JPH03987A - Unit number control device for air compressor - Google Patents

Abstract

PURPOSE:To reduce the number of cables, simplify an installation work and make the work less expensive by providing a means for replacing each relay output with single analog output of 4 to 20 mA in the device wherein the number of units is controlled with the relay output of operation, stopping and unloading signals. CONSTITUTION:The air compressed with a plurality of air compressors 1 is collected into a manifold 2 and fed to an air reservoir 3 via a single pipe. In this case, each air compressor 1 is controlled with a unit number control device 8. Namely, the air from the air reservoir 3 is introduced to the pressure sensor 9 of the unit number control device 8 and pressure detected therewith is inputted to a microcomputer 14 via an A/D converter for executing the required arithmetic processing. Also, a control signal arithmetically processed is outputted via a D/A converter 11 and a voltage/current conversion output circuit 10. On the other hand, each air compressor 1 is provided with a signal discrimination circuit for converting and discriminating the outputted control signal into operation, stopping, unloading instructions or the like, and a discrimination circuit 6 for dividing the outputted signal into digital signals for actuating each relay.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for controlling the number of pneumatic compressors, a device for controlling the number of air compressors using an inverter, and a method for controlling the number of air compressors.

[Conventional technology]

Conventional unit control systems are systems that issue run, stop, and unload commands using the non-voltage output contacts of each relay, and also receive fault signals and operation answers as input from the compressor side using the non-voltage relay contacts. Met.

[Problem to be solved by the invention]

In the above-mentioned prior art, communication with the compressor starting panel was performed using relay contacts, and therefore signal lines for operation, stop, unload commands, failure, and operation answers were required for each compressor. For this reason, wiring work becomes extensive and expensive. Furthermore, when controlling the number of small-capacity compressors, the construction cost becomes relatively high compared to the energy-saving and labor-saving effects, and as a result, there is a problem in that the merits in terms of the number of compressors are reduced. The purpose of the present invention is to reduce the number of wiring lines, simplify the construction work, reduce construction costs, and provide an advantage in the number of units. [Means for solving the problem] In order to achieve the above object, the present invention provides a system in which commands to each compressor are transmitted through a single analog instead of a relay contact. The compressor is controlled by a signal discriminating device installed on the compressor side to determine whether the compressor is running, stopping, or unloading. In addition, the analog signal is output as a DC signal of 4 to 20m77 so as not to be affected by D disturbances such as noise, and is converted into voltage by a signal discrimination device installed on the compressor side. It is. Furthermore, since there is only one signal line,
Compressor failure determination uses pressure changes in the pressure sensor built into the unit control device, and detects the pressure change immediately after issuing a run or stop command, and uses the software in the device to determine a failure. be.

[Effect]

Run, stop, and unload commands to each compressor use analog signals of 4 to 20 mA, but stop is 4 m,
A% operation is determined to be 15 mA, and unloading is determined to be 20 mA. A signal discrimination device installed on the compressor side converts each signal into voltage and compares it with a set voltage to determine whether it is an operation command, a stop command, or an unload command. Based on this discrimination value, each non-voltage relay for operation, stop, and unload in the signal discriminator is operated, and the circuit of the starting board connected to this relay is operated to control the number of units. In addition, to determine if a compressor is malfunctioning, a pressure sensor is used to determine whether the pressure increases even slightly after issuing an operation command.If the pressure does not increase at all, it is assumed that the compressor that issued the operation command is malfunctioning. 14
The software for the number control device shall be assembled as shown in J. As a result, the number control device and the compressor can be connected with one signal line, so wiring can be simplified.

Furthermore, by using a current signal, it can be made more resistant to noise and disturbances, so it will not malfunction.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. The air compressed by the air compressor 1 is integrated with the air compressed by other air compressors in the collecting pipe 2, and is sent to the air tank 8 (1").
−/) Sent via piping. The air tank 8 is provided to absorb pressure fluctuations in the air used. The compressed air coming out of the air tank 3 is used as a power source for air tools and the like at the end of the line piping.

