JP4995706B2 - Exhaust heat recovery device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a waste heat recovery device in which an exhaust gas current can be certainly switched by a simple structure. <P>SOLUTION: The waste heat recovery device is equipped with an exhaust gas duct 2 disposed in an exhaust gas channel from an internal combustion engine to guide exhaust gas from an upstream side to a downstream side, a waste heat recovery section 4 for performing heat exchange between the exhaust gas and a heat exchanging medium, and a switching valve 31 for cutting off the exhaust gas duct 2 to make the exhaust gas current shift to a current passing through the waste heat recovery section 4. The waste heat recovery section 4 is arranged while covering the outside of the exhaust gas duct 2. An outlet 12 and an inlet 14 which radially open are formed at an outer circumference of the exhaust gas duct 2, and the outlet 12 and the inlet are formed in vicinity with respect to the axial direction of the exhaust gas duct 2. Further, the waste heat recovery section 4 performs heat exchange between the exhaust gas from the outlet 12 and the heat exchanging medium and then returns the exhaust gas to the axial direction of the exhaust gas duct 2 to guide the exhaust gas to the inlet 14. The switching valve 31 cuts off a current passing through the exhaust gas duct 2 to guide the exhaust gas to the outlet 12. The waste heat recovery section 4 is arranged coaxially to the exhaust gas duct 2 and equipped with an outer case 6 covering the outside of the exhaust duct 2. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to an exhaust heat recovery device that is interposed in an exhaust passage from an internal combustion engine and recovers exhaust heat by exchanging heat between exhaust and a heat exchange medium.

2. Description of the Related Art Conventionally, as disclosed in Patent Document 1, there is known an apparatus that is interposed in an exhaust passage and performs heat exchange between exhaust from an internal combustion engine and a heat exchange medium such as cooling water of the internal combustion engine.
In this apparatus, the outer pipe of the muffler part and the cylindrical shell of the exhaust heat recovery part that covers the outer periphery of the outer pipe are coaxially arranged, and the exhaust heat recovery part is disposed between the inner periphery of the shell and the outer periphery of the outer pipe. Provided with a heat exchange chamber formed by a pair of provided partition plates, and provided with a small-diameter pipe that passes through the heat-exchange chamber through the pair of partition plates, distributes exhaust through the small-diameter pipe, and exchanges heat in the heat-exchange chamber The medium is distributed. The muffler portion includes an inner pipe through which the exhaust passes and an outer pipe that covers the outer side of the inner pipe, and the inner pipe has a large number of small holes communicating with the inner pipe. Further, a switching valve for switching the exhaust gas flowing between the muffler part and the exhaust heat recovery part is provided.
No. 2006-105124

  In such a conventional apparatus, a communication hole is formed on the upstream side of the switching valve, the exhaust of the exhaust gas to the muffler portion is blocked by the switching valve, and the exhaust is led from the communication hole to the exhaust heat recovery unit. Then, the exhaust gas that has passed through the exhaust heat recovery section is configured to flow into the exhaust flow path on the downstream side of the switching valve.

  However, even when the switching valve is switched so that the exhaust gas passes through the muffler part, the communication hole that introduces the exhaust gas to the upstream exhaust heat recovery part and the exhaust gas that has passed through the downstream exhaust heat recovery part are exhausted. A pressure difference is generated between the exhaust gas and the exhaust gas, and the exhaust gas also flows into the exhaust heat recovery unit. Therefore, there has been a problem that heat exchange is performed between the exhaust gas flowing into the exhaust heat recovery section and the heat exchange medium.

  For example, even when cooling water is used as a heat exchange medium and the internal combustion engine is operated under a high load condition and heat exchange is not desired between the cooling water and the exhaust, There was a problem that heat exchange was performed and the temperature of the cooling water would rise excessively.

  An object of the present invention is to provide an exhaust heat recovery apparatus that can switch the flow of exhaust gas with a simple structure.

