Tooth skip prevention device

Abstract

To provide a tooth jump protection device which controls chain slack and delays the torque at which a chain tooth jump occurs, thus increasing tooth jump torque performance.SOLUTION: An embodiment comprises: a chain 8 connecting a driving sprocket to a driven sprocket, the chain having a slack strand between the driven sprocket and the driving sprocket and a tight strand between the driven sprocket and the driving sprocket; and a tooth jump protection device at a position where the chain is tangent to the driven sprocket at a first engagement part of the driven sprocket in which the slack strand of the chain is drawn into the driven sprocket. Preferably, the tooth jump protection device is attached to a transfer case.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims one or more inventions disclosed in Provisional Application No. 63 / 140,448, entitled "TOOTH JUMP PROTECTION DEVICE," filed January 22, 2021, and Provisional Application No. 63 / 218,129, entitled "TOOTH JUMP PROTECTION DEVICE," filed July 2, 2021. The benefit under 35 U.S.C. § 119(e) of U.S. provisional patent applications is claimed, and the above applications are incorporated herein by reference. [Background technology]

[0002] FIELD OF THE INVENTION The present invention relates to a device for controlling chain slack accumulation, and more particularly, the location of chain slack accumulation.

[0003] 1a and 1b show schematic locations of slack accumulation relative to the driven sprocket 6 and the driving sprocket 2, respectively, of a conventional chain system 1. The driving sprocket 2 is connected to the driven sprocket 6 via a toothed chain 8. The chain 8 meshes with the sprockets 2 and 6 and transmits rotational motion between them. The chain 8 can skip teeth at either the driven sprocket 6 or the driving sprocket 2 of the chain system 1. If the chain 8 skips teeth near the driven sprocket 6, the resulting chain skip torque is low, while if the chain 8 skips teeth near the driving sprocket 2, the resulting chain skip torque is high. Therefore, forcing tooth skipping to occur only at the driving sprocket 2 can improve the chain's tooth skip torque performance. There are specific locations where slack accumulates relative to the driven sprocket or the driving sprockets 6 and 2, which determine which sprocket the chain 8 is most likely to skip. FIG. 1 a shows the slack buildup occurring in the driven sprocket 6 (indicated by reference numeral 30 ) and FIG. 1 b shows the slack buildup occurring in the driving sprocket 2 (indicated by reference numeral 32 ). Summary of the Invention

[0004] In accordance with one embodiment of the present invention, an anti-skip device is used to control chain slack and delay the torque at which chain skipping occurs, thereby improving skip torque performance. [Brief explanation of the drawings]

[0005] [Figure 1a] 1 shows a schematic diagram of the general location of slack accumulation relative to the driven sprocket in a conventional chain system. [Figure 1b] 1 shows a schematic diagram of the general location of slack accumulation relative to the drive sprocket of a conventional chain system. [Figure 2] FIG. 1 is a schematic diagram of a vertically mounted drive system. [Figure 3] 1 shows a schematic diagram of one embodiment of a tooth jump prevention device (TJPD). [Figure 4] 1 shows a schematic diagram of another embodiment of a TJPD. [Figure 5] A detailed view of the TJPD in Fig. 4 is shown. [Figure 6] A cross section of the TJPD as a fixed position compliant roller within a transfer case is shown. [Figure 7] A detailed view of the TJPD with compliant rollers is shown. [Figure 8a] 1 shows a schematic diagram of a TJPD, a ramped shock absorber engaged with a chain in a transfer case. [Figure 8b] 1 shows a schematic diagram of the TJPD of a sloped buffer when tension is applied to the opposite chain strand. [Figure 9] 1 shows a prior art buffer engaged with a chain. [Figure 10] 1 illustrates another embodiment of a TJPD. [Figure 11a]1 shows a schematic diagram of a buffer spaced a specific distance relative to the driven sprocket and a specific gap relative to the chain. [Figure 11b] This shows the accumulation of slack relative to the cushion in Figure 11a. [Figure 12] A diagram of the TJPD with the shock absorber mounted inside the transfer case is shown. [Figure 13] A schematic diagram of a TJPD of a spring-biased compliant roller moving towards engagement with a chain is shown. DETAILED DESCRIPTION OF THE INVENTION

[0006] In one embodiment of the present invention, a tooth jump prevention device (TJPD) can be used to control chain slack in a transfer case so that chain slack occurs only on the drive sprocket, resulting in higher tooth jump torque. Higher tooth jump torque capability allows for a reduction in chain width.

