JP2023147406A - Vacuum discharge testing method - Google Patents

Abstract

An object of the present invention is to provide a vacuum discharge testing method that can efficiently and accurately test the insulation properties of a coil.
A vacuum discharge testing method according to the present disclosure is based on the current flowing when a voltage is applied between a coil 14 and an electrode 13 located near the coil 14 in a vacuum state. A vacuum discharge testing method for testing, in which, in a non-vacuum state, if the current flowing when a voltage is applied between the coil 14 and the electrode 13 is equal to or higher than a predetermined value, depressurization is started to create a vacuum state. do.
[Selection diagram] Figure 1

Description

The present disclosure relates to a vacuum discharge testing method.

Patent Document 1 discloses a vacuum discharge testing method for testing the insulation of a coil by applying a voltage between a coil and an electrode in a vacuum state and checking for the presence or absence of corona discharge.

Japanese Patent Application Publication No. 2002-148300

The surface of the enameled wire (copper wire) constituting the coil is coated with a coating such as lamination to ensure insulation so that short circuits between the enameled wires do not occur between the layers of the coil. Examples of a method for determining whether or not a defect such as a pinhole has occurred in the coating include a vacuum discharge inspection method disclosed in Patent Document 1.

If a voltage is applied between the coil and the electrode in a state where the coating has defects such as pinholes, that is, the insulation of the coil is not ensured, there will be a gap between the defective part of the coil and the surface of the electrode. Vacuum discharge occurs and a large current of 100 mA or more flows. On the other hand, when the insulation of the coil is ensured, no vacuum discharge occurs between the coil and the electrode, and the current flowing remains at about several mA. This determines whether the coil is good or defective.

However, this testing method does not allow large currents to flow between the coil and the electrodes even when the coil is not properly set in the testing device or when an abnormality occurs in the power supply or pressure reducing device. , there is a risk that the coil will be erroneously determined to be good. In addition, if it is confirmed that the coil is not properly set in the inspection equipment after depressurizing, the vacuum state is released once, the coil is reset in the inspection equipment, and then the vacuum state is restored again. This creates unnecessary effort and time.

The present disclosure has been made to solve such problems, and an object of the present disclosure is to provide a vacuum discharge testing method that can efficiently and accurately test the insulation properties of a coil.

A vacuum discharge inspection method according to the present disclosure includes a vacuum discharge inspection in which the insulation of the coil is inspected based on the current that flows when a voltage is applied between the coil and an electrode located near the coil in a vacuum state. A vacuum discharge testing method in which, in a non-vacuum state, if a current flowing when a voltage is applied between the coil and the electrode is equal to or higher than a predetermined value, pressure reduction is started to create a vacuum state. be. Thereby, it is possible to provide a vacuum discharge testing method that can efficiently and accurately test the insulation of a coil.

The electrode may include a holding mechanism for the coil, and may be arranged so as to partially contact the inside of the coil. With such a configuration, it becomes easy to set the coil in the inspection device.

When the outer length of the coil is A, the width of the electrode is L, the wire width of the coil is W, and the inspection length of the electrode is φd, A≦L+W+φd may be satisfied. With such a configuration, the entire circumference of the coil can be inspected while increasing the degree of freedom in setting the coil within the inspection device.

Further, the vacuum discharge testing method according to the present disclosure performs a preliminary test based on a current that flows when a voltage is applied between a coil and an electrode located near the coil in a non-vacuum state, and A vacuum discharge inspection method in which, if the inspection is passed, the main inspection is performed based on the current that flows when a voltage is applied between the coil and the electrode in the vacuum state after transitioning from a non-vacuum state to a vacuum state. It is. Thereby, it is possible to provide a vacuum discharge testing method that can efficiently and accurately test the insulation of a coil.

According to the present disclosure, it is possible to provide a vacuum discharge testing method that can efficiently and accurately test the insulation properties of a coil.

1 is a configuration diagram of an inspection apparatus that executes a vacuum discharge inspection method according to Embodiment 1. FIG. 1 is a flowchart showing a vacuum discharge testing method according to Embodiment 1. FIG. FIG. 3 is a diagram illustrating criteria for preliminary inspection according to the first embodiment. FIG. 3 is a diagram illustrating the configuration of an electrode according to Embodiment 1.

