DE102008058538A1 - Giant magnetoresistance sensor for detection of magnetic material, has sensor element and temperature sensor element arranged in sensor housing with multilayered structure, where elements are enclosed by embedding layer - Google Patents

Abstract

The sensor (1) has a sensor element (10) for detecting a magnetic material, and a temperature sensor element (11) for detecting temperature. The elements are arranged in a sensor housing (2) with a multilayered structure, which has a conclusion layer (4) and an embedding layer (5). The elements are enclosed by the embedding layer. The conclusion layer has a spring rigidity, which is smaller than a spring rigidity of housings of the elements. A bias magnet is provided for detection of ferrite material. Independent claims are also included for the following: (1) a method for setting-up of a giant magnetoresistance (GMR) sensor (2) a facility device for setting-up of a GMR sensor.

Description

The The invention relates to a GMR sensor for detecting magnetic material, a method for setting up such a GMR sensor and a Equipment device.

Sensors for detecting a magnetic material are manufactured in different techniques. With a simple design, reed switches are used, while other sensors are based on Hall elements. GMR sensors use a so-called GMR effect (giant magnetoresistance) of a GMR element. The advantage of using GMR elements is their high sensitivity to the previously mentioned techniques of reed switches and Hall elements. For example, this describes DE 19739550 C1 a so-called bias magnetization in a multilayer system of a magnetoresistive sensor element having at least one harder bias layer and a non-magnetic intermediate layer arranged therebetween.

Another important feature is the detection of ferritic materials by using a magnet to generate a magnetic bias and use of sensor elements for evaluation. Examples for illustration are the writings US 20050280411 A1 . US 5818685 A and US 5883763 A describing the use of bias magnets and the detection of ferritic material when using GMR elements. Such sensors are often used when scanning tooth flanks or structured steel disks to detect rotational speeds.

When disadvantageous it is seen that in numerous designs existing sensors usually for operation up to a temperature of + 80 ° C are suitable.

Farther At a sampling high demands for tightness of the sensor, resistance to external Media and high temperature requirements. Furthermore are influences of temperature on the sensing elements and to consider the realization of a high switching distance. In addition, a high accuracy should be guaranteed.

It Therefore, the object of the present invention, an improved GMR sensor and a device method or apparatus for to provide this GMR sensor, the above disadvantages of State of the art are significantly reduced.

The The object is achieved by a GMR sensor having the features of the claim 1 solved. The object is further achieved by a method for Setting up such a sensor according to claim 16 and an apparatus solved according to claim 21.

Accordingly, FIG a GMR sensor for detecting magnetic material, the following: at least one sensor element for detecting magnetic material and at least one temperature sensor element for detecting a temperature, wherein the at least one sensor element and the at least one temperature sensor element in a sensor housing with a multilayer structure, the at least one finishing layer and an embedding layer has, arranged and surrounded by the embedding layer.

Herewith It is advantageously possible to place the sensor in one area for detecting magnetic material in a high-environment environment Temperature to use, with the application range of -25 ° C. extends to + 120 ° C.

By the use of the temperature sensor element can disadvantages be avoided by temperature drift of the sensor element.

With a biasing magnet is an additional detection of Ferritic material advantageously possible. It can do that Output signal of the sensor element with threshold values for the switching on and off of the sensor are compared, whereby the Operation of the sensor is defined.

Especially in liquid or gaseous media is a good heat transfer to the sensor element for Detection of ferritic material given.

to Detection of high-resolution ferritic materials the sensor element may be stronger in temperature stressed area of the sensor are positioned. When temperature changes comes it due to the different thermal expansion coefficients to mechanical stresses that affect the life of the sensor can. By the GMR sensor according to the invention is the sensor element against shock and vibration in practical use protected, as far as the temperature sensor element is concerned, which may be a thermocouple, for example. Other versions are of course possible. With this temperature detection is a temperature compensation of a signal of the sensor element for sensing ferritic material in the vicinity the measuring point possible, where also the temperature measurement takes place.

