Drive assembly for motor vehicle

Abstract

The invention relates to a drive assembly for a motor vehicle, comprising a housing with a housing cover forming a terminal axial section of the housing, and an electric machine arranged in the housing with a stator fastened to the housing and a rotor arranged radially in the stator and fastened to a rotor shaft, the housing cover having a connecting piece extending inward in the axial direction, a housing cover, which supports a rotor shaft bearing that rotatably supports the rotor shaft and forms a receiving space between the rotor shaft bearing and the axial closing wall of the housing cover, which receiving space accommodates an axial end of the rotor shaft, which rotor shaft is hollow and through which oil can flow, and which has at least one radial channel adjacent to the rotor shaft bearing, the rotor shaft can be thrown from the interior of the rotor shaft to the axial end region of the stator in a manner that the rotor shaft can be propelled by centrifugal force during operation of the drive assembly. The invention is characterized in that the rotor shaft end is surrounded by a flange which is fixed to the housing and is a component of the rotational position sensor, said flange carrying the temperature sensor at the lowest point of the inner wall thereof.

Description

Technical Field

[0001] The invention relates to a drive assembly for a motor vehicle, comprising:

[0002] a housing with a housing cover forming a terminal axial section of the housing, and

[0003] an electric machine arranged in a housing, the electric machine having a stator fixed to the housing and a rotor arranged in the stator and fixed to a rotor shaft,

[0004] The housing cover has a connecting piece extending inwardly in the axial direction, which supports a rotor shaft bearing for rotatably supporting the rotor shaft and forms a receiving space between the rotor shaft bearing and an axially closed wall (abschlusswand, sometimes referred to as an end wall) of the housing cover, which receives the axial end of the rotor shaft.

[0005] The rotor shaft is hollow and oil can flow through it and has at least one radial channel adjacent to the rotor shaft bearing, through which the oil can be flung from the interior of the rotor shaft to the axial end region of the stator during operation of the drive assembly by centrifugal force. Background Art

[0006] Such a drive assembly is known from DE 10 2016 204 980 A1.

[0007] This document discloses an electric traction machine for a motor vehicle, which has a hollow rotor shaft, the hollow interior of which serves as an oil-conducting channel. During operation, oil is introduced into the cavity of the rotor shaft on one side and flows through it in the axial direction, wherein the oil is subjected to corresponding centrifugal forces due to the rotation of the rotor shaft. In those areas of the rotor shaft which coincide axially with the end areas of the stator, in particular its so-called winding heads, the rotor shaft carries radial openings through which the oil can penetrate outward from the interior of the rotor shaft and in particular be thrown out radially due to the centrifugal forces mentioned. This results in cooling and wetting of the winding heads. In order to lubricate the rotor shaft bearings, additional radial channels are provided in the rotor shaft in the direct vicinity of the rotor shaft bearings, which are covered by deflection plates fixed to the rotor shaft, so that the oil conveyed outward through the additional radial channels is deflected in the axial direction from its radial throwing direction caused by the centrifugal forces to the rotor shaft bearings. The rotor shaft bearing is fixed in a connecting piece formed by the housing cover, which connecting piece furthermore defines a free space, referred to here as a receiving space, between the rotor shaft bearing and the axially closing wall of the housing cover, in which the rotor shaft end ends, that is, the rotor shaft end (i.e., the axial end of the rotor shaft) protrudes into this free space. The oil that penetrates the rotor shaft bearing to lubricate it also flows into the receiving space. In the lower region of the receiving space in the final assembly position, the receiving space is open, that is, the wall of the connecting piece has an opening here, so that the rotor shaft lubricating oil can flow out into the oil sump. There, the rotor shaft lubricating oil again combines with the stator cooling oil that drips from the winding head and is guided to the oil sump in another way.

[0008] Depending on the driving situation, very different mechanical and electrical conditions exist in electric vehicle drives, both of which greatly influence the thermal state of the components involved, in particular the rotor shaft bearings and the winding head. In order to ensure optimal operation and in any case avoid damage caused by thermal overload, it is advantageous to obtain information about the thermal state of the relevant components. However, the above-mentioned document does not contain any disclosure in this regard.

[0009] In principle, the use of temperature sensors is obviously known. From DE 101 41 930 B4, a combined rotational speed and temperature sensor is even known. However, this combined sensor cannot be combined with a drive assembly of the type described above due to its special design. Summary of the invention

[0010] The object of the present invention is to improve a drive assembly of this type in such a way that meaningful information can be obtained about the thermal state of components that are particularly stressed electrically and mechanically, namely in particular the winding heads of the stator and the rotor shaft bearings.

