Abstract:
A process and apparatus for controlling the cleaning of a grille for filtering cooling air of a radiator particularly of engines, in which the cooling air is forced with the aid of a ventilation system and in which the cleaning is effected by blowing with the aid of at least jet cleaner assembly sweeping tangentially the surface of the grille. The jet cleaner assembly is controlled as a function of a parameter connected to the regime or the flow of the ventilation system and/or each time or the same time as the regime or flow falls to or below a predetermined level.

Description:
FIELD OF THE INVENTION 
     The present invention relates to the cleaning of grilles for filtering the cooling air of radiators of gaseous and liquid fluids and more particularly of radiators for various engines working in dusty air loaded with solid particles suspended in the air. 
     BACKGROUND OF THE INVENTION 
     A typical application of the invention is for example cleaning the grilles of oil and water radiators of movable devices, such as loaders, compactors or graders for the treatment of waste or the compacting of soil. 
     The radiators of these devices are provided with grilles for filtering air that cools the radiators and which is forced through said grilles. 
     These are pierced with a large number of holes or passages of small dimensions through which the dust and solid particles in suspension in the air cannot pass, thereby more or less greatly obstructing the grilles. 
     Periodically, it is necessary to clean the surface of these filtering grilles, so as to eliminate the impurities which are held and retained thereon and various systems for cleaning these filtration grilles are already known, by brushing or blowing, whose principle is well known. 
     These cleaning systems are either difficult or even impossible to mount, because they are bulky, particularly on loaders, or complicated in design, use and maintenance. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to provide a simple and effective means adapted to clean periodically these grilles in an automatic and effective manner. 
     To this end, the invention has for its object a process for controlling the cleaning of a grille for filtering the cooling air of a radiator, particularly of engines, through which the cooling air is forced by means of a ventilation system, the cleaning being carried out by blowing with the aid of at least one blower sweeping tangentially the surface of the grille, characterized in that it consists in controlling said blower as a function of a parameter connected to the regime or the flow of the ventilation system and/or each time or at the same time as said regime or flow falls to a predetermined level or below this latter. 
     According to an embodiment of the above process, more particularly adapted for engines of the loader type or the like, said parameter is a signal generated upon passage of the speed selector into a reverse movement position, this signal being adapted to be, in the case in which the engine is provided with a backup signal, the actuation current of this latter. 
     The invention also has for its object a device for practicing this process, adapted for an engine in which the cooling air is forced by the aid of a ventilation system, said device comprising a filtration grille, on at least one side of which is disposed a tangential blower and reserve of compressed air, connected to said blower via an electromechanical control device, characterized in that the filtration grille has a transverse cross-section of undulant profile, said blower having, at one of the ends of each groove in the form of a conduit formed by the grille, a jet or the like for sweeping the groove, and in that said control device of the blower is connected to means actuated as a function of the regime or of the flow of the ventilation system when said regime or flow is reduced to zero or nearly zero. 
     According to one application of the invention to engines, of the loader type or the like, provided or not with a backup signal and whose ventilation system is actuated by the engine motor, said means actuated as a function of the regime of the ventilation system are constituted by a timer activating for a predetermined time a relay for supplying an electrovalve permitting the sending of air under pressure into said blower, said timer being actuated by a signal generated by the speed selector of the engine, such that the blower will be operated each time the selector is actuated for reverse motion, which is to say concomitantly with the minimum regime of said ventilation system, the engine motor being decelerated. 
     Preferably, the blower is actuated only if the air pressure in said reservoir is above a predetermined level. 
     The device of the engine thus ensures cleaning both automatically and effectively, on the one hand thanks to the undulant configuration of the filtration grille, which increases the filtration surface and, on the other hand, by the placement of the jets of the blower at one end of the U-shaped grooves of the grille, thereby ensuring powerful tangential sweeping over all the surface of the groove and along all its length. 
     Such sweeping is systematically controlled as soon as, when the engine is actuated, the forced air ventilation regime for cooling of the radiator or radiators, with water or oil or any other liquid or gaseous fluid, is sufficiently low and particular when it is minimal, which is the case particularly at each manipulation of the speed change selector to move to reverse motion, the engine motor being necessarily decelerated and hence the ventilation system, connected to the motor regime of the engine, also operating at a minimum. 
