JP4836191B2 - Manufacturing method of duct for vehicle - Google Patents

Description

  The present invention relates to a method of manufacturing a vehicle duct that is connected to, for example, an intake side of an engine mounted on an automobile and has a function of reducing intake noise generated when the outside air necessary for the engine is sucked. is there.

An engine mounted on an automobile or the like sucks external air necessary for rotational driving through an intake duct and an air cleaner connected to the intake side of the engine. Since intake noise is generated when external air is sucked from the intake duct, various techniques for reducing the intake noise have been proposed. For example, Patent Document 1 discloses a technique for reducing intake noise emitted from a small hole with the sound absorbing member by opening a large number of small holes in the intake duct and covering the small hole with a sound absorbing member made of fiber. ing.
JP 2000-282985 A

  In the configuration disclosed in Patent Document 1, since the sound absorbing member that covers the small hole has air permeability, warm air in the engine room is sucked into the intake duct through the sound absorbing member and the small hole, It causes engine output and torque performance to decrease. In addition, water that has entered the engine room may be sucked into the intake duct.

  Therefore, it is proposed that the opening formed in the intake duct is closed with a thin film having no air permeability, and the thin film is vibrated so that the intake sound is transmitted to the outside and reduced by the sound absorbing member. However, after the opening is formed in the intake duct, a process of attaching a thin film as a separate member is further required to close the opening, resulting in an increase in the number of parts and the number of processing steps, resulting in an increase in manufacturing cost. Further, if the attachment strength when the thin film is attached to the intake duct by welding or the like is insufficient, peeling may occur over time, and external air or water may be sucked from the gap.

  That is, the present invention has been proposed in view of the above-mentioned problems inherent in the above-described conventional technology, and has been proposed to suitably solve this problem, and is capable of preventing inhalation of unintended air or water. It is an object of the present invention to provide a method for manufacturing a vehicle duct capable of economically manufacturing a duct having a reduction function.

In order to solve the above-described problems and achieve an intended object, a method for manufacturing a vehicle duct according to the invention of claim 1 includes:
A method of manufacturing a duct for a vehicle,
A duct main body in which an air passage is defined; a bellows-like cylindrical portion that extends outward from the duct main body and communicates with the air passage; and a protruding end of the bellows-like cylindrical portion is closed to determine a thickness of the duct main body. A thin thin film part is integrally molded by blow molding,
The bellows-like tube portion is compressed and fixed to the duct body side.
According to the invention of claim 1, since the thin film portion is formed integrally with the duct main body, external air, water and the like are not sucked into the duct from the forming portion of the thin film portion. In addition, since the opening is not closed with a separate thin film, the number of parts and the number of processing steps are not increased, and the manufacturing cost can be kept low. Further, the thin film portion is not peeled off from the duct main body, so that no gap is generated, and suction of external air, water, or the like can be reliably prevented.

In the invention according to claim 2, the ratio of the opening width of the opening communicating with the air passage in the bellows-shaped cylindrical portion formed by blow molding to the protruding height of the thin film portion from the duct body is set to 1: 1 to The gist is that the range is 1: 2.
According to invention of Claim 2, the thin film part of appropriate thickness can be shape | molded, an intake sound can be permeate | transmitted favorably and durability can be ensured.

The gist of the invention according to claim 3 is that the vehicle duct is an intake duct connected to the engine.
According to the invention of claim 3, warm air, water or the like in the engine room is not sucked into the duct from the molding portion of the thin film portion, and it is possible to prevent engine output and torque performance from being lowered.

  According to the vehicle duct manufacturing method of the present invention, it is possible to prevent air and water from being sucked into the duct from the molded portion of the thin film portion having a function of reducing intake noise, and to reduce the number of parts and the number of processing steps. Thus, the manufacturing cost can be kept low.

