JPS6273058A - Refrigerator - 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 (a) Field of Industrial Application The present invention relates to a refrigeration system equipped with a compressor that can change the rotational speed of an electric motor depending on the refrigeration load.

(Example 1) Conventional technology Conventionally, in an air conditioner in which an electric motor and a compressor driven by the electric motor are housed in a sealed container, and this sealed container is connected to a refrigerant pipe to form part of the refrigeration cycle, the rotational speed of the electric motor is There is a system disclosed in Japanese Patent Publication No. 12532/1983 that can be changed according to the air conditioning load.

The content of this is that the greater the air conditioning load (difference between indoor temperature and set temperature), the faster the rotational speed of the electric motor is to increase the refrigerating capacity.

(/Sai) Problems to be Solved by the Invention In this way, as the air conditioning load increases, the rotation speed of the motor increases. There was a risk that the oil inside the compressor would deteriorate due to a rise in the temperature of the refrigerant.

The present invention aims to prevent poor insulation of motor windings and deterioration of oil that occur when the temperature of refrigerant discharged from a compressor becomes high.

(b) Means for Solving the Problems In order to achieve this object, the refrigeration system of the present invention allows the rotational speed of the electric motor that drives the compressor to be changed in accordance with the refrigeration load, and This system detects a rise in the temperature of the refrigerant in the machine and lowers the rotational speed of the motor when the temperature of the motor windings becomes higher than a set value.

(E) Function The refrigeration system of the present invention uses a detector to detect the temperature of the refrigerant on the discharge side of the compressor, and the temperature of this refrigerant increases, causing poor insulation of the motor windings and deterioration of the oil. When this occurs, the rotational speed of the motor is lowered to lower the temperature of the motor windings as well as the temperature of the refrigerant.

(F) Example In Fig. 1, (1) is a separate air conditioner, which is composed of an indoor unit (2), an outdoor unit (BL), and inter-unit piping (2) that connects both units. The indoor unit has a built-in indoor heat exchanger (3) that acts as an evaporator during cooling operation and as a condenser during heating operation.

On the other hand, outdoor unit) (Bl includes a refrigerant compression device (4), a four-way valve (5), an outdoor heat exchanger (6) that acts as a condenser during cooling operation and an evaporator during heating operation, and a pressure reduction device. (7), strainer (8), and muffler (9)
is built-in.

As shown in FIG. 2, the compression device (4) includes an electric motor Q11 and a compressor a3 built into a closed container 00). (1
3) is the space (14) between the electric motor α1) and the compressor α2
This is a temperature sensing element disposed in the compressor α2 to detect the temperature of the refrigerant discharged from the compressor α2. The refrigerant discharged from the compressor (121) passes through the gap (1η) between the rotor α9 and the stator (1b) of the electric motor 01, is guided upward into the closed container αQ, and is discharged from the discharge pipe 08. At this time, the windings of the electric motor α1) are cooled by the refrigerant. Then, during cooling operation, for example, the power frequency is varied from 30Hz to 85Hz and the rotational speed of the electric motor (11) is changed to increase the refrigeration capacity to 132Hz.
It can be varied from 0 m/h to 2750 m/h.

Furthermore, the refrigeration capacity can be varied from 135 am/h to 410 om/h by inputting from a frequency output power supply device that can vary the power frequency from 30 Hz to 125 Hz during heating operation.

The following components are connected to the pressure reducing device (7). (19 is a parallel circuit in which the first pressure reducing element (2) and the on-off valve 01) are connected in parallel. This on-off valve 0]) is opened when the frequency input to the compression device (4) becomes 50 Hz or higher (during high load) during cooling operation and heating operation. Then, refrigerant is caused to flow into the first pressure reducing element (2) during low load during heating operation (when the frequency input to the compression device (4) becomes 50 Hz or less).

■ is the second pressure reducing element connected in series with the parallel circuit α field,
Refrigerant flows during cooling and heating operations.

During cooling operation, the four-way valve (5) is set to the solid line state to allow the refrigerant to flow as shown by the solid line arrow in FIG. On the other hand, during heating operation, the four-way valve (5) is set to the broken line state. At this time, when the indoor air conditioning load is small and the frequency input to the electric motor (11) in 41 is controlled between 30Hz and 50Hz, the on-off valve c!1) is closed and the refrigerant is transferred to the direction indicated by the broken line arrow. Let it flow. or,
The electric motor (I) in the compressor (4) has a large indoor air conditioning load.
When the frequency input to ll is controlled between 50 and 125 Hz, the on-off valve (21) is opened and the refrigerant flowing out from the second pressure reducing element is transferred to the first pressure reducing element (201) as indicated by the dashed-dotted arrow. is bypassed and flows to the outdoor heat exchanger (6).

