Patent Publication Number: US-10322449-B2

Title: De-coring vibrator or pneumatic hammer for de-coring of foundry castings with back connectors

Description:
This application is a National Stage Application of International Application No. PCT/IB2015/054315, filed 8 Jun. 2015, which claims benefit of Serial No. TO2014A000460, filed 9 Jun. 2014 in Italy and which applications are incorporated herein by reference. To the extent appropriate, a claim of priority is made to each of the above disclosed applications. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to a pneumatic vibrator, also known in the industry as pneumatic hammer, for de-coring of castings made from aluminium, steel and iron alloys. 
     For the purposes of the present description, the term de-coring refers, in general, to removal of sand material from foundry castings. 
     Also, for the purposes of the present description, the term castings refers to parts/objects obtained by casting metals into suitable moulds. 
     Patent WO2007006936 describes a pneumatic hammer or de-coring vibrator. 
     The vibrator or hammer comprises a jacket comprising holes for inlet and outlet of compressed air. Inside the jacket there is a mechanical assembly consisting of a cylinder in which a piston slides under the action of compressed air. Said piston comes into contact with a punch, which in turn hits the casting to be subjected to de-coring. 
     Said hammer comprises a connection flange that allows it to be anchored, through fasteners such as socket-head screws, to a de-coring machine. 
     Said jacket of prior-art hammers is made of cast iron to ensure the desired strength characteristics. 
     No hammers are known wherein the jacket is made of a material other than cast iron, particularly in the field of high-performance de-coring hammers. 
     Said jacket is made as one cast monolithic piece. 
     The use of cast iron significantly increases the total weight of the hammer and requires much milling work, and hence much labour, for making the hollow hole that houses the mechanical assembly. 
     The use of cast iron also poses some limits as concerns stress resistance, due to the rigidity of the material and the resulting difficult damping of vibrations, which can propagate to the de-coring machine with which the hammer or vibrator is associated. 
     It is also known that these hammers are to be used in adverse environments where temperatures are very high. In such working conditions, operators must carry out their tasks quickly. It is therefore necessary that de-coring hammers can be easily connected to and removed from the de-coring machine, like the one described in patent EP1995002A2. 
     The solutions according to the prior art turn out to be difficult to handle, because the various compressed air inlet and outlet circuits are arranged in different areas, thus requiring more work to connect and disconnect the various air circuits. 
     Also, the hammers must operate at high temperatures, and there is a risk that the mechanisms that generate piston motion upon intake of compressed air might expand, leading to increased friction between the parts, resulting in decreased efficiency of the hammer, and requiring periodic maintenance. 
     De-coring hammers require high performance in terms of exerted force and piston oscillation frequency, in order to ensure fast and accurate de-coring of metal or alloy castings. 
     The hammer&#39;s performance is mainly checked by constantly monitoring the pulse frequency of the air exiting the cylinder. This type of check is cheap, but suffers from much uncertainty. 
     Other checking methods also exist, which can monitor the oscillation frequency of the beating mass within the cylinder. This is done by means of a sensor located on the jacket surface. Normally said sensor is connected to a processing circuit external to the hammer. 
     Said sensor is not protected, and therefore, when removing a hammer, said sensor may suffer damage caused, for example, by shocks. 
     No hammer currently exist in the art which comprises an integrated sensor that is protected against shocks; as a matter of fact, since the jacket is made as one monolithic piece and has a shape dictated by the standards enforced by the manufacturers of the machines whereto such hammers will have to applied, no protections exist for such sensors. 
     SUMMARY OF THE INVENTION 
     The present invention aims at solving one or more of the above-mentioned problems by providing an improved de-coring vibrator or hammer wherein at least the compressed air outlet connector, just like the inlet connector, is located at the second end of the hammer, preferably in proximity to the inlet connector. 
