JP4454085B2 - Internal combustion engine control method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an internal combustion engine control method and apparatus.
[0002]
[Prior art]
In state-of-the-art internal combustion engine controllers, there are operating conditions in which the efficiency of the internal combustion engine is lower than in other operating conditions. For example, in this operating state, which occurs during rapid heating of the catalyst, the charge amount of the internal combustion engine, that is, the air supply amount to the internal combustion engine is increased, and the ignition angle is shifted in the delay direction in order to keep the torque substantially constant. The Due to the increase in the air supply amount that reduces the efficiency in the operating state, the negative pressure in the intake pipe is reduced. However, in order to supply the negative pressure to the pressure reservoir of the vehicle brake force amplifier, it is necessary that the negative pressure of the intake pipe is high. Therefore, in some embodiments, for example, when the brake operation is performed a plurality of times during the operation process as described above, the reservoir pressure for reliable operation of the brake force amplifier is reduced due to the low negative pressure of the intake pipe. It may not be secured.
[0003]
An internal combustion engine control device that reduces the efficiency of the internal combustion engine in the above operating state is described, for example, in German Patent Publication No. 19618893 as an example of a torque-based control device.
[0004]
[Problems to be solved by the invention]
It is an object of the present invention to improve the internal combustion engine control device so that a negative pressure necessary for the operation of the brake force amplifier is ensured even under adverse conditions.
[0005]
[Means for Solving the Problems]
The object is to provide a control method for an internal combustion engine that is operated at a reduced efficiency in at least one operating state than in normal operation, in which at least one operating state in which the efficiency is reduced, the negative pressure on the pressure reservoir is reduced. This is achieved by the method for controlling an internal combustion engine according to the invention, characterized in that the efficiency is changed in a direction to improve the efficiency as a function of the characteristic value of the internal combustion engine to be adjusted.
[0006]
The above-mentioned problem is also provided in a control device for an internal combustion engine having a control unit for operating the internal combustion engine with reduced efficiency in at least one operating state as compared with normal operation. The internal combustion engine according to the invention, characterized in that it has means for changing the efficiency in a direction that improves the efficiency as a function of the characteristic value of the internal combustion engine for adjusting the negative pressure with respect to the pressure reservoir in this operating state This is achieved by the control device.
[0007]
From German Offenlegungsschrift 19647092, an internal combustion engine control device is known in which similar problems are addressed. In this case as well, an operating state is described in which sufficient intake pipe negative pressure is not available for the operation of the brake force amplifier. In order to solve this problem, the engine is designed to be engaged with the internal combustion engine control so as to ensure a predetermined intake pipe negative pressure in the brake operation. When the brake is not operated, measures for securing the intake pipe pressure are not executed. However, not all possible applications are solved by this means, since sufficient negative pressure is required in the brake force amplifier reservoir for the operation of the brake force amplifier. The reason is that time is required to create a negative pressure in the reservoir.
[0008]
The method described below ensures the negative pressure in the brake force amplifier reservoir necessary for reliable operation of the brake force amplifier. Optionally required to evacuate the negative pressure reservoir when the negative pressure level in the brake force amplifier reservoir is reduced to such an extent that it is expected to adversely affect the operability of the brake force amplifier Engagement with the internal combustion engine control is performed.
[0009]
In this way, a sufficient negative pressure is ensured for the brake force amplifier in all applications immediately after the start of the internal combustion engine.
[0010]
It is particularly advantageous that a reduction in the efficiency of the internal combustion engine in certain operating conditions can be maintained even during braking, and that in particular the catalytic heating measures that are important for the operation of the internal combustion engine can be continued. . The disadvantageous effect of this reduction in efficiency for ensuring the negative pressure of the brake force amplifier occurs only when the negative pressure level in the pressure reservoir of the brake force amplifier is significantly reduced. This is generally the case when it occurs for the first time when the brake is operated multiple times during an operating condition that reduces efficiency. In this regard, it is advantageous that the reduced efficiency is recovered by the smallest possible filling amount and thus the largest possible intake pipe negative pressure in order to create the fastest negative pressure rise in the pressure reservoir.
[0011]
When the pressure level of the negative pressure reservoir is lowered, any other effects such as air conditioning compressor or steering assist pump and load increase due to altitude difference will also cause the vacuum pressure reservoir of the brake force amplifier to evacuate Is particularly advantageous.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.
