JPH02140557A - Compressor protecting device for refrigerating cycle - Google Patents

Abstract

PURPOSE:To so protect a compressor as not to operate in a state of insufficient lubrication by detecting the circulating rate of lubricating oil according to the change of light passing the oil, and controlling its varying amount in an allowable range. CONSTITUTION:In a refrigerating cycle Rc, suitable amounts of both refrigerant and lubricating oil are sealed. As the oil, naphthene oil, alkyl benzene oil, etc. containing a large quantity of unsaturated group such as aroma group, etc. of ultraviolet ray phosphor substance is employed. The flow rate of the circulating oil in the cycle Rc is detected by an oil flowrate sensor S by utilizing the fact that the oil contains the phosphor substance, and a compressor 10 is protected by stopping it when the flow rate is insufficient. Thus, the compressor 10 is normally operated while protecting it against its lock, etc. due to insufficient lubrication and suitably maintaining its thermal exchanging rate in the cycle Rc only by sealing necessary sufficient oil in the cycle Rc without employing excess components.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a refrigeration cycle, and particularly to a compressor protection device suitable for protecting a compressor employed in the refrigeration cycle.

(Prior art) Conventionally, for example, near conditioners for vehicles have been required to be smaller and lighter, so the compressor used in the refrigeration cycle of the near conditioner has also been required to be smaller and lighter. . Therefore, in order to meet this demand, a type of compressor without a built-in oil chamber is adopted, and the compressor is lubricated by circulating lubricating oil together with the refrigerant during the refrigeration cycle. This is the current situation.

(Problem to be Solved by the Invention) However, in such a refrigeration cycle, there is a risk that the amount of lubricating oil returned to the compressor will decrease due to lubricating oil leakage or refrigerant leakage, resulting in insufficient lubrication. Since there is
A larger amount of lubricating oil than necessary is prefilled in the refrigeration cycle. Therefore, even if the compressor can be properly lubricated, the heat exchange efficiency of the refrigeration cycle deteriorates.

To deal with this, it is possible to adopt an oil separator to collect lubricating oil and return it to the compressor, as shown in Japanese Patent Application Laid-Open No. 54-112052 or Japanese Utility Model Application No. 62-80164. However, vehicle air conditioners have problems such as high costs and complicated refrigeration cycles.

Therefore, in order to cope with the above problems, the present invention enables the compressor to operate in a state of insufficient lubrication in the refrigeration cycle without employing redundant parts or filling in an unnecessarily large amount of lubricating oil. To provide a compressor protection device that can protect the compressor from damage.

(Means for solving the problem) In solving the problem, the structural features of the present invention are as follows:
As illustrated in FIG. 1, in a refrigeration cycle 1 in which a refrigerant and a lubricating oil are sealed and the refrigerant is circulated together with the lubricating oil according to the selective operation of the compression means 1a, the circulation rate of the lubricating oil is A detection means 2 for detecting the amount of change in light passing through the lubricating oil, and a control means 3 for controlling the compression means 1a to protect the compression means 1a when the detected amount of change is out of an allowable range. be.

(Function) By configuring the present invention in this way, when the refrigerating cycle 1 is circulating refrigerant and lubricating oil under the operation of the compression means 1a, the amount of change detected by the light of the detection means 2 is within the above-mentioned allowable range. If it goes out of the range, the control means 3 starts the compression means 1a.
control to protect.

(Effect) In this way, when it is determined that the detected amount of change deviates from the allowable range and the amount of lubricating oil is insufficient, the compression means 1a is immediately protected, so there is no need to use surplus parts. In addition, it is possible to properly operate the compression means 1a while maintaining an appropriate heat exchange rate and protecting the compression means 1a from lock failures due to insufficient lubrication without enclosing more lubricating oil than necessary.

(Example) Hereinafter, the first example of the present invention will be explained with reference to the drawings. Fig. 2 shows the refrigeration cycle Rc of the vehicle near conditioner
This refrigeration cycle Rc is filled with appropriate amounts of refrigerant and lubricating oil. In such a case, as the lubricating oil, an ultraviolet fluorescent substance such as naphthenic oil, alkylbenzene oil, etc. containing a large amount of unsaturated groups such as aromatic groups is employed. The refrigeration cycle Rc is equipped with a small and lightweight compressor 10, and this compressor 10 is operated by selective engagement of an electromagnetic clutch 20.
It operates by receiving power transmitted from the engine of the vehicle through the pulley 30, sucks the refrigerant in the pipe P1 together with lubricating oil, compresses the sucked refrigerant while receiving the lubricating action, and transfers this compressed refrigerant together with the lubricating oil to the pipe P2. Exhale inside. Note that the electromagnetic clutch 20 is engaged by selective excitation of its electromagnetic coil 20a.

