JPH02305375A - Method and device for controlling glow plug temperature - Google Patents

Abstract

PURPOSE: To assuredly maintain a glow plug within a specific range by finding target electric power upon adding the electric power fluctuation part to a basic electric power value with regard to a reference operating point from which respective operating parameters take the reference value. CONSTITUTION: With regard to those calculating necessary target electric power to keep a glow plug 12 in a temperature within a specific range by a controller 10 based on such operating parameter as a number of revolutions N, an engine temperature TW, an intake temperature TL, an injection starting time SB, and a fuel injection amount QK, the controller 10 detects the difference of value between the actual value of the operating parameter and the corresponding reference value and calculates the electric power fluctuation of the respective operating parameter by using constant corresponding to the difference of value. The target electric power is formed by all inputted operating parameters taking respective references, flowing a basic electric power value with respect to the reference operating point so that the glow plug 12 may be in a preferable temperature, and correcting the basic electric power value by using all electric power fluctuation elements.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a glow plug temperature control method and apparatus, and more particularly to a glow plug used for ignition in the starting mode and warm-up mode of a self-ignition internal combustion engine. The present invention relates to a method and apparatus for controlling the temperature of.

[Prior Art] A method and a device for controlling the temperature of a glow plug are disclosed in German Patent Publication No. 3502966 (US Pat. No. 46587).
No. 22). The temperature of the glow plug is controlled according to at least one operating parameter of the internal combustion engine. In that case, a target power required to bring the glow plug to a temperature within a predetermined range is calculated using predetermined operating parameters. The predetermined temperature range is, for example, 90
It is 0°C to 1050'c. As operating parameters, fuel supply amount, injection period, injection start timing, etc. are particularly used, and in addition, rotational speed and various temperatures are also used. The above-mentioned publication discloses how to form a relationship between the electric power supplied to the glow plug and the values of the operating parameters used.

[Problems to be Solved by the Invention] An object of the present invention is to provide a glow plug temperature control method that can reliably maintain the temperature of the glow plug within a predetermined range. Furthermore, it is an object of the invention to provide a device for carrying out the above method.

[Means for Solving the Problems] In order to solve the above problems, the method of the present invention employs the features set forth in claim 1, and the apparatus of the present invention employs the features set forth in claim 6. features are adopted.

[Effect 1] According to the method of the present invention, the target power is calculated based on the basic power value. This basic power value is determined with respect to a reference operating point at which all input operating parameters take reference values. The power fluctuation amount is added to this basic power value. The power fluctuation amount is calculated by first finding the difference between the actual value of each input operating parameter and its corresponding reference value. The difference value is then multiplied by a constant. When adding the power fluctuation amount and the basic power value, it is considered whether the corresponding difference value is positive and results in an increase in power or a decrease in power. This consideration is taken by choosing the sign accordingly when adding, or by defining the sign of the relevant constant accordingly.

According to the method of the invention by using a reference operating point:
An advantage is obtained that there is no need to change the basic power value in a region around this operating point. However, the basic power value is set so that the glow plug reaches a desired temperature at the reference operating point. The reference operating point is preferably set for a driving state in which ignition assistance by a glow plug is absolutely necessary in order to keep the engine running quietly with as little soot as possible. When an internal combustion engine employing the method of the present invention rotates, a small change in the basic power value occurs, so that the calculated power correction amount is exactly the amount of change originally required to precisely maintain the desired temperature. The desired glow plug temperature is accurately maintained without having to accommodate As the value of the operating parameter at the actual operating point deviates from the value at the reference operating point, the possibility that the power correction amount originally required to maintain the desired temperature and the calculated power correction amount will deviate increases. However, even if the error increases as the distance from the reference operating point increases, the increase in error usually does not become a major problem.

It is more effective to calculate not only the power fluctuations that do not depend on the rotational speed but also the power fluctuations that depend on the rotational speed with respect to the input operating parameters.

For this purpose, the value of the difference between the actual rotational speed and the reference rotational speed is determined, and the difference value between the operating parameters and the rotational speed is multiplied by a constant. If the actual rotational speed deviates significantly from the reference rotational speed, the value of the power fluctuation that depends on the rotational speed can be compared with the power fluctuation that does not depend on the rotational speed. Regarding the influence of the fuel injection amount, corrections that depend on the rotational speed have a particularly strong effect. On the other hand, in order to eliminate the influence of the fuel injection start timing, only a small rotational speed-dependent correction is required.

