Counterweight balancing gear with pellet damper

Abstract

The present disclosure relates to a counterweighted balance gear with a pellet damper. An engine system has a crankshaft gear coupled to an engine crankshaft and a balance gear coupled to a balance shaft. The balance gear is formed by a wheel disc having opposing first and second sides and a series of gear teeth. A first sector of the wheel disc has at least one hole passing through it, and an opposing second sector of the wheel disc defines a recess that intersects the first side. The balance gear has a damper formed by a cover plate connected to the first side, the cover plate being connected to the first side to enclose the recess and contain a plurality of pellets therein. A gear and a method of forming a gear are also provided, the gear having a first sector and a second sector, the first sector defining at least one hole passing through it, and the second sector defining a recess that intersects the first side. A plurality of pellets are disposed in the recess, and the cover plate encloses the recess to form a damper.

Description

Technical Field

[0001] Various embodiments are directed to a counterweight balancing gear, such as a counterweight balancing gear for use on a counterweight balancing shaft of an engine. Background Art

[0002] Gear transmission systems often produce tonal noise and vibration at harmonics of the gear meshing frequency, and this can be caused by the change in contact force between the driving gear and the driven gear as the gears rotate. The interaction between the gears can lead to a noise commonly referred to as gear whine. Gear whine is mainly caused by the transmission error between the meshing teeth of the two gears, and can depend on several factors including torsional load, gear design, gear tooth profile, total number of teeth, number of contacting teeth, gear mass and inertia. Gear whine can increase in the case of high torsional excitation, and can be further aggravated at various orders or at various harmonics based on system dynamics. Summary of the invention

[0003] In an embodiment, an engine system has a crankshaft gear coupled to a crankshaft of the engine for rotation therewith. The engine system has a balance gear coupled to a balance shaft for rotation therewith, wherein the balance gear and the crankshaft gear mesh. The balance gear is formed by a wheel disc having opposing first and second sides extending radially outward to a peripheral edge, the peripheral edge defining a series of gear teeth. A first sector of the wheel disc has at least one hole passing therethrough, and an opposing second sector of the wheel disc defines a recess intersecting the first side. The balance gear has a damper formed by a cover plate coupled to a first side of the wheel disc, the cover plate coupled to the first side of the wheel disc to enclose the recess and contain a plurality of particles therein.

[0004] According to one embodiment of the present invention, the cover plate and the recess cooperate to define a volume of the damper; wherein the plurality of particles fill between 80% and 90% of the volume.

[0005] In another embodiment, a gear for a vehicle axle has a wheel disc having opposing first and second sides extending radially outward to an edge defining a series of gear teeth. The wheel disc has a first sector defining at least one hole through the first sector and a second sector defining a recess intersecting the first side and a plurality of particles disposed in the recess. A cover plate is connected to the first side of the wheel disc to close the recess.

[0006] According to one embodiment of the invention, the first sector provides a first half of the wheel disc and the second sector provides a second half of the wheel disc.

[0007] According to one embodiment of the invention, the recess and the cover plate cooperate to define a volume therebetween.

[0008] According to an embodiment of the present invention, the certain volume ranges from 10% to 40% of the volume of the second sector.

[0009] According to an embodiment of the invention, said plurality of particles is provided to fill up to 90% of said certain volume.

[0010] In yet another embodiment, a method of forming a balance gear for a vehicle balance shaft is provided. A wheel disc is formed having opposing first and second sides extending radially outward to a circumferential edge. A series of gear teeth are formed on the circumferential edge. A single recess is formed into the wheel disc, the recess intersecting the first side of the wheel disc and extending to an impermeable depth in the wheel disc, the recess extending adjacent to the circumferential edge. At least one hole is formed in the wheel disc, wherein the at least one hole intersects the first and second sides of the wheel disc and is radially opposite to the recess. A plurality of pellets are disposed in the recess to achieve a specified fill rate. A cover plate is attached to the first side of the wheel disc to close the recess, retain the plurality of pellets in the recess, and form an internal damper in the balance gear. The volume of the internal damper, the specified fill rate, and the diameter of the pellets are designed to damp the whine caused by at least second-order deformation of the balance gear.

