Crankshaft decoupler

[0001] The present invention relates to a crankshaft and a motor vehicle drive assembly, and more specifically to a decoupling unit that enables overdrive of a drive unit, i.e. temporary operation at a speed other than the speed of the crankshaft, and decoupling, i.e. mechanical separation of the drive assembly from the crankshaft and reduction between torsional vibrations.

Description of the technique related to the invention [0002] In automotive engines, it is commonly used to transfer a portion of the engine power to a number of belt-driven accessory devices, using a serpentine closed belt. Typically, any such belt-driven accessory includes a pulley coupled to the belt and the belt is driven by a drive pulley coupled directly to the crankshaft.

[0003] Internal combustion engines operate as impulse systems, continually accelerating and decelerating, causing engine vibration. As a result of such variable speed of operation, belt-driven auxiliary devices, driven via a crankshaft, accelerate and slow down constantly. This can cause unacceptable noise and vibration levels, as well as reduce the strength of additional devices due to the highly pulsating load and vibration. In addition, rapid engine slowdowns and accelerations occur, for example, when shifting gears and when starting and stopping the engine, cause the drive belt to squeal, caused by belt slip on the pulley, as well as a high impact load on the belt.

[0004] A known solution is to install a decoupler assembly between the belt-driven accessory and the pulley to allow the belt-driven accessory to temporarily operate at a higher speed, i.e., over-speed of the pulley when the pulley oscillates due to the speed of the motor. An example of such a decoupler is disclosed in US Patent No. 6,083,030, issued to Mevissen and others on July 4, 2000. Further examples of such decouplers are disclosed in US Patent No. 6,394,248 to US Patent No. 5,139,463, which is the disclosure of the preamble of claim 1. 1, and in US Patent No. 5,139,463, issued to Bytzek and others on August 18, 1992.

[0005] Cases of decoupling assembly between the belt drive device and the pulley are also known to suppress vibrations between them and to enable operation at a higher speed and thereby reduce noise and shock loads. An example of such a decoupler is disclosed in US Patent No. 6,044,943, issued to Bytzek and others on April 4, 2000.

[0006] Nevertheless, it remains desirable to provide a decoupler assembly that is strong enough to withstand frictional loads, to allow the crankshaft drive pulley to temporarily operate at a higher speed, i.e., the crankshaft overdrive, when the engine speed increases and decreases, and decouples, or would separate the torsional vibrations of the drive pulley when the crankshaft oscillates during normal operation.

Summary of the Invention [0007] According to the present invention, a decoupler assembly according to claim 1 has been developed.

Short description of the drawings

[0008] The advantages of the present invention will be readily appreciated when it is better understood by reading the following detailed description considered together with the accompanying drawings, of which:

Figure 1 is a front view of a motor vehicle of a decoupling assembly according to one aspect of the present invention;

Figure 2 is an exploded perspective view of the decoupler assembly.

Figure 3 is an exploded perspective view of the drive hub and the decoupler assembly bearing assembly;

Figure 4 is an exploded perspective view of the drive hub coupled between the upper and lower spring cases and the decoupler assembly coupling element;

Figure 5 shows a top view of the lower spring shell, biasing members and coupling element.

Figure 6 shows a top view of the lower spring cover.

Figure 7 shows a cross-sectional view of the same along line 7-7 in figure 6.

Figure 8 shows a top view of the upper spring cover, biasing members and coupling element;

Figure 9 is an exploded perspective view of a decoupler assembly with a torsional vibration damper;

Figure 10 shows a top view of the decoupler assembly during its acceleration to drive the drive pulley in a momentary manner; and

Figure 11 shows a top view of the decoupler assembly during its release to allow the drive pulley to exceed the speed of the drive hub.

