GB2166796A

GB2166796A - Adjustable friction hinge

Info

Publication number: GB2166796A
Application number: GB08510406A
Authority: GB
Inventors: Robert H Bisbing
Original assignee: Southco Inc
Current assignee: Southco Inc
Priority date: 1984-11-08
Filing date: 1985-04-24
Publication date: 1986-05-14
Also published as: GB2166796B; DE3534128C2; DE3534128A1; GB8510406D0

Abstract

The hinge comprises first and second components (10, 20, 30) having knuckles (12, 22, 32) hinged together by a hinge pin (50) so that the first component can be rotated relative to the second components. Washers (41, 42) are interposed between the adjacent, relatively rotatable faces of the knuckles. The hinge pin has a head (53) at one end and a screw portion (51) at the other for engaging with respective endmost knuckles to consolidate the hinge. The hinge pin can be rotated to vary the forces of consolidation and the frictional resistance to operation of the hinge. The washers are made of a different plastics material from the knuckles and is chosen to provide substantially constant frictional resistance to relative movement of the knuckles. The hinge pin is made of the same material as the knuckles. <IMAGE>

Description

SPECIFICATION Adjustable friction hinge This invention relates to an adjustable friction hinge for a lid or cover or the like.

The invention is particularly concerned with a hinge which permits raising of a lid or cover and holds the lid or cover in the raised position.

A hinge in which the inside diametrai dimension of a middle knuckle is adjusted to increase or decrease the frictional resistance is shown in U.S. Patent No. 1,175,358.

A hinge in which the inside diametral dimensions of two spaced-apart knuckles are adjusted is shown in U.S. Patent No. 1,033,582.

A principle object of the present invention is to provide an adjustable friction hinge which is clean and neat in appearance and can be made small for use on furniture or articles used in the home, such for example, as the cover or lid of a record player.

This object is achieved by deriving friction from contact between washers and knuckles of the hinge under the force generated by a plastics torque-adjusting screw which is positioned on the pivot axis and functions also as the hinge pin, the washers and the knuckles being made of different plastics material chosen to provide substantially constant frictional resistance to relative movement of the knuckles.

Reference is made to the accompanying drawings, wherein: Figure 1 is a perspective view of a preferred form of three-knuckle hinge embodying the invention; Figure 2 is an exploded perspective view of the component parts of the hinge of Fig. 1; Figure 3 is a front view, partly in section, of the hinge of Figs. 1 and 2; Figure 4 is a view looking along the line 4-4 of Fig. 3; Figure 5 is a front view of a slightly modified form of the hinge; and Figure 6 is a view of a five-knuckle form of hinge according to the invention.

In the adjustable friction hinge shown, the desired friction is provided by the endwise contact of plastics washer-shaped surfaces 41 and 42 shown in Fig. 2 and positioned between the end surfaces 25, 15, 16 and 35 of the knuckles 22, 12, and 32 of hinge components 10, 20, and 30. The knuckles and washers are purposely made of a different plastics material. The force needed to provide the desired friction is generated by a torqueadjusting screw 50 which is positioned on the pivot axis of the hinge. The threaded end 51 of screw 50 is received within the internally threaded knuckle 32 of hinge component 30.

The other knuckles 22 and 12 are not threaded.

The purpose of providing washers or washer-shaped surfaces 41, 42 between the end surfaces 25, 15, 16, 35 of the plastics hinge knuckles 22, 12, 32 is to eliminate the squeaking noise which is commonly encountered whenever two identical materials are rubbed together. As is known, where two identical surface materials are in contact, the coefficient of static friction is usually much higher than the coefficient of dynamic friction.

The term "coefficient" is used to mean the ratio between the force requried to overcome friction and the force holding the two surfaces together. The coefficient of static friction is that percentage of the force holding the two surfaces together which must be applied to start a sliding motion. The coefficient of dynamic friction is that percentage of the force holding the two surfaces together which must be applied to continue the sliding motion.

When these two coefficients are widely different, as is the case where two identical surface materials are in contact with each other, the motion between the two surfaces is an intermittent stick-slip motion and results in a squeaking noise. However, with proper selection of different materials, the coefficients of static friction and dynamic friction are more nearly the same and squeaking is avoided.

In a preferred embodiment of the present application, the hinge components 10, 20, 30 are integral moulded components made of a plastics material known as polyacetal. Hinge component 20 comprises leaf 21, knuckle 22, and stud 23. Component 30 comprises leaf 31, knuckle 32, and stud 33. Hinge component 10 comprises leaf 11, knuckle 12, and studs 13, 14. The torque-adjusting screw 50 is also made of polyacetal. The washers 41, 42 are made of nylon. The only elements of the hinge assembly which are not made of plastics are the nuts 60, which are preferably made of steel.

Polyacetal is a suitable elastic and creepresistant plastics material. By making the screw of polyacetal, the screw acts as a spring. Once the head 53 of screw 50 has seated against the internal shoulder of knuckle 22, tightening of the screw draws the three knuckles together against the washers 41, 42.

Further tightening elongates the screw slightly with each increment of torque adjustment in the tightening direction. This results in a reasonable range of screw rotation through which torque adjustment can be performed. If the screw were made of a much stiffer material, such as steel, there would be a sudden bottoming out.

