Lubricant supply system for a motor vehicle and pump for such a lubricant supply system

Abstract

The invention relates to a lubricant supply system for a motor vehicle and a pump for such a lubricant supply system. The lubricant supply system (44) comprises a dry sump (46), an oil tank (48), and a pump (2) for pumping oil (50) from the dry sump (46) into the oil tank (48) and for conveying the oil (50) out of the oil tank (48). The pump (2) comprises a housing (4), a drive shaft (14) extending in an axial direction (10), and at least three pump units (26, 28) arranged together on the drive shaft (14) in a row in the axial direction (10). The three pump units (26, 28) are each designed as a cycloidal rotor. This achieves a simple, compact, and inexpensive design.

Description

Technical Field

[0001] The present invention relates to a lubricant supply system for a motor vehicle and a pump for such a lubricant supply system. The lubricant supply system includes a dry sump, an oil tank, and a pump configured to transfer oil from the dry sump to the oil tank and also to pump the oil from the oil tank to components of the motor vehicle to be supplied. To this end, the pump includes a drive shaft and at least three pump units, which are arranged axially one behind the other on the drive shaft. Background Art

[0002] In the present context, whenever a lubricant supply system is mentioned, it should be understood as a closed system in which a lubricant circulates. Within the scope of this application, the lubricant is referred to as oil, but is not limited to oil. The oil (lubricant) is used to reduce friction in moving parts of a vehicle and / or to cool vehicle components.

[0003] Such supply systems are known, for example, from DE 10 2019 201 864 A1 and DE 10 2019 208 845 A1. In DE 10 2019 208 845 A1, the individual pump units are designed as external gear pump units. In particular, a multi-acting external gear pump is provided, in which a total of three gears mesh with one another, forming two pump stages. These two pump stages are therefore arranged transversely to the drive shaft, which drives the gears.

[0004] DE 10 2019 201 864 A1 discloses a pump having three pump units arranged on a common shaft. One of the pump units is designed as a two-stage vane pump. The third pump unit is designed as a cycloid rotor, which feeds oil to the vane pump via a branch on the delivery side in order to preload the vane pump with pressure and thus improve its starting behavior. Summary of the Invention

[0005] Based on this, the object of the present invention is to enable an improved design of such a lubricant supply system.

[0006] According to the invention, this object is solved by a lubricant supply system having the features of the invention and by a pump having the features of the invention for such a lubricant supply system. The advantages and preferred designs listed below regarding the lubricant supply system can also be adapted to the pump.

[0007] A lubricant supply system, installed in a motor vehicle, comprises a dry sump, an oil tank, and a pump for pumping oil from the dry sump into the oil tank and also for pumping oil from the oil tank to components in the motor vehicle to be supplied. In particular, the supply is provided to a plurality of components. For example, these components are oil-lubricated transmissions. Alternatively, and particularly in addition, this may involve an electric machine, such as an electric traction motor, or other components of the electric drive train in a hybrid or electric vehicle, in order to cool these components, in particular.

[0008] A pump typically has a motor, in particular an electric motor, having a motor shaft, which forms the drive shaft. The pump has at least three, and preferably exactly three, pump units, which are arranged together on the drive shaft. According to the present invention, each of the three pump units is designed as a cycloid rotor, that is, each pump unit is designed as a cycloid pump unit. The three cycloid pump units, and thus the pump stages, are arranged one behind the other on the drive shaft in the axial direction defined by the drive shaft, more precisely, in close proximity to one another.

[0009] The structure of cycloidal rotors is well known. These usually have a rotor set (gear set) with an outer ring with internal gearing (outer ring gear) and an inner rotor with external gearing (inner ring gear). The inner rotor is driven and runs eccentrically inside the outer ring.

[0010] A particular advantage of using a cycloidal rotor is the simple adjustment and scalability of the pumping capacity to different pump units. Therefore, it is often necessary for the suction capacity of the pump for extracting oil from a dry sump to be greater than the pumping capacity of the pressure pump unit used to convey the oil from the oil tank to the components being supplied. With a cycloidal rotor, the pumping capacity can be easily scaled and adjusted by appropriately selecting and adjusting the axial extension along the drive shaft.

