JP2009103093A - Diesel engine control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diesel engine control device capable of exhibiting the exhaust purifying function of an exhaust post-treating device in an early stage by raising an exhaust gas temperature appropriately without ejecting a large quantity of black smoke when an engine is in a cold state. <P>SOLUTION: When the diesel engine is in a predetermined cold operating state, an ECU 48 controls a valve timing switching mechanism 56 so that a part of the open period of an exhaust valve overlaps with the open period of an intake valve of the same cylinder as the exhaust valve and that the exhaust valve is opened/closed at the first opening/closing timing at which the opening start timing of the exhaust valve is on the delay side rather than the bottom dead center of a piston in the expansion stroke of the cylinder. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control device for a diesel engine, and more particularly to control of a diesel engine provided with a valve timing switching mechanism capable of changing the opening / closing timing of an exhaust valve of the engine, and an exhaust aftertreatment means having a function of purifying exhaust exhausted from the engine. Relates to the device.

Conventionally, a NOx catalyst for purifying exhaust by reducing NOx (nitrogen oxides) contained in the exhaust of a diesel engine, a particulate filter for collecting particulates and purifying the exhaust, etc. are provided after exhaust. It is used as a processing device.
For example, in recent years, the use of an ammonia selective reduction type NOx catalyst (hereinafter referred to as SCR catalyst) has been promoted as a NOx catalyst. In the exhaust aftertreatment device using the SCR catalyst, urea water is supplied to the upstream side of the SCR catalyst, and ammonia generated by hydrolysis of the urea water by heat of the exhaust is supplied to the SCR catalyst. The ammonia supplied to the SCR catalyst is once adsorbed by the SCR catalyst, and NOx reduction is performed by promoting the denitration reaction between this ammonia and NOx in the exhaust gas by the SCR catalyst.

  In order for the SCR catalyst to exhibit such an exhaust purification function satisfactorily, the temperature of the exhaust gas flowing into the SCR catalyst needs to rise to a temperature at which the SCR catalyst is activated. However, when the engine is cold, the temperature of the exhaust exhausted from the engine is low, and the exhaust pipe upstream of the SCR catalyst, the pre-stage oxidation catalyst, and the particulate filter are not sufficiently warmed. Therefore, the temperature of the exhaust gas flowing into the SCR catalyst is remarkably lowered. Due to such a decrease in the exhaust temperature, the SCR catalyst cannot perform the exhaust purification function as described above well.

  Further, such a problem due to a decrease in the exhaust temperature is not limited to the SCR catalyst, and similarly occurs in various catalysts and particulate filters used as an exhaust aftertreatment device. In other words, the catalyst used in the exhaust aftertreatment device does not activate the catalyst due to a decrease in the exhaust temperature, making it impossible to perform the catalyst function well, and the particulate filter is difficult to continuously regenerate. Curate accumulates on the particulate filter, and the particulate capturing function is reduced.

In order to solve such a problem when the exhaust temperature is lowered, Patent Document 1 proposes a valve timing control device that raises the exhaust temperature by changing the opening / closing timing of the exhaust valve of the engine when the engine is cold. ing.
In the control device of Patent Document 1, a mechanism is used in which the opening / closing timing of the exhaust valve is made variable by changing the phase between the crankshaft and the exhaust camshaft. When the engine temperature is low, the opening / closing timing of the exhaust valve is advanced by a predetermined crank angle. In this way, the combustion heat in the cylinder is positively discharged to the exhaust side, and the catalyst and the like are activated early by this combustion heat.
Japanese Patent Laid-Open No. 10-68332

  However, the control device disclosed in Patent Document 1 changes the phase between the crankshaft and the exhaust camshaft, thereby changing the opening / closing timing of the exhaust valve while keeping the valve opening period constant. By advancing the start timing, the exhaust valve closing completion timing is advanced from the exhaust top dead center, and the exhaust valve is closed before the intake valve is opened. Therefore, the residual gas in the cylinder is compressed again as the exhaust valve is closed, and the compressed residual gas is discharged from the intake port when the intake valve is subsequently opened. As a result, the intake of fresh air from the intake port into the cylinder is hindered, and the excess air ratio decreases, resulting in a problem that a large amount of black smoke is generated or HC (hydrocarbon) is discharged.

  In addition, the control device disclosed in Patent Document 1 changes the phase between the crankshaft and the exhaust camshaft by supplying hydraulic pressure. However, when the engine is cold, the operating oil to be supplied has a low temperature and thus has a low viscosity. The phase change mechanism cannot be stably controlled unless the temperature of the hydraulic oil rises to some extent and the viscosity of the hydraulic oil decreases. Therefore, it is conceivable that the control device of Patent Document 1 is configured such that the opening / closing period of the exhaust valve is most advanced when the temperature of the hydraulic oil is low. However, when the engine is in a high-load operation state when the temperature of the hydraulic oil has not risen sufficiently, control is performed to smoothly discharge the hydraulic oil and advance the opening / closing timing of such an exhaust valve most. Therefore, since the opening / closing timing of the exhaust valve is maintained at the most advanced state for a while, the amount of fresh air sucked into the cylinder remains reduced as described above. The temperature of the exhaust increases as the amount of fresh air to which the heat of combustion is transmitted decreases, but the amount of fresh air decreases significantly, resulting in a large amount of graphite due to incomplete combustion and an excessive increase in the exhaust temperature. May occur.

  The present invention has been made in view of the problems as described above, and an object of the present invention is to appropriately increase the exhaust temperature without discharging a large amount of black smoke when the engine is cold, and to perform an exhaust aftertreatment device. It is an object to provide a control device for a diesel engine that can exhibit its exhaust purification function at an early stage.

  In order to achieve the above object, a control device for a diesel engine according to the present invention includes a part of a valve opening period of an exhaust valve of a diesel engine that overlaps with a valve opening period of an intake valve of the same cylinder as the exhaust valve. A first opening / closing timing at which the opening timing of the exhaust valve is retarded from the bottom dead center of the piston in the expansion stroke of the cylinder, and a portion of the opening period of the exhaust valve is the opening period of the intake valve of the cylinder Valve timing switching that can be selectively switched to any one of a second opening / closing timing at which the opening timing of the exhaust valve is advanced from the opening timing of the first opening / closing timing. A mechanism, an exhaust aftertreatment device for purifying exhaust gas discharged from the diesel engine, and a predetermined cooling operation of the diesel engine at the first opening / closing timing. Serial exhaust valve and a controlling means for controlling the valve timing switching mechanism to open and close (Claim 1).