In order to achieve this problem, the present invention has taken the following measures in order to solve the problem. That is,
An exhaust pipe that is interposed in an exhaust flow path from the internal combustion engine and guides exhaust from the upstream side to the downstream side, an exhaust heat recovery section that exchanges heat between the exhaust and the heat exchange medium, and the exhaust pipe In an exhaust heat recovery apparatus comprising a switching valve that shuts off and switches to a flow that passes through the exhaust heat recovery unit,
Provided with a outlet hole and the inlet hole opened in the radial direction on the outer circumference of the exhaust pipe, wherein the outlet hole and the inlet hole is provided in the vicinity of the axial direction of the exhaust pipe,
The exhaust heat recovery section includes an outer case that is arranged coaxially with the exhaust pipe and covers the outside of the exhaust pipe, and the exhaust gas that has flowed into the outer case from the outflow hole is on the inner peripheral side of the outer case Flowing in the axial direction of the exhaust pipe, performing heat exchange between the exhaust pipe and the outer case, and returning to the axial direction of the exhaust pipe in the opposite direction to the inflow, leading to the inflow hole,
The switching valve is an exhaust heat recovery device characterized in that the flow through the exhaust pipe is blocked and the exhaust is guided to the outflow hole.

In this case, a partition plate that blocks communication between the outflow hole and the inflow hole may be provided between the outer case and the exhaust pipe in the axial direction of the exhaust pipe. Alternatively, a guide member is provided between the outer case and the exhaust pipe to guide the exhaust from the outflow hole to the exhaust heat recovery unit and guide the exhaust from the exhaust heat recovery unit to the inflow hole. It is good also as a structure.

  The switching valve is a butterfly valve having a plate-like valve body supported so as to be swingable. An inflow pipe is inserted into the exhaust pipe from the radial direction toward the valve body, and the tip of the inflow pipe is inserted. The inflow hole may be formed by an opening, and the inflow hole may be arranged to be closed by swinging the valve body.

  In the exhaust heat recovery apparatus of the present invention, the outflow hole and the inflow hole are provided in the vicinity, and no pressure difference is generated between the outflow hole and the inflow hole, so that the outflow hole and the inflow hole are formed in the exhaust pipe. However, there is almost no exhaust flowing from the outflow hole to the inflow hole via the exhaust heat recovery part, and the heat flow can be exchanged between the exhaust and the heat exchange medium by switching the exhaust flow reliably with a simple structure. If the temperature of the heat exchange medium is excessively increased, unnecessary heat exchange between the exhaust gas and the heat exchange medium can be suppressed.

  Further, if the partition plate and the guide member are provided, it is possible to block the exhaust from directly passing from the outflow hole to the inflow hole. Furthermore, if an inflow pipe is provided and the inflow hole is closed with a valve body, it is possible to more reliably suppress the exhaust from flowing into the exhaust heat recovery section.

The best mode for carrying out the present invention will be described below in detail with reference to the drawings.
As shown in FIG. 1, reference numeral 1 denotes an exhaust heat recovery device according to this embodiment, which is interposed in an exhaust passage from an internal combustion engine (not shown). An exhaust pipe 2 covers the outside of the exhaust pipe 2 and an exhaust heat recovery unit 4 is disposed.

  The exhaust heat recovery unit 4 includes an outer case 6 that covers the outside of the exhaust pipe 2, and the outer case 6 is cylindrical and disposed coaxially with the exhaust pipe 2. Both ends of the outer case 6 are reduced in diameter to an outer diameter slightly larger than the outer diameter of the exhaust pipe 2 to form connecting portions 8 and 10. Both connecting portions 8 and 10 are formed on the same axis, and one of the connecting portions 8 is connected to an upstream exhaust passage from an internal combustion engine (not shown), and the other connecting portion 10 is connected to the downstream exhaust flow. Connected to the road.

  The outer periphery of one end of the exhaust pipe 2 is inserted and fixed to the inner periphery of the other connecting portion 10. The other end side of the exhaust pipe 2 extends to the vicinity of one connecting portion 8. On the outer periphery of the exhaust pipe 2, an outflow hole 12 and an inflow hole 14 that are opened in the radial direction are provided. In the present embodiment, the outflow hole 12 and the inflow hole 14 are provided at the same position on the same axis in the axial direction of the exhaust pipe 2 so as to face each other on the opposite side by 180 degrees.

  The outflow hole 12 and the inflow hole 14 are not limited to the same position, and need only be provided in the vicinity of the axial direction of the exhaust pipe 2, and are not limited to the opposite side of 180 degrees and are provided at a position of 90 degrees. May be. In the present embodiment, the outflow hole 12 and the inflow hole 14 are provided near the other connecting portion 10.

