JP2000220502A - Control device for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress exhaust of black smoke under abrupt acceleration without deteriorating motive power performance of a diesel engine. SOLUTION: This diesel engine 1 has a rotation sensor 6 which outputs a signal in response to rotational speed of the engine 1 and an acceleration sensor 7 which outputs a signal in response to an accelerator opening. A reference injection amount is calculated based on the present engine speed and the accelerator opening obtained from the input of the signals of the sensors 6, 7. A transient injection amount is calculated based on the present engine speed and its variation rate. Both injection amounts are compared with each other. In response to less injection amount, a control signal is output to a fuel injection device 4 by means of a control unit 5. It is thus possible to suppress a fuel injection amount under loadless abrupt acceleration and prevent generation of black smoke.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control system for a diesel engine, and more particularly to a control system for a diesel engine, which is capable of preventing an excessive supply of fuel at the time of no-load sudden acceleration to improve exhaust characteristics and black smoke. The present invention relates to a control device.

[0002]

2. Description of the Related Art In order to suppress black smoke emitted from a diesel engine during rapid acceleration with no load, the injection amount in an extremely low speed rotation range has been conventionally limited. However, since the torque of a diesel engine largely depends on the injection amount, if the amount of black smoke is reduced during rapid acceleration by limiting the injection amount as described above, the torque in the extremely low speed range will decrease. There was a defect that would.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is capable of effectively preventing an excessive supply of fuel during sudden acceleration without deteriorating power performance. It is an object of the present invention to provide a control device.

[0004]

According to a first aspect of the present invention, there is provided a rotation sensor for outputting a signal responsive to an engine speed and a signal responsive to an accelerator opening. An accelerator sensor is provided. Then, while inputting the output signal of the sensor and calculating the reference injection amount based on the current engine speed and the accelerator opening,
A control unit that calculates a transient injection amount based on the current engine speed and its change amount, compares the two injection amounts, and outputs a signal corresponding to the smaller injection amount to the fuel injection device as a control signal. It is characterized by having provided.

According to a second aspect of the present invention, there is provided a rotation sensor for outputting a signal responsive to the number of revolutions of an engine having a turbocharger, an accelerator sensor for outputting a signal responsive to an accelerator opening, and the turbocharger. A wastegate valve for variably operating the opening of the wastegate that bypasses the charger turbine is provided. Then, while inputting the output signal of the sensor and calculating the reference gate opening based on the current engine speed and the accelerator opening, the transient gate opening is calculated based on the current engine speed and the variation thereof. A control unit is provided which compares the two gate openings and outputs a signal corresponding to the larger one as a gate opening signal to the waste gate.

According to a third aspect of the present invention, there is provided a rotation sensor for outputting a signal responsive to the rotational speed of an engine provided with a turbocharger having a variable turbine nozzle, and an accelerator sensor for outputting a signal responsive to an accelerator opening. Is provided. Then, while inputting the output signal of the sensor and calculating the reference nozzle opening based on the current engine speed and the accelerator opening, the transient nozzle opening is calculated based on the current engine speed and the variation thereof. A control unit is provided which compares the two nozzle openings and outputs a signal corresponding to the larger one as a control signal to the control device of the variable turbine nozzle.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a first embodiment of a control apparatus for a diesel engine according to the present invention.
Is installed.

A control unit 5 for controlling an injection pump 4 for supplying fuel to the injection nozzle 3 is provided, and a signal for responding to the engine speed and a signal for responding to the accelerator opening are supplied to the control unit 5. A sensor 6 and an accelerator sensor 7 are provided. 8
Is a pulsar and 9 is an accelerator pedal.

FIG. 2 is a flowchart exemplifying a control process in the control unit 5.
At the same time, based on the signal output from the rotation sensor 6, the rotation speed of the engine 1 is detected and temporarily stored,
In step S2, the accelerator opening is detected based on the signal output from the accelerator sensor 7, and is temporarily stored.

