GB2079841A

GB2079841A - A hose clamp

Info

Publication number: GB2079841A
Application number: GB8120974A
Authority: GB
Original assignee: Nissan Motor Co Ltd; Kato Hatsujo Inc
Current assignee: Piolax Inc; Nissan Motor Co Ltd
Priority date: 1980-07-08
Filing date: 1981-07-07
Publication date: 1982-01-27
Also published as: JPS5719285U; FR2486622B1; GB2079841B; JPS5848464Y2; DE3126617A1; FR2486622A1

Abstract

A hose clamp 11 formed by bending from flat plate material comprises an annular clamping portion (12) having at one end a releasing arm (13) which fits between a pair of further releasing arms (13') at the other end of the portion (12). The width of the clamping portion (12) varies along its length in a manner selected to minimise variations in stress across its thickness when the gripping arms (13, 13') are operated to open the clamp, so as to reduce the likelihood of the clamping portion breaking upon re-use of the clamp. Particular formulae are disclosed for calculating the width of the clamping portion. <IMAGE>

Description

SPECIFICATION Hose clamp This invention relates to a clamp and, more particularly, to an improvement in a hose clamp formed of an elastic flat plate material.

A conventional hose clamp, generally designated by reference numeral 1 of this type is formed, as shown, for example, in Figs. 1A and 1 B, of an annular clamping portion 2 which is formed by bending an elastic flat plate material 4 having a constant width B and a rectangular cross section, of one gripping end portion 3, and of a pair of the other gripping end portions 3' and 3' for gripping to expand the diameter of the clamping portion 2.

When the hose clamp 1 thus formed is used, a hose is exactly clamped by means of the elastic force of the hose clamp 1 itself in the steps of approaching the one gripping end portion 3 and the other gripping end portions 3' and 3' in a direction as designated by confronting arrows in Fig. 1 B therebetween against the elastic force of the hose clamp 1 itself to thereby expand the diameter of the clamping portion 2, inserting a hose (not shown) into the central space of the clamping portion 2 thus expanded and then releasing the approached gripping end portions 3 and 3', 3'.It is however matters of common knowledge, that, when the one and the other gripping end portions 3 and 3', 3' are thus approached each other to expand the diameter of the clamping portion 2 as described above, different stresses are produced at different positions such as, for example, at the respective positions designated by reference characters a, b, c and d of the clamping portion 2 by the clamping force of the clamping portion as acted at the time of approaching therebetween. That is, larger stresses are produced sequentially in the order of the positions a, b, c and d of the clamping portion 2.It is accordingly a large disadvantage of the conventional hose clamp 1 that, as the clamping force is increased, the stress at the position d of the clamping portion 2 is particularly at maximum and the clamping portion 2 is resultantly plastically deformed frequently to thus cause the position d thereof to consequently break.

Accordingly, there have been developed and proposed one hose clamp 1 which, as shown in Figs. 3A and 3B, employed an elastic flat plate 5 in which the width B of the clamping portion 2 is rectilinearly varied, another hose clamp 1 which, as shown in Fig.

4, adopted a reinforcing rib 6 formed at generally central portion on the outer peripheral surface of the position where the higher stress is produced of the clamping portion 2 thereof, and the other hose clamp 1 which, as shown in Fig. 5, incorporated a generally triangular slit 7 perforated in the vicinity of the one and the other gripping end portions 3 and 3', 3' where are of lower deformation resistances of the clamping portion 2. However, all these hose clamps thus proposed to eliminate the disadvantages of the conventional one were not constructed in configuration by considering accurately the bending moment and the axial force produced at the respective positions on the clamping portion 2 owing to the clamping force of the gripping end portions thereof. Consequently, the stresses were largely varied at the respective positions on the clamping portions of the hose clamps.This has an apprehension of plastic deformation caused over the allowable stress on the clamping portion at the time of expanding the diameter of the clamping portion of the conventional hose clamps. In addition, the conventional hose clamps have a difficulty of retaining the roundness of the clamping portion at the time of clamping a hose.

Accordingly, a primary object of this invention is to provide a hose clamp which eliminates the aforementioned disadvantages of the conventional hose clamp.

Another object of this invention is to provide a hose clamp which can exactly prevent the plastic deformation produced in the conventional hose clamp at the time of expanding the diameter of the clamping portion thereof.

Yet another object of this invention is to provide a hose clamp which can be extremely easily formed in preferable shape.

A further object of this invention is to provide a hose clamp which can equalize the stresses produced at different positions on the clamping portion thereof.

Still another object of this invention is to provide a hose clamp which can retain the roundness of the clamping portion even at the time of clamping a hose.

According to one aspect of this invention, there is provided an improved hose clamp which incorporates a swelled portion increased in width at the portion of a clamping portion so formed as to produce a constant stress caused by the bending moment and the axial force at the position d where higher bending moment and axial force than predetermined values, that is, the maximum stress is applied of the respective positions on the clamping portion thereof.

The above and other related objects and features of the invention will be apparent from a reading of the following description of the disclosure found in the accompanying drawings and the novelty thereof pointed out in the appended claims.

