JPH03213624A - Variable cycle diesel engine - Google Patents

Abstract

PURPOSE:To convert the 2-cycle and the 4-cycle easily by providing main and sub combustion chambers linked through a linking passage, furnishing a switching means to the linking passage, and opening and closing the switching means at every alternate compression stroke in the 4-cycle operation, while stopping the switching means in the opening condition in the 2-cycle operation. CONSTITUTION:A suction port 11 is formed at the lower side of a cylinder 1, and an exhaust port 12 is formed at the upper position of a specific amount from the position of the suction port 11. The suction port 11 is branched to a suction pipe 13 just before linking to the cylinder 1, the suction pipe 13 is opened at the upper end surface of the cylinder 1, and a suction air valve 14 is provided to the opening. A sub-combustion chamber 3 linked to a main combustion chamber 21 which is partitioned by the inner wall of the cylinder 1 and a piston 2, through a linking passage 31, is formed in a cylinder head, and an injection nozzle 33 is provided at the inside of the sub-combustion chamber 3, while a sub-chamber valve 32 is provided to the linking passage 31. And the sub-chamber valve 32 is opened and closed at every alternate compression stroke in the 4-cycle operation, while it is stopped in the opening condition in the 2-cycle operation.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention operates in two cycles when the engine is at high speed or under high load, and when the engine is at low speed and under low load, the intake air is compressed twice, substantially increasing the compression ratio and combustion. Concerning stabilizing variable cycle diesel engines.

(Prior art) In a diesel engine, when the compression ratio is lowered to achieve low compression and the intake air is supercharged to compensate for the lowered compression ratio,
It is known that the output of the diesel engine is improved.

That is, the combustion chamber pressure at the time of explosion is almost the same in both high compression ratio, low boost pressure engines and low compression ratio, high boost pressure engines.

By the way, in a low compression ratio, high boost pressure engine, by increasing the amount of fuel supplied, it is possible to increase the output. However, when the compression ratio is decreased, the theoretical thermal efficiency decreases, resulting in a worsening of the fuel efficiency.In addition, during cold start or partial load, stable combustion cannot be achieved because the temperature at the end of compression, that is, the compression end temperature, is low. do not have. Therefore, there is a limit to the reduction of the compression ratio.

(Problems to be Solved by the Invention) In such conventional low compression ratio high boost pressure engines, the compression ratio is small, so the combustion chamber temperature at the end of the compression stroke, that is, the compression end temperature, The temperature is lower than the compression end temperature of the supercharged engine.

Therefore, the problem with the low compression ratio, high boost pressure engine is that when the internal temperature of the combustion chamber is lower, such as at low speed and low load or when starting, the fuel does not ignite and combustion becomes unstable. There is.

The present invention has been made in view of the above points, and aims to provide a cycle-variable diesel engine that improves output by providing a low compression ratio and high boost pressure, and has stable combustion at low speeds and low loads. It is something to do.

(Means for Solving the Problems) According to the present invention, a sub-combustion chamber that communicates with a main combustion chamber of an engine, and a sub-combustion chamber that is provided in a communication portion between the sub-combustion chamber and the main combustion chamber, and that communicate with each other during a discrete compression stroke. an opening/closing means that closes a section to seal the intake air compressed in the auxiliary combustion chamber and opens the communicating section in another compression stroke; and the opening/closing means is operated in an open state during two-cycle operation of the engine. It is possible to provide a variable cycle diesel engine characterized in that it has a normally open means for stopping the engine.

(Function) In the cycle-variable diesel engine of the present invention, when the internal temperature of the combustion chamber is high, such as at high speeds or high loads, normal two-cycle operation is performed, and when the combustion chamber internal temperature is high, such as at low speeds and low loads, When the internal temperature is low, the compressed intake air is once sealed in the auxiliary combustion chamber, and in the next compression stroke, the auxiliary combustion chamber is opened to the main combustion chamber, and in the previous compression stroke, the auxiliary combustion chamber is opened to the main combustion chamber. The compressed intake air and the currently compressed intake air are combined to raise the compression end temperature.

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

FIG. 1 is a block diagram showing one embodiment of the present invention.

1 is a cylinder of an engine according to the present invention.

An intake boat 11 is disposed at the bottom of the cylinder 1 and communicates with the inside of the cylinder 1. In addition, the intake boat 1
An exhaust port 12 is disposed a predetermined amount above the communication position of cylinder 1, and communicates the inside of cylinder 1 with outside air.

Further, the intake boat 11 branches into an intake pipe 13 immediately before communicating with the cylinder 1. The intake pipe 13 communicates with the cylinder 1 at the upper end surface of the cylinder 1, and an intake air valve 14 is disposed at the communication port.

A valve driving device 1 is provided at the shaft end of the intake air valve 14.
5 are connected. The valve driving device 15 freely opens and closes the intake air valve 14 based on an external signal. For example, a movable permanent magnet connected to the shaft end of the intake air valve 14 is attracted and repelled by a fixed electromagnet. The configuration is as follows.

The valve driving device 15 may also be configured to move a rocker arm that connects a normal camshaft and the intake air valve 14 using hydraulic pressure to freely connect or disconnect the camshaft and the intake air valve 14. good.

The intake boat 11 is provided with a throttle valve 16 upstream of the starting point of the intake pipe 13.

The throttle valve 16 is activated by the intake boat 1 in response to an external signal.
1 and the air flow rate flowing to the intake pipe 13.

A compressor 17 is further upstream of the throttle valve 16.
is arranged to forcefully feed outside air to the throttle valve 16. The compressor 17 may be a turbocharger driven by the exhaust gas discharged from the exhaust port 12, a Roots blower mechanically driven by the rotating shaft of the engine, or another structure.

2 is a piston slidably disposed within the cylinder 1. A main combustion chamber 21 is formed by the piston 2 and the inner wall of the cylinder 1, and the intake pipe 13 communicates with the main combustion chamber 21.

The main combustion chamber 21 is further communicated with the auxiliary combustion chamber 3 through a communication passage 31 . A rotary sub-chamber valve 32 is disposed in the communication passage 31. The sub-chamber valve 32 freely opens and closes the communication port 31 in response to an external signal.

Note that the subchamber valve 32 is closed to the communication port 3 by an external signal.
It is not limited to the rotary type, as long as it can be opened and closed freely.

An injection nozzle 33 is disposed in the sub-combustion chamber 3 and injects fuel supplied from a fuel pump 34 into the sub-combustion chamber 3 . Note that the fuel pump 34 can freely change the timing of fuel supply to the injection nozzle 33 based on an external signal.

Furthermore, a temperature sensor 35 for detecting the inner wall temperature of the auxiliary combustion chamber 3 is disposed near the auxiliary combustion chamber 3 .

The temperature sensor 35 is connected to the controller 4,
The detected temperature is input to the controller 4.

In addition to the temperature sensor 35, the controller 4 receives signals from a rotation sensor 41 that detects the number of revolutions of the engine, and a load sensor 42 that detects the load on the engine.

Further, the valve driving device 15, throttle valve 16, subchamber valve 32, and fuel pump 34 are connected to the controller 4, and the controller 4 outputs control signals to these.

The controller 4 includes a human output interface that controls the input and output of the above-mentioned signals, as well as an RO that stores programs and the like in advance.
M, a CPU that performs calculations based on the program stored in the ROM, a RAM that stores calculation results and various data;
The controller 4 is composed of a control memory that controls the flow of signals inside the controller 4, and the like.

Next, the operation of this embodiment with the above configuration will be explained.

FIG. 2 is a timing chart illustrating the operation during two-stage compression.

This diagram starts from the time of explosion, and from the top of the diagram, as the crank angle advances, the stroke changes, the stroke of the piston 2, the opening/closing state of the pre-chamber valve 32, the intake air valve 1
4 is shown in the open and closed state.

When the crank angle is 0° in the figure and fuel explodes in the combustion chamber, the intake air valve 14 is closed, so the expansion stroke begins and the piston 2 is pushed down. When the upper end of the piston 2 descends to the opening position of the exhaust boat 12, the combustion gas inside the cylinder 1 is ejected from the exhaust boat 12, and the internal pressure decreases. Then, the exhaust residue remaining inside the silicator 1 is scavenged by the intake air that is force-fed from the intake boat 11 that opens subsequently.

Subsequently, the piston 2 passes through the bottom dead center (BDC), reverses upward, and enters the compression stroke I. Since the auxiliary chamber valve 32 is open during the compression stroke, compressed intake air is sent to the auxiliary combustion chamber 3.

