JPH0339866A - Refrigerator - Google Patents

Abstract

PURPOSE:To prevent abrupt variation in total output of both a rotating speed variable compressor and a constant capacity compressor by setting the maximum capacity of the variable compressor to a value smaller than the rated capacity of the constant compressor, providing a bypass passage over a refrigerant discharge tube and a refriger ant suction tube, and providing a bypass valve in the bypass passage. CONSTITUTION:For example, a rotating speed variable compressor 3 is varied at its operating frequency by an inverter 2 from 1.2 horsepower of minimum capacity to 4 horsepower of maximum capacity, and a constant capacity compressor 4 has 6 horsepower of rated capacity. When the capacity control range of the compressor 3 is 30% (1.2 horsepower) - 100% (4 horsepower), the total output control range of both the compressors 3 and 4 become 1.2 - 10 horsepower. Since the lower limit value of the output control range is lowered, the frequency of stopping and starting the compressor 3 is reduced to decrease variation in a room temperature. Bypass passages 20, 21 are provided over between a refrigerant discharge tube 9 and a refrigerant suction tube 10, and bypass valves 22, 23 are respectively provided in the bypass passages. If the compressor 4 is started or stopped, the valves 22, 23 are opened or closed. Accordingly, total output from the compressor is not abruptly varied.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to a refrigeration system suitable for a heat pump type air conditioner that cools and heats multiple rooms.

(b) Conventional technology A refrigeration system in which a variable rotation speed compressor and a constant capacity compressor are connected in parallel, and a refrigerant circuit is formed by sequentially connecting these compressors, condensers, pressure reducers, and evaporators. The device is actually fair 1-
It is presented in Publication No. 9280.

(c) Problems to be Solved by the Invention In the device presented in the above publication, the variable speed compressor and the constant capacity compressor have the same capacity, for example, the total capacity of both compressors is 10 horsepower and the rotation speed is Assuming that the capacity control range of the variable compressor is 30% (1.5 horsepower) to 100% (5 horsepower),
The total capacity control range of both compressors is 1.5 horsepower to 10 horsepower, and when the capacity corresponding to the air conditioning load becomes less than 1.5 horsepower, the variable speed compressor starts and stops more frequently, and the room temperature The problem was that there were many fluctuations.

It is an object of the present invention to provide a refrigeration system that solves these problems and prevents the total output from both compressors from fluctuating rapidly.

(d) Means for Solving the Problems The present invention provides a refrigeration system in which a variable rotation speed compressor and a constant capacity compressor are connected in parallel, in which the maximum capacity of the variable rotation speed compressor is reduced to constant capacity compression. This is set to be smaller than the rated capacity of the machine.

Further, the present invention provides a refrigeration system in which a variable rotation speed compressor and a variable pole compressor are connected in parallel, in which the maximum capacity of the variable rotation speed compressor is greater than the maximum capacity of the variable pole compressor. This is set to a small value.

In addition, the present invention provides a refrigeration system in which a variable rotation speed compressor and a capacity-saving type compressor that returns part of the refrigerant during compression to the suction side are connected in parallel, in which the maximum capacity of the variable rotation speed compressor is increased. The capacity is set smaller than the maximum capacity of the capacity saving type compressor.

Further, the present invention provides a refrigeration system in which a variable speed compressor and a constant capacity compressor are connected in parallel, in which the maximum capacity of the variable speed compressor is set smaller than the rated capacity of the constant capacity compressor. On the other hand, a bypass path is provided across the refrigerant discharge pipe and refrigerant suction pipe of both compressors, and in this bypass path, the operating capacity of the variable speed compressor is minimized and the constant capacity compressor is The system is equipped with a bypass valve that opens and closes when the engine starts and stops.

Further, the present invention provides a refrigeration system in which a variable rotation speed compressor and a variable pole compressor are connected in parallel, in which the maximum capacity of the variable rotation speed compressor is greater than the maximum capacity of the variable pole compressor. At the same time, a bypass path is provided across the refrigerant discharge pipe and refrigerant suction pipe of both compressors, and the operating capacity of the variable speed compressor is minimized and the number of poles is changed. A bypass valve is provided that opens and closes when the type compressor starts and stops and changes the number of poles.

