JPS6142066Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention mainly relates to a frost sensor that detects the adhesion of frost on the cooling section of refrigeration equipment or refrigeration equipment.

Generally, frost adheres to heat exchangers such as cooling devices and heat pumps, and as this frost adheres, heat exchange efficiency decreases, resulting in a decrease in cooling efficiency. For this reason, it is necessary to remove the frost that has adhered at an appropriate time, but this has been done by periodically energizing the defrosting heater using a timer without detecting the frost at all.

In this case, the defrost heater may operate even when there is almost no frost, consuming electricity wastefully, or the defrost heater may not operate until a certain period of time even when there is a lot of frost, causing the cooling. If the efficiency continued to decrease, many inconveniences would occur.

For this reason, the frost adhesion can be detected and
A frost sensor that operates a defrosting heater depending on the state of frost adhesion has been developed and is now in use.

A conventional frost sensor of this type was constructed as shown in FIG.

That is, a case made of metal with an open bottom and a ring-shaped recess 1 provided at the peripheral edge of the ceiling surface, a portion surrounded by this recess 1 serving as a diaphragm 2, and a flange 4 provided on the outer periphery of the lower end of a cylindrical portion 3. A piezoelectric element 6 is bonded to the inner surface of the diaphragm 2 of No. 5, and an isolation disk 7 made of an insulating material such as synthetic resin or rubber is incorporated inside the case 5. A holding piece 8 that protrudes is provided, a heater 9 is held on this holding piece 8, lead wires 10 and 11 are connected to this heater 9 and piezoelectric element 6, and this lead wire 1
An insulating sheet 12 is placed on the heater 9 in order to insulate the connecting portions 0 and 11, and an insulating sheet 12 is placed on the heater 9 below the isolating disk 7 of the case 5 to prevent cracks. The resin 13 is filled with a resin 13 such as a flexible epoxy resin containing a filler having high thermal conductivity so as to conduct the heat to the case 5.

With this configuration, the piezoelectric element 6 is connected to an external oscillation circuit by a lead wire 10 and self-oscillates, and when frost adheres to the surface of the diaphragm 2, the resonance impedance increases and the oscillation level changes. Detecting this change, the defrosting heater is activated and the heater 9
Electricity is applied to the diaphragm 2 to heat the diaphragm 2, defrost it, and return it to its original detection state.

In the conventional frost sensor as described above, heat from the heater 9 cannot be efficiently transmitted to the diaphragm 2 due to large heat diffusion from the surface of the resin 13, and the heater 9 must be operated for a long time. There was a flaw that I thought it should be.

The purpose of the present invention is to eliminate the above-mentioned drawbacks of the conventional technology and provide a frost sensor that can efficiently conduct the heat of the heater to the diaphragm and defrost the surface of the diaphragm reliably in a short period of time. It is something.

That is, the frost sensor of the present invention is constructed as shown in FIGS. 2 and 3. A case 18 made of metal is provided with a ring-shaped recess 14 at the peripheral edge of the ceiling surface with an open bottom, a part surrounded by this recess 14 has a frequency of 15, and a flange 17 is provided on the outer periphery of the lower end of the cylindrical part 16. In preparation, the diaphragm 15 of this case 18
A piezoelectric element 19 is bonded to the inner surface of the case 18, and an isolation disk 20 made of synthetic resin, rubber, etc. is housed in the middle part of the interior of the case 18, and a holding piece is provided on the lower surface of the isolation disk 20 to protrude downward. 21 is provided, and this holding piece 21 holds a heater 22.

A lead wire 23 is connected to the piezoelectric element 19 and connected to an external oscillation circuit, and a lead wire 24 is connected to the heater 22.

Note that an insulating sheet 25 made of mica or the like is arranged between the heater 22 and the isolation disk 20 to insulate the connecting portion of the lead wires 23 and 24.

Further, below the isolation disk 20 of the case 18, a flexible epoxy material with low hardness to prevent cracks due to thermal shock and a filler with high thermal conductivity is used to efficiently conduct heat from the heater 22 to the case 18. A resin 26 such as resin is filled.

Further, on the lower surface of the resin 26, a fixing plate 27 made of glass epoxy resin or the like having lower thermal conductivity and greater hardness than the resin 16 is provided. A semicircular notch 2 is formed in a part of the peripheral edge of this fixing plate 27.
8 is formed, and the lead wire 2 is inserted from this notch 28.
3 and 24 are drawn out. Note that a heat shrink tube 29 is placed over the lead wires 22 and 23 passing through the notch 28.

Further, the fixing plate 27 can be fixed by holding the lower part of the case 18, or can be fixed by simply bonding to the resin 26.

As the frost sensor of the present invention is configured as described above, even if the heat from the heater attempts to dissipate from the surface side of the resin, it is insulated by the fixed plate and is ultimately conducted to the case, causing heat to adhere to the diaphragm. In addition to effectively removing frost, even if an external force is applied to the lead wire, the fixing plate disperses the external force, so it does not affect parts such as solder connections, and the tensile strength of the lead wire is improved. It is possible to obtain effects such as improvement in reliability and reliability.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional frost sensor, FIG. 2 is a sectional view of the frost sensor of the present invention, and FIG. 3 is a top view of a fixing plate used in the sensor. 14... recess, 15... diaphragm, 16... cylindrical part, 17... collar, 18... case, 19... piezoelectric element, 20... isolation disk, 21... holding piece, 22
... Heater, 23, 24 ... Lead wire, 25 ...
Insulating sheet, 26...Resin, 27...Fixing plate, 2
8...Notch, 29...Heat shrink tube.

Claims (1)

[Scope of utility model registration request] A case made of metal is provided with a diaphragm integrally provided on the top surface, a piezoelectric element is coupled to the inner surface of the diaphragm of this case, and an isolating disk holding a heater on the bottom surface is arranged inside the case. In a frost sensor in which a lead wire is connected to a piezoelectric element and a heater, and a resin with low hardness and high thermal conductivity is filled in the case below the isolation disk, the lower surface of the resin filled in the case has a high thermal conductivity. A frost sensor equipped with a low and hard fixed plate.