CA2321492A1 - Engine balance apparatus - Google Patents
Engine balance apparatus Download PDFInfo
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- CA2321492A1 CA2321492A1 CA002321492A CA2321492A CA2321492A1 CA 2321492 A1 CA2321492 A1 CA 2321492A1 CA 002321492 A CA002321492 A CA 002321492A CA 2321492 A CA2321492 A CA 2321492A CA 2321492 A1 CA2321492 A1 CA 2321492A1
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- Canada
- Prior art keywords
- counterweights
- gear
- counterweight
- balancing apparatus
- void
- 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.)
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Classifications
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- 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
- F16F15/22—Compensation of inertia forces
- F16F15/26—Compensation of inertia forces of crankshaft systems using solid masses, other than the ordinary pistons, moving with the system, i.e. masses connected through a kinematic mechanism or gear system
- F16F15/264—Rotating balancer shafts
- F16F15/265—Arrangement of two or more balancer shafts
Abstract
An engine balancing apparatus has a housing assembly mounted to a vehicle engine. The housing assembly has spaced apart endwalls and two parallel extending support shafts connected to the endwalls. A first counterweight is rotatably mounted concentrically about a first of the support shafts. The first counterweight has a first gear, a lead filled first void and a phenolic filled second void diametrically opposed from said first void. A second counterweight is rotatably mounted concentrically about a second of said support shafts. The second counterweight has a second gear, a lead filled third void and a phenolic filled fourth void diametrically opposed from the third void. The second gear in is driven engagement with the first gear for counter rotation therewith. The first support shaft is positioned relative to the crankshaft of the engine for drivingly engaging the first gear. Each of the counterweights has a center of gravity offset from an axis of rotation whereby as the counterweights counter rotate an inertial force is generated which has a canceling effect on inertial forces generated by operation of the vehicle engine.
Description
Engine Balance Apparatus Field of Invention This invention relates to a balancing apparatus for a vehicle engine and more particularly to a twin counter-rotatingbalance shaft assembly for a four cylinder in-line internal combustion engine, which reduces engine vibration.
Background of the Invention Internal combustion engines of the reciprocating type have movable portions, which to become off balance during the operation of the engine. This causes vibration and noise. The vibration and noise are objectionableto the passengers of the vehicle and also cause degradation to engine parts, increasing component wear and fatigue.
Existing engine balance mechanisms seek to solve these problems, but are typically heavy, large, and produce considerable drag on the engine. Typical balance mechanisms use large, complicated cast housings to exclude oil from some areas and allow the oil to flow freely to other areas. The size and complexity of existing balance shaft mechanisms also increase their cost.
In addition, existing engine balancing mechanisms tend to be noisy due to the meshing of steel gears.
A conventional balancing device of this type typically includes a pair of cast or forged steel balance shafts which incorporate un-machined, as-cast eccentric weights as well as machined journal bearing surfaces or roller bearing surface seats. The bearings are held in split housings, typically line-bored after pre-assembly. Since the balance shafts typically turn at over 12,000 rpm (twice the engine speed), tolerances of the machined surfaces must be closely held. Thus, these devices require costly machining steps to achieve accuracy. Further, during operation of the engine, the eccentric weights cause shaft deflection resulting in misalignment between the shafts and bearing housings. This misalignment is greatest when the engine speed and bearing loads are highest, which has necessitated the use of costly, extra-precision bearings or pressure-fed lubrication of journals with engine oil.
Other products which attempt to solve the balance problems, include the 'balancer apparatus for engine' as described in United States Patent No. 5,305,656. This unit succeeds in providing a balancing of the secondary vibration in a four cylinder engine.
However, several disadvantages of this type of unit still exist. The length and size of such engine balance mechanisms require significant modifications to engines, oil pans and nearby vehicle sub-frames to allow packaging of the mechanism into the engine. The noise from this and other engine balance mechanisms are a source of passenger annoyance and may even be comparable to the engine vibration noise, which existed prior to the installation of the engine balance mechanism.
Significant inefficiency of engine balance mechanisms still exists resulting from parasitic losses 1o in the gears and particularly, the counterweights. Both the gears and counterweights may be partially or fully submerged in engine oil during their operation and considerable form drag exists from the counterweights of current engine balancing mechanisms. The cast housings in current engine balance mechanisms are large and heavy.
~ 5 Other conventional balance shaft pairs typically incorporate sprockets and chains or steel gears to drive one of the balance shafts via an engine crank shaft drive gear.
The first balance shaft drives the second balance shaft by the steel gears to produce counter-rotating motion.