The condenser 40 receives the compressed refrigerant together with lubricating oil from the pipe P2, condenses the compressed refrigerant under the heat dissipation effect of a cooling fan (not shown), and applies the condensed refrigerant together with the lubricating oil to the pipe P3. The gas-liquid separator 50 receives the condensed refrigerant and lubricating oil from the pipe P3, separates the condensed refrigerant into a gas phase component and a liquid phase component, and uses this liquid phase component as a refrigerant together with the lubricating oil in the pipe P4 of the present invention. It is applied to the expansion valve 60 through the oil flow rate sensor S, which constitutes the main part, and the piping P5. The expansion valve 60 expands the refrigerant from the pipe P5 according to the temperature detection result of the refrigerant in the pipe P by the temperature detection element 60a, and applies the refrigerant as a low-temperature, low-pressure refrigerant to the evaporator 70 through the pipe P6 together with lubricating oil. . The evaporator 70 cools the airflow from the blower 70a to be blown into the passenger compartment of the vehicle according to the evaporation effect of the inflowing refrigerant, and applies the refrigerant together with lubricating oil into the pipe Pl. Note that each of the pipes P1 to P6 is made of aluminum material.

As shown in FIGS. 2 to 4, the oil flow rate sensor S is connected to both piping p4. p, and are coaxially assembled between the two. This oil flow sensor S has a casing 100, and this casing 10o has a cylindrical body 100 made of aluminum material.
a and a lid body 100b. Cylindrical body 10
0a has a through hole 101 bored in the center of its bottom wall,
It is fitted to one end of the pipe P5 by brazing, and the lid 100b is attached to the central boss portion 1 of the cylinder 100a.
02 is fitted and assembled into the open end of the cylindrical body 100a by brazing. The lid body 100b is fitted to one end of the pipe P4 by brazing at a through hole 103 bored in the center thereof, and the inside diameter of the through hole 103 is the same as the inside diameter of the through hole 101. equal.

The glass tube 110 is made of transparent pressure-resistant glass such as quartz glass, and the outer surface of the glass tube 110 is provided with a pair of left and right O-rings 110a, 110b, 110c, and 110d on the inner surface of the hollow part of the casing 100. It is coaxially fitted into the center of the casing 100 so as to be in close contact with each other. In this case, the inner diameter of the glass tube 110 is equal to the inner diameter of each of the through holes 101 and 103 of the casing 100.

The light emitting body 120 has a substantially annular holder 121 made of aluminum material, and the boss portion 121a of the holder 121 is sealed in a through hole portion 104 bored in the radial direction at the center of the peripheral wall of the casing 100. The flange portion 121b is attached to the outer peripheral edge of the through hole portion 104 by brazing. In this case, the end surface of the boss portion 121a of the holder 121 is in close contact with the center of the outer peripheral surface of the glass tube 110 in an arc shape.

Inside the large diameter portion of the stepped hollow hole 121c of the holder 121,
A light source 123 consisting of a hydrogen discharge tube is fitted coaxially through a filter 122, and the light source 123 is connected to the constant voltage power supply 12.
It receives a constant voltage from 0a (see Figure 2) and emits ultraviolet light. The filter 122 receives ultraviolet light from a light source 123 at a predetermined wavelength^. Only the ultraviolet rays of =313±10 (nm) are allowed to enter the hollow portion of the glass tube 110 through the small diameter portion of the stepped hollow hole 121c and the peripheral wall of the glass tube 110.

Note that screws 124a are attached to the flange portion 121b of the holder 121 so that a lid body 124 made of aluminum material seals the large diameter portion of the stepped hollow hole 121c.

124a.