In the area of the measuring point, the sensor element is encapsulated so that mechanical stresses due to thermal expansion act in a homogeneous manner on a housing of the sensor element. Mechanical shear stresses on the surface of the sensor element are thus avoided. This is done, for example, by the embedding area which surrounds the sensor element and is for example a gel-like substance. This embedding layer is closed to the outside by another layer, a final layer, which has a high mechanical resistance and a high chemical resistance to media that may occur at the measuring point. On the other hand, it has a lower rigidity than the embedding layer. Upon thermal expansion of the potting layer, namely the gelatinous layer, the overcoat layer yields such that the pressure in the potting layer remains below a specified limit dictated by the sensor element for detecting magnetic and / or ferritic materials. This finishing layer can be made, for example, of metal with resilient properties, of plastic or of potting material in a defined thickness and shape or of a multilayer composite material. The cover layer may also include a pressure compensation element, for example a membrane.

In A further embodiment provides that the finishing layer forms a strain relief for a supply of the GMR sensor and / or has. It can also be a part of the sensor housing be.

A further advantageous property of the gelatinous embedding layer This is the effect of shock and vibration on the sensor to dampen.

Of the GMR sensor can be a control unit for evaluating the signals of the at least one sensor element and the at least one temperature sensor element exhibit. In this case, the control unit in the finishing layer be integrated or included. The signal of the temperature sensor element can from this control unit separately next to the signal of the sensor element to be provided. The evaluation is preferred in the control unit, which is equipped with a controller, for example, performed. But it is also possible that the evaluation the magnetic changes detected by the sensor element takes place in the sensor element itself.

One The output of the GMR sensor can be configurable, for example in Reference to current or voltage or NPN or PNP function or turn as normally closed or normally open function.

The Switching outputs and / or analogue outputs of the GMR sensor can during a setup process of the GMR sensor with signals be acted upon, which characterize the setup process, wherein these signals to identify a setup area with invalid or unsafe values have pre-definable waveforms.

In an alternative embodiment is provided that the at least one sensor element and the at least one temperature sensor element are arranged on a sensor circuit board. This is in preferred Version with a control unit on a control board via a flexible connection board connected. Thus, the Orientation of the sensor element to a scanning of the Sensors are ensured.

The Control unit may at least one storage device for storage an evaluation program, wherein the evaluation program of a Mounting the control unit in the sensor housing or after a disassembly in the storage device is reloadable.

One high temperature range for the overall configuration for GMR sensors with temperature sensors and sensor elements for Detection of magnetic or ferritic materials by a at least two-layered or multi-layered structure within achieved the sensor. Here are components to ensure the tightness and mechanical stability in the outer Layers combined with materials used for thermal stabilization and thermal coupling to the sensory relevant scanning serve. This can, for example, in the casting by at least two-layer encapsulation in a metal or metal housing another hard-wearing material. Injection a supply line (cable) to the thermally compensated unit advantageous.

The Realization of a high accuracy over the temperature can by depositing the temperature response of the sensor element take place in conjunction with the temperature sensor element, which in the Sensor is integrated. For this purpose, the control unit with a controller serve as an evaluation unit, wherein the temperature response, for example is stored as a table in a memory.

The magnetic compensation of the sensor housing is possible within the sensor element or an evaluation unit. In this case, the magnetic influence of stainless steels or other weakly ferritic housing materials can be compensated. This compensation operation can be done by a setup process that is carried out in production or installation in an environment in which ferritic material is present. The compensation can be done regularly by the Evaluation unit are performed to counteract an accumulation of ferritic material in the vicinity of the sensor. For this purpose, the control unit may be designed accordingly, for example.

