RISTOLA, Jari (Panssariura 7, Ylämylly, FI-80400, FI)
| Claims
1. A sleeve joint between an outer tube (30) and an inner tube (31) in a telescopically adjustable-length shaft, said sleeve joint comprising a muff-like body member (1) mounted to an end of the outer tube (30), in the proximity of the rim of said body member's (1) opening being disposed mutually aligned fastening brackets (12) which include helical wedge surfaces (13), a fastening lever (20) linked with the fastening brackets (12), which is rotatable relative to the helical wedge surfaces (13) around a substantially transversal rotation axis (x) and which has its end proximal to the rotation axis (x) formed with legs (22) whose ends are provided with clamping wedge surfaces (23) matched with the wedge surfaces (13) of the fastening brackets (12), as well as a screw-threaded tension bar (26), which constitutes a rotation axle for the clamping wedge surfaces (23) and which, in response to rotating the clamping wedge surfaces (23) by means of the clamping lever (20), takes up clamping forces substantially codirectional with the rotation axis (x) and applied to the clamping wedge surfaces (23), characterized in that the body member (1), in the proximity of the opening's rim, is formed with pliable protrusions (3) as an axial extension of the body member (1), and that the fastening brackets (12) are disposed on a clamping sleeve (10) capable of being removably fitted around the pliable protrusions (3), whereby the protrusions (3), in response to pivoting the clamping lever (20), compress around the inner tube (31).
2. A sleeve joint as set forth in claim 1, characterized in that the body member (1) features a bulge (5) which functions as an end extension of the fastening lever (20) in an engaged position of the fastening lever (20).
3. A sleeve joint as set forth in claim 1 or 2, characterized in that the fastening lever (20) is provided with lateral gripping formations (25).
4. A sleeve joint as set forth in any of the preceding claims 1-3, characterized in that between the clamping sleeve (10) and the body member (1) is a rotation- impeding locking profile (15), which only permits attachment of the clamping sleeve (10) to the body member (1) at a single relative angle of rotation.
5. A sleeve joint as set forth in any of the preceding claims 1-4, characterized in that the number of protrusions (3) is at least two.
6. A sleeve joint as set forth in any of the preceding claims 1-5, characterized in that the material of the pliable protrusions (3) is more flexible/softer than that of the clamping sleeve (10).
7. A sleeve joint as set forth in any of the preceding claims 1-6, characterized in that the body member (1) consists of a basic element (2) and the pliable protrusions (3) made in a single piece. |
Sleeve joint between the outer tube and the inner tube of a telescopically lengthwise adjustable shaft
The present invention relates to a sleeve joint between an outer tube and an inner tube in a telescopically adjustable-length shaft, said sleeve joint comprising a muff- like body member mounted to an end of the outer tube, in the proximity of the rim of said body member's opening being disposed mutually aligned fastening brackets which include helical wedge surfaces, a fastening lever linked with the fastening brackets, which is rotatable relative to the helical wedge surfaces around a substantially transversal rotation axis and which has its end proximal to the rotation axis formed with legs whose ends are provided with clamping wedge surfaces matched with the wedge surfaces of the fastening brackets, as well as a screw- threaded tension bar, which constitutes a rotation axle for the clamping wedge surfaces and which, in response to rotating the clamping wedge surfaces by means of the clamping lever, takes up clamping forces substantially codirectional with the rotation axis and applied to the clamping wedge surfaces.
This type of sleeve joint is known from the Applicant's own Patent publication FI 113252. It discloses a muff-like body member, which also includes mutually aligned fastening brackets. The body member, between the fastening brackets, is formed with a single longitudinal split, the compression of its sides towards each other by means of a profiled locking mechanism (including, among others, a tension bar and a clamping lever) enabling the inner tube to be locked in a fixed position relative to the outer tube. This results in a comparatively high-quality and reliable locking. A drawback with this type of joint is, however, that, in order to provide a sufficient grip between the tubes, the compression of the split sides towards each other requires the use of a considerable force. This also exposes the profiled locking mechanism to rapid wear. The compensation of a considerable force requires a relatively long locking lever, which gives the joint area a clumsy appearance and a propensity to make, for example, inadvertent contact with articles in its vicinity.
An object of the present invention is to eliminate or at least substantially alleviate the above drawbacks.
The foregoing object of the present invention is accomplished, according to the present invention, in such a way that the body member, in the proximity of the opening's rim, is formed with pliable protrusions as an axial extension of the body member, and that the fastening brackets are disposed on a clamping sleeve capable of being removably fitted around the pliable protrusions, whereby the protrusions, in response to pivoting the clamping lever, compress around the inner tube.
