Power middle wheel driving wheelchair with standing capability

Abstract

A powered middle wheel driven MWD wheelchair (1-1) comprises: a chassis (3); a seating system (15) attached to the chassis (3), the seating system (15) configured to be manipulated between a seating position and a standing position; a pair of drive wheels (13); a pair of front swing arms (5) pivotally connected to the chassis (3); and a front support wheel (9) attached to a respective one of the pair of front swing arms (5) wherein each front swing arm (5) is configured to pivot relative to the chassis (3) between a first position in which the front support wheel (9) is in its uppermost position relative to the chassis (3) and a second position in which the front support wheel (9) is in its lowermost position relative to the chassis (3), and wherein the pair of front swing arms (5) is configured to pivot to a first position when the seating system (15) is in the standing position, thereby tilting the chassis (3) forward with respect to the ground or floor surface (18).

Description

Technical Field

[0001] The present disclosure generally relates to mid-wheel drive wheelchairs. Background Art

[0002] A mid-wheel drive (MWD) wheelchair has front wheels, rear wheels, and drive wheels disposed between the front wheels and the rear wheels.

[0003] Some MWD wheelchairs have stand-up capability. This means that the seating system, including the seat and backrest, can be manipulated between a default lowered or seated position and an upright position. In the upright position, the seat is tilted forward and the backrest is held in a generally upright position, supporting the user in a standing position.

[0004] When the seat system has been placed in the upright position, the MWD wheelchair must be stable to ensure that it does not tip forward.

[0005] EP2114335 discloses a standing wheelchair having a central drive wheel and front wheels operatively connected by an endless chain. The frame has a front part and a rear part connected to each other in an articulated manner. In the seated position, the front wheel is not in direct contact with the ground. In the standing position, the front wheel is in contact with the ground, but the central wheel is not. A disadvantage of this wheelchair is that it has a wide turning radius, making it impractical for indoor use. In addition, the drive arrangement is complex and expensive, and leaving the front wheel off the ground in the seated position has a negative impact on the driving comfort of the user.

[0006] WO2020188345 discloses a powered wheelchair support having a drive wheel and front and rear support wheels. The wheelchair is configured to move between a seated position and a standing position. In order to prevent the wheelchair from tipping over due to the forward and / or upward movement of the center of gravity in the standing position, a suspension assembly is provided, which allows the suspension system to articulate when the user positioning system is in the seated position, and limits or completely locks this articulated movement when the user positioning system is in the standing position. However, this is achieved by a system of connecting rods and locking / limiting elements that inevitably increase the complexity and drive cost.

[0007] JP2018099233 A discloses a wheelchair comprising a pair of base frames to which front caster arms are immovably fixed. The wheelchair also has a movable frame connected to a corresponding one of the base frames for changing the position of the user. Summary of the invention

[0008] A general object of the present disclosure is to provide a MWD wheelchair which solves or at least alleviates the problems of the prior art.

[0009] Therefore, a powered mid-wheel drive wheelchair, i.e., an MWD wheelchair, is provided, comprising: a chassis; a seat system, the seat system being attached to the chassis, the seat system being configured to be maneuvered between a seated position and a standing position; a pair of drive wheels; a pair of front swing arms, the pair of front swing arms being pivotally connected to the chassis; and front support wheels, the front support wheels being attached to a corresponding one of the pair of front swing arms, wherein each front swing arm is configured to pivot relative to the chassis between a first position and a second position, wherein in the first position, the front support wheel is in its uppermost position relative to the chassis, and in the second position, the front support wheel is in its lowermost position relative to the chassis, and wherein the pair of front swing arms are configured to pivot to the first position when the seat system is in the standing position, thereby tilting the chassis forward relative to a ground or floor surface.

[0010] Thus, the seat system can be set in a standing position while maintaining an adequate level of stability because the pair of front swing arms bottom out / reach their lowest point in the first position and the chassis tilts forward. The drive wheels remain in contact with the ground or floor surface, thereby supporting the weight of the MWD wheelchair and occupant.

