JPH09112396A - Method and equipment for controlling idling of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively prevent the occurrence of a sharp drop in engine speed at the time of switching on a power consumption device having no direct information on an idling control operation mode by correcting an ignition angle as a function of a battery voltage change for controlling the idling operation of an internal combustion engine. SOLUTION: The actual voltage of a battery is measured with a measurement device 26 and supplied to a gradient forming unit 72 for a control unit 10 via a line 24. The gradient forming unit 72 finds the gradient of the measured battery voltage and feeds the value thereof to a threshold value state 76. Then, this threshold value stage generates a signal for closing a switch element 68 via a line 78, when the gradient exceeds the prescribed limit value, and adds the preset value for correcting an ignition angle as a function of a battery voltage gradient, to the output signal of an integrating element 54 via a line 66. As a result, a sharp engine speed drop at the time of switching on a power consumption device can be effectively prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and device for controlling idling of an internal combustion engine.

[0002]

2. Description of the Prior Art A method of this kind and a device of this kind are known from DE-A 38 32 727. Here, during idling, the idling speed of the drive unit is controlled so that the battery voltage is controlled to a predetermined target value. This target value is given as a function of the battery voltage by choosing the characteristic curve appropriately. In addition, other characteristic curves or fixed values are provided for adjusting the idling speed, these other characteristic curves or fixed values being switched on for large consumer devices such as air conditioners, transmissions, etc. Sometimes increase idling speed. For these consumer information, corresponding inputs are provided to the control unit for controlling the idling.

In modern internal combustion engines, it is required to further reduce the idling speed in order to reduce the fuel consumption during idling. At low idling speeds, in combination with normal generator control, when switched on to an electricity consuming device that does not have an input to the control unit (e.g. rear window glass overheat, front window glass overheat, etc.), It can cause a sudden drop in rotation speed.

Therefore, it is proposed in US Pat. No. 505446 to increase the air supply to the internal combustion engine as a function of the time curve of the battery voltage. This method is based on the fact that when the electricity consuming device is switched on, the battery voltage drops sharply.
By evaluating this voltage drop when the electricity consuming device is switched on, the idling of the internal combustion engine can be sufficiently adjusted. In this case, the battery voltage time curve is determined by evaluating the difference between the battery voltage values at two different times.

In the known method, the dynamic characteristics of the idling control are not sufficient, since on the one hand a very accurate battery voltage measurement is required and on the other hand the air supply to the internal combustion engine is mainly regulated. That is the problem.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an idling control method for an internal combustion engine, which effectively prevents a sudden decrease in the rotation speed when a switch is turned on to an electric power consumption device for which there is no direct information regarding the operating state. This is the subject of the invention.

[0007]

SUMMARY OF THE INVENTION In an internal combustion engine, the battery voltage is measured and its change is determined, and the air supply to the engine is modified in a direction to reduce this change as a function of the change in battery voltage. In the idling control method, the ignition angle is corrected as a function of the change in the battery voltage.

[0008]

FIG. 1 shows a control unit 10 including at least one microcomputer (not shown).
Is shown. The control unit 10 or the microcomputer is connected to the input lines 16 to 18 from measuring devices 12 to 14 for operating variables of the internal combustion engine and / or the vehicle.
Is supplied. An input line 20 leads from the rotational speed sensor 22 to the control unit 10 or the microcomputer, an input line 24 leads from the battery voltage measuring element 26, and an input line 28 leads from the measuring element 30 of the air supply to the internal combustion engine. ing.

The control unit 10 or the microcomputer operates via an output line 32 a setting element 34 for adjusting the air supply to the internal combustion engine, for example a throttle valve or a valve in a bypass pipe bypassing the throttle valve. . The adjustment of the ignition angle of the individual cylinders of the internal combustion engine by the control unit 10 or the microcomputer is indicated by the output line 36.

The control unit 10 comprises, in a preferred embodiment, the following elements which represent the program parts or program steps of the calculation program of at least one microcomputer. In other embodiments, the arrangement of these components can also be considered as components in digital or analog circuit technology.

