WO1996016313A1

WO1996016313A1 - Motor vehicle wheel geometry test stand

Info

Publication number: WO1996016313A1
Application number: PCT/IB1995/001047
Authority: WO
Inventors: Gilles Scherrer
Original assignee: Gilles Scherrer
Priority date: 1994-11-23
Filing date: 1995-11-22
Publication date: 1996-05-30
Also published as: FR2727199A1; AU3854195A

Abstract

A motor vehicle wheel geometry test stand fitted with measuring equipment and vehicle carrying equipment, and having a construction which essentially consists of a prefabricated self-supporting structure (1) made of reinforced or prestressed concrete defining an equipment pit (5) accessible to operators. The measurement apparatuses (32) each comprise a head (35) that is movable sideways relative to the stand, and a system for measuring the movement of each head. Additional concrete members (8) may be prefabricated and added to the structure (1). The structure is mounted on a foundation bed (55), preferably by means of adjustable legs (57), and may later be height-adjusted and moved as required.

Description

WHEEL GEOMETRY CONTROL BENCH OF A MOTOR VEHICLE

The present invention relates to a test bench for the geometry of the wheels of a motor vehicle provided with two front steering wheels and at least two rear wheels, comprising: a horizontal drive surface, a rigid support structure, resting on a foundation and arranged to support devices and the vehicle resting on the drive surface, at least four support devices mounted on the support structure and arranged to each support a wheel of the stopped vehicle in a measurement position of the vehicle, the support devices arranged for supporting the steering wheels each having a roller unit which is capable of pivoting about a vertical axis when the corresponding wheel turns, and measuring devices mounted on the support structure and comprising at least four measuring devices measurement taken, each arranged in correspondence of an outer side of one of the vehicle wheels and provided with a palp movable ors arranged to be applied against said flanks of the wheels in the measuring position.

The invention applies particularly, but not exclusively, to factory test benches. In general, such a bench is provided at the end of a production or assembly line for motor vehicles, to control a certain number of parameters of the geometry of the wheels, to automatically edit a control sheet and signal deviations out of tolerance so that non-compliant vehicles are taken off the line. At least one other bench of the same kind is provided offline to perform a more complete check and the necessary corrections and adjustments on vehicles found to be non-compliant on the first bench.

The usual construction of such a control bench comprises a reinforced concrete tank which is poured on site and serves as a foundation and enclosure for a metallic support structure carrying the apparatuses, a drive platform and the vehicle placed on this platform. This structure must have a very high rigidity to allow the required measurement precision, which can be of the order of a hundredth of a millimeter in some cases. In addition, measures must be taken to prevent vibrations from nearby activities in the factory from being transmitted to measuring devices and vehicles. Consequently, the metal structure is very heavy and bulky, the concrete tank is large and expensive, and the construction of such a bench requires several months and can immobilize during this time the activity of an entire part of the factory. In addition, in the event of a factory or production line transformation, it is generally necessary to change the location of the online test bench. With conventional construction, this requires not only the dismantling and transfer of the devices and the metal structure, but also the construction of a new concrete tank and the demolition of the old one.

However, there are test benches that can be moved relatively easily. Such a bench is described in particular in the European patent application published under No. EP-A-0 310 520. This document describes a bench for measuring the parallelism of a train of wheels of a motor vehicle, this bench * • »Crr. * ar.! essentially of a pri-tar mechanically welded frame. ^» T '. * ^ U side two rolling sets. This bench compcr * "- ^" .rmr "- 'two centering devices and a return system by po iie. he realization of such a measurement bench requires the manufacture and assembly of a large number of parts. This involves a relatively large cost. In addition, bench maintenance is long and costly. Finally, the operation of this type of bench can only be automated with difficulty and at high cost.

There is also a relatively easy to move inspection pit, described in the German publication DE-A- 3 03 163. This publication describes a measurement or working pit composed of different prefabricated elements connected to each other during mounting in a excavation provided for this purpose. This pit cannot receive a vehicle geometry test bench. The present invention aims to create a control bench making it possible to substantially avoid the aforementioned drawbacks of conventional construction, in particular by virtue of a simple, rigid and space-saving support structure, allowing a very rapid and less costly construction method. .

To this end, the invention relates to a control bench of the type indicated in the preamble, characterized in that the support structure comprises a self-supporting prefabricated reinforced or prestressed concrete box, open upwards and comprising a bottom arranged to rest on the foundation, side and front walls which define a pit with the bottom, and bearing surfaces for the supporting devices and the measuring devices, and in that the measuring devices each have a head movable transversely to the bench and a system for measuring the displacement of each of the heads.

