JP4347199B2 - 4-cycle engine with internal EGR system - Google Patents

Description

  The present invention is mainly applied to a four-cycle diesel engine and a four-cycle gas engine. When the intake valve is opened, the exhaust valve is lifted so that a part of the exhaust gas in the exhaust passage is recirculated into the combustion chamber and mixed into the intake air. It relates to a 4-cycle engine with an internal EGR system.

In a four-cycle diesel engine, a four-cycle gas engine, and the like, when the intake valve is opened, a part of the combustion gas in the combustion chamber is sent to the intake passage, mixed with the intake air, and the intake air mixed with EGR gas is returned to the combustion chamber. An engine with an internal EGR (exhaust gas recirculation) system is provided.
One of the technologies related to an engine equipped with such an internal EGR system is a technology provided in Patent Document 1 (Japanese Patent Laid-Open No. 7-133726).

  In such a technique, an intake control valve that opens and closes the intake passage to change the intake passage area is installed in the intake passage, and the intake valve is opened before the intake control valve immediately before the end of the exhaust stroke, resulting in a negative pressure. The combustion gas (EGR gas) is pushed into the intake passage by the rise of the piston, the intake air mixed with EGR gas is recirculated into the combustion chamber during the intake stroke, and the intake control valve is related to the opening / closing timing of the intake valve and the engine Open / close control is performed according to engine operating conditions such as load and engine speed, and the pressure (negative pressure) between the intake control valve and the intake valve is controlled to control the internal EGR amount to a desired value.

JP-A-7-133726

  A four-cycle diesel engine equipped with an internal EGR system that feeds a portion of the combustion gas in the combustion chamber into the intake passage when the intake valve is opened, and mixes the intake gas with EGR gas back into the combustion chamber. In a gas engine, the internal EGR amount and internal EGR timing can be freely controlled in accordance with engine operating conditions such as engine load, engine speed, etc., and the intake valve open state, thereby reducing engine performance. Therefore, it is necessary to reduce the amount of NOx (nitrogen oxide) generation.

  However, in the technique disclosed in Patent Document 1 (Japanese Patent Application Laid-Open No. 7-133726), intake control is performed during a period when the intake valve is open before the exhaust valve is closed, that is, when the exhaust valve and the intake valve overlap. Since the valve opening / closing timing is controlled, the intake control valve opening / closing control is uniquely determined by the overlap timing of the exhaust valve and the intake valve, and the intake control valve opening / closing control is controlled with a degree of freedom. Therefore, the internal EGR amount and internal EGR timing can be freely adjusted according to the engine operating conditions and the intake valve open state, and the NOx (nitrogen oxide) generation amount can be reduced without degrading the engine performance. It is difficult to control.

In addition, as in Patent Document 1 (Japanese Patent Laid-Open No. 7-133726), when the intake valve is opened, a part of the combustion gas in the combustion chamber is sent to the intake passage and mixed with the intake air to mix the EGR gas. In addition to the internal EGR system that recirculates gas to the combustion chamber, the overlap period between the exhaust valve and the intake valve is set longer by continuing the small lift of the exhaust valve even in the initial stage of opening of the intake valve. There has also been proposed a four-cycle engine having an exhaust passage recirculation internal EGR system in which a part of exhaust gas is recirculated into the combustion chamber and mixed with intake air.
However, even in such an exhaust passage recirculation type internal EGR system, since the overlap period between the exhaust valve and the intake valve is controlled, the EGR from the exhaust passage depends on the overlap timing of the exhaust valve and the intake valve. It is determined uniquely, and it is difficult to control the internal EGR amount and the internal EGR timing to appropriate values that can reduce the NOx (nitrogen oxide) generation amount without degrading the engine performance.

  In view of the problems of the prior art, the present invention freely corresponds to the internal EGR amount and the internal EGR timing in accordance with the engine operating conditions and the open state of the exhaust valve, and NOx (nitrogen oxide) without deteriorating the engine performance. An object of the present invention is to provide a 4-cycle engine equipped with an internal EGR system that can control the generation amount to an appropriate value that can be reduced.

