JP2012237298A - Common rail - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a common rail in which stress concentration at a branch section can be reduced, and which can be easily assembled.SOLUTION: The common rail includes a rail component 12 having a through hole 12a therein, a branch component 14, an outer tube 16 for accommodating the row of the rail component 12 and the branch component 14 which are arranged in series, and a pressing member 18 which is located at an end of the outer tube 16 to press the row of the rail component 12 and the branch component 14. The branch component 14 has an end wall face 12b of the rail component 12 adjacent thereto and end wall faces 14c, 14d facing an opening of the through hole 12a. Further, the branch component 14 has a plurality of branch holes 14a, 14b which are opened in one end wall face 14c, communicated with the through hole 12a, and separated from each other while their diameter being smaller than that of the through hole 12a. The end wall face 12b of the rail component 12 and the end wall faces 14c, 14d of the branch component 14 are pressed against each other by the pressing member 18, and sealed.

Description

  The present invention relates to a common rail, and more particularly, to a common rail that can reduce stress concentration at a branch portion and can be easily assembled.

  A conventional common rail has a cylindrical main pipe hole that extends in the longitudinal direction of the rail at the center, and branches perpendicularly to the longitudinal direction of the rail by cross-opening at several locations on the inner wall surface of the main pipe hole. A hole is formed. The intersection opening portion of the branch hole with respect to the main pipe hole has a problem that stress concentration occurs and becomes a starting point of fatigue failure. This is because the tensile stress generated around the main pipe hole and the tensile stress generated around the branch hole are combined to generate a tensile stress larger than that of other portions.

In order to solve such problems, in addition to using special materials with increased fatigue strength, various proposals have been made as follows.
(1) In the main pipe hole, the diameter of the branch hole is reduced, and the thickness near the branch hole is increased to reduce stress concentration (for example, Patent Documents 1 and 2).
(2) The stress concentration is reduced by offsetting the center of the branch hole with respect to the main pipe hole (for example, Patent Document 1).
(3) Stress concentration is reduced by making the vicinity of the intersection opening of the branch hole concave (for example, Patent Documents 3 and 4).
(4) The stress concentration is reduced by making the cross section of the main pipe hole and / or the branch hole elliptical (for example, Patent Document 5).

Japanese Patent No. 3778385 JP 2010-77846 A JP-A-8-232802 JP 2004-44448 A JP-A-10-169527

  However, the conventional proposed structure has a problem that processing is difficult or a stress concentration reduction with a practically significant difference cannot be obtained, and there is a limit to the reduction of the stress concentration.

  In order to solve such a problem, the present inventors have proposed a flow path branching structure capable of reducing the stress concentration in Japanese Patent Application No. 2010-263898.

  An object of the present invention is to further improve the common rail to which the flow path branching structure is applied.

In order to achieve the above object, the invention according to claim 1
A common rail having a main pipe hole,
A plurality of parts having a through hole constituting the main pipe hole;
An outer tube containing a row including the plurality of parts arranged in series;
A pressing member that presses a row including the plurality of components housed in the outer tube,
At least one part of the plurality of parts communicates with two end wall surfaces facing a part of the main pipe hole adjacent to the part, and with the main pipe hole part adjacent to the part opened to the same end wall surface. A plurality of branch holes formed separately from each other, and at least one of the plurality of branch holes is the through hole of the component,
The end wall surfaces of adjacent parts in a row including the plurality of parts are pressed to each other by the pressing member to secure a seal.

  According to a second aspect of the present invention, in the common rail according to the first aspect, at least one of the plurality of branch holes is formed in at least one end wall surface of the part having the branch hole and the part. It penetrates between the branch ports.

  According to a third aspect of the present invention, in the common rail according to the second aspect, the outer pipe is formed with a branch port that matches the branch port of the component.

  According to a fourth aspect of the present invention, in the common rail according to any one of the first to third aspects, a detent structure is provided between the outer tube and the at least one part. .

  According to a fifth aspect of the present invention, in the common rail according to any one of the first to fourth aspects, at least one of the plurality of parts does not have a plurality of branch holes, and constitutes a through hole that constitutes a main pipe hole. Only the rail part formed is characterized.

