JPH10232076A - Refrigerating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the rate of change in an evaporating temperature with respect to the flow rate regulating amount in a pressure loss means by a method wherein hot gas is bypassed to the upstream side of the pressure loss means such as a proportional control valve or the like. SOLUTION: Upon cooling operation, high-pressure gas refrigerant is supplied to the upstream side of a proportional control valve 35 by opening the solenoid valve SV-3 of a hot gas bypass pipe 36 to sent a part of discharging refrigerant of a compressor 11. According to such an operation, the refrigerant flows through the proportional control valve 35 under a condition that refrigerant, evaporated in a heat exchanger 22 in a refrigerator, is mixed into the high- pressure gas refrigerant. Accordingly, the amount of refrigerant, which flows through the proportional control valve 35, can be increased and, therefore, the change of flow rate is increased even when a proportional control valve 35 is choked slightly whereby the evaporating temperature of the heat exchanger 22 in the refrigerator can be reduced remarkably. According to this method, the changing rate of the evaporating temperature of the heat exchanger 22 in the refrigerator with respect to the changing amount of opening degree of the proportional control valve 35 can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a refrigeration system,
In particular, the present invention relates to an improvement in which a pressure reducing means such as a proportional control valve is provided on the suction side of a compressor, and the evaporator capacity is adjusted by controlling the pressure reducing means.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Application Laid-Open No. 2-71076
There is known a refrigerating apparatus used for a freezer or the like as disclosed in Japanese Patent Application Laid-Open Publication No. H11-209,878. This type of refrigeration system
The compressor and the condenser housed in the outside unit, the expansion valve and the evaporator housed in the inside unit are connected in order by refrigerant piping. During operation, the gas refrigerant discharged from the compressor is condensed by exchanging heat with the outside air in the condenser, then decompressed by the expansion mechanism, and is evaporated by exchanging heat with the air in the refrigerator by the evaporator. Thereby, the inside air is cooled to a predetermined temperature. The degree of pressure reduction of the expansion mechanism is adjusted so that the degree of superheat of the refrigerant at the evaporator outlet side is constant.

In general, in this type of refrigeration system, the compressor is switched on and off in accordance with the suction temperature of a unit in the refrigerator in order to maintain the temperature in the refrigerator at a predetermined temperature. However, in this case, since the internal temperature of the refrigerator is changed by turning on and off the compressor, it is not suitable for a case in which high-precision internal temperature control is required.

For this reason, a proportional control valve whose opening can be adjusted is provided on the suction side of the compressor, and the proportional control valve is controlled in accordance with the suction temperature of the in-compartment unit while the compressor is constantly driven. Adjusting the refrigeration capacity has also been performed. That is, when the opening of the proportional control valve is reduced, a pressure loss occurs in the compressor suction side pipe, and the evaporation temperature increases by the pressure loss, thereby reducing the evaporator capacity. Therefore, by adjusting the opening of the proportional control valve so that the suction temperature is maintained at the predetermined temperature, it is possible to perform highly accurate internal temperature control.

[0005]

In the refrigerating apparatus using the above-described proportional control valve, the suction side of the compressor is reduced by the proportional control valve. As a result, the refrigerant circulation amount decreases as a whole. With this, the superheat degree of the refrigerant at the evaporator outlet side increases, and the expansion valve performing the superheat degree constant control,
Its opening increases. As the degree of opening increases, more refrigerant flows into the evaporator, and the evaporating capacity increases.
As described above, since the opening of the proportional control valve is controlled in accordance with the suction temperature of the in-compartment unit, the suction temperature decreases as the evaporation capacity increases, and therefore, the opening of the proportional control valve further decreases. Become smaller. By repeating such an operation, the opening of the proportional control valve becomes extremely small. As described above, in the conventional configuration, it is difficult to secure a large capacity control range of the proportional control valve. Further, since the compression ratio increases with a decrease in the suction pressure of the compressor, there has been another problem that the discharge pipe temperature is excessively increased.

[0006] The present invention has been made in view of the above point, and the capacity control range of the proportional control valve is expanded as compared with the case where the capacity of the evaporator is adjusted by the proportional control valve provided on the suction side of the compressor. And to prevent the discharge pipe temperature of the compressor from excessively rising.

[0007]

In order to achieve the above object, the present invention increases the flow rate at a pressure loss means by bypassing hot gas upstream of the pressure loss means such as a proportional control valve. In this case, the change rate of the evaporation temperature with respect to the change amount of the flow rate adjustment by the pressure loss means is increased. That is, it is possible to greatly change the evaporation temperature even with a small change in the flow rate.

