Device and method for measuring and determining relevant parameters for the adjustment of the directions of travel of two steerable axles of a vehicle in relation to each other

Abstract

A device and method for determining parameters for adjusting the directions of travel of two steerable axles of a vehicle relative to each other is disclosed, wherein one measuring unit for measuring the individual toe angle of a vehicle wheel associated with the measuring unit is present on each side of the vehicle such that a first measuring unit is assigned to the wheel of the first of the steerable axles on the vehicle's left side and the second measuring unit is assigned to the wheel of the second of the steerable axles on the vehicle's right side, wherein the output signals from the measuring units are supplied to an evaluating unit, wherein the difference in the directions of travel of the two steerable axles is determined in the evaluating unit from the signals supplied from the measuring units and is provided as an output signal from the evaluating unit.

Claims

1. A device for measuring and determining relevant parameters for adjusting the directions of travel (A1, A2) of two steerable axles (A1, A2) of a vehicle relative to each other, whereby the adjustment of the direction of travel (A1, A2) of both steerable axles (A1, A2) is part of the adjustment of the parameters of the chassis alignment of the car and whereby the both steerable axles (A1, A2) are coupled mechanically, characterized in that only one measuring unit (1, 2) for measuring the individual toe angle (SpA1.sub.left, SpA2.sub.right) of a wheel associated with said measuring unit (1, 2) is present on each side of the vehicle in such a way that a first measuring unit (1) is assigned to the wheel of the first of B the steerable axles (A1, A2) on the vehicle's left hand side and that a second measuring unit (2) is assigned to the wheel of the second of the steerable axles (A2, A1) on the vehicle's right-hand side, the difference in the directions of travel (A1, A2) of the two steerable axles (A1, A2), or a parameter representing this difference , being determined in an evaluating unit (4) from the signals supplied from the measuring units (1, 2) and being provided as an output signal from the evaluating unit (4).

2. The device of claim 1, characterized in that the output signal from the evaluating unit (4) is supplied to a visual display unit (5) and displayed there.

3. The device according to claim 1, characterized in that the output signal from the evaluating unit (4) is supplied to an automatic adjusting unit (6) that interacts operatively with adjusting means (3) of the coupling of the directions of travel (A1, A2) of the two steerable axles (A1, A2) relative to each other, the automatic adjusting unit (6) being configured such that it acts on the adjusting means (3), as a function of the output signal from the evaluating unit (4), in such a way that the difference , or the parameter representing this difference , becomes zero.

4. The device according to claim 1, characterized in that the device also has a measuring system (204) for registering the position of the steering wheel (203) with a steering-wheel angle (), that, in addition, a measuring device (201) is provided for measuring the direction of travel (A1) of at least one of a vehicle's steerable axles (A1), that a corresponding signal is supplied from the measuring system (204) to an evaluating system (205), that the evaluating system (205) is also supplied, from the measuring device (201), with a signal representing the direction of travel (A1) of the at least one steerable axle (A1), that the evaluating system (205) is set up in such a way that, from the signals supplied to it from the measuring system (204) and the measuring device (201), taking the vehicle's steering-wheel gear ratio (Lb) into account, it determines and outputs a parameter (206) corresponding to an angle () by which, under the existing circumstances, the steering wheel (203) must be rotated relative to the steering column in order that, once the steering wheel (203) has been fully adjusted, the steering-wheel angle () is zero when the direction of travel (A1) of the steerable axle is zero.

5. A method for measuring and determining relevant parameters for adjusting the directions of travel (A1, A2) of two steerable axles (A1, A2) of a vehicle relative to each other, whereby the adjustment of the direction of travel (A1, A2) of both steerable axles (A1, A2) is part of the adjustment of the parameters of the chassis alignment of the car and whereby the both steerable axles (A1, A2) are coupled mechanically, characterized in that the directions of travel (A1, A2) of the two steerable axles (A1, A2) are adjusted relative to each other by means of only measuring unit (1, 2) per vehicle side by determining the difference () in the directions of travel (A1, A2) of the two steerable axles (A1, A2), or a parameter representing this difference (), from a measurement of the toe angle (SpA1.sub.left) of the left-hand wheel of a first axle (A1) and the measurement of the toe angle (SpA2.sub.right) of the right-hand wheel of the second axle (A2), mutual alignment of the directions of travel (A1, A2) of the two steerable axles (A1, A2) being performed in such a way that the difference (), or the parameter representing this difference (), becomes a smaller absolute value than a threshold value.

