EP3034964A1

EP3034964A1 - Compressor unit, compressor and refrigerant circuit

Info

Publication number: EP3034964A1
Application number: EP15199445.6A
Authority: EP
Inventors: Takeshi Takeda; Kenichi Murakami; Hitonobu SATO
Original assignee: Mitsubishi Heavy Industries Ltd
Current assignee: Mitsubishi Heavy Industries Thermal Systems Ltd
Priority date: 2014-12-19
Filing date: 2015-12-11
Publication date: 2016-06-22
Also published as: JP6508814B2; JP2016118317A

Abstract

A compressor unit (5) includes a first pipe (31) that is connected below an oil level (S1) of oil (L) stored inside a compressor (4) on an outer surface of the compressor (4), a second pipe (32) that is connected above the oil level (S1) on the outer surface of the compressor (4), a tank (33) to which the first pipe (31) and the second pipe (32) are connected, and an oil detecting sensor (35) that is mounted on the tank (33) to detect an oil level (S2) and is mounted below the oil level (S2).

Description

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a compressor unit, a compressor and a refrigerant circuit, those of which prevent a malfunction of a compressor provided in cold heat equipment.

Description of Related Art

For example, cold heat equipment such as a cooling unit which is installed in a store or the like has a condensing unit in which a compressor, an electric motor, a condenser and the like are mounted on the same frame and unitized as an outdoor unit.
There are various types of evaporator units (unit coolers, showcase coolers and the like) combined with the condensing unit, for individual requirements such as their numbers and shapes.
For example, as the number of the evaporator units and the lengths of the connecting pipes change, the refrigerator oil (lubricant) is retained in the evaporator units and the connecting pipes, and there is a possibility of causing an oil level drop in the compressor. Further, there is a possibility of a malfunction caused by a shortage of oil occurring in the compressor.
Patent Literature 1 discloses a refrigeration unit that separates and recovers the refrigerator oil mixed in the refrigerant gas discharged from a scroll compressor in a cooling unit that includes the scroll compressor. In the refrigeration unit, a technique for eliminating poor lubrication by detecting that an evaporation temperature is a predetermined freezing temperature or lower and by sucking the separated and recovered refrigerator oil to the scroll compressor using a pressure difference is described.

[Patent Literature]

[Patent Literature 1]

