Electrical coupling device for wireless signal transmission in a region of a hollow machine component

Abstract

The invention relates to an electrical coupling device for wireless signal transmission in the region of a cavity (2) of at least partially hollow machine parts, comprising a hollow cylindrical coupling element (3) at the transmitter end, which fits into the cavity (2), is connected to a sensor (5) located in or on the machine part, and communicates via a transmission path inside the cavity with a pin-shaped coupling element (4) at the receiver end, which at least partially protrudes into the hollow cylindrical portion of the coupling element (3) at the transmitter end located in the cavity (2).

Description

Technical Field

[0001] The present invention relates to an electrical coupling device for transmitting wireless signals in the area of ​​a machine component, preferably a transmission device or an electric motor.

[0002] The application of this invention is primarily extended to automotive engineering. Particularly in hybrid or electric vehicles, drivetrain components such as electric motors, transmissions, and driveshafts are typically subject to sensor-based condition monitoring. For this purpose, condition monitoring sensors are used in areas such as gears, bearings, couplings, etc., which primarily measure component temperature but also measure vibration, voltage, torque, acceleration, angle, velocity, magnetic field strength, etc., so that they can be used, typically externally, by electronic evaluation units and / or transmitter and / or receiver units such as readers, for example, as part of a so-called condition monitoring system or as control parameters for control processing.

[0003] Signal transmission between the sensor and the electronic evaluation unit can be performed using wires in an interference-resistant manner, provided that the signal transmission does not occur between components that move relative to each other, especially rotating components. While electrically contact rotary feedthrough units do exist, they are highly susceptible to failure and require maintenance due to the principle of mechanical sliding contact. On the other hand, this invention focuses on the subject of wireless signal transmission, which can be achieved, for example, via radio waves, infrared radiation, etc. Furthermore, the solution according to the invention can also be used in other drive systems, such as wind turbines. Background Technology

[0004] DE 10 2014 200 639 A1 describes a system for determining condition data of a transmission, particularly a planetary gearbox, comprising at least one passive RFID sensor unit having a sensor and an RFID reader. It is only generally stated herein that the RFID reader is arranged on a first transmission component, and the RFID sensor unit is arranged on a second transmission component, the second transmission component being movable relative to the first transmission component. Such wireless signal transmission requires an interference-free radio link that is not damaged by adjacent components or external influences.

[0005] WO 2021 1004568A1 discloses an electrically driven machine, transmission, internal combustion engine, and combinations thereof equipped with several condition monitoring sensors for forming a sensor network. The sensors in the sensor network are preferably arranged at different locations within the machine and each is designed to measure physical variables. For this purpose, each sensor is wirelessly electrically connected to an electronic evaluation unit, which processes the signals wirelessly received from the sensors. When planning the sensor arrangement, it is also essential to ensure uninterrupted radio links.

[0006] However, in practice, it is not always possible to integrate condition monitoring sensors into machines in a manner that ensures uninterrupted wireless signal transmission, especially between machine parts that rotate relative to each other and in deep, hard-to-access machine structures.

[0007] Therefore, the object of the present invention is to create an electrically coupled device for wireless signal transmission in machine component areas, which uses simple technical means to ensure reliable forwarding of sensor signals to an external electronic evaluation unit. Summary of the Invention

[0008] This objective is achieved by the electrical coupling device according to claim 1. Claim 10 designates a transmission device or electric motor having the electrical coupling device according to the invention as a preferred application. The dependent claims point to advantageous further developments of the invention.

[0009] This invention incorporates the following technical teachings: an electrical coupling device for wireless signal transmission in a region of a cavity of at least partially hollow machine part includes a hollow cylindrical coupling element at a transmitter end, which is fitted into the cavity, connected to a sensor disposed in or on the machine part, and communicates via a transmission path, particularly an air path or oil as a dielectric, to a pin-type coupling element at a receiver end, which at least partially protrudes into the hollow cylindrical portion of the coupling element at the transmitter end disposed in the cavity. In this context, the solution according to the invention also includes interchangeability between the transmitter end and the receiver end. Preferably, the sensor transmits a signal, which is transmitted via the coupling element to a transmitter / receiver unit / evaluation unit.

