Engine device

Abstract

To provide an engine device that comprises an engine capable of performing idle operation and low load operation with a main fuel including a low GHG fuel, which has a less amount of greenhouse effect gas discharge, while suppressing an increase in product costs.SOLUTION: An engine device 1 comprises a multi-fuel engine 2 that is operated by burning a main fuel including a low GHG fuel, which has a less amount of greenhouse effect gas discharge than a petroleum-based fuel, and a hydrocarbon-based auxiliary fuel. The engine device comprises a main fuel injection unit 7a of a fuel injection unit 7, which injects the main fuel under electric control, an auxiliary fuel injection unit 7b of the fuel injection unit 7, which injects the auxiliary fuel under mechanical control, and a control unit 8 that electrically controls at least one of the injection volume, injection pressure, injection timing, and injection frequency of the main fuel by the main fuel injection unit 7a. The control unit 8 controls the rotation speed of the multi-fuel engine 2 at the time of idle operation.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an engine device having a multi-fuel engine that operates by burning a main fuel including a low-GHG fuel that emits less greenhouse gases than petroleum-based fuel, and a hydrocarbon-based secondary fuel. [Background technology]

[0002] Conventionally, there are engines that are compatible with multiple types of fuels, i.e., multi-fuel engines that supply multiple types of fuels. In order for a multi-fuel engine to be compatible with a main fuel containing a low-GHG (Green House Gas) fuel, such as ammonia or alcohol, which emits less greenhouse gases than petroleum-based fuels, it is necessary to combust even a main fuel that is difficult to ignite. To combust such a low-flammability main fuel, the engine system supplies a hydrocarbon-based secondary fuel, such as diesel, kerosene, or heavy oil, which is easy to ignite, to the multi-fuel engine in addition to the main fuel, thereby allowing the main fuel to be burned together with the secondary fuel.

[0003] For example, Patent Document 1 discloses a fuel injection device that injects fuel into cylinders of an internal combustion engine, and this fuel injection device has a main fuel system that injects fuel and a secondary fuel system that injects fuel at a pressure higher than the injection pressure of the main fuel system at the beginning of a fuel injection period. Alternatively, the fuel injection device has a main fuel system that injects fuel and a secondary fuel system that injects fuel at a pressure higher than the injection pressure of the main fuel system when injecting fuel simultaneously with the main fuel system.

[0004] According to Patent Document 1, the fuel injection device has a pressure detection means for detecting the pressure inside the cylinder of the internal combustion engine and a control means for changing the injection conditions of the secondary fuel based on the pressure detected by the pressure detection means. Alternatively, the fuel injection device has a control means for changing the injection conditions of the secondary fuel system according to the load conditions of the internal combustion engine, and performs injection of the secondary fuel system when the internal combustion engine is operating at a low load. Furthermore, according to Patent Document 1, the secondary fuel system has an accumulator for storing pressurized fuel, the internal combustion engine is a diesel engine, and the accumulator includes a common rail.

[0005] Furthermore, Patent Document 2 discloses a fuel injection device that injects fuel into the cylinders of an internal combustion engine, and this fuel injection device includes a main fuel injection means that injects main fuel, a secondary fuel injection means that injects secondary fuel, and a control means that injects the secondary fuel before injection of the main fuel and controls the secondary fuel injection means based on changes in initial combustion of the injection of the secondary fuel.

[0006] According to Patent Document 2, the internal combustion engine is a diesel engine, and the main fuel injection means injects the main fuel by mechanical control, and the secondary fuel injection means has an accumulator including a common rail that stores pressurized fuel, and injects the secondary fuel by electrical control. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-133391 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-036462 Summary of the Invention [Problem to be solved by the invention]

[0008] In the prior art disclosed in Patent Documents 1 and 2, a mechanically controlled injection device or a common rail system is used as a means for supplying a main fuel such as ammonia or alcohol to an engine, and a common rail system is used as a means for supplying a secondary fuel such as diesel, kerosene, or heavy oil to the engine. However, if a common rail system is used as both the main fuel supply means and the secondary fuel supply means, the product cost increases.

