JPH063335Y2 - Oil return mechanism of ultra low temperature refrigeration circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an oil return mechanism of an ultra-low temperature refrigeration circuit for returning the lubricating oil separated by an oil separator to a hermetic compressor.

(Prior Art) Conventionally, in an ultra-low temperature refrigeration circuit in which the refrigerant temperature on the evaporator side significantly decreases, if lubricating oil of a hermetic compressor is mixed in the refrigerant, the viscosity of the lubricating oil on the evaporator side will increase significantly. It may become high and hinder the circulation of the refrigerant. In order to prevent this, an oil separator is attached to the refrigeration circuit to separate the lubricating oil in the refrigerant and return it to the hermetic compressor.

As such an oil return mechanism, as shown in FIG. 2, an oil separator 3 is provided in the middle of the discharge pipe 2 of the hermetic compressor 1, and the lubricating oil separated by the oil separator 3 is returned to the oil. It is known to return to the suction pipe 5 via the pipe 4.

According to this oil return mechanism, since the oil separator 3 has a high pressure due to the discharged refrigerant and the suction pipe 5 has a low pressure, the lubricating oil in the oil separator 3 has a high pressure due to this pressure difference. It returns to the hermetic compressor 1 through the suction pipe 5.

(Problems to be solved by the invention) However, in the oil return mechanism of the conventional ultra-low temperature refrigerant circuit, the refrigerant of about −40 ° C. to −50 ° C. flows in the suction pipe 5, and therefore the lubrication flowing in the suction pipe 5 There is a problem that the viscosity of the oil becomes very high, the circulation of the refrigerant in the suction pipe 5 is obstructed, and the cooling efficiency is lowered.

In order to solve such a problem, the conventional method 52
An oil return mechanism for a refrigeration circuit (not shown) disclosed in Japanese Patent Laid-Open No. 67056 has been proposed.

In this oil return mechanism, the oil return pipe is directly connected to the crankcase of the compressor, and the lubricating oil of the oil separator is directly returned to the compressor.

However, in general, an ultra-low temperature hermetic compressor does not have a preliminarily prepared connecting portion for connecting the oil return pipe to the compressor itself, and therefore, when connecting the oil return pipe to the compressor, The compressor must be modified to form an oil return connection on the side wall of the crankcase, which has been a problem in that it takes time to modify the compressor.

Also, in a hermetic compressor that is a pressure vessel, installation of a pipe connecting part, etc. should be avoided as much as possible due to its airtightness, pressure resistance, etc., and the latter oil return mechanism must satisfy this requirement. I couldn't.

In view of the above-mentioned conventional problems, the object of the present invention is to achieve a very low temperature at which lubricating oil can be smoothly returned to the hermetic compressor by using a filling pipe for refrigerant filling which is not used during operation of the refrigeration circuit. It is to provide an oil return mechanism for a refrigeration circuit.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides a filling pipe for charging a refrigerant, which communicates with a low pressure part of a hermetic compressor, and a discharge pipe which communicates with a high pressure part of the hermetic compressor. And an oil separator that separates the lubricating oil of the hermetic compressor from the discharge pipe, and the lubricating oil separated by the oil separator is returned to the hermetic compressor through an oil return pipe. In the oil return mechanism of the circuit, the oil return pipe is connected to the filling pipe.

According to the present invention, since the oil return pipe is connected to the filling pipe, the lubricating oil in the oil separator returns to the low pressure part of the hermetic compressor through the oil returning pipe and the filling pipe due to the pressure difference. Since the temperature of the filling pipe is high due to the conduction heat from the hermetic compressor, the viscosity of the lubricating oil does not increase.

