JPH089581Y2 - Outside temperature sensitive pressure switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a pressure switch used for detecting a high pressure of a refrigeration cycle to detect a shortage of a refrigerant gas in the cycle.

[Conventional technology]

Lack of refrigerant gas in the refrigeration cycle is a fatal problem,
Accidents such as deterioration of refrigeration capacity or damage to the compressor occur.

Therefore, if the gas is insufficient, the refrigerant circulation rate will decrease, so the pressure on the high-pressure side will drop from the normal value.Use the characteristic that a pressure switch is installed on the high-pressure side, and when the pressure becomes lower than the set value, the contact is turned off and the refrigeration cycle It is designed to stop the operation of.

However, the conventional pressure switch has a structure as shown in FIG. 4, and the contact point A, by the load balance between the receiving member R that receives the pressure P and the bias member 2 that opposes it.
When B is opened and closed, and the pressure receiving pressure P becomes smaller than the load of the bias member S, the contact is turned off and the operation of the refrigeration cycle is stopped. And that value operates at a constant value (eg 2.1 kgf / cmG) regardless of temperature.

[Problems to be solved by the device]

However, the high-pressure pressure of the refrigeration cycle changes to the saturation pressure according to the outside temperature when the refrigeration cycle stops because the condensation temperature of the condenser changes depending on the outside temperature.
(Fig. 5) Therefore, when the set pressure of the pressure switch is increased in order to detect the gas shortage at an early stage, there is a problem that the refrigeration cycle cannot be operated even if the gas is normally filled when the outside air temperature is low. , The pressure drop line of the refrigeration pressure cycle (5th
In contrast to (indicated by the dotted line in the figure), since the set pressure of the pressure switch is constant, there is also a problem that the detection capability at high load with high outside air temperature becomes poor.

That is, even when the gas is insufficient, the pressure of the refrigerant becomes high when the outside air temperature is high, and the switch is turned on to operate the compressor, causing an accident such as burning.

Therefore, in the conventional device, the set pressure of the pressure switch is set to 2.1 kgf / cm ² G as described above to enable the operation of the refrigeration cycle when the outside temperature is zero degrees or more, and it is impossible to detect the gas shortage at an early stage. It has become a thing.

This plan controls the set pressure of the pressure switch so that the set pressure is low when the outside air temperature is low and the set pressure is high when the outside air temperature is high, and early detection of gas shortage in the refrigerant cycle regardless of whether the outside air temperature is low or high. The purpose is to provide a pressure switch that can.

[Means for solving the problem]

In order to achieve the above object, the present invention switches a temperature sensing part that senses the outside temperature to the outside of the switch and a pressure sensing part that converts the pressure from this temperature sensing part into a load and applies a load opposite to the pressure of the refrigeration cycle. It is provided inside and the operating pressure is changed according to the outside air temperature.

[Action]

Since the present invention has the means as described above, the operating pressure of the switch changes in proportion to the pressure applied to the pressure receiving portion, that is, the bellows through the temperature sensing portion. After that, the pressure of the refrigerant applied to the diaphragm becomes low, but the pressure in the bellows also becomes low and the operating pressure of the switch becomes low. Therefore, the switch can be operated in this state. Now, when the gas in the refrigeration cycle is insufficient when the outside air temperature is low, the refrigerant pressure in the refrigeration cycle is reduced to the operating pressure of the switch or less, so the switch is turned off and the compressor is stopped. Therefore, it is sufficient to fill and supplement the gas at this point. Also, when the outside air temperature rises, the gas pressure in the refrigeration cycle rises contrary to the previous term, but the gas pressure in the bellows rises, and the operating pressure of the switch rises in proportion to it, so early detection of gas shortage is possible. It will be possible. If the gas in the refrigeration cycle becomes insufficient even if the outside air temperature has risen, the refrigerant pressure in the refrigeration cycle drops and immediately falls below the switch operating pressure, so the switch turns off and the compressor stops.

 Therefore, it is sufficient to fill and supplement the gas at this point.

〔Example〕

 An embodiment shown in the drawings will be described below.

In FIG. 1, reference numeral 1 denotes a switch body, which has a communication hole 2 connected to piping of a refrigeration cycle and a diaphragm chamber 3 communicating with this communication hole. Reference numeral 4 denotes an inverted cup-shaped cover fixed to the main body, and 5 denotes a seal member.

A diaphragm 6 is sandwiched between the main body 1 and the cover 4 via a seal member 5.

Two terminals 7 and 8 are fixed to the cover 4, and conductive portions 9 and 10 are provided on the lower surfaces of the terminals in the figure.
A receiving member 11 whose one surface is in contact with the diaphragm 6 is provided on the cover side of the diaphragm, and a projection 12 is provided on the opposite side of the receiving member to the diaphragm 6.

Reference numeral 13 denotes a movable contact member, which has a convex shape, and has a hole 14 in the center thereof, through which the projection 12 of the receiving member 11 is fitted and projected upward in the drawing. The leg portion 15 is in contact with the upper surface of the receiving member 11, and has a conductive portion 16 on the opposite side (upper surface in the drawing) opposite to the conductive portions 9 and 10 of the terminals 7 and 8.

Reference numeral 17 denotes a movable guide portion provided in the cover 4, and the projection 12 of the receiving member 11 is in contact with a lower recess 18 in the figure. Reference numeral 19 denotes a spring, which is inserted between the cover 4 and the guide portion 17.

Therefore, the guide portion 17 is pressed by the spring pressure of this spring into the contact member
Is pressed against the upper surface 13a.

