JP7456351B2 - Engine system and control method - Google Patents

Description

This disclosure relates to an engine system and a control method, and particularly to an engine system including a supercharger including a variable nozzle mechanism.

Conventionally, there has been an engine system that includes a compression pressure release type engine brake device and a turbocharger (for example, see Patent Document 1). A compression pressure release type engine brake device operates as an engine brake by opening and closing an exhaust valve at a timing different from the normal exhaust timing to control the pressure state within the cylinder of the engine. The turbocharger includes a variable nozzle for throttling the exhaust gas to the exhaust turbine side. In addition to the engine braking system, when the accelerator pedal is no longer pressed, the engine braking force can be increased by controlling the opening of the variable nozzle to its narrowest state, thereby increasing the exhaust pressure.

Furthermore, when the opening degree of the variable nozzle is at its narrowest, if the supercharging pressure by the turbocharger becomes greater than a predetermined pressure, the variable nozzle is changed in the opening direction by one step. Thereby, it is possible to prevent the supercharging pressure from increasing too much and applying an excessive load to the engine and the turbocharger.

Japanese Patent Application Laid-Open No. 10-18866

However, Patent Document 1 does not take into account the state of the exhaust gas, so if the exhaust pressure rises too much, it may adversely affect equipment in the exhaust path, or conversely, if the exhaust pressure drops too much, it may cause damage to the specified engine. A problem may arise that braking force may not be obtained.

This disclosure has been made to solve the above-mentioned problems, and its purpose is to provide an engine system and a control method that can prevent exhaust pressure from increasing too much.

The engine system according to this disclosure includes a turbine driven by exhaust gas discharged from the engine and a variable nozzle mechanism that adjusts the flow velocity of the exhaust gas flowing into the turbine by the opening degree of the nozzle, and supercharges intake air to the engine. and a control device that controls the variable nozzle mechanism. In response to a deceleration request from the user, the control device calculates a correction amount for the nozzle opening according to the temperature of exhaust gas from the engine, and adjusts the nozzle opening so that the opening is the same as the reference opening minus the correction amount. control.

Preferably, the control device corrects the opening degree so that the pressure of exhaust gas from the engine does not exceed a predetermined pressure. More preferably, a first control range of the opening degree of the nozzle is specified in advance in which the pressure of the exhaust gas from the engine does not exceed a predetermined pressure with respect to the temperature of the exhaust gas from the engine, and the control device controls the first control range. Correct the opening within the range.

Preferably, the control device corrects the opening degree so that the deceleration force by the engine exceeds a predetermined target. More preferably, a second control range of the nozzle opening in which the deceleration force by the engine exceeds a predetermined target with respect to the temperature of the exhaust gas from the engine is specified in advance, and the control device is configured to control the nozzle opening in the second control range. Correct the degree.

According to another aspect of this disclosure, an engine system control method includes a turbine driven by exhaust gas discharged from the engine, and a variable nozzle mechanism that adjusts the flow rate of the exhaust gas flowing into the turbine by the opening degree of the nozzle. This is a control method for controlling a variable nozzle mechanism of a supercharger that supercharges intake air to an engine. The control method consists of two steps: in response to a deceleration request from the user, a correction amount for the nozzle opening is calculated according to the temperature of the exhaust gas from the engine, and the opening is calculated by subtracting the correction amount from the standard opening. , controlling the nozzle.

This disclosure provides an engine system and control method that can prevent exhaust pressure from rising too high.

FIG. 1 is a diagram showing a schematic configuration of an engine including a supercharger according to the present embodiment. It is a figure showing an example of composition of a variable nozzle mechanism. 4 is a flowchart showing the flow of a VN control process in this embodiment. It is a graph showing the relationship among engine rotation speed, atmospheric pressure, outside temperature, and reference VN opening degree. It is a graph showing the relationship between the correction amount of the VN opening degree and the exhaust temperature. It is a graph showing an example of the result of control according to this embodiment.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the same parts are given the same symbols. Their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated.