[0011] According to an embodiment of the present invention, the method further comprises providing a sealing member between the cover plate and the wheel disc to seal the recess. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 shows a schematic diagram of an internal combustion engine configured to implement various embodiments according to the present disclosure;

[0013] Figure 2 Shown for Figure 1 A perspective view of a crankshaft and balance shaft assembly of an engine;

[0014] Figure 3 shows an exploded view of a balance gear and a balance shaft according to an embodiment;

[0015] Figure 4 Shows Figure 3 A plan view of the balance gear with the cover removed;

[0016] Figure 5 Shows Figure 4 A cross-sectional view of a balance gear;

[0017] Figure 6 According to an optional embodiment, Figure 3 A balance gear used with a balance shaft;

[0018] Figure 7 According to another alternative embodiment, Figure 3A balance gear used with a balance shaft;

[0019] Figure 8 Yes Figure 3 A graph of acoustic mass versus frequency comparing a balancing gear of the invention with a conventional counterweight balancing gear and a balancing gear with a tuned mass damper;

[0020] Fig. 9 A method of forming a weighted balancing gear with a damper according to an embodiment is shown. DETAILED DESCRIPTION

[0021] As needed, specific embodiments of the present disclosure are provided herein; however, it should be understood that the disclosed embodiments are merely examples and may be implemented in various alternative forms. The drawings are not necessarily drawn to scale; some features may be exaggerated or minimized to illustrate details of particular components. Therefore, the specific structural and functional details disclosed herein should not be interpreted as limiting, but merely as a representative basis for teaching those skilled in the art to apply the present disclosure in various forms.

[0022] Vehicles typically use intermeshing gears to transfer torque and power in the vehicle and operate various vehicle systems and components. The vehicle is provided with an internal combustion engine and a transmission system, each of which may include intermeshing gears. Various intermeshing gears or gear trains may generate tonal noise and vibration at harmonics of the gear meshing frequency. The gear teeth of the driving gear mesh with the gear teeth of the driven gear and contact to rotate the driven gear, and gear whine is the product of the change in the contact force between the driving gear and the driven gear when the gear rotates. Gear whine may be caused or increased by errors or variability in the transmission of force from the gear teeth of the driving gear to the gear teeth of the driven gear. For gears that produce a certain degree of deflection during use, gear whine may be further amplified. Gear whine may be a function of operating parameters and conditions (including torsional load, gear design, gear tooth profile, number of gear teeth, gear mass and inertia) between various gears.

[0023] Figure 1 A schematic diagram of an internal combustion engine system 20 configured to implement various embodiments according to the present disclosure is shown. In some embodiments, the engine 20 can be used as the sole prime mover in a vehicle, such as a conventional vehicle or a stop / start vehicle. In other embodiments, the engine can be used in a hybrid vehicle, where an additional prime mover, such as an electric motor, can be used to provide additional power to propel the vehicle.

[0024] The engine 20 has a cylinder block and a cylinder head that cooperate to define a plurality of cylinders 22, of which one cylinder is shown. The engine 20 may have one cylinder, two cylinders, three cylinders, four cylinders, or more than four cylinders. A piston 24 is disposed in each cylinder and is connected to a crankshaft 26 via a connecting rod 28.

[0025] One or more intake valves 30 control flow from an intake manifold 32 into the cylinder 22. One or more exhaust valves 34 control flow from the cylinder 22 to an exhaust manifold 36. The intake and exhaust valves 30, 34 may be operated in various ways known in the art to control engine operation. The engine 20 is shown with intake and exhaust valves 30, 34 having associated camshafts 38, 40, respectively, in a direct injection overhead cam configuration. The engine and valves 30, 34 may be configured in various ways known in the art, for example, as a single overhead camshaft, dual overhead camshafts, direct injection camshaft actuation, overhead valves with valves operated by push rods or rockers, etc. The camshafts 38, 40 may be rotatably connected to and driven by the crankshaft 26, and in one embodiment, are driven by a gear train according to the present disclosure described below.

[0026] Each cylinder 22 can be operated under a four-stroke cycle including an intake stroke, a compression stroke, an ignition stroke, and an exhaust stroke. In other embodiments, the engine can operate with a two-stroke cycle. The position of the piston 24 at the top of the cylinder 22 is generally referred to as the top dead center (TDC). The position of the piston 24 at the bottom of the cylinder is generally referred to as the bottom dead center (BDC).