The present invention achieves such an object. An internal EGR system (exhaust gas recirculation) that lifts the exhaust valve when the intake valve is opened to recirculate a part of the exhaust gas in the exhaust passage into the combustion chamber and mix it with the intake air. In the four-cycle engine equipped with a system), the exhaust valve is divided into two lifts: a main lift including the exhaust valve being fully opened and a sub-lift of a lift that is later than the start of opening the intake valve and smaller than the main lift. The exhaust passage is configured to open, and an exhaust control valve that opens and closes the exhaust passage to change the exhaust passage area when the exhaust valve is sublifted is installed in the exhaust passage, and the exhaust control valve is opened and closed during the sublift. the recirculation amount of exhaust gas fed from the exhaust passage into the combustion chamber is configured to adjust (EGR amount), for driving the exhaust control valve by A gas control valve drive device, an engine speed detector, an engine load detector, an engine speed detection value from the engine speed detector, and an engine load detection value from the engine load detector. A controller for controlling the operation of the exhaust control valve drive device based on an engine operation condition detection value of a rotational speed detection value and an engine load detection value, and the controller drives the exhaust control valve based on the engine operation condition detection value. The exhaust control valve is configured to change the opening / closing timing of the exhaust control valve by changing the opening degree of the exhaust control valve through a device, and the operation of the intake valve gap sensor or the exhaust valve that detects the operation of the intake valve is detected. wherein the configuration to be to change the closing timing of the basis of the operation signal from the exhaust valve gap sensor the exhaust control valve

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Also, in this invention, the exhaust control valve opening / closing control means by the controller is configured to keep the exhaust control valve opening degree constant via the exhaust control valve drive device based on the engine operating condition detection value. It is configured to change the opening / closing timing of the.

According to the present invention, to open in two lifts form the main lift and also delayed from the time the start of the opening of the intake valves and the smaller lift than the main lift Saburifuto including fully open exhaust valves and the exhaust valves And an exhaust control valve that opens and closes the exhaust passage to change the exhaust passage area when the exhaust valve is sublifted, and the controller opens the intake valve and opens the exhaust valve when the exhaust valve is sublifted. When the exhaust control valve is opened under the control of the internal EGR, a part of the exhaust gas in the exhaust passage is fed into the combustion chamber through the exhaust control valve and the exhaust valve in the sub-lift state and mixed with the intake air, thereby causing internal EGR. Is made.

Further, the opening degree or opening / closing timing of the exhaust control valve at the time of sub-lift of the exhaust valve is determined by the controller, specifically, the exhaust control via the exhaust control valve drive device based on the detected engine operating condition as described above. This means is configured to change the opening / closing timing of the exhaust control valve while keeping the valve opening constant, and is controlled based on engine operating condition detection values such as an engine speed detection value and an engine load detection value.
Therefore, when the engine requiring internal EGR is started and operated at a low load, the controller performs control to open the exhaust control valve and connect the exhaust passage and the combustion chamber in the intake stroke to perform internal EGR. The internal EGR can be stopped by closing the exhaust control valve during medium and high load operation.

Therefore, according to this invention, the exhaust control valve is controlled to open and close based on the engine operating condition detection values such as the engine speed detection value and the engine load detection value during the sub-lift of the exhaust valve. The EGR is not uniquely determined by the overlap timing of the exhaust valve and the intake valve, but opens and closes the exhaust control valve according to the engine operating condition in relation to the sublift at the time of the sublift set independently from the main lift of the exhaust valve Therefore, the internal EGR amount and the internal EGR timing can be freely controlled regardless of the overlap timing of the exhaust valve and the intake valve.
As a result, the internal EGR amount and the internal EGR timing can be freely controlled in combination with the sub-lift set to the exhaust valve and the opening / closing control of the exhaust control valve, thereby reducing NOx (nitrogen oxides) without degrading the engine performance. ) It can be accurately controlled to an appropriate value that can reduce the generation amount.

  Further, as in Patent Document 1 (Japanese Patent Laid-Open No. 7-133726), when the high-temperature internal EGR gas from the combustion chamber is passed through the intake control valve provided in the intake passage, the intake control valve has a low temperature. Although it is alternately exposed to the intake air and the high-temperature internal EGR gas, the thermal stress of the intake control valve due to the temperature difference increases, but according to this invention, the internal EGR gas is not put on the intake side, and Since the exhaust control valve contacts only the high-temperature exhaust gas, the thermal stress due to the temperature difference of the exhaust control valve is reduced, and the durability is higher than that of the intake control valve.

