JPH0932779A - Compression unit of refrigerating machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compression unit of a refrigerating machine, in which piping structure is simple, the number of parts can be decreased, piping vibration to be generated caused by pressure pulsation is prevented, and retrigerating capacity can be improved, by adjusting an oil injecting amount by a throttle mechanism according to the pump performance of an oil pump and a leak amount from a compression chamber of a compression element. SOLUTION: Oil in a compressor dome 12 of a compressor 1 is pumped up by an oil pump 7 and injected into a compression chamber of a compression element 13 through an injection passage 8, and gas is cooled. A throttle mechanism 82 for controlling an injection oil amount is interposed in the injection passage 8, so as to control the oil injection amount to a suitable amount. An oil separator 5 is interposed in a discharge line 32 of the compressor 1, an oil returning passage 9 for returning oil to the compressor dome 12 is connected to the bottom of the oil separator 5, so as to recover oil accumulated in the oil separator 5 into the dome 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly uses helium gas as a working fluid, and in order to prevent the temperature of the compressed gas and the internal temperature of the compression element from rising, oil is injected into the compression chamber of the compression element to supply the gas. The present invention relates to a compressor compression unit for a refrigerator.

[0002]

2. Description of the Related Art A compression unit of a refrigerator having a compressor for pumping oil in a compressor dome with an oil pump and injecting the oil into a compression chamber through an injection passage is disclosed in Japanese Patent Application Laid-Open No. 4 (1994) -54187.
It is disclosed in Japanese Patent No. 12187.

As shown in FIG. 5, this conventional compression unit is provided with a compressor D in which a compression element B and a motor C are installed in a compressor dome A, and a low pressure helium gas is compressed from a suction line E. After being introduced into the machine dome A and compressed in the compression element B, the compressed helium gas is sent to the cryogenic expander G through the discharge line F, and the low pressure expanded in the expander G is supplied. Helium gas is returned from the suction line E into the compressor dome A.

Conventionally, an oil sump H is formed in the bottom of the compressor dome A, and the oil in the oil sump H is pumped up by an oil pump J, and the oil is accumulated in the compression element B through the injection passage K1. Was injected to cool the gas in the compression element B with oil. The injection passage K1
An oil cooler L for cooling the oil is interposed in the.

Further, an oil separator M is provided in the discharge line F, and the oil separated by the oil separator M is returned to the compressor dome A through an oil return passage N. The amount of oil in the oil sump H pumped up by the oil pump J was secured, and the motor C was cooled by returning oil. The oil return passage N has one end connected to the bottom of the oil separator M, and the other end connected to the suction line E near the inlet to the compressor dome A. A diaphragm P for controlling is provided.

[0006]

However, in the conventional gas cooling by oil injection, the oil pump J is usually a positive displacement pump provided at the end of the drive shaft of the motor C. When pumping, the oil pump J is not always pumped with a constant amount of oil, but is pumped with the amount of oil varying with the rotation of the drive shaft.
There was a variation in the oil injection into the compression element B due to the oil flow, and there was a problem that the gas cooling by the oil was not performed efficiently. In addition, the pressure pulsation of the oil caused due to the fluctuation of the oil amount caused the pulsation in the compression unit. Pipe vibration was also caused by.

Therefore, as disclosed in Japanese Patent Application Laid-Open No. 4-325793, as shown in FIG. 6, there has been proposed one in which the oil mainly accumulated in the oil separator M in which the pressure fluctuation of the oil is small is injected into the compression element. . Further, when the pressure in the compressor dome A is set to a low pressure, when the oil in the oil separator M is injected into the compression element B, the pressure in the dome A is low, so that the oil is compressed from the compression element B into the compressor dome A. May leak and the amount of oil recovered in the oil separator M may decrease, and the amount of oil in the oil separator M may become insufficient. A part of the oil pumped up in is supplied to the injection passage K2 connected to the oil separator M.

In this case, part of the oil pumped up from the oil pump J is sent to the injection passage K2 through the first auxiliary passage Q1 and the rest is sent to the suction line E through the second auxiliary passage Q2. And each auxiliary passage Q1, Q2
Are provided with throttles P, P that control the flow rate of oil.