The Evaluation circuit, for example, the control unit, a message signal if the compensation function is at the end of a modulation range of the sensor element approaches to an adjustable threshold. The mechanical setpoints of the sensor can be adjusted be executed, with the setting using the evaluation he follows. To activate the setting process, a special magnet matched to the sensor can be used. Another Adjustment is through the use of signaling over given the outputs or the supply line. It can do that Defining and saving a switching threshold by means of a defined Coding be made, which via an actuation on the connection cables (supply line). As operating possibilities can apply defined voltages outside the typical operating voltage range carried out above or well below the operating voltage become. Another way of signaling arises through the defined impressing of currents. The Signaling is preferably done in coded form, so that a protection against unintentional parameterization is achieved.

A Setup device for carrying out the method for Setup can be done with an adjustment device, which codable Electro and / or permanent magnets, done. It can the Adjustment means a marker for indicating a direction of a have to be set switching point.

The Invention will now be described with reference to embodiments With reference to the accompanying drawings explained in more detail. Hereby shows:

1 a schematic side view with function blocks of a first embodiment of a GMR sensor according to the invention;

2 a schematic sectional view along line AA according to 1 ;

3 a schematic sectional view of a variation of the first embodiment along line AA after 1 ;

4 a schematic sectional view of a further variation of the first embodiment along line AA after 1 ;

5 a schematic sectional view of a still further variation of the first embodiment along line AA after 1 ;

6 a schematic side view of the first embodiment in a setup process; and

7 a schematic side view with function blocks of a second embodiment of the GMR sensor according to the invention.

Same Components or functional units with the same function are with the same reference numerals in the figures.

In 1 is a schematic side view with function blocks of a first embodiment of a GMR sensor according to the invention 1 , The GMR sensor 1 has a sensor housing 2 with a supply side and an opposite end face, wherein an upper side facing a lower side and the underside as a Abtastseite 3 of the sensor 1 is trained. The sensor housing 2 here is rectangular in longitudinal section and, for example, cuboid. Other designs, for example cube-shaped, are possible.

Inside the sensor housing 2 There is a multi-layered structure, which is two-layered in this example. Under the top is a finishing layer 4 arranged, which is down to the scan side 3 an embedding layer 5 connects, in which close to the Abtastseite 3 a sensor element 10 and a temperature sensor element 11 are embedded. These sensor elements 10 and 11 are from the embedding layer 5 , which is gelatinous here, enveloped. These sensor elements 10 and 11 can also be called primary elements.

In the final shift 4 is a control unit 7 arranged, which via a supply line connection 12 with a supply line 6 connected to the sensor housing 2 is appropriate. The supply line 6 May be in the finishing layer 4 be injected or in a strain relief (not shown) on the sensor housing 2 or in the finishing layer 4 be attached.

The control unit 7 is with the sensor element 10 via a sensor element connection 13 and connected to the temperature sensor element via a temperature sensor element terminal. The control unit 7 supplies the sensor elements 10 and 11 with electrical energy from the supply line 6 which is fed from outside. Furthermore, the control unit receives 7 Signals of the sensor element 10 which is a GMR sensor element in response to sampled magnetic and / or ferritic materials evaluates these signals, for example based on stored table values and outputs corresponding output signals, for example "ON", "OFF" via the supply line 6 to a higher-level control as signals 20 out. Signals of the temperature sensor element 11 evaluates the control unit 7 for temperature compensation of the sensor element 10 with and fits, for example by means of stored table values or suitable compensation algorithms, the signals of the sensor element 10 accordingly.

2 illustrates a schematic sectional view taken along line AA according to 1 , Here encloses the sensor housing 2 , for example metal, finishing layer 4 and the embedding layer 5 laterally. The scan side 3 may have an additional protective layer or from the sensor housing 2 be formed. In this embodiment, the GMR sensor 1 intended for scanning or detection of magnetic materials.

For ferritic materials, sampling is possible if the variation is 3 with a bias magnet 8th who is here in the final shift 4 is used. The sensor housing 2 is not shown with. The bias magnet 8th is preferably a permanent magnet that generates a magnetic field that is the sensor element 10 penetrates and is changed by ferritic (also magnetic) material so that this change from the sensor element 10 is palpable. Here its output signal with thresholds for switching the sensor on and off 1 compared and so the operation of the sensor 1 Are defined.

