JP5896616B2 - Heat shield structure of exhaust path - Google Patents

Description

  The present invention relates to a heat shield structure for an exhaust path provided with a heat shield plate in order to reduce heat damage to peripheral parts such as an alternator.

  The heat damage that the parts of auxiliary machinery such as alternators deteriorate due to radiant heat from the engine and exhaust system during high-load operation becomes a problem.

  For this reason, conventionally, in order to reduce heat radiation to peripheral devices that are vulnerable to heat, a configuration in which the periphery of an exhaust pipe such as an exhaust manifold is covered with a heat shield has been adopted.

  FIG. 4 is a plan view of an exhaust manifold 102 having a conventional heat shielding structure for the exhaust path of the engine 101. The exhaust manifold 102 is formed with a mounting boss 102 a for mounting the heat shield cover 103. Thereby, the heat insulating cover 103 can be stably attached, and it is possible to prevent thermal damage of peripheral devices. Such a configuration is disclosed in Patent Document 1, for example.

  Another example of a structure for attaching a cover to the exhaust manifold is disclosed in Patent Document 2. This is shown in FIG. FIG. 5A shows the exhaust manifold 202, and FIG. 5B shows a cover 203 attached above the exhaust manifold 202. In the configuration shown in FIG. 5, mounting bosses 202a and 202b are provided on the upstream mounting flange 205 and the downstream mounting flange 204 of the exhaust manifold 202, respectively. A mounting boss 202 c is formed on the flat portion in the middle of the exhaust manifold 202. Thereby, it becomes possible to attach the cover 203 stably.

Japanese Utility Model Publication No. 63-166617 JP 7-224650 A

  However, in the configuration of Patent Document 1 shown in FIG. 4, the mounting boss 102a must be formed by casting, which increases the manufacturing cost.

  In addition, since almost the entire exhaust manifold 102 is covered with the heat shield cover 103, heat radiation to the peripheral equipment can be suppressed, but heat is easily generated in the heat shield cover 103, and thermal expansion of the exhaust manifold 102 is also caused. growing. For this reason, when the upstream side and the downstream side of the exhaust manifold 102 are firmly constrained, thermal stress is generated in the exhaust manifold 102, so that the pipe may be deformed or cracked. And when this exhaust manifold 102 is comprised by welding the half body shape | molded by press work, stress concentrates around a welding part and it is easy to produce a crack. However, if the wall of the tube is made thick so as to withstand this thermal stress, the vehicle weight increases, resulting in a reduction in fuel consumption.

On the other hand, in the configuration of Patent Document 2 shown in FIG. 5, the mounting boss 202c is provided at the intermediate portion (flat portion) of the exhaust manifold 202 and is reinforced, so that the thickness of the pipe is reduced in order to reduce the weight. It becomes possible to do. However, like the configuration of FIG. 4, the mounting boss 202c is
Must be formed by casting. In the configuration shown in FIG. 5, the mounting flanges 205 and 204 are also provided with mounting bosses 202a and 202b. The mounting boss provided at such a position is often attached by welding. However, both casting and welding increase the manufacturing cost.

  Therefore, in order to solve the above-described problems, the present invention provides a heat shield structure for the exhaust path with a low-cost configuration while suppressing deformation or damage due to thermal stress of the exhaust pipe between the cylinder head and the catalyst carrier housing portion. The purpose is to provide.

In order to achieve the above-described object, the heat shield structure for the exhaust path of the present invention connects the cylinder head of the engine whose exhaust system is configured on the front side of the vehicle and the catalyst carrier accommodating portion of the catalytic converter, and the halves are left and right A heat shield structure of an exhaust path provided with a heat shield plate along an exhaust pipe formed on an upper surface so that a welded portion extends in the front-rear direction of the vehicle, wherein the heat shield plate has one end Is attached to at least one of the exhaust pipe mounting seat of the cylinder head and the mounting flange of the exhaust pipe connected to the cylinder head, and the other end is attached to the catalyst carrier accommodating portion of the catalytic converter, and The intermediate region is unevenly arranged on the arrangement side of the peripheral device that requires heat insulation in the vehicle width direction, and the welding is performed in such a shape as to extend from the opposite side to the other end with respect to the arrangement side of the intermediate region. Part is the vehicle Characterized in that it is a notch formed so as to be exposed in a square side.

  As described above, according to the present invention, the heat of the catalyst carrier accommodating portion, which becomes high in temperature, is directed toward at least one of the cylinder head mounting seat and the exhaust pipe mounting flange at a lower temperature. Conducted through. Thereby, the excessive temperature rise of a catalytic converter is relieved.