Japanese Unexamined Patent Application, First Publication No. 2012-247105

SUMMARY OF THE INVENTION

However, in the invention described in Patent Literature 1, an amount of the oil level of the refrigerator oil in the compressor cannot be checked. Therefore, in some cases, it is difficult to reliably fix poor lubrication.
The present invention provides a compressor unit which can be mounted on a compressor of cold heat equipment and can prevent a malfunction of the compressor caused by a shortage of oil from occurring, a compressor and a refrigerant circuit.
According to a first aspect of the present invention, a compressor unit includes a first pipe that is connected below an oil level of oil stored inside a compressor on an outer surface of the compressor; a second pipe that is connected above the oil level of the compressor on the outer surface of the compressor; a tank to which the first pipe and the second pipe are connected; and an oil detecting sensor that is mounted on the tank to detect the oil level of the oil stored inside the tank and is mounted below the oil level of the tank.
According to this configuration, the oil is introduced into the tank via the first pipe, the pressure of the gas in the compressor and the pressure of the gas in the tank are equalized by the second pipe, and an oil level of the same height as the oil level stored inside the compressor is formed in the tank. By detecting the oil level formed in the tank by referring to the oil detecting sensor, it is possible to check the state of the oil level of the oil stored inside the compressor. By checking the oil level in the compressor, it is possible to prevent a malfunction of the compressor caused by a shortage of the oil.
The compressor unit may further include a first supply pipe and a second supply pipe connected to the compressor from a supply source of the oil, and a valve configured to open and close the second supply pipe.
According to this configuration, by operating the valve to supply the oil from the supply source of the oil depending on the checked height of the oil level in the compressor, it is possible to eliminate the shortage of oil in the compressor.
The compressor unit may further include a control unit configured to control the valve, and the control unit may perform control of closing the valve when the oil detecting sensor detects the oil, and opening the valve when the oil detecting sensor does not detect the oil.
According to this configuration, since the control unit performs the control of the valve depending on the state of the oil level, the oil stored in the supply source of the oil can be automatically supplied to the compressor.
According to a second aspect of the present invention, a compressor includes any one of the above-described compressor units.
According to a third aspect of the present invention, a refrigerant circuit includes the above-described compressor.
According to the above-described compressor unit, compressor and refrigerant circuit, it is possible to prevent a malfunction of the compressor from occurring due to the oil shortage.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating cold heat equipment according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of a compressor and an oil sump of the cold heat equipment according to the embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, a cooling unit 1 which is cold heat equipment of an embodiment of the present invention will be described in detail with reference to the drawings.
As illustrated in FIG. 1, the cooling unit 1 of this embodiment has a refrigerant circuit that includes a refrigerant pipe (a gas pipe 7 and a liquid pipe 8). The refrigerant circuit is provided with an outdoor unit 2 (a condensing unit) and an indoor unit 3 (an evaporator unit) that are connected to each other. Further, as long as the indoor units 3 are sequentially connected in parallel to the outdoor unit 2, the number of indoor units 3 may be increased.
The outdoor unit 2 is provided with a compressor 4 that compresses the refrigerant gas introduced through the gas pipe 7, a compressor unit 5 mounted on the compressor 4 for use, an oil separator 9 that separates a lubricant L (refrigerator oil) contained in the refrigerant gas discharged from the compressor 4, a condenser 10 (an outdoor heat exchanger) that performs heat exchange between the outdoor air and the refrigerant to condense the refrigerant, and a control unit 11 as main constituent elements. Furthermore, the outdoor unit 2 has an accumulator 12 (a liquid separator) that performs the gas-liquid separation of the refrigerant gas supplied to the compressor 4 via the gas pipe 7.
The indoor unit 3 is provided with an evaporator 13 (an indoor heat exchanger) that performs heat exchange between the indoor air and the refrigerant to evaporate the refrigerant, and an expansion valve 14 as main constituent elements. The expansion valve 14 is a valve that depressurizes the high-temperature and high-pressure liquid refrigerant introduced from the condenser 10 via the liquid pipe 8 into an easily evaporable state.
The accumulator 12 is a pressure container which is provided upstream from a suction pipe 15 of the compressor 4 (a gas pipe 7 between the evaporator 13 and the compressor 4). As the accumulator 12, it is possible to adopt a structure in which a liquid refrigerant is accumulated in the container and only the refrigerant converted into a steam is returned to the compressor 4.
The compressor 4 compresses the refrigerant gas introduced in a low-pressure state and discharges the refrigerant gas into the oil separator 9.
As shown in FIG. 2, the compressor 4 has a sealed structure in which a scroll type compression mechanism 17, an electric motor 18 configured to drive the scroll type compression mechanism 17, and a rotary shaft 19 (a drive shaft) configured to transmit the driving force generated by the electric motor 18 to the scroll type compression mechanism 17 are housed within the housing 20.
The electric motor 18 includes a rotor 21 and a stator 22. The electric motor 18 drives the rotary shaft 19 by electrical energy.
