Abstract:
A toe unit for a safety ski binding for disposal on a horizontal surface of a ski includes a base adapted to be mounted on the ski, a bolt having a lower end and an upper end, and a mounting portion for mounting the lower end of the bolt to the base. The mounting portion permits axial movement of the bolt between a first position and a second position, and secures the bolt substantially perpendicular to the horizontal surface of the ski when the bolt is in the first position. The mounting portion also permits pivotal movement of the bolt about a location on the base when the bolt is in the second position. The toe unit also includes a sole contact portion attached to the bolt for retaining a sole of a boot and for moving the bolt axially from the first position to the second position in response to a predetermined force exerted by the boot in a direction away from the base.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a toe unit for safety ski bindings. More particularly, the invention relates to easy withdrawal of the boot in the event of a fall. 
     This type of toe unit kind is described in several embodiments in U.S. Pat. No. 4,268,064 to Svoboda. With the constructions shown in FIGS. 1-6, the centering of the bolt, in the running position, is effected by means of an elastic compound annularly surrounding the bolt and held in position by a component rigidly fixed to the ski. For example, although the ring shown in FIG. 6 can perform a certain elastic holding function on the bolt, and thereby on the sole retainer, it is nevertheless impossible to lock the bolt, and consequently the sole retainer, in this way through its shape. Hence, this design has the drawback that it is possible for the bolt, and thus for the sole retainer, to swivel even in the course of skiing, that is to say, at a time when the bolt carrying the sole retainer is to be held immovably in position. 
     By contrast, with the constructions shown in FIGS. 7-15, the bolt is locked by means of cams located on projections of the two bell-crank levers. In the event of a backward-twisting fall, release of the bolt is not possible until one of the bell-crank levers has already been swung to a specific angle by the ski boot of the skier, but this will cause a delay in the reduction of the friction between the sole retainer, and the ski boot. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to overcome the drawbacks of prior constructions and to provide a toe unit which, at the onset of a backward-twisting fall by the skier, lifts the sole retainer, which, in the running position, is locked and thereby reduces without delay the friction between the sole retainer and the sole of the boot. 
     To achieve this object, there is provided a safety ski binding comprising two bell-crank levers which are capable of laterally embracing a boot sole and are each swingable on an axis perpendicular tot eh top of a ski against a force applied by a release spring. A sole retainer is provided and is adjustable in a direction perpendicular to the top of the ski. A bolt is mounted at its lower end in a slot in a base. The base can be, for example, a base plate or a carrying member or a control block mounted in a carrier member. The slot extends in a direction transverse to the longitudinal axis of the ski and is recessed in the base. The bolt is held in the slot in the running position. The object of the invention is achieved by centering the bolt in the running position by use of a cylindrical guide surface in the base. In the event of a backward fall, the bolt can be moved to a limited extend relative to the base. This movement occurs in a direction substantially perpendicular to the top of the ski against the force of a release spring. In the event of a backward-twisting fall by a skier, the bolt moves relative to the base and is released from the cylindrical guide surface, thereby allowing the sole retainer to move laterally. If the skier falls backward while skiing, the sole retainer is lifted, thereby unlocking the bolt. If there is a backward-twisting fall as well, the sole retainer can swing sideways without delay, ensuring release of the boot sole with little friction. 
     There are mainly two solutions which present themselves for the concrete construction of this toe unit. Of these, the approach set forth in the first embodiment of the present invention is particularly simple. Since the slot that has already been hollowed out must be widened cylindrically in its central region and adapted to the bolt already present. The conical constriction extending behind the shank increases the capability of the screw bolt to swing and facilitates its centering during resetting as well. 
     A compact overall height of the toe unit is ensured by the present invention. 
     The present invention makes it possible that, in the event of a backward-twisting fall by the skier, the sole retainer will not only swing sideways, but will be lifted at its rear end as well. 
     In practice, it has proven advantageous to locate in two planes the centering of the lower end of the bolt, in the running position, and guiding the lower end of the bolt in the event of a twisting fall backwards by the skier. This step makes it possible to make the surfaces governing the guiding and centering sufficiently large so as to reliably prevent them from being deflected by the bolt. 
     Improved centering is ensured by the features of the present invention. 
     The path and the position of the bolt, in the event of a backward fall by the skier, are defined by the present invention. 
     The present invention enables the head of the screw bolt to be locked against axial movement similar to a spherical joint. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Two illustrative embodiments of the subject of the invention are shown in the drawings. 
     FIG. 1 is a vertical cross-sectional side view of a first embodiment of the present invention; 
     FIG. 2 is a partial cross-sectional view taken along line II--II of FIG. 1; 
     FIG. 2a is an enlarged detail of FIG. 2; 
     FIG. 2b is a cross-sectional view taken along line IIb--IIb in FIG. 2a. 
