Engine device

Abstract

Provided is an engine device capable of operating while avoiding abnormal combustion when a gaseous fuel and a liquid fuel are introduced. An engine device (1) for driving by injecting at least one of a gaseous fuel and a liquid fuel into a combustion chamber (12a) of an engine (2) is provided with a dangerous region in which abnormal combustion can be predicted in advance with respect to the co-combustion rate of the gaseous fuel included in the fuel injected into the combustion chamber (12a), and avoids the dangerous region when the engine (2) is operated. For example, when the engine device (1) operates the engine (2) while changing the co-combustion rate, the engine device (1) executes avoidance control for avoiding the dangerous region. For example, the engine device (1) sets a danger region in advance in accordance with the relationship between the engine load and the gas fuel co-combustion rate.

Description

Technical Field

[0001] The present invention relates to an engine device which is driven by injecting at least one of gas fuel and liquid fuel into a combustion chamber. Background Art

[0002] Conventionally, some engine devices are driven by injecting at least one of a gas fuel such as hydrogen and a liquid fuel such as light oil or heavy oil into a combustion chamber in a cylinder.

[0003] For example, some engine devices operate in either a gas mode in which gas fuel is fed into a combustion chamber to drive the engine, or a diesel mode in which liquid fuel is fed into the combustion chamber to drive the engine. In such an engine device, when the operation mode is switched between the gas mode and the diesel mode, the mixing ratio of the gas fuel contained in the fuel fed into the combustion chamber changes.

[0004] In addition, some engine devices operate in a co-firing mode in which both gas fuel and liquid fuel are introduced into a combustion chamber to drive the engine as another operation mode.

[0005] For example, when the engine device disclosed in Patent Document 1 switches the operating mode from one of the gas mode and the diesel mode to the other, the supply amount of the first fuel injected into the switched operating mode is increased to a switching threshold by monotonically increasing incremental control and then controlled by speed control based on the engine speed.

[0006] In addition, the operation control device of the internal combustion engine disclosed in Patent Document 2 includes: a fuel property estimation unit that estimates the composition ratio of the fuel supplied to the internal combustion engine; and an operation restriction unit that determines an operation region in which abnormal combustion of the internal combustion engine is likely to occur based on the composition ratio of the fuel estimated by the fuel property estimation unit, and restricts the operation of the internal combustion engine in the operation region in which abnormal combustion of the internal combustion engine is likely to occur. Here, the composition ratio of the fuel is the ratio of butane and propane contained in liquefied petroleum gas.

[0007] Patent Document 1: Japanese Patent No. 6594714

[0008] Patent Document 2: Japanese Patent Application Publication No. 2008-057500

[0009] In an engine device that can be driven by feeding gas fuel and liquid fuel into a combustion chamber, when the operation mode is switched between the gas mode and the diesel mode, or when the engine is operated in the mixed combustion mode, the mixed combustion ratio of the gas fuel contained in the fuel fed into the combustion chamber is changed to a predetermined target mixed combustion ratio. At this time, abnormal combustion such as pre-ignition and knocking may occur locally in a certain area of ​​the engine depending on the mixed combustion ratio. However, it is difficult to avoid such abnormal combustion in the prior art. Summary of the invention

[0010] An object of the present invention is to provide an engine device capable of operating while avoiding abnormal combustion when gas fuel and liquid fuel are fed.

[0011] In order to solve the above-mentioned problems, the engine device of the present invention is an engine device that is driven by introducing at least one of gas fuel and liquid fuel into the combustion chamber, and is characterized in that a dangerous area in which abnormal combustion can be predicted is pre-set for the mixing ratio of the above-mentioned gas fuel contained in the fuel introduced into the above-mentioned combustion chamber, so that the above-mentioned dangerous area is avoided when the engine is running.

[0012] According to the present invention, it is possible to provide an engine device that can be operated while avoiding abnormal combustion when gas fuel and liquid fuel are fed. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a left side view showing the engine device according to the embodiment of the present invention.

[0014] Figure 2 This is a graph showing the relationship between the gas fuel combustion rate and the maximum pressure of the combustion chamber in the engine device.

[0015] Figure 3 This is a graph showing the relationship between the gas fuel combustion ratio and the pre-ignition frequency in the engine device.

[0016] Figure 4 It is a plan view showing a danger zone map showing a danger zone with respect to the relationship between the gas fuel combustion ratio and the engine load in the engine device according to the embodiment of the present invention.

