Patent Publication Number: US-9848535-B2

Title: High-security and low-noise agricultural machine

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
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     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
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     THE NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT 
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     INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC OR AS A TEXT FILE VIA THE OFFICE ELECTRONIC FILING SYSTEM (EFS-WEB) 
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     STATEMENT REGARDING PRIOR DISCLOSURES BY THE INVENTOR OR A JOINT INVENTOR 
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     BACKGROUND OF THE INVENTION 
     The present invention relates to a high-security and low-noise agricultural machine. 
     In particular, by low noise it is meant that the machine of the present invention is configured so as to be able to absorb any misalignment or positioning errors of components engaged with each other that can cause strong increases in noise. 
     In particular, the terms “agricultural machine” refer to a machine comprising an engine, generally endothermic internal combustion operating on petrol or Diesel cycle, a clutch, a gearbox, an axle fitted with wheels, a handlebar of motorcycle type, often called “handles” provided with the controls necessary for the various drives, and a power take-off to which a tool to be used is connected. 
     By way of example, if such a tool is a cutter adapted to hoe the soil with motor on the side opposite to the operator, the machine is called “walking tractor”, otherwise, if the tool is a cutting bar with motor on the operator&#39;s side, these machines are called “motor mowers”. 
     Moreover, if the aforesaid handlebar is movable with respect to the power take-off and can rotate up to 180°, allowing the operator to work in a “walking tractor” or “motor mower” configuration, the definition of such machines includes the word “reversible”. 
     Nowadays, for safety reasons, the regulations in force in numerous markets require that if the operator abandons the grip on the handlebars, the machine has to stop, preferably within a limited period of time. 
     This result can be obtained thanks to the presence of a “security” lever, placed on the handlebars, which the operator during use of the relative machine must keep pressed to keep the machine in operation. 
     In fact, this lever is connected to the endothermic engine so that, when released, it causes it to shut down. 
     However, disadvantageously, the shutdown of the engine in case of release of the aforesaid “security” lever does not occur immediately because of the inertia of the engine and of those of the connected kinematic mechanisms. 
     A consequence of this fact is that the machine can continue to move for some time even after releasing the handlebars by the driver, thus creating a potentially dangerous situation for the user. 
     Another limitation of the current solution described above lies in the fact that, after leaving the handlebars, and having therefore begun the shutdown process of the engine, in order to continue the work the operator is forced to restart the shutdown engine. 
     Since most engines of this type have a manual start, the maneuver is not always easy due to the physical effort required. 
     This unfortunately may induce some operators to tamper with the safety device, locking it in the actuated position, thereby avoiding the shutdown of the engine to avoid the burden of the subsequent restart, but consequently significantly reducing the safety of the machine. 
     Another limitation of the configuration currently in use and described above mainly affects the machines provided with gearboxes in oil bath. 
     In fact, in these particular gear machines, the motion it is transmitted via a mechanically actuated clutch through which the entire available power passes. 
     In order to contain the track width of the machine, reducing the transverse dimensions and allowing the execution of special cultivation work, the diameter of this clutch is rather reduced in relation to the power to be transmitted. 
     This limited volume available often makes it mandatory to use dry cone clutches often having a sharp drive, high wear and relevant problems of heat dissipation. 
     In order to reduce the start-up transients, origin of overheating especially with high inertia tools, very stiff springs are often used today which make a mechanical control of the clutch weary and little ergonomic. Furthermore, the manual actuation of a safety lever directly connected to the clutch itself is tiring and unwieldy, having to be maintained for the duration of the work. 
     Finally, wear is often premature, requiring frequent adjustments of the control and increasing risk of malfunctions with potential safety risks. 
     BRIEF SUMMARY OF THE INVENTION 
     To overcome all the drawbacks described above, the Applicant has for a few years marketed a high-security agricultural machine in which, when in use the user leaves the handlebars, the machine stops suddenly while keeping the engine running. 