Thus, such a prefabricated self-supporting box alone fulfills most of the functions of the metal support structure and of the concrete tank of the test benches according to the prior art. During the construction of the bench, the work of "een. ** <ιvι. on site are limited to the maximum, since it suffices to r - ririr: _* . '. "- e xcavation just sufficient to receive the preîβ box * r, - *," *. * "* Raze a layer of foundation at the bottom of the excavation. horir r.ta.e, adapted to the nature of the basement, then to place on this couc he prefabricated brick box, which can be brought simply by means of one or two simple gantry cranes. This installation method also allows the horizontality and the level of the box to be adjusted. We can then directly backfill the balance of the excavation around the box and mount the devices on it, without using a complex and heavy metal structure. The support structure thus obtained has very little thermal expansion and can easily be isolated from the sources of surrounding vibrations, which favors the precision and reliability of the measurements. In cases where the location of the test bench must change, it is possible to take the prefabricated box out of the ground and reuse it at the new location. Preferably, the box is provided with anchors for suspension members for handling and transport.

In order to limit its dimensions for transport, the support structure may include one or more additional concrete elements, which are prefabricated separately from the box and assembled thereon in a monolithic manner. Said additional elements may comprise at least one pair of side brackets each provided with a bearing surface for one of the measuring devices. An additional element may be a headlight adjustment table, disposed above a front end of the pit to form a part of said drive surface and provided with transverse grooves for support rails of a measuring device.

In an advantageous embodiment, the box has at least one access opening made in one of its lateral or front walls.

Preferably, the bottom of the box is provided with level adjusting members capable of bearing on the foundation. Each of said level adjusting members may include an internally threaded sleeve embedded in the concrete at the bottom, and an adjustable foot by screwing into the sleeve.

In an advantageous embodiment, a bed of sand or mortar is placed between the foundation and the bottom of the box. A polymer seal preventing the transmission of vibrations can be placed around the support structure at the drive surface.

In cases where the rear wheels of the vehicles to be inspected are not steerable or steerable, the rear wheel support devices may simply comprise, at the level of the drive-over surface, plates with lateral clearance which are mounted on rollers or balls . To control vehicles with steerable or steerable rear wheels, provision may be made for the Rear wheel support devices each include a roller unit which is adjustable in longitudinal position and capable of pivoting about a vertical axis.

In a preferred embodiment, the measuring devices comprise at least three body height measuring devices (ground clearance), which are mounted on the side walls of the box.

Preferably, an exhaust gas suction block, forming part of the drive-over surface, is mounted on a rear end of the box, outside and in extension thereof, and comprises at least one hatch d suction can be opened and closed.

Other characteristics and advantages of the present invention will be presented in the following description of an exemplary embodiment, with reference to the appended drawings, in which:

FIG. 1 is a general perspective view of an embodiment of a control bench according to the invention. in which the surrounding land is not represented f aï m * "". let see the buried parts,

FIG. 2 is a partial view in per spec t ive of the prefabricated self-supporting box of the control bench of FIG. 1,

FIG. 3 is a schematic cross-sectional view of the box resting on its foundation,

FIG. 4 is a detailed view showing a body height measurement device, fixed to the concrete box, and

Figure 5 is a schematic view in vertical section of an exhaust gas suction hatch, mounted at the rear of the self-supporting box.

Referring to Figure 1, the geometry control bench for wheels of a motor vehicle has a rigid support structure of reinforced or prestressed concrete, formed mainly by a self-supporting box 1 open upwards and having a horizontal top surface which defines a drive surface 2 which can be accessed the vehicle to be checked. Box 1 has vertical side walls

3 and front

which surround a central pit 5 which staff can access, for example through one or more openings 6, 7 made in the walls of the box and communicating with an external staircase (not shown). The support structure also comprises additional elements made of reinforced or prestressed concrete, here comprising a pair of front side consoles 8, a pair of rear side consoles 9 and a headlight adjustment table 10 covering the front of the pit 5 and forming part of the road surface 2. These additional elements are prefabricated separately and, after the installation of the box 1, are mounted and rigidly fixed thereon to form with it a monolithic support structure. In general, this structure is buried up to the level of the drive surface 2, corresponding for example to ground level in a hall for mounting vehicles to be checked. To support this structure, the box 1 has a flat bottom 11 which rests on an appropriate flat foundation, as will be described later. Inside the pit 5, the bottom surface 11 can have a longitudinal and transverse slope in order to ensure the flow of the liquids towards a sump (not shown) in a corner of the pit.

