Oil distribution system used to distribute oil in a car drive

Abstract

The present invention relates to an oil distribution system (10) for distributing oil in an automotive drive system having an electric motor with a stator and a rotor rotatably supported relative to the stator on a hollow rotor shaft (18), the oil distribution system including an oil tank and a delivery device (14) for conveying oil from the oil tank to a plurality of oil distribution channels (16, 16'), at least one of the oil distribution channels being a first oil distribution channel (16) transitioning in the oil flow direction to a curved oil guide (20), the oil guide extending near a conductive rail (22) connected to the motor and opening axially into a first end of the hollow rotor shaft (18), wherein the oil guide (20) has a lateral nozzle (24) pointing towards the conductive rail (22) in its section near the conductive rail (22). The invention is characterized in that a spring-preloaded check valve (26) in the oil guide (20) is provided in the oil flow direction after the nozzle (24) and before the inlet to the rotor shaft (18), the check valve being spring-preloaded in the opposite direction to the oil flow direction.

Description

Technical Field

[0001] This invention relates to an oil distribution system for distributing oil in an automotive drive system, the system having an electric motor with a stator and a rotor rotatably supported relative to the stator on a hollow rotor shaft, the system including an oil tank and a delivery device for conveying oil from the oil tank to a plurality of oil distribution channels, at least one of the oil distribution channels transitioning in the oil flow direction to a curved guide tube extending near a conductive rail connected to the motor and axially entering a first end of the hollow rotor shaft, wherein the guide tube has a lateral nozzle pointing towards the conductive rail in its section near the conductive rail. Background Technology

[0002] This oil blending system is described in the unpublished German patent application DE 10 2021 202 837.3.

[0003] This document discloses an electric drive system for automobiles, designed as a compact drive unit comprising, on the one hand, the actual drive unit, i.e., an electric motor, and on the other hand, a transmission for transmitting and distributing the torque provided by the electric motor. Both units are arranged in a common housing, however, due to the different requirements of each unit, the housing is divided into substantially separate spaces: a motor compartment and a transmission compartment. Both spaces are traversed by a common shaft, which serves specifically as the rotor shaft of the electric motor in the motor compartment. It is supported on the one hand in an inner end wall separating the motor compartment from the transmission compartment, and on the other hand in an outer end wall opposite the inner end wall at another axial end of the motor compartment. The rotor shaft extends through the inner end wall into the transmission compartment, where it carries the transmission input wheel. The rotor shaft extends through the outer end wall into a cover compartment, which will be discussed in more detail later.

[0004] The transmission input wheel holds oil in the oil pan in the lower region of the transmission. As the input wheel rotates, it carries oil from the oil pan and throws it into an oil collector located in the upper region of the transmission compartment. The oil collector has multiple outlets at different heights, and external distribution channels connect to these outlets to distribute the collected oil to different cooling and lubrication locations of the drive according to a priority specified by the outlet height. A special cooling location exists within the hollow rotor shaft. One distribution channel from the oil collector extends into the axial end of the rotor shaft (referred to as the second end in the context of this specification), causing the oil flowing through it to accumulate inside the rotor shaft, where a cooling effect is achieved. From a defined level, the oil is thrown out again through the rotor shaft outlets, particularly to structures in contact with the motor stator requiring cooling, and then flows back into the oil pan.

[0005] However, the gears that hold oil in the oil pan and the associated oil collector are not the only components of such a conveying device described in the previous application. The conveying device also includes an oil pump that draws oil from a side region of the oil pan and directs it to other lubrication and cooling locations via further distribution channels. One of these distribution channels, connected to the oil pump, transitions at its distal end to an oil guide tube that delivers oil to the other end of the hollow rotor shaft, referred to in the context of this application as the first end. The rotor shaft is supported by the first end on an outer end wall of the motor housing opposite the aforementioned inner end wall, allowing the first end to penetrate the outer end wall and thus be accessible from an axially adjacent cover chamber. Within the cover chamber, the oil guide tube extends in an arc shape, ultimately flowing into the first end of the rotor shaft. However, prior to this, it is adjacent to conductive rails protruding into the cover chamber, through which power is supplied to the motor. Due to the high current flowing here, these conductive rails require significant cooling. Therefore, the oil guide tube has nozzles pointing towards the conductive rails where they pass. When there is sufficient oil pressure in the oil guide tube, the conductive rail can be wetted by the cooling oil from the oil guide tube. Only the portion of the oil that does not leave the oil guide tube through the nozzle is fed into the first axial end of the rotor shaft, where it mixes with the oil supplied through the second end.