During operation, gear noise and rattles occur which are caused by gear meshing and torsional crank shaft vibrations. Counter-measuresto avoid these problems have been proposed including 2o the use of anti-backlash gears and powder metal steel gears (with improved internal damping), but have been only partially successful. Non-metallic gears have also been tried unsuccessfully, due to high cyclic stresses caused by the torsional vibration of the crank shaft, transmitted through the gears, resisted by the high inertia of the rotating balance shaft components.
25 Summary of the Invention The disadvantages of the prior art may be overcome by providing a light weight, compact, low drag, low cost, relatively quiet engine balance mechanism.
3o It is desirable to provide a balancing apparatus for suppressing vibrations generated by unbalanced inertial forces of the components of the engine.
According to one aspect of the invention, there is provided driven gears, which are in plane with the counterweights. The apparatus makes use of the space within the body of the gears, and makes the material within the plane of the gears contribute to the counterbalancing effect of the counterweights. This dual use of the gear space provides for a shorter engine balance apparatus.
s This allows for flexibility in packaging the engine balancing apparatus into a multitude of engine configurations.
According to another aspect of the invention, the counterweights, which are typically longer in the axial direction than the gears, support the gears anywhere along the length of the 1 o counterweights. This allows flexibility in packaging the position of the driven gears relative to the end brackets and the engine bull gear in the engine balance apparatus.
According to another aspect of the invention, the counterweight consists of an axisymmetrically shaped portion, typically of steel, which contains an open pocket, or pockets, 15 for a low-density filler material. This allows the counterweight to remain round, reducing form drag and also ensures that its centroid is offset from the center axis, thus providing the mass offset which is desirable in a counterweight. Also provided for, is the addition of a second pocket, or pockets, in the counterweight, which may contain a material or materials of higher density, such as lead. This enhances the ability to increase the counterweight mass offset in a given package 2o space, keeping the size of the counterweights, and thus, the apparatus to a minimum.
According to another aspect of the invention, a counterweight, which may be separate from the driven gears of the apparatus; is axisymmetric. It consists of two or more portions, the first of which has an unsymmetrical form. The second is a covering material of a different 25 density, which effectively makes a fairing over the more conventional shape and makes the counterweightassembly axisymmetric, the simplest form of which would be cylindrical. Other materials of varying densities could be included to tune or optimize the mass offset.
According to another aspect of the invention, small, light weight, end brackets support the 3o engine balance center shafts, which supportthe counterweightsand gears.
These shafts are bolted to the end brackets to provide structural coupling between the two end brackets. The end brackets are considerably smaller than most balance shaft brackets or housings for an engine balancing apparatus of similar size.
According to another aspect of the invention, a thin, light weight metal or plastic cover is provided between the two end brackets for the purpose of controlling the amount of oil that is in contact with the gears and counterweights in the balance shaft apparatus. This cover may be held in place by conventional screws or other fasteners and may include a bonding or sealing agent at the interface to the end brackets to help prevent engine oil leaking into the enclosed area. The end brackets and cover form an enclosure from below and from the sides of the apparatus, while leaving the top area above the gears arid counterweight open. Typically, an engine balance apparatus of this nature is fixed to the engine, below the crank shaft, in the oil pan area. The apparatus would be significantly submerged if no covering were used to exclude the oil from this area. A small hole, or holes are included in the cover to allow small amounts of oil to enter the gear and counterweightarea to lubricate the gears. This oil is typically ejected from this area by flinging off of the gears to outside of the covered area at approximately the same rate that it is entering the balance shaft area through the hole or holes in the cover. The size and number of holes in the cover allows for tuning the rate at which oil enters the enclosed area during engine operation.
2o According to another aspect of the invention, cost can be reduced by using common parts in different areas of the apparatus. Typically, shafts and bearings are used in more than one location in an engine balancing apparatus. This invention also provides for the two end brackets to be common parts; the two counterweights can also be common parts. In the co-planar gear and counterweight embodiment discussed, a metallic gear would be pressed onto one of the counterweights and a plastic or composite gear would be insert molded onto the other counterweight.
According to another aspect of the invention, there is provided an engine balancing apparatus which has a housing assembly mounted to a vehicle engine. The housing assembly has 3o spaced apart endwalls and two parallel extending support shafts connected to the endwalls. A first counterweight is rotatably mounted concentrically about a first of the support shafts. The first _4_ counterweight has a first gear, a lead filled first void and a phenolic filled second void diametrically opposed from said first void. A second counterweight is rotatably mounted concentrically about a second of said support shafts. The second counterweighthas a second gear, a lead filled third void and a phenolic filled fourth void diametrically opposed from the third void.
