JPH06117736A - Detecting device for sealed refrigerant quantity - Google Patents

Abstract

PURPOSE:To provide a sealed refrigerant quantity detection device which is capable of detecting the amount of refrigerant having a proper degree of supercooling at the inlet of an expansion valve in a refrigeration cycle without using a sensor or an arithmetic operation means. CONSTITUTION:A sealed refrigerant quantity detection device 1 is installed closer to a high pressure liquid pipeline 7 on the inlet side of an expansion valve 5 of a refrigeration cycle 30. Refrigerant in a two phase vapor-liquid state is sealed in a chamber 1a on the right-side of the refrigerant quantity detection device 1 while the pressure of refrigerant in the pipeline 7 is arranged to flow into a left-side chamber 1b. The layout of the piping line 7 closer to the device 1 forces the temperature in the right side chamber to be identical to that in the pipeline 7. As a pressure Psc, which is equivalent to that temperature, prevails in the right-side chamber 1a, a differential pressure between the pressure Psc and the pressure Pc in the pipeline 7 moves bellows 11. A display 14 which moves with the bellows 11 serves to determine whether or not the amount of refrigerant is proper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerant filling amount detecting device for detecting a filling amount of refrigerant in a refrigerating cycle used in a refrigerator or an air conditioner.

[0002]

2. Description of the Related Art As shown in FIG. 1, a compressor 2 for compressing a gaseous refrigerant, a condenser 3 for cooling the gaseous refrigerant compressed by the compressor 2 into a liquid refrigerant, and this condenser In the refrigeration cycle 30 including the expansion valve 5 that expands the refrigerant that is liquefied in 3 into a mist-like refrigerant, and the evaporator 6 that heat-exchanges the refrigerant that is atomized in the expansion valve 5 with air, It is conventionally known that when the liquid refrigerant on the inlet side of the valve 5 is appropriately supercooled, the coefficient of performance of the refrigeration cycle 30 is improved.

In order to supercool the liquid refrigerant on the inlet side of the expansion valve 5, it is necessary to properly fill the refrigeration cycle 30 with the refrigerant. However, if the refrigerant is filled too much,
The liquid refrigerant at the inlet of the expansion valve 5 has an excessive degree of supercooling, which rather deteriorates the coefficient of performance. Therefore, it is necessary to detect whether or not the degree of subcooling is appropriate when the refrigerant is charged into the initial refrigeration cycle or when the refrigerant is added.

As a device for detecting the degree of supercooling, there is one which uses a pressure sensor, a temperature sensor, and a calculation means, as disclosed in Japanese Patent Laid-Open No. 3-177762. In this device, the pressure of the refrigerant after the compressor 2 is detected using a pressure sensor, and the degree of supercooling after the condenser 3 at this pressure is 0 °.
The temperature T1 of C is calculated. There is a method in which the actual temperature T2 after the condenser 3 is measured by a temperature sensor and the difference between the temperature T2 and the temperature T1 is calculated to detect the degree of supercooling.

[0005]

However, the above-mentioned conventional supercooling degree detecting device has a problem that the temperature sensor, the pressure sensor, and the calculating means are required, and the device is expensive.

Therefore, in the present invention, the actual amount of refrigerant is appropriate as compared with the amount of refrigerant required to have a proper degree of subcooling at the expansion valve inlet side in the refrigeration cycle without using a sensor or a calculation means. An object of the present invention is to provide a refrigerant enclosure amount detection device capable of detecting whether or not the amount is the amount.

[0007]

In order to achieve the above object, the present invention provides a compressor for compressing a gaseous refrigerant, and a gaseous refrigerant compressed by the compressor to be a liquid refrigerant. A condenser, an expansion valve that expands the liquid refrigerant in the condenser into a mist-like refrigerant, and an evaporator that heat-exchanges the atomized refrigerant with the air, Each of the compressor, the condenser, the expansion valve, and the evaporator is connected by a pipe through which a refrigerant flows, and the refrigerant on the inlet side of the expansion valve is enclosed in a refrigeration cycle having a supercooling degree. In the refrigerant enclosure amount detection device for detecting the refrigerant amount, the temperature sensor has a temperature sensing part for transmitting the temperature of the refrigerant in the pipe between the condenser and the expansion valve, and the inside of the temperature sensing part is the same kind of gas as the refrigerant. A container containing a refrigerant in a liquid two-phase state, and provided on the outer periphery of this container, inside and outside the container And the heat insulating member to insulate the first pressure receiving portion which receives the pressure of the refrigerant in the container, the second receiving a pressure of the refrigerant in said piping between said condenser and said expansion valve
Pressure receiving portion, a pressure difference detecting means for detecting a pressure difference between the pressure received by the first pressure receiving portion and the pressure received by the second pressure receiving portion, and the pressure detected by the pressure difference detecting means. A refrigerant filling amount detection device including a display unit that displays the difference and thus displays whether or not the amount of refrigerant is appropriate is adopted.

