JP2004293542A - Dual fuel engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dual fuel engine which prevents problems that blow-by of gaseous fuel occasionally occurs at the start of the gaseous fuel, electric power of an electric actuator becomes necessary during gaseous fuel operation, and the link mechanism of a choke valve is complicated. <P>SOLUTION: When the gaseous fuel is selected for a fuel selection means 1 at the time of energization to the starter 9 of a dual fuel engine, a startup gas valve 38 is opened by being energized by a valve drive circuit 39. Then the startup gaseous fuel is supplied from a gas supply source 31 to a fuel mixer 2 through the primary room 33 of a vaporizer 32 and a startup gas pathway 37. The start of the gaseous fuel is made possible even when the gas cutout function of a pressure locking mechanism (36) is actuated. When a starter switch 7 is OFF, the startup gas valve 38 is closed by stopping energization of the startup gas valve 38 by the valve drive circuit 39, and the choke valve 3 is kept fully open by an energization means 4. The start of the gaseous fuel is not affected even when the gas cutout function of the pressure locking mechanism 36 is actuated. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

    The present invention relates to a dual fuel engine.

  Conventionally, as a dual fuel engine, as shown in FIG. 5, similarly to the present invention, a liquid fuel and a gas fuel are selected by fuel selection means (51), and the selected fuel is supplied to a fuel mixer (52) common to both fuels. There is one that supplies the fuel and mixes the fuel and air with a fuel mixer (52) (see Patent Document 1).

  This type of engine is mounted, for example, on a machine such as a man lift or a forklift in which a person performs a lifting operation while riding on a wagon. When a machine equipped with this engine is used, exhaust gas can be purified by using gas fuel in indoor work, and output can be secured by using liquid fuel in outdoor work. .

However, this conventional engine is different from the present invention and is as follows.
The choke valve (53) of the fuel mixer (52) is urged by the urging spring (54) to the fully closed side instead of the fully open side, and the electric actuator (55) for opening the choke valve and the pneumatic actuator (55a) It is connected to.
The actuator drive circuit (56) of the electric actuator (55) is linked to the key switch (57), and the pneumatic actuator (55a) is connected to the intake passage.
Before the key switch (57) is turned on to the accessory position, the biasing spring (54) keeps the choke valve (53) fully closed.
When gas fuel is selected by the fuel selection means (51), when the key switch is turned on to the accessory position, the actuator drive circuit (56) energizes the electric actuator (55), and the electric actuator (55) Starts the opening of the choke valve (53), and when the key switch (57) is turned on to the start position, the starter drive circuit (58) energizes the starter (59) and starts the engine.
During the gas fuel operation, the actuator drive circuit (56) keeps energizing the electric actuator (55) and keeps the choke valve (53) fully open.
On the other hand, when the liquid fuel is selected by the fuel selection means (51), at the time of cold start, the biasing spring (54) keeps the choke valve (53) fully closed at the initial stage of the start, and according to the temperature rise. The pneumatic actuator (55a) gradually opens the choke valve (53), and at the time of warm start, the pneumatic actuator (55a) opens the choke valve (53) in a short time at an early stage of the start.

JP 2001-280171 A

The above prior art has the following problems.
<< Problem 1 >> At the time of starting the gas fuel, the gas fuel sometimes blows through.
In the prior art, before the key switch (57) is turned on to the accessory position, the biasing spring (54) keeps the choke valve (53) fully closed. The switch (57) is turned on to the accessory position, and the electric actuator (55) starts opening the choke valve (53). When the key switch (57) is turned on to the start position, the starter drive circuit (58) energizes the starter (59) to start the engine.
For this reason, if the time from when the key switch (57) is turned on to the accessory position to when it is turned on to the start position is short, the engine starts rotating by the starter (59) with the choke valve (53) closed. Then, the gas fuel is supplied to the fuel mixer (52). When starting with gaseous fuel, if the choke valve (53) is closed, the gaseous fuel introduced into the combustion chamber will blow through the combustion chamber without burning due to lack of air. This causes the surrounding environment to be polluted by the emission of unburned gaseous fuel.

