JPH07317550A - Crank chamber supercharged engine - Google Patents

Abstract

PURPOSE:To provide an engine of crank chamber supercharge type which can enhance the engine output through enhancement of the responsiveness of a reed valve and can prolong its lifetime. CONSTITUTION:A crank chamber 23 is partitioned into a suction chamber A and a compression chamber B by putting a connecting rod 17 in slide contact with the internal circumferential walls 2a, 2b of a crank case 2, and a suction passage 35 is connected with the suction chamber A and the discharge port 40 of the compression chamber B is connected with the combustion chamber so that a crank chamber supercharged engine 1 is formed. A reed valve 42 to prevent the counter-flow of the suction gas is installed at the discharge port 40, with which a suction tank 45 functioning as a pressure accumulating chamber C is connected. A suction pipe 46 in communication with the combustion chamber is connected with the suction tank 45, and the protruding amount of the suction pipe 46 into the suction tank 45 is made smaller than the distance from the open end 46a of the suction pipe 46 to the suction tank inner wall surface confronting the suction pipe open end.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crank chamber supercharged engine which is supercharged by utilizing a change in volume of a crank chamber.

[0002]

2. Description of the Related Art As a crank chamber supercharged engine of this type, a positive displacement supercharger having a piston as a mover and a crank chamber as a compression chamber has been conventionally known. This is because the negative pressure in the crank chamber when the piston moves up is used to suck air, and when the piston moves down, the air in the crank chamber is compressed and supercharged into the combustion chamber.

However, in the above-mentioned conventional supercharged engine utilizing the elevation of the piston, the volume of the crank chamber is wasted, and the filling efficiency is apt to deteriorate due to the thermal expansion of air, so that a sufficient engine output cannot be obtained. There is.

Therefore, the applicant of the present application divides the connecting rod housing chamber surrounded by the crank chamber, the crank web and the piston into a suction chamber and a compression chamber by the connecting rod, and compresses and burns the air sucked by the swinging of the connecting rod. A crank chamber supercharged engine that supercharges a room has been proposed (see Japanese Patent Laid-Open No. 6-93869). According to this
Each time the crankshaft makes one revolution, air can be pumped into the combustion chamber by a volume substantially swept by the connecting rod, so that the supercharging pressure can be increased as compared with the conventional structure, and the engine output can be improved accordingly. .

In the engine according to the above proposal, a reed valve is arranged at the discharge port of the compression chamber, and the discharge port and the combustion chamber are connected to each other through an intake tank and an intake pipe. There is. The reed valve opens when the internal pressure of the compression chamber becomes higher than the internal pressure of the intake tank, and closes when the internal pressure becomes lower than the internal pressure of the intake tank.

When the above structure is applied to a four-cycle engine, the intake valve is opened once every two revolutions, so that twice as much compressed air as one revolution of the crankshaft is supplied into the combustion chamber.

[0007]

By the way, in the supercharged engine of the above publication, the intake pipe is projected into the intake tank,
The structure is such that the projecting end opening is close to the inner wall of the intake tank. As a result, it is possible to prevent the influence of the pressure fluctuation in the intake tank from directly affecting the intake valve opening. However, it has been found that the adoption of this structure tends to shorten the reed valve opening time when the intake valve is open. This is considered to be due to the following reasons.

That is, in the case of a four-cycle engine, when the intake valve opens, the internal pressure of the intake tank drops, so the reed valve opens from the point when the internal pressure of the compression chamber is relatively low. If it is brought too close to, the pressure drop that occurs when the intake valve is opened is delayed in reaching the reed valve, the response of the reed valve is delayed, and the opening time is shortened. As a result, it may be impossible to secure sufficient supercharging.

In order to secure the above supercharging amount, it is conceivable to increase the amount of air passing through the reed valve by enlarging the reed valve or increasing the opening degree. However, there is a limit to the method of enlarging the reed valve and increasing the opening because it is difficult to secure the installation space.

