METHOD FOR POSITIONING AT LEAST ONE WHEEL HOLDER OF A VEHICLE TEST BENCH

Abstract

The present invention relates to a method of positioning at least one wheel support of a vehicle dynamometer in relation to the position of a wheel in the longitudinal direction of a vehicle standing on the vehicle dynamometer. The wheel support is positioned using a drive unit for adjusting the position of the wheel support. The positioning takes place with a vehicle located on the vehicle dynamometer, wherein the vehicle is held in place during the positioning at least in relation to its longitudinal direction. The positioning of the wheel support takes place as a function of a variable that represents a three to be applied by the drive unit and/or a torque to be applied by the drive unit and/or the power consumption of the drive unit and/or the work done by the drive unit when the wheel support is moved along a defined distance when a specific movement profile of the wheel support is achieved during movement in a direction corresponding to the longitudinal direction of a vehicle standing on the vehicle dynamometer.

Claims

1. A method of positioning at least one wheel support (1; 401) of a vehicle dynamometer in relation to the position of a wheel (4; 404) in the longitudinal direction of a vehicle standing on the vehicle dynamometer, wherein the wheel support (1; 401) has a single roller (402) or a twin roller (2, 3), wherein the wheel support (1; 401) is positioned using a drive unit for adjusting (5; 405) the position of the wheel support (1; 401), characterized in that the positioning takes place with a vehicle located on the vehicle dynamometer, wherein the vehicle is held in place during the positioning, at least in relation to its longitudinal direction, wherein the positioning of the wheel support (1; 401) takes place as a function of a variable that represents a force to be applied by the drive unit and/or a torque to be applied by the drive unit and/or the power consumption of the drive unit and/or the work done by the drive unit when the wheel support (1; 401) is moved along a defined distance when a specific movement profile of the wheel support (1; 401) is achieved during a movement (5; 405) in a direction corresponding to the longitudinal direction of a vehicle standing on the vehicle dynamometer.

2. The method according to claim 1, characterized in that the wheel support (1) has a twin roller (2, 3) and in that the position of the wheel support (1) is adjusted as a function of an identified minimum of the variable during a movement of the wheel support (1) in a range in which a wheel (4) of the vehicle is located between the two rollers (2, 3) of the wheel support (1).

3. The method according to claim 1, characterized in that the wheel support (401) has a single roller (402) and in that the position of the wheel support (401) is adjusted as a function of an identified maximum of the variable during a movement of the wheel support (401) in a range in which a wheel (404) of the vehicle stands on the single roller (402).

4. The method according to one of claims 1 to 3, characterized in that the drive unit is an electric motor and in that the variable is the power consumption of the electric motor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In the drawings, the conditions during the movement of the wheel support in the longitudinal direction are illustrated again for explanatory purposes. The figures show the following:

[0035] FIG. 1: a schematic diagram of a wheel support as a twin roller with a vehicle wheel standing on one of the two rollers,

[0036] FIG. 2: a schematic diagram of the wheel support as a twin roller according to FIG. 1 with a vehicle wheel standing on the other of the two rollers,

[0037] FIG. 3: a force profile of a drive unit for moving the wheel support from the position of FIG. 1 to the position of FIG. 2,

[0038] FIG. 4: a schematic diagram of a wheel support as a single roller with a vehicle wheel standing on one side of the single roller,

[0039] FIG. 5: a schematic diagram of the wheel support as a single roller according to FIG. 4 with a vehicle wheel standing on the other side of the single roller,

[0040] FIG. 6: a force profile of a drive unit for moving the wheel support from the position of FIG. 4 to the position of FIG. 5.

DETAILED DESCRIPTION

[0041] FIG. 1 shows a schematic diagram of a wheel support 1 as a twin roller 2, 3 with a vehicle wheel 4 standing on one of the two rollers 3.

[0042] The conditions for the movement of the wheel support 1 relative to the vehicle wheel 4 are explained with the aid of a movement of the wheel support 1 in the direction of the arrow 5 relative to the position of the vehicle wheel 4.