<Embodiment 1>
Embodiments of the present disclosure will be described below with reference to the drawings. FIG. 1 shows the configuration of an inspection apparatus that executes a vacuum discharge inspection method according to this embodiment. FIG. 2 is a flowchart of the vacuum discharge testing method according to this embodiment. FIG. 3 shows the criteria for preliminary inspection according to this embodiment. FIG. 4 shows the structure of the electrode according to this embodiment.

The inspection device 10 shown in FIG. 1 includes an AC power source 11, a container 12, an electrode 13 connected to the AC power source 11, and a pressure reducing device (not shown) that reduces the pressure inside the container 12.

The coil 14 is set in the container 12 so as to be placed near the electrode 13. Further, one end of the enameled wire constituting the coil 14 has the surface coating removed, and the removed portion is connected to the AC power source 11.

The coil 14 according to this embodiment is, for example, a coil for a motor. Although the coil 14 shown in FIG. 1 has a winding shape, it is not limited to this, and may have a different shape such as a disk shape.

The electrode 13 according to this embodiment is arranged inside a coil 14 having a winding shape. Further, the electrode 13 has a rectangular shape, and the outer surface of the electrode 13 is parallel or substantially parallel to the inner surface of the coil 14 having a wound shape.

Note that the electrode 13 shown in FIG. 1 may be removable, or may be placed near the coil 14 and then set in the container 12 together with the coil 14. This makes it easy to set the coil in the inspection device.

Before reducing the pressure in the container 12, a voltage is applied between the coil 14 and the electrode 13 from the AC power supply 11, for example in an atmospheric pressure state. Since the coil 14 and the electrode 13 are not in contact with each other, theoretically no current flows between them. However, since the coil 14 and the electrode 13 have a small amount of capacitance, it is assumed that a capacitor C is provided between the coil 14 and the electrode 13 (the dotted ellipse in FIG. 1). ), a weak current actually flows.

The present inventors applied a voltage of several hundred V or more between the coil 14 and the electrode 13 with a part of the electrode 13 in contact with the coating on the surface of the coil 14 or in a state close enough to contact it. They discovered that a current on the order of microamperes flows.

In the present disclosure, "nearby" indicating the positional relationship between the coil 14 and the electrode 13 refers to a state in which the coil 14 and the electrode 13 are in contact with the coating on the surface of the coil 14 or in a state close enough to contact.

Here, we will explain the preliminary inspection to determine whether the coil is properly set in the inspection device and the main inspection to determine whether the insulation properties of the coil are ensured using the flowchart in FIG. 2. .

The preliminary inspection is an inspection performed before the pressure is reduced, and is represented by steps (S101, S102, S103) surrounded by dotted lines in FIG. Note that this preliminary inspection is typically performed at atmospheric pressure, but may also be performed at higher pressure than atmospheric pressure or at a lower pressure that does not reach vacuum. That is, the preliminary inspection is performed in a non-vacuum condition.

First, the coil 14 is set near the electrode 13 in the inspection device 10 (S101). As mentioned above, since the electrode 13 may be removable, it may be placed in the vicinity of the coil 14 and then set in the container 12 together with the coil 14.

Next, a voltage is applied between the coil 14 and the electrode 13 from the AC power supply 11 (S102), and the amount of current flowing between the coil 14 and the electrode 13 is measured (S103).

Here, the criteria for the preliminary inspection will be explained using FIG. 3. In the graph of FIG. 3, the horizontal axis indicates the amount of current flowing between the coil 14 and the electrode 13, and the vertical axis indicates the number of coil samples.

When the coil 14 is properly set in the inspection device 10, a weak current on the order of microamperes is detected between the coil 14 and the electrode 13 ("normal" in FIG. 3). Therefore, it is determined that the coil 14 is properly set in the inspection device 10.

On the other hand, if the coil 14 is not properly set in the inspection device 10, no current will flow even if a voltage is applied between the coil 14 and the electrode 13 (below the lower limit of detection), or even if current flows It is on the order of microamperes or less ("abnormal" in FIG. 3). Therefore, it is determined that the coil 14 is not properly set in the inspection device 10.

