JP3387250B2 - Lubricating oil discharge structure of compressor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricating oil discharge structure for a compressor provided in a refrigerating machine or the like, and particularly for discharging the lubricating oil accumulated above the compression part after lubricating the compression part. Regarding the improvement of.

[0002]

2. Description of the Related Art Conventionally, for example, JP-A-6-28076.
In the compressor as disclosed in Japanese Patent Publication No. 8, the compressor is provided in the upper space and the motor is provided in the lower space in the casing, and the crankshaft extending upward from the motor is linked to the compressor. Then, the refrigerant sucked from the suction pipe provided on the side surface of the casing is compressed by the compression unit by the rotation of the crankshaft accompanying the driving of the motor, and thereafter, the compressed refrigerant is discharged from the discharge pipe provided at the upper part of the casing. It is like this.

Lubricating oil is stored in the bottom of the casing, and the lower end of the crankshaft is immersed in this lubricating oil. This crankshaft is provided with a pump mechanism such as a centrifugal pump at its lower end and an oil passage is formed inside, and when the compressor is driven, the lubricating oil on the bottom of the casing is removed as the crankshaft rotates. A pump mechanism pumps up the oil and supplies it to each sliding portion of the compression unit through an oil passage to perform lubrication.

[0004]

By the way, in this type of compressor, depending on the operating conditions, the lubricating oil supplied from the oil passage to the compressor to lubricate the sliding parts is collected at the bottom of the casing. Instead, it may collect on the upper side of this compression section. For example, at the time of wet operation in which the suction refrigerant is in a wet state, the mist-like lubricating oil introduced into the casing together with the suction refrigerant is introduced into the compression section together with the refrigerant without being collected in the casing bottom. Will accumulate on the upper side of the. When the lubricating oil accumulates on the upper side of the compression section in this way, the lubricating oil becomes discharge resistance of the refrigerant and causes deterioration of the compressor performance.

In order to solve such a problem, an oil recovery passage is provided to connect the upper space of the compression part, which is a high-pressure space, and the lower space of the casing, which is a low-pressure space, and the oil recovery passage lubricates the upper part of the compression part. It has been proposed to recover the oil in the lower part of the casing, and in order to increase the recovery amount of the lubricating oil in order to reliably reduce the discharge resistance of the refrigerant,
It is necessary to form the oil recovery passageway to have a relatively large diameter.

However, in such a structure, the amount of refrigerant bypass from the high pressure side to the low pressure side in the compressor is increased by the oil recovery passage, and the capacity of the compressor is reduced.

Further, in the case where two compressors are provided in parallel with the refrigerant circuit, when the lubricating oil is accumulated above the compression portion of one compressor, the lubricating oil is accumulated in the other compressor. Since there is a risk that the amount will be insufficient and sufficient lubrication will not be possible, in such a case, it is necessary to discharge the lubricating oil above the compression section of one of the compressors.

The present invention has been made in view of these points, and it is an object of the present invention to reliably discharge the lubricating oil accumulated in the space above the compression portion without causing a reduction in the capacity of the compressor. And

[0009]

In order to achieve the above object, the present invention is provided with an oil discharge pipe for discharging the lubricating oil accumulated on the upper side of the compression section to the discharge pipe, and a pressure loss is generated in the discharge pipe. By doing so, a pressure difference is generated at both ends of the oil discharge pipe, whereby the lubricating oil is discharged.

Specifically, the invention according to claim 1 is, as shown in FIG. 4, a compression portion (96) provided in a casing (95).
Compressor that compresses fluid and discharges it to the discharge pipe (25-D)
(COMP-1) is assumed. Then, between the upper space of the compression section (96) and the middle section of the discharge pipe (25-D), the compression section (9
Install the oil discharge pipe (76) for discharging the lubricating oil accumulated in the upper space of 6) to the discharge pipe (25-D). In addition, the discharge pipe (25-
D) and the oil discharge pipe (76) are connected to the pressure inside the casing (95).
The discharge pipe (25-D) is opened to the upper space of the contraction portion (96) ,
Inside the discharge pipe (25-D) rather than the pressure loss inside the oil discharge pipe (76)
The pressure loss of the discharge fluid is increased between the discharge portion of the compressor (COMP-1) and the connection portion of the oil discharge pipe (76) so that the pressure loss of the discharge fluid becomes larger .

According to a second aspect of the present invention, in the lubricating oil discharge structure for a compressor according to the first aspect, the flow direction of the discharge fluid is greater than the connecting portion of the oil discharge pipe (76) in the discharge pipe (25-D). On the upstream side of the discharge pipe (2), the flow passage area of the discharge pipe (25-D) increases as the flow rate of the fluid discharged from the compressor (COMP-1) increases.
5-D) The pressure loss means (CV-1) for changing the internal pressure loss is provided.

According to a third aspect of the present invention, in the lubricating oil discharge structure for a compressor according to the second aspect, the pressure loss means comprises:
The check valve (CV-1) has a valve body (92) that is opened by the pressure of the fluid discharged from the compressor (COMP-1). Further, a biasing force (93) is applied to the valve body (92) against the pressure of the discharge fluid.
The configuration given by

[0013]

With the above construction, the present invention provides the following actions. In the invention according to claim 1, the discharge pipe
(25-D) has a pressure loss, which causes the oil discharge pipe (7
One end of the compression section (96) connected to the upper space of 6) is in a high pressure state, while the other end of the discharge tube (25-D) connected to an intermediate section is in a low pressure state. As a result, the lubricating oil accumulated on the upper side of the compression section (96) is discharged to the discharge pipe (25-D) by the oil discharge pipe (76). Therefore, it is possible to prevent a large amount of lubricating oil from accumulating on the upper side of the compression section (96) to increase the discharge resistance of the refrigerant.

According to the second aspect of the invention, the pressure loss means (CV-1) provided in the discharge pipe (25-D) discharges as the flow rate of the fluid discharged from the compressor (COMP-1) increases. The pressure loss inside the discharge pipe (25-D) is changed by increasing the flow passage area of the pipe (25-D). In other words, when the fluid discharge amount is small, the flow passage area is small, the rate of increase in pressure loss is high, and sufficient lubricating oil discharge amount from the oil discharge pipe (76) can be secured, while when the fluid discharge amount is large. Since the flow passage area is large and the rate of increase in pressure loss is low, it is possible to prevent the amount of lubricating oil discharged from the oil discharge pipe (76) from unnecessarily increasing.

