JP6401651B2 - Power working machine - Google Patents

Description

  The present invention relates to a power working machine such as a chain saw, an engine cutter, a hedge trimmer, a brush cutter, etc., in which an internal combustion engine is mounted as a power source for driving a working unit, and is particularly provided in an intake system of the internal combustion engine. The present invention relates to a portable power working machine that reduces as much as possible a temperature rise after an internal combustion engine of a carburetor is stopped.

  An example of a chain saw (top handle chain saw) which is one of this type of portable power working machine is shown in FIG. A conventional saw 1 'shown in the figure has a small air-cooled gasoline engine (hereinafter referred to as an internal combustion engine) mounted as a power source for driving a working unit mounted in a cylinder horizontally, and an air cleaner and a throttle valve are installed in the intake system of the internal combustion engine. A chain saw body equipped with a heat insulator (also referred to as an intake pipe or a vent pipe) with an intake passage connecting the intake passage of the carburetor and the intake port communicating with the cylinder of the internal combustion engine. 10 '. A saw chain set (not shown) including a guide bar and a saw chain (chain with a cutter) that is slidably slidable around the guide bar is attached to the front side of the chain saw body 10 '. .

  A hand guard 2 'also serving as a brake lever is disposed on the front upper side of the chain saw body 10', and a top handle 4 'provided with a throttle trigger 5' is disposed on the upper side of the chain saw body 10 '. A substantially U-shaped front handle 3 ′ is disposed from the front portion of the top handle 4 ′ to the rear lower portion of the chain saw body 10 ′.

  In the chain saw 1 'as described above, air cleaned (filtered) by an air cleaner is mixed with fuel by a carburetor to generate an air-fuel mixture, and the air-fuel mixture is sucked into a cylinder of an internal combustion engine and is then injected by an ignition plug. By igniting and burning, the piston inserted in the cylinder is reciprocated, the crankshaft connected to the piston is rotated, and the saw chain as the working unit is driven.

  For the internal configuration of the above-described conventional chain saw 1 ', see, for example, Patent Documents 1 and 2 and the like.

  By the way, in the carburetor provided in the intake system of the internal combustion engine, during operation of the internal combustion engine, a relatively low temperature air-fuel mixture flows through a suction passage provided therein and cooling air is generated around the air. Since it flows, the temperature rise is suppressed, in other words, the temperature is kept substantially constant. However, when the internal combustion engine is stopped, the air-fuel mixture does not flow through the suction passage and the cooling air does not flow, and the carburetor is heated by the radiant heat from the internal combustion engine, so that the temperature of the carburetor may increase. Are known. In general, in a portable power working machine such as the above-described top handle chain saw, the carburetor is disposed above the internal combustion engine (see Patent Documents 1 and 2), and the rising heat from the internal combustion engine (updraft) Since the vaporizer is also heated by the heat contained in the vaporizer, the temperature of the vaporizer further increases. And when the temperature of the vaporizer rises and exceeds the boiling point temperature of gasoline used as fuel, the fuel boils in the vaporizer, and unless the temperature of the vaporizer falls below the boiling point temperature, It becomes difficult to restart the internal combustion engine (referred to as a vapor lock phenomenon or percolation).

  Particularly in recent portable power machines, the amount of heat generated from the internal combustion engine increases with the demand for higher output, and the carburetor and the internal combustion engine come closer to each other with the demand for smaller size and lighter weight. Therefore, the temperature rise of the carburetor after the stop of the internal combustion engine tends to increase.

  As a conventional technique for coping with radiant heat from such an internal combustion engine, Patent Document 3 discloses that an air cleaner is fixed at a position close to the upper part of the internal combustion engine (internal combustion engine), and the air cleaner has an outer wall surface facing the internal combustion engine. The thing which equipped with the heat-shielding board which provides a rib and covers this rib is disclosed.

  In the prior art described in Patent Document 3, the air cleaner is prevented from being heated by radiant heat from the internal combustion engine by means of a heat shield attached to a portion facing the internal combustion engine on the outer wall surface of the air cleaner. By suppressing the rise in the temperature of the intake air passing through the cylinder and preventing the output of the internal combustion engine from decreasing, a rib is formed on the outer wall surface of the air cleaner, and a heat shield is attached to the rib. The vibration of the hot plate is effectively prevented, and the radiated sound from the air cleaner is reduced.

JP 2007-185894 A JP 2011-132931 A JP 2002-276485 A

  However, in a recent portable power working machine in which the carburetor and the internal combustion engine are arranged close to each other, a rib or a heat shield as described in Patent Document 3 is provided on the outer wall surface of the carburetor. It is extremely difficult to provide. Further, in the carburetor provided in the intake system of the internal combustion engine, as described in Patent Document 3, even if a heat shield plate for blocking radiant heat from the internal combustion engine is provided, the effect of suppressing the temperature rise is obtained. It has been confirmed by experiments by the present inventors that it cannot be obtained.

  The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a carburetor disposed in an intake system of an internal combustion engine at a low cost without affecting the appearance (outside dimensions). An object of the present invention is to provide a power working machine that can effectively reduce the temperature rise after the internal combustion engine stops and can improve the restartability of the internal combustion engine.

  The inventors of the present invention have made a simple configuration by effectively using the space around the intake pipe having the intake passage connecting the intake passage of the carburetor and the intake port of the internal combustion engine as a result of earnest research by demonstration experiments and the like. Thus, it has been found that the above problems can be solved.

  That is, the power working machine according to the present invention is equipped with an internal combustion engine as a power source for driving the working unit, a carburetor is provided in the intake system of the internal combustion engine, and a suction passage provided inside the carburetor. A power working machine in which an intake pipe having an intake passage connecting to an intake port communicating with a cylinder of the internal combustion engine is mounted, and the suction passage of the carburetor is formed toward the internal combustion engine side. The mounting plate on which the carburetor is placed and fixed is provided with an opening into which the suction pipe is fitted, and is a surface on the side opposite to the carburetor mounting surface of the mounting plate and on the internal combustion engine side A plurality of ribs arranged at intervals are disposed around the opening on the back surface of the vaporizer mounted.

  In a preferred aspect, the plurality of ribs are formed integrally with the mounting plate.

  In another preferred aspect, the mounting plate is provided with a peripheral wall that forms the opening and extends from the vaporizer mounting rear surface of the mounting plate toward the internal combustion engine, and the plurality of ribs are formed on the peripheral wall. It is arranged around.

  In another preferred aspect, each of the plurality of ribs is disposed in parallel with a cylinder axis of the internal combustion engine.

  In another preferred embodiment, a notch is provided in a part of the rib.

  In a further preferred aspect, a part of the mounting plate is bent so as to surround a space around the passage member.

  According to the power working machine of the present invention, the mounting plate on which the carburetor is placed and fixed is provided with the opening into which the intake pipe having the intake passage connecting the intake passage of the carburetor and the intake port of the internal combustion engine is fitted. In addition, a plurality of ribs arranged at intervals are arranged around the opening on the carburetor mounting rear surface of the mounting plate on the internal combustion engine side of the mounting plate, and the carburetor suction is performed during the operation of the internal combustion engine. Since a relatively low-temperature air-fuel mixture flows through the passage, a space defined between adjacent ribs among the plurality of ribs arranged around the opening passes through a vaporizer and a suction pipe. An air layer having a temperature equivalent to the temperature of the relatively low temperature air-fuel mixture is formed. Under such circumstances, when the internal combustion engine is stopped, the air-fuel mixture does not pass through the carburetor or the suction pipe, but a relatively low-temperature air layer is maintained in the space between the adjacent ribs. It becomes a state. After the internal combustion engine is stopped, heat (radiant heat or rising heat) released from the internal combustion engine is transferred to the carburetor through the mounting plate, and the temperature of the carburetor rises. Part of the heat from the engine is absorbed by an air layer (a layer having a larger specific heat than the mounting plate) that stays in the space between the ribs provided around the opening in the mounting plate. Therefore, the amount of heat absorbed by the mounting plate is reduced, the temperature rise of the mounting plate is reduced, and the temperature rise of the vaporizer itself is also reduced. As a result, the temperature rise of the carburetor disposed in the intake system of the internal combustion engine after the stop of the internal combustion engine can be effectively reduced at a low cost without affecting the external appearance (outside dimensions), and the internal combustion engine can be reused. The startability, particularly the restartability in a high temperature state can be improved. Further, since the restartability is improved in this way, the number of times of start (recoil) is reduced, fatigue due to recoiling can be reduced, and durability and safety can be improved.

