JPS61197957A - Air conditioner using screw 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 Application of the Invention] The present invention relates to a partial load operation method of an air conditioner using a multi-screw pressure control, and particularly to an efficient power saving method during partial load operation. This invention relates to a suitable control method that enables operation.

[Background of the invention]

Air conditioners with stepless control or continuous control functions using conventional mold-closing screw compressors are capable of operating in all part-load operating ranges (usually Vi100 to 25 %) to perform stepless control operation, the drawback was that the operating efficiency of the air conditioner, that is, the refrigeration effect per unit input, deteriorated, especially in the 25 to 50% partial load operation band at light loads. there were. In Figure 3, the horizontal axis shows the compressor @child side ratio (=cooling capacity ratio), and the vertical axis shows the reduction ratio.
Take the R power change rate and set each value at full load operation to 100%.
It is a characteristic diagram shown as a percentage. Here, it is shown that the efficiency of the air conditioner during each partial load operation is better if there is a curve below a straight line drawn diagonally upward at 45 degrees to the right. In other words, if the air conditioner is used as much as possible in the area where (power consumption change rate) / (cooling capacity ratio) It turns out.

RI] Figure 3 rL+0 [J ~ 25% (or 33%)
Since the air conditioner is operated at partial load up to 50% to 25% (or 33%), it can be seen that the usage is inefficient, and when the load is 25% or more, the air conditioner "stops" r2
Perform 0N10FF' operation at 5% 0-de.

In addition, as an improvement measure for the above method,
5 is proposed as 4fIE. This method is as shown in Fig. 4, when the pressure shaft machine (1) is started, the starting load t@ of the vcH stealth machine is
Perform partial load operation at about 25% to stabilize the load, then 10%
Perform each chest opening operation continuously in the range of 0% to 50%, 100%
% to 50% continuous capacity side - curves & are all below the 45° straight line, making it an efficient usage.
Air conditioning *rxr stops when load is less than 50%", "50
% load, and when the load fluctuates around 50%, the air conditioner frequently operates at 0N10FFH degrees, leading to problems such as a decrease in service life.

[Purpose of the invention]

The present invention was invented in view of the above, and it enables a 9-volume controlled operation depending on the load, improves the efficiency in capacity-based operation, and extends the lifespan of each device that makes up the refrigeration cycle. [Summary of the Invention] In order to achieve the above object, the present invention provides a partial load operation of 25 to 33% at the start of the screw pressure motion, and then a In order to improve followability, 50% partial load operation is forcibly performed for a certain period of time, and then continuous thoracotomy operation is performed using 50% partial load as the starting point. By adopting such a partial load operation configuration, it is possible to eliminate areas with poor operating efficiency (
50 to 25 or 33%) is less frequent, efficiency is improved during load control operation, and 2.0% during steady operation.
It enables continuous capacity limited operation in the range of 5 to 100%, and has a percentage characteristic that allows operation commensurate with the load.

[Funny example of invention]

Hereinafter, one embodiment of the present invention will be explained with reference to the drawings.

Figure 1 is a diagram of the control mechanism of a closed screw pressure machine. show. A pair of male and female screw rotors 1 are directly connected to a rotor shaft 2 (not shown) by a rotor shaft 2. The suction gas refrigerant a is sucked into the left side of the rotor, and as the rotor mesh advances to the right, it is moved under pressure, and when it reaches a certain pressure ratio r, it is released to the discharge port on the right end face and is discharged as a hot, high-pressure gas.

A slide valve 3 disposed on the upper surface of the pair of rotors 1 controls the capacity by adjusting the timing of the suction gas trapping position of the rotor 1. That is, the slide valve 3 moves in the direction of the arrow 4, and when it is moved all the way to the left, it becomes 100% load operation, and when it is moved all the way to the right, it is at the minimum load (usually 25~25%).
33%) Driving. The slide valve 3 is connected by a rod 5 to a piston 7 in a cylinder 6, and in the case of continuous displacement control, when hydraulic pressure is applied to the left chamber of the piston 7, the slide valve 3 moves to the right, and part load is applied. Driving (rotation down). Conversely, when rotting up, drain the oil in the left chamber of the piston 7 and move the slide valve to the left. The right side of the piston 7 is connected to the low pressure side of the refrigeration cycle through a conduit 8, and is connected to the low pressure side.

Also, the oil supply to the left violet of the piston 7 is carried out using the 'wL magnetic valves 9 and 10.
The circuit is opened to discharge oil from the cylinder pressure side oil sump (not shown), and conversely, the solenoid valve 11 is opened to discharge oil from the low pressure side VC of one refrigeration cycle. The illustrated piston position shows a 50% load position, and at this time, the left chamber of the piston 7 is maintained at a positive pressure and a low pressure. In this case, a pressure switch 12 connected to the upper surface of the cylinder 6 by a conduit is applied with a positive pressure, and a pressure switch 13 is applied with a low pressure. Each pressure switch has a switching mechanism that operates at an intermediate pressure between the expansion pressure and the low pressure normally used in the refrigeration cycle, and the pressure switch 12 detects whether the pressure am capacity control rate exceeds 50%. can do. Further, the pressure switch 13 is connected to a position where high pressure is applied when the slide valve reaches the 25% tentacle unloading position and the minimum unloading operation state can be used.