[0027] During the intake stroke, the intake valve 30 opens and the exhaust valve 30 closes while the piston 24 moves from the top of the cylinder 22 to the bottom of the cylinder 22 to direct air from the intake manifold to the combustion chamber.

[0028] During the compression stroke, the intake valve 30 and the exhaust valve 34 are closed. The piston 24 moves from the bottom of the cylinder 22 toward the top of the cylinder 22 to compress the air within the combustion chamber.

[0029] The fuel is then directed into the combustion chamber and ignited. The engine may be configured as a spark ignition engine or a compression ignition engine. During the expansion stroke, the ignited fuel-air mixture in the combustion chamber expands, causing the piston 24 to move from the top of the cylinder 22 to the bottom of the cylinder 22. The movement of the piston 24 causes a corresponding movement of the crankshaft 26 and provides a mechanical torque output from the engine 20.

[0030] During the exhaust stroke, intake valve 30 remains closed and exhaust valve 34 opens. Piston 24 moves from the bottom of cylinder 22 to the top of cylinder 22 to remove exhaust gas and combustion products from the combustion chamber by reducing the volume of the combustion chamber. Exhaust flows from combustion cylinder 22 to exhaust manifold 36.

[0031] The position and timing of the intake valve 30 and the exhaust valve 34 , as well as the fuel injection timing and the ignition timing, may vary for each engine stroke.

[0032] The crankshaft 26 may be provided with a crankshaft gear 42 or a driving gear. The balance shaft 44 may be provided with a balance gear 46 or a driven gear meshed with the driving gear 42. The crankshaft 26 may have an additional driving gear mounted thereon or a gear train meshed with the driving gear (including a gear train for driving the camshafts 38 and 40, a pump 148 in a cooling system or lubrication system 50 of the engine, a fuel pump, a supercharger or other forced induction system, a vacuum pump, an alternator, etc.) to drive other engine systems or vehicle systems according to the present disclosure.

[0033] Figure 2 According to the embodiment and Figure 1 1 is a perspective view of a crankshaft and balance shaft assembly 100 used with an engine 20 in an inline three-cylinder configuration. Figure 2 The elements in Figure 1 The same reference numerals as similar elements in the figure. In other examples, the crankshaft and / or the engine may have more than one balance shaft. A balance shaft 44 may be provided for an engine having asymmetry. For example, in an engine having one or more cylinders, the movement of the connecting rod throughout the rotation of the crankshaft 26 may be asymmetric. For example, in a given crankshaft rotation time period, the descending and ascending pistons are not always completely opposite or balanced in their movement and acceleration, which generates inertial forces and / or couples or torques (which may increase additionally as the engine and crankshaft speeds increase) in each revolution of the crankshaft. In one example, an inline three-cylinder engine has an inherent second-order couple caused by asymmetric connecting rod movement, and a balance shaft 44 may be required based on the size of the reciprocating cylinder mass. In other examples, an inline four-cylinder engine has an inherent second-order force caused by asymmetric connecting rod movement, and a balance shaft 44 may be required based on the size of the reciprocating cylinder mass. In another example, a six cylinder engine is provided with two in-line cylinder banks in a V configuration and the engine has an inherent second order force couple caused by asymmetric connecting rod motion and one or more balance shafts may be provided for use with the engine.

[0034] The crankshaft 26 is shown as having a driving gear 42 or crankshaft gear coupled to the crankshaft 26 for rotation therewith. A balance shaft 44 extends parallel to the crankshaft 26 and is eccentrically counterweighted. For the balance shaft 44 shown for use with an inline three-cylinder engine, the balance shaft has two eccentric counterweights 102, 104 or equal masses that are oriented 180 degrees or opposite to each other and are set at a specific distance from each other along the length of the balance shaft. In one example, the counterweight 102 is formed as an integral component of the balance shaft 44, and in other examples, the counterweight 102 is connected to the balance shaft 44 for rotation therewith. The second eccentric counterweight can be integrated into and provided by the eccentric counterweight counterweight balancing gear 46 based on (for example) packaging constraints or desired longitudinal spacing between the counterweights 102, 104. The second eccentric counterweight can be divided into two separate smaller parts, both of which are diametrically opposed to the first counterweight 102, wherein one part of the second eccentric counterweight is connected to or integrated into the balance shaft and the other part of the second eccentric counterweight is integrated into the eccentric counterweight balance shaft. Optionally, the second eccentric counterweight can be supported separately by the balance shaft 44. The mass and relative distance of the eccentric counterweights depend on the level of the force couple that needs to be balanced. In other examples, the size and positioning (radial and longitudinal) of the counterweights on the balance shaft can be determined based on the level of the force that needs to be balanced.

