Tappet-free cylinder type oil supply pump and oil injection system

Abstract

The utility model discloses a tappet-free body type oil feed pump and an oil injection system, and relates to the technical field of oil injection systems, the tappet-free body type oil feed pump comprises a body with an oil cavity, the oil cavity at least comprises a first cavity body used for installing an eccentric cam assembly and a second cavity body used for installing an oil pumping assembly, the first cavity body is communicated with the second cavity body, and the first cavity body is communicated with the second cavity body. The oil pumping assembly comprises a plug sleeve installed in the body and a plunger movably connected in the plug sleeve, the plunger and the plug sleeve are elastically connected through an elastic piece, and the eccentric cam assembly makes contact with the plunger so as to jack up the plunger. Two large-mass parts, namely a tappet body and a spring lower seat, are omitted, so that the motion inertia caused by the unsprung mass of the plunger spring is effectively reduced, and the high-rotating-speed operation of the oil supply pump is favorably realized.

Description

Technical Field

[0001] The utility model relates to the technical field of fuel injection systems, in particular to a tappetless fuel supply pump and a fuel injection system. Background Technique

[0002] With the increasingly high requirements of fuel vehicle emission regulations and the increasing demand for engine power from customers, diesel engines generally adopt the technical route of high-pressure common rail fuel injection systems. In order to inject more fuel in a short time, improve the combustion condition, and further improve the emission of the engine, a more effective means is to improve the injection pressure and optimize the injection rate during fuel injection to improve the atomization effect of the fuel, so that the fuel can burn more fully, which requires the fuel system to provide sufficiently stable high-pressure fuel. The high-pressure common rail fuel supply pump is one of the core components of the fuel system, and its working performance stability and reliability are of great significance to the fuel system. Especially in recent years, the engine matching requirements for the common rail system are to provide higher and higher rail pressures and sufficient fuel supply; to meet the requirements, the rotational speed design of the high-pressure fuel supply pump is getting higher and higher, which puts forward more stringent requirements for the working stability of the high-pressure fuel supply pump and the reliability of its components.

[0003] As Figure 7 shown, most of the existing in-line high-pressure fuel supply pumps are equipped with an independent component of a tappet body 10. The tappet body 10 is a component that transmits thrust between the camshaft 5 and the plunger 8. Under the pre-tightening force of the plunger spring, the spring lower seat 11 ensures that the bottom of the plunger is in close contact with the upper plane of the tappet body 10. The roller 20 at the lower end of the tappet body 10 is in close contact with the cam surface of the camshaft 5. The rotational movement of the camshaft 5 drives the tappet body 10 to reciprocate up and down. The tappet body 10 transmits the vertical component force in the acting force applied by the camshaft 5 to the plunger 8 to enable the plunger 8 to reciprocate up and down, and the plunger 8 component realizes the fuel pumping function.

[0004] Using the tappet body 10 as an intermediate force transmission component makes the force application point at the bottom of the plunger 8 theoretically coincide with the axis of the plunger 8. The plunger 8 only bears the component force in the vertical direction perpendicular to the axis of the camshaft 5 during the rotational movement of the camshaft 5 and is not affected by external lateral forces; in this way, the risk of failure of contact friction between the reciprocating movement of the plunger 8 and the bush 7 can be reduced. However, since the tappet body 10 and the spring lower seat 11 account for a large proportion of the components of the mass below the plunger spring, with the increasing demand for the rotational speed of the fuel supply pump in development, the tappet body 10 instead brings limitations to the increase of the rotational speed of the fuel supply pump. After the rotational speed of the fuel supply pump increases, the fatigue life of the plunger spring will decrease after high-frequency compression. The mass of the tappet body 10 and the spring lower seat 11 makes the moment of inertia of the movement of the mass below the plunger spring larger, and at high rotational speeds, the risk of the tappet body 10 disengaging from the surface of the camshaft 5 is higher. Once the tappet body 10 disengages, the balance of thrust transmission of the fuel supply pump is broken, which will cause situations such as jamming of the plunger 8 and the tappet body 10 being broken by the cam, and the function of the fuel supply pump will be lost. Summary of the Utility Model

[0005] Aiming at the deficiencies existing in the prior art, the first object of the present utility model is to provide a tappetless fuel supply pump, which eliminates two components with relatively large masses, namely the tappet body and the spring lower seat, effectively reducing the inertia caused by the mass under the plunger spring and facilitating the high-speed operation of the fuel supply pump.

