JPH01259238A - Oil content measuring instrument for refrigerating cycle - Google Patents

Abstract

PURPOSE:To easily measure the content of oil in a refrigerant by interposing a sampling container in a line which makes a bypass connection between a condenser downstream side and a compressor low-pressure side. CONSTITUTION:When the oil content is measured, an opening/closing valve 22a is opened in stationary operation to put a liquid refrigerant in the sampling container 20 by a prescribed amount, and its volume is read. Then when an opening/closing valve 22 is opened, the liquid refrigerant in the sampling container 20 boils and vaporizes at a constant speed with the suctional force of the low pressure side of a compressor 12, so that only the gaseous refrigerant is sucked to the compressor 12 through a constant-flow-rate valve 23. When the temperature of the liquid refrigerant in the sampling container 20 drops, a temperature sensor 28 detects that and turns on a temperature controller 27 to accelerate the vaporization of the liquid refrigerant. When the vaporization is finished, the opening/closing valve 22b is closed, the level of the oil remaining in the sampling container 20 is read on a scale, and the volumetric circulation rate of the oil to the refrigerant is found from the volume of the oil and the volume of the liquid refrigerant which flows in the container first.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a refrigeration cycle oil content measurement device that measures the oil content in a refrigerant circulating in a refrigeration cycle.

[Prior Art] Conventionally, as means for detecting refrigerant leakage or refrigerant shortage during 1 day of refrigeration in refrigerators, heat pumps, etc., there are, for example,
As disclosed in Japanese Unexamined Patent Publication No. 60-17672, the degree of superheat of the gas refrigerant sucked into the compressor is detected, and if the value is higher than a predetermined value, an alarm is issued and the refrigerant is stopped. There is something that lets you know when something is missing.

By the way, when there is a shortage of refrigerant in the refrigeration cycle due to leakage, it is necessary not only to replenish the refrigerant for the shortage, but also to replenish oil to appropriately adjust the oil content of the refrigerant.

The purpose of the oil contained in the refrigerant is to prevent seizure of the compressor, and it must have a fit (oil content) that reduces the required amount, taking into account the performance deterioration of heat exchangers such as condensers. Must be.

Conventionally, as a means for determining the oil content in the refrigerant, as shown in FIG. Then, take a predetermined amount of liquid refrigerant, take it outside, measure the total weight of the liquid refrigerant, boil the liquid refrigerant, measure the remaining oil, and record it with the total weight of the refrigerant. There is a method that calculates the oil content in the refrigerant from the remaining amount of oil.

[Problems to be Solved by the Invention] However, the conventional oil content measurement of the refrigeration cycle described above has the following problems.

(1) Since the liquid refrigerant is sampled externally and measured, it takes time to measure the liquid refrigerant, and requires appropriate measurement equipment, which poses a problem in terms of cost.

(2) Obtaining highly reliable measurement results requires skill, and measurement results vary from worker to worker.

(3) After collecting the liquid refrigerant, it is necessary to replenish the refrigerant and oil, making it difficult to smoothly transition to the next freezing cycle operation.

(4) If several removable sampling containers are used during a cycle, the internal volume of the cycle increases and there is a problem that accurate oil content cannot be measured.

(5) Also, as shown in Fig. 5, mix the part 5a of the density layer 5 on the liquid refrigerant side of the line 4 (some methods calculate the oil content from the refrigerant density, If the mixing ratio of oil and oil is unknown, the oil properties are unknown, or an unstable mixed refrigerant (oil mixed in the refrigerant) is used, calculate the oil content from the superposition ratio. [Object of the Invention] The present invention was made in view of the above circumstances, and it is possible to control the oil content in a refrigerant using simple equipment, regardless of the mixing ratio of the mixed refrigerant and the properties of the oil. It is easy to measure n1, and anyone can easily obtain a highly reliable word measurement.
It is an object of the present invention to provide an oil content measuring device for a refrigeration cycle which is capable of measuring oil content in a refrigeration cycle and is economical since there is no need to replenish the collected refrigerant.

