A STREET SWEEPER MACHINE WITH TRASH PICK-UP AND TRANSPORT CAPABILITIES

Abstract: A street sweeper machine is provided for picking up and transporting trash comprising a frame (2) having a main longitudinal dimension and engaging front (4a,4b) and rear (5a,5b) wheels, a driver's cab (3), motor members (44,48), a trash bin (6), a roll brush (11) located between said wheels and having a symmetry axis (12) parallel to a surface to be cleaned and transverse to said longitudinal dimension, a trash conveyor (10) conveying trash from said roll brush (11) to said bin (6), and steering members (22) engaging all of said wheels to make all of them steerable and adapted to define an intersect point (13) for the axes of said wheels in cornering which lies proximate a continuation of said symmetry axis (12) of said roll brush (11).

Description: This invention relates to a street sweeper machine with trash pick-up and transport capabilities defined in the preamble of the accompanying Claim 1 and disclosed in WO-A-8 401 401 and in EP-A-0 189 371. As is known, some street sweeper machines designed for large surface sweeping, such as urban surfaces, are configured with a driver's cab, a tank containing water to be delivered to a surface being swept to damp it preparatory to sweeping proper so as to keep down dust, a bin for collecting trash picked up from the ground, brushes in contact with the ground surface, and a trash conveyor operative to receive trash from the brushes and discharge them into the trash bin. The brushes usually include both side and front brushes of frustrum or cup-like shape which are laid with their axis of rotation transverse to a surface to be swept, and a cylindrical or roll brush having its axis of rotation substantially parallel to said surface in a substantially center area of the machine. The side and front brushes direct trash to the roll brush, aid the latter redirects it to said trash conveyor. A street sweeper with two side brushes and a cylindrical brush is shown in the application WO-A-8 401 401. In this sweeper a framework is supported by a pair of rear wheels and a single steerable front wheel is provided. The Patentee has made machines of the aforesaid type wherein the trash conveyor is located between the trash bin and the driver's cab, and extends vertically upwards from an area close to the ground surface in order to pick up trash more effectively, thereby the machine is split into two discrete regions: a forward region comprising the driver's cab, the engine, and steerig front drive wheels, and a rearward region mostly engaged by the trash bin. The trash conveyor is formed with plural moving paddles carried on chains and driven thereby, the chains being driven by sprocket wheels which are in turn driven by a specially provided motor. The machines of the type just described have shown their operability and are quite compact in size for a given load capacity and throughput. It has been found, however, in actual use that it is sometimes, desirable to increase the machine load capacity an dimensions, and more generally its overall performance. This because dumping sites and trash incinerators tend to be established at increasingly longer distances from cities, on account of the growing concern for pollution problems brought about of necessity by dumping sites and incinerators. Likewise, trash conversion plants for reclaiming power or any reusable substances contained therein tend to be established further away from dwelling areas. As a result, the trash bin should be of sufficient capacity to not only provide for continued operation for many hours a day, but also so that frequent round trips to dumping sites or trash incinerator plants are not required. Ideally such a machine should be able to operate for a whole day to pick up trash and only reach the dumping site or incinerator, which may be several kilometers away, at the end of the daily work cycle. Actual tests carried out by the Patentee have shown that machines of the type as aforesaid cannot be provided by merely enlarging prior machines or their trash bins. In particular street sweeper machines, in order to carry out with adequate accuracy the basic trash picking up operations, are in the first place required to reach quickly and accurately all the areas to be swept clean, while avoiding the many obstructions encountered. Large size machines cannot move with sufficient nimbleness among the obstructions presented by cities unless a large steering angle is provided for their steering wheels. However, this appears to be irreconcilable with the sweeping operation: with a large steering angle, the paths travelled by the font and side brushes which direct the trash material leave over the ground path marks which do not overlap the path of the substantially centrally located cylindrical