Patient handling apparatus with hydraulic control system

A patient handling apparatus includes a frame, a base, and a lift assembly supporting the frame relative to the base, the lift assembly configured to extend or contract to raise or lower the base or the frame with respect to the other of the base and the frame. The patient handling apparatus further includes a control system, which comprises at least one hydraulic cylinder to extend or contract the lift assembly, a hydraulic circuit to direct the flow of hydraulic fluid to and from the hydraulic cylinder, and a controller operable to control the hydraulic circuit. Based on an input signal, for example, an input signal that is indicative of a status or condition of the patient handling apparatus, the controller is configured to open, optionally automatically, fluid communication between the rod end chamber and the cap end chamber to redirect a portion of the fluid output from the rod end chamber to the cap end chamber when the rod is extending to thereby increase the extension speed of the rod.

TECHNICAL FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to a patient handling apparatus, such as emergency cot, medical bed, stretcher, stair chair, or other apparatuses that support a patient and, more particularly, to a patient handling apparatus that provides a control system that can increase the deployment speed of a component of the patient handling apparatus.

For example, when a patient handling apparatus, such as an emergency cot, is unloaded from an emergency vehicle, such as an ambulance, the patient handling apparatus must typically be moved out of the vehicle sufficiently far where the base of the patient handling apparatus clears the ambulance deck and bumper so that the base can then be lowered. The faster the base can be lowered, the faster the patient handling apparatus can be unloaded, and the quicker the patient can be retrieved and delivered to the medical facility, typically an emergency room. Therefore, quick deployment of the base can be critical in some cases.

Accordingly, there is a need to provide a patient handling apparatus with a control system that can quickly move one component relative to another component, such as an emergency cot's base relative to the cot's frame.

SUMMARY OF THE INVENTION

Accordingly, the patient handling apparatus provides a lift assembly with a hydraulic system that can move one of the components relative to the other components more quickly when needed.

In one form, a patient handling apparatus includes a frame, a base, and a lift assembly supporting the frame relative to the base. The lift assembly is configured to extend or contract to raise or lower the base or the frame with respect to the other. The patient handling apparatus also includes at least one hydraulic cylinder to extend or contract the lift assembly, which has a rod, a cap end chamber, and a rod end chamber. The patient handling apparatus also includes a control system with a hydraulic circuit operable to direct the flow of hydraulic fluid to and from the hydraulic cylinder. The control system is configured to open fluid communication between the rod end chamber and the cap end chamber based on an input signal, for example an input signal that is indicative of a status or condition of the patient handling apparatus, to redirect a portion of the fluid output from the rod end chamber to the cap end chamber to thereby increase the extension speed of the rod.

In one aspect, the control system is configured to detect the presence or absence of an external force being applied to the base. The input signal is generated when the control system detects the absence of an external force being applied to the base.

In a further aspect, the control system is configured to no longer redirect the fluid output from the rod end chamber to the cap end chamber when the rod is retracting.

In another aspect, the control system is configured to (1) no longer redirect the fluid output from the rod end chamber to the cap end chamber and/or (2) stop the flow of fluid to the hydraulic cylinder when an external force is applied to the base.

In yet another aspect, the hydraulic circuit includes a valve to control the fluid communication between the rod end chamber and the cap end chamber, and the control system is configured to control the valve. For example, the valve may comprise a solenoid valve, with the control system in communication with the solenoid valve to control the opening or closing of the solenoid valve.

According to yet other aspects, the control system includes a sensor configured to detect the absence or presence of an external force applied to the base, and the control system is configured to open the valve in the absence of an external force applied to the base and when the rod is extending.

In addition, the control system may be configured to control the valve when the control system detects the presence of an external force applied to the base and/or slow or stop the flow of fluid to the hydraulic cylinder.

In other aspects, the control system further includes an apparatus-based communication system for communicating with a loading and unloading apparatus based communication system on a loading and unloading apparatus. For example, the apparatus-based communication systems may be wireless, such as RF communication systems.

In a further aspect, the control system is operable to open or close the solenoid valve based on a signal received from the loading and unloading based communication system.

According to other aspects, the patient handling apparatus further includes a motor to run the pump, wherein the control system is configured to detect a load on the motor (or the pump). For example, the input signal is a function of when the load on the motor. And, the control system may be configured to (1) no longer redirect fluid from the rod end chamber to the cap end chamber and/or (2) stop or slow the fluid flow to the hydraulic cylinder when the load on the motor is near, is at, or exceeds a prescribed value.

In yet other aspects, the control system is configured to detect the location of the frame relative to the base, and further is configured to close fluid communication between the rod end chamber and the cap end chamber when the base is at a prescribed location relative to the frame.

According to yet another aspect, the control system is configured to detect the location of the frame relative to the base or when the lift assembly is in a prescribed configuration and further is configured to (1) no longer redirect the fluid output from the rod end chamber to the cap end chamber and/or (2) slow or stop the flow of fluid to said hydraulic cylinder when said frame is near or at the prescribed location or the lift assembly is near or in the prescribed configuration.

