Dampers for crankshafts of reciprocating engines and reciprocating engines comprising the same

A damper for a crankshaft of a reciprocating engine includes an inner shell and an inertia ring, the inner shell and the inertia ring having a plurality of teeth and grooves that are intermeshed with one another. The damper further includes a plurality of damping pads positioned between the teeth of the inner shell and the grooves of the inertia ring. The inertia ring is constrained from translating in the axial direction and the radial direction with respect to the inner shell and is rotatable with respect to the inner shell in the circumferential direction through a constrained range by compressing the damping pads.

TECHNICAL FIELD

The present specification generally relates to dampers for crankshafts and, more specifically, to dampers having limited circumferential movement between an inertia ring and an inner shell coupled to the crankshaft.

BACKGROUND

In internal combustion engines, the engine crankshaft translates power generated in the combustion and expansion strokes of the engine cylinders and converts the power to torque. The torque output from the engine is delivered from the crankshaft through a torque transmission device to provide motive force. For example, in a motor vehicle, the crankshaft provides torque to the drivetrain of the vehicle; in a marine vehicle, the crankshaft provides torque to a propulsion system; in a power generation device, the crankshaft provides torque to a rotor that rotates within a stator.

Throughout operation of the engine, the torque applied to the crankshaft varies due to, for example, periodic firing of the engine's cylinders, variation in the crankshaft rotational speed, and engagement and disengagement of transmission elements. These torque variations may create torsional vibrations in the crankshaft that may tend to periodically twist the crankshaft. Twisting of the crankshaft by the torque variations may increase vibrations that are imparted to the transmission elements, which may increase bearing wear, as well as adversely affect engine timing caused by variations in the piston position relative to the end of the crankshaft. Further, twisting of the crankshaft may increase mechanical stress in the crankshaft itself, which may lead to failure of the crankshaft.

Accordingly, dampers for crankshafts of reciprocating engines may be desired to mitigate torsional vibrations in the crankshafts.

SUMMARY

In one embodiment, a damper for a crankshaft includes an inner shell having a body portion, a cover flange extending in a circumferential direction around an end face of the body portion, and a plurality of teeth extending in a radial direction from the body portion. The damper also includes an inertia ring having a plurality of grooves extending in the radial direction, the inertia ring positioned proximate to the inner shell such that grooves of the inertia ring intermesh the teeth of the inner shell. The inertia ring further includes a plurality of damping pads positioned between the teeth of the inner shell and the grooves of the inertia ring. The inertia ring is constrained from translating in the axial direction and the radial direction with respect to the inner shell and is rotatable with respect to the inner shell in the circumferential direction through a constrained range by compressing the damping pads.

In another embodiment, a damper for a crankshaft includes an inner shell having a body portion, a cover flange extending in a circumferential direction around an end face of the body portion, and a plurality of teeth extending in a radial direction from the body portion. The damper also includes an inertia ring comprising a plurality of grooves extending in the radial direction, where the inertia ring is positioned proximate to the inner shell such that grooves of the inertia ring intermesh the teeth of the inner shell. The damper further includes a plurality of damping pads positioned between the teeth of the inner shell and the grooves of the inertia ring and an outer shell extending around at least a portion of the inertia ring in the circumferential direction. The inertia ring is constrained from translating in the axial direction and the radial direction with respect to the inner shell and is rotatable with respect to the inner shell in the circumferential direction through a constrained range by compressing the damping pads.

In yet another embodiment, a reciprocating engine includes a crankshaft assembly having a plurality of pistons adapted to reciprocate in a radial direction, a crankshaft adapted to rotate in a circumferential direction, a plurality of connecting rods coupling one of the plurality of pistons to the crankshaft, and a damper coupled to the crankshaft. The damper includes an inner shell having a body portion, a cover flange extending in the circumferential direction around an end face of the body portion, and a plurality of teeth extending in the radial direction from the body portion. The damper also includes an inertia ring having a plurality of grooves extending in the radial direction, where the inertia ring is positioned proximate to the inner shell such that grooves of the inertia ring intermesh the teeth of the inner shell. The damper further includes a plurality of damping pads positioned between the teeth of the inner shell and the grooves of the inertia ring and an outer shell extending around at least a portion of the inertia ring in the circumferential direction. The inertia ring is constrained from translating in the axial direction and the radial direction with respect to the inner shell and is rotatable with respect to the inner shell in the circumferential direction through a constrained range by compressing the damping pads.

DETAILED DESCRIPTION

Dampers according to the present disclosure generally include an inner shell, an inertia ring, and a plurality of damping pads. The inner shell has a plurality of teeth extending in a radial direction from a body portion. The inertia ring has a corresponding number of grooves that extend in the radial direction. The grooves of the inertia ring intermesh with the teeth of the inner shell and the damping pads are positioned between the teeth and the grooves. The inertia ring is constrained from moving in the radial and axial directions while being rotatable relative to the inner shell in the circumferential direction through a constrained range. The damping pads are compressible and allow the inertia ring to be rotate relative to the inner shell. The damping pads also absorb vibration introduced to the damper through the inner shell. Various embodiments of the dampers and reciprocating engines incorporating the dampers will be described in more detail herein.

FIG. 1generally depicts a crankshaft assembly for an internal combustion engine, including a crankshaft and a plurality of pistons coupled to the crankshaft through connecting rods. The crankshaft assembly is mounted in an engine block (not shown), and may be incorporated into a variety of vehicles or equipment including, for example and without limitation, motor vehicles, airplanes, marine vehicles, rail vehicles, power generation equipment, and the like. The crankshaft assembly includes a transmission element coupled to a first end of the crankshaft and a damper coupled to a second end of the crankshaft. Power generated by the pistons is captured by the crankshaft, which directs torque through the transmission element. The power generated by the pistons may vary due to quantity of fuel combusted in the combustion chambers, the periodic firing of the engine cylinders, variation in crankshaft rotational speed, and engagement and disengagement of transmission elements, which may induce twisting or vibrations into the crankshaft. The damper absorbs and dissipates the twisting and/or vibrations from the crankshaft, such that mechanical stresses in the crankshaft are reduced. Further, the damper according to embodiments described herein is resistant to wear, such that operation of the damper may be maintained at elevated crankshaft rotational speeds and at high crankshaft acceleration rates for extended durations.

As used herein, axial direction70, circumferential direction72, and radial direction74refer to directions oriented with respect to orientation of rotation of the crankshaft92. During engine operation, the crankshaft92rotates about a longitudinal axis, which is used herein to define the axial direction70. The direction of rotation of the crankshaft92also defines the circumferential direction72(the direction around the axial direction70), and the radial direction74(the direction perpendicular to the axial direction70).

Referring toFIG. 1in detail, the reciprocating engine80includes a plurality of pistons82that are adapted to reciprocate within cylinders of an engine block (not shown), as is conventionally known. The pistons82are coupled to a crankshaft92through connecting rods84to form a crankshaft assembly90. The crankshaft92includes a plurality of offset lobes, to which the connecting rods84are attached. The crankshaft assembly90also includes a transmission device86coupled to the crankshaft92and a damper100coupled to the crankshaft92. As depicted inFIG. 1, the crankshaft assembly90may also include a timing drive94coupled to the crankshaft92. The timing drive94may be coupled to various components of the reciprocating engine80that rotate at a speed relative to the crankshaft92. For example, the cam shafts of the reciprocating engine that are responsible for actuating the valvetrain of the reciprocating engine80may be coupled to the timing drive94. The transmission device86is positioned proximate to a first end of the crankshaft92, and may be positioned along a portion of the crankshaft92that extends outside of the engine block (not shown). The transmission device86transmits torque from the crankshaft92, and therefore the reciprocating engine80, to provide motive force. Such transmission devices86may include, for example and without limitation, a flywheel, a torque converter, a clutch element, and the like. In the embodiment depicted inFIG. 1, the damper100is positioned proximate to a second end of the crankshaft92opposite the first end, and may be positioned along a portion of the crankshaft92that extends outside of the engine block (not shown).

The top surface of each of the pistons82, along with the cylinders and cylinder heads (not shown), define a plurality of combustion chambers, in which an air-fuel mixture is introduced, compressed, ignited, expanded, and exhausted. After the air-fuel mixture is ignited, pressure inside the combustion chamber rises, pushing the piston82towards the crankshaft assembly90. As the pistons82translate towards the crankshaft assembly90, the connecting rods84transfer force from the increased pressure to the crankshaft assembly90, thereby providing the crankshaft assembly90with torque.

Transfer of force from each of the pistons82is not uniform within a single rotation of the crankshaft92, however, as the pistons82within the reciprocating engine80only apply force to the crankshaft92in the expansion stroke of the reciprocating engine80. Further, multiple pistons82are coupled to the crankshaft92in the axial direction70. The air-fuel mixture in each of the combustion chambers defined by the pistons82are periodically ignited in the ignition stroke, in a so-called firing pattern. Because the ignition and expansion strokes deliver force to the crankshaft92according to the firing pattern, force applied to the crankshaft92is periodic and alternating in the axial direction70at any given point in the operating cycle of the reciprocating engine80. Further, as the reciprocating engine80is operated, some of the pistons82translate towards the crankshaft92in the expansion stroke and/or the intake stroke, while other pistons82translate away from the crankshaft92in the exhaust stroke and/or the compression stroke. The forces applied to the crankshaft92by the pistons82in the expansion stroke may be in an opposite circumferential direction72to the forces applied to the crankshaft92during the ignition and expansion strokes. These forces may cause the crankshaft92to rotate in the circumferential direction72, as to transmit torque to the transmission device86. These forces may also cause the crankshaft92to twist in the circumferential direction72away from a neutral orientation of the crankshaft92. Subsequently, the crankshaft92rebounds towards the neutral orientation.

The variations in the magnitude and the position in the axial direction70of the forces applied to the crankshaft92during reciprocating engine80operation may induce vibrations into the crankshaft92. Such vibrations may increase the wear rate of bearings (not shown) that support the crankshaft92at positions in the axial direction70. The vibrations may also induce mechanical stress into the crankshaft92, which may decrease the usable life of the crankshaft92. Further, the vibrations may modify the position of the pistons82relative to the timing drive94, which regulates operation of components that control the timing of ignition in the reciprocating engine80. The resultant modification of the timing of ignition relative to the position of the pistons82may decrease power output of the reciprocating engine80.

To mitigate these vibrations, a damper100is coupled to the crankshaft92. The damper100absorbs the vibrations associated with the variations in mechanical forces applied to the crankshaft92. Some portions of the damper100maintain a clocking orientation with the crankshaft92of the reciprocating engine80, while other portions of the damper100are permitted to vary in clocking orientation relative to the crankshaft92. The variation in clocking orientation of the portions of the damper100may absorb vibrations induced to the crankshaft92. In some embodiments, the inertia of the damper100may modify a resonant frequency of the crankshaft92, such that the resonant frequency of the crankshaft92is not within the operating speed range of the reciprocating engine80. In some embodiments, vibrations of the crankshaft92are damped by the damper100by dissipating the mechanical vibratory energy.

Referring now toFIGS. 2-6, one embodiment of the damper100is depicted. In this embodiment, the damper100includes an inner shell120, an outer shell110, an inertia ring130, and a plurality of damping pads140. As depicted inFIG. 2, the inner shell120has a body portion122that includes a hub portion129and a plurality of teeth128that extend in the circumferential direction from the hub portion129around the body portion122. In the embodiment depicted inFIGS. 2-6, the teeth128are parallel key splines in which sides of the teeth128are parallel to one another, and are generally parallel with a centerline of an individual tooth128extending in the radial direction.FIG. 3is a sectional view of the damper100that is centered on a tooth128of the inner shell120;FIG. 4is a section view of the damper100that is centered between the teeth of the inner shell120. Other shapes of the teeth128, including involute and serrated splines, may be incorporated into the damper100without departing from the scope of the present disclosure.

As further depicted inFIG. 3, the inner shell120also includes a mounting flange portion123extending radially inward from the body portion122. The mounting flange portion123includes a plurality of fastener openings126through which fasteners may be inserted to couple the inner shell120to the crankshaft92, as depicted inFIG. 1.

Referring again toFIG. 3, the inner shell120further includes a capture lip124that extends radially outward from the top surface of the teeth128. As shown inFIG. 3, the capture lip124extends from the body portion122of the inner shell120in a circumferential direction around an end face of the body portion122. The capture lip124limits translation of the inertia ring130in the axial direction70away from the crankshaft92(depicted inFIG. 1).

Referring toFIG. 2-4, the damper100also includes an inertia ring130having an engagement portion132and an inertial portion138. The engagement portion132includes a plurality of grooves136extending in the radial direction. The plurality of grooves136extend to a groove valley139in the inertia ring130. In the depicted embodiment, the number of grooves136in the inertia ring130corresponds to the number of teeth128in the inner shell120. When the damper100is assembled, the inner shell120is positioned proximate to the inertia ring130such that the grooves136of the inertia ring130at least partially surround the teeth128of the inner shell120. The teeth128of the inner shell120and the grooves136of the inertia ring130are thereby intermeshed with one another.

Embodiments of the damper100according to the present disclosure may also include an outer shell110. The outer shell110extends around at least a portion of the inertia ring130in the circumferential direction. As shown inFIG. 3, the outer shell110extends around at least a portion of the inertia ring130in the circumferential direction such that the outer shell110at least partially encapsulates the inertia ring130. As depicted inFIG. 3, the outer shell110includes a flange portion112that extends in a generally radial orientation and a can portion114that extends from the flange portion112in a generally axial orientation. The flange portion112includes a plurality of fastener openings116through which fasteners may be inserted to couple the outer shell110and the inner shell120to the crankshaft. The can portion114of the outer shell110may surround all of the inertia ring130in the circumferential direction over the length of the inertia ring130in the axial direction. The outer shell110may serve as a scatter shield to ensure containment of damper components in the event of failure of one or more damper components. The outer shell110may also limit translation of the inertia ring130relative to the inner shell120in the radial direction74, as will be discussed further below.

A series of timing indications (not shown) may be positioned along the outer diameter of the can portion114of the outer shell110. When the damper100is mounted on the crankshaft92, the timing indications are fixed in position relative to the crankshaft92, and provide an indication of the crankshaft rotational orientation. Reliable reference of the rotational location of the crankshaft92may be beneficial for technicians manufacturing or adjusting the reciprocating engine80.

The inner shell120, the inertia ring130, and the outer shell110may be manufactured from a variety of materials including, for example and without limitation, iron or ferrous alloys, aluminum or aluminum alloys, nickel or nickel alloys, lead or lead alloys, tungsten or tungsten alloys, and uranium or uranium alloys. In some embodiments, the inner shell120, the inertia ring130, and the outer shell may be manufactured from polymer or polymer reinforced composite, for example, nylon, polyester, epoxy, or polycarbonate, which may include glass, carbon, or metallic particles which increase the strength of the polymer.

The mass and geometric shape of the inertia ring130define a polar moment of inertia of the inertia ring130as evaluated in circumferential direction72of the crankshaft92rotating about the axis of rotation of the crankshaft92(seeFIG. 1). Similarly, the mass and geometric shape of the inner shell120and the outer shell110may define a polar moment of inertia of the inner shell120and the outer shell110, respectively. The respective polar moments of inertia of the inertia ring130and the inner shell120may be selected to suit particular parameters of an engine design, including the engine's cylinder configuration, crankshaft stiffness, polar moment of inertia, and mass, the crankshaft assembly polar moment of inertia and mass, combustion chamber pressure change rate, and the like. Because of the variety of variables that affect selection of mass and polar moment of inertia of the inner shell120and the inertia ring130, mechanical design of the inner shell120and the inertia ring130may vary without departing from the scope of the present disclosure. In the embodiments described herein, the polar moment of inertia of the inertia ring130is greater than the polar moment of inertia of the inner shell120. In embodiments of the damper100, the polar moment of inertia of the inertia ring130may be at least three times the polar moment of inertia of the inner shell120. In the embodiment depicted inFIGS. 2-6, the polar moment of inertia of the inertia ring is approximately 4.8 to 6 times the polar moment of inertia of the inner shell120. In some embodiments, the polar moment of inertia of the inertia ring130is greater than about 10% of the polar moment of inertia of the crankshaft92, for example, about 22% of the polar moment of inertia of the crankshaft92. In some embodiments, the polar moment of inertia of the inertia ring130is greater than about 8% of the polar moment of inertia of the crankshaft assembly90, for example, about 11% of the polar moment of inertia of the crankshaft assembly90.

The mass and polar moment of inertia of the damper100may also modify the fundamental and harmonic vibratory frequencies of the crankshaft assembly90. By increasing the mass of the crankshaft assembly90, the damper100may change the fundamental and natural excitation frequencies of the crankshaft92itself. In some embodiments, the fundamental and/or the harmonic vibratory frequencies may be shifted away from the rotational operating speeds of the reciprocating engine80, thereby mitigating any detrimental effects of the frequencies. Specifically, shifting the fundamental and/or natural excitation frequencies of the crankshaft92may allow for the reduction of excitation stresses at the natural excitation frequencies of the crankshaft92, thereby reducing the likelihood of high-cycle fatigue of the crankshaft92within the operating speed envelope of the reciprocating engine80.

Referring toFIGS. 2 and 5, the damper100further includes a plurality of damping pads140positioned within gaps between the grooves136of the inertia ring130and the teeth128of the inner shell120. As depicted inFIG. 5, the damping pads140may include contact portions142that are positioned proximate to faces of the grooves136and the teeth128that are opposed from one another in the circumferential direction72. The damping pads140may also include bridge portions143that connect adjacent contact portions142. The damping pads140, together with the intermeshed teeth128of the inner shell120and the grooves136of the inertia ring130, limit radial translation of the inertia ring130relative to the inner shell120, while allowing rotation of the inertia ring130relative to the inner shell120over a constrained range in the circumferential direction. In some embodiments, the damping pads140allow rotation of the inertia ring130relative to the inner shell120in a constrained range from about 5° degrees clockwise to about 5° anticlockwise of a neutral orientation. In other embodiments, the damping pads140allow rotation of the inertia ring130relative to the inner shell120in a constrained range from about 3° degrees clockwise to about 3° anticlockwise of the neutral orientation. In yet other embodiments, the damping pads140allow rotation of the inertia ring130relative to the inner shell120in a constrained range from about 2° degrees clockwise to about 2° anticlockwise of the neutral orientation.

The damping pads140may be made from a compliant material that undergoes elastic deformation under an applied load compared to the materials of the inertia ring130and the inner shell120. Examples of such materials include, for example and without limitation, natural or synthetic elastomeric materials including silicone, fluoropolymer elastomers, for example Viton®, nitrile rubbers, butyl rubbers, ethylene propylene rubbers, and the like. The damping pads140may be manufactured in an injection molding operation, for example in a co-molding injection molding operation, that laminates contact portions142of the damping pads140onto at least one of the grooves136of the inertia ring130or onto the teeth128of the inner shell120. In the embodiment of the damper100depicted inFIGS. 2-6, and shown in greater detail inFIG. 5, the contact portions142of the damping pads140are co-molded onto the grooves136of the inertia ring130. The bridge portions143of the damping pads140are co-molded to the groove valley139of the inertia ring130. The bridge portions143are spaced apart from the teeth128of the inner shell120in the radial direction such that the teeth128contact the contact portions142of the damping pads140in the circumferential direction72. In other embodiments, the damping pads140may be co-molded over the entirety of each of the teeth of the inner shell and/or over each of the grooves of the inertia ring (not shown).

While the damping pads may be overmolded or co-molded onto the grooves of the inertia ring or the teeth of the inner shell, the damping pads may be formed as a separate, stand-alone component. By way of example, one embodiment of a collected damping insert240is depicted inFIG. 7. In this embodiment, a plurality of damping pads140, each including contact portions142and bridge portions143of the damping pads140, are coupled to an attachment ring145. The attachment ring145interconnects the damping pads140such that the damping pads140are positioned for assembly between the teeth of the inner shell and grooves of the inertia ring. In such embodiments, all of the damping pads140and the attachment ring145that define the collected damping insert240may be formed in a single-stage injection molding process.

Referring toFIGS. 5 and 6, in some embodiments, the damping pads140may be manufactured such that the contact portions142are deformed from their unconstrained state when the inner shell120is assembled with the inertia ring130. Specifically, the damping pads140may be sized such that inserting the teeth128of the inner shell120into the corresponding grooves136of the inertia ring130deform the contact portions142by squeezing the contact portions142between the teeth128and the grooves136. Restated, the first and second thickness148,149of the undeformed contact portions142(i.e., the damping pads140without the inner shell installed, as depicted inFIG. 6) are greater than the first and second thicknesses146,147of the deformed contact portions142(i.e., the damping pads140with the inner shell120installed, as depicted inFIG. 5). Dimensional fit of the teeth128, grooves136, and the damping pads140that deform the damping pads140from their nominal shape upon assembly of the damper100maintains compression on the contact portions142of the damping pads140in the circumferential direction72across a wide range of operating parameters of the reciprocating engine.

Referring again toFIG. 5, in embodiments of the reciprocating engine80, mechanical vibrations imparted to the crankshaft92tends to modify the clocking orientation of the inner shell120relative to the inertia ring130. In general, the inertia ring130carries moment that resists acceleration. Vibrations of the crankshaft may accelerate the inner shell120relative to the inertia ring130, which may modify the relative positioning of the inner shell120and the inertia ring130.

The re-clocking of the inner shell120relative to the inertia ring130compresses the contact portions142of the damping pad140in the direction of rotation of the inner shell120relative to the inertia ring130and relaxes the contact portions142of the damping pads140in the direction opposite the rotation of the inner shell120relative to the inertia ring130. Rotation of inner shell120in the anti-clockwise direction relative to the inertia ring130compresses contact portions142of the damping pads140positioned in the anti-clockwise direction (i.e., tends to decrease the spacing147) and relaxes (or expands) contact portions of the damping pads140positioned in the clockwise direction (i.e., tends to increase the spacing148).

Further, because the inertia ring130is free to rotate relative to the inner shell120in the circumferential direction72over a constrained range, each of the pairs of damping pads140positioned between the teeth128and the grooves136absorb mechanical force. All of the damping pads140, therefore, absorb mechanical energy to distribute the loads associated with crankshaft vibration and acceleration across all of the teeth128and grooves136of the damper100. By widely distributing the load across all of the teeth128and the grooves136, and their associated damping pads140, wear to individual damping pads140may be minimized and the service life of the damper100extended.

Compression and relaxation of the contact portions142of the damping pads140may absorb the mechanical vibrations from the inner shell120and dissipate the mechanical energy by converting the mechanical energy to heat. Conversion of the mechanical energy of the vibrations to heat reduces the vibratory energy returned to the crankshaft92as the contact portions142of the damping pads140return to their nominal shapes and sizes and the inner shell120rotates in a clockwise direction relative to the inertia ring130. Conversion of mechanical energy to heat may be reflected as reduced spring-back of the contact portions142of the damping pads140, which is related to mechanical properties of the material of which the damping pads140are constructed. Accordingly, materials having desired spring-back rates may be selected for use in the damping pads140based on the desired mechanical energy-to-heat conversion.

Referring again toFIG. 3, some embodiments of the inertia ring130may also include a gland134positioned proximate to the outer diameter of the inertia ring130and extending around the circumference of the inertia ring130. The damper100may also include an o-ring144that is positioned within the gland134. While the depicted embodiment of the damper100includes a single gland134and o-ring144, it should be understood that other embodiments of the damper may include a plurality of glands and o-rings without departing from the scope of the present disclosure. When the inertia ring130is assembled into the outer shell110, the can portion114of the outer shell110compresses the o-ring144, inducing a gripping force between the gland134of the inertia ring130and the can portion114of the outer shell110. The gripping force is induced by the squeeze applied to the o-ring144and may be modified by changing the dimensional fit between the o-ring144, the gland134, and the can portion114. The induced gripping force between the can portion114and the gland134across the o-ring144may increase a resistance to relative rotation between the inertia ring130and the outer shell110in the circumferential direction.

In these embodiments, the o-ring144provides additional or supplemental damping capabilities to the damping pads140. The o-ring144positioned between the inertia ring130and the can portion114of the outer shell110dissipates mechanical energy from the damper100in association with the damping pads140positioned between the teeth128of the inner shell120and the grooves136of the inertia ring130. Further, energy dissipation of the damping pads140and the o-ring144may be tuned, for example through selection of materials and/or selection of geometric fits between components, such that the total energy dissipation of the damper100may be achieved.

Relative rotation between the inertia ring130and the outer shell110may be resisted by the o-ring144. As the mechanical forces rotating the inertia ring130relative to the outer shell110overcome the gripping force applied by the o-ring144, the o-ring144tends to slip relative to at least one of the gland134or the can portion114. Slip between the o-ring144and the gland134and/or the can portion114may generate heat, thereby reducing the mechanical energy applied to the damper100. Therefore, the o-ring144may dissipate mechanical energy introduced to the damper100, and prevent that mechanical energy from being reintroduced to the crankshaft of the reciprocating engine and inducing vibrations to the crankshaft assembly.

Referring now toFIGS. 8-10, various embodiments of inertia rings230,330,430are depicted. Referring toFIG. 8, one embodiment of the inertia ring230may include a plurality of local ballast members232that are coupled to the inertial portion138of the inertia ring230. In some embodiments, the density of the ballast members232may be greater than the density of the inertial portion138of the inertia ring230, such that the mass and the polar moment of inertia of the inertia ring230is increased by inclusion of the ballast members232. In other embodiments, the density of the ballast members232may be less than the density of the inertial portion138of the inertia ring230, such that the mass and the polar moment of inertia of the inertia ring230is reduced by inclusion of the ballast members232. Modifying the mass and the polar moment of inertia of the inertia ring230may modify the fundamental and/or harmonic vibratory frequencies of the crankshaft assembly.

In some embodiments, the ballast members232may include a threaded engagement that interfaces with the inertial portion138of the inertia ring130. In other embodiments, the ballast members232may be adhered to the inertial portion138of the inertia ring. In yet other embodiments, the ballast members232may be coupled to the inertia ring through a welded or brazed interface.

Referring toFIG. 9, in some embodiments, the inertia ring330may include a bulk ballast member332coupled to the inertial portion138of the inertia ring330. In this embodiment, the bulk ballast member332is an annular-shaped member that provides a majority of the polar moment of inertia of the inertia ring330. In some embodiments, the density of the bulk ballast member332may be greater than the density of the inertial portion138of the inertia ring330, such that the mass and the polar moment of inertia of the inertia ring330is increased by inclusion of the bulk ballast member332. In other embodiments, the density of the bulk ballast member332may be less than the density of the inertial portion138of the inertia ring330, such that the mass and the polar moment of inertia of the inertia ring330is reduced by inclusion of the bulk ballast member332. In some embodiments, the bulk ballast member332may be coupled to the inertia ring330through an interference fit of adjacent diameters.

Referring now toFIG. 10, in another embodiment, the inertia ring430may include a balance member432. The balance member432may be positioned proximate to the inertial portion138of the inertia ring430. Portions of the balance member432may be selectively removed through a variety of material removal operations such that the balance of the inertia ring430may be neutralized. Tolerances associated with manufacturing the inertia ring430, in particular tolerances associated with manufacturing operations that form the grooves136and the groove valleys139, may tend to shift the balance of the inertia ring430away from a neutral axis. By removing portions of the balance member432, neutral balance of the inertia ring430may be restored, such that rotation of the inertia ring430does not induce imbalance into the crankshaft of the reciprocating engine.

It should now be understood that dampers according to the present disclosure add mass to a crankshaft assembly of a reciprocating engine, which may modify the fundamental and harmonic vibratory frequencies of the crankshaft. Modification of the fundamental and harmonic vibratory frequencies may avoid a high-frequency interaction of the crankshaft within the engine operating speed range, which may increase crankshaft life. Further, the dampers include an inertia ring that is constrained from moving in the axial direction and the radial direction relative to the crankshaft, and allowed to rotate in the circumferential direction relative to the crankshaft by compressing a plurality of damping pads. The damper absorbs mechanical vibrations imparted to the crankshaft and dissipates the energy associated with the mechanical vibrations. The damping pads distribute the load across all of the intermeshed teeth and grooves of the damper to minimize wear to the damping pads, thereby increasing damper usable life.