Patent Description:
The use of release mechanisms in drives for patient support apparatuses such hospital beds and stretchers is known as a way to quickly lower a frame section using gravity and/or patient weight. The activation of the release mechanism is typically manual and transfers mechanical movement between an activation handle and the release mechanism to make the release available even when power is not available. In some instances, the release mechanism mechanically releases portions of the drive to allow the drive to be back driven to a lowered position. In other cases, the release mechanism may vent or dump hydraulic fluid or air from a cylinder to allow the cylinder to be lowered.

However, due to misuse, the structures used may be damaged such as by overuse when housekeeping uses the release mechanism to quickly lower the frame during a cleaning cycle, or when visitors activate the activation handle out of curiosity or boredom, cycling the structure more often than appropriate. Still further, the activation handle may be damaged by caregivers who activate the release mechanism in an emergency situation, applying excessive force in an attempt to urge the frame to move quicker. This overuse can result in a loss of adjustment and a freedom of movement that is problematic.

<CIT> discloses a bed comprising a fixed width deck section, a wing movably coupled to the fixed width section, a leadscrew having a rotational axis, a leadscrew driver coupled to the leadscrew for rotating the leadscrew about its axis, and a release unit. The release unit is coupled to the wing and configured to move between a) an engaged position in which the release unit engages the leadscrew and moves there along as the leadscrew rotates about the rotational axis, thereby causing the wing to translate relative to the fixed width section; and b) a disengaged position in which the release unit is disengaged from the leadscrew.

<CIT> discloses a manual CPR release for a hospital bed that mechanically releases the head section from the dead drive motor to quickly lower ahead section to a flat position. When the head section reaches its lower limit, a switch is actuated which produces a command signal initiating the operation of both the head and knee drive motors. The knee drive motor lowers the thigh and foot sections to their flat positions and brings them into a coplanar position with the head section. Operating the head drive motor moves the head drive, nut back into mechanical engagement with the head section.

<CIT> discloses a quick release for the backrest of hospital stretchers. The conventional threaded crank actuator carries a mating threaded block and a sliding block, the sliding block being connected to the headrest. Manually operated hook means permits disengagement between the blocks to free the backrest. Inadvertent disengagement preventing safety means, and re engagement means are also provided.

<CIT> discloses a hospital bed consisting of an intermediate fixed portion and angular raisable back portion. The hospital bed further comprises safety sides comprising an upper and a lower section. The lower section comprises a pair of spaced L-shaped arms joined at their upper ends by an integral cross member. A leaf spring urges a latch toward a locking position to lock the upper and lower sections of the safety side together.

The present disclosure includes one or more of the following features, alone or in any combination.

According to a first aspect of the present disclosure there is provided a patient support apparatus comprising a first frame; a second frame pivotably coupled to the first frame; a drive secured to the first frame and the second frame, the drive operable to move the second frame relative to the first frame, wherein the drive includes a release mechanism which is operable to disengage a portion of the drive to allow the second frame member to move freely relative to the first frame; and an activation assembly for activating the release mechanism of the drive, the activation assembly including: a pivot pin configured to engage with the second frame; a bracket positioned on the pivot pin and pivotable about the pivot pin relative to the second frame, the bracket including a lever arm configured to engage a motion transfer link coupled to the release mechanism such movement of the lever arm is transferred through the transfer link to the release mechanism; a bias member is engaged with the bracket to move with the bracket and to engage a pair of spaced apart motion limiters secured to the second frame, the bias member including a body and a pair of arms positioned on opposite sides of the body, the arms each configured to engage a respective motion limiter and maintain engagement with both motion limiters when the activation assembly is in a neutral state; and a handle coupled to the bias member, the movement of the handle resisted by the bias member and transferred from the handle to the lever arm.

In some embodiments of the first aspect, a first one of the pair of arms may deflect when the handle is moved in a first direction and a second of the pair of arms may disengage the respective motion limiter.

