JPS6341428B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a motor device for a compressor, in particular to a hermetically sealed or semi-sealed motor, and more particularly to troubleshooting a power supply circuit for this motor.
Regarding how to.

The use of electric motor compression devices housed within a hermetic or semi-hermetic shell has recently become increasingly popular, particularly in refrigeration applications where motor compression devices are used to compress refrigerant vapor. In many of these motor compression systems, the power supply circuit for the motor includes a switch that is responsive to motor conditions such as temperature or current. This switch, commonly referred to as an internal cut-off switch, is located within a sealed shell and is usually fixed directly to the motor. An internal disconnect switch is electrically located between the motor and the power supply, and the switch is normally closed to conduct current from the power supply to the motor. However, if the switch senses the occurrence of an undesirable condition, such as excessive motor temperature, the switch opens and disconnects the motor from the power source, thereby terminating motor operation. When the undesired condition is alleviated, the internal shutoff switch closes again allowing the motor to start again.

Because internal shutoff switches are located within a sealed or semi-closed shell, it can be difficult to determine whether the switch is open or closed. This makes it difficult under certain circumstances for a technician or repair person to determine why the motor is not working. For example, if an external factor seems to be telling the motor to run, but the motor is not running, the internal shutoff switch is closed and the motor may be defective and not running. . Alternatively, the motor may simply not run because the internal shutoff switch is open. In the vast majority of cases, most repair personnel and technicians can quickly and accurately determine why the motor is not working. However, sometimes mistakes are made; for example, a technician may determine that the motor is defective when the fact is that the motor is not defective and is simply not operating because the internal cut-off switch has properly temporarily terminated its operation. You may conclude that it is not working because of the Based on this erroneous conclusion, the technician may return the motor to the manufacturer for repair or replacement, creating unnecessary hassle for all involved and wasting time, money, and other materials.

According to the present invention, the above-mentioned other difficulties of the prior art can be overcome by a compressor motor device comprising an electric motor, a shell housing the motor, and a power supply circuit. The power supply circuit includes conductive conduit means for connecting the motor to a current source, a switch positioned within the shell and electrically located in the conduit means, and a bypass circuit for conducting current through the motor around the switch. The switch changes from a closed, conductive state to an open, non-conductive state to selectively terminate motor operation.

Next, embodiments of the present invention will be described with reference to the accompanying drawings.

In the drawings, it is a schematic diagram of a power supply circuit 10.
A circuit 10 connects an electric compressor motor 12 to a power source represented in the drawing by lines L1 and L2.
As will be apparent to those skilled in the art, the present invention can be used with many types of electric motors.
In the preferred embodiment shown in the drawings, however,
Motor 12 is a single-phase induction motor with a main or running winding 14 and an auxiliary or starting winding 16, with windings 14 and 16 located electrically in parallel to each other. Also, as will be apparent to those skilled in the art, circuit 10 and motor 12 can be used with many types of power sources. For example, one suitable type generates approximately 230 volts alternating current at a frequency of approximately 60 hertz.

Circuit 10 includes lines L3, L4, L5 and L6, with a start switch 18 located on line L3, a capacitor 20 on line L4, a resistor 22 on line L5, and a normally closed internal disconnect switch 24 on line L6. . Preferably, the power supply circuit 10 comprises a plurality of additional devices not shown in the drawings.

For example, the circuit 10 includes a constant temperature switch, an indicator lamp,
It is also equipped with safety switches such as a low oil pressure cut-out switch. Such devices are well known in the art and have been omitted from the drawings for clarity.

Returning to the explanation of the drawing, the operation 14 is connected to lines L3 and L.
6 to the power supplies L1, L2, and the starting winding 16 is connected to the power supply via lines L3, L4 and L6. According to this arrangement, closing the start switch 18 connects the motor 12, specifically its windings 14 and 16, via lines L1 and L2, thereby starting the motor. As is well known in the art, capacitor 20 creates a phase difference between the currents through run and start windings 14 and 16, thereby increasing the torque produced. Motor 12 is housed within shell 26, and preferably the motor is hermetically or semi-enclosed within the shell. Also located within the shell 26 is an internal shutoff switch 24, which is preferably physically secured directly to the motor 12 and senses one or more motor parameters such as current or temperature. As mentioned above, the internal shutoff switch 24 is normally closed, but will open if the switch senses the occurrence of an unsatisfactory condition, such as excessive motor temperature.

