FACE OF TENSIONER GUIDE OR ARM WITH PATTERN TO INFLUENCE CHAIN SYSTEM NVH PERFORMANCE

Abstract

A pattern for application to the face of the tensioner arm, guide or snubber in contact with a chain to intentionally break up the chain contact force between the back of the chain links and the tensioner arm, guide or snubber face. This is done to prevent alignment with the chain related orders which are causing NVH within the chain system or to increase overall NVH to obscure chain related orders.

Claims

1. A method of decreasing noise, vibration and harshness within a chain system comprising: determining chain related orders at which noise, vibration and harshness occurs within the chain system; determine which chain related orders to avoid increasing; creating a pattern for application to a face of a tensioner, guide or snubber comprising a plurality of grooves separated by spacers having a width, with the plurality of grooves and spacers at an angle relative to first and second edges of the face, wherein the pattern includes a pattern engagement dimension that does not equal a multiple of pitch and an integer or a multiple of pitch and 1 over an integer, such that the face of the tensioner, guide or snubber engages with a chain of the chain system of at least one chain order other than the chain related orders to avoid; and applying the pattern to the face of the tensioner, guide or snubber.

2. The method of claim 1, wherein the angle is 90 degrees.

3. The method of claim 1, wherein the angle not more than 90 degrees.

4. The method of claim 1, wherein the width of the spacers is constant within the pattern.

5. The method of claim 1, wherein the width of the spacers varies within the pattern.

6. The method of claim 1, wherein the grooves are radial across the face of the tensioner, guide or snubber.

7. The method of claim 1, wherein the grooves extend axially across the face of the tensioner, guide or snubber.

8. The method of claim 7, wherein the grooves each form an axial chain path.

9. A tensioner arm for tensioning a chain in a chain system to decrease noise, vibration and harshness within the chain system, the tensioner arm comprising: a mounting bracket mounted to the drivetrain transfer case encasing the chain system, the mounting bracket having a pivot axle extending perpendicular therefrom; an arm comprising a body having a first end, a second end, a first surface, and a second surface opposite the first surface, the second surface comprising, from the first end to the second end, a chain sliding surface, a non-engagement surface, and a boss portion defining a hole for rotatably receiving the pivot axle, the second surface further defined by a first edge and a second edge; a pattern applied to the chain sliding surface of the second surface, the pattern comprising: a plurality of grooves and spacers at an angle relative to the first edge and the second edge of the second surface of the body, wherein the pattern includes a pattern engagement dimension that does not equal a multiple of pitch and an integer or a multiple of pitch and 1 over an integer, such that the face of the tensioner, guide or snubber engages with a chain of the chain system at at least one chain order other than chain related orders to avoid; a torsion spring mounted between the mounting bracket and the boss portion, adjacent to the non-engagement surface, the torsion spring biasing the arm on the pivot axle towards a strand of the chain.

10. The tensioner arm of claim 9, wherein the grooves are axial and extend across the chain sliding surface from the first end towards the second end.

11. The tensioner arm of claim 10, wherein the grooves each form an axial chain path.

12. The tensioner arm of claim 9, wherein the angle is 90 degrees.

13. The tensioner arm of claim 9, wherein the angle is less than 90 degrees.

14. The tensioner arm of claim 9, wherein the width of the spacers is constant within the pattern.

15. The tensioner arm of claim 9, wherein the width of the spacers varies within the pattern.

16. The tensioner arm of claim 9, wherein a further comprising a shaft extending perpendicular from the mounting bracket, parallel to the pivot axle.

17. The tensioner arm of claim 16, wherein a first end of the torsion spring is mounted to the shaft and a second end of the torsion spring is mounted to the bracket.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 shows a schematic of a chain drive system interacting with a tensioning face surface of a tensioner arm, guide or snubber.

[0012] FIG. 2 shows a conventional tensioner arm for use with a chain drive system.

[0013] FIG. 3 shows an isometric view of a tensioner arm with a tensioning face with a pattern including straight grooves.

[0014] FIG. 4 shows a top view of the tensioner arm with a tensioning face with a pattern including straight grooves.

[0015] FIG. 5 shows an isometric view of a tensioner arm with a tensioning face with a pattern including diagonal grooves.

