JPS6318131A - Five-cycle diesel engine - Google Patents

Abstract

PURPOSE:To prevent incurring of an engine output loss due to residual combustion gas, by a method wherein, in addition to convention 4-stroke movement, a forced scavenging stroke, wherein pressurized air being high enough to allow exhaust of residual combustion gas is injected in a cylinder, is provided. CONSTITUTION:During running of an engine, a suction valve 4 is opened along with lowering of a piston 2 to suck air in a cylinder 1. With the suction valve 4 closed in a process of rising the piston 2 to compress air. Slightly before a top dead center positioned at a point of time when a compression stroke is completed, fuel is injected through a fuel injection nozzle 7, and is burnt by self-ignition. The combustion causes forced lowering of the piston 2 to effect its work, and a subsequent rising stroke of the piston 2 causes opening of an exhaust valve 6 to exhaust combustion gas. In the rear half part of an exhaust stroke, when the piston 2 approaches a top dead center, the suction valve 4 is opened, a pressurized air from a compressor 9 is fed in a cylinder 1 to forcibly exhaust residual combustion gas.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a five-stroke diesel engine used as an automobile engine.

(Prior Art) As a conventional diesel engine, for example, one described in "Automotive Engineering Complete Book Volume 5 Diesel Engine" (published by Kazu Sankaido in 1980) is known.

Among these conventional diesel engines, the 4-cycle diesel engine, which is also common and is currently in wide use, performs four strokes during two revolutions of the engine: intake stroke → compression stroke → explosion stroke → exhaust stroke. It's an engine.

The expanded combustion gas after the explosion is mainly exhausted from the exhaust hole due to the exhaust action caused by the opening of the exhaust valve and the rising of the piston. Later, when the intake valve is opened, the combustion gas is scavenged from the intake hole by the natural scavenging effect generated by the difference between the pressure in the cylinder space and the atmospheric pressure.

(The problem to be solved by the invention) However, in such a conventional four-stroke diesel engine, when the pressure in the cylinder space becomes equal to the atmospheric pressure, the natural scavenging action ends, and scavenging is not performed sufficiently. Therefore, combustion gas remains in the cylinder redder space, and due to this residual combustion gas, the intake air in the next intake stroke and the injected fuel in the next compression stroke are reduced by the amount of residual combustion gas, and the engine output is reduced. There was a problem in that it decreased by a minute.

As shown in Figure 3, the cylinder space volume Vυ (also called combustion chamber volume) at top dead center is: ■ V υ = V T X − ε VT; Cylinder space volume when the piston reaches bottom dead center The total volume ε is the compression ratio, and the effective intake volume of air, IVA (also called stroke volume), is VA=VT−Vυ.

Particularly in engines where equipment with high gas passage resistance (exhaust resistance) is installed in the exhaust system, such as a converter or muffler, residual combustion gas cannot be sufficiently exhausted due to the influence of the exhaust resistance. Its density also increases, and a large amount of combustion gas remains. For this reason, exhaust system mufflers and converters are designed to have as low resistance as possible.
Even so, there is a limit to reducing the resistance value, and for this reason, for example, in an automobile engine, the loss of engine output due to residual combustion gas reaches from a few percent to more than ten percent of the engine output.

In other words, the exhaust resistance directly affects the loss of engine output, leading to problems such as those described below.

(b) Exhaust system mufflers combine various silencing principles to reduce exhaust noise, but there is a strong correlation between the degree of noise reduction and exhaust resistance for any muffler, and generally A muffler with high resistance produces low exhaust noise. Moreover, in recent years, due to noise pollution, there has been a demand for cars with even quieter exhaust noise, so exhaust resistance tends to increase.
The aforementioned loss of engine output due to residual combustion gas increases as exhaust resistance increases.

(b) In engine heat accounting, 3 of the injected energy
Around 0% is discarded into the exhaust. Therefore, recovering and effectively utilizing this exhaust energy is very significant from the perspective of energy saving.

Therefore, it is possible to install an exhaust gas turbine or the like in the exhaust system to recover heat, but either method increases exhaust resistance and leads to a loss of engine output. This results in a loss of engine output that is greater than the recovered energy, making it difficult in practice to recover exhaust energy.

In addition, as a conventional automobile engine, for example, the above-mentioned “
A turbocharged diesel engine equipped with a turbocharger is known, as described in "Automotive Engineering Complete Book Volume 5 Diesel Engine".