[0011] This object is achieved in conjunction with the features described at the outset in that the rotor shaft end is surrounded by a collar which is fixed to the housing and is a component of the rotational position sensor and which carries the temperature sensor at the lowest point of its inner wall.

[0012] Rotational position sensors for determining the rotational position of a shaft are generally known and are often also used to measure the rotational position of a rotor shaft in an electric traction machine of a motor vehicle. They usually include a stationary flange, in particular fixed to the housing, which surrounds a transmitter wheel (Geberrad, sometimes called a transducer wheel) which is connected to the end of the rotor shaft in a rotationally fixed manner (drehfest, sometimes called anti-rotationally). An electrical signal representing the rotational position of the transmitter wheel and thus the rotational position of the rotor shaft can be generated by electromagnetic interaction between the transmitter wheel or the electronic components arranged in the transmitter wheel and the electronic components arranged in the flange. Such a rotational position sensor can be designed as a resolver, an inductive rotational position transmitter (Drehlagegeber, sometimes called a rotational position transducer) or in a manner that works according to another principle.

[0013] According to the invention, such a rotational position sensor is combined with a separate temperature sensor in such a way that the latter is arranged at the lowest point of the inner wall of the flange in the final state of assembly. This results in that the oil that enters the flange and flows out at its inner wall driven by gravity must flow past the temperature sensor, which can detect the temperature of the flowing oil. Since the flange surrounds the axial end of the hollow rotor shaft as described above, at least the oil flowing through the hollow rotor shaft must reach the flange when leaving the rotor shaft. In particular, it can be assumed that the oil is thrown outwards at the edge of the shaft driven by centrifugal force and is intercepted by the mentioned flange. As provided in a preferred embodiment of the invention, this principle can be further supported in that the rotational position sensor has an impeller fixed to the rotor shaft in a rotationally fixed manner, spanning its open end, in particular as its transmitter wheel. On the one hand, such an impeller is suitable for generating a periodic electrical signal in a manner that interacts with the electronic components in the flange when rotating; on the other hand, the impeller forms a sufficient passage to allow the oil to flow out of the hollow interior of the rotor shaft.

[0014] Although the oil leaving the rotor shaft does not flow directly through the rotor shaft bearings, it flows in the interior of the rotor shaft in the direct vicinity of the rotor shaft bearings (in unmittelbarer Nachbarschaft, sometimes referred to as nearby), so that the oil can be considered representative for the thermal state of the rotor shaft bearings without any problems.

[0015] In a preferred development of the invention, it is provided that the oil flowing out of the winding head is also included in the temperature measurement, the temperature of this oil representing the thermal state of the winding head. For this purpose, the aforementioned development provides that the housing cover has an oil guide structure, by means of which the oil flowing out of the upper region of the stator can be guided through the perforations of the connecting pipe, that is, through the passage in its wall to the aforementioned flange of the rotary position sensor. In this embodiment, therefore, the oil axially leaving the rotor shaft on the one hand and the oil flowing out of the winding head on the other hand are collected in the receiving space and in particular in the flange of the rotary position sensor, so that the temperature sensor detects the temperature of this oil mixture. Although no distinction is made according to different sources of the oil in this embodiment, it has proven to be sufficient for evaluating the overall thermal condition.

[0016] After the temperature measurement, the oil is in the receiving space. Of course, the oil must be discharged from there. For this purpose, a preferred embodiment of the invention provides that the connecting piece has an oil outflow opening in the lower area of ​​its wall on the side of the rotor shaft bearing facing away from the receiving space. This oil outflow opening cannot be identical to the axial end opening of the connecting piece. In any case, the arrangement of the opening on the other side of the rotor shaft bearing means that the oil can only flow out if the oil has previously passed through the rotor shaft bearing and lubricated it there.

[0017] The oil guide, by means of which the oil flowing out of the winding head can be supplied to the flange and in particular to the temperature sensor, preferably comprises a horizontal plate with a funnel-like profile that projects above the connecting piece into the interior of the housing. The vertical passages of this horizontal plate are preferably co-located with the perforations of the connecting piece in the horizontal direction and / or are connected to the perforations via pipes. In this way, the oil dripping from the winding head can be intercepted over a large area and directed by gravity into the relatively small passages in the wall of the connecting piece. This then also facilitates the further guidance of the oil within the connecting piece, i.e. into the flange.