[0011] Furthermore, sufficient stability can be obtained without having to resort to complex locking mechanisms to prevent tipping behaviour, which is prone to quality problems and limits the suspension movement at extreme seat positions. No additional sensors, actuators or warning systems are required, making the solution more robust and cost-effective than those found in the prior art. The solution can thus be made completely passive.

[0012] According to an example, when the seating system is in the standing position, the inclination angle of the chassis relative to a horizontal ground or floor surface may be at most 6°, such as in the range of 2° to 4°.

[0013] Due to the center of gravity shift caused by the seat system reaching the standing position, the pair of front swing arms can be pivoted to the first position and the chassis can be tilted forward. Therefore, the pivoting of the front swing arms to the first position (in the first position, the front swing arms reach the lowest point) and the tilting of the chassis are passive because they occur in response to the movement of the seat system from the sitting position to the standing position.

[0014] According to one embodiment, in the standing position of the seating system, the common center of gravity of the powered MWD wheelchair and its occupant is located between a first vertical plane and an axle plane, wherein the first vertical plane extends through the pivotal connection of the pair of front swing arms to the chassis, and the axle plane is a second vertical plane in which the axles of the front support wheels are accommodated when the powered MWD wheelchair is resting on a flat horizontal surface.

[0015] The term "occupant" refers to a user to whom the MWD wheelchair has been fitted with respect to that user's weight and body type.

[0016] Each front swing arm may be rigid.

[0017] According to one embodiment, for each front swinging arm, there is a horizontal distance L between the pivot connection of the front swinging arm and the chassis and the axle plane, wherein, when the seating system is in the standing position, the common center of gravity is contained in a third vertical plane, which is located between 20% and 75%, such as between 30% and 60%, of the horizontal distance L measured from the pivot connection.

[0018] One embodiment includes a pair of rear swinging arms pivotally connected to the chassis, wherein each front swinging arm is connected to a corresponding rear swinging arm to enable force transfer between the pair of front swinging arms and the pair of rear swinging arms.

[0019] Each rear swing arm may be rigid.

[0020] One embodiment includes a linkage member wherein each front swing arm and the connected rear swing arm are connected via a respective linkage member.

[0021] According to one embodiment, each link member is rigid or substantially rigid.

[0022] The link member may alternatively be provided with some resilience, ie have limited / little flexibility, or be semi-rigid.

[0023] One embodiment includes a first resilient member connected to the chassis and a corresponding rear swing arm.

[0024] The first elastic member may be, for example, a spring, such as a coil spring, an air spring, a leaf spring, or the first elastic member may be made of a material having elastic properties, such as rubber.

[0025] In one example, the wheelchair includes a shock absorbing device including the first elastic member and a damping unit.

[0026] One embodiment includes a pair of suspension arms, each suspension arm connecting a respective front swing arm and a rear swing arm, wherein each first elastic member is directly connected to the respective suspension arm and the chassis.

[0027] One embodiment includes second elastic members, each second elastic member is directly connected between a corresponding pair of rear swing arms and the suspension arm.

[0028] The second elastic member may be, for example, a spring, such as a coil spring.

[0029] According to one embodiment, each second elastic member is configured to force the pair of rear swing arms and the suspension arms directly connected thereto to separate.

[0030] When the chassis is tilted forward in the standing position of the seat system, the pair of rear swing arms thereby come into contact with the ground. Although this may not contribute to any additional stability, it can convey a visual perception of greater stability to the user.

[0031] According to one embodiment, each suspension arm and the connected rear swing arm share a pivot connection with the chassis.

[0032] One embodiment comprises a seat support to which the seat system is mounted, wherein, in the standing position, when the powered MWD wheelchair rests on a horizontal surface, the seat support is at an angle α of at least 50°, e.g. at least 60° or at least 70° relative to the horizontal plane, or wherein the seat support causes the seat of the seat system to be at an angle α of at least 50°, e.g. at least 60° or at least 70° relative to the horizontal plane when the powered MWD wheelchair rests on a horizontal surface.

