Method for adjusting the oil level in an oil-cooled electric drive motor

Abstract

Method for adjusting an oil level in an oil-cooled electric drive machine (2), comprising the steps: - Draining (100) residual oil from the electric drive motor (2) via an oil draining device (4), - Filling (200) an initial quantity of oil via an oil filling agent (6), - Tempering (300) the oil to achieve a defined oil temperature range (T), - Continuous addition (400) of oil to the electric drive motor (2) within the defined oil temperature range (T) via an oil filling medium (6), until detection of an overflow of excess oil from an oil overflow (8).

Description

[0001] The present invention relates to a method for adjusting an oil level in an oil-cooled electric drive motor and to an oil-cooled electric drive motor for driving a drive train. Furthermore, the present invention relates to a motor vehicle comprising such an oil-cooled electric drive motor.

[0002] Oil-cooled electric drive motors are known from the state of the art, for example, from documents DE 10 2008 001 622 A1, DE 10 2013 226 851 A1, and CN 2 05 921 505 U. Typically, the drive motors are completely filled with cooling oil during production, so that the correct oil level or quantity is already present after production. The provision of a sensor to measure the cooling oil level is generally not provided.

[0003] If the oil level needs to be checked by customer service, e.g., after an oil change or repair, this is often difficult because the residual oil quantity can vary depending on the current temperature, the draining time, the number of disassembled parts, etc. Furthermore, when the machine is at a standstill, the volumes of an oil reservoir and the electric motor can communicate with each other via the gaps in the gear pump, making it impossible to clearly determine the current oil level.

[0004] It is therefore the object of the present invention to at least partially remedy the disadvantages described above, in particular it is the object of the present invention to provide a method for adjusting an oil level in an oil-cooled electric drive machine which enables the oil level to be adjusted as precisely as possible in a simple, quick and cost-effective manner.

[0005] The above object is achieved by a method having the features of claim 1, an oil-cooled electric drive motor according to claim 5, and a motor vehicle according to claim 12. Further features and details emerge from the subclaims, the description, and the drawings. Technical features disclosed for the method according to the invention also apply in connection with the oil-cooled electric drive motor and the motor vehicle according to the invention, and vice versa, so that with regard to the disclosure of the individual aspects of the invention, reference is always made to each other. Expedient embodiments of the invention are set forth in the dependent claims.

[0006] According to the invention, a method for adjusting an oil level in an oil-cooled electric drive motor is provided. The method according to the invention comprises the steps of draining residual oil from the electric drive motor via an oil draining means, filling an initial amount of oil via an oil filling means, tempering the oil to achieve a defined oil temperature range, and continuously adding oil to the electric drive motor within the defined oil temperature range via an oil filling means until excess oil is detected from an oil overflow.

[0007] According to the invention, a method for adjusting an oil level in an oil-cooled electric drive machine is provided, which method enables a particularly precise adjustment of an oil level in an oil-cooled electric drive machine in a simple, fast and cost-effective manner by the inventive combination of draining residual oil, filling an initial amount of oil and continuously supplying oil at a defined temperature until an overflow of excess oil is detected.

[0008] Compared to known methods for adjusting the oil level in an oil-cooled electric drive motor, this method is particularly distinguished by its precise determination of the oil level, which is primarily achieved by the fact that the correct setting of the oil quantity is structurally adapted to the height of an overflow. Since filling can take place at a defined oil temperature (e.g., 50 °C) by tempering the oil (e.g., by operating a conveying device such as an oil pump or using an oil-water heat exchanger), the oil's expansion coefficient is also compensated or taken into account during the setting.

[0009] The oil-cooled electric drive motor adjustable using the present method can preferably be used in an at least partially electrically powered motor vehicle, such as an at least partially electrically powered car or truck. However, use in other vehicles, such as commercial vehicles, ships, or aircraft, is also conceivable.

[0010] Within the scope of the invention, an oil level can preferably be understood as the amount or volume of oil within a cooling circuit of an oil-cooled electric drive motor. Residual oil can be understood in particular as the remaining part or a part of an oil residue remaining within a cooling circuit of an oil-cooled electric drive motor. Within the scope of the invention, an initial oil quantity can be understood in particular as a defined or definable first amount of added oil that is sufficient to generate a constant temperature within the electric drive motor, at least for a short time. A defined oil temperature range can, for example, be a temperature range between 45 and 50 °C, but also a narrower range, for example from 50.0 °C to 50.1 °C.Finally, an overflow of excess oil from an oil overflow can literally be understood as oil running out of a certain reservoir (especially the cooling circuit), which can be used to determine the exact amount of oil within a cooling circuit.

[0011] With a view to ensuring a simple, complete drainage of residual oil from an electric drive motor, it can advantageously be provided that the residual oil from the electric drive motor is drained from an oil reservoir, with the residual oil preferably being drained through an oil draining means arranged in the bottom of the oil reservoir. Such an arrangement makes it possible, in particular, to completely collect the oil still present within an oil cooling circuit in one location to ensure complete drainage.

[0012] Furthermore, in the context of a simple, quick and convenient filling of a cooling channel or a cooling circuit of an oil-cooled electric drive machine, it can be advantageous if an initial amount of oil is filled and oil is continuously added to the electric drive machine within a defined oil temperature range via a first and / or second oil filling means, wherein the first and the second oil filling means preferably differ in terms of their diameter.

[0013] A design with two oil filling devices of different diameters guarantees, in particular, a choice regarding the amount of oil to be filled. To minimize filling times, it can also be provided to fill simultaneously via two oil filling devices. The oil filling devices can be designed, for example, in the form of valves or filling nozzles or the like.

[0014] In the context of a supply of oil to an oil-cooled electric drive machine that can be regulated and finely dosed as precisely as possible, it can also be advantageous if an initial amount of oil is filled and / or oil is continuously added to the electric drive machine within the defined oil temperature range via the additional use of regulating elements, wherein the use of the regulating elements preferably regulates a flow rate of the oil.

[0015] It is also understood that individual, several, or all mandatory and / or optional steps of the method according to the invention can be performed in the proposed order, but also deviating from the proposed order. Individual, several, or all mandatory and / or optional steps of the method according to the invention can be performed repeatedly, for example, cyclically.

[0016] It is further understood that individual, several or all of the mandatory and optional steps of the method according to the invention can also be implemented by a computer.

[0017] The invention furthermore relates to an oil-cooled electric drive machine for carrying out a method described above. The oil-cooled electric drive machine according to the invention comprises an electric drive unit for driving the drive train, a cooling circuit with cooling channels arranged within the electric drive unit for dissipating heat, an oil draining means for draining residual oil from the electric drive machine, and at least one oil filling means for filling an initial amount of oil and for continuously adding oil to the electric drive machine within a defined oil temperature range. The oil can be temperature-controlled to achieve the defined oil temperature range (e.g.via the operation of a conveying means, such as an oil pump or by means of an oil-water heat exchanger) and an oil overflow for detecting an overflow of excess oil from the electric drive motor. Thus, the oil-cooled electric drive motor according to the invention has the same advantages as those already described in detail with regard to the method according to the invention.

[0018] With a view to ensuring a structurally simple oil storage capacity and the complete removal of residual oil from an electric drive unit, it can advantageously be provided that an oil reservoir is provided for filling the oil and draining residual oil. The oil reservoir is preferably arranged directly on the electric drive unit, with the cooling channels arranged within the electric drive unit being in fluid communication with the oil reservoir. A direct connection between the oil reservoir and the cooling channels enables, in particular, rapid and targeted filling and emptying of the cooling channels.

[0019] In the context of a supply of oil to an oil-cooled electric drive machine that can be regulated and finely dosed as precisely as possible, it can also be advantageous if the oil overflow for detecting an overflow of excess oil and / or the at least one oil filling means is arranged on the oil reservoir, wherein the oil overflow and / or the at least one oil filling means preferably has regulating elements for regulating a flow of oil, wherein the regulating elements are designed in particular in the form of spring-loaded elements.

[0020] To protect against oil leakage during normal operation, the oil overflow can further be provided with closure elements for detecting an overflow of excess oil and / or the oil filling means for closing during regular operation, wherein the closure elements are preferably designed in the form of screw-in plugs. A design of the closure elements in the form of screw-in plugs promises, in particular, a simple and cost-effective implementation, for example, one that can be carried out manually. It is understood that closure elements of other designs, such as automatically actuated valves, can also be provided.

[0021] Furthermore, within the scope of simple, fast, and convenient filling of a cooling channel or cooling circuit of an oil-cooled electric drive machine, it can be advantageous if, in addition to a first oil filling means for filling an initial oil quantity and for continuously adding oil to the electric drive machine within a defined oil temperature range, at least one second oil filling means is provided. The oil filling means are preferably arranged at different positions on the oil-cooled electric drive machine, with the diameter of the oil filling means, in particular, differing. By using a different diameter, the selection of an oil filling means can be adapted, for example, to the quantity and accuracy of the oil to be filled.

