Vehicle alignment sensor system

Details Vehicle alignment sensor system Vehicle alignment sensor system

2001-03-16

2002-11-19

Buczinski, Stephen C. (Department: 3662)

Optics: measuring and testing

Angle measuring or angular axial alignment

Wheel alignment with photodetection

C033S203120

Reexamination Certificate

active

06483577

ABSTRACT:

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
BACKGROUND OF THE INVENTION
This invention relates to vehicle wheel alignment system, and in particular to improved sensors in a vehicle wheel alignment system.
Proper alignment of wheels in a vehicle is important for proper handling of the vehicle and proper tire wear. The alignment of a vehicle's wheels is performed primarily by adjusting camber, caster, steering axis inclination (SAI) and toe. It is known that toe alignment angles may be measured by placing sensor heads on each wheel of the vehicle to form pairs which extend across the front of the vehicle and along each side of the vehicle. Each sensor head has an emitter and a receiver. A sensor head emits a signal which is transmitted to the receiver of the other sensor head of that pair. The receiver converts this signal into a value which is indicative of the corresponding toe alignment angle of the vehicle. Thus, wheel alignment sensors have operated using essentially similar cooperative pairs of emitter and detectors wherein a detector, mounted on one wheel, actively senses the angle of its line of sight to its corresponding emitter mounted on an adjacent wheel. In order to perform a four wheel alignment three of these cooperative pairs of sensors are required as shown in U.S. Reissue Patent No. 33,144 to Hunter et al.
The signal presently used in these sensor heads is an electromagnetic signal in the visual or infrared range (hereinafter, referred to as light). The light impinges upon a sensing device in the receiver whose output is representative of the measured angle.
Currently, photodiodes, as set forth in U.S. Pat. No. 4,302,104, which is incorporated herein by reference, and linear array type charge coupled devices (CCDs), as set forth in U.S. Pat. No. 5,018,853, are used as the receiver.
U.S. Pat. No. 4,879,670 to Colarelli describes a gravity-referenced inclinometer for use in measuring vehicle wheel alignment angles. FIG. 1A of the '670 Colarelli patent illustrates the mounting of such an inclinometer to a vehicle wheel for measuring the camber angle of the wheel. The use of gravity-referenced inclinometers to measure camber is conventional, and assumes the vehicle rests, while being measured, on a surface which is both flat and level.
Society of Automotive Engineers (SAE) Publication 850219, entitled “Steering Geometry and Caster Measurement”, by January, derives and discusses the procedures and methods by which the toe angle and gravity-referenced alignment transducers are utilized to determine the caster and steering axis inclination (SAI) angles of a vehicle. The procedures described therein are the industry standard for conventional wheel alignment measurements.
Although the individual detector sensor assembly construction and operation can vary, a conventional prior art example is depicted in
FIGS. 1-4
. The view of
FIG. 1
is of a passenger vehicle
14
which will serve to illustrate the utility of the presently preferred embodiment of the invention. As seen from the left side, the left steerable wheel
15
L is shown in association with one form of an instrument support
16
adapted to grip the flange of the wheel rim. The support
16
carries a pivotal housing
17
the axis of which is substantially centerable to the spindle axis (not shown) on which the wheel
15
L rotates. A bracket
18
is hung from the housing
17
so it may assume a substantially vertical position even though the wheel
15
L is jacked up so it may rotate. At times, with the wheel
15
L resting on its support, it may be desirable to secure the bracket
18
against pendulous movement by tightening up on a knob
19
(FIG.
2
). The bracket
18
, in addition to the housing
17
, carries a support arm
20
which extends forwardly of the housing
18
to clear the tread of wheel
15
L and be in position so that its end portion may be used for supporting an instrument device
21
L. The support arm
20
, or some associated part of the assembly, is usually provided with a spirit level (not shown) for purposes of locating the sensor assembly in a known orientation, which is retained by tightening up on the knob
19
.
Further shown in
FIG. 1
is the vehicle non-steerable wheel
22
L to be provided with an instrument support
16
which is identical to the support attached to the steerable wheel
15
L. The several parts are designated by similar reference numerals and need not be described again. It is particularly important to observe that the support
16
at the left steerable wheel
15
L carries an instrument
23
L and the support
16
for the left non-steerable wheel
22
L carries a companion instrument
24
L. These instruments
23
L and
24
L are made up of cooperating components which are intended to function with each other in a manner set forth in U.S. Pat. No. 4,19,838 to Grossman, et al.
FIG. 2
shows a schematic plan view of all vehicle wheels, such as those at the left side seen in
FIG. 1
, and companion right side wheels
15
R and
22
R. The wheels at the left side are distinguished by adding the suffix “L”, and those at the right side are distinguished by the suffix “R”. However, each wheel
15
R and
22
R is provided with an instrument support
16
having the construction generally described above. Also, the support
16
on steerable wheel
15
R has a support arm
20
which carries an instrument
21
R to cooperate with the left side instrument
21
L. In addition, the support
16
at the non-steerable wheel
22
R carries an instrument
24
R to cooperate with an instrument
23
R carried by the support
16
at the steerable wheel
15
R. These instruments
21
L and
21
R, as well as instruments
23
R and
24
R, cooperate with each other and are made up of components operating in a manner described in the ′838 Grossman et al. patent.
In view of
FIG. 2
, the instruments
21
L and
23
L are in communication into a console assembly
25
, such as by cables
26
L and
26
R, or by a conventional wireless communications system, and in like manner, the instruments
24
L and
24
R are in communication with console
25
. Signal processing and alignment computation are performed in the console
25
and the results can be displayed by means indicated collectively at
28
. More particularly in
FIG. 2
, the instruments
21
L and
21
R cooperate with each other in the process of measuring the angles LWT (left wheel toe) and RWT (right wheel toe). For that purpose instrument
21
L has radiant energy detector means which is responsive to a source of radiant energy from instrument
21
R, and instrument
21
R has radiant energy detector means responsive to a source of radiant energy from instrument
21
L. The essence of this cooperation is that projectors of radiant energy are disposed to direct beams in criss-cross paths transversely of the vehicle, and which paths have boundaries within the field of vision of the detector means arranged to look at the position from which the beam is projected.
In a like manner, it is indicated in
FIG. 2
that instruments
23
L and
24
L, each containing radiant energy beam projectors and radiant energy detectors, cooperate with each other in the process of measuring the respective angles relative to a vehicle reference axis
30
which is established by a line joining the center points of the axles
31
and
32
, which center points are centered between the spacing of the wheel sets
15
L and
15
R, and
22
L and
22
R. The angle LFW is formed between the axle
31
and the longitudinal line-of-sight L of the radiant energy beam from the instrument
24
L at wheel
22
L. The angle LRW is formed between the axle
32
and the longitudinal line-of-sight L of the radiant energy beam from the instrument
23
L at wheel
15
L. Similarly, the instruments
23
R and
24
R cooperate with each other for measuring the angles RFW and RRW by the criss-crossing of the radiant energy beams depicted by the dash line R representing the longitudinal line-of-sight between the detector means in the instruments
23
R and
24
R. In the exam

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