RU2202767C2 - Procedure to generate signal across output of inductive pickup with variable magnetic resistance - Google Patents

Abstract

FIELD: testing equipment. SUBSTANCE: procedure can be used in devices which generate electric signal of required form across output of inductive pickup of variable magnetic resistance while pickup is undergoing test as well as in devices and system utilizing such signal. Value of magnetic flux flowing through sensitive element of pickup is changed in accordance with given procedure. Additional magnetic flux is formed in this case and is summed up with inherent magnetic flux of pickup. EFFECT: generation of electric signal in absence of traveling master pickup, reduced energy consumption for generation of this signal. 5 dwg

Description

 The invention relates to testing equipment and can be used to obtain an electrical signal of the desired shape at the output of an inductive sensor of variable magnetic resistance when testing a sensor, as well as a device or system using such a signal.

 Inductive sensors are widely used to control objects with moving parts. The term "inductive sensor" means a primary converter, in which the inductance plays the role of a sensing element.

 Inductive sensors of variable magnetic resistance are known (for example, see MKI 5 G 01 P 1/02, application RP 0394824, publ. 31.10.90, MKI 5 G 01 P 3/488, French application FR 2669736, publ. 05/29/92), the design of which, in addition to inductance, includes a pole pin and a permanent magnet. The magnet is a source of constant magnetic flux penetrating the sensor element.

 It is known the use of inductive sensors of variable magnetic resistance in the engine control system (see MKI 5 G 01 P 1/02, applications WO 94/17417, WO 94/17418, WO 94/17419, publ. 04.08.94), anti-lock system vehicle (see MKI 4 G 01 P 3/481, 60 T 8/32, application FRG OS 3628585, publ. 03.03.88), vehicle security system (see MKI 5 B 60 R 25/04, application WO 94/18037, publ. 08/18/94).

 The sensor is located near the moving part of the control object - the setter, the role of which is played by the ferromagnetic part, for example, the counterweight of the ICE crankshaft (see IPC G 01 M 15/00, patent US 5361630, publ. 08.11.94) or a gear wheel (see MKI5 G 01 P 3/488, application EP 0462435, publ. 12/27/91). When moving the setpoint, the magnetic resistance of the portion of the magnetic circuit of the sensor along which the magnetic flux flows changes. Note that the form of the master determines the shape of the signal received at the output of the sensor. Therefore, in test benches for testing control systems, they usually use exact copies of adjusters, which are driven by an electric drive.

 The presence in the test equipment of the electric drive increases its dimensions, power consumption, leads to noise and vibration.

 A mechanically moving setter can serve as a source of injury to personnel serving the test benches.

 The prototype of the proposed method is a method of obtaining a signal at the output of an inductive sensor of variable magnetic resistance, described in [1], in which the magnetic flux passing through the sensor element is modulated. Modulation of the magnetic flux is carried out by changing the magnetic resistance of the portion of the magnetic circuit along which the magnetic flux of the sensing element flows, due to the movement of the setter, made of ferromagnetic material, using a drive.

 The disadvantages of the prototype are the need for mechanical movement of the setter relative to the sensor and high energy costs for moving the setter.

 The objectives of the invention are to obtain an electrical signal in the sensing element of an inductive sensor of variable magnetic resistance in the absence of a moving master and reducing energy costs for receiving this signal.

 These tasks are solved in a method for producing an electrical signal at the output of an inductive sensor with a variable magnetic resistance, in which the magnitude of the magnetic flux passing through the sensor element is changed.

 The problems are solved by the fact that an alternating magnetic flux, additional with respect to the sensor’s own magnetic flux, is formed by the local source of magnetomotive force and the additional magnetic flux is added to the sensor’s own magnetic flux.

 The invention is illustrated by the following drawings.

 In FIG. 1 shows a structural diagram of a device according to the proposed method.

 Figure 2 presents the sequence of passage under the sensor of the teeth of the setter while rotating the latter.

