JP4048137B2 - Dual fuel engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dual fuel engine.
[0002]
[Prior art]
Conventionally, as shown in FIG. 5, as a dual fuel engine, as in the present invention, liquid fuel and gas fuel are selected by a fuel selection means (51), and the selected fuel is fed to a fuel mixer (52) common to both fuels. There is a fuel mixer (52) that mixes fuel and air (see Patent Document 1).
[0003]
This type of engine is mounted on a machine such as a manlift or a forklift that performs a lifting operation while a person is 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. .
[0004]
However, this conventional engine is different from the present invention as follows.
The choke valve (53) of the fuel mixer (52) is biased by the biasing spring (54) not to the fully open side but to the fully closed side, and the electric actuator (55) for opening the choke valve and the pneumatic actuator (55a) It is linked 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 put into 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 at the accessory position, the actuator drive circuit (56) energizes the electric actuator (55), and the electric actuator (55). Starts opening 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) to start the engine.
During gas fuel operation, the actuator drive circuit (56) maintains energization to the electric actuator (55) and keeps the choke valve (53) fully open.
On the other hand, when 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 start 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) at once in a short time at the initial stage of starting.
[0005]
[Patent Document 1]
JP-A-2001-280171
[Problems to be solved by the invention]
The above prior art has the following problems.
<Problem 1> Gas fuel may blow through when starting the gas fuel.
In the above prior art, before the key switch (57) is put into the accessory position, the biasing spring (54) keeps the choke valve (53) fully closed and gas fuel is selected. The switch (57) is put into the accessory position, and the electric actuator (55) starts to open the choke valve (53). When the key switch (57) is turned to the start position, the starter drive circuit (58) energizes the starter (59) to start the engine.
For this reason, when the time from when the key switch (57) is turned on to the start position is short, when the start switch (57) is closed, the starter (59) starts the rotation while the choke valve (53) is closed. Then, the gas fuel is supplied to the fuel mixer (52). When starting with gas fuel, if the choke valve (53) is closed, the gas fuel introduced into the combustion chamber is blown through the combustion chamber without being burned due to air shortage. This becomes a factor that pollutes the surrounding environment by releasing unburned gas fuel.
[0007]
<Problem 2> Electric power of the electric actuator is required during gas fuel operation.
During the gas fuel operation, the actuator drive circuit (56) maintains energization to the electric actuator (55) and keeps the choke valve (53) fully open, so that electric power of the electric actuator (55) is required.
[0008]
<Problem 3> The choke valve interlocking mechanism is complicated.
As the interlocking mechanism of the choke valve (53), the pneumatic actuator (55a) is required in addition to the electric actuator (55) and the biasing spring (54), so the interlocking mechanism of the choke valve (53) is complicated. .
[0009]
The subject of this invention is providing the dual fuel engine which can solve the said problem.
[0010]
[Means for Solving the Problems]
(Invention of Claim 1)
The contents of the invention of claim 1 are as follows.
As shown in FIG. 1, liquid fuel and gas fuel are selected by a fuel selection means (1), the selected fuel is supplied to a fuel mixer (2) common to both fuels, and fuel and air are fed by a fuel mixer (2). In a dual fuel engine that mixes
When starting with liquid fuel, make the choke valve (3) fully closed or reduce its opening,
When starting with gas fuel, make the choke valve (3) fully open.
The choke valve (3) of the fuel mixer (2) is urged to the fully open side by the urging means (4), and is connected to the electric actuator (5) for choke valve closing to drive 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),
If gas fuel is selected by the fuel selection means (1) when the starter (9) is energized, the choke valve (3) is kept fully open by the urging means (4),
When liquid fuel is selected by the fuel selection means (1) at the time of energization to the starter (9), the actuator drive circuit (6) energizes the electric actuator (5), so that the electric actuator (5 ) Fully 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) and the actuator When the drive circuit (6) stops energizing the electric actuator (5), the urging means (4) fully opens the choke valve (3), and then the urging means (4) is turned into the choke valve (3). Can be kept fully open ,
As shown in FIG. 3 ( A ) , the air cleaner ( 17 ) is disposed so as to cover the electric actuator ( 5 ) when viewed from the cylinder head ( 14 ) side.
As shown in FIG. 3 ( B ) , the dual fuel is characterized in that the intake elbow pipe ( 16 ) and the intake hose ( 18 ) are disposed so as to cover the electric actuator ( 5 ) when viewed from the side of the engine. engine.
[0011]
(Invention of 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 attachment portion (11), and the choke valve (3) is manually opened and closed via the release wire attached to the attachment portion (11). A dual fuel engine that can also be used.
[0012]
(Invention of Claims 3-5 )
In the invention of claim 3, as shown in FIG. 1, when the throttle valve (12) of the fuel mixer (2) is interlocked via the mechanical governor (13), liquid fuel is selected by the fuel selection means (1). When the engine temperature is high, 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). The present invention relates to a dual fuel engine characterized by that.
The invention of claim 4 is characterized in that the electric actuator (5) is disposed between the cylinder head (14) and the intake elbow pipe (16) as shown in FIGS. Relates to a dual fuel engine.
The invention of claim 5 relates to a dual fuel engine characterized in that, as shown in FIG. 4, the breather pipe (15) is disposed at a position covering the electric actuator (5) when viewed from the back of the engine .
[0013]
【The invention's effect】
(Invention of Claim 1)
<Effect 1> Gas fuel does not easily blow through when gas fuel is started.
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 when the engine is started, it is difficult for the gas fuel introduced into the combustion chamber to pass through the combustion chamber without being burned due to air shortage when starting the gas fuel. .
Thereby, the factor which pollutes the surrounding environment by discharge | release of unburned gas fuel can be eliminated.
[0014]
<Effect 2> Electric power of the electric actuator is not required during engine operation.
As shown in FIG. 1, during operation of the engine, even when either gas fuel or liquid fuel is selected, the urging means (4) keeps the choke valve (3) fully open. The power of the actuator (5) is not required.
[0015]
<Effect 3> The interlocking mechanism of the choke valve is simple.
As shown in FIG. 1, the interlocking mechanism of the choke valve (3) is sufficient if the urging means (4) and the electric actuator (5) are provided, and the interlocking mechanism of the choke valve (3) is simple.
[0016]
<Effect 4> The engine can be mounted on a machine whose start 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 from a choke lever via a release wire, for example, a start operation unit such as a choke lever and an engine such as a manlift that performs a start operation while a person is on a wagon In the case of a machine with a large distance, the engine cannot be mounted due to restrictions on the routing of the release wire.
On the other hand, in the present invention, as shown in FIG. 1, it is possible to control the opening and closing of the choke valve (3) simply by operating the starter switch (7). From the starter switch (7) to the starter (9) Since the wiring of the electric wiring 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.
[0017]
<Effect 5> Failure of gas fuel start-up in cold weather is unlikely to occur.
Unlike the present invention, in the case of an auto choke using bimetal, the choke valve is always fully closed at the time of cold, so when starting with gas fuel, the gas fuel introduced into the combustion chamber becomes short of air and does not burn. Blowing through the combustion chamber, starting failure occurs.
On the other hand, in the present invention, as shown in FIG. 1, when starting the gas fuel, the choke valve (3) is kept fully open by the urging means (4) even in cold weather. Gas fuel start failure is unlikely to occur.
<< Effect 10 >> Collision of foreign matter from the head cover side toward the electric actuator can be prevented.
As shown in FIG. 3 (A), as viewed from the cylinder head (14) side, for placing the air cleaner (17) in a position covering the electric actuator (5), extending from the head cover (19) side to the electric actuator (5) The collision of foreign matter can be prevented.
<< Effect 11 >> Collision of foreign matter from the side of the engine toward the electric actuator can be prevented.
As shown in FIG. 3 ( B ), when viewed from the side of the engine, the intake elbow pipe ( 16 ) and the intake hose ( 18 ) are disposed in a position covering the electric actuator ( 5 ) , so that the electric actuator is seen from the side of the engine. It is possible to prevent the collision of a foreign object heading for ( 5 ) .
[0018]
(Invention of Claim 2)
<Effect 6> The fuel mixer can be shared when the electric choke specification and the manual choke engine are separately manufactured.
As shown in FIG. 1, the choke valve input arm (10) is provided with a release wire mounting portion (11), which allows the choke valve (3) to be manually opened and closed. The fuel mixer (2) can be made common when making different types.
[0019]
<< Effect 7 >> Electric choke operation and manual choke operation can be used in combination.
As shown in FIG. 1, the choke valve input arm (10) is provided with a release wire mounting portion (11) to enable manual opening and closing of the choke valve (3). Can be achieved.
[0020]
(Invention of Claim 3)
<Effect 8> The liquid fuel can be reliably started.
As shown in FIG. 1, when the throttle valve (12) of the fuel mixer (2) is interlocked by a mechanical governor (13), the throttle valve (12) is stopped when the engine is stopped by the urging force (20) of the governor spring (19). May be fully opened, and the throttle valve (12) may be kept fully open at the next start-up. In this case, the liquid fuel is not sucked out from the slow system port by the throttle valve closing when the liquid fuel is started.
For this reason, unlike the present invention, if the choke valve is fully opened when the engine temperature is high, such as an auto choke, the liquid fuel is hardly sucked out, and a starting failure tends to occur.
On the other hand, in the present invention, as shown in FIG. 1, when 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 opened, liquid fuel is sucked out from the slow system port and the main nozzle, and the start can be performed reliably.
Since the choke valve (3) is fully closed for a short time during which the starter (9) is energized, liquid fuel adheres to the spark plug even during warm start. Misfire does not occur.
[0021]
(Invention of Claim 4)
<< Effect 9 >> Collision of foreign matter with the electric actuator can be prevented.
As shown in FIGS. 3 (A) and 3 (B), since the electric actuator (5) is disposed between the cylinder head (14) and the intake elbow pipe (16), the collision of foreign matter with the electric actuator (5) is prevented. Can be prevented.
[0024]
(Invention of Claim 5 )
<< Effect 12 >> Collision of foreign matter from behind the engine toward the electric actuator can be prevented.
As shown in FIG. 4, since the breather pipe (20) is disposed at a position covering the electric actuator (5) when viewed from the back of the engine, it is possible to prevent the collision of foreign matters from the back of the engine toward the electric actuator (5). Can do.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
In this embodiment, a multi-cylinder vertical dual fuel engine will be described.
[0026]
The outline of this engine is as follows.
In this engine, as shown in FIG. 1, liquid fuel and gas fuel are selected by a fuel selection means (1), the selected fuel is supplied to a fuel mixer (2) common to both fuels, and the fuel mixer (2) To mix fuel and air. Gasoline is used as the liquid fuel, and LPG (liquefied petroleum gas) is used as the gas fuel.
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.
[0027]
The configuration of the fuel mixer (2) is as follows.
As shown in FIG. 1, the fuel mixer (2) is provided with a mixing body (22) having a venturi passage (21) provided therein, and, as shown in FIG. 3 (B), floats below the mixing body (22). A chamber (23) is provided, in which gasoline is stored, and by the negative pressure of the intake air passing through the venturi passage (21), liquid fuel is sucked out from the float chamber (23) into the venturi passage (21), and the mixing body (22) A gas fuel inlet (24) is provided at the upper portion of the gas passage, and gas fuel is sucked into the venturi passage (21) by the negative pressure of the intake air passing through the venturi passage (21).
[0028]
The configuration for selecting the fuel is as follows.
As shown in FIG. 1, the fuel mixer (2) includes a gas fuel shutoff valve (25) that shuts off the gas fuel inlet (24) and the venturi passage (21), a float chamber (23), and the venturi passage (21). A liquid fuel shut-off valve (26) for switching between the gas fuel shut-off valve (25) and the liquid fuel shut-off valve (26) by the fuel selection means (1) to select the fuel. It can be done. The fuel selection means (1) is a fuel changeover switch. The lever side terminal of this fuel changeover switch is connected to the battery (29) via the starter switch (7). The starter switch (7) is a key switch, and there are an OFF position, a spark plug ON position, and a starter motor ON position. The starter motor ON position corresponds to the 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 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.
[0029]
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), is attached with a choke valve input arm (10), and is urged to the fully open side by the urging means (4). ing. The choke valve input arm (10) is connected to the electric actuator (5) for closing the choke valve. The biasing 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 actuator drive circuit (6) is linked to the starter switch (7) via the starter drive circuit (8). The actuator drive circuit (6) is linked to the fuel selection means (1) via a fuel selection linkage relay (28). The electromagnetic coil of the fuel selection interlocking relay (28) is connected to the liquid fuel side terminal of the fuel switching means (1). The contact of the fuel selection interlock relay (28) opens and closes the actuator drive circuit (6).
[0030]
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) and drives the starter (9) in step (S2). In step (S3), it is determined whether or not the fuel selection means (1) is on the liquid fuel side according to the selection state of the fuel selection means (1). If the determination is negative, that is, the fuel selection means (1) is gas. If it is on the fuel side, the urging means (4) keeps the choke valve (3) fully open in step (S11).
[0031]
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 ), The actuator drive circuit (6) is energized from the starter drive circuit (8), and the actuator drive circuit (6) energizes the electric actuator (5), so that the electric actuator (5) is obtained in step (S6). 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), and in step (S10), the urging means (4) fully opens the choke valve (3), and then in step (S11) the urging means ( 4) keeps the choke valve (3) fully open.
