JPH037026B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a glow plug energization control method for a diesel engine, and in particular, a method suitable for controlling the amount of energization of a glow plug that ignites fuel injected into a combustion chamber of a diesel engine by energizing it. This invention relates to a glow plug energization control method for a diesel engine.

Vehicles such as automobiles equipped with diesel engines are equipped with glow plugs that ignite fuel injected into the combustion chamber of the diesel engine by applying electricity. Conventionally, when controlling the energization of the glow plug, the engine water temperature is detected, the energization time is determined according to the engine water temperature, and the amount of energization to the glow plug is increased during this energization time. Control was performed to maintain the temperature of the glow plug above a set temperature required for igniting the fuel. Therefore, when starting the engine, the fuel injected into the combustion chamber by the glow plug is raised to a temperature suitable for igniting the fuel, making it easier to start the engine.

By the way, when a vehicle travels on a highland where atmospheric pressure is low, the intake pressure of the engine decreases, and pump loss (work loss in intake and exhaust) increases. Therefore, in vehicles where conventional glow plug energization control is applied, the amount of energization to the glow plug is not controlled by the engine's intake pressure, so the ignitability of the fuel decreases significantly due to a decrease in compression pressure. There was a problem. When such a problem occurs, unburned gas becomes white smoke and is discharged from the exhaust pipe. This white smoke is accompanied by a strange odor and also contains harmful gases such as HC, CO, and NOX, which pollutes the atmosphere.

In addition, even if the vehicle is not traveling at high altitudes where atmospheric gas levels are low, in the case of a vehicle equipped with a diesel engine equipped with an intake throttling system, control is performed to throttle the intake air to reduce noise and vibration. This caused a problem in that the intake pressure of the engine decreased, the ignitability of the fuel tended to decrease, and white smoke was generated.

On the other hand, an engine system has been proposed that corrects the fuel injection timing based on the engine intake pressure in order to prevent the generation of white smoke due to a decrease in the ignitability of the fuel. If this was done to prevent white smoke, there was a problem that the engine would become knocking.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to provide a glow plug energization control method for a diesel engine that can improve the ignitability of fuel and completely burn the fuel. be.

To achieve the above object, the present invention detects the intake pressure of an engine, compares this engine intake pressure with a set value of the engine intake pressure indicating a limit value at which fuel misfire occurs, and detects the detected engine intake pressure. The present invention is characterized in that when the pressure is below the set value, electricity is supplied to the glow plug that ignites the fuel injected into the combustion chamber of the diesel engine.

Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 1 shows a configuration diagram of a fuel injection pump and a control device suitable for applying the present invention.

The fuel injection pump 1 is composed of a drive control section and a sensor section. The drive control unit includes a drive shaft 1 driven by a diesel engine 10.
1. A gear 12 and a roller 13 provided at the end of the drive shaft 11, a cam plate 14 loosely fitted to the roller 13, a spill port 50 inside, and a diesel engine connected to the cam plate 14. Pump plunger 1 for delivering fuel to 10 injection exit nozzles 2
5. A fuel pump 17 that sends fuel to the injection nozzle 2 and the timer piston 16, a timing control valve 19 that determines advance angle adjustment, and a spill ring 21.
Supply of fuel to the linear solenoid 22 that drives the linear solenoid 22, the plunger 24 that drives the coil 23 and the spill ring 21 that constitute the linear solenoid 22, the spill ring 21 that is driven by the linear solenoid 21 to adjust the injection amount, and the pump plunger 15. Fuel cut valve (hereinafter referred to as
(referred to as FCV) 26 (composed of an excitation coil 27 and a valve 28), a delivery valve 56 for preventing backflow of fuel from the pump plunger 15 and prevention of dripping, and a regulating valve 29.

The sensor section includes a timer position sensor 18 that electrically detects the position of the timer piston 16, and an electromagnetic pickup sensor 2 that serves as a rotation speed detector that outputs a pulse signal according to the rotation speed of the gear 12.
0, and a spill position sensor 25 that detects the amount of movement of the plunger 20.

The cam plate 14 rotates and reciprocates together with the pump plunger 15. This reciprocating motion is caused by the cam plate 14 riding on the roller 13, which is rotatable but fixed in the axial direction of the shaft. The fuel is distributed by rotating the pump plunger 15. The adjustment of the fuel injection amount is determined by the position of the spill ring 21 and the timing at which the highly compressed fuel is released by the pump plunger 15. Further, excess fuel in the pump is returned to the pump 13 via the orifice 30. Also, the linear solenoid 2 in the fuel pump 1
The control device 2 and the FCV 26 are controlled by the control device 3, and for this purpose, output signals from various sensors are taken in. That is, electromagnetic pickup sensor 2
The engine rotational speed signal S _N at 0 and the output signal S _S of the spill position sensor 25 are taken into the control device 3 .

