JPH0854148A - Refrigerating device - Google Patents

Abstract

PURPOSE:To expand the range of operation while improving the reliability of a refrigerating device by a method wherein the pilot pressure of a temperature sensitive expansion valve for liquid injection is controlled to reduce the superheating degree of discharged gas and secure the cooling of a compressor sufficiently, in an operation area wherein the discharged gas becomes high- pressure and high-temperature gas. CONSTITUTION:When the pressure of discharged gas or a pilot pressure taken into a pilot passage 72 has exceeded a set value, a pressure regulating valve 80 is opened and the pilot pressure is released to the side of low pressure through a communicating line 9 to increase the opening degree of the temperature sensitive expansion valve 7 while the amount of liquid injection is increased to reduce the degree of superheat of discharged gas whereby the increase of the temperature of discharged gas is restrained and the cooling of a compressor 1 can be secured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is designed to inject a liquid such as a high-pressure liquid refrigerant or a high-pressure oil into an intermediate pressure chamber in the middle of compression in a compressor to control the degree of superheat of discharge gas within an appropriate range. Refrigeration equipment.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4 of Japanese Patent Publication No. 63-25255 and shown in FIG. 4, a screw type compressor S having a screw rotor R is provided with an injection port M opening to an intermediate pressure chamber during compression. A liquid injection passage J extending from a high-pressure liquid region H between the condenser C and the pressure reducing mechanism W is connected to the injection port M, and a circulating refrigerant (for example, Freon 22) is connected to the passage J.
On the other hand, under the same pressure condition, a refrigerant having a high saturation temperature (for example, Freon 12) is enclosed inside, and a temperature sensing tube T that senses the discharge gas temperature of the compressor S, and a pilot that takes in the discharge gas pressure of the compressor S A temperature-sensitive expansion valve V having a passage P is interposed. In this way, the difference in saturation temperature between the freon 22 and the freon 12 (about 20 deg) is added to the normal superheat control value of 5 to 10 deg determined by the set spring force of the temperature expansion valve V, and the superheat of the discharge gas is set to 25. It is controlled to a predetermined value of about 30 deg. In addition, in FIG. 4, E is an evaporator.

[0003]

The degree of superheat of the discharge gas is
The point that seizure caused by the difference in thermal expansion between the movable member side such as the screw rotor R and the stationary member side such as the casing that covers the outer periphery thereof should be prevented, and the lubricating performance by the lubricating oil should be ensured. Both sides must be controlled to proper values.

That is, since it is necessary to prevent leakage in the compression chamber defined by the movable member and the stationary member, the seal gap between both members is controlled to be small, and when a difference in thermal expansion appears between the two members, A gap occurs in the gap. In general, a movable member inside is easily heated to a temperature higher than that of an outer stationary member that is easily cooled by the outside air, and a large thermal expansion of the movable member causes an outer surface of the movable member to collide with an inner surface of the stationary member. Therefore, liquid refrigerant or oil is injected into the intermediate pressure chamber during compression to cool the movable member, and the degree of superheat of the discharged gas is suppressed below a certain level,
It is necessary to lower the discharge gas temperature. On the other hand, if the superheat degree of the discharge gas is made too small, a large amount of the refrigerant dissolves in the oil flowing out to the discharge side together with the gas, the viscosity of the oil decreases, the oil droplets become finer, and oil separation becomes difficult. , The lubrication performance may decrease. Therefore, the degree of superheat of the discharged gas does not have to be too large or too small, and is preferably about 25 deg.

In the above conventional example, the CFC 22 and CFC 12 are
Is added to the normal superheat control value of the temperature-sensitive expansion valve V to control the superheat of the discharge gas to a predetermined value of about 25 to 30 deg. At first glance, it seems to satisfy both sides of securing.

