Heat shielding structure of an internal combustion engine

Abstract

The present invention provides a heat shielding structure for an internal combustion engine that can suppress damage to the first sensor due to overheating of the heat shield plate. [Solution] In the heat shield structure for an internal combustion engine according to the present invention, the heat shield plate 6, which shields the first sensor (A / F sensor S1) from the heat source (exhaust turbine) and protects the first sensor, is not directly attached to the manifold converter 1, but is attached to the first piping 51 connected to the manifold converter 1. Therefore, there is no risk of the heat from the manifold converter 1 being directly transmitted to the heat shield plate 6, and it is possible to suppress overheating of the heat shield plate 6. As a result, damage to the A / F sensor S1 due to heat from the heat shield plate 6 can be suppressed.

Description

Technical Field

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[0001] The present invention relates to a heat insulation structure for an internal combustion engine.

Background Art

[0002] ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Therefore, the present invention was devised in view of the technical problems related to the conventional heat shield structure for internal combustion engines, and aims to provide a heat shield structure for an internal combustion engine that can suppress damage to the first sensor due to overheating of the heat shield plate. [Means for solving the problem]

[0008] In one aspect, the present invention comprises: an exhaust pipe connected to an internal combustion engine; a heat source arranged around the internal combustion engine and located near the exhaust pipe; piping connected to the exhaust pipe and passing between the exhaust pipe and the heat source; a first sensor connected to the exhaust pipe; and a heat shield supported by the piping and positioned between the exhaust pipe and the heat source, which blocks heat radiation from the heat source to the first sensor. [Effects of the Invention]

[0009] According to the present invention, the heat shield is attached to a pipe connected to the exhaust pipe and passing between the exhaust pipe and the heat source. In this way, the heat shield is attached to the pipe extending from the exhaust pipe, rather than directly to the exhaust pipe, so that the heat from the exhaust pipe is not directly transferred to the heat shield, and overheating due to the temperature rise of the heat shield can be suppressed. This makes it possible to suppress damage to the first sensor due to heat dissipation by the heat shield.

[0010] Furthermore, since the heat shield is attached to the piping extending from the exhaust pipe, it provides heat shielding for the first sensor, which is located away from the internal combustion engine, and there is no risk of the heat shield becoming larger compared to when it is attached to the internal combustion engine. This improves the layout of various components arranged around the internal combustion engine. [Brief explanation of the drawing]

[0011] [Figure 1] This is a front view of a manifold converter to which the heat shielding structure for an internal combustion engine according to the present invention is applied. [Figure 2] Figure 1 is a perspective view of the manifold converter shown from the left side. [Figure 3] Figure 1 is a perspective view of the manifold converter shown from the right side. [Figure 4] Figure 1 is a perspective view of the manifold converter as seen from the rear. [Figure 5] Figure 1 is a magnified perspective view of the heat shield shown in Figure 1. [Modes for carrying out the invention]

[0012] Below, one embodiment of the heat shield structure for an internal combustion engine according to the present invention will be described in detail with reference to the drawings. In this embodiment, an example will be given in which the heat shield structure for an internal combustion engine according to the present invention is applied to a manifold converter of a turbocharged automobile engine.

[0013] Figure 1 shows a front view of the manifold converter 1 of the internal combustion engine 10 according to this embodiment. Figure 2 is a perspective view of the manifold converter 1 shown in Figure 1, viewed from the left side. Figure 3 is a perspective view of the manifold converter 1 shown in Figure 1, viewed from the right side. Figure 4 is a perspective view of the manifold converter 1 shown in Figure 1, viewed from the rear side. Figure 5 shows an enlarged view of the heat shield 6 shown in Figure 1.

[0014] For example, as shown in Figures 1 to 4, the internal combustion engine 10 according to this embodiment includes an exhaust manifold (not shown) whose upstream end is connected to the exhaust port of a cylinder head (not shown) and which constitutes part of the exhaust pipe; an exhaust turbine (not shown) which serves as a heat source for a supercharger and is connected to the downstream end of the exhaust manifold; and a manifold converter 1 connected downstream of the exhaust turbine and which constitutes part of the exhaust pipe. Furthermore, a muffler (not shown) that discharges exhaust gas to the outside is connected to the second end 1b, which is the downstream end of the manifold converter 1.

[0015] The manifold converter 1 has its first end 1a, which is the upstream end, connected to the downstream side of the exhaust turbine, and is arranged in a curved shape that roughly makes a U-turn downstream of the exhaust turbine. The manifold converter 1 is integrally formed with a manifold body 2 connected to the exhaust turbine and a catalyst 3 provided downstream of the manifold body 2 and incorporating a well-known three-way catalyst.