(Embodiment) FIG. 1 shows an embodiment of an oil return mechanism of an ultra-low temperature refrigeration circuit according to the present invention, and the same components as those of the conventional example are represented by the same reference numerals. That is, reference numeral 1 denotes a hermetic compressor, for example, a reciprocating hermetic compressor, which stores a predetermined amount of lubricating oil in the lower crankcase 1a and performs a lubricating action of a piston mechanism (not shown). Intake gas flows into the crankcase 1a, and the pressure is lower than that on the piston head side (high pressure portion) (low pressure portion). Further, the crankcase 1a has a high temperature due to the driving of the piston mechanism. Reference numeral 2 is a discharge pipe, one end of which is connected to the piston head side of the hermetic compressor 1 and the other end of which is connected to a condenser so that high-pressure refrigerant is discharged to the condenser. Reference numeral 3 is an oil separator provided in the middle of the discharge pipe 2 for separating lubricating oil from the refrigerant discharged from the hermetic compressor 1. 4 ″ is an oil return pipe, one end of which is connected to the bottom of the oil separator 3 and the other end of which is connected to a filling pipe 6 which will be described later so that the lubricating oil separated by the oil separator 3 flows into the filling pipe 6. 5 is a suction pipe, one end of which is an evaporator,
The other ends are connected to the crankcase 1a, respectively, and the intake gas flowing out from the evaporator is returned to the hermetic compressor 1. Reference numeral 6 is a filling pipe for filling the refrigerant, one end of which is connected to the crankcase 1a and the other end is sealed.

According to this embodiment, one end of the filling pipe 6 is connected to the crankcase 1a, the other end is connected to the oil return pipe 4 ", and the other end of the filling pipe 6 is sealed. The pressure in 6 becomes the same as that in the crankcase 1a, whereby the lubricating oil in the oil separator 3 returns to the hermetic compressor 1 through the oil return pipe 4 ″ and the filling pipe 6.

Further, since the driving heat in the hermetic compressor 1 is conducted to the filling pipe 6 to increase the temperature, the viscosity of the lubricating oil does not increase and the lubricating oil adheres to the inner wall of the filling pipe 6. Or it does not solidify.

As described above, the oil return mechanism of the ultra-low temperature refrigeration circuit according to the present embodiment does not need to provide the crankcase 1a with the connection part for the oil return pipe as in the conventional case, and can be easily applied to a general-purpose hermetic compressor. Further, when the refrigeration circuit is in operation, the unused filling pipe 6 is effectively used for returning oil, and the filling pipe 6 serves as an oil returning filling pipe.

As described above, according to the present invention, since the oil return pipe is connected to the filling pipe, the lubricating oil in the oil separator returns to the low pressure portion of the hermetic compressor due to the pressure difference. Also, since the temperature of the filling pipe is high due to the conduction heat from the hermetic compressor, the viscosity of the lubricating oil does not increase, and it may adhere to the inner wall of the filling pipe or solidify in the filling pipe. And has the advantage of returning smoothly to the hermetic compressor.

Further, unlike the conventional case, it is not necessary to provide a connecting portion for an oil return pipe in the main body of the compressor, and it can be easily applied to a general-purpose hermetic compressor, and a filling pipe that is not used during operation of an ultra-low temperature refrigeration circuit. Is effectively used for oil return, and this filling pipe serves as an oil return filling pipe.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a piping diagram showing an oil returning mechanism of an ultra low temperature refrigeration circuit, and FIG. 2 is a piping diagram showing an oil returning mechanism of a conventional ultra low temperature refrigeration circuit. In the figure, 1 ... hermetic compressor, 1a ... crankcase, 2 ...
Discharge pipe, 3 ... Oil separator, 4, 4 "... Oil return pipe,
5 ... suction pipe, 6 ... filling pipe.

Claims (1)

[Scope of utility model registration request] 1. A hermetic compressor having a filling pipe for charging a refrigerant, which communicates with a low-pressure portion of a hermetic compressor, and a discharge pipe, which communicates with a high-pressure portion of the hermetic compressor. An oil separator for separating the lubricating oil of the above, and the lubricating oil separated by the oil separator is returned to the hermetic compressor through an oil returning pipe in an oil returning mechanism of an ultra low temperature refrigeration circuit, wherein the oil returning pipe is filled with the oil. An oil return mechanism for an ultra-low temperature refrigeration circuit characterized by being connected to a pipe.