A plunger pair for a high-pressure common rail system

Abstract

This patent relates to the technical field of internal combustion engine plunger pairs, specifically a plunger pair for a high-pressure common rail system, comprising a plunger, a plunger sleeve, an oil inlet valve, an oil inlet valve seat, and an oil inlet valve spring. The plunger is mounted on the lower portion of the plunger sleeve, a countersunk hole is provided on the top of the plunger sleeve, the oil inlet valve seat is mounted in the countersunk hole on the top of the plunger sleeve, the oil inlet valve is slidably connected to the oil inlet valve seat, the oil inlet valve spring sleeve is mounted on the outside of the oil inlet valve, a through hole is provided in the middle of the oil inlet valve, an annular connecting groove is provided on the top of the oil inlet valve, a plurality of leakage return oil channels are provided in the plunger sleeve, two annular grooves are provided on the inner side of the lower portion of the plunger sleeve, the annular groove on the upper portion is connected to the plurality of leakage return oil channels, and a sealing ring is installed in the annular groove on the lower portion. In this solution, when the plunger sleeve is deformed by force, the gap can offset the deformation, so that the deformation of the plunger sleeve will not affect the oil inlet valve seat or the sealing surface, thereby solving the problem of micro-wear caused by deformation between the plunger sleeve and the high-pressure sealing surface of the oil outlet valve seat.

Description

Technical Field

[0001] The invention relates to the technical field of internal combustion engine plunger pairs, in particular to a plunger pair for a high-pressure common rail system. Background Art

[0002] The operating environment of a high-pressure common rail system is complex. The high operating pressure and frequency of operation place heavy loads on the plunger pressure chamber and related components. This high operating frequency also subjects these components to high-frequency alternating loads. Conventional plunger components experience abnormal wear during use due to these alternating loads, known as fretting wear. Experimental analysis has shown that fretting wear primarily occurs on the high-pressure sealing surface between the plunger sleeve and the oil outlet valve seat, particularly near the plunger pressure chamber.

[0003] After experimental analysis, it was found that the generation of non-dynamic wear mainly includes two factors: First, the conventional structure of the plunger pair, at the high-pressure sealing surface close to the plunger pressure chamber, the inner cavity is in the high-pressure zone, and the force-bearing area there is large. When the force inside the plunger pressure chamber generates a pulsed high pressure, it will cause the plunger sleeve to produce a large deformation at the high-pressure sealing surface. This deformation causes a slight relative movement between the plunger sleeve and the oil outlet valve seat. On the other hand, when the plunger sleeve and the oil outlet valve seat are fixed and pressed against each other, due to the use of bolts for connection, the bolts will cause the plunger sleeve to produce a slight deformation during the force process. In summary, between the plunger sleeve of the conventional structure and the high-pressure sealing surface of the oil outlet valve seat, the deformation caused by the above two situations will cause micro-motion wear, which greatly reduces the reliability and life of the product. Summary of the Invention

[0004] The present invention aims to provide a plunger pair for a high-pressure common rail system to solve the problem of fretting wear caused by deformation between the plunger sleeve and the high-pressure sealing surface of the oil outlet valve seat.

[0005] In order to achieve the above-mentioned purpose, the basic scheme of the present invention is as follows: A plunger pair for a high-pressure common rail system, comprising a plunger, a plunger sleeve, an oil inlet valve, an oil inlet valve seat and an oil inlet valve spring, the plunger being installed at the lower part of the plunger sleeve, a countersunk hole being provided at the top of the plunger sleeve, the oil inlet valve seat being installed in the countersunk hole at the top of the plunger sleeve, the oil inlet valve being slidably connected in the oil inlet valve seat, the oil inlet valve spring sleeve being arranged on the outside of the oil inlet valve, a through hole being provided in the middle of the oil inlet valve, an annular connecting groove being provided at the top of the oil inlet valve, a plurality of leakage return oil channels being provided in the plunger sleeve, two annular grooves being provided on the inner side of the lower part of the plunger sleeve, the annular groove located at the upper part being connected to the plurality of leakage return oil channels, and a sealing ring being installed in the annular groove located at the lower part.

