JP2004170063A - Control method of glow ignition mechanism for heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a control method of a glow ignition mechanism for a heater, especially for a vehicle heater, and to reduce a load of the glow ignition mechanism to the optimum. <P>SOLUTION: In this control method of the glow ignition mechanism 14 for the heater 12, especially for a vehicle heater, a target pre-incandescent voltage Us to be applied to the glow ignition mechanism is formed with a basic pre-incandescent duty ratio during the basic pre-incandescent continuous time on the basis of the loaded voltage (step a). In the case of the pre-incandescent voltage less than the target pre-incandescent voltage Us, deviations ΔU1 and ΔU2 between the target pre-incandescent voltage Us and the real pre-incandescent voltages U1 and U2 applied to the glow ignition mechanism 14 are obtained (step b). On the basis of the deviations ΔU1 and ΔU2 obtained in the described step b, pre-incandescent continuous time corrected with a reference of the basic pre-incandescent continuous time and/or a pre-incandescent duty ratio raised for correction with a reference of the basic pre-incandescent duty ratio are obtained (step c). <P>COPYRIGHT: (C)2004,JPO

Description

  The present invention relates to a heating device, and more particularly to a method for controlling a glow ignition mechanism of a vehicle heating device.

  DE 32 48 412 A1 discloses a method for driving a glow plug of a vehicle heating device. In this driving method, the pre-glow duration of the glow plug is adjusted as a function of the voltage provided by the vehicle battery. The higher the voltage, the more preheated the glow plug is for a short time. Also, the lower the voltage, the longer the pre-glow time. This makes it possible to reach the glow plug temperature required to carry out the ignition process, independently of the voltage provided by the vehicle battery.

  It is known from DE 199 36 729 C1 to excite a glow plug with a constant, non-clocking voltage in order to preheat the glow plug in the starting phase of the vehicle heating device and bring it to the desired operating temperature as quickly as possible. The time for continuously energizing the glow plug depends on the on-board source voltage. The higher the onboard power supply voltage used, the shorter the time of continuous energization and therefore the shorter the time used for preheating.

DE 4446113 A1 discloses a method for controlling a glow plug. Here, the glow plug is controlled at a predetermined duty ratio to bring it to a predetermined temperature. That is, the used voltage is pulsed according to the duty ratio and applied to the glow plug. This duty ratio is selected depending on the supply voltage present, and as the supply voltage decreases, the duty ratio increases to a value of 100%.
DE3248412A1 DE 199367729C1 DE4446113A1

  It is an object of the present invention to improve the control method of the glow ignition mechanism of a heating device, in particular of a vehicle heating device, to reduce the load on the glow ignition mechanism and to optimize it.

The object is to provide a method of controlling a glow ignition mechanism of a heating device, particularly a vehicle heating device,
a) forming a target pre-incandescent voltage to be applied to the glow ignition mechanism with a basic pre-heat pulse duty ratio during the basic pre-heat interval based on the on-board voltage;
b) If the target pre-incandescent voltage is not reached, determine the deviation between the target pre-incandescent voltage and the actual pre-incandescent voltage applied to the glow ignition mechanism;
c) Based on the deviation determined in step b), the pre-heating duration corrected based on the basic pre-heating duration and / or increased and corrected based on the basic pre-heating duty ratio. The problem is solved by determining the preheating duty ratio.

  The main point of the method according to the invention is to adjust the voltage applied to the glow ignition mechanism in the pre-incandescent phase to an optimum target value for a given glow ignition mechanism. For such a target value, the basic preheating time and the basic preheating heat duty ratio are used to preheat the glow ignition mechanism in a predetermined manner. Between the desired value of the pre-heating voltage and the basic pre-heating time or the basic pre-heating duty ratio, the value of the pre-heating phase should be as short as possible, but the activation of the glow ignition function is overloaded, especially There is a close relationship that overheating should not occur.

  However, for example, in a vehicle, a large number of loads use electrical energy to reduce the on-board power supply voltage so that the target pre-incandescent voltage cannot be reached, so that a correspondingly reduced actual pre-incandescent voltage is applied to the glow ignition mechanism. Due to this fact, corrective measures are taken on the basis of existing deviations between the target value and the actual value of the marginal heating voltage. In this way, the desired temperature is reached at the end of the preheating phase, so that the reduced margin heating voltage and the reduced preheating power are compensated accordingly.

