JPH04101092A - Oil cooled scroll compressor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an oil-cooled scroll compressor, and more particularly to an oil-cooled scroll compressor in which back pressure acting on an orbiting scroll can be controlled.

[Prior Art] Fig. 4 shows an oil-cooled scroll compressor according to the prior art.

In the figure, reference numeral 1 denotes a scroll-type compressor body, and the compressor body 1 includes a cylindrical casing 2, a fixed scroll 3 fixed to the negative side of the casing 2 in the axial direction, and the other side of the casing 2 in the axial direction. A drive shaft 4 is rotatably inserted into the casing 2 via a bearing and has a crank at its tip end inside the casing 2, and a plurality of scrolls are rotatably supported by the crank of the drive shaft 4 and are connected to a fixed scroll 3. Compression chamber 5,5. ... and defines a back pressure chamber 6 within the casing 2; an orbiting scroll 7 that extends from the casing 2 to the fixed scroll 3 and communicates with the compression chamber 5 on the low pressure side;
and a discharge port 9 formed at the center of the fixed scroll 3 and communicating with the compression chamber 5 on the high pressure side.

On the other hand, 10 is an oil separation tank provided in the compressor main body 1 so as to accommodate the negative side of the compressor main body 1 in the axial direction, and the oil separation tank 10 is a bottomed cylindrical tank having an air outlet 11A. It consists of a main body 11, an oil separation filter 12 provided on one end side of the tank main body 11 so as to cover the air outlet 11A, and a discharge side cover 13 provided so as to cover the air outlet 11A. And the oil separation tank 10
is supplied into the compressor main body 1 to store lubricating oil 14 for lubricating, cooling, and sealing each part, and also to separate the lubricating oil 14 in the compressed air discharged from the discharge port 9 by an oil separation filter 12. It has become.

Reference numeral 15 indicates a discharge pipe connected to the discharge side cover 13 to discharge the compressed air purified within the oil separation tank 10, and the distal end side of the discharge pipe 15 is a branch pipe. A branch pipe on one side of the discharge pipe 15 is connected to an air tank (not shown), and a branch pipe on the other side, in which an unloading solenoid valve 16 is provided in the middle, is connected to the suction port 8 side of the compressor main body 1. .

Furthermore, 17 is an oil passage whose inlet 17A opens downward in the oil separation tank 10, and the oil passage 17 branches halfway into a casing communication part 17B, a fixed scroll communication part 17C, and a cooler communication part 17D. An oil cooler 18 is connected to the cooler communication section 17D, and a return pipe 19 from the oil cooler 18 is connected to the casing communication section 1.
It is connected in the middle of 7B.

Reference numeral 20 denotes a temperature regulating valve consisting of an inlet 17A, a casing communication section 17B, and a three-way valve provided in the oil passage 17 between the fixed scroll communication section 17C side and the cooler communication section 17D side. 20 functions to adjust the amount of oil flowing from the inlet 17A to the oil cooler 18 according to the temperature of the lubricating oil 14 on the oil separation tank 10 side. Moreover, 21 is an oil filter located in the middle of the oil passage 17 between the temperature adjustment valve 20 and the inlet 17A.

Further, 22 is a back pressure suction bypass that communicates between the suction port 8 and the back pressure chamber 6, which are in a negative pressure state during compression operation, and 23 is a normally closed type electromagnetic bypass provided in the middle of the back pressure suction bypass 22. The suction bypass valve 23 is opened for a predetermined period of time when a starting switch (not shown) is closed, and leads back pressure to the suction port 8 (thereby reducing the starting load). The aim is to reduce the

Reference numeral 24 denotes an electric motor mounted on the oil separation tank 10 and started by a start switch. It has become.

The oil-cooled scroll compressor according to the prior art has the above-mentioned configuration, and the electric motor 24 rotates the drive shaft 4 to rotate the orbiting scroll 7 relative to the fixed scroll 3, thereby opening the suction port 8. The air sucked in through the compressor is compressed in the compression chambers 5.5, . The lubricating oil 14 in this compressed air is separated by an oil separation filter 12, and only the purified compressed air is combined into an air tank via a discharge pipe 15.

Further, during the above-described compression operation, the pressure of the air compressed within the compression chamber 5 applies a separating force to the orbiting scroll 7 to separate it from the fixed scroll 3 . For this reason, the pressure in the compression chamber 5 of the intermediate pressure section is guided into the back pressure chamber 6 through a large back pressure guide hole (not shown) provided in the orbiting scroll 7 to maintain a pressure balance with the compression chamber 5 side. , to prevent the orbiting scroll 7 from floating up.