The principal part expanded sectional view which shows the principal part of one Embodiment of the chain saw which is one of the power working machines which concern on this invention. The principal part expansion perspective view which shows the vaporizer mounting surface side of the attachment plate of the chain saw shown by FIG. The principal part expansion perspective view which shows the vaporizer mounting back surface side (around opening) of the attachment plate of the chain saw shown in FIG. The principal part expansion perspective view which shows the deformation | transformation form on the vaporizer mounting back surface side (around opening) of the attachment plate of the chain saw shown in FIG. The whole perspective view which shows an example of the chain saw which is one of the portable power working machines.

  Embodiments of a power working machine according to the present invention will be described below with reference to the drawings.

  FIG. 1 is an enlarged cross-sectional view showing a main part of an embodiment of a chain saw that is one of the power working machines according to the present invention, and FIGS. 2 and 3 are chain saw mounting plates shown in FIG. It is a principal part expansion perspective view which shows the vaporizer mounting surface side of this, and a vaporizer mounting back surface side (around opening). In addition, below, only the internal combustion engine and the carburetor surrounding, which are the main parts of the chain saw 1 of the present embodiment, will be specifically described. For the detailed structure other than the main part of the chain saw 1 of this embodiment, refer to the chain saw 1 'shown in FIG. However, the chain saw 1 of the present embodiment described below has a different engine type from the chain saw described in Patent Document 1 (the chain saw described in Patent Document 1 is equipped with a layered scavenging engine). Note that the arrangement relationship between the handle and the intake system is different from that of the chain saw described in the above (the chain saw described in Patent Document 2 is not a top handle type, but the handle is connected to the rear of the intake system).

  The chain saw body 10 of the chain saw 1 of the illustrated embodiment basically includes a carburetor 13 that mixes air cleaned (filtered) with an air cleaner 12 and fuel to generate an air-fuel mixture; An internal combustion engine 11 as a power source that burns the air-fuel mixture and drives the working unit (saw chain), and the carburetor 13 and the internal combustion engine 11. And a suction pipe (also referred to as a bellows) 15 made of an elastic material for forming an intake passage 15a to be introduced into the cylinder 11b.

  In the top handle type chain saw 1 of the present embodiment, a heat radiation space including a carburetor 13 is disposed between a top handle 4 provided on an upper portion of a chain saw body 10 and a cylinder 11 b of the internal combustion engine 11. Specifically, the internal combustion engine 11 described above is mounted horizontally in a storage chamber 22 defined by a partition wall 21 on the lower side of the chain saw body 10, and an intake port 11a is opened above the cylinder 11b. Yes. The carburetor 13 is placed and fixed on a mounting plate 23 that is spaced above the partition wall 21 so that a suction passage 13a provided in the carburetor 13 faces the intake port 11a. The intake pipe 15 has a cylindrical shape in which a tapered intake passage 15a having a slightly reduced diameter toward the internal combustion engine 11 is formed. The suction pipe 15 has an upper end portion (an end portion on the carburetor 13 side) in contact with a lower end portion of the carburetor 13, and a lower end portion (an end portion on the internal combustion engine 11 side) in the cylinder 11 b of the internal combustion engine 11. Abutting on the communicating intake port 11a, the upstream opening of the intake passage 15a communicates with the suction passage 13a of the carburetor 13, and the downstream opening of the intake passage 15a communicates with the intake port 11a. It is arranged in a space G between the partition wall 21 on the engine 11 side and the mounting plate 23 on which the carburetor 13 is placed.

  In the present embodiment, the mounting plate 23 on which the vaporizer 13 is placed and fixed is formed with an opening 25a into which the upper end portion of the suction pipe 15 is fitted, and the mounting plate 23 has a vaporizer mounting back surface (vaporization). A peripheral wall 25 that is externally fitted to the suction pipe 15 is integrally provided so as to extend toward the internal combustion engine 11 side from a surface opposite to the carburetor mounting surface on which the evaporator 13 is placed. The inner peripheral surface of the peripheral wall 25 is formed with a step so as to abut and lock the hook-shaped portion 15 b provided at the upper end portion of the suction pipe 15. Further, the periphery of the opening 25a on the carburetor mounting back surface of the mounting plate 23 on the internal combustion engine 11 side, that is, the periphery of the peripheral wall 25, is connected to the peripheral wall 25 as can be understood with reference to FIG. A plurality of ribs 24 arranged at predetermined intervals are integrally provided. Here, each rib 24 made of a flat plate member made of synthetic resin is disposed substantially parallel to the cylinder axis of the internal combustion engine 11, and each rib 24 provided on the upper portion around the peripheral wall 25 is It extends to a curved portion 23a of a mounting plate 23 to be described later.