  The invention according to claim 6 is the common rail according to any one of claims 1 to 5, wherein the pressing member is screwed into an outer tube to press the row including the plurality of parts. To do.

  A seventh aspect of the present invention is the common rail according to the sixth aspect, wherein the pressing members are arranged on both sides of the row including the plurality of parts and screwed in directions approaching each other.

  The invention according to claim 8 is the common rail according to any one of claims 1 to 7, wherein the end wall surface where the plurality of branch holes open is flat at a portion facing the adjacent main pipe hole portion. It is a surface or a concave curved surface.

  According to the present invention, since the end wall surface of at least one part faces the portion of the main pipe hole adjacent to the part, the end wall surface receives a compressive stress from the internal fluid of the main pipe hole. Therefore, since the synthesis of the tensile stress as in the conventional case does not occur in the vicinity of the branch portion where the plurality of branch holes branch, the stress concentration can be sufficiently reduced as compared with the conventional case. In this way, an increase in the composite stress can be avoided, so that each component can be reduced in size and weight. Further, it is not necessary to use a material with a particularly high fatigue strength as the material of the part, and an inexpensive material can be used, so that the material cost can be reduced. In addition, parts can be easily processed.

  Furthermore, since the pressing component presses a row of a plurality of components housed in the outer cylinder and arranged in series, all the seals between the end wall surfaces of adjacent components can be secured at a time. As a result, the number of assembly steps can be reduced, and the assembly can be made very easy.

  A pressing force can be obtained by screwing the pressing member into the outer tube.

  The portion facing the portion of the main pipe hole adjacent to the end wall surface where the plurality of branch holes are opened is formed as a flat surface or a concave curved surface, thereby reliably receiving the compressive stress from the internal fluid of the main pipe hole. And the synthesis of tensile stress can be prevented.

It is sectional drawing of the common rail by embodiment of this invention. It is a longitudinal cross-sectional view of a rail component. It is a longitudinal cross-sectional view of a branch component. It is a longitudinal cross-sectional view of a branch component. It is a longitudinal cross-sectional view of a branch component. It is a longitudinal cross-sectional view of a branch component. It is a longitudinal cross-sectional view of a branch component. It is a longitudinal cross-sectional view of a branch component. It is a longitudinal cross-sectional view of a branch component. It is a longitudinal cross-sectional view of an outer tube. It is a longitudinal cross-sectional view of a pressing member. It is explanatory drawing sectional drawing of the stress which acts on the flow-path branch part of the common rail of this invention. It is explanatory sectional drawing showing the modification of the common rail of FIG. It is explanatory sectional drawing showing the modification of the common rail of FIG. It is explanatory sectional drawing showing the modification of the common rail of FIG. It is explanatory sectional drawing showing the modification of the common rail of FIG. It is explanatory sectional drawing showing the modification of the common rail of FIG. (A) is sectional drawing showing the connection structure of the branch port of the common rail of this invention, (b) is AA sectional drawing of (a).

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view of a common rail according to a first embodiment of the present invention.
In the figure, a common rail 10 includes a rail part 12 in which a through hole 12a in which an internal pressure from an internal fluid acts is formed, a branch part 14 adjacent to the rail part 12 and in which a plurality of branch holes 14a and 14b are formed, An outer tube 16 that accommodates a row of rail components 12 and branch components 14 arranged in series, and a pressing member 18 that is provided at an end of the outer tube 16 and presses the rows of rail components 12 and branch components 14. Composed. The material of these parts is preferably metal, but any material can be used as long as it has pressure resistance.

  An arbitrary number of rail parts 12 and an arbitrary number of branch parts 14 are alternately arranged in the rail axial direction, and one branch as a through hole 12a of each rail part 12 and a through hole of each branch part 14 The main pipe hole of the common rail is configured by communicating with the hole 14a. In FIG. 1, three rail parts 12 and four branch parts 14 are shown, but this is an example, and any number of rail parts 12 and branch parts 14 can be selected depending on the number of necessary ports. Can be used.

  As shown in FIG. 2, the rail component 12 basically has a cylindrical shape, and a through hole 12 a is formed along a central axis that coincides with the rail axis direction. Moreover, a part of end wall surface 12b of the both sides of the cylindrical rail component 12 is the taper surface 12c.

