JPH0468548B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a detection switch that detects abnormally high pressure and overfilling of refrigerant filled in a system of a cooling device.

In conventional cooling systems, abnormally high pressure of the sealed refrigerant occurs due to insufficient capacity of the condenser, clogging of the condenser, or failure of the fan motor.

For this reason, a pressure switch is used, but conventional pressure switches could detect abnormally high pressure of the refrigerant but could not detect overfilling of the refrigerant.

The present invention has been invented in view of the above points, and according to the present invention, it is possible to provide a detection switch capable of detecting abnormally high pressure of refrigerant filled in a system of a cooling device and overfilling of refrigerant.

That is, the present invention includes a pipe through which high-pressure system liquid refrigerant discharged from a compressor passes, a sensing part in which a temperature-sensing part at the end is exposed and only the same refrigerant as the system liquid refrigerant is sealed in the pipe, A snap disc is fixed to the sensing part and has one side exposed to high-pressure liquid refrigerant and the other side exposed to the refrigerant on the sensing part side, and a snap disk is provided in the tube so as to airtightly surround the sensing part. A switch body, a fixed contact supported by the switch body,
The movable contact is actuated by reversing the snap disk and is also supported by the switch body,
The refrigerant in the sensing part is heated to a predetermined temperature by the compressor, and the refrigerant is sealed in the sensing part so that a pressure-temperature characteristic curve is obtained in which the temperature rises but the pressure hardly rises. This is a characteristic feature.

Furthermore, according to the present invention, since the refrigerant in the sensing part is sealed as described above, the temperature and pressure change along the normal saturation curve where liquid and gas coexist until the predetermined temperature is reached. When the temperature is reached, everything becomes gaseous, and a characteristic curve is drawn in which the pressure hardly increases even if the temperature rises further.

In addition, when the refrigerant in the system of the cooling device is overfilled, the value of the degree of subcooling at a certain pressure increases, and the predetermined pressure difference of the refrigerant between the system and the sensing part on both sides of the snap disc increases. When the temperature reaches the predetermined temperature, the on/off operation curve, which connects the operating points at which the snap disc reverses itself to open and close the switch, also draws a curve along the characteristic curve.

Furthermore, since the temperature and pressure of the refrigerant charged in the system change along a saturation curve where liquid and gas coexist, this saturation curve may intersect with the off-operation curve at a certain pressure. This intersection point is the detection point for abnormally high pressure of the refrigerant filled in the system, and from the above, the detection switch according to the present invention can detect abnormally high pressure and overfilling of the refrigerant filled in the system of the cooling device. .

An embodiment of the present invention shown in the drawings will be described below. Reference numeral 1 denotes a pipe through which high-pressure system liquid refrigerant discharged from a compressor passes, and the lower part of a cylindrical switch main body 3 whose top and bottom are open is fixed to this pipe through an opening 2 in a liquid-tight manner. A bowl-shaped sensing portion 4 is housed within the switch body 3 and is supported by engaging a lower circumferential surface 6 of an upper stopper 5 with a stepped portion 7 of the switch body 3. 8 indicates a hole provided in the center of the stopper 5.

A tubular temperature sensing section 9 is attached below the sensing section 4 in a fluid-tight manner so as to communicate with the inside of the sensing section.

A lid 10 is provided on the top of the switch body 3. The upper edge 11 of the switch body 3 is appropriately welded to the lid 10 to fix the lid 10 to the switch body 3.

Terminals 12 and 13 are attached to the lid 10 via appropriate hermetic seals 14 and 15,
A switch lever 16 is attached to the lower end of one terminal 12.
One end is fixed, and a movable contact 17 is provided at the other end.

A disk-shaped snap disk 18 is attached to the upper surface of the stopper 5 so that its peripheral edge is airtight with respect to the stopper. An insulator 1 is provided between the switch lever 16 and the snap disk 18.
9 is provided.

One end of the terminal 13 is connected to one side of an electric load 20 such as a relay, and the other end has a fixed contact 21 facing the movable contact 17. The other electrical load is connected to terminal 12.

However, small gaps 22, 2 are formed between the stopper 5, the switch body 3, and the lid 10 by appropriate means.
3 and 24. There are also gaps 25 and 26 between the sensing section 4, the temperature sensing section 9, and the switch body 3, respectively, which communicate with the small gaps.

Thus, FIG. 1 shows the main switch in a closed state, and FIG. 2 shows the main switch in an open state.

Therefore, the refrigerant is filled into the system of the cooling device so that the liquid and gas always coexist, no matter what the pressure and temperature are.

In this case, the pressure-temperature characteristic curve of the refrigerant becomes a curve abc as shown in FIG. 3, where the horizontal axis is the temperature and the vertical axis is the pressure.

Also, if the refrigerant in the sensing part 4 is filled so that it becomes completely gaseous at a predetermined temperature (approximately 72°C in Figure 3), the characteristic curve at this time will be as shown in a-b-d. In other words, between curves b and d, the pressure hardly increases even if the temperature increases.
Naturally, it is necessary that the refrigerant filled in the system and the sensing section be the same refrigerant, such as R-12.