As previously mentioned, in prior art compressor motor devices of the general type described above, when the internal shutoff switch is opened, the compressor motor is disconnected from the power supply and motor operation is temporarily terminated. . Also, as mentioned above, with this common prior art device, it may be difficult for a repair person or technician to determine why the motor is not running. In particular, it is difficult to determine whether the cutoff switch is open or not.
In view of this, circuit 10 of the present invention includes a bypass circuit that conducts current through motor 12 around switch 24, specifically through line L5 and resistor 22.
It is equipped with More specifically, resistor 22 is connected to line 1
The resistance of the resistor 22 is preferably large enough, e.g. 10,000 or 15,000 ohms, to ensure that the motor 12
be smaller than necessary to operate the device. With this arrangement, when only switch 24 is open, motor 12 is temporarily inoperable, but circuit 10 is still intact and energized.

This fact can be advantageously used by repair personnel and technicians to facilitate troubleshooting of circuit 10. More specifically, if a cause in circuit 10 prevents operation of motor 12, a technician can perform a test to determine whether this cause is due to internal disconnect switch 24 being open. This fault-finding test is performed by connecting the circuit 10 to a power supply, which may for example use power supplies L1, L2 or a much lower voltage test power supply. The technician then measures the magnitude of the current flowing through resistor 22. If this magnitude is greater than zero, circuit 10 is complete and the only possible cause of inoperative motor 12 is that switch 24 is open. However, if the magnitude of the measured current is zero, then the circuit 10 is interrupted and a cause other than the switch 24 being open, such as a defective motor 12 or an interruption in line L6, prevents the motor from operating. There is a high possibility that

Note that electrical wires (not shown) can extend from each end of the resistor 22 to the exterior of the shell 26 to facilitate direct measurement of the current through the resistor. However, preferably this current is measured indirectly by simply measuring the current through lines L3 and L6.

As will be appreciated by those skilled in the art, when an interrupted or open switch 24 in circuit 10 prevents motor 12 from operating, the magnitude of the current through wires L3 and L6 will be equal to the magnitude of the current through resistor 22. equal. Furthermore, in practice the circuit 10 or the resistor 22
It may be easier to measure the resistance of the circuit 10 instead of the current flowing through it. As will be apparent to those skilled in the art, when the only reason motor 12 does not operate is because disconnect switch 24 is open, circuit 1
A resistance of 0 is substantially equal to the resistance of resistor 22.
In contrast, in most other cases where causes in circuit 10 prevent operation of motor 12, the resistance of the circuit is essentially infinite.

The current and resistance tests described above are quick, reliable, and easy to understand and apply. In many situations, this test reduces the amount of time it takes for a technician to determine why the motor is not working. This in turn reduces the cost of troubleshooting inactive motors and increases technician productivity. Additionally, the present invention increases the accuracy of the fault search process. In particular, the present invention allows the technician to reliably identify when the motor is not operating solely because the shutoff switch is open. Thus, the likelihood that a technician will mistakenly assume that a defect in the power supply circuit or motor is preventing its operation is greatly reduced when, in fact, the internal disconnect switch is simply open. Accordingly, the present invention can be effectively used to reduce the number of motors that are incorrectly returned to the manufacturer for repair or replacement. This can, for example, save much of the time, money, and efforts of manufacturers previously spent testing properly functioning equipment that is falsely identified as defective. .

Although it is clear that the invention disclosed herein is well calculated to satisfy the above objectives,
Numerous modifications may be devised by those skilled in the art, and it is intended that the appended claims cover all such modifications as fall within the true spirit and scope of the invention. I want to be understood.

[Brief explanation of the drawing]

The drawing is a schematic diagram of a compressor motor arrangement using the present invention. In the figure, 10...power supply circuit, 12...motor, 14...
Working winding, 16... Starting winding, 18... Starting switch, 20... Capacitor, 22... Resistor, 24... Internal cutoff switch, 26... Outer shell.

Claims (1)

[Scope of Claims] 1. A compressor motor and a power supply circuit for the motor, wherein the power supply circuit is located in series between a current source and the compressor motor, and has an internal line break that selectively conducts current between the two. switch, and a high impedance bypass circuit that conducts around and through the extension cut-off switch when the extension cut-off switch is open. connecting a power supply circuit to a current source, further measuring the magnitude of the current flowing through the high impedance bypass circuit L5, and operating the compressor motor 12 and the power supply circuit 10 if the current is small; 1. A fault searching method comprising the steps of maintaining the motor 12 and the power supply circuit 10 inoperative in the case of zero current. 2. A fault search method according to claim 1, wherein the measuring step further includes a step of measuring the resistance of the power supply circuit 10.