JPH0299786A - Refrigerating device - Google Patents

Abstract

PURPOSE:To prevent the burn of the bearing metal of a compressor having the less operation faculty by connecting a plurality of compressors and an oil separator installed in a high pressure discharge conduit through an oil return pipe and installing a selecting means in the oil return pipe. CONSTITUTION:A plurality of compressors 2a and 2b are connected in parallel, and an oil separator 17 is installed in the high pressure discharge pipe 7 of the compressors 2a and 2b. The compressors 2a and 2b and the oil separator 17 are connected through an oil return pipe 18. A selecting means 21 for leading the oil in the oil return pipe 18 into a compressor having the less operation faculty is installed in the oil return pipe 18. Oil is returned from the oil separator 17 in priority into the compressor in which the return of oil from a low pressure suction pipe is deteriorated because of the less operation faculty. Therefore, the burn of the beating metal of the compressor having the less operation faculty can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a refrigeration system that maintains an appropriate oil level in a plurality of compressors.

(b) Conventional technology A refrigerant circuit is formed by connecting multiple compressors in parallel and sequentially connecting these compressors, condensers, pressure reducers, and evaporators, while separating oil in the high-pressure discharge pipe. At the same time, the crankcases of each compressor were connected with an oil equalizing pipe, and the oil return pipe pulled out from the oil separator was connected so that the oil would be returned to the compressor with a lower operating priority on the side to be stopped. A refrigeration system is disclosed in Japanese Utility Model Publication No. 61-36786.

(c) Problems to be Solved by the Invention In the device presented in the above publication, capacity control is performed by stopping the compressor with a lower operating priority, and oil is returned to this compressor when the lower compressor is stopped. Therefore, if the capacities of both compressors are different and the same compressor is operated at the same time, it will be difficult for oil to return to the compressor with the smaller capacity, and there is a risk that the bearing metal may seize. There was that.

An object of the present invention is to provide a refrigeration system that solves these problems.

(D) Means for Solving the Problems The present invention connects a plurality of compressors in parallel, and connects these compressors, condensers, pressure reducers, and evaporators in sequence to form a refrigerant circuit, while In a refrigeration system in which an oil separator is installed in the high-pressure discharge pipe and the crankcase of each compressor is connected with an oil equalizing pipe, one of the multiple compressors is a constant capacity compressor and the other is a variable capacity compressor. Either by using a compressor, or by using a constant capacity compressor with a plurality of compressors with different capacities, the plurality of compressors and the oil separator are connected with an oil return pipe, and the oil return pipe is connected to the oil separator. A switching means is provided to guide the oil in this pipe to the compressor having a smaller operating capacity.

(*) Effect When multiple compressors are operated at the same time, when the other variable capacity compressor or constant capacity compressor is operated at a larger capacity than one constant capacity compressor. , the switching means is operated so that oil is returned from the oil separator to the constant capacity compressor having the smaller capacity.

Conversely, when the other variable capacity compressor or constant capacity compressor is operated at a smaller capacity than one constant capacity compressor, the other variable capacity compressor or constant capacity compressor, which has a smaller capacity, The switching means is operated to return oil from the oil separator to the capacity compressor.

Example) An example of the present invention will be described based on FIG.
) is a constant capacity compressor (2a) with a rated output of 5 horsepower, and a variable capacity compressor (2b) whose operating frequency is changed by an inverter device, resulting in a minimum output of 1.6 horsepower and a maximum output of 6 horsepower. , outdoor heat exchanger (3), and gas-liquid separator (4)
), an outdoor unit having (5a) (5b) (5c)
is an indoor unit that has indoor heat exchangers (6a) (6b) (6c) and has a capacity of 2 horsepower, 4 horsepower, and 5 horsepower. The pipe (7) and the low pressure suction pipe (8) are branched and connected via the switching valves (9a) (9b), while the outdoor unit I-(1) and the indoor unit (5a) < 5b) (5c) are connected. The inter-unit piping (10) to be connected is connected to the high pressure gas pipe (11) branched to the high pressure discharge pipe (7), the low pressure gas pipe (12) branched to the low pressure suction pipe (8), and the outdoor heat exchanger. Each indoor heat exchanger (6a) (6
b) Connect (6c) to the high pressure gas pipe (11) and the low pressure gas pipe (12).
) are respectively equipped with switching valves (14g) (15a) and (14
b) It is branched and connected via (15b), (14c) and (15c), and connected to the liquid pipe (13) via a refrigerant pressure reducer (16a) (16b) (16c) such as an electric expansion valve. There is.

