Cooling module for a hydraulic machine, hydraulic machine using the same, and hydraulic unit

Abstract

Cooling module (28) for a hydraulic machine (2) comprising a cooling device (26) and a housing section (10), wherein the cooling device (26) is at least partially immersible in a housing interior which is delimited by a housing (6) and a drive unit (16) of the hydraulic machine (2) rotatable therein, and 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). The cooling module (28) is at least partially additively manufactured. Also disclosed are a hydraulic machine (2) with the cooling module (28) and a hydraulic power unit with the hydraulic machine (2).

Description

[0001] 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.

[0002] The heart of a hydraulic circuit is a hydraulic machine, particularly a hydraulic pump. It converts mechanical energy into hydraulic, particularly hydrostatic energy from a pressure medium it pumps. When operated as a hydraulic motor, the conversion occurs in the opposite direction. Losses occur during energy conversion, which, in the case of a hydraulic circuit, particularly lead to heating of the pressure medium. The loss occurring within the hydraulic machine(s) accounts for the majority of the heating of the pressure medium; a much smaller portion is caused by flow losses in pipes. The heating of the pressure medium is particularly significant within the hydraulic pump.

[0003] In conventional solutions, the thermal energy generated in the hydraulic pump due to losses is carried by the pumped pressure fluid into the hydraulic circuit until it is dissipated as heat to a coolant via an external heat exchanger. The thermal energy is distributed over a large oil volume, requiring a large amount of pressure fluid to circulate to dissipate the heat. However, due to the large amount of pressure fluid, the ΔT to the recooling coolant is also comparatively small, so the efficiency of the external heat exchanger is low and its heat exchange surface must be large, which increases investment and operating costs.

[0004] The publications DE 94 11 163 U1, JPH 08 22 64 12, and DE 27 03 686 each show a solution in which cooling is achieved by flushing the interior of the hydraulic pump's housing with pressure fluid. The pressure fluid discharged from the hydraulic pump in this way is recooled with water in a separate heat exchanger. Here, too, the amount of pressure fluid to be circulated is large. Furthermore, the flushed-out amount must be continuously replenished, which entails complex equipment.

[0005] The publication CN 106 224 228 shows a hydraulic pump whose housing is wrapped in a heat pipe. The final heat dissipation occurs by recooling the heat pipe's medium via a water bath. A disadvantage of this solution is, for example, that the heat pipe, due to its external exposure to the hydraulic pump, is exposed to impact damage. A related solution is shown in the publication DE 10 2012 000 986 B3, which proposes a cooling jacket for a hydraulic pump. The disadvantage here is that such a cooling jacket design can require a comparatively large amount of installation space.

[0006] The document WO 2019 / 211100 A1 shows a control disc for a fluid passage control device and the document EP 3 643 928 A1, which is attributable to the applicant, shows a hydraulic control arrangement with a hydraulic control block, in the installation space of which a hydraulic machine is arranged.

[0007] The document EP 37 37 862 A1, which originates from the applicant, shows a hydraulic machine designed as an axial piston machine, in the interior of which a heat exchange tube is accommodated, which extends helically or meanderingly in an annular space between the drive mechanism of the axial piston machine and its housing shell. Due to this arrangement, so close to the heating point, the ΔT is particularly high. Turbulent swirling of a pressure medium quantity present due to a leak in the interior of the housing is also high due to the rotating working chambers. Just one of the two factors mentioned leads to improved heat transfer; both together make the heat transfer particularly efficient. Therefore, a small and simply constructed heat exchange surface in the interior of the housing is sufficient, and particularly efficient cooling is achieved.

[0008] Such integrated heat exchange tubes, however, are not available as standard elements; instead, depending on the application, they are complex to manufacture using tube bending, milling, or casting. This is followed by subsequent joining processes such as soldering or screwing, whereby tightness of the joints must always be ensured. If, for space reasons, additional functions must be integrated adjacent to the cooling system, unfavorable material pairings may arise in these areas due to strength requirements or similar factors, if materials different from those used for the heat exchange tube are used. This, in turn, results in risks to the aforementioned tightness due to different thermal expansion coefficients.

[0009] 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 each hydraulic machine. A further 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.

[0010] The first object is achieved by a cooling module having the features of patent claim 1, the second by a hydraulic machine having the features of claim 13 and the third by a hydraulic unit having the features of claim 14.

[0011] Advantageous further developments of the inventions are described in the respective dependent claims.

[0012] A cooling module for a hydraulic machine has a cooling device which is intended and designed for arrangement in a housing interior of the axial piston machine.

