US 3492679 A
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1970 w. D. DREW 3,492,67
TRENDELENBURG CONTROL MECHANISM Filed Feb. 25, 1968 I 5 Sheets-Sheet 1 fi/ezzz or z'f/z'am pfew Feb. 3 1970 wqb. DREW 3,492,679
TRENDELENBURG CONTROL MECHANISM Filed Feb. 25. 1968 3 Sheets-Sheet 2 2 #ezz 2501" Feb. 3, 1970 w. o; DREW 3,492,679
TRENDELENBURG CONTROL-MECHANISM v Filed Feb. 25. 1968 I 3 Sheets-Sheet 5 United States Patent O 3 492 679 TRENDELENBURG coNrRoL MECHANISM William D. Drew, Batesville, Ind., assignor to Hill-Rom Company, Inc., Batesville, Ind., a corporation of Indiana Filed Feb. 23, 1968, Ser. No. 707,616 Int. Cl. A61g 7/00; A47e 22/00 US. Cl. -68 7 Claims ABSTRACT OF THE DISCLOSURE CROSS REFERENCE This invention is an improvement of the Trendelenburg position limit control contained in the Hillenbrand et al. Patent 3,237,212 issued Mar. 1, 1966.
BACKGROUND OF THE INVENTION This invention relates to hospital beds, more particularly it relates to electrically driven hospital beds. In these beds, a limit position control stops the motor when the head section of the spring frames of the bed reaches a horizontal position. In the treatment of patients it is often necessary to lower the head section of the spring frame of the bed from horizontal into the Trendelenburg position. To do this it is necessary to alter the limit position control to permit continued operation of the motor when the horizontal position of the head section of the spring frame is reached.
DESCRIPTION OF THE PRIOR ART The Hillenbrand et a1. Patent 3,237,212 discloses an electrically driven hospital bed having a lower frame supported upon the floor. An upper frame is mounted upon said lower frame for movement longitudinally of said frames. The spring frame is supported on said upper frame. A cross tube pivotally mounted upon the head section of the spring frame engages a levelizer mounted upon the upper frame when the head section is in horizontal position. The motor of the bed is controlled by a rod that is rotated from a neutral position to start the motor. A cam carried upon the upper frame is moved into engagement with a pin on said rod to rotate the rod back to its neutral position to stop the motor when the head section reaches horizontal position.
When the head section of the spring frame is to be placed in Trendelenburg position, the cross bar on the head section is rotated on its pivots into position inclined with respect to the head section and held in this position against the tension of a spring which normally holds it at right angles thereto. A lever on the upper frame is operated to alter the limit position cam to permit the motor to operate beyond the normal limit position. The motor is then started and the head section thereby lowered until the limit cam stops it when the head section reaches Trendelenburg position. To restore the bed to normal after the head section is raised slightly, the spring pulls the cross tube back into position at right angles to the head section and the lever is restored to normal to return the limit position cam to normal.
SUMMARY OF THE INVENTION The present invention has for its principal object the provision of an improved mechanism for controlling the lowering the head section of the spring frame of an electric motor driven hospital bed into Trendelenburg position, which mechanism returns to normal automatically as the head section is returned to horizontal position.
The machanism consists of a cross tube fixed upon the head section of the spring frame and depending therefrom at right angles thereto; a levelizer pivotally mounted upon the upper frame of the bed and maintained in vertical position by the engagement of a crank arm on the levelizer with a spool in a preset mechanism. The levelizer is moved into position inclined to vertical by axial movement of the spool; a tie rod connects the crank arm to the cam plate to alter the limit position of the head section operating means. The mechanism thus preset remains preset without any part of the mechanism being held manually in altered position and is restored to normal automatically by restoration of the head section of the spring frame to horiztontal.
The invention will be understood best from the detailed description and claims which follow reference being had to the accompanying drawings in 'which a preferred embodiment of the invention is shown by way of example and on which:
FIGURE 1 is a fragmentary side elevational view of a hospital bed containing the mechanism of the invention;
FIGURE 2 is a fragmentary plan View showing the limit the position cam plate of the bed;
FIGURE 3 is a plan view showing the levelizer and preset mechanism;
FIGURE 4 is a fragmentary side elevational cross sectional view along the line 4-4 of FIGURE 3' looking in the direction of the arrows, drawn to an enlarged scale and showing the mechanism in preset position; and
FIGURE 5 is an elevational view of the present spool in preset position.
