Chain tensioner

• US 7,527,572 B2
• Filed: 08/27/2004
• Issued: 05/05/2009
• Est. Priority Date: 08/29/2003
• Status: Active Grant

• Current Assignee: NTN Corporation
• Original Assignee: NTN Corporation
• Inventors: Kitano, Satoshi, Sato, Seiji, Hayakawa, Hisashi, Izutsu, Tomoyoshi
• Primary Examiner(s): Siconolfi; Robert A
• Assistant Examiner(s): Irvin; Thomas W
• Application Number:
  US10/927,281
• Publication Number:
  US 20050049093A1
• Time in Patent Office: 1,712 Days
• Field of Search: 474/101, 474/109, 292/281, 292/261, 292/194, 292/230, 292/195, 292/198, 292/203, 292/210, 292/285, 292/304, 292/341.17, 246/16
• US Class Current: 474/109
• CPC Class Codes: F16H 2007/0806 Compression coil springs
• CPC Class Codes: F16H 2007/0812 Fluid pressure
• CPC Class Codes: F16H 2007/0853 Ratchets
• CPC Class Codes: F16H 2007/0855 comprising a clip member engaging with the rack teeth
• CPC Class Codes: F16H 2007/0859 Check valves
• CPC Class Codes: F16H 2007/0878 Disabling during transport
• CPC Class Codes: F16H 7/0836 of the fluid and restriction type, e.g. dashpot
• CPC Class Codes: Y10T 24/45534 having connected leading edge and separated trailing arms
• CPC Class Codes: Y10T 292/1043 Swinging
• CPC Class Codes: Y10T 292/1063 Gravity actuated
• CPC Class Codes: Y10T 292/444 Swinging catch

Abstract

A chain tensioner includes a housing having a cylinder chamber. A plunger is slidably mounted in the cylinder chamber. A spring is mounted in the cylinder chamber to bias the plunger outwardly of the cylinder chamber. The plunger has a radially extending locking pin at its lower portion near its front end. The housing is formed with a pin hole extending substantially perpendicular to an axis of the cylinder chamber near the front end of the housing and under the cylinder chamber. The chain tensioner further includes a support pin inserted in the pin hole, and a locking lever supported on the support pin so as to be pivotable about the support pin. The locking lever can engage the locking pin when the plunger is sufficiently pushed into the cylinder chamber, thereby keeping the plunger pushed in the cylinder chamber.

Claims

1. A chain tensioner comprising:

a housing having a cylinder chamber;

a plunger slidably mounted in said cylinder chamber and defining a pressure chamber in said cylinder chamber in the back thereof;

a spring mounted in said cylinder chamber and biasing said plunger outwardly of said cylinder chamber;

wherein said housing is provided with an oil supply passage communicating with said cylinder chamber for supplying hydraulic oil into said pressure chamber to damp a force applied to said plunger against the force of said spring;

wherein said plunger has a radially extending locking pin at its lower portion near its front end;

wherein said housing includes a protrusion disposed below said cylinder chamber near the front end thereof and having first and second opposite sides disposed opposite each other in a transverse direction with respect to an axis of said cylinder chamber;

wherein a pin hole extends through said protrusion in said transverse direction with respect to the axis of said cylinder chamber from said first side to said second side of said protrusion;

wherein a support pin is inserted in said pin hole so as to extend through said protrusion below said cylinder chamber in said transverse direction with respect to the axis of said cylinder chamber, and a locking lever is supported on said support pin so as to be pivotable about said support pin, said locking lever being capable of engaging said locking pin when said plunger is sufficiently pushed into said cylinder chamber, thereby keeping said plunger pushed in said cylinder chamber;

wherein said locking lever comprises a pair of parallel side members each having a front end and a rear end, and pivotally supported at the rear ends thereof on said support pin, and a bar extending between and coupling the front ends of said side members so as to be substantially perpendicular to said side members; and

wherein said side members of said locking lever are disposed on said first and second opposite sides, respectively, of said protrusion.

2. The chain tensioner of claim 1, further comprising a backward movement restricting arrangement for preventing said plunger from moving toward an end wall of said cylinder chamber over a predetermined distance.

3. The chain tensioner of claim 1, wherein said side members of said locking lever are each formed with an elongated hole that is elongated in a longitudinal direction of said side members, and said support pin is received in said elongated holes, and wherein said locking lever comprises a U-shaped member.

4. The chain tensioner of claim 3, wherein said longitudinal direction of said side members of said locking lever is a direction extending from said support pin toward said bar of said locking lever.

5. The chain tensioner of claim 1, wherein said housing has a reduced-diameter portion at the front end thereof, and said protrusion protrudes radially downwardly from said reduced-diameter portion.

6. The chain tensioner of claim 1, wherein said housing has a main portion and, at the front end thereof, a reduced-diameter portion reduced in diameter relative to said main portion, and wherein said protrusion protrudes axially forwardly from said main portion and radially downwardly from said reduced-diameter portion.