Electro-hydraulic drive system

Abstract

The utility model relates to an electric hydraulic driving system which is provided with an electric motor (10) and a fluid pump (12), the fluid pump can be driven by the electric motor (10) through a driven shaft (14), the driven shaft is provided with a rotor (16), and the rotor can be guided in a mode of rotating in a stator (18) surrounded by a shell (22) of the electric motor (10). The utility model relates to a fluid pump (10) having a motor housing (22) and having a pump housing (24), characterized in that a damping mass (26) is inserted between the motor housing (22) and the pump housing (24) in order to reduce noise emissions, which damping mass is made of a metal material in a solid structure and through which the driven shaft (14) passes, the output shaft is guided in the damping mass (26) in a bearing point (28) which is completely surrounded by the damping mass (26) and which is supported directly on the damping mass with its bearing bush.

Description

Technical Field

[0001] The utility model relates to an electro-hydraulic drive system, which has an electric motor and a fluid pump. The fluid pump can be driven by the electric motor via a driven shaft. The driven shaft has a rotor, and the rotor is guided in a stator surrounded by the housing of the electric motor in a rotatable manner. And the fluid pump has a pump housing. Background Art

[0002] An engine-pump unit known from EP2921703A2 as a related drive system has an electric motor and a reversible internal gear machine. The internal gear machine has a multi-piece housing, in which a pinion with external teeth and a ring gear with internal teeth are arranged. A free space is formed between the mentioned gears, and a multi-piece filling member is arranged in the free space. The filling member includes a plurality of radially movable radial seal segments, and a radial gap is formed between the radial seal segments. An axially movable axial seal plate is arranged between the axial end faces of the gears and the housing components of the housing. The axial seal plate has a seal plate control groove that can be loaded with a pressure medium in an open manner towards the end face of the gear. The seal plate control groove faces the radial gap and is directly opposed to it. The pinion segment and / or the ring gear segment have a laterally extending radial seal segment control channel that can be loaded with a pressure medium. The radial seal segment control channel faces the radial gap and directly leads into the radial gap.

[0003] When continuously transitioning to so-called electric mobility, the internal combustion engine is additionally replaced by an electric synchronous motor. And here, the hydrostatic drive device for the travel drive device of the working machine and the drive device for the associated working hydraulic mechanism are both operated by the relevant synchronous motor. The internal combustion engine is currently the main parameter in terms of vehicle noise formation. And through the transition to electric drive components, the fluid or hydraulic pump has now become an increasingly determining factor for the noise level of vehicles equipped with such a drive system. Therefore, although the electric drive device operates extremely quietly, additional components (such as fluid pumps) are now those that cause annoying noises. Summary of the Utility Model

[0004] Therefore, starting from this prior art, the task of the utility model is to provide an electro-hydraulic drive system, all of whose components exhibit low noise. A drive system according to the utility model solves the relevant task as a whole.

[0005] In the following manner, i.e., a damping block is inserted between the motor housing and the pump housing for reducing noise emissions. The damping block is made of a metallic material in a solid structure and is penetrated by the driven shaft. The driven shaft is guided in the damping block at a bearing location, and the bearing location is completely surrounded by the damping block and its bearing bush is directly supported on the damping block, thereby achieving a significant and continuous reduction in the noise level of the entire drive system. The mentioned damping block corresponding to the solid structure and especially made of steel material forms effective radial and axial noise for reducing noise, and the related layout structure fully meets the specific noise requirements for a drive system with a synchronous engine, and the synchronous engine serves as a primary noise damper to replace the noisy internal combustion engine in this regard. In particular, a part of the bearing noise during the operation of the driven shaft is directly introduced into the damping block. What is unexpected for those skilled in the art of such drive systems is that the drive system solution according to the present invention achieves a largely noise-free operation, especially because a metallic material is used for noise damping instead of the otherwise common elastomeric materials such as rubber.

[0006] Since there is an effective isolation between the hydraulic components and the electrical components of the drive system through the damping block, fluid decoupling between the hydraulic unit and the electrical unit is also achieved. Because there is always a certain degree of contamination and water content in the operating fluid when using hydraulic devices (here within the scope of operating a fluid pump), at least short-circuit-proof operation for the motor is achieved through the mentioned decoupling. In addition, by separating the hydraulic mechanism and the electrical mechanism, improved cooling can be achieved for each of these components.

