DE112014001666T5 - Engine and portable work machine - Google Patents

Abstract

An engine capable of suppressing the decrease in a function causing unburned gas to remain in a combustion space is provided. An engine (12) has a combustion chamber (18) provided inside a cylinder, in which an exhaust port (32) connected to the combustion chamber (18) by a piston (22) located inside the cylinder (19) is moved back and forth, opened and closed. The engine (12) includes: a first exhaust passage (31) provided in the cylinder (19) and connected to the exhaust port (32); an opening (31a) formed at the downstream end of the first exhaust passage (31) in a discharging direction of a combustion gas discharged from the exhaust port (32); and a second exhaust passage (36) connected to the opening (31a) via a communication passage (41). The center E of the connection channel (41) in a cylinder axis direction and the center C (31a) in the cylinder axis direction are arranged at different positions in the cylinder axis direction.

Description

Technical area

The present invention relates to a motor used as a power source in a portable work machine such as a chainsaw or a cutting machine, and a portable work machine equipped with this motor.

Background Art

For most portable work machines, such as chainsaws and cutting machines, it is required that an engine serving as an energy source has high energy to be downsized and to be lightweight, and therefore, the use of a two-cycle engine as an energy source is very common. In the two-cycle engine, unburned gas is discharged via an exhaust port of a combustion chamber during the exhaust and purge processes in the engine, and the exhaust property deteriorates. Thus, to suppress the deterioration of the exhaust gas property in the two-stroke engine, a catalytic process, an air-driven purge method, an exhaust pulse method, etc. are adopted.

In the catalytic process, a catalyst is arranged in a discharge channel of the exhaust gas for purifying the exhaust gas. The air-driven flushing method is a method of introducing air into a flushing passage to the combustion chamber during the suction and purging of the engine before the unburned gas is discharged from the combustion chamber. Also, the exhaust pulse-purging method is a method that causes unburned gas to remain in the combustion chamber by propagating a pressure wave of a combustion gas discharged from the exhaust port to the exhaust port at a later stage of the exhaust process of the engine. Patent Document 1 describes an example of an engine having a structure that suppresses the deterioration of the exhaust property by the exhaust gas pulse washing method of the above-described methods, and an example of a portable engine-equipped work machine.

This engine described in the patent has an exhaust pipe provided downstream of the exhaust port and a branch pipe branching from the exhaust pipe. A downstream end of the exhaust pipe is connected to the outside of a muffler via an expansion chamber. In the engine described in Patent Literature 1, the exhaust gas is discharged from the combustion chamber to the exhaust pipe, pressure inside the expansion chamber propagates through the exhaust pipe immediately before the end of the exhaust process to the vicinity of the exhaust port, and the pressure reflected inside the branch pipe propagates through the exhaust pipe in the vicinity of the exhaust port. Thus, the pressure in the vicinity of the exhaust opening immediately before the end of the exhaust process increases and the unburned gas remains inside the combustion chamber, so that the deterioration of the exhaust gas property can be suppressed and the engine performance can be improved.

citations

Patent

• PTL 1: Japanese Laid-Open Patent Application, Publication no. 2012-67668

Summary of the invention

Technical problem

However, in order to suppress the outflow of the exhaust gas, it is necessary to further enhance the effect of the propagation of the pressure wave.

A preferred object of the present invention is to provide an engine that further improves a function that causes the unburned gas to remain in the combustion chamber and a portable work machine equipped with the engine.

the solution of the problem

An engine according to an embodiment is an engine having a combustion chamber provided inside a cylinder in which an exhaust port connected to the combustion chamber is closed and opened by a piston reciprocating inside the cylinder. The engine includes: a first exhaust passage provided in the cylinder and connected to the exhaust port; an opening formed at a downstream end of the first exhaust passage in a discharge direction of the combustion gas discharged from the exhaust opening, and a second exhaust passage connected to the opening via a connection passage, and a center of the connection passage in one Cylinder axis direction and a center of the opening in the cylinder axis direction are arranged at different locations to each other in the Zylinderachsrichtung.

A portable working machine according to another embodiment is a portable working machine comprising: an engine in which a combustion chamber is provided inside a cylinder, and an exhaust port connected to the combustion chamber, opened by a piston and is closed, which moves back and forth inside the cylinder, and a functional element, which is operated by energy, which is transmitted from the engine to the functional element. In the portable work machine, the engine includes: a first exhaust passage provided in the cylinder and connected to the exhaust port, an opening formed at a downstream end of the first exhaust passage in a discharge direction of the exhaust gas discharged from the exhaust gas combustion gas; and a second exhaust passage connected to the port via a communication passage, and a center of the communication passage in a cylinder axial direction and a center of the opening in the cylinder axial direction are located at different positions to each other in the cylinder axial direction.

Advantageous effect of the invention

According to an engine of the present invention, a pressure wave to be propagated from the second exhaust passage through the exhaust port communicating passage easily propagates toward the exhaust port, so that the decrease in function causing unburned gas to remain in the combustion chamber can be suppressed.

