JP2013170472A - Gas engine and gas engine work machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas engine having superior starting performance even if a gas cylinder is first set thereto at a low temperature or at the start of work, and to provide a work machine using the gas engine.SOLUTION: A gas engine 1 operating using, as fuel, a liquefied gas from a gas cylinder is configured so that a branch means (metering valve 30) for branching a fuel passage is provided in fuel passages 901, 902 which connect a regulator 7 to a socket 26 to which the gas cylinder 20 is attached and which constitute vaporizers for vaporizing liquid fuel, and the branch means communicates with the internal space of a crankcase 14 via a passage 36. During the start of the engine, the metering valve 30 is operated to directly introduce a constant amount of fuel into the crankcase 14 so as to improve the starting performance of the engine. Since the metering valve 30 is disposed near the gas cylinder 20, and during the start of the engine, the metering valve is positioned in the liquid fuel which is contained fully in the fuel passages 901, 902, the constant amount of liquid fuel can be supplied into the crankcase 4 when a cap 31 is depressed.

Description

  The present invention relates to a gas engine, and more particularly to a gas engine used in a brush cutter or the like using a cassette type gas cylinder filled with liquefied fuel, and a gas engine working machine using the same.

  For example, as shown in Patent Document 1, a gas engine using a cassette type gas cylinder filled with liquefied petroleum gas is known. Many cassette-type gas cylinders generally use liquefied butane. A conventional gas engine is shown in FIGS. In FIG. 5, the gas engine 200 sets the gas cylinder 20 horizontally so that the tip 24 of an L-shaped fuel take-out pipe 23 provided in the gas cylinder 20 is positioned in the vicinity of the lower end of the gas cylinder 20. In the gas cylinder 20 set in this way, the liquid fuel 22 is stored below, and the vaporized fuel 21 is stored at the saturated vapor pressure above. For this reason, the liquid fuel 22 is always supplied to the engine from the fuel take-out pipe 23. When the stem 25 at the tip of the gas cylinder 20 is inserted into the socket 26, it flows through the check valve 27, the passage 28, and the passage 29. The liquid fuel 22 is vaporized by the heat of the cylinder 3 or the like in the fuel passage 91 that also serves as the vaporizer 9 that is bent around the side surface of the cylinder 3, and a first decompression chamber and a second decompression chamber to be described later of the regulator 7 are provided. After passing and adjusting the pressure, the air is mixed with the air from the intake port 6 and supplied into the cylinder 3 through the crankcase 4 to be compressed and mixed to be ignited and exploded by the spark plug 2.

  6 is a longitudinal sectional view of the regulator of FIG. As shown in FIG. 6, generally in the first decompression chamber 71 of the regulator 7, the first lever 72, the first diaphragm 73, and the first spring 74 are about 350 mmAq (gauge pressure), about 0 when expressed in ISO units. In the second decompression chamber 75, the second lever 76, the needle valve 79, the second diaphragm 77, and the second spring 78 are approximately 0 mmAq (gauge pressure), and approximately 0 MPa (in ISO units). The pressure is adjusted to (gauge pressure) (= atmospheric pressure). When the pressure in the first decompression chamber 71 becomes higher than about 0.0035 MPa (gauge pressure), the first diaphragm 73 is pushed down against the 74 biasing force of the first spring. Then, the first diaphragm 73 connection side 723 of the first lever 72 is lowered, and the valve portion 721 on the other end side is swung around the fulcrum 722 to close the passage 81. Conversely, when the pressure in the first decompression chamber 71 becomes lower than about 0.0035 MPa (gauge pressure), the first diaphragm 73 is pushed up by the urging force of the first spring 74, and the first lever 72 is moved in the opposite direction. The valve portion 721 opens around the fulcrum 722 and opens the passage 81 to flow in. When a predetermined pressure is reached, the valve portion 721 closes the passage and maintains a constant pressure.

