A control valve for high-pressure common rail fuel injectors

Abstract

The utility model belongs to fuel injection device technical field relates to a control valve for high pressure common rail fuel injector, including valve body, valve rod, armature and bush, armature is located in the upper end of valve rod, is provided with armature containing chamber and valve cavity in the valve body, and armature containing chamber and valve cavity coaxial arrangement are arranged, bush has the valve rod moving cavity that penetrates along the axial direction, valve rod is set up in the valve rod moving cavity and can axially move, and the outer wall of bush and the inner wall of valve cavity form the outer balance annular chamber, and the inner wall of bush and valve rod form the inner balance annular chamber, the pressure balance oil return line is seted up on the valve body, and the pressure balance oil return line is communicated with the outer balance annular chamber and the inner balance annular chamber simultaneously. The utility model has solved the problem of the existing technology that the radial fuel pressure that the inner wall of valve body bears is different at different heights, forms pressure gradient from top to bottom, and further leads to valve cavity deformation, causes the problem of the increase of fit clearance, appears internal leakage.

Description

Technical Field

[0001] This utility model relates to a control valve for a high-pressure common rail injector, belonging to the technical field of fuel injection devices. Background Technology

[0002] High-pressure common rail injectors are key components of modern diesel engines. The control valve is a key component of the injector, responsible for precisely controlling the opening and closing of the injector needle valve. Its response speed and sealing reliability are crucial to the performance of the injector.

[0003] In existing technologies, hydraulic balancing designs are commonly used to improve the response speed of control valves. For example, prior art document CN 212376770 U discloses a control valve for a high-pressure common rail injector, which features a pressure balancing section on the valve stem and introduces high-pressure fuel into the pressure balancing chamber through a pressure balancing return oil circuit. This causes the hydraulic pressure on the upper and lower end faces of the valve stem to cancel each other out, thereby reducing the resistance to valve stem movement. In another prior art document CN 110017230 A, a complex oil circuit, such as an inclined channel between the armature and the armature seat, is used to rapidly change the pressure in the relevant chambers when the control valve actuates, thereby achieving hydraulic actuation of the needle valve.

[0004] The core balancing principle of the aforementioned prior art lies in the fact that, through an internal oil passage, high-pressure fuel at one end of the armature is led to the other end, forming a force in the opposite direction to the main hydraulic pressure. When the magnitudes of these two forces reach equilibrium due to the difference in their effective action areas, the external force (such as electromagnetic force) required to drive the valve core can be significantly reduced, thereby achieving rapid action.

[0005] However, existing technical solutions have many drawbacks: First, the structural deformation of the valve body under ultra-high pressure is a significant problem. In structures such as CN 212376770 U, the diameter of different sections of the cavity used to install the valve stem within the valve body is inconsistent. Typically, the diameter of the pressure balancing oil cavity is larger, while the diameter of the lower return oil guide cavity is smaller. This results in differences in radial fuel pressure at different heights on the inner wall of the valve body, forming a pressure gradient from top to bottom. After long-term exposure to extreme cyclic pressure shocks exceeding 2000 Bar, the valve body material undergoes irreversible plastic deformation due to fatigue, and the cavity gradually evolves into... Figure 1The tapered shape, wider at the top and narrower at the bottom, disrupts the original precision fit between the valve stem and body, leading to poor sealing and increased internal leakage. This not only wastes fuel and reduces fuel efficiency but also decreases the injector's injection volume and control precision. Simultaneously, the abnormally increased leaking fuel flows into the low-pressure return system, causing increased return flow and temperature. Higher return temperatures accelerate fuel thermal degradation, generating more gum and carbon deposits within the system, further exacerbating wear and clogging risks, creating a vicious cycle that restricts the injector's reliability and lifespan.