An oil separator (17) is installed in the high-pressure discharge pipe (7) of the compressors (2a) (2b) connected in parallel, and the oil separator (17) is connected to the compressor (2a) (2b). The main pipe (18a) of the oil return pipe (18) that returns oil has a capillary tube (
19a), and one branch pipe (18b) has this capillary (
A capillary tube (19b) having a higher resistance than 19a) is used, and the other branch tube (18c) is controlled so that the oil in the main tube (18a) is guided to the compressor (2a) or (2b) with a smaller operating capacity. A switching means (21) such as a two-way valve that is opened and closed by a signal from the means (20) is provided, and each compressor (z
The crankcases of a) and (2b) are connected with the oil equalizing pipe (22).

(23) is the discharge branch pipe (7a) of the constant capacity compressor (2a).
), (24) is this check valve (23)
A bypass pipe is connected at one end to the discharge side of the compressor (2a) and the other end is connected to the gas-liquid separator (4) and the compressor (2a). A bypass valve (25) and a capillary tube (26) are provided that are open when the compressor (2a) is stopped and until a predetermined period of time has elapsed after the compressor (2a) is started.

Next, the driving operation will be explained. When cooling all rooms at the same time, open one switching valve (9a) of the outdoor heat exchanger (3) and close the other switching valve (9b), and close the indoor heat exchanger (3).
One of the switching valves (14a) (14a) (6a) (6b) (6c)
4b) (14c) and close the other switching valve (15a).
) (15b) (15C) to open the compressor (2).
a) The refrigerant discharged from (2b) flows sequentially through the discharge pipe (7), the switching valve (9a), and the outdoor heat exchanger (3), where it is condensed and liquefied, and then passes through the liquid pipe (13) to each room. Unit (5
a) (5b) (5c) Refrigerant pressure reducer (16a) (16b
) (16c), where it is depressurized. After that,
After evaporation in each indoor heat exchanger (6a) (6b) (6c), the respective switching valves (15a) (15b) (15c), low pressure gas pipe (12), suction pipe (8), and gas-liquid separator (4) and is sucked into compressors (2a) and (2b). In this way, each indoor heat exchanger (6a) (6) acts as an evaporator.
b) All rooms are cooled at the same time in (6c).

Conversely, if you want to heat all rooms at the same time, use an outdoor heat exchanger (3)
Close one switching valve (9a) and close the other switching valve (9a).
9b) and open the indoor heat exchanger (6a) (6b) (6
Open one switching valve (14a) (14b bar 14C) of C) and open the other switching valve (15a) (15b) (15c).
By closing the compressors (2a) (2b), the refrigerant discharged from the compressors (2a) (2b) passes through the discharge pipe (<7), the high pressure gas pipe (11) in order, and then the switching valve (14a) (14b) (14c) and the indoor heat exchanger. (6a), (6b), and (6c), where the refrigerant is condensed and liquefied, and then transferred to each refrigerant pressure reducer (16a) (16b).
(16c), the liquid is combined in the liquid pipe (13), and then evaporated in the outdoor heat exchanger (3), and then the switching valve (9
b), the suction pipe (8), and the gas-liquid separator (4), and are sucked into the compressors (2a) and (2b). Each indoor heat exchanger (aa) (6b) (6c) acts as a condenser in this way
All rooms are heated at the same time.

During such simultaneous cooling operation and simultaneous heating operation, the bypass valve (25) is closed, and the constant capacity compressor m (2a) has a rated output of 5 horsepower, and the variable capacity compressor (2b) has a maximum output of 6 horsepower, respectively. being driven. Moreover, constant capacity compressor (2a
The control means (20) determines that the operating capacity of the variable capacity compressor (2b) is smaller than the operating capacity of the variable capacity compressor (2b), and the switching means (21) is closed by a signal from this means (20), and the operation is stopped. The main pipe (18a) and branch pipe (18b) of the oil return pipe (18) from the oil separator (17) to the constant capacity compressor (2a) where oil return from the gas-liquid separator (4) is poor due to its small capacity.
), the bearing metal of the constant capacity compressor (2a) will not seize up due to lack of oil.
When the oil is returned to the constant capacity compressor (2a) and the oil level rises above the level of the oil equalizing pipe (22), this oil equalizing pipe (22)
2), the oil is led to the variable capacity compressor (2b), and the oil levels of both compressors (2a) and (2b) are balanced.

Also, for example, when operating only the indoor unit (5b) to cool or heat only this one room, this indoor unit I-(
Variable capacity compressor (2b) with capacity corresponding to 4 horsepower of 5b)
) is in operation, and the constant capacity compressor (2a) is stopped. The switching means (21) is closed by a signal issued from the control means (20) upon detection of such an operation stop state, and the main pipe (18a) of the oil return pipe (18) is switched from the oil separator (17) to the oil return pipe (18) in the same way as described above. , a constant capacity compressor (
The oil is returned to 2a), so that the bearing metal etc. will not seize due to lack of oil at the start of operation. Then, as described above, oil is led to the variable capacity compressor (2b) via the oil equalizing pipe (22), and the oil levels of both compressors (2a) and (2b) are balanced. Moreover, during such indoor operation, the bypass valve (25)
opens and the discharge branch pipe (7a) of the constant capacity compressor (2a)
The pressure is released through the capillary tube (26) so that the pressure of the refrigerant in the compressor does not become high, and the check valve (23) controls the discharge refrigerant pressure of the variable capacity compressor (2b) to the discharge branch pipe (7a).
Therefore, the constant capacity compressor (2a) is smoothly started by opening the internal discharge vanes.

Such activation is performed when transitioning from one-room operation to two-room operation, and furthermore, to the above-mentioned all-room operation, but the bypass valve (2
5) is opened until a predetermined time has elapsed after the constant capacity compressor (2a) is started, and a part of the refrigerant discharged from this compressor (2a) is guided to the low pressure side via the bypass pipe (24). After reducing the output of the 5 horsepower constant capacity compressor (2a) to 2 horsepower and reducing the capacity of the variable capacity compressor (2b) to 3 horsepower to prevent the output from increasing rapidly, gradually After increasing the capacity of this compressor (2b),
At the same time as closing the bypass valve (25), the capacity of the variable capacity compressor (2b) was lowered again to 3 horsepower to prevent a sudden increase in output, and then the capacity of this compressor (2b) was gradually increased. By doing so, the output will not fluctuate suddenly when transitioning from independent operation of the variable capacity compressor m (2b) to simultaneous operation of the variable capacity compressor (2b) and constant capacity compressor (2a). .

In addition, when simultaneously cooling two units and heating one room, open one switching valve (9a) of the outdoor heat exchanger (3) and close the other switching valve (9b), and One switching valve (L4b) of the indoor unit (5b) (5c)
) (14c) and close the other switching valve (15b) (
15c) and open one switching valve (14a) of the heating indoor unit (5a), and also open the other switching valve (14a).
5a), a part of the refrigerant discharged from the compression Ja (2a) and (2b) sequentially passes through the discharge pipe (7) and the switching valve (9a) and flows to the outdoor heat exchanger (3), while the remaining refrigerant is an indoor unit (5a) that heats through a high-pressure gas pipe (11).
) to the indoor heat exchanger (6b), and is condensed and liquefied in this indoor heat exchanger (68) and outdoor heat exchanger (3). )(3
) The refrigerant condensed and liquefied passes through the liquid pipe (13) to the refrigerant pressure reducer (16b) (16c) of the indoor unit (5b) (5c).
), then the respective indoor heat exchangers (6b) (6c
), and then each switching valve (15b) (15
c), are merged with the low pressure gas pipe (12), and are connected to the suction pipe (8).
), gas-liquid separator (4) and compressor (2a) (2b
) is inhaled. In this way, the indoor heat exchanger (6a) acting as a condenser heats the room, and the other indoor heat exchangers (6b) and (6c) acting as evaporators cool the two rooms.

During such simultaneous heating and cooling operation, the heating indoor unit (
5a) has an operating capacity of 2 horsepower and an indoor unit that is cooling (
5b) Compare the total operating capacity of (5c) with 9 horsepower, and adjust the constant capacity compressor to correspond to the larger 9 horsepower.
The compressor a) is operated at 5 horsepower, and the variable capacity compressor (2b) is operated at 4 horsepower. In this way, the control means (20) determines that the operating capacity of the variable capacity compressor (2b) is smaller than the operating capacity of the constant capacity compressor (2a), and the control means (20)
) is opened by a signal from the oil separator (17) to the variable capacity compressor (2b), which has poor oil return from the gas-liquid separator (4) due to its small operating capacity. By returning oil through the main pipe (18a) and branch pipe (18c) of the oil return pipe (18), the bearing metal etc. of the variable capacity compressor (2b) will not seize due to lack of oil. When the oil is returned to the variable capacity compressor (2b) and the oil level rises above the level of the oil equalizing pipe (22), this oil equalizing pipe (22)
), the oil is led to the constant capacity compressor (2a), and the oil levels in both compressors (2a) and (2b) are balanced.

Note that, unlike the above embodiment, the resistance of the capillary tube (19a) is made smaller than that of the capillary tube (19b).
may be provided in the branch pipe (18c) of the oil return pipe (18), and the switching means 21) may be provided in the branch pipe (18b).

