A dual-fuel injector and internal combustion engine

Abstract

This invention belongs to the field of injector manufacturing technology and discloses a dual-fuel injector and an internal combustion engine. It includes an injection body and an injection control unit. The injection control unit is installed at one end of the injection body, and a gas injection port is located at the other end. A needle valve is slidably installed on the injection body. A valve body is slidably sleeved on the side of the needle valve near the gas injection port. A fuel injection port is opened at the end of the valve body. A first oil inlet channel is opened along the axial direction inside the needle valve. An oil reservoir is formed between the needle valve and the valve body. When the dual-fuel injector is in the open state, the first oil inlet channel communicates with the fuel injection port through the oil reservoir, the oil inlet communicates with the first oil inlet channel, and the air inlet communicates with the gas injection port through the air reservoir. This invention solves the problem in the prior art where some fuel leaks out when the injector injects gas, or high-pressure fuel flows backward into the air inlet and air source, causing the engine to malfunction.

Description

Technical Field

[0001] This invention relates to the field of injector manufacturing technology, and more particularly to a dual-fuel injector and an internal combustion engine. Background Technology

[0002] In the commercial vehicle sector, the engine, as the core power unit of the entire vehicle, directly determines the vehicle's commercial value and market competitiveness through its performance and operating costs. Traditional engines rely on a single fossil fuel, converting the chemical energy contained in the fuel into the mechanical energy required to drive the vehicle through an internal combustion process. However, the volatility of the global energy market and increasingly stringent environmental regulations continue to drive up vehicle fuel costs, making the reduction of long-term operating costs a core issue of common concern for both manufacturers and end users. To effectively address this challenge and significantly reduce energy consumption costs throughout the entire life cycle of commercial vehicles, thereby improving their economic efficiency, a key direction of technological development focuses on the diversification and flexibility of engine fuel supply systems. Currently, a widely adopted and deeply developed solution is the use of a dual-fuel supply system of gasoline and natural gas. This innovative design allows a single engine platform to work collaboratively or switch between two distinct fuel modes. Specifically, this system allows the engine to intelligently select or proportionally mix traditional liquid fuels (such as diesel) and gaseous fuels (such as natural gas or liquefied petroleum gas) based on real-time fuel availability, market prices, and operating conditions. Through sophisticated electronic control units and optimized fuel injection strategies, the engine can maintain a highly efficient and stable combustion process in both fuel modes, ensuring reliable and smooth power output. The core advantage of this dual-fuel operating mode lies in giving vehicle operators greater autonomy in fuel selection, allowing them to fully utilize the cost differences between different fuels and proactively mitigate the risks of drastic fluctuations in the price of a single energy source, thereby fundamentally reducing energy consumption costs per unit mileage. Therefore, developing and optimizing engines and their control systems that can operate efficiently, reliably, and seamlessly switch between fuel and gas modes has become a key path and urgent need for continuous innovation in commercial vehicle power technology, reducing user operating costs, and enhancing overall product competitiveness.

[0003] The aforementioned engine requires a dual-fuel injector for injection, which necessitates the injector to separately control the injection of natural gas and fuel. During operation, the fuel injected by the injector is at a high pressure. Typically, a fuel reservoir is formed by the needle valve inside the injector and the valve body outside the needle valve. Fuel is supplied to the fuel reservoir through a fuel line. The fuel reservoir sprays fuel to the outside under the control of a solenoid valve. The gas reservoir is usually located between the valve body and the surrounding components. However, the fuel line needs to pass through the components outside the valve body and the valve body to enter the fuel reservoir. There are assembly gaps between the internal components of the injector. Since the fuel line and the gas reservoir are relatively close, the high-pressure fuel will directly enter the gas reservoir along the assembly gaps. This can also cause high-pressure fuel to backflow towards the air intake and air source, resulting in fuel being sprayed out during the injector's natural gas injection process. Consequently, the injector's injection volume becomes inaccurate, leading to engine malfunction. Summary of the Invention

[0004] The purpose of this invention is to provide a dual-fuel injector and internal combustion engine, which solves the problem that in the prior art, some fuel may leak out when the injector injects gas, or high-pressure fuel may flow backward into the air intake and air source, causing the engine to malfunction.

[0005] To achieve this objective, the present invention adopts the following technical solution: The present invention provides a dual-fuel injector, including an injection body and an injection control unit. The injection control unit is installed at one end of the injection body, and a gas injection port is provided at the other end. A needle valve is slidably installed on the injection body. A valve body is slidably sleeved on the side of the needle valve near the gas injection port. A fuel injection port is provided at the end of the valve body. A first oil inlet channel is provided in the needle valve along the axial direction. An oil storage chamber is formed between the needle valve and the valve body. When the needle valve is open, the first oil inlet channel communicates with the fuel injection port through the oil storage chamber. An oil inlet is provided on the side of the injection body near the injection control unit. The oil inlet communicates with the first oil inlet channel. An air storage chamber is formed between the injection body and the valve body. When the valve body is raised, an air inlet is provided on the injection body. The air inlet communicates with the gas injection port through the air storage chamber. The injection control unit can control the opening and closing of the fuel injection port and the gas injection port.

[0006] Preferably, the injection body has an oil return port, the needle valve has a first oil return pipeline inside, the oil return port is connected to the first oil return pipeline, and the needle valve has an oil return groove on its outer wall, the first oil return pipeline is connected to the oil return groove.

[0007] Preferably, an opening is formed on the lower side of the injection body, a section of the valve body is inserted into the opening, the fuel injection port is provided on the area of ​​the valve body exposed outside the opening, the needle valve abuts against the inner wall of the valve body, and the valve body covers the gas injection port.

[0008] Preferably, the valve body and the injection body form an interlocking fit, the annular cavity formed by the valve body and the injection body communicates with the air storage cavity, and a first spring is installed in the mounting cavity on the upper side of the valve body, with the other side of the first spring abutting against a protrusion on the inner side of the injection body.

[0009] Preferably, the injection control unit includes a first inner cavity and an oil control port. An oil control plate is installed in the first inner cavity, and a first pressure relief hole is opened on the oil control plate. An oil control valve is installed on the lower side of the oil control plate, and an oil control electromagnet controls the movement of the oil control valve. The first inner cavity is connected to the mounting cavity through a first connecting pipe, and the oil control port is connected to the first pressure relief hole.

[0010] Preferably, a second oil return pipe is provided on the side wall of the first inner cavity, and the second oil return pipe is connected to the oil return port.

[0011] Preferably, the injection control unit includes a second inner cavity, in which an injection plate is installed. The injection plate has a second pressure relief hole. An injection valve is installed on the upper side of the injection plate. An injection solenoid controls the movement of the injection valve. The lower side of the injection plate communicates with the upper side of the needle valve to form a flow cavity. The oil inlet communicates with the flow cavity, and the flow cavity communicates with the second pressure relief hole.

[0012] Preferably, a third oil return pipe is provided on the inner wall of the upper side of the oil spray plate, and the third oil return pipe is connected to the oil return port.

[0013] Preferably, the needle valve has a protrusion in the middle section, and a second spring is installed on the upper side of the protrusion, the second spring abutting against the inner wall of the injection body.

[0014] An internal combustion engine includes a combustion chamber and a dual-fuel injector as described above, wherein the fuel injection port and the gas injection port are selectively connected to the combustion chamber.

[0015] Beneficial effects: By changing the position of the first oil inlet channel, the flow of the first oil inlet channel is directed along the inside of the needle valve, avoiding the opening of the first oil inlet channel near the air reservoir. This increases the position of the first oil inlet channel and the oil inlet relative to the air reservoir, reducing the degree of oil leakage from the gap between the valve body and the injection body into the air reservoir. At the same time, it can stabilize the pressure in the air reservoir and stabilize the pressure fluctuations in the jet control chamber, reducing the fluctuation amplitude. This makes the injection of the dual-fuel injector more precise, thereby enabling the engine to operate normally. Attached Figure Description

[0016] Figure 1 This is a cross-sectional view of the dual-fuel injector of the present invention;

[0017] Figure 2 This is an enlarged cross-sectional view of the injection control unit of the present invention;

[0018] Figure 3 This is an enlarged cross-sectional view of the gas injection port of the present invention;

[0019] Figure 4 This is an enlarged view of the cross-section of the oil return groove of the present invention.

[0020] In the diagram: 1. Injection body; 2. Injection control unit; 3. Gas injection port; 4. Fuel injection port; 5. Needle valve; 6. Valve body; 7. First oil inlet channel; 8. Oil reservoir; 9. Oil inlet; 10. Gas reservoir; 11. Air inlet; 12. Oil return port; 13. First oil return line; 14. Oil return groove; 15. First spring; 16. First inner cavity; 17. Oil control port; 18. Oil control plate; 19. First pressure relief hole; 20. Oil control valve; 21. Oil control solenoid; 22. Second oil return line; 23. Second inner cavity; 24. Injection plate; 25. Second pressure relief hole; 26. Injection valve; 27. Injection solenoid; 28. Third oil return line; 29. ​​Second spring. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0022] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0023] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0024] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0025] In dual-fuel engines for commercial vehicles, the dual-fuel injectors need to independently control fuel and gas injection. High-pressure fuel is stored in a reservoir enclosed by an internal needle valve and an external valve body, supplied through a fuel line, and injected under the control of a solenoid valve. The gas reservoir is typically located between the valve body and its surrounding components. The key issue is that to supply fuel to the reservoir, the fuel line must pass sequentially through the valve body's surrounding components and the valve body itself. Due to unavoidable assembly gaps between the injector's internal components and the proximity of the fuel line to the gas reservoir, high-pressure fuel can easily leak through these tiny gaps during delivery, directly intruding into the gas reservoir. This results in the injector injecting fuel simultaneously when the engine is operating in gas injection mode, instead of only injecting gas. This unexpected fuel contamination severely interferes with the precise metering of gas injection, causing uncontrolled injection volume and ultimately disrupting the engine's normal combustion process and operating state.

[0026] To solve the above problems, such as Figures 1 to 4As shown, the present invention provides a dual-fuel injector, including an injection body 1 and an injection control unit 2. The injection control unit 2 is installed at one end of the injection body 1, and a gas injection port 3 is at the other end. A needle valve 5 is slidably installed on the injection body 1. A valve body 6 is slidably sleeved on the side of the needle valve 5 near the gas injection port 3. A fuel injection port 4 is opened at the end of the valve body 6. A first oil inlet channel 7 is opened in the needle valve 5 along the axial direction. An oil storage chamber 8 is formed between the needle valve 5 and the valve body 6. When the needle valve 5 is in the open state and raised, the first oil inlet channel 7 communicates with the fuel injection port 4 through the oil storage chamber 8. An oil inlet 9 is opened on the side of the injection body 1 near the injection control unit 2. The oil inlet 9 communicates with the first oil inlet channel 7. The injection body 1 and the valve body 6 form an air storage chamber 10. An air inlet 11 is opened on the injection body 1. When the valve body 6 is in the open state and raised, the air inlet 11 communicates with the gas injection port 3 through the air storage chamber 10. The injection control unit 2 can control the opening and closing of the fuel injection port 4 and the gas injection port 3.

[0027] The needle valve 5 slides downwards and abuts against the valve body 6, thus closing the fuel injection port 4. The valve body 6 slides downwards and abuts against the inclined surface inside the injection body 1, thus closing the gas injection port 3. By moving the valve body 6 and the needle valve 5 up and down, the opening and closing of the fuel injection port 4 and the gas injection port 3 can be flexibly controlled. In order to prevent fuel from entering the gas storage chamber 10, the first oil inlet channel 7 and the oil inlet 9 are opened at a position away from the gas storage chamber 10. The first oil inlet channel 7 is opened inside the needle valve 5. The high-pressure oil entering the needle valve 5 enters the needle valve 5 from the top of the needle valve 5. The high-pressure oil entering the dual-fuel injector is longer from the gas storage chamber 10, which also prevents the high-pressure oil from diffusing into the gas storage chamber 10. This can prevent fuel from diffusing into the gas storage chamber 10, and at the same time, it can stabilize the pressure in the gas storage chamber, reduce the fluctuation of gas, and improve the accuracy of the dual-fuel injector in injecting gas or fuel.

[0028] The main body of the injection unit 1 is provided with an oil return port 12, and the needle valve 5 is provided with a first oil return pipeline 13. The oil return port 12 is connected to the first oil return pipeline 13. The needle valve 5 is provided with an oil return groove 14 on its outer wall. The oil return groove 14 of the present invention is located at a position higher than the oil storage chamber 8 and lower than the top surface of the valve body 6. The first oil return pipeline 13 is connected to the oil return groove 14.

