Exhaust system of an internal combustion engine

Abstract

This technology provides an effective solution for simultaneously suppressing thermal damage to differential pressure sensor piping and preventing the freezing of condensed water within the piping. [Solution] The exhaust system of an internal combustion engine includes a particulate filter positioned in the middle of the exhaust pipe, upstream piping connected to the exhaust pipe upstream of the particulate filter, downstream piping connected to the exhaust pipe downstream of the particulate filter, a differential pressure sensor to which the upstream and downstream piping are connected, and a heat insulator covering at least the portion of the exhaust pipe upstream of the particulate filter. The heat insulator is composed of a two-layer structure formed by stacking a pair of heat-shielding members. The upstream and downstream piping are configured to pass between the pair of heat-shielding members in the heat insulator.

Description

Technical Field

[0001] The present disclosure relates to an exhaust system of an internal combustion engine.

Background Art

[0002] In an exhaust system in which a particulate filter is disposed in the middle of an exhaust pipe of an internal combustion engine, there is known one provided with a differential pressure sensor for detecting a differential pressure between an exhaust pressure upstream of the particulate filter and an exhaust pressure downstream of the particulate filter (see, for example, Patent Documents 1 to 3).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present disclosure is to provide an effective technique for achieving both suppression of heat damage to the piping of a differential pressure sensor and suppression of freezing of condensed water in the piping.

Means for Solving the Problems

[0005] One aspect of the present disclosure is an exhaust system of an internal combustion engine. In that case, the exhaust system of the internal combustion engine is, for example, a particulate filter disposed in the middle of an exhaust pipe of the internal combustion engine, an upstream-side pipe connected to the exhaust pipe upstream of the particulate filter, a downstream-side pipe connected to the exhaust pipe downstream of the particulate filter, A differential pressure sensor connected to the upstream and downstream piping detects the differential pressure between the exhaust pressure upstream of the particulate filter and the exhaust pressure downstream of the particulate filter, A heat insulator covering at least the portion of the exhaust pipe upstream of the particulate filter, Equipped with, The heat insulator is composed of a two-layer structure in which a pair of heat-shielding members are stacked, The upstream and downstream piping may be configured to pass between the pair of heat-shielding members in the heat insulator. [Effects of the Invention]

[0006] According to this disclosure, it is possible to provide a technology that is effective in achieving both the suppression of heat damage to the piping of differential pressure sensors and the suppression of freezing of condensed water inside the piping. [Brief explanation of the drawing]

[0007] [Figure 1] This diagram schematically shows an example of the configuration of the exhaust system of an internal combustion engine in an embodiment. [Figure 2] This is a cross-sectional view showing an example of the configuration of a heat insulator in an embodiment. [Modes for carrying out the invention]

[0008] As an exhaust system for an internal combustion engine (gasoline engine) that uses gasoline as fuel, Some known examples include those equipped with a GPF (Gasoline Particulate Filter) in the middle of the exhaust pipe. In such exhaust systems, differential pressure sensors may be installed to detect the removal of the GPF (Ground Pressure Filter). The differential pressure sensor is connected to the upstream piping connected to the exhaust pipe upstream of the GPF and the downstream piping connected to the exhaust pipe downstream of the GPF, and detects the differential pressure between the exhaust pressure upstream of the GPF and the exhaust pressure downstream of the GPF.

[0009] Furthermore, the downstream piping extends further away from the internal combustion engine (the heat source) than the upstream piping (downstream of the GPF), making it more susceptible to external temperature changes. Therefore, in environments where the ambient temperature is below freezing, such as in cold regions, condensed water could freeze within the downstream piping. If condensed water freezes, the passage within the downstream piping could become blocked, potentially preventing the differential pressure sensor from accurately detecting the differential pressure. Additionally, due to space constraints in the vehicle, both the upstream and downstream piping are often positioned close to the exhaust pipe, running alongside it. In such cases, the upstream and downstream piping could suffer thermal damage from the heat emitted from the exhaust pipe. Therefore, measures are needed to simultaneously suppress the freezing of condensed water in the upstream and downstream piping, and to suppress thermal damage to the upstream and downstream piping.

[0010] Therefore, in the exhaust system for an internal combustion engine according to this disclosure, the heat insulator covering the exhaust pipe at least upstream of the particulate filter is configured with a two-layer structure formed by stacking a pair of heat-shielding members. Furthermore, in the exhaust system for an internal combustion engine according to this disclosure, the upstream and downstream pipes are configured to pass between the pair of heat-shielding members of the heat insulator. This reduces the amount of heat transferred from the exhaust pipe to the upstream and downstream pipes, and also reduces the amount of heat released into the atmosphere from the upstream and downstream pipes. Thus, the exhaust system for an internal combustion engine according to this disclosure can achieve both the suppression of heat damage to the upstream and downstream pipes and the suppression of freezing of condensed water inside the upstream and downstream pipes.

