Dual-fuel oil injector

Abstract

The utility model belongs to the technical field of internal combustion engine electric control, and particularly relates to a dual-fuel oil injector. A dual-fuel oil injector sequentially comprises an injector body, a needle valve body, a first fuel channel section A, a first fuel channel section D located on the center line of the needle valve, an oil inlet throttling hole connected between the section A and the section D in series, a second fuel channel section D formed by a gap between the needle valve and the needle valve body, a plurality of distribution holes located in the lower portion of the needle valve and a pressure storage cavity from bottom to top. And a second fuel one-way valve. Compared with the prior art, the fuel injector has the advantages that control over the injection amount of two kinds of fuel can be achieved only through one control valve, liquid path arrangement is compact, the mechanism is simple, and the fuel injector is small in size, high in reliability, low in cost and easy to apply to engineering.

Description

Technical Field

[0001] This patent belongs to the technical field of internal combustion engine electronic control, and specifically relates to a common rail type dual fuel injector for compression ignition internal combustion engines. Background Art

[0002] In the field of internal combustion engine fuel applications, sometimes it is necessary to inject two fuels with different physical and chemical properties into the cylinder. For example, in a compression ignition engine, a fuel with a higher cetane number, such as diesel or biodiesel, is first injected, and then a fuel with a lower cetane number, such as methanol, ethanol, liquid ammonia, high-pressure natural gas, or high-pressure hydrogen, is injected. A relatively simple method is to use two injectors to inject the two fuels respectively, but its installation processability is poor, and it is difficult for small and medium-sized internal combustion engines to find positions to install two injectors. The literature (CN103814208A) discloses a dual fuel injection valve for injecting diesel and natural gas, which is characterized by using a second movable needle inside the main needle, arranged coaxially, to achieve independent control and injection of two fuel paths, called HPDI technology. However, this solution has a very complex mechanism, a large injector volume, poor reliability, and high costs. Therefore, how to propose a dual fuel injector that is compatible with the existing installation method of common rail injectors, and has a simple mechanism, high reliability, and low cost has become an urgent need. Summary of the Invention

[0003] This patent proposes a dual fuel injector with a simple structure and high reliability. The specific technical solutions are as follows:

[0004] A dual fuel injector, which sequentially includes from bottom to top: an injector body, an electromagnet assembly, a tightening cap connected to the lower end of the injector body, a needle valve body located inside the tightening cap, and a needle valve located inside the needle valve body; the injector body includes a middle hole, and a tappet needle valve assembly is arranged inside the middle hole; it also includes:

[0005] The first fuel passage A section, the first fuel passage D section located on the needle valve center line, and an inlet throttle hole connected in series between the first fuel passage A section and the first fuel passage D section;

[0006] A check valve, the second fuel passage D section formed by the gap between the needle valve and the needle valve body;

[0007] An oil storage gap, which is around the head of the needle valve and above the sealing ring belt. The upstream of the oil storage gap is connected to the check valve through the second fuel passage D section;

[0008] Several dispersion holes located at the lower part of the needle valve, whose inner ports are connected to the lower part of the first fuel passage D section, and whose outer ports are connected to the lower part of the oil storage gap.

[0009] The control process is divided into the following steps:

[0010] Step 1: After the electromagnet is powered on, the tappet is lifted under control;

[0011] Step 2: The tappet drives the needle valve to rise and follow;

[0012] Step 3: After the electromagnet is powered off, the tappet drives the needle valve to move downward, and finally the needle valve seats; when the needle valve is in the seated state, the fuel supply pressure of the first fuel is greater than that of the second fuel. The first fuel sequentially passes through the A section of the first fuel passage, the inlet throttle orifice, the D section of the first fuel passage, and the dispersion orifice, and enters the oil storage gap; during this process, the second fuel originally existing in the oil storage gap is compressed and retreated by the first fuel coming out of the dispersion orifice, and moves along the D section of the second fuel passage and finally reaches the check valve. Due to the existence of the check valve, the second fuel will not flow back, so the pressure of the second fuel will rise. When the pressures of the two are equal, the first fuel stops flowing out of the first fuel dispersion orifice, and the fuel accumulation process of the first fuel in the body ends; at this time, the stored amount of the first fuel in the oil storage gap is proportional to the pressure difference ⊿P between the first fuel and the second fuel, and the total pressure accumulation volume V including the oil storage gap and the D section of the second fuel passage, and is also inversely proportional to the elastic modulus of the second fuel;

