JPH09133198A - Motor with reduction gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor with a compact, lightweight reduction gear at low cost. SOLUTION: A high frequency power supply 31L on the low frequency side is put in action, and a gear P is induction-heated by a low frequency side heating coil 30L to heat the root part surface of a tooth to high temperature as shown by the void in a right upper figure (1). A high frequency power supply 31H on the high frequency side is actuated, and the gear P is induction-heated by a high frequency side heating coil 30H. As shown by the void in a figure (2), only the surface is heated to high temperature on the whole from the root part to the tip excluding the center part of the tooth, and then water is jetted to the surface of the gear P in a red heat state by a water jetting device 36 for rapid cooling. The surface is thereby quenched so as to obtain quenching along tooth form down to the root as shown by the void in the figure (2). The gear thus reinforced is used to constitute reduction mechanism. Since the gear strong in both flexure and wear can be obtained by two frequency quenching, miniaturization and weight reduction can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor provided with a multi-stage speed reducer using spur gears, and more particularly to a reduction gear used as a gear on the first stage input side of the speed reducer by forming a gear at the end of the rotary shaft of the induction motor. The electric motor with a machine.

[0002]

2. Description of the Related Art A general-purpose induction motor is usually made to have a two-pole structure or a four-pole structure for downsizing, and therefore, its rated rotation speed is 1000 revolutions / minute (rpm) or more. It is common to have On the other hand, as a load rotationally driven by this electric motor, there is a load having a relatively low rotational speed such as a hoisting machine, and in this case, therefore, it is necessary to drive it via a reduction mechanism. Therefore, in order to apply to such an application, an electric motor with a reducer, which has been conventionally called a geared motor or the like, is provided on the market, and an example thereof is shown in FIG.

In the motor with reduction gear shown in FIG. 5, a reduction gear mechanism having a reduction ratio of, for example, 25: 1 is provided integrally with a four-pole induction motor by using spur gears in two stages. Thus, an electric motor having a rotation speed of about 60 revolutions per minute is obtained. In the figure, M is an induction motor and R is a reduction gear.

The induction motor M includes a housing 1 and end brackets 2, 3, a stator 4, a stator core 5, a stator coil 6, a rotor 7, a rotor core 8, a rotor coil 9, a rotary shaft 10 and a bearing. It is composed of 11, 12 and the like. The housing 1 is made of, for example, cast iron or aluminum so that the inner shape is a substantially cylindrical shape, and a stator 2 including a stator core 3 and a stator coil 4 is attached to the inside thereof.

End brackets 2 and 3 are respectively positioned at both ends of the housing 1 by a spigot fitting or the like, and then fixed by through bolts or the like as shown in the drawing. And these end brackets 2, 3
Are bearings 1 and 1 made of ball bearings, respectively.
2 is attached, whereby the rotary shaft 10 is rotatably held.

A rotor 7 is located inside the stator 2, and the rotor 7 has a cage shape made up of a rotor core 8 and a molded aluminum product formed on the rotor core 8. The rotor coil 9 and the rotor coil 9 are attached to the rotary shaft 10 and are rotatably held.

Further, the rotary shaft 10 is constructed so as to project into the speed reducer R from a bearing 12 provided on the end bracket 3 on the speed reducer R side. A pinion 13, which serves as a small gear on the first stage input side of the reduction mechanism, is formed.

The speed reducer R comprises a casing 14 which is adapted to be mounted on the opposite side of the end bracket 3 of the induction motor M, in which the first stage reduction shaft 15 is installed.
And the second stage output shaft 16, bearings 17 to 20, first spur gear 2
The first and second spur gears 22 and the pinion 2 which is directly formed on the first stage reduction shaft 14 and serves as a small gear on the second stage input side.
3 and 3 are built in.

The first stage reduction shaft 15 has an end bracket 3
Is rotatably held by a bearing 17 mounted on the casing 14 and a bearing 18 mounted on the casing 14, and the second stage output shaft 16 is a bearing 19 also mounted on the end bracket 3 and a bearing mounted on the casing 14. It is rotatably held by 20.

The pinion 19 formed on the rotary shaft 10 of the electric motor meshes with the spur gear 21 attached to the first stage reduction shaft 15, and the pinion 23 formed on the first reduction shaft 15 is , Meshes with the spur gear 22 attached to the second stage output shaft 16.

Therefore, when the induction motor M rotates, the pinion 13 of the rotary shaft 10 thereof drives the gear 21 to rotate and receives the first stage deceleration. Next, the gear 22 is rotationally driven by the pinion 23 formed on the first reduction shaft 15, and the second stage deceleration is given here. Therefore, the reduced rotation is obtained on the output shaft 16. become.

