WO1994025332A1

WO1994025332A1 - Shock absorbing seat support post for bicycles and other pedal-powered contrivances

Info

Publication number: WO1994025332A1
Application number: PCT/CA1994/000200
Authority: WO
Inventors: Raymond D. Campbell
Original assignee: Campbell Raymond D
Priority date: 1993-04-28
Filing date: 1994-04-27
Publication date: 1994-11-10
Also published as: AU6533094A; TW258704B; CA2095645A1

Abstract

There is provided a new and useful shock absorbing support post for a seat comprising a tubular member (12) having top (14) and bottom (16) ends, shock absorbing means (22) within the tubular member (12), an elongated tubular stem (36) within and freely slidable relative to the tubular member (12), an upper end of the stem extending outwardly of the tubular member, a first centering slider (38) within the tubular member (12), the slider (38) engaging on a lower side thereof a top of the shock absorbing means (22) and engaging on the top thereof the bottom of the stem (36), a second centering slider (40) within the tubular member (12) adjacent the top end (14) thereof and through which the stem (36) passes, whereby the first (38) and second (40) sliders substantially prevent contact between the stem (36) and the tubular member (12), and a pair of longitudinally extending slots (42) in opposite sides of the stem (36) and a mating keypin (46) passing through the slots (42) and through opposite sides of the tubular member (12), and wherein the keypin (46) and slots (42) are positioned such that a lower end of the slots (42) brings up against the keypin (46) to thereby prevent the stem (36) from exiting the tubular member (12) and to maintain in combination with the shock absorber (22) a predetermined resting force on the shock absorber (22).

Description

TITLE OF THE INVENTION

SHOCK ABSORBING SEAT SUPPORT POST FOR BICYCLES AND OTHER PEDAL-POWERED CONTRIVANCES

FIELD OF THE INVENTION

This application relates to shock absorbing support posts for seats. One preferred application of the present invention is with bicycle seats.

BACKGROUND OF THE INVENTION

While the shock absorbing support post of the present invention can be incorporated into a variety of vehicles for recreational and other uses, the invention is particularly applicable to bicycles, and it will be primarily described in that context.

Bicycles even in modern configurations have been widely used for a great many years. More recently an increase in awareness of bicycling as an aid in maintaining physical fitness and the response of authorities in providing pathways specifically constructed and/or set aside for bicycling have led to a very strong resurgence in the sport. This in turn has led to an increase in development of types of bicycles and of accessories and equipment for use with and/or on bicycles.

An area which has not received a great deal of attention or in which development has not led to major improvement is bicycle seating. Particularly for recreational bicyclists who use their bicycles, for example, only on weekends, the lack of comfort of the bicycle seat remains a major and general cause of complains. It is likely that certain inherent aspects of bicycle seats which are dictated by the nature of bicycles

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SUBSTIT TE will remain troublesome to occasional riders. These include the limitations on size and shape of the seat.

An important contributor to discomfort for occasional bicycle riders is the jarring impact encountered in traversing obstacles such as dips or breaks in the surface upon which the bicycle is being ridden.

As well, in bicycle touring the addition to the bicycle of various filled baggage containers puts a substantial extra stress on frame and wheels which can result in breakdowns, particularly when traversing obstacles as above.

The present invention provides a shock absorbing support post for a bicycle seat or other seats as appropriate which markedly reduces the discomfort to the rider and the probability of breakdown of the bicycle arising out of the vertical movement of the bicycle in traversing obstacles, bumps and the like. In its preferred form the invention is configured to replace a conventional bicycle seat post without modification to the bicycle or the bicycle seat.

PRIOR ART

To date no practical system or device for absorbing shock in a bicycle seat post has been proposed. Canadian Patent 73,460, granted October, 1901, to Jarvis, provides a very complex seat with seat back for use on a style of bicycle in which the rider is in a semi-prone position. Provision is made for vertical oscillation of the seat and for cushioning of that movement by the use of a spring inserted into the bicycle frame. Canadian Patent 434,486, issued April 30, 1946, to Indian Motorcycle Company, illustrates an apparatus for cushioning a motorcycle seat.

