GB2379951A

GB2379951A - Frictional restraint for telescopic tubes

Info

Publication number: GB2379951A
Application number: GB0122593A
Authority: GB
Inventors: Chien-Jen Huang
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-09-05
Filing date: 2001-09-19
Publication date: 2003-03-26
Anticipated expiration: 2021-09-19
Also published as: NL1018962C2; AU758345B1; GB2379951B; GB0122593D0

Abstract

A retaining and releasing mechanism adapted for use in a telescopic tube is equipped with an adjustment device 3 having a pair of case halves 30 that form a tubular case through which an adjustment rod 60 secured to a major tube 70 extends. The case of the adjustment device 3 is associated with a minor tube 80. The adjustment device 3 is frictionally mounted to the adjustment rod 60 by way of a main and a secondary retaining ring units 50, 51 and a plurality of restraint rings 52 that are obliquely mounted onto the adjustment rod 60 so as to frictionally hold the adjustment rod 60 in place and are controllably brought into a normal position with respect to the axis of the adjustment rod 60 for slidable adjustment of the adjustment device 3. The main and secondary restraining units 50, 51 and restraint rings 52 confined in the tubular case and divided into two groups by a compression spring 53 and are controlled by a spring biased urging plate 40 actuated by a button 82 exposed out of the minor tube 80 to permit the telescopic tube to be adjusted stagelessly.

Description

RETAINING AND RELEASING MECHANISM FOR A TELESCOPIC TUBE BACKGROUND OF THE INVENTION The present invention relates to retaining and releasing mechanism adapted for use in a telescopic tube. The retaining and releasing mechanism is equipped with an adjustment device having a pair of case halves that are separably engaged with each other to form a tubular case in which an adjustment rod extends therethrough. The case of the adjustment device is movably received in a major tube and is associated with a minor tube that is telescopically engaged with the tubular case.

The adjustment device is frictionally mounted to the adjustment rod by way of a main and a secondary retaining ring units and a plurality of restrain rings that are obliquely mounted onto the adjustment rod so as to frictionally hold the adjustment rod for fixing purpose and are controllably brought into a normal position with respect to the axis of the adjustment rod for slidable adjustment of the adjustment device, resulting in the telescopic extension or contraction of the minor tube with respect to the main tube. The main and secondary restraining units and restraint rings confined in the tubular case and divided into two groups by a compression spring and are controlled by a spring biased urging plate to permit the telescopic tube to be adjusted stagelessly.

There are two prior art adjustment structures illustrated in Figs. 1, 2 for use

in telescopic tubes. Referring first to Fig. 1, the main tube 10 contains a secondary tube 11 which is movable in the main tube 10. There are a plurality of equally distanced retaining holes 101 defined on the wall of the main tube 10. At the end of the secondary tube 11 is disposed a through hole 111 with a U-shaped retaining spnng 112 engaged with a pressing button 113 which is movably located in the through hole 111 and engaged with one properly selected retaining hole 101 of the main tube 10 to effect the adjustment of the length of the telescopic tube. To make further adjustment, the pressing button I ! 3 is pressed down to make the main tube free of restraint so as to permit the telescopic tube to be adjusted.

The disadvantage of the first prior art is that telescopic tube has a secondary tube 11 and the main tube 10 is provided with a plurality of retaining hole 101 spaced at equal distance, but the telescopic tube can not be adjusted in a stageless manner, causing the adjustment of the length of the telescopic tube in a limited way to be inconvenient and not suitable for all purposes.

Referring to Fig. 2, the second prior art structure is illustrated. It comprises a main tube 20 and a secondary tube 21 which is movably housed in the main tube 20. At the front end of the main tube 20 is disposed a locking section 22 having outer threads 222 and an internally tapered cap 23 having a tapered inner wall 231 is disposed around the secondary tube 21. A pair of semi-circular correspondingly

tapered retaining pieces 221 wrapped about the secondary tube 21 are gradually forced to grasp the secondary tube as the cap 23 having inner threads 232 is turned to moved inwardly or left. To operate in a reverse manner, the secondary tube 21 can be released for adjustment of the length of the telescopic tube.

There are a number of disadvantages associated with the second prior art structure given as below: 1. The locking section 22 and the internally tapered cap 23 are located outside the main and secondary tubes 20, 21, making the whole appearance of the structure not appealing to eyes.

2. The tapered retaining pieces 221 can not effectively hold the secondary tube 21 in place and the secondary tube 21 is easily withdrawn into the main tube 20 when accidentally pushed.

3. The secondary tube 21 is first adjusted to a proper length and then the cap 23 is locked against the locking section 22, the operation is tedious and not convenient relatively.

SUMMARY OF THE INVENTION Therefore, the primary object of the present invention is to provide a

retaining and releasing mechanism for a telescopic tube which can be adjusted in a stageless manner so as to permit a user to extend the telescopic tube in conformance to the height thereof, making its operation convenient and ready.