[0011] In particular, it is thus possible for all gerotor pump units to have the same diameter, which preferably differ only in their axial extent.

[0012] Accordingly, in a preferred embodiment, the three pump units each have the same diameter, but at least two pump units differ in their axial length. In particular, the three pump units each have the same cross-sectional profile, i.e., the cross-sectional profiles of the rotor assembly are identical, i.e., the cross-sectional profiles of the inner rotor and outer ring of the different pump units are identical. They differ only in their axial length.

[0013] In particular, it is provided that two of the pump units are designed as suction pumps, which are preferably identical in terms of the cross-sectional geometry of their rotor groups and their axial length. The third pump unit is preferably designed as a pressure pump, which differs from the other two suction pumps (preferably only) in its axial length.

[0014] This results in lower costs, as identical components can be used for the various parts of the cycloid rotor. Due to the identical cross-sectional profile, the typically disk-shaped ring gear of the cycloid rotor's gear set can be adapted to various desired axial lengths, for example by cutting it to length from an extruded profile. The various components are thus provided according to the universal part principle and, in particular, manufactured from a standardized, common extruded profile. This results in a particularly cost-effective design.

[0015] A pump typically has a motor section with a motor, particularly an electric motor. Furthermore, the pump has a pump section with three pump units. In a preferred embodiment, the motor section is externally connected to the oil tank via a flange, and the pump section projects into the oil tank. The pump section is thus immersed directly into the oil in the oil tank. This has the particular advantage of at least partially avoiding the need for a sealed passage through the wall of the oil tank.

[0016] As already mentioned above, it is provided in particular that exactly two pump units are designed as suction pumps for conveying oil from the dry sump into the oil tank, and one of the pump units is designed as a pressure pump for conveying oil from the oil tank to at least one component to be supplied.

[0017] Furthermore, in a preferred embodiment, at least three pump units are directly connected to the oil tank via openings in the pump housing. This is understood to mean that openings, such as slots, are formed directly in the housing, which lead into the interior of the oil tank and, during operation, are also immersed in the oil in the oil tank. In particular, these openings are the two suction openings of the respective suction pump and the delivery opening of the delivery pump.

[0018] The openings are preferably formed by slots or grooves extending in the radial direction in a partition wall between two adjacent pump units or at the ends of the pump units (for example in the housing cover or the central part).

[0019] In a suitable development, the housing is multi-part and comprises a common housing part for both pump units, thereby enabling reliable and simple assembly with the smallest possible number of parts.

[0020] In particular, it is provided here that the common housing part (seen in half cross section) is T-shaped and has overall a central partition wall for separating the two pump units.

[0021] The common housing part with a T-shaped geometry as seen in a half cross section is preferably open to both end sides. The end sides of the common housing part are preferably delimited by a cover part or a partition wall.

[0022] In a particularly advantageous design, precisely one pump unit, in particular a pressure-feed pump, is connected to the drive shaft in the axial direction via a press fit, in particular an interference fit. In contrast, the other two pump units are arranged on the drive shaft with a clearance fit to allow axial displacement. This allows for reliable assembly, as the clearance fit can compensate for component tolerances. At the same time, the axial press fit provides axial blocking of all three pump units.

[0023] In order to achieve both a press fit and a clearance fit, a suitable design provides for the drive shaft to have a step in the axial direction, meaning that the drive shaft has different cross-sections and, in particular, different diameters. This establishes the principle of universal components for the rotor and extends it particularly to the externally toothed inner rotor of a cycloidal rotor. Thus, the corresponding bores are identical for all inner rotors driven by the drive shaft. The clearance fit is achieved by reducing the cross-section of the drive shaft.

[0024] Two pump units with clearance fit are clamped in the axial direction relative to the pump unit of press fit.This is realized especially by means of screws, which clamp the housing cover of the end side of the pump unit relative to the motor part in which the screws are screwed.