In another embodiment, a patient handling apparatus includes a frame, a base, and a lift assembly supporting the frame relative to the base. The lift assembly is configured for extending or contracting to raise or lower the base or the frame with respect to the other of the base and the frame. The patient handling apparatus also includes a hydraulic cylinder and a hydraulic circuit controlling flow of hydraulic fluid to and from the hydraulic cylinder, and a control system (which includes a sensor) to control the hydraulic circuit. Based on an input signal from or status of the sensor, the control system is configured to redirect the fluid output from the rod end chamber to the cap end chamber when the rod is extending to thereby increase the extension speed of the rod.

In one aspect, the sensor detects the presence or absence of an external force being applied to the base.

In another aspect, the patient handling apparatus also includes a motor, and the hydraulic circuit includes a pump. The sensor detects the load on the motor or the pump.

In another aspect, the sensor detects the location of the base relative to the frame.

According to yet another aspect, the sensor detects the configuration of the lift assembly.

In another embodiment, a method of unloading a patient handling apparatus from a cargo area of an emergency vehicle includes moving the patient handling apparatus adjacent an opening to the cargo area of an ambulance and extending the base of the patient handling apparatus beyond the cargo area wherein the base is no longer supported by the emergency vehicle, and directing hydraulic fluid to the cap end of the hydraulic cylinder to extend the rod. The method further includes automatically redirecting a portion of the hydraulic fluid discharged from the rod end chamber of the hydraulic cylinder to the cap end chamber of the hydraulic cylinder to increase the speed of the rod when the rod is extending.

In one aspect, the method further includes stopping or slowing the flow of fluid to the hydraulic cylinder and/or terminating the redirecting when an external force is applied to the base.

In another aspect, the method further includes detecting when the base is supported by or contacts a ground surface, and stopping or slowing the flow of fluid to the hydraulic cylinder and/or terminating the redirecting when sensing that the base is supported by or contacts a ground surface.

In yet another aspect, the method further includes stopping or slowing the flow of fluid to the hydraulic cylinder and/or terminating the redirecting when the base is near or at a prescribed location relative to the frame. Additionally, the method includes sensing when the base is near or at the prescribed location relative to the frame.

According to yet another aspect, the method further includes stopping or slowing the flow of fluid to the hydraulic cylinder and/or terminating the redirecting based on the lift assembly being near or having a prescribed configuration. Additionally, the method includes sensing the configuration of the lift assembly, and comparing the configuration of the lift assembly to the prescribed configuration.

Accordingly, the present invention provides a patient handling apparatus with an improved control system that can quickly move one component relative to another, for example, in an emergency situation, in response to a variety of different conditions at the patient handling apparatus.

These and other objects, advantages, purposes and features of the invention will become more apparent from the study of the following description taken in conjunction with the drawings.

DETAILED DESCRIPTION OF THE INVENTION

Referring toFIG. 1, the numeral10generally designates a patient handling apparatus. The term “patient handling apparatus” is used broadly to mean an apparatus that can support a patient, such as a medical bed, including an apparatus that can transport a patient, such as an emergency cot, a stretcher, a stair chair, or other apparatuses that support and/or transport a patient. Further, the term “patient” is used broadly to include persons that are under medical treatment or an invalid or persons who just need assistance. Although the patient handling apparatus10is illustrated as an emergency cot, the term “patient handling apparatus” should not be so limited.

Referring again toFIG. 1, patient handling apparatus10includes a frame12, which in the illustrated embodiment comprises a litter frame that supports a litter deck (not shown), and a base18. As will be more fully described below, patient handling apparatus10includes a lift assembly20that raises or lowers the base18or the frame12with respect to the other so that the patient handling apparatus10can be rearranged between a more compact configuration, for example, for loading into an emergency vehicle, such as an ambulance, and a configuration for use in transporting a patient across a ground surface. Further, as will be more fully described below, the mounting of lift assembly20to the frame12is optionally configured to allow the frame12to be tilted relative to the lift assembly20so that one end (e.g. head-end or foot-end) of the frame12can be raised beyond the fully raised height of the lift assembly to allow the patient handling apparatus to be inserted more easily into the compartment of an emergency vehicle.

Referring again toFIG. 1, frame12is mounted to base18by lift assembly20, which includes load bearing members22pivotally coupled to the frame12and to the base18. In the illustrated embodiment, load bearing members22are pivotally coupled to the frame12by head-end upper pivot connections24aand foot-end upper pivot connections24b. Further, as will be more fully described below, head-end upper pivot connections24aare fixed to the frame12along the longitudinal axis12bof frame12and foot-end upper pivot connections24bare movable so that the head-end of frame12can be tilted upwardly, as more fully described below.

In the illustrated embodiment, each load bearing member22comprises a telescoping compression/tension member42. Compression/tension members42may be pivotally joined at their medial portions about a pivot axis to thereby form a pair of X-frames44(FIG. 2). The upper ends of each X-frame44are, therefore, pivotally mounted to the frame12by head-end upper pivot connections24aand foot-end upper pivot connections24b. The lower ends of each X-frame44are pivotally mounted to the base18by head-end lower pivot connections26aand foot-end lower pivot connections26b. However, it should be understood that load bearing members22may comprise fixed length members, for example such of the type shown in U.S. Pat. No. 6,701,545, which is commonly owned by Stryker Corp. of Kalamazoo, Mich. and incorporated herein by reference in its entirety.