In addition, the present invention provides a refrigeration system in which a variable rotation speed compressor and a capacity-saving type compressor that returns part of the refrigerant during compression to the suction side are connected in parallel, in which the maximum capacity of the variable rotation speed compressor is increased. While setting the capacity to be smaller than the maximum capacity of the capacity saving type compressor, a bypass passage is provided across the refrigerant discharge pipe and the refrigerant suction pipe of both compressors, and this bypass passage is used for the variable speed compressor. A bypass valve is provided that opens and closes when the capacity saving type compressor starts and stops when the operating capacity reaches its minimum.

<*) For example, the maximum capacity of a variable operating speed compressor is 4 horsepower, the rated capacity of a constant capacity compressor is 6 horsepower, or the maximum capacity of a pole change type compressor or a capacity saving type compressor is 6 horsepower. The capacity control range of the variable speed compressor is set to 30% (1, 2
horsepower) to 100% (4 horsepower), the total output control range of the same compressor is 1.2 horsepower to 10 horsepower, and as the lower limit of the output control range decreases, the frequency at which the variable speed compressor starts and stops. This reduces room temperature fluctuations.

At the same time, the operating capacity of the variable speed compressor becomes the minimum, and the constant capacity compressor, pole number change type compressor, and capacity save type compressor start and stop, or the pole number of the pole number change type compressor changes. Time,
Since the bypass valve is opened and closed, the total output from the compressor does not fluctuate rapidly.

(F) Embodiment The first embodiment of the present invention will be explained based on FIGS. 1 and 2. (1) The operating frequency is changed by the inverter device (2), and the minimum capacity is 1.2 horsepower and the maximum capacity is 1.2 horsepower. A variable speed compressor (3) with a capacity of 4 horsepower, a constant capacity compressor (4) with a rated capacity of 6 horsepower, and a heat source side heat exchanger (5)
and a gas-liquid separator (6), a heat source side unit (7)
a) (7b) <7c) lt user side heat exchanger (8a) (
8b) (8c) and has a capacity of 1.5 horsepower, 3.5 horsepower, and 5 horsepower, and a heat source side heat exchanger (5 horsepower).
) is both compressed 1! (3) The refrigerant discharge pipe (9) and the refrigerant suction pipe (10> of ) (7b) and (7c) are connected to the high-pressure gas pipe <13> which is branch-connected to the refrigerant discharge pipe (9>), and the low-pressure gas pipe which is branch-connected to the refrigerant suction pipe (10>). It consists of a pipe (14) and a liquid pipe (15) connected to the heat source side heat exchanger <5), and each user side heat exchanger <8a> (8b) (8c) is connected to a high pressure gas pipe (] 3> and the low pressure gas pipe (14) are provided with switching valves (16a) (17a), respectively.
), (16b)(17b), (16c)(17
C), and the liquid pipe (15) is connected to a refrigerant pressure reducer (18a) (18b) (18c) such as an electric expansion valve.
).

(19) is the discharge branch pipe (9a) of the constant capacity compressor (4)
The check valves (20) and (21) are installed in the refrigerant discharge pipe (
9> and the refrigerant suction pipe (10>), and this bypass path is equipped with a variable rotation speed compressor (3).
) are provided with bypass valves (22) and (23) that open and close when the constant capacity compressor (4) starts and stops when the operating capacity of the It is designed to be opened and closed.

Next, the driving operation will be explained. When cooling all rooms at the same time, open one switching valve (11a) of the heat source side heat exchanger (5) and close the other switching valve (llb), and close the user side heat exchanger (7a) (7b). (7c) One switching valve (16
a) By closing (16b) (16c) and opening the other switching valve (17a) (17b) (17c), the refrigerant discharged from the compressor (3) (4) is transferred to the discharge pipe (9),
- The refrigerant flows sequentially through the switching valve (lla) and the heat source side heat exchanger (5), where it is condensed and liquefied, and then passes through the liquid pipe (15) to the refrigerant pressure reducer of each user side unit (7a) (7b) (7C). (18
a)<18b) (18c) where it is depressurized. After that, each user side heat exchanger (8a) (sb) (8
After evaporation in step c), the switching valves (17a) and (17b) are used.
) (17c), low pressure gas pipe (14>, suction pipe (10>,
It passes through the gas-liquid separator (6>) in sequence and is sucked into the compressor (3) and (4).

In this way, each user-side heat exchanger (which acts as an evaporator)
8a) (8b) (8c) All rooms are cooled at the same time.

