JP2013530330A - Air supply device for 2-stroke engine - Google Patents

Abstract

  An air supply device (2) for a two-stroke engine, wherein the air supply device (2) is: an insulator-side mixture passage communicating with an intake port (5A) provided in an engine body (1) of a two-stroke engine An insulator (14) attached to the engine main body (1); a carburetor (15) attached to the insulator (14); and an air-fuel mixture side opening communicating with the carburetor-side air mixture passage (19) An air cleaner (16) attached to the carburetor (15); and a retention portion (29) for retaining blowback fuel returning from the mixture side opening (25) inside the air cleaner (16). And a pressure change in a crankcase chamber having a proximal end connected to the retention portion (29) and a distal end provided in the engine body (1). And a connection auxiliary passage portion spans.

Description

  The present invention relates to an air supply device for a two-stroke engine, and more particularly to an air supply device having a structure suitable for use of blowback fuel.

  Two-stroke engines are known in the art. In a two-stroke engine, one cycle of the engine includes an upward stroke and a downward stroke of the piston. While a new air-fuel mixture is introduced during the upward stroke, scavenging is performed during the downward stroke after ignition. During the downward stroke, some of the fuel or mixture can flow from the carburetor in the opposite direction to the engine and into the air cleaner. The fuel that flows into the air cleaner is generally called blowback fuel. Blowback fuel leads to fuel loss and clogs the filter elements in the air cleaner.

Various measures are being taken in this industry to reduce blowback fuel. One method is to provide a blocking plate in the air cleaner to prevent the flow of blowback fuel from the carburetor to the filter element, ensuring that the blowback fuel is utilized on the next upward stroke of the piston. .
Another well known method is to improve the structure of the piston reed valve.

However, when a prevention plate is provided, depending on the size of the prevention plate, air intake may be hindered and intake resistance may be caused, so the output of the two-stroke engine decreases.
Also, the structure can be more complicated and expensive to improve the structure of the piston reed valve. Furthermore, such a structure may be prone to failure.

  An object of the present invention is to provide an air supply device for a two-stroke engine that can use blowback fuel without waste without using a complicated structure or reducing the output of the two-stroke engine.

  The air supply device of the present invention is used for a two-stroke engine, and the air supply device has an insulator-side air-fuel mixture passage communicating with an intake port provided in the engine main body of the two-stroke engine. An insulator attached to the insulator, a carburetor-side mixture passage communicating with the insulator-side mixture passage, a carburetor attached to the insulator, and a mixture-side opening communicating with the carburetor-side mixture passage An air cleaner attached to the carburetor, and inside the air cleaner is provided with a staying part for staying blowback fuel returning from the mixture side opening, and a base end is connected to the staying part, And a crankcase case having a tip provided on the engine body. Wherein the auxiliary passage pressure variation is connected to a portion ranging in bar is provided.

Here, examples of the “part where the pressure fluctuation in the crankcase chamber reaches” include, for example, the crankcase chamber itself, a cylinder chamber provided in the engine body, a carburetor-side mixture passage of the carburetor, and an insulator side of the insulator An air-fuel mixture passage, a gap formed between the opposed surfaces of the carburetor and the air cleaner, the air-fuel mixture opening, and the like are conceivable.

  According to the present invention described above, the air supply device is connected to the stay portion provided in the air cleaner and the portion where the pressure in the crankcase chamber reaches the auxiliary passage, so that the blowback fuel staying on the air cleaner side is supported. The engine body can be sucked through the passage and can be used effectively without waste. Furthermore, since the blowback fuel accumulated in the staying portion is used reliably, the blowback fuel collected by the conventional prevention plate is reduced. Therefore, a large prevention plate is not necessary, and an increase in intake resistance can be prevented, thereby maintaining good engine performance.

In the air supply device of the present invention, when the tip of the auxiliary passage is connected to the gap between the air cleaner and the carburetor, or when connected to the mixture side opening of the air cleaner itself, the auxiliary passage is provided in the air cleaner. Is preferred.
In such a case, it is not necessary to expose the auxiliary passage to the outside, so that the structure can be simplified. Furthermore, since the auxiliary passage is not affected by the heat from the engine body, the durability of the auxiliary passage can be improved. In addition, since the length of the auxiliary passage may be short, the pressure loss in the auxiliary passage can be reduced, and the pressure difference between the staying portion and the connected part can be sufficiently applied, so that the staying portion can be blown back. Fuel can be sucked reliably.

In the air supply device of the present invention, it is preferable that the auxiliary passage is formed by a pipe.
In such a case, the staying part and the connection destination part can be easily connected. Furthermore, since it is easy to handle, for example, various parts such as a crankcase chamber and an insulator-side air-fuel mixture passage can be selected as the connection destination, and the degree of freedom in design is great.

In the air supply device of the present invention, it is preferable that at least a part of the auxiliary passage is covered with a heat insulating material.
In particular, in the case where the auxiliary passage is formed with a pipe or the like and is exposed outside, it is durable to cover the necessary part with a heat insulating material so as not to be affected by the heat from the heating part of the engine body. It is effective in improving

In the air supply device of the present invention, it is desirable that the staying portion is provided at a position where blowback fuel from the mixture-side opening drops and stays.
In such a case, a staying portion can be provided at a site where the blowback fuel is dropped by gravity, so that a complicated guide structure or the like for guiding the blowback fuel to the staying portion can be eliminated, and the structure is further simplified. Can be.

The air supply device of the present invention is preferably applied to a piston valve type two-stroke engine in which the intake port is opened and closed by a piston.
Since piston valve type engines tend to have more blowback fuel than reed valve type engines, the air supply device of the present invention is applied to piston valve type engines in order to make effective use of blowback fuel. When applied, the effect of the present invention is remarkable and more beneficial.

