Belt tensioner with supplemental force element
View Patent ↗Zed-type belt tensioners are described that include an arm having a first end rotatable about a first axis to move a second end of the arm into engagement with a belt, a tensioner component coupled to the first end of the arm, and a supplemental force element positioned between the arm and the tensioner component. The second end of the arm while tensioning a belt experiences a hub load applied by the belt and the supplemental force element is positioned at a point to apply a force that counteracts the hub load thereby reducing cocking of the arm. Also described herein are methods of counteracting the hub load using such belt tensioners and methods of assembly of such belt tensioners.
1. A Zed-type belt tensioner comprising:
an arm having a first end comprising an arm arbor, the arm arbor defining a housing, and having a second end, wherein the first end is rotatable about a first axis to move the second end into engagement with a belt and the second end experiences a hub load during engagement with the belt;
a cap mated to the arm, the cap comprising an abutment feature;
a support member having the arm seated therein;
a primary spring seated in the housing of the arm arbor and having a first end coupled to the arm and a second end coupled to the abutment feature of the cap, the primary spring urging the arm to rotate about the first axis;
and
a secondary spring positioned between the arm and the cap or between the arm and the support member;
wherein the secondary spring applies an axial force non-uniformly across a surface of the arm;
wherein waves or coils of the secondary spring are only seated against the surface of the arm at a predetermined position that is opposite the hub load of the Zed-type belt tensioner to apply an axial force that counteracts the hub load, in an opposing direction relative to a direction of a force of the hub load, thereby reducing cocking of the arm.
2. The tensioner of claim 1 , wherein the secondary spring is an annular wave spring comprising a flat first half and a waved second half with one or more waves therein, wherein the supplemental force is applied by the waved second half.
3. The tensioner of claim 1 , wherein the secondary spring is one or more of a wave spring segment comprising at least one wave, a compression spring, a die spring, and a cantilever spring.
4. The tensioner of claim 1 , wherein the secondary spring is positioned to apply the supplemental force by urging the arm toward a support member.
5. The tensioner of claim 4 , wherein the the cap is non-rotatable about the first axis and comprises a track in which the secondary spring is seated.
6. The tensioner of claim 5 , wherein the secondary spring is seated in a bushing positioned between the secondary spring and the arm, and the cap is fixedly coupled to the supplemental bushing.
7. The tensioner of claim 1 , wherein the cap is fastened to the support member.
8. A Zed-type belt tensioner comprising:
an arm having a first end and a second end, wherein the first end is rotatable about a first axis to move the second end into engagement with a belt; wherein the second end experiences a hub load during engagement with the belt;
a tensioner component coupled to the first end of the arm; and
a supplemental force element positioned between the arm and the tensioner component to apply a force that counteracts the hub load, thereby reducing cocking of the arm;
wherein the supplemental force element is an annular wave spring comprising a flat first half and a waved second half with one or more waves therein, wherein the supplemental force is applied by the waved second half.