JPH0622524U - Engine exhaust manifold - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent interference between the bolt fastening holes of the flange and the flange or warpage of the flange due to thermal deformation of the exhaust manifold. [Structure] The head connecting flanges 5a to 5f of the exhaust manifold 1 are provided independently for each exhaust port.
Then, one of the bolt fastening holes 6 of the head connecting flanges 5a to 5f on the engine center side is used as a fixing hole for positioning, and the other is provided with predetermined crankshaft direction allowances La to Lf on the side far from the engine center side. As the elongated holes, the margins La to Lf are increased on the side farther from the engine center. The distance s between the flanges is set to be shorter than the minimum margin Lc of the bolt fastening hole 6.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an engine exhaust manifold.

[0002]

[Prior art]

 The exhaust system of a multi-cylinder engine uses an exhaust manifold including an independent passage that communicates with the exhaust port of each cylinder and a downstream collecting portion. Further, this exhaust manifold generally has a flange for head side connection corresponding to each exhaust port, and this flange is connected to the cylinder head by bolt fastening.

By the way, there is an exhaust manifold of this type in which a flange is provided independently for each exhaust port as shown in Japanese Utility Model Laid-Open No. 54-97623, and other Some have integral flanges for all exhaust ports.

[0004]

[Problems to be solved by the device]

 The exhaust manifold repeatedly expands and contracts due to temperature changes associated with engine operation and shutdown. At this time, in the case of an exhaust manifold in which a head connecting flange is provided independently for each exhaust port, each flange can be displaced in the crankshaft direction as the main body part such as the collecting part expands and contracts. Therefore, when the exhaust manifold contracts due to plastic deformation during expansion, the bolts interfere with the bolt fastening holes in the flange during contraction, which causes problems such as damage to the bolts and attachment / detachment of the exhaust manifold. Also, in the case of an exhaust manifold having an integral flange, the flange acts to restrain the main body part and suppress expansion, so that plastic deformation during thermal expansion increases and the amount of shrinkage of the main body part increases. As a result, the warpage of the flange becomes large, and gas leaks and head cracks easily occur.

The present invention has been made in view of the above problems, and prevents the bolt and the bolt fastening hole of the flange from interfering with each other and the flange from warping due to thermal deformation of the exhaust manifold. With the goal.

[0006]

[Means for Solving the Problems]

 In the present invention, since the head manifold flange of the exhaust manifold is integral with all exhaust ports, there is no problem of interference between the fastening bolt and the bolt hole, but repeated expansion and contraction due to heat Since it is not possible to prevent the warpage of the flange due to the contraction of the main body of the exhaust manifold in the process, it is premised that an independent flange is provided for each exhaust port. It is designed to prevent interference with holes by interference between the flanges, which is the same as in the case of the flange of a one-piece body. The structure is such that the connecting flanges corresponding to each exhaust port of the multi-cylinder engine are connected to the exhaust port. Independently for each, the distance between the flanges is the crank on the side far from the engine center of the bolt fastening hole of the flange. Characterized by being set to a shorter dimension than in the direction margin. Here, except for one of the flange bolt fastening holes, there is a margin in the crankshaft direction far from the engine center, except for one on the engine center, and that margin is far from the engine center. It is better to make the fastening hole larger.

[0007]

[Action]

 An exhaust manifold head connection flange is provided independently for each exhaust port, and the distance between the flanges is set to be shorter than the margin in the crankshaft direction on the side far from the engine center side of the bolt fastening hole. When the main body of the manifold contracts, the flanges are allowed to displace until they come into contact with each other, preventing the flanges from warping between them, so that the flanges warp. After hitting, the absolute amount becomes smaller. In addition, since each flange is not constrained to the extension side, the plastic deformation of the main body becomes small and the amount of shrinkage of the exhaust manifold itself becomes small. Further, after the flanges hit each other, the displacement of each flange is suppressed, so that the interference between the fastening bolt and the bolt hole is prevented. In addition, if the margin is set to be larger for the bolt fastening hole of the flange farther from the center of the engine, the flanges will always strike each other before the bolt and the bolt fastening hole interfere with each other, and the above effect will be remarkable. Become.

[0008]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view of an exhaust manifold according to an embodiment of the present invention, and FIG. 2 is a front view of a head connecting flange portion of the exhaust manifold. In the figure, reference numeral 1 denotes an exhaust manifold for a 6-cylinder engine, which has a pipe-shaped collecting portion 3 having an exhaust pipe connecting flange 2 at an opening at one end, and a short pipe branched from one side wall of the collecting portion 3. Each of the independent passage portions 4 is provided with head connecting flanges 5a to 5f independently of each other.

Each of the head connecting flanges 5 a to 5 f has a bolt fastening hole 6. One of the bolt fastening holes 6 on the engine center side is a fixing hole for positioning, and the other is a long hole having predetermined crankshaft direction allowances La to Lf on the side far from the engine center. These allowances La to Lf are such that the allowance allowance Lc of the other bolt fastening hole 6 of the flange 5c having the bolt fastening hole 6 for positioning is the minimum, and the bolt fastening holes 6 of the flanges 5b and 5d on both sides thereof are the same. The allowances Lb and Ld are slightly larger than that, and the margins La and Le of the outer flanges 5a and 5e of the bolt fastening holes 6 are slightly larger than the margins Lf and Ld of the outer flange 5f. Is set to be even larger. Specifically, for example, Lc is about 2 mm, Lb and L d are about 3 mm, La and Le are about 4 mm, and Lf is about 5 mm. The distance s between the flanges of the flanges 5a to 5f is set to be shorter than the minimum margin Lc of the bolt fastening hole 6, and is set to, for example, about 1 mm.

According to the above-described embodiment, when the collecting portion 3 expands due to heat during engine operation and tries to extend in the crankshaft direction, each of the flanges 5a to 5f can be independently displaced in the extending direction and has a small constraint. Therefore, the plastic deformation at the time of expansion is small, and therefore the amount of contraction of the exhaust manifold 1 in the process of repeating expansion and contraction is reduced. Further, during compression, the flanges are reduced in warp by allowing independent displacement of each of the flanges 5a to 5f until they come into contact with each other, and after the flanges come into contact with each other, further displacement of the flanges 5a to 5f occurs. Thus, the interference between the bolt fastening hole 6 and the bolt (shown by the one-dot chain line in FIG. 2) is prevented.

Although the above embodiment has been described with respect to the exhaust manifold of the 6-cylinder engine, the present invention can be applied to the exhaust manifold of other multi-cylinder engines in series or V type.

[0013]

[Effect of device]

 Since the present invention is configured as described above, it is possible to prevent the bolt fastening holes of the bolt and the flange from interfering with each other and the flange from warping due to thermal deformation of the exhaust manifold.

[Brief description of drawings]

FIG. 1 is a plan view of an exhaust manifold according to an embodiment of the present invention.

FIG. 2 is a front view of a head connecting flange portion of an exhaust manifold according to an embodiment of the present invention.

[Explanation of symbols]

1 Exhaust manifold 5a, 5b, 5c, 5d, 5e, 5f Head connecting flange 6 Bolt fastening hole

Claims (2)

[Scope of utility model registration request] 1. A coupling flange corresponding to each exhaust port of a multi-cylinder engine is provided independently for each exhaust port, and a distance between the flanges is a margin in a crankshaft direction on a side far from an engine center of a bolt fastening hole of the flange. Exhaust manifold for engines characterized by shorter dimensions than the generation. 2. The bolt fastening hole has a margin in the crankshaft direction far from the engine center except for one on the engine center side, and the margin is the bolt fastening hole of the flange far from the engine center side. Enlarged claim 1
Exhaust manifold for the listed engine.