High-flow T-shaped pressure accumulation type common rail oil injector

Abstract

The invention provides a large-flow T-shaped pressure accumulation type common rail oil injector which comprises an oil injector body and a control block, and a needle valve is installed at the lower end of the oil injector body; the needle valve comprises a valve body and a valve element. A transition block is arranged between the valve body and the oil sprayer body. A control valve rod is installed in a middle hole pressure storage cavity of the oil sprayer body, an electromagnetic valve, a compression nut and a control valve seat are sequentially installed in a control block from top to bottom, and a core rod is arranged at the lower end of an armature of the electromagnetic valve. A control cavity is formed between the control valve rod and the control valve seat; a transition cavity is arranged between the oil sprayer body and the control block, and the T-shaped pressure storage cavity on the control block and the oil inlet metering hole of the control valve seat are both communicated with the transition cavity. According to the fuel injector, the electromagnetic valve is integrated on the control block at the top end of the fuel injector body, electromagnetic interference is reduced, the stability of needle valve control is improved, the influence of previous injection on subsequent injection is reduced, the multiple injection capacity of the fuel injector and the fuel quantity control accuracy are improved, and therefore the working stability of the fuel injector is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of common rail injection systems, and in particular relates to a large-flow T-type pressure-accumulating common rail injector. Background Art

[0002] At present, diesel engines mainly use conventional high-pressure common rail fuel systems with common rail pipes, which makes it difficult to effectively match and apply high-power diesel engines with different cylinder sizes, different numbers of cylinders, and different power and speed requirements. Figure 8 The figure shows the structure of a conventional high-pressure common rail system. Although the conventional high-pressure common rail fuel system can achieve relative independence of the fuel supply process and the injection process through the common rail pipe, the required common rail pipe has high reliability requirements and large size. The low-frequency pressure wave of the pulsating fuel supply of the high-pressure oil pump coupled with the high-frequency pressure wave of the cyclic injection of the electronically controlled fuel injector causes the pressure in the common rail pipe to fluctuate violently, affecting the stability and consistency of the system's injection performance. At the same time, the common rail pipe is generally forged in an integrated manner. During the operation of the diesel engine, due to the high fuel pressure, internal defects in the forging process of the common rail pipe, and the fluctuation of the inner cavity pressure and other factors, the common rail pipe may be damaged, cracked, and other faults, resulting in reduced reliability of the diesel engine. Summary of the invention

[0003] In view of this, the invention aims to overcome the defects in the prior art and proposes a large-flow T-type accumulator common rail injector.

[0004] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0005] A large flow T-type pressure accumulator common rail injector comprises an injector body and a control block mounted on a compression sleeve, wherein the control block is located at the upper end of the injector body, and a needle valve is installed at the lower end of the injector body; the needle valve comprises a valve body and a valve core, a transition block is arranged between the valve body and the injector body, and the transition block is closely fitted with the injector body and the valve body respectively; a limit block is arranged at the upper end of the valve core, and a groove for accommodating the limit block is arranged on the upper end surface of the valve body, and an independent cavity is formed between the limit block and the transition block;

[0006] A middle hole pressure storage chamber is provided in the injector body, a control valve stem is installed in the middle hole pressure storage chamber, and the middle hole pressure storage chamber is provided with an upper accommodating section, a middle narrow mouth section and a lower accommodating section from top to bottom; an upper limit piece is provided at one end of the control valve stem in the upper accommodating chamber, and a lower limit piece is provided at one end of the control valve stem in the lower accommodating chamber; a coupling sleeve is provided in the lower accommodating chamber, the coupling sleeve is in clearance with the control valve stem, and a compression spring is provided between the coupling sleeve and the lower limit piece;

[0007] A small diameter section is provided in the middle of the control valve stem, the upper end of the small diameter section is higher than the top of the middle narrow section, and the lower end is higher than the bottom of the middle narrow section, so that a variable cross-section cavity is formed between the middle hole pressure storage cavity and the control valve stem. The change rule of the variable cross-section cavity structure from top to bottom is: the cross section of the variable cross-section cavity first changes from large to small, and then changes from small to large; the oil chamber in the valve body is connected with the middle hole pressure storage cavity through the through hole of the transition block;