On the other hand, at startup, the compressed air in the compression chamber 5 of the intermediate pressure section flows into the back pressure chamber 6 through the back pressure introduction hole.
The pressure inside the compression chamber 5 on the highest pressure side, that is, on the discharge port 9 side does not rise. As a result, the pressure inside the back pressure chamber 6 becomes higher than that on the compression chamber 5 side, the pressure balance is disrupted, and the orbiting scroll 7
is pressed against the fixed scroll 3 side, giving an overload to the electric motor 24. Therefore, when the start switch is closed, the suction bypass valve 23 is opened for a certain period of time, and the air in the back pressure chamber 6 is circulated to the suction port 8 side to prevent back pressure from being generated. We are trying to reduce the burden on staff at the same time.

Further, during the above-described compression operation, the lubricating oil 14 in the oil separation tank 10 is fed under pressure to the compressor body 1 side via the oil passage 17, but when the lubricating oil 14 is at a predetermined temperature or higher, the temperature regulating valve 20 is supplied to the cooler communication part 17D side by
After being cooled by the oil cooler 18, from the return pipe 19 to the casing communication section 17B and the fixed scroll communication section 17C.
It is supplied to the compressor main body 1 side via.

In this way, the lubricating oil 14 supplied from the oil passage 17 into the compressor main body 1 lubricates, cools, and seals each part, and then returns to the oil separation tank 1 from the discharge port 9 together with compressed air.
discharged inside.

[Problem to be solved by the invention]

By the way, in the above-mentioned conventional technology, for example, when the oil separation tank 10 runs out of oil, the oil flow resistance in the oil passage 17 disappears, and the compressed air in the oil separation tank 10 flows through the oil passage 17. This directly flows into the back pressure chamber 6, and as a result, the back pressure in the back pressure chamber 6 increases abnormally, and the orbiting scroll 7 is strongly pressed against the fixed scroll 3 side.

For this reason, in the conventional technology, the sliding surfaces of both scrolls 3.7 may wear abnormally, an overload may occur in the electric motor 24, causing an overcurrent to flow, and the electric motor 24 may be burnt out. Since the suction bypass valve 23 is opened for a certain period of time and the pressure inside the back pressure chamber 6 is mechanically reduced, unnecessary pressure reduction may occur.
The problem is that it is inefficient.

On the other hand, in order to solve the above problems, the applicant has
No. 32547 (hereinafter referred to as prior art), the compressor body is provided with a back pressure detection means for detecting the pressure in the back pressure chamber, and a suction bypass valve is opened and closed according to the detected pressure of the back pressure detection means. We proposed an oil-cooled scroll compressor.

However, the above-mentioned prior art has an unresolved drawback in that it takes time and effort to process and attach the back pressure detection means to the compressor body.

The present invention has been made in view of the above-mentioned problems of the prior art.The present invention can prevent the pressure increase in the back pressure chamber and maintain the back pressure constant, thereby preventing overloading of the electric motor. It is an object of the present invention to provide an oil-cooled scroll compressor that is capable of efficiently controlling back pressure during startup.

[Means to solve the problem]

The features of the configuration adopted by the present invention in order to solve the above-mentioned problems include: a current detection means that detects the current value supplied to the electric motor and outputs a detection signal; and suction bypass valve control means for opening and closing the suction bypass valve.

Preferably, the suction bypass valve control means is configured to stop the electric motor when the detection signal from the current detection means exceeds a predetermined current value even if the suction bypass valve is opened for a predetermined time. .

[Effect]

With the above configuration, the pressure in the back pressure chamber increases and the orbiting scroll is pressed against the fixed scroll, the electric motor becomes overloaded, and the electric motor current value detected by the current detection means reaches a predetermined current value. When the pressure exceeds the predetermined pressure, the suction bypass valve control means can open the suction bypass valve and reduce the pressure in the back pressure chamber to a predetermined pressure.

Further, when the pressure in the back pressure chamber decreases to a predetermined pressure, the overload state of the electric motor is eliminated, and the current supplied to the electric motor reaches a predetermined current value, the suction bypass control means detects the current value from the current detection means. Based on the detection signal, the suction bypass valve can be closed to allow the compressor main body to perform normal operation.

Furthermore, even if the suction bypass valve is opened, the electric motor can be stopped if the overload condition of the electric motor is not resolved and the current value of the electric motor exceeds a predetermined current value for a predetermined period of time or more.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 3. Note that the same reference numerals are given to the same components as those of the prior art described above, and the explanation thereof will be omitted.