In some embodiments of the first aspect, the first one of the pair of arms may urge the activation assembly to the neutral position when the handle is released.

In some embodiments of the first aspect, the activation assembly may further comprise a coupler cam that is positioned on the pivot pin and pivotable about the pivot pin. When present, the coupler cam may be secured to the bracket to move with the bracket about the pivot pin. The coupler cam may include a cam surface configured to engage an activation arm of a switch assembly and activate the switch when the activation assembly is moved from the neutral position to an activated position.

In some embodiments of the first aspect, the coupler cam may include a pin extending therefrom and the bracket may include a hole in a surface of the bracket. The pin of the coupler cam may be positioned in the hole of the bracket to secure the pin to the bracket.

In some embodiments of the first aspect, each of the pair of arms may form protuberant sections that define a space therebetween. The pin of the coupler cam, when positioned in the hole of the bracket, may extend into the space between the protuberant sections. The pin may constrain movement of the bias member relative to the bracket.

In some embodiments of the first aspect, the bias member may engage with the bracket such that portions of the bias member are free to move relative to the bracket.

In some embodiments of the first aspect, the bias member may comprise a body that is symmetrical about a centerline. The body may have a top with a first side that has a generally planar first surface and a second generally planar second surface offset from the first surface. The body may have a first end having a first width, symmetrical side walls that define an increasing width of the body for a first distance and a decreasing width of the body for a second distance terminating at the second end, the pair of arms extending from the second end.

In some embodiments of the first aspect, the arms may form complex curvilinear structures that are symmetrical about the centerline. The arms may each have a protuberant first section that extends from the second end in a first direction. When present, the protuberant first section may curve around to have a second section flaring out from the body to a free end. In some embodiments the arm may have a varying width to control the spring rate of the arm.

In some embodiments of the first aspect, the arms may form leaf springs.

In some embodiments of the first aspect, the body may have a bottom, opposite the top, with a mounting flange extending from the bottom.

In some embodiments of the first aspect, the thickness of the leaf springs may vary along the length of the leaf spring to vary the spring rate of the leaf spring.

In some embodiments of the first aspect, the bias member may comprise a body and a pair of leaf springs that extend from the body. The leaf springs may be positioned on opposite sides of the body.

In some embodiments of the first aspect, the leaf springs may engage the motion limiters.

In some embodiments of the first aspect, a first one of the pair of leaf springs may deflect when the handle is moved in a first direction and a second of the pair of leaf springs may disengage the respective motion limiter when the handle is moved in the first direction.

In some embodiments of the first aspect, the first one of the pair of leaf springs may urge the activation assembly to the neutral position when the handle is released.

In some embodiments of the first aspect, the activation assembly may further comprise a coupler cam and a switch assembly having an activation arm. The coupler cam may be positioned on the pivot pin and pivotable about the pivot pin. The coupler cam may be secured to the bracket to move with the bracket about the pivot pin. The coupler cam may include a cam surface engaging the activation arm of the switch assembly. The coupler cam may activate the switch when the activation assembly is moved from the neutral position to an activated position.

In some embodiments of the first aspect, the arms form complex curvilinear structures that are symmetrical about the centerline. The arms each may have a protuberant first section that extends from the second end in a first direction. The protuberant first section may curve around to have a second section flaring out from the body to a free end. The arm may have a varying width to control the spring rate of the arm. In some embodiments, the arms may form leaf springs.

In some embodiments of the first aspect, a first one of the pair of arms may deflect when the handle is moved in a first direction and a second of the pair of arms may disengage the respective motion limiter. In some embodiments, the first one of the pair of arms urges the activation assembly to the neutral position when the handle is released.

The invention will now be further described by way of example with reference to the accompanying drawings, in which:
The detailed description particularly refers to the accompanying figures in which:.