The device according to the invention is equipped with a driver circuit and various means for carrying out the above-mentioned calculation process. These means are preferably included in a control device having a microprocessor. The microprocessor outputs the target power value,
Based on this, the driver circuit operates at the target power of the glow plug.

[Example] The present invention will be described in detail below using examples shown in the drawings.

The block circuit diagram shown in FIG. 1 shows a control device IO, a driver circuit 11 and a glow plug 1 formed as a resistor.
2 is shown. The control device 1° has operating parameters,
That is, in this embodiment, the rotation speed N, engine temperature (cooling water temperature) TW, intake air temperature TL, injection start timing SB
and fuel injection m Q K are input. The target power P-3 to be input to the driver circuit 11 is formed by the control device 10 from these actually input values and the values stored in the memory. The driver circuit 11 uses this target power and battery voltage UB to determine the clock duty.
The ratio is calculated, the glow plug 12 is driven at this duty ratio, and the desired target power P-8 is supplied to the glow plug.

The apparatus shown in FIG. 1 performs the processing described using FIG. 2. This process includes seven steps 81 to s7, among which steps 81 to s6 are performed by the control device 1.
Step s7 is performed in driver circuit II.

When the process shown in FIG. 2 starts, first, the basic power, operating parameters, evening reference value, and constants are set to predetermined values. For example, in the case of a 2500cc diesel engine, the operating parameters and their standard values are as follows.

N B near 50 rpm = reference rotation speed value TW B knee 5°C - reference cooling water temperature value TL B knee 16°C 2 reference intake air temperature value SBB knee 6° KW = reference injection start time (crank before Doi point Shaft angle) value QK B: 4 mg = standard fuel injection amount value To drive the internal combustion engine accurately with these values.

The glow plug must be supplied with precise power to bring it to exactly the desired temperature, for example l 000'C. In the following explanation, this power will be referred to as the basic power P
It's called G.

Step sl of this embodiment? The constants set in are as follows.

K N: 2.7X10-"V/min Constant to compensate for the influence of rotation speed K TW near, 3X10-3V/'C = Constant to compensate for the influence of cooling water circulation K TW N knee 14.2xlo- 6V/℃ min = Constant K that corrects the effect of cooling water temperature depending on rotation speed TL knee 11.9 x 10-3V/'C = Constant K that corrects the effect of intake air temperature TL N knee 19.1 x 1O-6V/℃ minutes = constant K SB:0.15V/'KW = constant K SB that corrects the effect of intake air temperature dependent on rotational speed N:0 2 Effect of injection start timing dependent on rotational speed Constant K to correct QK knee 32.1x10-3V/mg = Constant K to correct the influence of fuel injection amount QK N knee 126.4x10-6V/mg min = Correct the influence of fuel injection amount depending on rotation speed In the constant step S2, the values of the operating parameters are measured, and in this embodiment, the rotation speed N, the cooling water temperature TW,
The values of intake air temperature TL, injection start timing SB, and fuel injection amount QK are measured. In step s3, the difference between the actual value and the reference value of each operating parameter is formed as shown in the following equation.

TW D=TW-TW B TL D=TL-TL B SB D=SB-3B B QK I)=QK-QK B In step S4, the power fluctuation amount is calculated. That is, for each input operating parameter, a power value to be added or subtracted is calculated, and the effect of an error in power generated in the glow plug due to deviation of each value of the operating parameter from the reference value is compensated for. This calculation is performed, for example, with respect to the rotational speed according to P D N =K NxN D , and calculations are performed with respect to other operating parameters according to a similar formula.

In step s5, power fluctuations depending on the rotational speed are calculated for each operating parameter used. No calculations of this kind are made for the rotational speed itself. This is because, as shown in step S4, the power fluctuation is calculated as a power fluctuation that depends on the rotation speed. The following calculation formula is used to calculate the influence of cooling water temperature depending on the rotation speed, but similar formulas are used for other operating parameters.

P D TW N= K TW NxTW DxN DFurthermore, in step s6, the basic power PG and the power variation P'
The target power PS is calculated from the sum of D according to the formula shown below. In this case, the power fluctuation component includes all components of the power fluctuation component that does not depend on the rotation speed and the power fluctuation component that depends on the rotation speed calculated in steps s4 and 85, respectively.

P S=PG+ΣPD As already explained, the calculated target power P-8 is supplied to the driver circuit 1■. This process is performed in step s7.
It will be held in In step s7, a pulse duty ratio for controlling the glow plug is calculated using the battery voltage UB and the target power PS. This last step is a conventional step.

