Apparatus and plant for testing subsystems including vehicle wheels and road transport pavements

Abstract

An apparatus for measuring performance and contact characteristics between a vehicle test wheel (10) and a ground (20), comprising: a motorized test cart (100) configured to move at a specified speed along a guideway (30) attached to the ground (20); a support (200) for the test wheel (10); and a mechanism (300) mounted between the test cart and the support (200) and configured to hold the support so that the test wheel (10) can roll on the ground (20) with the movement of the test cart along the guideway (30); and allow a movement of the support (200) relative to the ground (20) so that the test wheel (10) can be raised relative to the ground (20) or lowered until it contacts the ground; a thrust actuator (310) configured to apply a thrust force (320) between the test cart (100) and the support (200) and cause the support (200) to move toward the ground (20) through the mechanism (300) and to keep the test wheel (10) in contact with the ground (20) so that the wheel exerts a contact force (220) against the ground (20). The mechanism (300) is mounted between the test cart (100) and the support (200) so that the support (200) is cantilevered from the test cart (100) and the test wheel (10) is external laterally from the test cart (100); said test cart (100) comprises transport wheels (110, 120) mounted to make direct contact with the ground without contacting the guideway (30) and on which the test cart (100) rests; the test cart comprises a plurality of sliding constraints (130,140) between the test cart (100) and the guideway (30) configured to counterbalance the test cart (100) relative to the guideway (30) during the application of the thrust force (320) by the thrust actuator (310) and to isolate the application of the contact force (11) from ground contact reactions of the transport wheels (110, 120).

Description

TITLEAPPARATUS AND PLANT FOR TESTING SUBSYSTEMS INCLUDING VEHICLE WHEELS AND ROAD TRANSPORT PAVEMENTSDESCRIPTIONField of the invention[ oooi] The present invention relates to the field of wheeled transportation, and more specifically relates to an apparatus for performing tests that measure the interaction of vehicle subsystems with a pavement.

[0002] Specifically, the invention can perform tests on wheels, or on tires and related wheel treads, or it can also perform tests on vehicle subsystems comprising wheels, such as suspensions, supports, wheel axles, and determine their interaction with the pavement.

[0003] In addition, the invention can test road transport pavements, for verification of known pavements or for research of new pavements or new materials for them.

[0004] The invention relates, likewise, to a plant comprising test apparatus and a guide for carrying out tests.Background of the invention

[0005] Various types of machinery are known for testing vehicle wheels, particularly tires, such as those used by car and motorcycle tire companies, for determining the force-slip curve, both longitudinal and lateral.

[0006] Some types of test benches are built for specific size ranges, so multiple test benches are required to accommodate different tire sizes. In addition, they are often static test benches that interface with rollers with grip that differs from that of the real road, so additional systems are needed to correlate measured data with real cases.

[0007] A known type of machinery comprises a test cart that runs on a rail and on which a wheel with a tire is mounted. The test cart moves relativeto a test pavement. The test pavement can be under the test cart or lateral to the cart.

[0008] For example, in EP4049865A1 the cart moves on three rails. The contact interface between cart and rails is achieved by rollers, which also act as thrust bearings to compensate for tilting moments of the cart. The test pavement is arranged under the cart between two of the three rails. The load on the wheel is generated by a piston above the cart, which pushes a wheel support down or up to increase or decrease the load.

[0009] A similar solution with a load piston above the cart is described in KR102005187B1 , with only two rails forming a track and the test pavement between the rails below the cart. The track is developed to form a closed loop in a vertical plane, with curves of non-constant radius.

[0010] CN113063683A describes a system for comparing two different tire tests, one of which is indoor on an enclosed track extending in a vertical plane and one is outdoor on a pavement loop. In the outdoor one, a gantry test cart brings a pair of wheels into contact with the test pavement under the test cart which runs on a track.

[0011] KR101489239B1 provides a low-bulk measurement system for measuring tire actions on a surface formed by a belt on rollers. A tire is mounted to a wheel mounted to a cantilevered shaft of a cart moving forward on a track. The wheel is pushed down from above by a piston arranged on the cart.