Further, if the reed valve is opened and closed in a short time, a large impact force is applied, so that the reed valve may be deformed or damaged due to long-term use. Improvement is requested.

The present invention has been made in view of the above circumstances, and a crank chamber supercharged engine capable of improving the responsiveness of the reed valve to secure a supercharging amount and extending the life by absorbing impact force. Is intended to provide.

[0012]

According to a first aspect of the present invention, a connecting rod housing chamber surrounded by a crank chamber, a crank web and a piston is divided by a connecting rod into a suction chamber and a compression chamber, and a suction passage is provided in the suction chamber. In a crank chamber supercharged engine in which the discharge port of the compression chamber is connected to the combustion chamber, a reed valve for preventing backflow of intake air is provided at the discharge port of the compression chamber, and the pressure is accumulated in the discharge port. An intake tank that functions as a chamber, and an intake pipe that communicates with the combustion chamber is connected to the intake tank, and the amount of protrusion of the intake pipe into the intake tank is opposite from the opening end of the intake pipe. It is characterized by making it smaller than the distance to the inner wall of the intake tank.

The invention of claim 2 is characterized in that the valve plate of the reed valve is made of a light alloy material.

The above light alloys include titanium, magnesium,
Beryllium, duralumin, etc. can be adopted, and a composite material of these and FRP can be adopted.

According to a third aspect of the present invention, a stopper portion for restricting the opening of the valve plate is arranged on the lift side of the reed valve, and an elastic body is arranged at the valve plate contact portion of the stopper portion. It has a feature.

Here, it is desirable that the stopper portion has the same size as the valve plate or a slightly larger size. This is because if the size of the stopper portion is smaller than the valve plate, the protruding portion of the valve plate may be broken. Further, the stopper portion itself may be made of an elastic body.

The invention according to claim 4 is characterized in that an elastic body is arranged at the opening edge portion of the discharge port with which the valve plate of the reed valve abuts, and the invention according to claim 5 is the tip of the valve plate. It is characterized in that an elastic body is arranged in the portion.

[0018]

According to the crank chamber supercharged engine of the first aspect of the present invention, the amount of projection of the intake pipe into the intake tank is made smaller than the distance to the inner wall of the intake tank, so that it occurs when the intake valve is opened. The speed at which the pressure drop reaches the reed valve becomes faster, and as a result, the opening time of the reed valve becomes faster and the opening time can be lengthened. As a result, the supercharging amount can be sufficiently secured without increasing the size of the reed valve or the opening degree, and the engine output can be improved.

Further, since the opening time of the reed valve can be extended, the opening / closing speed can be slowed down, the impact force acting on the valve plate at the time of closing can be reduced, and the life of the reed valve can be extended accordingly.

According to the invention of claim 2, since the light alloy material such as titanium is used for the valve plate of the reed valve, the impact force can be reduced by reducing the weight of the valve plate, and the strength can be improved without increasing the plate thickness. The life of the reed valve can be extended.

According to the third aspect of the present invention, since the elastic member is disposed in the stopper portion with which the valve plate of the reed valve abuts, the impact force on the valve plate can be mitigated to suppress deformation and damage, and the life is extended. it can.

In the invention of claim 4, since the elastic body is arranged at the opening edge portion of the discharge port with which the valve plate of the reed valve abuts,
Further, in the invention of claim 5, since the elastic body is arranged at the tip end portion of the valve plate, the impact force at the time of closing can be alleviated, and in this case as well, the life can be extended.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 are views for explaining a crank chamber supercharged engine according to an embodiment of the present invention, and FIG. 1 is a sectional side view of the engine of the present embodiment, FIG. 3 is a sectional view taken along the line II-II and a sectional view taken along the line III-III of FIG. 1, FIG. 4 is an enlarged view of the connecting rod small end portion, and FIG. 5 is an enlarged view of the reed valve. In this embodiment, a case where the present invention is applied to a 4-cycle single cylinder engine will be described as an example.