The present invention further includes an intake valve gap sensor that detects the operation of the intake valve and inputs the detected intake valve to the controller, and the controller controls the opening / closing timing of the exhaust control valve based on an intake valve operation signal from the intake valve gap sensor. It is configured to change.
The present invention further includes an exhaust valve gap sensor that detects the operation of the exhaust valve and inputs the detected exhaust valve to the controller, and the controller opens and closes the exhaust control valve based on an exhaust valve operation signal from the exhaust valve gap sensor. It is comprised so that it may change.

  With this configuration, the opening timing (opening time) of the intake valve based on the intake valve actuation signal detected by the intake valve gap sensor, or the opening of the exhaust valve based on the exhaust valve actuation signal detected by the exhaust valve gap sensor. Since the opening / closing timing (opening time) of the exhaust control valve is changed based on the valve timing (valve opening time), the opening / closing of the exhaust control valve can be controlled by time control, and the timing based on the crank angle of the crank angle detector etc. Control is not required and control is simplified.

In this invention, the exhaust control valve is preferably configured in the following two forms.
(1) wherein the exhaust control valve, to configure the rotary valve for varying an exhaust passage area by rotating the valve shaft around.
With this configuration, since the exhaust control valve is a rotary valve, the structure is simple and the operating resistance is reduced.
(2) the exhaust control valve, to configure at position controllable poppet valve with opening and closing the exhaust passage by detaching the reciprocating driven by the valve seat.
If comprised in this way, since a poppet valve has high durability with respect to high temperature gas, if it uses for the exhaust control valve which opens and closes the exhaust gas passage for high temperature EGR, high durability will be acquired.

According to the present invention, when the exhaust valve is sub-lifted, the exhaust control valve is controlled to open and close based on the detected value of the engine operating condition. Therefore, the engine operation is related to the sub-lift when the sub-lift is set independently from the main lift of the exhaust valve. The exhaust control valve is controlled to open and close depending on conditions, and the internal EGR amount and the internal EGR timing can be freely controlled regardless of the overlap timing of the exhaust valve and the intake valve.
As a result, the internal EGR amount and the internal EGR timing can be freely controlled in combination with the sub-lift set to the exhaust valve and the opening / closing control of the exhaust control valve, thereby reducing NOx (nitrogen oxides) without degrading the engine performance. ) It can be accurately controlled to an appropriate value that can reduce the generation amount.

  Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this example are not intended to limit the scope of the present invention only to specific examples unless otherwise specified. Only.

FIG. 1 is an overall configuration diagram of an internal EGR system in a four-cycle diesel engine according to a first embodiment of the present invention. In the figure, 2 is a piston of an engine (diesel engine), 7 is a cylinder liner, 8 is a cylinder head, and 1 is a combustion chamber defined by the piston 2, cylinder liner 7 and cylinder head 8.
Reference numeral 5 denotes an intake port, 3 denotes an intake valve that opens and closes the intake port 5, 14 denotes an intake valve spring, 6 denotes an exhaust port, 4 denotes an exhaust valve that opens and closes the exhaust port 6, and 15 denotes an exhaust valve spring. 018 is an intake cam, 017 is a push rod, and 016 is a rocker arm. The intake cam 018 pushes up the push rod 017 and pushes down the intake valve 3 against the spring force of the intake valve spring 14 via the rocker arm 016. The intake valve 3 is opened.
Although not shown, the exhaust valve 4 is also provided with an exhaust cam, a push rod, and a rocker arm as in the case of the intake valve 3.
The above configuration is the same as that of a normal four-cycle diesel engine.

Reference numeral 20 denotes an exhaust control valve provided in the exhaust port 6, and in this embodiment, the exhaust control valve is supported by a support shaft 20a and is configured as a throttle valve (rotary valve) that can rotate about the axis of the support shaft 20a. Reference numeral 12 denotes an exhaust control valve drive motor for driving the intake control valve 20 via a link 13, and in this embodiment, a stepping motor is configured. Reference numeral 11 denotes a motor control device that controls the exhaust control valve drive motor 12.
21 is an engine speed detector for detecting the engine speed (engine speed), 22 is an engine load detector for detecting the engine load (engine load), and 23 is a crank angle detection for detecting the engine crank angle. , 24 is a cylinder discrimination signal transmitter for transmitting an ignition sequence signal of each cylinder (cylinder).
Reference numeral 10 denotes a controller, the detected value of the engine speed from the engine speed detector 21, the detected value of the engine load from the load detector 22, and the detected value of the crank angle from the crank angle detector 23. An ignition sequence signal for each cylinder is input from the discrimination signal transmitter 24, and calculation and control described later are performed based on these input signals, and the result is output to the motor control device 11.