[0010] In other words, the solution according to the invention therefore relates to an electrical coupling device for wireless signal transmission in which signals are transmitted within a machine component that is at least partially hollow. In this respect, sensor signals from a plurality of sensors arranged on the machine component can be acquired via a coupling element protruding into the cavity. The plurality of sensors can also be connected to a single coupling element. Therefore, the solution according to the invention is particularly suitable for acquiring sensor signals on rotating components.

[0011] In a particularly advantageous manner, the solution according to the invention can therefore be used, for example, for the wireless detection of the rotor temperature of a traction motor. If the temperature in the rotor becomes too high, the magnet will demagnetize and thus damage the electric motor. For this reason, more expensive magnetic materials are currently used to counteract this demagnetization tendency.

[0012] However, using the solution according to the invention, temperature can be measured directly at the magnet and the maximum permissible temperature can be precisely controlled. Another advantage regarding the determination of rotor temperature lies in the calculation of electric motor torque. Electric motor torque is typically determined via a characteristic graph where rotor temperature is a significant influencing variable. With the help of rotor temperature, which can be measured using a wireless temperature sensor, torque can be calculated more accurately. The temperature of temperature-critical transmission components, particularly bearings, can also be monitored and cooled as needed. This reduces oil requirements and thus reduces splash losses typically associated with pressurized oil lubrication.

[0013] The solution according to the invention allows for the effortless integration of numerous temperature sensors at any point in an electric motor or drive, for example, by implementing a sensor network, with the measurements detected and processed in an application-specific manner via a central electronic evaluation unit. This enables optimal system control.

[0014] According to a preferred embodiment of the invention, the hollow cylindrical coupling element at the transmitter end is designed in a tubular or sleeve shape. This element can be prefabricated and inserted into a similarly cylindrical cavity of a machine component having inner wall contacts, and attached to the cavity, for example, by adhesive bonding. It should be noted that an insulating layer is required between the hollow cylindrical coupling element, preferably made of metal such as copper, and the inner wall of the machine component, which is typically also made of a conductive material, preferably steel, and this insulating layer can be made, for example, of a non-conductive plastic. For example, the insulating layer can be part of a prefabricated tubular or sleeve-shaped coupling element, or it can be designed as a separate sleeve-shaped element and thus form its outer surface. This allows the hollow cylindrical coupling element to be fixed in the cavity of the hollow machine component by means of adhesive bonding or similar methods. In addition to such material bonding connections, force-fit connections, such as by press-fit, are also conceivable.

[0015] According to another embodiment of the hollow cylindrical coupling element at the sensor end, the hollow cylindrical coupling element can also be designed as a film or coating. In the case of a film, the hollow cylindrical coupling element has an electrically insulating layer applied to the outside. The cavity of the machine part can be easily lined with such a multilayer film, wherein adhesive bonding is recommended. Alternatively, it is conceivable to first coat the cylindrical cavity of the machine part with an electrically insulating layer, such as plastic, and then apply a conductive layer, such as that made of metal, to it. This can be achieved, for example, by vapor deposition in a vacuum.

[0016] Alternatively, it is conceivable that hollow cylindrical coupling elements be formed from circuit board materials, particularly flexible circuit boards or circuit boards composed of several parts, would be suitable for this purpose.

[0017] According to another aspect of the improved invention, a hollow cylindrical coupling element at the transmitter end and a pin-type coupling element at the receiver end are arranged coaxially. This enables particularly high signal quality, and the pin-type coupling element at the receiver end is arranged within the cavity structure of the machine component in a particularly well-protected manner. This is suitable for both mechanical considerations and radio communication with respect to interference signals.

[0018] To this end, a hollow cylindrical coupling element at the transmitter end is also proposed to protrude forward beyond the distal end of the pin-type coupling element at the receiver end. Preferably, in the vehicle application of particular interest here, the pin-type coupling element should be 5 mm to 10 mm shorter than the hollow cylindrical coupling element.

[0019] To further improve signal transmission, it is proposed that the length of the hollow cylindrical coupling element at the transmitter end and / or the pin-type coupling element at the receiver end be a multiple of the wavelength of the operating frequency of the wireless signal transmission. This value can be selected, for example, based on one-quarter, half, or three-quarters of the wavelength.

[0020] The pin-type coupling element at the receiver end can be designed as, for example, a rod, tube, sleeve, or screw and can be provided with a non-conductive coating to avoid direct electrical contact with the hollow cylindrical coupling element at the transmitter end, for example, due to unintentional deformation.