[0016] The manifold body 2 has a generally cylindrical first end 2a connected to the exhaust turbine, which is covered together with the exhaust turbine by a heat shielding member 4 that shields the exhaust turbine from heat radiation. The heat shielding member 4 is formed by curving a thin metal plate into a generally arc shape (inverted U shape), and is placed over the exhaust turbine and the first end 2a of the manifold body from above. In other words, the heat shielding member 4 shields the exhaust turbine, which is a heat source, from heat radiation by surrounding the exhaust turbine and the upper and side portions of the first end 2a of the manifold body.

[0017] Furthermore, the manifold converter 1 is connected to a pair of differential pressure pipes, which consist of a first pipe 51 that extracts exhaust gas (exhaust pressure) from the upstream side of the catalyst 3 located downstream of the manifold body 2, and a second pipe 52 that is connected to the downstream side of the catalyst 3 and extracts exhaust gas (exhaust pressure) from the downstream side of the catalyst 3. This pair of differential pressure pipes is connected to a differential pressure sensor S2, which serves as a second sensor, fixed to the upper part of the heat shield member 4 via a bracket 7. The differential pressure sensor S2 detects the differential pressure of the exhaust gas before and after the catalyst 3, thereby enabling the detection of clogging of the exhaust gas filter.

[0018] Here, as shown in FIG. 4, the first pipe 51 is generally formed in a cylindrical shape from a metal material, and is arranged to straddle in the vertical direction the central space portion SP surrounded by the manifold body 2 that curves between both end portions of the manifold body 2. The first end portion 51a in the longitudinal direction is fastened to the downstream end portion of the manifold body 2, which is the upstream end portion of the catalyst 3, via a first nut NT1, and the second end portion 51b on the opposite side in the longitudinal direction is connected to the differential pressure sensor S2 via a cylindrical first elastic member B1 made of an elastic material such as rubber, for example. In other words, the first pipe 51 is substantially supported in a cantilevered manner by the manifold body 2 in that the first end portion 51a is fixed to the manifold converter 1 (manifold body 2) via the first nut N1 and the second end portion 51b is connected to the differential pressure sensor S2 via the first elastic member B1.

[0019] As shown in FIG. 3, the second pipe 52 is generally formed in a cylindrical shape from a metal material, and is arranged to straddle in the vertical direction the central space portion SP surrounded by the manifold body 2 that curves between both end portions of the manifold body 2. The first end portion 52a in the longitudinal direction is fastened to the downstream end portion of the catalyst 3 via a second nut N2, and the second end portion 52b on the opposite side in the longitudinal direction is connected to the differential pressure sensor S2 via a cylindrical second elastic member B2 made of an elastic material such as rubber, for example. In other words, the second pipe 52 is substantially supported in a cantilevered manner by the catalyst 3 in that the first end portion 52a is fixed to the manifold converter 1 (catalyst 3) via the second nut N2 and the second end portion 52b is connected to the differential pressure sensor S2 via the second elastic member B2.

[0020] Also, as shown in FIGS. 1 and 2, an A / F sensor S1, which is an air-fuel ratio sensor as a first sensor for detecting the air-fuel ratio, is connected to the downstream end portion of the manifold body 2 located at the upstream end portion of the catalyst 3 in the manifold body 2. The A / F sensor S1 is connected to an engine controller (not shown) and is used for appropriate combustion control of the internal combustion engine 10.

[0021] Further, in the present embodiment, a plate-shaped heat shield 6 capable of shielding heat radiation from the lower part of the exhaust turbine, which is not covered by the heat insulating member 4, is provided between the exhaust turbine and the A / F sensor S1 on the side of the internal combustion engine 10 away from the side surface 10a of the internal combustion engine 10.

[0022] The heat shield 6 is attached to the pipe closer to the A / F sensor S1 among the first pipe 51 and the second pipe 52 (the first pipe 51 in the present embodiment). Specifically, the heat shield 6 is generally formed in a rectangular shape by a thin metal plate such as aluminum with relatively high heat dissipation, and one side edge portion 61 is fixed to the first pipe 51 along it, for example, by brazing or welding.

[0023] Here, in the present embodiment, an example of a mode in which the heat shield 6 is fixed to the pair of differential pressure pipes (the first pipe 51) is illustrated, but the heat shield 6 is not limited to being fixed to the pair of differential pressure pipes (the first pipe 51). In other words, the heat shield 6 may be attached to other pipes passing near the A / F sensor S1, such as an EGR pipe (not shown) branching on the downstream side of the catalyst 3.

[0024] In this way, the heat shield 6 is arranged in the vertical direction so as to be interposed between the exhaust turbine and the A / F sensor S1 in the central space portion SP of the manifold body 2. At this time, the heat shield 6 is arranged in an inclined shape with respect to the side surface 10a of the internal combustion engine 10 such that the upper end portion is relatively more separated from the side surface 10a of the internal combustion engine 10 than the lower end portion in the vertical direction. In other words, the heat shield 6 is arranged so as to intersect at a relatively large angle (substantially a right angle in the present embodiment) with respect to the virtual line V connecting the exhaust turbine and the A / F sensor S1 between the exhaust turbine and the A / F sensor S1.

[0025] Furthermore, the heat shield 6 has a roughly elliptical recess 62 in its central portion, which is formed in a stepped manner from the exhaust turbine side toward the A / F sensor S1. In addition, the heat shield 6 has a bent portion 63 formed by cutting and bending a part of its side edge toward the internal combustion engine 10 side. In this way, the rigidity of the heat shield 6, which is formed relatively thinly, is increased by the provision of the recess 62 and the bent portion 63. The shape and number of recesses 62 can be arbitrarily changed according to the size of the heat shield 6 and the required rigidity.

[0026] (Effects of this embodiment) As described above, in the heat shield structure for the internal combustion engine according to this embodiment, the heat shield 6 is attached to the first pipe 51, which is a pipe that passes between the exhaust turbine, which is the heat source, and the A / F sensor S1, which is the first sensor, and is connected to the manifold converter 1, which is the exhaust pipe. Thus, in this embodiment, the heat shield 6 is not directly attached to the manifold converter 1, but is attached to the first pipe 51 that extends from the manifold converter 1. Therefore, there is no risk of heat from the manifold converter 1 being directly transferred to the heat shield 6, and it is possible to suppress overheating due to the temperature rise of the heat shield 6. This makes it possible to suppress damage to the A / F sensor S1 due to heat dissipation from the heat shield 6.

[0027] Furthermore, since the heat shield 6 is attached to the first pipe 51 extending from the manifold converter 1, there is no risk of the heat shield 6 becoming larger compared to when the heat shield 6 is attached to the internal combustion engine 10, when providing heat shielding for the A / F sensor S1 which is located at a position spaced apart from the side surface 10a of the internal combustion engine 10. This improves the layout of various components arranged around the internal combustion engine 10 in the engine compartment of the vehicle.

[0028] Furthermore, in this embodiment, the heat shield 6 is attached to the first pipe 51, which is closer to the A / F sensor S1, of a pair of differential pressure pipes that extract the differential pressure from the upstream and downstream sides of the catalyst 3 in the manifold converter 1. Therefore, it is possible to place the heat shield 6 near the A / F sensor S1 without increasing the size of the heat shield 6. This makes it possible to miniaturize the heat shield 6 while ensuring proper heat shielding of the A / F sensor S1 by the heat shield 6.

[0029] Furthermore, in this embodiment, the A / F sensor S1 is located near the central space SP, which is the area surrounded by the manifold converter 1 (manifold body 2) that curves in a folded manner from the outlet of the exhaust turbine, which is a supercharger. Therefore, it is susceptible to the high heat of the exhaust turbine that is trapped due to the curvature of the manifold body 2.

[0030] In contrast, in this embodiment, the heat shield 6 is supported by the first pipe 51 connected to the manifold body 2. Therefore, there is no risk of the heat shield 6 becoming hot due to direct heat transfer from the manifold body 2, and the heat shield 6 can shield the heat radiated from the exhaust turbine, thereby properly protecting the A / F sensor S1.

[0031] Furthermore, in this embodiment, the first pipe 51 is cantilevered to the manifold converter 1 (manifold body 2). Therefore, compared to the case where both ends of the first pipe 51 are supported, it is possible to suppress the amplification of vibration of the heat shield 6 due to radiated sound emitted from the internal combustion engine 10. This contributes to reducing the noise and vibration of the internal combustion engine 10.

[0032] Furthermore, the second end 51b of the first pipe 51 is connected to the differential pressure sensor S2 via the first elastic member B1. This makes it possible to suppress the problem of vibrations caused by the radiated sound of the internal combustion engine 10 being transmitted to the differential pressure sensor S2 through the first pipe 51. This protects the differential pressure sensor S2 and ensures proper sensing by the differential pressure sensor S2.

