US3907316A

US3907316A - Method and devices for releasing a ski boot from the ski

Info

Publication number: US3907316A
Application number: US396723A
Authority: US
Inventors: Hannes Marker; Heinz Korger; Hans-Joachim Steinmetz
Original assignee: Individual
Current assignee: Marker International Co
Priority date: 1972-09-13
Filing date: 1973-09-13
Publication date: 1975-09-23
Anticipated expiration: 1992-09-23
Also published as: DE2244949A1; GB1433162A; DE2328924A1; US3950003A; CA1016207A; CH585563A5; US3940156A; DE2340861A1; FR2198762A1; ATA884672A; DE2328924C2; AU6031373A; DE2244949C2; FR2198762B1; AT330036B

Abstract

A method and a device for automatically releasing a ski boot from a ski on which the boot is mounted, in the event of danger to the skier. The forces acting in a skier''s leg are continuously monitored and are compared, over a predetermined interval of time, with a threshold value. When the forces reach a predetermined value, related to the threshold value, the ski boot is released from the ski.

Description

United States Patent Marker et al.

[ Sept. 23, 1975 [54] METHOD AND DEVICES FOR RELEASING 3.528.672 9/1970 Wunder 280/! 1.35 M A SK] BOOT FROM THE SKI 3,762.735 10/1973 Smolka 280/1135 M 3,776.566 12/1973 Smolka 280/1135 M [75] Inventors: Hannes Marker,

Garmisch-Pflr'tehkirchen; Heinz FOREIGN PATENTS 0 APPLICATIONS 2.014.935 10/1971 Germany 280/1135 M 9 I Germany [7%] Asgi nee Hannes Marker Primary Examiner-David Schonberg g Garmigchmartehkirchcn German Assistant Examiner-Milton L. Smith y Attorney. Agent, or Firm-Flcit & Jacobson [22] Filed: Sept. 13, 1973 [21] App]. No.2 396,723

[57] ABSTRACT [30] Foreign Application Priority Data A method and a device for automatically releasing a Sept. 13. 1972 Germany 2244949 Ski hoot from 11 Ski which the boot is mouhtcdin the event of danger to the skier. The forces acting in a [52] US. Cl. 280/ll.35 M skicris leg are continuously monitored and are 51] int. c1. A63c 9/08 p r a predetermined inierviii of time. with ii 58] Field of Search 280/1135 M threshold valuewhen the forces reach 11 predetermined value, related to the threshold value. the ski [56} References Cited boot is released from the ski.

UNITED STATE PATENT S S 26 Claims, 6 Drawing Figures 3.367.672 2/1968 T0n0zz1 ct al 280/! 1.35 M

l 2\ P50 ,y" i A 3 5 57 l 1 i 1 '1, j l2 l3 1 L 10 L14 7 L51" L51! Sheet 1 0f 3 Sept. 23,1975

US Patent w Ugh w w m km? 222 6 Sheet 3 of 3 Sept. 23,1975

US Patent METHOD AND DEVICES FOR RELEASING A SKI BOOT FROM THE SKI This invention relates to a method of automatically releasing a ski boot from a ski in the event of danger and to devices for performing the method.

For this purpose of automatically releasing a ski boot from a ski, use has so far been made of safety ski bindings in which. when a pressure exceeding a given. possibly adjustable resistance comes into play. a ski boot holder moves from its locking position to its releasing position. thus releasing the ski boot.

In bindings that have so far been known solely from printed publieatons. the resistance means are so selected that they put up a great resistance to jerky loads of short duration. that resistance then being reduced when the loads last longer. Jerky loads are considered to be loads lasting a maximum of about 0.3 seconds. In these bindings the shock energy is absorbed by special shock absorbing facilities. e.g. dampers or inertia masses. Compared with the bindings that are simply ball-locked and also compared with the so-called longstroke bindings. unless they posses a sufficiently high retaining power. such bindings afford considerable advantages. but they obviously cannot be manufactured as easily. cheaply and reliably as necessary for practical purposes.

