CN104792252B - Displacement sensor - Google Patents
Displacement sensor Download PDFInfo
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- CN104792252B CN104792252B CN201510030424.7A CN201510030424A CN104792252B CN 104792252 B CN104792252 B CN 104792252B CN 201510030424 A CN201510030424 A CN 201510030424A CN 104792252 B CN104792252 B CN 104792252B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/0005—Geometrical arrangement of magnetic sensor elements; Apparatus combining different magnetic sensor types
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/007—Environmental aspects, e.g. temperature variations, radiation, stray fields
- G01R33/0082—Compensation, e.g. compensating for temperature changes
Abstract
A kind of displacement sensor is provided.Antiresonant circuit (4) including coil (6) and capacitor (8,10) is set to the outlet side of NPN transistor (12), the output of antiresonant circuit 4 is fed back to the input side of transistor (12), to constitute the colpitts oscillation circuit (2) constantly vibrated.The output level of transistor (12) changes according to measured object relative to the variation of the position of coil (6).Constant-current source (26) constantly provides DC current to coil (6).RC low-pass filter (30) pressure drop caused by the DC current because flowing through coil (6) is come the variation of the DC resistance of detection coil (6).Microprocessor (38) adjusts the output level of transistor (12) based on the output of RC low-pass filter (30).
Description
Technical field
It is the present invention relates to a kind of displacement sensor of change in location for detecting measured object using coil, in particular to right
Error caused by resistance value variation with temperature based on coil compensates.
Background technique
As the displacement sensor using coil, such as there are eddy current type displacement sensors.Eddy current type displacement sensor benefit
It uses following principle: when coil of the electric conductor as measured object close to circulation alternating current, flowing through electric conductor and produce
Raw alternating current magnetic field, thus the impedance of coil changes.In the eddy current type displacement sensor, the impedance of coil is also according to using
The temperature change of environment and change, it is therefore desirable to impedance variations caused by the temperature change are compensated.In Japanese Unexamined Patent Publication
An example of the compensation technique is disclosed in clear 60-67819 bulletin (patent document 1).
In upper displacement sensors, exchange is produced from coil carrying out the alternating current of self-oscillator to coil offer
In the state of magnetic field, the size vortex different according to the change in location of measured object is induced in coil.Based on according to whirlpool
The size of stream and the output voltage of coil that changes detect the displacement of measured object.In the output electricity that coil like this is utilized
Pressure changes with the variation of the position of measured object in the displacement sensor of this point, when the output voltage of coil is with surrounding
The variation of temperature and when changing, the displacement of measured object cannot be correctly detected, need to carry out temperature-compensating.As defined in every process
Sampling period just provides unit to coil offer DC current to replace alternating current from DC current, and utilizes DC voltage
Detector come detect due to the DC current from coil export DC voltage.It is single by correction based on the DC voltage detected
The alternating current that first opposite direction coil provides is controlled, with the output voltage to coil with the electricity based on temperature change of coil
Variation caused by change in resistance is corrected.
In upper displacement sensors, it is necessary to carry out the alternating current of self-oscillator to coil offer, therefore in addition to coil with
Also need to be arranged oscillator outside, circuit structure becomes complicated.In addition, it is desirable to be cut to alternating current with what DC current switched over
Switch, control switching circuit are changed, circuit structure becomes more complicated, and is not suitable for the displacement sensor being set to installation space small
Place.In addition, every just provide DC current to coil to carry out temperature-compensating by defined sampling period, therefore in the temperature
The detection that can not be displaced during degree compensation.For example, being needed constantly in the case where detecting the displacement of valve of internal combustion engine
The detection being displaced is not available the displacement sensor of patent document 1.
The purpose of the present invention is to provide one kind can not only simplify circuit structure, can also carry out temperature-compensating one on one side
Constantly detect the displacement sensor of displacement in side.
Summary of the invention
The displacement sensor of one embodiment of the present invention has the auto-excitation type oscillating unit constantly vibrated.Auto-excitation type vibration
It swings unit and has parallel resonance unit and amplifying unit, which includes coil and capacitor.Above-mentioned parallel resonance
Unit is set to the outlet side of amplifying unit, and the output of above-mentioned parallel resonance unit is fed back to the input side of amplifying unit.?
In the auto-excitation type oscillating unit, the output level of above-mentioned amplifying unit according to measured object relative to the variation of the position of coil and
Variation.In the case where eddy current type displacement sensor, position of the output level of amplifying unit with measured object relative to coil
The variation set and change.As the mode of oscillation of oscillating unit, it is able to use so-called LC oscillation, for example examines biez
(Colpitts) type oscillation, the oscillation of Hartley (Hartley) type, general (Clapp) the type oscillation of carat, collector tuning type counter coupled
Oscillation, the oscillation of tuned-base type counter coupled and their deformation type, other well known various modes of oscillation.Direct current provides unit
Direct current signal is constantly provided to above-mentioned coil.Resistance value detection unit is drawn according to because of the above-mentioned direct current signal for flowing through above-mentioned coil
Pressure drop detect above-mentioned coil DC resistance variation.The DC resistance of above-mentioned coil with ambient enviroment temperature
Degree changes and changes.Control unit adjusts the output electricity of above-mentioned amplifying unit based on the output of above-mentioned resistance value detection unit
It is flat.
In the displacement sensor constituted as described above, the oscillating unit of auto-excitation type is used, therefore can simplify
Circuit structure.Also, using the auto-excitation type oscillating unit constantly vibrated, and constantly to the coil of auto-excitation type oscillating unit
Direct current signal is provided, therefore does not need to stop the oscillation of auto-excitation type oscillating unit for detection resistance value, it can be constantly
Detection displacement.
Above-mentioned direct current can be provided to unit to be set as providing the constant-current source of constant current to above-mentioned coil.In this case, above-mentioned
Resistance value detection unit is the filter unit of the DC voltage generated in the above-mentioned coil of detection.
When being configured to this structure, only flip-flop is detected by filter unit, can not be by the shadow of alternating component
It rings and detection resistance value.
In the above method, it can make above-mentioned amplifying unit that there is active component, which has first electrode extremely
Third electrode changes the conductive shape between first electrode and third electrode according to the signal between first electrode and second electrode
State.In this case, the current adjustment unit being set between first electrode and second electrode is carried out by above-mentioned control unit
Control.As active component, such as it is able to use bipolar junction transistor (bipolar transistor) or field effect transistor.
It, can be by the electricity between the first electrode for flowing through active component and third electrode when being configured to this structure
Stream is controlled to adjust the gain of oscillating unit, and as a result, it is possible to carry out the temperature-compensating of coil, and auto-excitation type oscillation is single
Member keeps stable oscillatory regime.
Detailed description of the invention
Fig. 1 is the circuit diagram of the displacement sensor of an embodiment of the invention.
Fig. 2 is the figure of the relationship of the measured object and coil in the displacement sensor for indicate Fig. 1.
Fig. 3 is the figure for indicating the variation of the resistance value of the coil of displacement sensor of Fig. 1.
Specific embodiment
The displacement sensor of an embodiment of the invention is, for example, eddy current type displacement sensor, as shown in Figure 1
With auto-excitation type oscillating unit, such as colpitts oscillation circuit 2.Colpitts oscillation circuit 2 has parallel resonance unit, for example simultaneously
Join resonance circuit 4.The antiresonant circuit 4 is to be connected in parallel the series circuit of two capacitors 8,10 and coil 6.
For the antiresonant circuit 4, to make the antiresonant circuit 4 select coil 6, electricity in a manner of defined frequency parallel resonance
The value of container 8,10.Also, colpitts oscillation circuit 2 also has active component, such as bipolar junction transistor, is specially NPN brilliant
Body pipe 12.NPN transistor 12 includes first electrode, such as base stage；Second electrode, such as emitter；And third electrode, example
Such as collector.Not shown biasing (bias) circuit provides bias appropriate to the NPN transistor 12.Also, NPN transistor
12 are connect by capacitor (not shown) with reference potential, such as earthing potential, for example to carry out as grounded-base circuit
Movement.
One end of antiresonant circuit 4 is connect with earthing potential, and the other end of antiresonant circuit 4 is via direct-current blocking-up electricity
Container 14 and connect with the collector of NPN transistor 12.The emitter of transistor 12 is connected to capacitor 8 and capacitor 10
Interlinkage.Thus, the output generated between the base-collector junction connected by capacitor (not shown) with high-frequency mode
A part is fed back to emitter side.Collector via include impedor load 16 and with power supply terminal, for example positive electricity
Source terminal 18 connects, and collector is also connect with output terminal 20.In addition, emitter is via a part for forming above-mentioned biasing circuit
Current adjustment unit, such as variable current source 22 and connect with earthing potential.
The frequency of oscillation that the colpitts oscillation circuit 2 is determined with the parallel resonance frequency by antiresonant circuit 4 is constantly
Oscillation, oscillation output are removed from output terminal 20.As shown in Fig. 2, when measured object, the valve 24 of the engine of such as ship
When position relative to coil 6 changes, is for example close, as illustrated in association with conventional art, the resistance of coil 6
It is anti-to change, so that the level of the oscillation output generated at output terminal 20 changes.Not shown detection unit is come
The variation of the level is detected, to detect the displacement of valve 24.
As shown in figure 3, the intrinsic resistance value of the resistance value of coil 6, valve 24 changes with the temperature change of ambient enviroment,
If therefore ignoring this, the level of the oscillation output from output terminal 20 can change, and cannot correctly detect
The displacement of valve 24.In the environment of 100 degree or more of temperature is especially changed to below zero centigrade in ambient temperature, the oscillation
The level of output significantlys change.Therefore, in this embodiment, direct current provides one end of unit, such as constant-current source 26 and coil 6
Connection.One end of the constant-current source 26 is connect with positive power supply terminal, and the other end of the constant-current source 26 is connect with one end of coil 6.
Direct current signal, such as DC current from the constant-current source 26 constantly flow to earthing potential via coil 6.To prevent the direct current
DC blocking capacitor 14 is provided with for the purpose of collector of current direction NPN transistor 12 etc..
When there are the temperature change of ambient enviroment, the resistance value of coil 6 changes, because of the direct current from constant-current source 26
Electric current and the value of DC voltage generated between the both ends of coil 6 change.In order to detect the DC voltage, in coil 6
Both ends between be connected with resistance value detection unit, such as low-pass filter 30.Low-pass filter 30 is, for example, including resistor
32 and capacitor 34 RC low-pass filter.It is to prevent to detect colpitts oscillation circuit 2 using low-pass filter 30
Oscillator signal.The output signal of the low-pass filter 30 is provided to control unit, example after for example being amplified by dc amplifier 36
Such as microprocessor 38.In microprocessor 38, digitize the output signal of dc amplifier 36, to the digital output signal into
Row correction keeps it in a linear relationship with temperature.Digital output signal after the correction is compared with pre-determined a reference value
Compared with, such as be compared with as the corrected value at a temperature of benchmark, to generate control signal.The control signal, which is provided to, to be set
It is placed in the variable current source 22 of the emitter of NPN transistor 12, to control the electric current drawn from the emitter of NPN transistor 12,
The electric current sucked by collector is controlled in turn.Thereby, it is possible to make at output terminal 20 generate oscillation output level not by
The influence of ambient temperature and carry out displacement measurement in the state of keeping linear.For example, defeated when making to vibrate to the offer of NPN transistor 12
When level out becomes 1.2 times of electric current, the level that output is vibrated in the entire stroke of the desired measurement of valve 24 is also almost
1.2 times, keep linear relationship.