FIG. 3 shows an exhaust control valve 20 configured as a poppet valve in the first embodiment.
Reference numeral 122 denotes a valve seat of the exhaust control valve 20 including the poppet valve. The position of the exhaust control valve 20 including the poppet valve is controlled by a lift controller 121 connected to the controller 10 for its lift H.
Thus, in this modified example, the exhaust control valve 20 is constituted by a poppet valve that is reciprocally driven to open and close the exhaust port 6 by being attached to and detached from the valve seat 122 and whose position can be controlled. 121 is configured to change the lift H of the exhaust control valve 20 according to a control signal from the controller 10.
If comprised in this way, since a poppet valve has high durability with respect to high temperature gas, if it uses for the exhaust control valve 20 which opens and closes the high temperature EGR exhaust port 6, high durability will be acquired.
Other configurations are the same as those of the embodiment of FIG. 1, and the same members are denoted by the same reference numerals.

  FIG. 4 is an opening / closing timing diagram of the exhaust valve and the intake valve in the first embodiment. In this embodiment, the lift of the exhaust valve 4 is moved to the exhaust cam (not shown) and the main lift L1 including the exhaust valve 4 fully opened and the sub-lift of the lift smaller than the start of the intake valve 3 and smaller than the main lift L1. L2 is formed. α1 is the start timing of the exhaust valve sublift L2, α2 is the end timing of the exhaust valve sublift L2, and αm is the maximum lift position of the exhaust valve sublift L2.

When the four-cycle diesel engine having the internal EGR system having such a configuration is operated, as shown in FIG. 4, when the exhaust valve 4 is opened by the sub-lift L2 during the opening period of the intake valve 4, as shown by the arrow in FIG. In addition, the exhaust gas in the exhaust port 6, that is, EGR gas flows into the combustion chamber 1, and internal EGR is performed.
The amount of EGR gas flowing into the combustion chamber 1 in this case, that is, the EGR amount, is determined by the opening degree or the opening period of the exhaust control valve 20 when the exhaust valve 4 is opened by the sub-lift L2.

FIG. 2 is an operation explanatory view of the first embodiment. In the figure, the arrow on the exhaust valve 4 side indicates the flow of exhaust gas (EGR gas), and the arrow on the intake valve 3 side indicates the flow of intake air.
In FIG. 2 (A), the exhaust valve 4 is opened with the sub-lift L2 and the exhaust control valve 20 has the maximum opening, and the internal EGR amount is maximum.
In FIG. 2 (C), the exhaust valve 4 is opened with the sub-lift L2, and the opening degree of the exhaust control valve 20 is minimized, so that the internal EGR amount is minimized.
In FIG. 2 (B), the exhaust valve 4 is opened at the sub-lift L2 and the exhaust control valve 20 is at an intermediate opening, and the internal EGR amount is an intermediate amount.
2, the same members as those in FIG. 1 are denoted by the same reference numerals.

Next, FIGS. 5 to 7 are control block diagrams of the exhaust control valve 20 in the first embodiment. FIG. 5 shows a case where the opening degree of the exhaust control valve is controlled, and FIG. When the period is controlled, FIG. 7 shows a case where the exhaust control valve and the valve opening phase of the exhaust valve are controlled.
5A, the detected value of the engine speed from the engine speed detector 21, the detected value of the engine load from the load detector 22, the detected value of the crank angle from the crank angle detector 23, The ignition sequence signal of each cylinder from the cylinder discrimination signal transmitter 24 is input to the exhaust control valve opening calculation unit 101 of the controller 10.

