Patient support apparatus with lift assembly

Abstract

To improve a patient support apparatus with a lift assembly.SOLUTION: A patient support apparatus has: a frame supported relative to a floor, the frame configured to support a deck for supporting a patient thereon; and a lift assembly for raising or lowering the frame relative to the floor. The lift assembly has: lifting legs coupled to the frame; and an actuator with a body and an extendible member. The actuator is mounted to one of the legs, rather than the frame, and mounted for linear movement with respect to the one leg, with the linear movement translated into rotational movement of the other leg by a link and crank arm arrangement.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] This application claims the benefit of U.S. Provisional Application No. 62 / 948,540 (P-600), filed on December 16, 2019, entitled "Conforming Support with Lift Assembly", which is hereby incorporated by reference in its entirety.

Background Art

[0002] The present disclosure relates to a patient support device having a lift assembly for raising or lowering a patient support device deck relative to a floor surface. More specifically, the present disclosure relates to a patient support device having a lift assembly that can lower the deck of the patient support device to a very low height while providing a full range of motion to a height accessible to a caregiver for accessing a patient.

Summary of the Invention

[0003] A lift mechanism is described that is compact at a very low height while still providing a long travel to raise the deck of the patient support device to a height suitable for a caregiver. Additionally, the lift mechanism is configured to raise or lower one end of the patient support deck to orient the patient in the Trendelenburg position or the reverse Trendelenburg position.

[0004] In one form, the patient support device has a base and a frame supported with respect to the base, and the frame is configured to support a deck for supporting a patient thereon. The patient support device further has a lift assembly for raising or lowering the frame with respect to the base. The lift assembly has a first leg and a second leg, and the first leg is pivotally connected to the frame at its upper end and pivotally and slidably connected to the base at its lower end. The second leg is pivotally attached to the first leg at its central portion at its upper end so as to form an inverted Y-shaped leg assembly when deployed. The lift assembly further has an actuator mounted within the leg assembly in a mounting configuration that generates a maximum force F1 when raising the frame that occurs after the lift assembly has risen from its lowest configuration. For example, the maximum force F1 can occur at approximately the mid-stroke of the lift assembly.

[0005] In one embodiment, the actuator is mounted within the leg assembly in a mounting configuration that generates a starting force SF within the range of 95% to 99%, or 96% to 98%, or approximately 97% of the maximum force F1.

[0006] In one aspect, the actuator is mounted in a mounting configuration such that when raising or lowering the frame, it generates a minimum force F2 that is in the range of 50% to 70%, optionally approximately 60% of the maximum force F1.

[0007] In another embodiment, the patient support device has a base, a frame supported by the base and configured to support a deck for supporting a patient thereon, and a lift assembly for raising or lowering the frame relative to the base. The lift assembly is pivotally connected to the frame at its upper end and pivotally connected to the base at its lower end. The lift assembly has a first leg and a second leg, and the second leg is pivotally attached to the first leg at its central portion so as to form an inverted Y-shaped leg assembly when deployed. The actuator is mounted within the leg assembly in a mounting configuration to generate a maximum force F1 and a minimum force F2 when raising or lowering the frame, and the minimum force F2 is in the range of 55% to 65% of the maximum force F1. For example, the minimum force F2 may be generated at the maximum height of the lift assembly.

[0008] In one aspect, the actuator is mounted within the leg assembly in a mounting configuration to generate a starting force SF, and the minimum force F2 is within the range of 55% to 65% of the starting force SF.

[0009] In another embodiment, the patient support device has a base, a frame supported by the base and configured to support a deck for supporting a patient thereon, and a lift assembly for raising or lowering the frame relative to the base. The lift assembly is pivotally connected to the frame at its upper end and pivotally connected to the base at its lower end. The lift assembly has an actuator, a first leg and a second leg, and the second leg is pivotally attached to the first leg at its central portion so as to form an inverted Y-shaped leg assembly when deployed. The actuator is mounted within the leg assembly and is attached to the first leg by a first connection portion at one end and attached to the first leg by a second sliding pivot connection portion at its opposite end.

[0010] In one aspect, the second sliding pivot connection portion is connected to the second leg, and when the actuator expands and contracts, the first leg and the second leg are deployed or bent relative to each other.

[0011] In a further aspect, the first leg has an upper pivotal connection to the frame and a lower pivotal connection to the base, and further includes a drive link connected to the actuator at one end and connected to the first leg by a sliding link pivotal connection at the opposite end. The drive link is eccentrically connected to the second leg.

[0012] In one aspect, the sliding link pivotal connection between the drive link and the first leg includes a non-linear sliding pivotal connection.

[0013] In another aspect, the sliding link pivotal connection between the drive link and the first leg extends below the lower pivotal connection of the first leg when the lift assembly is in its lowest position.

[0014] In yet another embodiment, the patient support device has a base, a frame supported by the base and configured to support a deck for supporting a patient thereon, and a lift assembly for raising or lowering the frame relative to the base. The lift assembly is pivotally connected to the frame at its upper end and pivotally connected to the base at its lower end. The lift assembly has an actuator, a first leg and a second leg, and the second leg is pivotally attached to the first leg at its central portion so as to form an inverted Y-shaped leg assembly when deployed. The second leg has a crank arm. The lift assembly further has a drive link having a first end and a second end, the first end of the drive link being pivotally attached to the actuator, the second end of the drive link being connected to the crank arm and configured to move in a non-linear path, thereby being able to push or pull the crank arm within a certain angular range, thereby deploying or bending the first leg and the second leg relative to each other to contract or extend the lift assembly.

[0015] In one aspect, the first leg has an upper pivot connection to the frame and a lower pivot connection to the base, and the drive link is slidably connected to the first leg by a sliding pivot connection and is eccentrically connected to the crank arm.

[0016] In another aspect, the sliding pivot connection comprises a non-linear sliding pivot connection.

[0017] According to yet another embodiment, the patient support device has a base, a frame supported by the base and configured to support a deck for supporting a patient thereon, a head end actuator, and a foot end actuator. The patient support further has a lift assembly for raising or lowering the frame relative to the base, and this lift assembly has a head end leg assembly and a foot end leg assembly. Each of the leg assemblies has a pair of legs, and each pair of legs has a first leg and a second leg that forms an inverted Y-shaped configuration when raising the frame and is bent substantially flat when lowering the frame. The first leg is rotatably attached to the frame at its upper end and rotatably attached to the base at its lower end. Each pair of legs has a bending rotation axis, and each of the head end actuator and the foot end actuator has a first connection to its respective first leg and a sliding lower pivot connection to its respective first leg. The first leg and the second leg of each leg assembly are connected such that the leg assembly is deployed or bent by the extension and contraction of its respective actuator to raise or lower the frame.

[0018] In one aspect, each of the first legs is connected to its respective second leg by a drive link that is eccentrically attached to its respective second leg.

[0019] In a further aspect, one end of each of the plurality of drive links is connected to its respective first leg by a sliding pivot connection having an arcuate path.

[0020] In another aspect, the sliding and pivoting connection to the first leg of the actuator has a linear path.

[0021] According to another aspect, the head end leg assembly is independent of the foot end leg assembly.

