JPH0820138B2 - Refrigeration equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a refrigerating apparatus having a refrigerant circuit in which an economizer is arranged, and more particularly to a measure for improving reliability.

(Prior Art) Conventionally, for example, "Handbook of Refrigeration and Air Conditioning, 4th Edition, Basic Edition,
Page 382, May 30, 1981, Japan Frozen Association
As disclosed in "Issuance", as a refrigerating apparatus including a so-called economizer that increases the refrigerating capacity while suppressing the capacities of the compressor and the condenser, for example, as shown in FIG. In the refrigerant circuit (g) in which the device (b), the liquid receiver (c), the main pressure reducing valve (d), the evaporator (e) and the droplet separator (f) are sequentially connected by the refrigerant pipe, the pressure reducing valve (h ) Gasifies the refrigerant under reduced pressure and bypasses it to a location at an intermediate pressure of the compressor (a) via a bypass path (i), and an intercooler (j) that supercools the liquid refrigerant by its heat of evaporation is installed. What has been received is a known technique. Further, as disclosed in the same document, after decompressing the liquid refrigerant in the liquid pipe, the receiver separates the gas refrigerant and the liquid refrigerant, and the gas refrigerant is bypassed to a location at an intermediate pressure of the compressor to reduce the temperature of the low temperature. There is also known one provided with a so-called economizer receiver in which only the liquid refrigerant is evaporated by the evaporator.

(Problems to be Solved by the Invention) With the above economizer, for example, as shown in the Mollier diagram of FIG. 4, the refrigeration cycle becomes a refrigeration cycle as shown by the solid line in the figure, and as a result, the enthalpy change Δi changes to the economizer. The refrigerating effect is increased by increasing from Δi ₁ when not used to Δi ₂ .

However, for example, in the case where the operating capacity of the compressor is adjusted in multiple stages by an unloader mechanism, the number of times the compressor is stopped is reduced in order to improve the temperature control accuracy of the control target (for example, the liquid temperature in the liquid cooling device). Although it is necessary, if you set the minimum unloader capacity value low and try to reduce the capacity change width between the stopped state,
Since the circulation amount of the refrigerant decreases, there is a possibility that seizure of the compressor may occur due to the retention of the lubricating oil in the refrigerant circuit.

Further, in particular, when an automatic expansion valve having a temperature sensitive tube in the discharge pipe is used as the pressure reducing valve in the economizer, for example, when starting or loading with a compressor with an unloader, an increase in the discharge pressure is immediately detected, but the discharge is increased. Since the rise in the gas temperature is not immediately detected by the temperature sensing cylinder, the automatic expansion valve operates temporarily in the direction to close it, and the discharge gas temperature rises excessively and the lubricating oil deteriorates. There is a risk of damage.

Furthermore, even during normal operation, if conditions such as the cooling load change, the response of the entire system to the change will be delayed due to the provision of the economizer as described above,
There is a possibility that reliability cannot be reduced because the temperature of the discharge pipe cannot be increased quickly.

The present invention has been made in view of the above points, and an object thereof is to improve reliability by providing means for stopping only the function of the economizer without impairing the function of the entire refrigerant circuit. It is in.

(Means for Solving the Problem) In order to achieve the above-mentioned object, the solution means of the present invention includes a path for bypassing a part of the liquid refrigerant to an intermediate pressure part of the compressor, a path through the economizer, and a bypass for the economizer. There is a means to switch to the route to be used.

Specifically, as shown in FIG. 1, the first solution means is a compressor (1) whose operating capacity is adjusted by an unloader mechanism (1a), a condenser (2), and a main decompression mechanism (3). And a main refrigerant circuit (7) in which the evaporator (4) is sequentially connected, and a liquid pipe (5a) between the condenser (2) of the main refrigerant circuit (7) and the main pressure reducing mechanism (3). A first bypass passage (11) for connecting the refrigerant to the intermediate pressure portion of the compressor (1) so as to flow by bypassing the main pressure reducing mechanism (3) and the evaporator (4);
It is premised on a refrigerating apparatus provided with a first pressure reducing mechanism for reducing the pressure of the refrigerant flowing through the first bypass passage (11) and an economizer for increasing the refrigerating capacity based on the pressure reducing effect of the refrigerant by the first pressure reducing mechanism.

The liquid refrigerant in the main refrigerant circuit (7) is supplied to the first
A second bypass passage (14) that bypasses the economizer of the bypass passage (11) and circulates to the location of intermediate pressure of the compressor (1), and a second bypass passage (14) that depressurizes the refrigerant flowing through the second bypass passage (14). A decompression mechanism (16) is provided. Further, a path for bypassing a part of the refrigerant in the liquid pipe (5a) of the main refrigerant circuit (7) to a location having an intermediate pressure of the compressor (1) is provided on the economizer side of the first bypass path (11) and on the second side. A switching means (51) for selectively switching between the two bypass path (14) side is provided. In addition, when the command signal for reducing the capacity is output when the compressor (1) has the minimum capacity, the liquid pipe (5a)
A switching control means (52A) is provided to control the switching means (51) so that a part of the refrigerant therein flows to the second bypass passage (14) side.