  According to the control apparatus for a diesel engine configured as described above, during a predetermined cold operation of the diesel engine, a part of the valve opening period of the exhaust valve is the opening period of the intake valve of the same cylinder as the exhaust valve. While overlapping, the valve timing switching mechanism is controlled so that the exhaust valve opens and closes at the first opening / closing timing at which the opening timing of the exhaust valve is retarded from the piston bottom dead center in the expansion stroke of the cylinder.

In the control device for the diesel engine, the opening timing of the exhaust valve at the first opening / closing timing is preferably set to 40 to 70 ° as a crank angle after the bottom dead center of the piston. .
According to the diesel engine control apparatus configured as described above, the exhaust valve is opened at a timing of 40 to 70 ° in the crank angle after the bottom dead center of the piston during the cold operation of the diesel engine.

Further, in the control apparatus for the diesel engine, the valve timing switching mechanism sets the opening / closing timing of the exhaust valve to the second opening / closing timing when hydraulic oil is supplied, while the exhaust timing when the hydraulic oil is not supplied. The valve opening / closing timing is defined as the first opening / closing timing (Claim 3).
According to the control apparatus for a diesel engine configured as described above, when the diesel engine is in a cold operation, the exhaust valve is opened / closed at the first opening / closing timing because hydraulic oil is not supplied to the valve timing switching mechanism.

  Further, in such a diesel engine control device, the control means controls the valve timing switching mechanism so that the opening / closing timing of the exhaust valve is set to the first opening / closing timing. Until it is determined that the temperature has risen above a predetermined temperature, switching of the opening / closing timing of the exhaust valve from the first opening / closing timing to the second opening / closing timing by the valve timing switching mechanism may be prohibited ( Claim 4).

According to the control apparatus for a diesel engine configured as described above, when the control unit controls the valve timing switching mechanism so that the exhaust valve opens and closes at the first opening / closing timing, the temperature of the hydraulic oil is equal to or higher than a predetermined temperature. The exhaust valve is opened / closed at the first opening / closing timing until it is determined that the valve has risen.
Further, in the control device for the diesel engine, when the control means determines that the diesel engine is in an operation state set in advance as an operation state in which the temperature of the exhaust gas decreases, the opening / closing timing of the exhaust valve is set to the first time. The valve timing switching mechanism may be controlled so as to be one opening / closing timing.

  According to the control apparatus for a diesel engine configured as described above, when the diesel engine is in an operation state set in advance as an operation state in which the exhaust gas temperature decreases, the exhaust valve opens and closes at the first opening / closing timing.

  According to the control apparatus for a diesel engine of the present invention, during the cold operation of the diesel engine, the first opening / closing timing at which the opening timing of the exhaust valve is retarded from the piston bottom dead center in the expansion stroke of the cylinder. Since the valve timing switching mechanism is controlled so that the exhaust valve opens and closes at the same time, the piston compresses the gas in the cylinder during the exhaust stroke, so that the pumping loss increases compared to when the exhaust valve opens and closes at the second opening and closing timing. To do. In order to compensate for the increased pumping loss, the amount of fuel supplied to each cylinder is increased. As a result, the temperature of the exhaust discharged from the diesel engine rises.

Further, the delay in the opening timing of the exhaust valve causes the amount of residual gas in the cylinder to increase compared to when the exhaust valve opens and closes at the second opening / closing timing, and the amount of fresh air sucked into the cylinder correspondingly increases. Decrease. Accordingly, the amount of fresh air to which heat generated by the combustion of fuel is transmitted is reduced, and as a result, the temperature of the exhaust gas rises.
Therefore, even during the cold operation, the exhaust gas temperature can be quickly raised and the exhaust gas aftertreatment device can exhibit the exhaust gas purification function.

  Further, even when the exhaust valve is opened and closed at the first opening / closing timing, the exhaust valve continues to be opened until a part of the valve opening period overlaps with the valve opening period of the intake valve. Thus, a significant increase in the amount of residual gas in the cylinder can be prevented. Accordingly, the supply of fresh air into the cylinder is not greatly hindered by the residual gas, and the amount of fresh air sucked into the cylinder is not significantly reduced. As a result, the exhaust temperature can be quickly raised while preventing discharge of black smoke or the like into the atmosphere.

Further, according to the control device for the diesel engine of the second aspect, during the cold operation, the exhaust valve starts to be opened at a crank angle of 40 to 70 ° after the bottom dead center of the piston. It is possible to quickly raise the exhaust temperature while preventing smoke and the like from being discharged into the atmosphere.
Since the viscosity of the hydraulic oil is high during the cold operation, it is difficult to perform the stable control by properly supplying the hydraulic oil to the valve timing switching mechanism. For example, during the cold operation, the exhaust valve is opened and closed at the first opening / closing timing without supplying hydraulic oil to the valve timing switching mechanism, so that the exhaust valve can be opened and closed stably and reliably at the first opening / closing timing. Further, when the diesel engine enters a high load operation state while the temperature of the hydraulic oil is not sufficiently increased during the cold operation, the exhaust valve is continuously opened and closed at the first opening / closing timing. However, as described above, since the opening of the exhaust valve is continued until a part of the opening / closing timing of the exhaust valve overlaps with the opening / closing timing of the intake valve, the residual gas in the cylinder can be reduced. As a result, since the amount of fresh air sucked into the cylinder is not significantly reduced, it is possible to prevent a large amount of graphite from being generated and an excessive increase in the exhaust gas temperature even in a high load operation state.

  According to the control device for a diesel engine of claim 4, when the control means controls the valve timing switching mechanism so that the exhaust valve opens and closes at the first opening / closing timing, the temperature of the hydraulic oil is equal to or higher than a predetermined temperature. The exhaust valve is opened / closed at the first opening / closing timing until it is determined that the temperature has risen, so that the temperature does not rise sufficiently and hydraulic fluid that remains high in viscosity is not supplied to the valve timing switching mechanism. As a result, the unstable operation of the valve timing switching mechanism due to the high-viscosity hydraulic oil can be prevented.