[0017] Figure 5 It is a plan view showing a danger zone map showing a danger zone with respect to the relationship between the gas fuel combustion ratio and the engine load in the engine device according to the first modified example of the present invention.

[0018] Figure 6 This is a graph showing the relationship between the gas fuel mixing rate, the maximum temperature of the combustion chamber, and the excess air rate of the gas fuel in the engine device.

[0019] Description of Reference Numerals

[0020] 1…engine device; 2…engine; 3…intake passage; 4…exhaust passage; 4a…exhaust bypass flow path; 4b…exhaust bypass valve; 5…supercharger; 5a…turbine; 5b…compressor; 6…intercooler; 7…first recirculation device; 7a…first recirculation cooler; 7b…first recirculation valve; 8…second recirculation device; 8a…second recirculation cooler; 8b…second recirculation valve; 9…control unit; 11…cylinder block; 12…cylinder; 12a…combustion chamber; 13…cylinder; 14…piston; 15…cylinder head; 16…gas fuel injection unit; 17…liquid fuel injection unit; 18…connecting rod; 19…crankshaft; 20…speed sensor; 21…torque sensor; 22…intake port; 23…exhaust port; 24…intake valve; 25…exhaust valve. DETAILED DESCRIPTION

[0021] An engine device 1 according to an embodiment of the present invention will be described with reference to the accompanying drawings. Figure 1 As shown, the engine device 1 includes an engine 2 , an intake passage 3 , an exhaust passage 4 , a supercharger 5 , an intercooler 6 , a first recirculation device 7 , a second recirculation device 8 , and a control unit 9 .

[0022] In particular, in the present embodiment, the engine device 1 is configured to be driven by injecting gas fuel such as hydrogen and liquid fuel such as light oil and heavy oil into the combustion chamber 12a of the engine 2, and is provided with a gas fuel injection unit 16 for injecting gas fuel and a liquid fuel injection unit 17 for injecting liquid fuel. The engine device 1 is configured to switch to any one of the operating modes of a gas mode in which gas fuel is injected into the combustion chamber 12a for driving and a diesel mode in which liquid fuel is injected into the combustion chamber 12a for driving.

[0023] The engine 2 is configured by including a plurality of cylinders 12 in a cylinder block 11. Figure 1 Only one cylinder 12 is shown in the figure. Figure 1 As shown, each cylinder 12 is composed of a cylinder 13, a piston 14, and a cylinder head 15. Each cylinder 12 is provided with a gas fuel injection portion 16 and a liquid fuel injection portion 17.

[0024] The cylinder 13 is formed in a cylindrical shape, for example, in the cylinder body 11, and the piston 14 is slidably accommodated in the cylinder 13. The cylinder head 15 is attached to the upper side of the cylinder 13, and the cylinder 13 and the cylinder head 15 form a combustion chamber 12a inside.

[0025] A crankshaft 19 is connected to the piston 14 below the cylinder 13 via a connecting rod 18 , and the reciprocating motion of the piston 14 is converted into the rotational motion of the crankshaft 19 via the connecting rod 18 .

[0026] The cylinder 13 is provided with a rotation speed sensor 20 such as an encoder for detecting the rotation speed of the crankshaft 19, that is, the rotation speed of the engine 2, and the rotation speed sensor 20 sends the detection result to the control unit 9. The cylinder 13 is provided with a torque sensor 21 for detecting the engine load (engine torque) of the engine 2 near the crankshaft 19, and the torque sensor 21 sends the detection result to the control unit 9.

[0027] The cylinder head 15 has an intake port 22 and an exhaust port 23 communicating with the combustion chamber 12a of the cylinder 13, and includes an intake valve 24 and an exhaust valve 25 that respectively open and close the intake port 22 and the exhaust port 23 with respect to the combustion chamber 12a.

[0028] The intake port 22 is connected to the intake passage 3, and the air supplied from the intake passage 3 is introduced into the combustion chamber 12a. The exhaust port 23 is connected to the exhaust passage 4, and the exhaust gas generated in the combustion chamber 12a is discharged into the exhaust passage 4. By opening the intake valve 24, the mixed gas of fuel gas and air can be sucked into the combustion chamber 12a through the intake port 22, and on the other hand, by opening the exhaust valve 25, the exhaust gas generated in the combustion chamber 12a can be discharged through the exhaust port 23.

