Volume variable structure of control cavity of common rail oil injector

Abstract

The invention provides a common rail oil injector control cavity volume variable structure which is composed of a needle valve sleeve, a needle valve, a needle valve spring, an oil nozzle tightening cap, a needle valve body, an oil injector body, a pressing plate, a control ball valve and a sliding valve, the needle valve sleeve and the needle valve are matched in a matching mode, and the needle valve sleeve and the pressing plate jointly form an oil injector control cavity; the control cavity comprises a first inner cavity and a second inner cavity, a sliding plate is arranged in the first inner cavity, the guide diameter of the sliding plate is larger than that of the needle valve, the first inner cavity is communicated with the high-pressure oil inlet channel through an oil inlet hole, and high-pressure fuel oil contained in the high-pressure cavity is supplemented to the first inner cavity through the high-pressure oil inlet channel and the oil inlet hole; and the control ball valve is controlled to be opened, and high-pressure fuel oil in the first inner cavity flows to an oil return channel formed in the oil injector body through the oil outlet hole. The volume of the control cavity is increased in the ascending process of the needle valve, oil pressing of the needle valve is reduced, the volume of the control cavity is reduced in the descending process of the needle valve, the oil pumping effect of the needle valve is reduced, and the effect of increasing the opening speed and the closing speed of the needle valve at the same time is achieved.

Description

Technical Field

[0001] This application belongs to the technical field of high-pressure common rail systems, and particularly relates to a variable control chamber volume structure for a common rail injector. Background Art

[0002] The common rail injector controls the fuel pressure in the control chamber by controlling the opening and closing of the solenoid valve, and uses the change in the control chamber pressure to control the movement of the needle valve, and finally realizes the control of the fuel injection process of the injector. With the development of engine technology, the required fuel injection volume of the injector is getting larger and larger, and thus it is required to increase the opening and closing speed of the needle valve, reduce the throttling action time of the nozzle sealing seat surface, and realize the improvement of the fuel injection volume under the condition that the fuel injection duration remains unchanged or even decreases.

[0003] However, generally, the volume of the control chamber of the common rail injector is only related to the movement of the needle valve during the fuel injection process. During the process of the needle valve opening for fuel injection, it will cause the volume of the control chamber to decrease, resulting in an increase in the control chamber pressure, an increase in the hydraulic resistance for the needle valve to open, and restricting the rapid opening of the needle valve. During the process of the needle valve closing for fuel injection, it will cause the volume of the control chamber to increase, resulting in a decrease in the control chamber pressure, a decrease in the hydraulic power for the needle valve to close, and restricting the rapid closing of the needle valve. This problem becomes more and more serious with the need for rapid opening and rapid closing of the needle valve. Summary of the Invention

[0004] In view of this, this application aims to propose a variable control chamber volume structure for a common rail injector, which realizes the change of the control chamber volume through the movement of two pairs of parts with different diameters, so as to simultaneously meet the requirements of volume increase when the needle valve opens and volume decrease when the needle valve closes.

[0005] To achieve the above object, the technical solution of this application is realized as follows: This application provides a variable control chamber volume structure for a common rail injector. This structure is composed of a needle valve sleeve, a needle valve, a needle valve spring, a nozzle nut, a needle valve body, an injector body, a pressure plate, a control ball valve, and a spool valve. Among them, the needle valve sleeve, the needle valve, the needle valve spring, and the needle valve spring washer are correspondingly installed inside the high-pressure chamber formed inside the injector body. The pressure plate is arranged on the injector body. The nozzle nut is arranged on the injector body and presses the needle valve body against the lower end face of the injector body. The needle valve spring is sleeved on the needle valve and presses the needle valve sleeve and the needle valve against the sealing end faces of the pressure plate and the needle valve body respectively. The needle valve sleeve and the needle valve are in paired fit and jointly form the control chamber of the injector; The control chamber includes a first inner chamber and a second inner chamber. A slide plate is installed in the first inner chamber. The slide plate is used to isolate the first inner chamber from the second inner chamber, and the guiding diameter of the slide plate is larger than that of the needle valve. The first inner chamber is communicated with the high-pressure oil inlet passage through an oil inlet hole. The high-pressure fuel contained in the high-pressure chamber is supplied to the first inner chamber through the high-pressure oil inlet passage and the oil inlet hole. When the control ball valve is controlled to open, the high-pressure fuel in the first inner chamber flows through the oil outlet hole to the oil return passage provided in the injector body.