[0007] In the system layout of FIG. 2, the drive and driven sprockets 103, 104 associated with the drive and driven shafts 2, 6, respectively, are shown in a vertical orientation, with the driven sprocket 6 on the bottom and the drive sprocket 2 on the top within the transfer case 107. Chain 8 connects drive sprocket 2 to driven sprocket 6. Between drive sprocket 2 and driven sprocket 8, the chain has a slack strand 8b and a tight strand 8a. As the transfer case approaches a vertical orientation, gravity favors the development of slack at the interface between the driven sprocket 6 and chain 8 within the transfer case 107. A tooth skip and chain slack study for this system layout was conducted using a rigid guide or tooth jump prevention device (TJPD) 120 mounted at the entrance (retraction side) of slack strand 8b, which meshes with the driven sprocket 6 at various radial offsets. Through research, it was determined that the TJPD device 120 should preferably be positioned a radial distance away from the center of the sprocket to avoid interference with the natural engagement of the chain with the sprocket. This positioning increases as the chain wears. This distance will vary depending on the system layout, chain design, and the end of the chain's life.

[0008] The TJPD 120 preferably provides sufficient load to keep the chain 8 engaged with the driven sprocket 6, with sufficient load based on stiffness requirements. The stiffness requirements of the TJPD 120 depend on the applied peak torque, the radial offset of the TJPD 120, and the chain type and design. As the applied torque increases, the load required from the TJPD 120 to maintain proper engagement also increases. As the chain 8 moves radially outward, deflecting the TJPD 120, the force required from the TJPD 120 to maintain engagement of the driven sprocket increases. From a chain type and design perspective, chain links with steeper flank pressure angles require less force from the TJPD 120. Note that the TJPD 120 must be flexible enough to withstand catastrophic driven sprocket jump if the chain 8 were to be forced to wedged between the driven sprocket 6 and the TJPD 120.

[0009] 2 shows the transfer case in a vertical position, the system can be oriented at any angle within the scope of application. The TJPD 120 is located at the entrance to the driven sprocket 6. More specifically, the TJPD 120 is positioned at a location where the chain 8 is tangent to the driven sprocket 6 at the initial engagement of the driven sprocket 6 with the slack strand 8b of the chain 8 (e.g., the entrance of the chain 8 to the driven sprocket 6).

[0010] In one embodiment, the integral locking locations TJPDs 130a, 130b are installed on the driven sprocket 6. The TJPDs 130a, 130b are located at the entrance and / or exit (payout side) of the driven sprocket 6, regardless of the orientation angle of the transfer case. More specifically, the TJPD 130a is positioned at a location where the chain 8 is tangent to the driven sprocket 6 at the initial engagement of the driven sprocket 6 with the slack strand 8b of the chain 8 (e.g., the entrance of the chain 8 to the driven sprocket 6). The TJPD 130b is positioned at a location where the chain 8 is tangent to the driven sprocket 6 at the final engagement of the driven sprocket 6 with the tight strand 8a of the chain (e.g., the exit of the chain 8 from the driven sprocket 6).

[0011] The integral fixed position TJPDs 130a, 130b have a body 131 fabricated from plastic, steel, or aluminum and have a flat chain face 132 that interacts with the chain 8, which may include an elastomeric coating. The integral fixed position TJPDs 130a, 130b may be snubbers that are bolted to the transfer case 107 relative to the chain 8 and driven sprocket 6. The thickness of the elastomeric coating varies depending on the chain and design layout. Furthermore, the body 131 and / or elastomeric coating thickness of the TJPDs 130a, 130b on either side of the driven sprocket 6 may be the same or different.

