Method for the management of roadcutting and road scarifier implementing said method

The invention concerns a method for the integrated management of the parameters regarding the cutting depth of road surfaces and a road scarifier suitable for implementing said method.

It is known that road scarifiers are machines equipped with a cutting drum that sinks into the road surface for a given depth, in such a way as to remove the asphalt and prepare a bed suitable for the laying of a new asphalt blanket.

Depending on the different needs, the road scarifier must remove the road surface until reaching a given depth, for example 10-15 cm with respect to the road level. Sometimes, besides removing the asphalt in horizontal direction, or in any case parallel to the road surface, it is necessary to remove the asphalt in a different manner from the right to the left side of the road, for example when a road with sloping sides for the drainage of rain must be obtained, that is, a road whose sides are lower with respect to its centre to avoid the stagnation of water.

In this case it may happen that, if the road surface in question does not have this geometrical configuration, to obtain an inclined profile the scarifier must cut the road deeper on one side than on the other. Practically, the cutting drum must not be parallel to the road surface, but inclined of an angle α with respect to the same.

In order to obtain these specific effects in the preparation of the road bed for the laying of a new asphalt blanket, the known road scarifiers use copying devices, like for example tracer points that cooperate with a wire tensioned through a series of pegs arranged on the road side.

According to this method, the tracer point is constantly in contact with the tight wire and when this contact is lost an automatic correction of the machine position takes place by means of hydraulic jacks that operate on the frame, in such a way as to vary the working depth of the cutting drum and restore the contact between tracer point and wire.

If it is not possible to use pegs and tight wire, the machine is equipped with a long linear bar positioned at the side of the machine itself and resting on the road surface, in such a way as to define a median plane that is followed by the machine in operation.

Besides these devices, which substantially control the cutting depth, there are also devices that show the inclination of the cutting drum with respect to the road surface, in such a way as to remove different quantities of asphalt on the left and on the right side of the drum, respectively, and to obtain a given road profile, for example with sloping sides.

More generally, road scarifiers are provided either with sensors positioned on the left and on the right side of the machine and suitable for measuring the distance between the sensor and the cutter contact surface, and with devices controlling the inclination of the cutting drum.

At present these data are read and managed by the machine operator in a non-coordinated way, which means that if the machine must drive the cutter into the road surface for a given depth - for example the same depth on the right and left side - the operator of the machine must programme the right depth control instrument and the left depth control instrument separately, presetting a certain working depth for the right and left sides of the road.

According to the known technique, therefore, the right and left scarification depth control devices cannot exchange information in order to correct any deviation from the preset parameters.

Practically, according to the technique used at present there is no interdependence between the measured parameters regarding right depth, left depth and inclination, which would ensure the complete control of the cutting profile to be obtained.

The aim of the present invention is to overcome the limitations of the known technique.

The main aim of the invention, in fact, is the implementation a road scarifier for the cutting of road surfaces that constantly ensures that the work of the cutting drum on the road surface is performed in such a way as to obtain the desired profile, and therefore following preset parameters.

Said profile should also be automatically respected by the machine, which means that during the operation of the machine automatic correction in response to deviations from the preset parameters should be possible.

Another object of the invention is to facilitate the work for the operator of the machine, by grouping on a single panel the controls regarding the parameters of the scarification profile to be obtained, that is, the right depth, left depth and inclination parameters of the road surface removed.

A further aim to be achieved is that the scarifier control system should make it possible to operate the machine by setting only two of the three parameters of the scarification profile to be obtained, while the third parameter should be derived from the other two.

Another aim of the invention is the implementation of a machine equipped with a device that, whenever a deviation from the preset parameters takes place, intervenes with an automatic correction procedure acting directly on the components that vary the position of the machine and of the cutting drum with respect to the road surface on which the work is being performed.

All the aims mentioned above and others that will be described in greater detail below have been achieved through the implementation of a road scarifier for cutting road surfaces, comprising: <ul id="ul0001" list-style="dash" compact="compact"><li>a frame provided with at least one cutting drum, preferably supported by tracks by means of hydraulic actuators suitable for modifying the relative position of said frame and said tracks, in such a way as to modify the axis of said cutter with respect to the road surface;</li><li>driving means to obtain the setting in motion of the machine and the rotation of said cutter;</li><li>right and left sensors arranged at the sides of the machine and suitable for showing the relative distance between said sensors and the road surface;</li><li>sensors to show the inclination of said machine with respect to the horizontal plane,</li></ul> said road scarifier being characterized in that each of said right and left sensors and said inclination sensor sends signals to first programming and controlling data processing systems, said first data processing systems being suitable for comparing the signals received with preset signals and for emitting difference signals that are received by a second data processing system capable of sending control signals to hydraulic actuators connected to the frame of the machine, in such a way as to reduce to zero the difference signals sent out by said first data processing systems.

