JP2014196730A - Fuel supply pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To relax stress concentration on a local part of a supply hole 2c disposed for supplying a fuel from an internal passage 2a of a piping body 2 to injector attachment parts 3 in a fuel supply pipe 1 having the injector attachment parts 3 secured to several locations in the longitudinal direction of the piping body 2.SOLUTION: A supply hole 2c for supplying a fuel from an internal passage 2a of a piping body 2 to injector attachment parts 3 is disposed on a peripheral wall part 2b of the piping body 2. The supply hole 2c is a long hole that is long along a circumferential direction Y of the peripheral wall part 2b.

Description

  The present invention relates to a fuel supply pipe in which injector mounting portions are attached to several places in the longitudinal direction of one pipe body. Examples of the fuel supply pipe include a common rail provided in a common rail type fuel injection device for an automobile diesel engine.

  For example, a common rail (fuel supply pipe) used for a diesel engine mounted on an automobile or the like has a configuration in which injectors are attached at predetermined intervals in the longitudinal direction of one long accumulator vessel.

  For example, in the fuel delivery pipe shown in Patent Document 1, a separate cylindrical socket (injector mounting portion) is joined to one long communication pipe (piping body), and the longitudinal direction of the communication pipe is, for example, 2 Attachment pieces for fixing to an engine or the like are provided at some points.

  As the communication passage for supplying fuel from the internal passage of the communication pipe to each cylindrical socket, the cylindrical socket is formed in a through hole provided in the thickness direction of the peripheral wall portion (or thick portion) of the communication pipe. A cylindrical projection that is formed to protrude outward in the thickness direction is fitted and fixed to the bottom wall portion of the plate. This communication passage, that is, the inner hole of the cylindrical projection, is a circular hole.

Utility Model Registration No. 2514078 JP 2007-127096 A

  In the above Patent Document 1, the following problems are pointed out. For example, when the engine load is large (accelerator opening is large), the injector mounting of the piping main body depends on the reaction force of the fuel supply pressure from each of the injectors individually mounted on the injector mounting portions and the combustion pressure of the engine. There is a case that the vicinity of the part is bent like a bow in a form that is pushed toward the non-injector side.

  In such a case, compressive stress along the axial direction tends to concentrate on a portion of the projection of the cylindrical socket that intersects the central axis of the communication pipe, and the circumferential direction of the peripheral wall portion around the intersecting portion A tensile stress along the line will be generated. Therefore, when the bending is repeatedly generated, the projection of the cylindrical socket is likely to be deformed and damaged.

  By the way, although it does not correspond to the conventional example of this invention, Unexamined-Japanese-Patent No. 2007-127096 is mentioned as a reference example. In FIG. 5, FIG. 1 and paragraphs 0012-0017 of this prior art, “external connection portions into which injector connection pipe joints are screwed at several places in the longitudinal direction of one common rail are integrally projected radially outward. In the configuration in which the internal passage hole provided along the central axis (the radial direction of the common rail) of the plurality of external connection portions is connected to the internal passage hole provided along the central axis of the common rail. It is described that the cross section (cross section along the radial direction) of the entire length of the inner and outer communication holes is an elliptical shape.

  In the paragraphs 0002 and 0016 of this prior art, “in the case where external connection portions into which injector connection pipe joints are screwed at several places in the longitudinal direction of one common rail are provided so as to protrude radially outward. The stress concentration is caused by the pressure of the high-pressure fuel accumulated in the internal passage hole of the common rail at the intersection of the internal passage hole of the common rail and the internal and external communication holes of the external connection portion. Is reduced ”.

  That is, this prior art differs from the present invention in the premise of the invention that the common rail and the external connection portion are integrally provided, and the cause of the stress concentration is accumulated in the internal passage hole. The pressure of the high-pressure fuel is different from that of the present invention, and the cross-sectional shape (cross-section along the radial direction) of the inner and outer communication holes is elliptical over the entire length of the external connecting portion provided integrally with the common rail. Since the (long hole) is different from the present invention, this prior art is not a conventional example of the present invention but a reference example.

  In view of such circumstances, the present invention supplies fuel from the internal passage of the pipe body to the injector attachment parts in a fuel supply pipe in which injector attachment parts are attached at several locations in the longitudinal direction of one pipe body. The purpose is to alleviate the stress concentration at the local portion of the supply hole provided for this purpose.

  The present invention provides a fuel supply pipe in which injector attachment portions are attached to several locations in the longitudinal direction of a single pipe main body, and fuel is supplied from the internal passage of the pipe main body to each injector attachment portion on the peripheral wall portion of the pipe main body. A supply hole for supply is provided, and the supply hole is a long hole along the circumferential direction of the peripheral wall portion.

  In this configuration, the two long side portions of the supply hole made of the long hole are linear, or have a partial arc shape that is gentler than when the supply hole is a circular hole.

