JPH03122460A - Operating controller for refrigerating machine - Google Patents

Abstract

PURPOSE:To effectively avoid a risk of oil shortage at start-up for improving the reliability by a method wherein a bypass is provided parallel with an oil return line so as to bypass a flow restriction device and opened during start-up of a compressor for a specified time period. CONSTITUTION:An operating controller 15 controls a bypass on-off valve 35 to close it during normal operation, so that a small amount of gas refrigerant containing oil is returned from an oil separator to the suction side of a compressor 1 through an oil return line 33. On the other hand, the bypass valve 35 is controlled to be opened for a specified time period during start-up of the compressor 1 to expand the passage, so that a large amount of gas refrigerant containing oil is returned from the oil separator to the suction side of the compressor 1 through an oil return line 33 and an oil return bypass line 34. Therefore, the compressor 1 is started with avoiding the oil shortage in the compressor 1, and such troubles as seizure of the compressor 1 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an operation control device for a refrigeration system equipped with an oil return passage, and particularly relates to measures for improving the operation function at startup.

(Prior Art) Conventionally, as disclosed in, for example, Japanese Unexamined Patent Application Publication No. 63-73059, a pressure equalizing bypass path is provided from the discharge side of the compressor to the suction side through a pressure reducing mechanism to bypass the refrigerant. By opening the pressure equalization bypass passage and equalizing the high and low pressures when the compressor is started, the load at the start of the compressor is reduced, and an oil separator is installed on the discharge side of the compressor to separate the oil. By providing an oil return passageway that returns oil from the compressor to the suction side of the compressor, refrigerant mixed with oil is returned to the compressor while the equipment is in operation, thereby preventing accidents such as seizure due to oil leaking into the compressor. is a known technique.

(Problem to be Solved by the Invention) However, even if the oil is returned to the compressor from the oil separator as in the above-mentioned conventional system, there is a risk that it may not necessarily be possible to prevent water from rising when the compressor is started. There is.

In other words, when the compressor is started, the high pressure and low pressure are usually equalized, and the differential pressure between the high and low pressures is small, so the flow rate in the oil return passage is small, and the oil is not sufficiently supplied to the compressor through the oil return passage. It is difficult to return to the suction side. Therefore, depending on the type and operating conditions of the compressor, such as compressors with inverters whose operating capacity is controlled to be small when the compressor is started, oil may rise in the compressor and cause seizures due to lack of oil. There is.

The present invention has been made in view of the above, and its first object is to reduce the amount of oil at the time of starting the compressor by providing a means for increasing the flow rate of the oil return passage at the time of starting the compressor. The objective is to effectively prevent uplinks and improve reliability.

A second object of the present invention is to provide a means for performing an oil return function when the compressor is started and a pressure equalization function when the compressor is stopped. The purpose is to eliminate the need for a bypass road.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention includes a compressor (1) and a Oil separator (2) that separates oil in the discharged refrigerant
), and an oil return passage (33) that returns oil from the oil separator (2) to the suction side of the compressor (1) via a flow restriction mechanism (32).
).

The oil return passageway (33) is connected to the flow rate restricting mechanism (
An oil return bypass path (34) is provided in parallel to bypass the oil return bypass path (32), and a bypass opening/closing valve (35) is provided to open and close the oil return bypass path (34).

Furthermore, an operation control means (15) is provided for controlling the bypass on-off valve (35) to be opened for a predetermined period of time when the compressor (1) is started.

As shown in FIG. 1 (including the broken line part), the second solution means, in addition to the first solution means, includes a bypass throttle mechanism (36
).

(Function) With the above configuration, in the invention of claim (1), the operation control means (15) controls the bypass on-off valve (
35) is controlled to close, and a small amount of gas refrigerant mixed with oil returns from the oil separator (4) to the suction side of the compressor (1) via the oil return passage (33). At startup, the bypass on-off valve (35) is controlled to open for a certain period of time, and the expansion of the passage causes a large amount of gas refrigerant mixed with oil to flow from the oil separator (4) to the oil return passage (33) and the oil return bypass passage. (34) and is returned to the suction side of the compressor (1).

