Patent Publication Number: US-10787327-B2

Title: Multi-bar linkage mechanism based conveyor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Patent Application No. PCT/CN2019/079653, filed on Mar. 26, 2019, which claims the benefit of priority from Chinese Patent Application No. 201810274933.8, filed on Mar. 30, 2018. The contents of the aforementioned application, including any intervening amendments thereto, are incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present invention relates to the technical field of conveyors for transport ships and in particular to a multi-bar linkage mechanism based conveyor. 
     BACKGROUND OF THE PRESENT INVENTION 
     In recent years, inland sand unloading vessels have attracted widespread attention due to their advantages of flexible and quick cargo unloading performance. However, the instability of such vessels also has become increasingly prominent. Furthermore, due to large water coverage and rich waterway resources in China, inland sand unloading vessels have been widely applied and this industry is booming. However, the conveyor boom of a conventional self-unloading vessel may have a length up to 40 m, but it cannot be retracted, resulting in low stability and high safety hazard. For example, since accidents frequently occur in the conventional overhung belt racks, the insurance for belt racks had been refused by insurance companies in China. 
     Therefore, to solve the technical difficulty in retracting conveyor booms, many solutions have been proposed in China, such as stretchable and retractable conveyor booms, rotary conveyor booms and folding conveyor booms. 
     The published Inventive Patent No. 201610594201.8, entitled “SELF-ADAPTIVE INTEGRALLY-OVERTURNED CONVEYOR”, provided a conveying solution in which a two-drum winch and an integral trussed boom are used and the conveyor boom is pulled by the two-drum winch to be folded. This solution solves occupation of the space of the hull to some extent; the integral overturning mode is simpler and more convenient than the folded overturning mode; and during the sand unloading, the boom is higher in safety. However, due to the use of the integral trussed boom that is fixed in length, the conveying distance is not adjustable. Although the integral overturning mode is simpler and more convenient than the folded overturning mode, the overturned conveyor arm is suspended, not firmly fixed, resulting in high safety hazard. 
     The published Inventive Patent No. 201610728114.7, entitled “CONVEYOR WITH STRETCHABLE AND RETRACTABLE CONVEYOR ARM”, provided a solution in which a multi-stage hydraulic cylinder and a scissor fork mechanism are used, and the retraction of the scissor fork mechanism is realized by the multi-stage hydraulic cylinder to thus make the conveyor arm stretchable and retractable. This solution realizes, to some extent, small influence to the balance of the hull by the stretch and retraction of the conveyor arm, large stretchable distance, high stretch and retraction efficiency, stable operation, and high safety. In contrast, compared with the scissor fork mechanism, the multi-bar linkage mechanism is more stable in operation, larger in the stretchable distance, and safer than the multi-stage hydraulic cylinder because the conveyor boom is unfolded in a unit of multi-bar linkage mechanisms; no tensioning mechanism is required; and it is more convenient for production and assembly. 
     SUMMARY OF THE PRESENT INVENTION 
     An objective of the present invention is to provide a multi-bar linkage mechanism based conveyor, to solve problems of self-unloading vessels such as large footprint in an out-of-service state and complex retraction operation, and problems in the prior art such as complex gantry structure, overweight conveyor boom, insufficient length of the conveyor arm, complex mounting and debugging, lack of automatic control, lack of safety guard device, etc., in order to reduce the manufacture and maintenance cost and improve the automation and safety. 