  According to the diesel engine control apparatus of the fifth aspect, the exhaust valve opens and closes at the first opening / closing timing when the diesel engine is in an operation state set in advance as an operation state in which the exhaust gas temperature decreases. The amount of exhaust gas supplied to the exhaust aftertreatment device is reduced, and it is possible to suppress the temperature drop of the exhaust aftertreatment device. As a result, it is possible to maintain the exhaust purification function of the exhaust aftertreatment device.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
A control device for a diesel engine according to an embodiment of the present invention is mounted on a vehicle. FIG. 1 is an overall configuration diagram of this diesel engine control device, and the configuration of the diesel engine control device according to the present invention will be described based on FIG.
A diesel engine (hereinafter referred to as an engine) 1 has a high-pressure accumulator chamber (hereinafter referred to as a common rail) 2 common to each cylinder, and high-pressure fuel supplied from a fuel injection pump (not shown) and stored in the common rail 2 is supplied to each cylinder. The fuel is supplied to the injectors 4 provided, and fuel is injected from the injectors 4 into the respective cylinders.

  The intake passage 6 is equipped with a turbocharger 8. The intake air drawn from an air cleaner (not shown) flows into the compressor 8a of the turbocharger 8 from the intake passage 6, and the intake air supercharged by the compressor 8a is intercooler. 10 to the intake manifold 12. The air introduced into the intake manifold 12 is drawn into each cylinder of the engine 1 via an intake port (not shown) by opening an intake valve (not shown) provided in each cylinder. An intake air amount sensor 14 for detecting an intake air flow rate to the engine 1 is provided upstream of the compressor 8a in the intake passage 6.

  On the other hand, an exhaust port (not shown) through which exhaust gas is discharged from each cylinder of the engine 1 by opening an exhaust valve (not shown in FIG. 1) is connected to an exhaust pipe 18 via an exhaust manifold 16. Has been. An EGR passage 22 is provided between the exhaust manifold 16 and the intake manifold 12 to communicate the exhaust manifold 16 and the intake manifold 12 via the EGR valve 20.

The exhaust pipe 18 is connected to the exhaust aftertreatment device 24 after passing through the turbine 8 b of the turbocharger 8. The rotating shaft of the turbine 8b is connected to the rotating shaft of the compressor 8a, and the turbine 8b receives the exhaust flowing in the exhaust pipe 18 to drive the compressor 8a.
The exhaust aftertreatment device 24 includes an upstream casing 26 and a downstream casing 30 that is communicated with the downstream side of the upstream casing 26 through a communication passage 28. A upstream oxidation catalyst 32 is accommodated in the upstream casing 26, and a particulate filter (hereinafter referred to as a filter) 34 is accommodated downstream of the upstream oxidation catalyst 32. The filter 34 is provided to purify the exhaust of the engine 1 by collecting particulates in the exhaust.

Since the front-stage oxidation catalyst 32 oxidizes NO in the exhaust gas to generate NO ₂ , by arranging the front-stage oxidation catalyst 32 and the filter 34 in this way, the particulates collected and deposited in the filter 34 are It reacts with NO ₂ supplied from the pre-stage oxidation catalyst 32 to oxidize, and the filter 34 is continuously regenerated.
On the other hand, an ammonia selective reduction type NOx catalyst (hereinafter referred to as an SCR catalyst) that adsorbs ammonia in the exhaust gas in the downstream casing 30 and selectively reduces NOx in the exhaust gas by using the adsorbed ammonia as a reducing agent to purify the exhaust gas. 36 is accommodated, and a downstream oxidation catalyst 38 for oxidizing ammonia flowing out of the SCR catalyst 36 into N ₂ is accommodated on the downstream side of the SCR catalyst 36.

The post-stage oxidation catalyst 38 also has a function of oxidizing CO (carbon monoxide) generated when the particulates are incinerated by forced regeneration of the filter 34, which will be described later, and discharging it to the atmosphere as CO ₂ (carbon dioxide). is doing.
The communication passage 28 is provided with a urea water injector 40 for injecting urea water into the exhaust gas in the communication passage 28. The urea water is supplied from a urea water tank 42 in which urea water is stored by a supply pump (not shown). As a result, urea water is injected from the urea water injector 40 into the exhaust gas in the communication passage 28.

The urea water injected from the urea water injector 40 is hydrolyzed by the heat of the exhaust to become ammonia, and is supplied to the SCR catalyst 36 together with the exhaust. The SCR catalyst 36 adsorbs the supplied ammonia and promotes a denitration reaction between the adsorbed ammonia and NOx in the exhaust gas, thereby purifying the exhaust gas with NOx being harmless N ₂ .
At this time, when ammonia flows out of the SCR catalyst 36 without reacting with NOx, the ammonia is oxidized by the post-stage oxidation catalyst 38 and is released into the atmosphere as harmless N ₂ . .

An inlet side temperature sensor 44 that detects the exhaust temperature on the inlet side of the SCR catalyst 36 is provided on the upstream side of the SCR catalyst 36 in the downstream casing 30.
Further, the engine 1 is provided with a valve timing switching mechanism (not shown in FIG. 1) for switching the opening / closing timing of the exhaust valve provided in each cylinder. As will be described later, the opening / closing timing of the exhaust valve can be switched by controlling the supply of hydraulic oil to the valve timing mechanism. The hydraulic oil control valve 46 shown in FIG. 1 is for controlling the supply of hydraulic oil to the valve timing switching mechanism.

An ECU (control means) 48 is provided to perform comprehensive control including operation control of the engine 1 configured as described above. The ECU 48 includes a CPU, a memory, a timer counter, and the like. The ECU 48 calculates various control amounts and controls various devices connected to the ECU 48 based on the control amounts.
On the input side of the ECU 48, in addition to the intake flow rate sensor 14 and the inlet side temperature sensor 44 described above, in order to collect information necessary for various controls, a water temperature sensor 50 that detects the temperature of the cooling water of the engine 1 and the engine 1 Various sensors such as a rotation speed sensor 52 for detecting the number of rotations and an accelerator opening degree sensor 54 for detecting a depression amount of an accelerator pedal (not shown) are connected. In addition, various devices such as the injector 4, the EGR valve 20, the urea water injector 40, and the hydraulic oil control valve 46 of each cylinder that are controlled based on the calculated control amount are connected to the output side of the ECU 48. .

