TIRE TESTING STAND WITH A HEXAPOD ARRANGEMENT AND A BELT

Description

[0001] The present invention relates to a tire testing stand.

[0002] Tire testing stands are known from the prior art. These tire testing stands usually have a frame and a tire holder. A tire with a tread can be mounted on the tire holder so that it can rotate around its axis of rotation. Because the tire is mounted rotatably on the tire holder, it can be moved into different positions relative to the frame.

[0003] In the prior art of tire testing stands, a rolling surface unit is provided with a rolling surface that can be moved relative to the frame. The rolling surface of the rolling surface unit can also be referred to as a road substitute and is designed to approximate road conditions. The rolling surface unit can, for example, be formed by a rotatably mounted drum of the tire testing stand, and the rolling surface can be formed by a circumferential outer surface of the drum.

[0004] If the tire is rotatably mounted on the tire holder, it can be brought into a contact position where the tire's tread and the drum's outer surface are in contact. When the tire and the drum's outer surface are in contact and the outer surface is moved relative to the tire, the tire can roll on the outer surface. Such a tire test stand is known from DE 10 2009 002169 A1.

[0005] In general, it is desirable that a tire test bench can be used to simulate the tire's reaction to different load conditions and the chassis kinematics when driving on a road particularly well.

[0006] It is therefore an object of the present invention to replicate the reaction of the tire to different load conditions of the tire and the chassis kinematics when driving on a road particularly well.

[0007] According to the invention, the aforementioned problem is solved by a tire test stand with the features of claim 1. The tire test stand comprises a frame. Furthermore, the tire test stand comprises a tire holder. The tire test stand also comprises a hexapod arrangement with six linear drive elements. Each of the six linear drive elements is attached at one end to the frame and at the other end to the tire holder. A tire with a tread can be rotatably mounted on the tire holder about its axis of rotation. The tire test stand also comprises a belt. Furthermore, the tire test stand comprises two rotatably mounted guide rollers. The guide rollers are partially enclosed by the belt, so that the belt forms a flat belt section between the guide rollers.When the tire is rotatably mounted on the tire holder, the linear drive elements of the hexapod assembly can be adjusted to bring the tire into contact. In this contact position, the tire tread and the flat belt section are in contact. Furthermore, when the tire and the flat belt section are in contact and the belt is moved relative to the tire, the tire rolls along the flat belt section. The tire test stand features a tire drive unit that, when the tire is rotatably mounted on the tire holder, can drive it in one direction of rotation.

[0008] The tire test stand has a frame. Various components of the tire test stand can be attached to the frame, such as the first end of each of the six linear drive elements. Other components of the tire test stand that can be attached to the frame include the two rotatably mounted guide rollers. Furthermore, a control element for operating the tire test stand can be attached to the frame as part of the various components.

[0009] Furthermore, the tire test stand features a tire holder. A tire can be mounted on the tire holder so that it can rotate around its axis of rotation.

[0010] Furthermore, the tire test stand features a hexapod arrangement with six linear drive elements. In particular, the length of each of the six linear drive elements can be adjusted. The hexapod arrangement can be described as a parallel kinematic system. One advantage of the hexapod arrangement is its ability to achieve high rigidity in a comparatively small footprint compared to conventional adjustment units designed as serial kinematics. The hexapod arrangement also offers the advantage of high positioning accuracy compared to conventional adjustment units designed as serial kinematics. Specifically, the hexapod arrangement allows the tire to be moved into different positions, such as the contact position, with high precision compared to conventional adjustment units designed as serial kinematics.In connection with the present invention, it has surprisingly turned out that the hexapod arrangement, in particular in combination with the flat belt section, can replicate the real chassis kinematics of a vehicle in a test environment better than the tire test stands known from the prior art.

[0011] Each of the six linear drive elements is attached at one end to the frame and at the other end to the tire holder. The six linear drive elements can be described as acting parallel to each other between the frame and the tire holder, so the hexapod arrangement can be described as a parallel kinematic system. In particular, by adjusting the linear drive elements, the tire holder can be moved relative to the frame and positioned in different ways. Preferably, each of the six linear drive elements is pivotably attached at its first end to the frame and at its second end to the tire holder, so that each linear drive element can assume different orientations by adjusting and pivoting relative to the frame and the tire holder.

[0012] The tire holder allows the tire to be mounted so that its tread can rotate around its axis of rotation. Therefore, a tire can be mounted on the tire holder, or it can be left unmounted. Specifically, because the linear drive elements allow the tire holder to be moved relative to the frame and positioned in different ways, a tire mounted on the tire holder can be moved relative to the frame and positioned in different ways by adjusting these linear drive elements.

[0013] The tire test stand also includes a belt. The belt can also be referred to as an endless belt or strap. Preferably, the belt is designed to transmit tensile force. In particular, the belt is closed in its longitudinal direction, so that the ends of the belt arranged longitudinally are connected to each other or merge seamlessly.

[0014] Furthermore, the tire test stand features two rotatably mounted deflection rollers. These two deflection rollers can be rotatably mounted on the frame.

[0015] The pulleys are partially wrapped by the belt, so that the belt forms a flat section between the pulleys. The belt can have a first run and a second run. The first run can be called the working run and can extend from the first pulley to the second pulley. The second run can be called the slack run and can extend from the first pulley to the second pulley. The flat section of the belt can form a portion of the first run. The belt can move in a straight line in one direction of rotation within the area of ​​the first run, thus forming the flat section. The flat section of the belt is planar.Preferably, the flat belt section extends along a tangential plane on the belt, in which a contact point between the tread and the flat belt section lies, when the tire is rotatably mounted on the tire holder and the tire tread and the flat belt section are in contact. The flatness of the belt section ensures that the tire can roll on a flat rolling surface. A flat rolling surface formed by the flat belt section is particularly advantageous compared to a rolling surface curved by a circumferential outer surface of the drum, since the flat belt section can replicate a real road, especially its flat shape, better than tire test rigs known from the prior art, particularly those with a rolling surface formed by a circumferential outer surface of a drum.In particular, it was found that the rolling resistance of the tire when rolling on the flat belt section could be significantly reduced compared to a curved rolling surface. Furthermore, the combination of belt and idler pulleys offers a space-saving rolling surface compared to a rolling surface on a drum that is large enough to reduce curvature.

[0016] When the tire is rotatably mounted on the tire holder, it can be moved into a contact position by adjusting the linear drive elements of the hexapod assembly. As previously described, the tire can be moved relative to the frame and into different positions by adjusting the linear drive elements of the tire holder. Specifically, the tire can be moved into the contact position by adjusting the linear drive elements of the hexapod assembly. In the contact position, the tire's tread and the flat belt section are in contact.Preferably, the tire can be moved into further contact positions by adjusting the linear drive elements of the hexapod arrangement, so that, for example, a camber of the tire, a skew of the tire, a tire load of the tire, in particular perpendicular to the tangential plane on the belt in which the contact point between the tread and the flat belt section is located, and / or the position of the tire relative to the flat belt section, in particular parallel to the tangential plane on the belt in which the contact point between the tread and the flat belt section is located, and perpendicular to the belt rotation direction in the area of ​​the flat belt section and / or parallel to the belt rotation direction in the area of ​​the flat belt section, can be set.

[0017] When the tire and the flat belt section are in contact and the belt is moved relative to the tire, the tire continues to roll on the flat belt section. Preferably, the flat belt section forms a flat rolling surface on which the tire can roll. As already described, the tire can be moved to additional contact positions by adjusting the linear drive elements of the hexapod assembly. When the tire rolls on the flat belt section, it can be subjected to different load conditions during rolling.For example, when the tire rolls on the flat belt section, the camber of the tire, the skew of the tire, the tire load of the tire, in particular perpendicular to the tangential plane on the belt in which the contact point between the tread and the flat belt section is located, and / or the position of the tire relative to the flat belt section, in particular parallel to the tangential plane on the belt in which the contact point between the tread and the flat belt section is located, and perpendicular to the belt rotation direction in the area of ​​the flat belt section and / or parallel to the belt rotation direction in the area of ​​the flat belt section, can be adjusted.

[0018] In the context of tire test benches, it has become apparent that a person skilled in the art would, from a technical perspective, avoid using a flat rolling surface. For example, they would not use a belt because the forces acting on the belt due to the different load states of the tire are extremely complex. When the belt is moved, it risks slipping off the pulleys, particularly due to forces acting perpendicular to the direction of rotation, unless technically complex and costly precautions are taken. Therefore, tire test benches known from the prior art use drums with curved rolling surfaces.However, in connection with the present invention, it has become apparent that the combination of hexapod arrangement and flat belt section justifies the increased technical complexity and increased costs, since this combination is surprisingly able to replicate the real chassis kinematics when driving on a road particularly well.

