JPH09178689A - Oil detector for fluid machinery - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To correctly detect the state of oil to be actually pumped into an oil supply passage (5) in a drive shaft (4). SOLUTION: A capacitance type oil sensor 7 composed of flat double cylindrical electrodes 71, 72 is arranged in the vicinity of an oil suction port 6 of an oil pump 3, and the presence / absence of an oil surface and a liquid refrigerant in oil. It was made possible to detect the oil concentration in consideration of the penetration of oil. In particular, the oil pump 3 is actually used because of the two-layer separation of oil by using the alternative refrigerant.
Even when the refrigerant was pumped up to the above, this could be correctly detected, and it was suitable for the alternative refrigerant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil detection device for a fluid machine, which is mainly applied to a refrigerant compressor of an air conditioner or a refrigerator.

[0002]

Conventionally, an apparatus of this type is disclosed in, for example, Japanese Unexamined Patent Publication (Kokai) No. 7-98168, and an electrostatic charge composed of parallel plate electrodes is provided near the oil surface which is the upper layer of the oil sump. A capacitive oil sensor is provided. But,
With this product, even if the height of the oil surface of the oil sump is appropriate and the oil concentration when the refrigerant is uniformly dissolved in the oil can be correctly detected, two layers of oil are separated and accumulated in the upper layer of the liquid refrigerant. However, even if only the liquid refrigerant can actually be pumped into the oil supply passage in the drive shaft, there is a problem that the oil level is detected as a normal oil level and a normal oil concentration. In particular, when an oil that is incompatible with the refrigerant is used with the use of a CFC alternative refrigerant, the two-layer separation is likely to occur frequently, resulting in many false detections.

Further, in the case of a flat plate type electrode, in order to reduce the variation in capacitance (output) due to a dimensional error, it is required to manufacture the plate electrode while keeping the distance between the plates strictly.

On the other hand, in Japanese Patent Laid-Open No. 7-127927, oil is introduced from the bottom of the oil sump to an oil sensor so that the presence or absence of oil at the bottom of the oil sump can be detected. Since the container for arranging the sensor is arranged and the container and the casing are connected by piping, the detection equipment becomes large in scale, and the original behavior of oil and refrigerant changes due to the detection equipment. There is.

A main object of the present invention is to provide an oil detection device for a fluid machine which can correctly detect the state of the oil actually pumped into the oil supply passage in the drive shaft.

[0006]

According to the first aspect of the present invention,
In order to achieve the above main purpose, as shown in FIG. 1, the oil pumped up to the oil supply passage 5 in the drive shaft 4 via the oil pump 3 is stored in the bottom portion of the casing 1 in which the working fluid supply / discharge mechanism is installed. In the oil detection device of a fluid machine, a capacitance type oil sensor 7 is arranged near the oil suction port 6 of the oil pump 3. The working fluid supply / discharge mechanism is a mechanism that changes the volume of the compression chamber in the case of a compressor, and is composed of a pair of scrolls in a scroll compressor, a cylinder and an eccentric rotor in a rotary compressor, and a vacuum pump. In the case of No. 1, it comprises an impeller provided between the rotor and the stator, an exhaust passage, a pair of jig burn plates, a threaded cylinder, and the like. Oil pump 3
In addition to the centrifugal type as shown, the constant volume type may be used.

The invention according to claim 2 is the same as the invention according to claim 1, in order to make the capacitance type oil sensor 7 compact and to reduce the variation of the measurement accuracy due to dimensional error or the like. As shown in FIG. 3, the capacitance type oil sensor 7 is configured to have flat double cylindrical electrodes 71 and 72. The capacitance C of the double cylindrical electrodes 71, 72 is
If the diameter of the outer electrode 71 is r1, the diameter of the inner electrode 72 is r2, and the relative permittivity of the medium between the electrodes is εr, then C = 24.1.
εr / (log (r1 / r2)).

According to a third aspect of the present invention, in the second aspect of the invention, the space where the sensor is provided is reduced, and the state of the oil actually pumped into the oil supply passage 5 can be detected better. Therefore, as shown in FIG. 1, the double cylindrical electrodes 71 and 72 are arranged so as to surround the oil suction port 6 of the oil pump 3. Double cylindrical electrodes 71, 72
The oil suction port 6 and the oil suction port 6 are most preferably arranged concentrically as shown in the drawing, but they may not necessarily be arranged so as not to be aligned.

