JP2005315234A - Internal combustion engine and control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress deterioration of emission and drop of performance in an operation condition where combustion temperature gets high. <P>SOLUTION: This internal combustion engine 1 is a reciprocating internal combustion engine provided with a water injection valve 3. Water I is supplied to a combustion chamber 1b by injecting water from the water injection valve 3. Timing of water injection from the water injection valve 3 is in a period of overlap of open timing of an intake valve 8i and close timing of an exhaust valve 8e. The combustion chamber 1b of the internal combustion engine 1 is cooled by injecting water from the water injection valve 3 during the overlap period and the injected water passes through an exhaust system of the internal combustion engine 1 to cool exhaust gas. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an internal combustion engine that injects water into a combustion chamber. More specifically, the present invention relates to an internal combustion engine and a control device for the internal combustion engine that can suppress deterioration in emissions and performance degradation under operating conditions in which the combustion temperature increases.

  In a diesel engine which is a kind of internal combustion engine, a technique is used in which NOx is removed by lowering the combustion temperature by injecting water into an intake pipe. For example, in Patent Document 1, auxiliary fuel and water are injected into the intake pipe, and combustion by main injection in the compression stroke is promoted by the auxiliary fuel to reduce soot. A technique for reducing NOx by lowering the combustion temperature by water injection is disclosed.

JP-A-5-65854

  By the way, in the internal combustion engine, the exhaust temperature becomes high because the combustion temperature becomes high at the time of high rotation and high load. Also, knocking is likely to occur. For this reason, in such operating conditions where the exhaust temperature tends to be high, the ignition system is retarded or the amount of fuel is increased (air-fuel is rich) to protect the exhaust system and prevent knocking. ing.

  However, if the ignition timing is retarded or the amount of fuel is increased, the emission may be deteriorated or the performance of the internal combustion engine may be deteriorated. In the technique disclosed in Patent Document 1, soot and NOx can be reduced, but there is room for improvement in order to suppress the deterioration of emissions and performance under operating conditions in which the combustion temperature is high, such as at high rotation and high load. is there. Therefore, the present invention has been made in view of the above, and is an internal combustion engine and an internal combustion engine that can suppress deterioration in emissions and performance deterioration under operating conditions in which the combustion temperature becomes high, such as at high rotation and high load. An object is to provide a control device.

  In order to solve the above-described problems and achieve the object, an internal combustion engine according to the present invention is a reciprocating internal combustion engine including an intake valve and an exhaust valve, and the timing when the intake valve opens and the exhaust valve It is characterized by comprising water injection means for supplying water to the combustion chamber of the internal combustion engine by injecting water during a period in which it overlaps with the closing time of the engine.

  The internal combustion engine according to the present invention is characterized in that, in the internal combustion engine, when the exhaust temperature of the internal combustion engine is equal to or higher than a predetermined upper limit value of the exhaust temperature, water is injected from the water injection means.

  The internal combustion engine according to the present invention is characterized in that, in the internal combustion engine, the period of overlap is increased during water injection by the water injection means.

  The internal combustion engine according to the next aspect of the present invention is characterized in that, in the internal combustion engine, the amount of water injected by the water injection means is changed based on the exhaust gas temperature.

  The internal combustion engine according to the present invention is characterized in that, in the internal combustion engine, a fuel injection amount for the internal combustion engine is changed based on the exhaust gas temperature.

  A control apparatus for an internal combustion engine according to the present invention for controlling a reciprocating internal combustion engine comprising an intake valve, an exhaust valve, and water injection means for supplying water to a combustion chamber. An exhaust temperature determination unit for determining an exhaust temperature; and, when the exhaust temperature is equal to or higher than a predetermined exhaust temperature upper limit, the water injection means during a period in which the timing when the intake valve opens and the timing when the exhaust valve closes overlap And a water injection timing determination unit that determines the water injection timing of the water injection means so as to inject water.

  The internal combustion engine control apparatus according to the present invention is the internal combustion engine control apparatus, wherein the intake valve is opened to increase the overlap period during the water injection by the water injection means. Alternatively, a valve opening / closing timing determining unit that determines at least one of the closing timings of the exhaust valve is provided.

  The internal combustion engine control apparatus according to the present invention is a water injection system for increasing the water injection amount until the exhaust temperature determination unit determines that the exhaust gas temperature tends to rise in the internal combustion engine control apparatus. A quantity determining unit is provided.

  The internal combustion engine control device according to the next aspect of the present invention stops the increase in the water injection amount when the exhaust gas temperature determination unit determines that the exhaust gas temperature is increasing in the internal combustion engine control device. A water injection amount determination unit for performing the operation.

  The internal combustion engine control device according to the present invention is directed to the internal combustion engine control device when the exhaust temperature determination unit determines that the exhaust temperature is lower than a predetermined target temperature. A fuel injection amount determining unit for reducing the fuel injection amount is provided.

