GB2278934A

GB2278934A - Actuator control module

Info

Publication number: GB2278934A
Application number: GB9311909A
Authority: GB
Inventors: Anthony Alford
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-06-09
Filing date: 1993-06-09
Publication date: 1994-12-14
Anticipated expiration: 2013-06-09
Also published as: GB9311909D0; GB2278934B

Abstract

A control module for an actuator (e.g. for a valve in a central heating system) comprises its own power source 1, local input means 6 and means 5 for remotely communicating with a central control system preferably without wires. The power source may be a battery or a thermoelectric generator using the Seebeck effect. The module may be incorporated into the body of the actuator. <IMAGE>

Description

Electrical Control Actuator This invention relates to an electrically powered actuator control which can be fitted within the actuator body and derive its electric power requirements from the medium being controlled.

Alternatively it can be powered from a remote power source.

The actuator may be a solenoid or motorised valve or it may be any form of electrically powered mechanism such as a solenoid that operates a heating or air conditioning vent/flap or it can be a relay.

Background Valves used in hot water heating systems.

Fluid control valves are commonly used in central heating systems to divert the flow of hot water between the Hot Water tank and the Central heating system. These valves tend to operate by means of a geared motor powered from the electrical mains supply to open and close a port orifice.

Another type of valve found in such systems is the Thermostatic Radiator valve which is connected in series with the hot water radiator and regulates the flow through the radiator by way of a plunger which closes the port orifice progressively as the ambient temperature increases. The principle of operation exploits the fact that a fluid expand/contracts with the application of heat/cold and can be designed to extend/retract a plunger out of a metal reservoir to achieve the desired valve operation and temperature regulation.

The need for an Intelligent Energy Switch.

To achieve optimum operating control of heating systems there is a requirement for an intelligent energy switch to pass/stop/divert and control the flow of an energy source such as hot air or hot water at each local heating outlet (hot air vent or hot water radiator). This switch must have full access to all relevant upto date data relating to the system variables (time, boiler temperature, temperature settings, air temperature, and any other relevant data) and be able to act upon this data to control the energy usage at that local point within the system. Any heating system or other control process using such switches to control the flow of a valuable media such as fluid or gas can be optimised to give optimum performance.

Hot Water Heating Systems In the quest to reduce energy consumption wasted in wet heating systems it is necessary to switch off radiators that are in areas that are not in use. To do this successfully the intelligent energy switch must have access to current information relating to room requirements and respond to other data relating to occupancy, current energy (flexible tariff rates) and any other relevant data relating to improving the performance and economy level with which the radiator heats the area in question. Thermostatic valves fail in this respect since they can only adjust radiator heat output about a set temperature manually set at the radiator in question.

The present invention relates to an Electrical Actuator Control which meets the requirements of an intelligent energy switch ( hereafter referred to in its abbreviated form EAC ) which contains a mechanical actuator mechanism which is powered by electrical means which in turn is controlled by an electronic control circuit which has the capability to both transmit and receive data to and from remote locations via a communicating network and further has the capability of processing data. All of these function can be located and performed within the actuator body.

A unique feature of heating systems incorporating the use of the EAC is that with knowledge of the system in which it operates, it is possible to adjust and balance the system and request changes in operation from the boiler, other EAC's and of other devices in the system to maintain the whole heating system performance optimised at all times.

The use of the EAC is particularly but not exclusively for the control of energy in hot water heating systems.

The EAC meets the requirements for an effective intelligent energy switch and has the following features.

1.0 Open/Close or Divert a port orifice to pass or stop fluid/gas flow 2.0 Pass any intermediate fluid/gas flow 3.0 communicate via data network to EAC's and other equipment.

3.1 Receive data from remote EAC devices connected to the data network 3.2 Transmit data to remote EAC devices as described in 3.0.

4.0 Respond to information transmitted from remote sources such as a room thermostat, another EAC, programmable controller or other sources 5.0 The EAC is electrically powered 5.1 Electrical power can be supplied from a separate power source 5.2 Electrical power can be supplied by the heat energy from the fluid/gas source converted via a solid state Seebeck Thermoelectric Generator mounted within the EAC.