[0006] Secondly, in control valves employing multi-component combined valve bodies, the sealing reliability of the mating surfaces of each component is insufficient. For example, in the structure disclosed in prior art document CN 110017230 A, the armature seat and valve seat are two independent parts, pressed together by the axial preload provided by the injector cap or body. However, the end face area of ​​these two parts contacting each other to achieve a seal is relatively large, resulting in a relatively low actual pressure (i.e., sealing specific pressure) on the sealing surface under the same axial preload. When the control valve is subjected to extremely high fuel pressure, the hydraulic pressure acting on the sealing surface may exceed this sealing specific pressure, causing slight separation of the sealing surface, thereby triggering fuel leakage from the mating interface between the armature seat and the valve seat. Utility Model Content

[0007] The purpose of this utility model is to provide a new technical solution to improve or solve the technical problems existing in the prior art as described above.

[0008] The technical solution provided by this utility model is as follows: A control valve for a high-pressure common rail injector includes a valve body, a valve stem, and an armature. The armature is connected to the upper end of the valve stem. The valve body is provided with an armature receiving cavity and a valve cavity, which are coaxially arranged. It also includes a bushing disposed within the valve cavity. The bushing has an axially penetrating valve stem moving cavity. The valve stem is axially movable within the valve stem moving cavity. An outer balance annular cavity is formed between the outer wall of the bushing and the inner wall of the valve cavity, and an inner balance annular cavity is formed between the inner wall of the bushing and the valve stem. A pressure balance return oil passage is provided within the valve body, which is simultaneously connected to the outer balance annular cavity and the inner balance annular cavity.

[0009] Furthermore, the lower end face of the control valve body is provided with a main sealing boss, a first auxiliary sealing boss, a second auxiliary sealing boss, and a third auxiliary sealing boss, wherein the first auxiliary sealing boss and the second auxiliary sealing boss are arranged symmetrically; the main sealing boss and the third auxiliary sealing boss are both located on the extension line of the axis of symmetry of the first auxiliary sealing boss and the second auxiliary sealing boss, and the center points of the first auxiliary sealing boss, the second auxiliary sealing boss, and the third auxiliary sealing boss are arranged at the three vertices of an isosceles triangle.

[0010] The beneficial effect of adopting the above-mentioned further solution is that, by replacing the traditional large-area end-face sealing with a multi-point small-area contact sealing with the main sealing boss as the core and three auxiliary bosses as stable supports, the pressure acting on the sealing boss is increased under the same installation preload, ensuring that the sealing interface remains tightly fitted and preventing leakage. At the same time, the triangularly distributed auxiliary bosses form a stable support, effectively preventing the mating surface from warping under stress.

[0011] Furthermore, the lower end face of the valve body is provided with multiple oil passages, and the outer contour of the main sealing boss surrounds the oil passages.

[0012] Furthermore, the outer contours of the first auxiliary sealing boss, the second auxiliary sealing boss, and the third auxiliary sealing boss are all crescent-shaped.

[0013] Furthermore, the first auxiliary sealing boss, the second auxiliary sealing boss, and the third auxiliary sealing boss are respectively disposed on the edge of the lower end face of the valve body.

[0014] Furthermore, the bushing is interference-fitted with the valve body.

[0015] Furthermore, the top surfaces of the main sealing boss, the first auxiliary sealing boss, the second auxiliary sealing boss, and the third auxiliary sealing boss are all provided with chamfers or rounded corners.

[0016] The beneficial effect of adopting the above-mentioned further solution is that it eliminates sharp edges, prevents scratching or cutting of the surfaces of mating parts during the clamping process, and ensures the best sealing effect.

[0017] Furthermore, the valve stem moving chamber within the bushing includes a sealing chamber, a pressure balancing oil chamber, and a return oil guide chamber arranged coaxially from top to bottom, wherein the inner diameter of the pressure balancing oil chamber is larger than the inner diameter of the return oil guide chamber; the valve stem includes a sealing end, a pressure balancing section, and a return oil guide section arranged coaxially from top to bottom, wherein the diameter of the pressure balancing section is smaller than the diameter of the return oil guide section.

