High-pressure pipe

Abstract

To provide a high-pressure pipe that can shorten the injection period in close-range, multi-stage injection. [Solution] The high-pressure pipe 1 is installed between the injector C and the common rail B of a diesel engine A and is a high-pressure pipe for supplying high-pressure fuel F from the common rail B to the injector C. The high-pressure pipe 1 is equipped with a passage 12 through which the high-pressure fuel F flows. The passage 12 has a first passage 121 through which the high-pressure fuel F flows in a first direction D1, and a second passage 122 through which the high-pressure fuel F flows in a second direction D2 different from the first direction D1.

Description

Technical Field

[0001] The present invention relates to a high-pressure pipe.

Background Art

[0002] Patent Document 1 describes a fuel injection control device. This fuel injection control device causes a fuel injection valve of a diesel engine to execute main injection and a plurality of after-injections as fuel injection into a combustion chamber. The main injection is, for example, an injection executed when the piston is at the top dead center position. The after-injection is an injection executed after the main injection. The total injection amount for outputting a required torque from a driver is divided into the main injection and the plurality of after-injections and injected.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As described in Patent Document 1 above, proximity-decrement multi-stage injection including main injection and after-injection is an effective means for improving thermal efficiency. Therefore, a proposal for a configuration for suitably realizing such injection is desired.

[0005] On the other hand, there is a demand to shorten the total injection period of proximity-decrement multi-stage injection. However, during fuel injection, pressure drop and pulsation occur in the high-pressure pipe between the common rail and the injector, so the interval for pressure recovery until the start of the small injection after the main injection becomes long, and there is a problem that it is difficult to shorten the total injection period.

[0006] Therefore, an object of the present invention is to provide a high-pressure pipe capable of shortening the injection period of proximity-decrement multi-stage injection. [Means for solving the problem]

[0007] The high-pressure pipe according to the present invention is provided between the injector and the common rail of an engine and is for supplying high-pressure fuel from the common rail to the injector, and is equipped with a passage for circulating high-pressure fuel, the passage having a first passage for circulating high-pressure fuel in a first direction and a second passage for circulating high-pressure fuel in a second direction different from the first direction.

[0008] This high-pressure pipe is installed between the common rail and the injector and has a passage for circulating high-pressure fuel. The passage has a first passage for circulating the high-pressure fuel in a first direction and a second passage for circulating the high-pressure fuel in a second direction different from the first direction. As a result, in this high-pressure pipe, the path length of the high-pressure fuel can be extended to a length that includes at least the first passage and the second passage, compared to the distance that linearly connects the introduction and outlet of the high-pressure fuel. According to the inventor's findings, by increasing the path length of the high-pressure fuel, a phenomenon occurs in which pressure pulsation is less likely to attenuate, making it possible to maintain a high injection pressure after the main injection. Therefore, with this high-pressure pipe, the interval for pressure recovery after the main injection can be shortened, and the injection period of close-range reduction multi-stage injection can be shortened.

[0009] The high-pressure pipe according to the present invention includes a partition member that divides the internal space such that the internal space forming the flow path includes a first portion and a second portion communicating with the first portion, and a first flow path may be formed in the first portion and a second flow path may be formed in the second portion. In this case, by dividing the internal space of the high-pressure pipe with the partition member, the first portion and the second portion providing the first and second flow paths are formed in the internal space. Thus, it is possible to increase the path length of the high-pressure fuel while suppressing an increase in the overall length of the high-pressure pipe.

[0010] In the high-pressure pipe according to the present invention, the high-pressure pipe extends in a straight line, the first direction is from one direction of extension of the high-pressure pipe to the other, and the second direction is from the other direction of extension to the one direction. The partition member partitions the internal space such that the internal space includes a first portion extending along the extension direction, a second portion extending along the extension direction and communicating with the first portion, and a third portion extending along the extension direction and communicating with the second portion. A first flow path may be formed in the first portion and the third portion. In this case, it is possible to increase the path length of the high-pressure fuel while reliably suppressing an increase in the overall length of the high-pressure pipe. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a high-pressure pipe that can shorten the injection period of close-range multi-stage injection. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a schematic diagram showing a part of a vehicle to which the high-pressure pipe according to this embodiment is applied. [Figure 2] Figure 2 is a perspective view showing the high-pressure pipe shown in Figure 1. [Figure 3] Figure 3 is an exploded perspective view of the high-pressure pipe shown in Figure 2. [Figure 4] Figure 4 is a cross-sectional view along the line IV-IV in Figure 3. [Figure 5] Figure 5 is a graph showing a comparative example in which the high-pressure pipe according to this embodiment is not applied to the fuel line between the common rail and the injector. [Figure 6] Figure 6 is a graph showing the case where the high-pressure pipe according to this embodiment is applied to the fuel line between the common rail and the injector. [Figure 7] Figure 7 is a graph illustrating the improvement in thermal efficiency. [Modes for carrying out the invention]

[0013] An embodiment will be described below with reference to the drawings. In the description of the drawings, the same or equivalent elements will be denoted by the same reference numeral, and redundant explanations may be omitted.

