US 3862444 A
This disclosure relates to an electric transmitter for sewing machines and like machines which provides a greater revolution rate than that normally possible solely with an alternating current transmitter in the absence of gearing and like speed multipliers. The electric transmitter utilizes a plurality of motors serially connected with the motors being mounted in a single housing whereby the electric transmitter may be mounted in the normal manner and the clutch-brake thereof may remain of the conventional construction and be mechanically operative.
Claims available in
Description (OCR text may contain errors)
United States Patent 1191 1111 3,862,444
Hale Jan. 21, 1975 SUPER SPEED CLUTCH MOTOR 3,600,616 8/1971 Yokoyama 310/76  Inventor: Arthur N. Hale, Park Rldge, 111. Primary Examiner l' D. Miner  Assignee: Qniop Special Company, Assistant ExaminerRobert J. Hickey Chicago, Ill. Attorney, Agent, or FirmDiller, Brown, Ramik & 22 Filed: Feb. 12, 1973 Wght [2l] Appl. No.: 331,699  ABSTRACT This disclosure relates to an electric transmitter for 52 US. Cl 310/74, 192/18 R, 310/76, Sewing machines and like machines which Provides a 310/115 greater revolution rate than that normally possible  Int. Cl. H02k 7/10, l-lOZk 7/112 solely with an alternating current transmitter in the  Field 61 Search 310/112, 113, 114, 115, absence of gearing and like Speed multipliers- The 310/116, 17 3 7 7 192 electric transmitter utilizes a plurality of motors serially connected with the motors being mounted in a 5 References Cited single housing whereby the electric transmitter may be UNITED STATES PATENTS mounted in the normal manner and the clutch-brake 1983 896 12/1934 B It h 0/115 X thereof may remain of the conventional construction O C 8| 2,745,525 5/1956 Hale 192/18 x and be mechamcany Operanvs' 3,026,459 3/1962 Moore 310/115 UX 5 Claims, 2 Drawing Figures SUPER SPEED CLUTCH MOTOR This invention relates in general to new and useful improvements in electric transmitters for sewing machines and like machines, and more particularly to a super speed electric transmitter which, without utilizing gearing and like speed multiplying mechanism, has a revolution rate which is greater than that heretofore possible with alternating current motors utilizing energy of a given frequency.
BACKGROUND OF THE INVENTION It is conventional to drive a sewing machine utilizing an electric transmitter of the type including a constant revolution rate motor which is operatively connected to an output shaft by means of a clutch-brake device. The motor is free running and the output shaft is fixed against rotation in the non-driving condition of the transmitter. A mechanical actuator is utilized to disengage the brake portion and engage the clutch portion of the clutch-brake.
For efficient and uniform operation of a sewing machine it is desirable to provide a power source which is capable of quick acceleration and deceleration of the machine and which will operate the machine at a sub- .stantially uniform speed throughout a stitch forming operation, regardless of variations in the load in the course of forming a seam. To achieve the latter result, it has been considered desirable to employ an induction motor, and in order to attain a maximum speed this is usually of the two pole type. Such motors operating on 60 cycle alternating current have a maximum theoretical speed of 3,600 R.P.M. but a maximum rated speed of about 3,450 R.P.M.
The importance of quick acceleration and deceleration will be appreciated when it is considered that a sewing machine is subject to very frequent starting and stopping. Only a few seconds are required to form a seam of average length. Therefore, little benefit would be derived from a machine capable of maximum operation at, say, 5,000 R.P.M., if a large portion of the time is consumed in getting up to speed. With the present trend toward higher and higher speeds the importance of rapid acceleration to the normal high speed is accen- I tuated. For good efficiency in the operation of a sewing machine it is desirable to bring the machine to substantially its maximum operating speed within about 1/10 of a second. Even more rapid acceleration is desirable. In general, it has been found that a machine may be gotten up to around 90 percent of its maximum speed within 5 to 30 hundredths of a second, depending upon the machine and its driving means. From this point the machine more gradually increases in speed to its maximum. Factors which enter into the problem of acceleration are the characteristics of the machine itself contributing to inertia, the inertia of the clutch plate and driving pulley of the power unit, the type of belt employed to connect the power unit with the machine, the belt tension, and the like.
