US3863336A

US3863336A - Method of manufacturing flat-type rotors

Info

Publication number: US3863336A
Application number: US342412A
Authority: US
Inventors: Kunihiro Noto; Hiroaki Mizoguchi
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 1972-03-22
Filing date: 1973-03-19
Publication date: 1975-02-04
Anticipated expiration: 1992-02-04
Also published as: JPS4895506A

Abstract

An armature coil is wound in place by use of a jig having pins fixed on a flat plate, a shaft is disposed at the center of the coil, the coil with the shaft is put in a mold using the jig, and resinous material is injected into the mold to make an integrated rotor.

Description

Unlted States Patent 1 [111 3,863,336

Noto et al. Feb. 4, 1975 [54] METHOD OF MANUFACTURING [56] References Cited FLAT-TYPE ROTORS UNITED STATES PATENTS [75] Inventors: Kunihiro Noto, Katsuta; Hiroaki 2,759,116 8/1956 Glass 310/266 X Mizoguchi, Hitachi, both of Japan 3,077,658 2/1963 Wharton 29/625 M h m1 Assignee= Hitachi, Tokyo, Japan 3123323 5/1333 Bui'ffl 53/235 22 Filed: Man 19 1973 3,599,325 8/1971 Burr et al 29/597 [2]] Appl' 3424412 Primary Examiner-Carl E. Hall Attorney, Agent, or FirmCraig & Antonelli [30] Foreign Application Priority Data Mar. 22, 1972 7 Japan 47-28147 [57] ABSTRACT An armature coil is wound in place by use of a jig hav- [52] U.S. Cl 29/597, 29/598, 29/605, i pins fixed on a fl plate, a Shaft is disposed at the [51] Int Cl 3l0lgg g lgg center of the coil, the coil with the shaft is put in a l' 1 -y d t.l...td 58 Field of Search 29/597, 598-, 605; 310/43, mo 6 ml resmus ma em e into the mold to make an integrated rotor.

10 Claims, 15 Drawing Figures Pmmmrm 4191? saw 1 OF 4 F'IG.3

PATENTEDFEB 41% 3,863,336

SHEEI 2 0F 4 PIC-7.6

PATENIED 41% 3; 863.336

SHEET 3 [IF 4 PATENTEDFEB' 4191s 3,863,336

SHEET u 0F 4 I FIG. I30

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a rotor of a flat-type motor and the method of making the same, and more particularly to aflat-type electric motor wherein a coil is wound in a flat space to form an armature coil.

2. Description of the Prior Art A print motor has been known as one of flat-type motors having a short length in the axial direction. In the actually used print motors, there are more motors in which the armature circuit is formed by arranging conductive pieces and insulating materials alternately and connecting by welding the ends of the conductive pieces than motors in which the armature circuit is formed by print wiring. In such a print motor, the conductive pieces are not accumulated on'an insulating plate but arrangedlaterally at equal intervals. Therefore, the length in the axial direction of the rotor is equal to the sum of the thickness of the insulating plate and the thickness twice as large as the thickness of the conductive pieces. Thus, the construction of the rotor is made extremely thin. The print motor of this type has a good response because the moment of intertial is small, and accordingly is commonly used as a servomotor.

On the other-hand, the feature of flat-type motors having a flat appearance characterizes the use of the flat-type motors in comparison with general cup-like magnet motor. In practice, there are many cases wherein the flat type motors are preferred from the viewpoint of design and saving of space, for example in case of motors for blowers employed in air conditioners or cooling and heating apparatus for automobiles. For instance, in case of blowers for car heaters or car air conditioners generally comprising a sirocco fan and a cup-shaped motor, it becomes difficult to mount the blower to the engine room if the axial length of the blower becomes too long. In general, therefore, it has been common to form a recessed boss on the fan on the opposite. side to-the motor thereof and make a part of the motor mated with the recessed portion of the inside of the fan to save the space occupied by the blower.

