Powertrain component for a motor vehicle, method for monitoring a powertrain component and motor vehicle

Abstract

The invention relates to a drivetrain component (10) for a motor vehicle (K), comprising a housing element (40), a shaft (22) rotatably mounted on the housing element and designed for torque transmission, and at least one shaft seal (50) for sealing a space (12) between the housing element (40) and the shaft (22) against the escape of lubricant (14) contained in an interior space (42) of the housing element (40). According to the invention, the drivetrain component (10) includes a monitoring device (70) designed to monitor the condition of a lubricating film formed by the lubricant (14) between the shaft seal (50), which is at least partially electrically conductive, and the electrically conductive shaft (22).Further aspects of the invention relate to a method for monitoring a powertrain component (10) of a motor vehicle (K), a motor vehicle (K) and a shaft sealing element (50) for a powertrain component.

Description

[0001] The invention relates to a drivetrain component for a motor vehicle, comprising a housing element, a shaft rotatably mounted on the housing element, which shaft is designed to transmit torque, and at least one shaft sealing element for sealing a gap between the housing element and the shaft against the escape of lubricant contained in a housing interior of the housing element. Further aspects of the invention relate to a method for monitoring a drivetrain component and a motor vehicle.

[0002] DE 10 2018 131 181 B3 discloses a bearing assembly comprising a shaft and a housing. A bearing is arranged between the shaft and the housing. A seal is assigned to the bearing, which seals the housing gap between the shaft and the housing from the environment. The seal has a support ring made of electrically insulating material and a sealing disc attached to the support ring. The sealing disc is electrically conductive and lies sealingly against the shaft. An evaluation unit is provided, which is electrically conductively connected to the housing and the sealing disc. The evaluation unit is equipped to reduce an electrical voltage that arises between the housing and the sealing disc during dynamic operation and to record the electrical resistance between the housing and the sealing disc.

[0003] With this bearing arrangement, a simple design can be monitored and protected against the occurrence of high electrical voltages. However, there are other sources of interference from which drivetrain components should be protected to prevent failure.

[0004] The object of the present invention is to provide a drive train component for a motor vehicle, a method for monitoring a drive train component and a motor vehicle, by means of which effective condition monitoring is possible to protect against damaging events.

[0005] This object is achieved by a drive train component having the features of patent claim 1, by a method having the features of patent claim 6, and by a motor vehicle having the features of patent claim 9. Advantageous embodiments with expedient further developments of the invention are specified in the subclaims.

[0006] A first aspect of the invention relates to a drive train component for a motor vehicle, comprising a housing element, a shaft which is rotatably mounted on the housing element and is designed to transmit torque, and at least one shaft sealing element for sealing an intermediate space between the housing element and the shaft against the escape of lubricant carried in an interior space of the housing element. The shaft can be designed, for example, as a rotor shaft, in particular of a rotor. The drive train component can generally be designed as an electrical machine, or E-machine for short, which can also be referred to as a traction machine, and is designed and configured in particular for driving the motor vehicle. The shaft sealing element can be designed as a dust seal and additionally or alternatively as a radial shaft sealing element.The shaft sealing element can therefore be formed on the seal that rests on the shaft during operation of the drive train component, which can form a sealing contact with the shaft.

[0007] In order to prevent too little lubricant from reaching the shaft sealing element during operation of the drive train component, which entails the risk of the shaft sealing element running dry, the invention provides that the drive train component has a monitoring device designed to monitor the condition of a lubricating film formed by the lubricant between the shaft sealing element, which is designed to be electrically conductive at least in some regions, and the electrically conductive shaft. This is advantageous because the lubricating film can influence the electrical conductivity at a contact area where the shaft sealing element or at least one sealing lip of the shaft sealing element rests on the shaft, so that any interruption in the lubricating film can be detected particularly quickly. The shaft sealing element can preferably be formed, at least in some regions, from electrically conductive PTFE.The expression "the shaft sealing element is electrically conductive at least in some regions" is to be understood within the context of the present disclosure to mean that the shaft sealing element can have at least one electrically conductive shaft sealing element sub-region intended for contact with the shaft, for example the sealing lip of the shaft sealing element. The shaft sealing element can also preferably have a shaft sealing element insulation region, via which the (electrically conductive) shaft sealing element sub-region can be electrically insulated, for example, from the housing element. Alternatively, the shaft sealing element can also be completely electrically conductive, and an electrical insulator different from the shaft sealing element can be arranged between the housing element and the shaft sealing element.

