Fuel injection pump plunger and fuel injection pump

Abstract

The present invention discloses a fuel injection pump plunger and a fuel injection pump, comprising a plunger head, wherein the outer surface of the plunger head is provided with a pressure relief control spiral groove, wherein the pressure relief control spiral groove comprises: an axial pressure relief groove, wherein the axial pressure relief groove extends to the plunger top surface of the plunger head to communicate with the high-pressure oil chamber above the plunger top surface; a first pressure relief spiral groove, which is spirally arranged along the outer surface of the plunger head, and one end of the first pressure relief spiral groove is communicated with the axial pressure relief groove; and a second pressure relief spiral groove, which is spirally arranged along the outer surface of the plunger head, and the second pressure relief spiral groove is located on the upper side of the first pressure relief spiral groove. The stepped double spiral groove structure of the present invention can reduce the deformation of the edge of the pressure relief control spiral groove under high pressure, and prevent the problem of jamming failure caused by excessive deformation of the edge of the pressure relief control spiral groove under high pump end pressure, resulting in excessive local clearance.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel injection pumps, and in particular to a fuel injection pump plunger and a fuel injection pump. Background Art

[0002] With the continuous improvement of the average effective pressure and power of diesel engines, in order to obtain better performance, the pump end pressure of the high-pressure injection pump is forced to increase continuously, resulting in drastic changes and fluctuations in system pressure, and the problems of cavitation and erosion of the injection pump become prominent. Cavitation and erosion lead to the generation of metal particles, which cause the plunger and injector needle valve to get stuck. At the same time, cavitation will also cause holes on the edge of the plunger to damage the seal, resulting in a decrease in pump end pressure. In severe cases, the deformation will be too large, weakening the strength of the plunger, causing the plunger to get stuck due to excessive deformation, causing the diesel engine to be unable to run, and causing problems for the safe use and operation of the diesel engine.

[0003] Therefore, how to solve the plunger cavitation problem, thereby avoiding the reduction of pump end pressure due to the plunger cavitation problem and the problem of the diesel engine being unable to operate due to excessive plunger deformation and jamming, is a technical problem that technical personnel in this field currently need to solve. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide a fuel injection pump plunger to solve the plunger cavitation problem, thereby avoiding the problem of reduced pump end pressure due to plunger cavitation and the problem of the diesel engine being unable to operate due to excessive plunger deformation and jamming.

[0005] Another object of the present invention is to provide a fuel injection pump having the above-mentioned fuel injection pump plunger.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A fuel injection pump plunger includes a plunger head, wherein the outer surface of the plunger head is provided with a pressure relief control spiral groove, and the pressure relief control spiral groove includes:

[0008] an axial pressure relief groove, the axial pressure relief groove extending to the plunger top surface of the plunger head so as to communicate with the high-pressure oil chamber above the plunger top surface;

[0009] a first pressure relief spiral groove, spirally arranged along the outer surface of the plunger head, one end of the first pressure relief spiral groove being connected to the axial pressure relief groove, and a top end of the first pressure relief spiral groove being at a distance T2 from the top surface of the plunger;

[0010] The second pressure relief spiral groove is spirally arranged along the outer surface of the plunger head, and the second pressure relief spiral groove is located on the upper side of the first pressure relief spiral groove to form a stepped groove with the first pressure relief spiral groove. The top end of the second pressure relief spiral groove is at a distance T1 from the top surface of the plunger, and the distance T1 is smaller than the distance T2, and both the distance T1 and the distance T2 are greater than 0.

[0011] Optionally, in the above-mentioned fuel injection pump plunger, when the plunger lift of the fuel injection pump plunger exceeds 15 mm, the lead of the first pressure relief spiral groove is a multiple of 10 mm; and / or,

[0012] The lead of the first pressure relief spiral groove is 3 mm to 5 mm greater than the lead of the second pressure relief spiral groove.