[0007] Furthermore, it is found that there is a modular structure for the entire drive system together with its components, including the motor and the fluid pump, such that the drive system itself can be adapted to changing power requirements without problems, for example, if a larger displacement is required. Even in relevant cases, the damping block still achieves a noise value exceeding the acceptable level for the entire drive system. The damping block can especially be used as a standardizable basic component, and then a very large number of types of motors and fluid pumps can be connected to the basic component on the opposite side of the damping block. Therefore, there is no equivalent in the prior art.

[0008] In a preferred embodiment of the electro-hydraulic drive system, it has been proven advantageous here that the damping block is constructed as a prism facing the environment, preferably in the form of a hexagonal prism, and particularly preferably in the form of an octagonal prism. The related prismatic construction results in a plurality of refracting edges, on which the noise occurring during operation can be refracted correspondingly, which leads to a significant reduction in noise emissions.

[0009] In a further particularly preferred embodiment of the electrohydraulic drive system according to the present utility model, it is provided that the driven shaft has a coupling portion in a free end region thereof for connecting the drive shaft of the fluid pump, the coupling portion is surrounded by the damping block, and the bearing portion for the driven shaft and the coupling portion for the drive shaft of the fluid pump are introduced into the damping block on opposite end faces of the damping block. By accommodating the coupling portion in the damping block, vibrations occurring during the operation of the shaft are correspondingly damped, and such vibrations may also cause noise emissions.

[0010] In a further preferred embodiment of the electrohydraulic drive system according to the present utility model, it is provided that the damping block is penetrated by a separate fluid guide for introducing and discharging fluid, such as a hydraulic medium or a cooling medium, and the fluid exerts a damping effect when passing through the damping block. In addition to the additional damping effect, a short path for introducing and discharging the hydraulic medium and / or the cooling medium is generated in this way, which has proven to be energy - favorable for the drive system as a whole.

[0011] From the perspective of vibration technology and thus proven to be low - noise: when viewed in the direction of the driven shaft, the axial structural length of the damping block substantially corresponds to the axial structural length of the pump housing of the fluid pump.

[0012] In a further preferred embodiment of the electrohydraulic drive system, it is provided that the driven shaft is supported via additional bearing portions, the additional bearing portions are received in a cover member of the electric motor in an end region opposite to the bearing portion, and the cover member closes the electric motor on the side of the electric motor facing away from the damping block. Preferably, one of the bearing portions for the driven shaft is integrated in a hood - shaped cover member of the motor housing and the additional bearing portion is integrated in a closed portion formed by the damping block. In this way, reliable reception of longitudinal and lateral forces on the driven shaft of the electric motor is achieved by means of the respective bearing portions. Here, only two bearing portions in total are sufficient for reliable support and a kind of "floating support". By means of the relevant bearing portion arrangement structure having a bearing portion in the damping block and an additional bearing portion in the hood - shaped cover member, the respective bearing portions are shielded from the environment and a low - noise drive for the fluid pump via the driven shaft of the electric motor can be ensured (even in the region of the bearing portions). In particular, bending vibrations of the driven shaft are avoided, and more precisely, by supporting the roller of the pump at the point of action of the generated force.

[0013] It has proven particularly advantageous that the end walls of the motor housing and the end walls of the pump housing rest flush against each other on the mutually opposing end faces of the device damping block, such that possible vibrations are introduced into the damping block from both sides, and the damping block thus occupies the central position for the entire drive system for damping purposes. Additionally, installation aids provided centrally via the damping block are also realized for the safe assembly of the entire drive system together with its various components.

[0014] It has also proven advantageous for good damping that the outer diameter of the motor housing is selected to be larger than the outer diameter of the pump housing, such that good support for the pump is achieved via the motor housing, which is damping in this regard, even during its operation.

[0015] In another particularly preferred embodiment of the electro-hydraulic drive system, it is provided that the damping block tapers conically in the direction of the receiving portion in the motor housing at the support portion, and the damping block and the adjacent conical wall portion of the motor define a funnel-shaped acoustic chamber. Due to the funnel-shaped acoustic chamber, possible sound waves can be damped in a targeted manner and thus noise emissions can be prevented.