5.3 Electrical power can be supplied via a light cell fitted to the outside of the Intelligent Valve.

5.4 Electrical power can be supplied by a battery cell fitted within the EAC.

5.5 Electrical power can be supplied by means of electrical magnetic induction.

The EAC can be powered from any combination of the above energy sources.

The data network described earlier can be implemented using any of the following techniques or a combination of any of them to suit the application.

Signal Cable: Twisted pair, coaxial cable or other cable type.

Air borne: Radio Frequency, Infra Red.

Power Line: Mains injection Fibre Optic Cable Actuators This invention will operate any electrically powered mechanism.

Examples include solenoids or step motors and any additional mechanism which is attached to the solenoid such as a lever or flap or valve.

Another example of actuators is a relay where the mechanism is a set of electrical contacts and can control the flow of electrical current.

The unique features of this invention is best described by way of an example.

Consider a hotel of say 50 rooms with a yearly occupancy level of say 40%. Clearly the 60% of rooms not in use is typically shared amongst all the rooms on different days through out the year.

The current practice is that the radiators in all of the rooms are on when ever the main boiler is set to operate. This results in a 60% waste of heat to the hotel operator.

The same hotel with EAC's fitted to each radiator can ensure that radiators are only on when the room is booked by communicating the booking data from the reception desk via a Personal Computer connected to the data network of the EAC's.

Similarly further economy can be achieved by connecting occupancy sensors to the EAC network to which the EAC's can respond by reducing the hot water flow to the radiator to achieve a minimum temperature when the room is booked but not currently occupied. An example of the EAC's interactive capability is typified by a radiator that is at the end of a long piping run and even when the valve is fully open the requested room temperature cannot be achieved due to the loss of heat in the piping run The EAC can respond to send data to the boiler and its associated controls to increase the water temperature until the local room requirements are met. At the same time all other EAC's will adapt to the new change in input temperature.

By similar means the EAC in conjunction with other EAC's can balance a complicated heating system by adaptive control.

The solution to the above system problems and other processes can be solved by the use of the EAC due to the features described earlier.

A detailed description of a particular implementation of a hot water heating system using the Electrical Actuator Control follows with reference to Fig.l through to Fig. 10.

Fig.9 shows a typical system implementation.

This implementation of the EAC is for a self powered EAC requiring no physical electrical connections to the outside world.

Illustrated are a number of radiators fitted with EAC's (EAC-1 to EAC-nn). These communicate with other EAC's, Room Stats (R/Stats), Occupancy Sensors (Occ.Sense), Boiler and a typical data input device.

Fig.l shows a block diagram of the functions of the Electrical Actuator Control. The thermoelectric element is exposed to a temperature gradient ( typically 10 to 20 degrees Centigrade ) between the incoming hot water flow to the radiator and the lower temperature return flow. Alternatively the lower temperature could be achieved using a heatsink to ambient air temperature. This could provide typical temperature gradient of 10 to 50 degrees Centigrade. Electrical power ( typically 50 to 300milliWatts for a nominal device with a heat pumping capacity of 13Watts ) is generated by the thermoelectric element 1.The low impedance source voltage generated ( typically 50 to 500 milli volts ) is converted by a voltage converter circuit 2, to a usable voltage level V+ (typically 9-12volts). The voltage V+ charges a storage device such as a capacitor or a rechargeable battery 3, which meets the short term high energy load requirements such as actuators indicators and transceiver functions. All logic processing, storage of data and resident programmes are performed by the Central Processing Unit (CPU) 4.

The CPU has the primary function of updating its data base of system variables such as boiler/outside/room temperatures and settings, time, occupancy and tariff rates (received from data network) ; and local variables such as room and water temperatures, time of day, voltage levels, state of charge, room temperature settings and process this data with a resident programme to determine what action to perform. The actions that can be performed by the CPU are :- to operate the actuator to open/close; to send data onto the data network via the Transceiver 5; to request data from other devices attached to the data network.

The input/output interface 6, performs buffering between load and input connections and the CPU.

The primary function of the I/O is to provide the correct electrical drive circuit to operate the Electrical Actuator 7.