This sleeve joint according to the invention is capable of fulfilling the above object. In other words, a separate clamping sleeve makes it possible to provide pliable protrusions. Preferably, the pliable protrusions are made of a material which is more flexible and/or softer than that of the clamping sleeve. The pliable protrusions are located equidistantly as an extension of the muff-like body member's circumferential wall. Thus, a compressive force produced by the clamping sleeve becomes evenly distributed across the circumferential wall and further on the inner tube. Hence, for a joint between the outer and inner tubes, with a strength equivalent to what is achieved in the prior art, lesser forces will be required between the wedge surfaces of the fastening brackets and the clamping wedge surfaces. As a result of this, the pivoting force applied to the fastening lever for the attachment of a clamping sleeve will also be lesser than what is used in the prior art. Another advantage is hence a lesser wear of the joint mechanism. Considering the same from another standpoint, with respect to the prior art, this enables a clearly stronger joint between tubes with the same clamping force.
A telescopic shaft provided with a sleeve joint of the invention is useful for many applications, such as for implement handles for cleaning, building maintenance or gardening, as well as for masts, posts, legs of furniture, tripods and other such applications.
Preferred embodiments of the present invention are presented in the dependent claims.
The invention will now be described more closely with reference to the accompanying drawings, in which:
Fig. 1 shows a sleeve joint of the invention in a fragmentary view, and
Fig. 2 shows a sleeve joint of the invention.
In reference to figs. 1 and 2, there are shown a sleeve joint according to the present invention and components included therein. The sleeve joint comprises an outer tube indicated by reference numeral 30 and an inner tube indicated by reference numeral 31. The tubes are circular in this embodiment. The inner tube 31 has an outer diameter which is smaller than the outer tube's inner diameter. Between the tubes 30 and 31 is provided a sliding fit to enable relative sliding therebetween. By virtue of the sliding fit, the shaft retains its rigidity at the joint area despite being subjected to forces lateral with respect to the shaft, thus preventing for example the occurrence of buckling.
Partially around one end of the outer tube 1 is disposed a sleeve joint member, including a body member 1, clamping sleeve 10, a fastening lever 20, and a tension bar 26. The muff-like body member 1 is permanently attached to the outer tube 30. The outer tube 30 is set inside the sleeve's body member 1 in its axial direction, preferably over a distance which is about half of the body member's 1 length. Thus, one open end of the body member 1 serves as an axial extension of the outer tube 30, whereby the inner tube 31 can be pushed through the body member's 1 open end into the sleeve joint member and further into the outer tube 30.
The body member 1 has its open end formed, as an axial extension thereof, with elongated protrusions 3, which are separated from each other by splits 3a. Material for the protrusions is selected to allow for the bending thereof radially relative to the body member 1 whenever a radial or at least a substantially radial force is applied thereto. The material can be for example a type of plastic apt for injection moulding. The pliable protrusions 3 can be spaced from the body member by way of a circumferential slot 3b for more flexibility. The slot 3b can be circumferentially longer than what is depicted in fig. 1. The number of protrusions is preferably 2-10, for example four, as can be seen in the figures. The pliable protrusions 3 are coupled with a basic element 2 of the body member 1 and can be made in a single piece with the basic element 2.
The protrusions 3 have the outer surface thereof designed for taking up a clamping sleeve 10. The clamping sleeve is preferably made from a metal, such as aluminium, which due to its lightness is very useful as a sleeve material. The clamping sleeve 10 is introduced in axial direction around the protrusions 3. The clamping sleeve 10 has its outer surface formed with two separate parallel fastening brackets 12 whose outwardly facing surfaces are provided with helical wedge surfaces 13. The clamping wedge surfaces are otherwise identically designed except for being mirror images with respect to a longitudinal axis L of the body member 1. An example of the design of clamping wedge surfaces is presented in the Applicant's patent publication FI 113252 in the context of complementary wedge surfaces formed on a jointing sleeve. A more detailed description of the construction is not necessary in this specification. The fastening sleeve 10, between the fastening brackets 12, is formed with a longitudinal split 14, extending lengthwise across the entire sleeve 10. The split has a width which is preferably substantially equal to a distance of the fastening brackets from each other. Naturally, the split may have a width other than that.
