JPH0120697B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a refrigeration system using a compressor.
This relates to a device that returns oil mixed in refrigerant in a low pressure section to a compressor.

For example, in a refrigeration system using a conventional screw compressor, as shown in FIG.
2. In a refrigerator in which a refrigeration cycle is formed by an outlet pipe 33, a steam pipe 42, and an intake pipe 30,
In order to return the oil accumulated in the evaporator 17 to the screw compressor 1, the discharge pipe 31 to the suction pipe 30 are connected by bypass pipes 40, 41, and the ejector 14 is provided in the bypass path formed by these bypass pipes. , the suction section 38 of the ejector 14 and the evaporator 17 are connected by an oil return pipe 37. The oil-containing refrigerant liquid in the evaporator 17 is sucked into the ejector 14 by the flow through the bypass pipes 40 and 41 and returned to the screw compressor 1 via the suction pipe 30. Note that 16 is an expansion valve.

However, in conventional systems with this type of structure, the refrigerant gas that has been pressurized to the discharge pressure by the screw compressor is returned to the suction side for suction, which increases wasteful compression work that is useless for the refrigeration cycle. The defects that led to a decline in efficiency were corrected. The present invention cools the refrigerant liquid entering the evaporator with an economizer, takes out a part of the intermediate pressure refrigerant gas after evaporation, and guides it to the suction side of the compressor via the ejector. By suctioning the oil-containing refrigerant liquid and returning it to the rotor working space, it is less wasteful than a system that uses discharged gas, although the above-mentioned drawbacks of conventional systems cannot be completely eliminated. The reduction in compression work was previously aimed at providing an oil return device for a refrigeration system that could improve efficiency.

FIG. 2 shows a first embodiment of the invention, in which the refrigerant is compressed in a screw compressor 1 and goes to an oil separator 11 through a discharge pipe 31. The separated oil is pumped by the oil pump 12, goes to the oil cooler 13 through the oil pipe 34, goes to the bearing oil supply hole 3 of the screw compressor through the oil pipe 35, and goes through the oil pipe 36 installed in parallel. Go to oil injection hole 2.

After separating the oil in the oil separator, the refrigerant gas goes to the condenser 15 through the discharge pipe 32, and the condensed refrigerant liquid goes through the heat exchanger 18, goes through the pipe 43 to the economizer 61, and then passes through the condenser float. 62
through the opening 63 to the economizer float chamber 64
The water enters the tank, passes through the economizer float 65, goes to the evaporator 17 via piping 44, and is evaporated there. The refrigerant gas returns to the suction hole 51 of the screw compressor 1 through the suction pipe 50. A branch 46 is provided in the upper gas phase part of the economizer float chamber, and the gas passes from there through a bypass pipe 47, a solenoid valve 66, a thermostatic automatic expansion valve 16, an ejector 14, and a bypass pipe 48. , joins the suction pipe 50 at a junction 49 . This temperature-type automatic expansion valve 16 has a temperature-sensitive cylinder 60
controlled by the temperature sensed by the

The oil-rich refrigerant holding portion of the evaporator is connected to the suction portion 38 of the ejector 14 via the heat exchanger 18 by an oil return pipe 37. The economizer float chamber 64 is connected to the screw compressor 1 by an intermediate suction pipe 70 having a back pressure regulating valve 71.
The back pressure thereof is regulated.

FIG. 3 shows another embodiment in which the type of economizer 61 is different from that in FIG. 2, but the same reference numerals as in FIG. 2 indicate the same parts.

In FIG. 3, the refrigerant liquid leaving the condenser 15 is
The economizer 6 is sealed from the outlet pipe 33 to the piping 43.
1, some of which are branched in parallel from piping 43' to economizer 6 via thermostatic automatic expansion valve 16.
1 and flashes, supercooling the refrigerant liquid coming from the pipe 43.

The supercooled refrigerant liquid passes through the heat exchanger 18 and enters the evaporator 17 . 75 is a refrigerant flow control valve, and 76 is a liquid level regulator. The gas phase part of the economizer 61 branches from the intermediate suction pipe 70, and is connected to the pipe 47 and the solenoid valve 6.
6. The thermostatic automatic expansion valve 16 is connected to the ejector 38, and is further connected to the bypass pipe 48,
Refrigerant gas suction pipe 50 from evaporator 17 and confluence point 4
9 and return to the screw compressor at the suction opening 51. Also, the gas phase part of the economizer is equipped with a back pressure regulating valve 7.
1, the compressor is sucked into the compressor through the intermediate suction opening 72 of the screw compressor 1. At this time, the economizer pressure is maintained at a constant pressure by the back pressure regulating valve. . As in the case of FIG. 2, the refrigerant liquid containing oil from the evaporator 17 passes through the heat exchanger 18 through the pipe 37 and reaches the suction point 38 of the ejector 14.