[0013]
FIG. 1 shows a flowchart of internal combustion engine control. An example of such control is known from the above prior art as a torque-oriented control configuration. The control unit is denoted by reference numeral 10 in FIG. The control unit 10 is supplied with signals representing the operating variables of the internal combustion engine and / or the vehicle from the measuring devices 20-24 to 26 via various input lines 12-16 to 18, which are in the range of control of the internal combustion engine. Be evaluated within. Such operating variables are, for example, operating elements that can be operated by the driver, i.e., the position of the accelerator pedal, the engine rotational speed, the measurement variable that represents the amount of air supplied to the internal combustion engine, for example, the intake pipe pressure or the air supply mass depending on the embodiment A variable representing the flow rate, the position of the throttle valve of the internal combustion engine, the engine temperature, etc., and at least one engagement signal of another control device, such as a drive slip control device. In order to control the output of the internal combustion engine or the torque of the internal combustion engine, the control unit 10 adjusts at least fuel injection, ignition and air supply or cylinder filling by means of corresponding output signals. The output values controlling these operating variables are a function of the operating variables supplied via lines 12-16 to 18 in the control unit, in the preferred embodiment by the engine controller 30 known from the prior art described above. As determined. For the specific functions of the engine control device 30, reference is made to the prior art described at the beginning. In the normal case, the output signal is determined such that a predetermined torque is set, in which case the internal combustion engine operates as efficiently as possible. In certain operating situations, it is necessary to reduce this efficiency. Such operating conditions are, for example, the heating of the catalyst necessary after the start of the low-temperature internal combustion engine, the idling state in which the rapid torque increase engagement for idling control must be formed. For this purpose, as described in the prior art, the so-called torque margin value MDRES is calculated when the corresponding operating condition occurs, and this torque margin value MDRES is calculated based on the torque. 30 is taken into account when determining the output signal. The torque margin value MDRES increases the filling amount and simultaneously reduces the ignition angle, so that the torque of the internal combustion engine does not change with respect to the outside. In order to form the torque margin value MDRES, a torque margin forming stage 32 is provided in the flow chart of FIG. 1, and this torque margin forming stage 32 is provided for one corresponding operating state supplied via lines 34-36. A torque margin value is formed as a function of the signal representing the occurrence. These signals are measured by a measuring device, such as an idling switch, or are derived from measurements for detection of cold start and the need for catalyst heating, for example. The formation of these signals is symbolized by elements 38-40 in FIG.
[0014]
Increasing the charge reduces the negative pressure present in the intake pipe, which in some embodiments results in insufficient negative pressure in the negative pressure reservoir of the internal combustion engine used to supply the brake force amplifier. Despite performing a function that reduces efficiency, a simple model simulates the pressure in the pressure reservoir to ensure sufficient negative pressure in this reservoir, and is too low in the reservoir When the pressure is detected, the torque margin value MDRES is set to the fixed value MDRESBKV. In this case, the magnitude of the fixed torque margin value is determined so that the efficiency is improved again, the filling amount is reduced, and the negative pressure in the intake pipe is increased. The negative pressure reservoir is evacuated again. In this case, in a preferred embodiment, this value is determined in such a way that the internal combustion engine is operated with as little charge as possible. FIG. 1 shows a storage element 42 which contains a predetermined fixed value MDRESBKV for the torque margin. In addition, a signal forming stage 44 is provided which contains a model for the negative pressure in the reservoir, which signal forming stage 44 is provided with input signals supplied via couplings 46, 48 and 50 (described in more detail below in FIG. 2). The engagement signal is formed as a function of the switching element 52, which switches to a predetermined margin value and thus resets the efficiency drop (which is symbolized by a switching element 52 that switches the engagement signal from the position of the solid line to the position of the broken line). Is shown). When the signal forming stage 44 detects a situation in which it is assumed that the negative pressure in the pressure reservoir has decreased, the formed torque margin value MDRES is set to a fixed value from the storage element 42 by the corresponding control of the switching element 52. Set. This improves the efficiency so that an improved vacuum of the pressure reservoir is possible.
[0015]
The means executed for the switching decision will be described in detail with reference to the flow chart of FIG.
The measured intake pipe pressure Ps or the intake pipe pressure Ps calculated from the air mass flow signal measured via model formation is supplied to the signal formation stage 44 via line 46. In addition, a pressure signal representing the ambient pressure Pamb is supplied via line 48. Based on these two pressure signals, it is detected whether there is sufficient negative pressure in the reservoir. In this case, the pressure in the pressure reservoir is simulated by a simple model as described below.