By the way, in order to obtain a large reduction ratio and to reduce the size of such a motor with a reduction gear, it is necessary to configure the gear with a diameter as small as possible. As a result, each gear is required to have high strength. . In particular, the pinion 13, 23
Requires high strength. Therefore, a method of strengthening gears by heat treatment has been conventionally used.

This gear strengthening method involves quenching and tempering using steel as the material of the gear. At this time, specifically, induction hardening and carburizing quenching are used. is there. Therefore, first, the induction hardening will be described. In this hardening method, an eddy current is generated in the material by electromagnetic induction to heat the material. As shown in FIG. 2, a heating coil 30 is used and this is used. The high frequency power source 31 is fitted to the gear P such as a pinion to be quenched.
Therefore, the gear P is heated by applying a high-frequency current having a frequency of about several KHz, and heat treatment such as quenching is performed, which is relatively low in cost.

In FIG. 2, reference numerals 32 and 33 are pivot shafts for supporting, which hold the gear P rotatably, and move the coil 30 while rotating the gear P, so that the entire surface of the teeth of the gear P is rotated. To be heated.

Next, carburizing and quenching is a method in which a gear is placed in a carburizing furnace, heated to raise the temperature, impregnated with carbon on the surface, and then quenched and tempered. It is characterized by being easily cured.

[0016]

Among the above-mentioned prior arts, in induction hardening, unless the entire gear is heated and hardened, the root of the tooth is not hardened. As a result, in FIG. As shown, since the inside of the tooth is hardened, the tooth part becomes too hard as a whole, and the gear becomes brittle, on the other hand. Since the work is put into the machine, there is a problem that the work takes time and the cost becomes high.

The present invention has been made in view of the above prior art, and requires a short processing time for strengthening the gears.
It is an object of the present invention to provide a motor with a reducer, which has a sufficient strength at a low cost and which is small and lightweight.

[0018]

The above object is to provide an electric motor having at least two stages of spur gear reduction mechanisms, wherein at least one of the plurality of gears constituting the reduction mechanism is of high or low type. This is achieved by constructing a gear that has been strengthened by induction hardening at the frequency of.

Since the gear is generally made of steel or alloy steel, it can be hardened by heat treatment such as quenching to improve its strength. Then, in induction hardening, a high-frequency current is passed through the coil to inductively heat the gear. At this time, if the frequency of the high-frequency current passed through the coil is low, heat is generated from all the teeth of the gear,
As the frequency increases, there is a characteristic that the heat generating portion is limited to the surface.

Therefore, if two types of frequencies, high and low, are used together with induction heating by these, it is possible to heat only the surface along the tooth surface to the root without heating the inside of the tooth so much. It is possible to increase the strength by hardening the entire surface by quenching while leaving the inside of the.

Quenching using these two high and low frequencies is called dual-frequency quenching. With this quenching, only the portion from the surface to a predetermined depth is hardened along the tooth profile of the gear. As a result, the tooth surface is hard and wear-resistant, and the tooth becomes strong against bending and impact load with stickiness remaining inside the tooth. A gear that is resistant to abrasion can be formed. Therefore, by using this dual-frequency-quenched gear, it is possible to provide a small-sized and lightweight electric motor with a reducer at low cost.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a motor with a speed reducer according to the present invention will be described in detail with reference to the illustrated embodiments.

The overall structure of the electric motor with reduction gear according to one embodiment of the present invention is apparently the same as the induction motor with reduction gear explained in FIG. 5, except that it is used in the reduction gear mechanism R. Since only the strengthening process applied to the gears such as the pinion and the spur gear that are present is different, only the strengthening process of the gears according to the present invention will be described below.

FIG. 1 shows an example of an apparatus used for dual-frequency hardening of gears according to an embodiment of the present invention.
30L is a low frequency side heating coil, 30H is a high frequency side heating coil, 31L is a low frequency side high frequency power source, 31H is a high frequency side high frequency power source, 34 is a rotating mechanism, 35 is a support base, 36 is water injection It is a device, and these are adapted to perform a dual-frequency quenching process on the gear P.

Here, the pivot shafts 32 and 33 hold the gear P as in the device of FIG. 2, but in the device of FIG. 1, the lower pivot shaft 32 is rotated by the rotating mechanism 34. And the upper pivot shaft 33
Is fixed to the support base 35 by a support structure (not shown).

The high frequency power source 31L on the low frequency side generates a high frequency voltage of, for example, 3 KHz, whereby 3 KH.
It functions to supply the high frequency current of z to the heating coil 30L on the low frequency side. High frequency power source 31H
Generates a high frequency voltage of, for example, 150 KHz, and thereby supplies a high frequency current of 150 KHz to the heating coil 30H on the high frequency side.