[0012] 4-5 show another embodiment of a TJPD 175 mounted to the transfer case 107 and adjacent to the chain 8 and driven sprocket 6. In this embodiment, the TJPD 175 is an "L-shaped" one-piece multi-sided ramp 140 with a mounting bracket 141. The mounting bracket 141 may be integrally formed with the multi-sided ramp 140. In one embodiment, the mounting bracket 141 and the one-piece multi-sided ramp 140 are formed from a single steel plate. The mounting bracket 141 is at an approximately 90-degree angle relative to a first flat surface 142 of the multi-sided ramp 140. In other words, the mounting bracket is the vertical portion of the "L" and the multi-sided ramp 140 is the horizontal portion of the "L." The multi-sided ramp 140 is preferably flexible and has a smooth contour.

[0013] The multi-sided ramp 140 consists of a first flat surface 142 at approximately 90 degrees to the mounting bracket 141, a first transition ramp 143, an angled ramp 144, a second transition ramp 145, and a second flat surface 146. The second flat surface 146 has a face 146a that is offset from the chain 8 by a small gap 147 when mounted. As the chain 8 wears or stretches, the gap 147 decreases, allowing contact between the chain 8 and face 146a during normal operation of the chain 8. As the chain 8 rotates and tooth skipping occurs, face 146a of the second flat surface 146 of the TJPD 175 provides a reaction force to the chain 8 to maintain engagement with the driven sprocket 6 and prevent chain slack from building up on the driven sprocket 6.

[0014] Alternatively, the multi-sided lamp 140 can include offset flat surfaces with a cantilever between the offset surfaces. More specifically, the multi-sided lamp 140 can include a first flat surface 142, a second flat surface 146, and an angled lamp 144 without transition lamps 143, 145. The angled lamp 144 is preferably flexible and has a smooth contour.

[0015] Surface 146a may include a plastic or elastomeric surface to minimize noise, vibration, and harshness (NVH) concerns and improve wear resistance of TJPD 140. TJPD 140 is preferably mounted such that surface 146a of second planar surface 146 is diametrically disposed relative to driven sprocket 6 and / or driving sprocket 2 and is positioned at the inlet and / or outlet of driven sprocket 6 or driving sprocket 2 regardless of the angle of orientation of the transfer case. More specifically, at least the first TJPD 140 is positioned at a location where chain 8 is tangent to driven sprocket 6 at the initial engagement of driven sprocket 6 with slack strand 8b of chain 8 (e.g., the inlet of chain 8 to driven sprocket 6). The second TJPD 140 can be positioned at a location where the chain 8 is tangent to the driven sprocket 6 at the final engagement between the driven sprocket 6 and the tight strand 8a of the chain (e.g., at the exit of the chain 8 from the driven sprocket 6).

[0016] Alternatively, the TJPD 140 can include a stop 180, as shown in FIG. 10 . In this embodiment, the stop 180 is attached to the mounting bracket 141. The stop 180 is preferably located adjacent to the first transition ramp 143 of the multi-sided ramp 140. The stop 180 can be a tab or other such protrusion. The stop 180 can be integrally formed with the mounting bracket 141.

[0017] The addition of stop 180 reduces bending of the entire multi-sided ramp 140 at the connection 191 between the multi-sided ramp 140 and the bracket 141. Additionally, the addition of stop 180 reduces bending at the first transition ramp 143, resulting in a more even distribution of stresses on the multi-sided ramp 140.

[0018] 6 shows an embodiment in which the TJPDs 190a, 190b are fixed position rollers. Each TJPD 190a, 190b includes a bolt 195 that is fixedly attached to the transfer case 107. Surrounding and free to rotate about the bolt 195 is a rolling element 196. The rolling element 196 preferably has an elastomeric coating.

