JPH0469325B2 - - Google Patents

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to a pressure detector.

[Background of the invention]

A conventional pressure detector equipped with a conventional differential transformer is shown in Japanese Patent Laid-Open No. 57-60213. The differential transformer of this pressure detector is assembled inside the outer frame, and moreover, at a relatively early stage during assembly. For this reason, when installing a differential transformer, if the wires are connected to the electrode terminals, the wires must be threaded through the transformer, and the installation must be done in a blind manner after the initial positioning of the transformer.

Further, after installation, if a defective part occurs and the part is to be replaced, the differential transformer must be removed from the inside of the outer frame, making disassembly difficult. Particularly, those whose outer frames are welded and fixed so that they are airtight cannot be disassembled, and parts cannot be replaced, and all defective products must be discarded, which is uneconomical.

[Purpose of the invention]

The present invention aims to provide a differential transformer that can be easily installed, maintained, and inspected.

[Summary of the invention]

The present invention includes an outer frame base, a differential transformer, a magnetic body that is moved by displacement of a diaphragm and placed so as to change the distance from the differential transformer, and is formed integrally with the outer frame base. In a pressure sensor equipped with a diaphragm storage section, an outer cover that is attached to cover the opening side of the diaphragm storage section, and a pressure receiving port formed in the outer cover, there is a circle on the back side of the pressure receiving surface of the diaphragm. A plate-shaped slider is provided, and a hollow shaft portion that rises vertically is formed in the center of the slider.
The length of the circumferential wall formed on the slider so as to surround the outer periphery of the hollow shaft is made shorter than the hollow shaft, and the magnetic material is fitted onto the outer periphery of the circumferential wall, and the upper center of the outer frame base is A rising cylindrical part is formed, the inner periphery of this cylindrical part is formed to have a somewhat larger diameter than the outer periphery of the magnetic material so as to guide the movement of the magnetic material, and the hollow shaft part is formed in the upper part of the cylindrical part. A pressure adjustment spring is provided to press the diaphragm toward the pressure receiving port of the outer cover, and the lower end of the pressure adjustment spring is connected to the outer periphery of the hollow shaft part and the inner periphery of the circumferential part. The upper end of the pressure adjustment spring is inserted between The differential transformer has a bobbin, a primary coil and a secondary coil wound around the bobbin, and the inner circumference of the bobbin is fitted to the outer circumference of the cylindrical portion of the outer frame base to perform differential transformation. A retaining protrusion is formed on the upper end of the outer periphery of the cylindrical portion to which the inner periphery of the upper end of the bobbin engages.

[Embodiments of the invention]

An embodiment of the present invention is shown in FIGS. 1, 2, and 3.
This will be explained with reference to FIGS. 4, 5, and 6.

1 is a rigid outer frame base molded from ABS resin or polyacetal resin, with a cylindrical part 2 in the center of the outside.
is provided, and a differential transformer 5 is attached to this cylindrical portion 2.

The differential transformer 5 is formed by winding a primary coil 7 and a secondary coil 8 around a rigid bobbin 6 made of ABS resin, polyacetal resin, or the like.

A retaining protrusion 3 is formed at the upper end of the outer periphery of the cylindrical portion 2 .

By fitting the inner periphery of the bobbin 6 of the differential transformer into the outer periphery of the cylindrical portion 2, the inner periphery of the upper end of the bobbin 6 engages with the retaining protrusion 3, so that the bobbin 6 cannot be easily removed from the cylindrical portion 2. Retained. The bobbin 6 has a winding drum outer diameter of φ17, and is wound 2200 times (resistance value 630 to 650Ω) on both the primary and secondary sides, with the secondary coil 8 located closer to the magnetic material and the primary coil 7 located closer to the outside. Insert fixed, frequency 50~70K into primary coil
A square wave direct current of Hz is applied. Magnetic material 17
is attached so as to slide inside the secondary coil 8.

A diaphragm 9 made of rubber or cloth-filled rubber is placed inside the outer frame base 1. The place where the diaphragm 9 is placed serves as a diaphragm storage section.

The diaphragm 9 has a pressure receiving surface 10 and a platform 19 formed at the center.

The mover 11 placed on the back side of the pressure-receiving surface of the diaphragm 9 includes a disc-shaped disc body 12 and a hollow shaft 13.
and a circumferential wall 14. The mover 11 is made of a rigid body made of polyacetal resin containing oil or paraffin. The hollow shaft 13 is formed to stand up from the center of the disc body 12, and has a thread formed on its upper inner periphery. The circumferential wall 14 is formed to surround the outer periphery of the hollow shaft 13.
The length is sufficiently lower than the length of the A ring-shaped groove 15 is formed on the outer periphery of the hollow shaft 13 and on the inner periphery of the circumferential wall 14.

