JPH01198262A - Dc servomotor - Google Patents

Abstract

PURPOSE:To reduce operation faults of a brush and to prevent abnormal abrasion by dividing the power path to the brush into two parts, one through a brush spring and the other through a pigtail of the inside of a pigtail slot. CONSTITUTION:A motor is such that a magnet 1 is adhered to a housing 2, and a metal 3 is forcedly fitted to make a stator. A core 5 is forcedly fitted into a shaft 4, a commutator 6 is forcedly fitted and adhered, an armature coil 7 is wound on a slot of the core 5, an end of the coil is connected to a hook of the commutator 6, a plurality of oil flingers 8 are provided on the metal side of the commutator 6, and a tight-fit is made to make a rotor of the motor. A gap in the direction of thrust between the rotor and the stator is coordinated, a plurality of washers 9 are used for reducing friction torque, and an output shaft side is inserted into the stator as the side of the metal 3. According to the constitution, a brush coil is the first path of power to the brush as a good conductor, and a pigtail is taken out to make the second path of power to the brush.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a DC servo motor, and particularly to a DC servo motor with an improved rectification mechanism.

[Conventional technology] In a conventional DC servo motor, a rotor core and a commutator are fixed to a shaft inside a housing to which permanent magnets are bonded, windings are applied to the core, and the ends of the windings are connected to the commutator. Insert the rotor, insert the bearing from the inside, and attach the brush holder subassembly containing the pigtailed brush made of pure copper stranded wire pushed out by the spring to one of the two end brackets, and attach the placed on both sides,
After adjusting the positional relationship between the permanent magnet and the brush to a neutral point while observing the rectified waveform, the housing and two end brackets are fixed with screws to form the motor part.

Next, the rotating part of the rotation detector is fixed to the shaft by screwing, press-fitting, shrink-fitting, etc., and the sensor and waveform shaping circuit part are faced to the rotating part, and after temporarily fixing with screws, the gap is adjusted. After checking the amount detected by the sensor, fully tighten the screws. Thereafter, the rotation detection portion was covered with a cover to protect it from external forces, forming a rotation detector and configuring a servo motor.

In particular, regarding the rectifying mechanism section, the configuration of the brush section is disclosed in Japanese Utility Model Publication No. 62-13418 and Japanese Utility Model Application Publication No. 62-95.
No. 471, No. 62-95472, No. 62-84364
As described in the publication, it was designed to pass inside the brush coil screw.

[Problem to be solved by the invention]

In the above conventional technology, the smaller the motor, the smaller the brush, so the brush spring has to be made smaller.
The pigtail that passes inside the brush spring is deformed and gets caught on the inside of the brush spring when the brush spring expands and contracts, reducing or adding to the force of the brush spring, making it impossible to obtain appropriate brush pressure and causing abnormal brush wear. In some cases, the brush may not make contact to the specified amount.

In addition, when a pigtail is embedded in a small brush, the pressure direction during powder compaction is the longitudinal direction of the brush, and the laminated surface of carbon powder and metal powder is parallel to the commicita sliding surface, which causes brush wear. The problem was that it was fast.

As a solution to this problem, there is an example in which the pigtail is brought out from the side of the brush so that it does not pass through the brush spring, and the brush powder layering direction and the commi sliding surface are perpendicular to each other. The effect on pressure could not be completely eliminated.

The above-mentioned problem tends to become more pronounced especially when the motor current is to be increased, as the pigtail becomes thicker.

An object of the present invention is to provide an appropriate rectification mechanism for a small motor.

[Means to solve the problem]

The above purpose is to provide a brush slot and a pigtail slot in the rectifying mechanism, change the brush coil into a good electrical conductor, and use it as the first current path to the brush. Then, the diameter of the pigtail is reduced, and the pigtail is pulled out from the side of the brush to form a second current supply path to the brush. This makes it possible to secure the energizing current, reduce the resistance of the pigtail, and stabilize the contact pressure between the brush and commutator to a pressure that corresponds to brush wear. This improves abnormal brush wear and lack of contact caused by brush malfunction. achieved.

[Effect]

Applying current to the brush through the brush spring and pigtail allows the brush spring to be designed around spring characteristics, while the pigtail allows the cross-sectional area to be reduced by the amount of current flowing through the brush spring.

Also, it is possible to provide a pigtail slot and put the pigtail outside of the brush spring (coil spring).

