JP7439736B2 - Engine system, control device, and engine control method - Google Patents

Description

The present invention relates to an engine system, a control device, and an engine control method.

Japanese Unexamined Patent Publication No. 2002-47942 (Patent Document 1) discloses a control system for an internal combustion engine having a supercharger. A supercharger includes a turbine that is operated by exhaust gas discharged from the internal combustion engine, a compressor that supercharges the air taken into the internal combustion engine by the operation of the turbine, and a vane that changes the flow rate of the exhaust gas that operates the turbine. A variable nozzle mechanism is provided. The control system is configured to control the variable nozzle mechanism so that the intake pressure (supercharging pressure) after being supercharged by the supercharger does not exceed a predetermined upper limit supercharging pressure (constant value). . Further, the variable nozzle mechanism narrows the exhaust flow path by reducing the opening degree of the vane, thereby increasing the flow velocity of the exhaust gas supplied to the turbine wheel. Further, the variable nozzle mechanism widens the exhaust flow path and reduces the flow velocity by increasing the opening degree of the vane.

Japanese Patent Application Publication No. 2002-47942

However, in Patent Document 1, the supercharging pressure may increase excessively due to some abnormality occurring in the engine system. To explain an example of a case where the supercharging pressure increases excessively, for example, the vane may become stuck due to unburned fuel adhering to the vane while the opening degree of the vane is small. In this case, when the driver of the vehicle depresses the accelerator pedal, the amount of injection from the vehicle increases. Along with this, the temperature of the exhaust manifold gas, the pressure of the exhaust manifold gas, the rotational speed of the turbine wheel, etc. increase, and the boost pressure also increases. Here, in the engine system, it is necessary to increase the opening degree of the vanes in order to prevent excessive increases in exhaust manifold gas temperature, exhaust manifold gas pressure, turbine wheel rotation speed, and boost pressure. However, since the vanes are fixed, the degree of opening of the vanes cannot be increased, and as a result, a problem may occur in which the supercharging pressure increases excessively. If the boost pressure increases excessively, problems with the engine system will occur.

The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a technique for suppressing an excessive increase in supercharging pressure.

An engine system according to an aspect of the present disclosure includes an engine, a supercharger that supercharges the engine, and a control device that sets an upper limit injection amount for the engine. The control device acquires the actual boost pressure of the turbocharger, acquires the reference maximum boost pressure of the turbocharger, and sets the boost pressure to the smaller of the actual boost pressure and the reference maximum boost pressure. Set the upper limit injection amount accordingly.

In this way, it is possible to prevent the supercharging pressure from increasing excessively.
In one aspect, the control device acquires environmental information indicating the environment of the engine system, and acquires a reference maximum boost pressure based on the environmental information.

In this way, the control device can obtain the reference maximum boost pressure in consideration of the environmental information of the engine system.

In some aspects, the environmental information includes temperature around the engine system or air pressure around the engine system.

In this way, the control device can obtain the reference maximum boost pressure in consideration of the temperature around the engine system or the atmospheric pressure around the engine system.

In one aspect, the control device obtains a reference maximum boost pressure based on the engine speed.

In this way, the control device can obtain the reference maximum boost pressure in consideration of the engine speed.

In one aspect, the control device sets an upper limit injection amount according to the smaller boost pressure when the smaller boost pressure is less than a threshold, and when the smaller boost pressure is greater than the threshold. A fixed upper limit injection amount is set for .

In this way, it is possible to prevent the control device from setting an excessively large upper limit injection amount.

In certain aspects, the threshold value varies depending on the environment of the engine system.
In this way, the control device can finely set the upper limit injection amount according to the atmospheric pressure.

According to another aspect of the present disclosure, a control device included in the above engine system is provided.

In this way, it is possible to prevent the supercharging pressure from increasing excessively.
According to another aspect of the present disclosure, an engine control method includes obtaining an actual boost pressure of a supercharger that supercharges an engine, obtaining a reference maximum boost pressure of the supercharger, and obtaining the actual boost pressure of a supercharger that supercharges an engine. The upper limit injection amount of the engine is set according to the smaller boost pressure between the boost pressure and the reference maximum boost pressure.

In this way, it is possible to prevent the supercharging pressure from increasing excessively.

