JPH0510192Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a switch for detecting overfilling of refrigerant in a refrigeration system, which operates depending on the value of the degree of subcooling of high-pressure refrigerant.

Conventional means for detecting overfilling of refrigerant in refrigeration equipment include sight glasses, high-pressure switches, and safety valves installed in the high-pressure system of refrigerant equipment, but sight glasses require skill to monitor the flow of refrigerant liquid. However, high-pressure switches and safety valves have the disadvantage that early detection is difficult because they operate based on pressure.

This project was devised to eliminate the above-mentioned drawbacks, and focuses on the fact that when refrigerant is overfilled in the system, the degree of subcooling increases compared to normal charging. To provide early and reliable detection, a switch is provided that operates depending on the value of the degree of subcooling of the refrigerant on the high pressure side.

That is, according to the present proposal, there is a tube through which the high-pressure liquid refrigerant discharged from the compressor passes, a temperature-sensing section with an exposed temperature-sensing section at the end inside this tube, and a side of the temperature-sensing section corresponding to the temperature-sensing section. A stopper with a hole in the center is installed on the upper surface of the stopper so that its periphery is airtight with respect to the stopper, and one side is exposed to high-pressure liquid refrigerant and the other side is exposed to the refrigerant on the sensing part side. a snap disk, a switch body provided airtightly in the tube so as to surround the sensing section, a lid tightly inserted into the switch body, a fixed contact supported by the above; It is actuated by reversing the snap disk, and has one end fixed to a switch mounting plate held between the lid and the sensing section, and a movable contact supported at the other end of the switch lever. When the system is normal, the pressure chamber applied to the snap disk is filled with a small refrigerant, and the pressure of the refrigerant applied to both sides of the snap disk increases depending on the degree of supercooling of the high pressure side refrigerant. When the difference reaches a predetermined value, the contact is rapidly reversed to open and close the contact.

Furthermore, when the degree of subcooling of the high-pressure liquid refrigerant increases due to overfilling of the refrigerant in the cooling system, the pressure of the refrigerant gas sealed in the sensing part after passing through the temperature sensing part decreases, causing As the pressure difference applied to the snap disk increases, the snap disk is reversed from convex to concave, and as a result, the movable contact is separated from the fixed contact, the electric circuit is opened, the compressor is stopped, and a predetermined temperature control is performed.

Also, in the above condition, when the value of the degree of supercooling decreases, the pressure of the refrigerant gas sealed in the sensing part through the temperature sensing part increases, and the pressure difference applied to the snap disc becomes smaller, so the snap disc moves away from the concave position. As a result, the movable contact contacts the fixed contact, the electric circuit is closed, and the compressor starts operating to perform predetermined temperature control.

Therefore, in the present invention, the switch can be operated depending on the degree of subcooling of the refrigerant on the high pressure side, regardless of the temperature and pressure of the refrigerant.

Next, an embodiment of the present invention shown in the drawings will be described. Reference numeral 1 denotes a pipe through which high-pressure 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. Inside the switch body 3 is a cylindrical sensing section 4.
is housed and supported by engaging the peripheral lower surface 6 of the upper stopper 5 with the step 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 made of a suitable insulator is inserted inside the upper part of the switch body 3, and a switch mounting plate 11 is sandwiched between the lower surface of the lid 10 and the upper surface of the sensing section 4. The upper edge 12 of the switch body 3 is crimped against the lid 10 to hold the lid 10 within the switch body 3. 1
3 is an O-ring provided on the outer periphery of the lid and the inner periphery of the switch body 3.

One end of a switch lever 14 is fixed to the switch mounting plate 11, and a movable contact 15 is provided at the other end.

A disk-shaped snap disk 16 is attached to the upper surface of the stopper 5 so that its peripheral edge is airtight with respect to the stopper. A spring piece 1 is provided between the switch lever 14 and the snap disk 16.
7 is provided.

A terminal 18 is inserted into the lid 10 , one end is connected to an electrical load 19 such as a relay, and the other end has a fixed contact 20 facing the movable contact 15 . 21 is terminal 18 and lid 10
This is an O-ring installed between the

However, the stopper 5 and the switch mounting plate 11,
A small gap 2 is provided between the switch body 3 and the switch body 3 by appropriate means.
2, 23, 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.

27 is a joint provided between the switch body 3 and the pipe 1, and 28 is an O-ring provided between this joint and the switch body 3. Thus, FIG. 1 shows the main switch in a closed state, and FIG. 2 shows the main switch in an open state.

Next, to explain the above-mentioned degree of supercooling, curve A in Fig. 3 shows a saturated vapor pressure characteristic curve when the horizontal axis is the temperature of the enclosed refrigerant and the vertical axis is the pressure. When the temperature T of the refrigerant is lower than the saturation temperature T ₀ at that pressure, this is called a supercooled state, and the difference T ₁ from the saturation temperature is called the degree of supercooling.

The same type of refrigerant is sealed in the cooling system including the tube 1 and in the sensing section 4.