     FIG. 3 is a cross-sectional view taken along line III--III in FIG. 1; 
     FIGS. 4 and 5 correspond to FIGS. 2 and 3, respectively, but with the sole retainer in a horizontally swung position; 
     FIG. 6 is a vertical cross-sectional side view of a second embodiment of the present invention; 
     FIG. 7 is a partial enlarged cross-sectional view taken along line VII--VII of FIG. 6; 
     FIG. 8 is a cross-sectional view taken along line VIII--VIII of FIG. 6; and 
     FIG. 9 corresponds to FIG. 7, but with the sole retainer in a horizontally swung position. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The toe unit depicted in the FIGS. 1-5 is generally designated with the reference numeral 101. The toe unit 101 has a casing 102, to which is attached a carrying member 103, which, a vertical longitudinal median section, is substantially angular in shape. The casing 102 and the horizontal leg 103a of the carrying member 103 are attached in a known manner to the top 100a of a ski 100. The other leg 103b of the carrying member 103 extends perpendicularly to the top 100a of the ski 100 and carries at its upper end an arbor 104 placed in a direction transverse to the longitudinal axis of the ski and in parallel with the top 100aof the ski 100. An angular compensating lever 105 is mounted on the arbor 104, one leg 105a of which extends horizontally and substantially in parallel with the leg 103a of the carrying member 103. Recessed in the leg 105a of the compensating lever 105 is a vertically extending bore 105c through which is passed a screw bolt 106 having a shank 106b and a thread which is engaged in a tap hole in a sole retainer 108. The head 106a of the screw bolt 106 rests on the horizontal leg 105a of the compensating lever 105 and enables the screw bolt to swing in all directions by means of a mounting arrangement similar to a spherical joint. In its set position, the screw bolt 106 is prevented from turning by a torsion spring 119, which is braced on flattened areas underneath the head 106a of the screw bolt 106. The ends of the spring are anchored in the leg 105a of the compensating lever 105. An insert 118, having the form of a U in top plan view, which is pushed onto the screw bolt 106 and enables its head 106a to be mounted with a clearance in the leg 105a of the compensating lever 105, is located beneath the torsion spring 119. There extends behind the lower end section of the shank 106b of the screw bolt 106 a conical constriction 106c, which passes into a cylindrical extension 106d, which carries a coaxially disposed shim 107 held in position by means of a rivet head 106e and which limits the sliding path of the screw bolt 106 and thereby the angle of traverse of the compensating lever 105. 
     A slot 103c is disposed in an upwardly directed bulge of the horizontal leg 103a of the carrying member 103. Slot 103c may, for example, be rectangular. In its mid section, the slot 103c is provided with a cylindrical enlargement 103d designed to engage the cylindrical shank 106b of the screw bolt 106. Furthermore, in its lower section, the limiting wall 103f  of the slot 103c is beveled conically (cf. FIGS. 2a and 2b) so as to enable the bolt 106 to swing sideways in its lifted state. 
     The known structure of the toe unit 101 is as follows: The leg 103a of the carrying member 103, spaced apart laterally from the vertical longitudinal median plane of the toe unit 101, carries two vertical arbors 109, on each of which is mounted a bell-crank lever 110, one leg of which serves as a lateral holding means for the boot sole of a ski boot (not shown) inserted into the toe unit 101. The other leg cooperates with a sliding part 115 to be described more fully hereinafter. 
     A release spring 111 extending along the longitudinal axis of the toe unit 101 and taking the form of a pressure spring is housed in the casing 102. The initial tension of this release spring 111 can be set by means of a sleeve 112 with female thread. The sleeve 112 is screwed onto the threaded section of a pull rod 113, which passes dead center through the release spring 111. Another sleeve 114, acting as a spring plate, is braced on a collar of the sleeve 112. 
     On the end adjacent to the ski boot, the pull rod 113 carries the sliding part 115, which is angular when viewed in a vertical longitudinal median section through the toe unit 101. The pull rod 113 is inserted with its offset end into a bore in the vertically extending leg 115b of the sliding part 115 and riveted. As a result, a pull is exerted on the sliding part 115 by the release spring 111 toward the tip of the ski. The sliding part 115 acts upon each of the two lateral bell-crank levers 110, as well as on the compensating lever 105. 
     The leg 115a of the sliding part 115, parallel to the top 100a of the ski 100 and pointing toward the tip of the ski, has a scale 116 with a slit 117 in which a mark 114a, attached to the sleeve 114, is movably guided. 