Conversely, if you want to heat all rooms at the same time, use the heat source side heat exchanger (5
) closes one switching valve (lla) and opens the other switching valve (llb), and also closes one switching valve (lla) of the heat exchanger (8a) (8) on the user side.
b) One switching valve (16a) (16b) (1
6c) and open the other switching valve (17a) (17b).
By closing (17c), the refrigerant discharged from the compressors (3) (4>) is transferred to the discharge pipe (9>) and the high pressure gas pipe (13).
The refrigerant is sequentially distributed to the switching valves (16a) (16b) (16c) and the user-side heat exchangers (8a) (8b) (8c), where it is condensed and liquefied, and then transferred to each refrigerant pressure reducer (18a).
The pressure is reduced in (18b) and (18c) and the liquid is merged in the liquid pipe (15). After that, it is evaporated and vaporized in the heat source side heat exchanger (5). Liquid separator (6
) and is then sucked into the compressor (3) and (4). Each user-side heat exchanger (8g) acts as a condenser in this way (
8b) (8e) all rooms are heated at the same time.

The operating operations of the variable speed compressor (3) and constant capacity compressor (4) and the opening/closing operations of the bypass valves (22) and (23) in such simultaneous cooling operation and simultaneous warming S operation are shown in FIG. To explain, first, the variable speed compressor (3) has a minimum capacity of 1.2 using the output signal from the inverter device (2).
When the operation starts with horsepower (point A) and reaches a capacity of 3.6 horsepower (point B), the minimum capacity drops to 1.2 horsepower, and at the same time, the constant capacity compressor <4> is activated by a signal from the controller (24). A bypass valve (22) with a rated capacity of 6 horsepower and a bypass capacity of 30% and a bypass valve (22) with a bypass capacity of 20%
3> is opened and the operating capacity of the constant capacity compressor (4) after starting operation, that is, the operating capacity of the constant capacity compressor (4) is 6 horsepower and the operating capacity of the variable speed compressor (3) is 1. Total capacity cuff with 2 horsepower.

The operating capacity before starting operation of the constant capacity compressor (4) from 2 horsepower, that is, the operating capacity of the variable speed compressor (3) 3.6 horsepower (total capacity cuff, 2 50% of the horsepower) is bypassed from the discharge pipe (9) to the suction pipe (10) through the bypass valves (22) and (23) having a total bypass volume of 50%. When the constant capacity compressor (4) starts operating at the same time as the variable speed compressor (3) decreases from 3.6 horsepower to 1.2 horsepower, the discharge pipe from both compressors (3) <4) The total output sent to the high-pressure gas pipe (13) via (9) increases linearly, and there is no risk of sudden changes in the room temperature.Then, the operating capacity of the variable speed compressor (3) increases. When it reaches 4 horsepower (0 point), the bypass valve with 20% bypass capacity (2
3> closes, and then the operating capacity of the variable speed compressor (3) reaches 2°2 horsepower and decreases to 1.2 horsepower (point D), and a signal from the controller (24>) causes the bypass capacity to be increased. At the same time as the 20% bypass valve (23) opens, the bypass volume! The 30% bypass valve (22) closes, and then the variable speed compressor (3
)'s operating capacity reaches 3 horsepower and decreases to 1.2 horsepower (
Point E) and the bypass valve (23) with a bypass capacity of 20% are closed, and after that, the operating capacity of the variable speed compressor (3) reaches 4 horsepower, and the operating capacity of the constant capacity compressor (4>) reaches 6 horsepower. The high-pressure gas pipe (13
) will increase linearly and the room temperature will not fluctuate rapidly.

In this way, during simultaneous cooling operation and simultaneous heating operation,
The user units (7a), (7b, and 7c) are operated for cooling and heating with a maximum operating capacity of 10 horsepower; When the user unit!-(7e) goes off, the variable speed compressor (3) and bypass valve (22
) (23> is a reverse operation to the above-mentioned operation (shifting from point E to point C), and the total output decreases linearly, and the total output decreases to 3.6 horsepower, resulting in variable speed compression. When the machine (3) decreases to the minimum capacity of 1.2 horsepower (point B), the controller (24
) When the constant capacity compressor (4) stops operating, the bypass valves (22) and (23) close at the same time, increasing the operating capacity of the variable speed compressor (3) to 3.6 horsepower. Therefore, the output delivered to the high pressure gas pipe (13) via the discharge pipe (9) is also 3.6 horsepower.In this way, the output decreases linearly, so there is no sudden change in the room temperature.