Detailed Description of the Preferred Embodiment [0009] Referring to figure 1, the internal combustion engine for a motor vehicle is indicated in its entirety by 10. The engine 10 includes several additional belt-driven devices 12, such as an alternator, compressor, etc. For each additional device 12 with belt drive, pulley 14 is actively engaged to drive devices 12 by turning the pulley 14. The engine 10 also includes a crankshaft 16, which essentially provides output mechanical torque resulting from the operation of the engine 10. A serpentine closed belt 18 is mounted around each belt pulley 14 of belt-driven auxiliary devices 12 18. The belt 18 is driven in a direction driven by the crankshaft rotation 16, which causes the pulleys to rotate 14. The crankshaft torque modulator, i.e. the decoupler assembly 20, is actively coupled between crankshaft 16 and belt 18.

[0010] Referring to figure 2, the decoupler assembly 20, which is shown in an exploded view, includes a drive pulley 22 with an annular outer race 24 that is formed between a pair of spaced apart, convex and parallel rims 25 and in which a belt 18 is mounted The drive pulley 22 also includes an annular inner surface 26 of the clutch that is anti-static and substantially concentric with the outer race 24. The drive pulley 22 further includes a disk 28 that extends between the outer race 24 and the inner surface 26 of the clutch.

ΕΡ2 273 144 BI

A hollow cylindrical hub 30 projects axially from the center of the disk 28, which is concentric with the internal surface 26 of the clutch to form the bearing surface 32 of the hub.

[0011] Referring to Figures 2-4, the decoupler assembly 20 further includes a drive hub 40, preferably made of metal, permanently attached to the crankshaft 16 by any suitable fastener or connecting means allowing it to pivot with it. The drive hub 40 includes a generally flared cylindrical main body 42 which defines an inner surface 44 and has a circumferential radial rim 45. From the center of the main body 42 extends axially to the distal end the support post 46. From the radial rim 45 of the main body 42 extends radially outward at least one, and preferably a plurality of tongues 48, 50. Each of the tongues 48, 50 has a leading edge 52 extending substantially perpendicular from the main body 42 and the rear edge 54 protruding angularly from the main body 42.

[0012] The bearing assembly 60 pivotally couples the drive pulley 22 to the drive hub 40. The bearing assembly 60 includes a round inner ring 62 surrounded by a round outer ring 64. A plurality of rolling elements 66 are provided between the inner ring 62 and the outer ring 64. The inner ring 62 is mounted around the periphery of the support hub 46 of the drive hub 40, and the outer ring 64 is fitted by forcing into the bearing surface 32 of the drive pulley 22 to provide a rotatable connection between these elements. In a preferred embodiment, the inner ring 62 projects axially out of the outer ring 64 to form a projection for receiving disk-shaped gasket 68 therein to seal the rolling elements 66 between the inner rings 62 and the outer 64 and to seal oil or grease inside bearing assembly 60 and drive pulley 22, as will be described in more detail below. However, the inner ring 62 may lie axially in the same plane as the end of the outer ring 64. In this case, the seal 68 may be seated around the periphery of the extended flange portion of the support post 46 so that it adheres sealingly to the ends of both the inner ring 62 and outer ring 64. Gasket 68 may be a separate or integral part of bearing assembly 60. Alternatively, a bushing may be used instead of bearing assembly 60. Basically, the bushing provides better damping than the 60 bearing assembly.

[0013] Referring to Figures 2 and 4-7, the decoupler assembly 20 further includes a lower spring cover 70 and an upper spring cover 100 that are actively coupled to the drive hub 40. Both shields, 70 and 100, are preferably formed from organic plastic. The lower spring cover 70 is substantially disk-shaped and extends between cylindrical and substantially concentric inner surfaces 72 and outer 74. From at least those portions of the outer surface 74 that form the ledge or projection, and from the outer peripheral support surface 77, a radial shoulder member 75 extends radially for supporting and engaging the thorns with the inner surface 26 of the pulley drive coupling 22. As shown in the preferred embodiment the radial collar 75 extends only along a portion of the periphery of the outer surface to reduce the weight of the lower spring cover 70. It should be noted, however, that the ring member 75 may be a continuous circumferential ring that extends over the entire perimeter of the outer surface 74. In addition, the axial thickness of the radial ring 75 increases gradually and continuously at the perimeter of the outer surface 74 so as to form a helical, i.e. raised, contour. supporting surface 79. In the lower shell 70 springs,

