JP2017172390A - Exhaust pipe structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust pipe structure which is suppressed in a decrease in a flow passage cross section area in an exhaust pipe caused by a freeze of condensed water by a simple structure.SOLUTION: In the exhaust pipe structure, a double-pipe structure 39 which is composed of an exhaust pipe 20 and an outer pipe 38 is arranged in a lowest region 20A of the exhaust pipe 20, and a water retention member 40 composed of glass wool is arranged between the exhaust pipe 20 and the outer pipe 38. A plurality of penetration holes 42 penetrating an internal peripheral face and an external peripheral face are formed at the exhaust pipe 20 having the double-pipe structure 39 at prescribed intervals in a peripheral direction. Therefore, even if the condensed water generated inside the exhaust pipe 20 is not discharged by an exhaust gas, remains in the exhaust pipe 20, and is collected in the lowest region 20A, the condensed water is absorbed to the water retention member 40 from the penetration holes 42, and a water level of the condensed water in the exhaust pipe 20 is lowered. As a result, a decrease in a flow passage cross section area of the exhaust pipe 20 caused by a freeze of the condensed water is suppressed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an exhaust pipe structure.

  In an automobile, for example, exhaust gas from an engine or the like disposed at the front of the vehicle is discharged to the vehicle rear side through an exhaust pipe disposed at the lower portion of the vehicle. Some of the moisture in the exhaust gas becomes water droplets inside the exhaust pipe, but when the flow rate of the exhaust gas is sufficient, it is discharged to the outside together with the exhaust gas from the end of the exhaust pipe.

  However, when the travel time of the vehicle is short or when the flow rate of the exhaust gas is small, such as when the motor of the hybrid vehicle is running, water droplets in the exhaust pipe are not completely discharged and remain as condensed water in the exhaust pipe. The condensed water remaining in the exhaust pipe may be frozen in the exhaust pipe when the ambient temperature is low. Due to this freezing, the cross-sectional area of the flow path through which the exhaust gas in the exhaust pipe can pass is reduced (the flow path is narrowed), the pressure loss is increased, and the engine output may be reduced or noise may be generated.

  For the purpose of suppressing the reduction of the cross-sectional area of the flow path in the exhaust pipe due to such condensate freezing, the following is applied to the exhaust pipe of the combustion heater provided in the electric vehicle. A configuration is proposed. That is, there has been proposed a system in which a drain outlet is provided at the lowest portion of the heater exhaust pipe having the lowest height in the vertical direction and the lowest portion of the exhaust pipe is positioned on the vehicle front side (see Patent Document 1). By configuring in this way, high temperature exhaust gas is supplied to the lowest part where the condensed water collects, and even when the condensed water freezes, it can be quickly melted to suppress a reduction in the cross-sectional area of the exhaust pipe. Is described.

JP-A-10-131745

  However, changing the lowest part of the exhaust pipe to the front side of the vehicle as in the above proposal requires not only changing the shape of the exhaust pipe but also the arrangement of other parts of the vehicle. Design changes are necessary. There is room for improvement in this regard.

  Also, in recent years, the exhaust gas temperature in the exhaust pipe has decreased due to the high efficiency of exhaust heat recovery devices and engines installed in the middle of the exhaust gas exhaust pipe. The problem of decreasing is becoming more apparent.

  In view of the above facts, an object of the present invention is to provide an exhaust pipe structure that has a simple structure and that suppresses a reduction in the cross-sectional area of the flow path in the exhaust pipe due to freezing of condensed water.

  The invention according to claim 1 is formed in an exhaust pipe for leading exhaust gas discharged from a power source to the outside, and at least a minimum region in which the height in the vehicle vertical direction of the exhaust pipe is minimum, and the exhaust gas passes through the exhaust pipe. A double pipe structure composed of an inner pipe, an outer pipe disposed outside the inner pipe, a water retention member disposed between the inner pipe and the outer pipe, and the inner pipe And a through hole formed at least in a portion excluding the upper end portion and communicating the inner peripheral surface and the outer peripheral surface of the inner tube.

  In this exhaust pipe structure, when the flow rate of the exhaust gas is small, condensed water may be generated in the exhaust pipe due to the exhaust gas discharged from the power source and may remain in the exhaust pipe. At this time, the condensed water gathers in the lowest region where the height in the vehicle vertical direction in the exhaust pipe is the lowest. By the way, at least the lowest region of the exhaust pipe has a double pipe structure. The double pipe structure includes an inner pipe through which exhaust gas passes and an outer pipe disposed on the outer side thereof, and a water retention member is disposed between the inner pipe and the outer pipe. In addition, a through hole that communicates the inner surface and the outer surface of the inner tube is formed in a portion excluding at least the upper end of the inner tube. Therefore, the condensed water collected in the lowest region of the exhaust pipe is sucked into the water retaining member through the through hole formed in the inner pipe of the double structure portion. As a result, the amount of condensed water remaining in the exhaust pipe is reduced, and when the ambient temperature is low, it is suppressed that the condensed water in the exhaust pipe freezes and the flow passage cross-sectional area of the exhaust pipe is reduced. The cross-sectional area of the inner pipe is the same as the cross-sectional area of the portion other than the double pipe structure of the exhaust pipe.