[0019] TJPDs 190a and 190b are installed on the driven sprocket 6. TJPDs 190a and 190b are located at the inlet and / or outlet of the driven sprocket, regardless of the orientation angle of the transfer case. More specifically, TJPD 190a is positioned at a location where the chain 8 is tangent to the driven sprocket 6 at the initial engagement between the driven sprocket 6 and the slack strand 8b of the chain 8 (e.g., at the entrance of the chain 8 to the driven sprocket 6). TJPD 190b is positioned at a location where the chain 8 is tangent to the driven sprocket 6 at the final engagement between the driven sprocket 6 and the tight strand 8a of the chain (e.g., at the exit of the chain 8 from the driven sprocket 6).

[0020] 7 shows an embodiment in which the TJPD 180 is a ramped roller TJPD. The TJPD 180 is mounted within the transfer case 107 and adjacent to the chain 8 and driven sprocket 6.

[0021] The mounting bracket 151 is at approximately a 90 degree angle relative to a first flat surface 152 that transitions into a first transition ramp 153, an angled ramp 154, and a compliant roller holder 155 that receives the compliant roller 156. In other words, the mounting bracket is the vertical portion of an "L" and the first transition ramp 153 is the horizontal portion of the "L." The mounting angle of the bracket 151 relative to the compliant roller 156 can be any angle that mounts both the TJPDs 150a, 150b to the transfer case 107 and allows the compliant roller 156 to engage the chain 8.

[0022] The TJPDs 180 are preferably mounted such that the face compliant rollers 156 are diametrically disposed on the driven sprocket 6 and / or the driving sprocket 2 and are positioned at the entrance and / or exit of the driven sprocket 6 or the driving sprocket 2 regardless of the orientation angle of the transfer case. More specifically, at least a first TJPD 180 is positioned at a location where the chain 8 is tangent to the driven sprocket 6 (e.g., at the entrance of the chain 8 to the driven sprocket 6) at the initial engagement of the driven sprocket 6 with the slack strand 8b of the chain 8. A second TJPD 180 can be positioned at a location where the chain 8 is tangent to the driven sprocket 6 at the final engagement of the driven sprocket 6 with the tight strand 8a of the chain (e.g., at the exit of the chain 8 from the driven sprocket 6).

[0023] The face compliant roller 156 may be made of plastic. Alternatively, the face compliant roller 156 may be made of plastic or other materials and may be coated with an elastomer to reduce wear. The face compliant roller 156 may be a single roller mounted in a compliant roller holder 155, as shown in FIGS. 7 and 13, or multiple distinct rollers mounted on either side of the compliant roller holder 155.

[0024] In an alternative embodiment shown in FIG. 13, a TJPD 170 with a face compliant roller 156 is spring-biased 157 toward engagement with the chain 8, further concentrating system slack accumulation at a specific point on the driving or driven sprocket 2, 6 to reduce contact force. The face compliant roller 156 is received on a compliant roller holder 155 that is integral with an arm 159. The face compliant roller 156 reduces the amount of friction against the chain 8 compared to a chain sliding across a conventional tensioner arm.

[0025] The arm 159 is pivotally attached to the mounting bracket 151 via a pivot pin 158 received in a pivot hole 168 in the arm 159 at a second end 159b of the arm 159 opposite the compliant roller holder 155 at the first end 159a. The pivot pin 158 is attached to the mounting bracket at a 90 degree angle. The arm 159 is preferably rigid.

[0026] A spring 157 is located between the first end 159a of the arm 159 and the bracket 151, biasing the arm 159 and, therefore, the face compliant roller 156. The spring forces at the entrance and exit of the chain 8 from each sprocket 2, 6, or either the driven sprocket 6 or the driving sprocket 2, may be different or the same. The spring 157 may be a torsion spring, a blade spring, or another type of spring. The use of the spring 157 can increase compliance and reduce contact force. Additionally, the spring 157 used may have a limited stroke range so that, in the first position, the spring 157 biases the face compliant roller 156 such that the face compliant roller 156 does not engage the chain 8 and there is clearance between the face compliant roller 156 and the chain 8. When the chain 8 contacts the face compliant roller 156 with sufficient force to overcome the spring preload, the face compliant roller 156 moves to a second position by rotating an arm 159 connected to the compliant roller holder 155, which pivots the arm 159 relative to the mounting sprocket 151 via a pivot pin 158. The spring preload is utilized to prevent chain jump. The spring load is preferably adjusted to the force necessary to prevent jumping and, therefore, reduce or prevent chain slack on the driven sprocket 6.

