Belt closure and chin strap of a protective helmet equipped therewith

Abstract

A belt fastener for detachably connecting two belt ends has a housing and a plug, which can be clipped into the housing. The belt fastener can be a safety fastener opening if a predetermined tensile load acts on the belt ends. A separate finger flap is hinged to a front end of the plug for clipping it into the housing. The finger flap preloaded outwards in direction away from the plug by a separate spring. The finger flap can be brought in abutment with a stop surface of the housing by means of a stop surface opposite of the attachment point. Both stop surfaces are tilted forward by an angle of inclination () of >0, particularly of 20. In addition, two stop surfaces can be convexly or concavely curved.

Claims

1. A belt fastener for detachably connecting two belt ends, comprising: a housing connectable or connected to one of the belt ends, and a plug which can be clipped into the housing and is connectable or connected to the other belt end, wherein the fastener is formed as a safety fastener which opens if a specific tensile load acts on the belt ends or on the housing and the plug, and wherein the plug to be clipped into the housing comprises a separate finger flap which is located on one of its wide sides and hinged to a bolt at a front end of the plug.

2. The belt fastener according to claim 1, wherein the finger flap is preloaded by a separate spring in the direction of a position in which the finger flap protrudes towards the outside beyond the plug.

3. The belt fastener according to claim 2, wherein the position in which the finger flap protrudes towards the outside beyond the plug is defined by a protrusion on the finger flap which can be brought in abutment on a protrusion on a body of the plug.

4. The belt fastener according to claim 1, wherein a spring is a one or more leg spring surrounding the bolt and supported on the finger flap and on the body of the plug at its free ends.

5. The belt fastener according to claim 1, wherein the finger flap comprises a stop surface at its end opposing its attachment point, which stop surface abuts to a stop surface in a finger opening formed in of a wide side of the housing when the plug is inserted in the housing.

6. The belt fastener according to claim 5, wherein the two stop surfaces are tilted forward by an angle () not equal to 0 with respect to a perpendicular to the insertion direction of the plug.

7. The belt fastener according to claim 6, wherein the angle of inclination () is 20.

8. The belt fastener according to claim 5, wherein the two stop surfaces are convex or concave and curved so that the stop surface of the finger flap has a radius of curvature (R.sub.2) which is smaller than the radius of curvature (R.sub.1) of the stop surface of the finger opening.

Description

(1) In the following, embodiments of the invention will be described in more detail with reference to the drawings in which:

(2) FIG. 1 shows a longitudinal sectional view of a preferred embodiment of a belt fastener according to the invention connecting two belt straps with each other and illustrated in a closed state,

(3) FIG. 2 shows the belt fastener according to FIG. 1 in a slightly perspective side view,

(4) FIG. 3 shows the belt fastener according to FIG. 2 in an approximately identical perspective view, however, in addition in a longitudinal section,

(5) FIG. 4 shows the belt fastener according to FIG. 1 approximately in a top view,

(6) FIG. 5 shows a top view of the plug of the belt fastener according to FIG. 1 as a detail,

(7) FIG. 6 shows a perspective view of the housing of the belt fastener according to FIG. 1 as a detail, and

(8) FIG. 7 shows a perspective view of the plug of the belt fastener according to FIG. 1 as a detail.

(9) FIGS. 1 to 7 show a belt fastener altogether designated by 20 and comprising two ends 10a, 10b of a strap or belt 10 attached to it. The strap 10 may be formed as a part of a support means of a protective helmet none of which is shown. The belt fastener 20 comprises a housing 30 and a plug 40 insertable into the housing 30. In FIG. 1 which shows a longitudinal sectional view of the strap 10 including the belt fastener 20 the plug 40 is inserted into the housing 30 and engaged or latched there in the manner described in more detail below. FIG. 2 shows the strap 10 and the belt fastener 20 according to FIG. 1 in a slightly perspective side view. FIG. 4 shows the strap 10 and the belt fastener 20 according to FIG. 1 approximately in a top view. On the other hand the plug 40 of the belt fastener 20 according to FIG. 1 shown in a top view in FIG. 5 and the housing 30 of the belt fastener 20 according to FIG. 1 shown in a perspective view in FIG. 6 are respectively shown in detail. FIG. 3 shows a view as shown in FIG. 2, however, in addition also in a longitudinal section. FIG. 7 shows a perspective view of the plug 40 according to FIG. 1 as a detail.

