Abstract:
A control method including providing a control device arranged to adjust a supply parameter of a percussion apparatus, providing a control unit arranged to apply a control instruction to the control device, switching on the percussion apparatus, measuring at least one sound data in the vicinity of a predetermined area, transmitting the at least one measured sound data to the control unit, comparing the at least one sound data received by the control unit with a predetermined threshold value, correcting the control instruction of the control device depending on the at least one received sound data, and applying, by means of the control unit, the corrected control instruction to the control device.

Description:
TECHNICAL FIELD 
       [0001]    The present invention concerns a method for controlling a supply parameter of a percussion apparatus actuated by a pressurized incompressible fluid, and an assembly for implementing this method. 
       BACKGROUND 
       [0002]    A percussion apparatus, called hydraulic rock breaker, is commonly used for various applications, such as quarry blocks breaking, demolition works or trenching. A hydraulic rock breaker includes particularly a striking piston arranged to cyclically strike a tool so as to produce impact energy on the material to be demolished. When using a rock breaker, the latter generates a significant running noise that propagates within the immediate environment of the rock breaker in the form of sound waves likely to induce noise nuisances for people located in the vicinity of the rock breaker. 
         [0003]    In order to limit the impact of these noise nuisances, the use of a rock breaker can be limited, even forbidden, below a minimum distance around sensitive areas, that is to say around areas inhabited or occupied by third parties, such as residential areas, areas of industrial, commercial or agricultural activities, or even education, care or rest areas. 
         [0004]    Furthermore, the choice of a rock breaker model can be conditioned by the type of work to be performed. For example, when work must be carried out in the vicinity of sensitive areas, it may be necessary to select a low-powered rock breaker to limit the noise nuisances. 
         [0005]    These noise nuisances can be significantly variable, particularly in urbanized environment, due to the field variability, thus to the materials absorption coefficients, and due to the site configuration with possible reflections of the sound waves on buildings or neighboring structures. As a result, it is very difficult to predict the sound levels perceived within a predetermined area located in the vicinity of the rock breaker. 
         [0006]    Under these conditions, the variability of these noise nuisances makes the use of rock breaker particularly delicate. To overcome this problem, it is common for a project manager to impose the use of a very low-powered rock breaker, the speed of execution of work is then slow and the costs of work become significant. 
         [0007]    To overcome this drawback, it is known to record, for the whole duration of the work carried out in the vicinity of sensitive areas, the sound levels of sound waves propagating in the vicinity of these sensitive areas, thanks to the use of a detection system particularly comprising one or more microphone(s) and a recorder arranged to check the sound levels measured by the microphone(s). 
         [0008]    Thus, the rock breaker operator can be informed of the noise nuisance he caused on the environment, and he may if necessary replace the rock breaker used by a lower-powered model of rock breakers. 
         [0009]    In all cases, the use of a rock breaker in the vicinity of sensitive areas remains subject to human error, and it is common that the maximum permissible sound levels are exceeded. 
       BRIEF SUMMARY 
       [0010]    The present invention aims to remedy these drawbacks by providing a control method and an assembly for its implementation, allowing to limit the noise nuisances generated during the work accomplishment using a percussion apparatus, below a maximum permissible value. 
         [0011]    To this end, the present invention concerns a control method for controlling a supply parameter of a percussion apparatus actuated by a pressurized incompressible fluid, characterized in that it comprises the following steps:
       providing a control device arranged to adjust a supply parameter of the percussion apparatus,   providing a control unit arranged to apply a control instruction to the control device,   switching on the percussion apparatus,   measuring at least one sound data in the vicinity of a predetermined area,   transmitting the at least one measured sound data to the control unit,   comparing the at least one sound data received by the control unit with a predetermined threshold value,   correcting the control instruction of the control device depending on the at least one received sound data, and   applying, by means of the control unit, said corrected control instruction to the control device so as to adjust the supply parameter of the percussion apparatus depending on the measured sound data.       
 
         [0020]    Thus, the control method according to the invention allows adjusting automatically, via the control unit and the control device, a supply parameter, such as the supply flow rate or the supply pressure, of the percussion apparatus depending on the measured sound data in the vicinity of the predetermined area. These dispositions allow optimizing the operation of the percussion apparatus, while avoiding that the sound levels of the sound waves generated by the percussion apparatus and propagating in the vicinity of sensitive areas do not exceed the predetermined threshold value. 
