CA2285837C - Improved two-piece flexplate design - Google Patents
Improved two-piece flexplate design Download PDFInfo
- Publication number
- CA2285837C CA2285837C CA 2285837 CA2285837A CA2285837C CA 2285837 C CA2285837 C CA 2285837C CA 2285837 CA2285837 CA 2285837 CA 2285837 A CA2285837 A CA 2285837A CA 2285837 C CA2285837 C CA 2285837C
- Authority
- CA
- Canada
- Prior art keywords
- disc
- flywheel
- flexplate
- ring gear
- weld
- 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 - Fee Related
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F15/00—Suppression of vibrations in systems; Means or arrangements for avoiding or reducing out-of-balance forces, e.g. due to motion
- F16F15/30—Flywheels
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Aviation & Aerospace Engineering (AREA)
- Mechanical Engineering (AREA)
- Butt Welding And Welding Of Specific Article (AREA)
- Gears, Cams (AREA)
Abstract
In a flexplate flywheel, the intermittent weld structure between the inner plate and the associated ring gear extends away from the outer ring and towards the inner diameter of the plate to substantially increase the interface length and reduce the level of stress concentrations at the weld tip, thereby improving fatigue life and stiffness of the flexplate.
Description
~.., _~, .,. .. . ..... ,,..,,..,a.,,... ~,,,,_ BPROVED T'VVO-PICECE FLEKpLATE DESIGN
TECHNICAL FIELD
The subject invention relates to flywheels for automotive engines and the Ixlce. More particularly, the invention relates to a means for improving the weld structure between the outer ring gear and the iu=r plate or disc.
BACKGRI)'[)'ND OF'f'HE IIWENTION
The startix-g mechanism for an intemal combustion engine used i,x an automobile comprises au electric starting motor which is enpged via a pinion gear to mating tecth on a flywheel, whieh in tu.rn is attached to the crankshaft of the engine. When the electric starting motor receives eloctrical current from a battery, the teeth of the pinioo. gear on the end of the motor armature shaft are broug'ht into sngagemcnt with the teeth of the flywheel, thereby causing the crankshaft to rotate.
Once the engine has started, the pinian gear of the starting motor is automat.ically disengaged, and the flywheel continues to rotate due to the movement of the crankshaft.
There are two di#ferent types of flywheels used with automotive engines or the like.
The first type is used witlt a manual transmission, a-nd usually comprises a large cast metal assembly, which provides mounting nleans for the bell housing and clutch ofthe tnnamission, and also provides inertia to keep the enginc frozn stalling out. Tlus type of casting usually has a ring gear slmunk on to its outer lU/1'L/dd 1tl:5lf !'A1L GUWLINGB t~JUU6 circumference. The teeth on the ring gear engage the teeth on the starting motor pinion gear. The second type of flywhoel is used with an auto,rnadc transmission and usually comprises a relatively thin metal stannping, called a flexplate, having a ring gear attached, usually by welding, to the oater circuntferance thereof.
Although this type of flywheel is not really used to provide any inertia for the engine, a torque converter is usually moiinted thereon as part of the transmission. The preseiit invention relates primarily to this second type of flywheel, although it is contemplated that the basic idea of this invention might also be applied to the first type of flywheel dsscribed above with appropriate modifications. The tcrm "flywheel" is used herein as including both types.
The pzior art relating to flexplate engine flywheels contains numerous refetences to two piecQ flexplate designs whereby a thin ann,alar ring g=
is fixed by welding to an irm.er plate or diso. One such prior art arrarigement which has been used commercially in automobiles fox connecting the engine with a transmission is shown in Figure 1.
In this Figure, ntuneral 10 indicat:e,ss the prior art flywheel which comprises a circular disc 11 of rotatably stiff but axially flexible relatively thin sheet metal. The disc 11 is of gerterally constant axial ttxiclmess although variable thaclozess discs can also be used. The disc 11 has a generally flat outer amulus 12 contacted with a slightly dished central portion 14 having a central $uide opening 15 surrounded by a plurality of smaller openings 16 for attac.lting the disc l t to a flanged end 18 of an engine crankshaft 19. The degree of dishing is optional and depends primarily upon the space available between the crankshaft 19 and an associated transmission input member such as a fluid coupling 20.
Beyond the outer annulus 12, the disc 11 has a short axial flange 21 to which is intermittently welded at 22 a steel ring gear 23 having outwardly facing teeth 24 adapted to be engaged by a starter drive gear (not shown) for starting the engine. Some prior art arrangements omit the flange 21 and weld the ring gear directly to the flat outer annulus 12 of the disc. Welding is usually intermittent, although US Patent No. 5,323,665 discloses a continuous weld bead to reduce starting induced vibrations.
During operation, stress concentrations at the root of the weld initiate cracks in the plate, as illustrated in Figure 2. Typically, the fatigue crack 25 follows around the base of the weld until the plate breaks free of the outer ring gear.
Catastrophic failure of the flexplate then occurs. To extend fatigue life, the usual approach involves adding an increasing number of spot welds, or a continuous weld bead as disclosed in US Patent No. 5,323,665, to retain the outer ring gear to the inner plate.
TECHNICAL FIELD
The subject invention relates to flywheels for automotive engines and the Ixlce. More particularly, the invention relates to a means for improving the weld structure between the outer ring gear and the iu=r plate or disc.
BACKGRI)'[)'ND OF'f'HE IIWENTION
The startix-g mechanism for an intemal combustion engine used i,x an automobile comprises au electric starting motor which is enpged via a pinion gear to mating tecth on a flywheel, whieh in tu.rn is attached to the crankshaft of the engine. When the electric starting motor receives eloctrical current from a battery, the teeth of the pinioo. gear on the end of the motor armature shaft are broug'ht into sngagemcnt with the teeth of the flywheel, thereby causing the crankshaft to rotate.
Once the engine has started, the pinian gear of the starting motor is automat.ically disengaged, and the flywheel continues to rotate due to the movement of the crankshaft.
There are two di#ferent types of flywheels used with automotive engines or the like.
The first type is used witlt a manual transmission, a-nd usually comprises a large cast metal assembly, which provides mounting nleans for the bell housing and clutch ofthe tnnamission, and also provides inertia to keep the enginc frozn stalling out. Tlus type of casting usually has a ring gear slmunk on to its outer lU/1'L/dd 1tl:5lf !'A1L GUWLINGB t~JUU6 circumference. The teeth on the ring gear engage the teeth on the starting motor pinion gear. The second type of flywhoel is used with an auto,rnadc transmission and usually comprises a relatively thin metal stannping, called a flexplate, having a ring gear attached, usually by welding, to the oater circuntferance thereof.
Although this type of flywheel is not really used to provide any inertia for the engine, a torque converter is usually moiinted thereon as part of the transmission. The preseiit invention relates primarily to this second type of flywheel, although it is contemplated that the basic idea of this invention might also be applied to the first type of flywheel dsscribed above with appropriate modifications. The tcrm "flywheel" is used herein as including both types.
The pzior art relating to flexplate engine flywheels contains numerous refetences to two piecQ flexplate designs whereby a thin ann,alar ring g=
is fixed by welding to an irm.er plate or diso. One such prior art arrarigement which has been used commercially in automobiles fox connecting the engine with a transmission is shown in Figure 1.
In this Figure, ntuneral 10 indicat:e,ss the prior art flywheel which comprises a circular disc 11 of rotatably stiff but axially flexible relatively thin sheet metal. The disc 11 is of gerterally constant axial ttxiclmess although variable thaclozess discs can also be used. The disc 11 has a generally flat outer amulus 12 contacted with a slightly dished central portion 14 having a central $uide opening 15 surrounded by a plurality of smaller openings 16 for attac.lting the disc l t to a flanged end 18 of an engine crankshaft 19. The degree of dishing is optional and depends primarily upon the space available between the crankshaft 19 and an associated transmission input member such as a fluid coupling 20.
Beyond the outer annulus 12, the disc 11 has a short axial flange 21 to which is intermittently welded at 22 a steel ring gear 23 having outwardly facing teeth 24 adapted to be engaged by a starter drive gear (not shown) for starting the engine. Some prior art arrangements omit the flange 21 and weld the ring gear directly to the flat outer annulus 12 of the disc. Welding is usually intermittent, although US Patent No. 5,323,665 discloses a continuous weld bead to reduce starting induced vibrations.
During operation, stress concentrations at the root of the weld initiate cracks in the plate, as illustrated in Figure 2. Typically, the fatigue crack 25 follows around the base of the weld until the plate breaks free of the outer ring gear.
Catastrophic failure of the flexplate then occurs. To extend fatigue life, the usual approach involves adding an increasing number of spot welds, or a continuous weld bead as disclosed in US Patent No. 5,323,665, to retain the outer ring gear to the inner plate.
SUA'1MA1{Y Ur''1'ME 1NVttiN'.1'10.tV
The present invention provides a flexplate constrnzction with an improved weld structure between the imm.er plate and the outer ring gear which moves the stress concentration away fi;oxn the highly stressed outer perimeter of the plate and creatos a substantially longer path for a fatigue crack to propagate along before fatigue failure can occur. Tlae larger weld structure also stabilizes th.e floxplate against vibrations, allowing the inner plate and puter ring gear to act more like a single unit.
SRIEF DESCRIP'TION OF THE DRA'VINGS
Other advantages of the preaent itnvention will be readily appreciated as the same becames better uulderstood by reforence to the following detailed description when considered in connection with the accompanying 1 s drawings wherein:
Figure 1 is a cross-sectional view of a prior art flexplate flywheel;
Figure 2 is a parspective and a cross-sectional view of a prior art flexplate illustrating the locataon of conventional welds and the typical fatigue crack initiation origin;
Figure 3 is a perspective and a cross-sectional view according to the invention; and Figure 4 is a front or face view of three alteniate embodiments of the invention.
The present invention provides a flexplate constrnzction with an improved weld structure between the imm.er plate and the outer ring gear which moves the stress concentration away fi;oxn the highly stressed outer perimeter of the plate and creatos a substantially longer path for a fatigue crack to propagate along before fatigue failure can occur. Tlae larger weld structure also stabilizes th.e floxplate against vibrations, allowing the inner plate and puter ring gear to act more like a single unit.
SRIEF DESCRIP'TION OF THE DRA'VINGS
Other advantages of the preaent itnvention will be readily appreciated as the same becames better uulderstood by reforence to the following detailed description when considered in connection with the accompanying 1 s drawings wherein:
Figure 1 is a cross-sectional view of a prior art flexplate flywheel;
Figure 2 is a parspective and a cross-sectional view of a prior art flexplate illustrating the locataon of conventional welds and the typical fatigue crack initiation origin;
Figure 3 is a perspective and a cross-sectional view according to the invention; and Figure 4 is a front or face view of three alteniate embodiments of the invention.
DETAILED D1;SCkl.i.Pl.'IUN Ur' '1'Hll: Yltb;lb'1LliliED lLM13UUlM1L1V'1' Referring to the Figures, wherein like numerals indicate ldce or corresponding parts throughout the several views, Figure 3 shows an embodiment of modified llexplate flywheel 100 having an improved weld stnictuxe according to the invention. The flywheel gexi.ezally comprises a circular disc 110, which is a stamped metal plate with a flat outcr annulus 120 and a central guide opening simmunded by smaller opcninga 145 for attaching to the end of a crankshaft (aot shown in this figure).
io The outer annulus 120 of the disc 110 has a radial outer edge 150 to which is welded a steel ring gear 200 with teeth 210 for engagixAg a starter drive gear (not shown). The structure differs from the prior art in that the ring gear is welded to the inner circclar disc 110 via intermittent welds 160 that extend subataniially inside the interior of the disc 110. The prior art weld structures ar+e limited to the outer circumference of the circular disc 110 and do not extend into the disc interior.
The result of this change, wherein the ring gear is welded to the inner disc with intermittent welds extending into the disc interior, is to move the stress concentrations away from the disc perimeter and to create a substantially longer path for any fatigue crack to propagate along. The increased dimensions of the weld beads also provide a stiffening faature that minhmizes the hamful effects tur iILi aa .i I. uu rnn vuni,ttrao qW uua of vibrations induced by gear rotation during engine startijug. This stiffening feature is enhanced by pivvidin.g a weld bead of constant thickness, as illustrated in the rightmost s,ross-sectional view of Figum 3.
Figure 4 shows several other embodi.ments whereby a plurality of welds with different configurations A, B, C arc added to slxffen the disc portion.
Many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be anderstood that within the scope of the appended claims the invention may be practiced othaiwise than as specifioally dcscribcd.
io The outer annulus 120 of the disc 110 has a radial outer edge 150 to which is welded a steel ring gear 200 with teeth 210 for engagixAg a starter drive gear (not shown). The structure differs from the prior art in that the ring gear is welded to the inner circclar disc 110 via intermittent welds 160 that extend subataniially inside the interior of the disc 110. The prior art weld structures ar+e limited to the outer circumference of the circular disc 110 and do not extend into the disc interior.
The result of this change, wherein the ring gear is welded to the inner disc with intermittent welds extending into the disc interior, is to move the stress concentrations away from the disc perimeter and to create a substantially longer path for any fatigue crack to propagate along. The increased dimensions of the weld beads also provide a stiffening faature that minhmizes the hamful effects tur iILi aa .i I. uu rnn vuni,ttrao qW uua of vibrations induced by gear rotation during engine startijug. This stiffening feature is enhanced by pivvidin.g a weld bead of constant thickness, as illustrated in the rightmost s,ross-sectional view of Figum 3.
Figure 4 shows several other embodi.ments whereby a plurality of welds with different configurations A, B, C arc added to slxffen the disc portion.
Many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be anderstood that within the scope of the appended claims the invention may be practiced othaiwise than as specifioally dcscribcd.
Claims (3)
1. A flywheel for use on an automotive engine or the like, comprising:
= a substantially flat disc having an aperture in the center for mounting on a crankshaft of an engine;
= a ring portion, attached to the outer circumference of said disc by a suitable welding means, wherein = said welding means introduces at least one weld bead extending away from the outer circumference of said ring and towards the inner center of said disc.
= a substantially flat disc having an aperture in the center for mounting on a crankshaft of an engine;
= a ring portion, attached to the outer circumference of said disc by a suitable welding means, wherein = said welding means introduces at least one weld bead extending away from the outer circumference of said ring and towards the inner center of said disc.
2. The flywheel according to claim 1, wherein the at least one weld bead has a varying thickness that increases in thickness from the inner disc to the outer ring portion.
3. The flywheel according to claim 1, wherein the at least one weld bead has a constant thickness to provide local stiffening of the disc.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2285837 CA2285837C (en) | 1999-10-12 | 1999-10-12 | Improved two-piece flexplate design |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2285837 CA2285837C (en) | 1999-10-12 | 1999-10-12 | Improved two-piece flexplate design |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2285837A1 CA2285837A1 (en) | 2001-04-12 |
| CA2285837C true CA2285837C (en) | 2007-08-21 |
Family
ID=4164362
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2285837 Expired - Fee Related CA2285837C (en) | 1999-10-12 | 1999-10-12 | Improved two-piece flexplate design |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2285837C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9982748B2 (en) | 2012-12-12 | 2018-05-29 | Magna International | Flexplates and method for capacitor discharge welding of flexplates |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102588509B (en) * | 2012-02-23 | 2017-05-03 | 湖北六和天轮机械有限公司 | Flexible flywheel disc assembly |
-
1999
- 1999-10-12 CA CA 2285837 patent/CA2285837C/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9982748B2 (en) | 2012-12-12 | 2018-05-29 | Magna International | Flexplates and method for capacitor discharge welding of flexplates |
| US10975931B2 (en) | 2012-12-12 | 2021-04-13 | Magna International | Flexplates and method for capacitor discharge welding of flexplates |
Also Published As
| Publication number | Publication date |
|---|---|
| CA2285837A1 (en) | 2001-04-12 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |
Effective date: 20181012 |