JPS6051025B2 - Accumulator with float-operated expansion device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an expansion device in a refrigeration cycle, and more particularly to an accumulator having a float-operated expansion device.

Most conventional refrigeration systems use thermostatic automatic expansion valves as expansion devices, except for those that use capillary tubes.

As is known, the thermostatic automatic expansion valve operates by providing a heat-sensitive tube at the outlet of the evaporator and adjusting the flow rate of the refrigerant so that the degree of superheat of the refrigerant at this position reaches a set value.

Therefore, as long as a thermostatic automatic expansion valve is used, the refrigerant must be superheated by several degrees at the evaporator outlet.

In order to obtain a superheat degree of several degrees in the evaporator, a fairly large portion of the heat transfer area of the evaporator is required, but on the other hand, this superheat area contributes little to heat transfer because heat transfer is poor.

Therefore, it is desirable to keep this degree of superheating as low as possible.

For example, in the case of a multi-bus evaporator, the distribution of the refrigerant flow rate in each bus is not uniform, and the degree of superheating must be increased to obtain stable operation.

Furthermore, in the case of a refrigeration system with a wide temperature range of refrigeration load, even if the degree of superheating is set to be small at a location where the evaporation temperature is low, the degree of superheating will be excessive at a location where the evaporation temperature is high. As mentioned above, in actual use of thermostatic automatic expansion valves, the superheated region may occupy several tens of percent of the heat transfer area of the evaporator, which hinders miniaturization of the evaporator. .

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide an accumulator with an expansion device that controls the flow rate of refrigerant so that the degree of superheating at the outlet of the evaporator is o.

Therefore, in the present invention, a needle valve and a float are installed in the accumulator, and the float and the valve stem of the needle valve are connected to each other, so that when the liquid level in the accumulator rises, the needle valve moves in the direction of closing, and when the liquid level falls, the needle valve moves in the direction of closing. Made the valve open. The inlet side of this needle valve is connected to the condenser outlet, and the outlet side is connected to the evaporator inlet side. This valve therefore controls the flow of refrigerant to the evaporator so that the liquid level in the accumulator remains constant. Therefore, a certain amount of liquid always returns to the accumulator from the evaporator outlet, and the degree of superheat is maintained at 0 at the evaporator outlet. An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows a refrigeration cycle using the expansion device of the present invention.

The high-temperature, high-pressure refrigerant gas compressed by the compressor 1 is condensed in the condenser 2, expanded by a float-operated expansion device u installed in the accumulator, and sent to the evaporator 3.

The refrigerant evaporated in the evaporator flows into the accumulator 4 in a wet state, operates an internal float, and is sucked into the compressor 1 again.

Next, the structure of the float-operated expansion device installed in the accumulator will be explained in detail with reference to FIG.

A float-operated expansion valve 7 (needle valve), a float 8, and a U-vibe 9 are provided in the accumulator container 6, and the float 8 is connected to the valve stem 11 of the float-operated expansion valve 7 (needle valve) by a rod 10. They are connected via a fulcrum 12 and a pin 13.

Therefore, when the float rises due to the liquid in the accumulator, the valve stem 11 moves in the direction of closing the valve, and when the float falls, it moves in the direction of opening the valve.

The liquid refrigerant at the condenser outlet enters the inlet chamber 15 of the expansion valve (needle valve) from the vibrator 14, passes through the orifice 16, reaches the outlet chamber 17, and is connected to the evaporator inlet by the vibrator 18. Since both the outflow chamber and the inside of the container 6 are at low pressure, sealing the valve stem 11 is not a problem. The refrigerant from the evaporator outlet enters the accumulator 1 through the vibrator 19, the liquid part accumulates in the accumulator, and the gas part is sucked in from the upper end opening of the U-vibe 9 and connected to the compressor suction side. An oil return hole 20 is provided in the lower part of the U-vibe 9, and the liquid refrigerant remaining in the accumulator flows out in a fixed amount from this hole to the compressor.