[0022] In yet another embodiment, the lifting legs of the head end leg assembly are pivotally mounted at or near the head end pivot connection of the frame, and the lifting legs of the foot end leg assembly are pivotally mounted at or near the foot end pivot connection of the frame.

[0023] In a further aspect, the head end pivot connection and the foot end pivot connection are offset below the frame.

[0024] In another embodiment, the patient support device has a base, a support frame supported on the base and configured to support a deck for supporting a patient thereon, and a lift assembly. The lift assembly has a head end leg assembly and a foot end leg assembly. Each of the leg assemblies has an actuator and forms an independent assembly that can be attached between the base and the support frame as an assembled unit that only inserts a pivot connection between the leg assembly and the base and connects a pivot connection between the leg assembly and the support frame.

[0025] For example, in one aspect, the head end leg assembly and the foot end leg assembly each have an inverted Y shape when the lift assembly moves the support frame to the raised position.

[0026] In yet another aspect, at least one of the plurality of leg assemblies has first and second lifting legs. Optionally, the first lifting leg comprises an inverted U-shaped frame. Similarly, the second lifting leg may comprise a second inverted U-shaped frame. In another embodiment, one or both of the lifting legs may be L-shaped.

[0027] In another embodiment, the second lifting leg forms a stop for the first lifting leg when the lift assembly is bent to its lowest configuration.

[0028] According to yet another embodiment, the patient support device has a base, a frame supported by the base, a frame configured to support a cushion for supporting a patient thereon, and a lift assembly for raising or lowering the frame relative to the base. The lift assembly has a first lifting leg and a second lifting leg. A linear actuator is attached to the first lifting leg at one end and to the first lifting leg at the other end for linear movement of the first leg. The second lifting leg is connected to the actuator such that when the linear actuator extends or contracts, the second lifting leg is rotated about the first lifting leg.

[0029] In yet another aspect, the second lifting leg has a crank arm connected to the actuator by a link such that extension or contraction of the actuator induces rotation of the second lifting leg.

[0030] These and other objects, advantages and features of the present disclosure will be more fully understood and appreciated by reference to the description of the current embodiments and the drawings.

[0031] Before describing embodiments of the present disclosure in detail, it should be understood that the present disclosure is not limited to the details of operation, or details of construction and arrangement of components, described in the following description or illustrated in the drawings. The present disclosure can be implemented in various embodiments and can be carried out or implemented in alternative ways not explicitly disclosed herein. Further, it should be understood that the expressions and terms used herein are for purposes of description and should not be regarded as limiting. The use of the terms "including" and "comprising" and their variants means including the items listed hereinafter and their equivalents, as well as additional items and their equivalents. Further, enumeration may be used in the description of various embodiments. Unless otherwise specified, the use of this enumeration should not be construed as limiting the present disclosure to any particular order or number of components. Also, the use of enumeration should not be construed as excluding from the scope of the present disclosure any additional steps or components that can be combined with or are combinable with the listed steps or components.

Brief Description of the Drawings

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DETAILED DESCRIPTION OF THE INVENTION

[0033] Referring to FIG. 1, reference numeral 10 generally indicates a patient support device. In the illustrated embodiment, the patient support device 10 is configured as a bed, such as a hospital bed, having a headboard 10a, a footboard 10b, side rails (not shown), and an articulated deck 16. However, it should be understood that the patient support device 10 can take other forms, including stretchers, foldable beds, etc. Generally, the patient support device 10 is used whenever a patient is to be supported and it is desirable to raise and lower the patient relative to the floor or other support surface. As will be described below, the patient support device 10 is a lift assembly for raising or lowering a patient support device surface, such as a mattress or other cushioning device, on which the patient is supported, between a fully raised position and a lowest position, and has a lift assembly that leaves sufficient clearance for an overbed table or a base on a patient lift to extend under the patient support device.

[0034] As best shown in FIG. 2, the patient support device 10 includes a base 12, a support frame 14 for supporting the deck 16 (FIG. 1), and a lift assembly 18 for raising or lowering the support frame 14 (and the deck 16, see FIG. 1) relative to the base 12. The frame 14 can also support a load frame that is below the deck 16, and it should be understood that this load frame is used to attach sensors such as load cells to measure the weight of a patient supported on the deck. However, there may be cases where the load frame is not required. Instead, for a reduction in force, particularly a reduction in torque on the frame 14, a load cell can be placed within the frame 14, which is achieved by the arrangement of the components of the lift assembly, which will be more fully described later.

[0035] As best shown in FIG. 2, the base 12 is a wheeled base with a plurality of caster wheels 15 to facilitate movement of the bed across the floor. In the illustrated embodiment, referring again to FIG. 1, the deck 16 has a plurality of articulated deck portions 16a, 16b, 16c, 16d, and 16e. However, it should be understood that the number of deck portions may vary. For example, each deck portion can be articulated and connected by an actuator (not shown) to raise or lower the deck portions so that the deck portions are oriented in a flat configuration or a chair configuration (and various other configurations therebetween). The structure of any of the base 12, the support frame 14, the headboard 10a, the footboard 10b, and / or the side rails can be any known design, such as, for example, U.S. Patent No. 7,690,059 issued to Lemire et al. of the same applicant, titled "Hospital Bed," the entire disclosure of which is incorporated herein by reference in its entirety, or U.S. Patent No. 8,689,376 of Stryker Corporation of the same applicant, titled "Patient Handling Device," having a local status display, one-touch Fowler angle adjustment, and a power-on alarm configuration, the entire disclosure of which is incorporated herein by reference in its entirety. The structure of any of the base 12, the support frame 14, the headboard 10a, the footboard 10b, and / or the side rails can take a form different from those disclosed in the aforementioned patents and patent publications.

[0036] As will be further fully described below, the lift assembly 18 can use an actuator having a shorter stroke and a consistent force limit ("the ability of the actuator to be less than the applied force"), and can lower the deck to a low height position such as 28 cm (11 inches) away from the floor, and to full height positions such as in the range of 66 cm (26 inches) to 86 cm (34 inches) away from the floor. In other words, by better optimizing the force curve, the same energy can be applied. In this way, the maximum lower load, such as welds forming the leg assembly, can be applied to the components. Further, this reduces costs and allows for the use of a lighter actuator.

[0037] Optionally, the actuator can be mounted so as to reduce, if not eliminate, any lateral load on the lifting legs by providing sufficient play in the actuator mounting arrangement and not creating enough play to induce a lateral load at the rod mounting position. Further, as described above, the actuator is not mounted to the frame. Instead, as will be described below, the actuator is fully housed and mounted within the leg assembly, thereby reducing the force on the frame and, as a result, allowing a load cell to be mounted to the frame to measure the patient's weight, as well as movement and the patient's biometrics.

[0038] In addition, when the lift assembly 18 is moved to its lowest configuration as shown in FIGS. 4 and 8, the lift assembly 18 can be substantially housed within the base 12 without interfering with a central space S below the base that may be required to attach a control device for drive wheels and a wheel drive system (such as the Zoom system sold by Striker). Thus, for example, when lowered, the patient support device 10 can be configured such that the central space S below the base is empty over a length S1 of at least about 46 cm (about 18 inches). In this way, the patient support device 10 can provide a very low-profile patient support device, thereby reducing the chance of a patient falling without eliminating the available space below the base.

