High-pressure fuel pump capable of suppressing air intake

Abstract

A high-pressure fuel pump includes: a high-pressure assembly (1) for outputting fuel at high pressure, the high-pressure assembly including a fuel tank (10) and a fuel suction channel (6) having a fuel suction port connected to the fuel tank; and a low-pressure assembly (2) including a fuel pump (21) and a metering valve (8) for supplying fuel from the fuel pump to the high-pressure assembly in a metered manner; wherein the metering valve is equipped with an output channel (11) having a fuel delivery port connected to the upper part of the fuel tank.

Description

Technical Field

[0001] This application relates to a high-pressure fuel pump that can prevent excessive air intake during pump startup. Background Technology

[0002] Common rail technology plays a crucial role in meeting current and future emission standards in fuel injection systems used in diesel engines. Many automakers now include common rail diesel engines in their product lines. In fuel injection systems equipped with common rail systems, a high-pressure fuel pump supplies fuel at high pressure to the fuel rail.

[0003] like Figure 1 As shown, a conventional high-pressure fuel pump includes multiple plunger-type high-pressure components 1 for supplying high-pressure fuel to a fuel rail (not shown), and a low-pressure component 2, which includes a fuel pump (not shown) and a metering valve 8 for supplying low-pressure fuel from the fuel pump to the high-pressure components 1. The high-pressure component 1 has a fuel sump 10 for drawing in fuel, and the output passage 11 of the metering valve 8 leads to the lower part of the fuel sump 10.

[0004] When this high-pressure fuel pump stops operating, fuel in the pump may slowly leak through metering valve 8, allowing air to enter the pump. After a prolonged period of inactivity, such as overnight, the fuel level in the pump may drop to [a lower level]. Figure 1 As shown in the figure, the liquid level A near the lower end of the oil tank 10 is filled with air above the liquid level A in the high-pressure assembly 1, which causes the starting performance of the high-pressure fuel pump to deteriorate. Summary of the Invention

[0005] The purpose of this application is to suppress the amount of fuel leakage, i.e., the amount of air entering, when the high-pressure fuel pump stops operating.

[0006] Therefore, according to one aspect of this application, a high-pressure fuel pump is provided, comprising: a high-pressure assembly for outputting fuel at high pressure, the high-pressure assembly including a fuel sump and a suction channel having a suction port connected to the fuel sump; and a low-pressure assembly including a fuel pump and a metering valve for supplying fuel from the fuel pump to the high-pressure assembly in a metering manner; wherein the metering valve is equipped with an output channel having a fuel delivery port connected to the upper part of the fuel sump.

[0007] According to one feasible implementation, the oil delivery port faces the upper end of the oil tank; optionally, the position of the oil suction port is lower than that of the oil delivery port.

[0008] According to one feasible embodiment, the oil suction channel is a straight channel extending at an angle or horizontally, or a combination of segments extending in different directions.

[0009] According to one feasible implementation, the output channel is a straight channel extending at an angle or horizontally, or a combination of segments extending in different directions.

[0010] According to one feasible embodiment, the high-pressure component and the low-pressure component are combined in a common pump housing, and the output channel is formed in the pump housing.

[0011] According to one feasible embodiment, the high-pressure assembly includes a plunger sleeve installed in a plunger sleeve bore in the pump housing and a plunger that reciprocates within the plunger sleeve, the output channel being formed in the pump housing by drilling a hole from the plunger sleeve bore toward the oil outlet port of the metering valve.

[0012] According to one feasible embodiment, the plunger sleeve has an axially extending plunger cavity and a valve mounting cavity communicating with the plunger cavity above the plunger cavity, and the oil groove is formed on the outer periphery of the plunger sleeve; optionally, the oil suction channel is formed in the plunger sleeve and extends from the oil suction port to the valve mounting cavity.

[0013] According to one feasible embodiment, the high-pressure assembly further includes an oil suction valve and an oil discharge valve arranged in a valve mounting cavity, wherein the valve seat of the oil suction valve abuts against a step formed between the plunger cavity and the valve mounting cavity, and the upper end of the oil groove faces the valve seat of the oil suction valve radially upward.

[0014] According to one feasible embodiment, the oil suction channel extends from the oil suction port to the step.

[0015] According to one feasible embodiment, a lubrication channel is also formed in the plunger sleeve, leading from the oil groove to the outer periphery of the plunger, and the oil suction port is connected to the oil groove above the connection position between the lubrication channel and the oil groove.