In step S3, a reference injection amount of the engine at that time is calculated based on the current engine speed and the accelerator opening. Then, in step S4, the engine rotation change amount ΔNE is calculated from the difference between the current engine rotation speed and the old engine rotation speed, and in step S5, the transient injection amount is calculated based on the current engine rotation speed and the rotation change amount ΔNE.

In step S6, the reference injection amount calculated as described above is compared with the transient injection amount. If the reference injection amount is not larger than the transient injection amount, the routine proceeds to step 7, where the reference injection amount is injected. When the reference injection amount is larger than the transient injection amount, the process proceeds to step S8, the transient injection amount is adopted as the injection amount, and the process returns to step S1.

That is, the control unit 5 calculates the reference injection amount and the transient injection amount based on the signal output from the rotation sensor 6 and the accelerator sensor 7 responsive to the engine speed and the signal responsive to the accelerator opening. Then, the two injection amounts are compared, and a signal corresponding to the smaller one is output to the fuel injection device as a control signal.

Therefore, in a normal state, the fuel injection amount is determined based on the engine speed and the accelerator opening as in the conventional case. For this reason, the fuel is injected in an amount corresponding to the reference injection amount during the steady operation, so that a sufficient torque can be obtained even in an extremely low speed range, and corresponds to the transient injection amount during the acceleration operation. A quantity of fuel is injected.

On the other hand, when the engine speed change .DELTA.NE is larger than a predetermined value at the time of no-load rapid acceleration, the current engine speed and the current accelerator opening are replaced by the transient injection amount based on the engine speed and the speed change .DELTA.NE. The amount of fuel corresponding to the reference injection amount based on the fuel injection is supplied. For this reason, the acceleration increase as in the normal acceleration operation is not performed, and only an amount of fuel corresponding to the rotation speed and the accelerator opening at that time is injected. Is not performed, and the emission of black smoke is suppressed.

The no-load rapid acceleration operation as described above is performed with no load. For this reason, since the engine speed increases with an increase in the accelerator opening amount without increasing the acceleration based on the current engine speed and the rotation change amount, the opening degree (depressed amount) of the accelerator pedal 9 and the actual There is no discomfort between the engine speeds.

FIG. 3 is a schematic diagram showing a second embodiment in which the control apparatus for a diesel engine according to the present invention is applied to a pressure-accumulation injection type diesel engine. In the present embodiment, a common rail 11 for accumulating and holding the fuel discharged from the supply pump 10 in a high pressure state is provided, and an injector 12 controlled by the control unit 5 is connected to the common rail 11, whereby the first embodiment is used. In the same way as in the case of above, without compromising the responsiveness and stability of the engine under normal operating conditions, it is possible to prevent the excessive supply of fuel at the time of no load sudden acceleration and suppress the emission of black smoke It is.

When the present invention is applied to a pressure-accumulation injection type diesel engine and the control unit controls the injector 12 as described above, if the injection timing is optimally controlled in addition to the control of the injection amount, it is possible to control the injection timing. There is an advantage that the ignition delay can be optimized.

FIG. 4 is a schematic diagram showing a third embodiment in which the present invention is applied to an engine having a turbocharger. In this embodiment, a rotation sensor (not shown) for outputting a signal responsive to the engine speed and an accelerator sensor (not shown) for outputting a signal responsive to the accelerator opening are provided in the same manner as in the above embodiment. In addition, a waste gate 16 for variably operating the opening of the bypass passage 15 of the turbine 14 of the turbocharger 13 is provided.

Reference numeral 17 denotes an air tank, reference numeral 18 denotes a pressure reducing valve, reference numeral 19 denotes an electromagnetic valve controlled by the control unit 5, reference numeral 20 denotes an actuator of the waste gate 16, reference numeral 21 denotes a supply pressure sensor, and an electromagnetic valve 19 connected to the control unit 5. The opening degree of the waste gate 16 is controlled to increase or decrease in response to the air pressure supplied to the actuator 20 via the.