In the figure, reference numeral 31 indicates a current sensor as a current detection means, which is made of a Hall element or the like attached to the electric motor 24, and the current sensor 31 is connected to the input side of a control unit 32 (to be described later) as shown in FIG. line (not shown)
connected via. The current sensor 31 detects the current value (■) supplied to the electric motor 24 as an electrical signal, and outputs this detection signal to the control unit 32.

32 is an arithmetic circuit including a CPU and a ROM.

The control unit 32 is composed of a memory circuit such as a RAM, and a memory area 32A is provided in the memory circuit of the control unit 32. Further, the program shown in FIG. 3 is stored in the memory circuit of the control unit 32, and a predetermined current value (2) is stored in the memory area 32A.

etc. are memorized. Then, the control unit 32 opens or opens based on the detection signal from the current sensor 31.
The valve closing signal is output to open and close the suction bypass valve 23, and even if the suction bypass valve 23 is opened, the current value I supplied to the electric motor 24 remains at a predetermined current value. is exceeded for a predetermined period of time or more, the electric motor 24 is stopped.

A warning lamp 33 is connected to the output side of the control unit 32 as a warning means, and the warning lamp 33 is turned on by a control signal from the control unit 32.
It is designed to warn surrounding workers, and is attached to, for example, the operation panel of the package (not shown).

The oil-cooled scroll compressor according to this embodiment has the above-mentioned configuration, and the orbiting scroll 7 is rotated by the electric motor 24 via the drive shaft 4, and the air sucked from the suction port 8 is delivered to each compression chamber 5. The basic operation of compressing and discharging from the discharge port 9 is not substantially different from that of the prior art.

Next, regarding the suction bypass valve control means,
This will be explained with reference to FIG.

First, in step I, the control unit 32 outputs a predetermined current value I from the storage area 32A. In step 2, the current value I of the electric motor 24 detected by the current sensor 31 is read in. Next, in step 3, the current value I of the electric motor 24 is set to a predetermined current value ■. If it is determined as rNOJ in step 3, it can be predicted that the electric motor 24 is not in an overload state and that the pressure in the back pressure chamber 6 is lower than the predetermined pressure. , step 1
Go back and repeat monitoring. On the other hand, in this step 3, rY
When it is determined to be EsJ, the pressure in the back pressure chamber 6 increases and the orbiting scroll 7 is pressed against the fixed scroll 3,
Since the electric motor 24 is in an overload state,
Proceeding to step 4, a valve opening signal is output, the suction bypass valve 23 is opened, and the pressure in the back pressure chamber 6 is released to the suction port 8 side. Then, in step 5, a timer t is set, and in step 6, the detection signal from the current sensor 31 is again
is read, and in step 7, the current value of the electric motor 24 is set to a predetermined current value ■. Determine whether it is smaller than . If rYEsJ is determined in step 7, this means that the pressure in the back pressure chamber 6 is normally reduced by the suction bypass valve 23 opened in step 4, so step 8
The timer t is reset at step 9, a valve closing signal is outputted, the suction bypass valve 23 is closed, the compressor main body 1 is placed in a steady operating state, and the process returns to step 1.

On the other hand, when it is determined that rNOJ is determined in step 7, the process moves to step 10, and the predetermined time t defined in step 10 is continued.

It is monitored whether the overload condition (I>I.) of the electric motor 24 continues. And in this step 10, r
When the determination is NOJ, the process returns to step 6 and enters a waiting loop.

On the other hand, if it is determined as rYESJ in this step 10,
For example, lack of lubricating oil 14 (out of oil) or orbiting scroll 7
If another abnormality has occurred such as galling between the fixed scroll 3 and the fixed scroll 3, proceed to step 11 to immediately stop the electric motor 24 and turn on the warning lamp 33 to alert surrounding workers. After reporting the abnormality, the timer t is reset in step 13, and the process ends.

Thus, according to this embodiment, the current value ■ supplied to the electric motor 24 is detected by the current sensor 31, and this current value ■
and the predetermined current value■. By comparing this, the load condition of the electric motor 24 can be detected, and based on this, the suction bypass valve 23 can be opened and closed to efficiently maintain the pressure in the back pressure chamber 6 at a predetermined pressure. In addition, even if the suction bypass valve 23 is opened to reduce the pressure inside the back pressure chamber 6, the detection signal ■ of the current sensor 31 is read again,
Predetermined time t. The overload state of the electric motor 24 (■>■
Since it monitors whether or not o) continues, it is possible to detect other abnormalities such as oil shortage and galling in addition to the abnormal increase in back pressure, and the warning lamp 33 is lit to warn surrounding workers. The information can be notified to persons, etc.