  The second decompression chamber 75 is operated in the same manner. When the piston (not shown) rises, the crankcase 4 chamber side below the piston becomes negative pressure, and the piston (not shown) further serves as an air supply port (not shown) of the cylinder 3. As a result, the pressure in the second decompression chamber 75 communicating with the intake passage 85 becomes lower than about 0 MPa (gauge pressure). Then, since the left surface of the second diaphragm 77 is open to the atmospheric pressure, it is pushed rightward (FIG. 7) by the differential pressure between the left and right surfaces of the second diaphragm 77. Since one end side (upper end side in FIG. 7) 763 of the second lever 76 is in contact with the second diaphragm 77, the upper end side 763 of the second lever 76 resists the urging force of the second spring 78. And the lower end side 761 of the second lever 76 moves leftward. A needle valve 79 is attached to the lower end side 761 of the second lever 76, and the needle valve 79 moves leftward. Then, the passage 82 and the needle valve 79 are gradually opened, and the first decompression chamber 71 and the second decompression chamber 75 communicate with each other through the passage 82. Since the pressure in the first decompression chamber 71 is about 0.0035 MPa (gauge pressure) and the second decompression chamber 75 is a negative pressure, it flows from the first decompression chamber 71 side to the second decompression chamber 75 side, As a result, the air passes through the main jet 83 and mixes with air from the intake port 6 where it flows into the crankcase 4 and the cylinder 3. This operation continues while the gas engine 200 is activated. When the gas engine 200 is stopped, that is, when a piston (not shown) is stopped, the crankcase 4 under the piston (not shown) does not become negative pressure, so suction to the crankcase 4 side is eliminated. Then, the second decompression chamber 75 communicated from the intake passage 85 becomes atmospheric pressure, and the second diaphragm 77 returns to the original position (moves leftward in FIG. 7). The second lever 76 also swings so that the upper end side 763 of the second lever 76 moves leftward by the urging force of the second spring 78, and the lower end side 761 of the second lever 76 moves rightward. Accordingly, the needle valve 79 also moves to the right, returns to the original position, closes the passage 82, and keeps the pressure in the second decompression chamber 75 constant (about 0 MPa (gauge pressure)). At this time, the flow stops completely.

  Further, in a gas engine using liquefied petroleum gas shown in Patent Document 2, fuel is sucked and supplied directly into the crankcase by a negative pressure in the crankcase through a pressure regulator and a metering device. This is because, in the same way as gasoline, the means for mixing into the intake air through a carburetor or the like prevents wasteful release from the intake port to the atmosphere when it is supplied to the intake port side where air is sucked.

JP-A-7-34980 Japanese Patent Laid-Open No. 5-86986

  By the way, in the gas engine of patent document 1, since the cylinder and the vaporizer part of the vicinity of the cylinder are cold at the time of starting in a low temperature environment around 5 ° C., the vaporization of the liquid fuel supplied from the gas cylinder becomes insufficient. There is a problem that startability deteriorates.

  Further, particularly at the start immediately after setting the gas cylinder for the first time at the beginning of the work with this type of working machine, as shown in FIGS. 5 to 8, the liquid fuel 22 is extruded at a stretch by the saturated vapor pressure of the fuel in the gas cylinder 20, Since the cross-sectional area and volume of the fuel passage 91 in the vaporizer 9 are very small and the temperature of the vaporizer 9 is low, the liquid fuel 22 flows through the passage in the vaporizer 9. Therefore, as shown in FIG. 8, the air 95 in the initial fuel passage 91 before setting the gas cylinder 20 is pushed out to the regulator 7 side by the liquid fuel 22. Then, as shown in FIG. 7, when the valve portion 721 of the first lever 72 of the regulator 7 becomes about 0.0035 MPa (gauge pressure) or more, the passage 81 is closed, so that the valve portion 721 of the first lever 72 is immediately closed. The air 95 in the original vaporizer 9 remains confined while being compressed between the portion 721 and the liquid level 220 of the liquid fuel 221 flowing in from the gas cylinder 20 side. Fuel gas evaporated from the liquid surface is mixed in the confined compressed air 95 and becomes the same pressure as the saturated vapor pressure of the liquid fuel at this temperature. Since the remaining air 95 that has been trapped is compressed first, the amount of fuel gas is very small. The first decompression chamber 71 of the regulator 7 is further confined with air with a lean fuel gas. The second decompression chamber 75 has only air and no fuel gas.