or roll brush. It follows that not only are unswept areas left over the ground but also areas with dust and trash build-ups, that is with trash gathered by the side and front brushes which the roll brush has failed to pick up. Further, if the steering angle of the wheels is increased, the roll brush, which has its axis of rotation substantially parallel to the ground and perpendicular to the main longitudinal dimension of the machine, may be dragged along paths which involve increased cross skidding thereof over the ground, that is paths having a large component parallel to the axis of the roll brush. Such skidding movements tend to cause the bristles comprising the roll brush to be flexed towards the axis direction. It follows that, in tight cornering, the roll brush becomes distorted and flattens along the axis direction, thereby no longer being able to perform correctly its basic funtion of ground sweeping and above all of directing the trash material to the vertical conveyor. It may be also appreciated that such distortion of the roll brush brings about increased wear of the same and the need for replacement at frequent intervals. In order to increase the steering angle it is known to make front wheels and rear wheels all steering wheels. For example the application EP-A-0 189 371 discloses a snow removal vehicle with a roll brush and with steering members adapted to dispose all the steering wheels, during cornering, with their axes of rotation convergent on a steering centre close to the band defined by generatrix lines of the roll brushes. But this technical solution does not overcome the cited drawbacks. With large size machines, maneuverability is also affected by lack of direct visibility by the driver of the areas being worked upon. The use of a variety of viewing mirrors can only partly remedy this problem. It should be noted that if the engine of prior machines is rated higher to afford adequate speed during the trips to dumping sites or incinerators, the net result is again an inadequate piece of machinery with poor street maneuverability. In fact, in order to carry out the various street sweeping operations, powerplants are required which can operate for long periods at very low speeds, and which can operate at such very low speeds smoothly with no jerky response to controls so that all the movements can be controlled in an easy and accurate manner. By enlarging prior machines and increasing their power, additional drawbacks are introduced, such as a higher vertical reach of the conveyor where the trash bin is made exceedingly large. This in order to ensure adequate filling of the bin, even when the latter has been filled almost to the brim. It follows that the chains holding the trash conveyor paddles, which are to nearly span the full height of the bin from an area proximate the ground surface and wich are subjected to significant stresses, cannot always be tensioned as it is desirable. Slack tensioning results in reduced effectiveness of the conveyor. Owing to such drawbacks, street sweeping machines of the above mentioned type are currently made in relatively small sizes and cannot meet the above-noted work demands without involving significant breaks lasting upward of several hours for transporting the picked up trash a long distance at the end of the working cycle. This being the situation, the technical aim underlying this invention is to devise a machine of the type noted above and of a large size, whereby the cited drawbacks can be substantially overcome. Within this technical task, it is an important object of this invention to provide a machine which, while having large dimensions, a large load capacity, and adequate travel speed capabilities over roads and highways, is efficient, easily maneuvered, and convenient to control during the street sweeping operations. The technical task set forth above and the object specified are substantially achieved by a street sweeping machine as described in Claim 1. Preferred embodiments of the invention are specified in Claims 2 to 12. The invention's features and advantages will become more clearly apparent from the following description of a preferred embodiment of a machine according to the invention, to be taken in conjuction with the accompanying drawings, where: Figure 1 is a partly cut-away side elevation view; Figure 2 shows the paths travelled by the bushes of the machine under full steering lock; Figure 3 is a partly cut-away rear view showing schematically the machine of Figure 1; Figure 4 shows the fluid-operated devices aid kinematic elements provided for steering the wheels, seen partly from below; Figure 5 is a longitudinal section through the upper portion of the vertical trash conveyor shown in Figure 1; and Figure 6 shows schematically some control members. With reference to