JPH0243036B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an overload protection device for a hermetic electric compressor.

[Conventional technology]

A conventional hermetic electric compressor will be explained with reference to FIG.

Reference numeral 1 denotes a cylindrical closed container, in which an electric motor 2 is placed above and a rotary compression element 3 is placed below.

A glass-sealed terminal 4 is attached to the airtight container 1, and the electric motor 2 and the glass-sealed terminal 4 are electrically connected via a lead wire 8.

Conventional hermetic electric compressor overload protection device 6
was attached to the outer surface of the closed container 1 as shown in FIG.

FIG. 2 is a longitudinal cross-sectional view of a conventional example showing an improved example of the hermetic electric compressor shown in FIG. .

[Problem to be solved by the invention]

In the conventional structure shown in FIG. 1 above, when the temperature of the electric motor 5 suddenly rises during overload operation of the compressor and the overload protection device 6 should be immediately activated to turn off the power, the Since the heat dissipation is large, the rapid temperature rise inside the compressor is not sufficiently transmitted to the overload protection device 6, which delays the timing of operation and causes the electric motor 5 to burn out.

Furthermore, in the conventional structure shown in Fig. 2,
The electric motor 5 responds very quickly to sudden temperature increases, but since the end coil 7 of the electric motor 5 becomes larger in size, it is necessary to increase the size of the hermetic electric compressor to ensure insulation distance. There was a problem in that the work of installing the overload protection device 6' on the overload protection device 6' to the motor vehicle 5 was complicated, and the work could not be streamlined.

The present invention solves the above conventional problems, and aims to operate an overload protection device according to the temperature rise of the electric motor during overload operation of the compressor without increasing the installation space. shall be.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a sealed container, a rotary compression element located within the sealed container, an electric motor for driving the compression element, a glass-sealed terminal attached to the sealed container, and a rotary compression element located within the sealed container. a cluster that is interposed between the glass-sealed terminal and the lead wire of the electric motor to connect the glass-sealed terminal and the lead wire; and a cluster that opens and closes an electric circuit to the electric motor according to temperature changes inside the compressor. The hermetic electric compressor is equipped with an overload protection device, and the overload protection device is located within the hermetic container and is integrated into the cluster.

[Effect]

The overload protection device is located inside the airtight container and is integrated into the cluster, so that when the overload protection device should be activated and the power should be turned off when the compressor is overloaded, Compared to a type that is attached to the outside surface of a sealed container, it is not affected by heat radiation from the container, and the heat generated by the motor is directly propagated through the refrigerant gas, so it operates in accordance with the temperature rise of the motor. do. Thereby, the overload protection device opens the electrical circuit to the motor when it should be switched off, so that the motor does not burn out.

〔Example〕

The present invention will be explained below with reference to embodiments shown in FIGS. 3 to 8. FIG. 3 is a longitudinal sectional view of the compressor according to the present invention, in which the glass-sealed terminal 4 of the hermetic container 1 and the lead wire 8 of the electric motor 5 are connected via a cluster 9, and the structure of the cluster 9 is as explained below. It was formed. In FIG. 3, the same reference numerals as in the conventional example indicate the same parts.

FIG. 4 shows the structure of the cluster 9 of the present invention, in which three pin insertion holes 12 are drilled in a thermosetting resin frame 10 at positions corresponding to the three pins of the glass-sealed terminal 4. It is being Pin insertion hole 12
A pin contact piece 11 made of a conductive metal plate is inserted inside. A cavity 15 is provided in a part of the resin frame 10, and a line break type overload protection device 16 is housed and fixed therein. That is, the fixed contact 17 is fixed to one end of the cavity 15,
A bimetal fulcrum 18 is fixed to the other end. A bimetal 20 having a movable contact 19 at one end is fixed to the bimetal fulcrum 18 . The fixed contact 17 and the movable contact 19 have a pin contact piece 11 and a lead wire contact piece 1 facing each other.
4. The fixed contact 17 and the bimetal fulcrum 18 are electrically connected as follows. That is, one of the three pin contact pieces 11 is connected to the overload protection device 16.
It is electrically connected to the fixed contact 17 of the contact piece 21a. The symbol of this pin contact piece is designated as u for the convenience of the following explanation. The remaining two pin contact pieces 11 are the two lead wire contact pieces 14 and the connecting piece 2.
It is electrically connected by 1b and 21c. Similarly, for convenience of explanation, the symbols of this pin contact piece are changed to v,
Let it be x. The remaining pair of lead wire contact pieces 14 and the bimetal fulcrum 18 of the overload protection device 16 are electrically connected by a connecting piece 21d.

