WO2005116638A1

WO2005116638A1 - Apparatus for testing a tyre and/or road surface

Info

Publication number: WO2005116638A1
Application number: PCT/AU2005/000742
Authority: WO
Inventors: Steven Edwin Cooper; Nick Koikas
Original assignee: Better Loggers Pty Ltd
Priority date: 2004-05-27
Filing date: 2005-05-25
Publication date: 2005-12-08

Abstract

An apparatus (1) for testing a tyre and/or road surface has a first wheel (2) mounted for rotation about a first axis (3). The first wheel (2) is adapted to receive a tyre (12). A second wheel (13) is mounted for rotation about a second axis (14). The second axis (14) is substantially parallel to the first axis (3). The second wheel (13) has a circumferential peripheral surface (29) adapted to receive a layer of road surface material (30). A drive motor (8) rotatably drives one of the first and second wheels (2, 13). The second axis (14) is displaceable relative to the first axis (3) for engaging the tyre (12) with the road surface material (30) in use.

Description

Apparatus for Testing a Tyre and/or Road Surface Field of the Invention

The present invention relates to testing of tyres and road surfaces, and in particular relates to, but is not limited to, apparatus for the testing of noise generated by the interaction of a tyre and road surface.

Background of the Invention

Road authorities spend vast amounts of money on main arterial roads and freeways in order to reduce the noise generated by the interaction of the road surface and vehicle tyres passing over the road surface. The difference in noise generated between one road surface and another can be up to 10 dB(A). This difference in noise would be subjectively perceived by a person with normal hearing to be approximately half as loud (or, conversely, twice as loud). It is thus important to quantify noise generated from road surfaces so as to assess the quality of road, however current test procedures used to quantify both the overall noise level and spectral noise level characteristics from the interaction of rubber tyres on road surfaces introduce various extraneous noise sources. Typical extraneous noise sources include noise from engines, transmissions, exhaust stacks/mufflers, wind turbulence and vehicular carriage rumble. The influence of such extraneous noise sources can lead to incorrect tyre/road surface noise results, such that the current test procedures are not scientifically rigorous or repeatable. One current test procedure involves the monitoring of noise adjacent to two different sections of road surface that are subject to the same stream of road traffic. One microphone is placed adjacent to the first section of road surface, which acts as a reference surface, at a known distance away from the stream of traffic. A further microphone is placed adjacent to the second section of road surface, being the specific road surface being tested, at the same distance from the stream of traffic. On the assumption that both sections of road surface are subjected to identical traffic composition and speed, and extraneous noise levels, the results from the two sections are compared, thereby giving an indication of the quality of the test surface as compared to the reference surface. Even when the two sections of road surface are located in the same thoroughfare, however, there can often be significant variations in the volume of traffic, the speed of the same vehicles, and the effects of extraneous noise from the vehicles, the effects of wind such as the rustling of leaves, precipitation and industrial and domestic noise disturbances. The noise metric used to quantify road surface/tyre noise interaction utilising this method is the Leq. This is the continuous equivalent noise level. It is a logarithmic average of every instantaneous sound pressure level integrated over a time constant for a minimum measurement period of normally 15 minutes. During this period, maximum noise emissions from trucks, horns or non-typical vehicular noise sources can significantly effect the continuous equivalent noise level. These extraneous noise sources are therefore undesirable for the quantification of tyre/road surface noise measurements and can bias test results, or invalidate such testing. The test sections of road surface are often tested several times, a few weeks after laying the road surface, six months, twelve months and two years after laying the road surface. Over this period, however, the road surface may become uneven due to work undertaken by local government, electricity or water authorities. Another variable is thus introduced which has the effect of introducing unwanted extraneous noise sources from vehicles traversing over the now changed road surface. In another current test procedure for quantifying noise generated by interaction of a tyre and road surface, microphones are mounted on a trailer behind a vehicle. Noise levels are then measured whilst the vehicle is traversing over the test road surface. Road surface unevenness will, however, typically produce unwanted vehicular carriage noise from the trailer when utilising such a method. The noise of other vehicles passing by can also significantly effect noise readings. Further, wind noise acting on the microphone can also effect the noise readings, particularly when testing at high speeds. A further problem associated with these current procedures is the requirement to lay a significant length of experimental road surface, which can be relatively expensive. Also, whilst some of the extraneous noises associated with the presently available test procedures might be reduced or eliminated by utilising dedicated test roads laid in isolation from surrounding noise sources, the provision of such dedicated and isolated test roads is typically prohibitively expensive. Object of the Invention

It is an object of the present invention to overcome or substantially ameliorate at least one of the above disadvantages. Summary of the Invention

There is disclosed herein an apparatus for testing a tyre and/or road surface, said apparatus comprising: a first wheel mounted for rotation about a first axis and being adapted to receive a tyre; a second wheel mounted for rotation about a second axis, said second axis being substantially parallel to said first axis, said second wheel having a circumferential peripheral surface adapted to receive a layer of road surface material; and a drive motor for rotatably driving one of said first and second wheels; wherein said second axis is displaceable relative to said first axis for engaging the tyre with the road surface material in use. The apparatus may further comprise the tyre mounted on said first wheel. The apparatus may also comprise the layer of road surface material mounted on said second wheel circumferential peripheral surface. The apparatus may further comprise a first axle rotatable about said first axis and a first wheel mount fixed in relation to said first axle, said first wheel being mounted on said first wheel mount. The apparatus may further comprise a second axle rotatable about said second axis and a second wheel mount fixed in relation to said second axle, said second wheel being mounted on said second wheel mount. Typically, said drive motor is arranged to rotatably drive said first wheel. In one form, said first axis is fixed and said second axis is displaceable. The apparatus may further comprise an engagement drive for displacing said second axis relative to said first axis for engaging the tyre with the road surface in use. The apparatus may further comprise one or more microphones located adjacent an interface between the tyre and the road surface material when the tyre is engaged with the road surface material. The drive motor may be acoustically shielded. There is further disclosed herein a method of testing a- tyre and/or road surface comprising the steps of: mounting a tyre on a first wheel, said first wheel being rotatable about a first axis; laying a road surface material on a circumferential peripheral surface of a second wheel, said second wheel being rotatable about a second axis; displacing said second axis with respect to said first axis to thereby engage said tyre and said road surface material; and rotatably driving one of said first and second wheels. In one form, said method further comprises the step of measuring noise generated by the interaction of said tyre and said road surface.

Brief Description of the Drawings

A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings, wherein: Figure 1 is a front perspective view of a tyre and/or road surface testing machine. Figure 2 is a rear perspective view of the tyre and/or road surface testing machine of Figure 1, including a layer of test road material. Figure 3 is a front perspective view of the tyre and/or road surface testing machine of Figure 1 with the wheels removed. Figure 4 is a plan view of the tyre and/or road surface testing machine of Figure 1. Figure 5 is a front elevation view of the tyre and/or road surface testing machine of Figure 1. Figure 6 is a right side elevation view of the first wheel and stand of the tyre and/or road surface testing machine of Figure 1. Figure 7 is a rear elevation of the second wheel and stand of the tyre and/or road surface testing machine of Figure 1. Figure 8 is a left side elevation view of the second wheel and stand of Figure 7, including a layer of test road material. Detailed Description of the Drawings