  Even if the starter 40 is pulled and the crankshaft is rotated in order to start the gas engine 200 in this state, the amount of fuel gas sucked into the crankcase 4 side through the regulator 7 is scarcely initially. Cannot start without ignition and explosion. Many crankshafts are turned, that is, the starter 40 is pulled, and the air that is initially trapped in the regulator 7 and the vaporizer 9 is sucked and extracted, and the fuel gas must be sucked into the regulator 7, which is a work with fatigue. There was a problem. Further, the saturated vapor pressure around 5 ° C. of liquefied butane, which is a general fuel, is about 0.02 MPa (gauge pressure), and the extrusion pressure from the gas cylinder is low, so the liquid fuel in the fuel passage 91 of the vaporizer 9 is low. There is a problem that the position (height) of the liquid surface 220 reaches a short position, and the portion where the fuel is present becomes far from the regulator 7, so that the fuel supply becomes insufficient and the startability is deteriorated.

  Further, in the gas engine of Patent Document 2, fuel is directly supplied into the crankcase, but the principle of the pressure regulator is the same as described above. Therefore, at the start immediately after the gas cylinder is set for the first time at the start of work, The trapped air remains in the passage between the pressure devices, and there is the same problem as described above.

  The present invention has been made in view of the above background, and its object is to provide a gas engine using a cassette type gas cylinder filled with liquefied fuel that has good startability even when the gas cylinder is set for the first time at a low temperature or at the beginning of work. And providing a gas engine working machine.

  According to one aspect of the present invention, a two-cycle engine body in which a piston reciprocates in a cylinder fixed to a crankcase and a cassette-type gas cylinder filled with liquefied gas burned in the cylinder are mounted. A socket for taking out the liquefied gas, a regulator that regulates the gas from the gas cylinder and mixes it with the air sucked from the intake port, and a fuel passage that connects the socket and the regulator so as to pass near the cylinder. In the gas engine having the vaporizer portion that heats and vaporizes the liquefied gas by arranging, a metering valve for branching the fuel passage is provided, and a passage for branching from the metering valve to the crankcase and communicating therewith is provided. The metering valve is elastically energized by a valve shaft having a groove of a constant volume, and is normally in communication with the fuel passage of the vaporizer section and normally closed by the groove when the valve shaft is pressed, It has a second opening that is opened by the groove only when the valve shaft is closed and pressed, and communicates with the first opening and the regulator by the vaporizer, and the second opening and the crankcase are communicated by the passage. Ru

  According to another feature of the present invention, the gas engine is configured such that the metering valve is provided in the vaporizer near the side surface of the crankcase. Moreover, it was set as the gas engine working machine which drives working machines, such as a brush cutter, using this gas engine.

  According to the first aspect of the present invention, it is possible to supply the liquefied gas (liquid fuel) directly into the crankcase by the metering valve even at the start immediately after the gas cylinder is set for the first time at the beginning of work at a low temperature. Since the crankcase is initially at atmospheric pressure and has a large volume, the liquefied gas is reliably vaporized. Since the vaporized fuel enters the cylinder from the crankcase, it becomes easy to ignite and explode, and the startability of the gas engine can be improved. Once started, the air initially trapped in the vaporizer and regulator is immediately sucked out by the continuous rotation of the crankshaft and filled with fuel, so normal operation continues. In addition, the vaporizer also warms and promotes fuel vaporization.

  According to the second aspect of the present invention, since the metering valve is configured by using the valve shaft having a groove with a constant volume, if a valve shaft is pushed in, a certain amount of liquefied gas is always supplied into the crankcase. Can be improved.

  According to the invention of claim 3, since the metering valve is provided in the vaporizer near the side surface of the crankcase, the metering valve is reliably filled with the liquefied gas even immediately after the gas cylinder is set for the first time at the beginning of the operation at low temperature. Vaporized fuel can be reliably supplied to the crankcase side.

  According to the invention of claim 4, since the gas engine working machine that drives the work equipment using the gas engine of claim 1 or 2 is used, a cassette cylinder that has good startability and is easy to use even in a low temperature environment is used. An engine working machine can be provided.

  The above and other objects and novel features of the present invention will become apparent from the following description and drawings.