[0035] The balance shaft 44 has a driven gear 46 or balance gear connected to the balance shaft 44 for rotation therewith. The driving gear 42 of the crankshaft meshes with the driven gear 46 of the balance shaft so that the rotation of the crankshaft 26 drives the balance shaft 44. The driving gear 42 and the driven gear 46 can be selected to provide a desired gear ratio and provide a transmission ratio of the balance shaft compared to the crankshaft. The driving gear 42 and the driven gear 46 are configured as mutually meshing spur gears or mutually meshing helical gears. In some embodiments, the driving gear 42 and the driven gear 46 are further configured as scissor gears to provide a biasing force to keep the gears engaged. According to one example, for a gear train that uses scissor gears to prevent gear teeth from separating under high torsional excitation, gear whine noise may increase due to even greater contact forces between meshing gear teeth.

[0036] Figure 2The driven gear 46 or balance gear according to the present disclosure is counterweighted to provide balance to the engine. The balance gear 46 can be counterweighted to provide counterweight to the balance shaft assembly by itself and by utilizing a uniformly weighted balance shaft 44 or a balance shaft 44 combined with an eccentric weight. In one example, the balance gear 46 is counterweighted based on packaging constraints on the balance shaft 44 in the engine compartment. By counterweighting the balance gear 46, additional NVH considerations may arise in the system, including gear whine and rattle, wherein rattle includes vibrations in the gear center distance caused by the inertia of the unbalanced mass, noise caused by gear skew and tilt generated by the dynamic characteristics of the balance shaft.

[0037] Figures 3 to 5 A balance shaft assembly 150 including a driven gear 46 according to the present disclosure is shown. The balance shaft assembly 150 may be used with Figure 1 The engine 20 is used together with or Figure 2 For simplicity, Figures 3 to 5 The elements in are given Figure 1 to Figure 2 4. Like elements in the same reference numerals. It is contemplated that the driven gear 46 described herein may be used as a counterweight gear or a gear in other vehicle applications to react to gear whine associated with gear deflection. The driven gear 46 is connected to the nose 152 of the balance shaft 44. The driven gear 46 is counterweighted or eccentrically counterweighted to provide counterweight to the balance shaft 44 or to provide additional counterweight to the balance shaft 44. The balance gear 46 according to the present disclosure integrates a particle damper 154 or pellet damper into the side (flank) 156 of the gear in the counterweight area 158 or into the unbalanced mass of the gear. The balance gear may be a first-order balance shaft gear. The pellet damper 154 has a plurality of particles 160 or pellets, which may be provided by small steel balls disposed inside a container (formed by the gear 46). The energy generated by the deflection mode of the gear 46 is dissipated through friction losses, collisions between beads, and collisions between beads and the gear wall. The pellet damper 154 provides broadband dissipation of noise, vibration and harshness (NVH) and is not tuned to a specific frequency. The particle damper 154 is integrated into a groove 162 or recess formed in the balance weight section 158 of the balance gear 46, and the size of the components of the particle damper 154 can be adjusted to maintain the initial weight of the balance weight of the balance gear 46. By integrating the damper 154 into the balance gear, NVH, including gear whine, can be controlled and mitigated at the source. In addition, the balance gear 46 described herein with an integrated damper 154 is suitable for use in harsh environments, for example, engine compartments with high temperatures and circulating lubrication, where other conventional dampers such as those containing rubber materials may not be suitable.