[0027] The TJPDs 170 are preferably mounted such that the face compliant rollers 156 are diametrically disposed relative to the driven sprocket 6 and / or the driving sprocket 2 and are positioned at the entrance and / or exit of the driven sprocket 6 or the driving sprocket 2, regardless of the angle of orientation of the transfer case. More specifically, at least a first TJPD 170 is positioned at a location where the chain 8 is tangent to the driven sprocket 6 at the initial engagement of the driven sprocket 6 with the slack strand 8b of the chain 8 (e.g., the entrance of the chain 8 to the driven sprocket 6). A second TJPD 170 can be positioned at a location where the chain 8 is tangent to the driven sprocket 6 at the final engagement of the driven sprocket 6 with the tight strand 8a of the chain (e.g., the exit of the chain 8 from the driven sprocket 6).

[0028] 8a-8b show another embodiment of a TJPD. In this embodiment, the TJPD is a biased snubber 160. The biased snubber 160 is attached to the drivetrain transfer case 107. The biased snubber 160 includes a body 161 having a first end 162, a second end 163 opposite the first end 162, and a length L between the first end 162 and the second end 163, a snubber face 164, and a second face 165 opposite the snubber face 164. An intended angle α (alpha) exists between the first end 162 and the second end 163 relative to a line 193 extending along the snubber face 164 from the first end 162 to the second end 163 and parallel to the snubber face 164. The intended angle α is between 0 and 5 degrees, and more preferably greater than 0 degrees.

[0029] The biased buffer 160 creates an intended angle α between the path of the chain 8 and the buffer surface 164, such that the intended angle α exists between the chain path and the buffer surface 164. The buffer surface 164 is shaped so that the buffer surface 164 more closely resembles the chain 8 near the driven sprocket 6 compared to the drive sprocket 2. The intended α angle forces chain slack to accumulate near the chain exit at the drive sprocket 2, as indicated by reference numeral 32. As shown in FIG. 8a, the biased buffer 160 is completely outside the chain path when tension is applied to the adjacent chain strand.

[0030] When tension is applied to the opposing chain strand, slack accumulates in the chain strand adjacent to the biased buffer 160, and the intended angle α (alpha) of the biased buffer 160 forces the excess chain to converge at a known location, resulting in improved tooth skipping, as shown in Figure 8b. Thus, slack accumulation exists only near the drive sprocket 2 and can be utilized to control chain slack within the transfer case, thereby limiting chain slack to drive sprocket 2 and resulting in higher tooth skipping torque. Higher tooth skipping torque capability allows for a reduction in chain width.

[0031] It should be noted that the biased buffer 160 may also be mounted at a target distance relative to the driven sprocket and within a target or specific chain-to-buffer gap to prevent slack buildup on the driven sprocket 6 and force slack buildup near the driving sprocket 2, as described below in connection with Figures 11a-11b.

[0032] 11a-11b illustrate one embodiment of a TJPD in which a buffer 200 is installed at a specific or target distance relative to the driven sprocket 6 and within a target or specific chain-to-buffer gap to prevent slack accumulation relative to the driven sprocket 6 and force slack accumulation near the driving sprocket 2. The buffer 200 has a body 201 having a first end 202 and a second end 203 and a first face 205 and a second face 204. The second face 204 is adjacent to the chain 8. Optionally, the second face 204 may include a pad or elastomeric surface to reduce noise, vibration, and harshness (NVH) concerns. The buffer location is positioned a gap distance g1 from the chain and is biased a distance d1 from the driven sprocket 6. These distances g1 and d1 are determined by the attachment points of the chain 8 and sprockets 2 and 6 relative to the transfer case 107.

