JP7074901B2 - How to use a railroad vehicle - Google Patents

Description

The present invention relates to a method of using an electric vehicle or a method of using a railroad vehicle.

An inverter is a device or a part of a device that converts DC power into an AC voltage is called an inverter. Battery-powered AC converters, DC electric railway inverters, etc. On the other hand, in Japan, in order to obtain alternating current with different numbers of phases, voltage, and frequency, a rectifier (converter) for converting single-phase alternating current and three alternating current of a commercial power supply to direct current with a rectifier and then converting it to alternating current again. ) And an inverter are combined, and the entire power conversion device housed in the same package is often called an inverter. Elevators, pumps, fans, railroad vehicles, electric vehicles, air conditioners, equipment used in refrigerators and factories, backup power supplies such as servers and personal computers, in-vehicle inverters that use 100V household equipment with 12V power supply for automobiles, the sun It is possible to control the output of various electric appliances such as power conditioners in optical power generation from home appliances to large equipment.
Conventionally, a metal of bearing steel (SUJ2 or the like) has been used for a bearing member close to an inverter, particularly for a bearing ball.

On the other hand, since the inverter controls the inverter control circuit using a high-frequency current, an EDM current (current that destroys the metal surface due to a discharge phenomenon) and a high-frequency circulating current are likely to occur. In particular, in metals such as bearing steel, a phenomenon called electrolytic corrosion occurs and the bearing life is shortened, making it impossible to provide a reliable rotary drive.
In recent years, in order to solve such a problem, attempts have been made to ground the shaft of the motor or to attach a metal that shields electromagnetic noise to the outer circumference of the motor. For example, in Japanese Patent Application Laid-Open No. 2006-328273 (Patent Document 1), the bearing is filled with conductive grease to obtain a grounding effect. However, the conductive grease has problems such as aging and liquid leakage.

Japanese Unexamined Patent Publication No. 2006-328273

However, both required some accessories to be attached to the bearings or motors. Since the installation of accessories increases the work process, the manufacturing process is complicated.
The present invention has been made to solve the above-mentioned problems, and is used in the vicinity of an inverter driven at 50 Hz or higher, in which the occurrence of electrolytic corrosion phenomenon is suppressed by the generation of EMD current and high-frequency circulating current. It provides a bearing. Further, since the occurrence of the electrolytic corrosion phenomenon is suppressed, the reliability of the inverter and the electric equipment using the inverter can be improved.

One aspect of the present invention is a method of using a railroad vehicle provided with an inverter motor, wherein the railroad vehicle has an inverter control circuit for driving a pulse width modulation, and the drive frequency of the inverter motor is 50 Hz or more and 2000 Hz or less. The rolling bearing includes an inner ring made of SUJ2 material, an outer ring made of SUJ2 material, and an electric resistance value of 10 ¹⁰ Ω. A plurality of bearing balls , including an insulating bearing ball of cm or more, are provided, and the insulating bearing ball has a metal member and a spray film provided on the surface of the metal member, and is insulated. When the number of bearing balls is P (pieces), the maximum rotation speed of the rolling bearing in the usage environment is M (rpm), and the drive frequency of the inverter motor is F (Hz), P × M ≧ 60F is satisfied. Moreover, since P is an integer of 6 or more, the occurrence of electrolytic corrosion is suppressed. The electrical equipment provided with the rolling bearings is preferably any one of equipment used in factories, servers, personal computers, elevators, pumps, fans, home appliances, electric vehicles, and railroad vehicles.

According to the present invention, in the bearing used in the vicinity of the inverter, since the bearing having an electric resistance value of ¹⁰⁷ Ω · cm or more is used among a plurality of rolling elements, it is possible to suppress the generation of EMD current and high frequency circulating current. .. Therefore, even if the inverter control circuit is driven by a current having a drive frequency of 50 Hz or higher, it is not necessary to attach a member for obtaining the grounding effect. As a result, the assembly process of the bearing and the motor can be simplified, and the reliability of the motor can be improved.

The figure which shows an example of the bearing of this invention.

The rolling bearing used in the vicinity of the inverter of the present invention is an inverter operating at a frequency of 50 Hz or higher. The rolling bearing has a plurality of rolling elements, and at least one rolling element has electrical resistance due to insulating ceramics or an insulating coating. It is characterized in that the value is ¹⁰⁷ Ω · cm or more.
The inverter has an inverter control circuit that converts direct current into alternating current. In alternating current, plus and minus change periodically, and this periodic change becomes the frequency. The inverter is a method of controlling the rotation speed according to the change of frequency. Compared to the method of controlling the number of revolutions by combining multiple gears, the weight can be reduced because complicated components such as gear changes are not required.

