GB2261517A - Apparatus for measuring at least one state variable of a rotating body - Google Patents

Apparatus for measuring at least one state variable of a rotating body Download PDF

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Publication number
GB2261517A
GB2261517A GB9223895A GB9223895A GB2261517A GB 2261517 A GB2261517 A GB 2261517A GB 9223895 A GB9223895 A GB 9223895A GB 9223895 A GB9223895 A GB 9223895A GB 2261517 A GB2261517 A GB 2261517A
Authority
GB
United Kingdom
Prior art keywords
rotating body
hall
temperature
output voltage
effect element
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB9223895A
Other versions
GB9223895D0 (en
Inventor
Juergen Maass
Helmut Meyer
Jurgen Seeberger
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Heidelberger Druckmaschinen AG
Original Assignee
Heidelberger Druckmaschinen AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Heidelberger Druckmaschinen AG filed Critical Heidelberger Druckmaschinen AG
Publication of GB9223895D0 publication Critical patent/GB9223895D0/en
Publication of GB2261517A publication Critical patent/GB2261517A/en
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
    • G01K7/36—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using magnetic elements, e.g. magnets, coils
    • G01K7/38—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using magnetic elements, e.g. magnets, coils the variations of temperature influencing the magnetic permeability
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K13/00—Thermometers specially adapted for specific purposes
    • G01K13/04—Thermometers specially adapted for specific purposes for measuring temperature of moving solid bodies
    • G01K13/08—Thermometers specially adapted for specific purposes for measuring temperature of moving solid bodies in rotary movement
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
    • G01P3/42—Devices characterised by the use of electric or magnetic means
    • G01P3/44—Devices characterised by the use of electric or magnetic means for measuring angular speed
    • G01P3/48—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage
    • G01P3/481—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage of pulse signals
    • G01P3/487—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage of pulse signals delivered by rotating magnets

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Transmission And Conversion Of Sensor Element Output (AREA)
  • Measuring Magnetic Variables (AREA)
  • Measuring Temperature Or Quantity Of Heat (AREA)

Abstract

At least one state variable, particularly the temperature, of a rotating body 1 is measured by providing the body with at least one surface region consisting of a permanently magnetic material whereby the magnetic field of the permanently magnetic material is impressed on the output voltage of an adjacent Hall-effect element 5, and a logic unit determines the temperature of the rotating body from the output voltage of the Hall-effect element. The magnetic regions are provided by ferrimagnetic material chosen for its variation of magnetic field with temperature, and may be in the form of a disc 3 attached to the end face of rotor 1 and having segments 6 of alternate magnetic polarity. Alternatively a ferrite plastic strip 4 wrapped around the rotor may be used. It is envisaged that rotor speed and direction may also be determined. <IMAGE>

