JP2003120442A - Cooling structure for fuel pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling means for fuel return pipe eliminating need for an additional member or troublesome processing without causing a weight increase in a vehicle. SOLUTION: This cooling structure is integrally formed at an under cover for fuel piping. An air passage 50 is formed in the lengthwise direction along a fuel pipe arrangement section of the under cover 26, and a group 40 of protrusions formed by arranging a number of plateshaped or wen-shaped protrusions 42 at prescribed intervals are provided at a wall surface of the air passage 50. The group 40 of protrusions decreases the thickness of a boundary film by agitating inflow air into the air passage 50, thus increasing a cooling effect.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a cooling means for a fuel pipe in a vehicle. In particular, the invention is suitable as a cooling means for a fuel pipe of a common rail fuel injection system in a truck or the like.

Here, a description will be given by taking a cover of a fuel return pipe of a common rail type fuel injection system in a truck or the like as an example, but the present invention is not limited to this, and fuel for other vehicles such as passenger cars and diesel locomotives is used. The present invention can be applied to a pipe cover and the like.

[0003]

BACKGROUND ART FIG. 1 shows a schematic layout of a common rail fuel injection system to which the present invention is applied.

Between the fuel tank 12 and a plurality of injectors (injectors) 16 attached to the engine (gasoline engine or diesel engine) 14, fuel supply pipes (main piping) 18 of the plurality of injectors 16 are provided. It is distributed. A common rail (fuel distributor) 20 is provided immediately before the injector 16 of the fuel supply pipe 18, and a positive displacement fuel pump (supply pump) 22 that produces high-pressure fuel is provided immediately before the common rail 20. Further, between the injector 16 and the fuel tank 12, a fuel return pipe (return pipe) 24 for returning the unburned remaining fuel to the fuel tank 12 is arranged.

Here, the temperature of the return fuel in the common rail fuel injection system is 100 in summer and the like.
May exceed ℃.

This rise in the return fuel temperature is caused by the fuel tank 1
The internal pressure of 2 rises. This increase in the internal pressure of the fuel tank 12 not only affects the fuel injection stability and increases the fuel consumption, but also hinders the promotion of plasticization of the fuel tank. With plastic, even if a certain degree of heat resistance is obtained, it is practically impossible to secure a pressure resistance higher than a predetermined value in a high temperature atmosphere.

For this reason, conventionally, a fuel cooler made of aluminum is arranged in the middle of the fuel return pipe, and a radiation fin is directly formed on the fuel return pipe.

However, in the case of the above countermeasures, not only the weight of the vehicle is increased, but also the vehicle mountability is problematic due to the space of the lower surface (bottom surface) of the vehicle body.

Further, in the case of a fuel cooler, separate cooler piping is required together with the cooler main body, and in the case of a heat radiation fin, it is necessary to process the heat radiation fin on the pipe (which is troublesome), and a special member or troublesome processing is required. Was needed.

[0010]

DISCLOSURE OF THE INVENTION In view of the above, it is an object of the present invention to provide a cooling means for a fuel return pipe which does not increase the weight of a vehicle and does not require a special member or troublesome processing.

In order to solve the above-mentioned problems, the present inventors have paid attention to an undercover for fuel pipes (main / return pipes) that has been conventionally mounted on a vehicle in the process of earnestly developing. The present invention contemplates cooling means for fuel pipes, particularly for return pipes, of the present invention. A cooling structure integrally formed with an undercover for a fuel pipe, wherein an air passage is formed in a longitudinal direction along a fuel pipe disposition portion of the cover body, and the air passage is provided with a vertical vortex flow generating means. And

[0012] A concrete mode is a cooling structure integrally formed with an undercover for a fuel pipe, wherein an air passage is formed in a longitudinal direction along a fuel pipe disposition portion of a cover body, and a wall surface of the air passage. It is characterized in that it is provided with a projection group in which a large number of plate-shaped or bump-shaped projections are arranged at predetermined intervals.

As described above, by forming the vertical vortex flow generating means or the group of protrusions integrally with the undercover, the air flowing into the air passage of the undercover is disturbed by the vertical vortex flow generating means or the group of protrusions when the vehicle is running. Eddy current is generated. This swirl increases the air cooling effect on the fuel pipe. That is, the boundary film formed on the surface of the fuel pipe (a very thin layer in a laminar flow in contact with the boundary surface: a laminar bottom layer) becomes thin, the heat transfer coefficient becomes high, and the air cooling effect is increased. .

In the above structure, it is preferable that one or a plurality of air introduction ports be provided at an intermediate position in the longitudinal direction of the wall surface of the under cover along the fuel pipe installation site.
When the vehicle is traveling, uncooled air flows into the air passage even in the middle thereof, so that the air cooling effect is further enhanced. In particular, a large temperature difference occurs in the return pipe through which the excessively heated fuel after injection passes, and the air cooling effect becomes remarkable.

