Fuel injection system, injection method and engine

Abstract

The invention provides a heavy oil injection system, an engine and an injection method. The heavy oil injection system comprises a heavy oil system which comprises a heavy oil supply pump, a heavy oil common rail pipe, a heavy oil fuel injector and a first pipeline connected with the heavy oil supply pump, the heavy oil common rail pipe and the heavy oil fuel injector. The pilot medium system comprises a pilot medium pump, a pilot medium common rail pipe and a second pipeline connecting the pilot medium pump, the pilot medium common rail pipe and the heavy oil fuel injector, and the pilot medium system provides pilot media for the heavy oil fuel injector to conduct pilot control.

Description

Technical Field

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

[0002] Fuel costs are one of the largest operating expenses for engines, typically accounting for 20% to 50%. Oil prices significantly impact shipping companies' profits, so using heavy fuel oil as engine fuel offers cost savings. Heavy fuel oil, with its low cost, abundant reserves, excellent performance, and high safety, has become the fuel of choice for many ocean-going vessels.

[0003] Currently, there are two main technical approaches for heavy oil fuel injection systems. One is the common rail heavy oil fuel injection system, which allows for precise pressure control of the heavy oil common rail pipe. However, the inventors have discovered that the high temperature, strong corrosiveness, and high viscosity of heavy oil fuel place high demands on the heavy oil common rail injector and the oil pump solenoid valve. Existing heavy oil common rail injectors typically use solenoid valves to control the servo oil pressure buildup and release, thereby driving the movement of a control piston. The control piston further drives the injector pilot valve to open and close, thereby achieving heavy oil injection control. The presence of the control piston increases the mass and inertia of the injector's moving parts, slowing the injector's dynamic response. Furthermore, the control piston's hydraulic amplification mechanism results in a large and complex injector. The heavy oil common rail pump requires internal cooling oil channels to cool the proportional solenoid valve, resulting in a complex structure and poor reliability. These factors have hindered the further practical application of common rail heavy oil injection systems. Another technical route is to use an electronically controlled single pump or a mechanical single pump to pressurize the heavy oil and drive the mechanical nozzle to spray. In this way, the oil supply pressure changes with the engine speed, and it is difficult to achieve precise control of the injection pressure.

[0004] Therefore, the art needs a fuel injection system, an injection method, and an engine to solve at least one of the above technical problems. Summary of the Invention

[0005] An object of the present invention is to provide a fuel injection system.

[0006] Another object of the present invention is to provide a spraying method.

[0007] Another object of the present invention is to provide an engine.

[0008] According to one aspect of the present application, a fuel injection system includes: a heavy oil system, including a heavy oil supply pump, a heavy oil common rail, and a heavy oil fuel injector, and a first pipeline connecting the heavy oil supply pump, the heavy oil common rail, and the heavy oil fuel injector; and a pilot medium system, including a pilot medium pump, a pilot medium common rail, and a second pipeline connecting the pilot medium pump, the pilot medium common rail, and the heavy oil fuel injector. The pilot medium system provides pilot medium to the heavy oil fuel injector for pilot control.

[0009] The technical solution introduced above adopts a dual common rail structure with independent heavy oil common rail and pilot light oil common rail to achieve precise control of heavy oil injection pressure and pilot light oil pressure, thereby improving injection stability; the injector eliminates the traditional hydraulic amplification mechanism and directly controls heavy oil injection through pilot light oil pressure buildup and pressure relief, thereby improving injection response, and has a simple and reliable structure.

[0010] In one or more embodiments of the fuel injection system, the fuel oil circuit provided by the heavy oil injection system includes:

[0011] The heavy oil is pressurized by the heavy oil supply pump and enters the heavy oil common rail through the first pipeline, maintains a first pressure in the heavy oil common rail, and enters the heavy oil oil circuit of the heavy oil fuel injector through the first pipeline to provide the heavy oil as fuel injection;

[0012] The pilot medium is pressurized by the pilot medium pump and enters the pilot medium common rail through the second pipeline. A second pressure is maintained in the pilot medium common rail. The pilot medium at the second pressure enters the pilot medium flow path of the heavy oil fuel injector through the second pipeline, providing pilot control of fuel injection by the heavy oil fuel injector.

[0013] In one or more embodiments of the fuel injection system, the heavy oil system further includes a first pressure limiting valve, a first flow limiting valve, and a first rail pressure sensor; the pilot medium system further includes a second pressure limiting valve and a second rail pressure sensor.

[0014] In one or more embodiments of the fuel injection system, the heavy oil system further includes a flushing valve, which is integrated with the first pressure limiting valve and is connected to the pilot medium system.

[0015] In one or more embodiments of the fuel injection system, the injection system further includes a control unit, and the control unit is electrically connected to the heavy oil system and the pilot medium system respectively.

