JP2518203B2 - Engine controller - Google Patents

Description

The present invention relates to an engine control device having an idle speed control function and a fuel cut function, such as an electronically controlled fuel injection device.

[Prior Art] The rotational speed of a vehicle engine during idling is basically controlled to an optimum value according to the characteristics of the engine, that is, a basic target idle rotational speed. This basic target idle speed is normally set to the lowest possible value at the time of shipment of the vehicle from the viewpoint of reducing fuel consumption unless irregular vibration of the engine occurs, but after that, changes in the operating environment, aging of the engine, etc. According to the above, it can be changed when adjusting the engine (Japanese Patent Laid-Open No. 59-136540).

The engine control device adjusts the idle speed by the opening of the intake air valve for idle speed control (ISCV) and the like with the above-mentioned basic target idle speed as a target during normal idle. Alternatively, depending on operating conditions such as when the air conditioner is switched on and the engine load increases, a separate ISCV
The idle rotation speed may be increased by increasing the opening degree of.

On the other hand, some engine control devices have a fuel cut function. This is a function of stopping the fuel supply to the engine for the purpose of improving fuel efficiency and braking effect when the vehicle is decelerated by the engine brake. It operates when conditions such as the valve being fully closed are satisfied.

[Problems to be Solved by the Invention] As described above, the engine idle rotation speed may be higher than the basic target idle rotation speed depending on operating conditions. At this time, the increased rotation speed is
The value approaches the value of the predetermined rotation speed, which is one of the criteria for determining whether to execute fuel cut. When adjusting the vehicle at the time of shipping, the basic target idle rotation speed and the fuel cut reference rotation speed are set to values sufficiently separated from each other, and even when the ISCV opening is increased due to operating conditions, etc. As a result, the increased rotation speed is prevented from exceeding the fuel cut reference rotation speed.

However, if the basic target idle speed is changed to a high value in response to changes in the operating environment, engine aging, etc., the idle speed will be fuel cut when the ISCV opening is increased according to operating conditions. It may exceed the reference speed. In such a case, there arises a problem that the engine is stopped at the time of idling.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and provide an engine control device capable of freely adjusting when changing the idle rotation speed without considering the relationship with the fuel cut rotation speed.

[Means for Solving the Problems] In order to solve the above problems, the means taken by the present invention is, as shown in FIG. 1, an operating state detecting means for detecting an operating state of a vehicle engine, and Based on the operating state detected by the operating state detecting means, a fuel cut rotational speed setting means for setting and storing a fuel cut rotational speed for stopping fuel supply to the engine, and a reference value of a target idle rotational speed of the engine. Based on the command value of the external operation means, based on the command value of the external operation means, the external operation means for outputting a predetermined command value by an external operation when changing the reference value. Correction value storage means for storing a correction value for changing the reference value of, and the target idle rotation speed stored in the reference value storage means are stored in the correction value storage means. Target idle rotation speed changing means for changing according to a correction value, idle rotation speed control means for controlling the idle rotation speed of the engine to the target idle rotation speed changed by the target idle rotation speed changing means, and the fuel cut rotation The fuel cut rotation speed stored in the speed setting means, the fuel cut rotation speed correction means for adding the change amount of the target idle rotation speed changed by the target idle rotation speed changing means, and the rotation speed of the engine, An engine control device comprising: a fuel cut control means for stopping the fuel supply to the engine when the fuel cut rotation speed corrected by the fuel cut rotation speed correction means is equal to or higher than the fuel cut rotation speed. To do.

[Operation] In the engine control device of the present invention, when the engine rotation speed becomes equal to or higher than the predetermined fuel cut rotation speed, the fuel cut control is performed to stop the fuel supply to the engine, and the idle rotation speed is set to the target idle speed. Idle rotation speed control for controlling the rotation speed is performed. Further, for example, at the time of factory shipment, the reference value of the target idle rotation speed is stored in advance, and the correction value (of the target idle rotation speed) set to an arbitrary value by the ISC controller or the like is stored. To change the reference value. When the reference value is changed by this correction value, the changed amount of the changed target idle rotation speed is added to the fuel cut rotation speed for correction. Therefore, the difference between the target idle rotation speed and the fuel cut rotation speed is always maintained at a constant suitable value, and the fuel cut rotation speed does not increase excessively.

[Example] One of the examples of the present invention will be described below. FIG. 2 shows an exemplary configuration of an engine control system including an engine control device according to the present invention.

In FIG. 2, the intake manifold 2 of the engine 1 is provided with a bypass passage 6 which is an air passage bypassing the throttle valve 4, and the bypass passage 6 has an idle speed control valve (ISCV) for controlling the opening area thereof.
8 are provided. As an air passage that bypasses the throttle valve 4 of the intake manifold 2, a first idle bypass passage 10 is provided in addition to the air valve.
12 controls the amount of air flowing through it. The intake air is taken into the intake manifold 2 from the air cleaner 14, and the flow rate thereof is detected by the air flow meter 16. A fuel injection valve 18 is provided near the engine body 1 of the intake manifold 2 and injects fuel into intake air according to a command from an electronic control circuit (ECU) 20.

The ECU 20 has an air flow rate signal from the air flow meter 16, an engine rotation speed signal from a rotation angle sensor 24 in the distributor 22, a water temperature sensor 26 for detecting the cooling water temperature of the engine 1, and an opening degree of the throttle valve 4. Throttle position sensor 28, key switch 3
Signals from 0, the battery 32, the air conditioner switch 34, etc. are taken in. Further, the ISC adjuster 36 and the T terminal 38 for adjusting the basic target idle speed of the engine 1 are also connected to the ECU 20.
It is connected to the.

An example of the configuration of the ISC adjuster 36 is shown in FIG. 3. In this case, the ECU 20 is changed by changing the resistance value of the variable resistor 37.
The electric potential input to is changed, and the ECU 20 changes the basic target idle rotation speed according to the input value. The changing operation is performed only when the ECU 20 senses that the T terminal 38 is in the ON state.

 The structure of the ECU 20 is shown in FIG.

Reference numeral 40 denotes a central processing unit (hereinafter simply referred to as CPU) that performs processing for inputting and calculating data output from each sensor according to a control program and controlling operation of various devices such as ISCV8, and 41 denotes the control program. And a read only memory (hereinafter simply referred to as ROM) in which initial data is stored, 42 is a random access memory (hereinafter simply referred to as RAM) in which data input to the ECU 20 and data necessary for arithmetic control are read and written, and 43 is A backup random access memory (hereinafter simply referred to as backup RAM) backed up by a battery so as to retain data necessary for engine operation even when the key switch 30 is turned off, 44 is an input port (not shown), and is required. Corresponding waveform shaping circuit, the output signal of each sensor is selectively output to CPU40 Mux,
Each of the input units is provided with an A / D converter for converting an analog signal into a digital signal. Reference numeral 45 is an output section which is provided with an output port (not shown) and a drive circuit which drives the ISC V8 or the like according to the control signal of the CPU 40, and 46 is a CP
Each of the elements such as U40 and ROM 41 and the input section 44 and the output section 45 are connected to represent a bus line to which each data is sent.

Of the control program executed by the ECU 20, the processing by the subroutine according to the present invention will be described below based on the flowchart shown in FIG. In this subroutine, the crank angle of the engine 1 (representing the angle from the top dead center before the intake cycle of the first cylinder, expressed as ° CA) is 180 ° CA.
Each time, the main control program executes an interrupt. Before entering this subroutine, predetermined processing is executed and signals from the above sensors are input,
It is stored in RAM42.

