JPH0351909B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for controlling energization of a glow plug in a diesel engine, and in particular, is suitable for use in an automobile diesel engine equipped with an intake throttle valve and an electronically controlled fuel injection device. The present invention relates to an improvement in a method for controlling energization of a glow plug in a diesel engine by controlling the state of the glow plug.

[Conventional technology]

Generally, in a diesel engine, the fuel supplied to the combustion chamber is controlled by a fuel injection pump that is driven to rotate in synchronization with the engine rotation, and the feed pump installed in the fuel injection pump is used to control the fuel supplied to the combustion chamber. The timing of fuel injection is controlled by using pressure to move a timer and a roller ring, and the amount of fuel injection is controlled by moving a spill ring using a centrifugal governor to change the end of pumping. That's what I do. However, in the past, both the timer and spelling were mechanically controlled;
It has been difficult to perform precise fuel injection amount control. On the other hand, in recent years, with the development of electronic control technology, particularly digital control technology, attempts have been made to electronically control the fuel injection amount of diesel engines. Such electronic control has a feature that it is possible to inject an optimal amount of fuel at an optimal fuel injection timing depending on engine operating conditions such as engine speed and engine load.

[Problem to be solved by the invention]

In such electronic control, when the vehicle is decelerating, the spill ring of the fuel injection pump is
Although the system is controlled to a position where no fuel is injected, in reality, the amount of fuel injected does not become completely zero due to leakage of the fuel injection pump or the like. Further, due to variations in parts and changes over time, the amount of leakage injection described above varies greatly. If the intake pressure decreases due to driving at high altitudes in such conditions, the pressure within the combustion chamber will not rise to the ignition point, and the chamber temperature will decrease, worsening ignition performance, resulting in a decrease in leakage injection amount. There were problems in that a large amount of white smoke was emitted without being combusted, resulting in an increase in HC, a harmful component in the exhaust gas, and the generation of strange odors. In particular, diesel engines are equipped with an intake throttle valve that opens and closes in conjunction with the accelerator pedal in order to reduce idling vibration and improve the operating feel when the engine is stopped. Even when the vehicle is running, a similar problem occurs due to the intake throttle valve being closed. Furthermore, in order to prevent engine stall when the vehicle decelerates, a technology has been proposed in which the amount of fuel injection is reduced more slowly than the rate of decrease of the required injection amount, providing a so-called dart pot function. , when driving at high altitudes, or in diesel engines equipped with an intake throttle valve, when the intake throttle valve is closed even during general driving such as driving on flat ground, the intake Since a large amount of fuel is injected while the pressure is decreasing, the unburned fuel is discharged as white smoke. Therefore, in the past, there was a problem in that the dart pot could not be used sufficiently to prevent the generation of white smoke. On the other hand, in recent years, in order to improve the startability of a diesel engine and the idling stability immediately after starting, for example, both a large current and a small current are applied to the glow plug from the time the ignition switch is turned on until the start is turned off. , the large current is stopped when the starter is turned off, and the small current is also stopped after a predetermined period of time that varies depending on the engine coolant temperature after the starter is turned on. , a method for controlling energization of glow plugs in diesel engines has been considered. However, in the past, the glow plug energization control as described above was performed only at and immediately after starting the engine, and was not particularly performed during deceleration or during the operation of the dart pot as described above. The present invention has been made to solve the above-mentioned conventional problems, and is capable of preventing the generation of white smoke during deceleration when the intake throttle valve is throttled or when the dart pot is operating. The purpose is to provide a control method.

[Means to solve the problem]

The present invention provides a glow plug energization control method for a diesel engine that includes an intake throttle valve for controlling the amount of intake air and also controls the energization state of the glow plug according to the engine operating state. As shown in the figure, during deceleration with the intake throttle valve being throttled or while the dart pot is operating, the propeller plug is energized to raise the temperature within the engine combustion chamber, thereby solving the above problem. . Also, during deceleration with the intake throttle valve being throttled or during operation of the dart pot, a small current is applied to the glow plug, so that the glow plug can be heated for a long time. Alternatively, during deceleration with the intake throttle valve being throttled or during operation of the dart pot, a large current is applied to the glow plug for a predetermined period of time;
This is designed to improve responsiveness.