[0008] Specifically, the invention according to claim 1 is a compressor.
(11), a condenser (13), an expansion mechanism (21), and a refrigerant circuit (30) in which an evaporator (22) is connected in order so that the refrigerant can circulate, and the compressor (11) On the suction side, an evaporator is produced by causing a pressure loss on the suction side and adjusting the pressure loss.
It is assumed that the refrigerating apparatus is provided with a pressure loss means (35) for making the evaporation temperature variable in (22). Hot gas supply means (3) for supplying a part of the refrigerant discharged from the compressor (11) to the upstream side of the pressure loss means (35).
6) is provided.

According to this particular matter, the pressure drop means (35)
The refrigerant evaporated in the evaporator (22) and the high-pressure gas refrigerant from the hot gas supply means (36) are mixed and flow through the pressure loss means (35). That is, since the flow rate of the refrigerant flowing through the pressure loss means (35) can be increased, the flow rate change amount when the pressure loss is generated in the pressure loss means (35) with respect to the total flow rate in a state where no pressure loss is generated. Even if the ratio is small, the pressure loss can be increased. That is, since the degree of pressure reduction on the upstream side of the pressure loss means (35) is proportional to the square of the actual flow rate change amount in the pressure loss means (35), the evaporation temperature of the evaporator (22) with respect to the flow rate ratio is determined. The rate of change can be increased, and the control range of the evaporation temperature of the evaporator (22) by the pressure loss means (35) can be expanded. Also, since the suction pressure of the compressor (11) can be increased, as in the prior art,
It is also possible to avoid a situation where the discharge pipe temperature rises excessively with an increase in the compression ratio.

[0010] The invention according to claims 2 and 3 embodies the equipment constituting the refrigeration apparatus. First, claim 2
In the described invention, the pressure loss means is a proportional control valve (35) whose opening is freely adjustable.

According to this specific matter, since the flow rate of the refrigerant flowing through the proportional control valve (35) is increased by the hot gas, the flow rate change is large even if the proportional control valve (35) is slightly reduced. As a result, the amount of change in the pressure loss increases accordingly, and the evaporation temperature of the evaporator (22) can be significantly reduced. In other words, the evaporator is operated by changing the opening of the proportional control valve (35).
(22) The control range of the evaporation temperature can be expanded.

According to the third aspect of the present invention, the expansion mechanism is an external pressure equalizing type temperature-sensitive expansion valve (21).

In this particular case, particularly when the external pressure equalizing type temperature-sensitive expansion valve (21) is employed, the degree of superheat of the refrigerant at the evaporator outlet side increases when the refrigerant circulation amount decreases as a whole circuit. As a result, the valve opening increases and the pressure loss means (35)
However, according to the present invention, as described above, the increase in the pressure loss can be suppressed and the control range of the evaporation temperature can be expanded.

According to the present invention, the injection circuit (20) supplies a part of the liquid refrigerant condensed in the condenser (13) to the suction side of the compressor (11) and to the downstream side of the pressure loss means (35). ), The injection circuit (20), the compressor (11)
Control valve (SV-1,
SV-2).

There is a possibility that the degree of superheat of the gas discharged from the compressor (11) may be excessively increased by bypassing the high-pressure gas refrigerant from the hot gas supply means (36). By supplying the liquid refrigerant to the suction side of the machine (11), the degree of superheat of the discharged gas refrigerant can be appropriately adjusted.

[0016]

Next, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the refrigeration apparatus (10) according to the present embodiment cools a refrigerator or a freezer, and includes an external unit (1A) and an internal unit (1B).

The external unit (1A) is provided with a scroll type compressor (11) and a four-way switching valve (12) which switches as shown by a solid line in the drawing during a cooling operation inside the refrigerator and as shown by a broken line in the defrosting operation. ), An outdoor heat exchanger (13) in which the refrigerant is condensed during the cooling operation and the outdoor fan (Fo) is arranged in proximity, a decompression unit (14) for decompressing the refrigerant during the defrost operation, and an accumulator (15). ). The pressure reducing unit (14) has two branches, one of which is provided with a capillary tube (CP) and the other of which is provided with a check valve (CV). This check valve (CV)
Only the flow of the refrigerant flowing from the external heat exchanger (13) toward the internal unit (1B) is allowed.

