JP2011144768A - High pressure fuel delivery pipe for direct injection engine, and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent leakage of high-pressure fuel from a joint face between a mounting stay and a body pipe; and to enhance bond strength of the mounting stay, in a high-pressure fuel delivery pipe for direct injection engine. <P>SOLUTION: The mounting stay 20 of a fuel delivery pipe is constituted of: a tubular boss part 20a; a connection block part 20b formed integrally with the boss part; and a recess circular arc face 20c which is formed to a tip face 20d of the connection block part and can abut on an outer peripheral face of the body pipe 10 with no space therebetween. The recessed circular arc face of the mounting stay abuts on the outer peripheral face of the body pipe and is integrally stuck thereto. The mounting stay may be integrally stuck to the body pipe 10 by furnace brazing, after the recessed circular arc face is positioned to and abuts on the outer peripheral face of the body pipe and is temporarily fitting and fixed. A cylindrical hole 20cA in which the body pipe 10 is inserted may be formed to the connection block part of the mounting stay, instead of the recessed circular arc face, and the body pipe may be inserted into the cylindrical hole and is integrally stuck thereto. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a high-pressure fuel delivery pipe used in a direct injection engine that directly injects fuel into a combustion chamber of an engine and a method for manufacturing the same.

  As a conventional high pressure fuel delivery pipe for a direct injection engine of this type, there is a direct injection fuel rail assembly disclosed in Patent Document 1 (US Patent Application Publication No. US2009 / 0145504). The fuel distribution pipe of the direct injection fuel rail assembly has an elongated cylindrical conduit formed with a plurality of first and second arcuate concave portions, and each of the first and second arcuate surface shapes. The cylindrical injection valve socket and the outer peripheral surface of the mounting boss are brought into close contact with each of the recesses and fixed by brazing. Since the depths of the first and second arcuate planar recesses of the conduit are both greater than the thickness of the conduit, an opening communicating with the conduit is formed at the center of each arcuate recess. ing.

US Patent Application Publication No. US2009 / 0145504 (FIG. 1 to FIG. 4)

  In the technique of this patent document 1, as described above, since the opening communicating with the inside of the conduit is also formed in the central portion of the second arcuate concave portion for the mounting boss that does not require the passage of fuel, direct injection is performed. In the case of high-pressure fuel delivery pipes for engines, even if there is a slight defect in brazing, leakage of high-pressure fuel will occur from the brazed portion of the joint surface between the arcuate recess and the mounting boss. There is a problem that the manufacturing cost increases because it is necessary to strictly control the attached quality. Such a problem is caused by setting the depth of the second arc-shaped concave portion to which the outer peripheral surface of the mounting boss is closely attached and brazed to be smaller than the thickness of the conduit, so that the central portion of the second arc-shaped concave portion is In this case, it is possible to solve the problem by preventing an opening communicating with the inside of the conduit from being formed. However, by doing so, the joint area between the conduit and the mounting boss is reduced, and the joint strength of the brazed portion is reduced. Cause serious problems. The object of the present invention is to solve each of these problems.

  To this end, the high-pressure fuel delivery pipe for a direct injection engine according to the present invention includes a cylindrical main body pipe that is closed at both ends and supplied with pressurized fuel from a high-pressure fuel pump, and a control pipe connected to the main body pipe. A high pressure fuel delivery for a direct injection engine comprising a plurality of sockets to which fuel injection valves controlled to open and close by a unit are connected, and a plurality of mounting stays integrally fixed to the main body pipe for attaching the main body pipe to the engine In the pipe, the mounting stay includes a cylindrical boss portion, a connecting block portion that is integrally formed with the boss portion and protrudes from one side of the outer periphery thereof, and is formed on the front end surface of the connecting block portion. The mounting stay consists of a concave arc surface that can contact the outer peripheral surface of the pipe substantially without any gap. It is characterized in that the.

  In the high pressure fuel delivery pipe for a direct injection engine described in the preceding paragraph, a cylindrical hole through which the main body pipe can be inserted with a slight gap is formed in the connecting block portion of the mounting stay in place of the concave arc surface. May be integrally fixed by inserting the body pipe through the cylindrical hole.