A second solution is a main refrigerant circuit (7) in which a compressor (1), a condenser (2), a main decompression mechanism (3) and an evaporator (4) are sequentially connected, and the main refrigerant. When the liquid pipe (5a) between the condenser (2) of the circuit (7) and the main pressure reducing mechanism (3) is at an intermediate pressure of the compressor (1), the refrigerant is evaporated by the main pressure reducing mechanism (3) and evaporated. A first bypass passage (11) for bypassing and connecting the container (4) and a temperature-sensing cylinder (17a) provided in the discharge pipe (5b) of the compressor (1). Automatic expansion valve (1 to reduce the pressure of the refrigerant flowing through the bypass (11)
It is premised on a refrigerating apparatus provided with 7) and an economizer that increases the refrigerating capacity based on the pressure reducing effect of the refrigerant by the automatic expansion valve (17).

Then, while a discharge pipe temperature detecting means (Th1) for detecting the temperature of the discharge pipe (5b) of the compressor (1) is provided,
A second bypass passage (14) for causing the liquid refrigerant of the main refrigerant circuit (7) to flow to a location having an intermediate pressure of the compressor (1) by bypassing the economizer of the first bypass passage (11).
And a pressure reducing mechanism (16) for reducing the pressure of the refrigerant flowing through the second bypass passage (14). Further, a path for bypassing a part of the refrigerant in the liquid pipe (5a) of the main refrigerant circuit (7) to a location having an intermediate pressure of the compressor (1) is provided on the economizer side of the first bypass path (11) and on the second side. A switching means (51) for selectively switching between the two bypass path (14) side is provided.
In addition, receiving the output of the discharge pipe temperature detection means (Th1), when the discharge pipe temperature is equal to or higher than a predetermined set value, the liquid pipe (5
A switching control means (52B) is provided to control the switching means (51) so that a part of the refrigerant in (a) flows to the second bypass passage (14) side.

A second solution is a compressor (1) whose operating capacity is adjusted by an unloader mechanism (1a), a condenser (2),
Between the main refrigerant circuit (7) in which the main pressure reducing mechanism (3) and the evaporator (4) are sequentially connected, and between the condenser (2) and the main pressure reducing mechanism (3) of the main refrigerant circuit (7). A first bypass passage (11) that connects the liquid pipe (5a) to a location at an intermediate pressure of the compressor (1) so that the refrigerant flows by bypassing the main pressure reducing mechanism (3) and the evaporator (4). , An automatic expansion valve (1) having a temperature-sensing cylinder (17a) provided in the discharge pipe (5b) of the compressor (1) and decompressing the refrigerant flowing through the first bypass passage (11).
It is premised on a refrigerating apparatus provided with 7) and an economizer that increases the refrigerating capacity based on the pressure reducing effect of the refrigerant by the automatic expansion valve (17).

The liquid refrigerant in the main refrigerant circuit (7) is supplied to the first
A second bypass passage (14) that bypasses the economizer of the bypass passage (11) and circulates to a location having an intermediate pressure of the compressor (1), and a pressure reducing mechanism that reduces the pressure of the refrigerant flowing through the second bypass passage (14). (16) and are provided. Further, a first route is provided for bypassing a part of the refrigerant in the liquid pipe (5a) of the main refrigerant circuit (7) to a location having an intermediate pressure of the compressor (1).
A switching means (51) for selectively switching between the economizer side of the bypass path (11) and the second bypass path (14) side is provided. In addition, when the capacity of the compressor (1) is changed and a command signal to increase the capacity is output, a part of the refrigerant in the liquid pipe (5a) is partially discharged for a certain period of time in the second bypass passage (14).
A switching control means (52C) for controlling the switching means (51) so as to flow to the side is provided.

A fourth solution means is the above-mentioned first, second or third solution means, wherein the economizer is formed by a part of the liquid pipe (5a) of the main refrigerant circuit (7), and the liquid refrigerant flows therethrough. The inner pipe (9) and the inner pipe (9) interposed in the first bypass passage (11) and provided outside the inner pipe (9) so as to have a predetermined closed cylindrical outer space (10a). A double pipe structure having a pipe (10) is formed, and the gas refrigerant decompressed by the first decompression mechanism is configured to flow through the cylindrical space so as to exchange heat with the liquid refrigerant in the inner pipe (9). And an intercooler (8).