[0012] LIS2011048120A1 describes a cart constrained to two rails elevated above the test pavement, supported by a gantry. The test pavement is arranged between the two rails and a measuring head is suspended from the cart and centrally located with respect to the two rails. The measuring head regulates the force between the wheel and the pavement.

[0013] US8474311 B2 and US8806931 B2 describe a gantry test cart running on a track on a test pavement, with constraints that allow only thetranslation of a wheel support parallel to the track. A hydraulic cylinder determines the vertical load. A method for comparing the values measured by the test machine with those found on the actual road is described.

[0014] CN102507218A involves a slide moving on a guide basement and carrying a robotic arm that moves a wheel support relative to an abrasive test pavement. The robotic arm controls vertical movements relative to the cart and also horizontal movements in conjunction with the slide.

[0015] Then, for characterizing the behaviour of vehicle components (e.g., suspensions), there are static test benches, e.g., "four-post rigs" as for example described in GB2494712, or other test benches as described in GB2541499, that measure the response of wheels and suspension to forces that simulate road bumps and that are simulated by actuators that, while holding the vehicle stationary, stress the wheels in the vertical direction.

[0016] However, there are no systems that allow for both tire testing and road test pavement testing.

[0017] It is also desirable to have a test machine capable of both fine- tuning tire set-up angles and performing behaviour characterization of different types of vehicle subassemblies, as well as accommodating different types of vehicle subassemblies, with wheels and tires even of very different sizes, from motorcycle use to heavy-duty use, for a variety of test pavements.Summary of the invention

[0018] In this description, when reference is made to a test wheel, it is meant to comprise tests on any interaction, through the wheel, of vehicle subsystems with test pavements, to perform tests on wheels, or on tires and their treads, or on entire vehicle subsystems comprising wheels, on individual suspensions or axles or bearings, etc., as well as to perform tests on the effect of test wheels on test pavement structures and road transportinfrastructure materials.

[0019] It is an object of the present invention to provide an apparatus for measuring performance and contact characteristics between a vehicle test wheel and a ground that meets the above aspects.

[0020] It is a special object of the present invention to provide such an apparatus that enables tests to be made without irregularities in sliding relative to the pavement affecting the measurements.

[0021] It is a special object of the present invention to provide such apparatus and a related plant that can be constructed in open environments in a durable manner.

[0022] It is a special object of the present invention to provide such apparatus that can perform tests on wheels and other vehicle subsystems of any size without the need for adaptations.

[0023] It is a special object of the invention to provide such apparatus that enables a test of a vehicle's wheel assembly by interfacing it with real test pavements even in the presence of distributed or concentrated obstacles or sectors with different grip, roughness, climatic and environmental conditions.

[0024] It is another special object of the invention to provide such an apparatus that is versatile to be used both to do tests on the interaction between tire and test pavement, in all its aspects, even whole vehicle subsystems such as quarter car, motorcycle fork and swingarm, in order to optimize the performance and reduce the fuel consumption of rubber-tired vehicles.

[0025] It is a further special object of the invention to provide such an apparatus that enables tests to be done to increase quietness, decrease rolling resistance of wheels, and increase efficiency of vehicles, allowing a more in-depth analysis of noise and vibration generated by the wheel assembly that is reflected on the vehicle and the external environment, particularly for electric vehicles.

[0026] It is also a particular object of the invention to provide such an apparatus to analyse the interaction of the vehicle-tire system so as to test mixtures of road test pavement components and construction techniques that provide the best performance in terms of grip, tire wear, and rolling resistance, and those that are most environmentally sustainable for the same performance.

[0027] These and other objects are achieved by an apparatus for measuring performance and contact characteristics between a vehicle test wheel and a test pavement as per claim 1 .

[0028] According to another aspect of the invention, the above objects are achieved by a system of an apparatus and a guideway to measure performance and contact characteristics between a vehicle test wheel and a test pavement as per claim 15.

[0029] Other technical features of the invention are defined in the dependent claims.

[0030] An apparatus for measuring performance and contact characteristics between a vehicle test wheel and a ground, according to the invention comprises:- a motorized test cart configured to move at a predetermined speed along a guideway fixed to the ground;- a support for the test wheel;- a mechanism mounted between the test cart and the support and configured to:- hold the support so that the test wheel can roll on the ground with the movement of the test cart along the guideway; and- enable a movement of the support relative to the ground so that the test wheel can be raised relative to the ground or lowered until it contacts the ground;- a thrust actuator configured to apply a thrust force between the testcart and the support and cause the support to move toward the ground through the mechanism and to keep the test wheel in contact with the ground so that the test wheel exerts a contact force against the ground; wherein the mechanism is mounted between the test cart and the support so that the support is cantilevered from the test cart and the test wheel is outside laterally from the cart; wherein the test cart comprises transport wheels mounted to make direct contact with the ground without contacting the guideway and on which the test cart rests;-the test cart comprises a plurality of sliding constraints between the test cart and the guideway configured to counterbalance the test cart relative to the guideway during the application of thrust force by the thrust actuator and to isolate contact forces from ground contact reactions of the transport wheels.

[0031] Advantageously, at least one pair of wheels of the transport wheels can be driving wheels, and at least one pair of the transport wheels can be a pair of steering wheels.

[0032] Advantageously, the support comprises at least one force sensor between the test wheel and the support, configured to provide a force signal proportional to the contact force.

[0033] Advantageously, there is a control unit connected with the thrust actuator and the sensor, the control unit being configured to change a thrust force exerted by the thrust actuator according to a force signal provided by the force sensor so that the contact force maintains a predetermined value as the test cart proceeds along the guideway.

[0034] Advantageously, the test cart is a gantry frame, with uprights to which the transport wheels are mounted.

[0035] Advantageously, the sliding constraints between the test cart andthe guideway comprise caster assemblies configured to slide on the guideway and comprise:- horizontal caster assemblies, configured to make contact on the guideway by rotating in horizontal planes, and are configured to compensate for displacements induced by centrifugal force and to hold up horizontal components of the test wheel interaction with the ground;- skewed caster assemblies arranged to make contact on the guideway by rotating in planes arranged at an angle to the ground to prevent a lift or tip-over of the test cart and to absorb vertical components of the interaction of the test wheel with the ground transmitted to the test cart through the support and the mechanism.

[0036] Advantageously, the horizontal caster assemblies and skew caster assemblies comprise springs / dampers arranged to absorb geometric irregularities in the guideway and maintain rolling contact with it.

[0037] Advantageously, the horizontal caster assemblies, comprise two caster wheels each, arranged to make contact on the guideway by rotating in horizontal planes, where the caster wheels are connected to a shaft by two connecting rods and a support plate integral with the shaft, each shaft being connected to the frame with pins that allow it to rotate about a vertical axis. The horizontal sliding constraints by means of the spring / damper suspension system and shaft tilting, transmit the trajectory imposed by the guideway to the frame.

[0038] Advantageously, the horizontal caster assemblies provide a linkage connected to the shaft and connected to a steering hub of the wheels on which the frame rests. In this way, the caster assembly and the linkage assembly cause the transport wheels to steer in a way that follows the guideway by essentially eliminating actions that could cause resistance to travel.

[0039] Advantageously, oblique sliding constraints comprise a pair ofrollers connected by a pair of connecting rods.

[0040] Advantageously, the support comprises sensors measuring the interaction of the test wheel with the ground.

[0041] Advantageously, the support comprises a support plate that is connected to upper and lower pivot arms, respectively, of the mechanism.

[0042] Advantageously, the support comprises a swivel fork connected to the support, a drift actuator being provided to cause controlled rotation of the test wheel to impose a predetermined drift angle.

[0043] Advantageously, the mount comprises a fork connected to a test wheel hub via a hinge, a camber actuator configured to arrange the test wheel according to predetermined camber angles being provided.

[0044] According to another aspect of the invention, a plant comprising a guideway and the apparatus as defined above, where the guideway is a reinforced concrete monorail having a root anchored to the ground, from the root extending a central parallelepiped portion and an upper portion, the central parallelepiped portion and the upper portion being configured to engage the sliding constraints of the cart.

[0045] Advantageously, the ground is configured to define adjacent to the guideway a transport wheel track, and a test pavement for the test wheel.

[0046] Advantageously, the guideway is arranged on the ground to form a closed flat path with straight and curved sections.

[0047] Advantageously, the test pavement comprises concentrated obstacles, such as potholes, bumps, sleepers, etc., configured to perform tests to characterize the behaviour of vehicle components, such as suspensions.Brief description of the drawings

[0048] The invention will be illustrated below with the followingdescription of an embodiment thereof, made by way of example and not for limitation, with reference to the attached drawings in which:Figure 1 shows an apparatus and a plant to measure performance and contact characteristics between a vehicle test wheel and a ground;Figure 2 shows a partial view of the apparatus in Fig. 1 in two operating positions;Figure 3, 4 show a plant of a guideway and an apparatus according to the invention;- figure from 5 shows a side view of the apparatus in Fig. 1 from a side opposite a head;Figure 6 is a cross section according to arrows VI-VI in Fig. 5;Figure 7 is a perspective view of the apparatus in Fig. 1 .embodiments

[0049] Referring to Figure 1 , an apparatus 1 for measuring performance and contact characteristics between a vehicle test wheel 10 and a ground 20 comprises a motorized test cart 100 configured to move at a predetermined speed along a guideway 30 attached to the ground 20. The speed of the test cart can be predetermined, such as up to 60km / h, or beyond, in a test section, or it can be varied according to the response of components being tested.

[0050] As noted above, although reference is made in the description to test wheel 10 mounted to apparatus 1 , it is clear that the invention can measure any interaction of vehicle subsystems with the ground 20, being able to perform tests either on wheels 10, or on tires and their treads, or tests on entire vehicle subsystems comprising wheels, on individual suspensions or axles or bearings, etc., as well as testing any test pavements for road transport infrastructure.

[0051] Always with reference to Figs. 1 and 2, the test wheel 10 is mounted to a support 200, and between the motorized test cart 100 and the support 200, a mechanism 300 is provided configured for:- holding support 200 so that the test wheel 10 can roll on the ground 20 with the movement of the test cart 100 along the guideway 30; and- allowing a movement of the support 200 relative to ground 20 so that the test wheel 10 can be raised from ground 20 or lowered until it contacts ground 20 with a predetermined force 11 (Fig. 2).

[0052] Specifically, mechanism 300 comprises a thrust actuator 310 configured to apply a thrust force 320 between test cart 100 and support 200 and to cause support 200 to move toward ground 20 through mechanism 300, as well as to keep test wheel 10 in contact with ground 20 so that test wheel 10 exerts contact force 11 (Fig. 2) against ground 20 during the movement of test cart 100.

[0053] According to a possible embodiment of the invention, the test cart 100 comprises transport wheels 110, 120 in direct contact with the ground and on which the test cart 100 rests. At least one wheel pair 110 of the transport wheels 110, 120 can be formed by driving wheels, and at least one wheel pair of the transport wheels 110,120 can be a pair of steering wheels.

[0054] None of the transport wheels 110,120 make contact with the guideway 30. In fact, the test cart comprises a plurality of sliding constraints 130, 140 between test cart 100 and guideway 30 configured to counterbalance test cart 100 relative to guideway 30 during the application of thrust force 320 by thrust actuator 310 and to isolate the application of contact force 11 from ground contact reactions of transport wheels 110, 120.

[0055] Support 200 can comprise sensors 210 arranged between test wheel 10 and support 200 and configured to transmit to a control unit 400 signals 211 proportional to the interactions of wheel 10 with ground 20. Specifically, sensors 210 can comprise force sensors and signals 211 can comprise signals proportional to the contact force 11 between tread 16 and ground 20. Sensors 210 can be mounted to a measuring head 220.

[0056] A control unit 400 connected with the thrust actuator 310 andsensors 210 is configured to change the thrust force 320 exerted by the thrust actuator 310 according to the force signal 211 provided by the sensors 210 so that the contact force 11 maintains a predetermined value as the test cart 100 proceeds along the guideway 30.

[0057] In possible embodiments, the guideway 30 can be a reinforced concrete monorail having a root 31 anchored to the ground 20 by means of masonry construction techniques, of a known type and therefore not described and illustrated in detail. A central parallelepiped portion 32 and an upper trapezoidal portion 33 can extend from root 31. The central parallelepiped portion 32 and the upper trapezoidal portion 33 can be made using building techniques with high geometric regularity without excessive cost, and with high durability over time, to allow the sliding constraints 130, 140 between the test cart 100 and the guideway 30 to exert optimal constraining reactions for making test measurements during the motion of test cart 100.

[0058] The trapezoidal portion 33 can alternately be a T-shaped portion. In that case, the sliding 140 constraints have casters 141 rotating in vertical planes, always in contact with the guideway 30 in the T-shaped portion.

[0059] Ground 20 can be a test pavement arranged to contour a specific plan geometry of the guideway 30, e.g. a closed pathway 35 that is essentially oval in shape with straight 36 and curvilinear 37 sections, as for example shown in Fig. 3. The curvilinear sections can also be non-circular, e.g., with increasing or decreasing radius. Alternatively, other arrangements of the guideway 30 can be provided, e.g., straight only, with a coming and going path of the apparatus 1 , for example as shown in Fig. 4, as well as any other shape.

[0060] Ground 20, as shown in Figs. 1 and 2, can comprise, for example, a transport track 21 , of width 21 a, of maximum surface evenness for transport wheels 110, 120, and a test pavement 22, of width 22a, which selectively can be configured for various types of tests. Of course, ground 20 can also be a uniform road pavement, without providing specific transportor test pavements.

[0061] In particular, the surface of test pavement 22 can be made of different materials, such as, in a manner not described in detail as easily implemented by a skilled person, an asphalt or cement mix, slabs or stone elements of different shapes, with different levels of regularity and different states of wetting: dry, wet or with surface water veil, frozen, etc. according to specific needs of tire testing campaigns. In addition, in the case of research on innovative materials or new test pavements for road transport infrastructure, test pavement 22 can be equipped with such materials or test pavement surfaces.

[0062] In addition, concentrated obstacles, such as potholes, bumps, sleepers, etc., can be placed on test pavement 22, or on ground 20, again in a nondescript manner easily implemented by a skilled person, to perform tests characterizing the behaviour of vehicle components, e.g., suspensions, under the action of forces resulting from road bumpiness. In this way, test wheel 10 and possible vehicle components are tested under more realistic dynamic conditions than known engineering test benches made by holding a vehicle stationary and stressing the wheels in the vertical direction with actuators.

[0063] Cart 100 can be a gantry frame, with uprights 151 to which transport wheels 110, 120 are mounted. The transport wheels 110, 120 can be four steerable wheels to reduce the machine's drag, which have the main function of transmitting motion to the entire frame 150, to the mechanism 300 that acts as a cantilever suspension for the support 200, and then to head 250 and to any gauging system attached to it.

[0064] Figures 5 to 7 show a possible implementation in which only wheels 120 are driven, by means of a chain drive 111 and gears 112 and 113, connected to two motors 115, for example one for each wheel 120, which provide thrust to the test cart 100, thus enabling it to reach a desired test speed, which can be up to 60 km / h, for example. In a way not shown, all four transport wheels 110, 120 can be driven, with motors 115transmitting the drive torque to all wheels. Single wheels 110, 120, each independently motorized, can also be provided as an alternative not shown.

[0065] Sliding constraints 130, 140 between test cart 100 and guideway 30 are configured to counterbalance test cart 100 relative to guideway 30 during the application of thrust force 320 by thrust actuator 310 and to isolate the application of contact force 220 from ground contact reactions of transport wheels 110, 120.

[0066] As also shown in Figs. 5-7, sliding constraints 130, 140 can comprise eight groups of casters 131 , 141. Specifically, four sliding constraints 130 are arranged horizontally, to compensate for the displacements induced by centrifugal force and to restrain horizontal components of the interaction with the measuring system track. In addition, four sliding constraints 140 are arranged obliquely, to prevent lifting and tilting or the machine from leaving the monorail, to absorb vertical components of the interaction between the test wheel 10 with the test pavement 22, transmitted through the support 200 and mechanism 300 to frame 150, as well as to absorb irregularities of the contact between the transport wheels 110, 120 with the transport track 21 , and minimize disturbances to the various measurements.

[0067] In one possible embodiment, the horizontal sliding constraints 130 can comprise two casters 131 each. The casters 131 can be connected to a shaft 132 by two connecting rods 133 and a support plate 134 integral with the shaft 132. Each shaft 132 can be connected to a respective post 151 of frame 150 with two pins 136 that allow it to rotate about a vertical axis.

[0068] A pair of springs / dampers 135 can be provided to absorb both unavoidable geometric irregularities of the parallelepiped portion 32 of the guideway 30 and to keep the casters 131 in contact with the parallelepiped portion 32 at all times.

[0069] The horizontal-sliding constraints 130 by means of thesuspension system of springs / dampers 135 and the tilting of shaft 132 transmit a trajectory imposed by the guideway 30 to frame 150. In the solution shown of horizontal sliding constraints 130 the tilting of shaft 132 is transmitted by linkage 136 to the steering wheels 110, 120 on which frame 150 rests.

[0070] Thus, the set of casters 131 and linkages 136 steers the transport wheels 110, 120 to follow the guideway 30 substantially eliminating actions that could cause drag. Specifically, in curvilinear sections of guideway 30, the transport wheels 110, 120 steer following guideway 30, eliminating feed resistance due to drift angles of the transport wheels 110, 120 with the transport track 21 .

[0071] In possible implementations, oblique-sliding constraints 140 can comprise a pair of casters 141 connected by a pair of connecting rods 142. A pair of springs / dampers 145 connecting casters 141 and connecting rods 142 to frame 150 can be provided to compensate for various deviations due to geometric imperfections in the guideway 30 and to ensure perfect contact of the casters 141 with it.

[0072] The structure of apparatus 1 according to the invention, e.g., such as the one described above and shown as an example, makes it possible to measure characteristic parameters of tire-to-test pavement interaction with both light vehicle and motorcycle tires and heavy vehicle tires through the acquisition of all the main quantities that characterize the interactions as a whole, such as rolling resistance, noise, lateral force, longitudinal force, self-aligning moment, etc.

[0073] With reference again to Figs. 1 and 2, the head 250 of support 200 can accommodate various sensors 210, not shown in detail as easily implementable by a skilled person, such as load cells, strain-gauges, thermocouples, humidity sensors. The location of the sensors can be chosen to locations other than those shown, as easily implementable by a skilled person.

[0074] Test pavement 22 can also comprise, in a manner not shown as implementable by a skilled person, similar under-pavement sensing for measuring the parameters of the interaction of test tires 15 mounted to test wheel 10 with the test pavement by measuring components in various directions.

[0075] Support 200 is configured to allow various types of measurements of the interaction between tire 15 of test wheel 10 with of test pavement 22. The head 250 can comprise a support plate 255, which is connected to pivot arms 330 and 340, the upper and lower arms of the mechanism 300, respectively, and is also connected to a fork 260 via a hinge 261 that allows controlled rotation of the test wheel 10 by means of a drift actuator 262, which can provide a position signal 273 to the control unit 400, so as to impose a predetermined drift angle.

[0076] The fork 260 in turn is connected to the hub 270 of the test wheel 10 by a hinge 271 , which allows camber angle to be controlled, independently, by a camber actuator 272, which can provide a position signal 273 to the control unit 400.

[0077] Thus, in the structure of apparatus 1 according to the invention, for example as in the exemplifying one described above and illustrated, the main movements necessary to control the characteristic angles of test wheel 10 can be realized by three linear actuators:- a first one, thrust actuator 310, which can provide a position signal 311 to control unit 400, and is installed between frame 150 and lower arm 340 of mechanism 300, can be controlled in force / position by control unit 400, is arranged to adjust the contact force 11 between tire 15 and test pavement 22;- a second one, drift actuator 262, installed between plate 255 and fork 260, controlled in displacement by control unit 400, is arranged to adjust the drift of test wheel 10 and then of test tire 15;- a third one, camber actuator 272, installed between fork 260 and hub270, configured to adjust the camber angle or camber of test wheel 10 and then test tire 15.