[0038] like Figure 3 As shown, the balancing shaft has balancing weights 102, 104 arranged diametrically opposite to each other and spaced longitudinally along the balancing shaft 44. The second balancing weight is divided so that a portion of the balancing weight 104 is formed together with the balancing shaft and another portion of the balancing weight 104 is provided by the balancing gear 46 to be balanced. In other examples, the balancing weights 102, 104 can be arranged separately as described above, and the size and positioning can be adjusted as needed to balance the forces or couples of the associated engine configuration. The driven gear 46 or balancing gear is formed by a wheel disc 164 or a wheel disc member having a first side 166 and a second side 168 opposite to each other. The wheel disc member 164 and the first side 166 and the second side 168 extend radially outward from the central hole 170 to a peripheral edge 172 of the wheel disc. The peripheral edge 172 of the wheel disc extends between the first side 166 and the second side 168 of the wheel disc and provides the outer periphery of the balancing gear 46. The outer peripheral edge 172 defines a series of gear teeth 174, and the gear teeth can be configured for spur gears, helical gears, or other gear types. In one example, as shown, the peripheral edge 172 extends generally perpendicular to the first side 166 and the second side 168 and parallel to the central hole 170. In other examples, the peripheral edge 172 can be inclined relative to the first side 166 and the second side 168 and the central hole 170, for example, a bevel gear.

[0039] The body or gear side of the balance gear 46 has a first sector 176 and a second sector 178. In one example, the first sector 176 and the second sector 178 cooperate to provide a 360-degree body, so that they are the only two sectors of the gear 46. The first sector 176 and the second sector 178 are generally opposite to each other. In one example, the first sector 176 ranges from 140 degrees to 220 degrees of the wheel disc, and the second sector 178 provides the remaining 220 degrees to 140 degrees of the wheel disc, respectively. In another example, the second sector 178 can be less than 140 degrees. In another example, each sector 176, 178 can provide half a wheel disc for the wheel disc.

[0040] The first sector 176 of the wheel disc has at least one hole 180 formed through the first sector 176 and intersecting the first side 166 and the second side 168. In other examples, as shown, the first sector 176 of the wheel disc has a series of holes 180 formed through the first sector 176 to intersect the first side 166 and the second side 168 of the disc. The holes 180 of the first sector 176 extend radially outward from the central hole 170 to remove mass from the wheel disc 164 away from the longitudinal axis or rotational axis 182 of the gear. In other examples, the holes 180 in the first sector 176 can be replaced by a recess or groove that intersects one of the first side 166 and the second side 168, or be configured to be combined with a recess or groove that intersects one of the first side 166 and the second side 168 to remove material from the body of the balance gear 46 in the first sector 176 away from the rotational axis 182.

[0041] The second sector 178 of the wheel disc is provided with an internal particle damper 154 or pellet damper formed therein. The body of the wheel disc 164 has a groove 162 or indentation formed therein and intersecting one of the first side 166 and the second side 168. In the example shown, the indentation 162 intersects the first side 166 of the wheel disc. The indentation 162 or groove is formed by the gear side 156 or body in the second sector 178.

[0042] The balancing gear 46 has a cover plate 184 connected to the first side 166 of the balancing gear 46 to close the recess 162. The cover plate 184 can be connected or bonded to the balancing gear 46 using fasteners that cooperate with a sealing member (such as an O-ring, a room temperature vulcanized (RTV) silicone gasket, or another gasket material with suitable temperature resistance). The cover plate 184 can be selectively connected to the first side 166 of the balancing gear 46 by welding or another similar process. The cover plate 184 and the wheel plate 164 cooperate to form a fluid seal, for example, to prevent lubricants or other fluids from entering the damper 154 during use. The cover plate 184 can be provided with a certain thickness, the thickness of which is sized to provide a predetermined mass and weight to the cover plate 184 and to keep the unbalanced mass 158 of the gear 46 unchanged compared to a conventional counterweighted balancing gear without the damper 154.

[0043] The mating surface 186 may be defined by the first side 166 and extend around the perimeter of the recess 162 and be proximate to the recess 162. The mating surface 186 may be recessed from the first side 166 and sized to receive the cover plate 184. In one example, the mating surface 186 may be recessed so that the outer surface 188 of the cover plate 184 is flush or coplanar with the adjacent first side 166 of the wheel in the second sector 178 when installed, or to reduce the protrusion of the cover plate 184 from the first side 166 of the gear. The mating surface 186 may additionally be provided with a groove or other feature to accommodate a sealing member, and may have a threaded hole intersecting the mating surface to accommodate a fastener for connecting the cover plate to the balance gear.