Compression bag when starting cooling or heating operation! The power frequency input to the electric motor (161 in ) is a flowchart showing the processing procedure of operation control.

In FIG. 3, when the air conditioner (1) starts operating, the room temperature (Tα) is measured and the set temperature (TI) is detected, and the difference (ΔT) between Tα and TI is determined. Next, one compressor is driven based on the power supply frequency (see the table above) corresponding to ΔT (steps 30 to 3).
5).

When the compressor (14) is driven in this way, the compressor Q21
Starts the 3-minute timer to keep the machine running for at least 3 minutes. After 3 minutes, the temperature sensing element (131) attached to the compressor (4) detects the temperature (Tc) of the refrigerant discharged from the compressor (1z).
A determination is made as to whether the temperature is above or below 6°C (step 36~
Step 37).

As a result of this determination, if the refrigerant temperature Tc is 126°C or higher, it is assumed that the winding of the motor α1) is higher than the set value, and the compressor C12 is stopped to prevent insulation failure in the winding of the motor α1). prevent. Three minutes after this stop, the process returns to step Gυ (steps 38 to 40). If the result of this determination is that Tc is 126°C or lower, the temperature (Tc) of the refrigerant is detected again after 3 minutes and it is determined whether this temperature Tc is 110°C or higher or lower (steps 41 to 43).

As a result of this determination, if the refrigerant temperature Tc is 110'C or higher, the frequency is lowered by 5 Hz than the current frequency input to the motor (Il+). The temperature is lowered. After that, this frequency increase is prohibited and the process proceeds to step Gυ (steps 44 to 45). As a result of this determination, the refrigerant temperature Tc is 110
If it is below 100°C, then it is determined whether the refrigerant temperature is above 100°C or below.

If the result of this determination is 100'C or more, the electric motor α1
) and step G, keeping the current frequency input in
Return to υ (step 46). If the temperature is below 100°C, a command is given to increase the frequency and the process returns to step (3) (step 47).

Figures 4 and 5 are diagrams showing the relationship between the refrigerant temperature and operating frequency of the compressor during cooling operation of this air conditioner and the temperature of the room being cooled by this air conditioner. indicates the state during normal operation, and the temperature of the refrigerant is approximately 1100C to 10
The operating frequency is determined so that the temperature is 0°C, so that the winding of the motor aυ does not rise above the set value. Figure 5 shows the state during overload operation, where the temperature of the refrigerant is 110°.
If it exceeds C, the operating frequency will be lowered. Also, if the temperature of the refrigerant exceeds 126°C even if the frequency is lowered by one level, stop the compressor. Then, after stopping the compressor,
Run the compressor again after a minute. In addition, since the air conditioning load has not decreased at this time, the operating frequency of the compressor is temporarily reduced to 8.
Although it becomes 5 FIz, it is lowered by 8011zK because the refrigerant temperature is 110°C or higher.

(G) Effects of the Invention As described above, according to the refrigeration system of the present invention, when the air conditioning load is large and the rotational speed of the motor is high and the temperature of the windings of this motor becomes higher than the set value, the motor The rotation speed is lowered.

Therefore, the amount of heat generated in the motor windings is reduced, and the occurrence of insulation defects in the windings can be prevented.

[Brief explanation of drawings]

The drawings show the refrigeration system of the present invention; Figure 1 is a refrigerant circuit diagram of the system, Figure 2 is a vertical sectional view of the compressor incorporated in the system, and Figure 3 is a process procedure of the system. Flow chart, Figure 4 is an explanatory diagram showing the relationship between indoor temperature, operating frequency, and refrigerant temperature during normal operation of the device, and Figure 5 is the same (explanatory diagram showing the relationship between indoor temperature, operating frequency, and refrigerant temperature during overload operation). It is an explanatory diagram showing the relationship. 14+... Compressor, 01)... Electric motor. ! l1il Figure 2 Figure 5 Figure 4

Claims (1)

[Claims] (1) In a refrigeration system in which an electric motor and a compressor driven by the electric motor are housed in an airtight container, and this airtight container is connected to a refrigerant pipe to form part of a refrigeration cycle, the rotational speed of the electric motor is adjusted according to the refrigeration load. 1. A refrigeration system characterized by comprising control means for lowering the rotational speed of the motor when the temperature of the windings of the motor becomes higher than a set value.