[0033] The buffer 200 is installed between the driven sprocket 6 and the driving sprocket 2 at a specific distance d1 from the centerline C1 of the driven sprocket 6 and at a specific gap distance g1 between the second surface 204 and the chain 8. In one example, the gap distance g1 between the chain 8 and the buffer 200 is in the range of 0 to 7 mm. In another embodiment, this range may be 0 to 1 mm. In another embodiment, this range may be 0 to 2 mm. In yet another example, the gap distance g1 is 0.5 mm or less. Setting the gap distance between the chain 8 and the buffer 200 reduces the contact force and wear of the buffer 200. Using the chain pitch length, the distance d1 would be approximately two chain pitch lengths. For example, for a 9.525 mm pitch chain, d1 would be approximately 19 mm. For an 11.039 mm pitch chain, the distance d1 would be approximately 22 mm.

[0034] When buffer 200 applies tension to the chain strand opposite the adjacent chain strand, gap distance g1 and distance d1 cause slack to accumulate in the chain strand adjacent buffer 200, forcing excess chain to accumulate at a known location near drive sprocket 2, resulting in higher tooth skipping torque. Higher tooth skipping torque capability allows for a smaller chain width to be used.

[0035] FIG. 9 illustrates a conventional or traditional bumper. The conventional bumper 50 is not angled; instead, it is straight or approximately 180 degrees along its entire length between the first end 51 and the second end 52, resulting in the entire bumper surface 53 interacting with the chain strand 8 and a small gap of approximately 0.1 mm between the conventional bumper 50 and the chain. Slack accumulates near the driving sprocket 2 at location 32 and near the driven sprocket 6 at location 30. Thus, slack is allowed to accumulate near both the driving sprocket 2 and the driven sprocket 6, potentially resulting in skipping of either sprocket.

[0036] 12 shows a TJPD 300 mounted to a transfer case 107 and positioned adjacent to a chain 8 and a driven sprocket 6. In this embodiment, the TJPD 300 is a one-piece multi-sided ramp 310 with a mounting bracket 301 and a bumper 302.

[0037] The mounting bracket 301 may be integrally formed with the multi-faceted lamp 310. Additionally, the mounting bracket 301 may be integrally formed with the cushion 302.

[0038] The cushion 302 has a first planar surface 302a and a second, opposite planar surface 302b adjacent the chain 8. Attached to the second planar surface 302b is a pad or elastomeric pad 303. The pad 303 contacts the chain 8.

[0039] Also mounted on mounting bracket 301 is multi-sided lamp 310. Multi-sided lamp 310 has a first body portion 304 with a flat surface coupled to mounting bracket 301 and a sloped second body portion 305. Sloped second body portion 305 is coupled to first transition ramp 306, which is coupled to first flat surface 307. Attached to face 307a of second flat surface 307 is a pad or elastomeric surface 309.

[0040] When installed, the pad 309 is offset from the chain 8 by a small gap. For example, the gap between the pad 309 and the chain 8 is between 0.5 and 1.5 mm. As the chain 8 wears or stretches, the gap decreases, allowing contact between the chain 8 and the pad 309 during normal chain operation. As the chain 8 rotates and tooth skipping occurs, the pad 309 of the TJPD 300 applies a reaction force to the chain 8, keeping it engaged with the driven sprocket 6 and preventing chain slack from building up on the driven sprocket 6. The pad 303 maintains contact with the chain 8 during normal chain operation. The pad 303 acts like a buffer to dampen chain resonance and contacts the chain when it enters a resonant state.

[0041] The TJPD 300 is preferably mounted such that the pads 309 of the multi-sided ramps 310 are positioned on the driven sprocket 6 or driving sprocket 2 along the diameter of the driven sprocket 6 or driving sprocket 2, and are positioned at the entrance and / or exit of the driven sprocket regardless of the angle of orientation of the transfer case.

[0042] More specifically, at least the first TJPD 300 is positioned at a location where the chain 8 is tangent to the driven sprocket 6 at the initial engagement between the driven sprocket 6 and the slack strand 8b of the chain 8 (e.g., at the entrance of the chain 8 to the driven sprocket 6). The second TJPD 300 can be positioned at a location where the chain 8 is tangent to the driven sprocket 6 at the final engagement between the driven sprocket 6 and the tight strand 8a of the chain (e.g., at the exit of the chain 8 from the driven sprocket 6).

