JPH10110883A - Common rail - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a manufacturing cost and improve inner pressure fatigue strength, by connecting by an irregular fitting method, a plurality of short rail block units which has a flow pass inside its axial core and in which a boss having a through hole communicated with the flow pass, is projected on a peripheral surface preferably at right angle to the axial core, and brazing a connecting part. SOLUTION: A block unit 1-1 is a comparatively thick and small diametral metallic pipe, the inside of the axial core of the block unit 1-1 is made to serve as a flow pass 1-1', a boss 1-1a having a through hole 1-1a' communicated with the flow pass 1-1' by being off-centered from an axial core, is projected on an axial circumferential wall part at right angle to the axial core, and large diametral parts (recessed parts) 1-1" are arranged at both end parts of the flow pass 1-1'. The thusly composed block unit, for example, 1-1, 1-2 and 1-3 are connected to each other by irregular fitting by intervening a short cylindrical body 2 and so on if necessary, and the connecting parts thereof are brazed and welded 3 so as to be integrated, thereby a common rail 1 can be composed. Hereby, the block unit 1-1 can be formed short and the boss is required only one, so that a cost can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates generally to common rails such as high pressure fuel manifolds or block rails in diesel internal combustion engines.

[0002]

2. Description of the Related Art Conventionally, as a common rail of this type,
As shown in FIGS. 11 and 12, a flow passage 11 'is provided inside the shaft core.
A boss 12 having a through hole 12 'communicating with the flow passage 11' is provided at a predetermined interval on a peripheral wall portion of an integrated main pipe rail 11 having a branch pipe, and a branch branch pipe or a branch fitting is provided on the boss with a nut. Such a structure is generally used to connect a branch connector (not shown) as described above. In the case of such a common rail having an integral structure, the main rail 11 is manufactured by hot forging, and the passage 11 'of the main rail and the through hole 12' of the boss 12 are machined by a special drilling machine. ing. 13 is a bracket part.

[0003]

However, the conventional forged common rail has a disadvantage that the die cost is high. That is, the common rail changes the mounting position of the branch connection body depending on the type of the engine, and accordingly, the position of the boss also changes, and a forging die is required for each engine type, and this die cost is expensive. . Further, in the production by forging, when the production amount is small, the production efficiency is deteriorated, so that the cost is high. Further, there is a disadvantage that the cost of drilling by a dedicated machine is high.

Further, as shown in FIG. 11, the conventional common rail has a structure in which the center of the flow passage 11 'of the main pipe rail 11 and the center of the through hole 12' of the boss 12 coincide with each other. 11, when the internal pressure of a high-pressure fluid of 1000 kgf / cm ² or more, in which the supply pressure that is constantly repeated rapidly changes, acts on the internal pressure and the internal pressure acting on the through-hole 12 ′ of the boss 12. As a result, the largest stress is generated at the opening end P 'of the main rail flow passage 11', and the internal pressure fatigue strength is low.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks of the prior art. Instead of the conventional forged-type integrated common rail, a common rail having a divided structure constituted by brazing a plurality of blocks is provided. Along with
An object of the present invention is to provide a common rail capable of lowering a maximum stress value generated at an opening end of a main rail flow passage opening of a through hole of the boss by eccentricizing the boss and improving internal pressure fatigue strength. is there.

[0006]

In order to achieve the above object, the present invention provides a boss having a flow passage inside a shaft core and having a through hole communicating with the flow passage, and preferably has a boss formed on the outer peripheral surface thereof at a right angle to the shaft core. A common rail is characterized in that a plurality of short rail blocks protruding from the joint are joined by an uneven fitting method, and the joint is brazed. At least one short cylindrical body having a flow passage inside the shaft core may be interposed between the single bodies, or the boss may be eccentric in the radial direction of the flow passage so as to protrude from the outer peripheral surface, or the boss may be provided. In addition to being eccentric in the radial direction of the flow passage, it is inclined with respect to the axis of the rail block and protrudes from the outer peripheral surface.

[0007] With the above construction, the present invention requires only a short rail block (tie tube) and only one boss, so that the cost of the forging die is significantly reduced, and even small-volume production is possible. Because of the high production efficiency, the cost is not high, and the cost of drilling using special machines is also low. In addition, by interposing a short cylinder having a flow passage inside the shaft core between the rail blocks alone, the position of the boss can be arbitrarily changed according to the mounting position of the branch connection body. Can be easily handled. Further, by eccentricizing the center of the boss in the radial direction of the flow passage, the maximum stress value generated at the end of the through hole of the boss at the opening of the main rail flow passage is reduced, and the internal pressure fatigue strength is improved.

