High-pressure fuel pump

Abstract

A high-pressure fuel pump includes: a drive shaft (2), and a vane pump (3) and a plunger pump (4) driven by the drive shaft, the vane pump being configured to supply pre-pressurized fuel to the plunger pump; wherein, the drive shaft includes a cam for driving a piston rod of the plunger pump such that the plunger pump alternately performs a fuel suction stroke and a fuel discharge stroke; the drive shaft further includes a shaft section for driving a rotor of the vane pump; the vane pump is configured such that, for each fuel suction stroke of the plunger pump, the vane pump provides a fuel supply cycle that is advanced by a phase angle relative to the fuel suction stroke.

Description

Technical Field

[0001] The present application relates to a high-pressure fuel pump with improved fuel supply performance of the fuel supply pump. Background Art

[0002] A typical high-pressure fuel pump includes a low-pressure component and a high-pressure component. The vane pump in the low-pressure component is used to supply fuel to the high-pressure component, and the plunger pump in the high-pressure component sucks in the fuel supplied by the vane pump, pressurizes the fuel to a high pressure, and outputs it.

[0003] This type of high-pressure fuel pump has a problem of insufficient fuel output capacity at certain speeds, especially in the high-speed range. The applicant has found that this problem is at least partly caused by the following reasons: namely, the phase synchronization of the fuel suction stroke of the plunger pump and the fuel supply cycle of the vane pump. During a fuel suction stroke of the plunger pump, the demand for the fuel suction volume by the plunger pump gradually rises to a peak and then decreases. During a fuel supply cycle of the vane pump, the fuel supply volume of the vane pump experiences a process of decreasing from a higher point to a bottom valley and then rising from the bottom valley. When the fuel suction stroke of the plunger pump is phase-synchronized with the fuel supply cycle of the vane pump, the bottom valley of the fuel supply volume of the vane pump corresponds in phase to the area where the fuel suction demand of the plunger pump is relatively high. Therefore, the fuel supply characteristics of the vane pump cannot match the fuel suction demand of the plunger pump, resulting in insufficient fuel output capacity of the high-pressure fuel pump. Summary of the Invention

[0004] The object of the present application is to solve the problem of insufficient fuel output capacity of the high-pressure fuel pump.

[0005] To this end, according to one aspect of the present application, there is provided a high-pressure fuel pump, including:

[0006] A drive shaft, and a vane pump and a plunger pump driven by the drive shaft, the vane pump being configured to supply pre-pressurized fuel to the plunger pump;

[0007] Wherein, the drive shaft includes a cam for driving a piston rod of the plunger pump so that the plunger pump executes a working cycle composed of alternating fuel suction strokes and fuel discharge strokes;

[0008] The drive shaft further includes a shaft section for driving a rotor of the vane pump;

[0009] The vane pump is configured such that, for each fuel suction stroke of the plunger pump, the vane pump provides a fuel supply cycle that is ahead of the fuel suction stroke by a leading phase angle.

[0010] According to a feasible embodiment, the vane pump is configured such that the starting point of each fuel suction stroke of the plunger pump falls within the bottom valley of a fuel supply cycle of the vane pump; and / or

[0011] The end point of the oil suction stroke falls within the valley bottom of a subsequent oil supply cycle of the vane pump.

[0012] According to a feasible embodiment, the vane pump includes a plurality of radially slidable vanes carried by the rotor, the plurality of vanes are evenly distributed at equal angular intervals, and the range of the leading phase angle is greater than 0° and less than half of the included angle between two adjacent vanes in the circumferential direction.

[0013] According to a feasible embodiment, the number of the vanes is 1 times or more than 1 times the number of working cycles completed by the plunger pump per revolution of the drive shaft, so that the number of oil supply cycles provided by the vane pump per revolution of the drive shaft is 1 times or more than 1 times the number of working cycles completed by the plunger pump.

[0014] According to a feasible embodiment, the oil suction stroke of the plunger pump starts from the top dead center of the piston rod, and each oil supply cycle of the vane pump starts when one of the plurality of vanes is located at the minimum clearance position between the rotor and the stator of the vane pump.

[0015] According to a feasible embodiment, when one of the vanes of the vane pump is positioned at the minimum clearance position between the rotor and the stator of the vane pump, the highest point of the cam lobe of the cam is set at a bias angle offset from the vertical direction in the reverse direction of the rotation direction of the drive shaft, and the value of the bias angle is equal to the leading phase angle.