  An exhaust valve opening / closing timing setting unit 102 sets the opening / closing timing and lift of the exhaust valve 4 in combination with the main lift L1 and the sublift L2 of the exhaust valve 4 as shown in FIG. Reference numeral 103 denotes an exhaust control valve opening setting section. When the intake valve 3 is opened, the opening of the exhaust control valve 20 decreases as the engine speed or the engine load increases as shown in FIG. Is set to be fully closed (inclination angle θ = 90 °) when the engine is operated at a high rotational speed of a certain rotational speed N0 or higher, a constant load L0 or higher, or a high load operation.

The exhaust control valve opening calculation unit 101 calculates the opening of the exhaust control valve 20 corresponding to the detected value of the engine speed or the detected value of the engine load from the exhaust control valve opening setting unit 103, and The sub-lift L2 of the exhaust valve 4 set in the exhaust valve opening / closing timing setting unit 102 and the start timing α1 and end timing α2 of the sub-lift L2 are matched, and synchronized with the sub-lift L2 of the exhaust valve 4 by the detected value of the crank angle, Further, the operation signal of the exhaust control valve 20 for each cylinder according to the ignition order of each cylinder is output to the motor controller 11 using the ignition order signal of each cylinder.
In the motor control device 11, the exhaust control valve drive motor 12 of each cylinder is operated based on the operation signal of the exhaust control valve 20 for each cylinder, and the exhaust control valve 20 is opened and closed by the opening degree.
As a result, when the intake valve 3 is opened, the exhaust gas that flows into the combustion chamber 1 from the exhaust port 6 with the opening degree of the exhaust control valve 20 increased in the low rotation range or low load range when the exhaust valve 4 is in the sub-lift L 2. The internal EGR is increased by increasing the amount (EGR gas amount), the opening of the exhaust control valve 20 is decreased as the engine speed or engine load increases, and the EGR gas amount is decreased. When the engine that does not require EGR is operated at a high rotational speed or a high load operation at a constant rotational speed N0 or higher or a constant load L0 or higher, the intake control valve 20 can be fully closed to stop the internal EGR.

  Next, in the case of controlling the valve opening period of the exhaust control valve 20 as shown in FIG. 6A, the exhaust control valve opening period setting unit 105 has an intake air as shown in FIG. When the valve 3 is opened, the opening degree of the exhaust control valve 20 is kept constant, and the opening period of the exhaust control valve 20 becomes shorter as the engine speed or the engine load increases. The valve opening period is set to zero (0) during the sub-lift L2 at the time of high rotation or high load operation.

The exhaust control valve opening period calculation unit 104 calculates the valve opening period of the exhaust control valve 20 corresponding to the detected value of the engine speed or the detected value of the engine load from the valve opening period setting unit 105, and The sub-lift L2 of the exhaust valve 4 set in the exhaust valve opening / closing timing setting unit 102 and the start timing α1 and end timing α2 of the sub-lift L2 are matched, and synchronized with the sub-lift L2 of the exhaust valve 4 by the detected value of the crank angle, Further, the operation signal of the exhaust control valve 20 for each cylinder according to the ignition order of each cylinder is output to the motor controller 11 using the ignition order signal of each cylinder.
The subsequent control and operation are the same as in FIG.

  Next, when the opening phase of the exhaust control valve 20 and the sub-lift L2 of the exhaust valve 4 is controlled when the intake valve 3 is opened as shown in FIG. 7, the exhaust control valve / exhaust valve opening phase is controlled. As shown in FIG. 7B, the setting unit 107 has a constant opening degree of the exhaust control valve 20, and the opening period of the exhaust control valve 20 and the sub-lift of the exhaust valve 4 as the engine speed or engine load increases. The overlap period with the L2 period (α1 to α2 period in FIG. 4) becomes small, and when the rotation speed is higher than the constant rotational speed N0 or higher than the constant load L0, or the high load operation, the overlap period becomes zero (0), and the exhaust The control valve 20 is set to be substantially fully closed.

Then, the exhaust control valve / exhaust valve opening phase calculation unit 106 determines the exhaust control valve / exhaust valve opening phase corresponding to the detected value of the engine speed or the detected value of the engine load as the exhaust control valve / exhaust valve opened phase. Calculated from the valve phase setting unit 107, synchronized with the sub-lift L2 of the exhaust valve 3 by the detected value of the crank angle, and further, for each cylinder according to the firing order of each cylinder, using the firing order signal of each cylinder The operation signal of the exhaust control valve 20 is output to the motor control device 11.
The subsequent control and operation are the same as in FIG.