     In the case of the use of the invention with engines of the loader type or the like, whose ventilation system is actuated independently of the motor of the engine, the control of the blower will be triggered for example from a preprogrammed control or not, periodic or not, or the ventilation system. This control of the ventilation system can consist, for example, of temporarily feathering, for about several seconds, the blades of the ventilation system, said feathering giving rise to actuation of said blower. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other characteristics and advantages will appear from the description which follows, of an embodiment of the process of the invention, which description is given solely by way of example and with respect to the accompanying drawings, in which: 
     FIG. 1 is a fragmentary schematic view of an engine of the loader type; 
     FIG. 2 is a fragmentary perspective view of a filtration grille according to the invention; 
     FIG. 3 is a diagram of a preferred embodiment of the device of the invention applied to an engine provided with a sonic backup alarm; and 
     FIG. 4 is a diagram of the control of a blower from an electrovalve, itself controlled from the actuating motor of the ventilating system. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In FIG. 1, there is shown schematically and partially the forward portion of a loader and more precisely the front upper portion of the cowl  1  of the motor, on the upper surface, substantially horizontal, of which open, at the front end, louvers for the introduction of air, covered by an air filtration grille  2  according to the invention. 
     There are downstream louvers for the grille  3 , for the outlet of air. 
     Below the cowl  1 , between the two grilles  2 ,  3 , is located the radiator  4  for cooling water or any other type of fluid necessary for the engine. 
     The incoming air  5  is drawn in and forced through the grille  2 , then from the radiator  4  and finally to the grille  3  to be discharged at  6 , by means of a ventilation system symbolically indicated at  7 , generally driven by the engine motor. 
     Referring to FIGS. 1 and 2, the grille  2  for filtration of the incoming air  5  is constituted by a metallic plate  8  pierced or opened by a large number of small holes  9  and bent so as to delimit the parallel grooves  10  in the form of conduits. 
     The plate  8  which thus has an undulant transverse profile, is fixed by any suitable means on a rectangular metallic frame  11 , itself mounted on the cowl  1 . 
     The grooves  10  are oriented in the direction of movement of the engine and are swept by air under pressure from a blower  12  disposed transversely to the grooves  10  at their end turned toward the rear of the cowl  1 . 
     The blower  12  is integrated into the rear edge of the frame  11  and comprises a conduit (not shown) integrated into the frame and connected by a conduit  13  (FIG. 1) to a source of compressed air, typically the pressurized reserve with which engines of this type are conventionally provided. 
     Facing the inlet of each groove  10 , the blower  12  is provided with jets  14  or the like. 
     At the forward end, the frame  11  is open to let the sweeping air escape, directed downwardly by a deflecting plate  15  fixed to the frame. 
     FIG. 3 is a diagram of the control means of the blower  12  according to the invention. 
     The blower  12  is connected by the conduit  13  to the pressurized air reservoir  16  of the engine, via an electrovalve controlled by a relay  18  itself actuated by a timer  19 . 
     The timer  19  is connected, via a pressure contact  20  deriving from the conduit  13 , a conductor  21  connecting the speed selector  22  of the engine to a sonic backup alarm  23  with which the latter is provided. 
     In normal operation of the engine, cooling air  5  drawn through the radiator  4  of the motor gives rise to a pressure on the external surface of the air filtration grill  8 , leading to blocking of this latter by dust and various debris. During change to reverse movement operation of the motor, the drop in the motor regime gives rise practically to the disappearance of this pressure, thereby permitting, during this short time, to proceed automatically to cleaning of the grille by the device of the invention. 
     When the speed selector  22  is actuated for reverse motion, for safety reasons, a current is delivered to the sonic backup alarm  23  by the conductor  21 . 
     This current, called a control current, is used according to the invention to actuate the timer  19  which itself ensures the current supply of the relay  18  for ten seconds for example, this duration being of course adjustable. This relay  18  delivers, during the same time lapse, the supply current to the electrovalve  17  which opens the passage of air under pressure toward the blower  12 . 
