DESCRIPTION

The present invention relates to the field of apparatus for testing the braking force and braking efficiency of light vehicles, and in particular relates to an improved plate brake tester.

The invention relates also to a method for manufacturing such an improved structure of brake tester.

Description of the prior art

As known, a brake test bench is an apparatus for measuring the braking force, the braking efficiency, and if necessary, other parameters of the vehicles of different type. The test benches are nowadays widespread in mechanical workshops and in review centres specialized in carry out the tests necessary for the mandatory periodic inspection of vehicles circulating on the roads.

The brake test benches are essentially of two different types and precisely roller brake tester and plate, or platform, brake tester.

A roller brake tester provides a support structure, commonly installed inside a hollow made in the floor. The support structure provides two couples of rollers pivotally mounted about parallel axes. The two couples of rollers are positioned at symmetric positions with respect to a plane orthogonal to the above mentioned rotational axes and protrude from the upper side of the structure through suitable apertures. These are spaced one with respect to the other due to the presence of a central zone defining a space within which the devices for operating the rollers are typically positioned. The vehicle to be tested is positioned with a couple of wheels of the same axis at the apertures, in such a way that the tyre of the wheels is arranged in creep contact with a respective couple of rollers. By a moving system, a rotation of the rollers at a determined speed is caused, and, therefore, a rotation of the wheels. In these operative conditions the braking system is operated in order to measure the typical parameters of the braking system, in particular the braking force, the braking efficiency and the weight of the vehicle.

Furthermore, the roller brake tester, even though it is able to simulate conditions similar to those that occur when the vehicle is braking on road, is not able to reproduce very accurately the dynamics that occur in real conditions .

The above mentioned drawbacks have been partially overcome by using the plate, or platform, brake tester. In this case, the vehicle to be tested is advanced at a speed of about 10 km/hr at the area where the plate is installed. When the wheels of the vehicle are positioned at the plates, the braking system is operated. The braking force is, therefore, measured at the same time of the mass, or better the weight, of each wheel, and, in case, of other parameters of the vehicle, by means of detection devices, for example one, or more load cells, positioned below the plate, or one, or more, force sensor. The data are, then, processed in order to determine the main parameters and obtain the curves of interest, as for example, the curve of load and of braking force vs. time.

The plate, or platform, brake tester currently on the market provides a metallic net, or a knurled metallic plate, as the surface on which the braking test is carried out .

However, the above described types of plates have many drawbacks, in particular a reduced adherence has been found in case of wet wheels, or impregnated with snow, or mud, with consequent measurement errors and the risk of endangering the safety of the operator who follows the test, or to cause the damage of the vehicle subjected to the test.

The above described drawbacks have been, at least in part, overcome by a third type of vehicles plate brake tester providing a covering layer applied to a face of a support structure. More precisely, the covering layer is constituted by at least a layer of resin having a predetermined thickness, in which granules of an abrasive material, commonly corundum, are embedded. Lo strato of rivestimento finale risulta provvisto of una superficie ad elevato attrito.

However, this last type of plate brake tester, while overcoming the above drawbacks of the other types of plate brake tester, is obtained by a production process providing a succession of operations which requires long times to be completed as well as imply significant costs.

Plate brake tester having the above described drawbacks, for example, in US5230242, EP1199540, and US2664745.

Summary of the invention

It is therefore an object of the present invention to provide a brake tester for vehicles which allows to overcome the above mentioned drawbacks of plate brake tester of prior art.

It is in particular an object of the present invention to provide a brake tester that is easy to manufacture and economically advantageous with respect to the plate brake tester of prior art, but that is, at the same time, able to guarantee a correct measurement of the vehicle braking force .

It is another object of the present invention to provide a brake tester that is able to assure that the test is carried out in conditions of absolute safety and therefore to guarantee the safety of the operator who carried out the test, and avoiding the possibility of damage to the vehicle.