Then, the user unit 1-(7
b) becomes less than 1.5 horsepower due to a decrease in the indoor heating and cooling load, and accordingly, the operating capacity of the variable speed compressor (3) decreases to 1.5 horsepower and further to the lower limit of 1.2 horsepower. Since the variable speed compressor (3) is operated continuously until the rotation speed is reached, the frequency of starting and stopping of the variable speed compressor (3) is reduced, and room temperature fluctuations can be kept to a minimum.

In addition, when simultaneously cooling two units and heating one room at the same time, switch the switching valve (lla) of one of the heat source side heat exchangers (5).
One (7) switching valve (16a) (16b) of the cooling user unit (7a) (7e) is opened, the other switching valve (llb) is closed, and the other switching valve (17a) ( 17e) and open one switching valve (16b) of the heating user unit (7b) and close the other switching valve (i7b), compression a(3)(4)
A part of the refrigerant discharged from the discharge pipe (9) and the switching valve (l
la) is sequentially repeated to flow to the heat source side heat exchanger (5), and the remaining refrigerant passes through the high pressure gas pipe (13) for heating. 8b>, and is condensed and liquefied in this utilization side heat exchanger (7b) and heat source side heat exchanger (5).Then, the refrigerant condensed and liquefied in these heat exchangers (8b) and (5) is Liquid pipe
15), the refrigerant pressure is reduced in the refrigerant pressure reducers (18a) (i8C) of the usage side units (7a) (7c), and then evaporated in the respective usage side heat exchangers (8a) (8C>). ,
The low pressure gas pipe (14) passes through each switching valve (17a) (17c).
> and is suctioned into the compressor (3) and (4) through the suction pipe (10) and the gas-liquid separator (6) sequentially.In this way, the user-side heat exchanger (8b) acts as a condenser. - The room is heated and another user heat exchanger (8
a) Two units are cooled in (8c).

During such simultaneous cooling and heating operation, the operating capacity of the heating user unit (7b) is 3.5 horsepower and the total operating capacity of the cooling user units (7a) (7c) is 6.5 horsepower. and corresponds to the larger 6.5 horsepower (G point)
The variable speed compressor (3) has 2.1 horsepower and constant capacity compression 13! (4) is operated at 6 horsepower, the bypass valve (22) with a bypass capacity of 30% is closed, and the bypass valve (23) with a bypass capacity of 20% is opened, so that the total of the internal compressors (3) and (4) is 80% capacity (approximately 6.5 horsepower) of the capacity 8.1 horsepower is output.

Figures 3 and 4 show a second embodiment of the present invention, in which the operating frequency is changed by an inverter device (2), and the rotation speed is variable with a minimum capacity of 1.2 horsepower and a maximum capacity of 4 horsepower. The number of poles is switched between 2 and 4 poles by the type compressor (3) and the pole number converter (25), resulting in a minimum capacity of 3 horsepower (4-pole operation) and a maximum capacity of 6 horsepower (2-pole operation). A pole change type compressor (26) is connected in parallel, and a refrigerant discharge pipe (
9) and the refrigerant suction pipe (10).
7> is a variable speed compressor (3> has the minimum operating capacity (
1.2 horsepower) and connects a bypass valve (28) with a bypass capacity of 5% that opens and closes with a signal from the controller (24) when the pole number change type compressor (26) starts, stops, or changes the number of poles. The operation operations of simultaneous cooling operation, simultaneous heating operation, and simultaneous cooling and heating operation are the same as in the first embodiment, so the same reference numerals are given and explanations are omitted.Due to the above differences. The control operation will be explained based on FIG. 4. When the output increases, the pole change type compressor (26) starts operating at 4 poles (3 horsepower), or when the output decreases, the pole change type compressor (26) starts operating at 4 poles (3 horsepower).
When 6〉 stops operating at 4 poles (3 horsepower) (point H), and when the output increases, the pole change type compressor (26〉 switches from 4 poles (3 horsepower) to 2 poles (6 horsepower). , or when the output decreases, the pole number change type compressor (26) changes from 2 poles (6 horsepower) to 4 poles (
3 horsepower) (1 point), the bypass valve (28)
By opening and closing, the output increases or decreases linearly, and the room temperature does not fluctuate rapidly.