  Further, in the present embodiment, the top handle 4 side (upper side) portion of the mounting plate 23 is bent toward the internal combustion engine 11 side so as to surround the space G around the suction pipe 15 (bent portion 23a). ). The bent portion 23a is integrated with a connecting portion in which a lower portion of the top handle 4 is connected to an air cleaner container (portion for storing the air cleaner 12), and a user's hand holding the top handle 4 by the bent portion 23a. Is prevented from coming into contact with each component arranged in the space G around the suction pipe 15, and the air in the space G that has absorbed heat generated from the internal combustion engine 11 flows toward the top handle 4 side. It has been suppressed to continue.

  In the chain saw (powered work machine) 1 configured as described above, external air is introduced into the air cleaner 12 during work (while the internal combustion engine 11 is in operation), and the air cleaned (filtered) by the air cleaner 12 is vaporized. The air-fuel mixture is mixed with fuel in the suction device 13 (the intake passage 13a), and the air-fuel mixture is generated. It is sucked into the cylinder 11b. At this time, the carburetor 13 disposed above the internal combustion engine 11 is exposed to heat (radiant heat or rising heat) released from the internal combustion engine 11, but the suction passage 13 a of the carburetor 13 has a relatively low temperature. Since the air-fuel mixture flows and cooling air flows around it, the temperature rise can be suppressed. At this time, the peripheral wall 25 of the mounting plate 23 fitted around the suction pipe 15 that connects the suction passage 13a of the carburetor 13 and the intake port 11a of the internal combustion engine 11 is disposed around the peripheral wall 25. In the slit-shaped space S defined by the adjacent ribs 24 among the plurality of ribs 24, there is an air layer having a temperature equivalent to the temperature of the relatively low temperature air-fuel mixture passing through the vaporizer 13 and the suction pipe 15. Thus, the heat from the internal combustion engine 11 is also blocked, and the carburetor 13 is suppressed from being heated by the heat from the internal combustion engine 11.

  Under such circumstances, when the internal combustion engine 11 is stopped, the air-fuel mixture does not pass through the carburetor 13 and the suction pipe 15 and the cooling air does not flow. However, in the space S between the adjacent ribs 24 described above. Is maintained in a state where a relatively low temperature air layer is maintained.

  After the internal combustion engine 11 is stopped, the heat released from the internal combustion engine 11 is transferred to the mounting plate 23 via the partition wall 21 and the space G between the partition wall 21 and the mounting plate 23, and further to the vaporizer 13. Although the temperature of the carburetor 13 rises as a result of heat transfer, in this embodiment, a part of the heat from the internal combustion engine 11 described above is provided between the ribs 24 provided around the peripheral wall 25 of the mounting plate 23. Is absorbed by an air layer (a layer having a larger specific heat than the mounting plate 23) staying in the space S. Therefore, the amount of heat absorbed (reached) by the mounting plate 23 is reduced, the temperature rise of the mounting plate 23 is reduced, and the temperature rise of the vaporizer 13 itself is also reduced. Thereby, the temperature increase after the internal combustion engine 11 of the carburetor 13 provided in the intake system of the internal combustion engine 11 is stopped can be effectively reduced at a low cost without affecting the appearance (outside dimension), and the internal combustion The restartability of the engine 11, especially the restartability in a high temperature state can be improved. Further, since the restartability is improved in this way, the number of times of start (recoil) is reduced, fatigue due to recoiling can be reduced, and durability and safety can be improved.

Note that the dimensional shape of each rib 24, the installation range of the rib 24, and the like depend on the power performance of the internal combustion engine 11, the dimensional shape of the carburetor 13 and the suction pipe 15, and the like. The installation area of the rib 24 (installation area on the back of the vaporizer mounted on the mounting plate 23) is 200 mm ² or more, and the total volume of the air layer (space S) formed between the ribs 24 is 1500 mm ³ or more. It has been proved by a demonstration experiment by the present inventors that it is preferable.

  Moreover, in this embodiment, since each rib 24 provided around the peripheral wall 25 in the mounting plate 23 is formed integrally with the mounting plate 23 and the peripheral wall 25, an increase in the number of parts is suppressed and the manufacturing cost is reduced. The surge can be suppressed.

  Further, in the present embodiment, each rib 24 is arranged in parallel with the cylinder axis of the internal combustion engine 11, that is, along the front-rear direction in the illustrated example, so that each rib 24 can be set relatively large, and the vaporizer It is possible to more effectively reduce the temperature rise after the 13 internal combustion engines 11 are stopped.