[0006] The problem here is the imprecise definition of conductor rail cooling. The amount of oil output through the nozzles depends on the prevailing oil pressure in the oil conduit. This, in turn, depends heavily on the current oil supply, which can fluctuate dramatically due to driving conditions. This is particularly true in situations where the oil distribution channel of the supply line is not connected to a regularly operating pump, but is instead supplied from a collector via a gearbox. In any case, the overall oil pressure is generally relatively low, so in individual cases, the prevailing pressure in the oil conduit is also heavily dependent on manufacturing tolerances. This makes the supply of cooling oil to the conductor rail unpredictable and uncontrollable. However, reliable, essentially constant cooling of the conductor rail improves the efficiency of the electric drive. Summary of the Invention

[0007] The technical problem to be solved by this invention is to further develop such an oil distribution system in order to achieve more reliable and constant cooling of the conductive rail.

[0008] The technical problem is solved by an oil distribution system for distributing oil in an automotive drive system, the system having a motor with a stator and a rotor rotatably supported relative to the stator on a hollow rotor shaft. The oil distribution system includes an oil tank and a conveying device for conveying oil from the oil tank to a plurality of oil distribution channels. At least one of the oil distribution channels, a first oil distribution channel, transitions in the oil flow direction to a curved guide tube extending near a conductive rail connected to the motor and axially entering a first end of the hollow rotor shaft. The guide tube has a lateral nozzle pointing towards the conductive rail in its section near the conductive rail. The system is characterized by a spring-preloaded check valve in the oil distribution channel, following the nozzle and preceding the inlet to the rotor shaft, in the direction of oil flow.

[0009] The basic concept of this invention lies in the purposeful use of a check valve in the oil guide tube, to a certain extent, as a booster or pressure maintainer. The typical function of a check valve is to allow fluid to flow in a first direction and prevent it from flowing in the opposite second direction. However, in this case, it is impossible to reverse the flow direction of the oil in the oil guide tube, so the primary purpose of the check valve used in this invention cannot be applied here. However, this invention utilizes a secondary, generally undesirable property of the spring-preloaded check valve in ordinary applications: the blocking effect in the upstream region of the valve, and the cumulative effect of the valve in current-intensive regions. As long as the oil pressure upstream of the valve is less than the spring force of the spring preload mechanism locking the valve, the valve remains closed—even though the oil flow direction is "correct." Therefore, with further oil delivery, the upstream oil pressure increases. This is used according to the invention to create a constant pressure condition at the nozzle, thereby ensuring continuous wetting and cooling of the conductive rail. Once the oil pressure rises above the limit defined by the spring force of the check valve (despite pressure loss at the nozzle), the check valve opens. However, this can only be maintained to such an extent or for such a long time until the upstream oil pressure falls below the aforementioned limit pressure, after which it is rapidly rebuilt or increased due to further oil delivery. Therefore, the cooling of the oil rails is uniform. This comes at the cost of repeatedly interrupting the injection of oil into the first end of the rotor shaft. However, this is largely insignificant because, as mentioned above, the rotor shaft is supplied with cooling oil through a second source (i.e., an oil distribution channel leading to its second axial end). Therefore, the unevenness of the oil supply to the rotor shaft via the guide pipe is not important; rather, the uniformity of the oil supply to the guide rails brings significant efficiency advantages.

[0010] Through the optimized design of this system, it can be ensured that, except under conditions of very weak operation of the delivery device, such as when the oil pump rotates very slowly, such as during startup, there is always sufficient pressure around the oil guide pipe to ensure the opening of the check valve, thereby guaranteeing the oil supply to the rotor shaft. Typically, only about 10% of the volumetric flow rate reaches the conductive rail through the nozzle. According to the invention, this proportion is ensured to be constant in almost all driving conditions. On the other hand, a larger share delivered to the rotor shaft depends on the delivery power, such as the rotational speed of the oil pump.

[0011] Preferably, the check valve includes

[0012] -valve housing,

[0013] - An axially movable valve body within the valve housing, the valve body having an outer diameter smaller than the inner diameter of the valve housing.