When this routine is entered, first, at step 100, the fuel cut rotation speed NCUT is calculated based on the cooling water temperature of the engine 1 which is already input and is stored in the RAM 42. Next step 110
At, it is determined whether the conditions for performing the idle target rotation speed control (ISC control) are satisfied. The engine 1 is not being started by the starter, the throttle valve 4 is fully closed (IDL ON), and the engine 1 cooling water temperature is 70.
If the conditions for performing the ISC control that the temperature is equal to or higher than 0 ° C and the vehicle is not running, the process proceeds to step 12
Go to 0. Here, the I
The opening of SCV8 is determined and assigned to the variable ISCON. For example, when the engine 1 is starting by the starter, IS
The opening of CV8 is 100%, etc. And step 130
At, 0 is substituted into a variable ΔNF described later.

If the condition to perform ISC is satisfied, the process is step 1
The program proceeds to 40, where the initial value (NF) of the basic target idle rotation speed is read from the ROM 41. Next, at step 150, the basic target idle rotation speed correction value ΔNF is calculated from the adjustment value AJISC of the ISC adjuster 36. The method of calculating this ΔNF will be described below.

FIG. 6 shows a flowchart of a subroutine that is executed when the basic target idle rotation speed is changed by using the ISC adjuster 36 shown in FIG. This subroutine is processed by interruption at regular intervals from the main routine. When it starts, it is first checked in step 300 whether the T terminal 38 is turned on. If not, what processing is done in this subroutine. Return to the main routine without being done. T terminal 38
Only when is on, go to step 310 and
Input the analog potential AJISC, which is the output value of, and convert the analog signal into 8-bit digital signal IDX in the next step 320, and backup the IDX in step 330.
Remember in 43.

Returning to FIG. 5, in step 150, ΔNF is determined from the value of only the upper 3 bits of this 8-bit IDX by the lookup table shown in Table 1. In Table 1, * represents an arbitrary value of 0 or 1.

After ΔNF is determined in step 150, the correction value ΔNF is added to the initial value NF to determine a new basic target idle rotation speed NF in step 160. Next, at step 170, the opening ISC of ISC V8 corresponding to the rotation speed from the new NF
ON is decided. Here, it is determined by so-called learning control based on the actual rotational speed NE of the engine 1 already input and stored in the RAM 42 and the target value NF.

Predetermined ISCON determined when the conditions for ISC control are not met, or ISCO determined under the above ISC
The opening of ISC V8 is decided by N, but next step
At 180, it is determined whether the idle-up condition is met. For example, when it is determined that the idle-up condition is satisfied, such as when the charging potential of the battery 32 becomes lower than a predetermined value or when the air conditioner switch 34 is turned on, the process proceeds to step 190 and the idle-up condition is met. A correction value ISUP of the ISCV opening is calculated. Then, in step 200, the correction value ISUP is added to ISCON to determine a new ISCON, and then the process proceeds to step 210. Step
If it is determined in 180 that the idle-up condition does not exist, the value of ISCON is not changed and the step 2
Go to 10.

In step 210, a new NCUT is determined by adding the corrected rotational speed value ΔNF determined in step 130 or step 150 to the fuel cut rotational speed NCUT calculated in step 100.

The step 210 of this flowchart can be replaced with the process shown in FIG. That is, in step 212, it is judged whether the difference between the fuel cut rotation speed NCUT and the basic target idle rotation speed NF is 300 rpm or less, and only when the result is YES, NCUT + ΔNF is set as a new NCUT as in step 210 described above. To do.

After the opening ISCON of the ISC V8 and the fuel cut rotation speed NCUT are determined by the above subroutine, the process returns to the main program of the engine control, and the overall control of the engine including the idle control and the fuel cut control is performed.

In this embodiment, the idle control unit M1 shown in FIG.
U20 and part of the program executed in it, and I
Equivalent to SC adjuster 36 and T terminal 38, fuel cut control unit M2
Corresponds to the ECU 20 and a part of the program executed therein, and the engine control unit M3 corresponds to the program executed in the ECU 20 and the ECU 20 including the subroutine of FIG.

