Method of applying tension to increase drive train jump torque capacity

Abstract

A chain tensioning device that counteracts the natural accumulation of slack in a chain. In controlling chain slack, the torque that occurs in chain jumps is delayed, resulting in higher jump torque performance.

Description

[0001] Cross-reference to related applications

[0002] This application claims one or more inventions disclosed in Provisional Application No. 63 / 140,457, entitled “Chain Tensioner,” filed January 22, 2021. The benefit of this U.S. Provisional Application is claimed under 35 USC §119(e), and the aforementioned application is incorporated herein by reference. Background Technology

[0003] This invention relates to chain tensioners, and more particularly to a chain tensioner for a transmission system for increasing jump torque.

[0004] When a chain travels between multiple sprockets, tensioning devices such as hydraulic tensioners are used as control mechanisms for power transmission chains or similar power transmission devices in engine timing systems. In this device, the chain transmits power from the drive shaft to the driven shaft, causing a portion of the chain to slack while another portion remains taut. It is generally important to apply and maintain a certain level of tension in the chain to prevent noise, slippage, or, in the case of toothed chains, tooth misalignment (tooth skipping). Preventing this slippage is particularly important in the case of chain-driven camshafts in internal combustion engines, as tooth skipping can cause camshaft timing to disengage, potentially leading to damage or engine malfunction.

[0005] In the harsh environment of an internal combustion engine, various factors can cause fluctuations in chain tension. For example, wide variations in temperature and coefficients of thermal expansion between different engine components can cause chain tension to fluctuate between excessively high and low levels. Wear and tear on power transmission system components during prolonged use can lead to a decrease in chain tension. Furthermore, torque vibrations caused by the camshaft and crankshaft result in significant changes in chain tension. Reverse rotation of the engine, for example, during engine stops or failed attempts to start, can also cause fluctuations in chain tension. For these reasons, a mechanism is needed to eliminate excessive tension on the tensioned side of the chain and ensure the necessary tension on the slack side.

[0006] Currently in engine timing systems, dampers, guides, or tensioners are used to tension at least one segment of the chain to improve noise, vibration, and harshness (NVH) by controlling chain segment resonance. However, this chain management is not seen in drivetrain transfer cases.

[0007] For many reasons, tensioning devices have not yet been used in drivetrain gearboxes. Existing technology has taught that tensioning a slack section to tighten the slack portion of the chain can delay tooth skipping, which is equivalent to high tension and results in greater skip torque. However, the tensioning device constantly applies a load to at least one segment of the chain, reducing system efficiency. While high tension leads to greater skip torque, it significantly worsens system efficiency. The advantages associated with improved skip torque performance do not surpass those of existing technologies. Figure 1 The jump torque (Nm) shown represents the efficiency sacrifice of the tensioner spring load (N). The improvement in jump torque increases with increasing tensioner spring load. An improvement in jump torque can be observed when the tensioner spring load exceeds 65N and increases to 220N. However, as the tensioner spring load increases, system efficiency decreases, as in the prior art. Figure 2 As shown. In Figure 2 In this study, the system without a tensioner resulted in a system efficiency of approximately 99.3%, while the 215N spring with a larger jump torque resulted in a system efficiency of approximately 96.8%, which is significantly higher. Summary of the Invention

[0008] According to one embodiment of the present invention, a chain tensioning device counteracts the natural accumulation of chain slack. When controlling chain slack, the torque that causes chain jumps is delayed, resulting in higher jump torque performance. Attached Figure Description

[0009] Figure 1 The graph shows the jump torque (Nm) of a conventional tensioner used in an engine timing system versus the tensioner spring load (N).

[0010] Figure 2 A graph showing the efficiency of a conventional powertrain gearbox depending on the spring load used is presented.

[0011] Figure 3a A schematic diagram shows the approximate location of the slack accumulation relative to the driven sprocket.

[0012] Figure 3b A schematic diagram shows the approximate location of the slack accumulation relative to the drive sprocket.

[0013] Figure 4 A schematic diagram of a chain system with a tensioning device applied asymmetrically toward the driven sprocket is shown.

[0014] Figure 5a This is a schematic diagram of the chain system within the transmission gearbox, which includes the first and second multi-pivot torsion spring tensioners of the first embodiment.

[0015] Figure 5b yes Figure 5aDetailed view of the first multi-pivot torsion spring tensioner.

[0016] Figure 5c yes Figure 5a Detailed view of the second multi-pivot torsion spring tensioner.

[0017] Figure 6 This is a partial view of the transmission gearbox including the torsion spring tensioner of the second embodiment.