[0008]

FIG. 1 is a front view showing an example of a single block of a common rail according to the present invention, FIG. 2 is a longitudinal sectional side view taken along line AA of FIG. 1, and FIG. FIG. 4 is a front view showing an example of a single block with a bracket, FIG. 4 is a longitudinal side view taken along line AA of FIG. 3, FIG. 5 is a front view showing another example of another block of the common rail according to the present invention, and FIG. Similarly, a front view showing an example of a short tubular body (spacer) for adjusting the boss spacing interposed between the blocks of the common rail according to the present invention, and FIG. 7 shows an example of another block of the common rail according to the present invention. FIG. 8 is a longitudinal sectional side view taken along line AA of FIG. 7, FIG.
FIG. 10 is a front view showing an example of the entire configuration of the common rail according to the present invention. FIG. 10 is a partially enlarged sectional view showing another example of the present invention.
-1, 1-2, 1-3, 1-4 are block units, 1-1
Reference numerals a, 1-2a, 1-3a, and 1-4a denote bosses, 2 denotes a short tubular body, 3 denotes a brazed weld, and 4 denotes a blind plug fixed to an end of a main pipe rail.

A main rail 1 as a common rail is obtained by joining a plurality of blocks alone by a concave-convex fitting method and brazing the joined portions together to form a unit. 1-1, 1-2, 1-
4 and a block 1-3 having a convex portion, and if necessary, at least one short cylindrical body 2 is used so as to be interposed between the blocks.

The block unit 1-1 shown in FIGS.
For example, a relatively thick and small-diameter metal pipe having a pipe diameter of 26 m / m and a wall thickness of about 8 m / m, and a flow path 1-
1 ', a boss 1-1a having a through-hole 1-1a' eccentrically communicating with the axis and communicating with the axis at a right angle to the axis is formed on the peripheral wall in the axial direction. 'At both ends
The eccentricity Δl of the through hole 1-1a 'of the boss 1-1a is not particularly limited. No, but through hole 1
In order to reduce the stress generated at the opening end of the flow passage 1-1a ', as shown in FIG. 2, the tangent of the inner wall surface of the flow passage 1-1' and the tangent of the inner wall surface of the through hole 1-1a 'are almost equal. It is preferable to make them coincide. 1-1b is a screw part.

The block unit 1-2 shown in FIG. 3 and FIG.
The common rail mounting bracket 1-2 provided on the outer periphery
Except for c, similar to the block alone shown in FIGS.
The inside of the shaft core is formed as a flow passage 1-2 ′, and on the peripheral wall portion in the axial direction,
A boss 1-2a having a through-hole 1-2a 'eccentrically communicating with the shaft core is formed in the flow passage so as to project perpendicularly to the shaft core.
Large-diameter portion (recess) with an inner diameter of about 22 m / m at both ends of 2 '
The bracket 1-2c protrudes integrally with the outer peripheral wall of the block unit 1-2, and has a mounting hole 1-2c 'at the end. 2b is a screw part.

The block unit 1-3 shown in FIG. 5 is a large-diameter portion (recess) 1--1 of the block unit 1-1 or 1-2.
This is a block unit for joining to 1 "and 1-2" by a concave-convex fitting method. The inside of the shaft core is formed as a flow passage 1-3 'on the peripheral wall in the axial direction. A boss 1-3a having an eccentrically communicating through hole 1-3a 'is provided so as to project substantially at right angles to the axis, and a large diameter having an inner diameter of about 22 m / m, which is the same as that of the block alone, at one end of the flow passage 1-3'. A portion 1-3 "is provided, and the other end is provided with a convex portion 1-3d which is fitted to the large-diameter portions 1-1", 1-2 ", and 1-3". 1
-3b is a screw part.

The short cylindrical body 2 shown in FIG. 6 is a spacer for adjusting the boss interval, and has a flow passage 2 having an arbitrary diameter (same diameter in the illustrated example) with respect to the diameter of each block. 1
Is provided inside the shaft core, and each of the above-described blocks 1-
1, 1-2, 1-3 large diameter portions 1-1 ", 1-2", 1-
3 "has a convex portion 2-1 'fitted into the concave and convex portions.

The block unit 1-4 shown in FIG. 7 and FIG.
The boss 1-4 is inclined at an appropriate angle in the axial direction with respect to the axial center.
It has the same structure as 2. That is, the flow path 1-
A boss 1-4a having a through hole 1-4a 'eccentrically communicating with the axis of the flow passage at the peripheral wall portion in the axial direction as 4' and projecting at an angle .theta. Establish a flow passage 1
-4 'is provided with a large-diameter portion 1-4 "similar to the above at both ends. 1-4b is a screw portion. As described above, the boss is provided with an inclination. This is because the ease of installation and piping such as an injection pipe to the injection nozzle and a feed pipe from the high-pressure pump for each cylinder when the common rail is mounted on the engine is taken into consideration.