[0016] In one or more embodiments of the fuel injection system, the heavy oil supply pump is a rack-type mechanical pump, the control unit is electrically connected to the heavy oil supply pump, and controls the rack of the rack-type mechanical pump so that the heavy oil maintains a first pressure in the heavy oil common rail pipe; the control unit is electrically connected to the pilot medium pump so that the pilot medium maintains a second pressure in the pilot medium common rail pipe.

[0017] In one or more embodiments of the fuel injection system, the heavy oil fuel injector is a leak-free structure, and the first pressure is greater than the second pressure.

[0018] In one or more embodiments of the fuel injection system, the heavy oil fuel injector has a leakage structure, and the heavy oil injection system further includes a waste oil circuit, which is connected to the heavy oil fuel injector and receives a mixture of leaked heavy oil and pilot medium discharged from the heavy oil fuel injector.

[0019] In one or more embodiments of the fuel injection system, the pilot medium is light oil.

[0020] A fuel injection method according to a second aspect of the present application is used in the heavy oil injection system as described in the first aspect.

[0021] An engine according to a third aspect of the present application includes the heavy oil injection system as described in the first aspect, and the cylinders of the engine are correspondingly provided with the heavy oil fuel injectors. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] 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 illustration and are not drawn to scale. They should not be used to limit the actual scope of protection claimed by the present invention. Among them:

[0023] Figure 1 FIG. 1 is a schematic diagram of a fuel injection system according to a first embodiment.

[0024] Figure 2 This is a schematic diagram of a pilot medium flow path of a heavy oil fuel injector of the fuel injection system of the first embodiment.

[0025] Figure 3 Schematic diagram of a heavy oil oil passage and a pilot medium flow passage of a heavy oil fuel injector of the fuel injection system of the first embodiment.

[0026] Figure 4 This is a partial structural diagram of the position corresponding to the middle block of the heavy oil fuel injector of the fuel injection system of the first embodiment.

[0027] Figure 5 This is a partial structural diagram of the corresponding positions of the needle valve assembly of the heavy oil fuel injector of the fuel injection system of the first embodiment.

[0028] Figure 6 FIG. 1 is a schematic diagram of a fuel injection system according to a second embodiment.

[0029] Figure 7 This is a schematic diagram of the partial structure corresponding to the middle block of the heavy oil fuel injector of the fuel injection system of the second embodiment.

[0030] Figure 8 FIG. 4 is a flow chart of a fuel injection method according to an embodiment.

[0031] Reference numerals:

[0032] 1000-Engine

[0033] 100-Fuel injection system

[0034] 1-Heavy oil system

[0035] 11-Heavy oil supply pump

[0036] 12-Heavy oil common rail pipe

[0037] 13-Heavy oil fuel injector

[0038] 14-First pipeline

[0039] 15-First pressure limiting valve

[0040] 16-First flow limiting valve

[0041] 17-First rail pressure sensor

[0042] 18-Flush valve

[0043] 2-Pilot medium system

[0044] 21-Pilot medium pump

[0045] 22-Pilot medium common rail pipe

[0046] 23-Second pipeline

[0047] 24-Second pressure limiting valve

[0048] 25-Second rail pressure sensor

[0049] 3-Control Unit

[0050] 4-Waste oil pipe

[0051] 200-Heavy Oil Storage Department

[0052] 300-Light oil storage department

[0053] 400-Waste oil storage department. DETAILED DESCRIPTION

[0054] 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 description is not intended to limit the invention to those exemplary embodiments. On the contrary, the present invention is intended to cover not only those exemplary embodiments, but also various alternatives, modifications, equivalents, and other embodiments that may be included within the spirit and scope of the invention as defined by the appended claims.

[0055] In the subsequent description, the orientations or positional relationships indicated by “inside,” “outside,” “up,” “down,” “top,” “bottom,” or other orientation terms are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or component referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the present invention.

[0056] At the same time, this application uses specific terms to describe the embodiments of this application. For example, "some embodiments" refers to a feature, structure, or characteristic related to at least one embodiment of this application. Therefore, it should be emphasized and noted that "some embodiments" mentioned twice or multiple times in different places in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics of some embodiments of this application may be appropriately combined.

[0057] This application uses flowcharts to illustrate the operations performed by the systems and methods according to the embodiments of the present application. It should be understood that the preceding or following operations are not necessarily performed in exact order. Other operations may also be added to these processes, or one or more operations may be removed from these processes.

[0058] Currently, there are two main technical approaches for heavy oil fuel injection systems. One is the common rail heavy oil fuel injection system, which allows for precise pressure control of the heavy oil common rail pipe. However, the inventors have discovered that the high temperature, strong corrosiveness, and high viscosity of heavy oil fuel place high demands on the heavy oil common rail injector and the oil pump solenoid valve. Existing heavy oil common rail injectors typically use solenoid valves to control the servo oil pressure buildup and release, thereby driving the movement of a control piston. The control piston further drives the injector pilot valve to open and close, thereby achieving heavy oil injection control. The presence of the control piston increases the mass and inertia of the injector's moving parts, slowing the injector's dynamic response. Furthermore, the control piston's hydraulic amplification mechanism results in a large and complex injector. The heavy oil common rail pump requires internal cooling oil channels to cool the proportional solenoid valve, resulting in a complex structure and poor reliability. These factors have hindered the further practical application of common rail heavy oil injection systems. Another technical route is to use an electronically controlled single pump or a mechanical single pump to pressurize the heavy oil and drive the mechanical nozzle to spray. In this way, the oil supply pressure changes with the engine speed, and it is difficult to achieve precise control of the injection pressure.

[0059] Based on the above, the inventors have conducted in-depth research and designed a fuel injection system. By adopting a dual common rail structure with independent heavy oil common rail and pilot light oil common rail, precise control of heavy oil injection pressure and pilot light oil pressure can be achieved, thereby improving injection stability. The injector eliminates the traditional hydraulic amplification mechanism and directly controls the heavy oil injection through the pressure buildup and pressure relief of the pilot light oil, thereby improving the injection response. The system has a simple and reliable structure.

[0060] Although the injection system, injection method, and engine disclosed in the embodiments of the present application are suitable for marine engines, they are not limited thereto. For example, they can be applied to other application scenarios, such as heavy vehicles, railway trains, stationary power generation, etc. As long as the engine needs to use heavy oil as a fuel injection solution, the fuel injector, injection system, injection method, and engine disclosed in the present application can be applied.

[0061] In the following descriptions, the concepts of "heavy fuel oil" and "light fuel oil" are used with marine fuel as an example. Light fuel oil is primarily used for main engine maneuvering, such as entering and leaving ports, navigating narrow waterways, and sailing in inclement weather, as well as for auxiliary engines, boiler starting and shutting down, etc. Heavy fuel oil generally includes two types: marine diesel oil (MDO), which is generally suitable for medium-speed diesel engines and for use when ships enter special waters. Marine gas oil or gasoline (MGO), which has a lower viscosity than MDO and is generally suitable for high-speed diesel engines, used when entering special waters or ports, and for oil changes in main and auxiliary engines (such as during dry docking). Both MGO and MDO are light fuel oils. Heavy oil refers to the blended intermediate fuel oil (INTERMEDIATE FUEL OIL, IFO, or Heavy Fuel Oil, HFO). As a kind of finished oil, heavy oil is the heavier residual product separated from crude oil after gasoline, kerosene and diesel are produced during the oil processing process. It is mainly made from petroleum cracking residue oil and straight-run residue oil. It is characterized by high viscosity and contains a lot of non-hydrocarbon compounds, gums and asphaltene. Therefore, heavy oil is sometimes also called marine residual fuel oil.

[0062] In the following descriptions, light oil is used as an example of a pilot medium. Light oil can be used as both a pilot medium and a cleaning medium, and in some cases, as a fuel. However, other pilot media can also be used, such as lubricating oil or hydraulic oil.

[0063] refer to Figure 1 、 Figure 6As shown, engine 1000 includes a fuel injection system 100, which will be described in detail below. Heavy oil fuel injectors 13 are provided corresponding to the engine cylinders. This allows the engine to operate in both a heavy oil mode, using heavy oil as fuel, and a light oil mode, using light oil as fuel. Specifically, the engine includes fuel injection system 100, a heavy oil reservoir 200, and a light oil reservoir 300. The heavy oil fuel injectors 13 of fuel injection system 100 are capable of communicating with either the heavy oil reservoir 200 or the light oil reservoir 300. Specifically, when the engine is in the heavy oil mode, the heavy oil circuit of the heavy oil fuel injector 13 connects to the heavy oil reservoir 200 but not to the light oil reservoir 300. Similarly, when the engine is in the light oil mode, the heavy oil circuit of the fuel injector 100 connects to the light oil reservoir 300 but not to the heavy oil reservoir 200. However, the engine and injection system described in the embodiments offer the advantage of high economic efficiency and generally operate in heavy oil mode, often operating in this mode. Therefore, the fuel supply circuit is referred to as the heavy oil circuit. The pilot medium flow path of the heavy oil fuel injector 13 serves only as a pilot medium flow path, not as a fuel flow path. Therefore, it can only communicate with the light oil reservoir 300, not the heavy oil reservoir 200. It should be understood that the above example uses light oil as the pilot medium. If the pilot medium is lubricating oil or hydraulic oil rather than light oil, which cannot serve as fuel, the lubricating oil reservoir can only communicate with the pilot medium flow path of the heavy oil fuel injector 13, not the heavy oil circuit of the heavy oil fuel injector 13.

[0064] The heavy oil injection system 100 includes a heavy oil system 1 and a pilot medium system 2. The heavy oil system 1 includes a heavy oil supply pump 11, a heavy oil common rail 12, and heavy oil fuel injectors 13, as well as a first pipeline 14 connecting the heavy oil supply pump 11, the heavy oil common rail 12, and the heavy oil fuel injectors 13. The pilot medium system 2 includes a pilot medium pump 21, a pilot medium common rail 22, and a second pipeline 23 connecting the pilot medium pump 21, the pilot medium common rail 22, and the heavy oil fuel injectors 13. The pilot medium system 2 provides pilot medium to the heavy oil fuel injectors 13 for pilot control.

[0065] The fuel oil circuit provided by the heavy oil injection system 100 includes:

[0066] The heavy oil is pressurized by the heavy oil supply pump 11 and enters the heavy oil common rail 12 through the first pipeline 14. The heavy oil common rail 12 maintains a first pressure, and the heavy oil at the first pressure enters the heavy oil oil circuit of the heavy oil fuel injector 13 through the first pipeline 14, providing the heavy oil as fuel injection;

[0067] After being pressurized by the pilot medium pump 21, the pilot medium enters the pilot medium common rail pipe 22 through the second pipeline 23. The second pressure is maintained in the pilot medium common rail pipe 22, and the pilot medium at the second pressure enters the pilot medium flow path of the heavy oil fuel injector 13 through the second pipeline 23, providing pilot control of the fuel injection of the heavy oil fuel injector 13.

[0068] The beneficial effect of such a structure is that by adopting a dual common rail structure with independent heavy oil common rail and pilot light oil common rail, precise control of heavy oil injection pressure and pilot light oil pressure can be achieved, thereby improving injection stability; the injector eliminates the traditional hydraulic amplification mechanism, and realizes direct control of heavy oil injection through pilot light oil pressure building and pressure relief, thereby improving injection response, and the structure is simple and reliable.

[0069] Continue to refer Figure 1 as well as Figure 6 As shown, the heavy oil system 1 may further include a first pressure limiting valve 15, a first flow limiting valve 16, and a first rail pressure sensor 17; the pilot medium system 2 may further include a second pressure limiting valve 24 and a second rail pressure sensor 25. This makes it easier to precisely control the pressures of the heavy oil and pilot medium.

[0070] In some embodiments, the heavy oil system 1 further includes a flushing valve 18, which can be integrated with the first pressure-limiting valve 15 and connected to the pilot medium system 2. The flushing valve 18 can be integrated with the heavy oil pressure-limiting valve, i.e., the first pressure-limiting valve 15. Before the engine is shut down, the flushing valve is opened to replace and flush the heavy oil in the common rail pipe with light diesel fuel, ensuring that no residual heavy oil remains in the system pipeline.

[0071] Continue to refer Figure 1 as well as Figure 6 As shown, injection system 100 further includes a control unit 3, which is electrically connected to heavy oil system 1 and pilot medium system 2. It is understood that control unit 3 can be located on the device side of injection system 100, remotely in the cloud, or distributed across both the device side and the cloud, without limitation.

[0072] In some embodiments, the heavy oil supply pump 11 is a rack-type mechanical pump. The control unit 3 is electrically connected to the heavy oil supply pump 11 and controls the rack of the rack-type mechanical pump to maintain a first pressure of the heavy oil in the heavy oil common rail 12. The control unit 3 is electrically connected to the pilot medium pump 21 to maintain a second pressure of the pilot medium in the pilot medium common rail 22. Specifically, a speed governor can be used to pull the rack to adjust the oil supply to achieve closed-loop control of the heavy oil rail pressure. A conventional light diesel common rail pump can be used to perform closed-loop control of the pilot light oil rail pressure. The dual common rail system allows for precise control of both the heavy oil injection pressure and the pilot light oil pressure, improving injection stability. The inventors have creatively combined the advantages of two different existing technical approaches, using a mature mechanical single pump to build up the heavy oil pressure and a speed governor to pull the rack to adjust the oil supply to achieve closed-loop control of the rail pressure. This avoids the existing technical issues of mechanical pumps and the poor reliability of the oil pump solenoid valve in existing common rail systems in terms of heavy oil tolerance, thus achieving a simple and highly reliable heavy oil injection system.

[0073] refer to Figures 2 to 5 As shown, in the first embodiment, the heavy oil fuel injector 13 has a leak-free structure. Its operating principle will be described in detail in the following embodiments describing the heavy oil fuel injector 13. Because the heavy oil fuel injector 13 has a leak-free structure, no heavy oil return is required. Since this leak-free structure requires pressure differential control, the first pressure is greater than the second pressure. This is achieved specifically through the control of the control unit 3. The heavy oil supply pump 11 pressurizes the heavy oil, which then enters the heavy oil common rail 12 through the first pipeline 14. A heavy oil rail pressure sensor, or first rail pressure sensor 17, measures the rail pressure within the common rail 2 in real time. The control unit 3 controls the speed regulator to pull the mechanical pump rack to adjust the oil supply, thereby controlling the rail pressure within the heavy oil common rail 12 and maintaining the first pressure within the heavy oil common rail 12. This rail pressure control method utilizes a mature mechanical pump structure while achieving stable control of injection pressure. The heavy oil pump has a simple and reliable structure, making it easy to retrofit into existing mechanical heavy oil injection systems. It offers low cost and reliable performance. The pilot medium pump 21 pressurizes the pilot light oil, and the control unit 3 controls the pilot medium common rail 22 to maintain a secondary pressure. The control unit 3 also maintains a pressure differential between the heavy oil common rail 12 and the pilot medium common rail 22, maintaining the secondary pressure at a stable value or within a stable range relative to the primary pressure. Dual-rail pressure control enables high-pressure injection throughout the entire injection cycle, ensuring stable and controllable injection and pilot medium pressures, thereby improving injection stability.

[0074] Understand that, Figure 6 as well as Figure 7As shown, the heavy oil fuel injector 13 in the second embodiment has a leaky structure. Its operating principle will be described in detail in the following embodiments of the heavy oil fuel injector 13. Because the heavy oil fuel injector 13 has a leaky structure, it does not need to maintain a rail pressure differential as in the leak-free structure described above, making it easier to control. However, the heavy oil injection system 100 also includes a waste oil pipe 4. This pipe connects to the waste oil passage 36a of the heavy oil fuel injector 13 and receives the mixed waste oil (leaked heavy oil and pilot medium) discharged from the heavy oil fuel injector 13 into the waste oil reservoir 400.

[0075] It can be understood that, regardless of whether it is a leakage structure or a non-leakage structure, the oil circuit structure using a pilot medium for pilot control avoids the heavy oil return passing through the area of ​​the intermediate block where the solenoid valve is set, which makes the solenoid valve used as the pilot control valve have a low service life under heavy oil and high temperature conditions.

[0076] The structure of the heavy oil fuel injector 13 will be described in detail below. It should be understood that the following structure is only an example, and the structure of the heavy oil fuel injector 13 used in the heavy oil injection system 100 is not limited to the content described below.

[0077] The heavy oil fuel injector 13 includes a needle valve assembly 1 a , a pilot valve 2 a , an intermediate block 3 a , a heavy oil passage 4 a , and a pilot medium passage 5 a .

[0078] like Figure 5 As shown, the needle valve assembly 1a includes a needle valve body 11a and a needle valve 12a. The needle valve 12a is disposed in an installation space 110a provided inside the needle valve body 11a. A needle valve gap 113 is defined between the needle valve body 11a and the needle valve 12a.

[0079] The pilot valve 2a includes an armature 21a and an electromagnet 22a. The electromagnet 22a can drive the armature 21a to move.

[0080] The specific structure of the pilot valve 2a can be a ball valve structure 202a, a slide valve structure, a cone valve structure, or Figure 8 The planar valve structures shown are not limited thereto.

[0081] The intermediate block 3a is arranged between the needle valve assembly 1a and the pilot valve 2a. The pilot valve 2a is installed on one side of the intermediate block 3a, and the needle valve assembly 1a is installed on the other side. The intermediate block 3a has a first hole 31a that cooperates with the armature 21a and a second hole 32a that cooperates with the end 121a of the needle valve. The end 211a of the armature and the end 121a of the needle valve are fluidically connected through a control chamber 33a. The other end 123a located at the other end of the needle valve corresponds to the oil injection nozzle 112a provided on the needle valve body 11.

[0082] The specific structure of the intermediate block 3 can be a split structure, that is, the intermediate block 3 includes multiple blocks arranged separately and stacked, including a first intermediate block 301a and a second intermediate block 302a. The first intermediate block 301a provides a first hole 31a. Since the first hole 31a can guide the movement of the armature 21a, the first intermediate block 301a can also be called a guide body. The second intermediate block 302a provides a second hole 32a. The second intermediate block 302a provides a pilot medium oil hole that directly guides the second hole 32a, i.e., a metering hole. Therefore, the second intermediate block 302a can also be called an orifice plate. The use of a split intermediate block can be applied to a wider range of valve structures and has better versatility.

[0083] The intermediate block 3a may also be a single block structure, that is, a plurality of stacked blocks are integrated into a single block, and it is not a simple integration, but the height space occupied by the intermediate block 3a can be reduced. For example, the height space where the first hole and the second hole are set may overlap, without the need to stack the height of the first hole and the second hole as required in the first to fourth embodiments. This saves space in the height direction and makes the structure of the injector more compact.

