Dual fuel injection system, injection unit pump, engine, and injection method

Abstract

The invention provides a dual-fuel injection system, an injection method, an engine and an electronic unit pump. The injection system comprises a dual-fuel electronic unit pump which comprises a first pressure buildup assembly, a second pressure buildup assembly and a cam driving assembly, the first pressure buildup assembly comprises a first pressure buildup plunger and a first matching part matched with the first pressure buildup plunger, and the second pressure buildup assembly comprises a second matching part matched with the second pressure buildup plunger. The second pressure buildup assembly comprises a second pressure buildup plunger and a second matching part matched with the second pressure buildup plunger. The cam driving assembly comprises a driving shaft, a first cam and a second cam, the first cam and the second cam are arranged on the same driving shaft, the first cam and the second cam can be driven by the driving shaft, the first cam is matched with the first pressure buildup plunger, the second cam is matched with the second pressure buildup plunger, and the second cam is matched with the second pressure buildup plunger. The included angle between the first cam and the second cam can change along with the working condition of the dual-fuel injection system.

Description

Technical Field

[0001] The invention relates to a dual fuel injection system, an injection unit pump, an engine and an injection method. Background Art

[0002] To reduce pollution and carbon emissions from engines, alternative fuels such as low-carbon fuel methanol and zero-carbon fuel ammonia are gradually being used in engines. As a core component of alternative fuels, the fuel injection system is the key to the reliable operation of alternative fuel engines.

[0003] A dual fuel injection system generally requires injection of a conventional fuel such as diesel, and an alternative fuel such as methanol or ammonia.

[0004] In some existing technologies, the existing dual-fuel injection system uses an additional independent fuel injection system compared to the single fuel injection system of the diesel engine, that is, a diesel injection system and another independent alternative fuel injection system. The diesel is pressurized by a high-pressure pump, and the alternative fuel is pressurized by another high-pressure pump, so that the two fuels are pressurized and injected into the engine cylinder according to the required injection time. The disadvantage of this is that the additional injection system will greatly increase the cost of the entire machine.

[0005] In order to solve the problem of cost, some existing technologies use a solution of using diesel and alternative fuel to build pressure by sharing a pressure building module. For example, a cam can be used to drive a first pressure building plunger of diesel and a second pressure building plunger of alternative fuel arranged in the same plane with a fixed angle to build pressure for the two fuels, and then inject them into the engine cylinder through two injectors at a fixed time difference. However, the inventors found that although this solution of sharing a pressure building module reduces costs, it is difficult to adjust the injection timing in real time according to the engine operating conditions because the fuel injection timing of diesel and alternative fuel is fixed, which is not conducive to the fuel economy and emission performance of the engine.

[0006] Therefore, there is a need in the art for a dual fuel injection system, an injection unit pump, an engine and an injection method, so as to ensure the fuel economy and emission performance of the engine while reducing the cost of the entire machine. Summary of the invention

[0007] An object of the present invention is to provide a dual fuel injection system.

[0008] An object of the present invention is to provide a dual fuel injection method.

[0009] An object of the present invention is to provide a dual fuel engine.

[0010] An object of the present invention is to provide a dual fuel injection unit pump.

[0011] According to one aspect of the present application, a dual-fuel injection system includes a fuel injector connected to a high-cetane number fuel high-pressure oil circuit and an alternative fuel high-pressure oil circuit; a dual-fuel electronically controlled single pump, including a first pressure-building component, a second pressure-building component and a cam drive component, wherein the first pressure-building component includes a first pressure-building plunger and a first pair of parts that cooperate with the first pressure-building plunger, and the second pressure-building component includes a second pressure-building plunger and a second pair of parts that cooperate with the second pressure-building plunger; the cam drive component includes a drive shaft, and a first cam and a second cam that are arranged on the same drive shaft, wherein the first cam and the second cam can be driven by the drive shaft, and the first cam and the first pressure-building plunger are connected to each other. The second cam cooperates with the second pressure-building plunger, and the angle between the first cam and the second cam can change with the working condition of the dual fuel injection system; the fuel low-pressure oil circuit includes a high-cetane number fuel low-pressure oil circuit and an alternative fuel low-pressure oil circuit; the fuel flow path provided by the dual fuel injection system includes: high-cetane number fuel enters the first pressure-building component through the high-cetane number fuel low-pressure oil circuit to build pressure, and is output to the fuel injector through the high-cetane number fuel high-pressure oil circuit after building pressure from the first pressure-building component; the alternative fuel enters the second pressure-building component through the alternative fuel low-pressure oil circuit to build pressure, and is output to the fuel injector through the alternative fuel high-pressure oil circuit after building pressure from the second pressure-building component.

