JP3213440B2 - Expansion valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to the temperature of a refrigerant sent from an evaporator in a refrigeration cycle to a compressor.
The invention relates to an expansion valve for automatically controlling the amount of refrigerant entering an evaporator.

[0002]

2. Description of the Related Art In general, an expansion valve of this type is provided with a temperature-sensitive cylinder filled with a saturated vapor gas which is the same as or similar to the refrigerant flowing through a refrigeration cycle in an outlet side passage of an evaporator. The valve mechanism is driven by the displacement of the diaphragm provided in the temperature-sensitive chamber communicating with the air-conditioning chamber to control the flow rate of the refrigerant sent to the evaporator.

However, it is difficult to precisely control the expansion valve in an environment where the load condition and the outside air condition fluctuate greatly, and the degree of superheat of the refrigerant at the evaporator outlet side is inappropriate. Become.

Therefore, conventionally, an inert gas is enclosed together with a saturated steam gas in a temperature sensing chamber, and an electric heater is provided in an auxiliary temperature sensing cylinder communicating with the temperature sensing chamber, and the auxiliary temperature sensing cylinder is heated as necessary. Thus, the pressure of the inert gas is increased to increase the valve opening. Thereby, even if the temperature of the refrigerant sent out from the evaporator is the same, the flow rate of the refrigerant sent into the evaporator increases, and the degree of superheat of the refrigerant can be made appropriate.

[0005]

However, in the conventional expansion valve as described above, when it is necessary to lower the gas temperature inside the auxiliary temperature sensing cylinder from the state where the auxiliary temperature sensing cylinder is heated, the temperature rises. Since the time constant of the descent is large, even if the heater is turned off, it takes a considerable amount of time for the gas temperature to drop, and during that time, the degree of superheating of the refrigerant becomes inadequate.

Accordingly, the present invention provides an expansion valve which uses a heater for increasing the gas pressure in a temperature-sensitive chamber, has a small time constant when lowering the temperature, and can always maintain the refrigerant superheat degree appropriately. The purpose is to provide.

[0007]

In order to achieve the above-mentioned object, an expansion valve according to the present invention is arranged so as to sense the temperature of a refrigerant flowing out of an evaporator and has a saturated steam gas sealed therein. An expansion valve having a diaphragm arranged so as to form one wall surface of the temperature sensing chamber, and a valve mechanism driven by displacement of the diaphragm to change a flow rate of refrigerant entering the evaporator. An inert gas is enclosed in the greenhouse together with the saturated vapor gas, and a heater for heating the temperature-sensitive chamber is provided at a position not in contact with the diaphragm.

[0008]

[Function] Even if the temperature of the refrigerant flowing out of the evaporator does not change,
When it is necessary to increase the flow rate of the refrigerant to be sent into the evaporator, the temperature-sensitive chamber is heated by operating the heater, the temperature of the gas inside rises quickly, and the pressure of the inert gas increases, so that the valve The opening increases.

Since the temperature-sensitive chamber is always cooled by the refrigerant flowing out of the evaporator, if the operation of the heater is stopped, the gas temperature in the temperature-sensitive chamber drops rapidly, the valve opening decreases, and the temperature in the evaporator decreases. The flow rate of the supplied refrigerant decreases.

[0010]

An embodiment will be described with reference to the drawings. FIG. 1 shows a refrigeration cycle, and 1 is an evaporator. 2 is a compressor. 3
Is a condenser. Reference numeral 4 denotes a receiver connected to the outlet side of the condenser 3 and containing a high-pressure liquid refrigerant. 10 is an expansion valve.

The block 11 of the expansion valve 10 is formed with a low-pressure passage 12 for passing a low-temperature and low-pressure refrigerant and a passage 13 for adiabatically expanding a high-temperature and high-pressure refrigerant. The low-pressure passage 12 has one end (inlet side) 12 a connected to the outlet of the evaporator 1, and the other end (outlet side) 12 b connected to the inlet of the compressor 2. One end (inlet side) 13 a of the passage 13 for adiabatically expanding the high-pressure side refrigerant is connected to the outlet of the liquid receiver 4, and the other end (outlet side) 13 b is connected to the inlet of the evaporator 1.

