JPH0545009A - Refrigerant compressor starting load control method - Google Patents

Abstract

(57) [Abstract] [Purpose] Damage or damage to compressor parts due to liquid compression that occurs when restarting under the condition that the refrigerant liquid stagnates in the compressor or the low-voltage system of the device while the refrigeration / air conditioning system is stopped. (EN) A method for controlling a load at start-up of a refrigerant compressor to avoid it. [Structure] Even after the compressor having a capacity control mechanism is started and accelerated at the minimum load possible, the minimum load operation is further continued for a predetermined time, and thereafter, a predetermined time is set for each appropriate capacity control step and sequentially. Control to increase the load. [Effect] Since the refrigerant suction force at the startup of the compressor is relaxed, the degree of liquid compression is reduced, and damage or damage to the compressor components and excessive current can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a start-up load control method for a refrigerant compressor for performing load control when starting a refrigerant compressor used in a refrigeration / air conditioning system or the like.

[0002]

2. Description of the Related Art Three-phase induction motor (hereinafter referred to as electric motor)
When starting a refrigerant compressor (hereinafter referred to as a compressor) driven by, the Y-Δ switching method of the electric motor is used. Figure 4
FIG. 5 is a characteristic diagram showing a load control pattern according to a conventional compressor load control method at startup, and FIG. 5 is a characteristic diagram showing a change in motor current at startup.

In FIG. 4, after the power is turned on, first, the electric motor is connected to the Y connection, and the load of the compressor is set to the minimum load (2 in the figure).
Start with 5% load). Then, after the electric motor is accelerated and the electric current of the electric motor in FIG. 5 is stabilized, the electric motor is switched to the Δ connection and the load of the compressor is controlled to be shifted to the full load.

[0004]

Since the conventional load control method at the time of starting the refrigerant compressor is performed as described above, the refrigerant liquid is supplied to the compressor or the low pressure system of the above-mentioned apparatus while the refrigeration / air conditioning system is stopped. When the engine is restarted in the state where it is laid down (the state where it remains), the Y connection (minimum load) is switched to the Δ connection (full load), and at the same time, a large amount of refrigerant liquid is sucked into the compression chamber of the compressor. For this reason, excessive liquid compression is performed, which causes damage or damage to the components of the compression element, and an excessive current also flows to the electric motor as shown in FIG. 5, which causes problems such as accelerated insulation deterioration of the electric motor winding. There was a point.

The present invention has been made in order to solve the above-mentioned problems, and a starting load control method for a refrigerant compressor capable of avoiding damage to parts of the compressor even under the severe conditions as described above. The purpose is to get.

[0006]

A method for controlling a load during start-up of a refrigerant compressor according to the present invention continues a minimum load operation for a predetermined time even after starting and accelerating with a compressor load as a minimum load, and thereafter in stages. The load is controlled to increase the load.

[0007]

According to the load control method of the refrigerant compressor of the present invention, the refrigerant suction force of the compressor at the time of starting is relaxed (gradual increase from the minimum value over time). Even if the engine is restarted under the condition that the residual amount remains, the refrigerant liquid is prevented from being rapidly sucked into the compressor.

[0008]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a characteristic diagram showing a load control pattern by a load control method at the time of starting the compressor in a refrigerating / air-conditioning apparatus equipped with a 4-cylinder reciprocating refrigerant compressor. In addition, FIG.
FIG. 4 is a characteristic diagram showing a change in electric motor current.

In FIG. 1, the compressor load in the Y connection process (T _Y time) is set to 25% load as in the conventional case, and 25% load is continued for t ₁ hours after the transition to Δ connection. afterwards,
The 50% load operation is performed for t ₂ hours, and finally the full load operation is controlled.

According to the above load control, the refrigerant suction force of the compressor increases gradually from the minimum value over time even after switching from the Y connection to the Δ connection. Moreover, even if the refrigerant remains in the low pressure system of the apparatus, the suction of the refrigerant liquid into the compression chamber of the compressor is alleviated.