The Actuator in this example is a four phase stepper motor and its four winding stepping sequence is controlled from the CPU 4, and buffered by four transistor amplifiers in the I/O interface 6. The motor shaft is fitted via a gearbox with an offset cam with a throw of 3mm which will depress a valve plunger against a spring to close the orifice through which the hot water flows into the radiator.

The cam is designed with an end stop so that the motor will stall when this is reached ; the resulting stall current is detected by a stall current comparator in the I/O interface 6. This motor-stall data is passed to the CPU 4, via the I/O lines.

Thermoelectric Generator Fig.2 details how a temperature gradient is produced across the Thermoelectric element (TE) 102.

The principle of operation is based upon the 'Seebeck' effect which is well documented. The thermoelectric generator consists of several N and P pellets connected electrically in series and thermally in parallel sandwiched between two ceramic plates one side of which is connected to hot temperature source and the other connected to a cold temperature source . If an electrical load is connected across the stack of series P-N junctions a current will flow and power transferred to the electrical load.

The temperature gradient is provided by thermal contact with the hot flow pipe 101, on the one side of the TE plate and the other TE plate in thermal contact with either the cooler return radiator pipe 105, or alternatively to a heatsink to ambient air. This can be accomplished by incorporating the TE plate inside the actuator body, which could be a moulded or a cast part providing opportunity for the flow and return fluid flow to have intimate thermal contact with either side of the TE plates.

For the this application a Marlow Industries MI1064T thermoelectric cooler of 13watts rating is specified and used in reverse mode which with a heat differential of 10 to 50 degrees centigrade will generate electrical power at an efficiency of 0.5 to 2.3% relating to usable power of 50 to 300milliWatts. The higher power rating would be achieved with ambient air at 20deg.C and with a heat sink of thermal resistance to ambient air of ldeg.C per watt.

Clearly with systems with continuous hot and cold water supplies available the power out put from the TE element can be increased and heats ink requirements minimised.

Voltage Converter Fig.3 The function of this circuit is to raise the voltage of around 0.3 volts from the TE element to a higher usable voltage of typically 12volts. This is achieved by the transistor Q1 (National Semiconductor part Jell0, N channel FET) switching winding W1 at a frequency determined by the feedback components W2 and C2. W2 is magnetically coupled to Wl and a voltage transformation takes place by the ratio of 'voltage in' * W2/W1 . The output voltage will equal this value less the diode volt drop due to D1 and other small losses in the circuit. The other components shown are for the purposes of impedance matching C1, biasing R1, and smoothing C3.

Energy Storage Fig.5 For the application of low temperature heating systems the instantaneous power available from a practical sized TE element is small (50 to 300milliWatts). Proven spring loaded radiator valve plungers require a force of circa 3Kgf (30N) to depress a plunger 3mm to close off the water flow against the pump pressure in the system.

It is the purpose therefore of the Energy storage device to satisfy the short term demand of such loads and accept a constant charge from the voltage converter to service this demand. For this application a pp3 NiCad battery is specified of 8.4volt nominal voltage and llOmAhr capacity. The charge rate available from the voltage converter of .OSWatts/9volts= 5.5 mAmps relates well to the manufacturers recommended trickle charge rate of 0.05 to 0.1 * nominal capacity (0.055mAmp).

The operation of the actuator is only going to occur infrequently and for a short duration. A suitable stepper motor of Swatts running power with a shaft torque of 20mN is specified. The Appendix A details the calculations showing that at a minimum radiator temperature of 40deg.C the Energy Storage device can service 130 Actuator operations per hour and increasing linearly to 780 operations per hour at a radiator temperature of 80deg.C The Central Processing Unit (CPU) Fig.5 The function of this device can be clearly stated by the detailed specification of how a system is expected to perform. There are many low cost processing devices available on the market and a typical device would be the Motorola part MC143120.This device contains sufficient memory and processing power for the purpose and also takes care of all protocol and communicating functions via the transceiver module. The process of implementing the system spec. with such a device is well documented and will not be laboured here. It is sufficient to say this function can be performed using prior art devices and procedures.

An important function for the CPU to perform in this application of the EAC is to monitor battery usage and charge availability and ensure that in the event of insufficient charge from the heating source the actuator is operated to the open position to ensure recharging will occur when the base energy source is returned.