  The method of manufacturing a high pressure fuel delivery pipe for a direct injection engine according to the present invention includes a cylindrical main body pipe that is closed at both ends and supplied with pressurized fuel from a high pressure fuel pump, and is connected to the main body pipe. High pressure fuel for a direct injection engine comprising a plurality of sockets to which fuel injection valves controlled to open and close by a control unit are connected, and a plurality of mounting stays integrally fixed to the main body pipe for mounting the main body pipe to the engine In the delivery pipe manufacturing method, the mounting stay includes a cylindrical boss portion, a connecting block portion that is integrally formed with the boss portion and protrudes from one side of the outer periphery thereof, and a tip surface of the connecting block portion. The mounting stay is formed of a concave arc surface that can be brought into contact with the outer peripheral surface of the main body pipe with substantially no gap. Because contacts after tacking fixed, is characterized in that integrally fixed to the body pipe by brazing in a furnace.

  In the manufacturing method of the high-pressure fuel delivery pipe for a direct injection engine described in the preceding paragraph, a cylindrical hole that can be inserted through the main body pipe with a slight gap is formed in the connecting block portion of the mounting stay instead of the concave arc surface, The mounting stay may be integrally fixed to the main body pipe by brazing in a furnace after the main body pipe is inserted into the cylindrical hole, positioned, and temporarily fixed.

  In the method for manufacturing a high-pressure fuel delivery pipe for a direct injection engine described in the preceding item 2, it is preferable that the temporary fixing is performed by TIG welding.

  According to the invention of the high pressure fuel delivery pipe for a direct injection engine according to claim 1, the mounting stay is formed integrally with the cylindrical boss portion and protrudes from one side of the outer periphery thereof. The connecting block portion is formed of a concave arc surface formed on the front end surface of the connecting block portion and capable of contacting the outer peripheral surface of the main body pipe with substantially no gap. The mounting stay has a concave arc surface on the outer periphery of the main body pipe. Since there is no need to perform any processing on the part where the mounting stay for the main pipe is attached, the fuel comes from the contact surface of the concave arc surface of the main pipe and the mounting stay. There is no risk of leakage. In addition, when forming a concave arc surface for attaching the mounting stay to the main pipe, it is necessary to increase the accuracy of the pitch between the concave arc surfaces, which increases the processing cost and causes distortion after brazing in the furnace. However, the straightness of the main pipe is lowered, but the invention of claim 1 which does not perform any processing on the main pipe does not cause such a problem. Furthermore, the concave arc surface of the mounting stay, which is the connecting surface with the main pipe, is formed integrally with the boss part and is formed in the connecting block part protruding from one side of the outer periphery, and the shape of the connecting block part is appropriate Since the surface area of the concave arc surface can be made sufficiently large by selecting this, the coupling strength between the main pipe and the mounting stay can be sufficiently increased without special quality control.

  A cylindrical hole that allows the main pipe to be inserted with a slight gap is formed in the connecting block portion of the mounting stay in place of the concave arc surface, and the mounting stay is integrated by inserting the main pipe into the cylindrical hole. According to the fixed invention of claim 2, as in the previous invention, since it is not necessary to perform any processing on the portion for attaching the mounting stay for the main body pipe, the contact between the concave circular arc surfaces of the main body pipe and the mounting stay. In addition to the possibility of fuel leakage from the contact surface, the area of the cylindrical hole of the mounting stay, which is the connection surface with the main pipe, is further increased, so that the coupling strength between the main pipe and the mounting stay is further increased. Can be increased.