[0044] The recess 162 may be formed as an impermeable groove or recess in the wheel disc 164 such that the recess is formed by an end wall 190 and a side wall 192. The end wall 190 is spaced apart from the second side 168 of the wheel disc and may be parallel to the first side 166 and the second side 168 of the wheel disc. The side wall 192 intersects the first side 166 of the wheel disc and extends from the end wall 190 to the first side 166 or to the mating surface 186 of the wheel disc. In various embodiments, and as shown, the recess 162 is provided as the only recess 162 in the wheel disc to accommodate particles and is closed by a cover plate so that the balance gear 46 has a single particle damper 154 formed therein.

[0045] Before the cover plate 184 is connected to the balance gear 46, a plurality of particles 160 are placed in the recess 162. The plurality of particles 160 can be provided by pellets and can be in the shape of spherical beads. The plurality of particles 160 or pellets can be formed of a metal or metal alloy, respectively. In the example shown, the pellets are provided by steel balls, which have the material properties required for repeated collisions and high operating temperatures and a density that contributes to the unbalanced mass of the gear.

[0046] The cover plate 184 and the recess 162 cooperate to limit the internal volume of the damper 154 or the container for the particles 160. The size of the damper 154 is adjusted to improve the NVH performance by controlling the size or diameter of the particles 160 or pellets, the size and shape of the damper 154 container, the position of the container and the damper 154 on the gear 146, and the void or empty volume of the damper 154 filled with pellets (referred to as the fill rate). The main factors affecting the performance of the damper 154 can be the volume of the damper and the void or fill rate of the damper. The damper 154 is generally arranged in the gear to be close to the deformation area (e.g., radially outward) and away from the rotation axis 182 of the gear. Generally, the performance of the damper 154 increases with the increase of the volume of the damper 154.

[0047] The container is sized so that the volume of the container ranges from 10% to 40% of the volume of the counterweight in the gear. In one example, the volume of the damper 154 is between 4 and 12 cubic centimeters. The damper 154 can be provided as a single damper 154 to provide the largest continuous volume for the damper in the gear 46 and to improve performance and noise reduction. In other embodiments, multiple dampers 154 can be incorporated into the counterweight balancing area 158 of the gear based on other gear design constraints. The shape of the recess and damper container can also be changed. In this example, the damper 154 has a cross-sectional shape of an annular sector to provide a large volume based on the gear shape and to set the damper 154 away from the central hole 170 and the rotation axis 182 of the gear. The damper 154 is shown as having a constant depth or distance between the first side 166 and the end wall 190, however, in other examples, the depth of the damper 154 can be varied, for example, with an inclined, curved or V-shaped end wall 190. In other examples, the damper 154 may have other cross-sectional shapes, including circular, semicircular, triangular, square, rectangular, polygonal, and complex shapes including convex and concave arcs. Examples of alternative concave and damper shapes and sizes are shown in FIG. Figure 6 and Figure 7 Shown in.

[0048] Return to reference Figures 3 to 5 , pellets 160 may have a diameter ranging from less than 1 mm to 5 mm. In one example, pellets 160 have a diameter from half a millimeter to 2 mm. In another example, each pellet 160 has a volume that is an order of magnitude less than a volume of the enclosed damper.

[0049] A predetermined number or volume of particles 160 is disposed in the recess 162. In one example, as a filling rate, the number or volume of particles 160 is set so that they fill 70% to 95% or 80% to 90% of the volume of the closed damper 154, or fill up to 90% of the volume of the damper. In other words, 10% to 20% of the volume of the damper is left as unfilled space or open space.

[0050] The series of holes 180 in the first sector 176 and the damper 154 in the second sector 178 cooperate to provide an eccentric counterweight for the balance gear 46. Because the first sector 176 has less structure than the second sector 178, the balance gear 46 has an increased degree of flexure. This flexure can cause the gear 46 to move during rotation and can provide a second or higher order degree of gear motion, for example, a "potato chip" shape or something like a hyperbolic parabola or other saddle or complex shape. Because the gear 46 is subject to some degree of flexure or movement, the forces between the intermeshing teeth between the crankshaft gear and the balance gear will likely vary and change and may increase or amplify the whine. For gears with Figures 3 to 5 For a conventional counterweight balancing gear having the same weight and mass distribution as the balancing gear 46 of the present invention, the modeling results show that the flexure modes of the gear 46 contribute to the dynamic amplification of the gear whine excitation generated at the gear meshing and contribute to their transmission performance to the mating components. The modeling results indicate that the frequency spectrum of the measured engine balance shaft 44 gear whine noise increases and has resonance in the frequency range of 3000 Hz to 4500 Hz, which corresponds to the modeling results showing the flexure modes of the gear 46 in this whine frequency range and the higher order mode shape or "potato chip" shape of the gear.

