Patent Application
20180280215
The present disclosure generally relates to a tilt assembly for a powered wheelchair. In particular, it relates to a tilt assembly which is configured to provide tilting of a seat assembly of a powered wheelchair, and to a powered wheelchair.
Powered wheelchairs are commonly fitted with a tilt/lift arrangement which allows adjustment of the orientation and/or the height of the wheelchair seat. Such adjustment may be anterior, i.e. forward, or posterior, i.e. backwards tilting, and/or lifting of the seat. Commonly, tilting is referred to as the operation that affects the orientation of the seat while lifting affects the height of the seat. A seat occupant or caretaker may thereby for example set the seat position according to desire or current need of the occupant. Some examples of reasons for adjusting the seat position include achieving pressure relief, resting in general, the ability to better reach things or otherwise accommodate to the environment. Moreover, adjustment of the seat height and orientation may be a desirable feature for control purposes to stabilise the wheelchair depending on speed and travel on inclined surfaces.
An example of a wheelchair with tilt and lift capabilities is disclosed in EP2823796 A1. The powered wheelchair comprises a chassis frame, a lift device having a base member which is fixedly arranged to the chassis frame, and a lifting member arranged to move rectilinearly relative to the base member along an axis defined by a longitudinal extension of the lifting member, a tilt frame, a first arm pivotally coupled to the lifting member and the tilt frame, and a second arm coupled to the base member, and which second arm is pivotally coupled to the first arm forming a pivot connection, wherein movement of the lifting member towards the extended position moves the pivot connection towards the base member and movement of the lifting member towards the retracted position moves the pivot connection away from the base member.
US6447064 B1 discloses a wheelchair with a tiltable seat. The wheelchair has a tilt fulcrum between 3 and 7 inches from the front edge of the seat pan and between 1 and 4 inches below the surface of the seat pan. This minimizes the elevation of the rider's knees when in a tilted position, and allows for more stability and a shorter wheel base. Manual self-tilting is facilitated by a gas strut arrangement disposed on brackets below the seat pan, and operated by a rider-controlled valve.
In the case of US6447064 B1, the elevation of the knees is minimised during tilting, because the gas strut is retracted to obtain a tilt position. The tilt frame is arranged horizontal when the gas strut is extended. This wheelchair is a manual wheelchair, which allows a design which lowers the back edge of the tilt frame to perform tilt. Powered wheelchairs on the other hand typically have batteries arranged below the seat limiting the amount of space available for tilt operations. This essentially renders implementation of the tilt functionality as disclosed in US6447064 B1 impossible.
The tilt and lift functionality of EP2823796 A1 provides an anterior/posterior tilt functionality for a powered wheelchair, but has a rather complex design.
In view of the above, a general object of the present disclosure is to provide a tilt assembly which solves or at least mitigates the problems of the prior art.
According to a first aspect of the present disclosure there is provided a tilt assembly for a powered wheelchair, comprising: an elongated base member provided with an axial channel, a lifting member configured to be received by the base member and to move rectilinearly in the channel, between a retracted position and an extended position relative to the base member, a tilt frame pivotally connected to the lifting member, the tilt frame being configured for mounting a seat assembly thereto, and an arm pivotally connected to the base member and to the tilt frame, wherein the tilt frame is configured to obtain a perpendicular orientation relative to a central axis of the lifting member when the lifting member is in the retracted position and to be inclined relative to the central axis when the lifting member is in the extended position, to thereby provide a tilt functionality.
An effect which may be obtainable thereby is a simple tilt function design which during tilt provides a negligible change of the point of gravity of a wheelchair occupant, resulting in good stability of a powered wheelchair during tilt.
According to one embodiment the base member is configured to be immovably mounted to a chassis frame of a powered wheelchair.
According to one embodiment the arm has a first end which is pivotally connected to the base member and a second end which is pivotally connected to the tilt frame.
According to one embodiment the tilt frame has an essentially planar surface configured for mounting a seat assembly of a powered wheelchair thereto.
According to one embodiment the pivot connection between the lifting member and the tilt frame is aligned with a central axis of the lifting member.
According to one embodiment the arm is configured to provide a controlled degree of tilt per height unit of movement of the lifting member. The arm hence controls the tilt motion of the tilt frame, due to its pivotal connection to both the base member and to the tilt frame.
According to one embodiment the arm comprises a linkage member. The arm may be formed of a single or a plurality of linkage members.
According to one embodiment the arm comprises an actuator. The arm may be an actuator configured to be set in a retracted actuator position and an extended actuator position to thereby control the distance between the pivot connection formed between the arm and the tilt frame and the pivot connection formed between the arm and the base member. As a result, more advanced tilting options may be provided, for example both posterior and anterior tilt, and even a lift functionality, using only a few components.
One embodiment comprises a resilient member configured to provide damping of the tilt frame. The damping effect will typically be larger when the lifting member is in the retracted position compared to when the lifting member is in the extended position. This is because in the former case the longitudinal axis of the arm and thus the resilient axis of the resilient member is at an acute angle with the tilt frame, while in the latter case, the same angle is closer to 90° degrees, which makes the lever arm for the force acting on the resilient member larger. When the force needed to compress the resilient member is larger a lesser degree of dampening will occur. Mainly, the dampening effect is desired when driving the wheelchair in normal position, i.e. with the tilt frame in a horizontal, non-tilted position. Thus, due to the design of the tilt assembly the shock absorption/damping capability of the resilient member is largest when in the non-tilted position.
According to one embodiment the resilient member is a spring.
The arm and the resilient member may according to one variation of the tilt assembly form a strut.
There is according to a second aspect of the present disclosure provided a powered wheelchair comprising: a chassis frame, and a tilt assembly according to the first aspect presented herein.