The higher the frequency of the inverter, the faster the speed of change of plus and minus. At the time of this plus or minus change, electromagnetic induction occurs around the inverter control circuit. This electromagnetic induction is transmitted to the inside of the bearing through a conductor such as a metal part. The transmitted electromagnetic induction becomes an EMD current and / and a high frequency circulating current. When an EMD current and / or a high-frequency circulating current is generated, it is also transmitted to the rotating shaft and rolling element (bearing ball) used in the bearing. At this time, if the rotating shaft and the rolling element are conductive members such as bearing steel (SUJ2), an electrolytic corrosion phenomenon occurs due to the EMD current and / or the high frequency circulating current. Due to the electrolytic corrosion phenomenon, the rotating shaft or rolling element is corroded, and it becomes impossible to maintain a uniform rotational motion. In particular, bearings used in the vicinity of an inverter with an operating frequency of 50 Hz or higher are prone to electrolytic corrosion.
On the other hand, in the present invention, among a plurality of rolling elements used for bearings used in the vicinity of the inverter, at least one rolling element has an electric resistance value of ¹⁰⁷ Ω · cm or more by insulating ceramics or an insulating coating. I am using something.
Further, the larger the number of rolling elements having an electric resistance value of ¹⁰⁷ Ω · cm or more, the better, and it is preferable that all rolling elements have an electric resistance value of ¹⁰⁷ Ω · cm or more. Further, the electric resistance value is preferably 10 ¹⁰ Ω · cm or more. Further, the electric resistance value shall be measured by an electric resistance measuring instrument by the two-terminal method.

By using an insulating rolling element having an electric resistance value of ¹⁰⁷ Ω · cm or more, it is possible to prevent the EMD current and / or the high-frequency circulating current from being transmitted to the rotating shaft and the rolling element.
Examples of the rolling elements having such insulating properties include those containing at least one selected from aluminum oxide, zirconium oxide, silicon nitride, silicon oxide, fluororesin, and engineering resin as a main component.
Examples of the ceramics containing at least one of aluminum oxide, zirconium oxide, silicon nitride, and silicon oxide as a main component include ceramics sintered bodies obtained by adding a sintering aid and sintering them, if necessary. The ceramic sintered bodies of aluminum oxide, zirconium oxide, silicon nitride, and silicon oxide are all insulators (insulating ceramic sintered bodies) having an electric resistance value of ¹⁰⁷ Ω · cm or more. The sintering aid shall be selected so as not to reduce this insulating property. Among the ceramic sintered bodies, a silicon nitride sintered body using yttrium oxide as a sintering aid is preferable because it has excellent sliding characteristics.

Further, as a rolling element having an electric resistance value of ¹⁰⁷ Ω · cm or more, at least one type of thermal spray film selected from zirconium oxide, silicon nitride, silicon oxide, chromium oxide, fluororesin, and engineering resin is applied to the surface of the metal member. There is also one that has been given.
As described above, the electrolytic corrosion phenomenon occurs in the metal member, but by providing the insulating sprayed film, it is possible to maintain the same insulating property as the insulating ceramic sintered body. The film thickness of the sprayed film is preferably in the range of 2 to 300 μm. If the film thickness of the sprayed film is less than 2 μm, film peeling may occur, and if it exceeds 300 μm, no further effect can be obtained. Further, since these sprayed films have a good affinity with the bearing steel (SUJ2), excellent bonding strength can be obtained.

Comparing the insulating ceramic sintered body and the insulating sprayed film, the sprayed film requires a film forming process, so that the manufacturing process is complicated. In addition, uniform control of the film thickness is required. Therefore, a rolling element made of an insulating ceramic sintered body is preferable.
FIG. 1 shows an example of a bearing. In the figure, 1 is a bearing, 2 is a rolling element (bearing ball), 3 is an inner ring, and 4 is an outer ring. The inner ring is fixed to the rotating shaft and functions as a bearing. The outer ring, inner ring, and rotating shaft are made of bearing steel (SUJ2).
Normally, 8 to 20 rolling elements are used for bearings. If at least one rolling element having the above-mentioned insulating property is used, electrolytic corrosion can be suppressed in the bearing used in the vicinity of the inverter operating at 50 Hz or higher.
Regarding how many rolling elements should be insulated, the number of rolling elements with an electrical resistance value of ¹⁰⁷ Ω · cm or more is P (pieces), and the rotation speed of the bearing is M (rpm). ), When the drive frequency of the inverter is F (Hz), it is preferable to satisfy P × M ≧ 60F. The rotation speed M (rpm) of the bearing is the maximum rotation speed in the usage environment.