【Example】

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an electronic control device for an automobile diesel engine, in which a method for controlling energization of a diesel engine glow plug according to the present invention is adopted, will be described in detail with reference to the drawings. In this embodiment, as shown in FIG. 2, the main intake throttle is arranged in a main intake passage 12 of a diesel engine 10 and rotates in conjunction with, for example, an accelerator pedal 14 operated by a driver. valve 16;
A sub-intake passage 1 that bus-passes the main intake passage 12
8 is a sub-intake throttle valve 20 for reducing idle vibration by throttling intake air during idle.
, a drive shaft 24 that rotates in conjunction with the rotation of the output shaft of the diesel engine 10, and a field pump 26 for pumping fuel that is fixed to the drive shaft 24 (FIG. 2 shows a state rotated by 90 degrees). ), the fuel pressure adjustment valve 28 for adjusting the fuel supply pressure, and the rotational displacement of the gear 30 fixed to the drive shaft 24.
A rotation speed sensor 32 consisting of, for example, an electromagnetic pickup, for measuring the time required for the drive shaft 24 to rotate by a predetermined crank angle to detect the rotation speed of the diesel engine 10, and a rotation speed sensor 32 for controlling the fuel injection timing. A roller ring 34, a timer piston 36 for driving the roller ring 34, a timing control valve 38 for controlling the position of the timer piston 36, and a variable inductor sensor for detecting the position of the timer piston 36, for example. a timer position sensor 40, a spill ring 42 for controlling the fuel injection amount, and a plunger 4 for driving the spill ring 42.
4a, a compression spring 44b, a coil 44c, and a coil case 44d.
4. A spill position sensor 46 consisting of, for example, a variable inductance sensor, for detecting the position of the spill ring 42 from the displacement of the plunger 44a, and a fuel cut solenoid (hereinafter referred to as FCV) for cutting off fuel when the engine is stopped.
48, a fuel injection pump 22 having a plunger 50 and a delivery valve 52; an injection nozzle 54 for injecting the fuel discharged from the delivery valve 52 of the fuel injection pump 22 into the auxiliary fuel chamber of the diesel engine 10; Intake pipe 56
An intake pressure sensor 58 for detecting the pressure of intake air taken in through the engine, an intake air temperature sensor 60 for similarly detecting the temperature of the intake air, and an intake temperature sensor 60 disposed in the cylinder block 10a of the diesel engine 10. A cooling water temperature sensor 62 for detecting the engine cooling water temperature, an accelerator sensor 66 for detecting the depression angle of the accelerator pedal 14 (hereinafter referred to as accelerator opening degree), and the engine combustion chamber 10b are heated to ignite. Both a large current and a small current are energized to the glow plug 67 for increasing the performance, and from when an ignition switch (not shown) is turned on until a starter switch (not shown) is turned off. After the starter switch is turned off, the large current is stopped, and after the starter switch is turned on, the small current is also stopped after a predetermined period of time depending on the engine coolant temperature has passed since the starter switch is turned on. Determine the target injection timing and calculated injection amount based on the engine load detected from the output of the accelerator sensor 66, the engine rotation speed detected from the output of the rotation speed sensor 32, the engine coolant temperature detected from the output of the coolant temperature sensor 62, etc., The timing control valve 38 and the spill actuator 4 are controlled so that the calculated injection amount of fuel is injected from the fuel injection pump 22 at the target injection timing.
Electronic control unit (hereinafter referred to as ECU) that controls
In the electronic control device for an automobile diesel engine 10, the electronic control device is equipped with the above-mentioned
In the ECU 68, during deceleration with the main intake throttle valve 16 being throttled or during the dumppot operation, a small current is applied to the glow plug 67 to raise the temperature in the engine fuel chamber. In the figure, 35 is a gum plate and 43 is a tension spring. The ECU 68, as shown in detail in FIG.
A central processing unit (hereinafter referred to as a CPU) consisting of a microcomputer, for example, that performs various arithmetic processing.
) 69, the output of the cooling water temperature sensor 62 which is input via a buffer 70, the output of the intake air temperature sensor 60 which is input via a buffer 72, and the output of the intake pressure sensor 58 which is input via a buffer 74. , driven by the sensor driving frequency signal of the output of the accelerator sensor 66 and the output of the sensor driving circuit 78 inputted via the buffer 76,
The spill position sensor 46 output is input via the sensor signal detection circuit 80, and the timer position is driven by the sensor drive frequency signal output from the sensor drive circuit 82 and input via the sensor signal detection circuit 84. A multiplexer 86 for sequentially taking in the sensor 40 output, etc., and an analog-to-digital converter (hereinafter referred to as
(referred to as an A/D converter) 88, an input/output port 90 for inputting the output of the A/D converter 88 to the CPU 69, and an input/output port 90 for inputting the output of a starter switch 92 inputted via a buffer 94, etc. an input/output port 96, a waveform shaping circuit 98 for shaping the output of the rotational speed sensor 32 and inputting it into the CPU 69, a clock generation circuit 102, and a CPU 69;
A random access memory (hereinafter referred to as RAM) 104 including a backup random access memory (hereinafter referred to as backup RAM) for temporarily storing calculation data etc. in 69, and a control program and Read-only memory (hereinafter referred to as ROM) 106 for storing various data, etc.
And, according to the calculation result in the CPU 69,
A drive circuit 112 for driving a glow sub-relay 114 for passing a small current through the glow plug 67 and a glow main relay 116 for passing a large current through the glow plug 67, and a current supply circuit for the glow plug 67. a voltage detection circuit 120 for detecting the voltage across a sensing resistor 118 inserted in series with the sensor and feeding it back to the drive circuit 112;
The drive circuit 122 for driving the FCV 8 and the drive circuit 122 for driving the FCV
a drive circuit 124 for driving 48;
According to the deviation between the CPU 69 output and the spill position sensor 46 output, the spill actuator 4
4 and a servo amplifier 126 and a drive circuit 128. In FIG. 3, 130 indicates a glow plug 67 when a small current is applied.
This is a glow plug resistor for limiting the current flowing to the The action will be explained below. The glow plug energization control in this embodiment is executed according to the flowchart shown in FIG. That is, in the CPU 69 of the ECU 68, first,
In step 1010, for example, the accelerator pedal 14
is fully closed, and the engine speed NE
is greater than or equal to a predetermined value, it is determined whether or not the vehicle is decelerating. If the determination result is negative, the process proceeds to step 1020, where, for example, if the fuel injection amount has been increased during deceleration or if the engine rotational speed has decreased by more than a predetermined amount, the fuel injection amount is set to increase. By checking the dashpot flag displayed, it is determined whether or not the dashpot is in operation. In this embodiment, the main intake throttle valve 16 is configured to open and close in conjunction with the accelerator pedal, so when the above conditions are met and it is determined that the vehicle is decelerating or the dart pot is operating, the main intake throttle valve 16 is opened and closed in conjunction with the accelerator pedal. The intake throttle valve 16 is already in a throttled state. If the judgment result is negative, that is, if the vehicle is not decelerating or the dart pot is operating, the step
Proceeding to 1030, the grouter brake 114 is turned off, as in the conventional case, and this routine ends. On the other hand, if the determination result in step 1010 or 1020 is positive, that is, if the vehicle is decelerating or the dart pot is operating, step 1040 is performed.
Then, the glow sub-relay 114 is turned on, a small current is applied to the glow plug 67, and the temperature of the engine combustion chamber 10b is raised to improve the ignitability, and this routine ends. In this embodiment, the glow plug sub-relay 114 is turned on during deceleration (when the main intake throttle valve 16 is throttled) or during the dart pot operation, so the glow plug 67 is not heated for a long time. However, there are no particular problems and the control is simple. Note that the method of energizing the glow plug is not limited to this, and responsiveness can also be improved by, for example, turning on the glow main relay 116 for a predetermined period of time. Further, in the embodiment described above, the glow sub relay 114 was simply turned on both during deceleration and when the dart pot was in operation, but for example, during deceleration, the engine rotation speed is The larger the amount of fuel injection, the greater the amount of electricity applied to the glow plug 67. Also, while the dumppot is in operation, the amount of electricity applied to the glow plug 67 is set as the amount of fuel injection becomes larger, depending on the amount of fuel injection. It is also possible to make it larger. In the embodiment described above, a main intake throttle valve 16 that opens and closes in conjunction with opening and closing of the accelerator pedal is provided, and a sub-intake throttle valve 20 is also provided for special control mainly during idling. However, the present invention does not limit the configuration of the intake throttle valve. However, during deceleration with the intake throttle valve throttled, or when the dart pot is operating,
The present invention will be applied.