Here, a description will be given of the optical characteristics of the lubricating oil flowing from the pipe P4 to the pipe P through the glass tube 110 in relation to the ultraviolet rays that enter the hollow part of the glass tube 110 from the filter 122. The unsaturated groups in lubricating oil have the characteristic of emitting fluorescence in a scattering manner when exposed to ultraviolet light. Therefore, when we investigated the relationship between the flow rate Q of lubricating oil (that is, the flow rate of unsaturated groups) in the glass tube 110 and its fluorescence intensity I, we found that the Q-I characteristic shown in FIG. It was done. Therefore, the lubricating oil in the glass tube 110 is
In relation to the incident ultraviolet rays, it emits fluorescence in a scattering manner with a fluorescence intensity (2) depending on the flow rate Q of the incident ultraviolet rays.

Note that the portion of the incident ultraviolet light that does not contribute to fluorescence travels straight in the direction of the incident ultraviolet light.

The photoreceptor 130 has a substantially annular holder 131 made of aluminum material, and this holder 131 has a boss portion 131a located at the center of the peripheral wall of the casing 100 with respect to the axis of the through hole portion 104 as shown in FIG. The flange portion 131b is tightly fitted into the through hole portion 105 formed perpendicularly to the radial direction of the hole portion 105, and the flange portion 131b is fixed to the outer peripheral edge portion of the through hole portion 105 by brazing. In this case, the distal end surface of the boss portion 131a of the halter 131 is in close contact with the center of the outer peripheral surface of the glass tube 110 in an arc shape. A photovoltaic cell 132 is fitted coaxially into the large diameter portion of the stepped hollow hole 131c of the holder 131.
2, the lubricating oil in the glass tube 110 is removed from the holder 131.
Fluorescence (350 soil 1
It receives light 〉 having a wavelength of 0 (nm) and generates a light receiving voltage 〉.

In such a case, the light receiving voltage (2) is proportional to the fluorescence intensity (I) of the fluorescence from the lubricating oil. A lid 133 similar to the lid 124 is provided with screws 133a on the flange portion 131b.

133a.

Next, the electric circuit configuration for the electromagnetic clutch 20 will be described with reference to FIG. 2. The operation switch SW is operated to generate an operation signal when operating the near conditioner. The AD converter 200a digitally converts the light receiving voltage V from the photovoltaic cell 132 and generates it as a digital voltage (2). The microcomputer 200b executes the computer program in cooperation with the A-D converter 200a according to the flowchart shown in FIG. .

Performs calculation processing for 200d. However, the computer program is previously stored in the ROM of the microcomputer 200b. In addition, the microcomputer 20
0b is connected to battery B via ignition switch IG.
The controller is supplied with power from the controller SW, enters the operating state, and starts executing a computer program in response to an operation signal from the operation switch SW.

In the first embodiment configured in this manner, when the ignition switch IG is closed, the engine of the vehicle is started and the vehicle is started, and the microcomputer 200b is put into operation. , when the light source 123 emits ultraviolet light in response to a constant voltage from the constant voltage power supply 120a, this ultraviolet light passes through the filter 122 and has a predetermined wavelength λ. As the ultraviolet rays of the glass tube 1
The light passes through the peripheral wall of the glass tube 110 and enters the hollow portion of the glass tube 110. Then, the lubricating oil present in the hollow part of the glass tube 110 receives the co-infrared ultraviolet rays and fluoresces, scatteringly emitting fluorescence at a fluorescence intensity 2 determined based on the Q-I characteristic p.

Next, the photocell 132 emits the fluorescence from the lubricant onto the holder 1.
The light is received through the small diameter part of the stepped hollow part 131c of No. 31, and a light receiving voltage V is generated.

When an operation signal is generated from the operation switch SW, the microcomputer 200b starts executing a computer program at step 300a according to the flowchart of FIG.
A-D converter 200 generated based on the received light voltage from 32
The digital voltage (2) from a is compared with a predetermined voltage Vo.

In the case of brightening, the predetermined voltage Vo corresponds to the predetermined fluorescence intensity Io and is stored in advance in the ROM of the microcomputer 200b. However, as shown in FIG.
0 (for example, 1 kg/h). Moreover, this predetermined flow rate Qo corresponds to the upper limit of the flow rate of lubricating oil at which lubrication of the compressor 1o becomes insufficient.