  As shown in FIG. 3A, the branch component 14 basically has a cylindrical shape (or may be a polygonal column shape), and a part of the first end wall surface 14c and the second end wall surface 14d at both ends thereof. Is a recess, and faces the end wall surface 12b and the through hole 12a of the adjacent rail component 12. The bottom surface of the recess is a flat surface perpendicular to the central axis that coincides with the rail axis direction, and the side surface of the recess is a tapered surface 14e that faces the tapered surface 12c of the end wall surface 12b of the rail component 12. It is like that. Further, a branch port 14 f is formed at an arbitrary position on the side peripheral surface of the branch component 14.

  At least one branch hole 14a of the branch component 14 is a through-hole penetrating the first end wall surface 14c and the second end wall surface 14d. On the other hand, another at least one branch hole 14b is formed to be inclined with respect to the central axis so as to penetrate the first end wall surface 14c and the branch port 14f. The branch hole 14a opens to the first end wall surface 14c and the second end wall surface 14d, and the branch hole 14b opens to the first end wall surface 14c and the branch port 14f. The branch holes 14a and 14b have smaller diameters than the through holes 12a, respectively, and are arranged so as not to intersect with each other.

  The configuration of the branch hole of the branch component 14 is not limited to that shown in FIG. For example, in the example shown in FIG. 3B, another branch hole 14b is formed so as to be inclined with respect to the central axis so as to pass through the second end wall surface 14d and the branch port 14f. It opens to the end wall surface 14d and the branch port 14f. The two branch holes 14b are three-dimensionally separated so as not to cross each other.

  In the example shown in FIG. 3C, two branch ports 14f are formed. One branch hole 14b passes through the first end wall surface 14c and one branch port 14f1 and opens to the first end wall surface 14c and the one branch port 14f1, whereas another branch hole 14b 14b passes through the second end wall surface 14d and another branch port 14f2, and opens to the second end wall surface 14d and the other branch port 14f2. The branch hole 14a and the two branch holes 14b are three-dimensionally separated so as not to cross each other.

  Further, in the example shown in FIG. 3D, in addition to the example of FIG. 3C, another branch hole 14b passes through the first end wall surface 14c and another branch port 14f2, and the first end wall surface 14c and the other branch are separated. The port 14f2 opens, and another branch hole 14b passes through the second end wall surface 14d and the one branch port 14f1, and opens to the second end wall surface 14d and the one branch port 14f1. The branch hole 14a and the four branch holes 14b are three-dimensionally separated so as not to cross each other.

  The above example is merely an example, and it is of course possible to provide three or more branch ports and three or more branch holes 14b so as not to cross three-dimensionally. One or two end wall surfaces 14c, Arbitrary branch holes can be formed between 14d and any number of branch ports.

  The branch component 14 ′ disposed at the end of the row of the rail component 12 and the branch component 14 may have the same configuration as the branch component 14 in the row, but is different from the branch component 14 in the row. It can also be. In the branch component 14 ′ disposed at the end of the row shown in FIG. 1, the recess of the first end wall surface 14 c has no tapered surface as shown in FIG. 3E. Further, although an O-ring 15 is mounted on the outer peripheral surface of the branching part 14 ', this O-ring 15 can be omitted. Or as shown to FIG. 3F and FIG. 3G, it can also be set as the structure without the branch hole 14a.

  As shown in FIG. 4, a branch port 16a is formed in the outer pipe 16 corresponding to the branch port 14f of the branch parts 14 and 14 ', and the row of the rail parts 12 and the branch parts 14 is arranged in the outer pipe 16. When properly positioned, the ports 14f, 16a are aligned. Further, female screw portions 16 b are formed at both ends of the inner peripheral surface of the outer tube 16. Further, in order to prevent rotation between the outer peripheral surface of the branch part 14 on the inner peripheral surface of the outer tube 16, a key and a key groove or a polygonal fitting, a groove and a positioning pin such as a positioning pin are provided. An element for this may be provided. In the anti-rotation structure of the illustrated example, a positioning hole 16c is formed at a location where the branch parts 14, 14 'of the outer tube 16 are to be disposed, and the positioning pin 17 fitted into the positioning hole 16c corresponds to the corresponding branch part 14. , 14 'is inserted into a shaft groove 14g (see FIG. 3A) to prevent rotation.