The second gear is in driven engagement with the first gear for counter rotation therewith. The first support shaft is positioned relative to the crankshaft of the engine for drivingly engaging the first gear. Each of the counterweights has a center of gravity offset from an axis of rotation whereby as the counterweightscounterrotate an inertial force is generated which has a cancelling effect on inertial forces generated by operation of the vehicle engine.
to Description of the Drawings The invention may best be understood with reference to the accompanying drawings wherein an illustrative embodiment is shown.
Figure 1 is an isometric view of a balancing apparatus provided in accordance with the principles of the present invention;
Figure 2 is a front elevational view, partially broken away, of the apparatus of Figure 1;
Figure 3 is a sectional view of the apparatus of Figure 2, along the lines A-A;
Figure 4 is a sectional view of the apparatus of Figure 2, along the lines B-B;
2o Figure 5 is an end elevational view of the counterweights of the apparatus of Figure 1;
Figure 6 is a top plan view of a second embodiment'of the balancing apparatus of the present invention;
Figure 7 is a section view of a counterweight of the balancing apparatus of Figure 6, along the lines C-C.
Description of the Invention Referring to the drawings, there is shown an engine balancing apparatus 10, which embodies the principles of the present invention. The engine balancing apparatus 10 is 3o constructed and arranged to suppress secondary vibrations in a conventional four cylinder, in line, internal combustion engine as disclosed, for example, in U.S. Patent No.
5,305,656. The _5_ conventional engine includes a rotatable crank shaft and a plurality of pistons and cylinders for causing rotation of the crank shaft. As is typical, the crank shaft includes a helical drive gear.
mounted for rotation therewith, referred to as the bull gear within this document, of the type disclosed in U.S. Patent No. 5,305,656.
The balancing apparatus 10 comprises a forward end bracket 12 and the rear end bracket 14. Typically the balancing apparatus 10 is bolted directly to the engine block 16 via four mounting bolts 18 which extend through mounting bores in the ends of brackets 12, 14. The end brackets 12,14 support the inner shafts 20. Each end 22 of shaft 20 has a smaller diameter than 1 o a middle portion. The ends 22 extend through bores 24 of brackets 12 and 14. The adj acent bores 24 are offset relative to the upper mounting surface of the brackets 12 and 14. The smaller diameter ends 22 present shoulders for positioning the brackets 12 and 14 in a spaced parallel relation. Bolts 23, via washers 25, engage threaded bores in the ends 22 to retain the shafts 20 in place.
The middle portion of shafts 20 each support a counterweight26 and 28. Needle bearings 30 are mounted between the shafts 20 and the counterweight weights 26 and 28 allowing for rotation of the counterweights 26 and 28 relative to the inner shafts 20. End play of the counterweight26 and 28 is controlled by thrust bearings 32 which retain the axial position of the 2o counterweight 26, 28 between the end brackets I2, 14.
Counterweight26 has a steel gear 34 which is pressed thereon and counterweight 28 has a phenolic gear 36, which is molded thereon. Note that a toothed form is provided on the counterweights 26, 28 to enhance the attachment of the steel gear 34 and phenolic gear 36.
During assembly of the balancing apparatus 10, the counterweights 26, 28 must be arranged such that the centers of gravity are opposite each other, when the two gears 34, 36 are brought into operative engagement. This ensures that the counterweights 26, 28 work together to sum the inertial forces in the vertical direction and to cancel the horizontal inertial forces as they rotate in opposing directions.
WO 99141742 PCTICA99/o0071 Each counterweight 26, 28 has preferably two diametrically opposed voids 42, 44, which are filled with materials of differing densities. On one side of each counterweight 26, 28, a relatively dense material 46, preferably lead, is inserted into void 42. On the other side, a relatively less dense material 48, preferably a polymer, such as phenolic resin, is used to fill the second void 44. By using the polymer insert 48, the lead insert 46, and the steel body of the counterweights26, 28, which itselfhas an offset center of gravity, a large center of gravity offset from the axis of rotation can be achieved in the counterweight.