This invention follows a completely new course and first proposes a method of automatically releasing a ski boot from a ski. in the event of danger which method consists in the fact that pulses acting on the skiers leg are continuously picked up and compared with a predetermined pulse quantity forming a threshold value. and in the fact that the connection between the ski and ski boot is released when that threshold value is reached. In contrast to the prior art this method affords the substantial advantage that the path is not employed as a measuring quantity for the releasing instruction.

It is appropriate when the continuously recorded pulses are related to a predetermined time interval. Furthermore. an arithmetic mean value can be continuously formed from consecutive pulses realtive to a predetermined constant time section and compared with the threshold value.

It is preferable to separately record pulses resulting in different loads on the skiers leg. e.g. torsion or bending loads. and to compare them with one threshold valve respsectively. It may be advantageous when a threshold value for a combined load can be varied as a function thereof.

A device for performing the new method in its simplest form is characterised according to the invention by at least one ski boot holder. a locking feature that fixes the ski boot holder. at threshold value switch influencing the locking feature. a time evaluation element and a pressure recorder.

In a constructive configuration of the device according to the invention the time evaluation element may be an integral element. It is appropriate to use a time evaluation element that takes the form of an inegrating amplifier having an adjustable time constant.

It is preferable to use a capacitive pickup as a pressure recorder. However. it is of course also possible to employ other pressure recorders known per se within the framework of this invention. such as inductive pickups. piezoelectric elements. carbon pressure elements or magnetoelastic pressure gauges In a further development of the invention, which may also be. however. independent of the above-described electronic pressure recording system, the locking feature can be designed with a release mechanism having an actuating element held normally in the unstable state of equilibrium. When use is made of the electronic pressure recording system. the release mechanism element is coupled to a control organ of the threshold value switch.

It is appropriate when the release mechanism comprises a toggle lever held normally in the extended position. When the ski boot holder takes the form of a sole plate held detachably on the ski. a constructive configuration of this underlying idea of the invention is obtained in that the toggle lever is hinged directly with one arm and indirectly via a stop lever with the other arm to the sole plate or'a part firmly connected to said plate end in that there is a ski fitting (i.e. fitting attached to the ski). interacting with the stop lever. In this case the stop lever may have a nose and the ski fitting a notch. It is appropriate when the ski fitting takes the form of a spring-loaded swivel member.

For constructive reasons in particular it is advantageous when the stop lever is designed as a two-arm lever and when the toggle lever is hinged onto the lever arm facing away from the lock. It is also appropriate when there is a stabilising spring which engages on the stop lever and always endeavours to hold the toggle lever in its extended position.

In the development of a device for automatically releasing a ski boot from the ski and sole plate to which it is held in the event of danger. a further configuration of the invention which is similarly independent of the above-described features may consist in the fact that the sole plate is held quasi-rigidly on the ski via a base plate that can be detached together with it from the ski.

It is appropriate when the sole plate is supported by the base plate at four points. Both for constructive reasons and for reasons relating to the manufacturing and safety technicalities it has proved advantageous when the sole plate overlaps the base plate in the form of a box and is secured against lateral movements by spotlike contact points on the base plate.

The base plate can carry a pressure recorder acting on the sole plate for torsion loads and one for bending loads. a time evaluation element and a threshold value switch being assigned to each pressure recorder.

In accordance with the safety bindings which have so far been generally used and comprise a toe holder and a heel holder. sole holders known per se may serve as ski boot holders. It is also just as possible to house at least some of the device parts-in the sole of a ski boot in a manner known per se. i

In a constructive configuration of the electronic system an impedance transformer stage. a carrierl'requency oscillator. a rectifier stage and an arithmetic mean value generator may be provided between the pressure recorder and the threshold value switch.

Both the method according to the invention and a device for releasing a ski boot from the ski are described below in detail with reference to the attached drawings.

