Patient support with a lifting assembly

Abstract

A patient support device, comprising: a frame supported relative to the ground, the frame being configured to support a platform for supporting a patient thereon; and a lifting assembly for raising or lowering the frame relative to the ground. The lifting assembly includes: lifting legs coupled to the frame; and an actuator having a body and an extendable member. The actuator is mounted to one of the legs rather than to the frame, and is mounted to perform a linear motion relative to one leg, and this linear motion is converted into a rotational motion of the other leg through a linkage and crank arm device.

Description

[0001] This application claims the benefit of U.S. Provisional Application No. 62 / 948,540, filed on December 16, 2019 (P-600) and entitled "PATIENT SUPPORT WITH LIFT ASSEMBLY", the entire content of which is incorporated herein by reference. BACKGROUND OF THE INVENTION

[0002] The present disclosure relates to a patient support device with a lift assembly for raising or lowering a patient support device platform relative to a floor surface. More specifically, the present disclosure relates to a patient support device with a lift assembly capable of lowering the patient support device platform to a very low height while still providing a full range of motion at a height where a caregiver can access the patient. SUMMARY OF THE INVENTION

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

[0004] In one form, the patient support device includes a base, a frame supported relative to the base, the frame being configured to support a platform for supporting a patient thereon. The patient support device further includes a lift assembly for raising or lowering the frame relative to the base. The lift assembly includes a first leg and a second leg, wherein the first leg is pivotally coupled to the frame at its upper end and pivotally and slidably coupled to the base at its lower end. The second leg is pivotally mounted to an intermediate portion of the first leg at its upper end to form an inverted Y-shaped leg assembly when deployed. The lift assembly further includes an actuator mounted to the leg assembly having a mounting configuration to produce a maximum force F1 when raising the frame after the lift assembly has been raised from its lowest configuration. For example, the maximum force F1 may be generated approximately at the mid-stroke of the lift assembly.

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

[0006] In one aspect, the actuator has a mounting configuration to produce a minimum force F2 when raising or lowering the frame, wherein the minimum force F2 is in the range of 50% to 70% of the maximum force F1, and optionally, approximately 60% of the maximum force F1.

[0007] In another embodiment, the patient support device includes: a base; a frame supported relative to the base, the frame being configured to support a platform for supporting a patient thereon; and a lifting assembly for raising or lowering the frame relative to the base. The lifting assembly is pivotally coupled to the frame at its upper end and pivotally coupled to the base at its lower end. The lifting assembly includes a first leg and a second leg, and the second leg is pivotally mounted to the first leg at an intermediate portion of the first leg to form an inverted Y-shaped leg assembly when deployed. An actuator is mounted in the leg assembly and has a mounting configuration to produce a maximum force F1 and a minimum force F2 when raising or lowering the frame, where 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 produced at the maximum height of the lifting assembly.

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

[0009] In another embodiment, the patient support device includes: a base; a frame supported relative to the base, the frame being configured to support a platform for supporting a patient thereon; and a lifting assembly for raising or lowering the frame relative to the base. The lifting assembly is pivotally coupled to the frame at its upper end and pivotally coupled to the base at its lower end. The lifting assembly includes an actuator, a first leg, and a second leg. The second leg is pivotally mounted to the first leg at an intermediate portion of the first leg to form an inverted Y-shaped leg assembly when deployed. The actuator is mounted in the leg assembly, one end of the actuator is mounted to the first leg through a first connecting member, and its opposite end is connected to the first leg through a second sliding pivot connecting member.

[0010] In one aspect, the second sliding pivot connecting member is connected to the second leg, and when the actuator extends or contracts, the first leg and the second leg unfold or fold relative to each other.

[0011] In another aspect, the first leg includes an upper pivot connecting member connected to the frame, a lower pivot connecting member connected to the base; and further includes a drive link, one end of the drive link is coupled to the actuator, and its opposite end is coupled to the first leg through a sliding link pivot connecting member. The drive link is eccentrically coupled to the second leg.

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

[0013] In another aspect, when the lifting assembly is in its lowest position, the sliding link pivot connecting member between the drive link and the first leg extends below the lower pivot connecting member of the first leg.

[0014] In yet another embodiment, the patient support device includes: a base; a frame supported relative to the base, the frame being configured to support a platform for supporting a patient thereon; and a lifting assembly for raising or lowering the frame relative to the base. The lifting assembly is pivotally coupled to the frame at its upper end and pivotally coupled to the base at its lower end. The lifting assembly includes an actuator, a first leg, and a second leg, the second leg being pivotally mounted to the first leg at an intermediate portion of the first leg to form an inverted Y-shaped leg assembly when deployed. The second leg has a crank arm. The lifting assembly further includes a drive link having a first end and a second end. The first end of the drive link is pivotally connected to the actuator. The second end of the drive link is connected to the crank arm and is configured to move along a non-linear path so as to push or pull the crank arm from a certain angular range and thereby deploy or fold the first leg and the second leg relative to each other to contract or extend the lifting assembly.

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

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

[0017] According to yet another embodiment, the patient support device includes: a base; a frame supported relative to the base, the frame being configured to support a platform for supporting a patient thereon; a head end actuator; and a foot end actuator. The patient support device further includes: a lifting assembly for raising or lowering the frame relative to the base; the lifting assembly includes a head end leg assembly and a foot end leg assembly. Each leg assembly has a pair of legs, each pair of legs including a first leg and a second leg; the first leg and the second leg form an inverted Y-shaped structure when the frame is raised and are folded into a substantially flat shape when the frame is lowered. The first leg is pivotally mounted to the frame at its upper end and pivotally mounted to the base at its lower end. Each pair of legs has a folding pivot axis. Each of the head end actuator and the foot end actuator has a first connection member to its corresponding first leg and has a sliding lower pivot connection member to its corresponding first leg; wherein the first leg and the second leg of each leg assembly are connected such that the extension and contraction of their corresponding actuators will deploy or fold the leg assembly to raise or lower the frame.

[0018] In one aspect, each first leg is connected to its corresponding second leg by a drive link, and the drive link is eccentrically mounted to its corresponding second leg.

[0019] In another aspect, one end of each drive link is coupled to its corresponding first leg through a sliding pivot connection member having an arcuate path.

[0020] On the other hand, the sliding pivot connection of the actuator with the first leg 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 lift leg of the head end leg assembly is pivotally mounted at a head end pivot connection located at or near the head end of the frame, and the lift leg of the foot end leg assembly is pivotally mounted at a foot end pivot connection located at or near the foot end of the frame.

[0023] On the other hand, the head end and foot end pivot connections are offset below the frame.

[0024] In another embodiment, the patient support device includes: a base; a frame supported relative to the base, the frame being configured to support a platform for supporting a patient thereon; and a lifting assembly. The lifting assembly includes a head end leg assembly and a foot end leg assembly. Each leg assembly has an actuator and forms an independent assembly; the independent assembly can be installed between the base and the support frame as an assembled unit, simply by inserting the pivot connection between the leg assembly and the base and coupling the pivot connection between the leg assembly and the support frame.

[0025] For example, in one aspect, when the lifting assembly moves the support frame to the raised position, both the head end leg assembly and the foot end leg assembly have an inverted Y-shaped configuration.

[0026] In yet another aspect, at least one leg assembly includes first and second lift legs. Optionally, the first lift leg includes an inverted U-shaped frame. Similarly, the second lift leg may include a second inverted U-shaped frame. In another embodiment, one or both of the lift legs may be L-shaped.