These and other objects are achieved by the brake tester for a vehicle, according to the present invention, comprising :

- a support structure;

- at least a measurement plate mounted on said support structure, said, or each, measurement plate being arranged to be crossed by at least a wheel of said vehicle, during a brake test;

- a measurement unit configured to measure the vertical and/or horizontal forces acting on the, or each, measurement plate and to convert them into values indicative of the efficiency of the vehicle braking system;

whose main characteristic is that said, or each, measurement plate is a plate comprising a base surface from which a plurality of protuberances protrudes provided of a through hole arranged according to a predetermined pattern, said protuberances being configured in such a way to define at their top a support plane for the wheels of said vehicle during a brake test.

Other characteristics of the invention are set out in the dependent claims.

Preferably, the aforementioned protuberances have all the same height h from the base surface.

Advantageously, the height h of each protuberance of said plurality is comprised between 2 mm and 8 mm, preferably comprised between 3 mm and 6 mm, for example equal to 5 mm.

In a possible embodiment of the invention, each protuberance of the aforementioned plurality is obtained by subjecting a metallic plate of predetermined thickness to a punching step.

Preferably, each protuberance can have a substantially circular, or substantially elliptic cross section.

Alternatively, the cross section of each protuberance can be polygonal-shaped.

Preferably, the upper edge of each perforated protuberance is a "sharp corner" in such a way to produce a high friction force on the wheels of the vehicle subjected to a test.

Advantageously, the measurement unit comprises at least a detection device configured to measure the horizontal and/or vertical forces acting on the measurement plate during the test carried out on the vehicle .

In particular, the measurement unit can comprise:

- at least a first detection device arranged to detect the vertical forces P acting on the measurement plate during the test; and

- at least a second detection device arranged to detect the horizontal forces F acting on the measurement plate during the test.

In a possible alternative embodiment of the invention, the measurement unit can comprise at least a detection device of biaxial type arranged to detect both the horizontal forces F and the vertical forces P acting on said measurement plate during said test.

In particular, each measurement plate can be substantially rectangular shaped. For example each measurement plate can have a length 1 comprised between about 1000 and 2000 mm, and a width L comprised between about 650 and 1000 mm.

Advantageously the brake tester can have a total length ltot comprised between about 4000 and 6000 mm, and a total width Ltot comprised between 2000 and 2400 mm.

According to another aspect of the invention, a method for manufacturing an improved structure of brake tester for a vehicle comprises the steps of:

- disposing a support structure;

- positioning a measurement plate above said support structure ;

- disposing a measurement unit configured to measure the forces acting on said measurement plate;

whose main characteristic is that said measurement plate is obtained by subjecting a plate, in particular a plate made of metallic material, having a predetermined thickness, to a punching step in such a way to make a plurality of protuberances arranged according to a predetermined pattern and provided of a through hole, said protuberances having the same height in such a way to define, at their top, a support plane g for the wheels of said vehicle during a brake test.

Brief description of the drawings

The invention will now be shown with the following description of its exemplary embodiments, exemplifying but not limitative, with reference to the attached drawings in which :

— Fig.l diagrammatically shows a lateral view of a plate brake tester, according to the invention, in working conditions;

— Fig.2 shows in detail a section view of an enlargement of a portion of the brake tester of figure 1 along a longitudinal section;

— Fig.3 shows a perspective view from above of a possible embodiment of a brake plate tester according to the invention;

— Fig.4 shows an enlargement of a portion of the brake tester of figure 3;

— Figures 5A and 5B show an enlargement of a perspective view of two possible alternative embodiments of the measurement plate that can be used to manufacture the brake tester of figure 3;

— Figures from 6A to 6C are diagrammatically shown in cross section view some possible embodiments of the protuberances made on the measurement plates for the brake tester according to the invention;

Fig.7 diagrammatically shows a front view of another alternative embodiment of the brake tester according to the invention;

— Fig.8 shows an axial section of a single protuberance of which each measurement plate of brake tester of figure 7 can be provided of;

— Figures from 9 to 12 diagrammatically show a possible succession of steps through which is possible to obtain the brake tester according to the present invention;

— Fig.13 diagrammatically shows a possible coupling provided by the present invention to engage the measurement plate to the support structure.

Detailed description of some exemplary embodiments of the invention

As diagrammatically shown in figure 1, a brake tester 100 for a vehicle 50, according to the invention, comprises a support structure 10, on which at least a measurement plate 30 is mounted. More in detail, the, or each, measurement plate 30 is arranged, during a brake test, to be crossed by at least a wheel 51 of the tested vehicle 50. A measurement unit 300 is, furthermore, provided associated to the, or each, measurement plate 30 and configured to measure the vertical and/or horizontal forces acting on the support surface of the, or each, measurement plate during the aforementioned measuring test and to convert them into values indicative of the efficiency of the vehicle braking system. The measurement unit 300 provides, in particular, at least a detection unit comprising at least a detection device 60 arranged to detect the horizontal and/or vertical forces acting on the, or each, measurement plate 30 during a test. The, or each, detection device 60, for example a load cell, is advantageously positioned below the measurement plate 30. The data detected by the detection devices 60 are, then, sent to a processing unit 300, which provides to process the detected data in such a way to determine the vehicle braking force 50 and the weight profile as a function of time. According to the invention, the, or each, measurement plate 30 is constituted of a plate 40, advantageously made of metallic material, having a base surface 31 from which a plurality of protuberances arranged according to a predetermined pattern on plate 40 protrudes 35. More in particular, the protuberances 35 provide respective through holes 38 and are configured in such a way to define, at their top 36, a support plane g on which the wheels 51 of vehicle 50 rest during a brake test. In particular, all the above protuberances 35 have the same height (h) .

The measurement plate 30, according to the invention, is easier to be produced than other solutions of prior art, and has, at the same time, a high friction. Furthermore, the holes allow to avoid that any raindrops present on the wheels of the vehicle subjected to the test can be transferred to the surface of the, or each, measurement plate 30 making it slippery.

As shown in detail in figure 5B, each protuberance 35 of the aforementioned plurality can have a height comprised between 2 and 8 mm, preferably comprised between 3 and 6 mm, for example a height equal to 5 mm. In particular, each protuberance can be substantially cylindrical-shaped (figure 5A) , or substantially conical- shaped (figure 5B) .

In a possible embodiment of the invention, as described in detail in the following, the protuberances 35 can be made by subjecting a metallic plate 40 having a predetermined thickness to a punching step.

As diagrammatically shown, as an example, in figure 6A, the cross section of each protuberance 35 can be substantially circular-shaped. In a possible alternative embodiment shown in figure 6B, instead, the cross section of each protuberance 35 can be substantially elliptical shaped, but the possibility is not excluded that the protuberances 35 can have a cross section of different shape, for example a polygonal shape, in particular a square (figure 6C) , rectangular, hexagonal, shape etc. In particular, the thickness of each protuberance can be comprised between 2 mm and 5 mm, for example can be equal to about 3 mm.

In figure 8 a particular embodiment of the invention is shown, in which the upper edge 37 of each perforated protuberance is a "sharp corner" in such a way to produce a high friction force on the wheels, or tyre, 51 of vehicle 50 subjected to a test.

As shown for example in figure 4, the perforated protuberances 35 can be distributed on the measurement plate 30 organized in a predetermined number of rows ri, with i comprised between 1 and a predetermined number n, and, in case, staggered as it is shown in figure 4. In particular, a measurement plate 30 can provide a predetermined number of protuberances 35 for each m ² , for example a number of protuberances comprised between 1000 and 3000 for each m ² , in particular depending on the geometry of the plates and/or the shape chosen for the protuberances. Advantageously, in the case of protuberances having cylindrical, or frusto-conical , shape, a number of protuberances comprised between 1500 and 2500 for each m ² can be provided, preferably a number of protuberances comprised between 2000 and 2600 for each m ² , for example comprised between 2200 and 2500 protuberances for each m ² .