FIG. I shows a diagrammatic side view of the device:

FIG. 2 shows a similarly diagrammatic top view ofthe sole plate and base plate of the device according to FIG. I. the representation of the actual ski boot holders and locking feature being omitted;

FIG. 3 is a diagrammatic side view of the locking feature according to the invention in the normal operating state;

FIG. 4 shows the feature according to FIG. 3 instantaneous state upon release;

FIG. shows the feature according to FIGS. 3 and 4 in the instantaneous state when the sole plate engages again after a compulsory release; and

FIG. 6 shows a circuit diagram of the electronic pres sure recording system.

The safety binding illustrated diagrammatically in FIG. 1 has a sole plate 1 on which a ski boot 2 is held in any given suitable manner. being only arbitrarily detachable. A front sole holder 3 which is notshown in further detail is held on the sole plate for adaptation to various boot sole lengths and thicknesses. both the height and length being adjustable. A rear sole holder 4 can pivot around a horizontal transverse axis 5 and is connected firmly to an entering pedal 6. The swivel bolt 7 is spring-loaded and can be swivelled to the right relative to FIG. 1, for example by means of a ski pole tip against spring force. so that sole holder 4 is released and ski boot 2 can be lifted off sole plate 1. When the ski boot is inserted into the binding. the rear sole end encounters entering pedal 6 and swivels the rear sole holder 4 to its locking position. Swivel bolt 7 then catches automatically. Ski boot 2 is then held quasirigidly on sole plate I and. as already mentioned, can be detached only arbitrarily from the sole plate.

The rear sole holder 4 is followed by the electronic pressure recording sytem which is designated by nu meral 50 as a whole and described in detail with reference to FIG. 6.

In accordance with a special feature of this invention sole plate 1 is held on the ski via a base plate 11 that can be detached together with it from ski 1. The front end of the sole plate is equipped with a pocket 12 into which two swing arms 13 of base plate 11 engage. The swing arms are so designed that they take up tensile and compressive forces perpendicularly to the ski plane in the with slight deformations whereas the deformations are relatively great for forces horizontal to the ski plane. Roughly in the range of the rear ski boot and there is a connection between sole plate 1 and base plate 11 via two buffers'l-i. These buffers are sodimensioned in kepping with the swing arms that they too take up tensile and comprssive forces perpednicularly to the ski plane with slight deformations and forces horizontally to the ski plane with relatively large deformations. Sole plate 1 overlaps base plate 11 at least along the two long sides. Roughly in the range of the extension of the leg axis the turning centre between the two plates is formed in that base plate 11 has two lateral cams 15 (see FIG. 2) which are in spot-like contact with the longitudinal side walls of sole plate 1 which are drawn downwards. The transverse forces occurring during the travelling motion which do not cause the leg to twist can thus be picked up.

At its rear end the base plate ll bears a pressure recorder 51' of the electronic pressure recording system. In this case the pressure recorder is a capacitive pickup. The pick-up is in active contact with the rear end of sole plate 1, the contact being such that the torsion forces acting on the sole plate are recorded and measured by the pick-up. Interference quanities are practically eliminated in the torsion measurement by the above-mentioned dimensioning of swing arms 13 and buffers 14. The forces which act on sole holder 4 in a roughly vertical upward direction and occur on frontal loading are transmitted by sole plate 1 to a further pressure recorder 51" which is likewise a capacitive pickup. This pick-up is also connected firmly to base plate 11. The front end of base plate 11 is held detachably on the ski surface by a ski fitting 16. The base plate is held with its rear end on the ski surface by a locking feature which is designated by numeral 20 as a whole and can be unlocked automatically in the event of danger.

In this case locking feature 20 comprises a toggle lever consisting of the two

arms

21, 22 and knuckle joint 23. Arm 21 of the toggle lever is directly hinged onto base plate 11 whereas arm 22 is hinged onto a stop lever 24 which is in turn mounted pivotably on base plate 11. The .toggle lever is normally held in its extended positionand is thus in an unstable state of equilibrium. FIGS. 3 and 5 show the locking feature in various instantaneous states on a larger scale than in FIG. I. Like FIG. 1, FIG. 3 shows the locking feature with the safety binding in the normal operating condition.