Brief description of the drawings

1 FIG. 10 is a front cross-sectional view explaining a portable work machine with a motor of the present invention. FIG.

2 FIG. 10 is an enlarged cross-sectional view explaining a construction example of the motor of the present invention. FIG.

3 is a sketch of the in 1 explained engine.

4 is an exploded view, partially a cylinder and a damper of the in 1 explained engine explained.

5 Fig. 12 is a schematic view explaining an operation of the engine of the present invention.

6 Fig. 12 is a schematic view explaining the operation of the engine of the present invention.

7 Fig. 12 is a schematic view explaining the operation of the engine of the present invention.

8th Fig. 12 is a schematic view explaining the operation of the engine of the present invention.

9 Fig. 12 is a schematic view explaining the operation of the engine of the present invention.

10 FIG. 10 is an enlarged cross-sectional view explaining another constructional example of the motor of the present invention. FIG.

11 FIG. 10 is an enlarged cross-sectional view explaining another constructional example of the motor of the present invention. FIG.

12 FIG. 10 is an enlarged cross-sectional view explaining another constructional example of the motor of the present invention. FIG.

13 FIG. 10 is an enlarged cross-sectional view explaining another constructional example of the motor of the present invention. FIG.

Description of embodiments

The embodiments for a motor of the present invention and the embodiments for a portable working machine equipped with the motor will be described in detail with reference to FIGS 1 to 4 described. 1 explains a cutting machine 10 working as the portable working machine, and the cutting machine 10 has a body case 11 , one inside the body 11 provided engine 12 and one outside the body 11 provided milling blade 13 on. The milling blade 13 corresponds to a functional element of the present invention. The milling blade 13 is worn so that it is able to turn, and is with a cover 14 for covering the cutter blade 13 intended. A front handle 15 and a rear handle 16 are on the body 11 attached externally, allowing a worker the cutting machine 10 with holding this front handle 15 and the rear handle 16 can lift. It should be noted that the rear handle 16 with a throttle 17 is provided. The throttle 17 is for adjusting the number of revolutions of the motor 12 provided by the worker.

The motor 12 is an internal combustion engine that burns a fuel-air mixture by mixing a fuel with air in a combustion chamber 18 is obtained to generate energy. The motor 12 indicates: a cylinder 19 , a damper 20 and a fuel delivery system 21 , Inside the cylinder 19 is a piston 22 provided so as to be able to reciprocate in a direction along a center line A. The direction along the center line A in the present invention is the cylinder axis direction. In 1 and 2 is the combustion chamber above the piston 22 inside the cylinder 19 educated. The cylinder 19 is also with a spark plug 23 equipped, leading to the combustion chamber 18 is exposed. Furthermore, a flushing opening 24 on an inner surface of the cylinder 19 trained, and the flushing opening 24 is via a flushing channel with a crank chamber 25 connected.

A crankcase 26 is meanwhile below the cylinder 19 provided, and the crankcase 25 is inside the crankcase 26 educated. A crankshaft 27 is for the crankcase 25 provided so as to be capable of rotation, and a connecting rod (connecting rod) 28 is from the inside of the cylinder 19 to the crank room 25 intended. At the connecting rod 28 is an end to the crankshaft 27 connected and the other end is with the piston 22 connected.

An air inlet pipe 29 is with the cylinder 19 connected, an air intake duct 30 inside the air inlet tube 29 is provided is with the crankcase 25 connected. The fuel delivery system 21 is higher upstream than the air intake passage 30 in a flow direction of the air, which is the air intake duct 30 is supplied, and the fuel-air mixture, which consists of the fuel and the air, is the crank chamber 25 through the air intake duct 30 fed. A first exhaust duct 31 is designed so that he has the cylinder 19 penetrates from its inner surface to its outer surface, and an exhaust port 32 is provided so that it is the first exhaust duct 31 connects with the interior of the cylinder.

The exhaust opening 32 is due to the movement of the piston 22 opened and closed. When the piston moves in a first direction of movement along the center line A in FIG 1 moves, ie when the piston 22 inside the cylinder 19 moved up, the exhaust port is 32 through the piston 22 closed. If, on the other hand, the piston 22 in a second direction of movement along the center line A in FIG 1 moves, ie when the piston is inside the cylinder 19 moved down, the exhaust port is 32 through the piston 22 open.

The damper 20 has an exhaust pipe 33 , a branch pipe 34 , a first expansion area 35 and a second expansion space 44 on. A second exhaust duct 36 is inside the exhaust pipe 33 educated. The second exhaust duct 36 is with a downstream end of the first exhaust passage 31 in a flow direction of an exhaust gas coming out of the exhaust port 32 in the first exhaust duct 31 is delivered, connected. A cross-sectional area of the first exhaust passage 31 is wider when the first exhaust passage closer to the second exhaust passage 36 is located in the flow direction of the exhaust gas. As in 4 is explained in a side view of the first exhaust passage 31 the opening shape of the first exhaust passage 31 approximately rectangular.

