Injector valve seat and preparation method therefor, injector, engine, and vehicle

Abstract

The present application provides an injector valve seat, which is used for a methanol direct injector, the injector valve seat comprising a valve seat body and a protective coating provided on the outer surface of the valve seat body. The present application further provides a preparation method of the injector valve seat, and an injector using the injector valve seat, an engine, and a vehicle. The injector valve seat, injector, engine, and vehicle provided by the present application are applicable to methanol fuel. The corrosion resistance and wear resistance of the injector valve seat are enhanced, and the reliability of the injector, engine, and vehicle is also improved.

Description

Injector valve seat and preparation method thereof, injector, engine and vehicle

[0001] This application claims priority to Chinese patent application No. 202311114940.9 filed on August 31, 2023, entitled “Injector valve seat, method for preparing same, injector and engine”, Chinese patent application No. 202311442569.9 filed on November 1, 2023, entitled “A metal part”, and Chinese patent application No. 202311568124.5 filed on November 21, 2023, entitled “Injector valve seat, method for preparing injector valve seat, injector and vehicle”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of vehicle technology, and in particular to an injector valve seat and a preparation method thereof, as well as an injector, an engine, and a vehicle using the injector valve seat. Background Art

[0003] Methanol, as a fuel, offers abundant raw materials, is clean and environmentally friendly, and has excellent power performance, making it an ideal clean and renewable energy source. Methanol vehicles are an effective way to address carbon peak and achieve carbon neutrality.

[0004] The fuel supply system for methanol vehicles previously utilized intake manifold multi-point injection technology, but this solution proved less than ideal. Low methanol injection pressure and poor atomization resulted in poor fuel economy and emissions. With increasing demands for fuel economy and increasingly stringent emissions regulations, technological innovation in methanol supply systems is becoming increasingly urgent. Direct injection is a proven, mature technology in gasoline engines, offering significant improvements in fuel economy and emissions. Therefore, methanol engines using direct injection represent a promising technology.

[0005] Summary of the Invention

[0006] The purpose of this application is to provide an injector valve seat suitable for methanol fuel, a method for making the same, and an injector, engine, and vehicle using the same. The injector valve seat and its method for making the same balance the requirements for mild steel, which require good corrosion resistance to high-temperature methanol and formic acid, and high hardness, thereby alleviating the technical contradiction in the carbon content requirement for the injector valve seat. The seat also improves the corrosion and wear resistance of the injector valve seat, effectively resolving the technical issue of abnormal injection in methanol direct injection injectors in the related art and enhancing the reliability of the injector, engine, and vehicle.

[0007] To achieve the above objectives, a first aspect of the present application provides an injector valve seat, comprising a valve seat body and a protective coating disposed on an outer surface of the valve seat body, wherein the protective coating comprises Ti and CrN.

[0008] Optionally, the protective coating comprises at least a Ti base layer and a CrN layer which are stacked.

[0009] Optionally, the protective coating includes a base layer, an intermediate layer and a surface layer, which are stacked in sequence on at least part of the outer surface of the valve seat body; the material of the base layer includes Ti, the material of the intermediate layer includes CrN, and the material of the surface layer includes Ti.

[0010] Optionally, the thickness of the primer layer is 0.3 μm-3.0 μm, the thickness of the intermediate layer is 0.6 μm-6.0 μm, and the thickness of the surface layer is 0.3 μm-3.0 μm.

[0011] Optionally, the valve seat body is provided with an injection hole and an inner cavity for accommodating a valve ball. The injection hole is provided on the bottom wall of the inner cavity and passes through the bottom wall. The bottom wall is used to match the shape of the spherical surface of the valve ball. The injection hole is used to cooperate with the valve ball to open or close the injection hole.

[0012] The first aspect of the present application also provides an injector valve seat, comprising a valve seat body, the valve seat body being made of low-carbon stainless steel and having a contact surface, the protective coating comprising a nitriding layer formed on the contact surface and a silicon coating formed on the surface of the nitriding layer.

[0013] Optionally, the carbon content of the low-carbon stainless steel is less than 0.1%.

[0014] Optionally, the thickness of the nitriding layer is 2 μm-20 μm; the thickness of the silicon coating is 0.1 μm-0.5 μm.

[0015] Optionally, a chromium nitride coating is formed on the surface of the silicon coating away from the nitriding layer; the chromium nitride content in the chromium nitride coating is greater than 80%, and the thickness of the chromium nitride coating is 0.6 μm-1 μm.

[0016] Optionally, a sealing functional layer is formed on the surface of the chromium nitride coating away from the silicon coating, the hardness of the sealing functional layer is lower than the hardness of the chromium nitride coating, and the corrosion resistance of the sealing functional layer is higher than the corrosion resistance of the chromium nitride coating.

[0017] Optionally, the sealing functional layer is a chromium coating; the thickness of the chromium coating is 0.3 μm to 0.7 μm.

[0018] Optionally, a gradual transition layer is provided between the chromium coating and the chromium nitride coating; in the gradual transition layer, along the direction from the chromium nitride coating to the chromium coating, the content of chromium nitride gradually decreases, and the content of chromium gradually increases.

[0019] Optionally, the valve seat body is provided with a spray hole, the cross-sectional area of ​​the spray hole decreases from the spray hole inlet to the spray hole outlet; and the spray hole inlet of the spray hole is rounded.

[0020] Optionally, the injection hole is conical, and the cone angle of the injection hole is 2 to 15°; the radius of the fillet is 0.003 to 0.15 mm.

[0021] Optionally, the hardness of the surface layer of the injector valve seat is 700-1500 HV, wherein the thickness of the surface layer is 0.02-0.5 mm.

[0022] A second aspect of the present application provides a method for preparing an injector valve seat, comprising the following steps:

[0023] The valve seat body of the injector valve seat is made of a valve seat base material, and the materials of the valve seat base material include C, Si, Mn, P, S, Cr, Mo, and V;

[0024] forming a primer layer on at least a portion of the outer surface of the valve seat body;

[0025] forming an intermediate layer on the outer surface of the base layer;

[0026] A surface layer is formed on the outer surface of the intermediate layer.

[0027] Optionally, the material of the valve seat substrate has chemical composition mass fractions corresponding to: C < 0.35% - 0.9%, Si < 1.0%, Mn < 1.0%, P < 0.04%, S < 0.04%, Cr < 15% - 18%, Mo < 1.8%, V < 0.3%.

[0028] Optionally, forming a primer layer on at least a portion of the outer surface of the valve seat body comprises:

[0029] Ti is used as the target material and argon is used as the protective gas to form a base layer on at least part of the outer surface of the valve seat body through an arc plating process; the gas pressure during the arc plating process is 0.3Pa-0.9Pa, the bias voltage is 250V, the target current is 65A-75A, the deposition temperature is 240℃-270℃, and the arc plating time is 5h-8h.

[0030] Optionally, forming the intermediate layer on the outer surface of the primer layer comprises:

[0031] Pure chromium is used as the target material and nitrogen is used as the reaction gas to form an intermediate layer on the outer surface of the base layer through an arc plating process; the nitrogen flow rate range during the arc plating process is 250sccm-500sccm, the target current is 80A-100A, and the arc plating time is 20-25h.

