FR3067462B1 - DEVICE FOR MEASURING THE RESISTANCE TO THE ARREST OF A SPORTS LAWN - Google Patents

Abstract

The invention relates to a device (1) for measuring the pull-out resistance of a sporting lawn, comprising a platform (2) having an upper surface (2a) sized to form a ballast laying surface, a penetration bar (5), mounting means (3, 4) which are connected to the platform (2) and configured to connect the bar (5) to the platform (2) in a movable manner. vertical translation and pivoting about a horizontal axis, so that the bar (5) can be partially driven into the sporting lawn and then rotated, means (6) for actuating the bar (5) configured to apply thereto a rotational torque to rotate it after it has been partially depressed into the sporty lawn, and means (6) for measuring the torque applied to the bar (5) to rotate it.

Description

DEVICE FOR MEASURING THE RESISTANCE TO THE ARREST OF A

SPORTS LAWN

The present invention relates to the field of mechanical characterization of lawns and relates in particular to a device for measuring the tear resistance of a lawn, in particular a sporting lawn such as that of a football field , rugby or golf, or that of an equestrian track. The instability of sports lawns is one of the problems that recurrently meet the owners of sports enclosures. The practice of sports such as football, rugby, golf or hippism, involves significant horizontal forces, especially during scrums for rugby, which can damage very quickly and very strongly turf and also cause a shearing of the foundation and turf roots, which may lead to a decrease in turf cover and undulations on the lawn surface. Moreover, it is easy to understand that a lawn in perfect condition promotes the quality of the game played, football being the first example.

In order to solve this problem and improve lawn stability, and thus their durability, new hybrid lawn structures have been developed. These hybrid structures generally involve soil strengthening or a combination of natural turf and artificial turf. It has also been proposed, for clay lawn structures, the use of sand to improve drainage and reduce the moisture sensitivity of the lawn structure.

However, it is important to be able to correctly characterize the behavior of natural grass lawn structures, for example in order to identify the structures offering the most stability. This behavior can be characterized by a variety of conventional mechanical test methods such as the Clegg compactometer impact test to measure surface hardness, or the rotary tensile test to measure spike shoe stability. lawn surface.

For the measurement of the penetration resistance and the shear strength, there has been proposed a device called "GoingStick", designated GS device in the following description, described in European Patent EP 1 348 114 B1.

The GS has been developed to reliably and consistently determine the condition of a race track ("going"), to indicate to interested parties whether the terrain is light, flexible, sticky, heavy, etc.

A conventional pre-GS method for determining the condition of a horse track was based on the use of a penetrometer composed of a simple metal rod and weighing one kilogram: the weight is dropped. of a determined height then one notes the depth to which it penetrated in the ground. It will be readily understood that this conventional method does not make it possible to measure the resistance to tearing.

The device GS is a portable device comprising an elongate handle which carries at the top a signal processing and display unit and which is connected at its lower end to a sleeve-like member having a cylindrical tubular portion terminating at its free end by a flange forming a support plate on the ground, and a measuring unit which is located inside the tubular portion of the sleeve and is connected at its upper end to the handle and at its level. lower end to a pointed tooth which protrudes from the flange. The measuring unit is formed by a machined metal beam whose central portion has a square cross-section and thus comprises two pairs of faces, a first pair of faces carrying four strain gauges, two on each face, mounted so as to measuring the shear to which the central part is subjected, while the other pair of faces carries four strain gauges, two on each face, mounted so as to measure the compressive forces experienced by the central part during the penetration into the ground.

In use, the user holds the handle vertically and pushes it into the ground until the flange bears against the surface of the ground. In this position, the tooth is sunk into the soil at a known depth. Then, in a first phase, the user applies on the handle a vertical load which is transmitted directly to the flange. The tooth then experiences forces as it is forced deeper into the ground, and these forces are measured by the strain gauges that communicate the measurement data to the signal processing and display unit. . Then, in a second phase, the user pushes the handle, at its upper end, forwards or backwards, thereby rotating the device around an edge of the flange. The tooth transmits shear forces, associated with the pivoting movement, to the measurement unit, where the shear forces are measured by the strain gauges. Again, the measurement data is communicated to the signal processing and display unit. The measurement data from the first and second phases are analyzed in the signal processing and display unit according to a particular algorithm to derive a measure of the state of the terrain which is displayed on the display screen of said unit.

