WO2020126190A1

WO2020126190A1 - Electric motor comprising a thermochromic component

Info

Publication number: WO2020126190A1
Application number: PCT/EP2019/080329
Authority: WO
Inventors: Ralph Wystup
Original assignee: Ebm-Papst Mulfingen Gmbh & Co. Kg
Priority date: 2018-12-18
Filing date: 2019-11-06
Publication date: 2020-06-25
Also published as: DE102018132743A1; CN210093061U; EP3833948A1; CN112888923A

Abstract

The invention relates to an electric motor comprising a component, at least part of said component being formed from a thermochromic material or the surface (14, 15, 16) of at least part of said component being provided with a coating made of the thermochromic material. The electric motor has: a camera (21) which is designed to capture the surface (14, 15, 16) of the component using image technology; and an evaluation unit which is designed to determine a two-dimensional temperature field along the surface (14, 15, 16) from images captured by the camera (21).

Description

Electric motor with thermochromic component

Description:

The invention relates to an electric motor with a component for temperature detection and temperature monitoring and a method for temperature detection and temperature monitoring.

Temperature monitoring on electric motors is known in the prior art. For this purpose, sensors such as thermal switches or thermal sensors are mostly used, which measure the temperature in particular on the windings of the electric motor. Such sensors, however, can only detect a temperature selectively. In order to enable flat temperature monitoring, it is known to use temperature models to use the thermal temperature values to determine a temperature distribution to calculate. However, this sometimes requires high computing power, which means that the hardware required for the calculations is expensive and takes up a lot of space. In addition, the thermal models on the basis of which the temperature distribution is calculated can be faulty and are usually not adapted to changes in the conditions and some of them are not customizable. For example, a calculated temperature distribution can deviate from the actual temperature distribution due to wear or maintenance measures carried out. By using a large number of sensors, an exact temperature distribution can be calculated, but the problem that the model used for this usually does not correspond to reality remains.

Alternative methods for flat temperature detection or electric motors, in which the temperatures are detected by methods such as, for example, thermal imaging cameras, are usually expensive and therefore cannot be used economically for permanent temperature monitoring.

The invention is therefore based on the object of overcoming the abovementioned disadvantages and of providing an electric motor and a method with or with which flat temperature distributions on components can be recorded inexpensively and economically.

This object is achieved by the combination of features according to claim 1.

According to the invention, an electric motor with a component is proposed, the component being formed at least partially from a thermochromic material or with a coating on the surface thereof

thermochromic material is provided. In addition, the electric motor has one Camera and an evaluation unit. The camera is designed to capture the surface of the component using image technology and preferably in color. The evaluation unit is designed to determine a two-dimensional temperature field along the surface from images captured by the camera. In addition to using a color camera to record color images and determining the temperatures from the colors, a black and white camera can also be used, the temperatures not being assigned to the colors but to the grayscale.

Due to the thermochromic material, the component is designed to discolor as a function of a component temperature, so that the discoloration or the resulting color gradient on the surface can be detected by the camera.

Thermochromism is the property of certain substances to change color when the temperature changes. This process is reversible so that the substance or the component returns to its original color after cooling. The color changes are caused by changes in the molecular or crystal structure.

The component can therefore be produced, for example, from a mixture of a carrier material such as plastic and a thermochromic substance. As an alternative to a mixture which can be processed into the component, for example by an injection molding process, a surface of the component can also be coated with a thermochromic material such as paint or lacquer. Such temperature measurement colors (also called thermochromic colors or thermochromic colors) are coating materials which indicate temperature changes due to color change or color change.

Depending on the thermochromic substance used, a Temperature changes, for example from white green or from black turquoise.

In order to enable temperature detection also in an interior of the electric motor or in the dark, an advantageous further development provides that the electric motor further comprises an illuminating device which is designed to illuminate the surface which is captured by the camera. An LED is particularly advantageous for this purpose as lighting means, since it itself generates no or only a slight temperature and does not additionally heat the illuminated surface or the room it illuminates. A further embodiment, which is advantageous, provides that the component determines a cavity and the surface captured by the camera is an inner surface of the component that faces the cavity. A large area can thus be captured by the camera.

In particular, a variant of the invention is also advantageous in which the electric motor comprises a stator with a plurality of stator windings and an intermediate space is determined between two immediately adjacent stator windings of the plurality of stator windings, in which the component is arranged.