In addition to load bearing members22, patient handling apparatus10includes a pair of linkage members50and52(FIG. 1), which are pivotally mounted on one end to transverse frame members18bof base18and on their other ends to brackets54,56(FIG. 1), which mount to the X-frames and also provide a mount for a linear actuator30(FIG. 1), which extends or contracts the lift assembly to raise or lower frame14relative to the base18(or raise or lower base relative to the frame12) described below. Brackets54and56therefore, pivotally mount linkage members50and52, as well as actuator30(described below), to the X-frames44so that member50,52provide a timing link function as well as a moment coupling function. It should be understood that multiple actuators may be used to raise or lower frame12.

As best seen inFIG. 1, base18is formed by longitudinal frame members18aand transverse frame members18b, which are joined together to form a frame for base18. Mounted to the longitudinal frame members18aare bearings18c, such as wheels or castors. Transverse frame members18bprovide a mount for the lower pivot connections24a,24bof load bearing members22and also for the rod end of the actuator30. As described above, the upper end of actuator30is mounted between the X-frames (formed by load bearing members22) by a transverse member30a(FIG. 1A) that is mounted to brackets54,56.

As noted above, lift assembly20is extended or contracted by actuator30. In the illustrated embodiment actuator30comprises a hydraulic cylinder80, which is controlled by a control system82. Although one actuator is illustrated, it should be understood that more than one actuator or cylinder may be used. As will be more fully described below, control system82includes a hydraulic circuit90and a controller120, which is in communication with hydraulic circuit and a user interface120athat allows an operator to select between the lifting, lowering, raising and retracting functions described herein. For example, user interface controls120amay have a touch screen with touch screen areas or may comprise a key pad with push buttons, such as directional buttons, or switches, such as key switches, that correspond to the lifting, lowering, raising, and retracting functions described herein to allow the user to select the mode of operation and generate input signals to controller120. As will be more fully described below, the controller120may also automatically control the mode of operation.

Referring again toFIGS. 6-8, cylinder80includes cylinder housing84with a reciprocal rod86. Mounted at one end of rod86is a piston88, which is located within the cylinder housing84. The distal end of the reciprocal rod86is extended from housing85and connected in a conventional manner to transverse member18bof base18. And as described above, the other end or fixed end (or cap end) of cylinder80is mounted between brackets54,56.

Cylinder80is extended or retracted by control system82to extend or contract lift assembly20and generally operates in four modes, namely (mode 1) to raise the frame12when base18is supported on, for example, a ground surface (FIG. 6), (mode 2) to lower the frame12when base18is supported on, for example, a ground surface (FIG. 7), (mode 3) to lower or extend base18when apparatus10is its compact configuration and when the frame12is supported, for example, by an attendant or a loading and unloading apparatus (FIG. 8), or (mode 4) to raise base18when apparatus10is its extended configuration and when the frame12is supported, for example, by an attendant or a loading and unloading apparatus (FIG. 7). As will be more fully described below, when lowering or extending base18relative to frame12(when frame12is supported) control system82is configured to automatically lower or extend base18at a faster speed unless certain conditions exist.

Referring toFIGS. 6-8, hydraulic circuit90includes a pump92, which is in fluid communication with a fluid reservoir R, to pump fluid from the reservoir R to the cylinder80. As best seen inFIG. 6, when a user selects the first mode of operation (via the user interface) to raise or lift the frame12, controller120powers motor94, which operates pump92to pump fluid from the reservoir R, through filters92band check valves92a, into the hydraulic circuit90to direct the flow of fluid to cylinder80. To avoid over pressurization, for example, when a heavy patient is supported on frame12, fluid may be discharged from the hydraulic circuit90, for example, when the pressure in the hydraulic circuit90exceeds a designated pressure (e.g. 3200 psi on the cap side of the hydraulic circuit, and 700 psi on the rod side of the hydraulic circuit) through pressure relief valves90aand90b. It is to be understood that the pump92, cylinder80, and the various conduits carrying hydraulic fluid to the cylinder are preferably always filled with hydraulic fluid. Pump92is driven by an electric motor94(both of which are optionally reversible), which motor is controlled by controller120to thereby control pump92.

Referring again toFIG. 6, when an operator wishes to raise frame12relative to base18(mode 1), and base18is supported on a support surface, the operator, using interface controls120a(FIG. 6), generates input signals that are communicated to controller120. When operating in the first mode (mode 1), the output of the pump92(in the direction indicated by the arrows inFIG. 6), will supply hydraulic fluid through a hydraulic conduit96, which includes a pilot operated check valve98, to the cap end chamber84aof the cylinder housing84, which is on the piston side of rod86. When fluid is directed to cap end chamber84a, the rod86will extend to raise the frame12relative to base18at a first speed. This mode of operation is used when base18is supported on a support surface, such as the ground, which can be detected by a controller120in various ways described below. It should be understood, that mode 1 may also be used to lower or extend base18when the faster speed of mode 3 described below is not appropriate or desired.

