JPH06249153A - Variable capacity compressor - Google Patents

Abstract

(57) [Summary] [Purpose] In a variable displacement compressor that has the function of controlling the discharge pressure to a constant value even if the amount of compressed gas consumed increases or decreases, the inspection time and the parts replacement time need only be determined by the operating time. I can't decide. SUMMARY OF THE INVENTION It is an object of the present invention to accurately display the inspection time of a variable displacement compressor and the replacement time of parts to improve reliability. [Construction] The inverter 4 drives the electric motor 3, and the rotation of the electric motor 3 rotates the rotor of the compressor body 2 to suck air from the suction port 8 and discharge it from the discharge port 9. The discharge pressure is the pressure sensor 11
The control device 5 changes the rotation speed of the rotor to control the discharge pressure to be constant. The rotation of the rotor is detected by the sensor 21, and the total number of rotations is counted by the counter 24.
The judgment device 25 monitors the total number of revolutions, and when the judgment criterion is satisfied, the display device 26 displays a message transmitted to the user. [Effect] A compressor that is highly reliable and easy to use is realized by accurately informing the user of the inspection time and the replacement time of consumable parts that cannot be determined only by the operating time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, in a variable displacement compressor having a function of controlling the discharge pressure to be constant even if the amount of compressed gas consumed increases or decreases, accurately displays the inspection time and the parts replacement time. The compressor is reliable and easy to use.

[0002]

2. Description of the Related Art The basic function of a compressor is to inhale, compress, and discharge gas. Compressed gas (hereinafter,
This is called compressed gas. It is often air, but it may be used for chemical plants to compress other gases. The discharge pressure of) is preferably constant, and is adjusted by a compressor or a regulator provided in the subsequent stage. When the compressor is operated at a constant rotation speed, the discharge pressure decreases when the amount of compressed gas consumed exceeds the amount discharged, and conversely, when the amount consumed is less than the amount discharged, the discharge pressure becomes excessive. Therefore, there are some methods for keeping the discharge pressure constant even if the consumption amount of the compressed gas changes.

In the conventional air compressor, in order to control the discharge amount, a "throttle valve control system" for opening and closing the throttle valve provided at the suction port is widely used while keeping the rotor rotation speed constant. is doing. However, 100% even when the discharge amount is small
Since the rotation speed is the same as that at the time of output, there are many mechanical losses and there is a problem in economy.

From the viewpoint of economy and ease of use, as a method suitable for the variable displacement compressor, there is a method of controlling the discharge flow rate by feeding back the discharge pressure and increasing or decreasing the rotation speed of the rotor. It is disclosed in Japanese Patent Publication No. 55-164792.
In this known example, when the consumption amount increases, a phenomenon such as a decrease in the discharge pressure appears. Therefore, by detecting it, the rotor rotation is accelerated, the discharge amount is increased, and the discharge pressure is kept constant. In order to realize the method, it is stated that the rotation of the rotor can be continuously changed by the inverter.

However, this publicly known example does not take into consideration the periodic inspection, the method of determining the replacement time of consumable parts, and the method of specifying.

[0006]

In order to use the compressor safely and with high reliability, regular inspection and replacement of consumable parts are indispensable. The interval between these operations is related to the total number of revolutions of the rotor. In the conventional throttle valve control system, the rotation speed was constant, so the operating time of the compressor was low.
Proportional to the total number of rotations of the motor. Therefore, it suffices to display the time required for periodic inspections by the value of the operating hour meter attached to the compressor.

However, in the method of controlling the discharge pressure by changing the rotational speed of the rotor as in the above-mentioned known example, the operating time of the compressor is not proportional to the total rotational speed of the rotor. Therefore, the conventional operation time meter has a problem that the indication of periodic inspections is incomplete.

In view of the above problems, the present invention considers both the operating time and the total number of revolutions of the rotor, and makes it possible to properly indicate the time for periodic inspection and replacement of consumable parts. The purpose is to realize the machine.