The stator preferably comprises a multiplicity of stator teeth arranged in a star shape, it being possible for a stator tooth to be T-shaped and for each stator winding to be arranged or wound on a stator tooth. The between the stator windings or between the

Distances lying between stator teeth correspond to the interspaces, wherein said component can be arranged in at least one of the interspaces. The component is preferably in direct contact with the directly adjacent stator windings or is only spaced apart by a narrow air gap, so that the heat of the stator winding (s) is transferred to the directly adjacent or directly adjacent component. The Transfer heat to an outer surface facing the stator winding, as a result of which the component heats up and the discoloration of the thermochromic material on the surface can be detected by the camera, the surface preferably being the inner surface of the outer surface on the component. Between two immediately adjacent stator teeth, a stator winding or the strands of a stator winding can be arranged, or alternatively two stator windings or the strands of two stator windings.

If a temperature or the temperature profile of a specific electric motor component or the stator windings is to be recorded, a variant of the invention is advantageous in which the component is designed as a covering which determines the cavity and which has an outer surface facing away from the cavity is adjacent to or directly adjacent to the adjacent stator windings. In this context, it is understood to be directly adjacent that the outer surface of the component or the component is only spaced from the stator winding by a preferably narrow air gap of at most 1 mm. Furthermore, it is provided that the cladding is formed from the thermochromic material or on an inner surface facing the cavity with the

thermochromic material is coated. The lighting means is also designed to illuminate the cavity and the inner surface of the lining facing the cavity. Furthermore, the camera is designed to image the cavity and the inner surface of the cladding facing the cavity. In addition, an embodiment of the electric motor is advantageous in which the electric motor has a rotor that can be rotated around the stator.

The cavity determined by the cladding is also opened in the radial direction towards the rotor and the camera is designed to record the rotor by image technology. Through the image or camera technology detection of the rotor the rotor position relative to the stator can be determined and used for the rotor position for controlling the electric motor.

For the precise detection of the rotor position in relation to the stator, an advantageous further development also provides that an angular scale encircling the stator in the circumferential direction is provided on an inner surface of the rotor which faces the stator and which can be detected by the camera. Points or sections of the rotor are assigned or can be assigned a relative rotational angle position with respect to the stator by means of the angle scale.

In order to be able to determine temperature distributions or temperature fields from the images captured by the camera, a further advantageous variant of the invention provides that the camera is designed to capture the surface of the component partly in terms of image technology and in color, and the evaluation unit is designed to be in the colors of Associate images of the surface with the camera and record temperature values from the temperature values associated with the surface and determine the two-dimensional temperature field along the surface of the component.

In a further embodiment, it is advantageous that the two-dimensional temperature field determined by the evaluation unit is a scalar field in which a temperature value is assigned to each point of the surface of the component detected by the camera.

In addition to the temperature distribution or the temperature field, further characteristic values can be recorded by the camera and determined by the evaluation unit. For this purpose, a further development of the invention provides that the evaluation unit is further configured to determine a degree of contamination of the surface and / or a state of the surface or the component from the images captured by the camera. In addition to the surface, the space captured by the camera, for example a cavity determined by the component, can also be used to monitor and record measured values be used. If, for example, smoke is detected by the camera in the cavity, this can be detected by the evaluation unit, so that overheating or a defect can be concluded and control measures can be initiated. Depending on the camera used, the color intensity or the exact color in the images captured by the camera may vary slightly. This can also occur with cameras of the same model. In order not to have to individually adjust the cameras or the evaluation unit, which can also evaluate images from several cameras, an advantageous variant provides that a temperature-resistant color scale is provided on the surface, which can be detected by the camera and certain colors at certain temperatures assigns, where a color is assigned to a temperature or a temperature limit. The evaluation unit is preferably designed to assign the colors of the color scale to specific temperatures from the recorded color scale and from this to determine the temperature distribution of the surface of the component recorded in the image. This eliminates the need for manual adjustment or calibration of the evaluation unit or the camera. The color scale can only specify two values, for example, so that, for example, a first color stands for temperatures up to 50 ° C and a second color for temperatures above 100 ° C. Alternatively, the color scale can also represent different color intensities, a multitude of colors or color gradients, so that temperature values can be assigned to the different colors or gradations. Because of the

Color scale covered area of the surface is only very small, the temperature actually prevailing in the area of the color scale can, for example, from the temperatures of the areas of the surface adjacent to the color scale. b. can be calculated by interpolation.

Since it should be possible to determine a flat temperature distribution on the component of the electric motor, an advantageous embodiment of the Electric motor that a position scale is provided on the surface, which can be detected by the camera and each points or sections on the surface assigns a specific position value. As a result, the evaluation unit can assign a specific position to a temperature value detected by the color. The position scale can also be designed as a grid or grid that preferably extends completely over the surface.