[0008]

According to the refrigerant enclosure amount detection apparatus of the present invention having the above-mentioned structure, the refrigerant in the gas-liquid two-phase state in the container is the refrigerant in the pipe between the condenser and the expansion valve due to the temperature sensing portion of the container. Receive the temperature of. Since the container is insulated from the outside by the heat insulating member, the temperature of the refrigerant in the container becomes equal to the temperature of the refrigerant in the pipe.

On the other hand, since the refrigerant in the container is in a gas-liquid two-phase state, the pressure with respect to the temperature is uniquely determined. Therefore, the pressure of the refrigerant in the container is also unique with respect to the temperature of the refrigerant in the pipe. Decided.

The pressure difference between the pressure of the refrigerant in the container received by the first pressure receiving portion and the pressure of the refrigerant in the pipe between the condenser and the expansion valve received by the second pressure receiving portion is detected. It is detected by means. Since the degree of supercooling is proportional to this pressure difference, if the pressure difference can be detected, the degree of supercooling can be detected.
Therefore, by detecting and displaying this pressure difference, it is possible to detect whether or not the refrigerant having an appropriate degree of supercooling at the inlet side of the expansion valve is enclosed in the refrigeration cycle.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the method and apparatus for detecting the amount of enclosed refrigerant of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the refrigeration cycle 30 includes
A compressor 2 for compressing a gaseous refrigerant, a condenser 3 for cooling the gaseous refrigerant compressed by the compressor 2 into a liquid refrigerant, and a mist-like refrigerant for expanding the liquid refrigerant in the condenser 3 The expansion valve 5 and the evaporator 6 for exchanging heat of the atomized refrigerant with the expansion valve 5 with air. Reference numeral 4 is a subcool condenser that supercools the refrigerant so that the high pressure liquid pipe 7 on the inlet side of the expansion valve 5 has a supercooling degree.

When the refrigeration cycle 30 is appropriately filled with a refrigerant, the refrigerant is supercooled by the condenser 3 and the subcool condenser 4, and may have a supercooling degree SC (subcool) as shown in the Mollier diagram of FIG. Known from the past.

A refrigerant filling amount detecting device of the present invention for judging the degree of supercooling will be described with reference to FIGS. 1 and 2.
As shown in FIG. 2, the refrigerant enclosed amount detection device 1 has a hollow quadrangular prism shape, and an expandable / contractible bellows 11 is arranged inside thereof to divide the inside into two chambers. A refrigeration cycle 30 is provided in the right room (right room) 1a, which is one room in the figure.
The same refrigerant that circulates inside is previously filled in a gas-liquid two-phase state and hermetically sealed. The bellows 11 of the device 1 uses a metal bellows in consideration of thermal conductivity and pressure resistance,
It can be expanded and contracted freely. The material of the outer periphery of the device 1 is made of a metal (for example, copper) having good thermal conductivity so that the temperature of the pipe 7 is easily transmitted to the internal refrigerant. The shape of the device 1 is not limited to the hollow quadrangular prism shape, and may be a hollow cylinder shape or the like.

A hole 22 is provided in the side surface of the left room (left room) 1b which is the other room of the apparatus 1. The hole 22 and the insect valve 8 provided in the pipe 7 are connected to the charging hose 10.
Connect by. Hole 22 by charging hose 10
The insect valve 8 is connected to the left chamber 1b of the device 1 and the pipe 7.
By communicating with, the refrigerant in the pipe 7 flows into the left chamber 1b, and the actual pressure in the pipe 7 is introduced. Left ventricle 1b
The left side surface of the bellows 11 shown in FIG.
An indicator 14 for instructing the degree of supercooling is adhered and fixed. The indicator 14 may be made of resin or metal. A sight glass 13 is provided on the upper surface of the left ventricle 1b so that the inside of the left ventricle 1b can be observed, and the position of the indicator 14 can be visually observed from the outside. The left ventricle 1b and the right ventricle 1a are
It is sealed by an O-ring 15.

