US 5,205,129 A · Apparatus for freezing and dispensing semi-frozen food products having dual freezing chambers and method

Abstract

An apparatus for freezing and dispensing semi-frozen food products having two freezing chambers, one compressor for supplying refrigerant to both freezing chambers, one beater drive motor for driving the beaters in both chambers, two solenoid valves control flow of refrigerant from the single compressor to the evaporators for the freezing chambers and periodic pulse width modulated signals are applied to operate the two solenoid valves alternately during each period and signals are modulated to have substantially equal duty cycles in an initial freeze mode and to have unequal duty cycles when product is dispensed from only one freeze chamber.

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Claims25

Dependent claims

In a soft-serve dispensing apparatus including two freezing chambers each having an evaporator and a rotary beater, dispensing valve means for dispensing semi-frozen product from the freezing chambers, dispense sensing means for sensing when product is dispensed from each freezing chamber, product condition sensing means for sensing a condition of the product in the freezing chambers that is related to a minimum servable product viscosity;

product supply means for supplying unfrozen product to the freezing chambers, refrigeration producer means including a compressor having a compressor drive motor, a condenser, a high pressure refrigerant supply means including a refrigerant expansion control means individual to each evaporator means and low pressure refrigerant return line means for returning refrigerant from both evaporator means to the compressor, and beater drive means for driving the beaters, the improvement comprising, the beater drive means has a single drive motor and power transmission means for connecting the drive motor to the beaters in both freezing chambers to drive both beaters concurrently, said refrigerant expansion control means each comprising an on-off solenoid valve, means for starting an auto-cycle operation of the apparatus, and control means for controlling operation of the compressor drive motor and the beater drive motor and the solenoid valves,
(a) said control means including means responsive to starting an auto-cycle of the apparatus for operating the apparatus in an initial freeze mode, said control means including means operative in the initial freeze mode for generating and applying peroidic pulse width modulated signals having substantially equal duty cycles PWF1 to the solenoid valves associated with the evaporators for both freezing chambers where the duty cycle PWF1 provides an effective refrigerant flow rate sufficient to increase the viscosity of the product in the freezing chambers,
(b) said control means including means responsive to the dispense sensing means for operating apparatus in a first refreeze mode, the control means including means operative in the first refreeze mode when product is dispensed from one of the freezing chambers for generating and for applying a periodic pulse width modulated signal to the solenoid valve associated with said one of the freezing chambers having a duty cycle PWF2 and for generating and applying a periodic pulse width modulated signal to the solenoid valve associated with the other of the freezing chambers having a duty cycle PWH, where the duty cycle PWF2 provides an effective refrigerant flow rate sufficient to increase the viscosity of the product in said one freezing chamber and the duty cycle PWH provides an effective refrigerant flow rate sufficient to substantially maintain the viscosity of the product in said other freezing chamber,
(c) said control means further including means responsive to said product condition sensing means for operating the apparatus in a second refreeze mode, said control means including means operative in said second refreeze mode when the product in one freezing chamber is below a minimum servable product viscosity for generating and applying a periodic pulse width modulated signals having a duty cycle PWF2' to the solenoid valve associated with said one of the freezing chambers and for generating and applying a periodic pulse width modulated signals having a duty cycle PWH' to the solenoid valve associated with the other of the freezing chambers where the duty cycle PWF2' provides an effective refrigerant flow rate sufficient to increase the viscosity of the product in said one freezing chamber and the duty cycle PWH' provides an effective refrigerant flow rate to substantially maintain the viscosity of the product in said other freezing chamber.

1 more element

In a soft-serve dispensing apparatus including two freezing chambers each having an evaporator and a rotary beater, dispensing valve means for dispensing semi-frozen product from the freezing chambers, dispense sensing means for sensing when product is dispensed from each freezing chamber, product supply means for supplying unfrozen product to the freezing chambers, refrigeration producer means including a compressor having a drive motor, a condenser, a high pressure refrigerant supply means including a refrigerant expansion control means individual to each evaporator means and low pressure refrigerant return line means for returning refrigerant from both evaporator means in the compressor, and beater drive means for driving the beaters, the improvement comprising, the beater drive means has a single drive motor and power transmission means for connecting the drive motor to the beaters in both freezing chambers to drive both beaters concurrently, beater drive load sensing means responsive to the combined drive load for driving the beaters in both freezing chambers, product temperature sensing means individual to each chamber for sensing a product temperature condition correlative with a minimum servable product viscosity, said refrigerant expansion control means each comprising an on-off solenoid valve, means for setting a combined beater load threshold correlative with the desired viscosity for servable product in the freezing chambers, means for starting operation of the apparatus, and control means for controlling operation of the compressor drive motor and the beater drive motor and the solenoid valves,