[0029] also, Figure 1 , the intake passage 3 and the intake port 22 are directly connected. However, in order to connect the intake passage 3 and the intake ports 22 of the plurality of cylinders 12, an intake manifold having a branch flow path branching from the intake passage 3 to the plurality of cylinders 12 may be provided between the intake passage 3 and the engine 2. Figure 1 The figure shows an example in which the exhaust passage 4 and the exhaust port 23 are directly connected, but when the exhaust passage 4 and the exhaust ports 23 of multiple cylinders 12 are connected, an exhaust manifold having a branch flow path branching from the exhaust passage 4 to the multiple cylinders 12 can be provided between the exhaust passage 4 and the engine 2.

[0030] In each cylinder 12, a gas fuel injection unit 16 is provided at an intake port 22, and is controlled by a control unit 9 to inject gas fuel supplied from a gas fuel tank (not shown) into the intake port 22. A mixed gas of air supplied from the intake passage 3 and gas fuel supplied from a gas fuel tank (not shown) is supplied to the combustion chamber 12a from the intake port 22. The gas fuel injection unit 16 is composed of, for example, a gas intake valve, a gas injector, etc. The gas fuel injection unit 16 is controlled by the control unit 9 in terms of injection pressure, injection timing, etc. of the gas fuel.

[0031] In each cylinder 12, a liquid fuel injection unit 17 is provided in the cylinder head 15, and is controlled by the control unit 9 to inject liquid fuel supplied from a liquid fuel tank (not shown) into the combustion chamber 12a below the cylinder head 15. The liquid fuel injection unit 17 is composed of an injector, etc. The liquid fuel injection unit 17 is controlled by the control unit 9 with respect to the injection pressure, injection period, injection number, etc. of the liquid fuel.

[0032] The ignition in the combustion chamber 12 a of each cylinder 12 may be performed by a micro-pilot method in which a small amount of liquid fuel is injected from the liquid fuel injection portion 17 , or may be performed by a spark ignition method in which each cylinder 12 is provided with an ignition plug.

[0033] The intake passage 3 is connected to the intake port 22 of the cylinder 12 of the engine 2, and compressed and cooled air is supplied to each cylinder 12 through the intake port 22. A supercharger 5 and an intercooler 6 are provided in order from the upstream side in the intake direction of the intake passage 3. In addition, an air filter (not shown) for purifying and introducing fresh air may be provided at the upstream end of the intake passage 3 in the intake direction.

[0034] The exhaust passage 4 is connected to the exhaust port 23 of each cylinder 12 of the engine 2, and exhaust gas generated in each cylinder 12 is discharged through the exhaust port 23. The exhaust passage 4 is provided with an exhaust bypass flow path 4a that connects a portion on the upstream side of the supercharger 5 in the exhaust direction and a portion on the downstream side of the supercharger 5 in the exhaust direction, and an exhaust bypass valve 4b for adjusting the exhaust gas flow rate is provided in the exhaust bypass flow path 4a.

[0035] The exhaust bypass valve 4b is controlled and the opening degree is adjusted by the control unit 9. According to the opening degree of the exhaust bypass valve 4b, the flow rate of the exhaust gas flowing into the supercharger 5 is adjusted, thereby adjusting the compression amount of the air by the supercharger 5. That is, by adjusting the opening degree of the exhaust bypass valve 4b, the flow rate of the air supplied from the intake passage 3 to the intake port 22 can be adjusted.

[0036] The supercharger 5 compresses the air flowing through the intake passage 3 and sends it to the downstream side in the intake direction, and the intercooler 6 cools the air compressed by the supercharger 5. The supercharger 5 includes a turbine 5a and a compressor 5b. The turbine 5a is arranged in the exhaust passage 4, and the compressor 5b is arranged in the intake passage 3. The turbine 5a is rotated by the exhaust gas flowing through the exhaust passage 4, and the compressor 5b is driven by the rotational force of the turbine 5a, thereby compressing the air flowing through the intake passage 3.

[0037] The first recirculation device 7 recirculates the exhaust gas flowing into the exhaust passage 4 and supplies it to the intake passage 3. The first recirculation device 7 is connected to the exhaust passage 4 at a position downstream of the supercharger 5 (turbine 5a) in the exhaust direction, and is connected to the intake passage 3 at a position upstream of the supercharger 5 (compressor 5b) in the intake direction.

[0038] The first recirculation device 7 is configured to include, for example, a first recirculation cooler 7a and a first recirculation valve 7b. The first recirculation device 7 cools the exhaust gas flowing into the exhaust passage 4 by the first recirculation cooler 7a at a position downstream of the supercharger 5 in the exhaust direction and recirculates the exhaust gas, and supplies the exhaust gas to the intake passage 3 at a position upstream of the supercharger 5 in the intake direction. The first recirculation valve 7b is controlled by the control unit 9 and the opening degree is adjusted. The flow rate of the recirculated exhaust gas flowing into the intake passage 3 is adjusted according to the opening degree of the first recirculation valve 7b, so that the oxygen content of the air flowing into the intake passage 3 can be adjusted.