In order that the temperature of the refrigerant in the pipe 7 is completely transmitted to the refrigerant in the right chamber 1a of the device 1, the heat insulating packing 16 covers the right chamber 1a of the device 1 and the pipe 7, and the external temperature Are not transmitted to the refrigerant in the right chamber 1a.

The bellows 11 expands and contracts in the longitudinal direction of the device 1 in accordance with the pressure difference between the pressure in the right chamber 1a and the pressure in the left chamber 1b, and the indicator 14 moves in the longitudinal direction with it. It is provided. In order to adjust the amount of movement at this time, a spring 12 that applies a force in the longitudinal direction of the device 1 is provided in the right chamber 1a.

FIG. 2B shows a method of displaying the degree of supercooling. The bellows 11 expands and contracts due to the pressure difference between the pressure in the right chamber 1a and the pressure in the left chamber 1b, and the indicator 14 moves accordingly. Therefore, by visually observing this position from the sight glass 13, It is possible to judge whether the cooling degree is optimum.

Further, on the inner circumference of the left chamber 1b, there is provided a stopper 21 projecting toward the inner circumference thereof, and when the bellows 11 extends leftward in the drawing, this stopper 2
1 causes the pointing portion 14 to come into contact with the bellows 11 to limit the extending direction of the bellows 11.

The high-pressure liquid pipe 7 of the refrigeration cycle 30 is provided with a recessed flat portion 7a so that the lower surface 1c of the refrigerant enclosure amount detection device 1 is in close contact. Also, the refrigerant is
In gas-liquid two-phase state, since temperature and pressure are proportional,
Utilizing this characteristic, the right chamber 1a is filled in a gas-liquid two-phase state. The temperature of the refrigerant is 6 at the outlet side of the condenser 3.
It is about 0 ° C. Further, considering that the environment in which the refrigerant is sealed is not an environment below 0 ° C., it suffices to ensure a gas-liquid two-phase state between 0 ° C. and 80 ° C. so that these temperatures can be compensated.

In order to secure the gas-liquid two-phase state between 0 ° C. and 80 ° C., considering the densities of the gas phase and the liquid phase, the amount (W _R ) of the refrigerant to be sealed should be within the following range. It should be inside.

[0022]

[Number 1] _{(ρ G) 80 × V <} W R <(ρ L) 80 × V

[0023]

[Number 2] _{(ρ G) 0 × V <} W R <(ρ L) 0 × V _{where, (ρ G) 80, (} ρ L) 80 is the gas and liquid phases of the refrigerant at 80 ° C. respectively Is the density of. (Ρ _G ) ₀ ,
(Ρ _L ) ₀ is the density of the vapor phase and the liquid phase of the refrigerant at 0 ° C., respectively. Further, V is the right chamber 1a of the refrigerant enclosure amount detection device 1.
Shows the volume of.

The liquid density ρ _L of the refrigerant decreases as the temperature increases, and the gas density ρ _{G of the} refrigerant increases as the temperature increases. Therefore, (ρ _L ) ₈₀ × V and (ρ _L ) ₀ ×
With V, (ρ _L ) ₈₀ × V is smaller. Also,
With (ρ _G ) ₈₀ × V and (ρ _G ) ₀ × V, (ρ _G ) ₈₀ ×
V is larger.

Therefore, the condition satisfying both conditions is equal to the above-mentioned expression 1. Next, the operating principle of the device 1 will be described. First, as shown in FIG. 2, the lower surface 1c of the device 1 is brought into close contact with the flat surface portion 7a of the high-pressure liquid pipe 7. Then, the temperature of the liquid refrigerant inside the pipe 7 is expanded from the lower side surface 1c to make the temperature of the refrigerant inside the right chamber 1a equal to the temperature of the refrigerant inside the pipe 7. At this time, the heat insulating packing 16 formed of a heat insulating material covers the right chamber 1a and the pipe 7 of the apparatus 1 so that the external temperature is not transmitted to the refrigerant in the right chamber 1a.
Therefore, the temperature of the refrigerant in the device 1 becomes equal to the temperature of the refrigerant in the pipe 7.

