JP3343972B2 - Combined combustion type diesel engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diesel engine comprising a combination of different types of combustion chambers.

[0002]

2. Description of the Related Art A conventional fuel injection system for a diesel engine is mostly constituted by one fuel injection pump, a fuel injection nozzle arranged for each cylinder, and an injection pipe connecting the two. . On the other hand, in some engines, a unit injector in which the injection pipe is eliminated, the injection pump and the injection nozzle are integrated, and there is no injection pipe, so that a dead volume is small and a high injection pressure can be easily generated is adopted. ing.

The unit injector is of a cam drive type in which a plunger is reciprocally driven by an engine cam to feed fuel, and a fuel having a relatively high constant pressure is stored in a common rail. The common rail type is intensified fuel supply type (common rail type) in which high pressure injection is performed by utilizing the area difference of FIG. 4 shows the common rail type unit injector 2 among them. In the injector of this type, the injection pressure is constant irrespective of the rotation speed, and since a cam for driving the injector is not required, the mounting of the engine is easier than that of the cam driven type. In the figure,
21 is a constant pressure fuel supply device, 22 is a fuel pipe, 23 is an injection nozzle, 211 is a feed pump, 212 is a common rail, 231 is a solenoid valve, 232 is a pressure increasing piston, and 233 is an injection port. (Automotive Technology Society, Automotive Technology Handbook, Design Edition, P.121, 1991)

A conventional diesel engine has a combustion chamber of a direct injection type (direct injection type, DI: Direct).
Injection) and indirect injection type (sub chamber type, ID)
I: Direct Injection). Among DI is low fuel consumption, output size, although there is Doiu advantages, large noise and vibration as disadvantages, exhaust gas amount, such as NO _X is large. IDI, on the other hand, has the advantages of low noise and low exhaust gas volume, but is not as good as the direct injection type in terms of fuel efficiency and output. However, in one conventional engine, the above-mentioned combustion chamber type is one of the above-mentioned DI or IDI, and there is no example in which a different combustion chamber type is adopted for one engine.

[0005]

In each of the combustion chamber types of the above-mentioned engines, there is a limit in improving the above-mentioned disadvantages by itself because of the structure thereof. It is difficult to always maintain good performance such as output, noise, and exhaust gas. In order to solve the above-mentioned problems, in the present invention, a single type of combustion chamber is used instead of a single type of combustion chamber. It is an object of the present invention to provide an engine that can make up for the disadvantages.

[0006]

In order to achieve the above object, according to the present invention, in a diesel engine having an even number of cylinders, an intensified fuel supply type unit injector is used, and direct injection is performed in a cylinder explosion sequence. Cylinders having a combustion chamber and cylinders having an indirect injection combustion chamber are alternately arranged, and in the high load range, the direct injection type and the indirect injection type each inject a fuel amount according to the accelerator opening and the engine speed. In the middle and low load range, the indirect injection type injects a fuel amount corresponding to the accelerator opening and the engine speed, and the direct injection type cancels out engine rotation fluctuation due to friction ( friction ). There is provided a combined combustion type diesel engine including a means for injecting fuel.

[0007]

A pressure-increasing fuel supply type unit injector (common rail type unit injector) that operates independently of each other is disposed in each cylinder having two different types of combustion chambers, a direct injection type (DI) and a sub-chamber type (IDI). Because it has
The fuel amount adapted to various operating conditions such as high speed, low speed, high load, low load, etc. is adjusted and injected for each cylinder, and the operating rate of the injector in the combustion chamber when the operating state is advantageous for each combustion chamber type And rely on the operation of other, more advantageous, combustion chamber type injectors to reduce operating rates when disadvantaged. As a result, the characteristics of each type are utilized, and the performance such as fuel efficiency, output, noise, and exhaust gas is improved as a whole.

[0008]

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an arrangement system diagram of main elements of a fuel injection system of a combined combustion type diesel engine according to the present invention. In the figure, reference numeral 10 denotes a sinter block, in which six cylinders (# 1 to # 6) are provided, among which cylinders # 1 to # 3 are provided with the DI combustion chamber 11 described above, The # 6 cylinder has an IDI combustion chamber 12. The common rail unit injector 2 is disposed in each combustion chamber, and each injection nozzle 23 of the injector communicates with a constant pressure fuel supply device 21 via a fuel pipe 22. Engine control unit (ECU) 25
Has an engine speed signal 26 and a throttle opening signal 2
7. The vehicle speed signal 28 is input, the injection timing and injection amount of each injection nozzle are determined based on this, and the output signal is sent to each injection nozzle via the conductor 29, and the engine speed at that time And fuel injection according to the throttle opening is performed. The order of cylinder explosion at this time is # 1- # 5- # 3
-In the order of # 6- # 2- # 4, DI and IDI explosions alternate.

