CA2095645A1

CA2095645A1 - Cycle shock ii

Info

Publication number: CA2095645A1
Application number: CA 2095645
Authority: CA
Inventors: Raymond Denis Campbell
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-04-28
Filing date: 1993-04-28
Publication date: 1994-10-29
Also published as: TW258704B; AU6533094A; WO1994025332A1

Abstract

ABSTRACT OF THE DISCLOSURE

A shock absorbing seat support post for a bicycle or the like consists of a tubular member and an elongated tubular stem partially within and in sliding engagement with said tubular member; shock absorbing means within and towards bottom end of the tubular member; means of maintaining a predetermined resting force between the stem and the shock absorbing means. Metal to metal contact between tubular member and tubular stem is prevented by middle and bottom sliders made of delrin. In a preferred embodiment of the invention, the range of sliding movement is limited by two keways and horizontal key pin extending through: top cap; outer tube; piston and top slider. The key limits the rotation of the tubular stem while permitting reciprocating movement of the tubular stem relative to the tubular member.

Description

209564~

Thls application relates to ~hock absorblng ~upport post~
for seats. One preferred application of the preeent lnventlon is with bicycle ~eat~.

BACKGROUND OF THE INVENTION

While the shock absorbing support post of the present invention can be incorporated into a variety of vehicle~ for reereational and other uses, the invention i~ particularly applieable to bieycles, and it will be primarily deseribed in that eontext.
Bieyeles even in modern eonfigurations have been widely used for a great many year~. More recently an increase in awareness of bicycling as an aid in maintaining physical fitne~s and the response of authorities in providing pathways ~pecifically eonstructed and/or set a3ide for bicycling have led to a very strong resurgenee in the sport. This in turn has led to an inerease in development of types of bicycles and of accessories and - eq~ipment for use with and/or on bicyeles.
~ An area which has not reeeived a great deal of attention -~ or in whieh development has not led to major improvement is bieyele seat1ng. Partieularly for recreational bicyclists who use their bieyeles, for example, only on weekends, the lack of comfort of the bieycle seat remains a major and general cause of complaint.
It is likely that eertain inherent aspeets of bicyele eeat~ which are dictated by the nature of bieyele~ will remain trouble~ome to oeea~ional rider~. The~e inelude the limitations on -~ ~ize and shape of the seat.
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-~ 2 -209S64~

An important contributor to dlscomfort for occa~ional bicycle riders iB the jarring impact encountered in traverslng obstacles euch as dips or breaks in the ~urface 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 re~ult in breakdown~, 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, bump~ and the like. In its preferred form the invention is configured to replace a ~ 15 conventional bicycle seat post without modification to the bicycle i or the bicycle seat.

I PRIOR ART
I

i i 20 To date no practical system or device for absorbing shock 3-~ in a bicycle seat post has been proposed.
Canadian Patent 73,460, granted October, 1901, to Jarvis, provides a very complex eeat 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 ~pring ineerted into the bicycle frame.
Canadian Patent 434,486, issued April 30, 1946, to Indian -' 209S64~

Motorcycle Company, illustrate0 an apparatu~ for cuehioning a motorcycle seat.
Canadian Patent 477,755, ieeued October 16, 1951, to Gillespie, illustrates a shock ab~orbing apparatuq 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.
None of these prior devices offer the ~implicity 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 seat~ such`as those used on bicycles.
The device is compact and s1mple in construction and can in most cases be substituted for conventional seat support posts with no modiflcation roquired.
The device comprl~e~ a minimum of component~ and i8 very durable. Thus, the invention provides a shock absorbing ~upport ~-4 -~

~ ~ ;