[0006] Further, the upper end of the needle valve spring presses the needle valve sleeve against the lower end face of the pressure plate. The lower end of the needle valve spring presses the needle valve against the sealing conical surface of the needle valve body through the needle valve spring pad, and the needle valve spring pad is fitted onto the needle valve.

[0007] Further, the slide plate and the needle valve sleeve are a matched pair of parts.

[0008] Further, the diameter of the first inner chamber is larger than that of the second inner chamber, and the cross section of the second inner chamber is in a convex shape.

[0009] Further, the needle valve and the slide plate are hydraulically connected, and the movement of the needle valve lags behind that of the slide plate.

[0010] Further, it further includes a slide plate spring. The slide plate spring is installed in the first inner chamber and presses the slide plate against the upper end face of the second inner chamber.

[0011] Compared with the prior art, the variable control chamber volume structure of the common rail injector described in this application has the following beneficial effects: The variable control chamber volume structure of the common rail injector described in this application realizes the transformation of the control chamber volume from being unfavorable for the movement of the needle valve to being favorable for the movement of the needle valve through the linkage of parts with different diameters, improves the rapid response of the opening and closing of the needle valve, and has high versatility. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The drawings forming a part of this application are used to provide a further understanding of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation to this application. In the drawings: Figure 1 is a schematic diagram of a variable control chamber volume structure of a common rail injector according to an embodiment of this application; Figure 2 is a schematic diagram of the detailed structure of the first part of a variable control chamber volume structure of a common rail injector according to an embodiment of this application; Figure 3 is an enlarged schematic diagram of the detailed structure of the first part according to an embodiment of this application.

[0013] Description of Reference Numerals: 1 - Needle valve sleeve; 2 - Needle valve; 3 - Needle valve spring; 4 - Needle valve spring washer; 5 - Nozzle nut; 6 - Needle valve body; 7 - High - pressure chamber; 8 - Injector body; 9 - Inlet oil passage; 10 - Pressure plate; 11 - Control ball valve; 12 - Return oil passage; 13 - Slide valve spring; 14 - Inlet oil hole; 15 - High - pressure inlet oil passage; 16 - Lower cavity; 17 - Upper cavity; 18 - Slide plate; 19 - First inner cavity; 20 - Outlet oil hole; 21 - Second inner cavity; 22 - Volume chamber. Detailed Embodiment

[0014] To make the objectives, technical solutions and advantages of the present application more clear and understandable, the following further elaborates on the present application in detail with reference to specific embodiments and the attached drawings.

[0015] It should be noted that unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present application should have the ordinary meanings understood by those with ordinary skills in the field to which the present application belongs. The "first", "second" and similar terms used in the embodiments of the present application do not indicate any order, quantity or importance, but are only used to distinguish different components. The terms such as "including" or "comprising" mean that the elements or objects appearing before this word cover the elements or objects listed after this word and their equivalents, without excluding other elements or objects. The terms such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The terms such as "upper", "lower", "left", "right" are only used to represent relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0016] Please refer to Figure 1 and Figure 2 As shown, this embodiment provides a variable - volume structure for the control chamber of a common - rail injector. This structure consists of a needle valve sleeve 1, a needle valve 2, a needle valve spring 3, a nozzle nut 5, a needle valve body 6, an injector body 8, a pressure plate 10, a control ball valve 11, and a slide valve. Among them, the needle valve sleeve 1, the needle valve 2, the needle valve spring 3, and the needle valve spring washer 4 are correspondingly installed inside the high - pressure chamber 7 formed within the injector body 8. The pressure plate 10 is disposed on the injector body 8. The nozzle nut 5 is disposed on the injector body 8 and presses the needle valve body 6 against the lower end face of the injector body 8. The needle valve spring 3 is sleeved on the needle valve 2 and presses the needle valve sleeve 1 and the needle valve 2 against the sealing end faces of the pressure plate 10 and the needle valve body 6 respectively. The needle valve sleeve 1 and the needle valve 2 are a matched pair and jointly form the control chamber of the injector with the pressure plate 10; The control chamber includes a first inner cavity 19 and a second inner cavity 21. A slide plate 18 is installed in the first inner cavity 19. The slide plate 18 is used to isolate the first inner cavity 19 from the second inner cavity 21, and the guiding diameter of the slide plate 18 is greater than the guiding diameter of the needle valve 2. The first inner cavity 19 is communicated with the high-pressure oil inlet passage 15 through an oil inlet hole 14. The high-pressure fuel contained in the high-pressure chamber 7 is replenished to the first inner cavity 19 through the high-pressure oil inlet passage 15 and the oil inlet hole 14. When the control ball valve 11 is manipulated to open, the high-pressure fuel in the first inner cavity 19 flows through the oil outlet hole 20 to the oil return passage 12 provided in the injector body 8.