[0013] The housing interior is delimited, in particular, radially by a housing of the hydraulic machine and by a drive mechanism rotatably arranged therein. The housing of the hydraulic machine can have the sole housing function or it can have additional functions, such as integrated valves, or it can also be designed as a support for a drive motor or the like. In particular, the housing is formed by a control block having a pot-shaped recess into which the cooling device and the drive mechanism can be inserted. An inlet of the cooling device is connected, in particular in a fluid-tight manner, 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.The housing section of the cooling module is intended, in particular, for attachment to the housing of the hydraulic machine, in particular for closing the housing interior, and accordingly has fastening means or devices, for example, threaded holes and / or bolts, and / or adjustment means for precise alignment. According to the invention, the cooling module is manufactured additively at least in sections, and the cooling device is formed integrally with the housing section.

[0014] Additive manufacturing makes it possible to customize functional sections of the cooling module, particularly a heat exchange surface and / or a flow cross-section of the cooling device, to meet the required functionality in almost any way. This allows for optimized cooling performance while simultaneously reducing the flow resistance of the cooling device's coolant flow.

[0015] In a preferred development, the cooling module is designed for a hydraulic machine which is constructed as a hydrostatic axial piston machine.

[0016] In this case, the cooling device preferably extends circumferentially and in particular axially, so that it can be immersed into an annular space section of the housing interior that can be delimited by the engine and the housing of the hydrostatic axial piston machine.

[0017] Preferably, a coolant is arranged in the cooling device in a single-phase or two-phase manner, in particular arranged in a flowing manner.

[0018] In a preferred embodiment, at least the cooling device is manufactured additively, at least in sections. In particular, due to additive manufacturing, the 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 heat to be transferred as intended and / or the intended temperature of the pressure medium.

[0019] The housing section can be manufactured at least partially by other means, particularly by machining or additively. Such a hybrid design enables reduced manufacturing costs. For this purpose, the cooling module's functions are grouped according to their manufacturability and combined into component zones. Those that can be manufactured easily and cost-effectively by machining, such as the housing section, particularly in the form of a cover or motor bellhousing, are combined and machined accordingly. Only the cooling device, which is difficult to manufacture conventionally due to its complexity, is manufactured additively. Thus, additive manufacturing is only used where it offers technical and commercial advantages.

[0020] In a further development, the additively manufactured section of the cooling module is molded onto the otherwise manufactured section. This eliminates the need for a complex and time-consuming process for joining the sections using a separate joining process.

[0021] In a further development, the inlet is connected to the inlet channel and / or the outlet is connected to the outlet channel in one area of ​​this additive molding. This eliminates the need for sealants that would be required in this area during conventional manufacturing.

[0022] In a further development, the housing section and the cooling device are made of the same material, making the additive molding particularly easy to form and durable. By avoiding the pairing of different materials, the problem of different thermal expansion coefficients of the sections is also eliminated. Likewise, the associated problems, particularly leakage or contact corrosion, are eliminated.

[0023] The cooling device preferably has a heat exchanger tube with an inlet and an outlet. This tube extends, in particular, in a spiral, meandering, or undulating manner. Deviating from this tube shape, the cooling device can have an interior space with a labyrinth, grid, or sieve shape, or the like.

[0024] 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 at least two windings or layers.

[0025] In a further development, the cooling device is designed to be flow-optimized, at least on the inside or outside, and / or it is designed to be heat-transfer-optimized, at least on the inside or outside. For example, undercuts are created using additive manufacturing that are difficult or only possible with considerable effort using conventional methods.

[0026] In a further development, adjacent coils, meanders, or waves of the heat exchange tube are connected via at least one additively manufactured web, an additively manufactured rib, nub, or the like. Such structures not only provide the cooling device with greater stability, but also contribute to improved heat exchange and, if necessary, to more intensive or improved airflow around the cooling device.

[0027] This effect is further improved if, in a further development, the cooling device has web, rib, knob or hollow body extensions on the outside, which extend into the free space, in the assembled state of the cooling module into the interior of the housing.

[0028] In a further development of the cooling module, the curved sections of the meanders or waves located distal to the housing section have the same crest heights. Thus, when the cooling module is installed, they extend the same axial distance into the housing interior. To accommodate specific installation space conditions in the housing interior and maximize the available heat exchange surface, the meanders or waves in one variant have different crest heights.

[0029] At 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. This provides free space or installation space for a function near the housing section with its inlet and outlet channels.

[0030] In a preferred further development, the inlet or outlet of the cooling device extends in this free space or installation space, in particular parallel to the housing section.