[0039] The second recirculation device 8 recirculates the exhaust gas flowing into the exhaust passage 4 and supplies it to the intake passage 3. The second recirculation device 8 is connected to the exhaust passage 4 at a position upstream of the supercharger 5 (turbine 5a) in the exhaust direction, and is connected to the intake passage 3 at a position downstream of the intercooler 6 in the intake direction.

[0040] The second recirculation device 8 is configured to include, for example, a second recirculation cooler 8a and a second recirculation valve 8b. The second recirculation device 8 cools the exhaust gas flowing into the exhaust passage 4 by the second recirculation cooler 8a at a position upstream of the supercharger 5 in the exhaust direction and recirculates the exhaust gas, and supplies the exhaust gas to the intake passage 3 at a position downstream of the intercooler 6 in the intake direction. The second recirculation valve 8b is controlled by the control unit 9 and the opening degree is adjusted. The flow rate of the recirculated exhaust gas flowing into the intake passage 3 is adjusted according to the opening degree of the second recirculation valve 8b, so that the oxygen content of the air flowing into the intake passage 3 can be adjusted.

[0041] The control unit 9 is a computer such as an ECU (Engine Control Unit) that controls the operation of the engine 2, and includes a CPU, ROM, RAM, etc., and is configured to control various parts of the engine 2. The control unit 9 can store various programs for controlling the engine 2, and control the engine 2 by reading and executing the programs.

[0042] In addition, the engine device 1 can be switched to operate in either a gas mode in which gas fuel is injected into the combustion chamber 12a for driving, or a diesel mode in which liquid fuel is injected into the combustion chamber 12a for driving. The control unit 9 switches the operation mode automatically according to the load of the engine 2 or according to the operation performed by the user.

[0043] In the gas mode, the fuel injected into the combustion chamber 12a is the gas fuel injected by the gas fuel injection unit 16, but also contains a very small amount of liquid fuel injected as an ignition agent by the liquid fuel injection unit 17, that is, the gas fuel contained in the fuel injected into the combustion chamber 12a has a combustion ratio of about 100%. In the diesel mode, the fuel injected into the combustion chamber 12a is the liquid fuel injected by the liquid fuel injection unit 17, that is, the gas fuel contained in the fuel injected into the combustion chamber 12a has a combustion ratio of 0%.

[0044] At this time, during the period from the time when the operating mode starts to switch from diesel mode to gas mode until the operating mode is completely switched, the control unit 9 controls the ratio of liquid fuel injected into the combustion chamber 12a in a manner that gradually decreases from 100% to 0%, and gradually increases the ratio of gas fuel from 0% to 100%, that is, controls the mixing rate of gas fuel.

[0045] In addition, during the period from the start of the operation mode switching from the gas mode to the diesel mode until the operation mode is completely switched, the control unit 9 controls the ratio of liquid fuel injected into the combustion chamber 12a in a manner that gradually increases from 0% to 100% and gradually decreases the ratio of gas fuel from 100% to 0%, that is, controls the mixing rate of the gas fuel.

[0046] That is, when the operation mode is switched between the gas mode and the diesel mode, the fuel injected into the combustion chamber 12a is a mixture of gas fuel and liquid fuel.

[0047] Figure 2 is a graph showing the maximum pressure of the combustion chamber 12a measured when the gas fuel combustion ratio is changed under a constant engine load. Figure 3 This is a graph showing the frequency of pre-ignition detected when the combustion ratio of the gas fuel is changed under a certain engine load. According to the above graph, when the combustion ratio is in a predetermined range, there is a tendency that the maximum pressure of the combustion chamber 12a becomes larger than the allowable pressure and the frequency of pre-ignition becomes relatively high, so such a range can be regarded as a dangerous range where abnormal combustion such as pre-ignition and knocking of the engine 2 can be predicted.

[0048] Therefore, when the control unit 9 operates the engine 2 while changing the mixing ratio of the gas fuel under a certain engine load, for example, when switching the operation mode, the control unit 9 executes avoidance control to avoid the dangerous area.