Also a center line B of the first exhaust duct 31 extends in a direction from top to bottom of the first exhaust passage so that it crosses the center line A at a non-right angle. The center line B is inclined in a direction in which the center line B is further away from a horizontal line when the center line B is closer to the second exhaust passage 36 in the flow direction of the exhaust gas inside the first exhaust passage 31 located. More specifically, in a state where the center line A of the piston is located 22 along a vertical line, a center C of the downstream end of the first exhaust passage 31 at a position lower than a center B of the exhaust passage 32 ,

The second exhaust duct 36 Meanwhile, it extends substantially horizontally from the particularly upstream end in the downstream direction in the flow direction of the exhaust gas, and then extends further downstream through a curved portion. The particularly downstream end of the second exhaust passage 36 is with the first expansion space 35 connected. A cross-sectional area of the second exhaust passage 36 is wider, since the second exhaust duct 36 in the flow direction of the exhaust gas closer to the first expansion space 35 located. Furthermore, the first expansion room 35 one of a wall element 37 and a partition 38 surrounded space. The partition 38 is with a third exhaust duct 39 fitted. The third exhaust duct 39 connects the first expansion room 35 with the second expansion room 44 , and the second expansion room 44 is via a fourth exhaust duct 45 in communication with the outside of the damper 20 ,

The motor 12 The present invention has a structural feature of a connecting part between cylinders 19 and dampers 20 on. The structure of the characteristic part of the engine will be described below step by step.

First Embodiment

A first embodiment of the engine will be described with reference to FIG 2 described. First is an opening 31a at the downstream end of the first exhaust passage 31 educated. Likewise, there is a seal 40 between the wall element 37 and the cylinder 40 , An opening 41 that the wall element 37 penetrates in a thickness direction, is provided, and an opening 42 that the seal 40 penetrating in a thickness direction is provided. The opening 41 corresponds to a connecting channel of the present invention, and the first exhaust passage 31 is with the second exhaust passage 36 about the second openings 41 and 42 connected. An opening 36a is at the downstream end of the second exhaust passage 36 educated. A cross-sectional area of the opening 41 is greater than the largest value of a cross-sectional area of a branch channel 34a , In this description, it should be noted that "upstream" and "downstream" are "upstream" and "downstream" in the direction of discharge from the exhaust port 32 mean discharged combustion gas.

Furthermore, a part of the exhaust pipe 33 in the first expansion room 35 arranged, and a flange 43 is at one end of an outer peripheral surface of the exhaust pipe 33 on the first exhaust channel 31 Page provided. The flange 43 is an annular body that extends from the outer peripheral surface of the exhaust pipe 33 protrudes outward, and the seal 40 and the wall element 37 lie between the flange 43 and the cylinder 19 , And a screw element is in a flange 43 trained hole is inserted and tightened, so that the exhaust pipe 43 , the wall element 37 and the seal 40 are fixed.

The forms of the opening 31a of the first exhaust passage 31 , the opening 42 the seal 40 and the opening 36a of the second exhaust passage are each substantially rectangular, and the four corners of each opening are bent. And the openings 31 . 36a and 42 are equal to each other in an opening width. Therefore, the opening width is a width in the cylindrical axis direction, that is, a width in the direction along the center line A. Also, the upper and lower edges of the openings 31a . 36a and 42 are in the same position relative to each other in the direction along the center line A. On the other hand, the opening width of the opening 41 in the wall element 37 is provided, narrower than the opening width of each of the openings 31a . 36a and 42 ,

Also located in the direction along the center line A, the upper edge of the opening 41 in the same position as a position of the top edge, at each of the openings 31 . 36a and 42 are formed. Furthermore, in the direction along the center line A is the lower edge 41b at the opening 41 is formed, at one of a position of the lower edge, at the respective openings 31a . 36a and 42 are formed, different position.

Ie. the lower edge 41b the opening 41 protrudes by a predetermined degree from the lower edge 31c the openings 31 and the lower edge of the second exhaust passage 36 upwards. And in the direction along the center line A are a center E of the opening 41 and a center C of the opening 31a arranged at different positions to each other. In a more specific explanation is a length from the center A to the top 32a the exhaust port 32 in the direction along the center line A shorter than a length from the center C to the top edge 32a , The top edge 32a the exhaust port 32 is an upper end of a part from which the exhaust opening 32 opens when the piston moves towards a top dead center. In this way, in the direction along the center line A, the center E is located higher than the center C.

