JP6907391B2 - Gasoline direct injection rail - Google Patents

Description

The present invention relates to a rail for direct injection of gasoline.

Conventionally, as shown in Patent Document 1, a gasoline direct injection rail in which end caps are inserted and arranged at both ends of the rail body has been generally used, and among them, as shown in FIG. 4 , the rail body (31) has been used. In order to fix the end cap (32) so that it is difficult to detach, there is one in which the inner circumference (33) of the rail body (31) and the outer circumference (34) of the end cap (32) are brazed and fixed.

Japanese Unexamined Patent Publication No. 2012-97690

However, when the rail body (31) and the end cap (32) are brazed and fixed as described above, when an internal pressure is applied to the fuel flow section as shown by the arrow in FIG. Since (31) is deformed in the diameter-expanding direction, a force for peeling off the brazed portion (35) acts due to this deformation. Therefore, when the system is increased in pressure in the future, the brazed part (35) between the end cap (32) and the rail body (31) will be the brazed part (35) with the wall thickness of the conventional rail body (31). There is a risk of breaking from the tip (36) side of. As a means of avoiding such a situation, a method of making the wall thickness of the rail body (31) thicker than that of the conventional one can be considered, but when the wall thickness is thickened, the volume of the rail body (31) becomes large. As a result, heat cannot be easily transferred and the temperature cannot be raised to the melting temperature of the brazing material during brazing, which makes brazing difficult and increases the weight and reduces the fuel efficiency of gasoline. ..

Therefore, the present invention is intended to solve the above-mentioned problems, and even when the rail body and the end cap are brazed and fixed at the time of increasing the pressure in the gasoline direct injection system in the future, the rail body This is an attempt to prevent the brazed portion from being destroyed without increasing the wall thickness.

This onset Ming, together with the end cap is inserted in the opposite ends inwardly of the rail body, the inner and brazing fixed gasoline direct injection rail of the outer periphery and the rail body of the end cap, both ends of the rail body inward, its outer diameter with an end cap to correspond to the inner diameter of the rail body to insert disposed with a reinforcing ring on the outer periphery of the rail body, the position of the end cap side of the one end of the reinforcing ring, the The position overlaps the brazed portion between the rail body and the end cap, the distance Y from the tip of the brazed portion to the other end of the reinforcing ring is 5 mm ≤ Y ≤ 30 mm, and the wall thickness of the reinforcing ring is the rail. It is 40% or more of the wall thickness of the main body.

Here, a finite element analysis was performed on the stress reduction effect when the internal pressure of the rail body was applied when the rail body was provided with the reinforcing ring. Explaining this finite element analysis, first, a plurality of reinforcing rings are prepared in which the wall thickness of the reinforcing ring is 40% of the wall thickness of the rail body and the axial lengths L are 4, 5, 10 and 30, respectively. , The relationship between the stress ratio and the distance X from one end of the reinforcing ring to the tip of the brazed portion in each reinforcing ring was analyzed. The analysis result is shown in FIG. 3 (a) . The above stress ratio indicates the ratio of the generated stress when the rail body is not provided with the reinforcing ring and the generated stress when the reinforcing ring is provided, and the stress ratio = (when the reinforcing ring is provided). (Stress generated when the rail body is not provided with a reinforcing ring) / (Stress generated when the rail body is not provided with a reinforcing ring). When the stress ratio is 1.0, it means that there is no stress reduction effect, and the closer the value is to 0, the higher the stress reduction effect is.

As a result of this finite element analysis, as shown in FIG. 3A , when the length L = 4 of the reinforcing ring, the stress ratio does not decrease much from 1.0 regardless of the value of X, whereas L = 5 In the cases of 10 and 30, it was confirmed that the stress ratio clearly decreased from 1.0 as X approached 0. This result, in this onset bright and the distance Y from the tip of the brazed portion to the other end of the reinforcement ring as a Y ≧ 5 mm.

Next, prepare two types of reinforcing rings in which the axial length L is 10 mm and each wall thickness is 20% and 40% of the wall thickness of the rail body, and the stress ratio of each reinforcing ring and the reinforcing ring The relationship with the distance X from one end to the tip of the brazed portion was also analyzed. The analysis result is shown in FIG. 3 (b) .

From this finite element analysis result, as shown in FIG. 3 (b), when the wall thickness ratio with the rail body is 20%, the stress ratio hardly decreases, whereas when the wall thickness ratio is 40%, there is almost no decrease. It was confirmed that the stress ratio clearly decreased as X approached 0. This result, in this onset bright is not less than 40% of the thickness of the wall thickness rail body of the reinforcing ring.

Note that the present onset Ming, the position of one end of the end cap side of the reinforcing ring, since it is the essential element that is a position that overlaps the brazed portion between the rail body and the end cap, the reinforcement ring There is no particular problem with the distance from one end to the tip of the brazed portion.

In this onset bright, and the distance Y from the tip of the brazed portion to the other end of the reinforcement ring as a Y ≦ 30 mm. Even if the distance Y from the tip of the brazed portion to the other end of the reinforcing ring is longer than 30 mm, the effect of significantly reducing stress is not seen, and conversely, there is a problem that the material is wasted and the weight of the product becomes heavy. Occurs.

In this onset bright, the reinforcing ring is brazed, shrink fit, or may be one that is fixed to the rail body by welding.

This onset Ming application as described above, since those having a reinforcing ring on the peripheral position of the stress or displacement is large rail body, it is possible to suppress the deformation in the diameter direction of the rail body. Therefore, when the pressure is increased in the gasoline direct injection system in the future, even if the rail body and the end cap are brazed and fixed, it is not necessary to increase the wall thickness of the rail body, so that the weight of the rail body is increased. This makes it possible to prevent the brazed portion from being destroyed.

