Patent Description:
This disclosure relates to a starting-fuel supply device configured to automatically supply a starting fuel to a carburetor at the time of start of an engine to enable smooth start of the engine. Further, this disclosure also relates to an adapter configured to form the starting-fuel supply device and to an engine work machine including the starting-fuel supply device.

In <CIT>, there is described a starting-fuel supply device configured to automatically supply a starting fuel to a carburetor, which is configured to supply an air-fuel mixture containing a fuel and air to an engine, at the time of start of an engine to enable smooth start of the engine. The starting-fuel supply device couples a fuel chamber of the carburetor including a fuel pump and an intake passage to each other through a starting-fuel supply passage. A starting-fuel supply valve to be electrically opened and closed is provided in the starting-fuel supply passage. The starting-fuel supply valve is actuated based on an output signal of a primary coil of a flywheel magneto so as to start the engine by a recoil operation. Further, the starting-fuel supply device includes a manual pump, which is configured to charge a fuel in the fuel tank to the fuel chamber before the start of the engine, in a passage that connects the fuel chamber and a fuel tank to each other.

In the starting-fuel supply device, the fuel in the fuel tank is circulated through the fuel pump, the fuel chamber, the manual pump, and the fuel tank in the stated order by an operation of the manual pump before the start of the engine. When a worker performs the recoil operation so as to start the engine, the fuel in the fuel chamber is sucked into the intake passage owing to the Venturi effect in the intake passage. At the same time, the starting-fuel supply valve is automatically opened so that the fuel in the fuel chamber is sucked into the intake passage through the starting-fuel supply passage owing to the Venturi effect in the intake passage.

In the starting-fuel supply device, however, the starting-fuel supply valve may stick to a valve seat to make the actuation of the starting-fuel supply valve unreliable in some cases. In particular, when a stop period of a two-stroke internal combustion engine using a blended fuel of gasoline and oil becomes longer, an oil concentration of the blended fuel increases due to volatilization of gasoline while the engine is being stored. Thus, the oil may be present in a gap between the starting-fuel supply valve and the valve seat to adhere to both of the starting-fuel supply valve and the valve seat, and the sticking of the starting-fuel supply valve is liable to occur.

<CIT> and <CIT> disclose starting fuel supply devices.

The object of the present invention is an engine work machine according to claim <NUM>.

This disclosure has been made in view of the circumstances described above, and has an object to provide a starting-fuel supply device, with which sticking of a starting-fuel supply valve can be prevented.

This disclosure has another object to provide an adapter configured to form the starting-fuel supply device.

Further, this disclosure has another object to provide an engine work machine including the starting-fuel supply device.

In order to solve the above-mentioned problem, according to one embodiment of this disclosure, there is provided a starting-fuel supply device, including: a starting-fuel supply valve configured to automatically add a starting fuel to an air-fuel mixture generated by a carburetor; and a valve chamber for the starting-fuel supply valve, wherein a fuel in a fuel tank is configured to move a fuel in the fuel tank to the carburetor through the valve chamber for the starting-fuel supply valve with use of a manual pump configured to suck up the fuel in the fuel tank into the carburetor before start of an engine, and wherein the valve chamber is disposed at a position below an intake passage of the carburetor when the engine is in a stored state.

According to one embodiment of this disclosure, by an operation of the manual pump before the start of the engine, the fuel tank is configured to move the fuel in the fuel tank to the carburetor through the valve chamber for the starting-fuel supply valve. The fuel, which has been moved into the valve chamber, comes into contact with the starting-fuel supply valve to lubricate the starting-fuel supply valve. As a result, the sticking of the starting-fuel supply valve is prevented before the start of the engine. Thus, the starting-fuel supply valve is reliably actuated at the time of start of the engine to improve startability of the engine. Further, the valve chamber for the starting-fuel supply valve is disposed at a position below the intake passage of the carburetor when the engine is in a stored state, and hence the fuel does not drop by its own weight. Thus, the fuel is less liable to leak from the valve chamber while the engine is being stored. Accordingly, the sticking of the starting-fuel supply valve is easily prevented. Further, the fuel is less liable to leak from the valve chamber while the engine is being stored, and the fuel is accumulated in the valve chamber before the fuel moves into the carburetor. Thus, the operation of the manual pump is less required at the time of next start of the engine. Accordingly, high operability at the start of the engine is attained.

