GB2071612A - 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 working 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 piece 3 against spring 5 thus driving said working rod forward, a locking piece 7 which is fitted loosely about rod 2 and is pivotably mounted, 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 locking spring 8 to engage and lock rod 2, means to pivot locking piece 7 to a position in which it does not lock the rod 2, a moving member 11 also being provided in said locking section to move said locking piece 7 against the locking spring and into contact with a support 12 to hold the locking piece in its non- locking position, and a stopper 13 on the rod 2 for pushing said moving member 11 via a buffer spring 14 towards the support 12 whereby at the end of outward movement of the working rod the locking piece 7 is rendered ineffective automatically. <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 it 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 a displacement to said lifting member.

A known driving device for applying such displacement to a lifting member is described, for example, in US 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 valves 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 working 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 that driving piece can be moved forward by said driving protrusion and backward by said return spring, and said driving piece being engagable 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 pivotably 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 locking spring to engage and lock said working rod, means to pivot the working piece to a position in which it does not lock the working rod and thus allows said rod to move backward, a moving member also provided in said locking section to move said locking piece against the action of said locking spring and into contact with a support means and to hold the locking piece in its non-locking position, and a stopper on the working rod for pushing said moving member via a buffer spring towards the support means on forward movement of the working rod whereby in an ultimate part of the range of outward movement of the working rod and the locking piece is rendered ineffective automatically.

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 to 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.

In order that the invention may be more clearly understood, the following description is given by way of example only with reference to the accompanying drawings in which: Figs. 1 A and 1 B shows a driving device of the present invention schematically, 1 A being an illustrative front view partially cut away to show the inside as a section, and 1 B a plan view; Figs. 2A, 2B and 2C are enlarged illustrative sections to show the structure and action of part of the driving device; Figs. 3A, 3B and 3C are illustrative front views of embodiments of driving device of the present invention applied to a bed.

Symbol 1 indicates a support cylinder containing a working rod 2 extensibly, and said support cylinder 1 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 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 with one side "b" held, being inclined by the resilience of a locking spring 8, 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 at the one side "b" by a groove 9 as shown in Fig. 2C or by a protrusion 10 as shown in Figs. 2A and 2B, as far as it can be inclined with one side supported. Further in the locking section B, a moving member 11 is provided, to move said locking piece 7 against the resilience of said locking spring 8, and in addition on the moving side, a support means 12 is provided, to support said locking piece 7 in its erect position.Moreover, said working rod 2 has a stopper means 13 for pushing said moving member 11. Between said stopper means 13 and said moving member 1 there is a buffer spring 14 positioned. In this example, said moving member 11 has a spring bearing 1 5 fitted slidably, to fix the buffer spring 14 between said spring bearing 15 and the moving member 11, positioning said buffer spring 14 between said stopper means 13 and said moving member 11.

However, the spring bearing 1 5 and the buffer spring 14 can be of course provided on the side of the stopper means 13.

In the state shown in Fig. 2A and the state shown by solid lines in Fig. 2C, 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 ieftward 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 pivotally moving 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 by a proper mechanism, to be erect, 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, to be shortened into the support cylinder 1. In the example shown in Fig.

2C, the locking piece 7 is pivotally moved by a wire means W, and in Figs. 2A and 2B, the driving protrusion 6 is moved further backward beyond the stop position reached during driving, to move a releasing bar 16, thereby pivotally moving the locking piece 7. However, any other means can be freely adopted, to pivotally move the locking piece 7.

The driving device of the present invention with such composition is used, being installed in the lifting mechanism of a platform 1 8 of a bed 17.

etc. Figs. 3A and 3B show an example, in which the root of the support cylinder 1 is fitted to a bedstead 19, and the tip of the working rod 2 is connected to a lifting member 21 provided below a movable platform portion 20, whereby said driving piece 3 is reciprocated, to extend the working rod 2 from the support cylinder 1, raising the movable platform portion 20 pivotally by the lifting member 21 against gravity. In this example, the driving shaft 4 for reciprocating the driving piece 3 can be driven by a lever 22 directly fitted to the driving shaft 4, or the lever 22 can be connected to the driving shaft through a proper motion transmitting mechanism M such as a link work, with said lever 22 set at a proper position below the bed 17.Fig. 3C shows another example, in which the bedstead 19 and a base 23 are connected by parallel links 24, to allow said bedstead 1 9 to be lifted and lowered in parallel, and a crank arm 25 like a bell crank is connected to one of said parallel links 24, with the tip of the working rod 2 connected to said crank arm 25, and the root of the support cylinder 1 connected to the base 23. In this example, the lever 22 provided at a proper position as described in the previous example is reciprocated, to extend the working rod 2 from the support cylinder 1 to raise the bedstead 1 9 in parallel against gravity. The style and mechanism for lifting the platform 1 8 can be composed by any other way. If the platform 18 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.