<FIG> shows a portion of a patient support apparatus <NUM> that includes similar CPR activation assemblies <NUM>, <NUM>' of the present disclosure positioned on opposite sides of a head deck section <NUM>. <FIG> depicts an upper frame <NUM> and the head deck section <NUM> of a patient support apparatus <NUM> similar to the patient support apparatus disclosed in <CIT> and titled PATIENT SUPPORT APPARATUS, which is incorporated by reference herein for the disclosure of the details of a patient support apparatus which may alternatively include the activation assemblies <NUM>, <NUM>' of the present disclosure.

Referring to <FIG>, the activation assemblies <NUM>, <NUM>' are operable to transfer motion to a release mechanism <NUM> of a head deck section drive <NUM>. There are a multitude of linear actuator assemblies and hydraulic cylinders that may be released by motion of a linkage or a cable assembly to release portions of the drive to move without being driven by a motor or hydraulic fluid. In many cases, the release mechanism is actuated by a caregiver to cause the bed section to be moved under gravity in an emergency situation. For example, the head deck section <NUM> may be released to lower to a flat configuration when a patient experiences cardiac arrest so that the caregiver(s) may provide emergency cardiopulmonary resuscitation on the patient. The focus of the present disclosure is on the activation assembly <NUM> which provides a particular approach for facilitating activation of the release mechanism(s) of known drive systems.

As a reference, <FIG> show details of activation assembly <NUM>' and <FIG>, <FIG>, and <FIG> shown details of activation assembly <NUM>. The component parts of each of the activation assemblies <NUM>, <NUM>' are the same, but the two activation assemblies <NUM>, <NUM>' are mirrored. Referring now to <FIG>, the activation assembly <NUM>' is shown with a head panel <NUM> (seen in <FIG> and <FIG>) removed so that the view is shown from the perspective of the arrow <NUM> shown in <FIG>. <FIG> shows the activation assembly <NUM>' in a neutral position such that a cable <NUM> of a cable assembly <NUM> and an activation arm <NUM> of a switch assembly <NUM> are in a neutral position. <FIG> shows the activation assembly <NUM> activated so that the cable <NUM> is extended and the activation arm <NUM> is moved to an activated position. When activated, the activation assembly <NUM> transfers motion to cable <NUM> which thereby acts on the release mechanism <NUM> to release the head deck section drive <NUM>.

In addition, the activation arm <NUM> of the switch assembly <NUM> causes the switch to be activated to provide a signal to an electrical system of the patient support apparatus <NUM>. This signal may be used by the patient support apparatus <NUM> to inform other systems of the patient support apparatus <NUM> to respond to the activation of the activation assembly <NUM> or may be sent to a hospital network to inform others that the activation assembly <NUM> has been activated.

The limit switch <NUM> is held in position by a limit switch clip <NUM> shown in <FIG>. Referring to <FIG>, the limit switch clip <NUM> includes two grip arms <NUM>, <NUM> that are configured to secure the limit switch <NUM> against the support <NUM> with a snap-fit. A surface <NUM> of the limit switch <NUM> is engaged by respective grip surfaces <NUM>, <NUM> (see <FIG>) of the respective grip arms <NUM>, <NUM>. Referring to <FIG> and <FIG>, the clip <NUM> is inserted through holes (not shown) formed in the support <NUM> with a base <NUM> having a surface <NUM> that engages the support <NUM>. A pair of posts <NUM> and <NUM> are inserted through the support and the limit switch <NUM> is fitted onto the posts <NUM> and <NUM>, the posts <NUM> and <NUM> serving to prevent rotation of the limit switch <NUM>. The grip arms <NUM> and <NUM> are also formed to include respective grips <NUM> and <NUM> that act to secure the clip <NUM> to the support <NUM> even when the limit switch <NUM> is not present. As the arms <NUM>, <NUM> are inserted through the support <NUM>, they deflect as suggested by the respective arrows <NUM>, <NUM> until the clip <NUM> is fully inserted. Once the clip <NUM> is inserted, the arms <NUM>, <NUM>, which are resiliently flexible, return to a neutral position such that the grips <NUM>, <NUM> snap-fit securely to the support <NUM>. To insert the limit switch, the arms <NUM>, <NUM> are deflected in the opposite direction until the surface <NUM> slips under the grips <NUM>, <NUM> and the arms <NUM>, <NUM> are permitted to return to their neutral position securing the limit switch <NUM> with a snap fit.