  Next, a method for manufacturing a vehicle duct according to the present invention will be described below with reference to the accompanying drawings by way of preferred embodiments. In the embodiment, a description will be given of an intake duct that is connected to an intake side of an engine mounted on an automobile and serves to suck in air necessary for driving the engine as a vehicle duct. In the embodiment, in order to facilitate understanding, the intake duct for explaining the manufacturing process is illustrated in a simple cylindrical shape.

  The intake duct 10 (see FIG. 8) of the embodiment is based on a blow molding technique using the blow molding die 12 schematically shown in FIG. The projecting bellows-like cylinder part 16 and the thin film part 18 closing the projecting end of the bellows-like cylinder part 16 are integrally formed (see FIGS. 1, 3 and 5). That is, the blow molding die 12 includes the first molding die 20 having the first concave portion 20a recessed in the outer shape (lower half shape) of the duct main body 14, and the outer shape (upper half shape) of the duct main body 14 as well. The second molding die 22 having a second recess 24 that is recessed in the second recess 24 and a third recess 26 that is further recessed from the inner surface (molding surface) of the second recess 24 at a predetermined depth. The third concave portion 26 opens in a circular shape with respect to the inner surface of the second concave portion 24, and as shown in FIG. 2, a bellows-shaped surface in which peaks and valleys having a triangular cross section are continuous in the depth direction on the inner peripheral surface. 26a is formed. Further, the inner bottom surface of the third recess 26 that is separated from the second recess 24 is formed flat. The second mold 22 is composed of a pair of slide molds 22a and 22b that can be divided right and left from the center of the third recess 26, and the slide molds 22a and 22b are separated from each other left and right when the mold is opened. The bellows molding surface 26a is not limited to a triangular cross section, and may be a shape in which inward concave arcs and outward concave arcs are alternately connected.

  The first molding die 20 and the second molding die 22 are opened as shown in FIG. 1, and after setting the parison P molded from a synthetic resin material such as polypropylene (PP), for example, The mold 20 and the second mold 22 are closed. Next, by blowing compressed air into the parison P, the parison P expands and is pressed against the inner surface of the first recess 20a, the inner surface of the second recess 24, and the inner surface of the third recess 26, thereby forming an air passage 14a therein. Of the cylindrical duct body 14 that has been formed, the bellows-like cylindrical part 16 that protrudes outwardly from the duct body 14 into a bellows-like shape, and that communicates with the air passage 14a at one end. The thin film portion 18 that closes the protruding end (the other end) is integrally formed (see FIGS. 3 and 4). The material of the parison P is not limited to polypropylene, and various synthetic resins that can be blow-molded, such as polyethylene, can be used.

  In forming the bellows-like cylindrical portion 16 and the thin film portion 18, the portion facing the opening of the third recess 26 in the parison P was formed by expanding (stretching) and closely contacting the entire inner surface of the third recess 26. The thickness of the bellows-like cylindrical portion 16 and the thin film portion 18 is smaller than the thickness of the duct body 14. That is, the thin film portion 18 thinner than the thickness of the duct body 14 can be easily integrally formed by blow molding.

  Here, in blow molding, the thickness of the portion formed on the inner bottom surface when the material is expanded (stretched) and pressed onto the inner surface of the recess depends on the area of the opening in the recess and the area of the inner surface in the recess. Although it is defined, if the inside of the recess has the same diameter (width), it is simply defined by the opening width of the opening and the height from the opening to the inner bottom surface. The thickness of the thin film portion 18 may be a size that can vibrate due to the intake sound generated in the air passage 14a formed in the duct body 14, but the end portion of the bellows-like cylindrical portion 16 that communicates with the air passage 14a. The ratio of the opening width (inner diameter) L on the side and the projection height H of the thin film portion 18 from the duct body 14 is preferably set in a range of L: H = 1: 1 to 1: 2. (See FIG. 5). That is, if the protrusion height H is smaller than the opening width L, the thickness of the thin film portion 18 is large, and sufficient sound is not obtained and the sound reduction effect is small. On the other hand, if the protruding height H is larger than twice the opening width L, the thickness of the thin film portion 18 becomes too small, and there is a possibility that it will break during molding or a sufficient durability cannot be obtained. Accordingly, the opening width of the third recess 26 and the height to the inner bottom surface of the second mold 22 are set so that the opening width of the bellows-like cylindrical portion 16 and the protruding height of the thin film portion 18 have the above-described relationship. The As an example, when the thickness of the thin film portion 18 is 0.1 to 0.3 mm while the thickness of the duct main body 14 is 2.3 mm, a preferable effect of reducing the intake noise in the thin film portion 18 can be obtained. .

  By opening the first mold 20 so as to be spaced downward with respect to the second mold 22, and opening the pair of slide dies 22a and 22b in the second mold 22 so as to be spaced apart left and right, a duct is formed. A preform 28 in which the bellows-like cylindrical portion 16 and the thin film portion 18 are integrally formed on the main body 14 is obtained. As shown in FIG. 5, the bellows-like cylindrical portion 16 of the preform 28 is compressed from the inner and outer sides of the duct body 14 by a pair of heating press dies 30 and 32 (compressed in the extending direction with respect to the duct body 14). Crush the bellows and fix it to the duct body. As a result, as shown in FIG. 6, the intake duct 10 is obtained in which the thin film portion 18 faces the duct body 14 in the vicinity. In addition, a concave portion 30a having a size corresponding to the thin film portion 18 is formed on the pressing surface (the surface facing the thin film portion 18) of the heating press die 30 located on the thin film portion 18 side, and the bellows-shaped cylindrical portion 16 is compressed. In this case, the thin film portion 18 is not heated. The means for compressing and fixing the bellows-shaped tube portion 16 may be a cold press.

  In the intake duct 10 obtained by the manufacturing method of the embodiment, as shown in FIG. 7 or FIG. 8, a sound absorbing member 34 is disposed outside the duct body 14 corresponding to the thin film portion 18 so as to surround the thin film portion 18. And then put into practice. That is, when the thin film portion 18 is vibrated by the intake sound generated in the air passage 14a of the duct body 14, the intake sound is transmitted to the outside from the thin film portion 18, and the intake sound is absorbed by the sound absorbing member 34. Reduced. In addition, as the sound absorption member 34, what laminated | stacked the some nonwoven fabric is used suitably. Further, the vibration of the thin film portion 18 also has an effect of reducing the intake sound. In FIG. 8, the symbol AC indicates an air cleaner to which the intake duct 10 is connected.

  As described above, in the manufacturing method of the embodiment, the thin film portion 18 that transmits the intake sound generated in the air passage 14 a to the outside can be formed integrally with the duct body 14. It is possible to prevent engine air output and torque performance from being reduced due to warm air or water being sucked in. Moreover, since the duct body 14 and the thin film portion 18 are formed from a single member (parison P), the number of parts and the number of processing steps constituting the intake duct 10 do not increase, and can be manufactured at low cost. . Further, since the opening portion is not closed with a thin film of another member, the thin film portion 18 is not peeled off to form a gap, and suction of warm air or water in the engine room can be surely prevented.

  Furthermore, since the cylinder part which connects the thin film part 18 and the duct main body 14 was made into the bellows shape, when compressing the bellows-like cylinder part 16, it was crushed so that it might be folded neatly, and the bellows-like cylinder part 16 When the is crushed, a part of the wall does not protrude inward. That is, when the cylinder portion is crushed, a part of the tube portion protrudes inward and faces between the thin film portion 18 and the air passage 14a, thereby preventing the thin film portion 18 from affecting the permeation of intake sound. The Note that the space for installing the intake duct 10 in the engine room can be reduced by compressing the bellows-like cylindrical portion 16 and bringing the thin film portion 18 close to the duct body 14.

