JPH0529787B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a white smoke generation prevention device for a diesel engine.

[Prior art] Conventionally, in a diesel engine, ignition is difficult when the combustion chamber is low, so a glow plug attached to the engine cylinder or cylinder head is heated by electricity for a certain period of time, for example, 10 to 20 seconds, just before and after starting the engine. This increases the temperature of the engine combustion chamber.

However, even under stable engine operating conditions after starting, white smoke may be generated when the intake pressure and temperature are low, or white smoke from unburned gas may be generated for which the cause cannot be clearly identified, resulting in fuel efficiency. This was not desirable from the viewpoint of improving the water quality and preventing pollution. As a countermeasure in such a case, it is generally known to raise the temperature of the engine combustion chamber by heating the glow plug with electricity when the temperature in the engine combustion chamber falls below a preset temperature. However, as a practical matter, in order to completely prevent the generation of white smoke, the temperature within the combustion chamber of the engine must be maintained considerably high. Therefore, although it is not necessarily the case that white smoke is generated, it is effective to immediately heat the glow plug with electricity just because the temperature of the engine combustion chamber has dropped, which is effective in preventing the generation of white smoke. Since the power consumption of the plug is extremely large, the generator and battery capacity of the vehicle must be considerably large. This not only increases fuel efficiency and vehicle production costs, but also increases the weight of the vehicle and reduces the driving performance of the vehicle.

[Object of the Invention] The object of the present invention is to almost certainly prevent the generation of white smoke while minimizing the energization time to the glow plug without substantially increasing the production cost, weight, etc. of the vehicle. The object of the present invention is to eliminate the above-mentioned conventional drawbacks by providing a white smoke generation prevention device for a diesel engine that can prevent the generation of white smoke.

[Explanation of Claim Correspondence Diagram] FIG. 1 is an overall configuration diagram for clearly explaining the present invention.

Here, the combustion chamber 2 of the diesel engine 1
A glow plug 3 and a temperature sensor 4 are provided, and a rotation speed sensor 5 is provided in conjunction with the crankshaft of the diesel engine 1. A signal corresponding to the combustion chamber temperature detected by the temperature sensor 4 and a signal corresponding to the engine rotation speed detected by the rotation speed sensor 5 are transmitted to the energization control means 6.
The energization control means 6 prepares in advance a relationship between the engine speed and the combustion chamber temperature at which the glow plug should be energized at that engine speed, such that as the engine speed increases, the combustion chamber temperature also increases. Based on the signals from the temperature sensor and rotation speed sensor, the energization control means 6 energizes the glow plug when the above relationship is satisfied, and cuts off the energization when the relationship is not satisfied.

In addition to the usual combustion chamber between the cylinder head and the piston, the combustion chamber also includes a pre-combustion chamber and a swirl chamber.

[Embodiment] Next, the configuration of an embodiment of the present invention will be described with reference to the drawings.