The low-pressure passage 12 and the passage 13 for adiabatic expansion are formed in parallel with each other, and a through hole 14 perpendicular to the passage extends through the two passages 12 and 13. Outside the low-pressure passage 12 (upper side in the figure), a large hole 14a that penetrates outward is formed, and a temperature sensing chamber 30 is attached to the opening.

A valve mechanism 20 is provided from the through hole 14 to the passage 13 for adiabatic expansion. On the other hand, a valve seat 23 is formed at the center of the passage 13 for adiabatic expansion, and when a ball valve 25 urged toward the valve seat 23 from below by a coil spring 24 closes the valve seat 23, The passage 13 for adiabatic expansion is closed.

26 is a ball valve receiver for supporting the ball valve 25. 27 is an adjusting nut which is screwed with the block 11 to adjust the urging force of the coil spring 24. 21 and 22 are O-rings for sealing.

A rod 28 inserted into the through hole 14 is provided so as to be slidable in the axial direction.
0, and the lower end is in contact with the upper end of the ball valve 25.
Therefore, when the ball valve 25 is pushed downward by the rod 28 against the urging force of the coil spring 24 and moved downward, the passage 13 for adiabatic expansion is opened, and the rod 28 is opened.
The passage area of the passage 13 changes in accordance with the amount of movement of the refrigerant, and the amount of refrigerant supplied to the evaporator 1 changes.

The temperature sensing chamber 30 is hermetically surrounded by a housing 31 made of a thick metal plate and a diaphragm 32 made of a flexible thin metal plate (for example, a stainless steel plate having a thickness of 0.1 mm). The passages 12 and 13 are located in the temperature sensing chamber 30.
A gas in a saturated vapor state (e.g., isobutane) or an inert gas (e.g., nitrogen) having the same or similar properties as the refrigerant flowing therein is filled therein.
It is closed by a blind plug 34 made of metal.

Reference numeral 33 denotes a temperature-sensitive chamber mounting seat for mounting the temperature-sensitive chamber 30 to the block 11, and its outer peripheral portion is hermetically welded to the housing 31 and the diaphragm 32 over the entire circumference to form an inner cylindrical portion. Screw part 3
3a is screwed into the block 11. 36 is an O-ring for sealing.

On the surface of the diaphragm 32 on the temperature-sensitive room side,
An adsorbing means 35 for adsorbing the liquid portion when the saturated vapor gas inside condenses and liquefies is added. As the adsorption means 35, for example, a hydrophilic porous synthetic resin may be applied to the inner surface of the diaphragm 32, or water glass may be applied to the inner surface of the diaphragm 32 and fired, such as felt or various fibers. May be adhered to the inner surface of the diaphragm 32.

At the center of the lower surface of the diaphragm 32, a top portion 28a of a rod 28 having a large area is in contact. Therefore, the temperature of the refrigerant flowing in the low-pressure passage 12 is transmitted to the diaphragm 32 via the rod 28 and the temperature-sensitive chamber mounting seat 33.

Therefore, when the temperature of the refrigerant flowing through the low-pressure passage 12 decreases, the temperature of the diaphragm 32 decreases,
Saturated steam gas in the temperature sensing chamber 30 condenses on the inner surface of the diaphragm 32.

Then, since the pressure in the temperature sensing chamber 30 is reduced, the rod 28 is pushed and moved by the coil spring 24, and as a result, the ball valve 25 approaches the valve seat 23 to reduce the flow passage area of the refrigerant. The flow rate of the refrigerant flowing into the evaporator 1 decreases. At this time, the liquid portion of the saturated vapor gas condensed on the inner surface of the diaphragm 32 in the temperature sensing chamber 30 is absorbed by the adsorbing means 3.
5 is adsorbed.

When the temperature of the refrigerant flowing through the low-pressure passage 12 rises, the temperature of the diaphragm 32 rises, so that the liquid portion of the saturated vapor gas that has condensed and adsorbed by the adsorbing means 35 is vaporized again, and The pressure inside rises. Then, the rod 28 is pushed in a direction of separating the ball valve 25 from the valve seat 23, and the flow rate of the refrigerant flowing into the evaporator 1 increases.