(Operation) With the above configuration, in the invention of claim (1), the switching means (51) causes a part of the liquid refrigerant in the liquid pipe (5a) of the main refrigerant circuit (7) to be the first bypass passage (11). ) Side and is decompressed by the first decompression mechanism and then sucked into the intermediate pressure part of the compressor (1) via the economizer and the economizer of the first bypass passage (11) to bypass the second The bypass path (14) can be selectively switched to a path sucked into the compressor (1), so that the refrigerating capacity can be reduced without reducing the refrigerant circulation amount as necessary, and the capacity adjustment range is expanded. It will be.

Further, when the capacity of the compressor (1) decreases due to the decrease of the load during the operation of the refrigerating apparatus to reach the minimum unloader value, and then the signal of the decrease of the operation capacity due to the decrease of the load is output, the switching control is performed. By means (52A), liquid pipe (5a)
Since the switching means (51) is controlled so that the flow of the liquid refrigerant bypassed from the economizer bypasses the economizer and flows toward the second bypass passage (14), a part of the liquid refrigerant is stopped while the function of the economizer is stopped. As a result of being bypassed to the place where the intermediate pressure of the compressor (1) is reached, the refrigerating capacity is controlled to a capacity equal to or lower than the minimum unloader value without reducing the circulation amount of the refrigerant.

In the invention of claim (2), the discharge pipe temperature detecting means (Th
When the discharge pipe temperature of the compressor (1) detected in 1) becomes equal to or higher than a predetermined set value, the switching control means (52B) causes a part of the refrigerant in the liquid pipe (5a) to cause the second bypass passage (14). Since the switching means (51) is controlled so as to flow to the) side, an excessive rise in the discharge pipe temperature is suppressed by the injection of the refrigerant mixed with the liquid / gas that does not pass through the economizer, and the lubricating oil of the compressor (1) is suppressed. Will be prevented.

In the invention of claim (3), when the command signal for increasing the operating capacity of the compressor (1) is output, the switching control means (52
By C), the switching means (51) is configured so that a part of the refrigerant in the liquid pipe (5a) flows to the second bypass passage (14) side for a certain period of time.
Is controlled, and due to the injection effect of the refrigerant that is a mixture of liquid and gas that does not pass through the economizer, an excessive rise in the discharge pipe temperature at the time of load-up of the compressor (1) with an unloader (1a) is prevented.

In the invention of claim (4), the above claims (1) and (2)
Alternatively, in the invention of (3), in the annular outer space (10a) between the inner pipe (9) and the outer pipe (10), the main refrigerant circuit ( 7)
Since the liquid refrigerant in the liquid pipe (5a) is subcooled, the effect as the economizer in each of the above inventions is exhibited.

(Example) Hereinafter, the Example of this invention is described based on FIGS. 2-9.

FIG. 2 shows an embodiment of the present invention, (1) is a compressor,
(1a) is an unloader mechanism that changes the operating capacity of the compressor (1) to 100, 70, 40, 20 and 0% by suction vane control, (2) is a condenser, and (3) is a main decompression mechanism. External pressure equalizing type automatic expansion valve for evaporator, (4) is an evaporator for cooling the controlled object, (3a) is temperature sensing of the automatic expansion valve (3) arranged on the outlet side of the evaporator (4) A cylinder,
The above-mentioned respective devices (1) to (4) are connected by a refrigerant pipe (5) so that the refrigerant can circulate, and the cold heat obtained in the condenser (2) is moved to the controlled object on the evaporator (4) side. A main refrigerant circuit (7) is constructed.

Here, the liquid pipe (5a) of the refrigerant circuit (7) is provided with an intercooler (8) as an economizer that efficiently increases the refrigerating capacity, and the intercooler (8)
An inner ring (9) forming a part of the liquid pipe (5a) of the main refrigerant circuit (7) and having an inner space (9a) in which the liquid refrigerant flows, and a closed ring between the inner pipe (9) and the inner pipe (9). The outer tube (10a) is sandwiched by the outer tube (10) to form a double tube structure.

Then, the main refrigerant circuit (7) is provided between the liquid pipe (5a) and the intermediate pressure portion of the compressor (1) via the outer space (10a) of the intercooler (8). There is provided a first bypass passage (11) for returning a part of the liquid refrigerant from the automatic expansion valve (3) and the evaporator (4) to the compressor (1). A first opening / closing valve (12) for opening / closing the flow of the refrigerant in the first bypass passage (11) between the intercooler (8) and the liquid pipe (5a) in the bypass passage (11), and the first bypass. A first capillary tube (13) as a pressure reducing mechanism for reducing the pressure of the refrigerant flowing through the passage (11) is provided in order from the liquid pipe (5a) side.