Stop lever 24 is designed as an elbow-lever, toggle lever arm 22' being provided on one of the lever arms and the free end of the other lever arm being angled and designed to form a detent nose 25. This detent nose is in active contact with a notch in a swivel member 26 attached to the ski surface. This swivel member is normally held in its locking position under the influence of a pressure spring 27. A stabilising spring 28 which is desinged as a tension spring and hooked at one end onto base plate 11 also engages on that arm of stop lever 24 that is connected to the toggle lever. This stabilising spring is designed firstly to move the toggle lever back to its extended position after the release of base plate 11 from ski I0 and secondly to prevent the toggle lever from folding up unintentionally. Knickle joint 23 forms the actuating element which can be operated by a control organ. for example by the core 30 of a plunger coil which receives an electric pulse as a control instruction from threshold value switch 57 to unlock the

inter-arrested parts

25, 26 for the purpose of releasing base plate 11 and ski boot 2 connected to it via sole plate 1 from ski 10 in the event of danger.

In the normal operating condition detent nose 25 of stop lever 24 is held in non-positive contact in the notch in swivel member 26 both upwardly and toward both sides. Owing to the cranked arrangement of detent mose 25 relative to the turning point of stop lever 24, that arm of stop lever 24 that is connected to the toggle lever describes an upward swivelling motion independent of the load after the emission of an unlocking control instruction. which upward swivelling motion causes the toggle lever to fold up further.

The electronic pressure recording system according to FIG. 6 consists of the following groups: pressure recorder 51, transmission line 52. impedance transformer stage 53, artithmetic mean value generator 56 and threshold value switch 57. The electronic pressure recording system operates in the following manner.

The reaetance of capacitive pressure recorder 51 is proportional to the plate spacing of the pick-up, i.e. the voltage across capacitor C is proportional to the spacing of the pick-up plates and hence to the pressure when the current is impressed. The current is im pressed in that a fixed voltage U determines the current across capacitor C,. In this case the output voltage 5 U is almost equal to the voltage across C with regard to frequency and amplitude. Output voltage U is physically uncoupled and applied to the recitifer via capacitor C In a rectifier stage the AC voltage U is rectified with the aid of a half-wave rectifier.

An arithmetic means value is formed via an integrating amplifier having an adjustable time constant. This arithmetic mean value is the quantity which best describes the pressure and energy curve in the static and dynamic conditions. It is therefore employed for releasing purposes.

Behind stage 56 which forms the arithmetic mean value there is a threshold value switch 57, the reference potential of which fluctuates to the same degree with the operating voltage as the DC voltage component of the measured quantity, i.e. operating voltage fluctuations are thus balanced out directly. The output signal of threshold value switch 57 is directly employed for releasing purposes in the device described. However. it is also basically possible to order the output signal.

Impedance transformer 53 is formed by transistor Q at which an automatic working point adjustment is made by resistors R R and capacitor C In order to amplify the voltage at O as close as possible to l l. the punch-through of Q is reduced via transistor Q. the working point of Q being set by resistors R and R The output signal of Q, is fed' back to stage Q via C The modulation capacity of the impedance transformer stage is increased (amplitude i 6 V at U 9 V) bythe use of coil L, which is resonated with the carrier frequency with capacitor C v The carrier frequency is coupled into impedance transformer stage 53 via transformer Tr and capacitor 1- Carrier frequency oscillator 54 is formed by the complementary COS-MOS transistor pairs 0;, Q,. O the primarysidc of transformer Tr forming the'resonant circuit for the desired carrier frequency together with capacitor C, (approx. 5 kHz). Capacitors C and C, serve to physically decouple the oscillator circuit 0;, Q,. Q Q Resistor R ensures that the oscillator will build up correctly] Resistors R and R serve to limit the current and reduce the current carried by the oscillator Resistors R. and R serve to screen out th e oscillator fundamental.

