Dual fuel injector, design method thereof, and injection control method

Abstract

The invention relates to the technical field of engines, and particularly discloses a dual-fuel injector and a design method and an injection control method thereof, the dual-fuel injector forms a gas injection channel through a gas injection valve seat and a gas injection valve seat to directly inject fuel gas into a combustion chamber, the fuel gas injection is more uniform, and the fuel gas injection efficiency is improved. The extending direction of the gas injection cavity of the gas injection channel is parallel to the central axis of the dual-fuel injector or inclines towards the central axis, so that more gas is injected into a pit of a combustion chamber, the combustion speed is increased, and emission deterioration is avoided while the heat efficiency is improved; fuel oil can be used for igniting fuel gas more quickly, and the heat efficiency is improved.

Description

Technical Field

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

[0002] Existing dual-fuel engines usually use a dual-injector solution, in which one injector is used to inject fuel and the other injector is used to inject gas. The fuel ignites the gas for combustion, thereby achieving energy conservation and emission reduction. However, the injection control of the dual injectors is not easy to synchronize, so it is impossible to achieve a good injection and mixing effect. In this regard, the prior art provides a dual-fuel injector that integrates the functions of fuel injection and gas injection on the same injector to ensure synchronous injection. However, the structures of the existing dual-fuel injectors for fuel injection and gas injection are both multi-hole injection, and the directions of the injected oil beam and gas beam are parallel, which will cause most of the injected gas to be injected at the edge of the combustion chamber. The corresponding oil-gas mixture cloud diagram is shown in the figure. Figure 1 As shown in the figure, after the dual fuel injector is injected, the fuel and gas are mixed in the combustion chamber as the crankshaft rotates, but the mixed fuel is relatively dispersed in the combustion chamber, and the fuel concentrated in the pit of the combustion chamber is less, the combustion speed is slow, resulting in reduced thermal efficiency and worse emissions. In addition, since the oil beam and the gas beam are injected in parallel, the distance between them is far, the ignition effect of the fuel on the gas is poor, and the thermal efficiency is reduced. Summary of the invention

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

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

[0005] The fuel injection valve seat is provided with a fuel injection channel, the fuel injection valve core is located in the fuel injection channel, the fuel injection valve core can move relative to the fuel injection valve seat to open or close the fuel injection channel, and the fuel injection valve seat is provided with a fuel injection hole, the fuel injection hole is connected with the fuel injection channel and is used to inject fuel into the combustion chamber;

[0006] The jet valve seat is sleeved outside the fuel injection valve seat, and an jet passage is formed between the fuel injection valve seat and the jet valve seat, and the jet passage includes an adjustment chamber and an injection chamber, and the opening of the adjustment chamber increases and decreases as the fuel injection valve seat rises and falls relative to the jet valve seat, and the injection chamber is used to inject fuel gas into the combustion chamber;

[0007] The axis of the fuel injection hole is arranged at an angle with the central axis of the dual-fuel injector, and along the flow direction of the fuel gas, the extension direction of the injection cavity is parallel to the central axis or inclined toward the central axis.

[0008] As a preferred technical solution of the dual-fuel injector, the injection channel further includes a pressure stabilizing chamber, and the regulating chamber and the injection chamber are connected through the pressure stabilizing chamber.

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

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

[0011] As a preferred technical solution for a dual-fuel injector, along the flow direction of the fuel gas, the injection chamber is sequentially provided with an inlet section, an acceleration section and an injection section, the inlet section is a bell-mouth structure, the large end of the inlet section is connected to the pressure stabilizing chamber, the acceleration section is connected to the small end of the inlet section, the injection section is located on a side of the injection valve seat and is configured as a straight wall, and is located on a side of the injection valve seat and is configured as an inclined wall, and the inclined wall is inclined toward a direction close to the central axis.

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

[0013] As a preferred technical solution for the dual-fuel injector, the pressure-stabilizing chamber is located on a side of the injection valve seat and is configured as a straight wall, the upper section of the pressure-stabilizing chamber is located on a side of the injection valve seat and is configured as a straight wall, and the lower section is configured as an inclined wall and extends downward to form an inclined wall of the inlet section on the side of the injection valve seat, and the angle between the inclined wall of the inlet section on the side of the injection valve seat and the horizontal direction is greater than the angle between the inclined wall on the side of the injection valve seat and the horizontal direction.

[0014] As a preferred technical solution for the dual-fuel injector, the angle between the inclined wall of the inlet section located on one side of the injection valve seat 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 located on one side of the injection 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 dual-fuel injector design method, which is used to perform structural design on a dual-fuel injector of any of the above schemes. The dual-fuel injector design method comprises:

[0016] Establish a simulation model of dual fuel injectors;

[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 jet channel so that the gas penetration distance is within the second preset range;

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

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

[0021] Methods for adjusting the number and diameter of injection holes include:

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

[0024] Methods for adjusting the width of the jet channel include:

[0025] When the gas penetration distance is less than the minimum value of the second preset range, reducing the width of the jet passage 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, the width of the jet passage is increased until the gas penetration distance is within the second preset range.

[0027] As a preferred technical solution for the design method of the dual-fuel injector, the adjustment range of the angle between the axis of the 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 scheme. The injection control method for the dual-fuel injector comprises:

[0029] Calculate the required gas flow rate based on the required gas intake volume and engine speed;

[0030] The distance that the fuel injection valve seat moves relative to the jet valve seat of the dual fuel injector is determined according to the corresponding relationship between the distance that the fuel injection valve seat moves relative to the jet valve seat and the gas flow rate.

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

[0032] The present invention provides a dual-fuel injector, which directly injects fuel gas into a combustion chamber by forming a jet channel through an injection valve seat and an air jet valve seat. The fuel gas is injected more evenly, and the extension direction of the jet cavity of the jet channel is parallel to the central axis of the dual-fuel injector or inclined toward the central axis, so that more fuel gas is injected into the pit of the combustion chamber, thereby increasing the combustion speed, thereby improving the thermal efficiency while avoiding emission deterioration, and the axis of the fuel injection hole is arranged at an angle to the central axis, which can realize faster ignition of fuel gas by fuel, thereby improving thermal efficiency.

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

[0034] The present invention provides an injection control method for a dual-fuel injector, which calculates the required gas flow rate according to the required gas intake amount and the engine speed, and determines the opening of the injection channel, so that the injection response when injecting the gas is faster and the injection control accuracy is higher. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0037] Figure 3 is a cross-sectional view of a dual-fuel injector in an injection state according to an embodiment of the present invention;

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

[0039] Figure 5 Schematic diagram of the structure of the jet channel in an embodiment of the present invention;

[0040] Figure 6 Schematic diagram of geometric parameters of the jet channel in an embodiment of the present invention;

[0041] Figure 7 Schematic diagram of geometric parameters of the pressure stabilizing cavity in an embodiment of the present invention;

[0042] Figure 8 Schematic diagram of the gas flow path in the pressure stabilizing chamber in an embodiment of the present invention;

[0043] Fig. 9 : is a curve showing the relationship between lift and fuel gas intake flow rate in an embodiment of the present invention.

[0044] In the figure:

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

[0046] 10. Oil injection hole; 20. Injection channel;

[0047] 21. Air supply chamber; 22. Adjustment chamber; 23. Pressure stabilization chamber; 24. Jet chamber; 241. Inlet section; 242. Acceleration section; 243. Jet section. DETAILED DESCRIPTION

