Dual fuel injector, its design method and injection control method

Abstract

The present invention relates to the technical field of engines, and specifically discloses a dual-fuel injector, its design method and injection control method. The dual-fuel injector forms a gas injection channel through an oil injection valve seat and a gas injection valve seat to directly inject gas into the combustion chamber. The injection of gas is more uniform, and the extending direction of the gas injection cavity of the gas injection channel is parallel to or inclined towards the central axis of the dual-fuel injector, so that more gas is injected into the combustion chamber pit, improving the combustion speed, thereby improving the thermal efficiency while avoiding the deterioration of emissions. Moreover, the axis of the fuel injection hole is arranged at an angle to the central axis, which can more quickly achieve the ignition of gas by fuel and realize the improvement of thermal efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of engines, and particularly to a dual-fuel injector, a design method thereof, and an injection control method thereof. Background Art

[0002] Existing dual-fuel engines usually adopt a dual-injector solution, where one injector is used to inject fuel and the other injector is used to inject gas. The gas is ignited by the fuel for combustion, thereby achieving energy conservation and emission reduction. However, the injection control of the dual injectors is not easy to synchronize, so that a good injection and mixing effect cannot be achieved. In this regard, a dual-fuel injector is provided in the prior art, which integrates the functions of fuel injection and gas injection on the same injector, thereby ensuring synchronous injection. However, the fuel injection and gas injection structures of the existing dual-fuel injectors are both porous injections, and the directions of the injected fuel jets and gas jets are parallel. As a result, most of the injected gas is injected at the edge of the combustion chamber. The corresponding fuel-gas mixing cloud map is as Figure 1 shown. After the dual-fuel injector injects, as the crankshaft rotates, the fuel and gas are mixed in the combustion chamber. However, the mixed fuel is relatively dispersed in the combustion chamber, and there is less fuel concentrated in the combustion chamber pit, resulting in a slow combustion speed, reduced thermal efficiency, and deteriorated emissions. In addition, since the fuel jets and gas jets are parallelly injected, the distance between them is relatively far, and the ignition effect of the fuel on the gas is poor, reducing the thermal efficiency. Summary of the Invention

[0003] The purpose of the present invention is to provide a dual-fuel injector, a design method thereof, and an injection control method thereof, so as to solve the problems of low thermal efficiency and deteriorated emissions caused by the structure of the existing dual-fuel injector.

[0004] The present invention provides a dual-fuel injector, including an oil injection valve core, an oil injection valve seat, and a gas injection valve seat;

[0005] The oil injection valve seat is provided with an oil injection channel, the oil injection valve core is located in the oil injection channel, the oil injection valve core can move relative to the oil injection valve seat to open or close the oil injection channel, and the oil injection valve seat is provided with an oil injection hole, and the oil injection hole is communicated with the oil injection channel and is used for injecting fuel into the combustion chamber;

[0006] The gas injection valve seat is sleeved outside the oil injection valve seat, a gas injection channel is formed between the oil injection valve seat and the gas injection valve seat, the gas injection channel includes an adjustment chamber and a gas injection chamber, the opening degree of the adjustment chamber increases or decreases as the oil injection valve seat moves up and down relative to the gas injection valve seat, and the gas injection chamber is used for injecting gas into the combustion chamber;

[0007] The axis of the fuel injection hole is arranged at an angle to the central axis of the dual-fuel injector. Along the flow direction of the gas, the extending direction of the jet cavity is parallel to the central axis or inclined towards the central axis.

[0008] As a preferred technical solution of the dual-fuel injector, the jet passage further includes a pressure stabilizing cavity, and the regulating cavity and the jet cavity are communicated through the pressure stabilizing cavity.

[0009] As a preferred technical solution of the dual-fuel injector, the maximum width of the regulating cavity is greater than or equal to the width of the jet cavity.

[0010] As a preferred technical solution of the dual-fuel injector, along the direction of the central axis, the length of the jet cavity is greater than the length of the pressure stabilizing cavity, and the length of the pressure stabilizing cavity is greater than the length of the regulating cavity.

[0011] As a preferred technical solution of the dual-fuel injector, along the flow direction of the gas, the jet cavity is successively provided with an inlet section, an acceleration section and a spraying section. The inlet section is of a flared structure, the large end of the inlet section is communicated with the pressure stabilizing cavity, the acceleration section is communicated with the small end of the inlet section, the spraying section is provided with a straight wall on one side of the jet valve seat and an inclined wall on one side of the fuel injection valve seat, and the inclined wall is inclined towards the direction close to the central axis.

[0012] As a preferred technical solution of the dual-fuel injector, the included angle between the inclined wall of the spraying section on one side of the fuel injection valve seat and the horizontal direction is less than 60°.