Since the above embodiment is constructed as described above, it has the following remarkable effects.

1 The economizer in the economizer cycle cools the refrigerant liquid entering the evaporator (increasing the refrigeration effect), and uses the evaporated intermediate pressure gas to actuate the ejector, which results in unnecessary compression compared to systems that use discharged gas. Work will be reduced.

2. A heat exchanger is installed in the middle of the oil return pipe to exchange heat between the oil-containing refrigerant in the low-pressure part of the refrigeration system and the high-pressure refrigerant liquid before flowing into the low-pressure part, thereby subcooling the high-pressure refrigerant liquid and freezing it. Increase effectiveness and increase coefficient of performance of refrigerator.

In addition, as the compressor, in addition to the screw compressor, a positive displacement compressor such as a rotary vane type, rotary piston type, or Roots type may be used. In addition, even non-oil injection type devices may be used for collecting oil from bearings, etc.

The present invention includes compressors, condensers, economizers,
In a refrigeration system that forms a refrigeration cycle by an evaporator and a refrigerant path connecting these, a branch point is provided in a part of the gas phase part of the economizer or intermediate suction line to branch a bypass path, and the other end of the bypass path is An ejector is connected to the suction side of the compressor and inserted in the middle of the bypass path, and the suction part of the ejector and the refrigerant liquid holding part containing oil in the low pressure system of the refrigeration system are connected through an oil return path. As a result of this communication, it is possible to provide an oil return device for a refrigeration system that can reduce wasteful compression work and improve efficiency, which has an extremely large practical effect.

[Brief explanation of drawings]

FIG. 1 shows a flow sheet of a conventional example of a refrigeration system, FIG. 2 shows a flow sheet of an embodiment of the present invention, and FIG. 3 shows a flow sheet of another embodiment. Explanation of symbols, 1... Screw compressor, 2...
Oil injection hole, 3... bearing oil supply hole, 11... oil separation,
12...Oil pump, 13...Oil cooler, 14...
Ejector, 15... Condenser, 16... Temperature type automatic expansion valve, 17... Evaporator, 18... Heat exchanger, 3
1, 32, 33...discharge pipe, 34, 35, 36...
... Oil pipe, 37 ... Oil return pipe, 38 ... Ejector suction section, 43, 47 ... Piping, 48 ... Bypass pipe, 60 ... Temperature sensing cylinder, 61 ... Economizer, 62 ... Condenser float, 63...Opening, 64...Economizer float chamber, 65...
...Economizer float, 66...Solenoid valve, 7
0... Intermediate suction pipe, 71... Back pressure regulating valve, 72...
...Inhalation opening.

Claims (1)

[Claims] 1. In a refrigeration system in which a refrigeration cycle is formed by a compressor, a condenser, an economizer, an evaporator, and a refrigerant path connecting these, a branch point is provided in a part of the gas phase part of the economizer, and A bypass path consisting of bypass piping is branched from the bypass path, the other end of the bypass path is connected to the suction side of the compressor, and an ejector is inserted in the middle of the bypass path, and the suction section of the ejector and the inside of the evaporator are connected to each other. An oil return device for a refrigeration system, characterized in that the oil return device is connected to a refrigerant liquid holding portion containing oil through an oil return pipe. 2 In the bypass route, a thermostatic automatic expansion valve is provided between the branch point and the ejector, and a bypass piping or compressor is provided between the ejector in the bypass route and the suction side of the compressor. The above patent claim is characterized in that the discharge pipe of the machine is equipped with a temperature detector that detects the temperature, and a control mechanism that controls the opening degree of the temperature-type automatic expansion valve based on a signal from the temperature detector. The oil return device according to item 1. 3. A heat exchanger is provided in the middle of the oil return pipe that connects the refrigerant liquid holding part in the evaporator and the suction part of the ejector, and the heat exchanger contains oil passing through the oil return pipe. 2. The oil return device according to claim 1, wherein the oil return device is configured to exchange heat between the refrigerant liquid from the high pressure side and the refrigerant liquid from the high pressure side.