ments is too many. Further, although the commutator surface can be easily made parallel to the shaft in a print motor by forming an armature coil and a commutator portion separately and connecting the both electrically, it is impractical and cannot be put into practical use due to its low work efficiency. The second reason is that the print motor cannot be easily manufactured satisfying various motor dimensions. This is because the armature circuit portion is processed by punching and the like and accordingly a large number of motors of the same dimension can be advantageously manufactured, but it is impractical to manufacture certain amount of motors of various dimensions since a great cost and long time is necessary to prepare the different molds. For example, in case of motors to be used for cooling and heating apparatus for automobiles, various dimensions are required to comply with various types of car models and various requirements of customers and the number of the respective dimensions is not always properly large.

In addition to the above described flat-type motors, it has been known in the art to directly wind a coil on a disc and mold it with a resin into an integrated unit, or to wind a coil on a pin fixed to a resinous disc and heat and press it to bury the coil into the disc to form a rotor. There has been no method of making flat-type rotors which is practical in efficiency of production, performance, and manufacturing cost.

SUMMARY OF THE INVENTION The primary object of the present invention is to provide a rotor of a flat-type motor having short axial length, small size, small weight and low price, and a method of manufacturing the same.

Another object of the present invention is to provide a rotor of a flat-type motor having high performance and being able to be manufactured with any dimensions required, and a method of making the same.

The features of the present invention lies in manufacturing a rotor by winding in place an armature coil by This construction, however, hinders smoothair flow within the fan and decreases the effective cross section of the fan and lowers the fan efficiency. If the motor is made flat in shape, the axial length thereof is markedly short and the outer diameter of the motor may be smaller than the outer diameter of the fan, and accordingly, the blower can be made compact as a whole and there is no need to decrease the effective cross section of the fan.

However, print motors have not been put into practical use in the above mentioned filed for the following reason. The first reason is that the print motor is disadvantageous from the viewpoint of noise, vibration, life and so forth. This is because a part of the armature coil serves as a commutator and is subject to brush pressure in the axial direction, and accordingly, the armature is comparatively weak in comparison with the'general cup-shaped magnet motor and high accuracy in processing the commutator cannot be expected, and the commutator portion is deformed during revolution due to the brush pressure, the brush touch to the coil is affected by thrust, and the number of commutator seguseof a disc-like jig having pins fixed thereto, arranging a shaft at the center of the coil, placing the coil with the shaft in a mold employing said jig, and injecting a resin into the mold to integrally mold the coil and the shaft to form a rotor.

BRIEF DESCRIPTION OF THE DRAWING FIG. 4 is a side view partly in section of a first mold employed in this invention,

FIG. 5 is a front view of the first mold shown in FIG.

FIG. 6 is a front view of a second mold employed in the present invention,

FIG. 7 is a side view partly insection showing the second mold,

tor,

FIG. 9 is a front view showing the winding of a coil wound in the first mold,

FIG. 8 is a longitudinal sectional view of a commutafirst mold showing the winding of a coil provided therein, and r integrally. formed with the shaft and a space 23 corresponding to the pin holes if formed (FIG. 2). Further,

FIGS. 13a to l3c'are side views showing the appearance and dimensions of the flat-type motorof the present invention and other type of conventional motors used in the performance comparison test mentioned in.

this specification. t

PREFERRED'EMBODIMENTS OF THE I INVENTION I Now the present invention will be described hereinbelow with reference to an embodiment thereof.

Referring to FIG, 1, the reference numeral 1 indi-. cates a left housing, 1 indicates a right housing, and 2 and 3 indicate respectively magnets fixed to the interior surfaces thereof. The. numeral 4 shows a rotor fixed to a shaft 5 which in turn is supported by bearings'6 and 6'. The reference numeral 7 indicates a commutator. The numeral8 denotes a brush assembly which com.-

prises a basesupport, brushes, brush holders and press the core cylinder 11 is employed for the purpose of f3? cilitating thecombination of the resin and the shaft 5, and accordingly can be made as a large diameter portion of the shaft 5 or can be omitted if sufficient com bination with the resin is obtainable only with the shaft 5. It will be noted'that it is also possible to set a part of the commutator 7 in each mold together with the shaft without molding the commutator in advance and connecting the ends of the-respective coils thereto so that the parts of thecommutator 7 may be moulded with the springs, the assembly being inserted into the housing'l' 7, which are' integrally molded to each other by use of I aresin l0. I

One of the methods of manufacturing the rotor 4 is shown in'FIGS. 4 to 11. A first'mold l2shown in FIGS.