FIG. 5 is a cross-sectional view showing the first embodiment. The perspective view which shows Example 1. FIG. The graph which shows the relationship between the stress ratio and the distance X from one end of a reinforcing ring to the tip of a brazed part. Sectional drawing which shows the conventional example. A cross-sectional view of a conventional example when an internal pressure is applied.

For real Example 1 will be described below in FIGS. First, (1) is a rail body, and the outer diameter of the rail body (1) is 22 mm and the inner diameter is 17 mm. Further, the ratio of the outer diameter D of the rail body (1) to the wall thickness t is set to 0.1. The material of this rail body (1) is stainless steel. In this embodiment, the material of the rail body (1) is made of stainless steel as described above, but in other different embodiments, it may be made of steel. Further, a columnar end cap (2) whose outer diameter corresponds to the inner diameter of the rail body (1) is inserted and arranged inside both ends of the rail body (1).

Then, a brazing material (5) is placed at a distance between the outer circumference (3) of the end cap (2) and the inner circumference (4) of the rail body (1), and the end cap (2) and the rail body (1) are separated from each other. It is fixed with brazing. A reinforcing ring (6) is attached to the outer circumference (7) of the rail body (1). This reinforcing ring (6) has a cylindrical shape with an axial length L = 20 mm, and its inner circumference is fixed to the outer circumference (7) of the rail body (1) by brazing. Incidentally, as described above, in this embodiment, although brazed reinforcement ring (6) in the rail body (1) is not limited thereto in other different embodiments, rail body a reinforcing ring (6) It is also possible to place it fixedly in (1) by shrink-fitting or welding.

The wall thickness of this reinforcing ring (6) is 120% of the wall thickness t of the rail body (1). The material of the reinforcing ring (6) and the end cap (2) is stainless steel or steel. The dimensions of the rail body (1) used for the gasoline direct injection rail of the present invention are such that the outer diameter D is 10 mm to 25 mm, the inner diameter is 7 mm or more, and the ratio of the outer diameter D to the wall thickness t is t / D = 0. .1 to 0.25 is preferable.

In this embodiment also, the position location of the end cap (2) one side (10), which overlaps the attached portion curse the rail body (1) and end cap (2) (12) of the reinforcement ring (6) A reinforcing ring (6) is fixedly placed on the rail.

Its to the both ends in the side of the rail body (1), is inserted arranged corresponding to allowed the cylindrical end cap (2) the outer diameter to the inner diameter of the rail body (1), end cap (2) The distance between the outer circumference (3) of the rail and the inner circumference (4) of the rail body (1) is fixed by brazing with a brazing material (5). A reinforcing ring (6) is attached to the outer circumference (7) of the rail body (1), and the reinforcing ring (6) has a cylindrical shape with an axial length L = 30 mm. The inner circumference is fixed to the outer circumference (7) of the rail body (1) by brazing. The wall thickness of this reinforcing ring (6) is 120% of the wall thickness of the rail body (1).

Further , as shown in FIGS. 1 and 2, the position of one end (10) of the reinforcing ring (6) on the end cap (2) side is located at the brazed portion (12) between the rail body (1) and the end cap (2). The reinforcing ring (6) is attached to the rail body (1) so that it overlaps, and the end face on one end side of the rail body (1) is arranged so as to be flush with the end face on one end (10) side of the reinforcing ring (6). is doing. Then, the distance Y from the tip (13) of the brazed portion (12) between the rail body (1) and the end cap (2) shown in FIG. 1 to the other end (11) of the reinforcing ring (6) is set to Y =. It is set to 20 mm.

As described above, the position of one end (10) of the reinforcing ring (6) on the end cap (2) side overlaps with the brazed portion (12) between the rail body (1) and the end cap (2). (6) is fixedly arranged on the rail body (1), and the distance Y from the tip (13) of the brazed portion (12) to the other end (11) of the reinforcing ring (6) is Y ≧ 5 mm, and the reinforcing ring (6) is fixed. By setting the wall thickness of 6) to 40% or more of the wall thickness of the rail body (1), it is reinforced at the outer circumference (7) position of the rail body (1) where the amount of stress or displacement generated on the rail due to the application of internal pressure is large. It will be equipped with a ring (6). Therefore, deformation of the rail body (1) in the diameter-expanding direction can be suppressed, and destruction of the brazed portion (12) can be prevented.

1 Rail body
2 end cap
3 Outer circumference (end cap)
4 Inner circumference
6 Reinforcing ring
7 Outer circumference (rail body)
10 one end
11 The other end
12 Brazing part
13 tip

Claims (2)

In a gasoline direct injection rail in which end caps are inserted and arranged inside both ends of the rail body and the outer circumference of the end cap and the inner circumference of the rail body are brazed and fixed, the end caps are placed inside both ends of the rail body. with an outside diameter to be inserted placing end cap was corresponding to the inner diameter of the rail body comprises an outer reinforcing ring of the rail body, the position of the end cap side of the one end of the reinforcing ring, the rail body and the end cap The distance Y from the tip of the brazing part to the other end of the reinforcing ring is 5 mm ≤ Y ≤ 30 mm, and the wall thickness of the reinforcing ring is the thickness of the rail body. A gasoline direct injection rail characterized by being 40% or more. The gasoline direct injection rail according to claim 1, wherein the reinforcing ring is fixed to the rail body by brazing, shrink fitting, or welding.

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