JP5575284B2 - Engine exhaust energy recovery method - Google Patents

Description

  The present invention relates to an exhaust energy recovery method that recovers exhaust energy of exhaust gas (combustion gas) discharged from an engine main body such as a marine diesel engine and an onshore generator diesel engine as power.

  As an exhaust energy recovery device that recovers exhaust energy contained in exhaust gas (combustion gas) as power, for example, a supercharger and a power turbine disclosed in Patent Literature are known.

JP-A-63-186916

  In a diesel engine equipped with a device that recovers exhaust energy by directing exhaust gas (combustion gas) discharged from the engine body to a power turbine or the like as well as a supercharger, a part of the exhaust gas Because exhaust energy is not used to drive the turbocharger, depending on the engine operating conditions, the turbocharger efficiency may be reduced, and the scavenging (supply) pressure from the turbocharger to the engine body will be insufficient, resulting in engine combustion efficiency. The fuel consumption rate increases.

  However, in recent years, the shape of the blades of the compressor unit driven by the rotational driving force of the exhaust turbine unit and the turbine unit of the turbocharger, the reduction of the gap with the housing containing the blades, the driving resistance of the turbine unit and the compressor unit The performance of the turbocharger has improved due to improvements such as reduction, and even if the exhaust gas from the engine is led to the power turbine more than before, the turbocharger supplies sufficient scavenging pressure (supply pressure) to the engine body It became possible to do.

As a result, when the diesel engine disclosed in the above-mentioned patent document is operated at a high load, if the bypass valve is throttled (that is, the output of the power turbine is reduced), the exhaust gas used to drive the power turbine is used. Gas is supplied to the exhaust turbine of the supercharger, the driving force and the rotational speed of the exhaust turbine are increased, and the rotational speed of the compressor driven by the exhaust turbine is also increased.
As a result, the pressure of the compressed air supplied from the compressor to the diesel engine (scavenging pressure: supply air pressure) exceeds the allowable operating pressure of the engine, so that the scavenging pressure is less than the allowable pressure from the viewpoint of engine safety. Therefore, the engine is not operated in the optimum operating state, and it does not improve the thermal efficiency.

The present invention has been made in view of the above circumstances, and an engine exhaust energy recovery method that can always ensure an optimal operating state in which engine performance (fuel consumption rate) is optimal with respect to engine load and engine speed. The purpose is to provide.
It is another object of the present invention to maintain the optimum operating state of the engine even when the compression pressure in the cylinder decreases due to aging.

The reference invention of the present invention includes a step of driving an engine, a step of pumping outside air to the engine main body by driving an exhaust turbine supercharger by exhaust gas discharged from the engine, and an exhaust discharged from the engine. An operation method of an engine exhaust energy recovery apparatus comprising: extracting a part of gas and generating electric power by driving a power turbine with the extracted exhaust gas,
Adjusting the flow rate of the exhaust gas flowing into the power turbine by a gas inlet control valve that throttles the flow rate of the extracted exhaust gas; and installing one of the extracted exhaust gases installed upstream of the gas inlet control valve. And a step of adjusting a flow rate of exhaust gas that bypasses the power turbine by an exhaust gas bypass control valve installed in the bypass pipe, and bypassing the part to the downstream side of the power turbine In the method
Detecting engine load, engine speed, and engine scavenging pressure;
Calculating the optimum scavenging pressure of the engine with the lowest fuel consumption rate of the engine from the detected engine load and engine speed;
Calculating the opening correction amount of the exhaust gas bypass control valve based on the difference after obtaining the difference between the detected scavenging pressure of the engine and the calculated optimal scavenging pressure of the engine;
And a step of determining an opening command value of the exhaust gas bypass control valve from the calculated opening correction amount of the exhaust gas bypass control valve.

Optimal According to the engine exhaust energy recovery method according to the present reference invention, the engine load, to calculate the optimum scavenging pressure of the engine to the detected value of an engine rotational speed to the optimum operating condition of the engine, which is the calculated By controlling the exhaust gas bypass amount by controlling the exhaust gas bypass control valve provided in front of the power turbine so that the scavenging pressure is reached, the engine running cost can be reduced by constantly maintaining the engine in the optimum operating state and reducing the fuel consumption rate. It has a good effect on reduction and the environmental improvement accompanying it.

Another reference invention includes a step of driving the engine, a step of driving the exhaust turbine supercharger by the exhaust gas discharged from the engine, and pumping outside air to the engine body, and the exhaust is discharged from the engine. Extracting a part of the exhaust gas, and generating electric power by driving a power turbine with the extracted exhaust gas, and an operating method of the engine exhaust energy recovery apparatus comprising:
Adjusting the flow rate of the exhaust gas flowing into the power turbine by a gas inlet control valve that throttles the flow rate of the extracted exhaust gas; and installing one of the extracted exhaust gases installed upstream of the gas inlet control valve. And a step of adjusting a flow rate of exhaust gas that bypasses the power turbine by an exhaust gas bypass control valve installed in the bypass pipe, and bypassing the part to the downstream side of the power turbine In the method
Detecting engine load, engine speed, and engine scavenging pressure;
Calculating the optimum scavenging pressure of the engine with the lowest fuel consumption rate of the engine from the detected engine load and engine speed;
Calculating the opening correction amount of the exhaust gas bypass control valve based on the difference after obtaining the difference between the detected scavenging pressure of the engine and the calculated optimal scavenging pressure of the engine;
Determining an opening command value of the exhaust gas bypass control valve from the calculated opening correction amount of the exhaust gas bypass control valve;
Changing the opening degree of the exhaust gas bypass control valve based on the determined opening degree command value of the exhaust gas bypass control valve, and
A step of detecting the opening of the changed exhaust gas bypass control valve;
Calculating an error between the determined opening command value of the exhaust gas bypass control valve and the detected opening of the exhaust gas bypass control valve;
Feeding back the calculated error to an opening command value of the exhaust gas bypass control valve.

  By detecting the opening of the exhaust gas bypass control valve and performing feedback control, it is possible to correct the deviation between the specified value and the actual opening due to aging deterioration, etc., and prevent the operating conditions from deviating from the optimal operating conditions. it can.

In another reference invention, preferably, in the step of calculating the error, when the determined opening command value of the exhaust gas bypass control valve matches the opening of the exhaust gas bypass control valve, The scavenging pressure may include a step of maintaining an optimum scavenging pressure of the engine at which the fuel consumption rate of the engine is minimized.