[0006] Furthermore, it also includes an oil outlet valve assembly, which includes an oil outlet valve, an oil outlet valve seat and an oil outlet valve spring, wherein the oil outlet valve seat is installed on the top of the plunger sleeve, the upper part of the oil outlet valve seat is provided with a countersunk hole, the oil outlet valve is installed on the upper part of the oil outlet valve seat, the upper part of the oil outlet valve is provided with a countersunk hole, the oil outlet valve spring is installed in the countersunk hole on the upper part of the oil outlet valve, the bottom of the oil outlet valve seat is provided with an oil outlet port, the oil outlet port is connected with the through hole in the middle of the oil inlet valve, the oil outlet valve seat is provided with a plurality of transversely arranged low-pressure oil inlet holes and a plurality of downwardly inclined oil inlet channels, several of the low-pressure oil inlet holes are respectively connected with a plurality of oil inlet channels, and several of the oil inlet channels are all connected with the annular connecting groove on the top of the oil inlet valve, and the oil outlet valve seats above several of the leakage return oil channels are provided with connecting holes, and the connecting holes connect the low-pressure oil inlet holes and the leakage return oil channel.

[0007] Furthermore, the outer circle of the oil inlet valve seat is set to a two-stage outer circle, and the upper part of the plunger sleeve is provided with a two-stage countersunk hole. The two-stage outer circles of the oil inlet valve seat are respectively matched with the two-stage countersunk holes of the plunger sleeve. The outer circle of the lower part of the oil inlet valve seat and the plunger sleeve adopt a transition fit at the fit, and the outer circle of the upper part of the oil inlet valve seat and the plunger sleeve adopt a clearance fit, and the clearance is 5μ~20μ.

[0008] Furthermore, the oil inlet valve is provided with a two-stage outer circle, and the upper part of the oil inlet valve seat is provided with a two-stage countersunk hole. The height of the countersunk hole on the upper part of the oil inlet valve seat is greater than the height of the outer circle of the upper part of the oil inlet valve, and the clearance between the upper outer circle of the oil inlet valve and the upper countersunk hole of the oil inlet valve seat is matched, and the clearance is 0.2mm~0.5mm. The oil inlet valve spring is located in the countersunk hole at the lower part of the oil inlet valve seat, and the clearance between the lower outer circle of the oil inlet valve and the center hole of the oil inlet valve seat is matched, and the clearance is 3μ~10μ.

[0009] Furthermore, the edge of the oil outlet valve seat is provided with a plurality of bolt through holes, the top surface of the plunger sleeve is provided with a plurality of threaded holes corresponding to the bolt through holes, and the oil outlet valve seat is detachably connected to the plunger sleeve by bolts.

[0010] Furthermore, a countersunk hole is provided on the upper portion of the threaded hole.

[0011] Furthermore, the diameter of the through hole in the middle of the oil inlet valve is consistent with the diameter of the oil outlet of the oil outlet valve seat.

[0012] The beneficial effects of this solution are as follows: (1) In this solution, a two-stage countersunk hole is provided on the upper part of the plunger sleeve, and an oil inlet valve seat is installed in the countersunk hole, and two high-pressure sealing surfaces are formed through the upper and lower end faces of the oil inlet valve seat respectively; the outer circle of the lower part of the oil inlet valve seat and the plunger sleeve countersunk hole are transitionally matched to ensure that the oil inlet valve seat is positioned radially and is positioned axially through the end face of the plunger sleeve countersunk hole; the outer circle of the upper part of the oil inlet valve seat and the middle hole of the plunger sleeve are clearance matched, and the clearance is set to 5μ~20μ. When the plunger sleeve is deformed by force, the clearance can offset the deformation, so that the deformation of the plunger sleeve will not affect the oil inlet valve seat or the sealing surface.