On the outer surface of the temperature-sensitive chamber 30, a ring-shaped electric heater 42 which generates heat when energized is closely arranged. A thermistor 43 for detecting the temperature (surface temperature) of the temperature sensing chamber 30 is attached to the outer surface of the blind plug 34 in close contact therewith. Electric heater 42 and thermistor 4
3 is surrounded by a heat insulating material 44.

Then, the detection signal from the thermistor 43 is sent to the control unit 45, and the operation of the drive circuit 46 of the electric heater 42 is controlled by the control signal output from the control unit 45.

A load information signal of the refrigeration cycle is input to the control unit 45, and when there is a sudden change in the load, the heat generation state of the electric heater 42 is controlled in response to the sudden change.
The temperature of the temperature sensing chamber 30 is controlled.

When a variable capacity compressor is used as the compressor 2, the set pressure is input to the control unit, and the temperature of the electric heater 42 is changed according to the pressure, and is sent to the evaporator 1. The flow rate of the refrigerant can also be changed.

FIG. 2 shows the diaphragm 32 in the temperature sensing chamber 30.
FIG. 4 is a characteristic diagram showing a relationship between a surface temperature (that is, a liquid surface temperature of a saturated steam gas) and a pressure. In FIG. 2, is the saturated vapor pressure line of the refrigerant in the refrigeration cycle, is the saturated vapor pressure line of the saturated vapor gas in the temperature sensing chamber 30, and is the temperature sensing chamber 3.
The pressure of the inert gas (non-condensable gas) within 0 is shown.

Therefore, the pressure in the temperature sensing chamber 30 is represented by a curve obtained by summing the pressure of the saturated steam gas and the pressure of the inert gas. The internal pressure changes according to the characteristic diagram, and the opening operation of the expansion valve 10 is controlled.

When the electric heater 42 is energized and the temperature sensing chamber 30 is heated to, for example, 100 ° C., the pressure of the inert gas in the temperature sensing chamber 30 rises as shown by a curve. Then, the pressure in the temperature sensing chamber 30 rises by that amount, and becomes a curve shown by the following curve.

The heating of the temperature-sensitive chamber 30 is quickly performed by energizing the electric heater 42, and the pressure in the temperature-sensitive chamber 30 has a curved characteristic, so that the flow rate of the refrigerant flowing into the evaporator 1 increases. I do.

When the power supply to the electric heater 42 is stopped, the temperature-sensitive chamber 30 is rapidly cooled by the low-temperature heat conduction from the low-pressure refrigerant passing through the low-pressure passage 12, so that the internal pressure immediately changes to the curve characteristic. Returning, the flow rate of the refrigerant flowing into the evaporator 1 decreases.

[0032]

According to the expansion valve of the present invention, the inert gas is filled together with the saturated steam gas in the temperature sensing chamber, and the heater for heating the temperature sensing chamber is provided so as not to come into contact with the diaphragm. Not only can the pressure of the inert gas inside be raised quickly by heating the heater, but also by stopping the operation of the heater, the refrigerant coming out of the evaporator cools the temperature-sensitive chamber, so the gas pressure inside the temperature-sensitive chamber is quickly increased. Can be lowered.

Therefore, the time constant not only at the time of temperature rise but also at the time of temperature drop is small, and the flow rate of the refrigerant sent to the evaporator can always be appropriately controlled, so that the superheat degree of the refrigerant can always be properly maintained. .

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a refrigeration cycle and an expansion valve thereof according to an embodiment.

FIG. 2 is a characteristic diagram of an expansion valve according to an embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Evaporator 10 Expansion valve 30 Temperature sensing chamber 32 Diaphragm 42 Electric heater

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F25B 41/06

Claims (1)

(57) [Claims] A temperature sensing chamber arranged to sense the temperature of a refrigerant flowing out of an evaporator and having a saturated vapor gas sealed therein; and a diaphragm arranged to form one wall surface of the temperature sensing chamber. A valve mechanism driven by the displacement of the diaphragm to change the flow rate of the refrigerant entering the evaporator, wherein an inert gas is sealed together with the saturated steam gas in the temperature-sensitive chamber, and the temperature-sensitive chamber is An expansion valve, wherein a heater for heating is provided at a position where the heater does not contact the diaphragm.