Further, an oil separator (16) for filtering the lubricating oil in the discharged gas is provided on the discharge side of the compressor (11).
The lubricating oil separated by the oil separator (16) is supplied to an accumulator (1) by an oil recovery pipe (17) equipped with a capillary tube (CP).
It is designed to be collected downstream of 5). The oil separator (16) is not always necessary, and is particularly necessary when a compressor in which lubricating oil is apt to be mixed into the discharge gas is used. A liquid line (18) and a suction gas line (19) are connected to the external unit (1A), and an injection circuit that supplies a part of the liquid refrigerant to the suction side of the compressor (11).
(20) is provided. This injection circuit (20)
Has two branches on the side connected to the intake gas line (19), and the branch pipes (20a, 20b) have solenoid valves (SV-1, SV-
2) and capillary tubes (CP, CP) are provided. The solenoid valve (SV-1) provided in one branch pipe (20a) is always opened during operation. The solenoid valve (SV-2) provided in the other branch pipe (20b) is opened when the discharge pipe temperature of the compressor (11) reaches a predetermined value (for example, 100 ° C) or more, and the discharged gas refrigerant is overheated. The degree is adjusted. still,
The injection circuit (20) does not necessarily have to be branched into two, and is constituted by only one pipe,
A valve that performs the same operation as the above-described solenoid valve (SV-2) may be provided.

On the other hand, the in-compartment unit (1B) has an expansion valve (21) for reducing the pressure of the refrigerant and an in-compartment heat exchanger (22) in which the refrigerant evaporates during the cooling operation and an outdoor fan (Fi) is arranged in close proximity. ) Is arranged.

The expansion valve (21) is constituted by an external pressure equalizing type temperature-sensitive expansion valve, and the temperature-sensitive cylinder (23) is connected to the internal heat exchanger (22).
And an external pressure equalizing pipe (25) is connected to the gas side pipe (24). The external pressure equalizing pipe (25)
The expansion valve is connected to a mounting portion of the temperature sensing tube (23) in the gas side pipe (24) so that the gas refrigerant has a predetermined degree of superheat.
(21) is designed to open at a predetermined opening.

Further, the internal heat exchanger (22) and the expansion valve (2
A drain pan heater (26) is branched from between (1) and (1). The drain pan heater (26) is provided with a check valve (CV). The drain pan heater (26) is for removing frost that has fallen from the internal heat exchanger (22) or the like to a drain pan (not shown) during the defrost operation.

The external unit (1A) and the internal unit (1B) are connected by connecting pipes (31, 32) on the liquid side and the gas side, whereby a refrigerant circuit is formed by connecting the above-mentioned devices by piping. (30) is constituted.

The gas-side connecting pipe (32) of the connecting pipes (31, 32) connecting the external unit (1A) and the internal unit (1B) is provided with a proportional control valve (35). . This proportional control valve (35)
The opening degree can be freely adjusted, and the refrigeration capacity is adjusted by adjusting the opening degree. That is, when the opening of the proportional control valve (35) is reduced while the compressor (11) is constantly driven during the cooling operation, the pressure loss on the suction side of the compressor (11) increases. The evaporating temperature rises by this pressure loss, which reduces the evaporator capacity. Conversely, if the opening of the proportional control valve (35) is increased,
(11) The pressure loss on the suction side is reduced and the evaporation temperature is reduced, thereby increasing the evaporator capacity.

The feature of this embodiment is that the compressor (11)
Is provided with a hot gas bypass pipe (36) as hot gas supply means for guiding a part of the discharged refrigerant to the upstream side (inside the internal heat exchanger) of the proportional control valve (35). The hot gas bypass pipe (36) has one end connected to the discharge side of the compressor (11) and the other end connected to the proportional control valve (35) and the internal heat exchanger (22) in the gas side communication pipe (32). Connected between them. The hot gas bypass pipe (36) has a capillary tube (C
P) and solenoid valve (SV-3) are provided.
At the time of opening 3), a part of the refrigerant discharged from the compressor (11) is guided to the upstream side of the proportional control valve (35).

The apparatus is provided with a plurality of sensors. On the discharge side of the compressor (1), there is provided a high pressure switch (HPS1) that outputs an abnormal signal when the high pressure refrigerant pressure rises abnormally. A high-pressure pressure sensor (HPS2) for detecting the pressure of the high-pressure refrigerant is provided in a pipe through which the discharged refrigerant flows during the defrost operation. On the suction side of the compressor (11), a low-pressure switch (LPS1) that outputs an abnormal signal when the low-pressure refrigerant pressure abnormally drops, and a low-pressure pressure sensor (LPS2) that detects the low-pressure refrigerant pressure in order to control the low-pressure refrigerant pressure. )
Is provided. The internal air intake of the internal unit (1B) has an internal temperature sensor (Th-
i) is provided.