Also, unlike the above embodiment, if the variable capacity compressor (2b) is replaced with a 6 horsepower constant capacity compressor, when the indoor units (5a) and (5b) are operated simultaneously, the compressor (2b)
At the same time, the switching means (21) is closed and the oil is returned to the compressor (2a). When the indoor unit (5c) is operating independently, the compressor (2a) is operated independently and the switching means (21) is closed. It is opened to return oil to the compressor (2b), and when indoor units <5a, (5b, and 5c) are operated simultaneously, both compressors (2a) and (2b) are operated simultaneously, and the switching means (21) is closed. The oil should be returned to the compressor @ (2a) which has a small capacity.

FIG. 2 shows another embodiment of the present invention, which differs from the above embodiment in that the compressor (2a) is replaced by a variable capacity compressor (2b).
In addition, a capillary tube having the same resistance as the switching means (21a) (21b) consisting of two-way valves is installed in the branch pipes (18b) (18c) of the oil return pipe (18), respectively. 27a) (27b),
The same reference numerals as in FIG. 1 are used to omit detailed explanation. In this case, when the number of operating indoor units (5a) (5b) < 5c) is small, only one Yt direction variable force compressor (2a) is operated and the switching means (21b) is operated by a signal from the control means (20). The oil return pipe (1) is connected from the oil separator (17) to the other compressor (2b), which
The oil is returned through the branch pipe (18c) of 8), and when the number of operating indoor units (5a) (5b) (5c) increases and both compression INs (2a and 2b) are operated, the oil is returned to both compressors ( 2
a) Comparing the operating capacities of (2b), for example, if the capacity of the compressor (2a) is smaller, the switching means (21a)
) is opened to allow oil to be returned to the compressor (2a) from the oil separator (17) through the branch pipe (18b) of the oil return pipe (18).

In both of the above embodiments, the inter-unit piping (10) is composed of three refrigerant pipes: a high-pressure gas pipe (11), a low-pressure gas pipe (12), and a liquid pipe (13). With a simple circuit configuration using a heat exchanger, simultaneous cooling and heating operations of multiple indoor units as well as simultaneous cooling and heating operations can be freely selected and performed with any indoor unit. During simultaneous cooling and heating operation, the indoor heat exchanger that acts as a condenser and the indoor heat exchanger that acts as an evaporator are connected in series, so efficient operation can be performed by heat recovery. It is not limited to only circuits.

(G) Effects of the Invention The present invention connects a plurality of compressors connected in parallel and an oil separator provided in a high-pressure discharge pipe through an oil return pipe, and
This oil return pipe is equipped with a switching means to guide the oil in this pipe to the compressor with a smaller operating capacity, so priority is given to the compressor that has a lower operating capacity and has poor oil return from the low-pressure suction pipe. As a result, oil is returned from the oil separator, which prevents burnout such as seizure of the bearing metal of compressors with low operating capacity. By guiding oil to the larger compressors through oil equalizing pipes, the oil levels in each compressor can be balanced.

[Brief explanation of the drawing]

FIG. 1 is a refrigerant circuit diagram of a refrigeration system showing one embodiment of the present invention, and FIG. 2 is a refrigerant circuit diagram of a refrigeration system showing another embodiment of the invention. (2a) (2b) = Compressor, (7) ... High pressure discharge pipe, (17) ... Oil separator, (1B) ... Oil return pipe, (21) (21a) (21b>. ...Switching means.

Claims (2)

[Claims] (1) Connect multiple compressors in parallel, and connect these compressors, condensers, pressure reducers, and evaporators in sequence to form a refrigerant circuit, and install an oil separator in the high-pressure discharge pipe. In a refrigeration system in which the crankcase of each compressor is connected by an oil equalizing pipe, at least one of the plurality of compressors is a variable capacity compressor, and the plurality of compressors and the oil separator are connected to each other using an oil equalizing pipe. A refrigeration system characterized in that the oil return pipe is connected with a return pipe, and the oil return pipe is provided with a switching means for guiding the oil in the pipe to a compressor having a smaller operating capacity. (2) Connect multiple compressors in parallel, and connect these compressors, condensers, pressure reducers, and evaporators in sequence to form a refrigerant circuit, and provide an oil separator in the high-pressure discharge pipe. In a refrigeration system in which the crankcase of each compressor is connected with an oil equalizing pipe, a plurality of constant capacity compressors with different capacities are used for the plurality of compressors and the oil separator is connected to the oil return system. A refrigeration system characterized in that the oil return pipe is connected by a pipe, and the oil return pipe is provided with a switching means for guiding the oil in the pipe to a compressor having a smaller operating capacity.