Transceiver Fig.6 This is a radio frequency tranceiver. This module in other installations can take the form of a twisted pair cable network or any of the alternatives discussed earlier.

In all cases data from the network will be sent out and received under the instruction of the CPU.

Its key function is to enable the EAC to be aware of the latest changes in any system variables that are included in the System Specification. Also it enables the EAC to send its latest data to other EAC devices and to any other relevant control device connected to the data network.

A suitable module is the RF-10 Model 50070 supplied by the Echelon Corporation.

Input/Output Interface Fig.7 The- function of this circuit is to ensure all voltage levels between the CPU and input /output devices are correctly matched. Its main feature is the power amplification from the CPU output to the actuator load. In the case of the four phase step motor the stepping sequence output on four of the 11 available I/O lines from the MC143120 CPU is buffered via four transistor amplifiers (Al to A4). Other functions performed are shown in Fig.7.

These functions include Stall current detection (A6,R5); Temperature sensing of radiator input water for local processing and transmission to main boiler control; Thermoelectric voltage for battery management processing; LED output and switch for test purposes.

Actuator Fig.8 As described earlier the actuator can take many different forms and in this application is implemented with a stepper motor and gearbox with an offset cam which can be set in any position from fully closed to fully open with a resolution of 1%. See Appendix B for calculations.

Fig.9 and Fig.10 show a system implementation and the communication topology of a typical system described in the foregoing text.

Appendix A Calculations for Actuator Load Requirements Manufacturer: Airpax part 9904-112-31004 Gear box:- 25:2 ratio Motor load of 4phase step motor SWatts Step Angle 7.5degrees Steps per revolution: 48 Max Pull-in rate 240steps/sec Minimum charge available from thermoelectric generator at 40degrees centigrade is 0.05Watts.

Energy stored in lhour period is 0.05*60*60*0.9=162 Watt-seconds. (Efficiency at 90%) Time available per hour for actuator operation = Watt-seconds/motor power = 162Wattsec/5Watt = 32 seconds.

Time to rotate gear box output shaft half a revolution to move cam through a 3mm swing to fully depress valve plunger: Time(halfrev) = 48/2 * 25/2 * 1/240 = 1.24 seconds Actuator operations possible per hour at minimum charge rate = 162Wattsec/l.25sec = 130.

This capability increases to 780 operations per hour at temperatures as high as 80deg.C Appendix B Calculation for Actuator Torque requirements The gear box increases motor shaft torque by ratio of 25:2. It also increases step resolution from 48steps per rev to 48*25/2 = 600 steps per rev at cam.

To rotate the cam half a revolution to depress the valve plunger the 3mm against the spring pressure of 3Kg.f(30Newtons) equates to 300 steps.

Torque required: Force * Radius = 30*0.003 =0.09Nm Torque available from Motor shaft = 0.02Nm Torque available from gearbox cam = 0.02*25/2*0.8 = 0.2 Nm. (Efficiency of gear box at 80%)

