JPH0223228A - Two-cycle gasoline engine - Google Patents

Abstract

PURPOSE:To increase output of an engine by providing a rotor capable of freely rotating in a crankcase on an eccentric shaft integral with a crankshaft and supporting the rotor on the crankcase through a parition rod capable of freely oscillating. CONSTITUTION:Crank arms 7a, 7b of a crankshaft 5 are circular crank arms 8a, 8b on the crank pin 6 side. The circular crank arms 8a, 8b are rotatably brought into close contact with the interiors of casings 12a, 12b disposed on the inner periphery of a crankcase 18, thereby partitioning pump chambers 18a, 18b. Rotors 11a, 11b rotatably fitted to eccentric shafts 9a, 9b forming a part of each of the crank arms 7a, 7b are accommodated in the respective pump chambers 18a, 18b. The respective rotors 11a, 11b are supported on the crankcase 16 through a partition rod 13 capable of freely oscillating to form a scavenging pump. The partition rod 13 has one end rotatably connected to a partition rod holding member 17b and the other end connected to the rotor 11b.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a two-stroke gasoline engine that aims to reduce fuel consumption and increase output by improving scavenging efficiency.

[Prior art] A reciprocating piston pump structure obtained from the crank chamber of a conventional power cylinder piston device is used as the only scavenging pump to overcome the low air intake ratio and low air intake efficiency caused by insufficient scavenging of a two-cycle gasoline engine. In order to improve this, there have been two-stroke gasoline engines that are equipped with separate reciprocating or double-sided cylinder-piston type scavenging pumps, Roots blower type scavenging pumps, etc. as scavenging pumps to improve volumetric efficiency.

[Problems to be Solved by the Invention] However, in a two-stroke gasoline engine equipped with a separate scavenging pump as described above, the volume of the engine itself increases and the weight increases, requiring a lightweight and small engine. Another problem is that it causes problems in mounting it on a vehicle (particularly a motorcycle), and there is a large output loss to drive the scavenging pump.

1. Means for Solving the Problems] A two-stroke gasoline engine according to the present invention that solves the problems listed in L includes at least one set of two-stroke power cylinder piston devices, and a crank pin side of a crank arm of the power cylinder piston device. A circular crank arm is provided which is circular and can slide on a casing on the inner periphery of the crankcase. A scavenging pump chamber sealed by the casing and the circular crank arm is provided on the crank journal side of the crank arm, and a crank is provided in the scavenging pump chamber. an eccentric shaft that forms part of the structure of the arm, connects the circular crank arm and the crank journal, and is provided with a rotor that is set eccentrically with respect to the rotational center axis of the crank journal and is rotatable around the rotational center axis of the crank journal; have,
The partition rod has one end rotatably connected to the partition rod holding member and the other end rotatably connected to the rotor, and the partition rod slides in the scavenging pump chamber, and the casing is shaped to slide on the rotor. It also includes a casing rotor type scavenging pump device in which an air intake port and an air outlet are provided before and after the holding portion of the partition wall opening.

[Function] In the two-stroke gasoline engine according to the present invention,
The crank pin side of the crank arm is circular, and the circular crank arm is slidable on a casing provided on the inner periphery of the crankcase between the crank pin and the crank journal. A pump chamber sealed by the casing is provided, and the pump chamber forms a part of the structure of the crank arm, connects the circular crank arm and the crank journal, and has a central axis of rotation of the crank journal and a An eccentric shaft is provided eccentrically, and a rotor rotatable around the eccentric shaft is provided, and both sides of the rotor are respectively connected to the pump chamber side side of the circular crank arm and the crank journal of the casing. One end is rotatably connected to a bulkhead rod holding member on the outer periphery of the rotor, and the pump chamber side side of the circular crank arm and the crank journal side of the casing are connected to the outer periphery of the rotor. The other end of the partition rod that slides while keeping a seal on the side surface of the partition rod is rotatably connected to the side surface of the partition rod. A fresh air intake port is provided on one side of the periphery, and a fresh air outlet port is provided on the other side, and the outer periphery of the rotor is sealed with the inner periphery of the casing except for the area between the intake port and the air outlet. It is equipped with a casing rotor type scavenging pump device that slides while moving, and the air outlet is connected to a scavenging port provided in the cylinder of the power cylinder piston device via a scavenging passage. The eccentric shaft of the casing rotor type scavenging pump device rotates to perform intake, compression, and mountain air strokes to scavenge air.