ΕΡ 2 273 144 BI between the inner surfaces 72 and the outer 74, at least one, but preferably a plurality of furrows 76 is formed and carved. Each of the furrows 76 extends in an arc between the first end 78 and the second end 80. The furrows 76 are flush end to end and are arranged substantially in a circle along the circumference of the lower spring shell 70. A diagonal retaining gap 82 extends between adjacent furrow ends 76, extending from the outer surface 74 to the substantially rectangular cavity 84. L or U-shaped locking tab embedded in the cavity 84, i.e. the clutch stop 85 preferably made of extruded metal. In the outer surface 74, numerous notches 86 are made to reduce the weight of the spring cover 70 and to form a series of alternating corrugations 88, 90 in the outer surface 74. In addition, lubricant to lubricate the inner surface 26 of the drive clutch can be transferred in the notches 86 pulley 22. Each of the corrugations 88 passes an opening 92 for receiving a fastener 94, such as a rivet or a screw, to secure the lower spring cover 70 permanently to the upper spring cover 100. In each of the corrugations 90, an elongated slot 96 is provided for reconciling the position and connecting the upper spring cover 100, as will be described in more detail below. In addition, the lower spring cover 70 includes a counterweight in the form of an enlarged biocide 98 formed between the inner surfaces 72 and the outer 74 which is radially opposite the holding gap 82 and the cavity 84 to rotate the lower spring cover 70.

[0014] Referring to Figures 2, 4 and 8, the upper spring shell 100 also has a substantially disk shape and extends between cylindrical and substantially concentric inner surfaces 102 and inner 104. In the upper spring shell 100, between inner surfaces 102 and outer 104, at least one, but preferably numerous furrows 106 are formed and grooved. Each of the furrows 106 extends in an arc between the first end 108 and the second end 110. Furrows 106 are leveled end-to-end and are arranged substantially in a circle along the circumference of the upper spring cover 100. An oblique convex locking wall 112, 114 extending from the outer surface 104 to the other end 110 of each furrow 106 extends between each pair of adjacent furrow ends 106 to abut against the rear edge 54 of each of the respective tabs 48, 50 of the drive hub 40. In addition, one of the locking walls 112, 114 is positioned to cover the clutch stop 85 to retain the stop 85 in the cavity 84 of the other spring cover 70. The upper spring cover 100 further includes an axially extending alignment tab 115 that extends diagonally between the inner surfaces 102 and the outer surfaces 104. The alignment tab 115 is sized to be received in the holding gap 82 to guarantee the correct orientation between the lower 70 and upper spring shell 100. A plurality of cutouts 116 are made in the outer surface 104 to reduce the weight of the upper spring shell 100 and to form in outer surface 104 of a series of alternating corrugations 118, 120. In addition, a lubricant may be conveyed in the notches 116 to lubricate the inner surface 26 of the pulley drive clutch 22. Through each of the corrugations 118, an opening 122 passes coaxially with the corresponding hole 92 in the inferior sheath 70 for receiving the fastener 94 in to secure the lower spring cover 70 permanently to the upper spring cover 100. In each of the corrugations 120, an axially protruding and slightly tapered tab 124 is formed to reconcile the axial position with the corresponding longitudinal slot 96 in the lower spring cover 70 and to provide a rigid connection for

Przenoszenia2 273 144 BI for torque transmission between the lower spring cover 70 and the upper spring cover 100. In addition, the upper spring cover 100 includes a counterweight in the form of an enlarged side 126 formed between the inner surfaces 102 and outer 104, which is radially opposite the holding gap 82 and the cavity 84 in the lower spring cover 70 to pivotally balance the lower 70 and upper spring cover 100.

