EP4060185A1 - Cooling module for a hydraulic machine, hydraulic machine using the same, and hydraulic unit - Google Patents

Abstract

Cooling module (28) for a hydraulic machine (2) with a cooling device (26) and a housing section (10), wherein the cooling device (26) can be immersed, at least in sections, into a housing interior which is defined by a housing (6) and an engine ( 16) of the hydraulic machine (2) can be limited, and wherein an inlet (40) of the cooling device (26) with an inlet duct (32) of a housing section (10) and an outlet (42) of the cooling device (26) with an outlet duct (34) of the housing section (10) are connected. The cooling module (28) is additively manufactured at least in sections. Also disclosed are a hydraulic machine (2) with the cooling module (28) and a hydraulic unit with the hydraulic machine (2).

Description

The invention relates to a cooling module for a hydraulic machine according to the preamble of patent claim 1, a hydraulic machine with this according to claim 13 and a hydraulic unit with the hydraulic machine according to claim 14.

The heart of a hydraulic circuit is a hydraulic machine, in particular a hydraulic pump. It is used to convert mechanical energy into hydraulic energy, in particular into hydrostatic energy, of a pressure medium conveyed by it. In the case of operation as a hydraulic motor, the conversion takes place in the opposite direction. During energy conversion, losses occur which, in the case of the hydraulic circuit, lead in particular to heating of the pressure medium. The loss occurring within the hydraulic machine or machines is responsible for the majority of the heating of the pressure medium, a much smaller part is caused by flow losses in lines. The heating of the pressure medium within the hydraulic pump is particularly high.

In conventional solutions, the thermal energy that occurs as a result of losses in the hydraulic pump is carried away by the pumped pressure medium into the hydraulic circuit until it is dissipated as heat to a coolant by means of an external heat exchanger. Here, the thermal energy is distributed over a large volume of oil, which means that a large amount of pressure medium has to be circulated in order to dissipate the heat. Due to the large amount of pressure medium, however, a ΔT to the recooling coolant is comparatively small, so that the efficiency of the external heat exchanger is low and its heat exchange surface must be large, which keeps investment and operating costs high.

The pamphlets DE 94 11 163 U1 , JPH 08 22 64 12 and DE 27 03 686 each show a solution in which the cooling means of flushing the interior of the housing Hydraulic pump takes place with pressure medium. The pressure medium discharged from the hydraulic pump in this way is recooled with water in a separately arranged heat exchanger. Here, too, the amount of pressure medium to be circulated is large. In addition, the quantity flushed out has to be continuously replenished, which entails expense in terms of device technology.

The pamphlet CN 106 224 228 shows a hydraulic pump whose housing is wrapped in a heat pipe. The heat is finally dissipated by re-cooling the heat pipe medium in a water bath. A disadvantage of this solution is, for example, that the heat pipe is exposed to damage from impact due to its external exposure to the hydraulic pump. The publication shows a related solution DE 10 2012 000 986 B3 , in which a cooling jacket for a hydraulic pump is proposed. The disadvantage here is that such a cooling jacket design can take up a comparatively large amount of space.

The document going back to the applicant EP 37 37 862 A1 shows a hydraulic machine designed as an axial piston machine, in the interior of which a heat exchange tube is accommodated, which extends in a helical or meandering manner in an annular space between the engine of the axial piston machine and its housing jacket. Due to this arrangement, so close to the point of heating, the ΔT is particularly high. A turbulent turbulence of a quantity of pressure medium present due to the leakage in the interior of the housing is also high due to the rotating work spaces. Just one of the two factors mentioned leads to an improved heat transfer, both together make the heat transfer particularly efficient. A small and simply constructed heat exchange surface in the interior of the housing is therefore sufficient and particularly efficient cooling is achieved.

However, such integrated heat exchange tubes are not available as standard elements; depending on the application, they are expensive to produce by means of tube bending, milling or casting. In addition, there are subsequent joining processes by means of soldering or screwing, whereby attention must always be paid to the tightness of the joints. If, for reasons of space, further functions have to be integrated in addition to cooling, this can be done in these areas due to strength requirements or the like to unfavorable material pairings if materials other than the heat exchange tube are used. This in turn results in risks for said tightness due to different coefficients of thermal expansion.