Input lines 16 to 18 are supplied to the setpoint value generator 38, and an output line 40 of the setpoint value generator 38 leads to a comparison stage 42. The line 20 is also supplied to the comparison stage 42. The output line 44 of the comparison stage 42 branches into lines 48 and 50 and, in the preferred embodiment, also into line 46. The line 50 leads to an amplification element and / or a differentiation element 52, while the line 48 leads to an integration element 54. Elements 52 and 54
Form a controller which operates in a PI or PID control scheme in the preferred embodiment. The output line 56 of the element 52 leads to an addition stage 58, which is further supplied with a line 60 from a second addition stage 62. This second summing stage 62 is supplied with the output line 64 of the element 54 as well as the line 66, the line 66 coming from the memory element 70 via the switch element 68. The input line 24 of the control unit 10 leads to a gradient former 72, the output line 74 of the gradient former 72 leads to a threshold stage 76,
Threshold stage 76 operates switch element 68 via output line 78. A line 80 leads from the line 74 to the characteristic curve element 82, and an output line 84 of the characteristic curve element 82 leads to the filter element 86. In one embodiment, filter element 86 is provided with line 46.
The output line 88 of the filter element 86 leads to the addition stage 94. An input line 96 is supplied to the addition stage 94 from the characteristic curve group element 98, and the characteristic curve group element 98 is supplied with the line 2
Lines 99 as well as lines 28 originating from 0 are supplied. The output line of summing stage 94 is shown as output line 36 of control unit 10.

The setpoint generator 38 comprises a set of characteristic curves, a set of characteristic curves, a table or a calculation program by means of which the setpoint generator 38 can, as a function of the input variables supplied to it, setpoint values for idle adjustment, A target value for the idling rotational speed is preferably formed. In this case, the supplied input variables are preferably engine temperature, air conditioner switch, etc. The setpoint values determined by the setpoint value generator are compared in the comparison stage 42 with the respective actual values, preferably the engine speed, in order to form the control deviation. The difference between the desired value and the actual value is fed to the controller, in this case elements 52 and 54. In the preferred embodiment, these elements (controllers) 52,
Reference numeral 54 designates a PI controller whereby element 52 amplifies the supplied control deviation and element 54 integrates the supplied control deviation. In the summing stage 58, both determined signals are combined with one another into one control output signal, in which case the signal of the integrating element 54 is modified in the summing stage 62 as will be described later. The control output signal is used via line 32 to regulate the air supply to the internal combustion engine. In this case, the elements 52, 54 act to bring the actual value closer to the determined target value.

In addition to the configuration of the controller shown, in another embodiment, for example a so-called PID controller, or a pre-control as a function of the rotational speed gradient or a pre-control as a function of a variable indicating the load of the internal combustion engine. Other control types are used, such as controllers with In another embodiment, the control unit of FIG. 1 shows a torque control circuit, a power control circuit, an engine load control circuit or an air control circuit.

The actual battery voltage is measured by the measuring device 26 and the actual battery voltage is supplied to the control unit 10 via the line 24. In the gradient generator 72 of the control unit 10, the gradient of the battery voltage is determined from the measured battery voltage. In the preferred embodiment, this is done by forming the difference between two successive measurements until the battery voltage rises again and adding the difference. At this time, each of the obtained sums gives the gradient of the battery voltage in consideration of the number of cycle time points, and the gradient of the battery voltage can be surely and accurately obtained in this manner. In another advantageous embodiment, the slope of the battery voltage is determined from the sum of the determined number of difference values. The calculated voltage slope value is provided to threshold stage 76 to regulate the air supply. When the (negative) slope exceeds a predetermined (negative) limit value, the threshold stage 76
Generates a signal on line 78 to close the switch element 68. In this way, the output signal of the integration element 54 via the line 66 is added with a predetermined value for increasing the air supply amount and for avoiding an expected rapid decrease in the rotation speed.

In a preferred embodiment, this value is a function of operating variables (eg, speed, temperature, load, air supply and / or slope of battery voltage).

When the slope of the battery voltage exceeds the threshold value, the added value is added once to the integrator of the controller. The idling controller then compensates for the additional load on the consumer within the control function.

In order to avoid always triggering the switch every cycle of the slope, in the preferred embodiment the counter is started after the threshold is first exceeded. As long as the counter is running, the switch remains closed and raising the threshold, preferably doubling, avoids the formation of a trigger signal from the switch at each cycle point. As a result, a hysteresis characteristic is formed.

In addition to raising the output signal of the integration element 54,
In another embodiment, the output signal of the controller itself (line 32) is raised.

