The present invention relates to a safety device for an apparatus provided for lifting and lowering loads and comprising at least one column, an arm attached to this column and pneumatic, hydraulic or motor means for moving said arm up and downwards.

Such devices are known. A field wherein they are regularly used is the field of lifting and lowering patients. The invention is however not limited to this field. For example, lifting and putting down loads of whatever which kind and in general exerting a push or pull force on a mechanical component fall also within the scope of this patent application.

In apparatus or devices of the most common type for lifting and lowering patients, the arm is hingedly connected to the hereabove mentioned column. Lifting and moving the arm downwards is realized, in many cases, by a motor although hydraulic or pneumatic drives may also be used.

The arm is moved upwards and downwards by a rod which is itself partially shaped as a spindle rod. When use is made of an electromotor with reducer, it is not excluded that the motor does not react correctly to one command or another. In particular, there is especially an important risk thatwhen the arm is moving downwards and when the motor which actuates this arm is not stopped in time (as a consequence of a human mistake or of a technical malfunction), the arm will continue to move downwards which may cause serious injuries to the patient.

It is clear that when this problem is posed in the device for hoisting and/or putting down goods, these goods can be heavily damaged when the arm is not stopped in time during its downward motion or cannot be stopped at all.

An object of the present invention is now to provide a safety device which solves this problem and which offers a large safety in those cases wherein a drive motor or any other drive means of such an arm does not react in time to a received command or when the command is simply not given so that the arm continues to move downwards with a large force.

The intention is therefore to provide a device of the hereabove described type which can be stopped when the arm of the apparatus meets an obstacle during its downward movement.

In order to enable this according to the invention, said means act upon a rod which slides telescopically in a hollow tube or upon a hollow rod which slides around a loose rod in order to lift said arm and to lower it in such a manner that when said arm is held back either directly or indirectly by an obstacle, the rod and the hollow tube, on the one hand, and the hollow rod and the loose rod, on the other hand, can slide with respect to one another so as to prevent a further downward movement of the arm when said arm is held back for example by an operator.

Other details and advantages of the invention will become apparent from the following description of a safety device for an apparatus provided for lifting and lowering loads according to the invention. This description is only given by way of example and does not limit the invention. The reference numerals relate to the annexed figures.

• Figure 1 is a side elevational view which is kept schematically, of an apparatus for lifting and lowering loads according to the invention.
• Figure 2 is a view analogous to figure 1 wherein the arm of the apparatus meets an obstacle.
• Figure 3 shows, on a larger scale, the relative position of a tube with respect to a rod which can be moved up and downwards (position without obstacle).
• Figure 4 shows, on a larger scale, the relative position of a tube with respect to a rod which can be moved up and downwards (position with an obstacle).
• Figure 5 shows, on a larger scale, the relative position of a rod with respect to a hollow tube which can be moved up and downwards (position without an obstacle).
• Figure 6 shows, on a larger scale, the relative position of a rod with respect to a hollow tube which can be moved up and downwards (position with an obstacle).
• Figure 7 is, on another scale, a front elevational view which is kept schematically of a variant embodiment of the apparatus according to the invention.

The safety device shown in these different figures belongs to an apparatus for lifting and putting down loads.

As in the example setforth in the preamble, there will be discussed here especially the case of an apparatus destined for lifting and putting down patients. Such an apparatus consists amongst others of a column 1 with a hinged arm 2. This arm is lifted according to the principle of a lever of the third order. Lifting the arm 2 is realized by making use of an electric motor 3 which drives in the cylinder4 a jack rod or spindle which exerts the necessary pressure onto the rod 5 to lift the arm 2.

According to the invention, this can now be embodied in one of the two following ways.

According to the first embodiment (figures 1, 2, 3, 4 and 7) the rod 5 is pushed out of the cylinder 4 and slides into a hollow tube 6 which cooperates tel- escopicallywith this rod. Atthe top, the tube 6 is hingedly connected in 7 to the arm 2.

Upon lifting the arm 2, the uppermost extremity of the rod 5 pushes therefore against the bottom 6' of the hollow tube 6. During the downward movement of the arm 2, it pushes due to its own weight onto the hollow tube 6 which, in its turn, rests with its bottom 6' upon the rod 5. In case the arm 6 meets now an obstacle and in case the electric motor 3 cannot be stopped, the operator can still hold back the arm which however does not prevent the rod 5 from being displaced further downwards and from continuing to move separately from the hollow tube 6, as shown anyway in figure 4, when the electric motor 3 continues to rotate

When mention is made of an obstacle, reference is made either to the patient himself or to the bed or the chair of this patient, but this may also be a furniture component and in the case wherein the motor cannot be stopped, the operator may simply stretch out his arm and hold back the hinged arm 2 of the apparatus. Aforced further downward movement of the arm 2 has in no way to be feared. In figure 2 the obstacle is formed by the patient himself but this is of course a very schematic and simplified representation of the facts. In many cases the patient lies into a carrier frame and this carrier frame is then intended to be put onto his bed so that a further downward movement of the arm 2 may cause very serious injuries.

The principle according to which the second embodiment has been invented is very related to the first one. According to the second embodiment, the rod 5 is replaced by a hollow rod 8 (figures 5 and 6), while the hollow tube 6 from the embodiment according to figures 1 to 4 is replaced by a loose rod 9 having a cylindrically shaped abutment 9', the uppermost portion of the hollow rod 8 can push against during the upward movement of the arm 2.

In case the arm 2 meets now an obstacle as it has just been explained, the hollow rod will simply continue to move downwards with respect to the loose rod 9. In this case also, the operator of the device which observes a malfunction in the control of the electric motor, can simply hold back the arm 2. Aforced drive and therefore a continued downward displacement of the loose 9 is therefore not to be feared.

In figure 7 there is shown a variant wherein two columns 10 are present along which an arm 11 can be displaced up and downwards. The components which enable to up and downward movement of the arm 11 are here of the type according to figures 5 and 6 wherein a loose rod 9 can be displaced in a hollow rod 8. Also in this case an intervention is possible to prevent the arm 11 from moving further downwards against the will of the operator since upon a further continued rotation of the electric motor 3, the hollow rod 8 will be pulled further downwards and will further displace along the loose rod 9 so that when the arm 11 is hold back manually, this can be realized by the intervention of one or two operators.

Although the invention is described in view of the problems involved with lifting and putting down a patient, it is clear that the patent application covers also the field wherein similar problems can be observed, not only upon lifting and putting down loads but also upon exerting a pulling force on condition however that the arm 2 or the arm 11 are moved downwards by their own weights, i.e. by gravity.

It is clear that the invention is not limited to the hereabove described embodiments and that many modifications could be applied to these embodiments without leaving the scope of the present patent application.