JPH0528772B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention comprises a coil, a core that moves within the coil to change the reactance of the coil, and a diaphragm that moves the core according to changes in received pressure. This relates to displacement detectors.

[Conventional technology]

In conventional displacement detectors, a core moving within a coil is supported by a movable member moved by a diaphragm, and is fixed by tightening with a bag-shaped nut screwed into the movable member. This item requires a nut and requires a screwdriver to assemble. In addition, since the nut is bag-shaped and has a larger diameter than the outer diameter of the core, the space between the coil and the core is large, and the reactance of the coil changes slowly as the core moves, resulting in poor detection sensitivity. be.

[Problem that the invention seeks to solve]

The present invention addresses the above-mentioned drawbacks and aims to provide a device with a small number of parts, easy assembly, and high detection sensitivity.

[Means for solving problems]

The present invention provides a displacement detector that includes a coil, a core that moves within the coil to change the reactance of the coil, and a diaphragm that moves the core in accordance with changes in received pressure. A base is made of synthetic resin and has a cylindrical part rising from the diaphragm chamber, a lid is attached to cover the diaphragm chamber, a coil is attached to the outer periphery of the cylindrical part, and a cylindrical part rising from the diaphragm chamber is provided. A bearing part is formed in the upper end of the cylindrical part on the opposite side of the diaphragm chamber, and a sliding cylinder which is movably placed inside the cylindrical part is slidably supported on the bearing part. A disc body is formed at the lower end, and this disc body is brought into contact with the back side of the pressure-receiving surface of the diaphragm, and a coil spring is provided to press the disc body toward the diaphragm side, and the core is supported on the sliding cylinder body. A core support cylinder part is provided, and the core support cylinder part is formed in the shape of a disc and a rising cylinder, concentrically with the sliding cylinder body, and the thickness of the core support cylinder part is formed thin, and the core support cylinder part is A core locking pawl facing outward is formed at the upper end of the support tube, and the core, which is provided in the sliding tube and moves within the cylindrical portion of the base, is formed in a cylindrical shape. fitting to the outer periphery and abutting the lower end of the core to the upper surface of the disc body,
Furthermore, a core locking pawl is engaged with the inner edge of the upper end to fix the core to the sliding cylinder, and the lower end of the coil spring is provided between the inner circumference of the core support cylinder and the outer circumference of the sliding cylinder. It is characterized by forming an annular spring storage groove into which the spring is inserted.

[Effect]

By pushing the lower end of the core into the upper end of the core support cylinder provided on the sliding cylinder, the thin core support cylinder is bent inward.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 6.

The base 1 of the displacement detector is made of a rigid body made of ABS resin, polyacetal resin, or the like. An inverted diaphragm chamber 2 is formed in this base 1. A cylindrical portion 3 rising upward from the diaphragm chamber 2 is equipped with a bobbin 4 made of polyacetal resin on its outer periphery. A primary coil 5 and a secondary coil 6 are wound around the bobbin 4,
Both coils 5 and 6 use polyurethane coated wires. A retaining projection 7 is formed on the outer periphery of the upper end of the cylindrical portion 3, and the retaining projection 7 holds the bobbin 4 so that it does not come off from the cylindrical portion 3.

The outer diameter of the winding drum of the bobbin 6 is 17 mm, and the number of turns of both coils 5 and 6 is 2200. Both coils 5, 6
The resistance value is 630-650Ω. The primary coil 5 is arranged on the upper side, and the secondary coil 6 is arranged on the lower side. An electric circuit including both coils 5 and 6 will be described later.

A lid body 8 that covers the diaphragm chamber 2 has a pressure receiving port 9. The tube 10 is connected to the pressure receiving port 9.

Diaphragm 11 that fits within diaphragm chamber 2
are made of rubber or cloth-filled rubber. The outer periphery of the diaphragm 11, which has a flat pressure receiving surface 12, is held between the outer periphery of the diaphragm chamber 2 and the outer periphery of the lid 8. diaphragm 11
The lower surface side is a pressure receiving surface 12, and a base portion 13 is formed at the center of the back surface of this pressure receiving surface 12.

The sliding cylinder 14 has a disc body 15 at its lower end. The sliding cylinder 14 is made of polyacetal resin containing oil or paraffin. Sliding cylinder 1
A threaded portion 16 is provided on the upper side of the hole that passes vertically through the inside of 4.
An adjustment screw 17 is screwed into this threaded portion 16.