  As described above, in the internal combustion engine and the control device for the internal combustion engine according to the present invention, it is possible to suppress the deterioration of the emission and the deterioration of the performance under the operating condition where the combustion temperature becomes high.

  Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited to the best mode for carrying out the invention. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same. The present invention can be preferably applied to an internal combustion engine including a supercharging device, and is particularly preferable for an internal combustion engine mounted on a vehicle such as a passenger car, a bus, or a truck.

  Embodiment 1 is an internal combustion engine including water injection means for supplying water to a combustion chamber, and water is injected from the water injection means during an overlap period between the timing when the exhaust valve closes and the timing when the intake valve opens. This is characterized in that water is supplied to the combustion chamber. Next, the internal combustion engine according to the first embodiment will be described. FIG. 1 is a cross-sectional view of one cylinder included in the internal combustion engine according to the first embodiment. First, the configuration of the internal combustion engine according to the first embodiment will be described with reference to FIG.

  As shown in FIG. 1, the internal combustion engine 1 according to the first embodiment includes water injection means for allowing water to reach the combustion chamber 1b. The piston 5 reciprocates in the cylinder 1s, and the crankshaft 6 Thus, the reciprocating motion of the piston 5 is converted into a rotational motion. The internal combustion engine 1 is mounted on a passenger car, truck, or other vehicle, and serves as a power source for the vehicle. Although the internal combustion engine 1 according to the first embodiment shows only one cylinder, the internal combustion engine to which the present invention can be applied is not limited to a single cylinder or multiple cylinders. In addition, the present invention only needs to include water injection means for allowing water to reach the combustion chamber 1b. If these conditions are satisfied, either a spark ignition type or a diesel type internal combustion engine can be applied, a supercharger may be provided, and a rotary internal combustion engine may also be used.

  An internal combustion engine 1 described in the following embodiments is a reciprocating internal combustion engine, which is a so-called spark ignition internal combustion engine that ignites an air-fuel mixture in a combustion chamber 1b by a spark plug 7. The internal combustion engine 1 includes a port injection valve 2 that injects fuel F into an intake port 4 constituting an intake passage. Then, the fuel F is supplied to the internal combustion engine 1 by the port injection valve 2. The present invention can also be applied to a so-called direct injection internal combustion engine that is a spark ignition type and includes a direct injection valve that directly injects fuel into the combustion chamber 1b.

  The intake system of the internal combustion engine 1 includes an intake passage 21, an air cleaner 22 provided in the middle of the intake passage 21, an electronic throttle valve 70 also provided in the middle of the intake passage 21, an intake passage 21, and an intake valve of the internal combustion engine 1. 8i and the intake port 4 provided between 8i. The exhaust system of the internal combustion engine 1 includes an exhaust port 9, a catalyst 25 provided downstream of the exhaust port 9, an exhaust port 9 and the catalyst 25, and an exhaust passage 24 connecting the catalyst 25 and the silencer 26. Is done. Here, “downstream” means downstream in the flow direction of the exhaust Ex.

  In the internal combustion engine 1, the intake air amount is adjusted by an electronic throttle valve 70 provided in the intake passage 21. The electronic throttle valve 70 includes a butterfly valve 71, an actuator 72 that drives the butterfly valve 71, and an opening degree sensor 73 that detects the opening degree of the butterfly valve 71. The engine ECU 30 acquires the output from the accelerator opening sensor 42, sends a control signal to the actuator 72, and sets the butterfly valve 71 to an appropriate opening based on the feedback signal of the butterfly valve opening from the opening sensor 73. To control.

  An intake valve 8i and an exhaust valve 8e are attached to the cylinder head 1h of the internal combustion engine 1, and are driven by an intake cam 62i of the intake camshaft 61i and an exhaust cam 62e of the exhaust camshaft 61e to open and close. By opening the intake valve 8i, an air-fuel mixture of the air A and the fuel F injected from the port injection valve 2 is introduced into the combustion chamber 1b. Thereafter, the intake valve 8i is closed, and the air-fuel mixture in the combustion chamber 1b is compressed in the process of moving the piston 5 toward TDC (Top Death Center).

  At the timing before and after the piston 5 reaches TDC (ignition top dead center), the spark plug 7 attached to the cylinder head 1h of the internal combustion engine 1 discharges, ignites the air-fuel mixture introduced into the combustion chamber 1b, and flame Burn by propagation. The combustion pressure of the air-fuel mixture is transmitted to the piston 5 and causes the piston 5 to reciprocate. The reciprocating motion of the piston 5 is transmitted to the crankshaft 6 via the connecting rod 6c, where it is converted into rotational motion. The crankshaft 6 takes out the reciprocating motion of the piston 5 as an output of the internal combustion engine 1.

