JP5208566B2 - Fuel injection rail - Google Patents

Description

  The present invention relates to a fuel injection rail used for an automobile engine, and more particularly, to a fuel injection rail that achieves both the absorption performance of fuel pressure fluctuations accompanying the opening and closing of an injector and the improvement of high pressure resistance.

  In a fuel supply system in an automobile engine, fuel in a fuel tank is sent to a fuel injection rail by a pump, and an appropriate amount of fuel is injected from an injector attached to the fuel injection rail to an intake manifold of the engine.

  In general, in fuel injection rails, fuel pulsations, vibrations, and abnormal noises generated by the opening and closing operations of the injectors are always a problem.

  Conventionally, in order to cope with pulsation and vibration, an external damper was used, or a damper means was built in the fuel injection rail, but recently, the three-dimensional shape of the fuel injection rail itself has been used. The technical trend is to try to absorb it. As this type of prior art, for example, one disclosed in Patent Document 1 can be cited.

The fuel injection rail proposed in Patent Document 1 has an L-shaped or T-shaped cross section of a tubular body constituting a main body portion in order to form a gas body reservoir acting as a cushion tank inside the main body of the fuel injection rail. It is a letter shape.
JP 2000-283000 A

  However, in order to add an absorption action such as vibration and abnormal noise to the main body of the fuel injection rail itself, it is advantageous that the fuel injection rail main body has a shape that easily deforms with pressure fluctuation and absorbs vibration and the like. However, when the strength of the fuel injection rail body is reduced and the expansion amount of the fuel injection rail body is increased, the burst strength tends to be relatively lowered. Moreover, since the main body is constantly exposed to plastic deformation due to repeated pressure fluctuations in the fuel injection rail main body, there is a risk of fatigue failure.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a fuel injection rail that solves the problems of the prior art and can improve both the performance of absorbing fuel pressure fluctuations and the resistance to high pressure. It is in.

In order to achieve the above object, the present invention provides a fuel delivery pipe having a main body portion in which a plurality of injector cups for attaching an injector are arranged in the length direction. Among the surfaces, the projected shape of the main body portion on the surface having the maximum displacement point that is the position where the amount of displacement due to pressure fluctuation accompanying opening and closing of the injector is maximized is a straight line having an outer diameter centered on the maximum displacement point Or, when the arc that touches the curve is C1, C2, C3,... From the smallest radius, and the radius of the inscribed circle is R1, R2, R3,.
R1≤R2≤R3≤3R1
It is characterized by satisfying the relationship .

  According to the present invention, since the stress concentration points can be dispersed, both the performance of absorbing fuel pressure fluctuations and the high-pressure strength can be improved.

Hereinafter, an embodiment of a fuel injection rail according to the present invention will be described with reference to the accompanying drawings.
First embodiment
FIG. 1 is a plan view showing a fuel injection rail according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view. In FIG. 1, reference numeral 10 indicates a main body portion of the fuel injection rail. Reference numeral 12 denotes a fuel supply pipe. Fuel in a fuel tank (not shown) is pumped through a fuel supply pipe 12 by a pump and introduced into a fuel injection rail.

  As shown in FIG. 1, the main body 10 of the fuel injection rail is an integral container having an upper surface and a lower surface that are relatively elongated pentagonal planar shapes. In the embodiment, an integrated type is cited, but a case having a pentagonal upper surface and a lower surface may be divided into two parts, and both may be overlapped and joined.

  The upper surface 14 of the main body portion 10 of the fuel injection rail is a flat surface and functions as a damping surface that absorbs fuel pressure fluctuations, as will be described later.

  On the other hand, injector cups 17 for attaching injectors (not shown) are attached to the lower surface 16 of the main body portion 10 of the fuel injection rail, arranged in the length direction at predetermined intervals. These injector cups 17 can be mounted by press-fitting an injector (not shown).

In FIG. 1, among the surfaces forming the main body portion 10 of the fuel injection rail, on the upper surface 14 that serves as a damping surface, the amount of displacement due to fuel pressure fluctuations associated with the opening and closing of the injector varies depending on the position. The amount of displacement is small as it goes to the periphery, but the position where the amount of displacement is the maximum is the maximum displacement point P. Then, an inscribed circle that touches each side around the upper surface 14 with the maximum displacement point P as the center is considered. In this case, in order from the smallest inscribed circle radius, the contact point of the inscribed circle C1 in contact with the side 19a is A1, the radius is R1, the contact point of the inscribed circle C2 in contact with the side 19b is A2, the radius is R2, and the side 19c The contact point of the inscribed circle C3 in contact is A3 and the radius is R3. Generalizing in this way, when the upper surface 14 is pentagonal, the three inscribed circles C1, C2, C3 have contact points A1, A2, A3, respectively,
R1≤R2≤R3
Will be.

  Looking at the relationship between the smallest inscribed circle C1 and the third largest inscribed circle C3, R3 cannot be too large in relation to R1, and has its own limits. R3 is at most twice less than R1, and the difference in radius between the inscribed circles C1, C2, and C3 is small. When commercialized, R3 is at most three times R1.

  On the other hand, the case where R3 becomes large is a case where the upper surface 14 of the fuel injection rail becomes an elongated rectangle as shown in FIG. In this embodiment, a rectangle as shown in FIG. 9 is excluded.

Therefore, the preferred range is
R1≤R2≤R3≤3R1 (1)
It is.

  Note that the case where the upper surface 14 is a perfect left-right symmetric pentagon and the maximum displacement point P is at the center of the pentagon is a special case where one inscribed circle C has the contacts A1, A2, A3. In this case, R1 = R2 = R3.

