JP2008031922A - Internal combustion engine with fuel reforming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily supply necessary and sufficient reformed gas into a cylinder from an early stage of cranking in start of an internal combustion engine. <P>SOLUTION: An engine 10 provided with a fuel reforming device 22 is provided with a suction passage 11 connected to a suction port 13 and including a throttle valve 21, a reformed gas supply passage 26 branching off of the suction passage 11 and supplying reformed gas from the fuel reforming device 22 to a reformed gas supply part, and a vacuum generation valve 30 arranged at a section in an upstream side near the reformed gas supply part of the reformed gas supply passage 26 in the suction passage 11 in a downstream side of the throttle valve 21 and generating vacuum to secure sufficient supply quantity of reformed gas to the suction port 13 by being closed at start of the engine 10. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an internal combustion engine with a fuel reformer that generates power by burning a mixture of reformed gas and air generated by the fuel reformer in a combustion chamber. The present invention relates to an internal combustion engine with a fuel reformer that can easily supply necessary and sufficient reformed gas into the cylinder from the beginning of cranking.

  Conventionally, a fuel reformer that supplies hydrocarbon fuel and heated air to a reforming catalyst and reacts them to extract gases such as carbon monoxide and hydrogen, and a reformed gas generated by the fuel reformer There is known an internal combustion engine that generates power by burning an air-fuel mixture in a combustion chamber.

  As such an internal combustion engine with a fuel reformer, one having an intake passage including a throttle valve and a reformed air supply passage branched from the intake passage on the upstream side of the throttle valve is known (for example, Patent Document 1). The fuel reformer is supplied with air via a reformed air supply path.

  Generally, when the internal combustion engine is started, the amount of air sucked into the combustion chamber per unit time is small. For this reason, even if the fuel reforming device is started to operate the internal combustion engine, in the conventional internal combustion engine, the reformed air supply path branched from the intake path upstream of the throttle valve is used. As a result, air could not be sufficiently supplied to the fuel reformer.

  In order to supply sufficient air to the fuel reformer when the internal combustion engine is started, the following technique has been proposed (see, for example, Patent Document 2). That is, in an internal combustion engine with a fuel reformer, it is connected to a combustion chamber, and is branched from the intake passage including the throttle valve and the intake passage upstream of the throttle valve, and is connected to the fuel reformer. A reforming air supply path and control means for starting fuel reforming in the fuel reforming apparatus after the throttle valve opening of the intake path is set to a minimum.

  As an associated known technique, in an internal combustion engine in which an intake flow control valve is disposed in the intake passage and the intake flow control valve is controlled to be closed when the engine is started, an intake air amount at the time of engine start is obtained, An intake air control device having intake air flow control valve opening degree control means for controlling the opening degree of the intake air flow control valve so that the intake air amount becomes a predetermined target air amount at the time of engine start based on the intake air amount Has also been proposed (see, for example, Patent Document 3).

Japanese Patent Laid-Open No. 9-21362 JP 2005-83208 A JP-A-9-14017

  When starting the internal combustion engine with the reformed gas, it is necessary to supply an appropriate mixture of reformed gas and air into the cylinder from the beginning of cranking. However, in the above-described prior art, the negative pressure in the intake port is insufficient during cranking at the time of engine start, particularly during several cycles at start-up, so that the reformed gas is sufficiently supplied into the cylinder. There was a possibility that it could not be done. For this reason, there is a possibility that the supply amount of the reformed gas will be insufficient, exhausted without being combusted in the cylinder, and hydrocarbon emissions will deteriorate.

  In addition, as in the prior art disclosed in Patent Document 2, it is possible to increase the negative pressure of the intake port and intake manifold by closing the throttle valve. However, since the volume of the surge tank is large, sufficient negative pressure is ensured. Is not always easy.

  Further, depending on how the throttle valve is closed, there is a possibility that the air to be supplied to the internal combustion engine is insufficient, and combustion in the internal combustion engine cannot be maintained.

  The present invention has been made in view of the above, and provides an internal combustion engine with a fuel reformer that can easily supply necessary and sufficient reformed gas into the cylinder from the beginning of cranking when the internal combustion engine is started. The purpose is to do.