In the invention described in claim 3, the configuration for obtaining the operation according to the invention described in claim 2 can be concretely obtained, and the practicality is improved.

[0016]

Embodiments of the present invention will now be described in detail with reference to the drawings. In addition, in this example, a case where the lubricating oil discharge structure for a compressor according to the present invention is applied to an indoor / outdoor multi-type air conditioner having a plurality of indoor units and outdoor units respectively will be described.

-Overall Structure-As shown in FIGS. 1 to 3, an air conditioner (10) as a refrigerating apparatus in the present embodiment has three outdoor units (2
A, 2B, 2C) and three indoor units (3A, 3B, 3C) are connected in parallel to the main liquid line (4L) and the main gas line (4G), respectively.

Each outdoor unit (2A, 2B, 2C) includes a compression mechanism (21), a four-way switching valve (22), and an outdoor fan (23-F).
The outdoor heat exchanger (23), which is a heat source side heat exchanger, and the outdoor electric expansion valve (24), which is a heat source side expansion mechanism.
And a heat source unit. At the gas-side end of the outdoor heat exchanger (23), a refrigerant pipe (2
5), but at the other end, which is the liquid side, the branch liquid line (5L-A, 5L-
B, 5L-C) are connected respectively.

The gas-side refrigerant pipe (25) is switchably connected to the discharge side and the suction side of the compression mechanism (21) by a four-way switching valve (22), while the branch liquid line (5L-A). ， 5L-
B, 5L-C) is provided with the outdoor electric expansion valve (24) and is connected to the outdoor heat exchanger (23) and the main liquid line (4L). And, each of the above branch liquid lines (5L-A, 5L-B,
5L-C) and the main liquid line (4L) are connected to each other by a receiver (11), and the receiver (11) connects the branched liquid lines (5L-A, 5L-B, 5L-C) to each other. Main liquid line (4L)
And are connected.

A branch gas line (5G-A, 5G-B, 5G-C) is connected to the compression mechanism (21) via a refrigerant pipe (25) and a four-way switching valve (22), and the branch Gas line (5G-A, 5G
-B, 5G-C) uses a four-way switching valve (22) to compress the compression mechanism (2
It is switchably connected to the suction side and the discharge side of 1) and is connected to the main gas line (4G). An accumulator (26) is provided in the refrigerant pipe (25) between the suction side of the compression mechanism (21) and the four-way switching valve (22).

Of the three outdoor units (2A, 2B, 2C), the first outdoor unit (2A) is the master unit, and the second outdoor unit (2B) and the third outdoor unit (2C) are the slave units. The first outdoor unit (2A) is replaced by the second outdoor unit (2A).
B) and the third outdoor unit (2C) are configured to be driven in advance, and the first outdoor unit (2A), the second outdoor unit (2B), and the third outdoor unit (2C) are mainly compression mechanisms ( The composition of 21) is different.

That is, the compression mechanism (21) of the first outdoor unit (2A) is connected to the variable capacity upstream compressor (COMP-1) which is inverter-controlled and capacity-controlled in multiple stages, and is operated and stopped. It is configured as a so-called twin type in which a constant capacity type downstream compressor (COMP-2) which is controlled to two types is connected in parallel. On the other hand, the compression mechanism (21) of the second outdoor unit (2B) and the third outdoor unit (2C) is the upstream compressor (CO
MP-1) and the downstream compressor (COMP-2) are both composed of a constant-capacity compressor controlled to two types of operation and stop,
The upstream side compressor (COMP-1) and the downstream side compressor (COMP-2) are connected in parallel to form a so-called twin type. Further, in any of the outdoor units (2A, 2B, 2C), the upstream compressor (COMP-1) is configured to drive prior to the downstream compressor (COMP-2).

On the other hand, each indoor unit (3A, 3B, 3C) is
An indoor heat exchanger (31), which is a usage-side heat exchanger in which an indoor fan (31-F) is arranged in close proximity, and an indoor electric expansion valve (32), which is a usage-side expansion mechanism, constitute a usage unit. ing. The indoor heat exchanger (31) is connected to the indoor liquid pipe (3
L) and the main liquid line (4) via the indoor gas pipe (3G)
L) and the main gas line (4G), and an indoor electric expansion valve (32) is provided in the indoor liquid pipe (3L).

-Structure of Piping Unit- The air conditioner (10) is provided with a piping unit (12) which is a connection circuit section, and the piping unit (12).
Is the branch liquid line (5L) of each outdoor unit (2A, 2B, 2C).
-A, 5L-B, 5L-C) and branch gas lines (5G-A, 5G-B, 5G)
-C) and main liquid line (4L) and main gas line (4L)
G) is connected to.

Specifically, the branch liquid lines (5L-A, 5L-B, 5L
-C) is a branch liquid pipe (5LAa, 5LBa, 5LCa) extending outside from each outdoor unit (2A, 2B, 2C) and the branch liquid pipe (5LA).
a, 5LBa, 5LCa) branch liquid passage (5LAb, 5)
LBb, 5LCb).

The above branch gas lines (5G-A, 5G-B, 5G-C)
Is a branch gas pipe (5GAa, 5GBa, 5GCa) extending from the outdoor unit (2A, 2B, 2C) to the outside, and the branch gas pipe (5GAa,
Branch gas passage (5GAb, 5G) continuous to the outer end of 5GBa, 5GCa)
Bb, 5GCb).

The main liquid line (4L) is connected to the indoor liquid pipe (3L) of the indoor unit (3A, 3B, 3C), and the main liquid pipe (4L-a). ) And the branch liquid passages (5LAb, 5LBb, 5LCb) of each of the outdoor units (2A, 2B, 2C) are connected to one end of the main fluid passage (4L-b) and communicate with each other via the receiver (11). Has been done.

The main gas line (4G) is connected to the indoor gas pipe (3G) of the indoor unit (3A, 3B, 3C), and the main gas pipe (4G-a). ) Is connected to one end of each of the outdoor units (2A, 2B, 2C) and the branch gas passages (5GAb, 5GBb, 5GCb) are connected to the main gas passage (4G-b).