  Therefore, according to the first embodiment, the exhaust valve 3 is connected to the main lift L1 including the exhaust valve 3 fully opened, and the sub-lift L2 of the lift is delayed from the start of the intake valve 3 and smaller than the main lift L1. And the exhaust control valve 20 that opens and closes the exhaust port 6 to change the exhaust passage area is installed in the exhaust port 6. When the intake valve 3 is opened and the exhaust control valve 20 is opened during the sublift L2 of the exhaust valve 4, a part of the exhaust gas in the exhaust port 6 passes through the exhaust valve 4 in the sublift L2 state and enters the combustion chamber 1. Introduced and internal EGR done.

The opening degree or opening / closing timing of the exhaust control valve 20 or the valve opening phase between the exhaust control valve 20 opening period and the sub-lift L2 period of the exhaust valve 4 during the sub-lift L2 of the exhaust valve 4 is determined by the controller 10 according to engine rotation. Control is performed based on engine operating condition detection values such as number detection values and engine load detection values.
Accordingly, when the intake valve 3 is opened, the exhaust control valve 20 is opened to allow the combustion chamber 1 and the exhaust port 6 to communicate with each other under the control of the controller 10 from the start of the engine requiring internal EGR to the low load operation. The internal EGR can be stopped by closing the exhaust control valve 20 during the sub-lift L2 of the exhaust valve 4 when the engine does not require the internal EGR and the engine is in a high load operation.

Therefore, according to the first embodiment, the exhaust control valve 20 is controlled to open and close based on the engine operating condition detection values such as the engine speed detection value and the engine load detection value when the sub-lift L2 of the exhaust valve 4 is performed. The EGR from the exhaust passage is not uniquely determined by the overlap timing of the exhaust valve and the intake valve, but is related to the sublift L2 when the sublift L2 is set independently from the main lift L1 of the exhaust valve 4. The exhaust control valve 20 is controlled to open and close depending on the engine operating conditions, and the internal EGR amount and the internal EGR timing can be freely controlled regardless of the overlap timing of the exhaust valve 4 and the intake valve 3.
Thereby, the internal EGR amount and the timing of the internal EGR can be freely controlled by combining the sublift L2 set to the exhaust valve 4 and the opening / closing control of the exhaust control valve 20, thereby reducing NOx (without degrading the engine performance). Nitrogen oxide) can be accurately controlled to an appropriate value that can reduce the generation amount.

FIG. 8 is a diagram corresponding to FIG. 1 showing a second embodiment of the present invention, and FIG. 9 is a control block diagram of an exhaust control valve in the second embodiment.
In the second embodiment, time control based on the intake valve actuation signal from the intake valve gap sensor 30 is used instead of the timing control based on the crank angle of the crank angle detector 23 and the like in the first embodiment.
That is, in FIG. 8, reference numeral 30 denotes an intake valve gap sensor that detects a gap at the top of the intake valve 3, and an intake valve operation signal from the intake valve gap sensor 30 is input to the controller 10.

Next, in FIG. 9, the detected value of the engine speed from the engine speed detector 21, the detected value of the engine load from the load detector 22, and the detected value of the intake valve operation signal from the intake valve gap sensor 30. The ignition sequence signal of each cylinder from the cylinder discrimination signal transmitter 24 is input to the exhaust control valve opening / closing period calculation unit 104 of the controller 10.
The subsequent control and operation are the same as those in the block diagram shown in FIG.
Other configurations are the same as those of the first embodiment, and the same members or elements are denoted by the same reference numerals.

  Although not shown in the third embodiment of the present invention, the exhaust valve gap sensor 31 (see FIG. 9) is used instead of the timing control by the crank angle of the crank angle detector 23 and the like in the first embodiment. The time control based on the exhaust valve actuation signal from can also be used. The exhaust valve gap sensor 31 can be the same as the intake valve gap sensor 30, and the exhaust valve operation signal from the exhaust valve gap sensor 31 is input to the controller 10 as shown in FIG. 9.

