US 3742527 A
A pneumatic operated hospital bed apparatus is made substantially from materials having a high degree of electrical insulation, whereby the bed can be operated without electricity and without providing conducting surfaces. Thus, the hazards from a patient or equipment coming into contact with a conducting surface during the use of electrically operated diagnostic or therapeutic equipment is reduced. Fluid actuated cylinders for operating the bed are also utilized to reinforce portions of the plastic bed, and a pneumatic circuit is provided with a centrally located control box for operating movable portions of the bed.
Description (OCR text may contain errors)
 3,742,527 [451 July 3,1973
3,191,195 6/1965 Schlackman et 5/63 HOSPITAL BED  Inventors: Thomas W. Johnston, Winter Park;
Primary Examiner-Casmir A. Nunberg Jack M. Pi in Sanfo d, both otFla.
pp 7 r Attorney-Robert W. Duckworth and William M.
e d a m .5 s U 5 a r a P D. a w flb m w s0 h w ,t a r e D. o .w t a m y w wln 0 7 HUA e n l t n e m n. 0 l w ea2 D m mm r m... m hh nr UOM a A n: .m d a m A F N m 2 substantially from materials having a high degree of Appl. No.: 230,605
electrical insulation, whereby the bed can be operated 82 63@ NW. 9 Q A6 m0 2 06 "7 m 6n M W mh n c nr "8 e s l l WM l Ur ln 1]] 2 8 555 ders for operating the bed are also utilized to reinforce References Cited ortions of the lastic bed and a neumatic circuit is UNITED STATES PATENTS p p p provided with a centrally located control box for oper- Peterson ti g movable portions of the bed.
5/63 6 Claims, 3 Drawing Figures Harbison PAIENIEDJUL 3 Ian SHEET 1 0f 3 HOSPITAL BED BACKGROUND OF THE INVENTION The present invention relates to hospital beds and especially to hospital beds designed to avoid hazards from electrical accidents.
In the past, electricity has caused a wide variety of accidents in hospitals which varied from a mild fright to an electrocution of hospital personnel and patients as well as damage to hospital equipment. This was especially true in the past when operating room fires and explosions were being caused by static spark ignition of flammable anesthetics. This particular type of electrical hazard has diminished but serious electrical hazards previously unknown or unrecognized have become more common today because of the use of more electrical diagnosis and therapy equipment in hospitals. Because of recent developments in bio-medical instrumentation, the patient nowadays is often-wired in such a manner that he becomes a part of the electrical system, and accidents can result at any time a human being becomes a conductor of alternating current. Electrical accidents involving a hookup of a human patient with electrical equipment generate an electrical hazard when any equipment such as a floor polisher, food truck, radio or television is near an electric bed, or when near any nearby grounding point such as a radiator, metal frame, oxygen or vacuum outlet in a wall or the like. Bio-medical equipment and instrumentation such as dye injectors, electrodardiographs, monitors and the accessories used to connect them to patients such as catheters and electrodes, provide a means of bypassing the normal protective high resistance of the skin and exposing the patient to microshock, because the human heart can be induced to fibrillate by extremely small amounts of current. It thus becomes necessary to recognize and protect against currents in the range of a few millionths of one amp, inasmuchas as little as twenty millionths of one amp can fibrillate the heart and current in this range is not perceptible to touch and can be detected only with sensitive instruments. The reason for the seriousness is that human skin when dry produces a high resistance to the conduction of electricity, but the normal electrical resistance of a body when measured from one point of the skin to another will be substantially reduced when the skin, such as the hands and feet are wet so that hookups with the patient, such as with catheters, bypass the protective high resistance of the skin exposing the patient to shock from very small currents.
In the past, electrical beds and other electrical equipment had a normal leakage current which would typically run from to 2,000 microamperes, which leakage current has not normally been considered of importance, but with the new instrumentation, greater importance is'attached to the leakage current.
It is accordingly one'object of the present invention to produce a non-electric bed built of materials normally considered as insulators against electricity because of their high resistance to the flow of electrical current for reducing the possibility of sparks from static electricity, as well as flow of electricity for a bed or for the motors driving the bed.