In practice, it appears that the measurement of the penetration resistance using the GS device varies depending on the types of lawn structure and their state, suggesting that the GS device is a useful tool to characterize the resistance to penetration of a given lawn. It also appears that the measurement of the shear strength varies rather little according to the types of lawn structure, although in practice there are qualitatively differences in the behavior and in particular in the resistance to tearing. Therefore, it appears that the measurement made by the GS device is not a measure faithful to the normal conditions of use of the lawns, and thus does not give, strictly speaking, a measure of the tear resistance.

The object of the present invention is therefore to provide a device for measuring the tear resistance of a sports lawn.

The solution according to the present invention is based on the fact that in use the sportsmen, or horses in the case of horse tracks, also exert on the lawn, by their weight, a static compressive stress which influences the behavior of the lawn, and that the measuring device must thus allow the application of such a static compressive stress during the measurement, and this in a manner easy to implement by the user and with a simple structure and reliable and whose manufacture and maintenance are less expensive.

The present invention thus relates to a device for measuring the resistance to tearing of a sports lawn, characterized in that it comprises: - a platform having a lower surface intended to come into contact with the surface sports lawn, and an upper surface opposed to the lower surface and sized to form a ballast placement surface; - a bar penetration intended to be partially embedded in the sports lawn; - mounting means which are connected to the platform and configured to connect the penetration bar to the platform in a vertically translatable and pivotable manner about a horizontal axis, so that the bar penetration can be partially embedded in the sporty lawn and then pivoted; penetrator bar actuation means which are configured to allow a torque to be applied to the penetration bar in order to rotate it after it has been partially inserted into the sporting lawn; and - torque measurement means applied to the penetration bar to rotate it after it has been driven into the sporting lawn.

Thus, in use, the user can place a ballast on the platform so that it will apply on the sports lawn a static compressive stress while the penetration bar is rotated and that the torque required for its pivoting is measured.

According to the present invention, the upper surface of the platform may allow the user to stand on it, so that the ballast will simply be the weight of the user.

Alternatively, the device according to the present invention may also comprise a weight, formed by one or more bodies sized to be able to be placed on the upper surface of the platform, the upper surface of the platform being, preferably , flat. The advantage of predicting this type of ballast is that it is possible to choose precisely the static compressive stress that is applied to the sporting lawn, since it will be sufficient to choose, depending on their weight, the body or bodies to be laid on the platform. This avoids any measurement variations that may result from users of different body sizes.

Preferably, the platform is formed by a parallelepiped plate in which is formed an elongated slot, the mounting means being configured to connect the penetration bar to the platform in a position such that the penetration bar is adapted to be partially embedded in the sporty lawn as it passes through the light, the light allowing the subsequent pivoting of the penetration bar.

Preferably, the longitudinal axis of the light coincides with one of the two mediators of the platform, the upper surface of the platform having two surface regions, on either side of the light, on which a ballast can be laid. Such a configuration makes it possible to provide a ballast symmetrically on each side of the penetration bar, so as to obtain a static compressive stress of the sporting lawn which is more uniform in the region where the penetration bar is pressed.

Preferably, the mounting means comprise two bearings between which is mounted rotatably a shaft whose longitudinal axis is horizontal, where appropriate with a bearing on each side of the slot and the longitudinal axis of the shaft orthogonal to the longitudinal axis of the light, the shaft further comprising a through hole adapted to be traversed by the penetration bar and the mounting means further comprising means for stopping in translation of the penetration bar relative to 1 '; tree.

Preferably, the penetration bar comprises at least one through hole perpendicular to the longitudinal axis of the penetration bar, the at least one through hole being adapted to be traversed by an elongated member then projecting out of said through hole so as to serve as translation stop while abutting against the shaft, the through hole and the elongated member forming said stop means.

Preferably, the device according to the present invention comprises means for adjusting the maximum depth at which the penetration bar can be driven into the sporting lawn, the adjustment means being preferably formed by a series of through holes perpendicular to the longitudinal axis of the penetration bar and regularly distributed along the latter, each through hole being adapted to be traversed by an elongated member then projecting out of said through hole so as to stop in translation while abutting against the tree.

The actuating means may for example be formed by the upper end region of the penetration bar, which will constitute a gripping region by which the user can directly apply a torque to the penetration bar. The means for measuring the torque applied may be any suitable means, such as those described in European Patent EP 1 348 114 B1.

Preferably, the means for actuating the penetration bar and the means for measuring the torque applied to the bar are formed by a torque wrench whose head is connected to means for transforming the pivoting movement of the torque wrench. around his head in a pivoting motion of the penetration bar.

Preferably, the means for transforming the pivoting movement of the torque wrench around its head into a pivoting movement of the penetration bar comprises the shaft of the mounting means, which shaft has an end region which projects out of a respective bearing and which has means of coupling to the head of the torque wrench, so that a pivoting of the latter results in a rotational movement of the shaft and therefore in a pivoting movement of the penetration bar.

The penetration bar may be provided at the top with a handle, preferably a handle formed by two rigid straight portions which extend perpendicularly to the penetration bar, on each side thereof, and are aligned with each other. with each other, in order to improve grip of the penetration bar when it sinks into the sporting lawn.

To better illustrate the object of the present invention, a particular embodiment will be described below, by way of indication and not limitation, with reference to the appended drawing.

In this drawing: - Figure 1 is a perspective view from above according to a particular embodiment of the present invention; - Figures 2 and 3 are respectively side and front views of the device of Figure 1; Figure 4 is a bottom perspective view of the device of Figure 1; - Figure 5 is a side view of the device of the

Figure 1 in use; and - Figure 6 is a side view of the device of the

Figure 1 in the final position of use.

The structure of the pull-out measuring device 1 according to a particular embodiment will first be described, with reference to FIGS. 1 to 4. In these figures, it can be seen that the device 1 comprises a generally a platform 2, two bearings 3, a rotary shaft 4, a penetration bar 5 and a torque wrench 6.

The platform 2 is in the form of a rectangular plate, which thus comprises an upper face 2a and a lower face 2b. An elongate lumen, the function of which will be explained below, is provided in the center of the platform 2 and extends perpendicularly to the longitudinal axis of the platform 2. On each side of the light 20 are made two threaded through holes 21 which will be used for fixing a respective bearing 3. Four threaded through holes are also made in the region of each corner of the platform 2, and in each of these through holes is screwed a bolt member 22 until its head 22a abuts the upper surface. 2a of the platform 2, the member 22 being dimensioned so that its rod 22b protrudes from the lower surface 2b of the platform 2 and thus forms a foot, also designated by the reference numeral 22b.

The platform 2 is sized to allow conveniently placing a ballast, which may be the user himself or one or more heavy bodies. For example, the platform 2 may have a width of at least 20 cm and a length of at least 20 cm, and preferably a width of at least 40 cm and a length of at least 50 cm.

The bearings 3 are conventional bearings, and may consist of flanged bearings as illustrated in FIGS. 1 to 3. The bearings 3 thus comprise a central body 30 which receives a ball bearing (not shown) and a flange 31 which extends on each side to the base of the body 30 and which comprises two through holes, one on each side of the body 30. The bearings 3 are dimensioned so that, when the flanges 31 are applied against the upper surface 2a of the platform 2, the two through holes of each flange 31 are aligned with the two through holes 21 located on the same side of the slot 20, so that each bearing 3 can be fixed to the platform 2 by fasteners 32 screwed each in a through hole of a flange 31 and in the respective through hole 21.

After the bearings 3 are fixed to the platform 2, they are facing each other and their ball bearings are at the same height, so as to allow the rotational mounting of the shaft 4 between the two Bearings 3. The shaft 4 comprises a central body 41 having two ends from each of which extends a cylindrical seat 42 rotatably mounted in the ball bearing of the respective bearing 3. The shaft 4 is thus rotatably mounted about its longitudinal axis. More specifically, the central body 41 has a cross section that is oblong, so that the central body 41 has two flat faces 43. The shaft 4 is mounted in the bearings 3 so that in the initial position, that is to say say before a rotational movement is printed on the shaft 4, the flat faces 43 are horizontal. Thus, in the initial position, one of the plane faces 43 is oriented upwards, opposite the platform 2, while the other is oriented downwards, in the direction of the platform 2.

Furthermore, the central body 41 comprises at its center, defined in the longitudinal direction of the central body 41, a through hole 44, whose function will be explained below, which is made for example by drilling and which is perpendicular to the flat faces. 43. In the initial position, the through hole 44 is opposite the light 20, above it.

Finally, one of the cylindrical bearing surfaces 42 is dimensioned to extend beyond its respective bearing 3, which comprises for this purpose a through hole in its body 30, and the free end of this cylindrical seat 42 has a housing of polygonal section, for example square, whose function will be explained below.

The penetration bar 5 has the same cross section as the through hole 44 of the shaft 4, and is dimensioned to slide in the through hole 44 being guided in translation by the latter. The penetration bar 5 is further dimensioned to extend both above the shaft 4 and below the platform 2 through the light 20, which will be dimensioned to allow the passage of the penetration bar 5. The upper end region of the penetration bar 5, above the shaft 4, is designated by the reference numeral 5a while the lower end region, below the platform 2, is designated by the reference numeral 5b.

The penetration bar 5 further comprises a series of through holes 50 made, for example by drilling, at regular intervals along the penetration bar 5, perpendicular to the longitudinal axis of the latter and passing through its center. These through holes 50 are dimensioned so that an elongate member 51, for example a bolt, can be introduced through any of the through holes 50 and protrude on either side thereof. The elongate member 51 thus serves as a stop in translation downwardly of the penetration bar 5, the elongated member 51 abutting against the flat face 43 facing upwards. It will be readily understood that providing a series of through holes 50 spaced equidistantly from each other makes it possible to adjust the distance over which the lower end region 5b of the penetration bar 5 protrudes with respect to the lower surface 2a of the platform 2, and therefore the depth to which it will be introduced into the sports surface 7 (Figures 5 and 6).

In order to facilitate the manipulation of the penetration bar 5, a handle 52 is provided at the upper end of the penetration bar 5. The handle 52 is formed of two rigid straight portions 52a aligned on the same axis and extending orthogonally to the longitudinal axis of the penetration bar 5. The lower end of the penetration bar 5 is advantageously rounded or pointed, to facilitate penetration into the athletic lawn 7.

Finally, the torque wrench 6 is a conventional torque wrench, shown schematically in the figures, generally comprising a handle 60 by which it can be actuated by a user, and a head 61 from which a part extends. male 62 whose cross section and dimensions correspond to those of the housing of polygonal section of the free end of the cylindrical bearing surface 42 of the shaft 4. The torque wrench 6 can thus be mounted, by its head 61, on the shaft 4, so that a user can, by rotating the torque wrench 6 about the axis of rotation of the shaft 4, rotate the shaft 4 about its axis of rotation and therefore rotate the penetration bar 5 in a pivoting movement whose pivot point is at the center of the through hole 44 of the shaft 4.

The torque wrench 6 is configured to measure the torque it applies to the shaft 4, and therefore the one applied thereto by the user. In the embodiment illustrated in the figures, the torque wrench 6 comprises a display device 63 by which the torque measurement value is displayed in real time (FIG. 6). The technology to obtain this measurement is known and will not be described in detail here.

The principle of measuring the pull-out resistance of a sports surface 7 with the device 1 will now be described with reference to FIGS. 2, 3, 5 and 6.

Referring firstly to FIG. 2, it can be seen that device 1 is shown in side view in the initial position: the platform 2 is placed on the sporting lawn 7 (FIG. not shown in Figure 2), with the lower face 2b against the surface of the sporting lawn 7. The feet 22 also engage in the sporting lawn 7 to maintain the position of the platform 2 during the measurement. The elongated member 51 is placed in one of the through-holes 50, chosen according to the depth at which it is desired for the penetration bar 5 to enter the sporting lawn 7, and then the penetration bar 5 is introduced into the hole through 44 of the shaft 4 to be stopped in its downward movement by the abutment of the elongated member 51 against the shaft 4. It is recalled that in this initial position the flat faces 43 of the shaft 4 are horizontal, so that the penetration bar 5 is vertical. The user can then stand on the platform 2, with both feet resting on the regions of the upper surface 2a of the platform 2 which is located between a bearing 3 and the respective edge of the platform. form 2, or put heavy bodies (not shown), such as known weight blocks, on these same regions of the upper surface 2a. In both cases, a weighting of the platform 2 is obtained so that the latter applies a static compressive stress on the sporting lawn 7 throughout the measurement.

Of course, it will be possible to define the weight of the ballast applied on the platform 2 according to parameters chosen by the user, such as the type of sport practiced on the sports lawn.

After the platform 2 has been weighted, the user mounts the torque wrench 6 on the cylindrical seat 42 of the shaft 4, engaging the male part 62 in the corresponding housing. The housing is configured such that, in the initial position, the torque wrench 6 is horizontal after it has been coupled to the shaft 4.

It is then sufficient for the user to rotate the torque wrench 6 upwards, as shown in Figure 5, so as to rotate the penetration bar 5. The torque wrench 6 will then measure the effort exerted by the user to pivot the penetration bar 5 while its lower end region 5b is sunk into the sporting lawn 7.

It is thus possible to deduce the shear strength of the sporting lawn 7 in a similar manner to the GS device of the prior art, with the difference that the pivoting of the penetration bar 5 is carried out while the sporting lawn 7 is subjected to a static stress of compression.

This gives a real measure of the resistance to tearing of the sporting lawn 7, and this in a manner faithful to the normal conditions of use of the sporting lawn 7.

It will be possible to establish different measurement protocols, at the choice of the user. For example, it will be possible to measure the force exerted to incline the penetration bar 5 by 45 ° (as shown in FIG. 5), in which case it will be possible to provide angular indication means such as an angle scale. on one of the bearings or a tilt sensor integrated in the torque wrench 6, or measure the force exerted to push the penetration bar 5 out of the sporting lawn 7 (as shown in Figure 6).

It can also be seen that the device according to the present invention has as other advantages to involve only relatively simple mechanical parts, thus making it easy and quick to manufacture, that the measurement is provided by a conventional torque wrench which can easily be replaced by case of failure, and that the height of the penetration bar pivot point is fixed, as defined by the axis of rotation of the shaft, which allows to obtain a good repeatability of the measurements.

It is understood that the above embodiment of the present invention has been given as an indication and not limitation and that modifications may be made without departing from the scope of the present invention.