Referring toFIG. 7, when an operator user wishes to select mode 2 or 4—that is lower the frame12relative to base18(when base18is supported on a support surface) or raise base18relative to frame12(when frame12is supported), using interface controls120a, the operator will generate an input signal to controller120that will cause controller120to operate in mode 2 or 4. In mode 2 or 4, the direction of pump92is reversed, so that fluid will flow in an opposite direction (see arrows inFIG. 7) to cylinder80through a second hydraulic conduit100, which is in fluid communication and connected to the rod end chamber84bof the cylinder housing84. Conduit100includes a check valve assembly102, with an orifice or fluid throttle104and a poppet or check valve106in parallel, to control the flow of fluid through conduit100. Fluid flow in this direction will cause the rod86to retract and raise the base12when the frame12is supported or lower the frame12relative to base18when the base18is supported. Also provided is a pilot operated check valve108connected between the valve assembly102and pump92. Optionally, valves98and108are provided by a dual pilot operated check valve assembly110, which includes both valves (98and108) and allows fluid flow through each respect conduit in either direction. The valves98and100of the dual pilot check valve are operated by the fluid pressure of the respective branch of fluid conduit (96or100) as well as the fluid pressure of the opposing branch of fluid conduit (96or100), as schematically shown by the dotted line inFIGS. 6-8.

Referring toFIG. 8, when an operator selects the base18lowering function and the litter is supported (and the base is unsupported), controller120will automatically increase the speed of the cylinder80over the first speed (mode 3) (as would be understood by those skilled in the art, the speed of the cylinder or cylinders may be increased by increasing the flow of hydraulic fluid and/or pressure of the hydraulic fluid flowing to the cylinder (s)) unless certain conditions exist. Optionally, user interface120amay allow an operator to generate an input signal to select mode 3 and/or to disable mode 3.

In order to speed up the extension of rod86when operating in mode 3, hydraulic circuit90includes a third hydraulic conduit112, which is in fluid communication with conduits96and100via a check valve114, to thereby allow fluid communication between the cap end chamber84aand the rod end chamber84band to allow at least a portion of the fluid output from the rod end chamber84bto be redirected to the cap end chamber84a, which increases the speed of the rod86(i.e. by increasing the pressure and/or fluid flow of the fluid delivered to the end cap chamber84a).

To control (e.g. open and close) fluid communication between the cap end chamber84aand rod end chamber84bvia conduit112, conduit112includes a valve116, such as a solenoid valve or a proportional control valve, which is normally closed but selectively controlled (e.g. opened) to open fluid communication between the rod end chamber84band the cap end chamber84aas described below. As noted, this will allow at least a portion of the fluid output from the rod end chamber84bto be redirected to the end cap chamber84ato thereby increase the speed of rod86. Optionally, an additional valve, such as a solenoid valve, may be included in conduit100, for example, between conduit112and pump92, which is normally open but can be selectively controlled (e.g. closed), so that the amount of fluid (and hence fluid pressure and/or fluid flow) that is redirected from the rod end chamber84bmay be varied. For example, all the fluid output from may be redirected to the cap end chamber84a. In another embodiment, an additional electrically operated proportional control valve may be used in any of the branches of the conduit (e.g.96,100, or112) to control the rate of fluid flow through the respective conduits and thereby control and vary the speed of the extension of rod86.

As noted above, control system82includes controller120, which is also schematically represented inFIG. 6. Controller120may be powered by the battery (not shown) on board the patient handling apparatus10. A hydraulic fluid pressure monitoring device (not shown) may be connected to the hydraulic circuit90to provide a signal to controller120indicative of the magnitude of the fluid pressure, which may be used as input when controlling the hydraulic cylinder80.

Referring again toFIG. 6, controller120may be in communication with one or more sensors, which generate input signals to controller120(or controller120may detect the state of the sensor) to allow controller120to adjust the hydraulic circuit based on an input signal or signals from or the status of the sensors, described more fully below. Suitable sensors may include Hall Effect sensors, proximity sensors, reed switches, optical sensors, ultrasonic sensors, liquid level sensors (such as available from MTS under the brand name TEMPOSONIC), linear variable displacement transformer (LVDT) sensors, or other transducers or the like.

For example, controller120may control (e.g. open or close) the valve116to increase or stop the increased speed of cylinder80and/or slow or stop the pump to slow or stop the cylinder, or any combination thereof based on an input signal or signals from or the status of the sensor(s). Further, controller120may control (e.g. close) the valve116before, after, or at the same time as slowing or stopping the pump based on an input signal or signals from or the status of the sensor(s). Alternately, controller120may slow or stop the pump P in lieu of control (e.g. close) the valve116based on an input signal or signals from or the status of the sensor(s).

In one embodiment, control system82may include one or more position sensors provided on the patient handling apparatus10. More specifically, control system82may include one or more sensors122(FIG. 6) that are used to detect when the base18of the patient handling apparatus10is contacting the ground or other surface, such as a bumper or another obstruction, which, as noted, may be used as an input signal or signals to the controller120to control the hydraulic circuit90. A suitable sensor may include a transducer, such as a pressure sensor, including a load cell, for example, mounted to one or more of the wheels or casters, which detect when an upward force is applied to the wheels or casters. Alternately, as described below, control system82may include one or more sensors to detect the increase in the load on the motor, for example, by detecting an increase in the motor's current, to detect when the base18is supported. Other suitable sensors (as noted above) may be used.