  The air-fuel mixture after combustion becomes exhaust Ex. The exhaust Ex is discharged from the combustion chamber to the exhaust port 9 when the exhaust valve 8e is opened. The exhaust Ex is guided to the catalyst 25 through the exhaust passage 24 constituting the exhaust system of the internal combustion engine 1 and purified there. An exhaust temperature sensor 46 is attached between the exhaust port 9 and the catalyst 25, and the temperature of the exhaust Ex is monitored and used for water injection control or whether the catalyst 25 is used within an allowable temperature. Or not. The exhaust Ex purified by the catalyst 25 is guided to the silencer 26 through the exhaust passage 24 and is released to the atmosphere after noise is reduced.

  A water injection valve 3 as water injection means for supplying water to the combustion chamber 1b is attached to the cylinder head 1h of the internal combustion engine 1 according to the first embodiment. By injecting water from the water injection valve 3, the internal combustion engine 1 according to the first embodiment can supply water directly into the combustion chamber 1b. By directly injecting water into the combustion chamber 1b, the temperature in the combustion chamber 1b can be quickly reduced, so that the internal combustion engine 1 can be used under operating conditions in which the combustion temperature becomes high, such as at high rotation and high load. It is effective in suppressing the performance degradation and emission deterioration. The water injection valve 3 may be attached to the intake port 4 of the internal combustion engine 1 to inject water W into the intake port. The water injection valve 3 injects water W into the combustion chamber 1b. The timing for injecting water W from the water injection valve 3 is determined according to the operating conditions of the internal combustion engine 1.

  2-1 is explanatory drawing which shows the water supply system to a water injection valve. FIG. 2-2 is a cross-sectional view showing a structural example of a water injection valve. The water W stored in the water tank 50 is sent to the water supply pipe 52 by the feed pump 51. The water injection valve 3 is attached to a water supply pipe 52, and water W is supplied from the water supply pipe 52. This water W is filled in a water passage 3r formed between the inner surface 3i of the water injection valve 3 and the needle valve 3n. A relief valve 54 is attached to the water supply pipe 52, and excess water W is returned to the water tank 50 to keep the pressure in the water supply pipe 52 constant. Here, the pressure in the water supply pipe 52 is maintained at several hundred kPa.

  When a water injection command is given from the engine ECU 30 to the water injection valve 3, the solenoid coil 3c attached to the water injection valve 3 is energized. Then, the needle valve 3n, which is biased against the valve seat 3b by the spring 3s, moves in the direction opposite to the water injection hole 3p (the direction of arrow A in FIG. 2-2) by the electromagnetic force generated in the solenoid coil 3c. . Thereby, the water passage 3r in the water injection valve 3 and the water injection hole 3p communicate with each other, and the water W in the water passage 3r is injected from the water injection hole 3p.

  A crank angle sensor 41 is attached to the crankshaft 6 of the internal combustion engine 1. In order to control the timing at which the water injection valve 3 injects the water W and the port injection valve 2 injects the fuel F by the engine ECU (Engine Control Unit) 30 acquiring the output of the crank angle sensor 41. use. Further, the engine speed of the internal combustion engine 1 can be obtained based on the signal from the crank angle sensor 41. Further, the engine ECU 30 acquires outputs from the crank angle sensor 41, the accelerator opening sensor 42, the air flow sensor 43, the intake air temperature sensor 44, the water temperature sensor 45, the exhaust gas temperature sensor 46, and other various sensors, and Control driving.

FIGS. 3A and 3B are explanatory diagrams illustrating the timing of water injection. The internal combustion engine 1 according to the first embodiment has a valve opening timing IVO (Intake Valve Open: θ _{1 in} FIG. 3A) of the intake valve 8i and a valve closing timing EVC (Exhaust Valve Close: FIG. 3) of the exhaust valve 8e. 1 (θ _{2 in} 1) overlaps with water (hereinafter, overlap period: θo _{1 in} FIG. 3A), water W is injected from the water injection valve 3. The overlap period is a portion indicated by hatching in FIG. Thereby, since the inside of the combustion chamber 1b can be cooled with the water W injected from the water injection valve 3, the amount of intake air can be increased. As a result, the volume efficiency can be improved and the performance of the internal combustion engine 1 can be improved. Moreover, since the internal combustion engine 1 can be cooled, the fuel increase for cooling can be suppressed and fuel consumption can be suppressed.

  Further, since the water W injected from the water injection valve 3 during the overlap period blows through the exhaust valve 8e to the exhaust system of the internal combustion engine 1, the exhaust Ex can be cooled. Thereby, the emission can be improved. In particular, in the operation region where the exhaust gas temperature is high, such as during high rotation and high load operation, the volume efficiency can be improved by water injection, and the exhaust gas can be cooled. Thereby, in such a driving | running area | region, the performance fall of the internal combustion engine 1 and the deterioration of an emission can be suppressed effectively.