At such a stage, if V>Vo, the microcomputer 200b selects rYES in step 300b.
In step 300c, an engagement signal necessary for engaging the electromagnetic clutch 20 is generated, and in response to this, the drive circuit 200c excites the electromagnetic coil 20a. Then, the electromagnetic clutch 20 is engaged by the excitation of the electromagnetic coil 20a, transmitting engine power to the compressor 10 and operating it.

The compressor 10 sucks the refrigerant and lubricating oil in the pipe P1, compresses the refrigerant, and discharges the compressed refrigerant together with the lubricating oil into the pipe P2, and the condenser 40 receives the compressed refrigerant and lubricating oil from the pipe P2. The compressed refrigerant is condensed under the heat dissipation action of the cooling fan and applied as a condensed refrigerant into the pipe PS together with lubricating oil.

Next, the gas-liquid separator 50 receives the condensed refrigerant and lubricating oil from the pipe P3, separates the condensed refrigerant into a liquid phase component and a gas phase component, and uses the liquid phase component as a refrigerant together with the lubricating oil to pass through the pipe P4 and the oil flow sensor S. The expansion valve 60 expands the refrigerant as a low-temperature, low-pressure liquid refrigerant and supplies it to the evaporator 70 through the pipe P6 together with lubricating oil according to the detection result of the temperature detection element 60a. Give. Therefore, the evaporator 70 cools the airflow to be blown into the vehicle interior from the blower 70a under the effect of evaporating the inflowing refrigerant, and applies the inflowing refrigerant to the compressor 10 through the pipe P1 together with the inflowing lubricating oil.

In such a case, as determined by V>vO in step 300b, the amount of lubricating oil circulating in the refrigeration cycle Rc is Q>Qo, as is clear from FIG. 5, so that the compressor 10 is sufficiently lubricated. done to. In addition, in the oil flow sensor S, since the axis of the light emitter 120 and the axis of the photoreceptor 130 intersect at right angles, the fluorescence of the lubricating oil among the ultraviolet rays that enter the hollow part of the glass tube body 110 from the filter 122 A portion that does not contribute to the voltage is not received by the photovoltaic cell 132, and as a result, erroneous determination that V>Vo is prevented. Therefore, a situation in which the compressor 10 is operated despite the lack of lubricating oil does not occur.

Further, in the above-mentioned operating state, the refrigeration cycle R
Since the amount of lubricating oil circulating through c has been unnecessarily reduced due to leakage, etc., the determination in step 300b is "N".
O'', the microcomputer 200b generates a lighting signal necessary for lighting the indicator lamp L in step 300d, and extinguishes the engagement signal in step 300e.

Therefore, the drive circuit 200d is connected to the microcomputer 2.
The display lamp L is turned on in response to the lighting signal from 00b. Thereby, it can be visually recognized that the amount of circulating lubricating oil in the refrigeration cycle RC is insufficient. In addition, the drive circuit 200
C demagnetizes the electromagnetic coil 20a when the engagement signal from the microcomputer 200b disappears, and in response to this, the electromagnetic clutch 20 disconnects the compressor 10 from the engine to stop and protect it. Thereby, it is possible to prevent the occurrence of a lock failure due to insufficient lubrication of the compressor 10, which tends to occur due to insufficient amount of circulating lubricating oil in the refrigeration cycle Rc. In such a case, the light emitter 1 as described above
On the premise of preventing the determination that V≦VO based on the fact that the respective axes of the photoreceptor 20 and the photoreceptor 130 are perpendicular to each other, malfunctions of the compressor 10 in the absence of lubricating oil can be prevented.

As explained above, focusing on the fact that the lubricating oil contains an ultraviolet fluorescent substance, the oil flow sensor S detects the flow rate of the circulating lubricating oil in the refrigeration cycle Rc, and when the flow rate is insufficient, the compressor 10 is stopped. As a result, the heat exchange rate in the refrigeration cycle Rc can be properly maintained by simply sealing the necessary and sufficient lubricating oil into the refrigeration cycle Rc, without using any redundant components (for example, an oil separator). At the same time, the compressor 10 can be operated normally while being protected from locking due to insufficient lubrication.

Note that in implementing the present invention, the filter 122 is
Not limited to those that transmit only ultraviolet rays with a wavelength of λo = 313 ± 10 (nm), but those that transmit ultraviolet rays with a wavelength of λ = 100 to 600 (nm) or those with a wavelength of λ = 130 to 65
Any material that allows the photoreceptor 130 to receive fluorescence within the range of 0 (nm) may be used.

