The invention relates to a clutching device for a hoisting machinery for doors or the like, said machinery having a pri¬ mary shaft connected via a gearing to a driving motor, and a secondary shaft carrying a hoisting means, said clutching device including between said secondary shaft and said gearing, coupling means for disengaging said secondary shaft siutably . for manual operation, said coupling means being provided with first and second axially mutually movable clutch members, said second clutch members, which preferably is movable in the direction of the secondary shaft against the force of a spring load, comprises at least one pair of contact flank faces acting preferably essentially perpendicularly against the direction of the shaft radius, said faces having different extensions in the direction of said shaft.

The invention relates also to a method for the controlling of the movement .of the secondary shaft of a hoisting machinery or the like, wherein for the manual or the like operation the secondary shaft is disengaged from the driving motor with the aid of an essentially tapered-tooth claw clutch means, which is preferably movable in the direction of said secondary shaft in such a way that a clutch disc mounted torsion resis±ibly on said secondary shaft is moved in the direction of said shaft. The invention further relates to the use of the partial dis¬ placement of a tapered-tooth clutch member in connection with hoisting machinerys for the disengaging of the driving motor from the hoisting means in such a way that in the disengaged mode the relative rotation of the hoisting means is possible in one direction but is still prevented in the other direc¬ tion, whereby in the normal operation mode the driving motor and the hoisting means are in immobile contact with each other.

The hoisting machinery for doors is generally composed of a driving motor coupled to the primary shaft of a gearing, such

as for example a worm gear or the like, and of support means for the door or the like in load bearing connection with the secondary shaft of said gearing. The driving machinery gene¬ rally consists of an electromotor or the like and for the case of a disruption in the power distribution one should be able also to operate the door manually at least in such a way that the door always can be safely opened. In these situations the driving motor normally has to be rotated by hand which is generally an extremely slow process which moreover is very difficult- to accomplish .technically. Alternatively the secon¬ dary s a£t has to be disengaged from the gearing and the manual operation can be performed directly at the secondary shaft or the door itself without, however, the machinery pre¬ venting the movement of the door. In the normal operation mode the gearing, which is generally of a self-retaining type, supports the door or the like directly via the secondary shaft, whereby the weight of the door despite counter balancing generally causes a load acting on said gearing. In case the door at the moment of disengagement is for example ϊn a hoisted position there exists, however, the risk that at the disengagement the door may crash down e.g. because of being out of balance. So far this has been prevented by the con¬ struction of complicated brake means or arresting devices controlling the movement of the door which forms the load at the moment when the secondary shaft is disengaged from the gearing. The object of the invention is to provide a simple clutch solution which in all situations enables the opening of the=- dσor in an emergency. It is also the object of the in¬ vention to provide a solution which prevents the door from freely crashing down, by maintaining the driving motor to support the door at all times.

According to the invention this is accomplished by a clutch connected to the hoisting machinery in the way disclosed in the appended claims. In the normal operation mode according to the characteristic features of the invention both contact flank faces, due to the mutual axial positions of the clutch members, extend into an interlocking engagement carrying the

load in opposite directions, said engagement being formed between said contact flank faces and the corresponding faces of at least one notch of in one of the opposite clutch mem¬ bers, whereby in the disconnected mode one of the contact flank faces of each flank pair still, preferably by spring force, aims at said interlocking engagement preventing the rotation in one direction while the other contact face of the notch meets a tapered front face enabling slipping in the opposite direction.

Thus one clutch member, which is preferably movable in the direction of the secondary shaft against a spring force, com¬ prises at least one pair of contact flank faces extending preferably essentially radially in relation to said shaft and acting perpendicularly to this direction, said contact faces having different axial extensions so that depending on the mutual axial positions of the clutch members either both con¬ tact flank faces of each pair extend into an interlocking engagement carrying loads in opposite directions, said engage¬ ment being made with the corresponding contact faces of at least one notch in the other clutch member, or only one of the contact faces respectively of each pair is in such engagement.