The invention according to claim 4 is the same as the invention according to claim 2 or 3, in order to favorably hold the two electrodes 71 and 72 concentrically, as shown in FIG. 71 and 72 were supported by the support body 8 arranged at a plurality of positions on the circumference. In the illustrated example, the support 8 is arranged at three locations on the circumference, but it is sufficient if it is two or more locations.

The invention according to claim 5 provides the first backup means in the case of running out of oil in the invention according to any one of claims 1 to 4, and as shown in FIG. An oil level control means 91 is provided to reduce the rotation speed of the drive shaft 4 to reduce the amount of pumped oil when the capacity type oil sensor 7 is detecting oil shortage. The rotation speed of the drive shaft 4 can be changed by controlling the motor 40 with an inverter.

The invention according to claim 6 provides the second backup means in the case of running out of oil in the invention according to any one of claims 1 to 4, and as shown in FIG.
When running out of oil with the capacitive oil sensor 7,
An oil level control means 92 is provided for increasing the circulation amount of the working fluid and increasing the amount of oil returned to the fluid machine. The circulation amount of the working fluid can be changed by adjusting the opening degree of a valve V (expansion valve) interposed in a circuit (a refrigeration circuit in the drawing) for circulating the working fluid that is supplied to and discharged from the fluid machine.

The invention according to claim 7 provides the third backup means in case of running out of oil in the invention according to any one of claims 1 to 4, and as shown in FIG.
When running out of oil with the capacitive oil sensor 7,
The oil level control means 93 is provided to increase the opening degree of the oil return passage B connecting the oil recovery device S and the casing 1 which are interposed in the working fluid circulation path to increase the oil return amount. Increasing the opening degree of the oil return passage B is a concept including the case where the on-off valve D provided in the oil return passage B is switched from closed to open to switch the passage from the closed state to the communication state.

The invention according to claim 8 is the same as the invention according to any one of claims 5 to 7, and is shown in FIG. 4 in order to avoid a situation such as seizure which is difficult to recover due to oil shortage. As described above, the protective device 94 is provided to stop the operation when the oil level control means does not eliminate the oil shortage. Stopping the operation means stopping the rotation of the drive shaft 4 by cutting off the power supply to the motor 40 or the like.

According to a ninth aspect of the present invention, in the invention according to any one of the first to fourth aspects, an appropriate backup is made according to the progress of running out of oil, and finally the device is protected. As shown in FIG. 4 and FIG. 5, when the capacitance TM oil sensor 7 measures the duration time during which the oil shortage is detected and the oil shortage duration T is less than the first set time T1, the oil As the surface control 1, the rotation speed of the drive shaft 4 is reduced, and when the oil shortage duration T is equal to or more than the first set time T1 and less than the second set time T2, the oil level control 2 is performed to increase the circulation amount of the working fluid. When the cut-off continuation time T is equal to or more than the second set time T2 and less than the third set time T3, the oil return passage B from the oil recoverer H, which is interposed in the circulation path of the working fluid as the oil level control 3, is opened to open the oil. The operation is stopped when the disconnection duration time T is the third set time T3 or more. Protection device is equipped with an oil level controlling means 9
Configuration. As shown in FIG. 5, the oil-depletion duration is determined by using the counter value T of the timer TM that starts counting when the oil level sensor output S from the capacitance type oil sensor 7 becomes equal to or less than the specified value X. Can be recognized. At this time, the timer set time and the oil level control method vary depending on the system, and thus they may be arbitrarily changed.

The invention according to claim 10 is, in the invention according to claim 8 or claim 9, for avoiding a long-term suspension of operation to provide continuity, as shown in FIGS. 4 and 5.
After the operation was stopped, the restarting means 95 for restarting the operation by eliminating the oil shortage was provided. The elimination of oil shortage can be recognized when the oil level sensor output S exceeds a specified value X, as shown in FIG.

