1. Field of the Invention
The invention pertains to the field of tensioners. More particularly, the invention pertains to a tensioner with a ratcheting device.
2. Description of the Related Art
Blade tensioners are commonly used to control a chain or belt where load fluctuations are not so severe as to over flex the spring or springs. A ratchet with backlash is added to tensioners to limit the effective backward or untensioned travel of a tensioning device.
Prior art
A bracket 417 is provided for mounting the blade tensioner 410 in an engine. Holes 418 and 419 are formed in the bracket 417, and mounting bolts are inserted into these holes 418 and 419. A sliding face 416 contacts the distal portion of the blade shoe 411 and permits sliding. The slide face 416 is formed on the distal portion of the bracket 417. A pin 420 supports the proximal portion 413 of the blade shoe 411 so that it may move in either direction. The pin 420 is secured on the bracket 417.
One example of a tensioner that uses a ratchet device is shown in prior art
Prior art
Prior art
The prior art does not show an adequate means of adding a ratchet device to a blade tensioner.
A blade tensioner that imparts tension to a chain that drivingly connects a driven shaft to a driving shaft in an engine. The blade tensioner has a blade shoe with an accurately curved chain sliding face, a proximal end pivotally attached to a pivot pin of a bracket and a distal end that receives a ratchet rod. The distal end of the blade shoe slides along a first side of a sliding surface, which may be part of the bracket. The ratchet rod has a first end pivotally attached to the distal end of the shoe and a second end with a length having a plurality of teeth having a length. A spring clip receives the second end of the ratchet rod and has an edge for abutting or engaging the teeth of the ratchet rod. The spring clip biases the ratchet rod on the side opposite the length having a plurality of teeth so that the teeth of the ratchet rod engage with the edge of the spring clip. The spring clip is slidable along the second side of the sliding surface until the tab on the spring clip engages with a corresponding indentation on the second side of the sliding surface.
When the slack of the chain increases, the distal end of the blade shoe pivots away from the chain and slides on the first side of the sliding surface, forcing the ratchet rod toward the pivot pin. The toothed ramp of the ratchet rod is in contact with the edge of the spring clip and drags the spring clip on the second side of the sliding surface of the bracket along, until the spring clip tab mates with a corresponding indentation in the bracket. The slack of the chain may allow continued movement of the distal end of the blade shoe, ratcheting other teeth on the ratchet rod over the engaged edge of the spring clip.
Movement in the opposite direction is denied except for the intended backlash of the teeth of the ratchet rod as they abut the edge of the spring clip. Backlash is the allowed shuttle movement of the spring clip plus the length of one tooth of the plurality of teeth on the ratchet rod.
a shows a front view of the tensioner of the present invention without a chain.
The tensioner 501 and guide 520 are attached to the bracket 502. Referring to
Referring to
Pivotally attached to the bifurcated distal end 504b of the blade shoe 504 by pin 518 is a ratchet rod 514 with a first end 514a for receiving pin 518 and a second end 514b with ratchet teeth 516 along its length on at least one side as shown in
More specifically, as the distal end portion 504b of the blade shoe 504 moves towards the pivot pin 510, the spring force applied to the ratchet rod 514 by the curved side 512d of the spring clip 512 causes the edge of opening 512b at the bottom 512e of the U-shaped spring clip 512 to be forcefully engaged with the teeth 516 of ratchet rod 514. The resulting friction plus the angle of ramp 516a of teeth 516 in contact with edge 512b of the clip moves spring clip 512 in the direction of arrow 550, to the limit allowed by the forced engagement of tab 512a with the edge of the indentation in the outer portion 502e of the bracket. The distance between the bottom 512e of spring clip 512 and the pivot pin end of inner ramp surface 502d of bracket 502 determines one element of backlash of the tensioner. Additional movement of the distal end portion of the blade shoe 504 and companion ratchet rod 514 in the direction of arrow 550 would cause sliding between ramp 516a of the ratchet rod teeth 516 and the spring clip edge 512b ratcheting from tooth to tooth 516. Tooth length is the determinate of the second element of backlash of the tensioner. Backlash is the sum of the two elements and is the functional limit of the movement allowed in the direction opposite of arrow 550.
When the slack in the chain 500 increases, or the tension in the chain decreases, as shown in
When the slack on the chain 500 decreases or the load on the chain increases, the force of the chain 500 compresses the blade shoe 504, and the distal end portion 504b of the blade shoe 504 slides on the inner ramp surface 502d of the bent portion of the bracket 502 and away form the pivot pin 510 in a direction opposite of arrow 550. As the distal end portion 504b slides on the inner ramp surface 502d of bracket 502, the spring clip 512 moves a distance up the outer surface 502e of the bent portion of bracket 502 until the bottom 512e of U-shaped clip 512 abuts with the end of surface 502e and stops. Ratchet 514, however, continues to move with the blade shoe, by tooth 516 sliding in engagement with edge of opening 512b at the bottom 512e of U-shaped clip 512 until the blunt edge of tooth 516 at the end of ramp 516a abuts the bottom 512e and is stopped. This limited motion is the backlash.
Pin 508 is present to maintain the tensioner in a fixed shipping/installation position.
While a spring clip 512 that is U-shaped is the preferred shape for the clip, other shapes performing the same functions may also be used.
The function of the bracket 502 may be achieved by protrusions on the engine block.
Accordingly, it is to be understood that the embodiments of the invention herein described are merely illustrative of the application of the principles of the invention. Reference herein to details of the illustrated embodiments is not intended to limit the scope of the claims, which themselves recite those features regarded as essential to the invention.
Number | Name | Date | Kind |
---|---|---|---|
3426606 | Hopkins | Feb 1969 | A |
3490302 | Turner et al. | Jan 1970 | A |
3830114 | Daines | Aug 1974 | A |
4395251 | King et al. | Jul 1983 | A |
4921472 | Young | May 1990 | A |
5152552 | Ikegaya | Oct 1992 | A |
5797818 | Young | Aug 1998 | A |
5967921 | Simpson et al. | Oct 1999 | A |
6110063 | Okabe et al. | Aug 2000 | A |
6120402 | Preston et al. | Sep 2000 | A |
6193622 | Cressman et al. | Feb 2001 | B1 |
6238311 | Cutting | May 2001 | B1 |
6244981 | Simpson | Jun 2001 | B1 |
6447416 | Jacques et al. | Sep 2002 | B1 |
6478703 | Suzuki | Nov 2002 | B2 |
6547684 | Kurohata | Apr 2003 | B2 |
6612951 | Kurohata | Sep 2003 | B2 |
6623391 | Young et al. | Sep 2003 | B2 |
7338399 | Garbagnati | Mar 2008 | B2 |
Number | Date | Country |
---|---|---|
2550639 | May 1977 | DE |
0581219 | Feb 1994 | EP |
0867600 | Sep 1998 | EP |
1096174 | May 2001 | EP |
1358841 | Apr 1964 | FR |
62188812 | Aug 1987 | JP |
63062946 | Mar 1988 | JP |
08226503 | Sep 1996 | JP |
10002386 | Jan 1998 | JP |
2000-136861 | May 2000 | JP |
2001208151 | Aug 2001 | JP |
2004044749 | Feb 2004 | JP |
Number | Date | Country | |
---|---|---|---|
20060234819 A1 | Oct 2006 | US |