[0013] Step 4: After the fuel accumulation process of the first fuel ends, the needle valve is lifted under control. The first fuel in the oil storage gap enters the pressure chamber under the action of its own storage pressure and the pressure of the second fuel, and finally sprays out from the injection hole; when the first fuel is nearly completely injected, the needle valve is controlled to seat, and the pre-injection of the first fuel ends;

[0014] Step 5: After a short pause, the needle valve is lifted under control again. At this time, the amount of the first fuel in the oil storage gap is nearly zero. The second fuel sequentially passes through the check valve, the D section of the second fuel passage, the oil storage gap, the pressure chamber, and finally sprays out from the injection hole, starting the main injection process mainly with the second fuel;

[0015] Step 6: Then the needle valve is controlled to seat, and the injection process of the second fuel ends; the injection amount of the second fuel depends on the injection duration T and the fuel supply pressure P of the second fuel.

[0016] Preferred solution 1 further includes: the B section of the first fuel passage formed by the gap between the middle hole of the injector body and the tappet, the C section of the first fuel passage formed by the gap between the middle hole of the injector body and the connecting sleeve, the A section of the second fuel passage located on the side of the V-shaped body, the B section of the second fuel passage located in the hole wall of the injector body and penetrating from top to bottom, the C section of the second fuel passage on the side of the needle valve body, and the pressure accumulation chamber located between the check valve and the D section of the second fuel passage; the A section of the first fuel passage, the B section of the first fuel passage, the C section of the first fuel passage, the inlet throttle orifice, the D section of the first fuel passage, and the dispersion orifice are connected; the pressure accumulation chamber, the A section of the second fuel passage, the B section of the second fuel passage, the C section of the second fuel passage, the D section of the second fuel passage, and the oil storage gap are connected.

[0017] In preferred embodiment 2, the dispersed holes are 6 to 10 holes evenly distributed at the bottom of the needle valve, and the diameter of each hole is between 0.15-0.4 mm.

[0018] Preferred solution three, the control valve assembly includes: a valve seat, a valve core, an armature, an armature return spring, an armature return spring seat, and an armature support spring; the sealing surface of the valve seat is conical and the valve core is spherical; the center of the valve seat has an oil outlet throttling hole, the lower end of which is connected to a control chamber, and also includes a valve seat tightening cap, which presses the valve seat into the interior of a cylindrical chamber; the bottom surface of the valve seat, the top surface of the push rod, and the inner cylindrical surface of the push rod sleeve surround the control chamber.

[0019] Preferred solution four, the electromagnet assembly includes: a cylindrical cavity, an oil return port, a coil socket, a coil, a static iron, and an electromagnet tightening cap, the electromagnet tightening cap presses the electromagnet in the cylindrical cavity, and the oil return port releases the fuel flowing out of the injector.

[0020] Preferred solution five, the push rod needle valve assembly specifically includes: a push rod, the upper part of the push rod is sleeved with the inner surface of a push rod sleeve to maintain a dynamic sealing state, and the lower part of the push rod is a needle valve; a groove is processed on the push rod, and a spring card is fixed, and there is a push rod spring between the bottom surface of the push rod sleeve and the spring card, so that the push rod acts on a downward spring force; the end of the needle valve body is a needle valve seat, and the needle valve seat includes a section of inner conical surface, and the end of the needle valve includes two outer conical surfaces, which are respectively The first outer conical surface and the second outer conical surface, the taper of the first outer conical surface is smaller than that of the second outer conical surface, and the two intersect to form a sealing ring belt. When the needle valve is seated, the sealing ring belt is sealed with the inner conical surface of the valve seat, and at this time, the first fuel or the second fuel cannot be sprayed out from the injector; the lower end of the needle valve seat is a pressure chamber, and there is a spray hole in the pressure chamber; the gap formed between the first outer conical surface and the inner conical surface is an oil storage gap; the inner port of the distribution hole is connected to the end of the D section of the first fuel channel, and its outer port is connected to the oil storage gap.

[0021] Preferred solution six is ​​that there is also an annular groove at the lower end of the needle valve, which is located at the upper part of the sealing ring belt and constitutes a part of the oil storage gap and communicates with the outer port of the distribution hole.

[0022] The advantages of this patent over the prior art are:

[0023] (I) The method of controlling the amount of fuel injected by a conventional common rail injector is to use the injection pressure P and the injection duration T, which is named the PT method. T is controlled by a control valve. To achieve dual fuel injection, two independent control valves and injection channels are required.

[0024] (2) This patent proposes a new dual-fuel injector. Its working principle uses the pressure difference ΔP between the two fuels and the total accumulator volume V that can include an accumulator chamber to control the injection quantity of the first fuel for ignition, which is called the PV method here. There is no need to add a second control valve for independent control. Only a common control valve is needed to achieve the control of the injection quantities of the two fuels. The hydraulic circuit layout is compact, the mechanism is simple, the injector has a small volume, high reliability, low cost, is compatible with the existing installation method of common rail injectors, and is easy for engineering applications. Description of the Drawings

[0025] Figure 1 It is a schematic cross-sectional structure diagram of the dual-fuel injector in Embodiment 1.

[0026] Figure 2 It is a schematic cross-sectional structure diagram of the dual-fuel injector in Embodiment 3.

[0027] Figure 3 For Figure 1 Or Figure 2 The partial enlarged structure diagram of the part circled by I in — the bottom of the needle valve.

[0028] Figure 4 For Figure 1 Or Figure 2 The partial enlarged structure diagram of the part circled by II in — the control valve assembly.

[0029] Figure 5 For Figure 1 Or Figure 2 The partial enlarged structure diagram of the part circled by III in — the parts near the connecting sleeve.

[0030] Figure 6 It is the partial enlarged structure diagram of the bottom of the needle valve in Embodiment 2.

[0031] Figure 7 It is the injection rate curve diagram of the first fuel and the second fuel in the above embodiments. The a curve represents the driving pulse waveform, the b curve represents the diesel injection rate, and the c curve represents the methanol injection rate; the abscissa represents the injection time, and the ordinate represents the injection rate. Detailed Embodiments

[0032] Embodiment 1

[0033] A dual-fuel injector, which successively includes from bottom to top: an injector body 46, a V-shaped body 3, an electromagnet assembly 1, a needle valve body 5 connected to the lower end of the injector body, a tightening cap 41 connecting the injector body and the needle valve body, and a needle valve 4 located inside the needle valve body; the electromagnet assembly includes: a cylindrical cavity, an oil return port 101, a coil socket 102, a coil 103, a static iron 104, and an electromagnet tightening cap 105; the cylindrical cavity is a columnar cavity formed by enclosing a cylindrical cavity wall 42; the electromagnet tightening cap presses the electromagnet in the cylindrical cavity, and the oil return port releases the first fuel flowing out of the injector; the injector body is internally provided with: a tappet needle valve assembly, specifically including: a tappet 15, a connecting sleeve 16 is fixed to the lower part thereof, the upper part of the connecting sleeve is fixedly connected to the tappet, the inner surface of the lower part thereof is sleeved with the upper end of the needle valve and maintains a dynamic sealing fit state, the upper part of the tappet is sleeved with the inner surface of a tappet sleeve 17 and maintains a dynamic sealing state. A groove is machined on the tappet, and a spring clip 31 is fixed thereon. Between the bottom surface of the tappet sleeve and the spring clip, there is a tappet spring 32, so that the tappet acts with a downward spring force;

[0034] It further includes: a control valve assembly 2 located inside the V-shaped body, a first fuel interface 43 and a second fuel interface 44 located on the V-shaped body, a first fuel connector 33 connected to the first fuel interface, a one-way valve 14 connected to the second fuel interface, a first fuel inlet 7 located on the first fuel connector 43, and a second fuel inlet 8 located on the one-way valve;

[0035] A section A of the first fuel channel located on the center line of the first fuel connector and the first fuel interface; a section B of the first fuel channel formed by the gap between the middle hole of the injector body and the tappet, a section C of the first fuel channel formed by the gap between the middle hole of the injector body and the connecting sleeve, a section D of the first fuel channel located on the center line of the needle valve, and the upper port of section D is blocked and not connected to the upper end surface of the needle valve. An oil inlet throttle hole 10 connecting section C of the first fuel channel and section D of the first fuel channel. A dispersion hole 11 located at the bottom of the needle valve and at the lower end of the first fuel D channel is 6 to 10 uniformly distributed holes, and its diameter is between 0.15 - 0.4 mm. The section A of the first fuel channel, the section B of the first fuel channel, the section C of the first fuel channel, the oil inlet throttle hole, the section D of the first fuel channel, and the dispersion hole are successively connected; as Figure 1 、 Figure 4 shown, section A of the first fuel channel 22 also goes upward through the outer circular left side channel of the tappet sleeve 17 and communicates with the oil inlet throttle hole 19 of the control chamber.

[0036] The A section 26 of the second fuel passage located on the center line of the second fuel joint, the B section 25 of the second fuel passage located inside the wall of the injector body hole and penetrating from top to bottom, a C section 24 of the second fuel passage on the side of the needle valve body, a D section 23 of the second fuel passage formed by the gap between the needle valve and the needle valve body, and a pressure accumulation chamber 13 located inside the one-way valve body 1401; the second fuel inlet 8, the one-way valve 14, the pressure accumulation chamber, the A section of the second fuel passage, the B section of the second fuel passage, the C section of the second fuel passage, and the D section of the second fuel passage are connected in sequence;

[0037] As Figure 3 shown, the end of the needle valve body is a needle valve seat 28, the needle valve seat includes an inner conical surface 29, and the end of the needle valve includes two intersecting outer conical surfaces, which are the first outer conical surface 47 and the second outer conical surface 48 from top to bottom; the taper of the first outer conical surface is smaller than that of the second outer conical surface, and the two intersect to form a sealing ring belt 45; when the needle valve drops, the sealing ring belt 45 contacts and cooperates with the inner conical surface 29 for sealing; the lowermost end of the needle valve seat is a pressure chamber 49, and a spray hole 6 is connected to the periphery of the pressure chamber;

[0038] The gap formed between the first outer conical surface and the inner conical surface is the oil storage gap 12;

[0039] The inner side of the dispersion hole is connected to the end of the D section of the first fuel passage, and its outer side is connected to the oil storage gap;

[0040] One end of the pressure accumulation chamber is connected to the A section of the second fuel passage, and the other end is connected to the one-way valve.

[0041] The one-way valve includes: a one-way valve body 1401, a one-way valve seat 1402, a valve core 1403 and a return spring 1404, and the valve core 1403 is a sphere.

[0042] The pressure accumulation chamber is a cavity section located at the outlet of the one-way valve, and its volume can be set according to the needs of controlling the first fuel and the injection amount. As a special case, when the sum of the volumes of the second fuel passage between the pressure accumulation chamber and the outer end of the dispersion hole 11 has met the requirements, the volume of the pressure accumulation chamber is selected to be zero, that is, there is no need to specifically set up a pressure accumulation chamber.

[0043] Figure 3As shown in the figure, the control valve assembly includes: a valve seat 201, a valve core 202, an armature 203, an armature return spring 204, an armature return spring seat 205, and an armature support spring 206; the sealing surface of the valve seat 201 is conical, and the valve core 202 is spherical; at the center of the valve seat 201, there is an oil outlet throttle hole 207, the lower end of which communicates with the control chamber 18, and further includes a valve seat retaining cap 208 for pressing the valve seat inside the cylindrical chamber, and the bottom surface of the valve seat 201 constitutes the top surface of the control chamber 18; there is a control chamber inlet throttle hole 19 on the side wall of the control chamber, which communicates the control chamber with the left outer circular channel of the tappet sleeve 17, and this left channel communicates with the A section of the first fuel channel.

[0044] The control process is as follows:

[0045] Step 1: The driving current enters the coil through the coil socket, the static iron is magnetized to generate magnetic force, attracting the armature to rise against the spring force of the armature return spring 204, and the valve core also rises and disengages from the valve seat. The first fuel in the control chamber 18 overflows through the oil outlet throttle hole, the pressure in the control chamber 18 decreases, the downward hydraulic pressure of the tappet decreases, and the tappet lifts.

[0046] Step 2: A connecting sleeve is fixed to the lower end of the tappet. The connecting sleeve and the outer cylindrical surface of the upper end of the needle valve form a dynamic seal pair. The rise of the tappet will create a vacuum between the lower end surface of the tappet and the upper end surface of the needle valve, which will "attract" the needle valve to rise and follow the movement.

[0047] Step 3: After the driving current stops, the static iron magnetic force disappears. Under the spring force of the armature return spring, the armature drives the valve core to descend to the valve seat, the oil outlet throttle hole is cut off, and the first fuel enters the control chamber 18 through the control chamber inlet throttle hole 19, resulting in an increase in its pressure and an increase in the downward hydraulic pressure. When the downward hydraulic pressure + tappet spring force > upward hydraulic pressure, the tappet drives the needle valve to move downward, and finally the needle valve contacts and seals with the needle valve seat; in this embodiment, the oil supply pressure difference ⊿P between the first fuel and the second fuel is between 2 and 5 MPa. The first fuel enters the injector from the first fuel inlet and successively passes through the first fuel passage section A, the first fuel passage section B, the first fuel passage section C, the inlet throttle hole, the first fuel section D, and the dispersion hole, and enters the oil storage gap; during this process, the second fuel originally existing in the oil storage gap 12 is compressed and retreats, and finally reaches the accumulator chamber along the second fuel passage section D, the second fuel passage section C, the second fuel passage section B, and the second fuel passage section A. Due to the existence of the check valve, the second fuel will not flow back out of the second fuel inlet 8. Therefore, the pressure of the second fuel in the accumulator chamber will rise until it is equal to the pressure of the first fuel. At this time, the first fuel stops flowing out of the first fuel dispersion hole, and the accumulation process of the first fuel in the body ends; the accumulated amount of the first fuel in the oil storage gap is proportional to the pressure difference ⊿P between the first fuel and the second fuel, and the total accumulator volume V including the oil storage gap, the second fuel passage section D, the second fuel passage section C, the second fuel passage section B, the second fuel passage section A, and the accumulator chamber, and is also inversely proportional to the elastic modulus of the second fuel;

[0048] Step 4: After the accumulation process of the first fuel ends, the needle valve is controlled to lift. The first fuel in the oil storage gap, under the extrusion of its own storage pressure and the pressure of the second fuel, passes through the sealing ring belt and enters the pressure chamber, and finally sprays out from the spray hole; when the first fuel is almost completely sprayed, the needle valve is controlled to seat, and the first fuel pre-injection ends;

[0049] Step 5: A short pause occurs, and the needle valve is controlled to lift again. At this time, the first fuel in the oil storage gap is close to 0. The second fuel successively passes through the second fuel inlet 8, the check valve, the accumulator chamber, the second fuel passage section A, the second fuel passage section B, the second fuel passage section C, the second fuel passage section D, the oil storage gap, the pressure chamber, and finally sprays out from the spray hole, starting the main injection process mainly with the second fuel;

[0050] Step 6: Then the needle valve is controlled to seat, and the second fuel injection process ends; the injection amount of the second fuel depends on the injection duration T and the oil supply pressure P of the second fuel.