To attain machine speeds above 5,000 R.P.M. with present power units, so-called electric transmitters, it has become necessary to increase the size of the motor pulley in relation to the machine pulley. However, this has led to belt slippage, due to the smaller arc of contact with the machine pulley, and has thus increased the length of time required to bring the machine substantially to its maximum speed. This condition becomes quite objectionable when the pulley diameters are such that the machine is operated at more than about one and a half times the speed of the motor.
One solution to the foregoing problem in the past has been by providing suitable gearing between the motor and the flywheel overdriving the flywheel at a rate of about 1.5 to 1. Such arrangement is disclosed in my prior granted US. Pat. No. 2,745,525, granted May 15, 1956, and entitled Electric Transmitter for Sewing machines.
This arrangement, however, has the drawback of the added costs involved, the power loss resulting therefrom and the problem of wearing of the components of the gearing and repair thereof.
Another alternative to the problem is the provision of a frequency changer which will increase the frequency of the current supplied to the electric transmitter. It is impractical to provide an individual machine, such as a sewing machine, with a frequency changer.
It is also known to provide a tandem motor arrangement wherein components of two electric motors are coupled together so as to obtain an output speed equal to a combination of the speed of the two motors. Such motor arrangements have been known for a very long time but in no way utilized with clutch-brake devices for exceeding fast start and stop operations.
SUMMARY OF THE INVENTION In accordance with this invention, a super speed electric transmitter has been invented wherein the customary motor thereof has been replaced by a two-motor unit coupled in series in a mechanically feasible arrangement whereby the speed of the power shaft of the motor of the transmitter is in excess of the normal speed obtainable with the avaiable current frequency.
The principal feature of the invention is the utilization of the tandem motor arrangement in combination with existing transmitter components in a manner wherein the new electric transmitter may be readily mounted to drive a sewing machine in the customary manner and the clutch-brake thereof may remain of the same construction and be mechanically actuated in the normal manner.
Another feature of the invention is the formation of a tandem motor arrangement in an electric transmitter wherein long life of the various components may be realized.
Another feature of the invention is the formation of an electric transmitter which eliminates the necessity of slip-rings or commutator rings for transmitting electrical energy to a rotating component.
With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by a reference to the following detailed description, the appended claims and the several views illustrated in the accompanying drawings:
IN THE DRAWINGS:
FIG. 1 is a longitudinal'sectional view taken through a first form of electric transmitter constructed in accordance with this invention.
FIG. 2 is a longitudinal sectional view similar to FIG. 1 taken through another form of electric transmitter.
Referring now to the drawings in detail, it will be seen that there is illustrated in FIG. 1 a super speed electric transmitter which is generally identified by the numeral 10. The electric transmitter 10 includes a housing which is generally identified by the numeral 11, which housing is provided with support means, generally identified by the numeral 12, for effecting a convenient mounting thereof relative to a sewing machine or other machinery.
The housing 11 may be considered as including a motor section, generally identified by the numeral 13, and a clutch-brake section, generally identified by the numeral 14. Further, the housing 11 is formed of a plurality of individual components which are secured together in any desired manner.
The clutch-brake portion 14 has mounted therein a conventional type of clutch-brake, generally identified by the numeral 15. Such a clutch-brake is disclosed in U.S. Pat. No. 2,739,251 to Ross D. lngalls, granted Mar. 20, 1956.
The housing 11 includes an end cap 16 which supports the clutch-brake unit 15, the end cap 16 being provided with a central tubular support 17 which slidably carries a control sleeve 18.
A stub shaft or output shaft is rotatably journaled within the control sleeve 18 by means of suitable bearings 21, 22. The output shaft 20 projects beyond the control sleeve 18 and has mounted thereon a pulley assembly 23 which will be coupled to the sewing machine or other machine by way of a drive belt.
the inner end of the output shaft 20. opposing the flywheel 24 is a stationary brake member 36 which is suitably carried by the end cap 16.
