GB2071611A - Driving device, for lifting and lowering the platform of a bed or couch - Google Patents

Abstract

A driving device, for lifting and lowering the platform of a bed or couch, comprises a support cylinder 1, an axially movable working rod 2 extending into and from the cylinder, the cylinder having a driving section A and a locking section B, at which the rod can be driven and locked, respectively, there being a movable driving piece 3 loosely fitted in said driving section, a driving shaft 4, with a driving protrusion 6 for pushing 3 against the action of a return spring 5, thus driving said working rod forward, a locking piece 7 which is fitted loosely about rod 2 and is pivotable, and a locking spring 8 in said locking section arranged so that when said driving piece 3 is moved backward by said return spring, said locking piece 7 is urged by the said locking spring 8 to engage and lock said rod 2, and including means, e.g. pins 10, to pivot the locking piece to a position in which it does not lock the rod and thus allows it to move backward. <IMAGE>

Description

SPECIFICATION Driving device for lifting and lowering the platform of a bed or couch The present invention relates to a new driving device for lifting and lowering the platform of a bed or couch, by which is meant any surface for a person such as a patient to rest, sleep, be examined, be treated, or be carried on.

Various arrangements for lifting and lowering such a platform are known, and it is known for the platform to be divided into several portions so that desired portions can be pivoted or lifted independently in desired directions. Thus the platform can undulate as a whole or the structure supporting the platform can be adjusted to lift said platform as a whole; or the structure can lift the head or foot of the platform or lift it at one side and/or lower in on the other side. With such a bed, a lifting mechanism is installed below said platform, and comprises a lifting member to convert the displacement applied to it for lifting said platform or bedstead, and a driving device for applying such displacement to said lifting member.

A known driving device for applying such displacement to a lifting member is described, for example, in U.S. Patents Nos. 3,01 5,113 and 3,174,161. In this device, an internal thread provided at one end of a hollow working rod is engaged with an external thread of a rotatable shaft, and the externally threaded shaft is rotated by a crank handle, or geared motor to displace the working rod linearly. Although such a device is widely used, it has the disadvantage that the friction between the internal thread and the external thread leads to considerable resistance to manpower operation, while for the frictional force to be decreased the cost must be raised. Also if said external thread shaft is alternatively rotated by a geared motor, the cost will be raised.In addition to such a device, it is known to use a pneumatic or hydraulic cylinder as the driving device, but this requires an air compressor or hydraulic pump as a pressure source, and furthermore various vaives such as a pressure reducing valve, pressure regulating valve and control valve. Such a device as a whole, together with its piping, requires a lot of space, and makes the cost high, and also involves problems of noise generation and maintenance.

According to the present invention there is provided a driving device for lifting and lowering the platform of a bed or couch, such device including a support cylinder, an axially movable working rod extending into and from the cylinder, the cylinder having a driving section and a locking section at which the rod can be driven and locked, there being a movable driving piece loosely fitted in said driving section, a driving shaft provided adjacent one side of said driving piece, a driving protrusion on said driving shaft for pushing said driving piece against the action of a return spring so that the driving piece can be moved forward by said driving protrusion and backward by said return spring, and said driving piece being engageable with said rod for driving said working rod forward upon the forward movement of said driving piece, a locking piece which is fitted loosely and pivotable and a locking spring in said locking section arranged so that when said driving piece is moved backward by said return spring, said locking piece is urged by the said locking spring to engage and lock said working rod, and including means to pivot the locking piece to a position in which it does not lock the working rod and thus allows said rod to move backward.

The driving device of the present invention does not use such an expensive drive source as a geared motor, air compressor or hydraulic pump, but allows manual driving, and effective utilization of the space below the bed, etc. and low cost to be attained. Furthermore, the driving device of the present invention keeps the influence of frictional force small compared with the above described known device so reducing the manual load. For driving, since a lever or the like can be reciprocated, the operation can be effected by hand or foot, thereby allowing a great range of design.

