JP2019135386A - Internal combustion engine - Google Patents

Abstract

To efficiently suppress turbo lag of a reciprocation-type internal combustion engine including a turbo supercharger.SOLUTION: A reciprocation-type internal combustion engine (1) including a turbo supercharger (9), further includes a water injection nozzle (8) opposed to a back side of an opened exhaust valve (7) and injecting water from the inside of a combustion chamber (40), and control means (10) operating the water injection nozzle under acceleration request. In a preferable embodiment, a plurality of exhaust valves (7) are disposed for each cylinder, the water injection nozzle (8) has a plurality of nozzle holes opposed to a back side of each exhaust valve, and one valve element for opening and closing the plurality of nozzle holes. Another preferable embodiment includes a plurality of cylinders (3), and a variable valve mechanism (50) for controlling an opening/closing timing of the exhaust valve of each cylinder. The control means includes a function for opening the exhaust valve (7) of the cylinder in an exhaust stroke and an expansion stroke under acceleration request, and operating the water injection nozzle (8) of each cylinder.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an internal combustion engine, and more particularly to a reciprocating internal combustion engine equipped with a turbocharger.

  A reciprocating internal combustion engine equipped with a turbocharger excels in energy utilization efficiency, but delays until a sufficient boost pressure is obtained during sudden acceleration from low speed or reacceleration after deceleration (turbo lag) Occurs. Patent Document 1 discloses that water is injected into a combustion chamber or an exhaust passage and evaporated to increase the turbine flow rate and suppress turbo lag.

JP 2008-8223 A

  However, water injection into the combustion chamber may cause moisture to adhere to the cylinder and dilute oil if vaporization is insufficient, and exhaust gas will deteriorate if combustion retard is used for vaporization. There's a problem. Furthermore, water injection at the exhaust port requires a water injection nozzle for each exhaust port, and there is a problem that the structure becomes complicated.

  The present invention has been made in view of the above points of the prior art, and an object thereof is to efficiently suppress the turbo lag of a reciprocating internal combustion engine equipped with a turbocharger.

In order to solve the above problems, the present invention provides:
In a reciprocating internal combustion engine equipped with a turbocharger,
A water injection nozzle for injecting water from the combustion chamber facing the back side of the opened exhaust valve;
Control means for operating the water injection nozzle when acceleration is requested is provided.

  In the present invention, as described above, water is injected from the combustion chamber so as to face the back side of the exhaust valve that is opened when acceleration is requested, so that the vaporization of water is promoted by the exhaust valve that is hotter than the exhaust port, and the turbo lag is effective. Can be reduced. Further, it is possible to prevent moisture from adhering to the cylinder and the accompanying oil dilution, and the exhaust gas is not deteriorated because the combustion retardation is not used.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram (a) showing an internal combustion engine according to an embodiment of the present invention, and a BB sectional view (b) thereof. It is a time chart which shows control of the internal-combustion engine concerning the embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
As shown in the schematic configuration diagram of FIG. 1 (a), an internal combustion engine 1 according to an embodiment of the present invention is a reciprocating internal combustion engine including a piston 4 accommodated in a cylinder 3 so as to be reciprocally slidable. 4 is connected to the crack shaft 2 via the connecting rod 24, and the reciprocating linear motion of the piston 4 is converted into the rotational motion of the crankshaft 2.

  A cylinder head 30 that defines a combustion chamber 40 between the piston 3 and the piston 4 is provided at an upper portion of the cylinder 3, and an ignition plug 31 is provided at the center of the cylinder 3 so as to face the combustion chamber 40. An intake port 60 and an exhaust port 70 communicating with the combustion chamber 40 are defined in the cylinder head 30. An intake valve 6 for opening and closing the intake port 60 and an exhaust valve 7 for opening and closing the exhaust port 70 are defined. Is supported to be movable up and down.

  As shown in FIG. 1B, the internal combustion engine 1 of the present embodiment has a four-valve configuration in which each cylinder includes two intake valves 6 (intake ports 60) and two exhaust valves 7 (exhaust ports 70). There may be other than this. As shown schematically in FIG. 1 (a) only on the exhaust side, the intake valve 6 and the exhaust valve 7 are given basic opening / closing operations by the cam 5, and the opening / closing timings of the intake valve 6 and the exhaust valve 7 are individually controlled by the variable valve mechanism 50 (VVT). Be controlled.

  As the variable valve mechanism 50, a hydraulic actuator or electromagnetic actuator is interposed so that the exhaust valve 7 can be opened and closed at a position different from the phase of the cam 5, or a hydraulic actuator or electromagnetic actuator is used instead of the cam 5. A type that opens and closes can be used, and as described later, a type having a function of opening the exhaust valve 7 early in an expansion stroke before a normal exhaust stroke in a predetermined cylinder can be used.