Rectifier stage 55 is formed by the operation amplifier V.. the current carried by it being governed by re sistor R Rectification occurs at diodes D, and D resistors R and R being the feedback resistors for amplifier V A zero shift-is made via resistor R.; so that the input current of the rectifier stage bccomeszero for a presssure of zero across measuring capacitor C A current corresponding to the pressure measured flows through resistor R to the rectifier stage. physical decoupling being made via capacitor C The output signal of the rectifier stage is transmitted to the arithemetic means value generator 56 via resistor R Capacitor C and resistor R form the feedback of operation amplifier V the current consumption of which is adjusted with resistor R the time constant of the mean value generator being adjustable within wide limits via capacitor C"; and resistor R The working point of amplifiers V, and V; as well as the switching point of amplifier V;, of threshold value switch 57 are adjusted together via voltage divider R R,,. R as a function of the battery voltage. Resistor R serves as a feedback resistance for the threshold value switch, this resistor thereby governing the hysteresis of the threshold value switch in conjunction with resistor R The current consumption of amplifier V;,

is adjusted via resistor R FIG. 4 shows the locking feature in the instantaneous state upon safety release. After the threshold value switch gives the release pulse, base plate 11 which had been held quasi-rigidly on the ski surface beforehand is released spontaneously. Control organ 30 moves the toggle lever with little' force from its extended position and the toggle lever can then fold up promptly practically of its own accord under the influence of the releasing force and detent nose 25 can get free of swivel member 26 Under'the influence of stabilising spring 28 the toggle lever assumesits extended position again immediately afterwards: So that ski 10 cannot run away from the skier after this automatic release of ski boot 2 from s ki 10, a catching element is provided between base plate 11 and ski 10 in a manner that is known and therefore not represented.

After a safety release the skier can step onto the ski again with the base plate which is attached to the ski boot. The front end of the base plate is placed under fitting 16 (FIG. 1) and detcnt nose 25 of stop lever 24 interlocks with swivel member 26 at therear end of the base plate; to this end. swivel member 26 can swivel to the right relative to FIG. 5 against the force of pressure spring 27 before the conditionaccording to FIG. 3 is attained again. v I

During skiing the forces of torsion and of a frontal fall acting on the skiers leg are measured continuously. the paths being practically Zero because the very slight necessary measuring pathsfor pressure recorders 51". 51 are smaller than the elastic material deformations of plates 1 and I1 and of ski boot 2. The pulses acting on the skiers leg are thus picked up constantly. As mentioned in conjunction with the description of the electronic pressure-recording system, these pulses are constantly compared with a predetermined pulse quantity forming a threshold value. When this threshold value is reached. threshold value switch 57 emits a pulse as a control instruction for unlocking.

Interference quantities, especially in the form of friction, are avoided by the quasi pathless form of measurement. This'enables the permissible pulse quantity to be increased because the loads that have so far been accepted for'the skiers leg are fixed with due allowance for unfavorable friction conditions in the conventional binding-systems. A further advantage of the new binding system consists in the fact that the releasing forces do not need to beset individually any more when the permissible pulse quantity is increased. The abovedescribed device according to the invention is simple and sturdy. In addition. it is largely unaffected by tem perature. dirt and icing-up.

Locking feature 20 described with reference to FIGS. 1 to 5 can also be used in principle with toe clamps and heel holders in conjunction with the electronic pressure recording system where it replaces the former locking features of these binding parts. In particular. it is also possible to vary one threshold value as a function of the other for combined loading. Owing to the use of the quasi-rigid lock the friction produced in the former bindings between the ski boot and ski is also avoided here.

In addition. it is also possible to employ the ski boot sole as a housing for the device according to the inven tion. merely one or two simple ski boot holders then being provided on the ski.

One point still to be mentioned is that commercial batteries are used to supply the electronic pressure recording system with energy.

