This application is a National Stage completion of PCT/EP2016/076897 filed Nov. 8, 2016, which claims priority from German patent application serial no. 10 2015 224 638.8 filed Dec. 8, 2015.
The invention relates to a wheel-force dynamometer.
From DE 102 60 000 B4 by the present applicant a wheel-force dynamometer for measuring tire forces is known, wherein a vehicle wheel is fixed onto a wheel axle which is mounted by roller bearings in a hollow shaft. The hollow shaft is mounted hydrostatically in a housing fixed to a frame and has a collar on which force sensors for the measurement of forces and torques are arranged. The forces acting on the wheel are thus transmitted via the wheel axle to the hollow shaft, which for its part “floats” in a frictionless manner by hydrostatic means in the housing. During the measurement of tire forces by a wheel-force dynamometer, measurement errors can occur, which are determined by the design of the measuring device and its vibration behavior.
An objective of the invention is to propose an improved wheel-force dynamometer.
According to the invention, this objective is achieved by the wheel-force dynamometer according to the independent claims. Advantageous design features emerge from the subordinate claims.
The invention relates to a wheel-force dynamometer for the measurement by means of force sensors of forces and torques acting on a vehicle tire and a vehicle wheel, wherein the vehicle wheel is mounted and can rotate on a wheel axle. The wheel-force dynamometer according to the invention is characterized in that the wheel axle is in the form of a compact rotor which is mounted axially fixed and able to rotate in the circumferential direction in a rigid and positionally fixed housing. Since the wheel axle is no longer made solid and mounted inside a hollow shaft—as in the prior art—but, according to the invention, is in the form of a compact rotor held in a housing, by virtue of the larger diameter and annular cross-section of the housing, a maximum modulus of resistance and thus high rigidity is achieved. Moreover the mass of the wheel axle is reduced. Furthermore a housing that is rigid and does not rotate is provided, which accommodates the compact rotor. The positionally fixed housing in combination with the compact rotor provides an exceptionally rigid wheel mounting which deforms very little under the action of the tire forces that occur during the measurements. The invention is based on the recognition that a reason for measurement errors relates to a relatively low natural frequency of the measurement device compared with the measurement frequencies which are desirable in the context of a so-termed High Speed Uniformity (HSU) measurement. Thanks to the compact rotor and rigid housing that constitute the wheel mounting according to the invention, high rigidity and hence a relatively high natural frequency of the wheel-force dynamometer are obtained. The occurrence of resonances at the measurement frequencies can therefore be avoided, since the measurement frequencies are lower than the natural frequencies of the wheel mounting. This results in optimized transfer functions, which show smaller amplitude increases and smaller phase shifts.
According to a preferred embodiment of the invention, it is provided that the housing comprises a housing body and a housing lid. Thus, the compact rotor can be clamped firmly between the housing body and the housing lid. This results in comparatively higher rigidity with only low mass, which in turn results in higher natural frequencies. Furthermore, the housing can then be opened so as to position the compact rotor in the housing or remove it therefrom. In particular, this simplifies maintenance operations. The housing lid can be fixed onto the housing body for example by means of screw connections.
According to a further preferred embodiment of the invention, it is provided that the compact rotor has an external collar. Advantageously, the external collar provides a suitable point of engagement for clamping or mounting the compact rotor in the housing in an axially fixed, yet circumferentially rotatable manner. At the same time this contributes toward increasing the rigidity.
In a further preferred embodiment of the invention, it is provided that the compact rotor comprises a rotor head and a rotor ring, wherein the rotor head and the rotor ring each have a radial circumference variation such that in the area of an axial middle of the rotor they taper or thicken in a conical manner. The oblique flanks of this radial circumference variation provide an alternative point of engagement for clamping or mounting the compact rotor in the housing in an axially fixed, yet circumferentially rotatable manner.
According to a particularly preferred embodiment of the invention, it is provided that the housing lid has an opening through which a rotor head of the rotor is passed. In that way the vehicle tire can be attached to the rotor head while the rotor is held and can rotate in the housing.
In another preferred embodiment of the invention, it is provided that the housing body is supported on a positionally fixed supporting structure. This realizes the concept of a cantilevered beam, with high rigidity and a high natural frequency.
According to a further preferred embodiment of the invention, it is provided that the force sensors are arranged between the housing body and the supporting structure. Forces or torques produced by rotation of the vehicle tire or vehicle wheel spread into the housing. By way of the housing body these forces or torques are transmitted to and detected by the force sensors. In this context a plurality of in part different force sensors can be provided for measuring the tire forces.
In a particularly preferred embodiment of the invention, it is provided that the wheel-force dynamometer also comprises slide bearings arranged between the rotor and the housing. These ensure that the rotor can rotate relative to the housing with very little friction.
According to a quite especially preferred embodiment of the invention it is provided that a first slide bearing is in the form of a radial bearing and a second and a third slide bearing are in each case in the form of axial bearings. This increases the rigidity of the bearing design while at the same time ensuring low-friction rotation of the rotor relative to the housing.
In an also very particularly preferred embodiment of the invention, it is provided that a first and a second slide bearing are made in the form of conical bearings. This too increases the rigidity of the bearing system while at the same time ensures low-friction rotation of the rotor relative to the housing, and at the same time a minimum number of slide bearings are needed, namely just two slide bearings.
According to an also particularly preferred embodiment of the invention, it is provided that the slide bearings are in the form of hydrostatic slide bearings. In hydrostatic bearings the necessary lubricant film is provided by an additional lubricant oil pump which delivers the lubrication oil under pressure into the lubrication gap. For a hydrostatic slide bearing this has the advantage that already on starting, i.e. at low rotational speeds, minimal friction occurs. A further advantage is that compared with conventional roller bearings a hydrostatic slide bearing has higher rigidity even at very low excitation frequencies. At higher frequencies, namely those relevant for the measurement of high speed uniformity (HSU), the rigidity is very much greater than with roller bearings. Accordingly the hydrostatic slide bearings also contribute substantially toward making the most of the rigidity potential of the wheel mounting, i.e. increasing the natural frequency of the measurement device.
In a further particularly preferred embodiment of the invention, it is provided that the second and the third slide bearings are arranged on opposite axial end faces of the collar. This too has been found particularly advantageous in relation to the rigidity of the mounting.
According to another preferred embodiment of the invention, it is provided that the rotor head of the rotor can be connected in a rotationally fixed manner to the vehicle wheel by means of wheel flange adapters. This provides a suitable option for the rigid and rotationally fixed connection of the vehicle wheel to be tested to the wheel-force dynamometer. In this case the wheel flange adapters are designed such that they enable wheel rims with different rim dimensions to be attached to the wheel-force dynamometer.
In a further preferred embodiment of the invention, it is provided that the housing body has a stud that engages in the rotor at least in the area of the collar. On the one hand this additionally supports the mounting of the rotor in the housing, and on the other hand it further increases the rigidity of the wheel-force dynamometer.
In another preferred embodiment of the invention, it is provided that a centering ring is arranged on the rotor head of the rotor. The centering ring ensures that the vehicle tire or vehicle wheel is centered relative to the rotor and the housing.
Example embodiments of the invention are illustrated in the drawings and are described in greater detail below, so that further features and/or advantages can emerge from the description and/or the drawings, which show:
The mounting of the vehicle wheel 2 on the positionally fixed supporting structure 7 is designed as a rigid assembly so that the wheel-force dynamometer 1 has a as high as possible natural frequency. Accordingly the measurement frequencies at which the forces and torques are determined in a HSU measurement are substantially lower than the natural frequency of the wheel-force dynamometer 1. Thus, resonances between the natural frequency of the wheel-force dynamometer 1 and the measurement frequencies can be largely avoided, so that resonance-related measurement errors such as amplitude increases or phase shifts are minimized.
For a measurement the vehicle wheel 2 rolls on a real or simulated road (not shown in
The example embodiment of
The example embodiment of
Number | Date | Country | Kind |
---|---|---|---|
10 2015 224 638 | Dec 2015 | DE | national |
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/EP2016/076897 | 11/8/2016 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2017/097514 | 6/15/2017 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
3948095 | Burgett | Apr 1976 | A |
4499768 | Madden | Feb 1985 | A |
4555956 | Reich | Dec 1985 | A |
4726690 | Thelen | Feb 1988 | A |
4753110 | Burchett et al. | Jun 1988 | A |
4969355 | Doi | Nov 1990 | A |
5060513 | Rothamel | Oct 1991 | A |
5063773 | Fujimori et al. | Nov 1991 | A |
5689069 | Corghi | Nov 1997 | A |
6430992 | Goebel | Aug 2002 | B1 |
20020124650 | Matsumoto | Sep 2002 | A1 |
20030213301 | Buzzi | Nov 2003 | A1 |
20040003661 | Rothamel | Jan 2004 | A1 |
20120240677 | Sotgiu | Sep 2012 | A1 |
20130008249 | Sotgiu | Jan 2013 | A1 |
20160333888 | Miyahara | Nov 2016 | A1 |
20180372568 | Eisenbeiss | Dec 2018 | A1 |
Number | Date | Country |
---|---|---|
500 480 | Dec 1970 | CH |
1 201 581 | Sep 1965 | DE |
1 281 713 | Oct 1968 | DE |
36 12 599 | Oct 1987 | DE |
690 23 313 | Mar 1996 | DE |
198 44 975 | Mar 2000 | DE |
100 04 419 | Dec 2000 | DE |
100 44 291 | Sep 2001 | DE |
102 60 000 | Jul 2004 | DE |
10 2008 034 484 | Jan 2010 | DE |
0 192 789 | Sep 1986 | EP |
0 735 356 | Oct 1996 | EP |
1 239 275 | Sep 2002 | EP |
2 187 193 | May 2010 | EP |
2 602 602 | Jun 2013 | EP |
2015146735 | Oct 2015 | WO |
Entry |
---|
German Search Report Corresponding to 10 2015 224 636.1 dated Oct. 7, 2016. |
German Search Report Corresponding to 10 2015 224 638.8 dated Oct. 17, 2016. |
International Search Report Corresponding to PCT/EP2016/076898 dated Feb. 6, 2017. |
International Search Report Corresponding to PCT/EP2016/076897 dated Feb. 1, 2017. |
Written Opinion Corresponding to PCT/EP2016/076898 dated Feb. 6, 2017. |
Written Opinion Corresponding to PCT/EP2016/076897 dated Feb. 1, 2017. |
Number | Date | Country | |
---|---|---|---|
20190056283 A1 | Feb 2019 | US |