In addition to adjusting the amount of air supplied to the internal combustion engine,
Advantageously, the method according to the invention further modifies the ignition angle in order to improve the speed of adjustment. As is known, in the characteristic curve group element 98, the basic ignition angle is formed and optionally modified from the values of the engine speed and the engine load supplied. In addition, the method of the present invention provides the characteristic curve element 82 with the slope of the battery voltage and reads the ignition angle correction value from the characteristic curve element 82. In general, the characteristic curve gives an increased regulation of the ignition angle in the direction of advancing the ignition timing when the (negative) slope increases. The value read from the characteristic curve is supplied to the filter element 86, where the correction value is reduced by a predetermined time function, preferably a linear or exponential time function. The thus modified correction value is added to the formed ignition angle (addition stage 94), and the ignition angle of each cylinder is controlled so as to suppress the decrease in the battery voltage.

In a preferred embodiment, the ignition angle adjustment is prohibited when the gradient of the battery voltage exceeds the threshold value for air amount control as described above. Furthermore, in a preferred embodiment, the correction value is reset to the value 0 when the difference between the target value and the actual value is negative, i.e. when the actual value is greater than the target value. However, it should be noted that in this case the ignition angle adjustment is effective for at least a certain number of ignitions.

The functional method of idling control will be described in detail with reference to the flowcharts of FIGS.

The determination of the battery voltage slope is shown in FIG. After the program portion starts at a predetermined time point, in the first step, the actual battery voltage value U
Batt (I) is read (step 100). In a subsequent step 102, the difference Δ between this battery voltage value UBatt (I) and at least one battery voltage measurement UBatt (I-1) determined in the preceding, preferably previous program run.
(I) is formed. Subsequent inquiry step 1
At 04, it is checked if the determined difference is greater than zero. If this is affirmative, the gradient Gr of the battery voltage
adU is set to 0 and, if not, the battery voltage slope is formed from the sum of the determined difference values as well as the predetermined number of preceding difference values, taking into account the number of time points I. (Step 108). The program part is then terminated and repeated after a predetermined time.

To determine the slope of the battery voltage, the cycle differences are added. This is done until the battery voltage rises again. In this way, a reliable and accurate determination of the gradient of the battery voltage is made and thus the switch-on process of the electricity consuming device is specified.

FIG. 3 illustrates the process of adjusting the air supply as a function of the determined voltage gradient. After the program part has started at a given time, in a first step 200 the voltage gradient GradU is read and the correction value Qkorr is set to zero. In the following step 202, the voltage gradient GradU is compared with a predetermined threshold value GradU0. When the (negative) slope value exceeds the (negative) threshold, step 204 starts a counter and step 206 raises the threshold by a predetermined (negative) value Δ. At this time,
The correction value Qkorr for the air supply amount is calculated in step 208.
Is set to the value A by. The program part is then terminated and repeated after a predetermined time.

If the value of the voltage gradient falls below a predetermined threshold value, step 210 checks whether the counter state Z> 0. If this is the case, step 2
12 reduces the counter state by 1 and sets the mark to the value 1. If in step 210 the counter value has the value 0, then step 216 sets the counter to the value 0 and sets the slope threshold to the initial value G.
radU0 is set and the mark is set to the value 0. The program part is then terminated and repeated after a predetermined time.

A preferred method of calculating the control output signal Q is shown in FIG. After the program portion has started at a predetermined time point, in a first step 300, the set rotational speed target value Nsoll and the measured rotational speed Nist of the engine are read. In the following step 302, the difference ΔN is formed from these values. In the following step 304, the proportional part QP and the integral part Q of the control output signal as a function of the difference ΔN.
I is required. In the subsequent step 306,
The obtained integral part QI is modified by addition with the correction value Qkorr obtained by the method shown in FIG. It is formed. The program part is then terminated and repeated after a predetermined time.

In addition to the above adjustment of the air supply, the ignition angle is modified in order to improve the dynamics of the idling control when the electricity consuming device is switched on. This corrects the voltage drop very quickly via the ignition angle, and the temporary demands that are subsequently set by the consumer are taken over and responded by adjusting the air supply, in this case the calculation of the integral part of the controller. To be done.