In contrast, the invention is based on the object of creating an integrable cooling module for a hydraulic machine that can be manufactured with less effort for a respective hydraulic machine. Another object is to create a hydraulic machine with integrated cooling that is less complex to manufacture and a third object is to create a hydraulic unit with a hydraulic machine with integrated cooling that is less complex to manufacture.

The first task is solved by a cooling module with the features of patent claim 1, the second by a hydraulic machine with the features of claim 13 and the third by a hydraulic unit with the features of claim 14.

Advantageous developments of the invention are described in the respective dependent claims.

A cooling module for a hydraulic machine has a cooling device that is provided and designed for arrangement in a housing interior of the axial piston machine. The housing interior can be delimited, in particular radially, by a housing of the hydraulic machine and by a power unit that is rotatably arranged therein. The housing of the hydraulic machine can only have the housing function or it has other functions, such as integrated valves, or it is also designed as a support for a drive machine or the like. In particular, the housing is formed by a control block which has a pot-like recess into which the cooling device and the engine can be inserted. An inlet of the cooling device is connected to an inlet channel and an outlet of the cooling device is connected to an outlet channel of a housing section of the cooling module, in particular in a fluid-tight manner. The housing section of the cooling module is provided in particular for attachment to the housing of the hydraulic machine, in particular for closing the housing interior and has accordingly Fasteners or devices, such as threaded holes and / or bolts, and / or adjusting means for precise alignment. According to the invention, the cooling module is additively manufactured at least in sections. In particular, the cooling device is designed in one piece with the housing section.

Additive manufacturing makes it possible to design functional sections of the cooling module, in particular a heat exchange surface and/or a flow cross section of the cooling device, in almost any way with the required functionality. In this way, an optimized cooling capacity can be achieved with a simultaneously reduced flow resistance of a coolant flow of the cooling device.

In a preferred development, the cooling module is designed for a hydraulic machine that is designed as a hydrostatic axial piston machine.

In this case, the cooling device preferably extends circumferentially and in particular axially, so that it can be immersed in an annular space section of the housing interior that can be delimited by the engine and the housing of the hydrostatic axial piston machine.

Preferably, a single-phase or two-phase coolant is arranged in the cooling device, in particular arranged to flow.

In a preferred development, at least the cooling device is additively manufactured, at least in sections. In particular, due to additive manufacturing, an external shape of the cooling device, its flow cross section, its wall thickness and/or its material can be designed with a high degree of freedom, at least depending on the intended heat to be transferred and/or the intended temperature of the pressure medium.

The housing section can be manufactured in some other way, in particular by machining, or additively, at least in sections. Such a hybrid design allows for reduced production costs. For this purpose, functions of the cooling module are grouped according to their manufacturability and summarized in component zones. Those that are easy and inexpensive to produce by machining, such as the Housing section, in particular in the form of a cover or motor bellhousing, are combined and manufactured accordingly by cutting. Only the cooling device, which is difficult to produce conventionally due to its complexity, is additively manufactured. Additive manufacturing is therefore only used where it brings technical and commercial advantages.

In a development, the additively manufactured section of the cooling module is additively formed onto the otherwise manufactured section. In this way, there is no need to connect the sections by means of a separate joining method, which is difficult to master in terms of process technology and is complex.

In a further development, the inlet is connected to the inlet channel and/or the outlet to the outlet channel in one area of this additive molding. In this way, sealing means that would have to be provided in this area in conventional production can be dispensed with.

In a development, the housing section and the cooling device are made from the same material, so that the additive molding can be formed particularly well and is durable. Due to the pairing of different materials that is avoided in this way, the problem of different coefficients of thermal expansion of the sections is also eliminated. The same applies to the subsequent problems associated with this, in particular leakage or contact corrosion.

The cooling device preferably has a heat exchange tube having the inlet and the outlet. This extends in particular in a helical, meandering or undulating manner. Deviating from this tube shape, the cooling device can have an interior space with a labyrinth, lattice or sieve shape or the like.

Heat transfer is further improved if, in a further development, the cooling device, in particular the heat exchange tube, extends in the radial direction with one or with at least two windings or layers.

