IE50659B1 - Automatically operating liquid measuring and temperature control systems - Google Patents

Abstract

Figure 1 illustrates a liquid-measuring and temperature-regulating process whereby water can be fed to a vessel (11). The system (1) has a chamber (2) with an inlet orifice (2a) and an outlet orifice (2b). The feed lines (3, 4, 5) serve for feeding liquid of differing temperature to the inlet orifice (2a), the valve device (6, 7, 8) controlling the flow of liquid through each of the feed lines. A device (5) responds to changes in temperature of the liquid and is actuated so as to adjust the valve device. A device (12) measures the quantity of liquid which has flowed through the chamber and serves for adjusting the valve device, the vessel (11) finally being supplied with a body of liquid of desired quantity and size.

Description

This invention relates to automatically operating liquid measuring and temperature control systems.

The invention is particularly, but not exclusively, concerned with measuring and controlling the temperature of water supplied to bread dough mixers.

Bread dough mixers require a measured supply of water at a temperature controlled to fine limits.

One known system requires an operative to be aware of the temperatures of water available from water sources at different temperatures and to carry out calculations before mixing water from the sources. However, this system demands accurate measurement of the water temperatures, whereas the easily-read temperature indicators used are prone to failure or are inaccurate.

Other known systems require an operative to run off water before a stable temperature at the required level is obtained. These systems are obviously wasteful of water and energy. - 2 50659 In addition, in the referred systems, if the temperatures of the water sources vary, then any calculations are rendered invalid and recomputing becomes necessary. Temperature-controlled blending valves are currently available but are somewhat insensitive and cannot be relied upon to maintain a supply of water at a required temperature if the pressure of the water varies.

Attempts have been made to provide systems with corrective feedbacks but these function on the basis of open loop corrections for errors in previous operations. Hence the initial blend must be regarded as a trial run.

According to one aspect of the present invention, an automatically operating liquid measuring and temperature control system for delivering liquid to a receiver, comprises duct means for supplying liquid at different temperatures to the receiver, valve means for controlling the flow of liquid supplied to the receiver, means sensitive to changes in the temperature of liquid supplied to the receiver, and operable to adjust said valve means and means for measuring liquid supplied to the receiver and also operable to adjust said valve means whereby the receiver is ultimately provided with a body of liquid of desired quantity and temperature.

According to another aspect of the present invention, an automatically operating liquid measuring and temperature control system for delivering liquid to a receiver, comprises a chamber having an inlet and an outlet, feed ducts for supplying liquid at different temperatures to the inlet of the chamber, valve means for controlling the flow of liquid through each of the feed ducts, means sensitive to changes in the temperature of liquid in the chamber and operable to adjust said valve means, and means for measuring liquid delivered by the chamber and also operable to adjust said valve means whereby the receiver is ultimately provided with a body of liquid of desired quantity and temperature. - 3 S0g58 In each case, the valve means are preferably adjusted by a single control device operable by the temperature-sensitive means and the measuring means. Furthermore, the single control device, the temperature-sensitive means and the measuring means preferably comprise electronic means.

The invention also comprises the combination of the system, (according to either aspect thereof), and bread dough mixer means.

The various aspects of the invention will now be described by way of example only, with reference to the accompanying drawings, wherein:Figure 1 illustrates, in a semi-diagrammatic manner, a liquid measuring and temperature control system according to the invention, Figure 2 is a flow chart of the control algorithm, Figures 3 and 4 are water heat/weight graphs of the system when in operation, Figure 5 is a flow chart illustrating how the system may be used in a breadmaking plant, and Figure 6 illustrates a modification of the system illustrated by Figure 1.

With reference to Figure 1, an automatically operating liquid measuring and temperature control system 1 for delivering water to a receiver (11), which is subsequently supplied to a bread dough mixer, is illustrated therein.

The system 1 comprises a chamber in the form of a blending duct 2 having an inlet 2a and an outlet 2b, feed ducts 3, 4 and 5 for supplying pressurised water at different temperatures to the inlet 2a of the blending duct 2, and valve means comprising solenoid valves 6, 7 and 8 for controlling the flow of water through each of the feed ducts. The system 1 further comprises means in the form of a transducer 9 sensitive to changes in the temperature of water in the blending duct 2, and operable, through a controller 10, to - 4 50659 adjust the valves 6, 7 and 8, and means comprising a weight-sensitive transducer 12 for measuring the water delivered by the chamber/blending duct 2, and also operable to adjust, through the controller 10, the valves 6, 7 and 8 whereby the receiver is ultimately provided with a body of water of desired quantity and temperature.

The controller 10, and transducers 9 and 12 are electronic components. The controller 10 comprises a conventional form of microprocessor based single board computer comprising MPU, RAM, ROM and EAR0M memories, 1/0 devices etc., containing a programme devised to suit the system 1. The temperaturesensitive transducer 9 is a high accuracy (Grade 1) platinum resistance thermometer. The weight-sensitive transducer 12 is a strain gauge based load cell.

The receiver 11 comprises a weighing vessel.

