JP2008121529A - Internal combustion engine system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine system capable of restraining the generation of a deposit with a structure for efficiently cooling an injector adopted in a cylinder direct injection type internal combustion engine. <P>SOLUTION: This internal combustion engine system 1 is applied with an exhaust gas recirculating device 50 to the cylinder direct injection type internal combustion engine 10. The exhaust gas recirculating device 50 has a cooling system including an exclusive cooler 53 and an exclusive radiator 55 independent of a cooling system 35 of the internal combustion engine 10. A feedback passage 56RE of a refrigerant coming out of the exclusive cooler is connected to the exclusive radiator 55 after passing through the vicinity of the injector 41 injecting fuel into a cylinder. Even if an EGR device is in a turned-on state or in a turned-off state, the generation of the deposit can be restrained by effectively cooling the injector. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an internal combustion engine system that employs an in-cylinder direct injection internal combustion engine. More specifically, the present invention relates to an internal combustion engine system that employs a technology (Exhaust Gas Recirculation technology) that recirculates a part of exhaust gas to the intake side. In the following description, the exhaust gas recirculation is referred to as an EGR process, and the exhaust gas recirculation device is referred to as an EGR device in the description.

  An in-cylinder direct injection internal combustion engine that directly injects fuel into a cylinder has been studied and put into practical use. An in-cylinder direct injection internal combustion engine can improve fuel efficiency and output as compared with a general internal combustion engine that injects fuel into an intake pipe or the like and guides an air-fuel mixture into the cylinder. However, in the case of an in-cylinder direct injection internal combustion engine, the injection hole of the injector that injects the fuel is disposed so as to face the inside of the cylinder (combustion chamber), and therefore, it is exposed to a high temperature. When the injection hole, which is the fuel outlet, is exposed to a high temperature, a deposit (deposit) in which a part of the fuel is solidified is likely to be generated. As a result, a decrease in the fuel injection amount or a change in the spray shape becomes a problem. In some cases, it is necessary to consider the suppression of deposits in an in-cylinder direct injection internal combustion engine.

  Thus, for example, Patent Document 1 proposes a structure of a fuel injection valve provided with a cooling mechanism that can cool the injection hole by surrounding the cooling water passage. If the injection holes can be forcibly cooled in this manner, the generation of deposits can be suppressed and changes in the injection amount and spray shape can be prevented. Further, in Patent Document 1, it is encouraged to divert the cooling path of the internal combustion engine (engine) and use it for cooling the injector, and the structure can be simplified by additionally providing the diverted path on the outer periphery of the injector. I am trying.

Japanese Patent Laid-Open No. 2004-28020

  However, the cooling water for the engine becomes high temperature depending on the operating condition of the engine. When the engine coolant becomes high temperature, the structure proposed in Patent Document 1 cannot cool the injector as expected. As a result, the above-described deposit is generated in the injector, causing a problem of a decrease in fuel injection amount and a change in spray shape. It is also conceivable to provide a unique cooling structure for cooling the injector. However, if the cooling structure is provided only for the injector cooling, the cost of the internal combustion engine system increases.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an internal combustion engine system that has a structure for efficiently cooling an injector employed in a direct injection type internal combustion engine and can suppress the generation of deposits.

  An object of the present invention is an internal combustion engine system in which an exhaust gas recirculation device is applied to a direct injection type internal combustion engine, wherein the exhaust gas recirculation device is independent of a cooling system of the internal combustion engine and a dedicated radiator. The refrigerant return path of the refrigerant exiting the dedicated cooler is connected to the dedicated radiator after passing through the vicinity of the injector that injects fuel into the cylinder. This can be achieved by an internal combustion engine system.

  According to the present invention, the cooling water passage for return is changed so that the refrigerant after cooling the dedicated cooler provided in the exhaust gas recirculation device (EGR device) passes through the vicinity of the injector and then returns to the dedicated radiator. To cool the injector efficiently. Since only a simple change is made to the existing structure, the present invention can be realized while suppressing the structure cost. In particular, when the EGR device is provided with a cooling system that is independent of the cooling system of the internal combustion engine in this way, a structure is adopted in which a cooling water passage returning from the EGR dedicated cooler is routed around the injector and cooled. When the EGR device is on or off, the injector can be effectively cooled to prevent deposits.

  An internal combustion engine system further comprising fuel injection control means for injecting fuel from the injector near the bottom dead center of the intake stroke when the internal combustion engine reaches a predetermined predetermined operating range, thereby enhancing the tumble flow It is good. In this case, by strengthening the tumble flow, it is possible to suppress the deposit of the injector even if the in-cylinder temperature rises.

  ADVANTAGE OF THE INVENTION According to this invention, the structure which cools the injector employ | adopted with the direct injection type internal combustion engine efficiently can be provided, and the internal combustion engine system which can suppress generation | occurrence | production of a deposit can be provided.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram schematically illustrating a configuration of an internal combustion engine system according to an embodiment. The internal combustion engine system 1 is configured around a direct injection type internal combustion engine (hereinafter simply referred to as the engine 10). The internal combustion engine system 1 includes an intake system 20 that supplies intake air to the engine 10, an exhaust system 30 that discharges exhaust gas generated in the engine 10, a fuel system 40 that supplies fuel to the engine 10, and the like. Yes.

  The intake system 20 includes an intake pipe 22 for supplying intake (air) AR to an intake manifold 21 disposed on the intake side of the engine 10. The intake pipe 22 includes an air cleaner 23 for filtering the intake AR from the upstream side, An air flow meter 24 for measuring the amount, a throttle valve 25 for adjusting the flow rate of intake air, a surge tank 26 for temporarily storing intake air, and the like are arranged.

  The exhaust system 30 includes an exhaust pipe 32 that sends out exhaust gas EG collected by an exhaust manifold 31 disposed on the exhaust side of the engine 10, and a three-way catalyst 33, a silencer (not shown), etc. are provided downstream of the exhaust pipe 32. Arranged appropriately. The exhaust manifold 31 is configured to merge exhaust from each cylinder, and an exhaust passage branched in correspondence with each cylinder is gathered in one exhaust pipe 32 on the downstream side. The three-way catalyst 33 is a purification device for purifying exhaust gas. The three-way catalyst 33 performs oxidation of hydrocarbons HC and carbon monoxide CO and reduction of nitrogen oxides NOx. The exhaust system 30 includes an A / F sensor 34A for linearly detecting the air-fuel ratio based on the oxygen concentration in the exhaust gas EG upstream of the three-way catalyst 33, and an exhaust gas EG downstream of the three-way catalyst 33. An oxygen sensor 34B is provided for detecting whether the air-fuel ratio is richer or leaner than the stoichiometric air-fuel ratio based on the oxygen concentration therein.

  The engine 10 is, for example, a direct injection internal combustion engine that includes six cylinders 11 as shown in the figure and injects fuel directly into each cylinder (fuel chamber). The fuel system 40 is configured to supply and inject fuel FE to each cylinder 11, and includes an injector (fuel injection valve) 41 provided in each cylinder, a fuel injection pump 42, a fuel tank 43, and the like. .

  The engine 10 has a cooling structure as in a general internal combustion engine. Specifically, a radiator 35 for cooling cooling water (refrigerant) supplied to a water jacket (not shown) formed in the cylinder block 12, a radiator pump 36 for pumping the cooling water, a pipe 37 connecting these, and the like A cooling structure is formed.

  The internal combustion engine system 1 employs an exhaust gas recirculation device 50 (hereinafter referred to as an EGR device 50) that recirculates exhaust gas. The EGR device 50 is a device that recirculates a part of the exhaust gas to the intake side. The EGR device 50 is employed with the intention of improving fuel efficiency, improving exhaust by reducing NOx and HC, and suppressing cooling loss by suppressing an excessive increase in the in-cylinder temperature. The EGR device 50 includes an EGR passage 51 that returns a part of the exhaust gas to the upstream side of the intake valve, an EGR valve 52 that opens and closes the EGR passage 51 as necessary, and an EGR cooler that cools EGR gas (exhaust gas to be recirculated). 53 is included.

  Here, a characteristic structure applied to the internal combustion engine system 1 will be described. In general, an EGR cooler cools EGR gas by passing a coolant such as cooling water cooled by a radiator. Heretofore, a configuration in which the cooling water of the radiator on the engine side is also passed through the EGR cooler and commonly used is conventionally used. On the other hand, in the internal combustion engine system 1, a radiator 55 dedicated for EGR is provided. A cooling water passage 56 for flowing cooling water to the EGR cooler 53 is connected to the radiator 55, and a cooling water pump 57 is provided in the cooling water passage 56. As described above, first, in the internal combustion engine system 1 of the present embodiment, the EGR device 50 includes a cooling system independently of the cooling system of the engine 10. Therefore, the EGR gas can be cooled as needed without being affected by the operating state (temperature change) of the engine 10. Therefore, when the EGR device 50 is started, the EGR gas can be sufficiently cooled and recirculated to the intake side. Thereby, the effect of suppressing deposits generated in the injector 41 can also be expected.

  In particular, in this internal combustion engine system 1, a cooling water passage 56RE for returning the refrigerant water that has exited the EGR cooler 53 to the radiator 55 is set as a new path that has not existed before. That is, the return cooling water passage 56RE exiting the EGR cooler 53 is set so as to return to the radiator 55 after passing through the vicinity of the injector 41 provided in each cylinder of the engine 10. In FIG. 1, the cooling water passages 56RE are illustrated in a simplified manner as being piped above the injectors 41. However, the cooling water passages 56RE are set to route around the outer circumferences of the injectors 41. May be.

  When the return cooling water passage 56RE is set as described above, when the EGR valve 52 is closed and the EGR processing is turned off (exhaust gas recirculation is turned off), the refrigerant temperature at the outlet of the EGR cooler 53 becomes equal to the inlet side temperature. It will be almost the same. In this case, the injector 41 can be sufficiently cooled. Therefore, the deposit deposited on the injector 41 can be suppressed.

  Contrary to the above case, when the EGR valve 52 is opened and the EGR process is turned on (exhaust gas recirculation is turned on), the EGR gas is cooled, so that the refrigerant temperature at the outlet of the EGR cooler rises. In this case, the temperature of the cooling water returned to the injector 41 rises as compared with the case where EGR is OFF. However, since the combustion temperature in the cylinder of the engine 10 is lowered by the EGR process being turned on, the heat reception of the injector 41 is reduced. Moreover, when the EGR process is turned on, NOx and HC in the cylinder are reduced. Therefore, even when the EGR process is on, depositing of the injector 41 can be suppressed as a result.

  As described above, when the EGR device 50 is provided with a cooling system that is independent of the engine cooling system, a cooling system is adopted in which the cooling water passage returning from the EGR cooler 53 is routed around the injector 41 for cooling. It is possible to suppress the occurrence of deposit even when the EGR process is ON or OFF. And the cooling water passage which makes the vicinity pass in order to cool the injector 41 only adds the change which manages the cooling water passage which returns the cooling water after cooling EGR to a radiator. That is, only simple changes are made to the existing structure. Therefore, in the case of the internal combustion engine system provided with the unique cooling system for the EGR device, the present invention can be realized without increasing the cost.

(Concrete example)
Further, an internal combustion engine system 2 to which the internal combustion engine system 1 of the first embodiment described above can be suitably applied will be described below with reference to FIGS. The engine included in the system 2 is also a direct injection type in which the tip (injection hole) of the injector is inserted into the cylinder. The internal combustion engine system 2 includes an engine configured to reinforce the tumble formation with the fuel injected from the injector when a predetermined operating range is reached.

  It is generally known that when the tumble flow is strengthened, the homogeneous combustion speed increases and the combustion temperature rises, so that deposits easily accumulate in the injection holes of the injector. It has also been confirmed that when the combustion temperature rises, the cooling loss increases and the fuel efficiency deteriorates. For such problems, (1) adopting a structure for lowering the temperature of the injector, (2) adopting an EGR device to lower the in-cylinder temperature, and the like can be considered. However, if the above (1) and (2) are individually realized, the number of parts increases, the structure becomes complicated, and the cost increases.

  However, the problem pointed out here can be solved by applying the structure of the first embodiment described above. That is, if the structure of the first embodiment is employed in an internal combustion engine system that employs a structure that enhances tumble, the occurrence of injector deposits can be suppressed. A specific example of the internal combustion engine system 2 described below is based on such a viewpoint.

  FIG. 2 is a diagram showing an internal combustion engine system 2 of a specific example, and in particular, this diagram is schematically shown so that a deployed cooling system can be confirmed. The internal combustion engine system 2 shown in FIG. 2 also has a peripheral structure as in the case of the internal combustion engine system 1 shown in FIG. 1, but is not shown here. Further, the same reference numerals are used for the portions corresponding to the parts shown in FIG. A radiator 35 for cooling the engine 60 is disposed as the first cooling system. The radiator 35 is connected to a water jacket 17 formed on the cylinder block 61 and the cylinder head 62 via a pipe 37.

  Further, the EGR device 50 is provided with an EGR radiator 55 for cooling the EGR cooler 53, and a cooling system independent of the cooling system of the engine 60 is provided. The return cooling water passage 56RE exiting the EGR cooler 53 is piped so as to return to the radiator 55 after passing through the cooling water passage 18 passing through the vicinity of the injector 16 formed in the cylinder head 62. The structure so far is almost the same as that of the first embodiment. The engine 60 has a structure for injecting fuel to enhance the tumble flow. Further, this point will be described with reference to FIG.

  FIG. 3 is a schematic diagram showing an enlarged configuration around the cylinder of the engine 60. The engine 60 includes a cylinder block 61, a cylinder head 62, a piston 63, a spark plug 64, an intake valve 65, and an exhaust valve 66. The engine 60 shown in this example is an in-line 4-cylinder in-cylinder spark ignition internal combustion engine. However, as long as the engine 60 is an in-cylinder direct injection type, the engine 60 may have other appropriate cylinder arrangement structure and number of cylinders.

  In FIG. 3, the main part of the engine 61 is shown with respect to the cylinder 61a as a representative of each cylinder, but the other cylinders have the same structure. The cylinder block 61 is formed with a substantially cylindrical cylinder 61a. A piston 63 is accommodated in the cylinder 61a. A cavity 63 a for guiding the tumble flow T is formed on the top surface of the piston 63. A cylinder head 62 is fixed to the upper surface of the cylinder block 61. The combustion chamber 67 is formed as a space surrounded by the cylinder block 61, the cylinder head 62 and the piston 63. In addition to an intake port 62a for introducing intake air to the combustion chamber 67, the cylinder head 62 is formed with an exhaust port 62b for exhausting the combusted gas from the combustion chamber 67. Further, the intake and exhaust ports 62a and 62b are opened and closed. Intake / exhaust valves 65 and 66 are provided. The engine 60 may have an intake / exhaust valve structure provided with an appropriate number of intake valves 65 and exhaust valves 66 per cylinder.

  The spark plug 64 is disposed in the cylinder head 62 with an electrode protruding substantially in the center above the combustion chamber 67. The injector 16 is also disposed in the cylinder head 62 with the fuel injection hole protruding into the combustion chamber 67 from a position adjacent to the spark plug 64 above the combustion chamber 67. The injection hole 16HL of the injector 16 is set so that the injected fuel FE reinforces the generation of the tumble flow T. A plurality of injectors 16 may be provided per cylinder.

  An airflow control valve 68 for generating a tumble flow T in the combustion chamber 67 is disposed in the intake port 62a. The air flow control valve 68 can generate a tumble flow T in the combustion chamber 67 by causing the intake air to drift in the intake port 62 a under the control of the ECU 69 described later. However, the means for generating the tumble flow for generating the tumble flow T in the combustion chamber 67 is not limited to the airflow control valve 68. For example, the shape of the intake port 62a formed so that the tumble flow T can be generated in the cylinder may be used. In particular, in this internal combustion engine system 2, the ECU 69 functions as a fuel injection control means, and when the predetermined operating range is reached, fuel is injected from the injector 16 in the vicinity of the bottom dead center of the intake stroke, and the tumble flow T To moderately strengthen.

  The ECU 69 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output circuit, and the like (not shown). The ECU 69 is mainly configured to control the engine 60. In this specific example, in addition to the supply / exhaust valves 65 and 66, the injector 16 and the fuel injection pump, the spark plug 64 and the airflow control valve 68 are also controlled. In addition to the injector 16 and the like, various control objects are connected to the ECU 69 via a drive circuit (not shown). Various sensors such as a crank angle sensor and a water temperature sensor accelerator sensor are connected to the ECU 69 so that the state of the engine 60 can be confirmed.

  The ROM is configured to store a program in which various processes executed by the CPU are described. In this example, in addition to the engine 60 control program, a fuel injection valve control program for controlling the injector 16 and the like are also provided. Storing. Therefore, as described above, the ECU 69 functions as a fuel injection control unit, and injects fuel from the injector 16 in the vicinity of the bottom dead center of the intake stroke when the engine 60 enters a predetermined operating region. The injected fuel moderately strengthens the tumble flow T, and the strengthened tumble flow T is maintained until the ignition timing. As a result, the turbulence of the air-fuel mixture increases at the ignition timing, and the combustion speed is improved moderately, so that good homogeneous combustion can be obtained.

  Here, when the tumble flow is strengthened as described above, deposits are easily deposited on the injector 16. However, the internal combustion engine system 2 includes the EGR device 50 as shown in FIG. 2, and the return cooling water passage from the EGR cooler 53 passes through the cooling water passage 18 passing around the injector provided in the cylinder head 62. After that, it is set so as to return to the radiator 55 dedicated to EGR. Therefore, the injector 16 can be effectively cooled in the same manner as described in the first embodiment, so that the deposit can be suppressed.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

It is the figure which showed typically the structure of the internal combustion engine system which concerns on an Example. It is the figure shown about the internal combustion engine system of the specific example. It is the schematic diagram which expanded and showed the structure around the cylinder of the engine in a specific example.

Explanation of symbols

1, 2 Internal combustion engine system 10, 60 Engine (Cylinder direct injection internal combustion engine)
16, 41 Injector 20 Fuel injection system 30 Exhaust system 40 Fuel system 50 EGR device (exhaust gas recirculation device)
53 EGR cooler (dedicated cooler)
55 EGR dedicated radiator (dedicated radiator)
69 ECU (fuel injection control means)
56RE Refrigerant Return Path

Claims (2)

An internal combustion engine system in which an exhaust gas recirculation device is applied to an in-cylinder direct injection internal combustion engine,
The exhaust gas recirculation device comprises a cooling system including a dedicated cooler and a dedicated radiator independent of the cooling system of the internal combustion engine;
The internal combustion engine system, wherein a return path of the refrigerant that has exited the dedicated cooler is connected to the dedicated radiator after passing through the vicinity of an injector that injects fuel into the cylinder. Fuel injection control means for intensifying tumble flow by injecting fuel from the injector near the bottom dead center of the intake stroke when the internal combustion engine reaches a predetermined predetermined operating range, The internal combustion engine system according to claim 1.

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