According to one embodiment of this disclosure, the engine is a stratified scavenging engine, an internal space of a suction pipe disposed between a cylinder block and the carburetor is divided into an air passage and an air-fuel mixture passage, and the starting fuel is supplied to at least one of air passage and the air-fuel mixture passage.

In the above-mentioned embodiment, when the air-fuel mixture passage of the suction pipe is arranged on a lower side, specifically, below the air passage in the suction pipe, the starting fuel is less liable to flow into the air passage. Thus, characteristics of the stratified scavenging engine are not impaired. Further, when the air passage of the suction pipe is arranged on the lower side, specifically, below the air passage in the suction pipe, the starting fuel is supplied to the air passage. However, the starting fuel is used at the time of start of the engine, and thus even when the starting fuel flows into the air passage, less contributes to deterioration of exhaust gas components.

According to one embodiment of this disclosure, the starting-fuel supply valve is provided to an adapter and the valve chamber is formed in the adapter, the adapter being formed separately from the carburetor, the adapter is configured to be disposed between a suction pipe configured to connect the carburetor to a cylinder block and the carburetor, and the adapter has a starting-fuel discharge passage, which brings the valve chamber and the intake passage of the carburetor into communication with each other when the starting-fuel supply valve is actuated to be opened.

According to the above-mentioned embodiment, when the adapter is disposed between an existing carburetor, which does not include the starting-fuel supply valve and the valve chamber, and the suction pipe, a starting-fuel supply function can be attained with direct use of the existing carburetor. Further, with the formation of the starting-fuel discharge passage in the adapter, the starting-fuel discharge passage can be shortened. Thus, the starting fuel can be fed with high responsiveness.

According to one embodiment of this disclosure, the suction pipe is formed of a bellows. According to the above-mentioned embodiment, when the adapter is disposed between the existing carburetor, which does not include the starting-fuel supply valve and the valve chamber, and the suction pipe, a dimension of the adapter can be absorbed owing to contractility of the suction pipe. Thus, increase in size of configurations from the carburetor to the cylinder block can be prevented.

According to one embodiment of this disclosure, the suction pipe and the adapter are integrally molded. In this case, the suction pipe and the adapter are integrally molded, and hence workability in assembly is improved.

According to one embodiment of this disclosure, there is provided an adapter configured to form the starting-fuel supply device, the adapter including an annular mounting portion configured to be disposed between the suction pipe and the carburetor, the annular mounting portion is formed integrally with a portion having valve mounting portions configured to mount the starting-fuel supply valve and the valve chamber, and a starting-fuel discharge port communicating with the starting-fuel discharge passage is formed in an inner peripheral surface of the annular mounting portion.

With the adapter according to one embodiment of this disclosure, the adapter can be disposed between the existing carburetor and the suction pipe with use of the annular mounting portion. The starting-fuel supply function can easily be attained with direct use of the existing carburetor and the suction pipe. Thus, the adapter according to the embodiment of this disclosure is convenient. Specifically, the adapter has versatility.

According to one embodiment of this disclosure, an engine work machine includes one of the starting-fuel supply devices and the adapter. With the engine work machine according to one embodiment of this disclosure, the same actions and effects as those described above are attained.

In the following, embodiments of this disclosure are described with reference to the accompanying drawings.

A starting-fuel supply device according to one embodiment of this disclosure forms a part of an intake system of an engine to be mounted mainly in a portable engine work machine. The starting-fuel supply device is used in combination with a carburetor configured to supply an air-fuel mixture to the engine. Examples of the engine work machine using the starting-fuel supply device according to this disclosure include a work machine including a small air-cooled two-stroke internal combustion engine mounted therein as a power source, such as a chain saw, a grass trimmer, a power cutter, a hedge trimmer, and a power blower.

As illustrated in <FIG>, a carburetor <NUM> is connected to a cylinder block <NUM> for forming an engine through a suction pipe <NUM> having a heat insulating property. An air purified in an air cleaner (not shown) is mixed with a fuel in the carburetor <NUM> to generate an air-fuel mixture. The air-fuel mixture is sucked into the cylinder block <NUM> through the suction pipe <NUM> and an intake port <NUM>. The generation of the air-fuel mixture in the carburetor <NUM> and the suction of the air-fuel mixture into the cylinder block <NUM> are achieved by an operation of a piston <NUM> that reciprocally slides inside the cylinder block <NUM>.

A type of the carburetor <NUM> to be used in combination with a starting-fuel supply device <NUM> according to this disclosure is not limited. However, as a carburetor suitable for a portable engine work machine in which a posture of a machine body is frequently changed during work, a diaphragm type carburetor having a well-known configuration itself is preferred. As illustrated in <FIG>, the carburetor <NUM> includes a fuel pump <NUM>, a fuel chamber <NUM>, and a main fuel discharge port <NUM>. The fuel pump <NUM> is connected to a fuel tank <NUM> of the engine work machine via a check valve. The fuel chamber <NUM> is connected to the fuel pump <NUM> via a check valve. The main fuel discharge port <NUM> is connected to the fuel chamber <NUM> via a check valve. The main fuel discharge port <NUM> is open to an intake passage <NUM> of the carburetor <NUM>.

The fuel pump <NUM> is preferably a pulse-control diaphragm pump to be driven by a pressure pulse generated in a crankcase <NUM> of an engine <NUM>. The fuel pump <NUM> sucks up the fuel from the fuel tank <NUM> to supply the fuel to the fuel chamber <NUM>. The fuel in the fuel chamber <NUM> is sucked through the main fuel discharge port <NUM> into the intake passage <NUM> due to a pressure decrease in the intake passage <NUM>, which is caused by a venturi <NUM>. When a worker operates an output operation member (not shown) of the engine work machine, an opening degree of a throttle valve <NUM> in the intake passage <NUM> is adjusted. As a result, an engine output in accordance with the opening degree of the throttle valve <NUM> is obtained.

A manual pump <NUM> is also disposed in the carburetor <NUM>. The manual pump <NUM> is configured to suck up the fuel in the fuel tank <NUM> into the fuel chamber <NUM> before start of the engine <NUM>. The manual pump <NUM> is disposed in a return flow passage <NUM> extending from the fuel chamber <NUM> to the fuel tank <NUM>. When the worker operates the manual pump <NUM> before the start of the engine <NUM>, the fuel in the fuel tank <NUM> is supplied to the fuel chamber <NUM> to fill the fuel chamber <NUM> with the fuel. At the same time, a surplus fuel and a gas such as air bubbles in the fuel chamber <NUM> are forced into the fuel tank <NUM>. The manual pump <NUM> may be provided integrally with the carburetor <NUM>, or may be provided separately from the carburetor <NUM>.

The starting-fuel supply device <NUM> according to this embodiment includes a starting-fuel supply valve <NUM> and a valve chamber <NUM>. The starting-fuel supply valve <NUM> is configured to automatically add a starting fuel to the air-fuel mixture generated in the carburetor <NUM> or an air having passed through the carburetor <NUM>. The valve chamber <NUM> accommodates a valve body <NUM> of the starting-fuel supply valve <NUM>. The fuel in the fuel tank <NUM> can be moved to the carburetor <NUM> through the valve chamber <NUM> by the operation of the manual pump <NUM>.

As illustrated in <FIG>, in this embodiment, the valve chamber <NUM> is disposed in the middle of a suction flow passage <NUM> extending from the fuel tank <NUM> to the fuel pump <NUM> of the carburetor <NUM>. Thus, when the fuel pump <NUM> is actuated, the fuel in the fuel tank <NUM> is moved into the fuel chamber <NUM> of the carburetor <NUM> through the valve chamber <NUM>. Further, in this embodiment, the valve chamber <NUM> is disposed at a position below the intake passage <NUM> of the carburetor <NUM> when the engine work machine including the engine <NUM> is in a stored state. Each of a fuel inlet <NUM> and a fuel outlet <NUM> communicates with the valve chamber <NUM>. The fuel inlet <NUM> communicates with the fuel tank <NUM> through a suction pipe <NUM>, and the fuel outlet <NUM> communicates with the fuel pump <NUM> via the check valve. A suction-side end portion 24a of the suction pipe <NUM> is positioned in a lower part of an internal space of the fuel tank <NUM>. A filter <NUM> configured to prevent suction of dust is provided to the suction-side end portion 24a.

An orifice (valve seat or flow passage hole) <NUM> is open to the valve chamber <NUM>. The orifice <NUM> communicates with an air-fuel mixture passage <NUM> of the suction pipe <NUM> via a starting-fuel discharge passage <NUM> and a starting-fuel discharge port <NUM>. When an air passage <NUM> of the suction pipe <NUM> is located on a lower side, specifically, below the air-fuel mixture passage <NUM>, the orifice <NUM> may communicate with the air passage <NUM>. The orifice <NUM> is always closed with the valve body <NUM> of the starting-fuel supply valve <NUM> except at the time of start of the engine. The starting-fuel supply valve <NUM> is actuated to be opened only at the time of start of the engine. As a result, the orifice <NUM> is opened. The starting-fuel discharge port <NUM> is open to the intake passage <NUM> on a downstream side with respect to the venturi <NUM>.

The starting-fuel supply valve <NUM> can be electrically controlled. For example, a solenoid valve (electromagnetic valve) is used as the starting-fuel supply valve <NUM>. As a power supply <NUM> for the starting-fuel supply valve <NUM>, for example, a battery to be mounted in the engine work machine can be used.

Further, the actuation of the starting-fuel supply valve <NUM> can be controlled, as described in <CIT>, based on an output signal of a primary coil of a flywheel magneto which is rotated by operating a recoil starter <NUM> configured to start the engine <NUM>. More specifically, when the worker operates the recoil starter <NUM>, an electromagnetic coil 18b of the starting-fuel supply valve <NUM> is excited by a control circuit <NUM> based on the output signal of the primary coil of the flywheel magneto. As a result, the starting-fuel supply valve <NUM> is actuated to be opened. Then, when the engine <NUM> starts idling, the electromagnetic coil 18b of the starting-fuel supply valve <NUM> is demagnetized by the control circuit <NUM> based on the output signal of the primary coil of the flywheel magneto. As a result, the starting-fuel supply valve <NUM> is closed.

With the configuration described above, when the engine <NUM> is to be started, the worker first operates the manual pump <NUM> to supply the fuel in the fuel tank <NUM> to the fuel chamber <NUM>. In this manner, the fuel in the fuel tank <NUM> is moved into the fuel pump <NUM> and the fuel chamber <NUM> through the valve chamber <NUM>. As a result, the fuel chamber <NUM> is filled with the fuel. At the same time, a surplus fuel and a gas such as air bubbles in the fuel chamber <NUM> pass through the return flow passage <NUM> to be forced into the fuel tank <NUM>. As a result, the engine <NUM> can be smoothly and reliably started.

Subsequently, after the worker turns on a start switch for the engine <NUM> and performs a pulling operation of the recoil starter <NUM>, the piston <NUM> is reciprocated inside the cylinder block <NUM> through intermediation of a crankshaft <NUM> and a connecting rod <NUM>. In synchronization with the reciprocation of the piston <NUM>, ignition is performed by an ignition device <NUM>. As a result of the reciprocation of the piston <NUM> inside the cylinder block <NUM>, a negative pressure is generated in the intake passage <NUM> of the carburetor <NUM>, and the fuel in the fuel chamber <NUM> is sucked into the intake passage <NUM> through the main fuel discharge port <NUM>. As a result, the air-fuel mixture is generated. Simultaneously with the pulling operation of the recoil starter <NUM> performed by the worker, the starting-fuel supply valve <NUM> is actuated to be opened. Thus, the orifice <NUM> is opened, and the fuel in the valve chamber <NUM> passes through the starting-fuel discharge passage <NUM> to be discharged into the air-fuel mixture passage <NUM> of the suction pipe <NUM> due to the negative pressure in the intake passage <NUM>. When the air passage <NUM> of the suction pipe <NUM> is arranged on the lower side, specifically, below the air-fuel mixture passage <NUM> in the suction pipe <NUM>, the fuel may be discharged to the air passage <NUM>. As a result, the starting fuel is supplied to the air-fuel mixture or the air to thereby smoothly start the engine <NUM>. When the engine <NUM> starts idling, the starting-fuel supply valve <NUM> is automatically closed by the control circuit <NUM>.

In this embodiment, before the start of the engine <NUM>, the fuel in the fuel tank <NUM> is moved into the fuel chamber <NUM> of the carburetor <NUM> through the valve chamber <NUM> by the operation of the manual pump <NUM>. The fuel, which has been moved into the valve chamber <NUM>, comes into contact with the valve body <NUM> of the starting-fuel supply valve <NUM> to lubricate the valve body <NUM>. As a result, the sticking of the valve body <NUM> to the orifice <NUM> can be prevented before the start of the engine <NUM>. Thus, the starting-fuel supply valve <NUM> is reliably actuated at the time of start of the engine <NUM>, and the startability of the engine <NUM> is improved. Further, the valve chamber <NUM> for the starting-fuel supply valve <NUM> is disposed at the position below the intake passage <NUM> of the carburetor <NUM> when the engine <NUM> (engine work machine) is in a stored state. Thus, the starting-fuel supply device has such a configuration that the fuel does not drop by its own weight, and the fuel is less liable to leak from the valve chamber <NUM> while the engine is being stored. Accordingly, the sticking of the valve body <NUM> is easily prevented. Further, the fuel is less liable to leak from the valve chamber <NUM> while the engine is being stored, and the fuel is accumulated in the valve chamber before the fuel moves into the carburetor. Thus, the operation of the manual pump <NUM> is less required at the time of next start of the engine <NUM>. Accordingly, high operability at the start of the engine is attained.

As a preferred embodiment, the engine <NUM> is a stratified scavenging engine. As indicated by imaginary lines in <FIG>, an internal space of the suction pipe <NUM> disposed between the cylinder block <NUM> and the carburetor <NUM> is suitably divided by a partition <NUM> into the air passage <NUM> on the upper side and the air-fuel mixture passage <NUM> on the lower side so that the starting fuel is supplied to the air-fuel mixture passage <NUM>. With the configuration described above, the starting fuel is less liable to move into the air passage <NUM>. Thus, characteristics of the stratified scavenging engine are not impaired. Further, when the air passage <NUM> of the suction pipe <NUM> is arranged on the lower side, specifically, below the air-fuel mixture passage <NUM>, the starting fuel is supplied to the air passage <NUM>. However, the starting fuel is used at the time of start of the engine, and thus less contributes to deterioration of exhaust gas components.

Further, as a preferred embodiment, as illustrated in <FIG>, there may also be adopted a configuration in which the starting-fuel supply valve <NUM> is provided to an adapter <NUM> and the valve chamber <NUM> is formed in the adapter <NUM>. In this configuration, the adapter <NUM> is formed separately from the carburetor <NUM>. In this case, the adapter <NUM> may be disposed between the suction pipe <NUM> configured to connect the carburetor <NUM> to the cylinder block <NUM> and the carburetor <NUM>. The adapter <NUM> has the starting-fuel discharge passage <NUM> configured to bring the valve chamber <NUM> and the intake passage <NUM> (the air-fuel mixture passage <NUM> and the air passage <NUM>) of the suction pipe <NUM> into communication with each other at the time of actuation of the starting-fuel supply valve <NUM> to open the starting-fuel supply valve <NUM>. Further, as described above, in the case of the stratified scavenging engine, when the partition <NUM> is provided to the adapter, the partition <NUM> divides the intake passage <NUM> inside the adapter. Thus, the characteristics of the stratified scavenging engine are further improved.

As illustrated in <FIG> and <FIG>, the adapter <NUM> is disposed between the carburetor <NUM> and the suction pipe <NUM>. The adapter of <FIG> is substantially the same as the adapter of <FIG>. The adapter of <FIG> is schematically illustrated so that orientations of the starting-fuel supply valve <NUM> and the valve chamber <NUM> are changed by <NUM> degrees from those of <FIG> for easy understanding of the flow passage of the fuel.

As illustrated in <FIG>, the adapter <NUM> includes an annular mounting portion <NUM>, which can be disposed between the carburetor <NUM> and the suction pipe <NUM>. Under a state in which the adapter <NUM> is disposed between the carburetor <NUM> and the suction pipe <NUM>, an inner peripheral surface 38a of the annular mounting portion <NUM> is smoothly connected to an inner peripheral surface 12a of the intake passage <NUM> of the carburetor <NUM> and an inner peripheral surface 3a of the suction pipe <NUM> (see <FIG>). The starting-fuel discharge port <NUM> is formed in the inner peripheral surface 38a of the annular mounting portion <NUM>. Valve mounting portions <NUM>, which are configured to mount the starting-fuel supply valve <NUM>, and the valve chamber <NUM> (see <FIG>) are formed integrally with the annular mounting portion <NUM>.

The adapter of <FIG> has a pair of protruding portions <NUM>, <NUM>. The pair of protruding portions <NUM>, which protrude radially outward, are formed at positions on the annular mounting portion <NUM>, which are opposed to each other. A through hole <NUM> passing in an axial direction of the annular mounting portion <NUM> is formed in each of the protruding portions <NUM>. The through holes <NUM>, <NUM> respectively match with a pair of bolt insertion holes <NUM>, <NUM> formed in the carburetor <NUM>. Bolts <NUM> inserted into the bolt insertion holes <NUM> of the carburetor <NUM> respectively pass through the through holes <NUM> of the protruding portions <NUM> to be screwed into screw holes <NUM> of the suction pipe <NUM> to thereby couple the carburetor <NUM>, the adapter <NUM>, and the suction pipe <NUM>.

As illustrated in <FIG> and <FIG>, an extending portion <NUM> is formed so as to extend downward from a lower part of the annular mounting portion <NUM>. At a lower end of the extending portion <NUM>, a pair of protruding portions <NUM>, <NUM> extending in directions opposite to each other are formed. The protruding portions <NUM>, <NUM> serve as valve mounting portions. A through hole <NUM> for mounting the valve is formed in each of the protruding portions <NUM> (see <FIG>). The pair of protruding portions <NUM>, <NUM> respectively match with a pair of mounting portions <NUM>, <NUM> formed on a valve case 18a for the starting-fuel supply valve <NUM>. A through hole <NUM> is also formed in each of the mounting portions <NUM> formed on the valve case 18a. After the pair of protruding portions <NUM> and the pair of mounting portions <NUM> are placed so as to match with each other, bolts (not shown) are inserted through the through holes <NUM> and <NUM>, which match with each other, to be fastened with nuts. As a result, the starting-fuel supply valve <NUM> is fixed to the adapter <NUM>.

As illustrated in <FIG>, the valve chamber <NUM> having a recessed shape is formed between the pair of protruding portions <NUM>, <NUM> serving as the valve mounting portions. As illustrated in <FIG>, the orifice <NUM> is located at a position in the valve chamber <NUM>, which is on the side opposite to an open side of the valve chamber <NUM>. Then, as illustrated in <FIG>, when the starting-fuel supply valve <NUM> is mounted to the adapter <NUM>, the orifice <NUM> is closed with the valve body <NUM> of the starting-fuel supply valve <NUM> so that the valve chamber <NUM> has a closed space. As illustrated in <FIG> and <FIG>, the orifice <NUM> communicates with the starting-fuel discharge port <NUM> via the starting-fuel discharge passage <NUM> formed in the extending portion <NUM>. Thus, when the starting-fuel supply valve <NUM> is actuated to be opened, the valve chamber <NUM> comes into communication with the starting-fuel discharge port <NUM>.