[0009] Furthermore, in the prior art disclosed in Patent Documents 1 and 2, a common rail system is used as the secondary fuel supply means, and to prevent increases in product costs, a mechanically controlled injection device is used as the main fuel supply means. However, compared to a common rail system, a mechanically controlled injection device has limitations in microinjection, low injection pressure during microinjection, and limited flexibility in changing the injection timing. Therefore, when the main fuel is supplied to the engine using a mechanically controlled injection device, the rotational stability of the engine decreases during idle operation, making it difficult to reduce the idle speed. For the same reason, when the main fuel is supplied to the engine using a mechanically controlled injection device, the rotational stability of the engine decreases during low-load operation.

[0010] To solve this problem, conventional engine devices use a common rail system to run the engine on secondary fuel when the engine is idling or operating at low load. However, this limits the use of low-GHG fuels such as ammonia or alcohol, making it impossible to promote the reduction of greenhouse gas emissions.

[0011] Furthermore, mechanically controlled injection devices generally have lower injection pressures than common rail systems, and there is less freedom in changing injection pressure, injection timing, and multi-stage injection. Therefore, when a mechanically controlled injection device is applied to a supply means for a main fuel that has low ignition properties and combustion speed, it is difficult to improve combustion performance such as atomizing the main fuel or strengthening penetration, and the limits on the use of the main fuel (for example, the amount used or the main fuel mixing ratio when mixing) are limited low.

[0012] The present invention aims to provide an engine device equipped with an engine that can be operated at idle or low load using a main fuel including a low-GHG fuel with low greenhouse gas emissions while suppressing increases in product costs. [Means for solving the problem]

[0013] In order to solve the above problems, the engine device of the present invention is an engine device that operates by burning a main fuel including a low-GHG fuel that emits less greenhouse gases than petroleum-based fuel and a hydrocarbon-based secondary fuel, and is equipped with a main fuel injection unit that injects the main fuel by electrical control, a secondary fuel injection unit that injects the secondary fuel by mechanical control, and a control device that electrically controls at least one of the injection amount, injection pressure, injection timing and number of injections of the main fuel by the main fuel injection unit, and is characterized in that the control device controls the rotational speed during engine idling. [Effects of the Invention]

[0014] According to the present invention, an engine device is provided that is equipped with an engine that can be operated in idle or at low load using a main fuel that includes a low-GHG fuel that emits less greenhouse gases, while suppressing increases in product costs. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram showing an engine device according to an embodiment of the present invention. [Figure 2] FIG. 10 is a schematic diagram showing an engine device according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] An engine system 1 according to an embodiment of the present invention will be described with reference to the drawings. As shown in Fig. 1, the engine system 1 includes a multi-fuel engine 2, an intake passage 3, an exhaust passage 4, a main fuel supply device 5, a secondary fuel supply device 6, a fuel injection unit 7, and a control device 8.

[0017] Particularly in this embodiment, the multi-fuel engine 2 is configured to operate by burning at least one fuel selected from a main fuel including low GHG (Green House Gas) fuels such as ammonia and alcohols (e.g., ethanol, butanol, and methanol) that emit fewer greenhouse gases than petroleum-based fuels, and a secondary fuel that is a hydrocarbon fuel such as diesel, kerosene, or heavy oil, in a combustion chamber 31a of each cylinder 31 formed by a cylinder 33 and a piston 34. In the engine device 1, a mixture of the main fuel and air is supplied to the combustion chamber 31a of each cylinder 31 of the multi-fuel engine 2. In the engine device 1, the supply of the main fuel and the secondary fuel is controlled by a control device 8.