[0017] Specifically, in this embodiment, the present application utilizes the diameter difference between the slide plate 18 and the needle valve 2 to realize an increase in the volume of the control chamber during the upward movement of the needle valve 2, reducing the "oil pressing" of the needle valve 2, and a decrease in the volume of the control chamber during the downward movement of the needle valve 2, reducing the "oil pumping" of the needle valve 2, so as to achieve the effect of simultaneously increasing the opening and closing speeds of the needle valve 2.

[0018] In some embodiments, the upper end of the needle valve spring 3 presses the needle valve 2 sliding sleeve tightly against the lower end face of the pressure plate 10. The lower end of the needle valve spring 3 presses the needle valve 2 tightly against the sealing conical surface of the needle valve body 6 through the needle valve spring 3 washer, and the needle valve spring 3 washer is fitted onto the needle valve 2.

[0019] In some embodiments, the slide plate 18 and the needle valve sleeve 1 are paired parts. The needle valve 2 is hydraulically connected to the slide plate 18, and the movement of the needle valve 2 lags behind the movement of the slide plate 18. The diameter of the first inner cavity 19 is greater than the diameter of the second inner cavity 21, and the cross-section of the second inner cavity 21 is a convex-shaped surface.

[0020] Specifically, in this embodiment, as Figure 3 shown, the second inner cavity 21 is composed of an upper cavity 17 and a lower cavity 16. When both the slide plate 18 and the needle valve 2 move upward, the volumes of the lower cavity 16 and the first inner cavity 19 decrease, and the decrease value is equal to the volume cavity 22 formed on the lower end face of the slide plate 18. Since the guiding diameter of the slide plate 18 is greater than the guiding diameter of the needle valve 2, when the slide plate 18 and the needle valve 2 have the same displacement, the decrease value of the volume of the lower cavity 16 is less than the volume cavity 22, comprehensively resulting in an increase in the volume of the second inner cavity 21. By the same token, when both the slide plate 18 and the needle valve 2 move downward, the volume of the second inner cavity 21 decreases comprehensively.

[0021] In other words, during the opening stage of the needle valve 2, the slide plate 18 is caused to move upward, and the volume vacated below the slide plate 18 is greater than the volume occupied by the upward movement of the needle valve 2, realizing the function of increasing the volume of the control chamber when the needle valve 2 moves upward. By the same token, during the closing stage of the needle valve 2, the volume occupied by the downward movement of the slide plate 18 is greater than the volume vacated by the downward movement of the needle valve 2, realizing the function of decreasing the volume of the control chamber when the needle valve 2 moves downward. During the fuel injection stage of the injector, it is required that the needle valve 2 opens quickly, which will cause the volume of the second inner cavity 21 to decrease rapidly, and then cause the fuel pressure in the second inner cavity 21 to increase, reducing the opening speed of the needle valve 2. During the opening process of the needle valve 2, increasing the volume of the second inner cavity 21 is beneficial to slowing down the compression effect of the needle valve 2 on the second inner cavity 21, and then improving the opening speed of the needle valve 2. For the same reason, during the closing process of the needle valve 2, reducing the volume of the second inner cavity 21 is beneficial to slowing down the fuel pumping effect of the needle valve 2 on the second inner cavity 21, and then improving the closing speed of the needle valve 2.

[0022] The upward movement of the needle valve 2 is blocked by the lower end surface of the upper cavity 17, that is, the distance between the needle valve 2 and the lower end surface of the upper cavity 17 is the maximum lift of the needle valve 2. The upward movement of the slide plate 18 will be blocked by the lower end surface of the pressure plate 10, that is, the distance between the slide plate 18 and the lower end surface of the pressure plate 10 is the maximum lift of the slide plate 18. In this embodiment, it is required that the maximum lift of the slide plate 18 is greater than the maximum lift of the needle valve 2.

[0023] In some embodiments, it further includes a slide plate spring 13, which is installed in the first inner cavity 19 and presses the slide plate 18 against the upper end surface of the second inner cavity 21.

[0024] In the embodiment, for the existing common rail injector with a spool sleeve structure, the present application only needs to adjust the structure of the needle valve sleeve 1, add the slide plate 18 and the slide plate spring 13, or cancel the slide plate spring 13, that is, only add the slide plate 18 alone, which can realize the change of the control cavity volume to simultaneously meet the requirements of volume increase when the needle valve 2 opens and volume decrease when the needle valve 2 closes, and has high versatility.

[0025] The working process of the common rail injector applying this variable control cavity volume structure is as follows: The solenoid valve is energized to control the ball valve 11 to open, and the high-pressure fuel in the first inner cavity 19 flows through the oil outlet hole 20 to the oil return channel 12 of the injector body 8. The reduction of the fuel pressure in the first inner cavity 19 caused by the opening of the ball valve 11 causes the high-pressure fuel in the high-pressure cavity 7 inside the injector to replenish the first inner cavity 19 through the high-pressure inlet channel 15 and the oil inlet hole 14 of the needle valve sleeve 1. Since the oil outlet flow rate of the oil outlet hole 20 is greater than the oil inlet flow rate of the oil inlet hole 14 of the needle valve sleeve 1, the fuel pressure in the first inner cavity 19 still decreases.

[0026] As the high-pressure fuel in the high-pressure cavity 7 inside the injector replenishes the first inner cavity 19, the fuel pressure in the high-pressure cavity 7 inside the injector decreases, and the high-pressure fuel in the fuel rail starts to replenish the high-pressure cavity 7 inside the injector through the oil inlet channel 9 of the injector body 8, causing the fuel pressure in the high-pressure cavity 7 inside the injector to drop slightly.

[0027] The fuel pressure in the first inner cavity 19 decreases, while the fuel pressure in the second inner cavity 21 remains unchanged. As a result, the hydraulic force acting on the upper end face of the slide plate 18 gradually becomes smaller than that on the lower end face, and the slide plate 18 starts to move upward against the spring preload of the slide plate spring 13.

[0028] During the upward movement of the spool valve, the volume of the first inner cavity 19 decreases, and a volume cavity 22 is formed on the lower end face of the slide plate 18. As the volume cavity 22 gradually forms and merges with the second inner cavity 21, the volume of the second inner cavity 21 gradually increases. Without an external oil circuit for oil replenishment, the fuel pressure in the second inner cavity 21 decreases as the volume increases.

[0029] As the pressure in the second inner cavity 21 decreases, the pressure in the lower cavity 16 of the second inner cavity 21 decreases, and the hydraulic force acting on the needle valve 2 decreases. Since the pressure drop in the internal high-pressure cavity 7 is small, the needle valve 2 overcomes the combined force of the spring preload of the needle valve spring 3 and the hydraulic force in the internal high-pressure cavity 7 and starts to open for fuel injection. During the upward movement of the needle valve 2, the volume of the lower cavity 16 of the second inner cavity 21 decreases. Since the diameter of the slide plate 18 is larger than that of the needle valve 2, the volume cavity 22 formed on the lower end face of the slide plate 18 is larger than the decrease in the volume of the lower cavity 16 of the second inner cavity 21. Since the volume of the upper cavity 17 of the second inner cavity 21 remains unchanged, during the upward movement stage of the needle valve 2, the increase in the second inner cavity 21 will reduce the oil pressure effect of the needle valve 2 on the second inner cavity 21 and increase the opening speed of the needle valve 2.

[0030] When the solenoid valve is de-energized, the control ball valve 11 closes, and the oil inlet hole 14 of the needle valve sleeve 1 continues to replenish oil to the first inner cavity 19. The fuel pressure in the first inner cavity 19 starts to recover. After overcoming the hydraulic force in the second inner cavity 21, the slide plate 18 starts to move downward, causing the volume of the second inner cavity 21 to decrease. The fuel pressure in the second inner cavity 21 increases as the volume decreases. After overcoming the hydraulic force in the internal high-pressure cavity 7 of the injector body 8, the needle valve 2 starts to move downward, and the injector starts to stop fuel injection. The downward movement of the slide plate 18 causes the volume of the volume cavity 22 to decrease, and the downward movement of the needle valve 2 causes the volume of the lower cavity 16 to increase. Since the diameter of the slide plate 18 is larger than that of the needle valve 2, the decrease in the volume of the volume cavity 22 is larger than the increase in the volume of the lower cavity 16 of the second inner cavity 21. Since the volume of the upper cavity 17 of the second inner cavity 21 remains unchanged, during the downward movement stage of the needle valve 2, the decrease in the second inner cavity 21 will reduce the oil pumping effect of the needle valve 2 on the second inner cavity 21 and increase the closing speed of the needle valve 2.

[0031] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered by the scope of the claims and the description of the present invention.

[0032] Embodiments of the present application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present application shall be included within the protection scope of the present application.

Claims

1. A common rail injector control chamber volume variable structure, characterized in that: The structure is composed of a needle valve sleeve, a needle valve, a needle valve spring, a nozzle cap, a needle valve body, a fuel injector body, a pressure plate, a control ball valve, and a sliding valve, wherein the needle valve sleeve, the needle valve, the needle valve spring, and the needle valve spring pad are correspondingly installed in a high-pressure chamber formed inside the fuel injector body, the pressure plate is arranged on the fuel injector body, the nozzle cap is arranged on the fuel injector body, and presses the needle valve body against the lower end surface of the fuel injector body, the needle valve spring sleeve is arranged on the needle valve, and presses the needle valve sleeve and the needle valve against the sealing end surfaces of the pressure plate and the needle valve body respectively, the needle valve sleeve and the needle valve are matched as a pair, and together with the pressure plate form a control chamber of the fuel injector; The control cavity includes a first inner cavity and a second inner cavity, a slide plate is installed in the first inner cavity, the slide plate is used to separate the first inner cavity from the second inner cavity, and the guide diameter of the slide plate is larger than the guide diameter of the needle valve, the first inner cavity is connected to the high-pressure oil inlet passage through the oil inlet hole, and the high-pressure fuel contained in the high-pressure cavity is replenished to the first inner cavity through the high-pressure oil inlet passage and the oil inlet hole; The control ball valve is manipulated to open, and the high-pressure fuel in the first inner cavity flows to the oil return passage provided in the injector body through the oil outlet hole.

2. The common rail injector control chamber volume variable structure according to claim 1, characterized in that: The upper end of the needle valve spring presses the needle valve sleeve against the lower end surface of the pressure plate, and the lower end of the needle valve spring presses the needle valve against the sealing cone surface of the needle valve body through the needle valve spring pad, and the needle valve spring pad is embedded in the needle valve.

3. The common rail injector control chamber volume variable structure according to claim 1, characterized in that: The slide plate and the needle valve sleeve are matched as a pair.

4. The common rail injector control chamber volume variable structure according to claim 1, characterized in that: The diameter of the first inner cavity is greater than the diameter of the second inner cavity, and the cross-section of the second inner cavity is a convex-shaped surface.

5. The common rail injector control chamber volume variable structure according to claim 1, characterized in that: The needle valve is hydraulically connected to the slide plate, and the movement of the needle valve lags behind the movement of the slide plate.

6. The common rail injector control chamber volume variable structure according to claim 1, characterized in that: It also includes a slide plate spring, which is installed in the first inner cavity and presses the slide plate against the upper end surface of the second inner cavity.

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