JPS6321725Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to an intake air heating device for a diesel engine.

(Prior art) Conventionally, in diesel engines, particulate matter (particulate components, mainly
Due to the requirement to reduce HC and C), a filter (adsorption member) is installed in the exhaust passage, but this poses the problem of complicating the structure and increasing cost. .

Therefore, as shown in Japanese Utility Model Application Publication No. 53-128410, for example, a supply air heating device for engine starting is provided in the intake manifold, and the supply air is heated by the supply air heating device during low load operation, thereby increasing the temperature. It has been proposed to reduce particulate matter (especially HC) by improving engine combustibility.

However, when driving at high altitudes, the air density is low,
Therefore, compared to lowlands, the increase in intake air temperature due to compression is insufficient and misfires are likely to occur, so when employing the above-mentioned device, it is necessary to perform highland correction.

(Purpose of the invention) The present invention has been made in view of the above points, and an object thereof is to provide an intake air heating device for a diesel engine that reduces particulate matter and prevents misfires when driving at high altitudes.

(Structure of the invention) The present invention provides an intake air heating means in the intake passage of the engine, and when the engine temperature is cold at a first set temperature or lower or when the outside temperature is at a low temperature at a second set temperature or lower, the intake air is heated. This relates to a diesel engine configured to operate a heating means, and includes an atmospheric pressure detection means for detecting an atmospheric pressure state, and an increase in the calorific value of the intake air heating means when the atmospheric pressure decreases, or a diesel engine configured to operate the intake air heating means. , the engine temperature is the first
The present invention is characterized by comprising an atmospheric pressure correction means that conducts electricity even in an area where the set temperature is exceeded or an area where the outside temperature exceeds the second set temperature.

As a result, the insufficient rise in intake air temperature during the compression stroke is compensated for by intake air heating, and the intake air temperature during compression increases to the self-ignition temperature. Although the air density decreases due to intake air heating, ignition is possible by increasing the temperature, as can be seen from the fact that self-ignition occurs if the intake air temperature is increased even under atmospheric pressure conditions.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

In the intake air heating device for an indirect injection type four-cylinder diesel engine shown in Fig. 1, 1 is a diesel engine, and a glow plug 4 is arranged in a combustion chamber 3 (specifically, a swirl chamber) of each cylinder 2. .

Reference numeral 5 denotes an intake passage, which includes a main intake passage 6 and a passage 4 branching from the main intake passage 6 and communicating with the combustion chamber 3 of each cylinder 2.
The main intake passage 6 has a first air heater 8 as an electric heater for heating the intake air.
However, each branch intake passage 7 is provided with a second air heater 9 as an intake air heating means. Note that the first and second air heaters 8 and 9 can be independently controlled, so that the first air heater 8
After the engine has completely exploded, it is connected in series with the glow plug 4 and serves as a dropping resistor during afterglow, and is controlled to be energized at the same time as the glow plug 4.
Afterglow occurs when the temperature of the engine coolant is below 30℃, the engine load (hereinafter referred to as mean effective pressure Pe)
) is 0Kg/cm ² or less, and the engine speed is
This is done to prevent misfires by applying approximately 6V to the glow plug 4 at 2000rpm or less.

Reference numeral 10 denotes an intake throttle valve, whose opening and closing are controlled by a diaphragm device 11. In the diaphragm device 11, the casing 11a is the diaphragm 1.
1b is divided into a first chamber 11c and a second chamber 11d, and a spring 11e is compressed in the first chamber 11c, and a negative pressure control solenoid valve 1
2 is connected to the negative pressure passage 13.
Further, the diaphragm 11b is linked to the intake throttle valve 10 via a link mechanism 11f extending toward the second chamber 11d. Therefore, the intake throttle valve 10 is
For example, in a region where the engine cooling water temperature is 30 to 60°C, the engine load is 1 kg/cm ² or less, and the engine speed is 2000 rpm or less, the intake negative pressure is controlled to increase the heating efficiency by the first and second air heaters 8 and 9. .

14 is an exhaust gas recirculation passage (hereinafter referred to as EGR passage)
The exhaust passage 15 is connected to the intake passage 5 downstream of the intake throttle valve 10. A blocking wall 1 having a large diameter hole 16 and a small diameter hole 17 is located in the middle of the EGR passage 14.
8 are provided, and first and second exhaust recirculation valves 19 and 20 open and close both holes 16 and 17 of the closing wall 18.
(hereinafter referred to as the EGR valve) is installed. Each EGR
The valves 19, 20 have casings 19a, 20a connected to first chambers 19c, 2 by diaphragms 19b, 20b.
0c and second chambers 19d and 20d;
Springs 19e and 20e are compressed in the chambers 19c and 20c, and the negative pressure control solenoid valve 2
1 and 22 are connected to the second chamber 19 of the diaphragm 19b and 20b.
Valve bodies 19g and 20g that open and close the holes 16 and 17 via rods 19f and 20f on the d and 20d sides.
are connected.

The first and second EGR valves 19 and 20, together with the intake throttle valve 10, are controlled to open and close depending on, for example, engine cooling water temperature, engine rotation speed, and engine load.

Reference numerals 25 and 26 indicate an intake pressure sensor and an intake air temperature sensor, respectively, which are disposed in the intake passage 5 downstream of the intake throttle valve 10 to detect intake pressure and intake air temperature. Reference numeral 27 indicates a water temperature sensor, which is disposed in the engine 1 and detects the engine cooling water temperature. , 28 are atmospheric pressure sensors (atmospheric pressure detection means), such as an aneroid barometer, which are turned on when the atmospheric pressure falls below a set value.

