CONNECTION MEANS WITH PREDETERMINED ANGULAR ALIGNMENT

Abstract

 The present invention discloses a connection means for connecting two parts with a predetermined angular alignment. The connection means comprises a first part (1) comprising a first surface (3) and a second surface (4), wherein the first surface (3) is a first reference surface. The connection means further comprises a second part (2) adapted to receive at least a portion of the first part (1) and comprising a third surface (5) and a fourth surface (6), wherein the third surface (5) is a second reference surface. At least one of the second and fourth surfaces (4, 6) is provided with at least one asymmetry feature, in particular in form of an inclination deviation and/or an elevated portion. When the first part (1) is inserted into the second part (2), the second and fourth surfaces (4, 6) contact each the asymmetry feature forces the first and second reference surfaces into close contact with each other such that the first and second reference surfaces determine the predetermined angular alignment of the first and second parts (1, 2).

Description

[0001] The present invention relates to a connection means for connecting two parts with a predetermined angular alignment using reference surfaces. With the connection means of the invention it is possible to provide a low cost but high precision angular alignment between the connected parts, as each part may comprise only one accurate reference surface. The invention further relates to a method for manufacturing a connection means as well as a wheelchair comprising the connection means, particularly for connecting drive wheels to a frame.

[0002] Known connection means for ensuring an angular alignment, e.g. for connecting a wheel directly or via additional mounting means to a frame, usually require high precision, i.e. little manufacturing tolerances, for all connection surfaces. This is true for both the surface quality as well as the surface inclination, if any. This is particularly true for a connection means for connecting a wheel to a frame, e.g. a drive wheel to a wheelchair frame, to ensure parallel alignment of the drive wheels. In the latter case manufacturing tolerances of +/- 0.5° could lead in a worst case scenario to drive wheels with a varying distance of up to 2 cm. This is unacceptable as it leads to undesired driving characteristics as well as irregular and excessive wear of the drive wheels.

[0003] It is therefore an object of the invention to provide a connection means for connecting two parts with a predetermined angular alignment with reduced manufacturing cost.

[0004] The idea of the invention is to determine the angular alignment of the two parts by use of reference surfaces. Each part of the connection means has at least one reference surface and when connecting the parts the reference surfaces contact each other thereby ensuring a high quality angular alignment. All other surfaces can be manufactured with reduced effort and higher manufacturing tolerances.

[0005] The connection means according to the invention is for connecting two parts with a predetermined angular alignment. The connection means comprises a first part with a first surface and a second surface, wherein the first surface is a first reference surface. Further, the connection means comprises a second part with a third surface and a fourth surface, wherein the third surface is a second reference surface and the second part is adapted to receive at least a portion of the first part. For example, the second part may have a substantially V-shaped or trapezoidal recess for receiving the first part, which is formed accordingly. The reference surfaces are preferably flat but may have any other shape like curved, wavelike or zigzag like. It is of utmost importance for the accurate angular alignment of the first and second parts that the reference surfaces are of adequate quality so that the reference surfaces match with the required degree of accuracy to achieve the desired angular alignment.

[0006] At least one of the second and fourth surface has an elevated portion, e.g. a smooth or edged convexly shaped surface, imparting the first and/or second part with an asymmetry feature. As an alternative or in addition to this asymmetry feature(s) there can be an inclination deviation such that the inclination of the first and second surfaces and/or the inclination of the third and forth surface differ from each other.

[0007] When the first part is inserted into the second part as far as possible, the second and fourth surfaces contact each other e.g. via the elevated portion(s) which forces the first and third surfaces, i.e. the reference surfaces, into close contact with each other, the first and third surfaces thereby providing the predetermined angular alignment of the first and second parts. The contact area of the first and third surfaces, i.e. the reference surfaces, must be enough to ensure a close contact so that the angular alignment is only determined by the reference surfaces.

[0008] In case the asymmetry feature is provided by an inclination difference, the difference can be in the region of up to +/- 15%. For example, the inclination of the first and second reference surfaces can each be determined to be 20°, such that the second surface might have a tolerance of -0.2° and/or the forth surface might have a tolerance of +0.2°.

[0009] The first and second parts of the connection means may provide a force-fit connection once assembled.

[0010] Preferably, the accuracy of the angular alignment of the first and second parts only depends on the accuracy of the first and third surfaces, which serve as reference surfaces. Hence, only these two reference surfaces should have a high quality surface, e.g. a precision of at least 1 mm or at least 0.5 mm or at least 0.1 mm or at least 0.05 mm or at least 0.01 mm or at least 5 µm or at least 1 µm or at least 0.5 µm. All other surfaces can be manufactured with a lower degree of accuracy which makes the production faster and cheaper. For economical reasons the number of reference surfaces should be as low as possible, but depending on material and use one may also use more than one reference surface per part, e.g. two or three reference surfaces for each of the first and the second part of the connection means. Also, the number of reference surfaces of the first and second part could be different. For example, the first or the second part could have two reference surfaces and the other part could have only one reference surface. In this way the assembly of the parts can be facilitated as the user does not have to pay attention to the relative orientation of the parts.

[0011] The first or the second part may comprise an axle mount on which a wheel, such as a drive wheel of a wheelchair, can be mounted. The axle mount may directly receive a wheel axle or comprise additional means for receiving a wheel axle such as a wheel axle of a drive wheel of a wheelchair. The other part, which does not comprise the axle mount, may comprises a mounting means for mounting the same to a frame structure such as a frame of a wheelchair or for mounting the same to a wheel mounting assembly which in turn is mounted to the frame of a wheelchair.

[0012] Also, both the first and the second part can be mounted on a frame structure. For example, the first part with an axle mount can be rotatably mounted on a frame, e.g. via a pin or a screw, and only the second part, which is also mounted on the frame, provides a specific angular alignment of the first part, e.g. of the wheel coupled to the axle mount. In this manner it can be ensured that two wheels, e.g. drive wheels of a wheelchair, are aligned mutually parallel.

[0013] The predetermined angular alignment may serve to ensure a certain camber and/or toe-in angel, particularly in combination with wheels, e.g., drive wheels of a wheel chair.

[0014] The first part and/or the second part may further comprise a fixation means for releasably fixing the first and second parts directly together. Any fixation means known to the skilled person can be used, such as screw, bolt, pin, quick pin and/or rivet. Also external fixation can be used, such as a clamp or screw clamp. This is also true for the fixation of the first and/or second parts to a frame.

[0015] The elevated portion may be convexly curved and can be formed by two flat surfaces with different angles to one another, wherein the intersection point may be rounded off. The elevated portion may also be formed by a rounded or curved surface, e.g. a convexly curved surface. The elevated portion can but does not have to cover the entire respective surface, but can be a small elevation only sufficient to meet its purpose. The elevation can also be provided by external parts, e.g. a bolt or screw inserted into the first and/or second part. The surfaces and/or the entire parts can be at least partly formed by milling.

[0016] A method for manufacturing a connection means for connecting two parts with a predetermined angular alignment comprises the following steps: providing a first part with a first surface and a second surface, wherein the first surface is a first reference surface; providing a second part with a third surface and a fourth surface, the second part being adapted to receive at least a portion of the first part, wherein the third surface is second reference surface. At least one of the second and fourth surface is provided with an asymmetry feature like e.g. an elevated portion. When the first part is inserted into the second part, the second and fourth surfaces contact each other via the elevated portion which forces the first and third surfaces, i.e. the reference surfaces, into contact with each other, the first and third surfaces providing the predetermined angular alignment of the first and second parts.

[0017] In the method, the surface comprising the elevated portion can be formed by milling.

[0018] A wheelchair comprises a frame and at least two drive wheels, wherein the drive wheels are connected to the frame via connection means according to the invention for ensuring that the wheels are mutually parallel.

[0019] These and other features of the invention will now be described by way of example with reference to the accompanying drawings, of which:

Figure 1a

is a schematic view of a connection means according to the invention;

Figure 1b

is an enlarged view of the second surface of the first part with an elevated portion;

Figure 2

is a schematic view of a connection means according to the invention assembled to a frame;

Figure 3

is a schematic cross sectional side view of a first part comprising an axle mount connected to a second part comprising an axle support via screws;

Figure 4

is a schematic perspective view showing a first part comprising an axle mount connected to a second part comprising an axle support;

Figure 5

is a schematic perspective view showing an exemplary first part of the invention;

Figure 6a

is a schematic side view of a wheelchair of the invention;

Figure 6b

is a schematic top view of a wheelchair of the invention;

Figure 6c

is a schematic back view of a wheelchair of the invention;

Figure 7

is a schematic top view of a wheelchair of the invention with connection means according to the invention.