  The ECU 48 also performs calculation of the fuel supply amount to each cylinder of the engine 1 and control of fuel supply from the injector 4 based on the calculated fuel supply amount. The fuel supply amount (main injection amount) necessary for the operation of the engine 1 is stored in advance based on the rotational speed of the engine 1 detected by the rotational speed sensor 52 and the accelerator opening detected by the accelerator opening sensor 54. It is determined by reading from the map. The amount of fuel supplied to each cylinder is adjusted by the valve opening time of the injector 4, and each injector 4 is driven to open in a driving time corresponding to the determined fuel amount, and main injection is performed in each cylinder. As a result, an amount of fuel necessary for the operation of the engine 1 is supplied.

In addition to such fuel supply control to each cylinder, the ECU 48 also performs control for forcibly regenerating the filter 34 to restore its function.
The particulates deposited on the filter 34 are oxidized and removed by continuous regeneration using the pre-stage oxidation catalyst 32 as described above. However, such continuous regeneration alone may not sufficiently remove particulates accumulated on the filter 34. If such a state continues, particulates may be excessively accumulated in the filter 34 and the filter 34 may be clogged. Therefore, the temperature of the filter 34 is appropriately increased according to the particulate accumulation state in the filter 34. By performing forced regeneration, the exhaust gas purification function of the filter 34 is maintained.

The particulate accumulation state is estimated based on the differential pressure upstream and downstream of the filter 34, the detection value of the intake air amount sensor 14, and the like, and when it is determined that the particulate accumulation amount on the filter 34 has reached a predetermined amount. The forced regeneration control is started.
In forced regeneration of the filter 34, HC (hydrocarbon) is supplied into the exhaust gas by performing post injection from the injector 4. Then, the temperature of the exhaust gas flowing into the filter 34 is raised by the HC oxidation reaction in the pre-stage oxidation catalyst 32, and the particulates deposited on the filter 34 are incinerated.

Further, the ECU 48 obtains a target supply amount of urea water necessary for selectively reducing NOx in the exhaust gas by the SCR catalyst 36, and controls the urea water injector 40 based on the target supply amount, whereby the urea water injector 40 is controlled. Is supplied to the exhaust gas upstream of the SCR catalyst 36.
As described above, the urea water injected from the urea water injector 40 is hydrolyzed by the heat of the exhaust gas to become ammonia, and is supplied to the SCR catalyst 36. The SCR catalyst 36 adsorbs the supplied ammonia and promotes a denitration reaction between the adsorbed ammonia and NOx in the exhaust, thereby reducing NOx to harmless N ₂ and purifying the exhaust.

  In order for such forced regeneration of the filter 34 and selective reduction of NOx by the SCR catalyst 36 to be performed satisfactorily, the pre-stage oxidation catalyst 32 and the SCR catalyst 36 must be activated. Furthermore, in the selective reduction of NOx by the SCR catalyst 36, in order to supply an appropriate amount of ammonia to the SCR catalyst 36, the urea water supplied into the exhaust gas from the urea water injector 40 must be hydrolyzed well by the heat of the exhaust gas. I must. For this reason, the exhaust temperature of the engine 1 must reach a temperature at which the pre-stage oxidation catalyst 32 and the SCR catalyst 36 can be activated.

Therefore, in the control device of the present embodiment, the exhaust temperature is raised by changing the opening / closing timing of the exhaust valve in the operating state of the engine 1 in which the exhaust temperature does not reach such a temperature. Yes.
Hereinafter, the configuration of the valve timing switching mechanism provided in each cylinder in order to change the opening / closing timing of the exhaust valve will be described with reference to FIGS.

2 is a view showing the assembly of the first rocker arm 58 and the second rocker arm 60 constituting the valve timing switching mechanism 56, FIG. 3 is a top view of the valve timing switching mechanism 56, and FIG. 4 shows the assembled state of the second rocker arm 60. FIG.
Each cylinder of the engine 1 is provided with a first rocker arm 58 and a second rocker arm 60 adjacent to each other so as to be swingably supported by the rocker shaft 62. The first rocker arm 58 is provided with a boss portion 64 through which the rocker shaft 62 is inserted, and the first rocker arm 58 is pivotally supported by the rocker shaft 62 via the boss portion 64. A shaft portion 66 that protrudes from the boss portion 64 of the first rocker arm 58 in the axial direction of the rocker shaft 62 and passes through the rocker shaft 62 is fitted into the boss portion 68 of the second rocker arm 60, so that the second rocker arm 60 is inserted. Is pivotally supported by the shaft portion 66 of the first rocker arm 58, so that the second rocker arm 60 can swing with respect to the rocker shaft 62.

  A roller 74 abutting on the first cam 72 is rotatably mounted on the end of the arm 70 extending to one side of the first rocker arm 58, and the valve shaft of the exhaust valve 78 is mounted on the end of the arm 76 extending to the other side. It is connected. The roller 74 of the first rocker arm 58 is pressed against the first cam 72 by receiving the urging force of a valve spring (not shown) provided in the exhaust valve 78 connected to the arm 76 of the first rocker arm 58. Has been.

  Further, the end of the arm 80 extending in the same direction as the arm 70 of the first rocker arm 58 from the boss portion 68 of the second rocker arm 60 contacts the second cam 82 having a cam profile different from that of the first cam 72. A contact roller 84 is rotatably mounted. The second rocker arm 60 is urged in a direction in which the roller 84 is pressed against the second cam 82 by a return spring 88 that engages with an end of a thick portion 86 formed on the upper portion of the boss portion 68.

  The boss portion 64 of the first rocker arm 58 is formed with a cylinder portion 90 having an axis in a direction substantially perpendicular to the axis of the rocker shaft 62, and the operating piston 92 slides on the cylinder portion 90. Installed as possible. The working piston 92 is driven by receiving the hydraulic pressure of the working oil supplied to the oil chamber 96 formed below the working piston 92 via an oil passage 94 formed inside the rocker shaft 62 as will be described later. When the hydraulic oil is not supplied to the oil chamber 96 and is not driven, it is pressed by the return spring 98 and located at the lower part of the cylinder portion 90 as shown in FIG. The operating piston 92 resists the return spring 98 by the hydraulic pressure of the operating oil and moves to the upper part of the cylinder portion 90 as shown in FIG.

As shown in FIGS. 5 and 6, the operating piston 92 is formed with an engaging groove 104 including a deep groove portion 100 and a shallow groove portion 102. Corresponding to the engagement groove 104, an engagement protrusion 106 projects from the second rocker arm 60 toward the first rocker arm 58 side and extends toward the working piston 92 above the arm 70 of the first rocker arm 58. It is installed.
As shown in FIG. 6, the engagement protrusion 106 is provided with the second rocker arm 60 driven by the second cam 82 when the hydraulic oil is supplied to the oil chamber 96 and the operating piston 92 is positioned at the upper part of the cylinder portion 90. As the swaying motion proceeds, it moves into the shallow groove portion 102 of the working piston 92 and comes into contact with the working piston 92 in the swaying direction, thereby transmitting the swaying motion of the second rocker arm 60 to the first rocker arm 58.

  On the other hand, as shown in FIG. 5, when the operating piston 92 is positioned below the cylinder portion 90 without supplying hydraulic oil to the oil chamber 96, the second rocker arm 60 driven by the second cam 82 is swung. Accordingly, the engaging protrusion 106 enters the deep groove portion 100 of the operating piston 92. At this time, the engaging protrusion 106 does not contact the operating piston 92 in the swing direction, and the swing of the second rocker arm 60 is the first. Transmission to the rocker arm 58 is prevented.

The supply of the hydraulic oil to the oil chamber 96 and the discharge of the hydraulic oil from the oil chamber 96 are performed by the ECU 48 controlling the hydraulic oil control valve 46 as described above.
The cam profiles of the first cam 72 and the second cam 82 are set so that the lift amount of the exhaust valve 78 by the first cam 72 is always equal to or less than the lift amount of the exhaust valve 78 by the second cam 82. Accordingly, the hydraulic oil is supplied to the oil chamber 96 as described above, and the engagement protrusion 106 comes into contact with the operation piston 92 located at the upper part of the cylinder portion 90, thereby causing the second rocker arm 60 to swing. When transmitting to 58, the first rocker arm 58 swings according to the cam profile of the second cam 82, whereby the exhaust valve 78 is opened and closed.

On the other hand, when hydraulic oil is not supplied to the oil chamber 96 and the operating piston 92 is positioned below the cylinder portion 90, the swing of the second rocker arm 60 is not transmitted to the first rocker arm 58 as described above. 78 is opened and closed by a first rocker arm 58 that swings according to the cam profile of the first cam 72.
In this embodiment, the cam profiles of the first cam 72 and the second cam 82 are such that the opening / closing timing based on the lift amount and the crank angle when the exhaust valve 78 is driven by the respective cams has the characteristics shown in FIG. Is set to

  That is, in FIG. 7, the lift amount and opening / closing timing (first opening / closing timing) of the exhaust valve 78 due to the cam profile of the first cam 72 are indicated by the curve EX1, and the lift amount of the exhaust valve 78 due to the cam profile of the second cam 82 The opening / closing timing (second opening / closing timing) is indicated by a curve EX2. A curve IN in FIG. 7 shows the lift amount and opening / closing timing of the intake valve used in combination with the exhaust valve 78.

  As shown by the curve EX2 in FIG. 7, when the exhaust valve 78 is opened and closed by the second cam 82, the opening timing of the exhaust valve 78 is earlier than the bottom dead center (BDC) of the expansion stroke, and the valve closing is completed. The timing is later than the opening start timing of the intake valve, and a part of the opening period of the exhaust valve 78 overlaps with the opening period of the intake valve. Such characteristics of the second cam 82 are equivalent to those of a cam for driving an exhaust valve used in a general diesel engine not provided with a valve timing switching mechanism.

  On the other hand, when the exhaust valve 78 is opened and closed by the first cam 72, the opening start timing of the exhaust valve 78 is cranked from the bottom dead center (BDC) in the expansion stroke, as shown by the curve EX1 in FIG. The angle is on the retarded side by A (°). The retardation amount A from the BDC is set to 40 to 70 ° for the reason described later. Further, a part of the opening period of the exhaust valve 78 overlaps with the opening period of the intake valve, and the closing timing of the exhaust valve 78 is the closing timing of the exhaust valve 78 in the case of the second cam 82. Is almost the same.

  As described above, the valve opening start timing of the exhaust valve 78 is greatly retarded from the valve opening start timing when the exhaust valve 78 is opened and closed by the second cam 82, but the exhaust valve 78 is opened and closed by the first cam 72. In this case, by setting the lift amount L1 of the exhaust valve 78 to 1/5 to 1/3 of the lift amount L2 of the exhaust valve 78 in the case of the second cam 82, the exhaust valve 78 is opened and closed by the first cam 72. Even in this case, the change rate of the lift amount of the exhaust valve 78 is set to an appropriate range so that the exhaust valve 78 can be opened and closed without any trouble.

  That is, when the exhaust valve 78 is opened and closed by the second cam 82, the exhaust valve 78 closing timing is substantially coincided and only the valve opening start timing is retarded by 40 to 70 ° from the BDC. If the lift amount remains at L2, the marginal load of the valve spring of the exhaust valve 78 is remarkably reduced, causing problems in the dynamic characteristics of the exhaust valve 78 such as jumping of the exhaust valve 78. Therefore, in order to prevent such a problem, it is necessary to set the lift amount L1 of the exhaust valve 78 to 1/5 to 1/3 of the lift amount L2 of the exhaust valve 78 in the case of the second cam 82. .

Next, the temperature rise of the exhaust using the valve timing switching mechanism 56 configured as described above will be described.
FIG. 8 shows that the engine 1 is operated in a constant operation state with medium and medium loads, and when the exhaust valve 78 is opened and closed by the first cam 72 in the control device of this embodiment, the exhaust valve 78 is opened by the second cam 82. The opening timing of the exhaust valve 78, the excess air ratio λ, and the exhaust temperature Tti when only the opening timing is gradually delayed from the opening / closing timing of the general exhaust valve 78 that opens and closes. The excess air ratio λ is indicated by a solid line, and the exhaust temperature Tti is indicated by a one-dot chain line. The valve opening start timing of the exhaust valve 78 is represented by a crank angle, where BDC is 0 ° and the advance side of BDC is represented by a positive value and the retard side is represented by a negative value. The exhaust temperature Tti is the inlet side temperature of the turbine 8b of the turbocharger 8.

  As shown in FIG. 8, it can be seen that the exhaust gas temperature Tti increases as the opening start timing of the exhaust valve 78 is retarded, but the valve opening start timing is changed to a crank angle of 40 ° (−40 ° BBDC) after BDC. By setting the angle, the exhaust temperature rises to 400 ° C. or more, while the excess air ratio λ is about 2.3, and a value of 1.5 or more is secured. Thus, the reason why the exhaust gas temperature rises by delaying the valve opening start timing of the exhaust valve 78 is as follows.