Referring noW to the drawings in more detail, from FIGURE 1 it will be seen that the bed of the type to which the instant invention applies contains a lower frame 10 upon which an upper frame 11 is mounted for movements longitudinally of the lower frame. Attached to the upper frame is a spring frame containing a seat section 12 to which a head section 13 is pivotally attached.
Fixed upon the head section 13 is a cross tube 14 that extends downwardly from the frame of the head section at right angles thereto. Pivotally mounted upon the upper frame is a levelizer 15 which the cross tube 14 engages when the head section 13 of the spring frame is in horizontal position.
As will be seen best in FIGURES 3 and 4, the levelizer is in the general shape of an inverted U the vertical legs 16 of which are attached to a cross tube 17 in any preferred manner such as by welding. Rivets 18 project through the side rails of the upper frame 11 and into the cross tube 17 to pivotally mount the levelizer upon the frame 11. The rivets are secured in the cross tube by suitable means such as drive pins 19.
Journaled in the side rails of upper frame 11 with its axis parallel to the axis of tube 17 is a preset rod 20 that is equipped with knobs 21 located at its outer ends. Fixed upon the preset rod is a preset spool 22 best seen in FIGURE 5. The spool consists of a central cylinder 23 the diameter of which is but slightly larger than the diameter of the rod 20. Rising from each end of the section 23 are conical cams 24. Located at each end of the spool 22 is a larger diameter cylindrical end section each of which is separated from the cam 24 by a radial shoulder 26. Surrounding the preset rod 20, and abutted against the side rails of frame 11 and a suitable collar suitably fixed upon the rod 20, are springs 27.
Fixed upon the levelizer tube 17 and extending across the preset rod 20 is a crank arm 30 which when the preset rod is in normal position engages the small diameter cylinder 23 of the preset spool. With the crank arm in this position, the levelizer is disposed vertically and is engaged by the cross tube 14, when the head section of the spring frame reaches its horizontal position. Connected to the crank arm 30 is a tie rod 31 the other end of which is connected to the limit plate 32 that is slidably mounted beneath the section 12 of the spring frame and has a depending cam 32. Attached to the end of the tie rod 31 that is projected through an opening in the crank arm 30 is a spring 33, the other end of which is connected to a cross member 34 of the upper frame 11.
As is fully explained in the above mentioned patent a control rod 35 carries a pin 36 which is disposed horizontally when the control rod 35 is in its neutral position. When it is desired to lower the head section 13 of the spring frame and to simultaneously move the upper frame 11 to the right, as seen in FIGURES 1 and 2, control rod 35 is rotated to position the pin 36 at an upward angle with respect to horizontal as shown at 36. As the upper frame 11 moves to the right, the cam 32 engages the pin and moves it from the inclined position 36' down into horizontal position and thereby bring the head section 13 of the spring frame to rest with the cross tube 14 engaging the levelizer 15.
When it is desired to move the head section of the spring frame into Trendelenburg position the motor of the bed is operated to raise the head section slightly so as to remove pressure on the levelizer 15 by moving the cross tube 14 a short distance thereabove. The preset rod 20 is then moved axially by pushing one of the knobs 21 inwardly towards the frame 11. It will be noted that the preset rod can be moved in either direction and as shown in FIGURE it has been moved to the right to move the preset spool 22 from the position in which it is shown in dotted lines into position shown in full lines.
This movement of the preset spool, through the engagement of the crank arm 30 with the cam 24, raises the crank cam and thereby moves the levelizer out of vertical position into position inclined with respect to vertical, as shown in FIGURE 4. This movement increases the tension of spring 33 and the crank arm 30 is held against the end cylinder 25 and the preset spool is held against the tension of the operated one of its encircling springs 27 by the engagement of the crank arm with the radial shoulder 26. Upward movement of the crank arm 30 moves tie rod 31 to the left as seen in FIGURE 2 thereby sliding the limit plate 32 so as to require greater movement of the frame 11 before the cam 32 engages the pin 36. The mechanism is thus preset to permit lowering the head section 13 of the spring frame into Trendelenburg position and is retained in this preset position in the foregoing manner thus leaving the attendants hand free to control the movement of the bed and to care for the patient should special attention he required.
Downward movement of the head section 13 causes the cross tube 14 to slide down the edge of the vertical arm 16 of the levelizer 15. This raises the crank arm 30 which in turn further slides the limit plate 32 so as to permit lowering the head section into Trendelenburg position. Downward movement of the head section can continue until cross tube 14 engages crank arm 30, although this extreme position will seldom be used.