According to an eleventh aspect of the present invention, in order to detect the oil concentration in the invention according to any one of the first to tenth aspects, not only the presence or absence of oil but also the amount of the refrigerant dissolved in the oil is taken into consideration. As shown in FIGS. 6 and 7, the oil concentration estimating means 96 for estimating the oil concentration from the detection value of the capacitance type oil sensor 7 is provided. The capacitance C has a temperature drift such that it becomes larger as the temperature Td is lower even if the oil concentration is the same. Therefore, it is desirable to perform the temperature correction as shown in FIG. 6, and by doing so, the accurate oil concentration can be detected. Note that the characteristic diagram of FIG. 7 shows that the alternative refrigerant R22 is used as the working fluid, and in particular, since such an alternative refrigerant has polarity and the polarization state changes, the relative permittivity εr greatly changes with respect to the oil concentration. It is supposed to do.

[0017]

According to the first aspect of the present invention, as shown in FIG. 1, since the capacitance type oil sensor 7 is arranged in the vicinity of the oil suction port 6 of the oil pump 3, the liquid refrigerant and the oil Is not affected by the separation of the two layers, and the special container for arranging the sensor is not provided, and the original behavior of the oil and the refrigerant is not changed. The state of the oil pumped up and used for lubrication or the like can be accurately detected.

According to the second aspect of the present invention, as shown in FIGS. 2 and 3, the capacitance type oil sensor 7 has the flat double cylindrical electrodes 71 and 72. In addition to being formed, it is possible to reduce variations in measurement accuracy due to dimensional errors and the like, as compared with those using parallel plate electrodes.

According to the third aspect of the invention, as shown in FIG. 1, since the double cylindrical electrodes 71 and 72 are arranged so as to surround the oil suction port 6 of the oil pump 3, the double oil suction port 6 is provided. The heavy cylinder electrodes 71, 72 can be located in the central space portion, and the heights of the oil suction port 6 and the double cylinder electrodes 71, 72 can be made substantially the same. Therefore, it is possible to save space in the sensor arrangement portion, and it is possible to detect the state of the oil actually pumped into the oil supply passage 5 via the oil suction port 6 more favorably.

According to the fourth aspect of the present invention, as shown in FIG. 2, the double cylindrical electrodes 71 and 72 are supported by the supports 8 arranged at a plurality of positions on the circumference. Two electrodes 71,7
Even if the center of 2 is slightly deviated, the electrode gap does not change, so a strict mounting system is not required.

According to the fifth aspect of the invention, as shown in FIG. 4, when the electrostatic capacity type oil sensor 7 detects the oil shortage, the rotation speed of the drive shaft 4 is reduced to reduce the pumping oil amount. Therefore, the oil level of the oil accumulated in the bottom portion of the casing 1 can be slowed down, and the backup against oil shortage can be achieved.

According to the sixth aspect of the invention, as shown in FIG. 4, when the electrostatic capacity type oil sensor 7 detects the oil shortage, the circulation amount of the working fluid is increased to return to the fluid machine. Since the amount of oil is increased, it is possible to promote the rise of the oil level of the oil stored in the bottom of the casing 1, and it is possible to back up against oil shortage.

According to the seventh aspect of the present invention, as shown in FIG. 4, when the electrostatic capacity type oil sensor 7 detects the oil shortage, the oil recovery device S is provided in the circulation path of the working fluid. Since the opening degree of the oil return passage B connecting to the casing 1 is increased to increase the oil return amount, it is possible to promote the oil level rise of the oil accumulated in the bottom portion of the casing 1, and to back up against oil shortage.

According to the eighth aspect of the present invention, as shown in FIG. 4, the protective device 94 is provided to stop the operation when the oil level control means does not eliminate the oil shortage.
It is possible to prevent a situation such as seizure or the like that causes a hard-to-recovery defect due to oil shortage.

According to the ninth aspect of the invention, as shown in FIG. 5, when the oil shortage duration T is less than the first set time T1,
As the oil level control 1, the rotation speed of the drive shaft 4 can be reduced to slow down the oil level reduction of the oil accumulated at the bottom of the casing 1. The oil shortage duration T is the first set time T1 or more and the second set time T
When it is less than 2, it is possible to increase the circulation amount of the working fluid as the oil level control 2 to promote the oil level rise of the oil accumulated in the bottom portion of the casing 1. Oil out duration T is the second set time T2
When the time is less than the third set time T3 as described above, as the oil level control 3, the oil return passage B from the oil recovery device H interposed in the circulation path of the working fluid is opened to raise the oil level of the oil accumulated in the bottom portion of the casing 1. Can be encouraged. Since the operation is stopped when the oil depletion duration time T is equal to or longer than the third set time T3, it is possible to prevent a situation such as seizure which is difficult to recover due to oil depletion. In this way, appropriate backup can be achieved according to the progress of oil depletion, and finally the device can be protected.

According to the tenth aspect of the invention, as shown in FIG. 5, after the operation is stopped, the operation is restarted by eliminating the oil shortage. Therefore, it is possible to avoid a long stoppage of the operation and to provide the operation with continuity. You can

According to the eleventh aspect of the invention, as shown in FIG. 7, the oil concentration and the relative permittivity εr have a correlation, so that the oil concentration can be estimated from the detection value of the capacitance type oil sensor 7.
In this way, by providing such an oil concentration estimating means 96, it is possible to detect not only the presence or absence of oil but also the oil concentration in consideration of the amount of the refrigerant dissolved in the oil.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of application to a refrigerant compressor, in which an oil sump 2 is provided at the bottom of a casing 1 in which a compression mechanism, which is a mechanism for supplying and discharging a working fluid, is provided. The oil to be pumped is stored in the oil supply passage 5 in the drive shaft 4 via the oil pump 3. The cylindrical body 11 of the casing 1 is connected to the lower base member 12 via a flange portion 13.
The oil pump 3 is a centrifugal pump having an oil suction port 6 at the lower end. The drive shaft 4 is coupled to the rotor 41 of the motor 40. 42 is a stator of the motor 40. Also, 43 is
It is a lower housing having a radial bearing 44 and a thrust bearing 45 of the drive shaft 4.

In the vicinity of the oil suction port 6 of the oil pump 3, a capacitance type oil sensor 7 is arranged. This oil sensor 7 has flat double cylindrical electrodes 71, 72, and these electrodes 71, 72 are arranged concentrically with the axis of the drive shaft 4 so as to surround the oil suction port 6 of the oil pump 3. ing. As shown in FIGS. 2 and 3, terminal bolts 73 are provided on the outer side of the outer electrode 71 in the radial direction, and the terminal portion 75 of the lead wire 74 made of a shield wire is connected to the washer 76 and the nut 77. It is fixed by using. Terminal bolts 78 are provided on the inner side of the inner electrode 72 in the radial direction, and lead wires 79, which are also shield wires, are fixed thereto. As shown in FIG. 1, the lead wires 74 and 79 are connected to a connector portion or a take-out portion 14 provided on the lower side of the casing 1.

As shown in FIGS. 2 and 3, the double cylindrical electrode 7
1, 72 are three support bodies 8 arranged at three locations on the circumference.
Supported by Each support 8 is an L-shaped support leg 8
0, outer insulator 81, gap insulator 82, inner insulator 8
3, insulating sleeve 84, coupling bolt 85, pad plate 8
6, the nut 87 is a component, and the base portion of the support leg 80 is attached to the base member 12 using the attachment bolt 88. Each insulator 81, 82, 83, 84 is made of Teflon or the like. Reference numeral 89 designates the electrodes 71 and 72 and the oil suction port 6
It is a pedestal that aligns the height with.

An impedance meter was connected to the connector section or the take-out section 14 as the output section of the capacitance type oil sensor 7, and the value was evaluated. As a result, the results shown in Table 1 below were obtained.

[0032]

[Table 1]

Since the oil and the liquid refrigerant are mixed during the operation when there is an oil level in the actual festival, the output of the impedance meter is the oil 1
The value is larger than that at the time of 00% (15 mA). The value becomes 20 mA or more in a wet operation in which more refrigerant melts. When the oil level runs out, the value will be 15 mA or less,
It will approach 4mA without oil level. These values change slightly due to the influence of temperature drift, but the tendency is the same.
In this way, it is possible to satisfactorily determine whether or not there is appropriate oil in the oil sump 2.

Next, when the oil level and the oil concentration are detected by the change in capacitance, the evaluation results of the water content and the contamination quantity, which are factors that may affect the output other than the temperature drift, are shown below. Shown in.

First, in order to evaluate the influence of the water content in oil, the measurement was carried out at the three points shown in Table 2 below.

[0036]

[Table 2]

As shown in Table 2, there is almost no difference in output when the water content in oil is 200 ppm or less. If a large amount of water around the saturated water content of about several thousand ppm is mixed and water drops are formed between the electrodes 71 and 72, the conductive substance intervenes, and the output obviously increases. is expected. However, it can be judged that the change in water content has no effect on the output of this sensor in an environment in which it is controlled to several tens of ppm or less like an actual machine.

Next, the influence of the amount of contamination will be evaluated. The measurement was performed by mixing standard contaminants (mainly line contaminants such as cutting oil and cleaning oil) in the oil. The results are shown in Table 3 below.

[0039]

[Table 3]

As shown in Table 3, there is almost no output difference when the contamination amount is 20000 ppm or less. This time, as a result of mixing standard contaminants that do not contain metal powder with extremely high conductivity, no difference in sensor output appeared.
Also, since the control standard is about 1000 ppm, it can be judged that there is no problem. However, if the sliding part abnormally wears and a large amount of metal powder is mixed in the oil, it is expected that the output will obviously increase. In other words, it means that it is possible to detect the inclusion of wear powder in the oil by the capacitance.

FIG. 4 shows a compressor P, which is a fluid machine incorporating the above capacitance type oil sensor 7, and constitutes a refrigerating circuit together with a condenser N, an expansion valve V and an evaporator E. The discharge-side high-pressure gas pipe of the container P is provided with an oil recovery device H that recovers the oil that has flowed out together with the refrigerant. And
The bottom of the oil recovery unit H and the casing 1 of the compressor P are connected by an oil return passage B, and an on-off valve D made up of an electromagnetic valve interposed therebetween is opened and closed to compress the oil that has flowed out. It can be returned to machine P. The rotation speed of the motor 40 of the compressor P is variable by inverter control.

Then, the oil level control means 9 with a protective device for controlling the motor 40 of the compressor P using the capacitance type oil sensor 7 and the timer TM as inputs is constituted by using a microcomputer or the like, and on the program thereof. , Has built the following means.

That is, as shown in FIG. 5, the oil level sensor output S from the capacitance type oil sensor 7 becomes less than or equal to the specified value X set at around 10 mA, and oil shortage is detected, and the duration T thereof is the first. When the time is less than the set time T1, as a first step of the oil level control, as shown in FIG. 4, a rotation speed control unit 91 that reduces the rotation speed of the drive shaft 4 to reduce the pumped oil amount is provided.

Further, the oil shortage duration T is the first set time T1.
When the time is less than the second set time T2 as described above, as the second stage of the oil level control, as shown in FIG. 4, the opening degree of the expansion valve V is increased to increase the circulation amount of the working fluid, and then to the compressor P. A circulation amount control means 92 for increasing the amount of return oil is provided. The control in the second stage is performed in combination with the control by the rotation speed control means 91 in the first stage.

Furthermore, the oil shortage duration T is the second set time T
An oil return control means 93 is provided to open the on-off valve D to open the oil return passage B extending from the oil recovery unit H when the time is 2 or more and less than the third set time T3 to increase the amount of oil returned to the compressor P. . The control in the third stage is performed in combination with the control by the rotation speed control unit 91 in the first stage and the circulation amount control unit 92 in the second stage.

Furthermore, when the oil depletion duration time T is equal to or longer than the third set time T3, a protection device 94 for stopping the operation by stopping the motor 40 of the compressor P is provided, and after the operation is stopped, the oil is depleted. A restarting means 95 for restarting the operation by eliminating the disconnection is provided.

By the way, the capacitance type oil sensor 7 of the present invention can measure not only the presence or absence of the oil level but also the oil concentration. As shown in FIG. 7 to 7, an oil concentration estimating means 96 for estimating the oil concentration based on the characteristic diagram shown in FIG. 7 is also provided so that it can be applied to various compressor controls.