[0031] A hydraulic machine has a housing with an interior and a drive mechanism mounted therein so as to rotate about a rotational axis. In particular, the drive mechanism has cylinder-piston units defining hydrostatic working chambers which, when the drive mechanism rotates, can be alternately connected to a high pressure and a low pressure of the hydraulic machine. During operation of the hydraulic machine, pressure medium leaks into its housing interior. The leakage can, for example, occur radially outwards from the working chambers directly into the housing interior, for example via a sealing gap in the working chambers with a control disk. Additionally or alternatively, the leakage can occur radially inwards from the working chambers via a sealing gap, towards a drive shaft of the hydraulic machine, and be guided into the housing interior via a gap arrangement.Additionally, a leakage line or leakage channel can open into the housing interior, via which a leakage volume flow of an external component can be supplied to the housing interior, and thus to the cooling device of the cooling module. In this way, not only the pressure medium escaping 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 designed according to at least one aspect of the preceding description is immersed with its cooling device into the housing interior delimited by the housing and the drive mechanism, 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.

[0032] Thanks to additive manufacturing, the cooling module according to the invention can be easily customized to the individual conditions and geometries of the respective hydraulic machine. The associated advantages have already been explained in the course of the description of the cooling module, so they need not be mentioned again.

[0033] The hydraulic machine is preferably designed as an axial piston machine, in particular in a swashplate design, with the pistons of the cylinder-piston units being slidably supported on a swashplate that is fixed to the housing or pivotably mounted. The drive mechanism of the axial piston machine is preferably completely encompassed by the cooling device, both axially and at least in sections.

[0034] In a further development, the swash plate is also completely and axially at least partially encompassed by the cooling device.

[0035] Alternatively, a bent-axis design is possible.

[0036] In a further development, the housing interior extends as an annular space around the rotational axis, in particular predominantly cylindrical, conical, or oval. The cooling device surrounds the rotational axis in a particularly polygonal manner, particularly square, hexagonal, octagonal, or decagonal, although an odd number of corners is also possible.

[0037] 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.

[0038] The hydraulic machine can be designed as a hydraulic pump or as a hydraulic motor, or it can be designed to be operable as both a hydraulic pump and a hydraulic motor.

[0039] A hydraulic unit has a hydraulic machine configured according to at least one aspect of the preceding description. Its housing is rigidly connected to at least one drive motor, via which torque can be transmitted to the axial piston machine.

[0040] In a further development of the unit, the drive motor is designed as an electric machine.

[0041] Particularly when the drive motor is fluid- or water-cooled, a further development of the unit proves advantageous in which the cooling of the drive motor is fluidly connected to the cooling module of the hydraulic machine. This can be configured in a fluidic series or parallel circuit. This reduces the number of external interfaces of the unit, making it easier to integrate the unit into a customer environment. A further reduction in external interfaces is possible through the following developments.

[0042] In addition, in a further development, a pressure medium container which can be connected to the low pressure of the hydraulic machine, a hydraulic cylinder which can be supplied with pressure medium by the hydraulic machine, and / or a control block, in particular a valve control block, via which a pressure medium volume flow for supplying pressure medium to the hydraulic cylinder can be controlled, are firmly connected to the housing of the hydraulic machine.

[0043] Such a unit can be used to create an extremely compact hydraulic linear drive with integrated drive motor, integrated control and integrated cooling.

[0044] The unit is designed to be 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 fluid channels, but also serves as a support component, to which the aforementioned components of the unit are flanged or attached. In this way, interfaces within the perimeter of the unit are accommodated in a space-saving manner, and in addition, the number of external interfaces of the unit can be significantly reduced.

[0045] In a further development, a low-pressure channel of the unit, to which leakage chambers of said components are or can be fluidly connected, opens into the housing interior. In this way, the leakage from these components can also be fed to the cooling device located in the housing of the hydraulic machine and cooled by it.

[0046] One embodiment of a cooling module according to the invention, one of an axial piston machine according to the invention, and one of an assembly according to the invention are shown in the drawings. The invention will now be explained in more detail with reference to the figures in these drawings.

[0047] They show: 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 a cooling module of the axial piston machine according to Figure 1 in partial perspective view, Figure 3 the cooling module according to Figure 2 in partial perspective and partially sectioned view, Figure 4 the cooling module according to Figures 2 and 3 in a longitudinal section, and Figure 5 a cross-section of the cooling module in perspective view.