     To solve those technical problems, the present invention provides a multi-bar linkage mechanism based conveyor, comprising a gantry system  1 , a gantry, a set of gantry pulleys, gantry pulleys, a gantry support, a multi-bar linkage mechanism based conveyor boom  2 , a boom support  3 , a first two-drum winch  4 , a roller unit  5 , a second two-drum winch  6 , a hull  7  and an automatic control system. The multi-bar linkage mechanism based conveyor boom  2  comprises multi-bar linkage mechanisms  201  and hydraulic cylinders  202 , and is in a composite structure of carbon fibers and carbon steel. The multi-bar linkage mechanism based conveyor boom  2  is articulated with the boom support  3  to facilitate adjustment of the conveying angle of the multi-bar linkage mechanism based conveyor boom  2 . The multi-bar linkage mechanism based conveyor boom  2  comprises a plurality of multi-bar linkage mechanisms  201  each having a set of pulleys  203 , and each two adjacent multi-bar linkage mechanisms  201  are powered by one hydraulic cylinder  202 . To retract the multi-bar linkage mechanism based conveyor boom  2 , the adjacent multi-bar linkage mechanisms  201  are stretched or retracted one by one, and each two adjacent multi-bar linkage mechanisms  201  are driven by one hydraulic cylinder  202 . Thus, the conveyor boom moves. As the movement principle of the multi-bar linkage mechanisms  201 , the multi-bar linkage mechanism  201  comprises, on a single side, eight bars among which: a first bar  11  is fixed, the second bar  12  is pushed by a hydraulic cylinder  202 , the fourth bar  14  is driven by the second bar  12  so that the
         third bar  13  moves together, and the fifth bar  15  is driven by the second bar  12  and the third bar  13  so that the seventh bar  17  and the sixth bar  16  that is directly articulated with the second bar  12  move together, and in this way, the eighth bar  18  is driven to move horizontally. Accordingly, the multi-bar linkage mechanism based conveyor boom  2  can be stretched smoothly.   The multi-bar linkage mechanism based conveyor boom  2  comprises multi-bar linkage mechanisms  201 , hydraulic cylinders  202  and pulleys  203 . The first two-drum winch  4  is connected to the pulleys  203  on the multi-bar linkage mechanism based conveyor boom  2  via a steel wire rope and by a set of gantry pulleys  101  arranged on top of the gantry. A tension sensor  19  is arranged at an end of the steel wire rope. When tension information obtained by the tension sensor  19  indicates a risk value, the whole conveyor may be controlled by the automatic control system to stop operating. The second two-drum winch  6  is connected to a gantry pulley  102  arranged at an upper end of the gantry via a steel wire rope. A tension sensor  19  is arranged at an end of the steel wire rope. The stability of the whole gantry system  1  is determined through the tension sensor  19 , to avoid the loss of stability of the whole system. Both an angle of pulling of the whole conveyor and the stability of the gantry system  1  are controlled by the automatic control system, by analyzing the information from the tension sensor  19 . In this way, the automatic control and the safety monitoring are realized. Each multi-bar linkage mechanism  201 , serving as an operating unit, of the multi-bar linkage mechanism based conveyor boom  2  can send a signal to a corresponding hydraulic cylinder  202  by the control system, to determine the stretch distance of the multi-bar linkage mechanism based conveyor boom  2 , thus to stretch the multi-bar linkage mechanisms  201  one by one.   In the gantry system  1 , the set of gantry pulleys comprises a set of front pulleys that are connected to the pulleys  203  on the multi-bar linkage mechanism based conveyor boom  2  via a steel wire rope, and a set of rear pulleys that are connected to the first two-drum winch  4  via a steel wire rope. The second two-drum winch  6  is connected to a gantry pulley  102  arranged at an upper end of the gantry via a steel wire rope. The gantry is connected to the multi-bar linkage mechanism based conveyor boom  2  via a steel wire rope, and the gantry and the multi-bar linkage mechanism based conveyor boom  2  together form a stable and substantially triangular structure. The gantry is articulated to a gantry support and is able to rotate around the gantry support by a certain angle. The multi-bar linkage mechanism based conveyor boom  2  is articulated with the boom support  3 . In the gantry system  1 , the steel wire ropes separately connected to the first two-drum winch  4  and the second two-drum winch  6  are each equipped with a tension sensor  19 , information from a respective tension sensor  19  is transmitted to the automatic control system by the stretch distance of the multi-bar linkage mechanism based conveyor boom  2 , and then the starting/stopping of the first two-drum winch  4 , the second two-drum winch  6  and the hydraulic cylinder  202  is controlled by the automatic control system according to the safety range of this tension. The gantry system  1 , the boom support  3 , the first two-drum winch  4  and the second two-drum winch  6  are all mounted on a deck of a hull  7 . The gantry can be pulled by the steel wire rope to rotate, by controlling the second two-drum winch  6  to start or stop, so that the multi-bar linkage mechanism based conveyor boom  2  can rotate by an angle ranging from −20° to +20°.   