[0043] In one embodiment, the mounting bracket 301 and the bumper 302 are formed from a single steel plate. The mounting bracket 301 is at an angle of approximately 90 degrees relative to the first planar surface 302a of the bumper 302.

[0044] The buffer 302 of the TJPD 300 further reduces noise, vibration, and harshness (NVH) by controlling strand resonances associated with the chain system, while the multi-sided ramp 310 of the TJPD 300 limits the accumulation of slack in the driven sprocket 6.

[0045] Two TJPDs 130, 140, 150, 160, 170, 180, 190, 200, 300 are shown on either side of the driven sprocket 6, however, one TJPD can be positioned at a specific or target distance relative to the driven sprocket 6.

[0046] In another embodiment, either a single TJPD or two TJPDs may be present on either side of the driving sprocket 2 to force the driven sprocket 6 to experience slack buildup.

[0047] Although not shown, in alternative embodiments, the two TJPD devices mounted along the diameter of the driven sprocket and / or the driving sprocket can be different devices. Any combination of TJPDs disclosed within the scope of the application can be present at the entry and exit points of the chain from the driven sprocket 6. Thus, a first TJPD at the initial engagement of the driven sprocket 6 with the slack strand 8b of the chain 8 (e.g., at the entry of the chain 8 into the driven sprocket 6) can be the same as or different from a second TJPD positioned at the location where the chain 8 is tangent to the driven sprocket 6 at the final engagement of the driven sprocket 6 with the tight strand 8a of the chain (e.g., at the exit of the chain 8 from the driven sprocket 6).

[0048] For example, the integral fixed-position TJPD 130 may be attached at the driven sprocket 6's initial engagement with the slack strand 8b of the chain 8 (e.g., at the entry of the chain 8 into the driven sprocket 6), and the second TJPD may be an L-shaped integral multi-sided ramp TJPD 140 attached at the driven sprocket 6's final engagement with the tight strand 8a of the chain. In another example, the fixed-position compliant roller TJPD 150 may be attached at the driven sprocket 6's initial engagement with the slack strand 8b of the chain 8 (e.g., at the entry of the chain 8 into the driven sprocket 6), and the second TJPD may be a buffer TJPD 300 attached at the driven sprocket 6's final engagement with the tight strand 8a of the chain. The above examples are not limiting, and other combinations are possible.

[0049] Additionally, along the chain span between the driven and driving sprockets, the TJPDs attached to opposing chain strands may also be different. For example, one TJPD may be a biased buffer TJPD 160, and the opposing TJPD attached relative to the opposing chain strand may be a buffer TJPD 200. The above examples are not limiting, and other combinations are possible.

[0050] In yet another embodiment, a single TJPD 130 , 140 , 150 , 160 , 170 , 180 , 190 , 300 may be positioned at the entrance of the slack strand 8 b that is meshed with the driven sprocket 6 .

[0051] In yet another embodiment, a single TJPD 160, 200 is positioned relative to one of the strands 8a, 8b of the chain 8.

[0052] In another embodiment, when the transfer case is installed in a horizontal position, the opposite midpoints correspond to the 12 o'clock and 6 o'clock positions on a clock along the central diameter of the driven sprocket 6 and / or the driving sprocket 2. The TJPDs in the above embodiments are installed at opposite midpoints of the driven sprocket 6 and / or the driving sprocket 2.

[0053] In another embodiment, when the transfer case is mounted in a vertical position, the opposite midpoints correspond to 3 o'clock and 9 o'clock on the clock of driven sprocket 6 and / or driving sprocket 2. The TJPDs in the above embodiments are installed at opposite midpoints on driven sprocket 6 and / or driving sprocket 2.

[0054] Accordingly, it is to be understood that the embodiments of the invention described herein are merely illustrative of the application of the principles of the invention. Reference herein to details of illustrated embodiments is not intended to limit the scope of the claims, but rather to recite those features regarded as essential to the invention.

