Crankshaft dampers for internal combustion engines

Abstract

An engine assembly has a vibration damper rotatably coupled to a crankshaft. The vibration damper has a first spoke and a second spoke connecting a hub to an inertial counterweight, wherein the inertial counterweight circumferentially surrounds the hub and is spaced apart from the hub. Each of the spokes has an airfoil portion. The first spoke is oriented at a positive angle of attack and the second spoke is oriented at one of a negative angle of attack and a zero angle of attack. The crankshaft vibration damper is provided by a member having a first spoke and a second spoke, the first spoke and the second spoke extending radially outward from the hub to an outer rim supporting the inertial counterweight. A chord associated with the first spoke is oriented at a first angle of attack relative to a plane of rotation of the member. A chord associated with the second spoke is oriented at a second angle of attack relative to the plane of rotation.

Description

Technical Field

[0001] Various embodiments are directed to a crankshaft damper for an internal combustion engine. Background Art

[0002] Internal combustion engines may be provided with crankshaft dampers to reduce crankshaft torsional accelerations and prevent corresponding durability and noise, vibration and harshness (NVH) issues. During operation, crankshaft dampers may contribute to or cause an increase in overall engine noise. Summary of the invention

[0003] In one embodiment, an engine assembly is provided with a crankshaft and a vibration damper rotatably coupled to the crankshaft. The vibration damper has a first spoke and a second spoke connecting a hub to an inertial counterweight, wherein the inertial counterweight circumferentially surrounds the hub and is spaced apart from the hub. Each of the spokes has an airfoil portion. The first spoke is oriented at a positive angle of attack and the second spoke is oriented at one of a negative angle of attack and a zero angle of attack.

[0004] In another embodiment, a crankshaft damper is provided by a member having a series of spokes extending radially outward from a hub to an outer rim, wherein the outer rim circumferentially surrounds the hub and is spaced from the hub to support an inertial counterweight. Each of the spokes has a chord extending between a leading edge and a trailing edge. A chord associated with a first spoke in the series of spokes is oriented at a first angle of attack relative to a plane of rotation of the member. A chord associated with a second spoke in the series of spokes is oriented at a second angle of attack relative to a plane of rotation of the member.

[0005] In yet another embodiment, a crankshaft damper is provided with a member having a first spoke and a second spoke connecting a rim to a hub, wherein the rim circumferentially surrounds the hub and is spaced apart from the hub. Each of the spokes has an elongated cross-section, wherein the first spoke is oriented at a positive angle of attack and the second spoke is oriented at one of a negative angle of attack and a zero angle of attack. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 shows a schematic diagram of an internal combustion engine configured to implement various embodiments according to the present disclosure;

[0007] Figure 2 An engine assembly including an engine cover is shown, and Figure 1 A partial perspective view of the crankshaft and crankshaft damper of an engine.

[0008] Figure 3 A perspective view showing a crankshaft damper according to one embodiment;

[0009] Figure 4 Show Figure 3 A cross-sectional view of a crankshaft damper;

[0010] Figure 5 Show Figure 3 Another cross-sectional view of the crankshaft damper;

[0011] Figure 6 Show Figure 3 Yet another cross-sectional view of a crankshaft damper;

[0012] Figure 7 Compared with conventional crankshaft dampers, Figure 3 The curve of sound pressure level and frequency of the crankshaft vibration damper;

[0013] Figure 8 A perspective view showing a crankshaft damper according to another embodiment;

[0014] Fig. 9 a perspective view showing a crankshaft damper according to yet another embodiment; and

[0015] Fig.10 A perspective view of a crankshaft damper according to another embodiment is shown. DETAILED DESCRIPTION

[0016] As required, detailed embodiments of the present disclosure are provided herein; however, it should be understood that the disclosed embodiments are merely exemplary and may be embodied in various forms and alternative forms. The drawings are not necessarily drawn to scale; some features may be enlarged or minimized to show 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 different ways.

[0017] Figure 1 A schematic diagram of an internal combustion engine assembly 20 configured to implement various embodiments according to the present disclosure is shown. In some embodiments, the engine 20 is used as the sole prime mover in a vehicle, such as a conventional vehicle or a stop-start vehicle. In other embodiments, the engine may be used in a hybrid vehicle, in which an additional prime mover, such as an electric motor, may be used to provide additional power to propel the vehicle.