the drawing views, the street sweeping machine of this invention is generally indicated at 1. Briefly and with specific reference to Figure 1, the machine 1 comprises a frame 2 rigid at the top with a driver's cab 3 and at the bottom with two front wheels 4a and 4b, in this specific instance drive wheels, and two rear wheels 5a and 5b. Designated a are the left-hand side wheels and b the right-hand side wheels, relatively to the forward travel direction. Each wheel has, of course, an axis, or axis of rotation, and in steering said axes would converge together. The frame 2 has a main longitudinal dimension, and this longitudinal dimension coincides in practice with the direction of straight ahead travel of the machine 1. In parallel with this dimension there are two longitudinal side frames, a right one and a left one, at which the wheels are located. The rear portion of the frame 2 is engaged with a trash bin 6 on the interior whereof there are provided, at an elevated location, a bank of filters 7 and a first portion 8a of a suction duct placed downstream of the filter bank 7. A second portion 8b of the suction duct connects the first portion 8a to a suction turbine 9 rigid with the frame 2. The filter bank 7 comprises a series of modular elements 7a which extend substantially throughout the length of the bin 6 and over a reduced height. The modular elements can be assembled to and disassembled from their seats separately. A shaker 7b, formed by a rotary rod to which a continuous eccentric elevation is mounted, is located beneath the modular elements 7a and intermittently hits in its rotary movements the filters shaking dust off them. A trash conveyor 10 extends in a substantially vertical direction forwardly of the bin 6 substantially throughout the width of the frame 2, and is in communication with the bin 6 through a top opening formed in the bin. Downwardly of the bin 6 and at a slightly rearward location from the conveyor 10, there is the roll brush 11. The roll brush 11 has an axis of symmetry 12, which is also its axis of rotation lying parallel to the surface to be swept and orthogonally to the main longitudinal dimension of the frame 2 of the machine 1. A rigid housing 15 holds the roll brush 11 and is supported at each side frame by a pair of oscillatable parallel elements 16 pivoted to the frame so as to form an articulated quadrilateral. A water tank 17 is provided between the conveyor 10 and the suction turbine 9, and forwardly of the roll brush 11 there are arranged, laterally of the frame, two counter-rotating cup-like brushes 18a for directing the trash toward the roll brush 11. A third position-adjustable brush 18b is located forwardly of the frame 2. As shown in Figure 2, the machine 1 is advantageously equipped with a four-wheel steering, and the front wheel and rear wheel steerings are originally coordinated such that the steering center 13 of the machine 1, resulting from the intersection of the straight lines coinciding with the axes of rotation of all the wheels lies proximate a continuation of the symmetry axis 12 of the roll brush 11. Since, the roll brush 11, while being located substantially inwardly of the machine 1, is not normally located intermediate the front and rear wheels, the steering angles alpha and beta of the front wheels 4a, 4b respectively, are different from the steering angles delta and gamma, respectively, of the rear wheels 5a, 5b. Also shown in Figure 2 are the paths 13a, 14a travelled in cornering by one end 11a of the roll brush 11 with either steering by all wheels and the steering center 13 proximate the axis 12, or with steering by just the front wheels and hence a second steering center 14 aligned to the rear axle. It may be appreciated that whereas in the former case the swept band of the roll brush 11 overlaps the areas swept by the cup-like brushes 18a, in the latter case a strip is left which is swept by neither the cup-like brushes 18 nor the roll brush 11. Lastly, Figure 2 shows the two minimum steering radii 13b, 14b the former, as provided by this invention, being clearly smaller than the latter. The steering members 22 for the front drive wheels 4a, 4b and the rear wheels 5a, 5b are shown in Figure 4. That figure shows that in the driver's cab 3 there may be provided two simultaneous control stations, affording dual control features, or alternative stations, depending on road traffic regulations, comprising steering wheels alternately 19a and right 19b. Between the two steering wheels, at a center location in the driver's cab 3, a dashboard 20 is provided which can be turned to orientations facing the left steering wheel 19a or right steering wheel 19b as desired. In the instance of dual mode controls, selection of the right or left control stations will depend on viewing range afforded by either