FIG. 1 is a diagram showing a schematic configuration of an engine 1 including a supercharger according to the present embodiment. In the present embodiment, the engine 1 will be described using a common rail diesel engine as an example, but it may be another type of engine (eg, a gasoline engine, etc.).

The engine 1 includes an engine body 10, an air cleaner 20, an intercooler 26, an intake manifold 28, a supercharger 30, an exhaust manifold 50, an exhaust treatment device 55, and an exhaust gas recirculation device (hereinafter referred to as EGR). 60, an engine speed sensor 102, an air flow meter 104, a boost pressure sensor 106, an outside temperature sensor 108, an atmospheric pressure sensor 110, and a control device 200.

Engine body 10 includes a cylinder 12 and an injector 16. The engine 1 may be an in-line engine or an engine with other cylinder layouts (eg, V-type or horizontal type).

The injector 16 is a fuel injection device provided at the top of the cylinder 12 and connected to a common rail (not shown). Fuel stored in a fuel tank (not shown) is pressurized to a predetermined pressure by a supply pump (not shown) and then supplied to the common rail. The fuel supplied to the common rail is injected from the injector 16 at a predetermined timing. The injector 16 supplies a fuel injection amount Qv instructed according to a control signal from the control device 200 into the cylinder 12 .

The air cleaner 20 removes foreign matter from the air taken in from the outside of the engine 1. One end of a first intake pipe 22 is connected to the air cleaner 20 .

The other end of the first intake pipe 22 is connected to an intake inlet of a compressor 32 of a supercharger 30 . One end of the second intake pipe 24 is connected to an intake outlet of the compressor 32 . The compressor 32 supercharges the air flowing from the first intake pipe 22 and supplies it to the second intake pipe 24 . The detailed operation of the compressor 32 will be described later.

One end of an intercooler 26 is connected to the other end of the second intake pipe 24 . The intercooler 26 is an air-cooled or water-cooled heat exchanger that cools the air flowing through the second intake pipe 24.

One end of a third intake pipe 27 is connected to the other end of the intercooler 26 . An intake manifold 28 is connected to the other end of the third intake pipe 27. The intake manifold 28 is connected to the intake port of the cylinder 12 of the engine body 10. A diesel throttle 25 is provided in the middle of the third intake pipe 27 and closer to the intercooler 26 than the branch point with the EGR 60, which will be described later. The diesel throttle 25 adjusts the flow rate of intake air according to a control signal from the control device 200.

The exhaust manifold 50 is connected to the exhaust port of the cylinder 12 of the engine body 10. One end of a first exhaust pipe 52 is connected to the exhaust manifold 50 . The other end of the first exhaust pipe 52 is connected to an exhaust inlet of the turbine 36 of the supercharger 30. Therefore, the exhaust gas discharged from the exhaust port of each cylinder is supplied to the turbine 36 via the exhaust manifold 50 and the first exhaust pipe 52.

One end of a second exhaust pipe 54 is connected to the exhaust outlet of the turbine 36 . The other end of the second exhaust pipe 54 is connected to an exhaust treatment device 55 including an oxidation catalyst 56, a PM (Particulate Matter) removal filter 57, and an SCR catalyst 58, a muffler, and the like. Therefore, the exhaust gas discharged from the exhaust outlet of the turbine 36 is discharged to the outside of the vehicle via the second exhaust pipe 54, the exhaust treatment device 55, the muffler, and the like.

The third intake pipe 27 (or intake manifold 28) and the first exhaust pipe 52 (or exhaust manifold 50) are connected by the EGR device 60 without going through the cylinder 12 of the engine body 10. EGR device 60 includes an EGR valve 62, an EGR passage 66, and an EGR cooler 63. The EGR passage 66 connects the third intake pipe 27 and the first exhaust pipe 52 (or exhaust manifold 50). The EGR valve 62 and the EGR cooler 63 are provided in the middle of the EGR passage 66. The EGR cooler 63 is an air-cooled or water-cooled heat exchanger that cools EGR gas flowing to the intake side via the EGR passage 66.