  In order to solve the above-described problems and achieve the object, an internal combustion engine with a fuel reforming apparatus according to claim 1 of the present invention is a modified engine containing a predetermined fuel component by reforming a mixture of fuel and air. An internal combustion engine with a fuel reformer that includes a fuel reformer that generates a quality gas and generates power by burning a mixture of the reformed gas and air in a combustion chamber. An intake passage including a reformed gas supply passage that is branched from the intake passage upstream of the throttle valve and supplies the reformed gas from the fuel reformer to the intake passage by a reformed gas supply unit; The reformer is disposed inside the intake passage on the downstream side of the throttle valve and upstream or near the upstream side of the reformed gas supply unit, and is closed when the internal combustion engine is started. Gas supply unit It is characterized in that it comprises an intake flow control valve for adjusting the supply amount or supply direction of the reformed gas supplied to et the intake port, the.

  Therefore, according to the present invention, by closing the intake flow control valve when starting the internal combustion engine, the volume of the intake passage from the intake valve to the intake flow control valve is reduced, and the intake flow control valve is disposed. The cross-sectional area of the intake passage at the position is narrowed.

  For this reason, the air flow velocity is increased downstream of the intake flow control valve, and a stronger negative pressure is generated than when the intake flow control valve is opened. It is sucked by the negative pressure and easily introduced into the intake port together with air.

  In addition, when an air pump that pumps air is provided upstream of the reformed gas supply passage, the reformed gas pumped by the air pump is closed by closing the intake flow control valve when the internal combustion engine is started. For example, backflow to the surge tank side disposed upstream of the intake flow control valve is suppressed, and flow into other cylinders is suppressed.

  An internal combustion engine with a fuel reformer according to a second aspect of the present invention is the valve according to the first aspect, wherein the intake flow control valve is formed by notching the reformed gas supply unit. An opening is provided.

  Therefore, according to the present invention, the air flow velocity is further increased at the valve opening of the intake air flow control valve, and a stronger negative pressure is generated in the vicinity of the reformed gas supply unit. And is easily introduced into the intake port.

  According to a third aspect of the present invention, in the internal combustion engine with a fuel reformer according to the first or second aspect, the reformed gas supply passage is connected to each intake port, and the reformed gas supply A reformed gas flow rate control valve for adjusting the flow rate of the reformed gas is provided in the middle of the passage.

  Therefore, according to the present invention, necessary and sufficient reformed gas is accurately supplied into each cylinder by adjusting the flow rate of the reformed gas flow rate control valve in the reformed gas supply passage connected to each intake port.

  According to the internal combustion engine with a fuel reformer according to the present invention (Claim 1), since the negative pressure is generated by closing the intake flow control valve and the reformed gas is strongly sucked, it is necessary from the beginning of cranking. Sufficient reformed gas can be easily supplied into the cylinder.

  Further, when an air pump that pumps air is provided in the upstream portion of the reformed gas supply passage, the pressure prevents the reformed gas from flowing back to the intake passage upstream of the intake flow control valve. it can. Therefore, it is possible to suppress misfiring due to an insufficient amount of the reformed gas to be supplied into the cylinder and deterioration of emission. Furthermore, it is possible to suppress the deterioration of emissions caused by the reformed gas flowing into the other cylinders.

  Further, according to the internal combustion engine with a fuel reformer according to the present invention (Claim 2), the air flow velocity is further increased at the valve opening of the intake flow control valve, and is stronger in the vicinity of the reformed gas supply unit. Since the negative pressure is generated, the reformed gas can be sucked more strongly and a necessary amount can be introduced into the intake port.

  Further, according to the internal combustion engine with a fuel reformer according to the present invention (Claim 3), the necessary and sufficient modification is achieved by adjusting the flow rate of the reformed gas flow rate control valve of the reformed gas supply passage connected to each intake port. The quality gas can be accurately supplied into each cylinder.

  Embodiments of an internal combustion engine with a fuel reformer (hereinafter referred to as an engine as appropriate) according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

  1 is a schematic configuration diagram showing an internal combustion engine with a fuel reformer according to Embodiment 1 of the present invention, FIG. 2 is a flowchart showing a control method, and FIG. 3 is a side sectional view showing the vicinity of a reformed gas supply unit. FIG. 4 is a front view showing a negative pressure generating valve in the intake passage.

  As shown in FIG. 1, the engine 10 is a port injection type four-cycle gasoline engine configured by a known technique, and includes a fuel reformer 22 described later. That is, an intake valve 15 is disposed at the intake port 13 facing the combustion chamber 10a, and an exhaust valve 16 is disposed at the exhaust port 14 facing the combustion chamber 10a.

  An air flow meter 20 and a throttle valve 21 are provided in the intake passage 11, and a surge tank 19 is provided on the downstream side of the throttle valve 21. The intake passage 11 downstream of the surge tank 19 is connected to the intake port 13.

  The fuel injected into the intake port 13 by the injector 17 is introduced into the combustion chamber 10 a from the intake port 13 by opening the intake valve 15 together with the air introduced from the intake passage 11. Sparks are ignited.

  The fuel reformer 22 is a well-known device that supplies hydrocarbon fuel and air to a heated reforming catalyst and reacts them to take out reformed gases such as carbon monoxide and hydrogen. The reformed gas supply passage 26 is branched from the intake passage 11 on the upstream side.

  Although not shown, the injector 24 of the fuel reformer 22 is connected to a fuel tank via a fuel pump, and is configured to be able to inject hydrocarbon-based fuel such as gasoline toward the fuel reforming catalyst 23. ing. The valve 25 provided in the reformed gas supply passage 26 is for supplying or blocking the reformed gas to the intake port 13.

  Further, as shown in FIG. 3, the downstream end portion of the reformed gas supply passage 26 communicates with the intake passage 11 downstream of the surge tank 19 as the reformed gas supply portion 26a. The reformed gas supply unit 26a is positioned downstream of a negative pressure generating valve 30 described later.

  Next, the negative pressure generation valve (intake flow control valve) 30 will be described with reference to FIGS. 1, 3, and 4. As shown in the figure, the negative pressure generating valve 30 is provided in the intake passage 11 downstream of the surge tank 19 so as to be opened and closed by a rotating shaft 30a.

  Further, the valve opening 30b of the negative pressure generating valve 30 is formed as a notch toward the reformed gas supply unit 26a so as to form a predetermined opening even in the closed state.

  That is, the negative pressure generating valve 30 is closed to reduce the volume of the intake passage 11 from the intake valve 15 to the negative pressure generating valve 30, and the intake passage at the position where the negative pressure generating valve 30 is disposed. 11 is provided to narrow the cross-sectional area of the channel.

  The exhaust passage 12 of the engine 10 is provided with an exhaust catalyst 27 for purifying smoke, NOx, HC and the like in the exhaust gas.

  The intake valve 15, exhaust valve 16, throttle valve 21, negative pressure generating valve 30, valve 25, spark plug 18, injectors 17 and 24, and the like are controlled by an electronic control unit (ECU) (not shown).

  A schematic operation when starting the engine 10 configured as described above will be described. First, air is introduced through the reformed gas supply passage 26, and fuel such as gasoline is injected from the injector 24 controlled by the ECU. The fuel such as gasoline is vaporized and mixed with the introduced air, and the hydrocarbon-based fuel and air react with each other by the fuel reforming catalyst 23.

  As this reaction proceeds, a reformed gas (reformed fuel) containing carbon monoxide and hydrogen as fuel components is generated. The obtained reformed gas is introduced into the intake passage 11 from the reformed gas supply passage 26 through the valve 25 by the negative pressure generated during the intake stroke, and is supplied to the intake port 13.

  In particular, when the engine 10 is started, sufficient reformed gas is supplied to the intake port 13 by the negative pressure generated by closing the negative pressure generating valve 30 as described later. Air is introduced into the intake port 13 through a throttle valve 21 whose opening is adjusted by the ECU.

  Therefore, the reformed gas introduced from the fuel reformer 22 into the intake port 13 is further mixed with air and then sucked into the combustion chamber 10a. When the spark plug 18 is ignited at a predetermined timing, carbon monoxide and hydrogen, which are fuel components, are combusted in the combustion chamber 10a to reciprocate the piston, whereby power can be obtained from the engine 10. .

  Next, the control method will be described with reference to FIGS. 1, 3 and 4 based on FIG. As shown in FIG. 2, when the engine 10 is started with the reformed gas (Yes at Step S10), the negative pressure generating valve 30 is closed (Step S20), and the engine 10 is started.

  As shown in FIG. 3 in an enlarged manner, by closing the negative pressure generating valve 30 at the time of starting, the volume of the intake passage 11 from the intake valve 15 to the negative pressure generating valve 30 is reduced, and negative pressure generation is performed. The cross-sectional area of the intake passage 11 at the position where the valve 30 is disposed becomes narrow.

  That is, as shown in FIG. 4, when the negative pressure generating valve 30 is closed, the flow path of the intake passage 11 becomes a valve opening 30b, and the flow path is narrowed compared to the case where the negative pressure generating valve 30 is open. Narrow.

  For this reason, the air flow rate is high in the vicinity of the valve opening 30b, and a negative pressure that is even stronger than that at the time of opening the negative pressure generating valve 30 is generated downstream in the vicinity thereof. Since the reformed gas supply unit 26a serving as an opening is located near the downstream of the location where the air flow rate increases, the reformed gas flowing through the reformed gas supply passage 26 is sucked by the negative pressure, and the air and The air-fuel mixture is easily introduced into the intake port 13.

  Subsequently, when the current rotational speed of the engine 10 exceeds the predetermined rotational speed N1 (Yes at Step S30), it is determined that the air-fuel mixture in the cylinder has completely exploded, and the negative pressure generating valve 30 is opened (Step S40). ), The control is terminated.

  On the other hand, the negative pressure generating valve 30 is kept closed until it is determined that the air-fuel mixture in the cylinder has completely exploded (No at Step S30, Step S20).

  After the air-fuel mixture in the cylinder has completely exploded, a large negative pressure is generated in the intake passage 11 (intake port 13), so that the reformed gas can be sufficiently supplied even when the negative pressure generation valve 30 is opened. . Further, the intake pressure loss can be reduced by opening the negative pressure generating valve 30.

  If the engine 10 is not started by the reformed gas (No at Step S10), the negative pressure generating valve 30 is opened (Step S40) because it is not subject to this control.

  As described above, according to the internal combustion engine with a fuel reformer according to the first embodiment, the necessary pressure and sufficient reformed gas can be generated from the initial stage of cranking by closing the negative pressure generating valve 30 when the engine 10 is started. It can be easily supplied into the cylinder.

  FIG. 5 is a side sectional view showing the vicinity of a reformed gas supply part of an internal combustion engine with a fuel reformer according to Embodiment 2 of the present invention. In the following description, the same or equivalent parts as those already described and step numbers are denoted by the same reference numerals, and redundant description is omitted or simplified.

  In the first embodiment, the reformed gas supply unit 26 a is positioned downstream of the negative pressure generation valve 30. However, in the second embodiment, the reformed gas supply unit 26 a is provided in the valve opening 30 b of the negative pressure generation valve 30. Is located almost directly above (near the downstream).

  That is, in the second embodiment, the reformed gas is sucked using the air flow velocity that is most increased at the valve opening 30b of the negative pressure generating valve 30. The other basic configuration and control method are the same as those in the first embodiment, and a duplicate description is omitted.

  As described above, according to the internal combustion engine with a fuel reformer according to the second embodiment, it is not necessary to position the reformed gas supply unit 26a at a location far downstream of the negative pressure generating valve 30, and freedom of mounting is reduced. The degree can be expanded.

  6 is a schematic diagram showing an internal combustion engine with a fuel reformer according to Embodiment 3 of the present invention, and FIG. 7 is an internal combustion engine with a fuel reformer provided with a reformed gas flow rate control valve corresponding to each cylinder. FIG. 8 is a schematic diagram showing the opening timing of the reformed gas flow rate control valve.

  As shown in FIGS. 6 to 7, the third embodiment has a reformed gas for controlling the flow rate of the reformed gas supplied to the intake system of the engine 10 in addition to the configuration of the first embodiment (see FIG. 1). A flow control valve 32 is provided for each cylinder of the engine 10.

  As shown in FIG. 8, when the engine 10 is started, the reformed gas flow rate control valve 32 is opened from the latter half of the exhaust stroke to the middle of the intake stroke of each cylinder. The reformed gas flow control valve 32 is also controlled to open and close by the ECU.

  Note that the valve 25 provided in the first embodiment is not required in the third embodiment because it is not necessary due to the introduction of the reformed gas flow rate control valve 32.

  During the intake stroke of each cylinder, the negative pressure in the intake port 13 increases due to the closing of the negative pressure generating valve 30, so that the reformed gas flow rate control valve 32 is set, for example, from the latter half of the exhaust stroke as shown in FIG. By opening a predetermined amount in the middle of the intake stroke, necessary and sufficient reformed gas is sucked into each cylinder with high accuracy.

  As described above, according to the internal combustion engine with a fuel reformer according to the third embodiment, the reformed gas flow rate control valve 32 is provided for each cylinder of the engine 10 so that necessary and sufficient reformed gas can be obtained. It can be supplied to each cylinder with high accuracy.

  In the third embodiment, the reformed gas flow rate control valve 32 is described as being opened from the latter half of the exhaust stroke to the middle intake stroke for each cylinder. However, the present invention is not limited to this, and at least during the intake stroke. I just need to speak.

  FIG. 9 is a schematic configuration diagram showing an internal combustion engine with a fuel reformer according to Embodiment 4 of the present invention, and FIG. 10 is a flowchart showing a control method.

  As shown in FIG. 9, in the fourth embodiment, in the configuration of the first embodiment (see FIG. 1), the fuel reforming catalyst 23 is located in the middle of the reformed gas supply passage 26 and upstream of the injector 24. An air pump 34 for pressure-feeding air is provided.

  Further, in the fourth embodiment, in order to suppress the reformed gas supplied from the air pump 34 from flowing back to the surge tank 19 side, and to prevent the reformed gas from flowing into the other cylinders, The provided negative pressure generation valve 30 is provided as a backflow suppression valve 40.

  That is, a backflow suppression valve 40 is provided in the middle of the intake passage 11 and upstream of the reformed gas supply unit 26a, and is configured to be controlled to be opened and closed by the ECU. Since the configuration of the backflow suppression valve 40 is the same as the configuration of the negative pressure generation valve 30, a duplicate description is omitted.

  Further, the control method by the backflow control valve 40 is basically the same as the control method of the negative pressure generating valve 30 shown in FIG. 2, and steps corresponding to the operation of the negative pressure generating valve 30 as shown in FIG. Steps S20 and S40 (see FIG. 2) are replaced with step S22 for closing the backflow suppression valve 40 and step S42 for opening the backflow suppression valve 40.

  That is, as shown in FIG. 10, when the engine 10 is started by the reformed gas (Yes at Step S10), the backflow suppression valve 40 is closed (Step S22), so that the reformed gas pumped by the air pump 34 is supplied to the surge tank 19. Backflow to the side can be suppressed, and flow into the other cylinders can be suppressed.

  When the current rotational speed of the engine 10 exceeds the predetermined rotational speed N1 (Yes at Step S30), it is determined that the air-fuel mixture in the cylinder has completely exploded, and the reverse flow suppression valve 40 is opened (Step S42), and control is performed. finish.

  On the other hand, the backflow suppression valve 40 is kept closed until it is determined that the air-fuel mixture in the cylinder has completely exploded (No at Step S30, Step S22).

  As described above, according to the internal combustion engine with the fuel reformer according to the fourth embodiment, the amount of the reformed gas to be supplied into the cylinder becomes misfired due to the backflow of the reformed gas. Can be prevented from deteriorating. Furthermore, it is possible to suppress the deterioration of emissions caused by the reformed gas flowing into the other cylinders.

  11 is a schematic configuration diagram showing an internal combustion engine with a fuel reformer according to Embodiment 5 of the present invention, and FIG. 12 is an internal combustion engine with a fuel reformer provided with a reformed gas flow rate control valve corresponding to each cylinder. It is a schematic block diagram which shows an engine.

  As shown in FIGS. 11 and 12, the fifth embodiment has a modified gas for controlling the flow rate of the reformed gas supplied to the intake system of the engine 10 in addition to the configuration of the fourth embodiment (see FIG. 1). A flow control valve 32 is provided for each cylinder of the engine 10.