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

[0028] According to yet another embodiment, the patient support device includes: a base; a frame supported relative to the base, the frame being configured to support a pad for supporting a patient thereon; and a lifting assembly for raising or lowering the frame relative to the base. The lifting assembly includes a first lift leg and a second lift leg. One end of a linear actuator is mounted on the first lift leg, and the other end is mounted on the first lift leg for linear movement relative to the first leg. The second lift leg is connected to the actuator such that when the linear actuator extends or contracts, the second lift leg pivots about the first lift leg.

[0029] In yet another aspect, the second lift leg includes a crank arm that is connected to the actuator by a link such that extension or contraction of the actuator causes rotation of the second lift 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 accompanying drawings.

[0031] Before explaining the embodiments of the present disclosure in detail, it should be understood that the present disclosure is not limited to the operating details or structural details and the arrangement of components set forth in the following description or shown in the drawings. The present disclosure can be implemented in various other embodiments and can be practiced or carried out in alternative ways not explicitly disclosed herein. In addition, it should be understood that the wording and terms used herein are for the purpose of description and should not be regarded as limiting. The use of "including" and "comprising" and their variants is intended to cover the items listed thereafter and their equivalents and additional items and their equivalents. In addition, enumeration can be used in the description of various embodiments. Unless otherwise explicitly stated, the use of enumeration should not be construed as limiting the disclosure to any specific order or number of components. The use of enumeration should also not be construed as excluding any additional steps or components that may be combined with or incorporated into the enumerated steps or components from the scope of the present disclosure. Description of the Drawings

[0032] Figure 1 is a side view of a patient support device;

[0033] Figure 1A is Figure 1 a perspective view of the patient support device of

[0034] Figure 1B is Figure 1 a side view of the patient support device of

[0035] Figure 1C is Figure 1 a plan view of the patient support device of

[0036] Figure 2 is Figure 1 a perspective view of the patient support device of

[0037] Figure 2A is Figure 2 an enlarged view of the foot end leg assembly of the lifting assembly of

[0038] Figure 3 is similar to Figure 2Another perspective view of the patient support device, showing the lifting assembly in the intermediate height position;

[0039] Figure 3A is Figure 3 An enlarged view of the foot end leg assembly of the lifting assembly;

[0040] Figure 4 is similar to Figure 2 Another perspective view of the patient support device, showing the lifting assembly in the lowest position;

[0041] Figure 4A is Figure 4 An enlarged view of the foot end leg assembly of the lifting assembly;

[0042] Figure 5 is similar to Figure 2 Another perspective view of the patient support device, showing the lifting assembly in the Trendelenburg position;

[0043] Figure 6 A side view of the patient support device, where the platform, frame, headboard, and footboard are removed to show the lifting assembly in its fully height configuration;

[0044] Figure 6A is Figure 6 An enlarged view of the foot end leg assembly of the lifting assembly;

[0045] Figure 7 is similar to Figure 6 A side view, where the lifting assembly is in its intermediate height position;

[0046] Figure 7A is Figure 7 An enlarged view of the foot end leg assembly of the lifting assembly;

[0047] Figure 8 is similar to Figure 6 A side view, where the lifting assembly is in its lowest position;

[0048] Figure 8A is Figure 8 An enlarged view of the foot end leg assembly of the lifting assembly;

[0049] Figure 9 is similar to Figure 6 A side view, where the lifting assembly is in its Trendelenburg position;

[0050] Figure 9A An enlarged perspective view of the lifting assembly;

[0051] Figure 9B An enlarged perspective view of the lifting assembly;

[0052] Figure 9C Is an enlarged perspective view of the lifting assembly with the actuator removed;

[0053] Figure 9D Is an enlarged perspective view of the lifting assembly with the actuator removed;

[0054] Figure 9E Is an enlarged perspective view of the lifting assembly with the actuator removed;

[0055] Figure 9F Is an enlarged perspective view of the lifting assembly with the actuator removed;

[0056] Figure 9G Is an enlarged perspective view of the lifting assembly with the actuator removed;

[0057] Figure 9H Is a graph of force and force margin versus actuator stroke;

[0058] Figure 10 Is an enlarged partial external front view of the arrangement for mounting one of the leg assemblies of the lifting assembly to the base of the patient support device;

[0059] Figure 10A Is an enlarged cross-sectional view of the base frame member showing the slider of the lifting assembly;

[0060] Figure 10B Is Figure 10A An enlarged perspective view of the slider of;

[0061] Figure 10C Is an enlarged front view of the mounting block;

[0062] Figure 11 Is an enlarged partial internal front view of the arrangement for mounting one of the leg assemblies to the base of the patient support device;

[0063] Figure 12 Is an enlarged perspective view of one of the leg assemblies of the lifting assembly and the actuator;

[0064] Figure 12A Is an enlarged perspective view of one of the lifting legs of the lifting assembly;

[0065] Figure 12B Is Figure 12A A second enlarged perspective view of the lifting leg of;

[0066] Figure 12C Is a perspective view of another lifting leg of the lifting assembly;

[0067] Figure 12D Is an enlarged perspective view of one of the linkages of the lifting assembly;

[0068] Figure 12Eis an enlarged perspective view of another link of the lifting assembly; and

[0069] Figure 12F is an enlarged perspective view of a typical pivot connection of the lifting assembly. DETAILED DESCRIPTION

[0070] Referring to Figure 1 , numeral 10 generally denotes a patient support device. In the illustrated embodiment, the patient support device 10 is configured as a bed (e.g., a hospital bed), having a headboard and a footboard 10a, 10b, side rails (not shown), and an articulated platform 16. However, it should be understood that the patient support device 10 may take other forms, including stretchers, cribs, etc. Generally, whenever a patient is to be supported and it is desired to raise and lower the patient relative to a floor surface or other support surface, the patient support device 10 is used. As will be described more fully hereinafter, the patient support device 10 includes a lifting assembly for raising and lowering a patient support device surface (e.g., a mattress or other cushioning means on which the patient support device surface supports the patient) between a fully raised position and a lowest position, while still leaving sufficient clearance to allow a bedside table or the base of a patient lift to extend beneath the patient support device.

[0071] As Figure 2 best shown, the patient support device 10 includes: a base 12, a support frame 14 for supporting the platform 16( Figure 1 ), and a lifting assembly 18 for raising or lowering the support frame 14 (and the platform 16, see Figure 1 ) relative to the base 12. It should be understood that the frame 14 may also support a load frame below the platform 16, which is used to mount sensors (e.g., piezoresistive elements) to measure the weight of a patient supported on the platform. However, the load frame may be dispensed with. Instead, the piezoresistive elements may be placed in the frame 14 because of the reduction of forces, especially the torque on the frame 14, which is achieved by the arrangement of the components of the lifting assembly described more fully below.

[0072] As Figure 2 best shown, the base 12 is a wheeled base with a plurality of casters 15 so that the bed can move on a floor surface. In the illustrated embodiment, again referring to Figure 1, the platform 16 includes a plurality of articulated platform sections 16a, 16b, 16c, 16d, and 16e. However, it should be understood that the number of platform sections can vary. Each platform section can be articulated by an actuator (not shown) to raise or lower the platform section, for example, to orient the platform section into a flat structure or a chair structure (as well as various other structures therebetween). The structure of any one of the base 12, the support frame 14, the headboard 10a, the footboard 10b, and / or the side rails can adopt any known design; for example, those disclosed in U.S. Patent No. 7,690,059 entitled "HOSPITAL BED" and commonly assigned to Stryker Corporation, the entire disclosure of which is incorporated herein by reference in its entirety; or, U.S. Patent No. 8,689,376 entitled "PATIENT HANDLING DEVICE INCLUDING LOCAL STATUS INDICATION, ONE-TOUCH FOWLER ANGLE ADJUSTMENT, AND POWER-ON ALARM CONFIGURATION" and also commonly assigned to Stryker Corporation, the entire disclosure of which is also incorporated herein by reference in its entirety. The construction of any one of the base 12, the support frame 14, the headboard 10a, the footboard 10b, and / or the side rails can also adopt a form different from that disclosed in the above patents and patent disclosures.