That is, a part of the liquid refrigerant flowing through the liquid pipe (5a) of the main refrigerant circuit (7) is evaporated in the first capillary tube (13) and bypassed to a location at which the compressor (1) has an intermediate pressure, In the cooler (8), the cold heat due to the evaporation supercools the liquid refrigerant flowing in the inner pipe (9).

Further, as a feature of the present invention, in the first bypass passage (11), the refrigerant is bypassed to the intermediate cooler (8) of the first bypass passage (11) to a location where the refrigerant has an intermediate pressure of the compressor (1). A second bypass passage (14) for circulation is provided, and the second bypass passage (14) is provided with a second opening / closing valve (15) for opening and closing the second bypass passage (14) and depressurizing the refrigerant. Second capillary tube (16) as a second pressure reducing mechanism
And are provided in order.

That is, by alternately opening and closing the first and second on-off valves (12) and (15), the first bypass passage (1
The switching means (51) is configured to selectively switch the flow of the refrigerant flowing through the first bypass passage (11) between the intercooler (8) side and the second bypass passage (14) side.

The open / close control of the first and second open / close valves (12) and (15) during the operation of the refrigerating apparatus will be described based on the flowchart of FIG. 3. The intercooler (8) is used in step S1. While performing normal operation, it is determined in step S2 whether or not the operating capacity U of the compressor (1) is the minimum unloader value Umin. If it is the minimum unloader value Umin, the capacity U of the compressor (1) is further determined in step S3. Down signal (below,
U down signal) is input, and if the U down signal is input, it is determined that the refrigerating capacity needs to be reduced without stopping the compressor (1), In step S4, the first on-off valve (12) is closed and the second
The on-off valve (15) is opened to bypass a part of the liquid refrigerant to the second bypass passage (14) side. Then, after the U down signal is released in step S5, the operation returns to the normal operation in step S1.

On the other hand, when the operating capacity U of the compressor (1) is not the minimum unloader value Umin in the determination in step S2, or step
If the U down signal is not output in the determination of S3,
Returning to step S1, normal operation is performed.

In the above flow, in step S4, when the compressor (1) is operated at the minimum capacity and the capacity reduction signal is output, part of the refrigerant in the liquid pipe (5a) is directed to the second bypass passage (14) side. A switching control means (52A) for controlling the switching means (51) so as to flow is configured.

Therefore, according to the invention of claim (1), a part of the liquid refrigerant is depressurized by the first capillary tube (first depressurizing mechanism) (13) to be bypassed to the first bypass passage (11) side, and the economizer (the above-mentioned embodiment is performed). In the example, the intercooler (8) is configured to supercool the liquid refrigerant in the main refrigerant circuit (7), and the refrigerant is compressed by bypassing the economizer in the first bypass passage (11). A second bypass passage (14) for bypassing the intermediate pressure of the switching means (51) is provided.
Thus, the flow of the refrigerant is selectively switched between the economizer side of the first bypass passage (11) and the second bypass passage (14) side, so that the refrigerating capacity can be reduced as necessary.

That is, as shown in the Mollier diagram of FIG. 4 showing changes in the refrigerant state at the points A to G shown in FIG. 2, in the mode using the economizer, the refrigeration cycle is A-B-C-D in the refrigerant circuit (7)
-Cycle changing from EA to the first bypass path (11)
Then, the cycle is changed to (AB-) FGA. That is, the refrigerant is supercooled to BC in the main refrigerant circuit (7) by the amount of enthalpy that changes to FG in the first bypass path (11), and as a result, the refrigerating effect is increased, resulting in an increase in refrigerating capacity. To do.

On the other hand, in the mode in which the flow of the refrigerant bypassed to the compressor (1) is switched to the second bypass path (14) side and the economizer is not used, the refrigeration cycle is A in the main refrigerant circuit (7) as indicated by the broken line in the figure. -B-d-e-A changing cycle, and (AB-) g- on the second bypass path (14) side
The cycle changes to A.

Based on the above, the enthalpy difference Δi ₂ (corresponding to D-E in the figure) in the refrigeration cycle using the economizer and the enthalpy difference Δi ₁ (corresponding to d-e in the figure) in the refrigeration cycle not using the economizer Is reduced by the amount of supercooling (corresponding to B-C), and the refrigerating effect is reduced. That is, the refrigerating capacity can be reduced without changing the capacity of the compressor (1), that is, without reducing the refrigerant circulation amount, and the capacity adjustment range can be expanded.

In addition, when the capacity U of the compressor (1) decreases due to a decrease in load during operation of the refrigeration system to reach the minimum unloader value Umin, and a decrease signal for the operating capacity U due to a further decrease in load is output. The switching control means (52A) controls the switching means (51) so that the flow of the refrigerant that gasifies a part of the liquid refrigerant and bypasses the economizer flows to the second bypass passage (14) side. A part of the liquid refrigerant is bypassed to a place where it has an intermediate pressure of the compressor (1) without contributing to the refrigerating capacity, thereby reducing the refrigerating capacity to the minimum unloader value Umin or less without reducing the refrigerant circulation amount. It can be controlled to the same ability.