For example, when control system82detects that the base18is contacting or nearly contacting a ground surface or an obstruction, controller120may be configured to close valve116to no longer allow fluid communication between the rod end chamber84band the cap end chamber84avia conduit112and, further, to stop the pump. In this manner, cylinder80will not be driven at the increased speed and, further, optionally stopped when base18is supported, for example on the deck of the emergency vehicle or when it is supported on a ground surface, or if it encounters an obstruction. Additionally, controller120may slow or stop the pump, either before, after or at the same time as closing valve116, or instead of closing valve116. Optionally, before, after or at the same time as closing valve116, controller may reverse the motor to avoid excess pressure build up in the hydraulic circuit90.

So for example, if an attendant is removing patient handling apparatus from an emergency vehicle, and the operator has selected a lowering base function, and controller120detects that the base18is no longer supported, controller120will automatically open valve116so that cylinder80will be driven at the increased speed. On the other hand, once base18contacts or nearly contacts the ground surface and/or the base18is fully or nearly fully lowered, as will be more fully described below, controller120may close valve116so that cylinder80can no longer be driven at the increased speed and, further, may stop pump92so that cylinder80will no longer extend. As noted above, controller120may reverse the motor to avoid excess pressure in hydraulic circuit90. Further, as noted, controller120may optionally stop pump92in lieu of closing valve116.

In addition, or alternately, control system82may include one or more sensors124(FIG. 6) that detect the height of the patient handling apparatus10. As noted above, suitable sensors may include Hall Effect sensors, proximity sensors, reed switches, optical sensors, ultrasonic sensors, liquid level sensors (such as available from MTS under the brand name TEMPOSONIC), linear variable displacement transformer (LVDT) sensors, or the like.

For example, in one embodiment, referring toFIG. 1A, an array of transducers T may be attached to the frame12, and a magnet M mounted, for example, to the foot-end upper pivot connections24b, including for example, to transverse member60forming or supporting the foot-end upper pivot connections24b(e.g.FIGS. 2 and 4). The array of transducers T may be mounted to frame12adjacent to or incorporated in guide32along path P, as partially shown inFIG. 1A. In this manner, as the foot-end upper pivot connections24bmove along path P magnet M will also move along the array of transducers, and the magnetic field of the magnet will be detected by one or more of transducers T to create an input signal or signals to the controller120that is indicative of the height position of the patient handling apparatus10.

Controller120, based on this signal or these signals, may control the hydraulic circuit90. For example, controller120may have a height value stored therein (in the controller's memory or a separate memory in communication with controller120) against which controller120compares the signal or signals. Based on whether the detected height (detected by the transducer or transducers) exceeds or is equal to or is less than the stored height value, controller120may be configured to control (e.g. open or close) valve116. For example, when operating in mode (3), where valve116is open to increase the speed of rod86, if controller120detects that the height of frame12is near or at (or exceeds) the stored height value, then controller may be configured to close valve116to no longer drive cylinder80at the increased speed, and either before, after, or while closing valve116may optionally slow or stop the pump. Further, as noted above, controller120may reverse the motor to avoid excess pressure in hydraulic circuit90. Alternately, controller120may optionally stop pump92in lieu of closing valve116.

In one embodiment, the stored height value may be less than the maximum height, and, therefore, controller120may be configured to close valve116before lift assembly reaches its maximum height. Additionally, as generally described above, controller120may be configured to slow or stop the pump to prevent overshoot. Further, on the other hand if the stored height value is the maximum height of lift assembly (e.g. the height at which pivot connections24breaches the position along the guide path as viewed inFIG. 1A)), then controller120may configured to also to stop pump92either before, after or at the same time controller closes valve116.

In this manner, when control system82does not detect that the base18is at a specified height, e.g. when the transducers do not yet detect the magnets that correspond to a specified height of the base18, control system82can operate cylinder at an increased speed but when it detects that the base18is near, at or exceeds the specified height, controller120may be configured to control hydraulic circuit90to slow or stop the extension of rod86of cylinder.

In another embodiment, control system82can operate cylinder80at an increased speed but when it detects that the base18is at a height approaching or near the specified height (e.g. before the base18reaches the ground or before lift assembly20reaches its maximum height or before reaching a prescribed configuration), controller120may be configured to control hydraulic circuit90to slow or stop the extension of rod86of cylinder, using any of the methods described above. That is either by controlling (e.g. closing) valve116, slowing or stopping the pump, or reversing the motor.

In yet another embodiment, control system82may include one or more sensors126(FIG. 6) that detect the configuration of the ambulance patient handling apparatus10. For example, similar to sensor124noted above, transducers (see above for list of suitable transducers or sensors) may be placed at different locations about the patient handling apparatus10that detect magnets also placed at different locations about the patient handling apparatus10. In this manner, when a magnet is aligned with the transducer (or one of the transducers), the magnet field will be detected by that transducer, which then generates a signal or signals that indicate that the patient handling apparatus10is in a defined configuration (associated with that transducer) of the patient handling apparatus10. The number of configurations may be varied—for example, a single sensor may be provided to detect a single configuration (e.g. fully raised configuration or a fully lowered configuration) or multiple sensors may be used to detect multiple configurations, with each transducer detecting a specific configuration. Again, the sensors create an appropriate input signal to the controller120that is indicative of the configuration of the patient handling apparatus10.