Each device of each unit (1A, 1B) is controlled by a controller (50). In other words, control of each solenoid valve (SV-1 to SV-3) and proportional control valve (35),
The air flow of each fan (Fo, Fi) is controlled by the controller (50).

Next, the operation of the above-structured apparatus will be described.

During the cooling operation, the four-way switching valve (12) is switched to the solid line side in the figure, and the compressor (11) is driven and each fan (Fo, Fi) is driven.

In this state, the refrigerant discharged from the compressor (11) passes through the four-way switching valve (12) and passes through the external heat exchanger (13).
Condenses into a liquid refrigerant and flows to the indoor unit (1B) via the liquid line (18). After the pressure of the liquid refrigerant is reduced by the expansion valve (21), the liquid refrigerant evaporates in the internal heat exchanger (22) to become a gas refrigerant, and flows through the proportional control valve (35). This proportional control valve (35)
The opening degree is adjusted according to the inside temperature detected by the inside temperature sensor (Th-i). Specifically, when the internal temperature is lower than the set temperature, the opening of the proportional control valve (35) is reduced. As a result, the pressure loss on the suction side of the compressor (11) increases, and the evaporating temperature increases by the amount of the pressure loss, and the evaporator capacity decreases. Therefore, the internal temperature is raised to approach the set temperature. Conversely, when the internal temperature is higher than the set temperature, the opening of the proportional control valve (35) is increased. As a result, the pressure loss on the suction side of the compressor (11) is reduced, the evaporation temperature is reduced, and the evaporator capacity is increased. Therefore, it becomes possible to lower the internal temperature to the set temperature. By repeating such an operation, the internal temperature is maintained at the set temperature.

The operation of this embodiment is characterized in that a part of the refrigerant discharged from the compressor (11) is supplied to the upstream side of the proportional control valve (35) by the hot gas bypass pipe (36) during the cooling operation. is there. That is, the solenoid valve of this hot gas bypass pipe (36)
By opening (SV-3), high-pressure gas refrigerant is supplied to the upstream side of the proportional control valve (35). According to such an operation, the refrigerant evaporated in the internal heat exchanger (22) and the high-pressure gas refrigerant flow through the proportional control valve (35) in a mixed state. That is, since the flow rate of the refrigerant flowing through the proportional control valve (35) can be increased, the action on the internal heat exchanger (22) when opening and closing the proportional control valve (35) can be significantly exerted.
This is because, when the proportional control valve (35) is throttled, the degree of pressure reduction on the upstream side is proportional to the square of the flow rate change amount in the proportional control valve (35). Therefore, by increasing the flow rate of the refrigerant flowing through the proportional control valve (35) in advance, even if the proportional control valve (35) is slightly squeezed, the change in the flow rate becomes large, and the change amount of the pressure loss is correspondingly increased. And the evaporation temperature of the internal heat exchanger (22) can be greatly reduced. In other words, the rate of change of the evaporation temperature of the internal heat exchanger (22) with respect to the amount of change in the opening of the proportional control valve (35) can be increased. Thereby, the control range of the evaporation temperature of the internal heat exchanger (22) by the proportional control valve (35) can be expanded.

Further, since the suction pressure of the compressor (11) can be increased, it is possible to avoid the occurrence of a situation in which the discharge pipe temperature rises excessively as the compression ratio increases as in the prior art. You can also.

Further, the present apparatus (10) performs a defrosting operation (defrost operation) every predetermined time such as 4 hours. During this operation, the four-way switching valve (12) is switched to the broken line side in the figure, and the proportional control valve (35) is fully opened. In addition, each fan (F-
o, Fi) is stopped. As a result, the hot gas (high-temperature gas refrigerant) discharged from the compressor (11) is supplied to the four-way switching valve.
(12) and reaches the internal heat exchanger (22), where the internal heat exchanger (2
2) Remove the frost. Thereafter, the refrigerant reaches the pressure reducing section (14) via the drain pan heater (26). Here, the pressure is reduced in the capillary tube (CP), the heat is exchanged with the outside air in the external heat exchanger (13), and the vapor is returned to the compressor (11).