This turbocharged diesel engine uses exhaust gas to rotate a turbine, and uses a compressor coaxially attached to this turbine to increase intake pressure, increasing engine output, especially in high-speed rotation ranges. .

However, this turbocharged diesel engine aims to increase diesel engine output by increasing the amount of intake air, and the loss of diesel engine output due to residual combustion gas as described above is exactly the same, and this loss is due to exhaust gas. The presence of a turbine in the system increases exhaust resistance, and in this respect the loss of diesel engine power due to residual combustion gases is greater than in a diesel engine without a turbocharger.

(Means for Solving the Problems) The present invention solves the above-mentioned problems, that is, eliminates the loss of diesel engine output due to residual combustion gas, and eliminates the influence of exhaust resistance on output. In order to achieve this objective, the present invention provides an intake hole, an intake valve, an exhaust hole, an exhaust valve, and a fuel injection nozzle in a diesel engine having the intake hole and intake valve. ′ provided in the system
1! The S feeder adds a forced scavenging stroke that injects enough pressurized air into the cylinder from the intake port to exhaust residual combustion gas when the exhaust valve is opened, and during two rotations of the engine, the intake stroke → compression Five strokes were performed in the order of stroke → explosion stroke → exhaust stroke → forced scavenging stroke.

(Function) Therefore, in the 5-cycle diesel engine of the present invention,
By using the above method, pressurized air from the supercharger installed in the intake system is injected into the cylinder following the exhaust stroke in which the exhaust valve opens and the piston rises to exhaust combustion gas. As a result, a forced scavenging stroke is performed in which the residual combustion gas is forcibly discharged to the outside, and pressurized air remains in the cylinder space at the top dead center of the piston instead of the residual combustion gas. The total volume becomes the effective air intake volume, and it is possible to eliminate loss of diesel engine output due to residual combustion gas.

Further, as described above, by exhausting the residual combustion gas to the outside by forced scavenging, it is possible to eliminate the direct influence of exhaust resistance on the engine output.

In addition, one forced scavenging stroke can be added by simply changing the camshaft that drives the intake system to a structure that allows the intake valve to open even when the exhaust valve is open, so by using this structure, a diesel engine without loss of engine output can be produced at a low cost. can be obtained.

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

In describing this embodiment, a five-stroke diesel engine used as an automobile engine will be taken as an example.

First, the configuration of the embodiment will be explained.

As shown in FIGS. 1 and 2, the 5-cycle diesel engine A of the embodiment includes a cylinder 1, a piston 2, an intake pipe 3, an intake valve 4, an exhaust pipe 5, an exhaust valve 6, a fuel injection nozzle 7, and an exhaust pipe. Gas turbine 8, near compressor (supercharger)
The main structure is 9.

The cylinder 1 is a cylindrical cylinder formed in a cylinder block, and when it has a plurality of cylinders, the cylinder arrangement is L-shaped (in-line type).

■ type, opposed piston type, etc.

The piston 2 is provided within the cylinder 1 so as to be able to reciprocate, and as shown in FIG. 1, the piston 2 is connected to a crankshaft 12 via a connecting rod 10 and a crank arm 11.

The intake pipe 3 is a pipe into which air is sucked, and the intake hole 13 of the intake pipe 3 is connected to the cylinder head portion 1 of the cylinder 1.
A is opened at the intake hole 13, and an intake valve 4 is provided at the position of the intake hole 13, which opens and closes in accordance with rotation of the camshaft.

The exhaust pipe 5 is a pipe for discharging combustion gas after explosive combustion to the outside, and the exhaust hole 15 of the exhaust pipe 5 is connected to the cylinder 1.
An exhaust valve 6 is provided at the exhaust hole 15, which opens and closes in accordance with rotation of the camshaft.

Note that this exhaust pipe 5 has a bypass pipe for excess exhaust gas, a bypass pipe for removing excess exhaust gas, and a bypass pipe for removing excess exhaust gas.
An exhaust gas turbine 8 is provided in the middle of the exhaust pipe 5, and a normally closed bypass valve 55 connected to the valve actuator 53 is provided in the bypass exhaust pipe 25. It is being

The exhaust gas turbine 8 is an exhaust energy collecting means that rotates upon receiving exhaust gas energy from the exhaust pipe 5.
The tip of the turbine shirt 20 of the exhaust gas turbine 8 projects and extends to the intake pipe 3, and a near compressor (turbo blower) 9 is attached to the tip.