[0009]

As a means for achieving the above object, a variable displacement compressor is constructed as follows.

A detection means such as a rotation detection sensor for detecting the rotation of the rotor and a storage means such as a counter (integrating tachometer) for counting and storing the output thereof are provided. The storage means stored in the storage means is used as a judgment material, and a judgment means for judging whether or not a message to the user is to be clearly displayed is provided by comparing it with a predetermined judgment standard.
As the judgment material, it is possible to add the operating time and the temperature during the operation to the stored contents. If a decision is made, a message
It is provided with a display unit such as a warning lamp or a display for clearly indicating the message to the user.

A rotation speed sensor for detecting the rotation speed of the rotor is used instead of the means for detecting the total rotation speed of the rotor.
Alternatively, a means for detecting the rotation speed command value may be provided. In that case, it is also provided with an arithmetic means capable of integrating the detected value.

[0012]

The above means operates as follows. When the compressor is operated, the rotation of the rotor is detected by the detecting means and the rotation information is transmitted to the integrating tachometer. The total tachometer stores the total number of revolutions in the past, and adds the current revolution to it and stores it.
The total number of rotations is gradually increased. When the judging means judges that the total number of revolutions has reached the preset value, the display device displays and a message is transmitted to the user. The displayed contents include the time when periodic inspection is required and the time when consumable parts are replaced. The display method is by turning on a warning lamp, or by displaying a message by letters or pictures.

When a rotating speed detecting means or a rotating speed command value detecting means is provided in place of the total rotating speed detecting means, the following operation is performed. First, the difference between the rotation speed and the rotation speed command value will be described. The rotation speed follows the rotation speed command value and becomes the same value during steady operation, but deviates due to a slight time delay during acceleration or deceleration. However, the error is small, and since the signs of the errors are opposite during acceleration and deceleration and cancel each other out, there will be no large error when integrated. Therefore, there is no difference whether the rotational speed or the rotational speed command value is adopted. Therefore, only the case of the rotational speed will be described here, but the same operation also applies when the rotational speed command value is used.

When the compressor is operating, the rotation speed is detected at time intervals determined by the rotation speed detecting means. When the value obtained by multiplying the value by the time interval is integrated, the value is integrated over time, and the total number of rotations is obtained. Here, if the time interval to be detected is infinitely small, there is no error, but it is difficult to realize and a certain degree of error is allowed, so there is no practical problem if the time interval is sufficiently short. The total number of rotations obtained by the above method is used as a criterion.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a system diagram of the variable displacement air compressor of this embodiment. The compressor 1 is composed of a compressor body 2 and some auxiliary machines. The compressor body 2 is a variable capacity compressor such as a screw type or a scroll type, and the discharge amount can be increased or decreased in proportion to the rotation speed. The rotor (not shown) of the compressor body 2 is connected to the output shaft of the induction motor 3 by the power shaft 12. An air suction port 8 is provided at one end of the compressor body 2 and a discharge port 9 is provided at the other end thereof, and each communicates with an internal compression chamber. The power receiving terminal of the electric motor 3 is connected to the output terminal of the inverter 4 by a power line. The command value input terminal of the inverter 4 is connected to the speed command value output terminal of the control device 5.
In addition, auxiliary wiring such as a communication line is connected between the inverter 4 and the control device 5. The power line of the commercial AC power 6 supplied from the outside is connected to the power receiving terminal of the inverter 4.
Although electric power is supplied to other auxiliary equipment as well, description thereof is omitted.

The suction port 8 of the compressor body 2 is an air cleaner 7.
Piped to. A discharge pipe 10 is connected from the discharge port 9 to the outside, and a pressure sensor 11 is provided on the way. The output information of the pressure sensor 11 is wired so as to be sent to the control device 5 as an electric signal. The wiring is also used to supply electric power from the control device 5 to the pressure sensor 11.