[0013] (2) The inlet valve and the inlet valve seat are matched to form an inlet valve pair, and the second-stage outer circle of the inlet valve and the center hole of the inlet valve seat adopt a clearance fit, and the clearance is set to 3μ~10μ. On the one hand, it can ensure that the outlet valve is guided when opening and closing. On the other hand, the dynamic seal formed by the clearance fit here can completely separate the high-pressure fuel from the high-pressure sealing surface of the inlet valve seat and the inlet valve spring, ensuring that the high-pressure sealing surface of the inlet valve seat will not be deformed by the alternating high-pressure load. The first-stage outer circle of the inlet valve and the center hole of the inlet valve seat adopt a clearance fit, and the clearance is set to 0.2mm~0.5mm. When the inlet valve is deformed by high pressure, the clearance here will offset the deformation of the inlet valve, ensuring that the inlet valve seat will not be affected and the high-pressure sealing surface will not be affected.

[0014] (3) A through hole is set in the middle of the oil inlet valve, and the diameter of the through hole is consistent with the diameter of the oil outlet of the oil outlet valve seat, ensuring that there will be no pressure loss when the plunger is supplying oil upward, thereby improving the oil supply efficiency of the plunger pair.

[0015] (4) The oil inlet valve spring is installed between the countersunk step at the bottom of the oil inlet valve seat and the oil inlet valve. The working environment is not affected by high pressure, which improves the working reliability and service life of the spring.

[0016] (5) By setting the threaded hole countersink, the force point of the bolt can be changed, reducing the influence of the bolt on the large end face of the plunger sleeve. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the overall structure of an embodiment of the present invention;

[0018] Figure 2 for Figure 1 A is an enlarged schematic diagram;

[0019] Figure 3 A schematic diagram of a threaded hole structure according to an embodiment of the present invention;

[0020] Figure 4 Schematic diagram of the oil hole structure of the oil outlet valve seat according to an embodiment of the present invention. DETAILED DESCRIPTION

[0021] 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.

[0022] The figure marks in the drawings of the specification include: plunger 1, plunger sleeve 2, oil inlet valve 3, oil inlet valve seat 4, oil inlet valve spring 5, oil outlet valve 6, oil outlet valve seat 7, oil outlet valve spring 8, annular connecting groove 9, leakage return oil channel 10, annular groove 11, bolt through hole 12, threaded hole 13, oil outlet 14, low-pressure oil inlet hole 15, oil inlet channel 16, connecting hole 17. Example

[0023] Basically as attached Figure 1 As shown: A plunger couple for a high-pressure common rail system, comprising a plunger 1, a plunger sleeve 2, an oil inlet valve 3, an oil inlet valve seat 4, an oil inlet valve spring 5, an oil outlet valve 6, an oil outlet valve seat 7 and an oil outlet valve spring 8. The plunger 1 is mounted on the lower part of the plunger sleeve 2 and is combined with the plunger sleeve 2. Figure 2 As shown, the outer circle of the oil inlet valve seat 4 is set to a two-stage outer circle, and the upper part of the plunger sleeve 2 is provided with a two-stage countersunk hole. The two-stage outer circles of the oil inlet valve seat 4 are respectively matched with the two-stage countersunk holes of the plunger sleeve 2. The outer circle of the lower part of the oil inlet valve seat 4 and the plunger sleeve 2 adopt a transition fit, and the outer circle of the upper part of the oil inlet valve seat 4 and the plunger sleeve 2 adopt a clearance fit, and the clearance is 5μ~20μ; the oil inlet valve 3 is slidably connected in the oil inlet valve seat 4, the oil inlet valve spring 5 is set on the outside of the oil inlet valve 3, the middle part of the oil inlet valve 3 is provided with a through hole, the oil inlet valve 3 is provided with a two-stage outer circle, the upper part of the oil inlet valve seat 4 is provided with a two-stage countersunk hole, and the countersunk hole on the upper part of the oil inlet valve seat 4 The height is greater than the height of the upper outer circle of the oil inlet valve 3, and the upper outer circle of the oil inlet valve 3 and the upper countersunk hole of the oil inlet valve seat 4 are matched, the gap is 0.2mm~0.5mm, the oil inlet valve spring 5 is located in the countersunk hole at the bottom of the oil inlet valve seat 4, and the lower outer circle of the oil inlet valve 3 and the central hole of the oil inlet valve seat 4 are matched, the gap is 3μ~10μ; an annular connecting groove 9 is provided on the top of the oil inlet valve 3, two leakage return oil channels 10 are provided in the plunger sleeve 2, and two annular grooves 11 are provided on the inner side of the lower part of the plunger sleeve 2. The annular groove 11 located at the upper part is connected to the two leakage return oil channels 10, and a sealing ring is installed in the annular groove 11 located at the lower part.

[0024] Combine Figure 3 As shown, the oil outlet valve seat 7 is installed on the top of the plunger sleeve 2, and four bolt through holes 12 are provided on the edge of the oil outlet valve seat 7. The top surface of the plunger sleeve 2 is provided with four threaded holes 13 corresponding to the bolt through holes 12. The upper part of the threaded hole 13 is provided with a countersunk hole, and the oil outlet valve seat 7 is detachably connected to the plunger sleeve 2 by bolts; the upper part of the oil outlet valve seat 7 is provided with a countersunk hole, the oil outlet valve 6 is installed on the upper part of the oil outlet valve seat 7, the upper part of the oil outlet valve 6 is provided with a countersunk hole, the oil outlet valve spring 8 is installed in the countersunk hole on the upper part of the oil outlet valve 6, and the bottom of the oil outlet valve seat 7 is provided with an oil outlet port 14 with the same aperture as the through hole in the middle of the oil inlet valve 3. The oil outlet port 14 is connected to the through hole in the middle of the oil inlet valve 3, combined with Figure 4As shown, eight transversely arranged low-pressure oil inlet holes 15 and eight downwardly inclined oil inlet channels 16 are provided on the oil outlet valve seat 7. The eight low-pressure oil inlet holes 15 are respectively connected to the eight oil inlet channels 16. The eight oil inlet channels 16 are all connected to the annular connecting groove 9 at the top of the oil inlet valve 3. A connecting hole 17 is provided on the oil outlet valve seat 7 above the two leakage oil return channels 10. The connecting hole 17 connects the low-pressure oil inlet holes 15 and the leakage oil return channels 10.

[0025] The specific implementation process is as follows: during operation, the low-pressure fuel acts on the annular connecting groove 9 on the end face of the oil inlet valve 3 through the low-pressure oil inlet hole 15 and the oil inlet channel 16. When the plunger 1 moves downward, the pressure in the pressure chamber of the plunger 1 decreases. At this time, the oil inlet valve 3 overcomes the preload force of the oil inlet valve spring 5 and moves downward under the hydraulic force of the fuel, opening the oil inlet valve 3, and the low-pressure fuel flows into the pressure chamber of the plunger 1 through the oil outlet 14; when the plunger 1 moves upward, the pressure in the pressure chamber of the plunger 1 increases. At this time, the oil inlet valve 3 overcomes the liquid pressure of the large end face and moves upward under the action of the upward liquid pressure in the pressure chamber of the plunger 1 and the spring restoring force, closing the oil inlet valve 3; and as the plunger 1 continues to rise, the pressure in the pressure chamber of the plunger 1 continues to rise, and the oil outlet valve 6 is opened to realize the oil supply process. After the oil supply is completed, the plunger 1 moves downward, and the above process is repeated, wherein the fuel leaked from the gap of the plunger 1 flows into the low-pressure oil inlet hole 15 through the leakage return hole. During this process, high-pressure fuel mainly flows from the pressure chamber of the plunger 1 into the oil outlet 14 and flows out through the oil outlet valve 6. It will not directly act on the oil inlet valve spring 5 and the high-pressure sealing surface position, ensuring that during operation, the high-pressure sealing surface of the oil inlet valve seat 4 will not be deformed or fretting. This greatly improves the working environment of the high-pressure sealing surface and enhances the service life and reliability of the product.

[0026] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0027] The above is only an embodiment of the present invention. Common knowledge such as the known specific structures and characteristics in the scheme is not described in detail here. Ordinary technicians in the field are aware of all common technical knowledge in the technical field of the invention before the application date or priority date, can obtain all existing technologies in the field, and have the ability to apply conventional experimental means before that date. Ordinary technicians in the field can improve and implement this scheme in combination with their own abilities under the inspiration given by this application. Some typical known structures or known methods should not become obstacles for ordinary technicians in the field to implement this application. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention. These will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A plunger assembly for a high-pressure common rail system, characterized by: The cam is provided with a through hole on the top of the oil inlet valve seat, and the oil inlet valve seat is installed in the through hole on the top of the oil inlet valve seat. The outer circle of the oil inlet valve seat is set as a two-stage outer circle, and the upper part of the oil inlet valve seat is provided with a two-stage countersunk hole. The two-stage outer circles of the oil inlet valve seat are respectively matched with the two-stage countersunk holes of the oil inlet valve seat. The outer circle of the upper part of the oil inlet valve seat and the plunger sleeve adopt a clearance fit. The oil inlet valve is slidably connected to the oil inlet valve seat, and the oil inlet valve spring is set on the outside of the oil inlet valve. A through hole is provided in the middle of the oil inlet valve and an annular connecting groove is provided on the top of the oil inlet valve. The plunger sleeve is provided with several leakage return oil channels, and the inner side of the lower part of the plunger sleeve is provided with two annular grooves, the annular groove located on the upper part is connected with several leakage return oil channels, and a sealing ring is installed in the annular groove located on the lower part. The oil outlet valve assembly includes an oil outlet valve seat, and the oil outlet valve seat is installed on the top of the plunger sleeve. The oil outlet valve seat is provided with several transversely arranged low-pressure oil inlet holes and several downwardly inclined oil inlet channels, several of the low-pressure oil inlet holes are respectively connected with several oil inlet channels, and several of the oil inlet channels are all connected with the annular connecting groove on the top of the oil inlet valve. When the oil inlet valve is in the closed state, the top surface of the oil inlet valve is flush with the top surface of the oil inlet valve seat and is against the bottom surface of the oil outlet valve seat.

2. The plunger assembly for a high-pressure common rail system according to claim 1, characterized in that: The oil outlet valve assembly also includes an oil outlet valve and an oil outlet valve spring. A countersunk hole is provided on the upper part of the oil outlet valve seat. The oil outlet valve is installed on the upper part of the oil outlet valve seat. A countersunk hole is provided on the upper part of the oil outlet valve. The oil outlet valve spring is installed in the countersunk hole on the upper part of the oil outlet valve. An oil outlet port is provided at the bottom of the oil outlet valve seat. The oil outlet port is connected with the through hole in the middle of the oil inlet valve. A connecting hole is provided on the oil outlet valve seat above several of the leakage return oil channels. The connecting hole connects the low-pressure oil inlet port and the leakage return oil channel.

3. The plunger assembly for a high-pressure common rail system according to claim 1, characterized in that: The outer circle of the lower part of the oil inlet valve seat and the plunger sleeve are matched at a transition fit, and the clearance between the outer circle of the upper part of the oil inlet valve seat and the plunger sleeve is 5μ to 20μ.

4. The plunger assembly for a high-pressure common rail system according to any one of claim 3, characterized in that: The oil inlet valve is provided with a two-stage outer circle, and the upper part of the oil inlet valve seat is provided with a two-stage countersunk hole. The height of the countersunk hole on the upper part of the oil inlet valve seat is greater than the height of the outer circle of the upper part of the oil inlet valve, and the outer circle of the upper part of the oil inlet valve and the countersunk hole on the upper part of the oil inlet valve seat are matched with each other, and the gap is 0.2mm~0.5mm. The oil inlet valve spring is located in the countersunk hole at the lower part of the oil inlet valve seat, and the outer circle of the lower part of the oil inlet valve and the center hole of the oil inlet valve seat are matched with each other, and the gap is 3μ~10μ.

5. The plunger assembly for a high-pressure common rail system according to claim 2, characterized in that: The edge of the oil outlet valve seat is provided with a plurality of bolt through holes, the top surface of the plunger sleeve is provided with a plurality of threaded holes corresponding to the bolt through holes, and the oil outlet valve seat is detachably connected to the plunger sleeve by bolts.

6. The plunger assembly for a high-pressure common rail system according to claim 5, characterized in that: A countersunk hole is provided on the upper portion of the threaded hole.

7. The plunger assembly for a high-pressure common rail system according to claim 6, characterized in that: The diameter of the through hole in the middle of the oil inlet valve is consistent with the aperture of the oil outlet of the oil outlet valve seat.

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