[0011] <Embodiment> The following describes specific embodiments of the present invention with reference to the drawings. The dimensions, materials, shapes, relative arrangements, etc., of the components described in these embodiments are not intended to limit the technical scope of the invention to those unless otherwise specified.

[0012] (Overview of the exhaust system) In this embodiment, an example of applying the exhaust system according to the present disclosure to an internal combustion engine for a vehicle will be described. The vehicle may be, for example, a vehicle (internal combustion engine vehicle) driven by an internal combustion engine as a prime mover. Note that the vehicle is not limited to an internal combustion engine vehicle, and may be a vehicle (HEV (Hybrid Electric Vehicle) or PHEV (Plug-in Hybrid Electric Vehicle)) driven by an internal combustion engine and an electric motor as prime movers, or a BEV (Battery Electric Vehicle) equipped with an internal combustion engine as a generator.

[0013] FIG. 1 is a diagram schematically showing an example of the configuration of an exhaust system Es1 of an internal combustion engine 1 in this embodiment. The internal combustion engine 1 may be, for example, a spark ignition internal combustion engine (gasoline engine) having a plurality of cylinders 10. The exhaust system Es1 includes, for example, an exhaust manifold 2, a catalyst casing 3, an exhaust pipe 4, a filter casing 5, and a heat insulator 6.

[0014] The exhaust manifold 2 is connected to the internal combustion engine 1 and is configured to allow the burned gas burned in the plurality of cylinders 10 of the internal combustion engine 1 to flow therethrough. For example, the exhaust manifold 2 includes a plurality of branch pipes through which the burned gas (exhaust gas) burned in each of the plurality of cylinders 10 of the internal combustion engine 1 flows, and a collecting pipe (collector) that combines the exhaust gases flowing through the plurality of branch pipes. It may be configured to include.

[0015] The catalyst casing 3 is connected to the downstream side (collecting pipe) of the exhaust manifold 2 and is configured to purify the exhaust gas flowing out from the exhaust manifold 2. For example, the catalyst casing 3 houses an exhaust purification catalyst such as a three-way catalyst in a cylindrical casing, and purifies exhaust components such as hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NO x ) and the like. It may be configured to be purified.

[0016] The exhaust pipe 4 is connected to the downstream side of the catalyst casing 3 and is configured to allow the exhaust gas flowing out from the catalyst casing 3 to flow through. In one example, the exhaust pipe 4 may be composed of a cylindrical metal pipe.

[0017] The filter casing 5 is disposed in the middle of the exhaust pipe 4 and houses a GPF (Gasoline Particulate Filter). The GPF is a filter for collecting particulate matter (PM (Particulate Matter)) contained in the exhaust gas.

[0018] The heat insulator 6 is a heat-insulating cover formed to cover the upper part (the part in the front direction in FIG. 1) of the exhaust manifold 2 and the catalyst casing 3. Note that the heat insulator 6 may be configured to cover not only the upper part of the exhaust manifold 2 and the catalyst casing 3 but also the entire upper, lower, left, and right sides of the exhaust manifold 2 and the catalyst casing 3. Further, the heat insulator 6 may be configured to cover only the exhaust manifold 2 among the exhaust manifold 2 and the catalyst casing 3. Details of the heat insulator 6 in the present embodiment will be described later.

[0019] Also, the exhaust system Es1 in the present embodiment further includes a differential pressure sensor 7, an upstream pipe 70, a downstream pipe 71, and a heat exchange part 8. The differential pressure sensor 7 is a sensor used for calculating the amount of PM collected by the GPF in the filter casing 5 and detecting the removal of the GPF, and detects the differential pressure between the exhaust pressure upstream of the GPF and the exhaust pressure downstream of the GPF. In the example shown in FIG. 1, the differential pressure sensor 7 is fixed to the internal combustion engine 1. Note that the position where the differential pressure sensor 7 is fixed is not limited to the position illustrated in FIG. 1 and can be appropriately changed according to the implementation mode.

[0020] In this embodiment, one end of the upstream pipe 70 and one end of the downstream pipe 71 are connected to the differential pressure sensor 7. The other end of the upstream pipe 70 is connected to the exhaust pipe 4 upstream of the filter casing 5, and transmits the exhaust pressure upstream of the GPF to the differential pressure sensor 7. The other end of the downstream pipe 71 is connected to the exhaust pipe 4 downstream of the filter casing 5, and transmits the exhaust pressure downstream of the GPF to the differential pressure sensor 7. In this embodiment, the upstream pipe 70 and the downstream pipe 71 are arranged in close proximity to the exhaust manifold 2, the catalytic converter casing 3, and the exhaust pipe 4, along the direction of exhaust flow. Details of the arrangement of the upstream pipe 70 and the downstream pipe 71 in this embodiment will be described later.

[0021] In this embodiment, the combination of the exhaust manifold 2, the catalytic converter casing 3, and the exhaust pipe 4 corresponds to the "exhaust pipe" according to this disclosure.

