JPH0712931Y2 - Acceleration detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a detector for detecting the acceleration / deceleration of a moving body such as an automobile by a differential transformer.
The detector of the present invention can be used as another sensor that detects a change in physical quantity with a differential transformer, for example, a position sensor, a tilt sensor, a pressure sensor, or the like, but the following description will be given by taking acceleration detection as an example. Do it.

[Conventional technology]

One of the methods for detecting the acceleration of a moving body is to detect a magnetic body that moves according to the acceleration with a differential transformer and to cause an output change in the secondary coil portion of this transformer according to the amount of displacement of the magnetic body. There is.

FIG. 4 shows the basic structure of a conventional acceleration detector using a differential transformer. In the figure, 41 is a differential transformer 42.
Of the primary coil 43, and 44 and 45 are secondary coils of a differential transformer connected in opposite phases. In this detector, the magnetic body 46 receives acceleration, and two secondary coils
Secondary coil when displaced from the equilibrium point at the center between 44 and 45
The voltages of 44 and 45 change proportionally and the output voltage amplitude on the secondary side increases. Therefore, the output voltage is passed through the amplifier circuit 47, the phase detection circuit 48, and the filter circuit 49, and the processed output is taken out as an acceleration signal.

[Problems to be solved by the device]

This type of conventional detector uses a phase detection circuit to convert the output voltage of the secondary coil section of the differential transformer into a linear output according to the acceleration, which results in a complicated circuit configuration and cost. It has a problem of becoming high.

[Means for Solving the Problems]

In order to solve the above problems, the present invention provides a difference in the number of windings of two secondary coils of a differential transformer.

When the differential transformer has two primary coils, the number of windings of the two primary coils may be different.
However, regardless of whether the difference in the number of windings is applied to the primary coil or the secondary coil, the difference in the number of windings is greater than the output voltage change amount across the secondary coil when the movable magnetic body is in the detectable area. The output voltage due to the difference in the number of windings is set to a large value, and the output voltage due to the difference in the number of windings is generated in advance.

The combined output voltage obtained on the secondary side can be converted into a linear output corresponding to acceleration / deceleration by passing it through a combined output processing circuit having an amplifier circuit, a rectifier circuit, a filter circuit, and the like. The processing circuit used here may perform re-amplification after amplification / rectification as necessary.

[Action]

Input power supply voltage (= primary coil voltage of differential transformer)
Is V ₁ sin2 πft (f is the power supply frequency), and the output voltage generated in the two secondary coils by the magnetic flux of the primary coil is V _2-1 sin2
πft, V _2-2 sin ₂ πft. At this time, if the winding ratio between the two secondary coils is 1: S, the output voltage is V _2-1 sin2πft for one secondary coil and SV for the other secondary coil.
It becomes _2-1 sin 2πft. These output voltages have an acceleration / deceleration of x and a proportional constant of k. One coil has V _2-1 ′ (1 + kx) sin2πft and the other coil has S2.
V _2-1 ′ (1-kx) sin2πft (kx is positive on the side where the movable magnetic body enters and negative on the side where it escapes). Where 2
Since the two secondary coils are connected so as to have opposite phases, the combined output voltage across them is V _2-1 ′ (1-kx) sin2πft −SV _2-1 ′ (1-kx) sin2πft = { a (1-S) + (1 + S) kx)} V 2-1 'sin2πft.

Therefore, if the measurement range of x is -α <x <α, {1-S + (1 + S) kα> 0 and 1-S + (1 + S) k (-α)> 0} or {1-S + (1 + S) kα <0 and 1−S + (1 + S) k (−α) <0} Or If the winding ratio S is set so as to satisfy the equation, the output voltage will always have the same phase within the measurement range, and a linear DC output corresponding to acceleration / deceleration can be obtained simply by rectifying and smoothing without phase detection. You can

Here, the example in which the number of turns of the two secondary coils is made different has been taken as an example, but when a differential transformer having two independent primary coils is used, the two primary coils are Even if the number of turns is different, phase detection can be made useless by the same action.