[0016] According to a feasible embodiment, the piston rod of the plunger pump is oriented in the vertical direction, the shaft section is connected to the rotor by a key, the radial center line of the key bisects the included angle between two adjacent vanes in the circumferential direction, and when the radial center line of the key is in the vertical direction, one of the plurality of vanes is located at the minimum clearance position between the rotor and the stator of the vane pump.

[0017] According to a feasible embodiment, the plunger pump includes a single piston rod, the cam includes a pair of cam lobes (6) arranged opposite to each other for driving the piston rod, the number of the vanes is 4, the plunger pump completes two working cycles per revolution of the drive shaft, and the vane pump completes four oil supply cycles.

[0018] According to a feasible embodiment, when one of the vanes of the vane pump is positioned at the minimum clearance position between the rotor and the stator of the vane pump, the highest point of one of the pair of cam lobes is positioned at a bias of 20° - 35° from the vertical direction in the reverse direction of the rotation direction of the drive shaft, preferably about 30°.

[0019] According to a feasible implementation manner, the position of the minimum clearance between the rotor and the stator of the vane pump is set at a position deflected approximately 25° from the vertical direction along the rotation direction of the drive shaft.

[0020] According to the present application, the phase of the oil suction stroke of the plunger pump is delayed by an angle relative to the phase of the oil supply period of the vane pump, and this delay angle causes the peak value of the oil suction demand of the plunger pump to avoid the bottom of the oil supply volume of the vane pump. Therefore, the oil supply characteristics of the vane pump are as matched as possible with the oil suction demand of the plunger pump, thereby improving the fuel output capacity of the high-pressure fuel pump, especially the fuel output capacity in the high-speed range. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The foregoing and other aspects of the present application will be more fully understood and appreciated from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0022] Figure 1 is a schematic diagram of a high-pressure fuel pump according to a feasible implementation manner of the present application;

[0023] Figure 2 is Figure 1 an exploded view of the drive shaft and the main components of the vane pump used in the high-pressure fuel pump shown;

[0024] Figure 3 is to illustrate Figure 2 a schematic diagram showing an exemplary positional relationship between the drive shaft and the vane pump shown;

[0025] Figure 4 is to illustrate Figure 2 a schematic diagram showing another exemplary positional relationship between the drive shaft and the vane pump shown;

[0026] Figure 5 is a curve graph of the oil suction stroke of the plunger pump and the oil supply period of the vane pump that are matched in the high-pressure fuel pump of the present application;

[0027] Figure 6 is a curve graph showing the improvement effect of the fuel output capacity of the high-pressure fuel pump of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] Some embodiments of the present application will be described below with reference to the accompanying drawings. Figure 1 Illustrates the overall configuration of a feasible implementation manner of the high-pressure fuel pump of the present application, particularly a high-pressure diesel pump. The high-pressure fuel pump can be used to supply high-pressure fuel to an oil rail (not shown), and the oil rail then injects the fuel into an engine (not shown), particularly a diesel engine, via a nozzle.

[0029] Figure 1The high-pressure fuel pump therein mainly includes: a housing 1; a drive shaft 2 supported by the housing 1; and a vane pump 3 and a plunger pump 4 combined in the housing 1 and jointly driven by the drive shaft 2.

[0030] The main body portion of the drive shaft 2 is arranged substantially horizontally in the cavity formed in the housing 1 and is formed with a cam 5 for driving the plunger pump 4. The cam 5 includes a pair of cam lobes 6 that are circumferentially spaced 180° from each other and rotationally symmetric. The plunger pump 4 includes a tappet body 7 that reciprocates up and down following the cam 5, a piston rod 8 that is driven by the tappet body 7 to reciprocate up and down, and a return spring 9 that presses against the tappet body 7 around the piston rod 8. The return spring 9 keeps the roller 7a in the tappet body 7 in contact with the cam surface of the cam 5.

