JP5072765B2 - Spark ignition gas fuel internal combustion engine - Google Patents

Description

  The present invention relates to a spark ignition gas fuel internal combustion engine using hydrogen, CNG, propane, butane or the like as fuel.

In this type of gas fuel internal combustion engine, output control is performed by adjusting the intake air amount by a throttle valve and the fuel supply amount by a gas fuel supply valve. In this type of internal combustion engine, in order to generate a lateral vortex or vertical vortex intake vortex flow in a cylinder, a bypass passage may be provided in the intake passage so as to bypass the throttle valve (for example, Patent Document 1). reference).
Japanese Patent No. 3557314

  By the way, in the conventional internal combustion engine, in the partial load operation region where the throttle valve is substantially fully closed, a negative pressure is maintained in the intake passage, so that there is a problem that a pumping loss occurs.

  The present invention has been made in view of the above-described conventional situation, and provides a spark ignition gas fuel internal combustion engine that can improve pumping loss by reducing the negative pressure of the intake passage in the partial load operation region. It is an issue.

  According to the first aspect of the present invention, an intake passage that communicates with the combustion chamber, an intake valve that opens and closes an intake opening that opens into the combustion chamber of the intake passage, and a passage area that is disposed in the intake passage and that depends on the engine operating state. An intake control valve for changing the intake passage, a throttle valve disposed upstream of the intake control valve in the intake passage, and an intake vortex in the combustion chamber so as to bypass the intake control valve. A spark ignition type gas fuel internal combustion engine provided with a bypass passage and a check valve that is interposed in the bypass passage and allows only the flow of intake air to the cylinder side, the intake control valve of the intake passage A gas fuel supply valve for supplying gas fuel is disposed downstream, and at least under the operating conditions in which the intake control valve is substantially fully closed, the gas fuel is supplied before the start of the intake stroke or the first half of the intake stroke. Featuring There.

  The invention of claim 2 is a spark ignition type gas fuel internal combustion engine similar to that of claim 1, wherein a gas fuel supply valve for supplying gas fuel downstream from the check valve of the bypass passage is arranged. The gas fuel is supplied before the start of the intake stroke or in the first half of the intake stroke at least under an operating condition where the intake control valve is substantially fully closed.

  Here, in the present invention, supplying gas fuel before the start of the intake stroke does not necessarily require supplying all of the required fuel amount, but also includes supplying a part thereof.

  In the present invention, the first half of the intake stroke means a period from the start of the intake stroke until the lift amount of the intake valve reaches the maximum lift.

  According to a third aspect of the present invention, in the spark ignition gas fuel internal combustion engine according to the first or second aspect, a surge tank is connected between the intake control valve and the throttle valve of the intake passage, and the intake control valve is In the intake passage, it is provided in the vicinity of the connection portion of the surge tank.

  According to a fourth aspect of the present invention, in the spark ignition type gas fuel internal combustion engine according to the first or second aspect, the supply of the gas fuel is terminated before the intake stroke is started at least in a low load operation region.

  According to the internal combustion engine of the first aspect of the present invention, the gas fuel is supplied to the intake passage before the start of the intake stroke or the first half of the intake stroke at least under an operating condition in which the intake control valve is substantially fully closed. Yes. When gas fuel is supplied to the intake passage before the intake stroke starts, it is effective in the extremely low load operation region. That is, in the extremely low load operation region, the intake passage is maintained in a negative pressure state because the intake control valve is fully closed and the check valve is provided in the bypass passage. By supplying gas fuel having a volume larger than that of liquid fuel to the intake passage in the negative pressure state, the negative pressure in the intake passage is reduced, and the pumping loss can be improved. For example, when LPG fuel that is gasified at room temperature in a very short time is supplied, the negative pressure upstream of the intake valve in the intake passage is immediately reduced, and the pumping loss can be improved. Further, the internal EGR is reduced by supplying the fuel gas before the start of the intake stroke, whereby the combustion state in the extremely low load operation region is improved.