  In the method for manufacturing a high-pressure fuel delivery pipe for a direct injection engine according to the present invention, the mounting stay includes a cylindrical boss portion, and a connecting block that is integrally formed with the boss portion and protrudes from one side of the outer periphery thereof. And a concave arc surface that is formed on the distal end surface of the connecting block portion and can substantially contact with the outer peripheral surface of the main body pipe without any gap. The mounting stay has the concave arc surface on the outer peripheral surface of the main body pipe. After positioning and abutting and fixing, it is firmly fixed to the main body pipe by brazing in the furnace, increasing the productivity when connecting the main body pipe and the mounting stay, so high pressure fuel delivery for direct injection engines The manufacturing cost of the pipe can be reduced.

  A cylindrical hole is formed in the connecting block portion of the mounting stay so that the main body pipe can be inserted with a slight gap in place of the concave arc surface, and the mounting stay is temporarily inserted by positioning the main body pipe through the cylindrical hole. According to the invention of claim 4, which is integrally fixed to the main body pipe by brazing in the furnace after being fixed, the productivity at the time of coupling the main body pipe and the mounting stay is increased, In addition to reducing the manufacturing cost of the high-pressure fuel delivery pipe for direct injection engines, the area of the cylindrical hole of the mounting stay, which is the connecting surface with the main pipe, is further increased. The bond strength between the two can be further increased.

  According to the invention of claim 5, in which the temporary fixing is performed by TIG welding, since it is not necessary to process the mounting stay on the mounting stay, the manufacturing cost of the mounting stay is reduced. Can do.

It is a lower side view showing the whole structure of one embodiment of the high pressure fuel delivery pipe for direct injection engines by the present invention. It is an expanded sectional view along line 2-2 of the embodiment shown in FIG. It is an expanded sectional view along line 3-3 of the embodiment shown in FIG. It is an expanded sectional view along line 4-4 of the embodiment shown in FIG. It is sectional drawing equivalent to FIG. 2 of the modification of embodiment shown in FIG.

  First, an embodiment of a high-pressure fuel delivery pipe for a direct injection engine according to the present invention will be described with reference to FIGS. As shown mainly in FIG. 1, the fuel delivery pipe FD of this embodiment includes an elongated main body pipe 10, a plug 11 and a joint member 12 that close one end and the other end thereof, and a predetermined space below the main body pipe 10. It is composed of three sockets 15 to be brazed and fixed, and mounting stays 20 that are brazed and fixed at four positions between one end of the body pipe 10 and each socket 15.

  One end of the body pipe 10 is sealed by inserting a bottomed cylindrical plug 11 and covering the other end with a joint member 12 and brazing. As shown in FIGS. 1 and 4, the joint member 12 is formed with a cylindrical portion 12 a protruding in the radial direction. A fuel supply pipe (not shown) is connected to the tip of the cylindrical portion 12a coaxially forming the fuel supply hole 12b by a union nut (not shown) screwed to the male screw 12c. The pressurized fuel from (omitted) is supplied into the main body pipe 10 through the fuel supply hole 12b. As shown in FIG. 1 and FIG. 3, a flat surface 10a is formed by pressing at three places as attachment portions of the socket 15 below the main body pipe 10, and a round hole 10b is formed at each center. Yes. The round holes 10b are used for positioning and connecting the socket 15. In this embodiment, the number of the holes and the pitch is three, but the number and the pitch are the number of cylinders arranged in series in the cylinder block to which the fuel delivery pipe FD is attached. And to match the pitch.

  As shown mainly in FIG. 3, the socket 15 is an integrally formed product including a bottomed cylindrical main body portion 15 a and a cylindrical portion 15 b having a smaller diameter than the main body portion 15 a protruding outward from the bottom surface. In this embodiment, the socket 15 has a cylindrical portion 15b inserted into the round hole 10b of the flat surface 10a from the lower side of the main body pipe 10, and the bottom surface of the main body portion 15a is brought into contact with the lower surface of the flat surface 10a. It is connected by brazing. The inside of the main body portion 15a of the socket 15 thus fixed is communicated with the inside of the main body pipe 10 through the inner hole of the cylindrical portion 15b.

