US2592166A - Safety bed - Google Patents

Description

April 8, 1952 c. c. MOLEAN ET AL 2,592,166

SAFETY BED Filed 001;. 17, 1947 2 SHEETS-SHEET 1 mmmwm COL/N C MCLEAW SQNDER H. Dav/5 FITTORNE YS April 8, 1952 c. c. MCLEAN ET AL 2,592,166

SAFETY BED Filed Oct. 17, 1947 V 2 SHEETSSHEET 2 Cou/v C McLEm/ 50 /0556. DfiV/S 2! 23mm, uym' 060mm 4' Jam/mu f 7 if ATTORNEYS Patented Apr. 8, 1952 SAFETY BED Colin 0. McLean and Sander A. Davis, Chicago,

111., assign ors to Hospital Furniture, Inc., Ohicago, 111., a corporation of Illinoisv Application October 17, 1947, Serial No. 780,486

3 Claims. (Cl. -63) This invention relates to a bed and more par ticularly to a bed which may be adjusted at any height from the normal low level of a home bed to the high position of hospital beds.

The top of the mattress of the usual home bed is about 24 inches above the floor. The height of a hospital bed, on the other hand, is standardized at a height of 33 inches to raise the patient to a convenient height for examination or treatment. It is not desirable to maintain a bed at the higher level because of the likelihood of a serious injury resulting from a fall. A bed which may be adjusted from one level to the other is highly desirable.

Beds which may be adjusted to a number of different heights have heretofore relied on a series of mechanical connections spaced at intervals along the posts of a bed. The connections usually have been either of the familiar bayonet type or have consisted of a series of holes in the bed posts for the reception of a pin connected to the frame of the bed. In order to change the level of beds of the type described, it is obviously necessary that the occupant of the bed be moved therefrom while the level is being changed.

In order to facilitate the adjustments of the level of the bed, some prior structures have a rack and pinion gear mechanism with the rack secured to the posts of the bed. Here, again, the prior structures have made it necessary to adjust the height of one end of the bed at a time thereby making it necessary for the occupant to be moved from the bed while it is being adjusted to the desired position. Moreover, the prior structures have relied upon a ratchet to hold the bed in position. Unless great care is taken in the setting of the ratchet, there is a strong possibility that the ratchet will slip when weight is first put on the bed.

It is an object of this invention to provide a bed which may be adjusted at any desired level between the normal low level of a home bed and the high level of a hospital bed.

Another object of this invention is to provide a bed the height of which may be adjusted while an invalid is in the bed. j

Still another object of this invention is to provide a safety bed which may be of attractive appearance and in which the mechanism for "adjusting the level of the bed is concealed and guarded.

A further object of this inventionis a bed which may be adjusted at any desired height and which will lock in place without danger of slipping.

With these and other objects in mind which will become apparent in the following detailed description of the invention, this invention resides in a bed having legs slidable within the corner posts. A rack secured to each of the legs is engaged by pinion gears in a fixed position relative to, and rotatably connected with, the corner posts for moving the legs relative to the corner posts. A worm gear mechanism is mechanically linked with the pinions to move all legs simultaneously and hold the bed at the desired level.

In the drawings:

Figure l is a perspective view of a bed constructed according to this invention.

Figure 2 is a horizontal sectional view illustrating the mechanism provided for extending all of the legs of the bed simultaneously. 7

Figure 3 is a vertical sectional View of the mechanism taken along section line 3- 3- of Figure 2. V

Figure 4 is a vertical sectional view along the line 4-4 in Figure 2 of the leg and corner post structure of the bed.

Figure 5 is a schematic diagram of the electrical connections for operating the motor for raising and lowering the bed. 7

Referring to Figure 1, the bed, indicated generally by I, is illustrated having a headboard 2 and a footlooard 3.. Attached to each end of the headboard and foot'board are corner posts 4 into which legs 5 extend. A frame, indicated generally by 6, is attached to the corner posts for the support of the springs and mattress of the bed. Frame 6 consists of side rails 1 extending between the head and foot boards 2 and 3 at the ends of the bed. In some instances it may be desirable to extend rails, not shown in the drawing, parallel to the head and foot boards rather than use the head and foot boards as" part of the frame of the bed. The terms headboard" and footboard" are used to designate the structure at the ends of the bed joining the corner posts and are not limited to the details of the structure illustrated.

