DESCRIPTION

The invention relates to a drive unit for drying ovens, used in the manufacturing of bricks also known as "heavy clay industry" .

A drive unit known for brick drying ovens is schematically shown in Figure 1.

The known unit, denoted in whole with reference 11, substantially comprises a parallelepiped metal structure having vertical development 13 housing, inside an upper portion or upper frame 13a, a geared motor 15 and a transmission system 17 comprising a pair of coaxial shafts 17a, 17b located at the opposite sides of the geared motor and equipped with corresponding pinions 19a, 19b at the opposite ends. The pinions 19a, 19b are connected through chain transmissions (not shown) to corresponding return wheels 21a, 21b placed in correspondence to the opposite side flanks 13b, 13c of the structure 13. The return wheels 21a, 21b are supported by shafts rotatably mounted on supports 23a, 23b and bearing, at the opposite end, sprocket wheels 25a, 25b engaging the catenaries (not shown) , vertically extending along the flanks 13b, 13c of the structure 13 up to a lower portion or lower frame 13d in which return sprocket wheels 27a, 27b are provided for said catenaries. According to the known art, the catenaries carry the suspended tray conveyors for the bricks to be processed in the dryer.

The previously described known unit needs a support structure having a considerable size, which develops vertically for a considerable height. As a consequence, the known unit is complex to be built and assembled, and it requires frequent maintenance. Moreover, the high level of couples to be transmitted upon driving the suspended tray conveyors and the size of the wheels on which the catenaries develop frequently cause arising of clearances, the removal of which can involve expensive and complex interventions, besides needing to stop the dryer .

The need to solve the aforesaid problems is therefore felt in the field.

The object of the invention is to provide a drive unit for drying ovens used in the manufacturing of bricks, which does not have the disadvantages of the known art.

This object is achieved through a drive unit as defined in the appended claims.

According to the invention the motor is directly mounted on the catenary shaft; therefore, the kinematic chain from motor to catenaries, which conventionally incorporates a plurality of elements undergoing arising of clearances, is eliminated. Furthermore, according to the invention, the two motors equipping the unit are electronically synchronised.

Advantageously, thanks to adopting the direct transmission between the motor and the corresponding wheel dragging the catenaries, the causes of clearances formation, which afflict the existing units as is well known, are substantially eliminated.

The electronic control of the synchronism between the two drive devices actuated by separate motors allows to adopt reduced size components as well as to limit the unit overall volume, thus making the implementation, the transport and the assembly of the drive unit more economical.

The invention will be described in a preferred embodiment thereof with reference to the accompanying figures in which:

- Figure 1 is a perspective view of a drive unit according to the known art; - Figure 2 is a perspective view of the drive unit according to the invention;

- Figure 3 is an overall view of the actuation device;

- Figure 4 is an exploded view of the device of Figure 3.

With reference to Figure 2 the drive unit for drying ovens used in the manufacturing of bricks according to the invention has been denoted in whole with reference 111.

The unit according to the invention substantially comprises: a support structure 113, a first pair 125a, 125b of substantially coaxial upper sprocket wheels, a second pair 127a, 127b of also substantially coaxial lower sprocket wheels, a first catenary 129a associated to a first sprocket wheel 125a, 127a of said first and second pairs of sprocket wheels and a second catenary 129b associated to a second sprocket wheel 125b, 127b of said first and second pairs of sprocket wheels.

A plurality of suspended tray conveyors 131 for driving the bricks to be processed in the dryer is interposed between the catenaries 129a, 129b. The suspended tray conveyors 131 can be made and associated to the catenaries 129a, 129b according to the known art.

According to the invention the drive unit 111 comprises a pair of actuation electromechanical devices 133a, 133b electronically synchronised with each other, for actuating, respectively, a sprocket wheel associated to a first catenary and a sprocket wheel associated to a second catenary.

In the illustrated example, the actuation devices 133a, 133b are associated to the sprocket wheels 125a, 125b of the upper pair in the structure 113; however, it will also be possible to provide for associating said devices 133a, 133b to the pair of lower sprocket wheels 127a, 127b or also associating a first of said devices to a sprocket wheel of the upper pair and a second device to the sprocket wheel of the lower pair. We now refer to Figures 3 and 4 for describing in more detail the actuation devices 133a, 133b. It is to be noticed that in these figures, since only an actuation device is visible, letters a,b denoting elements associated to different sprocket wheels have been omitted.

Each actuation device 133 comprises an electric geared motor 135 directly engaged in a driven shaft 137 on which the corresponding sprocket wheel 125,127 actuated by said actuation device 133 is fitted.

The actuation device 133 comprises a support 139 defining a fastening flange 141 for the geared motor and a fastening plate 143 for fastening the support 139 to the support structure 113.

The fastening of the geared motor 135 to the flange 141 and of the support 139 to the structure 113 can be done by means of screws or other known means.

Between the fastening surfaces defined in correspondence to the flange 141 and a to the plate 143 a hollow spacer 145 is provided for the passage of the driven shaft 137 on which the sprocket wheel 125 or 127 associated to the geared motor 135 fastened to the support 139 is fitted.

Each geared motor 135 is equipped with a position transducer or encoder 147 associated to a secondary shaft 149 of the geared motor 135. Said secondary shaft 149 is mechanically synchronised with the drive shaft of the geared motor 135 and, consequently, with the driven shaft 137 of the sprocket wheel 125 or 127 associated to the geared motor 135.

The transducer 147 is capable of generating an electrical signal indicative of the position of the secondary shaft 149. The electrical signal generated by each transducer 147 is processed in an electronic control unit. The control unit receives and processes the signals coming from the transducers associated to the two geared motors so as to control the rotation speed of the electric motors of the geared motors and to maintain synchronisation of the position of the sprocket wheels and consequently of the catenaries 129a, 129b and of the suspended tray conveyors 131.

The electric geared motor 135 incorporates an electric motor 151 and a gear reducer 153. The gear reducer 153 is directly driven, i.e. without interposition of belts or transmission chains, from the drive shaft of the electric motor 151 and in turn it transmits directly the motion to the driven shaft 137, that supports the corresponding sprocket wheel 125, 127.

In this way, advantageously, according to the invention, the transmission of the motion from the electric motor 151 to the sprocket wheel 125,127 occurs in the absence of chains or belts .

Again with reference to Figure 2, the structure 113 has a substantially parallelepiped shape and defines an upper portion 113a and a lower portion 113d housing the upper pair of wheels 125a, 125b and the lower pair of wheels 127a, 127b, respectively. The relevant actuation devices 133a, 133b of the (in the illustrated example, upper) wheels are further cantilevered with respect to the side flanks 113b, 113c of the structure 113 thanks to a spacer 145 previously described so as not to obstruct the path of the catenaries 129a, 129b and of the suspended tray conveyors 131. It is to be noticed that, thanks to the invention, the development in height of the structure 113 will be very close to the distance between the pairs of sprocket wheels i.e. to the length of the catenaries and consequently reduced with respect to the known art .

The drive unit as described and illustrated is susceptible to many variants and modifications, all falling within the same inventive principle.