JPH09264163A - Fuel supplying device of multi-cylinder diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the deviation of heat load hysteresis between cylinders and improve the life of an engine in an engine performing a cylinder reduced operation in the operation in light load area by dividing the cylinders of the engine into resting group and operating group, and switchingly controlling the combination of cylinders constituting each group. SOLUTION: The cylinders of an in-line 6-cylinder diesel, engine in which the ignition order is set to #1-#4-#2-#6-#3-#5 are divided into first group formed of first cylinder to third cylinder and a second group formed of fourth cylinder to sixth cylinder. When a controller 20 judges that the engine is operated in light load area, the second group is designated as resting group, and the supply of fuel to the fourth cylinder to the sixth cylinder is limited to perform a cylinder reduced operation. The resting group and the operating group are switched every start or no-load operation, so that the deviation of heat load history feared between cylinders and the difference in wear of each sliding part are reduced more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply system for a multi-cylinder diesel engine, and more particularly, to limiting the supply of fuel to some cylinders during operation in a light load region where the load is smaller than a predetermined value. The present invention relates to a fuel supply device for a multi-cylinder diesel engine that improves fuel efficiency.

[0002]

2. Description of the Related Art A multi-cylinder diesel engine, in which the fuel supply to some cylinders is restricted in a light load region where the load is smaller than a predetermined value to perform reduced cylinder operation, has a high excess air ratio and pumping loss. Since it is possible to reduce the frequency of operation in a light load region where the fuel consumption is large, there is an advantage that fuel consumption and warm-up characteristics can be improved.

Focusing on such a point, in the prior art, for example, the ignition sequence is as follows: first cylinder-fourth cylinder-second cylinder-sixth cylinder-
In the case of an in-line 6-cylinder diesel engine set to the third cylinder to the fifth cylinder, the first cylinder to the third cylinder and the fourth cylinder to the sixth cylinder.
By considering the cylinders as one group and corresponding the characteristics of the injection pump to each group, the cylinder of one group is supplied with an amount of fuel according to the load and is always operated, but the cylinders of the other group are operated. In the light load region, the fuel supply was interrupted and stopped.

However, when only the cylinders of one group are constantly operated and the cylinders of the other group are deactivated in the light load region as described above, the cylinders of the always operating group are more than the cylinders of the other group. Is also overused.
Therefore, the heat load history of the cylinder head and the exhaust manifold is biased between the cylinders of both groups, or the inter-cylinder wear amount of each sliding part typified by metal, piston, piston ring, and cylinder liner. It was feared that the difference between the two would increase and the life of the engine as a whole would be greatly affected.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and is designed to perform a reduced-cylinder operation by limiting the supply of fuel to some cylinders during operation in a light load region. In a multi-cylinder diesel engine, it is an object to improve the life of the engine as a whole by reducing the bias of the heat load history that is a concern among the cylinders and the difference in the amount of wear of each sliding component.

[0006]

In order to solve the above-mentioned problems, the present invention divides the cylinders of an engine into an idle group consisting of cylinders for restricting fuel supply during operation in a light load region and an operating group consisting of the remaining cylinders. In addition, it is characterized in that a controller for switching and controlling a combination of cylinders forming each group is provided.

Further, in the present invention, it is desired that the combination of the cylinders forming each group is controlled to be switched every time the engine is started or operated without load, or at random during the operation of the engine. It is possible to supply at least an amount of fuel equivalent to no-load operation to the cylinders of the group.

Further, according to the present invention, the controller increases the supply amount of fuel to the cylinders of the operating group while restricting the supply of fuel to the cylinders of the inactive group during the operation in the light load region as the load increases. On the other hand, when operating in the high load region where the load is larger than the light load region, the fuel supply amount to the cylinders in the inactive group is increased with the increase in load while the fuel supply amount to the cylinders in the operating group is increased. It is desirable to maintain the maximum supply amount in the above, or to increase the number of cylinders that make up the operating group with an increase in load, and to randomly combine the cylinders that make up each group with the passage of time. It is preferable to change.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an embodiment of a fuel supply device for a multi-cylinder diesel engine according to the present invention, and FIG. 2 shows the fuel supply device shown in FIG. 1 in which the ignition order is first cylinder-fourth cylinder-second. Cylinder-6th cylinder-3rd cylinder-
It is a schematic side view applied to the in-line 6-cylinder diesel engine set to the 5th cylinder.

In these drawings, the fuel in the fuel tank 1 is supplied to the supply pump 5 via the pre-filter segment 2, the feed pump 3 and the fuel filter 4. Further, the common rail 7 is connected to the discharge port of the supply pump 5 via the check valve 6, and the electromagnetic injection nozzle 8 provided in the combustion chamber of the engine is connected to the common rail 7 via the flow limiter 9. A pressure-accumulation type fuel injection device is constituted by the above.