  In the embodiment, the case where the wall inner surface of the duct main body 14 is configured to be the start end of the bellows-shaped cylindrical portion 16 (see FIG. 5) is illustrated, but the start end in the bellows-shaped cylindrical portion 16 is illustrated as in the modification shown in FIG. Is located on the outer wall surface of the duct body 14 and is set so that the first wall extends in the direction of expanding from the starting end, and the subsequent transition width in the inner and outer directions of the peaks and valleys is set to the first wall. Set smaller than the displacement width in the inner and outer directions. As a result, the bellows-like cylindrical portion 16 is compressed on the outer surface of the duct main body 14, and the area of the thin film portion 18 with respect to the opening size at the communication portion between the duct main body 14 and the bellows-like cylindrical portion 16 as shown in FIG. , And good vibration in the thin film portion 18 can be achieved. In addition, in the modification shown in FIG. 9 and FIG. 10, the same code | symbol is attached | subjected and shown to the same part as an Example.

[Example of change]
The present application is not limited to the configurations of the above-described embodiments or modifications, and other configurations can be appropriately employed.
1. The shape of the bellows-like cylindrical portion and the thin film portion is not limited to a circle, and can be changed according to a duct formation site such as an ellipse or a rectangle.
2. In the embodiment, the intake duct connected to the engine has been described as an example of the vehicle duct. However, the vehicle duct may be an air-conditioning duct that is connected to an air conditioner and through which air-conditioning air flows.

  A method of manufacturing a vehicle duct according to the present invention is a method of integrally forming a thin film portion for reducing sound generated by air circulation in a duct body, and for a duct through which air requiring sound reduction flows. All can be suitably implemented.

It is process drawing which shows the manufacturing method of the air intake duct which concerns on an Example, Comprising: The state which set the parison to the blow mold which opened the mold is shown. It is principal part sectional drawing which shows the 3rd recessed part in the 2nd shaping | molding die of an Example. It is process drawing which shows the manufacturing method of the air intake duct which concerns on an Example, Comprising: The state which integrally molded the duct main body, the bellows-shaped cylinder part, and the thin film part by closing a blow molding die and blowing compressed air into a parison is shown. . It is principal part sectional drawing which shows the 3rd recessed part in the 2nd shaping | molding die of an Example in the state by which the duct main body, the bellows-shaped cylinder part, and the thin film part were integrally molded. It is process drawing which shows the manufacturing method of the air intake duct which concerns on an Example, Comprising: The state before compressing the bellows-shaped cylinder part in the duct body preformed is shown. It is principal part sectional drawing which shows the air intake duct manufactured by the manufacturing method of the Example. It is principal part sectional drawing in the case of actually using the air intake duct manufactured by the manufacturing method of an Example. It is a schematic perspective view which shows the state which installed the intake duct manufactured with the manufacturing method of the Example in the engine room. It is principal part sectional drawing which shows the preforming body by which the bellows-shaped cylinder part of the modification was shape | molded. It is principal part sectional drawing which shows the air intake duct obtained by compressing the bellows-shaped cylinder part of a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Intake duct, 14 Duct main body, 14a Air passage, 16 Bellows-shaped cylinder part 18 Thin film part, L Opening width of bellows-like cylinder part, H Projection height of thin film part

Claims (3)

A method of manufacturing a duct for a vehicle,
A duct main body in which an air passage is defined; a bellows-like cylindrical portion that extends outward from the duct main body and communicates with the air passage; and a protruding end of the bellows-like cylindrical portion is closed to determine a thickness of the duct main body. A thin thin film part is integrally molded by blow molding,
A method of manufacturing a vehicular duct, wherein the bellows-like tube portion is compressed and fixed to the duct body side.   Claims in which the ratio of the opening width of the opening communicating with the air passage in the bellows-shaped tube portion formed by blow molding to the protruding height of the thin film portion from the duct body is in the range of 1: 1 to 1: 2. Item 2. A method for manufacturing a vehicle duct according to Item 1.   The method for manufacturing a vehicle duct according to claim 1, wherein the vehicle duct is an intake duct connected to an engine.

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