Figures 1A and 1B are plan and perspective views of the developed and the assembled state of the conventional hose clamp; Figure 2 is an explanatory view of the respective positions a through d of the clamping portion of the conventional hose clamp; Figures 3A and 3B are views similar to Figs. 1A and 1 B but showing another example of the conventional hose clamp; Figures 4 and 5 are perspective views of the other conventional hose clamps; Figure 6A is a plan view of the developed state of one preferred embodiment of the hose clamp constructed according to this invention; Figure 6B is a perspective view of the hose clamp of this invention; Figures 7A and 7B are diagrams for the explanatory purpose of calculation formulae for obtaining the stresses at different positions on the clamping portion of the hose clamp; and Figure 8 is a diagram showing the stresses at various angles on the clamping portion from the position d of the hose clamp.

Referring now to the drawings, particularly to Figs. 6A and 6B showing one preferred embodiment of the hose clamp constructed according to this invention, a hose clamp, generally designated by reference numeral 11, consists of an annular clamping portion 12 which is formed, as shown in Fig. 1 B by continuously bending an elastic flat plate material 14 shown in shape in Fig. 1A by a press or a forming machine in configuration corresponding to the circle having an outer diameter of a hose to be inserted into the central space thereof and to be clamped thereby, one gripping end portion 13 and a pair of the other gripping end portions 13' and 13 for gripping to expand the diameter of the clamping portion 12. The width B of the clamping portion 12 forming the hose clamp 11 of this invention is advantageously obtained as below.

Stresses a1 and a,, which represent the stresses produced on the outer and the inner peripheral surfaces of the hose clamp 11 of this invention, are obtained by calculating them with the hose clamp 11 regarded as a "bending beam". Accordingly, the stresses a, and (F2 can be obtained by the following formulae:

where, in Fig. 7A, A: Cross sectional area = width B x thick ness t N: Axiai force acting on the calculated cross section M : Bending moment acting on the calcu lated cross section Po : Radius of curvature of the neutral axis of bending beam pro = r e,:Distance from the neutral axis to the outer peripheral surface = t 2 e2 : Distance from the neutral axis to the inner peripheral surface = t 2 Constant The bending moment M and the axial force N acting on the respective positions of the clamping portion of the hose clamp are obtained by the following formulae with reference to Fig. 7B.

M -W.r(1 + cos @) (3) N = W.cos 8 (4) where W represents the clamping force of the clamping portion when the gripping end portions 13 and 13', 13' are approached in assumption. The clamping portion 12 is so formed, as shown in Fig. 8, in equi-stress state in swelled shape having a width B obtained by the following formula at the position where the stresses a, and a2 produced on the outer and the inner peripheral surfaces of the hose clamp 11 exceed a predetermined reference value such as, for example, allowable stress values a1' and s2'. More particularly, the values of the M and N of the formulae (3) and (4) are substituted for the formulae (1) and (2), and the width B of the clamping portion 12 of the hose clamp 11 is obtained with respect to the reference values v11 and a2' as below.

Thus, the width of the clamping portion 12 of the hose clamp 11 in configuration at the portion where the stress value may approach its elastic limit when the width B is formed constantly is determined by calculating the formula (5) or (6) of the widths at the different positions on the clamping portion 12 as swelled portion in width B in Fig. 6A.

It is noted that the width B determined by calculating the formula (5) or (6) is not applied to all the periphery of the clamping portion 12 of the hose clamp 11, because if all the periphery of the clamping portion is formed in equi-stress state, the width B of the clamping portion 11 in the vicinity of the gripping end portions 1 3 and 1 3', 1 3' having low bending stress and axial force may become extremely narrow in no practical way.

It should be understood from the foregoing description that since the hose clamp of this invention is so constructed at the clamping portion that the width and shape of the clamping portion is determined at predetermined position where higher bending moment and axial force than predetermined values are acted by the clamping force of the gripping end portions in such a manner that the stress values calculated on the basis of the theory of a bending beam become equal therealong and accordingly that the swelling portion is formed in width thereof, it can exactly prevent the plastic deformation produced in the conventional hose clamp at the time of expanding the diameter of the clamping portion thereof, can be extremely easily formed in preferable shape, can equalize the stresses produced at different positions on the clamping portion thereof, and can retain the roundness of the clamping portion even at the time of clamping a hose.

Claims

1. A hose clamping comprising: an annular clamping portion formed by bending an elastic flat plate material; one gripping end portion; and a pair of other gripping end portions for gripping to expand the diameter of said clamping with both the gripping ends wherein a predetermined portion of said clamping portion is so formed in a swelled shape that the width of the position where the maximum stress is applied of said clamping portion is at a maximum in such a manner that the stress values of the respective positions of a predetermined portion of said clamping portion become equal to each other.

2. The clamp according to claim 1, wherein the width B of said clamping portion thereof is obtained by calculating the following formula with respect to reference stress values:

where a,' and (J2' represent reference stresses like allowable stresses M : bending moment acting on the calcu lated cross section N : axial force acting on the calculated cross section r : radius of curvature of the neutral axis of a bending beam under the condition that said hose clamp is regarded as a bend ing beam t : thickness of said clamping portion K: constant.