The disc body 15 of the sliding body 14 is placed so as to come into contact with the back side of the pressure-receiving surface of the diaphragm 11, and the lower end of the adjusting screw 17 comes into contact with the upper surface of the base portion 13 of the diaphragm 11.

The upper outer periphery of the sliding cylinder 14 is slidably supported by a bearing portion 18 . This bearing portion 18 is formed at the upper end of the cylindrical portion 3.

A core support cylinder portion 19 is formed in the sliding cylinder body 14 . This core support cylinder portion 19 has a cylindrical shape that is concentric with the sliding cylinder body 14 and rises from the upper surface of the disk body 15. This core support cylinder part 19
is formed to have a thin thickness so that it can be easily bent in the inner diameter direction. An outward locking pawl 20 is formed on the outer periphery of the upper end of the core support cylinder portion 19 .

The core 21 supported by the core support cylinder portion 19 has a cylindrical shape. This core 21 is formed using permalloy or a ferromagnetic steel plate. This core 21 is attached so as to fit around the outer periphery of the core support cylinder portion 19. Installation is performed as follows. When the lower end of the core 21 is aligned with the upper end of the core support tube 19 and pushed downward, the core support tube 19 is bent in the inner diameter direction. The core support cylindrical portion 19 is depressed and the core 2
Get inside 1. By pressing the core as it is, the lower end of the core 21 is attached to the disc body 1 of the sliding cylinder 14.
5, and the locking pawl 20 engages with the inner edge of the upper end of the core 21. In this state, core 21
is attached to the core support cylinder portion 19.

An annular spring storage groove 22 is formed between the inner periphery of the core support cylindrical portion 19 and the outer periphery of the sliding cylindrical body 14 . The coil spring 23 attached to the outer periphery of the sliding cylinder 14 is placed so that its upper end is fitted into the outer periphery of the bearing portion 18 and its lower end is fitted into the spring storage groove 22. This coil spring 23 acts to resist the pressure applied to the diaphragm 11.

The protective cover 24 is attached to the bobbin 4 so as to cover both the coils 5 and 6 and the adjustment screw 17.

A vertical rib 26 formed on the inner surface of the cylindrical portion 3 is slidably fitted into the slit 25 of the core 21.

Next, the electric circuit will be explained. As shown in FIG. 5, an oscillation circuit is connected to the primary coil 5 and an amplifier circuit is connected to the secondary coil 6.
A 70KHz square wave is applied. The voltage output from the secondary coil 6 changes because the reactance of the secondary coil 6 changes as the core 21 moves.

Next, the operation will be explained.

From the tube 10 to the pressure receiving surface 1 of the diaphragm 11
When pressure is applied to 2, the sliding cylinder 14 moves upward against the coil spring 23. As the core 21 approaches the secondary coil 6, the voltage induced in the secondary coil 6 changes. FIG. 6 shows the amount of displacement of the core 21 and the change in the induced voltage in the secondary coil 6 due to pressure changes. By reading this induced voltage change, pressure can be detected.

In such pressure detection, it is necessary that the core 21 be securely attached to the sliding cylinder 14. Pressure cannot be detected correctly unless the core 21 is securely attached to the sliding cylinder 14 at a predetermined position. The core 21 is fitted onto the outer periphery of the core support cylinder 19, the lower end of the core 21 contacts the disc body 15, and the upper end is locked by the locking pawl 20, so that it is securely held at a predetermined position on the sliding cylinder 14. Since it is attached to the sensor, it is highly accurate and does not cause pressure detection errors.

Also, since the core 21 moves close to the inner circumference of the cylindrical portion 3 that supports both the coils 5 and 6, the coil 21
The reactance change is large and the detection sensitivity is good.

Further, since the core support cylinder part 19 is formed thin, it is easily bent, and the core 21 can be easily attached to the core support cylinder part 19 by pushing the core 21 into the core support cylinder part 19 . Moreover, the locking claw 20 allows the core 2
1 can be fixed, so there is no need for fixing members such as screws or nuts.

Furthermore, since the core support cylinder portion 19 is formed to be thin, the large diameter of the displacement detector can be reduced accordingly.

In addition, since the thin core support cylinder part 19 becomes strong by fitting the core 21, even if the diaphragm 11 is tilted due to the displacement of the diaphragm 11 due to the pressure received, the spring storage groove 22
The coil spring 23 inserted into the core support tube 19 will not deform and cause malfunction.

