JPS633226B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a refrigeration system in which a lubricating oil is mixed with a refrigerant and circulated through a cycle, and is effective when used, for example, as a system for air conditioning the interior of an automobile. In refrigeration systems, compressors require lubricating oil to lubricate sliding parts such as cylinders and bearings, but in refrigeration systems used for automobile air conditioning, the compressor is usually located inside the engine room. Especially in recent years,
Engine rooms are becoming increasingly narrow due to exhaust gas countermeasure equipment, and a lighter weight ratio of the compressor is desired to improve fuel efficiency, so there is a strong demand for the compressor 1 to be smaller and lighter.

Therefore, recent compressors 1 are not equipped with oil pumps or large oil reservoirs, which increase weight, and instead lubricate the lubricated parts by mixing lubricating oil into the refrigerant and compressing and discharging it. Therefore, the refrigerant discharged from the compressor contains lubricating oil.

However, in order to perform lubrication by mixing lubricating oil into the refrigerant, a sufficient amount of lubricating oil must be supplied to the compressor even when the amount of refrigerant circulating in the cycle is insufficient. In order for the refrigerant to return, a large amount of lubricating oil must be mixed in with the refrigerant, and in conventional systems, the weight of lubricating oil (lubricating oil content) was about 4 to 9%.

However, since this lubricating oil has different properties such as condensation and evaporation from the refrigerant, it impairs the performance of the condenser 3, evaporator 6, etc. and deteriorates the performance of the refrigeration system.

Therefore, the present inventors varied the lubricating oil content and investigated the effect of the amount of circulating lubricating oil on the compressor, and found that in the steady operating range of the refrigeration equipment where the refrigerant is sufficiently circulated throughout the cycle, Oil content 2
%, it was confirmed that no problems such as poor sliding occurred in the compressor 1.

Therefore, in the refrigeration system of the present invention, an oil separator is installed on the outlet side of the compressor, and this oil separator temporarily separates the lubricating oil from the refrigerant, and the separated lubricating oil is reduced to the minimum amount necessary for lubrication of the compressor. Only the amount of lubricating oil (the amount that makes the lubricating oil content 2%) is introduced into the condenser side.

That is, an object of the present invention is to provide a refrigeration system that can always flow the necessary minimum amount of lubricating oil to a compressor regardless of the amount of circulating refrigerant.

Figure 1 is a schematic diagram of a refrigeration system. In the figure, 1 is a compressor that compresses and discharges refrigerant, 3 is a condenser that condenses the refrigerant, and 4 is a condenser that converts the liquefied refrigerant into a gas phase and a liquid. 5 is an expansion means for introducing only liquid refrigerant from the liquid receiver 4 and expanding it into a low-temperature, low-pressure mist; and 6 is an evaporator for evaporating the refrigerant. When the refrigerant evaporates in the evaporator 6, it absorbs the heat of vaporization from the air and performs cooling.

FIG. 2 is a sectional view showing the structure of this oil separator 2. In the figure, 7 is an upper housing made of aluminum, and 8 is a lower housing also made of aluminum. These housings 7 and 8 are both formed into a cylindrical shape and are brazed to each other, forming an oil separation chamber 11 in the upper part and an oil storage chamber 12 for storing the separated lubricating oil in the lower part. It is beginning to form. In addition, the upper housing 7
An inlet pipe 9 for introducing the refrigerant discharged from the compressor 1 is provided in such a manner that its open end 9a faces in the tangential direction, and the lower housing 8 leads the refrigerant to the inlet pipe 3a of the condenser 3. A lead-out pipe 10 is brazed so that its open end 10a opens at the center above the housing 7.

Therefore, the refrigerant introduced into the oil separation chamber 11 from the introduction pipe 11 swirls along the side walls of the housings 7 and 8, and at this time, the lubricating oil having a large mass collides with the side walls due to centrifugal force, causing dew condensation. The refrigerant from which the lubricating oil has been removed flows into the inlet pipe 1.
0 leads to condensation 3.

In addition, a restriction 13 with a diameter of about 1 mm is provided at the bottom of the lower housing 8 in the lead-out pipe 10 at a position communicating with the oil storage chamber 12. This aperture 13
The refrigerant is mixed into the outlet pipe 10 and flows out to the condenser 3 together with the refrigerant in the outlet pipe 10. A filter 14 covers the outer periphery of the aperture 13 and is made of a fine mesh to prevent foreign matter such as metal powder from flowing toward the condenser 3 together with the lubricating oil.