The present invention achieves the above object, and includes a step of driving the engine, a step of driving the exhaust turbine supercharger by exhaust gas discharged from the engine, and pumping outside air to the engine body, Extracting a part of the exhaust gas discharged, and generating electric power by driving a power turbine with the extracted exhaust gas, and an operating method of an engine exhaust energy recovery apparatus comprising:
Adjusting the flow rate of the extracted exhaust gas flowing into the power turbine by a gas inlet control valve that throttles the flow rate of the extracted exhaust gas; and installing the extracted gas upstream of the gas inlet control valve. A bypass pipe that bypasses a part of the exhaust gas to the downstream side of the power turbine, and a step of adjusting a flow rate of the exhaust gas that bypasses the power turbine by an exhaust gas bypass control valve installed in the bypass pipe. In the engine exhaust energy recovery method,
Detecting engine load, engine speed, engine scavenging pressure, and engine cylinder pressure;
Calculating a cylinder compression pressure from the detected cylinder pressure of the engine;
Calculating an optimum in-cylinder compression pressure at which the fuel consumption rate of the engine is the smallest from the detected engine load and engine speed;
Calculating a change amount of the exhaust valve closing timing based on the difference after calculating the difference between the calculated in-cylinder compression pressure and the calculated in-cylinder optimum compression pressure;
Determining the exhaust valve closing timing from the calculated exhaust valve closing timing change amount;
Changing the exhaust valve closing timing based on the determined exhaust valve closing timing,
A step of detecting the in-cylinder compression pressure of the engine after changing the exhaust valve closing timing;
Calculating an error between the in-cylinder compression pressure of the engine after changing the detected exhaust valve closing timing and the optimum in-cylinder compression pressure;
Feeding back the calculated error to the exhaust valve closing timing command value;
It is provided with.
As a result, the engine can maintain a more finely-tuned optimum operation (the fuel consumption rate is the smallest), and the fuel consumption rate can be further improved and the environmental load can be reduced.

The present invention also includes a step of driving the engine, a step of pumping outside air to the engine body by driving an exhaust turbine supercharger by exhaust gas discharged from the engine, and an exhaust gas discharged from the engine. And a step of generating electric power by driving a power turbine with the extracted exhaust gas, and an operation method of an engine exhaust energy recovery apparatus comprising:
Adjusting the flow rate of the extracted exhaust gas flowing into the power turbine by a gas inlet control valve that throttles the flow rate of the extracted exhaust gas; and installing the extracted gas upstream of the gas inlet control valve. A bypass pipe that bypasses a part of the exhaust gas to the downstream side of the power turbine, and a step of adjusting a flow rate of the exhaust gas that bypasses the power turbine by an exhaust gas bypass control valve installed in the bypass pipe. In the engine exhaust energy recovery method,
Detecting engine load, engine speed, engine scavenging pressure, and engine cylinder pressure;
Calculating a maximum cylinder pressure from the detected cylinder pressure of the engine;
Calculating an optimum maximum pressure in the cylinder that minimizes the fuel consumption rate of the engine from the detected engine load and engine speed;
Calculating a change amount of the fuel injection timing based on the difference between the calculated maximum pressure in the cylinder and the calculated optimal maximum pressure in the cylinder; and
Determining the fuel injection timing from the calculated change amount of the fuel injection timing;
Changing the fuel injection timing based on the determined fuel injection timing,
A step of detecting the maximum pressure in the cylinder of the engine after changing the fuel injection timing;
Calculating an error between the maximum in-cylinder pressure of the engine after changing the detected fuel injection timing and the optimal maximum pressure in the cylinder;
Feeding back the calculated error to the fuel injection timing command value.
As a result, the engine can maintain a more finely-tuned optimum operation (the fuel consumption rate is the smallest), and the fuel consumption rate can be further improved and the environmental load can be reduced.

The present invention also includes a step of driving the engine, a step of pumping outside air to the engine body by driving an exhaust turbine supercharger by exhaust gas discharged from the engine, and an exhaust gas discharged from the engine. And a step of generating electric power by driving a power turbine with the extracted exhaust gas, and an operation method of an engine exhaust energy recovery apparatus comprising:
Adjusting the flow rate of the extracted exhaust gas flowing into the power turbine by a gas inlet control valve that throttles the flow rate of the extracted exhaust gas; and installing the extracted gas upstream of the gas inlet control valve. A bypass pipe that bypasses a part of the exhaust gas to the downstream side of the power turbine, and a step of adjusting a flow rate of the exhaust gas that bypasses the power turbine by an exhaust gas bypass control valve installed in the bypass pipe. In the engine exhaust energy recovery method,
Detecting engine load, engine speed, engine scavenging pressure, and engine cylinder pressure;
Calculating a cylinder compression pressure and a cylinder maximum pressure from the detected cylinder pressure of the engine;
Calculating the optimum compression pressure in the cylinder that minimizes the fuel consumption rate of the engine and the optimum maximum pressure in the cylinder from the detected engine load and engine speed;
Calculating the opening correction amount of the exhaust gas bypass control valve based on the difference after obtaining the difference between the calculated in-cylinder compression pressure and the optimum compression pressure in the cylinder;
Determining an opening command value of the exhaust gas bypass control valve from the calculated opening correction amount of the exhaust gas bypass control valve;
Changing the opening degree of the exhaust gas bypass control valve based on the determined opening degree command value of the exhaust gas bypass control valve, and
A step of detecting the in-cylinder compression pressure of the engine after changing the opening of the exhaust gas bypass control valve;
Calculating an error between the in-cylinder compression pressure of the engine after changing the detected opening degree of the exhaust gas bypass control valve and the optimum compression pressure in the cylinder;
Determining whether or not the changed opening of the exhaust gas bypass valve is fully closed, and determining the engine exhaust valve closing timing based on the calculated error in the case of full closing;
Determining fuel injection timing of the engine based on a difference between the maximum pressure in the cylinder and the optimal maximum pressure in the cylinder;
Changing the engine exhaust valve closing timing and the determined engine fuel injection timing based on the determined engine exhaust valve closing timing and the determined engine fuel injection timing. It is characterized by that.