[0014] Figure 1 is a schematic diagram showing a part of a vehicle to which the high-pressure pipe according to this embodiment is applied. As shown in Figure 1, the vehicle (not shown) to which the high-pressure pipe 1 is applied is, for example, equipped with a diesel engine (engine) A, which is an internal combustion engine that uses light oil as fuel. The diesel engine A is equipped with an injector C that injects high-pressure fuel F into the combustion chamber (not shown). In this vehicle, the injector C performs close-proximity multi-stage injection, including main injection and multiple after-injections.

[0015] The high-pressure pipe 1 is installed between the common rail B and the injector C of the vehicle. More specifically, a fuel line L is provided between the common rail B and the injector C to supply high-pressure fuel F to the injector C, and the high-pressure pipe 1 constitutes at least a part of the fuel line L. Therefore, the high-pressure pipe 1 is for supplying high-pressure fuel F from the common rail B to the injector C.

[0016] Figure 2 is a perspective view showing the high-pressure pipe shown in Figure 1. Figure 3 is an exploded perspective view of the high-pressure pipe shown in Figure 2. Figure 4 is a cross-sectional view along line IV-IV in Figure 3. As shown in Figures 2-4, the high-pressure pipe 1 has a pipe body 10 and a partition member 20. The pipe body 10, for example, has a cylindrical shape that extends in a straight line. Therefore, the high-pressure pipe 1 also extends in a straight line. The direction in which the high-pressure pipe 1 and the pipe body 10 extend is called the extending direction De. The pipe body 10 includes a cylindrical internal space 11 that extends along the extending direction De. The internal space 11 forms a flow path 12 for the high-pressure fuel F.

[0017] The partition member 20 is fitted into the internal space 11 and extends linearly along the extending direction De inside the internal space 11. The partition member 20 includes a first wall portion 22 and a second wall portion 23. The first wall portion 22 has a flat plate shape extending along the extending direction De. Also, when viewed from the extending direction De, the first wall portion 22 extends from one of a pair of opposed regions of the inner wall surface of the internal space 11 to the other.

[0018] The second wall portion 23 has a flat plate shape extending along the extending direction De. The second wall portion 23 is erected on the first wall portion 22. That is, when viewed from the extending direction De, the second wall portion 23 extends from a partial region of the first wall portion 22 to a partial region of the inner wall surface of the internal space 11 facing the said region. Thereby, the partition member 20 partitions the internal space 11 into a first portion 25, a second portion 26, and a third portion 27.

[0019] When viewed from the extending direction De, the first portion 25 is defined by one wall surface of the first wall portion 22, one wall surface of the second wall portion 23, and the region of the inner wall surface of the internal space 11 facing those wall surfaces. When viewed from the extending direction De, the second portion 26 is defined by one wall surface of the first wall portion 22, the other wall surface of the second wall portion 23, and the region of the inner wall surface of the internal space 11 facing the wall surfaces. When viewed from the extending direction De, the third portion 27 is defined by the other wall surface of the first wall portion 22 and the region of the inner wall surface of the internal space 11 facing the said other wall surface.

[0020] As an example, the position of the connection portion between the first wall portion 22 and the inner wall surface of the internal space 11, the positional relationship between the first wall portion 22 and the second wall portion 23, and the position of the connection portion between the second wall portion 23 and the inner wall surface of the internal space 11 may be set so that the cross-sectional areas in a cross-section (the cross-section of FIG. 4) intersecting (orthogonal) to the extending direction De of the first portion 25, the second portion 26, and the third portion 27 are substantially equal.

[0021] The pipe body 10 has one end 10a in the extending direction De and the other end 10b in the extending direction De. High-pressure fuel F is introduced into the internal space 11 from the end 10a side and discharged from the internal space 11 at the end 10b side.