When the piston 2 reaches the top dead center (TDC) and the compression stroke (2) ends, the auxiliary chamber valve 32 is closed to seal the compressed intake air inside the auxiliary combustion chamber 3, and the intake air valve 14 is driven to stop the intake air. The pipe 13 and the main combustion chamber 21 are communicated with each other. Then, as the piston 2 descends, intake air is drawn into the main combustion chamber 21.

Then, when the piston 2 starts rising again after passing through BDC, the intake air valve 14 is closed and the compression stroke H is started. Then, when the piston 2 rises a predetermined amount from BDC and closes the exhaust boat 12, the subchamber valve 3
2 is opened, and the air is compressed in the current compression stroke II together with the intake air compressed in the compression stroke ■.

Then, fuel is injected and exploded at TDC, and the process from the first explosion is repeated to perform the four-cycle operation.

Note that when the amount of intake air compressed by the two compression strokes exceeds 5, the amount of intake air flowing into the cylinder 1 is limited by the throttle valve 16.

Next, the details of control by the controller 4 will be explained.

FIG. 3 is a flow diagram showing the control details according to this embodiment.

In step 1, the engine rotation speed Ne from the rotation sensor 41, the engine load Le from the load sensors 4 and 2,
The sub-combustion chamber wall temperature Tw from the temperature sensor 35 is measured manually.

Then, in steps 2 to 4, the Ne, Le,
Tw is compared with the corresponding predetermined values No, Lo, and TO, and if both are below the predetermined value, the process proceeds to step 5, and if at least one measured value is greater than or equal to the predetermined value, the process proceeds to step 8.

In step 5, a signal is output to the fuel pump 34 to set the fuel injection timing to the timing corresponding to the four-cycle operation explained in FIG.

Then, in step 6 and step 7, the pre-chamber pulp 3
2 and the intake valve 14 are operated at the timing shown in FIG.

On the other hand, if you proceed to step 8, set the fuel injection timing to the normal 2-cycle operation timing,
In step 9, the subchamber valve 32 is normally opened and the communication passage 31 is opened.
are in constant communication.

Further, in step 10, the signal output to the valve driving device 15 is stopped, and the intake air valve 14 is brought into a normally closed state. As described above, the flow to step 8 is a flow for performing a normal two-cycle operation.

Incidentally, although this embodiment has been described using a cross-scavenging two-stroke engine, a loop scavenging or uniflow scavenging two-stroke engine may also be used.

Although the embodiments of the present invention have been described in detail above, it is understood that various different embodiments can be easily constructed without departing from the spirit of the invention, and therefore, the present invention is not limited to the limitations set forth in the claims. , and is not limited to any particular implementation.

(Effects of the Invention) As explained above, according to the present invention, when the internal temperature of the combustion chamber is high, such as during high rotation or high load, the normal two-cycle operation is performed, and when the combustion chamber is operated at low speed and low load, the normal two-cycle operation is performed. If the internal temperature of the combustion chamber is low, such as in A cycle-variable diesel engine that combines the intake air compressed in the compression stroke with the intake air compressed this time to raise the compression end temperature, resulting in improved output and stable combustion at low speeds and low loads. can be provided.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a timing chart explaining the operation during two-stage compression.
FIG. 3 is a flow diagram showing the control details according to this embodiment. DESCRIPTION OF SYMBOLS 1... Cylinder, 2... Piston, 3... Sub-combustion chamber, 4... Controller, 14... Intake air valve, 16... Throttle valve, 32... Sub-chamber pulp, 34・・・
·Fuel pump. 35... Temperature sensor, 41... Rotation sensor, 42... Load sensor.

Claims (3)

[Claims] (1) A sub-combustion chamber that communicates with the main combustion chamber of the engine, and intake air that is provided in a communication section between the sub-combustion chamber and the main combustion chamber, and that is compressed into the sub-combustion chamber by closing the communication section during a separate compression stroke. and a normally open means for stopping the operation of the opening and closing means in the open state during two-cycle operation of the engine. Variable cycle diesel engine. (2) The invention further comprises a temperature detection means for detecting the inner wall temperature of the auxiliary combustion chamber, and a control means for operating the opening/closing means when the inner wall temperature is below a predetermined value.
1) Variable cycle diesel engine as described. (3) Claim (1) characterized in that the intake air compressed in the other interval compression stroke is taken in when the piston descends.
Variable cycle diesel engine as described.