[0051] Figure 8 2 shows a graph of acoustic inertance versus frequency for a balance gear for various balance weights based on modeling results. A conventional balance gear formed without a particle damper is shown at line 220 and compared to a conventional balance gear shown at line 222. Figures 3 to 5 The conventional balance gear is compared with the balance gear 46. Figures 3 to 5 The gears have the same weight and mass distribution. Figure 8 As can be seen in FIG. 2 , the pellet damper gear provides a reduction in the peak or resonant frequency at 222 where the bandwidth of the noise is reduced, without introducing new resonant frequencies. Note that alternative means of damping the balanced gear (e.g., by attaching a tuned mass damper as shown by line 224) will reduce the central peak at 226; however, two new smaller peaks may be created, and the damping provided by the tuned mass damper may vary with temperature, such that temperature changes may cause one of the two peaks to increase.

[0052] For example, a gear 46 having an integrated particle damper 154 formed in a counterweight section provides a number of advantages over a gear without a damper 154 or a gear having a tuned mass damper connected to the gear. For example, the performance of the pellet damper 154 is generally insensitive to temperature and temperature variations, so it is suitable for use inside an engine and at engine operating temperatures. In contrast, a tuned mass damper may be sensitive to temperature. Integrating the pellet damper 154 into the gear 46 does not affect the functional requirements of the gear (such as gear center distance variation, gear slope, gear skew, etc.). The particle damper provides gear whine reduction and NVH improvement over a broadband frequency range, while the tuned mass damper targets a narrow frequency range for NVH reduction. The integrated pellet damper 154 is also easy to implement and provides a less complex solution compared to other engine gear whine mitigation means (engine acoustic treatment and wrapping and gear micro geometry requirements). Furthermore, the integrated pellet damper 154 does not impact packaging requirements and shaft space (which may be limited) for the gear 46 and provides the same overall weight and mass distribution as a conventional undamped counterweighted balance gear.

[0053] Fig. 9 A method 250 of forming a gear, such as a balanced gear, is shown. The method 250 may have a greater or lesser number of steps than shown, and the steps may be rearranged to be performed in another order.

[0054] At step 252, a wheel disc 164 is formed having opposing first and second sides 166 and 168 extending radially outward to a circumferential edge 172. The wheel disc may be formed by forging, die casting, net or near net die casting, investment casting, or the like. The wheel disc may require heat treatment such as sintering or other processes. Since a machined surface for the hole is not required, the hole 180 in the first sector may be provided and formed when the gear is formed. The hole 180 may be formed to extend through the wheel disc and intersect the first and second sides of the wheel disc.

[0055] At step 254, a series of gear teeth 174 are formed into the circumferential edge 172 of the wheel disc. The gear teeth may be formed or further defined by machining including gear cutting, hobbing, gear forming, milling, or broaching. The gear teeth of the gear may be further heat treated to increase their wear resistance and harden them. The wheel disc 164 may also be machined using honing or another process to form the center hole 170, and the wheel disc 164 may be milled to form the mating surface 186 of the wheel disc. If the hole 180 was not formed in the first sector when the wheel disc was formed, the hole may be machined into the first sector of the gear during this step.

[0056] At step 256, a single recess 162 of the damper 154 is formed into the wheel disc by recessing a non-through depth that intersects and extends into the first side of the wheel disc 164. The recess 162 extends adjacent to the circumferential edge of the wheel disc so that the recess is spaced from the axis of rotation 182 of the gear and away from the central hole 170. The recess 162 may be formed when the gear wheel disc is formed (e.g., during casting), or may be machined into the gear wheel disc. The recess 162 is formed so that it is in the second sector of the wheel disc and radially opposite the plurality of holes 180.