[Means and effects for solving the problem] The refrigeration cycle oil content meter 11111 device according to the present invention has the following features:
A sampling container is installed in the line that bypasses the downstream side of the Ndenza and the low pressure side of the Ndenza. First, during refrigerant cycle operation, turn on the on-off valve on the upstream side of the collection container. is closed, and the volume of liquid refrigerant stored in this collection container is calculated.

Next, when the on-off valve is closed and the on-off valve on the downstream side of the collection container is opened, this collection container becomes under negative pressure, and the liquid refrigerant boils and vaporizes while flowing through the on-off valve and into the low-pressure side of the compressor. is attracted to. After the liquid refrigerant is completely vaporized, the on-off valve is closed, and the volume of oil remaining in the collection container is measured.

Thereafter, the content of oil in the refrigerant is determined from the volume of the liquid refrigerant measured first and the volume of the oil.

[Embodiment 1 of the invention Hereinafter, the present invention will be described in detail with reference to the drawings.

Figures 1 to 3 show an embodiment of the present invention, Figure 1 is a schematic diagram of a refrigeration cycle, Figure 2 is a circuit diagram of a temperature adjustment device,
FIG. 3 is a characteristic diagram of the temperature sensor.

(Configuration) The number 11 in the figure is a refrigerating tank, and the =1 compressor 12 installed in this refrigerating cycle 11 is connected to the engine 1.
3 via an electromagnetic clutch (not shown) so as to be able to freely approach and separate.

Further, in the refrigeration cycle 11, a condenser 14 and a liquid receiver 15 are connected from the high pressure side to the low pressure side of the brezzar 12.
, an on-off valve 16, an inflation valve 17, and a vaporizer 18 are connected in order through a line 19.

Reference numeral 20 denotes a collection container, and the upper part of the collection container 20 is connected to a bypass line 21 that connects the liquid line 19a on the downstream side of the liquid receiver 15 and the gas line 19b on the low pressure side of the complete tree 12 by bypass. It is connected to the.

Furthermore, on-off valves 22a and 22b are interposed on both sides of the bypass line 21, sandwiching the collection container 20 therebetween.

Further, an electrolytic liquid amount valve 23 is interposed in the bypass line 21 on the downstream side of the on-off valve 22b.

This electrolytic liquid amount valve 23 controls the boiling temperature within the collection container 20.
- At times, this is to prevent the degree of foaming of the mixed refrigerant and to prevent oil from flowing out through the electro-hydraulic quantity valve 23.

Further, a pressure gauge 24 for measuring the internal pressure of the collection container 20 is provided on the top of the collection container 20.

Further, the bottom portion 20a of the collection container 20 is formed in a hollow shape, and its tip is connected via an on-off valve 25 to the bypass line 21 on the side communicating with the gas line 19b.

The collection container 20 shown in J3 in the figure is a transparent container, and the bottom part 20a is engraved with a scale that can measure the amount of h1 in units of 1/10 cc, for example, and from there upward there are scales in 1 cc units. is engraved.

In addition, this collection container 20 must be assembled in a vacuum-dried state.
It is being taken.

Furthermore, a heater 26 is attached to the bottom 20a of the collection container 20, and this heater 26 is connected to a temperature adjustment device 27. Furthermore, the bottom portion 20 of the collection container 20
A temperature sensor 28 for detecting the temperature of the liquid refrigerant stored in the collection container 20 is attached to the temperature sensor 28, and the temperature sensor 28 is connected to the temperature adjustment device 27.

The humidity sensor 28 uses a thermistor whose resistance value R changes as the temperature decreases, as shown in FIG. let

FIG. 2 is a specific circuit diagram of the temperature adjustment device 27, in which resistors R1 and R are connected to the non-inverting input terminal of the comparator OP1.
2 is connected to a constant voltage element V, and this resistor R1
, R2, the temperature sensor 28 is connected between them.

Further, the inverting input terminal of the comparator OPI is connected to the constant voltage voltage V
A voltage dividing connection is made between a resistor R3 connected to the resistor R3 and a variable resistor R4.

Roughly speaking, the output terminal of this comparator OP1 is the transistor Q.
It is connected to the base of 1. This 1~ransistor Q1
The collector side of is connected to the constant voltage element (2), and the emitter side is connected to the excitation coil 29a of the relay 29.