[0019] Furthermore, in connection with tire test benches, it has become apparent that a person skilled in the art would refrain from using a hexapod arrangement from a technical point of view, since the hexapod arrangements known from the prior art, for example, exhibit low stiffness in directions due to their symmetrical structure, which is disadvantageous for testing tires that are subjected to different load states during rolling. Therefore, when measuring the reaction forces of the tire in response to the different load states, the low stiffness and the unfavorable deformation of the hexapod arrangement must be taken into account and, for example, factored out.For example, due to the symmetrical design of the hexapod arrangements known from the prior art, it is not possible to arrange the linear drive elements in such a way that at least three of the six linear drive elements are arranged such that when a first linear drive element of the three linear drive elements exerts a force on the tire, the largest force component of this force is oriented in the direction of the first spatial direction of the three spatial directions, when a second linear drive element of the three linear drive elements exerts a force on the tire, the largest force component of this force is oriented in the direction of the second spatial direction of the three spatial directions, and when a third linear drive element of the three linear drive elements exerts a force on the tire, the largest force component of this force is oriented in the direction of the third spatial direction of the three spatial directions.Therefore, the tire test rigs known from the prior art relate to serial kinematics, in which the force directions applied to the tire in all three spatial directions can be realized by relatively simple technical means at comparatively low cost. However, in connection with the present invention, it has become apparent that the combination of a hexapod arrangement and a flat belt section justifies the increased technical complexity and higher costs, since this combination can surprisingly replicate the real chassis kinematics when driving on a road particularly well.

[0020] In connection with the present invention, it has been surprisingly found, when measuring the tire's reaction forces in response to different load conditions, that when the tire rolls on the flat belt section using a hexapod arrangement, the tire's reaction to the different load conditions corresponds more closely to the reaction of a tire when used on a real road than is the case with tire test benches known from the prior art. In particular, it has been found that the combination of the hexapod arrangement and the flat belt section allows for a particularly accurate simulation of real-world chassis kinematics when driving on a road.

[0021] In summary, it can be stated that the tire test bench is particularly good at simulating the tire's reaction to different load conditions and the chassis kinematics when driving on a road.

[0022] In one embodiment, at least one of the linear drive elements of the hexapod arrangement is designed as a hydraulic cylinder. Designing at least one of the linear drive elements of the hexapod arrangement as a hydraulic cylinder ensures that comparatively high forces can be transmitted. Furthermore, designing at least one of the linear drive elements of the hexapod arrangement as a hydraulic cylinder ensures uniform and precise positioning movements. In particular, designing at least one of the linear drive elements of the hexapod arrangement as a hydraulic cylinder increases the positioning accuracy of the hexapod arrangement. Preferably, each of the linear drive elements of the hexapod arrangement is designed as a hydraulic cylinder. The advantages mentioned for the at least one linear drive element apply accordingly to each of the linear drive elements.

[0023] In one embodiment, at least one of the linear drive elements of the hexapod arrangement is designed as an electromechanical linear drive. Designing at least one of the linear drive elements of the hexapod arrangement as an electromechanical linear drive ensures comparatively high adjustment speeds and high adjustment accelerations for adjusting the linear drive elements. Furthermore, designing at least one of the linear drive elements of the hexapod arrangement as an electromechanical linear drive ensures uniform and precise adjustment movements. In particular, designing at least one of the linear drive elements of the hexapod arrangement as an electromechanical linear drive increases the positioning accuracy of the hexapod arrangement. Preferably, each of the linear drive elements of the hexapod arrangement is designed as an electromechanical linear drive.The advantages mentioned for at least one linear drive element apply accordingly to each of the linear drive elements.

[0024] The tire test stand features a tire drive unit which, when the tire is rotatably mounted on the tire holder, can drive it in one direction of rotation. The tire drive unit allows the tire to be driven in its direction of rotation, thus setting it into a rotational motion around its axis. Furthermore, the tire drive unit can accelerate the tire as it rolls along the flat belt section in its direction of rotation, thereby subjecting the tire to a further load. If the tire test stand does not have a belt drive unit, the belt can be driven in its direction of rotation by driving the tire in its direction of rotation and ensuring contact between the tread and the flat belt section.

[0025] In one embodiment, the tire test stand includes a tire braking unit which, when the tire is rotatably mounted on the tire holder, can brake it in one direction of rotation. The tire braking unit slows the tire in its direction of rotation, thus reducing its rotational speed around its axis. Furthermore, the tire braking unit can also brake the tire as it rolls along the flat belt section in its direction of rotation, allowing the tire to be subjected to a further load.

[0026] In one embodiment, the tire test stand has a belt drive unit that can drive the belt in one direction of rotation. The belt can be driven in this direction by means of the belt drive unit. If the tire test stand does not have a tire drive unit, the tire can be driven in this direction by driving the belt in the direction of rotation and by maintaining contact between the tread and the flat section of the belt.

[0027] In one embodiment, the belt drive unit is coupled to one of the pulleys to drive the belt in the direction of belt rotation. This coupling provides a technically simple and cost-effective belt drive, as it eliminates the need for additional components to connect the drive unit to the belt. Preferably, the belt drive unit is coupled to two of the pulleys to drive the belt in the direction of belt rotation.A coupling of the belt drive unit with two deflection pulleys to drive the belt in the direction of belt rotation via these deflection pulleys ensures that the force is introduced into the belt at several points to drive it, thus reducing the mechanical stress on the belt.

[0028] Further features, advantages, and applications of the present invention will become apparent from the following description of the exemplary embodiments and the figures. All features described and / or illustrated, individually and in any combination, constitute the subject matter of the invention, irrespective of their composition in the individual claims or their cross-references. In the figures, the same reference numerals denote identical or similar objects. Figure 1 shows a schematic view of an embodiment of a tire test stand according to the invention.

[0029] In Figure 1 Figure 1 shows a schematic view of an embodiment of a tire test stand 1 according to the invention. Figure 2 further shows Figure 1 an operator 3 of the tire testing stand 1.

[0030] The tire test stand 1 comprises a frame 5, a tire holder 7, a hexapod assembly 9, a belt 11, and two deflection pulleys 13. Furthermore, the tire test stand 1 comprises a tire drive unit 15, a tire braking unit 17, and a belt drive unit 19.

[0031] The hexapod assembly 9 has six linear drive elements 21. Each of the six linear drive elements 21 has a first end 23 and a second end 25. Each of the six linear drive elements 21 is attached to the frame 5 at its first end 23 and to the tire holder 7 at its second end 25. A section of the frame 5 extends into the rear part of the Figure 1 and is from the one in Figure 1The section of frame 5 shown is obscured. Three of the six linear drive elements 21 are connected at their first end 23 to the section shown in Figure 1 The section of frame 5 shown is attached. Three more of the six linear drive elements 21 are attached with their first end 23 to the section shown in Figure 1 concealed section of frame 5. Each of the six linear drive elements 21 is encased by a bellows to protect the linear drive element 21 from contamination. In the Figure 1 In the illustrated embodiment of the tire test stand 1 according to the invention, each of the six linear drive elements 21 of the hexapod arrangement 9 is designed as an electromechanical linear drive. Alternatively, by conversion, each of the six linear drive elements 21 of the hexapod arrangement 9 can also be designed as a hydraulic cylinder.

[0032] Furthermore, in Figure 1A tire 27 with a tread 29 is shown. The tire 27 is rotatably mounted on the tire holder 7 about its axis of rotation 31. The tire drive unit 15 can drive the tire 27, rotatably mounted on the tire holder 7, in one direction of tire rotation Re. The tire brake unit 17 can brake the tire 27, rotatably mounted on the tire holder 7, in the direction of tire rotation Re, i.e., reduce the rotational speed of the tire 27 in the direction of tire rotation Re.

[0033] As already mentioned, the tire test stand 1 has the belt 11 and the two guide rollers 13. The two guide rollers 13 are rotatably mounted. The guide rollers 13 are partially wrapped by the belt 11, so that the belt 11 forms a flat belt section 33 between the guide rollers 13. The tire 27, which is rotatably mounted on the tire holder 7, can be moved into a contact position by adjusting the linear drive elements 21 of the hexapod assembly 9, which is in Figure 1 is shown and in which the tread surface 29 of the tire 27 and the flat belt section 33 are in contact.

[0034] As already described, the tire test stand 1 has the belt drive unit 19. The belt drive unit 19 can drive the belt 11 in one belt rotation direction Ri. In the Figure 1 In the illustrated embodiment of the tire test stand 1 according to the invention, the belt drive unit 19 with the in Figure 1 The deflection pulley 13 shown on the left is coupled to the deflection pulleys 13 to drive the belt 11 via this deflection pulley 13 in the belt rotation direction Ri. When the tire 27 and the flat belt section 33 are in contact and the belt 11 is moved relative to the tire 27, the tire 27 rolls on the flat belt section 33.