<< Problem 2 >> Electric power of the electric actuator is required during gas fuel operation.
During the gas fuel operation, the actuator drive circuit (56) keeps energizing the electric actuator (55) and keeps the choke valve (53) fully open, during which time electric power of the electric actuator (55) is required.

<< Problem 3 >> The interlocking mechanism of the choke valve is complicated.
As an interlocking mechanism of the choke valve (53), in addition to the electric actuator (55) and the urging spring (54), a pneumatic actuator (55a) is required, so that the interlocking mechanism of the choke valve (53) is complicated. .

  An object of the present invention is to provide a dual fuel engine that can solve the above problems.

(Invention of claim 1)
The contents of the invention of claim 1 are as follows.
As shown in FIG. 1, a liquid fuel and a gas fuel are selected by a fuel selecting means (1), the selected fuel is supplied to a fuel mixer (2) common to both fuels, and the fuel and air are mixed by the fuel mixer (2). In a dual fuel engine that mixes
The throttle valve (12) of the fuel mixer (2) is linked via a mechanical governor (13),
When supplying the gas fuel, the gas fuel is supplied from the gas supply source (31) to the fuel mixer (2) through the primary chamber (33) and the secondary chamber (34) of the vaporizer (32) in order. The pressure lock mechanism (36) communicates with the intake passage (35) downstream of the throttle valve (12), and when an engine stall occurs, the primary chamber (33) and the secondary chamber (33) are controlled by the pressure lock mechanism (36). (34) is cut off,
When starting with liquid fuel, make the choke valve (3) fully closed, or reduce its opening,
When starting with gas fuel, in order to open the choke valve (3) fully,
A starting gas passage (37) is led out of the primary chamber (33) of the vaporizer (32), and a starting gas valve (38) is provided in the starting gas passage (37). The valve drive circuit (39) is linked with the starter switch (7) and the fuel selection means (1),
The choke valve (3) of the fuel mixer (2) is fully urged by the urging means (4) and connected to an electric actuator (5) for closing the choke, thereby driving the actuator of the electric actuator (5). The circuit (6) is linked to the starter switch (7) and the fuel selection means (1),
Before the starter switch (7) is turned on, the biasing means (4) keeps the choke valve (3) fully open,
When the starter switch (7) is turned on, the starter drive circuit (8) energizes the starter (9),
When gas fuel is selected by the fuel selection means (1) when the starter (9) is energized, the valve drive circuit (39) energizes the starting gas valve (38) to start the engine. The gas valve (38) is opened, and the starting gas fuel is supplied from the gas supply source (31) to the fuel mixer (2) via the primary chamber (33) of the vaporizer (32) and the starting gas passage (37). Supply, even if the gas shut-off function of the pressure lock mechanism (36) works, so that the gas fuel can be started,
When the starter switch (7) is turned off, the valve drive circuit (39) stops energizing the starting gas valve (38), thereby closing the starting gas valve (38) and pressing the urging means ( In 4), keep the choke valve (3) fully open,
If liquid fuel is selected by the fuel selection means (1) when the starter (9) is energized, the actuator drive circuit (6) energizes the electric actuator (5), thereby turning on the electric actuator (5). ) Fully closes the choke valve (3) or reduces its opening,
When the starter switch (7) is turned off, the starter drive circuit (8) stops energizing the starter (9), and the actuator drive circuit (6) stops energizing the electric actuator (5). , Wherein the biasing means (4) fully opens the choke valve (3), and thereafter the biasing means (4) can keep the choke valve (3) fully open. Fuel engine.

(Claim 2)
The contents of the invention of claim 2 are as follows.
As shown in FIG. 1, in the dual fuel engine according to claim 1,
The choke valve input arm (10) interlocked with the electric actuator (5) is provided with a release wire mounting portion (11), and the choke valve (3) is manually opened and closed via the release wire mounted on the mounting portion (11). The dual fuel engine is characterized in that it can also be used.

(Inventions of claims 3 to 7)
According to a third aspect of the present invention, as shown in FIG. 1, when the throttle valve (12) of the fuel mixer (2) is interlocked via the mechanical governor (13), the liquid fuel is selected by the fuel selection means (1). In such a case, the choke valve (3) is fully closed by the electric actuator (5) and the choke valve (3) is fully opened by the urging means (4) regardless of the level of the engine temperature. And a dual fuel engine.
The invention according to claim 4 is characterized in that the electric actuator (5) is arranged between the cylinder head (14) and the intake elbow pipe (16) as shown in FIGS. Related to dual fuel engines.
According to a fifth aspect of the present invention, as shown in FIG. 3A, the air cleaner (17) is disposed at a position covering the electric actuator (5) when viewed from the cylinder head (14) side. Related to fuel engines.
According to a sixth aspect of the present invention, as shown in FIG. 3B, the intake elbow pipe (16) and the intake hose (18) are arranged at positions covering the electric actuator (5) when viewed from the side of the engine. And a dual fuel engine.
According to a seventh aspect of the present invention, as shown in FIG. 4, when viewed from the back of the engine, the breather pipe (15) is disposed at a position covering the electric actuator (5).

(Invention of claim 1)
<< Effect 1 >> At the time of starting gas fuel, blow-through of gas fuel does not easily occur.
As shown in FIG. 1, in the present invention, before the starter switch (7) is turned on, the biasing means (4) keeps the choke valve (3) fully open, and the starter switch (7) is turned on. Then, the starter drive circuit (8) energizes the starter (9).
As described above, since the choke valve (3) is fully opened at the time of starting the engine, it is difficult for the gas fuel introduced into the combustion chamber to pass through the combustion chamber without burning due to insufficient air at the time of starting the gas fuel. .
This eliminates a factor that pollutes the surrounding environment due to the release of the unburned gas fuel.

<< Effect 2 >> Electric power of the electric actuator is not required during engine operation.
As shown in FIG. 1, during operation of the engine, the choke valve (3) is kept fully open by the biasing means (4) regardless of whether gas fuel or liquid fuel is selected. No power is required for the actuator (5).

<Effect 3> The interlocking mechanism of the choke valve is simple.
As shown in FIG. 1, as the interlocking mechanism of the choke valve (3), only the urging means (4) and the electric actuator (5) are sufficient, and the interlocking mechanism of the choke valve (3) is simple.

<< Effect 4 >> The engine can be mounted on a machine whose starting operation unit is separated from the engine.
Unlike the present invention, in the case of a manual choke that opens and closes a choke valve via a release wire from a choke lever, for example, a start operation unit such as a choke lever and an engine, such as a man lift that performs a start operation while a person is riding on a wagon, In the case of a machine which is far apart, the engine cannot be mounted due to the restriction of the release wire routing.
On the other hand, in the present invention, as shown in FIG. 1, opening and closing of the choke valve (3) can be controlled only by operating the starter switch (7). Since the wiring of the electric wiring to the vehicle is not restricted by the separation, the engine can be mounted on a machine in which the starting operation unit is separated from the engine.

<< Effect 5 >> It is unlikely that the gas fuel starts to fail under cold conditions.
Unlike the present invention, in the case of an auto choke using a bimetal, the choke valve is always fully closed in cold weather, so when starting with gas fuel, the gas fuel introduced into the combustion chamber runs short of air due to lack of air and does not burn. Blows through the combustion chamber and fails to start.
On the other hand, in the present invention, as shown in FIG. 1, when the gas fuel is started, the choke valve (3) is maintained in the fully open state by the biasing means (4) even in the cold, so Gas fuel start failure is unlikely to occur.

<< Effect 6 >> Even when the gas shut-off function of the pressure lock mechanism is working, there is no problem in starting the gas fuel.
In the present invention, at the time of starting the gas fuel, the starting gas valve (38) is opened, and the gas fuel is supplied from the gas supply source (31) to the primary chamber (33) of the vaporizer (32) and the starting gas passage (37). To the fuel mixer (2), and the gas fuel can be started even if the gas shut-off function of the pressure lock mechanism (36) is working. There is no.

(Invention of claim 2)
<< Effect 7 >> When the engines of the electric choke specification and the manual choke specification are separately manufactured, a common fuel mixer can be achieved.
As shown in FIG. 1, the choke valve input arm (10) is provided with a release wire mounting portion (11) to enable the manual opening and closing of the choke valve (3). When the fuel tank is divided, the fuel mixer (2) can be shared.

<< Effect 8 >> The electric choke operation and the manual choke operation can be used together.
As shown in FIG. 1, a release wire mounting portion (11) is provided on the choke valve input arm (10) to enable the manual opening and closing of the choke valve (3), so that both the electric choke operation and the manual choke operation can be performed. Can be achieved.

(Claim 3)
<< Effect 9 >> The liquid fuel can be reliably started.
As shown in FIG. 1, when the throttle valve (12) of the fuel mixer (2) is interlocked with the mechanical governor (13), the throttle valve (12) is stopped when the engine is stopped by the biasing force (20) of the governor spring (19). Is fully opened, and the throttle valve (12) is maintained at the fully opened state even at the next start. In this case, at the time of starting the liquid fuel, suction of the liquid fuel from the slow system port by closing the throttle valve is not performed.
For this reason, unlike the present invention, when the choke valve is fully opened when the engine temperature is high, as in the case of an auto choke, the liquid fuel is hardly sucked out, and the starting failure is likely to occur.
On the other hand, in the present invention, as shown in FIG. 1, when the liquid fuel is selected by the fuel selection means (1), the choke valve by the electric actuator (5) is used regardless of the engine temperature. Since (3) is fully closed, even when the throttle valve (12) is fully open, liquid fuel is sucked out from the throttle system port and the main nozzle, and starting can be reliably performed.
Note that the fully closed time of the choke valve (3) is limited to a short time during which power is supplied to the starter (9). Therefore, even during a warm start, the liquid fuel adheres to the spark plug. No misfires occur.

(Invention of Claim 4)
<< Effect 10 >> Collision of a foreign object with the electric actuator can be prevented.
As shown in FIGS. 3 (A) and 3 (B), the electric actuator (5) is disposed between the cylinder head (14) and the intake elbow pipe (16). , Can be prevented.

(Invention of claim 5)
<< Effect 11 >> It is possible to prevent collision of foreign matter from the head cover side toward the electric actuator.
As shown in FIG. 3A, since the air cleaner (17) is arranged at a position covering the electric actuator (5) when viewed from the cylinder head (14) side, the air cleaner (17) is directed from the head cover (19) side to the electric actuator (5). It is possible to prevent collision of foreign matter.

(Invention of claim 6)
<< Effect 12 >> It is possible to prevent a foreign object from colliding from the side of the engine to the electric actuator.
As shown in FIG. 3B, when viewed from the side of the engine, the intake elbow pipe (16) and the intake hose (18) are arranged at positions covering the electric actuator (5). Collision of a foreign substance toward (5) can be prevented.

(Invention of claim 7)
<< Effect 13 >> It is possible to prevent a foreign object from colliding from behind the engine toward the electric actuator.
As shown in FIG. 4, when viewed from the back of the engine, the breather pipe (20) is arranged at a position covering the electric actuator (5). Therefore, it is possible to prevent the collision of foreign matter from behind the engine toward the electric actuator (5). Can be.

An embodiment of the present invention will be described with reference to the drawings.
This embodiment will be described using a multi-cylinder vertical dual fuel engine.