Power shaft 12 connecting electric motor 3 and compressor body 2
A reflection tape 22 is attached to one position on the surface of, and a light reflection type sensor 21 is provided to face it in a non-contact manner. Sensor 2
1 is connected to the sensor amplifier 23, and the output terminal of the sensor amplifier 23 is connected to the input terminal of the counter 24. Further, the output terminal of the counter 24 is connected to the input terminal of the judgment device 25, and the input terminal of the display device 26 for displaying the judgment result is connected to the output terminal of the judgment device 25. The judgment device is composed of a microcomputer and peripheral electronic circuits, and has necessary judgment criteria and calculation programs built therein. The display device 26 is an LCD
(Liquid crystal display device) with control electronics. The display device 26 includes a display changeover switch 27 that can be operated by the user.
Are connected.

A temperature sensor 31 and a converter 32 which is connected to the temperature sensor 31 and converts an output into an electric signal are provided inside the compressor body 2. The output signal line of the converter 32 is connected to the signal input terminal of the judgment device 25. An electronic timepiece 33 is attached to the judging device 25, and the judging device 2 can obtain information on the cumulative operating time and the current time.
It has a function to tell 5.

The present compressor basically operates as follows. The commercial AC power 6 is in accordance with a command from the control device 5,
The voltage and frequency are converted by the inverter 4, and the electric motor 3 is driven at the target rotation speed. The rotation of the electric motor 3 is transmitted to the rotor of the compressor body 2 via the power shaft 12. The compressor body 2 sucks air from the suction port 8 by the action of the rotation of the rotor, compresses it, and discharges it from the discharge port 9. The air is sucked into the air cleaner 7 from the atmosphere to remove dust and then sucked into the suction port 8. On the other hand, the compressed air discharged from the discharge port 9 is sent to the outside from the discharge pipe 10. The discharge pressure at that time is constantly monitored by the pressure sensor 11, and the obtained discharge pressure data is sent to the control device 5.

The control system for keeping the discharge pressure constant operates as follows. When the amount of compressed air consumed increases and the pressure inside the discharge pipe 10 decreases, the pressure sensor 11
Is detected by the controller 5, and the controller 5 commands the acceleration of the rotor rotation speed. In response to this, the inverter 4 increases the output frequency, accelerates the electric motor 3, and accelerates the rotor of the compressor body 2. Since the compressor main body 2 is a variable displacement compressor, the discharge amount increases as the rotation speed increases, and the discharge pressure recovers to a specified value. When the amount of compressed air used decreases, it works in reverse, and the rotor rotation speed is reduced to respond, so the discharge pressure decreases and approaches the set value. In this way, the discharge pressure is controlled to remain constant regardless of the amount of compressed air consumed.

The display system, which is the main part of the present invention, operates as follows. The sensor 21 is supplied with power from the sensor amplifier 23 and emits light. The light beam is directed to the power shaft 12, and is reflected only when the reflection tape 22 faces the sensor 21 side, and returns to the sensor 21. The information is sent to the sensor amplifier 23, and the sensor amplifier 23 outputs a pulse when the reflection tape 22 faces the sensor side. Counter 24
Counts and stores the output pulses. Therefore, the total number of rotations of the rotor of the compressor body 2 becomes the output of the counter 24. As the compressor 1 operates, the total number of rotations gradually increases.

The temperature sensor 31 constantly monitors the temperature inside the compressor body 2 and continues to send information to the judging device 25 through the converter 32. Further, the clock 33 provides the cumulative total of the driving time in response to the request of the determination device 25.

The judging device 25 monitors the total number of revolutions stored in the counter 24 and compares it with the judging standard of the judging device 25. Here, it is the simplest that the judgment criterion is whether or not the total number of revolutions exceeds a predetermined numerical value, and it can be used as a judgment criterion for bearing replacement or the like. However, for a phenomenon involving chemical changes, such as when determining the replacement time due to deterioration of the lubricating oil, the determination criteria determined by taking operating time and temperature conditions during operation into consideration are suitable. Therefore, the total number of revolutions is added with the information on the temperature and accumulated operating time from the converter 32 and the timepiece 33 to make a comprehensive determination.