Furthermore, in carrying out the present invention, various intersection angles between the light emitter 120 and the light receiver 130 of the oil flow rate sensor S are not limited to right angles, and may be changed as appropriate.

Next, a second embodiment of the present invention will be described with reference to FIGS. 7 to 9. In this second embodiment, the light emitter 120A is the same as the light emitter 120A described in the first embodiment. Unlike the light emitter 120, this light emitter 12OA is adopted in place of the light emitter 120, as shown in FIG.
It is fitted into the casing 100 so as to face the.

In such a case, in the light emitter 120A, the filter 12
2A is fitted in the stepped hollow hole 121C of the holder 121 in place of the filter 122 described in the first embodiment. = 230~400 (n
Only the ultraviolet rays m) are allowed to enter the hollow portion of the glass tube 110 through the small diameter portion of the stepped hollow hole 121c and the peripheral wall of the glass tube 110.

Furthermore, in the refrigeration cycle Rc, a lubricating oil containing a large amount of ultraviolet absorbing substance is sealed together with a refrigerant instead of the lubricating oil containing an ultraviolet fluorescent substance described in the first embodiment. In such a case, there is a difference between the flow rate Q of lubricating oil in the glass tube 110 based on the ultraviolet absorption characteristics of the lubricating oil and the amount T of ultraviolet light transmitted from the light emitter 120A that passes through the lubricating oil and enters the photoreceptor 130. The relationship is specified by the curve m shown in FIG. According to this, it can be seen that as the flow rate Q of lubricating oil increases (or decreases), the transmitted amount T of ultraviolet rays decreases (or increases). Further, the ROM of the microcomputer 200b stores in advance a flowchart modified as shown in FIG. 9 based on the flowchart in FIG. 6 as a modified computer program in place of the computer program in the first embodiment. There is. Note that the photovoltaic cell 132 receives the transmitted ultraviolet rays from the glass tube 110 and generates a light receiving voltage V. Other configurations include the first
This is similar to the example.

In the second embodiment configured as described above, the first
After starting execution of the modified computer program in step 300a (see FIGS. 6 and 9) in the same way as in the embodiment, the microcomputer 200b in step 300f detects A-D generated based on the received light voltage V from the photovoltaic cell 132.
The digital voltage ■ from the converter 200a is set to a predetermined voltage ■a
Compare with. In this case, the predetermined voltage Va corresponds to the predetermined amount TO of ultraviolet rays that is transmitted, which corresponds to the predetermined flow rate Qo of lubricating oil <for example, 1%) described in the first embodiment, and the predetermined voltage VO is stored in the ROM of the microcomputer 200b. Instead, it is stored in advance.

At this stage, if V≦Va, the microcomputer 200b determines rNOJ at step 300f, generates an engagement signal at step 300C, and activates the electromagnetic clutch, as in the first embodiment. 20 is engaged.

Therefore, the refrigeration cycle Rc circulates the refrigerant and lubricating oil under the operation of the compressor 10 as in the first embodiment. In such a case, as determined from rNOJ in step 300f, the amount of lubricating oil circulating in the refrigeration cycle Rc is Q>Qo as is clear from FIG.
The compressor 10 is sufficiently lubricated.

Further, in the above-mentioned operating state, the refrigeration cycle R
Because the amount of lubricating oil circulating through c has been unnecessarily reduced due to leakage, etc., the determination in step 300f is rY.
When ESJ is reached, the microcomputer 200b generates a lighting signal in step 300d and eliminates the engagement signal in step 300e, as in the first embodiment.

As in the first embodiment, the indicator lamp L lights up to visually confirm the lack of circulating lubricating oil in the refrigeration cycle Rc, and the electromagnetic clutch 20 is disengaged to cut off the compressor 10 from the engine and stop the operation. Let and protect. As a result, it is possible to prevent lock failure due to insufficient lubrication of the compressor IO, which tends to occur due to insufficient amount of circulating lubricating oil in the refrigeration cycle Rc.