As shown in the Mollier diagram of FIG. 10, the pressure with respect to temperature is uniquely determined in the gas-liquid two-phase refrigerant. When the refrigeration cycle 30 on the Mollier diagram is shown by a solid line 31, when the refrigerant on the inlet side of the expansion valve 5 has a subcool SC, the refrigerant on the inlet side of the expansion valve 5 has a pressure of Pc [Kg / cm ² abs] and the temperature is B (° C). The pressure Psc on the saturated liquid line 40 of the refrigerant with respect to the temperature B (° C) of the refrigerant on the inlet side of the expansion valve 5 is calculated, and the pressure difference ΔP (= Pc- between the pressure Psc and the state pressure Pc).
Psc). Since the subcool amount SC is proportional to the pressure difference ΔP, if the pressure difference ΔP is obtained, the subcool amount SC is obtained.

By the way, in the present device 1, when the temperature of the refrigerant in the device 1 becomes equal to the temperature of the refrigerant in the pipe 7, the refrigerant in the right chamber 1a is on the dotted line 32 in the gas-liquid two-phase state. , The pressure for that temperature is uniquely determined. That is, to explain corresponding to the above description of FIG. 10, the right ventricle 1a
The internal pressure becomes the pressure Psc on the saturated liquid line 40 with respect to the temperature B (° C) of the refrigerant in the pipe 7.

The bellows 11 expands and contracts due to the pressure difference between the pressure Psc of the refrigerant in the right chamber 1a and the pressure Pc of the refrigerant in the pipe 7 flowing into the left chamber 1b. By detecting the pressure difference as the expansion / contraction amount, it is determined whether or not the refrigerant is sealed in the refrigeration cycle in an amount capable of having an appropriate degree of supercooling on the inlet side of the expansion valve 5.

As shown in FIG. 10, the degree of supercooling is small,
When the refrigeration cycle 30 is formed as shown by −′−′−, the temperature C (° C) of the refrigerant in the pipe 7 is high,
The pressure Psc 'corresponding to the temperature C (° C) is large.
At this time, the pressure Pc in the pipe 7 and the pressure P in the right chamber 1a
The pressure difference from sc ′ is small, and the force of the refrigerant in the pipe 7 pushing the bellows 11 to the right is slightly larger. Since the spring 12 is interposed in the right chamber 1a, the bellows 11
Is pushed to the left side to be in an extended state, the indicator 14 approaches the left ventricle 1b, and in FIG. 2B, the degree of supercooling is smaller to balance.

On the other hand, the degree of supercooling is large, and
When the refrigeration cycle 30 is formed as shown in FIG.
The temperature B (° C) of the internal refrigerant is low, and the temperature B (° C)
The pressure Psc corresponding to is small. At this time, the pressure difference between the pressure Pc in the pipe 7 and the pressure Psc in the right chamber 1a is large, and the force of the refrigerant in the pipe 7 pushing the bellows 11 to the right is considerably larger. Therefore, the bellows 11 contracts and the indicator 14 moves to the right.

In this way, it is possible to detect whether or not the amount of the refrigerant enclosed is an appropriate amount for providing the degree of supercooling. Next, the time when the refrigerant is charged will be described.

At the initial stage of refrigerant charging, when the refrigerant amount is small and there is no supercooling degree, the refrigerant in the pipe 7 is in a gas-liquid two-phase saturated state, and there is almost no pressure difference because Pc = Psc. In this state, the bellows 11 is fully extended and the stopper 21 is in contact with the indicator 14. from now on,
The pressure Psc in the right chamber 1a gradually decreases as the degree of supercooling begins to be gradually increased and the refrigerant gradually increases, and the pressure Pc in the pipe 7 and the pressure Ps in the right chamber 1a gradually increase.
The pressure difference from c increases. Then bellows 1
No. 1 shrinks as the degree of supercooling increases.