[0015] The decoupler assembly 20 also includes a plurality of biasing members 130 in the form of helical coil springs. In each of the radially and axially aligned furrows 76; 106, a biasing member 130 is maintained between the lower spring cover 70 and the upper spring cover 100. Each of the biasing members 130 extends in an arc between the first 132 and second ends of the springs 134. About half of the first 132 and second ends of the springs 134 rests against the first 78 and second ends 80 of furrows 76 in the lower spring cover 70 and the second half rests on the first 108 and second ends of 110 furrows 106 made in the upper spring cover 100. After the axial and radial alignment of the lower 70 and upper spring covers 100 and pressing them together, the biasing members 130 are embedded in respective furrows 76, 106 between the lower 70 and upper spring covers 100. The biasing members 130 may be made to have an arcuate shape corresponding to the arcuate shape of the furrows 76, 106, or may be straight, and only then bent into the appropriate shape when depositing in the furrows 76, 106. It should also be noted that the biasing members 130 may include any compressible or resilient member embedded in the furrows 76, 106, such as a member being a kind of a rubber spacer or compressible fluid. Preferably, a lubricant, such as oil or grease, is provided in the furrows 76, 106 to reduce friction between the biasing members 130 and the spring covers 70, 100. In general, the lubricant also improves the damping characteristics of the decoupler assembly 20. The damping characteristics can be adapted to the specific application. This means that the damping characteristics can be reduced or increased, depending on the type of lubricant placed in the furrows 76, 106 and the decoupler assembly 20.

[0016] The coupling element 140 is located adjacent the inner surface 26 of the pulley driving clutch 22. More specifically, the coupling element 140 is a coil spring with a plurality of arms 142 extending helically between proximal end 144 and distal end 146. Proximal end 144 of the coupling element 140 is held stationary in the holding gap 82 made in the lower spring cover 70. The tip of the proximal end 144 of the coupling element 140 enters the cavity 84 and abuts the clutch stop 85. The coupling element 140 is supported by a radial ring member 75 such that a raised p rim member support surface 79 of the rim member 75 suitably complements the contour of the helical turns 142. The turns 142 are thorns coupled from the outside to the internal surface 26 of the clutch such that the rotational acceleration of the drive hub 40 relative to the drive pulley 22 in the driven direction of the crankshaft 16 causes the turns 142 to expand radially outward to engage the drive hub 40 with the drive wheel pulley 22. Coils 142 grip the internal surface 26 of the clutch so that the drive pulley 22 rotates together with the drive hub 40. By contrast, releasing the drive hub 40 relative to the drive pulley 22 causes the turns 142 to shrink radially inward. The turns 142 release the clutch internal surface holder 26 to allow the drive wheel to rotate

ΕΡ 2 273 144 BI belt 22 at a speed greater than the speed of the drive hub 40. Preferably, turns 72 have a rectangular cross-section.

[0017] Referring again to Figure 2, the decoupler assembly 20 is attached by seating the biasing members 130 in the furrows 76 of the lower spring cover 70. The clutch stop 85 is located in the cavity 84. The coupling member 140 is located on the periphery of the lower spring cover 70, and the proximal end 144 is located in the retaining slot 82, and its tip rests against the clutch stop 85. The coupling element 140 is supported by a radial rim member 75 such that the helical coils 142 complement the contour of the raised support surface 79 formed by the rim member 75. The drive hub 40 is then positioned in the center of the lower spring cover 70 so that the radial rim 45 is seated on the periphery of the inner surface 72 and the tabs 48, 50 are placed between adjacent furrow ends 76. Then, the upper spring cover 100 is aligned axially and radially with the lower spring cover 70 so that the biasing members 130 are seated in the furrows 106 and the tongues 48, 50 are similarly placed between adjacent furrow ends 106. The alignment tab 115 is positioned to be received in the holding gap 82 to guarantee the correct orientation between the lower spring covers 70 and the upper 100 and to place blocks 98, 126 that counterbalance the proximal end 144 of the coupling element 140. The counterbalance block 126 should be 180 degrees opposite the proximal end 144 of the coupling element 140. The alignment tab 115 further contacts the proximal end 144 of the coupling element 140 and presses it to hold the end 144 in the holding gap 82. The upper spring cover 100 is similarly embedded within the periphery of the coupling element 140. The axially protruding and tapering tongues 124 are received in the respective slots 96 in the lower spring cover 70 to provide a rigid connection and transfer of torque between the covers 70, 100. The upper and lower spring covers 100 and 70 are permanently joined by inserting attachment elements 94 into each of the coaxially arranged holes 92, 122.