[0033] One embodiment includes a battery, wherein the chassis houses the battery.

[0034] The chassis may be a chassis box.

[0035] According to one embodiment, in the first position, the pair of front swing arms bottom out / reach a lowest point.

[0036] According to one embodiment, in the standing position of the seating system, the pair of front swing arms pivot to the first position, causing the chassis to tilt forward.

[0037] According to one embodiment, the pivoting of the pair of front swing arms to the first position and the forward tilting of the chassis are achieved completely passively (ie without any motor or actuator).

[0038] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless otherwise explicitly defined herein. Unless otherwise explicitly stated, all references to "an / the element, device, component, means", etc. should be openly interpreted as referring to at least one instance of an element, device, component, means, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Specific embodiments of the present inventive concept will now be described by way of example with reference to the accompanying drawings, in which:

[0040] Figure 1schematically shows a side view of a general example of a MWD wheelchair;

[0041] Figure 2 Schematically shows Figure 1 A side view of an example implementation of an MWD wheelchair in FIG. 1 with the seat system in a seated position;

[0042] Figure 3 Schematically shows Figure 2 A side view of the MWD wheelchair in which the seat system is in a standing position;

[0043] Figure 4 Schematically shows Figure 1 A side view of an example implementation of an MWD wheelchair in FIG. 1 with the seat system in a seated position;

[0044] Figure 5 Schematically shows Figure 4 A side view of the MWD wheelchair in FIG. 1 with the seat system in a standing position; and

[0045] Figures 6 to 9 Shows Figure 1 Various alternative examples of implementations of the MWD wheelchair in FIG. DETAILED DESCRIPTION

[0046] The inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments are shown. However, the inventive concept may 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 comprehensive and complete and will fully convey the scope of the inventive concept to those skilled in the art. Throughout the specification, the same reference numerals refer to the same elements.

[0047] Figure 1 An example of an MWD wheelchair 1 is schematically shown.

[0048] The MWD wheelchair 1 comprises a chassis 3. The chassis 3 may be an open or closed chassis box.

[0049] The MWD wheelchair 1 includes a pair of front swing arms 5. Figure 1 Only one front swing arm 5 is shown in the side view.

[0050] The front swing arm 5 is pivotally connected to the chassis 3 .

[0051] The MWD wheelchair 1 comprises front support wheels 9. Each front support wheel 9 is connected to a corresponding front swing arm 5.

[0052] The front support wheels 9 can be casters, such as Figure 1 The front support wheels may alternatively be, for example, multi-directional wheels or omnidirectional wheels.

[0053] The MWD wheelchair 1 includes a pair of rear swing arms 7. Figure 1 Only one rear swing arm 7 is shown in the side view.

[0054] The MWD wheelchair 1 comprises rear support wheels 11. Each rear support wheel 11 is connected to a corresponding rear swing arm 7.

[0055] The rear support wheel 11 can be a caster, such as Figure 1 The rear support wheels may alternatively be, for example, multi-directional wheels or omni-directional wheels.

[0056] The MWD wheelchair 1 includes a pair of driving wheels 13. The driving wheels 13 are arranged between the front supporting wheels 9 and the rear supporting wheels 11.

[0057] The drive wheel 13 is pivotably connected to the chassis 3 .

[0058] The MWD wheelchair 1 includes a battery (not shown) arranged inside the chassis 3 .

[0059] The MWD wheelchair 1 includes a drive motor (not shown) configured to drive a corresponding one of the drive wheels 13 .

[0060] The drive motor is configured to be powered by a battery.

[0061] The MWD wheelchair 1 comprises a seat system 15 . The seat system 15 is attached to the chassis 3 .

[0062] The seat system 15 includes a seat 15a and a backrest 15b.

[0063] The seat system 15 is configured to Figure 1 Maneuverable between a seated position and a standing position as shown.