The clutch disc 25 is normally engaged with the brake member 36 and serves to hold the output shaft 20 and the pulley assembly 23 against rotation. In order that the clutch disc 25 may be engaged with the flywheel 24 to drive the output shaft 20, there is provided a clutch-brake actuating lever 37 which ispivotally mounted on a pin 38 and which lever 37 has a pin 40 which is seated in a circumferential groove 41 formed in the control sleeve 18. It is to be understood that the lever 37 will be spring-loaded in a manner not shown to rotate in a clockwise direction and to constantly urge the control sleeve 18 to the right to hold the clutch disc 25 against the brake member 36. Suitable operator actuated linkage (not shown) will be connected to the lever 37 to effect the rotation thereof in a counterclockwise direction, releasing the brake and engaging the clutch disc 25 with the flywheel 24.
Reference is now made to the motor portion 13 of the housing 11, which motor portion 13 includes a pair of opposed end caps 42 and 43 separated by an intermediate housing member 44. At this time it is to be noted that the end cap 43 has a tubular extension 45 to which the end cap 16 is secured and that the flywheel 24, the clutch disc 25 and the brake member 36 are disposed within the tubular extension 45.
The housing portion 13 has mounted therein a tandem alternating current electric motor assembly generally identified by the numeral 46. The motor assembly 46 includes a solid power shaft 47 which is supported in a tubular sleeve portion 48 of the end cap 42 by means of a bearing 50. The opposite end of the power shaft 47 is supported by a bearing 51 carried by the end cap 43. The power shaft 47 has directly mounted thereon for rotation therewith the flywheel 24.
A tubular shaft 52 is telescoped over the power shaft 47 for a major portion of the length thereof with the left end of the tubular shaft 52 being supported for rotation by a bearing 53 carried by the sleeve portion 48. The right end of the tubular shaft 52 is supported by the power shaft 47 by means of a bearing 54 in a manner to be described hereinafter.
The tandem motor assembly 46 includes a first stage motor, which is preferably of the squirrel-cage induction type and is generally identified by the numeral 55. The motor 55 includes a stator 56 which is carried by the housing portion 44 and is stationarily mounted within the housing 11. The stator 56 includes suitable windings 57 and may be described as a wound element or field.
A rotor or armature 58 in the form of a shorted-bar element is mounted on the tubular shaft 52 for rotation therewith in radial alignment with the stator 56. It is to be understood'that when the windings 57 are energized, the rotor 58 will be driven and the tubular shaft 52 will rotate.
The motor assembly 46 also includes a second stage motor, which is preferably of the squirrel-cage induction type and is generally identified by the numeral 60. The second stage motor 60 includes a rotatable stator 61 which is mounted on a sleeve 62 carried by the tubular shaft 52. It is to be noted that the sleeve 62 is rigidly connected to the tubular shaft 52 and carries the bearing 54 so that the right end of the tubular shaft 52 is supported from the shaft 47 through the sleeve 62.
The stator 61 is also provided with suitable windings 63 which are connected to a power source in a manner to be described hereinafter and thus may be identified as a wound element or field. The stator 61 has radially aligned therewith an outer armature or rotor 64 in the form of a shorted-bar element which is secured in a cantilever manner to the power shaft 47 through a cup shaped support 65.
The tubular shaft 52 and the end cap 42 have mounted thereon a cooperating slip-ring and springloaded brush assembly generally identified by the numeral 66. In the illustrated embodiment of the invention, the slip-ring assembly 66 includes four separate slip-rings. This is due to the fact that the tandem motor assembly 46 utilizes three-phase current and in addition to the three energized leads of a three-phase current power supply, the neutral conductor is also brought out of the housing 11. Suitable leads 67 are connected to the brush contacts of the slip-ring assembly 66 and leads 68 of the windings 57 are also connected to the same contacts. Further leads 70 from the windings 63 extend along the tubular shaft 52 and are connected to respective ones of the slip-rings of the slip-ring assembly 66 for energizing the windings 63.
In the preferred embodiment of the invention, the first stage motor 55 is of a four-pole construction and will run at a speed of about 1,725 rpm when supplied with 60-cycle current. When utilized for use with a sewing machine, it is preferably of a one quarter horsepower capacity and normally will operate on 3 phase 220 volts.
