JPS6038532B2 - Combustion chamber of internal combustion engine - Google Patents

Description

[Detailed description of the invention] The present invention relates to a combustion chamber of an internal combustion engine.

Currently, a major challenge for internal combustion engines is to improve thermal efficiency while reducing harmful components in exhaust gas.

An effective method for reducing harmful components in exhaust gas is to use a lean mixture to simultaneously reduce the three components HC, CO, and NOx, and to recirculate a large amount of exhaust gas to the engine intake system to reduce NOx. Although methods are known to reduce the spread, these lean mixtures as well as mixtures containing a large amount of recirculated exhaust gas have a slow fire propagation rate and therefore a slow combustion rate to obtain a sufficiently high thermal efficiency. They have a common drawback of not being able to obtain satisfactory output as a result. Therefore, when such a combustible mixture is used, increasing the combustion rate becomes the most important issue in increasing thermal efficiency. As an internal combustion engine that can effectively increase the combustion speed of the combustible mixture in the combustion chamber, an intake gas storage chamber is provided to temporarily store a portion of the intake gas introduced into the combustion chamber from the engine intake system. The storage chamber is formed in the cylinder head and connected to the combustion chamber via an on-off valve, and the on-off valve is opened from the start of the compression stroke to the end of the compression stroke, and the intake gas stored in the storage chamber is transferred into the combustion chamber during the first half of the compression stroke. The applicant has already proposed an internal combustion engine in which a strong turbulence is generated in the combustion chamber by ejecting fuel, thereby increasing the combustion speed. However, if such a storage chamber is provided, the high-pressure stored gas will blow out during the compression stroke and the combustion chamber volume will increase, so the PV diagram will become as shown by the solid line in Figure 4, and therefore the conventional internal combustion engine shown by the broken line will Compared to the above, the loss increases by the hatched area (hereinafter referred to as storage loss).When the engine rotates at low speed or under low load when the amount of intake air is small, the air-fuel mixture in the combustion chamber is disturbed by the ejection of high-pressure stored gas. The improvement in thermal efficiency due to the increased combustion rate far exceeds the storage loss, and furthermore, this type of storage combustion method not only improves thermal efficiency, but is also extremely effective in terms of exhaust gas purification and combustion stability. It is. On the other hand, when the engine is operating at high speeds or under high load with a large amount of intake air, the air-fuel mixture in the combustion chamber is turbulent due to the inflow of intake gas or the reciprocating movement of the piston, and the effect of the turbulence caused by the ejected and stored gas is reduced. It becomes less.

In such a case, storing a large amount of stored gas will actually increase the loss. That is, it has been found that it is preferable to gradually decrease the storage chamber volume as the amount of intake air increases. SUMMARY OF THE INVENTION An object of the present invention is to provide an internal combustion engine in which the storage chamber volume is made variable to improve thermal efficiency.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIGS. 1 and 2, 1 is a cylinder block, 2 is a piston that reciprocates within a cylinder bore 3 formed in the cylinder block 1, and 4 is fixed on the cylinder block via a gasket 5. cylinder head,
Reference numeral 6 indicates a combustion chamber formed between the piston 2 and the cylinder head 4, 7 an intake valve, 8 an exhaust valve, and 9 an ignition plug.
As shown in FIG. 1, a storage chamber 10 is formed within the cylinder head 4, and a valve engagement mechanism 1 is provided at the lower end of the storage chamber 10.
An on-off valve 12 whose opening and closing are controlled by 1 is provided. On the other hand, a thin hollow cap 13 protruding into the combustion chamber 6 is fixed to the cylinder head 4 below the storage chamber 10 , and an internal chamber 14 of this cap 13 is connected to the inside of the storage chamber 10 via an on-off valve 12 . As shown in FIG. 2, a pair of entrances 15 and 16 are formed on the cap 13, and the opening 15 is directed toward the spark plug 9, while the opening 16 is directed toward the exhaust valve 8 and toward the periphery of the combustion chamber 6. be done. In this embodiment, the opening □ area of the opening □ 16 is formed to be larger than the entrance area of the closing opening 15, but the number, opening □ direction and dimensions of these openings can be variously selected depending on the engine. Figure 3 shows the intake valve 7,
The valve timing of the exhaust valve 8 and the on-off valve 12 is shown.

In FIG. 3, the vertical axis L indicates the valve lift, and the machine axis indicates the crank angle. In addition, in Fig. 3, curve A indicates the intake valve,
Curve B shows an on-off valve, and curve C shows an exhaust valve. It can be seen from FIG. 3 that the on-off valve 12 opens approximately at the start of the compression stroke and closes at the end of the compression stroke. During the intake stroke, intake valve 7
A lean mixture or a mixture containing a large amount of recirculated exhaust gas is introduced into the combustion chamber 6 via the combustion chamber 6 .

Next, when the piston 2 starts compressing the combustible air-fuel mixture in the combustion chamber 6, the on-off valve 12 opens. As will be described later, a high-pressure combustible mixture formed in the previous compression stroke is stored in the storage chamber 10, and when the on-off valve 12 is opened, this stored combustible mixture is discharged from the storage chamber 10 into the interior. room 14
It is also ejected into the combustion chamber 6 through the entrances 15 and 16.
At this time, most of the air-fuel mixture is ejected from the open row 6, and the rest is ejected from the closed port 15. As described above, since the entrance 16 is oriented toward the periphery of the combustion chamber 6, the mixture flow ejected from the entrance 16 generates a strong swirling flow in the combustion chamber 6 as indicated by the arrow K in FIG. On the other hand, the area around the electrode of the ignition plug 9 is blown away by a small amount of air mixture jetted from the entrance 15. Next, when the piston 2 rises and the pressure inside the combustion chamber 6 becomes higher than the pressure inside the storage chamber 10, the combustion chamber 6
The combustible mixture within is forced into the storage chamber 10 via the spout 15, 16 and the internal chamber 14. As the compression stroke progresses further, the pressure inside the combustion chamber 6 increases, and the storage chamber 10 increases accordingly.
The internal pressure also increases. Therefore, when the on-off valve 12 closes, a high-pressure combustible air-fuel mixture is stored in the storage chamber 10. The combustible mixture in the combustion chamber 6 is then ignited by the spark plug 9. At this time, as described above, since a strong swirling flow is generated within the combustion chamber 6, the fire rapidly spreads within the combustion chamber 6, thus increasing the combustion speed.
According to the present invention, as shown in FIG. 1, a cylindrical hole 17 constituting a part of the storage chamber 10 is formed in the cylinder head 4,
A piston cylinder device 18 is attached to the cylinder head 4 on the right side of this cylindrical hole 17 .

