IES990792A2 - A pasteuriser - Google Patents

Abstract

A pasteuriser (1) for pasteurising domestic quantities of milk comprises an outer cylindrical container (2) and an inner cylindrical container (11) located within the outer container (2). An intermediate wall (5) divides the outer container (2) into the main hollow interior region (7) within which the inner container (11) is located, and a secondary hollow interior region (8) in which a control electronics circuit (20) is located. A cavity (12) between the outer and inner containers (2,11) accommodates water for heating milk in the inner container (11) to a pasteurising temperature of 75 degrees Celsius. A water inlet (15) for connecting to a domestic cold water supply admits water into the cavity (12) and an outlet (16) from the cavity (12) forms a weir for retaining water in the cavity (12) to a desired level. A heating element (18) in the cavity (12) heats the water for heating the milk to the pasteurising temperature. A temperature sensor (42) monitors the water temperature for determining the milk temperature. The control circuit (20) times a predetermined time period of twenty seconds after the milk has been raised to a pasteurising temperature, and activates a buzzer (44) at the end of the predetermined time period for alerting a user. The user then flushes cooling water from the domestic cold water supply through the cavity (12) for reducing the temperature of the milk to 20 degrees Celsius. <Figure 2>

Description

“A pasteuriser” The present invention relates to a pasteuriser, and in particular, though not limited to a pasteuriser for pasteurising relatively small quantities of milk, for example, domestic quantities of milk.

According to the invention there is provided a pasteuriser comprising an inner container for receiving a liquid to be pasteurised, an outer container defining a main hollow interior region and having an open mouth for accommodating the inner container into the main hollow interior region of the outer container, the inner container when in the main hollow interior region defining with the outer container a cavity for receiving a temperature controllable medium, a heating means for heating the temperature controllable medium for raising the temperature of the liquid in the inner container to a predetermined pasteurising temperature, an alerting means for alerting to the liquid having been at the predetermined pasteurising temperature for a predetermined time period, and an inlet and an outlet being provided to the cavity for facilitating replacement of the temperature controllable medium with a cooling medium after the temperature of the liquid in the inner container has been at the predetermined pasteurising temperature for the predetermined time period for reducing the temperature of the liquid in the inner container to a predetermined lower temperature.

In one embodiment of the invention the pasteuriser is for pasteurising milk, and the predetermined pasteurising temperature is approximately 75°C. Preferably, the predetermined time period is approximately twenty seconds at which the liquid in the inner container is maintained at the predetermined pasteurising temperature.

In another embodiment of the invention the predetermined lower temperature to which the liquid in the inner container is reduced is approximately 20°C.

Preferably, the inner container is of capacity suitable for pasteurising a quantity of liquid up to 1L, and advantageously, up to 2.5L, and ideally, up to 4.5L.

In one embodiment of the invention the cavity defined between the inner and outer containers is an annular cavity extending around the inner container. Preferably, the cavity extends beneath the inner container.

In a further embodiment of the invention the heating means is located in the cavity, and preferably, beneath the inner container, and preferably, the heating means comprises an electrically powered heating element.

In a further embodiment of the invention a retaining means is provided for retaining the inner container in the main hollow interior region of the outer container with a portion of the inner container being proud of the outer container.

In a further embodiment of the invention the inlet to the cavity is adapted for connecting to a water supply for providing the temperature controllable medium, and the cooling medium.

In another embodiment of the invention a means is provided for determining the level of the temperature controllable medium in the cavity, and advantageously, the means for determining the level of the temperature controllable medium comprises a weir for retaining the temperature controllable medium in the cavity, and advantageously, the outlet defines the weir.

In a further embodiment of the invention a monitoring means is provided for monitoring when the temperature of the liquid in the inner container is at the predetermined pasteurising temperature, and a control means responsive to the monitoring means activates the alerting means after the predetermined time period. Preferably, the control means is responsive to the monitoring means for activating the alerting means when the temperature of the liquid in the inner container is at the predetermined lower temperature.

In one embodiment of the invention an input means is provided for manually inputting a signal to the control means for deactivating the alerting means.

In a further embodiment of the invention the alerting means is an audible alerting means, and preferably, an alarm bell or a buzzer.

In a further embodiment of the invention the monitoring means comprises a temperature sensor, and ideally, the temperature sensor senses the temperature of the temperature controllable medium, and the cooling medium.

In one embodiment of the invention the inner and outer containers are of cylindrical construction.

In another embodiment of the invention a lid is provided for closing an open mouth in the inner container, and preferably, a cooling coil mounted in the lid extends into the inner container for carrying a cooling medium for facilitating reducing the temperature of the liquid in the inner container to the lower predetermined temperature.

Preferably, the control means comprises an electronic control circuit, and ideally, the outer container defines a secondary hollow interior region beneath the main hollow interior region for accommodating the electronic control circuit.