  As shown in FIG. 5, a male screw 18 a is formed on the outer peripheral surface of the pressing member 18 so as to be screwed into the female screw portion 16 b of the outer tube 16, and the pressing member 18 is attached to the outer end wall surface of the pressing member 18. A tool insertion hole 18b for inserting a working tool to be screwed into the tube 16 is formed. The shape of the tool insertion hole 18b is arbitrary, and an arbitrary torque applying structure can be provided instead of the tool insertion hole 18. Further, the inner end wall surface 18c of the inner end portion of the pressing member 18 is a flat surface, and a concave portion 18d is formed in the central portion of the inner end wall surface 18c.

  In order to assemble the common rail 10 configured as described above, the branch component 14 (or the branch component 14 ′) and the rail component 12 are sequentially inserted into the outer cylinder 16. Then, the pressing member 18 is screwed into the outer cylinder 16 so that the branch port 14f of the branching part 14 is aligned with the branching port 16a, and the two pressing members 18 are brought close to each other. By pressing the row from both sides, the end of the rail component 12 is inserted into the recesses of the end wall surfaces 14c, 14d of the adjacent branch component 14, and the end wall surfaces 14c, 14d are the openings of the through holes 12a of the rail component 12 and the rails. It faces the end wall surface 12b of the component 12. And the taper surface 14e of the end wall surfaces 14c and 14d and the taper surface 12c of the end wall surface 12b are brought into contact and abutted against each other, thereby establishing a seal and ensuring liquid tightness.

  Further, the inner end portion of the pressing member 18 is inserted into the concave portion of the end wall surface 14c of the branching part 14 ', and the end wall surface 14c faces the inner end wall surface 18c and the concave portion 18d of the pressing member 18. Then, the inner end wall surface 18c of the pressing member 18 comes into contact with and abuts against the end wall surface 14c of the branching part 14 ', so that a seal is established and liquid tightness is ensured.

  In the common rail 10 assembled as described above, the branch holes 14a and 14b of the branch parts 14 are communicated with the through holes 12a, and the branch holes 14a and the branch holes 14b are separated from each other. Branch off. The branch hole 14a as a through hole connects the through holes 12a of the rail components 12 adjacent to each other, and constitutes a main rail hole of the common rail together with the through holes 12a. An internal fluid is stored in the main pipe hole and a very high internal pressure is generated. The branch hole 14b is a branch path that branches from the main pipe hole of the common rail and communicates with the branch port 14f and the branch port 16a. Arbitrary piping can be connected to the branch port 14f and the branch port 16a.

  As shown in FIG. 6, since a part of the first end wall surface 14c faces the through hole 12a in the vicinity of the branch part of the branch part 14, the compressive stress σz acts from the internal fluid of the through hole 12a. . Therefore, in the vicinity of the branch portion of the branch part 14, the tensile stress σt is received by the respective hoop tensions of the branch holes 14 a and 14 b, but not the combination with the tensile stress of the hoop tension of the conventional main pipe hole but the combination with the compressive stress. It becomes. Therefore, the stress concentration can be sufficiently reduced as compared with the conventional case, and the occurrence of fatigue failure can be prevented.

  Furthermore, the rail component 12 and the branch component 14 mainly contact directly between the end wall surface 12b and the end wall surfaces 14c and 14d and are not directly joined to each other. The structure is also advantageous from the viewpoint of preventing transmission of tensile stress.

  Further, for the branch part 14 ′ arranged at the end of the row of the rail part 12 and the branch part 14, a part of the first end wall surface 14 c faces the recess 18 d of the pressing member 18. The pressure is applied in the same manner as when facing the component 12, and the stress concentration is similarly reduced. Thus, the recesses 18d of the respective pressing members 18 also constitute the main rail hole of the common rail, and the pressure is equally applied to the pressing members 18 on both sides.