The EGR valve 62 is a regulating valve that adjusts the flow rate of EGR gas flowing through the EGR passage 66 in accordance with a control signal from the control device 200. The exhaust gas in the exhaust manifold 50 is returned to the intake side as EGR gas via the EGR device 60, thereby lowering the combustion temperature in the cylinder 12 and reducing the amount of NOx produced.

Supercharger 30 includes a compressor 32, a turbine 36, a variable nozzle mechanism 40, and an actuator 44. A compressor wheel 34 is housed within the housing of the compressor 32, and a turbine wheel 38 is housed within the housing of the turbine 36. The compressor wheel 34 and the turbine wheel 38 are connected by a connecting shaft 42 and rotate together. Therefore, the compressor wheel 34 is rotationally driven by the energy of the exhaust gas supplied to the turbine wheel 38.

The variable nozzle mechanism 40 includes a plurality of vanes (see FIG. 2) that are arranged at an exhaust inflow section around the rotation axis of the turbine wheel 38 and guide exhaust gas supplied from the first exhaust pipe 52 to the turbine wheel 38. , a link mechanism that changes the gap between adjacent vanes (in the following description, the size of this gap is also referred to as "VN (vane nozzle) opening degree") by rotating each of the plurality of vanes. The actuator 44 changes the VN opening degree of the variable nozzle mechanism 40 by operating the link mechanism in response to an operation instruction from the control device 200.

By changing the VN opening degree of the variable nozzle mechanism 40, the exhaust flow path at the exhaust gas inflow portion to the turbine wheel 38 is narrowed or expanded. Thereby, the flow velocity of the exhaust gas blown onto the turbine wheel 38 can be changed.

FIG. 2 is a diagram showing an example of the configuration of the variable nozzle mechanism 40. FIG. 2(a) is a diagram of the variable nozzle mechanism 40 viewed from the left in FIG. FIG. 2(b) is a diagram of the variable nozzle mechanism 40 seen from the right side in FIG. The variable nozzle mechanism 40 may have any configuration as long as it changes the flow rate of the exhaust gas supplied to the turbine wheel 38 by narrowing the exhaust flow path from the first exhaust pipe 52 to the turbine wheel 38. In particular, the configuration shown in FIG. It is not limited to the configuration shown in .

As shown in FIGS. 2(a) and 2(b), the variable nozzle mechanism 40 includes a plurality of nozzle vanes 67 disposed at the exhaust inlet on the outer periphery of the turbine wheel 38, and a plurality of nozzle vanes 67 arranged around a plurality of shafts 68 as rotation centers. and a unison ring 71 that rotates the shaft 68 using an arm 70 fixed to the end of each shaft 68. The unison ring 71 is rotated by the operation of the actuator 44 via the link mechanism 72, and the arm 72b fixed to the end of the rotating shaft 72a of the link mechanism 72 is swung using the actuator 44. By doing so, the unison ring 71 that engages with the arm 72b can be rotated.

For example, as shown in FIG. 2(a), when the arm 72b is swung in the direction shown by the arrow by the link mechanism 72, the unison ring 71 is moved in the direction shown by the arrow, that is, counterclockwise in FIG. 2(a). In FIG. 2(b), it rotates clockwise. Further, due to the rotation of the unison ring 71, each shaft 68 is rotated in the direction shown by the arrow, that is, counterclockwise in FIG. 2(a) and clockwise in FIG. 2(b). Therefore, the opening degree of the nozzle vane 67 is controlled to the closed side (so that the gap between two adjacent nozzle vanes becomes narrower). Furthermore, when the arm 72b is swung in the direction opposite to the arrow, the opening degree of the nozzle vane 67 is controlled to the opening side (so that the gap between two adjacent nozzle vanes widens).