According to this invention, even if the actual boost pressure increases excessively due to a malfunction in the engine system, the lower of the standard maximum boost pressure and the actual boost pressure will be used. Set the corresponding upper limit injection amount. Therefore, for example, even if the actual boost pressure increases excessively and becomes larger than the reference maximum boost pressure, the upper limit injection amount corresponding to the reference maximum boost pressure can be set. Therefore, the injection amount can be appropriately suppressed, and as a result, the supercharging pressure can be prevented from increasing excessively.

1 is a diagram showing a schematic configuration of an engine system according to the present embodiment. It is a figure showing a variable nozzle mechanism. It is a figure showing a variable nozzle mechanism. It is a figure for explaining operation of a plurality of vanes. It is a functional block diagram of a control device. It is a figure which shows typically an example of a 1st map. It is a figure which shows typically an example of a 2nd map. 5 is a flowchart showing control processing of the control device 200. FIG. It is a figure which shows typically an example of a 3rd map. FIG. 3 is a diagram showing the relationship between boost pressure and injection amount. FIG. 3 is a diagram showing the relationship between boost pressure and injection amount.

Embodiments of the present disclosure will be described below with reference to the drawings. In the following description, the same parts are given the same reference numerals. Their names and functions are also the same. Therefore, a detailed description thereof will not be repeated.

FIG. 1 is a diagram showing a schematic configuration of an engine system 1 and its control system according to the present embodiment. In this embodiment, an example in which the engine system 1 is installed in a vehicle will be described. In this embodiment, the engine system 1 will be described using a common rail diesel engine as an example, but it may be other types of engines (eg, a gasoline engine, etc.).

The engine system (internal combustion engine) 1 includes an engine 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 EGR device (exhaust recirculation system). device) 60, an air flow meter 104, an engine speed sensor 102, a boost pressure sensor 106, an atmospheric pressure sensor 108, and a control device 200.

Engine 10 includes a cylinder head 11, a cylinder 12, a piston 14, and an injector 16. The cylinder 12 is arranged below the cylinder head 11. The piston 14 is inserted into the cylinder 12 so as to be able to reciprocate up and down. A combustion chamber 15 is defined by a space surrounded by the top of the piston 14, the cylinder head 11, and the cylinder 12. The engine system 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 injection nozzle 16a of the injector 16 at a predetermined timing. The injector 16 supplies a commanded fuel injection amount into the cylinder 12 according to a control signal from the control device 200 . Further, the upper limit injection amount of the injector 16 is set by the control device 200.

The air cleaner 20 removes foreign matter from the air taken in from the outside of the engine system 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. Intake manifold 28 is connected to an intake port of cylinder 12 of engine 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.

Exhaust manifold 50 is connected to an exhaust port of cylinder 12 of engine 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 and the exhaust manifold 50 are connected by the EGR device 60 without going through the cylinder 12 of the engine 10. The EGR device 60 includes an EGR valve 62 and an EGR passage (reflux passage) 66. The EGR passage 66 connects the third intake pipe 27 and the exhaust manifold 50. The EGR valve 62 is provided in the middle of 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 (exhaust path) is returned to the intake manifold 28 (intake path) as EGR gas via the EGR device 60, thereby lowering the combustion temperature in the cylinder 12 and reducing the amount of NOx produced. be done.

The supercharger 30 supercharges the engine 10. The supercharger 30 includes a compressor 32, a turbine 36, a variable nozzle mechanism (variable flow rate device) 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 exhaust 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 will be described as a vane opening degree) by rotating each of the plurality of vanes. The actuator 44 changes the vane 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 vane opening degree of the variable nozzle mechanism 40, the flow path of the exhaust gas 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.

2 and 3 are diagrams showing an example of the configuration of the variable nozzle mechanism 40. FIG. 2 is a view of the variable nozzle mechanism 40 seen from the left in FIG. FIG. 3 is a view 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 and 3, the variable nozzle mechanism 40 includes a plurality of vanes 67, a nozzle plate 69, and a unison ring 71. The plurality of vanes 67 are arranged at the exhaust inflow portion on the outer periphery of the turbine wheel 38 . The nozzle plate 69 holds the plurality of vanes 67 so as to be able to swing around the plurality of shafts 68 . Unison ring 71 rotates shafts 68 using arms 70 fixed to the ends 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, when the arm 72b is swung in the direction shown by the arrow by the link mechanism 72, the unison ring 71 is rotated in the direction shown by the arrow, that is, counterclockwise in FIG. 2 and clockwise in FIG. rotate around. 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 and clockwise in FIG. 3. Therefore, the opening degree of the vane 67 is controlled to the closed side (so that the gap between two adjacent vanes becomes narrower). Further, when the arm 72b is swung in the direction opposite to the arrow, the opening degree of the vane 67 is controlled to the opening side (so that the gap between two adjacent vanes widens).