Referring to the accompanying drawings, there is depicted an apparatus for testing a tyre and/or road surface in the form of a tyre and/or road surface testing machine 1. The testing machine 1 includes a first wheel 2 mounted for rotation about a first axis 3. The first wheel 2, in the form of a standard automotive rim, is mounted on a first wheel mount 4, here in the form of a wheel mounting flange 4, utilising wheel bolts in the usual manner. The first wheel mount 4 is fixed in relation to a first axle 5 that is rotatable about the first axis 3. The first axle 5 is mounted on a first stand 6 by way of bearing blocks 7. A drive motor 8 is coupled to the first axle 5 by way of mating drive flanges 9, 10 for rotatably driving the first wheel 2. The drive motor 8 is mounted on a bracket 11 fastened to the first stand 7. The first wheel 2 is.adapted to receive a tyre 12 in the usual manner. A second wheel 13 is mounted for rotation about a second axis 14. Here the second wheel 13 is mounted on a second wheel mount 15, in the form of a wheel mounting flange 15, utilising wheel bolts. The second wheel mount 13 is fixed in relation to a second axle 16 that is rotatable about the second axis 14. The second axle 16 (and therefore the second axis 14) is parallel, to the first axle 5 (and therefore the first axis 3). The second axle 16 is displaceable relative to the first axle 5. The second axle 16 is displaceable by virtue of being mounted on a plate 17 that is slidably mounted on a second stand 18. The plate 17 has been omitted from Figure 2 for clarity purposes. The second axle 16 is mounted on the plate 17 by virtue of bearing blocks 19. The plate 17 is slidably mounted on the second stand 18 by virtue of guide blocks 20 that are fastened to the underside of the plate 17. The guide blocks 20 are slidably mounted on guide rails 21 arranged towards each opposing end of the second axle 16 and extending perpendicular to the second axle 16. An engagement drive 22 _vis mounted on the second stand 18 and connected to the plate 17 for displacing the plate 17 along the guide rails 21, thereby driving the second wheel 13 toward the first wheel 2. Referring particularly to Figures 2 and 7, the engagement drive 22 is mounted on the second stand 18 by virtue of a mounting bracket 23 and connected to the plate 17 by a drive bracket 24. Rotation of the handle 25 of the engagement drive rotates a worm gear 26 coupled to the handle 25 by way of a shaft 27. Rotation of the worm gear 26 draws the worm gear 26 and shaft 27 along a rack 28 fixed in relation to the bracket 23, thereby displacing the drive bracket 24, that is longitudinally fixed in relation to shaft 27. Displacement of the drive bracket 24 accordingly displaces the plate 17, second axle 16 and second wheel 13. Rather than having the second axle 16 displaceable and the first axle 5 fixed, the first axle could be arranged to be displaceable with the second axle 16 fixed, or alternatively both first and second axles 5, 16 could be arranged to be displaceable by any suitable means. Similarly, the drive motor 8 could be arranged to drive the second axle 16 rather than the first axle 5. The second wheel 13 has a circumferential peripheral surface 29 adapted to receive a layer of road surface material 30, as depicted in Figures 2 and 8. Annular flanges 31, 32 are provided on each side of the circumferential peripheral surface 29 and extend radially beyond the peripheral surface 29 so as to assist in retaining the layer of road surface material 30 on the peripheral surface 29. A series of pins 33 project generally radially from the peripheral surface 29 to again assist in retaining the layer of road surface material 30. Here the pins 33 have hooked ends to further assist in retaining the layer of road surface material 30. The layer of road surface material 30 is formulated in accordance with that of the specific road surface material which is desired to be tested. The road surface material 30 is laid onto the second wheel peripheral surface 29, and compacted if necessary, consistent with the manner in which a layer of road surface material would typically be applied to a road substrate. The layer of road surface material 30 would typically be applied with the second wheel 13 removed from the second stand 18. To conduct testing of the tyre 12 and/or road surface material 30, the second wheel 13 is displaced toward the first wheel 2 utilising the engagement drive 22 until the tyre 12 engages the road surface material 30. Load transducers (typically strain gauges) may be utilised as desired so as to enable a desired engagement load to be applied between the tyre 12 and the road surface material 30 by advancing the second wheel 13 utilising the engagement drive 22 until the desired engagement load is achieved. The first wheel 2 is driven by the drive motor 8. Engagement of the tyre 12 mounted on the first wheel 2 with the road surface material 30 mounted on the second wheel 13 will result in the second wheel 13 being rotated about the second axis 14. Accordingly, the testing machine 1 simulates a wheel mounted tyre being driven over a road surface. Whilst a road surface might usually be generally flat, the tyre will typically only engage the road surface over a relatively short length and accordingly the curvature of the road surface material 30 applied to the second wheel 13 is not envisaged to create any significant adverse affect. If desired, however, the radius of the second wheel 13 can be increased as desired so as to reduce the curvature of the layer of road surface material 30. Further, to at least more accurately visually simulate a tyre running on a road surface, the first axis 3 may be arranged vertically above the second axis 14, such that the tyre 12 runs on top of the road surface material 30, rather than beside it as in the depicted arrangement. The drive motor 8 may commence driving of the first wheel 2 either before or after the road surface material 30 has been engaged with the tyre 12. The output of the drive motor 8 may be adjusted as desired so as to vary the speed of rotation of the first wheel 2, thereby simulating varying speeds of a wheel mounted tyre being driven across a road surface. Speed transducers may be utilised as desired to enable control and recording of the wheel speed. The testing machine 1 is particularly suitable for testing the noise generated by the interaction of various tyre and road surface configurations. When conducting such acoustical testing, one or more microphones 34 may be mounted nearby the region of engagement between the tyre 12 and road surface material 30, as depicted in Figure 1. As the bulk of the noise generated by the interaction of a tyre and road surface is generated near the forward edge of the region of engagement, a single microphone located nearby this point will be sufficient for some applications, however if desired an array of microphones may be arranged in any suitable configuration meeting the requirements of the applicable national standards. The microphone(s) 34, speed transducers and load transducers will all be coupled to a central processing unit that records the noise level results against speed and tyre load. Utilising the test machine 1, extraneous noise sources such as are experienced with current motor vehicle and open road based testing procedures are at least substantially eliminated. To further reduce the effect of any extraneous noise sources, the drive motor 8 will typically be acoustically shielded. The testing machine 1 will also typically be housed within a wire cage for worker safety reasons, particularly in case of any possible tyre blowout. When the testing machine 1 is being used to assess the noise characteristics of various road surfaces, a standard tyre will be utilised during all tests so as to serve as a common reference base. Alternatively, when the noise characteristics of various tyres are to be tested, a standard road surface material will be utilised, so as again to provide a common reference base for which various tyres can be assessed. Apart from acoustical testing of tyres and/or road surfaces, the testing machine 1 may be utilised to conduct various other tests of tyres and or road surfaces, including wear testing by driving the first wheel 2 over an extended period of time. With testing procedures being carried out in an isolated environment, the effects of environmental change on various tests can be conducted by introducing different enviromnent conditions (such as temperature, humidity, precipitation) within the test environment. The person skilled in the art will appreciate further possible test procedures that may be carried out utilising the testing machine, and appropriate modifications to the testing machine to allow for such further test procedures to be carried out.

Claims

Claims: 1. An apparatus for testing a tyre and/or road surface, said apparatus comprising: a first wheel mounted for rotation about a first axis and being adapted to receive a tyre; a second wheel mounted for rotation about a second axis, said second axis being substantially parallel to said first axis, said second wheel having a circumferential peripheral surface adapted to receive a layer of road surface material; and a drive motor for rotatably driving one of said first and second wheels; wherein said second axis is displaceable relative to said first axis for engaging the tyre with the road surface material in use. 2. The apparatus of claim 1 further comprising the tyre mounted on said first wheel. 3. The apparatus of claim 1 further comprising the layer of road surface material mounted on said second wheel circumferential peripheral surface. 4. The apparatus of claim 1 further comprising a first axle rotatable about said first axis and a first wheel mount fixed in relation to said first axle, said first wheel being mounted on said first wheel mount. 5. The apparatus of claim 1 further comprising a second axle rotatable about said second axis and a second wheel mount fixed in relation to said second axle, said second wheel being mounted on said second wheel mount. 6. The apparatus of claim 1 wherein said drive motor is arranged to rotatably drive said first wheel. 7. The apparatus of claim 1 wherein said first axis is fixed and said second axis is displaceable. 8. The apparatus of claim 1 further comprising an engagement drive for displacing said second axis relative to said first axis for engaging the tyre with the road surface in use. 9. The apparatus of claim 1 further comprising one or more microphones located adjacent an interface between the tyre and the road surface material when the tyre is engaged with the road surface material. 10. The apparatus of claim 1 wherein said drive motor is acoustically shielded. 11. A method of testing a tyre and or road surface comprising the steps of: mounting a tyre on a first wheel, said first wheel being rotatable about a first axis; laying a road surface material on a circumferential peripheral surface of a second wheel, said second wheel being rotatable about a second axis; displacing said second axis with respect to said first axis to thereby engage said tyre and said road surface material; and rotatably driving one of said first and second wheels. 12. The method of claim 11, further comprising the step of measuring noise generated by the interaction of said tyre and said road surface.