[0016] According to one feasible embodiment, the high-pressure fuel pump is a high-pressure fuel pump for a diesel engine common rail system.

[0017] According to this application, the outlet of the metering valve is connected to the fuel sump of the high-pressure component at the upper part (preferably above the fuel inlet of the high-pressure component). This ensures that even if fuel leaks through the metering valve when the high-pressure fuel pump stops operating, the residual fuel level in the fuel sump remains at a high level, reducing the amount of air entering the high-pressure fuel pump. Furthermore, when the high-pressure fuel pump restarts, the amount of air drawn into the high-pressure component can be reduced, and it may even draw in fuel first rather than air, thus improving the starting performance of the high-pressure fuel pump. Attached Figure Description

[0018] The foregoing and other aspects of this application will be more fully understood and appreciated through the following detailed description with reference to the accompanying drawings, in which:

[0019] Figure 1This is a partial cross-sectional view of a high-pressure fuel pump based on existing technology.

[0020] Figure 2 This is an overall structural diagram of a high-pressure fuel pump according to one feasible embodiment of the present application.

[0021] Figure 3 yes Figure 2 A partial cross-sectional view of the high-pressure fuel pump in the image.

[0022] Figure 4 This is a partial cross-sectional view of a high-pressure fuel pump according to another feasible embodiment of this application.

[0023] Figure 5 This is a partial cross-sectional view of a high-pressure fuel pump according to another feasible embodiment of the present application. Detailed Implementation

[0024] Figure 2 A high-pressure fuel pump according to one embodiment of this application is shown. Figure 3 A partial configuration of the high-pressure fuel pump is shown. (As shown) Figure 2 , 3 As shown, the high-pressure fuel pump mainly includes: at least one high-pressure component 1 for supplying fuel at high pressure to the fuel rail (not shown), and a low-pressure component 2 for supplying fuel to the high-pressure component 1. The low-pressure component 2 includes a fuel pump 21 for drawing fuel from the fuel tank (not shown) and pre-pressurizing the fuel, and a metering valve 8 for metering the fuel from the fuel pump 21 to the high-pressure component 1. The high-pressure component 1 and the low-pressure component 2 are integrated into a common pump housing 20.

[0025] The high-pressure component 1 is in the form of a plunger pump, mainly including: a plunger sleeve 3 installed in the plunger sleeve hole of the pump housing 20, the plunger sleeve 3 having an axially extending plunger cavity 3a and a valve mounting cavity 3b above the plunger cavity 3a and communicating with the plunger cavity 3a; a plunger 4 driven by the camshaft 13 to reciprocate in the plunger cavity 3a of the plunger sleeve 3; and an oil suction valve 5 and an oil discharge valve 7, respectively in the form of one-way valves, assembled in the valve mounting cavity 3b of the plunger sleeve 3.

[0026] An axial section of the outer periphery of the plunger sleeve 3 is recessed to form an annular oil groove 10. The valve mounting cavity 3b is connected to the oil groove 10 through an oil suction channel 6 formed in the plunger sleeve 3. In this example, there are two or more oil suction channels 6, distributed around the lower part of the valve mounting cavity 3b. The oil suction channels 6 extend approximately horizontally from the valve mounting cavity 3b and connect to the upper part of the oil groove 10. The part of the oil suction channel 6 that connects to the oil groove 10 is called the oil suction port of the oil suction channel 6.

[0027] Regarding the various parts of the oil groove 10, in terms of height, the middle part of the oil groove 10 refers to the mid-plane perpendicular to the central axis of the oil groove 10 (i.e., the central axis of the plunger sleeve 3). The part above the mid-plane of the oil groove 10 is called the upper part of the oil groove 10, and the part below the mid-plane of the oil groove 10 is called the lower part of the oil groove 10.

[0028] The suction valve 5 mainly includes a valve ball 5a and a valve seat 5b. The valve seat 5b is arranged immediately above and adjacent to the plunger cavity 3a, and the valve ball 5a sits on the valve seat port of the valve seat 5b. A first channel 5c is formed in the valve seat 5b to establish communication between the suction channel 6 and the valve seat port, and a second channel 5d to establish communication between the plunger cavity 3a and the upper space of the valve seat 5b (leading to the discharge valve 7).

[0029] Metering valve 8 is disposed in pump housing 20 on the low-pressure component 2 side, and pump housing 20 also has an input channel 9 and an output channel 11 for metering valve 8. Thus, the oil inlet port of metering valve 8 is connected to the output end of fuel pump 21 through input channel 9, and the oil outlet port of metering valve 8 is connected to fuel tank 10 through output channel 11. When the high-pressure fuel pump is working, metering valve 8 is reciprocated to periodically open and close the connection between input channel 9 and output channel 11.

[0030] Furthermore, a lubrication channel 12 is formed in the plunger sleeve 3, leading from the oil groove 10 to the outer periphery of the plunger 4, so as to lubricate the plunger 4 with fuel. The axial position of the lubrication channel 12 in the plunger sleeve 3 should be ensured that the lubrication channel 12 still faces the plunger 4 at the final retraction position of the plunger 4.

[0031] When the high-pressure fuel pump is operating, fuel output from the fuel pump 21 is supplied to the fuel sump 10 of the high-pressure assembly 1 in a metered manner through the output channel 11 via the reciprocating opening and closing of the metering valve 8. Simultaneously, the plunger 4 reciprocates to draw in and discharge fuel. Specifically, when the plunger 4 retracts, the suction valve 5 opens due to the pressure difference across the valve ball 5a, and fuel is drawn from the fuel sump 10 into the plunger chamber 3a through the suction channel 6, the first channel 5c, and the second channel 5d. Then, when the plunger 4 advances, the fuel in the plunger chamber 3a is pressurized, and the suction valve 5 closes due to the pressure difference across the valve ball 5a. The fuel in the plunger chamber 3a is discharged to the fuel rail via the second channel 5d and the discharge valve 7.

[0032] In the case where the high-pressure fuel pump has multiple high-pressure components 1, these high-pressure components 1 are arranged side by side, and their oil tanks 10 are connected by corresponding channels, so that each high-pressure component 1 can be supplied with fuel by the fuel pump 21 through the metering valve 8.

[0033] In the circumferential direction, the oil groove 10 can form a complete annulus around the entire outer circumference of the plunger sleeve 3, or a partial annulus around a portion of the outer circumference of the plunger sleeve 3. In the axial direction, the lower end of the oil groove 10 communicates with the lubrication channel 12; the upper end preferably faces the valve seat 5b radially, for example, above the first channel 5c in the valve seat 5b.

[0034] The output channel 11 of the metering valve 8 is connected to the upper part of the oil tank 10. Specifically, as shown in the figure, the output channel 11 is an inclined straight channel, including a first port 11a facing the output side of the metering valve 8 and a second port (which can be referred to as the oil supply port of the metering valve 8) 11b communicating with the upper part of the oil tank 10. The second port 11b is positioned higher than the first port 11a. The second port 11b faces the upper part of the oil tank 10.

[0035] Because the output channel 11 extends obliquely upward from its first port 11a to its second port 11b, even if the high-pressure fuel pump stops operating for a long time, causing fuel to leak through the output channel 11 and input channel 9 (returning to the fuel tank) and air to enter the output channel 11 and input channel 9, some fuel will still remain in the fuel sump 10. Even in the case of maximum leakage, the level A of the residual fuel in the fuel sump 10 will remain at the lowest point of the second port 11b. Figure 3 As shown. Thus, a considerable amount of fuel will still remain in the fuel tank 10. Relative to... Figure 1 As shown, when the high-pressure fuel pump of this application restarts, the amount of air drawn in by the high-pressure component 1 will decrease, so the starting performance of the high-pressure fuel pump is less affected by the air drawn in.

[0036] In the illustrated example, the second port 11b of the output channel 11 is positioned lower than the suction port of the suction channel 6. According to a modification, the second port 11b is positioned higher than the suction port of the suction channel 6 (i.e., the second port 11b faces the upper end of the fuel sump 10). In this modification, the suction channel 6, plunger chamber 3a, and valve mounting chamber 3b can remain filled with fuel for an extended period. When the high-pressure fuel pump is not operating for a long time, the amount of air entering the fuel sump 10 can be further reduced, thereby further reducing the impact of intake air on the starting performance of the high-pressure fuel pump.

[0037] According to this application, the output channel 11 can be configured in other forms. Regardless of the specific form of the output channel 11, it is sufficient that its second port 11b faces the upper part of the oil tank 10 (especially the upper end of the oil tank 10). The second port 11b is preferably higher than the oil suction port of the oil suction channel 6.

[0038] For example, according to Figure 4In the illustrated embodiment, the output channel 11 includes a vertical segment starting at a first port 11a and a horizontal segment connecting to the vertical segment and ending at a second port 11b. The second port 11b faces the upper part of the oil tank 10. The second port 11b may be higher than the oil suction port of the oil suction channel 6 (i.e., the second port 11b faces the upper end of the oil tank 10), as shown in the figure, or the second port 11b may be lower than the oil suction port of the oil suction channel 6. Besides including the combination of the vertical and horizontal segments described above, the output channel 11 may also include any combination of vertical, horizontal, and inclined segments.

[0039] Figure 4 Other aspects of the implementation methods in Figure 2 , 3 Similar or identical items shown will not be described again.

[0040] according to Figure 4 In the illustrated embodiment, since the second port 11b faces the upper part of the oil tank 10 (shown as facing the upper end of the oil tank 10), even if fuel leaks through the output channel 11 and the input channel 9, the fuel level inside the high-pressure assembly 1 will generally only drop to level A, corresponding to the lowest point of the second port 11b. Thus, a considerable amount of fuel will still remain in the oil tank 10. Relative to... Figure 1 As shown, when the high-pressure fuel pump of this application restarts, the air intake of the high-pressure component 1 will decrease, so the starting performance of the high-pressure fuel pump is less affected by the intake air.

[0041] Furthermore, this application can modify the oil suction channel 6 to lower the position of its oil suction port, thereby further improving the starting performance of the high-pressure fuel pump.

[0042] For example, Figure 5 This illustration shows another feasible embodiment of the high-pressure fuel pump of this application, wherein the oil suction channel 6 is an inclined channel formed in the plunger sleeve 3, which includes a first port (suction port) 6a communicating with the lower part of the oil groove 10 and a second port 6b communicating with the valve mounting cavity 3b. The second port 6b is positioned higher than the first port 6a. The first port 6a is located above the connection between the lubrication channel 12 and the oil groove 10. The second port 6b opens at the stepped portion between the valve mounting cavity 3b and the plunger cavity 3a.

[0043] The oil suction channel 6 may include multiple oil suction channels 6 distributed around the plunger cavity 3a.

[0044] The output channel 11 of the metering valve 8 is an inclined channel formed in the pump housing 20 on one side of the low-pressure assembly 2, including a first port 11a facing the output side of the metering valve 8 and a second port 11b communicating with the upper part of the oil sump 10. The second port 11b is positioned higher than the first port 11a. The second port 11b may face the upper part, especially the upper end, of the oil sump 10. The output channel 11 can be formed by drilling a hole in the pump housing 20 for installing the plunger sleeve 3 (at which point the plunger sleeve 3 is not yet installed) toward the oil outlet port of the metering valve 8.

[0045] It is understandable that output channel 11 in this example could also be designed similarly. Figure 4 The forms shown include vertical and horizontal segments, or even any combination of vertical, horizontal, and inclined segments. In this embodiment, regardless of the specific form of the output channel 11, its second port 11b is higher than the first port 6a of the oil suction channel 6.

[0046] Figure 5 Other aspects of the implementation method are the same as those in the example. Figure 2 , 3 Similar or identical items shown will not be described again.

[0047] exist Figure 5 In the illustrated embodiment, due to the connection position between the fuel suction channel 6 and the output channel 11 and the fuel tank 10, even if the high-pressure fuel pump stops operating for a long time, causing fuel leakage in the low-pressure assembly 2 and air entering the output channel 11 and the input channel 9, fuel will still remain in the fuel tank 10. The fuel level A remaining in the fuel tank 10 will at most drop to the lowest point of the second port 11b. Thus, a considerable amount of fuel will still remain in the fuel suction channel 6 and the fuel tank 10. (Comparison) Figure 1 As can be seen, the amount of fuel remaining in the high-pressure fuel pump in this example is significantly increased. This ensures that the fuel intake port of high-pressure assembly 1 always faces a certain amount of fuel. When the high-pressure fuel pump restarts, high-pressure assembly 1 draws in fuel first, rather than air. This facilitates the establishment of initial pressure in high-pressure assembly 1, allowing the high-pressure fuel pump to quickly reach a stable operating state, thereby improving the starting performance of the high-pressure fuel pump.

[0048] Based on the fundamental principles of this application, those skilled in the art can make specific designs for the structure of the oil suction channel 6, the output channel 11, and the oil tank 10 according to the specific style of the high-pressure fuel pump.