Advantageously, a panel is provided on the outer container for accommodating the input means, and preferably, the input means is provided by a button operated switch.

The invention will be more clearly understood from the following description of some preferred embodiments thereof which are given by way of example only with reference to the accompanying drawings in which; Fig. 1 is a perspective view of a pasteuriser according to the invention, Fig. 2 is a transverse cross-sectional elevational view of the pasteuriser of Fig. 1, Fig. 3 is a circuit diagram of a control circuit of the pasteuriser of Fig. 1, Fig. 4 is a view similar to Fig. 2 of a pasteuriser according to another embodiment of the invention, Fig. 5 is a circuit diagram of a control circuit of the pasteuriser of Fig. 4, and Fig. 6 is a perspective view of a portion of the pasteuriser of Fig. 4.

Referring to the drawings, and initially, to Figs. 1 to 3 there is illustrated a pasteuriser according to the invention indicated generally by the reference numeral 1 for pasteurising a liquid, in this embodiment of the invention milk. The pasteuriser 1 comprises an outer cylindrical container 2 having a base 3 and an upstanding cylindrical side wall 4. An intermediate wall 5 located in the outer container 2 spaced apart from the base 3 divides the outer container 2 into a main hollow interior region 7 and a secondary hollow interior region 8. An open mouth 10 is provided to the main hollow interior region 7. An inner cylindrical container 11 for containing the milk to be pasteurised extends through the open mouth 10 into the main hollow interior region 7, and defines with the side wall 4 and the intermediate wall 5 of the outer container 2 a cavity 12 for receiving a temperature controllable medium, in this embodiment of the invention water for heating and cooling the milk in the inner container 11. A pair of handles 13 on the inner container 11 act as retaining means for retaining the inner container 11 with a top portion thereof proud of the outer container 2, and for retaining the inner container 11 spaced apart above the intermediate wail 5 so that the cavity 12 extends beneath and around the inner container 11. An inlet, namely, a water inlet 15 is provided to the cavity 12 and is adapted for connecting to a water supply for delivering water into the cavity 12. A water outlet 16 from the cavity 12 acts as a weir for determining the level of water in the cavity 12, and for delivering water from the cavity 12.

A heating means, namely, an electric heating element 18 is located in the main hollow interior region beneath the inner container 11 for heating the water in the cavity 12. A control means, namely, control circuit 20 is located in the secondary hollow interior region 8 for controlling the operation of the heating element 18 as will be described below.

A lid 23 is provided for closing an open mouth 24 of the inner container 11. A pair of handles 25 on the outer container 2 facilitate carrying the pasteuriser 1. A control panel 26 is provided on the side wail 4 of the outer container 2.

Referring now in particular to Fig. 3 the control circuit 20 comprises a microcontroller 35, and a power supply 36 powers the micro-controller 35. A mains electricity power supply is supplied to the control circuit through a mains cable 37. A mains switch 38 in the control panel 26 switches the mains supply to the control circuit 20. An isolating switch 39 which is controllable by the micro-controller 35 and a push button switch 40 on the control panel 26 controls mains electricity to the heating element 18.

A monitoring means, in this embodiment of the invention a temperature sensor 42 located on the intermediate wall 5 monitors the temperature of the water in the cavity 12 so that the micro-controller 35 can determine when the milk is at the pasteurising temperature. A timer subroutine in the micro-controller 35 times a twenty second time delay period after the micro-controller 35 determines that the milk has reached the pasteurising temperature. After the timer subroutine in the micro-controller 35 has timed out, the micro-controller 35 operates the isolating switch 39 for isolating the heating element 18 from the mains electricity supply 37, and an alerting means provided by a buzzer 44 is activated by the micro-controller 35. The buzzer 44 is sounded to alert a user that the milk has been held at the pasteurising temperature for twenty seconds, and the temperature of the milk should be reduced rapidly. A push button switch 45 on the panel 26 is provided for facilitating manual switching off of the buzzer 44. The temperature of the milk is rapidly brought to a lower temperature, in this embodiment of the invention 20°C by flushing cold water through the cavity 12 through the water inlet 15 and the water outlet 16. On the microcontroller 35 in response to the temperature sensor 42 determining that the temperature sensed by the temperature sensor 42 corresponds to the milk being at approximately 20°C the micro-controller 35 again activates the buzzer 44 for indicating to the user that the pasteurising process has been completed. The user can again switch off the buzzer 44 by the button switch 45 and place the milk in a refrigerator.

A light.emitting diode 46 is also provided in the control panel 26 for giving a visual alert each time the buzzer 44 has been activated.

