Method and apparatus for the control of the flow rate of the refrigerating fluid in ice cream making machines

Abstract

Method for the control of the flow rate of refrigerating fluid in ice cream making machines comprising a vapour-compression refrigerating circuit provided as a minimum with a compressor, a condenser, an evaporator and a main valve for injecting refrigerating fluid into the said evaporator, the method comprising the following steps: measuring the temperature-pressure values of the fluid at the outlet of the evaporator; tapping off, on the basis of the measurement taken in the first step, a flow of hot gas at the outlet of the compressor; and sending this tapped-off flow of gas to a point downstream of the main refrigerating fluid injection valve. This method is carried out by means of an apparatus comprising at least one tapping-off line that takes a flow of gas from the outlet of this compressor and sends it to a zone of this circuit situated between the main valve and the evaporator, means are provided on this line to control and monitor this tapped-off flow of gas.

We claim:  
     
         1 . Method for the control of the flow rate of refrigerating fluid in ice cream making machines comprising a vapour-compression refrigerating circuit provided at least with a compressor, a condenser, an evaporator and a main valve for injecting refrigerating fluid into the said evaporator, the method being characterized by the following steps: 
 measuring the temperature-pressure values of the fluid at the outlet of the said evaporator;    tapping off, on the basis of the measurement taken in the above mentioned first step, a flow of hot gas at the outlet of the said compressor; and    sending the said tapped-off flow of gas to a point downstream of the main refrigerating fluid injection valve.    
     
     
         2 . Method according to  claim 1 , comprising the additional step of controlling the increase in volume of the ice cream produced by appropriately varying the evaporation of the refrigerating fluid with respect to the said tapped-off flow of hot gases.  
     
     
         3 . Apparatus for carrying out the method according to  claim 1 , for the control of the flow rate of refrigerating fluid in ice cream making machines comprising a vapour-compression refrigerating circuit provided at least with a compressor, a condenser, an evaporator and a main valve for injecting refrigerating fluid into the said evaporator, comprising at least one tapping-off line that takes a flow of gas from the outlet of the said compressor and sends it to a zone of the said circuit situated between the said main valve and the said evaporator, means being provided on the said line to control and monitor the said tapped-off flow of gas.  
     
     
         4 . Apparatus according to  claim 3 , further comprising a valve on the said tapping-off line to inject the said tapped-off flow at a point downstream of the said main valve of the refrigerating circuit.  
     
     
         5 . Apparatus according to  claim 4 , further comprising downstream of the said evaporator a sensor for monitoring the pressure of the expanded gas leaving the said evaporator.  
     
     
         6 . Apparatus according to  claim 5 , comprising a control device connected to the said pressure sensor and acting on the said injection valve.  
     
     
         7 . Method according to  claim 1  for use in ice cream making machines comprising a freezing cylinder; an evaporator in heat exchange relation with said freezing cylinder; a stirrer for stirring the ice cream mixture inside said freezing cylinder and a motor for driving said stirrer, in which for preventing overloading of the said motor that drives the said stirrer there is further provided a control device connected to said sensor for monitoring the pressure of the expanded gas leaving the said evaporator, the said devices acting together on said solenoid injection valve in such a way as to prevent an excessive decrease in the temperature-pressure values in said evaporator.  
     
     
         8 . Method according to  claim 7 , further comprising a sensor at the outlet of said evaporator for determining the evaporation temperature at the outlet of said evaporator, in order to correct the said temperature by the injection of hot gases.