[0033] Furthermore, in this embodiment, a stepped recess 62 is provided in the center of the heat shield 6. This improves the rigidity of the heat shield 6 and makes it possible to suppress the amplification of vibrations of the heat shield 6 caused by radiated sound emitted from the internal combustion engine 10. As a result, the noise and vibration of the internal combustion engine 10 can be reduced more effectively.

[0034] Furthermore, in this embodiment, the heat shield 6 is positioned to the side of the internal combustion engine 10 between the exhaust turbine and the manifold converter 1. Therefore, the heat shield 6 can contribute to shielding the radiated sound emitted from the internal combustion engine 10. This makes it possible to more effectively reduce the noise and vibration of the internal combustion engine 10.

[0035] Furthermore, in this embodiment, the heat shield 6 is positioned at an angle to the side surface 10a of the internal combustion engine 10. This makes it possible to suppress standing waves of radiated sound emitted from the internal combustion engine 10. As a result, the noise and vibration of the internal combustion engine 10 can be reduced even more effectively.

[0036] The present invention is not limited to the configurations illustrated in the above embodiments, and can be freely modified according to, for example, the specifications of the internal combustion engine to which the present invention is applied.

[0037] In the above embodiment, an example is given in which the heat shielding target is the A / F sensor S1. However, the heat shielding structure for an internal combustion engine according to the present invention is not limited to the A / F sensor S1, as long as it is located near the exhaust turbine, which is the heat source, within the manifold converter 1, which is the exhaust pipe. In other words, the first sensor according to the present invention that is the target of heat shielding includes other sensors that are thermally affected by the exhaust turbine. Furthermore, the heat source according to the present invention is not limited to the exhaust turbine, as long as it has a thermal effect on the A / F sensor S1 that is the target of heat shielding. [Explanation of Symbols]

[0038] 1… Manifold converter (exhaust pipe) 2…Manifold body 3…Catalyst 51...First piping (a pair of differential pressure pipes) 52...Second piping (a pair of differential pressure pipes) 6… Heat shield 62…recess 10... Internal combustion engine 10a...side S1…A / F sensor (first sensor) S2... Differential pressure sensor (second sensor) B1...First elastic member (elastic member) B2...Second elastic member (elastic member)

Claims

1. The exhaust pipe connected to the internal combustion engine, A heat source arranged around the internal combustion engine and located near the exhaust pipe, A pipe connected to the exhaust pipe and passing between the exhaust pipe and the heat source, A first sensor connected to the exhaust pipe, A heat shield plate is provided, which is supported by the aforementioned piping and positioned between the exhaust pipe and the heat source, to block heat radiation from the heat source to the first sensor, A heat shield structure for an internal combustion engine equipped with the following features.

2. A heat shielding structure for an internal combustion engine according to claim 1, The exhaust pipe is equipped with a catalyst that purifies the exhaust gas flowing through it. The aforementioned piping is a pair of differential pressure pipes, the first ends in the longitudinal direction of which are connected to the upstream and downstream sides of the catalyst in the exhaust pipe, respectively, and which extract the differential pressure of the exhaust gas flowing through the exhaust pipe. The internal combustion engine has a second sensor that detects the differential pressure of the exhaust pressure between the upstream and downstream sides of the catalyst, which is taken out by the pair of differential pressure pipes. The heat shield is supported by the pipe of the pair of differential pressure pipes that is closer to the first sensor. Heat shielding structure for internal combustion engines.

3. A heat shielding structure for an internal combustion engine according to claim 2, The heat source is a supercharger connected to the internal combustion engine. The exhaust pipe is provided curved in a folded manner from the outlet of the supercharger, The first sensor is positioned near the region surrounded by the folded exhaust pipe. Heat shielding structure for internal combustion engines.

4. A heat shielding structure for an internal combustion engine according to claim 2, The piping is cantilevered and fixed to the exhaust pipe by having its first longitudinal end fixed to the exhaust pipe and its second opposite end connected to the second sensor via an elastic member. Heat shielding structure for internal combustion engines.

5. A heat shielding structure for an internal combustion engine according to any one of claims 1 to 4, The heat shield has a recess in the center that is stepped. Heat shielding structure for internal combustion engines.

6. A heat shielding structure for an internal combustion engine according to any one of claims 1 to 4, The heat shield is positioned between the heat source and the exhaust pipe, on the side of the internal combustion engine. Heat shielding structure for internal combustion engines.

7. A heat shielding structure for an internal combustion engine according to claim 6, The heat shield is arranged at an inclination with respect to the side surface of the internal combustion engine. Heat shielding structure for internal combustion engines.

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