FIG. 2 shows a schematic diagram of a diesel engine white smoke generation prevention device and its surroundings. That is, 11 is the engine, 12 is the cylinder head 13
15 is an exhaust manifold connected to the exhaust port 14 of the cylinder head 13;
The intake manifold 15 is connected to an intake manifold, and an intake tube 17 connected to the intake manifold 15 is attached with a turbocharger 19 driven by a turbine 18 on the way to the exhaust manifold 12. In addition, the intake tube 17 includes a throttle valve 21 whose opening degree is controlled in conjunction with the accelerator pedal 20, an intake pressure sensor 22, and an air cleaner 23.
is attached to the air cleaner 23, and an intake air temperature sensor 24 is attached to the air cleaner 23. Reference numeral 25 denotes an air bypass passage that bypasses the throttle valve 21. A bypass flow control valve 28 is attached to the air bypass passage 25 and is driven by a diaphragm 27 via a vacuum switching valve 26. The opening degree is controlled by a control means 29 as shown in FIG. 30 is an injection nozzle attached to the cylinder head, and the fuel pumped from the electronic injection pump 31 is transferred to the engine 11.
The fuel is injected into the engine pre-combustion chamber 32 of the engine. 33 is a glow plug for heating the engine pre-combustion chamber 32 attached to the cylinder head 13, and the temperature of the engine pre-combustion chamber 32 is detected by a temperature sensor 34. The cooling water temperature of the engine 11 is determined by the water temperature sensor 35.
The opening degree of the throttle valve 21 is detected by the accelerator sensor 36. In addition, 37 is a linear solenoid that controls the spill position of the injection pump 31, 38 is a spill position sensor that detects the spill position, 39 is a timing control valve that controls the timer position of the injection pump 31, and 40 is a linear solenoid for controlling the spill position of the injection pump 31. A timer position sensor detects the timer position, 41 is a fuel cut valve (FCV) of the injection pump 31, 42 is a starter sensor that generates a starter operation signal, 43 is a torque converter sensor that generates a torque converter operation signal, and 44 is an air conditioner operation signal. Air conditioner sensor that generates 4
5 is a vehicle speed sensor that generates a signal corresponding to the vehicle speed, and 46 is a rotational speed sensor that is linked to the crankshaft and generates a signal corresponding to the engine rotational speed, each of which is connected to the control means 29.

The control means 29 is constituted by a microcomputer, for example, as shown in FIG.
A fixed map in which the data of the NE-TC map of the white smoke generation area determined experimentally in advance based on the data necessary for calculation processing and the engine speed and pre-combustion chamber temperature shown in Figure 4 is stored. Memory ROM4
8, a RAM 49 for temporary storage, a RAM 50 for backup that retains memory even after the key switch is turned off, and input/output ports 51 and 52, and each of the above components is interconnected by a common bus 53. Each input/output port 51, 52 and CPU
47 includes buffer circuits 54 to 62, multiplexer 63, A/D converter 64, sensor signal detection circuits 65 and 66, waveform shaping circuit 67, and drive circuits 68 to 47.
71, a D/A converter 72, a servo amplifier 73, a power supply abnormality detection circuit 74, and the above-mentioned sensors, etc., a battery 75, and an analog of the fail detection circuit.
Each is connected to the ECU 76.

Here, fuel is supplied to the pre-combustion chamber 32 by first supplying a required amount of fuel from the injection pump 31 to the injection nozzle 30 at a timing corresponding to the number of engine circuits. On the other hand, CPU
47 calculates the optimum fuel amount based on the engine rotation speed data detected by the rotation speed sensor 46, the intake air temperature detected by the intake air temperature sensor 24, the cooling water temperature detected by the water temperature sensor 35, etc. The linear solenoid 37 of the injection pump 31 corresponds to this optimum fuel amount and injection timing.
The timing control valve 39 is controlled, and the fuel injection amount and timing for the engine 11 are corrected to match the operating state of the engine 11.

In the NE-TC map of the white smoke generation area stored in the ROM 48, the coordinates (NE, TC) of points a, b, c, d, e, and f shown in the graph of FIG. 4 are (0 , 300), (1000, 400),
(2000, 480), (3000, 580), (4000, 800), and (8000, 800) are preferably defined in the area below the straight line connecting each of them from the viewpoint of effective white smoke prevention. In the example shown in Fig. 4, if the chamber temperature TC exceeds 800°C, white smoke will not be generated, and if the temperature is lower than that, the engine speed will increase as shown in a to e in Fig. 4. As the number NE increases, the chamber temperature
It is remembered as a relationship where TC also increases.

Next, the energization control of the glow plug 33 will be explained according to the flowchart of the control program shown in FIG.

