Patent Description:
Patient lift apparatuses are already known in the art and available on the market. Examples thereof include for instance Invacare®'s Reliant™ <NUM> and Roze stand assist products.

International (<CIT> discloses a patient lift apparatus as embodied in the form of Invacare®'s aforementioned Roze product. This known patient lift apparatus comprises a supporting frame, a boom portion connected to the supporting frame via a pivot joint to allow the boom portion to pivot with respect to the supporting frame about a pivot axis, and a boom actuator to mechanically assist pivotal movement of the boom portion with respect to the supporting frame. A distal end of the boom portion is configured to include hook portions configured to allow attachment of a sling for holding and supporting a patient during lifting and transfer. Handle portions are furthermore provided on the boom portions to provide the patient with the option of a manual grip helping stabilization during patient lifting and transfer. This patient lift apparatus further comprises a leg/knee support (or "leg/knee pad") and a foot support (or "foot plate"), both connected to the supporting frame. According to <CIT>, the leg/knee support is configured to be adjustable in height to adjust the position thereof to different needs and patient morphologies. More precisely, the leg/knee support is mounted on a vertical guide and rail mechanism configured to allow positioning of the leg/knee support at any desired vertical position.

According to <CIT>, the length of the boom portion is fixed and not adjustable. Patient lift apparatuses of the type comprising a length-adjustable boom portion are however known in the art.

US Patent No. <CIT> for instance discloses a patient lift apparatus where the boom portion is configured as a telescopic arm comprising an outer member and an inner member that is telescopically received inside the outer member to allow displacement of the inner member with respect to the outer member and adjustment of an effective length of the telescopic arm.

US Patent Publication No. <CIT> similarly discloses a patient lift apparatus of the type comprising a boom portion that is configured as a telescopic arm. In this particular instance, a simple pin-and-hole arrangement is provided to allow adjustment of the inner member of the telescopic arm at any desired one of a plurality of predefined longitudinal positions with respect to the outer member.

European Patent Publication No. <CIT> discloses yet another example of a patient lift apparatus of the type comprising a boom portion that is configured as a telescopic arm.

The solutions disclosed in <CIT>, <CIT> and <CIT> are useful in allowing adjustment of the patient lift apparatus to the actual size of each patient and to adjust the lifting amplitude to match the relevant need. Such solutions are not however entirely satisfactory from the point of view of the adjustability of the effective length of the boom portion. Furthermore, the necessary clearance, or play, between the inner and outer members of the telescopic arm may be to the detriment of comfort for the patient as the inner member may move under load within the space provided inside the outer member, leading to undesired and unpleasant movement for the patient during lifting and/or transfer.

International (<CIT> discloses a patient lift apparatus similar to that of <CIT> where the leg/knee support is additionally configured to be releasable from the supporting frame. In this particular instance, the leg/knee support can be adjusted in height and potentially be released by actuating a simple thumbscrew.

According to <CIT>, the guide and rail mechanism includes a guide portion that forms an integral part of the supporting frame and of the locking/unlocking arrangement used to secure the leg/knee support to the supporting frame. More specifically, the guide portion is affixed to an accessory frame portion, or support mount, extending from the supporting frame, and the leg/knee support can be selectively released from the supporting mount by means of release handle provided on the guide portion. The leg/knee support of <CIT> merely comprises a rail portion that is slidably guided inside the guide portion and selectively lockable in position by means of the locking/unlocking arrangement. Furthermore, the leg/knee support of <CIT> includes a handle, but this handle has no particular locking or unlocking function. As simpler, better integrated solution is therefore desirable.

Swiss Patent Publication No. <CIT> discloses a patient lift apparatus of the type comprising a pair of leg/knee supports mounted on a vertically-adjustable support that is guided along the support frame of the patient lift apparatus. Each leg/knee support is mounted on the vertically-adjustable support by means of a guide member that can be locked onto or released from an associated L-shaped support member by actuating a simple thumbscrew/handscrew.

British Patent Publication <CIT> discloses yet another patient lift apparatus comprising a leg/knee support than can potentially be released from the supporting frame of the patient lift apparatus by actuating a retractable locking pin that is configured to cooperate with any one of a plurality of indexing holes (or indents) formed on an arm attached to a read portion of the leg/knee support. According to <CIT>, the retractable locking pin does not form part of the leg/knee support per se, but is provided on a support mount that is secured to the supporting frame.

