EP0768456A2 - Method and apparatus for controlling an internal combustion engine - Google Patents

Abstract

The control system provides a signal representing the required power output of the engine in dependence on monitored operating parameters, with the power output signal, for metering the fuel supplied to the engine, raised during moving off after a defined waiting time, which is pref. dependent on the engine revs. Pref. the moving off condition is detected when the brake is not applied and the vehicle velocity signal and accelerator pedal position signal reach given values, with limitation of the amount by which the powder output requirement is increased.

Description

State of the art

The invention relates to a method and a device for controlling an internal combustion engine.

DE-OS 24 40 013 discloses a method and devices for controlling an internal combustion engine. In these methods and devices for controlling the internal combustion engine, the amount to be injected is increased by a temperature-dependent value when starting after a waiting time has elapsed, which value is then continuously reduced over time.

In the case of such methods and devices for controlling an internal combustion engine, the case may arise that the engine speed increases only very slowly or not far enough when the vehicle is started up. This means that the dynamics of the vehicle or the acceleration behavior of the vehicle is very poor and, in the worst case, leads to staying on the mountain.

This starting weakness occurs in particular when the starting process takes place with an increased load, for example when the vehicle is on an incline, or when the the fuel used is of poor quality, or there are other unfavorable thermal or atmospheric conditions.

Object of the invention

The invention has for its object to achieve a rapid increase in speed in a method and a device for controlling an internal combustion engine under all boundary conditions when starting. This object is achieved by the features characterized in the independent claims.

Advantages of the invention

With the procedure according to the invention, a sufficiently rapid speed increase can be ensured even under unfavorable boundary conditions when starting off.

Advantageous and expedient refinements and developments of the invention are characterized in the subclaims.

drawing

The invention is explained below with reference to the embodiments shown in the drawing. FIG. 1 shows a block diagram of the device according to the invention and FIG. 2 shows a flow diagram of the method according to the invention.

Description of the embodiments

The procedure according to the invention is described below using the example of a diesel internal combustion engine.

100 designates a power-determining actuator. A diesel internal combustion engine is the control rod of an in-line pump or the adjustment lever of a distributor pump. Solenoid valve controlled systems are solenoid valves that determine the fuel metering. In the case of spark-ignited internal combustion engines, the actuator 100 is a steeper for changing the throttle valve position.

The output signal of a node 105 is fed to this power-determining actuator 100 as a power-determining signal. The node processes the output signal MEA of a start-up quantity map 110 and the output signal MER of a multi-quantity ramp 115.

The output signal of a switching means 120 and the output signal of a connection point 125 are fed to the multi-quantity ramp 115.

The node 125 forms the difference between the output signal MEM of a map 130, in which the maximum permissible starting quantity is stored, and the signal MEB of a limiting map 135. The map 130 is supplied with a speed signal N, among other things.

In the idle position, the switching means 120 connects the minimum quantity specification 140 to the quantity ramp 115. When the switching means 120 is activated, this connects a connection point 145 to the quantity ramp 115. The connection point 145 links the output signal MEP of the quantity specification with the negative sign of the output signal ME (dN / dt) of the negative feedback 150. The negative feedback 150 is supplied with the speed signal N, among other things.

The switching means 120 is driven by the output of an AND gate 155. The AND gate combines the output signal ANF of a second AND gate 160 and the output signal of a holding element 165. The AND gate 160 receives the output signal of the node 125 and a speed condition of a block 161, a condition for the pedal value transmitter of block 162 and a signal fed to the brake 163.

The holding element 165 is acted on by a delay 170 with a signal. The delay element in turn is acted upon by a switching means 175. The switching means processes the output signal VT of a node 180 at whose one input with a positive sign the output signal VT0 of a delay time specification 185 is present and at the second output with a negative sign the output signal F (dN / dt) of a delay correction 190 is present. Delay correction 190 is used, among other things. the speed signal supplied.

The quantity ramp 115 acts on the holding member 165 and the switching means 125 with control signals. The AND gate 160 accordingly applies a control signal to the switching means 175.

The mode of operation of this device is described below with reference to the flow chart according to FIG. 2. The initialization takes place in a first step 200. The excess quantity MER of the quantity ramp 115 and the delay time VT are set to 0. A final value VTO for the delay time is specified by the delay time specification 185. Subsequently, query 210 checks whether a starting condition ANF is present. If this is not the case, step 200 follows again. If this is the case, then in Step 220 increases the delay time VT by a fixed value.

The query 230 checks whether the value of the delay time VT is less than or equal to a final value VT0. If this is not the case, the delay time is shortened by a correction value F in step 240. This correction value F (dN / dt) depends on the change in speed, in particular on the speed increase. The correction value is specified by the delay time correction 190. When the speed increases, the delay time VT is shortened. This means that a positive value is subtracted. The delay time corrected by the correction value F (dN / dt) is then present at the output of the node 180.

If query 230 recognizes that the delay time is greater than or equal to the end value VTO, that is to say that the delay time VT has expired and a time condition has been met, step 250 follows. This means that the output signal of the delay 170 assumes a high signal level which is from Holding member 165 is maintained until the quantity ramp 115 emits a corresponding reset signal.

In step 250, the value of the additional quantity MER is increased by a positive value MEP, which is specified by the additional quantity specification 145. Then in step 260, the excess quantity MER is reduced by a correction value ME (dN / dt), which is provided by the negative feedback 150 and is dependent on the change in the speed, in particular the speed increase.