A thin sheet cover 50 of metal, plastic or other suitable material is held into place by 1o conventional screws 52. Tt is desirable to exclude the engine oil, which typically resides in the oil pan and typically surrounds the engine balance apparatus, from engulfing the gear and counterweight portion of the apparatus 10. Excess engine oil causes excessive viscous drag on the gears 34, 36 and counterweight 26, 28 portions of the balancing apparatus 10. The cover 50 and end brackets 12, 14 form a semi-enclosed area which encloses the gears 34, 36 and the counterweights 26, 28 on the sides and below. At least one small hole 54 in the lower portion of the cover 50 regulates the flow of lubricating oil into the enclosed area. Oil splash caused by the gear teeth hitting the enclosed pool of oil, ejects oil from the top of the enclosed area, preventing the oil level from raising higher than is necessary to lubricate the gears 34, 36. The enclosure thus provides an area relatively free from the oil in the oil pan reservoir and reduces parasitic losses 2o that would result from the gears and counterweights rotating in a viscous oil environment.
Operation of the invention The bull gear 40 is affixed to the engine crank shaft and rotates at crank shaft speed. The bull gear 40 engages only the phenolic gear 36 because the gear 34 is offset relative to the phenolic gear 36. The phenolic gear 36 is sized relative to the bull gear~40, such that it typically runs at twice the speed of the bull gear 40. The damping characteristics of phenolic reduce the noise produced by the engagement of the two gears 36 and 40. Counterweight 28 rotates at the same speed as the phenolic gear 36. The phenolic gear 36 also engages the steel gear 34 which is caused to rotate at an equal speed, but opposite in direction to the phenolic gear 36. The 3o damping characteristics of phenolic again reduces the noise generated by the two gears 34 and 36 running together. The engagement of the phenolic gear 36 to the steel gear 34 causes the steel _7_ gear 34 and its counterweight 26 to rotate in an opposite sense to the phenolic gear 36 and its counterweight28. The opposite rotation of the two counterweights 26, 28 enables them to work together to sum the respective inertial forces in the vertical direction and to cancel the horizontal inertial forces as the centers of gravity remain in opposing orientation in the horizontal direction.
The resultant inertial forces generated by the two counterweights 26, 28 cancels the secondary inertial forces generated by the engine pistons and connecting rods. The mass offset in the counterweights 26, 28 is provided by the use of differing density materials in the counterweights 26, 28.
to Referring to Figures 6 and 7, an alternate embodiment is illustrated. In this embodiment, the counterweights 126,128 are not integral with the gears 134, I36, respectively, but are attached via a hollow shaft 124. The axisymmetric shaped counterweights 126, 128 consist of a plurality of materials of varying densities. For example, a steel core 142 is combined with a polymer fairing 148. The counterweights may be constructed by first machining the steel core 142 and I S then molding the polymer fairing 148 onto the steel core 142.
It thus will be seen that the objects of this invention have been fully and effectively accomplished. It will be realized, however, that the foregoing preferred embodiment of the present invention has been shown and described for the purposes of illustrating the structural and 2o functional principles of the present invention and is subject to change without departure from such principles.
_g_
Background of the Invention Internal combustion engines of the reciprocating type have movable portions, which to become off balance during the operation of the engine. This causes vibration and noise. The vibration and noise are objectionableto the passengers of the vehicle and also cause degradation to engine parts, increasing component wear and fatigue.
Existing engine balance mechanisms seek to solve these problems, but are typically heavy, large, and produce considerable drag on the engine. Typical balance mechanisms use large, complicated cast housings to exclude oil from some areas and allow the oil to flow freely to other areas. The size and complexity of existing balance shaft mechanisms also increase their cost.
In addition, existing engine balancing mechanisms tend to be noisy due to the meshing of steel gears.
A conventional balancing device of this type typically includes a pair of cast or forged steel balance shafts which incorporate un-machined, as-cast eccentric weights as well as machined journal bearing surfaces or roller bearing surface seats. The bearings are held in split housings, typically line-bored after pre-assembly. Since the balance shafts typically turn at over 12,000 rpm (twice the engine speed), tolerances of the machined surfaces must be closely held. Thus, these devices require costly machining steps to achieve accuracy. Further, during operation of the engine, the eccentric weights cause shaft deflection resulting in misalignment between the shafts and bearing housings. This misalignment is greatest when the engine speed and bearing loads are highest, which has necessitated the use of costly, extra-precision bearings or pressure-fed lubrication of journals with engine oil.
Other products which attempt to solve the balance problems, include the 'balancer apparatus for engine' as described in United States Patent No. 5,305,656. This unit succeeds in providing a balancing of the secondary vibration in a four cylinder engine.
However, several disadvantages of this type of unit still exist. The length and size of such engine balance mechanisms require significant modifications to engines, oil pans and nearby vehicle sub-frames to allow packaging of the mechanism into the engine. The noise from this and other engine balance mechanisms are a source of passenger annoyance and may even be comparable to the engine vibration noise, which existed prior to the installation of the engine balance mechanism.