The object of the invention includes also the road scarifier operation method for the removal of asphalt from road surfaces through the cutting of the asphalt with preset depth and inclination, comprising a presetting cycle for the definition of the parameters to be obtained and a working cycle according to the contents of the independent claim regarding said method.

Further characteristics and details of the invention will be better highlighted in the description of one favourite application among many of the invention in question, illustrated in the enclosed drawings, wherein: <ul id="ul0002" list-style="dash" compact="compact"><li>Fig. 1 is a front view of the machine object of the invention;</li><li>Fig. 2 is a plan view of the machine object of the invention, showing in particular the position of the hydraulic jacks with which the machine is equipped;</li><li>Fig. 3 is a schematic section of the machine object of the invention along line III-III, showing in particular the hydraulic diagram of the front hydraulic jacks;</li><li>Fig. 4 is a schematic section of the machine object of the invention along line IV-IV, showing in particular the hydraulic diagram of the rear hydraulic jacks and the machine inclination sensor;</li><li>Fig. 5 is a block diagram of the control devices with which the machine object of the invention is equipped;</li><li>Fig. 6 shows a section of the road surface removed by the machine object of the invention;</li><li>Fig. 7 shows by means of a table the possible operation modes of the rear actuators and of the inclination sensor of the machine object of the invention.</li></ul>

With reference to the figures mentioned above, it can be observed that the road scarifier, indicated as a whole by <b>1</b> in Fig. 1, is provided with a frame <b>2</b> supported by tracks <b>3, 4, 5</b> and <b>6</b>, on which the same number of jacks indicated by <b>7, 8, 9</b> and <b>10</b> rest, as shown in Fig. 2.

The road scarifier is equipped with a cutting drum <b>11</b> suitable for working on the road surface <b>12</b> according to the position of the hydraulic jacks that lift or lower the frame <b>2</b> as required by the work programme.

It must be observed that road scarifiers are generally provided with front jacks <b>8</b> and <b>9</b> operated by a single hydraulic control, so that they act together as if they were a single central jack positioned at the front of the machine, as shown in the hydraulic diagram of Fig. 3. On the other hand, as far as the rear jacks <b>7</b> and <b>10</b> are concerned, these are controlled independently of each other and can have different configurations, so that the cutting drum <b>11</b> can be parallel to the road surface, or inclined as much as necessary to obtain the scarification according to a given profile, for example with sloping sides, in such a way as to obtain an asphalt covering having certain specific characteristics.

According to the invention, the road scarifier <b>1</b> is provided on both sides with sensors, indicated by <b>13</b> and <b>14</b>, respectively, that can be seen in Fig. 2 and 1. These sensors can be ultrasound sensors or reflection sensors and serve to measure the distance between said sensors and the road bed.

As it can be observed in the block diagram of Fig. 5, the sensors <b>13</b> and <b>14</b> send their signals to first programming and controlling data processing systems indicated by <b>16</b> and <b>17</b>, respectively. More particularly, the sensors <b>13</b> send their signals to the data processing system <b>16</b> and the mean of said signals is made and shown on a display <b>161</b>.

Analogously, the sensors <b>14</b> send their measure signals to the data processing system <b>17</b>, which shows the mean of the readings on the display <b>171</b>.

As already explained, the road scarifier is also provided with a frame inclination sensor indicated by <b>18</b>, which in fact shows the inclination angle α of the frame with respect to the horizontal line of the machine. Since the cutting drum <b>11</b> is integral with the frame <b>2</b>, the inclination of the frame obviously corresponds to the inclination of the cutting drum, which is the inclination that is actually relevant to the work performed by the machine. Even in this case the inclination sensor <b>18</b> is connected to a further first data processing system <b>19</b> that shows the measured inclination, expressed in degrees, on the display <b>191</b>.

According to the invention, it is possible to set two of the three parameters necessary for the setting of the scarification in the first data processing systems <b>16, 17</b> or <b>19</b>, since the third parameter can be derived from the other two. More particularly, it is possible to set the left and right scarification depth parameters in the data processing systems <b>16</b> and <b>17</b> through the displays <b>162</b> and <b>172</b>, respectively.

Obviously, if the right and left scarification depth values are the same, the angle α on the display <b>192</b> of the data processing system <b>19</b> will be equal to 0. The situation will be different if the left scarification depth value differs from the right scarification depth value and in this case the value of the angle α will be derived directly from the difference between the two values set.