     The jets, holes or nozzles  14 , which are calibrated, send along the axes of the grooves  10  a powerful jet  24  sweeping tangentially all the surface of the grooves over all their length. This jet is even more efficacious because it is produced precisely at the moment in which the pressure holding the particles against the grille, occasioned by the forced air flow of the fan  7 , is at a minimum, because the regime of this latter is directly connected to that of the motor, necessarily slowed down during speed change. 
     Each time the reverse drive of the engine is over, so will be automatically the pressure detected by the pressure contact  20 , sufficient in the reservoir  16 . 
     The pressure contact  20  avoids too frequent use which would empty the reserve of pressurized air. To a certain extent, it is optional and can be omitted if the reservoir  16  is sufficiently large. 
     The device of the invention is not only effective, but economical as to compressed air. 
     The parameter controlling the actuation of the electrovalve  17  is in this case the passage toward reverse movement of the engine. Under the usual conditions of use of these engines, the reverse movements are sufficiently numerous to ensure suitable cleaning. 
     It is to be noted that in the absence of a backup alarm  23 , the speed selector  22  of the engine can be provided with means generating a signal each time there is change into reverse movement, this signal being sent to the pressure contact  20 . 
     The above parameter is connected indirectly to the regime of fan  7 , because the changes to reverse movement and to the minimum regime of the fan, are concomitant. 
     The parameter controlling the electrovalve  17  can be a parameter connected more directly to the regime of the fan  7 . 
     Thus the electrovalve  17  could be controlled each time said regime reaches, when slowing down, a predetermined value or exceeds that predetermined value, for example with the aid of means indicating the speed of rotation of the fan, connected to the electrovalve. 
     This could be operated also in the case in which the fan  7  is not driven by the engine motor, but by an independent motor, which could be hydraulic or electrical for example. 
     FIG. 4 shows such a control of the electrovalve  17 ′ supplied with air from the reservoir  16 . To this end, a timer T controls for example periodically the momentary stopping of the motor M (electrical or hydraulic for example) for driving the fan  7 . Each time the regime of the motor M, measured by a speed detector V, reaches when decreasing a predetermined threshold, which is adjustable, said detector V generates a signal controlling the actuation of said electrovalve  17 ′, this latter being closed when the regime of the motor M again rises above said predetermined threshold. 
     Moreover, the electrovalve  17  of FIG. 3 could be controlled from a signal generated by the passage of the speed selector  22  to reverse movement, the signal controlling the actuator of the electrovalve  17 , as well as the momentary stopping of the drive means of said fan  7 . In this case, the control of the electrovalve  17  is retarded relative to the stopping control of the fan such that the electrovalve will be triggered only after the fan regime has reached a sufficiently low level, so as to take account of the inertia of the system. 
     Again in the case in which the fan  7  is not driven by the engine motor but by an independent motor, the blower  12  could be triggered for example from a preprogrammed control or not, periodical or not, of the ventilation system. 
     This control of the ventilation system could consist for example of temporary feathering, for the order of several seconds, of the blades of the fan  7 , said feathering giving rise to the actuation of said blower. 
     This control of the ventilation system could also take place by cutting the electrical or hydraulic supply of the motor means by which the system is constituted by a fan or a turbine electrically or hydraulically controlled. 
     As another control parameter of the electrovalve  17 , let also be taken the control of the injection pump of the motor, the fan  7  being driven by this same motor. 
     Thus in this case, the regime of the fan is directly connected to the control of said injection pump. 
     The orientation of the grooves  10  relative to the cowl  1  could be different, as well as the emplacement of the blower along one of the sides of the frame  11 . 
     If the grooves  10  have a great length, it is possible that there could be a blower at each end, the two operating alternately. 
     Finally, the invention is obviously not limited to the embodiments shown and described above, but on the contrary covers all variance, both as to shape, dimensions and arrangements of the grooves, the frame and the blower for the filtration grille  2 , as well as the emplacement of this latter on the engine according to the nature of the emplacement of the radiator to be provided and the type of air impulsion, by suction or propulsion. 
     Similarly, modifications can be envisaged as to the actuating means of the blower or blowers, as well as the control parameter connected to the speed of rotation of the fan for forcing the cooling air.