In use, the milk to be pasteurised is placed in the inner container 11 which is then located in the outer container 2. The water inlet 15 is connected to a mains cold water supply, and the cavity 12 is filled with water until the water commences to flow though the water outlet 16. The water to the cavity 12 is turned off and the mains electricity switch 38 is switched on. The micro-controller 35 operates the isolating switch 39 for powering the heating element 18. On the micro-controller 35 determining that the temperature sensed by the temperature sensor 42 indicates that * . the milk is at the pasteurising temperature of 75°C the timer routine in the microcontroller 35 is activated for timing the twenty second delay. On the twenty second delay being timed out the micro-controller 35 operates the isolating switch 39 for isolating the heating element 18 from the mains electricity supply 37, switches on the light emitting diode 46 and operates the buzzer 44 for alerting the user to the fact that the milk has reached the pasteurising temperature and has been held at the pasteurising temperature for twenty seconds. The user switches off the buzzer 44 using the button switch 45 and turns on the cold water supply to the cavity 12. The cold water is continuously flushed through the cavity 12, and on the micro-controller 35 determining that the temperature sensed by the temperature sensor 45 corresponds to the milk being at approximately 20°C the micro-controller 35 again activates the buzzer 44 and switches on the light emitting diode 46 to indicate to the user that the milk has been pasteurised, and should now be placed in a refrigerator. The user may then switch off the buzzer 44 using the button switch 45, and should also switch off the mains switch 38.

Referring now to Figs. 4 and 6 there is illustrated a pasteuriser 50 which is substantially similar to the pasteuriser 1, and similar components are identified by the same reference numeral. The pasteuriser 50 comprises a cooling coil 51 mounted in the lid which extends into the inner container 11 for further accelerating cooling of the milk from the pasteurising temperature to the lower temperature of 20°C. An inlet 52 and an outlet 53 are provided to and from the cooling coil 51 for connecting the cooling coil 51 to a mains water supply for providing a continuous flow of cooling water through the cooling coil 51 during cooling of the milk. A solenoid controlled valve 55 controls the supply of water to the water inlet 15, and the solenoid controlled valve 55 is responsive to the micro-controller having determined that the temperature of the milk has been held at the pasteurising temperature for twenty seconds for commencing flushing of cold water through the cavity 12 for cooling the milk to the lower temperature of 20°C. A solenoid valve 56 is also provided on the water inlet 52 to the coil 51 for similarly controlling the flow of water through the coil 51 for cooling the milk. Additionally, a water level detector 57 is provided in the cavity 12 for detecting when the level of water in the cavity 12 has initially reached a sufficient level for heating the milk to the pasteurising temperature.

Operation of the pasteuriser 50 is substantially automatic, and once the milk has been placed in the inner container 11 and the inner container 11 has been placed in the outer container 2, and the two water inlets 15 and 52 are connected to a mains cold water supply, the mains switch 38 may be switched on to operate the pasteuriser 50. Initially, the micro-controller 35 controls the solenoid valve 55 on the water inlet 15 for admitting water Into the cavity 12 until the water level detected by the water level detector 57 has reached just below the level of the water outlet 16, at which stage the solenoid valve 55 is switched off. The micro-controller 35 operates the isolating switch 39 for powering the heating element 18 and the micro-controller 35 monitors the temperature sensor 42. On the micro-controller 35 determining that the temperature of the milk is at the pasteurising temperature of 75eC the timer routine in the micro-controller 35 times the twenty second time delay, and the microcontroller 35 switches off the heating element, and opens the solenoid valve 55 and the solenoid valve 56 for flushing cooling water through the cavity 12 and the cooling coil 51. When the micro-controller 35 determines that the temperature sensed by the temperature sensor 42 corresponds to the milk being at the lower temperature of 20°C the solenoid valve 55 and the solenoid valve 56 are switched off and the buzzer 44 is activated and the light emitting diode 46 is switched on by the microcontroller 35 for indicating that the milk has been pasteurised.

A user can then place the milk in a refrigerator.

In this embodiment of the invention the buzzer is not sounded to indicate when the milk has been held at the pasteurising temperature for the predetermined time period of twenty seconds, since this is not required due to the fact that the micro-controller 35 controls the solenoid valve 55 and the solenoid valve 56 for commencing cooling of the milk automatically.

In this particular embodiment of the invention the pasteuriser is suitable for pasteurising a quantity of milk not exceeding 2.5L. It is however envisaged that the pasteuriser may be provided for pasteurising milk quantities up to 4.5L. However, it is the intention of the invention to essentially provide a domestic pasteuriser which may be used in farm households for pasteurising milk which has been milked from cows on the farm, and particularly, for pasteurising domestic quantities of milk suitable for the farm household only. With a heating element of 2.2 watts and a cold water flow rate of 10L per minute and a water temperature in the range of 12’C to 18'C, it has been found that the pasteurisers according to the invention can pasteurise 2.5L of milk in approximately 5 minutes to 10 minutes, depending in the initial milk temperature and the cold water temperature.

The invention is not limited to the embodiments hereinbefore described which may be varied in construction and detail.