  Moreover, the wind sent from the vehicle front side is introduced into the vehicle front side of the exhaust pipe from the notch formed in the intermediate region. As a result, an excessive temperature rise in the exhaust pipe connecting the cylinder head and the catalyst carrier accommodating portion can be mitigated, thereby reducing the influence of thermal stress generated in the exhaust pipe and preventing the occurrence of cracks and cracks. It becomes possible.

It is the perspective view which showed the heat insulation structure of the exhaust route which concerns on embodiment of this invention. It is a top view of the heat insulation structure of the exhaust path of FIG. It is a front view of the heat insulation structure of the exhaust path of FIG. It is the figure which showed the exhaust manifold which has the conventional heat insulation structure. It is the conventional exhaust structure, (a) shows an exhaust manifold, (b) is the figure which showed the cover which covers an exhaust manifold.

  Hereinafter, a heat shield structure for an exhaust passage according to an embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a perspective view showing a heat shield structure of an exhaust path from a cylinder head to a catalytic converter. Here, the illustration of the engine is omitted.

  Here, an exhaust path for an engine having an exhaust system provided on the front side of the vehicle is shown as an example. Further, auxiliary equipment such as an alternator arranged around a chain case (not shown) arranged on the left side of the drawing is simply expressed as a peripheral device 14.

  In the present embodiment, the exhaust manifold is configured inside the cylinder head, and the catalytic converter 4 is provided directly under the exhaust of the cylinder head.

  The catalytic converter 4 is connected to the engine by an exhaust pipe 6 (an exhaust pipe including a converter cone) extending from a mounting flange 10 to the cylinder head. A heat shield 8 is provided along the exhaust pipe 6.

  As can be seen from FIG. 1, the heat shield 8 is offset from the side where the peripheral device 14 is disposed. An upstream end portion 8a (one end) of the heat shield plate 8 is attached by a bolt 12 to a female screw hole formed in the mounting flange 10 by tapping or the like. Unlike the structure in which the female screw hole is formed in advance by tapping or the like in this way, a fastening structure using a tapping screw that does not require tapping may be used.

  Further, the downstream end portion 8 b (the other end) of the heat shield plate 8 is fastened to a bracket 16 provided on the side surface of the catalyst carrier accommodating portion 4 a of the catalytic converter 4. The intermediate region 8 c of the heat shield plate 8 is arranged at a constant interval along the exhaust pipe 6.

  Thus, in the heat shield structure for the exhaust path according to the present embodiment, a female screw hole formed in the mounting flange 10 is simply used without using a mounting boss that must be formed by casting or a bracket that requires welding. On the other hand, it is possible to attach the upstream end portion 8a of the heat shield plate 8 simply by fastening the bolt 12 to the heat shield plate 8. Therefore, processing becomes easy and an increase in manufacturing cost can be suppressed.

  Here, a notch 8d is formed on the downstream side of the intermediate region 8c of the heat shield plate 8. For the shape of the notch 8d and the shape on the opposite side of the peripheral device 14, FIG. 2 and FIG. It explains using.

  FIG. 2 is a plan view of the heat shield structure of the exhaust path of FIG. 1, and clearly shows that the heat shield plate 8 is unevenly provided only on the side where the peripheral device 14 is arranged. FIG. 3 is a front view of the heat shield structure of the exhaust path of FIG. 1, and the shape of the notch 8 d formed in the intermediate region 8 c of the heat shield plate 8 is clearly shown here.

  As can be seen from FIGS. 2 and 3, the heat shield 8 has a notch 8 d formed in the intermediate region 8 c on the downstream side and the vehicle front side. As a result, the exhaust pipe 6 can be directly exposed to the cooling air 18 such as the traveling air taken from the front side of the vehicle and the air flowing from the radiator fan. The notch 8d allows the cooling air 18 to enter between the exhaust pipe 6 and the heat shield plate 8, so that the exhaust pipe 6 is effectively cooled.

  In the case of such a configuration, the exhaust pipe 6 is restrained between the catalytic converter 4 and the mounting flange 10. That is, a large thermal stress is generated in the exhaust pipe 6 that is heated to a high temperature and whose thermal expansion is inhibited. Here, the exhaust pipe 6 formed by combining the half formed by press working with the welded portion 6a from the left and right is shown as an example, but when thermal stress occurs, stress is generated around the welded portion 6a. May concentrate and cause cracks.

  However, as described above, the heat shielding plate 8 is disposed only on the peripheral device 14 side where heat shielding is required, and a notch 8d into which the cooling air 18 can be introduced is formed on the vehicle front side. Therefore, excessive temperature rise can be suppressed and damage such as cracks and cracks can be prevented.

  As described above, when the heat shield plate 8 in the present embodiment is used, it acts to reduce the influence of the thermal stress of the exhaust pipe 6, and there is a margin in strength, so the thickness of the exhaust pipe 6 is reduced. Thus, it is possible to reduce the weight.