The pipe unit (12) is a branch liquid line (5L-A, 5L) on the side of each outdoor unit (2A, 2B, 2C).
-B, 5L-C) branch liquid passage (5LAb, 5LBb, 5LCb) and branch gas line (5G-A, 5G-B, 5G-C) branch gas passage (5GA)
b, 5GBb, 5GCb), main liquid passage (4L-b) of main liquid line (4L) and main gas passage (4G-b) of main gas line (4G), and receiver (11) are integrally formed Has been unitized.

Further, the piping unit (12) has a first
The gas on-off valve (VR-1) and the second gas on-off valve (VR-2) are integrated into a unit. The first gas on-off valve (VR-1)
Is the branch gas passage (5GBb) on the second outdoor unit (2B) side
The second gas opening / closing valve (VR-2) is provided in the branch gas passage (5GCb) on the side of the third outdoor unit (2C) while the opening / closing mechanism is provided to open and close the branch gas passage (5GBb). Thus, an opening / closing mechanism for opening / closing the branch gas passage (5GCb) is configured.

The first gas on-off valve (VR-1) and the second gas on-off valve (VR-2) are external pressure equalizing type reversible valves and connected to the pilot circuit (50). The pilot circuit (50) has two check valves (CV, CV), a branch gas passage (5GAb) on the first outdoor unit (2A) side, and a first outdoor unit (2A) side described later. The first oil leveling auxiliary passage (77-
A) is provided with a high pressure circuit (51) that is connected to (A) and guides high pressure refrigerant, and has two check valves (CV, CV), and
A branch gas passage (5GAb) on the outdoor unit (2A) side and a first pressure equalizing auxiliary passage (77 on the first outdoor unit (2A) side, which will be described later.
-A) Low voltage circuit (52) connected to and maintaining a low voltage state
It has and.

The pilot circuit (50) includes a high pressure circuit (51) and a low pressure circuit (52) by means of a switching valve (50-S).
And the first gas on-off valve (VR-1) and the second gas on-off valve (VR-
2) is switched and connected to control the first gas on-off valve (VR-1) to be fully closed when the second outdoor unit (2B) is stopped during heating operation, and the third outdoor unit during heating operation. The second gas on-off valve (VR-2) is controlled to be fully closed when the unit (2C) is stopped.

The second outdoor unit (2B) and the third outdoor unit
The outdoor electric expansion valve (24, 24) of the outdoor unit (2C) is not provided in the piping unit (12), but the first gas on-off valve (VR-1) and the second gas on-off valve (VR-2) are provided. ) Corresponding to each of the branch liquid lines (5L-A, 5L-B, 5L-C) is also used as an opening and closing mechanism, the second outdoor unit (2B) during cooling and heating operation and 3rd outdoor unit (2
It is configured to be fully closed when C) is stopped.

-Structure of Pressure Equalizing Line- A pressure equalizing line (60) is connected between the outdoor units (2A, 2B, 2C), and the pressure equalizing line (60) connects the outdoor units ( 2A, 2B, 2C) outdoor heat exchanger (23)
Is connected to the gas side refrigerant pipes (25, 25, 25) and is configured to allow bidirectional refrigerant flow between the outdoor units (2A, 2B, 2C).

The pressure equalizing line (60) is a pressure equalizing pipe (61-A, 61-B, extending outside the outdoor units (2A, 2B, 2C)).
A pressure equalizing passage (62) is continuously formed at the outer end of (61-C). The pressure equalizing passage (62) is connected to the piping unit (1
2), the first pressure equalizing valve (SVB1) and the second pressure equalizing valve (SVB1) are provided in the branch pipe portion branched from the first outdoor unit (2A) side to the second outdoor unit (2B) side and the third outdoor unit (2C) side. A pressure equalizing valve (SVB2) is provided.

The first pressure equalizing valve (SVB1) is fully closed when the cooling operation of the second outdoor unit (2B) is stopped to prevent the refrigerant from flowing to the second outdoor unit (2B), and the second pressure equalizing valve (SVB1) is closed. (SVB
2) is configured to be fully closed when the cooling operation of the third outdoor unit (2C) is stopped to prevent the refrigerant from flowing to the third outdoor unit (2C).

-Structure of Auxiliary Refrigerant Circuit- Each of the outdoor units (2A, 2B, 2C) has a compression mechanism (2
1) is provided with an oil return mechanism (70) for returning lubricating oil, and the oil return mechanism (70) includes an oil separator (71), a first oil return pipe (72), and a second oil return pipe (70). 73) and oil level bypass pipe (7
4) and are provided.

On the other hand, the suction pipe (25-S) of the downstream compressor (COMP-2) which is a part of the refrigerant pipe (25) is the suction pipe (25-S of the upstream compressor (COMP-1). The pressure loss is set larger than that of S), and the oil equalizing pipe (7) is placed between both compressors (COMP-1, COMP-2).
5) is connected. As a result, the downstream compressor (COMP-1), which is on the low pressure side, is higher than the upstream compressor (COMP-1, which is on the high pressure side).
-Lubricant is supplied to 2).

The oil separator (71) is composed of an upstream compressor (COMP-1) and a downstream compressor (CO) which are a part of the refrigerant pipe (25).
It is arranged at the confluence of the discharge pipe (25-D, 25-D) with MP-2),
The discharge pipes (25-D, 25-D) of each compressor (COMP-1, COMP-2) are equipped with check valves (CV-1, CV-2). Furthermore, between the upper part of the upstream compressor (COMP-1) and the downstream side of the check valve (CV-1) of the discharge pipe (25-D), and the downstream compressor (COMP-
Oil discharge pipes (76, 76) are connected between the upper part of 2) and the downstream side of the check valve (CV-2) of the discharge pipe (25-D). Then, the respective oil discharge pipes (76, 76) are configured to discharge, for example, the lubricating oil accumulated in the upper portion of the compression portion of the scroll compressor to the discharge pipes (25-D, 25-D). . The check valve (CV-1) of the upstream compressor (COMP-1) is
It constitutes a pressure loss means, and adds pipeline resistance so that the lubricating oil is discharged when the refrigerant circulation amount is small. In other words, the pressure loss generated in this check valve (CV-1) causes a pressure difference between the upstream end and the downstream end of the oil discharge pipe (76), and this pressure difference causes the upstream compressor (COMP- The lubricating oil collected in the upper part of 1) is discharged to the discharge pipe (25-D) (details will be described later).