[0008] The control block is equipped with a solenoid valve, a clamping nut and a control valve seat from top to bottom. The lower end of the armature of the solenoid valve is provided with a core rod, the upper end of which is clamped by an electromagnetic spring, and the lower end of which passes through a clamping nut, which is used to control the matching relationship between the sealing steel ball and the control valve seat, thereby realizing the on-off control of the oil return hole of the control valve seat; the clamping nut is screwed on the control block and clamps the control valve seat to the control block;

[0009] A mounting hole is provided at the lower end of the control valve seat, the upper end of the control valve stem is inserted into the mounting hole and slidably cooperates with the control valve seat, a return spring is provided between the limiter and the control valve seat, and a control cavity is formed between the control valve stem and the bottom of the mounting hole of the control valve seat; a transition cavity is provided between the injector body and the control block, and the T-shaped pressure storage cavity on the control block and the oil inlet hole of the control valve seat are both connected to the transition cavity.

[0010] Furthermore, the compression spring is sleeved on the control valve stem.

[0011] Furthermore, a return spring is sleeved on the control valve stem.

[0012] Furthermore, the needle valve is fixed to the fuel injector body through a nozzle cap.

[0013] Furthermore, the oil nozzle cap is screwed onto the fuel injector body.

[0014] Furthermore, a sealing member is provided between the control block and the compression sleeve.

[0015] Furthermore, a conical groove is provided on the upper end surface of the control valve seat, and a sealing conical surface is formed at the junction of the conical groove and the oil return hole.

[0016] Furthermore, the valve core lift of the needle valve is 0.45±0.01 mm.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] The present invention creates a solenoid valve of the fuel injector that is integrated into the control block at the top of the fuel injector body, reducing electromagnetic interference, and adopts a transverse built-in T-type pressure chamber structure above the fuel injector to form multiple pressure storage pipe sections that are flexibly arranged in sections, eliminating the integral common rail pipe, and reducing the installation and layout requirements of the common rail system itself, making the layout of the common rail system on the engine more flexible, and can be applied to distributed common rail systems. In addition to the transverse T-type pressure storage chamber above the fuel injector, a central hole pressure storage chamber is designed on the periphery of the control valve stem of the fuel injector, and an independent space is also provided between the valve core of the needle valve and the control valve stem, which not only provides a stable inlet boundary condition for the oil inlet throttling hole and improves the stability of the needle valve control, but also reduces the influence of the previous injection on the subsequent injection, improves the fuel injector's ability to inject multiple times and the accuracy of oil quantity control, thereby greatly improving the stability of the fuel injector's operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0020] Figure 1 A schematic diagram of the structure of a fuel injector is created for the present invention;

[0021] Figure 2 A schematic diagram of a control valve seat in the invention;

[0022] Figure 3 A schematic diagram of the upper structure of the fuel injector is created for the present invention;

[0023] Figure 4 A schematic diagram of the middle structure of the fuel injector created by the present invention;

[0024] Figure 5 for Figure 4 Schematic diagram without the control valve stem;

[0025] Figure 6 A schematic diagram of the lower structure of the fuel injector body is created by the present invention;

[0026] Figure 7 It is a schematic diagram of the independent space formed between the transition block and the limit block in the invention;

[0027] Figure 8 This is a schematic diagram of the structure of a conventional high-pressure common rail system. DETAILED DESCRIPTION

[0028] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0029] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0030] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0031] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0032] A large flow T-type pressure accumulator common rail injector, such as Figures 1 to 7 As shown, it includes an injector body 1 and a control block 2, which are fixed by a compression sleeve 3. The control block is located at the upper end of the injector body, and a seal 4 is provided between the control block and the compression sleeve. A needle valve 5 is installed at the lower end of the injector body, and the needle valve is fixed to the injector body through a nozzle cap 6. As an example, the nozzle cap is screwed on the injector body. The needle valve includes a valve body 7 and a valve core 8. A transition block 9 is provided between the valve body and the injector body, and the transition block is tightly fitted with the injector body and the valve body respectively; a limit block 10 is provided at the upper end of the valve core, and a groove 12 for accommodating the limit block is provided on the upper end surface of the valve body, and an independent cavity 13 is formed between the limit block and the transition block.

[0033] The fuel injector body is provided with a central hole pressure storage chamber 14, in which a control valve stem 15 is installed. The central hole pressure storage chamber is provided with an upper accommodating section 16, a middle narrow section 17 and a lower accommodating section 18 from top to bottom; the control valve stem is provided with an upper limit piece 19 at one end in the upper accommodating chamber, and a lower limit piece 20 at one end in the lower accommodating chamber; a coupling sleeve 21 is provided in the lower accommodating chamber, and the coupling sleeve is matched with the control valve stem clearance. For example, the clearance between the coupling sleeve and the control valve stem is 0.004-0.006mm. When the control valve stem of the fuel injector moves upward, due to the existence of the independent space, the upward movement of the control valve stem will produce a suction effect, which reduces the pressure on the upper end face of the needle valve, thereby lifting the valve core of the needle valve. It is precisely because of the existence of the clearance that the time for the external high-pressure oil to enter the "independent space" becomes longer, thereby being insensitive to the external high-pressure oil pressure change and improving stability. A compression spring 22 is provided between the coupling sleeve and the lower limit piece, and the compression spring is sleeved on the control valve stem.

[0034] A cylindrical transition block is designed between the lower end of the control valve stem and the needle valve to play a role in buffering and shock absorption. A limit block is provided at the upper end of the valve core to limit the position of the needle valve. The lower end of the control valve stem, the upper end of the needle valve (valve body), the transition block and the limit block together form an independent space, which is decoupled from the external high-pressure fuel. Therefore, the fuel in this chamber is almost unaffected by the pressure fluctuation caused by the injection, which is conducive to improving the stability of the control valve stem and the needle valve movement, thereby improving the stability and reliability of the injector. By selecting limit blocks of different thicknesses, the needle valve lift can be adjusted. The gap value between the limit block and the transition block is the needle valve lift. As an example, the valve core lift is 0.45±0.01mm.

[0035] In an optional embodiment, a small diameter section 23 is provided in the middle of the control valve stem, the upper end of the small diameter section is higher than the top 24 of the middle narrow section, and the lower end is higher than the bottom 25 of the middle narrow section, so that a variable cross-section cavity is formed between the middle hole pressure storage chamber and the control valve stem. The change rule of the variable cross-section cavity structure from top to bottom is: the cross section of the variable cross-section cavity first changes from large to small, and then changes from small to large. When the control valve stem moves up and the valve core opens, the control valve stem and the injector body are connected to the above-mentioned variable cross-section cavity structure, which produces a Venturi effect, making the injection speed faster. The oil chamber 46 in the valve body is connected to the middle hole pressure storage chamber through the through hole 26 of the transition block.

[0036] The control block is equipped with a solenoid valve 27, a clamping nut 28 and a control valve seat 29 from top to bottom. The lower end of the armature of the solenoid valve is provided with a core rod 30, the upper end of which is clamped by an electromagnetic spring 31, and the lower end of which passes through the clamping nut, which is used to control the matching relationship between the sealing steel ball 32 and the control valve seat, thereby realizing the on-off control of the oil return hole 33 of the control valve seat. Usually, the clamping nut is screwed on the control block and the control valve seat is clamped and fixed on the control block, so that the control valve seat and the control block are precisely fitted to ensure high-pressure sealing.

[0037] A mounting hole 34 is provided at the lower end of the control valve seat, and the upper end of the control valve stem is inserted into the mounting hole and slidably cooperates with the control valve seat. A return spring 35 is provided between the limiter and the control valve seat, and the return spring is sleeved on the control valve stem to form a control chamber 36 between the control valve stem and the bottom of the mounting hole of the control valve seat; a transition chamber 37 is provided between the injector body and the control block, and the T-shaped pressure storage chamber 38, the middle hole pressure storage chamber, and the oil inlet hole 39 of the control valve seat on the control block are all connected to the transition chamber. The injector created by the present invention adopts a T-shaped transverse built-in pressure storage chamber structure above, forming multiple pressure storage pipe sections that are flexibly arranged in sections, eliminating the integral common rail pipe, making the control of the injection amount and injection time more precise, reducing the installation and layout requirements of the common rail system itself, and further improving safety.

[0038] The upper end surface of the control valve seat is provided with a conical groove 40, and a sealing cone 41 is formed at the junction of the conical groove and the oil return hole. In an optional embodiment, the oil return hole includes a middle column section 42, an upper column section 43 is provided on the upper side of the middle column section, and a lower column section 44 is provided on the lower side, a transition cone section 45 is provided between the lower column section and the middle column section, and a concave platform 11 is provided on the lower side of the lower column section, the diameter of the lower column section is smaller than the diameter of the upper column section, and the diameter of the upper column section is smaller than the diameter of the middle column section, and the diameter of the concave platform is larger than the diameter of the middle column section. The structural design of the oil return hole is conducive to shifting the cavitation position downward, which can avoid the generation of cavitation at the sealing position of the sealing ball and the valve seat of the control valve assembly, and improve the reliability of the sealing between the sealing ball and the valve seat.

[0039] In the invention, the solenoid valve is integrated inside the control block, which can reduce electromagnetic interference. The variable cross-section structural design of the oil return hole improves the stability of the ball valve movement under 200MPa, and effectively inhibits the formation of cavitation in the oil return channel, blocks the cavitation formed by the oil return throttling hole and the ball valve and the valve seat, reduces the formation of cavitation on the sealing surface of the ball valve, and greatly improves the sealing reliability of the control valve. A split control valve stem and needle valve structure without static leakage is adopted to solve the problem of high-pressure fuel leakage at the axial sealing surface of the needle valve pair and the control piston pair in the traditional electronically controlled fuel injector. At the same time, the structural design of the pressure storage chamber and the control valve stem of the fuel injector of the present invention, as well as the connection structure of the control valve stem and the needle valve, apply the traditional pressure stabilizing effect of the top pressure storage chamber to the needle valve force surface, which can alleviate the pressure drop caused by rapid fuel injection and greatly improve the multi-cycle injection consistency of the common rail fuel injector.

[0040] Working principle:

[0041] High-pressure fuel enters the T-shaped pressure accumulator chamber from the oil inlet joint on the control block, and enters the internal cavity of the injector through the oil passage between the injector body and the control block. When the solenoid valve of the injector is not energized, the core rod presses the sealing steel ball tightly against the control valve seat under the preload force of the electromagnet spring. At this time, the pressure of the control chamber and the pressure accumulator chamber (middle hole pressure accumulator chamber) inside the injector body is balanced, and the valve core of the needle valve is pressed tightly against the nozzle seat surface by the preload force of the return spring. The valve core cannot be lifted, and the needle valve is in a closed state. At this time, the injector does not spray oil. Since the cavity below the sealing steel ball of this injector is a high-pressure cavity and there is no low-pressure area, there is no static leakage when the injector does not spray oil, that is, there is no invalid oil return.

[0042] When the solenoid valve is energized, the solenoid valve generates electromagnetic force and overcomes the preload force of the electromagnetic spring to suck up the armature. The armature also drives the core rod upward, and the sealing steel ball opens under the action of the hydraulic pressure. At this time, the fuel in the control chamber leaks through the oil return hole of the control valve seat, and the pressure in the control chamber drops rapidly. The control valve stem moves upward, thereby driving the valve core of the needle valve to lift up, and the needle valve is in an open state. At this time, the injector starts to spray fuel. When the solenoid valve is closed, the fuel pressure in the control chamber rises rapidly through the flow supplement of the oil inlet hole of the control valve seat. The control valve stem moves downward under the action of the hydraulic pressure in the control chamber. The valve core of the needle valve is connected to the control valve stem with the help of a transition block. Therefore, the valve core is seated under the action of the control valve stem, and the pressure at both ends is balanced again, thereby closing the injector to complete the injection process.

[0043] The present invention creates a solenoid valve of the fuel injector that is integrated into the control block at the top of the fuel injector body, reducing electromagnetic interference, and adopts a transverse built-in T-type pressure chamber structure above the fuel injector to form multiple pressure storage pipe sections that are flexibly arranged in sections, eliminating the integral common rail pipe, and reducing the installation and layout requirements of the common rail system itself, making the layout of the common rail system on the engine more flexible, and can be applied to distributed common rail systems. In addition to the transverse T-type pressure storage chamber above the fuel injector, a central hole pressure storage chamber is designed on the periphery of the control valve stem of the fuel injector, and an independent space is also provided between the valve core of the needle valve and the control valve stem, which not only provides a stable inlet boundary condition for the oil inlet throttling hole and improves the stability of the needle valve control, but also reduces the influence of the previous injection on the subsequent injection, improves the fuel injector's ability to inject multiple times and the accuracy of oil quantity control, thereby greatly improving the stability of the fuel injector's operation.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A large flow T-type pressure accumulator common rail injector, characterized in that: It includes an injector body and a control block installed on a compression sleeve, the control block is located at the upper end of the injector body, and a needle valve is installed at the lower end of the injector body; the needle valve includes a valve body and a valve core, a transition block is provided between the valve body and the injector body, and the transition block is tightly fitted with the injector body and the valve body respectively; a limit block is provided at the upper end of the valve core, a groove for accommodating the limit block is provided on the upper end surface of the valve body, and an independent cavity is formed between the limit block and the transition block; A middle hole pressure storage chamber is provided in the injector body, a control valve stem is installed in the middle hole pressure storage chamber, and the middle hole pressure storage chamber is provided with an upper accommodating section, a middle narrow mouth section and a lower accommodating section from top to bottom; an upper limit piece is provided at one end of the control valve stem in the upper accommodating chamber, and a lower limit piece is provided at one end of the control valve stem in the lower accommodating chamber; a coupling sleeve is provided in the lower accommodating chamber, the coupling sleeve is in clearance with the control valve stem, and a compression spring is provided between the coupling sleeve and the lower limit piece; A small diameter section is provided in the middle of the control valve stem, the upper end of the small diameter section is higher than the top of the middle narrow section, and the lower end is higher than the bottom of the middle narrow section, so that a variable cross-section cavity is formed between the middle hole pressure storage cavity and the control valve stem. The change rule of the variable cross-section cavity structure from top to bottom is: the cross section of the variable cross-section cavity first changes from large to small, and then changes from small to large; the oil chamber in the valve body is connected with the middle hole pressure storage cavity through the through hole of the transition block; The control block is equipped with a solenoid valve, a clamping nut and a control valve seat from top to bottom. The lower end of the armature of the solenoid valve is provided with a core rod, the upper end of which is clamped by an electromagnetic spring, and the lower end of which passes through a clamping nut, which is used to control the matching relationship between the sealing steel ball and the control valve seat, thereby realizing the on-off control of the oil return hole of the control valve seat; the clamping nut is screwed on the control block and clamps the control valve seat to the control block; A mounting hole is provided at the lower end of the control valve seat, the upper end of the control valve stem is inserted into the mounting hole and slidably cooperates with the control valve seat, a return spring is provided between the limiter and the control valve seat, and a control cavity is formed between the control valve stem and the bottom of the mounting hole of the control valve seat; a transition cavity is provided between the injector body and the control block, and the T-shaped pressure storage cavity on the control block and the oil inlet hole of the control valve seat are both connected to the transition cavity.

2. A large flow T-type accumulator common rail injector according to claim 1, characterized in that: The compression spring is mounted on the control valve stem.

3. A large flow T-type accumulator common rail injector according to claim 1, characterized in that: The return spring is mounted on the control valve stem.

4. A large flow T-type accumulator common rail injector according to claim 1, characterized in that: The needle valve is fixed to the injector body through the nozzle cap.

5. A large flow T-type accumulator common rail injector according to claim 4, characterized in that: The nozzle cap is threaded onto the injector body.

6. A large flow T-type accumulator common rail injector according to claim 1, characterized in that: A sealing element is arranged between the control block and the compression sleeve.

7. A large flow T-type accumulator common rail injector according to claim 1, characterized in that: A conical groove is arranged on the upper end surface of the control valve seat, and a sealing conical surface is formed at the junction of the conical groove and the oil return hole.

8. A large flow T-type accumulator common rail injector according to claim 1, characterized in that: The valve core lift of the needle valve is 0.45±0.01mm.

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