[0049] In the engine device 1, for such a change in the gas fuel combustion ratio, a dangerous area where abnormal combustion can be predicted is preset and stored in the control unit 9. For example, Figure 4As shown, a danger zone map showing a danger zone in which abnormal combustion can be predicted when the gas fuel mixing ratio is changed under a certain engine load is preset and stored in the control unit 9. In addition, the control unit 9 preferably stores the danger zone map in advance for various operating environments such as the air temperature sucked into the engine 2 (the ambient temperature of the engine device 1) and the oxygen excess ratio (the ratio of oxygen in the air corresponding to the ambient altitude of the engine device 1 such as a depression or a plateau).

[0050] As the avoidance control for avoiding the danger zone, the control unit 9, when changing the gas fuel combustion ratio, limits the change of the combustion ratio in a manner that does not enter the danger zone based on the danger zone map. For example, when the control unit 9 switches the operation mode under a specified engine load, it refers to the danger zone map to determine whether there is a danger zone of the gas fuel combustion ratio corresponding to the engine load. At this time, the control unit 9 detects the engine load through the torque sensor 21. In addition, the control unit 9 detects the operating environment such as air temperature and oxygen excess rate, obtains the danger zone map corresponding to the operating environment of the detection result, and refers to it.

[0051] If the above determination result is that there is no danger zone, the control unit 9 may not perform the avoidance control and completely switch the operation mode. On the other hand, if it is determined that there is a danger zone, the control unit 9 sets the upper limit or lower limit of the gas fuel mixing ratio change based on the danger zone as avoidance control, and controls the injection amount of the gas fuel of the gas fuel injection unit 16 and the injection amount of the liquid fuel of the liquid fuel injection unit 17.

[0052] For example, Figure 4 As shown, when the engine is operated at a predetermined engine load T1, the control unit 9 switches from the diesel mode to the gas mode and gradually increases the gas fuel combustion ratio, and reaches the dangerous area at the combustion ratio R1, so the upper limit of the change in the gas fuel combustion ratio is set to be less than the combustion ratio R1. In addition, when the control unit 9 switches from the gas mode to the diesel mode and gradually reduces the gas fuel combustion ratio, the dangerous area is reached at the combustion ratio R2, so the lower limit of the change in the gas fuel combustion ratio is set to be greater than the combustion ratio R2.

[0053] As described above, according to the present embodiment, the engine device 1 is an engine device 1 that is driven by injecting at least one of gas fuel and liquid fuel into the combustion chamber 12a of the engine 2, wherein a dangerous area in which abnormal combustion can be predicted is pre-set for the mixing ratio of the gas fuel contained in the fuel injected into the combustion chamber 12a, and avoidance control to avoid the dangerous area is performed while the mixing ratio is changed and the engine 2 is operated under a certain engine load.

[0054] Thus, when the gas fuel and the liquid fuel are introduced into the combustion chamber 12 a , the engine device 1 can be operated while avoiding abnormal combustion of the engine 2 caused by the mixed combustion ratio of the gas fuel.

[0055] Furthermore, according to the present embodiment, the engine device 1 sets a dangerous region in advance with respect to the relationship between the engine load and the gas fuel combustion ratio.

[0056] Thus, when the engine device 1 is operated at a predetermined engine load, the gas fuel combustion ratio corresponding to the engine load can be grasped, and the engine 2 can be operated while avoiding abnormal combustion by avoiding the gas fuel combustion ratio in the dangerous range.

[0057] Furthermore, according to the present embodiment, as avoidance control, the engine device 1 restricts the change in the combustion ratio of the gas fuel with respect to the dangerous region.

[0058] Thus, when the engine device 1 is operated at a predetermined engine load, the engine 2 can be operated while avoiding abnormal combustion by more reliably avoiding the range in which the combustion ratio of the gas fuel enters the dangerous region.

[0059] In addition, in the above-mentioned embodiment, the following example is described, that is, in the engine device 1, as an avoidance control for avoiding the dangerous area, the control unit 9 limits the change of the mixed combustion ratio in a manner not to enter the dangerous area based on the dangerous area map when changing the mixed combustion ratio of the gas fuel, but the present invention is not limited to this example.

[0060] As a first variation, the control unit 9 may also perform avoidance control by changing the operating conditions in a manner that cancels or alleviates the dangerous area for limiting the gas fuel co-combustion ratio. In other words, the control unit 9 performs control by changing the operating conditions in a manner that reduces the dangerous area. For example, Figure 4 The dangerous area map shown in FIG. 1 can be changed to the following by changing the operating conditions: Figure 5 Danger zone map with reduced danger zone shown.