In the figure, 20a is a bearing housing, and 20b is a bearing.

The fuel injection nozzle 7 is a tube that injects fuel fed under pressure from the fuel injection pump 16 into the cylinder 1, and is opened in the cylinder head portion 1a of the cylinder 1.

The near compressor 9 is a compressor that uses exhaust gas energy recovered by the exhaust gas turbine 8 to generate pressurized air for forced scavenging of combustion gas in the cylinder 1, and protrudes into the intake pipe 3. It is provided at the tip of the extended turbine shaft 20.

Next, the operation of the embodiment will be explained for each step with reference to FIG.

(a) Intake stroke e″→I I/ When the intake valve 4 opens, the piston 2 descends from the top dead center a′, and air is sucked into the cylinder 1 through the intake hole 13.

Incidentally, the exhaust hole 15 closes at e'' immediately after descending from the top dead center a'.

In this intake stroke, after the piston 2 reaches the bottom dead center b',
The process ends when the intake valve 4 closes (I").

(b) Compression Stroke I"→a" Next, the piston 2 rises from the bottom dead center b'. At this time, the exhaust valve 6 is closed, and the intake valve 4 is closed at the point where the air is compressed and its temperature and pressure rise.

(C) Explosion stroke B+e' A little before the top dead center (point A) on the compression stroke path, fuel is injected from the fuel injection nozzle 7 into the cylinder 1, and the fuel becomes a spray inside the high temperature and high pressure cylinder 1. It disperses, receives heat from the surrounding high-temperature air, and evaporates. It mixes with air to form a combustible mixture layer, and when that layer reaches a sufficiently high temperature, it spontaneously ignites and burns (point B).

Immediately after reaching the top dead center a'', the high-pressure gas generated by combustion reaches its maximum pressure (point D), and then pushes the piston 2 downward to perform work.

The shape of the combustion chamber in the cylinder 1 is designed to improve the atomization and dispersibility of the fuel that becomes the spray, thereby increasing combustion efficiency.
Although various measures have been taken, in this embodiment, as shown in FIG. 1, a part of the combustion chamber 17 is formed by recessing the upper end of the piston 2.

(d) Exhaust stroke e' → process' In the next upward stroke of the piston 2, the exhaust valve 6 opens slightly before bottom dead center b (point e'), and the expanded high-temperature and high-pressure combustion gas flows into the exhaust pipe. 5.

This discharged combustion gas becomes exhaust gas through the exhaust pipe 5.
During the process, part of the thermal energy and pressure energy of the exhaust gas rotates the exhaust gas turbine 8, and then the exhaust gas passes through the converter 35 and the muffler 45 and is discharged to the atmosphere.

In addition, in the exhaust gas energy recovery action by the exhaust gas turbine 8, by controlling the opening degree of the bypass valve 55 using the valve actuator 53 as a driving part, an excessive amount of exhaust gas is diverted to the bypass exhaust pipe 25. The pressure of the exhaust gas fed into the exhaust gas turbine 8 is maintained so as not to exceed a set pressure.

(e) Forced scavenging effect '→e' In the latter half of the exhaust stroke of the piston 2, when the piston 2 approaches top dead center, the intake valve 4 opens (point I') and rotates coaxially with the exhaust gas turbine 8. The pressurized air from the near compressor 9 flows from the intake hole 13 into the cylinder 1.
This forced scavenging stroke ends when the exhaust valve 6 closes (point e'') and the residual combustion gas is forcibly discharged to the outside.

In addition, the dotted line in FIG. 2 shows a PV diagram when the engine is not provided with a supercharger, and Po shows atmospheric pressure.

The amount of pressurized air in this forced scavenging stroke increases according to the rotation speed of the exhaust gas turbine 8, so as the engine speeds up and the scavenging time becomes shorter, the pressure and flow rate of the pressurized air decrease. A stable scavenging action can be obtained without controlling the pressurized air, and since it starts before the top dead center of the piston 2, there is no time lag and a high forced scavenging effect can be expected.