  As shown in FIGS. 1 and 2, the mounting stay 20 includes a cylindrical boss portion 20a and a connecting block portion 20b that is formed integrally with the boss portion 20a and projects radially from one side of the outer periphery thereof. It consists of and. A semicircular arc-shaped concave arc surface 20c that can be brought into contact with the outer peripheral surface of the main body pipe 10 substantially without a gap is orthogonal to the axial direction of the boss portion 20a on the distal end surface 20d in the protruding direction of the connecting block portion 20b. It is formed in the direction. The front end surface 20d of the connecting block portion 20b in which the concave arc surface 20c is formed has a slightly larger vertical width in the axial direction of the boss portion 20a than the outer diameter of the main body pipe 10, and the lateral width is substantially equal to the diameter of the boss portion 20a. Is the same. The mounting stay 20 is brazed and fixed integrally with the concave arc surface 20c abutting against the outer peripheral surface of the main body pipe 10. The distance between the respective central axes is larger than the sum of the respective radii so that the boss portion 20a and the concave arc surface 20c do not penetrate each other. Although the number of the boss portions 20a is four in this embodiment, it is increased or decreased according to the number of sockets 15 or the like.

  The main body pipe 10 of this embodiment is obtained by cutting a stainless steel pipe, and the plug 11 and the socket 15 are press-formed products of a stainless steel plate. The joint member 12 and the mounting stay 20 are cast products of stainless steel by the lost wax method. The joint surfaces of the members 12 and 20 with the main body pipe 10, the upper and lower end surfaces of the boss portion 20a of the mounting stay 20, and the mounting bolts. The insertion hole 21 is cut.

  In the manufacture of the fuel delivery pipe FD, first, the concave arc surfaces 20c of the four mounting stays 20 are positioned and brought into contact with predetermined positions of the main body pipe 10, and a small number of TIG welding (tungsten inert gas arc welding) is performed. Temporarily fix by spotting. Then, the plug 11 is inserted into one end of the main body pipe 10, the joint member 12 is put on the other end, the main body pipe 10 is placed so that the flat surface 10a is on the upper side, and the cylindrical portions 15b of the three sockets 15 are connected to the flat surface 10a. And press-fitted into the center round hole 10b, and the bottom surface of the main body 15a is brought into contact with the flat surface 10a to be temporarily assembled, and placed at a necessary place. The members 10-12, 15, and 20 that have been temporarily assembled and placed in this manner are loaded into a brazing furnace in a posture in which each socket 15 is on the upper side, and heated to be brazed in the furnace. As a result, the members 10 to 12, 15 and 20 are brazed integrally in a liquid-tight manner, and the fuel delivery pipe FD is completed. The brazing material used is, for example, copper brazing. For the tacking by TIG welding, a welding rod may be used, or a part of the base material of the body pipe 10 and the mounting stay 20 may be melted and tacked without using a welding rod. .

  Temporary attachment of the mounting stay 20 to the body pipe 10 can be performed by projection welding instead of spotting by TIG welding. In that case, on the edge of the concave arc surface 20c of the mounting stay 20, It is necessary to form a projection welding projection that protrudes inward from the concave arc surface 20c. If necessary, the socket 15 and the like may be temporarily fixed to the main body pipe 10 by TIG welding or the like. Further, the placement may be performed in the vicinity of the outside of each contact surface after temporary assembly, or may be performed in a recess formed on a joint surface such as the concave arc surface 20c of the mounting stay 20 before temporary mounting. Good.

  In the high pressure fuel delivery pipe FD for a direct injection engine according to the above-described embodiment, the mounting stay 20 has the concave arc surface 20c abutting on the outer peripheral surface of the main body pipe 10 and is integrally brazed and fixed. Therefore, even if the fuel pressure in the main body pipe 10 is high, the pressure remains on the concave arcuate surface 20c of the main body pipe 10 and the mounting stay 20. Therefore, if there is any defect in the brazing part, there is no possibility of fuel leakage from such a defective part. In addition, when the concave arc surface for attaching the mounting stay to the main pipe is formed as in the prior art document described above, it is necessary to increase the accuracy of the pitch between the concave arc surfaces, which increases the machining cost. In addition, there is a problem that the straightness of the main body pipe is lowered due to strain after brazing in the furnace, but in the above-described embodiment, it is not necessary to perform processing on the main body pipe 10, so that such a problem does not occur. . Further, the concave arcuate surface 20c of the mounting stay 20 which is a brazing surface with the main body pipe 10 is formed integrally with the boss portion 20a and is formed in a connecting block portion 20b protruding from one side of the outer periphery thereof. By appropriately selecting the shape of the block portion 20b, the surface area of the concave arcuate surface 20c can be made sufficiently large, so that the coupling strength between the main body pipe 10 and the mounting stay 20 can be achieved without special quality control. Can be sufficiently increased.