Referring again to <FIG>, it can be seen that the activation assembly <NUM> includes a bias member <NUM>, a bracket <NUM>, and a handle <NUM>, supported from the bias member <NUM> and bracket <NUM>. The bias member <NUM>, a bracket <NUM>, and handle <NUM> pivot together about a pivot pin <NUM> which defines a pivot axis <NUM>. The bracket <NUM> is formed to include a lever arm <NUM> which transfers motion to the cable <NUM>. While the present disclosure shows the lever arm <NUM> coupled to a cable <NUM>, it should be understood that the lever arm <NUM> may act on any of a number of structures which transfer motion to a release mechanism without use of electrical power. For example, in some embodiments the cable assembly <NUM> may be omitted and replaced with a wire form or other fixed linkage. In still other embodiments, the lever arm <NUM> may be connected to a valve which causes fluid or air to be released from a hydraulic or pneumatic system to allow a cylinder to be lowered in an emergency and without electrical power.

The activation assembly <NUM> is supported from a support <NUM> coupled to a frame member <NUM> of the head deck section <NUM> with the pivot pin <NUM> securing the bias member <NUM>, a bracket <NUM>, handle <NUM>, and a coupler cam <NUM> to the support <NUM> such that the bias member <NUM>, a bracket <NUM>, and handle <NUM> pivot relative to the support <NUM>. It should be noted that the coupler cam <NUM> is reversed in activation assembly <NUM> as compared to activation assembly <NUM>' as the bracket <NUM> can be used with either activation assembly <NUM> or <NUM>' with only one of two holes <NUM> or <NUM> used, depending on which side of the head deck section <NUM> the activation assembly <NUM> or <NUM>' is positioned. The activation assembly <NUM> further includes first and second opposed motion limiters <NUM> and <NUM> which are engaged by the bias member <NUM> as will be described in further detail below. The motion limiters <NUM> and <NUM> are embodied as flanges of a cover <NUM> that is secured to the frame member <NUM> and support <NUM>. However, in other embodiments, the motion limiters <NUM> and <NUM> may be embodied as any structure that is fixed relative to the support so that movement of the bias member <NUM> relative to the support <NUM> may be resisted by the motion limiter <NUM> or <NUM>. The cover <NUM> provides protection to the activation assembly <NUM> to reduce the potential for intrusion of fluids and/or biomaterials into the operating mechanism of the activation assembly <NUM>.

The switch assembly <NUM> and a sheath <NUM> of the cable assembly <NUM> are fixed relative to the support <NUM> so that there is relative motion of the bias member <NUM>, bracket <NUM>, and handle <NUM> to the switch assembly <NUM> and sheath <NUM> that results in activation of the activation arm <NUM> and, thereby, cable <NUM>. The activation assembly <NUM> further includes a coupler cam <NUM> which is secured to the bracket <NUM> by the pivot pin <NUM> and a pin <NUM> which extends from a body <NUM> of the coupler cam <NUM> as shown in <FIG>. The pin <NUM> extends through a hole <NUM> formed in the bracket <NUM> (seen in <FIG>) and which limits movement of the bias member <NUM> as will be discussed below. The pivot pin <NUM> extends through passageway <NUM> (see <FIG>) formed in the coupler cam <NUM> and through bracket <NUM> as shown in <FIG>. The pivot pin <NUM> includes a cross hole <NUM> which receives a cotter pin, spring pin, or the like, to secure the pivot pin <NUM>. The coupler cam <NUM> moves freely relative to the pivot pin <NUM> with sufficient clearance in the passageway <NUM> for freedom of movement, but the pin <NUM> secures the coupler cam <NUM> to the bracket <NUM> so that the coupler cam <NUM> moves with the bias member <NUM>, bracket <NUM>, and handle <NUM>.