The air supply device of the present invention includes a choke plate that is provided so that the mixture side opening can be freely opened and closed, and the choke plate has the choke plate positioned in a state where the mixture side opening is open. It is desirable that an auxiliary passage forming portion that forms at least a part of the auxiliary passage is provided.
In such a case, the auxiliary passage is not formed when the air-fuel mixture side opening is closed by the choke plate. On the other hand, when the air-fuel mixture side opening is not closed by the choke plate but opens into the air cleaner body, an auxiliary passage is formed by the auxiliary passage forming portion of the choke plate, and the blowback fuel passes through the auxiliary passage. Can be recirculated. Therefore, in a state where the choke is applied, the negative pressure in the crankcase chamber does not act on the staying portion, and can be applied to the carburetor satisfactorily, so that the choke can be applied reliably.

In the air supply device of the present invention, the auxiliary passage is provided on the surface of the air cleaner main body and has one end communicating with the stay portion and one end provided on the surface of the air cleaner main body and one end of the air-fuel mixture. The auxiliary passage forming portion is formed by a second passage groove communicating with a side opening, and the auxiliary passage forming portion faces one of the first and second passage grooves and covers one surface of the choke plate. It is desirable that the connecting groove communicates the other ends of the first and second passage grooves.
In such a case, when the choke plate is moved to open the air-fuel mixture side opening, the first and second passage grooves communicate with each other through the connecting groove of the choke plate to form an auxiliary passage. Therefore, the blowback fuel accumulated in the staying portion can be reliably returned to the mixture side opening through the auxiliary passage.

In the air supply device of the present invention, it is preferable that the second communication groove is closed by the choke plate when the choke plate is positioned in a state where the air-fuel mixture side opening is closed.
In such a case, the second communication groove is similarly closed in a state where the air-fuel mixture side opening is closed by the choke plate. In the state in which the choke is applied, air does not enter from the second communication groove, and the choke can be reliably applied.

In the air supply device of the present invention, the auxiliary passage is a communication groove provided on the surface of the air cleaner body, one end communicating with the staying portion, and the other end communicating with the mixture side opening. And the auxiliary passage forming portion, and the auxiliary passage forming portion is preferably a part of the surface of the choke plate facing and covering the passage groove.
In such a case, since the continuous communication groove is provided on the air cleaner body side, the flow of blowback fuel in the communication groove (auxiliary passage) can be made smooth.

In the air supply device according to the aspect of the invention, it is preferable that the auxiliary passage has a tubular shape that is provided through the thick portion of the choke plate so as to communicate the stay portion and the mixture side opening.
In such a case, the auxiliary passage is tubular, and the periphery of the auxiliary passage is completely covered. Therefore, the negative pressure of the crankcase chamber can be reliably applied to the stay portion with little leakage, and the circulation of the blowback fuel can be improved.

In the air supply device of the present invention, the air cleaner body is provided with a pair of lock portions corresponding to the open / close positions of the mixture-side opening by the choke plate, and the choke plate is engaged with the lock portion. It is desirable that a matching holding part is provided.
This prevents the choke plate from shifting from the open / closed position due to vibrations of the engine or other components. Choke plate misalignment can interfere with engine operation. For example, if the choke plate shifts from the open position to the closed position, the air supply to the engine may be interrupted and the engine may be stopped halfway.

In the air supply device of the present invention, the pair of lock portions are provided on the end side of the curved rib along the opening / closing locus of the choke plate, and the upper end side of the curved rib is positioned in the vicinity of the mixture-side opening. In addition, it is desirable that the lower end side is located in the vicinity of the staying portion, and is a guide portion that guides blowback fuel from the mixture side opening to the staying portion side.
In such a case, the blowback fuel from the air-fuel mixture side opening is reliably guided by the lower staying part through the guide part formed by the curved rib, and the circulation from the staying part can be improved.

1 is a cross-sectional view showing an engine provided with an air supply device according to a first embodiment of the present invention. Sectional drawing which shows the engine provided with the air supply apparatus which concerns on 2nd Embodiment of this invention. Sectional drawing which shows the engine provided with the air supply apparatus which concerns on 3rd Embodiment of this invention. Sectional drawing which shows the engine provided with the air supply apparatus which concerns on 4th Embodiment of this invention. Sectional drawing which shows the engine provided with the air supply apparatus which concerns on 5th Embodiment of this invention. Sectional drawing which shows the engine provided with the air supply apparatus which concerns on 6th Embodiment of this invention. Sectional drawing of a 2-stroke engine provided with the air supply apparatus which concerns on 7th Embodiment of this invention. The front view of the air cleaner based on 7th Embodiment of this invention in which a chalk plate is a closed position. The front view of the air cleaner based on 7th Embodiment of this invention in which a chalk plate is an open position. The rear view of the chalk plate which concerns on 7th Embodiment of this invention. FIG. 9B is a cross-sectional view of the choke plate along the axis A-A ′ in FIG. 9A. The front view of the air cleaner which has a single auxiliary channel | path based on 8th Embodiment of this invention. The front view of the air cleaner which has the auxiliary | assistant channel | path with which a chalk plate is equipped based on 9th Embodiment of this invention. FIG. 11B is a cross-sectional view of the air cleaner along axis B-B ′ in FIG. 11A.

[First Embodiment]
A first embodiment of the present invention will be described below with reference to FIG. In addition, about 2nd Embodiment onward mentioned later, suppose that the same code | symbol is used about the same structural member as 1st Embodiment, and description of those structural members in 2nd Embodiment or later is abbreviate | omitted or simplified.

  In FIG. 1, a two-stroke engine (hereinafter simply referred to as an engine) of the present embodiment is provided with an engine body 1, an air supply device 2 provided on the intake side of the engine body 1, and an exhaust side of the engine body 1. The exhaust muffler 3 is provided.

  The engine body 1 includes a crankcase 4 and a cylinder 5 attached to the upper part of the crankcase 4. A crankshaft 7 is rotatably supported in a crankcase chamber 6 provided in the crankcase 4. A piston 9 is slidably accommodated in a cylinder chamber 8 provided in the cylinder 5. The piston pin 9A of the piston 9 and the crankshaft 7 are connected by a connecting rod 10.