[0022] The partition member 20 further includes lid portions 28 and 29 provided at each end of the partition member 20 in the extending direction De. The lid portion 28 is provided on the first wall portion 22 and the second wall portion 23 at one end of the partition member 20 in the extending direction De (i.e., the end portion 10a of the pipe body 10) so as to close off everything except the first portion 25 when viewed from the extending direction De. The lid portion 29 is provided on the first wall portion 22 and the second wall portion 23 at the other end of the partition member 20 in the extending direction De (i.e., the end portion 10b of the pipe body 10) so as to close off everything except the third portion 27 when viewed from the extending direction De.

[0023] Furthermore, a communication hole 23h is formed at the other end of the second wall portion 23 in the extending direction De, connecting the first portion 25 and the second portion 26. In addition, a communication hole 22h is formed at one end of the first wall portion 22 in the extending direction De, connecting the second portion 26 and the third portion 27. Therefore, the first portion 25 and the second portion 26 are in communication with each other via the communication hole 23h, and the second portion 26 and the third portion 27 are in communication with each other via the communication hole 22h.

[0024] Thus, the partition member 20 partitions the internal space 11 such that the internal space 11 includes a first portion 25 extending along the extending direction De, a second portion 26 extending along the extending direction De and communicating with the first portion 25, and a third portion 27 extending along the extending direction De and communicating with the second portion 26.

[0025] In the high-pressure pipe 1 configured as described above, high-pressure fuel F is introduced into the first portion 25 exposed from the cover portion 28 at the end 10a of the pipe body. The high-pressure fuel F introduced into the first portion 25 flows from one end to the other in the extending direction De and flows into the second portion 26 through the communication hole 23h of the second wall portion 23. The high-pressure fuel F that has flowed into the second portion 26 flows from the other end to the other in the extending direction De and flows into the third portion 27 through the communication hole 22h of the first wall portion 22. The high-pressure fuel F that has flowed into the third portion 27 flows from one end to the other in the extending direction De and is led out from the third portion 27 exposed from the cover portion 29 at the end 10b of the pipe body 10.

[0026] Therefore, the flow path 12 formed in the high-pressure pipe 1 includes a first flow path 121 formed in the first section 25 that allows high-pressure fuel F to flow in a first direction D1 from one end of the extending direction De to the other; a second flow path 122 formed in the second section 26 that allows high-pressure fuel F to flow in a second direction D2 (a different direction from the first direction D1 and opposite to the first direction D1) from the other end of the extending direction De to the other; and a first flow path 123 in the third section 27 that allows high-pressure fuel F to flow in the first direction D1, similar to the first flow path 121.

[0027] In other words, the flow path 12 of the high-pressure fuel F is folded back an even number of times (twice in this case) within the high-pressure pipe 1, thereby forming the first flow paths 121 and 123 in the first section 25 and the third section 27. As a result, the path length of the high-pressure fuel F is extended compared to the distance when a straight line is drawn between the inlet (end 10a) and outlet (end 10b) of the high-pressure pipe 1 (the total length of the high-pressure pipe 1). That is, if the partition member 20 is not provided in the high-pressure pipe 1, the path length of the high-pressure fuel F will be approximately the total length of the high-pressure pipe 1, but by providing the partition member 20, the path length becomes the sum of the lengths of the first flow paths 121 and 123 and the second flow path 122, extending it by approximately three times.

[0028] Figure 5 is a graph showing a comparative example where the high-pressure pipe according to this embodiment is not applied to the fuel line between the common rail and the injector. Figure 6 is a graph showing the case where the high-pressure pipe according to this embodiment is applied to the fuel line between the common rail and the injector. Graphs 5 and 6(a) show the relationship between crank angle and injection signal, and graphs 5 and 6(b) show the relationship between crank angle and injection pressure.

[0029] In close-range weight reduction multi-stage injection, there is a requirement to shorten the total injection period. However, as shown in Figure 5, the pressure tends to decrease after the main injection, making it impossible to perform after-injection immediately. In contrast, as shown in Figure 6, when the high-pressure pipe according to this embodiment is applied, the path length of the high-pressure fuel F is extended, resulting in less pressure decrease after the main injection, making it possible to perform after-injection relatively quickly.

[0030] As described above, the high-pressure pipe 1 according to this embodiment is provided between the common rail B and the injector C and includes a passage 12 for circulating high-pressure fuel F. The passage 12 has a first passage 121 for circulating high-pressure fuel F in a first direction D1 and a second passage 122 for circulating high-pressure fuel F in a second direction D2 different from the first direction D1. As a result, in the high-pressure pipe 1, the path length of the high-pressure fuel F can be extended to a length that includes at least the first passage 121 and the second passage 122, compared to the distance of a straight line connecting the introduction and discharge points of the high-pressure fuel F.