Since the pigtail deforms when the brush spring is compressed and operates to prevent it from getting caught in the brush spring, it is possible to obtain a sliding surface pressure of the brush that corresponds approximately to the wear of the brush.

In addition, inserting the pigtail into the pigtail slot necessarily means pulling the pigtail out from the side of the brush, so that the direction in which the carbon powder and metal powder are laminated appears perpendicular to the sliding surface of the brush.

This allows the sliding surface pressure to be maintained at any part of the brush.

If the rectification conditions such as sliding speed and current are the same, the wear characteristics will be the same, so the brush life can be extended compared to a vertical push brush with a pigtail.

As described above, a rectifying mechanism with a long brush life can be formed even if the electromagnetic design is freely designed.

〔Example〕

Examples of the present invention will be described below.

FIG. 1 shows the structure of a motor, in which a magnet 1 is glued to a housing 2 made by drawing and molding a ferromagnetic material, and a metal 3 is press-fitted to form the stator of the motor.

Press-fit the iron core 5 into the shaft 4, press-fit and glue the Komichitaro, wind the armature coil 7 into the slot of the iron core 5, connect the coil end to the hook part of the Komichitaro, and attach multiple oil flingers 8 to the metal side of the Komichitaro. place,
In order to prevent the lubricating oil flowing out from the metal 12 from penetrating and passing through the space between the shaft 4 and the oil flinger 8 and reaching the surface of the Komichitaro, causing poor rectification and abnormal wear of the brush, the oil flinger 8 and the shaft are Make a tight fit between them and connect them to the rotor of the motor.

Then, in order to adjust the gap in the thrust direction between the rotor and stator, and to reduce metal wear and friction torque, a plurality of washers 9 are inserted, and the output shaft side is placed on the metal 3 side. Insert into stator.

On the Comichitaro side, a part of the brush holder of the plastic engineering plastic 10 is lengthened, and the metal 11 is lightly press-fitted or blind-fitted from the outside of the plastic engineering plastic 10 in order to stabilize the behavior of the brush during motor operation.

Next, a B engineering plastic holder 12 is attached to the B engineering plastic 10 and the housing 2 in order to prevent the metal 11 from falling off due to impact in the thrust direction, and to uniquely fix the B engineering plastic 1o to the housing 2. 12 is fitted into the groove, and when the B engineering plastic holder 12 is fixed to the housing 2, the position of the brush holder slot is set at the mechanical neutral point.

Then, a set of brush holders is inserted into the brush slot and pigtail slot of the B engineering plastic 10, and the B engineering plastic holder 12 is welded to the housing 2 to form a motor part.

Next, regarding the rotation detector installed in this motor,
An example of magnetic encoder implementation will be explained using FIG. 2.

A ferromagnetic detection gear 19 is fixed to the shaft 4 of the motor 18 at a position facing the magnetic sensor.

Then, on the slide 14 provided on the B engineering plastic 10,
Set the gap with the magnetic sensor part 15 to a specified value using a spacer, etc., confirm that the detection signal of the magnetic sensor is greater than the specified value, and then attach the B engineering plastic 10 and the magnetic sensor part 15 with instant adhesive 16. Fix between.

Next, the external circuit and connection connector 18 inserted into the radial groove 17 of the B engineering plastic 10 are soldered to the printed board 19, and the lead terminal 20 of a part of the magnetic sensor is soldered. and the connector 18, and cover with a protective cover 21 to form a magnetic encoder 22.

The configuration of the B engineering plastic 10 made of plastic molding will be described below with reference to FIGS. 3 to 6.

FIG. 3 is a cross-sectional view of the B engineering plastic 10, showing the brush slot 23. Pigtail slot 24° Metal receiving part 25 for housing metal 11. A detent 26 is provided to prevent plastic from expanding and metal from creeping at high temperatures. Then, the positioning protrusion 27 of the B engineering plastic holder 12 is placed on the top of the B engineering plastic 10. A fitting part 28 with the housing 2 is provided at the lower part, and the metal receiver is provided with a groove 2 in order to achieve accurate inner diameter accuracy of the part 25 and concentricity with the fitting part 28.
9 will be provided.

FIG. 4 shows a plan view of the B engineering plastic 10. B has a guide groove 30 for the engineering plastic holder 12, has a groove 31 for fixing the brush holder in the groove, and has a flat part 14 on the top surface.
This is a slide on which the magnetic sensor part 15 is placed.

