Patent Description:
Belt tensioners have been utilized in many belt systems. It is conventional practice in belt tensioners to apply a constant belt tensioning force which compensates for increases in belt length due to wear and other factors. A common type of conventional belt tensioner includes a fixed structure and a pivoted structure pivotally mounted on the fixed structure by a pivot assembly. The pivoted structure carries a belt-engaging pulley. A coil or torsion spring is mounted in surrounding relation to the pivot assembly and has its ends connected between the fixed and pivoted structures so as to bias the latter toward a position of maximum belt take-up so that the spring biasing force decreases as the pivoted structure moves from a position of minimum take up to a position of maximum belt take-up. Despite this varying spring force within the range of movement provided, a substantially constant belt tension is maintained.

When belt tensioners are installed on an engine they should be installed so as to apply a predetermined static tensioning force to the belt. In addition, the pivoted structure, which conventionally carries the pulley, is movable between two positions defined by end stops. During the adjustment or installation of the tensioner, an adjusting member or an eccentric adjusting member, which forms part of the fixed structure, is adjusted to move the pivoted structure into a position between the stops, wherein the belt tensioning pulley is disposed in a predetermined static tensioning relation to the belt.

Many adjusters for tensioners are manufactured as a two-piece construction, for example, in an injection molded, die cast or stamped process. The two-piece manufacturing process can be costly and time-consuming due to, for example, the re-tooling efforts that are needed when manufacturing different sized eccentric adjusters and different sized eccentric tensioners.

<CIT> discloses a tensioner comprising a shaft having a shaft portion engageable with a mounting surface, a pivot arm pivotally engaged with the shaft about an axis, a plate fixedly attached to the shaft, the plate disposed on an end of the shaft opposite the shaft portion, a torsion spring engaged between the pivot arm and the plate for biasing the pivot arm, the torsion spring disposed opposite the shaft portion and immediately adjacent the plate, a pulley journalled to the pivot arm, the center of rotation of the pivot arm disposed eccentrically from the center of rotation of the plate, the pivot arm having a tab which cooperates with a portion on the plate to indicate a relative position of the pivot arm with respect to the plate during installation, and a tool receiving portion on the plate for rotationally adjusting the plate during installation.

What is needed is a tensioner adjuster that can be more economically and sustainably manufactured for a variety of differently sized eccentric adjusters and tensioners.

The present invention provides a one-piece tensioner adjuster as recited in claim <NUM> and a tensioner as recited in claim <NUM>. Optional features are recited in the dependent claims.

Other aspects of the invention will be explained or made obvious by the following description of the invention and the accompanying drawings.

The accompanying drawings, which are incorporated in and form a part of the specification, illustrate preferred embodiments of the present invention, and together with a description, serve to explain the principles of the invention.

The tensioner adjuster of the present invention comprises an eccentric adjuster. The eccentric adjuster may be used to move a tensioner into proper engagement with a belt during installation. The eccentric adjuster may be manufactured by stamping a single piece of material, e.g., a sheet metal material, and forming the single piece of stamped material into an adjuster structure that assists in the installation of a belt tensioner, for example, onto a motor vehicle engine by moving the pivoted structure into a position between stops in which the belt tensioning pulley is placed into predetermined static tensioning relation to the belt. The process of stamping the adjuster material into a single piece and forming the single piece of stamped material into the adjuster structure enables eccentric adjusters to be manufactured with different sizes for use with different sized eccentric tensioners, without requiring tooling changes during manufacturing. The adjusters of the present disclosure are accordingly made without expensive and time-consuming re-tooling efforts during manufacturing, which substantially reduces per unit adjuster manufacturing costs. The reduction in re-tooling during manufacturing not only provides significant economic benefits, but also creates a more environmentally sustainable manufacturing process.

<FIG> illustrate a tensioner <NUM> with a one-piece adjuster <NUM> according to an embodiment of the present invention.

