Patent Publication Number: US-10767338-B2

Title: Hydraulic apparatus for excavators and construction equipment in general

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the U.S. National Phase Application of PCT/EP2016/050428, filed Jan. 12, 2016, which claims priority from IT PD2015A000005, filed Jan. 15, 2015, the contents of which applications are incorporated herein by reference in their entireties for all purposes. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to a hydraulic apparatus, such as a rotating crusher, comprising a hydraulic motor actuated via a power circuit linkable to the main hydraulic circuit of an earth-moving equipment, such as an excavator or an earth-moving equipment in general. 
     Among the accessories attachable to the arms of excavators and similar construction equipments, it is known to use milling apparatuses, typically known as milling heads or rotating crushers, formed by a pair of drums provided with a row of teeth. 
     Apparatuses of this type have the advantage of having increased versatility and efficiency, and are typically used in the field of facilities for constructing tunnels or, more generally, in the field of construction works for communication routes and in cutting blocks of stone. 
     An example of this type of apparatus is described in U.S. Pat. No. 6,626,500, which relates to a rotating cutter comprising a shell on which two rotating drums are supported. The drums are mounted on the same shaft, which is set in rotation by a hydraulic motor actuated by means of an oil supply provided by the construction equipment itself. The apparatus can be fixed to the arm of an excavator via a linking connector in such a way that the operator can displace and orient the cutter as desired so as to excavate in the required position. 
     One of the problems linked to rotating cutters is that rotor blockages often occur, typically because the variety of the material in terms of hardness and resistance to crushing is never homogeneous, just as the surface to be crushed is not homogeneous. This means that the energy needed for dealing with this material differs between the rotors, creating a greater energy requirement from the rotor which is subjected to higher stress. In these cases, it may actually be found that the construction equipment cannot provide a sufficient torque to keep the drums rotating, partly because they are both meshed to the same rotating shaft and because the torque supplied by the construction equipment is thus inevitably divided into two equal parts. 
     Therefore, in cases where only one of the two drums comes into contact with harder material, there is actually an inefficient torque distribution. 
     Further, since the two drums are rigidly interconnected by means of the transmission shaft, there is a significant transmission of stresses and vibrations both to the cutting structure and to the arm of the construction equipment, leading to low precision in the positioning of the arm and thus in the cutting operation, and to potential damage to the arm of the supporting equipment. 
     A further example of crushing apparatus is disclosed in U.S. Pat. No. 7,604,301, relating to grinder blender comprising two cylindrical drums operated by a respective hydraulic motor. A hydraulic fluid supply line receives hydraulic fluid under pressure from the rotary hydraulic manifold, and discharges the hydraulic fluid to a flow divider. The flow divider supplies hydraulic fluid equally to the two motors through respective high pressure lines. 
     Therefore, the technical problem addressed by the present invention is to provide a hydraulic apparatus which makes it possible to overcome the drawbacks mentioned above in relation to the known prior art. 
     This problem is solved by the hydraulic apparatus according to the invention. 
     BRIEF SUMMARY OF THE INVENTION 
     Preferred features of the invention are defined in the dependent claims. 
     The present invention has some major advantages. The main advantage is that the apparatus according to the present invention makes it possible to reduce the number of blockages that can occur during excavating operations and to limit the strains transmitted to the arm of the supporting equipment. 
     Further, the apparatus according to the present invention makes it possible to achieve better and more efficient exploitation of the torque provided via the hydraulic circuit of the construction equipment. 
     In addition, the apparatus according to the present invention makes it possible to limit the transmission of stresses, in particular lateral stresses, and vibrations to the arm of the construction equipment to which it is linked, considerably improving operating precision. 
     This is particularly advantageous in earth-moving equipments in which the arms are dimensioned and designed for withstanding frontal stresses and not lateral stresses. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further advantages, features and uses of the present invention will be apparent from the following detailed description of some embodiments, provided in an exemplary and non-restrictive manner. Reference is made to the figures of the accompanying drawings, in which: 
         FIG. 1  is a perspective view of a hydraulic apparatus according to the present invention; 
         FIG. 2  is a partially sectional front view of the apparatus of  FIG. 1 ; 
         FIGS. 3A and 3B  are a partial front view and a partial perspective view respectively, both partially sectional, of the apparatus according to the present invention, and schematically illustrate the operation thereof; 
         FIG. 4  is a perspective view of a flow divider device belonging to the apparatus of  FIG. 1 ; 
         FIG. 5  is a partially sectional front view of a second embodiment of the apparatus according to the present invention; 
         FIGS. 6A and 6B  are two views, one from above and one from below, of the apparatus of  FIG. 5 ; 
         FIG. 7  is a perspective view of a flow divider device belonging to the apparatus of  FIG. 5 ; 
         FIG. 8  is a partially sectional front view of the flow divider device of  FIG. 7 ; and 
         FIGS. 9A and 9B  are two perspective views showing the flow divider device of  FIG. 7  without a particular flywheel and showing this flywheel as a separate component. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring initially to  FIG. 1 , a hydraulic apparatus for an excavator or more generally for a construction equipment, also referred to in the following as a supporting equipment, is denoted as a whole by reference numeral  100 . As will be made clearer in the following, the hydraulic apparatus  100  is suitable for mounting on a movable arm of the excavator via a linking plate  5  or other equivalent attachment means. 
     Preferably, linking plate  5 , or other coupling element, is configured such that the hydraulic apparatus  100  is rigidly connected to the movable arm. 
     The apparatus  100  comprises an outer shell  1 , which defines a support structure on which a pair of drums  2  are rotatably supported. 
     Each drum  2  supports a plurality of teeth  20  which make it possible to grind the material as a result of the rotation of the drums  2 . 