In the figure, reference numeral 1 is a horizontal four-stroke single cylinder engine of this embodiment, and an air-cooled cylinder block 3 is connected to a mating surface of a crankcase 2 of the engine 1, and the cylinder block 3 A cylinder head 4 is connected to the mating surface of. A combustion recess 4a forming a combustion chamber is provided in a portion of the mating surface of the cylinder head 4 facing the cylinder bore 3a, and an ignition plug (not shown) is inserted in the recess 4a.

An intake port 5 and an exhaust port 6 are opened in the combustion recess 4a of the cylinder head 4, respectively.
The intake port 5 is led out to the upper wall side of the cylinder head 4, and the exhaust port 6 is led out to the lower wall side. An intake valve 7 is provided at the combustion chamber opening of the intake port 5, and an exhaust port 6 is provided.
An exhaust valve 8 is arranged at the opening of the combustion chamber so that each opening can be opened and closed. The intake valve 7 and the exhaust valve 8 are urged in a closing direction by a valve spring 9.

Valves 7 and 8 are provided on the cylinder head 4.
A cam shaft 10 as a valve mechanism for opening and closing is arranged in a direction perpendicular to the plane of the drawing. One end of the cam shaft 10 is connected to a drive sprocket 13 (see FIG. 2) connected to a crank shaft 20 described later through a sprocket and a chain 10a (see FIG. 3) not shown. A pair of rocker shafts 11, 11 extending in parallel with the cam shaft 10 are arranged above and below the cam shaft 10, and a rocker arm 12 is swingably attached to each shaft 11. One end of the rocker arm 12 is in contact with the cam nose of the cam shaft 10, and the other end is in contact with the upper ends of the valves 7 and 8.

Cylinder bore 3 of the cylinder block 3
A piston 16 is slidably inserted and arranged in a. With the piston 16 as a boundary, the crank chamber 2 is provided by the cylinder bore 3a and the crankcase 2 on the opposite side of the combustion chamber.
3 is formed. This piston 16 has a connecting rod 17
A small end 17a of the connecting rod 17 is connected via a piston pin 18 and a bearing 19, and a large end 17b of the connecting rod 17 is connected to a crank pin 21 of a crankshaft 20 via a bearing 22.

The crank shaft 20 is housed in the crank chamber 23a of the crank case 2 in the crank chamber 23. The pair of crank webs 24 formed in a disk shape are connected to each other by the crank pin 21. A journal portion 25 is integrally formed with the crank web 24 by being connected to the crank web 24. The journal portion 25 is supported by the crank case 2 via a journal bearing 26.
The journal portion 25 projects outward from the crankcase 2, and a generator 28 is mounted on one of the projecting portions. In addition, 27 is an oil seal.

The left and right inner side walls 2a of the crankcase 2 orthogonal to the crankshaft 20 and the notches 3c formed in the upper and lower portions of the fitting portion 3b of the cylinder block 3 to the crankcase 2 are flush with each other. And left and right inner side walls 2
a and the notch 3c have left and right side surfaces 1 of the connecting rod 17.
7c is in sliding contact with a minute gap, and the outer peripheral surface of the large end 17b of the connecting rod 17 is extremely minute on the arcuate inner peripheral wall 2b formed so as to surround the crankshaft of the crankcase 2. They are in sliding contact with a gap. The left and right inner side walls 2a of the crankcase 2 are provided with circular recesses 2c for accommodating and disposing the crank webs 24, and a slight gap is provided between the recesses 2c and the crank webs 24. ing. And crank web 2
The connecting rod side wall 24a of No. 4 and the left and right side surfaces 17c of the connecting rod 17 are in sliding contact with each other with a minute gap.

Further, a triangular recess 16a is provided in the skirt portion of the piston 16, and the recess 16a is formed.
The portion facing the outer periphery of the skirt is a notch 16b. The small end 1 of the connecting rod 17 is provided in the recess 16a.
7a is inserted and arranged. The outer peripheral surface of the small end 17a of the connecting rod 17 is in sliding contact with the inner peripheral surface of the recess 16a, and the left and right side surfaces 17c are in sliding contact with the left and right side surfaces 16c of the recess 16a with a minute gap.

With the above construction, the portion surrounded by the crank chamber 23, the crank web 24, and the piston 16 is a connecting rod accommodating chamber. This connecting rod accommodating chamber is provided when the piston 16 is located near the top dead center. At the crank angles other than the above, the connecting rod 17 fits into the left and right inner side walls 2a of at least one of the crankcase 2 or the notch 3c of the cylinder block 3 in the upper and lower parts, and the connecting rod 17 separates the suction chamber A and the compression chamber B. It is divided. Further, when the piston 16 is located at the bottom dead center, the connecting rod 17 is not fitted to the left and right inner side walls 2a, 2a, but the skirt end of the piston 16 almost coincides with the end of the cylinder bore 3a.
The division of the suction chamber A and the compression chamber B by 7 is maintained.
In this way, as the crankshaft 20 rotates clockwise from the state where the piston 16 is located at the top dead center, as shown in FIG.
By moving to the two-dot chain line position, and further to the solid line position, the volume of the suction chamber A increases and air is sucked in, and the volume of the compression chamber B decreases, and the air sucked in the previous stroke is compressed. The feeder is configured. Incidentally, such a structure is described in detail in the above-mentioned JP-A-6-93869.

A suction passage 35 communicating with the suction chamber A and opening downward is integrally formed on the lower surface of the crankcase 2, and a cover 36 for closing the suction passage 35 is formed at the bottom opening of the suction passage 35. It is installed. A suction port 35a is formed on the wall surface of the suction passage 35 on the front side in FIG. 1 so as to be oriented in the crankshaft direction, and a downstream end of a suction pipe 37 is connected to the suction port 35a. The suction pipe 37 extends outward through the side of the engine and has an upstream end connected to an air cleaner (not shown).

An intake passage 38 that opens upward is integrally formed on the upper surface of the crankcase 2. The intake passage 38 has a partition wall 39 that separates the passage 38 from the compression chamber B.
Are integrally formed. The outer peripheral surface of the connecting rod 17 is in sliding contact with the inner surface of the partition wall 39. A discharge port 40 that connects the intake passage 35 and the compression chamber B is formed in the partition wall 39. Since the engine 1 of this embodiment is mounted on a vehicle with the cylinder bore axis oriented horizontally as shown in FIG. 1, the discharge port 40 is located above in the vertical direction and the intake port 35a is located below in the vertical direction. It will be located.

A reed valve 42 is openably and closably arranged on the outer surface of the discharge port 40 of the partition wall 39. The reed valve 42 includes a valve plate 41a made of a light alloy material containing titanium as a main component. And a stopper 41b which is arranged on the lift side of the reed valve 42 and regulates the opening of the valve plate 41a. One end of the stopper 41b and the valve plate 41a is attached to the partition wall 39 by a bolt 43. It is fixed together. The stopper 41b is formed in the same size as the valve plate 41a, and an elastic material 41c made of rubber or the like is fixed to the valve plate contact surface of the stopper 41b by baking. As a result, the impact force on the valve plate 41a is alleviated, and the life is extended.

An intake tank 45 forming a pressure accumulating chamber C is connected to the intake passage 38. This intake tank 45
An intake pipe 46 is connected to the side wall of the intake pipe 4
6 is connected to the intake port 5 of the cylinder head 4. A vaporizer 47 is provided in the middle of the intake pipe 46, and a fuel tank 49 is connected to the vaporizer 47 via a pump 48. By disposing this carburetor 47 on the downstream side of the intake tank 45 of the intake pipe 46, the responsiveness of acceleration / deceleration is improved.

The upstream end opening 46a of the intake pipe 46 is also provided.
Is flush with the inner wall of the intake tank 45, whereby the amount of protrusion of the intake pipe 46 into the intake tank 45 is set to zero. By setting the amount of protrusion of the intake pipe 46 to 0, the pressure drop when the intake valve 7 is opened immediately reaches the reed valve 42, and the opening time of the reed valve 42 is lengthened accordingly, thus increasing the supercharging amount. Can be achieved.

The intake tank 45 and the intake pipe 37 communicate with each other through a bypass passage 50. The bypass passage 50 can be opened and closed by a bypass valve 51.
In this bypass valve 51, the valve body 51a is connected to the diaphragm chamber 52.
The diaphragm chamber 52 is connected to the downstream end (downstream of the carburetor 47) of the intake pipe 46 via a negative pressure passage 53. The bypass valve 51 lowers the pressure in the intake tank 45 by opening the bypass passage 50 by the negative pressure when the intake negative pressure increases when the throttle opening is small, for example.

Reference numeral 60 denotes a lubrication device, which comprises a first lubrication system 61 and a second lubrication system 62 provided independently of the first lubrication system 61. The first lubrication system 61 includes an oil supply pipe 6 with a supply pump 64 interposed in a first storage tank 63 filled with oil for four cycles.
5 and the supply port 65a of the supply pipe 65 is connected to the portion of the camshaft 10 that constitutes the valve mechanism of the cylinder head 4. The oil that lubricates the camshaft 10 is used in the chain chamber 10 in which the chain 10a is housed.
2b, lubricate the chain 10a, the driving sprocket 13, the driven sprocket (not shown) and the journal bearing 26 (with a seal ring) on the left side in FIG.
After that, it is collected in the first storage tank 63 through the recovery pipe 66.

In the second lubrication system 62, the main supply pipe 7 is provided in the second storage tank 70 filled with oil for two cycles.
1, the pressure feed pump 72 is connected, the first and second auxiliary supply pipes 73, 74 are connected to the pump 72, the first auxiliary supply pipe 73 is connected to the piston sliding portion of the cylinder block 3, and The second auxiliary supply pipe 74 is connected to the journal bearing portion of the crank chamber 23.

Although not shown, the pressure pump 72 is an improved solenoid of an electromagnetic type automatic loop pump, and is of a type in which an armature is fixed to a push rod of a plunger and the armature is sucked by a solenoid. . As a result, the discharge pressure from the pump 72 increases, and it is possible to overcome the supercharging pressure and supply oil.

Oil discharge port 73 of the first auxiliary supply pipe 73
Reference character a denotes a piston 1 located at the bottom dead center, which penetrates the liner portion of the cylinder block 3 in a direction orthogonal to the crankshaft 20.
It is located closer to the crank chamber than the second piston ring 6 is. Further, two oil reservoir recesses 75 and 76 are cut out in parallel in the crankshaft direction on the outer surface of the piston 16 closer to the crank chamber than the second piston ring. The recess 75 is formed by the oil supplied from the discharge port 73a and accumulated when the piston 75 moves to coincide with the discharge port 73a, and the recess 76 is formed by the oil supplied from the discharge port 73a as described below. ,
Lubrication is performed when each of the discharge ports 73a is blocked by the piston 16, and as a result, troubles in lubrication caused by the discharge ports 73a being blocked by the piston 16 are prevented.

Further, an oil guide groove 81 extending in the circumferential direction is formed on the outer peripheral surface of the small end portion 17a of the connecting rod 17, and the guide groove 8 is formed on the piston 16.
A communication hole 77 that communicates 1 with the lower recess 76 is formed. A communication hole 78 that communicates with the piston pin 18 and the bearing 19 is formed on the side of the small end 17a opposite to the communication hole 77. As a result, a part of the oil in the guide groove 81 supplied from the discharge port 73a and the oil recovery hole 80 described below is supplied from the communication hole 78 to the bearing 19, and the remaining part of the oil is discharged from the communication hole 77. Edge 17
It is supplied to the sliding surface between a and the piston 16, and further supplied to the concave portion 76.

A corner portion between the bottom of the intake passage 38 and the partition 39 is located at the lowest position in the intake tank 45 as a whole, and the accumulator chamber C and the crank chamber 23 are located in the corner portion.
A small-diameter oil recovery hole 80 that communicates with The recovery hole 80 is set to a size such that the amount of air leakage in the pressure accumulating chamber C does not hinder supercharging. The recovery hole 80 is for supplying the oil accumulated at the bottom of the intake passage 38 to the sliding surface of the piston 16 and the like, and a part of the recovery hole 80 passes through the guide groove 81 from the communication holes 77 and 78 to the piston 16, It is supplied to the connecting rod small end portion 17a, the sliding surface of the piston pin 18, and the sliding surface of the piston cylinder bore.

Oil discharge port 74 of the second auxiliary supply pipe 74
The letter a passes through the crankcase 2 and reaches the journal bearing 26 on the right side in FIG. The oil supplied to the right journal bearing 26 is supplied to the inner peripheral walls 2a and 2b of the crankcase 2 and the clearance between the circular recess 2c and the crankshaft 20, and to the sliding surfaces.

Further, the intake passage 3 of the crankcase 2
A recovery passage 83 that opens into the passage 35 is formed in the cover 36 that closes the passage 5. A recovery pipe 84 is connected to the recovery passage 83, and the recovery pipe 84 is connected to the second storage tank 70. As a result,
The oil supplied from the second auxiliary supply pipes 73 and 74 lubricates each sliding surface, then returns from the suction chamber A of the crankcase 2 to the upper surface of the cover 36 in the suction passage 35, and is collected from there. In the present embodiment, the engine 1 is placed horizontally, the compression chamber B having a high supercharging pressure is arranged upward, and air is taken in from below the crankcase 2. Therefore, the interaction between gravity and supercharging pressure causes the lubricating oil to collect at the lowermost portion of the crankcase 2, that is, the upper surface of the cover 36, so that the oil can be reliably collected and reused. is there.

Next, the function and effect of this embodiment will be described. In the engine 1 of this embodiment, the connecting rod 17 is oscillated to the uppermost position after the outer peripheral surface of the large end 17b of the connecting rod 17 approaches the inner peripheral wall 2b of the arc portion of the crankcase 2 every time the crankshaft 20 makes one revolution. Thus, the volume of air swept by is pumped and stored in the intake tank 45. Then, in the intake stroke of the engine 1, the intake valve 7
Is opened, 2 times of the compressed air for one rotation of the crankshaft 20
Double the air will be supercharged into the combustion chamber.

Further, in the lubricating device 60 of this embodiment, the oil for four cycles in the first storage tank 63 is supplied to the camshaft 10 portion of the valve mechanism by the first lubricating system 61.
The oil that lubricates this is collected in the storage tank 63 through the chain chamber 10b, and is then supplied to the valve mechanism again.

Further, the second lubrication system 62 causes the oil for the second cycle in the second storage tank 70 to move to the piston 1
In addition to being supplied to the 6th part, it is supplied to the journal bearing 26 part. A part of the oil splashed up by the centrifugal force of the crankshaft 20 flows into the pressure accumulating chamber C together with the intake air and stays in the corner portion of the partition wall 39. The collected oil is supplied again to the piston 16 portion through the recovery hole 80. The oil that lubricates the sliding surfaces and the rotating surfaces returns to the upper surface of the cover 36 of the crankcase 2 due to the interaction between gravity and supercharging pressure, and from there, passes through the recovery pipe 84 and the second oil.
It is collected in the storage tank 70 and is again supplied to each lubricated part.

As described above, according to the lubrication apparatus 60 of the present embodiment, the first lubrication system 6 recovers the oil for four cycles from the first storage tank 63 after supplying it to the camshaft 10 part.
No. 1 and the second lubrication system 6 that supplies the two-cycle oil from the second reservoir 70, which is provided independently of each other, to the sliding surface and the rotating surface of the piston 16 and the crankshaft 20.
Since it is constituted by 2, the oil for 4 cycles and the oil for 2 cycles can be independently supplied to the valve operating system and the piston crank system, respectively, and the durability of the engine 1 can be improved.

Further, in this embodiment, since the discharge port 40 is located at the upper part and the oil from the second lubrication system is supplied to the upstream side of this, the reed valve 42 is provided.
A large amount of oil does not adhere to the valve, and as a result, it is possible to avoid deterioration of the reed valve function. Further, since the oil flowing from the crank chamber 23 into the pressure accumulating chamber C is collected in the corner portion of the partition wall 39 which is a low place, the recovery hole 80 is formed to re-supply the oil accumulated in the corner portion into the crank chamber 23. Also from this point, it is possible to avoid the functional deterioration of the reed valve 42 due to the accumulated oil. As a result, it is possible to avoid an increase in white smoke and a reduction in output due to horsepower loss, and it is possible to reduce oil consumption and improve lubrication efficiency.

Further, in this embodiment, a recovery passage 83 is formed in the cover 36 on the lower surface of the crankcase 2, and the passage 83 is formed.
Since the oil is collected in the second storage tank 70 via the collecting pipe 84, the oil with which the sliding surfaces and the rotating surfaces are lubricated can be reliably collected, and the lubricating efficiency can be improved also from this point.

According to this embodiment, the intake tank 45
Since the upstream end opening of the intake pipe 46 is connected to and the amount of protrusion of the intake pipe 46 into the intake tank 45 is set to 0, the pressure drop when the intake valve 12 is opened reaches the reed valve 42 immediately, As a result, the responsiveness of the reed valve 42 can be improved, and as a result, the supercharging amount can be sufficiently secured and the engine output can be improved. The amount of protrusion of the intake pipe 46 into the intake tank 45 does not necessarily have to be set to 0, and the amount of protrusion may be set smaller than the distance from the opening to the opposing inner wall surface of the intake tank. Even in such a case, the responsiveness of the reed valve 42 can be secured. By the way, if the amount of protrusion is larger than the above distance, the arrival speed of the pressure drop to the reed valve 42 when the intake valve 12 is opened becomes slow, and the open time length of the reed valve 42 becomes short.

Further, in this embodiment, the valve plate 41a of the reed valve 42 is made of a titanium alloy material, and the elastic member 41c is formed at the contact portion of the stopper 41b with the valve plate 41a. And the impact force can be suppressed, and the service life for long-term use can be extended.

In the above embodiment, the case where the present invention is applied to a 4-cycle single cylinder engine has been described as an example, but the present invention can also be applied to a 4-cycle multi-cylinder engine and a 2-cycle engine. When applied to this two-cycle engine, the discharge port 40 of the compression chamber B is communicated with the scavenging passage.

6 and 7 are claims 4 and 5, respectively.
FIG. 6 is a view for explaining a reed valve of a crank chamber supercharged engine according to an embodiment of the present invention, in which the same reference numerals as in FIG. 5 denote the same or corresponding parts.

In FIG. 6, a mounting seat 90 having a discharge port 90a communicating with the discharge port 40 is bolted and fixed to the outer surface of the partition wall 39 which separates the compression chamber B and the pressure accumulating chamber C, and the mounting seat 90 is fixed.
This is an example in which a valve plate 41a is disposed at the discharge port 90a of the above, and an elastic body 91 made of rubber or the like is baked and fixed to the opening edge of the discharge port 90a of the mounting seat 90 with which the valve plate 41a abuts.

FIG. 7 shows the discharge port 90 of the valve plate 41a.
This is an example in which an elastic body 93 made of rubber or the like is baked and fixed to the tip edge portion that abuts the opening edge of a.

According to each of the above-mentioned embodiments, since the elastic bodies 91 and 93 are arranged at the portions of the reed valve 42 which come into contact with the valve plate 41a, the impact force at the time of opening and closing can be alleviated and deformation and damage can be suppressed. The life can be extended.