International (<CIT> discloses a patient lift apparatus where the leg/knee support is adapted to pivot about a pivot axis and thereby follow movement of the patient's legs/knees upon standing or sitting.

Dutch Patent No. <CIT> similarly discloses a patient lift apparatus comprising a leg/knee support that can be pivoted about a pivot axis. In this particular instance, electric motors are provided to cause pivotal movement of the leg/knee support.

The aforementioned known solutions are not fully satisfactory, and there remains a need for an improved solution.

A general aim of the invention is to provide an improved patient lift apparatus.

More specifically, an aim of the present invention is to provide such a patient lift apparatus of the type comprising a leg/knee support, which patient lift apparatus does not suffer from the shortcomings of the above-mentioned known solutions.

Yet another aim of the invention is to provide such a solution which is both robust and easy to handle and operate for the patient and caregiver.

A further aim of the invention is to provide such a solution which provides greater comfort for the patient during assisted transfer in the area of the leg/knee support.

Still another aim of the invention is to provide such a solution that is particularly suited to act as stand assist hoist for the purpose of transferring patients from a seated position to a standing position, and vice versa, with improved adjustability to the patient's needs and morphology.

These aims are achieved thanks to the solutions defined in the claims.

In accordance with the invention, there is provided a patient lift apparatus according to claim <NUM>, namely a patient lift apparatus comprising a supporting frame, a boom portion connected to the supporting frame via a pivot joint to allow the boom portion to pivot with respect to the supporting frame about a pivot axis, a boom actuator to mechanically assist pivotal movement of the boom portion with respect to the supporting frame, and a leg/knee support connected to the supporting frame. According to the invention, the leg/knee support comprises:.

By way of preference, a pair of said spring elements may be provided, which pair of spring elements is configured to bring the outer casing to the default position, which default position is a median position between two extreme, tilted positions. Each spring element is attached to a corresponding spring mount provided on the outer casing, which spring mount may further act as stop element limiting pivotal movement of the outer casing about the pivot axis.

Each spring element may in particular be a tension spring.

According to a further embodiment of the invention, a total amplitude of pivoting movement of the leg/knee support with respect to the support mount is preferably of the order of <NUM> to <NUM> degrees.

The boom portion may advantageously be configured as a telescopic arm comprising an outer member and an inner member that is telescopically received inside the outer member to allow displacement of the inner member with respect to the outer member and adjustment of an effective length of the telescopic arm. In this context, the patient lift apparatus preferably further comprises an indexing mechanism configured to allow positioning of the inner member at a plurality of predefined longitudinal positions with respect to the outer member.

Further advantageous embodiments of the invention are discussed below.

Other features and advantages of the present invention will appear more clearly from reading the following detailed description of embodiments of the invention which are presented solely by way of non-restrictive examples and illustrated by the attached drawings in which:.

The present invention will be described in relation to various illustrative embodiments. It shall be understood that the scope of the invention encompasses all combinations and sub-combinations of the features of the embodiments disclosed herein.

As described herein, when two or more parts or components are described as being connected, secured or coupled to one another, they can be so connected, secured or coupled directly to each other or through one or more intermediary parts.

The invention will be described in relation to various embodiments of a patient lift apparatus, as depicted in <FIG>. The patient lift apparatus shown in <FIG> and <FIG> is generally designated by reference numeral <NUM> and is especially designed to act as stand-assist hoist for the purpose of transferring patients from a seated position to a standing position, and vice versa.

Referring to <FIG> and <FIG>, there is shown a perspective view and a side view, respectively, of the patient lift apparatus <NUM>, which apparatus <NUM> includes a supporting frame <NUM> comprising a base member <NUM>, a mast <NUM> and a pair of supporting legs <NUM> provided at their ends with casters <NUM>. An opening angle of the supporting legs <NUM> is advantageously adjustable by means of an adjustment device located on a rear end of the patient lift apparatus <NUM>, as is known in the art. A suitable steering handle <NUM> is provided on the mast <NUM> to allow a caregiver to move and position the apparatus <NUM> according to the needs.