As illustrated in <FIG>, the fuel inlet <NUM> and the fuel outlet <NUM>, each having a protruding-pipe shape, are formed at the lower end of the extending portion <NUM>. The fuel inlet <NUM> and the fuel outlet <NUM> both communicate with the valve chamber <NUM>, as illustrated in <FIG>. As already described above, the fuel inlet <NUM> communicates with the fuel tank <NUM> through the suction pipe <NUM> (see <FIG>), and the fuel outlet <NUM> communicates with the fuel pump <NUM> via the check valve.

With the configuration described above, when the adapter <NUM> is disposed between the existing carburetor <NUM>, which does not include the starting-fuel supply valve <NUM> and the valve chamber <NUM>, and the suction pipe <NUM>, a starting-fuel supply function can be attained with direct use of the existing carburetor <NUM>. Further, with the formation of the starting-fuel discharge passage <NUM> in the adapter <NUM>, the starting-fuel discharge passage <NUM> can be shortened. Thus, the starting fuel can be fed with high responsiveness.

The suction pipe <NUM> is suitably formed of a contractile bellows as a preferred embodiment although the suction pipe <NUM> is not limited thereto. With use of the bellows for the suction pipe <NUM>, when the annular mounting portion <NUM> of the adapter <NUM> is disposed between the existing carburetor <NUM>, which does not include the starting-fuel supply valve <NUM> and the valve chamber <NUM>, and the suction pipe <NUM>, a thickness dimension of the annular mounting portion <NUM> can be absorbed owing to contractility of the suction pipe <NUM>. Thus, increase in size of the configurations from the carburetor <NUM> to the cylinder block <NUM> can be prevented.

Further, as another preferred embodiment, the suction pipe <NUM> and the adapter <NUM> may also be integrally molded. In this manner, workability in assembly of the engine <NUM> is also improved. The suction pipe <NUM> and the adapter <NUM> can be integrally molded by, for example, injection molding of a resin, which is noncontractile unlike the bellows.

Claim 1:
An engine work machine, comprising:
an engine (<NUM>) having a cylinder block (<NUM>) as a power source;
a carburetor (<NUM>);
a suction pipe (<NUM>) disposed between the cylinder block (<NUM>) and the carburetor (<NUM>);
a fuel tank (<NUM>);
a manual pump (<NUM>) configured to suck up fuel in the fuel tank (<NUM>) into the carburetor (<NUM>) before start of the engine (<NUM>);
an adapter (<NUM>) formed separately from the carburetor (<NUM>) and disposed between the carburetor (<NUM>) and the suction pipe (<NUM>); and
a starting-fuel supply device (<NUM>),
wherein
the starting-fuel supply device (<NUM>) includes
a starting-fuel supply valve (<NUM>) configured to automatically add a starting fuel to an air-fuel mixture generated by the carburetor (<NUM>); and
a valve chamber (<NUM>) in the starting-fuel supply valve (<NUM>), the valve chamber (<NUM>) being upstream of a fuel chamber (<NUM>) of the carburetor (<NUM>) such that the starting fuel in the fuel tank (<NUM>) is movable, by the manual pump (<NUM>), into the fuel chamber (<NUM>) via the valve chamber (<NUM>), and
the valve chamber (<NUM>) is disposed at a position below, in a gravity direction toward a lower part of an internal space of the fuel tank (<NUM>) when the engine (<NUM>) is in a stored state, at least one of
an intake passage (<NUM>) of the carburetor (<NUM>),
an intake passage (<NUM>) of the suction pipe (<NUM>), or
an intake passage (<NUM>) of the adapter (<NUM>).