[0006] To achieve the above object, the present utility model adopts the following technical solutions:

[0007] A tappetless fuel supply pump includes: a body having an oil chamber, the oil chamber at least including a first chamber for installing an eccentric cam assembly and a second chamber for installing a fuel pumping assembly, the first chamber and the second chamber being in communication with each other, the fuel pumping assembly including a sleeve installed in the body and a plunger movably connected in the sleeve, the plunger and the sleeve being elastically connected by an elastic member, and the eccentric cam assembly contacting the plunger to lift the plunger.

[0008] Compared with the prior art, the present utility model has the following beneficial effects:

[0009] By eliminating two components with relatively large masses, namely the tappet body and the spring lower seat, the inertia caused by the mass under the plunger spring is effectively reduced. The elastic member only needs to ensure stable contact between the plunger and the surface of the eccentric cam assembly, greatly reducing the restoring force required by the plunger, improving the return response speed of the plunger, and significantly reducing the risk of the plunger disengaging, which is beneficial to the high-speed operation of the fuel supply pump.

[0010] As a preferred solution, a groove is provided on the inner wall of the sleeve, and an oil inlet passage and an oil return passage communicating with the groove are further provided on the sleeve, and the other ends of the oil inlet passage and the oil return passage are in communication with the second chamber.

[0011] As a preferred solution, the groove is annular, and the oil inlet passage and the oil return passage are circumferentially arranged at intervals around the axis of the groove.

[0012] As a preferred solution, the oil inlet passage and / or the oil return passage are evenly distributed.

[0013] As a preferred solution, the body includes a pump cover assembly and a pump body, and also includes an inlet valve and an outlet valve, and the inlet valve and the outlet valve are installed on the pump cover assembly in a "V" shape.

[0014] As a preferred solution, the eccentric cam assembly includes a camshaft, one end of the camshaft is connected to an oil transfer pump through a connecting block, a first oil passage is provided between the camshaft and an adjacent mating part, and the pump body is provided with a second oil passage communicating with the first oil passage.

[0015] The second object of the present utility model is to provide an injection system, which effectively reduces the inertia brought by the mass under the plunger spring and is beneficial to the high-speed operation of the fuel supply pump.

[0016] To achieve the above object, the present utility model adopts the following technical solutions:

[0017] An injection system includes the tappetless fuel supply pump described in any one of the above.

[0018] Compared with the prior art, the present utility model has the following beneficial effects:

[0019] By canceling the tappet body and the spring lower seat, which are two components with relatively large masses, the inertia brought by the mass under the plunger spring is effectively reduced. The elastic member only needs to ensure stable contact between the plunger and the surface of the eccentric cam assembly, greatly reducing the restoring force required by the plunger, improving the plunger return response speed, and significantly reducing the risk of the plunger disengaging, which is beneficial to the high-speed operation of the fuel supply pump; thus improving the operation of the injection system. Description of the Drawings

[0020] Figure 1 It is a cross-sectional view of the fuel supply pump in some of the embodiments;

[0021] Figure 2 It is a schematic structural diagram of the plunger without an eccentric distance;

[0022] Figure 3 It is a schematic structural diagram of the plunger with an eccentric distance;

[0023] Figure 4 It is a schematic structural diagram of the cooperation between the plunger and the plug sleeve;

[0024] Figure 5 It is a schematic structural diagram of the layout of the oil inlet passage and the oil return passage;

[0025] Figure 6 It is a schematic structural diagram of the forced cooling circulation oil path of the connecting block;

[0026] Figure 7 It is a cross-sectional view of the fuel supply pump in the prior art.

[0027] In the above drawings:

[0028] 1. Pump body; 2. Pump cover; 3. First cavity; 4. Second cavity; 5. Camshaft; 6. Slide sleeve assembly; 7. Plug sleeve; 8. Plunger; 9. Elastic member; 10. Tappet body; 11. Spring lower seat; 12. Groove; 13. Oil inlet passage; 14. Oil return passage; 15. Inlet valve; 16. Outlet valve; 17. Connecting block; 18. First oil passage; 19. Second oil passage; 20. Roller. Detailed Embodiments

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part rather than all of the embodiments of the present invention; the structures described in various embodiments can be freely combined without conflict in terms of structure or principle.

[0030] In the present invention, unless otherwise clearly defined and limited, the terms "installation", "connection", "connection", "fixation" and other terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship when the product of the present invention is normally placed. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first", "second", etc. are only used for descriptive distinction and cannot be understood as indicating or implying relative importance.