Claims

1. A chain drive system in a transfer case, comprising: A drive sprocket; A driven sprocket; a chain connecting the driving sprocket to the driven sprocket, the chain having a slack strand and a tight strand between the driven sprocket and the driving sprocket; a first anti-skip device that attaches the chain to a first engagement portion of the driven sprocket where the slack strand of the chain is pulled into the driven sprocket, whereby slack in the chain is created adjacent the driving sprocket and increases the skipping torque of the chain drive system; and A chain drive system comprising: the first anti-skip device comprises a first anti-skip device mounting bracket secured to the transfer case and a first anti-skip device ramp connected to the first anti-skip device mounting bracket, the first anti-skip device ramp including a first anti-skip device flat surface and a first anti-skip device second flat surface connected to the first anti-skip device flat surface, the second anti-skip device flat surface having a first anti-skip device face for engaging with the chain engaged with the driven sprocket and for preventing chain slack from accumulating on the driven sprocket, the first anti-skip device flat surface is perpendicular to the first anti-skip device mounting bracket, and the first anti-skip device ramp is flexible. Chain drive system.

2. a second anti-skip device attached to a second engagement portion of the driven sprocket where the taut strand of the chain is fed out from the driven sprocket; The second tooth skip prevention device is a bracket fixed to the transfer case; a lamp connected to the bracket; the lamp includes a first planar surface and a second planar surface; the second flat surface of the second anti-skip device having a surface for engaging the chain engaged with the driven sprocket and for preventing chain slack from building up on the driven sprocket; the first flat surface is perpendicular to the bracket, and the ramp of the second anti-skip device is flexible; The chain drive system of claim 1 .

3. a second anti-skip device attached to a second engagement portion of the driven sprocket where the taut strand of the chain is fed out from the driven sprocket; The second tooth skip prevention device is a bracket fixed to the transfer case; a ramp connected to the bracket, the ramp having at least a first flat surface, an angled portion, and a roller holder; at least one roller mounted in the roller holder that engages the chain to maintain the chain in engagement with the driven sprocket and prevent slack from building up in the chain on the driven sprocket; the first flat surface is perpendicular to the bracket, and the ramp of the second anti-skip device is flexible; The chain drive system of claim 1 .

4. a second anti-skip device attached to a second engagement portion of the driven sprocket where the taut strand of the chain is fed out from the driven sprocket; The second tooth skip prevention device is a bracket secured to the transfer case, the bracket having a pivot pin extending perpendicularly therefrom; an arm having a body with a first end, a second end, a roller holder at the second end, and a hole at the first end for receiving the pivot pin; at least one compliant roller mounted in the roller holder for engagement with the chain to maintain the chain in engagement with the driven sprocket and to prevent chain slack from building up on the driven sprocket; a torsion spring mounted between the bracket and the arm and biasing the first end of the arm on the pivot axle toward the chain; The chain drive system of claim 1 .

5. a second anti-skip device attached to a second engagement portion of the driven sprocket where the taut strand of the chain is fed out from the driven sprocket; The second tooth skip prevention device is a mounting bracket secured to the transfer case; a ramp connected to the bracket, the ramp including a first flat surface of a first body portion connected to an angled portion of a second body portion, the angled portion connected to a second flat surface through a first transition portion, the second flat surface maintaining the chain in engagement with the driven sprocket and preventing chain slack from building up on the driven sprocket; a body of the second anti-skip device fixed to the bracket and having a surface for engaging the chain between the driven sprocket and the driving sprocket, the surface being parallel to the first flat surface of the first body portion; The first flat surface is perpendicular to the bracket, and the ramp of the second anti-skip device is flexible. The chain drive system of claim 1 .

6. 6. The chain drive system of claim 2, further comprising a stop, a tab or protrusion attached to the bracket, that reduces bending of the ramp.

7. 6. The chain drive system of claim 5, further comprising a first pad attached to the engaging surface of the body of the second anti-skip device for engaging the chain, and a second pad attached to the second flat surface.

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