JP4168034B2 - Spark ignition engine - Google Patents

Description

  The present invention relates to a spark ignition engine, and more particularly to a spark ignition engine that can prevent engine start failure.

As a conventional spark ignition engine, as in the present invention, gas fuel is supplied from a gas fuel supply source to a fuel mixer, a pressure lock valve is provided between the gas fuel supply source and the fuel mixer, and this pressure lock valve is used as a fuel. Some of the mixers communicate with the intake downstream of the throttle valve, and when an engine stall occurs, the pressure lock valve shuts off the fuel supply to the fuel mixer based on the fact that the intake negative pressure downstream of the throttle valve decreases.
This type of spark ignition engine has an advantage that the fuel supply to the fuel mixer is interrupted at the time of the stall and gas fuel can be prevented from leaking from the fuel mixer while the engine is stopped.

  However, the conventional spark ignition type engine has a problem because the negative pressure on the downstream side of the intake of the throttle valve cannot be controlled when the engine is started.

The above prior art has the following problems.
<Problem> The engine may fail to start.
Since the intake negative pressure on the downstream side of the throttle valve cannot be controlled when the engine is started, if the throttle valve opening is large, the intake negative pressure on the downstream side of the throttle valve during cranking at the start of the engine May not increase, and the pressure lock valve may continue to shut off the fuel supply and fail to start the engine.

<Problem> Engine start-up failures are particularly likely to occur during cold weather or when an external load is connected.
When the engine is cold, the engine oil viscosity increases, so the internal load of the engine increases, and the resistance applied to the crankshaft increases when the engine is started. Even when an external load is connected, the resistance applied to the crankshaft when the engine is started increases. In such a case, the cranking speed when starting the engine is also slowed down, so even if the opening of the throttle valve is reduced to some extent, the intake negative pressure on the intake downstream side of the throttle valve does not increase, and the pressure lock The valve continues to shut off the fuel supply, and engine start failure is likely to occur.

  An object of the present invention is to provide a spark ignition engine capable of solving the above-described problems, that is, a spark ignition engine capable of preventing a failure of engine start.

Invention specific matters of the invention according to claim 1 are as follows.
As illustrated in FIG. 1, gas fuel is supplied from a gas fuel supply source (1) to a fuel mixer (2), and a pressure lock valve (3) is provided between the gas fuel supply source (1) and the fuel mixer (2). ) And the pressure lock valve (3) communicates with the intake downstream of the throttle valve (4) of the fuel mixer (2), and when an engine stall occurs, the intake negative pressure downstream of the throttle valve (4) is reduced. In a spark ignition engine in which the pressure lock valve (3) cuts off the fuel supply to the fuel mixer (2),
A choke valve (5) is provided on the intake upstream side of the fuel mixer (2), the choke valve (5) is linked to a valve actuator (6), and the valve actuator (6) is connected to the control means (7). Link this control means (7) with the engine speed detection means (8),
When the engine is started, the control of the control means (7) allows the release of the fuel supply by the pressure lock valve (3) to be released by decreasing the opening of the choke valve (5) as the cranking speed is slower. A spark ignition engine characterized by that.

(Invention according to Claim 1)
<Effect> Failure to start the engine can be prevented.
Since the opening of the choke valve (5) is controlled by the control means (7) when the engine is started, the cutoff of the fuel supply by the pressure lock valve (3) can be released. Failure to start the engine due to (3) can be prevented.

<Effect> Engine start-up failure is unlikely to occur even during cold weather or when an external load is connected.
When the engine is started, the control means (7) controls the lower the cranking speed, so the opening of the choke valve (5) becomes smaller. Therefore, even when the cranking speed is slow, the intake downstream side of the throttle valve (4) The intake negative pressure of the engine increases, so that the shutoff of the fuel supply by the pressure lock valve (3) can be reliably released, and the engine start-up failure is unlikely to occur. For this reason, engine start-up failure is unlikely to occur even during cold weather when the cranking speed is slow at engine start-up or when an external load is connected.

(Invention according to Claim 2)
In addition to the effect of the invention according to claim 1, the following effect is achieved.
<Effect> It is possible to prevent engine start failure due to liquid fuel.
When the engine is started by selecting liquid fuel, the control means (7) determines that the choke valve (5) is fully closed based on the engine temperature (T0) and the first valve opening before starting the engine. The angle (K1), the second valve opening angle (K2), the transition time (T01) (T12) to these, and the maintenance time (T1) (T2) are set, and when the engine is started, the control means (7) Since the choke valve (5) is controlled on the basis of the above setting, the opening degree of the fine choke valve (5) corresponding to the engine temperature can be adjusted and the engine start failure due to liquid fuel can be prevented. it can.

(Invention according to claims 3 to 6)
In addition to the effect of the invention according to claim 2, the following effect is achieved.
<Effect> It is possible to prevent engine start failure due to cold liquid fuel.
As the engine temperature is lower, the control means (7) sets the fully closed maintenance time (T0) longer, or sets the first valve opening angle (K1) and the second valve opening angle (K2) smaller, or The first valve opening transition time (T01) and the second valve opening transition time (T12) are set longer, or the first valve opening maintenance time (T1) and the second valve opening maintenance time (T2) are set longer. For this reason, the tendency of the choke valve (5) to close is increased during cold weather, and failure of engine start due to liquid fuel during cold weather can be prevented.

  Embodiments of the present invention will be described with reference to the drawings. 1 to 6 are diagrams for explaining a spark ignition type engine according to an embodiment of the present invention. In this embodiment, a dual fuel spark ignition type using a liquid fuel (gasoline) and a gas fuel (natural gas) selectively used. The engine will be described.

The outline of the embodiment of the present invention is as follows.
As shown in FIG. 1, the fuel supply device of this engine includes a fuel mixer (2). The fuel mixer (2) includes a venturi passage (11), a throttle valve (4) is provided on the intake downstream side of the venturi passage (11), and the throttle valve (4) is regulated through a mechanical governor (16). Linked to the lever (17). The mechanical governor (16) swings the governor lever (22) by an unbalanced force between the governor force (19) of the governor spring (18) and the governor force (21) of the governor weight (20), and the throttle valve (4). Adjust the opening.

The configuration of the liquid fuel supply means is as follows.
As shown in FIG. 1, the liquid fuel nozzle (12) and the gas fuel nozzle (13) face the venturi passage (11) of the fuel mixer (2). The liquid fuel nozzle (12) communicates with a float chamber (23) below the fuel mixer (2) shown in FIG. The float chamber (23) communicates with a liquid fuel tank (not shown) via a liquid fuel pump (24) shown in FIG. The float chamber (23) is provided with a liquid fuel nozzle valve (14) so that the supply of liquid fuel from the liquid fuel nozzle (12) can be shut off.

The configuration of the gas fuel supply means is as follows.
As shown in FIG. 1, the gas fuel nozzle (13) is connected to the gas fuel supply source (1) through the vaporizer (26). The vaporizer (26) includes a primary chamber (26a) and a secondary chamber (26b), and sequentially vaporizes the liquefied gas fuel. A gas fuel valve (27) is provided between the vaporizer (26) and the gas fuel supply source (1) so that the gas fuel supply to the vaporizer (26) can be shut off. Further, a gas fuel nozzle valve (15) is provided in the fuel mixer (2) so that the supply of gas fuel from the gas fuel nozzle (13) can be shut off.

Means for selecting the fuel are as follows.
As shown in FIG. 1, the liquid fuel pump (24), the liquid fuel nozzle valve (14), the gas fuel valve (27), and the gas fuel nozzle valve (15) are connected to the fuel selection means via the control means (7). Linked to (9). When liquid fuel is selected by the fuel selection means (9), the liquid fuel pump (24) is operated under the control of the control means (7), the liquid fuel nozzle valve (14) is opened, and the venturi passage ( The liquid fuel is supplied from the liquid fuel nozzle (12) to the venturi passage (11) with the negative pressure of the intake air passing through 11). In this case, the control of the control means (7) closes the gas fuel valve (27) and the gas fuel nozzle valve (15) so that the gas fuel is not supplied to the venturi passage (11). When gas fuel is selected by the fuel selection means (9), the gas fuel valve (27) and the gas fuel nozzle valve (15) are opened by the control of the control means (7), and the venturi passage (11) is opened. The gas fuel is supplied from the gas fuel nozzle (13) to the venturi passage (11) with the negative pressure of the intake air passing through. In this case, under the control of the control means (7), the liquid fuel pump (24) is stopped, the liquid fuel nozzle valve (14) is closed, and the liquid fuel is not supplied to the venturi passage (11).

The configuration of the engine starting means is as follows.
The key switch (28), the starter (29), and the engine rotation speed detection means (8) are linked to the control means (7). When the key switch (28) is turned on at the start position, the starter (29) is activated and engine cranking is started. When the key switch (28) is removed from the start position, the starter (29) stops operating. Further, when the engine rotation speed detection means (8) detects a predetermined start completion rotation speed, the operation of the starter (29) is stopped under the control of the control means (7).

In this embodiment, in order to prevent gas leakage at the time of gas fuel operation, the following configuration is adopted.
That is, as shown in FIG. 1, a pressure lock valve (3) is provided between the gas fuel supply source (1) and the fuel mixer (2), and this pressure lock valve (3) is used as a throttle of the fuel mixer (2). The pressure lock valve (3) supplies fuel to the fuel mixer (2) based on the fact that the intake negative pressure downstream of the throttle valve (4) is reduced when an engine stall occurs. I try to block it. The pressure lock valve (3) is disposed between the primary chamber (26a) and the secondary chamber (26b) of the vaporizer (26).

In this embodiment, the following means are adopted in order to eliminate the problem of failure in starting the engine with the pressure lock valve when starting the gas fuel.
That is, as shown in FIG. 1, a choke valve (5) is provided on the intake upstream side of the fuel mixer (2), and this choke valve (5) is linked to the valve actuator (6). 6) is linked to the control means (7), this control means (7) is linked to the engine rotation speed detection means (8), and the cranking speed is controlled by the control means (7) when the engine is started with gas fuel. The later, the lower the opening of the choke valve (5), so that the shutoff of the fuel supply by the pressure lock valve (3) can be released.

In this embodiment, the following means are adopted as means for preventing failure of engine start due to liquid fuel.
That is, as shown in FIG. 1, when the control means (7) is linked to the fuel selection means (9) and the engine temperature detection means (10) to select the liquid fuel and start the engine, Further, the control means (7) determines the choke valve (5) fully closed maintaining time (T0), the first valve opening angle (K1), and the fully closed (K0) from FIG. The first valve opening transition time (T01) for shifting to one valve opening angle (K1), the first valve opening maintaining time (T1) for maintaining the first valve opening angle (K1), and the first valve opening angle (K1) ) Larger than the second valve opening angle (K2), the second valve opening transition time (T12) for shifting from the first valve opening angle (K1) to the second valve opening angle (K2), and the second valve opening angle. A second valve opening maintenance time (T2) for maintaining (K2) is set. Although the coolant temperature detection means is used as the engine temperature detection means (10), an oil temperature detection means for engine oil, an air temperature detection means for cooling air, and the like may be used.

  As shown in FIG. 6, when the engine is started, the control means (7) based on the above setting controls the choke valve (5) to be fully closed (K0) and maintained for the fully closed maintenance time (T0). The first valve opening angle (K1) is opened over the first valve opening transition time (T01), the first valve opening angle (K1) is maintained for the first valve opening maintaining time (T1), and the second valve opening angle. The valve is opened over the second valve opening transition time (T12) until (K2), and the second valve opening angle (K2) is maintained for the second valve opening maintaining time (T2). Then, the choke valve (5) is fully opened (K3) over a predetermined fully open transition time (T23).

In this embodiment, the following means is employed in order to prevent engine start failure due to liquid fuel during cold weather.
That is, as the engine temperature is lower, the control means (7) sets the fully closed maintaining time (T0) longer and sets the first valve opening angle (K1) and the second valve opening angle (K2) to be smaller. In addition, the first valve opening transition time (T01) and the second valve opening transition time (T12) are set longer, and the first valve opening maintenance time (T1) and the second valve opening maintenance time (T2) are lengthened. Set.

The specific control procedure when starting the engine is as follows.
As shown in FIG. 3, when the key switch (28) is put into the start position in step (S1), the control means (7) determines in step (S2) whether or not the fuel selection means (9) is on the liquid fuel side. To do. If the determination is affirmative, the control means (7) determines whether or not the water temperature is lower than a predetermined temperature in step (S3). If the determination is affirmative, in step (S4), the control means (7) determines whether the choke valve (5) is fully closed (T0) and the first valve opening angle (K1) according to the water temperature. , A first valve opening transition time (T01) for shifting from fully closed (K0) to the first valve opening angle (K1), and a first valve opening maintaining time (T1) for maintaining the first valve opening angle (K1). , Second valve opening angle (K2), second valve opening transition time (T12) during which the first valve opening angle (K1) shifts to the second valve opening angle (K2), and second valve opening angle (K2) Is set to the second valve opening maintenance time (T2).

  Next, in step (S5), under the control of the control means (7), the choke valve (5) is fully opened (K3), and after the reference position of the choke valve (5) is detected, the choke valve (5) is fully opened. Close (K0), and in step (S6), the starter (29) is operated under the control of the control means (7), and it is determined whether or not the start complete rotation speed is detected in step (S7). If the determination is positive and the determination is affirmative, the operation of the starter (29) is stopped under the control of the control means (7) in step (S8). If the determination in step (S7) is negative, the operation of the starter (29) is continued under the control of the control means (7) until the determination is affirmed.

  After stopping the operation of the starter (29) in step (S8), in step (S9), the control means (7) controls the choke valve (5) to be fully closed (K0) and fully closed (T0). In step (S10), the first valve opening angle (K1) is opened over the first valve opening transition time (T01), and the first valve opening angle (K1) is maintained for the first valve opening maintaining time. (T1) is maintained, and in step (S11), the valve is opened over the second valve opening transition time (T12) until the second valve opening angle (K2), and the second valve opening angle (K2) is opened. It is maintained only for the maintenance time (T2), and in step (S12), it is fully opened (K3) over a predetermined full opening transition time (T23), and the control of the choke valve (5) is finished while maintaining the full opening (K3). .

  If the determination in step (S3) is negative, that is, if the water temperature is equal to or higher than the predetermined temperature, the choke valve (5) is fully opened (K3) under the control of the control means (7) in step (S13). In step (S14), the starter (29) is operated, and in step (S15), the control means (7) determines whether or not the start completion rotational speed is detected. If the determination is affirmative, step (S14) At (S16), the control of the control means (7) stops the operation of the starter (29), and the control of the choke valve (5) is terminated while the choke valve (5) is kept fully open. If the determination in step (S15) is negative, the operation of the starter (29) is continued under the control of the control means (7) until the determination is affirmed.

  If the determination in step (S2) is negative, that is, if the fuel selection means (9) is on the gas fuel side, the control means (7) is in step (S17) as shown in FIG. Under the control, the choke valve (5) is fully opened (K3) and then set to a predetermined initial valve opening angle. Next, in step (S18), the starter (29) is operated by the control of the control means (7), the engine speed is detected in step (S19), and in step (S20), the control means (7) By the control, the opening degree of the choke valve (5) is increased as the cranking rotation speed is increased. Next, the control means (7) determines whether or not the start completion rotational speed is detected in step (S21). If the determination is affirmative, the control means (7) is controlled in step (S22). Thus, the operation of the starter (29) is stopped, and the control of the choke valve (5) is terminated while the choke valve (5) is kept fully open. If the determination in step (S21) is negative, the process returns to step (S19), and the operation of the starter (29) is controlled by the control means (7) until the determination in step (S21) is affirmed. Continue.