[0064] The MWD wheelchair 1 may include a steering system configured to vertically lift the seat 15a and / or tilt the seat 15a forward. An example of a suitable steering system is the lift / tilt device disclosed in WO2015 / 004177. Such a system may be operated by a motor and may provide one of forward tilt, rearward tilt, full standing tilt and lift, or a combination of forward / rearward tilt, full standing tilt and lift, depending on the particular implementation.

[0065] The steering system may also be configured to control movement of the backrest 15b. The steering ring system is configured to steer the seating system 15 between a sitting position and a standing position by providing tilt and lift.

[0066] The MWD wheelchair 1 includes a seat system support 17 to which the seat system 15 is mounted. The seat system support 17 includes a seat support 17a and a backrest support 17b pivotally connected to the seat support 17a. The seat support 17a may be a seat frame. The backrest support 17b may be a backrest frame. The seat 15a may be attached to the seat support 17. The backrest 15b may be attached to the backrest support 17b.

[0067] The seat support 17a is configured to move together with the seat 15a when the seat 15a is tilted or lifted.

[0068] Each front swing arm 5 is configured to pivot between a first position and a second position relative to the chassis 3. In the first position, the front support wheel 9 is in its uppermost position relative to the chassis 3. Figure 1 In the first position, the front swing arm 5 is bottomed out. The first position is thus one of two extreme positions that the front swing arm 5 can reach relative to the chassis 3. The pivoting towards the first position can occur, for example, when the front support wheel encounters a raised obstacle or when the seat system 15 is arranged in a standing position, as will be explained in more detail.

[0069] In the second position, the front support wheel 9 is in its lowest position relative to the chassis 3. Figure 1 In the embodiment, this means that the front swing arm 5 pivots clockwise. The pivoting towards the second position can occur, for example, when the ground level below the front support wheel 9 is lower than the ground level below the drive wheel 13, such as when crossing a curb or driving on a pothole.

[0070] In the remaining figures, the front and rear swing arms are schematically shown to illustrate the operational connection between the attachment points in the chassis and the front and rear support wheels, respectively. Although the castors are not so depicted, Figures 2 to 9 The illustrated embodiment of contemplates the casters being used as the front support wheels and the rear support wheels, respectively.

[0071] Figure 2 Schematically shows Figure 1 An example implementation of the MWD wheelchair 1 in FIG. Figure 2 The exemplary MWD wheelchair 1 - 1 in FIG. 1 has a seat system 15 in a seated position.

[0072] exist Figure 2 In the embodiment, the ground or floor surface 18 on which the MWD wheelchair 1-1 rests is a flat horizontal surface. All wheels, i.e. the rear support wheels 11, the drive wheels 13 and the front wheels 9 are in contact with the ground or floor surface 18.

[0073] According to this example, the drive wheels 13 are mounted to the respective front swing arms 5 .

[0074] Each front swinging arm 5 has its pivot connection 5 a to the chassis 3 at a respective lateral side of the chassis 3 .

[0075] Each rear swing arm 7 has its pivot connection 7 a to the chassis 3 at a respective lateral side of the chassis 3 .

[0076] The MWD wheelchair 1-1 includes two link members 19. Each link member 19 connects one front swing arm 5 with the corresponding rear swing arm 7. Each front swing arm 5 is thereby connected to the corresponding rear swing arm 7 to achieve force transmission between the front swing arm 5 and the rear swing arm 7. Therefore, the pivotal movement of the front swing arm 5 can cause a pivotal movement response of the rear swing arm 7 to which it is connected.

[0077] According to this example, the link members 19 are rigid. Specifically, each link member 19 is rigid along its longitudinal axis between the connection points of the link member 19 and the front swing arm 5 and the rear swing arm 7 .

[0078] The MWD wheelchair 1-1 comprises a first elastic member 21 connected to the chassis 3 and the rear swing arm 7. The first elastic member 21 may form a part of a shock absorbing device of the MWD wheelchair 1-1.