  In the method for manufacturing the high-pressure fuel delivery pipe FD for a direct injection engine according to the above-described embodiment, the mounting stay 20 is temporarily fixed by TIG welding or the like by positioning and contacting the concave arc surface 20c with the outer peripheral surface of the main body pipe 10. Later, it is fixed integrally with the main body pipe 10 by brazing in the furnace, and the volume is reduced by the amount that the positioning fixing jig is unnecessary during brazing, and the number of fuel delivery pipes loaded into the brazing furnace. Since this increases the productivity during brazing, the manufacturing cost of the high-pressure fuel delivery pipe for a direct injection engine can be reduced.

  Further, in the embodiment described above, the temporary fixing is performed by TIG welding, and in this way, it is not necessary to process the mounting stay 20 such as a projection for temporary attachment. Can be reduced. Note that the same effect can be obtained even if tack fixing is performed by laser welding instead of TIG welding.

  Next, a modification of the fuel delivery pipe FD shown in FIG. 5 will be described. In this modification, since the connecting block portion 20bA of the mounting stay 20A is different from the connecting block portion 20b of the above-described embodiment, the difference will be mainly described. As shown in FIG. 5, the mounting stay 20 </ b> A of this modified example is formed integrally with the boss 20 a having the same shape as the above-described embodiment, and is formed integrally with the boss 20 a in the radial direction from one side of the outer periphery. The connecting block part 20bA protrudes. The connecting block portion 20bA has a vertical width slightly larger than the outer diameter of the main body pipe 10, a horizontal width substantially the same as the diameter of the boss portion 20a, and a cylindrical hole 20cA through which the main body pipe 10 can be inserted with a slight gap. Is formed in a direction orthogonal to the axial direction of the boss portion 20a. The distal end portion of the connecting block portion 20bA is formed in a semicircular arc shape concentric with the cylindrical hole 20cA. The mounting stay 20A of this modified example is also integrally brazed and fixed by inserting the main body pipe 10 through the cylindrical hole 20cA. The mounting stay 20A is a cast product of stainless steel by the lost wax method, like the mounting stay 20 of the above-described embodiment, and the cylindrical hole 20cA is cut.

  In the manufacture of the fuel delivery pipe of this modification, first, the main body pipe 10 is inserted into the cylindrical holes 20cA of the four mounting stays 20A, and the mounting stays 20A are positioned at predetermined positions with respect to the main body pipe 10 and TIG. Temporarily fix by a small number of points by welding. And, like the above-described embodiment, the plug 11, the joint member 12, and the socket 15 are temporarily assembled, placed in the necessary places, brazed, loaded into a brazing furnace, heated and brazed in the furnace, The members 10 to 12, 15 and 20A are integrally brazed in a liquid-tight manner to complete the fuel delivery pipe FD.

  In the high pressure fuel delivery pipe for a direct injection engine according to the above-described modification, the mounting stay 20A is brazed and fixed integrally with the cylindrical hole 20cA in contact with the outer peripheral surface of the main body pipe 10 as in the above-described embodiment. In addition, since it is not necessary to perform any processing on the portion of the main pipe 10 to which the mounting stay 20A is attached, there is no risk of fuel leakage from such a defective portion even if there is any defect in the brazed portion. There is no problem that the processing cost increases or the straightness of the main body pipe 10 decreases due to brazing in the furnace. Furthermore, since the area of the cylindrical hole 20cA of the mounting stay 20A that is the brazing surface with the main body pipe 10 is larger than that in the above-described embodiment, the coupling strength between the main body pipe 10 and the mounting stay 20A can be further increased. Can do.