In the past, some hospital beds have been designed to avoid the electrical hazards by either grounding the beds and by reducing the leakage currents and utilizing low wattage control circuits.
SUMMARY OF THE INVENTION The present invention relates to hospital beds directed towards reducing electrical hazards from sparks, electrical leakage currents, and the like, and has a frame made of plastic materials including a base frame for supporting the bed which base frame can ride on casters and an upper frame made of plastic for holding the mattress support portion of the bed. A plurality of fluid actuated cylinders are connected between the base frame and the upper frame for moving the upper frame relative to the base frame upon actuation of the cylinders. Cylinders are actuated by a control panel for controlling the cylinders, as desired, which control panel can be locked. The cylinders are connected between the upper bed frame and the base frame in a manner to act as bed posts for the bed to provide additional vertical support for the bed and may be mounted in a plastic frame to prevent the contact of the metal in the cylinders with other appliances. The upper bed frame has the mattress support portion attached to it which is operated by a plurality of fluid actuated cylinders controlled by the control box for moxing the head or foot portion as desired in accordance with a predetermined path of movement. A pneumatic system is used which can be operated from a central source of air pressure, thereby not requiring electrical motors to actuate the bed.
BRIEF DESCRIPTION OF THE DRAWINGS Other objects, features and advantages of this invention will be apparent from a study of the written description and the drawings, in which FIG. 1 is a perspective view of the preferred embodiment of a hospital bed in accordance with the present invention;
FIG. 2 is a perspective view of a hospital bed in accordance with FIG. 1 showing movable portions of the bed in different positions; and
FIG. 3 is a pneumatic circuit drawing disclosing the features of a pneumatic control circuit and system for the hospital bed in accordance with FIGS. 1 and 2.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, there is a perspective view of a hospital bed 8 having a headboard 9 and a footboard 10 thereon. The bed as illustrated has substantially all of its structural components made of a plastic material except for the pneumatic cylinders and drive components which will be made of metal but which will be isolated or insulated from any contact with each other or with any contact with the patient or any instrumentation placed near the bed. The bed is also actuated in accordance with this invention either pneumatically or hydraulically but without electricity being used in the near vicinity of the bed. It should accordingly be pointed out at this point that the term plastic as used in this application when referring to the plastic structural components of the bed, is taken to mean any'substance made synthetically by polymerization, with or without fillers or reinforcements, and includes any group of synthetic or natural organic materials that may be shaped or molded while soft and then hardened. These materials provide a high degree of electrical insulation and are therefore most useful in cases like the present. Typical plastics that may be used in the present application would include epoxy resins reinforced with fiberglass, or similar high strength plastics which have the necessary strength requirements for the structural members of the bed. The headboard 9 and the footboard 10 would be required to be made of a non-insulating material, such as plastic, but because of the size of these components, could also be made of wood if desired. The bed 8 includes a base frame 11 which is made of plastic or reinforced plastic as described and would typically be made in a shape to provide greater strength so as to reduce the size of the frame structural members. Frame 11 may be, for instance, made of angled or channel-shaped elongated members connected at mitred joints by gluing or molding together. The corners and other portions may be reinforced, if desired, but this is ,not illustrated in the present application.