Returning to FIG. 1, the operation of engine 1 is controlled by control device 200. The control device 200 includes a CPU (Central Processing Unit) that performs various processes, a ROM (Read Only Memory) that stores programs and data, and a RAM (Random Access Memory) that stores CPU processing results and the like. It includes input/output ports (none of which are shown) for exchanging information with the outside. The input ports are connected to the sensors described above (for example, engine rotational speed sensor 102, air flow meter 104, boost pressure sensor 106, outside temperature sensor 108, and atmospheric pressure sensor 110). Devices to be controlled (eg, injector 16, actuator 44, EGR valve 62, etc.) are connected to the output port.

Control device 200 controls various devices so that engine 1 is in a desired operating state based on signals from each sensor and device, as well as maps and programs stored in memory. Note that various controls are not limited to processing by software, but can also be processed by dedicated hardware (electronic circuits). The control device 200 also includes a built-in timer circuit (not shown) for measuring time.

The engine speed sensor 102 detects the rotation speed of the crankshaft, which is the output shaft of the engine 1, as the engine speed NE. The engine speed sensor 102 transmits a signal indicating the detected engine speed NE to the control device 200.

The air flow meter 104 detects the flow rate (intake air amount) Qin of fresh air introduced into the first intake pipe 22. Air flow meter 104 transmits a signal indicating the detected intake air amount Qin to control device 200.

The boost pressure sensor 106 detects the pressure in the intake manifold 28 as the boost pressure. The boost pressure sensor 106 transmits a signal indicating the detected boost pressure to the control device 200.

The outside temperature sensor 108 detects the temperature of the outside air of the vehicle in which the engine 1 is mounted. The outside temperature sensor 108 transmits a signal indicating the detected outside air temperature to the control device 200.

Atmospheric pressure sensor 110 detects the pressure of the outside air of the vehicle in which engine 1 is mounted, that is, atmospheric pressure. Atmospheric pressure sensor 110 transmits a signal indicating the detected atmospheric pressure to control device 200.

In the engine 1 having the above configuration, the control device 200 controls the variable nozzle mechanism 40 based on the state of the engine 1. More specifically, control device 200 sets the basic value of the VN opening degree of variable nozzle mechanism 40 based on the state of engine 1 (for example, engine rotational speed NE and fuel injection amount Qv).

For example, when the engine rotation speed NE is in a low rotation range and the load is in a low load range, the control device 200 controls the flow rate of the exhaust gas supplied to the turbine wheel 38 to be high (i.e., Set the basic value so that the VN opening degree becomes small.

On the other hand, the control device 200 controls the flow rate of the exhaust gas supplied to the turbine wheel 38 to be slow ( In other words, the basic value is set so that the VN opening degree becomes large.

Further, the control device 200 calculates a correction amount for the VN opening degree using the difference between the target boost pressure and the actual boost pressure. The control device 200 sets the target boost pressure using, for example, the engine rotational speed NE, the intake air amount Qin, the fuel injection amount Qv, and the like. Control device 200 uses boost pressure sensor 106 to obtain actual boost pressure.

The control device 200 generates a control signal for controlling the actuator 44 by using a value obtained by correcting the set basic value by the correction amount as a command value for the VN opening degree, and transmits the control signal to the actuator 44 . The actuator 44 of the variable nozzle mechanism 40 changes the VN opening degree based on the received control signal. In this way, by appropriately adjusting the VN opening degree of the variable nozzle mechanism 40 based on the state of the engine 1, the supercharging pressure of the supercharger 30 can be adjusted to the optimal supercharging pressure.