[0084] The heavy oil passage 4a provides injection fuel for the fuel injector 13 and is connected to the needle valve 12a. The heavy oil liquid pressure provided by the heavy oil passage provides the opening pressure for the needle valve 12a to open relative to the needle valve body 11a.

[0085] The specific structure can be found in Figure 5 As shown, the needle valve 12a includes: an end 121a of the needle valve, and the other end 123a of the needle valve located at the other end, and a middle section 124a located between the end 121a of the needle valve and the other end 123a of the needle valve. The needle valve body 11a is provided with an oil storage tank 111a at a position corresponding to the middle section 124a, and the oil storage tank 111a is directly connected to the heavy oil circuit 4a.

[0086] The pilot medium flow path 5a provides the pilot medium to the fuel injector 13. The pilot medium flow path 5a is connected to the second hole 32a, and the light oil pressure provided by the pilot medium flow path 5 provides the closing pressure that closes the needle valve 12a relative to the needle valve body 11a. The end 121a of the needle valve is connected to an elastic member 122a, and the second hole 32a provides a receiving chamber 321a to accommodate the elastic member 122a. The elastic force of the elastic member 122a and the light oil pressure provided by the pilot medium flow path 5a jointly provide the closing pressure that closes the needle valve 12a relative to the needle valve body 11a. The use of an elastic member, such as a spring structure, makes it easier to control the movement of the needle valve body 11a and can provide a buffering effect on the movement of the needle valve body 11a, thereby improving the movement accuracy and operational reliability of the needle valve body 11a.

[0087] In some embodiments, the fuel injector further includes an injector body 7a having a pressure accumulator chamber 71a. The fuel injector 100a has a light oil high-pressure port 8a and a heavy oil high-pressure port 9a. The pilot medium flow path 5a extends from the light oil high-pressure port 8a through the injector body 7a, the intermediate block 3a, and the second hole 32a. The heavy oil flow path 4a extends from the heavy oil high-pressure port 9a through the pressure accumulator chamber 71a, the intermediate block 3a, the needle valve body 11a, and the needle valve 12a. This compact structure is achieved. Furthermore, the pressure accumulator chamber 71 further stabilizes the heavy oil injection pressure, providing reliable heavy oil injection.

[0088] The control chamber 33a is directly connected to the end portion 121a of the needle valve with equal pressure, and the light oil pressure is configured to be greater than the heavy oil pressure, thereby implementing differential pressure control.

[0089] Here's how it works:

[0090] During the operation of an electronically controlled common rail fuel injector 13, the fuel (here, heavy fuel oil) and pilot oil (light fuel oil) are independently pressure-built to prepare for injection. The pilot oil enters the injector through the light fuel high-pressure port 8, passes through the injector body 7a and the intermediate block 3a (for example, as shown, it passes through the first intermediate block 301a and the second intermediate block 302a in sequence), and ultimately connects with the second orifice 32a. The pilot oil pressure acts on the needle valve end 121a (in the figure, the top of the needle valve 12a), with a force directed downward (closing the needle valve). Heavy fuel enters the injector through the heavy fuel high-pressure port 9a at one end (the top in the figure), first entering the pressure accumulator chamber 71a. At the bottom of the pressure accumulator chamber, it splits into two paths and passes through the intermediate block 3a (for example, as shown, it passes through the first intermediate block 301a and the second intermediate block 302a in sequence), ultimately connecting directly to the oil reservoir 111a. The heavy fuel acts on the needle valve middle section 124a, with a force directed upward (opening the needle valve).

[0091] In the non-injection state, the electromagnet 22a is de-energized, and the armature 21a is not attracted by the electromagnet 22a, but moves downward under the elastic force of the spring 221a corresponding to the electromagnet 22a. The pilot valve 2a is closed, and the pilot oil in the control chamber 33 is pressurized. In the embodiment shown in the figure, the accommodating chamber 321a provided by the second hole 32a and the oil channel 35a together constitute the control chamber 33a, and the stepped hole provided by the first hole 31 constitutes the low-pressure chamber 311a. A ball valve structure is provided between the control chamber 33a and the low-pressure chamber 311a to control the opening and closing. When the opening force of the heavy oil acting on the middle section 124a of the needle valve is less than the liquid pressure of the elastic member 122 and the accommodating chamber 321a, the needle valve is closed and the injector stops spraying oil.

[0092] In the injection state, the electromagnet 22a is energized, the armature 21a moves upward under suction, the balancing valve opens, and the pilot oil in the accommodating chamber 321a located in the second hole 32a enters the control chamber 33a and then enters the low-pressure chamber 311a, thereby releasing pressure. When the opening force of the heavy oil acting on the middle section 124a of the needle valve is greater than the liquid pressure of the elastic member 122a and the accommodating chamber 321a, the needle valve opens and the injector begins to inject the heavy oil as fuel.

[0093] The beneficial effect of using differential pressure control is that the pressure differential ensures that the heavy oil in oil reservoir 111a does not leak into control chamber 33a during the injection period. Specifically, the pilot oil pressure in accommodating chamber 321a is greater than the heavy oil pressure in oil reservoir 111a. Due to the differential pressure, the heavy oil is confined to the middle section 124a of the needle valve, preventing oil backflow. This prevents heavy oil corrosion and high-temperature damage to the electromagnet, reduces the temperature requirements for the injector solenoid valve, and prevents clogging of the pilot oil passage's metering orifice. Furthermore, the injector's heavy oil passage enters the injector from the end (e.g., the top in the figure), flows through the internal flow channel, and descends to the nozzle end. This eliminates heavy oil backflow during operation, eliminating the need for a separate heavy oil return line. The simple heavy oil passage facilitates heavy oil replacement and cleaning.

[0094] refer to Figure 6 As shown, unlike the first embodiment, the second embodiment has a leak-proof structure. A plunger 6a is located between the control chamber 33a and the end 121a of the needle valve. The control chamber 33a is located on one side of the plunger 6a, that is, at the top of the plunger guide section, while the end 121a is located on the other side of the plunger 6a. An intermediate chamber 34a is formed between the plunger 6a and the end 121 of the needle valve. The control chamber 33a and the intermediate chamber 34a are connected via a plunger gap 61a, and the intermediate chamber 34a is connected to the heavy oil passage 4a via a needle valve gap 113a. In this case, the intermediate chamber 34a is a low-pressure chamber. The intermediate chamber 34a is connected to the waste oil passage 36a. The light oil and heavy oil that merge in the intermediate chamber 34a can be discharged through the waste oil passage 36a to the waste oil reservoir 400. In the sixth embodiment, the light oil pressure is not configured to be greater than the heavy oil pressure. The needle valve clearance and plunger clearance mentioned above refer to the clearance range of the shaft-hole fit. It can be understood that the use of a leaky structure can still ensure that heavy oil does not enter the control chamber, and can still protect the solenoid valve, avoiding corrosion and high-temperature damage to the electromagnet by heavy oil, and reducing the temperature requirements for the injector solenoid valve.

[0095] It can be understood that the effect of this is that the corresponding control of the fuel injector is relatively simple, and there is no need to maintain pressure difference control. However, in comparison, the need to set up a waste oil circuit will make the structure of the system and the fuel injector more complicated.

[0096] As described above, the present application further provides a fuel injection method, which uses the heavy oil fuel injection system 100 described in the above embodiment to perform fuel injection.

[0097] S100. When the engine is started, the engine is heated by circulating cooling water, the cooling water temperature is not less than 60°C, and the heavy oil fuel is heated to the working viscosity;

[0098] Specifically, the engine can be a diesel engine, and the cooling water temperature needs to be heated to no less than 60°C. The cooling water circulates within the diesel engine to preheat the fuel injectors 13. The heavy oil fuel in the heavy oil storage unit 200 (e.g., a heavy oil daily tank) is heated to the operating viscosity, and the injectors are heated and circulated. Furthermore, for fuel injectors with injector cooling channels, such as those using lubricating oil cooling channels to cool the injectors, the cooling water in the cylinder liner can heat the lubricating oil during startup, thereby preheating the injectors. In other words, the injector cooling oil preheated by the cylinder liner cooling water is used to heat the injectors.

[0099] S200. When the engine needs to use light oil as fuel in certain scenarios, the fuel injector 13 injects light oil as fuel, and the heavy oil in the heavy oil circuit 4a of the fuel injector 13 is switched to light oil. The light oil is preheated to a predetermined temperature, for example, the light oil in the light oil daily cabinet is heated. At the predetermined temperature, the light oil will not vaporize and be input to the heavy oil circuit 4a, and the heating is gradually stopped after switching to light oil, so that the light oil input to the heavy oil circuit 4a gradually decreases from the predetermined temperature at the initial switching moment to the unheated normal temperature, and the light oil in the unheated light oil daily cabinet is directly used for operation. This can prevent the deformation and jamming of the coupling parts due to temperature changes at the switching moment and in the initial stage of the switching.

[0100] S300. When the engine needs to switch from light oil mode to heavy oil mode, and when the light oil in the heavy oil circuit of the fuel injector is switched to heavy oil, the heavy oil daily cabinet should first be used to heat the heavy oil to the operating temperature, and at the same time, the heating of the cooling water should be started in advance to a first temperature, which is less than 60°C, for example, 40°C. After that, the light oil is cut off and the heavy oil is connected. Within the time period when the light oil remaining in the system is consumed, the cooling water temperature is heated to above 60°C.