     Moreover, advantageously, in this machine of the Applicant the actuation of the controls provided at the handlebars only requires little efforts by the user and there is also a safety mechanism that requires a double action for restarting the machine after leaving the handlebars. 
     Now, the object of the Applicant is to further improve this innovative product thereof, addressing the problem of reducing noise and decreasing the stopping time. 
     In fact, in such a machine, as well as in the known ones of the competition, the gear connected to the oil pump is mounted on the shaft of the endothermic engine, and therefore rotates at a high speed. 
     In this condition of high number of revolutions, even minimum misalignments, positioning or geometry errors of the gears can cause large increases in noise. 
     The increase of the mass of the machine and the inertia of the tools connected to it can lengthen the stopping time upon leaving the handlebar, which reduces the level of security. 
     These objects according to the present invention are achieved by providing a low-noise agricultural machine in which the use of a so-called hydromechanical normally disengaged multiple disc clutch is provided, actuated by means of oil under pressure and controlled by two valves with actuating levers connected to each other. The pressurized oil is supplied by a pump, having improved configuration and forming part of the same mechanism, actuated via a molded gear of glass-reinforced polyamide resin technopolymer. The clutch can also act as an automatic brake to reduce the stopping times of both the machine and the tools operated thereby. 
     Further features of the invention are described in the following claims. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
       The features and the advantages of a high-security and low-noise agricultural machine according to the present invention will become apparent from the following exemplary and non-limiting description, made with reference to the accompanying schematic drawings, in which: 
         FIG. 1  is a side elevation view of an agricultural machine; 
         FIG. 2  is a top view of the agricultural machine of  FIG. 1 ; 
         FIG. 3  is a side elevation view of another machine; 
         FIG. 4  is a top view of the agricultural machine of  FIG. 3 ; 
         FIG. 5  is a vertical sectional view of the clutch group belonging to a low-noise agricultural machine according to the present invention; 
         FIG. 5A  is an exploded view of the oil pump group according to the present invention; 
         FIG. 5B  is a perspective partially exploded view of the clutch group of  FIG. 5 ; 
         FIG. 5C  is a sectional view of the clutch group of  FIG. 5  in the evolved embodiment which includes the automatic brake function; 
         FIG. 6  is a horizontal sectional view of the clutch group of  FIG. 5 ; and 
         FIGS. 7 and 8  are schematic views of other components of an agricultural machine according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to the figures, reference numerals  10 ,  10 ′ denote an improved agricultural machine according to the present invention. 
     As shown in  FIGS. 1-4 , such an agricultural machine  10 ,  10 ′ comprises a power delivery engine  11 , at least one axle  12  provided with two wheels  13 , a handlebar  14  and a power take-off  15 . 
     Moreover, the agricultural machine  10 ,  10 ′ comprises a hydromechanical clutch group  20  interposed between engine  11  and the at least one axle  12 , a first “security” lever  16  and a second “clutch” lever  17 . 
     In particular, both said “security”  16  and “clutch”  17  levers are associated to handlebar  14  in a proximal position to that provided for the hands of the user who uses machine  10 ,  10 ′ and are for the control and selective actuation the hydromechanical clutch group  20 . 
     Preferably, the agricultural machine  10 ,  10 ′ according to the present invention also comprises a gearbox  51  interposed between the hydromechanical clutch group  20  and axle  12 , as well as control means  50  of engine  11  and gearbox  51  also placed at handlebar  14 . 
     In particular, the agricultural machine  10 ,  10 ′ may include a tool  20 ,  20 ′ associated with the power take-off  15 . 
     According to two embodiment examples, said tool  20 ,  20 ′ may comprise a cutter  20  adapted to hoe the soil, in this case the agricultural machine  10 ,  10 ′ is a walking tractor  10 , as shown in  FIGS. 1 and 2 , alternatively tool  20 ,  20 ′ may comprise cutter bars  20 ′ and in this case the agricultural machine  10 ,  10 ′ is a motor mower  10 ′, as shown in  FIGS. 3 and 4 . 