The stick-slip characteristic (which results when a material has widely different coefficients of static and dynamic friction) is used to advantage in the present application in the tightening of the plastics torque-adjusting screw 50. As the screw 50 is tightened, an axial force is generated between the screw threads 51 and the underside 52 of the head -53. This force causes frictional resistance to turning with respect both to the screw threads 51 and also with respect to the head 53. Since the material of the screw 50 and of the hinge components 10, 20, 30 are identi cal, all being polyacetal, the resistance to turn ing of the screw 50 provides a ratchet-like feel. It also provides a high resistance to acci dental loosening of the screw.

In a preferred form of the three-knuckle hinge of the present invention, illustrated in Figs. 1-4, the hinge leaf on one side of the pivot axis is split into two pieces, 21 and 31, rather than being one piece. This avoids the problem caused by normal production tolerances in trying to make an exact size-to-size fit between the washer faces. Although not presently preferred, it is possible to make the hinge with a one-piece leaf on each side of the pivot axis. Such a hinge is shown in Fig.

5 where leaf 120 is a one-piece leaf and takes the place of the two leaves 21 and 31.

In Fig. 6 the hinge assembly is shown as having five leaf components, two components 200 and 210 on one side of the pivot axis and three components 220, 230, and 250 on the other side. In the form shown in Fig. 6, the hinge assembly requries four nylon wash ers 241-244 for four pairs of mating surfaces between the five knuckles 222, 212, 252, 217, and 232. In comparison with the three leaf component assembly illustrated in Figs.

1-4, the five-leaf component assembly illustrated in Fig. 6 has double the friction torque, assuming the same degree of tightness of the adjusting screw.

Actually, the number of leaves could be any odd number. The number of leaves should be odd so that the head and the threads of the adjusting screw are positioned inside of knuckles which are integral parts of leaves lo cated on the same side of the hinge. If the screw head and screw threads are inside the knuckles of leaves located on opposite sides of the pivot axis, there would be the possibil ity of relative rotation between one end of the screw and one of the leaves during operation of the hinge, resulting in a possible change of torque adjustment.

Referring again to the three-leaf assembly illustrated in Figs. 1-4, the leaf 11 on one side of the axis is provided with a pair of integral studs 13 and 14, while leaves 21 and 31 on the opposite side of the pivot axis are each provided with a single stud identified 23 and 33 respectively. The studs 13, 14, 23 and 33 are moulded as an integral part of the plastics hinge leaf, and may preferably, but not necessarily be tubular or hollow as shown in section in Fig. 4. This is merely to decrease the weight of the studs.

When moulded, studs 13, 14, 23 and 33 are without external threads. The threads are formed when the nuts 60, which are prefera bly steel, are threaded onto the studs to secure the hinge to the paneis P1, P2.

In the drawing, the pivot pin 50 is shown as having a philips type head having a recess 54 for receiving a philips type pool. It will, of course, be understood that the head 53 of the screw could have other non-circular forms of recess.

Claims

1. An adjustable friction hinge comprising a first component on one side of the hinge axis having a leaf portion and at least one first knuckle projecting therefrom, a second component on the other side of the hinge axis having a leaf portion and at least a pair of spaced-apart second knuckles projecting therefrom, the first knuckle being positioned between the second knuckles, the knuckles having aligned bores for receiving a hinge pin, one of the second knuckles having a nonthreaded bore having an internal shoulder and the other second knuckle having an internallythreaded bore, the first and second components being formed of a first plastics material, a pair of washers positioned between respective ends of the first knuckle and the end of the adjacent second knuckle, the washers being formed of a second plastics material different from said first plastics material, the first and second materials being so selected that the difference between the coefficients of static and dynamic friction of said first and second plastics materials when in contact with each other is substantially less than where said first and second plastics materials are identical, the hinge pin being received in the bores of the knuckles and having a head at one end engaged with the internal shoulder of one of the second knuckles and a threaded portion at the other end engaged with the internally-threaded bore of the other second knuckle, the head having means for engaging an adjustable tool.

2. An adjustable friction hinge according to Claim 1, wherein the hinge pin is made of said first plastics material.

3. An adjustable friction hinge according to Claim 1 or 2, wherein the second component comprises two separate pieces each having as an integral part thereof a respective one of the second knuckles.

4. An adjustable friction hinge according to Claim 1, 2 or 3 comprising a plurality of first knuckles and the same number of second knuckles plus one with each first knuckle positioned between a pair of second knuckles, the endmost second knuckles being provided respectively with the internal shoulder and the internally-threaded bore and a washer of said second plastics material being located between each end of each first knuckle and the end of the adjacent second knuckle.

5. An adjustable friction hinge according to Claim 1, 2, 3 or 4, wherein the means for engaging an adjustment tool comprises a non circular recess in the head of the hinge pin.

6. An adjustable friction hinge according to any preceding claim, wherein said first plastics material is polyacetal and said second plastics material is nylon.

7. An adjustable friction hinge constructed substantially as herein described with reference to Figs. 1 to 4, Fig. 5 or Fig. 6 of the accompanying drawings.