(a) said control means including means responsive to starting of the apparatus for operating the apparatus in an initial freeze mode, said control means including means operative in the initial freeze mode for energizing the compressor drive motor and beater drive motor and for generating and applying pulse width modulated signals having substantially equal duty cycles PWF1 to the solenoid valves associated with the evaporators for both freezing chambers and for continuing operation in the initial freeze mode until the combined drive load exceeds the load threshold, where the duty cycle PWF1 provides an effective refrigerant flow rate sufficient to increase the viscosity of the product in the freezing chambers,
(b) said control means including means responsive to a dispense signal from the dispense sensing means associated with one of the freezing chambers for operating apparatus in a first refreeze mode, the apparatus including means operative in the first refreeze mode for energizing the compressor drive motor and the beater drive motor and for generating and for applying a periodic pulse width modulated signal to the solenoid valve associated with said one of the freezing chambers having a duty cycle PWF2 and for generating and applying a periodic pulse width modulated signal to the solenoid valve associated with the other of the freezing chambers having a duty cycle PWH and for continuing operation in the first refreeze mode until the combined beater load exceeds said load threshold, where the duty cycle PWF2 provides an effective refrigerant flow rate sufficient to increase the viscosity of the product in said one freezing chamber and the duty cycle PWH provides an effective refrigerant flow rate sufficient to substantially maintain the viscosity of the product in said other freezing chamber,
(c) said control means further including means responsive to said temperature sensing means for operating the apparatus in a second refreeze mode, said control means including means operative in said second refreeze mode when the product in one freezing chamber is below a minimum servable product viscosity for energizing said compressor drive motor and said beater drive motor and for generating and applying periodic pulse width modulated signals having a duty cycle PWF2' to the solenoid valve associated with said one of the freezing chambers and for generating and applying periodic pulse width modulated signals having a duty cycle PWH' to the solenoid valve associated with the other of the freezing chambers, until the product in said one of the freezing chambers reaches the minimum servable product viscosity, where the duty cycle PWF2' provides an effective refrigerant flow rate to increase the viscosity of the product in said one freezing chamber and the duty cycle PWH' provides an effective refrigerant flow rate to substantially maintain the viscosity of the product in said other freezing chamber.

A method of controlling operation of a soft-serve dispensing apparatus including two freezing chambers each having an evaporator and a rotary beater, dispensing valve means for dispensing semi-frozen product from the freezing chambers, product supply means for supplying unfrozen product to the freezing chambers, a single beater drive motor for driving the beater means in both freezing chambers, refrigerant producer means including compressor means having a compressor drive motor and condenser means, and an on-off solenoid valve for controlling refrigerant flow to the eva means associated with each freezing chamber, said method including the steps of:

(a) sensing start-up of the apparatus and operating the apparatus in an initial freeze mode comprising generating and applying pulse width modulated signals having substantially equal duty cycles PWF1 to the solenoid valves associated with the evaporators for both freezing chambers, where the duty cycle PWF1 provides an effective refrigerant flow rate sufficient to increase the viscosity of the product in each freezing chamber;
(b) sensing when product is dispensed from only one of the freezing chambers and operating the apparatus in a first refreeze mode, generating and applying a periodic pulse width modulated signal to the solenoid valve associated with said one of the freezing chambers having a duty cycle PWF2 and generating and applying a periodic pulse width modulated signal to the solenoid valve associated with the other of the freezing chambers having a duty cycle PWH, where the duty cycle PWF2 provides an effective refrigerant flow rate sufficient to increase the viscosity of the product in said one freezing chamber and the duty cycle PWH provides an effective refrigerant flow rate sufficient to substantially maintain the viscosity of the product in said other freezing chamber;
(c) sensing a condition of the product in each freezing chamber that is correlative with a minimum servable product viscosity and, when the viscosity of the product in one freezing chamber is below a minimum servable product viscosity, operating the apparatus in a second refreeze mode comprising generating and applying periodic pulse width modulated signals having the duty cycle PWF2 to the solenoid valve associated with the freezing chamber that is below the preselected minimum servable product viscosity and generating and applying periodic pulse width modulated signals having the duty cycle PWH to the solenoid valve associated with the other freezing chamber.