Tensioner <NUM> comprises an adjuster <NUM> that is eccentric and used to move tensioner <NUM> into proper engagement with a belt during installation, for example, during the installation of tensioner <NUM> onto a motor vehicle engine, as discussed herein. It should be appreciated from the foregoing that <FIG> illustrate the same adjuster embodiment illustrated in <FIG>.

During installation, adjuster <NUM> is rotated about a fastener, such as a bolt or stud or any other suitable fastener (fastener not shown), that passes through an opening <NUM> defined in adjuster <NUM>. When the fastener extends through opening <NUM>, the fastener is engaged with, or guided or held in place by, engaging members <NUM>, <NUM> (of respective first and second guide portions 59a, 59b of adjuster <NUM> as discussed below). The fastener inserted into opening <NUM> extends to a distal end of tensioner <NUM> where the fastener secures tensioner <NUM> to, for example, a motor vehicle engine. The center of the fastener that extends through opening <NUM> and is guided or held by the first and second engaging members <NUM>, <NUM> defines an axis of rotation B-B for the fastener (See, <FIG>). Axis B-B is eccentrically offset from an axis of rotation of pulley <NUM> C-C (See, <FIG>), and is eccentrically offset from an axis of rotation of the pivotal arm <NUM> of tensioner <NUM> (the axis of rotation for arm <NUM> is unlabeled). Eccentric adjuster <NUM> is used to precisely load a belt (not show) that is engaged with pulley <NUM> with a predefined tension by compensating for all component tolerances. Adjuster <NUM> is used during belt installation and locked in place once the belt is installed by fully engaging the fastener with a mounting surface, for example, with motor vehicle engine. Eccentric in the term eccentric adjuster <NUM> refers to the axis of fastener rotation B-B not being coaxial with the axis of rotation C-C of a pulley <NUM> or with the axis of rotation of arm <NUM>, which is defined by another axis (unlabeled) that is substantially parallel to axis B-B.

Pulley <NUM> engages a belt to provide belt tension or load. Pulley <NUM> is journalled to arm <NUM> about a bearing or bearing assembly <NUM>. Pulley <NUM> is engaged with an outer race of bearing <NUM>. Bearing <NUM> comprises a ball bearing but may comprise a needle bearing or any other suitable bearing.

Arm <NUM> comprises or has a center bore or opening <NUM> defined therein. Arm <NUM> is biased by a coil or torsion spring <NUM> to urge pulley <NUM> into the belt (not shown). Arm <NUM> pivots about sleeve <NUM> about a bushing <NUM>. Bushing <NUM> allows arm <NUM> to rotate smoothly about sleeve <NUM> and contributes to friction damping. Bushing <NUM> may comprise a low friction material for facilitating the relative movement of arm <NUM>, e.g., a material comprising brass, copper and sintered metal. The pivotal movement of arm <NUM> about sleeve <NUM> results in a translational movement of pulley <NUM> that allows tensioner <NUM> to compensate for any changes in belt length as the belt stretches over time and as the drive length changes from thermal expansion.

Arm <NUM> is engaged with an inner race of bearing <NUM>. Pulley <NUM> is pressed into engagement against the belt by a torsion spring <NUM>. A first end or arm engaging end <NUM> of torsion spring <NUM> is engaged with a slot <NUM> defined in arm <NUM>. A second opposite end or base engaging end <NUM> of torsion spring <NUM> is engaged with base <NUM> in a slot (not labeled) defined in a spring engaging member <NUM> of base <NUM>.

Base <NUM> is statically fixed during installation of tensioner <NUM> to a mounting surface, such as an engine of a motor vehicle (not shown). Spring torque from torsion spring <NUM> and the effective arm length of arm <NUM> creates a belt load or tension. Tang <NUM> of base <NUM> engages a cooperating receiving member on the mounting surface such as a hole in the mounting surface (not shown) and is used to prevent rotation of base <NUM> during installation of tensioner <NUM>. While base <NUM> is used to mount tensioner <NUM>, base <NUM> is also used to secure an end of the torsion spring <NUM>, e.g., to secure base engaging end <NUM> of torsion spring <NUM> in a slot defined in spring engaging member <NUM> of base <NUM>.