[0061] In the engine device 1, when the engine 2 is operated while changing the gas fuel combustion ratio at a certain engine load, for example, when the operation mode is switched, the maximum temperature (combustion temperature) of the combustion chamber 12a and the excess air ratio of the gas fuel (the ratio of air in the mixture to the gas fuel) change. In the engine 2, abnormal combustion is likely to occur when the maximum temperature of the combustion chamber 12a becomes abnormally high, and when the excess air ratio of the gas fuel becomes low and the gas fuel becomes rich, the mixture is likely to ignite, so abnormal combustion is likely to occur.

[0062] For example, Figure 6The maximum temperature of the combustion chamber 12a measured when the gas fuel combustion ratio is changed under a certain engine load is indicated by a rectangular symbol, and the calculated excess air ratio of the gas fuel is indicated by a triangular symbol. According to the graph, in the stable operation area A1 where the gas fuel combustion ratio is relatively low (for example, less than 60%), the amount of liquid fuel added is large, so the temperature of the combustion chamber 12a becomes high due to the combustion of the liquid fuel, but the amount of gas fuel added is small and the gas fuel is thin, so there is a tendency that abnormal combustion does not occur. In addition, in the dangerous operation area A2 where the gas fuel combustion ratio is higher than the stable operation area A1 (for example, 60% to 90%), the gas fuel sometimes acts as a combustion-supporting material, so the temperature of the combustion chamber 12a rises sharply due to the combustion of the liquid fuel, and the amount of gas fuel added is large and the gas fuel is thick, so the mixed gas is easy to ignite, so there is a tendency that abnormal combustion is easy to occur. In addition, in the stable operation area A3 where the gas fuel mixing rate is higher than that in the dangerous operation area A2 (for example, more than 90%), the amount of gas fuel added is large and the gas fuel is thick, so the mixture is easy to ignite, but the amount of liquid fuel added is small, so the combustion of liquid fuel slows down and the temperature of the combustion chamber 12a does not become relatively high, so there is a tendency that abnormal combustion will not occur.

[0063] Therefore, when the control unit 9 switches the operating mode under a specified engine load, it refers to the danger zone map and, if it is determined that there is a danger zone of the gas fuel co-combustion ratio corresponding to the engine load, it can change the operating conditions in a manner that increases the maximum temperature of the combustion chamber 12a and / or the excess air ratio of the gas fuel, thereby canceling or alleviating the danger zone for limiting the gas fuel co-combustion ratio.

[0064] For example, the control unit 9 can control the internal temperature of the combustion chamber 12a by controlling the injection pressure, injection period, and injection number of the liquid fuel of the liquid fuel injection unit 17 as an operating condition. In addition, the control unit 9 can control the internal temperature of the combustion chamber 12a by controlling the injection pressure and injection period of the gas fuel of the gas fuel injection unit 16 as an operating condition. In addition, when the control unit 9 detects the rotation speed of the engine 2 through the rotation speed sensor 20 and calculates the engine output based on the rotation speed of the engine 2, it can control the internal temperature of the combustion chamber 12a and the air excess ratio of the gas fuel by feedback control of the engine output.

[0065] Furthermore, the control unit 9 may change at least one of the injection pressure of liquid fuel, the injection timing of liquid fuel, the number of injections of liquid fuel, the injection pressure of gas fuel, the injection timing of gas fuel, and the engine output, or may change a combination of two or more thereof.

[0066] In addition, the control unit 9 can control the supercharger 5, the intercooler 6, the first recirculation device 7, the second recirculation device 8, the exhaust bypass valve 4b, the intake valve 24, etc. as operating conditions, so as to reduce the intake air temperature of the combustion chamber 12a, increase the intake air pressure, increase the intake air volume, increase the specific heat of the intake air, etc., thereby controlling the internal temperature of the combustion chamber 12a and the excess air ratio of the gas fuel in a manner that increases.

[0067] Furthermore, the control unit 9 may change at least one of the intake air temperature of the combustion chamber 12a, the intake air pressure of the combustion chamber 12a, the intake air amount of the combustion chamber 12a, and the specific heat of the intake air of the combustion chamber 12a, or may change two or more of them in combination.

[0068] For example, the control unit 9 can reduce the temperature of the air supplied from the intake passage 3 and the intake port 22 to the combustion chamber 12a by controlling the flow rate of air passing through the intercooler 6, controlling the opening and closing period of the intake valve 24, or controlling the amount of cooling water and lubricating oil, thereby directly reducing the internal temperature of the combustion chamber 12a, slowing down the combustion in the combustion chamber 12a, and suppressing abnormal combustion.