As shown in FIG. 2, the central pit 5 extends longitudinally in the box 1 and has, roughly in the middle of its length, two opposite lateral niches 13 whose role will be explained later. Along pit 5, two horizontal grooves

\ and 15 are made in the concrete of each side wall 3 to respectively contain electric cables and light bars. Above each side wall 3, the box 1 has two horizontal bearing surfaces for devices, namely a front bearing surface 16 and a rear bearing surface

17. Each rear console 9 also has a horizontal support surface 18 situated lower than the drive surface 2. Each front console 8 (FIG. 1) has a horizontal bearing surface 19 at the level of the drive surface. This drive surface is formed in part by equipment mounted on the bearing surfaces 16 and 17. In the example shown here, this equipment comprises, on each side of the pit 5 "a rear platform 20 made of removable boards placed on a light metal frame 21 resting on the support surface 17, a front platform 22 provided with a metal frame resting on the support surface 16, and a liftable hatch 23 forming a bridge between the plates -forms 20 and 22 above the niche 13. This hatch is mounted by hinges on the frame 21. At the rear, the drive surface 2 also extends on a suction block 24 disposed externally in front of the end of the box 1 and provided with two liftable hatches 25 for the suction of the exhaust gases from the vehicle occupying the control bench.

To support the vehicle wheels approximately at the level of the road surface 2 during the measurements, there is provided a pair of roller support devices 26 for the front wheels and a pair of roller support devices 27 for the rear wheels. .

Each support device 26 appears in an opening of the front platform 22 and at least one of its two rollers is driven hydraulically so as to be able to rotate the front wheel supported by the device. In known manner, the rollers are mounted on a pivoting plate 28 resting on a fixed base plate 29 by means of a ring of balls so as to be able to pivot around a vertical axis. The pivoting plate 28 can be locked in the zero position by an appropriate mechanism and, when it is released, benefits from a radial clearance to avoid exerting transverse forces on the wheel.

In the present example, each rear support device 27 is similar to support devices 26, to allow the control of vehicles having steerable or steerable rear wheels. However, it is mounted movably longitudinally on rails 30 placed on the bearing surface 17, in order to be adaptable to different wheelbases of the vehicles to be checked. If the appliance 27 must be moved, we will also move the required number of boards from platform 20.

In cases where the rear wheels of the vehicles to be inspected are not steerable, each rear support device 27 and the platform 20 can advantageously be replaced by at least one horizontal plate with lateral movement, forming part of the drive surface 2 and supporting the corresponding wheel during the measurements. The possibility of lateral movement of such a plate, in particular thanks to an assembly on rollers or balls, makes it possible to release any transverse forces acting on the wheels, in order to eliminate them during the measurements.

Four measuring devices 32 are arranged each opposite the outer side of one of the wheels of the vehicle when the latter is in the measuring position, that is to say when the wheels rest on the support devices 26 and 27. These devices 32 are of a known type and are therefore not described in detail here. Those which correspond to the front wheels are mounted on the bearing surfaces 19. Those which correspond to the rear wheels are each mounted on a carriage capable of being moved and locked on longitudinal rails 33 mounted on the bearing surface 18, to adapt to different wheelbases of vehicles. Each device 32 comprises a base box 3 <, a head 35 movable on the box 34 in the transverse direction of the bench to approach and move away from the wheel, a system for measuring the displacement of each of the heads, and a support in star 36 with three or four arms each carrying a roller feeler 37 which is applied against the outer side of the tire of the wheel. The measurement system makes it possible to precisely determine the position of the vehicle's wheels relative to the bench. This also makes it possible to center the vehicle precisely and to easily automate the entire measurement. The support 36 is provided with a disc (not shown) materializing a plane parallel to the wheel and cooperating with sensors whose signals indicate the orientation of this plane in space.

Figure 4 shows another device known in such benches. control, namely a body height measuring device 40 which is provided with a head 41 movable vertically by means of a pneumatic cylinder 42 to apply against a predetermined point of the vehicle body in order to measure its level. This level is indicated by means of a linear potentiometer 43 cooperating with the rod of the jack 42. The device 40 is supported by a pivoting and exten¬ sible arm 44 mounted on a support 45 which, in the construction according to the invention, can be fixed directly to the corres¬ pondant side wall 3 of the concrete box 1. Normally, there are four devices for measuring the height of the body 40, two at the front and two at the rear, but it suffices to perform the measurements with three of them to determine the position in space of a reference plane of the body. These devices are not shown in Figure 1 for reasons of clarity of the drawing.