Sleeve <NUM> is attached or fixed to base <NUM>, e.g., via a mechanical interference fit, and is generally or substantially cylindrically shaped having a bore <NUM> defined therein. Sleeve <NUM> and its bore extend from a distal end <NUM> of sleeve <NUM> to a proximal end <NUM> of sleeve <NUM>. Distal end <NUM> of sleeve <NUM> comprises a circumferential collar <NUM>. Sleeve <NUM> further comprises a shoulder 72a that extends circumferentially around, and is defined by, an interior or inside wall of the bore <NUM> defined in sleeve <NUM> (See <FIG> showing shoulder 72a of sleeve <NUM>).

A damper <NUM> is mounted to sleeve <NUM> and arranged in tensioner <NUM> between base <NUM> and arm <NUM> to act as a damping control member. Damper <NUM> is held axially by sleeve <NUM> and is rotationally fixed by, for example, spring <NUM> being inserted through a slot or opening in the damper <NUM> that may align rotationally with the slot defined in the spring engaging member <NUM> of base <NUM>. Damper <NUM> controls and reduces oscillations of arm <NUM> during operation and may comprise and material suitable for reducing and controlling oscillations of arm <NUM>.

Arm <NUM> comprises an arm indicator <NUM> that cooperates with a base indicator <NUM> of base <NUM> to display when tensioner <NUM> is properly installed and loaded during installation. Pulley <NUM> comprises a belt engaging surface (not labeled), which may be flat as shown, or any other suitable shape or profile for engaging a belt.

Referring now more specifically to an embodiment of a one-piece adjuster of the present disclosure, <FIG> illustrate one embodiment of a tensioner <NUM> having an adjuster <NUM>, and one embodiment of the adjuster <NUM> isolated by itself for use with a tensioner, such as tensioner <NUM>. In particular, <FIG> illustrate adjuster <NUM> isolated from tensioner <NUM> but for use with a tensioner such as tensioner <NUM>. Adjuster <NUM> may be manufactured by stamping a single piece of material, e.g., a single piece of sheet metal material, into a substantially flat one-piece structure such as the structure illustrated in <FIG>. The substantially flat one-piece stamped adjuster material may then be formed into an adjuster structure, such as the structure of adjuster <NUM> illustrated in <FIG>, <FIG>, and <FIG> by, for example, folding the stamped adjuster material using a rolling process. The adjuster <NUM> as formed comprises a substantially planar plate portion <NUM> and first and second opposing guide portions 59a, 59b. First and second guide portions are connected to opposing sides of planar plate portion <NUM> via first and second neck portions 58a, 58b, respectively. First and second guide portions 59a, 59b further comprise first and second engaging members <NUM>, <NUM>, respectively, each of which is constructed and arranged to engage the fastener, such as the bolt or stud (as discussed above), when the fastener is inserted into adjuster <NUM> for rotation about axis B-B during installation of tensioner <NUM>.

Plate portion <NUM> comprises, or defines therein, a tool receiving portion <NUM>. During installation, a tool, such as an Allen wrench (not shown), may be inserted or engaged at tool receiving portion <NUM> of adjuster <NUM> for rotating adjuster <NUM> about the fastener. Adjuster <NUM> may be rotated about the fastener that is inserted through opening <NUM> of plate portion <NUM>. The fastener extends past opening <NUM> substantially perpendicular to plate portion <NUM> to a distal end of tensioner <NUM>, where the fastener secures or mounts the tensioner to, for example, a motor vehicle engine. The fastener portion that extends beyond opening <NUM> is engaged with first and second fastener engaging members <NUM>, <NUM> of first and second guide members 59a, 59b, respectively, as discussed below.

