JPH03233269A - Coolant concentration sensor for compressor - Google Patents

Abstract

PURPOSE:To provide a simple and small-sized structure and reduce a cost of the structure by a method wherein one end of an electrical conductive wire having the same material as that of one side of a thermocouple is welded, one end of two electrode plates and the other end of the electrical conductor wire are pulled out of a compressor case independently. CONSTITUTION:A thermocouple 16 is comprised of one of two copper plates constituting a mixing ratio sensor 10, a conductive wire 15 having one end welded to a surface of the one copper plate, i.e., a constantan wire. The other end of the constantan wire is pulled out of the compressor case 1. The other electrode plate 11 is commonly used in the mixing ratio sensor 10 and the thermocouple 16 and further integrally formed to each other. Thus, as compared with the case in which a coolant-oil mixing ratio sensor 10 and the thermocouple 16 are separated from each other, it becomes possible to make a simple and small-sized structure. Only three electrical lead wires are satisfactory, so that the sensor may easily be pulled out of the case 1, an electrical wiring around a sensor supporting mechanism and in electrical circuit is facilitated and a cost of the sensor can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Objective of the Invention 1 (Field of Industrial Application) The present invention is useful for detecting the concentration of refrigerant (mixing ratio of refrigerant and oil) contained in the lubricating oil of a compressor. This invention relates to a refrigerant concentration detector that can also detect oil temperature.

(Prior Art) Conventionally, as a refrigerant concentration measuring device for measuring the concentration of refrigerant (mixing ratio of refrigerant and oil) contained in refrigerating machine oil with a pressure of a81,
There is one disclosed in Utility Model Application Publication No. 123574/1983.

Figure 6 shows the outline of the gauging a of the refrigerator.
A sensor C consisting of two opposing electrode plates and a wire mesh d for electromagnetic shielding are placed in an oil reservoir inside the sensor C, and are connected to a measuring instrument g by a wire f passing through an insulating material e. , a high frequency voltage is applied to sensor C to measure the capacitance between the electrode plates.

The measurement principle is that, as shown in Figure 7, there is a difference between the refrigerant concentration in the refrigerant oil and its relative dielectric constant. ) has an almost proportional relationship up to a high concentration (95%), and furthermore, there is a proportional relationship between the refrigerator oil temperature and the refrigerant temperature in the oil within the shaded range in Figure 8. It is based on the fact that the following holds true.

In the case of a refrigerator, the refrigerant concentration in the oil reservoir is 10-15% at an oil temperature of 100°C, and 30-4% even at 50°C.
The focus is on the fact that it rarely exceeds 0%.

Under this assumption, since there is a proportional relationship between the refrigerant concentration and the dielectric constant within the operating temperature range of the refrigerator, it is possible to measure the capacitance of the mixture of oil and refrigerant in the oil reservoir. By doing so, the refrigerant concentration in the refrigerating machine oil can be detected.

According to this refrigerant concentration measuring device, the refrigerant concentration can be easily detected electrically, which has the advantage of being useful for predicting abnormalities in refrigerators, preventing failures, and the like.

(Problem to be solved by the invention) However, when it is desired to precisely measure the mixture ratio of refrigerant and oil in the compressor from changes in capacitance, the oil temperature in the compressor is also measured at the same time, and the mixture ratio is It is desirable to provide temperature compensation for the sensor. This is because even if the oil used has a small effect on the relative permittivity due to temperature changes, the effect of temperature changes may be greater on refrigerants such as R-22.

Therefore, as shown in Fig. 2, inside the case 1 of the compressor,
In addition to the refrigerant/oil mixture ratio sensor 10, it is conceivable to provide a thermocouple 16 as a temperature sensor separately and independently. The number of sensor output terminals is 4.

The present invention was made in consideration of the above circumstances, and is capable of detecting the oil temperature as well as the refrigerant concentration contained in the lubricating oil of the compressor, and the number of sensor output terminals from the compressor case is 3#i.
An object of the present invention is to provide a refrigerant concentration detector for a compressor that requires only a small child.