Therefore, the compressor (1) is started without causing an oil shortage in the compressor (1), and accidents such as seizure are prevented.

In the invention of claim (2), in addition to the effect of the invention of claim (1), it is possible to equalize high pressure and low pressure by opening the bypass on-off valve (35), and the pressure equalization bypass Since there is no need to provide a separate path, the effect of the invention of claim (1) can be obtained without increasing costs.

(Example) Hereinafter, an example of the present invention will be described based on the drawings from FIG. 2 onwards.

FIG. 2 shows a refrigerant piping system of a multi-type air conditioner according to an embodiment of the present invention, in which (A) is an outdoor unit, (B) -
(F) is an indoor unit connected in parallel to the outdoor unit (A). Inside the outdoor unit (A),
Compressor (1) whose capacity is adjusted by an inverter (2)
and an oil separator (4) that separates oil from the gas discharged from the compressor (1), and an oil separator (4) that switches as shown in the solid line in the figure during cooling operation and as shown in the broken line in the figure during heating operation. a road switching valve (5), an outdoor heat exchanger (6) that serves as a condenser during cooling operation and an evaporator during heating operation, and two outdoor fans (6a) attached to the outdoor heat exchanger (6); (
6b), and an outdoor electric expansion valve (8) that adjusts the refrigerant flow rate during cooling operation and throttles the refrigerant during heating operation;
A receiver (9) for storing liquefied refrigerant and an accumulator (10) for removing liquid refrigerant from suction refrigerant are built-in as main devices, and each of the devices (1) to (1)
0) are connected to each other through refrigerant communication pipes (11) so that refrigerant can flow therethrough. In addition, the above indoor units (B) to (F)
have the same configuration, and each has an indoor heat exchanger (12) that serves as an evaporator during cooling operation and a condenser during heating operation.
and a fan (12a), . . . , and a liquid refrigerant branch pipe (11, a) of the indoor heat exchanger (12), .
), ... are equipped with an indoor electric expansion valve (13) that adjusts the refrigerant flow rate during heating operation and throttles the refrigerant during cooling operation.
,... are interposed respectively, and a manual closing valve (17
).

(17) and is connected to the outdoor unit (A) by a connecting pipe (1lb). In other words, each of the above-mentioned devices is connected by refrigerant piping (11) so that refrigerant can flow, and a main refrigerant circuit (14) is configured to release heat obtained through heat exchange with outdoor air to indoor air. It is configured.

Next, (33) connects the oil separator (4) to the compressor (1).
An oil return passage for returning oil to the oil return passage (
33) is provided with an oil return capillary tube (32).

In addition, (11e) connects the discharge pipe and the liquid pipe side to the discharge gas (
A bypass path for heating overload control connected to enable bypass of (hot gas), the bypass path (lie) including:
An auxiliary heat exchanger (22) installed in a common air passage with the outdoor heat exchanger (6), a capillary tube (28), and an electromagnetic shut-off valve (24) that opens when the refrigerant is at high pressure are connected in series and connected in sequence to the outdoor heat exchanger (6). It is connected in parallel with the exchanger (6),
At all times during cooling operation, and when high pressure rises excessively during heating operation, the electromagnetic on-off valve (24) is turned on or opened, and part of the discharged gas is transferred from the main refrigerant circuit (14) to the heating overload control bypass path. (11e) is bypassed. At this time, a part of the discharged gas is transferred to the auxiliary heat exchanger (22
) to support the capacity of the outdoor heat exchanger (6), and the capillary tube (28) to condense the outdoor heat exchanger (
The pressure loss on the 6) side is balanced.

Furthermore, (11g) is the heating overload binox road (
11e) is a liquid injection bypass path that connects the liquid refrigerant side piping of 11e) and the suction line of the main refrigerant circuit (14) to adjust the degree of superheating of the suction gas during heating and cooling operation, the bypass path (11g) has a compressor (
An injection solenoid valve (29) that opens and closes in conjunction with the on/off of 1) and a capillary tube (30) are interposed.

In addition, (31) cools the suction refrigerant through heat exchange between the suction refrigerant in the suction pipe (11) and the liquid refrigerant in the liquid pipe (11), thereby increasing the degree of superheating of the refrigerant in the connecting pipe (llb). (SP) is the service port, (GP) is the gauge boat.