1 is a perspective view showing an overall configuration of a brush cutter equipped with a gas engine according to an embodiment of the present invention. It is the rear view of the gas engine which concerns on this invention, and is the figure which showed the part with sectional drawing. It is a fragmentary sectional view of the principal part which shows the flow of the gas in the vaporizer 9 of FIG. It is a partial expanded sectional view which shows operation | movement of the metering valve 30 of FIG. It is the gas engine rear view which concerns on a prior art example, and is the figure which showed the one part with sectional drawing. It is a longitudinal cross-sectional view of the regulator 7 of FIG. It is a fragmentary sectional view of the principal part which shows the flow of the gas in the vaporizer 9 of FIG. It is a fragmentary sectional view of the principal part which shows the state in the vaporizer 9 before the gas cylinder attachment in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. As shown in FIG. 1, a brush cutter 1001 equipped with a two-cycle gas engine using liquefied petroleum gas (LPG) or the like filled in a cassette gas cylinder as a fuel has a rotary blade 1003 attached to the tip of an operating rod 1002. The gas engine 1 is attached to the rear end of the operation rod 1002. The output of the gas engine 1 is supplied to the rotary blade 1003 through a drive shaft that is inserted into the operation rod 1002. The operator operates the brush cutter 1001 by holding the handle 1004 attached to the operation rod 1002. The cassette type gas cylinder containing the fuel of the gas engine is a container standardized by, for example, JIS standard S2148 “Fuel container for cassette stove” and is attached to the gas cylinder case 1005.

  As shown in FIG. 2, the gas engine 1 has a cylinder 3 with an ignition plug 2 attached to the upper part (upper part of the figure) and a crankcase 4 attached to the lower part of the cylinder 3 (lower part of the figure). A two-cycle engine body in which a piston (not shown) reciprocates inside the cylinder 3, a muffler 5 attached to an exhaust port (not shown) of the cylinder 3, and an intake port (not shown) side of the cylinder 3 Connected to the regulator 7, the gas inlet case 6 attached to the lower part of the crankcase 4 (downward in the drawing), the gas cylinder 20 in the gas cylinder case 10, and the gas cylinder case 10. A vaporizer 9 serving as a fuel passage and a metering valve 30 connected to the vaporizer 9 near the side surface of the crankcase 4 are configured.The metering valve 30 serves as a branching means for branching the fuel passage. By interposing the metering valve 30, the vaporizer 9 is divided into a lower vaporizer 901 on the lower side and an upper vaporizer 902 on the upper side across the metering valve 30.

  As shown in FIG. 4 (a), the metering valve 30 has a cylindrical valve body 32 having a first opening 321 penetrating vertically on one end side and connected to a lower vaporizer 901 and an upper vaporizer 902. A valve shaft 33 that is urged by a spring 34 and is slidable in the axial direction of the valve body 32 is inserted into the inner periphery of the valve 32. The valve shaft 33 is provided with a groove portion 331 that is a concave portion having a constant diameter and a smaller diameter than an outer shape that becomes a guide diameter when sliding in the valve body 32. The groove portion 331 is always provided in the fuel passage 91 of the vaporizer 9 via the first opening 321 of the valve body 32, and the left and right sides thereof are sealed with seals, and the lower vaporizer 901, the groove portion 331, and the upper portion are sealed. The vaporizer 902 is in communication. The valve shaft 33 is movable in the axial direction by a fixed stroke until the cap 31 attached to the left end of the valve shaft 33 is pushed and stops against the valve body 32. A second opening 322 of the valve body 32 is provided at a position separated from the first opening 321 of the valve body 32 to the right in the axial direction by a predetermined stroke. A passage 36 is connected to the second opening 322, and a check valve 37 is connected to the second opening 322. A passage communicating with the crankcase 4 is provided.

