Double action belt tensioner
A belt tensioner comprises first and second pulleys, a main arm and a sub-arm. The first pulley is displacable relative to an engine, and the second pulley is displacable relative to the first pulley. The main arm is connected to the first pulley, and a first spring is connected to the main arm and resists displacement of the first pulley when the engine is started. The sub-arm is connected to the second pulley, and a second spring is connected between the main arm and the sub-arm and maintains the second pulley generally equidistant from the first pulley while the engine is running.
1 . A belt tensioner for an internal combustion engine of a motor vehicle, the belt tensioner comprising:
a first pulley displacable relative to the engine;
a second pulley displacable relative to the first pulley;
means for resisting displacement of the first pulley when the engine is started; and
means for maintaining the second pulley generally equidistant from the first pulley while the engine is running.
2 . The belt tensioner of claim 1 wherein the means for resisting displacement of the first pulley comprises a main arm connected to the first pulley, and a sub-arm connected to the second pulley.
3 . The belt tensioner of claim 2 wherein the means for resisting displacement of the first pulley further comprises a first spring connected to the main arm.
4 . The belt tensioner of claim 3 wherein the first spring comprises a clock spring.
5 . The belt tensioner of claim 1 wherein the means for maintaining comprises a main arm connected to the first pulley, and a sub-arm connected to the second pulley.
6 . The belt tensioner of claim 5 wherein the means for maintaining comprises a second spring connected between the main arm and the sub-arm.
7 . The belt tensioner of claim 6 wherein the second spring comprises a coil spring.
8 . The belt tensioner of claim 1 wherein the means for resisting displacement of the first pulley comprises a main sliding block connected to the first pulley, and a sub-sliding block connected to the second pulley.
9 . The belt tensioner of claim 8 wherein the means for resisting displacement of the first pulley comprises at least one first spring connected to the main sliding block.
10 . The belt tensioner of claim 9 wherein the at least one first spring comprises a coil spring.
11 . The belt tensioner of claim 1 wherein the means for maintaining comprises a main sliding block connected to the first pulley, and a sub-sliding block connected to the second pulley.
12 . The belt tensioner of claim 11 wherein the means for maintaining comprises at least one second spring connected between the main sliding block and the sub-sliding block.
13 . The belt tensioner of claim 12 wherein the at least one second spring comprises a coil spring.
14 . A belt tensioner for an internal combustion engine, the belt tensioner comprising:
a first pulley displacable relative to the engine;
a second pulley displacable relative to the first pulley;
a main arm connected to the first pulley;
a first spring connected to the main arm and resisting displacement of the first pulley when the engine is started;
a sub-arm connected to the second pulley; and
a second spring connected between the main arm and the sub-arm and maintaining the second pulley generally equidistant from the first pulley while the engine is running.
15 . The belt tensioner of claim 14 wherein the first spring comprises a clock spring.
16 . The belt tensioner of claim 14 wherein the second spring comprises a coil spring.
17 . A belt tensioner for an internal combustion engine, the belt tensioner comprising:
a first pulley displacable relative to the engine;
a second pulley displacable relative to the first pulley;
a main sliding block connected to the first pulley;
at least one first spring connected to the main sliding block and resisting displacement of the first pulley when the engine is started;
a sub-sliding block connected to the second pulley; and
at least one second spring connected between the main sliding block and the sub-sliding block and maintaining the second pulley generally equidistant from the first pulley while the engine is running.
18 . The belt tensioner of claim 17 wherein the at least one first spring comprises a coil spring.
19 . The belt tensioner of claim 17 wherein the at least one second spring comprises a coil spring.