[0012] In the technical solution of the embodiment introduced above, in a dual-fuel injection system, the injection of two fuels shares the same pressure building module, thereby overcoming the problem of increased cost of an additional independent fuel injection system. On this basis, through a structure in which the angle between the first cam and the second cam is variable, that is, a cam timing variable structure, the injection interval of the two fuels can be adjusted according to the working conditions, thereby achieving balanced fuel consumption, emission and other comprehensive performance of the engine; in addition, the use of a single pump also improves the reliability of the injection system.

[0013] In one or more embodiments of the dual fuel injection system, the fuel injector is an integrated dual fuel injector of high cetane fuel and alternative fuel; or the fuel injector includes a high cetane fuel injector and an alternative fuel injector, and the high cetane fuel injector and the alternative fuel injector are separate injectors.

[0014] In one or more embodiments of the dual fuel injection system, the second cam includes a fixed part and a movable part, the second cam is connected to the drive shaft via the fixed part, and the movable part is arranged around the fixed part at the periphery of the fixed part, so that the movable part provides the profile of the second cam; the movable part can rotate relative to the fixed part in the circumferential direction, so that the angle between the second cam and the first cam is variable.

[0015] In one or more embodiments of the dual fuel injection system, the fixed part includes: a fixed part body connected to the drive shaft, and a fixed part blade portion extending radially outward from the body; the movable part has an inner chamber, the inner chamber accommodates the fixed part, the inner chamber includes an inner chamber body corresponding to the fixed part body, and an inner chamber blade portion corresponding to the fixed part blade portion; the space between the fixed part blade portion and the inner chamber blade portion constitutes a first chamber, a second chamber and an intermediate channel connecting the first chamber and the second chamber, the first chamber has an input end for receiving a pressure medium; the first chamber and the second chamber are respectively connected to a first cam channel and a second cam channel, one end of the first cam channel and the second cam channel is located in the first chamber and the second chamber, and the other end is located at the periphery of the movable part, serving as an output end of the pressure medium for outputting the pressure medium; the fuel injection system also includes a valve element, the valve element is arranged in the pressure medium flow path output by the first cam channel and the second cam channel.

[0016] In one or more embodiments of the dual fuel injection system, the fixed portion blade portion is connected to the inner chamber blade portion via an elastic member provided in the second chamber, while the first chamber is not connected with the elastic member.

[0017] In one or more embodiments of the dual fuel injection system, the valve element is disposed in a flow path of the pressure medium output from the first cam channel.

[0018] In one or more embodiments of the dual fuel injection system, the valve element comprises a solenoid valve, and the solenoid valve is electrically connected to an electronic control unit.

[0019] In one or more embodiments of the dual fuel injection system, the drive shaft includes a hollow portion and a channel extending from the hollow portion to an outer wall of the drive shaft, and the channel corresponds to an input end of the pressure medium of the first chamber.

[0020] In one or more embodiments of the dual fuel injection system, the pressure medium is lubricating oil, and the first cam hole and the second cam hole output the lubricating oil to the oil pan.

[0021] According to a second aspect of the present application, a dual fuel injection method adopts the dual fuel injection system as described in the first aspect, and the injection method includes: when the engine starts, the angle between the first cam and the second cam is a default angle; when the engine stops working, the angle between the first cam and the second cam is a default angle; when the engine is working or changes operating conditions, the angle between the first cam and the second cam changes with the operating conditions of the dual fuel injection system; the fuel injection system injects alternative fuel and high cetane number fuel, or only injects high cetane number fuel.

[0022] A dual-fuel engine according to the third aspect of the present application comprises a dual-fuel injection system as described in the first aspect, and a cylinder, through which an alternative fuel and a high-cetane number fuel are directly injected into the cylinder, or only the high-cetane number fuel is directly injected into the cylinder.

[0023] According to the fourth aspect of the present application, a dual-fuel injection single pump includes: a first pressure-building component, the first pressure-building component includes a first pressure-building plunger, and a first mating part that cooperates with the first pressure-building plunger; a second pressure-building component, the second pressure-building component includes a second pressure-building plunger, and a second mating part that cooperates with the second pressure-building plunger; a cam drive component, the cam drive component includes a drive shaft, and a first cam and a second cam arranged on the same drive shaft, the first cam and the second cam can be driven by the drive shaft; the first cam cooperates with the first pressure-building plunger, the second cam cooperates with the second pressure-building plunger, and the angle between the first cam and the second cam is a variable angle. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and other features, properties and advantages of the present invention will become more apparent through the following description in conjunction with the accompanying drawings and embodiments. In the accompanying drawings, the same reference numerals always represent the same features. It should be noted that these drawings are only for examples and are not drawn according to the conditions of equal scale, and should not be used as a limitation on the actual scope of protection required by the present invention.

[0025] in:

[0026] Figure 1 Schematic diagram of the structure of a dual fuel injection system according to an embodiment.

[0027] Figure 2A , Figure 2B They are schematic diagrams of an electronically controlled unit pump structure of a dual fuel injection system according to an embodiment at different viewing angles.

[0028] Figure 3 The figure is a schematic diagram of a first cam and a second cam of a dual fuel injection system according to an embodiment.

[0029] Figure 4 FIG. 1 is a schematic diagram of the flow path of the pressure medium of a dual fuel injection system according to an embodiment.

[0030] Figure 5 A schematic block diagram of an engine according to an embodiment.

[0031] Reference numerals:

[0032] 1000-Engine

[0033] 100-Dual fuel injection system

[0034] 101-High cetane fuel

[0035] 102-Alternative Fuels

[0036] 1- Fuel Injector

[0037] 2-Dual fuel electronically controlled unit pump

[0038] 21-First pressure building component

[0039] 211-First pressure building plunger

[0040] 212-First Pair

[0041] 22-Second pressure building component

[0042] 221-Second pressure building plunger

[0043] 222-Second Pair

[0044] 23-Cam drive assembly

[0045] 230-Drive shaft

[0046] 2301-Hollow part

[0047] 2302-Hole

[0048] 231-First Cam

[0049] 232-Second Cam

[0050] 2321-Fixed part

[0051] 23211-Fixed part main body

[0052] 23212-Fixed blade part

[0053] 23213-Oil hole

[0054] 2322-Moving parts

[0055] 23220-Inner Chamber

[0056] 23221-Inner chamber body

[0057] 23222-Inner chamber blade

[0058] 23231-First cam channel

[0059] 23232-Second cam channel

[0060] 2401-First Chamber

[0061] 2402-Second Chamber

[0062] 2403-Middle Channel

[0063] 2404-Elastic parts

[0064] 3-Fuel low pressure oil circuit

[0065] 31-High cetane fuel low pressure oil circuit

[0066] 311, 321-Low pressure pump

[0067] 312, 322-Low pressure pipe

[0068] 313-High Cetane Fuel Tank

[0069] 323-Alternative Fuel Tank

[0070] 32-Alternative fuel low pressure oil circuit

[0071] 41-High cetane fuel high pressure oil circuit

[0072] 42-Alternative fuel high pressure oil circuit

[0073] 5-Valve element

[0074] 50-Solenoid valve

[0075] 51, 52-Oil return pipe

[0076] 6-Electronic Control Unit

[0077] 7-Oil sump

[0078] 71, 72-lubricating oil pipe

[0079] 73-Output oil pipe

[0080] 200-cylinder. DETAILED DESCRIPTION

[0081] Reference will now be made in detail to various embodiments of the present invention, examples of which are shown in the accompanying drawings and described below. Although the present invention will be described in conjunction with the exemplary embodiments, it should be appreciated that this specification is not intended to limit the present invention to those exemplary embodiments. On the contrary, the present invention is intended to cover not only these exemplary embodiments, but also various alternative forms, modifications, equivalent forms and other embodiments that may be included within the spirit and scope of the present invention as defined by the appended claims.

[0082] In the following description, the orientation or positional relationship indicated by "inside", "outside", "upper", "lower", "top", "bottom" or other orientation terms is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0083] At the same time, the present application uses specific words to describe the embodiments of the present application. For example, "some embodiments" means a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "some embodiments" mentioned twice or multiple times in different locations in this specification do not necessarily refer to the same embodiment. In addition, some features, structures or characteristics of some embodiments of the present application can be appropriately combined.

[0084] Although the dual-fuel injection system, injection method, single pump, and engine disclosed in the embodiments of the present application are suitable for marine engines to achieve reliable dual-fuel operation, they are not limited to this. For example, they can be applicable to other application scenarios, such as heavy vehicles and railway trains. As long as the engine needs to adopt a dual-fuel injection solution, the dual-fuel injection system, method, and engine disclosed in the present application can be applied.

[0085] In the following description, "high cetane number fuel" may also be referred to as traditional fuel, taking diesel as an example; and "alternative fuel" may be referred to as methanol as an example.

[0086] like Figure 5 As shown, in some embodiments, the dual-fuel engine 1000 includes a dual-fuel injection system 100 described in detail in the following embodiments, and a cylinder 200, through which the alternative fuel and the high-cetane number fuel are directly injected into the cylinder, or only the high-cetane number fuel is directly injected into the cylinder, so as to reduce the cost and achieve improvements in the fuel economy and emission performance of the engine.

[0087] For dual fuel injection systems, there are generally a first mode or a second mode. In the first mode, the alternative fuel is mainly burned, which can also be called the alternative fuel mode. In this mode, diesel is used as the ignition. In the second mode, diesel fuel is essentially the only fuel burned, which can also be called the traditional fuel mode or the pure diesel mode. In this mode, the dual fuel system only injects diesel, that is, only injects high cetane number fuel.

[0088] Specifically, refer to Figures 1 to 3 As shown, in some embodiments, the dual fuel injection system 100 may include a fuel injector 1 , a dual fuel electronically controlled unit pump 2 , and a fuel low pressure oil circuit 3 .

[0089] like Figure 1 As shown, the fuel injector 1 is connected to the high-cetane fuel high-pressure oil circuit 41 and the alternative fuel high-pressure oil circuit 42. In some embodiments, the fuel injector 1 is an integrated dual-fuel injector of the high-cetane fuel and the alternative fuel; but it is not limited to this. For example, the fuel injector 1 can also include a high-cetane fuel injector and an alternative fuel injector, and the high-cetane fuel injector and the alternative fuel injector are separate injectors.

[0090] Continue to refer Figures 1 to 3 As shown, the dual-fuel electronically controlled unit pump 2 includes a first pressure-building component 21, a second pressure-building component 22, and a cam drive component 23. The first pressure-building component 21 includes a first pressure-building plunger 211 and a first pair 212 that cooperates with the first pressure-building plunger 211. The second pressure-building component 22 includes a second pressure-building plunger 221 and a second pair 222 that cooperates with the second pressure-building plunger 221. The cam drive component 23 includes a drive shaft 230, and a first cam 231 and a second cam 232 that are arranged on the same drive shaft. The first cam 231 and the second cam 232 can be driven by the drive shaft. The first cam 231 cooperates with the first pressure-building plunger 211, and the second cam 232 cooperates with the second pressure-building plunger 221. The angle between the first cam 231 and the second cam 232 can change with the working conditions of the dual-fuel injection system. The angle between the first cam and the second cam here means the phase difference of the cam timing between the two.

[0091] The fuel low-pressure oil passage 3 includes a high-cetane number fuel low-pressure oil passage 31 and an alternative fuel low-pressure oil passage 32 .

[0092] refer to Figure 1As shown, the fuel flow path provided by the dual fuel injection system 100 includes: the high cetane number fuel enters the first pressure building component 21 through the high cetane number fuel low-pressure oil circuit 31 to build pressure, and is output to the fuel injector 1 through the high cetane number fuel high-pressure oil circuit 41 after being pressure-built from the first pressure building component 21; the alternative fuel enters the second pressure building component 22 through the alternative fuel low-pressure oil circuit 32 to build pressure, and is output to the fuel injector 1 through the alternative fuel high-pressure oil circuit 42 after being pressure-built from the second pressure building component 22.

[0093] Specifically, the high cetane number fuel 101 can be built up with low pressure through the low pressure pump 311, and transported to the pressure building inlet of the high cetane number fuel 101 of the dual-fuel electronically controlled unit pump 2 through the low pressure pipe 312, and the alternative fuel 102 can be built up with low pressure through the low pressure pump 321, and transported to the pressure building inlet of the alternative fuel 102 of the dual-fuel electronically controlled unit pump 2 through the low pressure pipe 322. The first pressure building plunger 211 and the first mating part 212 of the first pressure building assembly 21 are independent from the second pressure building assembly 22 including the second pressure building plunger 221 and the second mating part 222, and are not connected to each other. The operation of the engine drives the drive shaft 230 to rotate, and the drive shaft 230 rotates with the first cam 231 and the second cam 232. The first cam 231 and the second cam 232 regularly push the first pressure-building plunger 211 and the second pressure-building plunger 221 respectively. The first pressure-building plunger 211 and the second pressure-building plunger 221 move up and down, respectively squeezing the high-cetane number fuel 101 and the alternative fuel 102 in the closed space of the first mating part 212 and the second mating part 222, thereby completing the establishment of the high-cetane number fuel 101 and the alternative fuel 102 from low pressure to high pressure in turn; the high-cetane number fuel 101 and the alternative fuel 102 after establishing high pressure are respectively passed through the high-cetane number fuel in turn. The high-pressure oil circuit 41 of the raw material and the high-pressure oil circuit 42 of the alternative fuel are transported to the two inlets of the dual-fuel injector 1. The integrated dual-fuel injector 1 includes two independent fuel injection channels. The high-cetane number fuel 101 and the alternative fuel 102 are independently and sequentially injected into the cylinders of the dual-fuel engine; the excess high-cetane number fuel 101 and the alternative fuel 102 are respectively returned to the high-cetane number fuel tank 313 and the alternative fuel tank 323 through the two return oil holes of the dual-fuel injector 1 via the return oil pipe 51 and the return oil pipe 52; the above process completes the separate injection of the two fuels of one cylinder. For a multi-cylinder dual-fuel engine, the injection of other cylinders is the same as above and will not be repeated.

[0094] like Figure 2A , Figure 2B as well as Figure 3 As shown, the first cam 231 and the second cam 232 are installed on the same drive shaft 230 and integrated in the single pump; there is an angle a between the first cam 231 and the second cam 232 .

[0095] The key components of the dual-fuel electronically controlled unit pump 2 include a first cam 231 and a second cam 232, and there is an angle a between the two. The angle a can realize the separate injection of the high cetane number fuel 101 and the alternative fuel 102. Generally speaking, the fuel injected first is the common high cetane number fuel 101, that is, diesel, and the fuel injected later is the alternative fuel that is difficult to compress or ignite, such as methanol; the injection interval of the two fuels during the operation of the dual-fuel engine has a great influence on the fuel economy and emission performance of the engine.

[0096] In some embodiments, reference Figure 2A , Figure 2B as well as Figure 3 As shown, the second cam 232 includes a fixed part 2321 and a movable part 2322. The second cam 232 is connected to the drive shaft 230 through the fixed part 2321. The movable part 2322 is arranged around the fixed part 2321 on the periphery of the fixed part 2321, so that the movable part 2322 provides the profile of the second cam 232; the movable part 2322 can rotate relative to the fixed part 2321 in the circumferential direction, so that the angle between the second cam 232 and the first cam 231 is variable, that is, during operation, it can be changed from the default angle a to adapt to the injection timing of dual fuel under different working conditions.

[0097] Continue to refer Figure 3 As shown, in some embodiments, the structure of the fixed part can be that the fixed part 2321 includes: a fixed part main body 23211 connected to the drive shaft 230, and a fixed part blade portion 23212 extending radially outward from the main body; the movable part 2322 has an inner chamber 23220, the inner chamber 23220 accommodates the fixed part 2321, and the inner chamber 23220 includes an inner chamber main body 23221 corresponding to the fixed part main body 23211, and an inner chamber blade portion 23222 corresponding to the fixed part blade portion 23212. The space between the fixed part blade portion 23212 and the inner chamber blade portion 23222 constitutes the first chamber 2401, the second chamber 2402 and the intermediate channel 2403 connecting the first chamber 2401 and the second chamber 2402. The first chamber 2401 has an input end for receiving the pressure medium; the first chamber 2401 and the second chamber 2402 are respectively connected to the first cam channel 23231 and the second cam channel 23232. One end of the first cam channel 23231 and the second cam channel 23232 are located in the first chamber 2401 and the second chamber 2402, and the other end is located at the periphery of the movable part 2322, serving as the output end of the pressure medium for outputting the pressure medium. The fuel injection system 100 also includes a valve element 5, which is arranged in the pressure medium flow path output by the first cam channel 23231 and the second cam channel 23232. Continue to refer to Figure 3As shown, the structure of controlling the movement of the movable part 2322 by the valve may also include that the fixed part blade portion 23212 is connected to the inner chamber blade portion 23222 through the elastic member 2404 provided in the second chamber 2402, while the first chamber 2401 is not connected with the elastic member. In some embodiments, the valve element 5 is provided in the flow path of the pressure medium output by the first cam channel 23231. This can facilitate the angle between the first cam and the second cam to maintain the default value a when the engine is started or stopped. In addition, continue to refer to Figure 3 As shown, the valve element 5 includes an electromagnetic control valve 50, and the electromagnetic control valve 50 is electrically connected to the electronic control unit 6. In this way, the pressure adjustment control of the pressure medium can be easily performed.

[0098] In some embodiments, the pressure medium is lubricating oil, the drive shaft 230 includes a hollow portion 2301, and a channel 2302 extending from the hollow portion 2301 to the outer wall of the drive shaft, and the channel 2302 corresponds to the input end of the pressure medium of the first chamber 2401. Correspondingly, in some embodiments, the first cam channel 23231 and the second cam channel 23232 output lubricating oil to the oil pan 7. The structure of providing the pressure medium in this way is compact, and the structure of the drive shaft is cleverly utilized. However, it can be understood that the pressure medium can also be other fluids, for example, the high cetane number fuel 101 and the alternative fuel 102 mentioned above can be used, and this is not a limitation.