The roller unit  5  comprises upper bearing rollers  8 , lower return rollers  9  and reversing rollers  10 . The upper bearing rollers  8  are uniformly mounted on the cross-bar on the surface of the boom. The lower return rollers  9  are mounted on the cross-bar on the bottom of the boom. The reversing rollers  10  are mounted at a forefront end of the multi-bar linkage mechanism based conveyor boom  2 . Automatic tensioning can be realized since the multi-bar linkage mechanisms  201  of the multi-bar linkage mechanism based conveyor boom  2  are stretched. No tensioning device is required, so that the overall structure is more concise.   The multi-bar linkage mechanism based conveyor boom  2  is simple in structure. Each multi-bar linkage mechanism  201  is connected by a bolt. By obtaining stressed deformation information of each multi-bar linkage mechanism  201  from the tension sensor  19  by using the automatic control system, the multi-bar linkage mechanism based conveyor boom  2  is controlled and monitored precisely. Accordingly, risk factors can be found in time. This can reduce the fault probability and ensure the operating efficiency of the conveyor because the operators can carry out repairs in advance. Furthermore, the whole conveyor is automatically controlled by a programmable control system.   Compared with the prior art, the multi-bar linkage mechanism based conveyor designed according to the above technical solution has the following beneficial effects. Compared with the integral trussed boom and the scissor fork mechanism used in the prior art, the multi-bar linkage mechanism based conveyor boom  2  has the following advantages: first, the overall structure is simple and the structural modularization is convenient for production and assembly; second, the deformation under load is low;   third, the conveying length is increased; and fourth, high safety and better stretch and retraction performance are provided. Since a tension sensor  19  is arranged at an end of the steel wire rope, when the multi-bar linkage mechanism based conveyor boom  2  is to be retracted, automatic control can be realized by the automatic control system. The operating difficulty of the operators is greatly decreased, and the safety in operating the device is significantly improved. The multi-bar linkage mechanism based conveyor boom  2  will not occupy the space of the hull  7 . The multi-bar linkage mechanism based conveyor boom  2  is in a composite structure of carbon fibers and common carbon steel. The connection of the multi-bar linkage mechanisms in units and by a set of bolts is convenient for transportation and detachment. This greatly reduces the weight of the multi-bar linkage mechanism based conveyor boom  2  and enhances the controllability of the multi-bar linkage mechanism based conveyor boom  2 . Due to the multi-bar linkage mechanisms  201 , the torsional strength and the stability of the conveyor are improved. This greatly increases the length of the multi-bar linkage mechanism based conveyor boom  2  and greatly increases the conveying range. In the multi-bar linkage mechanism based conveyor, by changing the retraction of the conveyor boom to horizontal retraction, the operation is simpler and more convenient than the integral overturning mode and the folded overturning mode; and during the sand unloading, the boom is higher in safety. Furthermore, no tensioning device is required. This reduces loads on the boom. Moreover, it is easy to realize automatic adjustment of the tension and deviation of the conveyor belt, high retraction efficiency, more reliable safety factor, low maintenance and use costs, etc.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an overall structure diagram of a multi-bar linkage mechanism based conveyor; 
         FIG. 2  is a partial structure diagram of a multi-bar linkage mechanism based conveyor boom; 
         FIG. 3  is a structure diagram of a multi-bar linkage mechanism; and 
         FIG. 4  is a schematic view of a multi-bar linkage mechanism based conveyor, in the retracted state, in which:
           1 : gantry system;     101 : gantry pulley arranged on top of the gantry;     102 : gantry pulley arranged at an upper end of the gantry     2 : multi-bar linkage mechanism based conveyor boom;     201 : multi-bar linkage mechanism;     202 : hydraulic cylinder;     203 : pulley;     231 : pulley sheave;     232 : connecting rod;     3 : boom support;     4 : first two-drum winch;     5 : roller unit;     6 : second two-drum winch;     7 : hull;     8 : upper bearing roller;     9 : lower return roller;     901 : connection handle;     10 : reversing roller;     11 : first bar;     12 : second bar;     13 : third bar;     14 : fourth bar;     15 : fifth bar;     16 : sixth bar;     17 : seventh bar;     18 : eighth bar; and     19 : tension sensor.       