[0016] In another preferred embodiment of the electro-hydraulic drive system, it is provided that the damping block is embodied in the form of a support structure, and the motor housing and the pump housing are connected to the support structure thus formed on the opposing sides. In this way, within the broad scope outlined, the drive system according to the present invention can also be used retrospectively on almost any working machine of the hydraulic system, and possible noise-generating vibrations of the drive system as a whole can be directed in a targeted manner via the support foot portions into the base, such as the machine base, etc.

[0017] For the electro-hydraulic drive system, it can preferably be provided that, during reverse operation, the fluid pump then serves as a hydraulic motor, which drives the motor to generate electricity during generator operation. In this way, 4-quadrant operation can be achieved, such that the pump assumes the function of the hydraulic motor and the synchronous motor serves as the generator for power generation. It is particularly advantageous that the drive system allows the two operating possibilities mentioned above in a combined manner in terms of the design of its components, such that various applications during the operation of a movable working machine can be covered using only one structural unit.

[0018] The fluid pump is preferably a swashplate machine, in which the respective delivery pistons are supported at one end on a fixed swashplate, and the respective delivery pistons are successively guided from respectively different piston positions for performing the pumping movement in piston chambers of the housing part that can be jointly guided in a rotationally fixed manner by means of a driven shaft, in an axial movement direction parallel to the longitudinal axis of the driven shaft. The use of a swashplate machine or an axial piston machine has proven to be functionally reliable, since the respective delivery pistons are guided with low friction in the fluid of the assigned piston chamber of the pump housing part for their respective axial pumping movement. However, external gear pumps and internal gear pumps can also be used without problems as fluid pumps, and although there is gear meshing, these pumps do not tend to emit noise strongly during operation in principle.

[0019] The housing part having the respective piston chambers and the accommodated delivery pistons can be preloaded in the direction of the swashplate by means of an energy store, which is preferably in the form of a compression spring. By means of the mentioned energy store, tolerances during the operation of the fluid pump can be compensated, but in particular the energy store is used to ensure contact between the drum and the control mirror at any position of the pump in the chamber during non-pressurized operation.

[0020] Alternatively, instead of a one-piece driven shaft, it can be provided that the driven shaft and an independent drive shaft of the fluid pump are coupled to each other via a coupling, such as a spline shaft tooth part. In this way, simple assembly of the entire drive system is achieved, and the fluid pump can be removed from the damping block and the driven shaft guided therein together with its drive shaft in a simple manner for maintenance or repair purposes. In this way, it is also possible to simply replace an old fluid pump with a new one.

[0021] If the driven shaft is preferably led out through an axially arranged through-opening on the free end face of the pump housing and a coupling part led out from the pump housing is carried on its free end, which is preferably configured as another spline shaft tooth part for coupling a third component, such as another fluid pump, then within the scope of the overall delivery concept, the pump power for the drive system can be further increased in a low-noise manner by connecting together a plurality of fluid pumps. Description of the Drawings

[0022] The electro-hydraulic drive system according to the present invention will be explained in detail below with reference to the embodiments according to the drawings. Figure 1 A longitudinal sectional view of the main components of such a drive system is shown in a schematic diagram. Detailed Description of the Embodiment

[0023] In Figure 1The electrohydraulic drive system shown as a whole has an electric motor 10 and a fluid pump 12, which can be driven by the electric motor 10 via a driven shaft 14. The driven shaft 14 has a rotor 16, which is guided in a stator 18 with a coil winding 20 in a manner common for electric motors 10 and can rotate therein. The stator 18, or rather the coil winding 20, is surrounded by a cylindrical housing 22 of the electric motor 10.