The fuel injection rail according to the present embodiment is configured as described above. Next, the operation and effect thereof will be described.
According to the fuel injection rail according to the present embodiment, the upper surface 14 of the main body 10 has inscribed circles C1, C2, C3 inscribed in the three sides with the maximum displacement point P as the center within the range satisfying the expression (1). Can do.

  This means that the volume fluctuation amount when the upper surface 14 of the main body portion 10 bulges or dents due to fuel pressure fluctuation is increased. In fact, when FIG. 1 is compared with FIG. 10, it is clear that even with the fuel injection rail of the same length, in the fuel injection rail of this embodiment, compared to the conventional fuel injection rail shown in FIG. The radii of the inscribed circles C1, C2, and C3 are substantially equal because the difference is reduced.

  In the fuel injection rail shown in FIG. 10, when the upper surface 30 is most swelled, stress concentrates at two points of the contact points A1 and A2 of the inscribed circles C1 and C2. On the other hand, in this embodiment, since the stress concentration points can be distributed to the three points of the contact points A1, A2, and A3 of the inscribed circles C1, C2, and C3, the same volume fluctuation amount can withstand higher pressure. It becomes like this.

  In this way, it is possible to achieve both improvement in performance for absorbing fuel pressure fluctuations and improvement in high-pressure strength.

Second embodiment
Next, a fuel injection rail according to a second embodiment of the present invention will be described with reference to FIGS.

  In the second embodiment, in the main body portion 10 of the fuel injection rail, the upper surface 20 has a substantially triangular planar shape (FIG. 3), and the upper surface 21 has a diamond-shaped planar shape (FIG. 4).

  According to the second embodiment described above, stress concentration points can be dispersed in the same manner as in the first embodiment, so that it is possible to achieve both improvement in performance for absorbing fuel pressure fluctuation and improvement in high-pressure strength. It becomes possible.

Third embodiment
Next, a fuel injection rail according to a third embodiment of the present invention will be described with reference to FIGS.

  In the third embodiment, the embodiment of FIG. 3 is modified to make the upper surface 22 elliptical (FIG. 5), and the embodiment of FIG. 4 is modified to make the upper surface 23 semi-elliptical (FIG. 6). Show.

  According to the second embodiment as described above, since the stress concentration portion becomes a line instead of a point, the stress can be dispersed, so that the performance of absorbing fuel pressure fluctuations can be improved and the high pressure versus strength can be improved. It becomes possible to achieve both.

Fourth embodiment
Next, with reference to FIG. 7, FIG. 8, the fuel injection rail by 4th Embodiment of this invention is demonstrated.

FIG. 7 is an example in which the embodiment of FIG. 1 is applied to a part of the upper surface 24 of the main body 10 of the fuel injection rail. FIG. 8 is an example in which the embodiment of FIG. 1 is applied to the side surface 25 of the main body 10 of the fuel injection rail.
According to the fourth embodiment, the same effect as that of the first embodiment can be obtained.

  The present invention has been described with reference to a preferred embodiment, but the present invention is a fuel injection rail having a main body portion having a planar shape as shown in the first to fourth embodiments. The cross-sectional shape of the main body is not limited to a specific shape. For example, the present invention can be applied to a fuel injection rail having a main body portion 10 having an L-shaped cross section as shown in FIG.

It is a top view which shows the fuel injection rail by 1st Embodiment of this invention. It is a side view which shows the fuel injection rail by 1st Embodiment of this invention. It is a top view which shows the fuel injection rail which has a substantially triangular planar shape by 2nd Embodiment of this invention. It is a top view which shows the fuel injection rail which has a rhombus planar shape by 2nd Embodiment of this invention. It is a top view which shows the fuel injection rail which has an elliptical planar shape by 3rd Embodiment of this invention. It is a top view which shows the fuel injection rail which has a semi-elliptical planar shape by 3rd Embodiment of this invention. It is a top view which shows the fuel injection rail by 4th Embodiment of this invention. It is a top view which shows the fuel injection rail of another example by 4th Embodiment of this invention. It is a front view which shows the L-shaped main-body part of the fuel injection rail which can apply this invention. It is a top view which shows the conventional fuel injection rail as a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Main part of fuel injection rail 12 Fuel supply pipe 14 Upper surface 16 Lower surface 17 Injector cup

Claims (6)

In a fuel delivery pipe having a main body portion in which a plurality of injector cups for attaching an injector are arranged in a length direction,
Of each surface forming the main body portion of the fuel delivery pipe, the projected shape of the main body portion on the surface having the maximum displacement point, which is the position where the displacement amount due to pressure fluctuation accompanying opening and closing of the injector is maximized,
Centering on the maximum displacement point, the arc that touches the straight line or curve forming the outer diameter is C1, C2, C3,... From the smallest radius, and the radius of the inscribed circle is R1, R2, R3,. sometimes,
R1≤R2≤R3≤3R1
A fuel injection rail characterized by satisfying the relationship . 2. The fuel injection rail according to claim 1 , wherein the surface having the maximum displacement point has a substantially pentagonal planar shape. The fuel injection rail according to claim 1 , wherein the surface having the maximum displacement point has a substantially rhombic planar shape. The fuel injection rail according to claim 1 , wherein the surface having the maximum displacement point has a substantially triangular planar shape. The fuel injection rail according to claim 1 , wherein the surface having the maximum displacement point has an elliptical planar shape. The fuel injection rail according to claim 1, wherein the surface having the maximum displacement point includes a part of the planar shape according to any one of claims 1 to 5 .

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