As the main routine process is executed by turning on the key switch, the glow plug control process is executed regardless of whether before or after starting, and at step 101, the engine speed NE and the temperature TC of the engine pre-combustion chamber 32 are taken in, and the process continues from step 101. In step 102, the NE-TC map data shown in FIG. ) temperature TC is the fourth
Whether or not the glow plug 33 should be energized is determined based on whether or not it is within the white smoke generation area indicated by diagonal lines in the figure, that is, the white smoke generation area determined experimentally in advance. chamber) temperature
When TC is in the white smoke generation area indicated by the diagonal line in Figure 4,
If the determination is ``YES'', the process moves to step 104.
At the time of starting when the glow plug 33 is energized or kept energized to generate heat and the engine pre-combustion chamber 32 is heated, the engine 11 is easily started;
Prevent white smoke. The same process is performed during engine startup to prevent white smoke.

When the glow plug 33 is energized,
Engine speed NE and pre-combustion chamber temperature
When the white smoke generation conditions determined by TC deviate from the white smoke generation area indicated by diagonal lines in Figure 4, the process proceeds to step 1.
The determination in step 103 is "NO", and the process moves to step 105, where the energization to the glow plug 33 is cut off or the cut state is maintained. For example, in this embodiment, as shown in FIG.
Even at high speeds such as 5000rpm and 6000rpm, the temperature
It can be controlled so that electricity is applied only to areas where white smoke is generated, such as turning on electricity when the temperature is 700°C or 600°C, but not turning it on if the temperature is about 500°C even if the rotation speed is below 1000 rpm.

Therefore, unlike the conventional afterglow, which is energized for a certain period of time after startup, the glow plug 33 is energized only for the necessary and minimum effective time without waste, and the engine continues to operate even after that, as indicated by diagonal lines in Fig. 4. When the engine enters the white smoke generation region, the glow plug 33 is energized to improve the combustion condition and prevent the generation of white smoke not only during cold periods but also when the intake pressure and temperature are low. It also prevents engine noise during cold hours.

[Effects of the Invention] As described above, the diesel engine white smoke generation prevention device of the present invention includes a glow plug for heating the inside of the combustion chamber of the diesel engine, and a temperature sensor that detects the temperature inside the combustion chamber and issues a signal corresponding to the temperature. Sensor and engine speed sensor that works in conjunction with the crankshaft to detect the engine speed and emit a signal corresponding to the engine speed, and the relationship between the engine speed and the combustion chamber temperature at which the glow plug should be energized at that engine speed. A relationship is established in advance in which the temperature in the combustion chamber increases as the engine speed increases, and based on the signals from the temperature sensor and the rotation speed sensor, if the above relationship is satisfied, the glow plug is energized and the temperature is filled. Equipped with an energization control means that cuts off energization when the glow plug is not energized, it is possible to generate white smoke while minimizing energization to the glow plug without substantially increasing the production cost or weight of the vehicle. It is possible to almost certainly prevent this, and also has the effect of preventing engine noise when it is cold.

[Brief explanation of the drawing]

Fig. 1 is a diagram corresponding to claims of the present invention, Fig. 2 is a schematic diagram of an embodiment of the present invention and its surroundings, and Fig. 3 is a diagram corresponding to the claims of the present invention.
The figure is a block diagram of the same embodiment, Figure 4 is an NE-TC map corresponding to the white smoke generation state of this embodiment, and Figure 5 is a block diagram of the same embodiment.
The figure is a flowchart showing the process of energizing the glow plug 33. DESCRIPTION OF SYMBOLS 11... Diesel engine, 29... Control means, 32... Engine pre-combustion chamber, 33... Glow plug, 34... Temperature sensor, 46... Rotational speed sensor.

Claims (1)

[Scope of Claims] 1. A glow plug for heating the inside of a combustion chamber of a diesel engine; A temperature sensor that detects the temperature inside the combustion chamber and issues a signal corresponding to the temperature; and Detects the engine rotation speed in conjunction with the crankshaft. and a rotation speed sensor that emits a signal corresponding to the number of points between them. The temperature in the combustion chamber is also set to be high, and based on the signals from the temperature sensor and rotation speed sensor, if the above relationship is satisfied, the glow plug is energized, and if not, the glow plug is turned off. What is claimed is: 1. A device for preventing the generation of white smoke in a diesel engine, characterized in that it is equipped with an energization control means.