[0031] As the drive shaft 2 rotates, the cam surface of the cam 5 controls the plunger pump 4 to complete its working cycle, and each working cycle includes a successive oil discharge stroke and an oil suction stroke. In the oil discharge stroke, the cam lobe 6 presses the roller 7a, the tappet body 7 moves upward, and the piston rod 8 presses the fuel in the piston chamber of the plunger pump 4, causing the fuel to be discharged in a pressurized state. When the top dead center of the cam curve of the cam 5 (i.e., the top dead center of the piston rod 8) is reached, the oil discharge stroke ends, and then the oil suction stroke follows. In the oil suction stroke, under the action of the return spring 9, the tappet body 7 and the piston rod 8 move downward, the volume of the piston chamber becomes larger, and the fuel from the vane pump 3 is sucked into the piston chamber. The oil suction stroke starts from the top dead center of the cam curve of the cam 5 and ends at an angle after the top dead center, for example, equal to or less than 90°, depending on the shape of the cam lobe 6. In other words, the oil suction stroke can be connected to the starting point of the next oil discharge stroke or end at an angle before the starting point of the next oil discharge stroke. In the case where Figure 1 the cam 5 shown contains two cam lobes 6, the plunger pump 4 completes two working cycles for every 360° rotation of the drive shaft 2.

[0032] The end shaft section 10 of the drive shaft 2 is used to drive the vane pump 3. Specifically, the end shaft section 10 is connected to the rotor 12 of the vane pump 3 through a key 11. The vane pump 3 also includes a stator 13 eccentrically arranged around the rotor 12, and oil distribution discs 14, 15 located on the axial two sides of the rotor 12 and the stator 13.

[0033] Figure 2 The exploded view of the drive shaft 2 and the vane pump 3 is shown in. It can be seen that the key 11 is placed in the keyway 16 on the end shaft section 10 and the keyway 17 in the rotor 12. Four vanes 18 are slidably inserted into the corresponding vane slots 19 formed on the rotor 12.

[0034] The rotating drive shaft 2 drives the vane pump 3 to output fuel towards the side of the plunger pump 4. The fuel flow rate output by the vane pump 3 is not constant, but in a pulsating form. For every 360° rotation of the drive shaft 2, the vane pump 3 experiences four fuel output cycles. In each fuel output cycle, there are valleys and peaks in the fuel flow rate, as will be described in detail later.

[0035] Figure 3 An exemplary positional relationship between the cam 5 and the rotor 12, stator 13, and each vane 18 of the vane pump 3 is shown when looking along the central axis A of the drive shaft 2. It should be noted that Figure 3 It is only for the purpose of explanation, so it is not drawn to scale, and for clarity, some details are omitted.

[0036] Figure 3 In the figure, the X direction represents the vertical direction, and the piston rod 8 of the plunger pump 4 ( Figure 3 not shown in the figure) is arranged along the vertical direction X. The zero clearance (or minimum clearance) between the outer circumference of the rotor 12 of the vane pump 3 and the inner circumference of the stator 13 is defined as the 0° angular position of the rotor 12, and this 0° angular position is located at a position deflected by an angle α (α is equal to 45°) relative to the vertical direction X along the rotation direction R of the rotor 12 (i.e., the rotation direction of the drive shaft 2). At the starting point of each fuel output cycle of the vane pump 3, the four vanes 18 are respectively located at the 0°, 90°, 180° (the position of the maximum clearance from the stator 13), and 270° angular positions of the rotor 12.

[0037] The key 11 is set at the intermediate position between two vane slots 19, that is, the included angle between the radial center line of the key 11 and the radial center axis of any circumferentially adjacent vane 18 is 45°. When a vane 18 is located at the 0° angular position of the rotor 12, the radial center line of the key 11 is positioned above, or below, or to the left, or to the right of the central axis A of the drive shaft 2 along the vertical direction X or the horizontal direction. One of the four feasible positions of the key 11 (above the central axis A) is shown in Figure 3 the figure.

[0038] For this exemplary configuration, according to the prior art, the connection line O1O2 between the cam vertices O1 and O2 of the two cam lobes 6 of the cam 5 is parallel to the radial center line of the key 11; that is, at a top dead center of the cam curve of the cam 5, a vane 18 is located at the 0° angular position of the rotor 12, and the radial center line of the key 11 and the connection line O1O2 between the cam vertices of the cam lobe 6 are both oriented along the vertical direction X, thereby making the oil suction stroke of the plunger pump 4 phase-synchronized with a corresponding fuel supply cycle of the vane pump 3.

[0039] According to the present application, when a blade 18 is at the 0° angular position of the rotor 12, the line O1O2 between the cam vertices of the two cam lobes 6 of the cam 5 is offset from the vertical direction X by an angle β in the opposite direction of the rotation direction R of the rotor 12, and this offset angle β is greater than 0° and less than half of the angle between adjacent blades 18 in the circumferential direction.

[0040] It should be noted that the 0° angular position of the rotor 12 is not necessarily located at a position deflected by 45° from the vertical direction X along the rotation direction R of the rotor 12, but can be set at any suitable angle relative to the vertical direction X. For example, Figure 4 shows another exemplary positional relationship of the cam 5 and the rotor 12, stator 13, and each blade 18 of the vane pump 3 when viewed along the central axis A of the drive shaft 2. Similarly, it should be noted that Figure 4 is only for the purpose of explanation, and thus is not drawn to scale, and some details are omitted for clarity. In Figure 4 the example shown, the 0° angular position of the rotor 12 is located at an angle α that is deflected by approximately 25° from the vertical direction X along the rotation direction R of the rotor 12. Similar to Figure 3 the example shown, when a blade 18 is at the 0° angular position of the rotor 12, the line O1O2 between the cam vertices of the two cam lobes 6 of the cam 5 is offset from the vertical direction X by an angle β in the opposite direction of the rotation direction R of the rotor 12, and this offset angle β is greater than 0° and less than half of the angle between adjacent blades 18 in the circumferential direction.

[0041] Due to the existence of this offset angle β, the oil suction stroke of the piston pump 4 lags behind the corresponding oil supply cycle of the vane pump 3 by this angle β, so that the area with a higher oil suction demand of the piston pump 4 avoids the bottom of the oil supply of the vane pump 3.

[0042] The magnitude of this offset angle β can be determined by simulation or experiment so that the oil suction stroke of the piston pump 4 matches the oil supply cycle of the vane pump 3 as much as possible. For example, so that the areas with a higher oil suction demand of the piston pump 4 are all within the areas that can be satisfied by the oil supply capacity of the vane pump 3. For example, in Figure 3 、 Figure 4 the example, the offset angle β is set to 20° to 35°, preferably approximately 30°.

[0043] The improvement in the matching aspect between the oil suction stroke of the piston pump 4 and the oil supply cycle of the vane pump 3 in the present application can be seen from Figure 5 In Figure 5In it, the abscissa represents the rotation angle of the drive shaft 2 (i.e., the rotation angles of the rotor 12 and the cam 5), and the ordinate represents the oil suction demand of the piston pump 4 and the oil supply amount of the vane pump 3. The curve S0 in the figure represents the oil suction demand in an oil suction stroke of the piston pump 4, the curve S1 represents two oil supply cycles of the vane pump 3 in the prior art, and the curve S2 represents two oil supply cycles of the vane pump 3 of the present application.

[0044] From Figure 5 the comparison between the curves S0 and S1, it can be seen that according to the prior art, the oil suction stroke of the piston pump is in phase synchronization with one oil supply cycle of the vane pump, such that the interval with a large oil suction demand in this oil suction stroke of the piston pump falls at the bottom of the oil supply amount of the vane pump, thereby resulting in the oil supply capacity of the vane pump not meeting the oil suction demand of the piston pump, and the fuel output capacity of the high-pressure fuel pump being insufficient.

[0045] In contrast, from Figure 5 the comparison between the curves S0 and S2, it can be seen that according to the present application, the oil suction stroke of the piston pump lags behind the oil supply cycle of the vane pump by a phase angle β (e.g., 30°). That is, for each oil suction stroke of the piston pump, the vane pump can provide an oil supply cycle with a leading phase angle β. This makes the interval with a large oil suction demand in an oil suction stroke of the piston pump fall within the interval with a large oil supply amount of the vane pump. Preferably, the starting point of this oil suction stroke falls within the bottom of the previous oil supply cycle of the vane pump, and / or the ending point of this oil suction stroke falls within the bottom of the subsequent oil supply cycle of the vane pump. In this way, it can be made such that the oil supply capacity of the vane pump basically perfectly meets the oil suction demand of the piston pump, and the fuel output capacity of the high-pressure fuel pump is improved.

[0046] The improvement in the fuel output capacity of the high-pressure fuel pump of the present application can be seen from Figure 6 the experimental curves in Figure 6 In it, the horizontal axis represents the pump speed, i.e., the rotational speed of the drive shaft 2, and the vertical axis represents the fuel output amount of the high-pressure fuel pump. The curve Q1 is the fuel output amount of the high-pressure fuel pump according to the prior art at various pump speeds, and the curve Q2 is the fuel output amount of the high-pressure fuel pump according to the present application at various pump speeds. By comparing the two curves, it can be seen that in the high-speed range of the high-pressure fuel pump, especially in the range of 2000 rpm to 3600 rpm, the fuel output amount of the high-pressure fuel pump according to the present application is significantly improved compared to the prior art.

[0047] In addition, from Figure 6It can also be seen that, according to the prior art, in the range of 2400 rpm to 3200 rpm, as the pump speed increases, the fuel output of the high-pressure fuel pump does not increase correspondingly, which has a negative impact on the performance of the engine at high speeds. According to the present application, in the range of 1200 rpm to 3600 rpm, as the pump speed increases, the fuel output of the high-pressure fuel pump increases correspondingly, which improves the performance of the engine at high speeds.

[0048] Furthermore, from the above description, it can be seen that in the present application, for the oil suction stroke of the plunger pump, the corresponding oil supply period of the vane pump is advanced by an angle, so that when the plunger pump sucks oil, the output flow of the vane pump is relatively large, that is, the hydraulic pressure at the front end of the plunger pump during oil suction is relatively high. Therefore, the oil suction efficiency of the plunger pump can be improved, thereby improving the volumetric efficiency and fuel output capacity of the high-pressure fuel pump.

[0049] The scope of the present application is not limited to the specific embodiments described above, but can be implemented in a broader sense. The following describes the feasible embodiments of the present application in a broader sense.

[0050] Generally speaking, the high-pressure fuel pump of the present application may include one or more plunger pumps.

[0051] In the case of including multiple plunger pumps, the central axes of these plunger pumps can be arranged parallel to the central axis of the drive shaft, or distributed at equal angular intervals relative to the central axis of the drive shaft; for each plunger pump, a corresponding cam is provided on the drive shaft, and each cam can have one convex angle or multiple convex angles evenly distributed along the circumferential direction. The distribution of the plunger pump and the cam convex angle should be such that during one rotation of the drive shaft, all the working cycles (each including an oil suction stroke and an oil discharge stroke) of each plunger pump are distributed within 360° at equal intervals.

[0052] Assume that the high-pressure fuel pump of the present application includes n (n is an integer ≥ 1) plunger pumps, and each plunger pump is driven by m (m is an integer ≥ 1) cam convex angles. Then the total number of working cycles of each plunger pump during one rotation of the drive shaft is n*m. The number of vanes included in the vane pump is 1 times or more than the total number of working cycles of each plunger pump during one rotation of the drive shaft, that is, the number of vanes is n*m*k (k is an integer ≥ 1). In this way, for each oil suction stroke of the plunger pump, the vane pump can provide at least one oil supply period with a leading phase angle, so that during each oil suction stroke of the plunger pump, the vane pump can supply sufficient pre-pressurized fuel to the plunger pump. The degree of this leading phase angle is greater than 0° and less than half of the angle between a pair of adjacent vanes along the circumferential direction.

[0053] Considering that in actual machining, the cam lobe on the drive shaft is usually pre-formed, and then a keyway for connecting the key of the vane pump rotor is opened at a determined angular position. Therefore, according to the present application, based on the position where the minimum clearance between the rotor and the stator of the vane pump is determined and the lead phase angle of the vane pump, the angular position relationship between the key and the cam lobe can be determined, and then the keyway can be opened on the drive shaft. It should be noted that the number of feasible angular positions of the keyway is equal to the number of vanes, and one of these feasible angular positions can be selected as the actual angular position of the keyway.

[0054] It also needs to be pointed out at this point that in the prior art described above, the angular positions of the keyway on the drive shaft and the cam lobe are the same. According to the present invention, as described above, there is an association between the angular position of the cam lobe and the phase of the oil supply cycle of the vane pump rotor. After determining the eccentric position of the vane pump stator, the relationship between the angular position of the cam lobe and the phase of the vane pump rotor is determined, and the angular positions of the keyways on the drive shaft and the vane pump rotor can be determined subsequently. In other words, according to the present application, instead of directly determining the angular position relationship between the keyway on the drive shaft and the cam lobe when designing the drive shaft as in the prior art, it is necessary to determine the angular position of the keyway (key) based on the angular position of the cam lobe and considering the lead angle of the starting point of the vane pump oil supply cycle relative to the cam top dead center.

[0055] It also needs to be pointed out that although it is preferred to open the keyway on the vane pump rotor at the angular position exactly in the middle between two vane slots, this is not necessary. In fact, the keyway on the vane pump rotor can be opened at any angular position relative to the vane slot.

[0056] In summary, according to the present application, by aiming at the phase of the oil suction stroke of the plunger pump, there is a lead phase angle in the oil supply cycle provided by the vane pump. In this way, the oil supply cycle of the vane pump is matched with the oil suction stroke of the plunger pump, avoiding the situation in the prior art where the bottom of the oil supply volume of the vane pump corresponds to the area with a relatively high oil suction demand of the plunger pump in terms of phase, thereby improving the fuel output capacity of the high-pressure fuel pump.

[0057] Although the present application is described here with reference to specific exemplary embodiments, the scope of the present application is not limited to the details shown. Various modifications can be made to these details without departing from the basic principles of the present application.

Claims

1. A high-pressure fuel pump, comprising: a drive shaft (2), and a vane pump (3) and a plunger pump (4) driven by the drive shaft, wherein the vane pump is configured to supply pre-pressurized fuel to the plunger pump; wherein the drive shaft includes a cam (5) for driving a piston rod (8) of the plunger pump such that the plunger pump performs a working cycle consisting of alternating suction strokes and discharge strokes; the drive shaft further includes a shaft section for driving a rotor (12) of the vane pump; the vane pump is configured such that for each suction stroke of the plunger pump, the vane pump provides an oil supply cycle that is advanced by a lead phase angle relative to the suction stroke; wherein the vane pump includes a plurality of radially slidable vanes carried by the rotor, the plurality of vanes being evenly distributed at equal angular intervals, and the lead phase angle ranges from greater than 0° to less than half of the angle between two circumferentially adjacent vanes; 2. The high-pressure fuel pump according to claim 1, wherein, the vane pump is configured such that the start point of each suction stroke of the plunger pump falls within the bottom valley of an oil supply cycle of the vane pump; and / or the end point of the suction stroke falls within the bottom valley of a subsequent oil supply cycle of the vane pump.

3. The high-pressure fuel pump according to claim 1, wherein, The number of the vanes is 1 times or more than 1 times the number of working cycles completed by the plunger pump per revolution of the drive shaft, such that the number of oil supply cycles provided by the vane pump per revolution of the drive shaft is 1 times or more than 1 times the number of working cycles completed by the plunger pump.

4. The high-pressure fuel pump according to claim 3, wherein, The suction stroke of the plunger pump starts from the top dead center of the piston rod, and each oil supply cycle of the vane pump starts when one of the plurality of vanes is located at the minimum clearance position between the rotor and the stator of the vane pump.

5. The high-pressure fuel pump according to claim 4, wherein, When one of the vanes of the vane pump is positioned at the minimum clearance position between the rotor and the stator of the vane pump, the highest point of the cam lobe of the cam is set at a bias angle offset from the vertical direction in the reverse direction along the rotation direction of the drive shaft, and the value of the bias angle is equal to the lead phase angle.

6. The high-pressure fuel pump according to claim 4 or 5, wherein, The piston rod of the plunger pump is oriented in the vertical direction, the shaft section is connected to the rotor by a key (11), the radial center line of the key bisects the angle between two circumferentially adjacent vanes, and when the radial center line of the key is in the vertical direction, one of the plurality of vanes is located at the minimum clearance position between the rotor and the stator of the vane pump.

7. The high-pressure fuel pump according to claim 1, wherein, The plunger pump includes a single piston rod, the cam includes a pair of cam lobes (6) arranged opposite to each other for driving the piston rod, the number of the vanes is 4, the plunger pump completes two working cycles per revolution of the drive shaft, and the vane pump completes four oil supply cycles.

8. The high-pressure fuel pump according to claim 7, wherein, When one of the vanes of the vane pump is positioned at the minimum clearance position between the rotor and the stator of the vane pump, the highest point of one of the pair of cam lobes is positioned at an offset of 20° - 35° from the vertical direction in the reverse direction along the rotation direction of the drive shaft.

9. The high-pressure fuel pump according to claim 7, wherein, When one of the vanes of the vane pump is positioned at the minimum clearance position between the rotor and the stator of the vane pump, the highest point of one of the pair of cam lobes is positioned approximately 30º offset from the vertical direction in the reverse direction along the rotational direction of the drive shaft.

10. The high-pressure fuel pump according to claim 8 or 9, wherein, The minimum clearance position between the rotor and the stator of the vane pump is provided at approximately 25° deflected from the vertical direction along the rotational direction of the drive shaft.

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