Common rail oil injector controlled by three-way valve

Abstract

The utility model belongs to the technical field of oil injectors, and particularly discloses a common rail oil injector controlled by a three-way valve, which comprises an oil injector body, an electromagnetic valve assembly, a switch valve, a metering valve, the three-way valve and a needle valve assembly, a switch hole is formed in the end face, close to the switch valve, of the metering valve. The metering valve is provided with a first control cavity communicated with the switch hole. The three-way valve is provided with a third oil hole communicated with the oil sprayer body, and the third oil hole is communicated with the first control cavity through a third buffer groove and the first buffer groove; the third oil hole is communicated with the second control cavity through the third buffer groove, the first buffer groove and the second buffer groove; the second control cavity is communicated with the first control cavity through the second buffer groove and the first buffer groove; the first buffering groove, the second buffering groove and the third buffering groove are used for buffering flowing stress of fuel oil, so that smooth flowing of the fuel oil in the three-way valve is improved, fatigue damage of the fuel oil to the three-way valve is delayed, and the service life of the fuel injector is prolonged.

Description

Technical Field

[0001] The utility model belongs to the technical field of fuel injectors, and in particular relates to a common rail fuel injector controlled by a three-way valve. Background Art

[0002] With the country's increasing emphasis on environmental protection and the upgrading of emission regulations, fuel injectors, as the fuel atomization mechanism of internal combustion engines, usually use the method of increasing injection pressure to achieve the goal of reducing harmful substance emissions.

[0003] In existing technology, as injector injection pressure increases, the dynamic return and inlet pressures of the three-way valve, which controls the opening and closing speed of the injector needle, also increase. According to fluid mechanics, a greater pressure differential potential energy results in a higher fuel flow rate. This higher flow rate increases the scouring stress on the three-way valve's surface, increasing wear on the inner walls of the valve's oil channels. In particular, it increases the likelihood of cavitation at the oil ports, shortening the life of the injector. Utility Model Content

[0004] The purpose of the utility model is to provide a common rail injector controlled by a three-way valve, which can buffer the flow stress of high-pressure fuel in the three-way valve when the injection pressure of the injector is high, delay the fatigue damage of the high-pressure fuel to the three-way valve, and improve the service life of the injector.

[0005] The purpose of this utility model is achieved through such a technical solution.

[0006] A three-way valve controlled common rail injector comprises: an injector body and a solenoid valve assembly, an on-off valve, a metering valve, a three-way valve and a needle valve assembly arranged in an inner cavity of the injector body from top to bottom;

[0007] The metering valve is provided with a switch hole on the end surface close to the switch valve, and the metering valve is provided with a first control chamber communicated with the switch hole;

[0008] The three-way valve is provided with a third oil hole connected to the injector body. The third oil hole is connected to the first control chamber through the third slow groove and the first slow groove; the third oil hole is connected to the second control chamber through the third slow groove, the first slow groove and the second slow groove; the second control chamber is connected to the first control chamber through the second slow groove and the first slow groove; the first slow groove, the second slow groove and the third slow groove are used to buffer the flow stress of the fuel.

[0009] Preferably, the three-way valve is further provided with a first oil hole and a second oil hole, one end of the first oil hole is connected to the first control chamber through a first slow groove, the other end of the first oil hole is connected to the second control chamber through a second slow groove, and the second oil hole connects the second control chamber and the injector body.

[0010] Preferably, a first slow groove is provided at the top of the three-way valve, the upper end surface of the first slow groove is connected to the first control chamber, the lower end surface of the first slow groove is provided with a connecting portion connected to the first oil hole, and one side of the lower end surface of the first slow groove is connected to the top of the third slow groove.

[0011] Preferably, the switch hole is provided with a first switch hole section and a second switch hole section, the aperture of the second switch hole section is larger than the aperture of the first switch hole section, and the switch valve is used to open or seal the second switch hole section; the aperture of the second switch hole section is larger than the aperture of the first switch hole section.

[0012] Preferably, the sum of the apertures of the first oil hole and the third oil hole is smaller than the aperture of the first switch hole segment, and the aperture of the second oil hole is smaller than the aperture of the first oil hole.

[0013] Preferably, the first oil hole and the third oil hole are both staggered with respect to the switch hole.

[0014] Preferably, the third oil hole is connected to the injector body through the fourth slow groove.

[0015] Preferably, the bottom and top end surfaces of the switch valve are flat, and the metering valve is provided with a sealing surface that cooperates with the switch valve.