[0079] Figure 3 The MWD wheelchair 1 - 1 is shown when the seating system 15 is in a standing position. The drive wheels 13 are in contact with the ground or floor surface 18 when the seating system 15 is in a standing position.

[0080] In the standing position of the seating system 15, the seat support 17a is at an angle α of at least 50° (such as at least 60° or at least 70°) relative to the horizontal ground or floor surface 18 or the seat 15a is at an angle α of at least 50° (such as at least 60° or at least 70°) relative to the horizontal ground or floor surface 18.

[0081] In the standing position of the seat system 15, the front swing arm 5 has pivoted to the first position. This causes the chassis 3 to tilt forward. As a result, the lower front edge 3a of the chassis 3 moves closer to the horizontal ground or floor surface 18, and the lower rear edge 3b of the chassis 3 moves further away from the horizontal ground or floor surface 18. It should be understood that the pivoting of the front swing arm 5 to the first position (or bottoming out) and the tilting of the chassis 3 are passive. Similarly, the forward tilting of the chassis 3 is passive. This passive movement is in response to the seat system 15 moving from the sitting position ( Figure 2 ) to standing position( Figure 3 ) movement.

[0082] Angle α=β+θ, where β is the angle between the seat support 17a and the top of the chassis 3 and θ is the inclination angle of the chassis 3 relative to the horizontal ground or floor surface 18. The inclination angle θ of the chassis 3 is typically at most 6°, for example 2°-4°.

[0083] The common center of gravity G of the MWD wheelchair 1-1 and its occupant is located between a first vertical plane P1 extending through the pivot connection 5a of the front swing arm 5 and the axle plane P2, which is a second vertical plane containing the axles of the front support wheels 9 when the MWD wheelchair 1-1 is resting on a horizontal ground or floor surface 18.

[0084] It should be noted here that when the front support wheel 9 is a castor, the wheel axle moves between the front and rear driving directions. Therefore, for the castor, when the castor is in its most rearward position, the wheel axle plane P2 is defined. This is the position taken by the castor when the MWD wheelchair 1-1 is driven in a straight direction.

[0085] For each front swing arm 5, there is a horizontal distance L between the pivot connection 5a of the front swing arm and the chassis 3 and the axle plane P2. According to one example, when the seat system 15 is in a standing position and the MWD wheelchair 1-1 is resting on a horizontal ground or floor surface 18, the common center of gravity G is contained in a third vertical plane P3, which is located between 20% and 75%, such as 30% and 60%, of the horizontal distance L measured from the pivot connection 5a.

[0086] Figure 4 Schematically shows Figure 1 Another example implementation of the MWD wheelchair 1 in FIG. Figure 4 The exemplary MWD wheelchair 1-2 in FIG. 1 has a seat system 15 in a seated position. The MWD wheelchair 1-2 is generally similar to the MWD wheelchair 1-1. The differences will be explained below.

[0087] Compared with the MWD wheelchair 1 - 1 , the MWD wheelchair 1 - 2 further includes a pair of suspension arms 23 .

[0088] The suspension arm 23 is pivotally connected to the chassis 3 .

[0089] Each suspension arm 23 is connected to the corresponding front swing arm 5 and rear swing arm 7-2.

[0090] Each rear swing arm 7 - 2 shares a pivot connection to the chassis 3 with a respective suspension arm 23 .

[0091] According to this example, each link member 19 is directly connected between the front swing arm 5 and the suspension arm 23 .

[0092] Each first elastic member 21 is directly connected to the corresponding suspension arm 23 and the chassis 3 .

[0093] The MWD wheelchair 1-2 includes second elastic members 25. Each second elastic member 25 is directly connected between a corresponding pair of rear swing arms 7 and the suspension arm 23.

[0094] Each second elastic member 25 is configured to force a pair of rear swing arms 7-2 and a suspension arm 23 directly connected thereto to separate. A pair of rear swing arms 7-2 and the suspension arm 23 have the same pivot connection with the chassis 3, which means that the second elastic member 25 attempts to rotate the rear swing arms 7-2 and the suspension arm 23 away from each other.

[0095] Figure 5 The MWD wheelchair 1-2 is shown when the seat system 15 is in a standing position. The front swing arm 5 has been pivoted to the first position. This causes the chassis 3 to tilt forward, similar to Figure 3 MWD wheelchair shown in 1-1.

[0096] Due to the second elastic member 25, the rear swing arm 7 pivots toward the ground or floor surface 18 so that the rear support wheel 11 contacts the ground or floor surface 18. Therefore, when the seat system 15 is in the standing position, the rear support wheel 11 rests on the ground or floor surface 18.

[0097] Figures 6 to 9 Various other examples of implementations of the MWD wheelchair 1 are shown, all of which show the chassis and front and rear swing arms when the seat system is in a standing position and the chassis is tilted forward.

[0098] exist Figure 6 In the example of the MWD wheelchair 1-3, the rear swing arm 7-3 is not connected to the corresponding front swing arm 5 via a connecting rod member. In addition, according to this example, each first elastic member 21 is directly connected between the chassis 3 and the corresponding front swing arm 5. This is also Figure 7 The situation of MWD wheelchairs 1-4.

[0099] exist Figure 8 In the example of the MWD wheelchair 1-5 in FIG. 1 , the first elastic member 21 is directly connected between the chassis 3 and the front swing arm 5. In addition, there is an additional elastic member 21-5 directly connected to the corresponding rear swing arm 7-5 and the chassis 3.

[0100] Fig. 9 An example of an MWD wheelchair 1-6 is shown, in which the front swing arm 5 is connected to the chassis but not to the drive wheel. The MWD wheelchair 1-6 comprises an additional front swing arm 5-6, which is pivotally connected to the chassis 3 at a different connection point than the front swing arm 5 and is parallel to the corresponding front swing arm 5. Each additional front swing arm 5-6 is pivotally connected to a mounting device in a housing connected to the front support wheel 9. In addition, an additional elastic member 21-6 is connected to the corresponding rear swing arm 7-6 and the chassis 3.

[0101] 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.

Claims

1. A powered mid-wheel drive wheelchair, i.e., an MWD wheelchair (1; 1-1; 1-2; 1-3; 1-4； 1-5； 1-6), the powered mid-wheel drive wheelchair comprises: Chassis (3); a seat system (15) attached to the chassis (3), the seat system (15) being configured to be maneuvered between a seated position and a standing position; a pair of driving wheels (13); a pair of front swing arms (5; 5-6) pivotally connected to the chassis (3); and a front support wheel (9) attached to a corresponding one of the pair of front swing arms (5; 5-6), wherein each front swing arm (5; 5-6) is configured to pivot relative to the chassis (3) between a first position and a second position, wherein in the first position the front support wheel (9) is in its uppermost position relative to the chassis (3), and in the second position the front support wheel (9) is in its lowermost position relative to the chassis (3), and Wherein, the pair of front swing arms (5; 5-6) are configured to pivot to the first position when the seat system (15) is in the standing position, thereby tilting the chassis (3) forward relative to the ground or floor surface (18).

2. The powered MWD wheelchair (1; 1-1; 1-2; 1-3; 1-4; 1-5; 1-6) according to claim 1, wherein: In the standing position of the seating system (15), the common center of gravity (G) of the powered MWD wheelchair (1; 1-1; 1-2; 1-3; 1-4; 1-5; 1-6) and its occupant is located between a first vertical plane (P1) extending through the pivot connection (5a) of the pair of front swing arms (5; 5-6) and the chassis (3), and an axle plane (P) which is a second vertical plane in which the axle of the front support wheel (9) is accommodated when the powered MWD wheelchair (1; 1-1; 1-2; 1-3; 1-4; 1-5; 1-6) is placed on a flat horizontal surface.