In a further development, the cooling device is designed to be flow-optimized at least on the inside or outside, and/or it is at least on the inside or designed to be heat transfer-optimized on the outside. For example, undercuts are formed for this purpose using additive manufacturing, which can hardly be produced conventionally or only with great effort.

In a further development, for this purpose adjacent coils, meanders or corrugations of the heat exchange tube are connected via at least one additively manufactured web, an additively manufactured rib or nub or the like. On the one hand, such structures give the cooling device greater stability and, on the other hand, they contribute to better heat exchange and possibly to more intensive or better flow around the cooling device.

This effect is further improved if, in a further development, the cooling device has web, rib, nub or hollow body extensions on the outside, which extend into the free space, in the installed state of the cooling module into the interior of the housing.

In a further development of the cooling module, arcuate sections of the meanders or waves arranged distally of the housing section have the same crest heights, and when the cooling module is in the mounted state they thus protrude the same distance into the housing interior in the axial direction. In order to respond to specific installation space conditions in the interior of the housing and to maximize the available heat exchange surface, the meanders or waves have different crest heights in one variant.

On an end section of the cooling device adjacent to the housing section, at least one curved section of the meanders or waves has a lower crest height than the others. In this way, free or installation space is reserved for a function near the housing section with its inlet channel and outlet channel.

In a preferred development, the inlet or outlet of the cooling device extends in this free space or installation space, in particular parallel to the housing section.

A hydraulic machine has a housing with a housing interior and an engine mounted therein so that it can rotate about an axis of rotation. In particular, the engine Cylinder-piston units, of which hydrostatic working spaces are limited, which are alternately connected to a high pressure and a low pressure of the hydraulic machine during rotation of the engine. When the hydraulic machine is in operation, pressure medium leaks into its housing interior. The leakage can occur, for example, from the working spaces radially outwards directly into the housing interior, for example via a sealing gap of the working spaces with a control disk. In addition or as an alternative, the leakage from the working chambers can occur radially inwards via a sealing gap, towards a drive shaft of the hydraulic machine, and be conducted via a gap arrangement into the housing interior. In addition, a leakage line or a leakage channel can open into the interior of the housing, via which a leakage volume flow of an external component can be supplied to the interior of the housing and thus to the cooling device of the cooling module. In this way, not only the pressure medium emerging from the working chambers of the hydraulic machine, but also the pressure medium of a hydraulic unit can be cooled. According to the invention, a cooling module configured according to at least one aspect of the preceding description has its cooling device immersed in the housing interior delimited by the housing and the engine, and the housing interior is delimited at least in sections by the housing section of the cooling module. In particular, the housing can be closed, in particular closed, via the housing section of the cooling module.

Due to the additive manufacturing, the cooling module according to the invention can easily be adapted to the individual circumstances and geometries of the respective hydraulic machine. The advantages associated with this have already been presented in the course of the description of the cooling module, so that it is not necessary to mention them again.

The hydraulic machine is preferably designed as an axial piston machine, in particular in the form of a swash plate, with the pistons of the cylinder-piston units being slidably supported on a swash plate which is arranged fixed to the housing or is pivotably mounted. In this case, the engine of the axial piston machine is preferably surrounded by the cooling device over the entire circumference and axially at least in sections.

In a further development, the swash plate is also completely and axially surrounded by the cooling device at least in sections.

Alternatively, a bent-axis design is possible.

In a development, the housing interior extends as an annular space around the axis of rotation, in particular in a predominantly cylindrical or conical or oval manner. The axis of rotation is encompassed by the cooling device in particular in a polygonal manner, in particular in a four-, six-, eight-, or ten-cornered manner, with odd numbers of corners also being possible.

In particular, the housing is formed by a control block in which at least one additional function, such as a control or other valve, is provided.

The hydraulic machine can be designed as a hydraulic pump or as a hydraulic motor, or it is designed to be operable as a hydraulic pump and as a hydraulic motor.

A hydraulic unit has a hydraulic machine that is designed according to at least one aspect of the preceding description. In this case, its housing is firmly connected to at least one drive machine, via which a torque can be transmitted to the axial piston machine.

In a development of the unit, the drive machine is designed as an electric machine.