In the non-embodiment, a plurality of air compressors, which are air power sources, are controlled in number by an f device 8, and the number of operating units and anorod are controlled by appropriate operation, stop, and unload commands. The pressure is guided from the air tank 8 through air piping to a pressure sensor 9 built into the unit control device 8, and pressure fluctuations are detected and used for control. The pressure signal detected by pressure sensor f9 passes through a current/voltage conversion circuit within the sensor and is converted to an A/D.
The signal is sent to the i converter 12 and f'L is sent. The signal converted from analog to digital is calculated by the microcomputer 18, which is the central processing unit of 1fflJ Misaki, to determine and give commands for operation, floating, and unloading. Reference numeral 14 denotes a memory containing a D log 2 and various setting values to be controlled by the microcomputer 18. The run, stop, and unload signals commanded by the microcomputer 13 are digital, and are converted into one analog pressure signal by the D/A converter 11, and then converted to a single analog pressure signal by the voltage/current conversion output circuit.
It is converted into a current signal at O and outputted from the number-based control system +t8. A signal discrimination device 5 is installed on each compressor side to convert and discriminate the current signal output from the number control device 8 into run, stop, and unload commands, and a current signal discrimination circuit 6 drives each relay. into digital signals. This relay output is connected to the compressor starting panel 4 and is controlled to start, stop, and unload the compressor. The signal transmission form described above is installed and wired for each compressor whose number is to be controlled, and pressure control is performed by a plurality of compressors. Compressor failure 4IJ also explains how to determine a failure if pressure sensor f'9 does not detect a rise in pressure when an operation command is issued, and how to determine a failure by setting a relay to cut off the current output when a failure occurs. If the software of the microcomputer 13' is configured so that the detection of wire breakage is determined as the detection of a failure, the compressor 1 and the number control device 8 can be connected with one shielded wire of the Z core. Therefore, according to this embodiment, the six compressors can be connected with one shielded wire, which simplifies the wiring and has the effect of greatly reducing construction costs. FIG. 2 shows an example of how the current signal is used. When the current signal is 4 mA or less, the number control device 8 determines that the shield wire 7 is disconnected or the compressor 1 is malfunctioning. A current signal of 4 to 1OmA is a stop command, 1
The signal discrimination device 5 determines that the current signal of 010-15 is an operation command, and that the current signal of 15 to 20 mA is an unload command. The connection between the signal discrimination device 5 and the starting panel is delivered to the customer as an accessory of the number control device 8. Furthermore, as shown in Fig. 3, the compressor l driven by the inverter 15 can be driven directly with a current signal of 4 to 20 mA without the signal discriminator 5 by changing the software of the microcomputer 18 while leaving the hardware unchanged. , will be a big selling point for future inverter compressors.

〔Effect of the invention〕

According to the present invention, since one D wiring can be connected to each compressor, wiring work can be simplified and wiring work costs can be reduced.

Moreover, the advantage of controlling the number of units can also be set to an effective value. Furthermore, since the rotation speed command is sent directly to the compressor using an inverter, it has the effect of expanding the number of compressors.

[Brief explanation of the drawing]

FIG. 1 is a block diagram illustrating a system according to an embodiment of the present invention, and FIG. 2 is a diagram showing a setting method for determining a current signal.
FIG. 3 is a block diagram of the system used in the inverter compressor. 1... Compressor 2... Collection pipe 3... Air tank 4... Compressor starting panel 5... Signal discrimination device
6... Discrimination circuit 7... 2-core shielded wire 8.
...Number of units control device 9...Pressure sensor 10...
・Current output circuit 11...D/A converter 12・
・・A/D conversion FF 13 ・・Microcomputer 14
...Memory 15...Inverter. Old figure 1 Figure 2 Ship [ 5 I S negative shave 1; 7 Z 2 payments - 1 1 ° 4 ) t: Camphor silkworm 1314 con

Claims (1)

[Claims] 1. In an air compressor number control device that controls the number of air compressors by relay outputs of an operation signal, a stop signal, and an unload signal, means is provided for replacing each relay output with one analog output of 4 to 20 mA. A device for controlling the number of air compressors. 2. A device for controlling the number of air compressors according to claim 1, characterized in that the number of air compressors is controlled by providing a device on the compressor side for determining whether the current is 4 to 20 mA. 3. The air compressor number control device according to claim 1, further comprising means for directly driving the inverter.