  That is, since the opening start timing of the exhaust valve 78 is delayed, the pumping loss of each cylinder increases as the piston compresses the gas in the cylinder, but the ECU 48 has the accelerator opening detected by the accelerator opening sensor 54. In order to obtain the corresponding engine output, the amount of fuel supplied from the injector 4 to each cylinder is increased so as to compensate for the increased pumping loss in this way, and as a result, the temperature of the exhaust discharged from the engine 1 rises. is there.

Further, since the opening start timing of the exhaust valve 78 is delayed, the amount of residual gas in the cylinder increases compared to when the exhaust valve 78 is opened and closed by the second cam 82, and the new air drawn into the cylinder by that amount. The amount of decreases. Accordingly, the amount of fresh air to which heat generated by fuel combustion is transmitted is small, and the temperature of the exhaust gas rises.
Further, when the opening timing of the exhaust valve 78 is retarded, the excess air ratio λ decreases with the delay of the opening timing of the exhaust valve 78, but the opening timing is 70 after BDC. Even in the case of a crank angle of ° (−70 ° BBDC), the excess air ratio λ is about 2.0, and a value of 1.5 or more is secured. As described above, the reason why the excess air ratio λ does not decrease greatly even when the opening timing of the exhaust valve 78 is delayed is as follows.

  That is, even when the opening timing of the exhaust valve 78 is delayed, as described above, the exhaust valve 78 is opened until a part of the valve opening period of the exhaust valve 78 overlaps with the valve opening period of the intake valve. The valve continues. For this reason, although the residual gas in the cylinder increases due to the retarded opening timing of the exhaust valve 78, it does not increase significantly. Therefore, the supply of fresh air into the cylinder is not greatly hindered by the residual gas, and a sufficient excess air ratio can be ensured without greatly reducing the amount of fresh air supplied.

  When the excess air ratio λ decreases, it is known that black smoke is likely to be generated when the value falls below 1.5, but when the valve opening start timing is a crank angle of 70 ° after BDC, As described above, the excess air ratio λ is about 2.0, and a value of 1.5 or more can be secured. Therefore, black smoke is not generated due to a decrease in the excess air ratio λ. At this time, the exhaust temperature further rises to 500 ° C. or higher. Therefore, by setting the opening timing of the exhaust valve 78 to a crank angle of 40 to 70 ° after the BDC, a satisfactory temperature rise of the exhaust gas is realized while maintaining the excess air ratio λ at a value that does not generate black smoke. It becomes possible.

Note that when the opening start timing of the exhaust valve 78 is retarded, the exhaust temperature rises compared to when it is not retarded. Therefore, in consideration of the reliability of the engine 1, the exhaust temperature is preset in this embodiment. The ECU 48 is provided with a function of interrupting fuel injection from the injector 4 when the maximum exhaust temperature is exceeded.
For comparison with FIG. 9, FIG. 9 is similar to the device disclosed in Patent Document 1 described above. By changing the phases of the crankshaft and the exhaust camshaft, the exhaust valve can be opened and closed while the valve opening period remains constant. The relationship between the exhaust valve opening start timing, the excess air ratio λ, and the exhaust temperature Tti when the timing is variable and the exhaust valve opening start timing is advanced is the same as in FIG. It is a graph to show.

  As shown in FIG. 9, even when both the valve opening start timing and the valve closing completion timing are advanced, the exhaust temperature Tti increases with the advance of the valve opening start timing. It can be seen that the excess air ratio λ significantly decreases in response to. In this way, the excess air ratio λ decreases because the exhaust valve opening start timing advances and the valve closing completion timing also advances, so the exhaust valve closes before the intake valve opens, This is because a large amount of gas remains in the cylinder, which greatly inhibits the intake of fresh air into the cylinder.

Since the excess air ratio λ is thus greatly reduced, for example, when the exhaust temperature is raised to 600 ° C., the excess air ratio λ decreases to about 1.3 to 1.4, and a large amount of black Smoke will be generated.
On the other hand, in the present embodiment, as described above, the temperature of the exhaust gas can be raised satisfactorily without generating black smoke due to the decrease in the excess air ratio λ, so the comparative example as shown in FIG. It can be seen that it is greatly superior to.

Using the valve timing switching mechanism 56 as described above, the ECU 48 performs exhaust gas temperature raising control according to the operating state of the engine 1. This exhaust temperature raising control is repeatedly executed during the operation of the engine 1 at a predetermined control cycle based on the flowchart of FIG.
When the exhaust gas temperature raising control is started, first, in step S1, the ECU 48 determines whether or not the engine 1 is in a cold operation state based on the detection value of the water temperature sensor 50. That is, the ECU 48 determines that the engine 1 is in the cold operation state when the coolant temperature of the engine 1 detected by the water temperature sensor 50 is less than the predetermined water temperature. The predetermined water temperature is such that the temperature of the hydraulic oil supplied to the valve timing switching mechanism 56 via the hydraulic oil control valve 46 is low and the viscosity thereof is high, so that the valve timing switching mechanism 56 may not operate satisfactorily. Is obtained and set in advance based on a predetermined temperature which is the upper limit of the temperature. Therefore, if the detected value of the water temperature sensor 50 is less than the predetermined water temperature, the ECU 48 proceeds to step S2 assuming that the temperature of the hydraulic oil has not reached the predetermined temperature.

  In step S2, the ECU 48 ends the control cycle by controlling the hydraulic oil control valve 46 so that the hydraulic oil is not supplied to the valve timing switching mechanism 56 in order to select the first cam 72 as a cam for driving the exhaust valve 78. To do. In the valve timing switching mechanism 56, the operating oil 92 is not supplied, so that the operating piston 92 of the first rocker arm 58 is positioned below the cylinder portion 90 as described above. For this reason, since the engaging protrusion 106 of the second rocker arm 60 enters the deep groove portion 100 of the operating piston 92, the engaging protrusion 106 does not contact the operating piston 92 in the swinging direction, and the second rocker arm 60 does not swing. The movement is not transmitted to the first rocker arm 58. Accordingly, the first rocker arm 58 is driven by the first cam 72, and the exhaust valve 78 is opened and closed according to the cam profile of the first cam 72. As a result, as described above, the valve opening start timing of the exhaust valve 78 is delayed to a crank angle of 40 to 70 ° after BDC, and the temperature of the exhaust is raised.