First neck portion 58a is formed so as to be curved or bent into a structure that is substantially or generally U-shaped with a parallel section 58a1 of the U-shape extending substantially or generally radially inwardly and substantially parallel to plate portion <NUM>. Extending from opposing sides of parallel section 58a1 are first and second reinforcing supports 58a2, 58a3, respectively, each of which is formed so as to be curved or bent with sections <NUM>, <NUM> that extend generally parallel to axis B-B (or the axis of bore <NUM> defined in sleeve <NUM>) and perpendicular to plate portion <NUM> towards an underside or proximal surface 56a of plate portion <NUM>. Sections <NUM>, <NUM> of reinforcing supports 58a2, 58a3 each extend to the underside or proximal surface 56a without physically contacting surface 56a.

Similar to first neck portion 58a, second neck portion 58b is formed so as to be curved or bent into a structure that is substantially or generally U-shaped with a parallel section 58b1 of the U-shape extending substantially or generally radially inwardly and substantially parallel to plate portion <NUM>. Extending from opposing sides of parallel section 58b1 are first and second reinforcing supports 58b2, 58b3, respectively, each of which is formed so as to be curved or bent with sections <NUM>, <NUM> that extend generally parallel to axis B-B (or the axis of bore <NUM> defined in sleeve <NUM>) and perpendicular to plate portion <NUM> towards the underside or proximal surface 56a of plate portion <NUM>. It should be appreciated and understood that while reinforcing support 58b3 is shown in the adjuster figure of <FIG>, reinforcing support 58b3 is obscured and not fully shown in <FIG> and <FIG>, but is located in <FIG> and <FIG> in a position opposite 58b2 similar to reinforcing support 58a3 of first neck portion 58a, which is clearly shown in <FIG> and <FIG>. Sections <NUM>, <NUM> of reinforcing supports 58b2, 58b3 each extend to the underside or proximal surface 56a without physical contacting surface 56a. When adjuster <NUM> is rotated during installation, a relatively high torque is applied by the head of the fastener (e.g., a bolt head) to the adjuster <NUM>, e.g., in the range of <NUM>-<NUM> N·m. This high torque imparts a force to adjuster plate portion <NUM>, which may cause plate portion <NUM> to mechanically deform, e.g., deform or bend in a generally downwardly direction from the perspective of looking through opening <NUM> from a topside surface of plate <NUM> along the axis of rotation B-B towards the distal end of adjuster <NUM>. Such deformation can cause adjuster <NUM> to perform poorly resulting in improper tensioning of tensioner <NUM> during its installation and even leading to breakage or failure of plate portion <NUM>. Reinforcing supports 58a1, 58a2, 58b2, 58b3 act to reduce or eliminate such mechanical deformation that may occur to adjuster plate portion <NUM> when such torque is applied during installation, thereby improving the quality, effectiveness and durability of adjuster <NUM> and of tensioner <NUM> having adjuster <NUM>.

First and second guide portions 59a, 59b are integral with, and extend generally longitudinally from, first and second neck portions 58a, 58b, respectively, and are generally perpendicular to plate portion <NUM> and parallel to axis B-B. First guide portion 59a comprises two legs <NUM>, <NUM> extending longitudinally and substantially perpendicular to plate potion <NUM> and substantially parallel to axis B-B. Positioned between legs <NUM>, <NUM> is a sleeve engaging tab <NUM> that extends generally radially outwardly from axis B-B to a distal end portion 596a of tab <NUM>. Distal end portion 596a extends radially outwardly to engage the shoulder 72a of sleeve <NUM>. Shoulder 72a extends circumferentially around, and is defined by, an interior or inside wall of the bore <NUM> defined in sleeve <NUM> (See <FIG> showing shoulder 72a of sleeve <NUM>).