for manoeuvering. Within the dashboard 20 a control knob 20a with a key 20b is provided to set normal front steering or coordinate steering on all the wheels. Two angle drives 21 connect the steering wheels 19a and 19b and to steering members 22 which comprise, first of all, an oil-operated steering system 23, known per se, which is supplied oil under pressure by a unit 26 including a reservoir 27, filter 28, and pump 29. The oil-operated steering system 23 control, the front wheel 4a via kinematic elements or linkages 24 which are lead to first levers 24a engaging the wheel 4a directly. One end of said first levers 24a is engaged with the rod of a first piston 30 movable inside a first oil-operated cylinder 31. The first cylinder 31 is in oil communication via two first lines 32 to a similar second oil-operated cylinder 33 having a second piston 34 whose rod is engaged by second levers 35a with the rear wheel 5a. The first 31 and second 33 cylinders form with the first piping 32 a first fluid-operated device 25 which is closed and rigidly interlocked with the first levers 24a, as well as adapted to provide rigid coordination of the steering of the wheels 4a and 5a placed on the same longitudinal side of the frame 2, in the example shown the left-hand side, engaged by the wheels 4a, 5a. In practice, the elements 31, 32, 33 form a rigid "hydraulic bar"; for each movement of the piston 30 in the first cylinder 31 there must strictly correspond a movement of the second piston 34 in the second cylinder 33. Thus, the diaphragm represented by the trash conveyor 10 is avoided which, as set forth above, has expediently a width dimension approximating that of the frame 2, while stably interconnecting the front and rear wheels. Also provided are front transfer elements 36 and rear transfer elements 37, all of a mechanical nature, which coordinate the steering actions of the front wheel 4b and the rear wheel 5b, respectively. The front transfer elements 36 extend from the first levers 24a and are led to third levers 36a engaged directly with the left front wheel 4b. The rear transfer elements 37 extend from the second levers 35a and are led to fourth levers 37a engaged directly with the left rear wheel 5b. A second fluid-operated device 40 is arranged to connect to the oil-operated steering system 23 and extends along the right side of the frame 2 opposedly from the side engaged by the hydraulic bar. This second fluid-operated device 40 comprises a third cylinder 38 engaged with the third levers 36a of the front wheel 4b, a fourth cylinder 39 engaged with the fourth levers 37a of the rear wheel 5b, and second piping 41 interconnecting the cylinders 38 and 39. A lock assembly 42, advantageously comprising air-operated members, is operative to lock the rear transfer elements 37 when the steering system for the rear wheels 5a and 5b is to be deactivated, such as on the occasion of trips at relatively high speeds. The compressed air is supplied to the lock assembly 42 from a first electric air distributor 43. With the rear wheels locked, a second electric distributor 41a is operated to act via the pipes 41 and 32 to deactivate the second and fourth cylinders 33 and 39. It should be also pointed out that Figure 4 shows a third electric distributor 32a connected in the first piping 32 to control the oil flow therethrough. The machine 1 is driven forward by means of motive members comprising two motors as shown in Figure 6. A first gasoline engine 44 enables fast forward driving of the machine 1 via connections generally indicated with both full and dash lines and comprising a drive 45 having a set of gear wheels 45a which receive their motion from a gearbox or speed transmission 46 and transfer it to a differential gear 47. For slow speed forward travel, the machine 1 uses a second hydraulically operated motor 48 operated from a pump 49 driven off the gearbox 46 with the top speed gear engaged. In this case, the connections shown by the dash-and-dot lines in Figure 6 are engaged and the drive 45 shown in dash lines and including the gear wheels 45a is disengaged. Figures 1 and 5 show then that the vertical trash conveyor 10 comprises a driveshaft 50 at an upper location and a layshaft 51 at a lower location. The driveshaft 50 is mounted on two self-aligning bearings 52, in turn carried on two movable plates 53. The movable plates 53 can move vertically across the walls 54 of the conveyor 10 and are pulled upwards by tensioning members. The latter comprise, at each wall 54, a lever 55, a trunnion 56 welded to the wall 54 and supporting the lever, and a first spring 57 engaging one end of the lever 55. Also provided is a cam 58 which urges the respective movable plate 53 and is stabilized by a second spring 59. In actual practice, the cam 58 is used to effect the initial or