Even after the next control cycle, as long as it is determined in step S1 that the engine 1 is in the cold operation state, the ECU 48 proceeds to step S2, and the exhaust valve 78 is opened and closed by the first cam 72 as described above. As a result, the temperature of the exhaust continues to rise.
When the engine 1 is in a cold operation state, the temperature of the exhaust aftertreatment device 24 is generally lowered, but the upstream oxidation catalyst 32, the SCR catalyst 36, and the downstream oxidation catalyst are increased by such a temperature rise of the exhaust. 38 can be activated at an early stage, and the temperature of the filter 34 can be quickly raised to enable continuous regeneration at an early stage. Moreover, as described above, black smoke is not generated when the exhaust gas temperature is increased.

Further, when the engine 48 is in a cold operation state and the ECU 48 determines that the temperature of the hydraulic oil has not reached the predetermined temperature, the first cam 72 opens and closes the exhaust valve without supplying the hydraulic oil. Therefore, the temperature of the exhaust gas can be raised without causing the operation of the valve timing switching mechanism 56 to become unstable due to the low temperature hydraulic oil.
On the other hand, when the warm-up operation of the engine 1 is performed, the cooling water temperature of the engine 1 increases, and it is determined in step S1 that the detection value of the water temperature sensor 50 is equal to or higher than the predetermined water temperature and the engine 1 is not in the cold operation state. In this case, the ECU 48 determines that the temperature of the hydraulic oil has reached a predetermined temperature that enables stable operation of the valve switching mechanism 56, and advances the process to step S3.

  In step S3, the ECU 48 determines whether or not the exhaust gas temperature Tex detected by the inlet side temperature sensor 44 is equal to or higher than a predetermined temperature Ts. The predetermined temperature Ts is set based on the temperature at which the oxidization catalyst 32 and the post-stage oxidation catalyst 38 including the SCR catalyst 36 can be activated, and the ECU 48 determines that the exhaust temperature Tex is equal to or higher than the predetermined temperature Ts. As a result, it is determined that the exhaust temperature has reached a temperature at which the SCR catalyst 36, the front-stage oxidation catalyst 32, and the rear-stage oxidation catalyst 38 can be activated.

Therefore, if the ECU 48 determines in step S3 that the exhaust gas temperature Tex is lower than the predetermined temperature Ts, the ECU 48 determines that the exhaust gas temperature has not reached a temperature at which each catalyst can be activated, and the process proceeds to step S2. By proceeding and selecting the opening and closing of the exhaust valve 78 by the first cam 72 and ending the control cycle, the temperature of the exhaust is raised as described above.
Even after the next control cycle, after determining that the engine 1 is not in the cold operation state in step S1, the ECU 48 performs the process in step S2 as long as it is determined in step S3 that the exhaust temperature Tex has not reached the predetermined temperature Ts. Then, the exhaust valve 78 is opened and closed by the first cam 72 as described above, so that the temperature of the exhaust gas is continuously increased.

  Therefore, even after the engine 1 leaves the cold operation state, the exhaust temperature does not rise to a temperature at which each of the catalysts can be activated, or the exhaust temperature decreases due to a change in the operation state, so that the respective catalysts can be activated. When the temperature falls below a certain temperature, the exhaust valve 78 is opened and closed by the first cam 72, whereby the temperature of the exhaust is raised, and it is possible to quickly raise the temperature to a temperature at which each of the catalysts can be activated. It becomes.

On the other hand, if it is determined in step S3 that the exhaust gas temperature Tex is equal to or higher than the predetermined temperature Ts, the ECU 48 advances the process to step S4 and detects the engine speed detected by the speed sensor 52 and the accelerator opening sensor 54. It is determined whether or not the vehicle is in a deceleration operation state based on the accelerator opening.
In the deceleration operation state, the engine 1 is in a low load operation state or the fuel injection from the injector 4 is stopped, so that the temperature of the exhaust discharged from the engine 1 decreases. For this reason, the exhaust gas whose temperature has decreased is supplied to the exhaust gas aftertreatment device 24.

Therefore, if it is determined in step S4 that the vehicle is in a decelerating operation state, the ECU 48 determines that the vehicle is in an operation state in which the exhaust temperature decreases, proceeds to step S2, and performs the first cam as described above. The opening / closing of the exhaust valve 78 by 72 is selected, and the control cycle ends.
Even after the next control cycle, it is determined in step S1 that the engine 1 is not in the cold operation state, and in step S3, it is determined that the exhaust temperature Tex is equal to or higher than the predetermined temperature Ts, and then the vehicle is decelerated in step S4. As long as it is determined to be in the state, the ECU 48 proceeds to step S2, and the exhaust valve 78 is opened and closed by the first cam 72 as described above.

  When the opening / closing of the exhaust valve 78 by the cam 72 is selected, the valve opening start timing of the exhaust valve 78 is delayed as described above, so that the inside of the cylinder is compared with the case where the exhaust valve 78 is opened / closed by the second cam 82. The amount of residual gas increases, and the amount of fresh air sucked into the cylinder correspondingly decreases. Therefore, the amount of exhaust gas supplied to the exhaust aftertreatment device 24 is reduced, and a decrease in the temperature of the exhaust aftertreatment device 24 can be suppressed.

In addition, since the opening timing of the exhaust valve is delayed by selecting the opening and closing of the exhaust valve 78 by the first cam 72 during the deceleration operation in this way, the pumping loss increases due to the piston compressing the gas in the cylinder. To do. Therefore, an engine braking effect due to an increase in pumping loss can be obtained during deceleration operation.
On the other hand, if it is determined in step S4 that the vehicle is not in the decelerating operation state, the ECU 48 advances the process to step S5, selects opening / closing of the exhaust valve 78 by the second cam 82, and ends the control cycle. Therefore, the exhaust gas temperature is not raised by delaying the opening start timing of the exhaust valve 78 as described above, and the normal operation of the engine 1 is performed.