The electrical wiring diagram of the hermetic electric compressor described above is shown in FIG. That is, a line break type overload protection device 16 is provided between the common connection point between the main coil and the auxiliary coil of the motor and the u terminal, and an operating capacitor 22 is installed outside the compressor between the v and x terminals. By connecting an AC single-phase power source between the uv terminals, it can be operated as a single-phase induction motor with a built-in overload protection device.

The propagation of heat generated by the motor 5 during overload in the above embodiment will be explained with reference to FIGS. 3 and 4. The refrigerant gas compressed and discharged from the compression element 3 is heated by exchanging heat with the electric motor 5 that fills the inside of the closed container and generates heat. Due to this heated refrigerant gas, the space within the closed container in which the cluster 9 is located becomes approximately at the same temperature as the electric motor 5. Here, if the compressor is in an overload operating state and the temperature of the electric motor 5 rises rapidly, the refrigerant gas in the closed container quickly reaches almost the same temperature as the electric motor 5 by exchanging heat with the electric motor 5 as described above. heated to. This heated refrigerant gas rapidly heats the bimetal 20 of the overload protection device 6 integrated into the cluster 9 to almost the temperature of the electric motor 5, so that the overload protection device 16 and the electric motor 5 are connected to each other through a space. However, when the temperature of the electric motor 5 rises, the contacts of the bimetal 20 are opened without a timing delay to cut off the electric motor 5 from the power supply, thereby preventing burnout of the electric motor 5. For example, according to experimental data, the temperature of the motor 5 during normal operation is 90°C, and 6 minutes after the load increases from normal operation to overload operation, the motor temperature rises by 30°C.
When the temperature reaches 120°C, the temperature of the overload protection device 16 incorporated in the cluster of this embodiment is almost the same as the temperature of the electric motor 5 both during normal operation and during overload operation. The temperature was the same (approximately 2°C lower) and increased with the same temperature gradient as the motor temperature from 90°C to 120°C. Therefore, the overload protection device 16 operates without delay in the temperature rise of the electric motor 5.
In contrast, the temperature of the overload protection device 6 attached to the outer surface of the conventional sealed container 1 is lower than that during normal operation.
At 75℃ (15℃ lower than the motor temperature of 90℃), 6 minutes after overload operation, the temperature increases by 15℃ to 90℃.
(30° C. lower than the motor temperature of 120° C.), which is not only an extremely low temperature compared to the temperature of the electric motor 5, but also a temperature gradient that is gentler than that of the motor. Therefore, the conventional overload protection device attached to the outer surface of the sealed container 1 operates with a delay in the rise in temperature of the electric motor, and there is a risk that the power will not be turned off when it should be turned off.

FIG. 6 shows another embodiment of the present invention, in which a heat-sensitive overload protection device is used and five glass-sealed terminals are installed in a thermosetting resin frame 10'. Pin insertion holes 12 are drilled at positions corresponding to the five pins of the glass-sealed terminal. A cavity 15' is provided in a part of the resin frame 10', and a pilot duty type thermal overload protection device 23 is housed and fixed therein.

That is, the fixed contact 17 is fixed to one end of the cavity 15', and the bimetallic fulcrum 18 is fixed to the other end. The bimetal fulcrum 18 has a movable contact 19
A bimetal 20' having at one end is fixed.