Significant inefficiency of engine balance mechanisms still exists resulting from parasitic losses 1o in the gears and particularly, the counterweights. Both the gears and counterweights may be partially or fully submerged in engine oil during their operation and considerable form drag exists from the counterweights of current engine balancing mechanisms. The cast housings in current engine balance mechanisms are large and heavy.
~ 5 Other conventional balance shaft pairs typically incorporate sprockets and chains or steel gears to drive one of the balance shafts via an engine crank shaft drive gear.
The first balance shaft drives the second balance shaft by the steel gears to produce counter-rotating motion.
During operation, gear noise and rattles occur which are caused by gear meshing and torsional crank shaft vibrations. Counter-measuresto avoid these problems have been proposed including 2o the use of anti-backlash gears and powder metal steel gears (with improved internal damping), but have been only partially successful. Non-metallic gears have also been tried unsuccessfully, due to high cyclic stresses caused by the torsional vibration of the crank shaft, transmitted through the gears, resisted by the high inertia of the rotating balance shaft components.
25 Summary of the Invention The disadvantages of the prior art may be overcome by providing a light weight, compact, low drag, low cost, relatively quiet engine balance mechanism.
3o It is desirable to provide a balancing apparatus for suppressing vibrations generated by unbalanced inertial forces of the components of the engine.
According to one aspect of the invention, there is provided driven gears, which are in plane with the counterweights. The apparatus makes use of the space within the body of the gears, and makes the material within the plane of the gears contribute to the counterbalancing effect of the counterweights. This dual use of the gear space provides for a shorter engine balance apparatus.
s This allows for flexibility in packaging the engine balancing apparatus into a multitude of engine configurations.
According to another aspect of the invention, the counterweights, which are typically longer in the axial direction than the gears, support the gears anywhere along the length of the 1 o counterweights. This allows flexibility in packaging the position of the driven gears relative to the end brackets and the engine bull gear in the engine balance apparatus.
According to another aspect of the invention, the counterweight consists of an axisymmetrically shaped portion, typically of steel, which contains an open pocket, or pockets, 15 for a low-density filler material. This allows the counterweight to remain round, reducing form drag and also ensures that its centroid is offset from the center axis, thus providing the mass offset which is desirable in a counterweight. Also provided for, is the addition of a second pocket, or pockets, in the counterweight, which may contain a material or materials of higher density, such as lead. This enhances the ability to increase the counterweight mass offset in a given package 2o space, keeping the size of the counterweights, and thus, the apparatus to a minimum.
According to another aspect of the invention, a counterweight, which may be separate from the driven gears of the apparatus; is axisymmetric. It consists of two or more portions, the first of which has an unsymmetrical form. The second is a covering material of a different 25 density, which effectively makes a fairing over the more conventional shape and makes the counterweightassembly axisymmetric, the simplest form of which would be cylindrical. Other materials of varying densities could be included to tune or optimize the mass offset.
According to another aspect of the invention, small, light weight, end brackets support the 3o engine balance center shafts, which supportthe counterweightsand gears.
These shafts are bolted to the end brackets to provide structural coupling between the two end brackets. The end brackets are considerably smaller than most balance shaft brackets or housings for an engine balancing apparatus of similar size.
According to another aspect of the invention, a thin, light weight metal or plastic cover is provided between the two end brackets for the purpose of controlling the amount of oil that is in contact with the gears and counterweights in the balance shaft apparatus. This cover may be held in place by conventional screws or other fasteners and may include a bonding or sealing agent at the interface to the end brackets to help prevent engine oil leaking into the enclosed area. The end brackets and cover form an enclosure from below and from the sides of the apparatus, while leaving the top area above the gears arid counterweight open. Typically, an engine balance apparatus of this nature is fixed to the engine, below the crank shaft, in the oil pan area. The apparatus would be significantly submerged if no covering were used to exclude the oil from this area. A small hole, or holes are included in the cover to allow small amounts of oil to enter the gear and counterweightarea to lubricate the gears. This oil is typically ejected from this area by flinging off of the gears to outside of the covered area at approximately the same rate that it is entering the balance shaft area through the hole or holes in the cover. The size and number of holes in the cover allows for tuning the rate at which oil enters the enclosed area during engine operation.
2o According to another aspect of the invention, cost can be reduced by using common parts in different areas of the apparatus. Typically, shafts and bearings are used in more than one location in an engine balancing apparatus. This invention also provides for the two end brackets to be common parts; the two counterweights can also be common parts. In the co-planar gear and counterweight embodiment discussed, a metallic gear would be pressed onto one of the counterweights and a plastic or composite gear would be insert molded onto the other counterweight.