In addition, it is possible to prevent the orbiting scroll 7 from being strongly pressed against the fixed scroll 3 side and wear out, reliably prevent the electric motor 24 from being overloaded for a long period of time, and effectively prevent accidents such as burnout. In addition, since it is only necessary to attach the current sensor 31 to the electric motor 24, the above-mentioned back pressure control function can be easily added to a conventional oil-cooled scroll compressor, and it can be manufactured at low cost. In addition, the reliability and life of the oil-cooled scroll compressor can be significantly improved.

In the above embodiment, the suction bypass valve control means was described as being controlled by the program shown in FIG. It may also be configured by a hard circuit.

Further, in the above embodiments, the current sensor 31 as the current detection means has been described as being composed of a Hall element, etc. However, instead of this, for example, an optical current sensor using the Faraday effect or an ammeter may be used. A meter relay or the like may also be used.

Further, in the embodiment, the warning lamp 33 is used as a warning means.
However, instead of this, a warning buzzer, a voice synthesizer, etc. may be used.

On the other hand, in the embodiment described above, the back pressure suction bypass 22 is shown as being provided outside the casing 2 of the compressor main body 1, but it may be provided inside the casing 2 as an air passage.

Furthermore, in the embodiment described above, the suction bypass valve 23 was described as being composed of a normally closed solenoid valve, but the present invention is not limited to this. For example, the suction bypass valve may be composed of an air pilot type on-off valve. You can.

[Effects of the Invention 1] According to the above-described details, according to the present invention, there is provided a current detection means for detecting the current value supplied to the electric motor and outputting a detection signal, and Since it is composed of a suction bypass valve control means that opens and closes the suction bypass valve, it is possible to prevent abnormal wear of the orbiting scroll and fixed scroll due to increased back pressure and burnout accidents due to overload of the electric motor. Moreover, since the suction bypass valve is opened and closed by the current detection means, back pressure can be controlled efficiently.

Furthermore, even if the suction bypass valve is opened, if the current value of the electric motor detected by the current detection means exceeds the predetermined current value for a predetermined period of time, in addition to an abnormal increase in back pressure, other problems such as oil shortage or galling may occur. Abnormalities can also be detected and warnings can be given to surrounding workers.

[Brief explanation of drawings]

1 to 3 relate to embodiments of the present invention, in which FIG. 1 is a longitudinal sectional view of an oil-cooled scroll compressor according to this embodiment, FIG. 2 is a block diagram showing the circuit configuration, and FIG. A flowchart showing the suction bypass valve control process, and FIG. 4 is a longitudinal sectional view of an oil-cooled scroll compressor according to the prior art. DESCRIPTION OF SYMBOLS 1... Compressor body, 2... Casing, 3... Fixed scroll, 4... Drive shaft, 5... Compression chamber, 6...
... Back pressure chamber, 7... Orbiting scroll, 8... Suction port, 9... Discharge port, 10... Oil separation tank, 17...
・Oil passage, 22... Back pressure suction bypass, 23.
...Suction bypass valve, 24...Electric motor, 3
1... Current detection sensor (current detection means).

Claims (2)

[Claims] (1) A compressor body that compresses air while being supplied with oil, and a compressor body that is installed in the compressor body to store oil that is discharged from the compressor body together with the compressed air, and to store oil that is discharged from the compressor body together with the compressed air, and to compress air through an oil passage. The compressor body includes an oil tank that supplies oil to the compressor body, and an electric motor that rotates by external power supply and drives the compressor body, and the compressor body includes a casing, a fixed scroll fixed to the casing, , an orbiting scroll rotatably supported by the casing via a drive shaft, forming a plurality of compression chambers between the fixed scroll and a back pressure chamber within the casing; In an oil-cooled scroll compressor comprising a back pressure suction bypass communicating between a communicating suction port and a back pressure chamber, and a suction bypass valve provided in the back pressure suction bypass, the electric motor The current detection means detects the supplied current value and outputs a detection signal, and the suction bypass valve control means opens and closes the suction bypass valve based on the detection signal from the current detection means. An oil-cooled scroll compressor characterized by: (2) The suction bypass valve control means is configured to stop the electric motor when the detection signal from the current detection means exceeds a predetermined current value even if the suction bypass valve is opened for a predetermined time. The oil-cooled scroll compressor according to (1).