Dual arm tensioner with dynamic pivot

Abstract

In order to achieve optimal performance and belt life, it is important to properly tension the belt. In some cases, such as in a hybrid vehicle, belt starter generator (BSG) parameters are varied due to reclamation or the like, and the belt is greatly varied in terms of drive torque, and the dynamic pivot may optimize belt tension for various engine modes. In some embodiments, a dynamic pivot dual arm tensioner may include: a center arm having a first tension pulley journaled to the center arm and engageable with a mounting surface, such as an engine block or accessory bracket, through a mounting shaft; a side arm having a second tension pulley journaled to the side arm and coupled to the center arm; a dynamic pivot, wherein the tensioner is dynamically rotated around the dynamic pivot; and the dynamic pivot journal is connected to the central arm.

Description

[0001] This application claims the priority of U.S. Provisional Patent Application No. 63 / 408,248, filed on September 20, 2022, the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present invention relates to a dynamic pivot double - arm belt tensioner for hybrid drive systems and conventional drive systems. BACKGROUND OF THE INVENTION

[0003] The present disclosure relates to belt tensioners, such as for hybrid vehicles, and other systems that use double - arm tensioners, such as in the conventional automotive and transportation industries. Applications that use belts typically require the use of a belt tensioner to ensure the desired performance. Double - arm tensioners may have significant advantages over single tensioners because they can reduce hub loads and can provide better control over belt slippage. Modern engines with starter - generator units have been developed to improve fuel consumption and emissions.

[0004] The tensioners of the present disclosure are particularly suitable for optimizing belt tension in different engine modes, increasing belt life, reducing noise generation, and increasing overall system efficiency. Double - arm tensioners can include a dynamic pivot to help achieve this. Incorporating a dynamic pivot may be beneficial for providing optimal belt tension in different engine modes, such as but not limited to belt - starter - generator (BSG) start, recovery, power generation, shutdown, braking, supercharging, etc. As the complexity of hybrid motors and conventional motors increases, the complexity of the new generation of double - arm tensioners also increases. With the increase in complexity and the number of parts, it may initially be difficult to find a good position for the central arm pivot of the tensioner in at least one of several engine modes available in current automotive applications without causing one of the arm or pulley to collide with other accessories or resulting in problems such as but not limited to a smaller and non - optimal wrap angle around the pulley, a higher degree of vibration of the belt section, belt slippage, and / or low belt tension. Currently, the solution to these problems is to find a position through testing, however, no single engine mode is optimal at that position, which means sacrificing performance. The present invention integrates eccentricity into the axis of rotation of the central arm of the tensioner by utilizing a dynamic pivot, which can achieve optimal belt tension in a variety of different engine modes.

[0005] Generally, engines with starter - generator units have been developed to improve the fuel consumption and emissions of modern vehicles. When the starter - generator unit in this type of engine is activated, it acts as a starter motor to restart the engine. Once the engine is started, the starter - generator unit can be used as a generator to recharge the battery.

[0006] The starter - generator unit is mechanically connected to the crankshaft of the engine by a loop drive device such as a belt or a chain. The loop drive device vibrates under the influence of the system, especially when the starter - generator unit switches functions between the starter and the generator. In this case, the tension side and the slack side of the loop drive device exchange roles. For this reason, the industry has developed a tensioner to handle the vibration of the loop drive device with a starter - generator unit.

[0007] For a specific tensioner, refer to the tensioner structures disclosed in US7637829, US9341243, US9651122, EP2384272B1, WO2021 / 093836, etc. and incorporated herein by reference. SUMMARY OF THE INVENTION

[0008] In one embodiment of a dynamic pivot double - arm tensioner, there may be a bushing with variable thickness such that two pivot centers exist within the same bushing. One of the pivot centers may be the center of the inner diameter of the bushing. In some embodiments, it may be beneficial for this pivot center to be stationary or fixed. In another embodiment, the second pivot center may be the center of the outer diameter of the bushing. In some embodiments, it may be beneficial for the second pivot center to be dynamic, depending on the hub load angle applied to the pulley generated by different belt loads. In some embodiments, the dynamic pivot may have different positions for each different engine mode. This may be because the hub load angle varies according to the torque generated or used by the BSG.

[0009] In certain embodiments, it may be beneficial to utilize two pivot centers (a fixed pivot and a dynamic pivot) because after finding the ideal position of the tensioner pivot for each engine mode, the eccentricity level of the bushing and the necessary layout of the double - arm tensioner can be determined more optimally. This optimization may include but is not limited to moving the dynamic pivot closer to the ideal tensioner position for each engine mode, or precisely positioning the dynamic pivot at those ideal positions for each torque level of the BSG.

[0010] In some embodiments, optimizing the position of the dynamic pivot may be beneficial for maximizing the wrap angle, minimizing belt slip on the pulley, minimizing belt vibration, minimizing the variation of belt tension, and minimizing the variation of pulley hub load under different engine modes. By optimizing these parameters, the durability and lifespan of the belt, pulley, and tensioner damping elements can be improved. In some embodiments, the performance of the vehicle can also be improved.

[0011] For a specific pulley layout for each engine mode, there is an ideal position for locating the pivot of the tensioner. In some embodiments, the ideal position can be a position where the wrap angle around the pulley is maximized and belt slip, belt vibration, belt tension variation, and hub load variation are minimized. In some embodiments, the center arm of the tensioner can rotate around a dynamic pivot rather than pivot around a fixed pivot in current prior art double-arm tensioners.

[0012] Some beneficial effects of the present invention may be that the double-arm tensioner has a simple structure and is easy to assemble, while also being able to provide optimal belt tension for different engine modes.

[0013] Additionally or alternatively, the tensioner can have at least two arms that can rotate dynamically around a dynamic pivot. The dynamic pivot can include but is not limited to: a center arm with a journal connected to a first tension pulley; a side arm with a journal connected to a second tension pulley, the side arm being coupled to the center arm; and the center arm can pivot around the dynamic pivot. Other embodiments are also described and recited herein.

[0014] The present invention content is provided to introduce in a simplified form a selection of some concepts that will be further described below in the detailed description. The present invention content is not intended to identify the key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 An exemplary isometric view of a dynamic pivot double-arm tensioner.

[0016] Figure 2 An exemplary top view of a dynamic pivot double-arm tensioner.

[0017] Figure 3 An exemplary cross-sectional view of a dynamic pivot double-arm tensioner along plane A-A.

[0018] Figure 4 An exemplary embodiment for a first engine mode.

[0019] Figure 5 An exemplary embodiment for a second engine mode.

[0020] Figure 6 An exemplary embodiment for a third engine mode.

[0021] Figure 7 An exemplary embodiment for a fourth engine mode. DETAILED DESCRIPTION

[0022] As described above, what is described herein is a two-armed belt tensioner that utilizes a dynamic pivot and is configured to optimize the dynamics of a belt and pulleys at different engine mode torques.

[0023] In the following description, reference is made to the accompanying drawings, which form a part of the following description and in which at least one specific embodiment is shown by way of illustration. The following description provides additional specific embodiments. It should be understood that other embodiments may be envisioned and constituted without departing from the scope or spirit of the present disclosure. Accordingly, the following detailed description should not be considered restrictive. Although the present disclosure is not limited thereto, an understanding of the various aspects of the present disclosure will be obtained through a discussion of the examples provided below, including the accompanying drawings. In some cases, reference numerals may have associated sub-labels consisting of lowercase letters to denote one of a plurality of similar components. When a reference numeral is mentioned without specifying a sub-label, the reference is intended to refer to all such similar components.

[0024] Figure 1 Exemplary illustration of a dynamic pivot two-armed tensioner. Figure 1 A dynamic pivot two-armed tensioner 100 according to the present disclosure is shown. In some embodiments, the dynamic pivot two-armed tensioner 100 may include, but is not limited to: a center arm 102 journaled to the center of a first tension pulley 106; a side arm 104 journaled to a second tension pulley 108, the side arm being coupled to the center arm; the center arm being pivotable about a dynamic pivot 110; and a carrier member 124 that houses a side arm tension member. In some embodiments, the center arm 102 may be made of stamped metal, engineering grade polymer, composite material, or similar materials. The center arm 102 may be manufactured by stamping, machining, casting, or by a combination of multiple processes. In some embodiments, the side arm 104 may be made of stamped metal, engineering grade polymer, composite material, or similar materials. The side arm 104 may be manufactured by stamping, machining, casting, a combination of multiple processes, etc. In the foregoing embodiments, reference Figure 1, the central arm 102 is disposed on the left side of the motor generator unit, and the side arm 104 is disposed on its right side. In other embodiments, the central arm 102 may be disposed on the right side of the motor generator unit, and the side arm 104 may be disposed on its left side, that is, the left and right positions of the central arm and the side arm may be interchanged. In some embodiments, the side arm 104 may be coupled to the central arm 102 by using a fixing member, such as but not limited to a fastener, a snap fitting, or the like. In some embodiments, a torsion spring may be axially disposed around the fastener or fastening member between the side arm 104 and the central arm 102. In some embodiments, the side arm 104 may include a load-bearing member 124 having a friction surface that engages the surface on the central arm 102 and having a friction surface that engages the side arm 104 to damp the oscillatory movement of the side arm. In some embodiments, the central arm may pivot dynamically about a dynamic pivot. The dynamic pivot 110 may be an eccentric bearing that allows the hub loads of different engine modes to be in an optimal position.

[0025] Generally, one or more accessory pulleys may be provided between the crankshaft pulley and the motor generator unit pulley as needed. When the accessory pulley is provided, the first and second transmission members may be the crossover portions between the motor generator unit pulley and the accessory pulley, respectively. The first transmission member is on the left side of the motor generator unit pulley, and the second transmission member is on the right side of the motor generator unit pulley. In some embodiments, the dynamic pivot double-arm tensioner 100 may include an arcuate central arm to allow the dynamic pivot double-arm tensioner 100 not to interfere with the motor generator pulley or another accessory pulley.

[0026] In one embodiment, the central arm 102 is provided with a dynamic pivot central hole 111 passing through the dynamic pivot 110, and the side arm 104 is pivotally fixed to the internal combustion engine and the dynamic pivot double-arm tensioner 100 by using a fixing member (not shown in the figure), and the fixing member is configured to fix the dynamic pivot double-arm tensioner 100 to the engine block or other mounting surfaces. The fixing member may be in various forms. For example, the fixing member may be provided as a bolt, a pin, or a snap fastener. In some embodiments, an antifriction member, such as a lining or a bearing having a low coefficient of friction, may be provided between the fixing member and the dynamic pivot central hole (shown as 211 in Figure 2 to allow the side arm 104 of the dynamic pivot double-arm tensioner 100 to pivot freely on the internal combustion engine. Additionally, the antifriction member may provide a certain degree of damping to reduce the relative movement between the central arm and the fixing member.

[0027] In some embodiments of the dynamic pivot double - arm tensioner 100, it may be beneficial to include the following components: a center arm having a first tension pulley 106 journal - connected to the center arm 102 and engageable with a mounting surface (such as an engine block or an accessory bracket) via a mounting shaft; a side arm 104 having a second tension pulley 108 journal - connected to the side arm 104 and coupled to the center arm 102 by using pins, snap - fit fittings, bolts, tension members, or the like; a dynamic pivot 110 about which the dynamic pivot double - arm tensioner 100 rotates dynamically; and the dynamic pivot 110 is journal - connected to the center arm 102. In some embodiments, the first and second tension pulleys 106, 108 may be made of metal alloy, polymer, composite material, or similar materials.

[0028] In some embodiments, the dynamic pivot 110 may include an eccentric bushing that may permit at least two variable and / or dynamic pivot centers. In some embodiments, to help achieve proper belt tension, a torsion spring may be displaced between the side arm 104 and the center arm 102. In some embodiments, the torsion spring may be encapsulated in a carrier member 124 that may also include a friction surface that engages a surface on the center arm and has a frictional engagement with the side arm to damp the oscillatory movement of the side arm. A damping member may also be included, and the damping member may be an engineered polymer, a polymer or composite pad, a slipper pad, or the like.

[0029] In some embodiments, it may be beneficial to further include a fixing member for reliably fixing the dynamic pivot double - arm tensioner 100 to a motor - generator, an engine block, an accessory bracket, or the like. The fixing member may be a bolt configured and arranged to pass through a dynamic pivot center hole aligned with the mounting shaft of the dynamic pivot 110 to fix the dynamic pivot double - arm tensioner 100 to the motor - generator. The fixing member may also be a pin, a snap - fit member, or the like.

[0030] In another embodiment of the dynamic pivot double - arm tensioner 100, it may be beneficial to include the following components: a center arm having a first tension pulley journal - connected to the center arm and engageable with a mounting surface (such as an engine block or an accessory bracket) via a mounting shaft; a side arm 104 having a second tension pulley 108 journal - connected to the side arm 104 and coupled to the center arm 102 by using pins, snap - fit fittings, bolts, tension members, or the like; a dynamic pivot about which the tensioner rotates dynamically, wherein the dynamic pivot 110 is an eccentric bushing; and the dynamic pivot is journal - connected to the center arm.

[0031] In some embodiments, the dynamic pivot 110 may include an eccentric bushing that may permit at least two variable and / or dynamic pivot centers. In some embodiments, to help achieve proper belt tension, a torsion spring may be displaced between the side arm and the center arm. In some embodiments, the torsion spring may be encapsulated within a carrier member 124 that may also include a friction surface that engages a surface on the center arm 102 and has a frictional engagement with the side arm to damp the oscillatory movement of the side arm. A damping member may also be included, which may be an engineered polymer or composite pad, slipper, or the like.

[0032] In some embodiments, it may be beneficial to further include a securing member for securely attaching the dynamic pivot double arm tensioner 100 to a motor generator, engine block, accessory bracket, or the like. The securing member may be a bolt configured and arranged to pass through a dynamic pivot center hole aligned with the mounting axis of the dynamic pivot 110 to attach the dynamic pivot double arm tensioner to the motor generator. The securing member may also be a pin, snap member, or the like.

[0033] Figure 2 Exemplary top view of a dynamic pivot double arm tensioner. In some embodiments, the dynamic pivot double arm tensioner 200 may include, but is not limited to, a center arm 202 journaled to a first idler pulley 206, and a side arm 204 journaled to a second idler pulley 208, the side arm being coupled to the center arm, and the center arm being pivotable about a dynamic pivot 210. In some embodiments, the dynamic pivot may include an eccentric bushing 212 having a dynamic pivot center hole 211 that permits different levels of eccentricity depending on the geometry of the bushing. The dynamic pivot center hole 211 may also permit the dynamic pivot double arm tensioner 200 to be attached to an engine block, accessory bracket, or motor generator by a securing member such as a bolt, pin, or snap member. In some embodiments, the snap member may be a pawl in the geometry of the center arm that permits the dynamic pivot double arm tensioner 200 to be removably locked to an engine block, accessory bracket, or motor generator. The snap member may also be a locking clip, locking tab, or the like.

[0034] Figure 3Exemplary cross-sectional view along plane A-A of a dynamic pivot double-arm tensioner. In some embodiments, the center of the axis of rotation A of the double-arm tensioner has been eccentrically displaced by a distance "X" from the axis of rotation B of the dynamic pivot. When the dynamic pivot double-arm tensioner 300 pivots about axis A, the distance "X" determines the level of eccentricity. The dynamic pivot center hole 211 is aligned with axis A. In some embodiments, the dynamic pivot double-arm tensioner 300 may include a center arm 302, a dynamic pivot 310, a second idler pulley 308, a damping member 320 that may be a friction-reducing member damping mechanism, side arms 304, and a tension member 322. In some embodiments, the damping member 320 may also be disposed between the load-bearing member 324 and the side arm 304 so that the side arm 304 better biases the dynamic pivot 310 and reduces the vibration of the dynamic pivot 310. Typically, the damping member 320 may abut the end portion of the tension member 322 that may be a torsion spring and be connected in series; or the damping member 320 may be connected in parallel with the torsion spring. Of course, other forms may also be used.

[0035] In some embodiments, a disc spring (not shown) may also be provided on the dynamic pivot center around the dynamic pivot center hole. The disc spring may be axially disposed between the fixed member and the center arm, thereby providing axial pressure to the dynamic pivot center and increasing the damping of the dynamic pivot center around the dynamic pivot center hole.

[0036] Figure 4 Exemplary embodiment of a first engine mode. In one embodiment, the first engine mode may be an engine mode such as, but not limited to, starting, belt starter generator (BSG) starting, recovery, power generation, shutdown, braking, supercharging, etc. Each mode may have an ideal tensioner position. In one embodiment, it may be beneficial to place the position of the fixed pivot (the center of the inner diameter of the bushing) at the approximate intersection of the resulting hub loads of two desired engine modes to be optimized (or at the exact intersection if each intersects at an exact point). For engine modes to be optimized using a single component, it may be necessary to make the intersection of the resulting hub loads intersect the symmetry line. The symmetry line may be an imaginary line that is perpendicular to the line connecting the most extreme ideal tensioner positions. Multiple engine modes may be used to calculate the ideal tensioner position. Based on the hub loads generated by the belt drive system, the eccentricity level used to optimize the dynamic pivot can be calculated.

[0037] In one embodiment, when calculating the eccentricity required for a specific dynamic pivot for a specific application, the resulting hub loads may point to their corresponding ideal positions. In this embodiment, the angles between the resulting hub loads are relatively large, which may result in a relatively low required eccentricity level. In this embodiment, the resulting hub loads are equal and at equal angles to the symmetry line, thus resulting in the same eccentricity level for each engine mode.

[0038] Figure 5 An exemplary embodiment for a second engine mode. In another embodiment, the second engine mode can be an engine mode such as, but not limited to, starting, belt starter generator (BSG) starting, recuperation, power generation, shutdown, braking, supercharging, etc. Each mode can have an ideal tensioner position. In some embodiments, depending on the resulting hub loads, the resulting hub loads may still point to their corresponding ideal positions, but the angles between the hub loads may be smaller, resulting in an even lower eccentricity level. However, in this embodiment, the resulting hub loads are not equal with respect to the symmetry line, and thus it may not be possible to obtain the ideal eccentricity level for each engine mode. In this embodiment, each engine mode requires a different eccentricity level. In such a case, the best solution is to move the position of the double-arm tensioner so that the resulting hub loads and angles are closer to being equal, so that the eccentricity levels are closer to being equal.

[0039] Figure 6 An exemplary embodiment for a third engine mode. In another embodiment (not an ideal case), the resulting hub loads may not intersect. The resulting hub load vectors still point to their ideal positions, but the angles between the resulting hub loads are too small, which results in a relatively large eccentricity level, and the tensioner packaging requirements may not be able to achieve such an eccentricity level. However, if there are no packaging limitations, such as for large industrial motors, a large dynamic pivot may be able to achieve a relatively large eccentricity level.

[0040] Figure 7 An exemplary embodiment for a fourth engine mode. In another embodiment, the angles between the resulting hub loads are relatively large, which results in a relatively low eccentricity level. The resulting hub load vectors may also be symmetric with respect to the symmetry line, which is an ideal situation for having equal eccentricity levels for each different engine mode. However, as Figure 7 shown, the resulting hub load vectors do not point to the corresponding ideal positions of each one, which may result in a mismatch between the ideal positions and the positions of the dynamic pivots in each engine mode. In such a case, it may be most beneficial to modify the layout of the tensioner system and the belt layout so that the resulting hub loads move within their ideal positions.

[0041] The foregoing description and examples provide a complete description of the structure and use of exemplary embodiments of the present invention. The above description provides specific embodiments. It should be understood that other embodiments may be conceived and constituted without departing from the scope or spirit of the present disclosure. Accordingly, the foregoing detailed description should not be considered restrictive. For example, elements or features of one example, embodiment, or implementation may be applied to any other example, embodiment, or implementation described herein to the extent that such content does not conflict. Although the present disclosure is not limited thereto, an understanding of various aspects of the present disclosure will be obtained through the discussion of the examples provided.

[0042] Unless otherwise indicated, all numbers expressing feature sizes, amounts, and physical properties should be understood to be modified by the term "about," whether or not the term "about" is directly present. Accordingly, unless indicated to the contrary, the numerical parameters set forth are approximations that may vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings disclosed herein.

[0043] As used herein, the singular forms "a" and "the" encompass embodiments having plural referents, unless the content clearly indicates otherwise. As used in this specification and the appended claims, the term "or" is generally employed in its sense including "and / or," unless the content clearly indicates otherwise.

[0044] Although the technology has been described in language specific to certain structures and materials, it should be understood that the invention as defined in the appended claims is not necessarily limited to the specific structures and materials described. Rather, the specific aspects are described as forms of implementing the claimed invention. Since many embodiments of the invention may be practiced without departing from the spirit and scope of the invention, the invention resides in the appended claims below.

Claims

1. A tensioner, comprising: a central arm having a first tension pulley journaled to the central arm and engageable with a mounting surface through a mounting shaft; a side arm having a second tension pulley journaled to the side arm and coupled to the central arm; a dynamic pivot about which the tensioner rotates dynamically; and the dynamic pivot being journaled to the central arm.

2. The tensioner according to claim 1, wherein, the dynamic pivot includes an eccentric bushing.

3. The tensioner according to claim 1, further comprising a torsion spring disposed between the side arm and the central arm.

4. The tensioner according to claim 3, further comprising: a load-bearing member having a friction surface engaging a surface on the central arm and having a friction surface engaging the side arm to dampen oscillatory movement of the side arm.

5. The tensioner according to claim 1, wherein, the central arm is stamped.

6. The tensioner according to claim 1, wherein, the central arm is cast.

7. The tensioner according to claim 1, wherein, the side arm is stamped.

8. The tensioner according to claim 1, wherein, the side arm is cast.

9. The tensioner according to claim 1, further comprising a fixing member.

10. The tensioner according to claim 9, wherein, the fixing member includes a bolt configured and arranged to pass through a central hole of the dynamic pivot aligned with the mounting shaft of the dynamic pivot to fix the tensioner to the motor generator.

11. A tensioner, comprising: a central arm having a first tension pulley journaled to the central arm and engageable with a mounting surface through a mounting shaft; a side arm having a second tension pulley journaled to the side arm and coupled to the central arm; a dynamic pivot about which the tensioner rotates dynamically, wherein the dynamic pivot includes an eccentric bushing; and the dynamic pivot being journaled to the central arm.

12. The tensioner according to claim 11, further comprising a torsion spring disposed between the side arm and the central arm.

13. The tensioner according to claim 12, further comprising: a load-bearing member having a friction surface engaging a surface on the central arm and having a friction surface engaging the side arm to dampen oscillatory movement of the side arm.

14. The tensioner according to claim 11, wherein, the central arm is stamped.

15. The tensioner according to claim 11, wherein, the central arm is cast.

16. The tensioner according to claim 11, wherein, the side arm is stamped.

17. The tensioner according to claim 11, wherein, the side arm is cast.

18. The tensioner according to claim 11, further comprising a fixing member.

19. The tensioner according to claim 18, wherein, The fixed member includes a bolt that is configured and arranged to pass through a dynamic pivot center hole that is aligned with the mounting shaft of the dynamic pivot to fix the tensioner to the motor generator.

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