According to another aspect of the invention, there is provided an engine balancing apparatus which has a housing assembly mounted to a vehicle engine. The housing assembly has 3o spaced apart endwalls and two parallel extending support shafts connected to the endwalls. A first counterweight is rotatably mounted concentrically about a first of the support shafts. The first _4_ counterweight has a first gear, a lead filled first void and a phenolic filled second void diametrically opposed from said first void. A second counterweight is rotatably mounted concentrically about a second of said support shafts. The second counterweighthas a second gear, a lead filled third void and a phenolic filled fourth void diametrically opposed from the third void.
The second gear is in driven engagement with the first gear for counter rotation therewith. The first support shaft is positioned relative to the crankshaft of the engine for drivingly engaging the first gear. Each of the counterweights has a center of gravity offset from an axis of rotation whereby as the counterweightscounterrotate an inertial force is generated which has a cancelling effect on inertial forces generated by operation of the vehicle engine.
to Description of the Drawings The invention may best be understood with reference to the accompanying drawings wherein an illustrative embodiment is shown.
Figure 1 is an isometric view of a balancing apparatus provided in accordance with the principles of the present invention;
Figure 2 is a front elevational view, partially broken away, of the apparatus of Figure 1;
Figure 3 is a sectional view of the apparatus of Figure 2, along the lines A-A;
Figure 4 is a sectional view of the apparatus of Figure 2, along the lines B-B;
2o Figure 5 is an end elevational view of the counterweights of the apparatus of Figure 1;
Figure 6 is a top plan view of a second embodiment'of the balancing apparatus of the present invention;
Figure 7 is a section view of a counterweight of the balancing apparatus of Figure 6, along the lines C-C.
Description of the Invention Referring to the drawings, there is shown an engine balancing apparatus 10, which embodies the principles of the present invention. The engine balancing apparatus 10 is 3o constructed and arranged to suppress secondary vibrations in a conventional four cylinder, in line, internal combustion engine as disclosed, for example, in U.S. Patent No.
5,305,656. The _5_ conventional engine includes a rotatable crank shaft and a plurality of pistons and cylinders for causing rotation of the crank shaft. As is typical, the crank shaft includes a helical drive gear.
mounted for rotation therewith, referred to as the bull gear within this document, of the type disclosed in U.S. Patent No. 5,305,656.
The balancing apparatus 10 comprises a forward end bracket 12 and the rear end bracket 14. Typically the balancing apparatus 10 is bolted directly to the engine block 16 via four mounting bolts 18 which extend through mounting bores in the ends of brackets 12, 14. The end brackets 12,14 support the inner shafts 20. Each end 22 of shaft 20 has a smaller diameter than 1 o a middle portion. The ends 22 extend through bores 24 of brackets 12 and 14. The adj acent bores 24 are offset relative to the upper mounting surface of the brackets 12 and 14. The smaller diameter ends 22 present shoulders for positioning the brackets 12 and 14 in a spaced parallel relation. Bolts 23, via washers 25, engage threaded bores in the ends 22 to retain the shafts 20 in place.
The middle portion of shafts 20 each support a counterweight26 and 28. Needle bearings 30 are mounted between the shafts 20 and the counterweight weights 26 and 28 allowing for rotation of the counterweights 26 and 28 relative to the inner shafts 20. End play of the counterweight26 and 28 is controlled by thrust bearings 32 which retain the axial position of the 2o counterweight 26, 28 between the end brackets I2, 14.
Counterweight26 has a steel gear 34 which is pressed thereon and counterweight 28 has a phenolic gear 36, which is molded thereon. Note that a toothed form is provided on the counterweights 26, 28 to enhance the attachment of the steel gear 34 and phenolic gear 36.
During assembly of the balancing apparatus 10, the counterweights 26, 28 must be arranged such that the centers of gravity are opposite each other, when the two gears 34, 36 are brought into operative engagement. This ensures that the counterweights 26, 28 work together to sum the inertial forces in the vertical direction and to cancel the horizontal inertial forces as they rotate in opposing directions.
WO 99141742 PCTICA99/o0071 Each counterweight 26, 28 has preferably two diametrically opposed voids 42, 44, which are filled with materials of differing densities. On one side of each counterweight 26, 28, a relatively dense material 46, preferably lead, is inserted into void 42. On the other side, a relatively less dense material 48, preferably a polymer, such as phenolic resin, is used to fill the second void 44. By using the polymer insert 48, the lead insert 46, and the steel body of the counterweights26, 28, which itselfhas an offset center of gravity, a large center of gravity offset from the axis of rotation can be achieved in the counterweight.