A preferred method for determining the ignition angle correction is shown in FIG. This program part is also started at a predetermined time. First step 400
At, the rotational speed deviation ΔN and the voltage gradient GradU obtained by the method shown in FIGS. 2 to 4 are read. In the following step 402, it is determined whether the mark set or reset in the program part shown in FIG. 3 has the value 1, that is to say the correction of the air supply to the internal combustion engine due to a sharp voltage drop. Is checked. If yes, step 4
14 continues. If not, step 404 determines the basic value ZWkorr0 for ignition angle correction as a function of the slope of the battery voltage from the predetermined characteristic curve. In this case, in a preferred embodiment, this characteristic curve is
An ignition angle correction value that modifies the ignition angle in the direction of advancing the ignition timing is selected to increase with an increase in the slope of the (negative) battery voltage. After step 404, step 4
The counter Z1 is started by 06, and the counter Z1
Is incremented by 1 in the following step 408. Then, in the following inquiry step 410, it is checked whether the rotational speed deviation ΔN <0, that is, whether the actual value exceeds the target value. If this is the case, step 412 checks if the counter state is greater than a predetermined maximum counter state. If this is the case, step 414 causes step 40
Ignition angle correction value ZWkor as in the case of 2
r is set to the value 0. This means that when the rotational speed deviation is negative, the ignition angle correction is set to 0 after the ignition angle correction is performed by the predetermined number Z1max of ignitions. If the control deviation is not less than 0 or the counter state is not greater than the maximum value, step 416 forms the ignition angle correction value ZWkorr starting from the correction basic value and lower by a value Δ which is a function of the counter state. To be done. In this step, a preferably linear or exponential decay of the ignition angle correction value takes place. Step 41
In step 418 following 4 or 416, it is checked whether the ignition angle correction value is zero. If this is not the case, the program part is repeated from step 408, and if yes, a fresh start is made from step 400 at a given time.

When the air supply amount is corrected (mark is set) or after the control deviation is smaller than 0 and the ignition angle is corrected for a predetermined number of ignitions, other ignition angle Modifications are prohibited.

FIG. 6 illustrates the ignition angle modification in the preferred embodiment. After the program portion starts at a predetermined time point, in the first step 500, the operating variables, that is, the rotation speed Nist, the engine load Qist, and the ignition angle correction value ZWkorr are read. In the following step 502, the ignition angle ZW is read from the preprogrammed characteristic curves as a function of rotational speed and engine load, followed by step 5
At 04, the ignition angle ZW is corrected by the sum with the correction value and output. The program part is then terminated and repeated after a predetermined time.

FIG. 7 shows the operation of the method according to the invention in which the time diagram of the signal with respect to the battery voltage (FIG. 7a), the time diagram of the signal with respect to the ignition angle (FIG. 7b) and the time diagram of the signal with respect to the air supply amount. (Fig. 7c). Starting from steady idling, the consumer is switched on at time T0. The battery voltage drops, and the ignition angle is adjusted in the advancing direction after time T0. When the battery voltage gradient exceeds the predetermined threshold value at the time point T1, the air supply amount is increased by the predetermined value after the time point T1. The ignition angle is reset accordingly.
After a predetermined time has elapsed (the battery voltage rises again as a result of the adjustment) at time T2, the air supply amount is controlled by the controller after time T2.

[0032]

[Effect] By evaluating the slope of the battery voltage, it is determined that the electricity consuming device is switched on. In this case, it is advantageous that the slope of the battery voltage is determined by adding the differences of several cycles, thus allowing a reliable and accurate detection of the switching on of the consumer.

The method according to the invention advantageously adjusts not only the air supply to the internal combustion engine, but also the ignition angle of the internal combustion engine. This improves the quickness of the idling control, since an early detection of the switch-on of the electricity consuming device due to the gradient of the battery voltage is ideally supplemented by a quick reaction due to the ignition angle.

When the air supply amount is increased by detecting the switch-on of the electricity consuming device, the ignition angle is not corrected, and the air supply amount can be newly corrected only after the elapse of a predetermined time. It is advantageous. In this way, the air supply or the ignition angle is reliably controlled when the electricity consuming device is switched on, thus effectively preventing an expected sudden drop in rotational speed.

[Brief description of the drawings]

FIG. 1 is an overall block circuit diagram of an idling control device.

FIG. 2 is a flow chart of a microcomputer program for determining a battery voltage gradient in a preferred embodiment of the present invention.

FIG. 3 is a flow chart of a microcomputer program for adjusting an air supply amount as a function of a determined voltage gradient in a preferred embodiment of the present invention.

FIG. 4 is a flowchart of a microcomputer program for calculating a control output signal according to a preferred embodiment of the present invention.

FIG. 5 is a flow chart of a microcomputer program for determining an ignition angle correction in a preferred embodiment of the present invention.