[0059]

As described above, according to the crank chamber supercharged engine of the first aspect of the present invention, the protrusion amount of the intake pipe into the intake tank is smaller than the distance from the intake pipe opening to the intake tank inner wall surface. Therefore, the responsiveness of the reed valve to the pressure drop when the intake valve is opened can be improved, the supercharging amount can be increased by the amount that the reed valve opening time can be lengthened, and as a result, the engine output can be improved. is there. Further, since the opening time can be extended, the opening / closing speed can be reduced, the impact force on the valve plate at the time of closing can be mitigated, and the life of the reed valve can be extended accordingly.

According to the second aspect of the present invention, since the light alloy material is used for the valve plate, the impact force against the valve plate itself can be suppressed, the strength can be improved, and the life can be further extended.

According to the third aspect of the present invention, since the elastic member is provided in the stopper portion with which the valve plate abuts, the impact force when the valve plate is closed can be alleviated, and from this point, the life can be extended.

In the invention of claim 4, an elastic body is arranged at the opening edge portion of the discharge port with which the valve plate abuts, and in the invention of claim 5, the elastic body is arranged at the tip portion of the valve plate. As a result, the impact force at the time of closing can be relaxed, and in this case also, there is an effect of extending the life.

[Brief description of drawings]

1 is a sectional side view for explaining a crank chamber supercharged engine according to an embodiment of the present invention.

2 is a cross-sectional rear view (cross-sectional view taken along the line II-II in FIG. 1) showing a crankshaft portion of the engine of the embodiment.

FIG. 3 is a sectional front view (a sectional view taken along line III-III in FIG. 1) showing a piston portion of the engine of the embodiment.

FIG. 4 is an enlarged sectional view of a connecting rod small end portion of the engine of the embodiment.

FIG. 5 is an enlarged sectional view showing a reed valve portion of the engine of the above embodiment.

FIG. 6 is a sectional view showing a reed valve portion according to an embodiment of the invention of claim 4;

FIG. 7 is a sectional view showing a reed valve portion according to an embodiment of the invention of claim 5;

[Explanation of symbols]

1 Crank chamber supercharged 4-cycle engine 2 Crank case 2a, 2b, 2c Crank case inner peripheral wall 17 Connecting rod 23 Crank chamber 40, 90a Discharge port 42 Reed valve 41b Stopper part 41c, 91, 93 Elastic body 45 Intake tank 46 Intake pipe A suction chamber B compression chamber C pressure storage chamber

Claims (5)

[Claims] 1. A connecting rod accommodating chamber surrounded by a crank chamber, a crank web and a piston is divided into a suction chamber and a compression chamber by a connecting rod, and a suction passage is connected to the suction chamber and a discharge port of the compression chamber is connected to the suction chamber. In a crank chamber supercharged engine connected in communication with a combustion chamber, a reed valve for preventing backflow of intake air is provided at the discharge port of the compression chamber, and an intake tank that functions as a pressure accumulation chamber is connected to the discharge port, An intake pipe communicating with the combustion chamber is connected to the intake tank, and the amount of protrusion of the intake pipe into the intake tank is smaller than the distance from the opening end of the intake pipe to the inner wall of the intake tank facing the intake pipe. Crank chamber supercharged engine. 2. The crank chamber supercharged engine according to claim 1, wherein the valve plate of the reed valve is made of a light alloy material. 3. A stopper portion for restricting an opening of a valve plate is provided on the lift side of the reed valve, and an elastic body is provided at a valve plate contact portion of the stopper portion. A crank chamber supercharged engine characterized by the following. 4. The crank chamber supercharged engine according to claim 1, wherein an elastic body is provided at an opening edge portion of the discharge port with which the valve plate of the reed valve abuts. 5. A crank chamber supercharged engine according to any one of claims 1 to 4, wherein an elastic body is provided at a tip portion of the valve plate.