JPH04365993A - Scroll compressor - Google Patents

Abstract

PURPOSE:To maintain equal amount of oil for each compressor in a freezing cycle using a plurality of compressors by sucking oil with a discharging gas so as to discharge the oil when the amount of oil in the compressor is so increased that the oil level reaches an oil discharging tube, and whereby maintaining a constant level of the amount of oil in the compressor. CONSTITUTION:A compression mechanism of a scroll compressor 1 is stored in a closed container 9. The compression mechanism is composed of a compression mechanism part and an electric motor 15. The compression mechanism part is composed of a turning scroll 11, a fixed scroll 12, a driving shaft 13, a frame 14 and of an Oldham's ring 15. The lower and inner part of the closed container 9 is an oil sump. A check valve 16 is arranged on the suction hole of the fixed scroll 12, and a suction tube 17 integrated with a cap 9c is inserted therein. A discharging tube 18 is arranged on the cap 9c, and an oil discharging tube 19 is arranged on a throttle part 18a of the discharging tube 18. The oil that reached the oil discharging tube 19 is suctioned by the throttle part 18a, and is discharged along with discharging gas.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scroll compressor used for air conditioning and refrigeration, and more particularly to a structure for maintaining a constant amount of oil in each compressor in a refrigeration cycle using a plurality of compressors.

0002

2. Description of the Related Art An example of a conventional refrigeration cycle using a plurality of compressors is shown in FIG.

The refrigeration cycle is composed of a plurality of compressors 1, oil separators 2, condensers 3, expansion valves 4, evaporators 5, accumulators 6, and oil return pipes 7.

Gas and oil discharged from the compressor 1 are separated in an oil separator 2, liquefied in a condenser, vaporized under reduced pressure in an expansion valve 4, cooled in an evaporator 5, and then transferred to an accumulator. 6, and is sucked into the compressor again.

When the oil accumulated in the oil separator exceeds a certain level, it is automatically returned to the upstream part of the accumulator through the near-oil pipe 7 by a float valve or the like, and is returned to the compressor together with the suction gas.

[0006] There are the following problems in retaining oil in a plurality of compressors using this method.

(1) Since the oil rise (the amount of oil discharged together with the discharged gas) differs depending on the compressor, the rate at which the oil in the compressor decreases differs.

(2) The amount of oil that returns to the compressor from the suction side is not equal in each compressor depending on the shape of the suction pipe, and related to (1), the rate of change in the amount of oil in each compressor is different.

(3) When a plurality of compressors are used, the discharge amount of each compressor is not necessarily the same. In other words, when using compressors with different discharge volumes, when using compressors that can vary the discharge volume such as inverter drive, twin compressors, compressors with unloaders, etc., and of course some of the multiple units must be stopped. It may be used in some cases. In all of these cases, it is extremely difficult to maintain a constant amount of oil in each compressor due to the relationships (1) and (2) described above.

[0010] If the amount of oil in the compressor is insufficient, there will be insufficient oil supply to the sliding parts, resulting in poor lubrication and burnout of the bearings.

On the other hand, if the amount of oil is too large, the expansion loss will increase and the performance will deteriorate. Furthermore, if the engine stops with a large amount of oil, or if the amount of oil increases while the engine is stopped, a large amount of oil will enter the compression mechanism, causing liquid compression, resulting in startup failure and damage to mechanical parts.

[0012] In order to maintain the oil amount in each compressor,
There is also a method of branching out the oil return pipe shown in Figure 1 and connecting it to each compressor, and returning oil to each compressor in sequence and periodically, but this requires complicated control and parts such as timers and solenoid valves. Furthermore, it is not possible to prevent excess oil.

[0013]

SUMMARY OF THE INVENTION An object of the present invention is to prevent an imbalance in the amount of oil in each scroll compressor, which occurs when a plurality of scroll compressors are used in one refrigeration cycle. The purpose is to maintain a constant amount of oil in the compressor.

[0014]

[Means for Solving the Problems] As a method of keeping the amount of oil in the compressor constant, a certain amount or more of oil is forcibly discharged from the compressor.

[0015] Since the discharged oil returns from the suction side, even if there are a plurality of compressors, the amount of oil in all the compressors can be kept approximately equal.

Specifically, each compressor is provided with an oil drain pipe, and the oil level (oil amount) inside the compressor is kept constant at the position of this oil drain pipe.

A similar effect can be obtained by making a discharge pipe protrude into the container instead of the oil drain pipe.

[0018] As a suction force for oil from the oil drain pipe, an ejector using a discharge pipe or a high-pressure side pipe of a refrigeration cycle can be used.

[0019]

[Operation] When the amount of oil in the compressor increases and the oil level reaches the oil drain pipe, the oil is sucked into the discharged gas and discharged. Since the amount of oil in each compressor can be kept at the upper limit, it is possible to prevent the amount of oil from decreasing excessively.

[0020]

Embodiment An embodiment of the present invention will be explained with reference to FIGS. 2 to 8.

FIG. 2 shows a scroll compressor showing one embodiment of the present invention.

The compressor 1 has a compression mechanism 8 housed in a closed container 9 in a horizontal arrangement. The compression mechanism 8 includes a compression mechanism section 10 and an electric motor 15.

The compression mechanism section consists of an orbiting scroll 11, a fixed scroll 12, a drive shaft 13, a frame 14, and an Oldham ring 15.