  A pair of ring-shaped meshes 16 and 18 are attached to the outer periphery of the exhaust pipe 2 upstream of the outflow hole 12 and the inflow hole 14 at a predetermined interval. An inner pipe 20 is further attached to the outside of the meshes 16 and 18. A ring-shaped cover plate 22 is attached and closed on one upstream connecting portion 8 side between the outer case 6 and the inner pipe 20.

  In addition, a heat exchanging unit 24 is provided between the outer case 6 and the inner pipe 20. For example, as shown in FIG. 3, the heat exchanging portion 24 penetrates the outer case 6 from the outside to the inside and bends along the axial direction of the exhaust pipe 2, and the outer case 6 from the outside to the inside. And a medium outflow pipe 28 bent along the axial direction of the exhaust pipe 2.

  The medium inflow pipe 26 and the medium outflow pipe 28 are communicated with each other by a large number of branch pipes 29 formed in a ring shape according to the inner peripheral shape of the outer case 6, and are connected to the medium inflow pipe 26 and the medium outflow pipe 28. The ring-shaped fins 30 are attached.

  The exhaust gas flowing into the heat exchanging section 24 flows in the axial direction of the exhaust pipe 2 from the medium outlet pipe 28 side to the upstream side of the exhaust gas along the inner peripheral side of the outer case 6, as indicated by arrows in FIG. It flows between the numerous fins 30 and flows to the medium inflow pipe 26 side on the opposite side by 180 degrees. At that time, the lid plate 22 restricts the further upstream flow along the axial direction of the exhaust pipe 2.

  The exhaust gas is formed so as to flow in the axial direction of the exhaust pipe 2 in the axial direction of the exhaust pipe 2 in the direction opposite to the inflow side along the inner peripheral side of the outer case 6. The exhaust flow is U-turned in the exhaust heat recovery unit 4 so that the flow toward the upstream side along the axial direction of the exhaust pipe 2 is returned to the flow toward the downstream side along the axial direction of the exhaust pipe 2. It is configured.

  As shown in FIG. 1, the exhaust pipe 2 is provided with a switching valve 31. The switching valve 31 is a butterfly valve having a plate-like valve body 32, and the valve body 32 is supported so as to be swingable. It is attached to the swing shaft 34. The valve body 32 is provided in the exhaust pipe 2, and in this embodiment, the swing shaft 34 is disposed so as to pass through the center in the axial direction of the exhaust pipe 2, and the center of the outflow hole 12 and the inflow hole 14. It is arranged at the position to tie.

  As shown by a solid line in FIG. 1, the valve body 32 swings the swing shaft 34, brings the valve body 32 into contact with the inner periphery of the exhaust pipe 2, and shuts the exhaust pipe 2. Is configured to be swingable between a position where the exhaust pipe 2 is communicated with the exhaust pipe 2 being substantially parallel to the axial direction of the exhaust pipe 2.

  When the exhaust pressure is high, the valve shaft 32 is parallel to the axial direction so that the exhaust pipe 2 communicates, and when the exhaust pressure is low, the swing shaft 34 is swinging to a position where the exhaust pipe 2 is shut off. The actuator may be configured to swing by a non-actuating actuator, or may be configured to swing and bias by a biasing member such as a spring at a position where the exhaust pipe 2 is blocked by the valve body 32.

  Further, the valve body 32 is disposed to face the outflow hole 12 and the inflow hole 14, and when the valve body 32 is swung to a position where the exhaust pipe 2 is shut off, The exhaust pipe 2 on the side and the outflow hole 12 are in communication with each other, and the exhaust pipe 2 on the downstream side and the inflow hole 14 are in communication with each other.

  Further, as shown in FIG. 2, between the outer periphery of the exhaust pipe 2 and the inner periphery of the outer case 6, the exhaust is prevented from flowing into the inflow hole 14 from the outflow hole 12 without passing through the heat exchange portion 24. A pair of partition plates 38 and 40 are provided.