In addition, a bellows 20 is arranged in the internal space of the coil-shaped spring 19 in the cover 4, and the bellows 20 is composed of a fixing member 21 having a hermetically expanding and contracting portion and a connecting cylinder portion having a hole formed therein. By fitting and fitting the connecting tube portion of the fixing member 21 into the cover 4, it is attached and fixed to the cover 4. A thin tube 23 is airtightly inserted into the opening of the fixing member 21, and the thin tube 23 is connected to a temperature sensing portion 22 that senses the outside air temperature. The sealing and expanding portion of the bellows 20, the thin tube 23 and the temperature sensing portion. Refrigerant is enclosed in 22. When the pressure of the refrigerant changes due to the temperature change of the temperature sensing part 22, the expansion / contraction part of the bellows 20 expands / contracts to change the pressing force to the guide part 17 so that the end part of the expansion / contraction part can move.

The switch body 1 thus constructed is arranged in the refrigeration cycle shown in FIG. That is, in FIG. 2, Co is a compressor, C is a condenser, D is a receiver dryer, Ex is an expansion valve, and E is an evaporator.

The temperature sensing section 22 is preferably provided along the condenser C.

Since the switch of the present invention has the structure as described above, the movement of each conductive part is caused by the force F ₁ generated on the receiving member 11 by the cycle pressure P in the diaphragm chamber 3 and the temperature T of the temperature sensing part 22 applied from the opposite direction. Caused by the load balance between the force F ₂ due to the pressure P _T inside the bellows 20 and the spring pressure F ₃ due to the spring 19, and the load balance is ΔF, ΔF = F ₁ − (F ₂ + F ₃ ) and ΔF> 0 The conductive part is closed when, and the conductive part is opened when ΔF <0.

Therefore, ΔF = 0, that is, when F ₁ − (F ₂ + F ₃ ) = 0, indicates the operating point of this switch.

Here, F ₁ = P · A ₁ : A ₁ is the effective pressure receiving area of the diaphragm, and F ₂ = P _T A ₂ : A ₂ is the effective pressure receiving area of the movable guide portion, so P = A ₂ / A ₁ · since _{P T + 1 / a 1 ·} F 3 becomes a _1, a _2, F ₃ are immutable once set, the above formula becomes the P varies in proportion to changes in P _T, P _T is the temperature Since the temperature changes in a constant relationship with T, the switch of the present invention changes P in a constant relationship according to the outside air temperature T.

The specific setting examples of each value and the operating pressure characteristics are shown below.

The enclosed gas in the temperature sensing section 22 was the same as the refrigerant gas used in the cycle (for example, Freon 12).

When A ₁ = 1cm ² , A ₂ = 0.78cm ² and F ₃ = 0.462kgf, the working pressure characteristics shown in Fig. 3 are shown and the outside temperature is 0 ℃.
It operates at 2.1kgf, which is the same as the conventional switch, and it can be seen that the operating pressure rises as the outside air temperature rises, thus enhancing the gas shortage detection capability. Further, since the operating pressure is always lower than the cycle pressure, it can be seen that there is no problem in starting the cycle operation.

[Effect of device]

As can be understood from the above, in the pressure switch according to the present invention, the operating pressure increases and decreases with a constant relationship with respect to the change in the outside air temperature, so that the refrigerant gas in the refrigeration cycle is insufficient regardless of the outside air temperature. In addition to being able to find out, it is possible to prevent malfunction of the equipment by enabling the switch operation in the low temperature range and improve the reliability of the refrigeration cycle.

Also, by adopting the bellows as the pressure responsive member, the response of the pressure switch can be improved, and
Since the bellows is arranged in the inner space of the coiled spring and the coiled spring and the bellows cooperate with each other to exert a pressing force on the concentrically movable guide portion, the entire pressure switch becomes compact. In addition, the pressing force acts on the entire movable guide portion in a well-balanced manner.

Further, the bellows can be easily and easily attached and fixed to the cover by fitting and fitting the connecting tube portion of the bellows into the opening of the cover without requiring any other fixing member. By inserting a thin tube into the opening of the section, it is possible to communicate with the temperature sensing section in a sealed manner.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of the proposed switch, FIG. 2 is a view showing a mounting plate of the proposed switch to a refrigeration cycle, and FIG. 3 is a relational diagram between an operating pressure of the proposed switch and an outside air temperature of the refrigeration cycle. FIG. 4 is a schematic sectional view of a conventional switch, and FIG. 5 is a relationship diagram between the operating pressure of the conventional switch and the outside air temperature of the refrigeration cycle. 1 ... Switch body, 2 ... Communication hole, 3 ... Diaphragm chamber, 4 ... Cover, 6 ... Diaphragm, 7,8 ... Terminal, 11 ... Receiving member, 13 ... Contact member, 17 ... Information section,
19 …… Spring, 20 …… Bellows, 22 …… Temperature sensing part.

Claims (1)

[Scope of utility model registration request] 1. A switch main body having a diaphragm chamber connected to a refrigeration cycle, an insulator cover projecting two terminals having a conductive portion, and the switch main body and the insulator cover. And a diaphragm disposed in the diaphragm chamber, and in the insulator cover on the side opposite to the diaphragm chamber, one surface is in contact with the diaphragm and a receiving member having a protrusion in the center of the other surface, and one surface is the A convex movable contact member having a conductive portion which is in contact with the receiving member and which faces the conductive portions of the two terminals on the other surface, and a spring which is in contact with the contact member on one surface and the other surface is on the other surface of the insulating cover. In an outside air temperature sensitive pressure switch having a bellows and a movable guide portion in contact with the bellows, the bellows is disposed in an inner space of the spring and has an opening for connecting the temperature sensing portion. An outside air temperature sensing, comprising a fixed member having a connecting tube portion provided and a hermetically expanding / contracting portion, wherein the hermetically expanding / contracting portion cooperates with the spring to press the movable guide portion in the diaphragm direction. Type pressure switch.