[0049] For example, in the illustrated example, the oil groove 10 is a recess formed on the outer periphery of the plunger sleeve 3; however, the oil groove 10 can also be formed inside the plunger sleeve 3, and the oil delivery port of the metering valve 8 can be connected to the oil groove 10 via a corresponding channel in the plunger sleeve 3. Alternatively, the oil groove 10 can be formed in the pump housing 20 around the outer periphery of the plunger sleeve 3; or, the oil groove 10 can be a combination of a recess formed on the outer periphery of the plunger sleeve 3 and a recess formed in the pump housing 20.

[0050] Other modifications can also be conceived.

[0051] According to this application, since the fuel delivery port of the metering valve is positioned higher than that of the prior art, even if there is fuel leakage in the high-pressure assembly, the fuel level in the fuel tank can always be maintained at a certain height (above the middle plane of the fuel tank), thereby increasing the fuel flow rate in the high-pressure assembly and reducing the amount of space entering due to fuel leakage. This results in a smaller amount of air being drawn into the high-pressure assembly when the high-pressure fuel pump is restarted after it has stopped (especially after a long period of inactivity), and it may even always draw in fuel first, thus improving the starting performance of the high-pressure fuel pump.

[0052] The oil suction channel and the output channel in this application can be straight channels, or they can be composed of two or more segments extending in different directions, such as horizontal segments and / or vertical segments and / or inclined segments.

[0053] This application is particularly applicable to high-pressure fuel pumps in common rail systems for diesel engines. However, it is understood that this application can also be applied to other types of high-pressure fuel pumps.

[0054] While this application has been described herein with reference to specific embodiments, the scope of this application is not limited to the details shown. Various modifications may be made to these details without departing from the basic principles of this application.

Claims

1. A high-pressure fuel pump, comprising: A high-pressure assembly (1) is used to output fuel at high pressure. The high-pressure assembly includes an oil groove (10) formed on the outer periphery of a plunger sleeve (3) and an oil suction channel (6) formed in the plunger sleeve (3). The oil suction channel (6) has an oil suction port connected to the oil groove (10). An axially extending plunger cavity (3a) and a valve mounting cavity (3b) communicating with the plunger cavity (3a) above the plunger cavity (3a) are formed in the plunger sleeve (3). A plunger (4) reciprocates in the plunger cavity (3a). The valve mounting cavity (3b) is connected to the oil groove (10) through the oil suction channel (6). A lubrication channel (12) is also formed in the plunger sleeve (3) leading from the oil groove (10) to the outer periphery of the plunger (4). as well as The low-pressure component (2) includes a fuel pump (21) and a metering valve (8) for metering fuel from the fuel pump to the high-pressure component. The high-pressure component and the low-pressure component are combined in a common pump housing, and the metering valve is equipped with an output channel (11), which is an inclined straight channel formed in the pump housing and has an oil delivery port connected to the upper part of the oil tank (10).

2. The high-pressure fuel pump as described in claim 1, wherein, The oil delivery port faces the upper end of the oil tank.

3. The high-pressure fuel pump as described in claim 2, wherein, The position of the oil suction port is lower than that of the oil delivery port.

4. The high-pressure fuel pump as described in claim 1, wherein, The oil suction channel is a straight channel extending at an angle or horizontally, or a combination of segments extending in different directions.

5. The high-pressure fuel pump according to any one of claims 1 to 4, wherein, The plunger sleeve (3) is installed in the plunger sleeve hole of the pump housing, and the output channel is formed in the pump housing by drilling a hole from the plunger sleeve hole toward the oil outlet port of the metering valve.

6. The high-pressure fuel pump according to any one of claims 1 to 4, wherein, The oil suction channel extends from the oil suction port and leads to the valve mounting cavity.

7. The high-pressure fuel pump as claimed in claim 6, wherein, The high-pressure assembly also includes an oil suction valve (5) and an oil discharge valve (7) arranged in the valve mounting cavity. The valve seat (5b) of the oil suction valve (5) abuts against the step formed between the plunger cavity and the valve mounting cavity. The upper end of the oil groove faces the valve seat of the oil suction valve in the radial direction.

8. The high-pressure fuel pump as claimed in claim 7, wherein, The oil suction channel extends from the oil suction port to the step.

9. The high-pressure fuel pump according to any one of claims 1 to 4, wherein, The oil suction port is connected to the oil trough above the connection point between the lubrication channel and the oil trough.

10. The high-pressure fuel pump according to any one of claims 1 to 4, wherein, The high-pressure fuel pump is a high-pressure fuel pump for the common rail system of a diesel engine.

Images