Further, when multiple configurations are detected, controller120may compare the detected configuration of patient handling apparatus10to a prescribed configuration and, in response, control the hydraulic circuit90based on whether the patient handling apparatus10is in or near a prescribed configuration or not. Or when only a single configuration is detected, controller120may simple use the signal from the sensor as an input signal and control hydraulic circuit90based on the input signal.

When the patient handling apparatus10is no longer in the prescribed configuration (e.g. by comparing the detected configuration to a prescribed configuration stored in memory or detecting that it is not in a prescribed configuration), controller120may be configured to open or reopen the valve116to allow cylinder80to operate at its increased speed but then close valve116when controller120detects that patient handling apparatus10is in a prescribed configuration and/or, further, may slow or stop the motor to stop the pump or reverse the motor.

For example, one of the prescribed configurations may be when the lift assembly is in its fully raised configuration. In this manner, similar to the previous embodiment, when controller120detects that patient handling apparatus10is near or in its fully raised configuration, controller120may be configured to close valve116so that cylinder80can no longer be driven at the increased speed, and further may also stop motor94to stop pump92. As noted above, controller120may open or close the valve116before, after, or at the same time as stopping the pump (or reversing the motor) based on the input signal or signals from or the status of the sensor(s). Alternately, controller120may stop the pump92in lieu of closing the valve116based on an input signal or signals from or the status of the sensor(s).

In yet another embodiment, the control system82may include a sensor128(FIG. 6), which is in communication with controller120, to detect when a load on the motor (or on the pump) occurs. For example, sensor128may detect current. In this manner, using sensor128, controller12can detect when the base is supported on a surface, such as the ground or the deck of the emergency vehicle, by detecting when the motor or pump encounter increased resistance, for example, by detecting the current in the motor. As would be understood, this increase resistance would occur when the base18is either supported or encounters an obstruction. Further, controller120may be configured to detect when the load has exceeded a prescribed value (e.g. by comparing the detected load to a store load value in memory), and optionally close valve116to no longer allow fluid communication between the rod end chamber84band the cap end chamber84avia conduit112when the load has exceeded the prescribed value. As noted above, controller120may open or close the valve116before the load reaches the prescribed value and further before, after, or at the same time as slowing or stopping the pump based on an input signal or signals from or the status of the sensor(s). As noted above, controller may also reverse the motor before, after or at the same time it closes valve116. Alternately, controller120may slow or stop the pump92in lieu of closing the valve116based on an input signal or signals from or the status of the sensor(s).

So for example, if an attendant is removing patient handling apparatus from an emergency vehicle and has selected the base lowering (or extending) function, and while the base is being lowered at the increased speed, controller120detects that the motor or pump is under an increase in load (e.g. detects an increase in current) (which, as noted, would occur when the base18is supported, either by a support surface or an obstruction) controller120may close valve116so that cylinder80will no longer be driven at the increased speed. Optionally, controller120may also or instead slow or stop the pump and/or stop the pump before closing the valve. Alternately, controller120may simultaneously close the valve116and slow or stop the pump. As described above, in yet another embodiment, controller120may close the valve116prior to base18being supported (for example, when the frame12or base18reaches a prescribed height or when apparatus10has a prescribed configuration) and only after controller120detects that base18has contacted the ground surface and/or the base18is fully lowered, controller120will stop pump92so that cylinder80will no longer extend. Or the controller120may be configured to stop the pump92before the base reaches the ground to avoid overshoot.

The controller120may also receive signals indicative of the presence of the patient handling apparatus10near an emergency vehicle. For example, a transducer may be mounted to the patient handling apparatus10, and a magnet may be mounted to the emergency vehicle and located so that when the patient handling apparatus is near the emergency vehicle, the transducer will detect the magnet and generate a signal based on its detection. In this manner, when an operator has selected the base extending (e.g. lowering) function and controller120detects that patient handling apparatus10is near an emergency vehicle and, further, detects one or more of the other conditions above (e.g. that the base is not contacting a support surface or there is no load on the motor or pump or the patient handling apparatus10is not in a prescribed configuration), controller120may open valve116to allow the cylinder to be driven at the increased speed. In this manner, these additional input signals may confirm that the situation is consistent with a mode 3 operation.

Alternately, controller120may also receive signals indicative of the presence of the patient handling apparatus10in an emergency vehicle. For example, a transducer may be mounted to the patient handling apparatus10, and a magnet may be mounted to the emergency vehicle and located so that when the patient handling apparatus is in the emergency vehicle, the transducer will detect the magnet and generate a signal based on its detection. In this manner, when an operator has selected the base lowering function and controller12detects that patient handling apparatus10is in the emergency vehicle and detects one or more of the other conditions above (e.g. that the base is not contacting a support surface or there is no load on the motor or pump or the patient handling apparatus10is not in a prescribed configuration), the signal indicating that patient handling apparatus10is in the emergency vehicle will override the detection of the other conditions and the controller120may maintain valve116closed to prevent the cylinder from being driven at the increased speed and, further, override the input signal generated by the operator.