[0048] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] In the description of the present invention, it should be noted that the orientations or positional relationships indicated by the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. 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, 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 cannot be understood as limiting 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 "above", "above" and "above" the second feature include the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. The first feature "below", "below" and "below" the second feature include the first feature being directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0050] In the description of the present invention, it should be noted that, unless otherwise clearly specified 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 a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0052] like Figure 1-Figure 9As shown, the present invention provides a dual fuel injector, which is installed on the cylinder head of the 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 an injection valve seat 3. The injection valve seat 2 is provided with an injection channel, 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, and the injection valve seat 2 is provided with an injection hole 10, which is connected to the injection channel and is used to inject fuel into the combustion chamber. The injection valve seat 3 is sleeved outside the injection valve seat 2, and an injection channel 20 is formed between the injection valve seat 2 and the injection valve seat 3. The injection valve seat 2 can move relative to the injection valve seat 3 to increase or decrease the width of the injection channel 20. The injection channel 20 includes an injection cavity 24, and the injection cavity 24 is used to inject gas into the combustion chamber. The fuel injection valve seat 2 and the jet valve seat 3 are both cylindrical structures, and the two are coaxially arranged. There is a gap between the outer side of the fuel injection valve seat 2 and the inner side of the jet valve seat 3, which is the jet channel 20. As the fuel injection valve seat 2 moves relative to the jet valve seat 3, the local gap between the two increases or decreases, thereby increasing or decreasing the width of the jet channel 20. The jet cavity 24 is located at one end close to the combustion chamber, so that the cross section of the position where the gas is ejected from the jet channel 20 is annular, thereby achieving more uniform injection of the gas, and then more uniform combustion. In addition, the axis of the fuel injection hole 10 is set at an angle with the central axis of the dual-fuel injector; along the flow direction of the gas, the extension direction of the jet cavity 24 is parallel to the central axis or inclined toward the central axis. The extension direction of the jet cavity 24 is parallel to the central axis of the dual-fuel injector or inclined toward the central axis, so that more gas is injected into the combustion chamber pit, the combustion speed is increased, and the thermal efficiency is improved while avoiding emission deterioration. When the extension direction of the jet chamber 24 is inclined with the central axis, the angle between the jet chamber 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 jet pressure. For the convenience of description and understanding, the present embodiment will be carried out based on the situation that the extension direction of the jet chamber 24 is arranged parallel to the central axis. The axis of the jet hole 10 is arranged at an angle with the central axis of the dual-fuel injector, and the distance between the fuel and the gas is closer, which can realize the ignition of the fuel to the gas faster, thereby realizing the improvement of thermal efficiency. The dual-fuel injector in this embodiment can make the gas injected into the combustion chamber as concentrated as possible and evenly distributed in the combustion chamber pit, and shorten the distance between the fuel and the gas, realize the faster ignition of the fuel to the gas, increase the combustion speed of the gas and ensure the uniform combustion of the gas in the combustion chamber, thereby improving the thermal efficiency while avoiding emission deterioration and reducing the vibration of the engine.

[0053] Furthermore, if Figure 5-Figure 8As shown, the jet channel 20 is also provided with an air supply chamber 21, an adjusting chamber 22 and a pressure stabilizing chamber 23. The air supply chamber 21, the adjusting chamber 22, the pressure stabilizing chamber 23 and the jet chamber 24 are connected, and 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 gas. The air supply chamber 21 is used to communicate with the gas tank, and the width of the adjusting chamber 22 increases or decreases as the injection valve seat 2 rises or falls relative to the injection valve seat 3. The increase or decrease in the width of the adjusting chamber 22 directly determines the size of the gas flow in the adjusting chamber 22, thereby determining the amount of gas entering the pressure stabilizing chamber 23, and finally realizing the adjustment of the flow of the gas ejected through the jet chamber 24.

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

[0055] In addition, please continue to refer to Figure 5 Combined with Figure 6 As shown, along the central axis 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 regulating chamber 22. By setting the pressure stabilizing chamber 23, a buffer is provided between the regulating chamber 22 and the jet chamber 24. When the width of the jet chamber 24 changes, the gas flow rate changes accordingly. At this time, the pressure stabilizing chamber 23 can prevent the gas in the regulating chamber 22 from impacting the jet chamber 24, so as to ensure the stability of the jet of the jet chamber 24 and reduce the fluctuation of pressure and flow rate. 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 gas after it flows 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 regulating chamber 22 is to provide the pressure stabilizing chamber 23 with sufficient buffer space for the gas in the regulating chamber 22 after it enters the pressure stabilizing chamber 23, so as to further avoid impact.

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

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

[0058] It has been verified that, compared with the dual-fuel injector used in the prior art, the indicated thermal efficiency of the dual-fuel engine using the dual-fuel injector in this embodiment is improved 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 dual-fuel injector design method, which is used to perform structural design on the dual-fuel injector in this embodiment. The dual-fuel injector design method includes the following steps:

[0060] Establish a simulation model of dual fuel injectors;

[0061] Adjust the number and / or diameter of the fuel injection holes 10 and simulate the simulation model so that the fuel penetration distance is within a first preset range;

[0062] Adjust the width of the jet channel 20 and simulate the simulation model so that the gas penetration distance is within a second preset range;

[0063] The angle between the axis of the fuel injection hole 10 and the central axis is adjusted 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. Different first preset ranges and second preset ranges can be determined according to the combustion chambers of different models during the design process. The first preset range and the second preset range are not specifically limited here. 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 point, fuel compression ignition time, fuel ignition gas position and range, etc. The selection of evaluation indicators and judgment conditions are all existing technologies and will not be repeated here.

[0065] The design method of the dual-fuel injector in this embodiment adjusts the number and diameter of the fuel injection holes 10 so that the fuel penetration distance is within the first preset range; adjusts the width of the jet channel 20 so that the gas penetration distance is within the second preset range; and adjusts the angle between the axis of the fuel injection hole 10 and the central axis so that the fuel can ignite the gas faster and improve the thermal efficiency. And the dual-fuel injector is designed by this method so that it can be applied to combustion chambers of different structures and sizes.

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

[0067] Determining a first preset range according to a specific structure of the combustion chamber, and simulating the dual-fuel injector;

[0068] 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;

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

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

[0071] Determining a second preset range according to a specific structure of the combustion chamber, and simulating the dual-fuel injector;

[0072] When the gas penetration distance is less than the minimum value of the second preset range, the width of the jet passage 20 is reduced 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, the width of the jet passage 20 is increased 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 gas penetration distance. The width of the jet channel 20 is a structural parameter of the dual-fuel injector, which does not change with the opening 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 an injection section 243, the main part of the jet chamber 24 is the acceleration section 242, and it is the acceleration section 242 that has a significant impact on the gas penetration distance, the change in the width of the jet chamber 24 is mainly the change in the width of the acceleration section 242, and the corresponding angles of the inlet section 241 and the injection section 243 can be maintained unchanged, or can be adaptively adjusted within a limited range to ensure a good injection state of the gas.

[0075] For further information, please refer to Figure 7 As shown in the figure, as the angle between the axis of the injection hole 10 and the central axis increases, the distance between the fuel beam and the gas beam decreases, so that the gas can be ignited faster. In this process, the injection penetration distance of the fuel increases, and when the angle between the axis of the injection hole 10 and the central axis increases to a certain extent, the fuel will be sprayed outside the combustion chamber pit, which will slow down the ignition speed and incomplete combustion. Therefore, please refer to Figure 7 As shown, assuming that the angle between the axis of the injection hole 10 and the central axis is θ, then 10°≤θ≤45°, that is, the adjustment range of the angle between the axis of the injection hole 10 and the central axis is 10°-45°, thereby satisfying combustion chambers of different structures while taking into account the penetration distance of the fuel and the distance between the fuel beam and the gas beam.

[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 air injection of the dual fuel injector. The dual fuel injector has four states, namely, a closed state, a fuel injection state, an air injection state, and a simultaneous fuel and air injection state. When the dual fuel injector is in the closed state, refer to Figure 1 As shown, the fuel injection valve core 1 is partially fitted with the fuel injection valve seat 2, and the fuel injection channel is closed; the fuel injection valve seat 2 is partially fitted with the jet valve seat 3, and the jet channel 20 is closed, so that neither fuel oil nor gas is injected. This state is suitable for controlling other strokes of the engine except the intake stroke. The dual-fuel injector is in the fuel injection state, the jet state, or the simultaneous fuel and gas injection state, which is suitable for controlling the intake stroke of the engine. When the dual-fuel injector is in the fuel injection state, refer to Figure 2 As shown, the fuel injection valve core 1 and the fuel injection valve seat 2 maintain a certain gap, and the fuel injection channel is open; the fuel injection valve seat 2 and the jet valve seat 3 are partially fitted, and the jet channel 20 is closed, so that only fuel is injected. This is suitable for emergency operation of the engine after the gas is exhausted. Similarly, when the dual-fuel injector is in the injection state, refer to Figure 3As shown, the injection valve core 1 is partially fitted with the injection valve seat 2, and the injection channel is closed; the injection valve seat 2 and the jet valve seat 3 maintain a certain gap, and the jet channel 20 is open, so that only fuel gas is injected. This is suitable for emergency operation of the engine after the fuel is exhausted. The simultaneous injection of fuel and gas is the normal working state of the dual fuel injector, please refer to Figure 4 As shown, the fuel injection valve core 1 and the fuel injection valve seat 2 maintain a certain gap, and the fuel injection channel is open; the fuel injection valve seat 2 and the jet valve seat 3 maintain a certain gap, and the jet channel 20 is open, so that the fuel and the gas are injected at the same time. Specifically, in the state of simultaneous injection of oil and gas, the dual-fuel injector is first calibrated to obtain the calibration results of the distance of the fuel injection valve seat 2 moving relative to the jet 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 lifts is obtained, such as a relationship curve or a relationship table.

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

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

[0079] According to the correspondence 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, 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 is determined.

[0080] The relationship curve between the lift of the injection valve seat 2 and the gas flow rate in this embodiment is as follows: Fig. 9 As shown, the horizontal axis is the lift of the fuel injection valve seat 2, and the vertical axis is the jet flow rate. Since the width of the regulating chamber 22 is determined by the lift of the fuel injection valve seat 2 relative to the jet valve seat 3, the two realize the closing and opening of the jet channel 20 through the fitting and separation of the inclined surface structure. When the lift of the fuel injection valve seat 2 is small, the width of the regulating chamber 22 is small. At this time, due to the setting of the inclined surface structure and the pressure stabilizing chamber 23, the gas flow is significantly hindered. Therefore, at this stage, as the opening of the fuel injection valve seat 2 increases, the increase in gas flow is not obvious. For details, please refer to Fig. 9 The 0-1 / 6H stage of the middle curve. As the opening of the injection valve seat 2 increases, the width of the regulating chamber 22 increases synchronously. At this time, the obstruction of the inclined surface structure and the pressure stabilizing chamber 23 to the gas flow is reduced. Therefore, as the opening of the injection valve seat 2 increases, the gas flow rate increases gradually, that is, Fig. 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 obstruction effect of the inclined surface 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, Fig. 9 The 1 / 3H-3 / 4H stage of the middle curve, and in this stage it can basically meet the gas flow requirements under various working conditions, and it is convenient to linearly control the injection valve seat 2. The dual-fuel injector in this embodiment has a wide linear control range, including a large gas flow range, which helps to more accurately control the gas flow. Finally, as the opening of the injection valve seat 2 further increases, it will no longer be positively correlated with the gas flow, but while slowly increasing the gas flow, it will increase the pressure in the pressure stabilizing chamber 23, and finally increase the speed of the gas at the injection section 243 of the injection chamber 24, so that it enters the combustion chamber faster. This stage is suitable for extreme working conditions such as rapid acceleration, ensuring that the gas is quickly ejected in a short time, and improving the power response speed of the engine under rapid 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 amount and the engine speed, and adjusts the lift of the 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 merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should 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), and an jet passage (20) is formed between the fuel injection valve seat (2) and the jet valve seat (3). The jet passage (20) includes an adjustment chamber (22) and an injection chamber (24). The opening of the adjustment chamber (22) increases or decreases as the fuel injection valve seat (2) rises or falls relative to the jet valve seat (3), and the injection chamber (24) is used to inject fuel gas into the combustion chamber. The axis of the fuel injection hole (10) is arranged at an angle with 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.

2. The dual fuel injector according to claim 1, characterized in that: The jet passage (20) further comprises a pressure stabilizing chamber (23), and the regulating chamber (22) and the jet chamber (24) are connected via the pressure stabilizing chamber (23).

3. The dual fuel injector according to claim 2, characterized in that: The maximum width of the regulating chamber (22) is greater than or equal to the width of the jet chamber (24).

4. The dual fuel injector according to claim 2, characterized in that 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).

5. The dual fuel injector according to claim 2, characterized in that 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.

6. The dual fuel injector according to claim 5, 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.

7. The dual fuel injector according to claim 5, 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.

8. The dual fuel injector according to claim 7, 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°.

9. 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 8, 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.

10. The design method of a dual fuel injector according to claim 9, 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.

11. The design method of a dual fuel injector according to claim 9, 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°.

12. 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 8, 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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