However, in practice, as shown in FIG. 3, the circulating refrigerant (CFC 22) taken into the pilot passage.
The saturation temperature difference between the refrigerant and the refrigerant (Freon 12) sealed in the temperature sensing cylinder does not always show a constant value in a wide operating range, and the temperature difference tends to increase as the pressure increases, and The higher the pressure of the discharged gas becomes and the larger the temperature difference from the outside air becomes, the more the heat radiation amount of the temperature sensing tube itself or its mounting portion increases, and the temperature actually sensed by the temperature sensing tube becomes lower. Therefore, due to the deviation of the saturation temperature difference between these circulating refrigerant and the temperature-sensing cylinder-enclosed refrigerant and the effect of heat radiation of the temperature-sensing cylinder, in the operating region where the discharge gas has a high pressure and high temperature, the degree of superheat becomes unnecessarily large, There is a problem that the compressor is not sufficiently cooled, its reliability is lowered, and a wide operating range cannot be covered. In particular, this problem becomes remarkable in a hot water chiller system having a discharge pressure range wider than that of a general air conditioning system.

The main object of the present invention is to ensure sufficient cooling of the compressor in an operating region where the discharge gas has a high pressure and high temperature, and to perform appropriate superheat control within a wide operating range, thereby improving the reliability of the compressor. It is a point to provide a refrigeration system capable of improving the operation range while improving.

[0008]

In order to achieve the above-mentioned main object, the invention according to claim 1 is, as shown in FIG. 1, an injection port opening to an intermediate pressure chamber in the middle of compression in a compressor 1. 16, a liquid injection passage 6 extending from a high pressure region is connected to the injection port 16, and a refrigerant having a high saturation temperature is filled in the passage 6 under the same pressure condition with respect to the circulating refrigerant. A refrigeration system having a temperature sensitive cylinder 71 for sensing the discharge gas temperature and a pilot passage 72 for taking in the discharge gas pressure of the compressor 1 and having a temperature sensitive expansion valve 7 for controlling the superheat degree of the discharge gas to a predetermined value. In the pilot passage 72, when the pressure or temperature of the discharge gas exceeds a set value, the pilot passage 72 is opened to a low pressure region of low pressure with respect to a high pressure region, The pilots pressure provided pressure adjusting means 8 for releasing the low pressure side.

According to the second aspect of the present invention, since the pressure adjusting means 8 is simply constructed, as shown in FIG. 2, the pressure adjusting means 8 is interposed in the communication line 9 for opening the pilot passage 72 in the low pressure region. The valve body 81 is operated by the pilot pressure in the pilot passage 72 to open and close the passage 72 with respect to the low pressure region.
And a biasing body 82 for setting the operating pressure of the valve body 81.

[0010]

In the invention described in claim 1, as shown in FIG.
When the pressure or temperature of the discharge gas exceeds the set value in the operating region where the discharge gas has a high pressure and high temperature, the pressure adjusting means 8 opens the pilot passage 72 of the temperature-sensitive expansion valve 7 to the low pressure region, The pilot pressure in the pilot passage 72 is released to the low pressure side. Thereby, in the temperature-sensitive expansion valve 7,
Due to the pressure from the temperature sensitive cylinder 71 side, the opening degree is increased, and the amount of liquid transferred to the liquid injection passage 6 is increased,
The amount of liquid injected into the intermediate pressure chamber of the compressor 1 via the injection port 16 increases. For this reason, as shown in FIG. 3, the degree of superheat of the discharge gas is reduced, the temperature rise of the discharge gas can be suppressed, and the cooling of the compressor 1 can be ensured.

On the other hand, even if the superheat degree of the discharge gas is reduced in this way, under the high-pressure and high-temperature conditions of the discharge gas in which the superheat degree is reduced, the air volume of the discharge gas itself is small, so the oil in the discharge passage is small. There is a sufficient margin in separation capacity, and deterioration of oil separation efficiency due to a decrease in superheat does not pose a problem. Also from the aspect of refueling, under the high pressure and high temperature conditions of the discharge gas where the degree of superheat becomes small, a high and low differential pressure can be sufficiently secured, a large oil transfer force can be secured, and a sufficient amount of refueling can be secured, By sufficiently reducing the pressure in the oil transfer route to the oil supply point, the refrigerant dissolved in the oil can be evaporated and the viscosity of the oil can be maintained.