  As described above, stress concentration can be avoided in the common rail according to the present invention, so that each component can be reduced in size and weight. Accordingly, workability is improved, and the temperature gradient can be made uniform during heat treatment during component manufacturing, particularly during cooling. Therefore, non-uniform material structure of the component can be prevented and quality can be improved. In addition, it is not necessary to use a material having a particularly high strength as the material of the part, and an inexpensive material can be used, so that the material cost can be reduced.

  In addition, since the parts are separated into the rail part 12 and the branch part 14, each processing is simplified.

  By the way, when the branch part 14 and the adjacent rail part 12 are individually connected to secure a seal between the end wall surfaces 12b and the end wall surfaces 14c and 14d, the connection work and connection are performed. Coupling parts are required, the number of man-hours and parts are increased, the advantages of weight reduction are impaired, and the presence of coupling parts increases the overall outer diameter and limits the degree of freedom in design. Occur.

  However, in the present invention, all the seals between the branch component 14 and the rail component 12 are once caused by pressing the entire row of the rail component 12 and the branch component 14 in the outer tube 16 by the pressing member 18. Therefore, the number of assembling steps can be reduced, and the assembling is very easy. In addition, since there is no need for coupling parts for individual connection, the structure is simple, the number of parts is small, the degree of design freedom is increased, the cost can be reduced and the weight can be reduced, and the coupling parts can be reduced. Therefore, the outer diameter can be prevented from becoming large.

  Furthermore, since the outer pipe 16 is provided, even if the seal between the branching part 14 and the adjacent rail part 12 is damaged or some parts are damaged, the outer pipe 16 can protect the outer pipe 16. Therefore, a structure that prevents the internal fluid from leaking directly to the outside can be easily achieved.

  In the above example, the pressing member 18 functions to press the row of the rail component 12 and the branch component 14 and also functions to close both ends of the main pipe hole of the common rail, so that the number of components is further reduced. Yes. Optionally, the pressing member 18 is a sensor that detects a measurement variable such as pressure, a valve such as a safety valve or a relief valve that is released when the pressure in the main pipe hole exceeds a predetermined pressure, or the main pipe hole through another flow path. It is also possible to use a member that also serves as a joint for communicating with the joint. Alternatively, a plug member 20 different from the pressing member 18 can be provided in order to close both ends of the main tube hole of the common rail (see FIGS. 9 and 10).

  Moreover, as shown in FIG. 7, the part of the 1st end wall surface 14c which faces the through-hole 12a of the rail component 12 of the branch component 14 can also be made into a concave curved surface instead of a flat surface. By making the concave curved surface, the workability becomes complicated compared to the example of FIG. 1, but the compressive stress near the branching portion of the branching part 14 acts reliably, so that stress concentration is the same as in the example of FIG. Can be effectively reduced.

  Alternatively, as shown in FIG. 8, the first end wall surface 14c and the second end wall surface 14d of the branch component 14 are provided with a convex portion 14g instead of the concave portion, and the end wall surface 12b of the rail component 12 is provided with a concave portion 12d. The convex part 14g may be inserted into 12d, or the concave part and the convex part may be omitted. Further, the tapered surfaces 12c and 14e may be omitted, and the flat surfaces of the first end wall surface 14c and the second end wall surface 14d of the branch component 14 may be abutted against the flat surface of the end wall surface 12b of the rail component 12.

  That is, the end wall surfaces 14c and 14d of the branch part 14 can be any combination of one or more of a flat surface, a concave curved surface, a tapered surface, a stepped surface (including a concave portion and a convex portion), a convex curved surface, and a spherical surface, The seal between the rail part and the branch part is not limited to the abutment between the flat surfaces and the tapered surface, but a seal by abutment with a spherical surface or a seal such as a copper alloy may be interposed.

  Further, instead of disposing the pressing member 18 on both sides of the outer tube 16, as shown in FIG. 9, one end of the outer tube 16 is closed and the pressing member 18 is provided only at the open end of the outer tube 16. It is possible to press the row of the rail component 12 and the branch component 14 with the pressing member 18 and the closed end of the outer tube 16.