[0016]
First, in the coupling stage 100, a deviation pds between the intake pipe pressure Ps and the ambient pressure Pamb is formed. The deviation pds is supplied to the other coupling stage 102, where the output signal PDS_IST of the integrator (constant KI) 104 is subtracted from the deviation dps. This integrator 104 indicates the pressure in the pressure reservoir. The difference dpds between the pressure deviation and the integrated state is weighted by the coefficient DPDS in the multiplication stage 106. The coefficient DPDS approximately represents the time constant of the pressure reservoir combined with the throttle position for pressure drop. The weighted value is used as an input signal to the integrator 104. The integrator output signal PDS_IST indicates the negative pressure in the pressure reservoir. This output signal PDS_IST is compared with the target value PDS_SOLL in the coupling stage 108. If the model pressure PDS_IST exceeds the target pressure by the hysteresis value DPHYS, no engagement signal is generated and the pressure difference is disconnected from the integrator input (switching element 110). In this case, there is sufficient pressure in the pressure reservoir, thus creating a normal torque margin. On the other hand, if the actual value is below the target value, an engagement signal is generated and the torque margin is switched to a smaller value MDRDSBKV, which may optionally be 0, so that an early ignition angle and a smaller filling amount Can set improved efficiency. This achieves a lower intake pipe pressure, and the pressure reservoir is again fully evacuated. At the same time, in such an operating situation, the integrator input is switched on again until the predetermined target pressure is again achieved. Another condition considered by the threshold switch 112 and the AND combination 114 is when the difference signal dpds is greater than zero, ie when the measured or calculated intake pipe pressure is below the model pressure in the pressure reservoir. Only the difference signal dpds is input to the entrance of the integrator 104. The reason is that the evacuation is performed only at this time. That is, the integrator 104 operates only when the measured or calculated intake pipe pressure is below the model pressure in the pressure reservoir and the actual pressure in the pressure reservoir is less than the target pressure. Otherwise, integrator 104 is stopped and holding its value.
[0017]
Instead of switching to a fixed torque margin when the pressure in the pressure reservoir is very small, a simple controller is used to reduce the torque margin until the actual pressure value approaches the target value again to reduce the torque margin. May be. In this case, the torque margin is changed as a function of the deviation between the actual value and the target value, where the change is zero when the actual pressure substantially corresponds to the target pressure.
[0018]
To improve the model, the pressure drop from the negative pressure reservoir may be simulated. The pressure drop is simulated by the following values being weighted by the model pressure present in the reservoir and subtracted from the integrator input signal. That is, in order to simulate a slight pressure loss due to non-tightness, a constant part DPVERL that works continuously is operated by the brake switch to simulate fluctuations in the brake pressure and the resulting pressure drop. A constant larger value that is subtracted as much as possible, and an even larger value that is subtracted only for a period of time after operating the brake switch to simulate the pressure drop that occurs when the brake is operated, A pressure drop is simulated by weighting with the model pressure present in the reservoir and subtracting from the integrator input signal. In order to take these values into account, the stop lamp switch state S_BL is supplied via line 50. If the state is equal to 1, that is, the brake pedal is being operated, this is detected in the comparison stage 116, the switching element 118 is closed, and the second value DPBRD is entered in the coupling stage 120. This signal is supplied to the other coupling stage 122 where the pressure loss value DPVERL is input. This signal is supplied to the weighting stage 124, which is further supplied with the model pressure PDS_IST. The weighted model pressure is then subtracted in the coupling stage 126 from the integrator input signal. Thereby, the pressure drop is taken into account. The coupling stage 120 is further supplied with another value DPBRT as described above, and this other value DPBRT is input when the stop lamp switch signal is at a positive flank and / or a negative flank. In the comparison stage 128, the flank of the stop lamp switch signal is detected and at this time the time counter 130 is started. The time counter 130 outputs a signal during time T, which inputs a predetermined value DPBRT into the coupling stage 120. When this time has elapsed after operating the brake switch, the weighting in the weighting stage 132 is adjusted so that the value DPBRT is no longer applied.
[0019]
The above model is simple, but in other embodiments it may be made finer. The value used is fixedly set and applied according to the use case. In the model, the integral of the deviation between the intake pipe pressure and the ambient pressure is below the threshold, and in some cases the operation of the brake switch is used to adjust the integral to adjust the efficiency Is a feature. The torque margin correction is executed only in the case of the catalyst heating function in some embodiments, and is also executed in the case of normal idling control in other embodiments. Instead of engaging the torque margin as described above, direct adjustment of the ignition angle or direct adjustment of the filling amount by shifting the ignition angle adjusted in the delay direction in the earlier direction is also conceivable. The adjustment of the ignition angle increases the negative pressure of the intake pipe, but in combination with the reduction of the filling amount, it works to keep the torque constant, and this measure works in the same way as the engagement with the torque margin itself.