When the judgment standard is reached, the judgment device 25 sends a display command to the display device 26. The display device 26 displays a message transmitted to the user according to the content of the received instruction. The message is stored in advance. When the message requires an emergency, it may be provided with a function of outputting a warning by sound or light to call the attention of the user. Further, in order to avoid danger, a function of stopping or decelerating the operation of the compressor may be provided.

Even before the display device 26 displays a message, it is useful to estimate the timing of inspection and parts replacement. In that case, the user selects the display changeover switch 2
By selecting the target item in 7, the counter 2
It is also possible to display the stored contents of No. 4 or to predict and display the time from the past usage state to the inspection time.

According to the present embodiment, the inspection time and the parts replacement time are determined from a lot of information, so that the display can be performed at an appropriate time.

In the present embodiment, if the counter 24, the judgment device 25 and the timepiece 33 are combined into one microcomputer computer or one-chip microcomputer, the size can be reduced at low cost and the reliability can be improved. In addition, the combination of other components can be similarly put together.

In this embodiment, since an electronic circuit is used for detecting and storing the total number of revolutions, depending on the operating environment, the program may run away, the stored contents may be destroyed by strong electromagnetic waves, or the stored contents may be exhausted by the built-in battery. There are times when you are worried about troubles such as erasing. In that case, a mechanical counter can be used, and the action and effect in that case are the same as those of the present embodiment.

Next, a second embodiment based on claim 2 will be described with reference to FIGS. 2 and 3. The description of the same parts as those in the first embodiment will be omitted.

FIG. 2 is a system diagram of the variable displacement air compressor of this embodiment. The rotation speed command value, which is the output of the control device 5, is input to the inverter 4 and branched at the same time.
Entered in. Here, the rotation speed command value is digital
Although treated as data, it may be analog data such as a voltage value. The arithmetic unit 41 is the counter 24 in the first embodiment.
It has a timekeeping function and a calculation function. Arithmetic unit 4
The output information of 1 is input to the determination device 25 as the total number of rotations of the rotor. The computing unit 41 and the determination device 25 are integrated microcomputers as hardware, and the functions may be shared by software. Alternatively, the control device 5 may be added to be integrated.

The operation of the variable speed compressor of this embodiment is as follows.
Although it is the same as the first embodiment shown in FIG. 1, the method of detecting the total number of revolutions is different.

The detection method is such that the total number of rotations of the rotor is
It utilizes the principle that the rotational speed of the rotor is integrated by time. According to the principle, a rotation speed sensor is provided instead of the rotation sensor, and the total rotation speed can be obtained by integrating the output thereof. In this embodiment, the speed command value output from the control device 5 is used instead of the rotation speed. The rotation speed command value is not the rotation speed itself, but the latter follows the former and has the same value during steady operation, but deviates due to a slight time delay during acceleration or deceleration. However, the error is small, and the sign of the error is reversed during acceleration and deceleration,
Since they cancel each other out, there will be no gross error. Therefore, there is no problem in using the rotation speed command value instead of the rotation speed.

FIG. 3 is a graph of the rotational speed 52 and the total rotational speed 53, which change with the passage of time 51 in the embodiment shown in FIG. As shown in FIG. 3, the rotation speed 52 of the rotor changes as a graph 54 with the lapse of time. The calculator 41 reads the rotation speed command value as the rotation speed at constant time intervals ΔT55. The value at that time is indicated by the white circle 5 in Fig. 3.
Shown by 6. The calculator 41 adds the product of the rotational speed 54 and the elapsed time 55 to the total rotational speed 53 up to now. Since this operation is repeated at the constant time interval ΔT55, the total rotation speed becomes the graph 57 which sequentially increases.

The quantization error due to the finite calculation time interval ΔT55 will be described. If the time interval ΔT55 is infinitely small, the total number of revolutions obtained will be a true integral value, but since it is difficult to realize it, it will be a finite value and will include a quantization error. However, since a certain degree of error is allowed in the total number of revolutions, if the time interval ΔT55 is a sufficiently short time interval, there is no practical problem with this error.

