JPS59231183A - Automatic control device for compressor - Google Patents

Abstract

PURPOSE:To reduce a shaft power and save energy by preventing over employing and cutting of the compressor by operating the number of unloading valve. CONSTITUTION:In case there is one valve under unloading and the pressure is in a stable area, a VL relay is put ON and a VLX, outputting the pulse commands of loading and unloading, is put ON when a load is increased and the pressure is reduced to a level lower than a set level. In this case, the valve in unloading, which is selected by a rotary circuit, is returned to loading. At this time, the relay VUO of an unload valve counter circuit is put ON and the time count of an effect waiting timer TVL for normal stop begins a time count. Upon the time-up of the timer TVL, a relay GLX for starting is put ON and one set of the compressor, being stopped, is started. According to such method, the over employing and cutting of the useless compressor may be prevented and the energy saving may be effected by operating the number of unloading valves.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention starts multiple compressors in a predetermined order.

This invention relates to an automatic control device that controls the air volume of the load without causing a shortage while stopping, loading, and unloading.

[Background of the invention]

Conventionally, as shown in Fig. 1, VL and VJ- (for loading and unloading the unloader valve, normal starting and stopping, H and GL for emergency starting and stopping,
A total of six GH pressure levels were provided for control. Therefore, if the difference between each pressure level is O = I K
y/cm2, the pressure difference between the required load pressure (minimum guaranteed pressure) NP and the control center pressure CP is 0.4.
There was also Kg/cm2. From this NP to CP'
! It is known that the shaft power of the compressor can be reduced by narrowing the pressure at the compressor, or in other words, by lowering the discharge pressure of the compressor.

If an attempt is made to narrow the pressure from NP to CP and the difference between each pressure level is narrowed, the following problems arise. If the pressure is above VH and below H, the compressor will control the discharge pressure in stages from 100 to 50 to 0, but the load will increase and the pressure will drop slightly below VL. Even if the compressor is stopped, there is a small pressure difference between VL and L, so there is a high possibility that one of the stopped compressors will be started even though there is a compressor on L with no load. From an energy saving perspective, this is also a waste. Despite the fact that there is a compressor that can be unloaded if the pressure rises, 1
This will cause the machine to stop.

[Purpose of the invention]

An object of the present invention is to provide an automatic control device for a compressor that brings the control center pressure closer to the minimum guaranteed pressure without overfilling or cutting the compressor, thereby achieving further energy saving effects.

[Summary of the invention]

The key point of the present invention is that by memorizing the state of the unloader pulp of the compressor, when the pressure decreases, it is confirmed that the unloader pulp of all compressors in operation is in the loaded state, and then
When the compressor is started, and conversely, the pressure is rising, the compressor is stopped after confirming that a predetermined number of unloader pulp has been taken up by the compressor in operation.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows the valley pressure levels when implementing the present invention. The difference between each pressure level is the same as the value used in FIG. Since L, which is the normal starting level, and H, which is the normal stopping level, are omitted, compared to the conventional method in FIG. 1, the difference between the minimum guaranteed pressure NP and the control center pressure CP is 0.1
This will result in a decrease in Kg/cm2. FIG. 3 is a specific example of the present invention. Here, in order to simplify the explanation, three compressor equipment having two unloader pulps will be explained.

GL that turns ON when the pressure is below the set level.

vL relay, GH and VH relays that turn on when the pressure is above the set level, and unloader pulp load/unload effect wait timer TPL.

Issue TPH and load/unload pulse commands”
rLX, VHX, pulse time setting timer TVU, and start/stop effect waiting timer TGL.

TVL, TGH, TVH, GLX, GHX that issues pulse commands for start and stop, timer TPU for pulse time setting,
Unload pulp count relay VUO, VUI, V
H2, VH3 and each 770-1' pulp load/unload command relay Vat.

■! ? ,...V3+, Vll, and unloader pulp (DMV+t, MVtz...MVs+
, MVsx. Here, a case will be described where two or more unloader pulps are unloaded and a stop command is output after the effect waiting time has elapsed.

Now, assuming that the pressure is greater than or equal to VH and less than GH, V
Since H is turned ON and TPH is normally in a time-up state, vHX is turned ON. Here, in the predetermined order, 0N-
First, the rotary circuit turns OFF' from Vll to O.
N), unloader pulp M V 1s is 0FFt,
, the compressor becomes 50-loaded. VHX is TVU
The self-hold is released when the time-up occurs. Furthermore, if the pressure is higher than or equal to VH and lower than GH, the effect waiting timer TPH operates in the same manner as described above after it times out.
VIS is turned ON, MVsa is Oii'PL, and the compressor is at 0 load.

Unload valve counter part relay VUO.

VUI, VH2, and VH3 are relays that turn ON when the number of 770-de valves is θ, 1, 2, and 3, respectively.

There are currently two pulps being unloaded, so relay V
When U2 is ON, effect waiting timer TV for normal stop.
H starts time counting.

When this TVH times out, the stop pulse relay GHX turns ON and stops one compressor.

Next, it is assumed that when there is one pulp being unloaded and the pressure is in a stable region, that is, between VH and VHO, the load increases and the pressure drops to between OL and VHO. Since the pressure has decreased, VL is turned ON, and since TPL is normally in a time-up state, VLX is turned ON. At this time, the selected unloaded valve is returned to the loaded state by the rotary circuit. At this point, relay VUO of the unload pulp counter circuit is 0.
N and υ, the effect waiting timer TVL for normal stop starts time counting. When this 'I'VL times out, the starting relay GLX is turned ON and one stopped compressor is started.

According to this embodiment, there is no need to set pressure levels for normal starting and stopping, and the control pressure of the unloaded pulp is used to start and stop.
It is also possible to perform a stop function.

Furthermore, application examples are shown in FIGS. 4 and 5.

Fig. 4 shows an arrangement in which the number of unload valves can be changed by a switching switch, and Fig. 5 shows an arrangement in which an effect wait timer can be selected depending on the number of unload valves.

〔Effect of the invention〕

According to the present invention, the control center value can be brought close to the minimum guaranteed pressure required by the load. In other words, the discharge pressure of the compressor is lowered, the shaft power is reduced, and an energy saving effect can be obtained. Also, by calculating the number of unload valves, unnecessary overfilling can be avoided.

It is possible to prevent overachievement.

[Brief explanation of the drawing]

Figure 1 is a diagram showing conventional control pressure levels, Figure 2 is a diagram showing conventional control pressure levels.
A diagram showing the control pressure level in the present invention, FIG. 3(a),
(b) is a circuit diagram of an embodiment of the present invention, FIGS. 4 and 5.
The figure is a circuit diagram of another embodiment of the invention. VUO, VUl, VU2. Vus...-Yo-Do valve number count relay, Vll-VS2...Unload 1st concave $2 Figure z/ $,, fj'' (c) 3rd circle (Jril 4th m 6th figure)

Claims (1)

[Claims] 1. Automatically starts and stops a plurality of compressors in a predetermined order within preset upper and lower pressure limits, and controls the number of compressors in operation without insufficient air volume required for the load. In the control device, means for always storing the state of the unloading valves, means for calculating the number of said valves being unloaded, and means for driving an effect wait timer depending on the number of said valves being unloaded. An automatic control device for a compressor, characterized in that it comprises means for starting and stopping the compressor provided at the control pressure level of the valve during unloading.