Method for controlling a vacuum packaging machine and vacuum packaging machine

Abstract

In a method for controlling the evacuation process in a chamber to be evacuated in a vacuum packaging machine, the switching time starting with initiation of the evacuation process until reaching a specified threshold value or switching pressure (ps) is determined, then the evacuation time required for reaching a desired ultimate pressure is extrapolated from this switching time and the evacuation process is terminated upon reaching this evacuation time.

Description

BACKGROUND OF THE INVENTION [0001] The invention relates to a method for controlling a vacuum packaging machine and to a vacuum packaging machine. [0002] The following methods have been in use thus far for controlling the evacuation process in vacuum packaging machines: [0003] The simplest method used is time control, i.e. the evacuation process is positively ended after a specified time, which can be pre-selected at the machine, for example. The end result obtained by this method is very imprecise. The inaccuracy of this purely time-controlled process results from a number of parameters that affect the progression of the evacuation process, in particular also from the fact that the chamber volume changes depending on the quantity of goods inserted for packaging, and due to insertion or removal of compensating plates, etc. In order to attain a specific vacuum with this method, it is necessary to set the evacuation time somewhat higher, however with the disadvantage of a significant ...

AI Technical Summary

Benefits of technology

[0007] In the invention, the evacuation process and/or the gas injection are controlled based on the signal of one single sensor, which depending on the type of sensor, switches from one state to a second state, as soon as the pressure in the evacuated or gas-injected chamber has reached a specified threshold value or switching pressure. The switching pressure during the evacuation is considerably higher than the desired ultimate pressure. For example, the switching pressure is on the order of 200 mbar, while the desired ultimate pressure is 20 mbar or 2 mbar.

[0008] Based on the ...

Problems solved by technology

The end result obtained by this method is very imprecise.

The inaccuracy of this purely time-controlled process results from a number of parameters that affect the progression of the evacuation process, in particular also from the fact that the chamber volume changes depending on the quantity of goods inserted for packaging, and due to insertion or removal of compensating plates, etc.

In order to attain a specific vacuum with this method, it is necessary to set the evacuation time somewhat higher, however with the disadvantage of a significant reduction in the efficiency of a vacuum packaging machine (number of packaged units per time unit).

The essential disadvantage of this method consists in the fact that the very low pressure at the end of the evacuation process (ultimate pressure) can be measured only very inaccurately with such instruments.

Suitable sensors and the corresponding analysis electronics are expensive and especially also susceptible to breakdowns.

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