The structure of the check valve (CV-1) and its peripheral portion will be described below. Figure 4 shows the upstream compressor (COMP-1)
In the figure, (95) is a compressor casing, and (96) is a compressor having a pair of scrolls, which is sucked into the casing (95) from a suction pipe (not shown). Compressed refrigerant in the compression section (96) and discharge pipe (25-D)
It is designed to be discharged (see the arrow in FIG. 4). Further, the opening of the discharge pipe (25-D) in the casing (95) is opened upward, so that the lubricating oil accumulated on the upper side of the compression section (96) is difficult to be introduced. The check valve (CV-1) is the compressor (COMP-1) in the discharge pipe (25-D).
It is located between the discharge part of and the connection part of the oil discharge pipe (76). On the other hand, the oil drain pipe (76) has a casing at one end.
While being inserted into (95) and being close to the upper surface of the compression section (96), the other end is connected to the discharge pipe (25-D). And the discharge pipe (25-D) generated by the check valve (CV-1)
Due to the pressure loss inside, a pressure difference is generated at both ends of the oil discharge pipe (76), whereby the lubricating oil accumulated above the compression part (96) is discharged.

The internal structure of the check valve (CV-1) will be described below. As shown in Figure 5, this check valve (CV-1)
A valve body (92) is mounted inside a bottomed cylindrical valve casing (91). Specifically, the valve casing (91)
The side facing the discharge side of the upstream side compressor (COMP-1) is opened, and a small diameter portion (91a) located on this opening side and having a small inner diameter is continuous with the small diameter portion (91a), It has a large diameter part (91b) whose inner diameter is slightly larger than the small diameter part (91a), and the outer peripheral surface of the small diameter part (91a) is caulked to the inner surface of the discharge pipe (25-D). It is supported by the discharge pipe (25-D). In addition, one end of the valve casing (91) on the closed side is a spring contact seat (91c). Furthermore, a gap is formed between the outer peripheral surface of the large diameter portion (91b) and the inner surface of the discharge pipe (25-D), and at the position near the small diameter portion (91a) of the large diameter portion (91b). Through holes (91d, 91d) penetrating in the radial direction are formed at a plurality of positions in the circumferential direction.

On the other hand, the valve body (92) is a bottomed cylindrical member whose outer diameter is substantially equal to the inner diameter of the large diameter portion (91b), and inside the large diameter portion (91b). Can be slid and moved, and its tip (left end in FIG. 5)
A tapered surface (92a) is formed on the lower surface so that it can come into contact with a step formed at the connecting portion between the small diameter portion (91a) and the large diameter portion (91b). A coil spring (93) as an urging member is contracted between the rear end surface of the valve body (92) and the spring contact seat (91c).
The tapered surface (92a) of the tip end of the valve contacts the stepped portion, and in this contact state, the internal space of the valve casing (91) is closed, and the side surface of the valve body (92) causes the through hole (91).
d, 91d) is also blocked. And the upstream compressor (COMP
-1) drives and the inside of the discharge pipe (25-D) becomes high pressure,
Due to this high pressure (see the arrow in FIG. 5), the valve body (92) retracts while compressing the coil spring (93), and the large diameter portion (91b)
The through holes (91d, 91d) formed in the
The refrigerant discharged from (COMP-1) passes through the check valve (CV-1) and is circulated to the four-way switching valve (22) side. The above is the structure of the check valve (CV-1).

On the other hand, the first oil return pipe (72) is provided with a capillary tube (CP) and serves as an oil separator (71) and a suction pipe (25-S) of the first compressor (COMP-1). The lubricating oil connected to the oil separator (71) is always returned to the first compressor (COMP-1). The second oil return pipe (7
3) is equipped with an oil return valve (SVP2) and is connected to the oil separator (71) and the suction pipe (25-S) of the second compressor (COMP-2), and the oil return valve (SVP2) is The lubricating oil that is opened every predetermined time and is collected in the oil separator (71) is returned to the suction side of the compression mechanism (21).

The oil equalizing bypass pipe (74) is provided with an oil equalizing valve (SV
O1) and one end of the second oil return pipe (73) is an oil return valve (SV
The other end is connected to the pressure equalizing pipes (61-A, 61-B, 61-C) of the pressure equalizing line (60) upstream of P2). Then, in order to perform an oil leveling operation together with the oil leveling bypass pipe (74), the pressure leveling passage (62) of the pressure leveling line (60) is provided with
1st pressure equalization auxiliary passage (77-A) and 2nd oil equalization auxiliary passage (77-B)
And the third pressure equalization auxiliary passage (77-C) are connected, and the respective pressure equalization auxiliary passages (77-A, 77-B, 77-C) are incorporated in the piping unit (12).

The first pressure equalizing auxiliary passage (77-A) has one end on the first outdoor unit (2A) side of the pressure equalizing passage (62) and the other end on the second outdoor unit (2B) and the third outdoor unit. It is connected to the merging part of the branch gas passage (5GBb, 5GCb) of the unit (2C),
It is equipped with an oil leveling auxiliary valve (SVY1) and a check valve (CV).

The second pressure equalizing auxiliary passage (77-B) has one end on the second outdoor unit (2B) side of the pressure equalizing passage (62) and the other end on the branch gas passage of the first outdoor unit (2A). It is connected to (5GAb) and has a second oil leveling auxiliary valve (SVY2) and a check valve (CV).

The third pressure equalizing auxiliary passage (77-C) has one end on the third outdoor unit (2C) side of the pressure equalizing passage (62) and the other end on the branch gas passage of the first outdoor unit (2A). It is connected to (5GAb) and has a third oil leveling auxiliary valve (SVY3) and a check valve (CV).

The oil equalizing valve (SVO1, SVO1, SVO1)
And the first to third oil leveling auxiliary valves (SVY1, SVY2, SVY3) are 2
When performing the oil equalization operation (2 to 3 minutes) once every ~ 3 hours,
Alternatively, it is configured to be opened and closed when the above-described oil-equalizing operation is performed, such as after the end of the oil return operation or after the defrost operation during the heating operation.