A boom portion <NUM> is connected to the supporting frame <NUM>, namely to mast <NUM>, via a pivot joint PJ1 thereby allowing the boom portion <NUM> to pivot with respect to the mast <NUM> about a pivot axis PA1. Pivot axis PA1 is understood to extend essentially parallel to a horizontal plane in the illustrated example. A boom actuator <NUM> is further provided to mechanically assist pivotal movement of the boom portion <NUM> with respect to the mast <NUM>, which boom actuator <NUM> is mounted, at a lower end, on a mast extension 12A extending away from the mast <NUM>. An upper end of the boom actuator <NUM>, designated by reference sign 15A, is connected to the boom portion <NUM>, namely via a mounting bracket <NUM> located on a lower portion of the boom portion <NUM>. The boom actuator <NUM> can for instance be an electrically driven screw-type, hydraulic or pneumatic actuator, as is known in the art.

At a distal end of the boom portion <NUM>, the boom portion <NUM> is here configured to exhibit a pair of arms, forming an integral part of the boom portion <NUM>, each arm comprising a handle portion <NUM> shaped to provide a manual grip for the patient. Also provided on each arm is at least one hook portion <NUM> for attachment of a sling (not shown).

In the illustrated example, the boom portion <NUM> is configured as a telescopic arm <NUM> comprising (see especially <FIG> and <FIG>) an outer member <NUM> and an inner member <NUM> that is telescopically received inside the outer member <NUM> to allow displacement of the inner member <NUM> with respect to the outer member <NUM> and adjustment of an effective length of the telescopic arm <NUM>, as schematically illustrated by the double arrow in <FIG> (see also <FIG>).

As for instance illustrated by <FIG>, the patient lift apparatus <NUM> further comprises a centering system, which centering system is configured to center the inner member <NUM> with respect to the outer member <NUM> and reduce or suppress a clearance between the inner member <NUM> and the outer member <NUM>. A particularly advantageous embodiment of this centering system is shown in <FIG> (see also <FIG>), and generally designated by reference numeral <NUM>, which centering system <NUM> will be described in greater detail hereafter.

In accordance with another embodiment of the invention, the patient lift apparatus <NUM> further comprises an indexing mechanism configured to allow positioning of the inner member <NUM> at a plurality of predefined longitudinal positions with respect to the outer member <NUM>. A particularly advantageous embodiment of this indexing system is shown in <FIG>, as well as partly visible in <FIG>, <FIG> and <FIG>, and generally designated by reference numeral <NUM>, which indexing mechanism <NUM> will be described in greater detail hereafter.

Also visible in <FIG> and <FIG> is a leg/knee support (or "leg/knee pad") <NUM> connected to the supporting frame <NUM>, which leg/knee support <NUM> is shaped and advantageously padded to provide support for the patient's legs or knees during transfer of the patient from a seated position to a standing position, and vice versa. The leg/knee support <NUM> is also shown in greater detail on <FIG>, reference sign 500A designating two support surfaces extending laterally for supporting the patient's legs/knees. The leg/knee support <NUM> is connected to the supporting frame <NUM>, namely to the mast <NUM>, via the aforementioned mast extension 12A. Also shown in <FIG> and <FIG> is an optional foot support (or "foot plate") <NUM>, which foot support <NUM> is configured to receive the patient's feet. The leg/knee support <NUM> is preferably configured to be selectively releasable from the supporting frame <NUM>. The foot support <NUM> may likewise be configured to be selectively releasable from the supporting frame <NUM>.

A support mount <NUM> is provided on the supporting frame <NUM>, namely at a distal end of the mast extension 12A, to secure the leg/knee support <NUM> onto the supporting frame. Part of this support mount <NUM> is visible on <FIG> and <FIG>. In the illustrated embodiment, upon being released, the leg/knee support <NUM> can be removed from the support mount <NUM> by sliding the leg/knee support <NUM> upward along the support mount <NUM>, the support mount <NUM> acting as a guide. <FIG> illustrates the support mount <NUM>, without the leg/knee support <NUM> connected thereto.