According to one embodiment the base member is immovably mounted to the chassis frame.
According to one embodiment the base member has a central axis which is oriented vertically when the powered wheelchair is arranged horizontally on a planar surface.
One embodiment comprises a seat assembly, wherein the seat assembly is mounted to the tilt frame.
Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to “a/an/the element, apparatus, component, means, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, etc., unless explicitly stated otherwise.
The specific embodiments of the inventive concept will now be described, by way of example, with reference to the accompanying drawings, in which:
The inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplifying embodiments are shown. The inventive concept may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. Like numbers refer to like elements throughout the description.
The base member 3 is configured to receive the lifting member 5. Hereto, the base member 3 is provided with an axial channel in which the lifting member 5 is configured to be received. The lifting member 5 is configured to move rectilinearly relative to the base member 3, in the axial channel, between a retracted position relative to the base member and an extended position relative to the base member 3. The lifting member 5 and the base member 3 are hence concentrically arranged. In the retracted position, a the lifting member 5 is received maximally by the base member 3, as shown in
The lifting member 5 may according to one variation be configured to be actuated between the retracted position and an extended position by means of a motor.
The base member 3 may according to one variation be configured to be immovably attached or mounted to a chassis frame of a powered wheelchair. The base member 3 is in this case, when mounted to the chassis frame, immovably arranged relative to the chassis frame.
The base member 3 is arranged to extend in a vertical plane when the tilt assembly 1 is mounted to a chassis frame and the powered wheelchair is placed on a horizontal support surface.
The tilt frame 7 is configured to allow a seat assembly to be mounted to the tilt frame 7. The tilt frame 7 is provided with an essentially planar surface, or a planar surface, 7a to which a seat assembly may be mounted. This essentially planar or planar surface 7a is typically an upper surface of the tilt frame 7. The upper surface is a surface which faces away from the base member 3 and the lifting member 5 and which is intersected by a central axis ii defined by the longitudinal extension of the lifting member 5.
The tilt frame 7 is pivotally connected to the lifting member 5. The tilt frame 7 is hence pivotable relative to the lifting member 5 about a pivot axis formed by the pivot connection A between the tilt frame 7 and the lifting member 5. The pivot connection A allows the tilt frame 7 to be moved relative to the base member 3 when the lifting member 5 is moved between the retracted and extended position.
The arm 9 extends between the base member 3 and the tilt frame 7. The arm 9 is pivotally connected to the tilt frame 7 and to the base member 3. The tilt frame 7 is hence pivotable relative to the arm 9 about a pivot axis formed by the pivot connection B between the arm 9 and the tilt frame 7. Moreover, the arm 9 is pivotable relative to the base member 5 about a pivot axis formed by the pivot connection C between the arm 9 and the base member 5. According to one variation, the pivot connection B forms one end of the arm 9 and the pivot connection C forms the other end of the arm 9.
The tilt frame 7 is according to the variation shown in
In the non-tilting position of the tilt assembly 1 shown in
Tilting is provided by movement of the lifting member 5 from its retracted position relative to the base member 3, as shown in
When the lifting member 5 is in the retracted position, the tilt frame 7 is arranged perpendicular to the central axis ii. In particular, the essentially planar surface 7a of the tilt frame 7 defines a plane which is arranged perpendicular to the central axis ii and the central axis 11 intersects this plane. When the lifting member 5 is in an extended position, the tilt frame 7 is inclined relative to the central axis ii. In particular, the essentially planar surface 7a is inclined relative to the central axis 11, so that there is an acute angle between the plane and the central axis 11.
The amount of tilt, or the tilt angle, of the tilt frame 7 of an assembled tilt assembly 1 is determined by the amount that the lifting member 5 is moved from the retracted position. The amount of tilt is hence determined by the position of the pivot connection A along the central axis 11. Maximal tilt is provided when the lifting member 5 reaches its maximally extended position relative to the base member 3. No tilt is obtained when the lifting member is maximally retracted into the base member 3.
The arm 9 provides a controlled tilting of the tilt frame 7. The arm 9 provides a controlled degree of tilt per height unit of movement of the lifting member 5. If no arm would be provided, the tilt frame would tilt uncontrollably to obtain a state of posterior tilt or anterior tilt depending on e.g. the centre of gravity and/or the weight of a seat occupant of a seat assembly mounted to the tilt frame. The maximal tilt that can be provided by the tilt assembly 1 is determined by the position of the pivot connection B along the tilt frame 7, the position of the pivot connection C along the base member 3, and on the length of the arm 9.
The arm 9 may for example comprise a single linkage member, as shown in
The powered wheelchair 15 comprises a plurality of wheels 17a-17c, in the present example two front caster wheels 17a, two drive wheels 17b and two rear caster wheels 17c. The powered wheelchair 15 furthermore comprises a chassis frame 19 on which at least one battery, not shown, is mounted for driving the drive wheels 17b, and the tilt assembly 1. The tilt assembly 1 or 1′ is mounted to the chassis frame 19. According to the present example, the tilt assembly 1 or 1′ is mounted to the chassis frame 19 in front of the at least one battery. The base member 3 is located centred between the two drive wheels 17b in a direction from one of the drive wheels 17b to the other drive wheel 17b.
The powered wheelchair 15 furthermore comprises a seat assembly 21, comprising a seat 21a and a backrest 21b. The seat assembly 21 is mounted to the tilt frame 7. In particular, the seat assembly 21 is fixedly mounted on top of the tilt frame 7, to the essentially planar surface 7a shown in
By moving the lifting member 5 from the retracted position towards an extended position, posterior tilting of the seat system 21 may be provided, as indicated by the arrow 23.
The inventive concept has mainly been described above with reference to a few examples. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the inventive concept, as defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 17164109.5 | Mar 2017 | EP | regional |