3. The powered MWD wheelchair (1; 1-1; 1-2; 1-3; 1-4; 1-5; 1-6) according to claim 2, wherein: For each front swing arm (5; 5-6), there is a horizontal distance L between the pivot connection (5a) between the front swing arm (5; 5-6) and the chassis (3) and the axle plane (P), wherein, when the seat system (15) is in the standing position, the common center of gravity (G) is contained in a third vertical plane (P3), and the third vertical plane (P3) is located between 20% and 75%, such as between 30% and 60%, of the horizontal distance L measured from the pivot connection (5).

4. A powered MWD wheelchair (1; 1-1; 1-2) according to any one of the preceding claims, comprising a pair of rear swing arms (7) pivotally connected to the chassis (3), wherein: Each front swing arm (5) is connected to a corresponding rear swing arm (7) to achieve force transmission between the pair of front swing arms (5) and the pair of rear swing arms (7).

5. The powered MWD wheelchair (1; 1-1; 1-2) according to claim 4, comprising a connecting rod member (19), wherein: Each front swing arm (5) and the connected rear swing arm (7) are connected via a corresponding connecting rod member (19).

6. The powered MWD wheelchair (1; 1-1; 1-2) according to claim 5, wherein: Each link member (19) is rigid.

7. A powered MWD wheelchair (1; 1-1; 1-2) according to any one of claims 4 to 6, comprising a first elastic member (21) connected to the chassis (3) and a corresponding rear swing arm (7).

8. The powered MWD wheelchair (1; 1-2) according to claim 7, comprising a pair of suspension arms (23), each suspension arm (23) being connected to a corresponding front swing arm (5) and a rear swing arm (7), wherein: Each first elastic member (21) is directly connected to a corresponding suspension arm (23) and the chassis (3).

9. The powered MWD wheelchair (1; 1-2) according to claim 8, comprising second elastic members (25), each of which is directly connected between a corresponding pair of rear swing arms (7) and the suspension arm (23).

10. The powered MWD wheelchair (1; 1-2) according to claim 9, wherein: Each second elastic member (25) is configured to force the pair of rear swing arms (7) and the suspension arms (23) directly connected thereto to separate.

11. The powered MWD wheelchair (1; 1-2) according to claim 10, wherein: Each suspension arm (23) and the connected rear swing arm (7) share a pivot connection with the chassis.

12. A powered MWD wheelchair (1; 1-1; 1-2; 1-3; 1-4; 1-5; 1-6) according to any one of the preceding claims, comprising a seat support (17a), the seat system (15) being mounted to the seat support (17a), wherein In the standing position, when the powered MWD wheelchair rests on a horizontal surface, the seat support (17a) forms an angle α of at least 50°, such as at least 60° or at least 70° relative to the horizontal plane, or when the powered MWD wheelchair rests on a horizontal surface, the seat support (17a) causes the seat (15a) of the seat system (15) to form an angle α of at least 50°, such as at least 60° or at least 70° relative to the horizontal plane.

13. A powered MWD wheelchair (1; 1-1; 1-2; 1-3; 1-4; 1-5; 1-6) according to any one of the preceding claims, comprising a battery, wherein: The chassis (3) accommodates the battery.

14. A powered MWD wheelchair (1; 1-1; 1-2; 1-3; 1-4; 1-5; 1-6) according to any one of the preceding claims, wherein In the first position, the pair of front swing arms (5) reach the lowest point.

15. The powered MWD wheelchair (1; 1-1; 1-2; 1-3; 1-4; 1-5; 1-6) according to any one of the preceding claims, wherein In the standing position of the seat system (15), the pair of front swing arms (5) are pivoted to the first position, thereby causing the chassis (3) to tilt forward.

16. A powered MWD wheelchair (1; 1-1; 1-2; 1-3; 1-4; 1-5; 1-6) according to any one of the preceding claims, wherein The pivoting of the pair of front swing arms (5) to the first position and the forward tilting of the chassis (3) are both achieved passively.

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