As is clear from the explanation of the scale, if the reference operating point changes due to fluctuations in the reference values of the operating parameters used, the amount of power required to obtain the temperature obtained at the reference operating point will also change. . The reference operating point can be selected arbitrarily. Preferably, the reference operating point is defined at an operating point that causes problems in the rotation of the four-stroke engine with the operating parameters used, ie, an operating point that promotes uneven rotation and soot production. For example, operating points at particularly low temperatures or low rotational speeds are used. The power required to obtain a glow plug temperature that allows the engine to run optimally without shortening the life of the glow plug is specified for this reference operating point, so when this operating point is reached in actual operation. Optimal conditions are achieved.

This also applies to operating points close to the reference operating point in question. The further away from the reference operating point, the greater the possibility that it will not be possible to calculate the target power that corresponds to the power actually required for the optimal glow plug temperature. However, if the reference operating point is determined for a relatively low rotational speed and temperature, there will be fewer operating points for even lower rotational speeds and temperatures. Therefore, only a small amount of error occurs. On the other hand, at operating points where the engine speed and temperature are higher, the error will be larger (although there is a possibility that it will become a problem, it is not a serious problem. This is because when the temperature and speed are relatively high, the engine This is because there are not many problems with driving characteristics.

Furthermore, the power to be supplied is also related to how the glow plug temperature is set. As is clear from the foregoing discussion, for many internal combustion engines the glow plug temperature is preferably around 1000°, but for example 900° or 1
Glow plug temperatures of 100° are also possible. Basically, it is preferable to set the temperature as high as possible, but higher temperatures shorten the lifespan, so the decision is made based on this balance.

From the sign of the constant described above, it can be understood that as the rotational speed increases, the target power also increases, and as the cooling water temperature or the intake air temperature increases, the target power decreases. Instead of using the sign of the constant, the direction of the correction can also be determined by selecting a different sign during the addition or by subtracting the actual value of the operating parameter from the reference value.

[Effects of the Invention] As is clear from the above description, according to the present invention, it is possible to obtain a glow plug temperature control method and apparatus that can reliably maintain the temperature of a glow plug within a predetermined range.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram of a device for controlling the temperature of a glow plug, and FIG. 2 is a flowchart showing a method for controlling the temperature of a glow plug. io--Control device 11--Driver circuit 12--Glow plug Fig, 2

Claims (1)

[Claims] 1) A method for controlling the temperature of a glow plug in accordance with operating parameters of an internal combustion engine, the method comprising: controlling the temperature of a glow plug in accordance with operating parameters of an internal combustion engine, the target being necessary to bring the temperature of the glow plug within a predetermined range using input operating parameter values; In a glow plug temperature control method that calculates electric power, applies voltage to the glow plug, and supplies the calculated target electric power to the glow plug, the difference value between the actual value of each input operating parameter and the corresponding reference value. , and calculates the power fluctuation for each input operating parameter by calculating using the difference value and the corresponding constant, and all the input operating parameters take their respective reference values and the glow plug A basic power value is formed with respect to a reference operating point at which a desired temperature is achieved, and the basic power value is corrected using all the power fluctuation components, thereby forming a target power. Glow plug temperature control method 2) The basic power value is corrected by adding the basic power value and all power fluctuations, and if the difference value is positive, the power fluctuations that would result in an increase in power are positive. 2. A method as claimed in claim 1, characterized in that the power fluctuations which, if the difference value is negative, result in a power reduction, are added negatively. 3) The method according to claim 1 or 2, characterized in that at least the rotational speed is used as the input operating parameter. 4) Regarding operating parameters other than the rotation speed, power fluctuations depending on the rotation speed are also calculated and used as the total power fluctuation.
The method described in section. 5) form a value of the difference between the actual rotation speed and the reference rotation speed;
5. The method according to claim 4, wherein power fluctuations depending on the rotational speed are calculated by performing calculations using a difference value between operating parameters, a difference value between the rotational speed, and a constant. 6) In a glow plug temperature control device that calculates the target power required to bring the glow plug to a predetermined temperature range using input operating parameter values and controls the temperature of the glow plug according to the operating parameters of the internal combustion engine. , a driver circuit (11) for applying a voltage to the glow plug and supplying the calculated target power to the glow plug; and means for forming a difference value between the actual value of each input operating parameter and its corresponding reference value. (10); means (10) for calculating power fluctuations for each input operating parameter by calculating using the difference value and a constant corresponding thereto; and calculating a basic power value using all power fluctuations. A glow plug temperature control device comprising: means (10) for correcting.