Mid-arm torsion spring in a switchable roller finger follower

Abstract

A compact switchable roller finger follower having an inner arm and outer arm for a Type II valve train is described. The compact switchable roller finger follower has its widest portion at a mid-arm position. One or more torsion springs provide a restoring force to urge the inner arm into a nested position in the upper arm in which position the inner arm may be locked to the outer arm so that a cam lobe profile is transferred into valve motion. At least one of the torsion springs is located at a mid-arm position.

What is claimed is: 
     
         1 . A switchable roller finger follower comprising;
 an outer arm;   an inner arm rotatably connected to the outer arm;   a first torsion spring positioned at a mid-arm location on a first side of the outer arm; and   a second torsion spring positioned at a mid-arm location on a second side of the outer arm, the second side being opposite the first side.   
     
     
         2 . The switchable roller finger follower as recited in  claim 1  wherein the inner arm is rotatably connected to the outer arm by a pivot shaft. 
     
     
         3 . The switchable roller finger follower as recited in  claim 1  further comprising a third torsion spring. 
     
     
         4 . The switchable roller finger follower as recited in  claim 3  wherein the third torsion spring is situated around a pivot shaft. 
     
     
         5 . The switchable roller finger follower as recited in  claim 1  wherein the outer arm has two bosses that extend outward from the outer arm body at a mid-arm position and one of the two bosses is located on one side of the outer arm body and the other of the two bosses is located on a second, opposed side of the outer arm body. 
     
     
         6 . The switchable roller finger follower as recited in  claim 5  wherein a coil of the first torsion spring is supported by one of the two bosses and a coil of the second torsion spring is supported by the second of the two bosses. 
     
     
         7 . The switchable roller finger follower as recited in  claim 1  wherein the inner arm has two holes situated on opposite sides of the inner arm and the two holes are configured to accept a Z-stop pin. 
     
     
         8 . The switchable roller finger follower as recited in  claim 7  wherein an upper end of the first torsion spring engages with a top surface of the outer arm and a lower end of the first torsion spring engages with the Z-stop pin. 
     
     
         9 . The switchable roller finger follower as recited in  claim 8  wherein an upper end of the second torsion spring engages with a top surface of the outer arm and a lower end of the second torsion spring engages with the Z-stop pin. 
     
     
         10 . A switchable roller finger follower comprising;
 an outer arm;   an inner arm rotatably connected to the outer arm; and   a torsion spring, wherein the torsion spring has a first coiled section positioned at a mid-arm location on a first side of the outer arm and a second coiled section positioned at a mid-arm location on a second side of the outer arm, the second side being opposite the first side.   
     
     
         11 . The switchable roller finger follower as recited in  claim 10  wherein the inner arm is rotatably connected to the outer arm by a pivot shaft. 
     
     
         12 . The switchable roller finger follower as recited in  claim 10  further comprising a third torsion spring. 
     
     
         13 . The switchable roller finger follower as recited in  claim 12  wherein the third torsion spring is situated around a pivot shaft. 
     
     
         14 . The switchable roller finger follower as recited in  claim 10  wherein the outer arm has two bosses that extend outward from the outer arm body at a mid-arm position and one of the two bosses is located on one side of the outer arm body and the other of the two bosses is located on a second, opposed side of the outer arm body. 
     
     
         15 . The switchable roller finger follower as recited in  claim 14  wherein the first coil of the torsion spring is supported by one of the two bosses and the second coil of the torsion spring is supported by the other of the two bosses. 
     
     
         16 . The switchable roller finger follower as recited in  claim 10  wherein the inner arm has two holes situated on opposite sides of the inner arm and the two holes are configured to accept a Z-stop pin. 
     
     
         17 . The switchable roller finger follower as recited in  claim 16  wherein a connecting section of the torsion spring located between the first coil and the second coil engages with a top surface of the outer arm and a lower end of the torsion spring engages with the Z-stop pin. 
     
     
         18 . The switchable roller finger follower as recited in  claim 16  wherein a connection section of the torsion spring located between the first coil and the second coil engages with the inner arm and an upper end of the torsion spring engages with the upper arm. 
     
     
         19 . A switchable roller finger follower comprising;
 an outer arm;   an inner arm rotatably connected to the outer arm; and   a torsion spring; wherein the widest portion of the switchable roller finger follower is located in a mid-arm location.   
     
     
         20 . The switchable roller finger follower as recited in  claim 19  wherein the switchable roller finger follower is for a Type II valve train.