[0013] As a preferred technical solution of the dual-fuel injector, the pressure stabilizing cavity is provided with a straight wall on one side of the fuel injection valve seat, the upper section of the pressure stabilizing cavity on one side of the jet valve seat is provided with a straight wall, and the lower section is provided with an inclined wall and extends downward to form the inclined wall of the inlet section on one side of the jet valve seat. The included angle between the inclined wall of the inlet section on one side of the fuel injection valve seat and the horizontal direction is greater than the included angle between the inclined wall of the inlet section on one side of the jet valve seat and the horizontal direction.

[0014] As a preferred technical solution of the dual-fuel injector, the included angle between the inclined wall of the inlet section on one side of the fuel injection valve seat and the horizontal direction is greater than or equal to 45° and less than or equal to 60°, and the included angle between the inclined wall of the inlet section on one side of the jet valve seat and the horizontal direction is greater than or equal to 45° and less than or equal to 60°.

[0015] The present invention provides a design method for a dual-fuel injector, which is used for structurally designing the dual-fuel injector of any of the above solutions. The design method of the dual-fuel injector includes:

[0016] Establishing a simulation model of the dual-fuel injector;

[0017] Adjust the number and / or diameter of the fuel injection holes so that the fuel penetration distance is within a first preset range;

[0018] Adjust the width of the gas jet channel so that the gas penetration distance is within a second preset range;

[0019] Adjust the angle between the axis of the fuel injection hole and the central axis according to the ignition effect of the fuel on the gas.

[0020] As a preferred technical solution of the design method of the dual-fuel injector:

[0021] The method for adjusting the number and diameter of the fuel injection holes includes:

[0022] When the fuel penetration distance is less than the minimum value of the first preset range, reduce the number and / or diameter of the fuel injection holes until the fuel penetration distance is within the first preset range;

[0023] When the fuel penetration distance is greater than the maximum value of the first preset range, increase the number and / or diameter of the fuel injection holes until the fuel penetration distance is within the first preset range;

[0024] The method for adjusting the width of the gas jet channel includes:

[0025] When the gas penetration distance is less than the minimum value of the second preset range, reduce the width of the gas jet channel until the gas penetration distance is within the second preset range;

[0026] When the gas penetration distance is greater than the maximum value of the second preset range, increase the width of the gas jet channel until the gas penetration distance is within the second preset range.

[0027] As a preferred technical solution of the design method of the dual-fuel injector, the adjustment range of the angle between the axis of the fuel injection hole and the central axis is 10° - 45°.

[0028] The present invention provides an injection control method for a dual-fuel injector, which is applied to the dual-fuel injector of the above solution. The injection control method of the dual-fuel injector includes:

[0029] Calculate the required gas flow according to the required gas intake and the engine speed;

[0030] Determine the distance that the fuel injection valve seat moves relative to the gas injection valve seat according to the corresponding relationship between the distance that the fuel injection valve seat of the dual-fuel injector moves relative to the gas injection valve seat and the gas flow.

[0031] The beneficial effects of the present invention are:

[0032] The present invention provides a dual-fuel injector, which forms a gas jet channel through an oil injection valve seat and a gas jet valve seat to directly inject gas into the combustion chamber. The injection of gas is more uniform, and the extending direction of the gas jet cavity of the gas jet channel is parallel to or inclined towards the central axis of the dual-fuel injector, so that more gas is injected into the combustion chamber pit, improving the combustion speed, thereby enhancing the thermal efficiency while avoiding the deterioration of emissions. Moreover, the axis of the oil injection hole is arranged at an angle with the central axis, which can achieve the ignition of gas by fuel faster and realize the improvement of thermal efficiency.

[0033] The present invention provides a design method for a dual-fuel injector, which adjusts the number and diameter of the oil injection holes so that the fuel penetration distance is within a first preset range; adjusts the width of the gas jet channel so that the gas penetration distance is within a second preset range; and adjusts the angle between the axis of the oil injection hole and the central axis to enable the fuel to ignite the gas faster and realize the improvement of thermal efficiency. And by designing the dual-fuel injector through this method, it can be applied to combustion chambers with different structures and sizes.

[0034] The present invention provides a jet control method for a dual-fuel injector, which calculates the required gas flow rate according to the required gas intake and the engine speed, and determines the opening degree of the gas jet channel, so that the injection response during gas injection is more rapid and the injection control accuracy is higher. Description of the Drawings

[0035] Figure 1 It is a cross-sectional view of the dual-fuel injector in the closed state in an embodiment of the present invention;

[0036] Figure 2 It is a cross-sectional view of the dual-fuel injector in the oil injection state in an embodiment of the present invention;

[0037] Figure 3 It is a cross-sectional view of the dual-fuel injector in the gas jet state in an embodiment of the present invention;

[0038] Figure 4 It is a cross-sectional view of the dual-fuel injector in the state of simultaneous oil and gas injection in an embodiment of the present invention;

[0039] Figure 5 It is a schematic structural view of the gas jet channel in an embodiment of the present invention;

[0040] Figure 6 It is a schematic diagram of the geometric parameters of the gas jet channel in an embodiment of the present invention;

[0041] Figure 7 It is a schematic diagram of the geometric parameters of the pressure stabilizing cavity in an embodiment of the present invention;

[0042] Figure 8 It is a schematic diagram of the gas flow path in the pressure stabilizing cavity in an embodiment of the present invention;

[0043] Figure 9 This is the relationship curve between the lift and the gas intake flow rate in the embodiments of the present invention.

[0044] In the figure:

[0045] 1. Fuel injection valve core; 2. Fuel injection valve seat; 3. Jet valve seat;

[0046] 10. Fuel injection holes; 20. Jet channels;

[0047] 21. Gas supply chamber; 22. Regulation chamber; 23. Voltage stabilization chamber; 24. Jet chamber; 241. Inlet section; 242. Acceleration section; 243. Injection section. Specific embodiments

[0048] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0049] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. 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 element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions, and the first feature being "above", "over" and "on" the second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature has a higher horizontal height than the second feature. The first feature being "below", "under" and "beneath" the second feature includes the first feature being directly below and obliquely below the second feature, or simply indicating that the first feature has a lower horizontal height than the second feature.

[0050] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0051] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where like or similar reference numerals denote like or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

[0052] As Figures 1-9As shown in the figure, the present invention provides a dual-fuel injector which is installed on the cylinder head of an engine and is used to inject fuel and / or gas into the combustion chamber. The dual-fuel injector includes an injection valve core 1, an injection valve seat 2 and a gas injection valve seat 3. The injection valve seat 2 is provided with an injection channel, and the injection valve core 1 is arranged in the injection channel. The injection valve core 1 can move relative to the injection valve seat 2 to open or close the injection channel. An injection hole 10 is provided on the injection valve seat 2. The injection hole 10 communicates with the injection channel and is used to inject fuel into the combustion chamber. The gas injection valve seat 3 is sleeved outside the injection valve seat 2, and a gas injection channel 20 is formed between the injection valve seat 2 and the gas injection valve seat 3. The injection valve seat 2 can move relative to the gas injection valve seat 3 to increase or decrease the width of the gas injection channel 20. The gas injection channel 20 includes a gas injection cavity 24 which is used to inject gas into the combustion chamber. Both the injection valve seat 2 and the gas injection valve seat 3 are of a cylindrical structure and are coaxially arranged. There is a gap between the outer side of the injection valve seat 2 and the inner side of the gas injection valve seat 3, and this gap is the gas injection channel 20. As the injection valve seat 2 moves relative to the gas injection valve seat 3, the local gap between the two increases or decreases, thereby realizing the increase or decrease of the width of the gas injection channel 20. The gas injection cavity 24 is located at the end close to the combustion chamber, so that the cross-section of the position where the gas sprays out from the gas injection channel 20 is annular, thereby realizing more uniform injection of the gas, and further enabling more uniform combustion. In addition, the axis of the injection hole 10 is arranged at an angle with the central axis of the dual-fuel injector; along the flow direction of the gas, the extending direction of the gas injection cavity 24 is parallel to the central axis or inclined towards the central axis. Making the extending direction of the gas injection cavity 24 parallel to the central axis of the dual-fuel injector or inclined towards the central axis enables more gas to be injected into the combustion chamber pit, improves the combustion speed, thereby avoiding deterioration of emissions while increasing the thermal efficiency. When the extending direction of the gas injection cavity 24 is inclined with the central axis, the included angle between the gas injection cavity 24 and the central axis is preferably less than or equal to 15°, so as to ensure that the wall thickness of the injection valve seat 2 meets the requirements of the injection pressure and the gas injection pressure. For the convenience of description and understanding, in this embodiment, the case where the extending direction of the gas injection cavity 24 is parallel to the central axis will be elaborated. The axis of the injection hole 10 is arranged at an angle with the central axis of the dual-fuel injector, so that the distance between the fuel and the gas is closer, and the fuel can ignite the gas faster, thereby realizing the improvement of the thermal efficiency. The dual-fuel injector in this embodiment can make the gas injected into the combustion chamber be as concentrated as possible and evenly distributed in the combustion chamber pit, shorten the distance between the fuel and the gas, realize faster ignition of the gas by the fuel, improve the combustion speed of the gas and ensure uniform combustion of the gas in the combustion chamber, thereby avoiding deterioration of emissions and reducing the vibration of the engine while increasing the thermal efficiency.

[0053] Further, as Figures 5-8As shown, the jet channel 20 is further provided with a gas supply chamber 21, an adjustment chamber 22 and a pressure stabilizing chamber 23. The gas supply chamber 21, the adjustment chamber 22, the pressure stabilizing chamber 23 and the jet chamber 24 are connected, and the gas supply chamber 21, the adjustment chamber 22, the pressure stabilizing chamber 23 and the jet chamber 24 are arranged in sequence along the flow direction of the fuel gas. The gas supply chamber 21 is used to communicate with the fuel gas tank. The width of the adjustment chamber 22 increases or decreases as the fuel injection valve seat 2 moves up and down relative to the jet valve seat 3. The increase or decrease of the width of the adjustment chamber 22 directly determines the amount of fuel gas flowing in the adjustment chamber 22, thereby determining the amount of fuel gas entering the pressure stabilizing chamber 23, and finally realizing the adjustment of the flow rate of the fuel gas ejected through the jet chamber 24.

[0054] Specifically, please refer to Figure 5 and in combination with Figure 6 As shown, let the width of the gas supply chamber 21 be D1, the width of the adjustment chamber 22 be D2, and the width of the jet chamber 24 be D3. It can be understood that the width of the adjustment chamber 22 changes with the movement of the fuel injection valve seat 2. Therefore, the value of D2 is variable, and its maximum value is the width corresponding to the fuel injection valve seat 2 moving to the upper limit position. Correspondingly, in this embodiment, the width of the gas supply chamber 21 is set to be greater than the maximum width of the adjustment chamber 22, that is, D1 > D2max, to ensure that the supply of fuel gas is not restricted by the width of the gas supply chamber 21. At the same time, the maximum width of the adjustment chamber 22 is greater than or equal to the width of the jet chamber 24, that is, D2max ≥ D3, to ensure that the fuel gas will not be decelerated by the jet chamber 24 after passing through the jet chamber 24, thereby ensuring the penetration distance of the fuel gas.

[0055] In addition, please continue to refer to Figure 5 and in combination with Figure 6 As shown, along the central axis direction of the dual fuel injector, the length of the jet chamber 24 is greater than the length of the pressure stabilizing chamber 23, and the length of the pressure stabilizing chamber 23 is greater than the length of the adjustment chamber 22. By setting the pressure stabilizing chamber 23, a buffer is provided between the adjustment chamber 22 and the jet chamber 24. When the width of the jet chamber 24 changes, the fuel gas flow rate changes accordingly. At this time, the pressure stabilizing chamber 23 can prevent the fuel gas in the adjustment chamber 22 from impacting the jet chamber 24 to ensure the stability of the fuel gas jet in the jet chamber 24 and reduce the fluctuations of pressure and flow rate. And setting the length of the jet chamber 24 to be greater than the length of the pressure stabilizing chamber 23 further ensures the flow state of the fuel gas after passing through the jet chamber 24 and further ensures the stability of the jet. At the same time, setting the length of the pressure stabilizing chamber 23 to be greater than the length of the adjustment chamber 22 is to provide enough buffer space for the fuel gas in the adjustment chamber 22 to enter the pressure stabilizing chamber 23 and further avoid impact.

[0056] Furthermore, as Figure 5As shown in the figure, along the flow direction of the fuel gas, an inlet section 241, an acceleration section 242, and a spraying section 243 are sequentially arranged in the jet cavity 24, and the inlet section 241, the acceleration section 242, and the spraying section 243 are sequentially connected end to end. The inlet section 241 has a flared structure, the large end of the inlet section 241 communicates with the pressure stabilizing cavity 23, and the acceleration section 242 communicates with the small end of the inlet section 241. The spraying section 243 is provided with a straight wall on one side of the jet valve seat 3 and an inclined wall on one side of the fuel injection valve seat 2, and is inclined toward the direction close to the central axis. A part of the fuel gas ejected from the spraying section 243 will move toward the direction close to the central axis under the guidance of the inclined wall, thereby further improving the concentration degree of the fuel gas in the combustion chamber pit. As Figure 6 shown in the figure, let the included angle between the inclined wall of the spraying section 243 on one side of the fuel injection valve seat 2 and the horizontal direction be γ, then γ is less than 60°. Within this range, the penetration distance of the fuel gas ejected from the spraying section 243 will not be significantly affected. As Figure 6 shown in the figure, along the central axis direction of the dual fuel injector, let the length of the adjustment cavity 22 be L1, the length of the pressure stabilizing cavity 23 be L2, the length of the inlet section 241 of the jet cavity 24 be L3, the length of the acceleration section 242 of the jet cavity 24 be L4, and the length of the spraying section 243 of the jet cavity 24 be L5. Then L4 > L2 > L1 > L5 ≥ L3. The inlet section 241, the acceleration section 242, and the spraying section 243 together form a Venturi structure, thereby accelerating the fuel gas to increase the penetration distance of the fuel gas. In this way, the width of the adjustment cavity 22 can be appropriately reduced and the penetration distance of the fuel gas can be ensured to meet the requirements. The width D2 of the adjustment cavity 22 depends on the distance that the fuel injection valve seat 2 moves relative to the jet valve seat 3, that is, the lift of the fuel injection valve seat 2. As Figure 6 shown in the figure, let the lift of the fuel injection valve seat 2 be H, and it is positively correlated with D2. The larger the lift H, the lower the control accuracy and response speed. Therefore, by setting the jet cavity 24 as a Venturi structure to accelerate the fuel gas, the penetration distance requirement of the ejected fuel gas can be met with a smaller lift, thereby improving the control accuracy and response speed.

[0057] Specifically, the pressure stabilizing cavity 23 is provided with a straight wall on one side of the fuel injection valve seat 2, the upper section on one side of the jet valve seat 3 is provided with a straight wall, the lower section is provided with an inclined wall, and extends downward to become the inclined wall of the inlet section 241 on one side of the jet valve seat 3. That is, the included angle between the inclined wall of the lower section of the pressure stabilizing cavity 23 on one side of the jet valve seat 3 and the horizontal direction is equal to the included angle between the inclined wall of the inlet section 241 of the jet cavity 24 on one side of the jet valve seat 3 and the horizontal direction. In this embodiment, let this included angle be β. As Figure 7As shown in the figure. Correspondingly, the included angle between the inclined wall on one side of the inlet section 241 of the jet cavity 24 and the horizontal direction is set as α, and α is greater than β, that is, the included angle between the inclined wall on one side of the inlet section 241 and the horizontal direction is greater than the included angle between the inclined wall on one side of the jet valve seat 3 and the horizontal direction. With such a setting, the process of the gas entering the jet cavity 24 from the pressure stabilizing cavity 23 is smoother. The flow path schematic diagram of the gas flowing from the regulating cavity 22 into the pressure stabilizing cavity 23 and then into the jet cavity 24 Figure 8 As shown. The included angle between the inclined wall on one side of the inlet section 241 and the horizontal direction is greater than or equal to 45° and less than or equal to 60°, that is Figure 7 the included angle α shown in the figure satisfies 45° ≤ α ≤ 60°. The included angle between the inclined wall on one side of the inlet section 241 and the horizontal direction of the jet valve seat 3 is greater than or equal to 45° and less than or equal to 60°, that is Figure 7 the included angle β shown in the figure satisfies 45° ≤ β ≤ 60°. Combining with α > β, then 45° ≤ β < α ≤ 60°. When the value of α and / or β is too small, the jet cavity 24 cannot effectively accelerate the gas; when the value of α and / or β is too large, it is easy to cause velocity shunting of the gas in the acceleration section 242 of the jet cavity 24, affecting the injection effect.

[0058] It has been verified that, compared with using a dual-fuel injector in the prior art, the indicated thermal efficiency of a dual-fuel engine using the dual-fuel injector in this embodiment is increased from 51.6% to 53.4%, and the methane emission is optimized from 0.018 g / kW·h to 0.006 g / kW·h.

[0059] The present invention provides a design method for a dual-fuel injector, which is used for the structural design of the dual-fuel injector in this embodiment. The design method of the dual-fuel injector includes the following steps:

[0060] Establish a simulation model of the dual-fuel injector;

[0061] Adjust the number and / or diameter of the fuel injection holes 10, and perform simulation on the simulation model to make the fuel penetration distance within a first preset range;

[0062] Adjust the width of the jet channel 20, and perform simulation on the simulation model to make the gas penetration distance within a second preset range;

[0063] Adjust the included angle between the axis of the fuel injection hole 10 and the central axis according to the ignition effect of the fuel on the gas.

[0064] It should be noted that the first preset range and the second preset range are determined according to the specific structure and size of the combustion chamber. During the design process, different first preset ranges and second preset ranges can be determined according to the combustion chambers of different models, and the first preset range and the second preset range are not specifically limited herein. The ignition effect of fuel on gas is evaluated by those skilled in the art according to actual engineering requirements and engine characteristics. The evaluation indicators include but are not limited to: fuel injection landing point, fuel compression ignition time, position and range of fuel igniting gas, etc. The selection of evaluation indicators and judgment conditions are all prior arts and will not be elaborated herein.

[0065] In the design method of the dual-fuel injector in this embodiment, by adjusting the number and diameter of the fuel injection holes 10, the fuel penetration distance is within the first preset range; by adjusting the width of the gas injection channel 20, the gas penetration distance is within the second preset range; and by adjusting the angle between the axis of the fuel injection hole 10 and the central axis, the fuel can ignite the gas faster, achieving an improvement in thermal efficiency. And by designing the dual-fuel injector through this method, it can be applied to combustion chambers with different structures and sizes.

[0066] Specifically, the method for adjusting the number and diameter of the fuel injection holes 10 includes the following steps:

[0067] Determine the first preset range according to the specific structure of the combustion chamber, and perform simulation on the dual-fuel injector;

[0068] When the fuel penetration distance is less than the minimum value of the first preset range, reduce the number of the fuel injection holes 10 and / or reduce the diameter of the fuel injection holes 10 until the fuel penetration distance is within the first preset range;

[0069] When the fuel penetration distance is greater than the maximum value of the first preset range, increase the number of the fuel injection holes 10 and / or increase the diameter of the fuel injection holes 10 until the fuel penetration distance is within the first preset range.

[0070] Specifically, the method for adjusting the width of the gas injection channel 20 includes the following steps:

[0071] Determine the second preset range according to the specific structure of the combustion chamber, and perform simulation on the dual-fuel injector;

[0072] When the gas penetration distance is less than the minimum value of the second preset range, reduce the width of the gas injection channel 20 until the gas penetration distance is within the second preset range;

[0073] When the gas penetration distance is greater than the maximum value of the second preset range, increase the width of the gas injection channel 20 until the gas penetration distance is within the second preset range.

[0074] It should be noted that in this embodiment, the width of the jet channel 20 is increased or decreased as a whole, and the widths of the air supply chamber 21, the pressure stabilizing chamber 23, and the jet chamber 24 are increased or decreased synchronously in proportion to avoid affecting other parameters while changing the fuel penetration distance. The width of the jet channel 20 is a structural parameter of the dual-fuel injector and does not change with the opening degree of the jet channel 20. In addition, it should be noted that since the jet chamber 24 includes an inlet section 241, an acceleration section 242, and a jet section 243, the main part thereof is the acceleration section 242, and it is also the acceleration section 242 that significantly affects the fuel penetration distance. Therefore, the change in the width of the jet chamber 24 is mainly the change in the width of the acceleration section 242, and the angles of the corresponding inlet section 241 and jet section 243 can be maintained unchanged or adjusted adaptively within a limited range to ensure a good jet state of the fuel gas.

[0075] Further, please refer to Figure 7 As shown, as the angle between the axis of the fuel injection hole 10 and the central axis increases, the distance between the fuel spray and the fuel gas spray decreases, so that the fuel gas can be ignited faster. During this process, the injection penetration distance of the fuel increases, and when the angle between the axis of the fuel injection hole 10 and the central axis increases to a certain extent, the fuel will be sprayed outside the combustion chamber pit, which will instead cause the ignition speed to slow down and incomplete combustion. Therefore, please refer to Figure 7 As shown, let the angle between the axis of the fuel injection hole 10 and the central axis be θ, then 10° ≤ θ ≤ 45°, that is, the adjustment range of the angle between the axis of the fuel injection hole 10 and the central axis is 10° - 45°, so as to meet combustion chambers of different structures and take into account both the penetration distance of the fuel and the distance between the fuel spray and the fuel gas spray.

[0076] The present invention provides a control method for a dual-fuel injector, which is applied to the dual-fuel injector in this embodiment to control the fuel injection and / or gas injection of the dual-fuel injector. The dual-fuel injector has four states, namely, a closed state, a fuel injection state, a gas injection state, and a state of simultaneous fuel and gas injection. When the dual-fuel injector is in the closed state, please refer to Figure 1 As shown, part of the fuel injection valve core 1 is in contact with the fuel injection valve seat 2, and the fuel injection channel is closed; part of the fuel injection valve seat 2 is in contact with the gas injection valve seat 3, and the jet channel 20 is closed, so that neither fuel nor gas is injected. This state is applicable to the control of other strokes of the engine except the intake stroke. The fuel injection state, the gas injection state, or the state of simultaneous fuel and gas injection of the dual-fuel injector are all applicable to the control of the engine intake stroke. When the dual-fuel injector is in the fuel injection state, please refer to Figure 2 As shown, a certain gap is maintained between the fuel injection valve core 1 and the fuel injection valve seat 2, and the fuel injection channel is opened; part of the fuel injection valve seat 2 is in contact with the gas injection valve seat 3, and the jet channel 20 is closed, so that only fuel is injected. At this time, it is applicable to the emergency operation of the engine after the fuel gas is exhausted. Similarly, when the dual-fuel injector is in the gas injection state, please refer to Figure 3As shown, a part of the fuel injection valve core 1 is in contact with the fuel injection valve seat 2, and the fuel injection channel is closed; there is a certain gap between the fuel injection valve seat 2 and the gas injection valve seat 3, and the gas injection channel 20 is opened, so that only gas is injected. At this time, it is applicable to the emergency operation of the engine after the fuel is exhausted. For the state of simultaneous fuel and gas injection as the normal operation of the dual-fuel injector, please refer to Figure 4 As shown, there is a certain gap between the fuel injection valve core 1 and the fuel injection valve seat 2, and the fuel injection channel is opened; there is a certain gap between the fuel injection valve seat 2 and the gas injection valve seat 3, and the gas injection channel 20 is opened, so that fuel and gas are injected simultaneously. Specifically, in the state of simultaneous fuel and gas injection, first, the dual-fuel injector is calibrated to obtain the calibration result of the distance that the fuel injection valve seat 2 moves relative to the gas injection valve seat 3 and the gas flow rate; that is, the corresponding relationship between the fuel injection valve seat 2 and the gas flow rate at different lift heights is obtained, such as a relationship curve or a relationship table, etc.