Figures 5 and 6 show a third embodiment of the present invention, in which the operating frequency is changed by an inverter device (2), and the rotation speed is variable with a minimum capacity of 1.2 horsepower and a maximum capacity of 4 horsepower. 3 by mold compressor (3) and capacity save device (29)
The 0% capacity save valve (30) opens and closes and the minimum capacity is 4.
Capacity-saving type compressor with 2 horsepower and maximum capacity of 6 horsepower (
31> are connected in parallel, and a bypass passage (27> that spans the refrigerant discharge pipe (9>) and the refrigerant suction pipe (10) is connected in parallel to Bypass capacity 25% that opens and closes with the signal from the controller 24) when the capacity saving type compressor (31) starts and stops at 1.2 horsepower).
The difference from the first embodiment is that a bypass valve <32> is connected, and the operation operations of simultaneous cooling operation, simultaneous heating operation, and simultaneous cooling and heating operation are the same as in the first embodiment, and are given the same reference numerals. The explanation will be omitted. The control operation based on the above differences will be explained based on Fig. 6. When the output increases, the capacity save type compressor (31) starts operating at 4.2 horsepower, or when the output decreases, the capacity save type compressor (31) starts operating at 4.2 horsepower. When the engine stops operating at 4.2 horsepower (1 point), the bypass valve (32) is opened and closed, and the output increases or decreases linearly.
Room temperature does not fluctuate rapidly.

Figures 7 and 8 show a fourth embodiment of the present invention, in which the operating frequency is changed by an inverter device (2), and the rotation speed is variable with a minimum capacity of 1.2 horsepower and a maximum capacity of 4 horsepower. The number of poles is switched between 2 and 4 poles by the type compressor (3) and the pole number converter (25), resulting in a minimum capacity of 3 horsepower (4-pole operation) and a maximum capacity of 6 horsepower (2-pole operation). A pole change type compressor (26) with a rated capacity of 10 horsepower and a constant capacity compressor (33) with a rated capacity of 10 horsepower are connected in parallel, and a refrigerant discharge pipe (
9> Bypass path spanning the no-refrigerant suction pipe (10) (
27) When the operating capacity of the variable speed compressor (3) reaches the minimum (1 or 2 horsepower) and the pole change type compressor (26) starts and stops and changes the number of poles, or when the constant capacity type The difference from the first embodiment is that a bypass valve (34) with a bypass capacity of 12% is connected, which opens and closes in response to a signal from the controller (24) when the compressor (33) starts and stops. The operation operations of the simultaneous heating operation and the simultaneous cooling and heating operation are the same as those of the first embodiment, so the same reference numerals are given and the explanation will be omitted.

To explain the control operation based on the above differences based on FIG. 8, when the output increases, the pole change type compressor (26)
When the compressor (26) starts operating at 4 poles (3 horsepower) or stops operating at 4 poles (3 horsepower) when the output decreases (K
point), and when the output increases, the pole-changing compressor (26) often switches from 3-pole (3 horsepower) to 2-pole (6 horsepower), or when the output decreases, the pole-changing compressor (26) switches from 2-pole to 2-pole (6 horsepower). (6 horsepower) to 4-pole (3 horsepower) (L point), and when the constant capacity compressor (33) starts operating when the output increases or stops operating when the output decreases (M point) to Bi-fit B(
30 is opened and closed, the output increases or decreases linearly, and the room temperature does not fluctuate rapidly.

In each of the above embodiments, the unit-to-unit piping (12) is replaced by a high pressure gas pipe (13), a low pressure gas pipe (14), and a liquid pipe (15).
Since it is composed of three refrigerant pipes, it has a simple circuit configuration using a single-function heat source side heat exchanger, and can perform simultaneous cooling and heating operations of multiple user-side units as well as heating and cooling operations. Simultaneous operation can be freely selected on any user-side unit, and during simultaneous heating and cooling operation, the user-side heat exchanger that acts as a condenser and the user-side heat exchanger that acts as an evaporator are connected in series. Therefore, it is possible to perform efficient operation by heat recovery, but the present invention is not limited to such a refrigerant circuit.

(G) Effects of the Invention According to the present invention, the maximum capacity of a variable speed compressor is the rated capacity of a constant capacity compressor, the maximum capacity of a pole change type compressor,
Since the capacity is set lower than the maximum capacity of the capacity saving type compressor, the lower limit of the total output is lowered and the output control range is expanded, which reduces the frequency of the variable speed compressor starting and stopping, resulting in comfortable air conditioning with less room temperature fluctuation. It is possible to improve the operating efficiency, and since the compressors have different capacities, it is possible to improve the oil balance between the compressors.