The transducers 9 and 12 are connected to the controller 10 by input signal lines 20 and 21 and, when in operation, generate continuous, i.e. non-pulse voltage outputs. The solenoid valves 6, 7 and 8 are connected to the controller 10 by output signal lines 22, 23, 24. The controller can be programmed using external controls, not shown.

Water in the feed duct 3 is at normal or room temperature, (say 15°C); that in the duct 4 is relatively warm, say 55°C, and that in the duct 5 relatively cool, say 5°C, which is chilled. The temperatures are not critical and need not be known to an operative. However, the required temperature of water in the receiver 11 must lie between the warmer and cooler temperatures.

In operation, assuming a batch of dough is to be mixed, the required weight and temperature of the water required for the mix are first noted and the - 5 β 89 controller 10 automatically set up accordingly, taking into account any previous error, as well as the required temperature and weight of water.

With additional reference now to the flow chart provided by Figure 2, the operation commences (100). The normal water control valve 6 is first opened (101) by the controller 10. Water is allowed to flow through the feed duct 3 for one period, say one second (102) and then the heat flow is calculated by the controller 10 as the product of the weight addition in the time period and the temperature during that time period (103). This heat flow value is added to the summation of total heat. If the total weight of water discharging into the vessel 11 does not exceed the required weight (104) and does not exceed a certain fixed proportion of the required weight, say one eighth (106), then a further time period is allowed to elapse, and the calculations carried out again electronically.

When the weight of water in the vessel 11 equals this proportion of the required weight (106) the temperature of the arriving water is stored (107).

If the flag HCIN, which indicates that warm or cool waters are already in, is not set (108), the valve 6 controlling the flow of “normal water is turned off (109).

If the required temperature is now greater (110) than the stored temperature (107), warm water is selected, (111), using solenoid valve 7. On the other hand, if the required temperature is less than the stored temperature, cool water is selected, (116), using solenoid valve 8.

The weights and temperatures of the water continue to be periodically (112, 117) measured and total heats calculated (113, 118) until a calculated reference point is reached (114, 119). - 6 βθβΒ8 The basis for the calculation of this point, considering the heated path, is that the heat to go, (required heat minus total heat), becomes less than the heat which could be put in with normal water. ((Required WT - Weight) x normal temperature).

The basis for the calculation of this point, considering the cool water path, is that the heat to go becomes greater than the heat which could be put in with normal water.

At this point, (115, 120), the warm or cool water control valves 7 and 8 are closed. The programme of the controller 10 is such that, when the flag HCIN is set, (121), indicating that the warm or cool waters are now in, the controller 10 causes the “normal water control valve 6 to be opened once again (101). The flow chart will again follow the path of operations 102, 103, 104, 106, 107, 108. On reaching this point, as HCIN is now set, the system returns to operation 102. This loop will continue until the weight of water in the vessel 11 reaches the required weight (104). At this point the normal water control valve 6 is closed. The vessel li will now contain the required weight of water at the required temperature.

Reference to Figures 3 and 4 show the summation of total heat with the increasee of weight of water, as well as the three phases of the blend (Normal, Warm, Normal; or Normal, Cool, Normal).

It should be noted that the system by virtue of its continuous summation of heat, and storage of water at normal temperature after a suitable delay, allows for any standing temperature variations in the supplies to be compensated for, eliminating the need to run off excessive amounts of water, which is also wasteful of energy.

Summing up therefore, the water is fed into the weighing vessel/receiver 11 by the blending duct 2, a continuous measurement of its temperature is taken by the - 7 50659 temperature transducer 9 and a voltage proportional to this temperature transmitted to the controller 10 along signal line 20.

Initially normal water is selected on a fixed periodic basis and the weight of water in the weighing vessel 11 and temperature of the water discharged thereto monitored. The heat present in each time period is calculated and a continuous summation kept of weight and heat of water in the vessel 11.

When the weight of water in the vessel 11 equals a small proportion, say one eighth, of the required total weight, the normal supply is shut off using solenoid valve 6, and either warm or cool water is selected depending on whether the required temperature is above or below the normal temperature.

The second water supply is kept energised until the total summated heat reaches a reference point calculated by the system. At this point the supply of “normal water is reinstated.

When the total weight reaches the required weight then the solenoid valves 6, 7 and 8 are de-energised.

The system has the facility to modify the required temperature and to compensate for temperature errors in previous weighments. As previously stated, the temperature of water in the feed ducts 3, 4 and 5 need not be known to an operative.

The system provides for the continuous measurement of water temperature and weight and for blending of the water supplies on the basis of heat integration.

The system may make use of analogue circuitry or of digital circuitry.

Three sources of feed water are preferred but two, (relatively warm and relatively cool), can be used if three cannot be provided. - 8 βΟβΒβ A pump may be disposed in the blending duct 2 if required and may be started and stopped by the controller 10.

Figures 3 and 4 are heat/weight graphs of the system.

In Figure 3, the heat is the product of weight and temperature of the water (calories). The slope of the graph represents the temperature of the water.