[0078] An optical sensor and an inertial sensor can also be mounted to hub270, in a manner not shown as easily implemented by an skilled person, configured to measure, at any instant during testing, the tire drift angle, thus eliminating uncertainties related to the deformation of all elements on the cart, and to perform feedback corrections to compensate for these deformations, using selectively actuators 310, 262, 272.

[0079] Braking systems of wheel 10 can also be mounted to hub 270, in a manner not shown as easily implemented by a skilled person, that can be used to do tests like wheel 10 idle, wheel 10 braked, wheel 10 totally locked, which scrapes on the ground 20 as in a braking, dragged by cart 100.

[0080] Fork 270 can be made in an easily replaceable manner, and it can be made in various configurations, representing or accommodating entire vehicle suspension subsystems, so that structural durability and deformation tests can be carried out under load, obtaining elastokinematics measurements, in a manner not described as easily implementable by a skilled person without further research.

[0081] Compared with prior art measuring test benches and apparatuses, which already allow the determination of longitudinal and lateral force-slip diagrams of car and motorcycle tires, the apparatus according to the invention, as seen in Fig. 2, is configured to position plate 255 at a variety of heights and to allow ample travel to thrust actuator 310, enabling it to accommodate tires of any size, which, depending on their size, can be selectively brought into contact with the ground 20 with desired force and angles of camber and drift for testing.

[0082] In addition, apparatus 1 allows the test pavement 22 to be set up by simulating realistic grip with various types of road test pavement, various grip conditions, and various pavement irregularities.

[0083] Specifically, the apparatus according to the invention allowsmeasurements similar to static test benches such as "four-post rigs" known for characterizing the behaviour of vehicle components, such as suspensions, under the action of ferees resulting from road bumpiness, with the advantage of making such measurements in dynamic situations by setting up the test pavement 22 with various obstacles simulating bumps, potholes, etc.

[0084] The foregoing description of specific embodiments is capable of showing the invention from the conceptual point of view so that others, using the known technique, will be able to modify and / or adapt in various applications such specific embodiment without further research and without departing from the inventive concept, and, therefore, it is understood that such adaptations and modifications will be considered as equivalents of the specific embodiment. The means and materials for realizing the various functions described can be of various kinds without departing from the scope of the invention. It is understood that the expressions or terminology used are for descriptive objects only and therefore not limiting.

Claims

CLAIMS1. An apparatus for measuring performance and contact characteristics between a vehicle test wheel (10) and a ground (20), including:- a motorized test cart (100) configured to move at a predetermined speed along a guideway (30) attached to said ground (20);- a support (200) for the test wheel (10);- a mechanism (300) mounted between said test cart and said support (200) and configured to:- hold said support so that said test wheel (10) can roll on said ground (20) with the movement of said test cart along said guideway (30); and- allow a movement of said support (200) relative to said ground (20) so that said test wheel (10) can be raised relative to said ground (20) or lowered until it contacts said ground (20);- a thrust actuator (310) configured to apply a thrust force (320) between said test cart (100) and said support (200) and cause said support (200) to move toward said ground (20) through said mechanism (300) and to keep said test wheel (10) in contact with said ground (20) so that said wheel exerts a contact force (220) against said ground (20); characterized in that- said mechanism (300) is mounted between said test cart (100) and said support (200) so that said support (200) is cantilevered from said test cart (100) and said test wheel (10) is arranged outside laterally from said test cart (100);- said test cart (100) comprises transport wheels (110,120) which are mounted to make direct contact with said ground without making contact with the guideway (30) and on which said test cart (100) rests;said test cart comprises a plurality of sliding constraints (130,140) between said test cart (100) and the guideway (30) configured to counterbalance said test cart (100) relative to the guideway (30) during the application of said thrust force (320) by the thrust actuator (310) and to isolate said contact force (11 ) from contact reactions of said ground with said transport wheels (110,120).

2. The apparatus according to claim 1 , wherein at least one pair of wheels (110) of said transport wheels (110, 120) consists of driving wheels, and at least one pair of wheels (120) of said transport wheels (110,120) is a pair of steering wheels.

