JPS61132825A - Manufacture of piezoelectric type liquid level sensor and piezoelectric type liquid level sensor - Google Patents

Abstract

PURPOSE:To prevent a weight of a lead from being applied to a piezoelectric element, and also to execute easily an assembly by joining an insulating plate to the upper end face of a base, joining a terminal formed plate onto its insulating plate, and cutting and removing a holding ring of its outside periphery. CONSTITUTION:A piezoelectric element 2 having an excitation electrode 3a, a feedback electrode 3b and a common electrode is joined to the center part of the inner surface of a cap 1 which has been formed in a shape of a bowl. Also, a base 5 is stuck to the cap 1, and an insulating plate 8 is joined to the upper end face of the base 5. Subsequently, a terminal formed plate 16 is joined onto its insulating plate 8, and thereafter, by cutting and removing a holding ring 17 of its outside periphery, only terminals 18-20 are left on metallized parts 9-11.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for manufacturing a piezoelectric level sensor and a piezoelectric liquid level sensor, and relates to a method for manufacturing a piezoelectric level sensor and a piezoelectric liquid level sensor. To check whether the vibration element is below the liquid level or not, immerse it in the liquid or apply a voltage to the piezoelectric element of the vibrating element that becomes relatively above the liquid level as the liquid decreases. The field of application is a method for manufacturing a level sensor that detects whether a signal voltage can be extracted depending on whether it is above a surface, and the level sensor itself.

(Prior Art) A piezoelectric liquid level sensor has been known for a long time, and as shown in FIG.
A vibrating plate f having an excitation vibration [1iC and a return electrode d on the surface and a piezoelectric element having a common electrode e on the back side attached to the inner surface using the same #I configuration as the piezoelectric element shown in Fig. 12 is oil-tight. Connect the cable h to the gasket 9 attached to the upper end of the body pipe a, and connect the lead 1MI exposed from the cable.
L1. J, are connected to the excitation electrode C, the return electrode d, and the body tube a, respectively.

(Problems to be Solved by the Invention) In the above-described known piezoelectric liquid level sensor, the lead wires 5 to K are connected to each other, and then each lead wire is passed through the interior of the metal body tube a to connect to the vibrating plate C. The assembly cannot be completed unless the body tube & is joined and then the gasket 9 is fitted into the upper end opening of the body tube a.
In order to absorb vibration, each lead wire must be loosened within the body tube a. However, since the lead wire exposed near the packing is long and heavy, most of its total weight is placed on the piezoelectric element. , interrupting the vibration of the vibrating element consisting of the vibrating plate f and the piezoelectric element when voltage is applied;
Or, there is a deficiency α such as adding noise to the detection signal from lead #Ij.

(Means for Solving the Interval M Problem) The invention of tJ & 1 of the present invention does not apply the weight of the lead wire to the vibration #l element, and also facilitates assembly, and has an excitation electrode and a feedback l1li pole on the surface. A piezoelectric element having a common electrode on the back surface is attached to the center of a large-diameter vibrating plate made of a cap with the common electrode in contact with the cap.
It is attached to the lower end of a ring-shaped base whose inner diameter is larger than that of the pressure element and whose upper end is cut in diameter. A terminal forming plate was provided with three terminals protruding from the inner periphery of the diameter retaining ring at different angles, each terminal of the M molded plate was glued to an insulating plate, the retaining ring was cut off, and two more terminals were attached. Terminals are connected to the excitation electrode and return electrode separately, and insulated lead wires are connected to these terminals separately, and the lead wires or a total number of lead wires including the lead wires are passed through the upper end. The gist of the invention is to join the lower end of the metal body tube protruding from the base to the base by welding or the like.

In addition, the invention of tI42 of the present invention has a configuration in which the lead wire is not hung vertically on the vibration #J element, and a piezoelectric element having an excitation electrode and a return electrode on the front surface and a common electrode on the back surface is made of a cap. A common electrode is attached in contact with the center of a large-diameter vibrating plate, and the cap is oil-tightly attached to the lower end of a ring-shaped base whose inner diameter is larger than that of the piezoelectric element and whose upper end is cut in diameter. A ring-shaped insulating plate is glued to the reduced diameter end face of the base, three terminals are attached to the insulating plate at different angles, and two of the terminals are attached to the excitation electrode and the return electrode, respectively. Connect the insulated lead wires to these terminals separately, pass the lead wires inside, and connect the lower end of the metal body tube protruding from the upper layer to the above one by welding or the like. The gist of the invention is that the terminal is a ground terminal connected to the base, and this is joined to the inner surface of the metal body tube, and the first invention is utilized.