[0073] As will be described more fully below, the lift assembly 18 is configured such that an actuator with a shorter stroke and a consistent force margin ("the applied force is less than the actuator capacity") can be used, while still being able to lower the platform to a low height position (e.g., 11 inches from the ground), and raise the platform to a full height position (e.g., in the range of 26 to 34 inches from the ground). In other words, the same energy can be applied by better optimizing the force curve. In this way, a lower maximum load can be applied to the assembly, such as the weldments forming the leg assembly. Additionally, this can reduce costs and allow the use of lighter actuators.

[0074] Optionally, by providing sufficient clearance in the actuator mounting arrangement, the actuator can be mounted to reduce (if not eliminate) any lateral loads on the lift legs, but without too much clearance that would cause lateral loads at its rod mounting position. Additionally, instead of being mounted to the frame as described above, the actuator is fully contained and mounted within the leg assembly as described below, which reduces the forces on the frame such that a pressure element can be mounted to the frame to measure the patient's weight, as well as movement and patient biometrics.

[0075] Additionally, when the lift assembly 18 moves to its lowest configuration, as Figure 4 and8 As shown, the lifting assembly 18 can be substantially contained within the base 12 without interfering with the central space S below the base, which may, for example, be required for mounting drive wheels and a controller for a wheel drive system (such as the ZOOM system sold by Stryker). Thus, for example, when the patient support device 10 is lowered, the patient support device 10 can be configured such that the central space S below the base is clear for at least a length S1 of approximately 18 inches. In this way, the patient support device 10 can provide a very low height patient support device, which can reduce the chance of patient falls, but does not eliminate the available space under the base.

[0076] Referring again to Figure 2 , the lifting assembly 18 includes a head end lifting assembly 18a and a foot end lifting assembly 18b, which can be substantially mirror images of each other and are mounted near the respective head end and foot end of the frame 14. For ease of description, many of the following details are given with reference to the head end lifting assembly 18a, and it should be understood that the same details apply to the shown foot end lifting assembly 18b (which is shown as a mirror image and is numbered with the same numbers as the head end lifting assembly). However, it should be understood that the head end and foot end lifting assemblies can have different configurations.

[0077] As Figure 1A best shown, the frame 14 includes a pair of longitudinal frame members 14a and a pair of transverse frame members 14b, and the transverse frame members 14b connect the longitudinal frame members 14a to form the frame. Referring to Figure 2 , 2A , 3, 3A, 4, and 4A, the head end lifting assembly 18a includes a first lifting leg 20 and a second lifting leg 22, which are pivotally connected by a pivot connection 30 (best seen in Figure 3A ) to form a folding leg assembly 21. The pivot connection 30 is formed by a pin 30a ( Figure 9F ), and the pin 30a pivotally connects the first lifting leg 20 to the second lifting leg 22 through openings 30b, 30c formed in the respective legs 20, 22 (see Figure 12A and 12C ).

[0078] The first lifting leg 20 is pivotally mounted at its upper end to the support frame 14 by a pivot connection 24 ( Figure 1A ), and the pivot connection 24 is formed by a pair of pins, which are pivotally mounted to the frame 14, for example, through a pivot block 14d, and the pivot block 14d is mounted to the transverse frame member 14b of the frame 14 by a bracket 14c. Optionally, the pivot connection 24 can be formed by a single pivot rod 24a (shown in Figure 2Ais formed as shown by the dashed line. The pivot rod 24a extends laterally below the upper lateral frame member 44 (described below) and enters the upper end of the leg 20 to extend through the pivot block 14d. As described below, when the lifting assembly descends and folds, the pivot block 14d nests in the upper end of the leg 20. Optionally, the rod 26a can be supported by an intermediate bracket 24b ( Figure 2A ), and the intermediate bracket 24 is mounted to the lower side of the frame member 44.

[0079] The lifting leg 20 is pivotally mounted to the base 12 at its lower end at a sliding pivot connection 26, such as through a pivot block 60 (described more fully below). The second lifting leg 22 is pivotally mounted to the base 12 at its lower end at a pivot connection 28 and is pivotally mounted near its upper end to an intermediate portion of the lifting leg 20 at a pivot connection 30. In this way, when the legs 20 and 22 are deployed about the pivot connection 30, they form an inverted Y-shaped frame, and when folded, they are generally arranged in a flat structure (see Figure 4 ). Additionally, as will be described more fully below, when folded, the legs 20 and 22 can be disposed within the base 12 such that the platform 16 can be lowered to a height H less than 12 inches from the surface of the support base. Optionally, also as will be described more fully below, when folded, the second lifting leg 22 can provide a support surface for the lifting leg 20 in the form of, for example, a stop 22a (see Figure 1 ) such that the load of the frame and the platform can be directly transferred to the base 12 through the pivot connections 26 and 28.

[0080] As will be described more fully below, the lifting assembly 18a (and the lifting assembly 18b) includes 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 of the head actuator 36 (the fixed base 36d, such as Figure 2A and Figure 3 ) is mounted to the upper end of the first lifting leg 20, for example, through pivot connections 37a and brackets 37b, and is also mounted to the first lifting leg 20 at its opposite end through a sliding pivot connection 37c. In this way, when the telescopic rod 36a extends, it extends along an axis 36b that is fixed relative to the first lifting leg 20 (further details will be provided below). In other words, the actuator does not pivot relative to the first lifting leg 20 but instead optionally extends generally parallel to the lifting leg 20 (e.g., at least the upper linear portion of the lifting leg 20, see further details below regarding the optional structure of the first lifting leg 20).

[0081] To convert the linear motion of the actuator 36 into the pivoting motion of the second lift leg 22 (and the lifting motion of the lift assembly 18a), the lift leg 22 is coupled to the actuator by a linkage and crank arm arrangement. Additionally, as will be described more fully below, the linkage and crank arrangement can be configured to adjust the force curve of the lift assembly to closely match the allowable force of the actuator.

[0082] For example, in one embodiment, the actuator, linkage, and crank arm arrangement in the lift assembly are configured to produce a maximum force F1 when raising the frame 14 after the lift assembly 18 has been raised from its lowest configuration. Referring to Figure 9H , the maximum force F1 may occur approximately in the middle stroke of the lift assembly. Additionally, the actuator, linkage, and crank arm arrangement are mounted in the leg assembly 21 with a mounting configuration to produce a starting force SF, where the starting force SF is in the range of 95% to 99% of the maximum force F1, or in the range of 96% to 98% of the maximum force F1, or approximately 97% of the maximum force F1 (see Figure 9H ). As a result, the actuator can have a shorter stroke size than other commonly used actuators, and in addition, can have a consistent force margin, where the force margin varies in the range from approximately 1500 Newtons to approximately 3000 Newtons (see Figure 9H ).