FIG. 4 is a diagram for explaining the operation of the plurality of vanes 67 in the variable nozzle mechanism 40. As shown in FIG. 4, a rectangular opening whose side is a straight line shown by the solid line in FIG. 4 is formed in the gap between the vane 67a and the adjacent vane 67b. Similar openings are formed between each vane of the variable nozzle mechanism 40. The opening area is represented by the sum of the areas of the openings between the vanes. When the opening area is large (when the opening degree of the plurality of vanes 67 is large, for example, when the plurality of vanes 67 are in the state shown by the broken line), the flow velocity of the exhaust gas supplied to the turbine wheel 38 increases. On the other hand, when the opening area is small (when the opening degree of the plurality of vanes 67 is small, for example, when the plurality of vanes 67 are in a solid line state), the flow velocity of the exhaust gas supplied to the turbine wheel 38 decreases.

Returning to FIG. 1, the engine rotation speed sensor 102 detects the rotation speed (rotational speed) of the crankshaft, which is the output shaft of the engine system 1, as the engine rotation speed. Engine rotation speed sensor 102 transmits a signal indicating the detected engine rotation speed to 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 within the intake manifold 28 as the current actual boost pressure (hereinafter also referred to as "actual boost pressure"). Boost pressure sensor 106 transmits a signal indicating the detected actual boost pressure to control device 200.

The atmospheric pressure sensor 108 detects the atmospheric pressure around the engine system 1 (for example, the atmospheric pressure around the vehicle in which the engine system 1 is installed). Atmospheric pressure sensor 108 transmits a signal indicating the detected atmospheric pressure to control device 200 .

Control device 200 controls the operation of engine system 1 . The control device 200 includes a CPU (Central Processing Unit) 201 that performs various processes, a ROM (Read Only Memory) that stores programs and data, and a RAM (Random Access Memory) that stores the processing results of the CPU. 202 (storage device) 202, and an input/output port (not shown) for exchanging information with the outside. The above-mentioned sensors (eg, engine speed sensor 102, air flow meter 104, boost pressure sensor 106, atmospheric pressure sensor 108, etc.) are connected to the input port. 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 system 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).

[Functional block diagram of control device]
FIG. 5 is a functional block diagram of the control device 200. The control device 200 includes an acquisition section 202, a selection section 204, a setting section 206, and a storage section 208. The storage unit 208 is configured by, for example, the above-mentioned ROM.

The acquisition unit 202 acquires the engine rotation speed by receiving a signal indicating the engine rotation speed from the engine rotation speed sensor 102 . Further, the acquisition unit 202 acquires the atmospheric pressure by receiving a signal indicating the atmospheric pressure from the atmospheric pressure sensor 108 . The acquisition unit 202 acquires the reference maximum boost pressure based on the first map, the engine speed, and the atmospheric pressure. Here, the reference maximum boost pressure is the maximum boost pressure (upper limit boost pressure) when no abnormality occurs in the plurality of vanes 67. In other words, the reference maximum boost pressure is the maximum boost pressure at which the engine system 1 can operate safely.

FIG. 6 is a diagram schematically showing an example of the first map. The first map is typically a map that is created in advance in a state where no abnormality has occurred in the plurality of vanes 67. In the first map of FIG. 6, the horizontal axis shows the engine rotation speed, and the vertical axis shows the reference maximum boost pressure. In the first map, a graph showing the relationship between engine speed and reference maximum boost pressure is defined. In the first map, a plurality of graphs (four graphs in the example of FIG. 6) are further defined according to the value of the atmospheric pressure around the engine system 1. In FIG. 6, graph A shows the case where the atmospheric pressure is 101 kPa, graph B shows the case where the atmospheric pressure is 90 kPa, graph C shows the case where the atmospheric pressure is 80 kPa, and graph D shows the case where the atmospheric pressure is 70 kPa. Indicates the case where In the example of FIG. 6, it is specified that the reference maximum boost pressure increases as the atmospheric pressure increases, provided the engine speed is the same. The reason for this is that the lower the atmospheric pressure around the engine system 1, the more the temperature of the exhaust gas after being supercharged by the supercharger 30 tends to rise. Therefore, in order to protect the supercharger 30, the reference maximum boost pressure is set to be lower as the atmospheric pressure around the engine system 1 is lower.

The acquisition unit 202 identifies a graph close to the acquired atmospheric pressure among the graphs A to D in FIG. Furthermore, the acquisition unit 202 determines the reference maximum boost pressure corresponding to the engine speed with reference to the specified graph. The reference maximum boost pressure determined (acquired) by the acquisition unit 202 is output to the selection unit 204.

Further, the selection unit 204 obtains the actual boost pressure by receiving a signal indicating the actual boost pressure from the boost pressure sensor 106 . The selection unit 204 selects the smaller boost pressure between the actual boost pressure output from the boost pressure sensor 106 and the reference maximum boost pressure output from the acquisition unit 202. The selection unit 204 outputs the supercharging pressure selected by the selection unit 204 to the setting unit 206.

The setting unit 206 determines the upper limit injection amount based on the second map, the engine speed, and the boost pressure output from the acquisition unit 202. Here, the upper limit injection amount is an injection amount that satisfies both the first condition and the second condition. The first condition is a condition under which no undesirable event occurs from the viewpoint of environmental protection. The second condition is a condition under which undesirable events do not occur from the viewpoint of protecting the engine system 1.

The first condition is, for example, that a large amount of black smoke, which is undesirable from the viewpoint of environmental protection, is not discharged outside the vehicle. Additionally, generally speaking, when the injection amount increases, the exhaust temperature increases, which may cause the engine system 1 to malfunction. The second condition is that the engine system 1 does not fail.

FIG. 7 is a diagram schematically showing an example of the second map. The second map is typically a map that is created in advance with no abnormality occurring in the plurality of vanes 67. In the second map of FIG. 7, the horizontal axis indicates the supercharging pressure selected by the selection unit 204 (the supercharging pressure output from the selection unit 204), and the vertical axis indicates the upper limit injection amount. Hereinafter, the selected supercharging pressure will also be referred to as "selected supercharging pressure." The selected boost pressure corresponds to "the smaller boost pressure between the actual boost pressure and the reference maximum boost pressure" in the present disclosure. In the second map, a graph showing the relationship between the selected supercharging pressure and the upper limit injection amount is defined. In the second map, a plurality of graphs (three graphs in the example of FIG. 6) are further defined according to the current engine speed value. In FIG. 6, graph A shows the case where the engine speed is 1000 rpm, graph B shows the case where the engine speed is 900 rpm, and graph C shows the case where the engine speed is 800 rpm. In the example of FIG. 7, the upper limit injection amount is defined to vary depending on the engine speed. In the example of FIG. 7, it is specified that the upper limit injection amount becomes larger as the engine speed increases, provided that the selected supercharging pressure is the same.

The setting unit 206 identifies a graph close to the acquired engine rotation speed among graphs A to C in FIG. 7. Further, the setting unit 206 determines the upper limit injection amount corresponding to the selected supercharging pressure with reference to the specified graph. The setting unit 206 sets the upper limit injection amount to the injector 16 by transmitting a signal indicating the determined upper limit injection amount to the injector 16. When the amount of operation of the accelerator pedal is increased by the driver of the vehicle, the boost pressure increases and the injection amount increases. When the injection amount reaches the upper limit injection amount, the injector 16 controls the injection amount to reduce the injection amount so that the injection amount becomes smaller than the upper limit injection amount, or to maintain the injection amount.

[Flow of processing of control device]
FIG. 8 is a flowchart showing the control processing of the control device 200. The control processing program shown in the flowchart of FIG. 8 is stored in a predetermined storage area (for example, the above-mentioned ROM). The process shown in FIG. 8 is realized by the CPU reading the program from the storage area and repeatedly executing it at a predetermined period.

In step S2, control device 200 obtains a reference maximum boost pressure based on the first map shown in FIG. Next, in step S4, the control device 200 acquires the actual boost pressure from the boost pressure sensor 106. Next, in step S6, control device 200 selects the smaller boost pressure between the actual boost pressure and the reference maximum boost pressure. Next, in step S8, the control device 200 sets an upper limit injection amount according to the boost pressure selected in step S8.