In addition, the device is equipped with many sensors (T
HI), ... are room temperature thermostats that detect each indoor temperature, (TH2), ... and (TH3) ... are the liquid side and gas side pipes of the indoor heat exchanger (12), ..., respectively. (TH4) is a discharge pipe sensor that detects the temperature of the discharge pipe of the compressor (1), and (TH5) is the outdoor heat exchanger (6) that detects the temperature of the refrigerant during heating operation. The defrost sensor (TH6) detects the frosting state from the outlet temperature of the suction pipe heat exchanger (
The suction pipe sensor (TH7) is placed at the air suction port of the outdoor heat exchanger (6) and detects the suction air temperature. The outside temperature sensor (Pl) is a pressure sensor that detects the low pressure of refrigerant pressure, that is, the saturation temperature equivalent to evaporation pressure, during cooling operation, and the high pressure, that is, the saturation temperature, equivalent to condensing pressure, during heating operation.
(HPS) is a high pressure switch for compressor protection.

Each of the solenoid valves and sensors described above is connected to an outdoor control unit (15) that controls the operation of the device along with each main device by a signal line either directly or via an indoor control unit (not shown), and the outdoor control unit (15) controls each device of the outdoor unit (A).

Here, as a feature of the present invention, the oil return passage (33)
An oil return bypass path (34) is provided in parallel to bypass the oil return capillary tube (32), and the oil return bypass path (34) is connected to the oil return bypass path (34). A bypass opening/closing valve (35) that opens and closes, and a bypass capillary tube (36) as a bypass throttling mechanism that throttles the flow rate of refrigerant flowing through the oil return bypass path (34) are provided.

In Fig. 2, during cooling operation of the air conditioner, the four-way switching valve (2) switches to the solid line side in the figure, and the auxiliary heat exchanger (22
) is always open, and the refrigerant compressed by the compressor (1) is condensed in the outdoor heat exchanger (6) and the auxiliary heat exchanger (22), and then passed through the connecting pipe (1 lb). It is branched and sent to each indoor unit (B) to (F). Then, in each indoor unit (B) to (F), the pressure is reduced by each indoor electric expansion valve (1, 3), etc., and the pressure is reduced by each indoor heat exchanger (1, 3), etc.
2) After being evaporated in..., they are combined and sent to the outdoor unit (A).
It returns to the gas state and is circulated so that it is sucked into the compressor (1).

On the other hand, during heating operation, the four-way selector valve (5) switches to the side shown by the broken line in the figure, and the flow of refrigerant is reversed to that during cooling operation, and the refrigerant compressed by the compressor (]) is transferred to each indoor heat source. Exchanger (1
2), . ).

Here, during operation of the air conditioner, when each of the indoor units (B) to (F) is thermo-off, the outdoor control unit (15) stops the compressor (1), while each indoor unit When at least one of the units (B) to (F) returns to the thermo-on state, the compressor (1) is controlled to restart.

The bypass on-off valve (35) is normally closed, and a small amount of gas refrigerant mixed with oil is always passed through the oil return passage (35).
33) only to the suction side of the compressor (1),
Only when the compressor (1) returns from the thermo-off state to the thermo-on state or when the compressor (1) starts up due to the start of operation of the device,
By opening the bypass on-off valve (35), a large amount of gas refrigerant mixed with Ura is passed from the oil separator (4) to the compressor (1) via the oil return passage (33) and the oil return bypass passage (34). It is designed to return to the suction side. That is, the outdoor control unit (15) has a function as an operation control means that controls the bypass on-off valve (35) to be opened only when the compressor (1) is started.

Furthermore, when the compressor (1) is stopped, the bypass on-off valve (
35) for a certain period of time to equalize high pressure and low pressure, the compressor (1)
The system is designed to prevent startup failures.

Therefore, in the invention of claim (1), since the outdoor control unit (operation control means) (15) normally controls the bypass on-off valve (35) to close, the oil separator (
4), a small amount of gas refrigerant mixed with ura is returned to the suction side of the compressor (1) via the oil return passage (33).