4 and 5 is'pr'ovided with outer pins13 and inner pins 14 of the same number concentrically arranged at equal intervals. The inner and outer pins are illustrated in FIG. 4 as being integral with the firstmold 12, but is it possible to fix these pins by any known means. The first mold I2 is further provided with resin injection ports 15 and air holes 16. A coil 9 is wound around the outer pins 13 and inner pins 14 as shown in FIGS. 9 and 10 by use of a conductive material 9 (FIG.3). It will be noted that the outer pins 13 may be made oval in shape or comprise combinations of two pins in order that the coil 9 may be wound more widely than that shown in FIG. 9 and the effective magnetic flux may increase.

Then, the shaft 5 is disposed at the center of the first' mold 12 and the terminal end 17 of the coil 9 is connected with a riser 18 of a" commutator 7 as shown in FIG. 8. The commutator 7 is molded and inserted into the shaft 5'in advance. Further, the shaft 5 is provided with a core -cylinder 11 made of iron-inserted thereinto.

Thereafterja second mold 19 asshown in FIGS. 6'and 7 is combined with the first mold 12. The'second mold '19 is provided with outer pinholes 20 and inner pin holes 21 corresponding to the outer pins 13 and inner pins 14 of the first mold 12,. respectively. A space 22 for a rotor is formed with the first and the second molds shaft 5 simultaneously with the molding of thecoils. At the time of winding coil 9 or combining the second mold with the first, it sometimes happens that the insulating cover orshield of the coil comes off, which results in faulty insulation. One of the countermeasures for this trouble is to provide a'projection on the inner surface of the first and second molds so that the coil 9 may belocated at the center of the space before molding and uniform small spaces may be obtained between the side face of the coil and the inner surface of the first "and second molds, whereby the side face of the coil is can be properly determined according to the shapeof the parts of the motor'and the method ofmanufacture. Another embodiment of the method of manufactur ing the armature coil in'accordance with the present invention is shownlin FIG. 12. In this embodiment, the

pins of the first mold 12 comprise radially extending elongated pins 22' serving partly as said outer pins 13 and partly as said'inner pins 14 of the first embodiment. The shaft 5 and the commutator 7 are inserted into the first mold 12 at the time of winding coil. The end of the coil 17 is connected with the riser 18 of the commutator 7 when a conductive material 9 is wound in a coil around the pins 22 to form an armature coil 9. Thereafter, the whole assembly is molded into a unit.

The spaces 23 formed after removing the molds from the molded coil as shown in FIGS. 2 and 3 have an effect of making an air flow when the rotor rotates and results in cooling of the rotor. Further, thespaces 23 can also be used tofill proper material with in order to I balance the rotor.

In accordance with the flat-type motor of the present invention, the magnetic flux makes a closed loop through the magnet 2(N) magnet 3 (S) right housing I" left housing 1 magnet 2. The amount of magnetic flux between the magnet 2 and the magnet 3 influences the performance of the rotor. The amount of magnetic flux 'at this portion decreases as the length of the space between the

magnets

2 and 3 increases.

l2, 19 combined together (FIG. 11)..At this stage, the

thickness of the rotor 4 at the armature coil portion 1 thereof corresponding to a magnet becomes substantially equal to or slightly larger than the thickness .of the coillitself. Then, a resin such as polycarbonate is injected through the resin injection ports 15. When the molds l2 and 19are removed afterwards, a rotor .4 is