In the supercharger 30 having such a variable nozzle mechanism 40, the VN opening degree of the variable nozzle mechanism 40 is controlled so that the pressure in the exhaust manifold 50 does not exceed the upper pressure limit for engine protection. In other words, the lower limit value of the VN opening is set to the value obtained by correcting the above-mentioned basic value with the correction amount, and if the value obtained by correcting the basic value with the correction amount is smaller than the lower limit value, the lower limit value is set to the value obtained by correcting the basic value with the correction amount. The actuator 44 of the variable nozzle mechanism 40 is controlled as the command value. The lower limit value of the VN opening degree is set, for example, using the engine rotational speed NE and the fuel injection amount Qv on the premise that the exhaust flow rate is in a stable state with little fluctuation.

[assignment]
Conventionally, in such an engine 1 system, when the driver performs an operation to decelerate the vehicle (for example, an operation in which the accelerator pedal is not depressed at all or an operation in which the brake pedal is depressed), the variable nozzle mechanism 40 is activated. Some have increased the engine braking force by increasing the exhaust pressure by controlling the VN opening to the narrowest possible state.

However, in this engine 1 system, the condition of the exhaust gas is not taken into consideration, so the exhaust pressure may rise too much and have a negative impact on the equipment in the exhaust path, or conversely, the exhaust pressure may drop too much. A problem may arise in that a predetermined engine braking force may not be obtained.

[Controls in this disclosure]
Therefore, in this disclosure, the control device 200 calculates a correction amount for the VN opening degree of the variable nozzle mechanism 40 according to the temperature of exhaust gas from the engine in response to a deceleration request from the user, and calculates a correction amount for the VN opening degree according to the temperature of the exhaust gas from the engine. The variable nozzle mechanism 40 is controlled so that the opening degree is obtained by subtracting the correction amount from the opening degree. This makes it possible to prevent the exhaust pressure from increasing too much.

The control in this embodiment will be described below. Figure 3 is a flowchart showing the flow of the VN control process in this embodiment. This VN control process is called from a higher-level process and executed by the CPU of the control device 200 at a predetermined control cycle.

Referring to FIG. 3, first, the CPU of the control device 200 calculates the reference VN opening (step S111). The reference VN opening is, for example, the aforementioned value obtained by correcting the basic value of the VN opening by the correction amount.

FIG. 4 is a graph showing the relationship among engine speed, atmospheric pressure, outside temperature, and reference VN opening degree. Referring to FIG. 4, for example, when the atmospheric pressure and outside temperature are determined, one line in the graph of FIG. 4 is determined, and the reference VN opening degree corresponding to the engine rotational speed NE can be specified on that line. can. Here, the reference VN opening degree decreases as the engine rotation speed increases.

Returning to FIG. 3, the CPU of the control device 200 determines whether the accelerator pedal is turned off, that is, whether the accelerator pedal is not operated (step S112).

If it is determined that the accelerator pedal is not operated (YES in step S112), the CPU of the control device 200 specifies the temperature T4 of the exhaust gas (step S113). The exhaust temperature T4 is obtained, for example, by adding the temperature rise in the cylinder 12 (the value obtained by dividing the exhaust loss (J) by the specific heat x the gas amount (g)) to the temperature of the intake air in the intake manifold 28. For example, the exhaust temperature T4 is determined based on the engine speed NE, the intake air temperature in the intake manifold 28, the water temperature, combustion parameters such as the fuel injection amount Qv and injection timing, the intake air amount Qin, and the cylinder 12 per cycle. It is estimated by a known method using the amount of gas passing through the air. The intake air temperature and water temperature are detected using, for example, a sensor (not shown). Note that the exhaust gas temperature T4 may be specified using a temperature sensor. Further, the temperature of a member of the supercharger 30 (for example, the turbine 36) may be used instead of the exhaust temperature T4.

Next, the CPU of the control device 200 calculates a correction amount for the VN opening degree (step S114). The VN opening degree correction amount is calculated using, for example, the exhaust gas temperature T4.