In the present invention, it is preferable to use all rolling elements having an insulating property having an electric resistance value of ¹⁰⁷ Ω · cm or more. However, the insulating rolling elements are more expensive than those made of bearing steel (SUJ2). Therefore, it is effective to reduce the cost by replacing a part of the plurality of rolling elements with a rolling element made of bearing steel. At this time, if the relationship satisfies P × M ≧ 60F, electrolytic corrosion can be effectively suppressed.
For example, when the rotation speed M of the bearing is 5000 rpm and the drive frequency F of the inverter is 200 Hz, P × 5000 ≧ 60 × 200, P ≧ 2.4, so that three or more bearings have an electrical resistance value of ¹⁰⁷ Ω · cm or more. If it is set to, the electrolytic corrosion can be effectively prevented.

The number of rolling elements (bearing balls) mounted on the bearing is arbitrary, but is usually in the range of 8 to 20. For example, when the drive frequency is 3000 Hz and the rotation speed is 5000 rpm, P × M ≧ 60F → P × 5000 ≧ 60 × 3000 → P ≧ 36, and when the P value is equal to or more than the number of rolling elements, all the rolling elements are electric. An insulating rolling element with a resistance value of ¹⁰⁷ Ω · cm or more shall be used.

In addition, when electrolytic corrosion occurs, the part in contact with the rolling element such as the inner ring or the rotating shaft, or the rolling element itself is scraped. As a result, stable rotational motion cannot be provided. In addition, a method of measuring the sound during rotation is effective for determining whether or not the motion is stable. For example, when the sliding sound at a constant rotation speed is electrolytically eroded, the sliding sound becomes louder.
Further, it is preferable that the drive frequency of the inverter is 4000 Hz or less. It is possible to effectively prevent electrolytic corrosion by using a rolling element with insulating properties, but if the frequency becomes too high, the electrolytic corrosion suppressing effect may be insufficient with the insulating properties of the rolling elements alone. .. Therefore, when an insulating rolling element is used, it is suitable for a bearing used in the vicinity of an inverter having a drive frequency of 50 to 4000 Hz. More preferably, it is 50 to 1000 Hz.

The inverter is configured by combining such a bearing and a control circuit. Examples of the control circuit include an AC / DC converter, an inverter control circuit, a thyristor as a switching element, an IGBT element, and the like. PWM (Pulse Width Modulation) drive is generally used for the inverter control circuit. Since the inverter bearing of the present invention suppresses the generation of electrolytic corrosion, even if the inverter control circuit and the bearing are installed in the vicinity of, for example, within 1 m, they are not easily affected by electrolytic corrosion. Therefore, it is not restricted by the arrangement of the control circuit and the bearing. Therefore, it can be applied from home appliances such as air conditioners and washing machines to the vicinity of inverters of various electric appliances such as electric vehicles and railway vehicles. In other words, it is possible to provide highly reliable electrical equipment that is not affected by electrolytic corrosion. In addition, the neighborhood within 1 m includes both the bearing of the inverter motor and the bearing arranged near the inverter motor.

Hereinafter, embodiments of the present invention will be described with reference to examples.
(Examples 1 to 4, Comparative Example 1)
A bearing for an inverter was manufactured by incorporating eight rolling elements (bearing balls) having a diameter of 1 cm into an inner ring (inner diameter 5 cm) and an outer ring (outer diameter 8 cm). The inner ring and outer ring were made of bearing steel (SUJ2).
As rolling elements, SUJ2 spheres (electrical resistance value 10 ⁴ Ω · cm) and silicon nitride sintered spheres (electrical resistance value 10 ¹² Ω · cm or more) were prepared and used at the ratios shown in Table 1. ..
Inverter motors for electric appliances were manufactured by incorporating such bearings for inverters into inverter motors. An electrolytic corrosion test of each inverter motor was performed. The bearing was installed in the inverter motor (inverter and bearing are arranged within 1m).
The electrolytic corrosion of the inverter motor is measured by measuring the sound intensity with a microphone (pickup sensor) when the inverter motor is operated continuously for 400 hours at a frequency of 100 Hz and a rotation speed of 7000 rpm on the outer ring side, and the sensor output exceeds 30 dB. The case was defined as "presence", the vibration exceeding 25 dB and 30 dB or less was "slightly present", and the vibration less than 25 dB was "absent". The sliding noise after 1 hour of motor operation was less than 25 dB. The measurement results are shown in Table 1.

As can be seen from Table 1, when the rolling bearing of this embodiment was used, it was confirmed that the vibration was suppressed to a low level and no electrolytic corrosion occurred in any case. This is because the bearing according to the embodiment has P × M ≧ 60F, and P × 7000 ≧ 60 × 100 to P ≧ 0.9. Therefore, electrolytic corrosion was prevented in all of those using one or more insulating rolling elements.