         [0021]    According to one mode of implementation of the control method, the predetermined area is an area inhabited or occupied by third parties, such as a residential area, an area of industrial, commercial or agricultural activities, or even an education, care or rest area. 
         [0022]    According to one mode of implementation of the invention, the predetermined area is moved relative to the percussion apparatus. 
         [0023]    According to one mode of implementation of the control method, the control instruction is corrected such that the supply parameter adjusted by the control device induces sound data, advantageously in the vicinity of the predetermined area, lower than the predetermined threshold value. 
         [0024]    According to one mode of implementation of the control method, the control instruction is corrected taking into account the predetermined threshold value. 
         [0025]    According to one mode of implementation of the control method, the latter comprises iteratively repeating the measurement, transmission, comparison, correction and application steps. 
         [0026]    According to one mode of implementation of the control method, the latter comprises setting, particularly by an operator input, the predetermined threshold value. These dispositions allow adapting the predetermined threshold value depending on the predetermined area to be protected. 
         [0027]    According to one mode of implementation of the control method, if the at least one received sound data is greater than the predetermined threshold value, the correction step comprises correcting the control instruction of the control device so as to decrease the supply parameter of the percussion apparatus. 
         [0028]    According to one mode of implementation of the control method, if the at least one received sound data is lower than the predetermined threshold value, the correction step comprises correcting the control instruction of the control device so as to increase the supply parameter of the percussion apparatus. 
         [0029]    According to one mode of implementation of the control method, if the at least one received sound data is lower than the predetermined threshold value and if the difference between the at least one received sound data and the predetermined threshold value is greater than a predetermined limit value, the correction step comprises correcting the control instruction of the control device so as to increase the supply parameter of the percussion apparatus. 
         [0030]    According to one mode of implementation of the control method, if the at least one received sound data is lower than the predetermined threshold value and if the difference between the at least one received sound data and the predetermined threshold value is lower than the predetermined limit value, the correction step comprises maintaining the value of the previously applied control instruction. 
         [0031]    According to one mode of implementation, the control method comprises a interrupting the supply of the pressurized incompressible fluid to the percussion apparatus when the at least one sound data received by the control unit is greater than the predetermined threshold value and when simultaneously the supply parameter of the percussion apparatus is adjusted to its minimum by the control device. These dispositions allow automatically interrupting the supply of the pressurized incompressible fluid to the percussion apparatus so as to protect the predetermined area from the sound waves produced by the percussion apparatus. In such case, the operator must for example take the percussion apparatus away from the predetermined area before restarting said percussion apparatus. 
         [0032]    According to one mode of implementation of the invention, the measurement step comprises measuring the sound level of the sound waves propagating in the vicinity of the predetermined area. 
         [0033]    According to one mode of implementation of the control method, the latter comprises providing means for measuring sound data in the vicinity of the predetermined area. 
         [0034]    According to one mode of implementation of the invention, the measurement step is carried out with one or more microphone(s) disposed in the vicinity of the predetermined area. 
         [0035]    According to one mode of implementation, the control device is arranged to adjust, for example stepwise or continuously, the supply parameter of the percussion apparatus between a minimum value and a maximum value. According to one mode of implementation, the control device is arranged to adjust the supply parameter of the percussion apparatus in different values comprised between the minimum and maximum values. 
         [0036]    According to one mode of implementation, the control method comprises moving a control member comprised in the control device between a first control position corresponding to a maximum value of the supply parameter and a second control position corresponding to a minimum value of the supply parameter. 
         [0037]    According to one mode of implementation of the control method, the control instruction initially applied to the control device, that is to say, upon switching-on the percussion apparatus, is determined so as to adjust the supply parameter to a minimum value. 
         [0038]    According to one mode of implementation of the control method, the step of moving the control member is carried out continuously or stepwise. 
         [0039]    According to one mode of implementation of the control method, the latter comprises determining the predetermined area and of providing means for measuring the sound data in the vicinity of the predetermined area. 
         [0040]    The present invention further concerns an assembly comprising:
       a percussion apparatus actuated by a pressurized incompressible fluid, including a striking piston arranged to strike a tool during each operating cycle of the percussion apparatus,   a control device arranged to adjust a supply parameter of the percussion apparatus,   a control unit arranged to apply a control instruction to the control device,   sound data measuring means intended to be disposed in the vicinity of a predetermined area,   transmission means connected to the sound data measuring means and arranged to transmit the sound data measured by the measuring means,       
 
         [0046]    the control unit being arranged to:
       receive the sound data transmitted by the transmission means,   compare the received sound data with a predetermined threshold value,   correct the control instruction of the control device depending on the received sound data, and   apply said corrected control instruction to the control device so as to adjust the supply parameter of the percussion apparatus depending on the received sound data.       
 
         [0051]    According to one embodiment of the invention, the predetermined area is an area inhabited or occupied by third parties, such as a residential area, an area of industrial, commercial or agricultural activities, or an education, care or rest area. 
         [0052]    According to one embodiment of the invention, the control unit is arranged to correct the control instruction such that the supply parameter adjusted by the control device induces sound data, advantageously in the vicinity of the predetermined area, lower than the predetermined threshold value. 
         [0053]    According to one embodiment of the invention, when the sound data received by the control unit are greater than the predetermined threshold value, the control unit is arranged to correct the control instruction of the control device so as to decrease the supply parameter. 
         [0054]    According to one embodiment of the invention, when the sound data received by the control unit are lower than the predetermined threshold value, the control unit is arranged to correct the control instruction of the control device so as to increase the supply parameter. 
         [0055]    According to one embodiment of the invention, when the sound data received by the control unit are lower than the predetermined threshold value and when simultaneously the difference between the received sound data and the predetermined threshold value is greater than a predetermined limit value, the control unit is arranged to correct the control instruction of the control device so as to increase the supply parameter. 
         [0056]    According to one embodiment of the invention, the assembly comprises a high-pressure supply circuit intended to supply the pressurized incompressible fluid to the percussion apparatus, and a low-pressure return circuit. 
         [0057]    According to one embodiment of the invention, the percussion apparatus comprises a body delimiting a cylinder in which the striking piston is movably mounted in an alternative manner. 
         [0058]    For example, the striking piston and the cylinder delimit at least one lower chamber permanently connected to the high-pressure supply circuit and an upper chamber alternately linked to the high-pressure supply circuit and the low-pressure return circuit. 
         [0059]    According to one feature of the invention, the control unit is arranged to control the supply interruption of the pressurized incompressible fluid to the percussion apparatus when the sound data received by the control unit are greater than the predetermined threshold value and when simultaneously the supply parameter is adjusted to its minimum by the control device. 
         [0060]    According to one embodiment of the invention, the assembly comprises a blocking device arranged to block the high-pressure supply circuit. 
         [0061]    According to one embodiment of the invention, the blocking device is mounted on the high-pressure supply circuit. 
         [0062]    According to one embodiment of the invention, the blocking device comprises a movable blocking member between a blocking position wherein said blocking member blocks the high-pressure supply circuit, and a release position wherein said blocking member releases the high-pressure supply circuit. 
         [0063]    According to one embodiment of the invention, the control unit is arranged to control the movement of the blocking member between its blocking and release positions. 
         [0064]    According to one embodiment of the invention, the blocking device comprises an actuating element arranged to move the blocking member between its blocking and release positions. 
         [0065]    According to one embodiment of the invention, the actuating element is arranged to receive a control instruction from the control unit, and to move the blocking member depending on the control instruction. 
         [0066]    According to one embodiment of the invention, the blocking device is a solenoid valve, and for example an on-off solenoid valve, such as a normally open solenoid valve or a normally closed solenoid valve. 
         [0067]    According to one embodiment of the invention, the measurement means are arranged to measure the sound levels of the sound waves propagating in the vicinity of the predetermined area. 
         [0068]    According to one feature of the invention, the measurement means include one or more microphone(s) intended to be disposed in the vicinity of the predetermined area. 
         [0069]    According to one feature of the invention, the control device comprises a control member movable between a first control position corresponding to a maximum value of the supply parameter and a second control position corresponding to a minimum value of the supply parameter. 
         [0070]    According to one embodiment of the invention, the control device is external to the percussion apparatus. 
         [0071]    According to one embodiment of the invention, the control device is hydraulic. 
         [0072]    According to one embodiment of the invention, the control unit is arranged to control the movement of the control member between its first and second positions, and for example continuously or stepwise. 
         [0073]    According to one embodiment of the invention, the control device is provided so with an actuating member arranged to move the control member between its first and second control positions. 
         [0074]    According to one embodiment of the invention, the actuating member is arranged to receive the corrected control instruction from the control unit, and to move the control member depending on the corrected control instruction. 
         [0075]    According to one embodiment of the invention, the control device comprises a pressure regulator, and for example a proportional control-type pressure regulator. 
         [0076]    According to one embodiment of the invention, the control device is mounted on the high-pressure supply circuit. 
         [0077]    According to one feature of the invention, the control device is arranged to adjust the supply pressure, also called operating pressure, of the percussion apparatus between a minimum supply pressure and a maximum supply pressure. 
         [0078]    According to one embodiment of the invention, the control device is arranged to adjust continuously or stepwise the supply pressure of the percussion apparatus between the minimum and maximum supply pressures. 
         [0079]    According to one embodiment of the invention, the control unit is arranged to correct the control instruction of the control device so as to decrease the supply pressure of the percussion apparatus when the sound data received by the control unit are greater than the predetermined threshold value. 
         [0080]    According to one embodiment of the invention, the control unit is arranged to correct the control instruction of the control device so as to increase the supply pressure of the percussion apparatus when the sound data received by the control unit are lower than the predetermined threshold value. 
         [0081]    According to one embodiment of the invention, the control device comprises a flow rate regulator, and for example a proportional control-type flow rate regulator. 
         [0082]    According to one embodiment of the invention, the control device is arranged to adjust the supply flow rate of the percussion apparatus between a minimum supply flow rate and a maximum supply flow rate. 
         [0083]    According to one embodiment of the invention, the control device is arranged to adjust continuously or stepwise the supply flow rate of the percussion apparatus between the minimum and maximum supply flow rates. 
         [0084]    According to one embodiment of the invention, the control unit is arranged to correct the control instruction of the control device so as to decrease the supply flow rate of the percussion apparatus when the sound data received by the control unit so are greater than the predetermined threshold value. 
         [0085]    According to one embodiment of the invention, the control unit is arranged to correct the control instruction of the control device so as to increase the supply flow rate of the percussion apparatus when the sound data received by the control unit are lower than the predetermined threshold value. 
         [0086]    According to one embodiment of the invention, the assembly comprises a variable displacement supply pump connected to the high-pressure supply circuit, and the control device is arranged to adjust the displacement of the supply pump between a minimum displacement and a maximum displacement. 
         [0087]    According to one embodiment of the invention, the control unit and the percussion apparatus are intended to be mounted on a carrier machine, such as a hydraulic shovel. 
         [0088]    According to one embodiment of the invention, the assembly comprises setting means arranged to set, particularly by an operator input, the predetermined threshold value. 
         [0089]    According to one embodiment of the invention, the control unit includes a receiver arranged to receive the sound data transmitted by the transmission means. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0090]    Anyway, the invention will be better understood using the following description with reference to the appended schematic drawing showing, by way of non-limiting examples, three embodiments of this assembly. 
           [0091]      FIG. 1  is a schematic view of an assembly according to a first embodiment of the invention. 
           [0092]      FIG. 2  is a schematic view of an assembly according to a second embodiment of the invention. 
           [0093]      FIG. 3  is a schematic view of an assembly according to a third embodiment of the invention. 
           [0094]      FIG. 4  is a schematic view of an assembly according to a fourth embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0095]      FIG. 1  shows an assembly according to a first embodiment of the invention comprising a percussion apparatus  2 , such as a hydraulic rock breaker, mounted on a carrier machine  3 , such as a hydraulic shovel. 
         [0096]    The percussion apparatus  2  comprises a stepped striking piston  4  slidably mounted in an alternative manner within a cylinder  5  arranged in a body  6  of the percussion apparatus  2 . During each operating cycle of the percussion apparatus  2 , the striking piston  4  strikes the upper end of a tool  7  slidably mounted in a bore  8  arranged in the body  3  coaxially to the cylinder  5 . The striking piston  4  and the cylinder  5  delimit for example a lower chamber (not shown in the figures) fluidly connected permanently to a high-pressure supply circuit  9  intended to supply the pressurized incompressible fluid to the percussion apparatus  2  and an upper chamber (not shown in the figures) with a more significant section arranged above the striking piston  4 . 
         [0097]    The percussion apparatus  2  further comprises a distributor (not shown in the figures) mounted in the body  6  and arranged to alternately link the upper chamber to the high-pressure supply circuit  9 , during the striking stroke of the striking piston  4 , and with a low-pressure return circuit  11  during the rising stroke of the striking piston  4 . 
         [0098]    The assembly further comprises at least one microphone  12  intended to be disposed in the vicinity of an area to be protected  13  such as a building inhabited or occupied by third parties, so as to measure sound data, such as the sound level, related to sound waves  14  propagating in the vicinity of the area  13  and generated by the operation of the percussion apparatus  2 . According to one embodiment of the invention, the assembly may comprise several microphones  12 . 