  Although the fuel injector 61 is provided in the intake port 60, a direct injection injector that directly injects fuel into the combustion chamber 40 may be used. An exhaust temperature sensor 71 is provided in the exhaust port 70, and a turbocharger 9 (exhaust turbine) is provided in the exhaust path downstream thereof. The turbocharger 9 performs supercharging by driving a compressor in the intake path by an exhaust turbine that is rotated by the energy of exhaust gas discharged from the engine.

  The internal combustion engine 1 includes an engine control device 10 (ECU) for optimizing the operation state. The engine control device 10 is a computer for performing engine control based on an input signal from a sensor that detects each state value that reflects the operation state, and includes a CPU that performs arithmetic processing, a control program, setting data, and the like. A ROM for storing data, a RAM for reading control programs and setting data, and storing dynamic data and calculation processing results, an input / output port, and the like are provided.

  The engine control device 10 detects a piston position and an engine speed based on input signals from the crank angle sensor 21 and the cam angle sensor 51, and takes an intake air amount sensor, an intake air temperature sensor, a water temperature sensor, an air-fuel ratio sensor, an accelerator opening. By determining the fuel injection amount, ignition timing, and valve opening / closing timing based on the detection value of the degree sensor (load request), and outputting a control signal to the fuel injector 61, spark plug 31, variable valve mechanism 50, etc. The operating state of the internal combustion engine 1 is optimized.

  The internal combustion engine 1 having the basic configuration as described above faces the back side (the stem side, the exhaust port 70 side) of the opened exhaust valve 7 as shown in FIG. A water injection nozzle 8 (water injector) for performing water injection is provided in the combustion chamber 40.

  The water injection nozzle 8 has a built-in needle valve that is opened and closed by a solenoid or a piezo. The needle valve is opened and closed by a control signal from the engine control device 10 and is pressurized by the water pump 81 from the water tank 80. The supplied water is jetted. In the open state of the exhaust valve 7, a predetermined amount of water injected to the back side of the exhaust valve 7 is vaporized by the residual heat of the exhaust valve 7, and is sent to the turbocharger 9 (exhaust turbine) together with the exhaust gas. Driving the turbocharger 9 is promoted by increasing the turbine flow rate.

  The water injection from the water injection nozzle 8 models the in-cylinder state immediately before the acceleration request based on the engine speed at the time of the acceleration request, the exhaust gas temperature detected by the exhaust temperature sensor 71, the fuel injection amount, and the ignition timing. Thus, the temperature of the exhaust valve 7 and the maximum latent heat of vaporization are estimated, and water that can be completely evaporated when the exhaust valve 7 is reached is injected. The injection amount is controlled by the time (duty ratio) and the number of times of continuous injection or intermittent injection.

  The water injection nozzle 8 in the present embodiment is disposed on the cylinder head 30 at the uppermost side of the combustion chamber 40 of each cylinder, and faces the two exhaust valves 7 (exhaust ports 70) as shown in FIG. 1 (b). The two nozzle holes are formed so that water vapor can be supplied to both of the two exhaust ports 70 simultaneously by the operation of one needle valve.

  The water tank 80 and the water pump 81 are provided in common to each cylinder of the internal combustion engine 1, and a common pressure accumulating unit is provided between the water pump 81 and the water injection nozzle 8 of each cylinder. The water pump 81 does not need to be driven at all times, and a predetermined pressure is stored in the pressure accumulator in a situation where the water injection assist to the turbocharger 9 is necessary from the operating state of the internal combustion engine 1, for example, at low speed or during deceleration. It is driven in a limited manner so as to obtain a water pressure of 2.

  Next, the control of the internal combustion engine 1 based on the above embodiment will be described with reference to the time chart of FIG.

  As shown in FIG. 2, when the accelerator pedal opening (re-acceleration signal) exceeds a predetermined threshold value when the accelerator is turned on from the accelerator-off (fuel cut-off), the following control is performed according to the stroke of each cylinder. Is activated.

(1) Exhaust stroke Since the exhaust valve 7 is opened in the first cylinder in the exhaust stroke, water injection is immediately performed by the water injection nozzle 8 of the cylinder. Water injection is continued while the valve lift is above a predetermined level before the exhaust valve 7 is closed, and is stopped before the start of the intake stroke.

(2) Intake stroke In the No. 2 cylinder in the intake stroke, fuel is injected when the accelerator is turned on, and the normal combustion to expansion stroke can be shifted. Therefore, the intake stroke is continued without performing water injection.

(3) Expansion stroke In the third cylinder in the expansion stroke, the exhaust valve 7 is opened, and water injection is performed by the water injection nozzle 8 of the cylinder. Water injection is continued even in the exhaust stroke in which the piston 4 starts to rise, and is performed while the valve lift is higher than a predetermined level before the exhaust valve 7 is closed, and is stopped before the start of the intake stroke.

(4) Compression stroke Even in the fourth cylinder in the compression stroke, the exhaust valve 7 is opened, and water injection is performed by the water injection nozzle 8 of the cylinder. Water injection is continued in the subsequent expansion stroke to exhaust stroke, and is stopped before the start of the intake stroke in the same manner as described above.

  The detection of the exhaust gas temperature and the estimation of the temperature of the exhaust valve 7 are continued during the control period, and when the estimated temperature of the exhaust valve reaches a threshold value (lower limit value), the water injection of the cylinder is stopped, Ensure that the exhaust valve temperature is maintained above the threshold.

  FIG. 2 shows a case where the water injection started in the compression stroke in the No. 4 cylinder is stopped in the middle of the exhaust stroke, but the exhaust valve temperature is maintained above the threshold when the engine temperature is high. In this case, water injection is continued until just before the intake stroke. Further, before the exhaust valve temperature decreases to the threshold value, the water injection amount may be narrowed down in the expansion stroke (unburned) or the water injection may be stopped, and the water injection may be continued in the exhaust stroke.

  In the above control, the case of re-acceleration from the fuel cut-off has been described. However, if fuel is not cut off (even if it is a small amount) in the low-rotation operation state before the acceleration request, an acceleration request is made. In the cylinder (4th cylinder) that is sometimes in the compression stroke, the above control may not be applied, and the combustion cycle may be immediately started.

  Further, in the normal combustion cycle after the above-described control of one cycle is completed, water injection may be performed in the cylinders in the exhaust stroke to drive the turbocharger 9. Even when the present invention is applied to an internal combustion engine that does not have a variable valve mechanism that can open the exhaust valve 7 other than in the exhaust stroke, the turbo lag is performed by sequentially performing water injection on the cylinders that have entered the exhaust stroke after the acceleration request. Can contribute to suppression.

  As described above, the control for each stroke in each cylinder is performed in such a way that a plurality of control routines optimized according to the piston position at the time of acceleration request, the engine speed, the exhaust gas temperature, etc. are stored in the engine control device 10 in advance. Therefore, it is preferable that the optimum control routine for the situation is immediately selected and executed when acceleration is requested.

  In the above embodiment, the exhaust valve temperature is estimated for each cylinder. However, the exhaust valve temperature of all the cylinders may be estimated by an exhaust gas temperature sensor arranged downstream from the exhaust pipe merging portion. In this case, the injection amount is set based on the exhaust valve temperature of the cylinder (the fourth cylinder in FIG. 2) in which the longest water injection is performed.

  Moreover, although the case where the water injection nozzle 8 was arrange | positioned at the exhaust port 7 side was shown in the said embodiment, the water injection nozzle 8 is opposed to other positions, for example, the back side of the opened exhaust valve 7. It can also be disposed on the side of the combustion chamber on the intake port 60 side.

  In the above embodiment, the case where the present invention is implemented in a four-cylinder engine has been described. However, the present invention can be implemented in an internal combustion engine having any number of cylinders.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, Based on the technical idea of this invention, various deformation | transformation and a change are further possible.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Crankshaft 3 Cylinder 4 Piston 5 Cam 6 Intake valve 7 Exhaust valve 8 Water injection nozzle 9 Turbo supercharger 10 Engine control apparatus (ECU)
21 Crank angle sensor 24 Connecting rod 30 Cylinder head 31 Spark plug 40 Combustion chamber 50 Variable valve mechanism (VVT)
51 Cam Angle Sensor 60 Intake Port 61 Fuel Injector 70 Exhaust Port 71 Exhaust Temperature Sensor 80 Water Tank 81 Water Pump

Claims (4)

In a reciprocating internal combustion engine equipped with a turbocharger,
A water injection nozzle for injecting water from the combustion chamber facing the back side of the opened exhaust valve;
Control means for activating the water injection nozzle at the time of an acceleration request;
An internal combustion engine comprising:   A plurality of exhaust valves are provided in a cylinder, and the water injection nozzle has a plurality of nozzle holes facing the back side of each of the exhaust valves, and a single valve element that opens and closes the plurality of nozzle holes. The internal combustion engine according to claim 1. A plurality of cylinders, and a variable valve mechanism for controlling the opening and closing timing of the exhaust valve of each cylinder,
3. The internal combustion engine according to claim 1, wherein the control means includes a function of opening an exhaust valve of a cylinder other than the intake stroke at a time of an acceleration request and operating a water injection nozzle of each cylinder.   The internal combustion engine according to claim 3, wherein the control means includes a function of stopping a water injection nozzle of the cylinder when an exhaust gas temperature falls below a predetermined value during the water injection.

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