The spring 14 is compressed in the illustrated state, but when the compressor stops, the electromagnetic valve 9 for oil supply at stop is opened to supply oil to the piezoelectricity of the piston 7, and the spring force of the spring 14 causes the piston 7t'' to open. Slide valve 3 all the way to the right side.
is set to the minimum unload position and waits for the role of keeping the VC on standby so that the minimum unload can be started at the next compressor start. Further, by opening the drain oil solenoid valve 15 connected to the pressure switch 12 through a ring pipe, the drain oil from the five chambers of the piston 7 can be discharged to the low pressure side of the refrigeration cycle.

In the compressor capacity control mechanism configured as described above, the following operations are performed on the refrigeration cycle.

At the time of starting, the slide valve performs minimum capacity control operation using the spring 14 and the oil supply solenoid valve 9, and the @#c of the starting load of the motor is controlled.
Measure. After that, for a certain period of time (5 to 10 minutes), the oil supply % magnetic valve 9 is opened and the oil drain tttm valve 15 is opened to maintain a 50% partial load operation state, and the refrigeration cycle components follow up. It's an impersonation of gender.

The capacity control range for stepless P' in the next rt continuous operation is to drain or refuel the power supply for a fixed period of time (usually 2 to 60 seconds) shorter than the period at fixed time intervals (usually 0.5 to 5 minutes). valve(
11 or 10[--open the circuit and move the slide valve 3 to an arbitrary position, and perform each continuous i control 1 operation commensurate with the load.

Figure 2 shows the example based on the above! ? '=lJ The load characteristic diagram during operation is shown, and the horizontal axis shows the compressor capacity, the sub-total ratio, and the vertical axis shows the rate of change in power consumption, as in Figure 3.4. The efficiency of the receiver during each partial load operation indicates that the further the curve fits below the straight line drawn at 45° on the curve, the better the efficiency. The solid line indicates the continuous capacity control range, and the dotted line indicates the capacity control range at the time of starting. The range of continuous control from Takeshi is 100 to 25 (or 33)%, same as the conventional Figure 3.
However, at startup, the VC is started with strict capacity control (25-33% load), the starting torque of the 'dim machine is reduced @, and then forced to operate at 50% partial load. By performing legal control starting from full load and then 50% partial load, frequent operation in areas with poor operational efficiency is reduced. However, unlike the conventional usage shown in Figure 2, it can be seen that the frequency of empty v@noodles is completely reduced to 0N10F', and the usage life is prevented from decreasing.

〔Effect of the invention〕

As described above, according to the present invention, by adding a pressure switch and a solenoid valve for detecting the 50% unloading position to the structure of the conventional stepless capacity control mechanism of a screw compressor, Capacity control band a
1. Operation between 100% and 25% with good characteristics can be performed. In addition, conventional methods "stop" even when the load is around 50%.
The 0N10FF operation charge was ``50%'', but when starting the lifting platform of the present invention, after performing the minimum capacity control operation, the 50% partial load operation was forced, and then the 10% load operation was forced.
By shifting to continuous capacity control operation of 0 to 25 (or 33)%, operation in inefficient areas can be avoided as much as possible, and the followability of the refrigeration cycle equipment can be improved and the 0N10FF frequency can be reduced. It is possible to reduce this and prevent a decrease in service life.

[Brief explanation of drawings]

Fig. 1 is a diagram of the displacement of the capacity control mechanism 1 of a screw compressor showing an embodiment of the present invention, Fig. 2 is a partial load characteristic diagram of the embodiment of Fig. 1, Figs. FIG. 2 is a partial load characteristic diagram of a conventional screw compressor. 1... Rotor 2... Rotor shaft 3... Slide valve 4... Arrow 5 indicating the operating direction of the slide valve
...Rod 6...Cylinder 7...Piston 8...Conduit 9...For oil supply when stopping and starting'
vIL magnetic valve 10...Solenoid valve for oil supply 11...'wL calm valve for oil drain 12...Pressure switch for 50% load detection 13...259!60-Pressure switch for detection of load 14
... Spring 15 ... Solenoid valve for draining oil. ingredient

Claims (1)

[Claims] In a refrigeration cycle in which a screw compressor with a capacity control leg, a heat exchanger on the user side, a pressure reducing device, and a heat exchanger on the heat source side are connected in sequence through piping, the screw compressor drives a slide valve hydraulically. A capacity control mechanism;
The minimum capacity control ratio has a partial load operation stage of approximately 25 to 33% and a partial load operation stage of 50%, and when starting the refrigeration cycle, the compressor is started in the partial load operation stage of the minimum capacity. Then, after operating at a 50% partial load operation stage, it shifts to continuous capacity control operation, and during normal operation, capacity control operation is performed in the range of 100 to 25 (or 33)% according to load fluctuations. An air conditioner using a screw compressor characterized by: