DE10053381C1 - Measuring device for vehicle testing provided by fifth wheel with cardan linkage and damping element providing road contact pressure dependent on pivot angle - Google Patents

Abstract

The testing device, mounted at the rear or side of a vehicle being tested, has a fifth running wheel (1), a rotation sensor (2), a fork (3), a cardan linkage (4,5,6) and a damping element (11) with a resetting force. The upper end of one orthogonal axis (Z) of the cardan linkage extends at an angle of between 10 and 60 degrees to the perpendicular to the road surface in opposition to the travel direction.

Description

Measuring wheels for determining vehicle dynamics parameters have been in use for decades Automotive industry known. An impeller with a known scope, which is in a fork is mounted behind or next to the test vehicle. The wheel will pulled like a single-axle trailer, which also gives the term drag wheel is common. Often these constructions are also called Peiseler-Rad or 5. Rad (English: Fifth Wheel). The rotary movement of the wheel is visual or magnetic sensors converted into a pulse train, or a coupled one Tachogenerator generates an output voltage proportional to the speed. Since that Towing wheel tends to jump when driving fast on uneven roads a spring construction or a brake cylinder in addition to its own weight Pressure force generated in the direction of the road.

The embodiment of a measuring wheel for the purpose mentioned is e.g. B. known from patent publication JP-A2 5-52710 (A). The measuring device, consisting of 2 coupled wheels, by a shock absorber and gas springs on the Lane kept. The special linkage is designed so that parts of it are always be guided perpendicular to the road and thus small momentary measurement errors, caused by pitching movements of the vehicle or bumps, automatically be balanced.

Thanks to the robust construction of the measuring wheel, it can also be used on poor road surfaces achieve a sufficient lifespan, however, the constructions mentioned at high risk if the test vehicle is reversed or the vehicle flings. In these situations, the measuring wheel breaks to the left at full pressure or right out. Strong lateral forces act on the impeller. With further Swiveling the measuring wheel is pressed on or under the vehicle, which is usually next to the damage to the measuring vehicle leads to total damage to the wheel and fork. The above-mentioned version according to JP-A2 5-52710 (A) is also for reverse Maneuvering unsuitable.

It has therefore been proposed several times to install a lifting device, which when driving backwards counter the wheel by a servo motor or a hydraulic system the pressure force lifts off the floor. On the one hand, this solution is complex and expensive, on the other hand, if the test vehicle is suddenly spun, not fast enough to To prevent damage safely. The attitude of the Trigger point for the lifting device.  

Bypasses a special embodiment of a measuring wheel from Peiseler GmbH this problem by mounting the impeller in a frame so that it can turn freely when reversing. This principle is also rotatable Furniture castors known. A similar design is also described in DE 196 46 011 A1 proposed for the yaw moment measurement of a vehicle. Because of uneven streets a precision measuring wheel needs a certain minimum size. Transferred to that The above swing principle is a relatively heavy and expensive construction of the Linkage required and a rotary transducer, which the electrical signals of the Forwarding speed sensor into the vehicle.

The described invention differs from the mentioned embodiments through the possibility of reversing with the test vehicle combined with further properties, such as simple construction, easy dismantling, robustness, low manufacturing costs and light weight. The security function at backward driving and skidding is achieved by pressing the Measuring wheel to the roadway is automatically dependent on the swivel angle, which means that when Lateral breaking out of the wheel no longer causes harmful transverse forces.

Fig. 1 shows an embodiment of the device in side view, consisting of impeller ( 1 ), rotation rate sensor ( 2 ), fork ( 3 ), horizontal joint ( 4 ), center piece ( 5 ), vertical joint ( 6 ), fastening piece ( 7 ), support rod ( 8 ), clamping screw ( 9 ), clamping piece ( 10 ) and damping element ( 11 ). The entirety of elements ( 1 ) to ( 11 ) is referred to below as the measuring wheel.

The measuring wheel is mounted via the mounting piece ( 7 ) at a rigid point behind the vehicle. The fastening piece ( 7 ) is designed in such a way that the axis Z of the vertical joint ( 6 ) is no longer perpendicular to the carriageway, but is inclined according to claim 1 by the angle α against the direction of travel. The vertical joint ( 6 ) enables the wheel to swivel at least by the angle β to both sides. ( Fig. 2)

In the simplest case, the damping element ( 11 ) can be a compression spring which is connected to a piston and installed in a sleeve. When the piston is inserted into the sleeve, a restoring force is created which is used to press the impeller onto the road. A hydraulic damping element that is configured in such a way that a constant restoring force that is independent of the rebound travel is also suitable.

Fig. 2 shows the impeller facing in the direction of travel, wherein the wheel additionally β in the positions shown in phantom = -70 ° and + 70 °. For reasons of clarity, the measuring wheel was shown in the two swiveled representations without a support rod, clamping piece and damping element.

For the sake of explanation, it is initially assumed that the damping element ( 11 ) is fully extended at the swivel angle β = 0 ° and that no restoring force acts. When the measuring wheel is swiveled manually, there is a rotary movement around the Z axis. The base point of the impeller describes an arc, the lowest point of which touches the road at the swivel angle β = 0 °. The more the wheel swings to the side with the fork, the greater the distance between the wheel and the road. (Dashed representation in Fig. 1 and Fig. 2)

In practical use, the damping element should be pretensioned by about half at the swivel angle β = 0 ° in order to be able to compensate for depressions and elevations in the roadway. In addition, the measuring wheel is at small amounts of β, such as. B. when cornering, kept constantly on the road. With larger deflections, e.g. B. when maneuvering or skidding, the damping element springs out to the limit, causing the pressure to be zero. The weight of the measuring wheel prevents it from constantly lifting off the ground. The swivel angle is limited by itself. Shear forces on the impeller ( 1 ) or the fork ( 3 ) are then only minimal and do no damage. When maneuvering backwards, the wheel is pushed in an inclined position over the ground. In this way, curbs can be overcome without damage.

In order to adjust the pre-tension of the damping element ( 11 ) comfortably, the clamping piece ( 10 ) can be loosened with a tensioning screw ( 9 ) and can be moved along the support rod ( 8 ). To mount the measuring wheel on the vehicle, the wheel ( 1 ) with the loosened clamping screw is swiveled to the left or right by about 70 ° so that it touches the ground in this position when the damping element is fully extended. Then the clamping piece ( 10 ) is fixed. In order not to have to estimate the optimal end point for the swivel angle, it is proposed to make a mark z. B. in the form of a color point on the center piece ( 5 ) and vertical joint ( 6 ). As soon as the vehicle starts to move straight ahead, the measuring wheel swivels to the angle β = 0 °, which causes the damping element ( 11 ) to compress and thus to be preloaded.

When the measuring wheel is mounted on the side of the vehicle, the invention can be conditional be used. When maneuvering backwards is due to targeted steering movements Start reversing to ensure that the wheel is on the vehicle opposite side pivots. For spin tests, the measuring wheel must be mounted on the rear become.

Claims (3)

1. Measuring device for vehicle tests consisting at least of the impeller ( 1 ), rotation sensor ( 2 ), fork ( 3 ), universal joint ( 4 , 5 , 6 ) and damping element with restoring force ( 11 ), mounted on the rear or the side of a test vehicle, characterized that the upper end of the Z axis of the universal joint ( 3 , 4 , 5 ) is inclined at an angle of 10 ° ≦ α ≦ 60 ° against the perpendicular to the road and against the direction of travel. 2. Measuring wheel according to claim 1, characterized in that a damping element with restoring force ( 11 ) bridges only the horizontal axis ( 4 ) of the universal joint and thus generates an additional contact force on the roadway to the weight of the measuring device, the additional contact force from the pivot angle β of the Depends on the measuring wheel in such a way that from a certain amount of the angle β the spring deflection of the damping element is exhausted and the additional contact pressure becomes zero. 3. Measuring wheel according to claim 1 and 2, characterized in that the upper mounting point for the damping element ( 11 ) is adjustable in height and thus the swivel angle at which the impeller ( 1 ) can be set before the test drive with the damping element fully extended in the unloaded state Loses contact with the ground and the additional contact pressure becomes zero.