WO1995006203A1 - Mise sous tension d'elements chauffants electriques - Google Patents

Mise sous tension d'elements chauffants electriques Download PDF

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Publication number
WO1995006203A1
WO1995006203A1 PCT/GB1994/001549 GB9401549W WO9506203A1 WO 1995006203 A1 WO1995006203 A1 WO 1995006203A1 GB 9401549 W GB9401549 W GB 9401549W WO 9506203 A1 WO9506203 A1 WO 9506203A1
Authority
WO
WIPO (PCT)
Prior art keywords
heating element
temperature
driving
power supply
glow plug
Prior art date
Application number
PCT/GB1994/001549
Other languages
English (en)
Inventor
Thomas Tsoi-Hei Ma
Original Assignee
Ford Motor Company Limited
Ford Werke A.G.
Ford France S.A.
Ford Motor Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB9317667A external-priority patent/GB2280759A/en
Application filed by Ford Motor Company Limited, Ford Werke A.G., Ford France S.A., Ford Motor Company filed Critical Ford Motor Company Limited
Publication of WO1995006203A1 publication Critical patent/WO1995006203A1/fr

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
    • F02P19/00—Incandescent ignition, e.g. during starting of internal combustion engines; Combination of incandescent and spark ignition
    • F02P19/02—Incandescent ignition, e.g. during starting of internal combustion engines; Combination of incandescent and spark ignition electric, e.g. layout of circuits of apparatus having glowing plugs
    • F02P19/025—Incandescent ignition, e.g. during starting of internal combustion engines; Combination of incandescent and spark ignition electric, e.g. layout of circuits of apparatus having glowing plugs with means for determining glow plug temperature or glow plug resistance
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D23/00—Control of temperature
    • G05D23/19—Control of temperature characterised by the use of electric means
    • G05D23/20—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature
    • G05D23/24—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature the sensing element having a resistance varying with temperature, e.g. a thermistor
    • G05D23/2401—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature the sensing element having a resistance varying with temperature, e.g. a thermistor using a heating element as a sensing element

