JP2555084Y2 - Protection circuit of hermetic electric compressor - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protection circuit for a hermetic electric compressor, and more particularly to prevention of stagnation start.

[0002]

2. Description of the Related Art FIG.
FIG. 1 is a circuit diagram showing a protection circuit of a conventional hermetic electric compressor disclosed in Japanese Patent Application Laid-Open Publication No. H10-207, in which 1 is a hermetic electric compressor for compressing a refrigerant, and 2 is a power supply to the hermetic electric compressor 1. Contactor, 2a is an exciting coil, 2b is a contact, 3 is a self-holding circuit, which comprises an exciting coil 3a, a normally open (positive) contact 3b, and a normal cross (negative) contact 3c. Reference numeral 4 denotes an overcurrent relay, which comprises excitation coils 4a and 4b and contacts 4c and 4d.
The exciting coils 4a and 4b are connected in series between the U and W phases of the three-phase AC power source, and the contacts 4c and 4d are connected to one end of the exciting coil 2a in the electromagnetic contactor 2 and the three-phase AC power source via the intermediate line 4e. It is connected in series with the U phase.

Next, the operation will be described. When an abnormal load is applied to the hermetic electric compressor 1, the three-phase power supply U, V, W
Current of each phase increases. Here, when the current of each phase increases, the attracting force increases with the increase in the current flowing through the exciting coils 4a, 4b of the overcurrent relay, so that the contacts 4c, 4d are opened. As a result, since the exciting coil 2a of the electromagnetic contactor loses the attractive force, the contact 2b is pushed up by the spring force to be in an open state, and the supply of the three-phase AC power to the hermetic electric compressor 1 is cut off. The abnormal temperature rise and breakage of the electric motor 1a at the time of abnormal load are prevented. Further, if the hermetic electric compressor 1 is opened in a state where one phase of the three-phase power supply is disconnected, a large current flows through the remaining two phases, so that the exciting coils 4a, 4b of the overcurrent relays In the case of any one of the above, or when the phase of the V phase is lost, the attractive force of both the exciting coils 4a and 4b increases, and the electromagnetic contactor 2 is opened, so that the burnout of the electric motor 1a due to the start of the phase loss is prevented. Will be.

FIG. 6 is a refrigerant circuit diagram of a conventional air conditioner disclosed in Japanese Patent Publication No. 3-50958. The oil separator 7 provided on the discharge side of the hermetic electric compressor 1 is provided with a solenoid valve. 8 through an oil return bypass path 9 to an accumulator 10
When the hermetic electric compressor 1 is stopped or started, the solenoid valve is opened and oil is returned from the accumulator 10 to the hermetic electric compressor 1.

[0005]

The protection circuit of the conventional hermetic electric compressor is configured as described above, and the protection circuit against the pumping pressure (rapid pressure fluctuation) due to the liquid compression generated at the time of stagnation start-up is provided. Since the current does not increase so much and the protection circuit does not operate, there have been problems such as shaft seizure due to abnormal load due to the pumping pressure, increase in power consumption, and generation of abnormal noise.

The present invention has been made in order to solve the above-mentioned problems, and there is provided a hermetic electric compressor capable of preventing bearing seizure, increase in power consumption, and occurrence of abnormal noise due to pumping pressure at the time of stagnation start. The purpose is to obtain a protection circuit.

[0007]

The protection circuit of the hermetic electric compressor according to the present invention has an NTC thermistor embedded in an electric motor, and connects the NTC thermistor and an exciting coil of an electromagnetic contactor in series. And a heater connected in parallel to the primary side of the excitation coil of the electromagnetic contactor.