The scroll type compression mechanism 17 includes a fixed scroll 24 and a turning scroll 25. The electric motor 18 and the scroll type compression mechanism 17 are connected to each other via the rotary shaft 19.
An upper end of the rotary shaft 19 is rotatably fixed to the housing 20 via a sub-bearing 26. A lower end of the rotary shaft 19 is rotatably fixed to a frame 28 of the housing 20 via a main bearing 27.
When the electric motor 18 drives the rotary shaft 19, the turning scroll 25 of the scroll type compression mechanism 17 rotates. The compressor 4 performs lubrication of sliding portions in the compressor 4 using the lubricant L. The lubricant L is stored at the bottom of the housing 20. That is, the bottom of the housing 20 of the compressor 4 functions as an oil sump in which the lubricant L configured to lubricate the scroll type compression mechanism 17 or the like is stored. When the lubricant L is stored in the housing 20, the oil level S1 is formed.
Although it is not illustrated, an oil passage is formed inside the rotary shaft 19 in an axial direction. The lubricant L stored at the bottom of the housing 20 is supplied to the sliding portions such as the main bearing 27 via the oil passage formed in the rotary shaft 19.
The oil separator 9 is provided downstream from the compressor 4. The oil separator 9 separates the lubricant L from the refrigerant gas in which the lubricant L fed through a discharge pipe 30 (the gas pipe 7 between the compressor 4 and the condenser 10) is mixed, due to a centrifugal force or the like. The oil separator 9 has a cylindrical shape having a closed top and a closed bottom. The oil separator 9 is capable of storing the separated lubricant L. That is, it is possible to allow the oil separator 9 to function as a supply source of the lubricant L.
Next, the details of the compressor unit 5 that can be additionally installed in the cooling unit 1 will be described.
The compressor unit 5 has a first pipe 31 that is connected below an oil level S1 of the lubricant L stored inside the compressor 4 on the housing 20 of the compressor 4, a second pipe 32 that is connected above the oil level S1, and an oil sump 33 (tank) that is connected to the housing 20 of the compressor 4 via the first pipe 31 and the second pipe 32.
The first pipe 31 is a pipe for feeding the lubricant L stored inside the compressor 4 to the oil sump 33. The first pipe 31 is connected to an outer surface 20a of the housing 20 of the compressor 4. The first pipe 31 is connected to the bottom of the housing 20 of the compressor 4 so that the lubricant L is fed to the oil sump 33 as long as at least a small amount of the lubricant L is stored inside the housing 20 of the compressor 4.
The second pipe 32 is connected to the outer surface 20a of the housing 20 of the compressor 4. The second pipe 32 is connected to a position at which the lubricant L does not flow into the second pipe 32 even when the oil level S1 is at its highest, based on a total amount and the like of the lubricant L used in the compressor 4.
The oil sump 33 is a container capable of storing the lubricant L and has a sealed structure. The first pipe 31 is connected to the bottom of the oil sump 33. The second pipe 32 is connected to an upper portion of the oil sump 33.
A first oil detecting sensor 35 and a second oil detecting sensor 36 configured to detect an oil level S2 of the lubricant L stored in the oil sump 33 are mounted on upper and lower portions of the oil sump 33. The first oil detecting sensor 35 and the second oil detecting sensor 36 are detectors capable of detecting the presence or absence of the lubricant L at the locations at which they are installed. The first oil detecting sensor 35 and the second oil detecting sensor 36 are configured to transmit a signal to the control unit when the lubricant L touches the sensor surface. That is, the first oil detecting sensor 35 and the second oil detecting sensor 36 are connected to the control unit 11. The control unit 11 performs control depending on signals received from the first oil detecting sensor 35 and the second oil detecting sensor 36.
The first oil detecting sensor 35 is disposed based on a total amount of the lubricant L used in the compressor 4 and a desired control method. Specifically, when the amount of lubricant L stored in the compressor 4 is an appropriate amount, the first oil detecting sensor 35 is disposed below the oil level S2 formed in the oil sump 33. That is, the first oil detecting sensor 35 is disposed to detect the lubricant L when the amount of lubricant L stored in the housing 20 of the compressor 4 is an appropriate amount.
The second oil detecting sensor 36 is disposed above the first oil detecting sensor 35, based on the total amount of lubricant L used in the compressor 4 and a desired control method. Specifically, the second oil detecting sensor 36 is disposed above the oil level S2 formed in the oil sump 33 when the amount of lubricant L stored in the compressor 4 is an appropriate amount. That is, the second oil detecting sensor 36 is disposed not to detect the lubricant L when the amount of the lubricant L stored in the housing 20 of the compressor 4 is an appropriate amount.
As shown in FIG. 1, the compressor unit 5 includes a first supply pipe 37 and a second supply pipe 38 that feed the lubricant L stored in the oil separator 9 to the compressor 4. First end portions of the first supply pipe 37 and the second supply pipe 38 are connected to the lower portion of the container of the oil separator 9. Second end portions of a side opposite to the first end portions of the first supply pipe 37 and the second supply pipe 38 are connected to the upper portion of the housing 20 of the compressor 4.
The first supply pipe 37 and the second supply pipe 38 may be formed independently of each other, and as shown in FIG. 1, the first supply pipe 37 and the second supply pipe 38 may diverge in the middle.