When the projection is plate-shaped, the angle of attack is preferably 20-80 ° and the projection height is preferably 0.2-0.8 times the gap between the projection and the fuel pipe. In these ranges, a swirling flow that thins the boundary film is likely to occur reliably, and the air cooling effect increases.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a plan view of the undercover before mounting on the vehicle body, and FIG. 3 is a plan view of FIG. 2 with fuel pipes and the like arranged.
FIG. 4 is an end view of the portion taken along the line 4-4 in FIG. 2 when the undercover is attached to the bottom wall of the vehicle body, and FIG.
It is an end view of the -5 line part. In addition, as a model, the undercover 26 is arranged at a shaded portion in FIG.

The undercover 26 of this embodiment has a dish-shaped cross section having upwardly curved portions (folded portions) 26a, 26a on both sides. Then, as shown in the figure, a main pipe (fuel supply pipe) 18 and a return pipe (fuel return pipe) 24, which are fuel pipes arranged in order from the vehicle inner side (back side), and a pair of brake pipes 28, 28 are provided. It is configured to protect from damage caused by flying stones. In addition to the above-mentioned pipe protection function, the under cover 26 also has a function of reducing air resistance when the vehicle is running by using a flash surface in the pipe portion at the bottom of the vehicle body.

The under cover 26 has a predetermined interval (for example, 50 to 150 mm) between the intrusion water discharge ports 31 such as muddy water.
And a plurality of clip locking hole pairs 34, 34 for attaching the undercover 26 to the vehicle body (usually 2 pairs).
Pair) on the tip side and the base side. A mounting bracket 38 having a mounting bolt hole 36 for a fuel tank flange portion (not shown) is provided outside the vehicle on the base side. Up to this point, the configuration is similar to that of the conventional undercover.

In the above structure, in this embodiment, the air passage 50 is provided along the fuel supply pipe (main pipe) 18 and the fuel return pipe (return pipe) 24 which are fuel pipes.
And the vortex flow generating means is provided in the air passage 50. Specifically, the return pipe 24 of the undercover 26
A protrusion group forming wall 41 provided with a protrusion group 40 for generating a vortex is vertically formed along the arrangement site of.

The projections (projection group elements) 42 constituting this projection group 40 are rectangular plate-shaped in the illustrated example, and are in a direction facing the air flow entering the cover, that is, in a diagonal direction toward the front of the vehicle. It is protruding.

The shape and size of the projection plate (projection portion) 42,
The arrangement form depends on the flow rate and flow velocity of the air passing through the air passage 50.

The angle of attack α of the protrusion 42 is 20 to 70 °,
Desirably, the angle is 30 to 60 °, and the inclination angle β is also the same.
Is usually 90 °, but can be arbitrarily selected in the range of 45 to 75 ° from the viewpoint of moldability and the like (see FIGS. 6 (a) and 6 (b)).

The protrusion height h of the protrusion 42 is set with respect to the general portion gap L between the protrusion group forming wall 27 and the return pipe 24.
It is 0.2 to 0.8 times, preferably 0.3 to 0.6 times (see FIG. 6 (c)). If the protrusion height h is too low or too high, the vertical vortex flow generation action is difficult to exert. Further, if it is too high, the air flow resistance increases, and the air cooling effect of the fuel return pipe also decreases.

The projection width w is 0.2 times or more the pipe diameter D and 0.8 times or less the height H of the air passage 50, preferably 0.4 times or more the pipe diameter and the air passage. It should be within 0.6 times the height of 50 (see FIG. 6).

Further, the pitch p of the protrusions 42 is 1.0 to 2.0 times, preferably about 1.5 times, the general portion gap L between the protrusion group forming wall 27 and the return pipe 24 (preferably about 1.5 times). See FIG. 6 (a).

The shape of the protrusion is rectangular in this embodiment, but it is trapezoidal, inverted trapezoidal, triangular, inverted triangular, and further,
Any shape may be used, such as a U-shaped plate cut into a shape similar to that of the fuel return pipe, as long as it causes air turbulence that can thin the boundary film.

In this embodiment, the projection plate (projection portion)
Although 42 is formed on the projection group forming wall 27 which is the side wall of the air passage 50, it may be formed on the bottom wall 26c together with the side wall or only on the bottom wall 26c.

Although not essential in this embodiment,
Return pipe (fuel pipe) 24 of the undercover
One or a plurality (three in the illustrated example) of air introduction ports 44 are formed in the bottom portion of the disposition portion at the intermediate position in the longitudinal direction. The air introduction port 44 has a rectangular shape in the illustrated example, and an opening-side semicircular introduction guide wall (duct wall) 46 is formed on the lower side.

As for the dimensional specifications of the air introducing port 44, for example, when the introducing port has a substantially square shape, the plane opening is about 10 mm, and the air introducing port 44 is provided at a pitch of 150 to 250 mm. The shape of the inlet 44 is not limited to a square, but a rectangle, a triangle,
A circle, an ellipse, a trapezoid, etc. are arbitrary. The directions of the triangle and the trapezoid may be reversed.

Although the air introduction port 44 is provided in the bottom wall of the under cover, it may be provided only in the side wall formed in the pipe disposition portion of the under cover or without being formed in the bottom wall and only in the side wall. In this case, it is desirable that no other member is arranged outside the side wall. Further, a protrusion (longitudinal vortex flow generating means) may be similarly provided on the main pipe side. In this case, a further increase in the cooling effect of the fuel can be expected.

The under cover is manufactured by injection molding using a fiber reinforced plastic material (for example, G-PP).

Next, a usage mode of the undercover having the above-mentioned structure will be described.

As shown in FIG. 5, an under cover holding clip 51 which also serves as a pipe holder is used in the present embodiment, and a pipe holder 54 having a locking claw portion 52 corresponding to each pipe, and the pipe holder. The configuration is provided with a tubular locking fitting portion 56 formed at the center position of the upper surface of the body portion 54, and bulging protruding portions 58 formed at symmetrical positions on both sides of the bottom surface of the pipe holding body portion 54. The holding clip 51 is made of a plastic material such as polyamide (PA) or polyacetal (POM) having heat resistance and spring elasticity by injection molding or the like.

In advance, a pair of fuel pipes 18 and 24, respectively
The brake pipes 28, 28 are piped in a pipe groove portion 60a formed in the vehicle body wall bottom wall 60. Further, on the lower surface of the vehicle body bottom wall 60, a furtley column 62 fitted to the locking fitting portion 56 of the holding clip 51 is projected so as to correspond to the locking fitting portion 56.

First, after attaching the holding clip 51 to the under cover 26 via the clip engaging hole pairs 34, 34, the under cover 26 is attached to the engaging fitting portion 56 of the retaining clip 51 on the furtley column 62. Make it fit. At this time, at the same time, the locking claws 52 are locked by the pipes 18, 24, 28.
To limit the swinging of the intermediate portion of each pipe when the vehicle is traveling.

When the vehicle travels in this state, high-temperature return fuel flows through the fuel return pipe 24. At this time, in the fuel return pipe 24, the air flowing from the air introduction port 44 is mainly disturbed by the projection group 40, and the boundary film is thinned.
For this reason, the fuel return pipe 24 is air-cooled and the temperature of the returned fuel also drops. Therefore, when returning to the fuel tank 12, the fuel tank 12 is cooled to a predetermined temperature (for example, 80 ° C.) or lower, and the fuel tank 12 can be made of plastic.

[Brief description of drawings]

FIG. 1 is a schematic layout diagram of a common rail fuel injection system to which the present invention is applied.

FIG. 2 is a plan view of an under cover before mounting on a vehicle body.

FIG. 3 is a partial view taken along the arrow 3 in FIG. 2 with a fuel pipe and the like arranged.

FIG. 4 is a view when the under cover is attached to the bottom wall of the vehicle body.
4-4 line end view

5 is an end view of the line 5-5 of FIG.

FIG. 6 is a model diagram for explaining a heat transfer tube flow path in which a rectangular protruding plate is formed.

[Explanation of symbols]

18 Main pipe (fuel supply pipe) 24 Return pipe (fuel return pipe) 26 Undercover 40 protrusions 42 Projections (projection group elements) 44 Air inlet 46 Air guide wall 50 air passage 60 vehicle bottom wall

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02M 37/00 B60K 15/02 C (72) Inventor Taku Ishikawa 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Vehicle Incorporated (72) Inventor Koji Miwa 1 Toyota-cho, Toyota-shi, Aichi F-term in Toyota Motor Corporation (reference) 3D003 AA08 BB01 CA13 DA07 3D038 CA09 CA37 CB01 CC17 CD12

Claims (6)

[Claims] 1. A cooling structure integrally formed with an undercover for a fuel pipe, wherein an air passage is formed in a longitudinal direction along a fuel pipe installation portion of a cover body, and a vertical vortex flow generating means is provided in the air passage. A cooling structure for a fuel pipe, comprising: 2. A cooling structure integrally formed with an undercover for a fuel pipe, wherein an air passage is formed in a longitudinal direction along a fuel pipe installation portion of a cover body, and a plate-like wall is formed on a wall surface of the air passage. Alternatively, a cooling structure for a fuel pipe, comprising a projection group in which a large number of bump-like projections are arranged at a predetermined interval. 3. The fuel according to claim 1, wherein one or more air introduction ports are provided at an intermediate position in the longitudinal direction of a wall surface of the undercover along the fuel pipe installation site. Cooling structure for pipes. 4. The cooling structure for a fuel pipe according to claim 1, 2 or 3, wherein the fuel pipe is a fuel return pipe. 5. The projection is plate-shaped and has an angle of attack of 20.
The cooling structure for a fuel pipe according to claim 1, 2 or 3, wherein the cooling structure has an angle of -80 °. 6. The fuel according to claim 1, 2 or 3, wherein the protrusion is plate-shaped and the protrusion height thereof is 0.2 to 0.8 times the gap between the protrusion and the fuel pipe. Cooling structure for pipes.