JPH0612234Y2 - Electronic control unit for diesel engine - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a main intake throttle valve provided in a main intake passage and a sub intake bypassing the main intake throttle valve for the intake opening area of a diesel engine. The present invention relates to a diesel engine electronic control unit that is controlled by an intake throttle valve.

[Prior Art] In an electronic control device for a diesel engine, which adjusts an intake opening area of a diesel engine with a main intake throttle valve provided in a main intake passage and a sub intake throttle valve provided in a sub intake passage, for example, As disclosed in Japanese Patent Laid-Open No. 59-5845, "Method of controlling intake throttle of diesel engine", the main intake throttle valve is closed during idle operation, and the auxiliary intake throttle valve is set to an intermediate opening degree, so that the engine is idle. During the deceleration operation other than the above, the main intake throttle valve is closed and the sub intake throttle valve is fully opened to be fully opened.

"Problems to be solved by the device" The electronic control unit of the diesel engine as shown in the above "method for controlling the intake throttle of the diesel engine" throttles the opening area of the intake during idle operation to reduce engine vibration and noise. On the other hand, while having the excellent effect of preventing the generation of white smoke due to insufficient intake air without excessively narrowing the opening area of intake air during deceleration operation, the following problems have been considered.

That is, in recent years, in an electronic control device for a diesel engine equipped with an electronic fuel injection control device, when the diesel engine rotates at a deceleration speed equal to or higher than a predetermined rotational speed (hereinafter, simply referred to as fuel cut), the fuel Although the injection amount is cut to improve the operating efficiency of the diesel engine, at the time of this fuel cut, white smoke is not generated due to lack of intake air because fuel injection is not performed. Therefore, even during deceleration operation, it is not only unnecessary control to release the auxiliary intake throttle valve while the fuel cut is being executed, but also the opening area increases due to the release of the auxiliary intake throttle valve. Problems such as generation of vibration and noise (so-called muffled sound) have been considered.

The electronic control unit for a diesel engine of the present invention has been made in view of the above problems, and its purpose is to prevent generation of white smoke during deceleration operation and to reduce muffled noise.

Configuration of the Invention [Means for Solving the Problems] The electronic control unit for a diesel engine of the present invention is provided with an intake opening area of the diesel engine in the main intake passage, as shown in the basic configuration of FIG. The main intake throttle valve and the auxiliary intake throttle valve provided in the auxiliary intake passage that bypasses the main intake throttle valve are adjusted to open the main intake throttle valve during deceleration of the diesel engine to open the auxiliary intake throttle valve. Intake throttle control means (M1) for fully opening the valve
And a fuel cut control means (M2) for performing a fuel cut when the diesel engine is decelerating and when the rotation speed of the diesel engine is equal to or higher than a predetermined rotation speed. The intake throttle control means (M1) is provided with a compensating means (M3) that throttles the auxiliary intake throttle valve when the fuel cut control means (M2) is performing fuel cut. .

Here, when decelerating the diesel engine, the load of the diesel engine is a predetermined value or less, for example, the intake pipe pressure that reflects the load of the diesel engine is a predetermined value or less, the state is intake It can be considered that the pressure is detected by a vacuum sensor that detects the pipe pressure.

[Operation] The electronic control unit of the diesel engine of the present invention having the above-described structure operates as follows.

The electronic control unit of the diesel engine of the present invention is an intake throttle control means (M1) at the time of deceleration of the diesel engine.
Closes the main intake throttle valve and fully opens the auxiliary intake throttle valve to prevent the generation of white smoke during deceleration, and at the time of deceleration and when the rotation speed of the diesel engine is equal to or higher than a predetermined rotation speed. When the fuel cut control means (M2) cuts the fuel, the compensating means (M3) provided in the intake throttle control means (M1) works to throttle the auxiliary intake throttle valve in the fully open state. As a result, the electronic control unit of the diesel engine of the present invention works to reduce the muffled noise by narrowing the opening area of the intake air at the time of fuel cut that does not generate white smoke even during deceleration.

[Embodiment] Next, a preferred embodiment will be described with reference to the drawings in order to further clarify the configuration of the electronic control unit for a diesel engine of the present invention.

FIG. 2 is a schematic configuration diagram showing an engine peripheral portion of a vehicle equipped with an electronic control unit for a diesel engine according to an embodiment of the present invention.

As shown in the figure, in the intake pipe 2 of the 4-cylinder diesel engine 1, from the upstream side, a main intake throttle valve 3 and an auxiliary intake throttle valve 4 that adjust the intake opening area of the intake pipe 2, a vacuum that detects the intake pipe pressure. The sensor 5, etc. are provided. The main intake throttle valve 3 has its opening increased as the depression amount of the accelerator pedal 6 depressed by the driver increases, and adjusts the opening area of the main intake passage 7. The auxiliary intake throttle valve 4 is
The opening of the diaphragm device (described in detail later) 8 is changed to adjust the opening area of the auxiliary intake passage 9. The intake pipe 2 is also provided with a so-called EGR valve 15. As is well known, the EGR valve 15 is provided for the intake pipe 2
The vacuum pump 1 as a negative pressure generating source is for adjusting the opening area of the pipe line 17 that connects the exhaust pipe 16 with the exhaust pipe 16.
8 is operated according to the operation of the electric negative pressure regulating valve 19 supplied with the negative pressure by 8. Further, on the upstream side of the intake pipe 2, an exhaust turbine supercharger (turbocharger) 20 for supplying high-density intake air to the engine 1 by utilizing the exhaust gas of the exhaust pipe 16 is also provided.