As described above, in the engine system 1, the vane 67 included in the variable nozzle mechanism 40 changes the flow velocity of the exhaust gas that operates the turbine 36. By the way, the boost pressure may increase excessively due to a malfunction in the engine system 1 or the like. This case is, for example, a case where impurities (for example, unburned fuel) adhere to the vane 67 for a long time at a low exhaust temperature. Impurities can also be, for example, soot. This also includes a cause in which the vane 67 does not operate on the shaft 68 due to an external impact or the like. In this case, when the driver of the vehicle depresses the accelerator pedal, the amount of injection from the vehicle increases. Along with this, the temperature of the exhaust manifold gas, the pressure of the exhaust manifold gas, the rotational speed of the turbine wheel 38, etc. increase, and the supercharging pressure also increases. Here, the engine system 1 controls the temperature of the exhaust manifold gas (gas in the exhaust manifold 50), the pressure of the exhaust manifold gas, the rotation speed of the turbine wheel 38, and the opening degree of the vanes to prevent an excessive increase in boost pressure. needs to be made larger. However, since the vanes are fixed, the degree of opening of the vanes cannot be increased, and as a result, a problem may occur in which the supercharging pressure increases excessively. If the boost pressure increases excessively, problems with the engine system will occur. The malfunction of the engine system 1 is, for example, a failure of the supercharger 30, and more specifically, a failure of the connecting shaft 42.

Therefore, the selection unit 204 (see FIG. 5) selects between the reference maximum boost pressure when no abnormality occurs in the engine system 1 (for example, the vane 67) and the actual boost pressure (actual boost pressure). Compare size. Then, the control device 200 specifies the smaller boost pressure between the reference maximum boost pressure and the actual boost pressure, and sets the upper limit injection amount corresponding to the specified boost pressure. According to this configuration, when the actual boost pressure is equal to or lower than the reference maximum boost pressure, it is highly likely that no abnormality has occurred in the vane 67. In this case, an upper limit injection amount corresponding to the actual boost pressure is set. Therefore, the upper limit injection amount corresponding to the actual boost pressure in a state where no abnormality has occurred in the vane 67 is set.

On the other hand, if the actual boost pressure is higher than the reference maximum boost pressure, there is a high possibility that an abnormality has occurred in the vane 67. In this case, an upper limit injection amount corresponding to an excessively large actual boost pressure (that is, an excessively large upper limit injection amount) is not set, but an upper limit injection amount corresponding to the reference maximum boost pressure is set. Therefore, since it is possible to prevent the injection amount from the vehicle from becoming excessively large, it is possible to suppress the supercharging pressure from increasing excessively. Further, by suppressing the supercharging pressure from increasing excessively, failure of the supercharger 30 can be suppressed.

It is also conceivable to adopt "a configuration in which unburned fuel (impurities) adhering to the vane 67 is detected and the unburned fuel is dissolved." However, with this configuration, it takes time to perform the process of detecting unburned fuel and the process of dissolving unburned fuel, and the supercharging pressure increases excessively while these processes are being performed. , a problem may arise in which the supercharger 30 breaks down. In contrast, in the engine system 1 of the present embodiment, it is possible to suppress the supercharging pressure from increasing excessively without executing the process of detecting unburned fuel adhering to the vanes 67. Therefore, occurrence of such problems can be suppressed.

Further, the control device 200 acquires the atmospheric pressure around the engine system 1, and acquires the reference maximum boost pressure based on the atmospheric pressure (see FIG. 6). Therefore, the control device 200 can obtain the reference maximum boost pressure in consideration of the atmospheric pressure around the engine system 1.

Further, the control device 200 obtains a reference maximum boost pressure based on the rotation speed of the engine 10 (see FIG. 6). Therefore, the control device 200 can obtain the reference maximum boost pressure in consideration of the rotation speed of the engine 10.