     
    
    
     DETAILED DESCRIPTION OF THE PRESENT INVENTION 
     The present invention will be further described below with reference to the accompanying drawings by specific embodiments. 
     As shown in  FIG. 1 , in the gantry system  1 , the set of gantry pulleys comprises a set of front pulleys that are connected to the multi-bar linkage mechanism based conveyor boom  2  via a steel wire rope, and a set of rear pulleys that are connected to the first two-drum winch  4  via a steel wire rope. The second two-drum winch  6  is connected to a gantry pulley  102  arranged at an upper end of the gantry via a steel wire rope. The gantry is connected to set of pulleys  203  on the multi-bar linkage mechanism  201  based conveyor boom  2  via a steel wire rope, and the gantry and the multi-bar linkage mechanism based conveyor boom  2  together form a stable and substantially triangular structure. The gantry is articulated to a gantry support and is able to rotate around the gantry support by a certain angle. The multi-bar linkage mechanism based conveyor boom  2  is articulated with the boom support  3 . In the gantry system  1 , the steel wire ropes separately connected to the first two-drum winch  4  and the second two-drum winch  6  are each equipped with a tension sensor  19 , information from a respective tension sensor  19  is transmitted to the automatic control system by the stretch distance of the multi-bar linkage mechanism based conveyor boom  2 , and then the starting/stopping of the first two-drum winch  4 , the second two-drum winch  6  and the hydraulic cylinder  202  is controlled by the automatic control system according to the safety range of this tension. The gantry system  1 , the boom support  3 , the first two-drum winch  4  and the second two-drum winch  6  are all mounted on a deck of a hull  7 . The gantry can be pulled by the steel wire rope to rotate, by controlling the second two-drum winch  6  to start or stop, so that the multi-bar linkage mechanism based conveyor boom  2  can rotate by an angle ranging from −20° to +20°. 
     As shown in  FIG. 2 , the multi-bar linkage mechanism based conveyor boom  2  comprises multi-bar linkage mechanisms  201  and hydraulic cylinders  202 . Each two adjacent multi-bar linkage mechanisms  201  are powered by one hydraulic cylinder  202 . To retract the multi-bar linkage mechanism based conveyor boom  2 , the adjacent multi-bar linkage mechanisms  201  are stretched or retracted one by one. The first two-drum winch  4  is connected to the pulleys  203  on the multi-bar linkage mechanism based conveyor boom  2  via a steel wire rope and by a set of gantry pulleys  101  arranged on top of the gantry. A tension sensor  19  is arranged at an end of the steel wire rope. The pulling of the whole conveyor is controlled by the automatic control system. The second two-drum winch  6  is connected to a gantry pulley  102  arranged at an upper end of the gantry via a steel wire rope. A tension sensor  19  is arranged at an end of the steel wire rope. The stability of the whole gantry system  1  is determined through the tension sensor  19 . Both an angle of pulling of the whole conveyor and the stability of the gantry system  1  are controlled by the automatic control system. Each multi-bar linkage mechanism  201 , serving as an operating unit, of the multi-bar linkage mechanism based conveyor boom  2  can send a signal to a hydraulic cylinder  202  by the control system, to determine the stretch distance of the multi-bar linkage mechanism based conveyor boom  2 . The roller unit  5  comprises upper bearing rollers  8 , lower return rollers  9  and reversing rollers  10 . The upper bearing rollers  8  are uniformly mounted on the cross-bar on the surface of the boom. The lower return rollers  9  are mounted on the cross-bar on the bottom of the boom. The reversing rollers  10  are mounted at a forefront end of the conveyor boom  2 . Automatic tensioning can be realized since the multi-bar linkage mechanisms  201  of the multi-bar linkage mechanism based conveyor boom  2  are stretched. No tensioning device is required, so that the overall structure is more concise. 