<FIG> is an enlarged partial side view of a cross-section of the telescopic arm <NUM> of the patient lift apparatus <NUM> of <FIG> showing a particularly preferred embodiment of the indexing mechanism <NUM>. In accordance with this preferred embodiment, the indexing mechanism <NUM> comprises a releasable indexing plunger <NUM> mounted on the outer member <NUM> and having a retractable end portion 210A configured to engage with any selected positioning hole among a plurality of positioning holes 182A that are distributed longitudinally along a portion of the inner member <NUM>. <FIG> shows the retractable end portion 210A engaged with the second positioning hole 182A provided on the inner member <NUM> starting from the right. Eight positioning holes 182A are visible in <FIG>, but it should be appreciated that any number of positioning holes 182A could be provided. The actual number of positioning holes 182A, and the distribution thereof along the length of the inner member <NUM>, will be determined according to the needs, especially the desired overall amplitude of adjustment of the effective length of the telescopic arm <NUM> and the amplitude of each individual adjustment step.

As illustrated, the indexing mechanism <NUM> further comprises a manually-operable release lever <NUM> that is mechanically linked to the releasable indexing plunger <NUM> to selectively allow retraction of the retractable end portion 210A of the indexing plunger <NUM> out of engagement with the selected positioning hole 182A, thereby releasing the inner member <NUM> and allowing repositioning thereof with respect to the outer member <NUM> at a different one of the predefined longitudinal positions. <FIG> shows the retractable end portion 210A retracted out of engagement from the positioning hole 182A. In the illustrated embodiment, one end 250A of the manually-operable release lever <NUM> is coupled to the releasable indexing plunger <NUM> and an intermediate portion of the manually-operable release lever <NUM> is configured to act as a pivot 250B about which the manually-operable lever <NUM> can pivot, upon being manually operated, as illustrated by <FIG>, to cause retraction of the retractable end portion 210A of the indexing plunger <NUM>. The relevant pivot axis of the manually-operable lever <NUM> is shown in <FIG> and designated by reference sign PA2.

By way of preference, the indexing mechanism <NUM> is located on a lower portion of the outer member <NUM>. In that respect, in the illustrated embodiment, the release lever <NUM> is pivotably supported onto the same mounting bracket <NUM> as the upper end 15A of the boom actuator <NUM>, which leads to a particularly simple and elegant integration of the indexing mechanism <NUM>. In that context, it is advantageous, for safety purposes, to additionally provide a cover element <NUM> located on the mounting bracket <NUM>, as shown in <FIG> (see also <FIG>), to cover part of the indexing mechanism <NUM>, namely the indexing plunger <NUM> and the end 250A of the release lever <NUM>, and thereby prevent finger or hand entrapment.

The releasable indexing plunger <NUM> is preferably a spring-loaded indexing plunger whose retractable end portion 210A is configured to be urged towards an inner side of the outer member <NUM> and to automatically engage with any one of the plurality of positioning holes 182A provided on the inner member <NUM> upon alignment therewith.

In the illustrated example, disengagement of the retractable end portion 210A of the releasable indexing plunger <NUM> is caused by a slight pivoting movement of the release lever <NUM> about the pivot axis PA2, namely in a counter-clockwise direction in the illustration of <FIG> (as schematically illustrated by the curved arrow), i.e. by pressing the free end of the release lever <NUM> upward towards the outer member <NUM>.

<FIG> is an enlarged partial perspective view of a section of the telescopic arm <NUM> of the patient lift apparatus <NUM> of <FIG> showing a particularly preferred embodiment of the centering system <NUM>. This centering system <NUM> is also visible in <FIG>. Part of the outer member <NUM> has been omitted in the illustration of <FIG> for the purpose of explanation. According to this particularly preferred embodiment, the centering system <NUM> includes a first centering element, designated by reference numeral <NUM>, mounted on the outer member <NUM> and interposed between an inner side 181A of the outer member <NUM> and an outer periphery 182B of the inner member <NUM>. The centering system <NUM> further comprises a second centering element, designated by reference numeral <NUM>, mounted on the inner member <NUM> and guided inside the outer member <NUM>. In the illustrated embodiment, the first and second centering elements <NUM>, <NUM> are configured to suppress the clearance between the outer member <NUM> and the inner member <NUM>. The provision of the first and second centering elements <NUM>, <NUM> is advantageous in that the centering elements <NUM>, <NUM> can be designed to have better dimensional tolerances than that of the inner and outer member <NUM>, <NUM>, thereby eliminating play in the telescopic arm <NUM>.