[Structure of the Invention (Means for Solving the Problems) The refrigerant concentration detector for a pressure Wire machine according to the present invention consists of two sheets made of the same material as one of the two types of metals that can constitute the thermocouple. A capacitance type refrigerant/oil mixture ratio sensor is constructed by arranging electrode plates facing each other, and one end of a conductive wire made of the same material as the other of the thermocouple is welded to the surface of one electrode plate of the sensor,
One end of the two electrode plates and the other end of the conductive wire are electrically drawn out from the case of the pressure 111 machine independently.

(Function) For example, if we consider a thermocouple made of copper and constantan, and if we construct the electrode plate using copper, which is the same material as one of the thermocouples, then the two opposing copper plates will form a capacitive type. The refrigerant/oil mixture ratio sensor is configured, and each is electrically drawn out of the compressor case.

On the other hand, a thermocouple is composed of one of the two copper plates that make up the mixing ratio sensor, and a conductive wire, that is, a constantan wire, whose one end is welded to the surface of the one copper plate, and the other end of the constantan wire is also welded to the surface of the copper plate. Electrically pulled out of the compressor case.

Since one electrode plate is shared by the mixture ratio sensor and thermocouple and is integrated, the structure is simpler than when the refrigerant/oil mixture ratio sensor and thermocouple are separated.

Miniaturization can be achieved. In addition, since only three electrical lead wires are required, it is easy to draw them out of the case, and the wiring around the sensor support structure and electrical circuits is also easy, reducing costs. I can do it.

In addition, it is possible to detect not only the refrigerant concentration contained in the lubricating oil of the compressor, but also the oil temperature at that time, so the characteristics of the refrigerant/oil mixture ratio sensor can be corrected according to the oil temperature to accurately determine the refrigerant/oil temperature. Suitable for determining the mixing ratio.

(Example) Hereinafter, the present invention will be explained based on illustrated embodiments.

In Fig. 1, reference numeral 9 denotes a refrigerant concentration detector, which is a capacitance type refrigerant/oil mixture ratio sensor (hereinafter referred to as It consists of a mixing ratio sensor (simply referred to as a mixing ratio sensor) 10 and a thermocouple 16 partially integrated therewith, and is arranged in an oil sump 24 at the bottom of the refrigerator compressor case 1 by suitable supporting means.

The mixture ratio sensor 10 includes electrode plates 11 and 12 made of metal plates.
are supported in parallel by insulating spacers 13, 13, and the whole is shaped as a rectangular hollow frame. The metal material constituting the electrode plates 11 and 12 is selected from the same materials as one of the two metals constituting the thermocouple.

For example, copper is used for a copper/constantan thermocouple, and chromel is used for a chromel/alumel thermocouple.

In this embodiment, the plates 11 and 12 are made of copper plates, and both copper plates are connected at one end with lead wires 14, 14 made of ordinary electrical conductors.

A total of three output terminals 27, 28, 29 pass through the insulating material 30 airtightly provided on the side wall of the compressor case 1, and the lead wires 14, 14 from the electrode plate 11, 12 are
Two of these three output terminals 27°28.29 (
27, 28).

On the other hand, one of the two copper plates (electrode plate 11) constituting the electrode plates 11 and 12 has a conductive conductor made of a metal material that is to form a thermocouple together with the copper plate on the surface of the intermediate part of the copper plate. Wire 15 is welded.

In the case of this embodiment, since the electrode plate 11 is a copper plate, the conductive wire 1
5 consists of a constantan wire, one end of which is connected to the electrode plate 11.
is welded to the middle part of the The other end of the constant wire is connected to the remaining one or two of the three output terminals 27-29'. In this way, the thermocouple 16 is constituted by the electrode plate 11 made of copper and the conductive wire 15 made of constantan.

The refrigerant concentration detector 9 having the above configuration integrates a capacitance type mixing ratio sensor 10 and a thermocouple 16, and the electrode plate 11 functions as an electrode for measuring capacitance and also serves as a thermocouple. It has the advantage that it also acts as a metal conductor on one side of the pair 16. Therefore, only three output terminals (27 to 29) are required for electrically drawing out the compressor case 1. For comparison, FIG. 2 shows a case where the mixture ratio sensor 10 and thermocouple 16 are provided independently, and compared to the case of FIG. One extra 29a is required.

In the above embodiment, one metal of the thermocouple 16 is constantan, and the other metal is welded to a copper plate as the electrode plate 11 constituting the capacitance type mixture ratio sensor 10. was configured. However, the combination is not limited to such a combination. For example, if the metal materials of the electrode plates 11 and 12 are chromel and the thermocouple 16 is alumel,
Thermocouple A can be configured between the electrode plate 11 and the thermocouple 16.