  In the above-described embodiment, each rib 24 is formed integrally with the mounting plate 23 and the peripheral wall 25, but it is needless to say that each rib 24 may be formed separately from the mounting plate 23 and the peripheral wall 25. is there. Further, the peripheral wall 25 and the mounting plate 23 may be formed separately.

  In the above-described embodiment, each rib 24 is disposed substantially parallel to the cylinder axis of the internal combustion engine 11, but each rib 24 may be disposed perpendicular to the cylinder axis of the internal combustion engine 11. For example, you may arrange | position in the grid | lattice form, the radial shape etc. which extend toward the outer side from the surrounding wall 25, etc. In the above-described embodiment, the ribs 24 are arranged at substantially equal intervals, but it goes without saying that the intervals between the adjacent ribs 24 may be non-uniform. In the above-described embodiment, eight ribs 24 having a thickness of about 1.5 mm are arranged side by side with an equal interval of 1.5 mm between the ribs 24. The interval between 24 (that is, the width of the space S), the number of ribs 24 formed around the peripheral wall 25, and the like are not limited to the illustrated example, and can be appropriately changed as long as the above-described effects can be exhibited.

  Furthermore, in the above-described embodiment, the rib 24 made of a flat plate member is formed around the peripheral wall 25 on the vaporizer mounting back surface side of the mounting plate 23, but the increase in weight is suppressed or the stress due to thermal deformation of each rib 24 In order to alleviate the concentration, as shown in FIG. 4, an intermittent surface having a notch 26 in a part of each rib 24 may be used. In the modification shown in FIG. 4, as a result of the plurality of notches 26 being formed in each rib 24, a plurality of columnar shapes arranged around the peripheral wall 25 of the mounting plate 23 with a predetermined interval in appearance. The member is projected.

  In the above-described embodiment, the present invention has been described with respect to a chain saw as a portable power working machine, particularly a top handle type chain saw having a top handle provided on the top thereof. Needless to say, the present invention can be applied to engine cutters (cut-off saws), hedge trimmers, blowers, brush cutters and the like in addition to chain saws. Needless to say, as the internal combustion engine mounted as a power source, for example, all internal combustion engines including a stratified scavenging engine as described in Patent Document 1 can be applied.

1 Chain saw (power work machine)
DESCRIPTION OF SYMBOLS 10 Chain saw body 11 Internal combustion engine 11a Intake port 11b Cylinder 12 Air cleaner 13 Vaporizer 13a Suction passage 15 Suction pipe 15a Intake passage 15b Ridge part 21 Bulkhead 22 Storage chamber 23 Mounting plate 23a Bending part 24 Rib 25 Perimeter wall 25a Opening

Claims (8)

An internal combustion engine is mounted as a power source for driving the working unit, a carburetor is provided in an intake system of the internal combustion engine, and an intake port provided in the carburetor and an intake port communicating with the cylinder of the internal combustion engine A power working machine in which an intake pipe having an intake passage is connected to the carburetor and the suction passage of the carburetor is formed toward the internal combustion engine,
The mounting plate on which the carburetor is placed and fixed is provided with an opening into which the suction pipe is fitted, and is a surface opposite to the carburetor mounting surface of the mounting plate and is a carburetor on the internal combustion engine side A power working machine, wherein a plurality of ribs arranged at intervals are disposed around the opening on the mounting back surface.   The power working machine according to claim 1, wherein the plurality of ribs are formed integrally with the mounting plate.   The power working machine according to claim 2, wherein the plurality of ribs are made of resin.   The mounting plate is provided with a peripheral wall that forms the opening and extends from the vaporizer mounting back surface of the mounting plate toward the internal combustion engine, and the plurality of ribs are disposed around the peripheral wall. The power working machine according to any one of claims 1 to 3, wherein the power working machine is provided.   5. The power working machine according to claim 1, wherein each of the plurality of ribs is disposed in parallel with a cylinder axis of the internal combustion engine.   The power working machine according to any one of claims 1 to 5, wherein a part of the rib is provided with a notch.   The power work machine according to any one of claims 1 to 6, wherein a part of the mounting plate is bent so as to surround a space around the suction pipe.   The power work according to claim 7, wherein the power work machine is a top handle type chain saw in which a heat radiation space including the carburetor is disposed between the cylinder and the handle of the internal combustion engine. Machine.

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