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SUBSTITUTE SHEET Canadian Patent 477,755, issued October 16, 1951, to Gillespie, illustrates a shock absorbing apparatus for a tractor seat.

Canadian Patent 498,093, issued December 1, 1953, to General Tire & Rubber Company, illustrates a further shock absorbing apparatus for a tractor seat.

Canadian Patent 515,835, issued August 23, 1955, illustrates a further and rather complicated shock absorbing system for a tractor seat. Canadian Patent 982,468, issued January 27, 1976, to Showa Manufacturing Co., illustrates an apparatus which permits a bicycle seat to be lowered when stopped, as at an intersection, and raised when again starting off.

Canadian Patent 1,282,679 issued April 9, 1991 to Camberfield Manufacturing Limited, provides a much improved shock absorber. Nonetheless that device, which has common inventorship with the present, had several shortcomings.

The positioning of the post in the frame gives rise to a certain jamming effect, because the post sits in the bike frame at a 72° angle, top end towards rear of bike. In the pedalling action there are side-to-side pressures combined with the 72° angle to the rear. The seat is mounted behind the top dead centre (T.D.C.) of post. As a result a single key and keyway tends to inhibit the plunger from travelling smoothly through its 2 inches of possible movement.

None of the prior devices offer the simplicity or adaptability of the present invention.

BRIEF SUMMARY OF THE INVENTION

A shock absorbing seat support post has now been developed which serves to alleviate part of the discomfort which heretofore appertained to seats such as those used on bicycles. The device is compact and simple in construction

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SUBSTITUTE SHEET and can in most cases be substituted for conventional seat support posts with no modification required.

The device comprises a minimum of components and is very durable. Thus, the invention provides a shock absorbing support post for a seat comprising a tubular member having top and bottom ends, shock absorbing means within the tubular member, an elongated tubular stem within and freely slidable relative to the tubular member, an upper end of the stem extending outwardly of the tubular member, a first centering slider within the tubular member, the slider engaging on a lower side thereof a top of the shock absorbing means and engaging on the top thereof the bottom of the stem, a second centering slider within the tubular member adjacent the top end thereof and through which the stem passes, whereby the first and second sliders substantially prevent contact between the stem and .the tubular member, and a pair of longitudinally extending slots in opposite sides of the stem and a mating keypin passing through the slots and through opposite sides of the tubular member, and wherein the keypin and slots are positioned such that a lower end of the slots brings up against the keypin to thereby prevent the stem from exiting the tubular member and to maintain in combination with the shock absorber a predetermined resting force on the shock absorber.

BRIEF DESCRIPTION OF THE DRAWINGS

In drawings which illustrate embodiments of the invention,

FIGURE 1 is a side view partly in section of a support post according to the invention;

FIGURE 2 is a plan view in section of tubular member utilized in the invention with spacer bushing inside;

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T FIGURE 3 is a side view partly in section of a tubular stem utilized in the invention showing spacer bushing and flanged cap;

FIGURE 4 is a plan view in section of the top of the stem of Figure 3;

FIGURE 5 is a top plan view partly in section of the post of Figure 1;

FIGURE 6 is a longitudinal cross-section of a tubular stem utilized in the invention; FIGURE 7a to 7e illustrates a series of caps of different sizes for use in the invention;

FIGURE 8 is a further embodiment of the stem of Figure 3; and

FIGURE 9 is a bottom plan view of the invention. While the invention will be described in conjunction with illustrated embodiments, it will be understood that it is not intended to limit the invention to such embodiments. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following description, similar features in the drawings have been given similar reference numerals. The support post 10 includes a tubular member 12 having an upper or top end 14 and a lower or bottom end 16.

Member 12 is preferably constructed of cold drawn anodized aluminium.

