Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B11/00—Measuring arrangements characterised by the use of optical techniques
  • G01B11/26—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes
  • G01B11/275—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes for testing wheel alignment
  • G01B11/2755—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes for testing wheel alignment using photoelectric detection means
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B2210/00—Aspects not specifically covered by any group under G01B, e.g. of wheel alignment, caliper-like sensors
  • G01B2210/10—Wheel alignment
  • G01B2210/16—Active or passive device attached to the chassis of a vehicle
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B2210/00—Aspects not specifically covered by any group under G01B, e.g. of wheel alignment, caliper-like sensors
  • G01B2210/10—Wheel alignment
  • G01B2210/20—Vehicle in a state of translatory motion
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B2210/00—Aspects not specifically covered by any group under G01B, e.g. of wheel alignment, caliper-like sensors
  • G01B2210/10—Wheel alignment
  • G01B2210/24—Specially developed for using with trucks or other heavy-duty vehicles
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B2210/00—Aspects not specifically covered by any group under G01B, e.g. of wheel alignment, caliper-like sensors
  • G01B2210/10—Wheel alignment
  • G01B2210/28—Beam projector and related sensors, camera, inclinometer or other active sensing or projecting device
  • G01B2210/283—Beam projectors and related sensors
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B2210/00—Aspects not specifically covered by any group under G01B, e.g. of wheel alignment, caliper-like sensors
  • G01B2210/10—Wheel alignment
  • G01B2210/30—Reference markings, reflector, scale or other passive device
  • G01B2210/303—Reference markings, reflector, scale or other passive device fixed to the ground or to the measuring station

