CN102003248A - Method for measuring lubricating oil level and sensor - Google Patents

Abstract

The invention relates to a method for measuring lubricating oil level and a lubricating oil level sensor. The oil level is measured through the impedance change of a straight electric heating wire, namely the electric heating wire is excited by alternating current or direct current to emit heat, and the temperatures of the electric heating wire in two media, namely air and lubricating oil, are different, so the resistance of the electric heating wire changes with the position of the oil, and the lubricating oil level is determined according to the change law of the resistance. In the lubricating oil level sensor, the straight electric heating wire and a power amplifier for providing the alternating current or direct current to heat the electric heating wire are arranged on a framework; amplitude stabilized alternating current is adopted; and a sine wave generator outputs an amplitude stabilized signal at a certain frequency at the front end of the power amplifier, so the pressure drop of the two ends of the electric heating wire changes with the oil level linearly and quasilinearly, the resistance of the straight electric heating wire correspondingly changes with the pressure drop of the two ends of the corresponding electric heating wire, and the resistance of the electric heating wire is measured.

Description

A kind of method of lubricated oil-level measurement and sensor

Technical field

The present invention relates to a kind of method and sensor of lubricated oil-level measurement.It is machinery lubricant oil level measuring arrangement.

Background technique

The sensor kind of measuring the lubricant oil position is more, and equipment adopts the mode of measuring indirectly mostly.The conventional ball float that all has drives measuring transducer or spot measurement, and measured by factors such as installing space restriction or lubricating oil viscosity are big unreliable because of ball float, and spot measurement can't form the continuous on-line monitoring.But the lubricant oil position transducer of simple installation continuous measurement has extensive market prospects.

Summary of the invention

The objective of the invention is to propose a kind of method of lubricated oil-level measurement and detect mechanical equipment lubrication oil oil level device, it is the lubricant level sensor, can realize journey highi degree of accuracy continuous measurement in a small amount, volume simple in structure is little, can be applicable to mini-plant and complicated lubricant oil liquid level measurement environment.

Technical solution of the present invention is: the method for lubricated oil-level measurement, it is characterized in that changing impedance measurement oil level by the electric heating wire of a straight line shape, promptly by an alternating current (a.c.) or direct current (d.c.) excitation electrothermal wire heating, the temperature of electric heating wire in air and lubricant oil two media there are differences, therefore the resistance of electric heating wire also changes along with the position of oil, determines lubricated oil level according to the changes in resistance rule.

The lubricant oil level sensor, on a skeleton, be provided with the straight line shape electric heating wire, provide alternating current (a.c.) or direct current (d.c.) (as the 100mA alternating current (a.c.)) that electric heating wire is heated by power amplifier, frequency is fixed on a certain frequency when adopting the fixed ampllitude alternating current (a.c.) when using alternating current (a.c.), frequency range is not limit (as 1Hz), the power amplifier front end is exported the fixed ampllitude signal of a certain frequency such as 1Hz frequency by a sine-wave generator, be provided with the circuit of the resistance of measuring electric heating wire, the height of the corresponding lubricated oil level of the resistance sizes of electric heating wire, the heating back has changed the resistance of electric heating wire according to oil and air two media weak heat-dissipating, therefore the pressure drop at electric heating wire two ends is along with the height linearity or the almost of oil level change, pressure drop size according to corresponding electric heating wire two ends, the resistance of straight line shape electric heating wire also should have size mutually, by measuring the resistance of electric heating wire, when AC measurment, convert d. c. voltage signal to and come measuring resistor, also can be transformed into current signal as required by rectifying and wave-filtering.The present invention can also be used for the fuel level sensor of the oil product of other insulation and safety.The pressure drop at electric heating wire two ends is along with the height linearity or the almost of oil level change (can calibrate through CPU), because of electric heating wire dispels the heat in air than weak heat-dissipating in oil, then the thermal resistance of electric heating wire is big as weak heat-dissipating, the pressure drop at corresponding electric heating wire two ends is big, by measuring the resistance of electric heating wire, when AC measurment, convert d. c. voltage signal to and come measuring resistor, also can be transformed into current signal as required by rectifying and wave-filtering.The present invention can also be used for the fuel level sensor of the oil product of other insulation and safety.