[0039] Referring again to FIG. 2, the lift assembly 18 has a head end lift assembly 18a and a foot end lift assembly 18b, which assemblies can be substantially mirror images of each other and can be attached adjacent to the respective head end and foot end of the frame 14. For ease of explanation, much of the following details are made with reference to the head end lift assembly 18a, but it should be understood that similar details apply to the illustrated foot end lift assembly 18b, which is shown as a mirror image and is numbered with the same number as the head end lift assembly. However, it should be understood that the head end lift assembly and the foot end lift assembly may have different configurations.

[0040] As best shown in FIG. 1A, the frame 14 has a pair of longitudinal frame members 14a and a pair of transverse frame members 14b that connect the longitudinal frame members 14a to form the frame. Referring to FIGS. 2, 2A, 3, 3A, 4, and 4A, the head end drift assembly 18a has a first lifting leg 20 and a second lifting leg 22, which are pivotally joined by a pivot connection 30 (best seen in FIG. 3A) to form a folding leg assembly 21. The pivot connection 30 is formed by a pin 30a (FIG. 9F) that pivotally joins the first lifting leg 20 and the second lifting leg 22 through openings 30b, 30c (see FIGS. 12A and 12C) formed in the respective legs 20, 22.

[0041] The first lifting leg 20 is pivotally attached to the support frame 14 at its upper end at a pivot connection 24 (FIG. 1A) formed by a pair of pins that are pivotally attached to the frame 14 by a pivot block 14d or the like. These pivot blocks 14d are attached to the transverse frame member 14b of the frame 14 via brackets 14c. Optionally, the pivot connection 24 can be formed by a single pivot rod 24a (shown in phantom in FIG. 2A) that extends transversely below the upper transverse frame member 44 (described later) and extends to the upper end of the leg 20 and passes through the pivot block 14d. This pivot rod telescopically enters the upper end of the leg 20 when the lift assembly is lowered and folded. Optionally, the rod 26a can be supported by an intermediate bracket 24b (FIG. 2A) attached to the lower surface of the frame member 44.

[0042] The lifting legs 20 are pivotally attached to the base 12 at their lower ends at the sliding pivot connection 26, as by a pivot block 60 (more fully described below). The second lifting leg 22 is pivotally attached to the base 12 at its lower end at the pivot connection 28 and is pivotally attached to the central portion of the lifting leg 20 at the pivot connection 30 adjacent its upper end. In this way, when the legs 20 and 22 are deployed about the pivot connection 30, the legs 20 and 22 form an inverted Y-shaped frame and, when folded, the legs 20 and 22 are disposed in a generally flat configuration (see FIG. 4). Further, as more fully described below, when the legs 20 and 22 are folded, the legs 20 and 22 can be disposed within the base 12 such that the deck 16 drops to a height H of less than 30 cm (12 inches) from the surface on which the base is supported. Optionally, also, as more fully described below, the second lifting leg 22, when folded, provides a contact surface in the form of, for example, a stop 22a (see FIG. 1) for the lifting leg 20 such that the load on the frame and deck can be directly transmitted to the base 12 via the pivot connections 26 and 28.

[0043] As will be described more fully below, the lift assembly 18a (and lift assembly 18b) has an actuator 36 in the form of a linear actuator such as a pneumatic, electric or hydraulic actuator. As will be described more fully below, the upper end portion of the head end actuator 36 (fixed base 36d, see, for example, FIGS. 2A and 3) is attached to the upper end portion of the first lifting leg 20 by, for example, a pivot connection 37a and a bracket 37b, and further attached to the first lifting leg 20 at its opposite end via a sliding pivot connection 37c. In this way, when the extendable rod 36a extends, the extendable rod 36a is extended along an axis 36b that is fixed relative to the first lifting leg 20 (further details will be described later). In other words, the actuator does not pivot relative to the first lifting leg 20, but instead selectively extends generally parallel to the lifting leg 20 (see, for example, the details of the selective structure of the first lifting leg 20, referring to at least the upper linear portion of the leg 20, which will be described later).

[0044] To convert the linear motion of the actuator 36 into the rotational motion of the second lifting leg 22 (and thus the upward motion of the lift assembly 18a), the lifting leg 22 is connected to the actuator via a link and crank arm arrangement. Further, as will be described more fully below, the link and crank arrangement can be configured to adjust the force curve of the lift assembly to closely match the allowable force of the actuator.

[0045] For example, in one embodiment, the actuator, link, and crank arm arrangement within the lift assembly is configured to generate a maximum force F1 that occurs when the frame 14 is lifted after the lift assembly 18 has risen from its lowest configuration. Referring to FIG. 9H, the maximum force F1 can occur at approximately the mid-stroke of the lift assembly. Further, the actuator, link, and crank arm are attached in a mounting configuration that generates a starting force SF within the range of 95% - 99%, 96% - 98%, or about 97% of the maximum force F1 within the leg assembly 21 (see FIG. 9H). As a result, the actuator can have a shorter stroke size than would normally be used and can have a consistent force limit that varies from about 1500 Newtons to about 3000 Newtons (see FIG. 9H).

[0046] Further, by doing so, the speed of the deck's ascent is more uniform over its entire range of motion, which is more comfortable for the patient supported thereon. For example, the speed of the actuator over its entire range of motion can be more consistent and can be in the range of about 0.7 - 1.3 distance / time. It should be understood that this speed varies depending on the weight of the patient supported thereon and the capabilities of the selected actuator.

[0047] In the illustrated embodiment, and referring to FIGS. 9A-9G, the second lifting leg 22 is connected to the actuator 36 via a pair of crank arms 32 and via links 38, 40. Each crank arm 32 is fixedly attached to the second lifting arm 22 at its upper end and is pivotally connected to its respective link 40 by a pivot connection 32a at its lower end. Next, each link 40 is pivotally connected to link 38 via a pivot connection 40a. In addition, link 38 is pinned to the actuator 36 at its opposite end via a transverse pin 36c attached to the distal end of the rod 36a of the actuator 36. Thus, the distal end of link 38 is extended along axis 36b when the rod 36a extends or contracts along axis 36b. In addition, the pin 36c and the distal end of link 38 move within a linear path P1 described more fully hereinafter. Optionally, the distal end of link 38 may have a slotted opening 38a formed therein to receive the pin 36c to help relieve the actuator of force at a low height, as described more fully hereinafter with reference to stop 22a.