It is clear, therefore, that to preset the operation parameters of the road scarifier it will be necessary to preset two of the first three data processing systems <b>16, 17</b> and <b>19</b>, that is, the respective values required, the third value resulting directly from the other two.

More particularly, if the two scarification depth values are set, the inclination angle value will be set as a consequence of the other two.

It is also possible to set the value of the left or right scarification depth together with the desired inclination angle, and the other right or left scarification depth value will be consequently defined and preset and then automatically displayed by the first data processing systems.

When the machine is in operation, each data processing system <b>16, 17</b> or <b>19</b> carries out a comparison between the scarification depth or angle set and the corresponding readings, by means of an electronic processor. Consequently, a difference signal δS, δD and δα is sent out by the first data processing system <b>16</b>, or <b>17</b>, or <b>19</b>, respectively. These difference signals are received by a second data processing system PLC, indicated as a whole by <b>20,</b> which processes the signals received and sends control signals to hydraulic left and right actuators, indicated by <b>21</b> and <b>22,</b> respectively, which control the hydraulic cylinder <b>10</b> and the hydraulic cylinder <b>7,</b> respectively, so that the lifting or lowering of each one of the hydraulic cylinders tends to reduce to zero the difference signals δ received by the first data processing systems <b>16, 17</b> and <b>19</b>.

It is clear that in this way the road scarifier object of the invention, with its control device, controls all the parameters regarding the scarification carried out by the cutting drum and adapts the position of the machine through the operation of the hydraulic jacks, in such a way as to follow the desired scarification profile.

From an operational point of view, the first step necessary to carry out the scarification according to preset parameters as described herein is represented by the setting of the parameters, which is followed by the actual scarification process.

For the parameter setting cycle, first of all it is necessary to operate the hydraulic jacks of the machine, in such a way as to lift the frame with the maximum extension, that is, at the maximum distance of the same from the ground, after which the jacks must be lowered until the cylinder rests on the ground. With the cylinder resting on the ground and parallel to the road surface to be scarified, the measured values shown by the displays <b>162, 172</b> and <b>192</b> are read and then set to zero by means of the reset buttons positioned on each first data processing system, indicated by <b>163, 173</b> and <b>193</b>. Once the values are set to zero, the desired values are set in two of the three displays <b>162, 172, 192</b> belonging to the data processing systems <b>16, 17</b> and <b>19</b>, according to one of the combinations shown by the table in Fig. 7. For example, as it can be observed for the setting <b>1</b> of the selector <b>30</b>, the value LS can be set in the display <b>162</b>, the value LD in the display <b>172</b>, and the angle α will be set in the display <b>192</b> as a consequence of the other two settings.

Another option is available, according to position <b>2</b> of the selector <b>30</b> of Fig. 7, if the operator decides to set the right scarification depth value LB and the inclination angle α. In this case the left scarification value LS will automatically derive from the other two settings.

It may also happen, as shown in line <b>4</b> and <b>5</b> of the table of Fig. 7, that the left or right cylinder respectively are kept inoperative and therefore fixed in their initial position. The position <b>6</b> indicates that the machine is at rest.

Therefore, once two of the three reference values have been set, as explained above, in each one of the first data processing systems <b>16, 17,</b> or <b>19</b>, it is possible to start the work.

As soon as the scarification work is started, the sensors <b>13, 14</b> and <b>18</b> transmit the scarification depth and inclination angle values measured to the respective data processing systems. These values are compared with the set depth and inclination angle values and, if there is a difference between the values read and those set, the first data processing systems send out a difference signal δS, δD or δα. These signals are received by a data processing unit, for example a PLC indicated by <b>20</b>, which sends out one or two signals, <b>21</b> and <b>22</b>, that operate the hydraulic actuators <b>7</b> and <b>10.</b> Said cylinders are operated in order to obtain a variation in the position of the frame <b>2</b>, in such a way as to reduce to zero the difference δ5, δD or δα signalled by the first data processing systems <b>16, 17</b> and <b>19</b>.

If the machine keeps working with constant value readings and if the readings substantially correspond to the preset values, no difference signal will be sent out by the first data processing systems and consequently the PLC <b>20</b> will not emit any signal to operate the hydraulic actuators <b>7</b> and <b>10</b>.

It is clear that, according to the invention, it is possible to obtain the full automatic control of the geometrical configuration of the scarification profile, after presetting the starting data.

It is also obvious that thanks to this possibility of presetting the parameters the road scarifier can obtain any scarification profile, an example of which is shown in Fig. 6.