If the scavenging pressure decreases due to a difference between the exhaust gas bypass control valve command value and the actual valve opening due to deterioration over time, or if the exhaust valve seat is worn, the compression pressure will decrease and the engine performance will decrease. To do. By directly detecting the combustion pressure in the cylinder and controlling the exhaust gas bypass control valve so that the compression pressure Pcomp in the cylinder becomes a predetermined value, the actual operating conditions of the engine are prevented from deviating from the optimum operation due to secular change. can do.
As a result, the engine can maintain a more finely-tuned optimum operation (the fuel consumption rate is the smallest), and the fuel consumption rate can be further improved and the environmental load can be reduced.

  Further, the cylinder internal pressure [compression pressure Pcomp and maximum pressure (combustion pressure) Pmax] is directly detected, and the detected compression pressure Pcomp and maximum pressure (combustion pressure) Pmax respectively indicate that the engine operating state is relative to the engine load. By controlling the exhaust gas bypass control valve opening, fuel injection timing, and exhaust valve closing timing so that the map's optimal operating state value is reached, the engine's optimal operation (the fuel consumption rate is the highest) even if the fuel properties change. Less operation).

  Even when the opening degree of the exhaust gas bypass control valve is fully closed, the in-cylinder compression pressure Pcomp can be controlled to the optimum compression pressure Pcomp0 by controlling the exhaust valve closing timing. It can be done reliably.

Preferably, in the present invention, a step of detecting an in-cylinder compression pressure and a maximum in-cylinder pressure after changing an engine exhaust valve closing timing and an engine fuel injection timing;
If there is an error between the calculated optimum maximum pressure in the cylinder, the exhaust valve closing timing of the engine, and the maximum pressure in the cylinder after changing the fuel injection timing of the engine, the fuel valve injection is performed based on the error. Determining a timing correction amount and determining a fuel injection timing by feeding back the fuel valve injection timing correction amount; and
If there is an error between the calculated optimum compression pressure in the cylinder and the exhaust valve closing timing of the engine and the compression pressure in the cylinder after changing the fuel injection timing of the engine, the exhaust valve closing timing is based on the error. Determining an exhaust valve closing timing by determining a correction amount and feeding back the exhaust valve closing timing correction amount.

According to the exhaust energy recovery method of the present invention, engine performance (fuel consumption rate) is maintained at an optimum state based on detection values from an engine load detection means, an engine speed detection means, a scavenging pressure detection means, and the like. it can.

FIG. 1 is a schematic configuration diagram of an exhaust energy recovery apparatus to which an exhaust energy recovery method of the present invention is applied . Is an example of a control database for determining the optimum operating state of the present invention. FIG. 3 is a control configuration diagram according to a first reference example of the present invention. These are the control flowcharts concerning the 1st reference example of the present invention. These are the control block diagrams which concern on the 2nd reference example of this invention. These are the control flowcharts concerning the 2nd reference example of the present invention. FIG. 3 is a control configuration diagram according to the first embodiment of the present invention. These are the control flowcharts concerning 1st Embodiment of this invention. These are the control flowcharts concerning 2nd Embodiment of this invention.

Hereinafter, an embodiment of an engine exhaust energy recovery device according to the present invention will be described.
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.

  As shown in FIG. 1, a marine diesel engine 1 includes a diesel engine main body (for example, a low-speed two-cycle diesel engine) 2, a diesel engine main body 2 (hereinafter referred to as “engine main body”), an exhaust manifold 7, And a cylinder 6 in which fuel injected by a fuel injection device (not shown) is combusted (in the case of this embodiment, a 6-cylinder engine in which 6 cylinders are arranged is shown). 3 is an exhaust turbine section 3a driven by the exhaust gas discharged from the exhaust manifold 7, and is coaxially coupled to the exhaust turbine section 3a to be driven to rotate, and the outside air is scavenged (supplied) into the engine body 2 to increase the pressure. An exhaust turbine supercharger L1 connected to the exhaust manifold 7 and the exhaust turbine section 3a, and a first exhaust pipe 18 through which exhaust gas is sent to the exhaust turbine section 3a. Is an intercooler for cooling the scavenging air (supply air) compressed by the compressor unit 3b to increase the air density, K1 is a first air supply pipe connecting the compressor unit 3b and the intercooler 18, and K2 is an intercooler 18. Are connected to the air supply manifold 8 of the engine body 2, and the scavenged air (air supply) cooled by the intercooler 18 is supplied to the air supply manifold 8 of the engine body 2. The second feed pipe to pass.

  Reference numeral 4 denotes a power turbine that is driven by exhaust gas diverted from the exhaust manifold 7 and is a drive source of a generator that will be described later. Reference numeral 9 denotes exhaust gas that drives the power turbine 4 and the exhaust turbine section 3a of the exhaust turbine supercharger 3, respectively. A heat exchanger L10 that heat-exchanges water into steam by heat is a water supply pipe that supplies water to the heat exchanger 9. The heat exchanger 9 is a device that passes water supplied through the water supply pipe L10 through an evaporation pipe (not shown), and converts the water into steam by the heat of the exhaust gas.

L2 is a second exhaust pipe that connects the exhaust manifold 7 and the power turbine 4 and sends exhaust gas to the power turbine 4, and L3 connects the power turbine 4 and the heat exchanger 9, and is discharged from the power turbine 4. The third exhaust pipe L4 for passing the exhaust gas to the heat exchanger 9 is connected to the exhaust turbine section 3a and the third exhaust pipe L3 of the exhaust turbine supercharger 3, and the exhaust gas from the exhaust turbine section 3a is The fourth exhaust pipe L5 that is passed to the heat exchanger 9 is connected to the steam turbine 5 and the heat exchanger 9 as a driving source of the generator in cooperation with the power turbine 4 described above. A fifth exhaust pipe for passing the heat-exchanged steam to the steam turbine 5, L6 is a sixth exhaust pipe for returning the steam that has driven the steam turbine 5 to a condenser (condenser) (not shown), and L7 is a heat exchanger. In step 9, the exhaust gas obtained by exchanging water with steam is A seventh exhaust pipe to be discharged overboard through feeding the panel (chimney) (not shown).
The water condensed by condensing steam with a condenser (condenser) is supplied to the heat exchanger 9 through a water supply pipe L10.