209~64S

post for a eeat comprfslng a tubular member having top and bottom end, shock absorbing means within the tubular member, an elongated tubular stem partially within and in slidina enaaaement with ~aid tubular member, a first end of the ~tem engaging the middle ~lider and bottom of slider snugly fits into top of internal diameter of spring. Outward extension has flanged cap attached for universal fit. Shock absorbing means and a second end of the stem extending outwardly of the stem relative to the tubular member, and means for maintaining a predetermined resting force between the stem and the shock absorbing means. Two keyways and horizontal key pin extending through: top cap; outer-tube; piston; and top slider.
Predetermined resting force determined by knurled and threaded plug A. Tubular stem is not in sliding engagement with internal diameter of tube. Delrin sliders are the larger diameter and keep - 15 stem off inner wall with no metal to metal contact.
- In a preferred embodiment the invention compri~es a self-contained shock absorbing support post for replacing a shock absorbing support post ~ANADIAN 1282679 and US 5062617 patent and comprising a tubular member having top and bottom ends and adapted -~ 20 to be inserted bottom end first into and secured within a -~conventional tubular bicycle frame, shock absorbing means within and toward the bottom end of the tubular member, an elongated tubular stem partially within and in sliding engagement (with said 1~tubular member). Middle slider and bottom slider are in contact with tube inner wall not shaft. A fir~t end of the ~tem engaging the ~hock ab~orbing means and a ~econd end of ~he ~tem extending outwardly of the top end of the tubular member, different means from 1282679 limiting the range of sliding movement of the stem 20956~

relative to the tubular member, and means different for maintalning a predetermlned resting force between the stem and the ~hock absorbing means.

5BRIEF DESCRIPTION OF TNE DRAWING~

In drawings which illustrate embodiments of the invention, FIGUR8 1 is a side view cut away of a support post 10according to the invention;
FIGURE 2 is a plan view of tubular member utilized in the invention with spacer bushin~ inside;
FIGURE 3 is a side view of a tubular stem utilized in the invention showing spacer bushing and flanged cap.
:: 15FIGURE 4 i8 a plan view of the stem of FIGURE 3, cap bent over top of piston and flanged out at cap bottom;
FIGURE 6 new key pin stops side play and holds shaft in tube. pre-load of spring is from bottom adjustment;
FIGURE 7 and FIGURE 1 - A.B.C.D. illustrates one method 20of adjusting compression on the apparatus of the invention in the rest position. New bottom end adju~tment.
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 25contrary, it is intended to cover all alternatives, modifications and equivalents a~ may be included within the spirit and scope of ~the invention a~ defined by the appended claim~.

DETAILED DE8CRIPTION OF THE PRE~ERRED EMBODIMBNTn In the following description, eimilar features ln 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.
The tubular member 12 i5 preferable of cold drawn anodized aluminium. The bottom 16 of member 12 i~ preferably threaded inside as at 18.
A shock absorbing means 20 and 21 is located within the tubular member 12 and preferably toward the bottom 16 thereof or under the piston. Because of top cap 16 and top slider 54 this high stress area ha~ stress spread over inner and outer area instead of top of tube and back of stem.
A means of maintaining a space or tolerance between outer wall of piston and inner wall of tube. Delrin sliders 54, 55 and 56 maintain this space. 54 sits inside piston held in place by key pin. Function is to keep inside edges 59 of key ways from contacting steel pin. Delrin sliding on aluminium is a good match.
Steel on aluminium will cause excessive wear on aluminium. Steel pin 58 is necessary for strength and safety because of side to side pressures while peddling.
In its preferred form the shock absorbing means 20 comprising one spring 20 and one polymer dampener 21. Spring 20 at it~ lower end a4 fite over top of bottom ~lider 56 which sits on polymer Dampener which sits on wa~her which sits on threaded plug providing minlmal preload whlle secondary threaded plug provide~
adjustable preload. At the bottom 16 of tubular member 12, the 209S64~