The invention will be more clearly understood from the following description which is given by way of example only with reference to the accompanying drawings, in which: Figs. 1 A and 1 B show a driving device of the present invention schematicaliy, 1 A being an illustrative front view partially cut away to show the inside as a section, and 1 B being a plan view; Fig. 2 is an enlarged illustrative longitudinal section to show part of the structure and action of a first embodiment of driving device; Figs. 3A and 3B are enlarged illustrative longitudinal sections to show part of the structure and action of a second embodiment of driving device; Figs. 4A and 4B are enlarged illustrative longitudinal sections to show part of the structure and action of a third embodiment of driving device;; Figs. 5A and 5B are respectively an enlarged illustrative partial pian view and an enlarged illustrative partial longitudinal section of part of a device of the invention showing the action of the leaf spring of the third embodiment shown in Figs. 4A and 4B; Figs. 6A and 6B and Fig. 7 are illustrative front views showing the driving device of the present invention applied to a bed; Figs. 8A and 8B are respectively an illustrative perspective view and an illustrative longitudinal section to show the structure and action of an embodiment of a lever used in a driving device of the present invention; Fig. 9 is an illustrative front view to show use of the lever shown in Figs. 8A and 8B, with the driving device of the present invention applied to a bed.

In the drawings, symbol 1 indicates a support cylinder containing a working rod 2 extensibly, and said support cylinder has, at one end, a driving section A and a locking section B of said working rod 2. In said driving section A, said working rod 2 has a driving piece 3 loosely fitted movably, and a driving shaft 4 is provided near to one side of said driving piece 3. On said driving shaft 4, a driving protrusion 6 is formed, to push said driving piece 3 at its one side "a" against the resilience of a return spring 5, so that said driving piece 3 may be moved forward by said driving protrusion 6 and backward by said return spring 5.In said locking section B, said working rod 2 has a locking piece 7 loosely fitted pivotally movably with one side held, and a locking spring 8 is provided, so that when said driving piece 3 is moved backward by the return spring 5, said locking piece 7 may be kept inclined by the resilience of the locking spring 8, to lock said working rod 2. The locking piece 7 can be supported by a groove 9 as shown in Fig. 2 or by a protrusion 9' as shown in Fig. 3, or by a hinge though not illustrated.

In the state shown by solid lines in Fig. 2, if the driving shaft 4 is rotated clockwise in the drawing by a proper mechanism as described later, the driving protrusion 6 formed on the driving shaft 4 pushes said driving piece 3 at its one side against the resilience of the return spring 5. Since the driving piece 3 is pushed only at one side in this way, to move leftward in the drawing in its inclined state, it locks the working rod 2 according to the principle of so-called inclination lock, to move said working rod 2 leftward in the drawing, extending said working rod 2 from the support cylinder 1.In this case, the locking piece 7 is inclined by the resilience of the locking spring 8, being in contact with the working rod 2, but since the working rod 2 moves in the direction (leftward in the drawing) to erect the inclined locking piece 7, the working rod 2 is not locked by the locking piece 7, not causing the movement to be prevented. After the driving piece 3 is moved forward to the end of movement in this way, the driving shaft 4 is rotated in the other direction, to move the driving protrusion 6 back, and this causes the driving piece 3 to be moved back to the starting point of forward movement by the resilience of the return spring 5. In this case, since the driving piece 3 is supported at one side by the driving protrusion 6 which is being moved back, it inclines in the same direction as in case of moving forward, by the resilience of the return spring 5.

However, since said driving protrusion 6 is moved back in the direction to erect the inclined driving piece 3, said driving piece 3 is not locked by the working rod 2, not being prevented from moving backward. In this case, though said locking piece 7 does not lock said working rod 2 in the direction in which the working rod 2 is moved by the forward movement of the driving piece 3 as mentioned before, it locks the working rod 2 in the other direction according to the principle of inclination lock, to prevent the movement in such direction.