Furthermore, inside the branch pipe 34 the branch channel 34a arranged. In the flow direction of the exhaust gas is the second exhaust passage 36 essentially horizontally in a region of the opening 36a of the second exhaust passage 36 to a part where the second exhaust duct 36 with the branch channel 34a is connected, arranged, and a center line F of the second exhaust passage 36 in this area is at the same level as that of the center C of the opening 31a of the first exhaust passage 31 , In other words, the center line B and the center line F intersect at the center C. Also, the center line F is at a position lower than the center E of the opening 41 ,

The branch channel 34a Branches from the second exhaust duct 36 and extends upward from the branch point. Then the branch channel extends 34a substantially horizontally, and then extending downwardly, and one end thereof opposite the second exhaust passage 36 is closed. A cross-sectional area of the branching channel 34a is from the second exhaust duct 36 to the closed end in the flow direction of the exhaust gas constant. Note that the end of the branch channel 34a opposite the second exhaust passage 36 may be closed, or it may be connected to the first expansion space via a small diameter hole. In other words, the branch channel 34a only have a structure in that the pressure wave from the second exhaust duct 36 propagated exhaust gas to the second exhaust passage 36 can be reflected.

In a case that is the engine 12 Being structured as described above, at the normal number of revolutions, such as 9000 rpm, the flow of the exhaust gas inside the engine becomes 12 and inside the damper 20 and a state of propagation of the pressure wave of the exhaust gas with respect to 1 . 2 and 5 to 9 described. As in 5 described, the piston moves 22 upward toward top dead center and closes both the purge port 24 as well as the exhaust port 32 , leaving a pressure inside the combustion chamber 18 rises and ignition control for the spark plug 23 to a predetermined time cycle is performed, resulting in a combustion of the air-fuel mixture in the combustion chamber 18 leads, ie it causes the air mixture exploded by the fuel mixture.

By the explosion method described above, a temperature and a pressure in the interior of the combustion chamber 18 high, and next to it the piston 22 moved down. When the exhaust port 32 is opened as in 6 explained by the movement down the piston 22 , the combustion gas is in the combustion chamber 18 through the exhaust port 32 and the first exhaust passage 31 to the second exhaust passage 36 issued. In this exhaust process, a positive pressure wave propagates to the second exhaust passage 36 and the branch channel 34a as indicated by an arrow G. When the positive pressure wave, extending from the second exhaust duct 36 up to the first expansion room 35 propagates, the most downstream end of the second exhaust passage 36 reached, reverses the positive pressure wave as a negative pressure wave, and propagates in a reverse direction, ie, in a direction by an arrow H as back flowing in the interior of the second exhaust passage 36 is indicated.

Thus, the positive pressure wave reaching into the branching channel reaches 34a propagates, the downstream end of the branch channel 34a and is reflected therefrom, and the reflected positive pressure wave propagates in a direction indicated by an arrow J as through the branch channel 34a in the direction of the second exhaust passage 36 returning home. During the operation described above, the purge port is 24 through the piston 22 closed.

When the flush opening 24 by further downward movement of the piston 22 , as in 7 is explained, opens a fuel-air mixture inside the crankcase 25 in the combustion chamber 18 over the flushing opening 24 In addition, the combustion gas is inside the combustion chamber 18 to the first exhaust duct 31 issued. Ie. an air intake process and a purge process are performed simultaneously. In the initial stage, in which the flushing opening 24 is opened, such a negative pressure wave in the direction indicated by the arrow H as returning and inside the second exhaust passage 36 propagating, and such a positive pressure wave in the direction indicated by the arrow J as reflected and inside the branch channel 36 breeding together. As a result, the back pressures of the exhaust port and the first exhaust passage 31 reduced.

From a period from the opening of the exhaust port 32 until a period of time that the piston 22 reaches a bottom dead center, the combustion gas is inside the combustion chamber 18 over the exhaust port 32 , the first exhaust duct 31 and the second exhaust passage 36 to the first expansion room 35 and next to it, combustion gas from the first expansion space 35 through the second expansion space 44 to the outside of the damper 20 issued.

If, on the other hand, the piston 22 reaches the bottom dead center, and reverses the direction of movement thereof, causing the piston to move upwards 22 leads to the flushing hole 24 close, the positive pressure wave is the inside of the first expansion space 35 remaining combustion gas to the second exhaust passage 36 propagated as indicated by an arrow K in 8th specified. And part of the positive pressure wave, extending to the second exhaust duct 36 propagates, planted after passing the branch point between the second exhaust passage 36 and the branch channel 34a in the branch channel 34 continue, and the rest will be in the direction of the first exhaust duct 31 propagated. As a result, the pressures in the first exhaust passage 31 and in the exhaust port 32 elevated.

The positive pressure wave leading to branch channel 34a is propagated at the downstream end of the branch channel 34a reflects and returns to the second exhaust duct 36 back. And from a time when the flushing hole 24 closed by the upward movement of the piston, until a time in which the exhaust port is closed, becomes part of the positive pressure wave, which is inside the branch channel 34a is reflected to the first exhaust passage 31 propagated, as with an arrow L in 9 specified. Therefore, the first exhaust duct 31 and the exhaust port 32 held in a highly pressurized state.