[0083] Additionally, by doing so, the lifting speed of the platform is more uniform throughout its entire motion range, which is more comfortable for the patient supported thereon. For example, the speed of the actuator can be more consistent throughout its entire motion range and can be in the range of approximately 0.7 to 1.3 distance / time. It should be understood that this speed will vary depending on the weight of the patient supported thereon and the capacity of the selected actuator.

[0084] In the illustrated embodiment, and referring to Figure 9A - 9G , the second lift leg 22 is coupled to the actuator 36 by a pair of crank arms 32 and by linkages 38, 40. Each crank arm 32 is fixedly mounted at its upper end to the second lift arm 22 and is pivotally coupled at its lower end to the corresponding linkage 40 by a pivot connection 32a. In turn, each linkage 40 is pivotally coupled to the linkage 38 by a pivot connection 40a. Additionally, the linkage 38 is pinned to the actuator 36 at its opposite end by a lateral pin 36c mounted on the distal end of the rod 36a of the actuator 36. Thus, when the rod 36a extends or retracts along the axis 36b, the distal end of the linkage 38 extends along the axis 36b. Additionally, the pin 36c and the distal end of the linkage 38 move in a linear path P1, which will be described more fully below. Optionally, the distal end of the linkage 38 can have a slotted opening 38a formed therein for receiving the pin 36c to assist in unloading the force on the actuator at low heights, as will be described more fully below with reference to the stop 22a.

[0085] As Figure 9A - 9C Best shown, the link 38 extends rearwardly from the pin 36c towards the fixed base 36d of the actuator 36. Additionally, the link 38 forms an acute angle with the rod 36a throughout its range of motion, as described below, while its distal end moves along the path P1. The relatively proximal end of the link 38 (at the pivot connection 40a) is guided along a non-linear path P2 (see Figure 9E - 9G and 1A), which non-linear path P2 deviates at least initially from the linear path P1 of the pin 36c, or in other words, from the axis 36b. As described above, the rod 36a of the actuator extends along the axis 36b; this axis 36b is fixed and at least generally parallel to the linear portion of the lifting leg 20. Thus, when the rod 36a extends, the link 38 will become a tension-driven link, pulling the pin 40a' of the pivot connection 40a along the path P2, and thereby pushing the link 40. The link 40 in turn pushes the crank arm 32, which applies a moment to the second lifting leg 22 causing them to rotate counterclockwise about the pivot connection 30 (e.g., as Figure 9A shown), and deploy the leg assembly 21 until the pin 40a' of the pivot connection 40a reaches the end of the path P2. Conversely, it will be appreciated that when the rod 36a retracts, the link 38 will become a compression-driven link, pushing the pin 40a' along the path P2 (towards the fixed base 36d of the actuator 36), and thereby pulling the link 40. The link 40 in turn pulls the crank arm 32, which applies a moment to the second lifting leg 22 causing them to rotate clockwise about the pivot connection 30 (e.g., as Figure 9E shown), and fold the leg assembly 21 until the pin connection 40a reaches the other end of the path P2. It will be understood that the path P2 can extend beyond the path of the pivot connection 40a such that the end of the path of the pivot connection 40a is defined by the actuator 36 rather than by a hard stop at either end of the path P2.

[0086] To maintain the rod 36a of the actuator 36 along its fixed linear path, the first lifting arm 20 includes a track 42 that extends along and from the axis 36b, which track 42 guides the rod 36a of the actuator 36 as it extends or retracts. In the illustrated embodiment, the track 42 is formed by a pair of opposing plates 48 (e.g., stamped plates) having slots 48a. The slots 48a are for guiding the pin 36c of the rod 36 along its linear path P1 along the axis 36c. Optionally, as described more fully below, the plates 48 can be configured to provide a support surface 48b for the pin 36c along the edge of the slot 48a to reduce tilt and clearance and provide a tighter assembly. For example, the support surface 48b can be provided by a lip formed in the plate 48 at least along the lower edge of the slot 48a, but it can extend around the entire perimeter of the slot to reinforce the plate at the slot location.

[0087] In the illustrated embodiment, with reference to Figure 9A , the first lifting leg 20 is formed by an inverted U-shaped frame having a laterally upper frame member 44 and two pendant frame members 46 which are connected together, for example, by welding. An actuator 36 is mounted on the lifting leg 20 between the frame members 46, and its upper end is mounted to the laterally frame member 44 by a pivot connection 37a. The pivot connection 37a may be formed by a bracket 37b, such that a pair of plate brackets are connected to the laterally frame member 44, for example, by welding.

[0088] The track 42 (which, as described above, guides the rod end 36a along the axis 36b) extends from the laterally upper frame member 44 and is supported and rigidly mounted (e.g., by welding) to the laterally frame member 44 at one end (see Figure 9A and 2A ). The track 42 is also supported and mounted to a second laterally frame member 50. The laterally frame member 50 is spaced apart from the laterally frame member 44 and is rigidly mounted between the frame members 46, for example, by welding; and in addition to providing support for the track 42, the laterally frame member 50 also provides rigidity for the frame members 46.

[0089] In the illustrated embodiment, the second lifting leg 22 may also be formed by an inverted U-shaped frame having a laterally upper frame member 56 and two pendant frame members 58 which are connected together, for example, by welding. The pendant frame members 58 straddle the frame members 46 of the first lifting leg 20 and are each pivotally connected thereto by a pivot connection 30. The laterally frame member 56 supports the crank arm 32 and provides a mounting for the crank arm 32. The crank arm 32 is rigidly connected to the laterally frame member 56, for example, by welding, and straddles the track 42.

[0090] As Figure 9A - 9G best shown, each plate 48 forming the track 42 is supported and mounted to the laterally member 44 and the laterally member 50, for example, by welding. In the illustrated embodiment, the laterally member 50 passes through an opening 48c formed in the plate 48 and is welded to the plate 48 around the opening 48c, the size of the opening 48c being commensurate with the laterally member 50. Similarly, the upper end of the plate 48 has a notch 48d formed therein ( Figure 12B ), the size of the notch 48d being adapted to receive the laterally member 44 therein such that the laterally member 44 can be welded to the corresponding plate 48 around the respective notch. Optionally, the ends of the plate 48 may extend to form the bracket 37b.

[0091] The path P2 can also be formed by a pair of slots 48e to guide the pivot connection 40a. The slots 48e can also be formed in the plate 48 and further include a support surface 48f for the pin 40a' of the pivot connection 40a, thereby reducing slack and thus increasing the tightness of the movement of the lifting assembly. Similar to the support surface 48b, the support surface 48f can be provided by one or more lips formed in the plate 48 at least along the lower edge of the slot 48e, but it can extend around the entire perimeter of the slot to reinforce the plate 48 at the slot location.

[0092] As Figure 9E Best shown, the lips forming the support surfaces 48b and 48f can extend in opposite directions from each other - that is, the support surface 48b is formed on one or more lips extending from the inner side of the plate 48, while the support surface 48f is formed on one or more lips extending from the outer side of the plate 48.

[0093] To guide the pivot connection 40a and the link 38 along a desired path and thus guide the crank arm 32, each slot 48e can be non-linear. Each slot 48e includes a first curved portion that is generally located at the distal end of the slot 48e closest to the end of the rod 36. The first curved portion forms the part where the path P2 initially deviates from the path P1 (and thus from the axis 36b). The second portion of the slot 48e can be linear but is inclined upwardly towards the 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).