On the other hand, a fuel injection valve (not shown) provided in each cylinder of the engine 1 is supplied with a fuel injection amount according to the rotation of an accelerator lever 25 which is interlocked with an accelerator pedal 6 depressed by a driver, by an injection pump 26. To be done. The injection pump 26 is also provided with a rotation speed sensor 27 and the like that detects the engine rotation speed in conjunction with a crank shaft (not shown).

The diaphragm device 8 includes two diaphragm chambers 8
The opening degree of the auxiliary intake throttle valve 4 depends on the on / off state of the vacuum switching valves (hereinafter simply referred to as VSV) 30 and 31 that have A and 8B and serve to supply negative pressure to the respective diaphragm chambers 8A and 8B. Is configured to adjust. That is, when both VSVs 30 and 31 are turned on, the auxiliary intake throttle valve 4 is fully closed, when either one is turned on, it is half-opened, and when both are turned off, it is fully opened. The VSV 31 is normally kept in the off state when the vehicle is operating. Therefore, when the vehicle is operating, the auxiliary intake throttle valve 4 is opened halfway or fully. Further, a negative pressure is supplied to the VSVs 31 and 31 via the pipes 32 and 33 by the vacuum pump 18 described above.

The vacuum sensor 5, the accelerator lever 25, the rotation speed sensor 27, the water temperature sensor 34 for detecting the temperature of the cooling water of the engine 1, and the like are external input circuits of an electronic control unit (hereinafter referred to as ECU) 35 shown in FIG. 35d connected to the electric negative pressure regulating valve 19, VSV 30 and 31
Is connected to the external output circuit 35e of the ECU 35.

The ECU 35 is configured as a logical operation circuit centering on a well-known CPU 35a, ROM 35b, RAM 35c, etc., and these external input circuit 35d, external output circuit 35e, etc., connected to each other by a bus 35f.

Next, among various processes performed by the ECU 35,
The "intake throttle control routine" that is executed when the driver fully decelerates the main intake throttle valve 3 that is linked to the accelerator pedal 6 and decelerates the intake pipe pressure PM detected by the vacuum sensor 5 to a predetermined value or less will be described. .

The "intake throttle control routine" shown in FIG. 4 is regularly executed by a method such as a hard interrupt during deceleration.

When the processing shifts to this processing, first, the rotation speed sensor 27
The engine speed NE is detected via (step 100). Thereafter, the value of the detected engine circuit speed NE is judged (steps 100 to 120), and the VSV 30 is controlled to be turned on / off according to the engine speed NE.

That is, during idle operation when the engine speed NE is less than the predetermined value NE2 (step 110), or during fuel cut control processing when the engine speed NE exceeds the predetermined value NEO (> NE2) (step 120), the VSV 30 is turned on. When the engine speed NE is output (step 130) and the engine speed NE is equal to or higher than the predetermined value NE2 and equal to or lower than the predetermined value NEO (steps 110 to 120), VS is set.
An off signal is output to V30 (step 140).
The fuel cut control process is performed when the amount of depression of the accelerator pedal 6 (the opening degree of the accelerator lever 25) depressed by the driver is zero and the engine speed NE exceeds a predetermined value NEO in a process (not shown). In addition, it is executed by a known method.

The operation of the electronic control unit for the diesel engine of this embodiment that performs the above processing will be described with reference to the graphs of FIGS. 5 and 6. Here, the graph g1 shown in FIG. 5 shows the relationship between the engine rotational speed NE and the fuel injection amount Qv when the accelerator pedal depression amount of the accelerator pedal 6 is zero.
The drawing is a graph showing the relationship between the engine speed NE and the intake pipe pressure PM. The graphs g2 and g shown in FIG.
3 shows the relationship between the engine rotation speed NE and the fuel injection amount Qv when the accelerator depression amount is 50% and 100% (fully opened), respectively. Further, FIG. 6 shows the intake pipe pressure PM when the main intake throttle valve 3 is fully closed and the auxiliary intake throttle valve 4 is at an intermediate opening degree.