The outline of this engine is as follows.
In this engine, as shown in FIG. 1, a liquid fuel and a gas fuel are selected by a fuel selection means (1), and the selected fuel is supplied to a fuel mixer (2) common to both fuels. Mix fuel and air. Gasoline is used for the liquid fuel, and LPG (liquefied petroleum gas) is used for the gas fuel.
The throttle valve (12) of the fuel mixer (2) is interlocked via a mechanical governor (13).
When supplying the gas fuel, the gas fuel is supplied from the gas supply source (31) to the fuel mixer (2) through the primary chamber (33) and the secondary chamber (34) of the vaporizer (32) in order. The pressure lock mechanism (36) communicates with the intake passage (35) downstream of the throttle valve (12), and when an engine stall occurs, the primary chamber (33) and the secondary chamber (33) are controlled by the pressure lock mechanism (36). (34). The gas supply source (31) is a gas fuel cylinder.
When starting with liquid fuel, the choke valve (3) is fully closed, and when starting with gas fuel, the choke valve (3) is fully open.

The configuration of the fuel mixer (2) is as follows.
As shown in FIG. 1, the fuel mixer (2) includes a mixing body (22) having a venturi passage (21) provided therein, and as shown in FIG. 3 (B), a float is provided at a lower portion of the mixing body (22). A chamber (23) for storing gasoline, sucking liquid fuel from the float chamber (23) into the Venturi passage (21) by the negative pressure of the intake air passing through the Venturi passage (21), and mixing the mixture body (22) A gas fuel inlet (24) is provided in the upper part of the gas turbine, and gas fuel is sucked into the venturi passage (21) by the negative pressure of the intake air passing through the venturi passage (21).

The structure of the vaporizer (32) is as follows.
The vaporizer (32) includes a primary chamber (33) and a secondary chamber (34), and a valve between the primary chamber (33) and the secondary chamber (34) can be closed by a pressure lock mechanism (36). It has become. The pressure lock mechanism (36) communicates with the intake passage (35) on the downstream side of the throttle valve (12), and when an engine stall occurs, the pressure between the primary chamber (33) and the secondary chamber (34). Close the valve. The pressure lock mechanism (36) prevents gas fuel from leaking to the fuel mixer (2) when an engine stall occurs. A main gas passage (40) is led out of the secondary chamber (34) of the vaporizer (32), and the leading end of the main gas passage (40) communicates with a gas fuel inlet (24) of the fuel mixer (2). . A starting gas passage (37) is led out of the primary chamber (33) of the vaporizer (32), and a starting gas valve (38) is provided in the starting gas passage (37). By the starting gas passage (37), the gas fuel can be started even when the gas shut-off function of the pressure lock mechanism (36) is operated at the time of starting the gas fuel.
That is, when the throttle valve (12) of the fuel mixer (2) is linked via the mechanical governor (13), the gas fuel may be started against the drag torque of a generator or the like driven by the engine. The mechanical governor (13) is set so that the governor spring (19) fully opens the throttle valve (12) at the time of starting. At the time of gas fuel start, the choke valve (3) is also fully open, so if the throttle valve (12) is fully opened, even if cranking is performed with the starter (9), the intake negative pressure is too small and engine stall occurs. Similarly to the case, the pressure in the intake passage (35) becomes equal to or higher than a predetermined set value, the pressure lock mechanism (36) shuts off the primary chamber (33) and the secondary chamber (34), and the fuel mixer (2) ) Is not supplied with gaseous fuel, and the gaseous fuel cannot be started as it is. However, according to this embodiment, when starting the gas fuel, the starting gas valve (38) is opened, and the gas fuel is supplied from the gas supply source (31) to the primary chamber (33) of the vaporizer (32) and the starting gas. Since the fuel is supplied to the fuel mixer (2) through the passage (37) in sequence, the gas fuel can be started even when the gas shut-off function of the pressure lock mechanism (36) is working.