Throttle portions 39 such as capillary tubes are provided in the first supply pipe 37 and the second supply pipe 38. A first solenoid valve 41 configured to open and close the first supply pipe 37 is provided in the first supply pipe 37. That is, by setting the first solenoid valve 41 to an open state, the lubricant L flowing through the first supply pipe 37 is allowed to flow, and by setting the first solenoid valve 41 to a closed state, the lubricant L flowing through the first supply pipe 37 can be stopped.
A second solenoid valve 42 similar to the first solenoid valve 41 provided in the first supply pipe 37 is provided in the second supply pipe 38.
The first solenoid valve 41 and the second solenoid valve 42 are connected to the control unit 11. That is, the first solenoid valve 41 and the second solenoid valve 42 can be opened and closed based on the signals transmitted from the control unit 11.
When the first oil detecting sensor 35 and the second oil detecting sensor 36 detect the lubricant L, that is, when an amount of the lubricant L exceeding the position of the second oil detecting sensor 36 is connected, the control unit 11 sets the second solenoid valve 42 to a closed state. That is, when the second oil detecting sensor 36 detects the lubricant L, the control unit 11 determines that the oil level S1 in the compressor 4 is also sufficiently stored, and does not feed the lubricant L from the oil separator 9 that is a supply source of the lubricant L.
When only the first oil detecting sensor 35 detects the lubricant L, that is, when the oil level S2 is located at a position between the first oil detecting sensor 35 and the second oil detecting sensor 36, the control unit 11 sets the second solenoid valve 42 to a closed state. That is, when only the first oil detecting sensor 35 detects the lubricant L, the control unit 11 determines that the oil level S1 in the compressor 4 is appropriate, and does not feed the lubricant L from the oil separator 9 that is a supply source of the lubricant L.
When neither the first oil detecting sensor 35 nor the second oil detecting sensor 36 detects the lubricant L, that is, when an amount of the lubricant L that does not reach the position of the first oil detecting sensor 35 is connected, the control unit 11 sets the second solenoid valve 42 to an open state. That is, when the first oil detecting sensor 35 does not detect the lubricant L, the control unit 11 determines that the oil level S1 of the lubricant L in the compressor 4 has dropped and the lubricant L is insufficient, and feeds the lubricant L from the oil separator 9 that is a supply source of the lubricant L.
In addition, the first solenoid valve 41 is normally in an open state. That is, the lubricant L stored in the oil separator 9 is supplied to the inside of the compressor 4 via the first supply pipe 37 in a normal state. A control method of the first solenoid valve 41 is not limited thereto, and when the amount of lubricant L is determined to be sufficient, control of closing the first solenoid valve 41 may be performed. For example, when the first oil detecting sensor 35 and the second oil detecting sensor 36 detect the lubricant L, that is, when an amount of the lubricant L exceeding the position of the second oil detecting sensor 36 is connected, control of closing the first solenoid valve 41 may be performed.
The compressor unit 5 can be mounted on the general-purpose compressor 4 provided in the existing cold heat equipment. The oil sump 33 may be mounted to be integrated with the compressor 4 using a predetermined bracket 43. When the oil sump 33 is mounted to be integrated with the compressor 4, it is possible to prevent the first pipe 31 and the second pipe 32 from being deteriorated by vibration of the compressor 4.
Next, the operation of the compressor unit 5 of the present embodiment will be described.
When the lubricant L is stored inside the housing 20 of the compressor 4 and the oil level S1 is formed, the lubricant Lis introduced into the oil sump 33 via the first pipe 31. Furthermore, the pressure of the gas in the compressor 4 and the pressure of the gas in the oil sump 33 are equalized by the second pipe 32, and the oil level S2 of the same height as the oil level S1 stored inside the compressor 4 is formed in the oil sump 33.
For example, when the lubricant L is retained in the evaporator 13, the refrigerant pipe or the like, and a drop of the oil level S1 of the lubricant L stored inside the compressor 4 occurs, the first oil detecting sensor 35 does not detect the lubricant L. Thus, the control unit 11 sets the second solenoid valve 42 to an open state. When the second solenoid valve 42 is set to an open state, the lubricant L stored in the oil separator 9 is fed into the housing 20 of the compressor 4, and the oil level S1 of the lubricant L rises. When the lubricant L in the compressor 4 is sufficient, the first oil detecting sensor 35 detects the lubricant L and the control unit 11 closes the second solenoid valve 42, and the lubricant L is not supplied via the second supply pipe 38.
According to the above-described embodiment, the lubricant L is introduced into the oil sump 33 via the first pipe 31, the pressure of the gas in the compressor 4 and the pressure of the gas in the oil sump 33 are equalized by the second pipe 32, and the oil level S2 of the same height as the oil level S1 stored inside the compressor 4 is formed in the oil sump 33. By detecting the oil level S2 formed in the oil sump 33 with reference to the first oil detecting sensor 35, it is possible to check the state of the oil level S1 of the lubricant L stored inside the compressor 4. By checking the oil level S1 in the compressor 4, it is possible to prevent a malfunction of the compressor 4 caused by the shortage of lubricant.
Moreover, by operating the second solenoid valve 42 to supply the lubricant L from the oil separator 9 serving as the supply source of lubricant L depending on the checked height of the oil level S1 in the compressor 4, it is possible to eliminate the shortage of oil in the compressor 4.
Further, since the control unit 11 performs the control of the second solenoid valve 42 depending on the state of the oil level S2, it is possible to automatically supply the lubricant L stored in the oil separator 9 to the compressor 4.