In yet another embodiment, the patient handling apparatus10may include a patient handling apparatus-based communication system130(FIG. 6) for communicating with a loading and unloading based communication system132(FIG. 6) on a loading and unloading apparatus. For example, the communication systems130,132may be wireless, such as RF communication systems (including near-field communication systems). For example, the control system82may be operable to open or close the valve116based on a signal received from the loading and unloading based communication system132. In this manner, the deployment of the base of the patient handling apparatus10may be controlled by someone at the loading and unloading apparatus or someone controlling the loading and unloading apparatus.

In one embodiment, rather than allowing controller120to start in mode 3 (when all the conditions are satisfied), controller120may be configured initially start the base lowering function in mode 1, where the base is lowered at the slower, first speed. Only after controller120has checked that there is a change in the load (e.g. by checking a sensor, for example a load cell or current sensing sensor) on the motor or cot to confirm that the motor or pump are now under a load (which would occur once the apparatus is pulled from the emergency vehicle and the base is being lowered), does controller120then switch to mode 3 to operate the cylinder at the faster, second speed. Again, once operating in mode 3, should controller120detect one or more of the conditions noted above (base18is supported or encounters an obstruction, the height exceeds a prescribed height, the configuration is in a prescribed configuration, the load on the motor or pump exceeds a prescribed value) controller120will close valve116and optionally further slow or stop pump. As noted above, the valve116may be closed by controller120after the pump92is slowed or stopped or simultaneously.

In any of the above embodiments, it should be understood that control system82can control hydraulic circuit90to slow or stop the extension of rod86of cylinder, using any of the methods described above, before the conditions noted above, such as before reaching a predetermined height, before reaching a predetermined configuration, before making contact with the ground or an obstruction, or before reaching a prescribed load on the motor etc. Further, control of the fluid through the hydraulic circuit may be achieved by controlling the flow rate or opening or closing the flow using the various valves noted above that are shown and/or described. Further, as noted to avoid excess pressure in the hydraulic circuit, controller120may reverse the motor when controlling the valves described herein or may slow or stop the motor and pump before reaching the target (e.g. maximum height). Additionally, also as noted, controller120may control the hydraulic circuit by (1) adjusting the flow control valves or valves (e.g. valve116), (2) adjusting the pump92(slow down or stop) or 3) adjusting both the flow control valves or valves (e.g. valve116) and the pump, in any sequence.

Further, it should be understood, in each instance above, where it is described that the controller or sensor or other components are in communication, it should be understand that the communication may be achieved through hard wiring or via wireless communication. Further, although illustrated as discrete separate components, the various components may be assembled or integrated together into a single unit or multiple units.

As noted above, the frame12is optionally configured to allow the frame12to be tilted relative to the lift assembly20so that one end (e.g. head-end or foot-end) of the frame12can be raised beyond the fully raised height of the lift assembly to allow the patient handling apparatus to be inserted more easily into the compartment of an emergency vehicle. In addition, the frame12can be tilted without decoupling the frame12from the lift assembly20.

In the illustrated embodiment, movable foot-end upper pivot connections24bare configured so that they can move in a direction angled (e.g. oblique (acute or obtuse) or even perpendicular) relative to the longitudinal axis12bof the frame12and optionally along or relative to the longitudinal axis12b(FIG. 1) of the frame12. In this manner, the movable foot-end upper pivot connections24bfollow a non-linear path P that takes them toward or away from the longitudinal axis12bof the frame12over at least a portion of the range of motion of the movable foot-end upper pivot connections24bto cause the frame12to tilt relative to the lift assembly20(as opposed to being tilted by the lift assembly).

Referring toFIGS. 1 and 2, this range of motion where the frame12tilts may be at one end of the range of motion of the foot-end upper pivot connections24band, for example, where lift assembly20is raised to its maximum height or may be intermediate the ends of path P. Further, after lift assembly20has raised frame12to its maximum raised height (seeFIG. 2), frame12may be tilted further to raise the head-end of the frame12so that head-end wheel12acan be raised sufficiently to rest on the deck of an emergence vehicle compartment.

Referring again toFIG. 1, movable foot-end upper pivot connections24bare mounted to frame12by guides32. Guides32form a non-linear guide path P (FIGS. 1-5) (“non-linear path” means a path that does not form a straight line) for the movable foot-end upper pivot connections24b. While guide path P is non-linear, path P may include one or more linear sections and one or more non-linear sections, such as arcuate sections. In the illustrated embodiment, guides32provide a non-linear guide path P with one linear section that corresponds to the lowered height (FIG. 3) of the lift assembly20where movable foot-end upper pivot connections24bare at their lowest height and lift assembly20is in its folded, most compact configuration. The path P of each guide32also includes an arcuate section, which is the adjacent linear section and may have a single radius of curvature or two or more radii of curvatures. Further, the arcuate section may have two portions, with a first portion corresponding to the fully raised height of lift assembly20and a second portion corresponding to the fully raised height of lift assembly20, but with the frame12tilted further (FIG. 2).