When the exhaust port 32 by further upward movement of the piston 22 is closed, the process continues to a compression process for compressing the fuel-air mixture inside the combustion chamber 18 and then returns to the above explosion process. Hereinafter, the explosion process, the exhaust process, the purging process, and the air suction process are repeated, so that the inversion force of the piston 22 in the torque of the crankshaft 27 is transferred. The motor 12 According to this embodiment, the so-called two-stroke cycle engine is one in which one cycle of the air suction process, scavenging process, compression process, explosion process and exhaust process takes place over the two strokes of the piston 22 be performed. And the torque of the crankshaft 27 becomes via an energy transfer mechanism on the milling blade 13 transferred so that the milling blade 13 rotates.

As described above, according to the engine 12 This embodiment of a period in which the exhaust port 24 is closed by upward movement of the piston until the period in which the exhaust port 32 closed, both the positive pressure wave, extending from the first expansion space 35 to the second exhaust duct 36 propagates, as well as the positive pressure wave, inside the branching channel 34 reflected and up to the second exhaust duct 36 is propagated until the first exhaust duct 31 and to the exhaust port 32 propagated so that the pressure in the exhaust port 32 can be kept high.

That is why a fresh gas, ie unburned gas, can be emitted from the combustion chamber 18 through the exhaust port 32 to the first exhaust duct 31 to flow, be pushed back into the combustion chamber. In other words, the injection of the unburned gas using the pressure pulsation of the exhaust gas inside the damper 20 suppressed. Therefore, the deterioration of the exhaust gas property in the engine can be suppressed, and the power of the engine can be improved.

More special is in the engine 12 this embodiment, the opening 41 between the first exhaust passage 31 and the second exhaust passage 36 provided, and the center of each opening 41 is in such a position that it is closer to the top edge 32a the exhaust port 32 as the center C of the opening 31a in the direction along the center line A lies. That is, when the piston 22 moved toward top dead center, is the distance between the part where the exhaust port 32 is open, and the center E of the opening 41 can be shortened as short as possible.

Therefore, it is for a direction of the second exhaust passage 36 to the first exhaust duct 31 propagating pressure wave easily, polarized and towards the part of the exhaust port 32 to be oriented towards where it is open. In other words, the bottom edge works 41b the opening 41 as a weir for easy concentration of the pressure wave on the exhaust port 32 , Therefore, in the engine 12 the power that causes unburned gas inside the combustion chamber 18 remains, further improved.

Also, the cross-sectional area of the opening 41 in the wall element 37 is provided within a range of 0.7 to 1.3 times the maximum value of the cross-sectional area of the exhaust port 32 be set. The maximum value of the cross-sectional area of the exhaust port 32 means the maximum value of the cross-sectional area obtained from the period in which the flushing opening 24 in the course of the upward movement of the piston 22 is closed until the period in which the exhaust port 32 is opened. And in the exhaust process of the engine 12 ie if the exhaust port 32 by the downward movement of the piston 22 is opened, is the cross-sectional area of the exhaust port 32 wider, as the piston 22 moved further down. For this reason, even if the cross-sectional area of the opening 41 is equal to or less than 1.0 times the maximum value of the cross-sectional area of the exhaust port 32 is set, the increase in the distribution resistance that is applied when the combustion gas is the opening 41 happens to be suppressed.

Also in the direction along the center line B of the first exhaust passage 31 and the center line F of the second exhaust passage 36 may be the distance from the exhaust port 32 to the lower edge 41b between 20 mm and 50 mm. This is due to the fact that the second exhaust duct 36 to the first exhaust duct 31 the propagated pressure wave is concentrated in the direction of the exhaust port 32 to flow.

The wall element 37 , which is a single component, also builds the first expansion chamber 35 and the opening 41 on. As a result, the increase in the number of components of the engine 12 be suppressed, and the increase in the manufacturing cost of the engine 12 can be suppressed, so that the cost-effective engine 12 can be provided.

Furthermore, in the flow direction of the exhaust gas, the branch channel 34a with the middle of the second exhaust passage 36 connected in its longitudinal direction, and therefore the damper 20 be reduced in size. Ie. around the engine 12 According to the present invention, downsizing in size or reducing a weight of the engine can be effected even if the lengths of the exhaust pipe 33 and the branch pipe 34 be shortened, even if the cross-sectional area and the volume of the second exhaust duct 36 be reduced, or even if the cross-sectional area and the volume of the branching channel are reduced, that the unburned gas inside the combustion chamber 18 remains. In other words, both the effect of reduced deterioration of the exhaust gas property of the engine 12 as well as the effect of reducing the size or reducing the weight of the engine 12 be achieved at the same time.

Also, an effective length of the second exhaust passage 36 and an effective length of branching channel 34a can be adjusted when the engine speed represents the normal number of revolutions, so that the pressure in the first expansion chamber 35 builds up, through the first exhaust duct 31 to the exhaust port 32 propagates immediately before the exhaust port 32 by upward movement of the piston 22 is closed.

Furthermore, it is preferred that the cross-sectional area of the opening 41 is greater than the cross-sectional area of the most upstream end of the branching channel 34a , Such a configuration can suppress a pressure loss caused by the distribution resistance when at the branch channel 34a reflected and reverse pressure wave through the opening 41 propagates to the exhaust port 32 to reach. Therefore, in the engine 12 the power that causes unburned gas inside the combustion chamber 18 remains to be further improved.

Second Embodiment

Next, a second embodiment of the engine will be described with reference to FIG 10 described. In the engine 12 from 10 corresponds to the opening 42 the connecting channel of the present invention, and the opening 31a of the first exhaust duct is with the opening 36a of the second exhaust passage 36 over the openings 42 and 41 connected. In the engine 12 who in 10 is explained, the center M of the opening 42 the seal 40 at one of the center C of the opening 31a different position in the direction along the center line A arranged. More specifically, in the direction along the center line A, a length from the center M of the opening is 42 the seal 40 to the top edge 32a the exhaust port 32 shorter than a length from the center C of the opening 31a to the top edge 32a the exhaust port 32 ,

In other words, in the direction along the center line A, a length from the midpoint M to an opened part of the exhaust port is 32 shorter than a length from the midpoint M to the opened part of the exhaust port 32 , Thus, in the direction along the center line A, the center M is located higher than the center C. In the engine 12 from 10 are also the center of the opening 41 and the center C of the opening 31a in the same position as each other in the direction along the center line A. Other structures of the engine 12 from 10 are the same as those of the engine 12 of the 1 to 3 ,

The function of the engine 12 from 10 is the same as the function of the engine 12 in the 5 to 9 is described. Also in the engine 12 from 10 is a length from the center M of the opening in the direction along the center line A 42 to the top edge 32a the exhaust port 32 shorter than a length from the center C to the top 32a the exhaust port 32 ,

As a result, from the period when the flushing opening 24 by the upward movement of the piston 22 is closed, until the time when the exhaust port is closed, the pressure wave passing through the second exhaust passage 36 to the exhaust port 32 propagates to the open part of the exhaust port 32 be concentrated, and therefore, the same effect as the effect of the first embodiment of the engine 12 to be obtained. Also, in the engine 12 from 10 the deterioration of the exhaust gas property by constructing an opening width of the in the gasket 40 provided opening 42 , and a position thereof in a height direction can be prevented. Therefore, the increase in the number of components can be prevented without providing a separate component. In the engine 12 from 10 It should be noted that structures other than the structures of the position and the opening width of the opening 42 the seal 40 can be engineered to be the same as those of the engine 12 from 2 , and it has the same effect as engine 12 from 2 can be obtained.

Third Embodiment

Next will be a third embodiment of the engine 12 with reference to 11 described. In the engine 12 who in 11 are explained, in the direction of the center line A, the lower edges of the openings 31a . 41 and 42 at the same position to each other, and the lower edge of the flange 43 protrudes from the top edges of the openings 31a . 41 and 42 upwards. Also is an end of the exhaust pipe 33 at the first exhaust channel 31 Side curved so that it is the bottom edge of the flange 43 bypasses. That is, the cross-sectional area of the opening 36a located at the upstream end of the second exhaust passage 36 is formed is smaller than the cross-sectional area of each of the openings 31a . 41 and 42 , This opening 36a corresponds to the connection channel of the present invention.

And in the direction along the center line A is the center N of the opening 36a at one of the center C of the opening 31a arranged in different position. More specifically, in the direction along the center line A, a length from the center N of the opening is 36a to the lower edge 32a the exhaust port 32 shorter than a length from the center C of the opening 31a to the lower edge 22a the exhaust port 32 , Thus, in the direction along the center line A, the center N is located higher than the center C. The further structures of the Motors 12 from 11 are the same as those of the engine 12 from 1 to 3 ,

The function of the engine 12 from 11 is the same as the function of the engine 12 who in 5 to 9 is described. In the engine 12 from 11 in the direction along the center line A is the length from the center N of the opening 36a to the top edge 32a the exhaust port 32 also shorter than the length from the center C of the opening 31a to the top edge 32a the exhaust port 32 , In other words, in the direction along the center line A, the distance between the opened part of the exhaust port is 32 and the center N set to be small, as short as possible.

As a result, from the period, from which the flushing opening 24 by the downward movement of the piston 22 is closed, up to the period from which the exhaust port is opened, through the opening 36a of the second exhaust passage 36 to the exhaust port 32 propagated pressure wave to the vicinity of the exhaust port 32 be concentrated, so that the same effect as the effect of the first embodiment of the engine 12 can be obtained. Also, in the engine 12 from 11 the deterioration of the exhaust property by constructing the opening width of the opening 36a and the position thereof in the height direction can be prevented. Therefore, the increase in the number of components can be prevented without providing a separate component. In the engine 12 from 11 may have structures other than the structures of the position and the opening width of the opening 36a be engineered to match those of the engine 12 from 2 are the same and the same effect as the engine 12 from 2 can be obtained.