As described above, according to this embodiment, the high pressure gas refrigerant is supplied to the upstream side of the proportional control valve (35) during the cooling operation, so that the amount of change in the opening degree of the proportional control valve (35) can be reduced. The rate of change of the evaporation temperature of the internal heat exchanger (22) can be increased, and the control range of the evaporation temperature of the internal heat exchanger (22) by the proportional control valve (35) can be expanded. In addition, an excessive rise in the discharge pipe temperature can be avoided. in this way,
The ability to extend the control range of the evaporating temperature means that a larger proportional control valve can be used for the horsepower of the refrigeration system (10), and the refrigeration system (10) maximizes its capacity. Even when it is exerted, a large control range can be ensured while the pressure loss at the proportional control valve is relatively small.

In this embodiment, the proportional control valve (35) is provided on the gas side communication pipe (32). However, the present invention is not limited to this, and the suction gas line (19) in the external unit (1A) is not limited to this. ) Can be provided at an appropriate location on the gas side of the internal heat exchanger (22).

[0035]

As described above, according to the present invention, the following effects can be obtained. According to the first aspect of the present invention, the pressure loss means (35) for varying the evaporation temperature of the evaporator (22) by adjusting the pressure loss on the suction side of the compressor (11) is provided on the suction side of the compressor (11). A part of the refrigerant discharged from the compressor (11) is supplied to the upstream side of the pressure loss means (35) by the hot gas supply means (36) to the provided refrigerating apparatus. Thereby, in the pressure loss means (35), the pressure loss can be increased even if the ratio of the flow rate change amount when the pressure loss to the total flow rate in the state where the pressure loss is not generated is small. Therefore, the control range of the evaporation temperature of the evaporator (22) by the pressure loss means (35) can be expanded, and the practicality of the device can be improved. Further, by increasing the suction pressure of the compressor (11), it is possible to suppress an excessive rise in the temperature of the discharge pipe due to an increase in the compression ratio, thereby improving reliability.

According to the second aspect of the present invention, the pressure loss means is a proportional control valve (35) whose opening can be adjusted, and the evaporating temperature of the evaporator (22) is controlled by changing the opening of the proportional control valve (35). The range can be expanded, and the adjustment of the evaporation temperature can be easily performed.

According to the third aspect of the present invention, the expansion mechanism is an external pressure equalizing type temperature-sensitive expansion valve (21). In this expansion valve, when the refrigerant circulation amount decreases as a whole circuit, the opening degree increases with an increase in the superheat degree of the refrigerant at the evaporator outlet side, and the pressure loss at the pressure loss means (35) tends to increase. However, according to the present invention, as described above, the increase in the pressure loss can be suppressed and the control range of the evaporation temperature can be expanded.

According to the present invention, a part of the liquid refrigerant condensed by the condenser (13) is supplied to the suction side of the compressor (11) by the injection circuit (20), and the supply amount is adjusted. Adjustable with valves (SV-1, SV-2). Thereby, it is possible to suppress the superheat degree of the discharge gas of the compressor (11) from being excessively increased, and it is possible to appropriately adjust the superheat degree and perform a stable operation.

[Brief description of the drawings]

FIG. 1 is a refrigerant piping system diagram of a refrigeration apparatus according to an embodiment.

[Explanation of symbols]

(11) Compressor (13) External heat exchanger (condenser) (20) Injection circuit (21) Expansion valve (expansion mechanism) (22) Internal heat exchanger (evaporator) (30) Refrigerant circuit (35 ) Proportional control valve (pressure loss means) (36) Hot gas bypass pipe (hot gas supply means)

Claims (4)

[Claims] 1. A compressor (11), a condenser (13), and an expansion mechanism
(21), and a refrigerant circuit (30) in which an evaporator (22) is connected in order so that refrigerant can be circulated, causing a pressure loss on the suction side of the compressor (11) on the suction side, and Evaporator (22) by adjusting its loss pressure
In a refrigerating apparatus provided with a pressure loss means (35) for varying the evaporation temperature of the compressor, a hot gas supply means (36) for supplying a part of the refrigerant discharged from the compressor (11) to the upstream side of the pressure loss means (35). ) Is provided. 2. The refrigeration system according to claim 1, wherein the pressure loss means is a proportional control valve (35) whose opening is adjustable. 3. The refrigeration system according to claim 1, wherein the expansion mechanism is an external pressure equalizing type temperature-sensitive expansion valve (21). 4. The injection system according to claim 1, wherein a part of the liquid refrigerant condensed in the condenser (13) is supplied to a suction side of the compressor (11) and to a downstream side of the pressure loss means (35). Circuit (20), and the injection circuit (20) is provided with regulating valves (SV-1, SV-2) capable of adjusting the supply amount of the liquid refrigerant to the suction side of the compressor (11). A refrigeration apparatus characterized by the above-mentioned.