Claims (10)

1 - Device (1) for measuring the resistance to tearing of a sporting lawn (7), characterized in that it comprises: - a platform (2) having a lower surface (2b) for contacting the surface of the sporting lawn (7), and an upper surface (2a) opposite the lower surface (2b) and dimensioned to form a ballast laying surface; - a penetration bar (5) intended to be partially embedded in the sporting lawn (7); - mounting means (3, 4) which are connected to the platform (2) and configured to connect the penetration bar (5) to the platform (2) in a vertically displaceable and pivotable manner around a horizontal axis, so that the penetration bar (5) can be partially driven into the sporting lawn (7) and then pivoted; - means (6) for actuating the penetration bar (5) which are configured to allow the application to the penetration bar (5) of a torque to rotate it after it has partially sunk in the sporty lawn (7); and - means (6) for measuring the torque applied to the penetration bar (5) to rotate it after it has been driven into the sporting lawn (7). 2 - Device (1) according to claim 1, characterized in that it also comprises a ballast, formed by one or more bodies sized to be able to be placed on the upper surface (2a) of the platform (2 ), the upper surface (2a) of the platform (2) being preferably flat. 3 - Device (1) according to one of claims 1 and 2, characterized in that the platform (2) is formed by a parallelepiped plate in which is formed an elongate slot (20), the mounting means ( 3, 4) being configured to connect the penetration bar (5) to the platform (2) in a position such that the penetration bar (5) is able to be partially inserted into the sporting lawn (7) by passing through the lumen (20), the lumen (20) allowing subsequent pivoting of the penetration bar (5). 4 - Device (1) according to claim 3, characterized in that the longitudinal axis of the lumen (20) coincides with one of the two mediators of the platform (2), the upper surface (2a) of the platform (2) having two surface regions, on either side of the light (20), on which a weight can be placed. 5 - Device (1) according to one of claims 1 to 4, characterized in that the mounting means (3, 4) comprise two bearings (3) between which is rotatably mounted a shaft (4) of which longitudinal axis is horizontal, where appropriate with a bearing (3) on each side of the slot (20) and the longitudinal axis of the shaft (4) orthogonal to the longitudinal axis of the slot (20), shaft (4) further comprising a through hole (44) adapted to be traversed by the penetration bar (5) and the mounting means (3, 4) further comprising means for stopping in translation of the penetration bar (5) relative to the shaft (4). 6 - Device (1) according to claim 5, characterized in that the penetration bar (5) comprises at least one through hole (50) perpendicular to the longitudinal axis of the penetration bar (50), the at least a through hole (50) being able to be traversed by an elongated member (51) projecting out of said through hole (50) so as to serve as translation stop while abutting against the shaft (4), the through hole (50) and the elongated member (51) forming said stop means. 7 - Device (1) according to one of claims 1 to 6, characterized in that it comprises means (50, 51) for adjusting the maximum depth at which the penetration bar (5) can be inserted into the sporting lawn (7), the adjusting means (50, 51) being preferably formed by a series of through holes (50) perpendicular to the longitudinal axis of the penetration bar (5) and regularly distributed along of the latter, each through-hole (50) being able to be traversed by an elongated member (51) projecting out of said through-hole (50) so as to serve as translation stop while abutting against the shaft ( 4). 8 - Device (1) according to one of claims 1 to 7, characterized in that the means (6) for actuating the penetration bar (5) and the means (6) for measuring the torque applied at the bar are formed by a torque wrench (6) whose head (61) is connected to means for transforming the pivoting movement of the torque wrench (6) around its head (61) in a pivoting movement of the penetration bar (5). 9 - Device (1) according to claim 8 taken in dependence on claim 5 or one of claims 6 and 7 taken in dependence on claim 5, characterized in that the means for transforming the pivoting movement of the torque wrench (6) around its head (61) in a pivoting movement of the penetration bar (5) comprises the shaft (4) of the mounting means (3, 4), which shaft (4) has a region end projecting from a respective bearing (3) and which has means for coupling to the head (61) of the torque wrench (6), so that a pivoting thereof is translated into a rotational movement of the shaft (4) and thus in a pivoting movement of the penetration bar (5). 10 - Device (1) according to one of claims 1 to 9, characterized in that the penetration bar (5) is provided, in the upper part, with a handle (52), preferably a handle (52) formed by two rigid straight portions (52a) which extend perpendicular to the penetration bar (5), on each side thereof, and are aligned with each other, to improve grip of the penetration bar (5) during its insertion into the sporting lawn (7).