3. The apparatus according to claim 1 , wherein said support (200) comprises at least one force sensor (210) between said test wheel (10) and said support (200), configured to provide a force signal proportional to the contact force (11 ).

4. The apparatus according to claim 1 , wherein there is provided a control unit (400) connected with said thrust actuator (310) and said sensor (210), said control unit (400) being configured to modify said thrust force (320) exerted by said thrust actuator (310) according to the force signal provided by said force sensor (210) so that said contact force (11 ) maintains a predetermined value with said proceeding of said test cart (100) along said guideway (30).

5. The apparatus according to claim 1 , wherein said test cart (100) is a gantry frame (150), with uprights (151 ) to which transport wheels (110, 120) are mounted.

6. The apparatus according to claim 1 , wherein said sliding constraints (130, 140) between said test cart (100) and said guideway (30) comprise caster assemblies (131 ,141 ) configured to slide on said guideway and comprise: horizontal caster assemblies (130), configured to make contact on said guideway by rotating in horizontal planes, and are configured to compensate for centrifugal force induceddisplacements and to hold up horizontal components of the interaction of said test wheel with the ground (20);- oblique caster assemblies (140) that are configured to contact said guideway by rotating in planes oblique to said ground (20) to prevent a lifting or tilting of said test cart and to absorb vertical components of the interaction of said test wheel (10) with said ground transmitted to said test cart through said support (200) and said mechanism (300).

7. The apparatus according to claim 6, wherein said horizontal caster assemblies (130) and said oblique caster assemblies (140) comprise springs / dampers (135, 145) arranged to absorb geometric irregularities of said guideway (30) and to maintain rolling contact with it.

8. The apparatus according to claim 6, wherein said horizontal caster assemblies (130) comprise two caster assemblies (131 ), arranged to contact on said guideway by rotating in horizontal planes, wherein said caster assemblies are connected to a shaft (132) by means of two connecting rods (133) and a support plate (134) integral with the shaft (132), each shaft (132) being connected to said frame (150) by pins (136) enabling it said rotation about a vertical axis.

9. The apparatus according to claim 7, wherein in said horizontal wheel assemblies (130) there is provided a linkage (136) connected to said shaft (132) and connected to a steering hub of said wheels (110, 120) on which said frame (150) rests.

10. The apparatus according to claim 6, wherein said oblique sliding constraints (140) comprise a pair of casters (141 ) connected by a pair of connecting rods (142).

11. The apparatus according to claim 1 , wherein said support (200) comprises sensors for measurement of the interaction between tire (15) of said test wheel (10) with said ground (20).

12. The apparatus according to claim 1 , wherein said support (200)comprises a support plate (255) that is connected to upper and lower articulating arms (330, 340), respectively, of said mechanism (300)13. The apparatus according to claim 1 , wherein said support (200) comprises a fork (260) pivotally connected to said support (200), a drift actuator (262) being provided to cause a controlled rotation of said test wheel (10) so as to impose a predetermined angle of drift.

14. The apparatus according to claim 1 , wherein said support (200) comprises a fork (260) connected to a hub (270) of said test wheel (10) by means of a hinge (271 ), a camber actuator (272) configured to arrange said test wheel (10) according to predetermined camber angles being provided.

15. A system comprising a guideway (30) and further comprising an apparatus according to the preceding claims, wherein said guideway (30) is a reinforced concrete monorail having a root (31 ) anchored to said ground (20), from said root (31 ) extending a central parallelepiped portion (32) and an upper portion (33), said central parallelepiped portion (32) and said upper portion (33) being configured to engage said sliding constraints (130,140) of said cart.

16. The system according to claim 15, further comprising said ground (20) configured to define adjacent said guideway a transport track (21 ) for said transport wheels (110,120), and a test pavement (22) for said test wheel (10).

17. The system according to claim 16, in which said guideway (30) is arranged on said ground (20) to form a closed flat path with straight stretches (35) and curvilinear stretches (36).

18. The system according to claim 16, in which said ground test pavement comprises concentrated obstacles, such as potholes, bumps, sleepers, etc., configured to perform tests to characterize the behaviour of vehicle components, such as suspensions.

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