     One aspect of the present invention relates to a hammer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features and advantages of the hammer will become apparent from the following description of at least one exemplary and non-limiting embodiment thereof and from the annexed drawings, wherein: 
         FIGS. 1A and 1B  show different views of the hammer or vibrator according to the present invention; in particular,  FIG. 1A  shows the hammer with an associated measurement circuit, and  FIG. 1B  shows a side view of a de-coring vibrator or hammer according to the present invention; 
         FIGS. 2A and 2B  show the hammer or vibrator of  FIG. 1 ; in particular,  FIG. 2A  is an exploded view and 
         FIG. 2B  is a sectional side view along the vertical plane; 
         FIG. 3  shows a side view of a jacket of the hammer or vibrator of  FIGS. 2A-2B ; 
         FIGS. 4A-4D  show some rear views of the jacket of  FIG. 3 ; in particular,  FIG. 4A  is a sectional view along the plane  4 A- 4 A, which shows the connection between the outlet opening and the exit duct;  FIG. 4B  is a sectional view along the plane  4 B- 4 B, which shows the exit duct, the housing for the measurement circuit, and the measurement duct;  FIG. 4C  is a sectional view along the plane  4 C- 4 C, which shows the junction between the exit duct and the exit chamber and the channel for the communication line;  FIG. 4D  is a view of the rear part of the jacket, wherein the holes for the various circuits are visible. 
     
    
    
     DETAILED DESCRIPTION 
     With reference to the above-listed drawings, pneumatic hammer or de-coring vibrator  2  is suitable for de-coring of foundry castings. 
     Hammer  2  comprises a jacket  3 , in turn comprising an inner chamber  32 ; an inlet circuit  4  for the entry of compressed air, and an outlet circuit  5  for the exit of compressed air. 
     Said hammer  2  also comprises, by way of non-limiting example, a connection flange  36  through which hammer  2  can be connected to a de-coring machine. Preferably, said connection flange  36  is comprised in jacket  3  as one piece. 
     One example of embodiment of the jacket is shown by way of example in  FIGS. 3, 4A-4D . 
     Hammer  2  further comprises a motion mechanism  7 , for generating a reciprocating vibratory motion under the action of compressed air. 
     In an exemplary but non-limiting embodiment, said motion mechanism is such that it allows a linear motion along an axis “Z”, which is preferably the longitudinal axis of hammer  2  itself, between a retracted position and a working position, under the action of compressed air. 
     Motion mechanism  7  is arranged within inner chamber  32  of jacket  3 , as can be seen, for example, in the exemplary embodiment of  FIGS. 2A-2B . 
     Hammer or vibrator  2  further comprises a punch or beater  6 , connected to said motion mechanism  7 , for coming into contact with the casting to be subjected to de-coring. Said punch or beater  6  constitutes a first end of hammer  2 . 
     Said inlet circuit  4  comprises an inlet connector  41  allowing the connection of the hammer to a compressed air circuit. Said inlet connector is located at a second end of hammer  2 , opposite to punch  6 . 
     Said outlet circuit  5  comprises an outlet connector  54  for connecting hammer  2  to an air recovery circuit. 
     Said outlet connector  54  is located at the second end of hammer  2 , in proximity to the inlet connector. 
     Said motion mechanism  7  is adapted to impart a vibratory motion to punch or beater  6 , for the purpose of achieving an optimal de-coring effect. 
     Said motion mechanism  7  is also adapted to move said punch  6  at least linearly along said axis “Z”. 
     Hammer or vibrator  2  further comprises at least one closing element  62 , such that motion mechanism  7  is held within inner chamber  32  of jacket  3 ; and at least one bushing  64  for preserving the connection between punch or beater  6  and said motion mechanism  7 . 
     Said closing element  62  is preferably a plate to be secured to a first end of jacket  3 . Said closing element  62  comprises a through hole  622 . In one exemplary but non-limiting embodiment, closing element  62  comprises a plurality of small holes or nozzles (not shown). Said holes are adapted to direct an air jet towards punch or beater  6 . The air, coming from a dedicated supply, flows through the holes and removes sand and dirt from the hammer, thereby preventing early deterioration of the latter. Said holes or nozzles are preferably arranged around a circumference concentrical to hole  622 . Also, said holes or nozzles may be so shaped as to generate an air jet which is angled relative to said axis “Z”, for the purpose of channelling the air towards cylinder  72 . Hammer  2  comprising a closing element as described is particularly suited for application to rotary de-coring machines. 
     By way of non-limiting example, said motion mechanism  7  comprises a head  71  for appropriately directing an air flow, a cylinder  72 , and a beating mass  73  adapted to slide within an inner cavity  722  of the same cylinder  72 . The motion mechanism comprises elastic elements  74 , such as, for example, coil springs. 