[0018] Figure 7 A schematic diagram of a transmission gearbox chain system including a leaf spring tensioner according to a third embodiment is shown.

[0019] Figure 8 A schematic diagram of a chain system with a two-stage tensioner is shown. Detailed Implementation

[0020] Figure 3a and 3b The approximate positions of slack accumulations 30 and 32 relative to the driven sprocket 6 and drive sprocket 2 of chain system 1 are shown, respectively. Drive sprocket 2 is connected to driven sprocket 6 via toothed chain 8. Chain 8 meshes with sprockets 2 and 6, transmitting rotational motion between the sprockets. Testing revealed that chain 8 can skip on either driven sprocket 6 or drive sprocket 2 of chain system 1. Skipping near driven sprocket 6 results in lower skip torque, while skipping near drive sprocket 2 results in higher skip torque. Therefore, forced skipping only on drive sprocket 2 allows for higher skip torque performance of the chain. Testing identified specific positions relative to driven or drive sprockets 6 and 2 where chain slack is collected, thus determining which sprocket chain 8 will skip. Figure 3a The diagram shows the slack accumulation occurring at the driven sprocket 6, indicated by reference numeral 30, while... Figure 3b The diagram shows the relaxation accumulation occurring at the drive sprocket 2, indicated by reference numeral 32 in the figure.

[0021] In a gearbox, placing at least one conventional tensioning device at a specific location on the chain segment between the driven sprocket and the drive sprocket can force the drive sprocket to jump, thereby increasing the chain's jump torque rating and thus allowing the use of narrower chains while maintaining the system's jump torque requirements. Therefore, forcing the drive sprocket to jump for narrow chains and sprockets offers the advantages of reduced mass and lower cost. For example, by forcing the jump closer to the drive sprocket, the chain width can be reduced by 1 / 4 inch (6.35 mm). Thus, in conventional chain systems requiring a 1.5-inch wide chain (38.10 mm), the application of the tensioning device of this invention allows for the use of narrower chains, such as 1.25 inches (31.75 mm) in width. Different application designs and requirements can allow for width reductions greater than or less than 1 / 4 inch (6.35 mm). Embodiments of this invention can be applied to chains with diameters between 1 / 2 inch (12.70 mm) and 2 inches (50.8 mm).

[0022] Further research has determined that when the tensioning device is applied asymmetrically toward the driven sprocket, a low-force spring can force the drive sprocket to jump, such as... Figure 4 As shown. In Figure 4 In this embodiment, a first tensioner device 40 having a single pivot point has a chain sliding surface 44 that engages with a first segment 8a of chain 8 and is mounted relative to chain 8 in a first mounting position. In one embodiment, the first tensioner device 40 may be triangular in shape, with a single pivot pin 42 received in a pivot pin hole 54 located at a center point opposite to the chain sliding surface 44. Opposite to the first tensioner device 40 is a second tensioner device 48, which has a single pivot point and a chain sliding surface 52 that engages with a second segment 8b of chain 8 and is mounted in a second mounting position. In one embodiment, the second tensioner device 48 may be triangular in shape, with a single pivot pin 50 received in a pivot pin hole 55 at a center point opposite to the chain sliding surface 52. The pivot pins 42 and 50 are preferably mounted to a transmission gearbox. It should be noted that the first tensioner device 40 and the second tensioner device 48 are positioned or installed closer to the driven sprocket 6 than the drive sprocket 2. This causes the tension on any segment 8a, 8b of the chain 8 to be applied asymmetrically toward the driven sprocket 6, thus allowing slack in the chain 8 to instead accumulate near the drive sprocket 2 at position 32, such as... Figure 3b As shown in the image.

[0023] Furthermore, as tension is applied to the driven sprocket 6, forcing tooth skipping to occur on the drive sprocket 2, a low-force spring is required on the tensioner assembly, such as a 25N torsion spring, resulting in an efficiency of approximately 98.9% and reducing the negative impact on system efficiency. Figure 6 As shown. Additionally, as is generally known, tensioning chain segments can improve NVH (noise, vibration, and harshness) by controlling chain segment resonance.