The orbiting scroll has a spiral wrap 11b on an end plate 11a, and an orbiting bearing 11c on the back surface (on the side opposite to the wrap) of the end plate.

Further, a pressure equalizing hole 11d is provided in the end plate.

The fixed scroll has a spiral wrap 12b on an end plate 12a, and a discharge hole 12 in the center of the end plate.
c, suction holes 12d are provided on the outer periphery. Further, the outer closing portion of the mirror plate has an outer wall 12e.

The drive shaft has an eccentric shaft 13a at one end. Further, a balance weight 13b is installed. An oil supply hole 13c is provided inside the shaft.

The frame 14 has an oil inlet 14c for supplying oil to the bearings 14a, 14b and the oil supply hole 13c of the drive shaft.

[0029] Orbiting scroll 11 and fixed scroll 12
are assembled with the wrap facing inward, and the outer wall of the fixed scroll is fastened to the frame. A back pressure chamber 14e is formed on the back surface of the orbiting scroll.

The eccentric shaft of the drive shaft is inserted into the swing bearing,
An Oldham ring is installed between the frame and the orbiting scroll.

The shaft is supported by a bearing in the frame, and a rotor 15a of an electric motor 15 is installed at the end of the shaft. The stator 15b of the electric motor is fastened to the legs 14d of the frame.

The compression mechanism 8 is fixed to a seat 9b provided on the body 9a of the container 9.

A check valve 16 is installed in the suction hole of the fixed scroll, and a suction pipe 17 integrated with the cap 9c is inserted. A discharge pipe 18 is installed in the other cap 9c. An oil drain pipe 19 is installed in the constricted portion 18a of the discharge pipe.

[0034] The lower part of the container is an oil sump.

When the electric motor rotates, the orbiting scroll
The Oldham ring performs a rotating motion, compressing the gas sucked in through the suction hole, and expelling it through the discharge hole. The discharged gas flows to the motor side through the gas passage 14f and is discharged from the discharge pipe.

Since the back pressure chamber communicates with the space in the middle of compression through the pressure equalization hole, an intermediate pressure higher than the suction pressure and lower than the discharge pressure is created, which presses the orbiting scroll against the fixed scroll.

[0037] Furthermore, the bearing is lubricated by the pressure difference between the pressure inside the container (discharge pressure) and the pressure inside the container (discharge pressure). Oil sucked in from the suction port is supplied to each bearing through the oil supply hole. The oil discharged from the bearing passes through the back pressure chamber and the pressure equalization hole, is discharged from the discharge hole together with the compressed gas, is separated from the gas, returns to the oil reservoir, and a portion is discharged from the discharge pipe together with the gas.

When the oil in the compressor decreases, gas is sucked in from the suction port, resulting in poor lubrication. On the other hand, if there is a lot of oil, it will be agitated by the motor's rotor and the power will increase. Furthermore, when the engine stops in this state, oil flows into the compression chamber from the discharge hole, causing liquid compression at the next startup.

In the present invention, when oil reaches the oil drain pipe, the oil is sucked by the ejector effect of the constricted portion 18a of the discharge pipe 18 and is discharged together with the discharge gas, so that the oil does not accumulate above the oil drain pipe.

The oil drain pipe can also be used as a discharge pipe as in the embodiment shown in FIG.

Furthermore, as in the embodiment shown in FIG. 4, the oil drain pipe can be taken out of the container alone and connected to a high pressure pipe externally.

These embodiments cannot be applied to a twin scroll compressor in which two compression mechanisms are housed in a container as shown in FIG. 5, or a vertical scroll compressor as shown in FIG. 6.

Although the scroll compressor of the present invention can be used in the conventional refrigeration cycle shown in FIG. 1, it is also possible to remove the oil separator as shown in FIG.

Furthermore, when a compressor is used in the embodiment shown in FIG. 4, the constriction section 20 is installed in the high-pressure side collecting pipe of the cycle as shown in FIG.
There is also a way to connect to 0. In this case, suction force can be applied even to a stopped compressor among the plurality of compressors.

[0045]

[Effects of the Invention] According to the present invention, the amount of oil in the compressor is kept constant and oil exceeding a certain level is forcibly discharged. Able to maintain quantity.

[Brief explanation of drawings]

FIG. 1 is a system diagram of a conventional refrigeration cycle that uses multiple compressors.

FIG. 2 is a sectional view showing the structure of a scroll compressor according to an embodiment of the present invention.

FIG. 3 is a partial sectional view of a scroll compressor showing another embodiment of the present invention.

FIG. 4 is a partial sectional view of a scroll compressor showing another embodiment of the present invention.

FIG. 5 is a sectional view showing another structure to which the present invention can be applied.

FIG. 6 is a sectional view showing another structure to which the present invention can be applied.

FIG. 7 is a system diagram of a refrigeration cycle having a plurality of compressors using the scroll compressor of the present invention.

FIG. 8 is a system diagram of a refrigeration cycle having a plurality of compressors using the scroll compressor of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1... Compressor, 2... Oil separator, 9... Sealed container, 18... Discharge pipe, 18a, 20... Throttle, 19... Oil drain pipe.

Claims (1)

[Claims] 1. A scroll compressor in which a scroll compression mechanism is housed in a closed container, a discharge pressure is provided in the sealed container, and a lubricating oil reservoir is provided below the sealed container, wherein the amount of oil in the sealed container is A scroll compressor characterized by being provided with means for preventing the amount from increasing beyond a certain amount.