Therefore, in ordertoobtain a desired torque, it 'becomesnecessary to reduce the length of the space or increase the numberof conductive members. If the number of conductive members increases copper loss increases and the efficiencyof the 'motor is lowered. Accordingly, it becomes necessary to make thelength of space between the

magnets

2 and 3 as small as possi- .ble. In this invention, a resinous material or the like is rotor and make it fixed integrally with the shaft, and accordingly there is no need to provide an insulating plate for supporting and reinforcing the coil. Based on this, the thickness of the rotor between the

magnets

2 and 3 can be made assmall as'the thickness of the coil. Thus, the length of the space can be made short. Further, by'm'aking the dimension of the

magnets

2 and 3 large in the axial and radial directions it is possible to increase the amount of magnetic flux and increase the output easily.

Furthermore, the thickness of the armature coil can be further decreased by increasing the number of coils to reduce the number of conductive members per coil. However, if the number'of coils is increased, the number of pins and the number of commutator segments increase and accordingly the winding and connecting work of the coils becomes markedly troublesome. Besides, if the number of pins is increased, the diameter of the pins is naturally made small and accordingly the strength of a pin is lowered. At the same time, the operation to make the pins 13, l4 of the first mold l2 mated with the pin holes 20, 21 of the second. mold 19 becomes difficult and the life of the molds-is shortened. The inventors confirmed by experiments-that the motor obtained in accordance with the present invention as mentioned above presented as high efficiency and performance as the conventional print motors and cup-shaped magnet motors. Table l shows the results of the experiments, and FIG. 13 show the shape and dimensions of the motors used in the experiments, wherein FIG. 13a shows a motor made in accordance with the present invention, FIG. 13b shows a print motor, and FIG. 13c showsa cup-shaped motor. The motor shown in FIG. 13a manufactured in accordance with the present invention was made with nineteen coils in which the number of windings of the conductive wire per coil was 13 with a wire of 0.6mm diameter, the outer diameter of the rotor was 106mm,.and the air gap was 5.6mm. The continuous rated life thereof was proved to be longer than 3,000 hours and output of 50W and efficiency of 62 percent were obtained. In the comparison ofthe motors under input of 80W, the efficiency of 62 percentof the motor of this invention was superior to 50 percent of the print motor and 55 percent of the cup-shaped magnet motor. Further, the motor of this invention was proved to be superior even from the viewpoint of temperature rise and noise.

Following reasons can be considered for the high performance of the motor made in accordance with the present invention in comparison with the print motors.

tance between is made large, which results in increase in copper loss and lowering of efficiency. On the other hand, with respect tothe cup-shaped motor, the following reasons can be considered. Since the rotor of the cup-shaped motor is generally made by winding an armature coil around an armature core comprising piled up iron or silicon steel plates, an eddy current loss and hysteresis loss are generated at the time of revolution ofthe armature and the efficiency is lowered. Further, because of its great weight, there is mechanical loss due to inertial and loss of bearing abrasion. To the contrary, in the case of the motor of the present invention tested in the experiments no eddy current or hysteresis loss is made because no magnetic material such as iron or silicon steel at the portion where the rotor intersects with magnetic flux. ln'addition thereto, there is no mechanical loss because the weight of the motor of this invention issmall.

Since, in the flat-type motor in accordance with the present invention, the manufacture of a rotor and integration of the rotor with the shaft and commutator can be carried out markedly easily, the motor can be manufacture at a considerably low cost.

Further, in particular in comparison with the print motor, the motor made in accordance with the present invention has the following advantages. First, since the contact surface of the commutator and brush can be made parallel to the shaft, the processing accuracy of the contact surface of the commutator can be enhanced, andowing to the constant speed of the contact surface of the brush there is little noise. Further, since the peripheral speed of the brush is constant, a good commutation can be expected and accordingly the life is elongated. Besides, the number and diameter of the coil windings can be freely selected and the rotor can be accomodated to various types of molds and process- First, the armature'coils of the print motor are generally made by punching a copper plate, and accordingly there is a limit in the thickness of the plate to be punched. Therefore, the thickness of the coil cannot be made over a predetermined value and the electric resis-.

ing machines. Various dimensions of motors can be easily manufactured using same parts, accordingly.