  As described above, the ECU 48 performs the exhaust gas temperature raising control so that the exhaust valve 78 is opened and closed by the first cam 72 during the cold operation of the engine 1 or when the exhaust gas temperature Tex has not reached the predetermined temperature Ts. Thus, the exhaust gas temperature can be quickly raised by retarding the valve opening start timing of the exhaust valve 78. In particular, during the cold operation of the engine 1, the temperature of the hydraulic oil for the valve timing switching mechanism 56 is low and the viscosity increases, which may hinder stable operation of the valve timing switching mechanism 56. Until it is determined that the coolant temperature detected by the water temperature sensor 50 is equal to or higher than the predetermined temperature and the temperature of the hydraulic oil has risen above the predetermined temperature, the exhaust valve 78 is opened and closed by the first cam 72 and the exhaust valve is discharged from the second cam 82 Since the switching of the valve 78 to the opening / closing operation is prohibited and the supply of hydraulic oil is not required when the exhaust valve 78 is opened / closed by the first cam 72, the valve timing switching mechanism 56 operates stably even during the cold operation of the engine 1. Can be made.

  Further, when the exhaust valve 78 is opened and closed by the first cam 72 as described above during the cold operation of the engine 1, as described above, a part of the valve opening period of the exhaust valve 78 is the intake valve. Since the exhaust valve 78 continues to be opened until it overlaps with the valve opening period, and the supply of fresh air into the cylinder is not greatly hindered by the residual gas, the intake amount of fresh air is greatly increased. It will never decrease. Therefore, even when the engine 1 shifts to the high load operation state in such a state, the temperature of the exhaust does not rise excessively.

Further, the exhaust valve 78 is opened and closed by the first cam 72 even during deceleration operation of the vehicle, and the opening start timing of the exhaust valve 78 is retarded, whereby the amount of exhaust gas supplied to the exhaust aftertreatment device 24. As a result, the temperature drop of the exhaust aftertreatment device 24 can be suppressed, and the engine braking effect can be obtained.
Although the description about the control apparatus of the diesel engine which concerns on one Embodiment of this invention is finished above, this invention is not limited to the said embodiment.

  For example, in the above embodiment, the exhaust post-treatment device 24 including the front-stage oxidation catalyst 32, the filter 34, the SCR catalyst 36, and the rear-stage oxidation catalyst 38 is used. However, the configuration of the exhaust post-treatment device 24 is limited to this. However, the present invention can be applied to any diesel engine having an exhaust aftertreatment device that can be changed as necessary and that may not sufficiently perform the exhaust purification function due to a decrease in exhaust temperature. It is possible to obtain the same effect.

  In the above embodiment, the first rocker arm 58 driven by the first cam 72 and the second rocker arm 60 driven by the second cam 82 are used as the valve timing switching mechanism 56, and Although the opening / closing timing of the exhaust valve 78 is changed by switching the transmission of rocking to the rocker arm 58 and the blocking of the transmission, the configuration of the valve timing switching mechanism 56 is not limited to this, and the present invention is not limited thereto. Any configuration may be used as long as the first switching timing and the second switching timing can be switched.

  Further, in the above embodiment, the cold operation state of the engine 1 is determined based on the cooling water temperature of the engine 1 detected by the water temperature sensor 50, but the method for determining the cold operation state is limited to this. Instead, for example, the determination may be made based on the temperature of the hydraulic oil used in the valve timing switching mechanism 56 or the temperature of the cylinder block of the engine 1.

It is a block diagram of the control apparatus of the diesel engine which concerns on one Embodiment of this invention. It is a figure which shows the assembly | attachment of the 1st rocker arm which comprises a valve timing switching mechanism, and a 2nd rocker arm. It is a top view of a valve timing switching mechanism. It is a figure which shows the assembly | attachment state of a 2nd rocker arm. It is a fragmentary sectional view of a valve timing switching mechanism, and is a figure showing the non-driving state of an operation piston. It is a fragmentary sectional view of a valve timing switching mechanism, and is a figure showing the drive state of an operation piston. It is a figure which shows the relationship between the valve lift amount and opening / closing timing of the exhaust valve by a 1st cam and a 2nd cam. 2 is a graph showing changes in the excess air ratio and the exhaust temperature with the delay of the valve opening start timing of the exhaust valve that is opened and closed by the first cam in the control device of FIG. 1. In the comparative example which is a prior art, it is a graph which respectively shows the change of the excess air ratio and exhaust temperature with the delay of the valve opening start timing of an exhaust valve. It is a flowchart of the exhaust gas temperature raising control which ECU by the control apparatus of FIG.

Explanation of symbols

1 diesel engine 24 exhaust aftertreatment device 48 ECU (control means)
56 Valve timing switching mechanism 78 Exhaust valve

Claims (5)

A part of the opening period of the exhaust valve of the diesel engine overlaps with the opening period of the intake valve of the same cylinder as the exhaust valve, and the opening start timing of the exhaust valve is lower than the piston dead in the expansion stroke of the cylinder. And a part of the opening period of the exhaust valve overlaps with the opening period of the intake valve of the cylinder, and the opening start time of the exhaust valve A valve timing switching mechanism that can be selectively switched to any one of a second opening and closing timing that is an advance side of the opening and closing timing of the one opening and closing timing;
An exhaust aftertreatment device for purifying exhaust discharged from the diesel engine;
Control means for controlling the valve timing switching mechanism so that the exhaust valve opens and closes at the first opening / closing timing during a predetermined cold operation of the diesel engine. .   2. The diesel engine control device according to claim 1, wherein the valve opening start timing of the exhaust valve at the first opening / closing timing is set to 40 to 70 ° as a crank angle after the bottom dead center of the piston.   The valve timing switching mechanism sets the opening / closing timing of the exhaust valve to the second opening / closing timing when the hydraulic oil is supplied, and sets the opening / closing timing of the exhaust valve to the first opening / closing timing when the hydraulic oil is not supplied. The control device for a diesel engine according to claim 1, wherein the timing is set.   The control means controls the valve timing switching mechanism so that the opening / closing timing of the exhaust valve is set to the first opening / closing timing until it determines that the temperature of the hydraulic oil has risen above a predetermined temperature. 4. The diesel engine control device according to claim 3, wherein the valve timing switching mechanism prohibits switching of the opening / closing timing of the exhaust valve from the first opening / closing timing to the second opening / closing timing. 5.   When the control means determines that the diesel engine is in an operation state set in advance as an operation state that causes a decrease in the exhaust gas temperature, the valve timing is set so that the opening / closing timing of the exhaust valve is the first opening / closing timing. The diesel engine control apparatus according to claim 1, wherein the switching mechanism is controlled.

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