The oil separator 2 having the above configuration is fixed to the bracket 3b of the condenser 3 with screws 15a via the mounting bracket 15. Since the refrigeration system of the present invention is provided with such an oil separator 2,
The lubricating oil that circulates within the cycle is limited to that which has passed through the throttle 13. As a result, under normal operating conditions, excess lubricating oil is stored in the oil storage chamber 12, and only the minimum amount of lubricating oil necessary flows into the cycle. There will be no. Particularly in this case, the amount of lubricating oil passing through the throttle 13 will change depending on the pressure difference before and after the throttle 13, so when the amount of refrigerant passing through the outlet pipe 10 increases and the refrigerant flow rate increases, it will flow out accordingly. The amount of lubricating oil also increases, and as a result, the lubricating oil content is always maintained constant.

Here, as shown in Fig. 3, it has been considered to return the lubricating oil stored in the oil storage chamber 12 of the oil separator 2 directly to the inlet side of the compressor 1, but such Special passage 16 for returning oil
A special shutoff valve 17 or the like is required to close this passage 16 when the compressor 1 is stopped or the compressor 1 is stopped, resulting in problems such as increased production costs of the refrigeration system and difficulty in assembly. . On the other hand, in the refrigeration system of the present invention, as described above, the lubricating oil in the oil storage chamber 12 is made to flow to the condenser 3 side, so such a problem does not occur at all.

Furthermore, in the device shown in FIG. 3, the oil storage chamber 12 and the compressor 1
Since there is a large pressure difference between the inlet side and the inlet side, the orifice 18 that limits the amount of lubricant returned must be made quite small, making it difficult to manufacture and prone to problems such as clogging. In this refrigeration system, since there is not a very large pressure difference between the oil storage chamber inlet and the condenser 3 inlet, the diameter of the orifice 13 does not need to be made very small, and therefore such a problem does not occur.

Next, we will explain what happens when a refrigerant shortage occurs in the refrigeration system for some reason. In such a case, the amount of refrigerant and lubricating oil introduced into the oil separator 2 through the introduction pipe 9 decreases, so there is a shortage of refrigerant in the oil storage chamber 12. The amount of lubricating oil flowing out is greater than the amount of lubricating oil flowing in, and the lubricating oil is not stored in the oil storage chamber 12, and the lubricating oil stored in the oil storage chamber 12 moves to the inlet side of the compressor 1 and is used as a low-pressure side refrigerant. This will accumulate in the pipes and evaporator 6. Therefore, even if there is a slight shortage of refrigerant, the lubricating oil stored in the low-pressure side refrigerant pipe and the evaporator 6 is sequentially returned to the compressor 1, and the compressor 1 can be well lubricated.

This shows that a refrigerant shortage condition can be determined by checking the amount of lubricating oil in the oil storage chamber 12, and if a sight glass is installed in the housing 8, the refrigerant shortage condition can be directly detected. It can be visually checked, and maintenance and inspection of the refrigeration equipment can be easily performed.

In the above example, the oil separator 2 that separates lubricating oil by creating a swirling flow in the refrigerant was used, but other types of oil separators 2, such as the introduction pipe 9 It is also possible to use an arrangement in which a collision object such as a shade is disposed at a position opposite to the opening end 9a, and the lubricating oil is separated by colliding the refrigerant with the collision object. Especially oil separator 2 used in the device of the present invention
Since a very good oil separation ability is not required, it is desirable to use one with the simplest possible structure.

Further, in the above example, the oil separator 2 was fixed to the condenser 3, but the oil separator 2 is fixed to the compressor 1.
It is only necessary to dispose it between the condenser 3 and the condenser 3, and it goes without saying that it may be fixed to something other than the condenser 3, such as the body of an automobile.

As explained above, the device of the present invention uses an oil separator to temporarily separate the lubricating oil from the refrigerant discharged from the compressor, and then sends the separated lubricating oil to the condenser through the throttle. During operating conditions, excess lubricating oil can be stored in the oil separator so that only a small amount of lubricating oil passes through the throttle during the cycle, thereby eliminating unnecessary lubricating oil during normal operation. It is possible to avoid a situation where a large amount of lubricant oil is poured into the cycle and reduce the capacity of the refrigeration system.In addition, in the case of a refrigerant shortage, the lubricant oil stored in the oil separator can be diverted to the compressor inlet side. It has the excellent effect of being able to extremely effectively prevent sliding failures of the compressor by moving the compressor.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram showing an example of the apparatus of the present invention, Fig. 2 is a partial sectional view showing main parts of an embodiment of the apparatus of the present invention, and Fig. 3 is a schematic diagram showing a conventional refrigeration apparatus. FIG. 1... Compressor, 2... Oil separator, 3... Condenser, 5... Expansion means, 6... Evaporator, 13... Throttle.

Claims (1)

[Claims] 1. A compressor that compresses and discharges a refrigerant containing lubricating oil, an oil separator that separates lubricating oil from the refrigerant discharged from the compressor, a condenser, an expansion means, and an evaporator are connected to refrigerant piping. A refrigeration system characterized in that a constrictor is arranged in a pipe connecting the oil storage chamber of the oil separator and the condenser.