In particular, if the drive machine is designed to be fluid- or water-cooled, a further development of the unit has proven to be advantageous in which the cooling of the drive machine is fluidically connected to the cooling module of the hydraulic machine. This can be configured in a fluidic series or parallel connection. This reduces the number of interfaces of the unit to the outside, so that the unit can be integrated more easily into a customer environment. An additional reduction in interfaces to the outside is possible through the following developments.

In addition, in a further development, a pressure medium tank, which can be connected to the low pressure of the hydraulic machine, a hydraulic cylinder, which can be connected to the hydraulic machine Pressure medium can be supplied, and/or a control block, in particular a valve control block, via which a pressure medium flow rate for supplying pressure medium to the hydraulic cylinder can be controlled, is firmly connected to the housing of the hydraulic machine.

An extremely compact hydraulic linear drive with an integrated drive machine, integrated control and integrated cooling can be formed via such a unit.

The unit is particularly compact if the housing of the hydraulic machine, as already mentioned above, is formed by the control block, which not only carries hydraulic control functions such as control valves and pressure medium channels and the like, but also serves as a support component, with the mentioned Components of the unit are flanged or fastened. In this way, interfaces are accommodated within the scope of the unit in a space-saving manner and, in addition, the number of interfaces of the unit to the outside can be greatly reduced.

In a further development, a low-pressure channel of the unit, with which the leakage chambers of said components can be fluidly connected or are connected, opens into the interior of the housing. In this way, the leakage from these components can also be fed to the cooling device arranged in the housing of the hydraulic machine and cooled by it.

One exemplary embodiment each of a cooling module according to the invention, an axial piston machine according to the invention, and a unit according to the invention is shown in the drawings. The invention will now be explained in more detail on the basis of the figures in these drawings.

• Figur 1 ein hydrostatisches Aggregat mit einer als Axialkolbenmaschine ausgebildeten Hydromaschine und einer hydraulischen Achse gemäß einem Ausführungsbeispiel, in einer teilgeschnittenen Seitenansicht,
• Figur 2 ein Kühlmodul der Axialkolbenmaschine gemäß Figur 1 in teilperspektivischer Ansicht,
• Figur 3 das Kühlmodul gemäß Figur 2 in teilperspektivischer und teilgeschnittener Ansicht,
• Figur 4 das Kühlmodul gemäß Figur 2 und 3 in einem Längsschnitt, und
• Figur 5 einen Querschnitt des Kühlmoduls in perspektivischer Darstellung.

Show it:

• figure 1 a hydrostatic unit with a hydraulic machine designed as an axial piston machine and a hydraulic axis according to an embodiment, in a partially sectioned side view,
• figure 2 according to a cooling module of the axial piston machine figure 1 in partial perspective view,
• figure 3 the cooling module according to figure 2 in a partially perspective and partially sectioned view,
• figure 4 the cooling module according to Figure 2 and 3 in a longitudinal section, and
• figure 5 a cross section of the cooling module in a perspective view.

According to figure 1 For example, a hydraulic unit 1 has a hydraulic machine designed as a hydrostatic axial piston pump 2 with a pot-shaped housing 4 with a housing jacket 6 which has a pot bottom 8 on the front side and is closed by a cover-shaped housing section 10 on the other side. The housing section 10 is connected to a cylinder housing of a linear axis 12 . A drive shaft 14 is rotatably mounted in the housing 4 via roller bearings (not shown). A cylinder drum 16 is connected in a rotationally fixed manner to the drive shaft 14 , in which a plurality of cylinder bores are introduced parallel to the axis of rotation 18 along a pitch circle arranged concentrically to the axis of rotation 18 . A hydrostatic working piston 20 is guided in an axially displaceable manner in the respective cylinder bore and is slidably supported on the side of the housing section 10 on a swash plate 22 arranged fixedly thereon. On the opposite side, between the cylinder drum 16 and the pot base 8, there is a control disc 24 through which through-holes (not shown) pass. The through-hole (pressure kidneys) are in fluid communication with a high-pressure connection formed on the bottom 8 of the pot and a low-pressure connection (not shown). A further explanation of the basic structure of the axial piston machine 2 can be omitted at this point, since this type of machine is well known from the prior art.