  The crankcase 4 of the present embodiment is a two-divided type composed of a pair of case members. Each case member is connected to each other along the axial direction of the crankshaft 7. In FIG. 1, one case member is shown. However, the crankcase 4 may have a two-part structure in which the crankshaft 7 is sandwiched from above and below in the drawing. Such a crankcase chamber 6 of the crankcase 4 communicates with the cylinder chamber 8 below the piston 9.

  In the cylinder 5, an intake port 5 </ b> A for drawing the air-fuel mixture is provided on the cylinder wall on the side where the air supply device 2 is attached. An exhaust port 5B for exhausting exhaust gas is provided on the cylinder wall on the side where the exhaust muffler 3 is attached.

  Although not shown, a transfer passage is provided in the cylinder wall for communicating the crankcase chamber 6 with a conversion chamber (combustion chamber) 11 above the piston 9, and the upper end of the transfer passage serves as a transfer port. 11 is open.

  Furthermore, the engine of the present embodiment is a strato charge (stratified scavenging) type. Therefore, an air port 5C for drawing fresh air is provided above the intake port 5A on the cylinder wall. The air port 5 </ b> C is bifurcated to open at two locations with respect to the conversion chamber 11. In the final stage of the upward stroke of the piston 9, the air port 5C communicates with a concave communication groove (not shown) provided on the outer periphery of the piston 9, thereby communicating with the transfer port.

  The piston 9 functions as a piston valve that opens and closes the intake port 5A, the exhaust port 5B, the air port 5C, and the transfer port. That is, the piston 9 opens the intake port 5A and the air port 5C at the end of the upward stroke (the state shown in FIG. 1). Therefore, a new air-fuel mixture is drawn from the air supply device 2 side due to the negative pressure in the crankcase chamber 6 and is filled into the crankcase chamber 6 through the lower side of the cylinder chamber 8.

  At the same time, fresh air from the air supply device 2 side is drawn in from the air port 5C, and is filled from the transfer port side to the upper side in the transfer passage (side closer to the transfer port) via the communication groove of the piston 9. The

  When ignition in the spark chamber 12 is performed by the ignition of the spark plug 12 and the piston 9 turns to a downward stroke, the piston 9 opens the exhaust port 5B, while closing the air port 5C and the intake port 5A.

  When the conversion chamber 11 is opened by the exhaust port 5B and the inside of the crankcase chamber 6 is pressurized by the downward stroke of the piston 9, the air-fuel mixture in the crankcase chamber 6 is converted through the transfer passage. While being supplied to the chamber 11 side, the combustion gas in the conversion chamber 11 is scavenged and discharged from the exhaust port 5B as combustion gas.

  At this time, since the fresh air is preliminarily filled near the transfer port of the transfer passage, first, when scavenging the combustion gas, the fresh air scavenges the combustion gas as the leading air. Therefore, in the scavenging stroke, the unburned fuel contained in the air-fuel mixture becomes difficult to blow out from the exhaust port 5B, and the emission can be reduced.

  By the way, in the two-stroke engine, the air-fuel mixture may be returned to the opposite side with the downward stroke of the piston 9 (blowback). When the piston valve is used as in this embodiment, the time lag until the intake port 5A is closed is larger than when the reed valve is used. It tends to increase.

  Therefore, in the present embodiment, a structure for reliably using the blowback fuel without wasting it is employed in the air supply device 2. Below, the air supply apparatus 2 is demonstrated in detail.

  The air supply device 2 includes an insulator 14 attached to the cylinder 5 of the engine body 1, a carburetor 15 attached to the insulator 14, and an air cleaner 16 attached to the carburetor 15.

  The insulator 14 is made of a synthetic resin and has a heat insulating property, and suppresses the heat on the engine body 1 side from being transmitted to the carburetor 15. The insulator 14 is provided with an insulator-side air-fuel mixture passage 17 that communicates with the intake port 5 </ b> A of the cylinder 5, and an insulator-side air passage 18 that communicates with the air port 5 </ b> C of the cylinder 5.

  The carburetor 15 is used for a stratified scavenging engine, and has a carburetor-side mixture passage 19 that communicates with an insulator-side mixture passage 17 of the insulator 14 and a carburetor-side air passage 20 that communicates with an insulator-side air passage 18. ing. A main jet (not shown) is provided in the carburetor-side mixture passage 19. Fuel is drawn from the main jet by the negative pressure in the crankcase chamber 6. This fuel is mixed with intake air that is fresh air from the air cleaner 16 side to generate an air-fuel mixture.

  In each of the passages 19 and 20 of the carburetor 15, butterfly valves 21 and 22 that open and close in conjunction with the operation of the accelerator lever are provided. The intake air flow rate in the carburetor side air-fuel mixture passage 19 and the air flow rate in the carburetor side air passage 20 are adjusted according to the opening degree of these butterfly valves 21 and 22 according to the driving state of the engine.

  In addition, you may employ | adopt a rotary valve instead of the butterfly valves 21 and 22 in this embodiment. As the rotary valve, one having a single cylindrical valve body penetrating each of the passages 19 and 20 can be adopted. It is possible to adjust the flow rate in each of the passages 19 and 20 by rotating one valve body in conjunction with the accelerator lever.

  The air cleaner 16 includes a case 23 attached to the carburetor 15, a cover 24 attached to the case 23, and a filter element (not shown) disposed in the case 23 and sandwiched between the cover 24.

  The case 23 is provided with an air-fuel mixture-side opening 25 that communicates with the carburetor-side air-fuel mixture passage 19 of the carburetor 15 and an air-side opening 26 that communicates with the carburetor-side air passage 20. Fresh air that has passed through the filter element is supplied to both openings 25 and 26. As described above, the intake air that is fresh air drawn from the mixture side opening 25 is mixed with fuel in the carburetor side mixture passage 19 and sent to the intake port 5A as the mixture. Fresh air drawn from the air-side opening 26 passes through the carburetor-side air passage 20 and the insulator-side air passage 18 and is sent to the air port 5C.