However, in the case of the structure shown in FIG. 6, the injection passage K2 and each auxiliary passage Q are provided.
Since the diaphragms P, P, P have to be provided in 1, Q2, the parts cost becomes high, the piping configuration becomes complicated, the piping work becomes difficult, and the number of pipes increases, so that the cost further increases. There is also an oil separator M
Since the structure is such that the oil is positively accumulated in the oil separator M, when the oil is excessively accumulated in the oil separator M, the oil flows to the expander G side, and the oil flows into the expander G. Therefore, there is a problem that the refrigerating capacity is lowered.

Further, in both cases of FIG. 5 and FIG. 6, since the amount of oil mixed in the discharge gas discharged from the compressor D is large, the heat exchange amount in the cooler R is small due to the oil. It was a cause of the deterioration of the freezing capacity.

By the way, the inventor of the present invention measures the value of the oil pump performance and the leakage amount of oil injected into the compression element into the compressor dome depending on each model and operating conditions. It is understood from the results, and the present invention solves the above problems based on the measurement results, and its purpose is to restrict the pump performance of the oil pump and the leakage amount from the compression chamber of the compression element in accordance with the leakage amount. By adjusting the oil injection amount by the mechanism, the piping configuration is simple and the number of parts can be reduced as much as possible, while the fluctuation of the oil injection amount into the compression element is small and the pipe vibration due to pressure pulsation can be prevented An object of the present invention is to provide a compression unit for a refrigerator that can constantly inject oil and improve the refrigerating capacity.

[0012]

In order to achieve the above object, in the invention described in claim 1, the oil in the compressor dome 12 is pumped up by the oil pump 7, and the compression element 13 is compressed through the injection passage 8. In a compression unit of a refrigerator having a compressor 1 for injecting into a room, a throttle mechanism 82 for controlling an injection oil amount is provided in the injection passage 8 and a discharge line 3 of the compressor 1 is provided.
2 is provided with an oil separator 5 at the bottom of the oil separator 5,
The oil return passage 9 for returning oil is connected to the compressor dome 12.

With this arrangement, the throttle mechanism 82 provided in the injection passage 8 adjusts the amount of injection into the compression chamber in accordance with the oil pump performance and the amount of leakage of the compression element from the compression chamber. Oil can be injected, and moreover,
Since a conventional auxiliary passage for supplying oil to the injection passage 8 is not required, the piping configuration is simple and the number of parts can be reduced as much as possible.

Further, since the injection passage 8 is provided with the throttling mechanism 82, even if the amount of oil pumped by the oil pump 7 varies, the throttling mechanism 82
Since the flow rate is controlled, oil can be made to flow out from the throttle mechanism 82 with less fluctuation and pulsation of the oil amount, and the oil injection into the compression chamber can be suppressed with less fluctuation of the oil amount, and pipe vibration due to pulsation can be prevented. It is possible to constantly inject a proper amount of oil.

Furthermore, since an appropriate amount of oil is injected into the compression chamber by the throttle mechanism 82, the amount of oil mixed in the gas discharged from the compressor 1 can be reduced as much as possible, so that the heat exchange amount of the discharged gas also increases. , The refrigeration capacity is improved,
The amount of oil stored in the oil separator 5 can be minimized, the oil can be prevented from flowing out of the oil separator 5 to the expander side, and the refrigerating capacity of the expander can be prevented from lowering.

Further, the throttle mechanism 82 can be specifically realized by means of an orifice, a capillary tube, a variable valve capable of changing the flow rate, and the like.

According to a second aspect of the present invention, in the first aspect of the invention, an auxiliary oil return passage 94 for returning excess oil to the compressor dome 12 is located at a position higher than the bottom oil return port 51 of the oil separator 5. Was connected.

As a result, even when a large amount of oil is stored in the oil separator 5 at the time of starting the compressor 1 and the oil level in the oil separator 5 is likely to fluctuate, excess oil in the oil separator 5 is generated. The oil can be immediately returned to the compressor dome 12 through the auxiliary oil return passage 94 to prevent the oil from flowing out from the oil separator 5 to the expander side.

Therefore, during normal operation, the gas in the compression chamber is satisfactorily cooled, and while the amount of oil in the oil separator 5 is minimized, excess oil is accumulated in the oil separator 5 during startup. When the oil is discharged from the auxiliary oil return passage 94, the compressor dome 1
It can be immediately returned to 2 and the operation at the time of startup can be performed well.