FIG. 5 shows a side view of one side of the B engineering plastic 10. When the B engineering plastic holder 12 and the housing 2 are connected and fixed by welding, the recess 32 prevents welding slag from entering the motor.
This slag pocket was created to prevent deterioration of the coil insulation and prevent it from getting into gaps between the brush and metal, causing failures.

FIG. 6 shows a cross section in a direction perpendicular to the brush slot 23.

The pocket 33 is for inserting a connector 18 for connecting an external circuit soldered to the printed board 19 mounted in the groove 17. The recess 34 on the opposite side is a space for storing a filter for suppressing brush noise.

The groove 35 is formed between the magnetic sensor part 15 and the detection gear 13.
This structure allows a part of the magnetic sensor to slide stably when performing gap adjustment.

The claw 36 serves to prevent the one-touch encoder cover 21 from being removed.

Next, the B engineering plastic subassembly will be explained using FIGS. 7 and 8.

FIG. 7 is a plan view of the B engineering plastic section, and shows the printed board 19.
The external circuit connection connector 18 and the lead wire 37 are soldered to the groove 17, and fixed to the B engineering plastic 1o with an adhesive 38 to prevent removal.

As shown in the side view of FIG. 8, the brush holder 39 made of an elastic body is attached to the brush slot 23 of the B engineering plastic 1o.
Using this as a reference, one-touch setting is performed in the groove 31, and the lead wire 37 is connected to the tip 40 of the brush holder.

Next, using Figures 9 and 10, B engineering plastic holder 1
7 will be explained.

FIG. 9 is a plan view showing the hole 41, which is a relief hole in the small diameter portion of the metal 11, and is a blank hole to prevent the metal 11 from tilting during assembly.

The hole 42 is a fitting hole for positioning with the B engineering plastic 10, the screw hole 43 is for mounting a printed circuit board of a noise filter circuit, and the hole 44 is a fitting hole for positioning the noise filter circuit with the tip 40 of the brush holder 39 when mounting the noise filter. This is for connecting the filter's printed circuit board.

FIG. 10 is a side view, and the protrusion 45 is provided to ensure reliable contact connection with the encoder cover 21 for magnetic shielding and electrostatic shielding.

The points of the motor will be explained below with reference to FIGS. 11 to 16.

FIG. 11 is a plan view of the metal, and FIG. 12 is a cross-sectional view of the metal. When the motor reaches a high temperature, the oil impregnated in the metals 3 and 12 decreases in viscosity and expands, causing the plurality of grooves 46 on the outer periphery of the metal to flow out to the outside. Therefore, once the motor reaches an abnormally high temperature, the life of the metal may be significantly reduced.

To prevent this, it is made of stepped metal and has grooves 46 on the outer periphery.
This is so that the impregnating oil that comes out of the metal can easily adhere to it due to surface tension, and when the temperature of the metal drops, it will return to the inside of the metal.

Of the impregnated oil that has flowed out from the metal, the oil that has flowed along the shaft 4 will eventually get on top of the Komichitaro and enter between the segment pieces of the Komichitaro and the brush, causing the current distribution to become uneven and concentrate in one part. This causes abnormal electrical wear of the brushes.

To take this measure, an oil flinger as shown in FIG. 13 is provided. In the oil flinger 8, the impregnated oil that has flowed out from the metal 11 is blown away by the first oil flinger part 47, and the oil that has flown over is absorbed by the oil absorbing material 48, and the oil that exceeds the absorption limit of this oil absorbing material is The second oil finger part 49 scatters the metal-impregnated oil to prevent it from reaching the surface of the komichitaro, thereby extending the life of the brush.

On the other hand, the lifespan and noise of the brush are also affected by the processing of the komichitaro, the design of the winding, and the power supply voltage. As shown in FIG. 14, the outer shape of the commicitaro is processed using a rotary cutting machine, so that the edge shapes on the left and right sides of the segment 49 are generally different. For this reason, when the motor rotation direction is such that the brush hits the etched side with a small radius, the brush is momentarily repelled and sparks are generated, resulting in a short brush life and increased noise.

As a countermeasure for this, when machining the slits of the Comichitaro, we performed chamfering or R processing that exceeds the wear amount of the commutator during the ten-year life of the Comichitaro, and took care to reduce the resistance when the brush crosses the segment, thereby extending the life of the brush. The aim was to reduce noise and reduce noise.

Productivity will be explained using FIG. 15.

The parts of this motor are manufactured mainly by molding in order to improve productivity, and the use of screws is limited due to dimensions and materials, so assembly work is done by gluing and staking.