The space between the branch gas passage (5GBb) of the second outdoor unit (2B) and the second pressure equalizing auxiliary passage (77-B), and the branch gas passage (5GCb) of the third outdoor unit (2C). ) And the third pressure equalizing auxiliary passage (77-C) have a capillary tube (CP), and the first gas on-off valve (VR-1) is provided during heating operation.
Also, auxiliary refrigerant passages (12-s, 12-s) for releasing refrigerant leaking from the second gas on-off valve (VR-2) are connected.

In addition, each of the outdoor units (2A, 2B, 2C)
A liquid injection pipe (2j) is connected to the branch liquid pipes (5LAa, 5LBa, 5LCa) of the liquid injection pipe (2j), and the liquid injection pipe (2j) is branched into two, and the injection valves (SVT1, SVT2) and the capillary are connected. Tube (CP,
CP) to the upstream compressor (COMP-1) and the downstream compressor (COMP-2). The above liquid injection valves (SVT1, SVT2) are used for each compressor (COMP-1, COMP
-2) It is configured to open when the discharge gas refrigerant temperature rises excessively to lower the discharge gas refrigerant temperature.

A hot gas bypass pipe (2h) is connected between the discharge side and the suction side of the compression mechanism (21) in each of the outdoor units (2A, 2B, 2C), and the hot gas bypass pipe (2h) is connected. Is equipped with a hot gas valve (SVP1) and is connected to the upstream side of the four-way switching valve (22) and the upstream side of the accumulator (26). The hot gas valve (SVP1) is configured to equalize the discharge side and the suction side of the compression mechanism (21) mainly at the time of starting or the like.

An auxiliary bypass pipe (2b) is connected between the suction side and the discharge side of the compression mechanism (21) in the second outdoor unit (2B) and the third outdoor unit (2C). The bypass pipe (2b) is provided with a check valve (CV) that allows the refrigerant flow only from the suction side to the discharge side of the compression mechanism (21), and the upstream side of the four-way switching valve (22) and the accumulator (26). It is connected to the upstream side. The auxiliary bypass pipe (2b) is provided with a branch gas line (5G-B, when the second outdoor unit (2B) and the third outdoor unit (2C) are stopped during the heating operation.
The refrigerant of 5G-C) is configured to bypass the compression mechanism (21) and be sucked into the first outdoor unit (2A).

Further, the receiver (11) and the pilot circuit (50) low-voltage circuit (52) in the piping unit (12).
A gas vent passage (12-g) is connected between and. The gas vent passage (12-g) is equipped with a gas vent valve (SVTG) and is incorporated in the piping unit (12), and the gas vent valve (SVTG)
Is configured to open for high pressure protection during cooling operation and low pressure protection during heating operation.

-Structure of Sensors- Various sensors are provided in each of the outdoor units (2A, 2B, 2C) and each of the indoor units (3A, 3B, 3C).
In each of the outdoor units (2A, 2B, 2C), an outdoor air temperature sensor (Th-1) for detecting the outdoor air temperature is provided near the outdoor heat exchanger (23), and the liquid refrigerant of the outdoor heat exchanger (23). The outdoor liquid temperature sensor (Th-2) that detects the temperature is connected to the branch pipe of the branch liquid line (5L-A, 5L-B, 5L-C). Temperature sensors (Th31, Th32) are each compressor (COMP-1, COMP-2)
A suction gas temperature sensor (Th-4) for detecting the temperature of the suction gas refrigerant of the compression mechanism (21) is attached to the discharge mechanism (21) of the compression mechanism (21).
Compressor (COMP-1, COMP-2) in the suction side refrigerant pipe (25)
Oil temperature sensor (Th51, Th
52) is the lower part of each compressor (COMP-1, COMP-2), and the outdoor gas temperature sensor (Th-6) for detecting the temperature of the gas refrigerant of the outdoor heat exchanger (23) is located on the gas side refrigerant pipe (25). ) Are provided respectively.

Further, in the first outdoor unit (2A), a high pressure sensor (SP-H) for detecting the discharge refrigerant pressure of the compression mechanism (21) is connected to the discharge side refrigerant pipe (25) of the compression mechanism (21). ,
A low pressure sensor (SP-L) for detecting the suction refrigerant pressure of the compression mechanism (21) is provided in each of the suction side refrigerant pipes (25) of the compression mechanism (21), and each compressor (COMP-1, COMP-
The high pressure protective switch (H-PS, H-PS) that operates when the discharge refrigerant pressure in 2) reaches a specified high pressure is used for each compressor (COMP-1, COMP-2).
It is installed on the discharge pipe (25-D, 25-D) of.

Further, since the second outdoor unit (2B) and the third outdoor unit (2C) are provided with the pressure equalizing line (60), the high pressure sensor (SP) like the first outdoor unit (2A) is provided. -H) and low pressure sensor (SP-L) are not provided, and a high pressure protective switch (H-PS) that operates when the discharge refrigerant pressure of each compressor (COMP-1, COMP-2) reaches a specified high pressure. , H-PS)
Is the discharge pipe (25-D, 25-D) of each compressor (COMP-1, COMP-2)
In addition, the high pressure control switch (HPSC) that operates when the discharge refrigerant pressure of the compression mechanism (21) becomes a predetermined high pressure lower than the high pressure protection switch (H-PS, H-PS) discharges the compression mechanism (21). A low-pressure protection switch (L-PS) that operates when the suction refrigerant pressure of the compression mechanism (21) becomes a predetermined low pressure is provided in the side refrigerant piping (25) in the suction side refrigerant piping (25) of the compression mechanism (21). Has been.

On the other hand, in each indoor unit (3A, 3B, 3C), a room temperature sensor (Th-7) for detecting the indoor air temperature is provided in the vicinity of the indoor fan (31-F) and the indoor heat exchanger (31). Indoor liquid temperature sensor (Th-8) to detect the liquid refrigerant temperature of the indoor liquid pipe (3L),
An indoor gas temperature sensor (Th-9) for detecting the temperature of the gas refrigerant in the indoor heat exchanger (31) is provided in each of the indoor gas pipes (3G).

-Control Configuration- The air conditioner (10) is provided with a controller (80), and the controller (80) includes the sensors (Th-1 to SP).
-L) and switch (H-PS to L-PS) detection signals are input,
The opening degree of each electric expansion valve (24-32), the capacity of the compression mechanism (21), etc. are controlled based on the detection signal of each sensor (Th-1 to SP-L).