[0094] In this manner, when the rod 36a is fully extended and the outrigger assembly 21 is fully raised, and then the actuator 36 is retracted, the link 38, now acting as a compression link, will push the pivot connection 40a along the first curved portion of path P2. This will pull on link 40 and cause link 40 to increase their angle relative to the crank arm 32 while pulling on the crank arm 32. Due to the divergence angle of path P2 from path P1, this increase in angle increases as the pivot connection 40a moves along the curved portion, which increases their leverage on the crank arm 32. As the rod 36a continues to retract, the pivot connection 40a will continue to move along path P2 where link 40 and the crank arm 32 increase their angular separation. The increase in angular separation increases the leverage of link 40 pulling on the crank arm 32 until the outriggers are fully folded and in their lowest position where link 40 can exert its maximum leverage. At the lowest position, due to the maximum separation of the pivot connections 26, 28, this is typically the position that requires the most torque. However, for the current configuration, at this point, the force required for the actuator 36 to move the second outrigger 22 is not the maximum but less than the maximum force. This is because the leverage of link 40 is enhanced when link 40 is in its orientation corresponding to the lowest position of the lifting assembly 18a. Thus, the shape of path P2 is such that the maximum leverage occurs where it is typically required the most force to lift the outrigger assembly. As mentioned, this is typically when the outrigger assembly 21 is at its lowest height where the pivot connections 26, 28 of the first and second outriggers 20, 22 are furthest apart. But here due to the enhanced leverage of link 40 on the crank arm 32, the force required, as described above, is not the maximum force. Conversely, when the outrigger assembly 21 is raised approximately halfway, the maximum force is required; at this time, the pivot connections 26, 28 of the first and second outriggers are still significantly separated, but the leverage of link 40 on the crank arm 32 is diminished.

[0095] In other words, when the outrigger assembly 21 is fully lowered (see Figure 9G and 8A) The pivot connection 40a is located at the proximal end of the path P2, and the link 40 is substantially perpendicular to the crank arm 32. Thus, as described above, it has the maximum leverage. Further, as described above, due to the enhanced leverage, the magnitude of the force is less than the maximum force required during raising or lowering the outrigger assembly 21. However, when the rod 36 extends, as the outrigger assembly moves from its lowest position to its intermediate position, the force required by the actuator increases. At this intermediate position, the pivot connection 40a reaches its greatest distance from the path P1 (or axis 36b), which corresponds to an angle where the link 40 forms an acute angle and thus is closer to the crank arm 32. In this orientation, the link 40 has less leverage than in the lowest position. However, as the rod continues to extend, the pivot connections 26, 28 of the first and second outriggers move closer to each other, reducing the amount of torque required for the first and second outriggers 20, 22 to continue to deploy, such that the leverage of the link 40 decreases as the link 40 approaches the distal end of the path P2. This is consistent with the reduction in the amount of torque required to move the second outrigger 22 closer to the fully raised height of the outrigger assembly 21. As a result, referring to Figure 9H , the force margin of the actuator decreases.

[0096] Although the pivot connection 40a is described as a sliding pivot connection, the pivot connection 40a can be formed by a single pin or rod 40a' extending between the link 40 and the plate 48.

[0097] Optionally, to provide additional support to the track 42, the crank arm 32 can be pivotally coupled to the track 42 by a pin or rod 58a; the pin or rod 58a passes through a perforated flange 48g extending upward from the plate 48 ( Figure 9B and 12A ).

[0098] In the illustrated embodiment, to increase the stiffness and torsional resistance of the lifting outriggers 20, 22, each frame member forming the corresponding lifting outrigger can be formed by one or more closed-section members formed of a metal such as steel. Alternatively, each lifting outrigger 20, 22 can be formed of a solid member, such as a steel bar or steel plate. Similarly, the lateral frame members 50 and 56 can also be formed of tubular members and extend into one or more lateral openings formed in the corresponding outriggers 20, 22 and are welded around one or both openings thereto, thereby forming a rigid frame.

[0099] For example, the hanging members 46 and 58 can be formed of a closed tubular member or a solid plate. The closed tubular member can be formed of, for example, structural channel members or two stamped plates joined together by welding. For example, each plate can be stamped into a channel cross-section and then joined together in a face-to-face relationship (with the open sides facing each other, in a clamshell arrangement). Optionally, the two plates can be slightly nested to allow the flange of one channel member to be inserted into the open face of the other channel plate and then welded in place along their length by spot welding or continuous welding. Optionally, the plates can be sized such that their flanges are adjacent to each other and also welded together (e.g., by spot welding or continuous welding along their length).

[0100] In addition to increasing the strength and torsional resistance of the lifting legs, their structure also allows for customization of the leg shape. For example, instead of having to, as Figure 9A shown, provide a longer pin 26b on the pivot connection 26 to span the space between the leg 20 and the base (12), the lower portion of the leg 20 (e.g., the hanging member 46) can be formed such that they are offset outwardly or angled outwardly. For example, starting below the pivot connection 30, the lower portion of the leg 20 (e.g., the hanging member 46) can be formed to be offset outwardly or angled outwardly so as to offset the mounting member 26a for the pivot connection 26 on the leg 20 and can be aligned in the same plane as the mounting member 28a for the pivot connection 28. In this way, the pivot connections 26 and 28 can be mounted in the same slot (slot 12c of the frame member 12a). Thus, a single tube weldment can be used to form the base 12.

[0101] On the other hand, the transverse member 44 can be formed of an open cross-section member (e.g., a channel member, including a channel formed of a stamped plate or a structural channel member).

[0102] As described above, the track 42 can be formed of plates, which can be reinforced with struts 48h ( Figure 9A ). Similarly, the linkages 38, 40, and the crank arm 32 can also be formed of plates; and, when needed, bosses or protrusions are provided around their mounting openings to increase their strength. For example, referring to Figure 12E , each linkage 40 can be formed of an elongated rectangular plate. The rectangular plate has a protrusion 40b to reinforce the plate. Similarly, the crank arm 32 ( Figure 12C ) can be formed of a generally triangular plate and includes a protrusion 32b to reinforce the crank arm.

[0103] Referring to Figure 12B, the connecting rod 38 may be formed by two plates 38b. The two plates 38b are connected at their (e.g., lower) edges by a transverse plate 38c. The transverse plate 38c may be welded to the plates 38b or formed integrally with the plates 38b to form a U-shaped connecting assembly. The opening 38a may be reinforced by a boss or flange 38a' surrounding the opening 38a, and the boss or flange 38a' also forms a support surface for the pin 36c of the actuator 36. As described above, the opening 38a may also be elongated to allow unloading from the actuator 36 (e.g., when the lifting assembly 18a is fully lowered).

[0104] Additionally, as shown in the illustrated embodiment, the cross-sections of the components of the lifting assembly may vary along their lengths to provide enhanced strength where needed, but reduce the cross-section where the load on the lifting assembly is reduced, thereby providing a more compact and lighter assembly. Additionally, by varying the cross-section, the components of the lifting assembly may provide a better nesting arrangement when folded. In the illustrated embodiment, the frame member 46 is formed with three different cross-sections at three different heights, which allows the lifting leg 20 to avoid interference with other components of the bed (including the leg 22) as it swings throughout its range of motion.

[0105] For example, referring to Figure 9A , assuming that the force to raise or lower the frame 14 is greatest at the upper end of the leg 20, the upper end of the leg 20 (e.g., the overhanging frame member 46) may have the largest cross-section. Additionally, as the cross-section increases, a portion of the frame member 46 may have an opening portion at its upper end to provide a cable route through the lifting assembly and further provide better nesting. As best understood from Figure 1A , when the lifting assembly is fully folded and the frame 14 is lowered, the mounting bracket 14c and the mounting block 14d may extend into and nest within the opening portion of the upper part of the frame member 46, which again helps to reduce the overall height of the platform when the lift assembly is in its lowest configuration.

