JPS61200330A - Supercharged-type four-cycle engine - Google Patents

Abstract

PURPOSE:To reduce a degree of passage resistance as well as to improve charging efficiency ever so high, by opening or closing both suction and discharge ports leading to a crankcase with a rotary valve lying astride both these ports, in a device which compresses suction air in utilizing a pressure variation inside the crankcase and feeds a combustion chamber with this compressed air. CONSTITUTION:A suction port 12 and a discharge port 13 leading to a crank chamber 5 are formed in an upper part of a crankcase 2, and a carburetor 14 is connected to the suction port 12, while a suction pipe 16 leading to a suction air port 15 of a cylinder head 3 is connected to the discharge port 13. In addition, there is provided with a rotary valve 17 lying astride both these ports 12 and 13, and this rotary valve is interlocked with a crankshaft 4, rotating it, and at compression and exhaust strokes, the suction port 12 is opened but at explosion and suction strokes, the discharge port 13 is opened as well. And, with a pressure variation in the crank chamber 5 due to reciprocating motion of a piston 10, suction air is inhaled out of the suction port 12, and the suction air compressed at the inside of the crank chamber 5 is fed to a combustion chamber 1a via a discharge port 13, the suction pipe 16 and a suction valve 8.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a so-called crankcase supercharged four cycle engine.

(Prior Art) Conventionally, according to Japanese Patent Application Laid-open No. 47-35516, an intake port b and a discharge port C connected to a crank chamber a are formed in an engine body as shown in FIG. A supercharged four-cycle engine is known that compresses and supplies intake air using pressure fluctuations in the crank chamber a. A reed valve e that allows intake air to flow in is provided at the intake port b, and a reed valve e that allows intake air to flow out from the crank chamber a during the explosion stroke and intake stroke is installed at each of the discharge ports i to G. In general, it consists of

(Problem to be Solved by the Invention) In the above engine, since the intake air flows by pushing aside the reed piece of the reed valve e, this creates resistance and reduces the efficiency of intake air into the crank chamber a. In addition, if reed valve e is used, a relatively large dead space f, f will be formed around the valve, and this will cause the intake air in crank chamber a to There is a problem in that the primary compression ratio of the combustion chamber decreases, and as a result, the efficiency of filling the intake air into the combustion chamber cannot be sufficiently increased, making it impossible to expect a significant improvement in output.

SUMMARY OF THE INVENTION An object of the present invention is to solve these problems and provide an engine that can further improve output.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an engine body with:
A suction port and a discharge bow connected to the crank chamber are formed, and the intake air is sucked from the suction port into the crank chamber by utilizing pressure fluctuations in the crank chamber caused by the reciprocating motion of the piston, and from the discharge port into the combustion chamber. In a supercharged 4-stroke engine that compresses and supplies intake air to the engine, a rotary valve is provided that spans both ports, and the valve is rotated in conjunction with the crankshaft to perform the engine's compression stroke and exhaust stroke. It is characterized in that the suction port is opened and the discharge ports 1 to 1 are opened during the explosion stroke and the suction stroke.

(Example) The invention will now be described with reference to illustrated embodiments.

In the drawing, (1) shows the cylinder of the engine, (2) shows the crankcase below it, and (3) shows the cylinder head. The crankcase (2) contains a crank chamber (5) that houses the crankshaft (4). ) and a transmission chamber (6), and a valve drive camshaft (7), two intake valves (8), and one exhaust valve (9) are arranged in the cylinder head (3). The overall structure was an OHC type 3-valve 4-cycle single-cylinder engine. In the drawing, (1a) indicates the upper combustion chamber of the cylinder (1), a(ll indicates the piston, and (I'D indicates the connecting rod).

Then, a suction port (IZ) and a discharge port 0 connected to the crank chamber (5) are formed in the upper part of the crankcase (2), and the carburetor t'+@ is connected to the suction port GD, and the discharge port The intake pipe (le) connected to the intake port (ID) of the cylinder head (3) was connected to the port (13).

Here, according to the present invention, one coater pulp (171) is provided that spans both the ports oag, and the valve (2) is rotated in conjunction with the crankshaft (4) so that the valve (171) In addition to opening the suction port 0, the discharge port 0 is also opened during the explosion process and the intake process.

To explain this in detail, the rotary valve (17) includes a cylindrical valve housing l'lε formed on the crank chamber (5) side so as to straddle both the ports (lIe), and a valve inserted into the cylindrical valve housing l'lε. The valve body (19) is provided with through holes (19a) (19b) located in each half of the axial direction corresponding to each port (+2+■) and penetrating in the radial direction. The valve body (14+1) is engaged with a cam chain (2) extending between the crankshaft (4) and the valve drive camshaft (7) at its outer end sprocket (0). , the valve body a9 is rotated by the crankshaft (4) at a reduction ratio of 1/2, and a through hole (19a
) match, intake air is drawn into the crank chamber (5), and during the explosion process and intake process, the discharge port ae
The through hole (19b) is aligned with the crank chamber (5) so that intake air from the crank chamber (5) can be discharged. In the illustrated example, a centrifugal governor is attached to the sprocket (2) of the valve body 09 as shown in FIG. 4, and the valve body a9 is advanced as the engine speed increases. To be more specific, a pair of governor weights C22b) C22 are attached to the sprocket 2 with pins 22a) so as to be able to swing freely radially outward.
b), and spline-engages a spline collar 220) rotatably fitted to the sprocket (2) with the valve body 09, and engages the root of each weight Q2b) with the periphery of the collar C22C); each weight 122b)
Due to the radially outward rocking of this collar against the return spring (22e), the collar 〇! 2c), the valve body (19) was rotated in the advance angle direction.

(Function) Due to the pressure fluctuation in the crank chamber (5) caused by the reciprocating motion of the piston a0, intake air is drawn into the crank chamber (5) from intake ports 1 to (IZ) during the compression process and exhaust process of the engine, and during the explosion process. During the intake stroke, the compressed intake air discharged from the crank chamber (5) through the discharge port a3 into the intake pipe (I61) is discharged from the crank chamber (5) together with the intake air discharged from the crank chamber (5) through the intake valve (8). ) is supplied to the combustion chamber (1a) of the cylinder (1), and a supercharging effect is performed.This point is not particularly different from the conventional type, but since the conventional type uses a reed valve, the above-mentioned In contrast, the present invention has a rotary valve (17+) that rotates in conjunction with the crankshaft (4) to open and close both ports (Ibag), and unlike the conventional one, the intake air Compared to pushing the reed piece of the reed valve aside and passing through it, the passage resistance is smaller, and the efficiency of sucking air into the crank chamber (5) and the efficiency of discharging air from the crank chamber (5) are improved.

Also, each port a' is connected to the valve body a9 of the rotary valve a force.
b (The space between Iv and the crank chamber (5) is filled, the dead space around the valve is reduced compared to the conventional reed valve, and the volume of the crank chamber (5) is substantially reduced. The primary compression ratio of the intake air is increased, and the ratio of the volume of the intake system passage on the downstream side of the discharge port to the crank chamber (5) is increased, so that the primary compression ratio of the intake air is The amount of intake air that can be stored in this state is increased, and the filling efficiency of intake air is further improved.

Furthermore, the rotary valve (+7+) is different from differential pressure responsive ones such as reed valves in that its opening/closing timing can be changed, increasing the degree of freedom in changing the settings of output characteristics.

(Effects of the Invention) According to the present invention, the suction port 1~ and the discharge port 1~ connected to the crank chamber are formed, a rotary valve is provided spanning both ports, and the valve is interlocked with the crankshaft. The valve is configured to open and close both ports by rotating the valve, which reduces passage resistance compared to conventional reed valves, and reduces the dead space formed around the valve compared to conventional valves. It is possible to increase the primary compression ratio of the intake air entering the crank chamber and improve charging efficiency, and the opening and closing timing of the intake port and discharge port can be adjusted freely to match the required output characteristics. It has the advantage of being configurable.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a conventional engine, FIG. 2 is a partially low-level front view of an example of the engine of the present invention, and FIGS. 3 and 4 are the lines ■-■ in FIG. FIG. 5 is a sectional side view taken along the line rV-IV. FIG. 5 is a low-level plan view taken along the line v--v in FIG. (1a)...Combustion chamber (4)...Crankshaft (5)...Crank chamber a■...Piston 0...
・Suction port (131...Discharge port (+7+・
・Rotary valve

Claims (1)

[Claims] The engine body has an intake port and a discharge port that are connected to the crank chamber, and by utilizing pressure fluctuations in the crank chamber due to the reciprocating motion of the piston, intake air is drawn into the crank chamber from the intake port and then from the discharge port. In a supercharged four-stroke engine that compresses and supplies intake air to the combustion chamber, a rotary valve is provided that spans both ports,
The valve is configured to rotate in conjunction with the crankshaft to open the intake port during the compression stroke and exhaust stroke of the engine, and to open the discharge port during the engine's explosion stroke and intake stroke. Supercharged type 4
cycle engine.