When the coupler cam <NUM> moves about pivot pin <NUM>, a cam surface <NUM> acts on a hook <NUM> of the activation arm <NUM> of the switch assembly <NUM>. The cam action of the coupler cam <NUM> and hook <NUM> (see <FIG>) displaces the activation arm <NUM> to cause the switch assembly <NUM> to be activated and provide an electrical signal to a control system of the patient support apparatus <NUM>.

Referring now to <FIG> and <FIG>, the bias member <NUM> is shown in additional detail. The bias member <NUM> includes a body <NUM>, a mounting flange <NUM> extending from the body <NUM> in a first direction, a guide flange <NUM> extending from the body <NUM> in a second direction that is orthogonal to the first direction, and a pair of arms <NUM>, <NUM> that have a curvilinear shapes that are mirror images of each other. The arms <NUM> and <NUM> are mirror images of each other about a centerline <NUM> of the body <NUM>. The bias member <NUM> is formed monolithically in the illustrative embodiment and comprises a flexible material that deflects under a load, but is resiliently flexible such that the arms <NUM> and <NUM> are biased to return to a neutral position. The bias member <NUM> further includes two protrusions <NUM>, <NUM> that extend from the body <NUM> in the first direction on opposite sides of the centerline <NUM>. The protrusions <NUM>, <NUM> cooperate with the pin <NUM>, bracket <NUM>, and flanges <NUM>, <NUM> to control the movement of the bias member <NUM>, and, thereby, other components of the activation assembly <NUM>, <NUM>'. The protrusions <NUM>, <NUM> are, when the activation assembly <NUM>, <NUM>' is assembled, received in respective slots <NUM>, <NUM> formed in the bracket <NUM> which limit movement of the bias member <NUM> relative to the bracket <NUM>. Additionally, the pin <NUM> is positioned in the hole <NUM> formed in the bracket <NUM> and extends into a space <NUM> formed between two protuberant portions <NUM>, <NUM> of the respective arms <NUM>, <NUM>. The bias member <NUM> is free to move relative to the pin <NUM>, however, extensive movement of the bias member <NUM> is limited when the pin <NUM> contacts either of the respective arms <NUM>, <NUM>.

The body <NUM> is symmetrical about the centerline <NUM> includes a top <NUM> with a first side <NUM> that has a generally planar first surface <NUM> and a second generally planar second surface <NUM> offset from the first surface. The body <NUM> also includes a first end <NUM> having a first width <NUM> and symmetrical side walls <NUM>, <NUM> that define an increasing width of the body for a first distance <NUM> and a decreasing width of the body for a second distance <NUM> terminating at the second end <NUM>. The arms <NUM>, <NUM> extend from the second end.

The arms <NUM>, <NUM> form complex curvilinear structures that are symmetrical about the centerline <NUM>. The protuberant first sections <NUM>, <NUM> extend from the second end <NUM> in the first direction and curve around to have a second section <NUM> flaring out from the body <NUM> to a free end <NUM>, <NUM>. The arms <NUM>, <NUM> have a varying width to control the spring rate of the arms <NUM>, <NUM>. Each of the arms <NUM>, <NUM> form leaf springs.