I claim:

I. A method of automatically releasing a ski boot from a ski on which the ski boot is mounted. in the event ofdanger to the skier. the method comprising the steps of: constantly monitoring the forces acting on a skier's leg; generating force signals representative of the forces acting on the skiers leg; developing a thresh old signal representative of the maximum stresses to be tolerated by the skiers leg; developing a control signal whose continuous magnitude is dependent both upon the magnitude and duration of the force signals; comparing said control signal with said threshold signal and releasing the ski boot from the ski upon the control signal reaching a value at least equal to that of said threshold signal.

2. The method of claim 1. wherein an arithmetic mean value is continuously formed from consecutive force signals relative to the duration interval. and compared with the threshold signal.

3. The method of claim 1, wherein force signals leading to different loads on the skiers leg. e.g. torsion or bending loads. are separately recorded and compared with one threshold signal. respectively.

4. The method of claim 1, wherein a threshold signal for a combined load is varied as a function thereof.

5. A device for automatically releasing a ski boot from a ski on which the ski boot is mounted, in the event of danger to the skier. the device comprising: a ski boot holder; locking means for fixing said ski boot holder to the ski; monitoring means in the form of a pressure recorder for continuously monitoring the forces acting on a skiers leg and comprising; first generating means for generating first signals representative of the forces acting on the skiers leg; second generating means for developing a predetermined threshold signal representative of the maximum stresses to be tolerated by the skiers leg; third generating means for developing control signals whose continuous magnitudes are dependent upon both the magnitude and duration of said first signals; comparator means for comparing said control signals with said threshold signal; and a threshold value switch for controlling the locking means and for unlocking the locking means to release the ski boot from the ski upon the control signals reaching a value at least equal to that of said threshold signal.

6. The device of claim 5. wherein the third generating means is an integrator.

7. The device of claim 6. wherein the integrator has an adjustable time constant.

8. The device of claim 5, wherein a capacitive or inductive pick-up serves as the force monitor.

9. The device of claim 5. wherein a piezoelectric element is used as the force monitor.

10. The device of claim 5, wherein a carbon pressure element serves as the force monitor.

11. The device of claim 5. wherein a magnetoeleastic pressure gauge is used as the force monitor.

12. The device of claim 5, wherein the locking means takes the form of a release mechanism having an actuating element held normally in the unstable state of equilibrium.

13. The device of claim 12, wherein the actuating element is coupled to a control organ of the threshold value switch.

14. The device of claim 12, wherein the release mechanism comprises a toggle lever held normally in the extended position.

15. The device of claim 14, comprising a sole plate acting as a ski boot holder and held detachably on the ski. wherein the toggle lever is hinged directly with one arm and indirectly via a stop lever with the other arm to the sole plate and a ski fitting interacting with the stop lever is provided.

16. The device of claim 15. wherein the stop lever has a nose and the ski fitting a notch.

17. The device of claim 15. wherein a spring-loaded swivel member serves as the ski fitting.

18. The device of claim 15. wherein the stop lever is designed as a two-arm lever and the toggle lever is hinged onto the lever arm facing away from the lock.

19. The device of claim 15. comprising a stabilising spring acting on the stop lever.

20. The device of claim 15, wherein the sole plate is held quasirigidly on the ski via a base plate that can be detached together with it from the ski.

21. The device of claim 20. wherein the sole plate is supported by the base plate at four points.

22. The device of claim 20. wherein the sole plate overlaps the base plate in the form of a box and is secured against lateral movements by spot-like contact points on the base plate.

23. The device of claim 20. wherein the base plate carries one pressure recorder acting on the sole plate for torsion loads and one for bending loads and a time evaluation element and a threshold value switch are assigned to each pressure recorder.

24. The device of claim 5, wherein sole holders engage on the toe and heel of the ski boot and serve as the ski boot holders.