  According to the gas engine 1 configured as described above, before setting the gas cylinder 20 for the first time, the passages 28 and 29 of the socket 26, the lower vaporizer 901, the groove portion 331 in the metering valve 30, and the upper vaporizer 902 are set as in FIG. The first decompression chamber 71 and the second decompression chamber 75 of the regulator 7 are filled with air 95. At the start in a low temperature environment around 5 ° C., immediately after the gas cylinder 20 is set for the first time at the beginning of the work, the vaporizer 9 is also cooled and has a small passage cross-sectional area. Therefore, as shown in FIG. 3, the liquid in the gas cylinder 20 The fuel 22 is extruded at a time with the saturated vapor pressure (about 0.02 MPa (gauge pressure) at that time, and the lower vaporizer 901 and the groove portion 331 in the metering valve 30 pass through the passages 28 and 29 while pushing in the air 95 that was before setting. 6 flows into the upper vaporizer 902. Then, since the regulator 7 is the same regulator as the conventional one shown in Fig. 6, the valve portion 721 of the first lever 72 of the regulator 7 closes the passage 81 when the pressure is about 0.0035 MPa (gauge pressure) or more. Therefore, the liquid fuel that has been closed immediately and has flowed in from the valve portion 721 of the first lever 72 and the gas cylinder 20 side. 3, the air 95 in the original vaporizer 9 remains confined while being compressed between the liquid surface 220 and the liquid surface 220, and the confined compressed air 95 contains fuel evaporated from the liquid surface. A small amount of gas is mixed to the same pressure as the saturated vapor pressure of the liquid fuel at this temperature, and the amount of fuel gas is very small because the remaining trapped air 95 is compressed first. Air in which the fuel gas is further diluted is confined in the first decompression chamber 71. Only the air is contained in the second decompression chamber 75. There is no fuel gas in the low pressure environment around 5 ° C. The fuel in the gas cylinder at this time 3, the liquid level 220 reaches the position above the upper vaporizer 902. The groove in the metering valve 30 is also filled with liquid fuel.

  When starting the gas engine 1 in this state after setting the gas cylinder 20 as described above, the cap 31 of the metering valve 30 is pushed in the direction of the arrow against the urging force of the spring 34 as shown in FIG. And a certain amount of liquid fuel is confined in the part partitioned off by the groove part 331 and the valve body 32 inner periphery. As shown in FIG. 4C, when the fixed stroke is pushed, the cap 31 hits the valve body 32 and stops. At this time, the groove 331 of the valve shaft 33 is aligned with the second opening 322 of the valve body 32 and communicates with the passage 36. The passage 36 and the check valve 37 communicate with the crankcase 4 below the piston (not shown) and are at atmospheric pressure. Since the volume of the crankcase 4 below the piston (not shown) is about 40 cc in this type of small engine, the liquid fuel confined in the groove 331 is converted into the passage 36 and the check valve by vapor pressure. While extruding the air in the part 37 into the crankcase 4, it is surely vaporized and flows into the crankcase 4 to become an air-fuel mixture. The amount of the vaporized fuel is set to an amount that is greater than the amount of vaporized fuel supplied from an intake port (not shown) during normal continuous operation, and is fuel rich. Since the fuel is butane or the like, even if the fuel is excessively concentrated, it is surely vaporized here, and there is no problem because the electrode of the spark plug does not get wet and does not cause ignition failure like gasoline.

  When the cap 31 hits the valve body 32 and stops pushing after being stopped, the cap 31 and the valve shaft 33 move to the left by the biasing force of the spring 34 and return to their original positions. The first opening 321 of the valve body 32 of the metering valve 30 communicates with the lower vaporizer 901 and the upper vaporizer 902, and the second opening 322 returns to the closed state (FIG. 4A).

  Thereafter, when the starter 40 is pulled, the piston (not shown) moves up and down by the rotation of the crankshaft, and the air-fuel mixture in the crankcase 4 below the piston (not shown) passes through the scavenging port (not shown). It is supplied into a cylinder 3 above a piston (not shown), and after ignition, is ignited and explodes by a spark plug 2 to start the engine. Even when the piston (not shown) descends and the air-fuel mixture in the crankcase 4 below the piston (not shown) is compressed, the check valve 37 closes the passage 36, so that the air-fuel mixture is wasted. There is no escape. Then, after starting the gas engine 1, the air 95 trapped in the second decompression chamber 75, the first decompression chamber 71, and the upper vaporizer 902 in the regulator 7 is sucked out in a very early stage due to the continuous rotation of the engine. It is gone and becomes a fuel component. Further, since the upper vaporizer 902 is warmed by the heat of the cylinder 3, it is possible to sufficiently vaporize the liquid fuel in the portion from the upper vaporizer 902 to the first decompression chamber 71 of the regulator 7 and the entire vaporizer 9.