Another object of the present invention is to provide a retaining and releasing mechanism for a telescopic tube which adopts an off-center structure to effect finn positioning, preventing the telescopic tube from accidentally withdrawing in operation.

One further object of the present invention is to provide a retaining and releasing mechanism for a telescopic tube wherein an adjustment device and an adjustment rod are housed in a main tube and a secondary tube respectively in a concealing manner so as to make the whole structure appealing to eyes.

BRIEF DESCRIPTION OF THE DRAWINGS- Fig. 1 is a sectional diagram showing the operation of a first prior art; Fig. 2 is a sectional diagram showing the operation of a second prior art; Fig. 3 is a perspective diagram showing the exploded components thereof ; Fig. 4 is a sectional diagram showing the assembly thereof ; Fig. 5 is a diagram showing the adjustment operation of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to Fig. 3, the adjustment device 3 of the present invention is provided with a pair of case halves 30, an urging plate 40, a bias spring 45, a main retaining ring 50, a secondary retaining ring unit 51, a plurality of restraint rings 52, a compression spring 53 and an adjustment rod 60. The case halves 30 are symmetrically structured and each has a locking rod 31 and a receiving recess 32 at two opposite comers. thereof respectively. At the center of each case half 30 is disposed a longitudinal adjustment rod housing groove 33 in communication with a limiting cavity 34. Next and parallel to the housing groove 33 is a slide cavity 35 for slidably locating the urging plate 40. The front and rear end of each limiting cavity 34 is disposed a slant plane 341.

At the front end of the urging plate 40 is disposed a push head 41 and at the middle thereof is defined a stop section 42 and at the rear end is disposed a secondary limiting section 43 and a curved main limiting section 44. The main retaining unit 50 is made up of a limiting ring 501 and an elongated pressing stick 502 fixed to a summit of the limiting ring 501 having a stop hole 503 at the center thereof. At the front end of the pressing stick 502 is disposed a slightly bent driving projector

504 designed in conformance to the shape of main limiting section 44. The secondary retaining unit 51 is made up of a limiting ring 511 and a horizontally extended pressing stick 512 of a proper length which is integrally secured to the summit of the vertically placed limiting ring 511. A stop hole 513 is disposed at the center of the limiting ring 511. Each of the restraint rings 52 has a central friction limiting hole 521 which is slightly smaller than the stop holes 503,513 of the limiting ring 501 and the limiting ring 511.

The outer diameter of the adjüstment rod 60 is slightiy smaiier than Ihal of the friction limiting hole 521 of the restraint rings 52 and the length of the same is the same as that of the main tube 70.

In assembly, as shown in Fig. 4, the main retaining unit 50 and the secondary retaining unit 51 are respectively placed in the limiting cavity 34 of one of the two case halves 30 and the limiting rings 501,511 thereof abut against the slant planes 341 with the stop holes 503,513 obliquely out of alignment with the housing grooves 33. Then a pair of restraint rings 52 are respectively located in a slant manner against the limiting rings 501,511 with the friction limiting holes 521 in slant alignment with the stop holes 503,513. The compression spring 53 is place between the two opposite innermost restraint rings 52 with the ends of the compression spring 53-in abutment with the inner sides of the two restraint rings 52. Thereby the main

retaining unit 50 and the secondary retaining unit 51 are firmly retained in place in abutment against the slant planes 341 by way of the compression spnng 53. By pressing the pressing sticks 502,512, the limiting rings 501, 511 are forced to move toward each other inwardly, making the compression spring 53 compressed Then the urging plate 40 is placed in the slide cavity 35 with the main and secondary limiting section 44,43 extends over the slide cavity 35 and further into the limiting cavities 34. At then the bias spring 45 is housed in the slide cavity 35 with one end thereof abutting against the side wall of the slide cavity 35 and the other end abutting against the stop section 42 of the urging plate 40. Next, the other case half 30 is engaged with the case half 30 with the components put in place with the locking rods 31 engaged with the receiving recesses 32 to complete the assembly of the adjustment device 3.

Besides, the adjustment device 3 can be attached to the end of a minor tube 80 which is equipped with a linkage 81 engaged with the push head 41. The linkage 81 extends to the front end of the minor tube 80 and is coupled to a press button 82 of the minor tube 80. The adjustment rod 60 is inserted deep to the bottom of the major tube 70 which is firmly engaged with the minor tube 80 as a result of the insertion of the adjustment rod 60 receiving in the adjustment rod housing grooves 33 of the two engaged case halves 30 as shown in Fig. 5.