The fixed contact 17 and the movable contact 19 correspond to positions facing each other. The bimetal 20' operates by sensing only heat. 5 pin insertion holes 12
Two of the pin insertion holes 12 are pin insertion holes 12.
The pin contact piece 11 inserted into the inner wall of the connecting piece 2
It is electrically connected to the fixed contact 17 and the bimetal fulcrum 18 through 1a' and 21d. The remaining three pin insertion holes allow the pin contact piece 11 inserted into the inner wall of the pin insertion hole 12 to be connected to the connecting pieces 21b', 21c',
It is electrically connected to lead wire contact pieces 14' provided on the inner walls of the three lead wire insertion holes 13 through 21e. The symbols of these five pin contact pieces are
For convenience of the following explanation, thermal overload protection device 2
The two connected to the fixed contact 17 and the bimetal fulcrum 18 of No. 3 are designated as Y and Z, and the three connected to the lead wire 8 of the electric motor 5 are designated as U, V, and W. The electrical wiring diagram of the hermetic electric compressor constructed in this way is shown in the 7th page.
It becomes as shown in Fig. and Fig. 8. FIG. 7 shows the case of a three-phase induction motor, and FIG. 8 shows the case of a single-phase induction motor. In either case, it can be operated as an induction motor with a built-in pilot duty type overload protection device that detects only temperature to turn on and off an operating circuit (not shown).

According to each of the above embodiments, the overload protection device is located inside the sealed container 1 and is integrated into the clusters 9 and 9' that connect the glass sealed terminal of the sealed container and the lead wire 8 of the motor 5. Since the temperature of the electric motor 5 rises rapidly during overload operation of the compressor and the overload protection device should be immediately activated to turn off the power, the outer surface of the conventional sealed container 1 Compared to the case where the motor 5 is attached, it is not affected by the heat radiation from the closed container, and the heat generated by the motor 5 is directly propagated through the refrigerant gas, so that it can be operated in accordance with the rise in the temperature of the motor 5. . In addition, since the overload protection device is integrated into the clusters 9 and 9', there is no need to increase the installation space compared to conventional methods, and the end coil dimensions are smaller compared to the conventional structure in which the overload protection device is wrapped around the outer surface of the motor. Therefore, there is no need to increase the size of the hermetic electric compressor. Furthermore, since the overload protection device is integrated into the clusters 9, 9', it is possible to streamline the work of assembling the overload protection device to the hermetic electric compressor.

〔Effect of the invention〕

According to the present invention, the overload protection device is located inside the hermetic container and is integrated into the cluster, so that when the overload protection device is activated and the power should be cut off in the overload operating state of the compressor, , compared to conventional ones attached to the outside surface of a sealed container, it is not affected by heat radiation from the container.
The heat generated by the motor is directly propagated through the refrigerant gas, and the motor can be operated in accordance with the rise in temperature of the motor. Thereby, the overload protection device opens the electrical circuit to the motor when it should be switched off, so that the motor does not burn out.
In addition, since the overload protection device is integrated into the cluster, there is no need to increase the installation space compared to conventional methods, and the end coil dimensions are smaller compared to the conventional structure where the overload protection device is wrapped around the outer surface of the motor. There is no need to increase the size of the electric compressor. Furthermore, since the overload protection device is integrated into the cluster, it is possible to streamline the work of assembling the overload protection device to the hermetic electric compressor.

[Brief explanation of the drawing]

Figures 1 and 2 are longitudinal sectional views of a conventional hermetic electric compressor, Figure 3 is a longitudinal sectional view of a hermetic electric compressor showing an embodiment of the present invention, and Figure 4 is a longitudinal sectional view of a hermetic electric compressor used in the present invention. 5 is an electrical wiring diagram showing electrical connections using the cluster of FIG. 4; FIG. 6 is a sectional view of the cluster showing another embodiment of the present invention; FIG. 7 and FIG. 8 is an electrical wiring diagram when the cluster shown in FIG. 6 is used. 1...Airtight container, 4...Glass sealed terminal, 5...Electric motor, 8...Lead wire, 9,9'...Cluster, 12
...Pin insertion hole, 16...Overload protection device, 23...Heat-sensitive overload protection device.

Claims (1)

[Claims] 1. A sealed container, a rotary compression element located within the sealed container, an electric motor that drives the compression element, a glass-sealed terminal attached to the sealed container, and a lead wire between the glass-sealed terminal and the motor. The overload protection device is provided with a cluster that connects the glass-sealed terminal and the lead wire by being interposed between the clusters, and an overload protection device that opens and closes an electric circuit to the electric motor according to temperature changes inside the compressor. A hermetic electric compressor, characterized in that a load protection device is located within the hermetic container and integrated into the cluster.