[0008] By means of the monitoring device, an electrical voltage can preferably be applied to the shaft sealing element on the one hand and to the shaft on the other. In other words, a first voltage potential can be applied to the shaft sealing element and a second voltage potential, different from the first voltage potential, can be applied to the shaft, so that a potential difference is established between the shaft sealing element and the shaft. From this, a resistance across the shaft sealing element and the shaft can be deduced. It is also conceivable for the monitoring device to send a current with a predetermined current intensity through the shaft sealing element, the lubricating film and the shaft and then determine, in particular measure, an electrical voltage drop formed across an electrical resistance. The electrical resistance can be formed by the shaft sealing element, the lubricating film and the shaft.If the current and voltage are known, the resistance can be determined using Ohm's law. This is based on the knowledge that the resistance changes as the condition of the lubricating film changes. If the lubricating film breaks off, even just in one area, so that the shaft sealing element comes into direct contact with the shaft, which corresponds to a poor condition of the lubricating film, the resistance drops suddenly and can be measured across the shaft sealing element, the lubricating film, and the shaft. If, on the other hand, the lubricating film is intact and therefore the condition of the lubricating film is sufficiently good, the lubricating film between the shaft sealing element and the shaft acts as an electrical insulator, so that a correspondingly high value of the electrical resistance can be measured using the monitoring device.

[0009] In an advantageous development of the invention, the monitoring device comprises a measuring device by means of which an electrical variable characterizing the condition of the lubricating film can be determined. Electrical variables can generally be detected particularly quickly, thus enabling a particularly rapid response to the determined condition of the lubricating film.

[0010] In a further advantageous development of the invention, the monitoring device has an electrically conductive shaft contact element designed to make contact with the shaft. This is advantageous because this shaft contact element enables direct electrical contact to be made with the shaft. The shaft contact element can be a brush element, for example. It is particularly advantageous if the shaft contact element forms a point contact with the shaft, whereby particularly low friction losses occur during a relative movement between the shaft rotating during operation of the drive train component and the shaft contact element. Particularly low friction losses also occur if the shaft contact element is in contact with the shaft at a shaft center axis, in particular by forming a point contact with the shaft.

[0011] In a further advantageous development of the invention, the monitoring device has an electrically conductive shaft sealing element contact element designed for contacting the shaft sealing element. This is advantageous because it allows electrical contact to be made directly at the shaft sealing element. In the simplest case, the shaft sealing element contact element can be designed as an electrical cable, but preferably as an electrical connector.

[0012] In a further advantageous development of the invention, the monitoring device is configured to control a lubricant pump of the drivetrain component, which is designed to supply individual components of the drivetrain component with lubricant, depending on the condition of the lubricating film. This is advantageous because it ensures a particularly demand-oriented lubricant supply by means of the lubricant pump. These individual components can include not only the shaft but also gears and bearings, for example, rolling bearings.

[0013] A second aspect of the invention relates to a method for monitoring a drivetrain component of a motor vehicle, which comprises a housing element, a shaft rotatably mounted on the housing element, which is designed to transmit torque, and at least one shaft sealing element, which is used to seal an intermediate space between the housing element and the shaft against the escape of lubricant carried in an interior space of the housing element. According to the invention, it is provided that the drivetrain component comprises a monitoring device by which a state of a lubricating film formed by the lubricant between the electrically conductive shaft sealing element and the electrically conductive shaft is monitored. This can effectively prevent too little lubricant from reaching the shaft sealing element during operation of the drivetrain component.

[0014] In an advantageous development of the invention, a lubricant pump designed to supply individual components of the drive train component with lubricant is controlled by the monitoring device depending on the condition of the lubricating film. This is advantageous because it ensures a particularly demand-oriented lubricant supply by means of the lubricant pump.

[0015] A third aspect of the invention relates to a motor vehicle with a drivetrain component according to the first aspect of the invention. In such a motor vehicle, effective condition monitoring can be implemented to protect against damaging events.

[0016] A fourth aspect of the invention relates to a shaft sealing element for a drive train component according to the first aspect of the invention. According to the invention, the shaft sealing element has at least one electrical connection.

[0017] The preferred embodiments and their advantages presented with respect to one of the aspects apply accordingly to the other aspects of the invention and vice versa.

[0018] The features and combinations of features mentioned above in the description as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the respective combination specified, but also in other combinations or on their own, without departing from the scope of the invention.

[0019] Further advantages, features and details of the invention emerge from the claims, the following description of preferred embodiments and from the drawings.

[0020] The invention is explained once again below using a specific embodiment. This shows: Fig. 1 a schematic sectional view of a drive train component which is assigned to an abstractly represented motor vehicle.