The control device 3 also receives a detection signal S _A from an intake air temperature sensor provided in the intake manifold 4, a detection signal S _P from an intake pressure sensor 6 also provided in the intake manifold 4, and a detection signal S P from a water temperature sensor that detects engine cooling water temperature. A signal S _W , a detection signal Sacc from the accelerator sensor unit 9 that detects the amount of depression of the accelerator 8 , an ignition signal Ig that is a signal corresponding to the on/off state of the ignition switch 40 , and an on/off state of the starter switch 42 A starter signal St, which is a corresponding signal, is supplied respectively. The control device 3 takes in detection signals etc. from various sensor groups,
The driving of the fuel injection pump 1 and the diesel engine 10 can be controlled based on these signals.

Further, the intake manifold 44 of the diesel engine 10 is provided with a glow plug 46 that ignites fuel injected into the combustion chamber of the diesel engine 10 by applying electricity. The amount of current supplied to the glow plug 46 is controlled by the glow plug energization rotation 48, and the injected fuel can be heated in accordance with the amount of current supplied. Further, the amount of current supplied by the glow plug current supply rotation 48 is controlled by a command from the control device 3.

FIG. 2 shows a configuration diagram in which the control device shown in FIG. 1 is configured with a microcomputer.

The control device 3 shown in FIG. 2 has a CPU 61 as its core, and stores processing programs and monitor programs for executing various processes.
ROM 62, RAM having a backup memory that temporarily stores calculation contents and output contents of various sensors, etc., and continues to store calculation contents setting values, etc. even when the power is turned off; input/output ports 64, 65;
It consists of an A/D converter 66, a multiplexer 67, drive rotations 68, 69, 70, etc., input/output ports 64, 65, CPU 61, ROM 62,
The RAMs 63 are connected to each other by bus lines 71. Detection signals from the water temperature sensor 7, intake temperature sensor 5, intake pressure sensor 6, and accelerator sensor 9 are supplied to a multiplexer 67 via buffer circuits 72, 73, 74, and 75. Further, detection signals from the spill position sensor 25 and the timer position sensor 18 are supplied to the multiplexer 67 via sensor signal detection circuits 76 and 77. The sensor output supplied to the multiplexer 67 is converted into a digital signal by the A/D converter 66 and supplied to the input/output port 64 as data. Further, the starter signal St and the ignition signal Ig are supplied to the input/output port 65 via buffer circuits 78 and 79, respectively. Further, the detection signal of the electromagnetic pickup sensor 20 is supplied to the CPU 61 via a waveform shaping circuit 80.

Further, in order to detect the amount of current supplied to the glow plug 40, a signal from a sensing resistor _R1 provided in the energization circuit of the glow plug 46 is supplied to the multiplexer 67 via the voltage detection circuit 82.

The CPU 61 performs various calculations based on signals from the various sensors, etc., and outputs a drive signal for driving the energization amount of the glow plug 46, the fuel pump, etc. That is, when controlling the amount of current to the glow plug 46, a drive signal is supplied to the drive circuit 68, and when controlling the drive of the FCV 26, a drive signal is supplied to the drive circuit 69. Further, when driving the linear solenoid 22, a driving signal is supplied to the driving circuit 70 via the D/A converter 84 and the servo amplifier 86. In addition, CPU61, input/output port 6
4, 65, A/D converter 66, D/A converter 84
clock circuit 90 for sending clock pulses to
is provided.

FIG. 3 shows a configuration diagram for explaining the specific configuration of the glow plug energizing circuit 48.

The glow plug energizing circuit 48 includes a sensing resistor R ₁ , a glow plug resistor R ₆ , and a relay 10
0, the relay 102, and the sensing resistor R ₁ is the equivalent resistance R ₂ of the glow plug 46,
Connected to R ₃ , R ₄ , and R ₅ . Relay Ry ₁ , Ry ₂
The excitation coils L ₁ and L ₂ are connected to the drive circuit 68 of the control device 3, respectively, and the sensing register
Both ends of R ₁ are connected to a voltage detection circuit 82 .
Furthermore, the equivalent resistances R ₂ , R ₃ , R ₄ , and R ₅ are constructed of resistors whose resistance values increase as the amount of current increases. Also, the resistance value of glow plug resistor _R6 is
0.1Ω, the resistance value of sensing resistor _R1 is 10mmΩ,
The resistance values of the equivalent resistances R ₂ to R ₅ are 0.6 to 0.8Ω.