25. The device of claim 5, wherein at least some elements of the device are housed in the sole of a ski boot.

26. The device of claim 5. and including an impe dance transformer stage. a carrier frequency oscillator. a rectifier stage and an arithmetic mean value generator between the pressure recorder and the threshold value switch.

Notice of Adverse Decision in Interference In Interference No. 99,297 involving Patent N 0. 3,907,316, H. Marker, H. Korger and H. Steinmetz, METHOD AND DEVICES FOR RELEAS- IN G A SKI BOOT FROM THE SKI, final judgment adverse to the patentees Was rendered May 1, 1978, as to

claims

1, 3, 59, 11, 12, 13, 24 and 25.

[Ofiicz'al Gazette October 17, 1.978.]

Claims

1. A method of automatically releasing a ski boot from a ski on which the ski boot is mounted, in the event of danger to the skier, the method comprising the steps of: constantly monitoring the forces acting on a skier''s leg; generating force signals representative of the forces acting on the skier''s leg; developing a threshold signal representative of the maximum stresses to be tolerated by the skier''s leg; developing a control signal whose continuous magnitude is dependent both upon the magnitude and duration of the force signals; comparing said control signal with said threshold signal and releasing the ski boot from the ski upon the control signal reaching a value at least equal to that of said threshold signal.

2. The method of claim 1, wherein an arithmetic mean value is continuously formed from consecutive force signals relative to the duration interval, and compared with the threshold signal.

3. The method of claim 1, wherein force signals leading to different loads on the skier''s leg, e.g. torsion or bending loads, are separately recorded and compared with one threshold signal, respectively.

5. A device for automatically releasing a ski boot from a ski on which the ski boot is mounted, in the event of danger to the skier, the device comprising: a ski boot holder; locking means for fixing said ski boot holder to the ski; monitoring means in the form of a pressure recorder for continuously monitoring the forces acting on a skier''s leg and comprising; first generating means for generating first signals representative of the forces acting on the skier''s leg; second generating means for developing a predetermined threshold signal representative of the maximum stresses to be tolerated by the skier''s leg; third generating means for developing control signals whose continuous magnitudes are dependent upon both the magnitude and duration of said first signals; comparator means for comparing said control signals with said threshold signal; and a threshold value switch for controlling the locking means and for unlocking the locking means to release the ski boot from the ski upon the control signals reaching a value at least equal to that of said threshold signal.

6. The device of claim 5, wherein the third generating means is an integrator.

7. The device of claim 6, wherein the integrator has an adjustable time constant.

9. The device of claim 5, wherein a piezoelectric element is used as the force monitor.

11. The device of claim 5, wherein a magnetoeleastic pressure gauge is used as the force monitor.

15. The device of claim 14, comprising a sole plate acting as a ski boot holder and held detachably on the ski, wherein the toggle lever is hinged directly with one arm and indirectly via a stop lever with the other arm to the sole plate and a ski fitting interacting with the stop lever is provided.

16. The device of claim 15, wherein the stop lever has a nose and the ski fitting a notch.

17. The device of claim 15, wherein a spring-loaded swivel member serves as the ski fitting.

18. The device of claim 15, wherein the stop lever is designed as a two-arm lever and the toggle lever is hinged onto the lever arm facing away from the lock.

19. The device of claim 15, comprising a stabilising spring acting on the stop lever.

20. The device of claim 15, wherein the sole plate is held quasi-rigidly on the ski via a base plate that can be detached together with it from the ski.

21. The device of claim 20, wherein the sole plate is supported by the base plate at four points.

22. The device of claim 20, wherein the sole plate overlaps the base plate in the form of a box and is secured against lateral movements by spot-like contact points on the base plate.

23. The device of claim 20, wherein the base plate carries one pressure recorder acting on the sole plate for torsion loads and one for bending loads and a time evaluation element and a threshold value switch are assigned to each pressure recorder.

26. The device of claim 5, and including an impedance transformer stage, a carrier frequency oscillator, a rectifier stage anD an arithmetic mean value generator between the pressure recorder and the threshold value switch.