In the above, as shown in FIG. 1, the cylindrical body 11 of the casing 1 and the lower base member 1 are used.
2 and the dome-shaped lower lid 120 may be joined by welding, as shown in FIG.

[Brief description of the drawings]

FIG. 1 is a sectional view of an oil detection device according to the present invention.

FIG. 2 is a plan view of the relevant part.

FIG. 3 is a cross-sectional view taken along line A, A of FIG.

FIG. 4 is a refrigeration circuit diagram including an oil detection device.

FIG. 5 is a flowchart of oil level control.

FIG. 6 is an explanatory diagram of an oil concentration estimating means.

FIG. 7 is an oil concentration vs. relative dielectric constant characteristic diagram for explaining the principle of oil concentration estimation.

FIG. 8 is a sectional view of a main part showing another embodiment.

[Explanation of symbols]

1; casing, 3; oil pump, 4; drive shaft, 5; oil supply passage, 6; oil suction port, 7; capacitance type oil sensor, 7
1, 72; double cylindrical electrode, 8; support, 9; oil level control means with protective device, 91, 92, 93; oil level control means, 9
4; protection device, 95; restarting means, 96; oil concentration estimating means, TM; timer, H; oil recovery device, B; oil return passage

Claims (11)

[Claims] 1. A fluid machine in which oil is pumped up to an oil supply passage (5) in a drive shaft (4) through an oil pump (3) at the bottom of a casing (1) containing a mechanism for supplying and discharging a working fluid. Oil detection device for a fluid machine, wherein an electrostatic capacitance type oil sensor (7) is arranged in the vicinity of the oil suction port (6) of the oil pump (3). . 2. The oil detecting device for a fluid machine according to claim 1, wherein the capacitance type oil sensor (7) has a flat double cylindrical electrode (71, 72). 3. The oil detecting device for a fluid machine according to claim 2, wherein the double cylindrical electrodes (71, 72) are arranged so as to surround the oil suction port (6) of the oil pump (3). 4. The oil detection device for a fluid machine according to claim 2 or 3, wherein the double cylindrical electrodes (71, 72) are supported by supports (8) arranged at a plurality of positions on the circumference. . 5. An oil level control means (91) for reducing the pumping oil amount by lowering the rotational speed of the drive shaft (4) when the capacitance type oil sensor (7) is detecting oil shortage. The oil detection device for a fluid machine according to claim 1, wherein the oil detection device is provided. 6. An oil level control means (92) for increasing a circulation amount of a working fluid and increasing an amount of oil returned to a fluid machine when an oil shortage is detected by a capacitance type oil sensor (7). The oil detection device for a fluid machine according to any one of claims 1 to 4, further comprising: 7. An oil return passage for connecting a casing (1) with an oil collector (H) interposed in a working fluid circulation path when an oil shortage is detected by a capacitance type oil sensor (7). The oil detection device for a fluid machine according to any one of claims 1 to 4, further comprising an oil level control means (93) for increasing the opening degree of (B) to increase the oil return amount. 8. The oil detection device for a fluid machine according to claim 5, further comprising a protection device (94) for stopping the operation when the oil level control means does not eliminate the oil shortage. 9. A timer (TM) for measuring the duration of oil depletion detection by a capacitance type oil sensor (7), and a drive shaft (4) when the oil depletion duration is less than a first set time. Lowers the number of revolutions and increases the circulation amount of the working fluid when the oil depletion duration is equal to or longer than the first set time and shorter than the second set time,
Oil recovery device (H) installed in the circulation path of the working fluid when the oil depletion duration is equal to or longer than the second set time and shorter than the third set time
Open the oil return passage (B) from the
The oil detection device for a fluid machine according to any one of claims 1 to 4, further comprising a protection device-equipped oil level control means (9) for stopping the operation when the set time is exceeded. 10. A restarting means (95) for restarting the operation by eliminating the oil shortage after the operation is stopped is provided.
Alternatively, the oil detection device of the fluid machine according to claim 9. 11. The oil of a fluid machine according to claim 1, further comprising an oil concentration estimating means (96) for estimating an oil concentration from a detection value of the capacitance type oil sensor (7). Detection device.