1 Corner posts 4 have a long cavity 8 in their lower end in which the legs 5 of the bed fit snugly but slidably. An opening 9 is provided in the walls of cavity 8 for passage of the mechanical linkage raising and lowering the bed. The upper end of corner post 4 is drilled to iorm a well 10 in which racks, not shown, for the supportof equipment for blood transfusions or glucose injections, or exercisingapparatus, may be anchored. Each well is covered with a cap [I hinged at l2 to the upper end of the corner post.- v

The legs 5 are of any conventional type equipped with a caster [3 at theirlower end and fit in a telescoping manner in the cavity 8 of-tl-ie corner post 4. A rack i4 is secured to a side or the legs,

near their upper end and in alignment with the opening 9' in the corner post of the bed. It is preferred that the legs 5 -fit within the corner post [rather than have the corner post 4' slide .rotation of the spindles and In the form of the iifiention illustrated in the drawings, the frame supporting the springs and mattress consists of side rails l and head and foot boards 2 and 3. The frame serves as a support for pinion gears l6 which engage the rack l4, as hereinafter described, and the mechanism for driving the pinion gears. The frame is securely fixed to either the corner post or headboard and footboard of the bed and remains in fixed relation to the corner posts as the leg slides within the corner post. As illustrated in Figure 2, an electric motor I! is secured to base l8 attached to. the frame 6 of the bed.

The motor I1 is thoroughly insulated from the bed and is preferably completely enclosed. In the drawings the shaft 19 of the motor is joined by means of couplings 20 and 2! directly to a shaft 22 extending the full length of the bed. In some instances it may be desirable to install a speed reducer between the shaft l9 of the motor and the shaft 22 to reduce the rate of rotation of shaft 22 and, as a result, the rate of movement of the bed.

Shaft 22, which extends substantially the full length of the bed, is supported at its ends by pillow blocks 23 and 24. By locating motor I! near the middle of the bed, the bearings of the motor are made to serve as support for the shaft 22. Worm gears 25 and 26 are secured to shaft 22 near each end thereof for transmitting power from the shaft;

Extending perpendicularly to shaft 22 at each end of the bed are spindles 21 and 28. The spindles 21 and 28 are rotatably supported below the shaft 22 by pillow blocks 29 attached to the corner posts 4 of the bed. Keyed to the spindles 21 and 28 are worm wheels 30 and 3| which engage the worm gears 25 and 26, respectively,'to rotate the spindles. The speed reduction of the worm gear and worm wheel assembly is employed to adjust the rate of elevation of the bed to the desired speed. By proper design of the worm gear and worm wheel linkage, the necessity for a speed reducer between the shaft of the motor -and shaft 22 is obviated. The pinion gears l6 mentioned in connection with rack l4 are keyed to the spindles 21 and 28 near their ends. The

pinion gears l6 extend through the openings 9 to engage the racks l4 attached to the legs of the bed.

The worm gear and worm wheel mechanism for rotating the pinion gears [6 provides a means for locking the bed in positionat the height it occupies when the motor is stopped. The weight of the bed and the person in the bed urges the pinion gears l6 downward and tends to turn the pinion gears l6 backwards on the spindles when the motor is stopped. The worm wheels 30 and 3| engage the worm gears 25 and 26 to prevent pinion gears l6 and hold the bed firmly in place.

It will be noticed that all of the pinion gears I6 are driven simultaneously to maintain the bed in a horizontal condition as it is being raised or lowered. The bed may be raised orlowered ,with perfect safety while occupied;

Referring to Figure 5, a limit switch for the control of the operation of the motor is illustrated schematically. Shaft 22 is threaded at .32 for the reception of a nut 33. -An arm 34 i s complete the circuit to the motor I! through lines 38 and 39.

In the electrical circuit through the motor I! is a reversible switch 40 indicated by a conventional electrical symbol. Switch 40 is preferably located on the headboard of the bed as indicated in Figure 1. Reversible switch 40 is normally in an open position preventing current from flowing to the motor I1. It is necessary that switch 40 be held in the closed position to operate the motor. Power for operating the motor is received through lines 4| and 42 which are connected to a suitable outlet, not shown.

If the bed is at the lower position of a normal home bed and it is desired to raise it to the elevated position of a hospital'bed, it is merely necessary to depress the proper button of reversible switch 40. The closed switch allows the electrical current to flow to the motor which then rotates shaft 22. Shaft 22 in turn drives spindles 21 and 28 and the pinion gear 16 simultaneously. Pinion gears l6 engage the racks l4 in each of the legs of the bed and cause the legs to move within the cavity 8 of the corner post 4. It will be noted that the spindles 21 and 28, and, accordingly, pinion gears l 6 are attached securely to the frame of the bed which i turn is rigidly connected with the corner post 4. As a result, spindle I6 will remain in a fixed position relative to the corner post 4 and its rotation will cause the rack l4 and legs 5 to move relative to the corner post.