〔Effect of the invention〕

As described above, the present invention provides a displacement detector including a coil, a core that moves within the coil to change the reactance of the coil, and a diaphragm that moves the core in accordance with changes in received pressure. A base having a diaphragm chamber in which the diaphragm is housed is formed of synthetic resin, a cylindrical portion rising from the diaphragm chamber is formed on this base, a lid is attached to cover the diaphragm chamber, and a lid body is provided on the outer periphery of the cylindrical portion. The coil is attached, a bearing part is formed at the upper end of the cylindrical part of the base opposite to the diaphragm chamber, and a sliding cylinder is movably placed inside the cylindrical part and is slidably supported by the bearing part. This sliding cylinder has a disc body formed at its lower end, and a coil spring that contacts the back side of the pressure-receiving surface of the diaphragm and presses the disc body toward the diaphragm. The body is provided with a core support cylindrical portion that supports the core, and this core support cylindrical portion is formed in a cylindrical shape that stands up from the disc body and is concentric with the sliding cylinder, and the thickness of the core support cylindrical portion is is formed thinly, and an outward core locking pawl is formed at the upper end of the core support cylindrical part, and the core, which is provided in the sliding cylinder and moves within the cylindrical part of the base, is formed in a cylindrical shape, The core is fitted onto the outer periphery of the core support cylinder, and the lower end of the core is brought into contact with the upper surface of the disc body, and the core is fixed to the sliding cylinder by engaging the core locking claw on the inner edge of the upper end. The present invention is characterized in that an annular spring storage groove into which the lower end of the coil spring is inserted is formed between the inner periphery of the core support cylinder and the outer periphery of the sliding cylinder.

This configuration has the following advantages.

(1) The core is fitted onto the outer periphery of the core support cylinder, and is securely held in a predetermined position by the disc body and the locking pawl without shifting, resulting in good detection accuracy.

(2) Detection sensitivity is good because the core moves close to the inner circumference of the cylindrical part that supports the coil.

(3) Since the core support cylinder part 19 is thin and flexible, the core can be easily attached, and since the core is fixed with a locking pawl, fixing members such as screws and nuts are not required.

(4) Since the flexible core support tube 19 is reinforced by the core, the core support tube 19 will not be deformed by the coil spring inserted into the spring housing groove, thereby preventing malfunction.

[Brief explanation of drawings]

FIG. 1 is a plan view showing one embodiment of the present invention, and FIG.
3 is a front sectional view showing one embodiment of the present invention, FIG. 4 is an exploded perspective view showing one embodiment of the present invention, and FIG. 5 is a drive circuit diagram of one embodiment of the present invention. FIG. 6 is a characteristic diagram of an embodiment of the present invention. 1...Base, 2...Cylindrical part, 5...Differential transformer, 7...Primary side coil, 8...Secondary side coil,
9...Diaphragm, 11...Sliding body, 12...
Disc body, 13...Hollow shaft, 17...Magnetic material, 18
...Pressure adjustment spring, 20 ...Adjustment screw.

Claims (1)

[Claims] 1. A displacement detector comprising a coil, a core that moves within the coil to change the reactance of the coil, and a diaphragm that moves the core in accordance with changes in received pressure, in which the diaphragm is housed. A base having a diaphragm chamber is formed of synthetic resin, a cylindrical portion rising from the diaphragm chamber is formed on the base, and a lid body is provided to be attached to cover the diaphragm chamber,
A coil is attached to the outer periphery of the cylindrical part, a bearing part is formed on the upper end of the cylindrical part of the base on the opposite side of the diaphragm chamber, and a sliding cylinder that is movably placed inside the cylindrical part is slid onto the bearing part. This sliding cylinder is movably supported, and a disk is formed at the lower end of the sliding cylinder, and a coil spring is attached to the disk to abut against the back side of the pressure-receiving surface of the diaphragm and press the disk toward the diaphragm. A core support cylinder part for supporting the core is provided in the sliding cylinder body, and the core support cylinder part is arranged circularly with the sliding cylinder body,
The core support tube is formed in a cylindrical shape rising up from the disk body, and the thickness of the core support tube is made thin, and an outward core locking pawl is formed at the upper end of the core support tube, and the sliding tube is equipped with The core, which is moved within the cylindrical portion of the base, is formed into a cylindrical shape, and is fitted onto the outer periphery of the core supporting cylindrical portion, with the lower end of the core abutting the upper surface of the disk body, and further inside the upper end. An annular shape in which the core is fixed to the sliding cylinder by engaging a core locking pawl on the edge, and the lower end of the coil spring is inserted between the inner periphery of the core support cylinder and the outer periphery of the sliding cylinder. A displacement detector characterized by forming a spring storage groove.