[0032] Optionally, forming the surface layer on the outer surface of the intermediate layer comprises:

[0033] Ti is used as the target material and argon is used as the protective gas to form a surface layer on the outer surface of the intermediate layer through an arc plating process; the gas pressure during the arc plating process is 0.3Pa-0.9Pa, the bias voltage is 250V, the target current is 65A-75A, the deposition temperature is 240℃-270℃, and the arc plating time is 5h-8h.

[0034] Optionally, the method further comprises the following steps:

[0035] Processing and forming a spray hole on the valve seat body;

[0036] A rounded corner is formed at the injection hole entrance of the injection hole.

[0037] Optionally, the step of machining the injection hole on the valve seat body includes:

[0038] The injection hole is formed on the valve seat body by laser drilling equipment, wherein the processing conditions of the injection hole include: laser power of 0.8-1.5kW, repetition frequency of 7-10kHz, defocusing amount of -350-450μm, scanning speed of 0.01-0.02mm / s, and number of scans of 15-25 times.

[0039] Optionally, the step of forming a rounded corner at the injection hole entrance of the injection hole comprises:

[0040] A polishing liquid is used to impact the injection hole entrance of the injection hole to form a rounded corner at the injection hole entrance of the injection hole.

[0041] Optionally, the polishing fluid includes silicone rubber, lubricating fluid, silicon carbide particles and an anti-sticking agent;

[0042] The mass proportion of the silicone rubber in the polishing liquid is 30%-40%;

[0043] And / or, the mass proportion of the lubricating liquid in the polishing liquid is 20%-30%;

[0044] And / or, the mass proportion of the silicon carbide particles in the polishing liquid is 35%-45%.

[0045] Optionally, the step of forming a rounded corner at the injection hole entrance of the injection hole further comprises:

[0046] After machining the fillet at the injection hole entrance of the injection hole, an injector valve seat intermediate piece is obtained;

[0047] Installing a shielding tool on the surface to be welded of the injector valve seat intermediate piece;

[0048] The injector valve seat middle piece on which the shielding tooling is installed is subjected to nitriding treatment to form a protective coating, thereby obtaining the injector valve seat.

[0049] Optionally, the processing conditions of the nitriding treatment include: the nitriding medium is ammonia, the nitriding temperature is less than or equal to 460°C, the nitriding time is greater than or equal to 150h, the nitriding thickness is 0.02-0.5mm, and the deformation of the injector valve seat before and after nitriding treatment is less than or equal to 0.01mm.

[0050] A third aspect of the present application further provides an injector, comprising the injector valve seat as described above.

[0051] Optionally, the injector further includes a valve body, a valve needle, and a valve ball. The injector valve seat is fixed at one end of the valve body. The valve body is provided with a valve cavity. The injector valve seat is connected to the valve cavity. The valve needle is movably arranged in the valve cavity. The valve ball is fixed at the end of the valve needle. The valve ball is movably arranged in the injector valve seat.

[0052] A fourth aspect of the present application also provides an engine, comprising the injector as described above.

[0053] A fifth aspect of the present application also provides a vehicle, comprising the engine as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] FIG1 is a cross-sectional schematic diagram of an injector valve seat and an injector using the injector valve seat provided by a first preferred embodiment of the first aspect of the present application.

[0055] FIG2 is a schematic cross-sectional view of the protective coating of the injector valve seat shown in FIG1 ;

[0056] FIG3 is a cross-sectional view of the valve seat body of the injector valve seat shown in FIG1 ;

[0057] FIG4 is a cross-sectional view of the valve seat body shown in FIG3 when it is installed in the coating tooling;

[0058] FIG5 is a flow chart of a method for preparing an injector valve seat provided by a first preferred embodiment of the second aspect of the present application;

[0059] FIG6 is a schematic diagram of an injector valve seat manufactured by the method shown in FIG5 after a durability test.

[0060] FIG7 is a partial cross-sectional schematic diagram of an injector valve seat provided by a second preferred embodiment of the first aspect of the present application.

[0061] FIG8 is a cross-sectional schematic diagram of an injector using the injector valve seat shown in FIG7 ;

[0062] FIG9 is a schematic cross-sectional view of the valve core in FIG8 ;

[0063] FIG10 is a schematic cross-sectional view of the injector valve seat in FIG8 .

[0064] FIG11 is a cross-sectional schematic diagram of an injector valve seat provided by the third preferred embodiment of the first aspect of the present application.

[0065] FIG. 12 is a schematic diagram showing cavitation occurring in an injection hole in an injector valve seat in the prior art.

[0066] FIG13 is a schematic structural diagram of the fillet in the injector valve seat shown in FIG11 .

[0067] FIG14 is a schematic cross-sectional view of the injection hole in the injector valve seat shown in FIG11 .

[0068] FIG15 is a schematic diagram showing that no cavitation occurs in the injection hole of the injector valve seat shown in FIG11 .

[0069] FIG16 is a flow chart of a method for preparing an injector valve seat provided in a second preferred embodiment of the second aspect of the present application.

[0070] FIG17 is a schematic diagram of a scenario in which a shielding tool is installed in the injector valve seat shown in FIG11 . DETAILED DESCRIPTION

[0071] To make the above-mentioned purposes, features, and advantages of the present application more clearly understood, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making any creative work are within the scope of protection of this application.

[0072] At present, there are still some difficulties in applying the direct injection mode in methanol engines, such as:

[0073] 1. Methanol itself has poor lubricity, and its corrosiveness to metals increases significantly with increasing temperature. At the same time, the valve seat of the injector is in the high-temperature and high-pressure environment of the engine combustion chamber and is often subjected to high-frequency impact forces. Therefore, problems such as corrosion and wear of the valve seat are prone to occur during operation, which can lead to failure of the valve seat seal of the injector and affect the reliability of the injector operation.

[0074] 2. When the methanol direct injection injector operates in a high-temperature and high-pressure environment, due to the physical and chemical properties of methanol itself, methanol fuel is prone to generate bubbles during the injector injection process. During the bubble bursting process, micro-jets and impact force are generated, which will destroy the surface characteristics of the injector injection hole, that is, cause cavitation problems, and lead to abnormal injector injection status.

[0075] 3. In terms of physical properties, injector valve seats require high hardness and wear resistance. Therefore, traditional valve seat materials typically use stainless steel with a carbon content of 0.2% or higher to achieve sufficient hardness. However, in terms of chemical properties, methanol direct injection injectors require strong corrosion resistance because they must resist both high-temperature methanol corrosion and formic acid and other derivatives generated by methanol in this environment. Stainless steels with good resistance to high-temperature methanol and formic acid corrosion are generally low-carbon alloy stainless steels with a carbon content of 0.1% or lower. Furthermore, during validation testing of methanol direct injection injectors, multiple cases of injector valve seat wear occurred. Failure mode analysis determined the cause to be carbon precipitation on the valve seat surface in the high-temperature methanol environment, causing accelerated wear, leading to valve seat sealing failure and methanol leakage from the injector. Therefore, to improve corrosion resistance and mitigate damage caused by carbon precipitation, methanol direct injection injectors should be manufactured from low-carbon stainless steel. However, corrosion-resistant stainless steels with a carbon content of less than 0.1% have a low hardness and are difficult to meet the wear resistance requirements for valve seats. In other words, the performance requirements of both physical and chemical properties create a technical contradiction with the demand for the carbon content of the valve seat material.