[0077] The injection control method of the dual-fuel injector includes the following steps:

[0078] Calculate the required gas flow rate according to the required gas intake and the engine speed; the required gas intake is the total amount of gas supply required by the engine under the current working condition, and this value is calculated by the engine control unit and will not be described in detail here. The opening time of the gas injection channel 20 can be determined by the engine speed, so that the required gas flow rate can be obtained through the total amount of gas supply required and the opening time of the gas injection channel 20. In this process, compensation can be made in the design of the valve timing according to the response time of the opening and closing of the gas injection channel 20 to ensure the accuracy of the final injection volume.

[0079] Determine the distance that the fuel injection valve seat 2 of the dual-fuel injector moves relative to the gas injection valve seat 3 according to the corresponding relationship between the distance that the fuel injection valve seat 2 moves relative to the gas injection valve seat 3 and the gas flow rate, that is, determine the lift height of the fuel injection valve seat 2.

[0080] In this embodiment, the relationship curve between the lift height of the fuel injection valve seat 2 and the gas flow rate is as Figure 9 shown, where the abscissa is the lift height of the fuel injection valve seat 2 and the ordinate is the gas injection flow rate. Since the width of the adjustment chamber 22 is determined by the lifting of the fuel injection valve seat 2 relative to the gas injection valve seat 3, the closing and opening of the gas injection channel 20 are realized through the fitting and separation of the inclined surface structure. When the lift height of the fuel injection valve seat 2 is small, the width of the adjustment chamber 22 is small. At this time, due to the setting of the inclined surface structure and the pressure stabilizing chamber 23, the obstruction to the gas flow is obvious. Therefore, in this stage, as the opening of the fuel injection valve seat 2 increases, the increase in the gas flow rate is not obvious. For details, please refer to Figure 9 the 0-1 / 6H stage of the curve in. As the opening of the fuel injection valve seat 2 increases, the width of the adjustment chamber 22 increases synchronously. At this time, the obstruction of the inclined surface structure and the pressure stabilizing chamber 23 to the gas flow decreases. Therefore, as the opening of the fuel injection valve seat 2 increases, the increasing speed of the gas flow rate gradually rises, that is, Figure 9The slope of the curve in the 1 / 6H - 1 / 3H stage of the middle curve gradually increases. The opening of the fuel injection valve seat 2 continues to increase, and the width of the regulating chamber 22 increases synchronously. At this time, the obstructive effect of the inclined plane structure and the pressure stabilizing chamber 23 on the gas flow is relatively weak, and the gas flow rate is positively correlated with the opening of the fuel injection valve seat 2, that is Figure 9 in the 1 / 3H - 3 / 4H stage of the middle curve, and basically can meet the gas flow requirements under various working conditions in this stage, and it is convenient to linearly control the fuel injection valve seat 2. The linear control range of the dual-fuel injector in this embodiment is wide, including a large gas flow range, which helps to more accurately control the gas flow rate. Finally, as the opening of the fuel injection valve seat 2 further increases, it will no longer be positively correlated with the gas flow rate at this time. Instead, while slowly increasing the gas flow rate, the pressure in the pressure stabilizing chamber 23 is increased, and finally the speed of the gas at the injection section 243 of the jet chamber 24 is increased, so that it can enter the combustion chamber faster. This stage is applicable to extreme working conditions such as sudden acceleration, ensuring that the gas is quickly ejected in a short time and improving the power response speed of the engine under sudden acceleration conditions.

[0081] The injection control method of the dual-fuel injector in this embodiment calibrates the dual-fuel injector, calculates the required gas flow rate according to the required gas intake and the engine speed, and determines the lift of the fuel injection valve seat 2 according to the calibration result, so that the injection response when injecting gas is faster and the injection control accuracy is higher.

[0082] Obviously, the above embodiments of the present invention are only examples for clearly explaining the present invention, and are not intended to limit the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made on the basis of the above description. It is not necessary and impossible to list all the implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. Dual fuel injector, characterized in that, It comprises an injection valve core (1), an injection valve seat (2) and an air injection valve seat (3); The fuel injection valve seat (2) is provided with a fuel injection channel, the fuel injection valve core (1) is located in the fuel injection channel, the fuel injection valve core (1) can move relative to the fuel injection valve seat (2) to open or close the fuel injection channel, and the fuel injection valve seat (2) is provided with a fuel injection hole (10), the fuel injection hole (10) is connected to the fuel injection channel and is used to inject fuel into the combustion chamber; The jet valve seat (3) is sleeved outside the fuel injection valve seat (2); an jet passage (20) is formed between the fuel injection valve seat (2) and the jet valve seat (3); the jet passage (20) comprises an air supply chamber (21), an adjusting chamber (22), a pressure stabilizing chamber (23) and an jet chamber (24); the air supply chamber (21), the adjusting chamber (22), the pressure stabilizing chamber (23) and the jet chamber (24) are connected; the air supply chamber (21), the adjusting chamber (22), the pressure stabilizing chamber (23) and the jet chamber (24) are arranged in sequence along the flow direction of the fuel gas; the opening of the adjusting chamber (22) increases or decreases as the fuel injection valve seat (2) rises or falls relative to the jet valve seat (3); the jet chamber (24) is used for injecting fuel gas into the combustion chamber; The axis of the fuel injection hole (10) is arranged at an angle to the central axis of the dual-fuel injector, and along the flow direction of the fuel gas, the extension direction of the injection cavity (24) is parallel to the central axis or inclined toward the central axis; The maximum width of the regulating chamber (22) is greater than or equal to the width of the jet chamber (24); along the direction of the central axis, the length of the jet chamber (24) is greater than the length of the pressure stabilizing chamber (23); and the length of the pressure stabilizing chamber (23) is greater than the length of the regulating chamber (22); Along the flow direction of the fuel gas, the jet chamber (24) is sequentially provided with an inlet section (241), an acceleration section (242) and an injection section (243); the inlet section (241) is a bell-mouth structure; the large end of the inlet section (241) is connected to the pressure stabilizing chamber (23); the acceleration section (242) is connected to the small end of the inlet section (241); the injection section (243) is arranged as a straight wall on one side of the jet valve seat (3) and as an inclined wall on one side of the fuel injection valve seat (2); the inclined wall is inclined in a direction close to the central axis.

2. The dual fuel injector according to claim 1, characterized in that: The angle between the inclined wall of the injection section (243) located on one side of the fuel injection valve seat (2) and the horizontal direction is less than 60 degrees.

3. The dual fuel injector according to claim 1, characterized in that The pressure stabilizing chamber (23) is located on one side of the fuel injection valve seat (2) and is configured as a straight wall. The upper section of the pressure stabilizing chamber (23) is located on one side of the jet valve seat (3) and is configured as a straight wall. The lower section is configured as an inclined wall and extends downward to form an inclined wall of the inlet section (241) located on one side of the fuel injection valve seat (3). The angle between the inclined wall of the inlet section (241) located on one side of the fuel injection valve seat (2) and the horizontal direction is greater than the angle between the inclined wall located on one side of the jet valve seat (3) and the horizontal direction.

4. The dual fuel injector according to claim 2, characterized in that The angle between the inclined wall of the inlet section (241) located on one side of the fuel injection valve seat (2) and the horizontal direction is greater than or equal to 45° and less than or equal to 60°, and the angle between the inclined wall of the inlet section (241) located on one side of the jet valve seat (3) and the horizontal direction is greater than or equal to 45° and less than or equal to 60°.

5. A design method for a dual fuel injector, characterized in that: For structural design of the dual-fuel injector according to any one of claims 1 to 4, the design method of the dual-fuel injector comprises: Build a simulation model of dual fuel injectors; Adjusting the number and / or diameter of the fuel injection holes (10) so that the fuel penetration distance is within a first preset range; Adjusting the width of the jet channel (20) so that the gas penetration distance is within a second preset range; The angle between the axis of the oil injection hole (10) and the central axis is adjusted according to the ignition effect of the oil on the gas.

6. The design method of a dual fuel injector according to claim 5, characterized in that: The method for adjusting the number and diameter of the oil injection holes (10) includes: When the fuel penetration distance is less than the minimum value of the first preset range, reducing the number of the fuel injection holes (10) and / or reducing the diameter of the fuel injection holes (10) until the fuel penetration distance is within the first preset range; When the fuel penetration distance is greater than a maximum value of the first preset range, increasing the number of fuel injection holes (10) and / or increasing the diameter of the fuel injection holes (10) until the fuel penetration distance is within the first preset range; The method for adjusting the width of the jet channel (20) comprises: When the gas penetration distance is less than the minimum value of the second preset range, reducing the width of the jet passage (20) until the gas penetration distance is within the second preset range; When the gas penetration distance is greater than the maximum value of the second preset range, the width of the jet channel (20) is increased until the gas penetration distance is within the second preset range.

7. The design method of a dual fuel injector according to claim 5, characterized in that: The adjustment range of the angle between the axis of the oil injection hole (10) and the central axis is 10°-45°.

8. A method for controlling injection of a dual fuel injector, characterized in that: Applied to the dual-fuel injector according to any one of claims 1 to 4, the injection control method of the dual-fuel injector comprises: Calculate the required gas flow rate based on the required gas intake volume and engine speed; The distance that the fuel injection valve seat (2) moves relative to the jet valve seat (3) is determined based on the corresponding relationship between the distance that the fuel injection valve seat (2) of the dual fuel injector moves relative to the jet valve seat (3) and the gas flow rate.

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