Next, in FIG. 9, the detected value of the engine speed from the engine speed detector 21, the detected value of the engine load from the load detector 22, and the detected value of the exhaust valve operation signal from the exhaust valve gap sensor 31. The ignition sequence signal of each cylinder from the cylinder discrimination signal transmitter 24 is input to the exhaust control valve opening / closing period calculation unit 104 of the controller 10.
The subsequent control and operation are the same as those in the block diagram shown in FIG.

According to the second and third embodiments, the opening timing (opening time) of the intake valve 3 or the exhaust valve detected by the exhaust valve gap sensor 31 based on the intake valve actuation signal detected by the intake valve gap sensor 30. Since the opening / closing timing (opening time) of the exhaust control valve 20 is changed based on the opening timing (opening time) of the exhaust valve 4 by the operation signal, the opening / closing of the exhaust control valve 20 can be controlled by time control. The timing control by the crank angle of the angle detector 23 or the like is not required, and the control becomes simple.
Other configurations are the same as those of the first embodiment, and the same members or elements are denoted by the same reference numerals.

  According to the present invention, the amount of NOx (nitrogen oxide) generated can be reduced without degrading the engine performance by freely adapting the internal EGR amount and the internal EGR timing to the engine operating conditions and the exhaust valve open state. It is possible to provide a four-cycle engine having an internal EGR system that can be controlled to a proper value.

1 is an overall configuration diagram of an internal EGR system in a 4-cycle diesel engine according to a first embodiment of the present invention. (A), (B), (C) is operation explanatory drawing in the said 1st Example. FIG. 6 is a view corresponding to FIG. 1 showing a modification of the exhaust control valve in the first embodiment. It is an opening-and-closing timing diagram of an exhaust valve and an intake valve in the 1st example. It is a control block diagram (the 1) of the exhaust control valve in the said 1st Example. It is a control block diagram (the 2) of the exhaust control valve in the said 1st Example. It is a control block diagram (the 3) of the exhaust control valve in the said 1st Example. FIG. 3 is a view corresponding to FIG. 1 showing a second embodiment of the present invention. It is a control block diagram of the exhaust control valve in the second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Combustion chamber 2 Piston 3 Intake valve 4 Exhaust valve 5 Intake port 6 Exhaust port 7 Cylinder liner 8 Cylinder head 10 Controller 11 Motor control device 12 Exhaust control valve drive motor 018 Intake cam 20 Exhaust control valve 21 Rotation speed detector 22 Load detection 23 Crank angle detector 24 Phase discrimination signal transmitter 30 Intake valve gap sensor 31 Exhaust valve gap sensor

Claims (3)

In a four-cycle engine equipped with an internal EGR system (exhaust gas recirculation system) that lifts the exhaust valve when the intake valve is opened to recirculate a part of the exhaust gas in the exhaust passage into the combustion chamber and mix it with the intake air.
The exhaust valve, as well as configured to open in two lifts form the main lift and also delayed from the time the start of the opening of the intake valves and the smaller lift than the main lift Saburifuto including fully open exhaust valves An exhaust control valve that opens and closes the exhaust passage when the exhaust valve is sub-lifted to change the exhaust passage area, and opens and closes the exhaust control valve during the sub-lift to open the combustion chamber from within the exhaust passage. is configured to adjust the recirculation amount of exhaust gas (EGR amount) fed in,
Exhaust control valve drive device for driving the exhaust control valve, engine speed detector, engine load detector, engine speed detection value from the engine speed detector and engine load detection from the engine load detector A controller for controlling the operation of the exhaust control valve drive device based on the engine speed detection value and the engine load detection value of the engine load detection value.
The controller is configured to change the opening / closing timing of the exhaust control valve by making the opening degree of the exhaust control valve constant via the exhaust control valve drive device based on the detected value of the engine operating condition, The internal EGR is configured to change the opening / closing timing of the exhaust control valve based on an operation signal from an intake valve gap sensor that detects the operation of the exhaust valve or an exhaust valve gap sensor that detects the operation of the exhaust valve. 4-cycle engine with system. 2. A four-cycle engine equipped with an internal EGR system according to claim 1 , wherein the exhaust control valve is constituted by a rotary valve that rotates around a valve shaft to change an exhaust passage area . 4. The internal EGR system according to claim 1, wherein the exhaust control valve is constituted by a poppet valve that can be reciprocally driven to open and close the exhaust passage by being attached to and detached from a valve seat and position-controlled. Cycle engine.

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