[0013] Optionally, in the above-mentioned fuel injection pump plunger, the distance T1 between the top of the second pressure relief spiral groove and the top surface of the plunger is 5 mm-7 mm; and / or,

[0014] The difference between the distance T1 and the distance T2 is 2 mm to 3 mm.

[0015] Optionally, in the above-mentioned fuel injection pump plunger, the depth T3 of the second pressure relief spiral groove is 0.4 mm-0.6 mm.

[0016] Optionally, in the above-mentioned fuel injection pump plunger, there are two pressure relief control spiral grooves, which are arranged symmetrically along the axis of the plunger head.

[0017] A fuel injection pump comprises a pump body and a plunger pair arranged in the pump body, the plunger pair comprising a plunger sleeve and a fuel injection pump plunger arranged in the plunger sleeve, a high-pressure oil chamber is formed between the plunger top surface of the fuel injection pump plunger and the plunger sleeve, a low-pressure oil chamber is formed between the plunger sleeve and the pump body, the plunger sleeve is provided with an oil inlet and return hole for connecting the low-pressure oil chamber and the high-pressure oil chamber, and the fuel injection pump plunger is the fuel injection pump plunger described in any of the above items.

[0018] Optionally, in the above-mentioned fuel injection pump, a threaded hole is provided at a position of the pump body corresponding to the oil inlet and return hole, the sealing thread at the threaded hole is matched with an oil-blocking bolt, and a concave guide groove is provided on the end face of the oil-blocking bolt facing the oil inlet and return hole.

[0019] Optionally, in the above-mentioned fuel injection pump, the concave guide groove is a concave spherical guide groove, and the axis of the oil inlet and return holes passes through the center of the sphere of the concave guide groove.

[0020] Optionally, in the above-mentioned fuel injection pump, the oil inlet and return holes are tapered holes, and the diameter of the oil inlet and return holes gradually increases in the direction from the fuel injection pump plunger to the oil baffle bolt.

[0021] Optionally, in the above fuel injection pump, the taper of the oil inlet and return holes is 9°-12°; and / or,

[0022] The distance H1 between the oil inlet and return holes and the oil retaining bolt is 4 mm to 6 mm; and / or,

[0023] The depth H2 of the concave guide groove is 2mm-4mm.

[0024] The fuel injection pump plunger provided by the present invention adds a second pressure relief spiral groove on the basis of the traditional pressure relief control spiral groove, and the second pressure relief spiral groove is arranged on the upper part of the first pressure relief spiral groove to form a stepped groove. When the fuel injection pump plunger is supplying oil upward, pressure relief is performed when the pressure relief control spiral groove is connected to the oil inlet and return holes. Since the second pressure relief spiral groove is added to the upper part of the first pressure relief spiral groove, the second pressure relief spiral groove is first connected to the oil inlet and return holes. Since the first pressure relief spiral groove and the second pressure relief spiral groove are stepped grooves, the total depth of the traditional spiral groove is divided into two parts, so that the depth of the first pressure relief spiral groove and the second pressure relief spiral groove are both smaller than the depth of the traditional spiral groove. Since the depth of the second pressure relief spiral groove is smaller, after the pressure relief transition of the second pressure relief spiral groove, the first pressure relief spiral groove is connected to the oil inlet and return holes for complete pressure relief. Because when the injection pump plunger moves upward to supply oil, the pressure relief flow area passes through the transition of the second pressure relief spiral groove, producing a throttling and pressure limiting effect, so no sudden changes will occur. Through the throttling and pressure limiting effect, the pressure change is controlled, thereby preventing the system pressure from changing too suddenly and causing cavitation problems.

[0025] Therefore, the stepped double spiral groove structure of the present invention can reduce the edge deformation of the pressure relief control spiral groove under high pressure, and prevent the problem of jamming failure caused by excessive deformation of the edge of the pressure relief control spiral groove under high pump end pressure, resulting in too small local gap.

