Timing drive tensioner assembly with pre-load and method

Abstract

A tensioner assembly for an engine timing drive includes a tensioner with a tensioner body having a fastener opening and defining a cavity with a plunger opening. A plunger is disposed in the cavity and a removable pin restrains the plunger in the cavity. The plunger is configured to be biased out of the plunger opening when the pin is removed. A protuberance extends outward from the tensioner body and is adapted to receive an applied torque. The tensioner body is configured to pivot about a center axis of the fastener opening in response to a predetermined torque applied to the protuberance. A method of assembling an engine timing drive includes applying a predetermined torque to a protuberance of a tensioner that is pivotably mounted to a cylinder block to rotate the tensioner toward a rotatable device such that the tensioner applies a predetermined load to the rotatable device.

What is claimed is: 
     
         1 . A tensioner assembly for an engine timing drive, the tensioner assembly comprising:
 a tensioner including:
 a tensioner body having a fastener opening and defining a cavity with a plunger opening; 
 a plunger disposed in the cavity and a removable pin restraining the plunger in the cavity, wherein the plunger is configured to be biased out of the plunger opening when the pin is removed; and 
 a protuberance extending outward from the tensioner body and adapted to receive an applied torque; 
   wherein the tensioner body is configured to pivot about a center axis of the fastener opening when fixed at the fastener opening in response to a predetermined torque applied to the protuberance.   
     
     
         2 . The tensioner assembly of  claim 1 , wherein the tensioner body includes a slot extending through the tensioner body with the protuberance between the fastener opening and the slot. 
     
     
         3 . The tensioner assembly of  claim 2 , further comprising:
 a shoulder bolt extending through the fastener opening; and   a locking bolt extending through the slot; wherein the locking bolt interferes with the tensioner body at an end of the slot to limit a range of motion of the tensioner body about the shoulder bolt in response to the predetermined torque applied to the protuberance.   
     
     
         4 . The tensioner assembly of  claim 2 , wherein:
 a first flange extends in a first direction from the tensioner body;   the fastener opening is in the first flange;   a second flange extends in a second direction from the tensioner body opposite to the first direction; and   the slot is in the second flange.   
     
     
         5 . The tensioner assembly of  claim 1 , wherein a side surface of the protuberance is hexagonal. 
     
     
         6 . The tensioner assembly of  claim 1 , wherein the protuberance extends from an outer side of the tensioner body; and wherein an inner side of the tensioner body opposite from the outer side is generally planar. 
     
     
         7 . The tensioner assembly of  claim 1  in combination with a tensioner arm having a convex surface;
 wherein a distal end of the plunger extending out of the cavity has a convex distal surface configured to be engaged with the convex surface of the tensioner arm when the tensioner body is pivoted about the center axis of the fastener opening toward the tensioner arm in response to the predetermined torque applied to the protuberance. 
 
     
     
         8 . An engine assembly comprising:
 a cylinder block;   a cylinder head supported on the cylinder block;   a crankshaft rotatably mounted on the cylinder block;   at least one camshaft mounted on the cylinder head; and   a timing drive for controlling a relative angular orientation of the crankshaft and the at least one camshaft, the timing drive including:
 a rotatable device operatively engaged with the crankshaft and the camshafts; wherein the rotatable device is one of a chain or a belt; 
 a tensioner arm pivotably secured to one of the cylinder block and the cylinder head and configured to direct the rotatable device; 
 a tensioner assembly comprising:
 a tensioner body having a fastener opening and defining a cavity with a plunger opening; 
 a plunger disposed in the cavity; 
 a removable pin restraining the plunger in the cavity, wherein the plunger is configured to be biased out of the plunger opening when the pin is removed; and 
 a protuberance extending outward from the tensioner body and adapted to receive an applied torque; 
 wherein the tensioner body is pivotably secured at the fastener opening to the cylinder block adjacent to the tensioner arm and is configured to pivot relative to the cylinder block toward the tensioner arm in response to a predetermined torque applied to the protuberance such that the tensioner applies a predetermined load to the rotatable device via the tensioner arm. 
 
   
     
     
         9 . The engine assembly of  claim 8 , wherein the tensioner body includes a slot extending through the tensioner body with the protuberance between the fastener opening and the slot, and further comprising:
 a locking bolt secured to the cylinder block and extending through the slot; wherein the locking bolt interferes with the tensioner body at an end of the slot to limit a range of motion of the tensioner body in response to the torque applied to the protuberance.   
     
     
         10 . The engine assembly of  claim 9 , wherein:
 a first flange extends in a first direction from the tensioner body;   the fastener opening is in the first flange;   a second flange extends in a second direction from the tensioner body opposite to the first direction; and   the slot is in the second flange.   
     
     
         11 . The engine assembly of  claim 8 , wherein the protuberance extends from an outer side of the tensioner body away from the cylinder block; and wherein an inner side of the tensioner body confronting the cylinder block is generally planar. 
     
     
         12 . The engine assembly of  claim 8 , wherein the tensioner arm has an outer surface facing the tensioner;
 wherein a distal end of the plunger has a convex distal surface configured to be engaged with the outer surface of the tensioner arm when the tensioner body is pivoted toward the tensioner arm in response to the predetermined torque applied to the protuberance; and   wherein the outer surface of the tensioner arm is curved.   
     
     
         13 . The engine assembly of  claim 12 , wherein the outer surface of the tensioner arm and the distal surface of the plunger are both convex. 
     
     
         14 . A method of assembling an engine timing drive, the method comprising:
 applying a predetermined torque to a protuberance of a tensioner that is pivotably mounted to a cylinder block to rotate the tensioner toward a rotatable device such that the tensioner applies a predetermined load to the rotatable device;   wherein the rotatable device is one of a chain or a belt placed around a crankshaft sprocket and around at least one camshaft phaser;   tightening a bolt securing the at least one camshaft phaser to the camshaft;   removing the predetermined torque from the protuberance of the tensioner; and   tightening a locking bolt to secure the tensioner to the cylinder block.   
     
     
         15 . The method of  claim 14 , further comprising:
 releasing a locking pin on the tensioner such that a plunger of the tensioner is biased toward the rotatable device.   
     
     
         16 . The method of  claim 14 , further comprising:
 prior to applying the predetermined torque, mounting the tensioner to the cylinder block with a shoulder bolt such that the tensioner pivots about the shoulder bolt when the predetermined torque is applied.   
     
     
         17 . The method of  claim 14 , further comprising:
 prior to applying the predetermined torque and prior to tightening the locking bolt, extending the locking bolt through a slot in the tensioner into the cylinder block; and   wherein the locking bolt abuts an end of the slot when the predetermined torque is applied.   
     
     
         18 . The method of  claim 14 , further comprising:
 prior to applying the predetermined torque, placing the rotatable device around the crankshaft sprocket and the at least one camshaft phaser.   
     
     
         19 . The method of  claim 17 , further comprising:
 prior to applying the predetermined torque, locking the crankshaft at a predetermined angular position relative to the cylinder block such that the crankshaft remains at the angular position when the predetermined torque is applied.   
     
     
         20 . The method of  claim 17 , further comprising:
 prior to applying the predetermined torque, locking the camshaft at a predetermined position relative to a cylinder head mounted on the cylinder block to prevent rotation of the at least one camshaft phaser relative to the cylinder block.