Fourth Embodiment

Next, a fourth embodiment of the engine 12 with reference to 12 described. In the in 12 explained engine 12 are located in the direction of the center line A, the lower edges of the openings 31a . 41 and 42 in the same position to each other, and the lower edge of the flange 43 protrudes from the lower edges of the openings 31a . 41 and 42 up. Also bypasses one end of the exhaust pipe 43 at the first exhaust channel 31 -Page the lower edge of the flange 43 , In the engine 12 from 12 corresponds to this opening 36a the connection channel of the present invention. And in the direction along the center line A is the center N of the opening 36a at one of the center C of the opening 31a arranged in different positions. More specifically, in the direction along the center line A, a length from the opening is 36a to the top edge 32a the exhaust port 32 shorter than a length from the center N of the opening 31a to the top edge 32a the exhaust port 32 ,

Furthermore, in a part of the exhaust pipe 33 on the downstream side of its part with the flange attached thereto 43 an upper wall 36b essentially horizontal, and a bottom wall 36c extends so that it covers the wall like a tile. The bottom wall 36c is inclined in one direction, in which there is a gap between the bottom wall 36c and the upper wall 36b smaller is because the bottom wall 36c the opening 36a comes closer. More specifically, an inner surface of the lower wall 36c parallel to the center line B. The other structures of the engine 12 from 12 are the same as those of the engine 12 of the 1 to 3 ,

The function of the engine 12 from 12 is the same as the function of the engine 12 in the 5 to 9 is described. In the engine 12 from 12 is located in the direction along the center line A, the center N of the opening 36a also in one of the opening 31a different position. In other words, the distance in the direction along the center line A is between an opened part of the exhaust port 32 and set the center N to be smaller, as short as possible. Thus, in the direction along the center line A, the center N is located higher than the center C. As a result, from the period to which the flushing opening 24 is closed by the upward movement of the piston until the time when the exhaust port 32 is opened through the opening 36a of the second exhaust passage to the exhaust port 32 propagated pressure wave to the vicinity of the exhaust port 32 be concentrated, so that the same effect as the effect of the first embodiment of the engine 12 can be obtained.

Furthermore, in the engine 12 from 12 an inner surface of the upper wall 36b horizontally, while the bottom wall 36c inclined in the direction in which the gap between the lower wall 36c and the upper wall 36b gets smaller, because the bottom wall 36c the opening 36a comes closer. As a result, the through the opening 36a of the second exhaust passage 36 to the exhaust port 32 propagated pressure wave further to the vicinity of the exhaust port 32 be concentrated.

In the engine 12 from 12 The deterioration of the exhaust gas property can also be due to the construction of the shape of the flange 43 and the structure of the exhaust pipe 33 be prevented, so that the opening width of the opening 36a and the position thereof are set in the height direction. Therefore, the increase in the number of components can be prevented without a own component is provided. In the engine 12 from 12 It should be noted that structures other than the structures of the position of the opening width of the opening 36a can be constructed to be equal to those of the engine of 2 are, so that the same effect as that of the engine 12 from 2 can be obtained.

Fifth Embodiment

Next, a fifth embodiment of the engine will be described with reference to FIG 13 described. In the engine 12 from 12 who in 13 is explained, are in the direction along the center line A, the lower edges of the openings 31a . 36a and 42 in the same position to each other, a part of the wall element 37 projects up to a position closer to the center line F than the lower edges of the openings 31a . 36a and 42 to reach, and it is a towering part 37b provided, extending from the position by a curved part 37a extends in the direction of the first exhaust passage.

The towering part 37b is over the openings 31a and 42 arranged, and the opening 41 is above the towering part 37b educated. The curved part 37a has a curved surface 37c on, continuously from an inner surface of the opening 41 is trained. The towering part 37b is positioned so that it is lower than the center C of the opening 31a , and the center P of the opening 41 is at a position higher than the center C. In the engine 12 from 13 corresponds to the opening 41 the connection channel of the present invention. Other structures of the engine 12 from 13 are the same as those of the engine 12 of the 1 to 3 ,

The function of the engine 12 from 13 is the same as the function of the engine 12 in the 5 to 9 is described. In the engine 12 from 13 is located in the direction along the center line A, the center P of the opening 41 also at one of the center C of the opening 31a different position. That is, in a state before the exhaust port 32 by the movement of the piston 22 is closed, is a length from the midpoint P to an open part of the exhaust port 32 in the direction along the center line A shorter than a length from the center C to the opened part of the exhaust port 32 , Thus, in the direction along the center line A, the center P is located above the center C. As a result, from the time period at which the scavenging port is closed by the upward movement of the piston to the time at which the exhaust port is closed, the pressure wave passing through the opening 36 of the second exhaust passage 36 to the exhaust port 32 is propagated to the vicinity of the exhaust port 32 be concentrated, so that the same effect as the effect of the first embodiment of 12 can be obtained.