The motor in accordance with the present invention is applicable not only'to said automobiles but also to servomotors utilizing the feature thereof that the weight of the armature is small. In view of the'feature that the length thereof is small in the axial length and there is generted little noise and the performance is mechanically stable, the motor made in accordance with the present invention is suitable for a tape recorder and makes the size of the tape recorder compact when adapted thereto.

What is claimed is:

1. Method of manufacturing a rotor for a flat-typ motor comprising steps of: 1

winding a wire to make an armature coil in a flat cylindrical space, said flat cylindrical space being defined in part by one surface of a plate-shaped first mold on to which said wire is laid while being fined in part by one surface of a plate-shaped first mold on to which said wire is laid while being wound, said first mold having an interior configuration conforming to an'outer configuration of a first portion of the rotor to be made, providing a shaft extendingalong the longitudinal axis of said cylindrical space and a commutator adjacent to said shaft,

connecting anend of said armature coil with the commutator, combining a second mold with said first mold to form a space between said, first and second molds, said 1 second mold having an interior configuration conforming to the outer configuration of a second portion of the rotor, and filling said space between said first and second molds to surround said armature coil and said shaft at the commutator with a resin material to provide an integrated unit having a predetermined mechanical strength, thereby forming said integrated unit which comprises said armature coil and said shaft.

4. Method of manufacturing a rotor for a flat-type motor comprising steps of: v

arranging a shaft at an opening in the center of a plate-shaped first mold having an interior configuration conforming to the outer configuration ofa first portion of the rotor to be made,

arranging a commutator-adjacent centralopening of said first mold,'.

winding a wire to form an armature coil in a flat cylindrical space, said flat cylindrical space being defined in part by one surface of said first mold on to which said wire is laid while being wound and connecting an end of said wire to the commutator,

combining a second mold with said first mold, said second mold having an interior configuration conforming to the outer configuration of a second'portion of the rotor, and

injecting a resin between the first and second molds to integrallycombine the armature coil and the shaft to form a rotor.

5. Method of manufacturing a rotor for a flat-type motor comprising steps:

inserting a shaft and a commutator into a first mold, said first mold having pins fixed thereto for winding coils therearound and having a surface to define the outer configuration of one side of the rotor to be made, a winding wire about said pins and on to a flat surface of said first mold to form coils and connecting said coils to said commutator to form an armature coil, combining a second mold with said first mold, said second mold having pin holes-to be mated with said pins and having a space define the outer configuration of a second side of the rotor, said first and second molds being further provided with a space to retain the shaft and one of the molds being provided with a space to retain the commutator, and

injecting a resin between the first and second molds to make an integrated unit of said coil, commutator and shaft to form a rotor.

6. Method of manufacturing a rotorfor a flat-type motor as defined in claim 5 wherein a projection of small height is provided on each of the configuration defining surfaces of said first and second molds, whereby the armature coil can be located centrally between the first and second molds.

7. Method of manufacturing a rotor for a flat-type motor comprising the steps of:

forming a relatively flat armature coil by winding wire about pins fixed to a disc-like jig,

positioning a shaft along an axis normal to said flat armature coil,

placing said armature coil and positioned shaft into a mold, and l injecting a resinous material into said mold to integrally moldsaid armature coil and shaft to form a rotor,

wherein said mold is formed of a first mold section and a second mold section, said first and second mold sections forming a cavity therebetween corresponding to the outerconfiguration of the rotor, and said first mold section serving as said disc-like 8. A method according to claim 7, wherein a commutator is fixed to said shaft prior to said positioning step.

9. A method according to claim 7, wherein said shaft is provided with a core cylinder.

10. A method according to claim 7, wherein said first and second mold sections are each formed with at least one projection on respective surfaces forming said cavity to space said armature coil from the surfaces of said first and second mold sections.