[0024] In a preferred embodiment, the chain system in the transmission gearbox includes at least a chain with a drive sprocket, a driven sprocket, and at least one tensioning device. Compared to a conventional chain system in a transmission gearbox, the chain, drive sprocket, and driven sprocket are reduced in width by 1 / 4 inch (6.35 mm). The mass of this at least one tensioning device is less than the mass saved in reducing the width of the chain, drive sprocket, and driven sprocket. For example, if a conventional application requires a 1.5” (38.10 mm) wide chain, the present invention uses a narrower 1.25” (31.75 mm) wide chain with the same efficiency. Different application designs and requirements may allow for width reductions greater than or less than 1 / 4” (6.35 mm). Note that the 1 / 4-inch width reduction relates to common chain size naming conventions. Actual dimensions vary slightly. Furthermore, when the chain is narrower, the sprockets can also be narrower.

[0025] Figures 5a-8 A chain system in a transmission gearbox is shown, which includes at least one tensioning device that reduces the size and weight of the chain system while maintaining system efficiency and without increasing cost.

[0026] Figures 5a-5c A schematic diagram of a chain system within a transmission gearbox, including the first and second multi-pivot torsion spring tensioners of the second embodiment, is shown. The transmission gearbox 60 receives a drive sprocket 2, a driven sprocket 6, a chain 8, a first multi-pivot torsion spring tensioner 61, and a second multi-pivot torsion spring tensioner 63. The drive sprocket 2 is connected to the driven sprocket 6 via a toothed chain 8. The chain 8 meshes with sprockets 2 and 6, transmitting rotational motion between the two sprockets.

[0027] The first multi-pivot torsion spring tensioner 61 and the second multi-pivot torsion spring tensioner 63 each have mounting brackets 62a and 62b, the mounting brackets having pivots 64a and 64b extending vertically therefrom.

[0028] Each tensioner 61, 63 further includes arms 68a, 68b having bodies 75a, 75b. The bodies 75a, 75b include first plates 81a, 81b, second plates 82a, 82b, and pivot pins 70a, 70b. Each arm 68a, 68b has a first end 67a, 67b and a second end 69a, 69b on the first plates 81a, 81b and 67b respectively. The first plates 81a, 81b have first holes 83a, 83b at the first ends 67a, 67b and second holes 84a, 84b at the second ends 69a, 69b. The second plates 82a, 82b have first holes 85a, 85b at the first ends 67a, 67b and second holes 86a, 86b at the second ends 69a, 69b. First plates 81a, 81b and second plates 82a, 82b are connected together and aligned by pivot shafts 64a, 64b of mounting brackets 62a, 62b and pivot pins 70a, 70b received in second holes 84a, 84b, 86a, 86b of the first plates 81a, 81b and the second plates 82a, 82b. The distance between the first plates 81a, 81b and the second plates 82a, 82b is equal to at least a portion of the length of the pivot shafts 64a, 64b and the pivot pins 70a, 70b. First holes 83a, 83b, 85a, 85b at the first ends 67a, 67b of the first plates 81a, 81b and the second plates 82a, 82b receive the pivot shafts 64a, 64b and the torsion springs 66a, 66b. Pivot shafts 64a and 64b are surrounded by torsion springs 66a and 66b. The first ends of torsion springs 66a and 66b bias arms 68a and 68b toward chain 8. The second ends of torsion springs 66a and 66b are mounted to mounting brackets 62a and 62b.

[0029] Tensioning feet 72a and 72b are mounted to pivot pins 70a and 70b at the second ends 69a and 69b of the first plates 81a and 81b and the second plates 82a and 82b, and between the first plates 81a and 81b and the second plates 82a and 82b. Tensioning feet 72a and 72b have bodies 87a and 87b, each having pivot point holes 88a and 88b and chain sliding surfaces 74a and 74b. Tensioning feet 72a and 72b receive pivot pins 70a and 70b within the pivot point holes 88a and 88b of the bodies 87a and 87b, wherein the associated pivot point is opposite to the chain sliding surfaces 74a and 74b. In one embodiment, the pivot point holes 88a and 88b are centrally positioned opposite the chain sliding surfaces 74a and 74b that interact with the chain 8.

[0030] In this embodiment, the multi-pivot torsion spring tensioners 61 and 63 have two pivot points, pivot shafts 64a and 64b and pivot pins 70a and 70b, connecting arms 68a and 68b to tensioning feet 72a and 72b. Arms 68a and 68b preferably have a rigid body.

[0031] The first torsion spring tensioner 61 and the second torsion spring tensioner 63 are each fixed to the gearbox 60, which is closer to the driven sprocket 6 than the drive sprocket 2, via mounting brackets 62a and 62b, so that the tension on any segment 8a or 8b of the chain 8 is applied asymmetrically to the driven sprocket 6, thereby allowing the slack of the chain 8 to accumulate near the drive sprocket 2 at the slack position 32.

[0032] The first and second multi-pivot torsion spring tensioners 61 and 63 are provided with:

[0033] • Apply a mechanical preload or force to the minimum slack section of the chain to prevent or force the teeth to jump to the drive sprocket;

[0034] • Minimize the mechanical preload or force in the tensioning section;

[0035] • The tensioner chain sliding surface travels to manage dynamic chain slack and static chain wear for forward and reverse drives; and

[0036] • Restricts the sliding surface of the chain and the movement of the chain during a chain skipping event.

[0037] A stop feature 95 can be added to prevent damage to the tensioner device due to a skip event. During a skip event, the tensioner device can rotate away from chain segments 8a and 8b, where rotation is limited by the interface between the stop feature 95 and the transmission gearbox 60. Figures 5a-5b The image shows a stop feature 95 applied to tensioner feet 72a, 72b; however, the stop feature 95 can also be applied to the tensioner arm or tensioner face. The stop feature 95 creates a "low-stress" contact so as not to damage the tensioner or reduce the tensioner's ability to control chain slack.

[0038] Torsion springs 66a and 66b can be designed with low spring stiffness, thereby applying a smaller force to segments 8a and 8b of chain 8 to achieve a balance between tensioner position and application, thereby minimizing spring force and stiffness to optimize the control and efficiency of chain slack segments 8a and 8b.

[0039] In this embodiment, the arms 68a, 68b of the first and second multi-pivot torsion spring tensioners 61, 63, together with the tensioner feet 72a, 72b, act as constant torque arms during hinge, generating a constant force within the range of motion, thereby optimizing control and system efficiency. Additionally, when the tensioners 61, 63 cover a large hinge angle, packaging can be reduced.

[0040] Figure 6This is a partial view of a transmission gearbox including the torsion spring tensioner of the third embodiment. The transmission gearbox 60 receives a drive sprocket 2, a driven sprocket 6, a chain 8, and a single pivoting torsion spring tensioner 261. The drive sprocket 2 is connected to the driven sprocket 6 via a toothed chain 8. The chain 8 engages with the sprockets 2 and 6, transmitting rotational motion between them.

[0041] The single pivoting torsion spring tensioner 261 has a mounting bracket 262 from which a pivot shaft 264 extends vertically. The pivot shaft 264 receives an arm 268. The arm 268 preferably has a single body 278, but may be manufactured from multiple parts. The arm 268 has a body 278 having a first end 268a, a second end 268b, and a chain sliding surface 274 that interacts with a single chain segment 8a adjacent to the driven sprocket 6. At the first end 268a of the body 278 is a hole 279 for receiving the pivot 264.

[0042] A torsion spring 266 exists between the mounting brackets 262 and acts on the first end 267 of the integral arm 268 pivoting on 264. One end 266a of the spring 266 is grounded relative to the mounting bracket 262, and the second end 266b contacts the arm 268.

[0043] The arrangement of the single pivoting torsion spring tensioner 261, which is mounted closer to the driven sprocket 6 than the drive sprocket 2, results in an asymmetrical tension applied to segment 8a, causing slack in the chain to accumulate near the drive sprocket 2.

[0044] Figure 7 A schematic diagram of a chain system within a transmission gearbox, including a leaf spring tensioner according to the fourth embodiment, is shown.

[0045] The transmission gearbox 60 receives a drive sprocket 2, a driven sprocket 6, a chain 8, a first leaf spring tensioner 361, and a second leaf spring tensioner 363. The drive sprocket 2 is connected to the driven sprocket 6 via the toothed chain 8. The chain 8 meshes with sprockets 2 and 6, transmitting rotational motion between them.

[0046] The first and second leaf spring tensioners 361 and 363 each have mounting brackets 362a and 362b and mounting surfaces 375a and 375b, respectively. The mounting brackets 362a and 362b have pivot shafts 364a and 364b extending vertically from them. The pivot shafts 364a and 364b pivotally receive first ends 367a and 367b of the resilient leaf spring tensioner arm bodies 368a and 368b via pivot holes 381a and 381b. The second ends 369a and 369b of the resilient leaf spring tensioner arm bodies 368a and 368b are adjacent to and interact with the mounting surfaces 375a and 375b. The resilient leaf spring tensioner arm bodies 368a and 368b have chain sliding surfaces 374a and 374b, which have the outline of a new chain path that interacts with chain segments 8a and 8b of the chain 8. Opposite to the chain sliding surfaces 374a, 374b are means for receiving and accommodating at least the ends of leaf springs 366a, 366b. Leaf springs 366a, 366b may be accommodated by recesses formed by the tensioner arm bodies 368a, 368b of the tensioner, tabs, or other means for securing at least these ends of leaf springs 366a, 366b to the tensioner body 368a. 368b allows leaf springs 366a, 366b to bend. The elastic leaf tensioner arm bodies 368a, 368b and leaf springs 366a, 366b can flex and bend outwards and away from the mounting surfaces 375a, 375b.

[0047] The first and second leaf spring tensioners 361 and 363 are respectively fixed to the gearbox 160, which is closer to the driven sprocket 6 than the drive sprocket 2, by mounting brackets 362a and 362b, so that the tension on any segment 8a or 8b of the chain 8 is applied asymmetrically to the driven sprocket 6, thereby allowing the slack of the chain 8 to accumulate in the vicinity of the drive sprocket 2.

[0048] Figure 8 A schematic diagram of a chain system with a two-stage tensioner is shown.

[0049] The transmission gearbox receives a drive sprocket 2, a driven sprocket 6, a chain 8, a first tensioner 461, and a second tensioner 463. The drive sprocket 2 is connected to the driven sprocket 6 via a toothed chain 8. The chain 8 meshes with sprockets 2 and 6, transmitting rotational motion between them.

[0050] In this embodiment, the first tensioner 461 and the second tensioner 463 act on chain segments 8a and 8b adjacent to the driven sprocket 6. The first tensioner 461 and the second tensioner 463 are mechanically connected together 480 such that rotation of the first tensioner 461 toward segment 8a of the chain 8 causes the second leaf spring tensioner 463 to pivot away from the opposite chain segment 8b.

[0051] The first and second tensioners 461 and 463 are each mounted closer to the driven sprocket 6 than the drive sprocket 2, such that the tension on either segment 8a or 8b of the chain 8 is applied asymmetrically toward the driven sprocket 6, thereby allowing slack in the chain 8 to accumulate in the vicinity of the drive sprocket 2.

[0052] Although not shown, in alternative embodiments, the first tensioning device may be a different device from the second tensioning device. In one example, the first tensioning device is a first multi-pivot torsion spring 61, and the second tensioning device is a second leaf spring tensioner 363. This example is not limiting, and other combinations are possible.

[0053] Therefore, it should be understood that the embodiments of the invention described herein are merely illustrative of the application of the principles of the invention. Reference to the details of the illustrated embodiments herein is not intended to limit the scope of the claims, which themselves state those features considered essential to the invention.

Claims

1. A chain system within the transmission gearbox of an engine, comprising: Drive sprocket; Driven sprocket; A chain that connects the drive sprocket to the driven sprocket, the chain having a slack section between the driven sprocket and the drive sprocket and a tension section between the driven sprocket and the drive sprocket; A first tensioner is installed in the transmission gearbox to interact with the slack section of the chain at a first mounting position closer to the driven sprocket than the drive sprocket, thereby applying tension asymmetrically toward the driven sprocket, causing the slack of the chain to accumulate near the drive sprocket, thereby increasing the chain's jump torque. as well as A second tensioner is mounted within the transmission gearbox to interact with the tensioned section of the chain at a second mounting position closer to the driven sprocket than the drive sprocket. The first tensioner and the second tensioner each include: Mounting bracket, which is mounted to the transmission gearbox, the mounting bracket having a pivot shaft extending vertically therefrom; The body includes an arm comprising: A first plate, which defines a first hole at a first end for receiving the pivot shaft and a second hole at a second end; The second plate defines a first hole at a first end for receiving the pivot shaft and a second hole at a second end; A pivot pin is received in the second hole of the first plate and the second hole of the second plate; A tensioning foot, received between the first plate and the second plate, the tensioning foot comprising a body defining a pivot hole for receiving the pivot pin and having a chain sliding surface adapted to interact with a slack section of the chain, the pivot hole opposite the chain sliding surface; and A torsion spring, which is mounted between the mounting bracket and the arm, biases the first end of the arm on the pivot shaft toward the slack section of the chain.

2. The chain system of claim 1, wherein the first end of the torsion spring is grounded to the mounting bracket, and the second end of the torsion spring contacts the first end of the arm.

3. The chain system of claim 1, wherein the first tensioner and the second tensioner are mechanically connected together.

4. The chain system of claim 1, further comprising a stop mounted on each of the tensioning feet, the stop being adapted to prevent damage to the tensioner device due to a skip event by limiting rotation of the tensioning foot through the interface between the drivetrain gearbox and the stop.

5. The chain system of claim 1, wherein the chain has a width between 12.70 mm and 50.8 mm.

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