The sleeve joint includes also a separate fastening lever 20, the first end of which is formed with two legs 22. The legs 22 have the ends thereof provided with clamping rings whose end faces constitute clamping wedge surfaces 23 oppositely aligned with each other. In terms of the designs thereof, the clamping wedge surfaces 23 are substantially similar to the wedge surfaces 13. The fastening lever 20 is preferably manufactured in a wear-resistant material, such as a metal, for example aluminium.
A process of engaging the fastening lever 20 with the clamping sleeve 10 proceeds by pushing it into contact with the sleeve's 10 fastening brackets 12, such that the lever's 20 clamping wedge surfaces 23 rotate around an axis x against the wedge surfaces 13. Fixing the fastening lever 20 in position can be preferably effected in such a way that the legs 22 are pulled away from each other and the fastening brackets are pushed against each other. Thereby, the latter can be easily placed in a correct position relative to the axis x. When the pulling and pushing actions are released, the wedge surfaces and the clamping wedge surfaces compress against each other.
The attachment of a tension bar 26 can be effected in a way applied from FI 113252. In the middle of a first clamping wedge surface 23 is formed an aperture 27 extending through the clamping ring and in the middle of a second clamping wedge surface 23 is formed an aperture (not shown) extending partly through the clamping ring, the latter opening having its inner surface provided with a threading. Alternatively, a threading designed on the clamping ring can be replaced with a nut embedded in the clamping ring.
With the fastening lever 20 properly mounted in position on the clamping sleeve 10, the fastening lever's 20 apertures 27 (as well as a screw-threaded hole, not shown) as well as the fastening brackets' openings 15 will be in alignment with each other. Hence, a screw-threaded tension bar 26 can be fitted in position by passing the tension bar 26 through the aperture 27 and through the fastening brackets' openings 15 and by tightening it securely onto a second threading of the clamping ring. The tension bar's 26 longitudinal axis (rotation axis of the clamping lever) extends in a direction which is transversal to the body member's 1 longitudinal axis. What transpires between the wedge surfaces 13 and the clamping wedge surfaces 23 as the fastening lever 20 is pivoted has been described more thoroughly in the Applicant's patent publication FI 133252.
A rotatory motion for the fastening lever 20 and the clamping wedge surfaces 23 (between locked and released positions) is brought about by means of a pivotable lever segment 21 or a lever arm present as an extension of the fastening lever's 20 legs 22. Once the clamping sleeve 10 has been set around the protrusions 3, the fastening lever 20 can be pivoted to an engagement position (see fig. 2). Thereby, by way of the tension bar 26, the clamping sleeve's 10 fastening brackets 12 are subjected to a compressive force (force parallel to the axis x), the result being that the width of the split and thereby the diameter of the clamping sleeve 10 become smaller. Thus, the radially flexible protrusions 3 compress in a radial direction towards the body member's 1 centre axis while the clamping sleeve's 10 inner surface compresses against the protrusions' 3 external surface. Thereby, in turn, the protrusions' 3 internal surfaces compress against the external surface of a smaller tube 31 extended through the clamping sleeve 10 and the muff-like body member 1 part-way inside a larger tube 30.
Referring particularly to fig. 2, it can be seen that the lever segment's 21 end of the fastening lever 20 terminates in the body member's 1 longitudinal direction at a position short of the extremity of the body member 1. Therefore, this particular end region of the body member 1 is preferably provided with a bulge 5, which forms an extension to the fastening lever's 20 end in an engaged position of the fastening lever 20. The purpose of this is to block the penetration of various particles by way of the fastening lever's 20 end in between the fastening lever 20 and the body member 1 and to prevent even an inadvertent disengagement of the joint.
For disengaging the joint or for facilitating its disengagement, the fastening lever 20 has its sides provided with gripping formations 25. The formation can be for example a bulge along the side, as shown in the figures. Furthermore, the body member's basic element 2 is preferably formed with a recess 6 which is coincidental with the gripping formation 25 in the body member's longitudinal direction. A convenient gripping point for the user's fingers in view of opening the joint is provided by the bulge 25 alone, but even more so when accompanied by the recess 6.
According to one preferred embodiment of the invention, between the clamping sleeve 10 and the body member 1 is provided a rotation-impeding locking profile, which only permits attachment of the clamping sleeve 10 to the body member 1 at a single relative angle of rotation. Therefore, the clamping sleeve 10 is formed with a tongue 15 circumferential in the sleeve's 10 longitudinal direction. The tongue 15 can be introduced into a complementary formation, preferably a groove (not shown), provided in the body member. Thereby, rotation of the sleeve 10 around its longitudinal axis will be denied.
The present invention is not limited to the described embodiments. The invention finds a wide range of applications within a scope of protection as defined in the claims.