In this way, in the operating region where the discharged gas has a high pressure and a high temperature, it is possible to sufficiently secure the cooling of the compressor 1, maintain a high lubricating performance, and improve the reliability of the compressor 1.

According to the second aspect of the present invention, as shown in FIG. 2, the pressure of the discharge gas, that is, the pilot pressure taken into the pilot passage 72, in the operating region where the discharge gas has a high pressure and a high temperature, is due to the urging body 82. When the set pressure is exceeded, the valve element 81 operates to open the communication line 9 and open the pilot passage 72 in the low pressure region. As a result, the opening degree of the temperature-sensitive expansion valve 7 is increased, and the liquid injection passage 6
Therefore, the amount of liquid injected into the intermediate pressure chamber of the compressor 1 increases, the degree of superheat of the discharge gas decreases, the temperature rise of the discharge gas can be suppressed, and the cooling of the compressor 1 can be ensured.

As described above, by detecting the self-pressure by the pressure control valve 80 having the valve body 81 and the biasing body 82, the injection liquid amount is automatically increased in the operating region where the discharge gas has a high pressure and a high temperature, and the superheat is generated. Since the frequency is reduced, the structure can be simplified accordingly.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 1 is a screw type compressor having a screw rotor 12 inside a casing 11, and a low pressure suction gas refrigerant sucked from a suction port 13 is provided in a screw groove 14 of the screw rotor 12.
Is compressed inside, and high-pressure discharge gas is discharged from the discharge port 15. An injection port 16 that opens to the intermediate pressure chamber in the middle of compression is provided after the closed portion of the suction gas in the screw groove 14.
Although the single type shown in the drawing has one screw rotor 12, it may be a double type having a pair of screw rotors. Further, the type of the compressor 1 is not limited to the screw type, but may be a scroll type or the like.

From the discharge side to the suction side of the compressor 1,
A condenser 2 that condenses the high-pressure discharge gas into a high-pressure liquid, a receiver 20 that stores the condensed high-pressure liquid, a decompression mechanism 3 that decompresses the high-pressure liquid refrigerant into a low-pressure liquid, and a low-pressure liquid that evaporates to a low pressure. The evaporator 4 used as a gas is sequentially connected via a high pressure gas pipe 51, high pressure liquid pipes 52 and 53, a low pressure liquid pipe 54, and a low pressure gas pipe 55 to form a refrigeration cycle. Freon 22 is used as the circulating refrigerant.

The injection port 16 has a liquid injection passage 6 formed of a pipe extending from the liquid receiver 20.
In this passage 6, a freon 12 which is a refrigerant having a high saturation temperature under the same pressure condition as the circulating refrigerant is sealed inside, and a temperature sensing tube 7 for sensing the temperature of the gas discharged from the compressor 1 is connected.
1 and a pilot passage 72 composed of a small-diameter pipe for taking in the discharge gas pressure of the compressor 1, and a temperature-sensitive expansion valve 7 for controlling the superheat degree of the discharge gas to a predetermined value is interposed. As is known, the temperature-sensitive expansion valve 7 causes the pressure of the temperature-sensitive cylinder 71 and the added value of the pilot pressure of the pilot passage 72 and the spring force of the setting spring 73 to oppose each other via the diaphragm 74, so that the diaphragm 74 receives the valve. The valve body 76 directly connected via the rod 75 is operated to open and close the passage 6.

In the above structure, the pilot passage 72
When the pressure or temperature of the discharge gas exceeds the set value, the pilot passage 72 is opened to the suction port 13 of the compressor 1 which is a low pressure region where the pressure is higher than the high pressure region, and the pilot pressure is released to the low pressure side. Means 8 are provided.

Specifically, the pressure adjusting means 8 is provided in a communication line 9 formed of a pipe branched from an intermediate portion of the pilot passage 72 and connected to the suction port 13.
It consists of zero.