[0024] To reduce any type of noise emission, a solid, metallic damping block 26 is inserted between the motor housing 22 and the pump housing 24. The damping block is completely penetrated by the driven shaft 14, which is guided in a bearing section 28 in the damping block 26. The damping block 26 is constructed substantially hollow-cylindrically for the driven shaft 14 to pass through. As can be further deduced from Figure 1 it, when viewed in the direction of the longitudinal axis 30 of the driven shaft 14, the axial structural length of the damping block 26 is approximately as large as the axial structural length of the pump housing 24 in the same orientation as the longitudinal axis 30. In particular, the motor housing 22, the pump housing 24, and the damping block 26 are arranged concentrically with the longitudinal axis 30. In particular, the hollow damping block 26 is constructed towards the environment as a prism with a plurality of refracting edges.

[0025] The end wall 32 of the motor housing 22 and the end wall 34 of the pump housing 24 both abut flush on the mutually opposite end faces 36 or 38 of the damping block 26. For this purpose, a step 40 with a reduced diameter is introduced in the end wall 36 of the damping block 26, which is lapped by the cylindrical end region of the motor housing 22 at this location. In addition, a circumferential wall extension 42 protruding in the direction of the rotor 16 is introduced in the relevant end face 36, which accommodates the bearing section 28. Conversely, the flatly extending end wall 34 of the pump housing 24 is fixedly arranged in a releasable manner, for example, fixedly screwed, on the opposite end face 38 of the damping block 26. In this regard, the damping block 26 forms a bearing cover or connecting plate for the entire device.

[0026] To advantageously introduce vibrations while providing the corresponding damping effect, it has proven advantageous that the outer diameter of the motor housing 22 is selected to be larger than the outer diameter of the pump housing 24, and the outer diameter of the damping block 26 lies between the mentioned outer diameters.

[0027] The driven shaft 14 is supported later via a further bearing section 44, which is accommodated in a hood-shaped cover part 46 of the electric motor 10 in the end region opposite the bearing section 28. The cover part hermetically seals the electric motor 10 against the environment on the side opposite the damping block 26.

[0028] The wall extension 42 is configured to taper conically in the direction of the longitudinal axis 30 of the driven shaft 14 and, together with the adjacent portions of the coil winding 20, defines a funnel-shaped acoustic chamber 48 which is adapted to direct possible sound emissions of the fluid pump 12 towards the intermediate receiving chamber 50 for the driven shaft 14; the chamber 50 is acoustically insulated from the environment by the housing 22 and the stator 18. Here, it is also advantageous that the intermediate receiving chamber 50 opens at its other end into a further acoustic chamber 52 having a taper and a spatial "capacity" corresponding to that of the first acoustic chamber 48, which results in another damping possibility for possible "accumulated" sound waves in the intermediate receiving chamber 50.

[0029] As Figure 1 Further shown, this further acoustic chamber 52 extends in the direction of the hollow cylindrical cover member 56 with a further support portion 44. As shown, the cover member 46 is fixedly but detachably connected to the circumferential outer periphery of the housing 22 and has two through portions on the outer wall side for an electrical connection 54 in the form of two supply lines between the coil winding 20 and a power supply (not shown in detail).

[0030] Furthermore, when viewed in the direction towards Figure 1 the lower side of the damping block 26 has tab-shaped downwardly projecting support means 56 by means of which the drive system as a whole can be supported or fixed on the foot side to a third member (not shown), such as a machine component. In this way, noise emissions caused by vibrations can also be effectively conducted via the support means 56 with a damping effect into the connected machine component. As shown, the damping block 26 can be penetrated by channels or openings 58 for the introduction and discharge of the pump fluid of the fluid pump 12, which pump fluid also exerts a damping effect when periodically flowing through the damping block 26 in the form of a hydraulic medium. In this way, coolant can also be supplied (which is not shown in detail) to the electric motor 10 within the operating range of the electric motor 10. In this way, coolant supply for the fluid pump 12 can also be achieved. Since the support member 56 forms an interface for the support of the pump 12 and the electric motor 10, a balanced support is achieved, which has also proven to be advantageous in suppressing sound emissions.