  V1 is interposed in the middle of the second exhaust pipe L2, and a gas inlet control valve whose opening is adjusted by a controller (not shown) to control the exhaust gas flow rate to the power turbine 4, V2 is the fifth exhaust A steam flow rate adjusting valve which is interposed in the middle of the pipe L5 and whose opening degree is adjusted by the controller described above, and V3 is a position upstream of the gas inlet control valve V1 of the second exhaust pipe L2; An exhaust gas bypass control valve interposed in the middle of the first bypass pipe L8 connecting the third exhaust pipe L3, V4 is a position upstream of the flow rate adjusting valve V2 of the fifth exhaust pipe L5, and the sixth exhaust pipe L6. Is a steam bypass flow rate control valve interposed in the middle of the second bypass pipe L11.

  V5 is an emergency control valve for emergency which is interposed in the second exhaust pipe L2 between the coupling part of the second exhaust pipe L2 and the first bypass pipe L8 and the gas inlet control valve V1, and in any situation It is activated when it is desired to stop the exhaust gas flow into the power turbine 4.

  An orifice 19 is interposed in the middle of the exhaust gas bypass control valve V3 and the third exhaust pipe L3. The orifice 19 is operated when the engine body 2 is in a high load operation (normal navigation operation) and the power turbine 4 is in a full load operation state (that is, the exhaust gas bypass control valve V3 is fully closed and the gas inlet control valve V1 is When the gas inlet control valve V1 is fully closed (when the power turbine 4 is stopped), the exhaust gas bypass control valve V3 supplies the same amount of exhaust gas flowing through the gas inlet control valve V1 when the gas inlet control valve V1 is fully opened. Has been adjusted to flow.

Therefore, when the power turbine 4 is in a stopped state while the engine body 2 is operating at a high load, the flow rate of the exhaust gas supplied to the exhaust turbine supercharger 3 side increases, and the scavenging pressure increases beyond a predetermined level. To prevent the engine from being adversely affected.
On the other hand, as described above, the orifice 19 has the same amount of exhaust gas as the exhaust gas flowing through the power turbine 4 when the engine body 2 is operated at high load (normal navigation operation) and the power turbine 4 is at full load operation. Is adjusted such that when the gas inlet control valve V1 is fully closed, the exhaust gas flowing through the orifice 19 is exhausted from the exhaust turbine supercharger. Since the flow rate of the exhaust gas supplied to the third side does not flow so as to decrease, it is possible to prevent the scavenging pressure of the exhaust turbine supercharger 3 from becoming a predetermined value or less and to ensure the optimum operation of the engine body 2.

A rotating shaft (not shown) of the power turbine 4 and a rotating shaft (not shown) of the steam turbine 5 are connected via a speed reducer (not shown) and a coupling 10, and further, a rotating shaft (not shown) of the steam turbine 5. (Not shown) and the rotating shaft (not shown) of the generator 11 are connected via a speed reducer (not shown) and the coupling 12.
Further, the generator 11 is electrically connected to a switchboard 14 separately installed in the ship (in this embodiment, the engine room) via the control resistor 13, and the power generated by the generator 11 is used as the ship power. It can be used now.

Next, a map that is a control database that determines the optimum operating state based on the fuel consumption rate in the embodiment of the present invention will be described with reference to FIG.
The control database in FIG. 2 is a marine two-cycle engine, and shows a relationship at a certain engine speed and load. Therefore, a map having the same relationship with each of the engine speed and the load is provided.
The horizontal axis indicates the compression pressure Pcomp, and the right direction in FIG. The vertical axis indicates the fuel injection timing, the upper part indicates the timing retard direction, and the lower part indicates the advance direction.
In place of the compression pressure Pcomp, scavenging (supply) pressure (relationship that the compression pressure increases when the scavenging pressure is high), exhaust valve closing timing of the engine body (relationship that increases the compression pressure by quickly closing) The same relationship can be obtained even if the control factor is changed.
In the figure, a plurality of curves with intervals are contours of the fuel consumption rate, and the positions and shapes of the curves differ depending on the engine speed and load. The contour line of the fuel consumption rate in the figure shows that the fuel consumption rate is better as it moves in the lower right direction (center direction of the curve) of the curve.

The thick straight line indicates the in-cylinder maximum pressure Pmax upper limit value, and the area on the right side of the in-cylinder maximum pressure Pmax upper limit value exceeds the allowable pressure of the engine body, and is in an unusable range.
Therefore, the target position (optimum operation point) for controlling the fuel consumption rate of the engine to the best optimum operating state is the left side area of the in-cylinder maximum pressure Pmax upper limit value, and the in-cylinder maximum pressure Pmax upper limit value of the contour line of the fuel consumption rate It becomes a part close to.
Based on this target position, the scavenging pressure, the exhaust valve closing timing, and the fuel injection timing are controlled to maintain the optimum operating state of the engine.

Also, as the load decreases, the scavenging pressure decreases and the compression pressure decreases accordingly, so that the fuel injection timing can be advanced. Therefore, as the load is lower, the optimum operation point in the map of FIG. 2 moves in the lower left direction along a thick straight in-cylinder maximum pressure Pmax upper limit value.
At that time, the contour line of the fuel consumption rate and the center of the curve move in the lower left direction along the upper cylinder maximum pressure Pmax upper limit value with a thick straight line.

(First Reference Example )
A first reference example of an engine optimal operation (lowest fuel consumption rate) control method according to the present invention will be described with reference to FIGS. Figure 3 is the control block diagram according to the first exemplary embodiment of the present invention, FIG. 4 is a control flowchart according to the first exemplary embodiment of the present invention.
In FIG. 3, a signal from the engine load detecting means 20, a signal from the engine speed detecting means 21, and a signal from the scavenging pressure detecting means 22 for detecting the scavenging (supply air) pressure of the engine are control devices. An exhaust gas bypass control valve control command signal A input to the controller 23 and output to the exhaust gas bypass control valve V3 is output.

As shown in FIG. 4, in step S1, the controller 23 detects the engine load L, the engine speed Ne, and the scavenging pressure Ps from the engine body 1 by the respective detection means.
Input as a signal. In step S2, the controller 23 compares the engine load L and the engine speed Ne with a database prepared in the controller 23 in advance to calculate the optimum scavenging pressure Ps0 (based on the map in which the horizontal axis indicates the scavenging pressure in FIG. 2). Calculated).
Next, in step S3, the controller 23 obtains a difference ΔPs between the scavenging pressure Ps and the optimum scavenging pressure Ps0 calculated in step S2, and based on the difference ΔPs, calculates an opening correction amount ΔA of the exhaust gas bypass control valve V3. decide.