  Further, when the temperature becomes lower than around 5 ° C., the saturated vapor pressure in the gas cylinder 20 becomes further lower, so that the height 220 of the liquid fuel 221 in the upper vaporizer 902 immediately after setting the gas cylinder 20 for the first time becomes lower. However, since the position of the metering valve 30 is set in the vicinity of the side of the crankcase 4 that is as low as possible in the span of the vaporizer 9, the liquid fuel 221 reaches the metering valve 30 sufficiently to fill the groove 331 and vaporize in the crankcase 4. It becomes possible to supply fuel.

  According to the gas engine 1 described above, the metering valve 30 is provided in the vaporizer 9 in the vicinity of the side surface of the crankcase 4, and the metering valve 30 is pushed in so that a certain amount of liquid fuel is always supplied into the crankcase 4. Therefore, even at the start immediately after the gas cylinder 20 is set for the first time at the beginning of the work at a low temperature, the fuel is reliably supplied into the crankcase 4 and vaporized, and then supplied to the cylinder 3 to improve the engine startability. I can plan.

  As mentioned above, although this invention was demonstrated based on the Example, this invention is not limited to the above-mentioned Example, A various change is possible within the range which does not deviate from the meaning. For example, the gas engine and the gas engine working machine according to the present invention can be applied to an engine used for a chain saw, a hedge trimmer, and the like in addition to the brush cutter 1001. Further, the passage 36 from the metering valve 30 does not necessarily communicate with the crankcase 4, and the passage 36 may communicate with the intake passage on the intake port side. In addition, if the vaporizer can promote vaporization in the middle of the fuel passage of the regulator from the socket, heat exchange is performed via a heat transfer plate provided in the cylinder, or heat such as exhaust gas that is a heat source other than the cylinder is used. You may do it.

DESCRIPTION OF SYMBOLS 1 Gas engine 3 Cylinder 4 Crankcase 6 Inlet part 7 Regulator 9 Vaporizer 10 Gas cylinder case 20 Gas cylinder 22 Liquid fuel 26 Socket 30 Metering valve 31 Cap 32 Valve body 33 Valve shaft 36 Passage 37 Check valve 40 Starter 71 First decompression chamber 72 First lever 75 Second decompression chamber 91 Fuel passage 95 Air 200 Gas engine 220 Liquid surface 221 Liquid fuel 331 Groove 721 Valve 901 Lower vaporizer 902 Upper vaporizer 1001 Brush cutter 1002 Operating rod 1003 Rotary blade 1004 Handle 1005 Gas cylinder case

Claims (5)

A two-cycle engine main body in which a piston reciprocates in a cylinder fixed to a crankcase;
A socket for taking out the liquefied gas by mounting a cassette type gas cylinder filled with the liquefied gas burned in the cylinder;
A regulator that regulates the gas from the gas cylinder and mixes it with the air sucked from the air inlet;
In a gas engine having a vaporizer section that connects the socket and the regulator and heats and vaporizes the liquefied gas,
A metering valve for branching the fuel passage is provided,
A gas engine having a passage branched from the metering valve to the crankcase and communicating therewith. The metering valve is elastically biased by a valve shaft having a groove with a constant volume,
A first opening that normally communicates with the fuel passage of the vaporizer and is closed by the groove only when the valve shaft is pressed, and is normally closed and opened by the groove only when the valve shaft is pressed. A second opening to be
2. The gas engine according to claim 1, wherein the vaporizer unit communicates with the first opening and the regulator, and the second opening and the crankcase communicate with each other through the passage.   The gas engine according to claim 1 or 2, wherein the vaporizer unit heats the liquefied gas by being disposed so as to pass in the vicinity of the cylinder.   The gas engine according to claim 2 or 3, wherein the metering valve is provided in the vaporizer near the side surface of the crankcase. The gas engine working machine which drives a working equipment using the gas engine as described in any one of Claim 1 to 4.

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