-Operation of Air Conditioning Operation- Next, the control operation of the air conditioning operation in the air conditioner (10) will be described.

First, during the cooling operation, the four-way switching valve (22) is switched to the solid line in FIGS. 2 and 3, and the high pressure discharged from the compression mechanism (21) of each outdoor unit (2A, 2B, 2C). The gas refrigerant is condensed in the outdoor heat exchanger (23) to become a liquid refrigerant,
This liquid refrigerant flows into the main liquid passage (4L) of the piping unit (12).
-Join at b). After that, the liquid refrigerant is decompressed by the indoor electric expansion valve (32) and then evaporated in the indoor heat exchanger (31) to become a low-pressure gas refrigerant. This gas refrigerant is branched into each branch gas in the piping unit (12). The flow is divided into the passages (5GAb, 5GBb, 5GCb), returned to the compression mechanism (21) of each outdoor unit (2A, 2B, 2C), and this circulation operation is repeated.

On the other hand, during the heating operation, the four-way switching valve (22) switches to the broken lines in FIGS. 2 and 3, and discharges from the compression mechanism (21) of each outdoor unit (2A, 2B, 2C). The high-pressure gas refrigerant flows into the piping unit (12), merges in the main gas passage (4G-b) of the piping unit (12), and then flows into the indoor units (3A, 3B, 3C). Then, this gas refrigerant is condensed in the indoor heat exchanger (31) to become a liquid refrigerant, and this liquid refrigerant is the main liquid passage (4L-
It is branched from b) to the branch liquid passages (5LAb, 5LBb, 5LCb) on the side of each outdoor unit (2A, 2B, 2C). After that, this liquid refrigerant is decompressed by the outdoor electric expansion valve (24), then evaporated in the outdoor heat exchanger (23) to become a low-pressure gas refrigerant, and the compression mechanism of each outdoor unit (2A, 2B, 2C) ( Returning to 21), this circulation operation is repeated.

During the cooling operation and the heating operation,
The controller (80) is an electric expansion valve for each room (32, 32, 32)
And the opening degree of each outdoor electric expansion valve (24, 24, 24) is controlled, and each outdoor unit (2A, 2B,
The capacity of the compression mechanism (21) in 2C) is controlled. Specifically, the controller (80) includes the first outdoor unit (2
The capacity of the upstream compressor (COMP-1) in A) is controlled almost linearly in response to the load by inverter control.
Operate and stop the downstream compressor (COMP-2) of the outdoor unit (2A) and the compressors (COMP-1, COMP-2) of the second outdoor unit (2B) and the third outdoor unit (2C) is doing.
When the load on the indoor units (3A, 3B, 3C) decreases, the operation of the third outdoor unit (2C) and the second outdoor unit (2B) is stopped in this order, and conversely, the indoor units (3A, 3A, 3C) are stopped.
3B, 3C) load increases, the second outdoor unit (2B)
Then, the operation will be started in the order of the third outdoor unit (2C).

Further, in each of the outdoor units (2A, 2B, 2C) operating in both the cooling operation and the heating operation, the first pressure equalizing valve (SVB1) and the second pressure equalizing valve (SVB1)
2) is opened, the high-pressure gas refrigerant flows substantially evenly through the outdoor heat exchangers (23, 23, 23) during the cooling operation, and the low-pressure gas refrigerant flows through the outdoor heat exchangers (23, 23, 23) during the heating operation. 23, 23) will flow almost evenly.

That is, during the cooling operation, for example, when the operating capacity of the third outdoor unit (2C) becomes large with respect to the cooling load, a part of the refrigerant discharged from the compression mechanism (21) is equalized by the pressure equalizing line (60). Through the outdoor heat exchangers (23, 2) in the first outdoor unit (2A) and the second outdoor unit (2B)
It will flow to 3). Conversely, during heating operation,
For example, when the operating capacity of the third outdoor unit (2C) becomes large with respect to the heating load, a part of the refrigerant sucked into the compression mechanism (21) of the first outdoor unit (2A) and the second outdoor unit (2B). Will be sucked into the compression mechanism (21) of the third outdoor unit (2C) through the pressure equalizing line (60).

-Opening / closing operations of various valves-When the cooling operation of the third outdoor unit (2C) is stopped,
The outdoor electric expansion valve (24) and the second pressure equalizing valve (SVB2) are closed to prevent the liquid refrigerant from accumulating in the stopped third outdoor unit (2C), and similarly, for the second outdoor unit (2B). When the cooling operation is also stopped, the outdoor electric expansion valve (24) and the first pressure equalizing valve (SVB1) are closed, and the second outdoor unit (2
The liquid refrigerant is prevented from accumulating in B), and the shortage of the refrigerant amount between the first outdoor unit (2A) and the indoor units (3A, 3B, 3C) is prevented. Since the branch gas lines (5G-A, 5G-B, 5G-C) are in a low pressure state when the cooling operation of the third outdoor unit (2C) and the second outdoor unit (2B) is stopped, The on-off valve (VR-1) and the second gas on-off valve (VR-2) are open.

On the other hand, when the heating operation of the third outdoor unit (2C) is stopped, the outdoor electric expansion valve (24) and the second gas on-off valve (VR-2) are closed to stop the third outdoor unit (2C). )
When the liquid refrigerant does not accumulate in the room and the heating operation of the second outdoor unit (2B) is also stopped, the outdoor electric expansion valve (24) and the first gas on-off valve (VR-1) are closed and stopped. Prevents liquid refrigerant from accumulating in the second outdoor unit (2B) inside, and prevents shortage of the amount of refrigerant between the first outdoor unit (2A) etc. and each indoor unit (3A, 3B, 3C) To do.
The third outdoor unit (2C) and the second outdoor unit (2C
When the heating operation of B) is stopped, the pressure equalizing line (60) communicates with the low pressure side of the first outdoor unit (2A), so the second pressure equalizing valve (SVB2) and the first pressure equalizing valve (SVB1) are open. There is.