Thus, in the forward movement of the driving piece 3, the working rod 2 is moved forward, and in the backward movement. the working rod 2 is prevented from returning by the locking piece 7.

Therefore, by repeating the forward and backward movement of said driving piece 3, the working rod 2 can be driven in one direction intermittently against the load, to be gradually extended from the support cylinder 1. To shorten the working rod 2 extended from the support cylinder 1 in this way, the locking piece 7 can be pivotally moved against the resilience of the locking spring 8 by a proper mechanism, to be erected, releasing the lock between the locking piece 7 and the working rod 2. Thus, the working rod 2 can be moved in the load direction, or be shortened into the support cylinder.

Embodiments of the mechanism for pivotally moving said locking piece 7 against the resilience of the locking spring 8 are described below.

In the first embodiment shown in Fig. 2, the locking piece 7 is pulled at the other side, by a tension wire means W, to be pivotally moved. This composition has a feature that said locking piece 7 can be pivotally moved independently of said driving shaft 6.

On the contrary, in the second embodiment shown in Figs. 3A and 3B and in the third embodiment shown in Figs. 4A and 4B, said locking piece 7 is pivotally moved in relation with said driving shaft 4. The structure and action are as described below.

In Figs. 3A and 3B, Figs. 4A and 4B and Figs.

5A and 5B, symbol 10 indicates a releasing bar provided in the rear of said driving protrusion 6 and in front of said locking piece 7. Said releasing bar 10 is moved toward said locking piece 7, by moving said driving protrusion 6 backward beyond the position corresponding to the start point oC: the forward movement of said driving piece 3.

In this composition, if the working rod 2 is driven by the action mentioned before, the driving protrusion 6 is stopped at a position before it pushes the releasing bar 10 when the driving piece 3 is moved backward, in order that the locking piece 7 may not be pivotally rotated to be erect by said releasing bar 10.

If said driving shaft 4 is rotated to move the driving protrusion 6 further backward beyond said stop position reached during driving, said driving protrusion 6 contacts, at its rear side, the releasing bar 10, to move it. Therefore, the locking piece 7 is pivotally moved to be erect by said releasing bar 10 against the resilience of the locking spring 8, to unlock the working rod 2. Thus, in this state, the working rod 2 can be moved in the direction reverse to the driving direction, and moves in the load direction as illustrated, being shortened into the support cylinder 1.

As described above, when the working rod 2 is driven, the driving protrusion 6 is stopped at a position before it pushes the releasing bar 10, and when the working rod 2 is moved backward, it is moved further backward beyond said stop position. For such operation, for example, a proper stopper can be provided in correspondence to the stop position, so that during driving, said stopper is actuated, to prevent the backward movement, and for returning of the working rod 2, said stopper is released, to allow the backward movement. As another composition, a load by the resilience of a spring can be applied for the backward movement beyond said stop position, so that the driving protrusion 6 may be stopped at said stop position by said load during driving, and may be moved further backward by a force larger than said load, during returning.Any other composition can be easily adopted for such operation.

A preferable embodiment of the latter composition in which said operation can be made by the resilience of a spring is shown in Figs. 4A and 4B and Figs. 5A and 5B. In the drawings, symbol 11 indicates an arcuately curved leaf spring provided between the tip of said releasing bar 10 and said locking piece 7, with its convex side turned toward said releasing bar 10. The leaf spring 11 is set as described above, for example, being fitted into fitting grooves 12 formed on the side wall of the casing of the locking section B as illustrated.

In this composition, as mentioned before, for driving the working rod 2, when the driving piece 3 is moved backward, the driving protrusion 6 pushes said releasing bar 10, and must be stopped before the position where the locking piece 7 is actuated, so that the locking piece 7 may not be pivotally rotated to be erected by said releasing bar 10. In this embodiment, since the arcuately curved leaf spring 11 is provided between the tip of the releasing bar 10 and the locking piece 7, with the convex side turned toward the releasing bar 10, said leaf spring 11 generates a large repulsive force when the releasing bar 10 is moved toward the locking piece 7, and the repulsive force can easily and reliably stop the driving protrusion 6, preventing false operation.