[0029] The needle valve 5 and valve body 6 form an oil reservoir 8. The first oil inlet channel 7 delivers fuel into the oil reservoir 8. The bottom of the oil reservoir 8 is connected to the fuel injection port 4. The outer wall of the needle valve 5 at the top of the oil reservoir 8 is provided with a return oil groove 14. The upward diffused fuel will enter the first return oil line 13 along the return oil groove 14 and finally be discharged to the outside from the return oil port 12. This prevents the fuel from entering the air reservoir 10 along the assembly gap, thereby reducing the amount of fuel entering the air reservoir 10, improving the injection accuracy of the dual fuel injector, enabling the engine to work normally, and increasing its working efficiency.

[0030] An opening is formed on the lower side of the injection body 1. A section of the valve body 6 is inserted into the opening. A fuel injection port 4 is provided on the area of ​​the valve body 6 exposed outside the opening. The needle valve 5 abuts against the inner wall of the valve body 6. The valve body 6 is covered by the gas injection port 3.

[0031] The valve body 6 has an area with a fuel injection port 4 exposed to the outside to facilitate fuel injection. During the injection process, the fuel and gas pipelines are independent of each other and can be injected separately. Gas is injected from the outside of the valve body 6, and fuel is injected from the inside of the valve body 6. The valve body 6 can effectively separate gas and fuel, allowing the engine to operate under different conditions. There are three combustion modes: pure fuel, fuel ignition gas, and pure gas. Customers can choose the operating mode according to specific conditions to provide the most economical use mode.

[0032] The valve body 6 and the injection body 1 are fitted together by a coupling. This coupling allows the valve body 6 to move up and down within the injection body 1, forming an annular cavity that communicates with the gas storage chamber 10. The gas in the gas storage chamber 10 controls the up and down movement of the valve body 6. A first spring 15 is installed in the mounting cavity on the upper side of the valve body 6, and the other side of the first spring 15 abuts against a protrusion on the inner side of the injection body 1. The first spring 15 keeps the valve body 6 and the injection body 1 in a normally closed state, preventing gas leakage.

[0033] The injection control unit 2 includes a first inner cavity 16 and an oil control port 17. An oil control plate 18 is installed in the first inner cavity 16. A first pressure relief hole 19 is opened on the oil control plate 18. An oil control valve 20 is installed on the lower side of the oil control plate 18. An oil control solenoid 21 controls the movement of the oil control valve 20. The first inner cavity 16 is connected to the mounting cavity through a first connecting pipe. The oil control port 17 is connected to the first pressure relief hole 19.

[0034] The injection control unit 2 includes a second inner cavity 23, within which an injection plate 24 is installed. A second pressure relief hole 25 is provided on the injection plate 24. An injection valve 26 is installed on the upper side of the injection plate 24. An injection solenoid 27 controls the movement of the injection valve 26. The lower side of the injection plate 24 communicates with the upper side of the needle valve 5 to form a flow chamber. The oil inlet 9 communicates with the flow chamber, and the flow chamber communicates with the second pressure relief hole 25.

[0035] When control oil enters the first pressure relief hole 19, if the control solenoid 21 attracts the control valve 20, the ball on the control valve 20 separates from the first pressure relief hole 19, the pressure in the first inner cavity 16 will decrease, thereby reducing the pressure of the control oil entering the mounting cavity. The gas in the gas storage cavity 10 pushes the valve body 6 upward. At the same time, the injection solenoid 27 is activated, causing the ball on the injection valve 26 to separate from the second pressure relief hole 25, reducing the pressure in the second inner cavity 23. This allows the fuel in the oil storage cavity 8 to push the needle valve 5 upward, ultimately allowing the needle valve 5 and the valve body 6 to move upward simultaneously, and the gas can be injected from the gas injection port 3. In fuel mode, the injection solenoid 27 needs to be activated, causing the ball on the injection solenoid 27 to open the second pressure relief hole 25, reducing the pressure in the second inner cavity 23, causing the fuel to push the needle valve 5 upward and separate it from the valve body 6, ultimately enabling the fuel to be injected.

[0036] A second return oil pipe 22 is provided on the side wall of the first inner cavity 16, and the second return oil pipe 22 is connected to the return oil port 12. A third return oil pipe 28 is provided on the inner wall of the upper side of the fuel injection plate 24, and the third return oil pipe 28 is connected to the return oil port 12. By setting the second return oil pipe 22 and the third return oil pipe 28, fuel accumulation inside the dual-fuel injector is prevented, and fuel leakage into the gas storage chamber 10 is prevented, thereby improving the working accuracy of the dual-fuel injector.

[0037] The needle valve 5 has a protrusion in its middle section, and a second spring 29 is installed on the upper side of the protrusion. The second spring 29 abuts against the inner wall of the injection body 1. By setting the second spring 29, the needle valve 5 can be made to abut against the valve body 6, preventing fuel leakage during non-injection processes.

[0038] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A dual-fuel injector, characterized in that, The system includes an injection body (1) and an injection control unit (2). The injection control unit (2) is installed at one end of the injection body (1), and a gas injection port (3) is provided at the other end. A needle valve (5) is slidably installed on the injection body (1). A valve body (6) is slidably sleeved on the side of the needle valve (5) near the gas injection port (3). A fuel injection port (4) is provided at the end of the valve body (6). A first oil inlet channel (7) is provided in the needle valve (5) along the axial direction. An oil storage chamber (8) is formed between the needle valve (5) and the valve body (6). When the needle valve (5) is opened, the first oil inlet channel (7) is filled with fuel. The oil storage chamber (8) is connected to the fuel injection port (4). The injection body (1) has an oil inlet (9) on the side near the injection control unit (2). The oil inlet (9) is connected to the first oil inlet channel (7). The injection body (1) and the valve body (6) form an air storage chamber (10). An air inlet (11) is provided on the injection body (1). When the valve body (6) is raised, the air inlet (11) is connected to the gas injection port (3) through the air storage chamber (10). The injection control unit (2) can control the opening and closing of the fuel injection port (4) and the gas injection port (3). The main body of the injection unit (1) is provided with an oil return port (12), the needle valve (5) is provided with a first oil return pipeline (13), the oil return port (12) is connected to the first oil return pipeline (13), the needle valve (5) is provided with an oil return groove (14) on its outer wall, and the first oil return pipeline (13) is connected to the oil return groove (14). An opening is formed on the lower side of the injection body (1), a section of the valve body (6) is inserted into the opening, the fuel injection port (4) is provided on the area of ​​the valve body (6) exposed outside the opening, the needle valve (5) abuts against the inner wall of the valve body (6), and the valve body (6) covers the gas injection port (3). The valve body (6) and the injection body (1) form a pair. The annular cavity formed by the valve body (6) and the injection body (1) is connected to the air storage cavity (10). A first spring (15) is installed in the mounting cavity on the upper side of the valve body (6). The other side of the first spring (15) abuts against the protrusion on the inner side of the injection body (1).

2. The dual-fuel injector according to claim 1, characterized in that, The injection control unit (2) includes a first inner cavity (16) and an oil control port (17). An oil control plate (18) is installed in the first inner cavity (16). A first pressure relief hole (19) is opened on the oil control plate (18). An oil control valve (20) is installed on the lower side of the oil control plate (18). An oil control electromagnet (21) controls the movement of the oil control valve (20). The first inner cavity (16) is connected to the mounting cavity through a first connecting pipe. The oil control port (17) is connected to the first pressure relief hole (19).

3. The dual-fuel injector according to claim 2, characterized in that, The side wall of the first inner cavity (16) is provided with a second oil return pipe (22), which is connected to the oil return port (12).

4. The dual-fuel injector according to claim 1, characterized in that, The injection control unit (2) includes a second inner cavity (23), and an oil spray plate (24) is installed in the second inner cavity (23). A second pressure relief hole (25) is provided on the oil spray plate (24). An oil spray valve (26) is installed on the upper side of the oil spray plate (24). An oil spray electromagnet (27) controls the movement of the oil spray valve (26). The lower side of the oil spray plate (24) is connected to the upper side of the needle valve (5) to form a flow cavity. The oil inlet (9) is connected to the flow cavity. The flow cavity is connected to the second pressure relief hole (25).

5. The dual-fuel injector according to claim 4, characterized in that, The inner wall of the upper side of the spray plate (24) is provided with a third oil return pipe (28), which is connected to the oil return port (12).

6. The dual-fuel injector according to claim 1, characterized in that, The needle valve (5) has a protrusion in the middle section, and a second spring (29) is installed on the upper side of the protrusion. The second spring (29) abuts against the inner wall of the spray body (1).

7. An internal combustion engine, characterized in that, It includes a combustion chamber and a dual-fuel injector as described in claim 1, wherein the fuel injection port (4) and the gas injection port (3) are selectively connected to the combustion chamber.

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