The present invention relates generally to hinges and more particularly to a hinge structure which includes bearing units, such as ball-bearing units located between adjacent knuckles of the hinge leaves to provide for both smooth operation and load support.
On residential and commercial buildings, doors are conveniently hung for swinging operation about a vertical axis of butt hinges or the like. The size and the weight of such doors often tends to exert a considerable axial load or force component on the hinges as well as a horizontal or radial load component. If a conventional butt hinge is used, the results of these radial and axial loads is the creation of considerable friction between the adjacent engaged surfaces of the knuckles of the hinge, as well as between those portions of the knuckle bores which are in contact with the hinge pin or pintle. This friction hampers smooth operation and also produces wear. Applying grease or oil to these areas of contact may help to reduce the wear on the adjacent parts on a relatively small or light door, but is of little use in the case of a relatively large or heavy door, or a door which is subject to frequent opening and closing about the hinges.
It is also known in the art to use bearing units or the like disposed between the adjacent knuckles of a hinge to accommodate the axial or vertical load or force component, but the bearing units in use fail to accommodate the radial or horizontal component of force or load and were ineffective where heavy doors were being used. To overcome this problem of horizontal load, spacing and support bushings disposed between the knuckle bores and the pintle have been used. These also proved unsatisfactory for all situations as friction and resultant wear continued to occur in the areas where such bushings engage and rotate against surfaces of either the pintle or the knuckle bores.
The next step in the art was to employ bearing units which could accommodate to certain degrees both radial and axial loading. Two examples of this type of hinge can be found in U.S. Pat. Nos. 3,465,380 and 3,118,171. These designs while more effective than the prior construction still were subject to inherent problems. In this regard at least one race member included an annular groove defining both inner and outer peripheral shoulders which fix the relative radial position of the ball bearing elements. While the arrangement did not effect the ability of the bearing units to accommodate axial loads, performance under heavy radial or horizontal loading was not always satisfactory.
More specifically, with the above-discussed arrangement relative movement between the respective race members and the bearing units is restricted by the fixed orientation of the ball bearing in the groove. Accordingly, when radial load is applied, the ball bearings which accommodate the load are not loaded uniformly, that is to say that when a radial load is encountered only one-half of the ball units will accommodate the load while an axial or thrust force will load all of the bearing elements. Thus, due to the use of the groove for the balls and the lack of relative movement, these bearing elements which are not accommodating the vertical load directly will be forced into engagement with one of the groove shoulders. This tends to produce wear, unwanted noise and hamper smooth operation of the hinge.
To overcome the above-mentioned disadvantages of prior art hinge structures, a further hinge structure as fully described and claimed in U.S. Pat. No. 4,097,959, which issued on July 4, 1978, to the assignee of the present invention, was developed. The hinge structure of that invention included ball-bearing units having an axially outer and an axially inner race members and a train of bearing members mounted for movement therebetween. The respective race members are so constructed that the bearing unit can accommodate both vertical and horizontal loads, with uniform loading of the load supporting bearing elements being attained by provision of slight relative movement between the race members and the bearing elements. The present invention is an improvement over the design of said patent, the disclosure of which is incorporated herein by reference. As such, the present invention affords not only benefits from the above-mentioned type of operation, but in addition, includes bearing units which are concealed within the hinge knuckles for aesthetic purposes and to protect the bearing units from the collection of dirt and other deleterious substances. The employment of a concealed bearing necessitates the use of a pintle which is of a relatively small diameter, and the present invention accommodates this by providing an axial extension on each bearing unit to lend non-bending support to the hinge pintle.