At time T58, the judgment device 25 judges that the total number of revolutions 57 has exceeded the threshold value N revolutions 59, and instructs the display device 26 to display.

According to this embodiment, since the signal of the rotation speed instruction value is directly used, the detecting means may be only the signal line. Therefore, an inexpensive and simple display system can be realized without requiring an expensive sensor for detecting the total number of rotations or the rotation speed.

Next, a third embodiment based on claim 4 will be described with reference to FIGS. The description of the parts common to the first and second embodiments will be omitted.

FIG. 4 is a system diagram of the variable displacement air compressor of this embodiment. The configuration of the present embodiment is obtained by adding the storage device 61 and the output device 62 to the configuration of the second embodiment and enhancing the functions of the determination device 25 and the display device 26. Storage device 61
Has a built-in clock function, has a function of using the rotation speed command value as input data, storing the time change thereof, and outputting the stored content in response to an external request. The output device 62 is a small printer, and has a function of printing out the stored contents in the storage device 61 as needed or according to a user's instruction.

FIG. 5 shows a display example of the display device 26 of this embodiment. The display device 26 is composed of a liquid crystal display, a control circuit for driving the liquid crystal display, and a storage circuit for storing the contents to be displayed, and has a function of displaying the characters and illustrations on the surface by adding the input information to the stored contents. In addition, the display device 2
The surface of 6 has a touch panel function, and also has a function of inputting a user's instruction and sending a signal to the control device 5, the determination device 25, and the output device 62.

The basic operation of the variable displacement compressor of this embodiment is the same as that of the second embodiment shown in FIG. An example of the contents of the display device during operation will be described with reference to FIG.

On the display panel 71 on the surface of the display device 26, the set pressure determined by the user is shown by a bar graph 72 with only a frame and a numerical value 73, and the discharge pressure controlled with the aim of matching the value is shown. It is displayed as a bar graph 74 overlaid on the set pressure graph 72. The discharge pressure 74 is the output of the pressure sensor 11. Therefore, it can be seen at a glance whether the target pressure is achieved or how much the target pressure deviates.

The ratio of the current discharge amount to the total discharge capacity, which is the load ratio of the compressor, is displayed on the graph 75. Since this value is equal to the ratio of the current rotation speed to the maximum rotation speed, it is calculated by multiplying the rotation speed instruction value by a constant.

The display panel 71 is also used as an input device, and a pressure increasing button 77 and a pressure reducing button 78 are displayed on the panel. By touching this with a finger, the instruction is transmitted to the control device 5. The display contents of the display panel 71 are switched by pressing the display changeover switch 27. Each time, the meanings and functions of the buttons on the displayed panel also differ. Therefore, since many switches are integrated on the display panel 71, the number of ordinary switches and buttons is reduced, and the compressor is a simple operation panel.

In this embodiment, similarly to the second embodiment, the inspection time is judged by the judging device 25 by the operation of the compressor. As a result, a message 79 "needs to be inspected" is displayed on the display panel 71 to inform that the inspection is required. The message 79 blinks to call the user's attention. Also,
When the inspection is completed, the message is reset by resetting.
The message 79 disappears, the contents stored in the computer 41 are updated, and the contents are reset so as to notify the next inspection time.

When the user gives an output instruction to the output device 62 of the display switch on the display panel 71, the information stored in the storage device 61 is sent to the output device 62 and printed. An example of the print result will be described with reference to FIG.

A time axis 81 and a load ratio axis 82 are printed on the recording paper 80 in advance. Since the recording paper 80 printed by the output device 62 is sent to the right, the left side has newer information. The load ratio graph 83 and the operation start date and time 84 are printed on the recording paper. The load ratio graph 83 is a time change of the load ratio 75 in FIG. 5, and is interrupted when the compressor is stopped and the power is cut off. As the operation start date and time 84, the date and time when the operation is started are read out from the clock function, and are recorded first, and then the load ratio 83 is recorded.