[0022] To achieve an effective cooling effect for the electric machine, it may also be advantageous to provide a conveying means for conveying the oil. The conveying means is preferably designed in the form of an oil pump, which is arranged in particular between the oil reservoir and the electric drive unit. By arranging an oil pump between the oil reservoir and the electric drive unit, effective conveying can be ensured.

[0023] Furthermore, with regard to particularly precisely controllable filling of a cooling circuit of an oil-cooled electric drive unit, it can be advantageous if a sensor unit is provided to detect an overflow of excess oil from the electric drive unit, wherein the sensor unit is preferably arranged at the oil overflow. Such a design promises not only particularly precisely controllable, but also easily automated filling of a cooling circuit of an oil-cooled electric drive unit.

[0024] The invention furthermore relates to a motor vehicle having an oil-cooled electric drive motor as described above. Thus, the motor vehicle according to the invention has the same advantages as those already described in detail with regard to the method according to the invention and the oil-cooled electric drive motor according to the invention.

[0025] Further advantages, features, and details of the invention will become apparent from the following description, which describes exemplary embodiments of the invention in detail with reference to the drawings. The features mentioned in the claims and in the description may be essential to the invention individually or in any combination.

[0026] They show schematically: Fig. 1 the individual steps of a method according to the invention for adjusting an oil level in an oil-cooled electric drive machine, Fig. 2 an oil-cooled electric drive machine according to the invention for driving a drive train according to a first embodiment.

[0027] Fig. 1 shows the individual steps of a method according to the invention for adjusting an oil level in an oil-cooled electric drive machine 2.

[0028] As per Fig. 1, the method according to the invention comprises the steps of draining 100 residual oil from the electric drive machine 2 via an oil draining means 4, filling 200 an initial amount of oil via an oil filling means 6, tempering 300 the oil (e.g. by operating a conveying means, such as an oil pump or by means of an oil-water heat exchanger) to achieve a defined oil temperature range T and continuously adding 400 oil to the electric drive machine 2 within the defined oil temperature range T via an oil filling means 6, until an overflow of excess oil from an oil overflow 8 is detected.

[0029] The draining 100 of residual oil from the electric drive machine 2 from an oil reservoir 16 can be carried out, for example, by an oil draining means 4 arranged in the bottom of an oil reservoir 16, such as a drain valve or the like.

[0030] Filling 200 of an initial oil quantity and continuously adding 400 oil to the electric drive machine 2 within a defined oil temperature range T can further be carried out via a first and / or second oil filling means 6a, 6b, which differ, for example, in terms of their diameter, wherein additionally regulating elements 18 can preferably be used to regulate a flow rate of the oil.

[0031] Fig. 2 shows an oil-cooled electric drive machine 2 according to the invention for driving a drive train according to a first embodiment.

[0032] As per Fig. 2, the oil-cooled electric drive machine 2 according to the invention for driving a drive train comprises an electric drive unit 10 for driving the drive train, a cooling circuit 12 with cooling channels 14 arranged within the electric drive unit for dissipating heat, an oil draining means 4 for draining 100 residual oil from the electric drive machine 2, at least one oil filling means 6 for filling 200 an initial amount of oil and for continuously adding 400 oil to the electric drive machine 2 within a defined oil temperature range T, wherein the oil can be temperature-controlled to reach the defined oil temperature range and has an oil overflow 8 for detecting an overflow of excess oil from the electric drive machine 2.

[0033] As per Fig. 2, the oil-cooled electric drive machine 2 according to the invention comprises an oil reservoir 16 for filling with oil and for draining 100 residual oil, wherein the oil reservoir 16 is arranged directly on the electric drive unit 10.

[0034] Furthermore, according to Fig. 2 the oil overflow 8 for detecting an overflow of excess oil as well as a first oil filling means 6a can be seen, which is arranged on the oil reservoir 16.

[0035] In addition to the first oil filling means 6a for filling 200 an initial amount of oil and for continuously adding 400 oil to the electric drive machine 2, the oil-cooled electric drive machine 2 according to the invention also has a second oil filling means 6b arranged remotely from the first oil filling means 6a.

[0036] Finally, according to Fig.2 also shows the conveying means 20, designed as an oil pump, for conveying the oil, as well as the sensor unit 22 for detecting an overflow of excess oil from the oil-cooled electric drive motor 2. The conveying means 20 is connected to the cooling circuit 12 via cooling lines 24. In addition to a sensor unit 22, a temperature sensor 26 is also provided for determining the oil temperature.