In addition, a hollow cooling device 26 through which coolant can flow is arranged in an annular space delimited by the housing jacket 6 and the cylinder drum 16 for dissipating thermal energy from the housing 4 . This completely surrounds the cylinder drum 16 and is used to cool pressure medium entering the housing interior due to leakage. As already mentioned, the hottest and most lossy point in a hydraulic circuit is in the hydrostatic axial piston machine 2. Accordingly, the pressure medium mentioned also has the highest temperature there. Due to the cooling device 26 arranged in the annular space, the thermal energy is applied precisely at this point a coolant flowing therein, for example water, is transferred. As a result, a ΔT is very high at this point and so is the heat transfer coefficient α. This means that a large amount of heat can be transferred over a small heat exchange surface. As a result, there is no longer a significantly larger heat exchanger that would have to be provided externally. Due to its additive manufacturing, the cooling device 26 has an optimized geometry with regard to flow pressure loss and heat transfer and can thus be designed in a particularly compact manner. The cooling device 26 consists of the same material as the housing section 10 and is additively formed onto it, ie additively connected to it. The housing section 10 is in turn manufactured in a cost-effective manner by machining, since its geometry does not have to have any complex shapes, just high strength.

The housing 4 with a housing jacket 6 and a housing base or pot base 8 is formed in the exemplary embodiment shown by a control block of the unit 1, which in particular carries control valves and a motor bellhousing (not shown). The axial piston machine 2, the control block, the cooling module 28, or 10, 26, the motor bellhousing and the axis 12 are thus aggregated into an extremely compact component with minimal installation space requirements.

The housing section 10 forms, together with the cooling device 26, a one-piece cooling module 28, whose structure in the Figures 2 to 5 is explained in more detail.

According to figure 2 an inlet duct 32 and an outlet duct 34 for the coolant supply of the cooling device 26 open out on an edge side 30 of the machined, plate-shaped housing section 10. The coolant can be water or another suitable fluid. Both 32, 34 are each provided with an internal thread for receiving connection sockets. In the axial direction, the plate-shaped housing section 10 is penetrated by through-holes which are suitable for fastening bolts 36 (cf. figure 1 ) of the axis 12 are provided.

A base 38, which is cylindrical in the exemplary embodiment shown, extends centrally from a plate-shaped base body of the housing section 10 and on which the cooling device 26 is attached. This is designed as a meandering heat exchange tube, the inlet 40 with the inlet channel 32 and the outlet 42 with the Drain channel 34 is connected. Meanders 44 of the cooling device extend axially with parallel longitudinal sections 46, with adjacent longitudinal sections 46 being connected alternately distally and proximally via a base section 48.

At least two adjacent longitudinal sections 46 are connected via a row of struts 50, in the exemplary embodiment shown with alternating strut angles, in particular to increase the strength and/or to improve the heat transfer.

figure 3 shows a longitudinal section through the cooling module 28, offset laterally to a central axis of the cooling device and in a perspective view. In particular, an interface or a transition 52 from the machined, plate-shaped housing section 10 to the additively manufactured cooling device 26, that is to say the meandering heat exchange tube, can be seen clearly here.

The view also gives a clear view of the hollow body extensions 54 that extend axially on the curved sections 48. These have a cuboid shape with two axially open chambers 56 and increase the heat exchange surface of the cooling device 26. Due to additive manufacturing, there are high degrees of freedom at this point Design of the cooling device 26, given both the inner flow cross-section regarding as well as the outside toward the housing interior.

figure 4 shows a longitudinal section of the cooling module 28. The housing section 10 has an axially extending, stepped-cylindrical through-hole 58, in which the swash plate 22 according to figure 1 can be used in a rotationally fixed manner. The interface 52, at which the machined section 10, 38 of the cooling module 28 merges into the additively manufactured section 26, is clearly visible here. The position of the interface 52 can of course be chosen differently, adapted to specific requirements and grouped according to the respective function and its manufacturability.

Such a possibility shows the figure 5 . Here is an interface 52', at which the machined housing section 10 fits into the additively manufactured cooling device 26 transitions, offset by a distance from an end face 60 of the housing section 10 .