Therefore, as shown in FIG. 2 (B), if the charging of the refrigerant is stopped at the position where the indicator 14 indicates the proper state,
The amount of refrigerant having an appropriate degree of supercooling can be set. In addition, as shown in FIG. 6, the subcool cycle has an optimum degree of supercooling that maximizes cycle efficiency depending on the cooling load (refrigerant flow rate). That is, even in the situation when the refrigerant is charged, the cooling load changes depending on the outside air temperature, and the optimum degree of supercooling changes. Since the optimum degree of supercooling varies depending on the outside air condition when the refrigerant is charged, as shown in FIG. 5, if a plate in which the position of the optimum degree of supercooling with respect to the outside temperature is specified is attached on the sight glass 13 in advance. Even if the outside air condition changes significantly, if the instruction of the indicator comes at a position corresponding to the outside air condition, if the refrigerant charging is stopped, it is possible to always charge the refrigerant so that the degree of supercooling is optimum. In the present embodiment, the outside air conditions are classified into three types, summer, spring / autumn, and winter.
It is not limited to this, and may be classified into more cases than this.

A second embodiment of the present invention is shown in FIGS. As shown in FIG. 3, a room in which the temperature of the high-pressure liquid pipe 7 of the refrigeration cycle 30 is transmitted is provided separately from the right room 1a, and the same refrigerant as the refrigerant in the refrigeration cycle 30 is enclosed in the room. An enclosure chamber 17 is provided. Refrigerant enclosure chamber 1
In the same manner as in the first embodiment, 7 is filled with a refrigerant in a gas-liquid two-phase state, and the capillary tube 18 is used to fill the refrigerant enclosure chamber 1.
7 and the right ventricle 1a.

In this structure, the temperature of the refrigerant in the pipe 7 is transmitted to the refrigerant enclosing chamber 17, and the pressure in the refrigerant enclosing chamber 17 becomes a pressure corresponding to the temperature, and the pressure in the right chamber 1a is passed through the capillary 18. The pressure Psc is transmitted.

In this embodiment, the shape of the pipe 7 remains cylindrical, and the lower surface of the refrigerant enclosure chamber 17 is as shown in FIG.
By having a semicircular cross section, the contact area is increased so that the temperature of the pipe 7 can be easily transmitted. Further, the refrigerant sealing chamber 17 and the pipe 7 are attached so as to be in close contact with each other, and the heat insulating packing 20 is wound from the outer peripheral side thereof.

As described above, a temperature sensitive portion for transmitting the temperature in the pipe 7 may be provided separately. The operation of the second embodiment is the same as that of the first embodiment. Next, the third and fourth embodiments of the present invention are shown in FIGS.

In the third embodiment shown in FIG. 7, a refrigerant chamber 17 corresponding to the right chamber 1a in the first embodiment is provided, and this refrigerant chamber 17 is closely attached to the pipe 7. Then, the pressure of the refrigerant inside the refrigerant chamber 17 becomes a pressure corresponding to the temperature of the refrigerant flowing through the high-pressure liquid pipe 7. Therefore, the pressure is measured via the capillary tube 18. On the other hand, the actual pressure is measured from the insect valve 8 via the capillary tube 10. Then, this pressure difference is obtained. As in the above embodiment, as the degree of supercooling increases, the pressure inside the refrigerant chamber 17 decreases and the differential pressure in the differential pressure gauge increases. Also, depending on the conditions of winter, spring, autumn, and summer, the optimum degree of supercooling becomes large and the differential pressure also becomes large. Therefore, it is advisable to clearly indicate the optimum value under each condition on the differential pressure gauge as shown in FIG.

In the fourth embodiment shown in FIG. 9, a very small amount of the refrigerant in the refrigeration cycle 30 is allowed to flow into the supercooling degree detecting device 60, and this refrigerant is used for detection. The detection device 60 of this embodiment has therein a differential pressure type 25 corresponding to each part of the third embodiment, a refrigerant chamber 17, and capillary tubes 10 and 18.
Is provided. In order to allow a minute amount of refrigerant to flow into the device 60, the refrigerant on the inlet side of the expansion valve 5 is caused to flow from the insect valve 8 into the charging hose 50, and the refrigerant chamber 17
The temperature of the refrigerant inside is set to this temperature, and this refrigerant is caused to flow into the refrigeration cycle 30 through the valve 81 on the low pressure side. At this time, the throttle 51 for reducing the pressure of this refrigerant reduces the pressure by a pressure substantially equal to the pressure reduction amount in the expansion valve 5. The operation of the configuration of this embodiment is similar to that of the third embodiment shown in FIG. According to this configuration, it is not necessary to care about the adhesion of the refrigerant chamber 17 to the pipe 7, and it is sufficient to connect the insect valves 8 and 81 and the charging hose 50 and the like, and the operation is easy.