[0008]

The protection circuit of the hermetic electric compressor according to the present invention has an NTC thermistor embedded in the electric motor.
By connecting the thermistor and the exciting coil of the electromagnetic contactor in series and connecting the heater in parallel with the primary side of the NTC thermistor and the exciting coil of the electromagnetic contactor, the temperature inside the hermetic electric compressor can be reduced. When detected by the NTC thermistor, when the temperature is low, current does not flow to the exciting coil of the electromagnetic contactor, but current flows only to the heater, and when the temperature rises, the current flows to the exciting coil of the electromagnetic contactor.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. In the figure, reference numeral 5 denotes an NTC thermistor built in the hermetic compressor 1, and its characteristic is that if the temperature of the thermistor is t ₁ ° C. or higher, the resistance value is large and the ratio is R ₁ / R as shown in FIG. ₂ > 1000 characteristics.
Reference numeral 6 denotes a heater of the hermetic electric compressor 1, the resistance value R _{H of which} is slightly larger than the resistance value R ₂ of the NTC thermistor 5. The exciting coil 2a of the electromagnetic corrosion apparatus is connected in series with the NTC thermistor 5, and the heater 6 is connected in parallel to the primary side of the NTC thermistor 5 and the exciting coil 2a of the electromagnetic contactor.

Next, the operation will be described with reference to the flowchart of FIG. 3 showing the control operation of the protection circuit of the hermetic electric compressor. In step 11, a start command of the hermetic electric compressor 1 is issued. In step 12, the internal temperature of the hermetic electric compressor 1 is determined by the NTC thermistor 5, and if it is equal to or higher than t ₁ ° C., the process proceeds to step 15 where the hermetic electric compressor 1 is started. Further, if the internal temperature t ₁ ° C. or less, is energized to the heater 6 moves to step 13, it is determined whether the internal temperature t ₁ ° C. or more in step 14, if the internal temperature t ₁ ° C. or more, in step 15 The transfer hermetic electric compressor 1 is started.

In the above embodiment, a three-phase power supply is used as a power supply. However, a single-phase power supply may be used as a power supply, and the same effects as in the above embodiment can be obtained.

[0012]

[Effect of the invention] As described above, according to the invention, the NTC
The NTC thermistor is embedded in the electric motor, and the NTC thermistor and the exciting coil of the electromagnetic contactor are connected in series.
By connecting a heater in parallel to the next side, the temperature inside the hermetic electric compressor is detected by the NTC thermistor. When the temperature is low, current does not flow to the exciting coil of the electromagnetic contactor, but current flows only to the heater. When the temperature rises, it flows to the excitation coil of the electromagnetic contactor, so that it is possible to obtain an effect that can prevent bearing seizure, increase in power consumption, and occurrence of abnormal noise due to pumping pressure at the time of stagnation start. is there.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a protection circuit of a hermetic electric compressor according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing characteristics of an NTC thermistor and a heater of FIG. 1;

FIG. 3 is a flowchart showing a control operation of the protection circuit of the hermetic electric compressor of the present invention.

FIG. 4 is a configuration diagram showing a protection circuit of the hermetic electric compressor according to one embodiment of the present invention.

FIG. 5 is a circuit diagram showing a protection circuit of a conventional hermetic electric compressor.

FIG. 6 is a refrigerant circuit diagram of another conventional air conditioner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hermetic electric compressor 1a Motor 2 Electromagnetic contactor 2a Excitation coil 5 NTC thermistor 6 Heater

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-70050 (JP, A) Actually open Showa 53-82810 (JP, U) Actually open Showa 54-163055 (JP, U) Actually open Showa 63- 143778 (JP, U)

Claims (1)

(57) [Scope of request for utility model registration] 1. A hermetic electric compressor for compressing a refrigerant, an electromagnetic contactor for controlling power supply to the hermetic electric compressor,
In a hermetic electric compressor having a heater for heating the hermetic electric compressor, an NTC thermistor is embedded in the electric motor, and the NTC thermistor and an exciting coil of an electromagnetic contactor are connected in series. A protection circuit for a hermetically sealed electric compressor, wherein a heater is connected in parallel with a primary side of an exciting coil of a contactor.