[0035] In the Figure 1In the illustrated embodiment, the tire 27 can be positioned relative to the flat belt section 33 using the hexapod assembly 9. Specifically, the tire 27 can be moved into the contact position, where the tread 29 of the tire 27 is in contact with the flat belt section 33, by adjusting the linear drive elements 21 of the hexapod assembly 9. Furthermore, the tire 27 can be moved into additional contact positions, where the tread 29 of the tire 27 is also in contact with the flat belt section 33, by adjusting the linear drive elements 21 of the hexapod assembly 9. As the tire 27 rolls on the flat belt section 33, it is subjected to different load conditions.By adjusting the linear drive elements 21 as the tire 27 rolls on the flat belt section 33, the camber of the tire 27, the skew of the tire 27, the tire load of the tire 27, and / or the position of the tire 27 relative to the flat belt section 33 can be adjusted. Furthermore, the tire 27 can be driven in the direction of tire rotation Re using the tire drive unit 15 or braked in the direction of tire rotation Re using the tire brake unit 17. This allows the tire 27 to be subjected to different load conditions as it rolls.

[0036] In connection with the present invention, when measuring the reaction forces of the tire 27 in response to different load conditions, it was surprisingly found that when the tire 27 rolled on the flat belt section 33 using the hexapod arrangement 9, the tire's reaction to the different load conditions corresponds more closely to the reaction of a tire when used on a real road than is the case with tire test benches known from the prior art. In particular, it was found that the combination of the hexapod arrangement 9 and the flat belt section 33 allows for a particularly accurate simulation of the real chassis kinematics when driving on a road.

[0037] It should be further noted that "having" does not exclude any other elements or steps, and "a" or "an" does not exclude a plurality. It should also be noted that features described with reference to one of the above embodiments may also be used in combination with other features of other embodiments described above. Reference numerals in the claims are not to be considered as a limitation. Reference sign

[0038] 1 Tire test stand 3 Operator 5 Frame 7 Tire holder 9 Hexapod assembly 11 Belt 13 Deflection pulley 15 Tire drive unit 17 Tire braking unit 19 Belt drive unit 21 Linear drive element 23 First end of a linear drive element 25 Second end of a linear drive element 27 Tire 29 Tread 31 Axis of rotation 33 Flat belt section Re Tire rotation direction Ri Belt rotation direction

Claims

1. Tire test stand (1) with a frame (5), with a tire holder (7), with a hexapod assembly (9) with six linear drive elements (21), each of the six linear drive elements (21) being attached at a first end (23) to the frame (5) and at a second end (25) to the tire holder (7), wherein a tire (27) with a tread (29) can be attached to the tire holder (7) so as to be rotatable about its axis of rotation (31), with a belt (11), and with two rotatably mounted deflection pulleys (13), the deflection pulleys (13) being partially looped around by the belt (11) such that the belt (11) forms a flat belt portion (33) between the deflection pulleys (13), wherein when the tire (27) is rotatably attached to the tire holder (7), the tire (27) can be brought by adjustment of the linear drive elements (21) of the hexapod assembly (9) into a contact position in which the tread (29) of the tire (27) and the flat belt portion (33) are in contact, wherein when the tire (27) and the flat belt portion (33) are in contact and the belt (11) is moved in relation to the tire (27), the tire (27) rolls on the flat belt portion (33), and wherein the tire test stand (1) has a tire drive unit (15) which, when the tire (27) is rotatably attached to the tire holder (7), can drive said tire in a tire revolving direction (Re).

2. Tire test stand (1) according to the preceding claim, wherein at least one of the linear drive elements (21) of the hexapod assembly (9) is designed as a hydraulic cylinder.

3. Tire test stand (1) according to Claim 1, wherein at least one of the linear drive elements (21) of the hexapod assembly (9) is designed as an electromechanical linear drive.

4. Tire test stand (1) according to one of the preceding claims, wherein the tire test stand has a tire braking unit (17) which, when the tire (27) is rotatably attached to the tire holder (7), can brake said tire in a tire revolving direction (Re).

5. Tire test stand (1) according to one of the preceding claims, wherein the tire test stand (1) has a belt drive unit (19) which can drive the belt (11) in a belt revolving direction (Ri).

6. Tire test stand (1) according to Claim 5, wherein the belt drive unit (19) is coupled to one deflection pulley (13) of the deflection pulleys (13) in order to drive the belt (11) in the belt revolving direction via said deflection pulley (13).