Description

Apparatus for measuring at least one state variable of a rotating body The invention relates to an apparatus for measuring at least one state variable of a rotating body.
Wherever rotating bodies play a part in a technical field, there is usually an interest in obtaining information about their operating states, e.g.
temperature, rotational speed and/or direction of rotation. Unintentional or uncontrolled variations in one of these operating-state variables constitute a problem whenever there is a demand for a high degree of precision in machining processes by means of rotating bodies or in machining and manufacturing processes on rotating bodies. Thus, in work that has to be performed with precision, dimensional changes in the rotating body as a result, for example, of variations in temperature represent sources of error which sometimes lead to considerable losses in quality.
This is to be explained below with reference to an example from the field of printing. In multi-colour printing presses, a sheet passing through the printing press is printed consecutively with different colours in the individual printing units. There is an increase in temperature in the printing press during the printing process. This increase in temperature will depend, for example, on what proportion of the area of the sheet is to be printed with a printing ink.- This proportion will determine the quantities of printing ink and damping solution supplied, with differences in the application of ink and damping solution between the individual printing units resulting in different interactions between ink and damping solution and the cylinders of the printing press.The resultant temperature differences in the individual printing units will lead to different degrees of expansion of the cylinders and of the printing plates. This results in register errors, which detract from the quality of the printed product.
In order to prevent such temperature-related printing errors, the publication JP-A 64-72846 describes a method for cooling the plate surface in a printing press. The temperature of the plate surface is measured by means of an IR detector which is disposed in the immediate vicinity of the plate surface. If said temperature sensor registers an increase in the temperature of the plate surface, cold air is blown onto the surface of the plate through a nozzle device. The supply of air can be controlled according to the change in temperature.
The object of the present invention is to create an apparatus with which to measure at least one state variable, particularly the temperature, of a rotating body.
The object of the invention is achieved in that the rotating body comprises at least one surface region consisting of a permanently magnetic material, in that at least one Hall-effect element is disposed in such a manner with respect to the rotating body that the magnetic field of the permanently magnetic material is impressed on the output voltage from the Hall-effect element and in that a logic unit determines the temperature of the rotating body by means of the output voltage from the Hall-effect element.
Said apparatus makes use of the physical effect whereby, below the Curie temperature Tc, the magnetic field of permanently magnetic materials is heavily temperaturedependent. As the temperature rises, the permanently magnetic field of such materials is weakened by the increasing thermal agitation of the atoms until, at the Curie temperature Tc, it disappears entirely.
The magnetic properties of permanently magnetic materials are temperature-dependent in completely different ways. The Curie temperature Tc, too, is a material-specific variable. Since, in operating and manufacturing processes, the likely changes in temperature are broadly known, it is possible to select a permanently magnetic material that is heavily temperature-dependent in the expected range. This allows a high degree of resolution to be obtained for the purpose of determining the temperature with the maximum possible accuracy.
According to an advantageous further development of the apparatus according to the invention, it is proposed that the surface region or surface regions consist of ferrimagnetic material. Ferrimagnetic material behaves completely differently in alternating fields from ferromagnetic material, with its electrical resistance being greater by several powers of ten than the resistance of ferromagnetic materials. Consequently, with ferrimagnetic materials, the electrical eddy currents are so small that they can virtually be neglected. Surface regions consisting of ferrimagnetic material are therefore preferred for use in detecting the state variables of a rotor in a motor.
A further development of the apparatus according to the invention provides that the permanently magnetic material is applied to the surface of the rotating body.
In particular, such a surface region (or surface regions) is disposed on a plastic strip applied to the circumference of the rotating body.
According to an embodiment of the apparatus according to the invention, a plurality of surface regions, but at least two surface regions, are provided over the circumference of the rotating body, with any two juxtaposed regions being of different polarity.
The application of an adhesive tape over the circumference of the rotating body will be practical only if the rotating body has a smooth surface. If this is not the case, it is proposed, in a further embodiment of the apparatus according to the invention, that a disc-shaped element is attached to the end face of the shaft of the rotating body, said element comprising a plurality of, but at least two, individual disc segments, with two successive disc segments being of different polarity.
According to the invention, a logic unit determines the temperature of the rotating body on the basis of the output voltage from the Hall-effect element. In a further development of the invention, it is provided that the characteristic curves of the output voltage of the Hall-effect element as a function of temperature are stored in a memory associated with the logic unit and the logic unit determines the temperature of the rotating body by comparing the measured output voltage from the Hall-effect element with the stored characteristic curves. With regard to such measurements of the magnetic field by means of a Hall-effect element, it must always be ensured that the Hall-effect element is not operated in the saturation state.According to the strength of the magnetic field of the permanently magnetic material and depending on the temperature of the rotating body, it is possible, for example by varying the distance between the Hall-effect element and the rotating body, to weaken the magnetic field to such an extent that the above requirement is always satisfied. For this purpose, the stored characteristics must take account not only of the temperature-dependence of the magnetic properties, but also the dependence of the magnetic properties on the distance between the Hall-effect element and the rotating body.
According to a further alternative possibility for determining the temperature of the rotating body, it is proposed that the logic unit compares the measured maximum or minimum output voltage from the Hall-effect element with the stored output voltage from the Halleffect element in a defined initial state and that then, by means of stored characteristic curves, the logic unit determines from the difference of the output voltages a temperature change of the rotating body with respect to said initial state.
However, the apparatus according to the invention can be used not only to determine the temperature of the rotating body. With reference to the maximum (maxima), minimum (minima) and/or zero crossing(s) of the output voltage of the Hall-effect element (output voltages of the Hall-effect elements) per revolution, it is readily possible for the logic unit to determine the rotational speed of the rotating body. Of course, the accuracy of such a measurement of rotational speed will increase with the number of output signals detected per revolution by the Hall-effect element, i.e. it will increase.with the number of permanently magnetic surface regions applied to the circumference of the rotating body.
If, instead of one Hall-effect element, two Hall-effect elements are positioned at a certain angular interval with respect to the circumference of the rotating body, it is possible, e.g. from the relative positions of the output voltages from the Hall-effect elements, for the logic unit to determine the direction of rotation of the rotating body.
The apparatus according to the invention can be used, therefore, not only for the measurement of temperature.
Through minor modifications, it is possible to obtain information on the rotational speed and direction of rotation of the rotating body. Whereas conventional methods of measuring the operating states of rotating bodies require at least two detectors, namely a temperature detector and a rotational-speed detector, one single apparatus is sufficient for this purpose according to the present invention. The apparatus itself is cheap and simple to install and operate.
The apparatus according to the invention is described in greater detail with reference to the drawings, in which: Fig. la shows a cylindrical rotating body, to the end face of which is attached a disc, said disc comprising a plurality of permanently magnetic surface regions; Fig. lb shows a top view of the permanently magnetic disc; Fig. 2a shows a cylindrical rotating body, to the circumference of which is applied a plastic strip, said plastic strip comprising at least one permanently magnetic surface region; Fig. 2b shows a top view of the plastic strip according to Fig. 2a; Fig. 3 shows the output signals from a Hall-effect element as a function of time and temperature and Fig. 4 shows a circuit arrangement for the evaluation of the output signals from the Hall-effect elements.
Fig. la shows a cylindrical rotating body 1, to the end face or shaft 2 of which is attached a ferrimagnetic disc 3. Said ferrimagnetic disc 3 comprises a plurality of segments 6 over its circumference, with each two juxtaposed segments 6 being of different polarity. A Hall-effect element 5 is disposed in such a manner with respect to the ferrimagnetic disc 3 that, during the rotation of the rotating body 1, the output voltage UH from the Hall-effect element 5 is influenced periodically by the different polarities of the magnetic fields of the ferrimagnetic disc 3.
Fig. lb shows a top view of the ferrimagnetic disc according to Fig. la.
Fig. 2a shows a cylindrical rotating body 1, to the circumference of which is applied a ferrite plastic strip 4 consisting of a plurality of surface regions 6, with each two successive surface regions 6 being of different polarity. Once again, a Hall-effect element 5 is provided for measuring the magnetic field of the ferrite plastic strip 4.
Fig. 2b shows a top view of the ferrite plastic strip 4 according to Fig. 2a.
Fig. 3 shows the output signal Ug from the Hall-effect element 5 as a function of time t for two different temperatures T1, T2. As can be seen from this graph, the output voltage UK(t) from the Hall-effect element 5 is higher at the lower temperature Ti, characterizing, for example, the initial state, than at the higher temperature Tz. As already described above, this reduction in the output voltage is attributable to the weakening of permanently magnetic fields at higher temperatures. By a comparison of the differential output voltages Uax(T1) and Umax(T2) with correspondingly stored characteristic curves it is possible to determine the respective temperature of the rotating body 1.
Fig. 4 shows a circuit arrangement for the evaluation of the output signals Uz from the Hall-effect elements 5.
The output voltages UR1 and UH2 from two Hall-effect elements 5 are supplied to an evaluation apparatus 7.
The digitized signals are sent to a microprocessor 9 via an A/D converter 8. Said microprocessor 9 is supplied via signal lines 10 with information on the sign of the measured output voltages UHi and UR2 from the Halleffect elements 5. In the aforedescribed manner, the microprocessor 9 calculates from said measured data the temperature T, the rotational speed n and the direction of rotation of the rotating body 1.
It will of course be understood that the present invention has been described above purely by way of example, and modifications of detail can be made within the scope of the invention.

Claims (12)

CLAIMS:
1. Apparatus for measuring at least one state variable of a rotating body wherein the rotating body comprises at least one surface region consisting of a permanently magnetic material, at least one Hall-effect element is disposed in such a manner with respect to the rotating body that the magnetic field of the permanently magnetic material is impressed on the output voltage from the Hall-effect element, and a logic unit determines the temperature of the rotating body by means of the output voltage from the Halleffect element.
2. Apparatus according to claim 1 wherein the surface region (the surface regions) consists (consist) of a ferrimagnetic material.
3. Apparatus according to claim 1 or 2 wherein the permanently magnetic material is applied to the surface of the rotating body.
4. Apparatus according to claim 1 wherein a multiplicity of surface regions is provided over the circumference of the rotating body, with each two successive surface regions being of different polarity.
5. Apparatus according to claim 4 wherein the surface regions are disposed on a plastic strip.
6. Apparatus according to claim 1 wherein a disc-shaped element is attached to the end face of the shaft of the rotating body, said element being subdivided into a multiplicity of individual disc segments, with each two successive disc segments being of different polarity.
7. Apparatus according to claim 1 wherein the rotating body comprises at least two juxtaposed surface regions, said surface regions being of different polarity.
8. Apparatus according to claim 1, 4, 6 or 7 wherein the characteristic curves of the output voltages of the Halleffect element as a function of temperature are stored in a memory associated with the logic unit and the logic unit determines the temperature of the rotating body by comparing the measured output voltage from the Hall-effect element with the stored characteristic curves.
9. Apparatus according to claim 1, 4, 6 or 7 wherein the logic unit compares the measured maximum or minimum output voltage from the Hall-effect element with the stored maximum or minimum output voltage from the Hall-effect element in a defined initial state and, with reference to stored characteristic curves, determines from the difference of the output voltages a temperature change of the rotating body with respect to said initial state.
10. Apparatus according to claim 1, 4, 6 or 7 wherein the logic unit determines the rotational speed of the rotating body on the basis of the minima, maxima and/or zero crossings of the output voltage of the Hall-effect element per revolution.
11. Apparatus according to claim 7 wherein the logic unit determines the direction of rotation of the rotating body via the relative positions of the output voltages from the Hall-effect elements.
12. Apparatus for measuring at least one state variable of a rotating body substantially as hereinbefore described with reference to the accompanying drawings.
GB9223895A 1991-11-15 1992-11-13 Apparatus for measuring at least one state variable of a rotating body Withdrawn GB2261517A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE4137558 1991-11-15

Publications (2)

Publication Number Publication Date
GB9223895D0 GB9223895D0 (en) 1993-01-06
GB2261517A true GB2261517A (en) 1993-05-19

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GB9223895A Withdrawn GB2261517A (en) 1991-11-15 1992-11-13 Apparatus for measuring at least one state variable of a rotating body

Country Status (3)

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JP (1) JPH05223652A (en)
FR (1) FR2683900A1 (en)
GB (1) GB2261517A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20180086199A1 (en) * 2016-09-23 2018-03-29 Röchling Automotive SE & Co. KG Magnetic field based detection of the operating status of air flap

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015186271A (en) * 2014-03-20 2015-10-22 セイコーエプソン株式会社 Temperature detection device, driving device, and electric motor control method

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1194233A (en) * 1966-09-05 1970-06-10 Licentia Gmbh Temperature Measuring Device
GB1353040A (en) * 1970-10-02 1974-05-15 Unelec Rotary device having a thermal overload detector
GB1369658A (en) * 1970-08-20 1974-10-09 Unelec Systems for detecting thermal overloads in a rotary member
EP0231410A1 (en) * 1986-02-03 1987-08-12 Leybold Aktiengesellschaft Method and circuit for measuring and displaying a physical quantity
EP0242625A1 (en) * 1986-04-25 1987-10-28 Siemens Aktiengesellschaft Measuring device associating a measured value to a measured unit, and measuring probe therefor
WO1989007247A1 (en) * 1988-02-06 1989-08-10 Robert Bosch Gmbh Combined rotational speed/temperature measuring device

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3205460A1 (en) * 1982-02-16 1983-02-03 Martin 7430 Metzingen Graser Contactless, feedback-free temperature measurement using permanent magnet, calibration curve and Hall generator
JPS6326532A (en) * 1986-07-18 1988-02-04 Honda Motor Co Ltd Magnetic signal generating ring
US4987415A (en) * 1989-09-18 1991-01-22 The Torrington Company High resolution encoder
EP0448062B1 (en) * 1990-03-21 1994-02-16 Mannesmann Kienzle GmbH (HR B1220) Direction sensing tachometer

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1194233A (en) * 1966-09-05 1970-06-10 Licentia Gmbh Temperature Measuring Device
GB1369658A (en) * 1970-08-20 1974-10-09 Unelec Systems for detecting thermal overloads in a rotary member
GB1353040A (en) * 1970-10-02 1974-05-15 Unelec Rotary device having a thermal overload detector
EP0231410A1 (en) * 1986-02-03 1987-08-12 Leybold Aktiengesellschaft Method and circuit for measuring and displaying a physical quantity
EP0242625A1 (en) * 1986-04-25 1987-10-28 Siemens Aktiengesellschaft Measuring device associating a measured value to a measured unit, and measuring probe therefor
WO1989007247A1 (en) * 1988-02-06 1989-08-10 Robert Bosch Gmbh Combined rotational speed/temperature measuring device

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20180086199A1 (en) * 2016-09-23 2018-03-29 Röchling Automotive SE & Co. KG Magnetic field based detection of the operating status of air flap
US10953740B2 (en) * 2016-09-23 2021-03-23 Röchling Automotive SE & Co. KG Magnetic field based detection of the operating status of air flap

Also Published As

Publication number Publication date
FR2683900A1 (en) 1993-05-21
JPH05223652A (en) 1993-08-31
GB9223895D0 (en) 1993-01-06

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