  Further, a prevention plate 27 is attached at a position facing the mixture side opening 25 in the case 23 to collect blowback fuel and prevent the blowback fuel from being sprayed to the filter element side. The prevention plate 27 is a metal plate-like member and has a size that does not hinder the intake of the intake air sucked from the mixture side opening 25. A choke plate is provided between the prevention plate 27 and the gas mixture side opening 25 so as to be able to advance and retreat, and the openings 25 and 26 may be appropriately opened and closed. Is omitted.

  A collecting portion 28 for collecting blowback fuel is provided on the prevention plate 27 so as to project toward the mixture side opening 25. The blowback fuel collected by the collection unit 28 is again sucked into the carburetor 15 side together with the intake air, and is used for air-fuel mixture generation. However, such a prevention plate 27 may be provided as necessary and can be omitted.

  Incidentally, even in the present embodiment in which the prevention plate 27 is provided, it is difficult to completely collect the blowback fuel by the prevention plate 27. The blowback fuel that has not been collected drops downward due to its gravity and stays in the staying portion 29 provided on the bottom side in the case 23. The air supply device 2 according to the present embodiment can use the blowback fuel retained in the retention portion 29.

  A through hole 30 that communicates the inside and outside of the case 23 is provided on the bottom surface of the case 23 that forms the staying portion 29. A base end of a resin pipe 31 made of a material that does not easily deteriorate with respect to fuel is inserted into the through hole 30 from the outside and connected to the staying portion 29. The tip of the pipe 31 is inserted into a through hole 32 provided in the crankcase 4 and connected to the crankcase chamber 6. Therefore, the stay part 29 and the crankcase chamber 6 are in direct communication with each other by the pipe 31.

  A connecting portion between the pipe 31 and each of the through holes 30 and 32 is sealed with a seal 33. Reference numeral 34 in FIG. 1 is a heat insulating material covering the middle of the pipe 31. The region covered with the heat insulating material 34 may be determined so as to protect the pipe 31 from the heating portion of the engine body 1 in consideration of the route of the pipe 31 and the like, and is not limited to the illustrated region.

  Such a pipe 31 forms an auxiliary passage through which blowback fuel is sent from the staying portion 29 into the crankcase chamber 6. The blowback fuel staying in the staying portion 29 is sucked through the pipe 31 to the crankcase chamber 6 side where the pressure becomes lower due to the pressure difference generated between the staying portion 29 and the crankcase chamber 6.

  At this time, since the amount of fuel sucked as blowback fuel is small compared to the amount of fuel flowing into the crankcase chamber 6 from the intake port 5A, the engine performance is greatly influenced by the addition of blowback fuel. Never happen.

  Further, the inner diameter of the pipe 31 is sufficiently small, and the opening area opened in the crankcase chamber 6 is also small. For this reason, even when the piston 9 turns to a downward stroke, the air-fuel mixture in the crankcase chamber 6 hardly enters the pipe 31 and is hardly returned to the staying portion 29 again.

According to the above embodiment, the following effects are obtained.
The air supply device 2 is provided with a pipe 31 as an auxiliary passage for communicating between a staying portion 29 provided in the case 23 of the air cleaner 16 and the crankcase chamber 6. Therefore, even in an engine employing a piston valve, the blowback fuel is sucked into the engine body 1 by the pipe 31 having a simpler structure without improving the piston 9 or the cylinder 5 side to a complicated structure. it can.

  Furthermore, since the blowback fuel accumulated in the staying portion 29 is used reliably, the blowback fuel collected by the conventional prevention plate is reduced. For this reason, it is not necessary to employ the large prevention plate 27 and may be omitted depending on circumstances. Therefore, an increase in intake resistance due to the prevention plate 27 can be prevented, and the engine performance can be maintained well.

[Second Embodiment]
FIG. 2 shows a second embodiment of the present invention. In the present embodiment, the tip of the pipe 31 is inserted into a through hole 35 provided in the cylinder 5 and connected to the cylinder chamber 8. The through hole 35 is bent in the cylinder wall, and communicates the inside and outside of the cylinder chamber 8 below the piston 9. In addition, the through-hole 35 may be provided in the position opened and closed during the stroke of the piston 9, and may be provided in the position always open | released. Further, the through hole 35 may be provided in a horizontal straight line at the overlapping portion so as to penetrate both the cylinder 5 and the crankcase 4.

  Also in this embodiment, the blowback fuel staying in the staying portion 29 on the air cleaner 16 side can be sucked into the crankcase chamber 6 through the cylinder chamber 8, and the object of the present invention can be achieved.

[Third Embodiment]
FIG. 3 shows a third embodiment of the present invention. In the present embodiment, the tip of the pipe 31 is inserted into a through hole 36 provided on the lower side of the carburetor 15 and connected to the carburetor-side mixture passage 19. The through-hole 36 is provided vertically so as to communicate the carburetor-side mixture passage 19 with the outside. However, the lower side of the carburetor 15 often has a pump mechanism that draws fuel from the fuel tank, and it may be difficult to provide the through hole 36. In such a case, the through hole 36 may be provided on the side of the carburetor 15.
Also in this embodiment, the blowback fuel in the staying portion 29 can be used without waste by sucking the blowback fuel into the carburetor-side mixture passage 19 side.

[Fourth Embodiment]
FIG. 4 shows a fourth embodiment of the present invention. In the present embodiment, the tip of the pipe 31 is inserted into a through hole 37 provided on the lower side of the insulator 14 and connected to the insulator-side air-fuel mixture passage 17. The through-hole 37 is a vertical hole that allows the insulator-side air-fuel mixture passage 17 to communicate with the outside. However, as in the third embodiment, when it is inconvenient to provide the through hole 37 on the lower side of the insulator 14 for some reason, the through hole 37 may be provided on the side portion or the upper portion of the insulator 14.