[0020] The connection means as illustrated in figure 1 a shows a first part 1 which is at least partially inserted into a second part 2 as far as possible. The first part comprises a first surface 3 and a second surface 4, wherein the first surface 3 is a first reference surface. The second part 2 at least partially receives the first part 1 and has a third surface 5 as well as a fourth surface 6, wherein the third surface is a second reference surface. The connection means according to figure 1 has a substantially V-shaped or trapezoidal form. The first part 1 may not entirely enter into the second part 2 such that a head space 7 remains. The first part 1 may also comprise a head protrusion 8, e.g. of the same material as the first part 1 or of another material, e.g. rubber, which may contact a respective opposite surface of the second part 2.

[0021] As can be seen in figure 1, the first part 1 is received by the second part 2 and in an end position the second surface 4 of the first part 1 contacts the fourth surface 6 of the second part 2. An elevation of the second surface 4 ensures contact of the reference surfaces, namely the first surface 3 and the third surface 5. As can be seen, only the reference surfaces ensure the angular alignment of the first and second part 1, 2. Therefore, only the reference surfaces, namely first and third surfaces 3 and 5, have to be manufactured with a sufficient accuracy to achieve a certain angular alignment.

[0022] The second surface 4 is provided with the elevated portion as illustrated in figure 1b such that it becomes convexly curved over a length L. In particular, the second surface 4 may be formed by two substantially straight surfaces which are rounded with a radius R at an intersection point. With increasing convexity value a, a surface inclination angle W2 of the second part 2 should be equal to or greater than 90° to avoid manufacturing problems. The convexity value a should not come too close to zero to ensure that the elevated portion contacts the fourth surface 6 of the second part 2 at a predetermined location.

[0023] Figure 2 is a schematic view of a connection means according to the invention assembled to a frame 14. The first part 1 comprises an axle mount 11 for receiving a drive wheel axle 9 from a drive wheel 10. It is now of high importance to ensure the orientation of the drive wheel 10 relative to the frame 14. This is accomplished by the assembly of the two parts 1, 2 forming the connection means according to the invention. The first part 1 is mounted to the second part 2, i.e. a portion of the first part 1 is inserted into a respective recess of the second part 2. The first part 1 may be secured to the second part 2, e.g. by one or more screws or other equivalent means. In this way the reference surfaces contact each other and the angular alignment of the parts and therefore of the wheel 10 and the frame 11 is determined, as the second part 2 belongs to the frame 14 or is mounted to the frame 14. Figure 2 again shows the benefits of the invention, namely to have preferably only one reference surface for each of the first and second parts 1, 2. In contrast, manufacturing all surfaces, namely the first through the fourth surface 3 to 6, to fully contact the respective opposing surface is time and cost consuming. Nevertheless, due to unavoidable manufacturing tolerances the surface inclination angle W1 cannot be manufactured so that the first and second part 1, 2 perfectly match to one another. The invention provides a solution, namely two contacting reference surfaces and one surface with an elevated portion to ensure contact of the reference surfaces.

[0024] Figure 3 is a schematic cross sectional side view of a first part 1 comprising an axle mount 11, for receiving an axle 9 of a wheel 10, connected to a second part 2 comprising or forming part of an wheel mounting assembly 13. The first part 1 is releasably attached to the second part 2 by use of screws. The second part 2 may be part of a frame 14 to which a wheel 10 shall be mounted. With the setup as illustrated in figure 3 a predetermined angular alignment of the wheel 10 relative to the frame 14 can be ensured.

[0025] Figure 4 is a schematic perspective view showing a first part 1 comprising an axle mount 11 connected to the second part 2 comprising a wheel mounting assembly 13. A portion of the first part 1 is inserted into the recess of the second part 2 which is shaped to receive the first part 1. Both the first part and the second part comprise one reference surface which contact each other once the first part 1 is inserted into the second part 2 as far as possible. The parts may be fixed by one or more screws or other fixation means.

[0026] Figure 5 is a schematic perspective view showing an exemplary first part 1 of the invention. The first part comprises a first surface 3, which is flat and serves as a reference surface, and a second surface 4 with an elevated portion. Two flat portions of the second surface 4 of the second surface 4 have an angle of 182° to one another to provide a convexly curved surface.

[0027] Figure 6a is a schematic side view of a wheelchair 12 of the invention without a seat and backrest. The wheelchair 12 comprises a frame 14 and two drive wheels 10 each attached via a drive wheel axle 9 to an axle mount 11 which in turn is secured to the frame 14 via a wheel mounting assembly 13. Figures 6c and 6b show a schematic top and back view, respectively, of a wheelchair of the invention showing the parallel alignment of the drive wheels 10. The wheelchair 12 as illustrated in Figure 7 comprises connection means according to the invention to ensure mutual parallel alignment of the drive wheels 10. Therefore, the wheelchair 12 comprises one connection means for each of the wheels 10.

[0028] The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, as appropriate, may, separately, or in any combination of such features, be utilized for realizing the invention in diverse forms thereof.

Reference Signs

[0029] 

1

first part of connection means

2

second part of connection means

3

first surface of first part

4

second surface of first part

5

third surface of second part

6

fourth surface of second part

7

headspace

8

head protrusion of first part

9

drive wheel axle

10

drive wheel

11

axle mount

12

wheelchair

13

wheel mounting assembly

14

frame

a

convexity value

L

length

R

radius of convexity

W1

surface inclination angle

W2

surface inclination angle

Claims

1. A connection means for connecting two parts with a predetermined angular alignment, the connection means comprising:

a first part (1) comprising a first surface (3) and a second surface (4), wherein the first surface (3) is a first reference surface;

a second part (2) adapted to receive at least a portion of the first part (1) and comprising a third surface (5) and a fourth surface (6), wherein the third surface (5) is a second reference surface,

wherein at least one of the second and fourth surfaces (4, 6) is provided with at least one asymmetry feature, in particular in form of an inclination deviation and/or an elevated portion, and

wherein when the first part (1) is inserted into the second part (2), the second and fourth surfaces (4, 6) contact each other with the asymmetry feature forcing the first and second reference surfaces into close contact with each other, and the first and second reference surfaces determining the predetermined angular alignment of the first and second parts (1, 2).

2. The connection means of claim 1, wherein the accuracy of the angular alignment of the first and second parts (1, 2) only depends on the accuracy of the first and second reference surfaces, with preferably the first and second reference surfaces being flat.

3. The connection means of claim 1 or 2, wherein the first or the second part (1, 2) comprises an axle mount (11).

4. The connection means of claim 3, wherein the other of the first or second part (1, 2) comprises a mounting means for mounting the same to a frame structure, optionally a frame (14) of a wheelchair (12).

5. The connection means of any of the preceding claims, wherein the predetermined angel is a camber and/or toe-in angel.

6. The connection means of any of the preceding claims, wherein the first part (1) and/or the second part (2) further comprise a fixation means for releasably fixing the first and second parts (1, 2) together.

7. The connection means of any of the preceding claims, wherein the elevated portion is formed by two flat surfaces with different angles to one another, with the intersection point preferably being rounded off, or
the elevated portion is formed by a rounded and/or curved surface.

8. The connection means of any of the preceding claims, wherein the inclination deviation of the second surface is up to -15%, and/or the inclination deviation of the forth surface is up to +15%.

9. Method for manufacturing a connection means for connecting two parts with a predetermined angular alignment, the method comprising the following steps:

providing a first part (1) with a first surface (3) and a second surface (4), wherein the first surface (3) is a first reference surface;

providing a second part (2) with a third surface (5) and a fourth surface (6), the second part (2) being adapted to receive at least a portion of the first part (1), wherein the third surface (5) is a second reference surface,

wherein at least one of the second and fourth surfaces (4, 6) is provided with at least one asymmetry feature, in particular in form of an inclination deviation and/or an elevated portion, and

wherein when the first part (1) is inserted into the second part (2), the second and fourth surfaces (4, 6) contact each other with the asymmetry feature forcing the first and second reference surfaces into close contact with each other, and the first and second reference surfaces determining the predetermined angular alignment of the first and second parts (1, 2).

10. Method for manufacturing a connection means of claim 9, wherein the surface comprising the elevated portion is formed by milling.

11. Wheelchair (12) with a frame (14) and two drive wheels (10), wherein the drive wheels (10) are connected to the frame (14) via connection means of any of claims 1 to 8.

Drawing