JPS6145454Y2 - - Google Patents

Description

[Detailed description of the invention] This invention uses a vibrator in which a piezoelectric ceramic plate is bonded to a metal diaphragm, and utilizes the mechanical resonance of the metal diaphragm and the piezoelectric effect of the piezoelectric ceramic plate, and changes in the resonance resistance. The present invention relates to a level detector that detects the level of an object to be detected, such as liquid, powder, or granules in a container, and attempts to provide a level detector that is stable and has high detection accuracy with little variation in resonance resistance.

In conventional level detectors, the periphery of a vibrator 5 made of a metal diaphragm 4 made of a metal diaphragm 4 with a piezoelectric ceramic plate 3 affixed to the inner surface of a step 2 on the upper end surface of a case 1 made of metal or synthetic resin is made of silicone rubber or the like. It is attached using an elastic adhesive 6, and a terminal plate 8 on which a plurality of terminals 7 are implanted is coupled to the lower surface of the case 1, and the terminals 7 are connected to the electrodes of the piezoelectric ceramic plate 3 by lead wires 9.

As shown in FIG. 2, this configuration is used when it is installed in the opening 12 on the side or bottom of the container 11 that stores the substance 10 to be detected, and it is used to check the remaining level of the substance 10 in the container 11. It is detected by a change in the resonant resistance of the vibrator 5.

However, in the level detector described above, the metal diaphragm 4 of the vibrator 5 is placed on the elastic adhesive 6, and then the elastic adhesive 6 is cured to elastically couple the vibrator 5 to the case 1. If the viscosity of the elastic adhesive 6 is low, the vibrator 5 may sink and tilt due to its own weight.
On the other hand, if the viscosity is high, it will be difficult to apply it uniformly to the stepped portion 2 of the case 1, and the adhesive will partially protrude near the center of the metal diaphragm 4 and harden, suppressing vibration in this area and causing resonance. The resistance increases or the vibration state changes, causing harmonic oscillation.
Detection accuracy may decrease or become unstable. Furthermore, if the transducer 5 is tilted or sunken, the height of the outer periphery of the case 1 and the height of the transducer 5 will be different, and the substance 10 to be detected will remain on the transducer 5, creating a large resonance resistance. This method has a disadvantage in that even if the overall level of the detection substance 10 has decreased, a false detection may be made as if a large amount of the substance 10 to be detected is present.

The present invention eliminates the above-mentioned drawbacks of the prior art.

Hereinafter, an embodiment of the present invention will be explained with reference to FIG. 3 of the drawing.

Reference numeral 12 denotes a case made of metal or synthetic resin, and a step 13 is formed at the upper part of the case 12, and this step 13 has a projection 14 with a sharp tip.
There are several.

The peripheral edge of the vibrator 15 is positioned on the step 13 by the protrusion 14, and the step 13
3 is elastically bonded with a silicone rubber-based elastic adhesive 16 applied thereto. The vibrator 15 is constructed by pasting a piezoelectric ceramic plate 18 on the lower surface of a metal diaphragm 17, and the support portion of the vibrator 15 by the protrusion 14 serves as a node when the vibrator 15 vibrates. This makes it possible to reduce an increase in the resonance resistance of the case 5 and vibration leakage to the case 12.

Further, a terminal plate 20 having a plurality of terminals 19 embedded therein is incorporated in the lower surface of the case 12, and a lead wire 21 drawn out from an electrode of the piezoelectric ceramic plate 18 of the vibrator 15 is connected to this terminal 19. .

With this configuration, the usage condition is the same as that shown in FIG.

As described above, the level detector of the present invention supports the vibrator by the protrusion provided on the step of the case, and then
Because they are elastically bonded using elastic adhesive, the relative position of the transducer and case is stable, and the transducer does not tilt or sink relative to the case, and the substance to be detected remains on the transducer. There is nothing to do,
The elastic adhesive does not spill out and adhere to the transducer, allowing the transducer to operate correctly and perform accurate level detection, making it highly reliable and of practical value. It is a big thing.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a conventional level detector, Fig. 2 is a sectional view showing how the same level detector is used,
FIG. 3 is a sectional view showing an embodiment of the level detector of the present invention. 12...Case, 13...Step part, 14...Protrusion, 15
... vibrator, 16 ... elastic adhesive, 17 ... metal diaphragm, 18 ... piezoelectric ceramic plate, 19 ... terminal, 20 ... terminal plate, 21 ... lead wire.

Claims (1)

[Scope of utility model registration request] A level detector is constructed by elastically bonding the peripheral edge of a vibrator, which is constructed by attaching a piezoelectric ceramic plate to the bottom surface of a metal diaphragm to the bottom surface of a metal diaphragm, to the step at the upper end of the case. A level detector in which a plurality of protrusions are provided on the section, the upper ends of the protrusions support the peripheral edge of the vibrator, and are elastically connected using an elastic adhesive.