It is well known that when the temperature of a refrigerant at a certain pressure is lower than the saturation temperature at that pressure, it is called a supercooled state, and the difference from the saturation temperature is the degree of supercooling. The off-actuation curve connecting the points at which the contacts turn off due to the actuation of the snap disk is represented by a'-b'-d'. Conversely, an on-actuation curve connecting points at which the contact is turned on by actuation of the snap disk at a predetermined small degree of supercooling is represented by a''-b''-d''.

Therefore, the pressure-temperature characteristic curve a-b-c crosses b'-d' of the off-actuation curve a'-b'-d' at point A, and the on-actuation curve a intersects at point B. ″−b″−b″− of d″
It will cross between d″.

Next, the operation of the switch of the present invention will be explained. Now, if the pressure of the refrigerant in the pipe 1 becomes abnormally high due to insufficient capacity of the condenser, a blockage in the condenser, or a defective fan motor, the pressure will change to the curve a-b-c shown in Figure 3.
rise along the As mentioned above, this curve is defined as
Intersect at a point.

Therefore, at this point, the snap disk 18 is reversed from the state shown in FIG. 1 to the state shown in FIG.
is spaced apart from the fixed contact 21. For this reason, the electrical load 20 such as a relay is turned off, the compressor (not shown) is stopped, and a predetermined pressure control is performed.

When the compressor stops in this way, the pressure of the refrigerant in the cooling system decreases along the curve a-b-c in Fig. 3, and at point B, the pressure of the refrigerant in the cooling system decreases at point B of the on-curve a''-b''-d''. -d'', the snap disk 18 is reversed from the state shown in FIG. 2 to the state shown in FIG. I do.

Next, this operation will be explained with reference to FIGS. 1 and 2. As mentioned above, when the pressure of the refrigerant in the tube 1 rises abnormally, the pressure increases in the gaps 25, 26, 22, 2 between the switch body 3 and the sensing section 4 and the temperature sensing section 9.
3 and 24 to the upper surface of the snap disc 18, and at the same time the pressure inside the sensing part 4 also rises, but when the difference between these pressures reaches a constant value, the snap disc 18 is reversed as described above. The movable contact 17 is instantaneously separated from the constant contact 21. Therefore, there is no malfunction of the contacts, no sparks are generated when the contacts are activated, and no adverse effects on the refrigerant such as carbonization of the refrigerant occur.

In this way, when the pressure of the refrigerant applied to the upper surface of the snap disk 18 decreases, the difference between the pressure of the refrigerant and the refrigerant inside the sensing part 4 gradually decreases until this pressure difference reaches a predetermined value. Then, the snap disk 18 is reversed from the state shown in FIG. 2 to the state shown in FIG.
It instantly closes the contacts and performs predetermined control.
At this time, there is no malfunction of the contacts, and there is no adverse effect on the refrigerant as in the above case.

Further, according to the present invention, when the pressure difference applied to the snap disk 18 reaches a predetermined value at a predetermined large degree of supercooling of the refrigerant, the snap disk 1
Reference numeral 8 inverts the state shown in FIG. 1 to the state shown in FIG. 2, turns off the switch, and can also detect overfilling of the refrigerant in the cooling system.

As described above, the detection switch of the present invention has the effect of being able to detect abnormally high pressure and overfilling of the refrigerant filled in the system of the cooling device. Further, according to the present invention, since only the same refrigerant as the system liquid refrigerant is used as the refrigerant in the sensing section, the overall manufacturing process can be simplified.

[Brief explanation of the drawing]

Fig. 1 is a schematic longitudinal sectional view of the detection switch of the present invention with the contacts closed, Fig. 2 is a longitudinal sectional view of the same with the contacts open, and Fig. 3 is the temperature and pressure of the refrigerant used in the switch of the present invention. A characteristic curve diagram is shown. 1...Pipe, 3...Switch body, 4...Sensing section, 17...Fixed contact, 18...Snap disc, 21...Movable contact.

Claims (1)

[Claims] 1. A tube through which the high-pressure system liquid refrigerant discharged from the compressor passes, a sensing section in which a temperature-sensing section at the end is exposed and only the same refrigerant as the system liquid refrigerant is sealed in this tube, and this sensing section. a snap disk fixed to the pipe and having one side exposed to high-pressure liquid refrigerant and the other side exposed to the refrigerant on the sensing section side; a switch body installed in the tube airtightly so as to surround the sensing section; It consists of a fixed contact supported by the switch body and a movable contact which is operated by reversing the snap disk and also supported by the switch body, and the refrigerant in the sensing part is heated to a predetermined temperature by the compressor and turned into gas. An abnormally high pressure detection switch for refrigerant sealed in a sensing part so as to obtain a pressure-temperature characteristic curve in which the temperature rises but the pressure hardly rises.