CA1119651A - Integral spring rotor punchings for induction motor - Google Patents
Integral spring rotor punchings for induction motorInfo
- Publication number
- CA1119651A CA1119651A CA000328380A CA328380A CA1119651A CA 1119651 A CA1119651 A CA 1119651A CA 000328380 A CA000328380 A CA 000328380A CA 328380 A CA328380 A CA 328380A CA 1119651 A CA1119651 A CA 1119651A
- Authority
- CA
- Canada
- Prior art keywords
- punchings
- conductor
- rotor
- openings
- induction motor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K17/00—Asynchronous induction motors; Asynchronous induction generators
- H02K17/02—Asynchronous induction motors
- H02K17/16—Asynchronous induction motors having rotors with internally short-circuited windings, e.g. cage rotors
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Iron Core Of Rotating Electric Machines (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A rotor for an induction motor is made of a stack of punchings forming the body of the rotor and including a set of main punchings with integral spring punchings spaced apart in the stack of punchings. The main punchings have conductor receiving slots which preferably are closed at the periphery and have a portion at the radially inward end which extends deeper than is necessary to accommodate a conductor.
The integral spring punchings have conductor receiving slots which align with those of the main punchings, and they also have a portion at the radially inward end which extends deeper than necessary to accommodate the conductor. The integral spring punchings have a projecting integral tab at the inner extent of the slot. This spring tab is deflected when the conductor is installed and provides on the conductor an outwardly directed spring force to reduce vibration and rattling.
A rotor for an induction motor is made of a stack of punchings forming the body of the rotor and including a set of main punchings with integral spring punchings spaced apart in the stack of punchings. The main punchings have conductor receiving slots which preferably are closed at the periphery and have a portion at the radially inward end which extends deeper than is necessary to accommodate a conductor.
The integral spring punchings have conductor receiving slots which align with those of the main punchings, and they also have a portion at the radially inward end which extends deeper than necessary to accommodate the conductor. The integral spring punchings have a projecting integral tab at the inner extent of the slot. This spring tab is deflected when the conductor is installed and provides on the conductor an outwardly directed spring force to reduce vibration and rattling.
Description
9~5~
This invention relates to induction motors, and in particular it relates to rotor punchings for an induction motor.
In the manufacture of induction motors, a number of generally circular, similar punchings from sheet metal are stacked together to form a rotor core.
Each punching or lamination has a plurality of slots spaced apart around the periphery and when the punchings are stacked with the slots aligned the slots are ready to receive a conductor. When the conductor is placed in the slot, the fit must be such that there is no vibration or rattling.
One way of ensuring a good fit is disclosed in ~anadian Patent No. 251 776 - Lindquist, issued July 14, 1925. This patent describes a corrugated strip of resilient or elastic material that is placed in the bottom of the slot usually after the conductor has been inserted. This strip acts as a spring which presses the conductor outwardly to prevent rattling and vibration.
The installation of a separate spring at the bottom of each slot complicates the assembly of the rotor. It involves additional steps and is not always easy to plac:e in position. In addition, it is not particularly suitable for squirrel cage induction motors.
~ ,, ~ / _ ' 36S~
Case 2661 In a squirrel cage type motor the slots are frequently closed at the outer periphery of the punchings, that is, the slot frequently terminates just inside the periphery. The conductor bar is driven through the slot from an end of the s-tack of laminations or punchings. The bar and the slot must be dimensioned to provide a correct fit. If the bar is of a size that makes a fit that is not tight enough, the bar will rattle or some means must be provided to take up the extra space. If the bar is of a size that makes a fit that is too tight, the bar cannot be driven into the slot with reasonable assembly forces.
In the assembly of squirrel cage rotors, it is known to adjust the ~it of a particular bar or bars by broaching the slot or by machining the bars. This complicates and slows the assembly operation.
The present invention is concerned with simplifying the construction of a squirrel cage rotor for an induction motor and for providing for easier assembly. The invention permits more clearance between the slot walls and the conductor bar during assembly, and prevents rattling by the use of a spring force.
The spring force is not applied by a separate spring which requires individual installation in each slot.
According to the invention, the spring force is provided by a special punching which has a spring element projecting into the space to be occupied by the bar. That is, the spring is an integral part of ~he punching. The special punching is interleaved with the regular punchings at intervals in the stack.