[0048] According to Figure 1a hydraulic unit 1 has a hydraulic machine designed as a hydrostatic axial piston pump 2 with a pot-shaped housing 4 with a housing shell 6, which has a pot base 8 on the front side on the one hand and is closed on the other hand by a cover-shaped housing section 10. 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 rolling bearings (not shown). A cylinder drum 16 is connected in a rotationally fixed manner to the drive shaft 14, into 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 for axial displacement in the respective cylinder bore and is slidably supported by the housing section 10 on a swash plate 22 fixedly arranged thereon.Opposite, between the cylinder drum 16 and the pot base 8, a control disc 24 is arranged, interspersed with through-holes (not shown). The through-holes (pressure kidneys) are in pressure medium communication with a high-pressure connection formed on the pot base 8 and a low-pressure connection (not shown). Further explanation of the basic structure of the axial piston machine 2 can be omitted at this point, since this machine type is sufficiently known from the prior art.

[0049] In addition, a hollow cooling device 26 through which coolant can flow is arranged in an annular space defined by the housing shell 6 and the cylinder drum 16 for dissipating thermal energy from the housing 4. This cooling device fully surrounds the cylinder drum 16 and serves to cool pressure medium that leaks into the housing interior. As already mentioned, the hottest and most loss-prone point in a hydraulic circuit is located in the hydrostatic axial piston machine 2. Accordingly, the pressure medium also has the highest temperature there. The cooling device 26 arranged in the annular space transfers the thermal energy at precisely this point to a coolant, for example water, flowing therein. As a result, the ΔT at this point is very high, and so is the heat transfer coefficient α. This allows a large amount of heat to be transferred over a small heat exchange surface.As a result, a significantly larger heat exchanger, which would otherwise have to be provided externally, is eliminated. Due to its additive manufacturing, the cooling device 26 has an optimized geometry with regard to flow pressure loss and heat transfer, allowing it to be designed particularly compactly. The cooling device 26 is made of the same material as the housing section 10 and is additively formed onto it, i.e., additively connected to it. The housing section 10, in turn, is manufactured cost-effectively by machining, since its geometry does not require complex shapes, but merely requires high strength.

[0050] In the illustrated embodiment, the housing 4, with a housing shell 6 and a housing base or pot base 8, is formed by a control block of the unit 1, which in particular supports control valves and a motor pump housing (not shown). The axial piston unit 2, the control block, the cooling module 28 or 10, 26, the motor pump housing, and the shaft 12 are thus combined into an extremely compact component with minimal installation space requirements.

[0051] The housing section 10 forms together with the cooling device 26 a one-piece cooling module 28, the structure of which is shown in the Figures 2 to 5 is explained in more detail.

[0052] According to Figure 2An inlet channel 32 and an outlet channel 34 for supplying coolant to the cooling device 26 open at an edge 30 of the machined, plate-shaped housing section 10. The coolant can be water or another suitable fluid. Both 32 and 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 provided for fastening bolts 36 (see Figure 1 ) of axis 12 are provided.

[0053] Extending centrally from a plate-shaped base body of the housing section 10 is a cylindrical base 38, to which the cooling device 26 is attached in the illustrated embodiment. This base is designed as a meandering heat exchanger tube, whose inlet 40 is connected to the inlet channel 32 and whose outlet 42 is connected to the outlet channel 34. Meanders 44 of the cooling device extend axially with parallel longitudinal sections 46, with adjacent longitudinal sections 46 being alternately connected distally and proximally via a base section 48.

[0054] At least two adjacent longitudinal sections 46 are connected via a series of struts 50, in the embodiment shown with alternating strut angles, in particular to increase strength and / or to improve heat transfer.

[0055] Figure 3shows a longitudinal section through the cooling module 28, laterally offset from a central axis of the cooling device and in a perspective view. Clearly visible here is an interface or transition 52 from the machined, plate-shaped housing section 10 to the additively manufactured cooling device 26, i.e., the meandering heat exchanger tube.

[0056] Furthermore, the view provides a clear view of hollow body extensions 54 extending axially along the curved sections 48. These have a cuboid shape with two axially open chambers 56 and enlarge the heat exchange surface of the cooling device 26. Due to the additive manufacturing, a high degree of freedom in the design of the cooling device 26 is provided at this point, both with regard to the internal flow cross-section and on the outside towards the housing interior.

[0057] Figure 4shows a longitudinal section of the cooling module 28. The housing section 10 has an axially extending, stepped cylindrical through-hole 58 into which the swash plate 22 is inserted according to Figure 1 can be used in a rotationally fixed manner. The interface 52, where the machined section 10, 38 of the cooling module 28 transitions into the additively manufactured section 26, is clearly visible here. The position of the interface 52 can, of course, be selected differently, adapted to specific requirements and grouped according to the respective function and its manufacturability.