[0016] FIG. 6 shows a top view of the tensioner arm with a tensioning face with a pattern including diagonal grooves.

[0017] FIG. 7 shows a perspective view of a tensioner arm with different axial chain paths.

[0018] FIG. 8 shows a graph of half pitch frequency NVH metric of tensioner face geometry versus tensioner torque content.

[0019] FIG. 9 shows a graph of pitch frequency NVH metric of tensioner face geometry versus tensioner torque content.

[0020] FIG. 10 shows a graph of twice pitch frequency NVH metric of tensioner face geometry versus tensioner torque content.

[0021] FIG. 11 shows a perspective view of a tensioner arm with a pattern including variable spacing.

[0022] FIG. 12 shows a top view of the tensioner arm with a pattern including variable spacing.

[0023] FIG. 13 shows a top view of the tensioner arm with a pattern including variable spacing and diagonal grooves.

[0024] FIG. 14 is a flow diagram of a method of applying a unique pattern to a face of a tensioner arm, guide or snubber to alter the NVH.

DETAILED DESCRIPTION

[0025] FIGS. 3-4 show a tensioner arm 120 with a pattern including straight grooves 180. A tensioner arm 120 is present adjacent to one or both chain strands 8a, 8b. Each tensioner arm 120 has a bracket 162 which is connected to a drivetrain case (not shown) via bolt holes 163. Extending perpendicularly from the mounting bracket 162 is a shaft 165 and a pivot axle 164. The shaft 165 is parallel to the pivot axle 164. The pivot axle 164 receives an arm 168 formed of a body 178 having a first end 178a and a second end 178b, a first surface 188 and a second surface 183, opposite the first surface 181. The second surface 183 is defined by a first end 183a, a second end 183b, a first side 183c, a second side 183d and an arcuate boss portion 185. The second surface 183 includes, from a first end 178a to a second end 178b, a chain sliding surface 174, a non-engagement surface 174, and a boss portion 185. The chain sliding surface 174 has a unique pattern of grooves 180 and spacers 181 which engage with or interact with the backs 5 of the chain links 7 of each of the chain strands 8a, 8b. The pattern includes a plurality of radial grooves 180 separated by a spacer 181 of a width w. In this embodiment, the width w of the spacer 180 is constant through the pattern. The grooves 181 extend between the first and the second side 183c, 183d and are straight, such that the grooves 181 are at a right angle relative to the first side 183c or the second side 183d. The number of grooves 180, spacers 181 and width w of the spacers 181 can vary. The width w of the spacers 181 spacing the grooves 180 apart and the number of grooves 180 intentionally break up the chain contact force between the back 5 of the chain links 7 of the chain strand 8a, 8b and the chain sliding face 174 of the tensioner arm 168 to prevent alignment with the chain related orders which are causing NVH within the chain system.

[0026] The non-engagement portion 175 of the second surface 183 does not engage with the chain strands 8a, 8b and extends into the boss portion 185 which defines a hole 186 for rotatably receiving the pivot axle 164.

[0027] In alternate embodiments, the body 178 of the arm 168 can be manufactured from multiple pieces.

[0028] The unique pattern and associated groove pattern spacing is preferably calculated using equation 1.1 and 1.2 shown below. The pattern engagement dimension is the width of the spacers between grooves.

Pattern Engagement Dimension≠pn  (1.1)

Pattern Engagement Dimension≠p(1/n)(1.2)

Where:

[0029] p=Chain Pitch [0030] n=any integer

[0031] Equations 1.1 and 1.2 are removing the pitch orders which are causing NVH of the chain system due to engagement of each link 7, and engagement differences from the guide to the non-guide row or flank transitions of links 7 of the chain 8 of the chain system.