Here, when the compressor (1) is started, the differential pressure between high and low pressures becomes small, so for example, the inverter (
In the case of the compressor (1) whose operating capacity is adjusted by 2), since the operating capacity of the compressor (1) at startup is small (for example, a value of about 30 Hz in the above embodiment), the oil return passage ( Since the flow rate of the refrigerant is extremely reduced due to the insufficient differential pressure in the compressor (1), there is a risk of an accident such as seizure due to lack of oil in the compressor (1).

In contrast, in the present invention, when starting the compressor (1),
Since the operation control means (15) controls the bypass on-off valve (35) to open for a certain period of time, a large amount of gas refrigerant mixed with Ura flows from the oil separator (4) to the oil return passageway (33) and to the oil return passage. It will be returned to the suction side of the compressor (1) via the bypass path (34), and the compressor (]
-) lack of ura is prevented by the f-T effect, and therefore reliability and performance can be improved.

In the invention of claim 21, in the invention of claim fi+, a bypass capillary tube (36) for restricting the flow rate of the gas refrigerant is interposed in the oil return bypass path (34), so that the compressor When the ( ) is stopped, the bypass on-off valve (35) can be opened to equalize the high pressure and low pressure via the oil return bypass path (34), which eliminates the need to provide a separate hot gas bypass path for pressure equalization. Therefore, the effect of the invention of claim (1) above can be obtained without causing an increase in cost.

In addition. In the above embodiment, the compressor (4) is connected to the inverter (2).
), but the operating capacity was adjusted by
The present invention is not limited to such embodiments, but can also be applied to a type in which the capacity is adjusted by an unloader mechanism or a type without a capacity 1 withdrawal mechanism. However, in the case of using the inverter (2) as in the above embodiment, the operating capacity is small especially at startup, so the amount of oil returned is small and the compressor (1) is likely to run out of oil. 1. Therefore, the effects of the present invention can be significantly exhibited.

(Effects of the Invention) As explained above, according to the invention of claim (1), an oil return passage is provided for returning oil from the oil separator to the suction side of the compressor via a flow rate restricting mechanism, and A bypass path is provided in parallel in the passage to bypass the flow rate restricting mechanism, and this bypass path is opened for a predetermined period of time when the compressor is started, thereby effectively preventing the risk of oil shortage at the time of startup. Therefore, reliability can be improved.

According to the invention of claim (2), in the invention of claim (1), the bypass passage is provided with a bypass throttle mechanism for throttling the bypass flow rate, so that the bypass passage is increased by +1JJrJ.
The pressure equalization when the compressor is stopped at t and t is now possible, and therefore the effect of the invention of claim (1) above can be exhibited without causing an increase in cost.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention. FIG. 2 is a refrigerant piping system diagram of an air conditioner according to an embodiment of the present invention. 1 Compressor 15 Outdoor control unit (operation control means) 32 Capillary tube for oil return (flow rate throttling mechanism) 33 Oil return passage 34 Bending bypass passage 35 Bypass opening/closing valve 36 Capillary tube for bypass (bypass throttling mechanism) Compressor outdoor control Capillary tube for unit oil return (flow restriction mechanism) Oil return passage Oil return bypass passage Bypass on/off valve Capillary tube for bypass (bypass restriction mechanism)

Claims (2)

[Claims] (1) A compressor (1), an oil separator (2) that separates oil in the refrigerant discharged from the compressor (1), and an oil separator (2) that separates oil from the refrigerant discharged from the compressor (1), and a In a refrigeration system equipped with an oil return passage (33) that returns oil via a flow rate restriction mechanism (32), an oil return passage (33) is provided in parallel to the oil return passage (33) so as to bypass the flow rate restriction mechanism (32). Oil return bypass path (
34) and a bypass on-off valve (35) that opens and closes the oil return bypass path (34), and opens the bypass on-off valve (35) for a predetermined period of time when the compressor (1) is started. Operation control means to control (15
) An operation control device for a refrigeration system. (2) The air conditioner according to claim (1), wherein the oil return bypass path (34) is provided with a bypass throttle mechanism (36) that throttles the amount of bypass.