This mainly involves welding and press-fitting, so it is advisable to check in advance.

Therefore, before fixing the housing 2 and the B engineering plastic holder 12, which are the total assembly of the motor 18, by welding, the brushes, magnets, welding, etc. The parts were arranged in the same direction, the motor was set in the welding jig, magnetized, and the above-mentioned test was performed to make a comprehensive judgment of the quality of the parts.

Further, as shown in FIG. 16, the housing 2 is provided with a fitting part 51 for the B engineering plastic holder 12, the magnet 1 is adhered using this fitting part 51 as a reference, and the housing 2 and the B engineering plastic 10 are connected to the B engineering plastic holder 12. By fitting the stator to the brush, the relationship between the stator and the brush is determined, eliminating the need to adjust the neutral point while looking at the rectified waveform, which was previously done.

The configuration was designed to improve productivity.

Also, a magnetic sensor part 15 of the encoder and a detection gear 1
The gap adjustment between 3 is an adjustment in units of 10 μm,
When fixing is performed while applying mechanical force, subtle deformation of structural parts such as the end bracket of the motor 18 and the support base of the magnetic sensor part 15 results in the process of re-checking the gap and disassembling and re-fixing.

As a solution to this problem, as shown in Figure 17, after the gap adjustment is completed, without applying mechanical force to the structure, the motor 1
8 and a part of the magnetic sensor 15 are fixed with an instant adhesive 16.

A description related to the brush will be given using FIGS. 18 and 19.

As motors become smaller, brushes with pigtails
Since the pigtail 52 cannot be extended from the end surface direction of the brush 53 due to the molding process, it is common to extend it from the side surface of the brush 53 as shown in FIGS. 18(a) and 18(b). In this case, a method is used in which a part of the brush slot is cut and the pigtail 52 is connected to the source line.
As motors become smaller, they are less easy to assemble and are disadvantageous in terms of automatic assembly.

Furthermore, as shown in FIGS. 18(C) and (D), when the pigtail 52 is extended from the end surface of the brush 53, the pigtail 52 must be fixed to the brush 53 by a method called copper powder fixing, and the Workability is significantly lower than that of the above-mentioned braided pigtail brush.

In any of the pigtailed brushes shown in Fig. 18 (a) and (b) or (c) and (d), the sliding area of the brush becomes smaller as the motor becomes smaller, reducing the elastic force of the brush spring. I have to let it happen.

However, since the pigtail is embedded within the brush, it cannot be made smaller in proportion to the brush sliding area, and the drag of the pigtail cannot be ignored against the elastic force of the brush spring, which is fatal to the rectifying mechanism and shortens the life of the brush. give a great blow.

Therefore, according to Honjitsu, the brush shape is made into a pigtail structure as shown in FIGS. 18(e) and 18(f), and a protrusion for holding a brush spring is provided on the end face of the brush.

An enlarged view of the protrusion 61 of the 18th (e) brush is shown in FIG. 19. The protrusion 54 has a tapered tip with a protrusion to facilitate insertion of the brush spring, and a recess 55 is provided at the base of the protrusion 54 to improve stability after the brush spring is attached and to improve contact from the brush spring to the brush. do.

Considering that the brush spring is also an electric circuit, the brush spring is made of an alloy or plated wire of a good electrical conductor such as copper or silver, and is configured to suppress the heat generation itself of the spring.

Then, the number of strands of the pigtail is reduced by the amount of electricity applied to the brush spring, and the configuration is made to soften the pigtail.

Figure 20 is a diagram showing the parts of the brush, and Figure 18 (E).
A conductive spring 56 is set on the brush shown in and (f), and the end opposite to the brush 53 is fixed to the brush holder 39 by soldering or the like. The pigtail 52 has a habo spring 56
It is connected to the brush holder 39 with its free length.

21st. FIG. 22 is a diagram showing a set of brush holders set in B engineering plastic, FIG. 21 is a cross-sectional view in the direction perpendicular to the slot, and FIG. 22 is a cross-sectional view in the axial direction of the slot.

The brush spring shares the motor current, and the pigtail, which has a smaller wire diameter, is housed in the pigtail slot, which is wider than the inner diameter of the brush spring, as shown in the diagram above, which reduces the degree of entanglement with the brush spring and reduces the amount of entanglement of the brush. The contact surface pressure is highly dependent on the cross-sectional area of the brush and the strength of the brush spring.