[Other embodiments]
(1) In the example of FIG. 6 described above, the environment information indicating the environment of the engine system 1 is the atmospheric pressure around the engine system 1. However, the environmental information may be other information. The environmental information may be, for example, the temperature around the engine system 1. In this embodiment, a temperature sensor 109 (see FIG. 1) is used instead of the atmospheric pressure sensor 108. Temperature sensor 109 is a sensor that detects the temperature around engine system 1 . The temperature detected by the temperature sensor 109 is output to the acquisition unit 202 (see FIG. 5). FIG. 9 is a diagram schematically showing an example of the third map used in this embodiment. The third map is typically a map that is created in advance with no abnormality occurring in the plurality of vanes 67. In the third map of FIG. 9, the horizontal axis shows the engine speed, and the vertical axis shows the reference maximum boost pressure. In the third map, a graph showing the relationship between engine speed and reference maximum boost pressure is defined. In the third map, a plurality of graphs (four graphs in the example of FIG. 9) are further defined according to the temperature value around the engine system 1. In Figure 9, graph A shows the case where the temperature is 20 degrees, graph B shows the case where the temperature is 40 degrees, graph C shows the case where the temperature is 50 degrees, and graph D shows the case where the temperature is 80 degrees. Indicates the case where In the example of FIG. 9, it is specified that the standard maximum boost pressure increases as the temperature decreases, provided the engine speed is the same. The reason for this is that the higher the temperature around the engine system 1 is, the more the temperature of the exhaust gas after supercharging by the supercharger 30 tends to rise. Therefore, in order to protect the supercharger 30, the reference maximum boost pressure is set to be lower as the temperature around the engine system 1 becomes higher.

The acquisition unit 202 identifies a graph close to the acquired temperature among the graphs A to D in FIG. Furthermore, the acquisition unit 202 determines the reference maximum boost pressure corresponding to the engine speed with reference to the specified graph. The reference maximum boost pressure determined (acquired) by the acquisition unit 202 is output to the selection unit 204.

In this embodiment, the control device 200 can obtain the reference maximum boost pressure based on the temperature around the engine system 1 (taking into account the atmospheric pressure around the engine system 1). .

(2) In the above embodiment, the second map showing the relationship between the selected supercharging pressure and the upper limit injection amount has the relationship shown in FIG. 7. However, this relationship may be any other relationship. FIG. 10 is a diagram showing a fourth map showing other relationships.

In FIG. 10, a graph A when the atmospheric pressure is 90 kPa and a graph B when the atmospheric pressure is 101 kPa are shown. In the example of FIG. 10, a threshold value is set for the selected boost pressure. For graph A, a threshold value P1 is set, and for graph B, a threshold value P2 is set. Further, the threshold value P2 is set to be larger than the threshold value P1.

Regarding graph A, when the selected supercharging pressure is equal to or less than the threshold value P1, the upper limit injection amount is defined according to the selected supercharging pressure. In the example of FIG. 10, it is specified that the higher the selected supercharging pressure is, the higher the upper limit injection amount is. Furthermore, at a selected supercharging pressure greater than the threshold P1, a constant upper limit injection amount Q1 is defined regardless of the value of the selected supercharging pressure.

Further, regarding graph B, at a selected supercharging pressure equal to or lower than the threshold P2, an upper limit injection amount is defined according to the selected supercharging pressure. In the example of FIG. 10, it is specified that the higher the selected supercharging pressure is, the higher the upper limit injection amount is. Furthermore, for a selected supercharging pressure greater than the threshold P2, a constant upper limit Q2 is defined regardless of the value of the selected supercharging pressure.

The setting unit 206 identifies a graph that is close to the acquired atmospheric pressure among graphs A and B in FIG. 10 . Further, the setting unit 206 determines the upper limit injection amount corresponding to the selected supercharging pressure with reference to the specified graph.

That is, when the setting unit 206 identifies graph A, for example, and the selected supercharging pressure is less than or equal to the threshold value P1, the setting unit 206 sets the upper limit injection amount according to the selected supercharging pressure. On the other hand, when the selected supercharging pressure is larger than the threshold value P1, a fixed upper limit injection amount Q1 is set.

By providing a threshold value for the selected supercharging pressure in this way, it is possible to prevent an excessively large upper limit injection amount from being set. Further, the threshold value is set to differ depending on the value of atmospheric pressure. In the example of FIG. 10, the threshold value is specified to become larger as the atmospheric pressure becomes larger. Thereby, the setting unit 206 can finely set the upper limit injection amount according to the atmospheric pressure.