(10) According to the illustration in FIGS. 1 and 5 the plug 40 comprises a finger flap 44 disposed on one of its wide sides (in FIG. 5, it is the wide side facing the observer). The finger flap 44 is hinged to a bolt 48 at a front end 42 of the plug 40 as can be seen in FIGS. 1, 3 and 7. The bolt 48 is non-rotatably supported in two bearing blocks integrally formed with a body 49 of the plug 40 which, however, are not illustrated in the drawings. To this end the bolt 48 may simply have a force fit in the bearing blocks. The finger flap 44 is a separate component, i.e. a component separate from the plug 40 which is separately produced and then pivotably connected to the body 49 of the plug 40 with the aid of the bolt 48. An insertion direction, i.e. the direction in which the plug 40 is inserted into the housing 30, is indicated by an arrow 46 in FIG. 1. In FIG. 1 the plug 40 is inserted into the housing 30 from the right to the left so that the front end 42 of the plug 40 is the end shown on the left side in FIG. 1. The interior of the housing 30 matches the outer shape of the plug 40 so that the inserted plug 40 has no noteworthy clearance in the housing.

(11) Around the bolt 48 a spring 50 is mounted which is a leg spring formed so that das the free ends of its legs 51, 52 strive to move away from each other in the embodiment of the belt fastener 20 described here and shown in the drawings. The spring 50 surrounds the bolt 48 and is supported on the finger flap 44 and on the body 49 of the plug 40 on protrusions 41 a and 41 b at the free ends of its legs 51, 52 as can be best seen in FIG. 1. In this way the finger flap 44 is preloaded by the spring 50 in direction of a position in which the finger flap 44 protrudes towards the outside beyond the plug 40, to put it more precisely, beyond the body 49 of the plug 40. This position the finger flap 44 is shown in FIGS. 1, 3 and 7. In the slightly perspective longitudinal sectional view shown in FIG. 3 it can be seen that the spring 50 is a two-legged spring. A two-legged spring develops more force than a one-legged spring. The position in which the finger flap 44 protrudes towards the outside beyond the plug 40 or its body 49 is, according to the illustration in FIG. 1, defined by a protrusion 45 on the finger flap 44 abutting on a protrusion 43 on the body 49 of the plug 40. Owing to the mutual contact of the protrusions 43 and 45 the pivoting of the leg spring 50 about the bolt 48 is limited counterclockwise. By selecting the material of the spring 50 and the number of the legs the force applied to the protrusion 43 by the spring of the finger flap 44 can be selected.

(12) Any spring providing the tension required for the opening force may be selected as the spring 50. Instead of a leg spring it could therefore be a compression spring, a laminated spring, resilient plastic elements, laminated carbon springs, coil springs made of carbon or any other type of spring. In the embodiment described here the two-legged spring is made of high alloy steel and therefore its characteristics will not substantially change in a temperature range of 30 to +40 C. Both the finger flap 44 and the plug 40 were manufactured as separate die cast components. Both were then assembled with the aid of the bolt 48 while incorporating the spring 50. This design of the spring 50 provides for more constant characteristics across the abovementioned temperature range than a plastic spring integrally formed with a plastic plug and only connected to it by a plastic bridge as in the state of the art described in the introduction. Even though, instead of a leg spring, a compression spring could be disposed transverse to the insertion direction 46 between the body 49 of the plug 40 and the finger flap 44, the spring 50 used in the embodiment shown acts on the finger flap via a long lever arm which provides for an increase of force.