[0018] The bearing assembly 60 is press fit into the bearing surface 32 of the drive pulley hub 22, and the seal 68 is pressed onto the inner ring 62 so that it surrounds it, and pressed against a projection formed with the outer ring 64 to seal the bearing assembly 60 and driving pulley 22.

[0019] The drive hub 40, lower and upper spring covers 100 and coupling element 140 are then positioned in the area inside the annular inner surface 26 of the clutch so that the support hub 46 of the drive hub 40 passes through the inner ring 62 of the bearing assembly 60 for rotationally engagement. drive hubs 40 with a drive pulley 22. The coupling element 140 is then partially frictionally coupled to the inner surface 26 of the clutch, and the outer bearing surface 77 of the radial flange 75 is frictionally coupled to the inner surface 26 of the drive pulley clutch 22 and supports it.

[0020] The internal cavity of the drive pulley 22 is filled with a lubricant such as oil or grease, which is desirable to reduce friction between components and provide damping. The disk-shaped cover 150 closes the drive pulley 22 and covers the upper cover 100 of the springs. Preferably, the cover 150 includes an inner seal 152 for contact

Uszczelni 2 273 144 BI sealing with the main body 42 of the drive hub 40 and the outer peripheral seal 154 for sealing the driving pulley 22, which seals together ensure the fluid tightness of the decoupler assembly 20. Cover 150 can be permanently attached to the driving wheel pulley 22 by rotating the periphery of the protruding rim 156 on the drive pulley 22 to the outer peripheral surface of the cover 150.

[0021] Referring to Figure 9, a torsional vibration damper 160 may be permanently attached to the hub 40, as is known to those skilled in the art, to damp vibrations occurring on the crankshaft 16 during engine operation 10. A torsional vibration damper 160 the embodiment shown in figure 9 includes a hub 162 for mounting a muffler mounted to a drive hub 40. An elastomer ring is attached to the muffler mounting hub 162 by inertia ring 166 to complete the assembly.

[0022] Referring to Figures 2 and 10, during operation, the engine 10 accelerates or slows down the rotational movement of the crankshaft 16 and drive hub 40 in the driven direction V relative to the drive pulley 22, First, during normal acceleration, the tongues 48, 50 enter into contact with the first ends 132 of the biasing members 130. Initially, the first ends 132 of the springs are pivoted relative to the respective second ends 134 of the springs when the biasing members 130 are pressed against the second ends 80, 110 of the furrows 76, 106. The degree of displacement of the second ends 134 of the springs during acceleration is directly proportional to the acceleration of the drive hub 40 and the stiffness of the biasing members 130. Finally, the upper 100 and lower spring covers 70, pushed by the compressed biasing members 130, begin to accelerate together with the drive hub 40. This means that the transfer of torque or acceleration from the drive hub 40 to the upper 100 and lower spring covers 70 is somewhat delayed when the biasing members 130 are compressed. The acceleration of the lower 70 and upper spring covers 100 relative to the drive pulley 22 causes the turns 142 to extend radially outward toward the interior surface 26 of the clutch. More specifically, the rotational movement of the other spring cover 70 presses the locking tab 85 to the proximal end 144 of the coupling element 140 so as to radially expand the turns 142 to contact the internal surface 26 of the clutch. The outline of the retaining gap 82 in the lower spring cover 70 supports the proximal end 144 of the coupling element 140 to prevent localized bending of the turns 142 and to force uniform radial expansion over the entire length of the helical turns 142, aiming to bring them into contact with the internal surface 26 of the clutch. The turns 142 grip the clutch surface 26 with a sufficient friction force for the drive pulley 22 to rotate together with the drive hub 40, driving the belt 18. [0023] Referring to figures 2 and 11, while rapidly reducing the rotational speed of the crankshaft 16 and the drive hub 40, which may be due to gear shifting, starting and stopping the engine, etc., it is desirable to selectively allow the drive pulley 22 to rotate with greater speed than the drive hub 40, i.e. exceeding the speed of the drive hub 40 and crankshaft 16 to prevent belt slipping on the drive pulley 22, which would make a belt squeak or noise. During such deceleration, the tongues 48, 50 brake to reduce the load or torque exerted on the first ends 132 of the biasing members 130. The biasing members 130 may stretch or bounce back to the tongues 48, 50, thereby also reducing the torque exerted on the lower 70 and upper spring cover 100. Rear edges 54