  In order to take into account external conditions, for example the ambient temperature, during the preheating of the vehicle heating device or the glow ignition mechanism, the basic preheating duration or / and the basic preheating duty ratio are determined by at least one operation whose operating parameter represents the ambient temperature. Set based on parameters. Thus, for example, when the external temperature is very low, a longer basic preheating time or a higher basic preheating heat duty ratio can be set than when the ambient temperature is high. It is also possible to take into account the temperatures present in the region of the heating device itself. If the heating device has to be shut down for a short period of time and is to be restarted, and if the temperature is relatively high, select a correspondingly short pre-incandescent phase with a correspondingly reduced pre-incandescent power. Can be.

  Further according to the invention, the application of the pre-incandescent voltage to the glow plug is interrupted when the deviation detected in step b) exceeds a predetermined limit value. When the predetermined voltage level cannot be reached, the correction means to be executed according to the present invention can be performed, for example, as follows. That is, the pre-glow duration corrected in step c) is obtained by calculating the correction term based on the deviation obtained in step b) and the addition of the correction term to the basic pre-glow duration, or in step c). The corrected basic preheating duty ratio is obtained by calculating a correction term based on the addition of the deviation obtained in step b) and the correction term to the basic preheating duty ratio.

  FIG. 1 schematically shows a heating system which can be used, for example, as a parking heater or a vehicle auxiliary heater. The heating system 10 has a heating device 12 generally indicated by 12. In the heating system 10, fuel air having vaporized or atomized fuel is mixed and burned. A glow plug 14 is provided in the combustion region to start this combustion. The glow plug is controlled by the control device 16 in the same manner as other system areas to be controlled of the heating device 12. The controller 16 is supplied by an on-board voltage network 18 to apply an excitation voltage to the glow plug 14. Based on the on-board voltage from the on-board voltage network 18, a voltage U is applied to the glow plug 14 at a duty ratio V when the glow plug 14 is to be excited and the combustion device 12 to start combustion therein. Here, in the marginal heating phase, the glow plug 14 should be brought to the desired temperature as quickly as possible, in which an increased preheating voltage is applied. This increased pre-incandescent voltage is reduced at the end of this pre-incandescent phase, as will be explained later.

  When the command to start the pre-incandescence is output at time t0, the control device 16 forms a pre-incandescence voltage based on the mounted voltage, and the pre-incandescence voltage is applied to the glow plug 14. Here, the value Us is selected as the pre-incandescent voltage target value. This value Us is adapted to the specific structural configuration of the respective glow plug 14 and ensures that this glow plug is not overloaded at least in normal operation. For this purpose, it is known to set the pre-incandescent voltage target value Us in a region of about 10V. The basic preheating time is also set in relation to the target value Us. During this basic preheating period, a preheating voltage of the target value Us is applied to the glow plug. FIG. 2 shows this basic preheating duration as a time interval between times t0 and tg. Similarly, the basic preheating heat duty ratio is selected in relation to the target value Us. As a result, the margin heating voltage U is applied to the glow plug 14 during the basic preheating time with the value Us and the basic preheating heat duty ratio. After the basic preheating time has elapsed, the voltage applied to the glow plug 14 can be reduced to a reduced ignition value Uz.

  Due to the large number of electrical loads present in modern vehicles, especially when the external temperature is low, the on-board voltage obtained from the on-board voltage network 18 is not sufficient and the voltage of the target value Us for the pre-incandescent phase must be reduced. You may not be able to get it. When a pre-incandescent command is generated in such a state, the controller 16 attempts to apply a sufficiently high voltage to the glow plug 14, but the actual pre-incandescent voltage actually applied is lower than the target value Us. Low. For example, the actually achieved pre-incandescent voltage is the value U1, which is lower than the target value Us by the difference ΔU1. If the glow plug 14 is preheated with the normal control parameters that do not change at such preheat voltage U1, there is a risk that the glow plug 14 will not be sufficiently preheated. Thus, if the desired value of the pre-incandescent voltage Us cannot be reached, at least one of the parameters, i.e. the basic pre-intensity duration and the basic pre-intensity duty ratio, is corrected according to the invention.