[Fifth Embodiment]
In the fifth embodiment of the present invention shown in FIG. 5, the carburetor 15 and the case 23 of the air cleaner 16 are in contact with each other via an O-ring 38 provided on the carburetor 15 side, and there is a gap between the opposing surfaces. 39 is formed. A through-hole 40 that allows the inside of the case 23 and the gap 39 to communicate with each other is provided in a wall of the case 23 that faces the carburetor 15. The position where the through hole 40 is provided is the inner side surrounded by the O-ring 38. The proximal end of the pipe 31 serving as an auxiliary passage is located in the staying portion 29, and the distal end is inserted into the through hole 40 and connected to the gap 39. Thus, the N pipe 31 is disposed in the case 23 and is fixed by an appropriate fixing means such as an adhesive.

  In the present embodiment, since the gap 39 communicates with each of the passages 19 and 20, negative pressure also acts on the gap 39. Therefore, the blowback fuel in the staying part 29 is sucked into the gap 39 through the pipe 31 due to the pressure difference between the staying part 29 and the gap 39. The sucked blowback fuel flows into the passages 19 and 20 and is supplied to the engine body 1 for use.

  Here, part of the blowback fuel is also supplied to the air port 5C via the carburetor-side air passage 20 and the insulator-side air passage 18, and the blowback fuel is mixed into the leading air. However, since the amount of the mixture is small, even if the fuel blows through with the leading air during scavenging, it does not hinder the emission reduction. In addition, in this embodiment, illustration of the prevention board 27 (FIGS. 1-4) is abbreviate | omitted, but application of the prevention board 27 is arbitrary. The same applies to the following sixth embodiment.

[Sixth Embodiment]
In the sixth embodiment shown in FIG. 6, in the case 23, the proximal end side of the pipe 31 is located in the staying portion 29, and the distal end side is a notch portion 42 provided in the cylindrical rib 41 around the mixture side opening 25. Is inserted and positioned, and is connected to the mixture side opening 25. Also in this embodiment, the pipe 31 is fixed in the case 23 by appropriate fixing means such as an adhesive. However, the notch portion 42 of the cylindrical rib 41 is not necessary when the tip of the pipe 31 can be sufficiently positioned by fixing the pipe with an adhesive or the like.

  The blowback fuel is sucked up through the pipe 31 by the action of negative pressure from the carburetor-side air-fuel mixture passage 19 and sucked out from the tip thereof. The sucked-out blowback fuel is mixed with intake air and sucked into the carburetor-side mixture passage 19 side, and is supplied to the engine body 1 together with the mixture generated in the carburetor-side mixture passage 19 for use. Is done.

[Seventh Embodiment]
FIG. 7 is a cross-sectional view of a two-stroke engine 100 including an air supply device 102 according to a seventh embodiment of the present invention. The two-stroke engine 100 (hereinafter referred to as “engine 100”) is a stratified scavenging type that can be used for various power systems such as a chain saw, a line trimmer, a hedge trimmer, a lawn mower, an outboard motor, and an automobile. However, it is not limited to these. In addition, any suitable size, shape or type of member or material can be used.

  As shown in FIG. 7, the engine 100 includes a cylinder block 104 and a crankcase 106. The cylinder block 104 includes one cylinder 108 having a cylinder chamber 110. In other embodiments of the present invention, the cylinder block 104 may have two or more cylinders (not shown). The crankcase 106 has a crankcase chamber 112 that houses the crankshaft 114. In general, the piston 116 reciprocates within the cylinder chamber 110 of the cylinder 108 and is connected to the crankshaft 114 via a connecting rod 118. Further, the cylinder 108 has an intake port 120, an exhaust port 122, and one or more scavenging ports (not shown). Alternatively, the intake port 120 may be a part of the crankcase 106. An exhaust muffler 124 is also attached to the exhaust port 122 to reduce exhaust gas noise. The scavenging ports can be arranged at different positions on the cylinder 108. In one embodiment of the present invention, the intake port 120 and / or one or more scavenging ports may have a reed valve (not shown) that regulates fluid flow. Further, the crankcase chamber 112 and the inside of the cylinder 108 may be connected by one or more engine scavenging passages (not shown). In one embodiment of the present invention, the scavenging port opens into a corresponding scavenging passage of engine 100. Further, a spark plug 126 is also provided for igniting the air-fuel mixture inside the cylinder 108.

  As shown in FIG. 7, the air supply device 102 supplies air-fuel mixture and scavenging air to the engine body via the intake port 120 and the scavenging port, respectively. The air supply device 102 includes an air cleaner 128, a carburetor 130, and an insulator 132. The air cleaner 128 includes an air cleaner body 134 that at least partially surrounds a chamber 136 having a mixture side opening 138 and an air side opening 140.

  Further, the air cleaner 128 includes a metal prevention plate 141 and one or more filter elements (not shown). The one or more filter elements have the function of collecting particulate matter and / or any liquid in the outside air before air is introduced into the carburetor 130. The prevention plate 141 may be a prevention plate that is attached to the air cleaner body 134 by various means such as, but not limited to, mechanical fasteners, welding, brazing, and adhesives. The prevention plate 141 substantially prevents the blowback fuel from flowing out from the chamber 136 toward the filter element, and allows the blowback fuel to return to the crankcase chamber 112 through an auxiliary passage described later. Furthermore, the prevention plate 141 also substantially prevents clogging caused by blowback fuel flowing into the filter element.

  Further, a cover (not shown) may be attached to the air cleaner body 134. The air cleaner 128 also includes a choke plate (not shown) that can move between an open position and a closed position. The provision of the choke plate substantially prevents air flow through the mixture side opening 138 and / or the air side opening 140 in the closed position. Further, the air cleaner 128 further includes at least one auxiliary passage (not shown) that at least partially connects a portion of the chamber 136 to the mixture side opening 138 and / or the air side opening 140. The auxiliary passage is formed in the air cleaner body 134 as described with reference to FIGS. 8A and 8B.