The increase in the excess quantity MER takes place only when the delay time VT has expired and the starting condition ANF is present. In this case, the AND gate 155 controls this Switching means 120 and the output signal of node 145 reach mass ramp 115.

In the quantity ramp 115, the excess quantity MER is limited to the value MEG, the limit value for the excess quantity. This means that a query 270 follows after step 260, which checks whether the additional quantity MER is greater than or equal to the limit value MEG. If this is the case, the excess quantity is set to the limit value MEG in step 275.

A query 280 then follows, which checks whether the starting condition ANF is still present. If this is the case, step 250 takes place again. If the starting condition is no longer present, ie the signal AMF is no longer present, the switching means 120 changes to its rest position. This means that in step 285 the excess quantity MER is reduced by the value MEN of the minimum quantity specification 140.
The query 290 then checks whether the additional quantity MER is less than or equal to zero. If this is not the case, query 280 is repeated. If this is the case, step 200 is carried out. This means that as soon as the excess quantity becomes less than or equal to zero, the delay time is reset to its initial value and the holding element 165 is reset to zero .

If query 280 recognizes that the starting condition ANF is present, the quantity is increased further until the limit value MEG is reached. If query 280 recognizes that the start-up condition is no longer present, the quantity is reduced by the value MEN. As soon as the starting condition is present again, the quantity is increased again by the value MEP.

According to the invention, when the start-up condition is met, the additional quantity (MER) increases over time until the limit value MEG is reached. If the starting condition no longer applies, the Excess quantity over time until the quantity has returned to its original value before the increase.

Query 210 or query 280 check whether the starting condition is present; these queries are shown in more detail in sub-figure 2b. This query corresponds to the AND gate 160.

A first query 211 checks whether an accelerator pedal position signal PWG is greater than a threshold value SP. If this is not the case, the start-up condition is not recognized. This condition checks whether the accelerator pedal is depressed.

If this is the case, query 212 checks whether a vehicle speed signal V is less than a threshold value SV. If the driving speed signal V is greater than the threshold value, it is recognized that the starting condition is not present.

If the vehicle speed signal V is greater than the threshold value, query 213 checks whether the brake of the vehicle is not actuated. If the brake is actuated, the starting condition is not recognized. For this purpose, the position of a brake light switch is evaluated, for example.

If the brake is not actuated, query 214 follows, which checks whether the output signal MEM of the characteristic map 130 is greater than the output signal MED of the limiting characteristic map 135. If this is not the case, the starting condition is not present. If this is the case, the start-up condition is recognized.

The presence of the start-up case is only recognized when the accelerator pedal value PWG is greater than a threshold value SP, the speed is less than a threshold value SV, the output signal of the limiting map 135 is less than the maximum possible starting quantity MEM and the brake is not actuated. In the case of embodiments of the inventions, further conditions can be added or conditions can be omitted. After a recognized starting request, a delay time VT is waited for and the starting quantity is then increased in a ramp.

So that the delay time VT can be applied briefly and still does not run too quickly during normal starting, this delay time is dynamically extended as a function of the speed increase. For this purpose, a delay time VT0 is specified, which is then shortened by a value that depends on the speed increase. In the case of a strong increase in the speed, the delay time VT is shortened by a small amount and in the case of a small increase by a large amount. This means that the waiting time is very long if the speed increases rapidly and very short if the speed increases slowly.

If the start-up condition does not apply, i.e. that one of the conditions no longer exists, already during the delay time VT, the delay time is immediately reset to its initial value.

If the delay time has expired and the starting condition is still present, the additional quantity MER is increased by a predetermined value. The additional quantity MER is limited to a value MEG, which corresponds to the difference between the maximum permitted additional quantity and the output signal MEB of the limiting characteristic diagram 135.

If the start-up condition does not apply during the ascent ramp, the quantity ramp is reduced with the negative slope MEN. If a starting condition is recognized again, it is immediately increased again with a positive gradient MEP. If the excess quantity reaches zero again, the delay time is reset. The quantity will only increase again when the delay time has expired.

In order that the quantity increase required for increasing the speed does not always increase up to the maximum permissible increase value, a speed increase feedback 150 is provided. The current volume ramp value is reduced in accordance with the current speed increase by a correction quantity ME, which depends on the speed increase.

Claims (8)

Method for controlling an internal combustion engine, in particular a self-igniting internal combustion engine, whereby a performance-determining signal can be specified depending on various operating parameters, the performance-determining signal being increased after a waiting time if a starting condition is present, characterized in that, when the starting condition is present, the performance-determining signal is above the Time increases and the performance-determining signal decreases over time if the start-up condition no longer applies. The method of claim 1, that the waiting time depends on the change in speed. Method according to one of claims 1 or 2, characterized in that the starting condition is recognized when a brake is not actuated, a driving speed signal and an accelerator pedal position signal assume certain values. Method according to one of the preceding claims, characterized in that the value by which the power-determining signal increases is reduced by a value which depends on the signal which corresponds to the change in the speed. Method according to one of the preceding claims, characterized in that the power-determining signal is the amount of fuel to be injected. Method according to one of the preceding claims, characterized in that the value by which the power-determining signal is increased is limited to a limit value. Method according to one of the preceding claims, characterized in that the power-determining signal is reduced until it has reached the value which existed before the increase. Device for controlling an internal combustion engine, in particular a self-igniting internal combustion engine, whereby a power-determining signal can be specified as a function of various operating parameters, the power-determining signal being increased after a waiting time if a starting condition is present, characterized in that means are provided which are present when the starting condition is present increase the power-determining signal over time and reduce the power-determining signal over time if the start-up condition no longer applies.

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