The second stage motor 60 will, of course, be supplied with electrical energy of the same voltage and the same rate frequency as is supplied to the first stage motor 55. In the preferred embodiment of the invention, the second stage motor is equivalent to a one-half horsepower, two-pole motor and, therefore, has a speed of about 3,450 rpm. However, since the stator 61 thereof is not fixed relative to the housing 11, but is fixed to the tubular shaft 52 for rotation therewith, it
will be seen that the relative rotation of the stator 64 with respect to the tubular shaft 52 will be about 3,450 rpm and that the total speed of the power shaft 47 will be the sum of the two speeds, namely, about 5,175 rpm.
Although the first stage motor 55 has been indicated as being a four-pole motor and the second stage motor 60 has been indicated as being a two-pole motor giving a combined speed of about 5,175 rpm for the power shaft 47, other combinations of poles could be designed. For example, based upon 60-cycle current supply, if both the first stage motor and the second stage motor were two-pole motors, then the output speed of the power shaft 47 and the flywheel 24 would be about 6,900 rpm. It is also to be understood that where the frequency of the current is less than 60-cycle, there would be a corresponding reduction in the output speed of the electric transmitter.
It will be apparent that the slip-ring assembly 66 has certain disadvantages such as arcing, wearing, producing dust and dirt, etc. and in certain instances it is advantageous to eliminate such electrical current transferred devices. Accordingly, there has been developed a modification of the electric transmitter 10, the modification being shown in FIG. 2 and the electric transmitter thereof being identified generally by the numeral 110. The electric transmitter 110 includes a housing 111 which has connected thereto a conventional type of support 112 for mounting the transmitter. The housing 111 includes a motor portion 113 and a clutchbrake portion 114. A clutch-brake unit 115, identical to the clutch-brake unit is carried by the housing portion 114 and will not be described in further detail except to state that it cooperates with a flywheel 124 which is carried by a tandem motor assembly 146 carried by the motor portion 113 of the housing 111.
The tandem motor assembly 146 includes a rigid power shaft 147 -which has the left end thereof journaled in a bearing 150 carried by a tubular portion 148 of one end cap 142 of the housing 1 11. The right hand end of the shaft 147 is rotatably journaled in a bearing 151 carried by a second end cap 143 of the housing 111. At this time it is pointed out that the housing 111 also includes separate intermediate portions 144, 144a and 144b disposed between the end caps 142 and 143.
A tubular shaft 152 is telescoped over the power shaft 147 for the major portion of its length with the left end of the tubular shaft 152 being rotatably supported by a bearing 153 carried by the end cap 142. The right end of the tubular shaft 152 is rotatably supported through a bearing 154 carried by the power shaft 147 in a manner to be described hereinafter.
The tandem motor 146 also includes a first stage motor 155 which is preferably of the squirrel-cage induction type and has an outer stator 156 fixedly carried by the housing portion 144. The stator 156 includes windings 157 and may be described as a wound element or field.
The first stage motor 155 also includes an armature or rotor 158 which is radially aligned with the stator 156 and which is rigidly secured to the tubular shaft 152 for rotation therewith, the rotor being in the form of a shorted-bar element. It is to be understood that the first stage motor 155 will drive the tubular shaft 152.
A second stage motor, generally identified by the numeral 160, of the tandem motor assembly 146, is mounted generally within the end cap 143. The second stage motor 160 is also of the squirrel-cage induction type and includes a stator 161 which is fixedly mounted on a mounting sleeve 162 which, in turn, is fixedly mounted on the tubular shaft 152 for rotation therewith. The bearing 154 supporting the right end of the tubular shaft 152 is carried by the sleeve 162 with the result that the sleeve 162 supports the right end of the tubular shaft 152.
It is to be understood that the stator 161 includes windings 163 and thus may be identified as a wound element or field. It is also to be understood that the second stage motor includes a rotor 164 which is radially aligned with the stator 161 and which is carried by a cup-shaped support 165. The cup-shaped support 165, in turn, is fixedly secured to the power shaft 147 for driving the same. The flywheel 124 is also mounted on the power shaft 147 to be driven thereby.