  Next, in step S4, a new control valve opening command value A for the exhaust gas bypass control valve V3 is calculated from the opening correction amount ΔA of the exhaust gas bypass control valve V3 determined in step S3 and the current opening command value A ′. To decide. In step S5, the controller 23 outputs a command for controlling the exhaust gas bypass control valve V3 to a new control valve opening command value A by the controller 23. Thereafter, the process returns from step S5 to step S1 and is repeated. By repeating this operation, it is checked whether the scavenging pressure Ps is in a state for maintaining the optimum operating state, and deviating from the optimum scavenging pressure Ps0 for maintaining the optimum operating state (the lowest fuel consumption rate). If so, correct it.

According to the first reference example , the control device 23 calculates the optimum scavenging pressure Ps0 for the engine to bring the engine into an optimum operating state from the detected engine load and the detected value such as the engine speed, and the calculation. The amount of exhaust gas to be diverted to the power turbine side so as to be the same scavenging pressure is controlled to the optimum scavenging pressure by the control of the exhaust gas bypass control valve V3, and the engine is always maintained in the optimum operating state, By suppressing the fuel consumption rate, it is possible to obtain a good effect for reducing the running cost of the engine and the accompanying environmental load.

(Second reference example )
Next, a second reference example of the engine optimum operation control method according to the present invention will be described with reference to FIGS. The first and second reference examples are cases of control based on the detected value of the scavenging pressure (supply pressure) without measuring the cylinder internal pressure. Embodiments 1 and 2 described later indicate the cylinder internal pressure. This is the case of measuring and controlling.
FIG. 5 is a control configuration diagram according to the second reference example , and FIG. 6 is a control flowchart according to the second reference example .
In FIG. 5, the same components as those in the first reference example are denoted by the same reference numerals. The configuration different from the first reference example is that an opening degree signal is inputted from the exhaust gas bypass control valve opening degree detecting means 26, and further, a fuel injection timing signal, an exhaust valve closing timing signal, a hydraulic oil pressure-accumulating pressure signal are supplied to the engine controller 25. This is the point at which (hydraulic pressure accumulation pressure of fuel pump drive oil in an electronically controlled engine) or fuel oil pressure accumulation pressure signal (fuel pressure accumulation pressure of common rail type fuel pump) is output.

In the flowchart shown in FIG. 6, first, in step S11, the controller 24 sends the exhaust gas bypass control valve opening degree detection means 26 to the exhaust gas bypass control valve opening degree signal B, the engine load L from the engine body 1, and the engine speed. Ne and scavenging pressure Ps are detected by the respective detection means and input as signals.
Next, in step S12, a map prepared in advance in the controller 24 (optimum scavenging pressure Ps0, fuel injection timing θinj, exhaust valve closing timing θevc, hydraulic oil / fuel oil pressure accumulation map for engine load L and engine speed Ne). ) To calculate the optimum value of each parameter.
That is, the map prepared in advance in the controller 24 is, as shown in FIG. 2, for each engine load L and engine speed Ne, a fuel consumption rate contour line and a fuel consumption rate contour line within the coordinates of the compression pressure Pcomp and the fuel injection timing. This indicates a map in which the P point is set as the optimum operation point by indicating the in-cylinder maximum pressure Pmax upper limit value.
Then, instead of the compression pressure Pcomp on the horizontal axis, scavenging pressure, exhaust valve closing timing, hydraulic oil pressure accumulation (hydraulic pressure accumulation pressure of fuel pump drive oil in an electronically controlled engine), or fuel oil pressure accumulation (common rail fuel) It is good also as fuel accumulation pressure of a pump. Based on these maps, the optimum value of each parameter is calculated.

  In step S13, the controller 24 obtains a difference ΔPs between the scavenging pressure Ps detected by the scavenging pressure detection means 22 and the optimum scavenging pressure Ps0 calculated in step S12, and determines an opening correction amount ΔA based on the ΔPs. In step S14, a new control valve opening A of the exhaust gas bypass control valve V3 is determined from the opening correction amount ΔA of the exhaust gas bypass control valve V3 determined in step S13 and the current opening command value A ′. In step S15, the controller 24 outputs a command for controlling the exhaust gas bypass control valve V3 to a new control valve opening A. In step S16, an error between the detected value B of the newly detected exhaust gas bypass control valve V3 and the command value A is calculated. If there is an error in step S17, the process returns to step S14, a correction amount is calculated based on the error, and the correction is repeated.

When the detected control valve opening B of the exhaust gas bypass control valve V3 becomes as instructed by the command value A, the process returns to step S11 and the control is repeated so that the scavenging pressure Ps maintains the optimum scavenging pressure Ps0.
On the other hand, in step S18, values for maintaining optimum engine operation are transmitted as signals from the fuel injection timing θinj, the exhaust valve closing timing θevc, and the hydraulic oil / fuel oil accumulated pressure map to the engine controller 25, and the engine body 2 The above control is also implemented.

That is, the above-mentioned manner in place of the compression pressure P _C of the horizontal axis in FIG. 2, the scavenging pressure, exhaust valve closing timing, the hydraulic fluid accumulator pressure (hydraulic oil accumulation pressure of the fuel pump driving fluid in the electronic control engine), or, The fuel injection timing on the vertical axis and the exhaust valve on the horizontal axis with respect to the position where the optimum operating point P with the lowest fuel consumption rate is set according to the map of the fuel oil pressure (the fuel pressure of the common rail fuel pump) The optimum values of the closing timing, hydraulic oil pressure and fuel oil pressure are calculated and output.

  The hydraulic oil accumulation pressure of the fuel pump driving oil in the electronically controlled engine, the fuel accumulation pressure of the common rail fuel pump, and the closing timing of the exhaust valve directly affect the fuel injection pressure. Therefore, it is possible to maintain high hydraulic oil pressure and fuel injection pressure, ensure optimal combustion by miniaturizing fuel in the cylinder and promoting mixing of fuel and air, and reducing fuel consumption rate by improving thermal efficiency. A good effect can be obtained in reducing the environmental load accompanying the purification of exhaust gas by improving combustion.

  Further, as shown in steps S14 to S17 in FIG. 6, the opening degree of the exhaust gas bypass control valve V3 is detected and feedback control is performed to correct a deviation between the specified value and the actual opening degree due to deterioration over time. It is possible to prevent the operating condition from deviating from the optimum operating condition.