[0057] At step 258, a plurality of pellets 160 of a specified volume are placed into the recess 162 to achieve a specified fill rate. In one example, the fill rate is 80% to 90% of the volume of the enclosed damper 152. The placed pellets 160 are also formed with a specified diameter. In one example, the diameter is 1 to 2 millimeters. The internal volume of the damper 154, the specified fill rate, and the diameter of the pellets 160 are sized to dampen the squeal caused by at least second order deformation of the balance gear 46.

[0058] At step 260, a cover plate 184 is attached to the first side 166 of the wheel disc to close the recess 162, retain the plurality of pellets 160 therein, and form an internal damper 154 in the balance gear 46. The cover plate 184 may be welded to the wheel disc to seal the recess and form the damper. Alternatively, a sealing member may be disposed between the cover plate 184 and the wheel disc 164, and fasteners may be used to connect the cover plate to the wheel disc and form the damper 154.

[0059] Although exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the present disclosure. Rather, the words used in the specification are descriptive rather than restrictive, and it should be understood that various changes may be made without departing from the spirit and scope of the present disclosure. In addition, the features of the various implemented embodiments may be combined to form further embodiments of the present disclosure.

Claims

1. A balancing gear for a vehicle axle, comprising: a wheel disc having opposing first and second sides extending radially outwardly to an edge defining a series of gear teeth, the wheel disc having a first sector defining at least one aperture therethrough and a second sector defining a recess intersecting the first side; a plurality of particles disposed in the recess; a cover plate connected to the first side of the wheel disc to close the recess, The cover plate, the recess and the plurality of particles cooperate with each other to form a damper for the balancing gear, and the balancing gear is eccentrically weighted by the at least one hole and the damper.

2. The balance gear according to claim 1, wherein: The first sector and the second sector are opposite to each other so that the balancing gear is balanced by the counterweight.

3. The balance gear according to claim 1, wherein: The recess and the cover plate cooperate to define a certain volume therebetween, and wherein the certain volume ranges from 10% to 40% of the volume of the second sector.

4. The balance gear according to claim 3, wherein: The diameter of each particle of the plurality of particles is on the order of a thousand times smaller than the certain volume.

5. The balance gear according to claim 3, wherein: The plurality of particles is provided to fill between 70% and 90% of the certain volume.

6. The balance gear according to claim 1, wherein: The outer surface of the cover plate and the first side of the wheel disc are coplanar with each other.

7. The balance gear according to claim 1, wherein: The wheel disc defines a recess having an end wall spaced from the second side of the wheel disc and a side wall intersecting the first side of the wheel disc.

8. The balancing gear according to claim 7, wherein: The end wall extends parallel to the second side of the wheel disc.

9. The balancing gear according to claim 1, wherein: The recess is the only recess in the wheel disc that accommodates the particles and is closed by the cover plate.

10. An engine system comprising: a crankshaft gear coupled to a crankshaft of the engine for rotation therewith; The balancing gear according to any one of claims 1 to 9 is coupled to the balancing shaft for rotation together with the balancing shaft, the balancing gear being meshed with the crankshaft gear.

11. The engine system of claim 10, wherein: The balance shaft has an eccentric weight connected to the balance shaft for rotation with the balance shaft; The damper of the balancing gear is radially opposite to the eccentric counterweight.

12. The engine system of claim 10, further comprising: A sealing member is disposed between the cover plate and the wheel disc to seal the recess.

13. The engine system of claim 10, wherein: The plurality of particles includes steel shot.

14. A method of forming a balance gear for a vehicle balance shaft, comprising: forming a wheel disc having opposing first and second sides extending radially outwardly to a circumferential edge; forming a series of gear teeth on the circumferential edge; forming a single recess into the wheel disc, the recess intersecting the first side of the wheel disc and extending to a non-through depth into the wheel disc, the recess extending adjacent to the circumferential edge; forming at least one hole in the wheel disc, the at least one hole intersecting the first and second sides of the wheel disc and diametrically opposite the recess; placing a plurality of pellets into the recess to achieve a specified fill rate; attaching a cover plate to the first side of the wheel disc to close the recess, retain the plurality of pellets in the recess, and form an internal damper in the balance gear; wherein the volume of the internal damper, the specified filling ratio and the diameter of the pellets are designed to damp the whine caused by at least second order deformation of the balancing gear, and Wherein, the balancing gear is eccentrically weighted by the at least one hole and the internal damper.

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