Electric heating wire is resistance wire, and is commonly used as constantan wire, chromium-copper silk; Corresponding resistance and lubricated oil level result's corresponding relation is: resistance is littler, and lubricant level is lower.

Described straight line shape electric heating wire is a straight line shape electric heating wire or a pair of straight line electric heating wire of secured in parallel, and a pair of straight line electric heating wire of secured in parallel is an electric heating wire, is wound on the skeleton.Be wound on the skeleton, the straight line shape electric heating wire adopts a pair of straight line electric heating wire of secured in parallel better, and single electric heating wire also needs lead to constitute the loop, also can take the electric heating wire of N root parallel winded, certainly, adopts the even number root convenient in wiring.

The invention has the beneficial effects as follows: the lubricant oil position transducer that the present invention proposes, but by precision high and the easiest realization resistance measurement continuous measurement lubricant oil position (only need constantly take out signal at output port gets final product), it is more directly perceived to compare traditional spot measurement method, but the live signal teletransmission is to end instrument or management system.Smaller size smaller and advanced metering system can be applicable to complex environment.It is simple in structure in the present invention, the reliability height, to the end instrument circuit require lowly, on-site installation and maintenance are easy, and are easy to use.

Description of drawings

Fig. 1 is a structural representation of the present invention.

Fig. 2 is a measuring circuit block diagram of the present invention (schematic diagram).

Embodiment

The specific embodiment of the present invention is as follows:

Fundamentals of Sensors be (Fig. 1) by fixing an electric heating wire 1 on the skeleton, be connected to functional circuit in the metal protection shell, the cable ejector is arranged on the shell, install and fix sensor adopt threaded screw all can, the electric heating wire part is formulated length according to the fuel tank degree of depth.

Fig. 2 is the sensor measuring circuit schematic diagram, secured in parallel one electric heating wire on a skeleton, provide the 100mA alternating current (a.c.) that electric heating wire is heated by power amplifier, fixed-frequency is at 1HZ, the power amplifier front end is by the fixed ampllitude signal of sine-wave generator output 1HZ, the heating back has changed the resistance of electric heating wire according to oil and air two media weak heat-dissipating, therefore the pressure drop at electric heating wire two ends is along with the height linear change of oil level, convert direct current signal to by rectifying and wave-filtering again, also can be transformed into current signal as required.

Lubricant oil sensor of the present invention is taked novel design, the thermal resistance of electric heating wire is transformed into the level gauging signal, become (4 ~ 20mA) ac current signals that send back output industrial standard, the invention solves the technological gap of lubricant oil continuous measurement, small volume simple structure application area is wider.

1, getting alloy resistance wire 100mm is fixed on the insulation framework, two ends are stretching with resistance pin welding back, unsettled on skeleton body, be carved with scale on the skeleton, 18.2 ohm of test sensor D.C. resistances, input voltage 10VDC, steady current 100mA, lubricant oil sae30 packs in the transparent measuring cup, ambient temperature 25C °, the measuring transducer both end voltage is in being exposed to air: 2.45VDC, and insert fully and side is housed in the lubricant oil must be 1.87 VDC, insert in the lubricant oil by every 10mm and record sensor both end voltage (table 1) respectively.

2, provide the 100mA alternating current (a.c.) that electric heating wire is heated by power amplifier, fixed-frequency is at 1HZ, the power amplifier front end is by the fixed ampllitude signal of sine-wave generator output 1HZ, and alternating voltage peak-to-peak value 20VAC is by recording sensor both end voltage (table 1) respectively in every 10mm insertion lubricant oil.

3, lubricant oil level sensor of the present invention, electric heating wire places in the container of the oil that needs measurement, be provided with sine wave generating circuit and power generator or constant0current generator, the output of power generator or constant0current generator connects electric heating wire, and the measuring circuit of resistance is that rectification circuit is that (transmission circuit among the figure) is to the input/output port of measuring through signal amplification circuit and tension measuring circuit.