[0069] In addition, the control unit 9 can increase the density of air supplied from the intake passage 3 and the intake port 22 to the combustion chamber 12a by controlling the exhaust bypass valve 4b and the compressor 5b of the supercharger 5, thereby reducing the ratio of gas fuel input to the combustion chamber 12a and suppressing abnormal combustion.

[0070] In addition, the control unit 9 can increase the amount of air supplied from the intake passage 3 and the intake port 22 to the combustion chamber 12a by controlling the flow rate of air passing through the intercooler 6, controlling the opening and closing period of the intake valve 24, controlling the exhaust bypass valve 4b, and controlling the compressor 5b of the supercharger 5, thereby reducing the ratio of gas fuel input into the combustion chamber 12a and suppressing abnormal combustion.

[0071] In addition, the control unit 9 can increase the specific heat of the air supplied from the intake passage 3 and the intake port 22 to the combustion chamber 12a by controlling the first recirculation device 7, the second recirculation device 8, or adjusting the humidity by means of water injection, for example, making the air contain more carbon dioxide or a large amount of water vapor, thereby reducing the internal temperature of the combustion chamber 12a during compression and suppressing abnormal combustion.

[0072] As described above, according to the first modified example, the engine device 1 can increase the maximum temperature of the combustion chamber 12a and / or the excess air ratio of the gas fuel by performing avoidance control to change at least one of the injection pressure of the liquid fuel, the injection period of the liquid fuel, the number of injections of the liquid fuel, the injection pressure of the gas fuel, the injection period of the gas fuel, and the engine output as operating conditions. In addition, the engine device 1 can increase the maximum temperature of the combustion chamber 12a and / or the excess air ratio of the gas fuel by performing avoidance control to change at least one of the intake air temperature of the combustion chamber 12a, the intake air pressure of the combustion chamber 12a, the intake air amount of the combustion chamber 12a, and the specific heat of the intake air of the combustion chamber 12a as operating conditions. Therefore, the dangerous area for limiting the gas fuel co-combustion ratio can be eliminated or alleviated, and the dangerous area in the dangerous area map can be reduced, so that even when the change of the gas fuel co-combustion ratio is limited in a manner not to enter the dangerous area, the range of changing the co-combustion ratio can be increased.

[0073] In addition, as a second modified example, when there is a danger zone between the current combustion rate and the target combustion rate when the gas fuel is changed, the control unit 9 may also perform avoidance control to change the combustion rate of the gas fuel in a manner of avoiding (skipping) the combustion rate within the range of the danger zone. At this time, in order to change the combustion rate of the gas fuel to avoid the danger zone, the control unit 9 may calculate the total input heat of the liquid fuel and the gas fuel at the current combustion rate and convert it into the input heat of the liquid fuel and the gas fuel at the target combustion rate.

[0074] For example, Figure 4 As shown, when the engine is operated at a predetermined engine load T1, when the control unit 9 switches from the diesel mode to the gas mode and gradually increases the combustion ratio of the gas fuel, the target combustion ratio is 100%, but the combustion ratio reaches the dangerous area at the combustion ratio R1 and the dangerous area continues to the combustion ratio R2. At this time, when the combustion ratio of the gas fuel reaches the combustion ratio R1 or approaches the combustion ratio R1, the control unit 9 sets the combustion ratio of the gas fuel to the combustion ratio R2 or more by skipping the dangerous area, thereby changing the combustion ratio to avoid the combustion ratio in the dangerous area.

[0075] In addition, when the control unit 9 switches from the gas mode to the diesel mode and gradually reduces the combustion ratio of the gas fuel, the target combustion ratio is 0%, but the combustion ratio reaches the dangerous area at the combustion ratio R2, and the dangerous area continues to the combustion ratio R1. At this time, when the combustion ratio of the gas fuel reaches the combustion ratio R2 or approaches the combustion ratio R2, the control unit 9 sets the combustion ratio of the gas fuel to less than the combustion ratio R1 by skipping the dangerous area, thereby changing the combustion ratio to avoid the combustion ratio in the dangerous area.

[0076] As described above, according to the second modified example, the engine device 1 performs avoidance control for changing the combustion ratio of the gas fuel by skipping the dangerous area, so that the combustion ratio of the gas fuel can be more reliably avoided from entering the range of the dangerous area, thereby being able to operate while avoiding abnormal combustion of the engine 2. In addition, the combustion ratio of the gas fuel can be changed to the target combustion ratio, so that the operation mode can be completely switched.