According to a preferred embodiment of the invention the dis¬ engaging displacement is performed only to such an extent that of the unequal flanks of the clutch disc teeth, which in their peripheral cross sections preferably have the form of ortho¬ gonal trapeziums with unequal sides having flanks which are at least approximately parallel with the axis, only the shorter one of said flanks is disconnected from the engagement carrying the load in one direction, said engagement being with the corresponding flank of a notch in a counter piece, while the second flank of said tooth remains still at least partly in an axial position which enables opposite direction load bearing contact with the second flank of the same notch.

In the following the invention will be described in more detail with reference to the drawings, wherein

Fig 1 shows a cross section of the hoisting machinery ac¬ cording to the invention, and

Fig 2 shows a cross section of a clutch disc according to one embodiment of the invention.

In the .embodiment shown in Fig 1 there is a primary shaft 2 provided in a housing 1, said shaft having a toothed worm 3. The primary shaf.t 2 is rotated by a driving motor (not shown). In interlocking engagement with the toothed worm 3 there is a worm wheel 5 freely rotating on the secondary shaft 4. The secondary shaft 4 carries the actual load such as a door or the like via not shown means. In this embodiment the worm wheel 5 simultaneously forms one member of the clutch between the gearing and the secondary shaft 4 so that the worm wheel 5 includes one or- several notch(es) 6. Each notch 6 is provided with two active contact faces 7 and 8. The secondary shaf 4 includes as the second member of the clutch a clutch disc 9 provided with one or several teeth 10, which extend into interlocking engagement with the notch 6. Each tooth 10 com¬ prises a pair of load carrying contact flank faces 11 and 12, which at gearing function inter esh into load carrying engage¬ ment with contact faces 7 and 8, respectively of the notch 6. In this position one contact 7-11 carries the load in one direction and the other contact 8-12 carries the load in the opposite direction.

According to the invention opposing contact face pairs 11, 12 of each tooth 10, include one contact flank face 12, having an axial extension which is longer, according to one embodiment preferably twice as long as the axial extension of the other contact face 11 of the same tooth. In practice this means that the front face 13 of the tooth 10 is tapered, whereby the cross section of the tooth in the axial peripheral direction forms a orthogonal trapezium with unequal sides.

The clutch disc 9 itself is mounted resistibly to torsion, e.g

with the aid of a slot wedge or the like to the shaft 4 but is movable in the direction of said shaft 4. In the preferred embodiment of the invention a spring 14 presses the disc 9 against the wheel 5 so that said one or preferable several teeth 10 settle into the corresponding notches 6 in the wheel 5. The clutch disc 9 is then in such a position that both contact faces 7-11 and contact faces 8-12 can be ^' charged with a load, whereby the motion of the secondary shaft 4 is completely determined by the motion of the primary shaft 2 and thus of the driving motor.

In order to enable the hoisting of the door in an emergency also independently of the driving motor, shafts 2 and 4 have to be disengaged. At the same time it is necessary to maintain a sufficient contact between the shafts 2 and 4 in the oppo¬ site direction so that the door cannot fall down even though the clutch were to be opened when the door is in an elevated position. Provided that a sufficient contact is maintained the self-retaining nature of the worm gear in the described embodiment, or for example separate brake members, prevent the door from falling.

Disengagement is provided by forcing the clutch disc 9 with the aid of not shown displacement means to move out of direct contact with the worm or cog wheel 5. According to the in¬ vention this forcing is provided to such an extent, that one contact flank face 11 of the clutch disc 9 is no longer in interlocking engagement with the contact face 7 of the notch 6 in said wheel 5. The forcing, however, cannot in normal cases extend so far that also contact face 12 were to move out of engagement with the contact surface 8. When the secondary shaft 4 thereafter is turned with the aid of not shown manual¬ ly operated means in a direction opening the door, the tapered front face 13 of each tooth 10 will get no hold on the notch 6 in the wheel 5, but will only press the clutch disc even further against the spring 14, whereby the tooth 10 will move to the following notch 6 of the wheel 5 and the secondary shaft 4 can rotate correspondingly.