The component can also be designed as a closed or open in the longitudinal direction hollow cylinder, which determines the cavity in its interior and the camera with the lighting means. In such a case, the hollow cylinder can be completely arranged in a stator winding.

Another aspect of the invention relates to a method for detecting a two-dimensional temperature field along a surface of a component. The component is at least partially formed from a thermochromic material or on its surface with a coating of the

thermochromic material. Furthermore, the surface is formed by the thermochromic material to change color depending on a component temperature on the surface. In addition, a camera is provided for the method, which captures the surface of the component using image technology, the images captured by the camera being transmitted to an evaluation unit. The evaluation unit assigns colors from the images captured by the camera to the surface temperature values. The evaluation unit preferably assigns the temperature values to specific points on the surface. The evaluation unit determines the two-dimensional temperature field along the surface of the component from the temperature values assigned to the surface.

According to a further aspect of the invention, a method for Acquisition of a two-dimensional temperature field on a

Stator winding of an electric motor proposed. A component is arranged on the stator winding, the component being at least partially formed from a thermochromic material or provided on its surface with a coating of the thermochromic material. The surface is formed by the thermochromic material to discolor depending on a component temperature on the surface. A camera is also provided for the method, which captures the surface of the component and the images captured by the camera are transmitted to an evaluation unit. The evaluation unit assigns colors from the images of the surface and preferably certain points on the surface to temperature values and determines the two-dimensional temperature field along the surface of the component from the temperature values assigned to the surface. The two-dimensional temperature field of the stator winding or the surface of the stator winding facing the component is determined from the temperature values assigned to the surface.

An advantageous further development of the method also provides that the electric motor comprises a stator with a large number of stator windings and the component is arranged as a cladding in an intermediate space between two stator windings arranged directly next to one another and directly adjacent to or adjacent to the stator windings arranged next to one another is adjacent. The evaluation unit assigns colors from the images of the surface to temperature values and determines from the temperature values assigned to the surface the two-dimensional temperature field along the surface of the component and thus a two-dimensional temperature field of the respective stator winding for each of the two stator windings arranged directly next to one another.

Other advantageous developments of the invention are characterized in the subclaims or are described below together with the description. Description of the preferred embodiment of the invention with reference to the figures. Show it:

1 stator of an electric motor;

2 component for determining a temperature field on a stator; 3 stator of an electric motor with a rotor;

Fig. 4 stator of an electric motor;

5a - 5d discoloration of a component by thermochromism;

The figures are exemplary schematic. The same reference symbols in the figures indicate the same functional and / or structural features. FIG. 1 shows a section and a cross section of a stator 10 of an electric motor realized as an external rotor. The stator 10 has an annular stator back 1 T, from which stator teeth 11 extend radially outward in a star shape and uniformly distributed in the circumferential direction U. The stator teeth 11 are each T-shaped, so that on a section lying outside in the radial direction

Stator teeth 11 each connect a tooth section which extends in the circumferential direction U and essentially orthogonally to the section of the respective stator tooth 11 extending in the radial direction R. A gap is formed between each two adjacent stator teeth 11, in which the stator windings 12 are received.

In the embodiment of the invention illustrated in FIG. 1, the component is designed as a cladding 13, a cladding 13 in each case being arranged in an intermediate space between two immediately adjacent stator teeth 11. The cladding 13 lies directly on two

Stator windings 12 and on the stator back 1 T, the cladding 13 each defining a cavity 17 in which a camera 21 and a arranged as LED lighting means 22 is arranged. As shown in FIG. 2, the camera 21 and the lighting means 22 are preferably arranged at one end section in the longitudinal direction of the cavity 17, so that the component or the covering 13 is illuminated by the lighting means 22 over its entire length and by the camera 21 technically he can be captured. The fact that the panel 13 on two

Stator windings 12 and the stator back 11 ', the surface of the component is essentially divided into three sections. A first section of the cladding lies against a first stator winding 12 ′, so that a first section 14 of the surface is essentially heated by the first stator winding 12 ′ and can change color due to the temperature of the first stator winding 12 ′, so that the camera 21 the first section 14, the temperature field on the first stator winding 12 'can be determined. A second section of the cladding lies against the back of the stator 1 T, so that a second section 15 of the surface essentially deviates from that

Stator back 1 T is heated and by the temperature of the

Can discolor the stator back 1 T, so that the temperature field of the section of the stator back 1 T between the first stator winding 12 ′ and a second stator winding 12 ″ can be determined by the camera 21 on the second section 15. A third section of the panel lies on the second

Stator winding 12 ", so that a third section 16 of the surface is essentially heated by the second stator winding 12" and can change color due to the temperature of the second stator winding 12 ", so that the temperature field at the second section 16 is caused by the camera 21 - th stator winding 12 "can be determined.