When the conductor bar is driven through the slot it deflects these spring elements or spring tabs which then exert an outwardly directed force on the bar.
Assembly using the special punchings is faster, it avoids any final broaching or machining steps, and it 9GS~iL
Case 2661 requires no additional steps.
It is therefore a feature of the invention to provide a punching ~o be used in assembly which provides a spring force on each conductor extruding through the aligned openings or slots.
Accordingly the present invention provides a rotor for an induction motor, comprising a stack of punchings including first and second punchings, forming the body of said rotor, said first punchings having a plurality of conductor-receiving openings spaced around said rotor, and being arranged with said conductor-receiving openings in alignment, said first punchings including at each set of aligned openings means to restrain conductors against radially outward movement, said second punchings being spaced apart in said stack by at least several first punchings, said second punchings having the same numbex of conductor-receiving openings as said first punchings and being arranged in said stack with the openings in alignment, and a conductor extending through each set of aligned ; openings, said openings of said second punchings having a portion extending radially inwardly farther than necessary to receive a respective conductor and having at the inward extent an outwardly projecting integral tab engaging said respective conductor, said tab being deflected when said conductor is inserted through said aligned openings to provide on the conductor an outwardly directed spring force, said stack of punchings being provided with means to permit deflection of said tabs.
The invention will be described with reference to the acco]mpanying drawings, in which Figure 1 is a plan view of a part of a punching which is usl_d to form the body of a rotor according to the invention, and .
j,5~
Case 2661 Figure 2 is a plan v:iew of part of a special punching incorporating a spring according to one form of the invention, Figure 3 is an elevat:ion in section of part of a rotor showing a stack of punchings including those of Figure 1 and 2.
Referring to Figure 1, a portion of a punching 10 is shown. Punchings are normally made from sheet steel in a manner well known :in the art. The punching 10 has a main portion 11 with projeeting arms or spokes 12 which define the edges 14 of a slot 15. The slot 15 is enelosed, that is the edges 1~ defining the outermost point 16 are very slightly spaeed from the periphery 17 of punehing 10. This is eertainly not essential but it is common for a squirrel cage rotor.
If punchings 11 are used where the slot is not closed but is open, then some means, sueh as eaps or wedges engaging grooves in the edges 14 at the periphery, or sueh as conduetor-retaining peripheral projeetions, must be provided to restrain eonduetors in the slot against radially outward movement.
A broken line 18 indicates generally the position in slot 15 the bar will oeeupy after it is installed. The slot 15 is shown as having a portion slightly deeper than the bar whieh it reeeives. Th~s is to provide an open region 19 to accommodate movement of a spring as will beeome elear in the following description~ The slot 15 preferab~y has lips 27 whieh engage the bottom edges of a conduetor to restrain it against inward movement, and to serve as a guide during installation.
Referring now to Figure 2, a portion of punehing 20 is shown. This punehing would normally be made from the same material as punehing 10 but it may be made from other materials as it oeeupies only ~.
.
- -965~
Case 2661 a small volume of total rotor volume. For example, it may be desirable to make punching 20 ~rom a m~terial with better spring quali-ties.
Punching 20 has a main portion 21 with projec-ting arms or spokes 22 which define lateral edges 23of slot 24. The slot 24 is also punched deeper than necessary to accommodate a conductor bar, but it has an integral tab or projection 25 which acts as a spring. A broken line 26 inclicates generally the position in slot 24 the bar will occupy after it is installed. It will be seen that the projecting tab or spring projection 25 extends into the region the bar will occupy after it is installed.
It will be apparent that punching 21, which is shown with an open slot 24 (i.e. open at its outer ena~, could have a closed slot similar to slot 15 of punching 11.
Referring now to Figure 3, a sectional view of part of a rotor is shown with punchings 10 stacked together, and at intervals in the stack a punching 20. A conductor bar 28 is installed and the projecting integral tab 25 of each punching 20 is deformed by the bar 28 during installation of the bar. The spring tabs 25 are bent into the open region 19. The deformed spring tabs 25 apply an outwardly directed force to keep the bar 28 firmly in the slot comprising slots 15 and 24 of punchings 10 and 20 respectively.
The spacing between punchings 20 is not critical and can be determined for a particular design of squirrel cage motor. If more spring force is reguired, th~ spacing between adjacent punchings 20 can be decreased.
If ithe rotor is provided with ventilating passages at intervals therethrough, it may be convenient to position a punching 20 adjacent the ,, , .