  The through hole is preferably formed on the lower side of the exhaust pipe, but if it is formed at a place other than the upper end, the condensed water moves to the water retaining member through the through hole, and the amount of condensed water in the exhaust pipe (Water level) can be reduced.

  Since invention of Claim 1 was set as the said structure, it can suppress with a simple structure that condensed water freezes and the flow-path cross-sectional area in an exhaust pipe is reduced.

It is a schematic explanatory drawing which shows the exhaust pipe structure which concerns on 1st Embodiment of this invention. It is the sectional view on the AA line of FIG. It is a schematic explanatory drawing which shows the exhaust pipe structure which concerns on 2nd Embodiment of this invention.

[First Embodiment]
An exhaust pipe structure according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 2. In this embodiment, the exhaust pipe structure 10 is applied to an exhaust system of a hybrid vehicle (HV (Hybrid Vehicle) vehicle).

  Hereinafter, in each drawing, an arrow FR indicates the front of the vehicle, an arrow UP indicates the vehicle upper direction, and an arrow W indicates the vehicle width direction. Moreover, the arrow in the figure indicates the flow of exhaust gas. Various components are attached to the inside of the exhaust pipe structure, but only the components related to the present embodiment are illustrated, and other components are not illustrated.

  As shown in FIG. 1, the vehicle according to the present embodiment includes an engine 12 and a motor 14.

  The engine 12 has an intake pipe 18 and an exhaust pipe 20 connected to an upper portion of a cylinder 16. A throttle valve 22 is provided in the intake pipe 18. Therefore, when the throttle valve 22 is opened, the outside air flows from the intake pipe 18 due to the negative pressure of the engine 12 and is taken into the combustion chamber of the engine 12. Further, the exhaust gas generated by the combustion of the engine 12 is discharged from the exhaust port of the engine 12 to the outside through the exhaust pipe 20.

  The vehicle according to the present embodiment can also be driven by the motor 14. For example, the motor 14 is connected to the crankshaft 24 via a clutch mechanism or the like, and the drive of the motor 14 is transmitted to the crankshaft 24 by connection of the clutch mechanism or the like. Therefore, the traveling by the engine 12 and the traveling by the motor 14 can be switched by controlling the HV drive distribution device including the clutch mechanism.

  The exhaust pipe 20 is disposed on the lower side of the vehicle body floor panel from the front of the vehicle toward the rear of the vehicle, but on the way, the catalyst device 26, the exhaust heat recovery device 28, and the muffler 30 are disposed from the upstream side. ing.

  The catalyst device 26 purifies harmful components in the exhaust gas discharged from the engine 12 by oxidation / reduction.

  The exhaust heat recovery unit 28 recovers the heat of the exhaust gas of the engine 12 of the vehicle and uses it for heating and promoting warming of the engine 12. Specifically, the exhaust heat recovery device 28 is connected to the heater core 32 and the water pump (W / P) 34 (engine 12) through a circulation flow path 36. Therefore, the cooling water for cooling the engine 12 is configured to be directed from the engine 12 to the exhaust heat recovery device 28 by the water pump (W / P) 34, then to the heater core 32, and back to the engine 12. Yes. That is, the heat of the exhaust gas is recovered by the exhaust heat recovery device 28 to raise the temperature of the cooling water, which is used for the heat source of the heater, the warming up of the engine 12, and the like.

  The muffler 30 reduces exhaust noise generated when the exhaust gas discharged from the engine 12 is discharged to the outside.

  By the way, the exhaust pipe 20 is arranged along the front-rear direction of the vehicle at the lower part of the vehicle body. However, since the exhaust pipe 20 passes below the fuel tank, the height of the exhaust pipe 20 between the exhaust heat recovery device 28 and the muffler 30 is high. The minimum area 20A is the minimum. In this lowest region 20A, an outer pipe 38 is provided on the outer side (outer periphery) of the exhaust pipe 20 so that the exhaust pipe 20 has a double pipe structure. A portion of the exhaust pipe 20 and the outer pipe 38 having a double pipe structure is referred to as a double pipe structure portion 39. The exhaust pipe 20 and the outer pipe 38 constituting the double pipe structure 39 correspond to the inner pipe and the outer pipe of the present invention, respectively.