[0018] 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 located in each cylinder and is connected to a crankshaft 26 via a connecting rod 28.

[0019] 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 valves 30 and exhaust valves 34 may be operated in various ways known in the art to control engine operation. The engine 20 is shown with intake valves 30 and exhaust valves 34, each with an associated camshaft 38, 40, respectively, in a direct 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 camshaft actuation, an overhead valve configuration in which the valves are operated by push rods or rockers, etc. The camshafts 38, 40 may be rotationally connected to and driven by the crankshaft 26, and in one embodiment driven by a gear train according to the present disclosure as described below.

[0020] Each cylinder 22 can be operated under a four-stroke cycle, which includes an intake stroke, a compression stroke, an ignition stroke, and an exhaust stroke. In other embodiments, the engine can be operated in 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).

[0021] 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.

[0022] During the compression stroke, the intake valve 30 and the exhaust valve 34 are closed. The piston 24 moves from the bottom to the top of the cylinder 22 to compress the air within the combustion chamber.

[0023] The fuel is then introduced into the combustion chamber and ignited. The engine may be configured as a spark ignition engine or a compression ignition engine, such as a diesel engine. During the expansion stroke, the ignited fuel-air mixture in the combustion chamber expands, thereby 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 in the crankshaft 26 and provides a mechanical torque output from the engine 20.

[0024] During the exhaust stroke, intake valve 30 remains closed and exhaust valve 34 opens. Piston 24 moves from the bottom of the cylinder to the top of cylinder 22 to remove exhaust gas and combustion products from the combustion chamber by reducing the chamber volume. Exhaust gas flows from combustion cylinder 22 to exhaust manifold 36.

[0025] 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 be varied for various engine strokes.

[0026] The crankshaft 26 may be provided with a crankshaft damper 42, for example to reduce crankshaft angle fluctuations generated by combustion and piston inertia torque. The crankshaft damper 42 may also be referred to as a harmonic damper or a torsional damper. The crankshaft damper 42 is connected for rotation with the crankshaft 26, for example at the free end or accessory drive end of the crankshaft. In one example, the damper 42 is interference fit to the crankshaft. The crankshaft damper 42 may additionally be provided as or used as an accessory drive pulley and may be provided with a gear transmission 44 with timing marks.

[0027] The cylinder block 50 and cylinder head 52 of the engine 20 may be at least partially enclosed in an engine cover, as described below. Figure 2 shown.

[0028] Figure 2 A partial perspective view of a crankshaft damper 42 mounted on a crankshaft 26 is shown, wherein the cylinder block 50 and the head 52 of the engine are enclosed within a cover 60. The cover 60 may include one or more cover elements that cooperate to enclose the engine. The cover 60 may be provided with a front cover 62. The front cover 62 is located on the accessory end of the crankshaft 26 or opposite to the flywheel mounting flange or the drive end of the crankshaft. The front cover 62 defines an aperture therethrough. The accessory end of the crankshaft passes through the aperture in the front cover so that the cover 62 is located between the damper 42 and the cylinder block 50 of the engine 20. Various sensors (such as a speed sensor 64 as shown) may be provided and mounted on the cover 60.

[0029] The crankshaft damper 42 is used to reduce crankshaft torsional acceleration and reduce or prevent corresponding durability and noise, vibration and harshness (NVH) issues. During operation, the rotation of the crankshaft damper may generate flow noise that radiates from the peripheral area of ​​the damper, which may contribute to the overall engine noise and may drive the overall engine noise to objectionable levels. Noise measurements were taken using acoustic holography, and the periphery of the damper showed increased noise radiation in this area.

[0030] The crankshaft damper 42 according to the present disclosure provides reduced noise during operation, thereby reducing overall engine noise.

[0031] During engine operation, the crankshaft damper 42 rotates with the crankshaft 26, and the rotational motion of the damper 42 causes adjacent air to move or induce air flow. A computational fluid dynamics analysis was performed on the crankshaft damper 42 as well as conventional crankshaft dampers.