The configuration for selecting the fuel is as follows.
As shown in FIG. 1, a fuel mixer (2) has a gas fuel shutoff valve (25) for shutting off a gas fuel inlet (24) and a venturi passage (21), a float chamber (23) and a venturi passage (21). A liquid fuel cutoff valve (26) for shutting off the gas, and switching the gas fuel cutoff valve (25) and the liquid fuel cutoff valve (26) by the fuel selection means (1) to select fuel. I can do it. The fuel selection means (1) is a fuel switch. The lever side terminal of this fuel switch is connected to a battery (29) via a starter switch (7). The starter switch (7) is a key switch, which has an OFF position, a spark plug ON position, and a starter motor ON position. The starter motor ON position corresponds to an ON position as a starter switch. The gas fuel side terminal is connected to the gas fuel cutoff valve (25), and the liquid fuel side terminal is connected to the liquid fuel cutoff valve (26). A gas valve (42) for shutting off fuel supply from the gas supply source (31) to the primary chamber (33) of the vaporizer (32) is also connected to the gas fuel side terminal. The gas valve (42) is opened when energized and closed when not energized. A liquid fuel supply pump (27) for supplying liquid fuel from the fuel tank to the float chamber (23) is also connected to the liquid fuel side terminal.

The opening / closing interlocking mechanism of the starting gas valve (38) is as follows.
As shown in FIG. 1, the valve drive circuit (39) of the starting gas valve (38) is linked to the starter switch (7) and the fuel selection means (1). The interlocking of the valve drive circuit (39) with the starter switch (7) is performed via a starter drive circuit (8). Cooperation of the valve drive circuit (39) with the fuel selection means (1) is performed via a gas selection interlock relay (41), and the electromagnetic coil of the gas selection interlock relay (41) is connected to the fuel selection means (1). It is connected to the gas fuel side terminal. The contact of the gas selection relay (41) opens and closes the valve drive circuit (39).

The interlocking structure of the choke valve (3) is as follows.
As shown in FIG. 1, the choke valve (3) is arranged on the upstream side of the venturi passage (22), the choke valve input arm (10) is attached, and the choke valve (3) is urged to the fully open side by the urging means (4). ing. The choke valve input arm (10) is connected to an electric actuator (5) for closing a choke valve. The urging means (4) is a torque spring, and the electric actuator (5) is a linear solenoid. The actuator drive circuit (6) of the electric actuator (5) is linked to the starter switch (7) and the fuel selection means (1). The cooperation of the actuator drive circuit (6) with the starter switch (7) is performed via a starter drive circuit (8). The connection of the actuator drive circuit (6) to the fuel selection means (1) is performed via a liquid selection interlock relay (28). The electromagnetic coil of the liquid selection interlock relay (28) is connected to the liquid fuel side terminal of the fuel switching means (1). The contact of the liquid selection interlock relay (28) opens and closes the actuator drive circuit (6).

The engine start process is as follows.
As shown in FIG. 2, before the starter switch (7) is turned on in step (S1), the urging means (4) maintains the choke valve (3) fully open in step (S0). When the starter switch (7) is turned on in step (S1), the starter drive circuit (8) energizes the starter (9) in step (S2) to drive the starter (9). In step (S3), it is determined whether or not the fuel selection means (1) is on the liquid fuel side according to the selected state of the fuel selection means (1). If the determination is negative, that is, if the fuel selection means (1) If it is on the fuel side, the gas selection interlock relay (41) is turned on in step (S12), and in step (S13), power is supplied from the starter drive circuit (8) to the valve drive circuit (39), and the valve drive When the circuit (39) energizes the starting gas valve (38), the starting gas valve (38) is opened in step (S14), and the starting gas fuel is supplied from the gas supply source (31) to the vaporizer (38). 32), the fuel is supplied to the fuel mixer (2) through the primary chamber (33), the starting gas passage (37) and the main gas passage (40) in this order. When the starter switch (7) is turned off in step (S15), the starter drive circuit (8) stops energizing the starter (9) in step (S16), and the valve drive circuit (39) in step (S17). ) Stops the energization of the starting gas valve (38), thereby closing the starting gas valve (38) in step (S18), and thereafter, in step (S11), the urging means (4) starts choking. Keep valve (3) fully open. When the starter switch (7) is turned off, the starting gas valve (38) is closed. At this point, the engine speed is increased, and the pressure in the intake passage (35) is reduced to a predetermined value. The blockage between the primary chamber (33) and the secondary chamber (34) by the pressure lock mechanism (36) is released, and there is no trouble in gas fuel supply.