[0018] The beneficial effect of adopting the above-mentioned further scheme is that the cooperation between the pressure balancing oil chamber and the valve stem pressure balancing section provides space for radial hydraulic balancing.

[0019] Furthermore, the wall thickness of the bushing is 15% to 25% of its outer diameter.

[0020] Furthermore, the axis of the pressure balance return oil circuit forms an angle of 30° to 60° with the axis of the valve stem.

[0021] Compared with the prior art, the technical solution provided by this utility model has the following beneficial effects: The control valve of this utility model, by setting a bushing, forms a dual pressure balance structure between the valve stem and the valve body, consisting of an outer and inner balanced annular cavity. Fuel is simultaneously introduced into these two annular cavities through the pressure balance return oil path, thereby forming radial hydraulic pressure balance on both the inner and outer sides of the bushing. This reduces the risk of plastic deformation of the valve cavity due to high pressure on one side, i.e., the risk of the cavity deforming into a cone shape that is larger at the top and smaller at the bottom. It solves the problem in the prior art where the radial fuel pressure difference at different heights on the inner wall of the valve body creates a pressure gradient from top to bottom, leading to valve cavity deformation, increased clearance, and internal leakage. Attached Figure Description To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of an existing valve cavity that undergoes plastic deformation due to pressure. Figure 2 This is a three-dimensional structural diagram of the valve body of the present invention; Figure 3 This is a top view of the valve body of the present invention; Figure 4 This is a schematic diagram of the lower end face of the valve body of the present invention; Figure 5 This is a cross-sectional view of the valve body of the present invention; Figure 6 For the present invention Figure 5 Enlarged view of part B; Figure 7 For the present invention Figure 5 A three-dimensional sectional view; Figure 8 For the present invention Figure 3 Sectional view along axis AA; Figure 9 This is a schematic diagram of the mechanism by which the valve body of the present invention is installed above the fuel injector; Figure 10 This is a comparison diagram of the contact stress distribution between the present invention and the prior art.

[0023] In the diagram, 1. Valve body; 2. Valve stem; 3. Armature; 4. Armature receiving cavity; 5. Valve cavity; 6. Bushing; 7. Outer balance annular cavity; 8. Inner balance annular cavity; 9. Pressure balance return oil circuit; 10. Main sealing boss; 11. First auxiliary sealing boss; 12. Second auxiliary sealing boss; 13. Third auxiliary sealing boss; 14. Sealing cavity; 15. Pressure balance oil cavity; 16. Return oil guide cavity; 17. Injector; 18. Injector control chamber. Detailed Implementation

[0024] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the objects described and do not imply any priority in order or any specific technical meaning. Furthermore, the concepts of "connection" and "linkage" mentioned in this application, unless otherwise specified, are considered to include both direct connection (linkage) and indirect connection (linkage).

[0025] When interpreting the description of this application, it should be clarified that terms such as "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," indicating directions or positional relationships, are based on the perspective and layout shown in the accompanying drawings. They are intended to facilitate explanation and simplify the description process, and are not absolute limitations on the actual location, construction method, or operating mode of the described device or element. Therefore, these terms should not be construed as restrictive interpretations of the content of this application.

[0026] The principles and features of this utility model are described below with reference to examples. The examples are only used to explain this utility model and are not intended to limit the scope of this utility model.

[0027] like Figures 2-8 As shown, a control valve for a high-pressure common rail injector includes a valve body 1, a valve stem 2, and an armature 3. The armature 3 is connected to the upper end of the valve stem 2. The valve body 1 has an armature receiving cavity 4 and a valve cavity 5, which are connected. The valve cavity 5 extends axially along the valve body 1, and the armature receiving cavity 4 and the valve cavity 5 are coaxially arranged. The valve body 1 also includes a bushing 6 disposed within the valve cavity 5. The bushing 6 has an axially penetrating valve stem moving cavity, and the valve stem 2 is axially movable within the valve stem moving cavity. An outer balancing annular cavity 7 is formed between the outer wall of the bushing 6 and the inner wall of the valve cavity 5, and an inner balancing annular cavity 8 is formed between the inner wall of the bushing 6 and the valve stem 2. A pressure balancing return oil passage 9 is provided within the valve body 1, and the pressure balancing return oil passage 9 is simultaneously connected to the outer balancing annular cavity 7 and the inner balancing annular cavity 8.