  When gas fuel is supplied to the intake passage in the first half of the intake stroke, it is effective in the medium and high load operation range. That is, in this case, since the intake passage has a large negative pressure at the beginning of opening of the intake valve, the internal EGR amount can be maintained, and further, by supplying gas fuel in the first half of the intake stroke, the total mixture amount (new air + gas Fuel + internal EGR) increases, the negative pressure in the intake passage decreases, and the pumping loss decreases. Furthermore, a fuel consumption reduction effect can be expected due to a substantial increase in compression pressure due to internal EGR.

  According to the invention of claim 2, the gas fuel is supplied to the bypass passage before the start of the intake stroke or the first half of the intake stroke at least under an operating condition in which the intake control valve is substantially fully closed. When gas fuel is supplied to the bypass passage before the start of the intake stroke, it is effective in the extremely low load operation region as in the case of claim 1, and the negative pressure state of the intake passage can be reduced, and the pumping loss is reduced. By improving and reducing the internal EGR, the combustion state in the extremely low load operation region is improved.

  When gas fuel is supplied to the bypass passage in the first half of the intake stroke, it is effective in the middle and high load operation areas. That is, in this case, the same effect as in the case of claim 1 can be obtained, and further, a strong intake vortex flow such as a vertical vortex and a horizontal vortex is formed by jetting gas fuel into the bypass passage during the intake stroke. Rapid combustion is possible. In addition, when combustion is slow, a so-called backfire is generated that burns in the intake passage at the time of overlap. In the present invention, the backfire can be suppressed by the effect of the rapid combustion.

  The internal EGR has an effect of substantially increasing the compression pressure in the partial load operation region, and is effective in improving the thermal efficiency, but the flame propagation speed is reduced in the theoretical air-fuel ratio (λ = 1) operation. However, it is difficult to obtain a sufficient thermal efficiency effect. In the present invention, in the partial load operation region, the flow from the bypass passage forms an intake vortex having a strong lateral vortex or vertical vortex in the cylinder. Therefore, mixing of gas fuel, fresh air, burned gas, and intake vortex As a result, rapid combustion is possible, and high efficiency combustion, low pollution exhaust gas, and low pumping loss are obtained.

  In the invention of claim 3, since the intake control valve is disposed in the vicinity of the connection portion of the surge tank of the intake passage, the passage volume from the intake control valve to the intake valve of the intake passage can be increased, and in the first half of the intake stroke The amount of air required to be sucked into the cylinder can be stored. As a result, while reducing the pumping loss in the first half of the intake stroke, a strong intake vortex can be ejected in the second half of the intake stroke, and fuel efficiency can be improved.

  According to the fourth aspect of the present invention, the supply of gas fuel is finished before the start of the intake stroke at least in the low load operation region, so that excessive internal EGR can be suppressed while reducing the negative pressure in the intake passage. That is, in low load operation including idling, the intake air pressure is small because the intake air amount is small, and the inflow rate of the internal EGR is increased accordingly. For this reason, flame propagation becomes unstable and misfire is likely to occur. In the present invention, since the supply of gas fuel is terminated before the start of the intake stroke, the amount of gas fuel is increased accordingly, the intake negative pressure is reduced, and as a result, the inflow rate of the internal EGR can be reduced and stable. Combustion is possible and misfire can be prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  1 and 2 are views for explaining a spark ignition type gas fuel internal combustion engine according to a first embodiment of the present invention. FIG. 1 is a schematic configuration diagram of the spark ignition type internal combustion engine, and FIG. It is sectional drawing.

  In the figure, reference numeral 1 denotes a four-cycle multi-cylinder spark ignition gas fuel internal combustion engine. The internal combustion engine 1 has a cylinder block 2 in which a plurality of cylinder bores (cylinders) 2a, 2a are connected to a cylinder head 3 in which a combustion recess 3a is formed so as to face each cylinder bore 2a. The piston 4 has a schematic structure in which it is slidably inserted.

  A combustion chamber 5 is formed by a space surrounded by the cylinder bore 2 a, the combustion recess 3 a and the top surface of the piston 4. The piston 4 is connected to the crankshaft 11 by a connecting rod 4a.

  In the combustion recess 3a of the cylinder head 3, two intake openings 3b and 3b communicating with the combustion chamber 5 and two exhaust openings 3c and 3c are formed. The intake openings 3b and the exhaust openings 3c are disposed on one side and the other side of the crankshaft axis c, and are substantially opposed to each other with the axis c interposed therebetween.

  The intake opening 3b and the exhaust opening 3c are respectively provided with an intake valve 6 and an exhaust valve 7, and the intake valve 6 and the exhaust valve 7 are opened and closed by an intake cam shaft 8 and an exhaust cam shaft 9, respectively. Although not shown, the engine 1 of this embodiment includes a variable valve mechanism that can adjust an overlap period in which the intake valve 6 and the exhaust valve 7 are simultaneously opened.

  A spark plug 10 is mounted on the cylinder bore 2a of the cylinder head 3 so as to face the center of the combustion recess 3a. The spark plug 10 is disposed slightly displaced from the axis c toward the exhaust valve 7 side.

  Each intake opening 3b is led out to one side wall of the cylinder head 3 by intake ports 3d and 3d, and each exhaust opening 3c is led out to the other side wall of the cylinder head 3 by exhaust ports 3e and 3e.

  An exhaust pipe 12 is connected to each exhaust port 3e, a catalyst 14 is connected to the merging portion 13 of the exhaust pipe 12, and a muffler (not shown) is connected to the downstream end of the merging portion.

  Intake pipes (intake passages) 15 and 15 communicating with the intake opening 3b are connected to the intake ports 3d.

  A common surge tank 16 is connected to the upstream end portions 15b, 15b of each intake pipe 15, and an air cleaner (not shown) is connected to the surge tank 16 with an intake merging pipe 17 interposed therebetween. Yes. The intake merging pipe 17 is provided with a throttle valve 18 common to each cylinder.

  At the upstream end portion 15b of each intake pipe 15, intake control valves 23, 23 for changing the passage area according to the operating state of the internal combustion engine 1 are disposed. The intake control valve 23 is disposed in the vicinity of the surge tank 16 connection portion of the intake pipe 15.

  The internal combustion engine 1 includes bypass passages 25, 25 arranged to bypass the intake control valve 23, and a check valve 26 provided on the upstream side of each bypass passage 25.

  Each bypass passage 25 directs and ejects air so that a horizontal or vertical vortex intake flow is generated in the cylinder bore 2a, and is arranged below the intake pipe 15 along the same. ing.

  A downstream portion of each bypass passage 25 is branched into two branch pipes 25a and 25a, and a downstream end port 25a 'of each branch pipe 25a is connected to the vicinity of the intake opening 3b of the intake port 3d. That is, the bypass passage 25 communicates with the intake pipe 15 via the downstream end port 25a ′. The upstream end 25 b of the bypass passage 25 is connected to the surge tank 16.

  The check valve 26 is of a reed valve type that allows only a flow of intake air to the cylinder side and prevents a reverse flow, and is disposed in the vicinity of the upstream end 25 b of the bypass passage 25.

Downstream of the intake control valve 23 of each intake pipe 15, specifically, the intake port 3d.
An electromagnetic valve type gas fuel supply valve 20, 20 is mounted in the vicinity of the upstream end. Each gas fuel supply valve 20 is arranged to inject gas fuel such as hydrogen, propane, butane, etc. toward the center of the back of the intake valve 6.

  The internal combustion engine 1 includes an ECU 32 that controls the opening and closing of the intake control valve 23 and the fuel injection timing and the injection amount of the gas fuel supply valve 20 according to the engine operating state.

  The ECU 32 fully closes the intake control valve 23 and supplies gas fuel to the downstream side of the intake control valve 23 of the intake pipe 15 before the start of the intake stroke in the low and medium load partial load operation regions. In addition, the gas fuel supply is terminated before the intake valve 6 is opened (before the intake stroke starts). Gas fuel may be supplied in the first half of the intake stroke, that is, from when the intake valve starts to open until the maximum lift is reached, or gas fuel is supplied from the start of the intake stroke to the first half of the intake stroke. You may do it.