In the first embodiment, the bypass paths (11), (1
As a pressure reducing mechanism for 4), the first and second capillary tubes (1
Although 3) and (15) are provided, depending on the conditions, one of them may be used in combination. Needless to say, a three-way valve or the like can be used as the switching means.

Next, FIG. 8 shows a modification of the first embodiment, in which a gas-liquid separator (20) as an economizer is provided in place of the intercooler in the above-mentioned embodiment, and the gas-liquid separator is provided. A capillary tube (21) as a pressure reducing mechanism is provided in the liquid pipe (5a) on the upstream side of (20). A first bypass passage (22) is provided at a location where the intermediate pressure of the compressor (1) is reached from the gas portion of the gas-liquid separator (20), and a refrigerant is provided in the first bypass passage (22). A first on-off valve (23) for controlling the opening and closing of the flow is provided.

In addition, the condenser (2) and the capillary tube (21)
A second bypass passage (24) is provided in a first bypass passage (22) between the liquid pipe (5a) between the first opening and closing valve (23) and the compressor (1), The second bypass passage (24) is provided with a capillary tube (25) as a pressure reducing mechanism and a second opening / closing valve (26) for opening and closing the second bypass passage (24). Other configurations are the same as those in the above-mentioned embodiment.

Then, during normal operation, the first opening / closing valve (23) is opened and the second opening / closing valve (26) is closed to close the liquid pipe (5) of the main refrigerant circuit (7).
By decompressing the refrigerant in a) by the capillary tube (21) and sending only the liquid on the low temperature side to the evaporator (4) by the gas-liquid separator (20), the same economizer effect as that of the above-mentioned embodiment is exhibited. On the other hand, when the compressor (1) is in the lowest unloader state and the command signal for reducing the operating capacity is output, the first opening / closing valve (23) is closed and the second opening / closing valve (26) is opened to open the entire refrigerant. While ensuring the circulation volume, the gas-liquid separator (2
The refrigerating capacity is reduced by stopping the function of separating the liquid refrigerant and the gas refrigerant of 0).

That is, in FIG. 9, as shown by the changes in the refrigerant state corresponding to points P to V in FIG. 8, in the mode in which the economizer is used, the refrigeration cycle is PQ-R as shown by the solid line in the figure. The refrigeration cycle (main refrigerant circuit) changes to -S-T-U-A, and the refrigeration cycle changes to (P-Q-R-) VP. That is, in the gas-liquid separator (20), the refrigerant decompressed by the capillary tube (21) is separated into a gas refrigerant having a high enthalpy (V portion in the figure) and a liquid refrigerant having a low enthalpy (S portion in the figure). By doing
The refrigerating effect of the main refrigerant circuit (7) is increased by an amount corresponding to the enthalpy difference between R and S in the figure.

On the other hand, in the mode in which the economizer is not used, the refrigeration cycle is PQ-R-t-U-, as indicated by the broken line in the figure.
There are cycles that change to A and cycles that change to (P-Q-) WP. That is, since the function of separating the gas refrigerant and the liquid refrigerant of the gas-liquid separator (20) is stopped, the refrigerating effect increasing effect as in the mode using the economizer cannot be obtained, and the refrigerant circulation amount is reduced. Without this, the refrigeration capacity will be reduced.

Therefore, this modification also exhibits the same effect as that of the first embodiment.

Next, a second embodiment according to the inventions of claims (2) and (3) will be described with reference to FIGS.

FIG. 5 shows the structure of the refrigerating apparatus of the second embodiment. In this embodiment, in the first bypass passage (11), the first and second capillary tubes (13), (16) in the first embodiment described above are used.
In place of the above, a bypass automatic expansion valve (17) that also serves as a pressure reducing mechanism in the first and second bypass passages (11) and (14) is provided, and the temperature sensing cylinder (of the bypass automatic expansion valve (17) ( 17
a) is provided in contact with the discharge pipe (5b) of the compressor (1). Further, a discharge pipe sensor (Th1) as a discharge pipe temperature detecting means for detecting the discharge pipe temperature T ₁ is attached to the discharge pipe (5b) of the compressor (1).

 Other configurations are similar to those of the first embodiment.

