JP2008138688A - Fuel supply device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel supply device capable of improving high temperature startability of an internal combustion engine provided with a port injection injector and a cylinder injection injector. <P>SOLUTION: The fuel supply device 10 for an internal combustion engine 1 can supply the port injection injector 4p injecting fuel into an intake port and the cylinder injection injector 4c directly injecting fuel into a combustion chamber 2 with fuel from a fuel tank 11 by a fuel pump 12. The device is provided with a port injection delivery pipe 14p to which the port injection injector 4p is connected, a cylinder injection delivery pipe 14c to which the cylinder injection injector 4c is connected, and a fuel heating means 16 capable of heating fuel pressurized and fed by the fuel pump 12. Both of delivery pipes 14p. 14c are connected to the fuel pump 12 in parallel and the fuel heating means 16 is arranged to heat only fuel supplied to either of delivery pipes 14p, 14c. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel for an internal combustion engine that can supply fuel from a fuel tank by a fuel pump to a port injector that injects fuel into an intake port and an in-cylinder injector that directly injects fuel into a combustion chamber. It relates to a supply device.

  Conventionally, a returnless type fuel supply device that supplies high-pressure fuel to a combustion chamber of an internal combustion engine is known (see, for example, Patent Document 1). In this fuel supply apparatus, when the internal combustion engine is started, the fuel in the pressure accumulating pipe (fuel delivery pipe) is introduced into the pressurizing chamber of the high pressure pump and pressurized there. As a result, when the internal combustion engine is started, the fuel in the pressure accumulating pipe is pressurized by the high-pressure pump. It is possible to eliminate the vaporized fuel.

  Conventionally, in order to suppress fuel vaporization in the fuel system, a technique is known in which the fuel is cooled by a cooling fan until the temperature of the fuel becomes a predetermined value or less after the internal combustion engine is stopped (for example, Patent Document 2). reference.). Further, as a technique for suppressing fuel vaporization in the fuel system, there is also known a technique in which engine cooling water is guided to a regenerator when the internal combustion engine is stopped, and the heat of the engine cooling water is taken away by the regenerator (for example, , See Patent Document 3).

JP 2000-130288 A JP-A-63-88261 JP-A-6-17648

  However, even if the partially vaporized fuel is pressurized or cooled as described above, it is difficult to sufficiently dissipate the vaporized fuel. For example, in a state in which a part of the fuel is vaporized inside the fuel delivery pipe or the like, a sufficient fuel injection pressure cannot be ensured, and there is a possibility that the internal combustion engine cannot be started well. For this reason, an internal combustion engine including a conventional fuel supply device still has room for improvement in terms of so-called high temperature startability, and a port injection injector that injects fuel into the intake port, and fuel into the combustion chamber. A similar problem exists in an internal combustion engine that includes an in-cylinder injector that directly injects fuel.

  Therefore, an object of the present invention is to provide a fuel supply device that can improve the high temperature startability of an internal combustion engine that includes a port injection injector and an in-cylinder injector.

  The fuel supply device for an internal combustion engine according to the present invention has a fuel pump for injecting fuel from a fuel tank to a port injector for injecting fuel into an intake port and an in-cylinder injector for injecting fuel directly into a combustion chamber. In a fuel supply device for an internal combustion engine that can be supplied, a port injection delivery pipe connected to a port injection injector, a cylinder injection delivery pipe connected to a cylinder injection injector, and fuel pumped by a fuel pump The fuel injection means is capable of heating the port injection delivery pipe and the in-cylinder injection delivery pipe connected in parallel to the fuel pump, and the fuel heating means is the port injection delivery pipe and the in-cylinder injection pipe. It arrange | positions so that only the fuel supplied with respect to either one of a delivery pipe may be heated.

  In this fuel supply device, a port injection delivery pipe and an in-cylinder injection delivery pipe are connected in parallel to the fuel pump, and the fuel heating means determines which of the port injection delivery pipe and the in-cylinder injection delivery pipe. Only the fuel supplied to either is heated. Thereby, the fuel does not excessively rise in temperature inside the delivery pipe supplied with the fuel that is not heated by the fuel heating means among the port injection delivery pipe and the in-cylinder delivery delivery pipe. Vaporization of fuel in the delivery pipe is suppressed. Therefore, even when the temperature of the fuel at a predetermined location exceeds a predetermined value, the fuel is injected from the injector connected to the delivery pipe to which the fuel that is not heated by the fuel heating means is supplied. Thus, it is possible to secure a sufficient fuel injection pressure and improve the high-temperature startability of the internal combustion engine provided with the port injector and the in-cylinder injector.

  That is, the fuel supply device for an internal combustion engine according to the present invention includes a temperature detection means for acquiring the temperature of the fuel at a predetermined location, and the temperature of the fuel acquired using the temperature detection means when the internal combustion engine is started exceeds a predetermined value. Control means for injecting fuel from an injector connected to a delivery pipe supplied with fuel that is not heated by the fuel heating means out of the port injection delivery pipe and the in-cylinder delivery delivery pipe; Is preferably further provided.

  The fuel heating means preferably heats the fuel supplied to the delivery pipe to which the injector used when performing the lean combustion operation of the internal combustion engine is connected.

  Employing such a configuration makes it possible to further atomize the fuel injected from the injector during the lean combustion operation of the internal combustion engine to ensure stable combustion. Further, in such a configuration, since the fuel to the injector used at the start of the internal combustion engine is not heated, it is possible to secure a sufficient fuel injection pressure and improve the high temperature startability of the internal combustion engine.

  According to the present invention, it is possible to realize a fuel supply device that can improve the high-temperature startability of an internal combustion engine that includes a port injector and an in-cylinder injector.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is a schematic configuration diagram illustrating an internal combustion engine to which a fuel supply device according to a first embodiment is applied. The internal combustion engine 1 shown in the figure is configured as an in-line four-cylinder engine, and is preferably used as a travel drive source for a vehicle. The internal combustion engine 1 has a plurality of combustion chambers 2 formed in cylinder blocks, and burns fuel (in this embodiment, gasoline fuel) inside each combustion chamber 2 to reciprocate the piston 3. Generate power.

  As shown in FIG. 1, the internal combustion engine 1 faces a plurality of port injectors 4 p disposed on the cylinder head so as to face the corresponding intake ports, and faces the corresponding combustion chambers 2. A plurality of in-cylinder injectors 4c disposed in the cylinder head and a plurality of spark plugs (not shown) are provided. In the present embodiment, each port injector 4p is used when performing a lean combustion operation in which the air-fuel ratio of fuel and air in each combustion chamber 2 is larger (lean) than the stoichiometric air-fuel ratio under predetermined conditions. Each in-cylinder injector 4c is used when performing a stoichiometric combustion operation in which the air-fuel ratio of fuel and air in each combustion chamber 2 is maintained at a substantially stoichiometric air-fuel ratio under a predetermined condition.

  Each piston 3 of the internal combustion engine 1 is configured as a so-called deep dish top surface type, and a recess 3a is formed on the upper surface thereof. In the internal combustion engine 1, fuel is directed from each in-cylinder injector 4 c toward the recess 3 a of the piston 3 in each combustion chamber 2 in a state in which air is sucked into each combustion chamber 2 during the stoichiometric combustion operation. Is injected directly. Thus, in the internal combustion engine 1, a fuel / air mixture layer is formed (stratified) in the vicinity of a spark plug (not shown) in a state separated from the surrounding air layer. As a result, the internal combustion engine 1 can perform stable stratified combustion.

  In addition, an intake valve that opens and closes an intake port and an exhaust valve that opens and closes an exhaust port are disposed in the cylinder head of the internal combustion engine 1 for each combustion chamber 2. These intake valves and exhaust valves are opened and closed by a valve operating mechanism (not shown) having a variable valve timing function, for example. The intake port of each combustion chamber 2 is connected to an intake pipe (intake manifold) 5, and a drive-by-wire throttle valve 6 is installed in the intake pipe 5, for example. On the other hand, the exhaust port of each combustion chamber 2 is connected to an exhaust pipe (exhaust manifold) 7. In addition to the pre-catalyst device 8 including the three-way catalyst, the NOx occlusion reduction is provided in the exhaust pipe 7 in consideration of the increase in NOx (nitrogen oxide) in the exhaust gas accompanying the lean combustion operation of the internal combustion engine 1. A post-catalyst device 9 including a catalyst is connected. NOx in the exhaust gas from each combustion chamber 2 is occluded by the NOx occlusion reduction catalyst of the post-catalyst device 9, and the NOx occluded in the NOx occlusion reduction catalyst is reduced by a reduction process executed at a predetermined timing. .

  The fuel supply device 10 included in the internal combustion engine 1 described above includes a fuel tank 11, a fuel pump 12, a port injection delivery pipe 14p, and a cylinder in addition to the port injector 4p and the in-cylinder injector 4c described above. It includes an inner injection delivery pipe 14c. Each port injector 4p described above is connected to a port injection delivery pipe 14p, and each cylinder injection injector 4c described above is connected to a cylinder injection delivery pipe 14c.

  The fuel tank 11 stores gasoline fuel in a liquid phase state. The fuel pump 12 is disposed inside the fuel tank 11, sucks the fuel in the fuel tank 11, and discharges it at a predetermined pressure. One end of a fuel supply pipe L1 is connected to the discharge port of the fuel pump 12, and the other end of the fuel supply pipe L1 is connected to one end of a port injection delivery pipe 14p. The other end of the port injection delivery pipe 14p (the end opposite to the end where the fuel supply pipe L1 is connected) has a high-pressure pump 15 as a booster for boosting the fuel. The cylinder injection delivery pipe 14c is connected in series via the communication pipe L2.

  As a result, the fuel pump 12 is operated and each port injection injector 4p is appropriately opened, so that the liquid fuel in the fuel tank 11 is pumped to the port injection delivery pipe 14p. It becomes possible to inject fuel from the injector 4p for injection. Further, by operating both the fuel pump 12 and the high-pressure pump 15 and appropriately opening each in-cylinder injector 4c, the liquid fuel in the fuel tank 11 is supplied to the port injection delivery pipe 14p. Thus, fuel can be injected from each in-cylinder injector 4c by being pumped to the in-cylinder delivery pipe 14c.

  As shown in FIG. 1, a fuel heating unit 16 is installed in the middle of the fuel supply pipe L1 so as to be positioned between the fuel pump 12 and the port injection delivery pipe 14p. The fuel heating unit 16 is a heat exchanger that uses, for example, waste heat such as exhaust heat of the internal combustion engine 1 as a heat source, and is sucked out of the fuel tank 11 by the fuel pump 12 and delivered through the fuel supply pipe L1 to the port injection delivery pipe. The fuel pumped to 14p can be heated. In this way, by heating the fuel supplied from the fuel tank 11 to the port injection delivery pipe 14p, the fuel injected from each port injector 4p used during the lean combustion operation is further atomized. It is possible to extend the so-called lean limit.

  The above-described fuel supply device 10 is controlled by an electronic control unit (hereinafter referred to as “ECU”) 20 that functions as a control unit of the internal combustion engine 1. The ECU 20 includes a CPU, a ROM, a RAM, an input / output port, a storage device, and the like, all not shown, and various sensors including the water temperature sensor 21 are connected to the input / output port of the ECU 20. Further, as shown in FIG. 1, each port injector 4p, each in-cylinder injector 4c, the fuel pump 12 of the fuel supply device 10, the high-pressure pump 15 and the like are connected to the input / output ports of the ECU 20. These are controlled by the ECU 20.

  Now, in the internal combustion engine 1 described above, especially when the fuel in the fuel supply pipe L1 is heated using the fuel heating unit 16, the engine temperature (the temperature of the cylinder head and the cylinder block) increases, particularly when the engine is stopped. The fuel is easily vaporized in each port injection injector 4p, the port injection delivery pipe 14p, and the like. When the internal combustion engine 1 is to be restarted in such a high engine temperature (fuel temperature) state, sufficient fuel injection pressure is ensured by the presence of fuel vaporized inside the port injection delivery pipe 14p and the like. There is a possibility that the internal combustion engine 1 cannot be started well.

For this reason, in the internal combustion engine 1 of the present embodiment, when the ignition switch is turned on, the ECU 20 is based on a signal from the water temperature sensor 21, for example, fuel in each port injector 4p or port injection delivery pipe 14p. determines the acquired temperature T _F, whether acquired temperature T _F is greater than the threshold T _R of a predetermined. Then, ECU 20, when the fuel temperature T _F is determined to exceed the threshold T _R of predetermined, the fuel pump 12 is operated a high-pressure pump 15, Further, the fuel injection from the injector 4p for each port injection In the stopped state, fuel is injected into each combustion chamber 2 from the in-cylinder injector 4c.

As described above, if the fuel is injected from each in-cylinder injector 4c into the combustion chamber 2 while the fuel pump 12 and the high-pressure pump 15 are operated, the inside of the port injection delivery pipe 14p and the like The fuel present in the fuel is boosted by a high-pressure pump 15 as a boosting means, then sent to the in-cylinder delivery pipe 14c, and injected into the combustion chamber 2 from each in-cylinder injector 4c. become. Therefore, according to the fuel supply device 10, when to the original starting the internal combustion engine 1 in the high temperature state in which the fuel temperature T _F is over the threshold T _R (restart), in the interior of the port injection delivery pipe 14p Even if the fuel is vaporized, the high-pressure pump 15 is operated and fuel is injected from the in-cylinder injector 4c into the combustion chamber 2 to thereby remove the vaporized fuel that hinders the startability of the internal combustion engine 1. Since a sufficient fuel injection pressure can be ensured by increasing the pressure and liquefying, the high temperature startability of the internal combustion engine 1 can be improved even when the fuel heating unit 16 is used.

[Second Embodiment]
Hereinafter, the second embodiment will be described with reference to FIG. The same elements as those described in relation to the first embodiment described above are denoted by the same reference numerals, and redundant description is omitted.

  The internal combustion engine 1A to which the fuel supply device 10A shown in FIG. 2 is applied also includes a plurality of port injectors 4p and a plurality of in-cylinder injectors 4c. Also in this embodiment, each port injector 4p performs a lean combustion operation in which the air-fuel ratio of fuel and air in each combustion chamber 2 is larger than the stoichiometric air-fuel ratio (lean) under a predetermined condition. Each in-cylinder injector 4c is used when performing a stoichiometric combustion operation in which the air-fuel ratio of fuel and air in each combustion chamber 2 is maintained at a substantially stoichiometric air-fuel ratio under a predetermined condition.

  In the fuel supply device 10A, instead of the in-cylinder delivery pipe 14c connected in series to the port injection delivery pipe 14p connected to the fuel pump 12 via the high-pressure pump 15, the port injection delivery pipe 14p is connected. And an in-cylinder injection delivery pipe 14 c are connected to the fuel pump 12 in parallel. That is, the fuel supply pipe L1 connected to the discharge port of the fuel pump 12 is branched in two directions at a branch portion BP provided in the middle of the fuel pump 12, and port injection is performed on one branch pipe L1p of the fuel supply pipe L1. The delivery pipe for pipe 14p is connected, and the in-cylinder injection delivery pipe 14c is connected to the other branch pipe L1c of the fuel supply pipe L1.

  Further, a fuel heating unit 16 is installed in one branch pipe L1p of the fuel supply pipe L1 so as to be positioned between the branch portion BP and the port injection delivery pipe 14p. Therefore, in the present embodiment, only the fuel supplied from the fuel tank 11 to the port injection delivery pipe 14 p is heated by the fuel heating unit 16. Furthermore, a high-pressure pump 15 for boosting the fuel to each in-cylinder injector 4c is incorporated in the middle of the other branch pipe L1c of the fuel supply pipe L1.

  In the fuel supply apparatus 10A configured as described above, only the fuel supplied to the port injection delivery pipe 14p by the fuel heating unit 16 is heated. Therefore, in the cylinder injection delivery pipe 14c to which fuel that is not heated by the fuel heating unit 16 is supplied, the temperature of the fuel is not excessively increased, and the cylinder injection delivery pipe 14c is not heated. Fuel vaporization will be suppressed.