Definitions

  • the present invention is concerned with a method for driving electrical heating elements, such as glow plugs, to bring them to their operating temperature as quickly as possible.
  • EGI exhaust gas ignition
  • Glow plugs are usually operated by a simple ON/OFF switch that connects them to the vehicle battery.
  • V the heat output of a glow plug
  • R the resistance of the glow plug.
  • the battery voltage can vary significantly, especially when the vehicle is being started from cold.
  • the resistance value R is selected to be fairly high, to permit the glow plug to remain intact even when the maximum battery voltage applied across it for some time. Because the need for reliability must always take precedence over rapid operation, glow plugs have in the past always needed around twenty to -thirty seconds to reach their operating temperature, which is not entirely satisfactory.
  • heating elements other than glow plugs in the operation of an internal combustion engine.
  • One such application is in fuel vaporisers that heat the fuel to improve combustion quality.
  • the vaporisation of the fuel is especially desirable during cold starts, when the intake manifold is cold, and it is clearly desirable to have the vaporisation effective immediately the engine is cranked so that it can assist with the first firing.
  • the present invention therefore seeks to provide a method of driving a heating element, such as a glow plug, that reduces the time taken by the heating element to reach its operating temperature.
  • a method of driving a heating element such as a glow plug from a power supply which comprises applying an unsustainably high current through the heating element, periodically deriving a measure of electric power consumed by the heating element of the glow plug, periodically estimating the cooling effect on the element by heat losses through at least radiation, predicting the temperature of the element from the difference between the energy gain and energy loss, decreasing or switching off the applied current in response to the predicted element temperature exceeding a first threshold value and increasing or switching on the applied current in response to the predicted element temperature dropping below a second threshold value.
  • a method of driving a heating element such as a glow plug from an electrical power supply which comprises measuring the supply voltage periodically, initially driving an unsustainably high current through the heating element for a length of time related to the value of the measured voltage to bring the heating element rapidly to its operating temperature, disconnecting or reducing the supply voltage to prevent damage to the heating element and subsequently alternately reconnecting and disconnecting the supply voltage periodically to maintain the heating element, temperature between upper and lower threshold limits.
  • a method of driving a heating element such as a glow plug from an electrical power supply which comprises measuring the supply voltage periodically, initially driving an unsustainably high current through the heating element for a length of time related to the value of the measured voltage to bring the heating element rapidly to its operating temperature and subsequently regulating the mean current supply to the heating element to maintain the heating element temperature between upper and lower threshold limits.
  • a further application of the invention is in engines provided with electrically heated catalysts.
  • an electrically heated catalyst In order to minimise the time taken by an electrically heated catalyst to reach its light off temperature, it has been proposed to drive the heating element using an unregulated supply derived directly from the engine alternator with its regulator switched off or by-passed.
  • the danger encountered with such a system is that of burning out the heating element of the catalyst because the unregulated alternator is capable of overdriving the heating element.
  • rapid heat rise is achieved by. over-driving the heating element, in other words passing a current through it that would after some time destroy the heating element.
  • This is achieved most simply by using a heating element rated for a lower supply voltage, for example, using a glow plug with a 1.7V rating in a vehicle with a 12V power supply battery. After the operating temperature is reached, steps are taken to reduce the mean current drawn by the heating element to prevent its damage and keep it at its operating temperature.
  • Figure 1 shows a block diagram of a system embodying the invention
  • FIG. 2 is a flow chart to explain the operation of the heat management unit in Figure 1.
  • the invention is concerned with heating a heating element 12 by controlling the current supplied to it from a power supply 10 through a switching unit 14 the latter being controlled by a heat management unit 16.
  • the power supply need not be stable and may for example be the battery voltage in a motor vehicle which can drop to as low as 9 volts while the starter motor is being used in cranking the engine and can rise to more than 13 volts when the alternator is charging the battery.
  • the heating element 12 may be a glow plug of a diesel engine, or a glow plug used as an igniter in a fuel burner or an exhaust gas ignition system. As a further alternative the heating element may form part of a fuel vaporiser. In all cases it is desired to raise the temperature of the heating element as quickly as possible to its operating temperature regardless of the variations in supply voltage.
  • a heating element having a rated voltage lower than the minimum supply voltage is employed.
  • the current supplied to the heating element would be unsustainable and is sufficiently high to cause permanent damage to the heating element.
  • This excess current can rapidly raise the temperature of the heating element to achieve the desired objective but a heat management unit 16 is now required to prevent overheating and burning out of the heating element.
  • thermocouple used to measure the temperature of the heating element would itself have a thermal capacity and will take time to reach the same temperature as the heating element. But during this time the heating element will have burnt out before the current to it could be reduced.
  • the heat management system of the preferred embodiment therefore operate on the basis of an open loop. Based upon the power supplied to the heating element it is possible to estimate the increase in temperature and based upon the temperature one can estimate- heat losses from the heating element. It is therefore possible to estimate the instantaneous temperature of the heating element at all times, preferably by the use of suitable software and to switch the power supply to the heating element on and off or to modulate it so as to maintain the estimated temperature of the heating element within a permissible band-.
  • FIG 2 there is represented a program loop that can be included in the engine management computer. Certain elements are assumed to be already present in the computer, such as clock signal to set the timing of the program loop and means for providing a signal that is a measure or an estimate of the starting temperature of the heating eleme c. There will usually be present such a signal within an engine management computer. For example if the heating element is part of a fuel vaporiser the engine coolant temperature can serve as a good indication of the heating element temperature. In the case of a catalytic converter, the operating temperature of the catalyst needs to be .sensed or estimated in order to avoid activating the EGI system or the fuel burner during warm starts .
  • the first step taken in the loop, in the block designated 30, is to measure the instantaneous value of the supply voltage. This allows the power drawn from the power supply to be estimated in the block 32 which then increments the estimated temperature EST , but only during cycles in which the power supply is connected to the heating element.
  • the next block 34 estimates the heat losses from the heating element and decrements the value of T accordingly.
  • the heat losses will mostly be through radiation in the case of a glow plug used as an igniter and these follow a well known mathematical relationship, but it is also possible to compensate for losses through convection and conduction, especially in the case of a fuel vaporiser.
  • the estimated temperature is compared with upper and lower threshold values T m ⁇ . and MIN . If the estimated temperature lies within the permitted band, the status of the power supply connection is not changed in that cycle. If the estimated temperature exceeds the maximum permitted temperature j ⁇ , then the power supply connection is set to OFF in the block 38 whereas if it is less than the lower threshold T M M T IN M ,' the status of the power supply connection is set to ON in the block 40. In all three cases, in other words whether the status of the power supply connection is changed or not, the program loops back to the block 30 where the voltage of the power supply is measured at the start of the next clock cycle.
  • the lines of code that implement the flow chart in Figure 2 become effective.
  • the estimated temperature T_ s will be found to be below its minimum threshold T M M T I-N- and the status of the connection to the power supply will be set- to ON.
  • the estimated temperature E will rise and will continue to be incremented in consecutive clock cycles until the maximum threshold ⁇ - ⁇ is reached when the status of the power supply connection will be set to OFF.
  • the power supply will not be reconnected for several cycles until the estimated temperature T EST again drops below its minimum threshold.
  • the heating element will at first be continuously connected to the-power supply for a length of time determined by the voltage of the power supply and in the starting temperature. Thereafter, the power supply will be pulsed with a mark to space ratio matched to the heat losses from the heating element, so as to keep its temperature within the permissible band.
  • the mean steady state heating current may be controlled by pulsing the power supply with an appropriate mark to space ratio, by reducing the supply voltage through a voltage divider or by a connecting a resistance in series with the heating element. It is furthermore possible to modulate the supply voltage instead of switching it totally ON and OFF, and this can assist i improving the expected life of the heating element .