[0037] The above explanation of the embodiments describes the present invention exclusively by way of examples. Of course, individual features of the embodiments can be freely combined with one another, provided they are technically feasible, without departing from the scope of the present invention.

Claims

[1] Method for adjusting an oil level in an oil-cooled electric drive machine (2), comprising the steps: - draining (100) residual oil from the electric drive motor (2) via an oil draining means (4), - filling (200) an initial amount of oil via an oil filling agent (6), - Tempering (300) the oil to achieve a defined oil temperature range (T), - Continuously adding (400) oil to the electric drive machine (2) within the defined oil temperature range (T) via an oil filling means (6), until detection of an overflow of excess oil from an oil overflow (8). [2] Method according to claim 1, characterized by that the draining (100) of residual oil from the electric drive machine (2) takes place from an oil reservoir (16), wherein the residual oil is drained through an oil draining means (4) arranged in the bottom of the oil reservoir (16). [3] Method according to claim 1 or 2, characterized by that filling (200) of an initial amount of oil and continuously adding (400) oil to the electric drive machine (2) within a defined oil temperature range (T) takes place via a first and / or second oil filling means (6a, 6b), wherein the first and the second oil filling means (6a, 6b) differ in terms of their diameter. [4] Method according to one of the preceding claims, characterized by that filling (200) of an initial oil quantity and / or continuously adding (400) oil to the electric drive machine (2) within the defined oil temperature range (T) takes place via the additional use of regulating elements (18), wherein a flow rate of the oil is regulated via the use of the regulating elements (18). [5] Oil-cooled electric drive machine (2) for carrying out a method according to one of the preceding claims, comprising: - an electric drive unit (10) for driving the drive train, - a cooling circuit (12) with cooling channels (14) arranged within the electric drive unit (10) for dissipating heat, - an oil draining means (4) for draining (100) residual oil from the electric drive motor (2), - at least one oil filling means (6) for filling (200) an initial amount of oil and for continuously adding (400) oil to the electric drive machine (2) within a defined oil temperature range (T), wherein the oil can be tempered to reach the defined oil temperature range (T), - an oil overflow (8) for detecting an overflow of excess oil from the electric drive motor (2). [6] Oil-cooled electric drive machine (2) according to claim 5, characterized by that an oil reservoir (16) is provided for filling oil and for draining (100) residual oil, wherein the oil reservoir (16) is arranged directly on the electric drive unit (10), wherein the cooling channels (14) arranged within the electric drive unit (10) are in fluid communication with the oil reservoir (16). [7] Oil-cooled electric drive machine (2) according to claim 5 or 6, characterized by in that the oil overflow (8) for detecting an overflow of excess oil and / or the at least one oil filling means (6) is arranged on the oil reservoir (16), wherein the oil overflow (8) and / or the at least one oil filling means (6) has regulating elements (18) for regulating a flow of oil, wherein the regulating elements (18) are designed in the form of spring-loaded elements. [8] Oil-cooled electric drive machine (2) according to one of claims 5 to 7, characterized by that the oil overflow (8) for detecting an overflow of excess oil and / or the oil filling means (6) have closure elements for closing during regular operation, wherein the closure elements are designed in the form of screw-in plugs. [9] Oil-cooled electric drive machine (2) according to one of claims 5 to 8, characterized by in that, in addition to a first oil filling means (6a) for filling (200) an initial amount of oil and for continuously adding (400) oil to the electric drive machine (2) within a defined oil temperature range (T), at least one second oil filling means (6b) is provided, wherein the oil filling means (6a, 6b) are arranged at different positions of the oil-cooled electric drive machine (2), wherein the diameter of the oil filling means (6a, 6b) differs. [10] Oil-cooled electric drive machine (2) according to one of claims 5 to 9, characterized by that a conveying means (20) is provided for conveying the oil, wherein the conveying means (20) is designed in the form of an oil pump, wherein the conveying means (20) is arranged between the oil reservoir (16) and the electric drive unit (10). [11] Oil-cooled electric drive machine (2) according to one of claims 5 to 10, characterized by that a sensor unit (22) is provided for detecting an overflow of excess oil from the electric drive machine (2), wherein the sensor unit (22) is arranged on the oil overflow (8). [12] Motor vehicle (100) comprising an oil-cooled electric drive machine according to one of claims 5 to 11.

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