FIG. 11 is a diagram showing a fifth map showing other relationships. In FIG. 11, graph A when the temperature is 40 degrees and graph B when the temperature is 20 degrees are shown. In the example of FIG. 11, a threshold value is set for the selected boost pressure. For graph A, a threshold value P1 is set, and for graph B, a threshold value P2 is set. Further, the threshold value P2 is set to be larger than the threshold value P1.

As shown in FIGS. 10 and 11, the settings are different depending on the environment of the engine system 1. In the example of FIG. 10, the environment is atmospheric pressure, and in the example of FIG. 11, it is temperature. Thereby, the setting unit 206 can finely set the upper limit injection amount according to the environment of the engine system 1. Furthermore, the graphs shown in FIGS. 10 and 11 may be defined for each engine speed (see FIG. 7).

(3) All parameters used in the above-described embodiment (engine speed, atmospheric pressure around the engine system 1, actual boost pressure, and temperature around the engine system 1) are detected by sensors. explained. However, at least one of all these parameters may be estimated by an estimator included in the control device 200, for example. For example, the estimation unit may estimate the engine rotation speed based on the turbine rotation speed.

Note that the above-described modifications may be implemented in whole or in part in combination.
The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and it is intended that all changes within the meaning and range equivalent to the claims are included.

1 engine system, 10 engine, 11 cylinder head, 12 cylinder, 14 piston, 15 combustion chamber, 16 injector, 16a injection nozzle, 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 Removal filter, 58 Catalyst, 62 Valve, 66 Passage, 67 Vane, 68 Shaft, 69 Nozzle plate, 70, 72b Arm, 71 Unison ring, 72 Link mechanism, 72a Rotating shaft, 102 Engine speed sensor, 104 Air flow meter, 106 Boost pressure sensor, 108 Barometric pressure sensor, 109 Temperature sensor, 200 Control device, 202 Acquisition unit, 204 Selection unit, 206 Setting unit, 208 Storage unit .

Claims (8)

engine and
a supercharger that supercharges the engine;
and a control device that executes a setting process for setting the upper limit injection amount of the engine every predetermined period ,
The control device includes:
Obtaining the actual boost pressure of the supercharger,
Obtaining the reference maximum boost pressure of the supercharger,
If the smaller boost pressure between the actual boost pressure and the reference maximum boost pressure is below the threshold, the corresponding upper limit injection amount according to the smaller boost pressure is set as the upper limit injection amount. Execute the configuration process to set it as
A specific injection amount is defined that is smaller than the injection amount corresponding to the smaller boost pressure when the smaller boost pressure is the threshold value,
The control device further includes:
In a setting process subsequent to the setting process in which the corresponding upper limit injection amount is set, if the smaller boost pressure becomes larger than the threshold value, a setting process is executed to set the specific injection amount as the upper limit injection amount. The engine system. The engine system according to claim 1, wherein the control device sets the threshold value to be larger when the atmospheric pressure around the engine system is high than when the atmospheric pressure around the engine system is low. The engine system according to claim 1, wherein the control device sets the threshold value to be larger when the temperature around the engine system is low than when the temperature around the engine system is high. The control device includes:
obtaining environmental information indicating the environment of the engine system;
The engine system according to any one of claims 1 to 3 , wherein the reference maximum boost pressure is obtained based on the environmental information. The engine system according to claim 4 , wherein the environmental information includes a temperature around the engine system or an air pressure around the engine system. The engine system according to any one of claims 1 to 5 , wherein the control device obtains the reference maximum boost pressure based on the rotation speed of the engine. A control device included in the engine system according to any one of claims 1 to 6. Obtaining the actual boost pressure of the supercharger that supercharges the engine;
Obtaining a reference maximum boost pressure of the supercharger;
executing a setting process for setting an upper limit injection amount of the engine at every predetermined cycle;
Executing the setting process includes:
If the smaller boost pressure between the actual boost pressure and the reference maximum boost pressure is below the threshold, the corresponding upper limit injection amount according to the smaller boost pressure is set as the upper limit injection amount. including performing a configuration process to configure as
A specific injection amount is defined that is smaller than the injection amount corresponding to the smaller boost pressure when the smaller boost pressure is the threshold value,
Executing the setting process includes:
In a setting process subsequent to the setting process in which the corresponding upper limit injection amount is set, if the smaller boost pressure becomes larger than the threshold value, a setting process is executed to set the specific injection amount as the upper limit injection amount. An engine control method including :

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