[0051] Such as Figure 7As shown, curve a represents the driving pulse, which consists of a short pulse, an interval, and a long pulse. Curve b represents the fuel injection law of the first fuel, diesel, in this embodiment, and curve c represents the fuel injection law of the second fuel, methanol, in this embodiment. During the short pulse, the diesel accumulated in the fuel storage gap 12 is pushed out of the injection hole 6 to form a pilot injection, that is, step 4 mentioned above. During the long pulse, methanol is directly sprayed out of the injection hole 6 to form a main injection, that is, steps 5 and 6 mentioned above. During the actual operation of the engine, the electronic fuel injection system controls the pressure difference ⊿P between the two fuels and the width of the short pilot pulse according to the demand for the amount of pilot diesel in different working conditions. According to the working conditions and power demand of the engine, the long pulse width T and the injection pressure P of methanol are determined.

[0052] The above is a two-injection process. It can also be divided into 3 times, 4 times, or even more times according to the requirements of the combustion process organization.

[0053] Embodiment 2

[0054] The bottom of the needle valve in this embodiment is different from that in Embodiment 1, and the rest, including the control process, is exactly the same as that in Embodiment 1. The differences are as Figure 6 shown. The technical details are as follows:

[0055] There is an annular groove 27 adjacent to the upper part of the needle valve sealing ring belt 45, which is communicated with the outside of the dispersion hole 11. Its advantage is that during the accumulation process of the first fuel, the first fuel is dispersed more evenly, and the interface between the two fuels is neater, so that the minimum injection amount of the first fuel can be smaller.

[0056] Embodiment 3

[0057] Comparison Figure 2 , the difference between this embodiment and Figure 1 the embodiment 1 shown lies in the positions of the first fuel interface, the first fuel return port, and the second fuel interface. The main functional difference between Embodiment 3 and the previous embodiments is the installation method of the fuel injector.

[0058] The first fuel interface 43 is located on the outer peripheral surface of the injector body, and the first fuel channel section A 22 is formed by drilling through the injector body wall; a vertical channel and a horizontal channel are opened on the injector body to divert the overflowed first fuel back to the first fuel return port 101; the second fuel interface 44 is located at a position with the same height as and opposite to the first fuel interface. The one-way valve and the pressure accumulation chamber of the second fuel can be external, and the principle is the same as that of other previous embodiments, so it will not be described here.

[0059] As Figure 7As shown by curve b, during the main injection, i.e., methanol injection, since the pressure of diesel is higher than that of methanol, a part of diesel will also be ejected mixed with methanol through the dispersion holes. However, due to the flow-limiting effect of the fuel inlet throttle hole, the amount of diesel ejected with methanol will be relatively small. Compared with the injection process, the time of injection stop occupies a relatively long time. Therefore, the existence of the fuel inlet throttle hole will not affect the accumulation process of diesel. The accumulation amount of diesel is mainly related to the pressure difference ⊿P between the two fuels and the total accumulator volume V including the accumulator chamber.

[0060] From the above principle, it can be seen that if the pressure difference ⊿P between the first fuel and the second fuel is changed, the storage amount of the first fuel can be changed, and thus the maximum allowable injection amount of the first fuel in the pilot pre-injection can be determined.

[0061] The above examples mainly focus on two liquid fuels, the first fuel and the second fuel. For example, the first fuel is diesel or biodiesel, and the second fuel is methanol, ethanol or liquid ammonia. If the first fuel is a liquid and the second fuel is a high-pressure gas, such as hydrogen or CNG, the working principle is the same. However, due to the large compressibility of the gas, to control the amount of pilot pre-injection, the total accumulator volume V must be reduced. For example, the check valve is transferred into the V-body or the injector body. At the same time, the pressure difference between the two fuels also needs to be controlled relatively small. This will not be elaborated here.

Claims

1. A dual fuel injector, comprising, from bottom to top: An injector body (46), an electromagnet assembly (1), a needle valve body (5) connected to the lower end of the injector body, and a needle valve (4) located in the needle valve body; the injector body comprises a central hole, and a tappet needle valve assembly is built in the central hole; the injector body is characterized in that it also comprises: The first fuel channel section A (22), the first fuel channel section D (9) located on the center line of the needle valve, and the oil inlet throttling hole (10) connected in series between the sections A and D; a one-way valve (14), a second fuel channel D section (23) formed by a gap between the needle valve and the needle valve body; An oil storage gap (12), the oil storage gap is located at the periphery of the needle valve (4) head and the upper part of the sealing ring (45), and the upstream of the oil storage gap is connected to the one-way valve through the second fuel channel D section; A plurality of distribution holes (11) are located at the lower part of the needle valve, wherein the inner ports thereof are communicated with the lower part of the first fuel channel D section, and the outer ports thereof are communicated with the lower part of the oil storage gap.

2. A dual fuel injector according to claim 1, characterized in that: Also includes: A first fuel channel section B (20) formed by a gap between a central hole of the injector body and a tappet, a first fuel channel section C (21) formed by a gap between the central hole of the injector body and a connecting sleeve, a second fuel channel section A (26) located on a second fuel joint and a center line of a second fuel interface, a second fuel channel section B (25) located in a hole wall of the injector body and passing through from top to bottom, a second fuel channel section C (24) on a side of a needle valve body, and a pressure storage chamber (13) located between a one-way valve and a second fuel channel section D; The first fuel channel section A, the first fuel channel section B, the first fuel channel section C, the oil inlet throttling hole, the first fuel channel section D, and the distribution hole are connected; The pressure accumulation chamber, the second fuel channel section A, the second fuel channel section B, the second fuel channel section C, the second fuel channel section D, and the oil storage gap are communicated with each other.

3. A dual fuel injector according to claim 1, characterized in that: The dispersed holes are 6 to 10 holes evenly distributed at the bottom of the needle valve, and the diameter of each hole is between 0.15-0.4 mm.

4. A dual fuel injector according to claim 1, characterized in that: The control valve assembly comprises: a valve seat (201), a valve core (202), an armature (203), an armature return spring (204), an armature return spring seat (205), and an armature support spring (206); the sealing surface of the valve seat is conical, and the valve core is spherical; the center of the valve seat has an oil outlet throttling hole (207), the lower end of which is connected to the control chamber, and also includes a valve seat tightening cap (208) for pressing the valve seat into the interior of a cylindrical cavity; the bottom surface of the valve seat, the top surface of the push rod, and the inner cylindrical surface of the push rod sleeve surround the control chamber.

5. A dual fuel injector according to claim 1, characterized in that: The electromagnet assembly comprises: a cylindrical cavity wall (42), an oil return port (101), a coil socket (102), a coil (103), a static iron (104), and an electromagnet tightening cap (105). The electromagnet tightening cap presses the electromagnet in the cylindrical cavity, and the oil return port releases the fuel flowing out of the injector.

6. A dual fuel injector according to claim 1, characterized in that: The tappet needle valve assembly specifically comprises: a tappet (15), the upper portion of which is sleeved with the inner surface of a tappet sleeve (17) to maintain a dynamic sealing state, and a needle valve is disposed below the tappet (15); A groove is processed on the push rod, and a spring card (31) is fixed thereon. A push rod spring (32) is provided between the bottom surface of the push rod sleeve and the spring card, so that the push rod acts with a downward spring force. The end of the needle valve body is a needle valve seat (28), and the needle valve seat includes an inner conical surface (29). The end of the needle valve includes two outer conical surfaces, which are a first outer conical surface (47) and a second outer conical surface (48) from top to bottom. The taper of the first outer conical surface is smaller than that of the second outer conical surface. The two intersect to form a sealing ring 45. When the needle valve is seated, the sealing ring is sealed with the inner conical surface of the valve seat. The gap formed between the first outer conical surface and the inner conical surface is an oil storage gap (12); The inner port of the distribution hole is connected to the end of the D section of the first fuel channel, and the outer port thereof is connected to the oil storage gap.

7. A dual fuel injector according to any one of claims 1 to 6, characterized in that: There is also an annular groove at the lower end of the needle valve, which is located at the upper part of the sealing ring belt and constitutes a part of the oil storage gap and communicates with the outer end of the distribution hole.

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