[0101] Specifically, you can slightly start the heating in advance to raise the diesel engine temperature to above 40°C, then connect the heavy oil and cut off the light oil. The heavy oil temperature should be heated to the required heavy oil temperature within the time it takes to consume the light oil in the system.

[0102] In summary, the beneficial effects of the fuel injector, injection system, injection method, and engine introduced above include but are not limited to: by adopting a dual common rail structure with independent heavy oil common rail and pilot light oil common rail, precise control of heavy oil injection pressure and pilot light oil pressure can be achieved, thereby improving injection stability; the injector eliminates the traditional hydraulic amplification mechanism, and directly controls heavy oil injection through pilot light oil pressure buildup and pressure relief, thereby improving injection response, and has a simple and reliable structure.

[0103] Although the present invention is disclosed above with reference to preferred embodiments, this 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 modifications, equivalent variations, and modifications made to the above embodiments in accordance with 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 heavy oil injection system (100), characterized in that: include: A heavy oil system (1) comprises a heavy oil supply pump (11), a heavy oil common rail pipe (12), and a heavy oil fuel injector (13), and a first pipeline (14) connecting the heavy oil supply pump (11), the heavy oil common rail pipe (12), and the heavy oil fuel injector (13); The pilot medium system (2) comprises a pilot medium pump (21), a pilot medium common rail pipe (22), and a second pipeline (23) connecting the pilot medium pump (21), the pilot medium common rail pipe (22) and the heavy oil fuel injector (13). The pilot medium system (2) provides a pilot medium to the heavy oil fuel injector (13) for pilot control.

2. The heavy oil injection system (100) according to claim 1, characterized in that The fuel oil circuit provided by the heavy oil injection system (100) includes: The heavy oil is pressurized by the heavy oil supply pump (11) and enters the heavy oil common rail (12) through the first pipeline (14), a first pressure is maintained in the heavy oil common rail (12), and the heavy oil at the first pressure enters the heavy oil oil circuit of the heavy oil fuel injector (13) through the first pipeline (14), providing the heavy oil as fuel injection; The pilot medium is pressurized by the pilot medium pump (21) and then enters the pilot medium common rail (22) through the second pipeline (23). A second pressure is maintained in the pilot medium common rail (22), and the pilot medium at the second pressure enters the pilot medium flow path of the heavy oil fuel injector (13) through the second pipeline (23), providing pilot control of the fuel injection of the heavy oil fuel injector (13).

3. The heavy oil injection system (100) according to claim 2, characterized in that: The heavy oil system (1) further includes a first pressure limiting valve (15), a first flow limiting valve (16), and a first rail pressure sensor (17); the pilot medium system (2) further includes a second pressure limiting valve (24) and a second rail pressure sensor (25).

4. The heavy oil injection system (100) according to claim 3, characterized in that: The heavy oil system (1) further comprises a flushing valve (18), wherein the flushing valve (18) is integrated with the first pressure limiting valve (15), and the flushing valve (18) is connected to the pilot medium system (2).

5. The heavy oil injection system (100) according to claim 2, characterized in that: The injection system (100) further comprises a control unit (3), wherein the control unit (3) is electrically connected to the heavy oil system (1) and the pilot medium system (2), respectively.

6. The heavy oil injection system (100) according to claim 5, characterized in that: The heavy oil supply pump (11) is a rack-type mechanical pump. The control unit (3) is electrically connected to the heavy oil supply pump (11) to control the rack of the rack-type mechanical pump so that the heavy oil maintains a first pressure in the heavy oil common rail pipe (12); and the control unit (3) is electrically connected to the pilot medium pump (21) so that the pilot medium maintains a second pressure in the pilot medium common rail pipe (22).

7. The heavy oil injection system (100) according to claim 2, characterized in that: The heavy oil fuel injector (13) is a leak-free structure, and the first pressure is greater than the second pressure.

8. The heavy oil injection system (100) according to claim 2, characterized in that: The heavy oil fuel injector (13) has a leakage structure. The heavy oil injection system (100) further includes a waste oil circuit (4). The waste oil circuit (4) is connected to the heavy oil fuel injector (13) and receives mixed waste oil of leaked heavy oil and pilot medium discharged from the heavy oil fuel injector (13).

9. The heavy oil injection system (100) according to claim 1, characterized in that: The pilot medium is light oil.

10. A heavy oil injection method, characterized in that: Used in the heavy oil injection system (100) according to any one of claims 1 to 9.

11. An engine (1000), characterized in that: It comprises a heavy oil injection system (100) according to any one of claims 1 to 9, wherein the cylinders of the engine are correspondingly provided with the heavy oil fuel injectors (13).

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