In the above embodiment, the heat transfer is better when the liquid surface side of the refrigerant in the gas-liquid two-phase state in the right chamber 1a in which the refrigerant is sealed is in close contact with the pipe 7.

[0041]

As described above, in the refrigerant enclosure amount detection device of the present invention, the temperature of the refrigerant in the pipe between the condenser and the expansion valve is transmitted to the inside, and the same type as the refrigerant in the refrigeration cycle. Of the gas-liquid two-phase refrigerant, a first pressure transmitting section for transmitting the pressure of the refrigerant in the vessel, and a second pressure transmitting section for transmitting the pressure of the refrigerant in the pipe between the condenser and the expansion valve. Of the refrigerant in the container, and a pressure difference detecting means for detecting a pressure difference between the pressure transmitted by the first pressure transmitting section and the pressure transmitted by the second pressure transmitting section. The temperature is made equal to the temperature of the refrigerant in the pipe, and the pressure of the refrigerant in the container at this temperature is compared with the pressure of the refrigerant in the pipe to detect the pressure difference. From this pressure difference, it is possible to detect whether or not an appropriate amount of refrigerant is enclosed in the refrigeration cycle.

Therefore, the actual amount of refrigerant is appropriate to the amount of refrigerant required to have a proper degree of supercooling at the inlet side of the expansion valve in the refrigeration cycle without using a sensor or calculating means as in the conventional case. It is possible to provide a refrigerant enclosure amount detection device capable of detecting whether or not the amount is the amount.

[Brief description of drawings]

FIG. 1 is a diagram showing how a supercooling degree detector of the present invention is attached to a refrigeration cycle.

FIG. 2A is a cross-sectional view of the essential parts showing the first embodiment of the supercooling degree detector of the present invention. (B) is a top view showing a first embodiment of the supercooling degree detector of the present invention.

FIG. 3 is a sectional view of an essential part showing a second embodiment of the supercooling degree detector of the present invention.

FIG. 4 is a sectional view showing a temperature sensing portion of a second embodiment of the supercooling degree detector of the present invention.

FIG. 5 is a plan view showing a display portion of the supercooling degree detector of the present invention.

FIG. 6 is a diagram showing a relationship between a refrigerant flow rate and a supercooling degree.

FIG. 7 is a schematic view showing a third embodiment of the present invention.

FIG. 8 is a diagram showing a differential pressure gauge.

FIG. 9 is a diagram showing a fourth embodiment of the present invention.

FIG. 10 is a diagram showing a Mollier diagram.

[Explanation of symbols]

 1 Refrigerant enclosure amount detection device 2 Compressor 3 Condenser 5 Expansion valve 6 Evaporator 7 High pressure side pipe 8 Bug valve

Claims (1)

[Claims] 1. A compressor for compressing a gaseous refrigerant, a condenser for cooling the gaseous refrigerant compressed by the compressor to a liquid refrigerant, and an expansion of the liquid refrigerant in the condenser. An expansion valve for converting the atomized refrigerant into an atomized refrigerant, and an evaporator for exchanging heat of the atomized refrigerant with the air, the compressor, the condenser, the expansion valve, and the evaporator. In the refrigerant enclosure amount detection device for detecting the amount of refrigerant enclosed in the refrigeration cycle in which the refrigerant on the inlet side of the expansion valve has a supercooling degree, the refrigerant is connected to each other by a pipe through which the refrigerant flows, A container having a temperature-sensing part for transmitting the temperature of the refrigerant in the pipe between the expansion valve and the expansion valve, and containing therein a refrigerant in a gas-liquid two-phase state of the same kind as the refrigerant, and the outer periphery of the container A heat insulating member that is installed in the container to insulate the inside and the outside of the container, and receives the pressure of the refrigerant in the container. A first pressure receiving portion, a second pressure receiving portion that receives the pressure of the refrigerant in the pipe between the condenser and the expansion valve, a pressure received by the first pressure receiving portion, and a second pressure receiving portion that receives the pressure. And a pressure difference detection means for detecting a pressure difference from the pressure received by the pressure receiving part of, and a pressure difference detected by the pressure difference detection means.
Accordingly, a refrigerant filling amount detection device comprising: a display unit that displays whether or not the amount of refrigerant is appropriate.