     If the skier falls backward, the sole retainer 108 is first lifted, but at the same time the compensating lever 105 is also swung and the screw bolt 106 moved upward until the shim 107 abuts against the bottom of the bulge 103e of the leg 103a of the carrying member 103. The cylindrical shank 106b of the screw bolt 106 is now released from the embrace of the cylindrical enlargement 103d, and the extension 106d of the screw bolt 106 can move, should a back-ward-twisting fall occur, toward one end of the slot 103c. This enables the screw bolt 106 to assume an inclined position as a result of the bevel of the limiting wall 103f of the slot 103c, and facilitates the swinging of the head 106a of the screw bolt 106 on account of the free space between the torsion spring 119 and the insert 118 on the compensating lever 105. 
     Once the ski boot has emerged from the toe unit 101, the release spring 111, by means of the compensating lever 105, returns the sole retainer 108 to its initial position, urging the screw bolt 106 downward. As a result, the cylindrical shank 106b moves into the cylindrical enlargement 103d of the slot 103c, causing the screw bolt 106 to be centered. Thereupon, the sole retainer 108 is again in the position where it is approximately parallel to the top 100a of the ski 100. 
     The embodiment of a toe unit 201 illustrated in FIGS. 6-9 is similar to that described hereinabove. Therefore, the individual components of the toe unit 201 corresponding to the components of the first embodiment are not described separately and are designated with reference numerals higher than 100. 
     Unlike the first embodiment, the slot 220c, is not hollowed out in the leg 203a of the carrying member 203, but rather at a median level of a control block 220. The control block 220 is immovably secured in a recess of the leg 203a and retained by the casing 202 after the toe unit 201 has been assembled. The slot 220c in top plan view is substantially kidney shaped with the concave bend being turned toward the ski boot. A conical depression 220b, followed by a cylindrical opening 220a and thereafter by an opening 220d, is spaced a distance above the slot 220c in the control block 220. In the control block 220, a cavity 220f with a roof 220e is recessed beneath the slot 220c, to which it is parallel. 
     The screw bolt 206 in this illustrative embodiment has a cylindrical shank section 206b located beneath the threaded section. The cylindrical shank section 206b passes over a step into a cylindrical end section 206d. A sleeve 221, which will be described in more detail hereinbelow, is mounted thereon. 
     Here, too, in order to prevent the sleeve 221 from moving downward accidentally, the screw bolt 206 has at its lower end a coaxial shim 207 held in position by means of a rivet head 206e. Furthermore, the roof 220e of the cavity 220f is curved convexly downward in the shape of a circular arc (see FIG. 8), resulting in a well-defined position of the horizontally swung screw bolt 206, and hence also of the sole retainer 208. 
     If the skier falls backward, the sole retainer 208 will first be lifted, but concurrently the compensating lever 205 will also be swung and the screw bolt 206, as well as the sleeve 221, be moved upward until the shim 207 abuts against the roof 220e of the cavity 220f of the control block 220. The cylindrical part 221a of the sleeve 221 is now released from the embrace of the cylindrical opening 220a and, if a backward-twisting fall occurs, the cylindrical end section 221c of the sleeve 221 can move toward either end of the slot 220c, causing the sole retainer 208 to assume an inclined position relative to the longitudinal axis of the ski. Due to the banana or kidney shape of the slot 220c, the sole retainer 208 will also be swung somewhat on an ideal cross axis Y--Y, thereby additionally facilitating removal of the ski boot by the skier from the toe unit 201 in the event of a backward-twisting fall. 
     Once the ski boot has emerged from the toe unit 201, the release spring 211, by means of the compensating lever 205, returns the sole retainer 208 to its initial position, thereby pressing the screw bolt 206 and the sleeve 221 downward. As a result, the conical depression 220b of the control block 220 guides the cylindrical part 221a of the sleeve 221 back into the cylindrical opening 220a of the control block 220 via the conical section 221b of the sleeve 221, which causes the screw bolt 206 to be centered. The apex angle of the conical section 221b of the sleeve 221 corresponds to the apex angle of the conical depression 220b of the control block 220. 
     The invention is not limited to the specific embodiments illustrated in the drawing and described hereinabove. Rather, various modifications thereof are possible without departing from the spirit and scope of the underlying inventive concept. For example, it would be conceivable in the case of the second embodiment to provide the sleeve which is attached to the screw bolt with a hollowconed step, to which is assigned an upwardly directed conical surface of the pedestal. The bolt may also be smooth, with the the sole retainer being automatically adjustable against the force of a pressure spring extending along the bolt. Additionally, the banana or kidney shape of the slot can be utilized in the first embodiment.