     With reference to  FIG. 3 , the multi-bar linkage mechanism  201  comprises, on a single side, eight bars among which: a first bar  11  is fixed, two ends of a second bar  12  are articulated with the first bar  11 , a fifth bar  15  and a sixth bar  16 , the second bar  12  is articulated with a fourth bar  14  at a position that is 43%-44% of its whole length, two ends of a third bar  13  are articulated with the first bar  11 , the fourth bar  14  and a seventh bar  17 , two ends of the seventh bar  17  are articulated with the third bar  13 , the fourth bar  14  and an eighth bar  18 , the seventh bar  17  is articulated with the fifth bar  15  at a position that is 56%-57% of its whole length, two ends of the sixth bar  16  are articulated with the second bar  12 , the fifth bar  15  and the eighth bar  18 , and the eighth bar  18  can move. To realize the movement of the eighth bar  18 , the second bar  12  is pushed by a hydraulic cylinder  202 , the fourth bar  14  is driven by the second bar  12  so that the third bar  13  moves together, and the fifth bar  15  is driven by the second bar  12  and the third bar  13  so that the seventh bar  17  and the sixth bar  16  that is directly articulated with the second bar  12  move together, and in this way, the eighth bar  18  is driven to move horizontally. 
     In another embodiment of the present invention, the multi-bar linkage mechanism based conveyor boom  2  may be completely in a structure of common carbon steel. 
     In another embodiment of the present invention, the set of pulleys on the multi-bar linkage mechanism based conveyor boom  2  may include an even number of sets of pulleys of various types, which are dispersed one before the other. 
     The embodiment of the present invention has the following operating principle. The multi-bar linkage mechanism based conveyor boom  2  is stretched by the hydraulic system in each multi-bar linkage mechanism  201 , simultaneously the first two-drum winch  4  and the second two-drum winch  6  are started to tension the steel wire rope, the steel wire rope for the set of pulleys on the gantry is tensioned to a set pre-tensioning force, the hydraulic cylinder  202  reaches a set position, and the hydraulic cylinder  202 , the first two-drum winch  4  and the second two-drum winch  6  all automatically stop operating. The gantry is pulled by the second two-drum winch  6  by a steel wire rope, and the gantry and the multi-bar linkage mechanism based conveyor boom  2  together form a stable and substantially triangular structure. In this way, a stable structure is formed. Therefore, the conveying angle of the multi-bar linkage mechanism based conveyor boom  2  can be adjusted by pulling the gantry by the second two-drum winch  6 . During the sand unloading, the second two-drum winch  6  may play a role of fixing the conveyor by the steel wire rope. The steel wire ropes connected to the first two-drum winch  4  and the second two-drum winch  6  are each equipped, at an end thereof, with a tension sensor  19 . When the tension becomes abnormal or when the multi-bar linkage mechanism based conveyor boom  2  runs under overloads, the tension sensor  19  on the steel wire rope will give an alarm and send a stop signal to the control system, so as to ensure the safety operation of the conveyor. The present invention is not limited to the above implementations. All multi-bar conveyors obtained by using the same structures as or similar structures to those described in the above embodiments of the present invention shall be within the protection scope of the present invention.