[0032]
In step (S4), instead of the electric actuator (5) fully closing the choke valve (3), if the engine temperature or the surrounding temperature is high, the opening of the choke valve (3) is reduced. You can just do it. In this case, the engine temperature or its surrounding temperature is detected by a temperature sensor, and the amount of power supplied to the electric actuator (5) is changed according to the detected value so that the operation amount of the electric actuator (5) can be adjusted. That's fine.
[0033]
Other configurations of this engine are as follows.
As shown in FIG. 1, a choke valve input arm (10) interlocked with an electric actuator (5) is provided with a release wire attachment portion (11), and is manually operated via a release wire attached to the attachment portion (11). The choke valve (3) can be opened and closed.
[0034]
As shown in FIG. 1, when liquid fuel is selected by the fuel selection means (1) when the throttle valve (12) of the fuel mixer (2) is interlocked via the mechanical governor (13), the engine The choke valve (3) is opened / closed regardless of the temperature.
[0035]
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. The intake elbow pipe (16) is attached, and the intake elbow pipe (16) and the air cleaner (17) are communicated with each other through the intake hose (18) as follows. The electric actuator (5) is disposed 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 the upper side, that is, from the cylinder head (14) side. As shown in FIG. 3 (B), the intake elbow pipe (16) and the intake hose (18) are arranged at a position covering the electric actuator (5) when viewed from the side, that is, from the side of the engine. As shown in FIG. 4, the breather pipe (15) is disposed at a position covering the electric actuator (5) when viewed from the flywheel side, that is, from the back of the engine.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of a dual fuel engine according to an embodiment of the present invention.
FIG. 2 is a flowchart of an engine start process of FIG. 1;
3 is a diagram for explaining the external appearance of the main part of the engine of FIG. 1, FIG. 3 (A) is a plan view of the main part, and FIG. 3 (B) is a side view of the main part.
4 is a main part rear view of the engine of FIG. 1; FIG.
FIG. 5 is a circuit diagram of a dual fuel engine according to the prior art.
[Explanation of symbols]
(1) ... fuel selection means, (2) ... fuel mixer, (3) ... choke valve, (4) ... biasing 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) ... Blazer pipe, (16) ... Intake elbow pipe, (17) ... Air cleaner, (18) ... Intake hose.

Claims (5)

A dual fuel engine in which liquid fuel and gas fuel are selected by a fuel selection means (1), the selected fuel is supplied to a fuel mixer (2) common to both fuels, and fuel and air are mixed by the fuel mixer (2) In
When starting with liquid fuel, make the choke valve (3) fully closed or reduce its opening,
When starting with gas fuel, make the choke valve (3) fully open.
The choke valve (3) of the fuel mixer (2) is urged to the fully open side by the urging means (4), and is connected to the electric actuator (5) for choke valve closing to drive 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),
If gas fuel is selected by the fuel selection means (1) when the starter (9) is energized, the choke valve (3) is kept fully open by the urging means (4),
When liquid fuel is selected by the fuel selection means (1) at the time of energization to the starter (9), the actuator drive circuit (6) energizes the electric actuator (5), so that the electric actuator (5 ) Fully 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) and the actuator When the drive circuit (6) stops energizing the electric actuator (5), the urging means (4) fully opens the choke valve (3), and then the urging means (4) is turned into the choke valve (3). Can be kept fully open ,
When viewed from the cylinder head ( 14 ) side, the air cleaner ( 17 ) is disposed at a position covering the electric actuator ( 5 ) ,
A dual fuel engine characterized in that an intake elbow pipe ( 16 ) and an intake hose ( 18 ) are arranged at a position covering the electric actuator ( 5 ) when viewed from the side of the engine. The dual fuel engine of claim 1, wherein
The choke valve input arm (10) interlocked with the electric actuator (5) is provided with a release wire attachment portion (11), and the choke valve (3) is manually opened and closed via the release wire attached to the attachment portion (11). A dual fuel engine that can also be used. The dual fuel engine according to claim 1 or 2,
When interlocking the throttle valve (12) of the fuel mixer (2) via the mechanical governor (13),
A dual fuel engine characterized in that 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,
Attach the intake elbow pipe (16) to the fuel mixer (2), and connect the intake elbow pipe (16) and the air cleaner (17) with the intake pipe (18).
A dual fuel engine comprising an electric actuator (5) disposed 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, characterized in that 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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