[0077] In addition, in the above-mentioned embodiment, the following example is described, that is, the engine device 1 is configured to switch to any one of the operating modes of the gas mode in which gas fuel is injected into the combustion chamber 12a for driving and the diesel mode in which liquid fuel is injected into the combustion chamber 12a for driving to operate, but the present invention is not limited to this example. In other examples, the engine device 1 may also be configured to operate in a mixed combustion mode in which both gas fuel and liquid fuel are injected into the combustion chamber 12a for driving as another operating mode.

[0078] The present invention can be modified appropriately within the scope of the gist or concept of the invention that can be read from the claims and the entire specification, and the engine device accompanying such modification is also included in the technical concept of the present invention.

[0079] [Notes on the invention]

[0080] The following is a summary of the invention extracted from the above-mentioned embodiment. In addition, each structure and each processing function described in the following notes can be selected and combined arbitrarily.

[0081] <Note 1>

[0082] An engine device is an engine device that is driven by injecting at least one of gas fuel and liquid fuel into a combustion chamber, characterized in that:

[0083] A dangerous area in which abnormal combustion can be predicted is set in advance for the mixed combustion ratio of the gas fuel contained in the fuel fed into the combustion chamber.

[0084] Avoid these danger zones when running the engine.

[0085] <Note 2>

[0086] The engine device according to note 1, characterized in that:

[0087] When the engine is operated while changing the co-firing ratio, avoidance control for avoiding the dangerous area is executed.

[0088] <Note 3>

[0089] The engine device according to note 1 or 2, characterized in that:

[0090] The above-mentioned dangerous region is set in advance with respect to the relationship between the engine load and the above-mentioned co-firing ratio.

[0091] <Note 4>

[0092] The engine device according to any one of appendixes 1 to 3, characterized in that:

[0093] As the avoidance control, the change of the co-firing ratio is restricted with respect to the dangerous area.

[0094] <Note 5>

[0095] The engine device according to any one of appendixes 1 to 4, characterized in that:

[0096] As the avoidance control, at least one of the injection pressure of the liquid fuel, the injection timing of the liquid fuel, the number of injections of the liquid fuel, the injection pressure of the gas fuel, the injection timing of the gas fuel, and the engine output is changed.

[0097] <Note 6>

[0098] The engine device according to any one of appendixes 1 to 5, characterized in that:

[0099] As the avoidance control, at least one of the intake air temperature of the combustion chamber, the intake air pressure of the combustion chamber, the intake air amount of the combustion chamber, and the specific heat of the intake air of the combustion chamber is changed.

[0100] <Note 7>

[0101] The engine device according to any one of appendixes 1 to 6, characterized in that:

[0102] As the avoidance control, when the dangerous region exists between the current combustion ratio and the target combustion ratio when the combustion ratio is changed, the combustion ratio is changed so as to avoid the combustion ratio in the dangerous region.

[0103] <Note 7>

[0104] The engine device according to any one of Appendix 1 to 7, wherein the gas fuel is hydrogen.

Claims

1. An engine device, which is an engine device driven by injecting at least one of gas fuel and liquid fuel into a combustion chamber, characterized in that: A dangerous region in which abnormal combustion can be predicted is set in advance for the mixed combustion ratio of the gas fuel contained in the fuel fed into the combustion chamber, Avoid the danger zone when running the engine.

2. The engine device according to claim 1, characterized in that: When the engine is operated while changing the co-firing ratio, avoidance control for avoiding the dangerous area is executed.

3. The engine device according to claim 1, characterized in that: The dangerous region is preset for the relationship between the engine load and the co-firing ratio.

4. The engine device according to claim 2, characterized in that: As the avoidance control, a change in the co-firing ratio is restricted with respect to the dangerous region.

5. The engine device according to claim 2, characterized in that: As the avoidance control, at least one of the injection pressure of the liquid fuel, the injection timing of the liquid fuel, the number of injections of the liquid fuel, the injection pressure of the gas fuel, the injection timing of the gas fuel, and the engine output is changed.

6. The engine device according to claim 2, characterized in that: As the avoidance control, at least one of the intake air temperature of the combustion chamber, the intake air pressure of the combustion chamber, the intake air amount of the combustion chamber, and the specific heat of the intake air of the combustion chamber is changed.

7. The engine device according to claim 2, characterized in that: As the avoidance control, when the dangerous region exists between the current burning ratio and the target burning ratio when the burning ratio is changed, the burning ratio is changed so as to avoid the burning ratio in the dangerous region.

8. The engine device according to claim 1, characterized in that: The gaseous fuel is hydrogen.

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