[0043] During this movement the wheel initially sinks down between the two rollers 2, 3 of the wheel support 1. During the movement, the force needed to move the wheel support 1 in the direction of the arrow 5 decreases. Since the vehicle wheel 4 does not fall in a linear fashion compared to the movement of the wheel support in the direction of the arrow 5, the force curve is likewise non-linear.

[0044] When the wheel support 1 has been moved sufficiently far that the vehicle wheel 4 is located precisely between the two rollers 2, 3 in the longitudinal direction, the vehicle wheel 4 is at its lowest.

[0045] During a further movement of the wheel support in the direction of the arrow 5 relative to the vehicle wheel 4, the vehicle wheel 4 is raised again. As a result thereof, the force needed to drive the wheel support 1 increases again, until the vehicle wheel 4 stands on the upper apex of the roller 2.

[0046] FIG. 2 shows a schematic diagram of the wheel support 1 as a twin roller 2, 3 according to FIG. 1 with a vehicle wheel standing on the other of the two rollers 2. The wheel support 1 has accordingly been moved further in the direction of the arrow 5.

[0047] FIG. 3 shows the force profile of a drive unit for moving the wheel support 1 from the position of FIG. 1 to the position of FIG. 2.

[0048] It can be seen that the three initially falls and, when the lowest point of the vehicle wheel 4 is passed, it rises sharply. The range of interest in the force profile during the movement of the wheel support here (transition between the positions: “vehicle wheel 4 stands on the upper apex of the roller 3” and “vehicle wheel 4 stands on the upper apex of the roller 2”) is marked on the curve of the force profile such that this range of interest lies between the two marks on the curve profile of FIG. 3.

[0049] FIG. 4 shows a schematic diagram of a wheel support 401 as a single roller 402 with a vehicle wheel 404 in contact with the single roller 402 on the “right-hand” side (in the illustration of FIG. 4).

[0050] The conditions of the movement of the wheel support 401 relative to the vehicle wheel 404 are explained with the aid of a movement of the wheel support 401 in the direction of the arrow 405 relative to the position of the vehicle wheel 404.

[0051] During this movement the wheel 404 is initially raised until the wheel stands on the upper apex of the single roller 402. During the movement, the force needed to move the wheel support 401 in the direction of the arrow 405 increases. Since the vehicle wheel 404 does not rise in a linear fashion compared to the movement of the wheel support 401 in the direction of the arrow 405, the force curve is likewise non-linear.

[0052] When the wheel support 401 has been moved so far that the vehicle wheel 404 stands on the apex of the single roller 402, the vehicle wheel 404 is at its highest.

[0053] During a further movement of the wheel support 401 in the direction of the arrow 405 relative to the vehicle wheel 404, the vehicle wheel 404 sinks down again. As a result of this, the force needed to drive the wheel support 401 decreases.

[0054] FIG. 5 shows a schematic diagram of the wheel support 401 as a single roller 402 with a vehicle wheel 404 in contact with the single roller 402 on the “left-hand” side (in the illustration of FIG. 5). The wheel support 401 has accordingly been moved further in the direction of the arrow 5, based on the illustration of FIG. 4.

[0055] FIG. 6 shows the force profile of a drive unit for moving the wheel support 401 from the position of FIG. 4 to the position of FIG. 5.

[0056] It can be seen that the force initially falls to an inflection point in the curve of the force profile and then falls further. The inflection point here corresponds to the position of the wheel support 401 at which the vehicle wheel 404 stands on the apex of the single roller 402.

[0057] Since in the case of a single roller the vehicle wheel changes its position in a vertical direction less in the region immediately surrounding the apex during a displacement of the single roller relative to the vehicle wheel than at a greater distance from this apex, it can be useful in the case of a single roller to determine the position at which the vehicle wheel 404 stands on the apex of the single roller 402 by evaluating a larger section of the force profile.

[0058] The curve profile of FIG. 6 can be explained by the fact that, during a movement of the vehicle wheel 404 towards the apex, when the wheel support is displaced by a specific distance the vehicle wheel must be raised by a larger amount at a greater distance from the apex than at a closer distance during a movement of the vehicle wheel towards the apex. During a movement away from the apex, the same applies to the lowering of the vehicle wheel.