If said locking piece 7 is pivotally moved, to be erected from its inclined state by said wire means W, etc., the lock of the working rod 2 by said locking piece 7 is released, allowing the working rod 2 to be shortened into the support cylinder 1, and allowing the platform 18 to be lowered in this state. Symbol D in the drawing is a buffer spring means connected between the support cylinder 1 and the working rod 2, resiling in the direction for the working rod 2 to be moved, being driven by said driving piece 3, viz. in the direction against the load.Said buffer spring means D causes the working rod 2 to resile against the load, preventing the working rod 2 from being quickly shortened into the support cylinder 1 , thereby easing the sudden drop of the platform 1 8. If the buffer spring means D is contained in the driving device for lifting and lowering, of the present invention, the structure of the lifting mechanism as a whole can be effectively simplified, and it can be of course provided at any other portion in the lifting mechanism. Furthermore, the buffer spring means D can be a coil spring or gas spring using the compressive elasticity of a gas, or any other kind of spring.Thus, by repeating the reciprocation of the lever 22, the working rod 2 can be gradually extended from the support cylinder 1, to lift the platform 1 8 against the load. And when the working rod 2 is extended to its extreme point, the stopper means 13 provided at said working rod 2 reaches the locking section B, to push the moving member 11 resiliently through the buffer spring 14. The moving member 11 pushes the locking piece 7, to reach the support means 12, and since the locking piece 7 is supported in its erect state by said support means 12, the working rod 2 can be shortened into the support cylinder 1 in the load direction, viz. in the direction reverse to the movement by the driving piece 3.In this state, if the driving piece 3 is being moved forward by the driving protrusion 6, the working rod 2 is driven to the end of forward movement of the driving piece 3. Therefore, though the stopper means 1 3 moves simultaneously, the movement of the stopper means 1 3 can be absorbed by the compressive deformation of the buffer spring 1 4. For this reason, the moving member 11 is not forcedly moved, with not unreasonable force applied. If the buffer spring 14 is not provided, the working rod 2 cannot be driven after the stopper means 1 3 contacts a predetermined stop position.If the driving piece 3 is yet tried to be moved forward, the driving protrusion 6 may be damaged, or the driving piece 3 may catch the working rod 2, not allowing backward movement, to cause various inconveniences. In the present invention, such inconveniences are prevented perfectly by the buffer spring 14, as a large feature that no unreasonable forces are applied at all to the mechanism. Thus, when the driving piece 3 is moved backward, the locking piece 7 is pushed by the moving member 11 against the resilience of the return spring 8, being supported in its erect state by the support means 12, and therefore the working rod 2 is not locked, causing the working rod 2 to be shortened into the support cylinder 1 by the load of the platform 1 8.If the working rod 2 is shortened, the stopper means 13, too, moves backward from the locking section B simultaneously. If the stopper means 1 3 moves backward, releasing the moving member 11 from the resilience through the buffer spring 14, the locking piece 7 is again inclined by the resilience of the locking spring 8, to lock the working rod 2.

Thus, the working rod 2 is shortened into the support cylinder 1 by a length set by the buffer spring 14, and stops. In this way, even if the reciprocation of the driving piece 3 is repeated after the working rod 2 is extended to its extreme point, the working rod 2 is extended and shortened just by a length set by the deformation of the buffer spring 14, causing no mechanical unreasonableness. In the above description, the working rod 2 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.

As described above, in the present invention, for the forward movement of the driving piece 3, the working rod 2 can be moved against the load of the platform 1 8, 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 atainst 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.

Therefore, it has the following large 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 22 for rotating the driving shaft 4 is simple.And for example, a foot lever can be used as the lever 22, 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 to 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 1 8 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.

In addition in the present invention, the moving member for moving the locking piece against the resilience of the locking spring is provided in the locking section, and the support means for supporting the locking piece in its erect state is provided on the moving side, said working rod being provided with the stopper means for pushing the moving member, with the buffer spring positioned between the stopper means and the moving member. Therefore, even if the driving piece is moved forward when the working rod is driven by the driving piece, to be extended to its extreme point, mechanical unreasonableness is absorbed by the deformation of said buffer spring

Claims (8)

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 working 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 engagable 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 pivotably 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 locking spring to engage and lock said working rod, 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, a moving member also provided in said locking section to move said locking piece against the action of said locking spring and into contact with a support means and to hold the locking piece in its non-locking position, and a stopper on the working rod for pushing said moving member via a buffer spring towards the support means on forward movement of the working rod whereby in an ultimate part of the range of outward movement of the working rod the locking piece is rendered ineffective automatically.

2. 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, pivotting said locking piece from its engaging and locking position.

3. A driving device according to claim 1, wherein said locking piece is pivotally movable by a wire to be pivoted from its engaging and locking position.

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

5. A driving device according to claim 4, wherein the spring means is a gas spring.

6. 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.

7. 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.

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