Of course, even if the metal materials of the electrode plates 11, 12 and the thermocouple 16 are reversed, the same thermocouple will be constructed.

When using the above refrigerant concentration detector 9, the electrode plate 11
．． The output of the capacitance type mixing ratio sensor 10 composed of 12 and t'! The fA plate 11 and the output of the thermocouple 16 constituted by a conductive wire 15 are input to a control unit including a microcomputer, for example, an external microcomputer section in an outdoor unit of an air conditioner.

Then, the control unit uses, for example, the capacitance between the electrode plates 11 and 12 as a component of an oscillation circuit, and the thermocouple 1
The output of 6 is used as a component of the measurement bridge circuit to measure the refrigerant concentration in the oil and the oil temperature, and correction calculations are performed based on the measured values, such as correction according to the characteristics shown in Figs. 7 and 8. Perform calculations and calculate the accurate refrigerant/oil mixture ratio.

Next, a specific usage example of the refrigerant concentration detector 9 will be explained.

FIG. 3 shows the refrigeration cycle of a heat pump type air conditioner, which includes a compressor 1a, an indoor heat exchanger 2. Expansion valve6. Outdoor heat exchanger4. It is constructed by sequentially connecting four-way valves 5 with refrigerant piping. The rotation speed of the compression m 1 a is controlled by an inverter device 8 that receives a command from a control unit 7 .

As shown in FIG. 4, the above-mentioned refrigerant concentration detector 9 is provided in the pressure 11R1a, but here it is provided at the bottom of the compressor 1a so that the refrigerant concentration in the oil can be accurately measured. The compressor f11a consists of a motor 20 and a compressor element 25, and rotates a shaft 23 to operate the compressor element 25 provided at the lower part of the motor section 20 to compress the refrigerant. When compressing this refrigerant, the sliding parts come into metal contact, so lubricating oil from the oil reservoir 24 is sucked in through the suction port 26 to supply oil to the sliding parts to improve lubrication characteristics.

The control unit Y door receives an input signal from the refrigerant concentration detector 9.
Inverter device 8. Indoor fan 3. Expansion valve6. It is configured to control the outdoor fan 4a. That is, the control unit 7 measures the refrigerant concentration in the oil from the capacitance value between the electrodes 11 and 12, which is the output of the mixture ratio sensor 10, and further detects this measured value from the output of the thermocouple 16. Correct according to the oil temperature and find the refrigerant concentration in the oil.

Then, depending on the determined refrigerant concentration, the inverter device 8 indoor fan 3. Expansion valve6. Controls the outdoor fan 4a.

Next, the operation of the air conditioner will be explained using the flowchart shown in FIG.

First, to explain the operation at the time of starting heating operation, the power is turned on in step 101, and when the control unit 7 receives a heating operation start command from the cooling/warming switch by a remote control (not shown), etc., step 102 The control unit 7 then switches the four-way valve 5 to the heating cycle side and proceeds to step 103, where the amount of refrigerant in the oil in the compressor is locked based on the output of the refrigerant concentration detector 9 provided in the compressor 1a. Determine whether there is an abnormal condition that could cause galling.

If it is determined that there is no abnormality here, step 10
6, a normal starting operation is performed, and then the process proceeds to step 107. On the other hand, if it is determined that there is an abnormality, the process proceeds to step 104, where the pressure avl is increased to reduce the load on the compressor 1a compared to the normal starting operation. The starting rotational speed is lowered, the process proceeds to step 105, the throttle amount of the expansion valve 6 is increased, and the process proceeds to step 107.

In step 107, the control unit 7 determines whether the starting operation has been completed, and the process proceeds to step 108.

Next, the operation operation after the start-up operation is completed will be explained.

In step 108, during operation after the start-up operation is completed, the control unit 7 determines from the output of the refrigerant concentration detector 9 whether the amount of refrigerant in the oil in the compressor la is in an abnormal state that may cause locking or galling. .