FIG. 5 is a flowchart exemplifying a control process in the control unit 5 in the third embodiment. In step S1, the rotational speed of the engine 1 is detected based on a signal output from a rotation sensor (not shown) to temporarily In step S2, the accelerator opening is detected based on a signal output from an accelerator sensor (not shown) and temporarily stored.

In step S3, a reference gate opening at that time is obtained based on the current engine speed and the accelerator opening, for example, based on the gate map shown in FIG.

Next, in step S4, an engine rotation change ΔNE is calculated from the difference between the current engine speed and the old engine speed. In step S5, based on the gate map shown in FIG. 7, for example, a transient gate opening responsive to the current engine speed and the rotation change amount ΔNE is obtained.

In this embodiment, since the open / close type wastegate 16 is employed, the wastegate 16 is opened (opening degree 100) or closed (opened) as shown in the gate maps shown in FIGS. Although the switching control is performed to any one of the opening degrees 0), the opening degree of the waste gate 16 may be controlled in multiple stages.

In step S6, the reference gate opening obtained as described above is compared with the transient gate opening.
If the reference gate opening is larger than the transient gate opening, the process proceeds to step 7 to output the reference gate opening as a gate opening signal, but if the reference gate opening is not larger than the transient gate opening, step S8. And outputs the transient gate opening as a gate opening signal, and returns to step S1.

That is, the control unit 5 obtains a reference gate opening and a transient gate opening based on signals output from the rotation sensor and the accelerator sensor and responsive to the engine speed and the accelerator opening. The gate opening is compared, and a signal corresponding to the larger opening is output to the solenoid valve 19 as a control signal.

Therefore, in a normal state, the waste gate 1 is determined based on the engine speed and the accelerator opening as in the conventional case.
Since the opening degree is determined, efficient combustion can be obtained. However, at the time of no-load sudden acceleration in which the engine rotation change ΔNE is larger than a predetermined value, the reference based on the current engine speed and the current accelerator opening is used instead of the transient gate opening based on the engine speed and the rotation change ΔNE. A signal corresponding to the gate opening is supplied.

For this reason, the waste gate 16 is not closed and the exhaust pressure does not increase unlike the normal acceleration operation. Therefore, since the combustion gas is efficiently exhausted, smooth air supply is performed, and the emission of black smoke, which is a concern at the time of no-load sudden acceleration, is prevented.

FIG. 8 is a schematic configuration diagram showing a fourth embodiment in which the present invention is applied to an engine provided with a turbocharger having a variable turbine nozzle. In the present embodiment, an actuator 23 that variably controls the opening (angle) of the variable turbine nozzle 22 provided in the turbocharger 13
The solenoid valve 24 for controlling the air pressure supplied to the control unit 5 is controlled by the control unit 5.

In the same manner as in the third embodiment, the reference nozzle opening and the transient nozzle opening are determined based on signals output from the rotation sensor and the accelerator sensor in response to the engine speed and the accelerator opening. After the determination, the two nozzle openings are compared, and a signal corresponding to the larger one is output to the solenoid valve 24 as a control signal.

Therefore, in the normal state, the opening degree of the variable turbine nozzle 22 is determined based on the engine speed and the accelerator opening degree as in the prior art, so that efficient supercharging is performed. On the other hand, at the time of no-load sudden acceleration in which the engine rotation change ΔNE is larger than a predetermined value, a reference based on the current engine speed and the current accelerator opening is used instead of the transient nozzle opening based on the engine speed and the rotation change ΔNE. A signal corresponding to the nozzle opening is supplied.

Therefore, the variable turbine nozzle 22 is not closed and the exhaust pressure does not rise as in the normal acceleration operation, and the combustion gas is efficiently discharged. For this reason, smooth air supply is performed, and black smoke emission, which is a concern during no-load sudden acceleration, is prevented.