FIG. 2 shows a cladding 17 of the stator 10 from FIG. 1, from a viewing direction identified by A in FIG. 1. A position scale 18 is arranged on the second section 15 of the surface, by means of which discolorations recorded by image technology can be assigned a position on the cladding 17. The position scale 18 can alternatively also be virtual from the evaluation unit in FIG the image captured by the camera 21 can be included. The position scale 18 can also be additionally provided on the first section 14 and the third section 16. In addition to the position scale 18, a color scale 19 is also provided, as a result of which the evaluation unit for colors which are assigned to a temperature has a comparison value directly in the image captured by the camera 21. In FIG. 2, the color scale 19 has only two values by way of example. For example, the "color" black can be assigned a first temperature limit of 100 ° C and the "color" white a second temperature limit of 60 ° C. The second temperature limit value or the lowest temperature limit value can preferably correspond to a target operating temperature. If areas in the image captured by the camera have a color that is identical to the color black, it can be determined by the evaluation unit that these areas are at least 100 ° C. and analogously that areas with the color white have a temperature of up to 60 ° C. If the color gradient of the thermochromic material is linear, so that there are color gradations or, in the case of a black-and-white representation, depending on the temperature, grayscale levels can be concluded from the gray levels or from the color gradation, an exact temperature and an exact temperature gradient and these are determined by the evaluation unit.

In addition to the stator 10, as shown in FIG. 1, a rotor 30 which surrounds the stator 10 in the circumferential direction is shown in FIG. 3 and comprises a plurality of magnets 31 and a circumferential sleeve 32. On an inner surface 33 of the sheath 32 facing the stator, an angle scale is provided, which is defined by the space between the

Stator teeth 11 can be captured by imaging. The evaluation unit can determine an angle of rotation position of the rotor 30 relative to the stator 10 using the angle scale recorded by the camera 21, this angle of rotation position for example to reduce the starting current and to correctly control the electric motor, in particular during the Start-up can be used. In addition, the sleeve 32 can also be formed from or coated with the thermochromic material, so that the temperature or the temperature profile can be determined at the section of the rotor 30 recorded in each case by imaging technology. If smoke develops on the stator 10 or on the rotor 30, for example due to overheating, the smoke can also be recorded by the camera 21 so that the evaluation unit can report the smoke development to the engine control unit and, for example, trigger an emergency stop. The temperature fields or degrees of contamination determined can also be passed on to the engine control system and used by it to control the engine.

FIG. 4 shows an alternative embodiment to the stator 10 of FIG. 1. The gaps between the stator teeth 11 are essentially completely filled with the stator windings 12. The components designed as cladding 13 are each arranged together with the respectively associated camera 21 and the respectively associated lighting means 22 between the sections of the stator teeth 11 extending in the circumferential direction U. Immediately adjacent stator windings 12 in an intermediate space between two stator teeth 11 can adjoin one another directly and can be separated from one another, for example, only by a thin separating layer.

FIGS. 5a to 5d show examples 40 of a component taken by a camera at different times. To illustrate the thermochromic effect and the determination of the temperature field, a single heating wire runs along a line 42 in the image plane below the component. First, the entire image-related surface 41 is uncolored in FIG. 5a. Depending on the assigned temperature limits, this has a temperature below 60 ° C, for example. After this Current supply to the heating wire is evaluated at three time intervals from one another by the evaluation unit, which are shown in FIGS. 5b to 5d. The heat emanating from the heating wire heats the component and leads on its surface 41 to a discoloration detected by the camera, which, as can be seen in FIGS. 5b to 5d, spreads further and further in the component. Due to the discoloration together with the position scale 45 provided on the surface, the evaluation unit can determine a temperature profile extending outwards from the center of the image (line 42).

Claims

1. Electric motor with one component, wherein

the component is at least partially formed from a thermochromic material or is provided on its surface (14, 15, 16) with a coating of the thermochromic material and the electric motor has a camera (21) which is designed to detach the surface ( 14, 15, 16) of the component to be recorded by image technology, and

has an evaluation unit which is designed to determine a two-dimensional temperature field along the surface (14, 15, 16) from images captured by the camera (21).

2. Electric motor according to the preceding claim, further comprising an illumination means (22) which is designed to illuminate the surface. 3. Electric motor according to one of the preceding claims, wherein

the component determines a cavity (17) and the surface (14, 15, 16) captured by the camera is an inner surface of the component facing the cavity.