A lower frame 11 rides on rollers or casters 7 and has at each corner a pneumatic cylinder 12 anchored in a frame having a base 13, ribs 14 and a top portion 15. The top portion 15 of the cylinder 12 frame is connected in each case to a second cylinder frame by a structural member 16 and may be glued or anchored with bolts 17 to provide the necessary strength in the vertical direction. Reinforcing brackets 18 are anchored to the top 15 of the cylinder frame and also to the base frame 11 with rivets or bolts 20. Support in this manner could also be gained by having a longitudinally extending frame member extending between cylinders parallel to the base frame 11, if desired. Plastic materials of coure have different structural strength and requirements and similar metal materials and therefore require different structural reinforcements to provide the necessary strength to different portions of the bed. Advantageously the cylinders 12 provide added strength by being incorporated as structural members in the vertically extending posts. Each cylinder 12 has a cylinder rod 21 connected to an upper bed frame 22 which may be similar to the lower bed frame 11 except by driving the cylinders 12 simultaneously drives the rods 21 to raise or lower the upper bed frame 22. This frame is similarly made of a plastic material as previously described. The frame 22 supports the mattress support or spring 23 which includes tubular frame 24 with interconnecting straps 25. The straps 25 may be made of a plastic, if desired, but would typically be made of an elastic material such as rubber strips to give additional comfort to the bed. The straps however, would have to be an electrically insulating material. The frame 24 includes a head portion 26, a foot portion 27 and an intermediate portion 28, each of the portions being interconnected. For instance, the foot portion 27 is connected to the intermediate portion 28 by pins or shafts 30 and is also connected to the frame 22 by bars 31 pinned at 32 and 33 to maintain the foot support as the bed is moved into different positions. The foot portion 27 also has a foot support bracket 34 for the patient to place his feet against when the bed is being moved to different positions. The intermediate portion of the bed 28 is connected to a bracket 35 by pin 36 and the head portion 26 is connected to the same bracket 35 by pins 37 so that each may rotate on the pin points 36 and 37. The bracket 35 also has straps 38 passing therebetween for additional support between the movable members 28 and 26. The bed 8 includes a pivoting side rail assembly 40 which may be attached to each side of the bed by sliding rods 41 into tubes 42 in a telescoping manner so that the side assemblies 40 may be easily attached and removed from the bed. The assemblies are also provided with telescoping rods 43 which allows the rail assembly to be adjusted for use with the bed in different positions such as when the foot portion 27 is raised, as illustrated in FIG. 1, therby moving the tubes 42 in relation to each other. In addition to the upright cylinders 12, foot control cylinder 44 and a head control cylinder 45 are provided for operating the bed. Foot portion 24 and head portion 26 cylinders 44 and 45 are encased in a plastic similar to the frames for cylinders 12 and has a connecting bracket 48 connected to a bracket 50 which in turn is connected to a transversely extending support member 51 in FIG. 2. The drive rod 52 is located at the opposite end of the cylinder 44 and is connected to a drive member 53 by a pinned bracket connector 54. The drive member 53 is connected to a rod 55 extending trans.- verse of the bed and being connected to a pair of brackets 56 connected to the intermediate portion 28 of the bed or mattress support 23. Thus extending the cylinder rod 52 of the cylinder 44 will drive the intermediate portion 28 of the mattress support 23 into a raised position rotated on the pin 36 and will force the foot portion 23 on the rods 31 to be raised in a predetermined manner. Similarly, the head drive unit of cylinder 45 is pinned to a bracket 60 at one end and has an extending or retracting rod 61 at the opposite end pinned at 62 to a drive rod 63 which in turn is connected to a rod 64 which is connected to bracket 65 which are fixedly attached to the head frame 26 so that driving of the cylinder 45 will drive the head portion of the bed 26 in a pivoting position pivoting on points 37 of the brackets 35.
A pneumatic control box drives the pneumatic cylinders 12 and 44 and 45 to operate the bed in accordance with the actuation of the controls in the control unit 70 as illustrated. A detent pneumatic selector control 71 operates the head of the bed or cylinder 45 while detent pneumatic selector control 72 controls the foot portion of the bed. A switch 76 is a selector control having three positions for controlling the pneumatic cylinders 12 for an up-down and an off position so as the bed could be located at any height as desired by the patient or the doctor. A key-lock device 73 is provided for locking the pneumatic system at any position desired by turning the key to the locking position and removing the key 69. The controls are then rendered inoperative until reinsertion of the key 69 and turning the key-lock device 73 to the on position. This may be done by the attending physician or nurse where the patient is a case where moving of the bed once positioned would be detrimental or undesirable. The speed with which the portions of the bed may be raised or lowered may be controlled from slow to fast and in increments therebetween by a needle-valve with a dial speed selector 74 for the foot portion of the bed'and by a needle valve with a dial speed selector 75 for the head portion of the bed. More detailed operation of the pneumatic system is illustrated in FIG. 3.