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)

Abstract

L'invention se rapporte à un procédé d'excitation d'un élément chauffant tel qu'une bougie de préchauffage à partir de l'alimentation électrique. Ce procédé consiste à mesurer périodiquement la tension d'alimentation, à appliquer initialement un courant de surexcitation extrêmement fort à l'élément chauffant pendant un temps associé à la valeur de la tension mesurée, afin d'amener rapidement ledit élément chauffant à sa température de fonctionnement et ensuite, à réguler le courant moyen appliqué à l'élément chauffant, afin de maintenir sa température entre une limite seuil supérieure et une limite seuil inférieure.
PCT/GB1994/001549 1993-08-25 1994-07-18 Mise sous tension d'elements chauffants electriques WO1995006203A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9317667.5 1993-08-25
GB9317667A GB2280759A (en) 1993-08-06 1993-08-25 Operation of electrical heating elements

Publications (1)

Publication Number Publication Date
WO1995006203A1 true WO1995006203A1 (fr) 1995-03-02

Family

ID=10741008

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1994/001549 WO1995006203A1 (fr) 1993-08-25 1994-07-18 Mise sous tension d'elements chauffants electriques

Country Status (1)

Country Link
WO (1) WO1995006203A1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1719909A1 (fr) * 2005-05-06 2006-11-08 Magneti Marelli Powertrain S.p.A. Moteur à combustion interne avec bougie à incandescence dans le cylindre et procédé pour la faire fonctionner
DE102006048225A1 (de) * 2006-10-11 2008-04-17 Siemens Ag Verfahren zur Bestimmung einer Glühkerzentemperatur
EP2292921A1 (fr) * 2009-07-14 2011-03-09 BorgWarner BERU Systems GmbH Procédé destiné au fonctionnement d'une bougie de préchauffage
CN103687095A (zh) * 2008-07-17 2014-03-26 百略智慧财产责任有限公司 加热线控制电路及加热元件的操作方法
US20220154647A1 (en) * 2020-11-18 2022-05-19 Pratt & Whitney Canada Corp. Method and system for glow plug operation

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2099920A (en) * 1981-06-10 1982-12-15 Diesel Kiki Co Circuit for controlling glow plug energization

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2099920A (en) * 1981-06-10 1982-12-15 Diesel Kiki Co Circuit for controlling glow plug energization

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1719909A1 (fr) * 2005-05-06 2006-11-08 Magneti Marelli Powertrain S.p.A. Moteur à combustion interne avec bougie à incandescence dans le cylindre et procédé pour la faire fonctionner
US7528346B2 (en) 2005-05-06 2009-05-05 Magneti Marelli Powertrain S.P.A. Internal combustion engine provided with a heating device in a combustion chamber and a control method for the heating device
DE102006048225A1 (de) * 2006-10-11 2008-04-17 Siemens Ag Verfahren zur Bestimmung einer Glühkerzentemperatur
CN103687095A (zh) * 2008-07-17 2014-03-26 百略智慧财产责任有限公司 加热线控制电路及加热元件的操作方法
EP2292921A1 (fr) * 2009-07-14 2011-03-09 BorgWarner BERU Systems GmbH Procédé destiné au fonctionnement d'une bougie de préchauffage
US20220154647A1 (en) * 2020-11-18 2022-05-19 Pratt & Whitney Canada Corp. Method and system for glow plug operation
US11739693B2 (en) * 2020-11-18 2023-08-29 Pratt & Whitney Canada Corp. Method and system for glow plug operation

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