Claims

Claims 1 An Electrical Actuator Control (EAC) comprises an electrical control module which provides the means to operate and control an actuator mechanism. The actuator mechanism has the means to interupt the flow of a gas or fluid. The actuator mechanism is powered by electrical means from the control module. The control module comprises further functional modules which provide the means to perform the functions of electrical power conversion and storage together with the function of communicating with remotely located communicating devices via a communicating network together with the function of processing and storing of data together with providing an interface to locally connected devices.
2 An Electrical Actuator Control as claimed in claim 1 provides means to incorporate the control module within the body of the actuator
3 An Electrical Actuator Control as claimed in claim 1 whereby the EAC is incorporated into the actuator body so that the actuator and EAC becomes a single entity.
4 An Electrical Actuator Control as claimed in claim 1 and any preceeding claim provides control means to Open/Close or Divert a port orifice of an actuator to pass or stop fluid/gas flow as per its programmed instructions.
5 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the control means to enable an actuator to pass any intermediate fluid/gas flow.
6 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the means via a transceiver module to communicate on a data network to EAC's and other equipment and devices.
7 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the means via the transceiver module to receive data from remote EAC devices and other devices connected to the data network.
8 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the means to Transmit data to remote EAC devices and other equipment.
9 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the means to process and respond to information and data transmitted from remote devices such as a room thermostat, another EAC, programmable controller or other sources
10 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the means to operate from electrical power supplied from a separate power source.
11 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the means to convert and store electrical power supplied by the heat energy derived from the fluid/gas source being controlled by the EAC and converted via a solid state Seebeck Thermoelectric Generator mounted within the EAC.
12 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the means to derive its power from any available energy source.
13 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the means to convert and store electrical energy supplied by a light cell fitted to the outside of the actuator.
14 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the means to convert and operate from electrical energy supplied by a battery cell fitted within the EAC.
15 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the means to convert and store electrical energy supplied by means of electrical magnetic induction. The EAC can be powered from any combination of the above energy sources.
16 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the means to communicate over the data network described earlier and can be implemented using any of the following techniques or a combination of any of them to suit the application. Signal Cable: Twisted pair, coaxial cable or other cable type. Air borne: Radio Frequency, Infra Red. Power Line: Mains injection, Fibre Optic Cable
17 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the means to operate and control any electrical powered mechanism.
18 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the means to respond and process information and data held on computers systems that are connected via the network.
19 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the means to send data to a computer on the network and update its files.
20 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the means to interact with other devices or equipment or other EAC's on the network and will send instructions relating to its state. The other EAC's will interpret the instructions and amend their operations so as to provide a balanced control system.
21 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the means to operate without connection to external wires, through the use of a Radio Frequency communications network and is power generated by thermo electric power conversion and/or a battery cell.
22 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the solid state thermoelectric means to generate it own power through low temperature sources in the range of typically 40 to 100 degrees centigrade.
23 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the means to generate its own power through high temperature sources.
24 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the means to recharge its battery cell over its operating cycle.
25 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the means to store operational programmes which will provide instructions to the EAC on how to operate and respond to changes of state.
26 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the logic processing means to control the inputs to the system as well as the outputs to the actuator and the network to which the EAC is attached.
27 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the means when using thermo electric generation to increase its performance by extending the temperature ranges through the use of a heat sink to the ambient air.
28 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the means to convert the low impedance voltage from the thermo generation process to a usable voltage 910volts via a voltage converter circuit and impedance matching network.
29 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the logic processing means to control its own resident database holding its local data and programmes governing its specific implementation/application area. eg; hotels or domestic applications.
30 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the means to update itself of water/room temperature, time of day and other local conditions relevant to its operation or other networked EAC's and connected devices.
31 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the means to form part of a closed control system or can form part of a complex open control.
32 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the means, when working together in a heating system to provide the boiler with information to ensure a efficient heating cycle.
33 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the means to EAC's when working together in a heating system will ensure each room is has the maximum heat available to meet its heating target over the shortest time period.
34 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the means to ensure when self powered that the maximum heat requested supports the self powering needs as well as their room heating requirements.
35 An Electrical Actuator Control as claimed in claim 1 and any preceding claim provides the means to perform self diagnostics and report any fault information eg; low battery, circuit fault, actuator fault etc.
36 An Electrical Actuator Control substantially as hereinbefore described with reference to Figure 1 of the accompanying drawings.
37 An Electrical Actuator Control substantially as hereinbefore described with reference to Figure 2 of the accompanying drawings.
38 An Electrical Actuator Control substantially as hereinbefore described with reference to Figure 3 of the accompanying drawings.
39 An Electrical Actuator Control substantially as hereinbefore described with reference to Figure 4 of the accompanying drawings.
40 An Electrical Actuator Control substantially as hereinbefore described with reference to Figure 5 of the accompanying drawings.
41 An Electrical Actuator Control substantially as hereinbefore described with reference to Figure 6 of the accompanying drawings.
42 An Electrical Actuator Control substantially as hereinbefore described with reference to Figure 7 of the accompanying drawings.
43 An Electrical Actuator Control substantially as hereinbefore described with reference to Figure 8 of the accompanying drawings.
44 An Electrical Actuator Control substantially as hereinbefore described with reference to Figure 9 of the accompanying drawings.
45 An Electrical Actuator Control substantially as hereinbefore described with reference to Figure 10 of the accompanying drawings.