To make adjustment in operation, as illustrated in Fig. 5, the press button

82 only has to be pushed to transmit the external force by way of the linkage 81 to the push head 41, resulting in the dnving of the urging plate 40 to move inwardly. Accordingly the bias spring 45 is compressed. When the main and secondary limiting sections 44,43 slide to abut against the driving projector 504 of the main retaining unit 50 as well as the pressing stick 512 of the secondary retaining unit 51, the restraint rings 52 are brought into a vertical position so as to make the center line of stop holes 503,513 and all the friction limiting holes 521 come into alignment with

the axial line of the adjustment rod housing grooves 33. At the same time, the .. ousin (r g, () () V LAI L compression spring 53 is compressed by the restraint rings 52 brought into a position normal to the axis of the adjustment rod 60. Accordingly, the adjustment device 3 mounted onto the adjustment rod 60 is permitted to slide smoothly along the adjustment rod 60 as a result of the ring elements being brought into a normal position with respect to the axis of the adjustment rod 60 whereby the minor tube 80 can be partially pulled out of the major tube 70.

As an adjustment operation is completed, external forces are removed, the compression spring 45 resumes its normal non-operation state and the urging plate 40 is brought back to its original position The main retaining unit 50, the secondary retaining unit 51 and the multiple restraint rings 52 are urged by the resumed compression spring 53 back to

their non-operational positions with the center lines of the stop holes 503,513 and the friction limiting holes 521 out of the alignment with respect to the axial direction of the housing grooves 33, i. e. , the ring elements mounted to the adjustment rod 60 are positioned in an oblique manner with respect to the adjustment rod 60. The slantly located restraint rings 52 permit the limiting holes 521 thereof to hold the adjustment rod 60 by frictional force in position. The more restraint rings 52 are adopted, the more firmly the adjustment device 3 is held by the restraint rings 52 not to slide on the adjustment rod 60, so is the minor tube 80 retained in position in use.

It can be clearly seen that the present invention has the following advantages in operation: 1. Such a structure permits of stageless adjustment of the tube so as to extend the tube best suit to the physical size of a user.

2. The use of off-set restraint rings can firmly hold the minor tube 80 in a more secure manner, preventing the tube from loosely detachment in operation.

3. The adjustment device 3 and the adjustment rod 60 are both concealed in the minor tube 80 and the major tube 70 in a compact manner so as to make the structure appealing to eyes.

Claims

CLAIMS 1. A retaining and releasing mechanism adapted for use in a telescopic tube wherein an adjustment device comprises: a pair of case halves forming a housing case; an elongated urging plate has one end extending out of said housing case and engaged with a control means located externally of a telescopic minor tube; a bias spring is confined at one end in said housing case and is engaged with said elongated urging plate at the other end so as to make said urging plate retractably move back and forth with respect to said housing case; an adjustment rod is led through said housing case with said adjustment device either selectively retained thereto or slidable thereon; a major tube is used for housing said housing case and said minor tube that are telescopically extendable and retractable therein as a whole; said adjustment rod has one end engaged with one end of said major tube; a main retaining ring unit and a secondary retaining ring unit are housed in said housing case and obliquely mounted onto said adjustment rod with a compression spring placed therebetween; both said main retaining ring unit and said secondary retaining ring unit are provided with an activation means selectively engaged with said elongated urging plate so as to controllably bring said obliquely positioned main and secondary retaining ring units and said restraint rings either normal to or oblique with respect to said adjustment

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rod; a plurality of restraint rings are obliquely mounted onto said adjustment rod and located half thereof at each end of said compression spring and are in abutment against said main retaining unit and said secondary retaining unit respectively; said main retaining ring unit, said secondary retaining ring unit and said multiple restraint rings are drivable by said urging plate to move in a position normal to said adjustment rod when said control means is activated to release said adjustment rod from frictional restraint of said main and secondary retaining ring units and said restraint rings, permitting said adjustment device and said minor tube to be movable on said adjustment rod for adjustment of the length of said telescopic tube.
2. A retaining and releasing mechanism as claimed in claim 1 wherein said control means is a push button disposed at an end of said minor tube.
3. A retaining and releasing mechanism as claimed in claim 1 or claim 2 wherein said adjustment rod is integrally fixed to a bottom end of said major tube.
4. A retaining and releasing mechanism as claimed in any one of the preceding claims wherein said housing case is made in any shape in conformance to an article to which said telescopic tube is applied.
5. A retaining and releasing mechanism as claimed in any one of the preceding claims wherein said activation means of said main and secondary retaining units is a pressing stick integrally fixed

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to a summit point thereof respectively; said activation means can be exposed externally of said housing case and be actuated by a pressing means engaged therewith directly in operation.
6. The retaining and releasing mechanism as claimed in any one of the preceding claims wherein said restraint rings are added in number to increase frictional retaining force of said adjustment device exerted on said adjustment rod.
7. A retaining and releasing mechanism as claimed in any one of the preceding claims wherein said housing case is provided with a limiting cavity for receiving said main and secondary retaining units and said restraint rings and said compression spring therein; said limiting cavity has two opposite oblique walls for supporting said main and secondary retaining ring units and said restraint rings in a slant manner.
8. A retaining and releasing mechanism substantially as hereinbefore described with reference to or as shown in the accompanying drawings.