[0018] The main fuel supply device 5 is configured as a common rail system including a main fuel tank 11, a main fuel pump 12, a common rail 13, a main fuel supply passage 14, and a main fuel supply valve 15. The multi-fuel engine 2 has a plurality of cylinders 31, and in Fig. 1, the main fuel supply passage 14 and the main fuel supply valve 15 for one cylinder 31 are shown, and the main fuel supply passage 14 and the main fuel supply valve 15 for the other cylinders 31 are not shown.

[0019] The main fuel tank 11 is filled with and stores the main fuel, which is a low-GHG fuel such as ammonia or alcohol that emits little greenhouse gases, from the outside, and is connected to a common rail 13 via a main fuel pump 12. The main fuel pump 12 pressurizes the main fuel stored in the main fuel tank 11 and supplies it to the common rail 13.

[0020] The common rail 13 is a main fuel accumulator that accumulates main fuel pressurized by the main fuel pump 12, and is provided in common to a plurality of cylinders 31 of the multi-fuel engine 2, and is connected to the fuel injection units 7 of each cylinder 31 via main fuel supply passages 14 provided for each cylinder 31. Each main fuel supply passage 14 is provided with a main fuel supply valve 15 that opens and closes the supply of main fuel from the common rail 13 to the fuel injection units 7. The opening and closing of the main fuel supply valve 15 is electrically controlled by the control device 8, and by opening the main fuel supply valve 15, the main fuel accumulated in the common rail 13 can be supplied to the fuel injection units 7 via the main fuel supply passage 14. In this way, the main fuel supply unit 5 is electrically controlled by the control device 8 to supply the main fuel to the fuel injection units 7 for injection.

[0021] The secondary fuel supply device 6 is a mechanically controlled device that includes a secondary fuel tank 16, a secondary fuel pump 17, an adjustment rack 18, an actuator 19, and a secondary fuel supply line 20. The multi-fuel engine 2 has multiple cylinders 31, and in Figure 1, the secondary fuel pump 17 and secondary fuel supply line 20 for one cylinder 31 are shown, and the secondary fuel pump 17 and secondary fuel supply line 20 for the other cylinders 31 are not shown.

[0022] The secondary fuel tank 16 is filled with and stores secondary fuel, which is a hydrocarbon fuel such as diesel, kerosene, or heavy oil, from the outside, and is connected to the secondary fuel pump 17 via a secondary fuel feed pump 16a. The secondary fuel pump 17 is provided for each cylinder 31 of the multi-fuel engine 2, supplies secondary fuel to the fuel injection unit 7, and is, for example, a secondary fuel accumulator that includes a cylindrical plunger barrel 21, a columnar plunger 22, and a secondary fuel valve 23, and accumulates pressurized secondary fuel.

[0023] The plunger barrel 21 is connected to the secondary fuel tank 16, and secondary fuel is supplied from the secondary fuel tank 16 to the internal space of the plunger barrel 21 by a secondary fuel feed pump 16a. The plunger 22 is disposed in the internal space of the plunger barrel 21 and is slidable along the direction in which the plunger 22 penetrates the internal space of the plunger barrel 21.

[0024] The secondary fuel supply device 6 also has a cam 24 that abuts against the plunger 22 at the other end of the plunger barrel 21 of each secondary fuel pump 17 in the penetration direction, a camshaft 25 that coaxially supports the cam 24 of each secondary fuel pump 17, and a plunger spring 26 that urges the plunger 22 of each secondary fuel pump 17 toward the cam 24.

[0025] As the cam 24 rotates together with the camshaft 25, the plunger 22 in contact with the cam 24 reciprocates relative to the plunger barrel 21. As the plunger 22 moves toward the other end in the penetration direction, secondary fuel pumped from the secondary fuel tank 16 by the secondary fuel feed pump 16a is introduced into the internal space of the plunger barrel 21, while as the plunger 22 moves toward one end in the penetration direction, the secondary fuel introduced into the internal space of the plunger barrel 21 is pressurized.