Reference numeral 10 is an electromagnetic spill valve for keeping the pressure of the common rail 7 at a predetermined value, 11 is a relief valve, 12 is a pressure limiter for preventing an abnormal increase in fuel pressure in the common rail 7, and 13 is an electromagnetic valve provided in the injection nozzle 8. A rotation sensor 1 which is a three-way valve and is provided on the crankshaft 14 of the engine.
5, the controller 2 outputs signals output from the cylinder discrimination sensor 16, the accelerator sensor 17, the pressure sensor 18 provided on the common rail 7 and the temperature sensor 19 provided on the cylinder head, or other control information represented by atmospheric pressure.
0.

The controller 20 includes a rotation sensor 15, a cylinder discrimination sensor 16, an accelerator sensor 17, and a pressure sensor 1.
8 and the signal output from the temperature sensor 19 and the like are input as control information to determine the operating state of the engine according to a program stored in advance, and based on the result of the determination, the operation of the supply pump 5 is controlled and the injection is performed. The amount and timing of fuel supplied from the nozzle 8 to the combustion chamber are optimally controlled.

Specifically, the ignition order is as follows: first cylinder # 1-fourth cylinder # 4-second cylinder # 2-sixth cylinder # 6-third cylinder #.
The cylinders of the in-line 6-cylinder diesel engine set to the third-fifth cylinder # 5 are divided into a first group including the first cylinder to the third cylinder and a second group including the fourth cylinder to the sixth cylinder. Then, when the controller 20 determines that the engine is operating in a light load region where the load is smaller than a predetermined value, the first group is designated as the operating group and the first group is designated.
While supplying fuel only to the cylinders # 1 to # 3, the second group is designated as a pause group to restrict the supply of fuel to the fourth cylinder # 4 to the sixth cylinder # 6 and reduce the engine. I am trying to operate in a cylinder. During warm-up operation in cold weather, the fuel supply to the idle group is interrupted based on the signal from the temperature sensor 19 to increase the load on the cylinders of the operating group, thereby promoting the temperature rise of the engine cooling water. At the same time, the effect of reducing white smoke can be enhanced.

Further, by designating the operating group and the rest group as described above each time the engine is started or no-load operation is performed, the deviation of the heat load history between the cylinders of both groups and the difference in the amount of wear of each sliding part are compared. However, by randomly switching the combinations of cylinders that make up each group during engine operation, there is a concern about uneven heat load history between cylinders and differences in the amount of wear of each sliding component. Can be smaller.

By the way, when the reduced cylinder operation is performed as described above, a loss occurs due to incomplete adiabatic compression to expansion of the idle cylinder. In order to reduce the loss, it is effective to open and hold the intake valve or the exhaust valve of the idle cylinder to release the compression.

In this case, however, the structure of the valve mechanism becomes complicated, which may cause problems of reliability and manufacturing cost. However, for example, as in the control patterns shown in FIGS. 3 and 4, by supplying at least an amount of fuel equivalent to no-load operation to all cylinders during engine operation, loss due to incomplete adiabatic compression to expansion of idle cylinders Can be avoided.

When the engine is operated in the cylinder cut-off manner as described above, the control pattern shown in FIG. 3 and the control pattern shown in FIG. It is possible to reduce the deviation of the heat load history due to reduced cylinder operation and the difference in the amount of wear of each sliding component, which is a concern between the two groups.However, the fuel supply form to both groups has been improved by improving the fuel supply mode to both groups. The improvement effect of can be enhanced.

That is, as shown in FIG. 3 and FIG. 4, during operation in the light load region, the fuel supply to the cylinders in the operating group is restricted while the fuel supply to the cylinders in the inactive group is limited to the equivalent amount of no-load operation. The supply amount of is increased with an increase in load. Also, when operating in the high load region, the fuel supply amount to the cylinders in the idle group is increased with increasing load, while the fuel supply amount to the cylinders in the operating group is increased to the maximum supply amount in the light load region. To hold. Then, the full operating range of the cylinders in the operating group is expanded, so that the efficiency of the engine as a whole is increased and the fuel efficiency is improved.

By the way, during operation in the light load region, the fuel consumption rate of the cylinders in the idle group is lowered because the cylinders in the idle group are supplied with fuel in an amount corresponding to no load operation. However, the amount of fuel supplied to the cylinders of the idle group in the light load region is extremely small,
Moreover, since the loss of incomplete adiabatic compression of the idle cylinders can be avoided by supplying a fuel equivalent to the no-load operation, even if the fuel efficiency of the idle cylinders decreases, the fuel efficiency of the entire engine does not deteriorate. .

In the above-described embodiment, the idle group and the operating group are simply switched every time the engine is started or no-load operation is performed, so that the deviation of the heat load history and the difference in the wear amount of each sliding part which are concerned between the cylinders are further improved. Although the number of cylinders that make up the operating group is increased as the load increases, the load on the engine as a whole is adjusted, and the combination of cylinders that make up each group is changed over time. By randomly changing all cylinders, it is possible to uniformly ignite all the cylinders, prevent the temperature of the specific cylinders from lowering, avoid an increase in friction loss, and reduce regular sounds and vibrations that are offensive to the ears.