Further, immediately after the heating operation of the third outdoor unit (2C) and the second outdoor unit (2B) is stopped, for example, when the third outdoor unit (2C) is stopped, the third outdoor unit (2C) is stopped. The outdoor electric expansion valve (24) and the second gas opening / closing valve (VR-2) are opened for a predetermined time, and
Leave open for 2 minutes. As a result, the high-pressure gas refrigerant from the first outdoor unit (2A), etc. passes through the branch gas line (5G-C) and the auxiliary bypass pipe (2b) of the third outdoor unit (2C) to the branch liquid line (5L-C). ), The liquid refrigerant in the stopped third outdoor unit (2C) flows into the main liquid line (4C).
It is released to L) to prevent a shortage of refrigerant.

Further, during the cooling operation and the heating operation, each oil equalizing valve (SVO1, SVO1, SVO1) and each oil equalizing auxiliary valve (SV)
Y1, SVY2, SVY3) are closed together, while the oil separator (7
The lubricating oil accumulated in 1) always returns from the first oil return pipe (72) to the compression mechanism (21), and at the same time, the oil return valve (SVP)
2) is opened to return the lubricating oil accumulated in the oil separator (71) from the second oil return pipe (73) to the compression mechanism (21).

Further, during both the cooling operation and the heating operation, the oil equalizing valves (SVO1, SVO1, SVO1) and the oil equalizing auxiliary valves (SVY1, SVY2, SVY3) are controlled to be opened and closed as appropriate. The operation is performed so that the amount of lubricating oil in the compression mechanism (21) of each outdoor unit (2A, 2B, 2C) becomes equal.

Next, the characteristic operation of this example will be described. This is an operation of discharging the lubricating oil accumulated in the upper portion of the compression section (96) of the upstream compressor (COMP-1) to the discharge pipe (25-D). That is, the valve body (92) of the check valve (CV-1) retracts against the biasing force of the coil spring (93) due to the pressure of the refrigerant discharged from the upstream compressor (COMP-1). Then, at this time, the retracted position of the valve body (92) is determined by the balance between the pressure of the discharged refrigerant and the biasing force of the coil spring (93), and the opening degree of the through holes (91d, 91d) is thereby opened to a predetermined level. It is set to every. That is, when the pressure of the discharged refrigerant is low, the through hole (91
The opening of d, 91d) is small, and the opening of the through hole (91d, 91d) increases as the pressure increases. FIG. 6 shows the relationship between the refrigerant mass flow rate from the upstream compressor (COMP-1) and the pressure loss in the check valve (CV-1) during such operation. As can be seen from FIG. 6, until the check valve (CV-1) is fully opened (A region in FIG. 6), the increase rate of the pressure loss with respect to the increase of the refrigerant mass flow rate is gradually small, In other words, the increase rate of pressure loss is large in the region where the opening of the check valve (CV-1) is small, whereas the increase rate of pressure loss is large in the region where the opening of the check valve (CV-1) is large. It is getting smaller. Therefore, in the operating region where the capacity of the upstream compressor (COMP-1) is small, the amount of lubricating oil discharged from the oil discharge pipe (76) can be secured sufficiently, while the capacity of the upstream compressor (COMP-1) is In a large operation range, it is possible to prevent the amount of lubricating oil discharged from the oil discharge pipe (76) from increasing more than necessary. Therefore, the amount of lubricating oil discharged from the oil discharge pipe (76) can be appropriately set over a wide range of the operation range of the upstream compressor (COMP-1), and a large amount of lubricating oil can be provided above the compression unit. Occurrence of a situation in which the oil is accumulated or the amount of lubricating oil discharged from the oil discharge pipe (76) becomes too large is avoided.

As described above, according to the configuration of this example, the compression unit (9
Since the lubricating oil accumulated on the upper side of (6) can be satisfactorily discharged to the oil separator (71), the lubricating oil accumulated on the upper side of the compression section (96) becomes the discharge resistance of the refrigerant and reduces the compressor performance. It is possible to avoid a decrease and to improve the capacity of the compressor. Also, the compression unit (96)
It is possible to set the inner diameter of the oil recovery passage to be small even if the oil recovery passage for communicating the upper space and the lower space of the casing (95) is not required or the oil recovery passage (98) is provided as shown in FIG. Therefore, it is possible to avoid a large amount of high-pressure refrigerant bypassing to the low-pressure side, which also improves the performance of the compressor. Even if the lubricating oil accumulates above the compression section of one compressor (COMP-1), this lubricating oil is discharged to the discharge pipe (25-D), so the other compressor (COMP- It is possible to avoid the situation in which the storage amount of the lubricating oil is insufficient in 2), and it is possible to ensure good lubricity of the compressor (COMP-2).

In this example, the opening degree of the check valve (CV-1) is set according to the refrigerant circulation amount by applying an urging force from the coil spring (93) to the valve body (92). However, a reed valve made of a plate material may be provided, and the opening degree of the reed valve may be changed according to the refrigerant circulation amount.

-Modification-Next, the lubricating oil accumulated on the upper side of the compression portion (96) is supplied to the oil discharge pipe (76).
Two modified examples for generating a pressure loss in the discharge pipe (25-D) for discharging by the above will be described with reference to FIG. First, as a first modification, as shown in the figure, the discharge pipe (25-D) to the oil discharge pipe from the discharge part of the compressor (COMP-1)
The length dimension up to the connection part of (76) is set longer than the length dimension of the oil discharge pipe (76). That is, the discharge pipe (25-D) is bent so that a part of the discharge pipe (25-D) is brought close to the connection position of the oil discharge pipe (76) to the casing. 25-D) is connected at the downstream end.

According to this structure, the pressure loss in the discharge pipe (25-D) is larger than the pressure loss in the oil discharge pipe (76), and the upstream of the oil discharge pipe (76) is large. Due to the pressure difference between the end portion and the downstream end portion, the lubricating oil accumulated above the compression portion (96) can be discharged through the oil discharge pipe (76).

As a second modification, the compressor (COMP-1) in the discharge pipe (25-D) is shown by the phantom line in FIG.
In the part between the discharge part of and the connection part of the oil discharge pipe (76),
The small-diameter portion (97) formed to have a small diameter is partially provided. This also increases the pressure loss in the discharge pipe (25-D) with respect to the pressure loss in the oil discharge pipe (76), so that the upstream end and the downstream end of the oil discharge pipe (76) are Compressed part due to pressure difference
The lubricating oil accumulated on the upper side of (96) can be discharged through the oil discharge pipe (76).