     Moreover, advantageously, handlebar  14 , generally of the motorcycle type, can be oriented as desired with respect to the power take-off  15  depending on tool  20 ,  20 ′ to be used. 
     As mentioned at the beginning of the description, the agricultural machine  10 ,  10 ′ comprises a hydromechanical clutch group  20 , which is provided with a first element with outer teeth connected to the driving shaft  23 , hereinafter called “inner group”, and a second bell-shaped element with grooves connected to axle  12 , hereinafter called “outer group”, directly or indirectly depending on the presence or not of gearbox  51 . 
     In particular, such a hydromechanical clutch group  20  comprises a pack of discs  46  facing each other and alternately connected to the inner group and the outer group, in which these discs  46  are movable to come into contact with each other and transmit, when in contact, the motion from the inner group to the outer group. 
     In other words, when discs  46  alternately facing and connected to the inner group and to the outer group come into contact with each other, the motion coming from shaft  23  is transmitted, optionally modified by gearbox  51 , to wheels  13  and to the power take-off of the work tool  20  and  20 ′. 
     As shown in  FIGS. 5 and 5B , the hydromechanical clutch group  20  comprises a movable piston  30  which is hydraulically controllable by the user by acting on the first “security” lever  16  as well as on the second “clutch” lever  17 . 
     In fact, this movable piston  30  is movable between a first raised position, in which discs  46  are uncoupled, and a second lowered position, in which the same discs  46  are coupled to each other. 
     The hydromechanical clutch group  20  is integral with the usually endothermic engine  11 , receives the power through the driving shaft  23 , comprises a flange  21  associated with a portion  22  of the engine, a toothed hub  24  rigidly keyed, preferably by means of a screw  52 , on the driving shaft  23  itself, and a conical bushing  25 , associated with the toothed hub  24 , for dragging a first gear  26 . 
     Coupled to the first gear  26 , a second gear  27  controls an oil pump  28  for introducing pressurized oil into the housing chamber of piston  30 . The oil used for the lubrication of the transmission gears can be put under pressure by the actuation of the mechanism. 
     This oil pump  28  is generally connected to an oil tank, which may also be the same gearbox, via a pipe optionally provided with a replaceable filter and a magnetic plug  30 ′. 
     The oil pump  28  of the present invention, shown in  FIG. 5A , includes a pump body  101  having an 8 shaped seat  102  on one side for housing a drive gear  104  and a driven gear  105  and closed by a plate  103 . 
     On the outside of the pump body  101  on the opposite side of plate  103 , it comprises an outer actuation gear  27  keyed on the drive gear  104  and meshed with the hydromechanical clutch group  20 . 
     Therefore, this outer actuation gear  27  moves the entire pump. 
     In particular, this outer actuation gear  27  is made of synthetic material and is obtained by molding of a glass-reinforced polyamide thermoplastic resin technopolymer. 
     This innovation leads to the advantage of reducing the noise level compared to the common steel gears. 
     In fact, since this gear  27  is mounted on the shaft of the endothermic engine  11 , it revolves at high speed and therefore minimum misalignments, positioning or geometry errors of the teeth can cause a strong increase in the noise level. 
     Advantageously, due to its high elasticity and hysteresis features, the synthetic resin dampens the noise source at the origin. 
     Also, the addition of glass allows the gear to withstand, without decrease of the mechanical features, even if immersed for a long time in the high-temperature oil. 
     It should also be noted that the limited power and the absence of shocks allows effectively sizing the gear and that with an initial investment for the molding equipment, the component does not require any further treatment. 
     The pump body  101  is made of hot stamped leaded steel. 
     Industrial and higher quality benefits are obtained in this way compared to cast iron and greater wear resistance than the aluminum alloy solutions of known embodiments. 
     Moreover, the addition of lead to steel facilitates the processing on machine tool and automatically provides an inherent lubrication during operation. 
     As mentioned above, the internal machining  102  of the seat in the pump body is shaped as an “8” and is edge-free. 
     Such an embodiment, in addition to being easier to execute, prevents any clearance or misalignments from causing interference between gears and seat. 
     Seat  102  is closed by a hardened metal plate  103  so to be a cost-effective and wear resistant component. 
     The pump gears, i.e. the drive  104  and driven  105  gears, are supported only by the pump body and have shafts working overhanging in the pump body  101  and leaning against said plate  108 . 
     In this way, the following two advantages are obtained. 
     It is prevented that the shafts, together with the positioning pins  106 , make the positioning of the pump hyperstatic, a configuration that can cause overheating and seizing, and also in this way, the oil pump is mechanically isolated from the rest of the mechanism to which it is connected only via the synthetic outer gear  27 . 
     Therefore, any faults of the pump cannot cause any damage to the remaining components, making the repair simpler and more economical. 
     Finally, the pump is protected by a replaceable cartridge filter  107  with total flow rate on the suction (see  FIG. 5A ). 
     Preferably, piston  30  is associated with sealing gaskets  31  and there may be at least one preloaded spring  32  which returns piston  30  to a raised initial position in which it does not constrain discs  46  in mutual contact. The same spring or set of springs  112  may be arranged between the clutch discs such as shown in  FIG. 5C . In this configuration, there is an intermediate element  110  consisting of a ring of wear-resistant material, for example hardened steel. When the discs are not constrained in mutual contact, the spring or set of springs  112  pushes disc  111  against ring  110 , braking the loads actuated by the clutch, both the machine and the tool. 
     According to a preferred embodiment, the hydromechanical clutch group  20  comprises a thrust bearing  44  and a disc pusher  45  associated below piston  30 , wherein such a disc pusher  45  is movable under the action of piston  30  to compress the pack of discs  46  alternately connected to the inner group and to the outer group. 
     As shown in  FIG. 5B , the housing chamber of piston  30  is in communication, in addition to the delivery conduit of the pressurized oil, with a drain via a pressure relief valve  37  and two holes  33 ,  34 , shown in  FIG. 6 , intercepted selectively by two rotary or otherwise movable distributors  35 ,  36 . 
     In particular, such two rotary distributors  35 ,  36  are according to the present invention driven in rotation respectively by the first “security” lever  16  and by the second “clutch” lever  17 . 
     In particular, such two rotary distributors  35 ,  36  are associated with springs  38 ,  39  and respectively connected to the second “clutch” lever  17  and the first “security” lever  16  and by two actuating levers  40 ,  41  and flexible cables  42 ,  43 . 
     As seen in  FIG. 6 , the two springs  38 ,  39  return the two rotary distributors  35 ,  36  to an initial position such that a rotary distributor  35 , associated with the second “clutch” lever  17 , occupies hole  33  while the rotary distributor  36  associated with the “security” lever  16 , frees hole  34 . 
     By actuating said “security” lever  16  and the second “clutch” lever  17 , a rotation is imparted to the relative rotary distributors  35 ,  36  in which the rotary distributor  35  associated with the second “clutch” lever  17  frees hole  33 , while the rotary distributor  36 , associated with the “security” lever  16 , occupies hole  34 . 
     The outer group includes a bell  47  integral with axle  12 , a bearing  48  associated with bell  47  and a casing  49  of bearing  48 . 
     Finally, a movable cam  51  is provided, associated with lever  40  connected to the second “clutch” lever  17  of selective engagement of lever  41  connected to the first “security” lever  16 . 
     In particular, this movable cam  51  is shaped in such a way as to make the first “security” lever  16  not operable without first actuating the second “clutch” lever  17 . 
     It is easy to understand the operation of the device object of the invention. 
     The agricultural machine according to the present invention, as described above, before starting the main engine  11  has the following conformation. 
     The oil pump  28  is stopped, and therefore it does not introduce the pressurized oil in the chamber of piston  30  and springs  32 ,  38  and  39  respectively constrain piston  30  in the raised position and the rotary distributors  35 ,  36  and in a position to occupy hole  33  and free hole  34 . 