~pr:Lng 20 i8 thu~ prevented from exltlng the tubular member 12 at the bottom 16.
In the preferred embodiment the ~pring 20 i~ a cylindrical compre~eion sprlng. The benefit of ~uch a ~pring i~
addressed later. In another alternative, a pair of springs having differing compression forces may be utilised one above the other to accomplish the same effect.
A typical single spring which has been found guitable i8 one about 5 inches long, having 24 coils and an outside diameter of about 0.835 inches. From group #3 through group #5 larger diameters of spring will be needed. Such a spring should be made of high quality piano wire.
Similarly, other forms of shock absorbers could be utilized, but it is generally considered that the least complicated and most economically attractive type i8 the spring.
A tubular plunger, piston or stem 26 has an upper or top end 28 and a lower or bottom end 30. The diameter of etem 26 is chosen to permit stem 26 to slide within a threaded top cap. Thus the bottom end 30 of stem 26 i9 inserted into member 12 to engage the middle 55 slider. Bottom end of slider 55 fits snugly into upper end of the spring 20.
Three functional requirements of these support post may be met by a single structural expedient. These functional aspects are as follows~
Fir~t, the ~tem 26 muYt be limited in upward movement.
Key pln and top ~lider 59 and 57, relative to the tubular member 12 to prevent withdrawal of the stem from the tube. The lower limit ; of movement of the ~tem 26 in normal u~e is preferably defined by 209S64~

a predetermined degree of compres~ion of the epring 10 and polymer dampener 21. Preload determined by bottom threaded plug.
Second, it is preferable that there be no or little noticeable movement of the seat when a person ~imply mounts or dismounts. Accordingly, it is desirable that such a degree of force be maintained on the shock absorber 20 in the rest (user dismounted) position that the normal mounting action will cause little movement of the shock absorber and hence of the seat. This i5 preferably achieved in the preferred spring usage by preventing the stem 26 froD rising sufficiently in the member 12 to allow complete relea~e of the spring 20. (*preload determined by bottom threaded plug). The stem is maintained in a rest position in which spring 20 remains compressed to a predetermined required extent, which may be adjustable for different rider weights. New bottom end adjustment enables rider to fine tune adjustments ~Figure 7 and Figure 1 - A,B,C,D.) Old top end spring adjustment CAN. PAT.
1282679 only allowed for large adjustments (3/8") at a time.
Third, the stem 26 should be restrained against rotation within the tubular member 12. This is required for good stability.
58 key pin and top slider 54 and 57.
Each of the above three objectives can be aahieved by utilizing 2 keyways and a key pin. Thus, 2 keyways are formed in the stem 26. In one preferred embodiment 2 keyways in the form of 2 slots 36 are formed in the tubular piston 26 to mate with the keypin 58. The keyways and keypin and top ~lider 54 and 57 combination prevents rotation of etem 26 relative to tubular member 12. As well the top slider 57 will abut against the end~ 40 of slot~ 56 to limit the upward movement of stem 26, stopping the ~ 9 knocking noise caused by a quick return to top.
The~e above objective~ achieved by 2 keywaye and a strong steel pin running horizontally through both keywaye. Pin ~urrounded with delrin ~lider to keep steel pin and aluminium from contact. Prevents rotation of stem. Limit~ upward movement of stem. Does not preload spring.
In use in a bicycle the tubular member 12 is slid into the tubular bicycle frame in the manner in which a seat support -~
post is conventionally so inserted. The level of the top 14 of the tubular member 12 would be set in accordance with the seat height preference of the individual rider. Conventionally, at least 2 1/2 times the outside diameter of the post should extend into the bicycle frame and that applies to the present case. A minimum insertion line i8 present for safety, on outer tube. ~ ~
Flange 42 ~page 2) will also provide a limit to the ~ -extent that seat can be slid onto ~tem 26 to thus prevent contact between the seat proper and the stem. Flanged aluminium cap. ~ -Once the tubular member 12 is secured in the bicycle - --frame, a bicycle seat is secured adjacent the top 28 (Fig. 3) of stem 26. ~-The preferred material for the tubular member 12 is cold drawn aluminium. The tubular member 12 in a typical embodiment would be about 10 3/4 inches long. Piston 8 inches long.
It is important to have more piston in tube than out of tube because of lever effect. Longer the lever out of tube the more pre~ure exerted by plston bottom on tube inner wall~ Where a epring shock absorber is utilized, the spring is preferably about 5 inches in length and with a compression force which will vary 209564~

depending on the particular u~e. For exampl~, u~e in an adult bicyclQ would require higher force than use in a child's bicycle.
The compression force is chosen to typically allow about a inches maximum travel for the stem 26.
The positioning of the upper end 44 of ~lot 36 is not important other than that it must allow for the required travel of stem 26. Xeyways 36 must face front and back of bicycle for maximum piston strength. The extent of travel will vary with spring strength but typically may be in the two inch range.
The stem 26 is preferably cold drawn aluminium.
Typically the stem 26 would have a length of about 8 inches. Five (5) different diameter~ for stems 26 would be necessary to cover 22 sizes of bicycles frames. "Explained in detail on page 1 of drawings."
Thus it is apparent that there has been provided in accordance with the invention shock absorbing support posts for seats 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.