[0048] As best seen in FIGS. 9A - 9C, link 38 extends rearwardly from pin 36c towards the fixed base 36d of actuator 36. Further, link 38 forms an acute angle with rod 36a throughout its entire range of motion and its distal end moves along path P1, as will be described later. The opposite proximal end of link 38 is guided along a non - linear path P2 (see FIGS. 9E - 9G and 1A) that branches away from the linear path P1 of pin 36c, at least initially (at pivot connection 40a), in other words away from axis 36b. As described above, the rod 36a of the actuator extends along axis 36b which is fixed to and substantially parallel to at least the linear portion of the lifting leg 20. Thus, when rod 36a is extended, link 38 becomes a tension - driving link that pulls pin 40a’ of pivot connection 40a along path P2 and pushes pivot link 40. Link 40 pushes crank arm 32, applies a moment to the second lift leg 22, rotates the second lift leg 22 counter - clockwise (as seen in FIG. 9A) about pivot connection 30, and deploys the leg assembly 21 until 40a’ of pivot connection 40a reaches the end of path P2. Conversely, as will be understood, when rod 36a is contracted, link 38 becomes a compression - driving link that pushes pin 40a’ along path P2 (towards the fixed base 36d of actuator 36) and pulls link 40. Next, link 40 pulls crank arm 32, applies a moment to the second lift leg 22, rotates the second lift leg 22 clockwise (as seen in FIG. 9E) about pivot connection 30, and bends the leg assembly 21 until the pin connection 40a reaches the other end of path P2. As will be understood, path P2 can extend beyond the path of pivot connection 40a and as a result, the ends of the path of pivot connection 40a are defined by actuator 36 rather than hard stops on both ends of path P2.

[0049] To hold the rod 36a of the actuator 36 along its fixed linear path, the first lifting arm 20 has a track 42 extending therefrom along the axis 36b, and this track 42 guides the rod 36a of the actuator 36 when it extends or contracts. In the illustrated embodiment, the track 42 forms a pair of opposing plates 48, such as a press-worked plate, and has an elongated slot 48a for guiding the pin 36c of the rod 36 along its linear path P1 along the axis 36b. Optionally, as will be more fully described below, the plate 48 can be configured to provide a contact surface 48b along the edge of the slot 48a for the pin 36c to reduce slop and play and provide a tighter assembly. For example, the contact surface 48b can be provided by a lip formed in the plate 48 along at least the lower edge of the slot 48a, but can extend around the entire perimeter of the slot to reinforce the plate at the slot location.

[0050] In the illustrated embodiment, referring to FIG. 9A, the first lifting leg 20 is formed from an inverted U-shaped frame including an upper cross-frame member 44 and two vertical frame members 46, and these frame members are joined to each other by welding or the like. The actuator 36 is attached to the lifting leg 20 between the plurality of frame members 46 with its upper end attached to the cross-frame member 44 by a pivot connection 37a. The pivot connection 37a can be formed by a bracket 37b, such as a pair of plate brackets attached to the cross-frame member 44 by welding, for example.

[0051] (As noted, the track 42 that guides the extension of the rod end 36a along the axis 36b) extends from the upper cross-frame member 44 and is supported and rigidly attached (e.g., by welding) at one end to the cross-frame member 44 (see FIGS. 9A and 2A). The track 42 is also supported and attached to the second cross-frame member 50. The cross-frame member 50 is spaced from the cross-frame member 44 and is rigidly attached (e.g., by welding) between the frame members 46 to provide support to the track 42 and, in addition, to provide rigidity to the frame members 46.

[0052] In the illustrated embodiment, the second lifting leg 22 can also be formed from an inverted U-shaped frame comprising an upper cross-member 56 and two vertical frame members 58 joined to each other (e.g., by welding). The plurality of frame members 58 straddle the frame members 46 of the first lifting leg 20 and are each rotatably attached thereto by a pivot connection 30. The cross-frame member 56 is rigidly attached (e.g., by welding) to the cross-frame member 56 and supports and provides a mount for the crank arm 32 that straddles the track 42.

[0053] As best shown in FIGS. 9A-9G, each plate 48 forming the track 42 is supported and attached (e.g., by welding) to the cross-member 44 and the cross-member 50. In the illustrated embodiment, the cross-member 50 passes through the opening 48c formed in the plate 48 and is welded to the plate 48 around the opening 48c sized to fit the cross-member 50. Similarly, the upper end of the plate 48 has a notch 48d (FIG. 12B) sized to receive the cross-member 44 and the cross-member 44 can be welded to the respective plate 48 around the respective notch. Optionally, the ends of the plate 48 can extend to form the bracket 37b.

[0054] Path P2 can also be formed by a pair of slots 48e to guide the pivot connection portion 40a. The slots 48e can also be formed in the plate 48 and have a contact surface 48f for the pin 40a' of the pivot connection portion 40a, thereby reducing sag and thus increasing the tightness of the movement of the lift assembly. Similar to the contact surface 48b, the contact surface 48f can be provided by a lip formed in the plate 48 along at least the lower edge of the slot 48e, which can extend around the entire circumference of the slot 48e to reinforce the plate 48 at the slot position.

[0055] As best shown in FIG. 9E, the lips forming the contact surfaces 48b and 48f can extend in opposite directions from each other, i.e., the contact surface 48b is formed on a lip extending from the inside of the plate 48, and the contact surface 48f is formed on a lip extending from the outside of the plate 48.

[0056] To guide the pivot connection portion 40a and the link 38, and thus the crank arm 32, along a desired path, each slot 48e can be non-linear. Each slot 48e has a first curved portion that is approximately located at the distal end of the slot 48e closest to the end of the rod 36. The first curved portion forms a part of path P2 that first branches away from path P1 (and thus away from axis 36b). The second portion of the slot 48e can be linear but angled upwardly towards axis 36b and extends from the first curved portion towards the proximal end of the slot 48e (the end closest to the fixed body 36c of the actuator 36).

[0057] In this way, when the rod 36a is fully extended, the leg assembly 21 is fully raised, and then the actuator 36 is contracted, the link 38, which now acts as a compression link, pushes the pivot connection portion 40a along the first curved portion of the path P2, thereby pulling the link 40 and pulling the crank arm 32 while increasing the angle between the link 40 and each crank arm 32. Due to the branch angle of the path P2 from the path P1, which increases the leverage action of these levers on the crank arm 32, the above-mentioned angle increases when the pivot connection portion 40a moves along the curved portion. As the rod 36a continues to contract, the pivot connection portion 40a continues to move along the path P2, and the link 40 and the crank arm 32 increase their angular separation. This increase in angular separation increases the leverage action of the link 40 and bends the leg completely, pulling the crank arm 32 until the link 40 reaches the lowest position where it can exert the maximum leverage action. At the lowest position, this is usually the point where the maximum torque is required, usually due to the maximum separation of the pivot connections 26, 28. However, in the current configuration, at this point, the force required by the actuator 36 to move the second leg 22 is not the maximum. Instead, when they are in their orientations corresponding to the lowest position of the lift assembly 18a, it is smaller than the maximum force resulting from the increased leverage action of the link 40. Therefore, the shape of the path P2 is such that, usually, when the leg assembly 21 is at the lowest height where the pivot connections 26, 28 of the first leg 20 and the second leg 22 are furthest apart, the maximum leverage action occurs at the point where the maximum force is usually required to lift the leg assembly. However, here, as described above, due to the increase in the leverage action of the link 40 on the crank arm 32, the required force is not the maximum force. Instead, the maximum force is required when the leg assembly 21 is lifted partway up, where the pivot connections 26, 28 of the first and second legs are still significantly apart, but the link 40 reduces the leverage action on the crank arm 32.

