JPS6145449Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a pressure transducer that is distributed in water or the like and measures external pressure by highly sensitively detecting minute displacements of diaphragms that are displaced in response to external pressure.

Traditionally, pressure transducers have been of the force-balanced type or displacement-balanced type, and since these are transmitted from the diaphragm to the expansion mechanism via the force beam, they have problems such as friction, including hysteresis, and their sensitivity is naturally limited. It was hot. Furthermore, when used in places where normal power supply is difficult, such as when distributed underwater, it is required that the consumption of the driving power source be as low as possible.

This invention solves the above-mentioned disadvantages, and can detect minute displacements of displacement objects such as diaphragms with high sensitivity.
Moreover, the present invention aims to provide a pressure transducer that consumes less electric power. Next, one embodiment of this invention will be described.

Fig. 1 is an explanatory diagram of the configuration and operation of the pressure transducer of this invention. A magnet piece 3 is fixed to a housing, and two magnetic detection coils 1 and 2 are wound in the same direction (these are core (cored coil) in which the core of the coil is affected by an external magnetic field and its magnetic permeability changes, resulting in a change in the inductance of the coil), and the other end has a A compensating magnet piece 4 having the illustrated polarity that cancels out the magnetic fields of the N and S poles of the magnet piece 3 is fixed in the housing 6 together with the magnetic detection coils 1 and 2. The coils 1 and 2 are excited by an AC power source 9 and are differentially connected to two adjacent sides of the bridge circuit.

In order to make the magnetic detection coils 1 and 2 sufficiently sensitive, it is necessary to increase the amount of magnetization of the detection magnet piece 3. In this case, if the amount of magnetization of the magnet piece 3 is increased, magnetic saturation occurs in the magnetic detection coils 1 and 2, making it impossible to detect the displacement of the magnet piece 3, that is, the displacement of the diaphragm 5. Therefore, the compensating magnet 4 is provided to cancel this magnetic flux and bring the magnetic detection coils 1, 2 to their operating range. In addition, 6 is a housing that accommodates the above-mentioned 1 to 5.

The magnetic detection coils 1 and 2 and the electric resistors 7 and 8 are bridge-connected, and the magnetic detection coils 1 and 2 are excited by an AC power source 9. A circuit connection is made so that the unbalanced voltage at this time is taken out from the output terminal 10. Figure 2 is a characteristic chart of the magnetic detection coil, where the horizontal axis H shows the magnetic field strength, and the vertical axis eo shows the output voltage.At _{both ends} of the magnetic field strength H, the output voltage
eo is saturated. In this device, the magnetic flux ψ ₀ of the detection magnet piece 3 saturates by the magnetic flux ψ 0 of the compensating magnet piece ₄ acting in the opposite direction.
By canceling the magnetic flux ψ ₀ of the detection magnet piece 3, the linear operation region L is also reached. In this state, when the diaphragm 5 is deformed in the vertical directions A and B in the figure due to external pressure, the detection magnet piece 3 fixed to it is displaced, and the number of magnetic fluxes interlinking with the magnetic detection coils 1 and 2 changes, causing the magnetic The inductances of the detection coils 1 and 2 change in opposite directions, and the respective output voltages change in opposite directions.
As a result, since both coils 1 and 2 are differentially bridge-connected, the difference in inductance change between both coils 1 and 2 becomes an output voltage and is taken out from output terminal 10. On the other hand, changes in the magnetic field from the outside (magnetic noise) are different from the magnetic field of the detection magnet piece 3,
Since a magnetic field of the same magnitude in the same direction acts on both detection coils 1 and 2, the inductance of both coils 1 and 2 changes in the same direction, so that magnetic noise is canceled and is not generated as an output of the bridge circuit.
As a result, minute displacements of the detection magnet piece 3, that is, minute displacements of the diaphragm, can be detected with high sensitivity without being affected by magnetic noise.

According to experiments, an output voltage change of about 3 mV was obtained for a displacement of the detection magnet piece (diaphragm) of 0.001 mm, and the current consumption at that time was extremely small at 80 μA.

FIG. 3 is an explanatory perspective view of a pressure transducer according to another embodiment of this invention, in which parts common to those in FIG. There is.

In this case, the detection magnet piece 3 is displaceable in a direction perpendicular to the magnetic flux axes of the magnetic detection coils 1 and 2, and this structure reduces the overall thickness of the transducer to that of the previous embodiment. It can be made thinner than the .
In the case of the above embodiment, correction magnetic poles 11 made of small screws made of magnetically conductive material are provided at the ends of the magnetic detection coils 1 and 2, respectively, and the strength of the compensation magnetic field can be freely adjusted by moving the screws forward and backward. is also possible.

The effect of this device is that it consists of a small magnet piece attached to a diaphragm that is displaced by external pressure, a magnetic detection coil, and a compensation magnet. Since the device is held in place, the device has a simple structure and is easy to assemble, and can detect minute displacements of the diaphragm with high sensitivity without contact.

The pressure transducer of this invention uses a bridge-connected differential detection circuit to eliminate the influence of external magnetic noise and to provide highly sensitive detection capability.

In addition, the power input is small, and when used in places where normal power supply is difficult, such as when used in combination with pressure transducers that are distributed independently in water etc., in addition to the above effects, it has even more excellent functions. can be demonstrated.

Furthermore, in the embodiment, the two detection coils are differentially connected so that they are excited in the same direction, and the detection circuit is a bridge circuit, so it is possible to remove the influence of external noise and extract only a large signal. can.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the configuration and operation of a pressure transducer according to one embodiment of this invention, Fig. 2 is a diagram explaining characteristics of a magnetic detection coil, and Fig. 3 is an explanatory perspective view of another embodiment of this invention. . 1, 2: Magnetic detection coil, 3: Detection magnet piece,
4: Compensating magnet piece, 5: Diaphragm, 6: Housing, 9: AC power supply.

Claims (1)

[Scope of utility model registration request] A magnet piece fixed to the center of the diaphragm so that the north and south poles are arranged along the diaphragm surface in a device that detects the amount of displacement of the diaphragm and measures the pressure acting on the diaphragm;
A compensating magnet is magnetically opposed to each of the N and S poles of this magnet piece, and is fixedly arranged on the housing so as to cancel the magnetic field of this magnet piece, and a compensating magnet is arranged between each of the opposing magnetic poles of these two magnets. , and has two cored magnetic detection coils wound in the same direction, a bridge circuit in which each of the coils is installed on two adjacent sides, and an AC power source for the bridge circuit. A pressure transducer characterized in that an output voltage proportional to displacement is obtained from a circuit, and a linear operation region can be set using the compensation magnet.