The embedding layer 5 is gel-like and can expand when heated by the ambient temperature. It is advantageous that the top layer 4 has a spring stiffness that is less than that of the sensor housing 2 and the housing is in which the sensor elements 10 and 11 are arranged. It is preferred that the spring stiffness is smaller by a factor of at least 0.1 than the spring stiffness of one of the housing of the sensor elements 10 and 11 , 4 shows a variation in which a pressure compensation element 9 , for example a membrane, in the finishing layer 4 is used, here on the border between finishing layer 4 and embedding layer 5 ,

In another variation, the 5 in section along the line AA 1 shows are the sensor elements 10 and 11 on a sensor PCB 15 applied, which here parallel to the scan side 3 in the sensor housing 2 is arranged. Perpendicular to this is a control circuit board 17 with the control unit 7 (for example, a controller with memory blocks) positioned. An elastic connection between the sensor PCB 15 and the control board 17 is through a connection board 16 formed, which is for example a flexible circuit board.

6 shows a schematic side view of the first embodiment in a setup. Below the GMR sensor 1 is on the scan side 3 a setup device with an adjusting device 18 with two permanent magnets 19 . 19 ' arranged. These magnets can also be controllable electromagnets.

Furthermore, the polarity or coding of the permanent magnets 19 . 19 ' be adjusted, for example by twisting. The magnets 19 . 19 ' activate a setup process of the sensor 1 , Their coding can be used to decide which switching point, for example in the control unit 7 , is taught. The adjustment device 18 may have a mark indicating the direction of the switching point to be established. Thus, the newly set switching point can be selected. The sensor 1 can be designed so that during a set-up one or more or all switching points can be set up. By operation with the adjusting device 18 can the evaluation unit or control unit 7 the teaching of the switching points in a fixed sequence or according to the coding in the adjusting device 18 existing magnets 19 . 19 ' carry out.

7 finally illustrates a schematic side view with function blocks of a second embodiment of the GMR sensor according to the invention 1 , In this embodiment, the scanning surface 3 not below the sensor housing 2 but at the front. Other variations are of course conceivable.

The The invention is not limited to the embodiments described above limited. It is included in the attached Claims modifiable.

It is conceivable, for example, that the finishing layer 4 with the sensor housing 2 combined or part of it.

The circuit boards 15 . 16 and 17 can also consist of a complete flexible printed circuit board.

A program for the evaluation unit or control unit 7 can be in the sensor before mounting 1 or fed in after removal. It may also be possible, this programming from the outside via the supply line by means of certain signals / waveforms or wireless, z. B. via radio, induction coil or infrared make.

1

GMR sensor

2

sensor housing

3

scanning side

4

topcoat

5

buried layer

6

supply

7

control unit

8th

magnet

9

Pressure compensation element

10

sensor element

11

Temperature sensor element

12

supply connection

13

Sensor element Connection

14

Temperature sensor element Connection

15

Sensor circuit board

16

Connecting board

17

Control board

18

adjusting

19 19 '

permanent magnet

20

signal

N, S

North / South Pole

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• DE 19739550 C1 [0002]
• US 20050280411 A1 [0003]
• US 5818685 A [0003]
• - US 5883763 A [0003]

Claims (22)