In order to perform such a preliminary inspection, in S103, the inspection device 10 compares the amount of current flowing between the coil 14 and the electrode 13 with a predetermined reference value, and determines that the amount of current is equal to or greater than the reference value. If it is, it is determined to be "normal", and if it is less than the reference value, it is determined to be "abnormal". In this embodiment, the reference value is about 10 μA.

If it is determined that the coil 14 is not properly set in the inspection device 10, the coil 14 is reset in the inspection device 10 and the preliminary inspection is performed again.

When it is determined that the coil 14 is properly set in the inspection device 10, that is, when the preliminary inspection is passed, the main inspection is performed in a vacuum state. First, a pressure reduction is started to bring the inside of the container 12 into a vacuum state using a pressure reduction device (S104). Thereafter, a vacuum discharge test is performed by applying a voltage between the coil 14 and the electrode 13 from the AC power supply 11 (S105), and the amount of current flowing between the coil 14 and the electrode 13 is measured (S106).

When a vacuum discharge occurs between the coil 14 and the electrode 13 and a current of more than a predetermined value (approximately 100 mA) flows, there is a defect in the coating of the coil 14, so the coil 14 is determined to be a defective product. . On the other hand, when no vacuum discharge occurs between the coil 14 and the electrode 13 and the amount of current flowing is less than or equal to a predetermined value, the coil 14 is determined to be a good product.

In this way, by performing a preliminary inspection to determine whether the coil is properly set in the inspection device before depressurizing, it is possible to quickly proceed to the main inspection. Furthermore, it is possible to prevent erroneous determinations that occur when the coil is not properly set in the inspection device or when an abnormality occurs in the power supply, pressure reducing device, or the like.

Next, the structure of the electrode according to this embodiment will be explained using FIGS. 4(a) and 4(b). Although FIGS. 4A and 4B describe the long axis direction of the electrode, that is, the horizontal direction, the short axis direction, that is, the vertical direction may be read in the same way.

The electrode 13 shown in FIG. 4(a) also serves as a holding mechanism for the coil 14 having a wound shape, and is configured to partially contact the inside of the coil 14. Further, the electrode 13 has an inspection length φd, and when the electrode width is L, it has an inspection possible range of L+2d (see the broken line in FIG. 4(a)). Note that the inspection length φd is a numerical value determined experimentally.

Here, the outer length of the coil 14 is A, and the wire width is W, and the inspection length φd is set so as to satisfy A≦L+W+φd. As a result, as shown in FIG. 4(b), even if the coil 14 moves due to vibration or the like after it is set in the inspection device 10, the entire circumference of the coil 14 can be kept within the inspection range of the electrode 13. can. Therefore, the entire circumference of the coil 14 can be inspected while increasing the degree of freedom in setting the coil 14 within the inspection device 10.

Further, since the electrode 13 is configured to partially contact the inside of the coil 14, the capacitance between the coil 14 and the electrode 13 increases. This increases the current that flows when a voltage is applied between the coil 14 and the electrode 13, making it easier to make a determination in the preliminary test.

Note that the present disclosure is not limited to the above embodiments, and can be modified as appropriate without departing from the spirit.

10 Inspection device 11 AC power supply 12 Container 13 Electrode 14 Coil

Claims (4)

A vacuum discharge testing method for testing the insulation of the coil based on a current flowing when a voltage is applied between the coil and an electrode located near the coil in a vacuum state, the method comprising:
In a non-vacuum state, if a current flowing when a voltage is applied between the coil and the electrode is equal to or higher than a predetermined value, pressure reduction is started to create a vacuum state. The vacuum discharge testing method according to claim 1, wherein the electrode includes a holding mechanism for the coil and is arranged so as to partially contact the inside of the coil. The vacuum discharge test according to claim 2, wherein A≦L+W+φd is satisfied, where A is the outer length of the coil, L is the width of the electrode, W is the wire width of the coil, and φd is the inspection length of the electrode. Method. Performing a preliminary test based on the current flowing when a voltage is applied between the coil and an electrode located near the coil in a non-vacuum state,
If the preliminary inspection is passed, the main inspection is performed based on the current that flows when a voltage is applied between the coil and the electrode in the vacuum state after transitioning from a non-vacuum state to a vacuum state. Vacuum discharge Inspection method.

Images