(Examples 5 to 8, Comparative Example 2)
A bearing for an inverter motor was manufactured by incorporating 12 rolling elements (bearing balls) having a diameter of 1 cm into an inner ring (inner diameter 8 cm) and an outer ring (outer diameter 10 cm). The inner ring and outer ring were made of bearing steel (SUJ2).
As rolling elements, SUJ2 spheres (electrical resistance value 10 ⁴ Ω · cm) and silicon nitride sintered spheres (electrical resistance value 10 ¹² Ω · cm or more) were prepared and used at the ratios shown in Table 2. ..
Next, the same inverter motor as in Example 1 was manufactured except that the drive frequency of the inverter motor was changed to 800 Hz and the rotation speed was changed to 8000 rpm. Similarly, the presence or absence of electrolytic corrosion was confirmed by the presence or absence of increased vibration. The bearing was installed in the inverter motor (inverter and bearing are arranged within 1m). The results are shown in Table 2.

As can be seen from the table, P × M ≧ 60F, P × 8000 ≧ 60 × 800, and P ≧ 6. No electrolytic corrosion was confirmed in Examples 6 to 8 satisfying this condition, but it was slightly present in Example 5 which did not satisfy this condition.

(Examples 9 to 12)
In Example 1, as the insulating rolling element, a SUJ2 provided with an aluminum oxide sprayed film (thickness 3 μm) having an electric resistance value of 10 ¹⁰ Ω · cm or more was used, and the same measurement was performed. The inverter motor and bearings were arranged within 1 m. The results are shown in Table 3.

Even if the insulating rolling element had an electrical resistance of 10 ¹⁰ Ω · cm, it could be effectively used.

(Examples 13 to 15)
Example 13 was a silicon nitride sintered body (electrical resistance value 10 ¹² Ω · cm or more), Example 14 was an engineering resin (electrical resistance value 10 ¹³ Ω · cm), and a chromium oxide spray film (thickness 100 μm) was applied. A SUJ2 ball (electrical resistance value of ¹⁰⁸ Ω · cm or more) was used as Example 15 to configure an inverter bearing under the conditions shown in Table 4, and the presence or absence of electrolytic corrosion was measured by the same method as in Example 1. The diameter of the rolling elements was unified to 1 cm, and the bearings used had a total number of rolling elements of 16. The inverter motor and bearings were arranged within 1 m. The results are shown in Table 4.

From P × M ≧ 60F, P ≧ 36 in Example 13, P ≧ 20 in Example 14, and P ≧ 40 in Example 15. In each case, the P value was larger than the total number of rolling elements, so all of them had to be insulating rolling elements.

1 ... Bearing 2 ... Rolling element (bearing ball)
3 ... Inner ring 4 ... Outer ring

Claims (5)

How to use a railroad vehicle equipped with an inverter motor
The railroad vehicle
A control circuit that has an inverter control circuit for pulse width modulation drive and controls the drive frequency of the inverter motor to 50 Hz or more and 2000 Hz or less.
It is equipped with a rolling bearing installed at a position within 1 m from the control circuit.
The rolling bearing is
Inner ring made of SUJ2 material and
An outer ring made of SUJ2 material and
A plurality of bearing balls, including an insulating bearing ball having an electrical resistance value of 10 ¹⁰ Ω · cm or more, are provided.
The insulating bearing ball is
With metal parts
It has a thermal spraying film provided on the surface of the metal member, and has.
When the number of insulating bearing balls is P (pieces), the maximum rotation speed of the rolling bearing in the usage environment is M (rpm), and the drive frequency of the inverter motor is F (Hz), P × M ≧ A method of using a railroad vehicle that suppresses the generation of electrolytic corrosion by satisfying 60F and having P be an integer of 6 or more. The method of use according to claim 1, wherein the electrolytic corrosion is corrosion of at least one member selected from the group consisting of the inner ring, the outer ring, the bearing ball, and the rotating shaft to which the inner ring is fixed. The method of use according to claim 1 or 2, wherein the control circuit controls the drive frequency of the inverter motor to 50 Hz or more and 1000 Hz or less. The method of use according to any one of claims 1 to 3, wherein the thermal spray film has a thickness of 2 μm or more and 300 μm or less. The electric resistance value of the insulating bearing ball is 10 ¹² Ω · cm or more, and the electric resistance value is 10 12 Ω · cm or more.
The method of use according to any one of claims 1 to 4, wherein the metal member is made of SUJ2 material .

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