A bearing portion 4 is formed at the upper end of the cylindrical portion 2 . The upper side of the hollow shaft 13 is slidably supported by the bearing part 4. When pressure is applied to the pressure receiving surface 10 of the diaphragm 9 and the diaphragm 9 bends upward, the mover 11 moves upward. This movement is performed by hollow shaft 1
3 is supported by a bearing part 4. Hollow shaft 1
An adjustment screw 20 is inserted into 3 and screwed into a screw formed on the upper inner periphery of the hollow shaft 13. The adjusting screw 20 is made of polyacetal resin, and its tip abuts against the base 19 of the diaphragm 9. By screwing in the adjustment screw 20, the base portion 19 is pressed more.

A magnetic material 1 is provided on the outer periphery of the circumferential wall portion 14 of the mover 11.
7 is fitted. A retaining protrusion is provided on the outer periphery of the upper end of the circumferential wall portion 14, and this prevents the magnetic body 17 from coming off.

The aforementioned adjustment screw 20 is for adjusting the positional relationship between the magnetic body 17 and the secondary coil 8.

The magnetic body 17 is formed using permalloy or a ferromagnetic steel plate. The circular magnetic body 17 has a groove 25 , and a guide projection 26 that guides the groove 25 is formed on the inner circumference of the cylindrical portion 2 .

The mover 11 is guided by the groove 25 of the magnetic body 17 and the guide protrusion 26 to slide vertically without rotation in the circumferential direction.

The steel wire pressure adjustment spring 18 presses the mover 11 against the upward force of the diaphragm 9. The lower end of the pressure adjustment spring 18 is pushed into the circumferential groove 15 of the slider 11. the spring 18
The upper end of is in contact with the upper outer periphery of the bearing portion 4 of the cylindrical portion 2 .

When pressure is applied to the diaphragm 9, the magnetic body 17
The movable body 11 moves upward so that the magnetic body 11 approaches the secondary coil 8, and as the pressure on the diaphragm 9 decreases, the movable body 11 moves downward so that the magnetic body 17 moves away from the secondary coil 8.

Since the inner circumferential surface of the cylindrical portion 2 and the outer circumference of the magnetic body 17 are adapted to slide, they constitute a guide portion when the movable body 11 moves up and down.

The outer lid 21 closes the opening side of the diaphragm storage section. This outer lid 21 is rigid and made of ABS resin or polyacetal resin.

The outer cover 21 is welded and fixed to the outer frame base 1.
An air chamber 29 is provided between the outer lid 21 and the diaphragm 9. At the center of the outer lid 21, there is a pressure receiving port 22 to which a pressure transmitting tube 24 led from a washing tub of a washing machine or the like is connected. A deflection prevention protrusion 23 is formed around the inner outlet of the pressure receiving port 22.

The protective frame 27 covers the differential transformer 5. This is for dustproofing and waterproofing the differential transformer 5.
The claws 28 of the protective frame 27 engage with the end edges of the bobbin 6 of the differential transformer 5 to prevent the protective frame 27 from coming off.

Next, the operation will be explained.

When the primary coil 7 of the differential transformer 5 has the drive circuit shown in FIG. 5 and a 5V square wave DC power source is applied at a frequency of 50 to 70KHz, an initial induced voltage of 0.2V is generated in the secondary coil 8. That's about it. When air is forced into the pressure receiving port 22, the pressure receiving surface 1 of the diaphragm 9
0 floats up and resists the pressure adjustment spring 18 to the disk body 1
Press up each side of 1 evenly. Therefore, the magnetic body 17
The output side, that is, the secondary side coil 8 is slid while maintaining a uniform gap with the inner peripheral part of the differential transformer 5 without being oblique. When the magnetic body 17 slides, it directly acts on the lines of magnetic force generated in the secondary coil 8.
As shown in the figure, the output voltage (thick line) is greater than the output voltage (thin line) when sliding inside the primary coil 7.
becomes.

The pressure adjustment spring 18 expands and contracts within the differential transformer 5, and when it bends, it increases the density of the steel wire, increases the density of the lines of magnetic force, and the magnetic body 1 as shown by the broken line in FIG.
7 outputs a voltage that is gradually added to the output voltage (thick line) alone, and when the magnetic body 17 moves to the position (approximately 4 mm) as shown in Figure 3, the induced voltage becomes 4.5V.
It will be about. In other words, when the magnetic body 17 moves 4 mm, the voltage change amount is 4.5V, which is a large value, and the fifth
It is easy to perform the discrimination process using the circuit shown in the figure.