In the third and fourth embodiments, the actuators 20 and 23 of the waste gate 16 and the variable turbine nozzle 22 are respectively constituted by air actuators. However, these actuators 20 and 22 are not necessarily shown in the embodiment. However, the present invention is not limited thereto, and for example, a hydraulic actuator or an electric actuator may be employed.

[0033]

As is apparent from the above description, claim 1
According to the invention described in (1), the fuel injection amount is limited during the no-load rapid acceleration operation of the engine. In the Japanese Patent Application Laid-Open No. H11-157, the exhaust gas pressure is reduced by restricting the opening of the waste gate or the opening of the variable turbine nozzle, so that the combustion gas can be efficiently discharged. Therefore, according to the present invention, it is possible to suppress the excessive supply of fuel which is a concern at the time of no-load sudden acceleration without sacrificing the torque in the extremely low speed range, and to prevent the emission of black smoke.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of a diesel engine control device according to the present invention.

FIG. 2 is a flowchart illustrating a control process in a control unit 5;

FIG. 3 is a schematic configuration diagram showing a second embodiment in which the control device for a diesel engine according to the present invention is applied to a pressure-accumulation injection type diesel engine.

FIG. 4 is a schematic configuration diagram showing a third embodiment in which the present invention is applied to an engine having a turbocharger.

FIG. 5 is a flowchart illustrating a control process in a control unit according to the third embodiment.

FIG. 6 is a gate map used in step S3 of FIG.

FIG. 7 is a gate map used in step S5 of FIG.

FIG. 8 is a schematic configuration diagram showing a fourth embodiment in which the present invention is applied to an engine provided with a turbocharger having a variable turbine nozzle.

[Explanation of symbols]

 Reference Signs List 1 diesel engine 2 combustion chamber 3 injection nozzle 4 injection pump 5 control unit 6 rotation sensor 7 accelerator sensor 8 pulser 9 accelerator pedal 10 supply pump 11 common rail 12 injector 13 turbocharger 14 turbine 15 bypass passage 16 wastegate 17 air tank 18 pressure reducing valve 19 Solenoid valve 20 Actuator 21 Supply pressure sensor 22 Variable turbine nozzle 23 Actuator 24 Solenoid valve

Claims (3)

[Claims] 1. A rotation sensor for outputting a signal responsive to an engine speed, an accelerator sensor for outputting a signal responsive to an accelerator opening, and an output signal of the sensor for inputting a current engine speed and an accelerator opening. While calculating the reference injection amount based on the degree, the transient injection amount is calculated based on the current engine speed and its change amount, and then comparing the two injection amounts, the signal corresponding to the smaller injection amount. An air-fuel ratio control device for a diesel engine comprising a control unit that outputs a control signal to a fuel injection device. 2. A rotation sensor for outputting a signal responsive to the rotation speed of an engine provided with a turbocharger, an accelerator sensor for outputting a signal responsive to an accelerator opening, and an opening of a bypass passage of a turbine of the turbocharger. A waste gate for variably operating the engine, and calculating a reference gate opening based on the current engine speed and the accelerator opening by inputting the output signal of the sensor, and a transient gate based on the current engine speed and its change amount. A diesel engine control device comprising: a control unit that calculates an opening degree, compares both gate opening degrees, and outputs a signal corresponding to the larger one to the waste gate as a gate opening signal. 3. A rotation sensor for outputting a signal responsive to the rotation speed of an engine provided with a turbocharger having a variable turbine nozzle, an accelerator sensor for outputting a signal responsive to an accelerator opening, and an output signal of the sensor. Input and calculate the reference nozzle opening based on the current engine speed and accelerator opening, while calculating the transient nozzle opening based on the current engine speed and the amount of change, and then compare both nozzle openings And a control unit for outputting a signal corresponding to the larger opening as a control signal to a control device for the variable turbine nozzle.