[Modified example of embodiment of present invention]

Although the compressor unit 5 has been described using the cooling unit 1 as the cold heat equipment in the above-described embodiment, the compressor unit 5 of the present embodiment is also applicable to other types of cold heat equipment, without being limited to the cooling unit 1. The compressor unit 5 of this embodiment, for example, can also be applied to an air conditioner that reverses the flow of the refrigerant using a switching valve such as a four-way valve.
Also, instead of the oil separator 9, a receiver (a liquid receiver) that temporarily stores the lubricant L can also be adopted. That is, as long as a container functions as a supply source of the lubricant L, anything can be appropriately adopted, without being limited to the oil separator 9.
Also, although the compressor 4 is disposed with the scroll type compression mechanism 17 located in a vertically lower part in the above-described embodiment, the compressor 4 may be disposed with the scroll type compression mechanism 17 located in a vertically upper part.

[Industrial Applicability]

According to the above-described compressor unit, the compressor and the refrigerant circuit, it is possible to prevent a malfunction of the compressor from occurring due to a shortage of oil.

Claims

A compressor unit (5) comprising:
a first pipe (31) that is connected below an oil level (S1) of oil stored inside a compressor (4) on an outer surface of the compressor (4);

a second pipe (32) that is connected above the oil level (S1) of the compressor (4) on the outer surface of the compressor (4);

a tank (33) to which the first pipe (31) and the second pipe (32) are connected; and

an oil detecting sensor (35) that is mounted on the tank (33) to detect the oil level of the oil stored inside the tank (33), and is mounted below the oil level (S1) of the tank (33).
The compressor unit (5) of claim 1, further comprising:
a first supply pipe (37) and a second supply pipe (38) connected to the compressor (4) from a supply source of the oil; and

a valve (42) configured to open and close the second supply pipe (38).
The compressor unit (5) of claim 2, further comprising:
a control unit (11) configured to control the valve (42),

wherein the control unit (11) performs control of closing the valve (42) when the oil detecting sensor (35) detects the oil, and opening the valve (42) when the oil detecting sensor (35) does not detect the oil.
A compressor (4) comprising the compressor unit (5) according to any one of claims 1 to 3.
A refrigerant circuit (1) comprising the compressor (4) according to claim 4.