Elevation of the crank arm 30 by the rotation of the levelizer around its pivot disengages the crank arm from the radial shoulder 26 on the preset spool and the spring 27 compressed by the longitudinal movement of the preset rod 20 restores that rod and spool to its normal position in which the small diameter central cylinder 23 is aligned with the crank arm 30.
When it is desired to restore the head section 13 of.
the spring frame to its normal horizontal position, control rod 35 is rotated in the opposite direction and the motor of the bed operated to raise the head section and simultaneously move the upper frame 11 towards the head end of the bed. As the cross tube 14 moves upwardly along the levelizer, spring 33 pulls the levelizer back into its vertical position and tie rod 31 restores cam 32 to its normal position. When the levelizer is in vertical position, crank arm 30 is reregistered with the small diameter cylinder 23 thus bringing the mechanism back to its normal position.
From the foregoing, it will be apparent that the preset control mechanism of the present invention, when moved to a preset position preparatory to lowering the head section of the bed into Trendelenburg position, retains itself in preset position leaving the hands of the nurse or attendant free to operate the bed and administer to the patient should necessity arise. The mechanism is of simple construction and capable of operating satisfactorily over a long period of time with little or no maintenance.
Having thus complied with the statutes and shown and described a preferred embodiment of my invention, I have done so by way of example only as there are many adaptations and modifications which can be made by one skilled in the art within the teachings of the invention. What I consider new and desire to have protected by Letters Patent is pointed out in the appended claims I claim:
1. In a motor driven hospital bed that has a spring frame carried upon an upper frame that is supported upon and movable with respect to a lower frame as the head section of the spring frame is raised from and lowered into horizontal position, and in which a control rod is journaled in the lower frame for rotation around its axis and carries a pin disposed horizontally when the rod is in neutral position and inclined upwardly with respect to horizontal when the rod is in operated position, and in which a limit position cam slidably mounted upon said upper frame engages said pin and lowers it from operated to neutral position as the head section of the spring frame moves into horizontal position, an improved mechanism for enabling the head section of the spring frame to be lowered from horizontal into Trendelenburg position, said mechanism comprising:
(a) levelizing means including a cross tube fixed upon the head section of the spring frame and disposed at right angles thereto; and a levelizer pivotally mounted on the upper frame and normally disposed vertically and in engagement with said cross tube to hold the head section in horizontal position;
(b) preset means for altering said levelizing means preparatory to moving the head section downwardly;
(c) and means operated by said preset means for sliding the limit position cam to alter the point of engagement of the plate with said pin on the control rod.
2. Mechanism as specified in claim 1 in which the preset means includes a preset rod journaled in the upper frame with its axis parallel to the pivotal axis of the levelizer; a preset cam spool fixed upon said rod; and a crank arm fixed upon the levelizer and engaging said spool.
3. Mechanism as specified in claim 2 in which the spool includes a central cylinder engaged by said crank arm to hold the levelizer in vertical position, conical cams one at each end of said central cylinder for raising said crank arm as the spool is moved axially; a larger diameter cylinder at each end of the spool into engagement with which the crank arm is moved by axial movement of the spool; and a radial shoulder, adjacent the inner end of each of said end cylinders, engaged by the crank arm, holds the spool in preset position.
4. Mechanism as specified in claim 3 in which movement of said crank arm from the central to the end cylinder of the spool rotates said levelizer on its pivots to register the cross tube with the edge of the levelizer, and
in which downward movement of the cross tube cams the levelizer into a position more inclined from vertical and raises the crank arm oil of said end cylinder and out of engagement with said shoulder thereby releasing the spool.
5. Mechanism as specified in claim 4 in which spring means encircling the preset rod restores the spool to its normal position with the central cylinder aligned with said crank arm.
6. Mechanism as specified in claim 5 in which a tie rod connected between the crank arm and cam plate slides the cam plate as the crank arm moves upwardly to require movement of the cam plate through the normal limit position before engaging the control rod pin to move it from operated to neutral position.
7. Mechanism as specified in claim 6 in which a spring UNITED STATES PATENTS 3,231,904 2/1966 Shulkin 5-69 X 3,237,212 3/1966 Hillenbrand et al 568 3,398,411 8/1968 Douglass 569 X 3,402,408 9/1968 Hutt 568 CASMIR A. NUNBERG, Primary Examiner U.S. C1. X.R. 5-66