Method for controlling filling rate in filling machine

A method for controlling the rate of filling bottles as they are moved by a rotary table, in which position indicating devices are attached to the pistons which move the filling nozzles up and down in the vertical direction, the position indicating devices are detected just before the bottles are discharged from the rotary table to determine whether filling of the bottles is completed by means of two piston position detecting devices A and B which devices are circumferentially spaced-apart so as to define an included angle .theta. of 10.degree. to 30.degree. with respect to the center of the rotary table, and the rotation speed of the rotary table is increased or decreased so that the proportion of completely filled bottles detected by the first or leading detecting device A during each rotation of the rotary table is less than 100% but the proportion of completely filled bottles detected by the second or trailing detecting device B during each rotation of the rotary table is 100%.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a method for controlling the filling rate 
in a filling machine. More specifically, the present invention relates to 
a filling method in which bottles are fed into a rotary table and a 
predetermined amount of a substance is filled in each bottle while the 
rotary table makes one rotation, said method being characterized by the 
features that just before withdrawing the filled bottles from the rotary 
table, the proportion of completely filled bottles is detected by two 
filling completion detecting devices defining a central angle .theta. of 
10.degree. to 30.degree. with respect to the center of the rotary table 
and the rotation speed of the rotary table is increased or decreased based 
on the results of the detections. 
2. Description of the Prior Art 
According to conventional methods for filling liquids into bottles, bottles 
are fed onto a rotary table, filling nozzles are inserted into the bottles 
and filling is completed while the rotary table makes one rotation, and 
the filled bottles are withdrawn from the rotary table. If feeding of 
bottles to the rotary table and withdrawal of filling-completed bottles 
therefrom is continuously performed, a continuous filling operation 
becomes possible and the operation efficiency can be remarkably increased. 
In most of the conventional filling machines, however, the rotation speed 
of the table is set at an appropriate level and the continuous filling 
operation is conducted at a constant speed without controlling or 
adjusting the operation speed during the filling operation which is 
continuously conducted. If the dimensions of the bottles and/or the 
physical properties of the liquid substance to be filled therein do not 
change, but rather remain uniform, and if the predetermined rotation speed 
corresponds substantially to the maximum capacity of the filling machine, 
no particular disadvantage is caused. However, because the viscosity or 
other physical characteristics of the liquid may change in response to 
changes of the ambient temperature or the like, it is necessary to provide 
a certain margin of safety when the rotation speed of the rotary table is 
set. In other words, it is difficult always to perform the operation at a 
rotation speed corresponding to the maximum filling capacity of the 
filling machine. For example, if the rotation speed of the rotary table is 
set too high, there will be a risk that the quantity of the liquid filled 
in the bottles will become too small when the ambient temperature becomes 
lower. 
According to the present invention, it is possible always to perform the 
filling operation at the maximum filling capacity of the filling machine 
consistent with always completely filling the bottles with the required 
amount of liquid. An embodiment of the present invention will now be 
described by reference to the accompanying drawings.

Referring to the drawings, FIG. 1 illustrates the positions of the parts 
just after feeding a bottle 2 onto the rotary table 1 of the filling 
machine 3. Although the filling machine 3 is fixed to the table 1, the 
fixing frame and the liquid supply pipe is omitted in the drawing. As the 
table 1 rotates, a filling nozzle 4 of the filling machine 3 is inserted 
into the bottle 2 (see FIG. 2), and a predetermined amount of a liquid is 
filled into the bottle 2. Lowering of the filling nozzle 4 is 
accomplished, for example, by lowering a piston 6 by means of an air 
cylinder 5 or the like and thereby pushing down the top end 7 of the 
filling nozzle 4 against a spring 8. A position indicating device 9 is 
mounted on the piston 6. Accordingly, during the filling operation, the 
position indicating device 9 is lowered by a vertical distance h. 
FIG. 3 shows the path of travel of the position indicating devices 9 as 
they move with the rotary table. Arrow 10 indicates the bottle feeding 
position and arrow 11 indicates the position at which the completely 
filled bottle is withdrawn. Arrow 12 indicates the direction of the 
movement of the position indicating devices 9. The amount of filling of 
the bottles is detected just before the bottles are withdrawn from the 
table by detecting the positions of the position indicating devices 9 by 
means of two position detecting devices A and B. The position detecting 
devices A and B are circumferentially spaced apart so that imaginary 
radial lines extending from the axis of rotation of the table through said 
position detecting devices define an included angle .theta. of from 
10.degree. to 30.degree.. Thus, whether or not filling of the bottles is 
completed is detected at the two positions of the devices A and B. Since 
the position indicating devices 9 are lowered by a height h as shown in 
FIG. 2, incomplete filling can easily be detected by a photoelectric tube 
or the like. 
The numbers of completely filled bottles detected at the positions A and B 
are counted with respect to each rotation of the rotary table and the 
proportions of completely filled bottles obtained at the positions A and B 
are determined, that is, the number of bottles that are completely filled 
by the time they reach positions A and B, respectively, are compared to 
the total number of bottles filled by the machine. The ratio, expressed as 
a percentage, of the number of completely filled bottles at positions A 
and B, respectively, to the total number of bottles is the proportion (%) 
at positions A and B. Based on the thus-determined proportions of 
completely filled bottles, the rotation speed of the rotary table is 
controlled in a manner as indicated in the following Table. 
Table 
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Proportion (%) of Completely Filled 
Bottles Rotation Speed 
Position A Position B of Rotary Table 
______________________________________ 
100 100 increased 
95 or more 100 increased 
below 95 100 not changed 
any proportion 
below 100 decreased 
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When the rotation speed of the rotary table is controlled in the foregoing 
manner, the operation can be conducted at the maximum filling capacity of 
the filling machine under ambient conditions. Even if the viscosity and/or 
specific gravity of the liquid to be filled in the bottles is changed, by 
increasing or decreasing the rotation speed of the rotary table in 
response to such changes, the filling rate can be automatically 
controlled. 
In this invention, a conventional filling nozzle assembly may be also used, 
which has an air-blowing nozzle for continuously blowing air and a 
liquid-introducing nozzle. At the beginning of the liquid-filling step, 
the nozzle assembly is set at the operative position wherein it is 
inserted into a bottle and filling of the liquid is started. While the 
liquid is introduced through the liquid-introducing nozzle, air is also 
continuously blown through in the other nozzle. At the time when the 
surface of the liquid filled in the bottle comes very close to, or 
otherwise in contact with, the end of the air-blowing nozzle, the pressure 
of the air increases accordingly, which is immediately detected by a 
detector. This sends a signal to stop filling of the liquid, whereby the 
filling nozzle is moved up to the non-filling position. 
Such reciprocating motion of the filling nozzle may be conducted through a 
piston by means of an air cylinder. A piston in the air cylinder is 
provided with a vertically reciprocable position-indicating device, which 
is observed with a piston position-detecting device. The filling nozzle, 
the piston and the indicating device move up and down together. For 
example, the position-indicating device is a mirror and the 
position-detecting device is a photocell. In this example, the photocell 
detects the reflected radiation from the mirror.