According to a third aspect of the invention, in the first or second aspect of the invention, the throttle mechanism 82 is constituted by a capillary tube.

As a result, the cost can be reduced as compared with the case where the orifice is used.

According to a fourth aspect of the invention, in the first or second aspect of the invention, the throttle mechanism 82 is constituted by a variable valve whose opening degree can be adjusted according to the temperature of the discharge gas.

As a result, the amount of oil injected into the compression chamber can be controlled according to the temperature of the discharged gas, so that the gas can be cooled more efficiently.

As a means for detecting the discharge gas temperature,
Specifically, this can be achieved by providing a discharge gas temperature sensor in the discharge line 32 and detecting the discharge gas temperature, and by controlling the opening of the variable valve based on the detection result, the oil injection amount is controlled. It

According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the diaphragm mechanism 8 is used.
2 is provided near the entrance of the injection passage 8.

As a result, the pressure pulsation of the oil can be suppressed near the inlet of the injection passage 8 immediately after leaving the compressor 1, so that the pipe vibration due to the pressure pulsation in the injection passage 8 can be better prevented. .

[0027]

FIG. 1 shows a first embodiment of the present invention.
It will be described based on. The compression unit shown in FIG. 1 includes a compressor 1 in which a scroll-type compression element 13 and a motor 14 are installed in a low-pressure compressor dome 12 having an oil sump 11 at the bottom, and a cryogenic expander 2. .

The compression element 13 is interlocked with the motor 14 via a drive shaft 15, and the compressor dome 12
A low-pressure helium gas is introduced into the dome 12 from a suction line 31 opening inside, and in the compression element 13,
The low-pressure gas is compressed and the high-pressure helium gas is discharged to the discharge line 32.

The discharge line 32 is connected to the cryogenic expander 2 via the cooler 4, the oil separator 5 and the absorber 61. Although the cooler 4 is not shown,
It is an air-cooling type cooler in which a fan is arranged.

Further, in this cryogenic expander 2, high pressure helium gas is expanded so that the heat stage of the expander 2 becomes an extremely low temperature of 4K to 20K in absolute temperature.

In the cryogenic expander 2, the expanded low pressure helium gas is returned to the compressor dome 12 via the suction line 31. A surge volume 62 is provided near the compressor 1 in the suction line 31.

Further, in the compressor dome 12, a positive displacement oil pump 7 such as a trochoid pump for pumping the oil in the oil sump 11 is provided at the lower end of the drive shaft 15, and the oil pump 7 is compressed. The injection passage 8 taken out of the machine dome 12 is connected.

The injection passage 8 is provided with a filter 81 and a throttle mechanism 82 composed of an orifice. The cooler 4 for cooling the discharge line 32 is provided downstream of the throttle mechanism 82 in the injection passage 8. The oil flowing in the injection passage 8 is cooled and the injection passage 8 is cooled by the compression element 13 as well.
To the compression chamber of the compression element 13. The filter 81 and the throttle mechanism 82 are provided near the inlet of the injection passage 8, that is, near the connecting portion to the compressor 1.

The throttling amount of the throttling mechanism 82 provided in the injection passage 8 depends on the performance of the oil pump 7 and the leakage amount of the oil injected into the compression chamber of the compression element 13 into the low pressure dome 12 in the compression chamber. The throttling amount is set so that the oil is not broken and the oil mixed in the discharge gas is reduced as much as possible.

An oil return passage 9 is connected to the bottom of the oil separator 5, and the oil return passage 9 is connected to the suction line 3.
Connected to the downstream side of the surge volume 62 in 1,
The oil accumulated in the oil separator 5 is returned to the suction line 31 via the oil return passage 9, and the compressor dome 1 is returned from the suction line 31.
The motor 14 in the compressor dome 12 is cooled by returning the oil to the inside of the compressor dome 12.

The oil return passage 9 is also provided with a filter 91 and an orifice 92 serving as a throttle to suppress the amount of oil returned from the oil separator 5.

Then, in the first embodiment of the present invention, the high pressure gas discharged from the compression element 13 to the discharge line 32 is cooled in the cooler 4 and then supplied into the oil separator 5 to be discharged from the high pressure gas. The oil is separated, and the separated gas is introduced into the cryogenic expander 2 and expanded, and then the suction line 3
1 back into the compressor dome 12.