  Further, the basic control method of the fifth embodiment is the same as the control method of the fourth embodiment (see FIG. 10). In addition, the timing for opening the reformed gas flow rate control valve 32 is set to the intake air of each cylinder. This is when the valve 15 is closed.

  If the reformed gas flow rate control valve 32 is opened to start supplying reformed gas while the intake valve 15 of each cylinder is open, sufficient reformed gas cannot be supplied into the cylinder during the intake stroke. This is because there is a risk of misfire and worsening of emissions.

  As described above, according to the internal combustion engine with a fuel reformer according to the fifth embodiment, the reverse flow of the reformed gas to the surge tank 19 is suppressed by closing the reverse flow suppression valve 40 when the engine 10 is started. It is possible to suppress a shortage of the supply amount of the reformed gas.

  Further, by opening the reformed gas flow rate control valve 32 and opening the reformed gas to each cylinder before opening the intake valve 15, necessary and sufficient reformed gas can be supplied into each cylinder with high accuracy. .

  As described above, the internal combustion engine with a fuel reformer according to the present invention is useful for an internal combustion engine that generates power by burning a mixture of reformed gas and air generated by the fuel reformer in a combustion chamber. In particular, it is suitable for an internal combustion engine that aims to easily supply necessary and sufficient reformed gas into the cylinder from the beginning of cranking when the internal combustion engine is started.

1 is a schematic configuration diagram showing an internal combustion engine with a fuel reformer according to Embodiment 1 of the present invention. It is a flowchart which shows a control method. It is side surface sectional drawing which shows the reformed gas supply part vicinity. It is a front view which shows the negative pressure production | generation valve | bulb in an intake passage. It is side surface sectional drawing which shows the reformed gas supply part vicinity of the internal combustion engine with a fuel reformer which concerns on Example 2 of this invention. It is a schematic block diagram which shows the internal combustion engine with a fuel reformer which concerns on Example 3 of this invention. It is a schematic block diagram showing an internal combustion engine with a fuel reformer provided with a reformed gas flow rate control valve corresponding to each cylinder. It is a conceptual diagram which shows the valve opening time of a reformed gas flow control valve. It is a schematic block diagram which shows the internal combustion engine with a fuel reformer which concerns on Example 4 of this invention. It is a flowchart which shows a control method. It is a schematic block diagram which shows the internal combustion engine with a fuel reformer which concerns on Example 5 of this invention. It is a schematic block diagram showing an internal combustion engine with a fuel reformer provided with a reformed gas flow rate control valve corresponding to each cylinder.

Explanation of symbols

10 Engine (Internal combustion engine)
DESCRIPTION OF SYMBOLS 10a Combustion chamber 11 Intake passage 13 Intake port 15 Intake valve 17 Injector 19 Surge tank 21 Throttle valve 22 Fuel reformer 23 Fuel reforming catalyst 24 Injector 26 Reformed gas supply passage 26a Reformed gas supply section 30 Negative pressure generating valve ( Intake flow control valve)
30b Valve opening 32 Reformed gas flow control valve 34 Air pump 40 Backflow control valve (intake flow control valve)

Claims (3)

A fuel reformer that reforms an air-fuel mixture of fuel and air to generate a reformed gas containing a predetermined fuel component and burns the air-fuel mixture of the reformed gas and air in a combustion chamber to generate power. In an internal combustion engine with a fuel reformer that is generated,
An intake passage connected to the intake port and including a throttle valve;
A reformed gas supply passage branched from the intake passage upstream of the throttle valve and supplying the reformed gas from the fuel reformer to the intake passage by a reformed gas supply section;
The reformer is disposed inside the intake passage on the downstream side of the throttle valve and upstream or near the upstream side of the reformed gas supply unit, and is closed when the internal combustion engine is started. An intake flow control valve that adjusts the supply amount or supply direction of the reformed gas supplied from the gas supply unit to the intake port;
An internal combustion engine with a fuel reformer.   2. The internal combustion engine with a fuel reformer according to claim 1, wherein the intake flow control valve includes a valve opening formed by notching the reformed gas supply unit.   The reformed gas supply passage is connected to each intake port, and a reformed gas flow rate control valve for adjusting the flow rate of the reformed gas is provided in the middle of the reformed gas supply passage. Item 3. An internal combustion engine with a fuel reformer according to Item 1 or 2.

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