[0076] In order to resolve the above-mentioned technical contradictions, some existing methanol direct injection injectors are made of low-carbon stainless steel, and coating technology is used to improve the surface strength to take into account both corrosion resistance and wear resistance. In the currently disclosed valve seat coating technology, such as the valve seat DLC coating, the coating material is usually a metastable amorphous material generated by combining sp3 and sp2 bonds. Due to the low hardness of the low-carbon acid-resistant stainless steel valve seat material, the valve seat surface will produce slight deformation when the injector is working. This deformation will cause the internal stress of the DLC coating to increase, and eventually lead to the fracture and failure of the sp3 and sp2 bonds. Therefore, the valve seat currently made of conventional materials and DLC technology is not suitable for methanol direct injection injector valve seats.

[0077] In order to solve the above-mentioned technical problems, it is necessary to provide an injector valve seat suitable for methanol fuel with better performance, a preparation method thereof, and an injector, engine, and vehicle using the injector valve seat. Referring to Figures 1-3, a first preferred embodiment of the first aspect of the present application provides an injector valve seat 10 suitable for a methanol direct injection injector. The injector valve seat 10 includes a valve seat body 11 and a protective coating 12 disposed on the outer surface of the valve seat body 11. The protective coating 12 includes a primer layer 121, an intermediate layer 122, and a surface layer 123. The primer layer 121, the intermediate layer 122, and the surface layer 123 are sequentially stacked on at least a portion of the outer surface of the valve seat body 11. The material of the primer layer 121 includes Ti, the material of the intermediate layer 122 includes CrN, and the material of the surface layer 123 includes Ti.

[0078] The valve seat body 11 is provided with an injection hole 112 and an inner cavity 111 for accommodating a valve ball 20 (as shown in FIG1 , described in detail below). The injection hole 112 is provided on and extends through a bottom wall 1111 of the inner cavity 111 to inject the fuel. The bottom wall 1111 is configured to match the spherical shape of the valve ball 20, and the injection hole 112 cooperates with the valve ball 20 to open or close the injection hole 112.

[0079] Preferably, the protective coating 12 is only provided on the outer surface of the valve seat body 11, and the cavity wall of the inner cavity 111 (not marked in the figure) is not provided with the protective coating 12, so as to prevent the presence of the protective coating 12 on the cavity wall of the inner cavity 111 from changing the gap between the valve ball 20 and the cavity wall, thereby affecting the movement of the valve ball 20 in the inner cavity 111 and the cooperation between the valve ball 20 and the injection hole 112.

[0080] More specifically, the base layer 121 has a strong bonding force with the base material of the valve seat body 11 and the base layer 121 itself has strong corrosion resistance; the intermediate layer 122 has the characteristics of low stress, high adhesion, high toughness, and high corrosion resistance, and has corrosion resistance and chemical resistance to aqueous solutions, and has a certain lubricity; the surface layer 123 is arranged on the outer surface of the intermediate layer 122, which can further enhance the corrosion resistance and wear resistance of the protective coating 12.

[0081] Referring to FIG. 1 to FIG. 6 , a first preferred embodiment of the second aspect of the present application further provides a method for preparing an injector valve seat, which can be used to prepare the injector valve seat 10 provided in the first preferred embodiment of the first aspect of the present application. The method comprises the following steps:

[0082] (1) Preparing the valve seat body 11: The valve seat body 11 of the injector valve seat 10 is made of a preset valve seat base material, wherein the material of the valve seat base material includes C, Si, Mn, P, S, Cr, Mo, and V, and the corresponding chemical composition mass fractions are: C < 0.35% - 0.9%, Si < 1.0%, Mn < 1.0%, P < 0.04%, S < 0.04%, Cr < 15% - 18%, Mo < 1.8%, and V < 0.3%;

[0083] (2) Pre-treating the valve seat body 11: Immerse the valve seat body 11 in a special cleaning solution and perform ultrasonic cleaning twice, each treatment lasting 15 minutes to 30 minutes, and then dry it. After the valve seat body 11 is cleaned and dried, the pre-prepared coating tool 100 is installed in the inner cavity 111 of the valve seat body 11, and then placed in a coating furnace together;

[0084] (3) Evacuating the coating furnace: closing the furnace chamber of the coating furnace, turning on the rotary vane vacuum pump, and waiting for the air pressure in the furnace to drop below 10 Pa, starting the molecular pump to further increase the air pressure to the ultimate vacuum degree, and maintaining the ultimate vacuum environment for a period of time to remove the air in the furnace to the maximum extent;

[0085] (4) forming a base layer 121: using Ti as a target material and argon as a shielding gas, forming the base layer 121 with a thickness of 0.3 μm to 3.0 μm, preferably 1.2 μm or 1.5 μm, on at least a portion of the outer surface of the valve seat body 11 by an arc plating process, wherein the arc plating process is performed at a gas pressure of 0.3 Pa to 0.9 Pa, a bias voltage of 250 V, a target current of 65 A to 75 A, a deposition temperature of 240° C. to 270° C., and an arc plating time of 5 h to 8 h;

[0086] (5) Forming the intermediate layer 122: using pure chromium as a target material and nitrogen as a reaction gas, the intermediate layer 122 with a thickness of 0.6 μm to 6.0 μm is formed on the outer surface of the base layer 121 by the arc plating process, wherein the flow rate of the nitrogen during the arc plating process is in the range of 250 sccm to 500 sccm, the target current is 80 A to 100 A, and the arc plating time is 20 to 25 hours;

[0087] (6) Forming a surface layer 123: Using Ti as a target material and argon as a shielding gas, the surface layer 123 having a thickness of 0.3 μm to 3.0 μm is formed on the outer surface of the intermediate layer 122 by the arc plating process, wherein the gas pressure during the arc plating process is 0.3 Pa to 0.9 Pa, the bias voltage is 250 V, the target current is 65 A to 75 A, the deposition temperature is 240° C. to 270° C., and the arc plating time is 5 h to 8 h;

[0088] (7) After preparation, turn off all power supplies, ion sources and gas sources.

[0089] More specifically, the coating tool 100 comprises a top cover 101 and a mounting post 102. The top cover 101 is fixed to the mounting post 102. The shape and size of the mounting post 102 match the inner cavity 111 of the valve seat body 11. The mounting post 102 is used to install the coating tool 100 into the valve seat body 11. The top cover 101 is used to block the protective coating 12 from being applied to the inner cavity 111 during the preparation of the injector valve seat 10. The coating tool 100 cooperates with the inner cavity 111 of the valve seat body 11 and functions to prevent the protective coating 12 from being applied to the walls of the inner cavity 111.

[0090] More specifically, the effect of evacuating the coating furnace is to increase the density of the coating and reduce the porosity of the coating.

[0091] More specifically, when forming the base layer 121 and the surface layer 123 , protective gas argon is introduced with a gas pressure ranging from 0.3 Pa to 0.9 Pa, which prevents the base layer 121 and the surface layer 123 from being oxidized and nitrided.

[0092] Preferably, when the thickness of the base layer 121 is 0.3μm-1.5μm, the thickness of the intermediate layer 122 is 0.6μm-2.0μm, and the thickness of the surface layer 123 is 0.3μm-1.5μm, the injector valve seat 10 is subjected to an injector monomer durability test of 600 million times and an engine bench durability test of 800 hours. The injector valve seat 10 shows no signs of corrosion, and the flow rate and air tightness of the injector meet the design requirements, proving that the injector valve seat 10 meets the use requirements.

[0093] Referring again to Figures 1 and 3 , a first preferred embodiment of the third aspect of the present application further provides an injector 1 comprising a valve body 30, a valve needle 40, a valve ball 20, a return spring 60, an electromagnetic actuator 50, and the injector valve seat 10 described above. The injector valve seat 10 is fixed to one end of the valve body 30. The valve body 30 defines a valve chamber 31 filled with fuel. The injector valve seat 10 communicates with the valve chamber 31. The valve needle 40 is movably disposed within the valve chamber 31. The valve ball 20 is fixed to the distal end of the valve needle 40 and movably disposed within the injector valve seat 10. The return spring 60 is fixed within the valve chamber 31 and connected to the top end of the valve needle 40. The return spring 60 is in a compressed state. The electromagnetic actuator 50 is fixed to the valve body 30 and connected to the valve needle 40. The electromagnetic actuator 50 can drive the valve needle 40 to move up and down along the valve chamber 31.

[0094] The initial position of the valve ball 20: the valve ball 20 abuts against the bottom wall 1111 of the inner cavity 111 of the injector valve seat 10 and cooperates with the injection hole 112 to prevent the fuel from passing through the injection hole 112. When the injector 1 needs to inject the fuel, the injector 1 drives the valve needle 40 to move upward along the valve cavity 31 through the electromagnetic drive 50, and the valve ball 20 follows the valve needle 40 to move upward and away from the bottom wall 1111, and the fuel is sprayed into the combustion chamber (not shown) through the injection hole 112; when the injector does not need to inject the fuel, the electromagnetic drive 50 stops working, the return spring 60 stretches and drives the valve needle 40 to move downward along the valve cavity 31, and the valve ball 20 follows the valve needle 40 to move downward until it abuts against the bottom wall 1111 and cooperates with the injection hole 112 to prevent the fuel from passing through the injection hole 112.

[0095] In addition, the first preferred embodiment of the fourth aspect of the present application also provides an engine (not shown) comprising the injector 1 .

[0096] The beneficial effects of the above-mentioned injector valve seat and preparation method thereof, injector and engine provided by the above-mentioned embodiments of the first to fourth aspects of the present application are: being suitable for methanol fuel, not only improving the corrosion resistance and wear resistance of the injector valve seat, but also improving the reliability of the injector and engine.

[0097] Referring to FIG7 , a second preferred embodiment of the first aspect of the present application provides an injector valve seat 10A capable of adapting to high-temperature methanol corrosion environments. The injector valve seat 10A comprises a valve seat body 1A and a protective coating disposed on the outer surface of the valve seat body 1A. The valve seat body 1A is made of low-carbon stainless steel, preferably with a carbon content of 0.1% or less, as this type of stainless steel exhibits excellent corrosion resistance to high-temperature methanol and formic acid. The valve seat body 1A has a contact surface S, and the protective coating comprises a nitrided layer 2A formed on the contact surface S and a silicon coating 3A formed on the surface of the nitrided layer 2A. The contact surface S is the contact and sealing surface of the valve seat body 1A for contacting the valve core. The nitrided layer 2A improves the cavitation resistance of the contact surface S of the valve seat body 1A, particularly the cavitation resistance of the micropore inner surface, and increases the hardness of the low-carbon stainless steel metal substrate. This ensures that the low-carbon stainless steel exhibits excellent hardness while maintaining high-temperature methanol and formic acid corrosion resistance. A silicon coating 3A is formed on the surface of the nitrided layer 2A. Leveraging the acid corrosion resistance of the silicon coating 3A, the risk of trace amounts of carbon precipitating as carbon compounds from the contact surface S of the low-carbon stainless steel is further reduced, thereby further enhancing the corrosion resistance of the contact surface S of the valve seat body 1A. The silicon coating 3A can be formed using a siliconizing process, serving as a high-temperature methanol corrosion-resistant layer to prevent corrosion of the valve seat body 1A by high-temperature methanol. Specifically, the silicon coating 3A can be formed using an ion sputtering process.

[0098] The contact surface S refers to the surface that contacts methanol or a high-temperature methanol environment and bears impact loads or friction loads. The surface may be the sealing contact surface between the valve seat and the valve core and valve ball.

[0099] In a specific embodiment, the thickness of the nitriding layer 2A is between 2 μm and 20 μm, and can be specifically 2 μm, 4 μm, 6 μm, 7 μm, 9 μm, 12 μm, 14 μm, 15 μm, 17 μm, 19 μm and 20 μm, etc. Within this thickness range, the anti-cavitation performance of the inner surface of the micropores can be fully improved, while the surface hardness of the valve seat body 1A can be improved, and at the same time the nitriding cost can be limited to a reasonable range.

[0100] In a specific embodiment, the thickness of the silicon coating 3A is between 0.1 μm and 0.5 μm, and specifically can be 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, etc. When the thickness of the silicon coating 3A is within this range, the precipitation of carbon in the form of carbon compounds can be substantially reduced, thereby achieving sufficient corrosion resistance while also taking into account reasonable costs.

[0101] In one specific embodiment, a chromium nitride coating 4A is formed on the surface of the silicon coating 3A facing away from the nitrided layer 2A. The chromium nitride coating 4A can simultaneously improve the wear resistance and corrosion resistance of the contact surface S of the valve seat body 1A, which is subjected to impact loads. The chromium nitride coating 4A can be formed using a chromium nitriding process and has a higher hardness and better impact resistance than the silicon coating 3A.

[0102] In a specific embodiment, the chromium nitride coating 4A contains greater than 80% chromium nitride, and the thickness of the chromium nitride coating 4A is between 0.6 μm and 1 μm, specifically 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, and 1 μm. When the thickness of the chromium nitride coating 4A is within this range, the wear resistance and corrosion resistance of the contact surface S can be maintained while maintaining reasonable cost.

[0103] In a specific embodiment, a sealing functional layer 5A is formed on the surface of the chromium nitride coating 4A facing away from the silicon coating 3A. The hardness of the sealing functional layer 5A is lower than that of the chromium nitride coating 4A, which can accelerate the running-in speed between the contact surface S and the matching surface, such as increasing the running-in speed between the valve seat and the valve core and valve ball, and quickly forming a sealing surface in the initial stage of injector operation. In addition, the corrosion resistance of the sealing functional layer 5A is higher than that of the chromium nitride coating 4A, thereby further improving the corrosion resistance.

[0104] In one specific embodiment, the sealing functional layer 5A is a chromium coating. The chromium coating has lower hardness than the chromium nitride coating 4A and higher corrosion resistance than the chromium nitride coating 4A, making it an ideal material for the sealing functional layer 5A. The thickness of the chromium coating can be between 0.3 μm and 0.7 μm, specifically 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, and 0.7 μm. This thickness range balances hardness, corrosion resistance, and reasonable cost.

[0105] In a specific embodiment, a gradual transition layer is provided between the chromium coating and the chromium nitride coating 4A. In the gradual transition layer, the chromium nitride content gradually decreases and the chromium content gradually increases along the direction from the chromium nitride coating 4A to the chromium coating, so as to gradually evolve toward the composition of the chromium coating and avoid a poor combination due to a large difference in composition between the two.

[0106] Please refer to Figures 8 to 10 together. The second preferred embodiment of the third aspect of the present application also provides an injector, which includes the above-mentioned injector valve seat 10A, as well as the valve core 20A and the valve body 30A. A conical surface on the injector valve seat 10A contacts the ball head of the valve core 20A to form a contact sealing surface. The ball head of the valve core 20A and the conical sealing surface of the injector valve seat 10A form a kinematic pair that is subjected to impact loads. In a specific embodiment, the injector valve seat 10A is a valve seat for a methanol direct injection injector, and the contact surface S is the contact sealing surface between the valve seat body 1A and the valve core 20A. The injector valve seat 10A is arranged at the oil outlet end of the valve body 30A, and the valve core 20A is arranged in the space of the valve body 30A, and is sealed with the contact sealing surface of the valve seat body 1A through the valve ball at the end. By performing surface treatment on the contact surface S of the valve seat body 1A, the hardness of the contact sealing surface between the valve seat body 1A and the valve core 20A can be increased, while the use of low-carbon stainless steel can prevent carbon precipitation of the valve seat body 1A.

[0107] The third preferred embodiment of the first aspect of the present application also provides an injector valve seat 10B, comprising a valve seat body and a protective coating disposed on the outer surface of the valve seat body. The valve seat body may be the valve seat body 11 described in the first preferred embodiment of the first aspect of the present application or the valve seat body 1A described in the second preferred embodiment of the first aspect of the present application, and no further description is required here. Referring to FIG. 11 , the valve seat body of the injector valve seat 10B is provided with an injection hole 11B, the cross-sectional area of ​​the injection hole 11B gradually decreasing from the injection hole inlet 111B to the injection hole outlet 112B; the injection hole 11B has rounded corners at the injection hole inlet 111B and / or the injection hole outlet 112B.

[0108] In this embodiment, it should be noted that methanol can be produced from a wide range of raw materials, such as coal, natural gas, and biomass, making it possible for industrial application. In addition, methanol is a high-oxygen fuel with a fast combustion rate, a wide ignition range, and no soot is produced after combustion. Therefore, it is a carbon-neutral fuel with broad development prospects. In the field of automotive and marine internal combustion engines, methanol fuel is becoming increasingly important. Currently, methanol vehicles use an intake manifold multi-point injection technology solution. This solution has low methanol injection pressure and poor atomization, resulting in poor fuel economy and emissions. As users' requirements for economy become higher and higher and emission regulations become more and more stringent, technological innovation in the methanol supply system is becoming more urgent. Direct injection technology has been verified in the field of gasoline engines and has obvious effects on economy and emission improvement. Therefore, direct injection methanol engines are also a technical route with great development prospects.

[0109] However, methanol direct-injection injectors experienced abnormal fuel injection. Actual bench tests verified that gasoline direct-injection injectors did not exhibit surface cavitation of the injection holes. To address the technical issues surrounding abnormal fuel injection in methanol direct-injection injectors, it was further discovered that methanol direct-injection injectors, installed in the cylinder, operate at pressures of 350-1000 bar and temperatures of 300-500°C. During injection, fuel enters the smaller injection hole from the larger injector cavity, causing a further surge in pressure at the injection hole entrance. When methanol fuel is used, this can easily generate bubbles at the injection hole entrance, accompanied by their bursting. These bubbles can impact the injection hole entrance, damaging its surface features and, in severe cases, causing the injector to fail.

[0110] FIG12 shows a case where the injection hole inlet of an existing methanol direct injection injector is damaged due to impact force.

[0111] In this embodiment, the injector valve seat 10B is disposed at the distal end of the injector. A spray hole 11B is defined in the injector valve seat 10B, through which the injector can spray a high-pressure fuel spray. It should be noted that while this embodiment addresses the technical drawback that bubbles are easily generated during methanol fuel injection, which can damage the surface features of the injector spray hole 11B and, in severe cases, lead to the ineffective operation of the injector, the injector valve seat 10B of this embodiment can be applied to methanol direct injection injectors, other injectors using methanol as fuel, or injectors using other fuels, and this embodiment is not intended to limit this.

[0112] The cross-sectional area of ​​the injection hole 11B decreases from the injection hole inlet 111B to the injection hole outlet 112B. In other words, the diameter of the injection hole 11B gradually decreases from the injection hole inlet 111B to the injection hole outlet 112B. This gradually reduces the space for fuel to enter, dispersing the pressure at the injection hole inlet 111B and preventing the sudden influx of fuel into a small space, which could cause a sudden increase in pressure at the injection hole inlet 111B.

[0113] Optionally, the injection hole 11B is conical, and the cone angle of the injection hole 11B is 2 to 15 degrees.

[0114] In this embodiment, the smoother the inner wall of the injection hole 11B, the more stable the gas pressure of the fuel in the injection hole 11B. When the injection hole 11B is conical, the fuel flows smoothly from the injection hole inlet 111B to the injection hole outlet 112B in the injection hole 11B, which can achieve uniform dispersion of pressure, thereby reducing local cracking or damage. If the cone angle of the injection hole 11B is too small, the greater the pressure change at the injection hole inlet 111B, the greater the impact that the injection hole inlet 111B needs to withstand, and the more likely it is to be damaged. However, if the cone angle of the injection hole 11B is too large, since the overall structure and volume of the injector valve seat 10B are fixed, it may affect other structures of the injector valve seat 10B, such as the number of injection holes 11B and the wall thickness of the injection holes 11B. A reduction in the number of injection holes 11B may affect the performance of the injector, and excessively thin wall thickness at the injection hole 11B may also lead to insufficient strength at the injection hole 11 and damage. Therefore, the cone angle of the injection hole 11B is determined to be 2 to 15°, for example, 2°, 5°, 8°, 10°, 12°, 15°, etc.

[0115] The injection hole 11B is rounded at its inlet 111B. During the injection process, stress is easily concentrated at corners, which can cause cracks. Rounded corners help reduce stress concentration, thereby preventing damage caused by stress concentration. They also further disperse pressure at the injection hole inlet 111B, mitigating sudden pressure changes when fuel enters the injection hole 11B from the injector chamber. This improves the durability of the injector valve seat 10B and extends its service life.

[0116] Optionally, the radius of the fillet is 0.003-0.15 mm.

[0117] In this embodiment, if the radius of the fillet is larger, the curvature of the fillet is also larger, and the wall thickness at the injection hole entrance 111B is smaller. Too small a wall thickness may cause insufficient strength of the injection hole 11B. If the radius of the fillet is too small, the pressure dispersion effect is not obvious. Therefore, the radius of the fillet is determined to be 0.003~0.15mm, for example, 0.003mm, 0.01mm, 0.05mm, 0.1mm, 0.15mm, etc.

[0118] In one practicable manner, the rounded corners are as shown in FIG13 .

[0119] Optionally, the hardness of the surface layer of the injector valve seat 10B is 700-1500 HV, wherein the thickness of the surface layer is 0.02-0.5 mm.

[0120] In this embodiment, the surface layer of the injector valve seat 10B refers to a region with a thickness of 0.02 to 0.5 mm near the surface of the injector valve seat 10. This may be a region of the injector valve seat 10 where a protective coating is provided, or a region of the injector valve seat 10 where no protective coating is provided. The specific thickness of the surface layer can be determined based on actual needs and is not limited in this embodiment.

[0121] The higher the hardness of the surface layer of the injector valve seat 10B, the less likely it is to break when impacted. However, if the hardness is too high, the surface layer of the injector valve seat 10B will become more brittle and more likely to break when impacted. Therefore, the hardness of the surface layer of the injector valve seat 10B is determined to be 700-1500 HV, for example, 700 HV, 900 HV, 1200 HV, 1500 HV, etc. The hardness of the surface layer of the injector valve seat 10 can be controlled by selecting the material of the injector valve seat 10, surface treatment, processing a high-hardness surface layer, etc. The specific hardness can be determined according to actual conditions and is not limited in this embodiment.

[0122] In one embodiment, referring to FIG14 , the injector valve seat 10B further includes a large injection hole 12B. The injection hole 11B connects the injector chamber and the large injection hole 12B, and the large injection hole 12B connects the injection hole 11B and the combustion chamber. The large injection hole 12B can be designed according to actual needs and is not limited in this embodiment.

[0123] In this embodiment, the injector valve seat is provided with an injection hole, the cross-sectional area of ​​which decreases from the injection hole inlet to the injection hole outlet; and the injection hole inlet is rounded. Before the injector injects fuel, the injection hole on the injector valve seat is disconnected from the injector chamber within the injector. During fuel injection, the injection hole and the injector chamber are connected, and the fuel enters the smaller injection hole from the larger injection chamber, causing a sudden increase in pressure at the injection hole inlet. In the case of methanol fuel, methanol fuel is prone to generating bubbles at the injection hole inlet, which are accompanied by bubble collapse. The bubble collapse causes impact force at the injection hole inlet, damaging the surface features at the injection hole inlet. By making the cross-sectional area of ​​the injection hole gradually decrease from the injection hole inlet to the injection hole outlet, the present application can achieve a pressure dispersion effect, gradually increasing the pressure as the fuel passes through the injection hole, avoiding sudden changes in pressure at the injection hole inlet. Furthermore, by making the injection hole inlet rounded, the present application can further disperse the pressure at the injection hole inlet, mitigating the sudden change in pressure when the fuel enters the injection hole from the injector chamber. This allows fuel to enter and be ejected more smoothly through the injection hole. This reduces the generation and collapse of bubbles at the injection hole entrance, even when methanol fuel is used, thereby reducing damage at the injection hole entrance and minimizing fuel injection anomalies caused by such damage. This resolves the technical issue of fuel injection anomalies in methanol direct injection injectors in the related art, effectively improving the durability of the injector and extending its service life. Furthermore, after 600 million cycles of endurance testing of the injector unit and 800 hours of bench endurance testing on the engine, the injection hole, as shown in Figure 15, shows no cavitation failure. The performance of the injector valve seat provided in the application meets the design requirements and meets the requirements of use.

[0124] Furthermore, a second preferred embodiment of the second aspect of the present application further provides a method for preparing an injector valve seat, which can be used to prepare the injector valve seat 10B provided in the third preferred embodiment of the first aspect of the present application. Referring to FIG. 16 , the method comprises the following steps:

[0125] Step S10, providing a valve seat body; wherein the valve seat body can adopt the valve seat body 11 in the first preferred embodiment of the first aspect of the present application or the valve seat body 1A in the first preferred embodiment of the first aspect of the present application, which need not be repeated here.

[0126] Step S20: forming a spray hole on the valve seat body.

[0127] In this embodiment, it should be noted that the valve seat body can be a block of material having a certain injector valve seat shape and structure and requiring injection hole processing. For example, a valve seat body without an injection hole or with an injection hole that does not meet the requirements can be processed by cutting, injection molding, 3D printing, etc. according to the required shape and structure of the injector valve seat, wherein the requirement for the injection hole is that the cross-sectional area decreases from the injection hole inlet to the injection hole outlet. If the existing production line can produce a valve seat body with an injection hole that does not meet the requirements, or if a valve seat body with an injection hole that does not meet the requirements can be purchased, the injection hole that does not meet the requirements can be reprocessed so that the cross-sectional area of ​​the injection hole decreases from the injection hole inlet to the injection hole outlet. The processing method of the valve seat body can be determined according to actual needs, and this embodiment does not limit this.

[0128] As an example, the steps S10 to S20 include: providing a pre-prepared valve seat body, and using a punching device to process the injection hole on the valve seat body, the cross-sectional area of ​​which decreases from the injection hole inlet to the injection hole outlet.

[0129] In one practicable embodiment, before forming the injection hole on the valve seat body, the process may further include: cleaning the valve seat body. For example, the valve seat body may be immersed in a cleaning solution and ultrasonically cleaned one or more times, each ultrasonic cleaning lasting 15 to 30 minutes. The injection hole may then be processed after drying.

[0130] Optionally, the step of machining and forming the injection hole on the valve seat body includes:

[0131] The injection hole is processed on the valve seat body by laser drilling equipment, wherein the processing conditions of the injection hole include: laser power of 0.8-1.5kW, repetition frequency of 7-10kHz, defocusing amount of -350-450μm, scanning speed of 0.01-0.02mm / s, and number of scans of 15-25 times.

[0132] As an example, a laser drilling device can be used to machine a jet hole with a cross-sectional area decreasing from the jet hole inlet to the jet hole outlet on the valve seat body by adjusting the direction of the workpiece or the direction of the laser, etc. Wherein, the processing conditions of the laser drilling device for machining the jet hole include: a laser power of 0.8 to 1.5 kW, such as 0.8 kW, 1.0 kW, 1.2 kW, 1.5 kW, etc., a repetition frequency of 7 to 10 kHz, such as 7 kHz, 8 kHz, 9 kHz, 10 kHz, etc., a defocus of -350 to 450 μm, such as -350 μm, -200 μm, 50 μm, 250 μm, 450 μm, etc., a scanning speed of 0.01 to 0.02 mm / s, such as 0.01 mm / s, 0.015 mm / s, 0.02 mm / s, etc., and a scanning number of 15 to 25 times, such as 15 times, 20 times, 25 times, etc.

[0133] In step S30, a fillet is formed at the injection hole entrance of the injection hole, thereby obtaining the injector valve seat 10B.

[0134] As an example, step S30 includes: after the injection hole is machined, the injection hole entrance of the injection hole may be further machined to form a rounded corner, thereby obtaining the injector valve seat 10B. The rounded corner machining method includes grinding, impacting, etc.

[0135] Optionally, the step of forming a rounded corner at the injection hole entrance of the injection hole comprises:

[0136] A polishing liquid is used to impact the injection hole entrance of the injection hole to form a rounded corner at the injection hole entrance of the injection hole.