By way of preference, the first centering element is configured as a bushing member <NUM> mounted on a distal end portion of the outer member <NUM>. A portion 310A, 310B of this bushing member <NUM> extends between the inner side 181A of the outer member <NUM> and the outer periphery 182B of the inner member <NUM>, as this is visible in <FIG>. <FIG> shows the bushing member <NUM> with the outer member <NUM> being entirely omitted for the purpose of explanation. The second centering element is configured as a guiding member <NUM> mounted on a distal end portion of the inner member <NUM> and guided inside the outer member <NUM>, as likewise shown in <FIG>. Guide surfaces 320A are provided on the periphery of the guide member <NUM> for guidance against the inner side 181A of the outer member <NUM>.

Preferably, the bushing member <NUM> comprises a plurality of extensions 310A extending longitudinally between the inner side 181A of the outer member <NUM> and the outer periphery 182B of the inner member <NUM> and a plurality of flat spring elements <NUM> located on said extensions 310A. A total of eight such extensions 310A and flat spring elements <NUM> are provided in the illustrated example, disposed in pairs along each of four sides, but it should be appreciated that any number of extensions and spring elements, and geometry, could be contemplated. In the illustrated example, the flat spring elements <NUM> are interposed between the inner side 181A of the outer member <NUM> and the extensions 310A to press these extensions 310A inwardly towards the outer periphery of the inner member <NUM> (see also <FIG>), thereby suppressing any play between the outer and inner members <NUM>, <NUM>.

Reference sign 310B in <FIG> designates a further extension provided on each lateral side of the bushing member <NUM> to secure the bushing member <NUM> to the distal end of the outer member <NUM>. This extension 310B is provided with a locking tab designed to engage with a corresponding mounting aperture provided on the outer member <NUM> (which mounting aperture is visible on <FIG>, <FIG> and <FIG>).

By way of preference, the centering system <NUM>, which is mounted on the outer member <NUM> and the inner member <NUM>, is configured such as not to interfere with operation of the releasable indexing plunger <NUM> of the aforementioned indexing mechanism <NUM>.

The aforementioned solution to suppress the clearance between the outer and inner members <NUM>, <NUM> of the telescopic arm <NUM> is particularly simple and robust. Other solutions could however be contemplated to reduce or suppress the clearance between the outer and inner members <NUM>, <NUM>, including solutions making use of e.g. an adjustable mechanism or an articulated linkage mounted on the inner member <NUM> and configured to translate a longitudinal displacement of a movable adjustment member into a radial displacement of two or more centering elements cooperating with the inner side 181A of the outer member <NUM>. Similarly, centering of the inner member <NUM> with respect to the outer member <NUM> could also be performed by means of a radially-adjustable mandrel device mounted within the inner member <NUM> and projecting through the inner member <NUM> toward the inner side 181A of the outer member <NUM>.

Turning now to <FIG> and <FIG>, there is shown a particularly preferred embodiment of the leg/knee support <NUM>. As this has already been mentioned, the leg/knee support <NUM> is configured to be selectively releasable from the supporting frame <NUM>. As illustrated in <FIG>, the leg/knee support <NUM> advantageously comprises a manually-operable release mechanism forming an integral part of the leg/knee support <NUM>, which manually-operable release mechanism is configured to allow selective release of the leg/knee support <NUM> from the supporting frame <NUM>. This manually-operable release mechanism comprises a retaining device <NUM> configured to cooperate with the support mount <NUM> provided on the supporting frame <NUM>, namely at a distal end of the mast extension 12A, as again illustrated in <FIG>. The manually-operable release mechanism further comprises a manually-operable handle <NUM> that cooperates with the retaining device <NUM> to allow selective release of the retaining device <NUM> from the support mount <NUM> and thereby allow removal of the leg/knee support <NUM> from the supporting frame <NUM>.

As illustrated in <FIG>, the retaining device <NUM> may in particular comprise first and second retaining members 51A, 51B forming a spacing therebetween and which are configured to act as a guide dimensioned to receive the support mount <NUM> (see also <FIG> and <FIG>). More specifically, the first and second retaining members 51A, 51B are designed in such a way that the leg/knee support <NUM> can be slid onto the support mount <NUM>, engagement and disengagement of the leg/knee support <NUM> occurring in the illustrated embodiment along a substantially vertical direction.

By way of preference, the manually-operable handle <NUM> is configured as a sliding handle provided on top of the leg/knee support <NUM>, the handle <NUM> being guided by and allowed to translate within an upper portion of an outer casing <NUM> of the leg/knee support <NUM>.