A thin sheet cover 50 of metal, plastic or other suitable material is held into place by 1o conventional screws 52. Tt is desirable to exclude the engine oil, which typically resides in the oil pan and typically surrounds the engine balance apparatus, from engulfing the gear and counterweight portion of the apparatus 10. Excess engine oil causes excessive viscous drag on the gears 34, 36 and counterweight 26, 28 portions of the balancing apparatus 10. The cover 50 and end brackets 12, 14 form a semi-enclosed area which encloses the gears 34, 36 and the counterweights 26, 28 on the sides and below. At least one small hole 54 in the lower portion of the cover 50 regulates the flow of lubricating oil into the enclosed area. Oil splash caused by the gear teeth hitting the enclosed pool of oil, ejects oil from the top of the enclosed area, preventing the oil level from raising higher than is necessary to lubricate the gears 34, 36. The enclosure thus provides an area relatively free from the oil in the oil pan reservoir and reduces parasitic losses 2o that would result from the gears and counterweights rotating in a viscous oil environment.
Operation of the invention The bull gear 40 is affixed to the engine crank shaft and rotates at crank shaft speed. The bull gear 40 engages only the phenolic gear 36 because the gear 34 is offset relative to the phenolic gear 36. The phenolic gear 36 is sized relative to the bull gear~40, such that it typically runs at twice the speed of the bull gear 40. The damping characteristics of phenolic reduce the noise produced by the engagement of the two gears 36 and 40. Counterweight 28 rotates at the same speed as the phenolic gear 36. The phenolic gear 36 also engages the steel gear 34 which is caused to rotate at an equal speed, but opposite in direction to the phenolic gear 36. The 3o damping characteristics of phenolic again reduces the noise generated by the two gears 34 and 36 running together. The engagement of the phenolic gear 36 to the steel gear 34 causes the steel _7_ gear 34 and its counterweight 26 to rotate in an opposite sense to the phenolic gear 36 and its counterweight28. The opposite rotation of the two counterweights 26, 28 enables them to work together to sum the respective inertial forces in the vertical direction and to cancel the horizontal inertial forces as the centers of gravity remain in opposing orientation in the horizontal direction.
The resultant inertial forces generated by the two counterweights 26, 28 cancels the secondary inertial forces generated by the engine pistons and connecting rods. The mass offset in the counterweights 26, 28 is provided by the use of differing density materials in the counterweights 26, 28.
to Referring to Figures 6 and 7, an alternate embodiment is illustrated. In this embodiment, the counterweights 126,128 are not integral with the gears 134, I36, respectively, but are attached via a hollow shaft 124. The axisymmetric shaped counterweights 126, 128 consist of a plurality of materials of varying densities. For example, a steel core 142 is combined with a polymer fairing 148. The counterweights may be constructed by first machining the steel core 142 and I S then molding the polymer fairing 148 onto the steel core 142.
It thus will be seen that the objects of this invention have been fully and effectively accomplished. It will be realized, however, that the foregoing preferred embodiment of the present invention has been shown and described for the purposes of illustrating the structural and 2o functional principles of the present invention and is subject to change without departure from such principles.
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Claims (10)
1. A balancing apparatus (14) for a vehicle engine having a driving crankshaft, comprising:
a housing assembly constructed and arranged to be mounted to said vehicle engine and comprising spaced apart endwalls (12, 14) and two parallel attending support shafts (20) connected to said endwalls, a first counterweight (26, 126) having a first gear (34, 134), said first counterweight rotatably mounted concentrically about a first of said support shafts.
a second counterweight (28, 128) having a second gear (36, 136), said second counterweight rotatably mounted concentrically about a second of said support shafts, said second gear in driven engagement with the first gear for counter rotation therewith, said first of said support shafts pond relative to said crankshaft for drivingly engaging the first gear with the crankshaft, each of said counterweights (26, 126, 28, 128) has a center of gravity offset from an axis of rotation whereby as said counterweights (26, 126, 28, 128) counter rotate an inertial force is generated which has a canceling effect on inertial forces generated by operation of the vehicle engine, characterized by said first and second counterweights (26, 126, 28, 128) each having an axisymmetric shape.
a housing assembly constructed and arranged to be mounted to said vehicle engine and comprising spaced apart endwalls (12, 14) and two parallel attending support shafts (20) connected to said endwalls, a first counterweight (26, 126) having a first gear (34, 134), said first counterweight rotatably mounted concentrically about a first of said support shafts.
a second counterweight (28, 128) having a second gear (36, 136), said second counterweight rotatably mounted concentrically about a second of said support shafts, said second gear in driven engagement with the first gear for counter rotation therewith, said first of said support shafts pond relative to said crankshaft for drivingly engaging the first gear with the crankshaft, each of said counterweights (26, 126, 28, 128) has a center of gravity offset from an axis of rotation whereby as said counterweights (26, 126, 28, 128) counter rotate an inertial force is generated which has a canceling effect on inertial forces generated by operation of the vehicle engine, characterized by said first and second counterweights (26, 126, 28, 128) each having an axisymmetric shape.