Such as in the case where the temperature of ambient enviroment is higher than fiducial temperature and the resistance value of coil 6 becomes larger, oscillation output
Level becomes smaller, therefore increases oscillation energy by making the electric current of variable current source 22 become larger, and oscillation output level is thus made to become larger.
Conversely, ambient enviroment temperature lower than fiducial temperature and the resistance value of coil become smaller to vibrate output become larger when, make can be changed
The electric current of current source 22 becomes smaller to make to vibrate output level and become smaller.Moreover, the current value of variable current source 22 and oscillation output electricity
There are linear relationship between flat, microprocessor becomes easy the control of variable current source 22.
In this way, even if there are the temperature changes of ambient enviroment, the output level of displacement sensor can also be carried out
Temperature-compensating.Moreover, the temperature-compensating is not carried out every the defined time, it is continued for, therefore can be critically
Temperature-compensating is carried out, and does not need to stop the oscillation of oscillating circuit 2 to carry out temperature-compensating.Thus, it is possible to constantly
Detection displacement, so as to critically detect displacement.For example, can. while using thermistor etc. to carry out temperature-compensating
Constantly detection displacement, still, in this case, number of components increases, and the structure of displacement sensor becomes complicated, except this with
Outside, the increase of the failure rate and number of components of displacement sensor correspondingly increases, thus thermistor etc. using unsatisfactory.
In addition, the variation for oscillation level caused by temperature, is carried out by increasing and decreasing the oscillation level of oscillator
Correction, but be corrected in the following manner: by being input in mlultiplying circuit as multiplying for oscillator
One, another is set as coefficient based on temperature.But not only circuit becomes complicated, cost also rises.In contrast, exist
In this displacement sensor, collector current, therefore energy are changed to change emitter current by control variable current source 22
Enough output levels for changing oscillator signal in the state of stablizing oscillatory regime, therefore circuit structure is simple, in terms of cost
Also advantageous.
The present invention is implemented to eddy current type displacement sensor in the above-described embodiment, but also can to other types,
Such as differential transformation type displacement sensor implements the present invention.The displacement of valve 24 is had detected in the above-described embodiment, but it is unlimited
In this, displacement sensor of the invention can be used in the displacement for detecting other measured objects.In addition, in above embodiment
In used colpitts oscillation circuit 2, but not limited to this, is also able to use well known self-excited oscillation circuit, such as carat
General oscillating circuit, Hartley oscillation circuit etc..In addition, having used NPN transistor 12 in the above-described embodiment, but also can
Use PNP transistor, additionally it is possible to use FET.In addition, acting NPN transistor 12 in a manner of base earth, but also can
Act it with emitter earthing mode.RC low-pass filter 30 has been used in the above-described embodiment, but also can
It is enough to use the active low-pass filter that operational amplifier, resistor and capacitor is utilized, additionally it is possible to use LC low-pass filtering
Device.Variable current source 22 is used as current adjustment unit in the above-described embodiment, but will can also be constituted as follows
Structure is used as current adjustment unit: the emitter of one end of resistor and NPN transistor being connected, the other end of resistor is passed through
It is grounded by variable voltage source.Or also it can constitute current adjustment unit in the following way: by the transmitting of NPN transistor 12
Pole is grounded via emitter resistor, adjusts electric current by changing base voltage.Micro process is used in the above-described embodiment
Device 38 digitizes the output of dc amplifier 36 to control variable current source 22, but can also constitute are as follows: amplifies direct current
The output of device 36 is offered as desired the linearity circuit constituted in an analog fashion, and the output of the linearity circuit is provided
To the comparator constituted in an analogue form, the output of the comparator is provided to variable current source 22.
