DE-102024210815-A1 - Wind tunnel scale

DE102024210815A1DE 102024210815 A1DE102024210815 A1DE 102024210815A1DE-102024210815-A1

Abstract

Wind tunnel balance for a vehicle test rig with at least one fastening device (21) designed to hold a vehicle (1) placed on the wind tunnel balance in a predetermined position; at least one measuring device (7) for recording measured values, in particular the forces between the fastening device (21) and a support; wherein, to correct dynamic effects of the wind tunnel balance on the at least one measured value of the measuring device (7), at least one acceleration sensor (11) coupled to the fastening device (21) is provided.

Inventors

Anton Knestel
Jürgen Küchle

Assignees

AIP GMBH & CO. KG

Dates

Publication Date: 20260513
Application Date: 20241111

Claims (20)

Wind tunnel balance for a vehicle test rig with at least one fastening device (21) designed to hold a vehicle (1) placed on the wind tunnel balance in a predetermined position; at least one measuring device (7) for recording measured values, in particular the forces between the fastening device (21) and a support; wherein, to correct dynamic effects of the wind tunnel balance on the at least one measured value of the measuring device (7), at least one acceleration sensor (11) coupled to the fastening device (21) is provided.
Wind tunnel scale for a vehicle test rig comprising: a weighing frame (6) supported by one or more measuring means (7; 9; 10) in the Y-direction and/or in the X-direction and/or Z-direction; at least one sill support (5) configured to hold a vehicle (1) placed on the wind tunnel scale in a predetermined position, in particular relative to the weighing frame (6); wherein the measuring means (7; 9; 10) are configured to detect measured values, in particular the forces between the weighing frame (6) and supports of the weighing frame (6); and in which, to correct dynamic effects of the wind tunnel scale on the at least one measured value of the measuring means (7; 9; 10), at least one acceleration sensor (11) coupled to the sill support (5) is provided.
Wind tunnel scale for a vehicle test bench according to Claim 1 or 2 , wherein the acceleration sensor (11) is fixed directly to the sill support (5) or fastening device (21) and wherein the acceleration sensor (11) is in particular configured to detect at least accelerations of the mass of the vehicle (1).
Wind tunnel scale for a vehicle test bench according to Claim 2 or 3 , wherein at least one additional acceleration sensor (11a) is provided on the weighing frame (6) to detect the accelerations of the mass of the weighing frame (6).
Wind tunnel scale for a vehicle test bench according to Claim 1 or 2 , wherein the accelerometer (11) is configured to detect accelerations in one or more of the directions X, Y and Z and/or one of the accelerometers (11) is provided for each direction to detect accelerations in multiple directions from X, Y and Z.
Wind tunnel scale for a vehicle test bench according to Claim 1 , wherein the measuring means (7) comprise at least one measuring means, in particular a force sensor, for measurement in the X direction and/or at least one, preferably four, measuring means (10), in particular force sensors, for measurement in the Z direction.
Wind tunnel scale for a vehicle test rig according to at least one of the preceding claims, further comprising: at least one belt unit (17) comprising at least one belt unit frame (15) on which at least one treadmill (13) is provided for arranging the vehicle (1) on which it is wound around at least two rollers (19).
Wind tunnel scale for a vehicle test bench according to Claim 7 , wherein at least one measuring device coupled to the belt unit (17), in particular force measuring device, is provided for recording measured values in the Z direction.
Wind tunnel scale for a vehicle test stand according to one of the preceding claims, wherein the weighing frame (6) is mounted relatively movably, and in which the at least one sill support (5) is coupled to the weighing frame (6), in particular attached to it, and in which the measuring means (7; 9; 10) are provided such that measured values, in particular forces, between the support and the weighing frame (6) can be detected with them.
Wind tunnel scale according to at least one of the preceding claims, wherein at least two of the measuring means (7; 9; 10) are coupled to the weighing frame (6) at different locations with respect to the X-direction and are configured to acquire measured values in the Y-direction and/or Z-direction and/or wherein at least two of the measuring means (7; 9; 10) are coupled to the weighing frame (6) at different locations with respect to the Z-direction and are configured to acquire measured values in the X-direction and/or Y-direction.