Second guide portion 59b, which is opposite first guide portion 59a, comprises two legs <NUM>, <NUM>, which like legs <NUM>, <NUM> of first guide portion 59a, extend generally longitudinally and substantially perpendicular to plate potion <NUM> and substantially parallel to axis B-B. Positioned between legs <NUM>, <NUM> is a sleeve engaging tab <NUM> that extends generally radially outwardly from bolt axis B-B to a distal end portion 597a of tab <NUM>. Distal end portion 597a extends radially outwardly to engage the shoulder 72a of sleeve <NUM>. Sleeve engaging tabs <NUM> and <NUM> and their respective distal end portions 596a, 597a engaging sleeve shoulder 72a act to lock or engage adjuster <NUM> with sleeve <NUM> so that adjuster <NUM> can be secured or held axially in place during transport and assembly, e.g., assembly onto a motor vehicle engine. In an embodiment, sleeve engaging tabs <NUM> and <NUM> may be formed so as to be flexible and biased radially outwardly to engage and lock adjuster <NUM> with sleeve <NUM> so that adjuster <NUM> can be secured or held in place during transport and assembly, e.g., onto a motor vehicle engine. It should be appreciated that in certain embodiments, an outside diameter defined by a substantially circular shape drawn around, and defined by, the outside surface of legs <NUM>, <NUM>, <NUM>, <NUM> may be slightly less than an inside diameter of the bore <NUM> of sleeve <NUM> so that legs <NUM>, <NUM>, <NUM>, <NUM> of first and second guide member 59a, 59b may be inserted into and rotatable within bore <NUM> of sleeve <NUM>.

First guide portion 59a further comprises a fastener engaging member <NUM> that is constructed and arranged to engage or interface with the fastener that extends through opening <NUM> of adjuster <NUM> to enable adjuster <NUM> to be guided by and rotatable about the fastener, i.e., about axis B-B during the installation of tensioner <NUM>. Fastener engaging member <NUM> extends from, and is integral with, leg portion <NUM> and includes a body section that extends longitudinally and substantially perpendicular to plate portion <NUM> and parallel to axis B-B. A foot <NUM> extends from the body section in a substantially or generally radially inwardly direction towards the axis B-B so as to engage or interface with the fastener inserted into opening <NUM> of arm <NUM> for installation of tensioner <NUM>. Fastener engaging member <NUM> may be substantially or generally L-shaped as illustrated, but may form any other suitable shape that enables member <NUM> to engage the fastener and ensure that the fastener, when inserted into arm hole <NUM>, stays substantially perpendicular to plate portion <NUM> and parallel to the pulley rotational axis C-C and to the arm rotational axis (not labeled) for proper installation of tensioner <NUM>. Foot <NUM> may include a distal or toe end <NUM> that is configured to engage or interface with the fastener inserted into the opening <NUM> of arm <NUM>. In the illustrated embodiment, engaging surface 604a of toe end <NUM> engages the fastener when the fastener is inserted into the opening <NUM> of arm <NUM>.

Second guide portion 59b, like first guide portion 59a, further comprises a fastener engaging member <NUM> that is constructed and arranged to engage or interface with the fastener to enable adjuster <NUM> to be guided by and rotatable about the fastener, i.e., about axis B-B, during the installation of tensioner <NUM>. Fastener engaging member <NUM> extends from, and is integral with, leg portion <NUM> and includes a body section that extends longitudinally and substantially perpendicular to plate portion <NUM> and parallel to axis B-B (and may extend in substantially the same plane as the body section of fastener engaging member <NUM>). A foot <NUM> extends from the body section in a substantially or generally radially inwardly direction towards the axis B-B so as to engage or interface with the fastener inserted into opening <NUM> of arm <NUM> for the installation of tensioner <NUM>. Fastener engaging member <NUM> may be substantially or generally L-shaped as illustrated, but may form any other suitable shape that enables member <NUM> to engage the fastener and ensure that the fastener, when inserted into arm hole <NUM>, stays substantially perpendicular to plate portion <NUM> and parallel to both the pulley rotational axis C-C and to the arm rotational axis (not labeled) for proper installation of tensioner <NUM>. Foot <NUM> includes a distal or toe end <NUM> that is configured to engage or interface with the fastener inserted into the opening <NUM> of arm <NUM>. In the illustrated embodiment, engaging surface 704a of toe end <NUM> engages the fastener when the fastener is inserted into opening <NUM> of arm <NUM>.