As rotation of shaft 22 continues, the nut 33 will travel along the threaded portion 32 of the shaft until arm 34 engages the closed switches 31, for example, and opens the electrical circuit. The motor I! then stops and the bed is held in position by the worm wheel and worm gear arrangement.

It will be noted that ordinarily both switches 36 and 31 are closed and that only one of the switches will be open at one time. The traveling nut 33 and arm 34 arrangement will accordingly always condition the electrical circuit for the movement of the bed in a direction opposite its last movement. Of course, if the bed is not elevated sufficiently to trip switch 31, both switches 36 and 31 will be closed and the bed may be either raised or lowered by depressing the proper button in switch 40. i

In some instances it is desirable that the shaft 22 be extended past pillow block 24 and pass through the footboard 3 for detachable connection with a crank 43. The bed may then be operated when a suitable source of electric power is not available.

The bed herein described may be readily raised or lowered to the desired height while the bed is occupied. The mechanism of this invention alters the effective length of the leg of the bed simultaneously to maintain the bed in a horizontal position as its height is being changed. Moreover, the mechanism for altering the effective length of the legs is enclosed and concealed to prevent entanglement with the bed clothes and to provide a bed of pleasing appearance.

A bed constructedaccording -to this invention has been described herein with reference to a particular structure. It is to be understood that the concept of this invention is not limited to the details of the structure described, but is defined by the appended claims.

We claim:

1. A hospital safety bed comprising a mattress supporting frame, tubular corner posts secured-to the corners of the mattress supportingframe; a leg slidable in each of the corner posts, a 'r'aelggon each leg, a motor secured to the frame, a shaft driven by the motor, said shaft extending the length of the bed and rotatably supported by the frame, a spindle rotatably supported at each end of the bed, a pinion gear on each end of the spindles, a worm gear on each end of the shaft engaging a worm wheel on the spindles, an opening in each of the corner posts permitting-the pinion gears to engage the racks On the.., leg s of the bed, switch means for closing a circuit to operate the motor to raise and lower the mattress supporting frame, said shaft having a threaded section along its length, and limiting means travelling on the threaded section adapted to open the switch means to limit movement of .the bed, said limiting means stopping movement of the bed at the treatment level when the bed is moving upward and the normal bed height when the bed is moving downward.

2. A hospital safety bed adjustable to an upper treatment position and a lower safety position comprising a single mattress supporting frame, corner posts secured to the frame, a leg slidable within each of the corner posts, means for 'mov ing all of the legs relatively to the corner posts simultaneously, said means including an electric motor mounted on the frame adapted to move therewith, a shaft rotatably supported from the frame and driven by said motor, a rack secured to each of the legs, pinion gears rotatably suD- ported from the frame engaging the racks, worm gears on the shaft adapted to drive the pinion gears and move the legs relatively to the corner posts, said motor adapted to turn in either direction to move the legs into and out of the corner posts, and limit switches operated by said shaft adapted to break the circuit to the motor to stop the movement of the bed at the treatment position as the bed moves upward and at the safety position as the bed mbves downward.

3. A hospital safety bed adjustable to an upper treatment position and a lower safety position comprising a single mattress supporting frame, corner posts secured to the frame, a leg slidable within each of the corner posts, means for moving all of the legs relatively to the corner posts simultaneously, said means including an electric motor mounted on the frame, a rack mounted on each of the legs, pinion gears mounted on the frame and engaging the racks'to move the legs relative to the corner posts, and means driven by the motor for turning thejpinion gears to move the legs in the corner posts simultaneously, said motor adapted to turn in either direction to move the legs into and out of the corner posts, and limit switches operated bythe motor adapted to break the circuit to the motor to stop the movement of the bed at the treatment position as the bed moves upward and at the safety position as the bed moves downward.

COLIN c. McLEAN. SANDER A; gmwrs.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,228,434 Hedberg June 5, 1917 1,265,257 Schellinger May 7, 1918 1,366,517 Brown June 25. 1921 2,522,759 Lindquist Sept. 19, 1950 2,523,076 Sweetland Sept. 19, 1950

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