[0058] In other words, when the leg assembly 21 has fully descended (see FIGS. 9G and 8A) and the pivot connection 40a is at the proximal end of path P2, the link 40 is substantially perpendicular to the crank arm 32 and thus, as described above, has the maximum lever action. Additionally, as described above, as the lever action increases, the amount of force is less than the maximum force required to raise or lower the leg assembly 21. However, as the rod 36 is extended, the leg assembly moves from the lowest position to a central position where the pivot connection 40a reaches the greatest distance from path P1 (or axis 36b), corresponding to a position where the link 40 forms an acute angle and thus is angled closer to the crank arm 32, and the force required by the actuator increases. In this orientation, the link 40 has a smaller lever action than when it is in the lowest position. However, as the rod continues to extend, the pivot connections 26, 28 of the first leg and the second leg are brought closer together to reduce the amount of torque required for the continuous deployment of the first leg 20 and the second leg 22, and as they approach the distal end of path P2, the reduced lever action of the link 40 becomes consistent with the reduction in the amount of torque required to move the second leg 22 closer to the fully raised height of the leg assembly 21. As a result, referring to FIG. 9H, the force limit of the actuator is reduced.

[0059] Although described as a sliding pivot connection, the pivot connection 40a can be formed from a single pin or rod 40a' extending between the link 40 and the plate 48.

[0060] Optionally, to provide additional support to the track 42, the crank arm 32 can be rotatably connected to the track 42 by a pin or rod 58a passing through an opening flange 48g (FIGS. 9B and 12A) extending upward from the plate 48.

[0061] In the illustrated embodiment, to increase the rigidity and torsional resistance of the lifting legs 20, 22, each frame member forming each lifting leg can be formed from one or more closed cross-sectional members, such as formed from a metal such as steel. Alternatively, each lifting leg 20, 22 can be formed from a solid member such as a steel bar or plate. Similarly, the transverse frame members 50 and 56 are also formed from tubular members, extend into one or more transverse openings formed in the respective legs 20, 22, and are welded therein around one or both of the openings, thereby forming a rigid frame.

[0062] For example, the vertical members 46 and 58 can be formed from a closed tubular member or a solid plate. The closed tubular member can be formed from two structural channel members or pressed plates that are joined together, for example, by welding. For example, each plate can be pressed into a channel-shaped cross-section and then joined together in an opposing relationship (such that the open sides face each other, like a clam shell arrangement). Optionally, the two plates can be slightly nested such that the flange of one channel-shaped member is inserted into the opening face of the other channel-shaped plate and then welded in place by spot welding or continuous welding along their lengths. Alternatively, the plates can be dimensioned such that their flanges abut each other and are welded together, for example, by spot welding or continuous welding along their lengths.

[0063] In addition to increasing the strength and torsional resistance of the lifting legs, the structure allows the shape of the legs to be adjusted. For example, instead of having to have a relatively long pin 26b on the pivot connection 26 that extends into the space between the leg 20 and the base (12), as seen in FIG. 9A, the lower portion of the leg 20 (e.g., the vertical member 46) can be formed so that they are offset or angled outwardly. For example, starting from below the pivot connection 30, the lower portion of the leg 20 (e.g., the vertical member 46) can be formed such that they are offset or angled outwardly so that the mount 26a for the pivot connection 26 on the leg 20 is offset outwardly and can be aligned in the same plane as the mount 28a for the pivot connection 28. In this way, the pivot connections 26 and 28 can be mounted within the same channel (channel 12c of the frame member 12a). Thus, a single tube weldment can be used to form the base 12.

[0064] On the other hand, the cross member 44 can be formed from an open segmented member such as a channel-shaped member having a channel formed from a pressed plate or a structural channel member.

[0065] The track 42 can be formed from a plate that can be reinforced with the brace 48h as described above (FIG. 9A). Similarly, the links 38, 40 and the crank arm 32 can also be formed from plates and, if necessary, embossments or bosses can be provided around their mounting openings to increase their strength. For example, referring to FIG. 12E, each link 40 can be formed from an elongated rectangular plate having an embossment 40b to reinforce the plate. Similarly, the crank arm 32 (FIG. 12C) can be formed from a substantially triangular plate and can have an embossment 32b to reinforce the crank arm.

[0066] Referring to FIG. 12B, the plurality of links 38 are formed from two plates 38b joined by a transverse plate 38c at their (e.g., lower) edges, which can be welded to the plates 38b or formed by the plates 38b to form a U-shaped link assembly. The opening 38a can be reinforced by a boss or lip 38a' that surrounds the peripheral opening 38a and also forms a contact surface for the pin 36c of the actuator 36. As described above, the opening 38a can also be elongated to allow for load relief from the actuator 36, for example when the lift assembly 18a is fully lowered.

[0067] Furthermore, as shown in the illustrated embodiment, the cross-sections of some components of the lift assembly can vary along their lengths to provide increased strength as needed, but are reduced in cross-sections where the load on the lift assembly is reduced, thereby providing a more compact and lightweight assembly. Additionally, by varying the cross-sections, the components of the lift assembly can provide a better nested arrangement when folded. In the illustrated embodiment, the frame member 46 is formed with three different cross-sections in three different elevations, whereby the lifting leg 20 can avoid interference with other components of the bed, including the leg 22, as it swings throughout its entire range of motion.

[0068] For example, referring to FIG. 9A, the upper end portion of the leg 20, e.g., the vertical frame member 46, may have a maximum cross-section on the condition that the force for raising or lowering the frame 14 is maximum at the upper end portion of the leg 20. Further, as the cross-section increases, a portion of the frame member 46 may provide a path for the cable passing through the lift assembly, and further, may have an open portion at their upper end portions to provide a better nesting. As best understood from FIG. 1A, when the lift assembly is fully folded to lower the frame 14, the mounting brackets 14c and the mounting blocks 14d can extend into and nest within the open portions of the side portions of the frame member 46, which again aids in reducing the overall height of the deck when the lift assembly is in its lowest configuration.

[0069] As described above, the lower end portions of the lifting legs 20, 22 are attached to the base 12 by the pivot connections 26, 28. As seen in FIG. 9, the pivot connection 26 can be formed by a sliding block 60 rotatably attached to each of the lower end portions of the lifting leg 20 by a plurality of pins 26b. The plurality of blocks 60 are guided within a channel 12c formed in the base frame member 12a (FIGS. 2 and 4) between the upper flange and the lower flange 12b. Similarly, the pivot connection 28 can be formed by a block 64 rotatably attached to each of the lower end portions of the lifting leg 20 by a pin 28b. The block 64 is positioned and fixed within the channel 12c by a fastener 65 extending through an opening in the upper flange 12c of the frame member 12a.