In addition, due to the forced scavenging stroke, the effective air intake capacity becomes the cylinder's total volume, and pressurized air remains in place of residual combustion gas during the intake stroke, so the amount of fuel supplied is larger than before, and the cylinder It is necessary to adjust the fuel supply system so that the mixture has the same concentration as before when mixed with pressurized air in 1, and the amount of fuel is approximately (1+-)
It can be doubled.

As explained above, in the five-stroke diesel engine A of the embodiment, residual combustion gas is forcibly discharged to the outside by pressurized air from the near compressor 9 driven by the exhaust gas turbine 8 when the exhaust valve 6 is opened. In other words, forced scavenging is performed, so there is no loss of engine output due to residual combustion gas, and as a result, the engine output can be increased.

In addition, most of the residual combustion gas is exhausted to the outside through forced scavenging, which eliminates the direct effect of exhaust resistance on engine output, which greatly increases the degree of freedom in designing the exhaust system. A near compressor 9 driven by an exhaust gas turbine 8 is installed in the exhaust system of this engine.
Even if the engine is added, there is almost no reduction in engine output, and the engine can effectively utilize exhaust gas energy.

In addition, as mentioned above, the degree of freedom in designing the exhaust system is greatly increased, so in addition to the exhaust gas turbine 8, it is also possible to proactively add exhaust noise reduction devices and exhaust gas energy recovery devices for other purposes. be able to.

In addition, unlike gasoline engines, diesel engines do not use a mixture, but only air is sent through the intake hole 13, so in order to perform forced scavenging, a separate forced scavenging hole or valve is added. This can be achieved by opening the intake valve 4 which also serves as a forced scavenging valve at the end of the exhaust stroke when the exhaust valve 6 is open, which is simple in structure and can be easily applied to existing diesel engines.

Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention may be modified without departing from the gist of the present invention. included.

Further, in the embodiment, the near compressor is preferably driven by an exhaust gas turbine, but may be driven by an engine or an electric motor.

Furthermore, the shape of the combustion chamber within the cylinder is not limited to the embodiment.

Furthermore, in the embodiment, even when the exhaust valve is closed and the intake valve is open, the supercharging continues, so of course a supercharging effect can be expected.

(Effects of the invention) A supercharger is installed in the intake system, and a forced scavenging stroke is added to inject enough pressurized air into the cylinder to exhaust residual combustion gas when the exhaust valve is opened. In addition, five strokes are performed in the order of intake stroke → compression stroke → explosion stroke → exhaust stroke → forced scavenging stroke, so residual combustion gas is forcedly scavenged, eliminating loss of diesel engine output due to residual combustion gas, This provides the effect of increasing engine output.

In addition, most of the residual combustion gas is exhausted to the outside through forced scavenging, which eliminates the direct effect of exhaust resistance on engine output, greatly increasing the degree of freedom in designing the exhaust system. However, it is possible to proactively add an exhaust noise reduction device, an exhaust gas energy recovery device, etc. without worrying too much about an increase in exhaust resistance.

In addition, the camshaft that drives the intake system is structured so that the intake valve opens so that pressurized air is injected into the cylinder by the supercharger even when the exhaust valve is opened, and a forced scavenging stroke is added, resulting in a loss of engine output. It is possible to obtain a diesel engine without oxidation at low cost.

[Brief explanation of the drawing]

FIG. 1 is an overall view showing the intake and exhaust air passages of a five-cycle diesel engine according to an embodiment of the present invention, FIG. 2 is a P-V diagram of the embodiment engine, and FIG. 3 is an explanatory diagram of the cylinder volume of the diesel engine. A...5-cycle diesel engine...Cylinder 4...Intake valve 6...Exhaust valve 7...Fuel injection nozzle 9...Near compressor (J St, m) 13...
...Intake hole 15...Exhaust hole Figure 2 - FiV -

Claims (1)

[Claims] 1) In a diesel engine equipped with an intake hole, an intake valve and an exhaust hole, an exhaust valve and a fuel injection nozzle, a supercharger installed in an intake system having the intake hole and intake valve,
Adding a forced scavenging stroke that injects enough pressurized air into the cylinder from the intake port to exhaust residual combustion gas when the exhaust valve is opened, the engine completes two revolutions during the intake stroke → compression stroke → explosion stroke → A 5-cycle diesel engine characterized by performing five strokes in the order of exhaust stroke → forced scavenging stroke.