     Said elastic elements  74  are adapted to exert a force on motion mechanism  7 , such that said motion mechanism  7  is held in either one of the retracted position and a working position, depending on the action of compressed air, as is known to a man skilled in the art. Said punch or beater  6  is connected to a first end of said cylinder  72 . 
     At said connection, at least one bushing  64  is comprised. 
     Hole  622  comprised in closing element  62  is crossed by said cylinder  72 . Said cylinder  72 , as it moves along said axis “Z” for switching between the retracted position and the working position, slides in said hole  722 . The shape of said hole  622  is such that it prevents any undesired inclination of the cylinder  72  relative to said axis “Z” when hammer  2  is in operation. 
     Said head  71 , located at a second end of said cylinder  72 , is adapted to direct a part of the air into inner cavity  722  of cylinder  72 , so as to put in motion said beating mass  73 . The motion of the beating mass within cylinder  72  generates a vibratory motion of cylinder  72 . Said vibratory motion is transferred to punch or beater  6  as known to a man skilled in the art. 
     The air directed into inner chamber  32  of jacket  3  for moving motion mechanism  7  is exhausted by means of outlet circuit  5  as it exits inner chamber  32  of jacket  3  through an outlet opening  51  comprised in said outlet circuit  5 . 
     The air that has entered inner cavity  722  of cylinder  72  comes out of the same inner cavity  722  through exhaust through holes  724  formed in said cylinder  72 . 
     Motion mechanism  7  will not be described any further herein because it is known to those skilled in the art. 
     In the preferred embodiment, said bushing  64  is made up of two assemblable half-shells, e.g. as shown in  FIG. 2A . Also, said bushing is made of polyester rubber material, e.g. adiprene. 
     In one exemplary but non-limiting embodiment, hammer  2  itself includes a measurement circuit  8  for measuring the oscillation frequency of motion circuit  7 . 
     Describing the construction more in detail, said jacket  3  is made as one monolithic piece, preferably including said connection flange  36 . Said jacket is made by using a mould or chill casting process. 
     In hammer  2  according to the present invention, jacket  3  is made from an aluminium alloy. 
     Said aluminium alloy has a specific weight higher than or equal to 2.60 kg/dm 3 . Said aluminium alloy also has a specific weight lower than or equal to 2.85 kg/dm 3 . 
     This distinctive specific weight range of the alloy according to the present invention is much lower than the value of approx. 7 kg/dm 3  which is typical of cast iron, the latter being the material used in the prior art for making said jacket. This alloy allows a reduction by about two thirds of the total weight of hammer  2 . 
     Said alloy has a percentage in weight of aluminium of at least 83%. 
     Said alloy has a percentage in weight of aluminium lower than 98%. 
     Preferably, the alloy comprises at least one alkaline earth chemical element, e.g. magnesium. 
     Also, the alloy preferably comprises a semiconductor chemical element, e.g. silicon. 
     In the preferred embodiment, in the aluminium alloy employed for making jacket  3  according to the present invention, silicon is used as a semiconductor material and magnesium is used as an alkaline earth element. 
     In one exemplary embodiment of the aluminium alloy, the percentage of silicon is comprised between 4% and 8% and the percentage of magnesium is comprised between 0.2% and 0.8%. 
     The aluminium alloy used for making jacket  3  according to the present invention may comprise one or more metallic elements, e.g. copper, manganese, titanium and zinc. 
     The percentage of the various components may vary depending on physical characteristics, such as the specific weight to be obtained. By way of non-limiting example, a reduction in silicon content will reduce the specific weight of the alloy. On the contrary, the addition of metals to the alloy will increase the specific weight thereof. 
     In the preferred but non-limiting embodiment, the alloy is composed as follows
         Aluminium between 91.87% and 93.1%;   Silicon between 6.5% and 7.5%;   Magnesium between 0.3% and 0.45%;   Titanium between 0.1% and 0.18%.       

     The specific weight of the alloy thus obtained is 2.66 kg/dm 3 . 
     In alternative embodiments, copper is added in percentages comprised between 1% and 1.5%. 
     In general, hammer or vibrator  2  according to the present invention comprises a jacket  3 , which is preferably made of said aluminium alloy, or may be made of cast iron just like traditional prior-art jackets, without however departing from the protection scope of the present invention. Said jacket  3 , as aforementioned, comprises an inlet circuit  4  and an outlet circuit  5 . 
     In the preferred embodiment, said jacket  3  has a substantially cylindrical shape. The embodiment shown in the annexed drawings employs, by way of example, a jacket having a rhomboidal section. 
     Inlet circuit  4  comprises an inlet connector  41  allowing the connection of hammer  2  to a compressed air circuit. 
     Said inlet connector  41  is located at a second end of hammer  2 , and of jacket  3 , opposite to the end where punch or beater  6  is located. 
     Said inlet connector  41  is preferably located in a central region of the base of the cylindrical structure of jacket  3 , as can be seen, for example, in  FIG. 4D . 
     Said outlet circuit  5  comprises an outlet connector  54  for connecting hammer  2  to an air recovery circuit. 
     In the preferred but non-limiting embodiment of hammer  2  according to the present invention, said outlet connector  54  is located at the second end of hammer  2  in proximity to inlet connector  41 . 
     Said outlet connector  54  is preferably also located on the base of the cylindrical structure of jacket  3 , as can be seen, for example, in  FIG. 4D . Said outlet connector is more preferably located in proximity to the outer perimeter of the base of the cylindrical structure of jacket  3 , as shown by way of example in  FIG. 4D . 
     Outlet circuit  5  comprises: an outlet opening  51  formed in cylinder  3 , through which the air comes out upon activation of motion mechanism  7 , and an exit duct  52  extending from said outlet opening  51  up to said second end of hammer  2 , in particular to the second end of jacket  3 . 
     Said outlet opening  51  and exit duct  52  are formed in jacket  3  itself, in particular in the edges of jacket  3  that define inner chamber  32 . Said inner chamber  32  preferably has a circular section, as can be seen, for example, in  FIGS. 2A-2B, 4A and 4B . 
     In particular, said exit duct  52  is incorporated into jacket  3  in an inaccessible manner. 
     Preferably, said exit duct  52  is so shaped as to encircle at least partially, with respect to the plane perpendicular to its longitudinal extension, inner chamber  32  of jacket  3 , thus acting as a cooling circuit for jacket and/or for motion mechanism  7  arranged in said inner chamber  32  of jacket  3 . 
     In general, said exit duct may be so shaped as to follow, at least partially, the curvature of the inner chamber, with respect to the plane perpendicular to its longitudinal extension. 
     In one possible embodiment, the cross-section of said exit duct  52  is shaped like a portion of circular crown. One embodiment of the shape of said exit duct  52  is shown in  FIGS. 4A-4D . 
     In the illustrated embodiment, the radius of curvature of said exit duct is greater than that defined by the inner chamber. 
     In one exemplary embodiment, said exit duct may have a circular or elliptical cross-section, or any shape suitable for encircling, at least partially, the inner chamber of jacket  3 . 
     In embodiments not shown herein, multiple exit ducts are comprised. The exit ducts of said plurality may be arranged symmetrically, e.g. equally spaced, around said inner chamber  32 . 
     In a further embodiment (not shown), said exit duct is a circular hole that only works, for example, as an exit duct, which can however be still integrated into jacket  3 . 
     Preferably, outlet circuit  5  comprises: a first chamber  510  for placing outlet opening  51  in fluidic communication with exit duct  52  by joining them together. Said first chamber  510  may be a closed chamber or a recess formed in proximity to outlet opening  51 , such that it links said outlet opening  51  to said exit duct  52 . In one exemplary and non-limiting embodiment, said first chamber is a tapered duct portion adapted to link the outlet opening to said exit duct. 
     Outlet circuit  5  further comprises an exit chamber  53  that puts exit duct  52  in fluidic communication with outlet connector  54 , e.g. by joining them. Said chamber allows linking said exit duct  52  to outlet connector  54 . In the preferred embodiment, said exit chamber has at least one circular portion that allows fastening, e.g. by means of a thread, the outlet connector to outlet circuit  5 . In an exemplary but non-limiting embodiment, said exit chamber  53  is a tapered duct portion that links said exit duct to outlet connector  54 . 
     Said outlet connector  54  is preferably a discrete element, connected to a hole formed in jacket  3 , e.g. by means of a thread. 
       FIG. 2B  shows one exemplary embodiment of motion mechanism  7 , wherein a man skilled in the art can intuitively appreciate the compressed air flows which enter through inlet circuit  4  in order to move hammer  2  and exit through said outlet circuit  5 . 
     As can be clearly seen, the compressed air supplied to inlet connector  41  enters an intake chamber  42 . Said intake chamber has a variable volume, which depends on the motion of motion mechanism  7  within inner chamber  32  of jacket  3  between the retracted position and the working position. 
     As it enters said intake chamber  42 , the compressed air exerts a thrust on motion mechanism  7 , switching it from the retracted position to the working position. 
     The same compressed air is introduced into inner chamber  722  of cylinder  72  through intake ducts comprised in said head  71 , thus causing the beating mass to oscillate within cylinder  72 , as known to those skilled in the art. 
     The oscillation of motion mechanism  7 , and in particular of beating mass  73 , causes the air to be directed towards outlet circuit  5 . 
     In particular, there is an outlet opening  51  that allows the compressed air to come out of inner chamber  32  of jacket  3 . 
     The air guided by outlet opening  51  is brought, through the exit duct, towards an air recovery circuit. 
     Between an outlet connector, which allows the hammer to be connected to an air recovery circuit (not shown), and exit duct  52  there is said exit chamber  53 . 
     As mentioned above, in a preferred but non-limiting embodiment hammer  2  according to the present invention comprises a measurement circuit  8  for measuring the oscillation frequency of motion mechanism  7 . 
     Said measurement circuit  8  comprises at least one sensor for measuring the oscillation frequency of motion circuit  7 . 
     In one possible embodiment, said measurement circuit  8  is adapted to measure the pressure inside inner chamber  32  of jacket  3 . 
     In a preferred embodiment, said measurement circuit  8  is adapted to detect the sliding motion of beating mass  73  in cylinder  72 . This measurement can be taken directly by means of a position or slide sensor. This measurement can also be taken indirectly by means of a sensor capable of detecting the pressure variations caused by the motion of beating mass  73  in cylinder  72 . The preferred embodiment employs an extensometric sensor capable of detecting the deformation of an electric conductor caused by an alternate air flow ensuing from the sliding motion of beating mass  73  in cylinder  72 . One possible embodiment of said measurement circuit  8 , and of the method for acquiring the measured data, is described, for example, in Italian patent application RN2005A000024. 
     Said measurement circuit  8  comprises a processing circuit (not shown), enclosed in a protection casing  84 , for receiving the electric signals transmitted by said at least one sensor, and a communication line  82  for conducting the electric signals from and/or to said measurement circuit  8 . 
     Said communication line  82  allows said measurement circuit  8  to be connected to an external control circuit (not shown), to which it can communicate the obtained data. 
     The hammer according to the present invention comprises a channel  37 , formed in jacket  3  and leading to the second end of hammer  2 , in particular to the second end of said jacket  3 , near inlet connector  41 . 
     In the exemplary but non-limiting embodiment illustrated herein, said channel  37  has a substantially circular section, as can be seen, for example, in  FIGS. 4C and 4D . 
     Said communication line  82  can be placed in said channel  37 , for the purpose of keeping the whole connection part of the hammer concentrated at the second end thereof. Said channel  37  is preferably incorporated into the walls that define the inner chamber of jacket  3 , in an inaccessible manner. 
     Such an embodiment of jacket  3  allows concentrating the part for connecting the hammer to electric and/or pneumatic circuits by placing it at the second end of hammer  2 . Even more preferably, the connection part is arranged at the base of the cylindrical structure of jacket  3 . Preferably, the shape and structure of the various channels, chambers and ducts formed in said jacket  3  are such that they can be easily obtained by turning or milling. 
     Furthermore, the use of an aluminium alloy allows making said channels, chambers and ducts in significantly shorter times compared to the machining required by cast-iron jackets. 
     In the embodiment shown in the drawings, jacket  3  of hammer  2  according to the present invention comprises a housing  35  formed in the outer surface of jacket  3  itself, the outer profile thereof enclosing measurement circuit  8 , in particular protection casing  84 . 
     The shape of said housing  35  is complementary to the shape of external protection casing  84 , so that the latter can be accommodated therein. 
     In said housing  35  there is at least one fastening portion that allows securing measurement circuit  8  to hammer  2 , in particular to jacket  3 . 
     Measurement circuit  8 , and in particular external protection casing  84 , are fastened to the hammer by means of fasteners such as screws or bolts. 
     Said housing  35  is formed in that portion of cylinder  3  from which connection flange  36  extends. 
     Even more preferably, said housing  35  is formed at the initial flat portion of connection flange  36 , where the same flange  36  begins to protrude from the profile of jacket  3 , as can be seen, for example, in  FIGS. 1A, 1B, 2A, 3 and 4B . 
     Preferably, from said housing  35  channel  37  starts, into which communication line  82  for measurement circuit  8  can be laid. 
     Said channel  37  is even more preferably located in proximity to the outer perimeter of the base of the cylindrical structure of jacket  3 , in particular near the region where flange  36  begins to emerge from the profile of jacket  3 . 
     Furthermore, at said housing  35  jacket  3  comprises a measurement duct  34  through which measurement circuit  8  can take the measurement for determining the oscillation frequency of the motion mechanism. 
     Said duct  34  puts the outside environment in communication with inner chamber  32  of jacket  3 . Near said measurement duct  34  said sensor of measurement circuit  8  is arranged. 
     In the preferred embodiment, said sensor is positioned above said measurement duct  34 , more preferably where channel  34  departs from said housing  35 . 
     In particular, said sensor is arranged on the bottom face of protection casing  84  that encloses the processing circuit, in a suitable aperture through which the air jet generated by the oscillation of beating mass  73  in cylinder  72  can act upon the sensor. 
     The shape of said housing is complementary to said protection casing  84  of measurement circuit  8 . 
     In the preferred embodiment, said housing  35  has a parallelepiped shape, in particular suitable for receiving protection casing  84  of measurement circuit  8 , which also has a parallelepiped profile. 
     Said housing  35  is adapted to envelop at least five faces of protection casing  84  of measurement circuit  8 . 
     As aforementioned, in the illustrated embodiment said jacket  3  has a substantially cylindrical shape with a rhomboidal section, as can be seen, for example, in  FIGS. 4A-4D . 
     The particular aluminium alloy described above provides the entire structure of jacket  3  with more stress resistance and better damping of undesired vibrations. 
     Since the pneumatic and electric connections are all situated in the rear part of the hammer, at the second end thereof, in particular at the second end of jacket  3 , the hammer according to the present invention offers good handling characteristics. 
     Because communication line  82 , e.g. an electric cable, can be connected to an extension cable by means of a connector, the measurement circuit can be installed and removed quickly from hammer  2  according to the present invention. 
     Furthermore, air outlet circuit  5  has been designed for ensuring better cooling of the internal components, in particular of motion mechanism  7 . 
     One particularly important aspect of the present invention concerns measurement circuit  8 , and in particular the sensor, preferably an extensometric sensor, which allows detecting the operating frequency of hammer  2 , in particular the oscillation frequency of the beating mass. 
     In hammer  2  according to the present invention, said measurement circuit  8  is arranged in a suitable housing for protecting it from shocks and preventing it from falling. 
     Said connection flange  36  comprises a plurality of holes  361 , through which fasteners such as socket-head screws can be inserted for removably securing the hammer to a de-coring machine. 
     Said connection flange  36  comprises partition elements  362  that separate the fastening areas. Such partition elements  362  are also shaped in such a way as to abut against heads of fasteners such as screws and bolts compliant with the ISO standards. 
     Hammer or vibrator  2  according to the present invention is very efficient and robust thanks to structures and materials specifically designed and analyzed for the stresses involved. 
     REFERENCE NUMERALS 
     
         
         De-coring vibrator or hammer  2   
         Jacket  3   
         Inner chamber  32   
         Measurement duct  34   
         Housing (sensor)  35   
         Connection flange  36   
         Connection holes  361   
         Partition elements  362   
         Channel (sensor cable)  37   
         Inlet circuit  4   
         Inlet connector  41   
         Intake chamber  42   
         Outlet circuit  5   
         Outlet opening  51   
         First chamber  510   
         Exit duct  52   
         Exit chamber  53   
         Outlet connector  54   
         Punch or beater  6   
         Closing element  62   
         Hole  622   
         Bushing  64   
         Motion mechanism  7   
         Head  71   
         Cylinder  72   
         Inner cavity  722   
         Exhaust holes  724   
         Elastic elements  74   
         Beating mass  73   
         Measurement circuit  8   
         Communication line  82   
         Protection casing  84