  It is preferable that the internal combustion engine 1 according to the first embodiment can change the opening / closing timing of at least one of the intake valve 8i and the exhaust valve 8e. FIG. 4 is an explanatory diagram showing an example of a mechanism for changing the opening / closing timing of the intake valve and the exhaust valve. In FIG. 4, the intake side represents a retarded state, and the exhaust side represents an advanced state. The opening / closing timing of the intake valve 8i and the exhaust valve 8e can be changed by the mechanism shown in FIG. This mechanism will be briefly described. The intake side housing 64i is fixed to the intake side driven gear 63i, and the exhaust side housing 64e is fixed to the exhaust side driven gear 63e. The intake side vane portion 65i is fixed to the intake camshaft 61i, and the exhaust side vane portion 65e is fixed to the exhaust camshaft 61e.

  In the space between the intake side housing 64i and the intake side vane portion 65i and the space between the exhaust side housing 64e and the exhaust side vane portion 65e, an intake side advance chamber 66i, an intake side retard chamber 67i, and An exhaust side advance chamber 66e and an exhaust side retard chamber 67e are formed. Cam hydraulic oil is supplied to the intake side advance chamber 66i, the exhaust side advance chamber 66e, etc., and by controlling the hydraulic pressure of the cam hydraulic oil acting on the advance chamber and retard chamber, the intake side vane portion 65i or The exhaust side vane portion 65e is rotated to continuously change the phase of the intake camshaft 61i or the exhaust camshaft 61e.

  When the internal combustion engine 1 according to the first embodiment includes the above mechanism, when water is injected from the water injection valve 3 during the overlap period, it is preferable to increase the overlap period by changing the timing of IVO or EVC. . This is because the temperature of the exhaust gas decreases due to water injection and the exhaust gas pressure decreases, so that the volume efficiency can be improved by increasing the overlap period. When the overlap period is increased, the IVO or EVC timing is changed with respect to the same load as that before the overlap period is increased.

  In increasing the overlap period, it is preferable to increase the overlap period by shifting the valve opening timing IVO of the intake valve 8i to an advance side from the TDC (see the dotted line in FIG. 3-1). This is due to the following reason. That is, by performing water injection during the overlap period, the temperature in the combustion chamber 1b can be reduced, and the pressure in the combustion chamber 1b can be quickly reduced. As a result, it is possible to extend the overlap period by opening the intake valve 8i earlier, introduce more air into the combustion chamber 1b, and efficiently suppress the performance degradation of the internal combustion engine 1.

Here, the valve closing timing EVC of the exhaust valve 8e is shifted from the TDC to the retard side, that is, as shown by the two-dot chain line in FIG. 3-1, the overlap period is delayed. It may be increased. As a result, the amount of water W that blows into the exhaust system of the internal combustion engine 1 increases, so that the exhaust Ex can be further cooled and the emission deterioration can be more effectively suppressed. Further, the overlap period may be increased by shifting the IVO timing of the intake valve 8i to the advance side and shifting the EVC timing of the exhaust valve 8e to the retard side (FIG. 3A). Of θo ₂ ). As a result, the amount of air introduced into the combustion chamber 1b can be increased and the exhaust temperature can be lowered. Here, the increase amount of the overlap period is about 10 degrees to 20 degrees in terms of the crank angle CA.

  Next, control of the internal combustion engine according to the first embodiment will be described. FIG. 5 is an explanatory diagram illustrating the configuration of the control device for the internal combustion engine according to the first embodiment. The control method of the internal combustion engine according to the first embodiment can be realized by the control device 10 for the internal combustion engine according to the first embodiment. The control device 10 for an internal combustion engine is built in an engine ECU 30. Separately from the engine ECU 30, the control device 10 for the internal combustion engine according to the first embodiment may be prepared and connected to the engine ECU 30. In realizing the control method of the internal combustion engine according to the first embodiment, the control function of the internal combustion engine 1 provided in the engine ECU 30 may be configured so that the control device 10 of the internal combustion engine can be used.

  The control device 10 for an internal combustion engine includes an exhaust temperature determination unit 11, a water injection amount determination unit 12, a water injection timing determination unit 13, a valve opening / closing timing determination unit 14, and a water injection control unit 15. Is done. These are the parts that execute the control method for the internal combustion engine according to the first embodiment. The exhaust temperature determination unit 11, the water injection amount determination unit 12, the water injection timing determination unit 13, the valve opening / closing timing determination unit 14, and the water injection control unit 15 are input / output ports ( I / O) 19 is connected. As a result, the exhaust temperature determination unit 11, the water injection amount determination unit 12, the water injection timing determination unit 13, the valve opening / closing timing determination unit 14, and the water injection control unit 15 can exchange data in both directions. Configured as follows. In addition, you may comprise so that data may be transmitted / received in one direction as needed on an apparatus structure (the following is the same).

  The control device 10 of the internal combustion engine, the processing unit 30p of the engine ECU 30, and the storage unit 30m are connected via an input / output port (I / O) 19 provided in the engine ECU 30, and data is mutually transmitted between them. Can communicate. Thereby, the control device 10 of the internal combustion engine acquires the load of the internal combustion engine 1 or the like of the engine ECU 30, the engine speed, and other operation control data of the internal combustion engine, or controls the control device 10 of the internal combustion engine to control the internal combustion engine of the engine ECU 30. It is possible to interrupt the engine operation control routine.

  In addition, the input / output port (I / O) 19 is connected to various sensors for acquiring information related to the operating state of the internal combustion engine 1, such as a crank angle sensor 41, an accelerator opening sensor 42, an exhaust temperature sensor 46, and the like. Yes. Thereby, the engine ECU 30 and the control device 10 for the internal combustion engine can acquire information necessary for operation control of the internal combustion engine 1 and the like. The input / output port (I / O) 19 is connected to the water injection valve 3, the valve opening / closing timing control mechanism 60, and other controlled objects, and the water injection timing determining unit 13 of the control device 10 for the internal combustion engine, These operations can be controlled by control signals from the injection control unit 15 and the processing unit 30p of the engine ECU 30.

  The storage unit 30m stores a computer program including processing procedures of the control method of the internal combustion engine according to the first embodiment, a fuel injection amount data map used for operation control of the internal combustion engine 1, and the like. Here, the storage unit 30m can be configured by a volatile memory such as a RAM (Random Access Memory), a nonvolatile memory such as a flash memory, or a combination thereof. Further, the control device 10 of the internal combustion engine and the processing unit 30p of the engine ECU 30 can be configured by a memory and a CPU.

  The computer program can realize the processing procedure of the control method for the internal combustion engine according to the first embodiment, in combination with the computer program already recorded in the water injection timing determination unit 13, the water injection control unit 15, and the like. There may be. Moreover, this internal combustion engine control apparatus 10 may implement | achieve the functions of the water injection timing determination part 13, the water injection control part 15, etc. using a dedicated hardware instead of the said computer program. Next, a procedure for realizing the control method of the internal combustion engine according to the first embodiment using the control device 10 for the internal combustion engine will be described. In the following description, please refer to FIGS.

  FIG. 6 is a flowchart illustrating a procedure of the control method of the internal combustion engine according to the first embodiment. In executing the control method for the internal combustion engine according to the first embodiment, the exhaust gas temperature determination unit 11 provided in the control device 10 for the internal combustion engine acquires the current exhaust gas temperature Te from the exhaust gas temperature sensor 46 (step S101). Then, the acquired current exhaust temperature Te is compared with a predetermined exhaust temperature upper limit value Tel (step S102). As a result, if Te ≧ Tel (step S102; Yes), it can be determined that the internal combustion engine 1 is operating at a high speed and a high load, and the emission and performance are deteriorated. For this reason, water is injected from the water injection valve 3 into the combustion chamber 1b during the overlap period, and the temperatures of the combustion chamber 1b and the exhaust are lowered. The upper limit value Tel of the exhaust temperature is a temperature at which the emission and performance of the internal combustion engine 1 are reduced by the ignition delay and the fuel increase. The upper limit value Tel differs depending on the specifications of the internal combustion engine 1, such as the presence or absence of a supercharger, but is about 900 ° C. in a spark ignition type gasoline engine that does not perform supercharging.

  The water injection amount determination unit 12 determines the water injection amount Qw based on the exhaust temperature Te, the cooling water temperature of the internal combustion engine 1 and the like (step S103). At the same time, the water injection timing determination unit 13 calculates the overlap period from the engine speed, load, and other information of the internal combustion engine 1, and determines the water injection timing θw so that water is injected during the overlap period (step S103). ). When the water injection amount Qw and the water injection timing θw are determined, the valve opening / closing timing determination unit 14 determines the increase amount of the overlap period (step S104). The increase amount of the overlap period can be changed according to the water injection amount Qw, for example.

  The water injection control unit 15 causes the water injection valve 3 to inject water W at the determined water injection amount Qw and the water injection timing θw (step S105). When Te <Tel (step S102; No), the control device 10 for the internal combustion engine monitors the exhaust temperature Te of the internal combustion engine 1.

  As mentioned above, in Example 1, water is injected from a water injection means during an overlap period. Thereby, since the combustion chamber can be cooled, the amount of intake air can be increased. As a result, the volumetric efficiency can be improved, so that a decrease in the performance of the internal combustion engine can be suppressed under operating conditions in which the combustion temperature is high, such as at high rotation and high load. Further, the water injected during the overlap period blows through the exhaust valve to the exhaust system of the internal combustion engine, so that the exhaust can be cooled. Thereby, the emission can be improved. Furthermore, since the retarding of the ignition timing and the fuel increase can be suppressed by lowering the combustion temperature and cooling the combustion chamber, it is possible to suppress the performance deterioration and the emission deterioration. The configuration disclosed in the first embodiment can be applied as appropriate in the following embodiments. In addition, since the same configuration as that of the first embodiment is provided, the same operations and effects as those of the first embodiment are obtained.

  The second embodiment has substantially the same configuration as that of the first embodiment, except that the water injection amount is adjusted according to the exhaust temperature of the internal combustion engine. Since other configurations are the same as those of the first embodiment, the description thereof is omitted and the same components are denoted by the same reference numerals. FIG. 7 is a flowchart illustrating a procedure of the control method of the internal combustion engine according to the second embodiment. The control method for the internal combustion engine according to the second embodiment can be realized by the control device 10 for the internal combustion engine according to the first embodiment.

  In executing the internal combustion engine control method according to the second embodiment, the exhaust gas temperature determination unit 11 provided in the internal combustion engine controller 10 acquires the current exhaust gas temperature Te from the exhaust gas temperature sensor 46 (step S201). Then, the acquired current exhaust temperature Te is compared with a predetermined exhaust temperature upper limit value Tel (step S202). As a result, if Te <Tel (step S202; No), the control device 10 for the internal combustion engine monitors the exhaust temperature Te of the internal combustion engine 1. If Te ≧ Tel (step S202; Yes), it can be determined that the internal combustion engine 1 is operating at a high rotation speed and a high load, and that the emission and performance are deteriorated. For this reason, water is injected from the water injection valve 3 into the combustion chamber 1b during the overlap period, and the temperatures of the combustion chamber 1b and the exhaust are lowered.

  The water injection amount determination unit 12 determines the basic water injection amount Qwb based on the exhaust temperature Te, the cooling water temperature of the internal combustion engine 1, and the like (step S203). At the same time, the water injection timing determination unit 13 calculates the overlap period from the engine speed, load, and other information of the internal combustion engine 1, and determines the water injection timing θw so that water is injected during the overlap period (step S203). ). When the basic water injection amount Qwb and the water injection timing θw are determined, the valve opening / closing timing determination unit 14 determines the increase amount of the overlap period (step S204).

  The water injection control unit 15 causes the water injection valve 3 to inject water W at the determined water injection amount Qw and the water injection timing θw (step S205). Next, the exhaust temperature determination unit 11 acquires the current exhaust temperature Ten from the exhaust temperature sensor 46 (step S206). Then, the acquired current exhaust temperature Ten is compared with the exhaust temperature Ten-1 acquired immediately before (step S207). As a result, if Ten ≦ Ten−1 (step S207; No), the exhaust temperature tends to decrease or be maintained constant, and it can be determined that the combustion state of the internal combustion engine 1 is good.

  In this case, there is still room for increasing the amount of water injection and reducing the temperature in the combustion chamber 1b of the internal combustion engine 1 and the exhaust gas temperature, thereby suppressing the deterioration of the performance and emission of the internal combustion engine 1. Therefore, the water injection amount determination unit 12 calculates the water injection increase value ΔQw (≠ 0), and sets the new water injection amount Qw as Qw + ΔQw (step S208). Then, the water injection control unit 15 causes the water injection valve 3 to inject water W with the determined water injection amount Qw (= Qw + ΔQw) (step S209). As a result, the temperature in the combustion chamber 1b of the internal combustion engine 1 and the exhaust gas temperature can be reduced, so that the performance deterioration of the internal combustion engine 1 and the operating conditions where the combustion temperature becomes high, such as at high rotation and high load, Emission deterioration can be suppressed.

  Next, the exhaust temperature determination unit 11 acquires the current exhaust temperature Ten from the exhaust temperature sensor 46 (step S210). Then, the acquired current exhaust temperature Ten is compared with a predetermined upper limit value Tel of the exhaust temperature (step S211). As a result, if Ten ≧ Tel (step S211; Yes), it can be determined that the internal combustion engine 1 is operating at a high speed and a high load, and that the emission and performance are deteriorated. For this reason, the above steps S207 to S211 are repeated. When Ten <Tel (step S211; No), the control device 10 of the internal combustion engine returns to START and monitors the exhaust temperature Te of the internal combustion engine 1.

  When Ten> Ten-1 (step S207; Yes), that is, when the exhaust temperature of the internal combustion engine 1 tends to increase, the exhaust temperature is a result of the deterioration of the combustion of the internal combustion engine 1 because the water injection amount is too large. Can be determined to be in an upward trend. Therefore, if the water injection amount is further increased, the combustion state is further deteriorated, and the performance and emission of the internal combustion engine may be deteriorated. Therefore, the water injection amount determination unit 12 sets the water injection increase value ΔQw = 0 (step S212), and sets the new water injection amount Qw to Qw + ΔQw (step S208). Then, the water injection control unit 15 causes the water injection valve 3 to inject water W with the determined water injection amount Qw (= Qw + ΔQw) (step S209). As a result, it is possible to suppress further deterioration in performance and emission of the internal combustion engine 1 under operating conditions in which the combustion temperature is high, such as during high rotation and high load.