As required, a conventional headlight control device 46 can be installed on the table 10, provided with two transverse grooves 47 in which precision rails 48 can be mounted on which the device 46 circulates. such a device is not provided, the grooves 47 can be filled with pieces of wood to facilitate the passage of vehicles. It will also be noted that two retractable stops 49 are arranged in the front platforms 22 to retain, if necessary, the front wheels of the vehicle taking place on the control bench.

The exhaust gas suction block 24 mounted at the rear of the box is shown diagrammatically in FIG. 5. This block comprises two suction hatches 25 in the shape of a triangular box, which are mounted on horizontal hinges 50 and tilt together according to arrow A under the effect of pneumatic cylinders 51 to take an open position 25a above the drive surface 2. This position shows the perforated front face 52 of each hatch. The interior of each hatch is connected by a flexible pipe 53 and a valve (not shown) to a gas suction device. The valves make it possible to select the hatch 25 on the side where the vehicle's exhaust pipe is located, so that the gases are sucked in only by this trap there. When the hatches 25 are closed, they are suitable for vehicles.

The operation of the control bench described above is analogous to that of a conventional control bench and will therefore not be described in detail here. In the case of a production line control bench, the vehicle to be checked accesses the drive surface 2 from the rear, passing over the suction block 24, stops in the measurement position with its wheels on the support apparatuses 26 and 27, and leaves after the measurements by passing over the table 10. The set of functions of the control bench is managed by a computerized central unit (not shown) which processes and records the measurements. The operator has control and monitoring elements such as display screens which are arranged partly in the pit 5 and partly in the central unit arranged outside.

As soon as the vehicle is in the measurement position, this fact is noted by suitable detectors, the stops 49 are lowered, the suction hatches 25 are raised and one of them comes into operation. The operator identifies the vehicle by reading a bar code. The first measurement carried out is the control of the height of the body by the devices 40. This thus controls not only the ground clearance, but also the position in space of a reference plane, of which a deviation in position can indicate a mounting. defective of an element of the vehicle. If this measurement is out of tolerance, the vehicle must be checked more thoroughly and adjusted on another test bench. Then, the heads 35 of the four measuring devices 32 move to apply their feelers 37 against the outer flanks of the four wheels with a predetermined bearing force. This makes it possible to measure, in known manner, a series of parameters of the geometry of the wheels and of the direction, in particular by rotating the front steering wheels by means of the rollers of the support devices 26, then by orienting these wheels in different positions at using the steering wheel. For production control, it is customary to check the parallelism to the left and right, the camber, the caster angle, the maximum turning to the left and right and the trajectory angle. It is also expected that the operator can perform a parallelism adjustment on each front wheel by placing himself in the corresponding recess 13 and lifting the hatch 23 to access the member to be adjusted. At the same time, it can follow the progress of the corresponding measurement on a screen placed in the niche 13. If necessary, at the end of the control, the headlight control device 46 can be brought successively in front of each headlight, then laterally retracted to let the vehicle out.

An offline control and adjustment bench, to allow more in-depth control of vehicles found to be non-compliant on the production control bench, can be arranged essentially like the bench described above, but the operator can make the necessary adjustments to the suspension and steering components of the vehicle from the pit 5. This may be fitted with additional control and display devices, as well as the corresponding wiring, without transformation of the concrete support structure.

As explained above, one of the essential advantages of a test bench according to the invention lies in the simplicity, the speed and the low cost of its construction. Figure 3 shows that the self-supporting box 1 rests on a foundation 55 by means of a sand bed 56 and, if necessary, two or more pairs of adjustable feet 57 engaged in threaded sleeves 58 embedded in the bottom 11 of the box. For example, four of these sleeves 58 can be arranged near the corners of the box.

The foundation 55 is produced at the bottom of a minimal excavation, the lateral slopes 60 of which have been shown. Its nature is chosen according to the local quality of the subsoil and may vary, depending on the case, between a simple layer of sand or of lean concrete, a concrete slab poured directly on the ground or, exceptionally, a slab slab. However, as the box 1 is self-supporting, the foundation 55 is hardly larger than the bottom 11 of the box and is not subjected to high stresses, therefore it is generally not very thick and quickly constructed. Since the excavation is not very wide, the box 1 can be transported by means of gantry cranes which pass astride the excavation and make it possible to lower the box 1 on the foundation 55, the box being provided with anchors 59 for the means of suspension of the gantries. The level and the horizontality of the box are adjusted by screwing or unscrewing the feet 57 from the interior of the pit 5, then the layer of sand 56 is put in place by blowing and one can immediately backfill at least the lower part of the excavation. If necessary, it is at this stage that the additional precast concrete elements are mounted, such as the brackets 8 and 9, which are supported by inclined metal crutches 61 cooperating with support pieces embedded in the concrete. The rigid connection between the additional elements and the box 1 can be made by known means such as bolting, sealing of studs, etc. . Thanks to prefabrication, as soon as the installation of the concrete support structure is complete, the devices can be mounted there. The necessary wiring may even have been done beforehand. Preferably, the support structure of the control bench is separated from the surrounding structures, for example from a slab 62 forming the floor of a factory, by means of a polymer joint 63 which prevents the transmission of vibra¬ tions, deflection or other movements which may affect the measurements. This also allows a subsequent leveling of the concrete support structure if it has undergone settlement, this operation being carried out by means of adjustable feet 57. Holes can be provided in the bottom 11 to allow wedging injections or consolidation.