By observing this output result, it is possible to know how much the capacity of the compressor is used and how much the load changes.

Although a small printer is used as the output device 62 in this embodiment, an interface with a storage medium such as a memory card or a communication line may be used. By doing so, it becomes possible to collect usage records of a plurality of compressors and process the stored contents by a computer, apart from the installation location of the compressor 1.

[0050]

According to the present invention, in a compressor in which the rotor rotation speed changes according to the load in order to maintain the discharge pressure at a constant value, the inspection time and the replacement time of consumable parts are clearly indicated. It is possible to realize a variable capacity compressor that is highly reliable and easy to use.

[Brief description of drawings]

FIG. 1 is a system diagram of a first embodiment.

FIG. 2 is a system diagram of a second embodiment.

FIG. 3 is a graph showing the relationship between the rotation speed and the total rotation speed of the second embodiment.

FIG. 4 is a system diagram of a third embodiment.

FIG. 5 is an example of a display device according to a third embodiment.

FIG. 6 is an example of an output result of the third embodiment.

[Explanation of symbols]

1 ... Compressor, 2 ... Compressor main body, 3 ... Electric motor, 4 ... Inverter, 5 ... Control circuit, 6 ... Commercial AC power, 7 ... Air cleaner, 8 ... Intake port, 9 ... Discharge port, 10 ... Discharge pipe, 1
1 ... Pressure sensor, 12 ... Power shaft, 21 ... Sensor, 22 ...
Reflection tape, 23 ... Sensor amplifier, 24 ... Counter, 25
... Judgment device, 26 ... Display device, 27 ... Display changeover switch, 31 ... Temperature sensor, 32 ... Converter, 33 ... Clock, 4
1 ... Arithmetic unit, 51 ... Time axis, 52 ... Rotation speed axis, 53 ...
Total rotation speed axis, 54 ... Rotation speed graph, 55 ... Constant time interval ΔT, 56 ... Rotation speed reading value, 57 ... Total rotation speed graph, 58 ... Time T, 59 ... Threshold N rotations, 61
... storage device, 62 ... output device, 71 ... display panel, 72
... Set pressure graph, 73 ... Set pressure value, 74 ... Discharge pressure value, 75 ... Load ratio graph, 77 ... Pressure increase button, 78 ... Depressurize button, 79 ... Message, 80 ... Record paper, 81 ... Time axis, 82 ... Load ratio axis, 83 ... Load ratio graph, 84 ... Operation start date and time.

Claims (5)

[Claims] 1. A roller while keeping the discharge pressure substantially constant.
In a variable displacement compressor having a function of varying the discharge amount of the compressed gas per unit time by changing the rotation speed of the rotor, the total rotation number of the rotor is detected, and the value detected by the detection unit is A storage means and a determination means for determining whether or not a message to the user is to be clearly displayed by comparing the stored content stored in the storage means with a preset criterion as one of the criteria. A variable capacity compressor, comprising: a display means for displaying a message to the user. 2. The rotation speed command value, which is output information of a controller for instructing the rotation speed or the rotation speed of the rotor, as means for detecting the total rotation speed of the rotor. A variable displacement compressor characterized by comprising one detecting means, detecting the value at a predetermined time interval, and integrating the detected value over time to obtain the total number of revolutions. 3. The variable capacity type display device according to claim 1 or 2, wherein the content displayed to the user is the time when inspection is required or the time when replacement of consumable parts is required. Compressor. 4. The rotor rotation speed detected at a predetermined time interval or a rotation speed command value proportional thereto in addition to the total rotation speed of the rotor according to claim 2, and the detected time is stored. A variable capacity compressor, comprising: a storage unit for storing the stored contents, and an output unit for outputting the stored contents as necessary. 5. The compressor according to claim 1, wherein the compressor is a screw type air compressor having a screw rotor rotated by an induction motor which receives electric power of variable frequency from an inverter. Variable capacity compressor.