Method of manufacturing a seat unit for a wheelchair, and a seat unit

Abstract

Herein is disclosed a method of manufacturing a seat unit for a wheelchair, and a seat unit for a wheelchair The method comprises the steps of determining a user's needs for support and pressure relief, and thereafter selecting a basic seat cushion module (1) and a basic backrest module (2) before 3D-printing a seat unit adaptation module (4; 5) using information about the determined support and pressure relief needs of the user, for adapting the basic seat cushion module (1) and / or the basic backrest module (2) to the user. The adaptation module (4; 5) is printed with an open 3D structure (3).

Description

[0001] METHOD OF MANUFACTURING A SEAT UNIT FOR A WHEELCHAIR, AND A SEAT UNIT

[0002] The invention concerns a method of manufacturing a seat unit for a wheelchair, wherein the seat unit is adapted for a user of the wheelchair. The invention further concerns a seat unit manufactured using said method. The seat unit comprises a seat cushion and a backrest, and the method comprises at least the steps of determining a user’s needs for support and pressure relief, for adapting the seat unit to the user.

[0003] Wheelchair users often experience discomfort and pressure sores as a result of prolonged sitting. A seat unit for a wheelchair typically include a seat cushion and a backrest. There are different types of wheelchair seat cushions and backrests available, and a lot has been done to better adapt seat units to the wheelchair user, for increased comfort. Conventional wheelchair seat cushions and backrests have a rigid support portion, typically made of metal or hard plastics, and a soft portion made of foam, fluid, or aircontaining shapes.

[0004] Prior art solutions for better adapted wheelchair seat units, are generally found in four categories:

[0005] 1) Contoured seat cushions and / or backrests made for example of foam.

[0006] 2) Seat cushions and / or backrests comprising multiple standard parts, typically made of foam, which can be moved relatively to each other, to achieve a seat unit adapted for the user.

[0007] 3) Special made seat cushions and / or backrests moulded to fit the user, based on measures and / or computer scanning of the user.

[0008] 4) 3D-printed seat cushions and / or backrests typically made of thermoplastic polyurethane (TPU), and where the 3D-print is based on computer scanning of the user.

[0009] The two first categories are often combined in prior art seat units. One example is shown in patent publication EP1905404A2 which discloses a seat cushion having a contoured base member and other, smaller, insert members of different density than the base member, received in recesses in the base member. Another example is shown in patent publication EP2575721A1, wherein multiple shaped blocks are used for putting together a seat unit which provides the necessary support for a user of the seat unit.

[0010] These seat units have some clear advantages, especially that the same seat unit can be adapted to better fit multiple users. However, when it comes to properly supporting a user in their main wheelchair, more personally adapted seat cushions and / or backrests, like those in categories 3 and 4 above, are preferred.

[0011] Examples of custom moulded seat units for wheelchairs, are the PinDot Silhouette Cushions and the PinDot Contourll Systems made by Invacare Corporation. Such seat units are typically made of foams of different densities for providing both support and pressure relief, as best suited for the actual user of the seat unit.

[0012] Disadvantages of custom moulded seat units include that they are costly and often quite heavy. In addition, if the user’s needs change over time, there are very limited possibilities for adjusting a custom moulded seat.

[0013] 3D-printed seat units for wheelchairs have emerged as a potential solution to the disadvantages mentioned above. 3D-print technology offers a possibility to make seat units, including seat cushions and backrests, which allow for customized contouring and support. Such seat units are, as mentioned above, typically made of TPU. 3D-printing allows for cushions to be made in one piece, while at the same time having areas of different density. Some solutions also show a smooth transition between such areas of different density. One manufacturer of 3D-printed seat units is the Danish company CREATE IT REAL A / S.

[0014] Some disadvantages of 3D-printed seat units are that they are expensive and slow to produce. It could take as much as one day to create a single cushion or back rest. With a considerable production time like that, such seat units are not yet possible to produce on a large scale without them being very expensive.

[0015] The object of the invention is to provide a seat unit for a wheelchair, wherein at least one of the seat cushion and the backrest of a seat unit, is adapted to the user’s needs for support and pressure relief, and wherein the seat unit is affordable, quick to produce, and easy to adapt to changing needs of the user.

[0016] In a first aspect, the invention concerns a method of manufacturing a seat unit for a wheelchair, the seat unit comprising a seat cushion and a backrest, the method comprising the steps of:

[0017] - determining a user’s needs for support and pressure relief;

[0018] - selecting a basic seat cushion module, the basic seat cushion module having a top surface facing the user in a position of use;

[0019] - selecting a basic backrest module, the basic backrest module having a front surface facing the user in a position of use;

[0020] - 3D-printing a seat unit adaptation module using information about the determined support and pressure relief needs of the user; and

[0021] - arranging the adaptation module in connection with at least a portion of the top surface of the basic seat cushion module and / or a portion of the front surface of the basic backrest module; wherein the adaptation module is printed with an open 3D structure.

[0022] Compared to prior art solutions, the method of manufacturing a seat unit according to the present invention, is more affordable, quicker, and the resulting seat units are easy to adapt to a user’s changing needs. Seat units made according to this method, have proven to perform better in pressure tests carried out by the Applicant, than prior art seat units. This effect was surprising, as it has been a common assumption in this field, that 3D- printed, custom-made seat units perform best.

[0023] The term “determining a user’s needs for support and pressure relief” covers different options: in one embodiment “determining” means that the manufacturer of the seat unit takes into account for example a known diagnosis or health issue which requires certain adjustments of a seat unit for being comfortable for a user having said diagnosis or health issue. This step of the method may include referring to experience. In another embodiment, “determining” means that the user themselves or a therapist assisting the user, states the user’s needs, thus requesting certain properties of the seating unit.

[0024] By basic seat cushion module and / or basic backrest module is herein meant modules that as such are not individually made for the user of the wheelchair, but which are chosen as a starting point for creating a seat unit adapted for the user. These basic modules may come in different shapes and materials and may be chosen based on the determined needs of the user.

[0025] 3D-print technology makes it possible to create custom-made products since each seat cushion and / or back rest is created by a specific computer program, and the parameters can be changed. When combining 3D-printing of an adaptation module for a seat unit with basic seat cushion modules and basic backrest modules of more commonly available kinds, the production time and production costs are reduced.

[0026] One of the main advantages of 3D-printing is seen as the possibility to produce seat cushions and backrests, and also entire seat units, in one piece, in a light material, and personally adapted to the end user. It is therefore counter-intuitive, and may even look like a compromise, to step away from this approach and use 3D-printing only for the adaptation module.

[0027] There is a seat cushion standard which suggests testing wheelchair seat cushions. As mentioned above, tests carried out by the Applicant show that classic seat unit materials like foam of different types and densities, perform well when tested against new materials as the TPU-material found in 3D-printed cushions. What was surprising, was the finding that foam-based cushions in combination with 3D-printed portions of TPU perform even better.

[0028] In addition to improving the manufacturing process, the method according to the invention, therefore also results in seat units for wheelchairs, where the seat units perform unexpectedly better in pressure tests than any of the prior art solutions.

[0029] Another problem solved by the invention, is that it makes it possible to easily and in an affordable way, further adapt or change the seat unit at a later stage. In the event that the user for example develops further needs or the seat unit is to be adapted to a new user, the seat unit may be completely changed only by 3D-printing a new adaptation module.

[0030] Another option for solving the problem of adapting the seat unit for the user who develops further needs, is to exchange the basic seat cushion module and / or the basic backrest module for another basic seat cushion module and / or basic backrest module of different material and / or different shape. Even another option is that one or more standard modules may be added to one or both of the seat cushion and the backrest. This shows that there are multiple quick ways of adapting the seat unit without having to create a new one.

[0031] The open 3D structure may be a gyroid structure. Gyroid structure is known as being ideal for parts requiring durability and resilience, as this structure has excellent load-bearing capabilities.

[0032] The adaptation module may comprise at least two zones of different density. The method may further comprise the step of obtaining specific information about the user’s needs and measures. While a seat unit is very well adapted for a user based on the determined information about health condition and the user’s own input, a further step for personalising the seat unit may be to also take into consideration specific combinations of health conditions and / or specific details about the user’s body. As an example, a person may have asymmetrical needs or degenerative conditions that calls for more specific adaptation of the seat unit as a whole and of the adaptation module in particular.

[0033] Obtaining specific information about the user’s needs and / or measures, may include at least one of:

[0034] - manually measuring the user;

[0035] - preparing a mould of the user; and

[0036] - scanning the user by means of a 3D-scanner.

[0037] The step of determining the user’s needs may include specifying in which areas of the body the user needs pressure and pressure relief.

[0038] In an embodiment wherein the adaptation module comprises at least two zones of different density, these zones may be adapted to specified areas where the user needs pressure and pressure relief. This means that the information about the user’s specific needs for pressure and pressure relief may be “translated” into defining pressure zones and relief zones of the seat unit, and in some embodiments particularly in the adaptation module.

[0039] At least one of the basic backrest module and the basic seat cushion module may be contoured. Contouring may be in the form of side supports in the seat cushion module providing support for the thighs. There may also be a mid-support, for supporting between the thighs. Contouring may include one or more of both supports and relief recesses. The skilled person is familiar with the concept of contoured cushions, and this will not be elaborated further herein.

[0040] The basic seat cushion module and / or the basic backrest module may be made of foam. Different types of foam are known to be used in seat units for wheelchairs. Some examples are open cell foam such as polyurethane foam, closed cell foam such as polyethylene foam, or viscoelastic foam, i.e. memory foam, typically made of polyurethane and additives. The basic seat cushion module and / or the basic backrest module may comprise different materials in combination and / or different elements put together to form the basic seat cushion module and / or the basic backrest module. One example may be a basic seat cushion module comprising foam in combination with one or more pockets of a fluid either in the form of a gas (air) or a liquid.

[0041] In a second aspect, the invention concerns a seat unit for a wheelchair, the seat unit comprising:

[0042] - a basic seat cushion module having a top surface for facing a user in a position of use;

[0043] - a basic backrest module having a front surface facing a user in a position of use; and

[0044] - a seat unit adaptation module arranged in connection with at least a portion of the top surface of the basic seat cushion module and / or the front surface of the basic backrest module; wherein the adaptation module comprises an open 3D structure.

[0045] The 3D structure may be a gyroid structure, as mentioned hereinabove.

[0046] The adaptation module may comprise at least two zones of different density.

[0047] The seat unit may comprise one or more additional standard modules. Such standard modules may be added to one or both of the seat cushion and the backrest. Additional standard modules may be made in the same or a different material compared to the basic seat cushion module and / or the basic backrest module. This adds to the number of variations possible for a wheelchair seat unit adapted to a user’s varying and specific needs.

[0048] In the following, the invention will be illustrated and explained by way of examples.

[0049] The accompanying drawings are described in detail below, where:

[0050] Fig. 1 shows a seat cushion and a backrest for a seat unit for a wheelchair;

[0051] Figs. 2a-2b show a 3D-print pattern;

[0052] Figs. 3-6 show different embodiments of a seat cushion for a seat unit for a wheelchair; and

[0053] Figs. 7-8 show different embodiments of a backrest for a seat unit for a wheelchair. Any position indications refer to the position shown in the Figures. In the Figures, same or corresponding elements are indicated with the same reference number. It must be understood that the Figures are principle sketches only. Relative proportions between elements in the Figures may be distorted.

[0054] Reference is first made to Figure 1 which shows a basic seat cushion module 1 and a basic backrest module 2 for a seat unit of a wheelchair.

[0055] The method comprises the steps of determining a user’s needs for support and pressure relief, and thereafter selecting such a basic seat cushion module 1 and basic backrest module 2 which makes the best starting position for manufacturing a seat unit for a wheelchair for a specific user.