The glow plug energizing circuit 48 in this embodiment configured as described above controls the amount of current supplied to the glow plug 46 by controlling the operation of the relays Ry ₁ and Ry ₂ using the drive signal from the drive circuit 68. The temperature of the glow plug 46 can be maintained within the set temperature range. That is, when the relays Ry ₁ and Ry ₂ are activated by the drive signal from the drive circuit 68,
_Only sensing resistor R1 is glow plug 48
The amount of current required to rapidly heat the glow plug 46 is included in the current-carrying circuit of the sensing resistor _R1.
are supplied to the equivalent resistances R ₂ to R ₅ through. As a result, when the temperature of the glow plug 46 increases rapidly, the resistance values of the equivalent resistances R ₂ to R ₅ increase, and as a result, the amount of current flowing to the glow plug 46 decreases, so the voltage drop across the sensing resistor R ₁ decreases. .

To determine whether the temperature of the glow plug 46 is within a set temperature range, for example 750°C to 900°C, a voltage detection circuit detects the voltage applied to the sensing resistor _R1 and the voltage drop across the sensing resistor _R1 . This can be done by detecting at 82.

That is, in this embodiment, although the voltage applied to the sensing resistor R ₁ is different when the relay Ry ₁ is activated and when it is not activated, the equivalent resistance when the temperature of the glow plug 46 changes over the set temperature range is
The voltage drop of R ₂ to _{R 5} is measured by sensing resistor R ₁ when relay Ry ₁ is activated and when it is not activated, respectively.
By setting in advance the voltage applied to the glow plug 46 and the voltage drop across the sensing resistor _R1 with respect to the applied voltage, it is detected whether the temperature of the glow plug 46 is within the set temperature range. be able to.

Therefore, if the voltage detection circuit 82 detects that the temperature of the glow plug 46 exceeds the set temperature (900°C) and stops the operation of the relay Ry ₁ , the glow plug resistor is connected to the energizing circuit of the glow plug 46. R ₆ is included, the amount of current flowing through the equivalent resistances R ₂ to _{R 5} is reduced, and the temperature of the glow plug 46 can be lowered. Also, when relay Ry ₁ is not activated, the temperature of glow plug 46 decreases and the sensing resistor
Even if the voltage drop across _R1 increases, the temperature of the glow plug ₄₆ can be adjusted _to the set temperature (750
It is possible to detect when the temperature drops below ℃).
At this time, by activating the relay Ry ₁ again, the amount of electricity supplied to the glow plug 46 can be increased, and the temperature of the glow plug 46 can be raised.

By repeating the operation of the relay Ry ₁ in this manner, the temperature of the glow plug 46 can be maintained within the set temperature range.

By the way, in a diesel engine, as shown in Fig. 4, the engine rotation speed (rpm)
Depending on the engine intake pressure (mmHgabs (absolute pressure)), there is a region where white smoke is generated. Therefore, in this embodiment, as shown in FIG. 5, a set value Pk of the engine intake pressure as a limit value at which fuel misfire occurs is stored in the ROM 62 in association with the engine rotational speed (rpm).
Then, the engine speed and intake pressure of the engine are detected to determine whether or not the engine is in a region where white smoke is generated.

Next, the operation according to the present invention will be explained based on the flowchart of FIG.

First, in step 100, the engine rotation speed N _E is determined by the detection signal from the electromagnetic pickup sensor 20, the intake pressure Pm is determined by the detection signal from the intake pressure sensor 6, and the temperature T _G of the glow plug 46 is determined by the detection signal from the voltage detection circuit 82. Each is detected and the process moves to sterop 101. In step 101, an intake pressure set value Pk indicating a limit value at which fuel misfire occurs is calculated from the engine rotational speed N _E , and the process moves to step 102. In step 102, the detected intake pressure
It is determined whether Pm is smaller than the set value Pk of the intake pressure. In step 102, the inspiratory pressure
If Pm is smaller than the set value Pk, step 103
, and activate relays Ry ₁ and Ry ₂ . Next, the process moves to step 104, and it is determined whether the temperature T _G of the glow plug 46 is lower than the set temperature, for example, 900°C. In step 104, the glow plug 46
If the temperature T _G is lower than the set temperature, step
Step 105 continues the operation of the relay Ry ₁ by the drive signal from the drive circuit 68. Furthermore, at this time,
Relay Ry ₂ is also activated. Therefore, the amount of electricity applied to the glow plug 46 increases and the glow plug 46
temperature increases.