  In addition, the heat shield plate 8 is attached so as to bridge the catalyst carrier accommodating portion 4a and the attachment flange 10 of the catalytic converter 4 that becomes high temperature. Therefore, heat conduction occurs between the cylinder head 2 and the catalytic converter 4 via the heat shield plate 8.

  Here, reference is made to FIG. 2 showing the periphery of the mounting flange 10 in detail. During high temperature operation, the temperature of the mounting seat 2a side of the cylinder head 2 having a water jacket inside is lower than that of the catalytic converter 4. Therefore, the heat generated in the catalyst carrier accommodating portion 4a is diffused to the cylinder head 2 side via the heat shield plate 8, and the catalyst converter 4 can be prevented from being overheated.

  In the present embodiment, the thickness of the mounting seat 2a on the cylinder head 2 side and the thickness of the mounting flange 10 on the exhaust pipe 6 side is shown as an example, but the mounting flange 10 is formed thick. Then, since the heat capacity is increased, the heat of the catalytic converter 4 can be diffused more effectively.

  Further, in the present embodiment, an example in which the bolt is fastened to the mounting flange 10 has been shown, but the bolt may be fastened or tapped to the mounting seat 2a on the cylinder head 2 side.

  If comprised in this way, since the temperature is lower, the cylinder head 2 in which a water jacket is provided inside can obtain a higher heat sink effect. In addition, in this case, the joint of the mounting flange 10 can be reinforced by fastening or tapping the mounting seat 2a with the mounting flange 10 interposed therebetween.

  Furthermore, in the said embodiment, although the volt | bolt 12 showed the example fastened from the vehicle front side which is the same direction as the attachment direction of the attachment flange 10, the structure attached from other directions may be sufficient.

  For example, when the mounting flange 10 and the mounting seat 2a are formed thick so as to increase the heat capacity, the mounting can be performed from a direction perpendicular to the mounting direction. Even in such a configuration, it is possible to obtain the effect of a heat sink.

  Moreover, in the said embodiment, although the heat-shielding board 8 showed as an example the structure attached so that both ends might bridge between the cylinder head 2 and the catalyst carrier accommodating part 4a, along the exhaust pipe 6, it shows. The intermediate region 8c may be in contact with the exhaust pipe 6 as long as it is disposed.

  For example, when a part of the intermediate region 8c is arranged so as to be in pressure contact with the outer surface of the exhaust pipe 6, in addition to the heat shielding effect and the heat sink effect, an effect of suppressing the membrane vibration of the exhaust pipe 6 is also obtained. It is possible.

  Furthermore, in the above-described embodiment, an example in which the exhaust manifold is configured inside the cylinder head 2 has been shown, but the same applies to the case where the exhaust manifold is configured outside the cylinder head 2. That is, by disposing the heat shield plate 8 along the side surface of the exhaust manifold facing the side where the peripheral device 14 that is vulnerable to heat is disposed, it is possible to prevent the peripheral device 14 from being damaged by heat and to prevent the vehicle front side. Therefore, it is possible to apply the cooling air 18 such as the traveling air from the above, and similarly, it is possible to prevent the exhaust manifold from being distorted or cracked by the thermal stress.

  Moreover, in the said embodiment, although the heat shielding board 8 showed as an example the structure eccentrically provided by the side of the exhaust pipe 6, if it is the arrangement | positioning which can interrupt | block the radiant heat to the peripheral device 14, it will not be restricted to this. Absent. For example, when the peripheral device 14 is disposed below, the intermediate region 8c may be offset from the exhaust pipe 6 below.

1 Engine 2 Cylinder head 2a Mounting seat (exhaust pipe mounting seat)
4 Catalytic converter 4a Catalyst carrier housing 6 Exhaust pipe 8 Heat shield 8a Upstream end (one end)
8b downstream end (other end)
8c Intermediate area 8d Notch 10 Mounting flange 14 Peripheral device

Claims (1)

Connects the cylinder head of the engine that constitutes the exhaust system on the front side of the vehicle and the catalyst carrier housing of the catalytic converter, welds the halves from the left and right, and forms the weld on the upper surface so that it extends in the longitudinal direction of the vehicle A heat shield structure of an exhaust path provided with a heat shield along the exhaust pipe,
The heat shield plate is
One end is attached to at least one of the exhaust pipe mounting seat of the cylinder head and the mounting flange of the exhaust pipe connected to the cylinder head, and the other end is attached to the catalyst carrier accommodating portion of the catalytic converter,
And the intermediate region is unevenly arranged on the arrangement side of the peripheral device that requires heat shielding in the vehicle width direction, and has a shape that extends from the opposite side to the other end with respect to the arrangement side of the intermediate region, heat insulating structure of the exhaust path, wherein a weld is to notch formed so as to be exposed to the front side of the vehicle.