         [0099]    The assembly also comprises a transmitter  15  connected to the microphone  12 , and arranged to transmit the sound data measured by the microphone  12 . The transmitter  15  is preferably disposed in the vicinity of the microphone  12 , and thus of the area to be protected  13 . 
         [0100]    The assembly further comprises a control device  16  external to the percussion apparatus  2  and arranged to adjust the supply flow rate of the percussion apparatus  2 , and a control unit  17  arranged to apply a control instruction to the control device  16 . 
         [0101]    According to the embodiment shown in  FIG. 1 , the control device  16  is hydraulic and formed by a proportional control flow rate regulator  18  mounted on the high-pressure supply circuit  9  downstream of a supply pump  19  disposed on the carrier machine  3 . 
         [0102]    The flow rate regulator  18  comprises a control member  20  movable between a first control position corresponding to a maximum supply flow rate of the percussion apparatus  2  and a second control position corresponding to a minimum supply flow rate of the percussion apparatus  2 . The flow rate regulator  18  further comprises an actuating coil  21  arranged to receive the control instruction from the control unit  17 , and to move the control member  20  between its first and second control positions depending on the received control instruction. 
         [0103]    The assembly further comprises a return line  22  fluidly connected on the one hand to a low-pressure tank  23  and on the other hand to the flow rate regulator  18 . The return line  22  and the upstream and downstream portions of the high-pressure supply circuit  9  advantageously open into a cylinder (not shown in the figures) in which the control member  20  is slidably mounted. 
         [0104]    The flow rate regulator  18  is particularly arranged to deviate towards the return line  22 , a more or less significant part of the fluid flow rate provided by the supply pump  19  depending on the position of the control member  20 , and thus of the control instruction applied to the actuating coil  21  by the control unit  17 . 
         [0105]    The control unit  17  is arranged to:
       receive the sound data transmitted by the transmitter  15 .   compare the received sound data with a predetermined threshold value,   correct the control instruction of the control device  16  depending on the received sound data, and   apply the corrected control instruction to the control device  16  so as to adjust the supply flow rate of the percussion apparatus  2 .       
 
         [0110]    The control unit  17  is more particularly arranged to:
       correct the control instruction of the control device  16  so as to decrease the supply flow rate of the percussion apparatus  2  when the sound data received by the control unit  17  are greater than the predetermined threshold value, and   correct the control instruction of the control device  16  so as to increase the supply flow rate of the percussion apparatus  2  when the sound data received by the control unit  17  are lower than the predetermined threshold value.       
 
         [0113]    Thus, when the percussion apparatus  2  is operating, the sound levels values, or the maximum of these sound levels values, sound waves  14  generated by the percussion apparatus  2  and propagating in the vicinity of the area  13  are measured by the microphones  12  and transmitted by the transmitter  15  to the control unit  17 . These values are then compared to the predetermined threshold value. When these values exceed the predetermined threshold value, then the control unit  17  applies a control instruction to the control device  16  so as to decrease the supply flow rate of the percussion apparatus  2 , and thus the percussion apparatus power, and this in order to limit the noise nuisances generated by the percussion apparatus. On the contrary, when these values are lower than the predetermined threshold value, then the control unit  17  applies a control instruction to the control device  16  so as to increase the supply flow rate of the percussion apparatus  2  so as to increase the percussion apparatus power, and this in order to optimize the operation of the percussion apparatus  2  without exceeding the maximum permissible sound values within the sensitive area to be protected. 
         [0114]    According to the embodiment shown in  FIG. 1 , the assembly also comprises a pressure switch  24  arranged to measure the pressure in the high-pressure supply circuit  9 . The pressure switch  24  is advantageously connected to the control unit  17  so as to transmit to the latter the measured pressure values. 
         [0115]      FIG. 2  shows an assembly according to a second embodiment of the invention which differs from the assembly shown in  FIG. 1  mainly in that the supply pump  19  is a variable displacement pump, and in that the control device  16  is formed by a control device  25  arranged to adjust the displacement of the supply pump  19  between a minimum displacement and a maximum displacement. The control device  25  is thus arranged to adjust, via the supply pump  19 , the supply flow rate of the percussion apparatus  2  between a minimum supply flow rate and a maximum supply flow rate. 
         [0116]    The control device  25  comprises a control member  26 , such as an actuator, arranged to cooperate with the supply pump  19  and movable between a first control position corresponding to a maximum supply flow rate of the percussion apparatus  2  and a second control position corresponding to a minimum supply flow rate of the percussion apparatus  2 . 
         [0117]    The control device  25  further comprises a control unit  27  arranged to receive the control instruction from the control unit  17 , and to move the control member  26  between its first and second control positions depending on the received control instruction. 
         [0118]    According to this embodiment of the invention, the control unit  17  is arranged to:
       correct the control instruction of the control device  16  so as to decrease the displacement of the supply pump  19 , and thus the supply flow rate of the percussion apparatus  2 , when the sound data received by the control unit  17  are greater than the predetermined threshold value, and   correct the control instruction of the control device  16  so as to increase the displacement of the supply pump  19 , and thus the supply flow rate of the percussion apparatus  2 , when the sound data received by the control unit  17  are lower than the predetermined threshold value.       
 
         [0121]      FIG. 3  shows an assembly according to a third embodiment of the invention which differs from the assembly shown in  FIG. 1  mainly in that the control device  16  is formed by a proportional control pressure regulator  28  mounted on the high-pressure supply circuit  9 , and arranged to adjust the supply pressure of the percussion apparatus  2  between a minimum supply pressure and a maximum supply pressure. 
         [0122]    The pressure regulator  28  comprises a control member  29  movable between a first control position corresponding to the maximum supply pressure of the percussion apparatus  2  and a second control position corresponding to the minimum supply pressure of the percussion apparatus  2 . The pressure regulator  28  further comprises an actuating coil  30  arranged to receive the control instruction from the control unit  17 , and to move the control member  29  between its first and second control positions depending on the received control instruction. 
         [0123]    According to this embodiment of the invention, the control unit  17  is arranged to:
       correct the control instruction of the control device  16  so as to decrease the supply pressure of the percussion apparatus  2  when the sound data received by the control unit  17  are greater than the predetermined threshold value, and   correct the control instruction of the control device  16  so as to increase the supply pressure of the percussion apparatus  2  when the sound data received by the control unit  17  are lower than the predetermined threshold value.       
 
         [0126]      FIG. 4  shows an assembly according to a fourth embodiment of the invention which differs from the assembly shown in  FIG. 3  mainly in that the control unit  17  is arranged to control the interruption of the supply of the pressurized incompressible fluid to the percussion apparatus  2  when the sound data received by the control unit  17  are greater than the predetermined threshold value and when simultaneously the supply pressure of the percussion apparatus  2  is adjusted to its minimum by the control device  16 . 
         [0127]    According to the embodiment shown in  FIG. 4 , the assembly comprises a blocking device  31  mounted on the high-pressure supply circuit  9 , and arranged to block the high-pressure supply circuit  9 . The blocking device  31  is for example disposed between the supply pump  19  and the control device  16 . 
         [0128]    The blocking device  31  is advantageously formed by a solenoid valve  32  and for example an on-off solenoid valve, such as a normally open solenoid valve or a normally closed solenoid valve. 
         [0129]    The solenoid valve  32  advantageously comprises a blocking member  33  movable between a blocking position wherein the blocking member  33  blocks the high-pressure supply circuit  9 , and a release position wherein the blocking member  33  releases the high-pressure supply circuit  9 . The solenoid valve  32  further comprises an actuating coil  34  arranged to receive a control instruction from the control unit  17 , and to move the blocking member  33  between its blocking and release positions depending on the received control instruction. 
         [0130]    Thus, when the supply pressure of the percussion apparatus is adjusted to its minimum by the control device  16 , and when simultaneously the sound data received by the control unit  17  are greater than the predetermined threshold value, the control unit  17  applies a control instruction to the solenoid valve  32 , and particularly to its actuating coil  34  so as to control movement of the blocking member  33  towards its blocking position. These dispositions allow automatically interrupting the supply of the pressurized incompressible fluid to the percussion apparatus  2 , and then protecting the area  13  of the sound waves produced by the percussion apparatus  2 . 
         [0131]    According to variant of the invention, the blocking device  31  could be integrated with the assemblies according to the invention shown in  FIGS. 1 and 2 . In this case, the control unit  17  would be arranged to control interruption of the supply of pressurized incompressible fluid to the percussion apparatus  2  when the sound data received by the control unit  17  are greater than the predetermined threshold value and when simultaneously the supply flow rate of the percussion apparatus  2  is adjusted to its minimum by the control device  16 . 
         [0132]    It goes without saying that the invention is not limited to the sole embodiments of this assembly, described above as example, it encompasses on the contrary all the variants.