When the driving shaft 4 is rotated, the driving protrusion 6 can be moved backward beyond the stop position reached during driving, to move the releasing bar 10 toward the locking piece 7 against the repulsive force of the leaf spring 11. If the releasing bar 10 pushes the locking piece 7 through the leaf spring 11, to pivotally rotate the locking piece 7 against the resilience of the locking spring 8, the inclined locking piece 7 is erected, unlocking the working rod 2. Therefore as mentioned above, in this state, the working rod 2 can move in the direction reverse to the driving direction, to be shortened into the support cylinder 1.In this case, since the leaf spring 11 is curved arcuately as illustrated, to be convex toward the tip of the releasing bar, said repulsive force is very large at the beginning, but when the convex portion in contact with the tip of the releasing bar 10 becomes flat with the movement of the releasing bar 10 as illustrated, the repulsive force becomes very small, allowing sudden bending by said releasing bar 10. Such sudden change of status is transmitted to the hand or foot of the operator through a lever 1 3 described later.

Therefore, if such sudden change of status is made to correspond to the completed erect action of the locking piece 7, the operator can confirm whether the locking by the locking piece 7 is released, by a reaction to him during operation. Thus, the unlocking can be effected definitely, and the working rod 2 can be moved backward smoothly.

In this composition, when used for a bed 14 or any other thing for sleeping or resting on, the driving device of the present invention is connected to a lifting member for lifting and lowering the platform 1 5 or bedstead 1 6 of the bed, to make a lifting mechanism of the platform 1 5. Embodiments are described below. Fig. 6 shows an example, in which the root of the support cylinder 1 is fitted to a bedstead 16, and the tip of the working rod 2 is connected to a lifting member 18 provided below a movable platform portion 17, whereby said driving piece 3 is reciprocated, to extend the working rod 2 from the support cylinder 1, raising the movable platform portion 1 7 pivotally by the lifting member 1 8 against gravity.In this example, the driving shaft 4 reciprocating the driving piece 3 can be driven by a lever 13 directly fitted to the driving shaft 6 as shown in 6A, or the lever 13 can be connected to the driving shaft 4 through a proper motion transmitting mechanism M such as a link work, with said lever 13 set at a proper position below the bed 14 as shown in 6B. Fig. 7 shows another example, in which the bedstead 1 6 and a base 19 are connected by parallel links 20, to allow said bedstead 1 6 to be lifted and lowered in parallel, and a crank arm 21 like a bell crank is connected to one of said parallel links 20, with the tip of the working rod 2 connected to said crank arm 21, and the root of the support cylinder 1 connected to the base 19.In this example, the lever 13 provided at a proper position as described in the previous example is locked, to extend the working rod 2 from the support cylinder 1 to raise the bedstead 1 6 in parallel against gravity. The style and mechanism for lifting the platform 1 5 can be composed by any other way. If the platform 1 5 is lifted in this way, the load is applied through the lifting mechanism to the working rod 2, acting to shorten said working rod 2 into the support cylinder 1. However, the working rod 2 is locked by the locking piece 7 according to the principle of inclination lock, to prevent the working rod 2 from being shortened, thereby supporting said load.

And by rotating the lever 13, as mentioned above, the locking piece 7 is pivotally rotated to be erected against the resilience of the locking spring 8, allowing the working rod 2 to be shortened into the support cylinder 1, and in this state, the platform 1 5 can be lowered.

When the driving device of the present invention is used to make a lifting mechanism of the platform 1 5 as mentioned above, a buffer spring means D for energizing said platform 1 5 in the direction reverse to the action of gravity is installed to prevent the sudden drop of the platform 1 5 by the load. As far as buffer spring means D provides a force of energizing the platform 1 5 in the direction reverse to the action of gravity, the structure and place of installation can be freely selected. A preferable embodiment of the buffer spring means D is illustrated.