[0026] The fuel injection pump provided by the present invention has all the technical effects of the above-mentioned fuel injection pump plunger, and will not be described in detail herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 A cross-sectional view of a fuel injection pump provided by an embodiment of the present invention at one angle;

[0029] Figure 2A cross-sectional view of the fuel injection pump provided by an embodiment of the present invention at another angle;

[0030] Figure 3 A cross-sectional view of the upper half of a fuel injection pump provided in an embodiment of the present invention;

[0031] Figure 4 A schematic structural diagram of a fuel injection pump plunger at one angle provided by an embodiment of the present invention;

[0032] Figure 5 A schematic structural diagram of a fuel injection pump plunger provided by an embodiment of the present invention at another angle;

[0033] Figure 6 A top view of a fuel injection pump plunger provided in an embodiment of the present invention;

[0034] Figure 7 A partial enlarged view of a fuel injection pump plunger at one angle provided by an embodiment of the present invention;

[0035] Figure 8 This is a partial enlarged view of the fuel injection pump plunger at another angle provided by an embodiment of the present invention.

[0036] The meanings of the reference numerals in the figures are as follows:

[0037] 101 is the pump body, 102 is the plunger sleeve, 1021 is the oil inlet and return holes, 103 is the injection pump plunger, 1031 is the plunger top surface, 104 is the oil retaining bolt, 1041 is the concave guide groove, 105 is the high-pressure oil chamber, 106 is, 107 is the pressure relief control spiral groove, 1071 is the axial pressure relief groove, 1072 is the first pressure relief spiral groove, and 1073 is the second pressure relief spiral groove. DETAILED DESCRIPTION

[0038] The core of the present invention is to provide a fuel injection pump plunger to solve the plunger cavitation problem, thereby avoiding the problem of reduced pump end pressure due to plunger cavitation and the problem of the diesel engine being unable to operate due to excessive plunger deformation and jamming.

[0039] Another core of the present invention is to provide a fuel injection pump having the above-mentioned fuel injection pump plunger.

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0041] When the fuel injection pump is operating, the fuel in the high-pressure oil chamber is released through the pressure relief control spiral groove. Often, due to sudden pressure changes, the local pressure on the top surface of the plunger and the edge of the pressure relief control spiral groove drops below 0.9 atmospheres. This causes the fuel to vaporize and form bubbles, which then burst and explode under the positive pressure, generating severe impact forces, sometimes exceeding 1000 MPa, on the plunger surface, causing cavitation damage. Based on this, this embodiment discloses a fuel injection pump plunger 103, the details of which are as follows.

[0042] like Figure 1 as well as Figure 4-Figure 8 As shown, an embodiment of the present invention discloses a fuel injection pump plunger 103, including a plunger head, which is located at one end of the fuel injection pump plunger 103 near the high-pressure oil chamber 105. The outer surface of the plunger head is provided with a pressure relief control spiral groove 107. When the fuel injection pump plunger 103 moves to the point where the pressure relief control spiral groove 107 is connected to the oil inlet and return hole 1021, pressure relief is performed, thereby controlling the effective stroke of the fuel injection pump plunger 103 and the amount of oil distributed. By rotating the fuel injection pump plunger 103 so that different positions of the pressure relief control spiral groove 107 correspond to the oil inlet and return hole 1021, the amount of fuel injection can be adjusted.

[0043] In a specific embodiment of the present invention, the pressure relief control spiral groove 107 includes an axial pressure relief groove 1071 , a first pressure relief spiral groove 1072 and a second pressure relief spiral groove 1073 .

[0044] The axial pressure relief groove 1071 extends to the plunger top surface 1031 of the plunger head to communicate with the high-pressure oil chamber 105 above the plunger top surface 1031, allowing the fuel in the high-pressure oil chamber 105 to flow into the axial pressure relief groove 1071. As in the prior art, the axial pressure relief groove 1071 is located away from the oil inlet and return holes 1021 to prevent direct pressure relief through the axial pressure relief groove 1071.