  In the above example, the rail parts 12 and the branch parts 14 are alternately arranged to form a row. However, the present invention is not limited to this. Depending on the number and dimensions of the necessary branch ports, the branch parts 14 may be arranged continuously. In that case, the end wall surface of one branch part 14 and the end wall surface of the other branch part 14 may be arranged. It is advisable to ensure a seal between them. Furthermore, as shown in FIG. 11, it is possible to form a row with only the branch parts 14, or it is possible to include other parts other than the rail parts 12 and the branch parts 14.

  FIG. 12 shows an example of connection between the branch ports 14 f and 16 a of the common rail 10 and the branch pipe 34. In the connection structure of this example, an adapter 30 that contacts the periphery of the branch port 14 f and extends into the branch port 16 a is provided, and a connector 32 is provided on the outer periphery of the adapter 30. The connector 32 abuts on the inner peripheral surface around the branch port 16a of the outer tube 16 and extends to the outside through the branch port 16a. A male screw is formed on the outer peripheral surface of the extended portion. ing.

  On the other hand, the branch pipe 34 connected to the branch port is preferably a double pipe, and a coupling 36 is disposed on the outer peripheral side of the connection part 34a at the end. A male screw is formed on the outer peripheral surface of the connecting portion 34 a, and a collar 38 is screwed to the male screw, and an annular rib 36 a formed on the inner peripheral surface of the coupling 36 abuts the collar 38. Movement of the coupling 36 in the direction of the connection end is restricted. A female thread is formed on the inner peripheral surface of the coupling 36 on the connection end side.

  The connecting portion 34a having the collar 38 and the coupling 36 attached to the outer periphery is inserted into the connector 32, the coupling 36 is rotated, and the female screw of the coupling 36 and the male screw of the connector 32 are screwed together. Then, the connecting portion 34a moves into the branch port 16a, the connecting portion 34a communicates with the branch port 16a, and the end wall surface of the connecting portion 34a abuts against the end wall surface of the adapter 30 to ensure a seal. it can.

  An O-ring 40 is interposed between the connector 32 and the branch port 16a, between the coupling 36 and the connector 32, and between the coupling 36 and the outer tube 34 to secure a seal. Even if a liquid leak occurs in the branch pipe 34, the leak can be prevented from going outside.

DESCRIPTION OF SYMBOLS 10 Common rail 12 Rail components 12a Through-hole 12b End wall surface 12c Tapered surface 14 Branch component 14a Branch hole (through-hole)
14b Branch hole 14c End wall surface (first end wall surface)
14d end wall surface (second end wall surface)
14e Tapered surface 14f Branch port 14g Shaft groove (non-rotating structure)
16 Outer pipe 16a Branch port 16c Positioning hole (rotating structure)
17 Positioning pin (non-rotating structure)
18 Pressing member

Claims (8)

A common rail having a main pipe hole,
A plurality of parts having a through hole constituting the main pipe hole;
An outer tube containing a row including the plurality of parts arranged in series;
A pressing member that presses a row including the plurality of components housed in the outer tube,
At least one part of the plurality of parts communicates with two end wall surfaces facing a part of the main pipe hole adjacent to the part, and with the main pipe hole part adjacent to the part opened to the same end wall surface. A plurality of branch holes formed separately from each other, and at least one of the plurality of branch holes is the through hole of the component,
The common rail, wherein the end wall surfaces of the adjacent parts in the row including the plurality of parts are pressed together by the pressing member to secure a seal.   2. The at least one branch hole among the plurality of branch holes penetrates between at least one end wall surface of a part having the branch hole and a branch port formed in the part. Common rail described.   The common rail according to claim 2, wherein a branch port that matches the branch port of the component is formed in the outer pipe.   The common rail according to any one of claims 1 to 3, wherein a detent structure is provided between the outer tube and the branch part.   5. The rail part according to claim 1, wherein at least one of the plurality of parts is a rail part that does not have a plurality of branch holes and is formed only with a through hole constituting a main pipe hole. Common rail described in.   The common rail according to claim 1, wherein the pressing member is screwed into an outer tube to press the row including the plurality of parts.   The common rail according to claim 6, wherein the pressing members are respectively arranged on both sides of the row including the plurality of parts and screwed in directions approaching each other.   The end wall surface in which the plurality of branch holes are open has a flat surface or a concave curved surface at a portion facing the adjacent main pipe hole portion. Common rail described.