resisting basic positioning and the lever 55 to adjust for any slackening. The driveshaft 50 is hollow and carries at one end a pin shaft 60a of a small hydraulic motor 60, held abutting the driveshaft 50 by a screw link 61. It follows that there is no direct connection between the movable plate 53 and the hydraulic motor 60. A key 62 prevents rotation of the hydraulic motor 60, while allowing it to move on the driveshaft 50 being lowered and raised. A pair of first sprocket wheels 63 are fast with the driveshaft 50 proximate its ends and carry two chains 64 which are also trained around second sprocket wheels 65 engaged on the layshaft 51. Paddles 10a are attached to the chains 64 for receiving trash material from the roll brush 11 and discharging it into the bin 6. The machine 1 operates as follows. At the operator's choice, either all the wheels or just the front wheels can be made to steer. Steering by all wheels is contemplated, however, for sweeping operations. In summary, the steering members 22 act, via the oil-operated steering system 23, on the front wheel 4a, whence via the first fluid-operated device 25 tie command to steer is transferred to the rear wheel 5a. Mechanical transfer elements 36, 37 then coordinate the movements of the front wheel 4a to the front wheel 4b, and of the rear wheel 5a to the rear wheel 5b. The second fluid-operated device 40 is finally operated to interlink the front wheel 4b and rear wheel 5b. The fluid-operated devices 25 and 40 and transfer elements 36, 37 engage the wheels via levers 24a, 35a, 36a, 37a, and it is the size of the latter that determines the steering angle for each wheel. Once the position of the roll brush 11 is known relative to the wheels, said levers are sized, according to the invention, to provide steering angles alpha, beta, gamma, and delta effective to cause the wheel axes to converge to a point close to the straight line defined by the symmetry axis 12 of the roll brush 11. The steering center formed by the intersection of the wheel axes shall then be more or less close to the frame 2 of the machine 1 depending on the extent of the steering action. During the sweeping operations, the most appropriate control station is used in relation to the direct visual monitoring of the sweeping operations, and the machine 1 will use for its propulsion the hydraulic motor 48 which ensures flexibility and simplicity in steering at very low speeds. On the other hand, during road trips to the dumping sites or incinerators, the gasoline engine 44 is used, and steering on the rear wheels can be locked. Even where the bin 6 is of a large size, the introduction of trash into the bin can take place efficiently by means of the conveyor 10, whose construction is unconditioned by the presence of mechanical connections between the front and rear wheels, and whose chains 64 are kept all times taut because the motor 60 follows any oscillations of the chain driveshaft 50. It should be also noted that the position of the roll brush 11 is at all times maintained correctly not only because the steering center of the machine 1 is at all times proximate the continuation of the roll brush axis but also because the contact with the ground is always exactly calibrated due to the articulated quadrilateral formed by the oscillatable elements 16. The presence of said articulated quadrilateral also allows the roll brush 11 to be raised while travelling on the road, using the motor 44. The invention achieves important advantages In fact, maneuverability of the sweeper machine is high despite its large size. The steering method used for the wheels, with different steering angles of the front wheels from those of the rear wheels arid the steering center proximate the roll brush axis, affords proper skidding of the roll brush over the ground even in tight cornering maneuvers. It follows that the roll brush 11 undergoes no distortion in a direction parallel to its axis, such as would tend to damage it and reduce its efficiency and durability. Further, there are no unswept areas and no trash traces are left over the ground. The steering devices enployed enable coordinated steering on all the wheels in an accurate manner, overcoming the diaphragm created by the presence of the trash conveyor. In fact the connection piping for the fluid-operated steering devices takes up little space and can be routed through long twisting paths without difficulty. Propulsion of the machine with two different motors meets the requirement for high travel speeds where required and low, easily controlled speeds during the sweeping work. Note should be taken of that the first gasoline engine need not be stopped with the second motor in operation, and that in order to vary the drive to the drive wheels it is sufficient to engage or disengage mechanical members.