Furthermore, in the engine 12 from 13 the wall element 37 with the curved section 37a equipped, and the pressure wave is along a surface of the curved portion 37a propagated so that it follows a curved or arcuate shape. This can suppress a pressure loss caused when the pressure wave passes through the opening 36a of the second exhaust passage 36 to the exhaust port 32 is propagated.

In the engine 12 from 13 For example, the deterioration of the exhaust property can also be done by constructing the shape of the wall member 37 so that the opening width of the opening 41 and the position of the center P of the opening 41 in one direction along the center line A can be prevented. Therefore, the increase in the number of components can be prevented without providing a separate component. In the engine 12 from 13 It should be noted that structures other than the structure of the shape of the wall element 37 can be engineered to be the same as those of the engine 12 from 2 and it can have the same effect as the engine 12 from 2 to be obtained.

The motor and the portable working machine of the present invention are not limited to the above-described embodiments, and various modifications and changes may be made in the content of the scope of the present invention. For example, the engine of the present invention has not only a motor having such a structure that the center line A is arranged along the vertical line but also a motor having such a structure that the center line A is inclined from the vertical line. Also, the engine of the present invention not only has a motor having such a structure that the center line A and the center line B intersect each other at a non-right angle, but also a motor having such a structure that the center line A and the center line B intersect each other at a substantially right angle. The cross-sectional shapes of the openings and the cross-sectional shapes of the passageways in the present invention include an elliptical shape and a circular shape.

The portable working machine of the present invention is a power tool that transmits the power of a motor serving as a power source for a functional element, and the portable work machine includes not only the above-described cutting machine but also a blower, a hedge trimmer, a drill , a tiller, a chainsaw, a grass cutter, etc. The functional element of the grass cutter is a mowing blade. The functional element of the chain saw is a chain-shaped blade. The functional element of the blower is an impeller. The functional element of the cultivator is a soil-tilling blade. The functional element of the hedge trimmer is a knife. The functional element of the drill is a drill sheet. The functional element of the present invention comprises a functional element that rotates and a functional element that reciprocates and a functional element that circulates along a circular path.

Industrial application possibility

The present invention can be applied to a motor used as a power source in a portable work machine such as a chainsaw and a cutting machine.

Claims (11)

An engine having a combustion chamber provided inside a cylinder in which an exhaust port connected to the combustion chamber is opened and closed by a piston reciprocating inside the cylinder, the engine being characterized by the following is characterized: a first exhaust passage provided for the cylinder and connected to the exhaust port; an opening formed at a downstream end of the first exhaust passage in a discharge direction of a combustion gas discharged from the exhaust opening; and a second exhaust passage connected to the port via a communication passage, wherein the center of the communication passage in a cylinder axial direction and the center of the opening in the cylinder axial direction are arranged at different positions in the cylinder axial direction. The engine according to claim 1, wherein the center of the communication passage is located higher in the cylinder axis direction than the center of the opening. The engine of claim 1, wherein the engine is provided with a branch passage branching from the second exhaust passage. The engine of claim 3, wherein a cross-sectional area of the communication passage is larger than a cross-sectional area of the branch passage. An engine according to claim 1, comprising: an exhaust pipe with the second exhaust passage; an expansion space to which a combustion gas is discharged from the second exhaust passage; and a wall element that forms the expansion space, wherein the connecting channel is arranged in a part of the wall element between the cylinder and one end of the exhaust pipe. The motor of claim 5, wherein the wall member has a curved surface formed continuously from an inner surface of the connection channel. An engine according to claim 1, comprising: an exhaust pipe with the second exhaust passage; and a gasket located between an end of the exhaust pipe and the cylinder, wherein the connecting channel is provided for the seal. An engine according to claim 1, comprising: an exhaust pipe with the second exhaust passage; and a flange formed on the exhaust pipe and secured to the cylinder; wherein a part of the flange extends in the cylinder axis direction so as to form the connection channel. The engine according to claim 1, wherein a cross-sectional area of the communication passage is within a range of 0.7 to 1.3 times the maximum value for a cross-sectional area of the exhaust port. The engine according to claim 1, wherein the communication passage is provided at a position of 20mm to 60mm apart from the exhaust port in a direction of a length of the first exhaust passage. A portable working machine characterized by: an engine having a combustion chamber provided inside a cylinder, in which an exhaust port connected to the combustion chamber is opened by a piston reciprocating inside the cylinder and is closed; and a functional element operated by power transmitted to the functional element from the engine, the engine comprising: a first exhaust passage provided in the cylinder and connected to the exhaust port; an opening formed at a downstream end of the first exhaust passage in a discharging direction of a combustion gas discharged from the exhaust opening; and a second exhaust passage connected to the port via a communication passage, the center of the communication passage in a cylinder axial direction and the center of the opening in the cylinder axial direction at different positions are arranged to each other in the Zylinderachsrichtung.

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