Thus, when lift assembly20starts in its lowermost position and is extended, movable foot-end upper pivot connections24bmove along guide path P from one end (which corresponds to the lowermost position of lift assembly20) where the movement of movable foot-end upper pivot connections24bis generally linear (and parallel to longitudinal axis12bof frame12) to a non-linear portion of path P, which corresponds to a raised position of lift assembly. As lift assembly20continues to extend and raise frame12further, movable foot-end upper pivot connections24bcontinue to move along non-linear path P and initially move further away from longitudinal axis12b(while still moving relative or along longitudinal axis12b). During this movement, frame12remains substantially horizontal. As lift assembly20continues to extend to its fully raised position, movable foot-end upper pivot connections24bcontinue to move along the non-linear portion of path P and, further, continue to move away from longitudinal axis12b. This movement is then followed by movable foot-end upper pivot connections24bmoving toward longitudinal axis12bwhere frame12tilts upwardly (FIG. 1). It should be understood that the positions of load bearing members22and movable foot-end upper pivot connections24bare controlled and “locked” in their positions by the hydraulic cylinder. In order to further tilt frame12upwardly from its position shown inFIG. 1to its position shown inFIG. 2, a downward force is applied to the foot-end of the litter, which causes movable foot-end upper pivot connections24bto move toward the end of path P and move further towards longitudinal axis12b, which causes frame12to further tilt upwardly. Because the position of foot-end upper pivot connections24bis essentially locked in its position shown inFIG. 1, only an external force will cause upper pivot connections24bto move to the end of path P as shown inFIG. 2. As noted this external force may simply be manually applied by an attendant (e.g. an EMS person) at the foot-end of the litter—or it may be applied by an actuator.

As best seen inFIG. 6, foot-end upper pivot connections24bare supported on or formed by a transverse member60, which is mounted to the upper ends of telescoping members42by a rigid connection. In the illustrated embodiment, foot-end upper pivot connections24bare formed by the ends of transverse member60. For example, transverse member60may comprise a tubular member or solid bar with a circular cross-section. To accommodate the rotation of each telescoping member42(as lift assembly is extended or retracted) and allow each telescoping member42at the foot-end to pivot and translate along guide path P, foot-end upper pivot connections24boptionally each include a roller. The rollers are mounted about the respective ends of transverse member60and guided along guide paths P of guides32. For example, the rollers may each comprise a low friction collar, such as a high density polyethylene collar, or a bearing assembly, which is free to rotate about the end of tubular member and further, as noted, roll along guide path P. Alternately, foot-end upper pivot connections24bmay be configured to slide along path P.

In the illustrated embodiment, guides32are each formed from a low friction member or plate, such as a high density polyethylene plate, mounted to frame12. Each low friction member or plate72includes a recess formed therein, which forms guide path P. Alternately, guide32may be formed from a metal member or plate with the recess formed therein lined with a low friction material, such as high density polyethylene.

In this manner, pivot connections26ballows telescoping members42to pivot about a moving horizontal axis (i.e. moving horizontal axis of transverse member60) (moving both in the longitudinal direction and/or vertical direction, as noted above, namely along longitudinal axis12aor toward or away from longitudinal axis12a) and, further, allow lift assembly20to adjust the height of frame12relative to base18.

In addition, referring again toFIG. 2, frame12includes a pair of side frame members14aand14b, which are interconnected by cross- or transverse frame members36a(only one shown). Cross-frame member36aprovides a mounting point for the head-end load bearing members22of lift assembly20. In addition, side frame members14aand14bmay provide a mounting surface for collapsible side rails (not shown).

For further details of frame12, telescoping members44, base18, brackets54and56, linkage members50and52, and a gatch mechanism, and other structures not specifically mentioned or described herein, reference is made to U.S. Pat. Nos. 5,537,700 and 7,398,571, and published Application No. WO 2007/123571, commonly owned by Stryker Corporation, which are herein incorporated by reference in their entireties.

Thus, when the ambulance patient handling apparatus is in the fully collapsed position, and referring toFIG. 4, an extension of the linear actuator30will cause a clockwise (FIG. 4) rotation of the brackets54,56about the axis of fasteners55. Fasteners55secure the upper end of linkage members50,52to X-frames44. As a result of this geometry, the force in the direction of the extension of linear actuator30effects a rapid lifting of the frame12to the full height position of the lift assembly illustrated inFIGS. 1 and 2.

For further optional details on how lift assembly20is mounted to frame12, reference is made to copending provisional application entitled EMERGENCY COT WITH A LITTER HEIGHT ADJUSTMENT MECHANISM (Attorney Docket143667.173860(P566), Ser. No. 62/488,441) and filed on even date herewith, which is incorporated herein by reference in its entirety.

The terms “head-end” and “foot-end” used herein are location reference terms and are used broadly to refer to the location of the cot that is closer to the portion of the cot that supports a head of a person and the portion of the cot that supports the feet of a person, respectively, and should not be construed to mean the very ends or distal ends of the cot.

While several forms of the invention have been shown and described, other forms will now be apparent to those skilled in the art. For example, one or more of the features of the cot10may be incorporated into other cots. Similarly, other features form other cots may be incorporated into cot10. Examples of other cots that may incorporate one or more of the features described herein or which have features that may be incorporated herein are described in U.S. Pat. Nos. 7,100,224; 5,537,700; 6,701,545; 6,526,611; 6,389,623; and 4,767,148, and U.S. Publication Nos. 2005/0241063 and 2006/0075558, which are all incorporated by reference herein in their entireties. Therefore, it will be understood that the embodiments shown in the drawings and described above are merely for illustrative purposes, and are not intended to limit the scope of the invention which is defined by the claims which follow as interpreted under the principles of patent law including the doctrine of equivalents.