JP6620764B2 - Exhaust heat recovery unit - Google Patents

Description

  The present invention relates to an exhaust heat recovery device.

  Patent Document 1 discloses an exhaust heat recovery device. In the exhaust heat recovery device of Patent Document 1, the rear end portion of the punching pipe is closed with a valve so that the exhaust gas inside the punching pipe flows to the outside in the radial direction of the punching pipe through the hole of the punching pipe. The heat of the exhaust gas is recovered at the heat exchange section on the outer side in the direction.

JP 2010-24907 A

  In the exhaust heat recovery device of Patent Document 1, the punching pipe is configured as, for example, an inner tube disposed inside the outer tube, and when the exhaust heat is not recovered, the rear end portion of the inner tube is opened. When the rear end of the inner pipe is opened, the exhaust gas inside the inner pipe flows to the rear of the vehicle through the rear end of the inner pipe, but a part of the exhaust gas inside the inner pipe is May flow to the radially outer side of the inner tube through the holes. When the exhaust gas flows into the radially outer side of the inner pipe, the heat of the exhaust gas is recovered at the heat exchange section on the radially outer side of the inner pipe.

  In view of the above facts, the present invention has an object to obtain an exhaust heat recovery device that can suppress the flow of exhaust gas from the inner pipe to the heat exchange section when the rear end of the inner pipe is open. It is.

  An exhaust heat recovery device according to claim 1 is disposed along an axial direction of the inner tube on an outer periphery of the inner tube and an inner tube that distributes exhaust gas from the engine to the vehicle rear side. An outer pipe extending from the end to the vehicle rear side, a valve for opening and closing a rear end of the inner pipe, and an inflow opening opening toward the vehicle rear side from the inside of the inner pipe A first throttle portion for flowing the exhaust gas flowing from the inside of the inner pipe through the inlet to the front side of the vehicle and guiding the exhaust gas to the radially outer side of the inner pipe through a hole formed in the inner pipe; A flow path formed between the inner pipe and the outer pipe and through which exhaust gas led to the radially outer side of the inner pipe through the hole is circulated to the vehicle rear side on the radially outer side of the inner pipe. The heat exchange between the exhaust gas that is disposed radially outside the inner pipe and flows through the flow path and the refrigerant Provided that a heat exchange portion, and a second throttle portion provided on the flow direction downstream side of the heat exchange section in the flow path.

  The throttle portion refers to a portion where the flow rate of the exhaust gas is increased by restricting the cross-sectional area of the flow channel to a predetermined range.

  According to the exhaust heat recovery device of the first aspect, the exhaust gas from the engine flows through the inner pipe to the vehicle rear side. When the rear end portion of the inner pipe is closed by the valve, the exhaust gas inside the inner pipe flows from the inside of the inner pipe into the first throttle portion through the inlet. The exhaust gas that has flowed into the first throttle part flows through the first throttle part toward the vehicle front side, and is guided to the radially outer side of the inner pipe through a hole formed in the inner pipe.

  The exhaust gas guided to the outer side in the radial direction of the inner pipe flows through the flow path formed between the inner pipe and the outer pipe to the vehicle rear side on the outer side in the radial direction of the inner pipe. The exhaust gas flowing through the flow path is heat exchanged with the refrigerant in the heat exchange unit. The exhaust gas heat-exchanged in the heat exchange part flows through the second throttle part.

  On the other hand, when the rear end of the inner pipe is opened by the valve, the exhaust gas inside the inner pipe extends through the rear end of the inner pipe to the rear side of the vehicle from the rear end of the inner pipe in the outer pipe. It flows into the part that was made. Further, a part of the exhaust gas inside the inner pipe tends to go to the heat exchange section through the first throttle part, the hole of the inner pipe and the flow path.

  Here, in the configuration of claim 1, not only the heat exchange part in the flow path but also the downstream part in the flow direction, the throttle part (first throttle part) not only in the introduction part that leads the exhaust gas to the flow path through the hole of the inner pipe. Is provided. In the throttle portion, the flow rate of the exhaust gas is increased by restricting the cross-sectional area of the flow path to a predetermined range. If the flow rate is high, the pressure drops according to Bernoulli's theorem. Therefore, by providing a throttle part (first throttle part) at the introduction part to the flow path, the pressure at the introduction part to the flow path and the flow path The difference with the pressure on the downstream side in the flow direction is smaller than the heat exchange part in

  Thereby, it is difficult for a part of the exhaust gas inside the inner pipe to flow into the heat exchange part through the first throttle part, the hole of the inner pipe and the flow path. Therefore, according to the structure of Claim 1, when the rear-end part of an inner pipe is open | released, it can suppress that exhaust gas flows in into a heat exchange part from an inner pipe.