-L965~L
Case 2661 ventilating passage. In such an arrangement the projecting spring tab 25 can be deflected into the ventilating passage as the conductor bar is installed and the slots 15 in punchings 10 need not be any deeper than the bar. That is, there is no need to provide space at the hottom of slot 15 to provide room for deflection of spring tab 25 as the room is available in the ventilating passage.
It will be apparent that in the absence of ventilating passages, space must be provided at the bottom of slot 15 for deflection of spring projection 25, but this space is only required for several punchings adjacent to each spring tab 25, that is adjacent to each punching 20. Consequently an alternative arrangement might have several punchings 10 adjacent each punching 20 with intermediate space filled with normal punchings where slot 15 is only deep enough to accommodate a bar.
Other variations and alternatives may become apparent to those s~illed in the art.
.
.: - , . . . .
.
,
This invention relates to induction motors, and in particular it relates to rotor punchings for an induction motor.
In the manufacture of induction motors, a number of generally circular, similar punchings from sheet metal are stacked together to form a rotor core.
Each punching or lamination has a plurality of slots spaced apart around the periphery and when the punchings are stacked with the slots aligned the slots are ready to receive a conductor. When the conductor is placed in the slot, the fit must be such that there is no vibration or rattling.
One way of ensuring a good fit is disclosed in ~anadian Patent No. 251 776 - Lindquist, issued July 14, 1925. This patent describes a corrugated strip of resilient or elastic material that is placed in the bottom of the slot usually after the conductor has been inserted. This strip acts as a spring which presses the conductor outwardly to prevent rattling and vibration.
The installation of a separate spring at the bottom of each slot complicates the assembly of the rotor. It involves additional steps and is not always easy to plac:e in position. In addition, it is not particularly suitable for squirrel cage induction motors.
~ ,, ~ / _ ' 36S~
Case 2661 In a squirrel cage type motor the slots are frequently closed at the outer periphery of the punchings, that is, the slot frequently terminates just inside the periphery. The conductor bar is driven through the slot from an end of the s-tack of laminations or punchings. The bar and the slot must be dimensioned to provide a correct fit. If the bar is of a size that makes a fit that is not tight enough, the bar will rattle or some means must be provided to take up the extra space. If the bar is of a size that makes a fit that is too tight, the bar cannot be driven into the slot with reasonable assembly forces.
In the assembly of squirrel cage rotors, it is known to adjust the ~it of a particular bar or bars by broaching the slot or by machining the bars. This complicates and slows the assembly operation.
The present invention is concerned with simplifying the construction of a squirrel cage rotor for an induction motor and for providing for easier assembly. The invention permits more clearance between the slot walls and the conductor bar during assembly, and prevents rattling by the use of a spring force.
The spring force is not applied by a separate spring which requires individual installation in each slot.
According to the invention, the spring force is provided by a special punching which has a spring element projecting into the space to be occupied by the bar. That is, the spring is an integral part of ~he punching. The special punching is interleaved with the regular punchings at intervals in the stack.
When the conductor bar is driven through the slot it deflects these spring elements or spring tabs which then exert an outwardly directed force on the bar.
Assembly using the special punchings is faster, it avoids any final broaching or machining steps, and it 9GS~iL
Case 2661 requires no additional steps.
It is therefore a feature of the invention to provide a punching ~o be used in assembly which provides a spring force on each conductor extruding through the aligned openings or slots.
Accordingly the present invention provides a rotor for an induction motor, comprising a stack of punchings including first and second punchings, forming the body of said rotor, said first punchings having a plurality of conductor-receiving openings spaced around said rotor, and being arranged with said conductor-receiving openings in alignment, said first punchings including at each set of aligned openings means to restrain conductors against radially outward movement, said second punchings being spaced apart in said stack by at least several first punchings, said second punchings having the same numbex of conductor-receiving openings as said first punchings and being arranged in said stack with the openings in alignment, and a conductor extending through each set of aligned ; openings, said openings of said second punchings having a portion extending radially inwardly farther than necessary to receive a respective conductor and having at the inward extent an outwardly projecting integral tab engaging said respective conductor, said tab being deflected when said conductor is inserted through said aligned openings to provide on the conductor an outwardly directed spring force, said stack of punchings being provided with means to permit deflection of said tabs.