4, described sine wave generating circuit is a custom circuit, can be conventional CR oscillation circuit, the sine wave generating circuit that also can adopt microprocessor to produce.Power generator or constant0current generator are constand current amplification circuit (as common-base amplification circuits), the output of power generator or constant0current generator connects electric heating wire, the measuring circuit of resistance is that the voltage measurement to the resistance wire two ends realizes, by the diode bridge rectifier with through signal amplification circuit resistance two terminal voltages are measured, transmission circuit among the figure is to the input/output port of measuring, input/output port connects a microprocessor, can be calibrated (the corresponding curve of determining resistance and voltage under the uniform temperature) according to the measured value of voltage by microprocessor.

5, as adopting DC electrical source, can realize by an electric bridge the sampling of the resistance measurement on the electric heating wire.Electric bridge by routine can high-precision measuring resistor.

Table 1

Insertion depth mm	Measuring voltage VDC	Measuring voltage VAC
			0	2.451	1.733
10	2.407	1.702
			20	2.347	1.659
30	2.287	1.617
			40	2.220	1.570
50	2.163	1.529
			60	2.101	1.485
70	2.041	1.443
			80	1.977	1.398
90	1.922	1.359
			100	1.871	1.323

According to measurement result, the electric heating wire two ends are Linearity error slightly, finds it is that fixedly the metal leg of electric heating wire causes by analyzing the back, and two ends are reserved 5mm and can be avoided measurement error in the practical application.

The electric heating wire of straight line shape described in the figure 1 is a pair of straight line electric heating wire of secured in parallel, and the even number root all is desirable schemes, and a pair of straight line electric heating wire of secured in parallel is an electric heating wire, is wound on the strip skeleton.The straight line shape electric heating wire that is wound on a skeleton can place in the sleeve pipe 2 other sign among the figure: sensor outer housing 3, lighting outlet 4, lubricant oil 5.

Claims (6)

1. lubricate the method for oil-level measurement, it is characterized in that changing impedance measurement oil level by the electric heating wire of a straight line shape, promptly by an alternating current (a.c.) or direct current (d.c.) excitation electrothermal wire heating, the temperature of electric heating wire in air and lubricant oil two media there are differences, therefore the resistance of electric heating wire also changes along with the position of oil, determines lubricated oil level according to the changes in resistance rule.

2. lubricant oil level sensor, it is characterized in that on a skeleton, being provided with the straight line shape electric heating wire, being provided with power amplifier provides alternating current (a.c.) or direct current (d.c.) that electric heating wire is heated, adopt the fixed ampllitude alternating current (a.c.) when using alternating current (a.c.), the power amplifier front end is exported the fixed ampllitude signal of a certain frequency by a sine-wave generator, be provided with the circuit of the resistance of measuring electric heating wire, the height of the corresponding lubricated oil level of the resistance sizes of electric heating wire, the heating back has changed the resistance of electric heating wire according to oil and air two media weak heat-dissipating, therefore the pressure drop at electric heating wire two ends is along with the height linearity or the almost of oil level change, pressure drop size according to corresponding electric heating wire two ends, the resistance of straight line shape electric heating wire also should have size mutually, by measuring the resistance of electric heating wire.

3. lubricant oil level sensor according to claim 2 is characterized in that converting d. c. voltage signal to by rectifying and wave-filtering when AC measurment comes measuring resistor.

4. lubricant oil level sensor according to claim 2, it is characterized in that described straight line shape electric heating wire be a straight line shape to N root electric heating wire, N is an integer, parallel winded is on a skeleton.

5. lubricant oil level sensor according to claim 2 is characterized in that described a pair of straight line electric heating wire is wound on the skeleton.

6. lubricant oil position measuring sensor according to claim 2, it is characterized in that electric heating wire places in the container of the oil that needs measure, be provided with sine wave generating circuit and power generator or constant0current generator, the output of power generator or constant0current generator connects electric heating wire, and the measuring circuit of resistance is that rectification circuit is to the input/output port of measuring through signal amplification circuit and tension measuring circuit.

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