A common rail 1 shown in FIG. 9 is composed of the above-mentioned block units 1-1, 1-2, 1-3 and a short cylindrical body 2 as an example.
-2, 1-3 and the short cylindrical body 2 are respectively joined by being fitted into and recessed, and their joints are integrated by brazing 3. In the case of the common rail having such a structure, a place where a high stress is generated when an internal pressure is applied to each of the blocks 1-1, 1-2, and 1-3 is determined by the through holes 1-1a ', 1-2a', and 1-.
3a ', only the end P of the opening end of each flow passage, which is on the opposite side to the side where the inner wall surface of the flow passage and the inner wall surface of the through-hole substantially coincide, and the maximum generated stress is inevitably reduced. ,
The internal pressure fatigue strength of each block unit 1-1, 1-2, 1-3 is improved, and the durability of the common rail 1 itself is improved. Each boss may be provided with a flow limiter or the like as necessary.

On the other hand, in the above example, each block 1-
1, 1-2 and 1-3 are formed with concave portions at ends and convex portions at ends of a short cylindrical body 2 and are fitted by asperities and joined, and the joined portions are brazed and welded 3. As shown in FIG. 10, in the present invention, as shown in FIG. 10, a protrusion is formed at the end of the block unit 1-1, and a recess is formed at the end of the short cylindrical body 2. The part may be welded by brazing 3. In the example of FIG. 10, the diameter of the flow passage 1-1 ′ of the block unit 1-1 is smaller than the diameter of the flow passage 2-1 of the short cylindrical body 2. The thickness from the surface to the outer surface of the block unit is increased, and the internal pressure fatigue strength of the block unit is further improved. In this example, the blind plug 4 is fixed to the end of the main rail 1 by brazing or the like.

[0017]

As described above, the common rail according to the present invention requires only a short rail block (tie tube) and only one boss, so that the cost of the forging die is significantly reduced, and the production cost is small. Because of its high production efficiency, the cost is not high, and the cost of drilling with dedicated machines is also low. In addition, by interposing a short tubular body having a flow passage inside the shaft core between the rail blocks alone, the position of the boss can be arbitrarily determined according to the mounting position of the branch connector such as the branch pipe or the branch fitting. Because it can be changed, it can easily respond to changes in the engine model. Further, by eccentricizing the center of the boss in the radial direction of the flow passage, the maximum stress value generated at the end of the through hole of the boss at the opening of the main rail flow passage is reduced, and the internal pressure fatigue strength is improved. Therefore, the common rail according to the present invention has excellent effects of good quality and low cost as compared with the conventional forged type integrated common rail, and is extremely useful.

[Brief description of the drawings]

FIG. 1 is a front view showing an example of a single block of a common rail according to the present invention.

FIG. 2 is a longitudinal sectional side view taken along line AA of FIG. 1;

FIG. 3 is a front view showing an example of a single block with a bracket of a common rail according to the present invention.

FIG. 4 is a vertical sectional side view taken along line AA of FIG. 3;

FIG. 5 is a front view showing another example of a single block of the common rail according to the present invention.

FIG. 6 is a front view showing an example of a short tubular body (spacer) for adjusting a boss spacing interposed between the blocks of the common rail according to the present invention.

FIG. 7 is a front view showing an example of another block unit of the common rail according to the present invention.

FIG. 8 is a vertical sectional side view taken along line AA of FIG. 7;

FIG. 9 is a front view showing an example of the entire configuration of the common rail according to the present invention.

FIG. 10 is a partially enlarged sectional view showing another example of the present invention.

FIG. 11 is a front view showing an example of the entire configuration of a conventional common rail to which the present invention is applied.

FIG. 12 is an enlarged vertical sectional side view taken on line BB of FIG. 11;

[Explanation of symbols]

1 Main rail 1-1, 1-2, 1-3, 1-4 Block unit 1-1 ', 1-2', 1-3 ', 1-4' Flow passage 1-1 ", 1-2 ", 1-3", 1-4 "Large diameter portion 1-1a, 1-2a, 1-3a, 1-4a Boss 1-1a ', 1-2a', 1-3a ', 1-4a' Penetration Hole 1-1b, 1-2b, 1-3b, 1-4b Screw part 1-2c Bracket 1-3d Convex part 2 Short cylindrical body 2-1 'Convex part 3 Solder welding 4 Blind plug

Claims (4)

[Claims] 1. A plurality of short rail blocks each having a flow passage inside a shaft core and having a boss having a through hole communicating with the flow passage protruding from an outer peripheral surface are joined by an uneven fitting method, A common rail characterized in that said joint is brazed. 2. The common rail according to claim 1, wherein at least one short tubular body having a flow passage inside a shaft core is interposed between the rail blocks alone. 3. The common rail according to claim 1, wherein the boss is eccentric in a radial direction of the flow passage and protrudes from an outer peripheral surface. 4. The common rail according to claim 1, wherein the boss is provided on the outer peripheral surface so as to be inclined with respect to the axis of the rail block alone.