As stated above, the electric transmitter 111 is constructed so that the tandem motor assembly thereof may have the necessary electrical power delivered to the rotating components thereof without the use of a slip-ring assembly or other rotating electrical energy transmitter which requires brushes and collector rings. To this end, the second stage motor 160 is spaced longitudinally from the first stage motor 155 sufficiently to accommodate a transformer generally identified by the numeral 172. The transformer 172 includes a stationary field magnet 173 which is carried by the housing portion 144b and which is provided with suitable windings 174. Carried by the tubular shaft 152 for rotation therewith and radially aligned with the stationary field magnet is an armature having suitable windings 176. It is to be understood that the stationary field magnet 173 and its associated winding 174 form the primary member of the transformer 172 and that the armature 175 and its associated winding 176 form the secondary member of the transformer 172. The primary and secondary members of the transformer form, purely electrically, nothing more than the transformer of the known type. The current inducted into the windings 176 is supplied by suitable conductors 177 to the windings 163 of the stator 161.
It is to be noted that the intermediate housing portion 144a has aligned therewith a junction box 178 which is provided with a fitting 180 through which a power supply 181 enters into the junction box 178. A suitable junction block 182 will be mounted in the junction box 178 and leads 183 and 184 coupled to the supply line 181 at the junction block 182 are coupled to the windings 157 and 174, respectively, to energize them.
It is to be understood that the first stage motor 155 and the second stage motor 160 may be of the same construction as that set forth with respect to the motors 55, 60 including the various alternatives as outlined above. Accordingly, no further description of the tandem motor assembly 46 is required. In a like manner, the clutch-brake 115 will perform in the same manner as that described with respect to the clutch-brake 15.
Although only two preferred embodiments of the electric transmitter have been specifically illustrated and described herein, it is to be understood that minor variations may be made in the electric transmitter construction without departing from the spirit and scope of the invention, as defined by the appended claims.
1. A high speed clutch-brake drive for intermittently driving a serving machine head, said drive comprising a fixed housing having means for mounting the same in constantly rotating induction motors mounted within said housing, said motors having rotating components including a power shaft rotatably journalled relative to said housing, coupling means coupling rotating components of said motors for continuously driving said power shaft at a speed corresponding to the total of the speeds of said two motors and in excess of synchronous speed, a flywheel secured to said power shaft for continuous rotation therewith, an output shaft rotatably supported by said housing in axial alignment with said power shaft, a drive pulley carried by said output shaft for driving a sewing machine head, and a clutch-brake device carried by said housing for selectively coupling said output shaft to said flywheel for rotation therewith and for preventing rotation of said output shaft, said clutch-brake device including a fixed friction face spaced from and opposing said flywheel, a clutch disc coupled to said output shaft and having two friction engaging faces, said clutch disc being positioned between said flywheel and said fixed friction face and means mounting said clutch disc for selective engagement with said flywheel for rotation therewith and said fixed friction face for braking said clutch disc.
2. The drive of claim 1 wherein each of said motors includes a field and a rotor, and said coupling means including means coupling a field of one motor to a rotor of the other motor for rotation in unison.
3. The drive of claim 1 wherein each of said motors includes a field and a rotor, and said coupling means including means coupling a field of one motor to a rotor of the other motor for rotation in unison, the field of the other motor being fixedly secured to said housing and the rotor of said one motor being coupled to said power shaft.
4. The drive of claim 1 wherein said induction motors are squirrel-cage motors, and said rotors are shortedbar rotors.
S. The drive of claim 1 wherein each of said motors includes a field and a rotor, and said coupling means including a tubular shaft disposed coaxially with said power shaft and coupling a field of one motor to a rotor of the other motor for rotation in unison.
UNITED STATES PATENT @FFIQE CERTIFICATE 6F QQBRECTION Patent N0, Datgd January 21,
Inventor-(s) Arthur N. Hale It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
On the Mostract Page, under Assignees, read "Union Special Company" as em Unicm Special Corperatinn Signed and sealed this 15th day of July 1.975.
(I. MARSHALL DANN RUTH C. MASON Cemmissioner of Patents Attesting Officer and Trademarks "UNITED STATES PATENT @FFICE @ERTIFICATE @LF @QRHECETWN Patent No. 3,862,444 Dated January 21, 1975 Inventor g Arthur Ne Hale It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
On the Abstract Page, under Assignee, read "Union Special Company" as Union Special Corporation Signed and sealed this 15th day of July 1975.
(SEAL) Attest c MARSHALL DANN RUTH C. MASON Commissioner 0f Patents Attesting Officer and Trademarks