Here, the content of the control according to the invention of claim (2) will be described based on the flowchart of FIG. 6. While performing the normal operation using the intercooler (8) in step S11, the above-described in step S12. It is determined whether the discharge pipe temperature Tl detected by the discharge pipe sensor (Thl) is equal to or higher than a predetermined set value Tls, and when Tl ≧ Tls, it is determined that the discharge pipe temperature Tl may excessively rise. By shifting to step S13, the first opening / closing valve (12) is closed and the second opening / closing valve (15) is opened to bypass the intercooler (8), whereby the liquid / gas mixed refrigerant is supplied to the compressor (1). By returning, the discharge gas temperature T ₁ is suppressed from rising excessively. Then, in step S14, the discharge pipe temperature Tl becomes lower than a predetermined recovery value Tlr (<Tls), and then the normal operation of step S11 is performed.

In the flow of FIG. 6 above, by step S13,
The switching control means (52B) is configured to control the switching means (51) so that a part of the refrigerant in the liquid pipe (5a) flows to the second bypass passage (14) side when the discharge pipe temperature Tl is equal to or higher than the set value Tls. Has been done.

Therefore, in the invention of claim (2), when the discharge pipe temperature Tl of the compressor (1) detected by the discharge pipe sensor (discharge pipe temperature detection means) (Thl) is equal to or higher than the predetermined set value Tls, the switching control is performed. Since the switching means (51) is controlled by the means (52B) so that a part of the refrigerant in the liquid pipe (5a) flows to the second bypass passage (14) side, it does not pass through the intercooler (8). By injecting a liquid / gas mixed refrigerant,
Excessive rise of the discharge pipe temperature Tl is suppressed, and abnormal stop of the compressor (1) is effectively prevented. Therefore, the reliability can be improved.

On the other hand, FIGS. 7 (i) to (iv) show a time chart of the operation control according to the invention of claim (3), and a start command of the compressor (1) at time t ₁ (see FIG. 7 (i)). When receiving, the unloader (1a) is loaded up to a predetermined stage (see (ii) in the figure). At this time, the first on-off valve (12) remains closed (see (iii) in the same figure) and the second on-off valve (15) remains open (same for the same period of time t ₀ (for example, 1 to 2 minutes)). Figure (i
By referring to v)), the liquid refrigerant is bypassed to a location having an intermediate pressure of the compressor (1), thereby suppressing an excessive rise in discharge gas temperature due to the injection effect of the refrigerant.

After that, the first on-off valve (12) is opened and the second on-off valve (15) is closed (see time t _{2 in} (iii) and (iv) of the same figure) to supercool the liquid refrigerant by the intercooler (8). And continue driving. When the load-up signal is input again and the number of stages of the unloader (1a) is increased ((ii) in the figure)
Time t ₃ reference) in the same manner as described above for a predetermined time t _0, the first on-off valve (12) closed, after injection of the liquid refrigerant by opening the second on-off valve (15), the first on-off valve (12) is opened and the second on-off valve (15) is closed (at time iii) and (iv) at time t.
(See ₄ ) It is designed to drive using a normal economizer (8).

In the time chart of the above control, in the invention of claim (3), the times t _{1 to} t ₂ and t in FIGS. 7 (iii) and (iv) are used.
Under the control of the ₃ ~t _4, when the capacitance change of the compressor (1), the capacity increases when the command signal is output, the liquid pipe (5) second bypass passage between a part fixed time t ₀ of the refrigerant in the Switching control means (52) for controlling the switching means (51) so as to flow to the (14) side
C) is configured.

Therefore, in the invention of claim (3), the compressor (1)
When a command signal to increase the operating capacity of the liquid is output, the switching control means (52C) causes a part of the refrigerant in the liquid pipe (5a) to flow toward the second bypass passage (14) for a certain period of time t _0. The switching means (51) is controlled so as to flow. Where the unloader (1a)
In the case of the attached compressor (1), the discharge pipe temperature Tl may rise excessively at the time of load-up. However, in the present invention, the discharge pipe temperature Tl is controlled so that the refrigerant is injected for a certain period of time. Is prevented from rising excessively, thus
Reliability can be improved.

In the invention of claim (4), the above claims (1) and (2)
Alternatively, in the invention of (3), the economizer has a structure in which an inner pipe (9) formed of a part of the liquid pipe (5a) and a closed annular outer space (10a) are provided between the inner pipe (9). And a double tube structure consisting of the outer tube (10),
Since the gas refrigerant decompressed by the decompression mechanism is made to flow into the outer space (10a) to supercool the liquid refrigerant, the effect as the economizer in each of the above inventions can be effectively exhibited.

Needless to say, an economizer of the type using a gas-liquid separator (20) as shown in FIG. 8 can also be applied to the inventions of claims (2) and (3).

In the second embodiment, the bypass automatic expansion valve (17)
Therefore, the first and second decompression mechanism are also used.
The second pressure reducing mechanism may be separately provided.