  FIG. 3 shows a characteristic map having a characteristic curve K. Here, a time correction term Δt is assigned to each voltage difference value ΔU. In the above case, if the actually applied pre-incandescent voltage U1 is lower than the target voltage Us by the difference ΔU1, a corresponding correction term Δt1 is extracted from the characteristic map shown in FIG. 3 and added to the basic pre-incandescent duration. Is done. As a result, as can be seen from FIG. 2, the end of the preheating is at the time point t1, at which point the voltage is reduced to the ignition voltage value U2.

  The greater the difference between the voltage actually applied to the glow plug 14 and the target value Us, the greater the time correction performed. Of course, this can also be done in the case of the duty ratio already mentioned. When the difference between the actual voltage and the target voltage increases, the duty ratio is adjusted so that the ON cycle increases or extends.

  However, the correction of the preheating duration or the preheating duty ratio can also be performed by calculating a correction term by which the correction coefficient is multiplied by the detected voltage deviation. This correction factor dictates how much the pre-glow duration should be extended per voltage deviation. The correction term thus obtained is added to the basic preheating time. The same applies, of course, to the duty ratio.

  This type of correction factor can be adjusted to the external ambient temperature, in the same way that the basic preheating duration and the basic preheating duty ratio can be selected depending on different parameters, for example the ambient temperature or the temperature of the area of the heating device 12. Can be selected depending on. The correction factor is substantially represented by the slope of the characteristic curve K in FIG. Thus, when the ambient temperature is high, or when the temperature in the region of the heating device 12 is high, a smaller correction is performed when the target voltage is lower than when a relatively low temperature is present.

  According to another embodiment of the present invention, when the difference between the target voltage and the actually applied pre-incandescent voltage exceeds a predetermined limit value, that is, when the actual voltage does not exceed the predetermined voltage limit value, the glow plug is used. The excitation of 14 is stopped completely, possibly forming a corresponding error alarm. This is because the heating device 12 cannot be ignited normally.

  In each case, the choice of various basic parameters, correction terms and correction factors results in disadvantageous conditions, i.e. very low ambient temperature at the beginning of the pre-incandescent phase, or very cold glow plug 14. Even in this case, it must be ensured that the required temperature can finally be reached within the time set for the glow ignition phase. On the other hand, the corrections made when the target voltage cannot be reached in the pre-incandescent phase must be made in such a way that an overload of the glow plug is prevented.

1 is a schematic diagram of the heating system of the present invention.

FIG. 2 is a diagram showing the time-dependent pre-incandescent voltage applied to the glow ignition mechanism of the system of FIG. 1.

4 shows a two-dimensional characteristic map forming a relationship between a voltage deviation and a correction term.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 10 Heating system 12 Heating device 14 Glow plug 16 Controller 18 Mounting voltage network

Claims (5)

In a method for controlling a heating device (12), in particular a glow ignition mechanism (14) of a vehicle heating device,
a) forming a target pre-incandescent voltage (Us) to be applied to the glow ignition mechanism with a basic pre-incandescent duty ratio for a basic pre-incandescent duration based on the mounting voltage;
b) When the target pre-incandescent voltage (Us) is not reached, the deviation (ΔU1, ΔU2) between the target pre-incandescent voltage (Us) and the actual pre-incandescent voltage (U1, U2) applied to the glow ignition mechanism (14) is calculated. Asked,
c) Based on the deviations (ΔU1, ΔU2) obtained in step b), the preheating time corrected based on the basic preheating time and / or the duty ratio based on the basic preheating heat duty ratio is increased. To obtain a corrected pre-incandescent duty ratio,
A method comprising:   The method according to claim 1, wherein the basic preheating duration and / or the basic preheating duty ratio are set based on at least one operating parameter.   3. The method of claim 2, wherein at least one operating parameter is representative of an ambient temperature.   4. The method according to claim 1, wherein the application of the pre-incandescent voltage to the glow ignition mechanism is interrupted if the deviation determined in step b) exceeds a predetermined limit value.   The pre-incandescent duration corrected in step c) is calculated based on the deviations (ΔU1, ΔU2) obtained in step b) and the addition of the correction term to the basic pre-incandescent duration, based on the correction terms (Δt1, Δt2). The basic preheating duty ratio determined by calculation and / or corrected in step c) is based on the deviation (ΔU1, ΔU2) determined in step b) and the addition of the correction term to the basic preheating duty ratio. 5. The method according to claim 1, wherein the method is determined by calculating a correction term.

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