  According to the internal combustion engine 1 of the present embodiment, gas fuel is supplied to the intake pipe 15 and before the start of the intake stroke in the partial load operation region where the intake control valve 23 is substantially fully closed. The negative pressure state of 15 is reduced by the gas fuel, and the pumping loss can be improved. That is, in the partial load operation region, the intake control valve 23 is substantially fully closed and the check valve 26 is provided in the bypass passage 25, so that the intake pipe 15 is maintained in a negative pressure state. Yes. By supplying gas fuel having a volume larger than that of liquid fuel such as gasoline into the intake pipe 15 in the negative pressure state, the negative pressure in the intake pipe 15 is reduced. For example, when LPG fuel that is gasified at room temperature in a very short time is supplied, the negative pressure upstream of the intake valve 6 in the intake pipe 15 is immediately reduced, and the pumping loss can be further improved.

  In this embodiment, since the intake control valve 23 is disposed in the vicinity of the surge tank 16 connection portion of the intake pipe 15, the passage volume from the intake control valve 23 to the intake valve 6 of the intake pipe 15 can be increased, and the intake air In the first half of the stroke, the amount of air necessary for suction into the cylinder bore 2a can be stored. As a result, while reducing the pumping loss in the first half of the intake stroke, a strong intake vortex can be ejected in the second half of the intake stroke, and fuel efficiency can be improved.

  In this embodiment, since the gas fuel supply valve 20 is disposed downstream of the intake control valve 23 of the intake pipe 15, mixing is promoted by premixing and turbulent flow due to high-speed flow when passing through the clearance of the intake valve. Thus, the mixing in the cylinder bore 2a can be performed satisfactorily.

  In the present embodiment, since the supply of gas fuel is terminated before the intake valve 6 is opened in the low load operation region, the negative pressure of the intake pipe 15 can be reduced, and excessive internal EGR can be suppressed. That is, in low load operation including idling, the intake air pressure is small because the intake air amount is small, and the inflow rate of the internal EGR is increased accordingly. For this reason, flame propagation becomes unstable and misfire is likely to occur. Such a phenomenon becomes more prominent as the overlap period is wider.

  In this embodiment, since the supply of gas fuel is terminated before the intake valve 6 is opened, the intake negative pressure is reduced, the inflow rate of the internal EGR at the time of overlap can be reduced, and stable combustion is possible. And misfire can be prevented.

  In the above embodiment, the gas fuel is injected and supplied before the start of the intake stroke in the partial load operation region. However, in the present invention, the gas fuel may be supplied after the overlap of the intake stroke. .

  As described above, in the partial load operation region, when the gas fuel is supplied after the overlap is completed, the gas fuel is supplied after the exhaust valve 7 is closed, so that the inside introduced before the exhaust valve 7 is closed. The negative pressure state of the intake passage can be reduced without reducing EGR, and the pumping loss can be improved.

  Further, since the gas fuel is supplied after the overlap is completed, rapid combustion is possible and backfire can be suppressed.

  In the internal combustion engine 1, by providing an overlap period in which the intake valve 6 and the exhaust valve 7 open simultaneously, an appropriate amount of internal EGR flows into the intake passage, thereby reducing pumping loss and improving fuel efficiency. it can.

  In the present embodiment, the intake negative pressure is reduced by the internal EGR flowing into the intake pipe 15 from the cylinder bore 2a during the overlap, and the intake negative pressure is reduced without reducing the internal EGR by supplying gas fuel after the overlap is completed. The pumping loss can be further improved.

  The internal EGR has the effect of substantially increasing the compression pressure in the partial load operation region, and is effective in improving the thermal efficiency, but the flame propagation speed is reduced in the theoretical air-fuel ratio (λ = 1) operation. It is difficult to obtain a sufficient thermal efficiency effect.

  In this embodiment, at the time of partial load, since the intake flow having a strong horizontal vortex or vertical vortex flows from the bypass passage 25 into the cylinder bore 2a, rapid combustion is performed by mixing and turbulence of gas fuel, fresh air, and burned gas. It is possible to achieve high efficiency combustion, low pollution exhaust gas, and low pumping loss.