FIG. 5 is a graph showing the relationship between the VN opening degree correction amount and exhaust temperature. Referring to FIG. 5, the correction amount of the VN opening degree corresponding to the exhaust gas temperature T4 can be specified on the line of this graph. In this embodiment, the correction amount is 0 when the exhaust gas temperature T4 is below a predetermined value, and decreases as the exhaust gas temperature increases when the exhaust gas temperature T4 exceeds the predetermined value. In other words, the correction amount is a value of 0 or less.

Returning to FIG. 3, the CPU of the control device 200 calculates the corrected VN opening degree (step S115). The corrected VN opening degree is calculated by adding the correction amount (0 or less) calculated in step S114 to the reference VN opening degree specified in step S111.

If it is determined that the accelerator pedal is not in an unoperated state (NO in step S112), or after step S115, the CPU of the control device 200 controls the variable nozzle mechanism 40 to achieve the calculated VN opening (step S116). After step S116, the CPU of the control device 200 returns the process to be executed to the higher-level process that called this VN control process.

FIG. 6 is a graph showing an example of the result of control according to this embodiment. Referring to FIG. 6, as shown in FIG. 6(A), when the opening degree of the accelerator pedal is set to 0 at time t1, fuel is no longer injected into the cylinder 12, so as shown in FIG. 6(B). As shown, the exhaust temperature T4 monotonically decreases.

As shown in FIG. 6(C), until time t1, the VN opening is set according to the accelerator opening and the like. After time t1, the variable nozzle mechanism 40 is controlled so that the VN opening degree is the reference VN opening degree plus the VN opening correction amount.

As a result, as shown in FIG. 6(D), the pressure inside the exhaust manifold 50 is prevented from exceeding the reliability limit, and as shown in FIG. 6(E), the pressure inside the exhaust manifold 50 is prevented from exceeding the reliability limit. The deceleration force of the engine brake by the variable nozzle mechanism 40 is made to exceed a predetermined target (for example, the minimum necessary deceleration force).

In this embodiment, when the engine brake is applied by the variable nozzle mechanism 40 by controlling the VN opening degree, the VN opening is such that the pressure in the exhaust manifold 28 does not exceed the reliability limit under various conditions such as exhaust temperature. The VN opening correction amount shown in FIG. A graph is determined in advance.

Further, when the engine brake by the variable nozzle mechanism 40 is applied by controlling the VN opening degree, the deceleration force of the engine brake by the variable nozzle mechanism 40 exceeds a predetermined target for various conditions such as exhaust temperature. The control range is specified in advance, and the VN opening correction amount graph shown in FIG. is determined in advance.

[Modified example]
(1) In the embodiment described above, the system configuration of the engine 1 is as shown in FIGS. 1 and 2. However, the present invention is not limited to this, and an engine system having a configuration different from that shown in FIGS. 1 and 2 may be used as long as the engine system includes a supercharger including a variable nozzle mechanism.

(2) In the embodiment described above, as shown in step S112 in FIG. 3, the VN opening degree corrected according to the exhaust temperature is calculated on the condition that the accelerator pedal is not operated. I made it. However, the condition for calculating the corrected VN opening is not limited to this, and may be any condition that there is some kind of deceleration request from the driver. For example, if the engine brake based on the VN opening is turned on or off, The condition may also be that the operating section to turn on is switched to the on-state side.

(3) In the embodiment described above, the reference VN opening degree is calculated based on the relationship shown in the graph shown in FIG. However, the present invention is not limited thereto, and the reference VN opening degree may be calculated using any other known method.

(4) In the above-described embodiment, the graph in FIG. 5 specifies in advance a range of VN opening within which the pressure in the exhaust manifold 28 does not exceed the reliability limit for each condition, such as exhaust temperature, when engine braking is performed by the variable nozzle mechanism 40 through control of the VN opening, and the VN opening correction amount is determined in advance within this range of VN opening for each condition, such as exhaust temperature. The VN opening is then corrected using the graph in FIG. 5. However, this is not limited to this, and other methods may be used as long as the VN opening is corrected so that the exhaust pressure from the engine 1 does not exceed a predetermined pressure.