[Examples] Next, examples embodying the present invention will be described with reference to the attached drawings to provide an understanding of the present invention.

The attached FIG. 1 is a decompressed side sectional view of a two-stroke gasoline engine according to a first embodiment of the present invention, FIG. 2 is a partially cutaway plan view of FIG. 1, and FIG. is the first
FIG. 4 is a partially cutaway front view of FIG. 1, and FIG. 5 is a side sectional view of the two-stroke gasoline engine sequentially explaining the operating state of the two-stroke gasoline engine. It is.

As shown in FIGS. 1 and 3, the power cylinder piston device includes a cylinder 1, a piston 2, a piston pin 3, a connecting rod 4, a crankshaft 5, a cylinder head 27, a cylinder block 26, and the like as in a normal two-stroke gasoline engine. The main components include a crankcase 16 and a spark plug 29.

The casing rotor type scavenging pump device includes a crank arm 7a forming a part of the structure of the crankshaft 5;
The crankcase 16 has circular crank arms 8a and 8b, each of which has a circular crankpin 6 side, and is located between the crankpin 6 and the crank journals 10a and 10b, respectively.
The casings 12a, 12b provided on the inner periphery and the circular crank arms 8a, 8b are respectively set to slide and rotate while maintaining airtightness, and the crank arm 7a.

On the crank journal 10a, 10b side of 7b are circular crank arms 8a, 8b and casings 12a, 12b.
and pump chambers 18a, 1 sealed by casings 12c, 12d provided on both inner surfaces of the crankcase 16.
8b are provided respectively. The pump chambers 18a, 18
Inside b are circular crank arms 8a, 8b and a crank journal 1, which form part of the structure of crank arms 7a, 7b.
Connect 0a and iob, and crank journal 1
Eccentric shafts 9a and 9b are provided eccentrically with respect to the rotational center axes of 0a and 10b, respectively, and the eccentric shafts 9a and 9b are arranged at 180 degrees with the crank pin 6 in order to have a balance weight function and prevent vibration. The phase angle is set.

As shown in FIGS. 1 to 4, the eccentric shaft 9a,
Rotatable rotors 11a and 11b are provided around the rotor 9b, and both sides of each of the rotors 11a and 11b are connected to pump chambers 18a of the circular crank arms 8a and 8b.
, 1.8 b side side and casing 12c, 1
2d, and the bulkhead rod holding members 17a, 17b on the side of the scavenging passages 22a, 22b of the crankcase 16 have pivots 15a, 15.
Partition rods 13a and 13b are provided, one end of which is rotatably connected to the other end of the circular crank arm 8a, 8b on the side of the pump chambers 18a, 18b and the casings 12c, 12d while maintaining airtightness. Rod 13a
, 13b and the outer periphery of the rotors 11a, 11b are rotatably connected via pivots 14a, 14b that maintain airtightness. intake ports 20a, 20b and outlet port 21a.

The inner periphery except between 21b has a shape that maintains a seal and slides when the eccentric shafts 9a and 9b rotate, and the intake ports 20a and 20b are connected to pivots 15a and 15.
The air outlet 21a is also provided independently at the lower part of the air outlet 21a.
, 21b are independently provided above the pivots 15a, 15b.

In the first embodiment, the second, sixth, and
Since the seventh embodiment is adopted, these configurations will be explained below using FIGS. 1 to 4.

In the second embodiment, the reciprocating piston type pump structure obtained within the crankcase 16 by the actuation of the reciprocating piston 2 of the power cylinder piston device is not included as part of the scavenging pump device, and a set of the aforementioned The aforementioned circular crank arm 8a, eccentric shaft 9a,
Rotor lla, bulkhead rod 13a, pivot 14a.

15a, partition rod holding member 17a, pump chamber 18a,
Casing 12a, 12c, air intake port 20a, air outlet 2
A casing rotor type scavenging pump device having 1a as a main component, and the above-mentioned circular crank arm 8b as an air scavenging pump device.

Eccentric shirt 1-9b, rotor 11b, bulkhead rod 13b, pivots 14b, 15b, bulkhead rod holding member 17b, pump chamber 18b, casing 12b, 12d
The air is scavenged by a casing rotor type scavenging pump device whose main components are an air intake port 20b and an air outlet 21b.

In the sixth embodiment, the scavenging passage 22a and scavenging port 23a of the mixture scavenging pump device are set independently from the scavenging passage 22b and scavenging port 23b of the air scavenging pump device. .

In the seventh embodiment, the top dead center side opening of the piston 2 of the scavenging port 23b of the air scavenging pump device is the top dead center side opening of the piston 2 of the scavenging port 23a of the mixture gas scavenging pump device. The setting is such that it is disposed closer to the top dead center of the piston 2.

Although the fuel supply device is not shown, the intake pipe 2
4a is equipped with a carburetor, or the intake pipe 2
4a, intake port 20a, casing 12a, outlet port 21
A, a fuel injection device may be provided in either the scavenging passage 22a or the scavenging port 23a.

To explain the operation of the first embodiment described above using FIG. The disassembled side view on the right side shows the side of the casing rotor type scavenging pump device for air-fuel mixture, and (a) shows the state where the piston 2 is at the bottom dead center. , (b
) shows a state in which the crankshaft 5 has rotated 90 degrees and the piston 2 is moving from the bottom dead center to the top dead center, and (C) shows a state in which the crankshaft 5 has further rotated 90 degrees and the piston 2 is at the top dead center. , (d) shows that the crankshaft 5 is further 90
The crankshaft 5 rotates 90 degrees from the state shown in (d) to the state shown in a), and the piston 2 moves from the top dead center to the bottom dead center.
Repeat steps b), (C), and (d).

The operation of the scavenging pump device when repeating the above process is (b
), the eccentric shafts 9a, 9b and the rotor 11a,
llb rotates the bulkhead rods 13a and 13b to the side of the bulkhead rod holding members 17a and 17b, and has already opened the scavenging ports 23a,
23b is closed and scavenging is completed, then (C)
In the state of (c), the rotor 11a,
llb has already slid with the casings 12a, 12b through the intake ports 20a, 20b and is located at the lower part of the crankcase 16, and at this time, the bulkhead rods 13a, 13b are connected to the rotor 11.
As the pumps a and llb move, the pump is drawn out while sliding on the pivots 15a and 15b, and the air-fuel mixture (or the air that becomes the air-fuel mixture in a later stroke) is gradually sucked into the intake port 2Oa side of the pump chamber 18a. At the same time, the pump chamber 18a
At the outlet 21a side, the mixture 1 sucked in the previous step
Air (or air that becomes a mixture in a later stroke) is gradually compressed, and at the same time air is gradually sucked in at the intake port 20b side of the pump chamber 18b, and at the same time, the air is sucked in at the outlet port 21b side of the pump chamber 18b. The air sucked in during the stroke is gradually compressed.

In the next step (d), the rotor 11a,
11b slides on the casings 12a, 12b and is in a position facing the partition rod holding members 17a, 17b, and at this time, the partition rods 13a, 13b4. tO-9-11a,
1] b is pulled out the most while sliding on the pivots 15a and 15b as support shafts, and the pump chamber 18
At points a and 18b, the intake and compression strokes are proceeding simultaneously.

When transitioning from the state (d) above to the state (a), which is the next stroke, the piston 2 further moves toward the bottom dead center and first opens the scavenging port 23b of the air scavenging pump device and enters the pump chamber 18b. The compressed air is further transferred to the scavenging passage 22.
Then, the scavenging port 23a of the air-fuel mixture scavenging pump device is opened and the air-fuel mixture further compressed in the pump chamber 18a (or the air that becomes the air-fuel mixture in a later stroke) is transferred to the scavenging passage 22a. Scavenging is started through the rotor 11a,
2a and 12b and is located at the upper part of the crankcase 16, and at this time, the bulkhead rod 13a13b is connected to the rotor 11a,
llb is pushed in while sliding on the pivots 15a and 15b as support axes, and the air outlets 21a and 21b sides of the pump chambers 18a and 18b are in a state before the compression stroke is almost completed, and the pump chambers On the side of the intake ports 20a and 2Ob of the pistons 18a and 18b, the state is almost before the intake stroke is completed, and the piston 2 is at the bottom dead center and is in the scavenging state (a).

Furthermore, when transitioning from state (a) to state (b), which is the next stroke, the piston 2 moves from bottom dead center to top dead center, but at this time, the pump chambers 18a and 18b are in the compression stroke. As soon as the intake stroke is almost completed, first open the scavenging port 2.
3a and then close the scavenging port 23b to complete the scavenging.

As mentioned above, the casing rotor type scavenging pump device sequentially repeats the strokes (a), (b), (c), and (d), and at the same time, the power cylinder piston device is similar to a normal two-stroke gasoline engine. The cycle of scavenging, compression, ignition, and explosion is repeated.