Stoppers 21 are provided above and below the rod to limit the movement of the float, and the expansion valve 7 (needle valve) is fully closed when the upper stopper is positioned, and fully open when the lower stopper is positioned.

Next, the operation of the expansion valve 7 will be explained.

The expansion valve 7 adjusts the flow rate of refrigerant flowing into the evaporator so that the liquid level is such that the float floats between the upper and lower stoppers.

Further, a certain amount of liquid refrigerant in the accumulator 4 always flows out to the compressor from the oil return hole 20 at the bottom of the U-vibe.

Therefore, in order to maintain the liquid level, the expansion valve supplies refrigerant to the evaporator so that liquid returns from the evaporator in proportion to the outflow amount. Therefore, the degree of superheat is always maintained at O at the outlet of the evaporator.

The same amount of liquid refrigerant returns from the evaporator as the amount of liquid refrigerant that flows out from the oil hole 20, but the amount that flows out from the oil hole 20 becomes approximately constant once the liquid level and the oil hole diameter are determined. Therefore, when the refrigeration load is large, the wetness of the refrigerant sucked into the compressor decreases, and when the refrigeration load is small, the wetness increases. In this embodiment, the compressor sucks refrigerant in a wet state, but even if the compressor inlet is wet, the refrigerant becomes superheated at the cylinder inlet because it is considerably heated internally by the heat generated by the motor.

Therefore, in consideration of this point, the amount of liquid returned from the oil hole 20 is determined so that the compressor is sufficiently safe for liquid compression at the time of the minimum refrigeration load when the wetness of the refrigerant sucked into the compressor is maximum. That's fine.

As explained above, regardless of the refrigeration load, the expansion mechanism of the present invention allows the evaporator to always be used with zero superheat.

Next, another embodiment will be described using FIGS. 3 and 4.

In the figure, the same reference numerals as in FIGS. 1 and 2 indicate the same or equally sized parts.

If the compressor 1 does not have a safety margin against wet refrigerant suction, heat exchange is performed between the compressor suction side and the high pressure side line (in this example, the condenser outlet) as shown in Figure 3. A container 22 is provided to bring the compressor into a superheated state at the suction position of the compressor.

Further, as shown in FIG. 4, a heat exchanger 23 is provided at the bottom of the accumulator, and a high-pressure side line is led here to heat the liquid in the accumulator.

In this case, in the balanced state, the amount of liquid returning from the evaporator 3 is equal to the sum of the amount flowing out from the oil hole 20 of the U-vibe and the amount of evaporation due to heating of the heat exchanger 23, so the amount of liquid returning from the oil hole is It can be suppressed slightly. As explained above, according to the present invention, the opening degree of the expansion valve (needle valve) is controlled using a float so as to keep the liquid level in the accumulator constant, so that the opening of the expansion valve (needle valve) is controlled at the outlet of the evaporator regardless of the refrigeration load. The degree of superheat can be maintained at 0, and therefore the superheat area of the evaporator, which conventionally occupied a large area, is eliminated, making it possible to significantly downsize the evaporator.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a refrigeration cycle using the expansion device of the present invention, FIG. 2 is a sectional view of an accumulator having a float-operated expansion device of the present invention, and FIGS. 3 and 4 are diagrams of the expansion device of the present invention. A system diagram of another refrigeration cycle using

Claims (1)

[Claims] 1. In an accumulator in a refrigeration cycle consisting of a compressor, a condenser, an evaporator, an expansion device, etc., there is a float inside the accumulator that operates in response to changes in the liquid level within the accumulator, and a float that operates in conjunction with the float. a needle valve, the inlet side of the needle valve is connected to a refrigerant pipe on the outlet side of the condenser, and the outlet side of the needle valve is connected to a refrigerant pipe on the inlet side of the evaporator. Accumulator with an expansion device.