[0045] The first pressure relief spiral groove 1072 is spirally arranged along the outer surface of the plunger head, and one end of the first pressure relief spiral groove 1072 is connected to the axial pressure relief groove 1071, so that the fuel in the high-pressure oil chamber 105 can flow into the first pressure relief spiral groove 1072 through the axial pressure relief groove 1071.

[0046] There is a distance T2 between the top of the first pressure relief spiral groove 1072 and the plunger top surface 1031. That is, the first pressure relief spiral groove 1072 does not extend to the plunger top surface 1031, but is connected to the high-pressure oil chamber 105 above the plunger top surface 1031 through the axial pressure relief groove 1071. Since the first pressure relief spiral groove 1072 is used to communicate with the oil inlet and return holes 1021 to relieve pressure, it will be impacted by the high-pressure fuel. Therefore, the distance T2 between the top of the first pressure relief spiral groove 1072 and the plunger top surface 1031 can prevent the first pressure relief spiral groove 1072 from extending to the plunger top surface 1031, resulting in excessive deformation of the plunger top and the risk of plunger sticking.

[0047] The second pressure relief spiral groove 1073 is arranged in a spiral along the outer surface of the plunger head, and the second pressure relief spiral groove 1073 is located on the upper side of the first pressure relief spiral groove 1072, so as to form a stepped groove with the first pressure relief spiral groove 1072. The depth of the second pressure relief spiral groove 1073 is smaller than the depth of the first pressure relief spiral groove 1072, and the width of the second pressure relief spiral groove 1073 is smaller than the width of the first pressure relief spiral groove 1072, that is, the flow area of ​​the second pressure relief spiral groove 1073 is significantly smaller than the flow area of ​​the first pressure relief spiral groove 1072.

[0048] The top of the second pressure relief spiral groove 1073 is at a distance T1 from the plunger top surface 1031, that is, the second pressure relief spiral groove 1073 does not extend to the plunger top surface 1031, but is connected to the high-pressure oil chamber 105 above the plunger top surface 1031 through the axial pressure relief groove 1071. Since the second pressure relief spiral groove 1073 is used to connect with the oil inlet and return holes 1021 as a transition before pressure relief, it will be impacted by the high-pressure fuel. Therefore, the top of the second pressure relief spiral groove 1073 is designed to have a distance T1 from the plunger top surface 1031. This can prevent the second pressure relief spiral groove 1073 from extending to the plunger top surface 1031, causing the plunger top to deform excessively and easily causing the plunger to become stuck. Distance T1 is smaller than distance T2, and both distances T1 and T2 are greater than 0.

[0049] The fuel injection pump plunger 103 provided by the present invention adds a second pressure relief spiral groove 1073 on the basis of the traditional pressure relief control spiral groove 107, and the second pressure relief spiral groove 1073 is arranged on the upper part of the first pressure relief spiral groove 1072 to form a stepped groove. When the fuel injection pump plunger 103 is supplying oil upward, pressure relief is performed when the pressure relief control spiral groove 107 is connected to the oil inlet and return hole 1021. Since the second pressure relief spiral groove 1073 is added to the upper part of the first pressure relief spiral groove 1072, the second pressure relief spiral groove 1073 is first connected to the oil inlet and return hole 1021. Since the first pressure relief spiral groove 1072 and the second pressure relief spiral groove 1073 are stepped grooves, the total depth of the traditional spiral groove is divided into two parts, so that the depth of the first pressure relief spiral groove 1072 and the second pressure relief spiral groove 1073 are both smaller than the depth of the traditional spiral groove. Because the depth of the second pressure relief spiral groove 1073 is relatively small, after the pressure relief transition in the second pressure relief spiral groove 1073, the first pressure relief spiral groove 1072 is connected to the oil inlet and return hole 1021 for complete pressure relief. As the injection pump plunger 103 moves upward to supply oil, the pressure relief flow area increases through the transition in the second pressure relief spiral groove 1073, creating a throttling and pressure-limiting effect. Therefore, sudden changes in pressure are prevented. This throttling and pressure-limiting effect controls pressure changes, thereby preventing sudden changes in system pressure that could cause cavitation.