FIG. 2 shows an engine speed (rpm) -throttle opening (Th) indicating an operation sharing area of each of the DI and IDI combustion chambers according to the operating state of the engine in this embodiment.
r) is a diagram. In the figure, region A is a region of high output traveling, which is used when starting, suddenly accelerating, traveling on a steep slope, and the like.
The region indicates a region during moderate rotation and medium load operation, which is usually most frequently used, such as during moderate acceleration, steady driving (up to around 60 km / h), and the region C is mainly used during deceleration, coasting operation, traveling downhill, etc. It is a use area. In the figure, a solid line L represents a boundary line between the region A and a region B, and a dashed line N represents a line without load.

The present system has an injection amount map for each of the DI type cylinder and the IDI type cylinder, and calculates the injection amount corresponding to the engine speed and the throttle opening separately for DI and IDI to inject. In the injection system, fuel pressurized in advance by the constant-pressure fuel supply device 21 is supplied to the injection nozzle 23, and the injection amount is adjusted according to the length of the valve opening time of the injection nozzle 23.

In the normal use range, that is, in the areas B and C of the light load and the medium load operation, the operation centering on the IDI cylinder is performed. At this time, in the DI cylinder, only the friction (friction) of the cylinder is canceled. , The discharge amount of the exhaust gas from the DI cylinder is also reduced by 20 to 30%. Therefore, at this time, the engine
The operation is performed by adjusting the injection amount in the DI cylinder.

In the region A at the time of acceleration, high load, etc.,
Both DI and IDI are operated with the respective injection amounts adjusted based on the map. At this time, DI, I
In both DI, the fuel is increased or decreased according to the throttle opening. When the throttle is fully opened, the three cylinders of DI and the three cylinders of IDI are operated at the optimum air-fuel ratio.
Higher output and lower fuel consumption than cylinders.

FIG. 3 shows a flowchart of the present system. In the figure, the engine speed and the throttle opening are checked in step 1, and when the operating state at that time belongs to the area A, the processing advances to steps 2 and 3, and when the operating state belongs to the areas B and C, the processing advances to steps 4 and 5. In step 2, the engine speed and the throttle opening indicate I
The injection quantity Q of DI is calculated, and in step 3, D
The injection quantity Q of I is calculated. In step 4, the injection amount Q of IDI is calculated in the same manner as described above, and in step 5, a constant injection amount Q for canceling the friction of the cylinder is calculated for DI. The calculated injection amount becomes an output converted to the valve opening time (injection time) of each nozzle, and a command is issued from the ECU to each unit injector to perform fuel injection in each cylinder.

As described above, in this embodiment, the combination of the constant-pressure fuel supply device and the unit injector makes it possible to set the injection amounts of IDI and DI separately, and to achieve light and medium loads (B and C). In the region (region A), an IDI-centered operation is performed, and in a high load (region A), high-output operation is performed for both DI and IDI.

[0015]

By implementing the present invention, the performance of high output and low fuel consumption, which are the advantages of DI (direct injection type), and the performance of low noise and low exhaust gas, which is the advantage of IDI (secondary chamber type), can be obtained. it is possible to obtain an engine that combines combustion Music College of conventional DI, NO _X emissions large, it is possible to compensate for the drawbacks of fuel size or the like of the IDI.

[Brief description of the drawings]

FIG. 1 is a fuel injection system layout system diagram of an embodiment of a combined combustion type diesel engine according to the present invention.

FIG. 2 is an engine speed-throttle opening degree diagram showing various load regions of the engine according to FIG. 1;

FIG. 3 is a flowchart of the fuel injection system of the embodiment.

FIG. 4 is a prior art common rail unit injector.

[Explanation of symbols]

2 ... Intensified pressure fuel supply type (common rail type) unit injector 11 ... Direct injection type (DI type) combustion chamber 12 ... Indirect injection type (IDI type) combustion chamber 21 ... Constant pressure fuel supply device 22 ... Fuel pipe 23 ... Injection nozzle 211 … Feed pump 212… common rail 231… solenoid valve 232… pressure booster piston

──────────────────────────────────────────────────続 き Continuation of front page (51) Int.Cl. ⁷ identification code FI F02M 63/00 F02M 63/00 A (58) Field surveyed (Int.Cl. ⁷ , DB name) F02D 41/02 380 F02B 75 / 20 F02D 17/02 F02M 47/00 F02M 63/00

Claims (1)

(57) [Claims] In a diesel engine having an even number of cylinders, a cylinder having a direct injection combustion chamber (11) and an indirect injection combustion are used in a cylinder explosion sequence using a booster fuel supply type unit injector (2). The cylinders having the chambers (12) are alternately arranged, and in a high load range, the direct injection combustion chamber (11) and the indirect injection combustion chamber (12) both have a fuel amount corresponding to the accelerator opening and the engine speed. was injected, in the indirect injection type combustion chamber in the low load region (12) injects an amount of fuel corresponding to the accelerator opening and the engine speed,
The direct injection type combustion chamber (11) is friction (friction)
A combined-combustion diesel engine comprising a means for injecting fuel for cancellation.