(Effect of the invention) As described above, according to the invention of claim (1),
In a refrigerating apparatus including an economizer that increases a refrigerating capacity based on a depressurizing effect of refrigerant sucked into the compressor from the first bypass path, a second bypass path that bypasses the economizer and sucks the liquid refrigerant into the compressor is provided. Since a part of the liquid refrigerant in the liquid pipe is selectively switched between the first bypass path side and the second bypass path side, use or non-use of the economizer can be selected according to the operating state of the device. Therefore, the adjustment range of the refrigerating capacity can be expanded without reducing the refrigerant circulation amount.

Further, when the capacity of the compressor is the minimum capacity and the capacity reduction command signal of the compressor is output, the bypass refrigerant is controlled to flow to the second bypass passage side, so that the refrigerant flow rate is reduced. Therefore, the refrigerating capacity can be reduced without increasing the reliability of the temperature control without lowering the reliability.

Further, according to the invention of claim (2), the adjustment range of the refrigerating capacity can be expanded, and when the discharge pipe temperature is equal to or higher than a set value, a part of the liquid refrigerant in the liquid pipe is second.
Since the flow is controlled so as to flow to the bypass path side, it is possible to effectively suppress the excessive rise in the discharge pipe temperature due to the liquid refrigerant, and thus to improve the reliability.

According to the invention of claim (3), it is possible to expand the adjustment range of the refrigerating capacity, and at the time of increasing the capacity of the compressor, a part of the refrigerant in the liquid pipe remains on the second bypass path side for a certain period of time. Since the flow is controlled so as to flow, it is possible to prevent the temperature of the discharge pipe from excessively rising due to the injection effect of the liquid / gas mixed refrigerant, and thus to improve the reliability.

According to the invention of claim (4), the above-mentioned claim (1),
In the invention of (2) or (3), the economizer is a double pipe including an inner pipe formed by a part of the liquid pipe of the main refrigerant circuit and an outer pipe provided outside the inner pipe. Since the intercooler has a structure and is configured to supercool the liquid refrigerant in the liquid pipe with the gas refrigerant flowing through the first bypass passage,
The ability increasing effect in each of the above inventions can be effectively exerted, and thus each invention can be put into effect.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention. 2 to 4 show the first embodiment, FIG. 2 is a refrigerant piping system diagram showing the overall configuration of the refrigerating apparatus, FIG. 3 is a flow chart diagram showing the control content, and FIG. 4 is the effect of the invention. 5 to 7 show a second embodiment, FIG. 5 is a refrigerant piping system diagram of the refrigerating apparatus, and FIG. 6 is a flow chart showing the control contents of the invention of claim (2). FIG. 7 is a time chart showing the control contents of the invention of claim (3), and FIG.
FIGS. 9 and 10 show a modification of the first embodiment, FIG. 8 is a refrigerant piping system diagram, and FIG. 9 is a Mollier diagram showing a refrigeration cycle. FIG. 10 is a refrigerant piping system diagram showing a configuration example of a conventional refrigerating apparatus in which an economizer is arranged. 1 ... Compressor 1a ... Unloader 2 ... Condenser 3 ... Automatic expansion valve (main decompression mechanism) 4 ... Evaporator 5a ... Liquid pipe 7 ... Main refrigerant circuit 8 ... Intermediate cooler (economizer) 9 …… Inner tube 10 …… Outer tube 11 …… First bypass path 13 …… First capillary tube (pressure reducing mechanism) 14 …… Second bypass path 16 …… Second capillary tube (pressure reducing mechanism) 17 …… Bypass Automatic expansion valve (decompression mechanism) 17a …… Temperature sensing cylinder 51 …… Switching means 52 …… Switching control means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Arai 1304 Kanaoka-machi, Sakai City, Osaka Prefecture Daikin Industries, Ltd. Kanaoka Plant, Sakai Manufacturing Co., Ltd. (56) Reference JP-A-62-19654 (JP, A) JP-A-SHO 62-106252 (JP, A)

Claims (4)