  As shown in FIG. 7, the carburetor 130 has a carburetor-side air-fuel mixture passage 142 and a carburetor-side air passage 144. The air-fuel mixture-side opening 138 and the air-side opening 140 of the air cleaner 128 communicate with the carburetor-side air-fuel mixture passage 142 and the carburetor-side air passage 144, respectively. Further, as shown in FIG. 7, the carburetor-side mixture passage 142 and the carburetor-side air passage 144 are connected to the insulator-side mixture passage 146 and the insulator-side air passage 148 of the insulator 132, respectively. Furthermore, the insulator-side air-fuel mixture passage 146 and the insulator-side air passage 148 are connected to the intake port 120 and the scavenging port of the engine body, respectively.

  When the engine 100 is in operation, at least a part of the blowback fuel is collected by gravity in a stay part (described later), one or more guide parts (described later), the prevention plate 141, or a combination thereof. At least a part of the blowback fuel returns to the crankcase chamber 112 through the auxiliary passage due to the difference between the pressure in the chamber 136 of the air cleaner 128 and the pressure in the crankcase chamber 112. However, the blowback fuel may return to any other portion of engine 100 (eg, cylinder 108) at a pressure other than the pressure in chamber 136 of air cleaner 128.

  For those skilled in the art, the details of the engine 100 and the air supply device 102 described above are merely illustrative, and the engine 100 and the air supply device 102 may have different structures without departing from the scope of the present invention. It will be clear. For example, in each embodiment of the present invention, the engine 100 may not use scavenging air to discharge the exhaust gas. In such a case, the scavenging port, the insulator side air passage 148, the carburetor side air passage 144, and the air side opening 140 of the air cleaner 128 may be omitted. Alternatively, in another embodiment of the present invention, there may be a plurality of scavenging air flow paths from the air cleaner 128 to the engine 100. In some embodiments of the present invention, a single channel of scavenging air may branch into two or more channels.

  8A and 8B show the air cleaner 128 with the prevention plate 141 removed as a seventh embodiment of the present invention. Further, FIGS. 8A and 8B show the choke plate 202 in each closed and open position. As illustrated in FIGS. 8A and 8B, the choke plate 202 is plate-shaped. The choke plate 202 has a first surface (not shown in FIGS. 8A and 8B) facing the mixture side opening 138 and the air side opening 140 in the closed position. The second surface 203 is the opposite side of the first surface. Further, the choke plate 202 includes a first block part 204, a second block part 206, an operation part 208, a holding part 210, and an extension part 212. The first block portion 204 and the second block portion 206 are configured to substantially prevent air flow through the mixture side opening 138 and the air side opening 140, respectively, in the closed position. Further, the operating portion 208 is connected to the operating lever 214 by a fastening member 216. The fastening member 216 may be a screw that engages with a screw portion (not shown) of the corresponding operation lever 214. However, in another embodiment of the present invention, the operating portion 208 and the operating lever 214 may be connected by an adhesive or may be integrally formed. As shown in FIGS. 8A and 8B, the actuating portion 208 and the actuating lever 214 pivot together about an axis substantially perpendicular to the paper surface. In this manner, the choke plate 202 moves between the closed position and the open position by pivoting the actuating lever 214. The actuating lever 214 may be manually actuated or automatically actuated within the scope of the present invention. It will also be apparent to those skilled in the art that the choke plate 202 may have any shape without departing from the scope of the present invention. Further, the choke plate 202 may be actuated in other ways such as, but not limited to, electromagnetic or pneumatic.

  As shown in FIGS. 8A and 8B, the air cleaner body 134 has a guide 218 that facilitates the flow of blowback fuel to the stay 220 of the chamber 136 by gravity. The stay part 220 is located in a lower region of the chamber 136, and more specifically, is located adjacent to a lower part of the guide part 218. However, the staying portion 220 may be any other region or portion of the air cleaner 128 as long as it is within the scope of the present invention. As shown in FIGS. 8A and 8B, the guide 218 is a curved rib formed in the body 134 and protruding into the chamber 136. That is, the upper end side of the curved rib is located in the vicinity of the mixture side opening 138 and the lower end side is located in the vicinity of the staying part 220, so that the blowback fuel from the mixture side opening 138 can be guided to the staying part 110. It is. Note that the guide portion 218 may be a part of any other component of the air cleaner 128 as long as it is within the scope of the present invention. Furthermore, it has the lock part 222 corresponding to the open position of an upper end side, and the closed position of a lower end side. The holding portion 210 of the choke plate 202 is engaged with these lock portions 222. Further, the holding part 210 may have elasticity so as to be appropriately engaged with the lock part 222. This substantially prevents the choke plate 202 from shifting from the open or closed position due to vibration of the engine 100 or other components. The displacement of the choke plate 202 may hinder the operation of the engine 100. For example, if the choke plate 202 is shifted from the open position to the closed position, the air supply to the engine 100 may be interrupted and the engine 100 may be stopped halfway. It will also be apparent to those skilled in the art that the choke plate 202 is held in the open and closed positions by any other means such as one or more springs, electromagnetic systems, and the like.