(5) In the embodiment described above, the graph in FIG. 5 shows the effect of the variable nozzle mechanism 40 on various conditions such as exhaust temperature when the engine brake is applied by the variable nozzle mechanism 40 by controlling the VN opening degree. The VN opening range in which the deceleration force of the engine brake exceeds a predetermined target is specified in advance, and the VN opening correction amount is determined within this VN opening range for each condition such as exhaust temperature. can be determined in advance. Then, the VN opening degree was corrected using the graph of FIG. 5. However, the method is not limited to this, and other methods may be used as long as the VN opening degree is corrected so that the deceleration force by the engine 1 exceeds a predetermined target.

(6) In the embodiment described above, as shown in FIG. 6, the VN The opening degree has been corrected. However, the VN is not limited to this, and the VN is opened so that at least one of the following conditions is satisfied: the pressure of exhaust gas from the engine 1 does not exceed a predetermined pressure, and the condition that the deceleration force from the engine 1 exceeds a predetermined target. The degree may be corrected.

(7) The above disclosure can be considered as a disclosure of the system of the engine 1, as a disclosure of the control device 200 of the engine 1, and as a disclosure of a vehicle equipped with the engine 1. This can be considered as disclosure of a control method or a control program executed by the control device 200.

[summary]
(1) As shown in FIGS. 1 and 2, the engine 1 system adjusts the turbine 36 driven by the exhaust gas discharged from the engine 1 and the flow rate of the exhaust gas flowing into the turbine 36 by the VN opening degree. A supercharger 30 that includes a variable nozzle mechanism 40 and supercharges intake air to the engine 1 , and a control device 200 that controls the variable nozzle mechanism 40 . As shown in FIGS. 3 to 5, the control device 200 controls the VN opening according to the temperature of the exhaust gas in order to prevent the pressure of the exhaust gas from the engine 1 from rising too much in response to a deceleration request from the user. (steps S112 to S114), and controls the variable nozzle mechanism 40 so that the VN opening is the same as the reference VN opening (step S115).

As a result, the variable nozzle mechanism is controlled so that the VN opening degree is corrected from the reference VN opening degree. As a result, it is possible to prevent the exhaust pressure from increasing too much.

(2) As shown in FIGS. 3 to 6, the control device 200 corrects the VN opening degree so that the pressure of exhaust gas from the engine 1 does not exceed a predetermined pressure. This makes it possible to prevent the exhaust pressure from increasing too much.

(3) As shown in FIG. 6, a control range of the VN opening degree is specified in advance so that the pressure of the exhaust gas from the engine does not exceed a predetermined pressure with respect to the temperature of the exhaust gas from the engine. As shown in FIGS. 3 to 6, the control device 200 corrects the VN opening degree within its control range. This makes it possible to prevent the exhaust pressure from increasing too much.

(4) As shown in Figures 3 to 6, the control device 200 corrects the VN opening so that the deceleration force of the engine 1 exceeds a predetermined target. This makes it possible to obtain a deceleration force that exceeds the predetermined target.

(5) As shown in FIG. 6, a control range of the VN opening degree in which the deceleration force of the engine 1 exceeds a predetermined target with respect to the temperature of the exhaust gas from the engine 1 is specified in advance. As shown in FIGS. 3 to 6, the control device 200 corrects the VN opening degree within its control range. Thereby, a deceleration force exceeding a predetermined target can be obtained.

It is also planned that the embodiments disclosed herein will be implemented in appropriate combinations. The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is indicated by the claims rather than the description of the embodiments described above, and it is intended that all changes within the meaning and scope equivalent to the claims are included.