[0070] To make the lift assembly more compact, blocks 60 and 64 can be attached to pins 26b, 28b using tab and slot arrangements having blocks 60 and 64, respectively, as described below with reference to FIGS. 10, 10A, 10B and 10C, without using fasteners or spring clips, and can alternatively be held on pins 26b and 28b. Also, to prevent blocks 60, 64 from rotating and disengaging from pins 26b, 28b, each block has a tabbed connection for attaching pins 26b, 28b to the block. Each pin 26b, 28b has one or more tabs that must be aligned with corresponding notches provided in block mounting openings 60b, 64b to attach the block or remove the block from the pin. Further, referring to FIGS. 3 and 10, each mounting block is square or rectangular, whereby pins 26b and 28b rotate freely within the block but can be held and do not rotate between the upper flange and lower flange 12b of frame member 12a. The tabs (and corresponding notches) on the pins are arranged so that they are not aligned during normal movement of the lift mechanism, and thus hold the respective blocks on pins (26b 28b) during normal operation.

[0071] As best seen in FIGS. 10A and 10B, block 60 has a rectangular body 60a with a central transverse opening 60b having one or more notches 60c. In the illustrated embodiment, opening 60b has a pair of opposing notches. Similarly, pin 26b has one or more tabs 26c for alignment with the notches. When so aligned, pin 26b can be inserted into opening 60b of block 60, and then block 60 can be rotated about the pin, thereby holding the pin on the block. The block is then placed within insertion frame member 12a (via cutout or notch 12e described below) and captured between the upper and lower flanges. Optionally, the upper and lower flanges can have lips 12b' (FIGS. 10 and 10A) extending downwardly and upwardly, respectively, to further assist in holding blocks 60 and 64 within channel 12c.

[0072] As best shown in FIG. 10C, block 64 similarly has a rectangular body 64a with a central transverse opening 64b having one or more notches 64c. In the illustrated embodiment, opening 64b has a pair of opposing notches 64c. Similarly, pin 28b has one or more tabs 28c for alignment with the notches. When so aligned, pin 28b is inserted into opening 64b of block 64, and then block 64 can be rotated about the pin, thereby holding the pin on the block. The block is then inserted into frame member 12a (via cutout or notch 12e described below) and captured between upper flange and lower flange 12b. To fix block 64 in a fixed position, block 64 has a transverse opening through body 64a and an offset portion 64d that is curved and aligned with the transverse opening for receiving fastener 65 through body 64a, thereby fixing the position of pivot connection 28 along frame member 12a of base 12.

[0073] Referring to FIGS. 3 and 10, blocks 60 and 64 are inserted into channel 12c of frame member 12a through cutouts 12e formed in the upper flange of frame member 12a. The plurality of cutouts 12e are disposed offset from the pivot connection portion 28. When installed, they are fixed via fasteners 65 along the longitudinal axis of frame member 12a, deviating from the normal movement of the sliding pivot connection portion 26. When blocks 60 and 64 are inserted therein, they are moved to their use positions and then held therein by the upper and lower flanges 12b and the optional lip 12b' of frame member 12a. Thus, base 12 has a plurality of installation positions for the pivot connection portion offset from its use position.

[0074] In addition to the overall structure, this installation arrangement and mounting configuration enable the lift assemblies 18a (and 18b) to be installed as a unit (already assembled within the unit and having actuators and lines (e.g., power and / or hydraulic lines and / or pneumatic lines)), simply by inserting the lift assembly into the base and connecting it to the mounting block 14d at its upper end, without the need for additional brackets and fasteners for attachment.

[0075] Further referring to FIGS. 1C and 4 again, when frame 14 is in its lowest position, frame member 14a of frame 14 abuts on base 12, i.e., it can abut between a plurality of base members 12a. Further, the lifting legs 20, 22 and the crank arms 32 are bent within the space defined between a plurality of base members 12a, and most of them are arranged such that most, if not all, of the legs 20 and the actuators 36 are above or below the upper flange of the base member 12a (FIG. 8). Further, as described above, the pivot connection portions 26 and 28 are aligned along their respective base frame members 12a and are in the same plane, and the plurality of pivot connection portions 30 are aligned on or immediately below the upper flange of their respective frame members 12a.

[0076] Thus, when the lift assembly 18 is in its lowest configuration, many of the components of the lift assembly (lifting legs, crank arms) are lowered into the space defined between or slightly below the plurality of base frame members 12a, as described above, but the space S is left between. Further, when the lift assembly 18 is in its lowest configuration, the distance from the top of the deck to the floor is less than 36 cm (14 inches), less than 33 cm (13 inches), and optionally, less than 30 cm (12 inches). Further, the space below the base member 12a is sufficient to allow an overbed table or the base of the lift assembly to extend below the base. For example, the distance from the lower surface of the base member 12a to the floor is at least 10.2 cm (4 inches), at least 12.7 cm (5 inches), or about 12.7 cm (5 inches) to 15.2 cm (6 inches).

[0077] As described above, the second lifting leg 22 has one or more stop portions 22a for providing a stop for the upper portion of the leg 20 when the leg assembly 21 is fully folded. The stop portion 22a is attached and arranged to extend inwardly of the leg 22 so as to provide a support surface for the vertical frame member 46 of the first lifting leg 20 when the first lifting leg 20 is fully folded.

[0078] In the illustrated embodiment, the stop portion 22a is formed by an L-shaped bracket 22b attached to the inner surface 22c of the lifting leg 22, such as by welding. The bracket 22b extends inwardly from the side surface 22d facing inwardly of the leg 22 so as to contact the side surface facing downward of the leg 20 when the leg 20 is folded. The bracket 22b has a rubber bumper 22c (FIG. 11) attached thereto, which can reduce noise and absorb a certain amount of vibration. Since the stop portion is disposed adjacent to the pivot connection portion 28, when folded, the weight of the deck and the frame essentially passes directly through the leg 22 to the base 12.

[0079] Referring to FIG. 9A, as described above, the actuator 36 can be attached to reduce the lateral load on the components of the lift assembly. For example, the pin 36c of the actuator 36 can be attached within the slot 48a of the plate 48 between a plurality of links 38 and between a pair of bushes 37e (FIG. 9D). Optionally, a gap or space is provided between a plurality of bushes 37e, for example between a plastic bush and the rod 36a (or between the bush and the link 48), providing sufficient play to avoid connection, but also providing a play small enough to avoid inducing lateral loads on, for example, the lift assembly, more specifically on the track 42 (to avoid the actuator from angling with respect to the path P1). For example, the gap on both sides can fall within the range of 12.7 mm (1 / 2 inch) to 25.4 μm (1 / 1000 inch). Further, to help hold the pins within the slot 48a, the respective opposing ends of the pins 36c can be guided by rectangular bushes 37f that are higher than the height of the slot 48a such that they ride on the outer surface of the plate 48. Optionally, a spring can be provided instead of or in addition to the bushes 37e to help maintain the alignment of the rod 36a along the path P1.

[0080] Referring to FIGS. 1A and 3, optionally, one or more of the components of the lift assembly can have a protective and / or aesthetic cover, for example formed from plastic. For example, covers C1 and C2 can be provided to cover and optionally protect the head end and the foot end of the base 12. Similarly, at least the rod and the track of the actuator can be covered by the cover C3. The cover C4 can also be provided to extend across the leg 22. However, it should be understood that many of the components of the lift assembly are of a closed structure and there is no need to provide a cover for the leg assembly of the lift assembly.