[0026] The secondary fuel valve 23 is provided at one end of the plunger barrel 21 in the penetration direction, and is connected to the secondary fuel supply passage 20. When the secondary fuel stored under pressure in the internal space of the plunger barrel 21 reaches or exceeds a predetermined pressure threshold, the secondary fuel valve 23 opens, the internal space of the plunger barrel 21 and the secondary fuel supply passage 20 communicate with each other, and secondary fuel is supplied from the secondary fuel pump 17 to the secondary fuel supply passage 20. For example, the secondary fuel valve 23 contains a biasing member, and when the pressure acting on the secondary fuel valve 23 reaches or exceeds a predetermined pressure threshold, the secondary fuel valve 23 opens against the biasing force of the biasing member.

[0027] The adjusting rack 18 is provided in common to multiple cylinders 31 of the multi-fuel engine 2 and adjusts the amount of secondary fuel supplied by each secondary fuel pump 17. For example, the secondary fuel supply device 6 has a pinion 27 that rotates integrally with the plunger 22 of each secondary fuel pump 17, and the adjusting rack 18 is arranged to mesh with each pinion 27. By linearly moving the adjusting rack 18, each pinion 27 rotates simultaneously, which in turn rotates the plungers 22 of each secondary fuel pump 17 simultaneously. The secondary fuel supply device 6 employs a known means that utilizes the rotation of the plungers 22 to adjust the amount of secondary fuel supplied by using the rotation of the plungers 22; in other words, it is possible to adjust the amount of secondary fuel supplied by using the movement of the adjusting rack 18.

[0028] The actuator 19 drives the adjusting rack 18 to move linearly, and may be configured using, for example, a solenoid or a motor. The actuator 19 operates in response to an electrical signal from the control device 8 to drive the adjusting rack 18.

[0029] In this way, the secondary fuel supply device 6 operates in a mechanically controlled manner, and supplies and injects secondary fuel pressurized by the secondary fuel pump 17 to the fuel injection unit 7 via the secondary fuel supply path 20. The actuator 19 operates in response to an electrical signal from the control device 8, but similar to conventional mechanically controlled fuel supply devices, it mechanically adjusts the amount of secondary fuel supplied by utilizing the movement of the adjusting rack 18, and in this specification, the configuration in which the amount of fuel supplied is adjusted by the adjusting rack 18 is referred to as mechanical control (type).

[0030] The fuel injection unit 7 supplies the main fuel and the secondary fuel separately to the combustion chamber 31a, and has a main fuel injection unit 7a that injects the main fuel into the combustion chamber 31a and a secondary fuel injection unit 7b that injects the secondary fuel into the combustion chamber 31a, and is configured, for example, as an integrated two-fuel injector. The fuel injection unit 7 is controlled by a control device 8 in terms of the injection timing, injection amount, injection pressure, injection frequency, etc. of the main fuel, as well as the injection amount of the secondary fuel.

[0031] The fuel injection unit 7 injects main fuel into the combustion chamber 31a when the piston 34 moves toward bottom dead center, and when the mixture of main fuel and air supplied into the combustion chamber 31a is compressed by the piston 34 moving toward top dead center, raising the temperature and pressure of the mixture, by injecting secondary fuel into the mixture in the combustion chamber 31a, igniting and burning the mixture. In other words, the fuel injection unit 7 (secondary fuel injection unit 7b) functions as an ignition device that ignites the mixture in the combustion chamber 31a.

[0032] The dual-fuel injector constituting the fuel injection unit 7 is configured, for example, to have a first valve chamber for supplying main fuel and a second valve chamber for supplying secondary fuel to one valve body, and is capable of supplying the main fuel and the secondary fuel separately by driving the valve bodies provided in each valve chamber to open and close. Alternatively, the dual-fuel injector is configured to have a first passage for supplying main fuel and a second passage for supplying secondary fuel to one valve body, and is equipped with nozzle holes communicating with each passage, and is configured to be able to supply the main fuel and the secondary fuel separately by switching the nozzle holes between the first and second passages.

[0033] The multi-fuel engine 2 is, for example, a four-stroke engine, and is configured with a cylinder block 30 including a plurality of cylinders 31 and a crankcase 32 (see FIG. 2). In FIG. 1, one cylinder 31 is shown, and the other cylinders 31 are not shown. As shown in FIG. 1, each cylinder 31 is configured with a cylinder 33, a piston 34, and a cylinder head 35.

[0034] The cylinder 33 is formed, for example, in a cylindrical shape within the cylinder block 30, and the piston 34 is slidably housed within the cylinder 33. The cylinder head 35 is attached to the upper side of the cylinder 33, and a combustion chamber 31a is formed inside the cylinder 33 and the cylinder head 35. The cylinder head 35 is provided with a fuel injection unit 7 that injects main fuel and secondary fuel into the combustion chamber 31a.

[0035] Each cylinder 33 of the multiple cylinders 31 is connected to a crankcase 32, and a crankshaft 37 is rotatably supported by the crankcase 32. A piston 34 of each cylinder 31 is connected to the crankshaft 37 via a connecting rod 38, and the reciprocating motion of the piston 34 is converted into the rotational motion of the crankshaft 37 via the connecting rod 38.

[0036] The cylinder head 35 has an intake port 39 and an exhaust port 40 that communicate with the combustion chamber 31a of the cylinder 33, and is equipped with an intake valve 41 and an exhaust valve 42 that open and close the intake port 39 and the exhaust port 40, respectively, to the combustion chamber 31a.

[0037] The intake port 39 is connected to the intake passage 3 and introduces air supplied from the intake passage 3 into the combustion chamber 31a, while the exhaust port 40 is connected to the exhaust passage 4 and discharges exhaust gas generated in the combustion chamber 31a into the exhaust passage 4. By opening the intake valve 41, a mixture of main fuel and air can be taken into the combustion chamber 31a via the intake port 39, while by opening the exhaust valve 42, exhaust gas generated in the combustion chamber 31a can be exhausted via the exhaust port 40.

[0038] The intake passage 3 is connected to a plurality of cylinders 31 of the multi-fuel engine 2 and supplies compressed and cooled air to each cylinder 31. A mixture of air supplied from the intake passage 3 and main fuel supplied from a main fuel supply device 5 is supplied from the intake passage 3 to the combustion chamber 31a of each cylinder 31. For example, the intake passage 3 is connected to the multi-fuel engine 2 via an intake manifold 43. The intake manifold 43 has branch passages 43a branching to the plurality of cylinders 31, and each branch passage 43a is connected to a respective intake port 39.

[0039] The exhaust passage 4 is connected to the multiple cylinders 31 of the multi-fuel engine 2, and passes and discharges exhaust gas generated in each cylinder 31. For example, the exhaust passage 4 is connected to the multi-fuel engine 2 via an exhaust manifold 44. The exhaust manifold 44 has branch passages 44a that branch off to the multiple cylinders 31, and each branch passage 44a is connected to a respective exhaust port 40. Note that the exhaust passage 4 may be equipped with a treatment device, such as a selective reduction catalyst or an ammonia adsorption catalyst, on the downstream side in the exhaust direction for treating the exhaust gas flowing through the exhaust passage 4.

[0040] The control device 8 is a computer such as an ECU (Engine Control Unit) that controls the operation of the multi-fuel engine 2, and is equipped with a CPU, ROM, RAM, etc., and is configured to control each part of the multi-fuel engine 2. The control device 8 may store various programs for controlling the multi-fuel engine 2, and control the multi-fuel engine 2 by reading and executing the programs.