  If the determination in step (S3) is affirmative, that is, if the fuel selection means (1) is on the liquid fuel side, the fuel selection interlock relay (28) is turned on in step (S4), and step (S5) In step (S6), power is supplied from the starter drive circuit (8) to the actuator drive circuit (6), and the actuator drive circuit (6) supplies power to the electric actuator (5). Fully closes the choke valve (3). Thereafter, when the starter switch (7) is turned off in step (S7), the starter drive circuit (8) stops energizing the starter (9) in step (S8), and the actuator drive circuit in step (S9). (6) Stops energization of the electric actuator (5), so that the urging means (4) fully opens the choke valve (3) in step (S10), and then, in step (S11), the urging means ( 4) keeps the choke valve (3) fully open.

  In step (S4), instead of the electric actuator (5) fully closing the choke valve (3), if the engine temperature or the temperature around the engine is high, the opening of the choke valve (3) is reduced. You may just do it. In this case, the engine temperature or its surrounding temperature is detected by a temperature sensor, and the amount of power to the electric actuator (5) is changed according to the detected value to adjust the operation amount of the electric actuator (5). Just fine.

Other configurations of this engine are as follows.
As shown in FIG. 1, a release wire mounting portion (11) is provided on a choke valve input arm (10) interlocked with an electric actuator (5), and is manually operated via a release wire mounted on the mounting portion (11). The choke valve (3) can be opened and closed.

  As shown in FIG. 1, when the throttle valve (12) of the fuel mixer (2) is linked via the mechanical governor (13), when the liquid fuel is selected by the fuel selection means (1), the engine is stopped. The choke valve (3) is opened and closed regardless of the temperature.

  As shown in FIGS. 3A and 3B, the intake manifold (30) is attached to the cylinder head (14), the fuel mixer (2) is attached to the rear end of the intake manifold (30), and the fuel mixer (2) is attached. An intake elbow pipe (16) is attached, and the intake elbow pipe (16) and the air cleaner (17) are communicated by an intake hose (18) as follows. The electric actuator (5) is arranged between the cylinder head (14) and the intake elbow pipe (16). As shown in FIG. 3A, the air cleaner (17) is disposed at a position covering the electric actuator (5) when viewed from above, that is, from the cylinder head (14) side. As shown in FIG. 3B, when viewed from the side, that is, from the side of the engine, the intake elbow pipe (16) and the intake hose (18) are arranged at positions covering the electric actuator (5). As shown in FIG. 4, when viewed from the flywheel side, that is, when viewed from the back of the engine, the breather pipe (15) is disposed at a position covering the electric actuator (5).

1 is a circuit diagram of a dual fuel engine according to an embodiment of the present invention. 2 is a flowchart of a start process of the engine of FIG. 1. 3A and 3B are views for explaining an appearance of a main part of the engine shown in FIG. 1. FIG. 3A is a plan view of the main part, and FIG. 3B is a side view of the main part. FIG. 2 is a rear view of a main part of the engine of FIG. 1. FIG. 2 is a circuit diagram of a dual fuel engine according to the related art.

Explanation of reference numerals

(1) fuel selection means, (2) fuel mixer, (3) choke valve, (4) urging means, (5) electric actuator, (6) actuator drive circuit, (7) starter Switch, (8) starter drive circuit, (9) starter, (10) choke valve input arm, (11) release wire mounting part, (12) throttle valve, (13) mechanical governor, ( 14) Cylinder head, (15) Breather pipe, (16) Intake elbow pipe, (17) Air cleaner, (18) Intake hose, (31) Gas supply source, (32) Vaporizer, (33) ... primary chamber, (34) ... secondary chamber, (35) ... intake passage, (36) ... pressure lock mechanism, (37) ... starting gas passage, (38) ... starting gas valve, (39) ... valve Drive circuit.