Translation of the movement of the manually-operable handle <NUM> into a release action of the retaining device <NUM> (as will be explained hereafter) can be carried out in different ways. One solution may consist in connecting the handle directly to the relevant retaining device or via an articulated linkage. A particularly simple and robust solution may consist, as illustrated in <FIG>, in coupling the handle <NUM> to the retaining device <NUM> via a cable <NUM>. In <FIG>, reference sign 52A designates guide elements guiding the cable <NUM> from the handle <NUM> to the retaining device <NUM>. This solution is particularly simple and provides great freedom for translating the movement of the handle <NUM> into the required release action of the retaining device <NUM>. In the illustrated example, it will be appreciated that movement of the handle <NUM> and the release action of the retaining device <NUM> both occur as translational movements, however along different directions.

In a manner similar to the aforementioned indexing mechanism <NUM>, the retaining device <NUM> comprises a releasable indexing plunger <NUM> having a retractable end portion 510A configured to engage with at least one positioning hole 120A provided on the support mount <NUM>. In the illustrated embodiment, the releasable indexing plunger <NUM> is mounted on the first retaining member 51A and the retractable end portion 510A extends through the spacing formed between the first and second retaining members 51A, 51B towards the second retaining member 51B. In this particular instance, the releasable indexing plunger <NUM> is mechanically coupled to an end of the cable <NUM> to cause retraction of the retractable end portion <NUM> upon actuation of the handle <NUM>.

Only one position hole 120A could be provided for the purpose of securing the leg/knee support <NUM> to the support mount <NUM>. By way of preference, a plurality of positioning holes 120A are distributed along a portion of the support mount <NUM> to allow a vertical adjustment of the leg/knee support <NUM> with respect to the supporting frame <NUM>, as this is visible in <FIG> and 6A-B. In that respect, the retractable end portion 510A of the releasable indexing plunger <NUM> is likewise configured to engage with any selected positioning hole among the plurality of positioning holes 120A to allow adjustment of a vertical position of the leg/knee support <NUM> with respect to the supporting frame <NUM>.

Like the releasable indexing plunger <NUM>, the releasable indexing plunger <NUM> is preferably a spring-loaded indexing plunger whose retractable end portion 510A is configured to be urged towards the support mount <NUM> and to automatically engage with any one of the positioning holes 120A provided on the support mount <NUM> upon alignment therewith.

It will be appreciated that the aforementioned manually-operable release mechanism provides a simple and robust solution ensuring that the leg/knee support <NUM> is adequately secured to the supporting frame <NUM>, while allowing easy and quick removal of the leg/knee support <NUM>, without this requiring any tool.

In accordance with the invention, the leg/knee support <NUM> is configured to be partly pivotable with respect to the support mount <NUM> about a pivot axis, identified in <FIG> and <FIG> by reference sign PA3, and within a defined pivoting range. More specifically, the outer casing <NUM> is configured to be pivotable with respect to the retaining device <NUM> about the pivot axis PA3 and within said defined pivoting range.

In accordance with the invention, at least one spring element <NUM>, <NUM> coupling the outer casing <NUM> to the retaining device <NUM> is provided, which at least one spring element <NUM>, <NUM> is configured to bring the outer casing <NUM> to a default position with respect to the retaining device <NUM> when no external force is applied onto the outer casing <NUM>. By way of preference, as illustrated in <FIG>, a pair of spring elements <NUM>, <NUM> is provided, which pair of spring elements <NUM>, <NUM> is configured to bring the outer casing <NUM> to the default position, which default position is a median position between two extreme tilted positions. Such two extreme tilted positions are illustrated in <FIG> and <FIG>.

More specifically, in the illustrated embodiment, each spring element <NUM>, <NUM> is a tension spring, namely a spring that stretches as load is applied to it. One end of each spring element <NUM>, <NUM> is attached to a corresponding location of the retaining device <NUM> and the other end of each spring element <NUM>, <NUM> is attached to a corresponding spring mount <NUM>, respectively <NUM>, provided on the outer casing <NUM>. As show in <FIG>, the first and second spring elements <NUM>, <NUM> are disposed essentially symmetrically about the pivot axis PA3, meaning that one or the other spring element <NUM>, <NUM> will stretch as the outer casing <NUM> pivots about the pivot axis PA3.

