JPS5847112A - Two-cycle internal combustion engine - Google Patents

Abstract

PURPOSE:To provide free degrees on the operation of an admission valve and make scavinging efficiency more favorable in such a way that the valve body of the admission valve is formed by being integrally combined with a differential pressure piston, in an engine which scavenges residual exhaust air in the cylinder by a piston pump. CONSTITUTION:When a pre-pump 601 closes a suction port 23, and it comes into its compression stroke, admission pressure P1 in an admission port 701 climbs, and when an exhaust port 27 is opened, inner pressure P2 gets suddenly near to the atmospheric pressure. Therefore, the admission pressure P1 is enlarged, force-F1 in the valve opening direction which is produced from the pressure difference according to P1-P2 is applied to a valve body 16, and force-F2 in the valve opening direction which is produced from the pressure difference according to P1-Po applied thereto. In consequence, when component of force-F1 and -F2 grows larger than force F in the valve closing direction of a valve spring 19, an admission valve 151 is operated in the valve opening direction. After the exhaust port 27 has been opened, when the admission port 701 is opened, new mixed air is fed under pressure through the admission port 701 into a cylinder 501, and the mixed air pushes out residual exhaust gas to the side of the exhaust port 27 and scavenges it. In the meantime, the cylinder 501 and the port 701 are interrupted.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to improvements in two-stroke internal combustion engines used in automobiles, aircraft, and the like.

Two-stroke engines are simple in structure and operation, so they are light in weight and easy to handle. However, if the scavenging operation is not complete, residual exhaust gas will inhibit the next combustion. Furthermore, since new mixed gas is supplied into the cylinder and exhaust gas is discharged at the same time, part of the mixed gas escapes from the exhaust port, causing so-called blow-by, which increases fuel consumption and
The disadvantage is that it costs more. The present applicant previously disclosed in Japanese Patent Application No. 51-155858 a two-stroke internal combustion engine that can eliminate the drawbacks of the two-stroke engine. The 2-size, 2-ru internal combustion engine uses a piston-type pump driven by a crankshaft to scavenge residual exhaust gas in the combustion cylinder with a mixed gas pressurized by the piston-type pump.

This effectively scavenges the air inside the combustion cylinder,
In particular, the exhaust gas around the spark plug at the top of the combustion cylinder is blown away and surrounded by a completely new air-fuel mixture, resulting in excellent ignition and combustibility. However, in such engines, the intake valve opens only when the force in the valve opening direction due to the pressure difference between the combustion cylinder side and the intake boat side exceeds the valve closing force due to the pulp spring. However, there is a disadvantage that the valve opening period and the amount of opening of the valve are relatively limited.

It is an object of the present invention to provide a two-stroke internal combustion engine that allows relatively more freedom in the operation of an intake valve and has better air scavenging performance.

The two-stroke internal combustion engine according to the present invention is driven by a crankshaft, and includes a piston-type pump that pressurizes the air-fuel mixture from the air-fuel mixture intake system and pumps it into the combustion cylinder through the air intake port, and an air intake boat that connects the engine intermittently. The air supply valve is equipped with a piston type pump to scavenge residual exhaust gas in the combustion cylinder, and the air supply valve is equipped with a pressure difference between the combustion cylinder side and the air supply boat side, which generates a force in the valve opening direction. It is formed by integrally connecting the valve body that receives the air pressure, and the differential pressure biston that receives the force in the valve opening direction due to the pressure difference between the atmosphere and the air supply boat side. Therefore, the air supply valve receives an additional force in the valve opening direction from the differential pressure piston, and this differential pressure piston acts as a booster. In other words, by changing the shape of the differential pressure piston, the valve opening period and valve opening amount of the intake valve can be adjusted, and the timing and amount of air-fuel mixture supplied into the combustion cylinder can be set to desired values. It can contribute to increase in output.

The present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a two-stroke internal combustion engine (hereinafter simply referred to as engine) 1 as an embodiment of the present invention. This engine 1 is for an automobile, and is a water-cooled inline four-cylinder type with the left side in FIG. 1 facing forward. The engine 1 has a cylinder block 2 in the center, a seven-ring head 3 above the cylinder block, and an oil pan 4 below the cylinder block 2, which are integrally fixed. Inside the cylinder block 2, four cylinders 5 are arranged in a row in the front-rear direction.
The second cylinders 501 and 502 and the rear third and fourth cylinders 503 and 504 are each provided with two piston-type pumps 6 (the rear pumps are not shown) that supply the air-fuel mixture. (See Figure 2). That is, the discharge side of the front piston type pump (hereinafter simply referred to as the front pump) 601 has two channels, one of which is connected to the first cylinder 501.
The other side communicates with the air supply port 701 of the second cylinder 502, and the other side communicates with the air supply port 702 of the second cylinder 502. Similarly, one side of the discharge side of a rear piston type pump (hereinafter simply referred to as the rear pump), which is not shown, communicates with the air supply port of the third cylinder 503, and the other side communicates with the air supply port of the fourth cylinder 504, respectively.

As shown in FIG. 2, both pumps use a chain drive system consisting of a sprocket 9 on the crankshaft 8 side, a sprocket 10 on the pump side, and a chain 11 connecting these. The cylinders 501 and 502 communicate with each other through a communication hole 12 at the cylinder head 3 portion, and both pistons 1
31. The operation timing of 132 is also the same. Similarly, the third and fourth cylinders 503 and 504 also have communication holes 14
The actuation timing of both pistons 133 and 134 is also the same.

Engine 1 is a 4-cylinder engine as described above, but looking at its operation, it appears to be an in-line 2-cylinder engine.
The third and fourth cylinders 503-, 504 on the rear side are configured to be shifted by 180 degrees in rank angle with respect to the second cylinders 501 and 502. Therefore, in the following description, the first cylinder 501 and the piston 13 inserted therein will be described.
Is 1 the same as the cylinder and piston of a conventional 2-cycle engine? Inhalation, compression, explosion,
Complete each action of exhaust. This first cylinder 501 has an air supply port 701 arranged on the cylinder head 3 side,
The air supply port 701 and the inside of the first cylinder 501 are operated intermittently by the air supply valve 151. This air supply valve 151 includes a valve main body 16 that functions as a check valve, a stem 17 extending from this, a differential pressure piston 18 that is integrally connected to the tip of the stem 17, and a valve main body 16 side. The valve spring 19 applies a force F in the valve closing direction. The differential pressure piston 18 is inserted into a differential pressure cylinder 20 that is integrally formed on the cylinder head 3 side. An air passage 201 is connected to one space of the differential pressure cylinder 20 so that the air supply pressure P1 of the air supply port 701 is applied thereto (see FIG. 2), and an opening 202 is formed in the other space. Opened to the atmosphere.

Front pump 6 with discharge port 21 communicating with air supply hole 1701
01 has a suction port 23 on the side wall surface of the pump cylinder 22,
The intake port 23 is connected to a carburetor 24 on the side of the air-fuel mixture intake system. The piston 25 of this pump 601 is moved up and down by the crankshaft 26 to open the suction port 23 at 65 degrees before the bottom dead center (see FIG. 3).

An exhaust hole 27 is formed in the bottom of the first cylinder 501, and exhaust gas from the cylinder is discharged from the exhaust hole 27 to the outside through an exhaust pipe 28 (see FIG. 2).

A water jacket 29 through which cooling water flows is formed in the rotor of the first cylinder 501, and is connected to a cooling system including a water pump 30. In addition, the engine 1 is provided with usual auxiliary mechanisms such as an ignition system and a lubrication system.

The operation of the engine 1 shown in FIG. 1 will be explained.

First, as shown in FIG. 3, the intake port 23 of the front pump 601 opens at a crank angle of 65 degrees before the bottom dead center of the pump, and sucks the air-fuel mixture up to 65 degrees after passing the bottom dead center. At this time, the piston 131 in the first cylinder 501 performs an explosive expansion stroke from the top dead center. That is, the piston 25 of the front pump always rotates 115 degrees earlier than the piston 131 of the first cylinder, and the crankshaft 8 of the first cylinder and the crankshaft 26 of the front pump rotate at the same angular velocity. Rotate in the same direction.

In the position shown in FIG. 3, the front pump 601 is just before suction and exhibits the largest negative pressure, so the supply pressure P1 of the air supply port 701 also becomes negative pressure. On the other hand, the pressure P2 inside the first cylinder 501 shows the largest positive pressure due to the explosion of the air-fuel mixture ignited by the plug 31. At this time, the air supply valve 151 receives a force F1 in the valve closing direction generated from the pressure difference between P2 and PI on the valve body 16, and an air supply pressure P1 that is lower than the atmospheric pressure PO applied to the differential pressure piston 18. The force F2 generated in the valve closing direction and the force F of the valve spring 19 are added (the air supply port)
701 is completely blocked. As shown in FIG. 4, when the intake port 23 of the front pump 601 opens, the air supply port 701 side approaches atmospheric pressure, and the force F2 due to the differential pressure is no longer applied to the differential pressure piston 18 of the air intake valve 151, and the valve Air supply port 70 due to force F1 applied to main body 16 and force F of valve spring 19
1 is cut off from the inside of the first cylinder 501.

As shown in FIG. 5, the front pump 601 is at -65
When the temperature exceeds 0.degree., the suction port 23 is closed, a compression stroke begins, and the supply pressure P1 of the supply air port 701 increases. On the other hand, while the piston 131 is between 65 degrees before the bottom dead center and 65 degrees after the bottom dead center, the first cylinder 501 opens its exhaust hole 27, so the internal pressure P2 rapidly approaches atmospheric pressure.

Therefore, the air supply pressure PI at the air supply port becomes larger than P2, which is close to atmospheric pressure, and a force F1 in the valve opening direction generated from the pressure difference due to PI - P2 is applied to the valve body 16, and the differential pressure piston 18 Addition of atmospheric pressure and supply pressure P1, Pi
-Car F2 in the valve opening direction caused by the pressure difference due to PO
is added. Therefore, the resultant force of -Fl and -F2 is the valve spring 19
When the force F in the valve closing direction is reduced, the air supply valve 15
1 operates in the valve opening direction. In this case, the differential pressure piston 18
The car F2 that is received by the air is generated at the same time that the air supply port 701 becomes positive pressure. Therefore, by changing the size of the differential pressure piston I8.

It becomes easy to adjust the car F2 to communicate with the inside of the first cylinder 501 and the air supply port 701 at a desired time. After opening the exhaust hole 27, the air supply bow)
701 is opened, a new air-fuel mixture (from the air supply port 701) is forced into the first cylinder 501, and this air-fuel mixture flows from the cylinder head 3 side to the exhaust hole 27 side, exhausting residual exhaust gas. The air is pushed out to the hole 27 side for scavenging. During this time, the air supply valve 151 remains open, but just before the exhaust hole 27 of the first cylinder is closed, the force F of the valve spring acts to open the first cylinder.
The inside of the cylinder and the air supply port 701 are shut off. The annular space 32 formed in a part of the joint between the first cylinder 501 and the cylinder head 3 is for reversing the inflow direction of the air-fuel mixture passing through the air supply valve 151. The air-fuel mixture can flow uniformly within one cylinder 501, and mixing of this with residual exhaust gas can be prevented, and fresh air can also be prevented from blowing through. Furthermore, the communication hole 12 (first
(see figure) has high ignition reliability because the other side works to ignite the first or second slit. ' As shown in FIG. 6, the front pump 601 reaches top dead center,
After passing through this, the supply pressure P1 of the air supply port 701 becomes a negative pressure and decreases. On the other hand, the pressure P2 inside the first cylinder 501 increases because the piston 131 closes the exhaust hole 27 and is in the compression stroke. At this time, the valve body 16 of the air supply valve 151
A differential pressure between positive pressure F2 and negative pressure Pl is applied to the valve, a force F1 acts in the valve closing direction, and a differential pressure between atmospheric pressure PO and negative pressure Pl acts on the differential pressure piston 18. is applied, and a force F2 acts in the valve closing direction.