Foot <NUM> and foot <NUM> together may be angled radially inwardly at an angle, e.g., angled inwardly towards one another, such that that their respective distal or toe ends (and surfaces) form a curvature or arc that interfaces or engages with the curvature or arc formed by the outside surface of the fastener. That is, toe ends <NUM>, <NUM> of foot <NUM> and foot <NUM> may be generally or substantially arcuate or curved to engage with, interface with or substantially conform to the outside surface of the fastener. Foot <NUM> and foot <NUM> may form a V-shape when viewed, for example, from a direction looking through opening <NUM> and parallel to axis B-B towards a distal end of tensioner <NUM>. Together, foot <NUM> and foot <NUM> and their respective length, which extend radially inwardly to axis B-B to engage the fastener, allows adjuster <NUM> to hold the fastener substantially perpendicular to plate portion <NUM> and parallel to the pulley rotational axis C-C and to the arm rotational axis for proper installation of tensioner <NUM>, i.e., while adjuster <NUM> is rotated about the fastener.

Forming the adjuster of the present disclosure with first and second guide portions and respective fastener engaging members from a single piece of material allows the adjusters and tensioners of the present disclosure to be easily manufactured with different sized eccentric tensioners and different sized eccentric adjusters. For example, the first and second guide portions and the respective legs of the adjusters disclosed herein may be easily stamped and formed into various sizes and dimensions without requiring serious modification to tools used during manufacturing, thereby enabling the legs to fit into tensioners having sleeves of varying diameters (and hence tensioner pivot arms having center bores of varying diameters). The first and second guide portions and their respective fastener engaging members may likewise be easily stamped and formed into various sizes and dimensions without requiring serious modification to manufacturing tools, enabling the fastener engaging members to engage fasteners of different diameters and allowing the adjusters to be easily manufactured for use with tensioner adjusters of varying eccentricities. In one example, the length of each foot of the fastener engaging members can be easily cut to different lengths and formed so that they may extend to corresponding different lengths radially inwardly, thereby allowing the fastener engaging members to be made so as to engage larger or smaller fasteners and operate with larger or smaller sized eccentric adjusters, e.g., <NUM>, <NUM> or <NUM> eccentric adjusters.

Claim 1:
A one-piece tensioner adjuster (<NUM>) comprising:
a plate portion (<NUM>) comprising an opening (<NUM>) for receiving a fastener for installation of a tensioner (<NUM>);
a first neck portion (58a) extending from the plate portion (<NUM>); and
a second neck portion (58b) extending from the plate portion (<NUM>) on a side of the plate portion (<NUM>) opposite from the side of the plate portion (<NUM>) from which the first neck portion (58a) extends; characterised in that:
the first neck portion (58a) is a first curved neck portion and the second neck portion (58b) is a second curved neck portion; wherein the tensioner adjuster further comprises:
a first guide portion (59a) extending from the first curved neck portion (58a) and comprising a fastener engaging member (<NUM>) constructed and arranged to engage the fastener;
a second guide portion (59b) extending from the second curved neck portion (58b) and comprising a fastener engaging member (<NUM>) constructed and arranged to engage the fastener;
(i) a first reinforcing support (58a2) that extends from the first curved neck portion (58a);
(ii) a second reinforcing support (58a3) that extends from a side of the first curved neck portion (58a) that is opposite the side from which the first reinforcing support (58a2) extends;
(iii) a third reinforcing support (58b2) that extends from a side of second curved neck portion (58b); and
(iv) a fourth reinforcing support (58b3) that extends from a side of the second curved neck portion (58b) that is opposite the side of the second curved neck portion (58b) from which the third reinforcing support (58b2) extends.