(First Embodiment)
Next, a first embodiment of an engine optimum operation control method according to the invention FIG 7 will be described with reference to FIG. FIG. 7 is a control configuration diagram, and FIG. 8 is a control flowchart.
In the control configuration shown in FIG. 7, the same components as those of the second reference example are denoted by the same reference numerals. The configuration different from the second reference example is that a cylinder pressure signal from the cylinder pressure detection means 27 is input to the controller 28.

In the flowchart shown in FIG. 8, first, in step S21, the controller 28 notifies the exhaust gas bypass control valve opening signal B detected from the exhaust gas bypass control valve V3, the engine load L from the engine body 1, the engine speed Ne, In addition to the scavenging pressure Ps, the in-cylinder pressure Pcyl is detected by each detecting means and input as a signal. In step S22, the cylinder compression pressure (pressure before ignition) Pcomp and the cylinder maximum pressure Pmax are calculated from the crank angle history of the detected cylinder pressure Pcyl.
Next, in step S23, the parameter optimum value in light of a map prepared beforehand in the controller 28 (map of engine load L, optimum scavenging pressure Ps0, optimum compression pressure Pcomp0, optimum maximum pressure Pmax0 with respect to engine speed Ne). Is calculated.
In step S24, a difference ΔPs between the scavenging pressure Ps and the optimum scavenging pressure Ps0 calculated in step S23 is obtained, and an opening correction amount ΔA is determined based on ΔPs. In step S25, a new control valve opening A of the exhaust gas bypass control valve V3 is determined from the opening correction amount ΔA of the exhaust gas bypass control valve V3 determined in step S24 and the current opening command value A ′.

In step S26, the controller 28 outputs a command to control to the new control valve opening command value A to the exhaust gas bypass control valve V3 determined in step S25. In step S27, an error between the newly detected value of the exhaust gas bypass control valve V3 and the command value is calculated. In step S28, it is determined whether or not there is an error. If there is an error, a correction amount is calculated based on the error in step S30, the process returns to step S25, and the correction of the opening degree of the exhaust gas bypass control valve V3 is repeated.
When the detected control valve opening A of the exhaust gas bypass control valve V3 becomes as instructed by the command value, the process returns to step S21 and the control is repeated so that the scavenging pressure Ps maintains the optimum scavenging pressure Ps0.

On the other hand, in step S31, the exhaust valve closing timing change amount Δθevc is determined based on the difference ΔPcomp between the cylinder compression pressure Pcomp calculated in step S23 and the optimum compression pressure Pcomp0.
Similarly, in parallel with the determination of the change amount Δθevc of the exhaust valve closing timing in step S32, the change amount Δθinj of the fuel injection timing based on the optimum maximum pressure Pmax0 calculated in step S23 and the maximum cylinder pressure Pmax calculated in step S22. Decide.

In step S33, the exhaust valve closing timing is determined based on the exhaust valve closing timing change amount Δθevc determined in step S31, and in step S34, the fuel injection timing θinj is determined. In step S35, the controller 28 issues a correction command for the exhaust valve closing timing θevc and the fuel injection timing θinj to the engine controller 25. In step S36, an error between the target optimum maximum pressure Pmax0 and optimum compression pressure Pcomp0 and the detected in-cylinder maximum pressure Pmax and in-cylinder compression pressure Pcomp is calculated. If there is an error in step S37, the correction amount is calculated based on the error, and the control is repeated by feeding back to step S33 and step S34, respectively.
As a result, the engine can maintain a more finely-tuned optimum operation (the fuel consumption rate is the smallest), and the fuel consumption rate can be further improved and the environmental load can be reduced.

  The compression pressure compressed in the engine cylinder is determined by two factors, the scavenging pressure and the exhaust valve closing timing. Therefore, by setting the relationship of delaying the exhaust valve closing timing while increasing the scavenging (supply) pressure, the compression work when the piston is raised can be reduced, and the fuel efficiency can be reduced. Further, the cylinder at the compression top dead center can be obtained. Since the internal combustion gas temperature is lowered, NOx (nitrogen oxide) generation during fuel combustion can be suppressed, so that the environmental load can be reduced.

  Further, as shown in steps S24 to S27, by sequentially detecting the change in the scavenging pressure and controlling the opening degree of the exhaust gas bypass control valve so that the scavenging pressure becomes the optimum pressure, the exhaust gas turbocharger side is controlled. By adjusting the amount of exhaust gas, the scavenging pressure to the engine body can be adjusted, and the deviation between the command value and the actual opening due to deterioration over time can be corrected, and the operating conditions deviate from the optimal operating conditions Can be prevented.

In addition, the combustion state of the fuel affects one of the conditions for maintaining the engine in the optimum operating state. The combustion speed of the fuel is affected by the engine speed, engine scavenging (supply air) pressure, fuel properties (cetane number, viscosity, mixing of impurities, etc.), etc., and the combustion speed depends on the timing of fuel ignition, fuel miniaturization, etc. Therefore, as shown in steps S31 to S37, the in-cylinder pressure [compression pressure Pcomp and maximum pressure (combustion pressure) Pmax] is directly detected, and the detected compression pressure Pcomp and maximum pressure (combustion pressure) Pmax are detected. By controlling the exhaust gas bypass control valve opening, fuel injection timing, and exhaust valve closing timing so that the engine operating state becomes the value of the optimal operating state of the map for the engine load, Even when the cylinder pressure decreases due to the change, the optimum operation of the engine (operation with the lowest fuel consumption rate) can be maintained.
Note that the compression pressure Pcomp and the maximum pressure Pmax are not controlled to the optimum values, but the ratio of Pmax / Pcomp is taken and the exhaust gas bypass control valve is controlled so that the optimum map ratio given to the engine load is obtained. It is also possible to do.

( Second Embodiment)
Next, a second embodiment of an engine optimum operation control method according to the invention FIG 7 is described based on FIG. FIG. 7 is a control block diagram, which is the same as in the first embodiment. FIG. 9 shows a control flowchart.
In FIG. 9, first, in step S41, the controller 29 receives the detected value of the exhaust gas bypass control valve V3 in addition to the engine load L, the engine speed Ne, the scavenging pressure Ps, and the cylinder pressure Pcyl from the engine body 1, respectively. Is detected and input as a signal. In step S42, the in-cylinder compression pressure Pcomp and the in-cylinder maximum pressure Pmax are calculated from the crank angle history of the detected in-cylinder pressure Pcyl.
In step S43, an optimal parameter value is calculated in light of a map prepared beforehand in the controller 29 (map of engine load L, optimum compression pressure Pcomp0 and optimum maximum pressure Pmax0 with respect to engine speed Ne).