[0021] Fig. 1 shows a schematic representation of a motor vehicle K with a drive train component 10. The drive train component 10 is designed as a traction machine and serves to drive the motor vehicle K.

[0022] The drive train component 10 comprises a housing element 40, a stator 30 arranged in a housing interior 42 of the housing element 40, and a shaft 22 which is rotatably mounted on the housing element 40 and in the housing interior 42 by means of respective rolling bearings 26, 28 of the drive train component 10 and which is designed for torque transmission. The shaft 22 is designed as a rotor shaft and is connected to a rotor 20 of the drive train component 10. A shaft center axis 24, which can also be referred to as the rotational axis of the shaft 22, is shown in dashed lines in Fig. 1. The housing interior 42 can be divided into a brush chamber area 44, in which electrical brush elements (not shown here) for supplying the drive train component 10 with electrical energy can be arranged. Furthermore, the housing interior 42 can be divided into a chamber area 46, also called an EMA chamber, for accommodating the stator 30, the rotor 20, and a large portion of the shaft 22, and a gear chamber area 48, which can serve to accommodate a gear (not shown here).

[0023] Furthermore, the drive train component 10 has a first shaft sealing element 50, which serves to seal an intermediate space 12 between the housing element 40 and the shaft 22 against the escape of lubricant 14 contained in the housing interior 42 of the housing element 40. The first shaft sealing element 50 can be designed, for example, as a dust seal or as an oil seal. A second shaft sealing element 60 is also provided, which, like the first shaft sealing element 50, is designed as a radial shaft seal and can be designed as a dust seal or as an oil seal.

[0024] The drive train component 10 has a monitoring device 70, which is designed to monitor the condition of a lubricating film formed by the lubricant 14 between the shaft sealing element 50, which is at least partially electrically conductive, and the electrically conductive shaft 22. The shaft sealing element 50 has at least one electrical connection 52, via which the shaft sealing element 50 is connected to the monitoring device 70.

[0025] The shaft sealing element 50 has an electrically conductive shaft sealing element sub-region (not designated in more detail) intended for contact with the shaft 22, which is designed as a sealing lip and is electrically conductively connected to the electrical connection 52. The sealing lip is made of PTFE in the present case and lies directly against the shaft 22, forming a sealing seat. Also not designated in more detail is a shaft sealing element insulation region of the shaft sealing element 50, via which the (electrically conductive) shaft sealing element sub-region is electrically insulated from the housing element 40. Alternatively, the shaft sealing element 50 can also be designed to be completely electrically conductive, and an electrical insulator different from the shaft sealing element 50, also not shown here, can be arranged between the housing element 40 and the shaft sealing element 50.In any case, the respective insulation measure can prevent a current flow from the electrically conductive PTFE sealing lip to the housing element 40.

[0026] The monitoring device 70 has a measuring device 72 by means of which an electrical quantity characterizing the state of the lubricating film can be determined.

[0027] Furthermore, the monitoring device 70 has an electrically conductive shaft contact element 80 designed for contacting the shaft 22, as well as an electrically conductive shaft sealing element contact element 90 designed for contacting the shaft sealing element 50. The shaft contact element 80 forms a point contact on the shaft center axis 24 with the shaft 22. For this purpose, the electrically conductive shaft contact element 80 can have a tip, by means of which the shaft contact element 80 makes point contact, i.e., point-like contact, with the shaft 22 at the shaft center axis 24. It is also advantageous to design the shaft contact element 80 as a slip ring, which enables particularly reliable electrical contacting. The shaft sealing element contact element 90 can be designed as an electrical connector plug, which Fig. 1 and can be electrically conductively coupled to the electrical connection 52 of the shaft sealing element 50 in a reversibly detachable manner. In other words, the electrical connection 52 and the shaft sealing element contact element 90 can form an electrical contact, in particular one that can be detached reversibly and thus non-destructively. The shaft sealing element contact element 90 is electrically conductively connected to the monitoring device 70 via a first line element 16, whereas the shaft contact element 80 is connected to the monitoring device 70 via a second line element 18.

[0028] The monitoring device 70 is generally designed to control a lubricant pump 100 of the drive train component 10, which is designed to supply individual components 20 of the drive train component 10 with lubricant 14, depending on the state of the lubricating film.

[0029] Under normal conditions, the lubricating film is sufficiently good to ensure a continuous lubricating film, particularly an oil film, between the shaft sealing element 50, designed as a radial shaft seal, and the shaft 22 (rotor shaft), thus providing hydrodynamic lubrication. The electrical resistance between the shaft sealing element 50 and the shaft 22 is very high because the lubricating film acts as an electrical insulator. A low electrical resistance value indicates a poor condition of the lubricating film.