At the same time, the operating capacity of the variable speed compressor becomes the minimum, and the constant capacity compressor, pole number change type compressor, and capacity save type compressor start and stop, or the pole number of the pole number change type compressor changes. Time,
Since the bypass valve is opened and closed, proportional control from small to large output can be performed using a small capacity inverter device, and sudden fluctuations in output can be prevented.

[Brief explanation of drawings]

Fig. 1 is a refrigerant circuit diagram of a refrigeration system showing a first embodiment of the present invention, Fig. 2 is an explanatory diagram showing control operations of a compressor and a bypass valve in the same embodiment, and Fig. 3 is a diagram showing a second embodiment of the present invention. A refrigerant circuit diagram of a refrigeration system showing an embodiment, FIG. 4 is an explanatory diagram showing control operations of a compressor and a bypass valve in the same embodiment, and FIG. 5 is a refrigerant circuit of a refrigeration system showing a third embodiment of the present invention. Fig. 6 is an explanatory diagram showing the control operation of the compressor and bypass valve in the same embodiment, Fig. 7 is a refrigerant circuit diagram of a refrigeration system showing the fourth embodiment of the present invention, and Fig. 8 is the same embodiment. It is an explanatory view showing control operation of a compressor and a bypass valve in . (3)...Variable rotation speed compressor, (4)(33)・
... Constant capacity compressor, <9> ... Refrigerant discharge pipe, ri10) ... Refrigerant suction pipe, (20) (21) (27)
...Bypass road, (22) (23) (28) (32
)(34)...Bypass valve, (26)...Pole change type compressor, (31)...Capacity saving type compressor.

Claims (6)

[Claims] (1) In a refrigeration system in which a variable rotation speed compressor and a constant capacity compressor are connected in parallel, and a refrigerant circuit is formed by sequentially connecting both compressors, a condenser, a pressure reducer, and an evaporator, A refrigeration system characterized in that the maximum capacity of a variable rotation speed compressor is set smaller than the rated capacity of a constant capacity compressor. (2) In a refrigeration system in which a variable rotation speed compressor and a pole change type compressor are connected in parallel, and a refrigerant circuit is formed by sequentially connecting both compressors, a condenser, a pressure reducer, and an evaporator. A refrigeration system characterized in that the maximum capacity of the variable rotation speed compressor is set smaller than the maximum capacity of the pole change type compressor. (3) A variable speed compressor and a capacity-saving compressor that returns part of the refrigerant during compression to the suction side are connected in parallel, and these compressors, condenser, pressure reducer, and evaporator are connected in sequence. A refrigeration system which is connected to form a refrigerant circuit, characterized in that the maximum capacity of a variable rotation speed compressor is set smaller than the maximum capacity of a capacity saving type compressor. (4) In a refrigeration system in which a variable speed compressor and a constant capacity compressor are connected in parallel, and a refrigerant circuit is formed by sequentially connecting both compressors, a condenser, a pressure reducer, and an evaporator, While the maximum capacity of the variable speed compressor is set to be smaller than the rated capacity of the constant capacity compressor, a bypass path is provided across the refrigerant discharge pipe and refrigerant suction pipe of both compressors, and this bypass 1. A refrigeration system characterized in that a bypass valve is provided in the passageway, which opens and closes when the operating capacity of the variable speed compressor reaches a minimum and the constant capacity compressor starts and stops. (5) In a refrigeration system in which a variable rotation speed compressor and a pole change type compressor are connected in parallel, and a refrigerant circuit is formed by sequentially connecting both compressors, a condenser, a pressure reducer, and an evaporator. The maximum capacity of the variable speed compressor is set smaller than the maximum capacity of the pole change type compressor, while a bypass path is provided across the refrigerant discharge pipe and refrigerant suction pipe of both compressors. A refrigeration system characterized in that the bypass path is provided with a bypass valve that opens and closes when the operating capacity of the variable rotation speed compressor reaches a minimum and the pole number changeable compressor starts and stops and changes the number of poles. (6) A variable speed compressor and a capacity-saving compressor that returns part of the refrigerant during compression to the suction side are connected in parallel, and these compressors, condensers, pressure reducers, and evaporators are connected in sequence. In a refrigeration system in which a refrigerant circuit is formed by A bypass path is provided across the compressor, and this bypass path is provided with a bypass valve that opens and closes when the operating capacity of the variable speed compressor reaches a minimum and the capacity saving compressor starts and stops. Refrigeration equipment.