[0018] Although the rotary position sensor and the temperature sensor are in principle separate sensor elements and in particular have different sensor heads operating according to different principles, they can preferably have a common electronic control. It is particularly advantageous if the measured values ​​of the rotary position sensor and the temperature sensor can be tapped via a common contact plug. In particular, the rotary position sensor (at least its flange) and the temperature sensor together with the electronic control and the common contact plug can be designed as a continuous ( Sometimes referred to as an interconnected) module that can be used or removed as a single component. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Further features and advantages of the present invention emerge from the following detailed description and the accompanying drawings.

[0020] in:

[0021] Figure 1 A highly schematic cross-sectional view of a drive assembly according to the invention is shown. DETAILED DESCRIPTION

[0022] Figure 1 1 shows a highly schematic cross-sectional view of a drive assembly 10 according to the invention. The drive assembly has a housing 12, the axial end section of which (at Figure 1 The housing cover 120 is referred to here as the housing cover 120. The term component "cover" is to be understood only as an indication of its nature as an axial end section of the housing 12 and does not mean additional information about detachability or a flat design, although this is entirely possible with the housing cover 120 according to the invention.

[0023] An electric motor 14 is arranged in the housing 12. The electric motor comprises a stator 141 fixed to the housing, the axial end section of which is referred to herein as a winding head 142. The winding head 142 is generally a region in which the conductor winding of the stator is deflected axially. A rotor 143 is arranged radially in the stator 141. The lamination stack of the rotor is fixed to a rotor shaft 144, which is rotatably supported in the housing 12. Figure 1 Only the bearing point, namely the rotor shaft bearing 16 in the housing cover 120 , is shown.

[0024] Specifically, the rotor shaft bearing 16 is fixed to the inner wall of a connecting piece 18, which extends tubularly axially inward (with respect to the housing 12) from an axially closure wall 121 of a housing cover 120. The rotor shaft 144 extends into the connecting piece 18 and ends in a receiving space 20 formed between the rotor shaft bearing 16 and the axially closure wall 121 of the housing.

[0025] The rotor shaft 144 is designed to be hollow. The rotor shaft end of the rotor shaft that protrudes into the receiving space 20 is provided with an impeller 22, which acts as a transmitter wheel of a rotational position sensor that is not presented in detail otherwise. In addition to the impeller 22, the rotational position sensor also has a flange surrounding the rotor shaft end, which flange contains electronic components that generate an electrical signal representing the rotational position of the latter and therefore the rotational position of the rotor shaft 143 in a manner that interacts with the transmitter wheel. In the presented, extremely simplified embodiment, the connecting pipe 18 itself serves as the flange of the rotational position sensor. In other embodiments, it is conceivable to design the flange as a separate component that is fixed to the connecting pipe 18.

[0026] The flange (in the embodiment shown, the connection pipe 18 itself) is located at the Figure 1 The temperature sensor 24 is located at the lowest position in the final assembly position shown in FIG.

[0027] Arranged above the connection piece 18 is a horizontal plate 26 which is preferably funnel-shaped and has a vertical passage 261 . This passage is located exactly above the perforation 181 in the upper side of the connection piece 18 .

[0028] When the drive assembly according to the invention is in operation, the rotor shaft 144 rotates together with the rotor 143 in the stator 141. In this case, the oil (which flows in Figure 1 The oil (indicated by arrows in the figure) is guided in the axial direction through the hollow rotor shaft 144. The origin of the oil and the specific conveying mechanism are irrelevant in the context of the present invention. The rotor shaft 144 has a radial channel 145 adjacent to the axial end of the rotor 143, through which the oil is thrown onto the winding head 142 by centrifugal force. The oil that is not guided out through the radial channel 145 passes through the impeller 22 and leaves from the end of the rotor shaft 144 into the receiving space 20. The oil flowing out from the upper area of ​​the winding head is intercepted by the horizontal plate 26 and is also guided into the receiving space 20 via the passage 261 of the horizontal plate and the perforation 181 in the upper area of ​​the connecting pipe 18. Here, the oils from the two sources are mixed and pass through the temperature sensor 24, which thus measures the corresponding mixed temperature.

[0029] The oil collected in the receiving space 20 flows out through the rotor shaft bearing 16 and is guided to the oil sump along a path not shown in detail. In the embodiment shown, this path leads through the lower region of the winding head 142, which in this way experiences additional cooling.