  Next, the exhaust temperature determination unit 11 acquires the current exhaust temperature Ten from the exhaust temperature sensor 46 (step S210). Then, the acquired current exhaust temperature Ten is compared with a predetermined upper limit value Tel of the exhaust temperature (step S211). As a result, if Ten ≧ Tel (step S211; Yes), it can be determined that the internal combustion engine 1 is operating at a high speed and a high load, and that the emission and performance are deteriorated. For this reason, the above steps S207 to S211 are repeated. When Ten <Tel (step S211; No), the control device 10 for the internal combustion engine monitors the exhaust temperature Te of the internal combustion engine 1.

  As described above, according to the second embodiment, since the water injection amount is determined according to the exhaust temperature of the internal combustion engine, the water injection amount is increased within a range where the combustion does not deteriorate, and combustion is performed at the time of high rotation and high load. Under operating conditions in which the temperature increases, it is possible to suppress deterioration in performance and emission of the internal combustion engine. Moreover, since the retard of the ignition timing and the increase in fuel can be suppressed by lowering the combustion temperature and cooling the combustion chamber, it is possible to suppress the performance deterioration and the emission deterioration. The configuration disclosed in the second embodiment can be applied as appropriate in the following embodiments. In addition, since the same configuration as that of the second embodiment is provided, the same operations and effects as those of the third embodiment are obtained.

  The third embodiment has substantially the same configuration as that of the first embodiment, except that the air-fuel ratio A / F is corrected by adjusting the fuel injection amount according to the exhaust temperature of the internal combustion engine. Since other configurations are the same as those of the first embodiment, the description thereof is omitted and the same components are denoted by the same reference numerals. FIG. 8 is an explanatory diagram illustrating a control device for an internal combustion engine according to a third embodiment. The internal combustion engine control apparatus 10a according to the third embodiment has substantially the same configuration as the internal combustion engine control apparatus 10 according to the first embodiment, except that a fuel injection amount determination unit 16 is provided. The control method of the internal combustion engine according to the third embodiment can be realized by the control device 10a for the internal combustion engine. FIG. 9 is a flowchart illustrating the procedure of the control method for the internal combustion engine according to the third embodiment.

  In executing the control method for the internal combustion engine according to the third embodiment, the exhaust gas temperature determination unit 11 provided in the control device 10a for the internal combustion engine acquires the current exhaust gas temperature Te from the exhaust gas temperature sensor 46 (step S301). Then, the acquired current exhaust temperature Te is compared with a predetermined exhaust temperature upper limit value Tel (step S302). As a result, when Te <Tel (step S302; No), the control device 10 for the internal combustion engine monitors the exhaust temperature Te of the internal combustion engine 1. If Te ≧ Tel (step S302; Yes), it can be determined that the internal combustion engine 1 is operating at a high speed and a high load, and that the emission and performance are deteriorated. For this reason, water is injected from the water injection valve 3 into the combustion chamber 1b during the overlap period, and the temperatures of the combustion chamber 1b and the exhaust are lowered.

  The water injection amount determination unit 12 determines the basic water injection amount Qwb based on the exhaust temperature Te, the cooling water temperature of the internal combustion engine 1, and the like (step S303). At the same time, the water injection timing determination unit 13 calculates an overlap period from the engine speed, load, and other information of the internal combustion engine 1, and determines the water injection timing θw so that water is injected during the overlap period (step S303). ). When the basic water injection amount Qwb and the water injection timing θw are determined, the valve opening / closing timing determination unit 14 determines the increase amount of the overlap period (step S304).

  The water injection control unit 15 causes the water injection valve 3 to inject water W at the determined water injection amount Qw and the water injection timing θw (step S305). Next, the exhaust temperature determination unit 11 acquires the current exhaust temperature Ten from the exhaust temperature sensor 46 (step S306). Then, the acquired current exhaust temperature Ten is compared with the target exhaust temperature Tep (step S307). As a result, if Ten ≧ Tep (step S307; No), if the fuel is further reduced, the combustion of the internal combustion engine 1 may be deteriorated. Therefore, the control device for the internal combustion engine does not reduce the fuel injection amount. 10a continues to monitor the exhaust temperature of the internal combustion engine 1. Here, the target exhaust temperature Tep is changed depending on the specification of the internal combustion engine 1 or the like, but is smaller than the upper limit value Tel of the exhaust temperature.