If the determination in step 104 is NO, the process moves to step 106, where the drive signal from the drive circuit 68 is stopped and the excitation coil LI is brought into a non-excited state. Therefore, a smaller current is supplied to the glow plug 46 than when the excitation coil LI is in the excited state, and the temperature of the glow plug 46 gradually decreases.

On the other hand, if the determination in step 102 is NO, the process moves to step 107. In this step, the relay
No drive signal is output to Ry ₁ and Ry ₂ , and both relays Ry ₁ and Ry ₂ are in an inactive state.

In this way, in this embodiment, the glow plug is energized when the intake pressure is below the set pressure, and when the temperature of the glow plug is below the set temperature, the glow plug is rapidly heated and the temperature of the glow plug is decreased. The temperature of the fuel is raised to within the set temperature, and even if the intake pressure falls below the set pressure, it is possible to prevent the fuel from misfiring.

Furthermore, if the glow plug energization control method of this embodiment is applied to a vehicle equipped with an engine equipped with an intake throttle system, even if the intake throttle is controlled to increase, fuel misfires can be prevented. can.

Furthermore, by applying the glow plug energization control method of this embodiment, it is possible to prevent the generation of white smoke due to fuel misfire without performing control to correct the injection timing based on the intake pressure of the engine.

Furthermore, according to this embodiment, misfires of the fuel can be prevented and the fuel can be completely combusted, so that torque can be improved and fuel efficiency can be improved.

Furthermore, in the above embodiment, it has been described that the glow plug is energized by detecting the engine rotational speed and the engine intake pressure, but only the engine intake pressure is detected and the limit value at which fuel misfire occurs A set value of the intake pressure indicating the set value is determined in advance, this set value is compared with the detected intake pressure, and the glow plug is energized when the intake pressure of the engine is equal to or lower than the set value. The same effect can be obtained. Furthermore, the engine load range in which the fuel misfires occurs is determined in advance from the engine rotation speed and the fuel injection amount (accelerator opening), the engine rotation speed and the fuel injection amount are detected, and the engine is controlled based on these detection signals. Even if the glow plug is energized when the load reaches the set load range, the same effect as in the embodiment described above can be obtained.

Further, in the above embodiment, when the engine water temperature is cold, even better control can be achieved by increasing the set value of the engine intake pressure from, for example, 720 mmHgabs to 800 mmHgabs.

As explained above, according to the present invention, even if the intake pressure of the engine falls below the set intake pressure that indicates the limit value at which fuel misfire occurs, the fuel misfires and white smoke is generated. It has the excellent effect of preventing

[Brief explanation of drawings]

FIG. 1 is a configuration diagram for configuring a fuel injection pump and a control device to which the present invention is applied, FIG. 2 is a configuration diagram for explaining the configuration of the control device shown in FIG. 1,
Fig. 3 is a block diagram for explaining the configuration of the glow plug energizing circuit shown in Fig. 1, and Fig. 4 is a diagram for explaining the white smoke generation area caused by the relationship between engine speed and engine intake pressure. FIG. 5 is a diagram showing the relationship between engine intake pressure and engine rotational speed, and FIG. 6 is a flowchart for explaining the operation of the present invention. DESCRIPTION OF SYMBOLS 1... Fuel injection pump, 2... Injection nozzle, 3... Control device, 6... Intake pressure sensor, 7... Water temperature sensor, 20... Electromagnetic pickup sensor, 40... Ignition switch, 4
2... Starter switch, 46... Glow plug, 48... Glow plug energizing circuit.

Claims (1)

[Claims] 1. Detect the intake pressure of the engine, compare this engine intake pressure with a set value of the engine intake pressure indicating the limit value at which fuel misfire occurs, and set the detected engine intake pressure to the set value. A method for controlling energization of a glow plug in a diesel engine, which comprises energizing a glow plug that ignites fuel injected into a combustion chamber of a diesel engine in the following cases. 2. The glow plug energization control method for a diesel engine according to claim 1, wherein the set value of the intake pressure is determined from the engine rotation speed.