JP2023150515A - Controller of internal combustion engine - Google Patents

Abstract

To contribute to further reducing mechanical loss in an internal combustion engine comprising a plurality of suction valves for each cylinder.SOLUTION: An internal combustion engine is configured such that a plurality of suction valves is provided in one cylinder, and a maximum lift amount of one suction valve or timing at which the maximum lift amount is taken is made different from a maximum lift amount of another suction valve or timing at which the maximum lift amount is taken. Then, the internal combustion engine is configured such that a spring constant of a spring that elastically biases a valve body of the one suction valve in a closing direction and a spring constant of a spring that elastically biases the valve body of the other suction valve in the closing direction are set to different values.SELECTED DRAWING: Figure 3

Description

The present invention relates to an internal combustion engine mounted on a vehicle or the like as a power source.

As a four-stroke reciprocating engine, a so-called multi-valve engine in which each cylinder is provided with a plurality of intake ports and intake valves is known (see, for example, the following patent documents).

Japanese Patent Application Publication No. 2016-044723

One approach to further improve the output and fuel efficiency of internal combustion engines is to reduce the mechanical loss associated with opening and closing intake and exhaust valves of cylinders. In a typical multi-valve engine, multiple valves mounted in one cylinder are simultaneously pressed by the same number of cam lobes to open them. Therefore, the sum of the reaction forces that the camshaft receives from the valve springs that elastically bias the valve bodies of each valve in the closing direction increases, and the friction between the tappet (or valve lifter) and the cam lobe also increases.

By reducing the valve lift amount (valve opening amount) or reducing the spring constant of the valve spring, it is possible to reduce the reaction force applied to the camshaft and reduce the friction between the tappet and cam lobe. be. However, reducing the valve lift amount not only reduces the amount of intake air flowing into the cylinder, but also weakens the in-cylinder flow, especially the tumble flow, which is important for mixing air and fuel well, which reduces the output of the internal combustion engine and fuel efficiency. and have a negative impact on emissions. Furthermore, simply reducing the spring constant of the valve spring causes another problem in that resonance is more likely to occur.

An objective of the present invention is to contribute to further reduction of mechanical loss in an internal combustion engine having a plurality of intake valves for each cylinder.

In the present invention, a plurality of intake valves are provided in one cylinder, and the timing at which one of the intake valves takes the maximum lift amount or the maximum lift amount, and the timing when the other intake valve takes the maximum lift amount or maximum lift amount are determined. Different internal combustion engines were constructed.

More preferably, the spring constant of the spring that elastically biases the valve body of the one intake valve in the closing direction and the spring constant of the spring that elastically biases the valve body of the other intake valve in the direction of closing are set to be different. Set to

According to the present invention, it is possible to contribute to further reduction of mechanical loss in an internal combustion engine including a plurality of intake valves for each cylinder.

1 is a diagram showing a schematic configuration of a vehicle internal combustion engine and a control device according to an embodiment of the present invention. FIG. 3 is a perspective view showing an intake valve and an intake camshaft of the internal combustion engine of the same embodiment. FIG. 3 is a timing chart illustrating the relationship between the lift amount of one of the plurality of intake valves included in one cylinder of the internal combustion engine of the same embodiment and that of the other. FIG. 3 is a timing chart illustrating the relationship between the lift amount of one of the plurality of intake valves included in one cylinder of the internal combustion engine of the same embodiment and that of the other. FIG. 3 is a timing chart illustrating the relationship between the lift amount of one of the plurality of intake valves included in one cylinder of the internal combustion engine of the same embodiment and that of the other.

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an overview of a vehicle internal combustion engine in this embodiment. The internal combustion engine of this embodiment is a port injection type four-stroke spark ignition reciprocating engine, and includes a plurality of cylinders 1 (for example, three cylinders, one of which is shown in FIG. 1). In the vicinity of the intake port of each cylinder 1, an injector 11 is provided for each cylinder 1 to inject fuel toward the intake port. Further, a spark plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1. The spark plug 12 causes a spark discharge between a center electrode and a ground electrode upon application of an induced voltage generated in an ignition coil. The ignition coil is integrally built into the coil case together with the igniter, which is a semiconductor switching element.

The intake passage 3 for supplying intake air takes in air from the outside and guides it to the intake port of each cylinder 1. On the intake passage 3, an air cleaner 31, an electronic throttle valve 32 which is an intake throttle valve, a surge tank 33, and an intake manifold 34 are arranged in this order from upstream.

The exhaust passage 4 for discharging exhaust gas guides the exhaust gas generated as a result of burning fuel in the cylinders 1 from the exhaust port of each cylinder 1 to the outside. An exhaust manifold 42 and a three-way catalyst 41 for exhaust purification are arranged on the exhaust passage 4.

The exhaust gas recirculation device 2 includes an external EGR passage 21 that communicates the exhaust passage 4 and the intake passage 3, an EGR cooler 22 provided on the EGR passage 21, and an EGR passage 21 that opens and closes the EGR passage 21. The element includes an EGR valve 23 that controls the flow rate of EGR gas flowing through the passage 21. The entrance of the EGR passage 21 is connected to a predetermined location downstream of the catalyst 41 in the exhaust passage 4 . The outlet of the EGR passage 21 is connected to a predetermined location downstream of the throttle valve 32 in the intake passage 3 (in particular, the surge tank 33 or the intake manifold 34).

In this embodiment, an electronic control unit 0 that controls the operation of the internal combustion engine is a microcomputer system that includes a processor, a memory, an input interface, an output interface, and the like. The ECU0 may include a plurality of ECUs or controllers connected to each other so as to be communicable via a telecommunication line such as a CAN (Controller Area Network).

The input interface of ECU0 includes a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle, and a crank angle signal b output from a crank angle sensor that detects the rotation angle and engine rotation speed of the crankshaft of the internal combustion engine. , an accelerator opening signal c output from a sensor that detects the amount of depression of the accelerator pedal by the driver (accelerator opening, in other words, required engine torque or engine load factor); An intake temperature/intake pressure signal d output from a temperature/pressure sensor that detects the intake air temperature and intake pressure downstream of the valve 32, particularly in the surge tank 33 or intake manifold 34), and a water temperature that detects the cooling water temperature of the internal combustion engine. A cooling water temperature signal e outputted from a sensor, an acceleration signal f outputted from an acceleration sensor that detects the acceleration of the vehicle or the gradient of the road surface on which the vehicle is currently located, and multiple cam angles of the intake camshaft 13 of the internal combustion engine. A cam angle signal g outputted from a cam angle sensor, a signal h outputted from a switch operated by the driver, a selector lever (a position sensor attached thereto), etc. are input.

From the output interface of the ECU0, an ignition signal i is sent to the igniter attached to the spark plug 12, a fuel injection signal j is sent to the injector 11, an opening operation signal k is sent to the throttle valve 32, and an opening signal is sent to the EGR valve 23. outputs an operation signal l, etc.

The processor of ECU0 interprets and executes programs stored in memory, calculates operating parameters, and controls the operation of the internal combustion engine. ECU0 acquires various information a, b, c, d, e, f, g, h necessary for control via the input interface, learns the engine rotation speed, and detects the air (fresh air) taken into cylinder 1. ) Estimate the amount. Then, the required fuel injection amount commensurate with the intake air amount (to achieve the stoichiometric air-fuel ratio or a target air-fuel ratio close to it), fuel injection timing (including the number of fuel injections for one combustion), fuel injection pressure, Various operating parameters such as ignition timing (including the number of ignitions for one combustion), required EGR rate (or EGR gas amount, EGR gas partial pressure), etc. are determined. ECU0 applies various control signals i, j, k, l corresponding to operating parameters via an output interface.

As shown in FIG. 2, the internal combustion engine of this embodiment includes a plurality of intake ports and intake valves 14 for each cylinder 1. Poppet valve bodies 141 and 142 that open and close each intake port are elastically biased by valve springs 143 and 144, respectively, in the direction of closing, that is, in the direction of seating on the valve seat. A camshaft 13 that drives the intake valves 14 to open and close is provided with protruding cam lobes 131 and 132 of the same number as the intake valves 14 for each cylinder 1. When each of the cam lobes 131, 132 contacts and presses the valve tappet, the valve bodies 141, 142 of the intake valve 14 are pushed down against the elastic urging force of the springs 143, 144, and the valve bodies 141, 142 are pressed against the valve seat. In other words, the intake valve 14 opens.