1 is a schematic diagram of a fuel supply device for a spark ignition engine according to an embodiment of the present invention. It is a front view of the fuel mixer used with the apparatus of FIG. This is the first half of the flow chart of starting control used in the apparatus of FIG. This is the latter half of the flow chart of the start control used in the apparatus of FIG. Among the flowcharts of the start control used in the apparatus of FIG. Of the time chart of the start control used in the apparatus of FIG.

Explanation of symbols

(1) Gas fuel supply source
(2) Fuel mixer
(3) Pressure lock valve
(4) Throttle valve
(5) Choke valve
(6) Valve actuator
(7) Control means
(8) Engine rotation speed detection means
(9) Fuel selection means
(10) Engine temperature detection means
(K0) Fully closed
(K1) First valve opening angle
(K2) Second valve opening angle
(T0) Fully closed maintenance time
(T01) First valve opening transition time
(T1) First valve maintenance time
(T12) Second valve opening transition time
(T2) Second valve opening maintenance time

Claims (6)

Gas fuel is supplied from the gas fuel supply source (1) to the fuel mixer (2), and a pressure lock valve (3) is provided between the gas fuel supply source (1) and the fuel mixer (2). (3) communicates with the intake valve downstream of the throttle valve (4) of the fuel mixer (2), and when an engine stall occurs, the pressure lock valve (3) In a spark ignition engine in which the fuel supply to the fuel mixer (2) is cut off,
A choke valve (5) is provided on the intake upstream side of the fuel mixer (2), the choke valve (5) is linked to a valve actuator (6), and the valve actuator (6) is connected to the control means (7). The control means (7) is linked to the engine speed detection means (8),
When the engine is started, the control of the control means (7) allows the release of the fuel supply by the pressure lock valve (3) to be released by decreasing the opening of the choke valve (5) as the cranking speed is slower. A spark ignition engine characterized by that. The spark ignition engine according to claim 1,
In selecting and using gas fuel and liquid fuel by the fuel selection means (9),
When the control means (7) is linked to the fuel selection means (9) and the engine temperature detection means (10) to select the liquid fuel and start the engine,
Before starting the engine, the control means (7) is based on the engine temperature,
Choke valve (5) fully closed maintenance time (T0),
The first valve opening angle (K1), the first valve opening transition time (T01) for shifting from the fully closed (K0) to the first valve opening angle (K1), and the first valve opening angle (K1) are maintained. 1 valve opening maintenance time (T1),
A second valve opening angle (K2) larger than the first valve opening angle (K1), and a second valve opening transition time (T12) during which the first valve opening angle (K1) is shifted to the second valve opening angle (K2). And a second valve opening maintenance time (T2) for maintaining the second valve opening angle (K2),
When the engine is started, the control means (7) based on the above setting controls the choke valve (5) to be fully closed (K0) and maintained for the fully closed maintaining time (T0) until the first valve opening angle (K1). The valve is opened over the first valve opening transition time (T01), the first valve opening angle (K1) is maintained for the first valve opening maintaining time (T1), and the second valve opening transition is performed until the second valve opening angle (K2). A spark ignition engine characterized by opening the valve over time (T12) and maintaining the second valve opening angle (K2) for the second valve opening maintaining time (T2). The spark ignition engine according to claim 2,
A spark ignition engine characterized in that, as the engine temperature is lower, the control means (7) sets the fully closed maintaining time (T0) longer. The spark ignition type engine according to claim 2 or 3,
A spark ignition engine characterized in that the control means (7) sets the first valve opening angle (K1) and the second valve opening angle (K2) to be smaller as the engine temperature is lower. In the spark ignition engine according to any one of claims 2 to 4,
A spark ignition engine characterized in that the control means (7) sets the first valve opening transition time (T01) and the second valve opening transition time (T12) longer as the engine temperature is lower. The spark ignition type engine according to any one of claims 2 to 5,
A spark ignition engine characterized in that the control means (7) sets the first valve opening maintaining time (T1) and the second valve opening maintaining time (T2) longer as the engine temperature is lower.

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