  Therefore, for example, when the engine load is large (when the accelerator opening is large), the reaction force of the fuel supply pressure from each of the injectors individually attached to the several injector attachment parts or the combustion pressure of the engine The vicinity of the injector mounting portion may be bent like a bow in such a form that it is pushed toward the non-injector side.

  In such a case, the compressive stress along the axial direction tends to concentrate on the two long side portions of the supply hole provided in the peripheral wall portion and intersects with the central axis of the internal passage. As a result, a tensile stress along the circumferential direction of the peripheral wall portion is generated. That is, the intersection part is a position where the maximum stress is generated by the stress concentration.

  Here, the degree of the maximum stress generated at the intersecting portion is smaller when the supply hole is a long hole along the circumferential direction of the peripheral wall portion than when the supply hole is a circular hole. . In other words, the stress concentration on the local portion of the supply hole is alleviated. Therefore, even if the bending occurs repeatedly, the possibility that a crack will occur at the intersecting portion is reduced. As a result, the pressure strength around the supply hole is improved as much as possible.

  Preferably, the injector mounting portion is separated from the pipe main body and joined to the pipe main body, and is provided with an introduction hole that receives the fuel in communication with the supply hole. A projecting portion that is engaged with the supply hole formed of the long hole is provided around the introduction hole.

  In this configuration, when the injector mounting portion is joined to the pipe main body, the mounting position of the injector mounting portion with respect to the pipe main body is positioned by engaging the protrusion into the supply hole including the long hole. It becomes possible.

  Preferably, the pipe body is formed in a cylindrical shape, the injector mounting portion is formed in a bottomed cylindrical shape, and a concave portion that is in contact with the outer periphery of the pipe body is provided in the bottom wall portion. The introduction hole may be provided in the recess.

  Here, the configuration different from the conventional example is clarified by specifying the shape and installation location of each component of the fuel supply pipe.

  The present invention provides a fuel supply pipe in which injector mounting portions are provided at several positions in the longitudinal direction of a single pipe main body, and a supply hole provided for supplying fuel from the internal passage of the pipe main body to each injector mounting portion. It becomes possible to alleviate the stress concentration on the local area. Therefore, according to the present invention, it is possible to improve the pressure strength around the supply hole, and to contribute to improving the reliability of the fuel supply pipe.

1 is a perspective view showing an overall appearance of an embodiment of a fuel supply pipe according to the present invention. It is a figure which expands and shows a part of the state which removed the injector attachment part from the piping main body of FIG. It is a figure which shows the state seen from the direction which exposes the long hole of a piping main body in FIG. FIG. 2 is a cross-sectional view showing a state in which a part of the fuel supply pipe in FIG. 1 is halved in the vertical direction along the longitudinal direction. It is a figure which shows the state which looked at the state which removed the injector attachment part from the piping main body of FIG. 4 from the side. FIG. 2 is a cross-sectional view showing a state in which a part of the fuel supply pipe in FIG. 1 is halved in the lateral direction along the longitudinal direction. It is a figure which shows typically a mode that fuel supply piping elastically deforms in the longitudinal direction in the sine curve shape in FIG. It is a figure which shows the image for demonstrating the stress which acts on the supply hole of the piping main body of FIG. FIG. 7 is a view corresponding to FIG. 6 in another embodiment of the fuel supply pipe according to the present invention. It is a comparative example of this invention, and is a figure corresponding to FIG. FIG. 11 is a diagram corresponding to FIG. 6 in the comparative example shown in FIG. 10. It is a figure which shows the image for demonstrating the stress which acts on the supply hole of the piping main body of FIG.

  BEST MODE FOR CARRYING OUT THE INVENTION Best modes for carrying out the present invention will be described in detail below with reference to the accompanying drawings.

  1 to 8 show an embodiment of the present invention. In the figure, 1 indicates the entire fuel supply pipe. In this embodiment, as a fuel supply pipe 1 of the present invention, a common rail provided in a common rail fuel injection device of an in-line four-cylinder diesel engine for automobiles is taken as an example.

  The fuel supply pipe 1 has a configuration in which an injector attachment portion 3 separate from the pipe body 2 is attached to several places (four places) in the longitudinal direction of one pipe body 2.

  The pipe body 2 is formed in a cylindrical shape, and is made of a material that has been subjected to a surface treatment (for example, nickel plating) excellent in corrosion resistance based on an iron-based metal such as steel, or stainless steel. .

  High-pressure fuel is supplied to the internal passage 2a of the pipe body 2 from a high-pressure fuel supply pump (not shown) provided in the fuel injection device and accumulated. Since the internal passage 2 a is a central hole of the pipe main body 2, the central axis X thereof is the central axis of the pipe main body 2.