  If Ten <Tep (step S307; Yes), it can be determined that the internal combustion engine 1 is operating in a good cooling state. For this reason, the fuel injection amount Qf can be reduced and the air-fuel ratio A / F can be operated on the lean side. For this reason, the fuel injection amount determination unit 16 decreases the fuel injection amount Qf, and the engine ECU 30 operates the internal combustion engine 1 with the decreased fuel injection amount (step S308). Then, the fuel reduction is continued while using water injection together until Ten ≧ Tep (step S308). When Ten ≧ Tep is satisfied (step S307; No), the fuel injection amount is not reduced and the internal combustion engine is reduced. The control device 10a continues to monitor the exhaust temperature of the internal combustion engine 1.

  As described above, according to the third embodiment, since the fuel injection amount is adjusted according to the exhaust temperature, the fuel injection amount can be reduced when the exhaust temperature is decreased by water injection. As a result, under the operating conditions in which the combustion temperature is high, such as at high rotation and high load, the deterioration of the performance and emission of the internal combustion engine 1 can be suppressed, and the fuel consumption can also be suppressed. In addition, since the same configuration as that of the third embodiment is provided, the same operations and effects as those of the third embodiment are obtained.

  As described above, the internal combustion engine and the control device for the internal combustion engine according to the present invention are useful for an internal combustion engine including a water injection unit, and are particularly suitable for suppressing deterioration of emissions and deterioration of performance.

1 is a cross-sectional view relating to one cylinder included in an internal combustion engine according to Embodiment 1. FIG. It is explanatory drawing which shows the water supply system to a water injection valve. It is sectional drawing which shows the structural example of a water injection valve. It is explanatory drawing which shows the time of water injection. It is explanatory drawing which shows the time of water injection. It is explanatory drawing which shows an example of the mechanism which changes the opening / closing timing of an intake valve and an exhaust valve. 1 is an explanatory diagram illustrating a configuration of a control device for an internal combustion engine according to Embodiment 1. FIG. 3 is a flowchart illustrating a procedure of a control method for the internal combustion engine according to the first embodiment. 7 is a flowchart illustrating a procedure of a control method for an internal combustion engine according to a second embodiment. FIG. 6 is an explanatory diagram illustrating a control device for an internal combustion engine according to a third embodiment. 7 is a flowchart illustrating a procedure of a control method for an internal combustion engine according to a third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 1b Combustion chamber 1h Cylinder head 1s Cylinder 2 Port injection valve 3 Water injection valve 10, 10a Control apparatus of an internal combustion engine 11 Exhaust temperature determination part 12 Water injection amount determination part 13 Water injection timing determination part 14 Valve opening / closing timing determination part 15 Water Injection Control Unit 16 Fuel Injection Amount Determination Unit 30 Engine ECU
50 Water tank 60 Valve opening / closing timing control mechanism

Claims (10)

A reciprocating internal combustion engine comprising an intake valve and an exhaust valve,
An internal combustion engine comprising water injection means for supplying water to a combustion chamber of the internal combustion engine by injecting water during a period in which the timing when the intake valve opens and the timing when the exhaust valve closes .   2. The internal combustion engine according to claim 1, wherein water is injected from the water injection unit when the exhaust temperature of the internal combustion engine is equal to or higher than a predetermined upper limit value of the exhaust temperature.   The internal combustion engine according to claim 1, wherein the overlap period is increased during water injection by the water injection unit.   The internal combustion engine according to any one of claims 1 to 3, wherein the water injection amount by the water injection means is changed based on the exhaust temperature.   The internal combustion engine according to any one of claims 1 to 3, wherein a fuel injection amount for the internal combustion engine is changed based on the exhaust temperature. A reciprocating internal combustion engine comprising an intake valve, an exhaust valve, and water injection means for supplying water to the combustion chamber;
An exhaust temperature determination unit for determining an exhaust temperature of the internal combustion engine;
When the exhaust temperature is equal to or higher than a predetermined upper limit value of the exhaust temperature, the water injection means injects water so that the water injection means injects water during a period in which the intake valve opens and the exhaust valve closes. A water injection timing determining unit for determining the water injection timing of the means;
A control apparatus for an internal combustion engine, comprising:   And a valve opening / closing timing determining unit that determines at least one of a timing for opening the intake valve and a timing for closing the exhaust valve so as to increase the overlap period during water injection by the water injection means. The control device for an internal combustion engine according to claim 6.   8. The internal combustion engine according to claim 6, further comprising a water injection amount determination unit that increases the injection amount of the water until the exhaust temperature determination unit determines that the exhaust temperature starts to increase. Control device.   9. The internal combustion engine according to claim 8, further comprising a water injection amount determination unit that stops increasing the water injection amount when the exhaust temperature determination unit determines that the exhaust temperature tends to increase. Control device.   7. A fuel injection amount determination unit that reduces a fuel injection amount for the internal combustion engine when the exhaust temperature determination unit determines that the exhaust temperature is lower than a predetermined target temperature. Or a control device for an internal combustion engine according to 7;

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