Further, normally, when the piston reaches the vicinity of the compression top dead center, the injection nozzle 8 is operated to supply the fuel, but a part of the fuel is supplied from the beginning of the intake stroke to the middle of the compression stroke. It is possible to store in the controller 20 a program for performing a preliminary injection for injecting during intake air and a main injection for injecting the remaining fuel into the combustion chamber in the vicinity of the compression top dead center.

In this case, the fuel spray pre-injected from the injection nozzle 8 into the cylinder based on the pre-injection signal output from the controller 20 is sufficiently diffused in the cylinder due to the influence of intake air disturbance. Mixed in. Further, when the temperature of the intake air rises as the compression stroke progresses, vaporization of the fuel spray is promoted by using the intake air whose temperature has risen as a heat source, so that a lean air-fuel mixture having an equivalence ratio less than 1 is formed.

The lean air-fuel mixture thus formed is
Since it has excess oxygen and nitrogen, soot is not generated, and since the heat capacity is large, the degree of heat generation due to compression is low and it is difficult to ignite. Then, when the piston rises to the vicinity of the compression top dead center and the temperature becomes higher, a part of the lean air-fuel mixture self-ignites, but the remaining air-fuel mixture is left unburned.

When the remaining fuel is injected based on the main injection signal output from the controller 20, ignition is performed with the main injection fuel as the core. For this reason, the lean air-fuel mixture formed by the preliminary injection burns at once. However, since the lean air-fuel mixture contains excess oxygen and nitrogen, generation of black smoke and NOx is suppressed. When part of the lean air-fuel mixture ignites, the exhaust gas generated by the combustion of the lean air-fuel mixture remains in the cylinder to bring about the internal EGR effect. Generation is suppressed more reliably.

Therefore, the fuel consumption of the multi-cylinder diesel engine can be further improved by setting a program in the controller 20 for implementing the reduced cylinder operation and the fuel supply mode of the lean premixed combustion system as described above. .

[0026]

As is apparent from the above description, according to the present invention, by providing the controller for switching the combination of the cylinders forming the operating group and the cylinders forming the idle group during the reduced cylinder operation, Since the deviation of the heat load history between cylinders and the difference in the amount of wear of each sliding component, which were a concern during reduced cylinder operation, are reduced, the life of a multi-cylinder diesel engine that enables reduced cylinder operation is reduced. Can be improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a fuel supply device for a multi-cylinder diesel engine according to the present invention.

FIG. 2 shows the fuel supply device shown in FIG.
Cylinder-fourth cylinder-second cylinder-sixth cylinder-third cylinder-fifth cylinder
It is a schematic side view applied to the in-line 6-cylinder diesel engine set to the cylinder.

FIG. 3 is a schematic diagram showing an example of a control pattern of a fuel supply amount.

FIG. 4 is a schematic diagram showing another example of the control pattern of the fuel supply amount.

[Explanation of symbols]

 1 Fuel Tank 2 Pre-filter Sementor 3 Feed Pump 4 Fuel Filter 5 Supply Pump 6 Discharge Valve 7 Common Rail 8 Injection Nozzle 9 Flow Limiter 10 Electromagnetic Spill Valve 11 Relief Valve 12 Pressure Limiter 13 Electromagnetic Three-way Valve 14 Crankshaft 15 Rotation Sensor 16 Cylinder Discrimination sensor 17 Accelerator sensor 18 Pressure sensor 19 Temperature sensor 20 Controller

Claims (6)

[Claims] 1. A multi-cylinder diesel engine in which the supply of fuel to a part of cylinders is restricted to perform reduced cylinder operation during operation in a light load region where the load is smaller than a predetermined value, and the cylinders of the engine are It is characterized in that it is divided into an idle group of cylinders that restricts fuel supply during operation in the light load region and an operating group of remaining cylinders, and that a controller that controls switching of the combination of the cylinders that make up each group is provided. Fuel supply device for multi-cylinder diesel engine. 2. The multi-cylinder diesel engine according to claim 1, wherein the controller controls switching between combinations of cylinders forming each group each time the engine is started or operated under no load. Fuel supply system. 3. The fuel supply device for a multi-cylinder diesel engine according to claim 1, wherein the controller randomly controls a combination of cylinders forming each group during operation of the engine. 4. The fuel supply device for a multi-cylinder diesel engine according to claim 1, wherein the controller supplies at least an amount of fuel equivalent to no-load operation to the cylinders of the idle group. . 5. The controller increases the fuel supply amount to the cylinders of the operating group with the increase of the load while restricting the fuel supply to the cylinders of the idle group during the operation in the light load region, while When operating in a high load range where the load is larger than the load range, the fuel supply amount to the cylinders in the idle group is increased as the load increases while the fuel supply amount to the cylinders in the operating group is increased to the maximum in the light load region. It is made to hold | maintain at a supply amount, Any one of Claims 1-4 characterized by the above-mentioned.
A fuel supply device for a multi-cylinder diesel engine according to the item. 6. The controller increases the number of cylinders forming an operating group with an increase in load, and randomly changes the combination of cylinders forming each group with the lapse of time. The fuel supply system for a multi-cylinder diesel engine according to any one of claims 1 to 4.