Claims (7)

A dual fuel engine in which a liquid fuel and a gas fuel are selected by fuel selection means (1), the selected fuel is supplied to a fuel mixer (2) common to both fuels, and the fuel mixer (2) mixes the fuel and air. At
The throttle valve (12) of the fuel mixer (2) is linked via a mechanical governor (13),
When supplying the gas fuel, the gas fuel is supplied from the gas supply source (31) to the fuel mixer (2) through the primary chamber (33) and the secondary chamber (34) of the vaporizer (32) in order. The pressure lock mechanism (36) communicates with the intake passage (35) downstream of the throttle valve (12), and when an engine stall occurs, the primary chamber (33) and the secondary chamber (33) are controlled by the pressure lock mechanism (36). (34) is cut off,
When starting with liquid fuel, make the choke valve (3) fully closed, or reduce its opening,
When starting with gas fuel, in order to open the choke valve (3) fully,
A starting gas passage (37) is led out of the primary chamber (33) of the vaporizer (32), and a starting gas valve (38) is provided in the starting gas passage (37). The valve drive circuit (39) is linked with the starter switch (7) and the fuel selection means (1),
The choke valve (3) of the fuel mixer (2) is fully urged by the urging means (4) and connected to an electric actuator (5) for closing the choke, thereby driving the actuator of the electric actuator (5). The circuit (6) is linked to the starter switch (7) and the fuel selection means (1),
Before the starter switch (7) is turned on, the biasing means (4) keeps the choke valve (3) fully open,
When the starter switch (7) is turned on, the starter drive circuit (8) energizes the starter (9),
When gas fuel is selected by the fuel selection means (1) when the starter (9) is energized, the valve drive circuit (39) energizes the starting gas valve (38) to start the engine. The gas valve (38) is opened, and the starting gas fuel is supplied from the gas supply source (31) to the fuel mixer (2) via the primary chamber (33) of the vaporizer (32) and the starting gas passage (37). Supply, even if the gas shut-off function of the pressure lock mechanism (36) works, so that the gas fuel can be started,
When the starter switch (7) is turned off, the valve drive circuit (39) stops energizing the starting gas valve (38), thereby closing the starting gas valve (38) and pressing the urging means ( In 4), keep the choke valve (3) fully open,
If liquid fuel is selected by the fuel selection means (1) when the starter (9) is energized, the actuator drive circuit (6) energizes the electric actuator (5), thereby turning on the electric actuator (5). ) Completely closes the choke valve (3) or reduces its opening, and when the starter switch (7) is turned off, the starter drive circuit (8) stops energizing the starter (9), When the drive circuit (6) stops energizing the electric actuator (5), the urging means (4) fully opens the choke valve (3), and thereafter, the urging means (4) turns on the choke valve (3). The dual fuel engine is characterized in that it can be kept fully open. The dual fuel engine according to claim 1,
The choke valve input arm (10) interlocked with the electric actuator (5) is provided with a release wire mounting portion (11), and the choke valve (3) is manually opened and closed via the release wire mounted on the mounting portion (11). The dual fuel engine is characterized in that it can also be used. The dual fuel engine according to claim 1 or 2,
In linking the throttle valve (12) of the fuel mixer (2) via the mechanical governor (13),
A dual fuel engine, wherein when the liquid fuel is selected by the fuel selection means (1), the choke valve (3) is opened and closed regardless of the engine temperature. . The dual fuel engine according to any one of claims 1 to 3,
When the intake elbow pipe (16) is attached to the fuel mixer (2) and the intake elbow pipe (16) communicates with the air cleaner (17) via the intake pipe (18),
A dual fuel engine, wherein an electric actuator (5) is arranged between a cylinder head (14) and an intake elbow pipe (16). The dual fuel engine according to any one of claims 1 to 4,
A dual fuel engine, wherein an air cleaner (17) and an air cleaner (17) are arranged at a position covering the electric actuator (5) when viewed from the cylinder head (14) side. The dual fuel engine according to claim 4 or 5,
A dual fuel engine, wherein an intake elbow pipe (16) and an intake hose (18) are arranged at positions covering the electric actuator (5) when viewed from the side of the engine. The dual fuel engine according to any one of claims 1 to 6,
A dual fuel engine, wherein the breather pipe (15) is disposed at a position covering the electric actuator (5) when viewed from the back of the engine.

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