In this embodiment, the profile of the first cam lobe 131 and the profile of the second cam lobe 131 that respectively drive the valve bodies 141 and 142 of the plurality of intake valves 14 of one cylinder 1 are made different. In other words, when viewed from the axial direction of the camshaft 13 (a direction parallel to the direction in which the central axis of the camshaft 13 extends), the first cam lobe 131 and the second cam lobe 132 do not completely overlap.

In the example shown in FIG. 3, the center angle of the first cam lobe 131 that drives the first valve body 141 and the center angle of the second cam lobe 132 that drives the second valve body 142 are set along the rotation direction of the camshaft 13. By shifting, the timing at which the lift amount (represented by the broken line) of the second valve element 142 reaches its maximum can be changed by up to 5 times in terms of crank angle from the timing at which the lift amount (represented by the solid line) of the first valve element 141 reaches its maximum. °CA is delayed. As a result, the maximum value of the reaction force acting on the camshaft 13 that tries to push open both the valve bodies 141 and 142 of the intake valve 14 is reduced. Furthermore, the spring constant of the spring 144 that biases the second valve body 142 is set to be smaller than the spring constant of the spring 143 that biases the first valve body 141, thereby suppressing the occurrence of resonance and allowing the valve tappet to Friction between the cam lobe 132 and the cam lobe 132 can be reduced.

In the example shown in FIG. 4, the second cam lobe 132 that drives the second valve body 142 is made lower than the first cam lobe 131 that drives the first valve body 141, and the lift amount of the second valve body 142 (broken line The maximum value of the lift amount (represented by a solid line) of the first valve body 141 is made smaller than the maximum value of the lift amount (represented by a solid line) of the first valve body 141. The difference between the two shall be 2 mm or less. As a result, the maximum value of the reaction force acting on the camshaft 13 that tries to push open both the valve bodies 141 and 142 of the intake valve 14 is reduced. Furthermore, the spring constant of the spring 144 that biases the second valve body 142 is set to be smaller than the spring constant of the spring 143 that biases the first valve body 141, thereby suppressing the occurrence of resonance and allowing the valve tappet to Friction between the cam lobe 132 and the cam lobe 132 can be reduced.

The example shown in FIG. 5 is a combination of the example shown in FIG. 3 and the example shown in FIG. Again, the maximum value of the reaction force acting on the camshaft 13 that tries to push open both valve bodies 141 and 142 of the intake valve 14 is reduced. Furthermore, the spring constant of the spring 144 that biases the second valve body 142 is set to be smaller than the spring constant of the spring 143 that biases the first valve body 141, thereby suppressing the occurrence of resonance and allowing the valve tappet to Friction between the cam lobe 132 and the cam lobe 132 can be reduced.

Note that when the injectors 11 are individually installed in a plurality of intake ports connected to one cylinder 1, the amount of fuel injected from the injector 11 facing the intake port opened and closed by the first valve body 141 is It is also conceivable to further reduce the amount of fuel injected from the injector 11 facing the intake port where the two valve bodies 142 open and close.

According to the present embodiment, the necessary and sufficient amount of intake air flowing into the cylinder 1 is ensured, and while the in-cylinder flow, particularly the tumble flow, is effectively generated, the mechanical loss accompanying the opening/closing drive of the intake valve 14 is further reduced. can be achieved.

The present invention is not limited to the embodiments detailed above. The specific configuration of each part can be modified in various ways without departing from the spirit of the present invention.

0...Control unit (ECU)
1...Cylinder 13...Intake camshaft 131, 132...Cam lobe 14...Valve 141, 142...Valve body 143, 144...Valve spring

Claims (2)

Multiple intake valves are provided in one cylinder,
An internal combustion engine in which the maximum lift amount or the timing at which one of the intake valves takes the maximum lift amount is different from the maximum lift amount or the timing at which the other intake valve takes the maximum lift amount. 2. The spring constant of the spring that elastically biases the valve body of the one intake valve in the closing direction is different from the spring constant of the spring that elastically biases the valve body of the other intake valve in the closing direction. internal combustion engine.

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