[0021] In the case of a coupling element in the form of a tube or sleeve, the coupling element can be arranged on a component connected to the housing. If the component connected to the housing is made of a metallic material, the inner surface of the tube-shaped or sleeve-shaped coupling element should be provided with an insulating layer. For example, the insulating layer can be part of a prefabricated tube-shaped or sleeve-shaped coupling element, or it can be designed as a separate sleeve-shaped element and thus form its inner surface.

[0022] According to another aspect of the improved invention, a non-magnetic and / or non-electric bearing element is proposed that can be provided around the pin-shaped coupling element at the receiver end and support the pin-shaped coupling element relative to the hollow cylindrical coupling element to protect the pin-shaped coupling element from unintentional deformation. A simple plastic disc is sufficient for this purpose, which is glued to the outer edge of the hollow cylindrical coupling element, and the pin-shaped coupling element protrudes through the central opening of the plastic disc.

[0023] As part of the solution according to the invention, wireless signal transmission can be based on SAW or RFID technology. Preferably, the operating frequency is the ISM band of 13.5MHz, 433MHz, 868MHz, 2.4GHz, or 5GHz, or other standard radio bands such as the SDR band.

[0024] Depending on the preferred form of the application, the at least partially hollow machine component is a gear pair or a hollow shaft of a drive shaft in the transmission system of a wind turbine or motor vehicle. In this respect, the solution according to the invention utilizes the cavity structure of this machine component, primarily for oil feed, to create a mechanically protected and reliable sensor connection for signal transmission.

[0025] Preferably, the machine components are rotatably mounted, and the coupling element at the reader end is attached to a fixed housing. An energy harvesting module or the like can be provided to supply power to the active sensor.

[0026] If the coupling element at the reader end is very thin and long, it can be reinforced or additionally supported. It can be arranged inside or outside the housing.

[0027] Electrodecoupling layers or sleeves on the coupling elements at the receiver or transmitter end are also advantageous. The dielectric constant of the dielectric, air, or oil between the coupling elements is particularly related to the length of the coupling element. The insulating layer between the coupling element at the transmitter end and the machine part, or between the coupling element at the receiver end and the part fixed to the housing, can also be dielectric. The dielectric constant of this insulating layer, or particularly, can also be related to the length of the coupling element. Attached Figure Description

[0028] Further improvements to the present invention will now be described using the accompanying drawings and a description of preferred exemplary embodiments. In the drawings:

[0029] Figure 1 A schematic longitudinal section is shown of a gear pair arranged on a hollow shaft and having a sensor for temperature detection connected via an electrical coupling device according to a first exemplary embodiment of the invention.

[0030] Figure 2 A schematic longitudinal section is shown of a gear pair arranged on a hollow shaft and having a sensor for temperature detection connected via an electrical coupling device according to a second exemplary embodiment of the invention.

[0031] Figure 3 A schematic longitudinal section is shown of a gear pair arranged on a hollow shaft, having a sensor for temperature detection connected via an electrical coupling device according to a third exemplary embodiment of the invention; and

[0032] Figure 4 A schematic longitudinal section is shown of a gear pair arranged on a hollow shaft and having a sensor for temperature detection connected via an electrical coupling device according to a fourth exemplary embodiment of the invention. Detailed Implementation

[0033] according to Figure 1 The hollow shaft 1 that carries the gear pair forms a cavity 2, in which a hollow cylindrical coupling element 3 is housed, and the hollow cylindrical coupling element interacts with a pin-shaped coupling element 4 via air as a dielectric to form a wireless signal transmission path.

[0034] A sensor 5 for detecting component temperature is arranged in the gear region outside the hollow shaft 1. This sensor is electrically connected to the hollow cylindrical coupling element 3 at the transmitter end via a plastic layer 6 serving as a dielectric. A large portion of the pin-type coupling element 4 at the receiver end, which communicates with it, protrudes into the hollow cylindrical portion of the coupling element 3 at the transmitter end, which is arranged in the cavity 2. In this respect, the hollow cylindrical coupling element 3 at the transmitter end protrudes forward beyond the distal end length 'a' of the pin-type coupling element 4 at the receiver end. The pin-type coupling element 4 is arranged coaxially with the hollow cylindrical coupling element 3.