When the driver releases his / her foot from the accelerator pedal 6 to perform deceleration operation, the fuel injection amount Qv injected into the engine 1 is controlled according to the graph g1 in FIG. 5, as is well known. That is, the engine speed NE is the predetermined value NE.
Until it decreases to O, the fuel injection amount Qv is set to zero due to the execution of the fuel cut control process described above, and when it falls below the predetermined value NEO, the engine speed NE is kept in order to keep it within the predetermined range. The fuel injection amount Qv is gradually increased as the speed NE decreases. At this time, as shown in the graph of FIG. 6, the intake pipe pressure PM is equal to the engine rotation speed N.
The higher E is, the more negative it is. When the intake pipe pressure PM is less than or equal to the predetermined value P1, it means that the amount of air taken in is insufficient, which causes a so-called misfire phenomenon. Intake pipe pressure PM
As shown in the figure, the state where is the predetermined value P1 corresponds to the state where the value of the engine rotation speed NE is the predetermined value NE2. As a result, when the engine rotational speed NE is decelerated by the predetermined value NE2 or more, when the auxiliary intake throttle valve 4 is in the intermediate opening state, the intake air becomes insufficient to cause a misfire and a white smoke is generated. Therefore, the engine speed NE is equal to the predetermined value NE2.
During the above deceleration, it is necessary to open the auxiliary intake throttle valve 4 to an intermediate opening degree or more, but when the engine rotation speed NE exceeds a predetermined value NEO (> NE2), the fuel injection amount Qv
Is zero.

Here, in the present embodiment, the auxiliary intake throttle valve 4 is throttled to an intermediate opening degree during deceleration when the engine speed NE exceeds a predetermined value NEO, and the auxiliary intake throttle valve is reduced during deceleration below the predetermined value NEO and above the predetermined value NE2. Control to release 4 to full open is performed. Further, the engine speed NE is a predetermined value NE
During deceleration of less than 2 (during idling), the auxiliary intake throttle valve 4 is set to an intermediate opening degree as in the conventional case. Incidentally, FIG. 7 shows
It is a figure explaining the above-mentioned operation. That is, as shown in the figure, in this embodiment, the engine rotation speed NE is the predetermined value NE.
In order to fully open the auxiliary intake throttle valve 4 only during deceleration equal to or less than O and equal to or greater than the predetermined value NE2, V is set only within this range.
The intake throttle signal SG output to the SV 30 is turned off.

According to the electronic control unit for a diesel engine of this embodiment described in detail above, during deceleration when the fuel cut control process is executed, the auxiliary intake throttle valve 4 is not fully opened but is throttled to an intermediate opening degree. As a result, the engine rotation speed NE becomes equal to the predetermined value N.
At the time of deceleration exceeding EO, the intake opening area is narrowed, which has an excellent effect of significantly reducing the vibration and noise of the engine. Further, at this time, since the fuel injection amount Qv is zero, there is no shortage of intake air and white smoke is preferably prevented.

The electronic control unit for the diesel engine according to the present embodiment is not limited to the above embodiment, and can be implemented in various modes without departing from the scope of the present invention. For example, in the present invention, the auxiliary intake throttle valve 4 is configured to have an intermediate opening during the fuel cut control process during deceleration, but the auxiliary intake throttle valve 4 may be further throttled.

Effect of the Invention As described above, in the electronic control unit for a diesel engine of the present invention, when the diesel engine decelerates, the main intake throttle valve is closed and the auxiliary intake throttle valve is fully opened, so that the intake air is reduced during deceleration. Prevents the generation of white smoke due to less air, and throttles the auxiliary intake throttle valve under operating conditions in which white smoke does not occur due to fuel cut by the fuel cut control means even during deceleration. This suppresses the generation of engine vibration and noise. Therefore, according to the present invention, it is possible to surely prevent white smoke from being generated when decelerating the diesel engine, and within a range where white smoke is not generated,
Vibration and noise of the diesel engine can be significantly reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram illustrating the basic configuration of an electronic control unit for a diesel engine according to the present invention, and FIG. 2 is an engine peripheral portion of the electronic control unit for a diesel engine according to an embodiment of the present invention. FIG. 3 is a schematic block diagram showing the configuration of an electronic control unit (ECU), FIG. 4 is a flowchart showing a process of an “intake throttle control routine”, and FIG. 5 is an engine rotation at a predetermined accelerator depression amount. FIG. 6 is a graph showing the relationship between the speed NE and the fuel injection amount Qv, FIG. 6 is a graph showing the relationship between the engine speed NE and the intake pipe pressure PM, and FIG. 7 is an operation explanatory diagram. 1 ... Engine 2 ... Intake pipe 3 ... Main intake throttle valve 4 ... Sub intake throttle valve 5 ... Vacuum sensor 6 ... Accelerator pedal 8 ... Diaphragm device 16 ... Exhaust pipe 25 ... Accelerator lever 26 ... … Injection pump 27 …… Rotation speed sensor 30,31 …… Vacuum switching valve (VS
V) 35 ... Electronic control unit (ECU)

Claims (1)

[Scope of utility model registration request] 1. An intake opening area of a diesel engine is adjusted by a main intake throttle valve provided in a main intake passage and an auxiliary intake throttle valve provided in an auxiliary intake passage bypassing the main intake throttle valve, Intake throttle control means for closing the main intake throttle valve and fully opening the auxiliary intake throttle valve during deceleration of the diesel engine; and during deceleration of the diesel engine and at a predetermined rotation speed of the diesel engine. An electronic control unit for a diesel engine, comprising: a fuel cut control means for performing a fuel cut at a speed equal to or higher than a speed; wherein the intake throttle control means is performing fuel cut by the fuel cut control means, An electronic control unit for a diesel engine, comprising a compensating means for throttling an auxiliary intake throttle valve.