[0032] The following will describe some embodiments of the present invention with reference to the accompanying drawings:

[0033] The present invention provides a tappetless fuel supply pump, as Figure 1As shown in the figure, it includes: a body with an oil chamber, the body includes a pump body 1 and a cover assembly detachably connected to the pump body 1 by fasteners such as bolts. The cover assembly is composed of a pump cover 2, an inlet metering unit, an inlet valve 15, an outlet valve 16, an overflow valve assembly, a pressure limiting valve assembly, etc. The structures of their respective components are prior arts and will not be elaborated here. The oil chamber at least includes a first chamber 3 for installing an eccentric cam assembly and a second chamber 4 for installing an oil pumping assembly. The eccentric cam assembly includes a camshaft 5 with an eccentric cam. Preferably, each cam is correspondingly assembled with a sliding sleeve assembly 6 with self-lubricating characteristics (the structure of the sliding sleeve assembly 6 itself is a prior art). To meet the high-speed requirements of the high-pressure fuel pump, an eccentric single cam is selected. The axes of the first chamber 3 and the second chamber 4 are perpendicular to each other; the first chamber 3 and the second chamber 4 are connected and communicate with each other. The oil pumping assembly includes a plug sleeve 7 installed in the body and a plunger 8 movably connected in the plug sleeve 7. Exemplarily, the pump cover 2 is provided with an internal thread, the plug sleeve 7 is provided with an external thread and is screwed tightly on the pump cover 2; the plunger 8 and the plug sleeve 7 are elastically connected by an elastic member 9 such as a spring, and the outer wall of the sliding sleeve assembly 6 of the eccentric cam assembly contacts the bottom end of the plunger 8.

[0034] Under the pre-tightening force of the elastic member 9, the plunger 8 is in stable contact with the surface of the sliding sleeve assembly 6. The eccentric cam on the camshaft 5 drives the sliding sleeve assembly 6 to roll. While rolling friction occurs between the sliding sleeve assembly 6 and the pressure-bearing disc at the bottom of the plunger 8, thrust is transmitted, converting the rotational motion of the camshaft 5 into the reciprocating linear motion of the plunger 8 to achieve the oil pumping function.

[0035] By eliminating several components with relatively large masses such as the tappet body 10, its roller 20, and the spring lower seat 11, the inertia brought by the mass under the plunger spring is effectively reduced. The elastic member 9 only needs to ensure stable contact between the plunger 8 and the surface of the eccentric cam assembly, greatly reducing the restoring force required for the plunger 8, improving the return response speed of the plunger 8, and significantly reducing the risk of the plunger 8 disengaging, which is beneficial to achieving high-speed operation of the fuel pump.

[0036] As a preferred solution, the pump body 1 is not provided with any inlet and outlet holes connected to external fuel oil pipes and engine oil pipes, ensuring that the structure of the pump body 1 has high integrity and sealing performance.

[0037] As a preferred solution, in combination with Figure 2 As shown in the figure, due to the adoption of an eccentric cam, the force application point of the plunger 8 will inevitably deviate from the central axis of the plunger 8 by a distance L, causing the plunger 8 to be subjected to a certain deflection moment during operation, increasing the risk of the plunger 8 component getting stuck. To improve the influence of the deflection moment on the plunger 8, in combination with Figure 3As shown in the figure, the axis of the plunger 8 is offset by a certain distance D2 relative to the central axis of the pump body 1. Finally, the force application point during the upward pumping stroke of the plunger 8 approaches the central axis of the plunger 8. By shortening the distance L between the force application point and the central axis of the plunger 8 to L1, the deflection moment on the plunger 8 is effectively reduced, avoiding the skew of the plunger 8 in the bushing 7 and preventing the jamming failure of the plunger 8 component.

[0038] As the rotational speed of the fuel supply pump continues to increase, after the linear velocity of the plunger 8 increases significantly, the temperature of the plunger 8 component also rises significantly. The increase in speed and temperature makes the clearance oil film of the plunger 8 component more likely to rupture on the one hand. Once the oil film is damaged, the balance of the supporting force of the plunger 8 is destroyed, leading to contact friction between the plunger 8 and the bushing 7, and finally the jamming of the plunger 8 component. On the other hand, it increases the system temperature and the thermal load significantly, which is not conducive to the safe operation of the system. For high-speed and high-pressure fuel supply pumps, this solution further optimizes the structure of the fuel pumping assembly. Specifically, in combination with Figure 4 As shown in the figure, the inner wall of the bushing 7 is provided with a groove 12. The bushing 7 is also provided with an oil inlet passage 13 and an oil return passage 14 that communicate with the groove 12, and the other ends of the oil inlet passage 13 and the oil return passage 14 communicate with the first cavity 4. Specifically, as Figure 1 shown in the figure, the oil inlet of the oil inlet passage 13 is roughly located in the middle position of the bushing 7, and the oil return port of the oil return passage 14 is located at the top of the bushing 7, so that the oil inlet area and the oil return port area are not connected to each other, ensuring forced lubrication with one-way flow and good lubrication of the plunger 8.

[0039] Figure 4 The arrow in the figure indicates the fuel flow direction. The plunger 8 component introduces low-temperature and low-pressure fuel into the groove 12 in the core area of the bushing 7 through the oil inlet passage 13 on the bushing 7 for effective lubrication and cooling of the plunger 8. Then, the heat generated by the plunger 8 component is taken away through the oil return passage 14, effectively controlling the system temperature, ensuring good lubrication between the plunger 8 and the bushing 7, and ensuring the stability and reliability of the operation of the plunger 8 component.

[0040] As a preferred solution, in combination with Figure 4 shown in the figure, the groove 12 is designed as an annular shape, and the oil inlet passage 13 and the oil return passage 14 are arranged circumferentially at intervals around the axis of the groove 12. Exemplarily, the oil inlet passage 13 and the oil return passage 14 are evenly distributed on the annular side of the groove 12. The meaning of even distribution is that the angle between adjacent two oil inlet passages 13 / adjacent two oil return passages 14 can be equal (i.e., Figure 4 shown in the figure), or the angle between the oil inlet passage 13 and the oil return passage 14 can be equal.

[0041] The purpose of setting a forced low-pressure circulating oil channel in the sleeve 7 is to allow low-temperature and low-pressure fuel to enter the groove 12 of the sleeve 7. On the one hand, it ensures that there is a certain thickness of oil film between the plunger 8 and the sleeve 7, which has a good lubrication effect and ensures the reliable movement function of the plunger 8 component; on the other hand, the flow of low-temperature fuel can absorb and remove the heat generated by the high-speed moving plunger 8, effectively ensuring that the plunger 8 component and the oil supply pump assembly operate at a suitable working temperature and improve the life of the oil supply pump. It can be seen that the main function of adopting this structure is to strengthen the lubrication and cooling of the plunger 8. In addition, the liquid pressure on the plunger 8 in the circumferential direction of the groove 12 is evenly distributed, reducing the influence of the lateral component of the forced lubricating oil pressure on the plunger 8 and causing it to deviate, ensuring that the plunger 8 is suspended in the hole of the sleeve 7, and reducing the risk of contact friction between the plunger 8 and the sleeve 7.

[0042] The high-speed high-pressure oil supply pump requires a higher response characteristic of the oil pump assembly, so the structure of the oil inlet valve 15, the oil outlet valve 16 and other components must have higher reliability, and the valve core opening and closing response speed must be faster. Figure 7 As shown, the oil inlet valve 15 and the oil outlet valve 16 are generally integrated into the plug sleeve 7 and placed on the top of the plunger 8, and arranged longitudinally in an overlapping manner. The low-pressure oil inlet and high-pressure oil outlet channels of the oil pump assembly are the same channel, and the opening and closing actions of the oil inlet valve 15 and the oil outlet valve 16 are linked; this arrangement scheme has poor responsiveness due to the overlapping placement of the oil inlet and outlet valves 16, and is only suitable for oil supply pumps with lower speeds. Once the speed increases, the oil supply efficiency of the oil supply pump will be greatly affected.

[0043] In view of the above problems, as a preferred solution, Figure 1 As described above, the oil inlet valve 15 and the oil outlet valve 16 are installed on the cover assembly in a "V" shape.

[0044] On the one hand, this solution makes the oil inlet valve 15 and the oil outlet valve 16 of the oil pump assembly close to the top of the plunger 8, which has a higher response characteristic, reduces the dead space volume of the oil pump assembly, improves the oil filling efficiency and oil supply efficiency of the oil pump assembly, and reduces the volume of the oil pump; on the other hand, the V-shaped inlet and outlet oil channels have good fluidity, which can effectively reduce the fluid resistance during the oil inlet and outlet process, and the oil channel does not have a large angle turn, which can reduce the risk of stress concentration and effectively improve the structural strength of the cover assembly. In addition, this solution makes the structure of the plug sleeve 7 simpler, and the plunger 8 and the plug sleeve 7 have simpler assembly processability.