  A supply hole 2c for opening the internal passage 2a to the outside is provided at a location corresponding to the attachment position of the injector attachment portion 3 in the peripheral wall portion 2b of the pipe body 2. The supply hole 2c is provided so as to penetrate in the thickness direction of the peripheral wall portion (or thick portion) 2b. Furthermore, attachment pieces (stays) 4 for fixing to an engine or the like (not shown) are provided at two locations in the longitudinal direction of the pipe body 2.

  An injector 5 (only one is shown in FIG. 1) is directly attached to each of the plurality of injector attachment portions 3 or indirectly through a pipe joint of a high-pressure pipe (not shown). It is attached. The injector mounting portions 3 are all the same, for example, have a bottomed cylindrical shape, and the material is the same as that of the pipe main body 2 described above.

  Moreover, the opening of the injector attachment part 3 is provided with a flange 3a extending outward in the radial direction. The bottom wall portion 3b of the injector mounting portion 3 is joined to the outer periphery of the pipe body 2 by, for example, appropriate welding.

  The bottom wall portion 3b of the injector mounting portion 3 is provided with a recess 3c that comes into contact with the outer periphery of the pipe body 2. Further, in the bottom wall portion 3b, an introduction hole 3d penetrating in the thickness direction of the bottom wall portion 3b is provided at the center of the recess 3c.

  When the injector mounting portion 3 is attached to the pipe body 2, the supply hole 2 c of the pipe body 2 and the introduction hole 3 d of the injector mounting portion 3 are brought into communication. That is, the supply hole 2 c and the introduction hole 3 d serve as a communication path for communicating the internal passage 2 a of the pipe body 2 and the injector mounting portion 3.

  In this embodiment, the supply hole 2c of the pipe body 2 is a long hole along the circumferential direction Y of the peripheral wall 2b. The shape of the long hole as the supply hole 2c is, for example, a substantially oval shape in plan view. The oval shape referred to here is defined as a shape that is substantially rectangular in plan view and whose both ends in the longitudinal direction are semicircular.

  On the other hand, the introduction hole 3d of the injector mounting portion 3 is, for example, a circular hole. For example, as shown in FIG. 6, when the diameter of the introduction hole 3d made of the circular hole is R, and the separation dimension (width dimension) of the two long sides in the supply hole 2c is W, the relationship R <W is set. Is done. However, a relationship of R = W is also possible.

  Further, in the recess 3c of the bottom wall portion 3b of the injector mounting portion 3, two protrusions 3e are provided around the introduction hole 3d so as to be engaged in the supply hole 2c formed of the long hole. The protrusion 3e has, for example, a cylindrical shape, and is provided at a position such that it contacts or is close to both ends in the longitudinal direction on the inner peripheral surface of the supply hole 2c formed of the long hole (opposite through a minute gap). ing.

  The shape, size and installation location of these two protrusions 3e can be easily positioned so that the introduction hole 3d is disposed in the supply hole 2c when the injector mounting part 3 is joined to the pipe body 2. It is preferable to consider. In order to do so, when the two protrusions 3e are engaged with the supply holes 2c made of the long holes, the injector mounting portion 3 is connected to the pipe body 2 in the circumferential direction Y of the pipe body 2. In addition, the shape, size, and installation location of the protrusion 3e may be specified so that the protrusion 3e does not move or slightly moves in the direction along the central axis X (longitudinal direction or axial direction).

  By the way, although not shown, a pressure sensor and a pressure safety valve are attached to both ends of the pipe body 2. The pressure sensor is a sensor that detects the fuel pressure in the pipe body 2, and a pressure signal is sent to a control system (ECU) of the fuel injection device. The pressure safety valve opens when the fuel pressure in the pipe body 2 exceeds the limit set pressure, and functions to keep the fuel pressure below the limit set pressure.

  As described above, in the embodiment to which the present invention is applied, since the supply hole 2c of the pipe body 2 is a long hole along the circumferential direction Y of the pipe body 2, the reaction force of the fuel supply pressure from the injector 5 It is possible to alleviate the stress concentration on the local portion of the supply hole 2c caused by the combustion pressure of the engine.

  Specifically, when the fuel supply pipe 1 configured as described above is attached to an engine (not shown) and the engine is operated, high-pressure fuel is supplied to and accumulated in the pipe body 2, and the high-pressure fuel is supplied from a plurality of injectors 5 The fuel is individually injected and supplied to a plurality of combustion chambers of the engine corresponding to the combustion order of the engine.

  The reaction force of the injection pressure and the combustion pressure of the engine at this time act on the injector mounting portion 3. For example, when the engine load is large (when the accelerator opening is large), as shown in FIG. May be elastically deformed in a substantially sine curve shape in a side view, and in such a case, stress acts on the supply hole 2c of the pipe body 2. The action image of this stress will be described in detail.