482 273 144 BI of tongues 48, 50 come into contact with the respective locking walls 112, 114 on the upper cover of 100 springs to maintain acceleration of covers 70, 100 springs on an equal footing with hub acceleration 40. Release of spring covers 70, 100 relative to the drive pulley 22 causes the turns 142 to shrink radially inward relative to the inner surface 26 of the clutch. The shrinkage of the turns 142 allows the internal surface 26 of the clutch to run out relative to the clutch mechanism 140, thereby enabling the drive pulley 22 to operate at a speed (V) greater than the drive hub 40 and crankshaft 16 (V-ó), i.e. exceeding the speed of the crankshaft 16, and preventing belt slippage on the drive pulley 22 and avoiding assembly noise.

[0024] Furthermore, during normal acceleration and deceleration of the crankshaft 16, as a result of the combustion process taking place in the engine, higher frequency torsional oscillations and high impact loads occur in the crankshaft 16. The decoupler assembly 20 further decouples, dampens and mechanically separates these torsional vibrations between the crankshaft 16 and the drive pulley 22. Specifically, the oscillating torsional vibrations of the crankshaft 16 are damped or separated from the drive pulley 22 by the biasing members 130. The oscillations of the crankshaft 16 and thus the drive hub 40 act on the first ends 132 of the biasing members 130 so that they bias the biasing members 130 to the other 80, 110 furrows 76, 106. The biasing members 130, i.e., arcuate helical springs, constantly compress and expand due to the torsional vibrations of the drive hub to damp, separate and absorb vibration caused by torsional vibration. The biasing members 130 thus reduce the shock loads generated by the engine, which would normally be transferred by the crankshaft 16 to the drive pulley 22, and thus directly to the belt-driven auxiliary devices. In other words, the biasing members 130 reduce the acceleration and deceleration values ​​and introduce a phase shift between the input force applied by the drive hub 40 and the output reaction on the drive pulley 22. This phase shift is manifested by a reduction in system resonance. Lowering the powertrain resonance suppresses unwanted vibrations and eliminates or prevents the occurrence of torsional displacement caused by resonance of the system.

Thus, the decoupler assembly 20 allows the temporary operation of the auxiliary devices 12 with belt drive at a higher speed, i.e. exceeding the speed of the crankshaft 16, when the rotational speed of the crankshaft 16 changes due to the oscillation of the speed of the engine 10, which results in smoother engine operation, lower noise level and longer belt life. The decoupler assembly 20 further dampens or separates the torsional vibrations occurring between the crankshaft 16 and the belt 18 when the engine 10 is running.

[0026] Although the decoupler assembly 20 is described above as part of the internal combustion engine, it should be noted that the decoupler assembly 20 can be used in any rotary or belt drive system, such as a generator or belt conveyor system, or in any rigid shaft system with couplings pulley or misaligned, in which the hub is not necessarily loaded.

[0027] It should also be noted that the drive pulley 22 can be adapted to receive any type of drive element, such as a rubber or plastic multi-ribbed belt, V-belt or synchronous belt. The drive pulley 22 may also be adapted to receive other drive components, such as the flat steel belt it uses

For example, in a variable continuously variable transmission or in a multi-component chain made of plastic or steel.

[0028] The present invention has been described illustratively and it should be understood that the terminology used in the description is descriptive rather than limiting. In the light of the above statements, many modifications and variations of the present invention are possible. It is therefore to be understood that, within the scope of the appended claims, the present invention may be implemented in a manner other than described in detail.