[Claims] 1. A main refrigerant circuit in which a compressor (1) whose operating capacity is adjusted by an unloader mechanism (1a), a condenser (2), a main pressure reducing mechanism (3) and an evaporator (4) are sequentially connected. (7), the condenser (2) of the main refrigerant circuit (7) and the main decompression mechanism (3)
A first bypass passage connecting a liquid pipe (5a) between the refrigerant pipe and the refrigerant pipe to a place having an intermediate pressure of the compressor (1) so that the refrigerant flows by bypassing the main pressure reducing mechanism (3) and the evaporator (4). (11)
A first depressurizing mechanism for depressurizing the refrigerant flowing through the first bypass passage (11); and an economizer for increasing refrigerating capacity based on the depressurizing effect of the refrigerant by the first depressurizing mechanism. A second bypass passage (14) for circulating the liquid refrigerant of the refrigerant circuit (7) to a location having an intermediate pressure of the compressor (1) by bypassing the economizer of the first bypass passage (11); A second pressure reducing mechanism (16) for reducing the pressure of the refrigerant flowing through the bypass passage (14) and part of the refrigerant in the liquid pipe (5a) of the main refrigerant circuit (7) becomes the intermediate pressure of the compressor (1). Switching means (51) for selectively switching the bypass route to the economizer side of the first bypass route (11) and the second bypass route (14) side, and the capacity at the minimum capacity of the compressor (1). When the command signal to be reduced is output, the cooling in the liquid pipe (5a) Refrigeration system, wherein a part is provided with a switching control means for controlling the switching means (51) to flow into the second bypass passage (14) side (52A) of the. 2. A main refrigerant circuit (7) in which a compressor (1), a condenser (2), a main pressure reducing mechanism (3) and an evaporator (4) are sequentially connected, and the main refrigerant circuit (7). Condenser (2) and main decompression mechanism (3)
A first bypass passage connecting a liquid pipe (5a) between the refrigerant pipe and the refrigerant pipe to a place having an intermediate pressure of the compressor (1) so that the refrigerant flows by bypassing the main pressure reducing mechanism (3) and the evaporator (4). (11)
An automatic expansion valve (17) having a temperature-sensing cylinder (17a) provided in the discharge pipe (5b) of the compressor (1) to reduce the pressure of the refrigerant flowing through the first bypass passage (11); In a refrigerating apparatus equipped with an economizer that increases refrigerating capacity based on the refrigerant decompressing effect of an automatic expansion valve (17), a discharge pipe temperature detecting means (for detecting the temperature of the discharge pipe (5b) of the compressor (1) ( Th1) and the liquid refrigerant of the main refrigerant circuit (7) are circulated to the location of intermediate pressure of the compressor (1) by bypassing the economizer of the first bypass path (11). ), A pressure reducing mechanism (16) for reducing the pressure of the refrigerant flowing through the second bypass passage (14), and a part of the refrigerant in the liquid pipe (5a) of the main refrigerant circuit (7) of the compressor (1). The bypass path to the intermediate pressure location is the economizer side of the first bypass path (11) and the second bypass path. When the discharge pipe temperature is equal to or higher than a predetermined set value by receiving the output of the switching device (51) for selectively switching to the passage (14) side and the discharge pipe temperature detecting device (Th1), the liquid pipe (5a) And a switching control means (52B) for controlling the switching means (51) so that a part of the refrigerant flows to the second bypass passage (14) side. 3. A main refrigerant circuit in which a compressor (1) whose operating capacity is adjusted by an unloader mechanism (1a), a condenser (2), a main decompression mechanism (3) and an evaporator (4) are sequentially connected. (7), the condenser (2) of the main refrigerant circuit (7) and the main decompression mechanism (3)
A first bypass passage connecting a liquid pipe (5a) between the refrigerant pipe and the refrigerant pipe to a place having an intermediate pressure of the compressor (1) so that the refrigerant flows by bypassing the main pressure reducing mechanism (3) and the evaporator (4). (11)
An automatic expansion valve (17) having a temperature-sensing cylinder (17a) provided in the discharge pipe (5b) of the compressor (1) to reduce the pressure of the refrigerant flowing through the first bypass passage (11); In a refrigerating apparatus provided with an economizer that increases the refrigerating capacity based on the refrigerant decompressing effect of the automatic expansion valve (17), the liquid refrigerant of the main refrigerant circuit (7) is supplied to the economizer of the first bypass path (11). A second bypass passage (14) which is bypassed and circulates to a location having an intermediate pressure of the compressor (1), a pressure reducing mechanism (16) for reducing the pressure of the refrigerant flowing through the second bypass passage (14), and the main refrigerant. A path for bypassing a part of the refrigerant in the liquid pipe (5a) of the circuit (7) to a location having an intermediate pressure of the compressor (1) is provided on the economizer side of the first bypass path (11) and the second bypass path (14). ) Side, and a capacity change of the compressor (1) , A switching control means for controlling the switching means (51) so that a part of the refrigerant in the liquid pipe (5a) flows to the second bypass passage (14) side for a certain period of time when a command signal for increasing the capacity is output. (52C) and the refrigerating device. 4. The economizer is formed by a part of the liquid pipe (5a) of the main refrigerant circuit (7), and the inner pipe (9) through which the liquid refrigerant flows.
And an outer pipe (10) provided in the first bypass passage (11) and provided outside the inner pipe (9) so as to have a predetermined closed cylindrical outer space (10a). And an intermediate cooler configured such that the gas refrigerant decompressed by the first decompression mechanism flows through the cylindrical space so as to exchange heat with the liquid refrigerant in the inner pipe (9). It is 8), The freezing apparatus of Claim (1), (2), or (3) characterized by the above-mentioned.