Here, if it is determined that there is no abnormality, the process proceeds to step 112, where normal heating operation is performed, the pressure Ifiilla is controlled by the inverter device 8, the refrigerant in the refrigeration cycle is circulated, and first, compression @ 1 a is performed. The compressed high-temperature, high-pressure refrigerant gas discharged from the indoor heat exchanger 2 gives heat to indoor air and liquefies it.

Before the liquefied refrigerant is sent to the outdoor heat exchanger 4 through the expansion valve 6, its pressure is lowered to a state where it easily evaporates, and its temperature is lowered.

Then, the liquid refrigerant that has passed through the expansion valve 6 is transferred to the outdoor heat exchanger 4.
is sent to the surrounding air, where it absorbs heat from the surrounding air and evaporates. The refrigerant gas vaporized in the outdoor heat exchanger 4 is sucked into the pressure m1lla. The refrigerant gas sucked into the compressor W1a is compressed within the cylinder, and is discharged after increasing its pressure and temperature.

This operation is repeated to perform heating operation, and the process proceeds to step 112, where the control unit 7 determines whether or not the operation has ended.If the control unit 7 determines that the operation has ended, the power is turned off and the operation is ended. Judging step 10
Return to 8.

On the other hand, if it is determined in step 108 that there is an abnormality, the process proceeds to step 109, and the compression 1! In order to reduce the load on l 1 a, the rotation speed of the compressor is lowered, and step 110
Proceed to step 111 to increase the throttle amount of the expansion valve 6.
Step 108 increases the amount of air blown by the indoor fan 3 installed in the indoor heat exchanger 2, lowers the temperature of the refrigerant in the indoor heat exchanger 2, and lowers the discharge pressure. While there is an abnormality in the oil of step 109. Repeat step 110.

According to this configuration, the refrigerant concentration detector 9 is installed in the oil of the pressurizer.
The reliability of the refrigerant cycle device can be improved by directly detecting and controlling the amount of refrigerant mixed into the lubricating oil in the compressor.

[Effects of the Invention] As described above, the present invention has two electrodes, one of which is shared and integrated with the refrigerant/oil mixture ratio sensor and the thermocouple.
Compared to the case where the refrigerant/oil mixture ratio sensor and the thermocouple are separated, the structure can be simplified and downsized. Also, since the number of electrical lead wires is reduced from four to three,
Easy to pull out of the case, sensor support structure,
Wiring around the electrical circuit becomes easier, and costs can be reduced.

In addition, it is possible to detect not only the refrigerant concentration contained in the lubricating oil of the compressor, but also the oil temperature at that time, so the characteristics of the refrigerant/oil mixture ratio sensor can be corrected according to the oil temperature to accurately determine the refrigerant/oil temperature. Suitable for determining the mixing ratio.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a refrigerant concentration detector according to an embodiment of the present invention, Fig. 2 is a block diagram of a case where a refrigerant/oil mixture ratio sensor and a thermocouple are provided separately, and Figs. 3 to 5 The figure shows an example of application of the refrigerant concentration detector of the present invention to an air conditioner.
Figure 3 is a schematic diagram of the air conditioner, and Figure 4 is the pressure! a A partial sectional view showing the position of the refrigerant concentration detector inside the machine; Fig. 5 is a flowchart showing the operation of the control unit; Fig. 6
The figure is a schematic diagram of a conventional refrigerant concentration measuring device, Figure 7 is a diagram showing the relationship between the refrigerant concentration in oil and the dielectric constant, and Figure 8 is a diagram showing the relationship between oil temperature and refrigerant concentration in oil. FIG. In the figure, 1 is the compressor case, 9 is the refrigerant concentration detector, and 10 is the compressor case.
11.12 is a refrigerant/oil mixture ratio sensor, 11.12 is an electrode plate, 13 is a spacer, 14 is a lead wire, 15 is a conductive wire that constitutes a thermocouple, 16 is a thermocouple, 24 is an oil sump, 27, 28, and 29 are Shows the output terminal.

Claims (1)

[Claims] 1. Construct a capacitance type refrigerant/oil mixture ratio sensor by arranging two electrode plates made of the same material as one of the two metals that can constitute the thermocouple, and one electrode of the sensor. One end of a conductive wire made of the same material as the other thermocouple is welded to the surface of the plate, and one end of the two electrode plates and the other end of the conductive wire are electrically connected to the outside of the compressor case independently. A refrigerant concentration detector for a compressor, which is characterized by being pulled out.