Wind tunnel scale according to at least one of the preceding claims, wherein at least two of the acceleration sensors (11) are coupled to the weighing frame (6) at different locations with respect to the X-direction and are configured to detect acceleration values of the weighing frame (6) in the Z-direction and/or wherein at least two of the acceleration sensors (11) are coupled to the weighing frame (6) at different locations with respect to the Z-direction and are configured to detect acceleration values of the weighing frame (6) in the X ... The angular sensors (11) are coupled to the weighing frame (6) at different points with respect to the Y-direction and are configured to detect acceleration values of the weighing frame (6) in the X-direction.
Wind tunnel balance according to at least one of the preceding claims, wherein one or more of the measuring means (7; 9; 10) are formed as strain gauges, in particular strain gauge force transducers, or piezoelectric force transducers; and/or the weighing frame (6) is supported in the X-direction and/or Y-direction essentially solely by the measuring means (7; 9; 10).
Wind tunnel balance according to at least one of the preceding claims, wherein at least one of the measuring means (7; 9; 10) can be bridged by means of a switchable, in particular piezoelectric, force transducer arranged in parallel thereto.
Wind tunnel balance according to at least one of the preceding claims, wherein the wind tunnel balance is configured to correct at least one value detected by means of the measuring means (7; 9; 10) with at least one acceleration value measured by the accelerometer (11; 11a) and the accelerated mass.
Wind tunnel balance according to at least one of the preceding claims, wherein the wind tunnel balance is configured to add the inverse transfer behavior resulting from the mass of the weighing frame (6) and the spring stiffness of its bearing in order to correct the measured value of the measuring means (7; 9; 10).
Wind tunnel balance according to at least one of the preceding claims, wherein a high-pass filter (51) is provided for correcting the output value of the acceleration sensor (11; 11a) of offset values and wherein an integrator (52) is provided for integrating the acceleration, in particular the corrected output value, for determining a velocity.
Method for determining the dynamic behavior of a system consisting of a vehicle (1) and a wind tunnel scale, comprising at least the following method step: Excitation of a vehicle (1) arranged on the wind tunnel scale by means of a oscillator, in particular an electromechanical oscillator, with different frequencies and determination of excitation frequency-dependent motion values of the vehicle (1) and a weighing frame (6) of the wind tunnel scale in one or more of the directions X, Y and Z by means of acceleration sensors (11).
Procedure according to Claim 17 , whereby the dynamic transfer behavior of the system vehicle (1) wind tunnel scale is modeled using the determined measurement results of the movement over the frequency.
Method for determining the vehicle masses involved in a vehicle using a wind tunnel balance, comprising the following steps: (a) Positioning the vehicle on the wind tunnel balance; (b) Supporting the vehicle by means of a fastening device (21) against a support bearing (3) of the wind tunnel balance; (c) Recording measured values, in particular forces, between the vehicle (1) and the support bearing (3) using measuring instruments (10) and simultaneously recording at least one acceleration value using at least one acceleration sensor (11, 11a) coupled to the vehicle (1) and/or the fastening device (21); (d) Correcting at least one of the measured values of the measuring instruments (7) using at least one of the acceleration values.
Method for determining the vehicle masses involved in a vehicle using a wind tunnel scale, comprising the following steps: (a) Positioning the vehicle on the wind tunnel scale; (b) Supporting the vehicle by means of at least one sill support (5) against a weighing frame (6) of the wind tunnel scale; (c) Recording measured values, in particular forces, by means of measuring instruments (10) between the weighing frame (6) and at least one support bearing (3) in at least one direction and simultaneously recording at least one acceleration value by means of at least one acceleration sensor coupled to the vehicle and/or the sill support (5); (d) Correcting at least one of the measured values of the measuring instruments (10) by means of at least one of the acceleration values.