[0099] Continue to refer Figure 3 as well as Figure 4 When lubricating oil is used as the pressure medium, the pressure medium flow path for adjusting the angle between cams in the fuel injection system 100 can be that the drive shaft 230 is a hollow structure, the hollow part 2301 is filled with lubricating oil with pressure, and at the same time, 5 holes 2302 extending from the hollow part 2301 to the outer wall of the drive shaft are evenly distributed in the radial direction of the drive camshaft 5. The number of holes 2302 is determined according to the number of engine cylinders. For example, in a 6-cylinder engine, corresponding to 6 dual-fuel high-pressure pumps, the holes 2302 need to be arranged at 6 positions in the axial direction of the drive camshaft. The fixed part 2321 is provided with an oil hole 23213, and the fixed part 2321 is coaxially installed on the drive shaft 230 according to the oil hole 23213 and the hole 2302. The movable part 2322 is connected to the fixed part blade part 23212 of the fixed part 2321 through an elastic member 2404, such as an angle adjustment spring, and an oil chamber, and is coaxially installed on the drive shaft 230.

[0100] In the oil chamber of the movable part 2322, the fixed part blade portion 23212 divides the oil chamber into a first chamber 2401 and a second chamber 2402. The first chamber 2401 and the second chamber 2402 are respectively connected to a first cam hole 23231 and a second cam hole 23232. The two cam holes are respectively connected to the lubricating oil pipe 71 and the lubricating oil pipe 72. The lubricating oil pipe 71 is connected to a valve element 5 for oil chamber pressure, such as a solenoid valve 50. The solenoid valve 50 is electrically connected to an electronic control unit 6 to receive a control signal. An output oil pipe 73 of the solenoid valve 50 is connected to an oil pan 7. The lubricating oil pipe 72 is fluidically connected to a second chamber 2402 on a spring side of a second chamber oil chamber having an elastic member 2404, and is connected to a second cam channel 23232 to introduce lubricating oil into the oil pan 7. It can be understood that the figure only reflects the connection of one oil chamber, and the actual structure can be designed with multiple oil chambers according to requirements. The lubricating oil pipes of all oil chambers are ultimately gathered to the same valve element 5, and the relevant lubricating oil pipes in the figure are no longer reflected in the figure.

[0101] refer to Figure 4 As shown, the principle of changing the angle between the first cam and the second cam as the working condition of the dual fuel injection system changes by using the pressure medium of lubricating oil as an example can be that when the engine is working or the working condition is changed, the lubricating oil pump builds up pressure on the lubricating oil, and the pressurized lubricating oil enters the drive shaft 230 through the main oil channel, and the pressure lubricating oil in the drive shaft 230 enters the first chamber 2401 of the oil cavity through the hole 2302 and the oil hole 23213 located in the fixed part 2321, and the pressure lubricating oil in the first chamber 2401 enters the solenoid valve 50 through the first cam hole 23231 and the lubricating oil pipe 71. The electronic control unit 6 sends a pressure adjustment signal to the solenoid valve 50 according to the working condition and pressure adjustment MAP solidified in the engine calibration stage, and the solenoid valve 50 controls the valve opening size according to the received signal, and discharges the lubricating oil in the first chamber 2401 through the lubricating oil pipe 73 into the oil pan 7, thereby adjusting the lubricating oil pressure in the first chamber 2401. Under the combined pressure of the lubricating oil pressure in the first chamber 2401 and the elastic member 2404, the movable part 2322 rotates along the axial direction of the drive shaft 230 to achieve a change in the angle, thereby achieving a change in the pressure building time of the alternative fuel 102, and finally achieving a change in the time interval between the high cetane number fuel 101 and the alternative fuel 102 entering the cylinder, thereby achieving the economy and emission of the dual-fuel engine under different working conditions. Due to the matching clearance, during the operation of the engine, the pressurized lubricating oil in the first chamber 2401 will continuously penetrate into the second chamber 2402 through the intermediate channel 2403, and the penetrated lubricating oil will pass through the second cam channel 23232 and the lubricating oil pipe 72 corresponding to the second chamber 2402, and return to the oil pan 7 without pressure, that is, the flow direction of the lubricating oil in the variable injection timing cam is shown in the figure. Figure 4 shown.

[0102] When the engine starts, the lubricating oil pressure in the drive shaft 230 is low, and the lubricating oil pressure in the first chamber 2401 of the movable part 2322 is insufficient to resist the preload pressure of the angle adjustment spring in the second chamber 2402. The movable part 2322 remains in the initial position under the pressure of the angle adjustment spring, and starts at the default angle a, thereby ensuring smooth starting and starting performance.

[0103] When the engine stops working, there is no lubricating oil in the drive shaft 230, and the lubricating oil pressure in the first chamber 2401 of the movable part 2322 is zero. The movable part 2322 returns to the initial position under the preload pressure of the angle adjustment spring, thereby resetting the angle to the default angle a, preparing for the next start.

[0104] As described above, the present application further provides a dual-fuel injection method, using the dual-fuel injection system 100 described in the above embodiment, the injection method includes:

[0105] When the engine is started, the angle between the first cam 231 and the second cam 232 is a default angle;

[0106] When the engine stops working, the angle between the first cam 231 and the second cam 232 is a default angle;

[0107] When the engine is operating or the operating conditions change, the angle between the first cam 231 and the second cam 232 changes with the operating conditions of the dual fuel injection system;

[0108] The fuel injection system 100 injects the alternative fuel as well as the high cetane fuel, or injects only the high cetane fuel.

[0109] In addition, the present application also provides a dual-fuel electronically controlled single pump 2, including: a first pressure building component 21, the first pressure building component 21 includes a first pressure building plunger 211, and a first pair 212 that cooperates with the first pressure building plunger 211; a second pressure building component 22, the second pressure building component 22 includes a second pressure building plunger 221, and a second pair 222 that cooperates with the second pressure building plunger 221; a cam driving component 23, the cam driving component 23 includes a driving shaft 230, and a first cam 231 and a second cam 232 arranged on the same driving shaft, the first cam 231 and the second cam 232 can be driven by the driving shaft 230; the first cam 231 cooperates with the first pressure building plunger 211, the second cam 232 cooperates with the second pressure building plunger 221, and the angle between the first cam 231 and the second cam 232 is a variable angle.

[0110] In summary, the beneficial effects of the dual-fuel injection system, injection method and engine introduced above include but are not limited to the following: in the dual-fuel injection system, the injection of the two fuels shares the same pressure building module, thereby overcoming the problem of increased cost of the solution due to the addition of an additional independent fuel injection system; on this basis, through the structure with a variable angle between the first cam and the second cam, i.e., a variable cam timing structure, the injection interval of the two fuels can be adjusted according to the operating conditions, thereby achieving balanced fuel consumption, emissions and other comprehensive performance of the engine; in addition, the use of a single pump also improves the reliability of the injection system.

[0111] Although the present invention is disclosed as above in terms of preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, any modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the scope of protection defined by the claims of the present invention.

Claims

1. A dual fuel injection system (100), characterized in that: include: A fuel injector (1) connected to a high-cetane fuel high-pressure oil circuit (41) and an alternative fuel high-pressure oil circuit (42); A dual-fuel electronically controlled unit pump (2) comprises a first pressure-building component (21), a second pressure-building component (22) and a cam drive component (23), wherein the first pressure-building component (21) comprises a first pressure-building plunger (211) and a first mating component (212) cooperating with the first pressure-building plunger (211), the second pressure-building component (22) comprises a second pressure-building plunger (221) and a second mating component (222) cooperating with the second pressure-building plunger (221); the cam drive component (23) comprises A drive shaft (230), and a first cam (231) and a second cam (232) arranged on the same drive shaft, wherein the first cam (231) and the second cam (232) can be driven by the drive shaft, the first cam (231) cooperates with the first pressure-building plunger (211), and the second cam (232) cooperates with the second pressure-building plunger (221), and the angle between the first cam (231) and the second cam (232) can change with the working condition of the dual-fuel injection system; A fuel low-pressure oil circuit (3), comprising a high-cetane number fuel low-pressure oil circuit (31) and an alternative fuel low-pressure oil circuit (32); The fuel flow path provided by the dual fuel injection system (100) comprises: the high cetane number fuel enters the first pressure building component (21) through the high cetane number fuel low pressure oil circuit (31) to build pressure, and after the pressure is built up from the first pressure building component (21), it is output to the fuel injector (1) through the high cetane number fuel high pressure oil circuit (41); The alternative fuel enters the second pressure building component (22) through the alternative fuel low-pressure oil circuit (32) to build up pressure, and after building up pressure from the second pressure building component (22), is output to the fuel injector (1) through the alternative fuel high-pressure oil circuit (42).

2. The fuel injection system (100) according to claim 1, characterized in that The fuel injector (1) is an integrated dual fuel injector for high cetane number fuel and alternative fuel; or the fuel injector (1) includes a high cetane number fuel injector and an alternative fuel injector, wherein the high cetane number fuel injector and the alternative fuel injector are separate injectors.

3. The fuel injection system (100) according to claim 1, characterized in that The second cam (232) comprises a fixed part (2321) and a movable part (2322); the second cam (232) is connected to the drive shaft (230) via the fixed part (2321); the movable part (2322) is arranged around the fixed part (2321) on the periphery of the fixed part (2321), so that the movable part (2322) provides a profile of the second cam (232); the movable part (2322) can rotate relative to the fixed part (2321) in the circumferential direction, so that the angle between the second cam (232) and the first cam (231) is variable.

4. The fuel injection system (100) according to claim 3, characterized in that The fixed part (2321) comprises: a fixed part main body (23211) connected to the driving shaft (230), and a fixed part blade part (23212) extending radially outward from the main body; the movable part (2322) has an inner chamber (23220), the inner chamber (23220) accommodates the fixed part (2321), and the inner chamber (23220) comprises an inner chamber main body (23221) corresponding to the fixed part main body (23211), and an inner chamber blade part (23222) corresponding to the fixed part blade part (23212); The space between the fixed part blade portion (23212) and the inner chamber blade portion (23222) constitutes a first chamber (2401), a second chamber (2402) and an intermediate channel (2403) connecting the first chamber (2401) and the second chamber (2402); the first chamber (2401) has an input end for receiving a pressure medium; the first chamber (2401) and the second chamber (2402) are respectively connected to a first cam channel (23231) and a second cam channel (23232); one end of the first cam channel (23231) and the second cam channel (23232) are located in the first chamber (2401) and the second chamber (2402), and the other end is located at the periphery of the movable part (2322), serving as an output end of the pressure medium, and used for outputting the pressure medium; The fuel injection system (100) further comprises a valve element (5), wherein the valve element (5) is arranged in a pressure medium flow path output by the first cam channel (23231) and the second cam channel (23232).

5. The fuel injection system (100) according to claim 4, characterized in that The fixed part blade portion (23212) and the inner chamber blade portion (23222) are connected via an elastic member (2404) provided in the second chamber (2402), while the first chamber (2401) is not connected with an elastic member.

6. The fuel injection system (100) according to claim 5, characterized in that The valve element (5) is arranged in the flow path of the pressure medium output by the first cam channel (23231).

7. The fuel injection system (100) according to claim 4, characterized in that The valve element (5) comprises a solenoid valve (50), and the solenoid valve (50) is electrically connected to an electronic control unit (6).

8. The fuel injection system (100) according to claim 4, characterized in that The drive shaft (230) includes a hollow portion (2301) and a channel (2302) extending from the hollow portion (2301) to the outer wall of the drive shaft, and the channel (2302) corresponds to the input end of the pressure medium of the first chamber (2401).

9. The fuel injection system (100) according to claim 4, characterized in that The pressure medium is lubricating oil, and the first cam hole (23231) and the second cam hole (23232) output the lubricating oil to the oil pan (7).

10. A dual fuel injection method, characterized in that: A fuel injection system (100) as claimed in any one of claims 1 to 9 is used; the injection method comprises: When the engine is started, the angle between the first cam (231) and the second cam (232) is a default angle; When the engine stops working, the angle between the first cam (231) and the second cam (232) is a default angle; When the engine is operating or the operating condition changes, the angle between the first cam (231) and the second cam (232) changes with the operating condition of the dual fuel injection system; The fuel injection system (100) injects alternative fuel and high cetane fuel, or injects only high cetane fuel.

11. A dual fuel engine (1000), characterized in that: It comprises a dual fuel injection system (100) as claimed in any one of claims 1 to 9, and a cylinder (200), through which the dual fuel injection system (100) is used to directly inject an alternative fuel and a high cetane number fuel into the cylinder, or only the high cetane number fuel is directly injected into the cylinder.

12. A dual-fuel electronically controlled unit pump (2), characterized in that: include: A first pressure-building component (21), the first pressure-building component (21) comprising a first pressure-building plunger (211), and a first mating member (212) cooperating with the first pressure-building plunger (211); A second pressure-building component (22), the second pressure-building component (22) comprising a second pressure-building plunger (221), and a second coupling member (222) cooperating with the second pressure-building plunger (221); A cam driving assembly (23), the cam driving assembly (23) comprising a driving shaft (230), and a first cam (231) and a second cam (232) arranged on the same driving shaft, wherein the first cam (231) and the second cam (232) can be driven by the driving shaft (230); The first cam (231) cooperates with the first pressure-building plunger (211), and the second cam (232) cooperates with the second pressure-building plunger (221), and the angle between the first cam (231) and the second cam (232) is a variable angle.

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