As explained above, the oil flow sensor S according to the second embodiment is
Since the flow rate of the circulating lubricating oil in the refrigeration cycle Rc is detected by , and the compressor 10 is stopped when the flow rate is insufficient, the surplus components (
For example, by simply sealing the necessary and sufficient lubricating oil into the refrigeration cycle Rc without employing an oil separator, the heat exchange rate in the refrigeration cycle Rc can be maintained appropriately, and the compressor 10 can be prevented from locking due to lack of lubrication. While protecting
It can be operated normally.

Next, a modification of the second embodiment will be explained with reference to FIGS. 1O and 11. In this modification,
Instead of the expansion valve 60 shown in FIG. 1, an electromagnetic expansion valve 60
Its structural features lie in that it adopts A and the drive circuit 200e, and that the flowchart for specifying the modified computer program (see FIG. 9) is modified as shown in the flowchart shown in FIG. expansion valve 60
A controls the inflow amount of refrigerant and lubricating oil from the pipe P5 to the pipe P6 by the opening degree according to the operation of the linear solenoid 60b. In addition, the expansion valve 60A has a temperature sensing element 60c.
The temperature sensing element 60c detects the temperature of the refrigerant in the pipe P and generates a temperature detection signal. The A-D converter 200a is the photovoltaic cell 13 described in the second embodiment.
In addition to the light-receiving voltage (2) from 2, the temperature detection signal from the temperature sensing element 60c is digitally converted and generated as a digital temperature signal. The drive circuit 200e is the microcomputer 2
The opening of the expansion valve 60A, that is, the operation of the linear solenoid, is controlled under the control of the controller 00b.

The rest of the structure is the same as that of the second embodiment.

In this modified example configured as described above, similarly to the second embodiment, when the determination in step 300f (see FIGS. 9 and 11) becomes "NO", the microcomputer 200b 11), together with the engagement signal, an opening signal for opening the expansion valve 60A to keep the superheat constant is generated. Then, the expansion valve 60A responds to the opening signal and opens in response to the operation of the linear solenoid 60b by the drive circuit 200e. Therefore, under the operation of the compressor 10, the refrigerant and lubricating oil are circulated as in the second embodiment.

On the other hand, similarly to the second embodiment, step 300f (ninth
When the arithmetic processing in step 300d is completed after the determination in step 300g (see FIG. 11) becomes YESJ, the microcomputer 200b increases the opening degree of the expansion valve 60A in step 300g (see FIG. 11). In response to this, the drive circuit 2 generates an opening increase signal to
00e increases the opening degree of the expansion valve 60A. For this reason,
The amount of refrigerant and lubricating oil circulated from the pipe P passing through the expansion valve 60A to the pipe P6 increases. Therefore, step 300
Even if the determination at
Since the amount of refrigerant and lubricating oil returned to the compressor 1 increases,
0 can be protected from lock failures that tend to occur due to lack of lubricating oil without stopping the system.

Further, another modification of the second embodiment will be explained with reference to FIGS. 12 and 13. In this other modification, the compressor 10 shown in FIG. Its structural features lie in that it adopts the mold compressor 10A and the drive circuit 200f, and that the flowchart for specifying the modified computer program (see FIG. 9) is modified as shown in the flowchart shown in FIG. .

The compressor 10A operates in the same manner as described above by selectively engaging the electromagnetic clutch 20, and sucks the refrigerant in the pipe P together with lubricating oil with a capacity corresponding to the operation of the variable capacity mechanism 10a, thereby providing lubrication. The suction refrigerant is compressed while receiving the action, and the compressed refrigerant is discharged into the pipe P2 together with the lubricating oil. The drive circuit 20Of controls the operation of the variable capacity machine jM 10a under the control of the microcomputer 200b.

The rest of the structure is the same as that of the second embodiment.

In this modified example configured as described above, when the determination in step 300f (see FIGS. 9 and 13) becomes "NO", the microcomputer 200b performs step 300c (see FIGS. (see figure), generates a capacity increase signal to increase the capacity of the compressor 10A according to the load along with the engagement signal, and in response, the drive circuit 200f operates the compressor via the variable capacity mechanism 10a. , controls the capacity of the OA. Therefore, the capacity of the circulating refrigerant and circulating lubricating oil of the refrigeration cycle Rc is
It is specified by the capacity of A.