[0035] In this exemplary embodiment, the pin-type coupling element 4 is designed as a rod made of conductive material.

[0036] according to Figure 2 The hollow cylindrical coupling element 3' at the transmitter end is designed as a membrane with an electrically insulating plastic coating on its outer surface. Additionally, the sensor 5 is housed in an insulating sensor cover 7, through which it is pressed into a corresponding hole in the machine component. In other respects, this exemplary embodiment corresponds to the exemplary embodiment described above.

[0037] exist Figure 3 In contrast to the exemplary embodiment described at the beginning, the pin-coupled element 4' at the receiver end is designed in the form of a tube, such that the pin-coupled element 4' has hollow waveguide characteristics to improve signal transmission. In other respects, this exemplary embodiment also corresponds to the exemplary embodiment described at the beginning.

[0038] according to Figure 4 A bearing element 8 is arranged in the intermediate region between the pin-type coupling element 4 and the hollow cylindrical coupling element 3 coaxially surrounding the pin-type coupling element. The bearing element 8 is made of non-magnetic and non-electric plastic and is used to support the rather thin pin-type coupling element 4 in this exemplary embodiment to ensure its desired position, even when the hollow shaft 1 rotates rapidly. In other respects, this exemplary embodiment also corresponds to the exemplary embodiment described at the beginning.

[0039] The present invention is not limited to the preferred exemplary embodiments described in more detail above. Rather, deviations from the preferred exemplary embodiments described above are conceivable and are included within the scope of the following claims. For example, the cavity of another machine part that is at least partially hollow may be used instead of the hollow shaft to accommodate the electrical coupling device according to the invention.

[0040] List of reference numerals

[0041] 1. Hollow Shaft

[0042] 2 cavities

[0043] 3 Hollow cylindrical coupling element

[0044] 4. Pin-type coupling element

[0045] 5 sensors

[0046] 6. Dielectric

[0047] 7. Sensor protective cover

[0048] 8. Bearing components

[0049] a. Indentation length.

Claims

1. An electrical coupling device for transmitting wireless signals in a region of a cavity (2) of at least partially hollow machine part, the electrical coupling device comprising a hollow cylindrical coupling element (3) at a transmitter end, the hollow cylindrical coupling element being fitted into the cavity (2), connected to at least one sensor (5) disposed in or on the machine part, and communicating with a pin-type coupling element (4) at a receiver end via a transmission path inside the cavity, the pin-type coupling element at least partially protruding into the hollow cylindrical portion of the hollow cylindrical coupling element (3) disposed in the cavity (2) at the transmitter end.

2. The electrical coupling device according to claim 1, Its features are, The hollow cylindrical coupling element (3) at the transmitter end is designed as a tube or sleeve.

3. The electrical coupling device according to claim 1, Its features are, The hollow cylindrical coupling element (3) at the transmitter end is designed as a membrane or coating.

4. The electrical coupling device according to claim 1, Its features are, The hollow cylindrical coupling element (3) at the transmitter end and the pin-shaped coupling element (4) at the receiver end are arranged coaxially.

5. The electrical coupling device according to claim 1, Its features are, The hollow cylindrical coupling element (3) at the transmitter end protrudes forward beyond the far end of the pin-type coupling element (4) at the receiver end.

6. The electrical coupling device according to claim 1, Its features are, The length of the hollow cylindrical coupling element (3) at the transmitter end and / or the pin-type coupling element (4) at the receiver end is a multiple of the wavelength of the signal transmission operating frequency.

7. The electrical coupling device according to claim 1, Its features are, The pin-type coupling element (4) at the receiver end is designed as a rod, tube, sleeve or screw.

8. The electrical coupling device according to claim 1, Its features are, The pin-type coupling element (4) at the receiver end is supported or electrically decoupled from the machine component by at least one non-magnetic and / or non-electric bearing element (8).

9. The electrical coupling device according to claim 1, Its features are, The machine component having the cavity (2) is designed as a hollow shaft (1) in the transmission system of a wind turbine or motor vehicle.

10. A transmission and / or electric motor for a hybrid vehicle or electric vehicle, having an electrical coupling device for wireless signal transmission in the region of a cavity (2) of at least partially hollow machine parts according to any one of claims 1-9.

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