Belt tensioner unit for internal combustion engine or the like

Claim 2

In a device having a belt which drivingly interconnects pulleys, a belt tensioning arrangement comprising: a base plate pivotally mounted on said device and selectively securable in a selected position; a support arm having first and second ends, said support arm being pivotally mounted on said base plate at a first end thereof so as to be pivotal about an axis; an idler pulley mounted on said support arm at a location between said first and second ends, said idler pulley being engageable with said timing belt; and a tensioner mechanism mounted on said base plate at a location distal from said axis, said tensioner mechanism including means for applying a bias to said second end of said support arm which biases said support arm in a first rotational direction which increases the force with which said pulley engages said timing belt and thus increases the tension therein.

Claim 3

A tensioning arrangement as claimed in claim 1, wherein said tensioner mechanism comprises: a housing in which a bore is formed; a first piston reciprocatively disposed in said bore in a manner to define a variable volume chamber, said variable volume chamber being filled with oil; a second piston reciprocatively disposed in an axis bore formed in said first piston, said second piston having a end engageable with said support arm; biasing means disposed in said variable volume chamber for biasing said first piston in a first axial direction; a reservoir in which oil is stored; a passage structure formed in said housing, first and second pistons, said passage structure being arranged to selectively establish fluid communication between said reservoir and said variable volume chamber; and a one-way check valve, said one-way check valve being disposed in said passage structure and arranged to permit oil from said reservoir to enter said variable volume chamber.

Claim 4

A tensioning arrangement as claimed in claim 2, wherein said housing is detachably secured to said base plate.

Claim 5

A tensioning arrangement as claimed in claim 2, wherein said reservoir comprises: a diaphragm which hermetically divides an oil storage chamber and an atmospheric pressure chamber.

Claim 6

A tensioning arrangement as claimed in claim 2, further comprising an oil seal disposed in said bore, said oil seal permitting reciprocative motion of said first and second pistons.

Claim 7

A tensioning arrangement as claimed in claim 1, further comprising a stopper, said stopper being selectively adjustable in a manner to prevent said tensioner mechanism from applying a bias to said support arm while said base plate is being selectively secured to said device.

Claim 8

A tensioning arrangement as claimed in claim 1, wherein said base plate includes a first aperture in which a pivot pin is received and second and third elongate apertures which are constructed and arranged to permit said base plate to be rotated by a limited amount about the axis of said pivot pin and to receive bolts which may be selectively tightened to secure said base plate in a selected position.

Claim 9

In a device having a belt which drivingly interconnects pulleys, a belt tensioning arrangement comprising: a base plate, said base plate being mounted on said device so as to be pivotal about a first axis and including means for selectively securing said base plate in a preselected position; a housing mounted on said base plate at a location distal from said axis; a support arm having first and second ends, said support arm being mounted at said first end on said base plate so as to be pivotal about a second axis, said second axis being essentially parallel with said first axis and located between said first axis and said housing; an idler pulley rotatably mounted on said support arm at a location intermediate of said first and second ends, said idler pulley being arranged to engage said belt; a piston reciprocatively disposed in said housing, said piston being arranged to abut said support arm at a location proximate said second end and between said second end and a third axis about which said idler pulley is rotatable, said piston being able to apply a bias which tends to cause said support arm to rotate in a rotational direction which increases the tension in said belt.

Claim 10

In a device having a belt which drivingly interconnects pulleys, a belt tensioning arrangement comprising: a base plate, said base plate being mounted on said device so as to be pivotal about a first axis and including means for selectively securing said base plate in a preselected position; a housing mounted on said base plate at a location distal from said axis; a support arm having first and second ends, said support arm being mounted at said first end on said base plate so as to be pivotal about a second axis, said second axis being essentially parallel with said first axis and located between said first axis and said housing; an idler pulley rotatably mounted on said support arm at a location intermediate of said first and second ends, said idler pulley being arranged to engage said belt; a piston reciprocatively disposed in said housing, said piston being arranged to abut said support arm at a location proximate said second end and between said second end and a third axis about which said idler pulley is rotatable, said piston being able to apply a bias which tends to cause said support arm to rotate in a rotational direction which increases the tension in said belt.