【Effect of the invention】

As explained above, according to the present invention, ignition performance is improved during deceleration or when the dart pot is operating with the intake throttle valve being throttled, and white smoke can be reduced during deceleration or when the dart pot is operating. It has the excellent effect of preventing the increase in HC, which is a harmful component in exhaust gas, and the generation of off-odors.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing the gist of the glow plug energization control method for a diesel engine according to the present invention;
FIG. 2 is a cross-sectional view, partially including a block diagram, showing the structure of an electronic control device for an automobile diesel engine in which the diesel engine glow plug energization control method according to the present invention is adopted; The figure is a block diagram including a partial circuit diagram showing the configuration of the electronic control unit used in the above embodiment, and FIG. 4 is a flowchart showing a routine for controlling glow plug energization. . 10... Diesel engine, 14... Accelerator pedal, 16... Main intake throttle valve, 20... Sub-intake throttle valve, 22... Fuel injection pump, 32... Rotational speed sensor, 66... Accelerator sensor, 67...
...Glow plug, 68...Electronic control unit (ECU), 69...Central processing unit (CPU), 1
12... Drive circuit, 114... Glow sub relay, 118... Sensing register, 120
...Voltage detection circuit, 130...Glow plug resistor.

Claims (1)

[Scope of Claims] 1. A glow plug energization control method for a diesel engine that includes an intake throttle valve that controls the amount of intake air and controls the energization state of the glow plug according to the engine operating state, wherein the intake throttle valve During deceleration with the valve throttled or when the dart pot is operating, the glow plug is energized,
A method for controlling energization of a glow plug in a diesel engine, characterized by increasing the temperature within an engine combustion chamber. 2. Claim 1, wherein a small current is applied to the glow plug during deceleration with the intake throttle valve being throttled or when the dart pot is operating.
A method for controlling energization of a glow plug in a diesel engine as described in . 3. The glow plug of the diesel engine according to claim 1, wherein a large current is applied to the glow plug for a predetermined period of time during deceleration with the intake throttle valve being throttled or during operation of the dart pot. Control method.