JPH0914057A - Starting time fuel supplying device for gas engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To contrive reliable starting by holding the air-fuel ratio of mixture in a sub combustion chamber within the combustible range for a specified time in starting of the engine under any condition. SOLUTION: In a gas engine provided with a fuel supplying path 1 communicated with a main combustion chamber and a fuel supplying path 13 communicated with a sub combustion chamber, a slow open valve 15a to be opened at the same time that the starting operation of the engine is started, and having the valve opening to be increased in proportion to the passage of time into the full opening is provided on the way of the fuel supplying path extending to the sub combustion chamber in a starting time fuel supplying device. A bypass pipe for gas is provided between an air-fuel, ratio controller 4 of the fuel supplying path extending to the main combustion chamber and a turbo supercharger 5, a main chamber slow open valve provided with an inherent function is provided on the bypass pipe, a sub chamber slow open valve 15a is provided on the fuel supplying path extending to the sub combustion chamber, and both slow open valves are controlled by a valve opening electric controller 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply device for starting a gas engine.

[0002]

2. Description of the Related Art Fuel gas for gas engines has a relatively narrow air-fuel ratio range in which combustion by flame propagation in a cylinder is possible (a typical 13A gas has a volume of 4 to 14).
%). Therefore, an air-fuel ratio control device such as a venturi is provided in the middle of the fuel supply path to the combustion chamber so that the air-fuel mixture having an appropriate air-fuel ratio can be obtained by the control device in a steady operating state. Have control.

However, when the engine is in the cranking state at the time of starting, the rotation speed of the engine is low, and the flow velocity of the gas passing through the air-fuel ratio control device is low. For this reason, the air-fuel ratio control device does not function sufficiently, the air-fuel ratio of the air-fuel mixture supplied into the combustion chamber may become unstable and deviate from the combustible range, and ignition may not be possible and start may be impossible. .

FIG. 2 is a structural explanatory view of the periphery of a combustion chamber of a gas engine having an auxiliary combustion chamber, and FIG. 8 is a structural explanatory diagram of a conventional example of a fuel supply path. In FIG. 8, 1 is a fuel supply path to the main combustion chamber, 2 is an open / close valve, 3 is an air cleaner, 4
Is an air-fuel ratio control device, 5 is an exhaust turbocharger, 8 is a mixture cooler, 9 is an intake manifold, 10 is a cylinder head,
Reference numeral 12 is a gas branch pipe supplied to the auxiliary combustion chamber, 13 is a fuel supply path to the auxiliary combustion chamber, and 14 is an opening / closing valve. In FIG.
10 is a cylinder head, 20 is an auxiliary combustion chamber, 21 is a mouthpiece of the auxiliary combustion chamber, 22 is a nozzle provided in the mouthpiece, 23 is a main combustion chamber, 24 is a piston, and 25 is an ignition plug.

The above-mentioned accident in which the air-fuel mixture cannot be ignited and cannot be started often occurs in the case of a gas engine having a sub-combustion chamber. This will be described with reference to FIGS. 8 and 2. Main combustion chamber 2 formed at the head of piston 24
An air-fuel ratio control device 4 is arranged in a fuel supply path 1 to the air conditioner 3 to mix a lean air-fuel ratio by air sucked through an air cleaner 3 and a gas supplied through an on-off valve 2. Air is generated, and the air-fuel mixture is supplied to the main combustion chamber 23 from the air supply holes of each cylinder head 10 through the air supply manifold 9 via the exhaust turbocharger 5 and the air-fuel mixture cooler 8.

On the other hand, the sub-combustion chamber 20 is opened simultaneously with the start of the engine starting operation, and as shown in the characteristic diagram of FIG. Is supplied to the auxiliary combustion chamber 20 from the main combustion chamber 23 through the nozzle 22 of the mouthpiece 21 of the auxiliary combustion chamber and flows into the auxiliary combustion chamber 20. It has become the theoretical air-fuel ratio.

[0007]

When the lean air-fuel mixture flowing from the main combustion chamber 23 in the auxiliary combustion chamber 20 and the gas supplied through the on-off valve 14 are further mixed as described above. The air-fuel ratio in the auxiliary combustion chamber 23 changes as shown in FIG. 10 over time. Fig. 10 shows 1 as fuel gas
It is an explanatory diagram of the time shift of the combustible air-fuel ratio (the range of 4 to 14% in volume for 13A gas) when 3A gas is used, and as shown in the shift (e) when the opening degree of the on-off valve 14 is large. When the air-fuel ratio becomes excessively large and the opening is small, the air-fuel ratio becomes too small as shown in the transition (c), and in any case, ignition cannot be performed and the engine cannot be started.

Ignition can be performed if the opening degree of the on-off valve 14 is set to change (d), but since the supply amount of gas changes due to the influence of fluctuations in gas pressure and temperature,
In many cases, the transition is made to (c) or (e). There is also a means for providing an air-fuel ratio control device in the middle of the fuel supply path 13 to the auxiliary combustion chamber 20, but since the flow velocity of the gas passing through the air-fuel ratio control device is slow in the cranking state at the start,
The function cannot be fully exerted.

The object of the present invention is to solve the above problems, and under any condition, the air-fuel ratio of the air-fuel mixture in the auxiliary combustion chamber is always kept within the combustible range for a certain period of time when the engine is started, so that the engine can be started reliably. A fuel supply device for starting a gas engine is provided.

[0010]

In a fuel supply device for starting a gas engine according to a first aspect of the present invention, an exhaust gas turbocharger 5 uses a lean mixture of air and gas generated by an air-fuel ratio control device 4.
In a gas engine having a fuel supply path 1 that leads to the main combustion chamber 23 via a fuel supply path 13 that guides gas to the auxiliary combustion chamber 20, a fuel supply path 1 that leads to the auxiliary combustion chamber
3 is characterized in that a slow open valve 15 is provided which starts opening at the same time as the start of the engine start operation and increases the valve opening with the lapse of time to fully open.

In the fuel supply device for starting the gas engine according to the second aspect of the present invention, the lean air-fuel mixture produced by the air-fuel ratio control device 4 is introduced into the main combustion chamber 23 through the exhaust turbocharger 5. In the gas engine including the fuel supply path 1 and the fuel supply path 13 that guides the gas to the auxiliary combustion chamber 20,
A bypass pipe 26 for bypassing gas is provided between the air-fuel ratio control device 4 and the turbocharger 5 in the fuel supply path 1 leading to the main combustion chamber, and the bypass pipe 26 is opened at the same time when the engine start operation is started. Is provided with a main chamber slow open valve 27 that starts to close and closes when the operating state of the engine reaches a predetermined state by increasing the valve opening with the passage of time and supplying fuel to the auxiliary combustion chamber. A sub chamber slow open valve 16 that starts opening after the main chamber slow open valve 27 starts closing and then increases the valve opening with the passage of time to fully open is provided on the path 13, and a signal indicating the operating condition of the engine. It is characterized in that a valve opening electronic control unit 17 for inputting the above and outputting a valve opening setting signal to both the slow open valves 16 and 27 is provided.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 is a structural explanatory view of a fuel supply path of a six-cylinder gas engine according to a first embodiment of the first invention. The configuration and operation will be described with reference to FIGS. 1 and 2. The fuel gas supplied from a supply source (not shown) reaches the air-fuel ratio control device 4 through the on-off valve 2 and is mixed with the air taken in from the air cleaner 3 to generate a lean air-fuel ratio mixture. The air-fuel mixture is supplied from the exhaust turbocharger 5 to the main combustion chamber 23 via the air-fuel mixture cooler 8 and the air-supply manifold 9 through the air-intake holes of each cylinder head 10.

Gases supplied from a supply source (not shown) are simultaneously supplied to the auxiliary combustion chamber 23 through the fuel supply path 13
With the solenoid valve configuration as shown in FIG. 3 (a), the valve is opened at the same time as the engine cranking starts and the electromagnet is energized with the passage of time as shown in the characteristic diagram of FIG. 3 (b). The valve opening gradually increases as the amount increases and passes through the slow open valve 15 which is fully opened, and is supplied to the auxiliary combustion chamber 20 provided in each cylinder head 10 through the branch pipe 12.

Therefore, the lean air-fuel ratio mixture flowing from the main combustion chamber 23 into the auxiliary combustion chamber 20 through the nozzle 22 of the mouthpiece 21 of the auxiliary combustion chamber and the auxiliary combustion chamber via the slow open valve 15. When the gas supplied to 20 is further mixed in the sub-combustion chamber 20, the air-fuel ratio in the sub-combustion chamber 20, which has the largest influence on the starting performance, changes as shown by transition (a) in FIG. 4. Therefore, by operating the slow open valve 15 at the time of starting the engine, the air-fuel ratio of the air-fuel mixture in the auxiliary combustion chamber is always kept within the combustible range for a certain period of time, so that a reliable start is made under any conditions. Is possible.