  As shown in FIG. 2, the outer pipe 38 is disposed so as to be concentric with the exhaust pipe 20, and has a larger diameter than the exhaust pipe 20. A water retention member 40 made of glass wool is disposed between the outer peripheral surface of the exhaust pipe 20 and the inner peripheral surface of the outer pipe 38. Further, the exhaust pipe 20 of the double pipe structure portion 39 is formed with a plurality of through holes 42 communicating with the inner peripheral surface and the outer peripheral surface of the exhaust pipe 20 at predetermined intervals along the circumferential direction of the exhaust pipe 20. Yes. Further, a plurality of through holes 42 are provided at predetermined intervals along the axial direction of the exhaust pipe 20 in the exhaust pipe 20 of the double pipe structure 39.

The operation of the exhaust pipe structure 10 configured as described above will be described.
First, when the engine is running, the throttle valve 22 is opened, so that outside air is supplied to the engine 12 and exhaust gas from the engine 12 is discharged to the exhaust pipe 20. Exhaust gas that has flowed into the exhaust pipe 20 is removed of harmful components in the catalyst device 26, is subjected to heat exchange in the exhaust heat recovery device 28, and is then discharged to the outside through the muffler 30.

  At this time, when the rotational speed of the engine 12 is high and the flow rate of the exhaust gas in the exhaust pipe 20 is high, even if moisture contained in the exhaust gas becomes water droplets in the exhaust pipe 20, Discharged.

  On the other hand, when the rotational speed of the engine 12 is low or the traveling time of the vehicle is short, water droplets generated in the exhaust pipe 20 cannot be completely discharged to the outside together with the exhaust gas. May remain as condensed water. Condensed water collects in the lowest region 20 </ b> A where the height in the vehicle vertical direction is the lowest in the exhaust pipe 20.

  The condensed water collected in the lowest region 20A is disposed between the exhaust pipe 20 and the outer pipe 38 through a through hole 42 formed in the exhaust pipe 20 of the double pipe structure 39, as shown in FIG. The water retaining member 40 is sucked and held. Accordingly, the water level of the condensed water collected in the lowest region 20A of the exhaust pipe 20 is lowered, and it is possible to suppress the exhaust gas flow path in the exhaust pipe 20 from being narrowed by freezing of the condensed water.

  In particular, the water retention member 40 made of glass wool can suck condensed water to a position higher than the water level of the condensed water in the exhaust pipe 20 due to the surface tension between the condensed water and glass wool, and therefore remains in the exhaust pipe 20. The water level of the condensed water can be further reduced.

  Further, the exhaust pipe structure 10 is provided with a double pipe structure part 39 in the lowest region 20A of the exhaust pipe 20, and a water retention member 40 is disposed between the exhaust pipe 20 and the outer pipe 38 of the double pipe structure part 39. ing. That is, the water retaining member 40 is disposed in the portion where the condensed water is most concentrated and the water level of the condensed water in the exhaust pipe 20 is the highest, and the through hole 42 is formed in the exhaust pipe 20. Therefore, in the lowest region 20A where the flow passage cross-sectional area of the exhaust pipe 20 is expected to decrease most when the condensed water is frozen, the exhaust pipe 20 is sucked and held from the through hole 42 to the water retaining member 40. It is possible to suppress a decrease in the inner channel cross-sectional area.

  Further, since a plurality of through holes 42 formed in the exhaust pipe 20 are formed at predetermined intervals in the circumferential direction, the condensed water is moved from the exhaust pipe 20 to the water retaining member 40 regardless of the level of the condensed water. be able to. In particular, since the through hole 42 is also formed at the lowermost part of the exhaust pipe 20 (see FIG. 2), the condensed water is reliably moved from the through hole 42 to the water retaining member 40 even when the level of the condensed water is low. be able to.

  Further, in the vehicle to which the exhaust pipe structure 10 in the present embodiment is applied, the exhaust heat recovery device 28 is provided on the flow path of the exhaust pipe 20, so that the temperature of the exhaust gas is downstream of the exhaust heat recovery device 28. This further decreases the possibility that condensed water is generated in the exhaust pipe 20. However, since the lowest region 20A of the exhaust pipe 20 on the downstream side of the exhaust heat recovery device 28 is a double pipe structure 39 and the water retention member 40 is disposed in the double pipe structure 39, the condensed water Even if it occurs more, condensed water is sucked into the water retaining member 40 through the through hole 42 and held.

  That is, by disposing the exhaust heat recovery device 28 in the exhaust pipe 20, while reducing the exhaust gas temperature, the flow cross-sectional area of the exhaust pipe 20 is reduced by freezing due to the increase in condensed water accompanying the temperature decrease of the exhaust gas. Can be suppressed.