Claims: A street sweeper machine (1) for picking up and transporting trash, comprising: a frame (2) having a main longitudinal dimension and engaging at least front wheels (4a, 4b) and rear wheels (5a, 5b) whose axes of rotation converge together in cornering, a driver's cab (3), motor members (44, 48), a trash bin (6), a roll brush (11) having a symmetry axis (12) substantially parallel to a surface to be swept and lying transversely of said longitudinal dimension, a trash conveyor (10) adapted to convey trash from said roll brush (11) to said bin (6), and characterized in that it comprises steering members (22) engaging all of said wheels (4a, 4b, 5a, 5b) to make them all steering wheels, and adapted in cornering to dispose said wheels (4a, 4b, 5a, 5b) with their axes of rotation convergent on a steering center (13) proximate a continuation of said symmetry axis (12) of said roll brush (11). A machine according to Claim 1, wherein said steering members (22) are adapted to define steering angles for said front wheels (4a, 4b) and steering angles for said rear wheels (5a, 5b) which differ from each other, said roll brush (11) being offset from an intermediate position to said front wheels (4a, 4b) and said rear wheels (5a, 5b). A machine according to Claim 1, wherein said steering members (22) comprise, for steering said front (4a, 4b) and rear (5a, 5b) wheels, at least one fluid-operated device (25) having cylinders (31, 33) engaging at least one said front wheel (4a) and at least one said rear wheel (5a), and having piping (32) for said cylinders (31, 33) engaging a side frame of said frame (2) parallel to said longitudinal dimension, said frame (2) being through-penetrated, transversely of said longitudinal dimension, by said trash conveyor (10). A machine according to Claim 3, wherein said steering members (22) comprise: first and third levers (24a, 36a) selectively engaging said front wheels (4a, 4b), second and fourth levers (35a, 37a) selectively engaging said rear wheels (5a, 5b), an oil-operated steering system (23) engaging on cornering, via said first levers (24a) and alternatively said third levers (36a), one of said front wheels (4a, 4b), a first fluid-operated device (25) having first and second fluid-operated cylinders (31, 33) identical with each other and engaging, via said levers, respectively one of said front wheels (4a, 4b) and one of said rear wheels (5a, 5b), and having first piping (32) interconnecting said cylinders (31, 33) and extending along said one side frame of said frame (2), and first and second transfer elements (36, 37) of a mechanical nature engaging together said front wheels (4a, 4b) and said rear wheels (5a, 5b). A machine according to Claim 4, wherein aid steering members (22) further comprise a second fluid-operated device (40) engaging one of said front wheels (4a, 4b) and one of said rear wheels (5a, 5b) selected to be free from said first fluid-operated device (25), said second fluid-operated device comprising second piping (41) extending along a side frame of said frame (2) free of said first piping (32). A machine according to Claim 3, wherein said steering members (22) comprise a lock assembly (42) controllable in operation to lock said rear wheels (5a, 5b) against steering, said lock assembly (42) being arranged to make the machine stable during road travelling. A machine according to Claim 3, wherein to control said steering members (22) there are provided, in said driver's cab (3), two steering wheels (19a, 19b) laid side by side along a transverse direction to said longitudinal dimension, and a dashboard (20) intermediate to said steering wheels (19a, 19b) and pivotable toward the same. A machine according to Claim 1, wherein there are provided a first gasoline engine (44) for fast travelling and a second hydraulically operated motor (48) for slow forward movement of the machine at work. A machine according to Claim 8, wherein to operate said second motor (48) there are provided a pump (49) and a drive (45) intervening between said first engine (44) and said pump (49) and being controllable to disengage. A machine according to Claim 3, wherein said trash conveyor (10) engaging said frame (2) transversely comprises transport paddles (10a), chains (64) engaging said paddles (10a), a driveshaft (50) and a layshaft (51) engaging sprocket wheels (63, 65), said chains (64) being trained arround said sprocket wheels (63, 65), a drive motor (60) for rotating said driveshaft (50) carried directly on said driveshaft (50), and tensioning members (55-59) of said driveshaft (50), movable plates (53) being provided to support said shaft. A machine according to Claim 10, wherein said tensioning members (55-59) comprise, at each end of said driveshaft (50), a lever (55), a fixed trunnion (56) to which said lever (55) is pivoted, and a first spring (57) acting on said lever (55), with the latter active on one said movable plate (53), and further comprise a cam (58) adapted to force said movable plate (53) and a second spring (59) for locating said cam (58). A machine according to Claim 10, wherein said roll brush (11) is positioned between said trash conveyor (10) and said rear wheels (5a, 5b), and wherein for supporting the same, oscillatable elements (16) are provided which are journalled on said frame (2) and arranged to form an articulated quadrilateral.

Inventors: ZONI, SERGIO
Applicants: DULEVO INTERNATIONAL S.P.A.
Application year: 1988
Main classification: E01H1
IPC codes: E01H1, B62D7