According to the two modified examples described above, the discharge pipe
(25-D) The pressure loss can be generated by itself, and the lubricating oil accumulated on the upper side of the compression section (96) is discharged by the oil discharge pipe (76) with a simple structure without increasing the number of parts. be able to.

The present invention is not limited to the twin type compression mechanism (21) as in this example, but can be applied to an outdoor unit equipped with one compressor, and a plurality of outdoor units. The present invention is not limited to those equipped with the units (2A, 2B, 2C), and can be applied to an air conditioner equipped with one outdoor unit.

[0078]

As described above, according to the present invention, the following effects are exhibited. According to the invention described in claim 1, an oil discharge pipe for discharging the lubricating oil accumulated in the upper space of the compression unit to the discharge pipe is provided between the upper space of the compression unit and the intermediate portion of the discharge pipe. Since the discharge pipe causes pressure loss in the discharge fluid from the discharge part of the compressor to the connection part of the oil discharge pipe, the lubricating oil accumulated on the upper side of the compression part is satisfactorily discharged to the discharge pipe. It is possible to discharge the lubricating oil, and it is possible to prevent the lubricating oil from becoming the discharge resistance of the refrigerant, and it is possible to improve the capacity of the compressor. Further, unlike the conventional case, the oil recovery passage for communicating the upper space of the compression portion and the lower space of the casing is not necessary, and even when the oil recovery passage is provided, the inner diameter of the lubricating oil can be set small and the lubricating oil Since it can be sufficiently discharged, it is possible to avoid bypassing a large amount of high-pressure refrigerant to the low-pressure side, thereby improving the performance of the compressor.

According to the second aspect of the invention, the discharge pipe includes:
Since the pressure loss means for changing the pressure loss inside the discharge pipe is increased by increasing the flow passage area of the discharge pipe as the flow rate of the fluid discharged from the compressor increases, the flow passage is reduced when the fluid discharge amount is small. While the area is small and the increase rate of pressure loss is high, the amount of lubricating oil discharged from the oil discharge pipe can be secured sufficiently, while when the fluid discharge amount is large, the flow passage area is large and the increase rate of pressure loss is low. It is possible to prevent the amount of lubricating oil discharged from the oil discharge pipe from increasing more than necessary. Therefore, it is possible to properly set the amount of lubricating oil discharged from the oil discharge pipe over a wide range of the operation area of the compressor, and a large amount of lubricating oil is accumulated on the upper side of the compression section, or the lubricating oil from the oil discharge pipe is lubricated. It is possible to avoid the situation where the oil discharge amount becomes too large.

According to the third aspect of the present invention, the pressure loss means is a check valve having a valve body which is opened by the pressure of the fluid discharged from the compressor, and the valve body is provided with a pressure resistance against the fluid discharged. Since the urging force is applied by the urging member, the configuration for obtaining the effect according to the invention described in claim 2 can be specifically obtained, and the practicality can be improved.

[Brief description of drawings]

FIG. 1 is a system diagram of an air conditioner according to an embodiment.

FIG. 2 is a piping system diagram of a first outdoor unit.

FIG. 3 is a piping system diagram of second and third outdoor units.

FIG. 4 is a cross-sectional view showing a configuration of a compressor upper portion.

FIG. 5 is a cross-sectional view showing the structure of a check valve.

FIG. 6 is a diagram showing a relationship between a refrigerant mass flow rate and a pressure loss in a discharge pipe.

[Explanation of symbols]

(25-D) Discharge pipe (76) Oil discharge pipe (93) Coil spring (biasing member) (95) Casing (96) Compressor (COMP-1) Upstream compressor (CV-1) Check valve (pressure loss means)

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Mari Sada, 1304 Kanaoka-machi, Sakai City, Osaka Prefecture Daikin Industrial Co., Ltd.Kanaoka Plant, Sakai Factory (72) Hiromune Matsuoka, 1304, Kanaoka-machi, Sakai City, Osaka Prefecture Daikin Industries, Ltd. Kanaoka Plant, Sakai Works Co., Ltd. (72) Inventor, Kiichi Masashige 1304, Kanaoka Town, Sakai City, Osaka Prefecture Daikin Kogyo Co., Ltd. Kanaoka Factory, Sakai Seisakusho Co., Ltd. (56) Reference JP-A-4-12187 (JP, A) JP-A-4-365993 (JP, A) JP-A-6-280768 (JP, A) JP-A-1 -159492 (JP, A) JP-A-63-205489 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) F04C 23/00-29/10 F04B 39/00-39/16

Claims (3)

(57) [Claims] 1. A compression unit (9) provided in a casing (95).
In the compressor (COMP-1) that compresses the fluid by (6) and discharges it to the discharge pipe (25-D), between the upper space of the compression part (96) and the middle part of the discharge pipe (25-D). The oil discharge pipe (76) for discharging the lubricating oil accumulated in the upper space of the compression section (96) to the discharge pipe (25-D) is installed in the above, and the discharge pipe (25-D) and the above The oil drain pipe (76) is
Open to the space above the compression section (96) in the ring (95), the discharge pipe (25-D) is not affected by the pressure loss in the oil discharge pipe (76).
So that the pressure loss in the discharge pipe (25-D) becomes larger.
In addition, the lubricating oil discharge of the compressor is characterized in that pressure loss is generated in the discharge fluid between the discharge part of the compressor (COMP-1) and the connection part of the oil discharge pipe (76). Construction. 2. The discharge pipe (25-D) is provided with a compressor (COM) at an upstream side of a connection portion of the oil discharge pipe (76) in a flow direction of discharge fluid.
The higher the flow rate of the fluid discharged from (P-1), the discharge pipe (25-D)
The lubricating oil for the compressor according to claim 1, further comprising a pressure loss means (CV-1) for increasing a flow passage area of the discharge pipe (25-D) to change a pressure loss inside the discharge pipe (25-D). Discharge structure. 3. The pressure loss means comprises a check valve (CV-1) having a valve body (92) that is opened by the pressure of the fluid discharged from the compressor (COMP-1). The lubricating oil discharge structure for a compressor according to claim 2, wherein a biasing force against the pressure of the discharge fluid is applied to the (92) by a biasing member (93).