[0016] Due to the adoption of the above technical solution, the utility model has the following advantages: when the injector is spraying or taking in oil, the first slow groove, the second slow groove and the third slow groove in the three-way valve reduce the flow stress of the high-pressure fuel, thereby improving the smooth flow of fuel in the three-way valve, delaying fatigue damage to the inner wall of the three-way valve, and thus increasing the service life of the injector. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific embodiments of the present invention, the following briefly introduces the drawings required for use in the specific embodiments. In all the drawings, each element or part is not necessarily drawn according to the actual scale.

[0018] Figure 1 This is a structural diagram of a common rail injector controlled by a three-way valve according to the present invention;

[0019] Figure 2 This is an enlarged schematic diagram of point A.

[0020] Reference numerals:

[0021] 1-metering valve, 11-switch hole, 111-first switch hole section, 112-second switch hole section, 12-first control chamber, 13-sealing surface, 2-switch valve, 3-three-way valve, 31-second control chamber, 32-second oil hole, 33-third oil hole, 34-first slow groove, 341-connecting part, 35-second slow groove, 36-third slow groove, 37-first oil hole, 38-fourth slow groove, 4-injector body, 5-solenoid valve assembly, 6-needle valve assembly. DETAILED DESCRIPTION

[0022] See also Figure 1 and Figure 2 A common rail injector controlled by a three-way valve comprises an injector body 4 and a solenoid valve assembly 5, a switch valve 2, a metering valve 1, a three-way valve 3 and a needle valve assembly 6 arranged in the inner cavity of the injector body 4 from top to bottom; the metering valve 1 is provided with a switch hole 11 on the end face near the switch valve 2, and the metering valve 1 is provided with a first control chamber 12 connected to the switch hole 11; the three-way valve 3 is provided with a third oil hole 33 connected to the injector body 4, and the third oil hole 33 is connected to the first control chamber 12 through a third slow groove 36 and a first slow groove 34; the third oil hole 33 is connected to the second control chamber 31 through the third slow groove 36, the first slow groove 34 and the second slow groove 35; the second control chamber 31 is connected to the first control chamber 12 through the second slow groove 35 and the first slow groove 34; the first slow groove 34, the second slow groove 35 and the third slow groove 36 are used to buffer the flow stress of the fuel. Specifically, the inner cavity of the injector body 4 is provided with a solenoid valve mounting cavity, a metering valve mounting cavity, a three-way valve mounting cavity, and a needle valve mounting cavity from top to bottom. The three-way valve mounting cavity is connected to the oil inlet passage on the injector body 4, and the metering valve mounting cavity is connected to the oil outlet passage on the injector body 4. The metering valve mounting cavity and the oil outlet passage are disconnected or connected to the switch valve 2 via the sealing surface 13, so that the switch valve 2 opens or closes the switch hole 11. The solenoid valve assembly 5 is disposed in the solenoid valve mounting cavity; the three-way valve 3 is disposed in the three-way valve mounting cavity; and the needle valve assembly 6 is disposed in the needle valve cavity.

[0023] In the three-way valve-controlled common rail injector of the present invention, when the injector begins to flow fuel, the on-off valve 2 seals the on-off hole 11. As a result, the high-pressure fuel entering from the third oil hole 33 partially flows through the third slow groove 36 and the first slow groove 34 into the first control chamber 12, and partially flows through the third slow groove 36, the first slow groove 34, and the second slow groove 35 into the second control chamber 31, thereby filling both the first control chamber 12 and the second control chamber 31 with the high-pressure fuel. At this point, the upper portion of the needle valve assembly 6 is subjected to the downward force of the fuel in the second control chamber 31, pressing the needle valve assembly 6 downward, and the injector is in the closed state.

[0024] When the solenoid valve is working, the switch valve 2 is separated from the sealing surface 13, the switch hole 11 is opened, and the fuel in the first control chamber 12 flows to the oil outlet through the switch hole 11. The oil pressure in the first control chamber 12 drops rapidly, and the high-pressure fuel in the second control chamber 31 flows into the first control chamber 12 through the second slow groove 35 and the first slow groove 34, resulting in a decrease in the oil pressure in the second control chamber 31. The pressure in the second control chamber 31 decreases, the needle valve assembly 6 moves upward, and the injector starts to spray fuel.

[0025] The solenoid valve is closed, the switch valve 2 seals the switch hole 11, oil flows into the second control chamber 31 from the third oil hole 33, the needle valve assembly 6 is pressed downward, and the injector stops spraying oil.

[0026] When the injector begins to flow fuel and the high-pressure fuel fills the first control chamber 12 and the second control chamber 31, because the volume and groove diameter of the first buffer groove 34, the second buffer groove 35, and the third buffer groove 36 are much larger than the diameter of the oil hole in the three-way valve 3, the flow rate of the high-pressure fuel is buffered after entering the third buffer groove 36 from the third oil hole 33, reducing the flow stress of the high-pressure fuel. The high-pressure fuel then undergoes secondary buffering in the first buffer groove 34, so that the high-pressure fuel smoothly enters the first control chamber 12 or the second control chamber 31. This buffering and smooth flow of the high-pressure fuel during the above process are also improved, thereby reducing stress on the first buffer groove 34, the second buffer groove 35, the third buffer groove 36, the inner walls of the first and second control chambers 12 and 31, the switch hole 11, and the third oil hole 33, reducing fatigue damage to the inner wall of the three-way valve 3, and extending the service life of the injector. Similarly, when the injector starts to return oil, the oil flows from the second control chamber 31 through the second slow groove 35 and the first slow groove 34 to the first control chamber 12. When the oil reaches the switch hole 11, the oil pressure has dropped, reducing the generation of cavitation at the switch hole 11.

[0027] See also Figure 2 The three-way valve 3 is also provided with a first oil hole 37 and a second oil hole 32. One end of the first oil hole 37 is connected to the first control chamber 12 through the first slow groove 34, and the other end of the first oil hole 37 is connected to the second control chamber 31 through the second slow groove 35. The second oil hole 32 connects the second control chamber 31 and the injector body 4.

[0028] See also Figure 2 Furthermore, a first buffer groove 34 is provided at the top of the three-way valve 3. The upper end surface of the first buffer groove 34 communicates with the first control chamber 12, and the lower end surface of the first buffer groove 34 is provided with a connecting portion 341 that communicates with the first oil hole 37. One side of the lower end surface of the first buffer groove 34 communicates with the top of the third buffer groove 36. Specifically, the upper end of the first buffer groove 34 is a relatively shallow groove, but the bottom area of the first buffer groove 34 is as large as possible to provide sufficient buffer space. After the switch valve 2 seals the switch hole 11, the second control chamber 31 is quickly filled with high-pressure oil, generating a faster downward pressure, which can more quickly depress the needle valve assembly 6. A connecting portion 341 is provided at the lower middle end of the first buffer groove 34. The connecting portion 341 serves as a connection and buffer, allowing fuel to flow smoothly between the first buffer groove 34 and the second control chamber 31.

[0029] See also Figure 2 Furthermore, the switch hole 11 is provided with a first switch hole section 111 and a second switch hole section 112. The switch valve 2 is used to open or seal the second switch hole section 112. The aperture of the second switch hole section 112 is larger than that of the first switch hole section 111. With this structure, during oil return, the oil flow rate from the first switch hole section 111 is slower than that from the second switch hole section 112, thereby ensuring smooth fuel flow from the first control chamber 12.

[0030] See also Figure 2 Furthermore, the sum of the diameters of the first and third oil holes 37, 33 is smaller than the diameter of the first switch hole section 111, and the diameter of the second oil hole 32 is smaller than the diameter of the first oil hole 37. With this structure, when the injector needs to spray oil, the switch valve 2 opens the switch hole 11, the oil inflow rate into the first control chamber 12 is slower than the oil outflow rate, and the oil in the second control chamber 31 needs to be replenished to the first control chamber 12. Because the diameter of the second oil hole 32 is smaller than that of the first oil hole 37, the oil inflow rate into the second control chamber 31 is slower than the oil outflow rate, reducing the pressure in the second control chamber 31. The needle valve assembly 6 moves upward, and the injector begins spraying oil.

[0031] See also Figure 2 Furthermore, both the first oil hole 37 and the third oil hole 33 are offset from the switch hole 11. Preferably, the third oil hole 33 and the first oil hole 37 are parallel to each other, and the switch hole 11 is located between the third oil hole 33 and the first oil hole 37. This structure prevents high-pressure oil entering the first control chamber 12 from the third oil hole 33 or the first oil hole 37 through the first buffer groove 34 from flowing directly into the switch hole 11, effectively buffering the flow stress of the fuel.

[0032] See also Figure 2 Furthermore, the third oil hole 33 is connected to the injector body 4 through the fourth slow groove 38. With this structure, the fourth slow groove 38 effectively buffers the flow stress of the high-pressure fuel entering the third oil hole 33.

[0033] See also Figure 2 Furthermore, the bottom and top end surfaces of the switch valve 2 are flat, and the metering valve 1 is provided with a sealing surface 13 that cooperates with the switch valve. The switch valve 2 and the sealing surface 13 are in surface contact, with a large contact area, replacing the commonly used switch ball valve and cone sealing end surface. This structure has a stronger sealing ability, and there is no problem of cone surface and steel ball wear. It can ensure long-term stable sealing effect and can adapt to higher fuel pressure.

[0034] By adopting the above-mentioned technical solution, the present invention has the following advantages: When the injector injects fuel or when fuel is supplied to the second control chamber 31 and the first control chamber 12, the first slow groove 34, the second slow groove 35, and the third slow groove 36 in the three-way valve mitigate the flow stress of the high-pressure fuel, thereby not only promoting the smooth flow of high-pressure fuel in the three-way valve 3 but also delaying fatigue damage on the inner wall of the three-way valve 3, thereby increasing the service life of the injector. The three-way valve 3 improves the stable operation of the injector by rationally designing the flow ratio and position of the first oil hole 37, the second oil hole 32, the third oil hole 33, the first switch hole section 111, and the second switch hole section 112.

Claims

1. A common rail injector controlled by a three-way valve, characterized in that: It comprises a fuel injector body (4) and a solenoid valve assembly (5), a switch valve (2), a metering valve (1), a three-way valve (3) and a needle valve assembly (6) arranged in the inner cavity of the fuel injector body (4) from top to bottom; The metering valve (1) is provided with a switch hole (11) on an end surface close to the switch valve (2), and the metering valve (1) is provided with a first control chamber (12) communicated with the switch hole (11); The three-way valve (3) is provided with a third oil hole (33) communicating with the injector body (4); the third oil hole (33) is communicated with the first control chamber (12) through the third slow groove (36) and the first slow groove (34); the third oil hole (33) is communicated with the second control chamber (31) through the third slow groove (36), the first slow groove (34) and the second slow groove (35); the second control chamber (31) is communicated with the first control chamber (12) through the second slow groove (35) and the first slow groove (34); the first slow groove (34), the second slow groove (35) and the third slow groove (36) are used to buffer the flow stress of the fuel.

2. The three-way valve controlled common rail injector according to claim 1, characterized in that: The three-way valve (3) is further provided with a first oil hole (37) and a second oil hole (32). One end of the first oil hole (37) is communicated with the first control chamber (12) through a first slow groove (34), and the other end of the first oil hole (37) is communicated with the second control chamber (31) through a second slow groove (35). The second oil hole (32) connects the second control chamber (31) and the injector body (4).

3. The three-way valve controlled common rail injector according to claim 2, characterized in that: A first slow groove (34) is provided on the top of the three-way valve (3); the upper end surface of the first slow groove (34) is communicated with the first control chamber (12); the lower end surface of the first slow groove (34) is provided with a connecting portion (341) communicated with the first oil hole (37); and one side of the lower end surface of the first slow groove (34) is communicated with the top end of the third slow groove (36).

4. The three-way valve controlled common rail injector according to claim 1, 2 or 3, characterized in that: The switch hole (11) is provided with a first switch hole section (111) and a second switch hole section (112); the switch valve (2) is used to open or seal the second switch hole section (112); the aperture of the second switch hole section (112) is larger than the aperture of the first switch hole section (111).

5. The three-way valve controlled common rail injector according to claim 4, characterized in that: The sum of the apertures of the first oil hole (37) and the third oil hole (33) is smaller than the aperture of the first switch hole section (111), and the aperture of the second oil hole (32) is smaller than the aperture of the first oil hole (37).

6. The three-way valve controlled common rail injector according to claim 2, 3 or 5, characterized in that: The first oil hole (37) and the third oil hole (33) are both arranged in a staggered manner with respect to the switch hole (11).

7. The three-way valve controlled common rail injector according to claim 4, characterized in that: The first oil hole (37) and the third oil hole (33) are both arranged in a staggered manner with respect to the switch hole (11).

8. The three-way valve controlled common rail injector according to claim 1, 2, 3, 5 or 7, characterized in that: The third oil hole (33) is connected to the fuel injector body (4) through the fourth slow groove (38).

9. The three-way valve controlled common rail injector according to claim 1, 2, 3, 5 or 7, characterized in that: The bottom and top end surfaces of the switch valve (2) are flat surfaces, and the metering valve (1) is provided with a sealing surface (13) that matches the switch valve.

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