[0032] Aeroacoustic analysis indicates that rotation of a conventional crankshaft damper causes air around the crankshaft damper (e.g., on the outside of the damper) to be drawn into the apertures or areas 70 between adjacent spokes and into the narrow gap 72 or spacing between the inner face of the crankshaft damper and the front cover 62. In one example, the narrow gap 72 has a size range of 2.5 mm to 10 mm. As the air flow between the inner face of the damper and the front cover 62 flows radially outward and passes over the peripheral edge 74 of the damper, it expands and causes the sound pressure level to increase and contributes to the increase in engine noise. Conventional crankshaft dampers or crankshaft dampers are arranged so that all spokes extend in or are defined by the plane of rotation of the damper. In conventional systems, attempts have been made to reduce noise by blocking the apertures (e.g., using foam blocks); however, this approach increases the complexity of manufacturing the plug and maintaining the plug during the life of the engine, increasing costs and other issues. Other conventional crankshaft dampers may be provided as a solid disc without orifices; however, while this reduces flow noise from the damper, such designs increase weight and result in additional noise due to vibrations transmitted from the crankshaft.

[0033] The damper 42 according to the present disclosure is designed to approach or provide neutral air flow or net zero air flow across the damper and through the apertures 70 between the spokes to reduce the amount of air flow through the gaps 72. Figure 2 The damper 42 is shown rotating in a counterclockwise direction about an axis of rotation 80 during operation of the engine 20 , wherein the axis of rotation 80 intersects and is perpendicular to the plane of rotation of the damper 42 .

[0034] Figures 3 to 6 According to one embodiment and for Figure 1 to Figure 2 An embodiment of the crankshaft damper 42 for use with the engine 20 and the assembly. For simplicity, Figures 3 to 6 The elements in the Figure 1 to Figure 2 Similar elements in the drawings are given the same reference numerals.

[0035] The crankshaft damper 42 is defined by a member 100. The member 100 has a hub 102. The hub 102 defines a central aperture 104 or hole 104 that is sized to receive a portion of the crankshaft 26.

[0036] The member 100 also has an outer rim 106. The outer rim 106 is provided by an annular shell and extends circumferentially around the hub 102. As shown, the outer rim 106 is spaced from the hub 102 and is concentric with the hub 102 about the axis of rotation 80.

[0037] The outer rim 106 supports an inertial counterweight 108, which also circumferentially surrounds the hub 102 and is spaced apart from the hub 102. The counterweight 108 may be connected to the outer rim 106 via an elastomeric element. In the example shown, the inertial counterweight 108 is symmetrical about the hub 102. In other examples, the counterweight may be provided as a counterweight element for a shock absorber. The outer peripheral edge 110 of the inertial counterweight provides the outer peripheral edge of the shock absorber and may be provided with a profile to act as a pulley or drive other components such as front end attachments.

[0038] The damper has a first inner face 112 directly adjacent the covers 60, 62 when installed in the engine assembly, and a second outer face 114 opposite the inner face.

[0039] The vibration damper 42 has a series of spokes 120 connecting the hub 102 to the outer rim 106 and the inertial weight 108. Figures 3 to 6 , the vibration damper 42 is shown as having three spokes 120, or a first spoke 122, a second spoke 124, and a third spoke 126. In other examples, the vibration damper can have other numbers of spokes 120, such as less than three spokes or more than three spokes. Each of the spokes 120 extends radially outward from the hub 102 toward the rim 106 and the counterweight 108 and defines the aperture 70 therebetween. As shown, the spokes 120 can be equally spaced from each other around the hub 102, or in other examples, the spokes 120 can be provided with variable spacing around the hub 102.

[0040] In various embodiments, the spokes 120 of the crankshaft damper 42 are provided with airfoil portions and a varying angle of attack to provide an aerodynamic shape so as to reduce the amount of air flow across the damper and through the narrow gap between the crankshaft damper and the engine front cover. The damper 42 not only reduces the amount of air flow through the gap 72 between the damper and the engine front cover, but also prevents an increase or decrease in the net air flow in front of the damper or on the side of the outer face 114 of the damper.

[0041] like Figures 4 to 6 As shown, each of the spokes 120 has an airfoil portion 128. The airfoil portions 128 of each of the spokes 120 may be the same as one another or may be different from one another. The airfoil portions 128 according to the present disclosure include conventional airfoil portions as well as flat plates. Each of the spokes 120 has an elongated cross-section that provides the airfoil portion 128 and extends from a leading edge 130 of each spoke 120 to a trailing edge 132. A chord 134 is defined for each spoke 120, wherein the chord 134 extends from the leading edge 130 to the trailing edge 132.

[0042] Each spoke 120 may have the same airfoil portion 128 along the length of the spoke 120 in the radial direction, or the airfoil portion 128 may vary in shape, size, or angle of attack along the length of the spoke such that the spoke has different airfoil sections at different radial locations along the spoke.

[0043] In the example shown, the crankshaft damper 42 has at least one spoke 122 oriented at a first, or positive, angle of attack 140 . Figure 4 A cross-sectional view of a first spoke 122 of the vibration damper 42 is shown with a positive angle of attack 140. The crankshaft vibration damper also has at least one spoke 124, 126 with a second angle of attack or a negative angle of attack or zero angle of attack. Figure 5 A cross-sectional view of a second spoke 124 of the vibration absorber is shown having a negative angle of attack 142 . Figure 6 A cross-sectional view of the third spoke 126 of the vibration absorber is shown with a zero angle of attack 144 such that the chord 134 is parallel or coplanar with the plane of rotation of the component 100. The angle of attack 140, 142, 144 of each spoke 120 is taken in the direction of movement of the spoke based on the direction of rotation of the vibration absorber 42 and is taken based on the chord 134 of the spoke and the plane of rotation of the vibration absorber 42.

[0044] Leading edges 130 of spokes 124 , 126 having negative or zero angles of attack 142 , 144 are positioned between the engine cover and leading edges 130 of spokes 122 having positive angles of attack 140 , or between the inner face 112 of the damper and leading edges 130 of spokes 122 having positive angles of attack 140 .

[0045] In one example, positive angle of attack 140 is within a range of 10-45 degrees and negative angle of attack 142 is within a range of 5-45 degrees or 10-45 degrees, although other ranges for each angle of attack are contemplated. Zero angle of attack 144 may be a zero value or may be substantially zero, such as within 5 degrees of zero.

[0046] The spokes 120 are used to deflect the air flow and control the air flow during the rotation of the crankshaft damper 42. The spokes 122 with a positive angle of attack 140 are used to draw the air flow toward the apertures 70 and gaps 72 and pump the air toward the cover. The spokes 124 with a negative angle of attack 142 draw the air flow away from the apertures 70 and gaps 72 by pumping the air away from the cover. The spokes 126 with a zero angle of attack 144 generally help to draw air toward the apertures 70 and gaps 72, but to a lesser extent than the positively oriented spokes.

[0047] The number of each of the positively angled spokes 122 and the negatively angled spokes 124 or zero angled spokes 126, as well as the angle of attack and shape and size of each of the spokes 120 can be selected and controlled to provide neutral or near-neutral air flow across the damper and reduce the overall noise of the damper and engine.

[0048] Figure 7 is a graph based on a computational model having sound pressure levels in decibels (dB) and pressure spectra in Hertz (Hz) at the inner periphery of the shock absorber 42 of an engine operating at 3000 rpm. Figure 3 The sound pressure level of the conventional damper is shown by line 152, where all spokes have zero angle of attack or are in the plane of rotation of the damper. The damper 42 according to the present disclosure provides a reduced sound pressure level at all times or provides broadband sound reduction. In addition, when integrated across the critical frequency range of noise or from 1000 Hz-2000 Hz, the damper 42 provides a significant 5 dB reduction over conventional dampers.

[0049] Figure 8 , Fig. 9 and Fig.10 Other embodiments of the crankshaft damper 42 according to the present disclosure are shown. For simplicity, Figures 8 to 10 The elements in the Figures 1 to 6 Similar elements in the drawings are given the same reference numerals.

[0050] Figure 8 A crankshaft damper 42 according to the present disclosure is shown having a first spoke configured as a positively oriented spoke 122 and oriented at a positive angle of attack 140, a second spoke configured as a positively oriented spoke 122 and oriented at a positive angle of attack 140, and a third spoke configured as a non-oriented spoke 126 and oriented at a zero or near zero angle of attack 144.

[0051] Fig. 9 A crankshaft damper according to the present disclosure is shown having a first spoke configured as a positively oriented spoke 122 and oriented at a positive angle of attack 140, a second spoke configured as a non-oriented spoke 126 and oriented at a zero or near zero angle of attack 144, and a third spoke configured as a non-oriented spoke 126 and oriented at a zero or near zero angle of attack 144.

[0052] Fig.10 A crankshaft vibration damper according to the present disclosure is shown, wherein the vibration damper has six spokes. Three of the spokes are arranged as positively oriented spokes 122 and oriented at a positive angle of attack 140, and the other three spokes are arranged as negatively oriented spokes 124 and oriented at a negative angle of attack 142. The positively oriented spokes and the negatively oriented spokes are arranged to alternate with each other around the vibration damper.