In case the door for some reason were to show a tendency to move downward by its own weight, which can happen for example, at the moment of disengagement or in case the grip at the manually operated means does not hold, each contact flank face 12 is still in engagement with the contact face 8 of the notch 6 due to the action of the spring 14 and in spite of the clutch disc displacement means. Thus the movement of the secondary shaft 4 and thus of the door in the downward direc¬ tion is prevented. Thus as a result of the unequally long tooth flanks the solution according to the invention in dis¬ engaged mode functions as a clutch which in one direction is freely moving and in- the other direction is immobile, while in the engaged mode the clutch is completely immobile.

According to another embodiment shown in Fig 2 the axially longer extending contact flank face 12 of the clutch disc 9 is divided into parts 12a and 12b which are staggered in the direction of the periphery, wherefore the peripheral dimension of the tooth 10 changes in the direction of the shaft 4. The width of the tooth 10 measured from contact face 11 to contact face 12a preferably corresponds approximately to the width of the notch 6 in the wheel 5 at said point, but the width of the tooth 10 in the direction of the shaft 4 towards the wheel 5 as measured from the contact face 11 to the contact face 12b is slightly smaller than the width of the notch 6. Thus the tooth 10 fits into the notch 6 slightly more loosely when the clutch disc 9 is displaced into disengaging position from the wheel 5 in the direction of the shaft 4. This solution has the advantage that it facilitates the settling of the tooth 10 into the notch 6 in a situation when the shaft 4 together with its clutch disc 9 due to a sudden charge tends to rotate quickly while the wheel 5 functioning as a counter piece remains still in its original position. The extension of the flank part 12b in the axial direction corresponds preferably to the corresponding extension of the tapered front face 13.

The peripheral dimension between the contact faces 7, 8 of the

notch 6 or the like in the counter piece 5 is preferably essentially the same as, or greater by the amount of the tolerance than the corresponding dimension between the contact faces 11 and 12, 12a of the clutch disc 9 and materially greater than the dimension between the contact face 11 and the eventual second flank part 12b.

In the embodiment shown in Fig 2 the outer part of the tapered front face 13 of the tooth 10 on the clutch disc 9 includes a beveled part 15, the surface of which essentially forms the mirror image of the rotation surface 16 of wheel 5, which rotation surface is directed towards the clutch member. The object of such a bevelling is to prevent the sharp edge of the tooth 10 from digging into the worm wheel 5 functioning as a counter piece and preferably being made of bronze.

Within the scope of the invention it is also possible to construe the displacement means of the clutch disc in such a way that with special measures the clutch can be completely disengaged for example for maintenance or the like purposes.

In the foregoing there has been exemplified embodiments wherein the teeth 10 are situated in the clutch disc 9 and the notch 6 in the wheel 5 but the arrangement can naturally be the opposite. Likewise the clutch according to the invention can be adapted in connection with another type of gearing solution, the full benefit of the invention still requiring that the rotation of the gear from the secondary shaft is not possible or at least causes great resistance.

In the foregoing there has been described principally embodi¬ ments wherein the teeth 10 have a more or less clearly defined radial reach in the lateral direction with respect to the secondary shaft 4, said reach defining the contact faces 11 and 12. The scope of the invention, however, covers also embodiments wherein the teeth 10 are formed as tapered cut round tenons. According to another embodiment of the invention the contact faces of the teeth 10 and the contact faces 7, 8

and 11, 12 respectively of the notch 6 in the wheel 5 are paired parallel surfaces. The production of such teeth 10 and notches 6 is production technically advantageous. Although the tapered front face 13 of the tooth 10 in the theoretically most preferred embodiment were to form a helical surface it is likewise sometimes advantageous to make the front face 13 into a planar tapered surface.