[0025] In a preferred development, for torque transmission, it is provided that the drive shaft has a flattened portion at least on one side and preferably on two opposite sides. Accordingly, the inner contour of the hole of the respective inner rotor is also provided with a flattened portion.

[0026] In order to design the desired clearance fit and press fit, it is particularly provided that the remaining partially cylindrical circumferential surface of the drive shaft is taken into account. This means that an interference fit is formed between the remaining partially cylindrical circumferential surface of the drive shaft and the inner rotor of one pump unit (the delivery pump). In contrast, only a clearance fit exists with the other two pump units (the suction pumps).

[0027] In a preferred embodiment, the drive shaft is supported on both sides of at least three pump units. Preferably, bearings are provided only at the opposite ends of the structural unit formed by the three pump units. The bearings can optionally be sliding bearings or rolling bearings. A larger bearing spacing is advantageous in order to, for example, avoid or at least reduce shaft tilting, which can occur in the event of tolerance-related positioning deviations in the bearings. By using only two bearings, the number of components is kept low overall and the total length is kept as low as possible. Therefore, the drive shaft is preferably not further supported within the three pump units. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The embodiments of the present invention will be explained in more detail below with reference to the accompanying drawings.

[0029] Figure 1 showing a perspective view of the pump;

[0030] Figure 2 Show the basis Figure 1 Front view of the pump;

[0031] Figure 3 Show the basis Figure 2 Section view along section line AA;

[0032] Figure 4 Show the basis Figure 2 Sectional view along section line BB;

[0033] Figure 5 Show the basis Figure 2 Cross-sectional view along section line CC;

[0034] Figure 6 Show the basis Figure 2 Sectional view along section line DD;

[0035] Figure 7 A detailed view showing an electric drive motor having a drive shaft;

[0036] Figure 8 based on Figure 6 A diagram showing a rotor assembly of three cycloid rotors plugged onto a drive shaft; and

[0037] Figure 9 Schematic diagram showing a lubricant supply system with a dry sump, oil tank and pump.

[0038] In the figures, parts having the same function are provided with the same reference numerals. DETAILED DESCRIPTION

[0039] The pump 2 shown in the figures generally has a housing 4, which is in particular constructed in multiple parts. In the exemplary embodiment, the pump 2 has an approximately L-shaped geometry as a whole.

[0040] However, the actual components of the pump 2, namely the motor part 6 and the pump part 8, extend in the axial direction 10 and are arranged one behind the other. The motor part 6 has a motor 12, typically designed as an electric motor, which drives a drive shaft 14. The motor 12 is arranged in a motor housing 16. The drive shaft 14 leads out of the motor housing 16 and through the pump part 8.

[0041] The housing 4 is designed as a whole in multiple parts and has further housing parts in addition to the motor housing 16. The housing thus has, in particular, a common housing part 22 and a housing cover 24 at its front end facing away from the motor part 6.

[0042] The pump part 8 is fastened to the motor part 6 by means of screws. For this purpose, the screws are passed from the housing cover 24 at the end, in particular through the common housing part 22, and screwed into the motor housing 16. The housing cover 24 thus clamps the common housing part 22 relative to the motor housing 16 via the screws.

[0043] A total of three pump units are arranged within the pump section 8: a delivery pump 26 and two suction pumps 28. Each of these pump units is designed as a cycloid pump unit. Therefore, each of these pump units has a gear set, namely an inner rotor 30 and an inner geared outer ring 32.

[0044] As can be seen from the cross-sectional views, the individual components of the different gear sets have the same diameter and are therefore common parts, at least in terms of their cross-sectional geometry. Figures 3 to 6 As can be seen from the cross-sectional view of FIG, the gear set of the pressure pump 26 has a smaller axial length than the respective gear set of the suction pump 28.

[0045] As especially from Figure 3 It can be seen that the common housing part 22 for the two suction pumps 28 is designed approximately T-shaped when viewed in half cross section, with a partition wall 33 being formed between the two gear sets, which separates the different chambers of the two suction pumps 28 from each other. This common housing part 22 is open at each end. It is bounded at the front by the housing cover 24 and at the rear by a cover-like middle part 35.