In this embodiment, the buffer spring means D is connected in the support cylinder 1 between the support cylinder 1 and the working rod 2, to energize the working rod 2 in the direction for the working rod 2 to be moved by the driving of said driving piece 3. If the buffer spring means D is contained in the driving device in this way, the lifting mechanism as a whole can be simplified.

The buffer spring means D described above can be a general spring means such as coil spring, but if a spring means using the compressive elasticity of a gas, viz. a spring means known as gas spring is used as illustrated, said energizing force can be adjusted easily, and a desired energizing force can be given by a small-sized means as a feature of the gas spring.

As described above, since the driving device of the present invention reasonably uses the principle of inclination lock, the driving shaft 4 can be rotated in alternate directions to repeat the reciprocation of the driving piece 3, moving the working rod 2 in one direction gradually against the load. Therefore, it has a large feature that said driving shaft 4 can be rotated not only by a lever operated by a hand, but also by a foot lever.

Figs. 8A and 8B show a preferable embodiment of the lever means used for the driving device of the present invention different from that shown in Figs. 6A and 6B and Fig. 7. The structure and action are as described below. In the drawings, symbol 22 is a rotating shaft made of a pipe, etc., and at one side of the rotating shaft 22, a guide cylinder 23 is provided, with a lever 24 slidably fitted in said guide cylinder 23. Said guide cylinder 23 has a stopper 27 which brings a stopper pin 25 into resilient contact with said lever 24 by a spring 26. Said lever 24 is provided with dents 28 which can be engaged with the tip of said stopper pin 25. In the drawing, there are two dents 28 above and below but only one dent can be provided below, or more than two dents can be provided.In the drawing, there is a slope 29 on one side of each dent 28, and this is provided to enable the dent 28 to be disengaged from said tip of the stopper pin 25, by simply moving the lever 24 at more than a predetermined force. But the slope 29 can be of course provided on the tip of the stopper pin 25. Symbol 9 is a properiy shaped grip.

In this composition, the lever means of the embodiment is connected, through its rotating shaft 22, with the driving shaft 4 of the driving device of the present invention, being installed at a side of the platform 1 5 of the bed 14, etc. For use, the lever 24 can be operated with a low force, by engaging said stopper pin 25 resiliently with said dent 28 which makes the distance between the grip 30 and the rotating shaft 22 the longest.

In this position, not only a nurse, etc. but also a patient can operate the lever means. Since the lever 24 is fixed with the stopper pin 25 resiliently engaged with the lever 24, it is kept fixed unless a force of more than that predetermined by the resilience of the spring 26 is applied in the axial direction of the lever 24. Furthermore it is free from loosening and play, and also in this regard, it does not adversely affect the operation at all.

When a patient on the bed 14 gets off from the platform 15, or when a serious patient is moved from the bed 14 to any other place, or when a nurse, etc. arranges the bed 14, the lever positioned above a side of the bed 14 is disturbing. In this case, if a force of more than that predetermined by the resilience, etc. of said spring 26 is applied in the axial direction of the lever 24, the stopper pin 25 is disengaged from the dent 28 along the slope 29, and the lever 24 can be simply shortened as illustrated, to put the grip 30 below the platform. Therefore, the grip 30 is not disturbing at all even in the above mentioned case.

As described in detail above, in the present invention, for the forward movement of the driving piece 3, the working rod 2 is moved against the load of the platform 1 5, and for the backward movement of the driving piece 3, the locking piece 7 prevents the return of the working rod 2 by the load. In other words, the working rod 2 can be moved against the load intermittently and gradually in one direction by the rotation of the driving shaft 4 in alternate directions for repeating the reciprocation of the driving piece 3, by reasonable use of the principle of inclination lock.