[0081] Although not specifically described in each example, it should be understood that all of the structural load-bearing members of the lift assembly can be formed from a metal containing steel, and further, as press-working members, forming members, casting members or forging members, and can be assembled by welding. Other members such as mounting blocks or covers can be formed from plastic or other low-friction materials, which can be molded.

[0082] Optionally, at least a part, if not all, of the pivot connection portions can be provided with foreign object intrusion prevention property, and in some cases, a retainer 70 (FIG. 12F) that renders the lift assembly inoperable can be incorporated. Also, this makes it easier to inspect the connection portions of the lift assembly. Although the pivot connection portion 40a of the link 40 will be described in detail, it should be understood that the same or similar details apply to other pivot connection portions.

[0083] As best shown in FIG. 12F, the end of the pin 40a' of the pivot connection portion (40a) protrudes through an opening provided in the link 40. Optionally, the opening can be reinforced by a raised boss 40c. A retainer 70 is mounted around the opening on the pin 40a'. The retainer 70 is attached to the distal end of the pin 40a' via a standard pop rivet 72, which extends through the retainer 70 and also through a transverse opening provided in the distal end of the pin 40a'.

[0084] In the illustrated embodiment, the retainer 70 has a cylindrical body 70a with a closed end 70b that abuts against the distal end of the pin 40a'. The cylindrical wall 70c of the body 70a is branched to facilitate installation onto the end of the pin 40a', whereby a tool can similarly be used, but the pin 40a' can be manually attached to the distal end. Optionally, the body 70a has a flange-like end 70d that forms an annular contact surface 70e, which can provide a certain amount of thrust load, for example, when the pin 40a' pulls the washer W inward and engages with the washer W as shown in the figure of FIG. 12F. Thus, the retainer 70 provides a connection that is foreign object intrusion-proof and further easily inspectable and non-repairable to ensure correct assembly in the original manufacturing equipment.

[0085] As can be understood, since the head end lifting assembly and the foot end lifting assembly are independent, they can be moved independently, the head end or the foot end of the support frame can be raised or lowered, and the deck can be moved to the Trendelenburg position or the reverse Trendelenburg position (see FIGS. 1A and 5). Further, the speed of each actuator can be controlled independently. For example, a suitable actuator has an actuator from Linak, such as model number LA40, or an actuator from Ilcon. For example, the actuator can have a sensor or magnet for measuring the speed of the actuator so that the operation and speed of each actuator can be independently controlled as described above.

[0086] Referring to FIG. 9H, in a standard hospital bed of one embodiment, the actuator force ranges from about 5300N to 5400N when in the lowest position, from about 5700N to 5800N when at an intermediate position approximately between the lowest positions, and then can return to a range of about 3200N to 3300N when in the uppermost position. As is commonly understood, the maximum force is required when the lift assembly is most compact and in the lowest position. However, due to the current arrangement of the links and crank arms, the moment arm is maximized when the leg assembly is in the lowest position, and as described above, the initial starting force (SF) is less than the maximum force F1. As the lifting legs rise relative to the base, the lever action provided by the crank arm decreases until the lift assembly reaches an intermediate region about 48 cm (19 inches) to 61 cm (24 inches) away from the floor, and thus the required force increases. As the lift assembly continues to rise, as shown in FIG. 9H, the lever action provided by the crank arm further decreases at a reduced rate until the lift assembly reaches its uppermost configuration.

[0087] With the above configuration, when the lift assembly 18 is in its lowest position, the distance from the top of the retard deck (shown in phantom in FIG. 30) to the floor can be less than 36 cm (14 inches), less than 33 cm (13 inches), or optionally less than 30 cm (12 inches), and the space under the base frame member 12a does not prevent the overbed table or the base of the lift assembly from extending under the base. For example, the distance from the lower surface of the base frame member 12a to the floor is at least 10 cm (4 inches), at least 12.7 cm (5 inches), or between about 12.7 cm (5 inches) and about 15.2 cm (6 inches), providing a minimum clearance of about 5.1 cm (2 inches) to 7.6 cm (3 inches) or about 6.1 cm (about 2.4 inches) below the lowermost member for patient support. Further, when the lift assembly is in its raised position, the lifting legs move outwardly towards the ends of the frame, thereby leaving sufficient space for an X-ray fluoroscopy device to extend between the frame and the base.

[0088] Although not described in each example, the structural components of the frame, deck, and lift assemblies can be formed from metal structural members such as steel and can be welded (as described in some cases), or fastened together by, for example, bolts, rivets, pins, or screws, or simply mechanically coupled (as described above in connection with some of the brackets). Further, features of one embodiment can be combined with features of another embodiment. Additionally, it should be understood that, for example, the actuators can be controlled to extend or contract independently so that one end of the patient support device can be raised or lowered to orient the patient support device deck in the Trendelenburg or reverse Trendelenburg position.

[0089] Terms indicating directions such as "vertical", "horizontal", "top", "bottom", "upper", "lower", "inner", "inwardly", "outer", and "outwardly" are used to assist in describing the present disclosure based on the orientation of the embodiments shown in the figures. The use of the directional terms should not be construed as limiting the present disclosure to any particular direction.