[0053] Various configurations and orientations of the spokes may be provided depending on the requirements and operating conditions of the engine 20. For example, the number of positively oriented spokes 122 or spokes having a positive angle of attack may vary, with each damper having at least one positively angled spoke.

[0054] The number of negatively oriented spokes 124 or spokes with negative angles of attack and non-oriented spokes 126 or spokes with zero or near zero angles of attack may also vary relative to one another, and for a vibration absorber having at least one negatively angled spoke 124 or non-oriented spoke 126. The positively oriented spokes 122 and the negatively oriented spokes 124 and / or non-oriented spokes 126 may be sequentially arranged in various orders relative to one another.

[0055] For multiple positively angled spokes 122, each may be disposed at a different positive angle of attack, or they may all be disposed at the same positive angle of attack, such as Fig.10 Similarly, for multiple spokes with negative angles, each spoke can be set at a different negative angle, or they can all be set at the same negative angle of attack, such as Fig.10 Each of the spokes may have the same airfoil portion, or shape, area and / or geometry, or may have a different airfoil portion or a different shape, area and / or geometry.

[0056] Although exemplary embodiments are described above, these embodiments are not intended to describe all possible forms of the present disclosure. Instead, the words used in the specification are descriptive rather than limiting, 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 various implemented embodiments may be combined to form additional embodiments of the present disclosure.

[0057] According to the present invention, an engine assembly is provided, having: a crankshaft; and a vibration damper, which is rotatably coupled to the crankshaft and has a first spoke and a second spoke connecting a hub to an inertial counterweight, the inertial counterweight circumferentially surrounding the hub and spaced apart from the hub, each of the spokes having an airfoil portion, the first spoke being oriented at a positive angle of attack and the second spoke being oriented at one of a negative angle of attack and a zero angle of attack.

[0058] According to one embodiment, the above invention is further characterized by an engine cover configured to at least partially surround an engine block, the crankshaft extending through the cover such that the cover is positioned between the block and the vibration damper.

[0059] According to one embodiment, the leading edge of the second spoke is positioned between the leading edge of the first spoke and the engine cover.

[0060] According to one embodiment, the first spoke and the second spoke are configured to control air flow across the damper to be neutral.

[0061] According to one embodiment, the second spoke is oriented at the negative angle of attack; and wherein the vibration absorber has a third spoke connecting the hub to the inertial counterweight, the third spoke having an airfoil portion and being oriented at zero angle of attack.

[0062] According to the present invention, a crankshaft damper is provided, comprising: a component having a series of spokes extending radially outward from a hub to an outer rim, the outer rim circumferentially surrounding the hub and spaced apart from the hub and supporting an inertial counterweight, each of the spokes having a chord extending between a leading edge and a trailing edge, the chord associated with a first spoke in the series of spokes being oriented at a first angle of attack relative to a plane of rotation of the component, and the chord associated with a second spoke in the series of spokes being oriented at a second angle of attack relative to the plane of rotation of the component.

[0063] According to one embodiment, the first angle of attack is a positive value; and wherein the second angle of attack is one of a negative value and zero.

[0064] According to one embodiment, the first angle of attack is a positive value; wherein the second angle of attack is a negative value; and wherein the chord associated with a third spoke in the series of spokes is oriented at a third angle of attack relative to a plane of rotation of the member, the third angle of attack being zero.

[0065] According to the present invention, a crankshaft damper is provided, which has: a component having a first spoke and a second spoke connecting a rim to a hub, the rim circumferentially surrounding the hub and being spaced apart from the hub, each of the spokes having an elongated cross-section, the first spoke being oriented at a positive angle of attack, and the second spoke being oriented at one of a negative angle of attack and a zero angle of attack.

[0066] According to one embodiment, each of said spokes has an elongated cross-section extending from a leading edge of said spoke to a trailing edge of said spoke, a chord being defined between said leading edge and said trailing edge.

[0067] According to one embodiment, the angle of attack of each spoke is taken between the plane of rotation of the member and the relative chord of the spoke.

[0068] According to one embodiment, the elongated cross-section of each of said spokes is formed as an airfoil portion.

[0069] According to one embodiment, the second spokes are oriented at the negative angle of attack; and wherein the member has a third spoke connecting the rim to the hub, the third spoke having an elongated cross-section and oriented at zero angle of attack.

[0070] According to one embodiment, the chord of the third spoke is parallel to the plane of rotation of the member, such that the third spoke is oriented at a zero angle of attack.

[0071] According to one embodiment, the first, second and third spokes are equally spaced from one another around the hub; and wherein each of the spokes extends radially outward from the hub to the rim.

[0072] According to one embodiment, the second spoke is oriented at the zero angle of attack; and wherein the member has a third spoke connecting the rim to the hub, the third spoke having an elongated cross-section and oriented at the zero angle of attack.

[0073] According to one embodiment, the hub defines a central aperture sized to receive an end of a crankshaft.

[0074] According to one embodiment, the positive angle of attack is relative to a plane of rotation and a direction of rotation of the component.

[0075] According to one embodiment, the positive angle of attack is within 5-45 degrees of the plane of rotation of the component; wherein the negative angle of attack is within 5-45 degrees of the plane of rotation; and wherein the zero angle of attack is within 5 degrees of the plane of rotation.

[0076] According to one embodiment, the rim supports an inertial weight.

Claims

1. An engine assembly, comprising: Crankshaft; as well as A vibration damper rotatably coupled to the crankshaft and having first and second spokes connecting a hub to an inertia counterweight circumferentially surrounding and spaced from the hub, each of the spokes having an airfoil portion, the first spoke being oriented at a positive angle of attack and the second spoke being oriented at one of a negative angle of attack and a zero angle of attack.

2. The engine assembly of claim 1, further comprising an engine cover configured to at least partially surround an engine cylinder block, the crankshaft extending through the cover such that the cover is positioned between the cylinder block and the vibration damper.

3. The engine assembly of claim 2, wherein the leading edge of the second spoke is positioned between the leading edge of the first spoke and the engine cover.

4. The engine assembly of claim 2, wherein the first spoke and the second spoke are configured to control air flow across the vibration damper to be neutral to reduce the amount of air flow flowing through the gap between the vibration damper and the engine cover, thereby reducing the overall noise of the vibration damper and the engine assembly.

5. The engine assembly of claim 1, wherein said second spoke is oriented at said negative angle of attack; and The vibration absorber has a third spoke connecting the hub to the inertial weight, the third spoke having an airfoil portion and oriented at a zero angle of attack.

6. A crankshaft damper, comprising: A member having first and second spokes connecting a rim to a hub, the rim circumferentially surrounding the hub and spaced apart from the hub, each of the spokes having an elongated cross-section, the first spokes being oriented at a positive angle of attack, and the second spokes being oriented at one of a negative angle of attack and a zero angle of attack.

7. The crankshaft damper of claim 6, wherein the positive angle of attack is within 5-45 degrees of the plane of rotation of the member; wherein the negative angle of attack is within 5-45 degrees of the rotation plane; and Wherein the zero angle of attack is within 5 degrees of the rotation plane.

8. The crankshaft damper of claim 6, wherein each of said spokes has an elongated cross-section extending from a leading edge of said spoke to a trailing edge of said spoke, a chord being defined between said leading edge and said trailing edge.

9. A crankshaft damper as claimed in claim 8, wherein the angle of attack of each spoke is taken between the plane of rotation of the member and the associated chord of the spoke.

10. The crankshaft damper of claim 6, wherein the elongated cross-section of each of the spokes is formed as an airfoil portion.

11. The crankshaft damper of claim 6, wherein said second spoke is oriented at said negative angle of attack; and The member has a third spoke connecting the rim to the hub, the third spoke having an elongated cross-section and oriented at a zero angle of attack.

12. The crankshaft damper of claim 11, wherein a chord of the third spoke is parallel to a plane of rotation of the member such that the third spoke is oriented at a zero angle of attack.

13. The crankshaft damper of claim 11, wherein the first spoke, the second spoke, and the third spoke are equally spaced from each other around the hub; and Each of the spokes extends radially outward from the hub to the rim.

14. The crankshaft damper of claim 6, wherein said second spoke is oriented at said zero angle of attack; and The member has a third spoke connecting the rim to the hub, the third spoke having an elongated cross-section and oriented at a zero angle of attack.

15. The crankshaft damper of claim 6, wherein the hub defines a central aperture sized to receive an end of a crankshaft; and The wheel rim supports an inertial counterweight.

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