[0032] FIGS. 8-10 show examples of the tensioner face geometry including a smooth or continuous face 74 as in the prior art, an integer used with equations 1.1 and 1.2 to determine groove pattern spacing and a non-integer used to determine groove pattern spacing. For example, an integer of 2, results in

[00001]$p\left(\frac{1}{2}\right)$

or p(0.5). In other words, the spacing between the groove 180 is set as 0.5×pitch of the chain. As shown in the half pitch NVH metric shown in FIG. 8, the continuous face with no grooves results in a tensioner torque content of 0.15 Nm, whereas using 0.5×pitch (integer of 2) results in a tensioner torque content of 0.5 Nm, which results in an increase in NVH performance which causes more NVH within the chain system then using a continuous face. A non-integer of 2.5 results in

[00002]$\mathrm{Pattern}\mathrm{Engagement}\mathrm{Dimension}\ne p\left(\frac{1}{2.5}\right)$

or p(0.4). Using 0.4×pitch results in a tensioner torque content of 0.1 Nm, which is less NVH than the continuous face and 0.5×pitch.

[0033] FIG. 9 shows pitch frequency NVH metric. At 0.4×pitch (non-integer of 2.5), the tensioner torque content is 2.5 Nm, the continuous face has a tensioner torque content of 2.8 Nm and 0.5×pitch (integer of 2) has a tensioner torque content of 3.1 Nm. Using a non-integer times the pitch results in less NVH than the continuous face and the integer×pitch.

[0034] FIG. 10 shows twice pitch frequency NVH metric. At 0.4×pitch (non-integer of 2.5), the tensioner torque content is 1.2 Nm, the continuous face has a tensioner torque content of 1.7 Nm and 0.5×pitch (integer of 2) has a tensioner torque content of 2.3 Nm. Using a non-integer times the pitch results in less NVH than the continuous face and the integer×pitch.

[0035] A torsion spring 166 is present between the mounting bracket 162 and the boss portion of the arm 185, adjacent to the non-engagement portion 174 of the second surface 183 and acts upon the arm 168 to bias the arm 168 towards the chain 8. One end 166a of the spring 166 is grounded relative to the mounting bracket 162 and the second end 166b of the spring 166 is grounded relative to the shaft 165. The coils 166c of the spring 166 are wrapped around the pivot axle 164 and present between the boss portion 185, the bracket 162 and second end 183b of the tensioner arm 168.

[0036] A stop 169 is present on the shaft 165 which can interact with the boss portion 185 of the arm 168 if the arm 168 pivots too far.

[0037] FIGS. 5-6 show a tensioner arm 220 with a tensioning face with a pattern including angled or diagonal grooves.

[0038] The pivot axle 164 receives an arm 168 formed of a body 178 having a first end 178a and a second end 178b, a first surface 188 and a second surface 183, opposite the first surface 188. The second surface 183 is defined by a first end 183a, a second end 183b, a first side 183c, a second side 183d and an arcuate boss portion 185. The second surface 183 includes, from a first end 178a to a second end 178b, a chain sliding surface 274, a non-engagement surface 175, and a boss portion 185. The chain sliding surface 274 has a unique pattern of grooves 280 and spacers 281 which engage with or interact with the backs 5 of the chain links 7 of each of the chain strands 8a, 8b. The pattern includes a plurality of radial grooves 280 separated by a spacer 281 of a width w. The unique pattern and associated groove pattern spacing is preferably calculated using equation 1.1 and 1.2. In this embodiment, the width w of the spacer 281 is constant through the pattern. The grooves 280 extend between the first and the second side 183c, 183d and are angled, such that the grooves 280 are not at 90 degrees relative to the first side 183c or the second side 183d. The minimum angle allows for the entire chain width to pass over a given groove during its contact with the tensioner. This angle can be calculated from the tensioner contact length (x) and the width of the chain (y) as tan.sup.−1(y/x). The number of grooves 280 and spacers 281 can vary. The width (w) of the spacers 281 spacing the grooves 280 apart and the number of grooves 280 intentionally break up the chain contact force between the back 5 of the chain links 7 of the chain strand 8a, 8b and the chain sliding face 174 of the tensioner arm 168 to prevent alignment with the chain related orders which are causing NVH within the chain system.

[0039] The non-engagement portion 175 of the second surface 181 does not engage with the chain strands 8a, 8b and extends into the boss portion 185 which defines a hole 186 for rotatably receiving the pivot axle 164.

[0040] A stop 169 is present on the shaft 165 which can interact with the boss portion 185 of the arm 168 if the arm 168 pivots too far.