Definitions

• the present invention relates to a system for measuring the settings of vehicle wheels, said system comprising a holder which is attached to the outside of each individual wheel or wheel-pair and which is provided with a trunnion means which is intended to be aligned with the rotational axis of said wheel or wheel-pair, a light beam source, such as a laser projector, mounted on said trunnion means on the side of the vehicle in a plane common with the longitudinal axis of the vehicle and functioning to illuminate alternately at least two measuring scales which are arranged at respective ends of the vehicle and extend transversely to the longi ⁇ tudinal axis of the vehicle equidistant from the longi ⁇ tudinal centre line of said vehicle.
• a light beam source such as a laser projector
• the invention is a further development of the measuring system described and illustrated in Swedish Patent
• each rod is attached at its outer ends with a respective lateral measuring scale whose zero points lie equidistant from the longitudinal centre line of the chassis.
• the zero points lie slightly outside the wheels, so as to provide a free line of sight from scale to scale, outwardly of the outer sur ⁇ faces of the wheels.
• a sighting instrument is mounted perpendicularly to the geometric axis of rotation.
• the method is based on generating a sighting line transversely to the extension of the wheel-axle rotational axis and essentially in a plane which is common to the longitudinal axis, and by mutually compar ⁇ ing the optical extensions of the sighting lines to respective measuring scales in both directions with regard to the positions of the points in relation to the longitudnal axis. Deviation between the positions indicates that the wheel rotates obliquely to the longitudinal axis of the vehicle.
• each measuring scale consist of an optoelectronic detector unit which includes a plurality of discrete photoelements mounted in a relatively long row on a circuit card or board; and in that the photoelements are connected conductively to a microprocessor which is mounted on the circuit card and which functions to detect and compare the intensity of the light emitted by respective photoelements when said elements are irradiated with light and to produce information relating to the precise position of the light beam incident on the measuring scale.
• the present invention is also characterized in that the measuring scale has fixedly mounted therein a diffusor which functions to distribute the light intensity over a plurality of photoelements; and in that the micro- processor functions to compare the intensity of the light emitted by respective photoelements and to cause the measuring result to be indicated on a display con ⁇ nected to the measuring scale, subsequent to having calculated the centre-of-gravity of the broadened inten- sity curve.
• the measuring result can be transferred to a separate com ⁇ puter connected conductively to the measuring scale and capable of indicating individual measuring results in a known manner and also of storing said results and com ⁇ bining separate part-measuring results in a known manner for presentation of a calculated result for a relevant wheel setting.
• the measuring scales of the inventive measuring system may be mounted on separate stands located outside the respective ends of the vehicle, and one or more measur ⁇ ing scales may be mounted adjacent the vehicle. All of the measuring scales are positioned so as to have the same lateral positions in relation to the vehicle centre line, irrespective of the positions of respective mea ⁇ suring scales in the longitudinal direction of the vehicle.
• the inventive measuring system comprising measuring scales which are mounted on the vehicle concerned and a separate computer which is placed within said vehicle would enable wheel settings to be measured while the vehicle is in motion, which would be highly advanta- geous.
• Figure 1 is a simplified view from above of a vehicle whose wheels are to be checked with the aid of an inventive measuring system
• Figure 2 is a longitudinal, schematic view of a measur ⁇ ing scale provided with a row of photo ⁇ elements, and a microprocessor
• Figure 3 is a cross-sectional view of the measuring scale
• Figure 4 illustrates the detection principle of the measuring scale.
• Figure 1 illustrates schematically the measuring system applied to a vehicle having a chassis frame 10, two double-wheel rear wheels 11 and two front wheels 12.
• the rear wheels 11 are carried by a common axle 13 and each of the front wheels 12 is carried by an individual axle 14. Also shown in the Figure is the longitudinal centre line 15 of the vehicle, this centre line having great significance when checking and adjusting the wheel settings of a vehicle.
• a stand 16 is positioned at right angles to the longitu ⁇ dinal centre line 15 of the vehicle, at respective ends of the vehicle.
• Mounted on each stand 16 is a pair of continuous, self-centering measuring bars 17 which are able to take different lateral positions in relation to the vehicle centre line 15, these lateral positions being contingent on vehicle width.
• Mounted at the ends of respective measuring bars 17 are lateral measuring scales 18, which are placed far enough from the vehicle to obtain free sight from scale to scale, outwardly of the outer sides of the wheels.
• a light- beam source for instance a laser projector 4
• a laser projector 4 is pivot- ally journalled on the trunnion 7 on the holder and can be rotated on said trunnion 7 so as to irradiate each measuring scale 18 alternately. If the measuring scales show mutually the same values, the rotational axis 1 of the wheel is positioned perpendicular to the vehicle centre line.
• the measurement value of the rotational axis 1 of a wheel 12 on the forward measuring scales 18 is greater than the measurement value on the rearward measuring scale on the same side of the vehicle, there is obtained a positive value which is divided by the distance between the two measuring scales 18 and which gives a value of the rolling direction of the wheel per unit of length. If the measurement value on the rearward measuring scale is greater than the measurement value on the forward measuring scale on the same side of the vehicle, there is obtained, in an analogous manner, a negative rolling direction per unit of length (mm/m) . These measuring values can be used to ascertain whether or not the wheel angles toe-in or toe-out occur on the vehicle concerned.
• the aforedescribed part of the measuring system is similar to the measuring system described in Swedish Patent Specification No. 7316572-2. Wide differences exist, however, in the design and applicability of the measuring scales of the known and the inventive systems.
• the earlier, linear measuring scales are constructed to be hung on measuring bars mounted in a vehicle, and the measuring scales are graduated solely linearly for ocular reading.
• each measuring scale 18 has the form of an optoelectronic detector unit, which is comprised of an elongated, profiled body 19 having embracing walls 20, 21, 22 on three sides thereof.
• the fourth side, the upper side, is provided wi-th a longitudinally extending opening 28.
• the detector unit is provided with a linear metric graduations 29 along the imperforate sides of the open- ing 28, said graduations having a length greater than 30 cm.
• Each end of the body 19 is closed with an end plate 23
• a circuit board 24 mounted in the body 19 is a circuit board 24 on which a number of known electronic components are mounted. It is not necessary to know the nature of these components in order to obtain an understanding of the invention, and consequently these components will not be described here. Also mounted firmly on the circuit board 24 is a relatively long row of discrete photoelements 25, pref- erably phototransistors. These elements are connected conductively to a microprocessor 26, a so-called micro ⁇ chip processor, which detects the intensity of the light emitted by each separate photoelement 25 and, on the basis thereof, calculates the centre-of-gravity position of a beam incident on the measuring scale 18. The result of this calculation is passed to a display unit 27 attached indirectly to the circuit board 24 and which illustrates the result in digit form, in a known manner.
• the microprocessor 26 is also intended to activate an indicator lamp 33, when light impinging on the measuring scale 18 activates the microprocessor 26 for calculation of said gravitational centre position.
• the indicator lamp 33 is placed within the body 19 of the measuring scale, so as to be readily visible to the person carry ⁇ ing out the measurements. -
• the components of the measuring scale are powered electrically by a number of batteries 30 disposed within the body 19.
• an elongated lens 31 which magnifies the detector surface of the measuring scale 18, with the purpose of capturing possible movements of the beam source.
• the lens 31 has a low position in the opening 28, therewith protecting the lens 31 and also screening light which is obliquely incidental to the lens 31 and preventing said light from having any appreciable influence on the photoelements 25.
• a laser projector produces an intense, very narrow beam of coherent light, which impinges with high intensity on a very small area.
• the intensity distribution of the light beam is preferably such that the beam will illuminate, or irradiate, a plurality of mutually adjacent photoelements 25 on the measuring scale 18. This is achieved by mounting a diffusor 32 beneath the lens 31 in the body 19, so as to distribute incident light on the measuring scale 18 to the photo ⁇ elements 25.
• Figure 4a illustrates by way of example an intensity curve of a laser beam delivered by the laser projector 4.
• Figure 4b illustrates an intensity distribution curve containing the same amount of monochromatic light, and
• Figure 4c shows the same curve in larger scale.
• the curve 4c illustrates the intensity of the light emitted by a plurality of mutually adjacent photoelements 41-46 in the measuring scales 18 and detected by the micropro ⁇ cessor 26.
• the microprocessor 26 calculates the centre- of-gravity point of the intensity curve so as to estab- lish the exact position of the beam on the measuring scales 18 and produces output signals which indicate this position on the display in digit form.
• the inventive measuring system enables the wheel set ⁇ tings of a vehicle to be measured and ascertained while the vehicle is in motion.
• the measuring scales 18 are mounted on the vehicle equidistant from the vehicle centre line 15, and a computer unit is fitted within the vehicle and connected to respective measuring scales 18.
• the light beam may be generated by a source other than a laser, and photodiodes may be used as detectors in the measuring scale 18.
• the measuring result may also be reproduced in a manner different to that described in the specifi ⁇ cation.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Length Measuring Devices By Optical Means (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20382603

Family Applications (1)

Country Status (3)

Cited By (7)

Citations (2)

• 1991
  • 1991-04-30 SE SE9101303A patent/SE468369B/sv not_active IP Right Cessation
• 1992
  • 1992-04-23 WO PCT/SE1992/000266 patent/WO1992019932A1/en active Application Filing
  • 1992-05-20 TW TW81103927A patent/TW223039B/zh active

Patent Citations (2)

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