2. A balancing apparatus as claimed in claim 1 wherein each of said counterweights has a first void (42) having a fast material (46) having a density greater than or less than a material comprising the counterweights.
3. A balancing apparatus as claimed in claim 2 wherein each of said counterweights has a second void (44) diametrically opposed from said first void, said second void (44) having a second material (48) having a density less than the material comprising the counterweights if said first material has a density greater than said first material or having a density greater than the material comprising the counterweights if said first material has a density less than said first material.
4. A balancing apparatus as claimed in claim 3 wherein said first material (46) is lead and said second material (48) is phenolic resin.
5. A balancing apparatus as in claims 2, 3 or 4 wherein at least one of said first and second gears (34, 134, 36, 136) comprises a material selected from a group comprising high damping ferrous material, powder metal, plastic and non-ferrous material.
6. A balancing apparatus as claimed in claims 2, 3 or 4 wherein at least one of said first and second gears (34, 134, 36, 136) is phenolic.
7. A balancing apparatus as claimed in claims 2, 3 or 4 wherein said first and second gears (34, 134, 36, 136) are phenolic.
8. A balancing apparatus as claimed in claims 3, 6 or 7 wherein a set of needle bearings (30) rotatably supports each of said counterweights,
9. A balancing apparatus as claimed is claims 5, 6 or 7 wherein each of said counterweight is mounted between thrust washers (32) which frictionally engage mid endwalls.
10. A balancing apparatus as claimed is claims 8 or 9 wherein said housing assembly further comprises a cover (50) extending between said endwalls.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US7642598P | 1998-02-18 | 1998-02-18 | |
| US60/076,425 | 1998-02-18 | ||
| PCT/CA1999/000071 WO1999042742A2 (en) | 1998-02-18 | 1999-02-04 | Engine balance apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2321492A1 true CA2321492A1 (en) | 1999-08-26 |
Family
ID=22131926
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002321492A Abandoned CA2321492A1 (en) | 1998-02-18 | 1999-02-04 | Engine balance apparatus |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA2321492A1 (en) |
| WO (1) | WO1999042742A2 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB9912536D0 (en) * | 1999-05-29 | 1999-07-28 | Simpson International Uk Limit | A balance shaft assembly |
| FR2823279B1 (en) * | 2001-04-09 | 2005-11-11 | Renault Sas | BALANCING SHAFT COMPRISING CYLINDRICAL BALANCING BLOCKS PRODUCED BY OVERMOLDING |
| ES2699476T3 (en) * | 2010-02-09 | 2019-02-11 | Fpt Ind Spa | Mass system of counter-rotation to balance the vibrations produced by the engine of a vehicle |
| FR3038025A1 (en) * | 2015-06-29 | 2016-12-30 | Skf Ab | BALANCING SHAFT MODULE OF A COMBUSTION ENGINE AND COMBUSTION ENGINE |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3667317A (en) * | 1970-08-26 | 1972-06-06 | Int Harvester Co | Balancer |
| GB2186914B (en) * | 1986-02-22 | 1989-11-15 | Triumph Motorcycles Coventry | Balancer for internal combustion engine |
| FR2720464B1 (en) * | 1994-05-31 | 1996-08-30 | Peugeot | Device for adjusting the center distance of a toothed wheel and a meshing pinion carried respectively by the crankshaft of an internal combustion engine and one of two balancing shafts of this engine. |
| JP3554429B2 (en) * | 1996-02-06 | 2004-08-18 | 本田技研工業株式会社 | Rotary shaft lubrication structure |
| US5743230A (en) * | 1996-02-06 | 1998-04-28 | Honda Giken Kogyo Kabushiki Kaisha | Balancer shaft supporting structure in engine |
-
1999
- 1999-02-04 WO PCT/CA1999/000071 patent/WO1999042742A2/en active Application Filing
- 1999-02-04 CA CA002321492A patent/CA2321492A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| WO1999042742A2 (en) | 1999-08-26 |
| WO1999042742A3 (en) | 1999-10-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |