High bias belt tensioner with torsion spring force balance

Abstract

A high bias belt tensioner includes a base having a pivot tube defining a first axis of rotation, an arm having a pivot tube receiver rotatably disposed on the pivot tube, the arm having a pulley pivot tube defining a second axis of rotation. A torsion spring is disposed on an outer surface of the pivot tube receiver, a first spring end attached to the base, a second spring end oriented and housed within the pulley pivot tube. A pulley is disposed on the pulley pivot tube and rotatable thereabout. A dust cover is disposed on the pulley pivot tube and adjacent the pulley, a first end of the pivot tube deformed toward the dust cover to secure the pulley without the use of a pulley bolt.

Description

[0001] Cross-reference to related applications This patent application claims priority to U.S. Provisional Application No. 63 / 614,984, filed December 27, 2023, the entire disclosure of which is incorporated herein by reference. Technical Field

[0002] The present invention relates generally to a high-bias belt tensioner, and more specifically to a high-bias belt tensioner in which a torsion spring is operably engaged with a tensioner arm via a spring end foot housed within a pulley pivot tube, the pulley shaft being connected to the pulley pivot tube. Background Technology

[0003] There is a need for an improved Z-belt tensioner design in which the hub load force can be balanced by the torsional spring force, and which uses a structurally robust spring with fewer parts. Summary of the Invention

[0004] In various respects, the high-bias belt tensioner described herein includes: a base having a pivot tube defining a first axis of rotation; an arm having an arm sleeve rotatably fitted onto the pivot tube, and the arm having a pulley pivot tube defining a second axis of rotation; a torsion spring fitted onto the outer surface of the arm sleeve, a first spring end of which is attached to the base, and a second spring end oriented and accommodated within the pulley pivot tube; a pulley disposed on and rotatable about the pulley pivot tube; and a dust cover disposed on and adjacent to the pulley on the pulley pivot tube; wherein a first end of the pivot tube is deformed toward the dust cover to secure the pulley without the use of pulley bolts.

[0005] The first end of the pulley pivot tube defines a socket opposite the second spring end, configured to receive a tool. The socket may have multiple toothed receiving structures. The second end of the pulley pivot tube has an annular hole including an axial flange extending inward toward the first end of the pivot tube.

[0006] The arm bushing defines an opening. The tensioner also includes a bushing housed within the arm bushing and located between the pivot tube and the inner surface of the arm bushing. The bushing has a lug extending out of the opening, the lug engaging with a coil of the torsion spring. The bushing includes an axial slit opposite the lug. When the torsion spring is wound around the outer surface of the arm, the bushing can be compressed against the pivot tube to dampen the movement of the arm.

[0007] The high-bias tensioner also includes an arm plate housed within a shouldered recess of the arm bushing and engaging with a first end of the pivot tube. The arm plate surrounds the bushing inside the arm. The arm plate provides a rigid surface for rotational contact between the arm and the bushing. The bushing has multiple grooves on a first surface facing the pivot tube and a second surface facing the arm plate for receiving grease.

[0008] The base of the tensioner has an arc-shaped protrusion that engages with an arc-shaped track on the pivot tube housing of the arm. The arc-shaped track limits the rotation angle of the arm about the first axis of rotation. The base has a locating pin that extends from the mounting surface of the base and is positioned opposite the spring abutment structure of the base.

[0009] The torsion spring can be an exposed torsion spring or a closed torsion spring.

[0010] On the other hand, the high-bias belt tensioner includes: a base having a pivot tube defining a first axis of rotation; an arm having an arm sleeve rotatably fitted onto the pivot tube, and the arm having a pulley pivot tube defining a second axis of rotation; a torsion spring fitted onto the outer surface of the arm sleeve, a first spring end of which is attached to the base, and a second spring end oriented and accommodated within the pulley pivot tube; a pulley having a rolling bearing rotatably mounted on the pulley pivot; a dust cover disposed on the rolling bearing; wherein the pulley pivot tube partially extends through the rolling bearing, and the second spring end of the torsion spring extends through the pulley pivot tube, the rolling bearing, and extends beyond the pulley; and a nut disposed on the second spring end of the torsion spring and engaging with the dust cover, and the nut defining a protrusion configured to receive a tool.

[0011] In one embodiment, the second spring end of the torsion spring is threaded, and the nut has a matching thread. In other embodiments, the second spring end of the torsion spring and the nut are fixed together by brazing, laser welding, or adhesive. Attached Figure Description

[0012] To better understand the present invention, preferred embodiments are described below by way of non-limiting examples with reference to the accompanying drawings, which are as follows: Figure 1 A side perspective view of a first embodiment of a high-bias belt tensioner; Figure 2 This is a top view of the first embodiment; Figure 3 For along Figure 2 Longitudinal sectional view of line AA in the middle; Figure 4 This is an exploded perspective view of the first embodiment; Figure 5 This is a side perspective view of the arm in the first embodiment; Figure 6 This is a bottom-view plan view of the arm; Figure 7 This is a side perspective view of the base of the first embodiment; Figure 8 A bottom-view perspective of the base; Figure 9 A side perspective view of a second embodiment of a high-bias belt tensioner; Figure 10 This is a longitudinal sectional view of the second embodiment. Detailed Implementation

[0013] The following detailed description will illustrate the general principles of the invention, and examples of the invention will be further explained with reference to the accompanying drawings. In the drawings, the same reference numerals denote the same or similar functional elements.

[0014] Reference Figures 1 to 4 This example illustrates a first embodiment of a high-bias belt tensioner 100, used to provide tension to annular belts in belt-driven systems (e.g., drive belt systems) commonly found in engine systems. High-bias belt tensioners are also known as Z-type belt tensioners. Figure 3 As indicated by the label, in a high-bias belt tensioner, the plane perpendicular to the pulley rotation axis (B) and containing the hub load force (arrow X) is axially higher than the plane containing the torsion spring reaction force (arrow Y) in the tensioner body 100. The tensioner 100 includes a support base 102 with a pivot tube 103 defining a first rotation axis (A); an arm 104 having a pivot tube housing 105 (also called an arm sleeve), the pivot tube housing 105 being rotatably fitted onto the pivot tube 103, and the arm 104 having a pulley pivot tube 107 defining the pulley rotation axis (B). A torsion spring 108 is fitted onto the outer surface 109 of the arm sleeve 105, its first spring end 110 attached to the base 102, and its second spring end 112 oriented and housed within the pulley pivot tube 107. Figure 3 As best seen, the second spring end 112 is oriented upward along the axis of rotation B. A pulley 114 is mounted on and rotatable about the pulley pivot tube 107. A dust cover 120 is mounted on the pulley, and more specifically, on the rolling bearing 116. Figure 3The assembly state prior to the final manufacturing step, which involves deforming the first end 170 of the pulley pivot tube 107 toward the dust cover 120 (e.g., by radial riveting or spinning) to secure the pulley 114 without using pulley bolts.

[0015] The pulley 114 is preferably axially connected to the pulley pivot tube 107 via a rolling bearing 116. The rolling bearing 116 is in... Figure 3 As can be seen in the cross-sectional view, the pulley 114 has a belt engagement surface 117. In the drawings, the belt engagement surface is shown as a plane, but is not limited thereto. The belt engagement surface may be textured or provided with ribs, such as V-ribs or teeth, for engagement with a belt. The pulley may be made of any suitable material, including metal, plastic, or composites thereof. The dust cover 120 is coaxially mounted on the pulley pivot tube 107 to surround the rolling bearing and secure the pulley 114. To seal the bottom of the pulley 114 to prevent the ingress of debris and contaminants, an annular seal (not shown), such as a V-ring, X-ring, or O-ring seal, may be provided in a manner that operably engages with the annular shoulder 123 of the arm 104, from which the pulley pivot tube 107 extends.

[0016] Reference Figures 1 to 4 The torsion spring 108 applies a torsional spring force to the arm 104 in the direction toward the belt (i.e., the belt engagement direction), causing the pulley 114 to apply a corresponding tension force to the belt. Here, the torsion spring 108 is a helical spring, such as a round wire helical spring. The helical spring is an exposed spring—there is no spring housing surrounding the torsion spring 108. This reduces the cost of the tensioner. As described above, the second spring end 112 of the torsion spring 108 is oriented and housed within the pulley pivot tube 107, which allows the torsion spring 108 to move with the arm and counteract the hub load force throughout the entire swing range of the arm. Because the second spring end 112 is housed within the pulley pivot tube 107, the resultant force acting back to the base pivot tube 103 is zero. Figure 3 As indicated by the label, the spring reaction force Y radially inward presses against the damping lug 132 extending from the opening 122 on the arm bushing 105 of the arm 104, and transmits this force to the spring abutment structure 150 of the base 102, i.e., through this part to the mounting base. One advantage of this is that the amount of material used in the arm 104 can be reduced, because the torsion spring 108 transmits the load back to the pivot tube 103.

[0017] The tensioner 100 also includes a bushing 130, which is housed within the arm bushing 105 and located between the pivot tube 103 and the inner surface 113 of the arm bushing 105. The bushing 130 includes a damping lug 132 that extends through the opening 122 of the arm and actively engages with the coil of the torsion spring 108 (see [link to relevant documentation]). Figure 3 The damping lug 132 is designed to extend through the arm bushing 105, so that when the spring is coiled (outer diameter decreases), the spring can act on the damping lug 132. Figure 4 As best seen in the image, the bushing 130 includes a cylindrical body 138 having a first open end and a second open end; and an annular flange 139 extending radially outward from the first open end. A damping lug 132 protrudes outward from the cylindrical body 138 and is shaped to be received in a window 122 of the arm bushing 105. Through the engagement of the damping lug 132 and the window 122, the bushing 130 can rotate with the arm 104. The cylindrical body 138 includes an axially arranged slit 136 that penetrates the cylindrical body 138 and the annular flange 139, extending from the first open end to the second open end. The slit 136 is generally positioned opposite the damping lug 132.

[0018] During the operation of the belt tensioner 100, when the torsion spring winds around the arm bushing 105, the damping lug 132 is subjected to radially inward pressure, thereby compressing the bushing cylinder 138 against the pivot tube 103 and generating frictional engagement to dampen the movement of the arm. When the annular power transmission element is tensioned at the side of the tensioner, the belt load or other forces will cause the spring to wind up, at which point the structure provides positional frictional damping for the movement of the arm 104. The winding direction of the torsion spring 108 occurs when the tension increases, causing the annular belt to lift the tensioner arm 104 away from the annular belt. When the spring torque increases, the tensioner resists the rotation of the winding direction through frictional damping force; while when the torque decreases, the frictional damping force decreases accordingly.

[0019] Reference Figure 4 and Figure 5 The annular flange 139 of the pivot bushing 130 is sandwiched between the upper surface 121a of the arm bushing 105 and the arm plate 140. The bushing 130 is typically made of wear-resistant plastic and has multiple grooves 134 on a first surface facing the pivot tube 103 and a second surface facing the arm plate 140 for receiving grease. The annular flange 139 and the bushing 130 as a whole function as a support surface for the rotation and translation of the tensioner elements about and along the pivot axis. Although the bushing 130 in this embodiment is made of wear-resistant plastic, the use of other suitable bushing materials or bearing structures is also within the scope of this invention.

[0020] Reference Figures 3 to 6 The arm bushing 105 extends from the arm 104 around the first axis A. The arm bushing 105 is a cylindrical sleeve structure, relative to... Figure 4 and Figure 5 The paper orientation has a top opening 135 and a bottom opening 137. The arm bushing 105 defines a window 122 extending through its wall, i.e., a slot extending from the outer surface 109 of the arm bushing 105 to the inner surface 113. The window 122 is located closest to the top opening 135 and adjacent to the pulley pivot tube 107, such that the last coil spring 115 of the torsion spring 108 extending from the second spring end 112 can be operatively engaged with the damping lug 132 of the bushing 130 housed within the window 122, as... Figure 1 and Figure 3 As shown. The window 122 has an extended flange 124, the shape of which is adapted to support the last coil 115 of the torsion spring 108, so as to assist in abutting the last coil against the damping lug 132.

[0021] like Figure 5 As best seen, the top opening 135 of the arm bushing 105 can be configured as a flanged radial shoulder, which defines an upper surface 121a surrounded by a perimeter 121b. The flanged radial shoulder accommodates the annular flange 139 of the bushing 130 and the arm plate 140. The arm 104 may have an arcuate track 129 recessed in the arm bushing 105 near the bottom opening 137. The arcuate track 129 defines or limits the rotation angle of the arm 104 about a first axis of rotation A. In the assembled state, the top opening 135 of the arm bushing 105 is closed by the arm plate 140, and the bottom opening 137 is seated on the base 102, thereby also closing the bottom opening 137.

[0022] The arm 104 also includes a pulley pivot tube 107. The pulley pivot tube 107 has a top hole 125 (marked in...). Figure 5 ) and bottom hole 127 (marked in Figure 6 The inner surface of the bottom hole 127 may include a spring-end positioning structure 128. The spring-end positioning structure 128 may be a portion of a planar or flat-walled section of a generally cylindrical hole. In another embodiment, the spring-end positioning structure may be a key or keyway that mates with a corresponding mating structure on the second spring end 112. The top hole 125 defines a recessed socket 126, which is preferably visible in... Figure 2The socket 126 is configured to receive a tool, particularly after the tensioner has been installed into the engine system, for lifting the tensioner arm (applying force to the torsion spring to move the arm) to fit the annular belt onto the belt engagement surface 117 of the pulley. In one embodiment, the socket 126 has a plurality of toothed receiving structures. The socket should have a sufficient number of toothed receiving structures to prevent tool slippage that could damage the socket.

[0023] Now refer to Figures 1 to 4 as well as Figures 7 to 8 The base 102 includes a pivot tube 103 and a spring abutment structure 150, on which a first end 110 of a torsion spring is operably abutted to bias the arm 104 in the belt tension direction. The spring abutment structure 150 may be a protrusion or a groove on the base 102. Opposite to the spring abutment structure 150 is a locating pin 160, which extends downward from the bottom surface 162 (also referred to as the mounting surface) of the base. The locating pin 160 is configured to be received in a mating recess on the engine surface, the recess being positioned to properly mount the belt tensioner 100 for engagement with the annular belt. The base 102 may include an arcuate protrusion 152 configured to mate with an arcuate track 129 within the arm sleeve 105. Extending radially outward from the arcuate protrusion 152 is a spring support 154. The spring support 154 is configured to support the first coil spring 111 of the torsion spring. The first coil spring 111 is a spring coil extending from the first spring end 110.

[0024] Reference Figure 7 and Figure 8 The pivot tube 103 has an open free end 155 and a generally closed opposite end 157. The opposite end 157 defines a through hole 158 (preferably visible in...). Figure 2 , Figure 8 and Figure 10 The hole 158 is configured to receive a mounting bolt for mounting the base 102 (and consequently the belt tensioner 100) to the engine surface. The hole 158 may include an axial flange 163 extending inward toward the free end 155 of the pivot tube 103. The base 102 may include an annular flange 164 projecting axially upward around the pivot tube 103, with an inner diameter ID larger than the outer diameter OD of the pivot tube 103, thereby spacing the annular flange 164 from the root 166 of the pivot tube 103. The gap formed between them is configured to receive a bottom opening 137 of the arm bushing 105, thereby closing the arm bushing when the arm 104 and base 102 are engaged in the assembled state. The end of the free end 155 of the pivot tube 103 has a splined or grooved outer surface 156 configured to mate with the arm plate 140.

[0025] Refer again Figure 1 and Figure 4 The arm plate 140 is housed within the flanged radial shoulder of the arm 104 and is keyed to the free end 155 of the pivot tube, more specifically, to the splined or grooved outer surface 156 of the pivot tube. The arm plate 140 surrounds the bushing 130 within the arm 104. The arm plate 140 can deform during installation to act as a spring pressure plate, securing the components together. Examples of such methods can be found in U.S. Patents 6,575,860 and 9,249,866.

[0026] Turn now Figure 9 and Figure 10 This diagram illustrates a second embodiment of the belt tensioner 100a, whose main body and components are identical to those of the first embodiment; therefore, all reference numerals are consistent. The difference in this second embodiment lies in the pulley lifting mechanism 200, used for mounting the belt tensioner; unlike the pulley pivot tube 107 in the first embodiment, which has a recessed insertion port, the pulley pivot tube 107 in this embodiment is shortened and equipped with a nut 202. The nut 202 has a pivot post 203 housed within a rolling bearing 116, and a protrusion 205 extending axially upward from the pulley 114. The nut 202 is threaded onto the second end leg 112 of a torsion spring 108. The second end leg 112 has an external thread 240, and the inner bore of the nut 202 has a matching thread 206. The nut 202 has a radially outwardly extending annular flange plate 208. In the assembled state, the annular flange plate 208 abuts against the dust cover 120, securing the dust cover in place to protect the bearing 116 of the pulley 114 from contaminants and debris. The connection between the nut and the second spring end is not limited to a threaded connection. In other embodiments, the second spring end of the torsion spring is connected to the nut by brazing, laser welding, adhesive bonding, or any equivalent method.

[0027] During operation, under normal tension, when the belt presses against the pulley 114 connected to the arm 104, the arm will rotate about its pivot axis A, thereby tightening the torsion spring 108. As the torsion spring winds, it applies a spring torque to the arm 104, causing the arm and pulley to move towards the belt, remain against or press against the belt. Figure 3As shown, the last coil 115 of spring 108 is positioned adjacent to the damping lug 132 of bushing 130. Therefore, when arm 104 rotates in response to belt load or other forces of the annular power transmission element (which tension the belt in the section where the tensioner is located), spring 108 coils up, the coil diameter decreases, the coil contracts radially, and the damping lug 132 is compressed, causing frictional engagement between bushing 130 and the pivot tube 103 of base 102 to provide asymmetric damping. Subsequently, when the belt load or other forces of the power transmission element disappear, the torque accumulated in spring 108 pushes arm 104 to rotate in the tension direction T, and spring returns to a less coiled state. As spring 108 returns to a less coiled state, the force acting on damping lug 132 decreases, and bushing 130 disengages from frictional engagement with the pivot tube 103 of base 102.

[0028] The arm 104 and base 102 may be made of die-cast aluminum or other metals. Partial plastic materials may also be used if the plastic strength is sufficient to meet the requirements of the vehicle engine environment. In one embodiment, the metal material is aluminum or an aluminum alloy. The torsion spring 108 may be made of steel, but other suitable alternative materials (or combinations of materials / components) may also be considered for manufacturing the spring. The arm plate 140 is a hardened steel plate in an exemplary embodiment, and the bushing 130 is typically made of abrasion-resistant plastic. The abrasion-resistant plastic may include, but is not limited to: all polyamides (PAs), including 66 nylon, 6 nylon, 11 nylon, 12 nylon, 69 nylon, 612 nylon, and 610 nylon, polyamide 46 nylon; polyetherimide (PEI); polysulfone (PSU); polyethersulfone (PES); polyoxymethylene (POM), i.e., acetal; polyetheretherketone (PEEK); polyphenylene sulfide (PPS); polyphthalamide (PPA), i.e., amorylene; polyphenylene ether (PPO); and amorphous nylon.

[0029] The belt tensioner described herein offers numerous advantages, many of which have been explained above. This paragraph supplements some of these advantages. The belt tensioner disclosed herein eliminates the need for pulley bolts, resulting in greater cost-effectiveness and allowing the spring end to be positioned inside the pulley pivot tube (in place of the bolt) for better balance of hub loads. More specifically, the spring force of the torsion spring (which can be a very durable round wire spring) balances the hub load force and the spring reaction force, and the spring moves with the arm, counteracting the hub load force throughout the arm's entire range of rotation. Furthermore, since no bolts are required, the bearing / pulley is secured to the pivot tube by deforming the top of the pivot tube toward the dust cover and / or mounting ring (e.g., radial riveting or spinning), preventing inner ring deformation and enabling quicker installation. This design allows for a shortest possible arm for the belt tensioner while maximizing the pulley's size. Additionally, the absence of bolts allows for a recessed socket at the opposite end of the pulley pivot tube to accommodate tools for winding the tensioner during belt installation. The recessed socket does not increase the installation height of the belt tensioner.

[0030] It should be understood that the application or use of the various embodiments is not limited to the construction details and the arrangement of components and steps shown in the drawings and description. Features of illustrative embodiments, constructions, and variations may be implemented or incorporated in other embodiments, constructions, variations, and modifications, and may be practiced or performed in various ways. Furthermore, unless otherwise stated, the terminology and expressions used herein are selected to facilitate the reader's description of illustrative embodiments of the invention and are not intended to limit the invention.

[0031] The present invention has been described in detail above through preferred embodiments. Obviously, modifications and variations can be made without departing from the scope of the present invention as defined by the appended claims.

Claims

1. A high-bias belt tensioner, comprising: A base, wherein the base is provided with a pivot tube defining a first axis of rotation; An arm having an arm sleeve rotatably fitted onto the pivot tube, and the arm having a pulley pivot tube defining a second axis of rotation; A torsion spring is sleeved on the outer surface of the arm bushing, with its first spring end attached to the base and its second spring end oriented and housed inside the pulley pivot tube. A pulley, which is mounted on a pulley pivot tube and can rotate about it; as well as A dust cover is disposed on the pulley pivot tube and adjacent to the pulley; The first end of the pivot tube is deformed toward the dust cover to secure the pulley without using pulley bolts.

2. The high-bias belt tensioner according to claim 1, wherein, The first end of the pulley pivot tube defines a socket opposite the second spring end, configured to receive a tool.

3. The high-bias belt tensioner according to claim 2, wherein, The socket has multiple tooth-accommodating structures.

4. The high-bias belt tensioner according to claim 2, wherein, The second end of the pulley pivot tube has an annular hole, the annular hole including an axial flange extending inward toward the first end of the pivot tube.

5. The high-bias belt tensioner according to claim 1, wherein, The arm bushing defines an opening, and the tensioner further includes a bushing housed inside the arm bushing and located between the pivot tube and the inner surface of the arm bushing. The bushing has a lug extending out of the opening, the lug being actively engaged with the coil of the torsion spring.

6. The high-bias belt tensioner according to claim 5, wherein, The bushing includes an axial slit opposite to the lug. When the torsion spring is wound around the outer surface of the arm, the bushing can be compressed against the pivot tube to dampen the movement of the arm.

7. The high-bias belt tensioner according to claim 5, wherein, It also includes an arm plate, which is received within a shoulder recess of the arm bushing and engages with a first end of the pivot tube, wherein the arm plate surrounds the bushing inside the arm.

8. The high-bias belt tensioner according to claim 7, wherein, The arm plate provides a rigid surface for the arm and the bushing to rotate against each other.

9. The high-bias belt tensioner according to claim 7, wherein, The bushing has multiple grooves on a first surface facing the pivot tube and a second surface facing the arm plate for receiving grease.

10. The high-bias belt tensioner according to claim 1, wherein, The base includes an arcuate protrusion that engages with an arcuate track on the pivot tube housing of the arm, wherein the arcuate track limits the rotation angle of the arm about the first rotation axis.

11. The high-bias belt tensioner according to claim 1, wherein, The base includes a locating pin that extends from the mounting surface of the base and is positioned opposite the spring abutment structure.

12. The high-bias belt tensioner according to claim 1, wherein, The torsion spring is an exposed torsion spring.

13. A high-bias belt tensioner, comprising: A base, wherein the base is provided with a pivot tube defining a first axis of rotation; An arm having an arm sleeve rotatably fitted onto the pivot tube, and the arm having a pulley pivot tube defining a second axis of rotation; A torsion spring is sleeved on the outer surface of the arm bushing, with its first spring end attached to the base and its second spring end oriented and housed inside the pulley pivot tube. A pulley, wherein the rolling bearing of the pulley is rotatably mounted on the pulley pivot; A dust cover is disposed on the rolling bearing; Wherein, the pulley pivot tube extends through the rolling bearing, and the second spring end of the torsion spring extends through the pulley pivot tube and the rolling bearing and extends out of the pulley; A nut is disposed on the second spring end of the torsion spring and engages with the dust cover, and the nut defines a protrusion configured to receive a tool.

14. The high-bias belt tensioner according to claim 13, wherein, The second spring end of the torsion spring is threaded, and the nut has a matching thread.

15. The high-bias belt tensioner according to claim 14, wherein, The second spring end of the torsion spring is fixed to the nut by brazing, laser welding or adhesive.

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