1 engine, 10 engine body, 12 cylinder, 16 injector, 20 air cleaner, 22 first intake pipe, 24 second intake pipe, 25 diesel throttle, 26 intercooler, 27 third intake pipe, 28 intake manifold, 30 supercharger , 32 compressor, 34 compressor wheel, 36 turbine, 38 turbine wheel, 40 variable nozzle mechanism, 42 connecting shaft, 44 actuator, 50 exhaust manifold, 52 first exhaust pipe, 54 second exhaust pipe, 55 exhaust treatment device, 56 oxidation Catalyst, 57 PM removal filter, 58 SCR catalyst, 60 EGR device, 62 EGR valve, 63 EGR cooler, 66 EGR passage, 67 nozzle vane, 68 shaft, 69 nozzle plate, 70, 72b arm, 71 unison ring, 72 link mechanism, 72a rotation shaft, 102 engine rotation speed sensor, 104 air flow meter, 106 boost pressure sensor, 108 outside temperature sensor, 110 atmospheric pressure sensor, 200 control device.

Claims (6)

A supercharger that supercharges intake air to the engine, including a turbine driven by exhaust gas discharged from the engine, and a variable nozzle mechanism that adjusts the flow rate of the exhaust gas flowing into the turbine by the opening degree of the nozzle;
and a control device that controls the variable nozzle mechanism,
The control device includes:
In response to a deceleration request from a user, calculate a correction amount for the opening degree of the nozzle according to the temperature of exhaust gas from the engine,
An engine system that controls the nozzle only during deceleration so that the opening is corrected by the correction amount from the reference opening. The engine system according to claim 1, wherein the control device corrects the opening degree so that the pressure of exhaust gas from the engine does not exceed a predetermined pressure. The engine system according to claim 1, wherein the control device corrects the opening degree so that the deceleration force by the engine exceeds a predetermined target. A supercharger that supercharges intake air to the engine, including a turbine driven by exhaust gas discharged from the engine, and a variable nozzle mechanism that adjusts the flow rate of the exhaust gas flowing into the turbine by the opening degree of the nozzle;
and a control device that controls the variable nozzle mechanism,
The control device includes:
In response to a deceleration request from a user, calculate a correction amount for the opening degree of the nozzle according to the temperature of exhaust gas from the engine,
controlling the nozzle so that the opening is corrected by the correction amount from the reference opening;
correcting the opening degree so that the pressure of exhaust gas from the engine does not exceed a predetermined pressure;
specifying in advance a first control range of the opening degree of the nozzle in which the pressure of the exhaust gas from the engine does not exceed the predetermined pressure with respect to the temperature of the exhaust gas from the engine;
The control device is an engine system, wherein the control device corrects the opening degree within the first control range. A supercharger that supercharges intake air to the engine, including a turbine driven by exhaust gas discharged from the engine, and a variable nozzle mechanism that adjusts the flow rate of the exhaust gas flowing into the turbine by the opening degree of the nozzle;
and a control device that controls the variable nozzle mechanism,
The control device includes:
In response to a deceleration request from a user, calculate a correction amount for the opening degree of the nozzle according to the temperature of exhaust gas from the engine,
controlling the nozzle so that the opening is corrected by the correction amount from the reference opening;
correcting the opening degree so that the deceleration force by the engine exceeds a predetermined target;
specifying in advance a second control range of the opening degree of the nozzle in which the deceleration force by the engine exceeds a predetermined target with respect to the temperature of the exhaust gas from the engine;
The control device is an engine system in which the control device corrects the opening degree within the second control range. The supercharger includes a turbine driven by exhaust gas discharged from the engine, and a variable nozzle mechanism that adjusts the flow rate of the exhaust gas flowing into the turbine by the opening degree of the nozzle, and supercharges intake air to the engine. A control method for controlling a variable nozzle mechanism, comprising:
calculating a correction amount for the opening degree of the nozzle according to the temperature of exhaust gas from the engine in response to a deceleration request from a user;
A control method comprising the step of controlling the nozzle only during deceleration so that the opening is corrected by the correction amount from the reference opening.

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