  In step S44, the controller 29 determines the change amount ΔA of the opening degree of the exhaust gas bypass control valve V3 based on the difference ΔPcomp between the cylinder compression pressure Pcomp and the optimum compression pressure Pcomp0. In step S45, a new control valve opening command value A of the exhaust gas bypass control valve V3 is determined from the opening correction amount ΔA of the exhaust gas bypass control valve V3 determined in step S44 and the current opening command value A ′. . In step S46, in step S45, the controller 29 outputs a command for controlling the exhaust gas bypass control valve V3 to a new control valve opening A.

  In step S47, the optimum compression pressure Pcomp0 is compared with the newly detected in-cylinder compression pressure Pcomp, and the error is calculated. In step S48, it is determined whether the opening degree of the exhaust gas bypass control valve V3 is 0 or open. When the opening degree A ≠ 0 of the exhaust gas bypass control valve V3, that is, when it is open, the opening degree correction amount of the exhaust gas bypass control valve V3 based on the error is calculated in step S49. The opening degree control of the exhaust gas bypass control valve V3 is performed by reflecting the result in step S45. On the other hand, if the opening degree A = 0, that is, the valve is closed in step S48, the exhaust valve closing timing correction amount Δθevc is calculated in step S50 based on the error of the cylinder compression pressure Pcomp. In step S51, the exhaust valve closing timing θevc is determined.

  In step S52, the fuel injection timing change amount Δθinj is determined based on the difference between the maximum cylinder pressure Pmax calculated in step S43 and the optimum maximum pressure Pmax0. In step S53, the fuel injection timing θinj is determined. In step S54, the controller 29 issues a control command for the exhaust valve closing timing θevc determined in step S51 and the fuel injection timing θinj determined in step S53 to the engine controller 25.

In step S55, the difference between the target optimum maximum pressure Pmax0 and optimum compression pressure Pcomp0 and the detected in-cylinder maximum pressure Pmax and in-cylinder compression pressure Pcomp is calculated.
As a result, if there is an error between the maximum cylinder pressure Pmax and the target optimum maximum pressure Pmax0, in step S56, a fuel injection timing change amount Δθinj is calculated based on the error in the cylinder maximum pressure Pmax, and the process returns to step S53. Then, the fuel injection timing θinj is again determined based on the error of Pmax, and a signal is output to the engine controller 25.
On the other hand, if there is an error from the target compression pressure Pcomp0 in the cylinder, the process returns to step S50, and the correction amount of the exhaust valve closing timing θevc is recalculated based on the error from the optimum compression pressure Pcomp0.

If the scavenging pressure decreases due to a difference between the exhaust gas bypass control valve command value and the actual valve opening due to deterioration over time, or if the exhaust valve seat is worn, the compression pressure will decrease and the engine performance will decrease. To do. As shown in steps S44 to S48, the actual operating condition of the engine is aged by directly detecting the combustion pressure in the cylinder and controlling the exhaust gas bypass control valve so that the compression pressure Pcomp in the cylinder becomes a predetermined value. It is possible to prevent deviation from optimal operation due to changes.
As a result, the engine can maintain a more finely-tuned optimum operation (the fuel consumption rate is the smallest), and the fuel consumption rate can be further improved and the environmental load can be reduced.

  Further, the cylinder internal pressure [compression pressure Pcomp and maximum pressure (combustion pressure) Pmax] is directly detected, and the detected compression pressure Pcomp and maximum pressure (combustion pressure) Pmax respectively indicate that the engine operating state is relative to the engine load. By controlling the exhaust gas bypass control valve opening, fuel injection timing, and exhaust valve closing timing so that the map's optimal operating state value is reached, the engine's optimal operation (the fuel consumption rate is the highest) even if the fuel properties change. Less operation).

  In addition, even when the opening degree of the exhaust gas bypass control valve V3 is in the fully closed state, the cylinder compression pressure Pcomp can be controlled to the optimum compression pressure Pcomp0 by controlling the exhaust valve closing timing. Can be performed reliably.

It should be noted that the present invention is not limited to the above-described embodiments, and modifications and changes can be appropriately made as necessary without departing from the technical idea of the present invention.
In the above-described embodiment, the exhaust energy recovery apparatus including one exhaust turbine supercharger 3, one power turbine 4, and one steam turbine 5 has been described as a specific example. However, the present invention is limited to such an example. For example, two exhaust turbine superchargers 3, a power turbine 4 and a power turbine that controls the rotational speed by providing a variable nozzle for adjusting the inflow amount of exhaust gas on the input side of the power turbine are applied. It is also possible to do.

  Further, according to the embodiment of the present invention, the gas inlet control valve V1, the steam flow rate adjusting valve V2, the exhaust gas bypass control valve V3, and the steam bypass flow rate control valve V4 are finely adjusted, so that the power turbine 4 and the steam turbine 5 are controlled. Since each operation can be adjusted steplessly, the adjustment range of the power generation amount of the generator 11 becomes large, so that the capacity of the control resistor 13 is small and miniaturized even if the power consumption in the ship changes greatly. It is advantageous in terms of cost because it can be used.

  In the present invention, the exhaust energy of the engine is connected in series with a power turbine and a steam turbine through a reduction gear and a coupling, and the generator is driven to supply power to the ship, but compressed air is used as a power source for the air actuator. It can also be stored in an air tank.

1 Marine diesel engine 2 Diesel engine body (engine body)
DESCRIPTION OF SYMBOLS 3 Exhaust turbine supercharger 3a Turbine part 3b Compressor part 4 Power turbine 5 Steam turbine 7 Exhaust manifold 8 Supply manifold 9 Heat exchanger 11 Generator 13 Resistor for control 18 Intercooler L1 1st exhaust pipe L2 2nd exhaust pipe L3 3rd exhaust pipe L5 5th exhaust pipe K1 1st air supply pipe K2 2nd air supply pipe V1 Gas inlet control valve V2 Steam flow control valve V3 Exhaust gas bypass control valve V4 Steam bypass flow control valve

Claims (4)