GMR sensor ( 1 ) for detecting magnetic material, with at least one sensor element ( 10 ) for detecting magnetic material and with at least one temperature sensor element ( 11 ) for detecting a temperature, wherein the at least one sensor element ( 10 ) and the at least one temperature sensor element ( 11 ) in a sensor housing ( 2 ) having a multilayered structure comprising at least one finishing layer ( 4 ) and an embedding layer ( 5 ) and arranged by the embedding layer ( 5 ) are surrounded. GMR sensor ( 1 ) according to claim 1, characterized in that the GMR sensor ( 1 ) a bias magnet ( 8th ) for additional detection of ferritic material. GMR sensor ( 1 ) according to claim 1 or 2, characterized in that the at least one finishing layer ( 4 ) has a spring stiffness which is less than a spring stiffness of housings of the at least one sensor element ( 10 ) and the at least one temperature sensor element ( 11 ). GMR sensor ( 1 ) according to claim 3, characterized in that the at least one finishing layer ( 4 ) has a spring stiffness, which by a factor of at least 0.1 lower than the spring stiffness of housings of the at least one sensor element ( 10 ) and the at least one temperature sensor element ( 11 ). GMR sensor ( 1 ) according to one of the preceding claims, characterized in that the finishing layer ( 4 ) has high mechanical resistance and high chemical resistance. GMR sensor ( 1 ) according to one of the preceding claims, characterized in that the finishing layer ( 4 ) a pressure compensation element ( 9 ) having. GMR sensor ( 1 ) according to one of the preceding claims, characterized in that the finishing layer ( 4 ) a strain relief for a supply line ( 6 ) of the GMR sensor ( 1 ) forms and / or has. GMR sensor ( 1 ) according to one of the preceding claims, characterized in that the finishing layer ( 4 ) a component of the sensor housing ( 2 ). GMR sensor ( 1 ) according to one of the preceding claims, characterized in that the at least one sensor element ( 10 ) and the at least one temperature sensor element ( 11 ) on a sensor circuit board ( 15 ) are arranged. GMR sensor ( 1 ) according to one of the preceding claims, characterized in that the GMR sensor ( 1 ) a control unit ( 7 ) for evaluating the signals of the at least one sensor element ( 10 ) and the at least one temperature sensor element ( 11 ) having. GMR sensor ( 1 ) according to claim 10, characterized in that the control unit ( 7 ) on a control board ( 17 ) is arranged, the at least one sensor element ( 10 ) and the at least one temperature sensor element ( 11 ) on a sensor circuit board ( 15 ), wherein the control circuit board ( 17 ) and the sensor circuit board ( 15 ) are connected by means of a flexible connecting circuit board. GMR sensor ( 1 ) according to claim 10 or 11, characterized in that the control unit ( 7 ) has at least one memory device for storing an evaluation program, wherein the evaluation program of an assembly of the control unit ( 7 ) into the sensor housing ( 2 ) or after disassembly into the storage device is reloadable. GMR sensor ( 1 ) according to one of the preceding claims, characterized in that switching outputs and / or analog outputs of the GMR sensor ( 1 ) during a setup process of the GMR sensor ( 1 ) Be aufschlagt with signals be that are indicative of the setup process, these signals for identifying a Einrichtbereiches with invalid or unsafe values have previously definable signal forms. GMR sensor ( 1 ) according to one of the preceding claims, characterized in that the GMR sensor ( 1 ) can be used for a temperature range of -25 ° C to + 120 ° C. GMR sensor ( 1 ) according to one of the preceding claims, characterized in that the embedding layer ( 5 ) is formed gel-like. Method for setting up a GMR sensor ( 1 ) according to one of the preceding claims, wherein compensating switching points of the GMR sensor ( 1 ) is performed by means of magnetic fields by at least one external magnet. A method according to claim 16, characterized in that during a set-up one or more switching points of the GMR sensor ( 1 ) are set according to a coding of the magnetic fields. Method for setting up a GMR-Sen sors ( 1 ), compensating switching points of the GMR sensor ( 1 ) is performed by means of electrical signals by at least one external electrical or electronic control. A method according to claim 18, characterized in that during a set-up one or more switching points of the GMR sensor ( 1 ) are set up in a pre-definable sequence. Method according to one of claims 16 to 19, characterized in that the GMR sensor ( 1 ) a GMR sensor ( 1 ) according to any one of claims 1 to 15. Device for the implementation of the method according to one of claims 14 to 16, with an adjusting device ( 18 ), which encodable electric and / or permanent magnets ( 19 . 19 ' ) having. A device according to claim 21, characterized in that the adjusting device ( 18 ) has a mark for indicating a direction of a switching point to be set.