- 209S6~S

Insert A
Canadian Patent 1282679 is~ued April 9, 1991, to Ray Campbell and assigned to Camberfield Manufacturing Limited.
This has proved to have sQveral flaw~ in de~ign. There is a jamming effect using a single keyway and key.
Because the post sits in the bike frame at a 72 angle, top end towards rear of bike. In the pedalling action there i9 side to side pressures combined with the 72 angle to the rear and the seat mounting behind the top dead centre (T.D.C.) of post, a single key and keyway stops plunger from travelling smoothly through its 2" of possible movement in each direction down and up.
Because of the smaIl inside diameter of the seat post, the size of the key is limited in depth to allow maximum material to be retained on plunger for strength necessary to support riders weight.
The key having to be so small leaves little material to , drill and thread the 6 mm x 8 mm cap screw necessary to adjust or ~ -~
preload tension spring ends up, stripping the threaded portion of -~
the key, allowing the seat to turn 360 horizontally or laterally.
Because the outslde diameter of the pIunger, and internal diameter of the tube, only allow for minimal clearance to allow smooth vertical movement, when fastened too tightly into bike frame, the outer tube 18 oqueezed and st~p~ plunger travel.

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Claims

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 with top and bottom sliders in sliding engagement with said inside diameter, a first end of said stem engaging delrin slider and said shock absorbing means and a second end of said stem extending outwardly of said tubular member;
means limiting the range of sliding movement of said stem relative to said tubular member; and means for maintaining a predetermined resting force between said stem and said shock absorbing means, said means comprising 2 longitudinally extending slots or key way having upper and lower ends in said stems and a mating keypin in said tubular member and wherein said keypin said keyways are positioned such that said lower end of keyways brings up against said keypin to thereby stop stem from exiting tube stem sliding movement of said stem at a point where stem has a fixed minimum of its length in tube.

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

3. The support post of claim 2 wherein said spring will cause polymer dampener to start compression when spring is close to full compression.

4. The support post of claim 1 wherein said shock absorbing means comprises a pair of springs in series relationship, one of which is of a lesser predetermined force and the other of a greater predetermined force.

5. The support post of claim 1 wherein said shock absorbing means is a spring slidable within said tubular member and wherein said tubular member includes stop means threaded plug preventing expulsion of said spring through said bottom end.

6. A threaded plug which stops spring from dropping out and also allows more or less spring compression by tightening or loosening.

7. A self-contained shock absorbing support post for replacing a conventional bicycle seat support post and comprising:
a tubular member having top and bottom ends and adapted to be inserted bottom end first into and secured within a conventional tubular bicycle frame;
shock absorbing means within and toward said bottom end of said tubular member;
an elongated tubular stem partially within and in sliding engagement with said member, a first end of said stem engaging said shock absorbing means and a second end of said stem extending outwardly of said top end of said tubular member for attachment to a conventional bicycle seat;
means limiting the range of sliding movement of said stem relative to said tubular member; and means for maintaining a predetermined resting force between said stem and said shock absorbing means, said means comprising two (2) longitudinally extending slots or keyways having upper and lower ends in said stem and a mating keypin in said tubular member and wherein said Keypin and said Keyways are positioned such that said lower end of said keyways brings up against said to thereby stop sliding movement of said stem at a point where said predetermined resting force exists between said shock absorbing means and said stem. (See Page 13 old patent.)

8. The support post of claim 10 including stop means on said stem to limit the extent of entry of said tubular member into said bicycle frame.

9. The support post of claim 11 wherein said comprises keyways adapted for relative sliding movement in said.

10. Top of support post threaded externally to accept top cap and threaded at bottom internal diameter to accept plug and adjustment screw.