[0046] In the exemplary embodiment, the gear train of the pressure pump 26 is accommodated by a socket-shaped extension of the motor housing 16 and is delimited at the end in the axial direction 10 by a center section 35. The center section 35 thus separates the pump chamber of the pressure pump 26 from the pump chamber of the subsequent suction pump 28.

[0047] Each of the suction pumps 28 is connected via an opening in the housing 4 to the volume surrounding the pump section 8. Figure 3It can be seen that radially oriented gaps or grooves, referred to as feed gaps 34, are introduced in particular at the two opposite end regions of the second housing part 22, which are connected to the corresponding feed chambers of the cycloid rotor gear set. Figure 3 It can be seen that two feed slots 34 are each formed between the second housing part 22 and the housing cover 24 or the intermediate part 35. The feed slots 34 are in particular designed as radially outwardly directed grooves in the cover part 24 or in the intermediate part 35. The oil can escape directly from the respective feed chamber of the feed pump 26 via these feed slots 34.

[0048] Furthermore, the two press-feed slots 34 are preferably arranged at the same position in the circumferential direction.

[0049] Moreover, as especially from the Figure 5 As can be seen from the sectional view CC of , a suction gap 36 is also constructed for the pressure pump in a similar manner. This suction gap is in turn formed by a radially extending groove at the end between the middle part 35 and the motor housing 16. Preferably, the groove is constructed in the middle part 35.

[0050] The two suction pumps 28 are each assigned a suction line 38 , 40 extending in the axial direction 10 , which exits the housing cover 24 at the end face (see in particular Figure 1 、 Figure 2 and Figure 4 、 Figure 5 A pressure feed line 42, preferably extending in the axial direction 10, is connected to the pressure feed pump 26. Further suction or pressure feed lines, via which the oil is sucked or pumped, are connected to these lines 38, 40, 42. The suction lines 38, 40 and the pressure feed line 42 are each formed by a dedicated housing section.

[0051] As especially according to Figure 7 and Figure 8 It can be seen that the drive shaft 14 is provided with flats 43, in particular on opposite sides. The individual gear sets, in particular the individual inner rotors 30, are pushed onto the drive shaft 14. The flats 43 provide a rotationally fixed fastening, thereby achieving a torque drive and driving the respective inner rotor 30 via the drive shaft 14 during operation. Figure 7 It can also be seen that the drive shaft 14 has a slightly larger diameter in the region of the first inner rotor 30 of the feed pump 26 and therefore has a small shoulder further along. In this region, the inner rotor 30 is pressed onto the remaining partially cylindrical outer circumference, thereby forming a press fit that secures the inner rotor 30 in the axial direction 10. In contrast, the other two inner rotors 30 of the two suction pumps 28 are mounted on the drive shaft 14 with play.

[0052] according to Figure 9 A lubricant supply system 44 is shown. It comprises a dry sump 46, an oil tank 48, and the aforementioned pump 2. The lubricant supply system 44 has further components not shown in greater detail. These components include, in particular, suction hoses or lines, through which oil 50 is drawn from the dry sump 46 at various locations by means of two suction pumps 28 and pumped into the oil tank 48. The oil leaves the pump 2 via the pressure feed gap 34. Simultaneously, the pressure feed pump 26 draws oil from the oil tank 48 via the suction gap 36 and directs it via the pressure feed line 42 and further pressure feed hoses or lines (not shown in further detail) to the components to be supplied.

[0053] The oil tank 48 is preferably oriented vertically. The pump 2 is fastened on the outside to the wall 52 of the oil tank 48 with the motor part 6, in particular by a flange connection. At the same time, the pump part 8 enters the interior of the oil tank 48 and sinks into the oil 50 located there.

[0054] The present invention is not limited to the above-described embodiments. On the contrary, other variants of the present invention can also be derived therefrom by a person skilled in the art without departing from the subject matter of the present invention. In particular, all individual features associated with the embodiments can also be combined with one another in other ways without departing from the subject matter of the present invention.