[0056] It must be understood the basic seat cushion module 1 and the basic backrest module 2 may come in different sizes and shapes, and in a variety of materials, mainly different types of foam as described hereinabove.

[0057] Figure 1 shows one example of how the basic seat cushion module 1 and the basic backrest module 2 may shaped. In this example, the basic seat cushion module 1 has a top surface 11 which, in a position of use, faces in the direction of a user seated in the seat unit. In a front portion 13 of the top surface 11 , this seat cushion module 1 is provided with contouring 12 in the form of side supports 121 and a mid-support 122. The top surface 11 is in a rear portion 14 shown flat. In another embodiment, the rear portion 14 may also comprise contouring. In even another embodiment, the entire to surface 11 may be flat.

[0058] Figure 1 further shows the basic backrest module 2 having a front surface 21 which, in a position of use, faces in the direction of a user seated in the seat unit. This particular basic backrest module 2 is provided with contouring 22 in the form of side supports 22.

[0059] After having selected a suitable basic seat cushion module 1 and basic backrest module 2, the basic modules 1 , 2 may be adapted to properly tend to the user’s needs for support and pressure relief.

[0060] An adaptation module 4 for the seat cushion module, examples of which are shown in Figures 3-6 and / or an adaptation module 5 for the backrest module, examples of which are shown in Figures 7-8, may be 3D-printed. The 3D-printed adaptation module(s) 4, 5 are typically printed with an open 3D structure 3 illustrated in Figures 2a and 2b. The 3D structure 3 may for example be a gyroid structure. Fig. 2a shows a close-up of the pattern in one layer of a 3D structure, and Fig. 2b shows a layered 3D-structure in the shape of a cube for illustration purposes only.

[0061] Referring now to Figure 3, a basic seat cushion module 1 is shown comprising side supports 121 and a mid-support 122 in the front portion of the top surface. In this embodiment, in the rear portion, an adaptation module 4 has been provided. This is one example of how a basic seat cushion module may be modified in order to better adapt the seat unit of the wheelchair to the user.

[0062] Figure 4 shows another example of modification of a seat cushion module. Herein, the basic seat cushion module 1b is complemented in a front portion by a standard module 1b, as mentioned hereinabove. These two modules 1a, 1b may typically comprise different materials, such as foams of different density. The adaptation module 4 is placed in the same way as in the previous embodiment, namely in a rear portion of the top surface of the basic seat cushion module 1b.

[0063] In Figure 5, a different embodiment of the seat cushion is shown. Herein, the basic seat cushion module 1 is provided with the same contouring 12 as shown in the previous embodiments, including side supports 121 and mid-support 122 in the front portion of the top surface. However, in this embodiment a recess is provided in the rear portion of the top surface. The adaptation module 4 in this example is a 3D-printed cushion portion printed to the user’s need and for fitting into the recess of the basic seat cushion module 1.

[0064] Figure 6 shows another embodiment of the seat cushion, wherein the basic seat cushion module 1 is shown in the shape of a rectangular cuboid, similar to seat cushion module 1 b of Figure 4. The adaptation module 4 is provided over the entire top surface of the basic seat cushion module 1. In this embodiment, the adaptation module 4 is printed comprising contouring 42 including features like side supports 421 and a mid-support 422. It must be noted that in another embodiment, the adaptation module 4 may be provided over the entire top surface of the basic seat cushion module 1 and without any contouring.

[0065] An embodiment having a larger adaptation module 4 such as in the example of Figure 6, still makes the method according to the invention more affordable and quicker than a full seat unit in 3D print. Also, the basic seat cushion module beneath the 3D-printed adaptation module adds the beneficial features mentioned above regarding better pressure performance. In Figure 7 the basic backrest module 2 is shown as a rear portion of a complete backrest module. Covering the entire front surface of the basic backrest module 2, is an adaptation module 5. The adaptation module is 3D-printed with the open 3D structure 3 as shown in Figures 2a and 2b. The adaptation module 5 is here shown comprising contouring 52 in the form of side supports 52. In another embodiment, the adaptation module 5 may be without contouring and still cover the entire front surface of the basic backrest module 2. This depends on the needs of the user and how different density zones in the adaptation module 5 is used for providing the necessary pressure and pressure relief zones.

[0066] Figure 8 shows another embodiment of a backrest wherein the basic backrest module 2 is provided with side supports 22 and a recess or mid-portion wherein the adaptation module 5 is arranged. The adaptation module 5 is shown in an area which typically falls along the spine of the user. This is meant to illustrate how the adaptation module 5 can be made to address specific needs of the user.

[0067] The seat unit may comprise more than one adaptation module 4, 5. The seat unit may further comprise one or more additional standard seat cushion modules 1a and / or additional backrest modules (not shown).

[0068] The shown embodiments of seat cushions and backrests may be combined in a variety of ways. And it should be noted that the illustrations herein of possible ways to position adaptation modules 4, 5, are only examples. The adaptation modules 4, 5 may be sized, shaped, and placed in any way necessary to provide the best comfort for the user.

[0069] It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

[0070] Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

Claims

C l a i m s1. A method of manufacturing a seat unit for a wheelchair, the seat unit comprising a seat cushion and a backrest, the method comprising the steps of:- determining a user’s needs for support and pressure relief;- selecting a basic seat cushion module (1), the basic seat cushion module (1) having a top surface (11) facing the user in a position of use;- selecting a basic backrest module (2), the basic backrest module (2) having a front surface (21) facing the user in a position of use;- 3D-printing a seat unit adaptation module (4; 5) using information about the determined support and pressure relief needs of the user; and- arranging the adaptation module (4; 5) in connection with at least a portion of the top surface (11) of the basic seat cushion module (1) and / or a portion of the front surface (21) of the basic backrest module (2); wherein the adaptation module (4; 5) is printed with an open 3D structure (3).

2. The method according to claim 1, wherein the open 3D structure (3) is a gyroid structure.

3. The method according to claim 1 or claim 2, wherein the adaptation module (4; 5) comprises at least two zones of different density.

4. The method according to any one of the preceding claims, wherein the method further comprises the step of obtaining specific information about the user’s needs and / or measures.

5. The method according to claim 4, further including at least one of:- manually measuring the user;- preparing a mould of the user; and- scanning the user by means of a 3D-scanner.

6. The method according to any one of claims 1-5, wherein determining the user’s needs includes specifying in which areas of their body the user needs pressure and pressure relief, and wherein the at least two zones of different density of the adaptation module (4; 5), are adapted to said pressure and pressure relief areas.

7. The method according to any one of the preceding claims, further comprising the step of providing at least one of the basic seat cushion module (1) and the basic backrest module (2) with contouring (12; 22).

8. The method according to any one of the preceding claims, wherein the basic seat cushion module (1) and / or the basic backrest module (2) is / are made of foam.

9. A seat unit for a wheelchair, the seat unit comprising:- a basic seat cushion module (1) having a top surface (11) for facing a user in a position of use;- a basic backrest module (2) having a front surface (21) facing a user in a position of use; and- a seat unit adaptation module (4; 5) arranged in connection with at least a portion of the top surface (11) of the basic seat cushion module (1) and / or the front surface (21) of the basic backrest module (2); wherein the adaptation module (4; 5) comprises an open 3D-structure (3).

10. The seat unit according to claim 8, wherein the open 3D-structure (3) is a gyroid structure.11 . The seat unit according to claim 9 or claim 10, wherein the adaptation module (4; 5) comprises at least two zones of different density.

12. The seat unit according to any one of claims 9-11 , wherein the seat unit comprises one or more additional standard modules (1a; 1b).

13. The seat unit according to any one of claims 9-12, wherein at least one of the basic seat cushion module (1) and the basic backrest module (2) comprises contouring (12; 22).

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