In the above description, the working rod is arranged to be moved, being driven by the driving piece 3, in the direction of extending from the support cylinder 1, but on the contrary, the working rod 2 can be of course arranged to be driven by the driving piece 3 in the direction of shortening into the support cylinder 1. The driving device of the present invention has the foilowing various features, when applied to the lifting mechanism of the platform of a bed, for example.

(1) Since the structure is very simple and is not large-scaled, the lifting mechanism of the platform can be made very simple. (2) Compared with the driving device with internal thread engaged with external thread, the loss of manpower by frictional force is small, making the burden of manpower small. (3) Since the working rod 2 can be moved in one direction against the load by the rotation of the driving shaft 4 in alternate directions, the operation of the lever for rotating the driving shaft 4 is simple. And for example, a foot lever can be used as the lever, and in this case, the burden of manpower for lifting the platform can be reduced further. (4) If the buffer spring means D in the direction for the working rod 2 te resile against the load is connected between the working rod 2 and the support cylinder 1, to be contained in the driving device of the present invention, the sudden return of the working rod 2 by the load can be prevented, and therefore the sudden drop of the platform can be prevented without installing such a buffer spring means D or any other buffer means in any other portion of the lifting mechanism of the platform.

enabling the entire structure of the lifting mechanism to be very simplified. (5) Since precision working of internal thread, external thread, etc. is not required, manufacture is easy, and the device can be supplied at low cost.

(6) Since the device allows manpower driving without using an expensive driving source such as a geared motor, air compressor or hydraulic pump, the space below the bed, etc. can be used effectively, and the device can be supplied at very low cost also in connection with the feature (5).

Claims (10)

1. A driving device for lifting and lowering the platform of a bed or couch, such device including a support cylinder, an axially movable working rod extending into and from the cylinder, the cylinder having a driving section and a locking section at which the rod can be driven and locked, there being a movable driving piece loosely fitted in said driving section, a driving shaft provided adjacent one side of said driving piece, a driving protrusion on said driving shaft for pushing said driving piece against the action of a return spring so that the driving piece can be moved forward by said driving protrusion and backward by said return spring, and said driving piece being engageable with said rod for driving said working rod forward upon the forward movement of said driving piece, a locking piece which is fitted loosely and pivotable and a locking spring in said locking section arranged so that when said driving piece is moved backward by said return spring, said locking piece is urged by the said locking spring to engage and lock said working rod, and including means to pivot the locking piece to a position in which it does not -lock the working rod and thus allows said rod to move backward.

2. A driving device according to claim 1, wherein said locking piece is pivotally movable by a wire against the action of the locking spring, to be pivoted from its engaging and locking position.

3. A driving device according to claim 1, including a movable releasing bar between said driving protrusion and said locking piece to be engaged by said driving protrusion on movement thereof beyond the normal range of movement, said releasing bar, when so engaged and moved, pivoting the locking piece against the action of said locking spring from its engaging and locking position.

4. A driving device according to claim 3, including a curved leaf spring between the tip of said releasing bar and said locking piece with its convex side facing the releasing bar.

5. A driving device according to claim 1, 2, 3 or 4, wherein said support cylinder contains a spring means acting on the working rod in the forward direction.

6. A driving device according to claim 5, wherein said spring means is a gas spring.

7.A driving device according to any preceding claim including a lever arrangement comprising a rotatable shaft connected to said driving shaft, a guide cylinder provided at one end of said rotating shaft, a lever removably and slidabiy received in said guide cylinder, a stopper pin provided in said guide cylinder, means urging the stopper pin into contact with said lever, and detents provided on said lever to receive said stopper pin.

8. A driving device according to any preceding claim, wherein the locking piece is perpendicular to the axis of the working rod when in its nonlocking position and inclined to that orientation when in its locking position.

9. A driving device for lifting and lowering the platform of a bed or couch, such device being substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

10. A bed or couch equipped with a device according to any preceding claim.