[0030] Of course, the embodiments discussed in the detailed description and shown in the figures are merely illustrative examples of the present invention. Based on the disclosure herein, a person skilled in the art is provided with a wide range of variation possibilities. It is particularly conceivable that the oil dripping from the winding head 142 is prevented from being supplied to the accommodation space 20, in particular by closing the perforation 181 in the connecting pipe 18 or the passage 261 in the horizontal plate 26. In such a design, the temperature sensor 24 only measures the temperature of the oil leaving the rotor shaft 144. The temperature of the oil dripping from the winding head 142 can be measured using a separate temperature sensor on the outside of the connecting pipe 18 or in the area of ​​the horizontal plate 26. Such an additional temperature sensor can form a structural unit in terms of measurement technology together with the temperature sensor 24 arranged in the accommodation space 20 and preferably also with the rotational position sensor.

[0031] Reference Numbers List

[0032] 10. Drive Components

[0033] 12 Housing

[0034] 120 Housing cover

[0035] 121 120 axially closed wall

[0036] 14 Motor

[0037] 141 Stator

[0038] 142 Winding head

[0039] 143 Rotor

[0040] 144 rotor shaft

[0041] 145 Radial channel

[0042] 16 Rotor shaft bearing

[0043] 18 Takeover

[0044] 181 18 piercing

[0045] 20 Accommodation Space

[0046] 22 Impeller

[0047] 24 Temperature Sensor

[0048] 26 Horizontal panels

[0049] 261 26's passage

Claims

1. A drive assembly (10) for a motor vehicle, comprising: - a housing (12) with a housing cover (121) forming a terminal axial section of said housing (12), and an electric motor (14) arranged in the housing (12), the electric motor having a stator (141) fixed to the housing and a rotor (143) arranged radially inside the stator (141) and fixed to a rotor shaft (144), The housing cover (121) has a connecting pipe (18) extending inwardly in the axial direction, the connecting pipe carries a rotor shaft bearing (16) for rotatably supporting the rotor shaft (144) and forms a receiving space (20) between the rotor shaft bearing and an axially closed wall (121) of the housing cover (120), the receiving space receiving the axial end of the rotor shaft (144), The rotor shaft (144) is hollow and oil can flow through it and has at least one radial channel (145) adjacent to the rotor shaft bearing (16), through which the oil can be flung from the interior of the rotor shaft (144) to the axial end region of the stator (141) during operation of the drive assembly (10) by centrifugal force. It is characterized in that The rotor shaft end is surrounded by a flange which is fixed to the housing and is a component of a rotational position sensor and carries a temperature sensor (24) at the lowest point of its inner wall.

2. The drive assembly (10) according to claim 1, It is characterized in that The housing cover (120) has an oil guide structure, by means of which oil flowing out of the upper region of the stator (141) can be guided through a through-hole (181) of the connecting piece (18) into the aforementioned collar.

3. A drive assembly (10) according to any one of the preceding claims, It is characterized in that The connecting piece (18) has an oil outlet opening in the lower region of its wall on the side of the rotor shaft bearing (16) facing away from the receiving space (20).

4. Drive assembly (10) according to any one of the preceding claims, It is characterized in that The rotational position sensor has as a further component an encoder wheel which is connected in a rotationally fixed manner to the rotor shaft end, wherein an electrical signal representing the rotational position of the encoder wheel can be generated by electromagnetic interaction between the encoder wheel and electronic components arranged in the flange.

5. Drive assembly (10) according to any one of the preceding claims, It is characterized in that The rotational position sensor and the temperature sensor (24) have a common electronic control device.

6. Drive assembly (10) according to any one of the preceding claims, It is characterized in that The measured values ​​of the rotational position sensor and the temperature sensor (24) can be tapped off via a common contact plug.

7. Drive assembly (10) according to any one of the preceding claims, It is characterized in that The rotational position sensor is designed as a resolver or as an inductive rotational position transmitter.

8. Drive assembly (10) according to any one of the preceding claims, It is characterized in that The rotary position sensor has an impeller (22) which is fixed in a rotationally fixed manner on the rotor shaft (144) and extends across its open end.

9. Drive assembly (10) according to any one of the preceding claims, It is characterized in that The oil guide structure comprises a horizontal plate (26) with a funnel-shaped profile which projects above the connecting piece (18) into the interior of the housing (12).

10. The drive assembly (10) according to claim 9, It is characterized in that The vertical passage (26) of the horizontal plate (261) is co-located with the perforation (181) of the connecting pipe (18) in the horizontal direction and / or is connected to the perforation via a pipe.

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