[0137] As an example, a polishing liquid can be used to impact the injection hole entrance of the injection hole. The impact force of the polishing liquid on the injection hole entrance can be used to form a rounded corner with a certain arc at the injection hole entrance, thereby obtaining the injector valve seat 10B. The polishing liquid can be configured or purchased according to actual needs and is not limited in this embodiment.

[0138] Optionally, the polishing fluid includes silicone rubber, lubricating fluid, silicon carbide particles and an anti-sticking agent.

[0139] Optionally, the mass proportion of the silicone rubber in the polishing liquid is 30%-40%;

[0140] And / or, the mass proportion of the lubricating liquid in the polishing liquid is 20%-30%;

[0141] And / or, the mass proportion of the silicon carbide particles in the polishing liquid is 35%-45%.

[0142] In this embodiment, the silicone rubber has a certain hardness and size distribution, and the silicon carbide particles have a greater hardness and strong cutting force. The combination of the two can improve the smoothness of the fillet while achieving rounded corner processing, and the efficiency of polishing the fillet is high. At the same time, it is equipped with a lubricant and an anti-sticking agent to reduce surface friction and avoid scratches and damage to the surface of the injector valve seat. The mass proportion of the silicone rubber in the polishing liquid is 30%-40%, for example, 30%, 35%, 40%, etc. The mass proportion of the lubricant in the polishing liquid is 20%-30%, for example, 20%, 25%, 30%, etc. The mass proportion of the silicon carbide particles in the polishing liquid is 35%-45%, for example, 35%, 40%, 45%, etc.

[0143] Optionally, the step of forming a rounded corner at the injection hole entrance of the injection hole comprises:

[0144] Step S31, after processing the fillet at the injection hole entrance of the injection hole, an injector valve seat intermediate piece is obtained;

[0145] Step S32, installing a shielding tool on the surface to be welded of the injector valve seat intermediate component;

[0146] Step S33 , performing nitriding treatment on the injector valve seat intermediate piece on which the shielding tooling is installed to form a protective coating, thereby obtaining the injector valve seat.

[0147] In this embodiment, it should be noted that a protective layer can be formed on the entire or partial surface of the valve seat body by surface nitriding treatment, thereby improving the hardness of the surface layer of the injector valve seat 10B. However, after processing, the injector valve seat 10B needs to be welded to the injector body. During the welding process, nitrogen will be precipitated in the area that has been nitrided due to heat, and a pore structure will be formed in the area after the nitrogen precipitation. When the surface with the pore structure is welded to the injector body, the welding tightness is low, which may lead to insufficient durability and a short service life of the injector in subsequent use. Therefore, in this embodiment, before nitriding treatment, a shielding tool is first installed on the surface to be welded of the injector valve seat middle piece (that is, the valve seat body that has been processed with a fillet structure at the injection hole entrance but has not yet been surface nitrided) to prevent the surface to be welded from being affected by the nitriding treatment. When only the surface layer is nitrided, the influence of nitriding treatment on the surface to be welded in other areas can be avoided by controlling process parameters such as nitriding time.

[0148] As an example, steps S31-S33 include: after machining the injection hole, further machining the injection hole entrance of the injection hole into a rounded corner to obtain the injector valve seat intermediate component. Then, a shielding tool is installed on the surface to be welded of the injector valve seat intermediate component. The injector valve seat intermediate component with the shielding tool installed is placed in a nitriding medium. Under certain conditions, the remaining areas of the injector valve seat, excluding the surface to be welded, are nitrided. After the nitriding treatment is completed, the shielding tool is removed to obtain the injector valve seat 10B.

[0149] Optionally, the processing conditions of the nitriding treatment include: the nitriding medium is ammonia, the nitriding temperature is less than or equal to 460° C., the nitriding time is greater than or equal to 150 h, and the nitriding thickness is 0.02-0.5 mm.

[0150] In this embodiment, ammonia can be used as a nitriding medium, and the nitriding temperature is controlled below 460°C. The nitriding treatment includes three processes: thermal decomposition of ammonia to produce active atoms, adsorption of active atoms on the surface of the injector valve seat, and diffusion of active atoms on the surface into the interior of the injector valve seat. The nitriding time is greater than or equal to 150 hours, and the nitriding thickness is 0.02-0.5mm. The nitriding thickness at different positions will have certain differences, and all are within the range of 0.02-0.5mm. After nitriding treatment, the hardness of the injector valve seat can reach the range of 700-1500HV, and the deformation of the injector valve seat before and after nitriding treatment is controlled to be less than or equal to 0.01mm.

[0151] In one practicable manner, referring to FIG17 , the outer surface of the upper end of the injector valve seat intermediate member is the surface to be welded, so a shielding tool 20B can be installed on the surface to be welded, and the shielding tool 20B can be interference-fitted with the upper end of the injector valve seat intermediate member to ensure the installation stability of the shielding tool. For example, the outer diameter of the upper end of the injector valve seat intermediate member is (0.01mm / 0.02mm), the inner diameter of the shielding tool is (-0.02mm / -0.01mm), thereby achieving interference fit, and the shielding tooling can use TP2 (deoxidized copper) material to facilitate sealing and disassembly.

[0152] The injector valve seat fabrication method provided in this application addresses the technical issue of abnormal fuel injection in methanol direct injection injectors in the related art. Compared to the prior art, the beneficial effects of the injector valve seat fabrication method provided in this embodiment of the application are similar to those of the injector valve seat 10B in the aforementioned embodiment and are not further elaborated here.

[0153] The third aspect of the present application provides an injector, which may be a methanol direct injection injector, comprising the injector valve seat provided by any one of the first to third preferred embodiments of the first aspect of the present application as described above.

[0154] A fourth aspect of the present application provides an engine comprising the injector as described above.

[0155] A fifth aspect of the present application provides a vehicle comprising the engine as described above.

[0156] Compared with the prior art, the injector, engine and vehicle provided in the embodiments of the present application can solve the technical problem of abnormal fuel injection of methanol direct injection injectors in the related art. Its specific beneficial effects are the same as the beneficial effects of the injector valve seat described in the above embodiments, and will not be repeated here.

[0157] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. An injector valve seat, characterized in that: The injector valve seat comprises a valve seat body and a protective coating arranged on the outer surface of the valve seat body, wherein the material in the protective coating comprises Ti and CrN.

2. The injector valve seat according to claim 1, characterized in that The protective coating at least includes a Ti primer layer and a CrN layer which are stacked.

3. The injector valve seat according to claim 1, characterized in that The protective coating includes a base layer, an intermediate layer and a surface layer, wherein the base layer, the intermediate layer and the surface layer are sequentially stacked on at least a portion of the outer surface of the valve seat body; the material of the base layer includes Ti, the material of the intermediate layer includes CrN, and the material of the surface layer includes Ti.

4. The injector valve seat according to claim 2, characterized in that The thickness of the base layer is 0.3 μm-3.0 μm, the thickness of the middle layer is 0.6 μm-6.0 μm, and the thickness of the surface layer is 0.3 μm-3.0 μm.

5. The injector valve seat according to any one of claims 1 to 4, characterized in that: The valve seat body is provided with an injection hole and an inner cavity for accommodating a valve ball. The injection hole is arranged on the bottom wall of the inner cavity and penetrates the bottom wall. The bottom wall is used to match the shape of the spherical surface of the valve ball. The injection hole is used to cooperate with the valve ball to open or close the injection hole.

6. An injector valve seat, comprising a valve seat body, characterized in that: The valve seat body is made of low-carbon stainless steel and has a contact surface. The protective coating comprises a nitriding layer formed on the contact surface and a silicon coating formed on the surface of the nitriding layer.

7. The injector valve seat according to claim 6, characterized in that The carbon content of the low carbon stainless steel is less than 0.1%.

8. The injector valve seat according to claim 6 or 7, characterized in that: The thickness of the nitriding layer is 2 μm-20 μm; the thickness of the silicon coating is 0.1 μm-0.5 μm.

9. The injector valve seat according to any one of claims 6 to 8, characterized in that: A chromium nitride coating is formed on the surface of the silicon coating away from the nitriding layer; the content of chromium nitride in the chromium nitride coating is greater than 80%, and the thickness of the chromium nitride coating is 0.6 μm-1 μm.

10. The injector valve seat according to claim 9, characterized in that A sealing function layer is formed on the surface of the chromium nitride coating away from the silicon coating. The hardness of the sealing function layer is lower than that of the chromium nitride coating, and the corrosion resistance of the sealing function layer is higher than that of the chromium nitride coating.

11. The injector valve seat according to claim 10, characterized in that The sealing function layer is a chromium coating; the thickness of the chromium coating is 0.3 μm-0.7 μm.

12. The injector valve seat according to claim 11, characterized in that A gradual transition layer is provided between the chromium coating and the chromium nitride coating; in the gradual transition layer, along the direction from the chromium nitride coating to the chromium coating, the content of chromium nitride gradually decreases, and the content of chromium gradually increases.

13. The injector valve seat according to any one of claims 5 to 12, characterized in that: The valve seat body is provided with a spray hole, the cross-sectional area of ​​the spray hole decreases from the spray hole inlet to the spray hole outlet; the spray hole inlet of the spray hole is rounded.

14. The injector valve seat according to claim 13, characterized in that The injection hole is conical, and the cone angle of the injection hole is 2-15°; the radius of the fillet is 0.003-0.15 mm.

15. The injector valve seat according to claim 13, characterized in that The hardness of the surface layer of the injector valve seat is 700-1500 HV, wherein the thickness of the surface layer is 0.02-0.5 mm.

16. A method for preparing an injector valve seat, comprising the following steps: The valve seat body of the injector valve seat is made of a valve seat substrate, and the material of the valve seat substrate includes C, Si, Mn, P, S, Cr, Mo, and V; forming a primer layer on at least a portion of the outer surface of the valve seat body; forming an intermediate layer on the outer surface of the base layer; A surface layer is formed on the outer surface of the intermediate layer.

17. The method according to claim 16, characterized in that The chemical composition mass fractions of the material of the valve seat substrate are: C<0.35%-0.9%, Si<1.0%, Mn<1.0%, P<0.04%, S<0.04%, Cr<15%-18%, Mo<1.8%, and V<0.3%.

18. The method according to claim 16 or 17, characterized in that Forming a primer layer on at least a portion of the outer surface of the valve seat body includes: Using Ti as the target material and argon as the protective gas, an arc plating process is used to form a base layer on at least part of the outer surface of the valve seat body; wherein the gas pressure during the arc plating process is 0.3Pa-0.9Pa, the bias voltage is 250V, the target current is 65A-75A, the deposition temperature is 240℃-270℃, and the arc plating time is 5h-8h.

19. The method according to any one of claims 16 to 18, characterized in that: Forming an intermediate layer on the outer surface of the primer layer includes: Pure chromium is used as a target material and nitrogen is used as a reaction gas to form an intermediate layer on the outer surface of the base layer through an arc plating process; wherein the flow rate of nitrogen during the arc plating process is in the range of 250sccm-500sccm, the target current is 80A-100A, and the arc plating time is 20-25h.

20. The method according to any one of claims 16 to 19, characterized in that: Forming the surface layer on the outer surface of the intermediate layer comprises: Using Ti as the target material and argon as the protective gas, a surface layer is formed on the outer surface of the intermediate layer through an arc plating process; wherein the gas pressure during the arc plating process is 0.3Pa-0.9Pa, the bias voltage is 250V, the target current is 65A-75A, the deposition temperature is 240℃-270℃, and the arc plating time is 5h-8h.

21. The method according to any one of claims 16 to 20, characterized in that: The method further comprises the following steps: Processing and forming a spray hole on the valve seat body; A rounded corner is formed at the injection hole entrance of the injection hole.

22. The method according to claim 21, characterized in that The step of machining and forming the injection hole on the valve seat body comprises: The injection hole is formed on the valve seat body by laser drilling equipment, wherein the processing conditions of the injection hole include: laser power of 0.8-1.5 kW, repetition frequency of 7-10 kHz, defocus of -350-450 μm, scanning speed of 0.01-0.02 mm / s, and scanning times of 15-25 times.

23. The method according to claim 21 or 22, characterized in that The step of forming a fillet at the injection hole entrance of the injection hole comprises: The polishing fluid is used to impact the injection hole entrance of the injection hole, and the injection hole entrance of the injection hole The mouth is rounded.

24. The method of claim 23, wherein: The polishing fluid comprises silicone rubber, lubricating fluid, silicon carbide particles and an anti-sticking agent; The mass proportion of the silicone rubber in the polishing liquid is 30%-40%; And / or, the mass proportion of the lubricating liquid in the polishing liquid is 20%-30%; And / or, the mass proportion of the silicon carbide particles in the polishing liquid is 35%-45%.

25. The method according to any one of claims 21 to 24, characterized in that The step of forming a fillet at the injection hole entrance of the injection hole further comprises: After machining the fillet at the injection hole entrance of the injection hole, an injector valve seat intermediate piece is obtained; Installing a shielding tool on the surface to be welded of the injector valve seat intermediate piece; The injector valve seat middle piece installed with the shielding tooling is nitrided to form a protective coating to obtain the injector valve seat.

26. The method of claim 25, wherein: The processing conditions of the nitriding treatment include: the nitriding medium is ammonia, the nitriding temperature is less than or equal to 460° C., the nitriding time is greater than or equal to 150 hours, the nitriding thickness is 0.02-0.5 mm, and the deformation of the injector valve seat before and after the nitriding treatment is less than or equal to 0.01 mm.

27. An injector, comprising the injector valve seat according to any one of claims 1 to 15.

28. The injector according to claim 27, characterized in that The injector also includes a valve body, a valve needle, and a valve ball. The injector valve seat is fixed at one end of the valve body. The valve body is provided with a valve cavity. The injector valve seat is connected to the valve cavity. The valve needle is movably arranged in the valve cavity. The valve ball is fixed at the end of the valve needle. The valve ball is movably arranged in the injector valve seat.

29. An engine comprising an injector as claimed in claim 27 or 28.

30. A vehicle comprising the engine of claim 29.

Images