A step of driving the engine, a step of driving the exhaust turbine supercharger by the exhaust gas discharged from the engine, and pumping outside air to the engine body, and a part of the exhaust gas discharged from the engine is extracted. An operation method of an engine exhaust energy recovery device comprising: a step of generating electric power by driving a power turbine with the extracted exhaust gas,
Adjusting the flow rate of the extracted exhaust gas flowing into the power turbine by a gas inlet control valve that throttles the flow rate of the extracted exhaust gas; and installing the extracted gas upstream of the gas inlet control valve. A bypass pipe that bypasses a part of the exhaust gas to the downstream side of the power turbine, and a step of adjusting a flow rate of the exhaust gas that bypasses the power turbine by an exhaust gas bypass control valve installed in the bypass pipe. In the engine exhaust energy recovery method,
Detecting engine load, engine speed , engine scavenging pressure , and engine cylinder pressure;
Calculating a cylinder compression pressure from the detected cylinder pressure of the engine;
Calculating an optimum in-cylinder compression pressure at which the fuel consumption rate of the engine is the smallest from the detected engine load and engine speed;
Calculating a change amount of the exhaust valve closing timing based on the difference after calculating the difference between the calculated in-cylinder compression pressure and the calculated in-cylinder optimum compression pressure;
Determining the exhaust valve closing timing from the calculated exhaust valve closing timing change amount;
Changing the exhaust valve closing timing based on the determined exhaust valve closing timing,
A step of detecting the in-cylinder compression pressure of the engine after changing the exhaust valve closing timing;
Calculating an error between the in-cylinder compression pressure of the engine after changing the detected exhaust valve closing timing and the optimum compression pressure in the cylinder;
Feeding back the calculated error to the exhaust valve closing timing command value;
An engine exhaust energy recovery method comprising: A step of driving the engine, a step of driving the exhaust turbine supercharger by the exhaust gas discharged from the engine, and pumping outside air to the engine body, and a part of the exhaust gas discharged from the engine is extracted. An operation method of an engine exhaust energy recovery device comprising: a step of generating electric power by driving a power turbine with the extracted exhaust gas,
Adjusting the flow rate of the extracted exhaust gas flowing into the power turbine by a gas inlet control valve that throttles the flow rate of the extracted exhaust gas; and installing the extracted gas upstream of the gas inlet control valve. A bypass pipe that bypasses a part of the exhaust gas to the downstream side of the power turbine, and a step of adjusting a flow rate of the exhaust gas that bypasses the power turbine by an exhaust gas bypass control valve installed in the bypass pipe. In the engine exhaust energy recovery method,
Detecting engine load, engine speed , engine scavenging pressure , and engine cylinder pressure;
Calculating a maximum cylinder pressure from the detected cylinder pressure of the engine;
Calculating an optimum maximum pressure in the cylinder that minimizes the fuel consumption rate of the engine from the detected engine load and engine speed;
Calculating a change amount of the fuel injection timing based on the difference between the calculated maximum pressure in the cylinder and the calculated optimal maximum pressure in the cylinder; and
Determining the fuel injection timing from the calculated change amount of the fuel injection timing;
Changing the fuel injection timing based on the determined fuel injection timing,
A step of detecting the maximum pressure in the cylinder of the engine after changing the fuel injection timing;
Calculating an error between the maximum in-cylinder pressure of the engine after changing the detected fuel injection timing and the optimal maximum pressure in the cylinder;
Feeding back the calculated error to the fuel injection timing command value;
An engine exhaust energy recovery method comprising: A step of driving the engine, a step of driving the exhaust turbine supercharger by the exhaust gas discharged from the engine, and pumping outside air to the engine body, and a part of the exhaust gas discharged from the engine is extracted. An operation method of an engine exhaust energy recovery device comprising: a step of generating electric power by driving a power turbine with the extracted exhaust gas,
Adjusting the flow rate of the extracted exhaust gas flowing into the power turbine by a gas inlet control valve that throttles the flow rate of the extracted exhaust gas; and installing the extracted gas upstream of the gas inlet control valve. A bypass pipe that bypasses a part of the exhaust gas to the downstream side of the power turbine, and a step of adjusting a flow rate of the exhaust gas that bypasses the power turbine by an exhaust gas bypass control valve installed in the bypass pipe. In the engine exhaust energy recovery method,
Detecting engine load, engine speed, engine scavenging pressure, and engine cylinder pressure;
Calculating a cylinder compression pressure and a cylinder maximum pressure from the detected cylinder pressure of the engine;
Calculating the optimum compression pressure in the cylinder that minimizes the fuel consumption rate of the engine and the optimum maximum pressure in the cylinder from the detected engine load and engine speed;
Calculating the opening correction amount of the exhaust gas bypass control valve based on the difference after obtaining the difference between the calculated in-cylinder compression pressure and the optimum compression pressure in the cylinder;
Determining an opening command value of the exhaust gas bypass control valve from the calculated opening correction amount of the exhaust gas bypass control valve;
Changing the opening degree of the exhaust gas bypass control valve based on the determined opening degree command value of the exhaust gas bypass control valve, and
A step of detecting the in-cylinder compression pressure of the engine after changing the opening of the exhaust gas bypass control valve;
Calculating an error between the in-cylinder compression pressure of the engine after changing the detected opening degree of the exhaust gas bypass control valve and the optimum compression pressure in the cylinder;
Determining whether or not the changed opening of the exhaust gas bypass valve is fully closed, and determining the engine exhaust valve closing timing based on the calculated error in the case of full closing;
Determining fuel injection timing of the engine based on a difference between the maximum pressure in the cylinder and the optimal maximum pressure in the cylinder;
Changing the engine exhaust valve closing timing and the determined engine fuel injection timing based on the determined engine exhaust valve closing timing and the determined engine fuel injection timing; and
An engine exhaust energy recovery method comprising: Detecting the compression pressure in the cylinder after changing the exhaust valve closing timing of the engine and the fuel injection timing of the engine, and the maximum pressure in the cylinder;
If there is an error between the calculated optimum maximum pressure in the cylinder, the exhaust valve closing timing of the engine, and the maximum pressure in the cylinder after changing the fuel injection timing of the engine, the fuel valve injection is performed based on the error. Determining a timing correction amount and determining a fuel injection timing by feeding back the fuel valve injection timing correction amount; and
If there is an error between the calculated optimum compression pressure in the cylinder and the exhaust valve closing timing of the engine and the compression pressure in the cylinder after changing the fuel injection timing of the engine, the exhaust valve closing timing is based on the error. Determining a correction amount and determining the exhaust valve closing timing by feeding back the exhaust valve closing timing correction amount; and
The engine exhaust energy recovery method according to claim 3, further comprising :

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