Patent Application
20060022412
This invention relates to a seal for pins that connect two pivoting parts designed to keep dust away from a bushing for the pin, and to keep lubricating grease trapped for lubricating sliding side surfaces. In an exemplary application such as holding the rod end of a hydraulic cylinder to a bracket at the top of a loader bucket, the pin is generally held stationary, and the rod end will pivot on the pin as the bucket is tilted.
Such connecting pins will operate in dusty conditions and it is important for the life of the bushing that is used on the rod end to keep grit and dirt out, and also to keep grease, used as a lubricant, in place.
Excessive introduction of dirt in the pivoting parts causes wear and the need for replacement.
A rod end of a hydraulic cylinder is generally positioned between two side hub members and connects to the hubs with a cylindrical pin. Dust and dirt can get in along the sides of the rod end, as well as along the surfaces of the pin. The present invention provides for a seal that will prevent introduction of dust and dirt, and will also aid in maintaining a lubricant, such as grease, on the relatively moving parts.
The present invention relates to a seal structure that is used in connection with a cylindrical bore in a movable member that receive a pin, and wherein the pin and the surface of the bore must relatively rotate. Specifically, the seal is designed to operate between two surfaces of a bracket or support that flank or are positioned on opposite sides of the movable member, such as a rod end of an actuator, so that dust is kept away from the bushing by sealing along surfaces of the bracket on an annular line spaced outwardly from the pin, and also by sealing directly on the exterior surface of the pin.
The seal is an annular seal that has two sealing lips, one for sealing on the pin outer surface and one on the side surfaces of the bracket. The lips form a grease pocket between one of the side surfaces on the bracket supporting the rod end so that there is a supply of lubricant on the outer sides of the rod end while dust and dirt are excluded from the inner surface of the rod end. A bushing is normally used in the rod end for receiving the pin.
While a skid steer loader tilt cylinder connection pin is shown as an example of use, the present invention finds application where two members, one rotating or pivoting and the other stationary are held together with a pin that is greased. Other examples would be excavator boom pivot mountings, pivoting load arms on utility vehicles and the like.
Also the seal of the present invention has application on a rotating idler roller or sprocket on a stationary shaft and for roller seals for track idler rollers of a track driven vehicle.
In
The tilting plate has rod end attachment brackets 11 formed with spaced side plates or ears 12, which are spaced apart sufficiently to receive the rod end. And on the outer sides of these plates 12, 12 there are tubular hubs 14 that will receive ends of a connecting pin 16 used for connecting the rod end or eye 10 to the attachment plate 56. The pin 16 is held in one hub 14 with a suitable roll pin 15 to prevent rotation relative to the hubs 14 and the side plates 12. As the attachment plate 56 is tilted about the pins 55, it can be seen that the rod end 10 has to pivot on the pin 16.
The rod end or eye 10 has a bushing 18 on the interior thereof that receives the pin 16. The ends of the bushing 18 are set inwardly from side surfaces 19 of the rod. The surfaces 19 are closely spaced from and can actually rub against the inner surfaces 12A of the side ears or plates 12, as the attachment plate 56 is tilted.
The bushing 18 provides a low friction pin mounting, but the side surfaces 19 of the rod end slide against the inner surfaces 12A of the plates 12, and this also can result in wear.
The loader operates under conditions where dirt and dust will drop onto the rod end 10 and tend to get in between the surfaces 12A and the side surfaces 19 of the rod end. Also, dirt and dust can work in between the bore of the ears 14 and the side plates 12, and the pin 16, which is slightly smaller than the bore. To provide for a dust seal as well as providing for permitting grease to be retained between the surfaces 12A and 19, a seal 22 of the present invention is provided. As shown in
Each seal 22 has a metal support ring 21 that supports an elastomeric seal ring 23. The seal ring 23 has an annular first seal lip 24 that has an outer end or edge that resiliently engages and seals relative to the respective inside surfaces 12A of the two plates or ears 12. Each of the annular elastomeric seal rings 23 also has a resilient ring 41 having a second seal lip 26 that surrounds and resiliently rides against the outer surface of the pin 16 to seal the respective ends of the hubs 14 against dust coming into the bushing from the hubs.
The first seal lip 24 has an edge portion that rides against the adjacent surface 12A of the respective side plate 12 under a resilient force. Each seal 22, as shown, includes the elastomeric ring section 23 that has an outwardly tapered, annular flange 32. The outer edge of the flange forms the first seal lip 24. The support ring 21 of metal that supports the elastomeric ring 23 will press fit onto the respective end of the bushing 18 that protrudes beyond one of the cavities 36 formed in the rod end 10 to retain the seal in position.
The flange 32 is annular and tapers outwardly from the support ring and has resilience and length so a seal in maintained with the lip 24. The lip 24 will continue to seal even with a substantial amount of axial movement of the rod end relative to the side plates or ears 12.
The resilient annular second seal lip portion 26 on ring 41 that rides on the pin 16 has an internal diameter that is smaller than the outer diameter of the pin 16, so that the resilient second seal lip portion 26 is compressed and under some load as it rides on the pin to provide an adequate dust seal against dust or other materials entering axially along the outer surface of the pin. The second seal lip keeps dust and dirt away from the bushing. Also, the second seal lip 26 retains clean grease in the pin to bushing area and forms an annular pocket 43 that acts as a grease reservoir (see
The outwardly tapered flange 32, which includes the first seal lip 24, is also resilient (rubber, fluorocarbon or other elastomeric material), and as shown in
The inner resilient ring 42, which has the seal lip 26, and the flange 32 form a grease pocket 40, into which grease that is forced out along the bushing 18 and extruded past the seal lip portion 26 is held. The resilient ring 41 expands and lets grease enter into the pocket 40, as indicated by the arrow 42. This grease pocket 40 then provides some lubrication along the wall surface 12A that lubricates any moving or relatively rubbing parts between the side surfaces 19 of the rod end 10 and the side plates 12. Grease in the pocket 40 can also block dirt from entering the pocket 43, which dirt would work in between the pin 16 and the bushing 18 to cause wear.
The double seal, including the seal line of seal lip 24 against the adjacent surface 12A and the seal lip 26 against the outer surface of the pin 16, ensures that dust will not enter into the bushing. If the rod end shifts slightly from side to side, grease in the cavity 40 between the two sealing lips or regions 24 and 26 also helps to keep external contaminants from reaching the bushing surface. When the joint is greased through the grease fitting and passageway 20, the clean grease are will flow into the area between the two seals forming the cavity 40, and the old duty grease that is present in the cavity 40 between these lips is pushed outwardly past the lip 24 and along the side surfaces of the rod end, and the inner surfaces of side plates 12.
The rod end 10 having a seal 22 on each side, is easily installed because the seal lips will resiliently move out of the way for movement of the rod end into the position between the two sides plates 12.
The outer lip surface 44 is cylindrical and when the pin is horizontal, as dirt falls on the top side, the radius causes the dirt to tend to slide off in each direction, allowing gravity to cause the dirt to fall away and not enter into the pocket 40.
Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.