Description

The present invention relates to a wind tunnel balance that enables highly accurate measurements; in particular, dynamic forces can be taken into account using the wind tunnel balance according to the invention. Various designs of wind tunnel balances are known in the prior art, which serve to measure the aerodynamic forces and moments that a vehicle experiences during a wind tunnel test. To closely approximate the real-world conditions of the airflow around a vehicle during road travel, this situation is simulated, for example, in specially designed wind tunnels with one or more integrated treadmills ("rolling road"). The treadmills move beneath the vehicle at a speed roughly equivalent to the airflow speed towards the vehicle. Single-belt, three-belt, or five-belt systems are commonly used to measure the forces acting on a two-axle vehicle during aerodynamic tests in a wind tunnel. Single-belt systems feature a belt unit with a wide, continuous track that rotates on two rollers or drums. For aerodynamic tests, the vehicle is positioned with all wheels on this single track and fixed relative to it. In three-belt systems, the vehicle rests with the wheels of different axles arranged one behind the other on separate belts, while another belt runs between them as a center belt unit. In a five-belt test rig configuration, a center belt unit and, to the side, a belt unit are positioned under each of the vehicle's four wheels. The belts are supported by so-called weighing pads at the points where the vehicle's wheels rest on them. Sometimes, in state-of-the-art technology, the belts are held in place by a weighing frame. During the measurement, the car is held in position and prevented from rolling away by fastening devices, such as so-called sill supports. Forces are measured, for example, by introducing the forces at the weighing pads and the sill supports into a movable weighing frame, where they are recorded by suitable sensors and then evaluated by a computer. The sill supports and wheel supports are connected to the weighing frame, while the central track and other covers are not connected to the scale. The moving central track allows for the adjustment of equal airflow on and under the vehicle. This arrangement enables the measurement of all forces acting on the vehicle in the X, Y, and Z directions. The corresponding torques Mx, My, and Mz on the vehicle can also be calculated. In the EP 1 656 541 B1 A wind tunnel scale with a single-band dynamometer is shown. The vehicle is positively connected to a weighing frame by means of sill supports. In the DE 11 2009 000 488 B4 The vehicle is held in position by struts. The forces are measured using load cells. With state-of-the-art measuring devices, forces can be recorded statically over a long averaging period. The weighing frame, such as the one in the DE 10 2011085 640 A1 Furthermore, other parts of such a measurement setup also possess considerable mass. Due to the inertia and elasticity of force-transmitting components of the wind tunnel balance, oscillations can occur during dynamic measurements. The oscillating systems can exhibit their resonant frequency within the desired measurement range, thus at least distorting the dynamic measurement. Single-mass oscillators exhibit one resonant frequency, while multi-mass oscillators exhibit several. This behavior limits the measuring devices to quasi-static measurements. At the very least, their usable frequency range is severely restricted. The resonant frequency is determined by dividing the square root of the spring rates by the masses. The resonance amplification depends on the damping of the system. In largely undamped systems, it is not uncommon for the measured values to increase by a factor of 10 at resonance. Damping these oscillating systems is difficult in practice because, firstly, the measuring ranges are very small, and secondly, friction should be avoided, as it can negatively affect the accuracy of the measurement. It is therefore an object of the invention to provide a wind tunnel scale and a method for determining the vehicle masses involved in a vehicle with a wind tunnel scale, which provide improved measurement accuracy and in particular can better take dynamic forces into account during measurement. This problem is solved by a wind tunnel scale and a method for determining the vehicle masses involved in a vehicle using a wind tunnel scale, according to the independent claims. Preferred embodiments of the invention are specified in the dependent claims. According to one aspect of the present invention, a wind tunnel balance according to the invention for a vehicle test rig can have the following: at least one fastening device configured to hold a vehicle placed on the wind tunnel balance in a predetermined position; at least one measuring means for recording measured values, in particular the forces between the fastening device and a support; wherein, for correcting dynamic effects of the w