[0045] As a preferred solution, Figure 5As shown in the figure, the eccentric cam assembly further includes a connecting block 17. The connecting block 17 is used to connect one end of the camshaft 5 with the fuel transfer pump. The clearance between the camshaft 5 and the adjacent mating part (i.e., the bearing) forms a first oil passage 18. A second oil passage 19 communicating with the first oil passage 18 is provided on the pump body 1. Specifically, the second oil passage 19 is machined at the bottom of the first cavity 3 inside the pump body 1. The first oil passage 18 and the second oil passage 19 guide the engine oil in the first cavity 3 into the connecting block 17, so that the engine oil forcibly lubricates the transmission connecting block 17 running at high speed, strengthens the lubrication and heat dissipation effect of the friction pair of the transmission connecting block 17, and improves the transmission reliability and service life of the transmission connecting block 17.

[0046] The present invention also provides an injection system, including the tappetless fuel transfer pump of any one of the above.

[0047] By canceling components with relatively large masses such as the tappet body 10, its roller 20 and the spring lower seat 11, the inertia brought by the mass under the spring is effectively reduced. The elastic member 9 only needs to ensure stable contact between the plunger 8 and the surface of the eccentric cam assembly, greatly reducing the restoring force required by the plunger 8, improving the return response speed of the plunger 8, and greatly reducing the risk of the plunger 8 disengaging, which is beneficial to achieving high-speed operation of the fuel transfer pump; thus improving the operation of the injection system.

[0048] By adopting the fuel transfer pump with a tappetless structure proposed by the present invention, it is especially suitable for enhancing the system working stability and the reliability of each component in the high-speed working range of the fuel transfer pump. The overall structure of the fuel transfer pump is compact and the installation space is small; the connecting block 17 of the plunger 8 of the fuel transfer pump is fully lubricated and cooled, enhancing the component reliability under high-speed working conditions; the fuel supply capacity of the high-speed high-pressure fuel transfer pump is stable and reliable, and the fuel supply efficiency is high; the tappetless 10 structure scheme effectively reduces the mass under the spring, enabling the fuel transfer pump to match a higher speed range and achieving the design goals of miniaturization and high power of the fuel transfer pump.

Claims

1. A tappetless oil supply pump, characterized in that: include: A body having an oil chamber, the oil chamber at least comprising a first chamber (3) for installing an eccentric cam assembly and a second chamber (4) for installing an oil pump assembly, the first chamber (3) and the second chamber (4) being communicated with each other, the oil pump assembly comprising a sleeve (7) installed in the body and a plunger (8) movably connected to the sleeve (7), the plunger (8) and the sleeve (7) being elastically connected via an elastic member (9), the eccentric cam assembly being in contact with the plunger (8) to lift the plunger (8).

2. The tappetless oil supply pump according to claim 1, characterized in that: The inner wall of the plug sleeve (7) is provided with a groove (12), and the plug sleeve (7) is also provided with an oil inlet passage (13) and an oil return passage (14) which are connected to the groove (12), and the other ends of the oil inlet passage (13) and the oil return passage (14) are connected to the second cavity (4).

3. The tappetless oil supply pump according to claim 2, characterized in that: The groove (12) is annular, and the oil inlet passage (13) and the oil return passage (14) are arranged at intervals in the circumferential direction around the axis of the groove (12).

4. The tappetless oil supply pump according to claim 3, characterized in that: The oil inlet passages (13) and / or the oil return passages (14) are evenly distributed.

5. A tappetless oil supply pump according to any one of claims 1 to 4, characterized in that: The main body comprises a cover assembly and a pump body (1), and also comprises an oil inlet valve (15) and an oil outlet valve (16); the oil inlet valve (15) and the oil outlet valve (16) are installed on the cover assembly in a "V" shape.

6. The tappetless oil supply pump according to claim 5, characterized in that: The eccentric cam assembly comprises a camshaft (5), one end of the camshaft (5) is connected to an oil delivery pump via a connecting block (17), a first oil passage (18) is provided between the camshaft (5) and an adjacent mating part, and the pump body (1) is provided with a second oil passage (19) connected to the first oil passage (18).

7. A fuel injection system, characterized in that: It comprises a tappetless oil supply pump according to any one of claims 1 to 6.

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