[0028] After bushing 6 is installed, high-pressure fuel from pressure balance return oil circuit 9 is simultaneously introduced into the outer balance annular cavity 7 between bushing 6 and valve body 1 and the inner balance annular cavity 8 between bushing 6 and valve stem 2, creating a compensating pressure between bushing 6 and the inner wall of valve cavity 5. High-pressure fuel acts on bushing 6 from both inside and outside, so that the radial hydraulic pressure borne by bushing 6 itself reaches a basic balance. Since the radial force is balanced, the problem of valve cavity 5 being stretched into a cone shape with a larger top and smaller bottom due to high pressure on one side in the traditional design is solved. Therefore, by setting the bushing 6, a dual pressure balance structure of an outer balance annular cavity 7 and an inner balance annular cavity 8 is formed between the valve stem 2 and the valve body 1. Fuel is simultaneously introduced into these two annular cavities through the pressure balance return oil passage 9, thereby forming a radial hydraulic pressure balance on both the inner and outer sides of the bushing 6. This reduces the risk of plastic deformation of the valve cavity 5 due to high pressure on one side, i.e., the risk of the cavity deforming into a conical shape that is larger at the top and smaller at the bottom. This solves the problem in the prior art where the radial fuel pressure on the inner wall of the valve body 1 varies at different heights, forming a pressure gradient from top to bottom, which causes deformation of the valve cavity 5, resulting in increased clearance and internal leakage.

[0029] In addition, in this embodiment, the lower end face of the valve body 1 of the control valve is provided with a main sealing boss 10, a first auxiliary sealing boss 11, a second auxiliary sealing boss 12, and a third auxiliary sealing boss 13; the lower end face of the valve body 1 is also provided with a plurality of oil passages, and the outer contour of the main sealing boss 10 is arranged around the oil passages; the outer contours of the first auxiliary sealing boss 11, the second auxiliary sealing boss 12, and the third auxiliary sealing boss 13 are all crescent-shaped and are respectively provided on the edge of the lower end face of the valve body 1; the first auxiliary sealing boss 11 and the second auxiliary sealing boss 12 are arranged symmetrically; the third auxiliary sealing boss 13 is located on the extension line of the axis of symmetry of the first auxiliary sealing boss 11 and the second auxiliary sealing boss 12, and the center points of the first auxiliary sealing boss 11, the second auxiliary sealing boss 12, and the third auxiliary sealing boss 13 are arranged at the three vertices of an isosceles triangle. By replacing the traditional large-area end-face sealing with a multi-point small-area contact seal centered on the main sealing boss 10 and supported by three auxiliary bosses, the pressure acting on the sealing bosses is increased under the same installation preload, ensuring a tight seal between the sealing interfaces and preventing leakage. Simultaneously, the triangularly distributed auxiliary bosses provide stable support, effectively preventing warping of the mating surfaces under stress. The top surfaces of the main sealing boss 10, the first auxiliary sealing boss 11, the second auxiliary sealing boss 12, and the third auxiliary sealing boss 13 are all chamfered or rounded, eliminating sharp edges and preventing scratching or cutting of the mating surfaces during tightening, thus ensuring optimal sealing performance. By replacing the traditional large-area end-face sealing with a multi-point small-area contact seal centered on the main sealing boss 10 and supported by three auxiliary bosses, the pressure acting on the sealing bosses is increased under the same installation preload, ensuring a tight seal between the sealing interfaces and preventing leakage. Meanwhile, the triangularly distributed auxiliary bosses provide stable support, effectively preventing the mating surface from warping under stress.