If the refrigerant is overfilled in the cooling system, and the above-mentioned degree of supercooling increases, the refrigerant temperature in the system will change between the temperature sensor 9 gaps 26, 25, the small gaps 22, 23,
24 to the sensing section 4, and the temperature and pressure of the refrigerant inside the sensing section are lowered. For this reason, the pressure difference applied to the snap disk 16 increases, and the snap disk 16 is reversed from the convex state shown in FIG. 1 to the concave state shown in FIG. Due to the elasticity of the movable contact 15, the movable contact 15 is separated from the fixed contact 20, the electric load 19 such as a relay stops operating, and predetermined temperature control is performed.

When the value of the degree of supercooling decreases, contrary to the above, the pressure of the refrigerant in the sensing part 4 increases, and the pressure difference applied to the snap disk 16 decreases, causing the snap disk 16 to move from the concave state shown in FIG. The movable contact 15 is reversed to the convex state shown in FIG.
is in contact with the fixed contact 20, the electric load resumes operation, and predetermined temperature control is performed.

Next, Figure 4 shows the same parts as in Figure 3 with the same symbols.
The opening/closing operation of the switch will be explained with reference to the figures.

Suppose that the high-pressure liquid refrigerant in the cooling system including tube 1 has now moved from point a to point b at the degree of supercooling ΔT.
The pressures of the liquid refrigerant on the high pressure side and the refrigerant in the sensing part 4 at the point are both _P1 because the saturated vapor pressure characteristic curve of the refrigerant in the sensing part is the same as the curve A. The applied pressure difference ΔP is zero.

Next, at point b, the pressure within the system is _P1 , but the pressure within the sensing section 4 becomes _P2 due to the temperature drop as described above. Therefore, the pressure difference ΔP applied to the snap disk becomes P ₁ −P ₂ .

During this period, if the snap disc is made to reverse from the convex state shown in Figure 1 to the concave state shown in Figure 2 at point c (supercooling degree ΔT ₁ ) where the pressure difference ΔP becomes Ph, the snap disc will be reversed. Then, as described above, the movable contact 15 is separated from the fixed contact 20.

Next, when the supercooled state changes from point b to point a, the pressure difference ΔP becomes smaller and ΔP becomes Pf on the way d
Snap disk 1 at point (degree of supercooling ΔT ₂ )
If 6 is reversed from the concave state shown in Figure 2 to the convex state shown in Figure 1, the snap disc will be reversed.
The contacts are closed and the control described above is performed.

Here, the curve X shown by the dotted line indicates that the pressure difference ΔP applied to the snap disc 16 at a certain degree of supercooling is Ph
The curve Y connects the operating points of the snap disk when , and opens the contact, and the curve Y similarly closes the contact when the pressure difference ΔP is Pf.

As described above, according to the present invention, overfilling of the cooling system with refrigerant can be detected based on the value of the degree of subcooling, so it can be detected much earlier and more reliably than with conventional methods. be.

In addition, in this case, since the pressure difference applied to the snap disc increases only when the refrigerant is overfilled, the stress applied to the snap disc during normal operation is small, making it possible to manufacture this type of highly reliable switch. Since the refrigerant in the sensing section does not require special techniques such as mixing nitrogen gas or the like to increase the pressure, this type of switch also has the advantage of being easy to manufacture.

The operating value of the snap action of the snap disk is stabilized, excessive deformation of the snap disk is suppressed, and characteristics do not change even when abnormal pressure is applied.

Furthermore, according to the present invention, assembly is simplified, variations in the positions of the snap disc and the switch lever are kept small, and the opening/closing operation of the switch is ensured.

[Brief explanation of the drawing]

1 and 2 are schematic vertical sectional views of the switch of the present invention, with FIG. 1 showing the switch in a closed state and FIG. 2 showing it in an open state. FIG. 3 is a curve diagram for explaining the degree of supercooling, and FIG. 4 is a curve diagram for explaining the operation of the switch due to changes in the value of the degree of supercooling. 1...Pipe, 3...Switch body, 4...Sensing section, 15...Movable contact, 16...Snap disc, 20...Fixed contact.

Claims (1)

[Scope of utility model registration request] A tube through which the variable pressure liquid refrigerant discharged from the compressor passes, a sensing section with an exposed temperature-sensing section at the end inside this tube, and a central section installed on the side corresponding to the temperature-sensing section of this sensing section. a stopper having a hole; a snap disk attached to the upper surface of the stopper so that its periphery is airtight with respect to the stopper; one side of the snap disk is exposed to a variable pressure liquid refrigerant and the other side is exposed to a refrigerant on the sensing section side; A switch body provided airtightly in a tube so as to surround a sensing section, a lid tightly inserted inside the switch body, a fixed contact attached to this lid, and the lid and sensing section. It consists of a switch mounting plate held between the switch mounting plate, a switch lever which is fixed at one end to the switch mounting plate and is activated by reversing the snap disc, and a movable contact provided at the other end of the switch lever. The sensing section is filled with refrigerant that has a small pressure difference across the snap disk when the system is normal, and the snap disk is heated on both sides depending on the degree of supercooling of the refrigerant on the transformation side. A refrigerant overfill detection switch that rapidly reverses to open and close the contacts when the pressure difference between the applied refrigerants reaches a predetermined value.