(Function) The first invention of the present invention is a piezoelectric element and a vibrating plate (cap).
Do not attach elements consisting of directly to a metal body (,
It is attached to the lower end of a ring-shaped base whose inner diameter is larger than the outer diameter of the piezoelectric element, a ring-shaped insulating plate is attached to the upper end of the base, and a retaining ring is used to glue three terminals onto the insulating plate. This method uses a terminal forming plate in which three terminals are formed at different angles from the inner circumference, and the forming plate can be formed by pressing means, so when multiple terminals are individually bonded to an insulating plate. Compared to the above, it is easier to determine the bonding position, resulting in significant labor savings. In addition, since the holding ring of the terminal forming plate is separated after each terminal is glued, each terminal can be made electrically independent, preventing short circuits, and two of the three terminals mentioned above can be separated. The terminal is the excitation electrode of the piezoelectric element! ! It is connected to the electrode through a sheathed ring wire, etc., and the ring-shaped base that supports the insulating plate on the upper end surface can be of low height, so the lead wires etc. mentioned above can be short, and the weight is reduced compared to the piezoelectric Since it does not cover the piezoelectric element, it can be manufactured with a configuration in which the vibration of the vibrating element is not disturbed when voltage is applied to the piezoelectric element. In addition to the lead wires connected to the terminals, the metal body tube protrudes from the upper end by loosely inserting the lead wires into the center hole and holding the lead wires connected to one pole, such as the e-pole of the power supply, if necessary. The lower end is fitted onto the outer periphery of the insulating plate and attached to the ring-shaped base by caulking, welding, or soldering. It can prevent intrusion into the interior, does not add weight to the piezoelectric element, makes it easy to install three pieces, and if necessary, the level sensor with a ground connection attached to the metal body can be installed with a level sensor that does not look like the conventional one. It can be manufactured into shapes with no major differences.

The second invention of the present invention is #! As described in the invention of No. 1, in addition to the structure in which the weight of the ring wire is not applied to the piezoelectric element of the vibrating element, the number of ring wires can be reduced because the metal body is made of 7-slices.

(Example) Embodiments of the invention will be described with reference to the accompanying drawings.

In the figure, (1) is a dish-shaped cap, with an excitation electrode (3a) and a return electrode (3b) at the center of its inner surface.
) and has a large current on the back! (4) A piezoelectric element (
2), the common electrode (4) is joined and attached. The cap (1) uses a cap with a larger diameter than the piezoelectric element (2).The cap (5) has an inner diameter larger than the outer diameter of the piezoelectric element [2], and a side diameter step on the upper side. A ring-shaped base formed with a surface (6) and a side diameter 4i1ii (7), and the peripheral edge of the cap (1) is oil-tightly adhered to a shallow annular groove formed on the lower end surface of the base (5). . Also base (5)
A small insulating plate (8) made of alumina porcelain is pasted on the side diameter end face (7) of the metallized (
9), Do), m) are applied at equal angles, and metallization (1
A pore (12) with metallization (lla) on the peripheral wall is formed in the center of 1), and the base (5) and metallization (11) are formed.
and are electrically connected through metallization (l1m).

(16) has three terminals (18), (19), (2
0) is integrally molded with a protruding terminal, each terminal (18) to (20) is formed into a T-shape, and a retaining ring (17)
The inner end portions of the terminals (18) to (20) are aligned with the metallization (9), (10), and (11), respectively, and bonded with small particles of solder.

After bonding, the retaining ring (17) is removed by cutting it from the area marked with an X in FIG. 2, and a shaped terminal piece is made to protrude from each terminal.

The terminals (18) and (19) are connected to the excitation electrode (3a) and the return electrode (3b) of the piezoelectric element (2) separately by thin gold A wires, and the terminals (18) and (19) are connected separately to the excitation electrode (3a) and the return electrode (3b) of the piezoelectric element (2). A common insulating coating (21) is applied to the protrusion ff6, and the cable-like lead wires (22) and (23) are connected separately.