(Second Embodiment) FIG. 5 is an explanatory view of the structure of a fuel supply path of a six-cylinder gas engine according to a second embodiment of the first invention. Although the basic configuration is the same as that of the first embodiment, an electronically controlled slow open valve 15a is provided in the middle of the fuel supply path 13 to the auxiliary combustion chamber, and a signal of the engine operating condition at the time of starting is provided. A valve opening electronic control unit 17 which inputs and outputs a valve opening setting signal to the slow open valve 15a is incorporated.

The engine speed, the pressure in the intake manifold and the temperature in the intake manifold are detected as electric signals by the conversion element as signals of the operating condition at the time of engine start, and the valve opening degree electronic control unit 1
Enter 7 The control device compares and determines the detection signal from each conversion element and the feedback signal of the valve opening degree from the slow open valve 15a, and opens the valve widely compared to the first embodiment at the initial stage of cranking. If it is determined that the engine has started reliably, a valve opening setting signal is output to the slow open valve 15a so as to throttle the valve opening. When the control is performed such that a rich air-fuel mixture is formed in the auxiliary combustion chamber 20 at the initial stage of cranking as shown in the transition (b) of FIG. 6 by such an action, the starting performance can be further improved.

(Third Embodiment) FIG. 7 is a structural explanatory view of a fuel supply path of a six-cylinder gas engine according to a third embodiment of the second invention. The same members as those in FIG. 5 are designated by the same reference numerals. The description is omitted. A bypass pipe 26 bypasses the air-fuel ratio control device 4 and supplies the gas to the inlet of the turbocharger 5.

Reference numeral 27 denotes a main chamber slow open valve (structurally the same as in FIG. 3 (a)), which opens simultaneously with the start of the engine start operation and increases the valve opening with the lapse of time, thereby operating the engine. Has reached a predetermined state, for example, when the number of revolutions of 500 revolutions or more continues for 5 seconds or more, the valve opening degree electronic control unit 17 controls the valve opening so as to start the valve closing.

Reference numeral 16 is an auxiliary chamber slow open valve having the same construction as that of 15a in FIG. 5, but the valve opening timing is not the same as the start of the engine starting operation, but the main chamber slow open valve 27 has started closing. The valve opening electronic control unit 17 controls the valve opening so that the valve opening will be started later and the valve opening will be increased with time.

Next, operations and effects different from those of the second embodiment according to the first invention will be described. When the temperature of outside air, engine cooling water, lubricating oil, etc. changes, the air-fuel ratio supplied to the combustion chamber of the engine also changes. In both the present embodiment and the second embodiment, the lean air-fuel mixture generated by the air-fuel ratio control device 4 and the gas supplied through the fuel supply path 13 (when the sub chamber slow open valve 16 is fully opened) are sub-combusted. Since the air-fuel ratio is mixed in the chamber 20 to achieve the stoichiometric air-fuel ratio, if the sub chamber slow-open valve 16 is fully opened when the temperature change of the environment as described above occurs, As shown in c), it may happen that the combustible air-fuel ratio range is not reached.

In the case of the second embodiment, the auxiliary combustion chamber 20
Since gas is being supplied to the engine, when the engine starts and the number of revolutions increases, the pressure of the lean air-fuel mixture supplied to the main combustion chamber 23 by the turbocharger 5 begins to increase, so It becomes difficult for the gas to flow into the auxiliary combustion chamber 20 and the engine speed does not increase, making it difficult to obtain stable combustion.

Therefore, the gas flowing out from the bypass pipe 26 is mixed with the lean mixture generated by the air-fuel ratio control device 4, and is supplied to the main combustion chamber 23 via the turbocharger 5 and the main chamber is thrown. The open valve 27 is gradually opened to gradually increase the supply amount of the gas (the sub chamber slow open valve 16 can supply a larger amount of gas than the amount supplied when the valve is opened), and a predetermined amount is supplied. If a stable combustion state is obtained, the main chamber slow open valve 27 is gradually closed this time, and at the same time the sub chamber slow open valve 16 is gradually opened, and finally the main chamber slow open valve 27 is opened.
Is closed and the sub-chamber slow open valve 16 is fully opened to set the mixing ratio of the gas and the air supplied to the sub-combustion chamber 20 to the stoichiometric air-fuel ratio.

As described above, when the engine is started, the main chamber slow open valve 27 and the auxiliary chamber slow open valve 1
By organically operating the valve 6 under the control of the valve opening electronic control unit 17, the engine can be reliably started regardless of the ambient temperature of the outside air, engine cooling water, lubricating oil, or the like.

[0024]

According to the present invention, when the gas engine is started, the air-fuel ratio of the air-fuel mixture in the auxiliary combustion chamber, which has the greatest influence on the starting performance, can be maintained within a combustible range for a certain period of time. Therefore, good starting performance can be obtained without being affected by the type of gas used as fuel and changes in ambient temperature conditions.

[Brief description of the drawings]

FIG. 1 is a structural explanatory view of a fuel supply path of a gas engine according to a first embodiment of the first invention.

FIG. 2 is an explanatory diagram of a configuration around a combustion chamber of a gas engine having a sub combustion chamber.

FIG. 3 is a structural conceptual diagram (a) and a characteristic diagram (b) of the slow open valve according to the first embodiment of the first invention.

FIG. 4 is an explanatory view of the time variation of the air-fuel ratio in the auxiliary combustion chamber according to the first embodiment of the first invention.

FIG. 5 is a structural explanatory view of a fuel supply path of a gas engine according to a second embodiment of the first invention.

FIG. 6 is an explanatory view of the time variation of the air-fuel ratio in the auxiliary combustion chamber according to the second embodiment of the first invention.

FIG. 7 is a structural explanatory view of a fuel supply path of a gas engine according to a third embodiment of the second invention.

FIG. 8 is a structural explanatory view of a fuel supply path of a conventional gas engine.

FIG. 9 is a characteristic diagram of an on-off valve that supplies gas to a sub-combustion chamber of a conventional gas engine.

FIG. 10 is an explanatory diagram of a time variation of the air-fuel ratio in the auxiliary combustion chamber of the conventional gas engine.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fuel supply path (main combustion chamber), 2 ... On-off valve, 3 ... Air cleaner, 4 ... Air-fuel ratio control device, 5 ... Exhaust turbocharger, 8 ... Mixture cooler, 9 ... Air supply manifold, 10 ... Cylinder head, 12 ... Gas branch pipe, 13 ... Fuel supply path (sub combustion chamber), 14 ... Open / close valve, 15, 15a ... Slow open valve, 16 ... Sub chamber slow open valve (electronic control), 17 ... Valve opening degree Electronic control device, 20 ... Secondary combustion chamber,
21 ... Subcombustion base, 22 ... Base injection port, 23 ... Main combustion chamber, 24 ... Piston, 25 ... Spark plug, 26 ... Bypass pipe, 27 ... Main chamber slow open valve (electronic control).

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location F02D 41/02 301 F02D 41/02 301K 41/06 330 41/06 330S

Claims (2)

[Claims] 1. A fuel supply path (1) for guiding a lean mixture of air and gas generated by an air-fuel ratio control device (4) to a main combustion chamber (23) via an exhaust turbocharger (5). When,
In a gas engine having a fuel supply path (13) for guiding gas to a sub-combustion chamber (20), the fuel supply path (13) leading to the sub-combustion chamber is opened simultaneously with the start of the engine start operation and the passage of time. At the same time, a slow-open valve (15) that increases the valve opening degree to fully open is provided, and a fuel supply device for starting a gas engine. 2. A fuel supply path (1) for guiding a lean mixture of air and gas produced by an air-fuel ratio control device (4) to a main combustion chamber (23) via an exhaust turbocharger (5). When,
In a gas engine having a fuel supply path (13) for guiding gas to a sub combustion chamber (20), an air-fuel ratio control device (4) and a turbocharger (5) for a fuel supply path (1) leading to the main combustion chamber. By-pass pipe (2) to bypass the gas between
6) is provided, and the valve opening is started in the bypass pipe (26) at the same time when the engine starting operation is started, and the valve opening is increased with the lapse of time so that the valve closing is started when the operating state of the engine reaches a predetermined state. A main chamber slow open valve (27) that leads to the closing of the valve is provided, and the main chamber slow open valve (2) is provided in a fuel supply path (13) leading to the auxiliary combustion chamber.
7) After opening the valve, start opening the valve and increase the valve opening over time to fully open the sub chamber slow open valve (16), and further input the signal of the engine operating condition to both slow open valves. A fuel supply device for starting a gas engine, comprising a valve opening electronic control device (17) for outputting a valve opening setting signal to (16, 27).