〔Effect of the invention〕

As described above, the present invention includes an outer frame base, a differential transformer, a magnetic body that moves according to the displacement of a diaphragm and is placed so that the distance from the differential transformer changes, and an outer frame base that is integrated with the outer frame base. A pressure detector comprising a diaphragm storage section formed in the diaphragm storage section, an outer cover attached to cover the opening side of the diaphragm storage section, and a pressure receiving port formed in the outer cover,
A disk-shaped slider is provided on the back side of the pressure-receiving surface of the diaphragm, a hollow shaft is formed vertically in the center of the slider, and the slider is formed so as to surround the outer periphery of the hollow shaft. The length of the circumferential wall portion is made shorter than the hollow shaft portion, the magnetic material is fitted onto the outer periphery of the circumferential wall portion, a rising cylindrical portion is formed at the upper center of the outer frame base, and the height of the cylindrical portion is The inner periphery is formed to have a somewhat larger diameter than the outer periphery of the magnetic material so that it can guide the movement of the magnetic material.
A bearing part that slidably supports the hollow shaft part is formed in the upper part of the cylindrical part, and a pressure adjustment spring that presses the diaphragm toward the pressure receiving port of the outer cover is provided, and the lower end of the pressure adjustment spring is attached to the hollow shaft part. The upper end of the pressure adjustment spring is pressed against the outside of the bearing of the hollow shaft, and the tip of the adjustment screw inserted from the upper end of the hollow shaft is inserted into the diaphragm. The differential transformer is in contact with the center of the back surface of the pressure receiving surface, and has a bobbin, a primary coil and a secondary coil wound around the bobbin, and the inner periphery of the bobbin is connected to the cylindrical portion of the outer frame base. The pressure detector is characterized in that a differential transformer is attached to the cylindrical part by fitting the outer periphery of the cylindrical part, and a retaining protrusion is formed on the upper end of the outer periphery of the cylindrical part, with which the inner periphery of the upper end of the bobbin engages.

The above configuration has the following advantages.

(1) Provide a cylindrical part rising from the center of the outer frame base,
The differential transformer is made up of a bobbin, a primary coil and a secondary coil wound around the bobbin, and the inner circumference of the bobbin is fitted into a cylindrical part, so the diaphragm, moving body, pressure adjustment spring, and adjustment After the screws are assembled, the differential transformer can be installed. Installation of the differential transformer is easy.

(2) A retaining protrusion is formed on the upper end of the outer periphery of the cylindrical part, and the inner peripheral edge of the upper end of the bobbin fitted into the cylindrical part engages with the retaining protrusion, so that the differential transformer can be easily removed from the cylindrical part. It will never come off.

(3) Since the differential transformer can be removed without removing other parts including the slider, maintenance and inspection can be easily performed by removing only the differential transformer from the cylindrical part.

(4) A steel wire pressure adjustment spring is placed on the inner periphery of the magnetic body that moves toward or away from the secondary coil, so the compression of this steel wire pressure adjustment spring assists the action of the magnetic body. Therefore, the detection sensitivity of pressure change is good.

[Brief explanation of the drawing]

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, and FIG. 7 is a front sectional view showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Outer frame base, 2... Cylindrical part, 5... Differential transformer, 7... Primary coil, 8... Secondary coil, 9... Diaphragm, 11... Mover, 12
... Disk body, 13 ... Hollow shaft, 17 ... Magnetic material,
18...Pressure adjustment spring, 20...Adjustment screw.

Claims (1)

[Scope of Claims] 1. An outer frame base, a differential transformer, a magnetic body that moves according to the displacement of a diaphragm and is placed so that the distance from the differential transformer changes, and an outer frame base integrally formed with the outer frame base. In a pressure sensor equipped with a diaphragm storage section, an outer cover that is attached to cover the opening side of the diaphragm storage section, and a pressure receiving port formed in the outer cover, the rear side of the pressure receiving surface of the diaphragm is is provided with a disk-shaped slider, a hollow shaft portion rising vertically from the center of the slider is formed, and a circumferential wall portion formed on the slider to surround the outer periphery of the hollow shaft portion has a hollow length. The magnetic material is fitted onto the outer periphery of the circumferential wall, and a rising cylindrical portion is formed at the upper center of the outer frame base, and the inner periphery of the cylindrical portion is formed so that the magnetic material is lower than the shaft. a diameter somewhat larger than the outer periphery of the magnetic body so as to guide the magnetic body, a bearing part for slidably supporting the hollow shaft part is formed in the upper part of the cylindrical part, and a diaphragm is connected to the pressure receiving port of the outer cover. A pressure adjustment spring made of a steel wire that presses toward The tip of the adjustment screw inserted from the upper end of the hollow shaft part is pressed against the outside of the hollow shaft part, and the tip of the adjustment screw is brought into contact with the center of the back surface of the pressure receiving surface of the diaphragm. and a secondary coil, the inner periphery of the bobbin is fitted to the outer periphery of the cylindrical part of the outer frame base to attach the differential transformer, and the upper inner periphery of the bobbin is on the upper end of the outer periphery of the cylindrical part. A pressure detector characterized by forming an engaging retaining protrusion.