 In FIG. 3 shows the electrical signal of the sensor during rotation of the setter.

 In FIG. 4 shows the voltage versus time at the output of the switch 4, which allows simulating the rotation of the setter.

 Figure 5 shows the dependence of the current at the output of the shaper 6 from time to time.

 As an example of the implementation of the proposed method, we consider a device that simulates the rotation of the knob of the crankshaft position sensor of the engine ignition and fuel injection control system of an engine shown in German patent DE 4133570 (MKI 5 F 02 D 41/00, publ. 24.12.92). The master is made in the form of a gear disc with many uniform angular marks. A reference mark is provided on the disc, formed by two missing corner marks.

 The inventive method can be implemented using the device shown in Fig. 1 and including a frequency-setting potentiometer 1, a voltage-controlled generator 2 for generating sawtooth pulses corresponding to the gear sector of the setter, a voltage-controlled generator 3 for forming sawtooth pulses, corresponding to the missing teeth of the setter, switch 4, counter-decoder 5, sinusoidal pulse shaper 6, and also current regulator 7 in winding 8 wound on core 9. Potentiometer output RA 1 is connected to the control inputs of the generators 2 and 3. The output of the generator 2 is connected to the first input of the switch 4 and to the counting input of the counter-decoder 5. The output of the generator 3 is connected to the second input of the switch 4. The output of the switch 4 is connected to the input of the sinusoidal pulse generator 6, the output of which, in turn, is connected to the input of the current controller 7 in the inductor 8. The output of the counter-decoder 5 is connected to the control input of the switch 4.

 The device operates as follows. At the output of potentiometer 1, a certain voltage is manually set, which, entering the inputs of generators 2 and 3, causes them to generate sawtooth pulses of a given amplitude and frequency proportional to the applied voltage, and the frequency of generator 3 is two times lower than the frequency of generator 2. These pulses are fed to the inputs switch 4, which, depending on the signal from the output of the counter 5, arriving at its control input, passes sawtooth pulses of generators 2 and 3 to its output. Ator 4 arrive at input 6 sinusoid generator pulses, wherein the pulses are converted into quasisinusoidal. This is necessary in order to ensure a smooth change in the current in the winding 8 to eliminate distortion in the electrical signal generated by the sensor. Quasi-sinusoidal pulses from the output of the shaper 6 are fed to the input of the current regulator 7, which flows through the winding 8 wound on the core 9, and in the latter creates a magnetic flux, uniquely determined by the law of variation of the current in the winding 8 (Ф = K • i (t), where Ф - magnetic flux, К - proportionality coefficient, i - electric current, t - time). The current regulator 7 has a manual adjustment of the current level in the winding 8, simulating the gap between the real inductive sensor of variable magnetic resistance and the master.

 To implement the proposed method perform the following steps.

 An inductive variable magnetic resistance sensor (not shown in FIG. 1) is located in close proximity to the core 9 so that the sensor’s own magnetic flux is added to the magnetic flux caused by the flow of current in the winding 8.

 An alternating magnetic flux is formed by passing current through the winding 8.

 Summarize the additional variable magnetic flux with its own magnetic flux sensor.

 According to the law of induction, a variable magnetic flux causes the appearance of an EMF in the winding of an inductive sensor of variable magnetic resistance, and the law of change of the induced EMF will be determined by a function that is the first time derivative of the function Ф (t), which describes the law of change of the magnetic flux.

Sources of information
1. Automotive sensors. Sat articles. Per. from English Yu.N. Savchenko.- M.: Mechanical Engineering, 1982, p. 54.

Claims (1)

 A method of obtaining an electrical signal at the output of an inductive sensor with a variable magnetic resistance, in which the magnitude of the magnetic flux flowing through the sensor element is changed, characterized in that an additional alternating magnetic flux is formed by an external source of magnetomotive force and the additional magnetic flux is added to the sensor’s own magnetic flux.

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