(24) is attached to the side diameter step 1iii (6) of the base (5) at the lower end.
), which has an insulating coating (21) through which the leads (22) and (23) are passed through and protrudes upward; Place the remaining terminals (20) with the protruding parts bent, and then attach the terminals (20).

-1<24) is passed around the outer periphery of the Ja green plate (8), and its lower end surface is joined to the side diameter stepped surface (6) of the base (5), and joined in an oil-tight manner using welding means, brazing, etc. . This body! (24)
At the same time as the terminal (20) is passed through, the tip portion of the terminal (20) comes into contact with the inner surface of the body tube (24). That is, the body tube (24) becomes the 7th pole of the common pole (4) of the piezoelectric element (2).

After the metal body pipes (24) are joined as shown in Mi, the insulation coating (21) is tensioned and the hollow pipe (24) is caulked (25) to fix it.

The lead wire (22) serves as a conducting wire for applying voltage to the piezoelectric element (2), and the lead wire (Z3) serves to take out a signal current generated by the vibration of the vibrating element consisting of the piezoelectric element (2) and the cap (1). .

(Effect of the invention) The invention of tl & 1 of the present invention is such that an insulating plate (8) is joined to the upper end surface of the base (5), and a terminal (1) is placed on the 48 m plate (8).
The terminal forming plate (16) is used to join 8) to (20), and after joining, the retaining ring (1
7) includes the step of cutting and removing the piezoelectric element (2).
Regardless of whether a large number of terminals (18) to (20) are used, manufacturing is possible without adding the weight of the lead wires (22) and (23) to the lead wires, and without affecting the vibration of the lead wires themselves. make it easier.

The second invention of the present invention uses the first invention to ground the metal body (24), thereby reducing the use and wastage of lead wires such as (22) and (23), and moreover, it is completely functional. This has the effect of configuring a piezoelectric liquid level sensor without any problems.

[Brief explanation of drawings]

1 to 4 show examples of the present invention, FIG. 11 is a partially cutaway front view of the product, FIG. 2 is a partially cutaway perspective view, and FIG. FIG. 4 is an enlarged side view cut along the line A-A, and FIG. 4 is an enlarged front view of the main parts. FIG. 5 is a longitudinal sectional front view of a conventional piezoelectric liquid level sensor. (1) → Cap (2) → Piezoelectric element (5) → Base (8) → Insulating plate (17) → Retaining ring (18), (19), (20) → Terminal (22), (23) - Lead Line (24) - Application filed for metal body tube NGK Spark Plug Co., Ltd. Figure 2

Claims (2)

[Claims] (1) A piezoelectric element having an excitation electrode and a return electrode on the front surface and a common electrode on the back surface is attached to the center of a large-diameter vibrating plate consisting of a cap with the common electrode in contact with the inner diameter of the cap. It is attached to the lower end of a ring-shaped base that is larger than the piezoelectric element and has a diameter reduced toward the upper end, and a ring-shaped insulating plate is glued to the reduced diameter end face of the base. A terminal forming plate with three terminals protruding from the inner circumference at different angles is provided, each terminal of the forming plate is adhered to an insulating plate, the retaining ring is separated, and two terminals are attached to the excitation electrode. and a return electrode, and insulated lead wires are connected to these terminals separately, and the lead wires or the required number of lead wires including the lead wires are passed inside and protruded from the upper end. A method for manufacturing a piezoelectric liquid level sensor, characterized in that the lower end of the tube is joined to the base by welding or the like. (2) A piezoelectric element having an excitation electrode and a return electrode on the front surface and a common electrode on the back surface is attached to the center of a large-diameter vibrating plate consisting of a cap with the common electrode in contact, and the inner diameter of the cap is It is oil-tightly attached to the lower end of a ring-shaped base that is larger than the piezoelectric element and has a diameter cut at the top end, and a ring-shaped insulating plate is glued to the cut-diameter end surface of the base. Attach the terminals at different angles, connect two of the terminals to the excitation electrode and the return electrode separately, and connect insulated lead wires to these terminals separately,
Pass the lead wire inside the metal body tube and connect the lower end of the metal body tube protruding from the upper end to the base by welding or the like, and use the remaining terminal as a ground terminal connected to the base. A piezoelectric liquid level sensor characterized by being bonded to.