A method of controlling operation of a soft-serve dispensing apparatus including two freezing chambers each having an evaporator and a rotary beater, dispensing valve means for dispensing semi-frozen product from the freezing chambers, product supply means for supplying unfrozen product to the freezing chambers, a single beater drive motor for driving the beater means in both freezing chambers, means for sensing the combined drive load for driving the beaters in both freezing chambers, and refrigerant producer means including compressor means having a compressor drive motor and condenser means, and an on-off solenoid valve for controlling refrigerant flow to the evaporator means associated with each freezing chamber, said method including the steps of:

(a) setting a combined load threshold correlative with the desired viscosity of a servable product in the freezing chambers;
(b) sensing start-up of the apparatus and operating the apparatus in an initial freeze mode comprising energizing the compressor drive motor and the beater drive motor and generating and applying pulse width modulated signals having substantially equal duty cycles PWF1 to the solenoid valves associated with the evaporators for both freezing chambers, where the duty cycle PWF1 provides an effective refrigerant flow rate sufficient to increase the viscosity of the product in each freezing chamber, and continuing in the initial freeze mode until the combined drive load exceeds the preset load threshold;
(c) setting a reference product temperature for minimum servable product viscosity in the freezing chambers;
(d) sensing when product is dispensed from only one of the freezing chambers and operating the apparatus in a first refreeze mode comprising energizing the compressor drive motor and the beater drive motor and generating and applying a periodic pulse width modulated signal to the solenoid valve associated with said one of the freezing chambers having a duty cycle PWF2 and generating and applying a periodic pulse width modulated signal to the solenoid valve associated with the other of the freezing chambers having a duty cycle PWH, where the duty cycle PWF2 provides an effective refrigerant flow rate sufficient to increase the viscosity of the product in said one freezing chamber and the duty cycle PWH provides an effective refrigerant flow rate sufficient to substantially maintain the viscosity of the product in said other freezing chamber, and continuing in the first refreeze mode until the combined drive load exceeds the load threshold;
(e) sensing the temperature of the product in each freezing chamber and comparing the product temperature in each chamber with the reference product temperature, and when the product temperature in one freezing chamber is above the reference product temperature, operating the apparatus in a second refreeze mode comprising energizing said compressor drive motor and said beater drive motor and generating and applying periodic pulse width modulated signals having the duty cycle PWF2 to the solenoid valve associated with the freezing chamber that is above the reference product temperature and generating and applying periodic pulse width modulated signals having the duty cycle PWH to the solenoid valve associated with the other freezing chamber, and continuing operation in the second refreeze mode until the product temperature in said one of the freezing chambers is lowered to the reference product temperature.

2 more elements

Dependencies are inferred from the claim text.

Description6,654 words

Summary1,435 words

#The present invention relates to an apparatus for freezing and dispensing semi-frozen food products. As product is dispensed from one end of a freezing chamber, unfrozen product ingredients are introduced at the other end of the freezing chamber and the time and amount of refrigeration required to freeze the incoming product ingredients to a servable product viscosity is dependant in large part on the rate at which product is dispensed from the freezing chamber. In apparatus having dual freezing chambers, product can be intermittently dispensed from either freezing chamber and the duration of each dispensing operation and the intervals between dispensing operations from the two chambers varies widely. Thus, in a given period of time, one freezing chamber may be subject to a number of dispensing operations and require a high rate of refrigeration while the other is subject to relatively few dispensing operations or even none at all and accordingly would require a relatively lower rate of refrigeration.

#Apparatus have heretofore been made having two freezing chambers for freezing and dispensing semi-frozen food products using a single compressor to supply refrigerant to the evaporators for the two freezing chambers. However because of changes in rates at which product is dispensed, the two freezing chambers frequently require refrigeration at different rates and times. Controlling the rate of flow of refrigerant from a single compressor to accommodate the different refrigeration requirements in the two freezing chambers has presented some problems. In an attempt to overcome these problems, the assignee of the present invention has heretofore used separate refrigerant expansion control valves for each freezing chamber and also provided a solenoid on/off valve at the inlet of each evaporator and a solenoid on/off valve at the outlet of each evaporator to enable selective isolation of one or the other evaporators from the refrigeration system. This substantially increased the overall cost of the apparatus and the complexity of the controls required to operate the apparatus. Further, this prior refrigerant control system did not enable independant control of the rate of flow of refrigerant to the two evaporators when both freezing chambers required refrigeration at the same time.

#In apparatus for freezing and dispensing frozen food products having two freezing chambers, it has been common practice to use separate drive motors for driving the beaters in the two chambers to enable driving of the beater in only one or the other or both freezing chambers, as desired. Such apparatus also used individual load sensors for sensing the torque or drive load on the motors for each chamber, to control supply of refrigerant to the associated freezing chamber. The use of separate beater drive motors and transmissions for connecting each drive motor to the beater in the associated freezing chamber, not only increased the cost of the apparatus but also increased the space required inside the cabinet such that it was difficult to make an apparatus having a size sufficiently small for a countertop unit.

Brief description of the drawings6 figures

#FIG. 1 is a diagram of an apparatus for freezing and dispensing semi-frozen food products and a control system therefor according to a first embodiment of this invention;

#FIG. 2 is a flow chart of a program for operating the control system of FIG. 1;

#FIGS. 3a, 3b and 3c are graphs illustrating the pulse width modulated signals applied to the solenoid valves associated with both freezing chambers, under different operating modes;

Detailed description5,094 words

#FIG. 1 illustrates an apparatus for freezing and dispensing semi-frozen food products having two freezing chambers C1 and C2 for dispensing food products of different flavors or types. The freezing chambers are commonly in the form of an elongated cylinder and respectively have beaters B1 and B2 mounted for axial rotation in the cylinders. Product to be frozen is supplied to the cylinders C1 and C2 from product supplies PS1 and PS2, and evaporators E1 and E2 extend around the freezing chambers C1 and C2 for refrigerating the product therein. The product supplies are generally arranged to supply a liquid comestible and an edible gas in proportions to provide a semi-frozen food product having the desired overrun. The liquid comestible may, for example, be of the type used to make soft ice cream, sherbert, shakes or ice slushes, and the gas can be air, nitrogen, carbon dioxide or a mixture thereof. As is conventional, the product supplies may also be refrigerated by suitable apparatus (not shown) to pre-cool the liquid therein to preselected above freezing temperatures.

#Selectively operable dispensing valve means are provided for controlling dispensing of semi-frozen product from the freezing chambers, preferably at the end of the cylinders remote from the product supply inlet. As diagrammatically illustrated in FIG. 1, valves V1 and V2 are provided in heads 11 at a discharge end of the cylinder for respectively dispensing semi-frozen product from chambers C1 and C2. It is also common practice in dual chamber apparatus to provide a third dispensing valve (not shown) which is arranged to dispense product from both freezing chambers simultaneously, when a mixture of the products from the two freezing chambers is desired.

#Means are provided for producing a signal when product is dispensed from either freezing chamber. This means may comprise switches S1 and S2 arranged to sense when a dispensing valve is open to dispense product from freezing chambers C1 and C2 respectively. The dispense sensing means can also be arranged to sense other conditions that change when product is dispensed from a freezing chamber, such as the infeed of product from the associated product supply as occurs when the dispensing valve is opened, or the change in vicosity of the product in the freezing chamber as occurs when the dispensing valve is opened. As diagrammatically shown, the switches are positioned so as to be actuated when the associated dispensing valve is opened or raised to dispense a product. Some apparatus have a third valve for dispensing product simultaneously from both freezing chambers, and in such apparatus the third dispensing valve is arranged in a manner well known in the art to operate both switches S1 and S2 simultaneously when the third valve is opened to dispense product from both freezing chambers.

Apparatus for freezing and dispensing semi-frozen food products having dual freezing chambers and method

Life of this patent

Apparatus for freezing and dispensing semi-frozen food products having dual freezing chambers and method

Life of this patent

Life of this patent

Abstract

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Claims25

Description6,654 words

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Classification14 codes

Life of this patent

Description6,654 words