Referring to <FIG>, which shows the leg/knee support <NUM> in a first extreme tilted position where the outer casing <NUM> is pivoted in the clockwise direction about pivot axis PA3, pivotal movement of the outer casing <NUM> causes an extension of the second (lower) spring element <NUM> compared to the default position illustrated in <FIG>. By contrast, the first (upper) spring element <NUM> is relieved from any tension. In this first extreme tilted position the first (upper) spring mount <NUM> comes in abutment with a corresponding section of the retaining device <NUM>, preventing further pivotal movement of the outer casing <NUM> in the clockwise direction. When the external force applied on the outer casing <NUM> is suppressed (namely when the contact with the patient's legs or knees is interrupted), the second spring element <NUM> will automatically pull the outer casing <NUM> to pivot in the counter-clockwise direction and return to the default position.

Referring to <FIG>, which shows the leg/knee support <NUM> in a second extreme tilted position where the outer casing <NUM> is pivoted in the counter-clockwise direction about pivot axis PA3, pivotal movement of the outer casing <NUM> conversely causes an extension of the first (upper) spring element <NUM> compared to the default position illustrated in <FIG>. By contrast, the second (lower) spring element <NUM> is relieved from any tension in this case. In this second extreme tilted position the second (lower) spring mount <NUM> comes in abutment with a corresponding section of the retaining device <NUM>, preventing further pivotal movement of the outer casing <NUM> in the counter-clockwise direction. When the external force applied on the outer casing <NUM> is suppressed (namely when the contact with the patient's legs or knees is interrupted), the first spring element <NUM> will likewise automatically pull the outer casing <NUM> to pivot in the clockwise direction and return to the default position.

One may thus appreciate that, in accordance with this embodiment of the invention, each spring mount <NUM>, <NUM> further acts as stop element limiting pivotal movement of the outer casing <NUM> about the pivot axis PA3. Advantageously, the leg/knee support <NUM> is configured so that a total amplitude of pivoting movement thereof with respect to the support mount <NUM> is of the order of <NUM> to <NUM> degrees. For the sake of illustration, the leg/knee support <NUM> shown in <FIG> and <FIG> is here configured to have a pivoting range of the order of +/- <NUM> degrees about de default position, i.e. a total amplitude of pivoting movement of the order of <NUM> degrees.

The aforementioned solution allowing pivotal movement of the outer casing <NUM> with respect to the retaining device <NUM> is of great advantage to improve comfort for the patient during transfer from a seated position to a standing position, and vice versa, as the outer casing <NUM> will follow the actual and natural movement of the patient's legs and knees during the assisted transfer. The proposed solution is fully integrated and is not made to detriment of the operation of the aforementioned manually-operable release mechanism. In other words, both functions can be implemented, without this leading to a complex arrangement.

Claim 1:
A patient lift apparatus (<NUM>) comprising a supporting frame (<NUM>), a boom portion (<NUM>) connected to the supporting frame (<NUM>) via a pivot joint (PJ1) to allow the boom portion (<NUM>) to pivot with respect to the supporting frame (<NUM>) about a pivot axis (PA1), a boom actuator (<NUM>) to mechanically assist pivotal movement of the boom portion (<NUM>) with respect to the supporting frame (<NUM>), and a leg/knee support (<NUM>) connected to the supporting frame (<NUM>),
characterized in that the leg/knee support (<NUM>) comprises:
- a retaining device (<NUM>) configured to cooperate with a support mount (<NUM>) provided on the supporting frame (<NUM>) to secure the leg/knee support (<NUM>) onto the supporting frame (<NUM>), the leg/knee support (<NUM>) being configured to be partly pivotable with respect to the support mount (<NUM>) about a pivot axis (PA3) and within a defined pivoting range;
- an outer casing (<NUM>) configured to be pivotable with respect to the retaining device (<NUM>) about said pivot axis (PA3) and within said defined pivoting range; and
- at least one spring element (<NUM>, <NUM>) coupling the outer casing (<NUM>) to the retaining device (<NUM>), which at least one spring element (<NUM>, <NUM>) is configured to bring the outer casing (<NUM>) to a default position with respect to the retaining device (<NUM>) when no external force is applied onto the outer casing (<NUM>).