  Since this invention set it as the said structure, when the rear-end part of an inner pipe is open | released, it has the outstanding effect that it can suppress that exhaust gas flows in into a heat exchange part from an inner pipe.

It is a sectional side view which shows the exhaust heat recovery device which concerns on this embodiment. FIG. 2 is a side sectional view showing a state in which the rear end portion of the inner pipe is closed by a valve in the exhaust heat recovery device shown in FIG. 1.

  Below, an example of an embodiment concerning the present invention is described based on a drawing. Note that an arrow RR and an arrow UP shown in each figure indicate the vehicle rear side and the vehicle upper side, respectively. Moreover, in the following description, the front-rear direction of the vehicle and the up-down direction of the vehicle may be simply expressed as front-rear and up-down, respectively. In the following description, the upstream side in the exhaust gas flow direction and the downstream side in the exhaust gas flow direction may be simply expressed as the upstream side and the downstream side, respectively.

(Exhaust heat recovery device 10)
First, the configuration of the exhaust heat recovery device 10 according to the present embodiment will be described. FIG. 1 is a side sectional view showing the exhaust heat recovery device 10.

  The exhaust heat recovery device 10 has a function of recovering heat of the exhaust gas by exchanging heat between a refrigerant such as water and the exhaust gas and reusing the heat. Specifically, the exhaust heat recovery device 10 includes an inner pipe 20, an outer pipe 30, a valve 40, a shield pipe 50, a first throttle part 51, a flow path 60, a heat exchange part 70, a separator. 80 and a second diaphragm 82. The specific configuration of each of these components will be described below.

(Inner pipe 20)
The inner pipe 20 is an example of an inner pipe that circulates exhaust gas from an engine of a vehicle (automobile) to the vehicle rear side. Specifically, the inner pipe 20 includes an upstream pipe 22 and a downstream pipe 24.

  The upstream side pipe 22 is a pipe that constitutes an upstream side portion (front side portion) of the inner pipe 20. Specifically, the upstream pipe 22 includes an upstream portion 22A, a downstream portion 22C, and a connecting portion 22B.

  The upstream portion 22A is connected to an exhaust pipe 102 disposed on the vehicle front side (upstream side) with respect to the exhaust heat recovery device 10. In the upstream portion 22A, a plurality of circular holes 22H (an example of holes) penetrating the upstream portion 22A in the radial direction (thickness direction) are formed. The plurality of circular holes 22H are arranged in a line along the circumferential direction of the upstream portion 22A.

  The downstream portion 22C is a portion disposed on the downstream side with respect to the upstream portion 22A. The downstream portion 22C has a smaller diameter than the upstream portion 22A.

  The connecting portion 22B is a portion that connects the downstream end of the upstream portion 22A and the upstream end of the downstream portion 22C. The connecting portion 22B is formed in a tapered shape that gradually decreases in diameter from the downstream end of the upstream portion 22A to the upstream end of the downstream portion 22C.

  The downstream pipe 24 is a pipe that forms a downstream portion of the inner pipe 20. The downstream pipe 24 is disposed on the downstream side with respect to the upstream pipe 22. Specifically, the downstream pipe 24 has an upstream portion 24A and a downstream portion 24C.

  In the upstream portion 24 </ b> A, the outer peripheral surface of the upstream end portion is joined to the inner peripheral surface of the downstream end portion of the downstream portion 22 </ b> C of the upstream pipe 22. The upstream portion 24A extends from the downstream end of the downstream portion 22C of the upstream pipe 22 to the vehicle rear side.

  The downstream portion 24C extends from the downstream end of the upstream portion 24A to the vehicle rear side. The downstream portion 24C is formed in a tapered shape that is gradually expanded in diameter toward the downstream side. The downstream portion 24 </ b> C constitutes the rear end portion of the inner pipe 20.

(Outer pipe 30)
The outer pipe 30 is an example of an outer pipe arranged along the axial direction of the inner pipe 20 on the outer periphery of the inner pipe 20. The outer pipe 30 extends to the vehicle rear side from the downstream portion 24C of the inner pipe 20. Specifically, the outer pipe 30 includes an upstream pipe 32, an intermediate pipe 33, and a downstream pipe 34.

  The upstream pipe 32 is a pipe that constitutes an upstream part of the outer pipe 30. The upstream pipe 32 has a reduced diameter at the upstream portion (front end side portion). This upstream portion is joined to the upstream portion 22 </ b> A of the upstream pipe 22 of the inner pipe 20.