The rotating mechanism 34 includes a lower pivot shaft 32.
To rotate in the direction of the arrow a shown in the figure at a predetermined slow rotation speed.
5 functions to move the rotating mechanism 34 and the upper pivot shaft 33 up and down in the direction of the arrow b or the arrow c shown.

As shown in the drawing, the water injection device 36 is made in the shape of a hollow ring, and is provided with a number of nozzles inside, and by supplying water from a pump (not shown), The nozzle serves to inject water toward the center of the ring.

Next, the dual frequency quenching process by the apparatus of FIG. 1 will be described. First, as shown in the drawing, the gear P to be hardened is moved to the upper and lower pivot shafts 32, 33.
To be held. Then, with the gear P held,
As shown by the arrow b, the support base 35 is moved upward so that the lower end of the gear P comes to the position of the heating coil 30L on the low frequency side.

Next, the low frequency side high frequency power source 31L and the high frequency side high frequency power source 31H are operated, the induction heating operation of the gear P by the low frequency side heating coil 30L and the gear by the high frequency side heating coil 30H. The induction heating operation of P is started, and at the same time, the pivot shaft 32
Is slowly rotated in the direction of arrow a by the rotating mechanism 34, and this time, the support base 35 is slowly lowered in the direction of arrow c.

As a result, the gear P is first heated by the heating coil 30L on the low frequency side, and as a result, the surface of the root portion of the tooth is heated to a high temperature as shown by the white outline on the right side of the drawing. Then, by heating by the heating coil 30H on the high frequency side, the surfaces other than the root part of the tooth are heated to a high temperature this time, which is also shown in outline in the figure. As described above, except for the central portion of the tooth, only the surface is heated to a high temperature from the root portion to the tip, and the surface comes out from the heating coil 30H on the high frequency side to the lower side.

Here, if the water jetting device 36 jets water to the surface of the gear P in a red heat state and quenches it, the surface is hardened, and as a result, as shown in white in the figure, Quenching along the tooth profile up to the root can be obtained.

Therefore, if a predetermined treatment such as a tempering treatment is performed thereafter, the tooth surface will be hard and the inside will be soft and tenacious, so that a gear P that is strong against abrasion and bending can be obtained. By configuring the reduction mechanism R shown in FIG. 5 using the pinion or spur gear that has been subjected to the dual-frequency hardening treatment, it is possible to easily obtain a small-sized and low-cost electric motor with a reduction gear.

Further, according to this embodiment, since the tempering process can be performed in the same process, the tact time becomes faster, and the process can be performed in a shorter time as compared with the case of the carburizing and quenching process, and the cost is sufficiently low. Becomes possible.

Next, another embodiment of the present invention will be described. The entire structure of the electric motor with reduction gear according to this embodiment is the same as that of the induction motor with reduction gear described in FIG.
It is apparently the same, and the only difference is that the strengthening process performed on the gears such as the pinion and spur gear used in the reduction mechanism R is different.

First, in this embodiment, as the pinion 13, not only the above-mentioned two-frequency quenching process but also a shot peening process and a polishing process are used. Here, first, this shot peening process will be described with reference to FIG. First, in FIG. 4, 36 is a shot grain accelerating device, 37 is a rotary table, 38 is a driving device, 39 is a pivot shaft, and the accelerating device 36 is made of a fine steel ball with a diameter of 1 mm or less, for example. Shot particles S of, for example, 50 m /
It works by accelerating to a high speed of sec and radiating.

Therefore, the gear P is placed on the rotary table 37 which is rotated in the direction of the arrow by the drive mechanism 38, and it is held by the pivot shaft 39, so that the gear P being rotated is rotated. The shot particles S injected from the accelerator 36 are made to collide with the surface to finish the surface, which is the shot peening process in this embodiment.

Accordingly, after gear cutting is performed on the end of the rotary shaft 10, the two-frequency-quenched pinion 13 is mounted on the rotary table 37 and held by the pivot shaft 39, and the rotary table 37 is rotated to accelerate the accelerator. The production process of the pinion 13 is completed by injecting the shot particles S from 36, hitting the surface of the pinion 13 for shot peening, and then further polishing to finish the surface.

Next, after the gear cutting process, the first spur gear 21 is
Hardened by the induction hardening apparatus shown in FIG. 2, and then shot peened and polished. Here, the first stage pinion 13 and the spur gear 21 rotate at a relatively high speed. Therefore, in order to reduce noise, the polishing process is performed as described above,
This makes it possible to sufficiently suppress the generation of noise.

Next, the pinion 2 serving as the second stage pinion.
For No. 3, after the gear cutting, two-frequency quenching treatment and shot peening treatment are used. Then, the second spur gear 22
After the gear cutting step, as with the first spur gear 21, the one subjected to the quenching treatment by the induction hardening device shown in FIG. 2 and then the shot peening treatment is used.