During the normal11 phase it can be seen that the accrued heat falls below the imaginary line joining 00 and the required heat/weight point. (This line obviously represents the required temperature).

Consequently heated water is next selected. This may fluctuate in temperature, hence the slope in this phase varies. It is however generally steeper than the desired temperature line and so it eventually crosses the line extrapolated back from the target at the normal water slope. At this point the heated water is switched off and normal turned on again.

This then continues to the required weight line.

Figure 4 represents the train of events taking place in the normal : chilled : normal mode.

Figure 5 is a flow chart showing how the system 1 can be used in combination with a bread dough mixer 200, bread dough processing apparatus 201 and baking oven 202 to produce bread loaves 203.

Mixer 200 is preferably of the form disclosed by British Patent Application No. 2,015,362A and which is used in a system disclosed by British Application No. 14997/77. (Published as South African Patent No. 78/2119).

Figure 6 illustrates a modified system 1a wherein a chamber/blending duct (2) is not provided. Instead, feed ducts 3, 4 and 5 deliver water direct to receiver/weighing vessel 11. In this modified system, the single temperature- 9 50658 sensitive transducer 9 has been replaced by three similar transducers 9^, 9b, 9c with input lines 20a, 20b, 20c respectively.

The weight transducer 12 may be replaced by other measuring means. For example, a water flow meter may be disposed in the chamber/blending duct 2 to monitor the volume of water passing therethrough and to signal controller 10 accordingly.

As used herein, the term adjust obviously includes fully opening or closing the valve means, (valves 6, 7 and 8), as well as operating them so that they take up intermediate positions between fully opened or closed.

Claims (19)

1. An automatically operating liquid measuring and temperature control system for delivering liquid to a receiver, comprising duct means for supplying liquid at different temperatures to the receiver, valve means for controlling tbe flow of liquid supplied to the receiver, means sensitive to changes in the temperature of liquid supplied to the receiver, and operable to adjust said valve means, and means for measuring liquid supplied to the receiver and also operable to adjust said valve means whereby the receiver is ultimately provided with a body of liquid of desired quantity and temperature.

2. A system as claimed in Claim 1, wherein the valve means are adjusted by a single control means.

3. A system as claimed in Claim 1 or 2, wherein the means sensitive to changes in temperature comprises electronic means.

4. A system as claimed in Claim 1, 2 or 3, wherein the means for measuring liquid supplied to the receiver comprises electronic means.

5. A system as claimed in Claim 2 or Claims 3 or 4 when dependent on Claim 2, wherein the control means comprise electronic means. - 10 50658

6. A system as claimed in Claim 5, wherein the control means can be programmed.

7. A system as claimed in Claim 3, wherein the means sensitive to changes in temperature comprise electronic transducer means, which, in operation, generate a non-pulse voltage output.

8. A system as claimed in Claim 4, wherein the means for measuring liquid supplied to the receiver comprises electronic transducer means which, in operation, generate a non-pulse voltage output.

9. An automatically operating liquid measuring and temperature control system for delivering liquid to a receiver, comprising a chamber having an inlet and an outlet, feed ducts for supplying liquid at different temperatures to the inlet of the chamber, valve means for controlling the flow of liquid through each of the feed ducts, means sensitive to changes in the temperature of liquid in the chamber and operable to adjust said valve means, and means for measuring liquid delivered by the chamber and also operable to adjust said valve means whereby the receiver is ultimately provided with a body of liquid of desired quantity and temperature.

10. A system as claimed in any one of Claims 1 to 9, in combination with bread dough mixer means.

11. A system as claimed in any one of Claims 1 to 9, in combination with bread dough mixer means, and bread dough processing apparatus.

12. A system as claimed in any one of Claims 1 to 9, in combination with bread dough mixer means, bread dough processing apparatus, and a baking oven.

13. A method of automatically operating liquid measuring and temperature control comprising blending liquids of different temperatures to provide a body - 11 SGSS© of liquid of desired quantity and temperature, substantially as hereinbefore described with reference to Figures 1 to 5 of the accompanying drawings.

14. A method of automatically operating liquid measuring and temperature control comprising blending liquids of different temperatures to provide 5 a body of liquid of desired quantity and temperature, substantially as hereinbefore described with reference to Figures 1 to 5 of the accompanying drawings, modified substantially as hereinbefore described with reference to Figure 6 of said drawings.

15. A system as claimed in Claim 1, substantially as hereinbefore described 10 with reference to Figures 1 to 5 of the accompanying drawings.

16. A system as claimed in Claim 1, substantially as hereinbefore described with reference to Figures 1 to 5 of the accompanying drawings, modified substantially as hereinbefore described with reference to Figure 6 of said drawi ngs. 15

17. The combination claimed in Claim 10, 11 or 12, substantially as hereinbefore described with reference to Figures 1 to 5 of the accompanying drawings.

18. The combination claimed in Claim 10, 11 or 12, substantially as hereinbefore described with reference to Figures 1 to 5 of the accompanying

19. 20 drawings, modified substantially as hereinbefore described with reference to Figure 6 of said drawings.