[0090] Without departing from the technical idea and broader aspects of the disclosure defined in the appended claims, various alternatives and modifications can be made to the above-described embodiments, and these should be construed in accordance with the principles of the patent law including equivalence. This disclosure is presented for illustrative purposes and should not be construed as an exhaustive description of all embodiments of the present invention, nor should the claims be construed as being limited to the specific elements illustrated or described in connection with these embodiments. For example, without limitation, any individual element of the invention described herein can be replaced with an alternative element that provides substantially similar functionality or otherwise provides proper operation. This includes currently known alternative elements such as those currently known to those skilled in the art, as well as potentially future-developed alternative elements that those skilled in the art could recognize as alternative elements during development. Further, the disclosed embodiments have multiple features that are simultaneously described and can provide many benefits in a coordinated manner. The present invention is not limited to having all of these features except as specified in the published claims, or to only those embodiments that provide all of the described benefits. For example, the use of the articles "a", "an", "the", or "said" to refer to an element in the singular in a claim should not be construed as limiting that element to the singular. Also, this disclosure includes the following inventions. A first aspect is In a patient support device, The patient support device is A base, A frame supported with respect to the base and configured to support a deck for supporting a patient thereon, A lift assembly that raises or lowers the frame with respect to the base and is rotatably connected to the frame at its upper end and rotatably connected to the base at its lower end, the lift assembly having a first leg and a second leg, the second leg being rotatably attached to the first leg at its central portion so as to form an inverted Y-shaped leg assembly when deployed, a lift assembly A patient support device comprising an actuator mounted within the leg assembly, the actuator having a mounting configuration that generates a maximum force F1 when raising the frame that occurs after the lift assembly has risen from its lowest configuration. A second aspect is The patient support device according to the first aspect, wherein the maximum force F1 occurs at approximately the mid-stroke of the lift assembly. A third aspect is The patient support device according to the first or second aspect, wherein the actuator is mounted within the leg assembly with a mounting configuration that generates a starting force SF within the range of 96% to 98% of the maximum force F1. A fourth aspect is The patient support device according to the first or second aspect, wherein the actuator is mounted within the leg assembly with a mounting configuration that generates a starting force SF that is approximately 97% of the maximum force F1. A fifth aspect is The patient support device according to the first or second aspect, wherein the actuator is mounted with a configuration that generates a minimum force F2 when raising or lowering the frame, and the minimum force F2 is in the range of 50% to 70% of the maximum force F1. A sixth aspect is The patient support device according to the first or second aspect, wherein the actuator is mounted with a configuration that generates a minimum force F2 when raising or lowering the frame, and the minimum force F2 is approximately 60% of the maximum force F1. A seventh aspect is In a patient support device The patient support device A base, A frame supported by the base and configured to support a deck for supporting a patient thereon. A lift assembly that raises or lowers the frame relative to the base and is rotatably connected to the frame at its upper end and rotatably connected to the base at its lower end, the lift assembly having a first leg and a second leg, the second leg being rotatably attached to the first leg at its central portion so as to form an inverted Y-shaped leg assembly when deployed. An actuator mounted within the leg assembly in a mounting configuration that generates a maximum force F1 and a minimum force F2 when raising or lowering the frame, the minimum force F2 being in the range of 55% to 65% of the maximum force F1, a patient support device comprising the actuator. The eighth aspect is The patient support device according to the seventh aspect, wherein the minimum force F2 occurs at the maximum height of the lift assembly. The ninth aspect is The patient support device according to the seventh or eighth aspect, wherein the actuator is mounted within the leg assembly in a mounting configuration that generates a starting force SF, and the minimum force F2 is within the range of 55% to 65% of the starting force SF. The tenth aspect is In a patient support device The patient support device A base, A frame supported relative to the base, the frame being configured to support a deck for supporting a patient thereon. A lift assembly that raises or lowers the frame relative to the base and is rotatably connected to the frame at its upper end and rotatably connected to the base at its lower end. Comprising an actuator, The lift assembly has a first leg and a second leg, and the second leg is rotatably attached to the first leg at its central portion about a bending rotation axis so as to form a Y-shaped leg assembly when deployed. The actuator is mounted within the leg assembly between a first pivot connection portion with the first leg portion and a second sliding pivot connection portion with the first leg portion. The second sliding pivot connection portion is connected to the second leg portion. When the actuator expands and contracts, the first leg portion and the second leg portion are deployed or bent relative to each other, which is a patient support device. The eleventh aspect is The first leg portion has an upper pivot connection portion with the frame and a lower pivot connection portion with the base. The patient support device further includes a drive link that is slidably connected to the first leg portion by a sliding link pivot connection portion and is eccentrically connected to the second leg portion, which is the patient support device in the tenth aspect. The twelfth aspect is The sliding link pivot connection portion between the drive link and the first leg portion includes a non-linear sliding pivot connection portion, which is the patient support device in the eleventh aspect. The thirteenth aspect is When the lift assembly is in the lowest position, the sliding link pivot connection portion between the drive link and the first leg portion extends below the lower pivot connection portion of the first leg portion, which is the patient support device in the eleventh aspect. The fourteenth aspect is In a patient support device The patient support device includes a base a frame supported by the base and configured to support a deck for supporting a patient thereon a lift assembly configured to raise or lower the frame relative to the base and pivotally connected to the frame at its upper end and pivotally connected to the base at its lower end and an actuator The lift assembly has a first leg portion and a second leg portion. The second leg portion is pivotally attached to the first leg portion at its central portion so as to form an inverted Y-shaped leg assembly when deployed. The second leg portion has a crank arm. The patient support device further includes a drive link having a first end and a second end, wherein the first end of the drive link is rotatably connected to the actuator, the second end of the drive link is connected to the crank arm and moves along a non-linear path, thereby pushing or pulling the crank arm within a certain angular range, thereby causing the first leg and the second leg to be deployed or bent relative to each other, or causing the lift assembly to contract or extend, and is configured as a patient support device. A fifteenth aspect is the patient support device according to the fourteenth aspect, wherein the first leg has an upper pivot connection with the frame and a lower pivot connection with the base, and the drive link is slidably connected to the first leg by a sliding pivot connection and is eccentrically connected to the crank arm. A sixteenth aspect is the patient support device according to the fifteenth aspect, wherein the sliding pivot connection includes a non-linear sliding pivot connection. A seventeenth aspect is In a patient support device, the patient support device includes a base, a frame supported by the base and configured to support a deck for supporting a patient thereon, a head end actuator, a foot end actuator, A lift assembly for raising or lowering the frame relative to the base, the lift assembly having a head end leg assembly and a foot end leg assembly, each of the lift assemblies having a pair of legs, the head end leg assembly and the foot end leg assembly having a pair of legs, each pair of legs forming an inverted Y-shaped configuration when raising the frame and being bent when lowering the frame, having a first leg and a second leg, the first leg being rotatably attached to the frame at its upper end and rotatably attached to the base at its lower end, each pair of legs having a bending rotation axis, each of the head end actuator and the foot end actuator having a rotational connection portion to the respective first leg and having a sliding lower rotational connection portion connected to the respective first leg, the first legs and the second legs of each of the head end leg assembly and the foot end leg assembly being connected such that expansion and contraction of the respective actuator expands or bends each of the head end leg assembly and the foot end leg assembly to raise or lower the frame, a patient support device comprising the lift assembly. The 18th aspect is The patient support device according to the 17th aspect, wherein each of the first legs is connected to the respective second leg by a drive link, and the drive link is eccentrically attached to the respective second leg. The 19th aspect is The patient support device according to the 18th aspect, wherein one end of each of the drive links is connected to the respective first leg by a sliding rotational connection portion having an arcuate path. The 20th aspect is The patient support device according to the 19th aspect, wherein the sliding rotational connection portion of the actuator to the first leg has a linear path.

Claims

1. In a patient support device, the patient support device includes a base, a frame supported by the base and configured to support a deck for supporting a patient thereon, a lift assembly configured to raise or lower the frame relative to the base, rotatably connected to the frame at its upper end and rotatably connected to the base at its lower end, the lift assembly having a first leg and a second leg, the second leg being rotatably attached to the first leg at its central portion so as to form an inverted Y-shaped leg assembly when deployed, the lift assembly being configured to be raised from its lowest configuration by a starting force SF smaller than a maximum force F1 when raising the frame relative to the base after the lift assembly has been raised from its lowest configuration, an actuator mounted within the lift assembly having a mounting configuration for generating the maximum force F1 that occurs when raising the frame after the lift assembly has been raised from its lowest configuration, generating a minimum force F2 when lowering or raising the frame after the lift assembly has been raised from its lowest configuration, and generating the starting force SF smaller than the maximum force F1 in its lowest configuration, the minimum force F2 being in the range of 50% to 70% of the maximum force F1, the patient support device comprising the actuator.

2. The maximum force F1 occurs under an intermediate stroke of the lift assembly, the patient support device according to claim 1.

3. The actuator is mounted within the lift assembly in a mounting configuration for generating the starting force SF within the range of 96% to 98% of the maximum force F1, the patient support device according to claim 1 or 2.

4. The actuator is mounted within the lift assembly in a mounting configuration for generating the starting force SF that is about 97% of the maximum force F1, the patient support device according to claim 1 or 2.

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