In view of such a point, in the internal combustion engine 1A of the present embodiment, when the ignition switch is turned on, the ECU 20 is based on a signal from the water temperature sensor 21, for example, in each port injector 4p or in the port injection delivery. get the temperature T _F of the fuel in the tube 14p, determines whether the acquired temperature T _F is greater than the threshold T _R determined in advance. Here, if the fuel temperature T _F is over the threshold T _R, the inside of the port injection for delivery pipe 14p may be the fuel is vaporized. Therefore, ECU 20, when the fuel temperature T _F is determined to exceed the threshold T _R of predetermined, the fuel pump 12 is operated a high-pressure pump 15, The fuel injection from the injector 4p for each port injection The fuel is injected into each combustion chamber 2 from the in-cylinder injector 4c in a state where the fuel injection is stopped.

Thus, when for the original start the internal combustion engine 1 in the high temperature state in which the fuel temperature T _F of the above exceeds the threshold value T _R (restart), the relatively low temperature of the fuel which is not heated by the fuel heating unit 16 If fuel is injected into the combustion chamber 2 from each in-cylinder injector 4c connected to the supplied in-cylinder delivery pipe 14c, the branch pipe L1c of the fuel supply pipe L1 and the in-cylinder injection delivery are provided. Since there is almost no vaporized fuel inside the pipe 14c, even when the fuel heating unit 16 is used, a sufficient fuel injection pressure is ensured, and the high-temperature startability of the internal combustion engine 1 can be ensured. Can be improved.

  Further, since the fuel pressurized by the high-pressure pump 15 is supplied to the in-cylinder delivery pipe 14c, the vaporization of the fuel inside the in-cylinder delivery pipe 14c is extremely reliably suppressed. become. Then, as in the present embodiment, only the fuel supplied to the port injection delivery pipe 14p to which the port injection injector 4p used when the lean combustion operation of the internal combustion engine 1 is executed is connected by the fuel heating unit 16. By heating, in the lean combustion operation of the internal combustion engine 1, the fuel injected from each port injector 4p is further atomized to ensure stable combustion and used when the internal combustion engine 1 is restarted. It is possible to suppress the temperature rise of the fuel to each in-cylinder injector 4c as much as possible.

1 is a schematic configuration diagram illustrating an internal combustion engine to which a fuel supply device according to a first embodiment is applied. It is a schematic block diagram which shows the internal combustion engine to which the fuel supply apparatus which concerns on 2nd Embodiment was applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1A Internal combustion engine 2 Combustion chamber 3 Piston 4c In-cylinder injector 4p Injector for port injection 5 Intake pipe 6 Throttle valve 7 Exhaust pipe 8 Pre-stage catalyst apparatus 9 Post-stage catalyst apparatus 10, 10A Fuel supply apparatus 11 Fuel tank 12 Fuel pump 14c Delivery pipe for in-cylinder injection 14p Delivery pipe for port injection 15 High-pressure pump 16 Fuel heating unit 20 ECU
21 Water temperature sensor BP Branch part L1 Fuel supply pipe L1c, L1p Branch pipe L2 Communication pipe

Claims (3)

In a fuel supply device for an internal combustion engine capable of supplying fuel from a fuel tank by a fuel pump to a port injection injector that injects fuel into an intake port and an in-cylinder injector that directly injects fuel into a combustion chamber.
A port injection delivery pipe to which the port injector is connected;
An in-cylinder delivery pipe connected to the in-cylinder injector;
Fuel heating means capable of heating the fuel pumped by the fuel pump,
The port injection delivery pipe and the in-cylinder injection delivery pipe are connected in parallel to the fuel pump, and the fuel heating means includes any one of the port injection delivery pipe and the in-cylinder injection delivery pipe. A fuel supply device for an internal combustion engine, wherein the fuel supply device is arranged so as to heat only the fuel supplied to one of them. Temperature detection means for acquiring the temperature of the fuel at a predetermined location;
When the temperature of the fuel acquired using the temperature detecting means at the time of starting the internal combustion engine exceeds a predetermined value, the fuel heating means out of the port injection delivery pipe and the in-cylinder injection delivery pipe 2. The fuel supply apparatus for an internal combustion engine according to claim 1, further comprising control means for injecting fuel from an injector connected to a delivery pipe to which unheated fuel is supplied.   2. The fuel for an internal combustion engine according to claim 1, wherein the fuel heating unit heats the fuel supplied to a delivery pipe to which an injector used when performing the lean combustion operation of the internal combustion engine is connected. Feeding device.

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