Claims

1. Method of manufacturing a rotor for a flat-type motor comprising steps of: winding a wire to make an armature coil in a flat cylindrical space, said flat cylindrical space being defined in part by one surface of a plate-shaped first mold on to which said wire is laid while being wound, said first mold having an interior configuration conforming to an outer configuration of a first portion of the rotor to be made, providing a shaft extending along the longitudinal axis of the cylindrical space, combining a second mold with said first mold to form a space between said first and second molds, said second mold having an interior configuration conforming to the outer configuration of a second portion of the rotor, and filling said space between said first and second molds with a resin material to provide an integrated unit having a predetermined mechanical strength, thereby forming said integrated unit which comprises said armature coil and said shaft.

2. Method of manufacturing a rotor for a flat-type motor as defined in claim 1 wherein a core cylinder is pressed on to the shaft before the shaft is provided in said cylindrical space.

3. Method of manufacturing a rotor for a flat-type motor comprising steps of: winding a wire to make an armature coil in a flat cylindrical space, said flat cylindrical space being defined in part by one surface of a plate-shaped first mold on to which said wire is laid while being wound, said first mold having an interior configuration conforming to an outer configuration of a first portion of the rotor to be made, providing a shaft extending along the longitudinal axis of said cylindrical space and a commutator adjacent to said shaft, connecting an end of said armature coil with the commutator, combining a second mold with said first mold to form a space between said first and second molds, said second mold having an interior configuration conforming to the outer configuration of a second portion of the rotor, and filling said space between said first and second molds to surround said armature coil and said shaft at the commutator with a resin material to provide an integrated unit having a predetermined mechanical strength, thereby forming said integrated unit which comprises said armature coil and said shaft.

4. Method of manufacturing a rotor for a flat-type motor comprising steps of: arranging a shaft at an opening in the center of a plate-shaped first mold having an interior configuration conforming to the outer configuration of a first portion of the rotor to be made, arranging a commutator adjacent central opening of said first mold, winding a wire to form an armature coil in a flat cylindrical space, said flat cylindrical space being defined in part by one surface of said first mold on to which said wire is laid while being wound and connecting an end of said wire to the commutator, combining a second mold with said first mold, said second mold having an interior configuration conforming to the outer configuration of a second portion of the rotor, and injecting a resin between the first and second molds to integrally combine the armature coil and the shaft to form a rotor.

5. Method of manufacturing a rotor for a flat-type motor comprising steps: inserting a shaft and a commutator into a first mold, said first mold having pins fixed thereto for winding coils therearound and having a surface to define the outer configuration of one side of the rotor to be made, winding wire about said pins and on to a flat surface of said first mold to form coils and connecting said coils to said commutator to form an armature coil, combining a second mold wiTh said first mold, said second mold having pin holes to be mated with said pins and having a space define the outer configuration of a second side of the rotor, said first and second molds being further provided with a space to retain the shaft and one of the molds being provided with a space to retain the commutator, and injecting a resin between the first and second molds to make an integrated unit of said coil, commutator and shaft to form a rotor.

6. Method of manufacturing a rotor for a flat-type motor as defined in claim 5 wherein a projection of small height is provided on each of the configuration defining surfaces of said first and second molds, whereby the armature coil can be located centrally between the first and second molds.

7. Method of manufacturing a rotor for a flat-type motor comprising the steps of: forming a relatively flat armature coil by winding wire about pins fixed to a disc-like jig, positioning a shaft along an axis normal to said flat armature coil, placing said armature coil and positioned shaft into a mold, and injecting a resinous material into said mold to integrally mold said armature coil and shaft to form a rotor, wherein said mold is formed of a first mold section and a second mold section, said first and second mold sections forming a cavity therebetween corresponding to the outer configuration of the rotor, and said first mold section serving as said disc-like jig.

8. A method according to claim 7, wherein a commutator is fixed to said shaft prior to said positioning step.