of the flow path (24).
2. Cooling apparatus according to Claim 1, the flow path (24) extending approximately in one direction between the inlet (4) and the outlet (8).
3. Cooling apparatus according to either of the preceding claims, at least one cooling structure (22, 28) being provided on the at least two heat pipes (12, 14, 16) .
4. Cooling apparatus according to Claim 3, the at least two heat pipes (12, 14, 16) sharing a respective cooling structure (22, 28).
5. Cooling apparatus according to either of Claims 3 and 4, the at least one cooling structure (22, 28) having a multiplicity of cooling fins which are configured as a fin set (22, 28) and which are arranged approximately at a parallel spacing from one another.
6. Cooling apparatus according to one of Claims 3 to 5, a size of the at least one cooling structure (22) in the container (2) corresponding approximately to a flow cross section of the container (2).
7. Cooling apparatus according to one of Claims 3 to 6, the at least one cooling structure (22) being provided on those pipe sections (18) of the at least two heat pipes (12, 14, 16) which are provided within the container (2), and/or the at least one cooling structure (28) being provided on those pipe sections (20) of the at least two heat pipes (12, 14, 16) which are provided outside the container (2).
8. Cooling apparatus according to one of the preceding claims, the at least two heat pipes (12, 14, 16) being cooled outside the container (2) by way of forced convection.
9. Cooling apparatus according to one of the preceding claims, the at least two heat pipes (12, 14, 16) being cooled outside the container (2) by way of a heat exchanger (36).
10. Cooling apparatus according to one of the preceding claims, a flow cross section of the container (2) being reduced in a throttle-like manner in the region of the at least two heat pipes (12, 14, 16).
11. Cooling apparatus according to one of the preceding claims with a hydraulic machine and a drive unit which has a cooling device, it being possible for hydraulic oil to be conveyed from the outlet (8) via the hydraulic machine (52) which can be driven by the drive unit (50), the cooling device of the drive unit (50) being additionally used for cooling of the at least two heat pipes (12, 14, 16).
12. Cooling apparatus according to one of the preceding claims, the cooling apparatus having at least one further heat pipe (56, 58) for a further component (50, 52) of the hydraulic assembly, the at least one further heat pipe (56, 58) being arranged with one pipe section adjacently with respect to the outer pipe section (20) of the at least two heat pipes (12, 14, 16) of the container (2).
13. Cooling apparatus according to one of the preceding claims, the waste heat of at least one heat pipe (12, 14, 16, 56, 58) being provided for at least one further process.
14. Use of the cooling apparatus according to one of the preceding claims for a hydraulic assembly which is configured in such a way that at least the container has a cooling capacity of at most approximately 1000 Watts, preferably of at most from 300 to 500 Watts.

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