Another advantage of the monolithic support structure of the test bench according to the invention is that, if the location of the test bench has to change, it is possible to move the support structure to reuse it at the new location, in particular thanks to to the anchoring members 59 provided for suspending the caisson 1. This results not only in saving on materials and civil engineering works, but also a considerable gain in the duration of the works and the downtime of the test bench .

Claims

1. Bench for checking the geometry of the wheels of a motor vehicle with two front steered wheels and at least two rear wheels, comprising:

\ - a horizontal road surface (2),

- a rigid support structure (1, 8, 9, 10), resting on a foundation and arranged to support devices and the vehicle resting on the road surface, - at least four support devices (26, 27) mounted on the support structure and arranged to each support a wheel of the stopped vehicle in a vehicle measurement position, the support devices (26) arranged to support the steering wheels each having a roller unit which is capable of pivoting around a vertical axis during a turning of the corresponding wheel,

- And measuring devices, mounted on the support structure and comprising at least four measuring devices (32) each arranged in correspondence with an outer side of one of the wheels of the vehicle and provided with movable feelers (37) arranged to be applied against said flanks of the wheels in the measuring position, characterized in that the support structure (1, 8, 9, 10) comprises a self-supporting box (1) prefabricated in reinforced or prestressed concrete, open towards the top and comprising a bottom (11) arranged to rest on the foundation (55), side and front walls (3, 4) which define a pit (5) with the bottom, and bearing surfaces (16-19 ) for the support devices and the measurement devices, and in that the measurement devices (32) each comprise a head (35) movable transversely relative to the bench and a system for measuring the displacement of each of the heads.

2. Control bench according to claim 1, characterized in that the box (1) is provided with anchors (59) for suspension members for handling and transport.

3. Test bench according to claim 1 or 2, characterized in that the support structure comprises one or more additional elements (8, 9 "10) made of concrete, which are prefabricated separately from the box (1) and assembled therewith. here in a monolithic way.

4. Test bench according to claim 3, characterized in that said additional elements comprise at least one pair of side brackets (8, 9) each provided with a bearing surface (18, 19) for one of the devices of measurement.

5. Control bench according to claim 3, characterized in that an additional element is a headlight adjustment table (10), disposed above a front end of the pit (5) to form a part of said surface suitable for vehicles and provided with transverse grooves (47) for supporting rails of a measuring device (46).

6. Test bench according to one of the preceding claims, characterized in that the box (1) has at least one access opening (6, 7) formed in one of its side or front walls.

7. Test bench according to one of the preceding claims, characterized in that the bottom (11) of the box is provided with level adjustment members (57, 58) capable of bearing on the foundation (55).

8. Control bench according to claim 7, characterized in that each of said level adjustment members comprises a sleeve (58) internally threaded, embedded in the concrete of the bottom (11), and a foot (57) adjustable by screwing in the sleeve.

9. Test bench according to one of the preceding claims, characterized in that a bed of sand or mortar (56) is placed between the foundation and the bottom of the box.

10. Test bench according to one of the preceding claims, characterized in that a polymer seal (63), preventing the transmission of vibrations, is arranged around the support structure at the level of the drive surface (2 ).

11. Test bench according to one of the preceding claims, characterized in that the rear wheel support devices comprise, at the level of the drive surface (2), plates with lateral clearance which are mounted on rollers or balls.

12. Test bench according to one of claims 1 to 10, caracté¬ ized in that the support devices (27) of the rear wheels each comprise a roller unit which is adjustable in longitudinal position and capable of pivoting around. a vertical axis.

13. Test bench according to one of the preceding claims, characterized in that the measuring devices comprise at least three body height measuring devices (40), which are mounted on the side walls (3) of the box.

14. Test bench according to one of the preceding claims, characterized in that an exhaust gas suction block (24), forming part of the drive surface, is mounted on a rear end of the box (1 ), outside and in extension thereof, and comprises at least one suction hatch (25) suscep¬ tible to be open and closed.