Claims (2)
1. a kind of displacement sensor, has:
Auto-excitation type oscillating unit comprising parallel resonance unit and amplifying unit, the parallel resonance unit include coil and capacitor
The resistance value of device, the coil changes according to the variation of ambient temperature, which is set to the defeated of the amplifying unit
Side out, the output of above-mentioned parallel resonance unit are fed back to the input side of the amplifying unit, the output level of above-mentioned amplifying unit
Changed according to measured object relative to the variation of the position of above-mentioned coil, and the output level of above-mentioned amplifying unit also according to
The temperature change of the resistance value of above-mentioned coil and reduce amplification；
Direct current provides unit, constantly provides direct current signal to above-mentioned coil；
Resistance value detection unit, caused by the above-mentioned direct current signal because flowing through above-mentioned coil pressure drop detect above-mentioned coil
Resistance value temperature change；And
Control unit increases and decreases the output level of above-mentioned amplifying unit based on the output of above-mentioned resistance value detection unit, with
The variation that the output level of above-mentioned amplifying unit caused by temperature change to the resistance value of above-mentioned coil reduces amplification carries out
Compensation,
Wherein, above-mentioned amplifying unit has active component, which has first electrode to third electrode, according to the first electricity
Signal between pole and second electrode changes the conduction state between first electrode and third electrode,
The current-variable unit being set between second electrode and reference potential is controlled by above-mentioned control unit.
2. displacement sensor according to claim 1, which is characterized in that
It is to provide above-mentioned coil the constant-current source of constant current that above-mentioned direct current, which provides unit, and above-mentioned resistance value detection unit is that detection is above-mentioned
The filter unit of the DC voltage generated in coil.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811104935.9A CN109373881A (en) | 2014-01-21 | 2015-01-21 | Displacement sensor |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2014008498A JP6403247B2 (en) | 2014-01-21 | 2014-01-21 | Displacement sensor |
| JP2014-008498 | 2014-01-21 |
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| CN201811104935.9A Division CN109373881A (en) | 2014-01-21 | 2015-01-21 | Displacement sensor |
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| CN104792252A CN104792252A (en) | 2015-07-22 |
| CN104792252B true CN104792252B (en) | 2019-05-03 |
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| CN201811104935.9A Pending CN109373881A (en) | 2014-01-21 | 2015-01-21 | Displacement sensor |
| CN201510030424.7A Active CN104792252B (en) | 2014-01-21 | 2015-01-21 | Displacement sensor |
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| JP (1) | JP6403247B2 (en) |
| KR (2) | KR101744698B1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP7185872B2 (en) | 2018-10-16 | 2022-12-08 | ナブテスコ株式会社 | Displacement sensor |
| JP7260871B2 (en) | 2018-10-16 | 2023-04-19 | ナブテスコ株式会社 | Displacement sensor |
| CN109557858B (en) * | 2018-12-10 | 2020-11-03 | 中国航发南方工业有限公司 | RVDT conversion circuit and electronic controller |
| CN114440753B (en) * | 2022-02-24 | 2022-11-22 | 电子科技大学 | Non-contact displacement measuring device based on eddy current principle |
| JP7296025B1 (en) | 2023-03-13 | 2023-06-21 | 日立Astemo株式会社 | Sensor device and damping force variable suspension system |
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- 2014-01-21 JP JP2014008498A patent/JP6403247B2/en active Active
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2015
- 2015-01-20 KR KR1020150009410A patent/KR101744698B1/en active IP Right Grant
- 2015-01-21 CN CN201811104935.9A patent/CN109373881A/en active Pending
- 2015-01-21 CN CN201510030424.7A patent/CN104792252B/en active Active
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| CN103471641A (en) * | 2013-09-03 | 2013-12-25 | 中国科学技术大学 | Method for automatically correcting temperature drift of electrical vortex sensor |
Also Published As
| Publication number | Publication date |
|---|---|
| KR20150087127A (en) | 2015-07-29 |
| CN109373881A (en) | 2019-02-22 |
| KR101853012B1 (en) | 2018-04-30 |
| KR20170067167A (en) | 2017-06-15 |
| KR101744698B1 (en) | 2017-06-08 |
| JP2015137888A (en) | 2015-07-30 |
| JP6403247B2 (en) | 2018-10-10 |
| CN104792252A (en) | 2015-07-22 |
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