[0106] As described above, the lower ends of the lifting legs 20, 22 are mounted to the base 12 by pivot connections 26, 28. As Figure 9 shown, the pivot connection 26 may be formed by a slider 60. The slider 60 is rotatably mounted to each lower end of the lifting leg 20 by a pin 26b. The block 60 is guided in a channel 12c formed in the base frame member 12a ( Figure 2 and 4 ) between the upper and lower flanges 12b. Similarly, the pivot connection 28 may be formed by a slider 64. The slider 64 is rotatably mounted to each lower end of the lifting leg 20 by a pin 28b. The block 64 is positioned and fixed in the channel 12c by a fastener 65 that extends through an opening in the upper flange 12c of the frame member 12a.

[0107] To make the lifting assembly more compact, blocks 60 and 64 can be mounted to pins 26b, 28b without using fasteners or spring clips, but rather are held on pins 26b and 28b using the tab and slot structure of blocks 60 and 64 respectively, which will be described below with reference to Figure 10 , 10A , 10B, and 10C. Additionally, to prevent blocks 60, 64 from rotating off pins 26b, 28b, each block has a protruding connection for mounting 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 in order to mount the block or remove the block from the pin. Additionally, with reference to Figure 3 and 10 , each mounting block is square or rectangular such that they can be held between the upper and lower flanges 12b of frame member 12a and do not rotate, although pins 26b and 28b are free to rotate within the blocks. The tabs (and corresponding notches) on the pins are arranged such that they do not align during normal movement of the lifting mechanism and thus hold the respective blocks on pins (26b, 28b) during normal operation.

[0108] As Figure 10A and 10B best shown, block 60 has a rectangular body 60a with a central transverse opening 60b that includes one or more notches 60c. In the illustrated embodiment, opening 60b includes a pair of opposing notches. Similarly, pin 26b has one or more tabs 26c for alignment with one or more notches. When so aligned, pin 26b can be inserted into opening 60b of block 60, and then block 60 is rotated about the pin, thereby holding the pin on the block. The block is then inserted into frame member 12a (through the cutout or notch 12e described below) and is captured between the upper and lower flanges. Optionally, the upper and lower flanges can each include downwardly and upwardly extending lips 12b' ( Figure 10 and 10A ) to further assist in holding blocks 60 and 64 in slot 12c.

[0109] As Figure 10CAs best shown, block 64 similarly has a rectangular body 64a with a central transverse opening 64b that includes one or more notches 64c. In the illustrated embodiment, opening 64b includes a pair of opposing notches 64c. Similarly, pin 28b has one or more tabs 28c for alignment with one or more of the notches. When so aligned, pin 28b can be inserted into opening 64b of block 64, and then block 64 is rotated about the pin, thereby retaining the pin on the block. Subsequently, the block is inserted into frame member 12a (through a cutout or notch 12e described below) and captured between upper and lower flanges 12b. To fix block 64 in a fixed position, block 64 includes a transverse opening through body 64a and a biasing portion 64d. Biasing portion 64d is curved and aligned with the transverse opening for receiving a fastener 65 through body 64a to fix the position of pivot connection 28 along frame member 12a of base 12.

[0110] Referring Figure 3 and 10 , blocks 60 and 64 are inserted into slot 12c of frame member 12 through notches 12e formed in upper flange 12b of frame member 12. Notches 12e are positioned offset from pivot connection 28 and from the normal travel of sliding pivot connection 26. Pivot connection 28 is fixed along the longitudinal axis of frame member 12a by a fastener 65 during installation. Once inserted therein, blocks 60, 64 are moved to their use positions and then retained therein by upper and lower flanges 12b and optional lip 12b' of frame member 12a. Thus, base 12 has an installation position for the pivot connection that is offset from its use position.

[0111] In addition to the overall construction, this mounting arrangement and mounting construction allows the lifting assemblies 18a (and 18b) to be mounted as a unit (with the actuators and lines (such as power and / or hydraulic lines and / or pneumatic lines) already assembled in the unit), requiring only insertion of the lifting assemblies into the base and connection to mounting blocks 14d at their upper ends, without the need for additional brackets and fasteners for mounting.

[0112] Additionally, again referring Figure 1C and 4 , when frame 14 is in its lowest position, frame member 14a of frame 14 can rest on base 12, i.e., between base members 12a. Further, lift legs 20, 22 and crank arms 32 are arranged such that they fold into the space defined between base members 12a, with most if not all of legs 20 and actuator 36 located at or below the upper flange of base members 12a ( Figure 8)。In addition, as described above, the pivot connectors 26 and 28 are aligned along the respective base frame members 12a and are in the same plane, and the pivot connector 30 is aligned at or just below the upper flange of the respective frame member 12a.

[0113] In this way, when the lifting assembly 18 is in its lowest configuration, many components of the lifting assembly (lifting legs, crank arms) are lowered into the space defined between or slightly below the base frame members 12a, but with a space S left between them, as described above. In addition, when the lifting assembly 18 is in its lowest configuration, the distance from the top of the platform to the floor can be less than 14", less than 13", and optionally less than 12". Additionally, the space below the base members 12a is sufficient to allow a nightstand or the base of the lifting assembly to extend under the base. For example, the distance from the underside of the base members 12a to the floor is at least 4", at least 5", or between approximately 5" - 6".

[0114] As described above, the second lifting leg 22 has one or more stoppers 22a to provide a stopper for the upper portion of the leg 20 when the leg assembly 21 is fully folded. The stoppers 22a are mounted and arranged to extend into the interior of the leg 22 to provide a support surface for the overhanging frame member 46 of the first lifting leg 20 when the first lifting leg 20 is fully folded.

[0115] In the illustrated embodiment, the stopper 22a is formed by an L-shaped bracket 22b which is mounted, for example by welding, to the inner side 22c of the lifting leg 22. The bracket 22b extends inwards from the inwards-facing side 22d of the leg 22 to contact the downward-facing side of the leg 20 when the leg 20 is folded. One or more rubber buffers 22c ( Figure 11 ) can be mounted on the bracket 22b to reduce noise and absorb some vibration. Since the stopper is located near the pivot connector 28, when folded, the weight of the platform and the frame is substantially directly transmitted through the leg 22 to the base 12.

[0116] Referring to Figure 9A , as described above, an actuator 36 can be installed to reduce the lateral load on the components of the lifting assembly. For example, the pin 36c of the actuator 36 can be mounted in the slot 48a of a plate 48 between the linkages 38 and between a pair of bushings 37e ( Figure 9D)。Optionally, a gap or space is provided between the bushing 37e (e.g., a plastic bushing) and the rod 36a (or between the bushing and the link 48) to provide sufficient clearance to avoid binding, but the clearance provided is small enough to avoid causing lateral loads on the lifting assembly, and more specifically on the track 42 (e.g., to avoid tilting of the actuator relative to the path P1). For example, the clearance on each side can be in the range of 1 / 2 to 1 / 1000 inch. Additionally, to help hold the pins in the slots 48a, each opposite end of the pin 36c can be guided by a rectangular bushing 37f that is taller than the height of the slot 48a such that they straddle the outside of the plate 48. Optionally, springs can be provided in lieu of or in addition to the bushings to help keep the rod 36a aligned along the path P1.