In the above-mentioned embodiment, the structure and operation of the first embodiment employing the second, sixth and seventh embodiments of the present invention have been explained. The configuration and operation of the fifth embodiment will be explained.

5L from the above-mentioned FIG. 1 regarding the first embodiment of the present invention.
! ! 1, a reciprocating piston type pump structure obtained within the crankcase 16 by the operation of the reciprocating piston 2 of the power cylinder piston device is included as part of the scavenging pump device, and first, a set of This configuration is characterized in that air is scavenged from the power cylinder piston device by one or more sets of casing rotor type pump devices as mixture scavenging pump devices. , a circular crank arm 8b, which is the above-mentioned air casing rotor type scavenging pump device, an eccentric shaft 9b, a loader 11b, a bulkhead rod 13b, pivots 14b, 15b, a bulkhead rod holding member 17b, a pump chamber 18b, a casing 12b, 1
2d, an implementation in which the intake port 20b, the intake pipe 24b, the air outlet 21b, the scavenging passage 22b, and the scavenging port 23b are deleted, and the air is scavenged only by the remaining casing rotor type scavenging pump device for the air-fuel mixture. Examples include examples in which the air casing rotor type scavenging pump device is equipped with a fuel supply device and is used as a mixed gas scavenging pump device. This is almost the same as FIG. 5 of the first embodiment except that it is not.

FIG. 6 shows the second, third, and fourth embodiments of the present invention.
It is a right side sectional view of a cycle gasoline engine,
FIG. 7 is an exploded left sectional view in FIG. 6, and FIG.
To explain these embodiments with the help of figures, in the third, fourth and fifth embodiments, the air pressure is obtained within the crankcase 16 by the operation of the reciprocating piston 2 of the power cylinder piston device. A reciprocating piston pump structure is used as the scavenging pump device.

If the third embodiment is to be described as the second embodiment, the third embodiment! In this engine, a reciprocating piston type scavenging pump device, which is equipped with a carburetor in the intake pipe 24 shown in Fig. 6 and operates in the same way as a normal two-stroke gasoline engine, is mainly used as the air-fuel mixture scavenging pump device. As shown in FIG. 7, it has the same structure as the air casing rotor type scavenging pump device of the first embodiment, and
The construction is such that a casing rotor type scavenging pump device that performs similar operations is used as an air scavenging pump device.

To explain the fourth embodiment as a third embodiment, in the fourth embodiment, a carburetor is mainly provided in the intake pipe 24 shown in FIG. 6, and the operation is similar to that of a normal two-stroke gasoline engine. It has a reciprocating piston type scavenging pump device as a mixture scavenging pump device, which performs
A casing rotor scavenging device is provided with a carburetor in the intake pipe 24c shown in the figure, and has a structure similar to that of the casing rotor scavenging pump device for air-fuel mixture of the first embodiment described above, and performs the same operation. This configuration uses the Bon 1 device as a mixture scavenging pump device.

To explain the fifth embodiment as a fourth embodiment, in the fifth embodiment, a carburetor is mainly provided in the intake pipe 24c shown in FIG. A casing rotor type scavenging pump device having the same structure and operating in the same manner as the casing rotor type scavenging pump device for the air-fuel mixture is provided,
As shown in FIG. 6, the configuration is such that a reciprocating piston type scavenging pump device is used as an air scavenging pump device.

In the second, third, and fourth embodiments described above, a carburetor is used as the fuel supply device, but a fuel injection device similar to that of the first embodiment described above may also be used.

The configuration and operation of the first to seventh embodiments of the present invention have been explained above by citing the first to fourth embodiments and other embodiments, but the present invention is limited to the above embodiments. However, many modifications are possible within the scope of the present invention. For example, the rotor may have an elliptical shape that is not a perfect circle, or a perfect circular rotor with an eccentric axis of rotation may be adopted. settings, settings in which a one-way valve such as a reed valve is provided at the intake port of the casing rotor type scavenging pump device, settings in which the eccentric shaft is set at a phase angle other than 180 degrees with the crank pin, and the intake and outlet ports are the same as those described above. A setting in which the exhaust poppet valve is installed in the cylinder head in a different position from that in the example, a setting in which the exhaust poppet valve is installed for unifloated force bending, and a setting in which the connection part between the bulkhead rod and the bulkhead rod holding member is placed on the outlet side. Can be mentioned.

[Effects of the Invention] The effects of the two-stroke gasoline engine according to the present invention are listed below.

(1) By providing a casing rotor type scavenging pump device other than the reciprocating piston type scavenging pump device in the crankcase, it is possible to make the engine more compact than a separate scavenging pump device.

(2) In a casing rotor type scavenging pump device, the rotating shaft of the rotor also serves as the crankshaft of the power cylinder piston device, the eccentric shaft also serves as the crank arm, and the casing housing also serves as the crank case of the power cylinder piston device. This makes it possible to reduce the weight compared to a separate scavenging pump device.

(3) Compared to a separate type scavenging pump device, which is driven via gears or a toothed belt, the casing rotor type scavenging pump device does not require a transmission mechanism to drive the pump device. Less output loss occurs.

(4) Compared to a roots-type scavenging pump device, the amount of air scavenged per volume of the device is larger at the same rotation speed, and the manufacturing cost is lower, and the sliding parts with the vane casing are distributed in the vane-type scavenging pump device. It is more durable and the manufacturing cost is lower than when using a spiral scavenging pump device or a Wankel type compressor with two eccentrically arranged rotors manufactured by Beerburb of Germany as the scavenging pump device.

(5) The volume of the pump chamber can be set arbitrarily, increasing the air supply ratio and air supply efficiency, allowing sufficient scavenging, and improving output.

(6) In the first embodiment and the second embodiment, the pump chamber of the casing rotor type scavenging pump device and the crank chamber of the power cylinder piston device are independent and sealed, so lubricating oil is sealed in the crank chamber. Good lubrication can reduce wear on cylinder pistons, piston pins, connecting rod bearings, and crank pins, and there is no need to mix lubricating oil into the air-fuel mixture or air to be scavenged, spark plugs, and combustion chambers. and exhaust pipes are not adversely affected by lubricating oil.

(7) In the third, fourth, and fifth embodiments, scavenging, which was incomplete with only a reciprocating piston type scavenging pump device, is achieved by using a casing rotor type scavenging pump that is smaller than in the first and second embodiments. By providing this device, it is possible to increase the air supply ratio and air supply efficiency, and the output can be improved through sufficient scavenging.

(8) In the second, third, and fifth embodiments, the scavenging pump device for air and the scavenging pump device for mixture gas are independent, so that when scavenging, only air is discharged first, and then mixed. When expelling combustion residual gas from the exhaust port, it is possible to scavenge air by forming an air cushion between the mixture and the combustion residual gas, so that air can be exhausted first. It is possible to set the system so that the residual combustion gas is almost completely expelled from the exhaust port while the air mixed with the residual combustion gas is removed.In this case, the fresh air expelled from the exhaust port is almost only air. The fuel-containing air-fuel mixture is not expelled from the exhaust port, making it possible to prevent wasteful fuel consumption, as well as allowing for almost complete scavenging, thereby achieving both a reduction in fuel consumption and an increase in output.

(9) In the sixth embodiment, the effect of the above invention (8
) The same settings as above can be made, and the same effect can be obtained.In addition, during scavenging, the air and mixture discharged into the power cylinder can be swirled in two or more different directions. This makes it possible to scavenge air while the air is flowing, making it easy to form an air cushion between the air-fuel mixture and combustion residual gas, and by creating a vortex, the combustion rate is increased during the explosion and expansion stroke, which increases the combustion speed at high rotation speeds. Contributes to improved output.

(10) In the seventh embodiment, a means that requires driving force such as a rotary valve is not used as a scavenging timing adjustment mechanism, and only a scavenging port is provided to create a gap between the air-fuel mixture and combustion residual gas during scavenging. It is easy to form an air cushion, and it is possible to reduce fuel consumption and improve output, as well as reduce manufacturing costs and reduce size and weight.

[Brief explanation of the drawing]