〔Example〕

FIG. 1 shows an acceleration detector as an embodiment of the present invention. This differential transformer type acceleration detector 1 is configured such that when an acceleration is applied in the direction A in the figure, the leaf springs 3a and 3b are generated in the case 2.
The movable magnetic body 4 supported by elastically deforms each leaf spring and moves in the direction B in the figure. Reference numeral 6 is a primary coil of a differential transformer, and 7a and 7b are secondary coils connected in opposite phases. In this embodiment, regarding the number of windings of the coil, the primary coil 6 is set to 10
00 turns, secondary coil 7a 1000 turns, 7b 1500 turns.

In this way, since the number of turns of the two secondary coils is set to different values, there is a difference in the generated voltage between 7a and 7b even when acceleration is not applied, and the difference is due to the generation of acceleration. Increase or decrease. This increase / decrease value corresponds to the acceleration,
The winding number ratio of 7a and 7b is adjusted so that the voltage value does not become negative even when the differential voltage decreases most in the detectable range.

The voltage difference between the secondary coils is then converted into a DC signal by an output processing circuit (not shown) including an amplification section, a smoothing section, and a filter section, and is taken out as a detector output.

FIG. 2, the DC a representation output, acceleration 0 times voltage V ₀ is generated movable magnetic body 4 is stationary to the balance point of the leaf spring, the value of V ₀ with the occurrence of the acceleration Is increasing or decreasing.

FIG. 3 shows the second embodiment. In the figure, 12 is a case,
Reference numeral 13 indicates a leaf spring. The acceleration detector 11 has a structure in which the primary coil of the differential transformer is separated into two primary coils 16a and 16b, each of which generates a voltage in the secondary coils 17a and 17b. In this embodiment, the number of turns of the secondary coil is set to 1000 turns for both 17a and 17b, and the primary coil 16a
The number of turns was set to 500 turns and 16b to 1000 turns, and the number of turns was made different on the primary coil side.

Also in this case, a signal having the characteristics shown in FIG. 2 can be output without using the phase detection circuit as in the first embodiment.

〔effect〕

As described above, the detector of the present invention has the number of windings of two secondary coils of a differential transformer or, if there are two primary coils, one of the windings of the primary coil and the secondary coil. Since the output voltage that is larger than the output voltage change amount within the detectable range is generated in advance by differentiating the number, phase inversion does not occur during the detection, and therefore, the change in the physical quantity to be detected such as acceleration does not occur. On the other hand, the output processing circuit for obtaining a linear output characteristic can be simplified, which is advantageous in terms of cost.

In addition, the reliability of the output circuit is improved by simplifying the output circuit.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an example of the acceleration detector of the present invention, FIG. 2 is a graph showing the output characteristics of the detector of the embodiment, FIG. 3 is a schematic configuration diagram of another embodiment, and FIG. FIG. 1 is a block diagram showing a schematic configuration of a conventional differential transformer type acceleration detector. 1, 11 ... Accelerometer, 2, 12 ... Case, 3a, 3b,
13 ... Leaf spring, 4, 14 ... Movable magnetic body, 6, 16a, 16b ...
… Primary coil, 7a, 7b, 17a, 17b… Secondary coil.

Claims (2)

[Scope of utility model registration request] 1. A differential transformer detects a movable magnetic body that moves according to acceleration or changes in position, inclination, pressure, etc., and the displacement amount of the movable magnetic body is detected on the secondary side of the transformer. In a detector such as an acceleration that produces a corresponding output, the number of windings of two secondary coils is made different, and the difference is output at both ends of the secondary coil when the movable magnetic body is in the detectable region. A detector for acceleration, etc., characterized in that the output voltage due to the difference in the number of windings is set to a value larger than the voltage change amount. 2. A movable magnetic body that moves in response to acceleration or changes in position, inclination, pressure, etc.
2 of this transformer
In a detector for acceleration or the like that produces an output according to the displacement amount of the movable magnetic body on the secondary side, the number of windings of the two primary coils is made different, and the difference is detected by the movable magnetic body. A detector for acceleration or the like, characterized in that the output voltage due to the difference in the number of windings is set to a value larger than the amount of change in the output voltage across the secondary coil when in the possible range.