  As shown in FIGS. 8A and 8B, the air cleaner body 134 has a first passage groove 224 and a second passage groove 226. The first passage groove 224 and the second passage groove 226 together form a part of the auxiliary passage 402. The first passage groove 224 communicates with the retention part 220 of the chamber 136. Further, the second passage groove 226 communicates with the mixture side opening 138. The first passage groove 224 and the second passage groove 226 are grooves formed integrally in the air cleaner body 134. In the closed position of the choke plate 202, the extension 212 of the choke plate 202 at least substantially seals the second passage groove 226, thereby preventing any fluid from flowing out through the mixture side opening 138. The extension 212 has a peripheral lining (not shown) for proper sealing. Further, in the closed position, the first passage groove 224 and the second passage groove 226 do not communicate with each other, and the fluid substantially flows out from the mixture side opening 138 through the first passage groove 224 and the second passage groove 226. To prevent. However, in the open position of the choke plate 202, the connecting groove 228 on the first surface 302 (FIG. 9A) of the choke plate 202 communicates the first passage groove 224 and the second passage groove 226 so that the blowback fuel stays in the retention portion 220. To the mixture side opening 138. The connecting portion groove 228 is an auxiliary passage forming portion provided on the first surface 302 of the choke plate 202 and forms a part of the auxiliary passage 402 (shown in FIGS. 9A and 9B).

  That is, the auxiliary passage 402 includes a first passage groove 224, a second passage groove 226, a connection groove 228, a first surface 302 that faces the first and second passage grooves 224 and 226, and an air cleaner that faces the connection groove 228. It is formed by the surface 135 of the main body 134 into a single continuous tube. Since the grooves 224, 226, and 228 are closed by the surfaces 135 and 302, only the both ends of the auxiliary passage 402 are open. Therefore, in the present embodiment, the portion of the first surface 302 of the choke plate 202 that covers the first and second passage grooves 224 and 226 also forms part of the auxiliary passage 402. is there.

  It will be apparent to those skilled in the art that the shapes and relative sizes of the first passage groove 224, the second passage groove 226, and the connection groove 228 are for illustrative purposes only. The first passage groove 224, the second passage groove 226, and the connection groove 228 may have any shape and relative size within the scope of the present invention. For example, the first passage groove 224 may have a linear shape instead of the curved shape shown in FIGS. 8A and 8B. Further, the first passage groove 224 may have an effective flow length shorter than that of the second passage groove 226.

  FIG. 9A shows a choke plate 202 having a first surface 302 according to a seventh embodiment of the present invention. As shown in FIG. 9A, the first surface 302 of the choke plate 202 has a connecting groove 228. Further, the choke plate 202 has an opening 304 through which the fastening member 216 passes.

  FIG. 9B is a cross-sectional view of the choke plate 202 along the axis A-A ′ in FIG. 9A. As shown in FIG. 9B, the connecting groove 228 is a concave groove on the first surface 302 of the choke plate 202. It will be apparent to those skilled in the art that the connecting groove 228 may have any cross section such as a semicircle or an open polygon within the scope of the present invention.

[Eighth Embodiment]
FIG. 10 shows an air cleaner 128 according to the eighth embodiment of the present invention. As shown in FIG. 10, the air cleaner body 134 has a single auxiliary passage 402 that connects the retention portion 220 and the mixture side opening 138. Further, the auxiliary passage 402 is formed by a passage groove 227 formed integrally with the surface 135 of the air cleaner main body 134 and a part of the first surface 302 (see FIG. 9A) of the choke plate 202 covering the passage groove 227. Alternatively, the auxiliary passage 402 may be a separate tube attached to the second surface 203 (see FIG. 9B) of the choke plate 202 by various means such as adhesives, mechanical fasteners, welding. Further, the auxiliary passage 402 may be any shape within the scope of the present invention.

[Ninth Embodiment]
FIG. 11A shows an air cleaner 128 according to a ninth embodiment of the present invention. As shown in FIG. 11A, the choke plate 202 has an auxiliary passage 502. The auxiliary passage 502 is located between the first surface 302 and the second surface 203 of the choke plate 202 and is provided through the thick portion (shown in detail in FIG. 11B). The auxiliary passage 502 connects the staying part 220 to the mixture side opening 138 at the open position of the choke plate 202. As shown in FIG. 11A, the auxiliary passage 502 has a linear shape. However, the auxiliary passage 502 may have any shape as long as it is within the scope of the present invention.

  FIG. 11B is a cross-sectional view of the air cleaner 128 along axis B-B ′ in FIG. 11A. As shown in detail view C of the choke plate 202, the auxiliary passage 502 is located between the first surface 302 and the second surface 203 of the choke plate 202 and in the vicinity of the second surface 203. Further, the auxiliary passage 502 has a tubular shape having a substantially elliptical cross section. However, the auxiliary passageway 502 may have any other cross section such as, but not limited to, a circle, an ellipse, a polygon. Further, the auxiliary passage 502 may be a groove provided in the first surface 302 of the choke plate 202 or may be a separate member attached to the second surface 203.

The present invention is not limited to each of the embodiments described above, but includes modifications within a range in which the object of the present invention can be achieved.
For example, the engine of each of the above embodiments is a stratified scavenging type, but the air supply device of the present invention may be applied to a conventional type two-stoke engine that is not stratified scavenging.

  The carburetor 15 in each of the above embodiments is integrally provided with the carburetor-side air passage 20, but such an air passage is formed by a pipe member or the like that is separate from the carburetor, and is arranged independently of the carburetor. May be. In such a case, a carburetor used for a conventional type two-stroke engine can be used.

  In each of the above embodiments, there is only one pipe 31 forming the auxiliary passage, but a plurality of auxiliary passages may be formed by using a plurality of pipes. In such a case, the proximal ends of the plurality of pipes are all communicated with the staying portion 29 of the air cleaner 16, but the distal ends are not necessarily communicated with the same portion, and the distal end of one pipe is connected to the crankcase chamber 6. Alternatively, the tip of another pipe may be connected to a different location such as to the cylinder chamber 8.

  In the fifth and sixth embodiments, the pipe 31 is disposed inside the air cleaner 16, but, for example, a pipe-shaped auxiliary passage is built in the inner surface of the case 23 of the air cleaner 16 by integral molding. The pipe 31 may be omitted.

  The air supply device of the present invention can be suitably used for, for example, a two-stroke engine used in a portable work machine such as a brush cutter or a chain saw.