[0030] like Figure 9 As shown, the control valve of the present invention is applied inside the fuel injector. The control valve is located above the fuel injector 17. The upper part of the fuel injector 17 is provided with a fuel injector control chamber 18. The lower end face of the control valve is also provided with multiple oil holes. The upper end face of the fuel injector 17 is also provided with oil holes. The oil holes on the lower end face of the control valve are correspondingly connected to the oil holes on the upper end face of the fuel injector 17. The control valve is sealed to the upper end face of the fuel injector 17 through the first auxiliary sealing boss 11, the second auxiliary sealing boss 12 and the third auxiliary sealing boss 13 on the lower end face, and the two are fastened by the cap nut sleeved on the outside of the control valve and the fuel injector 17.

[0031] The sealing boss on the lower end face of the control valve and the area of ​​the upper end face of the fuel injector 17 and the fuel injector control chamber 18 form a sealing surface; while the gap area between the sealing bosses and the position of the oil hole form a connecting path to ensure that the oil flows in the designated channel.

[0032] like Figure 10 As shown in the figure, experimental data visually demonstrates the advantages of this invention over existing technologies in sealing performance. In this figure, the horizontal axis represents the position coordinates, with its zero point located at the center point of the lower end face of the valve body 1; the vertical axis represents the contact stress, which refers to the local stress generated within the material in and around the contact area when two objects come into contact and transmit pressure. The blue curve represents the contact stress distribution between the control valve of this invention and the fuel injector 17, while the green curve represents the existing technology. The comparison shows that in the core sealing area near the high-pressure oil inlet, the end face contact stress of this invention (blue curve) is significantly higher than that of the existing design (green curve) and remains at a high level. This invention, by optimizing the sealing boss structure on the lower end face of the valve body 1, precisely applies the highest contact stress to the most critical sealing path, thereby ensuring sealing reliability.

[0033] In this embodiment, the valve stem moving chamber within the bushing 6 includes a sealing chamber 14, a pressure balancing oil chamber 15, and a return oil guide chamber 16, arranged coaxially from top to bottom. The inner diameter of the pressure balancing oil chamber 15 is larger than the inner diameter of the return oil guide chamber 16. The valve stem 2 includes a sealing end, a pressure balancing section, and a return oil guide section, arranged coaxially from top to bottom. The diameter of the pressure balancing section is smaller than the diameter of the return oil guide section. The cooperation between the pressure balancing oil chamber 15 and the pressure balancing section of the valve stem 2 provides space for radial hydraulic balance.

[0034] The bushing 6 is either interference-fitted to the valve cavity 5 of the valve body 1 or fixedly connected by a retaining pin. The interference fit or retaining pin connection ensures that the bushing 6 is fixed in the valve cavity 5 of the valve body 1, preventing displacement under the impact of high-pressure fuel and the high-frequency movement of the valve stem 2.

[0035] The wall thickness of the bushing 6 is 15% to 25% of its outer diameter. The axis of the pressure balance return oil passage 9 forms an angle of 30° to 60° with the axis of the valve stem 2.

[0036] This embodiment also discloses an injector assembly, including an injector nozzle and a needle valve, and further including the control valve for the high-pressure common rail injector. The needle valve is disposed in the inner cavity of the injector nozzle, and the control valve is disposed at the upper end of the injector nozzle. The lower end face of the valve body 1 of the control valve and the upper end face of the injector nozzle achieve sealed contact through the main sealing boss 10, the first auxiliary sealing boss 11, the second auxiliary sealing boss 12 and the third auxiliary sealing boss 13.

[0037] The oil passage port on the lower end face of the control valve body 1 is aligned and sealed with the corresponding fuel passage inside the injector. When the control valve is applied to the injector assembly, multiple sealing bosses on the lower end face of its valve body 1 form a high-strength sealing connection with the upper end face of the injector, ensuring that high-pressure fuel is transmitted without leakage between the two interfaces. The alignment of the oil passage port ensures that the fuel flows smoothly from the common rail to the injector.