Pressure regulating valve 80 constituting the pressure regulating means 8
2 operates inside the main body 800 by the pilot pressure of the pilot passage 72 taken from the primary side 91 of the communication line 9 to open / close the primary side 91 with respect to the secondary side 92 on the low pressure side. Ball type valve body 81 and this valve body 8
When the pilot pressure exceeds the pressure set by the biasing body 82, the valve body 81 is separated from the valve seat 83, and the communication line 9 of the communication line 9 is provided. The primary side 91 and the secondary side 92 are communicated with each other, and the pilot pressure in the pilot passage 72 is released to the low pressure side. In FIG. 2, 84 is a biasing member 82.
Reference numeral 85 is a screw-in type adjusting body for adjusting the setting pressure, 85 is a connecting rod for connecting the urging body 82 side and the valve body 81 side, and 86 is a bellows for stabilizing the operation of the valve body 81.

With the above-described structure, the discharge gas is in an operating region where the discharge gas has a high pressure and a high temperature, and the pressure of the discharge gas, that is, the pilot pressure taken into the pilot passage 72 is the biasing member 8.
When the pressure set by 2 is exceeded, the valve body 81 is automatically opened, the communication line 9 is opened, and the pilot passage 72 is opened to the low pressure region. As a result, the opening degree of the temperature-sensitive expansion valve 7 increases, the amount of liquid injected from the liquid injection passage 6 into the intermediate pressure chamber of the compressor 1 increases, the superheat of the discharge gas decreases, and the temperature of the discharge gas rises. That is, the cooling of the compressor 1 can be ensured.

[0022]

According to the first aspect of the present invention, the pilot pressure of the temperature-sensitive expansion valve 7 that determines the amount of injection liquid to the compressor 1 is controlled in the operating region where the discharge gas has a high pressure and high temperature, and To increase the injection liquid volume,
The degree of superheat of the discharge gas can be reduced, cooling of the compressor 1 can be sufficiently ensured, and high lubrication performance can be maintained.
The operating range can be expanded while improving the reliability of the.

According to the second aspect of the present invention, the self-pressure sensing by the pressure control valve 80 automatically increases the injection liquid amount and lowers the superheat degree in the operating region where the discharge gas has a high pressure and high temperature. , The configuration can be simplified.

[Brief description of drawings]

FIG. 1 is a piping diagram of a refrigerating apparatus according to the present invention.

FIG. 2 is a cross-sectional view of a pressure control valve used in the refrigeration system.

FIG. 3 is a temperature vs. pressure characteristic diagram showing the effect of the refrigeration system in comparison with a conventional example.

FIG. 4 is a piping diagram of a conventional example.

[Explanation of symbols]

1; compressor, 16; injection port, 6; liquid injection passage, 7; temperature-sensitive expansion valve, 71; temperature-sensitive cylinder,
72; pilot passage, 8; pressure adjusting means, 80; pressure adjusting valve, 81; valve body, 82; biasing body, 9; communication line

Claims (2)

[Claims] 1. A compressor (1) is provided with an injection port (16) opening to an intermediate pressure chamber during compression, and a liquid injection passage (6) extending from a high pressure region is connected to this injection port (16). Then, the passage (6) is filled with a refrigerant having a high saturation temperature under the same pressure condition with respect to the circulating refrigerant, and the temperature sensing cylinder (71) for sensing the discharge gas temperature of the compressor (1) and the compressor ( In a refrigerating apparatus having a pilot passage (72) for taking in the discharge gas pressure of 1) and having a temperature-sensitive expansion valve (7) for controlling the superheat degree of the discharge gas to a predetermined value, the pilot passage (72) is provided. When the pressure or temperature of the discharge gas exceeds a set value, the pilot passage (72) is opened to a low pressure region which is lower than the high pressure region, and the pilot pressure of the pilot passage (72) is released to the low pressure side. Refrigeration system, characterized in that a stage (8). 2. A pressure adjusting means (8) is interposed in a communication line (9) for opening a pilot passage (72) to a low pressure region,
A valve body (81) that operates by pilot pressure in the pilot passage (72) to open and close the passage (72) with respect to a low pressure region;
A biasing body (82) for setting the operating pressure of this valve body (81)
2. Refrigeration system according to claim 1, comprising a pressure regulating valve (80) with and.