[0117] Referring Figure 1A and 3 , optionally, one or more of the lifting assembly components can include protective and / or aesthetic covers, for example formed of 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. A cover C4 can also be provided to extend over the leg 22. However, it should be understood that for the enclosed structure of many of the lifting assembly components, a cover is not required for the leg assembly of the lifting assembly.

[0118] Although not specifically described for each instance, it should be understood that the structural load-bearing members of the lifting assembly can all be formed of metal (including steel) and can also be stamped, molded, cast, or forged members and assembled by welding. Other members such as mounting blocks or covers can be formed of plastic or other low-friction materials and can be molded.

[0119] Optionally, if not all, at least some of the pivot connections can include a retainer 70 ( Figure 12F ) that makes the pivot connection tamper-proof and optionally non-serviceable. This also makes the lifting assembly connection easy to inspect. Although described in detail with reference to the pivot connection 40a of the link 40, it should be understood that the same or similar details apply to other pivot connections.

[0120] As Figure 12F best shown, the end of the pin 40a' of the pivot connection (40a) extends through an opening provided in the link 40. Optionally, the opening can be reinforced by a raised boss 40c. The retainer 70 is mounted around the opening on the pin 40a'. The retainer 70 is mounted to the distal end of the pin 40a' by a standard hollow rivet 72; the hollow rivet 72 extends through the retainer 70 and through a lateral opening provided in the distal end of the pin 40a'.

[0121] In the illustrated embodiment, the retainer 70 includes a cylindrical body 70a having a closed end 70b. The closed end 70b abuts against the distal end of the pin 40a'. The cylindrical wall 70c of the body 70a is bifurcated to facilitate installation on the end of the pin 40a' such that it can be manually (although tools can also be used) installed on the distal end of the pin 40a'. Optionally, the body 70a includes a flange end 70d that forms an annular support surface 70e. When, for example, the pin 40a' is pulled inwardly as shown and engages the washer W, this annular support surface 70e can provide some thrust load. Thus, the retainer 70 provides a connection that is easy to inspect, is tamper-proof, and may be non-serviceable to ensure proper assembly at the original manufacturing facility. Figure 12F As shown, when the pin 40a' is pulled inwardly and engages the washer W, this annular support surface 70e can provide some thrust load. Thus, the retainer 70 provides a connection that is easy to inspect, is tamper-proof, and may be non-serviceable to ensure proper assembly at the original manufacturing facility.

[0122] It will be appreciated that since the head end and foot end lifting assemblies are independent, they can be moved independently to raise or lower the head end or foot end of the support frame, thereby moving the platform to the head-down foot-up position or the reverse head-down foot-up position (see Figure 1A and 5 ). In addition, the speed of each actuator can be independently controlled. For example, suitable actuators include Linak actuators (such as model LA 40) or llcon actuators. For example, the actuator can include a sensor or magnet to measure the speed of the actuator such that the actuation and speed of each actuator can be independently controlled as described.

[0123] Referring to Figure 9H , in one embodiment of a standard medical bed, when in the lowest position, the force of the actuator can be in the range of approximately 5300 - 5400 N; when in an approximately intermediate position between the lowest positions, the force of the actuator can reach approximately 5700 - 5800 N; then, when in the highest position, the force of the actuator falls back to approximately 3200 - 3300 N. It can be understood that when the lifting assembly is in the lowest position of its most compact state, the maximum force is typically required; however, due to the current arrangement of the linkages and crank arms, when the leg assembly is in its lowest position, it maximizes the force arm. 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 leverage provided by the crank arm decreases until the lifting assembly reaches the intermediate region (approximately 19 - 24 inches from the ground), thereby increasing the force required. As Figure 9H shown, as the lifting assembly continues to rise, the leverage provided by the crank arm further decreases, but the rate of decrease becomes smaller until the lifting assembly is in its uppermost position.

[0124] With the above structure, when the lifting assembly 18 is in its lowest position, the distance from the top of the stretcher bed to the floor can be less than 14", less than 13", and optionally less than 12"; and, the space below the base frame member 12a is unobstructed to allow a nightstand or the base of the lifting assembly to extend beneath the base. For example, the distance from the underside of the base frame member 12a to the floor is at least 4", at least 5", or between approximately 5" - 6"; and, a minimum clearance of approximately 2 to 3 inches or approximately 2.4 inches is provided below the lowermost member of the patient support. Additionally, when the lifting assembly is in its raised position, the lifting legs move outward towards the ends of the frame, thus leaving sufficient space to allow a fluoroscopic device to extend between the frame and the base.

[0125] Although not described in every case, it should be understood that the structural components of the frame, platform, and lifting assembly can be formed of metal structural members (such as steel), which are either welded (as described in some cases) or fastened together, for example, by bolts, rivets, pins, or screws, or simply mechanically interlocked (as described above with reference to some brackets). Additionally, the features of one embodiment can be combined with the features of another or more embodiments. Furthermore, it should be understood that the actuators can be controlled to extend or contract independently, for example, such that they can raise or lower one end of the patient support device to orient the patient support device platform in a Trendelenburg or reverse Trendelenburg position.

[0126] Directional terms, such as "vertical", "horizontal", "top", "bottom", "upper", "lower", "inner", "inward", "outer", and "outward", are used to assist in describing the present invention based on the orientation of the embodiments shown in the drawings. The use of directional terms should not be construed as limiting the present invention to any one or more specific orientations.

[0127] Various changes and alterations may be made to the above embodiments without departing from the spirit and broader aspects of the disclosure as defined in the appended claims, which will be interpreted in accordance with the principles of patent law including the doctrine of equivalents. The present disclosure is presented for purposes of illustration and should not be construed as an exhaustive description of all embodiments of the present disclosure or as limiting the scope of the claims to the specific elements illustrated or described in connection with these embodiments. For example, but not limited to, any single element of the disclosed subject matter may be replaced by an alternative element that provides substantially similar functionality or otherwise provides adequate operation. This includes, for example, alternative elements that are currently known, such as elements that may currently be known to those skilled in the art, and alternative elements that may be developed in the future, such as elements that may be considered alternatives by those skilled in the art at the time of development. Additionally, the disclosed embodiments include a plurality of features that are consistently described and that may cooperate to provide a series of benefits. The present disclosure is not limited to those embodiments that include all of these features or provide all of the stated benefits, unless expressly set forth otherwise in the issued claims. Any reference to an element of a claim in the singular, such as the use of the articles "a," "an," "the," or "said," should not be construed as limiting the element to the singular.

Claims

1. Patient support device, comprising: Base; A frame supported relative to the base, the frame being configured to support a platform for supporting a patient thereon; A lifting assembly for raising or lowering the frame relative to the base and pivotally coupled to the frame at its upper end and pivotally coupled to the base at its lower end; The lifting assembly includes a first leg and a second leg, the second leg being pivotally mounted to the first leg at an intermediate portion of the first leg to form an inverted Y-shaped leg assembly when deployed, the first leg including a first slot and a second slot, the second slot being connected to the second leg by a sliding pivot connection; and, An actuator mounted in the lifting assembly, the actuator being located between a first pivot connection of the first leg and the first slot, the actuator, the first slot, and the second slot providing a mounting configuration to generate a maximum force F1 when raising the frame after the lifting assembly has been raised from its lowest configuration, a minimum force F2 when lowering or raising the frame after the lifting assembly has been raised from the lowest configuration, and an initial force SF at the lowest configuration that is less than the maximum force F1, and wherein the minimum force F2 is in the range of 50% to 70% of the maximum force F1.

2. The patient support device according to claim 1, wherein, The maximum force F1 is generated before reaching the mid-stroke of the lifting assembly.