The bracket <NUM> further includes a flange <NUM> which is configured to engage the mounting flange <NUM> of the bias member <NUM>. When the flange <NUM> is engaged with the mounting flange <NUM>, two holes <NUM>, <NUM> formed in the flange <NUM> align with two holes <NUM>, <NUM> formed in the mounting flange <NUM> so that fasteners <NUM> (see <FIG> and <FIG>) may be extended therethrough to secure the handle <NUM> to the bias member <NUM> and bracket <NUM> so that they all move together. Referring to <FIG>, the bracket <NUM> includes a planar body <NUM> from which the flange <NUM> extends. In addition, the bracket <NUM> includes an offset backing flange <NUM> from which the lever arm <NUM> extends. The backing flange <NUM> is coupled to the body <NUM> by a pair of legs <NUM>, <NUM> which space the backing flange <NUM> apart from the body <NUM> to define a space <NUM> into which the body <NUM> and arms <NUM>, <NUM> of the bias member <NUM> are positioned when the activation assembly <NUM>, <NUM>' is assembled. Referring to <FIG>, there are two holes <NUM>, <NUM> in the body <NUM> which are aligned with another pair of matching holes <NUM>, <NUM> in the backing flange <NUM> through which the pivot pin <NUM> extends when activation assembly <NUM> or <NUM>' assembled, respectively.

Referring to <FIG>, when a load is applied to a grip <NUM> of the handle <NUM> is pulled outwardly by a user, the bias of the arm <NUM> is overcome such that the assembled bias member <NUM>, bracket <NUM>, and handle <NUM> rotate about the pivot axis <NUM> and a surface <NUM> (see <FIG>) of the arm <NUM> engages a surface <NUM> of the flange <NUM>. Because the bias member <NUM> is only fully constrained by the engagement with the pivot pin <NUM> the bias member <NUM>, being resiliently flexible, is relatively free to move relative to the bracket <NUM> so that there are no specific locations of significant stress through the motion of the handle <NUM> and until the body <NUM> of the bias member <NUM> engages the arm <NUM>. However, in use, the cable <NUM> is adjusted such that the release mechanism reaches the end of travel prior to, or coordinated with the engagement of the body <NUM> with the arm <NUM>, thereby greatly reducing the potential for damage to the bias member <NUM> of other components of the activation assembly <NUM>, <NUM>' during the adrenaline filled actuation of the activation assembly <NUM>, <NUM>' that occurs during an emergency.

Claim 1:
A patient support apparatus (<NUM>) comprising:
a first frame (<NUM>);
a second frame (<NUM>) pivotably coupled to the first frame (<NUM>);
a drive (<NUM>) secured to the first frame (<NUM>) and the second frame (<NUM>), the drive (<NUM>) operable to move the second frame (<NUM>) relative to the first frame (<NUM>), wherein the drive (<NUM>) includes a release mechanism (<NUM>) which is operable to disengage a portion of the drive (<NUM>) to allow the second frame member (<NUM>) to move freely relative to the first frame (<NUM>); and
an activation assembly (<NUM>) for activating the release mechanism (<NUM>) of the drive (<NUM>), the activation assembly (<NUM>) including:
a pivot pin (<NUM>) configured to engage with the second frame (<NUM>);
a bracket (<NUM>) positioned on the pivot pin (<NUM>) and pivotable about the pivot pin (<NUM>) relative to the second frame (<NUM>), the bracket (<NUM>) including a lever arm (<NUM>) configured to engage a motion transfer link (<NUM>) coupled to the release mechanism (<NUM>) such movement of the lever arm (<NUM>) is transferred through the transfer link (<NUM>) to the release mechanism (<NUM>);
a bias member (<NUM>) engaged with the bracket (<NUM>) to move with the bracket (<NUM>) and configured to engage a pair of spaced apart motion limiters (<NUM>, <NUM>) secured to the second frame (<NUM>), the bias member (<NUM>) including a body (<NUM>) and a pair of arms (<NUM>, <NUM>) positioned on opposite sides of the body (<NUM>), the arms (<NUM>, <NUM>) each configured to engage a respective motion limiter (<NUM>, <NUM>) and maintain engagement with both motion limiters (<NUM>, <NUM>) when the activation assembly (<NUM>) is in a neutral state; and
a handle (<NUM>) coupled to the bias member (<NUM>), the movement of the handle (<NUM>) resisted by the bias member (<NUM>) and transferred from the handle (<NUM>) to the lever arm (<NUM>).