It should of course by clear that the pneumatic sys tem is utilized because many hospital rooms have or can be provided with air under pressure for driving the pneumatic system without having an electrical drive unit unit nearby and thus avoiding the potential electrical hazards from the electrical motor drive or the like.
Referring now specifically to FIG. 3, the controls from the control box 70 can be seen separated from the control box and interconnected with the pneumatic circuitry and showing the line connections between control box and the cylinders 12, 44 and 45. The key-lock 73 can be seen for locking the controls along with the bed selector control 76 for raising the bed up, down or locking in any predetermined position. The foot control selector 72 for controlling the foot portion of the bed and the head selector control 71 for controlling the head portion of the bed through cylinder 45. That is, control 76 controls the cylinders 12, 72 controls the cylinder 44 and 71 controls the cylinder 45. Controls 74 and 75 control the speeds for operating the cylinders. For clarity, this view also illustrates a portion of the bed itself including the lower framework 11, bracing support brackets 18 along with the rivets 20 and the wheels or casters 7 and the frame for holding the cylinders 12 including the bottom portion 13, ribs 14, top portion 15 and portions of the support members 16. Also illustrated are portions of the upper frame 22 along with brackets 60 connected to the cylinder 45 and bracket 50 connecting to cylinder 44. The air enters the system at 80 from an air pressure source which may operate at 80 PSI and may be operated from the in-hospital compressed air system or the bed may be provided with its own air compressor unit and reservoir, as desired. The air is passed through a combined unit having a filter 81, an air pressure regulator 82 and a lubricator 83 prior to entering the control valve box 84 which may be a full wave double pressure piloted control valve for operating the system and is a commercially available unit. The control valve is connected to each of the pneumatic cylinders 12, 44 and 45 and is also connected to each of the controls 71 to 76 for controlling the application of the air pressure from the source 80 to predetermined cylinders and for locking each cylinder at a predetermined location. The entire pneumatic system is shown connected with lines 85 which may be plastic such as polyvinyl tubing and in the system as illustrated can be A inch outside diameter plastic tubing to prevent conduction of electricity between different areas of the bed.
It should be clear at this point that a safety hospital bed has been provided, especially adapted for the protection against the electrical hazards commonly found in hospital beds such as the patientstouching conducting portions while connected to various electrical instrumentation, or by resulting sparks, resulting from the static electricity. It should also be clear, however, that other embodiments are contemplated as being within the scope of the invention. For instance, while a pneumatic system has been spelled out because of the desirability of being able to connect to hospital air sources, it is also contemplated that a hydraulic type system would be equally effective except for the liklihood of locating a hydraulic pump having an electric motor near the bed.
Accordingly, this invention is not to be construed as limited to the particular forms disclosed herein since these are to be regarded as illustrative rather than restrictive.
1. A fluid actuated electrically insulated hospital bed comprising in combination:
a. a plastic base frame for a hospital bed;
b. a plastic upper bed frame having mattress supports connected thereto;
a plurality of fluid actuated cylinders bedposts connecting said frame and said upper bed frame for moving said upper bed relative to said base frame when said cylinders are actuated to drive the cylinder rods;
control means for controlling the operation of said cylinders;
. each said bedpost cylinder being mounted in plastic frames; and
f. said bed having an electrically insulated headboard connected to said upper bed frame and an electrically insulated footboard connected to said bed frame, whereby electrical hazards are reduced in the hospital bed.
2. The bed in accordance with claim 1 in which said fluid actuated cylinders are pneumatic cylinders.
3. The bed in accordance with claim 2 in which said pneumatic cylinders are controlled from a central control panel.
4. The bed in accordance with claim 3 having pneumatic cylinders connected to said upper bed frame and said mattress supports for moving said mattress supports.
5. The bed in accordance with claim 4 in which said central control panel has a lock means for locking the controls to said pneumatic cylinders.
6. The bed in accordance with claim 5 in which said base frame includes frame members connecting said bedposts cylinders between the base of said cylinders and also frame members connecting said cylinders at the head thereof.