Next, the operation of the exhaust heat recovery apparatus of the present embodiment described above will be described.
First, when the exhaust from the internal combustion engine flows into the one connecting portion 8 from the upstream exhaust passage, the exhaust flows in the exhaust pipe 2 downstream. When the exhaust pressure is low, the valve body 32 is oscillated to a position where the valve body 32 comes into contact with the inner periphery of the exhaust pipe 2 and shuts off the exhaust pipe 2 via the oscillation shaft 34.

  Thus, the exhaust from the upstream flows into the outer case 6 from the outflow hole 12 and flows into the heat exchange unit 24. The exhaust gas that has flowed into the heat exchanging section 24 flows upstream along the inner peripheral side of the outer case 6 in the axial direction of the exhaust pipe 2. Then, the air flows through a large number of fins 30, flows to the opposite side by 180 degrees, flows along the axial direction of the exhaust pipe 2, and flows downstream along the inner peripheral side of the outer case 6.

  The exhaust flow makes a U-turn in the exhaust heat recovery section 4 and flows toward the upstream side along the axial direction of the exhaust pipe 2 and then flows toward the downstream side along the axial direction of the exhaust pipe 2. , It returns from the inlet hole 14 into the exhaust pipe 2. Then, it flows out from the exhaust pipe 2 to the exhaust passage on the downstream side.

  While the exhaust gas flows through the heat exchanging section 24, heat exchange is performed with the heat exchange medium flowing from the medium inflow pipe 26 to the medium outflow pipe 28 via the multiple branch pipes 29. Thereby, the temperature of the exhaust gas decreases and the temperature of the heat exchange medium increases.

  On the other hand, when the pressure of the exhaust gas from the internal combustion engine is high, the valve body 32 is oscillated in parallel with the axial direction of the exhaust pipe 2 via the oscillating shaft 34, and the exhaust from the upstream flows into one connecting portion 8. When it flows in, it flows in the exhaust pipe 2 downstream, passes through the switching valve 31 and flows out from the other connecting portion 10 to the downstream exhaust flow path.

  When the exhaust gas flows through the exhaust pipe 2 to the downstream side, the exhaust gas passes through a portion where the outflow hole 12 and the inflow hole 14 are provided. Since the outflow hole 12 and the inflow hole 14 are provided in the vicinity, there is no pressure difference between the outflow hole 12 and the inflow hole 14. Therefore, even if the outflow hole 12 and the inflow hole 14 are formed in the exhaust pipe 2, there is almost no exhaust gas flowing from the outflow hole 12 to the inflow hole 14 via the heat exchange unit 24.

  Therefore, when the exhaust pressure is high and heat exchange between the exhaust and the heat exchange medium causes the temperature of the heat exchange medium to rise excessively, the valve body 32 is made parallel to the axial direction and the exhaust pipe Even if 2 is communicated, the exhaust does not flow into the heat exchanging section 24, so that unnecessary heat exchange between the exhaust and the heat exchange medium can be suppressed.

  In the above-described embodiment, the swing shaft 34 is arranged at the center of the exhaust pipe 2 in the axial direction. However, the present invention is not limited to this, and the swing shaft 34 is the axis of the exhaust pipe 2 as in the second embodiment shown in FIG. It can be similarly implemented even if it is arranged at a position eccentric from the center of the direction. The same members as those in the above-described embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. The same applies hereinafter.

  Further, as in the third embodiment shown in FIG. 5, instead of the inflow hole 14 formed in the exhaust pipe 2, an inflow pipe 50 orthogonal to the axial direction of the exhaust pipe 2 is inserted into the exhaust pipe 2, and the inflow An inflow hole 52 may be formed by opening the tip of the pipe 50, and the outer case 6 and the exhaust pipe 2 may be communicated with each other through the inflow pipe 50. At that time, the inflow hole 52 at the tip of the inflow pipe 50 in the exhaust pipe 2 is disposed so as to be closed by the valve body 32 when the valve body 32 is swung in parallel with the axial direction of the exhaust pipe 2.

  As a result, when exhaust pressure is high, when the exhaust pipe 2 is communicated with the valve body 32 parallel to the axial direction, the inflow hole 52 is closed by the valve body 32, and the heat exchange section 24 is more reliably exhausted. Can be prevented from flowing.

  Furthermore, as in the fourth embodiment shown in FIG. 6, when the swing shaft 34 is arranged at a position away from the axial center of the exhaust pipe 2, the length of the inflow pipe 50 is shortened, and the fifth You may comprise similarly to embodiment.