On the other hand, as in the second embodiment, when the arithmetic processing in step 300d is completed, the microcomputer 200b performs the operation of the compressor 1 in step 300h (see FIG. 13).
A capacity increase signal for greatly increasing the capacity of 0A is generated, and in response to this, the drive circuit 20Of greatly increases the capacity of the compressor 10A via the variable capacity mechanism 10a.

For this reason, the amount of compressed refrigerant discharged from the compressor 10A into the pipe Pz increases, circulates through the refrigeration cycle Re, and flows through the compressor 1. Significantly increases the amount of lubricating oil that returns to the OA together with the refrigerant. That is, even if YES is determined in step 300f, the amount of lubricating oil returned to the compressor 10A is increased by increasing its capacity to maintain proper lubrication in the compression i 10A, so the compression 10A is stopped. without letting
Protects against lock failures that tend to occur due to lack of lubricant.

In addition, in the above-mentioned other modified example, an example was explained in which the compressor 10A is adopted and its capacity is increased after the determination of YESJ in step 300f. Alternatively, the rotation speed of the compressor 10A may be increased.

Further, in each of the above-mentioned modifications, the opening degree of the expansion valve 60A or the capacity of the compressor 10A may be increased based on the oil flow sensor S and Q-I characteristics mentioned in the first embodiment. good.

Furthermore, in implementing the present invention, the present invention is applied not only to the refrigeration cycle of a near conditioner but also to various refrigeration cycles such as a refrigeration cycle of a vehicle refrigeration system, or a refrigeration cycle having an accumulator cycle. Good too.

Further, in implementing the present invention, the light source 123 is not limited to a hydrogen discharge tube, and may be any ultraviolet light source such as a xenon lamp.

Furthermore, in carrying out the present invention, the oil flow sensor S is
Both piping P4. It is not limited to 'P5, but may be placed between the condenser 40 and the evaporator 70.

Further, in implementing the present invention, the light receiving means is not limited to the photovoltaic cell 132, and an ultraviolet sensor such as a phototube or a photomultiplier tube may be employed as the light receiving means.

Furthermore, in carrying out the present invention, the light is not limited to ultraviolet light, and any wavelength of light may be used as long as the light intensity changes only in response to changes in the amount of lubricating oil.

In such a case, the circulating oil amount may be determined not only on the basis of the lubricating oil circulating amount, but also on the basis of, for example, the amount of change in light with respect to the lubricating oil circulation rate.

Furthermore, in implementing the present invention, the amount of lubricant may be determined based on a change in the amount of light received by the photoreceptor due to a change in the amount of light diffused by the lubricant.

[Brief explanation of the drawing]

Fig. 1 is a diagram corresponding to the claims, Fig. 2 is a block diagram showing the first embodiment of the present invention, and Fig. 3 is a cross section of the oil flow sensor taken along line 3-3 in Fig. 4. Figure 4 is a cross-sectional view taken along line 4-4 in Figure 3, Figure 5 is a graph showing the relationship between the fluorescence intensity of the ultraviolet fluorescent substance in lubricating oil and the flow rate of lubricating oil, and Figure 6 is a microcomputer. 7 is a sectional view showing the main part of the second embodiment of the present invention, and FIG. 8 is a flow chart showing the flow rate Q of lubricating oil containing an ultraviolet absorbing substance.
FIG. 9 is a flowchart showing the operation of the microcomputer in the second embodiment, and FIG. 10 is a block diagram showing a modification of the second embodiment. , FIG. 11 is a flow chart showing the operation of the microcomputer in the same modification, FIG. 12 is a block diagram showing another modification of the second embodiment, and FIG. 13 is a flow chart showing the action of the microcomputer in the same modification. FIG. Explanation of symbols 10, IOA... Compressor, 20... Electromagnetic clutch,
50... Gas-liquid separator, 60.60A... Expansion valve, 20
0b...Microcomputer. P3 to P6... Piping, Rc... Refrigeration cycle. S...Oil flow rate sensor.

Claims (1)

[Claims] In a refrigeration cycle in which a refrigerant and a lubricating oil are sealed and the refrigerant is circulated together with the lubricating oil in response to selective operation of a compression means, the circulation rate of the lubricating oil is defined as the amount of change in light transmitted through the lubricating oil. 1. A compressor protection device for a refrigeration cycle, comprising: a detection means for detecting the amount of change; and a control means for controlling the compression means so as to protect the compression means when the detected amount of change is out of an allowable range.