  FIG. 3 is a view for explaining a gas fuel internal combustion engine according to a second embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts.

  The gas fuel internal combustion engine 1 of the present embodiment connects the gas fuel supply valve 20 downstream of the check valve 26 in the bypass passage 25, and in the first half of the intake stroke, specifically, the maximum lift after the intake valve 6 starts to open. It is configured to supply gas fuel during the open period until it becomes.

  In the present embodiment, since gas fuel is supplied to the bypass passage 25 in the first half of the intake stroke, a strong intake vortex flow is generated in the cylinder bore 2a by fresh air and gas fuel (see the arrow in FIG. 2). ). Thereby, good combustion is obtained. As a result, even when gas fuel having a smaller penetration force than liquid fuel is supplied, mixing of burned gas, fresh air, and gas fuel in the cylinder bore 2a can be promoted, and fuel efficiency can be improved.

  The gas fuel may be supplied to the bypass passage 25 before the start of the intake stroke. In this case, the gas fuel is filled into the intake passage 15 via the bypass passage 25, and the pumping loss can be reduced. Moreover, since the intake negative pressure before overlap can be reduced, the internal EGR at the time of overlap can be reduced, and combustion in an extremely low load operation region can be improved.

1 is a schematic configuration diagram of a spark ignition type gas fuel internal combustion engine according to a first embodiment of the present invention. It is sectional drawing of the said internal combustion engine. It is a schematic block diagram of the spark ignition type gas fuel internal combustion engine by 2nd Embodiment of this invention.

Explanation of symbols

1 Internal combustion engine 3b Intake opening 5 Combustion chamber 6 Intake valve 7 Exhaust valve 12 Exhaust pipe (exhaust passage)
15 Intake pipe (intake passage)
16 Surge tank 18 Throttle valve 20 Gas fuel supply valve 23 Intake control valve 25 Bypass passage 26 Check valve

Claims (4)

An intake passage communicating with the combustion chamber;
An intake valve that opens and closes an intake opening that opens into the combustion chamber of the intake passage;
An intake control valve that is disposed in the intake passage and changes a passage area according to an engine operating state;
A throttle valve disposed upstream of the intake control valve in the intake passage;
A bypass passage provided to bypass the intake control valve and to generate an intake vortex in the combustion chamber;
A spark ignition gas fuel internal combustion engine provided with a check valve interposed in the bypass passage and allowing only a flow of intake air to the cylinder side;
A gas fuel supply valve for supplying gas fuel downstream of the intake control valve of the intake passage is disposed;
A spark ignition type gas fuel internal combustion engine which supplies gas fuel before the start of the intake stroke or the first half of the intake stroke at least under an operating condition in which the intake control valve is substantially fully closed. An intake passage communicating with the combustion chamber;
An intake valve that opens and closes an intake opening that opens into the combustion chamber of the intake passage;
An intake control valve that is disposed in the intake passage and changes a passage area according to an engine operating state;
A throttle valve disposed upstream of the intake control valve in the intake passage;
A bypass passage provided to bypass the intake control valve and to generate an intake vortex in the combustion chamber;
A spark ignition gas fuel internal combustion engine provided with a check valve interposed in the bypass passage and allowing only a flow of intake air to the cylinder side;
A gas fuel supply valve for supplying gas fuel downstream from the check valve of the bypass passage is disposed;
A spark ignition type gas fuel internal combustion engine which supplies gas fuel before the start of the intake stroke or the first half of the intake stroke at least under an operating condition in which the intake control valve is substantially fully closed. The spark ignition type gas fuel internal combustion engine according to claim 1 or 2,
A surge tank is connected between the intake control valve and the throttle valve in the intake passage,
The spark ignition type gas fuel internal combustion engine, wherein the intake control valve is provided in the vicinity of a connection portion of the surge tank in the intake passage. The spark ignition type gas fuel internal combustion engine according to claim 1 or 2,
At least in the low load operation region, the spark fuel gas fuel internal combustion engine is characterized in that the supply of gas fuel is terminated before the intake stroke starts.

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