Furthermore, one of the two relay contacts 29b of this relay is
It is connected to the power supply VCC via the power switch SW1, and the other end is connected to the heater 26.

(for production) Next, the operation of the embodiment with the above configuration will be explained.

(During steady operation) When the engine 13 is operated, the compressor 12 is driven via an electromagnetic clutch (not shown), and the refrigeration cycle 11 is driven.
Refrigerant circulates inside.

During this time, the high temperature and high pressure gas refrigerant compressed by the compressor 12 releases heat in the condenser 14, is liquefied, and is stored in the liquid receiver 15.

Thereafter, the liquid refrigerant flows into the evaporator 18 from the fat expansion valve 17 via the on-off valve 16 disposed in the liquid line 19a, and absorbs heat and vaporizes in the evaporator 18, becoming a low-temperature, low-pressure gas refrigerant and forming a gas line. It passes through 19b and is sucked into the low pressure side of the compressor 12.

Note that the refrigerant contains a predetermined amount of oil, which circulates in the refrigeration power cycle 11 together with the refrigerant to lubricate the compressor 12. Also, the opening/closing valve 22a of the bypass line 21.

Both valves 22b and 25 are in a closed state.

(Measurement of oil content rate) On the other hand, when measuring the oil content rate, first open the on-off valve 22a while maintaining the steady operation. Then, collection container 2
A liquid refrigerant flows into the sampling container 20, and the liquid refrigerant flowing into the collection container 20 is read on a scale whose volume is calibrated in advance.

When a predetermined amount of liquid refrigerant is stored in the collection container 20, the on-off valve 22a is closed and its volume is read.

Next, when the on-off valve 22b is opened, the pressure inside the collection container 20 is reduced by the suction force on the low pressure side of the compressor 12.
The liquid refrigerant stored in this collection container 20 is boiled and vaporized at a constant rate, and only the refrigerant is guided to the gas line 19b through the constant flow valve 23 (the liquid refrigerant passes through the electrostatic liquid flow valve 23). It is attracted to the above-mentioned complete tree 12.

On the other hand, when the humidity of the liquid refrigerant in the collection container 20 drops below the set temperature (temperature To in FIG. 3) due to latent heat during vaporization,
The temperature adjustment device 27 is turned on by the output signal of the temperature sensor 28, the heater 26 is energized, and the liquid refrigerant in the collection container 20 is heated. As a result, the vaporization of the liquid refrigerant in the collection container 20 is promoted again.

Then, the liquid refrigerant in the collection container 20 is at the set temperature T.
When the temperature exceeds 0, the temperature adjusting device 27 detects this based on the output j signal of the temperature sensor 28, and cuts off the power supply to the heater 26.

Note that the control dynamics of this temperature adjustment device 27 will be described later.

By the way, the electric liquid amount valve 23 is for adjusting the boiling speed of the liquid refrigerant so that the oil in the collection container 20 completely remains.

When the boiling phenomenon in the collection container 20 approaches the end, the on-off valve 16 installed in the liquid wine 19a is closed, and the evaporator 18, the gas line 19b, the collection container 20, and the bypass line 21 are closed. All of the gas refrigerant in the refrigerant is sucked in by the combrella pump 12 and stored in the refrigerant 14 and receiver 15.

Then, after all of the liquid refrigerant in the collection container 20 has been vaporized, the on-off valve 2'2b is closed.

Next, the level of oil remaining in the collection container 20 is read from the scale, and the volume of this oil is determined.
The volumetric circulation rate of the oil to the refrigerant is calculated from the volume of the liquid refrigerant (containing oil) that first flows in.

This volumetric circulation rate is determined by the thermometer installed in the collection container 20 (
Alternatively, the temperature at the time the liquid refrigerant is stored and the temperature of the remaining oil are measured from the output signal of the temperature sensor 28, and each is calculated by converting them using a specific gravity table.

After determining the volume circulation rate to a predetermined value, the on-off valve 22
a, 25, the collection container 20C is washed with the liquid refrigerant flowing in from the liquid line 19a, and the residual oil is dissolved in this liquid refrigerant, and the bottom part 20 of the collection container 20 is cleaned.
The gas line 19 is connected from the tip of a through the on-off valve 25.
It flows out to the b side.