The bottom 16 of tube 12 is preferably threaded as at 18 and is closed by a correspondingly threaded closing plug 20.

A shock absorbing means which in Figure 1 comprises compression spring 22 may sit directly on top 24 of plug 20. However, in a preferred embodiment an

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SUBSTITUTE SHEET adjustment screw 26 is provided passing through a threaded bore in threaded plug 20. Adjustment screw 26 springs up against a lower slider 28 upon which spring 22 is seated by means of the centering seat 30. Thus, changing the position of adjustment screw 26 in threaded plug 20 will correspondingly change the position of the bottom end 32 of spring 22 in tubular member 12.

In a preferred embodiment the shock absorbing means includes the polymer dampener 34 of substantially cylindrical configuration which in the embodiment which lacks adjustment screw 26 may be positioned either above or below lower slider 28. Where the adjustment screw 26 is present, the dampener 34 will sit on top of lower slider 28. A tubular plunger, piston or stem 36 is located for freely sliding movement within tubular member 12. Stem 36 is preferably seated on a first slider 38, an opposite side of slider 38 centering the shock absorber 22. Stem 36 then passes through a second slider 40 which is fixed adjacent top 14 of tubular member 12.

The combination of the first and second sliders and the lower slider then serve to maintain a spacing between the tubular member 12 and stem 36 and to also prevent wearing contact between shock absorber 22 and tubular member 12.

Lateral stability of stem 36, proper positioning of stem 36 in tubular member 12 and predetermined resting tension on shock absorber 22 is maintained by a slot or keyway and keypin arrangement. Thus, the stem 36 includes slots 42 extending longitudinally therein to a slot bottom 44. In the preferred case the slots 42 extend from the top of stem 36.

A keypin 46 extends through slots 42 and through openings 48 provided for the purpose in tubular member 12. Preferably, the keypin 46 also passes through openings 50 of the second or top slider 40.

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SUBSTITUTE SHEET As a rider passes over rough terrain and the stem 36 moves up and down against the shock absorber 22, substantial strength and stability is gained by the arrangement just described. Further strength and stability is derived from a top cap 52 which sits over the top 14 of tubular member 12. As illustrated in Figure 7a to 7e, the cap 52 can be varied in size to accommodate different sizes of tubular member 12. The differing sizes for tubular member 12 are necessitated by differing cycle frame sizes. By means of the differing cap sizes, a variety of tubular member 12 sizes can be used with a single size of stem 36.

It is highly preferred that the keypin 46 also extend through openings 54 in cap 52. With respect to Figure 3, a second cap 56 is illustrated on stem 36 and which can be adapted to different saddle mounts. A flange 58 is useful in limiting the travel of the seat mounting bracket down stem 36. As well, the dust sealing bellows 60 can be conveniently positioned by means of flange 58.

Figure 8 illustrates another embodiment of the top of the stem 36 in which a pin 62 is utilizes to maintain the position of the cap 56.

As noted briefly in the prior art discussion above, because of the positioning of the support post at an angle to the vertical when in use, very substantial stress is placed on the arrangement at the point of entry of the stem 36 into the tubular member 12. The present arrangement, particularly having in mind the top or second slider and the top cap, serves to remove a substantial amount of that stress from specific points on the components and to distribute it more evenly. As well, the arrangement of centering sliders by substantially removing contact between stem 36 and tubular member 12 and substantially reducing contact between shock absorber 22

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Of particular note in respect of second or top slider 40, the slider sits within the tubular member 36 with the wings 57 extending through slots 42. The keypin 46 passes through opening 59 which is partially in the wings 57, so that the keypin 46, which is preferably steel, does not impact on the edges of slots 42.

The sliders are preferably of Delrin ™. The sliding action between Delrin and the aluminium of tubular member 12 creates very little wear.

While shock absorber 22 is preferably a coil spring or combination of coil spring with polymer dampener, it is also contemplated that a pair of springs be utilized which have differing compression forces to accomplish a desired dampening effect.