     In particular, hole  33  associated with the second “clutch” lever  17  is closed while hole  34  associated with the first “security” lever  16  is open. 
     After the starting of engine  11 , the oil pump  28  provides to introduce the pressurized oil in the chamber of piston  30  which, however, does not move from said raised position due to the open hole  34  associated with the first “security” lever  16  from which the oil just introduced comes out. 
     In order to operate the machine, the user must act in succession on the second “clutch” lever  17  and on the first “security” lever  16 . 
     In this condition, the oil pump  28  introduces pressurized oil in the chamber of piston  30  while hole  33  associated with the second “clutch” lever  17  is open and hole  34  associated with the first “security” lever  16  is closed. 
     Even in this condition, therefore, machine  10 ,  10 ′ does not move since the pressurized oil injected into the chamber of piston  30  does not push piston  30  due to the open hole  33  associated with the first “clutch” lever  17  from which the oil just introduced comes out. 
     From this configuration, proceeding to release said first “clutch” lever  17 , preferably gradually as during the normal use of cars and/or motorcycles, also hole  33  is closed, thereby forcing the oil to remain in the chamber of piston  30 . 
     At this point, the pressure in the chamber of piston  30  increases, in particular up to the value allowed by the relief valve  37 , pushing piston  30  to the lowered position and thus making discs  46  come into contact. 
     In this condition, therefore, that is, with “clutch” lever  17  released and “security” lever  16  actuated, the motion is transmitted from engine  11  to wheels  13  and possibly to the tool. 
     In order to actuate gearbox  51  it is sufficient to act on the “clutch” lever  17 , change gear and then release the “clutch” lever  17  itself while keeping the “security” lever  16  actuated. 
     If the user releases, for any reason, the handlebars starting from the condition described above of machine  10 ,  10 ′ in advancement, and thus releases the “security” lever  16 , spring  39  will force a rotation to the relevant rotary distributor  36  to open hole  34 . 
     In such a configuration, the pressurized oil contained in the chamber of piston  30  will flow quickly to the outside from such a hole  34 , thus suddenly reducing the pressure acting on piston  30  which will move to the raised position by the effect of spring  32  or of springs  112 , thus decoupling the contact of discs  46 . 
     In doing so, then, leaving the handlebars completely stops the machine while the engine keeps running. 
     Advantageously, the stopping of the machine is substantially instantaneous independent of the associated inertias, since the engine remains in fact turned on. 
     The configuration shown in  FIG. 5C  reduces the stopping times due to the braking action incorporated in the clutch group, while maintaining a high degree of safety even in the presence of higher inertias. 
     Finally, to proceed to resume work after releasing the handlebars, a dual action is required that involves having to operate the “clutch” lever  17  and then lower the “security” lever  16 . 
     In fact, due to cam  41 , it is not possible to act, with machine stopped, either on or off, on the “security” lever  16  without having previously operated the “clutch” lever  17 . 
     The above controls, i.e. the “security” lever  16  and the “clutch” lever  17 , are advantageously smooth to operate and ergonomic, having to act only on a hydraulic distributor. 
     Since the clutch is in an oil bath, it allows a better heat dissipation and more gradual gear changes without the need for dimensional increases or structural modifications to the machine, which thus maintains all of its features unchanged. 
     In fact, there is no change in the arrangement and logics of the controls compared to other solutions of general use, which minimizes the risks associated with the inadequate training of users. 
     The possibility of obtaining an automatic braking effect of the machine and tool connected to the clutch minimizes the stopping time in case of abandonment of the driving position by the user. 
     Finally, multiple advantages are obtained thanks to the innovative pump group among which the reduction of noise while maintaining the same performance. 
     It has thus been seen that an improved agricultural machine according to the present invention achieves the objects described above. 
     The improved agricultural machine of the present invention thus conceived can be subjected to numerous modifications and variants, all falling within the same inventive concept; moreover, all details may be replaced with technically equivalent elements. In the practice, the materials used as well as their sizes may be whatever, according to the technical requirements.