The invention will be described with reference to the acco]mpanying drawings, in which Figure 1 is a plan view of a part of a punching which is usl_d to form the body of a rotor according to the invention, and .
j,5~
Case 2661 Figure 2 is a plan v:iew of part of a special punching incorporating a spring according to one form of the invention, Figure 3 is an elevat:ion in section of part of a rotor showing a stack of punchings including those of Figure 1 and 2.
Referring to Figure 1, a portion of a punching 10 is shown. Punchings are normally made from sheet steel in a manner well known :in the art. The punching 10 has a main portion 11 with projeeting arms or spokes 12 which define the edges 14 of a slot 15. The slot 15 is enelosed, that is the edges 1~ defining the outermost point 16 are very slightly spaeed from the periphery 17 of punehing 10. This is eertainly not essential but it is common for a squirrel cage rotor.
If punchings 11 are used where the slot is not closed but is open, then some means, sueh as eaps or wedges engaging grooves in the edges 14 at the periphery, or sueh as conduetor-retaining peripheral projeetions, must be provided to restrain eonduetors in the slot against radially outward movement.
A broken line 18 indicates generally the position in slot 15 the bar will oeeupy after it is installed. The slot 15 is shown as having a portion slightly deeper than the bar whieh it reeeives. Th~s is to provide an open region 19 to accommodate movement of a spring as will beeome elear in the following description~ The slot 15 preferab~y has lips 27 whieh engage the bottom edges of a conduetor to restrain it against inward movement, and to serve as a guide during installation.
Referring now to Figure 2, a portion of punehing 20 is shown. This punehing would normally be made from the same material as punehing 10 but it may be made from other materials as it oeeupies only ~.
.
- -965~
Case 2661 a small volume of total rotor volume. For example, it may be desirable to make punching 20 ~rom a m~terial with better spring quali-ties.
Punching 20 has a main portion 21 with projec-ting arms or spokes 22 which define lateral edges 23of slot 24. The slot 24 is also punched deeper than necessary to accommodate a conductor bar, but it has an integral tab or projection 25 which acts as a spring. A broken line 26 inclicates generally the position in slot 24 the bar will occupy after it is installed. It will be seen that the projecting tab or spring projection 25 extends into the region the bar will occupy after it is installed.
It will be apparent that punching 21, which is shown with an open slot 24 (i.e. open at its outer ena~, could have a closed slot similar to slot 15 of punching 11.
Referring now to Figure 3, a sectional view of part of a rotor is shown with punchings 10 stacked together, and at intervals in the stack a punching 20. A conductor bar 28 is installed and the projecting integral tab 25 of each punching 20 is deformed by the bar 28 during installation of the bar. The spring tabs 25 are bent into the open region 19. The deformed spring tabs 25 apply an outwardly directed force to keep the bar 28 firmly in the slot comprising slots 15 and 24 of punchings 10 and 20 respectively.
The spacing between punchings 20 is not critical and can be determined for a particular design of squirrel cage motor. If more spring force is reguired, th~ spacing between adjacent punchings 20 can be decreased.
If ithe rotor is provided with ventilating passages at intervals therethrough, it may be convenient to position a punching 20 adjacent the ,, , .
-L965~L
Case 2661 ventilating passage. In such an arrangement the projecting spring tab 25 can be deflected into the ventilating passage as the conductor bar is installed and the slots 15 in punchings 10 need not be any deeper than the bar. That is, there is no need to provide space at the hottom of slot 15 to provide room for deflection of spring tab 25 as the room is available in the ventilating passage.
It will be apparent that in the absence of ventilating passages, space must be provided at the bottom of slot 15 for deflection of spring projection 25, but this space is only required for several punchings adjacent to each spring tab 25, that is adjacent to each punching 20. Consequently an alternative arrangement might have several punchings 10 adjacent each punching 20 with intermediate space filled with normal punchings where slot 15 is only deep enough to accommodate a bar.
Other variations and alternatives may become apparent to those s~illed in the art.
.
.: - , . . . .
.
,
Claims (7)
1. A rotor for an induction motor, comprising a stack of punchings including first and second punchings, forming the body of said rotor, said first punchings having a plurality of conductor-receiving openings spaced around said rotor, and being arranged with said conductor-receiving openings in alignment, said first punchings including at each set of aligned openings means to restrain conductors against radially outward movement, said second punchings being spaced apart in said stack by at least several first punchings, said second punchings having the same number of conductor-receiving openings as said first punchings and being arranged in said stack with the openings in alignment, and a conductor extending through each set of aligned openings, said openings of said second punchings having a portion extending radially inwardly farther than necessary to receive a respective conductor and having at the inward extent an outwardly projecting integral tab engaging said respective conductor, said tab being deflected when said conductor is inserted through said aligned openings to provide on the conductor an outwardly directed spring force, said stack of punchings being provided with.
means to permit deflection of said tabs.
means to permit deflection of said tabs.
2. A rotor for an induction motor as defined in claim 1 in which said conductor-receiving openings of said first punchings are adjacent the periphery and are closed by the material of the punching.
Case 2661
Case 2661
3. A rotor for an induction motor as defined in claim 1 in which said conductor-receiving openings of said second punchings extend to the periphery of the second punching.
4. A rotor for an induction motor as defined in claim 1, 2 or 3 in which said conductor is a conductor bar.
5. A rotor for an induction motor as defined in claim 1 in which said means to permit deflection of said tab comprises said openings of said first punchings extending radially inwardly farther than necessary to receive a conductor therein and of a size greater than the size of said tab.
6. A rotor for an induction motor as defined in claim 5 in which said openings of said first punchings have lips on either side at the inner extent of said conductor to restrain said conductor against radially inward movement.
7. A rotor for a squirrel cage induction motor, comprising a sleek of punchings including first and second punchings forming the body of said rotor and having a plurality of aligned conductor bar receiving openings therein spaced around the body of said rotor adjacent the periphery and including restraining means for restraining conductor bars against radially outward movement, and a conductor bar extending through each of said aligned openings, said second punchings being spaced apart in said sleek of punchings and each having the conductor bar receiving opening extending radially inwardly farther than necessary to accommodate said conductor bar and having at the inward portion thereof an Case 2661
7. A rotor for a squirrel cage induction motor, comprising a sleek of punchings including first and second punchings forming the body of said rotor and having a plurality of aligned conductor bar receiving openings therein spaced around the body of said rotor adjacent the periphery and including restraining means for restraining conductor bars against radially outward movement, and a conductor bar extending through each of said aligned openings, said second punchings being spaced apart in said sleek of punchings and each having the conductor bar receiving opening extending radially inwardly farther than necessary to accommodate said conductor bar and having at the inward portion thereof an Case 2661
Claim 7 continued:
outwardly projecting integral tab for engaging said conductor bar, said tabs being deflected when said conductor bar is installed in the aligned openings and providing an outwardly directed spring force, said stack of punchings being provided with means permitting deflection of said tabs.
outwardly projecting integral tab for engaging said conductor bar, said tabs being deflected when said conductor bar is installed in the aligned openings and providing an outwardly directed spring force, said stack of punchings being provided with means permitting deflection of said tabs.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000328380A CA1119651A (en) | 1979-05-25 | 1979-05-25 | Integral spring rotor punchings for induction motor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000328380A CA1119651A (en) | 1979-05-25 | 1979-05-25 | Integral spring rotor punchings for induction motor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1119651A true CA1119651A (en) | 1982-03-09 |
Family
ID=4114293
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000328380A Expired CA1119651A (en) | 1979-05-25 | 1979-05-25 | Integral spring rotor punchings for induction motor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1119651A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20130187512A1 (en) * | 2010-09-30 | 2013-07-25 | Siemens Aktiengesellschaft | Squirrel-cage rotor |
| US20150295483A1 (en) * | 2012-10-30 | 2015-10-15 | Siemens Aktiengesellschaft | Cage rotor comprising a deformable bearing |
-
1979
- 1979-05-25 CA CA000328380A patent/CA1119651A/en not_active Expired
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20130187512A1 (en) * | 2010-09-30 | 2013-07-25 | Siemens Aktiengesellschaft | Squirrel-cage rotor |
| US10700582B2 (en) * | 2010-09-30 | 2020-06-30 | Siemens Aktiengesellschaft | Rotor bar for squirrel-cage rotor, and squirrel-cage rotor provided with rotor bar |
| US20150295483A1 (en) * | 2012-10-30 | 2015-10-15 | Siemens Aktiengesellschaft | Cage rotor comprising a deformable bearing |
| US10476361B2 (en) * | 2012-10-30 | 2019-11-12 | Siemens Aktiengesellschaft | Cage rotor comprising a deformable bearing |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |