CN111350622B

CN111350622B - High-pressure pump

Info

Publication number: CN111350622B
Application number: CN201911289034.6A
Authority: CN
Inventors: 今村凌大
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 2018-12-20
Filing date: 2019-12-13
Publication date: 2023-05-23
Anticipated expiration: 2039-12-13
Also published as: CN111350622A; JP2020101100A; JP7205211B2; DE102019127935A1

Abstract

The high-pressure pump (101) includes a cylinder (20) and a plunger (25) slidably provided in the cylinder (20), and pressurizes and discharges fuel flowing from the fuel inlet (41) into the pressurizing chamber (24) by operation of the plunger. The high-pressure pump (101) has a leakage fuel collection passage (60) that collects leakage fuel that leaks from the pressurizing chamber (24) through a gap between the cylinder (20) and the plunger (25) and discharges the leakage fuel to the outside of the cylinder (20). In the fuel collection passage (60), when a portion where the leaked fuel flows is defined as an upstream portion and a portion where the leaked fuel is discharged is defined as a downstream portion, the leaked fuel collection passage (60) communicates with the fuel inlet (41) only in the downstream portion.

Description

High-pressure pump

Technical Field

The present invention relates to a high pressure pump.

Background

Conventionally, a high-pressure pump has a leakage fuel collection passage that collects leakage fuel that leaks through a gap between a cylinder and a plunger and discharges the leakage fuel from a pressurizing chamber to the outside.

For example, in the fuel supply device disclosed in patent document 1, an annular leakage collecting groove is formed on an inner wall of a plunger insertion hole in a cylinder. The fuel flowing into the fuel gallery is supplied to the leakage collection groove via the fuel bypass passage. The fuel flowing into the leakage collecting tank is returned to the fuel tank through the return passage hole and the return fuel pipe. The return passage hole communicates with the fuel gallery through a relief passage hole.

Prior art literature

Patent document 1 JP 2016-142197A

Disclosure of Invention

The axial direction of the plunger is defined as the vertical direction of the cylinder, the side of the pumping chamber is defined as the upper part of the cylinder, and the side opposite to the pumping chamber is defined as the lower part of the cylinder. In patent document 1, a return passage hole connecting the leakage collecting tank and the return fuel pipe and formed in the lower portion of the cylinder corresponds to a "leakage fuel collecting passage". The downstream portion of the return passage hole located at the upper portion of the cylinder communicates with the fuel inlet through the pressure release passage hole. An upstream portion of the return passage hole located in the lower portion of the cylinder communicates with the fuel inlet from the leakage collection groove via a fuel bypass passage.

Hereinafter, in the present specification, "high temperature" and "low temperature" with respect to the temperature of the fuel refer to the relative temperatures. While the temperature of the plunger sliding on the cylinder inner wall is raised, the cylinder lower portion is cooled as low-temperature fuel flows from the fuel tank into the upstream portion of the leak fuel collection passage. As a result, due to the difference in thermal expansion, the gap between the outer wall of the high Wen Zhusai and the inner wall of the low temperature cylinder can be reduced, thereby having the possibility of plunger failure.

The present invention has been made in view of the above-described problems, and an object of the present invention is to reduce a temperature difference between a plunger and a cylinder in an upstream portion of a leak fuel collection passage and to prevent the plunger from malfunctioning.

The present invention is a high-pressure pump that includes a cylinder and a plunger slidably provided in the cylinder and pressurizes and discharges pressurized fuel by operation of the plunger, the fuel flowing from a fuel inlet into a pressurizing chamber.

The high-pressure pump has a leakage fuel collection passage that collects leakage fuel that leaks from the pressurizing chamber through a gap between the cylinder and the plunger and discharges the leakage fuel to the outside of the cylinder. In the leakage fuel collection passage, when a portion where leakage fuel flows is defined as an upstream portion and a portion on a side where leakage fuel is discharged is defined as a downstream portion, the leakage fuel collection passage communicates with the fuel inlet only at the downstream portion.

In the present invention, since the low-temperature fuel does not flow into the upstream portion of the leakage fuel collection passage, the leakage fuel in the lower portion of the cylinder is not cooled. Therefore, the heat of the high-temperature leak fuel is easily transferred to the lower portion of the cylinder. Therefore, the temperature difference between the plunger and the cylinder can be reduced, and an appropriate gap can be maintained. Therefore, malfunction of the plunger can be prevented.

On the other hand, the low-temperature fuel flows from the fuel inlet into the downstream portion of the leaked fuel collection passage, thereby cooling the leaked fuel discharged to the outside of the high-pressure pump, and reducing the burden on the return fuel cooling device.

Drawings

FIG. 1 is an overall block diagram of a common rail system to which a high-pressure pump according to an embodiment is applied;

fig. 2 is a sectional view of the high-pressure pump according to the first embodiment;

fig. 3 is a schematic cross-sectional view of a high-pressure pump according to a first embodiment;

FIG. 4 is a schematic top view of a high pressure pump according to a first embodiment;

fig. 5A is a temperature analysis chart of a cylinder and a plunger of the high-pressure pump according to the comparative example;

fig. 5B is a temperature analysis chart of the cylinder and plunger of the high-pressure pump according to the present embodiment;

fig. 6 is a schematic cross-sectional view of a high-pressure pump according to a second embodiment;

FIG. 7 is a schematic top view of a high pressure pump according to a second embodiment;

fig. 8 is a schematic cross-sectional view of a high-pressure pump according to a third embodiment;

FIG. 9 is a schematic top view of a high pressure pump according to a third embodiment;

fig. 10 is a schematic cross-sectional view of a high-pressure pump according to a fourth embodiment;

FIG. 11 is a schematic top view of a high pressure pump according to a fourth embodiment; and

fig. 12 is a schematic cross-sectional view of a high-pressure pump according to a fifth embodiment.

Detailed Description

Hereinafter, various embodiments of the high-pressure pump will be described with reference to the accompanying drawings. In the various embodiments, the same reference numerals are used for substantially the same elements, and descriptions thereof will be omitted. The following first to fifth embodiments are collectively referred to as "the present embodiment". The present embodiment is a high-pressure pump that is applied to, for example, a diesel engine and supplies high-pressure fuel to a common rail.

[ common rail System ]

First, the overall configuration of the common rail system will be described with reference to fig. 1. The common rail system includes: a fuel tank 1, a high-pressure pump 10 (or a supply pump), a common rail 8, a plurality of fuel injection valves 12, and the like, and each of the components is connected by a pipe. The fuel tank 1 and the high-pressure pump 10 are connected by a low-pressure fuel pipe 2, and a fuel filter 3 for removing foreign substances is provided in the middle of the low-pressure fuel pipe 2. The high-pressure pump 10 and the common rail 8 are connected by a rail front high-pressure fuel pipe 7. The common rail 8 and the plurality of fuel injection valves 12 are connected by a plurality of rail rear high-pressure fuel pipes 11.

The high-pressure pump 10 pressurizes low-pressure fuel drawn from the fuel tank 1, and supplies the high-pressure fuel to the common rail 8. The high-pressure fuel supplied to the common rail 8 is distributed to a plurality of (four in the embodiment of fig. 1) fuel injection valves 12. The fuel injection valve 12 injects fuel into a cylinder of the engine. It should be noted that the configuration of the control system and the description of its operation will be omitted.

The return line 14 returns the return fuel that is not consumed by the injection to the fuel tank 1. The relief line 6 is connected between the high-pressure pump 10 and the return line 14, the relief line 9 is connected between the high-pressure pump 10 and the common rail 8, and the leakage line 13 is connected between the high-pressure pump 10 and the fuel injection valve 12. In the present embodiment, attention is paid to the return fuel discharged from the high-pressure pump 10 to the return pipe 14 through the overflow pipe 6.

[ high pressure Pump ]

Next, the construction and operational effects of the high-pressure pump 10 will be described for each embodiment. Since the structure and operation of the high-pressure pump 10 of the present embodiment other than those related to the leaked fuel collection passage 60 are substantially the same as those of the fuel supply device described in patent document 1 (JP 2016-142197A), a detailed description will be omitted in the following description. In the reference numerals of the high-pressure pump of each embodiment, the third digit number after "10" indicates the number of the embodiment.

(first embodiment)

The high-pressure pump 101 of the first embodiment will be described with reference to fig. 2 to 5. As shown in fig. 2, the high-pressure pump 101 changes the volume of the pressurizing chamber 24 by sliding the plunger 25 inserted into the plunger hole 23 of the cylinder 20. Hereinafter, according to the vertical direction in fig. 2, the side of the plunger hole 23 on which the pressurizing chamber 24 is provided is referred to as an upper side, and the side opposite to the pressurizing chamber 24 is referred to as a lower side. The plunger 25 reciprocates in the vertical direction along the plunger hole 23. In the case where the high-pressure pump 101 is actually mounted on an engine block or the like, the moving direction of the plunger 25 is not limited to a strict vertical direction, and the high-pressure pump 101 may be mounted so that the moving direction of the plunger is inclined.

A sheet 29 urged downward by a spring 28 is attached to the lower end portion of the plunger 25. Rotation of a cam shaft (not shown) is transmitted to the lower end portion of the plunger 25, so that the plunger 25 rises against the urging force of the spring 28. Accordingly, the fuel flowing from the fuel inlet 41 into the pressurizing chamber 24 is pressurized and discharged to the common rail 8. The discharge opening for the high-pressure fuel is not shown in the section of fig. 2 and is shown in fig. 3 and 4.

The body 31 of the solenoid valve portion 30 is accommodated in a valve body accommodating portion 21 formed above the cylinder 20. In the body 31, a valve passage 32 having an opening 33 is formed which extends in the radial direction and communicates with the pressurizing chamber 24. As described below, the valve passage 32 corresponds to a volume chamber having a function other than the function of a communication passage between the fuel inlet 41 and the downstream portion of the leak fuel collection passage 60. The term "volume chamber" used herein is a term used as a generic concept, which means "a space constituting a part of a communication passage" rather than a name of a lower part.

A damper 42 for suppressing pulsation of fuel is mounted on the damper mounting portion 22 of the cylinder 20. The fuel flowing in from the fuel inlet 41 reaches the valve passage 32 via the damper 42. When the valve is open, the valve body 35 opens the opening 33 of the valve passage 32; and when the valve is closed, the valve body 35 is seated on the valve seat portion 34 and closes the opening 33, so that the valve body 35 regulates the fuel sucked into the pressurizing chamber 24. Above the cylinder 20, a coil 36, a stator core 37, an armature 38, a spring guide stopper 39, and the like constituting the solenoid valve section 30 are provided.

A cover 26 is provided at a lower portion of the cylinder 20 and an oil seal 27 sealing an outer periphery of the plunger 25 is fixed by the cover 26. The leakage fuel leaking from the pressurizing chamber 24 through the gap between the inner wall of the cylinder 20 and the outer wall of the plunger 25 is accumulated in the annular space above the oil seal 27.

The cylinder 20 has a leakage fuel collection passage 60, the leakage fuel collection passage 60 communicates the annular space with a return fuel outlet 68 and the leakage fuel is discharged to the outside of the cylinder 20 in the leakage fuel collection passage 60. In other words, the annular space forms a "collection channel inlet 61" in which the leaked fuel flows into the leaked fuel collection channel 60. In the leaked fuel collection passage 60, the portion on the side where the leaked fuel flows is referred to as an "upstream portion", and the portion where the leaked fuel is discharged is referred to as a "downstream portion".

In the leakage fuel collection passage 60 according to the first embodiment, the valve portion communication passage 43 that communicates from the valve passage 32 is joined to the joint 66 located in the downstream portion. That is, the downstream portion of the leaked fuel collection passage 60 communicates with the fuel inlet 41 via the valve portion communication passage 43 and the valve passage 32. A hole 45 is provided in the valve portion communication passage 43 immediately before the joint portion 66. The diameter and length of the hole 45 are appropriately set. On the other hand, in the upstream portion of the leak fuel collection passage 60, a passage communicating to the fuel inlet 41 is not formed. In short, the leaked fuel collection passage 60 communicates with the fuel inlet 41 only at the downstream portion.

In addition, the leakage fuel collection passage 60 of the first embodiment is constituted by connecting an upstream side flow passage 63 and a downstream side flow passage 64 having different angles with respect to the axis of the plunger 25. In other words, the leakage fuel collection passage 60 has a shape in which the upstream side flow passage 63 and the downstream side flow passage 64 are curved and connected to each other.

In addition, in fig. 2, the Z-axis is defined along the axis of the plunger 25, and the upper end position of the pressurizing chamber 24 is described as "0", and the position of the collecting channel inlet 61 is described as "a". These descriptions are used in the descriptions of fig. 5A and 5B.

Next, reference is made to the schematic cross-sectional view of fig. 3 and the schematic top view of fig. 4. Figures of other embodiments are also described with reference to figures 3 and 4. Fig. 3 shows a schematic view of the path of the axial section of the high-pressure pump 101, in particular of the fuel flow. The embodiment shown in fig. 3 differs from the embodiment shown in fig. 2 mainly in that a discharge passage 46, a discharge valve 47, and a discharge port 48 are shown, and in that the solenoid valve portion 30 and the damper 42 are simplified. When fuel is sucked and regulated, the discharge valve 47 is closed by a spring force. When the plunger 25 rises and the pressure exerted by the fuel pressure in the pressurizing chamber 24 exceeds the spring force of the discharge valve 47, the discharge valve 47 opens and the high-pressure fuel is discharged to the outside through the discharge passage 46 from the discharge port 48 to the outside.

Fig. 4 schematically shows the path of the fuel with respect to the radial cross-sectional flow seen from above the high-pressure pump 101. Fig. 4 is a schematic cross-sectional view in the radial direction, more precisely, but for convenience it is referred to as "schematic plan view". The pressurizing chamber 24 is formed at the center of the cylinder 20, and the fuel inlet 41, the discharge port 48, and the return fuel outlet 68 are appropriately provided in the circumferential direction. These settings are not exact, only indicating that they are in place without interfering with each other. In addition, the path represented by a straight line in the schematic plan view is not necessarily formed straight, but the path represented by a multi-segment line in the schematic plan view may be formed straight in practice.

At the center of the cylinder 20, the valve body 31 is indicated by a thin broken line, and the valve passage 32 and the opening 33 are indicated by solid lines. Further, the plenum 24 located below the valve passage 32 and the discharge passage 46 communicating from the plenum 24 with the discharge port 48 are indicated by broken lines. The cross section of the valve body 35 in the opening 33 of the valve channel 32 is not shown. A damper 42 is schematically shown between the fuel inlet 41 and the valve passage 32. When the valve body 35 is opened, the fuel flowing from the fuel inlet 41 into the valve passage 32 through the damper 42 is supplied from the opening 33 to the pressurizing chamber 24 at the rear of the drawing. The fuel flowing into the valve passage 32 merges with the leaking fuel via the valve portion communication passage 43 and the hole 45 at a junction 66 located at a downstream portion of the leaking fuel collecting passage 60. The joined fuel is discharged from the return fuel outlet 68.

As described above, in the first embodiment, in addition to the original function of the "volume chamber" in the metering valve, the valve passage 32 of the body 31 serves as the "communication passage between the fuel inlet 41 and the downstream portion of the leak fuel collection passage 60". That is, the high-pressure pump 101 of the first embodiment shares the valve passage 32, which is the "volume chamber" of the metering valve, as the "communication passage between the fuel inlet 41 and the downstream portion of the leak fuel collection passage 60".

As described above with reference to fig. 2, in the leakage fuel collection passage 60 of the first embodiment, the upstream side flow passage 63 and the downstream side flow passage 64 having different angles with respect to the axis of the plunger 25 are connected. Specifically, a first angle θ1 formed by the upstream-side flow passage 63 and the axis of the plunger 25 is smaller than a second angle θ2 formed by the downstream-side flow passage 64 and the axis of the plunger 25. That is, an upstream side flow passage 63 is formed oppositely along the plunger hole 23 and a downstream side flow passage 64 is formed away from the plunger hole 23. In fig. 2, the downstream-side flow passage 64 is inclined with respect to the axis of the plunger 25, and satisfies a relationship of the first angle θ1 < the second angle θ2 < 90 °. However, the downstream-side flow passage 64 may be formed orthogonal to the axis of the plunger 25 (i.e., "second angle θ2=90°").

In addition, since the upstream side flow passage 63 and the downstream side flow passage 64 are generally manufactured by drilling, the cross section is circular. The diameter D1 of the upstream side flow channel 63 is smaller than the diameter D2 of the downstream side flow channel 64. Even if the cross-sectional shape of the flow channel is not strictly circular, for example, if the flow channel is elliptical, the average of the major and minor axes may be considered as the diameter.

Next, referring to fig. 5, the effects of the present embodiment will be described in comparison with the comparative example. As described in the "summary of the invention" column, "high temperature" and "low temperature" in this specification refer to relative temperatures with respect to the temperature of the fuel. The high-pressure pump of the comparative example has such a configuration: wherein the fuel inlet is connected to an upstream portion of the leak fuel collection passage and low-temperature fuel is introduced from the fuel tank into the vicinity of the collection passage inlet 61. The high-pressure pump disclosed in the drawing of DE 102017204843B3 in germany corresponds to a comparative example, for example.

The fuel supply device disclosed in fig. 1 and the like of patent document 1 (JP No. 2016-142197A) communicates with a fuel inlet at both an upstream portion and a downstream portion of a leak fuel collection passage, and the configuration of the supply device is different from that of the comparative example.

The horizontal axis in fig. 5A and 5B represents a position on the Z-axis shown in fig. 2. "0" on the Z axis is the upper end position of the pressurizing chamber 24, and "a" on the Z axis is the position of the collection passage inlet 61 corresponding to the upper side of the oil seal 27. Near 0, which is the upper portion of the cylinder 20 on the Z-axis, the fuel just flowing from the fuel inlet 41 into the pressurizing chamber 24 has a relatively low temperature. As the value near the lower portion of the cylinder 20 and on the Z axis increases, the increase in the temperature of the leaked fuel due to the sliding between the plunger 25 and the cylinder 20 is transmitted, so that both the plunger temperature and the cylinder temperature rise. At point "a" of high Wen Xielou fuel accumulation on the Z axis, the temperature becomes highest.

In the comparative example shown in fig. 5A, since the cylinder is cooled by the low-temperature fuel flowing from the fuel inlet to the upstream portion of the leak fuel collection passage, the cylinder temperature decreases and the temperature difference between the cylinder temperature and the plunger temperature increases. As a result, the gap between the outer wall of the high Wen Zhusai and the inner wall of the low temperature cylinder is reduced due to the thermal expansion difference, and there is a risk of plunger failure.

On the other hand, in the present embodiment shown in fig. 5B, since the low-temperature fuel does not flow into the upstream portion of the leaked fuel collection passage 60, the leaked fuel at the lower portion of the cylinder 20, that is, at the position near "a" is not cooled. Therefore, the heat of the high-temperature leak fuel is easily transferred to the lower portion of the cylinder 20. Accordingly, the temperature difference between the plunger 25 and the cylinder 20 can be reduced, and an appropriate gap can be maintained. Therefore, the plunger 25 can be prevented from malfunctioning.

On the other hand, low-temperature fuel flows from the fuel inlet 41 into the downstream portion of the leaked fuel collection passage 60, thereby cooling the leaked fuel discharged to the outside of the high-pressure pump 101 and reducing the burden on the return fuel cooling device. In addition, the high-pressure pump 101 of the first embodiment has the following effects.

The fuel inlet 41 and the downstream portion of the leak fuel collection passage 60 communicate via the valve passage 32 that is a "volume chamber having a function other than the function as a communication passage". In other words, the valve passage 32 is included in a portion of the path connecting the fuel inlet 41 and the downstream portion of the leak fuel collection passage 60. Therefore, the volume chambers having other functions can be effectively shared without providing a dedicated communication passage in the high-pressure pump 101.

The leakage fuel collection passage 60 is constituted by sequentially connecting an upstream side flow passage 63 and a downstream side flow passage 64 having different angles with respect to the axis of the plunger 25. Thus, the degree of freedom in the layout of the leakage fuel collection passage 60 can be increased according to the position of the return fuel outlet 68 and the convenience of hole processing.

In particular, in the first embodiment, the first angle θ1 formed by the upstream-side flow passage 63 and the axis of the plunger 25 is smaller than the second angle θ2 formed by the downstream-side flow passage 64 and the axis of the plunger 25. Since the upstream-side flow passage 63 through which the high-temperature leak fuel flows is close to the plunger hole 23, the lower portion of the cylinder 20 is effectively heated, so that the temperature difference between the plunger 25 and the cylinder 20 can be made small. In addition, since the diameter D1 of the upstream-side flow passage 63 is smaller than the diameter D2 of the downstream-side flow passage 64, the fuel flow rate at the lower portion of the cylinder 20 can be increased, and the heat transfer coefficient at the lower portion of the cylinder 20 can be improved.

Further, a hole 45 is provided in the valve portion communication passage 43 that communicates the fuel inlet 41 and the downstream portion of the leak fuel collection passage 60. If the amount of fuel returned through the valve portion communication passage 43 is too large compared to the amount of fuel required to cool the leaked fuel, the proportion of fuel to be pumped is reduced. That is, since the fuel sucked into the pressurizing chamber 24 is reduced, the discharge amount required for the high-pressure pump 101 cannot be discharged. Therefore, by providing the hole 45 in the valve portion communication passage 43, the amount of fuel that merges into the leak fuel collection passage 60 can be appropriately adjusted.

(second embodiment)

Fig. 6 and 7 show a high-pressure pump 102 according to a second embodiment. In the second embodiment, the shape and the like of the leakage fuel collection passage 60 of the first embodiment are simplified. That is, the leakage fuel collection passage 60 is formed in a single diameter and straight line from the upstream portion to the downstream portion. Further, the damper 42 located between the fuel inlet 41 and the valve passage 32 is omitted, and the hole 45 is not provided in the valve portion communication passage 43.

In short, the high-pressure pump 102 of the second embodiment realizes at least "a configuration in which only the downstream portion of the leak fuel collection passage 60 communicates with the fuel inlet 41". By adopting at least the configuration shown in fig. 6 and 7, the temperature difference between the plunger 25 and the cylinder 20 is reduced and the proper clearance between the plunger 25 and the cylinder 20 is maintained. Therefore, the plunger 25 can be prevented from malfunctioning. Further, in the second embodiment, since the leakage fuel collection passage 60 having a single diameter can be processed in a straight line, the processing man-hour can be reduced.

(third embodiment)

Fig. 8 and 9 show a high-pressure pump 103 according to a third embodiment. The third embodiment is different from the second embodiment in that a passage communicating from the fuel inlet 41 to a downstream portion of the leak fuel collection passage 60. That is, the fuel inlet 41 and the downstream portion of the leakage fuel collection passage 60 communicate directly via the dedicated side flow communication passage 44. Here, the side flow in the "side flow communication passage" means only the side flow with respect to the main flow when the valve portion communication passage 43 passing through the valve passage 32 is regarded as the "main flow" passage. That is, the position where the communication passage is formed is not limited. In fig. 8 and 9, the side-flow communication channel 44 is schematically shown as being bent at a plurality of locations, but in practice it may be formed into a shape that can be machined or is easy to machine.

In fig. 8 and 9, the downstream portions of the valve passage 32 and the leakage fuel collection passage 60 may not communicate with each other, or the valve portion communication passage 43 may be formed as indicated by a long-dashed two-dot chain line. When the valve portion communication passage 43 is not formed, the fuel inlet 41 and the downstream portion of the leak fuel collection passage 60 communicate only through the side flow communication passage 44. Further, when the valve portion communication passage 43 is formed, the fuel inlet 41 and the leak fuel collection passage 60 communicate with each other so as to flow through the side flow communication passage 44 and the valve portion communication passage 43 in parallel.

In the third embodiment, since the dedicated side flow communication passage 44 that communicates the fuel inlet 41 and the downstream portion of the leak fuel collection passage 60 is formed, the low-temperature fuel can be supplied from the fuel inlet 41 to the downstream portion of the leak fuel collection passage 60 more stably. In the third embodiment, similar to the first embodiment, a plurality of flow passages having different angles with respect to the axis of the plunger 25 may be connected. Further, the diameters of the plurality of flow channels may be changed, or holes may be provided in the side flow communication channel 44.

(fourth embodiment)

Fig. 10 and 11 show a high-pressure pump 104 according to a fourth embodiment. In the fourth embodiment, in comparison with the third embodiment, a damper 51 or a valve 52 is provided in the middle of the side flow communication passage 435. The damper 51 basically has a pulsation suppressing function as the damper 42 shown in fig. 2, but is different in installation position. Further, the valve 52 opens and closes the side flow communication passage 435, and the specific configuration is not limited. The volume chambers in the damper 51 and the valve 52 correspond to "volume chambers having functions other than the function as a communication passage between the fuel inlet 41 and the downstream portion of the leak fuel collection passage 60". Therefore, unlike the side-flow communication channel 44 of the third embodiment, the side-flow communication channel 435 of the fourth embodiment may not correspond to a "dedicated communication channel". In this way, the communication passage between the fuel inlet 41 and the downstream portion of the leak fuel collection passage 60 may be configured in any form.

(fifth embodiment)

The high-pressure pump 105 of the fifth embodiment shown in fig. 12 has two leak

fuel collection passages

601 and 602 that communicate with the return fuel outlet 68 from different positions in the circumferential direction of the collection passage inlet 61, respectively. Each of the leakage

fuel collection channels

601 and 602 includes an upstream

side collection channel

631 and 632 having a relatively small angle with respect to the axis of the plunger 25 and a downstream

side collection channel

641 and 642 having a relatively large angle with respect to the axis of the plunger 25.

Similarly, three or more leakage fuel collection passages may be formed. Since a plurality of leak fuel collection passages are formed at different positions in the circumferential direction of the collection passage inlet 61, circumferential deviation of the leak fuel discharge amount can be reduced. Therefore, the cylinder temperature can be made relatively uniform in the circumferential direction.

(other embodiments)

(A) In contrast to the first embodiment, the first angle θ1 formed by the upstream-side flow passage 63 and the axis of the plunger 25 may be greater than the second angle θ2 formed by the downstream-side flow passage 64 and the axis of the plunger 25. In this case, the effect of reducing the temperature difference between the plunger 25 and the cylinder 20 cannot be expected. However, the following effects can be similarly obtained: the degree of freedom in the arrangement of the leakage fuel collection passage 60 can be increased according to the position of the return fuel outlet 68 and drilling can be performed easily.

(B) Contrary to the first embodiment, the leakage fuel collection passage 60 may be constituted by sequentially connecting three or more flow passages having different angles with respect to the axis of the plunger 25, as long as it can be machined.

(C) The upstream-side flow passage 63 and the downstream-side flow passage 64 in the first embodiment are each formed in a straight shape, that is, formed to have a single diameter D1, D2 of constant diameter. On the other hand, for example, the leak fuel collection passage 60 may be formed in a tapered state in which the leak fuel collection passage continuously expands from the upstream portion to the downstream portion. Even in this configuration, the diameter of the leakage fuel collection passage 60 on the upstream side is smaller than that on the downstream side. Accordingly, the flow rate of fuel in the lower portion of the cylinder 20 increases and the heat transfer coefficient of the lower portion of the cylinder 20 increases.

(D) The configurations relating to the leak fuel collection passage and the communication passage of each of the above-described embodiments may be used in appropriate combination as long as they are not contradictory.

(E) The high-pressure pump of the present invention is not limited to a diesel engine, and may be used as a fuel pump for fuel injection or other fuels.

The present disclosure is not limited to the above-described embodiments, and various modifications may be employed within the scope of the present disclosure without departing from the spirit of the present disclosure.

Claims

1. A high pressure pump, comprising:

a cylinder (20);

a solenoid valve portion (30) that is provided on a fuel inlet (41) and operates a valve body (35) to open and close an opening (33) of a valve passage (32) formed in the body (31) for regulating an amount of fuel sucked into a pressurizing chamber (24) from the fuel inlet;

a plunger (25) configured to be slidably disposed in the cylinder; and

a plenum (24) into which fuel flows from a fuel inlet (41),

wherein the high-pressure pump pressurizes and discharges the fuel in the pressurizing chamber by operation of the plunger, further comprising

A leakage fuel collection passage (60, 601, 602) configured to collect leakage fuel leaking from the pressurizing chamber through a gap between the cylinder and the plunger and to discharge the leakage fuel to an outside of the cylinder, wherein,

when the portion on the side where the leaked fuel flows in the leaked fuel collection passage is defined as an upstream portion and the portion on the side where the leaked fuel is discharged is defined as a downstream portion,

the leakage fuel collection passage communicates with the fuel inlet only at the downstream portion,

the leakage fuel collection passage is configured to connect an upstream side flow passage (63) and a downstream side flow passage (64) having different angles with respect to an axis of the plunger,

a first angle (θ1) formed by the upstream side flow passage and the axis of the plunger is less than a second angle (θ2) formed by the downstream side flow passage and the axis of the plunger,

the valve passage is included as a volume chamber provided in at least a part of a passage (43) that communicates the fuel inlet and the downstream portion of the leaked fuel collection passage, and the volume chamber is shared as a communication passage.

2. The high pressure pump of claim 1, wherein,

the leakage fuel collection passage has a diameter (D1) on the upstream portion that is smaller than a diameter (D2) on the downstream portion.

3. The high-pressure pump according to claim 1 or 2, wherein,

a hole (45) is provided in a passage communicating with the fuel inlet and a downstream portion of the leaked fuel collection passage.

4. The high-pressure pump according to claim 1 or 2, wherein,

the leakage fuel collection passage has a plurality of the leakage fuel collection passages (601, 602).