6. The method according to claim 5, characterized in that, in addition, the position of the steering wheel (203) with a steering-wheel angle () is registered, that the direction of travel (A1) of at least one of the vehicle's steerable axles (A1) is measured and that, from the position of the steering wheel (203), the measured direction of travel (A1) and the vehicle's steering-wheel gear ratio (Lb), a parameter (206) is determined and output that corresponds to an angle () by which, under the existing circumstances, the steering wheel (203) must be rotated relative to the steering column in order that, once the steering wheel (203) has been fully adjusted, the steering-wheel angle () is zero when the direction of travel (A1) of the steerable axle is zero.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) An embodiment of the invention is shown in the drawings,

(2) FIG. 1: shows a first device for aligning the directions of travel of two steerable axles and

(3) FIG. 2: shows a further device for performing steering-wheel adjustments.

DETAILED DESCRIPTION

(4) FIG. 1 shows two measuring units designated 1 and 2, each of which is assigned to one of the vehicle's wheels. It can be seen that these measuring units are assigned to wheels on different steerable axles A1 and A2, on different sides of the vehicle.

(5) Each of these measuring units 1 and 2 measures the toe angle of the wheel to which it is assigned.

(6) Reference numeral 3 designates an adjusting means for mutually aligning the directions of travel A1 and A2 of the two steerable axles A1 and A2.

(7) On condition that the total toe angles GSpA1 and GSpA2 of the axles A1 and A2 remain unchanged during the alignment, or that changes in the total toe angles are negligible, it follows from the above derivation that, from a measurement of the toe angle SpA1.sub.left and a measurement of the toe angle SpA2.sub.right, alignment can be effected in such a way that the value is a smaller absolute value than a threshold value.

(8) On the basis of this finding, the output signals from the measuring units 1 and 2 are supplied to an evaluating unit 4, which is configured in such a way that the value , or a parameter representing this value , is determined in the evaluating unit. To this end, the evaluating unit 4 has two input ports via which the output signals from the measuring units 1 and 2 are supplied to the evaluating unit 4. The evaluating unit 4 may be a computer that is appropriately programmed such thatbased on the above derivationthe value or a parameter representing this value is determined from these input variables.

(9) A visual display unit 5 is also visible, which displays the output signal from the evaluating unit 4, i.e. the value or a parameter representing this value.

(10) The visual display unit enables the value , or a parameter representing this value , to be displayed while the alignment work is being performed.

(11) During the alignment work, the directions of travel A1 and A2 of the two steerable axles A1 and A2 are mutually aligned. For as long as alignment work is being performed, therefore, the value or the parameter representing this value changes. Since this variable is displayed by the visual display unit 5, the mechanic can undertake the alignment work in such a way that the value , or the parameter representing this value , is a smaller absolute value than a threshold value and is, in the best of cases, zero.

(12) As an alternative to supplying the output signal from the evaluating unit 4 to a visual display unit 5, this output signal may also be supplied to an automatic adjusting unit 6. This automatic adjusting unit 6 may be configured such that, depending on the output signal supplied to it from the evaluating unit 4, it influences the adjusting means 3 in such a way that the value , or a parameter representing this value , becomes zero.

(13) In this case too (as shown in FIG. 1), the output signal from the evaluating unit 4 may be additionally supplied to a visual display unit 5. The automated alignment process can then also be monitored optically via the visual display unit 5.

(14) FIG. 2 shows the alternative configuration for the alignment 1 according to claims 5 and 6 of this invention. It shows a steerable vehicle axle with two wheels 202.

(15) A measuring device 201 for determining the direction of travel A1 of the steerable axle is assigned to these wheels 202. The measuring device 201 may correspond, for example, to the measuring units 1 and 2 shown in FIG. 1. The output signals from the measuring device 201 are supplied to an evaluating system 205.

(16) A steering wheel is also visible, to which a measuring unit 204 is assigned. This measuring unit 204 may be configured, for example, according to DE 10 2008 045 307 A1. The output signal(s) from the measuring unit 204 is/are also supplied to the evaluating system 205.

(17) In the evaluating system 205, a parameter corresponding to the steering-wheel misalignment is determined from the signals supplied to it and from the vehicle's steering-wheel gear ratio Lb.

(18) This parameter may be the steering-wheel misalignment direct (in amount and angular orientation) or it may be a parameter of the type alluded to in claim 5, for example, relating to the incremental adjustability of the steering wheel relative to the steering column.

(19) This parameter may be displayed as an output signal 206 on a visual display unit 207.

(20) It is also apparent from the context of what is shown in FIG. 2 that adjustment of the steering wheel with the procedure shown is independent of the procedure for adjusting vehicle parameters on the vehicle axle.