Here, the spur gear has a larger number of teeth than the pinion, and therefore, the number of times the teeth are meshed is small, so there is a margin in terms of strength. Therefore, in this embodiment, the spur gear is not subjected to dual-frequency quenching but is subjected to normal induction-quenching, whereby a sufficient balance of strength between the gears is maintained, and It is possible to eliminate useless manufacturing steps and sufficiently reduce the cost.

Therefore, according to this embodiment, since the residual compressive stress remains on the treated tooth surface by the shot peening treatment, a gear having teeth with higher strength can be obtained, and the reduction mechanism R is further improved. The size and weight can be reduced, and the flaws and burrs on the tooth surface are leveled and smoothed by the shot peening treatment, so that the noise can be sufficiently suppressed in combination with the polishing treatment.

Here, in recent years, the electric motor with reduction gear is often used in a multi-story parking lot for residential use, and therefore, quietness is an essential requirement. According to this embodiment, , It can fully meet this demand.

[0044]

According to the present invention, since dual frequency quenching is used to strengthen the gear, the tooth surface is hard and the inside has a soft and tenacious structure, so that a gear that is resistant to wear and bending can be formed. A small and lightweight electric motor with a reducer can be easily provided at low cost.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an example of a dual frequency quenching apparatus used in an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of a normal induction hardening apparatus.

FIG. 3 is an explanatory view showing a quenching state by a normal induction hardening apparatus.

FIG. 4 is an explanatory diagram of a shot peening device.

FIG. 5 is a cross-sectional view showing an example of an electric motor with a reducer.

[Explanation of symbols]

M Induction motor R Reduction mechanism 1 Housing 2, 3 End bracket 4 Stator 5 Stator iron core 6 Stator coil 7 Rotor 8 Rotor iron core 9 Rotor coil 10 Rotation shaft 11, 12, 17, 18, 20 Bearing (ball Bearing) 13 1st stage pinion (small gear) 14 Casing 15 1st stage reduction shaft 16 2nd stage output shaft 19 Bearing (plain bearing) 21 1st spur gear 21 22 2nd spur gear 22 23 2nd stage pinion 30L Low-frequency side heating coil 30H High-frequency side heating coil 31L Low-frequency side high-frequency power source 31H High-frequency side high-frequency power source 34 Rotating mechanism 35 Support stand 36 Water injection device

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yasunori Miyanaga 7-1, 1-1 Higashi Narashino, Narashino City, Chiba Prefecture Industrial Equipment Division, Hitachi, Ltd. (72) Masayoshi Inoue 7-1, Higashi Narashino, Narashino City, Chiba Prefecture Hitachi Industrial Co., Ltd. Industrial Equipment Division (72) Inventor Mikihiko Dairiki 7-1-1 Higashi Narashino, Narashino City, Chiba Prefecture Industrial Equipment Division Hitachi, Ltd. (72) Hiroaki Ando 7-chome Higashi Narashino, Narashino City, Chiba Prefecture 1-1 Hitachi Industrial Co., Ltd. Industrial Equipment Division (72) Inventor Eiichiro Sugawa 7-11 Higashi Narashino, Narashino City, Chiba Prefecture Hitachi Industrial Equipment Division (72) Inventor Yukio Chihara Higashi Narashino, Narashino City, Chiba Prefecture 7-1-1 No. 1 Industrial Equipment Business, Hitachi, Ltd. (72) Inventor Kenji Mizutani 7-1, 1-1 Higashi Narashino, Narashino City, Chiba Prefecture Hitachi Industrial Co., Ltd. Industrial Equipment Division (72) Ikuo Mori 7-1, 1-1 Higashi Narashino, Narashino City, Chiba Hitachi, Ltd. Equipment Division (72) Inventor Noriaki Chino 7-1-1 Higashi Narashino, Narashino City, Chiba Prefecture Hitachi Industrial Products Division (72) Inventor Shuji Hirota 7-1-1 Higashi Narashino, Narashino City, Chiba Hitachi, Ltd. Factory Industrial Equipment Division

Claims (3)

[Claims] 1. A motor having a spur gear reduction mechanism of at least two stages, wherein at least one gear among a plurality of gears constituting the reduction mechanism is subjected to induction hardening treatment at two high and low frequencies. An electric motor with a speed reducer, which is composed of reinforced gears. 2. The invention according to claim 1, wherein among the gears other than the gear that has been subjected to the quenching treatment,
An electric motor with a speed reducer, characterized in that at least one gear is composed of gears reinforced by an induction hardening treatment with a single frequency. 3. The electric motor with a speed reducer according to claim 1, wherein the at least one gear is polished after shot peening.