[0055] Reference Signs List

[0056] 2 pumps

[0057] 4 Housing

[0058] 6 Motor part

[0059] 8 Pump section

[0060] 10 Axial direction

[0061] 12 motors

[0062] 14 drive shaft

[0063] 16 Motor housing

[0064] 18 Pump housing

[0065] 22 Common housing parts

[0066] 24 Housing cover

[0067] 26 Pressure pump

[0068] 28 Suction pump

[0069] 30 inner rotor

[0070] 32 outer ring

[0071] 33 partition wall

[0072] 34 Pressure feeding gap

[0073] 35 middle part

[0074] 36 Suction gap

[0075] 38 Suction line

[0076] 40 Suction line

[0077] 42 pressure feed line

[0078] 43 flat part

[0079] 44 Lubricant supply system

[0080] 46 Dry sump

[0081] 48 fuel tanks

[0082] 50 oil

[0083] 52 wall

Claims

1. A lubricant supply system (44) for a motor vehicle, the lubricant supply system comprising: - dry sump (46), - fuel tank (48), a pump (2) for pumping oil (50) from the dry sump (46) into the oil tank (48) and for conveying oil (50) out of the oil tank (48), wherein: The pump (2) comprises a housing (4), a drive shaft (14) extending in an axial direction (10), and at least three pump units (26, 28), It is characterized by: The three pump units (26, 28) are each constructed as a cycloid rotor arranged one after another on the drive shaft (14) in the axial direction (10). The pump (2) comprises a motor part (6) with a motor (12) and with the drive shaft (14), and a pump part (8) with the three pump units (26, 28), wherein the motor part (6) is externally connected to the oil tank (48) via a flange, and the pump part (8) projects into the oil tank (48). The three pump units (26, 28) are directly connected to the oil tank (48) via openings (34, 36) in the housing (4) of the pump (2). The two pump units (26, 28) are designed as suction pumps (28) for conveying oil (50) from the dry sump into the oil tank (48), and the two suction pumps (28) are each assigned a suction line (38, 40) extending in the axial direction (10) and exiting the housing cover (24) at the end side.

2. The lubricant supply system (44) according to claim 1, characterized in that The three pump units (26, 28) each have the same diameter, but at least two of the pump units (26, 28) have different lengths in the axial direction (10).

3. The lubricant supply system (44) according to any one of claims 1-2, characterized in that One of the pump units (26, 28) is designed as a pressure pump (26) for conveying oil (50) from the oil tank (48) to at least one component to be supplied.

4. The lubricant supply system (44) of claim 3, wherein: The openings are formed by slits or slots extending in the radial direction.

5. The lubricant supply system (44) according to any one of claims 1-2, characterized in that The housing (4) is multi-part and comprises a common housing part (22) for two pump units (26, 28) therein.

6. The lubricant supply system (44) according to claim 5, characterized in that The common housing part (22) is T-shaped when viewed in half cross section and has a central partition wall for separating the two pump units (26, 28).

7. The lubricant supply system (44) according to any one of claims 1-2, characterized in that One of the pump units (26, 28) is fixedly connected to the drive shaft (14) in the axial direction (10), and the other two pump units (28) are arranged on the drive shaft (14) with a clearance fit for axial displacement.

8. The lubricant supply system (44) according to any one of claims 1-2, characterized in that The drive shaft (14) has steps in the axial direction (10), so that the drive shaft has different diameters.

9. The lubricant supply system (44) according to any one of claims 1-2, characterized in that The drive shaft (14) has, at least on one side, a flat portion (43) for transmitting torque to the respective pump unit (26, 28).

10. The lubricant supply system (44) according to any one of claims 1-2, characterized in that The drive shaft (14) is cylindrical except for at least one flat portion, and an interference fit is formed between the cylindrical circumference of the drive shaft (14) and one of the pump units (26), while a clearance fit is formed between the cylindrical circumference of the drive shaft and the other two pump units (28).

11. The lubricant supply system (44) according to any one of claims 1-2, characterized in that The drive shaft (14) is supported on both sides of the at least three pump units (26, 28).

12. The lubricant supply system (44) according to claim 7, characterized in that One of the pump units is a pressure-feed pump (26).

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