[0031] According to the inventors' findings, by increasing the path length of the high-pressure fuel F, a phenomenon occurs where pressure pulsations are less likely to attenuate, making it possible to maintain high injection pressure after the main injection. Therefore, with the high-pressure pipe 1, the interval for pressure recovery after the main injection can be shortened, and the injection period of close-range reduction multi-stage injection can be shortened. Furthermore, as shown in Figure 7, by utilizing the phenomenon where the amplitude of pressure pulsations does not attenuate, it is possible to improve isovolume while taking advantage of the benefits of close-range reduction multi-stage injection, thereby achieving further improvement in thermal efficiency.

[0032] Furthermore, the high-pressure pipe 1 according to this embodiment includes a partition member 20 that divides the internal space 11, which forms the flow path 12, so that the internal space 11 includes a first portion 25 and a second portion 26 that is in communication with the first portion 25. The first flow path 121 is formed in the first portion 25, and the second flow path 122 is formed in the second portion 26. In this way, by dividing the internal space 11 of the high-pressure pipe 1 with the partition member 20, the first portion 25 and the second portion 26 that provide the first flow path 121 and the second flow path 122 are formed in the internal space 11. Therefore, it is possible to increase the path length of the high-pressure fuel F while suppressing an increase in the overall length of the high-pressure pipe 1.

[0033] Furthermore, in the high-pressure pipe 1 according to this embodiment, the high-pressure pipe 1 extends in a straight line, the first direction D1 is the direction from one extension direction De of the high-pressure pipe 1 to the other, and the second direction D2 is the direction from the other extension direction De to the one extension direction. The partition member 20 partitions the internal space 11 so that the internal space 11 includes a first portion 25 extending along the extension direction De, a second portion 26 extending along the extension direction De and communicating with the first portion 25, and a third portion 27 extending along the extension direction De and communicating with the second portion 26. First flow paths 121 and 123 are formed in the first portion 25 and the third portion 27. As a result, it is possible to increase the path length of the high-pressure fuel F while reliably suppressing an increase in the overall length of the high-pressure pipe 1.

[0034] The above embodiments illustrate one aspect of the present invention. Therefore, the present invention is not limited to the above embodiments and can be modified as needed.

[0035] For example, in the above embodiment, the case was described in which the internal space 11 of a straight high-pressure pipe 1 (pipe body 10) is divided into three parts (first part 25, second part 26, and third part 27) by a partition member 20 along its extending direction De. However, in the high-pressure pipe 1, the internal space 11 can be divided by the partition member 20 such that the internal space 11 includes at least the first part 25 and the second part 26. That is, the partition member 20 can divide the internal space 11 into two or more arbitrary parts.

[0036] Furthermore, the partition member 20 may divide the internal space 11 into multiple sections aligned along the extending direction De by a wall portion intersecting the extending direction De. Alternatively, without using the partition member 20, the flow path 12 may be configured by bending the high-pressure pipe 1 so that it includes at least a first flow path 121 and a second flow path 122, respectively, which circulate high-pressure fuel F in two distinct directions, a first direction D1 and a second direction D2. Moreover, the first direction D1 and the second direction D2 are not limited to being parallel and opposite directions, but may be intersecting directions. [Explanation of Symbols]

[0037] 1...High-pressure pipe, 11...Internal space, 12...Flow path, 20...Partition member, 25...First part, 26...Second part, 27...Third part, 121...First flow path, 122...Second flow path, 123...First flow path, A...Diesel engine (engine), B...Common rail, C...Injector, D1...First direction, D2...Second direction, De...Extending direction, F...High-pressure fuel.

Claims

1. A high-pressure pipe provided between the engine injector and the common rail for supplying high-pressure fuel from the common rail to the injector, The system includes a flow path for circulating the aforementioned high-pressure fuel, The flow path includes a first flow path for circulating the high-pressure fuel in a first direction, and a second flow path for circulating the high-pressure fuel in a second direction different from the first direction. High-pressure pipe.

2. The internal space forming the flow path includes a first portion and a second portion communicating with the first portion, and is provided with a partition member that divides the internal space. The first channel is formed in the first portion, and the second channel is formed in the second portion. The high-pressure pipe according to claim 1.

3. The high-pressure pipe in question extends in a straight line. The first direction is the direction from one of the extending directions of the high-pressure pipe to the other. The second direction is the direction from the other of the extending directions toward the one of the extending directions, The partition member partitions the internal space such that the internal space includes a first portion extending along the extending direction, a second portion extending along the extending direction and communicating with the first portion, and a third portion extending along the extending direction and communicating with the second portion. The first flow path is formed in the first and third portions. The high-pressure pipe according to claim 2.

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