[0031] Now, the structure of the fluid pump 12 will be explained in detail below. In this embodiment, the fluid pump is designed as a so-called swashplate machine. Many structural forms of relevant fluid pumps can be found in the prior art (for example, through DE102013008678A1), such that the fluid pump 12 will only be described in outline to the extent necessary for understanding the present utility model. In Figure 1The axial piston pump with the swashplate structure type shown in the figure has a swashplate 60 which is fixedly arranged in the pump housing 24 and held in position by means of at least one barrel pin 62. Since the swashplate 60 is immovable in this embodiment, different from that in DE102013008678A1, a constant pump with a constant delivery volume is thus realized as a fluid pump 12. In addition, the fluid pump 12 has a cylindrical pump housing part 64 which can be rotationally connected to the driven shaft 14 by means of a spline shaft tooth part 66 and can be rotationally driven by the driven shaft. Here, the associated outer peripheral surface can be rotationally guided in the pump housing 24 along the third support part 71.

[0032] As shown in the cross-section above the longitudinal axis 30 in Figure 1 , a separate piston chamber 68 is introduced into the housing part 64, in which a separate assigned delivery piston 70 can be guided longitudinally. For simplicity, in Figure 1 , only one piston chamber 68 with the assigned delivery piston 70 is shown, and a plurality of such delivery pistons 70 are distributed around the driven shaft 14 concentrically around the longitudinal axis 30 at the same spacing from each other. Due to the inclination of the swashplate 60, the shown delivery piston 70 is in its lowest fluid-displacing delivery position, while on the side diametrically opposite to the longitudinal axis 30 of the driven shaft 14, a delivery piston is accommodated in the housing part 64 in its uppermost position, where the maximum possible delivery volume of the fluid pump 12 occurs in the assigned piston chamber 68. In the lowest set position, as shown for the upper delivery piston 70, the relevant amount of fluid accommodated is pushed out of the pump housing part 64 again during the pumping operation for supply to a hydraulic consumer (not shown in detail), such as a working cylinder.

[0033] The delivery pistons for fluid suction and fluid discharge respectively are connected to the corresponding fluid inlet and outlet pipelines with the respective piston bottoms of their each piston chamber 68. The fluid inlet and outlet pipelines are omitted in Figure 1 for simplicity and for a clearer view. In addition to introducing and discharging fluid via the channels 58 in the damping block 26, there is also the possibility that, when needed, relevant pipelines can be installed via the exposed outer end face of the pump housing 24 and the pump 12 can thus be connected to a supply circuit (not shown).

[0034] Due to the splined shaft tooth portion 66 mentioned, the pump housing part 64 can be guided to move on the driven shaft 14 coaxially with the longitudinal axis 30, and due to the energy storage device in the form of a compression spring 72, the housing part 64 is preloaded in the direction of the swash plate 72 via its respective delivery pistons 70 by means of an additional abutment sleeve 74. Here, the compression spring 72 supports with one of its free ends on the relevant abutment sleeve 74 in the direction of the swash plate 60 and with its other free end on the housing-side receiving chamber of the pump housing part 64 facing the splined shaft tooth portion 66.

[0035] According to Figure 1 the driven shaft 14 is integrally constructed and opens into another splined shaft tooth portion 76 at one of its free ends. The one-piece driven shaft 14 led out of the pump housing 24 via an axially arranged through-opening 77 at the end side is guided via two bearing sites 28 and 44, which are held in position in a conventional manner by locking rings and can be formed by bearings of a conventional construction type, for example by ball bearings. However, separate bearing sites can also be replaced by bearing bushes, not shown in detail, having good sliding properties. If the driven shaft 14 projects with its other splined shaft tooth portion 76 beyond the end face wall of the pump housing 24, a seal 78 is formed at this location by a narrowing in the swash plate 60. However, in an embodiment not shown in detail, in the case of using only one fluid pump 12, the projection having the other splined shaft tooth portion 76 described can also be omitted and in this respect the pump housing 24 would be provided with a seal on its freely outwardly arranged end face by means of an end cover.

[0036] With the drive system according to Figure 1 the present invention, so-called reverse or four-quadrant operation can also be achieved, in which the fluid pump 12 acts as a hydraulic motor and the driven shaft 14 subsequently driven from the fluid pump 12 side generates a changing electric field in the stator 18 via its rotor 16, such that the electric motor 10 now generates an electric current in generator operation, which can be output in a conventional manner via the electrical connection part 54 to an electrical consumer (not shown). Instead of the fluid pump 12 of the swash plate construction type, other fluid pumps not shown in detail, for example fluid pumps in the form of internal and / or external gear machines, can also be used. Finally, however, in the present solution, the delivery pistons 70 are guided within the piston chambers 68 and are thus encapsulated in these piston chambers, which helps to reduce noise.