[0014] - A support wall that extends radially into the inner chamber of the valve body.

[0015] - A bore wall, arranged upstream of the support wall along the oil flow direction, having at least one through hole, reducing the net cross-section of the valve body, and

[0016] - A compression spring, which is supported on one side of the support wall and on the other side of the valve body arranged between the support wall and the bore wall, is used to press the valve body against the bore wall in a manner that closes the through hole of the bore wall when the oil pressure generated upstream of the check valve is lower than the limit pressure defined by the spring force of the compression spring.

[0017] The valve body can be part of the guide tube itself. However, it is also conceivable that a separate element, particularly one with an increased diameter compared to the guide tube, is placed within the guide tube. The support wall or bore wall can be a wall separately introduced into the valve body. In particular, in the case described above where the separate valve body introduced into the guide tube has an increased diameter, its axial end wall can also serve as a bore wall, forming a transition between the smaller diameter of the guide tube and the larger diameter of the valve body.

[0018] For the check valve according to the invention to function reliably, it is advantageous for the valve body to move only axially as much as possible. In a preferred embodiment, the valve body thus has radially extending cantilever arms, which slidably support the valve body against the inner wall of the valve housing. Because the cantilever arms are designed with sufficiently fine filaments, they do not substantially impede the flow of oil around the central portion of the valve body.

[0019] Alternatively, the valve body may be specified to have radially inward-pointing, axially extending guide ribs, with the valve body slidably supported on the radially inner edge region of the guide ribs. Specifically, the valve body itself may be specified to be slidably supported on the radially inner edge of the guide ribs. This design creates the lowest possible total frictional contact between the guide ribs and the valve body. Alternatively or supplementarily, the guide ribs may be arranged such that the valve body (always on the edge region) is slidably supported on the sides of the guide ribs, in which case the guide ribs do not extend precisely radially inward, but rather offset from the corresponding radial lateral direction.

[0020] The central portion of the valve body is preferably spherical or bolt-shaped. This optimizes the flow around the valve.

[0021] However, alternatively, the central portion of the valve body can be designed as a plate. This variation has the advantage that larger through-holes in the bore wall can be covered within the same axial structural space.

[0022] To achieve permanent guidance of the compression spring, in the extended design of the invention, a cylindrical push rod, surrounded by a compression spring preferably designed as a helical spring, is formed on the central body in the downstream direction of the fluid and is slidably supported in a bearing hole in the support wall. The push rod serves both for radial fixation of the helical spring and for guiding the valve body. Attached Figure Description

[0023] Further details and advantages of the present invention will become apparent from the following detailed description and accompanying drawings:

[0024] In the attached diagram:

[0025] Figure 1 A schematic top view of the oil guide pipe area of ​​the oil distribution system according to the present invention is shown.

[0026] Figure 2 This diagram illustrates the principle of the oil mixing system of the present invention.

[0027] Figure 3 A first embodiment of a check valve used within the scope of this invention is shown.

[0028] Figure 4 A second embodiment of the check valve used within the scope of this invention is shown.

[0029] Figure 5 A third embodiment of the check valve used within the scope of this invention is shown.

[0030] Figure 6 A fourth embodiment of a check valve used within the scope of this invention is shown, and

[0031] Figure 7 A fourth embodiment of a check valve used within the scope of this invention is shown. Detailed Implementation

[0032] The same reference numerals in the accompanying drawings denote the same or similar elements.

[0033] Figure 1 A very schematic view shows relevant portions of the oil mixing system 10 according to the invention, which in... Figure 2 The schematic diagram is shown in the figure. Oil is transported from the oil pan 12 to each oil distribution channel through the conveying device 14. Figure 2 Only two of the oil distribution channels, namely oil distribution channels 16 and 16', are shown. The delivery device 14 can be designed as an oil pump. However, alternatively or supplementarily, it can also be formed in another way, for example as an oil collector, which is filled by gears that hold oil in the oil sump 12 and flows into the oil distribution channels 16 and / or 16' by gravity. Hybrid embodiments of the delivery device 14 even correspond to preferred embodiments of the invention. On one hand, an active subsystem is provided in which oil is pumped into the oil distribution channel 16. On the other hand, a passive subsystem is provided in which oil is gravity-driven from the oil collector into the oil distribution channel 16'. Figure 2 The view should be interpreted in a broader sense accordingly. Figure 2 The lower oil distribution channel 16' leads to Figure 2 The hollow rotor shaft 18 of the motor is shown. Furthermore, an oil distribution passage, not shown, can guide (and will not be described in detail further) the vehicle's drive system.