  Alternatively, as in the fifth embodiment shown in FIG. 7, instead of the partition plates 38 and 40 of the above-described embodiment, a cylindrical guide member 54 that guides exhaust gas from the outflow hole 12 to the heat exchange unit 24 is provided. A cylindrical guide member 56 that guides the exhaust gas from the heat exchange unit 24 to the inflow hole 14 may be provided.

  Moreover, it is good also as a structure which has arrange | positioned upstream and downstream symmetrically like embodiment mentioned above like 6th Embodiment shown in FIG. As shown in FIG. 8, the configuration can be similarly implemented by arranging the switching valve 31, the outflow hole 12, and the inflow hole 14 on the upstream side of the exhaust pipe 2, and disposing the heat exchange unit 24 on the downstream side of this. It is.

  The present invention is not limited to such embodiments as described above, and can be implemented in various modes without departing from the gist of the present invention.

It is a schematic structure figure showing the exhaust heat recovery device as one embodiment of the present invention in a section. It is AA sectional drawing of FIG. It is an expansion schematic block diagram which shows the heat exchange part of this embodiment in a cross section. It is a schematic block diagram which shows the exhaust heat recovery apparatus as 2nd Embodiment in a cross section. It is a schematic block diagram which shows the exhaust heat recovery apparatus as 3rd Embodiment in a cross section. It is a schematic block diagram which shows the exhaust heat recovery apparatus as 4th Embodiment in a cross section. It is a schematic block diagram which shows the exhaust heat recovery apparatus as 5th Embodiment in a cross section. It is a schematic block diagram which shows the exhaust heat recovery apparatus as 6th Embodiment in a cross section.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Exhaust heat recovery apparatus 2 ... Exhaust pipe 4 ... Exhaust heat recovery part 6 ... Outer case 8, 10 ... Connection part 12 ... Outflow hole 14, 52 ... Inflow hole 22 ... Cover plate 24 ... Heat exchange part 26 ... Medium inflow pipe 28 ... Medium outlet pipe 29 ... Branch pipe 30 ... Fin 31 ... Switching valve 32 ... Valve body 34 ... Oscillating shaft 38, 40 ... Partition plate 50 ... Inlet pipe 54, 56 ... Guide member

Claims (4)

An exhaust pipe that is interposed in an exhaust flow path from the internal combustion engine and guides exhaust from the upstream side to the downstream side, an exhaust heat recovery section that exchanges heat between the exhaust and the heat exchange medium, and the exhaust pipe In an exhaust heat recovery apparatus comprising a switching valve that shuts off and switches to a flow that passes through the exhaust heat recovery unit,
Provided with a outlet hole and the inlet hole opened in the radial direction on the outer circumference of the exhaust pipe, wherein the outlet hole and the inlet hole is provided in the vicinity of the axial direction of the exhaust pipe,
The exhaust heat recovery section includes an outer case that is arranged coaxially with the exhaust pipe and covers the outside of the exhaust pipe, and the exhaust gas that has flowed into the outer case from the outflow hole is on the inner peripheral side of the outer case Flowing in the axial direction of the exhaust pipe, performing heat exchange between the exhaust pipe and the outer case, and returning to the axial direction of the exhaust pipe in the opposite direction to the inflow, leading to the inflow hole,
In addition, the switching valve is configured to block the flow through the exhaust pipe and guide the exhaust to the outflow hole. 2. The exhaust according to claim 1 , wherein a partition plate that blocks communication between the outflow hole and the inflow hole is provided between the outer case and the exhaust pipe in an axial direction of the exhaust pipe. Heat recovery device. A guide member is provided between the outer case and the exhaust pipe to guide the exhaust from the outflow hole to the exhaust heat recovery part and guide the exhaust from the exhaust heat recovery part to the inflow hole. The exhaust heat recovery apparatus according to claim 1 , wherein The switching valve is a butterfly valve having a plate-like valve body supported so as to be swingable. An inflow pipe is inserted into the exhaust pipe from the radial direction toward the valve body, and is opened by a tip opening of the inflow pipe. The exhaust heat recovery device according to any one of claims 1 to 3 , wherein the inflow hole is formed, and the inflow hole is arranged to be closed by swinging the valve body.

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