FIG. 1 is a disassembled side sectional view of a two-stroke gasoline engine according to a first embodiment of the present invention, FIG. 2 is a partially cutaway plan view of FIG. 1, and FIG. 4 is a partially cutaway front view of FIG. 1;
FIG. 5 is a side sectional view showing the operating state of the two-stroke gasoline engine according to the first embodiment;
7 and 7 are side sectional views of two-stroke gasoline engines according to second, third and fourth embodiments of the present invention. "Explanation of symbols" 1...Cylinder 2...Piston,
3... Piston pin, 4... Connecting rod, 5... Crankshaft, 6...
Crank pin, 7a, 7b...Crank arm, 8a, 8b...Circular crank arm, 9a,
9b, 9c...Eccentric shaft, 10a, 10b
, 10c...Crank journal, 11a,
1 l b, 11 c-...rotor
12a, 12b, 12c, 12d, 12e, 12f・
-----Casing, 13a, 13b, 13c...
...Bulkhead rod, 14a, 14b, 14cm-
----- Pivot, 15a, 15b, 15c...
・Pivot, 16...Crankcase, 17a
, 17b, 17c... Bulkhead rod holding member, 1
8a, 18b, 18c...pump room, 19...
...Pump room, 20.20a, ? , Ob20 c
------Intake port, 21.21a, 21b, 21
c...--Outlet, 22.22a, 22b, 22c
...Scavenging passage, 23.23a, 23"b, 23
cm...Scavenging port, 24.24a, 24b, 24c.-
-----Intake pipe, 25...Exhaust port, 26...
...Cylinder block, 27...Cylinder head, 28...Exhaust pipe, 29...
Spark plug, 30... Cooling jacket, 32.
...Reed valve.

Claims (8)

[Claims] (1) At least one set of two-cycle power cylinder piston devices, and a circular crank arm whose crank pin side of the crank arm of the power cylinder piston device is circular so as to be slidable on the casing on the inner circumference of the crankcase, and the crank arm is provided with: a scavenging pump chamber sealed by the casing and the circular crank arm on the crank journal side of the scavenging pump chamber, forming a part of the structure of the crank arm and connecting the circular crank arm and the crank journal, and and an eccentric shaft set eccentrically with respect to the rotational center axis of the crank journal and provided with a rotor that can rotate around the periphery, one end of which is rotatably connected to the bulkhead rod holding member and the other end of which is rotatably connected to the rotor. A bulkhead rod that is movably connected and slides in the scavenging pump chamber, and the casing has a shape that slides on the rotor, and an intake port and an outlet are provided at the front and rear of the holding portion of the bulkhead rod. A two-stroke gasoline engine characterized by having a casing rotor type scavenging pump device. (2) The scavenging pump device does not include a reciprocating piston type pump structure obtained by the crank chamber of the power cylinder piston device as a part of the pump device, and the scavenging pump device does not include, as a part of the pump device, 2. The two-stroke gasoline engine according to claim 1, wherein air is scavenged by one or more sets of said casing rotor type pump devices as scavenging pump devices. (3) The scavenging pump device does not include a reciprocating piston pump structure obtained by the crank chamber of the power cylinder piston device as a part of the pump device, and the scavenging pump device does not include a reciprocating piston pump structure obtained by the crank chamber of the power cylinder piston device as a part of the pump device, Claim 1, wherein air is scavenged by one set of the casing rotor type pump device as a scavenging pump device and one set of the casing rotor type pump device as an air scavenging pump device. 2-stroke gasoline engine. (4) The scavenging pump device includes a reciprocating piston type pump structure obtained by the crank chamber of the power cylinder piston device as a mixture scavenging pump device, and the scavenging pump device for air is used for one set of the power cylinder piston devices. 2. The two-stroke gasoline engine according to claim 1, wherein the gas is scavenged by one or more sets of said casing rotor type pump devices. (5) The scavenging pump device includes a reciprocating piston pump structure obtained by the crank chamber of the power cylinder piston device as an air-fuel mixture scavenging pump device, and the scavenging pump device for the air-fuel mixture serves one set of the power cylinder piston devices. 2. The two-stroke gasoline engine according to claim 1, wherein air is scavenged by one or more sets of said casing rotor type pump devices. (6) The scavenging pump device includes a reciprocating piston type pump structure obtained by the crank chamber of the power cylinder piston device as an air scavenging pump device, and the scavenging pump device for air-fuel mixture is used for one set of the power cylinder piston devices. A two-stroke gasoline engine, characterized in that air is scavenged by one or more sets of the casing rotor type pump devices. (7) In the two-stroke gasoline engine according to claim 3, 4, or 6, the scavenging passage and the scavenging port of the mixture scavenging pump device, and the air scavenging pump A two-stroke gasoline engine characterized in that a scavenging passage and a scavenging port of the device are independent. (8) In the two-stroke gasoline engine according to claim 7, an opening on the piston top dead center side of the scavenging port of the air scavenging pump device is arranged so that the piston top dead center side opening of the scavenging port of the air-fuel mixture scavenging pump device is A two-stroke gasoline engine characterized by being disposed closer to the top dead center than the opening on the top dead center side of the piston.