[0030] In summary, the electrical resistance between the shaft sealing element 50 and the shaft 22 (rotor shaft) can be determined via the monitoring device 70, also referred to as the control unit, whereby the voltage difference can be measured using the measuring device 72. Of particular interest is the condition of the lubricating film when the shaft sealing element 50, as in Fig.1, is designed as the outermost seal of the drive train component 10, thus determining the electrical resistance of the last sealing lip (air side) of the shaft sealing element 50. Through the special interface between the shaft seal and the rotor shaft, lubricant 14, particularly in the form of oil, is always pumped from the air side (e.g., coming from the brush chamber 44) toward the oil side (lubricant side), i.e., toward the chamber area 46. However, this requires a sufficient lubricant supply (oiling) in all operating situations of the drive train component 10 by the oil pump 100. By applying an electrical voltage using the monitoring device 70, the overall electrical resistance between the shaft sealing element 50 (radial shaft seal) and the shaft 22 can be determined, and thus the condition of the lubricating film can be determined.

[0031] If the electrical resistance decreases due to insufficient lubrication of the lubricating film between the shaft sealing element 50 and the shaft 22, or if the lubricating film collapses completely, causing the resistance to decrease particularly significantly, the monitoring device 70 can control a control unit of the oil pump 100 so that the latter delivers more lubricant 14.

[0032] This allows a particularly quick response to and prevention of impending lubrication insufficiency. List of reference symbols 10 Drivetrain components 12 space 14 Lubricants 16 first line element 18 second line element 20 rotors 22 Wave 24 Shaft center axis 26 rolling bearings 28 rolling bearings 30 Stator 40 Housing element 42 Housing interior 44 Brush room area 46 Room area 48 Gearbox area 50 first shaft sealing element 52 electrical connection 60 second shaft sealing element 70 Monitoring device 72 measuring device 80 shaft contact element 90 Shaft seal contact element 100 oil pump K Motor vehicle QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2018 131 181 B3

[0002]

Claims

[1] Drive train component (10) for a motor vehicle (K), with a housing element (40), with a shaft (22) which is rotatably mounted on the housing element and is designed for torque transmission, and with at least one shaft sealing element (50) for sealing an intermediate space (12) between the housing element (40) and the shaft (22) against the escape of lubricant (14) guided in a housing interior space (42) of the housing element (40), characterized by in that the drive train component (10) has a monitoring device (70) which is designed to monitor a state of a lubricating film formed by the lubricant (14) between the shaft sealing element (50), which is designed to be electrically conductive at least in some regions, and the electrically conductive shaft (22). [2] Drive train component (10) according to claim 1, characterized bythat the monitoring device (70) has a measuring device (72) by means of which an electrical variable characterizing the state of the lubricating film can be determined. [3] Drive train component (10) according to claim 1 or 2, characterized by that the monitoring device (70) has an electrically conductive shaft contact element (80) designed to make contact with the shaft (22). [4] Drive train component (10) according to one of the preceding claims, characterized by that the monitoring device (70) has an electrically conductive shaft sealing element contact element (90) designed for contacting the shaft sealing element (50). [5] Drive train component (10) according to one of the preceding claims, characterized bythat the monitoring device (70) is designed to control a lubricant pump (100) of the drive train component (10), which is designed to supply individual components (20) of the drive train component (10) with lubricant (14), depending on the state of the lubricating film. [6] Method for monitoring a drive train component (10) of a motor vehicle (K), which comprises a housing element (40), a shaft (22) which is rotatably mounted on the housing element (40) and is designed to transmit torque, and at least one shaft sealing element (50) which is designed to seal an intermediate space (12) between the housing element (40) and the shaft (22) against the escape of lubricant (14) guided in a housing interior space (42) of the housing element (40), characterized byin that the drive train component (10) comprises a monitoring device (70) by which a state of a lubricating film formed by the lubricant (14) between the shaft sealing element (50), which is at least partially electrically conductive, and the electrically conductive shaft (22) is monitored. [7] Method according to claim 5, characterized by that a lubricant pump (100) designed to supply individual components (20) of the drive train component (10) with lubricant (14) is controlled by means of the monitoring device (70) as a function of the state of the lubricating film. [8] Motor vehicle (K) with a drive train component (10) according to one of claims 1 to 5. [9] Shaft sealing element (50) for a drive train component (10) according to one of claims 1 to 5, characterized by that the shaft sealing element (50) has at least one electrical connection (52).

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