Further, the oil in the oil sump 11 of the compressor dome 12 is pumped up by the oil pump 7 and supplied to the injection passage 8, and the throttle mechanism 82 provided in the injection passage 8 provides a predetermined oil injection amount. After the control, the oil is cooled in the cooler 4 and injected into the compression chamber of the compression element 13 to cool the gas in the compression chamber.

The oil pumped up by the oil pump 7 has a throttle mechanism 8 in which the amount of pumped oil is controlled by the throttle mechanism 82.
2 is larger than the passing amount of 2, the pumping oil partially overflows from the gap of the oil pump 7 and the oil sump 11
I will try to collect it again.

The amount of oil injected into the compression chamber is controlled to an appropriate amount, but since the discharge gas contains a little oil, the mixed oil is separated by the oil separator 5. The separated oil is returned to the compressor dome 12 through the oil return passage 9 while cooling the motor 14.

As described above, the amount of oil injected from the injection passage 8 into the compressor chamber is adjusted to a predetermined amount by the throttle mechanism 82 in accordance with the oil pump performance and the amount of leakage of the compression element from the compression chamber. By setting, it is possible to inject an appropriate amount of oil into the compression chamber so that excess oil is not injected, and the oil separated by the oil separator 5 is immediately passed through the oil return passage 9 to the compressor. Since the oil is collected in the dome 12, the amount of oil in the oil sump 11 in the dome 12 does not extremely decrease.

Moreover, the discharge line 32 and the suction line 31
Since the pipes other than the above can be used only for the injection passage 8 and the oil return passage 9, there is no need for an auxiliary passage for supplying oil to the injection passage 8 unlike the conventional case, and the piping structure can be simplified, and Since the throttles provided in each pipe can be reduced accordingly, the number of parts can be reduced as much as possible and the cost can be reduced.

Further, since the injection passage 8 is provided with the throttling mechanism 82, even if the amount of oil pumped by the oil pump 7 varies, the throttling mechanism 82
Since the flow rate is controlled, oil can be made to flow out from the throttle mechanism 82 with less fluctuation and pulsation of the oil amount, and the oil injection into the compression chamber can be suppressed with less fluctuation of the oil amount, and pipe vibration due to pulsation can be prevented. It is possible to constantly inject a proper amount of oil.

Further, since an appropriate amount of oil is injected into the compression chamber by the throttle mechanism 82, the amount of oil mixed in the gas discharged from the compressor 1 can be reduced as much as possible. Therefore, the heat of the discharge gas in the cooler 4 can be reduced. The exchange amount is increased, the refrigeration capacity is improved, and the oil stored in the oil separator 5 can be minimized.
It is possible to prevent the oil from flowing out from the oil separator 5 to the expander side, and prevent the refrigerating capacity of the expander from decreasing.

Since the throttle mechanism 82 is provided near the inlet of the injection passage 8 to control the oil flow rate, the oil pressure pulsation of the oil pump 7 causes the oil pressure pulsation immediately after exiting the compressor 1 from the injection passage. Since it can be suppressed near the inlet of 8, the pipe vibration due to the pressure pulsation in the injection passage 8 can be better prevented.

By providing the throttle mechanism 82 further on the compressor side than the arrangement position shown in FIG. 1, it is possible to better prevent pipe vibration due to pressure pulsation.

Next, a second embodiment will be described with reference to FIG. The second embodiment uses the oil separator 5 of the first embodiment,
Furthermore, an auxiliary oil return passage 94 is connected, and the auxiliary oil return passage 94 is located at a higher position than the bottom oil return port 51 of the oil separator 5 connecting the oil return passage 9. The position of the filter 91 and the orifice 9
2 is provided to return excess oil from the suction line 31 to the compressor dome 12.

The amount of oil accumulated in the oil separator 5 is
Since the amount of oil injected from the injection passage 8 is adjusted to an appropriate amount by the throttle mechanism 82, it can be minimized. However, when the compressor 1 is started after being stopped for a long time, the oil separator 5 There is a case where a large amount of oil is stored in the inside, and when the oil separator 5 is started in such a state where a large amount of oil is stored in this way, the oil level in the oil separator 5 easily fluctuates, and the expander is expanded. Since there is a possibility that oil will flow out to the second side, excess oil in the oil separator 5 will be immediately removed from the auxiliary oil return passage 94.
So that oil is returned to the inside of the compressor dome 12 via
I am able to return to normal operation immediately.