(13) The finger flap 44 has a stop surface 47 at its end opposing its attachment point on the bolt 48 which abuts on a stop surface 67 in a finger opening 60 formed in a wide side of the housing 30 when the plug 40 is inserted in the housing 30 as shown in FIG. 1. The finger opening 60 can be best seen in FIG. 6 in which the housing 30 is shown in detail in a perspective view. The two stop surfaces 47, 67 are formed so that they are obliquely tilted forward relative to the insertion direction 46 of the plug 40. In the shown embodiment the two stop surfaces 47, 67 together with a perpendicular 70 located in the longitudinal sectional plane of the fastener 20 on an arrow line located in the same plane which symbolizes the insertion direction 46 of the plug 40 respectively form an angle of inclination a of approximately 20. The angle of inclination a is selected depending on the desired force. The larger the angle a is made the smaller the pulling force will become which has to be exerted on the belt ends 10a, 10b to automatically open the belt fastener 20.

(14) If, on the other hand, the belt fastener 20 is to be opened manually a finger is pressed onto the finger flap 44 through the finger opening 60, and the former is thereby pressed into the plug 40 from the position shown in FIG. 1 against the force of the spring 50, and the belt fastener is opened manually in this way.

(15) In the cross section, i.e. substantially transverse to the insertion direction 46, the housing 30 and the plug 40 substantially have the form of a flat rectangle, respectively, and are formed so that the finger opening 60 and the finger flap 44 respectively extend in one of the side walls of their allocated rectangles. In other words, the finger flap 44 is disposed in one of the wide sides of the body 49 of the plug 40, and the finger opening 60 is disposed in one of the wide sides of the housing 30 as can be readily seen in FIGS. 5 and 6.

(16) According to FIG. 1, the two stop surfaces 47, 67 are convexly or concavely curved in the top view, i.e. as regarded from the top. The stop surface 47 of the finger flap 44 has a radius of curvature R.sub.2 which is smaller than a radius of curvature R.sub.1 of the stop surface 67 of the finger opening 60. The radiuses of curvature R.sub.1 and R.sub.2 are indicated in FIG. 6 or 7. Owing to this design the stop surfaces 47, 67 are not in a mutual surface contact but in a mutual line contact when they abut as shown in FIGS. 1 and 2 to 4. If the tensile load is applied to the belt ends 10a, 10b in a line with the insertion direction 46 the contact line is located in a transverse central plane of the finger flap 44 and of the housings 30 in which also the insertion direction 46 and the perpendicular 70 are located. If the tensile load is applied obliquely with regard to the insertion direction 46 the contact line will move upwards or downwards in FIG. 4 depending on the pull direction.

(17) Since the belt fastener 20 is designed as a safety fastener which is to open at a specific tensile load acting on the strap 10 the angle a is selected so that, at a specific tensile load acting on the strap 10, the force by which the stop surfaces 47, 67 are pressed against each other will ultimately become so large that the finger flap 44 is moved into the plug 40 owing to the force component which will then act on the finger flap 44 orthogonally with respect to the insertion direction 46 and strive to move the finger flap 44 into the plug 40. As soon as the stop surfaces 47 and 67 have gotten clear of each other, i.e. the finger flap 44 has sufficiently moved into the plug 40 at its, according to FIG. 1, right end in the finger opening 60, the plug 40 is pulled out of the housing 30 owing to the tensile load still acting on the strap 10. The belt fastener 20 thus automatically opens at a specific tensile load acting on the strap 10 which is why it is referred to as a safety fastener here.

(18) The chin strap of a protective helmet (both not shown) may be equipped with the belt fastener according to the invention. In this case the attachment points of the chin strap on the inside of the helmet or on the support means of the same do not have to be modified so that the helmet is released at a specific tensile load acting on the chin strap since this release is effected only by opening the belt fastener according to the invention.