29 is a control unit that controls the operation of the engine 1, which controls the glow plug 4, the first and second glow plugs.
Air heaters 8, 9, negative pressure control solenoid valve 1
2, 21, 22, intake pressure sensor 25, intake temperature sensor 26, water temperature sensor 27, and atmospheric pressure sensor 28
are electrically linked to.

The control unit 29, as shown in FIG.
02 (atmospheric pressure correction means), and the water temperature signal, outside temperature signal, rotation signal, and load signal are input to the area determination means 101, and it is determined whether or not the area is in the intake air heating area. That is, when the engine temperature is cold, below the first set temperature, or when the outside air temperature is at a low temperature, below the second set temperature, the energization control means 102 controls the energization of the second air heater 9 as the intake air heating means. At the same time, based on the output signal from the atmospheric pressure sensor 28, if the area is at a high altitude, the heating amount of the second air heater 9 is increased in the intake air heating area at the low altitude, as shown in FIGS. 3a and 3b. The second air heater 9 is energized even in high-temperature areas other than the intake air heating area at low altitudes. In addition, Figure 3a,
In b, lines A and B are lowland,
Indicates the amount of heating at high altitudes.

Next, the control operation of the control unit 29 will be explained with reference to FIGS. 3a and 3b and FIG. 4.

First, in step _S1 , a rotation signal is input, and in step _S2 , the engine rotation speed N is changed to a set value _N0 (for example,
2000rpm) is determined, and YES
In the case of YES, the process moves to step _S3 , while in the case of NO, the process moves to step _S10 . In step _S3 , a load signal (for example, an accelerator opening signal) is input, and in step _S4 , it is determined whether or not the engine load Pe is smaller than a set value _Pe0 (for example, 1 kg/cm ² ).
If YES, proceed to step _S5 , while if NO
In this case, proceed to step _S10 . In step _S5 , a water temperature signal is input from the water temperature sensor 27, and in step _S6 , the engine cooling water temperature _T1 is changed to the set value _T01 (for example,
30° C.), and if YES, the process moves to step _S7 , while if NO, the process moves to step _S10 . In step _S7 , an outside temperature signal is input from an outside temperature sensor (not shown).
In step _S8 , the outside temperature _T2 is set to the set value _T02 (for example, 10°C).
It is determined whether or not the air heater is _smaller than
Then, in step _S11 , an atmospheric pressure signal is input from the atmospheric pressure sensor 28, and in step _S12 , it is determined whether the atmospheric pressure P is smaller than the set value _P0 (for example, if the altitude is 2000
m or more), and if YES, the amount of electricity supplied to the second air heater 9 is increased to increase the amount of heat generated in step _S13 , while if NO, the process returns to step _S1 . . On the other hand, NO in step _S8
If so, proceed to step _S10 .

Further, in step _S10 , an atmospheric pressure signal is input from the atmospheric pressure sensor 28, and in step _S14 , the atmospheric pressure P is input.
It is determined whether or not is smaller than the set value P ₀ ,
If YES, step S ₁₅ at high altitudes
The air heater 9 is turned ON, while if NO, the process returns to step _S1 .

In the above embodiment, as shown in FIG. 3a and b,
When driving at high altitudes, the calorific value of the second air heater 9, which is the intake air heating means, is increased in the intake air heating region set at low altitudes, and at low altitudes, the second air heater is energized even on the high temperature side, which is not the intake air heating region. Although the temperature is increased toward the high temperature side, it is also possible to increase only either the heat generation amount or the operating range.

Furthermore, the upper limit temperature of the intake air heating region may be set even at high altitudes.

Furthermore, in the above embodiment, the second air heater 9 is directly controlled depending on the difference between low-altitude travel and high-altitude travel, but instead, a low-altitude control map and a high-altitude control map are used. Control can also be performed by switching the map depending on whether the vehicle is running on low ground or high ground.

(Effects of the invention) Since the present invention is configured as described above, it is possible to reduce particulate matter, and since the operation of the intake air heating means is corrected for high altitudes, it is possible to prevent misfires when driving at high altitudes.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention. Figure 1 is an overall configuration diagram of a diesel engine intake air heating device, Figure 2 is a configuration diagram of a control unit, and Figures 3a and 3b are diagrams showing outside temperature and engine cooling, respectively. FIG. 4, which is a diagram showing the relationship between water temperature and heating amount, is a flowchart showing the flow of processing by the control unit. 1... Diesel engine, 5... Intake passage,
8...First air heater, 9...Second air heater,
28... Atmospheric pressure sensor, 29... Control unit.

Claims (1)

[Scope of utility model registration request] An intake air heating means is arranged in the intake passage of the engine,
In a diesel engine configured to operate the intake air heating means when the engine temperature is cold at a first set temperature or lower or when the outside temperature is at a low temperature at a second set temperature or lower, the atmospheric pressure for detecting an atmospheric pressure state is used. a detecting means; and increasing the calorific value of the intake air heating means when the atmospheric pressure drops, or detecting the intake air heating means in a region where the engine temperature exceeds the first set temperature or when the outside temperature exceeds the second set temperature. What is claimed is: 1. An intake air heating device for a diesel engine, characterized in that it is equipped with an atmospheric pressure correction means that energizes even at low temperatures.