3. The patient support device according to claim 1 or 2, wherein, The actuator is mounted in the lifting assembly with a mounting configuration to generate the initial force SF; wherein the initial force SF is in the range of 95% to 99% of the maximum force F1.

4. The patient support device according to claim 1 or 2, wherein, The actuator is mounted in the lifting assembly with a mounting configuration to generate the initial force SF; wherein the initial force SF is approximately 97% of the maximum force F1.

5. The patient support device according to claim 1 or 2, wherein, The actuator mounting configuration is to generate the minimum force F2 when raising or lowering the frame, wherein the minimum force F2 is approximately 60% of the maximum force F1.

6. The patient support device according to claim 1, wherein the second slot includes a non-linear path that guides the sliding pivot connection of the second leg.

7. The patient support device according to claim 1, wherein the actuator is coupled to the first slot through a second sliding pivot connection.

8. The patient support device according to claim 7, wherein the second sliding pivot connection is connected to the sliding pivot connection through a connecting rod, wherein the actuator is connected to the sliding pivot connection through the connecting rod, and wherein the movement of the second sliding pivot connection along the first slot is converted into the movement of the sliding pivot connection along the second slot.

9. Patient support device, comprising: Base; A frame supported relative to the base, the frame being configured to support a platform for supporting a patient thereon; A lifting assembly for raising or lowering the frame relative to the base and pivotally coupled to the frame at its upper end and pivotally coupled to the base at its lower end; The lifting assembly includes a first leg and a second leg, the second leg being pivotally mounted to the first leg at an intermediate portion of the first leg to form an inverted Y-shaped leg assembly when deployed, the first leg including a first slot and a second slot, the second slot being connected to the second leg by a sliding pivot connection; and, An actuator mounted in the leg assembly, the actuator being located between a first pivot connection of the first leg and the first slot, the actuator, the first slot, and the second slot providing a mounting configuration to generate a maximum force F1, a minimum force F2 when raising or lowering the frame, and an initial force SF, wherein the initial force SF is generated at the lowest configuration of the lifting assembly, the initial force is less than the maximum force F1, and the minimum force F2 is in the range of 55% to 65% of the maximum force F1.

10. The patient support device according to claim 9, wherein, The minimum force F2 is generated at the maximum height of the lifting assembly.

11. The patient support device according to claim 9 or 10, wherein, The minimum force F2 is in the range of 55% to 65% of the starting force SF.

12. Patient support device, comprising: Base; A frame supported relative to the base, the frame being configured to support a platform for supporting a patient thereon; A lifting assembly for raising or lowering the frame relative to the base and pivotally coupled to the frame at its upper end and pivotally coupled to the base at its lower end; Actuator; The lifting assembly includes a first leg and a second leg, the second leg being pivotally mounted to the first leg at an intermediate portion of the first leg about a folding pivot to form an inverted Y-shaped leg assembly when deployed, the Y-shaped leg assembly including a first slot and a second slot fixed relative to the first leg and moving with the first leg; The actuator is mounted in the lifting assembly between a first pivot connection of the first leg and a first sliding pivot connection of the first leg, the actuator being coupled to a second sliding pivot connection via the first sliding pivot connection, the first sliding pivot connection being guided by the first slot of the Y-shaped leg assembly, and the second sliding pivot connection being guided by the second slot of the Y-shaped leg assembly; and, The second sliding pivot connection is connected to the second leg, wherein when the actuator extends or contracts, the first leg and the second leg deploy or fold relative to each other.

13. The patient support device according to claim 12, wherein, The first leg includes an upper pivot connection connected to the frame and a lower pivot connection connected to the base; and further includes a connecting rod, the connecting rod being slidably coupled to the first leg at the second sliding pivot connection and eccentrically coupled to the second leg by a crank arm.

14. The patient support device according to claim 13, wherein, The second sliding pivot connection between the connecting rod and the first leg includes a non-linear sliding pivot connection guided by the second slot.

15. The patient support device according to claim 13, wherein, The first leg includes a lower pivot connection, and when the lifting assembly is in its lowest position, the second sliding pivot connection between the connecting rod and the first leg extends below the lower pivot connection of the first leg.

16. A patient support device, comprising: Base; A frame supported relative to the base, the frame being configured to support a platform for supporting a patient thereon; A lifting assembly for raising or lowering the frame relative to the base and pivotally coupled to the frame at its upper end and pivotally coupled to the base at its lower end; Actuator, the actuator having a base and a telescopic rod; The lifting assembly includes a first leg and a second leg, the second leg being pivotally mounted to the first leg at an intermediate portion of the first leg to form an inverted Y-shaped leg assembly when deployed, the first leg including a first slot and a second slot; The second leg has a crank arm; and, A first link having a first end and a second end, the first end of the first link being coupled to the crank arm, the first link being slidably coupled to the first leg by a first sliding pivot connection and pivotally coupled to the crank arm, the first sliding pivot connection being guided by a first slot of the first leg, and A second link having a first end and a second end, the first end of the second link being pivotally coupled to the telescopic rod of the actuator and being slidably coupled to the first leg by a second sliding pivot connection, the second sliding pivot connection being guided by a second slot of the first leg, and the second end of the second link being pivotally coupled to the second end of the first link by the first sliding pivot connection, the second link being configured to apply a force to the crank arm through the first link, the first link being configured to move along a non-linear path so as to push or pull the crank arm from a certain angular range, and thereby cause the first leg and the second leg to unfold or fold relative to each other to extend or contract the lifting assembly.

17. The patient support device according to claim 16, wherein, The first leg includes an upper pivot connection connected to the frame and a lower pivot connection connected to the base.

18. The patient support device according to claim 17, wherein, The first sliding pivot connection includes a non-linear sliding pivot connection.

19. A patient support device, comprising: A base; A frame supported relative to the base, the frame being configured to support a platform for supporting a patient thereon; A head-end actuator; A foot-end actuator; And, A lifting assembly for raising or lowering the frame relative to the base; the lifting assembly includes a head-end leg assembly and a foot-end leg assembly; each leg assembly has a pair of legs, each pair of legs including a first leg and a second leg; the first leg and the second leg form an inverted Y-shaped structure when the frame is raised and fold when the frame is lowered; The inverted Y-shaped structure includes a first slot and a second slot fixed relative to the first leg and moving with the first leg; The first leg is pivotally mounted to the frame at its upper end and pivotally mounted to the base at its lower end; each pair of legs has a folding pivot axis; and Each of the head-end actuator and the foot-end actuator has a pivot connection connected to its corresponding first leg and has a first sliding pivot connection of its corresponding first leg, each of the head-end actuator and the foot-end actuator has a second sliding pivot connection connected to its corresponding second leg through the first sliding pivot connection, each of the first sliding pivot connections being correspondingly guided by the first slot; the second sliding pivot connection has a path guided by the second slot and the path includes a linear portion and a curved portion, and wherein the first leg and the second leg of each leg assembly are connected such that the extension and contraction of their corresponding actuators will unfold or fold the leg assembly to raise or lower the frame.

20. The patient support device according to claim 19, wherein each said first leg is connected to its corresponding second leg by a link, and the link is eccentrically mounted to its corresponding second leg.

21. The patient support device according to claim 20, wherein one end of each said link is coupled to its corresponding first leg by the respective first sliding pivot connector of the first sliding pivot connectors.

22. The patient support device according to claim 21, wherein the actuator has a linear path guided by the first slot with respect to the sliding pivot connection of the first leg.

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