Therefore, the first cylinder 501 is compressed in a sealed state, and the piston 25 of the front pump 601 works in a sealed state, expanding the volume inside the pump cylinder 22 to 65 degrees before bottom dead center, and expanding the negative pressure of the supply pressure PI. do. Thereafter, the state shown in FIG. 3 is returned to complete one stroke of the two-stroke engine.

In the above-mentioned place, when scavenging the residual exhaust gas in the cylinder with a new air-fuel mixture, the scavenging is performed 100 times,
Alternatively, the displacement of the front pump 601 may be set. However, in order to deal with NOX in the exhaust gas, the displacement of the front pump 601 may be reduced so that a portion of the exhaust gas a remains as shown in FIG. In this way, part of the exhaust gas is allowed to remain in the cylinder, that is, the exhaust gas is recirculated, which has the advantage of lowering the maximum combustion temperature and reducing the generation of NOx. Further', the first
The engine 1 shown in the figure has a larger stroke relative to the cylinder bore than conventional engines.

Therefore, sufficient combustion time can be taken for the air-fuel mixture in the cylinder, complete combustion can be achieved, and CO, HC
It is also possible to measure the reduction of

The engine 1 shown in FIG. 1 uses a piston-type pump, and has an intake port (70) that is opened and closed by an intake valve 151.
In order to receive a fresh air-fuel mixture from 1 and exhaust the exhaust gas through the exhaust hole 27 at the bottom of each cylinder, the air-fuel mixture can be fed into the cylinder without being mixed with residual exhaust gas, and scavenging can be achieved. can be done completely. As a result, the combustibility of the engine can be improved and the reliability of the engine can be improved.

Moreover, the valve opening timing, period, and valve opening amount of each air supply valve 15 can be easily set to desired values by the action of the differential pressure piston 18. Therefore, the resistance to the air-fuel mixture flowing into the cylinder can be reduced, contributing to an improvement in output.

The engine 1 shown in FIG. 1 can be similarly constructed as a water-cooled four-cylinder in-line engine or a horizontally opposed engine, and similar effects can be obtained.

If used, the air supply valve can be operated effectively, the scavenging performance can be improved, and the output can be improved.

[Brief explanation of drawings]

FIG. 1 is a side partial sectional view of an engine as an embodiment of the invention, FIG. 2 is a front partial sectional view of the same engine, FIG. 3 is an explanatory diagram of the operation of the same engine at the time of explosion, and FIG. 4 5 is an explanatory diagram of the operation of the same engine during expansion, FIG. 5 is an explanatory diagram of the operation of the same engine during exhaust and scavenging, and FIG. 6 is an explanatory diagram of the operation of the same engine during compression. 1...Engine, 501...171st nong, 60
1... Front pump, 701... Air supply boat, 8.
...Crankshaft, 151...Air supply valve, 16...
・Valve body, 18...Differential pressure piston, 24...
・Ihihi device, Fl...force received by the valve body, F2...
・The force that the differential pressure piston receives. Width 2M

Claims (1)

[Claims] a piston type pump that is driven by the crankshaft and pressurizes the mixture from the mixture intake system and pressure-feeds the mixture to the combustion cylinder through the air supply boat; and an air intake valve that connects and connects the air intake port. In a two-stroke internal combustion engine configured to scavenge residual exhaust gas in the combustion cylinder using the piston pump, the intake valve has a valve opening force due to a pressure difference between the combustion cylinder side and the intake port side. A two-stroke internal combustion engine characterized in that it is integrally connected to a differential pressure piston that receives a force in the direction of opening the valve due to a pressure difference between the piston and the piston.