DESCRIPTION OF SYMBOLS 1 Engine main body 2 Air supply device 5A Intake port 6 Crankcase chamber 8 Cylinder chamber 14 Insulator 15 Carburetor 16 Air cleaner 17 Insulator side air-fuel mixture passage 19 Carburetor side air-fuel mixture passage 25 Mixture-side opening 29 Retention part 31 Pipe 34 as an auxiliary passage Heat insulating material 39 Clearance 100 Two-stroke engine 102 Air supply device 104 Cylinder block 106 Crankcase 108 Cylinder 110 Cylinder chamber 112 Crankcase chamber 114 Crankshaft 116 Piston 118 Connecting rod 120 Intake port 122 Exhaust port 124 Exhaust muffler 126 Spark plug 128 Air cleaner 130 ... Carburetor 132 Insulator 134 Air cleaner body 135 Surface 136 Air cleaner Chamber 138 Mixture-side opening 140 Mixture-side opening 141 Prevention plate 142 Carburetor-side mixture passage 144 144 Carburet-side air passage 146 Insulator-side mixture passage 148 Insulator-side air passage 202 Choke plate 203 Second surface 204 First block portion 206 First 2 block part 208 actuating part 210 holding part 212 extending part 214 actuating lever 216 fastening member 218 guide part 220 staying part 222 lock part 224 first passage groove 226 second passage groove 227 passage groove 228 connection groove 302 first surface 304 opening Part 402 Auxiliary passage 502 Auxiliary passage

Claims (19)

An air supply device for a two-stroke engine,
The air supply device
An insulator attached to the engine body, having an insulator-side mixture passage communicating with an intake port provided in the engine body of the two-stroke engine;
A carburetor that has a carburetor-side air-fuel mixture passage communicating with the insulator-side air-fuel mixture passage, and is attached to the insulator;
An air cleaner attached to the carburetor, having an air-fuel mixture-side opening communicating with the carburetor-side air-fuel mixture passage;
Inside the air cleaner is provided with a retention portion for retaining blowback fuel returning from the mixture side opening,
An air supply apparatus comprising an auxiliary passage having a proximal end connected to the staying portion and a distal end connected to a portion of a crankcase chamber provided in the engine body where pressure fluctuations reach. The air supply device according to claim 1,
An air supply device, wherein a tip of the auxiliary passage is connected to the crankcase chamber itself. The air supply device according to claim 1,
The air supply device, wherein a tip of the auxiliary passage is connected to a cylinder chamber provided in the engine body. The air supply device according to claim 1,
The air supply device according to claim 1, wherein a tip end of the auxiliary passage is connected to a carburetor-side mixture passage of the carburetor. The air supply device according to claim 1,
The air supply device according to claim 1, wherein a tip of the auxiliary passage is connected to an insulator-side air-fuel mixture passage of the insulator. The air supply device according to claim 1,
The tip of the auxiliary passage is connected to a gap formed between opposing surfaces of the carburetor and the air cleaner,
The air supply device, wherein the gap communicates with the carburetor-side mixture passage. The air supply device according to claim 1,
The air supply device, wherein a tip of the auxiliary passage is connected to the mixture side opening. In the air supply device according to claim 6 or 7,
The air supply device, wherein the auxiliary passage is provided in the air cleaner. The air supply device according to claim 8, wherein
A choke plate provided to freely open and close the mixture side opening;
The choke plate is provided with an auxiliary passage forming portion that forms at least a part of the auxiliary passage when the choke plate is positioned in a state in which the mixture side opening is opened. A featured air supply device. The air supply device according to claim 9, wherein
The auxiliary passage is provided on the surface of the air cleaner body and has a first passage groove having one end communicating with the stay portion, and a second passage provided on the surface of the air cleaner body and one end communicating with the mixture side opening. Formed by a groove and the auxiliary passage forming portion,
The auxiliary passage forming portion is a connecting groove that communicates a part of the surface of the choke plate that faces and covers the first and second passage grooves and the other ends of the first and second passage grooves. There is an air supply device. The air supply device according to claim 10, wherein
The air supply device, wherein the second communication groove is closed by the choke plate when the choke plate is positioned in a state where the air-fuel mixture side opening is closed. The air supply device according to claim 9, wherein
The auxiliary passage is formed by a communication groove having one end communicating with the staying portion and the other end communicating with the mixture-side opening, and the auxiliary passage forming portion,
The air supply device according to claim 1, wherein the auxiliary passage forming portion is a part of a surface of the choke plate facing and covering the passage groove. The air supply device according to claim 9, wherein
The air supply device according to claim 1, wherein the auxiliary passage has a tubular shape that is provided so as to penetrate through a thick portion of the choke plate and communicates the staying portion with the mixture-side opening. The air supply device according to any one of claims 9 to 13,
The air cleaner body is provided with a pair of lock portions corresponding to the opening / closing positions of the mixture side opening by the chalk plate,
The choke plate is provided with a holding portion that engages with the lock portion. The air supply device according to claim 14, wherein
The pair of lock portions is provided on the end side of the curved rib along the opening / closing locus of the chalk plate,
The curved rib has an upper end side positioned in the vicinity of the mixture side opening, a lower end side positioned in the vicinity of the staying portion, and a guide portion that guides blowback fuel from the mixture side opening to the staying portion side. An air supply device characterized by that. The air supply device according to any one of claims 1 to 15,
The air supply device, wherein the auxiliary passage is formed by a pipe. The air supply device according to any one of claims 1 to 16,
An air supply device, wherein at least a part of the auxiliary passage is covered with a heat insulating material. The air supply device according to any one of claims 1 to 17,
The air supply device according to claim 1, wherein the staying portion is provided at a position where blowback fuel from the mixture side opening drops and stays. The air supply device according to any one of claims 1 to 18,
An air supply apparatus, wherein the air supply apparatus is applied to a piston valve type two-stroke engine in which the intake port is opened and closed by a piston.

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