[0034] Figure 2 The upper oil distribution channel 16 leads to the guide oil pipe 20, which in turn... Figure 1The diagram is schematic but shows more structural details. An oil guide tube 20 extends in an arc within a cover chamber, which is axially adjacent to the motor and through which the rotor shaft 18 passes. The axial end face of the rotor shaft 18 has a port opposite to the port into which the oil distribution passage 16' extends. The distal end 201 of the oil guide tube 20 opens into the rotor shaft port within the cover chamber. However, along the route from the oil distribution passage 16 to the port of the rotor shaft 18, the oil guide tube 20 arcs through the cover chamber, positioned near the conductive rail 22, which passes through the cover chamber and provides power to the motor. Due to the high current intensity, these conductive rails require special cooling. For this purpose, nozzles 24 are positioned accordingly within the oil guide tube 20, with their outlets pointing towards the conductive rail 22, so that oil is sprayed onto the conductive rail when there is sufficient oil pressure in the oil guide tube 20, for example, between 0.05 and 0.3 bar. To ensure sufficient and constant oil pressure in oil pipe 20 regardless of the current flow rate, a spring-loaded check valve 26 is integrated along the oil flow direction, after nozzle 24 and at the distal end of guide pipe 20. The spring preload force is opposite to the oil flow direction. As long as the oil pressure in guide pipe 20 is below the opening limit pressure of check valve 26, oil in guide pipe 20 is only delivered to conductive rail 22 through nozzle 24. When the limit pressure is reached, check valve 26 opens, keeping the injection of conductive rail 22 constant, but excess oil is delivered to rotor shaft through distal end 201 of guide pipe 20.

[0035] Figures 3 to 7 Various advantageous embodiments of the check valve 26 are shown, which in all embodiments preferably consists of two plastic half-shells 261, 262, which form the valve housing 28. Within the valve housing, an orifice wall 30 is arranged on the inlet side (in... Figures 3 to 7 The lower half of the valve housing 261 (on the left side), except for the central orifice plate 32, largely occupies the net cross-section of the valve housing 28. In the illustrated embodiment, the orifice wall 30 is fixed in the corresponding lower half 262 and embedded in the corresponding sealing groove 34 of the upper half 261. However, a complete seal is not required, and slight leakage is harmless to the principles of the invention. However, in another advantageous embodiment, the half 261, 262 may be at least partially, and particularly completely, sealed to each other, for example, by means of a material-jointed connection or by means of additional sealing elements.

[0036] Downstream of the orifice wall, a support wall 36, which in principle allows oil flow to bypass or pass through, is provided in the valve body 28. The support wall 36 primarily supports the compression spring 38, which in turn supports the valve body 40 and presses it against the orifice plate 32 of the orifice wall 30 in a closed manner. Figure 3 , Figure 4 and Figure 6 In one embodiment, the valve body 40 has a valve tappet, and the support wall 36 also serves as a sliding bearing for the tappet.

[0037] In embodiments 3 and 4, the functional portion of the valve body 40 is essentially designed as a plate. Figure 4 In one embodiment, a cantilever 42, which serves as a centering arm, is formed on a plate that interacts with the orifice plate 32. This cantilever slides on the wall of the valve body 28, thereby assisting in the centering support of the valve body 40.

[0038] exist Figure 5 , Figure 6 and Figure 7 In one embodiment, the actuating portion of the valve body 40 is designed to be substantially spherical. Figure 6 In one embodiment, a cantilever 42 serving as a centering arm is formed on a sphere of the valve body 40 that interacts with the orifice plate 32, as shown in the figure. Figure 4 In the context of the above, the sliding support is on the wall of the valve body 28.

[0039] Figure 7 In this embodiment, instead of the cantilever 42, axially extending guide ribs 44 are provided on the inner wall of the valve housing 28, with their edge regions serving to support the spherical valve body 40 therein. In the illustrated embodiment, the two central guide ribs 44 are precisely radially aligned such that their edges interact with the upper and lower vertices of the spherical valve body 40. On the other hand, two lateral guide ribs 44 are arranged parallel to the vertical direction such that their sides near their edges serve to laterally guide the valve body 40.