[0041] Particularly in this embodiment, the control device 8 electrically controls at least one of the injection amount, injection pressure, injection timing, and number of injections of the main fuel by the main fuel injection unit 7a of the fuel injection unit 7, and also controls the rotation speed during idle operation or low load operation of the multi-fuel engine 2. That is, when the multi-fuel engine 2 is operated at idle or low load, the control device 8 operates the multi-fuel engine 2 at a relatively low rotation speed, and the control device 8 controls at least one of the injection amount, injection pressure, injection timing, and number of injections of the main fuel to correspond to the low rotation speed of the multi-fuel engine 2, thereby injecting a small amount of main fuel. At this time, the control device 8 electrically controls each main fuel supply valve 15 corresponding to each cylinder 31, thereby controlling at least one of the injection amount, injection pressure, injection timing, and number of injections of the main fuel so that the main fuel injection unit 7a injects a small amount of main fuel.

[0042] For example, when the multi-fuel engine 2 is idling or operating at a low load, the control device 8 controls the injection of the main fuel by the main fuel injector 7a (injection amount, injection pressure, injection timing, number of injections, etc.) so that a small amount of main fuel is injected and the calorific value of the main fuel is 50% or more of the total calorific value of the main fuel and secondary fuel. Note that the control device 8 may also control so that the calorific value of the main fuel is 50% or more of the total calorific value of the main fuel and secondary fuel during a predetermined period of time during idling or operating at a low load.

[0043] Furthermore, for example, when the multi-fuel engine 2 is idling or operating at a low load, the control device 8 controls the injection of the main fuel by the main fuel injection unit 7a (injection amount, injection pressure, injection timing, number of injections, etc.) so that the injection pressure of the main fuel by the main fuel injection unit 7a is higher than the injection pressure of the secondary fuel by the secondary fuel injection unit 7b, and in this case, it is preferable that the control device 8 controls so that the maximum value of the injection pressure of the main fuel is higher than the maximum value of the injection pressure of the secondary fuel in one cycle of the multi-fuel engine 2.

[0044] Furthermore, for example, when the multi-fuel engine 2 is idling or operating at a low load, the control device 8 controls the injection of the main fuel by the main fuel injector 7a so that the main fuel is injected multiple times into each cylinder 31 in one cycle of the multi-fuel engine 2. In this case, the control device 8 may perform control so that the main fuel is injected multiple times during the compression stroke of each cylinder 31, and may be as the piston 34 moves toward top dead center, when the piston 34 has reached top dead center, or immediately after the piston 34 has reached top dead center.

[0045] Furthermore, the control device 8 may control the amount of secondary fuel injected by the secondary fuel injection unit 7 b. For example, the control device 8 controls the amount of secondary fuel injected by the secondary fuel injection unit 7 b by sending an electric signal to the actuator 19 of the secondary fuel supply device 6 to control the movement of the adjustment rack 18.

[0046] As described above, according to the present invention, engine system 1, which operates by burning a main fuel containing a low-GHG fuel that emits fewer greenhouse gases than petroleum-based fuel and a hydrocarbon-based secondary fuel, includes main fuel injection unit 7a of fuel injection unit 7 that injects the main fuel by electrical control, secondary fuel injection unit 7b of fuel injection unit 7 that injects the secondary fuel by mechanical control, and control device 8 that electrically controls at least one of the injection amount, injection pressure, injection timing, and number of injections of the main fuel by main fuel injection unit 7a, and control device 8 controls the rotation speed during idle operation of multi-fuel engine 2. For example, the main fuel contains ammonia or alcohol as a low-GHG fuel.

[0047] As a result, the engine system 1 of the present invention uses a common rail system as the main fuel injection means and a mechanically controlled device as the secondary fuel injection means, thereby suppressing cost increases. Furthermore, by using a common rail system to inject flame-retardant main fuels such as ammonia and alcohol, it is possible to perform minute injections, atomize the fuel through high-pressure injection, and inject the fuel at the optimal injection timing. This enables stable idle operation and low-load operation using the main fuel, and also enables lower idle speeds. Furthermore, there are no restrictions on the use of low-GHG fuels, such as ammonia and alcohol, during idle operation and low-load operation, which can promote a reduction in greenhouse gas emissions.

[0048] Furthermore, in the engine system 1 of the present invention, the control device 8 controls the injection of the main fuel so that the calorific value of the main fuel is 50% or more of the total calorific value of the main fuel and secondary fuel when the multi-fuel engine 2 is idling.

[0049] This allows the engine device 1 to use a large amount of main fuel during idle operation, thereby reducing consumption of hydrocarbon-based secondary fuel and increasing consumption of the main fuel, which is a low-GHG fuel, thereby contributing to the conservation of the global environment.

[0050] Furthermore, in the engine system 1 of the present invention, the control device 8 controls the injection pressure of the main fuel to be higher than the injection pressure of the secondary fuel.

[0051] As a result, in the engine device 1, the flame-retardant main fuel is injected at a higher pressure than the secondary fuel using a common rail system, thereby making it possible to atomize the fuel more finely and strengthening penetration, thereby improving the flame-retardant properties of the main fuel.

[0052] Furthermore, in the engine device 1 of the present invention, the control device 8 controls the injection of the main fuel so that the main fuel is injected multiple times into each cylinder 31 during one cycle of the multi-fuel engine 2.

[0053] As a result, in the engine device 1, the main fuel is injected and burned multiple times, which makes it possible to improve the exhaust gas properties and fuel economy.

[0054] In the engine device 1 of the present invention, the control device 8 controls the injection amount of secondary fuel. For example, the engine device 1 of the present invention includes a secondary fuel pump 17 that supplies secondary fuel to the secondary fuel injection unit 7b, an adjusting rack 18 that adjusts the amount of secondary fuel supplied by the secondary fuel pump 17, and an actuator 19 that drives the adjusting rack 18. The actuator 19 operates in response to an electric signal from the control device 8.

[0055] As a result, the engine system 1 places the injection amount of secondary fuel under the control of the control device 8 for the common rail system, making it possible to omit a control device for a mechanically controlled device and also to avoid dual control of injection control of multiple fuels. In particular, in a mechanically controlled device that is the secondary fuel injection means, the injection amount of secondary fuel is determined by the operation of an adjusting rack 18 relative to a secondary fuel pump 17, but by controlling the actuator 19 that drives the adjusting rack 18 with the control device 8 for the common rail system, the injection amount of secondary fuel can be placed under the control of the control device 8 for the common rail system.

[0056] In the above embodiment, the fuel injection unit 7 is configured as an integrated dual-fuel injector having a main fuel injection unit 7a that injects main fuel and a secondary fuel injection unit 7b that injects secondary fuel. However, the present invention is not limited to this example. For example, in another embodiment, as shown in FIG. 2 , the fuel injection unit 7 may be configured such that the main fuel injection unit 7a that injects main fuel and the secondary fuel injection unit 7b that injects secondary fuel are separate injectors. In this case, the main fuel injection unit 7a that injects main fuel may be positioned to directly supply the main fuel to the combustion chamber 31a by injecting the main fuel directly into the combustion chamber 31a. Alternatively, the main fuel injection unit 7a may be positioned to indirectly supply the main fuel to the combustion chamber 31a by injecting the main fuel into the intake passage 3, the branch flow path 43a, or the intake port 39.

[0057] Furthermore, the present invention can be modified as appropriate within the scope that does not contradict the gist or idea of ​​the invention that can be read from the claims and the entire specification, and engine devices that involve such modifications are also included in the technical idea of ​​the present invention.

[0058] [Appendix to the invention] The following is a summary of the invention extracted from the above-described embodiment. Note that the configurations and processing functions described in the following supplementary notes can be selected and combined as desired.

[0059] <Appendix 1> An engine device that operates by burning a main fuel including a low-GHG fuel that emits less greenhouse gases than petroleum-based fuel and a hydrocarbon-based secondary fuel, a main fuel injection unit that injects the main fuel under electrical control; a secondary fuel injection unit that injects the secondary fuel by mechanical control; a control device that electrically controls at least one of an injection amount, an injection pressure, an injection timing, and an injection number of times of the main fuel by the main fuel injection unit, The engine device is characterized in that the control device controls the rotation speed of the engine during idling operation.