According to another aspect of the invention the, or each, measurement plate 30 is engaged to the support structure 10 by means of engagement elements 130 of removable type (figures 12 and 13) . For example, the support plate 30 can be engaged to the support structure 10 by means of a bolt connection. In this way, the measurement plate 30 can be fixed to the support structure 10 in order to carry out a determined number of tests and then can be easily and quickly replaced by a new one, or however temporarily removed, to inspect the various components composing the brake tester 100.

As shown for example in figure 3, each measurement plate 30 can be substantially rectangular-shaped and have a length 1 comprised between about 1000 mm and about 2000 mm and a width L comprised between about 650 mm and about 1000 mm. More in detail, the improved structure of brake tester 100 for a vehicle 50 can comprise at least a first measurement plate 30a which, in use, is crossed by at least a wheel 51a of a first side of the vehicle 50 and at least a second measurement plate 30b positioned at a distance d comprised between about 100 mm and about 800 mm, for example between about 200 mm and about 600 mm, from the first measurement plate 30a and crossed, in use, by at least a second wheel 51b of a second side of the vehicle 50.

Still with reference to the embodiment of figure 3, the brake tester 100 can comprise 4 measurement plates 30a-30d, each of which provided of a plurality of protuberances 35 as above described. More precisely, at each plate 30a-30d data relating to braking force and braking efficiency are detected at a corresponding wheel 51a-51d of the vehicle 50.

In the figures from 9 to 13 the main steps are diagrammatically shown of the method, according to the invention, for manufacturing a brake tester 100 for a vehicle 50. More in detail, the manufacturing method provides to subject a plate 40 of a predetermined thickness to a punching step using a punching device 250. In particular, the punching device 250 is movable from/towards the plate 40 and is configured in such a way to exert a predetermined pressure on a surface 32 opposite to a base surface 31. More in particular, the punching device 250 can be configured as diagrammatically shown in figure 9 to make a protuberance 35 at a time on a metallic plate 150 of predetermined thickness. Alternatively, according to an alternative embodiment, not shown in detail for reasons of simplicity, the punching device 250 can be configured to make on the metallic plate 150 a predetermined number n of protuberances 35 at each step, for example all the protuberances of the measurement plate 30 at once. In general, therefore, the punching device 250 can be configured to make on the metallic plate 150 a predetermined number n at a time, with n=l..A, where A is the total number of protuberances of the measurement plate 30. In this way, a plurality of protuberances 35 is made protruding from the surface 31, having the same height h and provided of the aforementioned through holes 38. More in detail, the aforementioned protuberances 35 are made on the plate 40 according to a predetermined drawing, or pattern. Once the punching step of plate 40 is finished a measurement plate 30 is obtained (figure 10) . This is positioned on a support structure 10, already provided of a predetermined number of detection devices 60, for example of biaxial type, and the relative wiring for the connection to a measurement unit 300 (figure 11) . Finally the measurement plate 30 is fixed to the support structure 10 by welding, or, according to an alternative embodiment of the invention and diagrammatically shown in the figures 12 and 13, by means of a series of engagement elements of removable type 130, for example owing to a predetermined number of bolts.

In a particular alternative embodiment of the invention not shown in figure for reasons of simplicity, furthermore, the brake tester 100 obtained as above described with reference to the figures from 1 to 13, can be installed at a lifting platform, as for example described in WO2015097651 in the name of the same Applicant .

The foregoing description exemplary embodiments of the invention will so fully reveal the invention according to the conceptual point of view, so that others, by applying current knowledge, will be able to modify and/or adapt for various applications such embodiment without further research and without parting from the invention, and, accordingly, it is therefore to be understood that such adaptations and modifications will have to be considered as equivalent to the specific embodiments. The means and the materials to realize the different functions described herein could have a different nature without, for this reason, departing from the field of the invention. It is to be understood that the phraseology or terminology that is employed herein is for the purpose of description and not of limitation .