[0022] (Heat insulator) Here, an example of the configuration of the heat insulator 6 in this embodiment will be described with reference to Figure 2. Figure 2 is a cross-sectional view showing an example of the configuration of the heat insulator 6. Note that Figure 2 is a cross-sectional view (a cross-sectional view from the bottom to the top in Figure 1) taken from the downstream side in the axial direction of the exhaust pipe 4 in the arrangement illustrated in Figure 1.

[0023] As shown in Figure 2, the heat insulator 6 in this embodiment is composed of a two-layer structure formed by stacking a pair of heat shields 60a-60b. The pair of heat shields 60a-60b are formed from an aluminum alloy or the like with enhanced heat shielding properties. The pair of heat shields 60a-60b are fixed to each other by crimping or screw fastening. In this embodiment, the portions of the upstream piping 70 and the downstream piping 70 that are located close to the exhaust manifold 2 and the catalytic converter casing 3 (portions 70a-71a shown by dashed lines in Figure 1) are configured to pass between the pair of heat shields 60a-60b of the heat insulator 6. In other words, the heat insulator 6 is configured to sandwich the above portion 70a of the upstream piping 70 and the above portion 71a of the downstream piping 71 with the pair of heat shields 60a-60b.

[0024] The heat insulator 6 may be configured to cover the filter casing 5 to a certain point or to its downstream end. In that case, in addition to the portion 71a of the downstream piping 71, the portion downstream of the portion 71a should also be sandwiched between the pair of heat shields 60a-60b of the heat insulator 6.

[0025] (Operation and effects of this embodiment) In the exhaust system Es1 of this embodiment, the portions 70a-71a of the upstream piping 70 and the downstream piping 71 that are located close to the exhaust manifold 2 and the catalytic converter casing 3 are configured to pass between a pair of heat shields 60a-60b of the heat insulator 6. As a result, heat transfer from the exhaust manifold 2 and the catalytic converter casing 3 to these portions 70a-71a is suppressed by the heat shields 60b. Consequently, thermal damage to the upstream and downstream piping caused by the heat emitted from the exhaust manifold 2 and the catalytic converter casing 3 can be suppressed. Furthermore, heat dissipation from these portions 70a-70b into the atmosphere (cooling of these portions 70a-70b by the atmosphere) is suppressed by the heat shields 60a. Consequently, in environments where the ambient temperature is below freezing, the freezing of condensed water inside the upstream piping 70 and the downstream piping 71 can be suppressed.

[0026] Therefore, the exhaust system Es1 in this embodiment can achieve both the suppression of heat damage to the upstream pipe 70 and the downstream pipe 71, and the suppression of freezing of condensed water in the upstream pipe 70 and the downstream pipe 71. Furthermore, with the exhaust system Es1 in this embodiment, the positions of the upstream pipe 70 and the downstream pipe 71 can be fixed by the heat insulator 6, eliminating the need to provide parts (for example, brackets, etc.) for fixing the upstream pipe 70 and the downstream pipe 71. This can lead to a reduction in the number of parts in the exhaust system Es1 and an improvement in the productivity of the exhaust system Es1.

[0027] <Other> In the embodiments described above, a spark-ignition type internal combustion engine (gasoline engine) was given as an example of an internal combustion engine to which the exhaust system according to this disclosure is applied, but a compression-ignition type internal combustion engine (diesel engine) may also be used. In that case, a DPF (Diesel Particulate Filter) may be housed inside the filter casing 5 instead of a GPF. Furthermore, in the embodiments described above, a spark-ignition type internal combustion engine (gasoline engine) was given as an example of an internal combustion engine to which the exhaust system according to this disclosure is applied, but a compression-ignition type internal combustion engine (diesel engine) may also be used. Although the example given shows a configuration in which the catalyst casing 3 is positioned upstream of the filter casing 5, the catalyst casing 3 may be omitted. In that case, it is sufficient for the exhaust gas purification catalyst to be supported on the GPF. [Explanation of Symbols]

[0028] 1...Internal combustion engine, 10...Cylinder, 2...Exhaust manifold, 3...Catalytic converter casing, 4...Exhaust pipe, 5...Filter casing, 6...Heat insulator, 60a-60b...Heat shield, 7...Differential pressure sensor, 70...Upstream piping, 71...Downstream piping, Es1...Exhaust system

Claims

[Claim 1] A particulate filter is placed in the middle of the exhaust pipe of an internal combustion engine, Upstream piping connected to the exhaust pipe upstream of the particulate filter, A downstream piping connected to the exhaust pipe downstream of the particulate filter, A differential pressure sensor connected to the upstream and downstream piping detects the differential pressure between the exhaust pressure upstream of the particulate filter and the exhaust pressure downstream of the particulate filter, A heat insulator covering at least the portion of the exhaust pipe upstream of the particulate filter, Equipped with, The heat insulator is composed of a two-layer structure in which a pair of heat-shielding members are stacked, The upstream piping and the downstream piping are configured to pass between the pair of heat shielding members in the heat insulator. The exhaust system of an internal combustion engine.

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