  Similarly, when the motor travels, exhaust gas is discharged from the exhaust pipe 20 by rotating the crankshaft 24 by the rotation of the motor 14, but the exhaust gas becomes low temperature because the engine 12 is not driven. Also in this case, the condensed water remains in the exhaust pipe 20, and the condensed water collects in the lowest region 20A. However, the condensed water is absorbed and retained by the water retaining member 40 from the through hole 42 formed in the exhaust pipe 20. Therefore, the water level of the condensed water remaining in the exhaust pipe 20 is lowered, and even if the condensed water freezes, the exhaust gas flow path (area) of the exhaust pipe 20 is suppressed from being narrowed.

  As described above, in any case, the double pipe structure 39 (outer pipe 38) is provided in the lowest region 20A of the exhaust pipe 20, and the water retaining member 40 is provided therein. The decrease in the cross-sectional area of the 20 channels is suppressed, and NV performance (noise vibration performance) is improved and radiation noise is reduced.

  Moreover, since the exhaust pipe 20 is wound and kept warm by the water retaining member 40 made of glass wool in the lowest region 20A, the condensed water is further suppressed from being frozen in the lowest region 20A due to the low ambient temperature.

  Furthermore, since the exhaust pipe structure 10 according to the present embodiment has a double pipe structure in which only the lowest region 20A of the exhaust pipe 20 is provided with the outer pipe 38 disposed outside the exhaust pipe 20, the design of an existing vehicle is used. There is no need to make significant changes. In other words, it is possible to suppress a reduction in the cross-sectional area of the exhaust pipe 20 due to freezing of condensed water with a simple structure in which the outer pipe 38 is locally added to the existing exhaust pipe 20.

  In the present embodiment, the double-pipe structure portion 39 including the exhaust pipe 20 and the outer pipe 38 is provided in the lowest area 20A of the exhaust pipe 20, but the lowest area 20A of the exhaust pipe 20 is expanded more than the other parts. The double pipe structure 39 may be formed by providing an inner pipe having the same diameter (same cross section) as the other part of the exhaust pipe 20 inside the enlarged diameter part. Also in this case, the same operational effects as in the present embodiment can be obtained.

  Moreover, although the through-hole 42 formed in the exhaust pipe 20 is formed in multiple numbers over the perimeter at predetermined intervals in the circumferential direction, it is not limited to this. In the cross section of the exhaust pipe 20, it should just be formed in the part except at least the upper end part, and the number is not specifically limited. However, when the through hole 42 is formed only in the upper end portion of the exhaust pipe 20, the condensed water cannot move to the water retaining member 40 even when the condensed water in the exhaust pipe 20 becomes full. There is no effect.

[Second Embodiment]
An exhaust pipe structure 50 according to a second embodiment of the present invention will be described. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the present embodiment, the double-pipe structure 39 is formed in a range from a slightly upstream side of the lowest region 20 </ b> A of the exhaust pipe 20 to the muffler 30. A water retaining member 40 made of glass wool is disposed between the exhaust pipe 20 and the outer pipe 38 constituting the double pipe structure 39. Further, in the exhaust pipe 20 of the double-pipe structure portion 39, through holes 42 communicating the inner peripheral surface and the outer peripheral surface are spaced apart along the circumferential direction, and are spaced apart along the axial direction. A plurality are formed.

  As described above, the double pipe structure 39 is provided not only at the lowest region 20A of the exhaust pipe 20 but also extending to the front and back thereof, so that the condensed water can be sucked into the water retaining member 40 more easily and condensed. It is possible to further suppress the narrowing of the flow path of the exhaust pipe 20 due to water freezing (the cross-sectional area of the flow path is reduced).

  In the series of embodiments, an example in which the exhaust pipe structure is applied to an HV vehicle has been described. However, the present invention is not limited to this. The present invention can also be applied to a vehicle that runs only with an engine or a vehicle that runs only with a motor.

  Further, in the series of embodiments, the exhaust pipe structure including the exhaust heat recovery device 28 has been described. However, the exhaust pipe structure having the exhaust heat recovery device 28 may be applied.

  Furthermore, in the series of embodiments, the water retaining member 40 is formed from glass wool, but the material is not limited to this as long as the material has water retention. For example, the water retaining member 40 may be formed from ceramic wool, porous board, or diatomaceous earth.

10, 50 Exhaust pipe structure 12 Engine (power source)
14 Motor (Power source)
20 Exhaust pipe (inner pipe)
38 Outer pipe 39 Double pipe structure 40 Water retaining member 42 Through hole

Claims (1)

An exhaust pipe for leading the exhaust gas discharged from the power source to the outside;
A double pipe structure formed of an inner pipe through which the exhaust gas passes, and an outer pipe disposed outside the inner pipe, which is formed in at least the lowest region in the vehicle vertical direction of the exhaust pipe. And
A water retaining member disposed between the inner tube and the outer tube;
A through hole formed at least in a portion excluding the upper end of the inner tube, and communicating the inner peripheral surface and the outer peripheral surface of the inner tube;
Exhaust pipe structure with