[0060] <Appendix 2> 2. The engine device according to claim 1, wherein the control device controls the injection of the main fuel so that the heat generation amount of the main fuel is 50% or more of the total heat generation amount of the main fuel and the secondary fuel during idling operation of the engine.

[0061] <Appendix 3> 3. The engine device according to claim 1, wherein the control device controls the injection of the main fuel so that the injection pressure of the main fuel is higher than the injection pressure of the secondary fuel.

[0062] <Appendix 4> 4. The engine device according to any one of claims 1 to 3, wherein the control device controls the main fuel to be injected multiple times into each cylinder during one cycle of the engine.

[0063] <Appendix 5> 5. The engine device according to any one of claims 1 to 4, wherein the control device controls the injection amount of the secondary fuel.

[0064] <Appendix 6> a secondary fuel pump that supplies the secondary fuel to the secondary fuel injection portion; an adjustment rack for adjusting the amount of the secondary fuel supplied by the secondary fuel pump; an actuator that drives the adjustment rack, 6. The engine device according to claim 5, wherein the actuator is operated by an electrical signal from the control device.

[0065] <Appendix 7> 7. The engine device according to any one of claims 1 to 6, wherein the main fuel contains ammonia or alcohol as the low GHG fuel. [Explanation of symbols]

[0066] 1 Engine equipment 2 Multi-fuel engine 3 Intake passage 4 Exhaust passage 5 Main fuel supply system 6 Auxiliary fuel supply device 7 Fuel injection part 7a Main fuel injection section 7b Auxiliary fuel injection section 8 Control Device 11 Main fuel tank 12 Main fuel pump 13 Common rail 14 Main fuel supply path 15 Main fuel supply valve 16. Secondary fuel tank 17 Auxiliary fuel pump 18 Adjustable Rack 19 Actuators 20 Secondary fuel supply path 30 Cylinder block 31 cylinders 31a Combustion chamber 32 Crankcase 33 cylinders 34 Piston 35 cylinder head 37 crankshaft 38 Connecting rod 39 Intake port 40 Exhaust port 41 Intake valve 42 Exhaust valve 43 Intake manifold 43a Branch channel 44 Exhaust manifold 44a Branch channel

Claims

1. An engine device that operates by burning a main fuel including a low GHG fuel that emits less greenhouse gases than petroleum-based fuel and a hydrocarbon-based secondary fuel, a main fuel injection unit that injects the main fuel under electrical control; a secondary fuel injection unit that injects the secondary fuel by mechanical control; a control device that electrically controls at least one of an injection amount, an injection pressure, an injection timing, and an injection number of times of the main fuel injected by the main fuel injection unit, The engine device is characterized in that the control device controls the rotation speed of the engine during idling operation.

2. 2. The engine device according to claim 1, wherein the control device controls the injection of the main fuel so that a heat generation amount of the main fuel is 50% or more of a total heat generation amount of the main fuel and the secondary fuel during idling operation of the engine.

3. 2. The engine device according to claim 1, wherein the control device controls the injection pressure of the main fuel so that the injection pressure of the secondary fuel is higher than the injection pressure of the secondary fuel.

4. 2. The engine device according to claim 1, wherein the control device controls the main fuel to be injected into each cylinder a plurality of times during one cycle of the engine.

5. 2. The engine device according to claim 1, wherein the control device controls the injection amount of the secondary fuel.

6. a secondary fuel pump that supplies the secondary fuel to the secondary fuel injection portion; an adjustment rack for adjusting the amount of the secondary fuel supplied by the secondary fuel pump; an actuator that drives the adjustment rack, 6. The engine device according to claim 5, wherein the actuator is operated by an electric signal from the control device.

7. 2. The engine apparatus according to claim 1, wherein the main fuel contains ammonia or alcohol as the low GHG fuel.

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