A movable piston 20 consisting of a large-diameter piston 20a and a small-diameter piston 20b integrally molded is inserted into the housing 19 of the piston-cylinder device 18 so as to be able to move freely. A compression spring 21 is inserted into the cylindrical hole 17.
The piston 2 is constantly pushed to the right by the spring force 1. Further, the inside of the housing 18 is divided into an atmospheric pressure chamber 22 and a pressure control chamber 23 by a large piston 20a. This pressure control chamber 23 is connected via a conduit 24 to the discharge side of an engine-driven air pump or oil pump 25 . As is well known, the discharge pressure of the pump 25 increases as the engine speed increases, and the pressure within the pressure control chamber 23 also increases accordingly. Thus, as the engine speed increases, the piston 20 moves to the left, and the capacity of the storage chamber 10 decreases accordingly. As a result, storage loss at high engine speeds can be reduced, thereby maintaining high thermal efficiency. FIG. 5 shows another embodiment of FIG.

In FIG. 5, 25 is an oil pump that always discharges a constant high pressure, 26 is an oil reservoir, 27 is a return conduit, 28 is a return oil control valve, and 29 is a control valve control circuit. On the input side of the control circuit 29, for example, an engine speed detector 30,
An intake pipe negative pressure detector 31 and an engine cooling water temperature detector 32 are connected, and the control circuit 29 controls the amount of closing of the control valve 28 based on the output signals of these detectors to change the amount of oil returned to the city. The volume of the storage chamber 10 is controlled by changing the pressure within the pressure control chamber 23. Such electronic control is advantageous because it allows the storage chamber volume to be set to be optimal in response to changes in various operating parameters such as the engine speed, but it does result in a slight increase in cost. FIG. 6 shows yet another embodiment of FIG. In FIG. 6, 25 is an air pump, and this air pump 25 is connected to the pressure control chamber 22 via a throttle 33. On the other hand, it is connected to the pressure control chamber 22 via a throttle 34 and a negative pressure conduit 35 into an intake pipe downstream of a carburetor throttle valve (not shown). Further, a compression counter 36 is provided in the pressure control chamber 22 to constantly press the piston 20 toward the left. In this embodiment, the volume of the storage chamber 10 is determined by the spring force of the two compression springs 21 and 36, the negative pressure of the intake pipe, and the discharge pressure of the air pump 25. That is, as the intake pipe member pressure decreases and the air pump discharge pressure increases, that is, as the engine load increases and the engine speed increases, the pressure within the pressure control chamber 22 increases, and the volume of the storage chamber 22 decreases accordingly. do. Considering that the intake air amount increases as the engine load increases and the engine speed increases, it can be seen that in this embodiment, as the intake air amount increases, the volume of the storage chamber 10 decreases. The present invention can be applied to an internal combustion engine having a sub-combustion chamber, and can also be applied to a compression ignition internal combustion engine.

Particularly in the latter case, the intake gas introduced into the combustion chamber consists of air or air containing recirculated exhaust gas. As described above, according to the present invention, by controlling the volume of the storage chamber depending on the operating state of the engine, it is possible to reduce storage loss and always generate optimal turbulence in the combustion chamber regardless of the operating state of the engine. In this way, thermal efficiency is increased, harmful components in exhaust gas are reduced, and stable combustion can be obtained at all times.

[Brief explanation of drawings]

Fig. 1 is a side sectional view of the engine speed according to the present invention, Fig. 2 is a bottom view of the cylinder head of Fig. 1, Fig. 3 is a graph showing the opening timing of the on-off valve, and Fig. 4 is a diagram showing the storage chamber. FIG. 5 is a side sectional view of another embodiment, and FIG. 6 is a side sectional view of still another embodiment. 6... Combustion chamber, 10... Storage chamber, 12...
...Opening/closing valve, 17... Cylindrical hole, 18...
... Piston cylinder device, 20 ... Piston, 22 ... Atmospheric pressure chamber, 23 ... Pressure control chamber, 25 ... Pump. Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1. An intake gas storage chamber is formed in the cylinder head to temporarily store a portion of the intake gas introduced into the combustion chamber from the engine intake system, and the storage chamber is stored via an on-off valve provided in the storage chamber. The chamber is connected to the combustion chamber, and the on-off valve is opened at least from the start of the compression stroke to the end of the compression stroke, so that the intake gas stored in the storage chamber is blown out into the combustion chamber during the first half of the compression stroke, and the intake gas is discharged into the combustion chamber during the second half of the compression stroke. In an internal combustion engine that sends intake gas into a storage chamber and stores it temporarily, one side wall forming the storage chamber is constructed from a movable wall member, and the movable wall member is adapted to respond to the amount of intake air. A combustion chamber for an internal combustion engine, which is connected to a drive device that moves the movable wall member as the amount of intake air increases, thereby gradually decreasing the volume of the storage chamber.