In addition, kidney-shaped bases 62 arranged on a pitch circle are machined, on which curved sections of the cooling device 26 attach (not shown).

Disclosed is a cooling module for a hydraulic machine, the flow-through cooling device of which is formed in one piece with a base body of the cooling module designed for attachment, and which is additively manufactured at least in sections, the cooling device for arrangement, in particular for insertion or immersion, in a housing of the hydraulic machine, between whose engine and the housing is provided.

Also disclosed is a hydraulic machine with such a cooling module, with a housing section of the hydraulic machine being formed by the base body, in particular a housing cover or flange. Furthermore, a hydrostatic unit with the hydraulic machine is disclosed, with a drive machine, in particular an electric machine, being firmly connected to its housing.

Reference list:

1

hydraulic aggregate

2

axial piston pump

4

Housing

6

housing jacket

8th

pot bottom

10

housing section

12

hydraulic axis

14

drive shaft

16

cylinder drum

18

axis of rotation

20

working piston

22

swashplate

24

control disc

26

cooling device

28

cooling module

30

edge side

32

inlet channel

34

drain channel

36

mounting bolts

38, 38'

base

40

Intake

42

process

44

meander/wave

46

longitudinal section

48

bottom section

50

striving

52, 52'

interface

54

cavity process

56

chamber

58

through hole

60

face

62

base

Claims (15)

Cooling module for a hydraulic machine (2), which has a cooling device (26) which can be immersed, at least in sections, into a housing interior space which can be delimited by a housing (6) and an engine (16) of the hydraulic machine (2) which can be rotated therein, wherein an inlet (40) of the cooling device (26) is connected to an inlet channel (32) of a housing section (10) and an outlet (42) of the cooling device (26) is connected to an outlet channel (34) of the housing section (10), characterized in that the cooling module (28) is additively manufactured at least in sections. Cooling module according to claim 1, wherein the cooling device extends circumferentially, so that the engine can be encompassed by it at least in sections. Cooling module according to claim 1 or 2, wherein the housing section (10) and the cooling device (26) are made of the same material. Cooling module according to one of Claims 1 to 3, in which the cooling device (26) is produced additively, at least in sections, and the housing section (10) is produced in some other way, in particular by cutting, at least in sections. Cooling module according to one of the preceding claims, wherein the cooling device (26) has a heat exchange tube which has the inlet (40) and the outlet (42) and extends in a helical, meandering or undulating manner. Cooling module according to claim 5, wherein adjacent coils, meanders or corrugations of the heat exchange tube are connected via at least one web (50), a rib, knob or the like. Cooling module according to one of the preceding claims, wherein the cooling device (26) has web, rib, nub or hollow body extensions (54) on the outside. Cooling module at least according to claim 5 or 6, wherein curved sections (48) of the meanders or waves arranged distally of the housing section (10) have the same crest heights. Cooling module at least according to Claim 5, 6 or 8, wherein at least one of the curved sections of the meanders or waves arranged adjacent to the housing section has a lower crest height there. Cooling module according to Claim 9, in which the inlet (40) or outlet extends between the curved section with a lower crest height and the housing section (10). Cooling module according to one of the preceding claims, wherein the cooling device (26) is designed to be flow-optimized at least on the inside, and/or wherein the cooling device (26) is designed to be heat transfer-optimized at least on the inside or outside. Cooling module according to one of the preceding claims, wherein the cooling device (26) has undercuts, in particular for flow and/or heat exchange optimization. Hydraulic machine with a housing (4, 6, 8) with a housing interior and an engine (16) mounted therein so that it can rotate about an axis of rotation (18), and with a leakage of pressure medium into the housing interior when the hydraulic machine (2) is operated as intended, wherein a Cooling module (28) designed according to one of the preceding claims, with its cooling device (26) immersed in the housing interior, and wherein the housing interior is delimited in sections by the housing section (10) of the cooling module (28). Hydraulic unit with a hydraulic machine (2) according to Claim 13, with the housing (4, 6, 8) of which a drive machine is firmly connected. Unit according to claim 14, wherein the drive machine is designed to be fluid-cooled and a cooling device of the drive machine and the cooling device of the cooling module of the hydraulic machine are fluidically connected.

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