[0050] Therefore, the stepped double spiral groove structure of the present invention can reduce the edge deformation of the pressure relief control spiral groove 107 under high pressure, and prevent the problem of jamming failure caused by excessive deformation of the edge of the pressure relief control spiral groove 107 under high pump end pressure, resulting in too small local gap.

[0051] In a specific embodiment of the present invention, according to the design standard of the fuel injection pump, when the plunger lift of the fuel injection pump plunger exceeds 15 mm, the lead of the first pressure relief spiral groove 1072 should be rounded to a multiple of 10 mm.

[0052] The lead of the first pressure relief spiral groove 1072 is 3mm-5mm larger than the lead of the second pressure relief spiral groove 1073. This results in the distance between the helical lines of the first pressure relief spiral groove 1072 and the second pressure relief spiral groove 1073 gradually decreasing from bottom to top. In other words, when a large single injection volume is required, the distance between the helical lines of the first pressure relief spiral groove 1072 and the second pressure relief spiral groove 1073 is greater, meaning that the width of the second pressure relief spiral groove 1073 is greater, thereby achieving a more effective throttling and pressure-limiting effect and preventing cavitation caused by sudden pressure changes.

[0053] When a small amount of single fuel injection is required or even an emergency stop is required, the distance between the spiral line of the first pressure relief spiral groove 1072 and the spiral line of the second pressure relief spiral groove 1073 is smaller, that is, the width of the second pressure relief spiral groove 1073 is smaller, so as to have a faster pressure relief function to prevent the problem of afterburning, increased fuel consumption and even engine damage due to too slow speed when an emergency stop is required.

[0054] like Figure 4 As shown, further, the distance T1 between the top of the second pressure relief spiral groove 1073 and the plunger top surface 1031 can be designed to be 5mm-7mm, and the difference between distance T1 and distance T2 is 2mm-3mm. Distances T1 and T2 should not be too large, otherwise the plunger inertia and external lubrication will deteriorate. Distances T1 and T2 should not be too small, otherwise the plunger top and the spiral groove will deform significantly, which may easily cause plunger sticking.

[0055] like Figure 8 As shown, further, the depth T3 of the second pressure relief spiral groove 1073 is 0.4mm-0.6mm. Ensuring that the distance between the spiral lines of the first pressure relief spiral groove 1072 and the second pressure relief spiral groove 1073 is moderate, that is, the width of the second pressure relief spiral groove 1073 is moderate, can achieve a good throttling and pressure limiting effect, while preventing excessive throttling and pressure limiting, which would cause the pump end pressure to drop too slowly, resulting in afterburning and increased fuel consumption.

[0056] In one embodiment of the present invention, two pressure relief control spiral grooves 107 are arranged symmetrically along the axis of the plunger head. It should be noted that the pressure relief control spiral grooves 107 should match the position and number of the oil inlet and return holes 1021. Typically, there are two oil inlet and return holes 1021, spaced 180 degrees apart. Therefore, two pressure relief control spiral grooves 107 should also be provided to align with the two oil inlet and return holes 1021.

[0057] like Figure 1-Figure 3 The present invention also discloses a fuel injection pump, comprising a pump body 101 and a plunger assembly disposed within the pump body 101. The plunger assembly comprises a plunger sleeve 102 and a fuel injection pump plunger 103 disposed within the plunger sleeve 102. A high-pressure oil chamber 105 is formed between a plunger top surface 1031 of the fuel injection pump plunger 103 and the plunger sleeve 102. A low-pressure oil chamber 106 is formed between the plunger sleeve 102 and the pump body 101. The plunger sleeve 102 is provided with an oil inlet and return hole 1021 for connecting the low-pressure oil chamber 106 with the high-pressure oil chamber 105. The fuel injection pump plunger 103 is the fuel injection pump plunger disclosed in the above embodiment, and therefore possesses all the technical effects of the above-described fuel injection pump plunger 103, which will not be further described herein.

[0058] To prevent cavitation within the inner cavity of the pump body 101 corresponding to the oil inlet and return holes 1021 of the fuel injection pump, a high-hardness oil retaining bolt 104 is typically installed at the oil inlet and return holes 1021 to improve pressure variations in the oil inlet and return chambers and address the cavitation issue. Specifically, a threaded hole is provided at the pump body 101 corresponding to the oil inlet and return holes 1021, and the oil retaining bolt 104 is threadedly engaged with the sealing thread of the threaded hole.

[0059] However, due to the impact, scouring, and sudden pressure changes of the inlet and return oil, the oil baffle bolt 104 may experience cavitation after a period of use, affecting the reliability of the fuel system. To address this issue, in this embodiment, a concave guide groove 1041 is provided on the end surface of the oil baffle bolt 104 facing the oil inlet and return hole 1021. When the high-pressure oil stream strikes this concave guide groove 1041, it mitigates the turbulence and pressure changes caused by the impact and rebound of the high-pressure oil stream, thereby improving the smooth flow of the fuel and alleviating the cavitation problem.

[0060] Furthermore, the concave guide groove 1041 is a concave spherical guide groove, and the axis of the oil inlet and return hole 1021 passes through the center of the concave guide groove 1041, that is, the position directly opposite the oil inlet and return hole 1021 is the deepest position of the concave guide groove 1041.

[0061] In a specific embodiment of the present invention, the oil inlet and return holes 1021 are tapered holes, and the diameter of the oil inlet and return holes 1021 gradually increases in the direction from the injection pump plunger 103 to the oil baffle bolt 104, thereby reducing the outlet velocity of the oil beam during pressure relief, alleviating the impact of high-pressure oil, and at the same time improving the smooth flow of fuel, slowing down pressure fluctuations, and further improving the cavitation problem.

[0062] The concave guide groove 1041 needs to cover the extension line of the oil inlet and return hole 1021 to prevent it from hitting the end surface and edge of the oil retaining bolt 104 to achieve a better oil retaining effect. The taper of the oil inlet and return hole 1021 can be designed to be 9°-12° to achieve a better guiding effect and prevent excessive changes in flow rate.

[0063] Furthermore, the distance H1 between the oil inlet / return hole 1021 and the oil retaining bolt 104 is 4mm-6mm. This distance should not be too small, as this will affect oil inflow, nor too large, as this will reduce outlet pressure, increase flow velocity, and cause severe turbulence. The depth H2 of the concave guide groove 1041 is 2mm-4mm. This distance should not be too small, as this will increase the impact force of the oil beam, nor too large, as this will cause severe turbulence at the bottom.

[0064] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referenced to each other.

[0065] As used in this application and the claims, unless the context clearly indicates an exception, the terms "a," "an," "an," and / or "the" are not intended to refer to the singular and may include the plural. Generally speaking, the terms "comprise" and "include" only indicate the inclusion of the steps and elements specifically identified, and these steps and elements do not constitute an exclusive list. A method or apparatus may also include other steps or elements. The phrase "comprises a..." does not preclude the presence of additional identical elements in the process, method, product, or apparatus that includes the elements.

[0066] In the following, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the quantity of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features.

[0067] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the core ideas of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from the principles of the present invention, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A fuel injection pump plunger, comprising a plunger head, wherein the outer surface of the plunger head is provided with a pressure relief control spiral groove (107), characterized in that: The pressure relief control spiral groove (107) comprises: An axial pressure relief groove (1071), the axial pressure relief groove (1071) extending to the plunger top surface (1031) of the plunger head to communicate with the high-pressure oil chamber (105) above the plunger top surface (1031); A first pressure relief spiral groove (1072) is spirally arranged along the outer surface of the plunger head, one end of the first pressure relief spiral groove (1072) is connected to the axial pressure relief groove (1071), and a top end of the first pressure relief spiral groove (1072) is at a distance T2 from the plunger top surface (1031); A second pressure relief spiral groove (1073) is spirally arranged along the outer surface of the plunger head, and the second pressure relief spiral groove (1073) is located on the upper side of the first pressure relief spiral groove (1072) to form a stepped groove with the first pressure relief spiral groove (1072), and a top end of the second pressure relief spiral groove (1073) is at a distance T1 from the plunger top surface (1031), the distance T1 is smaller than the distance T2, and both the distance T1 and the distance T2 are greater than 0; When the plunger lift of the fuel injection pump plunger exceeds 15 mm, the lead of the first pressure relief spiral groove (1072) is a multiple of 10 mm.

2. The fuel injection pump plunger according to claim 1, characterized in that: The lead of the first pressure relief spiral groove (1072) is 3 mm to 5 mm greater than the lead of the second pressure relief spiral groove (1073).

3. The fuel injection pump plunger according to claim 1, characterized in that: The distance T1 between the top of the second pressure relief spiral groove (1073) and the top surface (1031) of the plunger is 5 mm to 7 mm; and / or, The difference between the distance T1 and the distance T2 is 2 mm to 3 mm.

4. The fuel injection pump plunger according to claim 1, characterized in that: The depth T3 of the second pressure relief spiral groove (1073) is 0.4 mm-0.6 mm.

5. The fuel injection pump plunger according to any one of claims 1 to 4, characterized in that: There are two pressure relief control spiral grooves (107), which are arranged symmetrically along the axis of the plunger head.

6. A fuel injection pump, comprising a pump body (101) and a plunger pair arranged in the pump body (101), the plunger pair comprising a plunger sleeve (102) and a fuel injection pump plunger (103) arranged in the plunger sleeve (102), a high-pressure oil chamber (105) is formed between the plunger top surface (1031) of the fuel injection pump plunger (103) and the plunger sleeve (102), a low-pressure oil chamber (106) is formed between the plunger sleeve (102) and the pump body (101), the plunger sleeve (102) is provided with an oil inlet and return hole (1021) for connecting the low-pressure oil chamber (106) and the high-pressure oil chamber (105), characterized in that: The fuel injection pump plunger (103) is the fuel injection pump plunger according to any one of claims 1 to 5.

7. The fuel injection pump according to claim 6, characterized in that A threaded hole is provided at a position of the pump body (101) corresponding to the oil inlet and return hole (1021); an oil retaining bolt (104) is provided in sealing engagement with the threaded hole; and a concave guide groove (1041) is provided on the end surface of the oil retaining bolt (104) facing the oil inlet and return hole (1021).

8. The fuel injection pump according to claim 7, characterized in that: The concave guide groove (1041) is a concave spherical guide groove, and the axis of the oil inlet and return hole (1021) passes through the center of the sphere of the concave guide groove (1041).

9. The fuel injection pump according to claim 8, characterized in that: The oil inlet and return holes (1021) are tapered holes, and the diameter of the oil inlet and return holes (1021) gradually increases in the direction from the fuel injection pump plunger (103) to the oil retaining bolt (104).

10. The fuel injection pump according to claim 9, characterized in that: The taper of the oil inlet and return holes (1021) is 9°-12°; and / or, The distance H1 between the oil inlet and return hole (1021) and the oil retaining bolt (104) is 4 mm to 6 mm; and / or, The depth H2 of the concave guide groove (1041) is 2 mm to 4 mm.

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