  In the method for manufacturing a high-pressure fuel delivery pipe for a direct injection engine according to the above-described modification, the mounting stay 20A is temporarily inserted by positioning the cylindrical hole 20cA through the main body pipe 10 by TIG welding or the like, as in the above-described embodiment. After being fixed by brazing, it is fixed integrally with the main body pipe 10 by brazing in the furnace, which increases the productivity during brazing, thereby reducing the manufacturing cost of the high-pressure fuel delivery pipe for direct injection engines. Can do. Also, in the above-described embodiment, the temporary fixing is performed by TIG welding, and it is not necessary to process the mounting stay 20A such as a protrusion for temporary attachment, so that the processing cost can be reduced accordingly. it can.

DESCRIPTION OF SYMBOLS 10 ... Main body pipe, 15 ... Socket, 20, 20A ... Stay for attachment, 20a ... Boss part, 20b, 20bA ... Connection block part, 20c ... Concave circular arc surface, 20cA ... Cylindrical hole, 20d ... End face.

Claims (5)

A cylindrical main body pipe that is closed at both ends and supplied with pressurized fuel from a high-pressure fuel pump, and a plurality of sockets connected to the main body pipe and connected to a fuel injection valve that is controlled to be opened and closed by a control unit; In the high-pressure fuel delivery pipe for a direct injection engine comprising a plurality of mounting stays integrally fixed to the main body pipe for attaching the main body pipe to the engine,
The mounting stay includes a cylindrical boss portion, a connecting block portion that is integrally formed with the boss portion and protrudes from one side of the outer periphery thereof, and is formed on a front end surface of the connecting block portion. It consists of a concave arc surface that can contact with the outer peripheral surface of the
The high pressure fuel delivery pipe for a direct injection engine, wherein the mounting stay is integrally fixed by contacting the concave arc surface with the outer peripheral surface of the main body pipe. The high pressure fuel delivery pipe for a direct injection engine according to claim 1,
In the connecting block portion of the mounting stay, instead of the concave arc surface, a cylindrical hole is formed through which the main body pipe can be inserted with a slight gap,
The high pressure fuel delivery pipe for a direct injection engine, wherein the mounting stay is integrally fixed by inserting the main body pipe into the cylindrical hole. A cylindrical main body pipe that is closed at both ends and supplied with pressurized fuel from a high-pressure fuel pump, and a plurality of sockets connected to the main body pipe and connected to a fuel injection valve that is controlled to be opened and closed by a control unit; In the method of manufacturing a high-pressure fuel delivery pipe for a direct injection engine comprising a plurality of mounting stays integrally fixed to the main body pipe for attaching the main body pipe to the engine,
The mounting stay includes a cylindrical boss portion, a connecting block portion that is integrally formed with the boss portion and protrudes from one side of the outer periphery thereof, and is formed on a front end surface of the connecting block portion. It consists of a concave arc surface that can contact with the outer peripheral surface of the
The mounting stay is integrally fixed to the main body pipe by brazing in a furnace after the concave arc surface is positioned and abutted to the outer peripheral surface of the main body pipe and temporarily fixed. Of manufacturing high-pressure fuel delivery pipes for automobiles. In the manufacturing method of the high-pressure fuel delivery pipe for direct-injection engines according to claim 3,
In the connecting block portion of the mounting stay, instead of the concave arc surface, a cylindrical hole is formed through which the main body pipe can be inserted with a slight gap,
The mounting stay is fixed to the main body pipe by brazing in a furnace after the main body pipe is inserted and positioned in the cylindrical hole, positioned, and temporarily fixed, and then fixed to the main body pipe. Delivery pipe manufacturing method.   The method for manufacturing a high-pressure fuel delivery pipe for a direct injection engine according to claim 3 or 4, wherein the temporary fixing is performed by TIG welding.

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