FIG. 6 is a flow chart of a microcomputer program for correcting the ignition angle in the preferred embodiment of the present invention.

7 is a time diagram showing an example of an operating method according to the present invention, FIG. 7a is a time diagram of a signal with respect to a battery voltage, FIG. 7b is a time diagram of a signal with respect to an ignition angle, and FIG.
c is a time diagram of a signal with respect to the air supply amount.

[Explanation of symbols]

10 Control unit 12 ... 14 Measuring device (operating variable) 16 ... 18, 20, 24, 28, 32, 36, 40,
44, 46, 48, 50, 56, 60, 64, 66, 7
4, 78, 80, 84, 88, 92, 96, 99 Line 22 Rotation speed sensor 26 Battery voltage measuring element 30 Air supply amount measuring element 34 Setting element 38 Target value former 42 Comparison stage 52 Amplifying element (differential element) 54 Integration element 58, 62, 94 Addition stage 68 Switch element 70 Memory element 72 Gradient generator 76 Threshold stage 82 Characteristic curve element 86 Filter element 98 Characteristic curve group element A Qkorr setting value GradU Battery voltage gradient GradU0 Battery voltage gradient Threshold value Nist Measured value of engine speed Nsoll Target value of engine speed Q Control output signal (air supply amount) QI Integral part of control output signal Qist Engine load Qkorr Corrected value of control output signal QP Proportion of control output signal Partial UBatt (I) Battery voltage (Measurement) value Z1max maximum counter state ZWkorr Ignition angle correction value ZWkorr0 Basic value of ignition angle Z counter (air supply amount adjustment) Z1 counter (ignition number) Δ (I) Battery voltage value deviation ΔN Rotation speed deviation

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location F02D 45/00 312 F02D 45/00 312S (72) Inventor Klaus-Dieter Nusser Federal Republic of Germany 71701 Schwiebe Rudingen, Hermann-Essich Schutrasse 104 (72) Inventor Karlheinz Riedel, Federal Republic of Germany 71665 Weihingen, Hildenstraße 5 (72) Inventor, Vera Lehner, Federal Republic of Germany 71732 Tam, Babe Ringer Weg 4 (72) ) Inventor Guido Ehlers Germany 70825 Korntal-Münchingen, Stalenweg 2

Claims (11)

[Claims] 1. A method for controlling the idling of an internal combustion engine, in which the battery voltage is measured and its change is determined, and the air supply to the internal combustion engine is modified in the direction of reducing this change as a function of the change in the battery voltage. In Id., A method of controlling idling of an internal combustion engine, wherein the ignition angle is corrected as a function of a change in battery voltage. 2. The method of claim 1, wherein the change in battery voltage is determined by summing the difference in battery voltage between two cycle time points for a plurality of cycle time points. 3. When the air supply amount is corrected,
Method according to claim 1 or 2, characterized in that there is no correction of the ignition angle. 4. A characteristic curve is provided for modifying the ignition angle, from which the ignition angle modification value is read as a function of the gradient of the battery voltage. Method. 5. The method according to claim 1, wherein the ignition angle correction is not performed when the difference between the target rotational speed and the actual rotational speed is less than zero. 6. The difference between the target rotation speed and the actual rotation speed is 0.
6. The method of claim 5, wherein the ignition angle correction is not performed when the ignition angle correction is performed for a smaller number of ignitions. 7. The method according to claim 1, wherein the correction of the air supply amount is performed when the gradient of the battery voltage exceeds a predetermined threshold value. 8. Method according to claim 1, characterized in that the correction of the air supply is carried out by adding a fixed value to the signal controlling the air supply. 9. The method of claim 8 wherein the fixed value is a function of operating variables. 10. The method according to claim 1, wherein the threshold value of the battery voltage is not further detected within a predetermined time after the first threshold value of the battery voltage exceeds the threshold value.
Either way. 11. A control unit for adjusting the amount of air supplied to an internal combustion engine, to which a value indicative of a battery voltage is supplied, a slope former for determining a battery voltage change from a measured value with respect to the battery voltage, and a slope of the battery voltage. A controller for adjusting the air supply to the internal combustion engine in the direction of decreasing the gradient of the battery voltage as a function of the electronic control unit, the electronic control unit further comprising at least an ignition angle of the internal combustion engine. And a correction device that adjusts the ignition angle in a direction that reduces the slope of the battery voltage as a function of the slope of the battery voltage.