[0038] 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 principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A control valve for a high-pressure common rail injector, characterized in that, The valve body (1), valve stem (2), and armature (3) are included. The armature (3) is connected to the upper end of the valve stem (2). The valve body (1) is provided with an armature receiving cavity (4) and a valve cavity (5), which are coaxially arranged. The valve body (1) is also provided with a bushing (6) disposed in the valve cavity (5). The bushing (6) has a valve stem moving cavity that runs through the axial direction. The valve stem (2) is axially movable in the valve stem moving cavity. An outer balance annular cavity (7) is formed between the outer wall of the bushing (6) and the inner wall of the valve cavity (5). An inner balance annular cavity (8) is formed between the inner wall of the bushing (6) and the valve stem (2). A pressure balance return oil passage (9) is provided in the valve body (1). The pressure balance return oil passage (9) is connected to both the outer balance annular cavity (7) and the inner balance annular cavity (8).

2. The control valve for a high-pressure common rail injector according to claim 1, characterized in that, The lower end face of the valve body (1) of the control valve is provided with a main sealing boss (10), a first auxiliary sealing boss (11), a second auxiliary sealing boss (12) and a third auxiliary sealing boss (13). The first auxiliary sealing boss (11) and the second auxiliary sealing boss (12) are arranged symmetrically. The main sealing boss (10) and the third auxiliary sealing boss (13) are both located on the extension line of the axis of symmetry of the first auxiliary sealing boss (11) and the second auxiliary sealing boss (12). The center points of the first auxiliary sealing boss (11), the second auxiliary sealing boss (12) and the third auxiliary sealing boss (13) are arranged at the three vertices of an isosceles triangle.

3. The control valve for a high-pressure common rail injector according to claim 2, characterized in that, The lower end face of the valve body (1) is also provided with multiple oil passages, and the outer contour of the main sealing boss (10) surrounds the oil passages.

4. The control valve for a high-pressure common rail injector according to claim 2, characterized in that, The outer contours of the first auxiliary sealing boss (11), the second auxiliary sealing boss (12), and the third auxiliary sealing boss (13) are all crescent-shaped.

5. The control valve for a high-pressure common rail injector according to claim 2, characterized in that, The first auxiliary sealing boss (11), the second auxiliary sealing boss (12) and the third auxiliary sealing boss (13) are respectively disposed on the edge of the lower end face of the valve body (1).

6. The control valve for a high-pressure common rail injector according to claim 1, characterized in that, The bushing (6) is interference-fitted with the valve body (1).

7. The control valve for a high-pressure common rail injector according to claim 2, characterized in that, The top surfaces of the main sealing boss (10), the first auxiliary sealing boss (11), the second auxiliary sealing boss (12), and the third auxiliary sealing boss (13) are all provided with chamfers or rounded corners.

8. The control valve for a high-pressure common rail injector according to any one of claims 1 to 7, characterized in that, The valve stem moving chamber inside the bushing (6) includes a sealing chamber (14), a pressure balancing oil chamber (15), and a return oil guide chamber (16) arranged coaxially from top to bottom. The inner diameter of the pressure balancing oil chamber (15) is larger than the inner diameter of the return oil guide chamber (16). The valve stem (2) includes a sealing end, a pressure balancing section, and a return oil guide section arranged coaxially from top to bottom. The diameter of the pressure balancing section is smaller than the diameter of the return oil guide section.

9. The control valve for a high-pressure common rail injector according to any one of claims 1 to 7, characterized in that, The wall thickness of the bushing (6) is 15% to 25% of its outer diameter.

10. The control valve for a high-pressure common rail injector according to any one of claims 1 to 7, characterized in that, The axis of the pressure balance return oil circuit (9) forms an angle of 30° to 60° with the axis of the valve stem (2).

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