4. Electric motor according to the preceding claims, further comprising

a stator (10) with a plurality of stator windings (12), wherein

A gap is determined between two immediately adjacent stator windings (12) of the plurality of stator windings (12),

the component is arranged in the intermediate space. 5. Electric motor according to the preceding claim, wherein

the component is designed as a cladding (13) which defines the cavity (17) and which has an outer surface facing away from the cavity directly to the neighboring ones

Stator windings (12) adjacent or directly adjacent to them,

the covering (13) is formed from the thermochromic material or is coated with the thermochromic material on an inner surface facing the cavity (17),

the lighting means (22) is designed to illuminate the cavity (17) and the inner surface of the cladding (13) facing the cavity (17),

the camera (21) is designed to capture the cavity (17) and the inner surface of the cladding facing the cavity (17) using imaging technology.

6. The electric motor according to the preceding claim further comprising a rotor (30) rotatable about the stator (10), the cavity (17) determined by the casing (13) being open in the radial direction (R) towards the rotor (30) and the camera (21) is designed to record the rotor (30) using imaging technology.

7. Electric motor according to the preceding claim, wherein

On an inner surface (33) of the rotor (30) facing the stator (10) there is an angular scale encircling the stator (10) in the circumferential direction (U), which can be detected by the camera (21) and points or sections of the rotor ( 30) assigns a relative angle of rotation relative to the stator (10). 8 Electric motor according to one of the preceding claims, wherein the camera (21) is designed to capture the surface (14, 15, 16) of the component in terms of image technology and color and

the evaluation unit is designed to assign colors in the images of the surface (14, 15, 16) recorded by the camera (21) to temperature values and the two-dimensional temperature field along the surface from the temperature values assigned to the surface (14, 15, 16) (14, 15, 16) to determine the component.

9. Electric motor according to one of the preceding claims, wherein the two-dimensional temperature field determined by the evaluation unit is a scalar field, in which each point of the surface (14, 15, 16) of the component detected by the camera (21) is assigned a temperature value.

10. Electric motor according to one of the preceding claims, wherein the evaluation unit is further formed from the

Camera (21) captured images to determine a degree of contamination of the surface and / or a state of the surface (14, 15, 16) or the component.

11. Electric motor according to one of the preceding claims, wherein on the surface (14, 15, 16) a temperature-resistant color scale

(19) is provided, which can be detected by the camera (21) and assigns certain colors to certain temperatures, wherein

a color is assigned to a temperature or temperature limit. 12. Electric motor according to one of the preceding claims, wherein on the surface (14, 15, 16) a position scale (18) is provided, which can be detected by the camera (21) and points or sections on the surface each have a specific position. assigns value.

13. A method for detecting a two-dimensional temperature field along a surface (14, 15, 16) of a component, wherein

the component is at least partially formed from a thermochromic material or is provided on its surface with a coating made of the thermochromic material,

the surface (14, 15, 16) is formed by the thermochromic material to change color depending on a component temperature on the surface (14, 15, 16),

A camera (21) is provided, which captures the surface (21) of the component and the images captured by the camera (14, 15, 16) are transmitted to an evaluation unit,

the evaluation unit assigns colors from the images of the surface (14, 15, 16) to temperature values and determines the two-dimensional temperature field along the surface (14, 15, 16) of the component from the temperature values assigned to the surface (14, 15, 16).

14. A method for detecting a two-dimensional temperature field on a stator winding (12) of an electric motor, a component being arranged on the stator winding (12) and wherein

the component is at least partially formed from a thermochromic material or is provided on its surface (14, 15, 16) with a coating of the thermochromic material,

a camera (21) is provided which covers the surface (14,

15, 16) of the component and the images recorded by the camera (21) are transmitted to an evaluation unit,

the evaluation unit colors from the images of the surface (14, 15, 16) assigns temperature values and, from the temperature values assigned to the surface (14, 15, 16), determines the two-dimensional temperature field along the surface (14, 15, 16) of the component and is determined by the two-dimensional temperature field of the stator winding (12).

15. The method according to the preceding claim, wherein

the electric motor comprises a stator (10) with a plurality of stator windings (12) and the component is arranged as a covering (13) in an intermediate space between two stator windings (12) arranged directly next to one another and directly to the stator windings arranged next to one another ( 12) is adjacent to or adjacent to these and

the evaluation unit assigns colors from the images of the surface (14, 15, 16) to temperature values and from the temperature values assigned to the surface (14, 15, 16) the two-dimensional temperature field along the surface (14, 15, 16) of the component and through it a two-dimensional temperature field of the respective stator winding (12) is determined for each of the two stator windings (12) arranged directly next to one another.