[0041] FIGS. 11-12 show an alternate tensioner arm 420 with a tensioning face with a pattern including straight grooves. In this embodiment, the width of the spacers 481a, 481b between the plurality of grooves 480 of the chain sliding face 474 varies within the pattern. For example, in the pattern shown, at least one spacer 481b has a width w1, which is greater than a width w of the other spacers 481a of the pattern. The grooves 480 extend between the first and the second sides 183c, 183d and are straight, such that the grooves 480 are at a right angle relative to the first side or the second side 183c, 183d of the second surface 183 of the tensioner arm 420.

[0042] FIG. 13 shows an alternate tensioner arm 620 with a tensioning face 674 with a pattern including diagonal or angled grooves. In this embodiment, the width of the spacers between the plurality of grooves of the chain sliding face varies within the pattern. For example, in the pattern shown, at least one spacer 681b has a width w1 which is greater than width w of the other spacers 681a of the pattern. The grooves 680 extend between the first and second side 183c, 183d and are angled, such that the grooves 680 are at an angle of less than 90 degrees relative to the first side 183c or the second side 183d.

[0043] FIG. 14 shows a flow diagram of a method of applying a unique pattern to a face of a tensioner arm, guide or snubber to alter the NVH.

[0044] In a first step, chain related orders at which NVH occurs within the chain system are determined (step 502). The chain related orders can be determined through computer simulation or through testing of the chain system itself.

[0045] Based on the determined chain related orders which cause NVH issues, a pattern is created for application to the face of the tensioner arm, guide or snubber of a plurality of grooves and spacers (step 506). The specific geometry of the grooves can be determined through simulation, testing, or a combination thereof. This process is iterative through experimentation. Groove geometry should be selected to avoid diminishing that lines up with known chain related orders as identified in equations 1.1. and 1.2.

[0046] The pattern is then applied to chain sliding face of the tensioner arm, guide or snubber (step 508) and the method ends.

[0047] In FIGS. 8-10, it was determined that a chain system had known NVH concerns at half pitch and twice pitch frequencies. Two tensioner face geometries were analyzed and found to have worse performance when the groove geometry was at 0.5×pitch, but better performance at 0.4×pitch.

[0048] FIG. 7 shows another embodiment of a perspective view of a tensioner arm 320 with different axial chain paths 321, 322, 323 each formed of protrusions 380, similar to spacers in other embodiments, depressions 381 similar to the grooves in other embodiments contacting the backs of the links of the chain strand 8a, 8b. In this embodiment, the arm 320 replaces arms of the other embodiments and is attached to the pivot axle 164 of a bracket 162 via hole 386. The arm 320 is formed of a body 378 having a first end 378a and a second end 378b, a first surface 388 and a second surface 383, opposite the first surface 388. The second surface 383 is defined by a first end 383a, a second end 383b, a first side 383c, a second side 383d and an arcuate boss portion 385. The second surface 383 includes, from a first end 378a to a second end 378b, a chain sliding surface 374, a non-engagement surface 375, and a boss portion 385. The chain sliding surface 374 has a unique pattern of protrusions 380 and depressions 381, with the raised portions 380 being present in different areas of the axial chain paths 321, 322, 323 to alter where the backs 5 of the chain links 7 interact with the tensioner arm 320.

[0049] Instead of having grooves and spacers that extend between the sides of the chain sliding face, extending from first side 383c to the second side 383d of the second surface 383 of the arm 320 are three different axial paths. Each axial path has a series of protrusions and depressions placed at different points, such that the chain contacts different protrusions and retrusions of each axial path as the tensioner tensions the chain strand. The protrusions and depressions are placed such that the chain related orders are broken up, similar to grooved embodiments discussed above. Again, dimensionality of these protrusions are governed by equations 1.1 and 1.2.

[0050] The examples of a pattern for application to the chain sliding face are shown as being applied to a tensioner arm, but could also be applied to the chain sliding face of a guide or snubber without deviating from the scope of the invention.

[0051] Accordingly, it is to be understood that the embodiments of the invention herein described are merely illustrative of the application of the principles of the invention. Reference herein to details of the illustrated embodiments is not intended to limit the scope of the claims, which themselves recite those features regarded as essential to the invention.