As mentioned above, conductive structures that reduce the insulation distance from the wiring and the outer frame are eliminated inside the B engineering plastic, and the creepage distance and clearance distance from the brush to the non-live metal body are reduced to the conventional product. By increasing the length, we were able to improve the insulation deterioration caused by brush dust.

Further, by integrally molding the brush holder slot portion with B engineering plastic, accuracy can be improved.

As a result, the behavior of the brush is stabilized, and there is an effect of improving rectification waveform defects and abnormal wear of the brush.

〔Effect of the invention〕

As described above, according to the present invention, by dividing the current supply to the brush into the path passing through the brush spring and the path passing through the pigtail in the pigtail slot, even if the brush current is determined based on the electromagnetic design, the brush spring design can be adjusted. There is no current restriction caused by this problem or brush malfunction due to pigtail snagging, and the sliding surface pressure of the brush can be maintained at an appropriate level, which prevents abnormal brush wear and provides a long-life DC servo motor. be.

[Brief explanation of the drawing]

Figure 1 shows the structure of the motor, Figure 2 shows the structure of the magnetic encoder, Figure 3 shows the cross section of B engineering plastic, Figure 4 shows the plane of B engineering plastic, and Figure 5. Figure 6 is a cross-sectional view of B engineering plastic (direction perpendicular to the brush slot), Figure 7 is a partial assembly diagram (plan view) of B engineering plastic, and Figure 8 is a diagram of B engineering plastic. Department diagram (
(Side view), Figure 9 is a plan view of the B engineering plastic holder, Figure 10 is a side view of the B engineering plastic holder, and Figure 1 is a side view of the B engineering plastic holder.
Figure 1 is a plan view of the metal, Figure 12 is a cross-sectional view of the metal, Figure 13 is a diagram showing the structure of the oil flinger, Figure 14 is a diagram showing the slit part of the commutator, and Figure 15 is an external view of the motor. Figure 16 is a diagram showing the housing assembly;
Fig. 17 is a diagram showing the plane of the encoder, Fig. 18 is a diagram showing the configuration of the brush, Fig. 19 is an enlarged view of the brush, and Fig. 20 is a diagram showing the configuration of the brush.
21 is a cross-sectional view of the brush mounting (perpendicular to the slot), and FIG. 22 is a cross-sectional view of the brush mounting (in the slot direction). 1... Magnet, 2... Housing, 3... Metal, 4... Shaft, 5... Iron core, 6... Commitator, 7... Armature coil, 8... Oil filter Ringer, 9... Washer, 10 ・Plastic engineering plastic (B engineering plastic), 11... Metal, 12...
・B engineering plastic holder, 13...detection gear, 14...
・Slide, 15... Part of magnetic sensor, 16... Adhesive, 17... Groove, 18... Connector, 19...
・Printed board, 20... Lead terminal, 21... Protective cover (encoder cover), 22... Magnetic encoder, 23... Brush slot, 24... Pigtail slot, 25... Metal receiver , 26... Detent, 27... Positioning protrusion, 28... Fitting portion, 29...
...Groove, 30...Guide groove, 31...Groove, 32...
・Indentation (pocket), 33...pocket, 34...
Hollow, 35...Groove, 36...Claw, 37...Lead wire, 38...Adhesive, 39...Brush holder, 4
0... Tip, 41... Hole, 42... Hole, 43...
...Screw hole, 44...hole, 45...protrusion, 46...
・Groove, 47... Part of the first oil flinger, 48...
・Oil absorbing material, 49... Part of second oil flinger, 50
... Segment, 51... Fitting portion, 52... Pigtail, 53... Brush, 54... Protrusion, 55...
- Hollow, 56...Brush spring. 10th 20th 3121) 61+Ki/6th raguchime] ■ @8 no ql skewer (0 kuchi b th (30 wrath 15 (¥) Satoru 1q no taku 1'l [D 8zO's

Claims (1)

[Claims] 1. In a DC servo motor configured such that a motor is formed on one side of the molded insulating material and a rotation detector is formed on the other side, a brush slot is integrated into the intermediate molded insulating material. A pigtail slot is provided parallel to this slot, and a coil spring is inserted between the brush and the brush holder.
A DC servo motor characterized by electrical connection with pigtails. 2. In item 1, D characterized in that a good electrical conductor is formed on the surface of the coil spring or beryllium copper is used.
C servo motor. 3. The DC servo motor according to item 1, characterized in that a partition plate is provided in a part of the brush slot and the pigtail slot.