A typical single spring 22 is about 5 inches long, has about 24 coils and has an outside diameter of about 0.835 inches. As will be evident from the above discussion, the stem 36 will be prevented from being withdrawn from tubular member 12 because the bottom 44 of slots 42 will bring up against the keypin 46.

As well, the keypin and keyway or slot arrangement will prevent rotation of stem 36 and tubular member 12 to enhance stability.

Finally, the setting of the rest tension by means of threaded plug 20 or the combination of adjustment screw

26 with lower slider 28 will ensure that there is no noticeable downward movement of the seat when a person mounts.

Typically the tubular member 12 would be about 10.75 inches long and the stem 36 about 8 inches.

In a typical case the maximum travel of the stem 36 will be about 2 inches. It is preferable that a substantial length of stem 36 remain in the tubular member

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SUBSTITUTE SHEET 12 as compared with the amount of stem 36 which is outside of the tubular member, in order to reduce the levering effect.

It is highly preferable that the kingpin 46 and slots 42 be oriented in the front and back direction of a cycle on which the seat is mounted. That arrangement provides maximum strength because additional strength is obtained from that positioning of the preferably steel pin 46. In order to maintain the integrity of the top of the stem 36 when seat hardware is clamped onto it, a spacer bushing 64 may be force-fit into the top of stem 36.

Thus it is apparent that there has been provided in accordance with the invention a shock absorbing seat support post for a bicycle or the like that fully satisfies the objects, aims and advantages set forth above. While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications and variations as fall within the spirit and broad scope of the invention.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A shock absorbing support post for a seat comprising: a tubular member having top and bottom ends; shock absorbing means within said tubular member; an elongated tubular stem within and freely slidable relative to said tubular member, an upper end of said stem extending outwardly of said tubular member; a first centering slider within said tubular member, said slider engaging on a lower side thereof a top of said shock absorbing means and engaging on the top thereof the bottom of said stem; a second centering slider within said tubular member adjacent the top end thereof and through which said stem passes; whereby said first and second sliders substantially prevent contact between said stem and said tubular member; and a pair of longitudinally extending slots in opposite sides of said stem and a mating keypin passing through said slots and through opposite sides of said tubular member; and wherein said keypin and slots are positioned such that a lower end of said slots brings up against said keypin to thereby prevent said stem from exiting said tubular member and to maintain in combination with said shock absorber a predetermined resting force on said shock absorber.

2. The support post of claim 1 wherein said shock absorbing means is a compression spring.

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SUBSTITUTE SHEET

3. The support post of claim 2 wherein said shock absorbing means comprises in addition to said compression spring a polymer dampener.

4. The support post of claim 1 including a threaded plug in threaded engagement with the interior of said tubular member at the bottom of said tubular member.

5. The support post of claim 4 including a lower slider engaging on a top side thereof said shock absorbing means and on a lower side thereof said threaded plug.

6. The support post of claim 5 including an adjustment screw extending through and in threaded engagement with a bore in said threaded plug and engaging at its upper end a lower side of said lower slider, whereby adjustment of the position of said adjusting screw will cause a corresponding adjustment in the position of said lower slider and so an adjustment of the rest tension on said shock absorber.

7. The support post of claim 5 wherein said lower slider is in centering engagement with said shock absorber whereby said first slider and said lower slider substantially prevent wearing contact between said shock absorber and said tubular member.

8. The support post of claim 5 wherein said shock absorbing means comprises a compression spring adjacent said first centering slider and a polymer dampener between said spring and said lower slider.

9. The support post of claim 5 wherein said shock absorbing means comprises a compression spring between said first centering slider and said lower slider, and a polymer dampener between said lower slider and said threaded plug.

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10. The shock absorbing support post of claim 1 including a cap over an upper end of said tubular member through which said stem passes.

11. The support post of claim 10 wherein said keypin also passes through said cap.

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