According to this embodiment, the fuel cut rotation speed is changed by the same amount as the change amount of the basic target idle rotation speed.
Even when the idle rotation speed is increased due to conditions such as a decrease in battery charge potential and the air conditioner switch being turned on, the increased idle rotation speed must not exceed the fuel cut rotation speed as when initially set. become. Therefore, the basic target idle speed can be freely set to ISC without consideration for stopping the engine at idle.
It can be adjusted by the adjuster 36. Further, in the present embodiment, even when the target idle rotation speed is increased, the degree of increase in the fuel cut rotation speed is limited to the amount of change in the target idle rotation speed, so carelessly at an undesired time. Fuel cut will not be executed,
It does not hinder the running of the vehicle.

In the above embodiment, regardless of whether the correction value ΔNF is positive or negative, the fuel cut rotational speed NCUT is Δ
NF was added, but these steps 210 and 214
The part may be replaced with a flowchart as shown in FIG. That is, in step 216, it is determined whether or not ΔNF is a positive value, and only when it is a positive value, in step 218 ΔNF is determined.
Is added to NCUT and the basic target idle speed NF is lowered, the fuel cut speed NCUT is not changed.

In the above embodiment, the correction value ΔNF is set by the ISC adjuster 36.
However, if the ECU 20 has an engine diagnosis function, for example, ΔNF may be determined by a table or map in the ROM 41 according to the result.

[Advantages of the Invention] In the engine control device of the present invention, when the reference value of the target idle rotation speed is changed by the correction value of the target idle rotation speed, the fuel is changed by the changed target idle rotation speed. Since the cut rotation speed is corrected, the difference between the target idle rotation speed and the fuel cut rotation speed is always held at a constant and suitable value. Therefore, the target idle rotation speed does not exceed the fuel cut rotation speed, and it is possible to avoid a situation where the engine is stopped during idling.

Further, in the present invention, when the target idle rotation speed is increased, the degree of increase in the fuel cut rotation speed is limited to the amount by which the target idle rotation speed is changed. Is not executed, and it does not hinder normal engine control or running of the vehicle.

Further, in the present invention, when adjusting the idle rotation speed, the target idle rotation speed can be freely adjusted without considering the relationship with the fuel cut rotation speed, so workability is greatly improved. To do.

[Brief description of drawings]

FIG. 1 is an explanatory diagram for explaining the basic concept of the present invention, FIG. 2 is a configuration diagram of an embodiment of the present invention, FIG. 3 is a circuit diagram showing an example of an ISC regulator, and FIG. 4 is a block of an ECU. FIG. 5 is a flowchart of a subroutine according to the embodiment, FIG. 6 is a flowchart for changing the basic target idle rotation speed, FIG. 7 is a flowchart for replacing a part of the subroutine of FIG. 5, and FIG. Is a flowchart for replacing a part of the flowcharts of FIGS. 5 and 7. 1 …… Engine 8 …… Idle speed control valve (ISCV) 20 …… Electronic control circuit (ECU) 24 …… Rotation angle sensor 36 …… ISC adjuster 38 …… T terminal

Claims (1)

(57) [Claims] 1. A driving state detecting means for detecting a driving state of a vehicle engine, and a driving state detected by the driving state detecting means,
Fuel cut rotation speed setting means for setting and storing a fuel cut rotation speed for stopping fuel supply to the engine; reference value storage means for previously storing a reference value of the target idle rotation speed of the engine; and the reference value. An external operation means for outputting a predetermined command value by an external operation when changing the value, and a correction value for changing the reference value of the target idle rotation speed based on the command value of the external operation means. Correction value storage means, target idle rotation speed changing means for changing the target idle rotation speed stored in the reference value storage means according to the correction value stored in the correction value storage means, and idle rotation speed of the engine. An idle rotation speed control means for controlling the target idle rotation speed changed by the target idle rotation speed changing means; Fuel cut rotation speed correction means for adding the fuel cut rotation speed stored by the engine rotation speed setting means by the change amount of the target idle rotation speed changed by the target idle rotation speed changing means, and the rotation of the engine. A fuel cut control means for stopping the fuel supply to the engine when the speed becomes equal to or higher than the fuel cut rotation speed corrected by the fuel cut rotation speed correction means. apparatus.