[0040] All the embodiments shown can be inexpensively made of a few parts and are essentially made of plastic.

[0041] Of course, the embodiments discussed in the detailed description and the embodiments shown in the figures are merely illustrative embodiments of the present invention. Those skilled in the art will be able to derive a wide range of possible modifications based on the disclosure herein.

[0042] List of reference numerals

[0043] 10. Oil Distribution System

[0044] 12 Oil pan

[0045] 14 Conveying device

[0046] 16 Oil distribution channel

[0047] 16' Oil distribution channel

[0048] 18 Rotor shaft

[0049] 20 Oil guide pipe

[0050] 201 Distal end of oil guide tube 20

[0051] 22 conductive rails

[0052] 24 nozzles

[0053] 26 Check valve

[0054] 261 Upper half of check valve 26

[0055] 262 Lower half of check valve 26

[0056] 28 valve housing

[0057] 30-hole wall

[0058] 32 Through holes in the wall 30

[0059] 34 Sealing groove

[0060] 36 Supporting wall

[0061] 38 Compression Spring

[0062] 40 Valve body

[0063] 42 Cantilever

[0064] 44. Guide ribs.

Claims

1. A distribution system (10) for distributing oil in an automotive drive, the distribution system having an electric motor having a stator and a rotor rotatably supported relative to the stator on a hollow rotor shaft (18), the distribution system including an oil tank and a conveying device (14) for conveying oil from the oil tank to a plurality of distribution channels (16, 16'), at least one first distribution channel (16) of the distribution channels transitioning in the oil flow direction to a curved guide pipe (20), the guide pipe extending near a conductive rail (22) connected to the motor and opening axially into a first end of the hollow rotor shaft (18), wherein, The oil guide tube (20) has a lateral nozzle (24) pointing towards the conductive rail (22) in its section near the conductive rail (22), characterized in that a spring-loaded check valve (26) in the oil guide tube (20) is provided in the direction of oil flow after the nozzle (24) and before the inlet to the rotor shaft (18), wherein at least one second oil distribution channel (16') is introduced into the second end of the hollow rotor shaft (18) opposite to the first end.

2. The oil mixing system (10) according to claim 1, characterized in that, The delivery device (14) includes an oil pump and / or an oil collector, which is capable of being filled by a gear that holds oil in the oil pan (12) and has multiple outlets connected to at least some of the distribution channels (16, 16').

3. The oil mixing system (10) according to claim 1, characterized in that, The check valve (26) includes: - Valve housing (28), - A valve body (40) that is axially movable within the valve housing (28) has an outer diameter smaller than the inner diameter of the valve housing (28). - A support wall (36) extending radially into the inner chamber of the valve body (28), - A bore wall (30) arranged upstream of the support wall (36) along the oil flow direction, having at least one through hole (32), which reduces the net cross-section of the valve body, and - A compression spring (38), which is supported on the support wall (36) on one side and on the valve body (40) arranged between the support wall (36) and the bore wall (30) on the other side, is used to press the valve body against the bore wall (30) in such a way as to close the through hole (32) of the bore wall (30) when the oil pressure generated upstream of the check valve (26) is lower than the limit pressure defined by the spring force of the compression spring (38).

4. The oil mixing system (10) according to claim 3, characterized in that, The valve body (40) has a radially extending cantilever (42) which is slidably supported on the inner wall of the valve housing (28).

5. The oil mixing system (10) according to claim 3, characterized in that, The valve body (28) has radially inwardly pointing guide ribs (44) that extend longitudinally along the axial direction, and the valve body (40) is slidably supported on the radially inner edge region of the guide ribs (44).

6. The oil mixing system (10) according to claim 5, characterized in that, The valve body (40) is slidably supported on the radially inner edge of the guide rib (44).

7. The oil mixing system (10) according to claim 3, characterized in that, The working part of the valve body (40) is designed to be spherical or bolt-shaped.

8. The oil mixing system (10) according to claim 3, characterized in that, The working part of the valve body (40) is designed as a plate.

9. The oil mixing system (10) according to claim 7 or 8, characterized in that, A cylindrical push rod surrounded by a compression spring (38) is formed on the working part of the valve body (40) in the direction downstream of the fluid and is slidably supported in the bearing hole of the support wall (36).

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