At the same time, as shown in FIG. 2, the electric motor current also increases in accordance with the stepwise increase of the load, so that an excessive current does not flow.

Next, an embodiment of a load control circuit for performing the above load control will be described with reference to FIG. In FIG. 3, M is an electric motor, which is driven by a three-phase AC power supply of R, S, and T phases. MC1, MC2, MC3 are excitation parts of the electromagnetic switch, MC1 ₁ , MC2 ₁ , MC3 ₁ , MC1 ₂ , MC
2 ₂ is a switch of the electromagnetic switch, T1, T2, T3 are timers for which the times t _Y , t ₁ , t ₁ + t ₂ seconds of FIG. 1 are set, and T1 ₁ , T2 ₁ , T3 ₁ are timers T1, T2 T
2, T3 switches, SV1 and SV2 are capacity control solenoid valves of the compressor, and SW is a start switch.

Next, the operation will be described. When the switches MC1 ₁ and MC2 ₁ are ON and the switch MC3 ₁ is OFF, the electric motor M has a Y connection, and the switches MC1 ₁ and MC3
_{When 1} is ON and switch MC2 ₁ is OFF, Δ connection is established. Further, in the compressor, the capacity control solenoid valves SV1 and SV2 are O
FF is 25% load, SV1 is ON, SV2 is OFF, 5
0% load, 100% load when SV1 and SV2 are ON.

When the starting switch SW is turned on, first, the exciting portion MC2 is excited through the switch T1 ₁ , and the switches MC2 ₁ and MC2 ₂ are turned on. Therefore, the timer T
1 starts to operate, and the exciting part MC1 is excited,
The switches MC1 ₁ and MC1 ₂ are turned on. As a result, the electric motor M is Y-connected and started. At this time, since the switches T2 ₁ and T3 ₁ are OFF, the capacity control solenoid valve S
V1 and SV2 are OFF, and the engine is started at 25% load.

When t _Y seconds have passed, the timer T1 switches the switch T1 ₁ to release the excitation of the exciting portion MC2 and excite the exciting portion MC3. Also, the timer T2
T3 starts operating. Therefore, the switches MC2 ₁ , MC
2 ₂ becomes OFF, the switch MC3 ₁ is a ON, the motor M is switched to the Δ connection. After that, for t ₁ seconds, the operation is performed by the Δ connection at 25% load.

When t ₁ seconds have elapsed, the switch T2 ₁ is turned on by the timer T2 and the capacity control solenoid valve SV1 is turned on.
N, the compressor load shifts to 50%. Furthermore, t
When ₂ seconds have passed, the capacity control solenoid valve SV2 is switched T3 ₁ is turned ON by the timer T3 is turned ON, the compressor load is 100%.

[0017]

As described above, according to the present invention, the minimum load operation is further continued for a predetermined time even after the compressor is started and accelerated with the minimum load, and thereafter, the predetermined time is provided for each appropriate capacity control step. Since the load control is performed so that the load is sequentially increased, the degree of refrigerant liquid compression at the time of starting is reduced, damage to and damage to the compression element components can be prevented, and the excessive current of the electric motor can be prevented. It is possible to obtain effects such as prevention of occurrence.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing a load control pattern using a load control method for starting a refrigerant compressor according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a change in current of the electric motor according to the control method.

FIG. 3 is a configuration diagram showing an embodiment of a load control circuit for performing the same control method.

FIG. 4 is a characteristic diagram showing a load control pattern using a conventional load control method for starting a refrigerant compressor.

FIG. 5 is a characteristic diagram showing a change in current of the electric motor according to the control method.

[Explanation of symbols]

 M 3-phase induction motor

Claims (1)

[Claims] 1. At the time of starting a load controllable refrigerant compressor, the minimum load operation is continued for a predetermined time even after the motor is first accelerated to operate at a minimum load, and thereafter, a predetermined amount of load is applied every predetermined time. A load control method at the time of starting a refrigerant compressor, which performs load control so that the load is increased in steps.