[0020]
In some embodiments, additional measures are used that allow engagement in a direction that improves efficiency (eg, reduced torque margin) only under certain additional conditions. Such a condition is, for example, the passage of a certain time after engaging the idling range, which can prevent the engine from starting. Further, in some embodiments, measures are used to compensate for engagement to evacuate the pressure reservoir. An example for such a compensation measure is a gradual increase in the idle target rotational speed, which allows the air supply flow rate for the catalyst heating measure to be kept constant and nevertheless advance the ignition angle. The intake pipe pressure can be reduced so that the pressure reservoir is quickly evacuated.
[0021]
Instead of the pressure in the vacuum reservoir calculated via the model, the differential pressure measured via the differential pressure sensor between the pressure reservoir and ambient pressure may be used for the efficiency improvement engagement described above. Good.
[Brief description of the drawings]
FIG. 1 is a torque based engine control flow diagram in which means for ensuring negative pressure in a reservoir of a brake force amplifier is used, and is a flow diagram representing a microcomputer program of a control unit .
FIG. 2 is a flowchart showing determination of internal combustion engine control engagement for securing negative pressure, and is a flowchart showing a program of a microcomputer of a control unit.
[Explanation of symbols]
10 Control unit 20, 24, 26 Measuring device (operating variable)
30 Engine control unit 32 Torque margin forming stage 38, 40, 44 Signal forming stage 42 Storage element 52, 110, 118 Switching element 100, 102, 108, 120, 122, 126 Coupling stage 104 Integrator 106, 124 Multiplication stage 112 Threshold switch 114 AND combination 116, 128 Comparison stage 124, 132 Weighting stage 130 Time counter

Claims (11)

A normal operation state and an operation state in which the efficiency is lower than that of the normal operation state. In the control method of the internal combustion engine, which is one of a high operating state and an operating state in which the ignition angle is delayed from the normal operation,
Also der when in the operating condition the internal combustion engine is the efficiency is decreased, when the negative pressure in the pressure reservoir of the braking amplifier is smaller than a predetermined target value, the step of reducing the torque margin value, the filling A control method for an internal combustion engine, wherein the efficiency of the internal combustion engine is increased by any one of a step of reducing the amount and a step of advancing the ignition angle to increase the intake pipe negative pressure.  The method of claim 1, wherein the increase in efficiency is a function of a deviation between intake pipe pressure and ambient pressure.  3. The method according to claim 2, wherein the deviation of the intake pipe pressure from the ambient pressure or the value derived therefrom is integrated and compared with the target value.  The efficiency of the internal combustion engine is a function of the deviation between the intake pipe pressure and the ambient pressure, in particular as a function of the integral of this deviation, so that the pressure reservoir of the brake force amplifier is evacuated by reducing the filling amount and increasing the intake pipe negative pressure. 4. A method according to claim 2 or 3, characterized in that the method is improved.  4. The method according to claim 3, wherein the integration result is corrected as a function of the brake pedal switch signal.  4. A method according to claim 3, characterized in that the integration result corresponds to the pressure in the pressure reservoir and that the efficiency is increased when this pressure is very low.  7. The method according to claim 1, wherein the efficiency improvement is performed by a closed loop control circuit so that the desired pressure is set as rapidly as possible.  8. A method according to any one of the preceding claims, characterized in that the target idle speed is increased in improving efficiency.  9. The method according to claim 1, wherein the efficiency improvement is performed only after a predetermined time has elapsed since the start of the idle operation.  Instead of the pressure in the pressure reservoir calculated from the characteristic value by the model, the differential pressure between the pressure reservoir measured by the differential pressure sensor and the ambient pressure is used to improve the efficiency. 10. The method according to any one of claims 1 to 9. Provided with a control unit that operates the internal combustion engine in an operation state in which the efficiency is lower than that in the normal operation state. In the control device for an internal combustion engine, which is an operation state in which the amount of operation is high, or an operation state in which the ignition angle is delayed from normal operation,
Wherein the control unit I also der when in the operating condition in which the efficiency is decreased, when the negative pressure in the pressure reservoir of the braking amplifier is smaller than a predetermined target value, the step of reducing the torque margin value, An internal combustion engine comprising means for increasing the efficiency of the internal combustion engine and increasing the intake pipe negative pressure by any one of the step of reducing the filling amount and the step of advancing the ignition angle. Control device.

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