  For example, when the engine load is large (when the accelerator opening is large), the piping main body 2 is affected by the reaction force of the fuel supply pressure from each of the injectors 5 individually attached to the several injector attachment parts 3 and the combustion pressure of the engine. The vicinity of each injector mounting portion 3 may be bent like a bow in such a form that it is pushed toward the anti-injector 5 side.

  In such a case, as shown in FIG. 8, the compressive stress σx (white) along the central axis X is applied to the portions P1 and P2 intersecting the central axis X of the internal passage 2a at the two long sides of the supply hole 2c. (See arrows) tends to concentrate, and tensile stress σy (see thick arrow) along the circumferential direction Y of the peripheral wall 2b is generated around the intersections P1 and P2.

  That is, the intersections P1 and P2 are positions where the maximum stress is generated due to stress concentration. A compressive stress σx acts in the short axis direction of the supply hole 2c made of a long hole, and a tensile stress σy acts in the long axis direction of the supply hole 2c.

  Here, the degree of the maximum stress generated at the intersections P1 and P2 is, for example, as shown in FIGS. 10 to 12 when the supply hole 2c is a long hole along the circumferential direction Y of the peripheral wall 2b. It becomes smaller than the case of making a circular hole. That is, the stress concentration on the local portion of the supply hole 2c is alleviated. Therefore, even if the bending occurs repeatedly, there is a low possibility that cracks will occur at the intersecting portions P1 and P2. For this reason, the pressure strength around the supply hole 1c is improved as much as possible, and the fuel supply pipe 1 can be improved in reliability.

  10 to 12, when the supply hole 2c is a circular hole, the crack is likely to occur at the radially inner opening of the supply hole 2c, and the radially outer opening of the supply hole 2c is the injector. Since the rigidity is high due to the joining with the mounting portion 3, it hardly occurs.

  In addition, this invention is not limited only to the said embodiment, It can change suitably in the range equivalent to the claim and the said range.

  (1) In the above embodiment, an example in which an in-line four-cylinder engine is used as an application target of the present invention is described. However, the present invention is not limited to this example. It can be a type engine or a horizontally opposed engine.

  (2) In the above embodiment, an example in which the subject of application of the present invention is an automobile diesel engine is given. However, the present invention is not limited to this example. A gasoline engine or an engine other than a car can be used.

  (3) Although the example which made the piping main body 2 cylindrical shape is given in the said embodiment, this invention is not limited only to this, For example, it can also be set as a rectangular tube shape etc.

  (4) In the above embodiment, the case where the supply hole 2c made of a long hole has a substantially oval shape in plan view (a shape that is substantially rectangular in plan view and rounded in the longitudinal direction) is taken as an example. It is not limited only to this.

  For example, as shown in FIG. 9, the supply hole 2c can be substantially elliptical in plan view. In the case of this elliptical supply hole 2c, the two long side portions have a partial arc shape. The long side portion of the partial arc shape is gentler than when the supply hole 2c is a circular hole as shown in FIGS. In other words, the curvature of the long side part of the partial arc shape is larger than when the supply hole 2c is a circular hole.

  Therefore, in this case as well, the stress concentration on the local portion of the supply hole 2c caused by the reaction force of the fuel supply pressure from the injector 5 and the combustion pressure of the engine can be reduced, as in the above embodiment. As a result, the pressure-resistant strength around the supply hole 2c is improved as much as possible, so that the reliability of the fuel supply pipe 1 can be improved.

  The present invention can be suitably used for a fuel supply pipe in which injector mounting portions are attached at several places in the longitudinal direction of a single pipe main body.

1 Fuel supply piping
2 Piping body
2a Internal passage of piping body
2b Pipe wall peripheral wall
2c Supply hole in the peripheral wall
3 Injector mounting part
3b Bottom wall of injector mounting part
3c Concave part of bottom wall
3d Inlet hole in the bottom wall
3e Projection
4 mounting pieces
5 Injector

Claims (3)

A fuel supply pipe in which injector mounting portions are attached to several places in the longitudinal direction of one pipe body,
A supply hole for supplying fuel from the internal passage of the pipe main body to each injector mounting portion is provided in the peripheral wall portion of the pipe main body,
The fuel supply pipe is characterized in that the supply hole is an elongated hole along the circumferential direction of the peripheral wall portion. The fuel supply pipe according to claim 1,
The injector mounting portion is separate from the pipe body and joined to the pipe body, and is provided with an introduction hole that communicates with the supply hole and receives fuel.
A fuel supply pipe, characterized in that a projecting portion is provided around the introduction hole of the injector mounting portion. The fuel supply pipe according to claim 2,
The pipe body is formed in a cylindrical shape,
The injector mounting portion is formed in a bottomed cylindrical shape, and a concave portion that is in contact with the outer periphery of the pipe body is provided on the bottom wall portion thereof.
The fuel supply pipe, wherein the introduction hole is provided in the recess.

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