[0037] The converted electro-hydraulic power results from the drive speed and the pressure in the working line of the output fluid, not shown in detail, plus the possible leakage volume flow, which is led out of the pump housing 24 via at least one separate leakage connection 80, the leakage connection according to Figure 1As shown in , it is closed by a plug before being put into use. All the components used in the drive system are preferably designed in a solid structure, which particularly applies to the solid damping block 26, so that a low-noise characteristic during operation is achieved due to the very rigid structure. If necessary, further measures can be taken to reduce noise, such as using additional damping inserts (not shown) in the housings 22 and 24.

Claims

1. An electro-hydraulic drive system having an electric motor (10) and a fluid pump (12), the fluid pump being drivable by the electric motor (10) via a driven shaft (14) having a rotor (16) which is guided for rotation in a stator (18) surrounded by a motor housing (22) of the electric motor (10), and the fluid pump having a pump housing (24), characterized in that, A damping block (26) is inserted between the motor housing (22) and the pump housing (24) to reduce noise emissions. The damping block is made of a metallic material in a solid structure and is penetrated by the driven shaft (14). The driven shaft is guided in the damping block (26) in a bearing portion (28), which is completely surrounded by the damping block (26) and whose bearing bush directly bears on the damping block.

2. The electro-hydraulic drive system according to claim 1, characterized in that The damping block (26) forms a prism towards the environment.

3. The electro-hydraulic drive system according to claim 2, characterized in that, The prism is in the form of a hexahedron prism.

4. The electro-hydraulic drive system according to claim 2, characterized in that, The prism is in the form of an octahedron prism.

5. The electro-hydraulic drive system according to any one of claims 1 to 4, characterized in that, The driven shaft (14) has a coupling portion on its free end region for connecting to the drive shaft of the fluid pump (12). The coupling portion is surrounded by the damping block (26), and the bearing portion (28) for the driven shaft (14) and the coupling portion for the drive shaft of the fluid pump (12) are introduced into the damping block in opposite end faces of the damping block (26).

6. The electro-hydraulic drive system according to any one of claims 1 to 4, characterized in that The damping block (26) is penetrated by a separate fluid guide (58) for introducing and discharging fluid, and the fluid exerts a damping effect when flowing through the damping block (26).

7. The electro-hydraulic drive system according to claim 6, characterized in that, The fluid is a hydraulic medium or a cooling medium.

8. The electro-hydraulic drive system according to any one of claims 1 to 4, characterized in that, Viewed in the direction of the driven shaft (14), the axial structural length of the damping block (26) approximately corresponds to the axial structural length of the pump housing (24) of the fluid pump (12).

9. The electro-hydraulic drive system according to any one of claims 1 to 4, characterized in that, The driven shaft (14) is supported via another bearing portion (44), which is received in a cover member (46) of the motor (10) in the end region opposite to the bearing portion (28). The cover member closes the motor (10) on the side of the motor facing away from the damping block (26).

10. The electro-hydraulic drive system according to any one of claims 1 to 4, characterized in that The end wall (32) of the motor housing (22) and the end wall (34) of the pump housing (24) both abut flush on opposite end faces (36, 38) of the damping block (26).

11. The electro-hydraulic drive system according to any one of claims 1 to 4, characterized in that, The outer diameter of the motor housing (22) is selected to be larger than the outer diameter of the pump housing (24).

12. The electro-hydraulic drive system according to any one of claims 1 to 4, characterized in that, The damping block (26) tapers conically towards the direction of the receiving portion in the motor housing (22) in the bearing portion (28), and together with the adjacent conical wall portion of the motor (10), the damping block defines a funnel-shaped acoustic chamber (48).

13. The electro-hydraulic drive system according to any one of claims 1 to 4, characterized in that The damping block (26) is implemented in a support structure, and the motor housing (22) and the pump housing (24) are connected to a support (56) configured in this way on the opposite sides.

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