[0058] One such possibility is shown by the Figure 5 Here, an interface 52', at which the machined housing section 10 merges into the additively manufactured cooling device 26, is arranged offset by a distance from an end face 60 of the housing section 10.

[0059] In addition, kidney-shaped bases 62 arranged on a partial circle are machined, to which arc sections of the cooling device 26 are attached (not shown).

[0060] Disclosed is a cooling module for a hydraulic machine, the flow-through cooling device of which is formed integrally with a base body of the cooling module designed for fastening, and which is additively manufactured at least in sections, wherein the cooling device is provided for arrangement, in particular for insertion or immersion, in a housing of the hydraulic machine, between its drive mechanism and the housing.

[0061] Also disclosed is a hydraulic machine with such a cooling module, wherein a housing section of the hydraulic machine, in particular a housing cover or flange, is formed by the base body. Furthermore, a hydrostatic unit with the hydraulic machine is disclosed, wherein a drive motor, in particular an electric motor, is firmly connected to the housing. List of reference symbols:

[0062] 1 hydraulic unit 2 axial piston pump 4 housing 6 housing shell 8 pot base 10 housing section 12 hydraulic axis 14 drive shaft 16 cylinder drum 18 rotary axis 20 working piston 22 swash plate 24 control disc 26 cooling device 28 cooling module 30 edge 32 inlet channel 34 outlet channel 36 fastening bolt 38, 38 base 40 inlet 42 outlet 44 meander / wave 46 longitudinal section 48 base section 50 struts 52, 52 interface 54 cavity extension 56 chamber 58 through-hole 60 front face 62 base

Claims

1. Cooling module for a hydraulic machine (2), which has a cooling device (26), at least certain portions of which can be immersed in a housing interior, which can be delimited by a housing (6) and an engine (16), which can rotate therein, of the hydraulic machine (2), wherein an inlet (40) of the cooling device (26) is connected to an inlet channel (32) of a housing portion (10), and an outlet (42) of the cooling device (26) is connected to an outlet channel (34) of the housing portion (10), characterized in that at least certain portions of the cooling module (28) are additively manufactured and in that the housing portion (10) forms a one-piece cooling module (28) together with the cooling device (26).

2. Cooling module according to Claim 1, wherein the cooling device extends circumferentially, so that it can surround at least certain portions of the engine.

3. Cooling module according to Claim 1 or 2, wherein the housing portion (10) and the cooling device (26) are manufactured from the same material.

4. Cooling module according to one of Claims 1 to 3, wherein at least certain portions of the cooling device (26) are additively manufactured and at least certain portions of the housing portion (10) are manufactured differently, in particular machined.

5. 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.

6. Cooling module according to Claim 5, wherein adjacent helices, meanders or undulations of the heat exchange tube are connected via at least one web (50), rib, stud or the like.

7. Cooling module according to one of the preceding claims, wherein the outside of the cooling device (26) has web extensions, rib extensions, stud extensions or hollow body extensions (54).

8. Cooling module at least according to Claim 5 or 6, wherein curved portions (48) of the meanders or undulations arranged distally from the housing portion (10) have the same apex heights.

9. Cooling module at least according to Claim 5, 6 or 8, wherein at least one of the curved portions of the meanders or undulations arranged adjacent to the housing portion has a lower apex height there.

10. Cooling module according to Claim 9, wherein the inlet (40) or outlet extends between the curved portion with a lower apex height and the housing portion (10).

11. Cooling module according to one of the preceding claims, wherein the cooling device (26) is configured to be optimized in terms of flow at least on the inside, and / or wherein the cooling device (26) is configured to be optimized in terms of heat transfer at least on the inside or outside.

12. Cooling module according to one of the preceding claims, wherein the cooling device (26) has undercuts, in particular for optimization in terms of flow and / or heat-exchange.

13. Hydraulic machine having a housing (4, 6, 8) having a housing interior and an engine (16), which is mounted so as to be rotatable therein about an axis of rotation (18), and having a leakage of pressure medium into the housing interior during intended operation of the hydraulic machine (2), wherein the cooling device (26) of a cooling module (28), which is configured according to one of the preceding claims, is immersed in the housing interior, and wherein certain portions of the housing interior are delimited by the housing portion (10) of the cooling module (28).

14. Hydraulic unit having a hydraulic machine (2) according to Claim 13, a drive machine being fixedly connected to the housing (4, 6, 8) of said hydraulic machine.

15. Unit according to Claim 14, wherein the drive machine has a fluid-cooled configuration 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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