Note that a compressor 12 is installed downstream of this on-off valve 25.
In order to avoid liquid compression, an unillustrated throttling mechanism such as a capillary cove is installed.

After the cleaning of the collection container 20 is completed, the on-off valve 22a is closed, and when the inside of the collection container 20 reaches the pressure of the gas line 19b while checking the indicated value of the pressure gauge 24, the on-off valve 25 is closed. , prepare for the next set of measurements.

Note that the on-off valves 22a, 22b, and 25.16 may be solenoid valves so that they can be automatically controlled.

Further, the amount stored in the collection container 20 may be read remotely using an optical sensor or the like.

(Operation of temperature adjustment device 27) Further, the temperature adjustment device 27 operates as follows.

First, turn on the power switch 1.

Further, a temperature sensor 28 detects the temperature of the liquid refrigerant stored in the collection container 20. This temperature adjustment device 27
As shown in FIG. 3, a thermistor whose resistance value changes depending on the temperature is used.

When the temperature of the liquid refrigerant stored in the collection container 20 is below the set temperature TO, the drought sensor 4 (thermistor) 28
The resistance value R becomes larger than the set value R'0, and the variable resistance R
Reference voltage J input to the inverting input terminal of comparator OP1 set by
It is input to the non-inverting input terminal of 1.

Then, 11 signals are output from the output terminal of the comparator OP1 to the base of the transistor Q1, turning the transistor Q1 ON and exciting the excitation coil 29a of the relay 29.

As a result, the relay contact 29b of this relay 29 becomes ONI.
A current is applied to the heater 26 from the power supply Vcc, and the liquid refrigerant in the collection container 20 is heated.

Then, as the temperature of the liquid refrigerant in the collection container 20 gradually rises, the resistance value of the temperature sensor 28 gradually decreases, and when the temperature of the liquid refrigerant exceeds the set value TO,
The reference voltage input to the inverting input terminal is higher than the voltage input to the non-inverting input terminal of the comparator OP1,
An L signal is output from the output terminal, and the transistor Q
1 is 0FFL, the relay 29 is 0FFL, and the power supply to the heater 26 from the power supply VCC is cut off.

In this way, the liquid refrigerant that is being boiled and vaporized in the collection container 20 is maintained at a substantially constant temperature, and the latent heat taken away by the vaporization of the liquid refrigerant is compensated for.

Note that this temperature adjustment device 27 may be a proportional temperature control method.

[Effects of the Invention] As explained above, according to the present invention, collection containers are interposed in the line that bypass connects the downstream side of the condenser and the low pressure side of the compressor. Since on-off valves are installed on the upstream and downstream sides of the container, opening the on-off valve on the upstream side allows a predetermined amount of liquid refrigerant containing reoil to be collected into the collection container. Also, by opening the on-off valve on the upstream side and the on-off valve on the downstream side, the liquid refrigerant stored in the collection container is prevented from boiling and vaporized, and only the oil remains inside the container. can be done.

As a result, the oil content in the refrigerant can be easily measured with simple equipment, regardless of the mixture ratio of the refrigerant and the properties of the oil. Moreover, anyone can easily measure H1 with high reliability. Not only can you get results, you can also measure the oil content while the refrigeration cycle is running, and what's more, the sampled refrigerant is returned to the refrigeration cycle, so you don't have to close the sampling valve as before. It has excellent effects such as being economical and not requiring new supplies.

[Brief explanation of the drawing]

Figures 1 to 3 show an embodiment of the present invention. Figure 1 is an external circuit diagram of a refrigeration unit, Figure 2 is a circuit diagram of a temperature adjustment device, and Figure 3 is a characteristic diagram of a humidity sensor. , FIG. 4, and FIG. 5 are schematic diagrams showing conventional oil content measuring means. 12... Compressor, 14... Capacitor, 20
... Collection container, 21 ... Line, 22a, 22b.
...Open = 16- Valve closed. Figure 4 Figure 5

Claims (1)

[Claims] A sampling container is interposed in a line that bypass-connects the downstream side of the condenser and the low pressure side of the compressor, and on-off valves are interposed on the upstream and downstream sides of the line that sandwich the sampling container. A device for measuring oil content in refrigeration cycles.