     Now also referring to  FIG. 2 , the apparatus according to the present invention further comprises a pair of hydraulic motors  3 , each arranged for the movement of an associated drum  2 . Preferably, the hydraulic motors  3  are mutually independent, meaning that each one is supplied with a particular oil supply, provided via a suitable supply duct  31 , in such a way that the speed and torque provided by the rotation of one motor are independent of those of the other motor. 
     In a preferred embodiment, the support structure  1  comprises an enlarged portion  10 , at which the linking plate  5  is located, and an end portion  11 , opposite the plate  5  and linked to the enlarged portion  10  by a tapered segment. 
     Preferably, the motors  3  are positioned at the end portion  11 , having an axis of rotation X perpendicular to a longitudinal extension direction of the support structure, substantially coincident with a removal direction of the excavator arm to which the plate  5  is fixed. 
     In a preferred embodiment, the drums  2  are directly connected to the respective motors  3  so as to also be rotatable about the axis of rotation X. 
     The apparatus according to the present invention further comprises a rotating flow divider device  4  which makes it possible to divide a supply of operative fluid into two parts, each to be directed to one of the two motors  3 . Preferably, the flow divider  4  comprises at least two rotating elements  402 , described in greater detail in the following with reference to  FIG. 4 , which are coaxial and mutually rotationally engaged. 
     The rotating flow divider device  4  is for example of the type marketed by Casappa under the trade name Polaris or described in U.S. Pat. No. 2,291,578. 
     In greater detail, the flow divider device  4  comprises an inlet  41  for receiving the flow of operative fluid provided by the construction equipment and a pair of outlets  42 , connected to the ducts  31  for providing the operative fluid, which is suitably subdivided, to each of the hydraulic motors  3 , as is also shown in  FIGS. 3A and 3B . 
     In a preferred embodiment, the device  4  is housed in the enlarged portion  10  of the support structure  1  and preferably receives a supply of fluid from the construction equipment by means of a duct  32  which can be linked to the hydraulic circuit thereof. 
     A first example of a flow divider device  4  is shown in  FIG. 4  and is geared. More specifically, in the present embodiment, the rotating elements  402  are formed by gears. 
     In this type of flow divider device  4 , there are at least two pairs  40  of gears  401 ,  402 , each pair  40  being associated to a particular outlet  42  of the divider. 
     Preferably, the flow divider device  4  comprises a further pair of gears  44  associated to the inlet  41 . 
     The operative liquid enters the divider at the inlet  41 , setting the pair of gears  44  in rotation as a result of passing therebetween. Further, by way of a channelling system  47 , the operative fluid reaches the outlets  42 , passing between the gears  401  and  402  of the respective pairs of gears. 
     Thus, the gears used in the device  4  are actually formed so as to be able to work as gear pumps. 
     In the present embodiment, a gear  402  of one pair is meshed to the same shaft  43  as a corresponding gear  402  of the other pairs. 
     In this way, the gears rotate in a mutually engaged manner and at the same speed. For a better understanding of the operation of the divider device as applied to the present invention, it should be borne in mind that, as described above, the power requirement in each of the two motors may vary depending on the specific operating conditions in the two drums, and it should also be noted that in these types of pumps, the supply remains virtually constant for a fixed number of rotations, whilst the power varies approximately linearly with the pressure. 
     When a lower power is required in one of the two drums, there is thus a resulting lower pressure requirement at the outlet associated to the motor of this drum, and therefore a greater pressure will be available for the other gear and the associated outlet, thus making a greater power available to the other drum. 
     This therefore makes it possible to exploit the pressure provided by the construction equipment in an optimum manner. 
     In other words, the energy not used by the other drum is not dissipated as heat, but used in the other pair of gears by way of the linking shaft. 
     Now referring to  FIGS. 5 to 9 , a variant of the apparatus according to the present invention will now be described. 
     This variant comprises a flow divider device  4 ′ which comprises a pair of auxiliary hydraulic motors  40 ′ instead of the geared device described above. 
     Therefore, in this case, the rotating elements are formed by an outlet shaft  402 ′ of each of the hydraulic motors  40 ′. 
     The hydraulic motors  40 ′ are supplied with the same supply via lines  32 A and  32 B connected to the duct  32  which provides the operative fluid from the construction equipment. 
     Meanwhile, the outlet of the auxiliary hydraulic motors  40 ′ is linked to the hydraulic motors  3 . 
     The outlet shafts of the two motors are further interlinked by means of a connection element  45  which causes them to be rotationally engaged. 
     The system thus provided therefore acts as a flow divider in the same way as the device  4  described in relation to the present embodiment. 
     Preferably, the connection element  45  is formed from a flywheel which is locked to the two shafts  402 ′ by means of keys. 
     This solution is found to be particularly advantageous in that, at the moment when the grinding drums  20  start to slow down and potentially become blocked as a result of the friction of the processed material, the inertial effect of the flywheel  45  comes into effect, preventing the hydraulic motors  40 ′ from slowing down and actually increasing the grinding force, preventing the two drums from being blocked. 
     The invention thus solves the problem addressed whilst simultaneously leading to a plurality of advantages, including a lower frequency of blocking in the apparatus and a better use of the available power. If necessary, the flow divider device can even operate as a receiving divider having an instigator divider, solving the problem of continuous blockage which occurs when these apparatuses are used. 
     Further, comprising two independent motors, and thus not having a central linking spindle, provides a major advantage in that the stress transmitted by the apparatus to the arm of the excavator or of the supporting equipment is cushioned. 
     By comparison with solutions using a spindle for linking the rotors, the use of a flow and supply divider actually provides a damping effect in the transmission of the transverse stress to the arm, greatly reducing the problems in the arm of the equipment.