By doing so, during normal operation, gas is satisfactorily cooled in the compression chamber, and the oil separator 5
Although the amount of oil stored in the oil separator can be minimized, the oil can be immediately returned to the compressor dome 12 from the auxiliary oil return passage 94 when excessive oil is accumulated in the oil separator 5 at the time of start-up. Therefore, the operation at the time of startup can be performed well.

Next, a third embodiment will be described with reference to FIG. In the above-described first embodiment, the throttle mechanism 82 provided in the injection passage 8 is constituted by the orifice and the throttle of the oil return passage 9 is also constituted by the orifice 92, but in the third embodiment, the capillary tube is used instead of these orifices. Is used.

As described above, by using the throttle mechanism 82 provided in the injection passage 8 as the capillary tube and the throttle of the oil return passage 9 as the capillary tube 93, the cost can be reduced as compared with the case of using the orifice. .

Further, a fourth embodiment will be described with reference to FIG. In the fourth embodiment, the throttling mechanism 82 is composed of a variable valve whose opening degree can be adjusted according to the discharge gas temperature.

Specifically, a throttle mechanism 82 including a filter 81 and a variable valve is provided on the inlet side of the injection passage 8.
On the other hand, a discharge gas temperature sensor 83 for detecting the discharge gas temperature is arranged near the outlet of the compressor 1 in the discharge line 32, and the temperature detection result of the discharge gas temperature sensor 83 is sent to the controller 84. Then, by adjusting the opening degree of the variable valve connected to the controller 84 by a command from the controller 84 based on the discharge gas temperature detection result, the flow rate of the throttle mechanism 82 is controlled to inject oil into the compression chamber. I try to control the amount.

By doing so, the opening of the variable valve is controlled in accordance with the discharge gas temperature detected by the discharge gas temperature sensor 83 to control the flow rate of the throttle mechanism 82, so that the oil flow to the compression chamber is reduced. Since the injection amount can be constantly controlled according to the discharge gas, the gas can be cooled more efficiently.

[Brief description of drawings]

FIG. 1 is a piping configuration diagram showing a first embodiment of a compression unit of a refrigerator of the present invention.

FIG. 2 is a piping configuration diagram showing a second embodiment of the compression unit of the refrigerator of the present invention.

FIG. 3 is a piping configuration diagram showing a third embodiment of the compression unit of the refrigerator of the present invention.

FIG. 4 is a piping configuration diagram showing a fourth embodiment of the compression unit of the refrigerator of the present invention.

FIG. 5 is a piping configuration diagram of a compression unit of a conventional refrigerator.

FIG. 6 is a piping configuration diagram of a compression unit of another conventional refrigerator.

[Explanation of symbols]

 1 Compressor 12 Compressor Dome 32 Discharge line 5 Oil separator 51 Bottom oil return passage 7 Oil pump 8 Injection passage 82 Throttling mechanism 9 Oil return passage 94 Auxiliary oil return passage

Claims (5)

[Claims] 1. A compressor (1) for pumping oil in a compressor dome (12) with an oil pump (7) and injecting it into a compression chamber of a compression element (13) through an injection passage (8). A compressor unit for a refrigerator, wherein a throttle mechanism (82) for controlling an injection oil amount is provided in the injection passage (8), and oil is separated in a discharge line (32) of the compressor (1). Bowl (5)
A compressor unit for a refrigerator, characterized in that an oil return passage (9) for returning oil to the compressor dome (12) is connected to the bottom of the oil separator (5) via the. 2. An auxiliary oil return passage (94) for returning excess oil to the compressor dome (12) is connected to a position higher than the bottom oil return port (51) of the oil separator (5). The compression unit of the refrigerator according to 1. 3. The compressor compression unit according to claim 1, wherein the throttle mechanism (82) is a capillary tube. 4. A compression unit for a refrigerator according to claim 1 or 2, wherein the throttle mechanism (82) comprises a variable valve whose opening can be adjusted according to the temperature of the discharged gas. 5. A throttle mechanism (82) is provided near the inlet of the injection passage (8).
The compression unit of the refrigerator according to any one of 1.