  The downstream pipe 34 is a pipe that forms a downstream portion of the outer pipe 30. The downstream pipe 34 has a straight shape along the axial direction (vehicle longitudinal direction) of the inner pipe 20 at the lower portion 34B. The upper part 34A of the downstream pipe 34 is formed in a convex shape protruding upward. Thereby, the arrangement space which arrange | positions the valve | bulb 40 is ensured.

  Further, the downstream pipe 34 extends to the vehicle rear side from the rear end portion of the inner pipe 20. A downstream end (rear end) of the downstream pipe 34 is connected to an exhaust pipe 104 disposed on the vehicle rear side (downstream side) with respect to the exhaust heat recovery device 10.

  The intermediate pipe 33 is configured by a pipe having a constant diameter along the axial direction of the inner pipe 20 (rear side of the vehicle). The inner peripheral surface of the upstream end of the intermediate pipe 33 and the inner peripheral surface of the downstream end are joined to the outer peripheral surface of the downstream end of the upstream pipe 32 and the outer peripheral surface of the upstream end of the downstream pipe 34, respectively. Yes.

(Valve 40)
The valve 40 is a valve that opens and closes the downstream portion 24 </ b> C of the downstream pipe 24 in the inner pipe 20. Specifically, the valve 40 includes a valve body 42, a valve shaft 42, and a support member 44.

  The valve body 42 is formed in a substantially disk shape that is circular when viewed in the vehicle front-rear direction. The valve body 42 is gradually expanded in diameter toward the vehicle rear side. The valve body 42 is sized and shaped to fit inside the downstream portion 24C of the downstream pipe 24 in the inner pipe 20 and to close the opening of the downstream portion 24C.

  One end of the support member 44 is fixed to the back surface of the valve body 42 (the surface on the vehicle rear side when the valve body 42 is closed as shown in FIG. 2). The other end of the support member 44 is fixed to the outer periphery of the valve shaft 42. Thereby, the valve body 42 is supported by the valve shaft 42.

  The valve shaft 42 is disposed along the vehicle width direction between the downstream portion 24 </ b> C of the inner pipe 20 and the upper portion 34 </ b> A of the downstream pipe 34 of the outer pipe 30. The valve shaft 42 rotates between an open position (position shown in FIG. 1) where the valve body 42 opens the opening of the downstream portion 24C and a closed position (position shown in FIG. 2) which closes the opening of the downstream portion 24C. It is supposed to be. The valve shaft 42 is rotated between an open position and a closed position by a drive unit such as a thermoactuator.

(Shield pipe 50 and first throttle 51)
The shield pipe 50 is a pipe that is disposed on the inner side of the inner pipe 20 and forms the first throttle part 51 between the shield pipe 50 and the inner pipe 20. The shield pipe 50 has an upstream part 52, a downstream part 56, and a connecting part 54.

  The outer peripheral surface of the upstream portion 52 is joined to the inner peripheral surface of the upstream portion 22 </ b> A of the upstream pipe 22 of the inner pipe 20. Specifically, the outer peripheral surface of the upstream portion 52 is upstream (front side) from the circular hole 22H, and is downstream from the connection portion between the upstream portion 22A and the exhaust pipe 102 (rear side). It is joined to the inner peripheral surface of the portion 22A.

  The downstream portion 56 is a portion disposed on the downstream side with respect to the upstream portion 52. The downstream portion 56 has a smaller diameter than the upstream portion 52. Thereby, the outer peripheral surface of the downstream part 56 is opposed to the inner peripheral surface of the upstream part 22A with a gap. Specifically, the outer peripheral surface of the downstream portion 56 faces the inner peripheral surface of the upstream portion 22A on the downstream side (rear side) of the circular hole 22H.

  The connecting portion 54 is a portion that connects the downstream end of the upstream portion 52 and the upstream end of the downstream portion 56. The connecting portion 54 is formed in a tapered shape that gradually decreases in diameter from the downstream end of the upstream portion 52 to the upstream end of the downstream portion 56. Thereby, the outer peripheral surface of the connection part 54 is gradually separated from the inner peripheral surface of the upstream part 22A as it goes downstream. The outer peripheral surface of the connecting portion 54 faces the circular hole 22H.

  And the clearance gap between the outer peripheral surface of the connection part 54 and the outer peripheral surface of the downstream part 56, and the internal peripheral surface of 22 A of upstream parts is comprised as the 1st aperture | diaphragm | squeeze part 51. FIG. The first throttle 51 has an inlet 53 that opens toward the downstream side (rear side) with respect to the inside of the inner pipe 20. The inflow port 53 is formed between the downstream end of the downstream portion 56 of the shield pipe 50 and the downstream end of the upstream portion 22A of the upstream pipe 22 of the inner pipe 20. Exhaust gas flows into the first throttle 51 from the inner pipe 20 through the inlet 53.

  In the first throttle part 51, a flow path is formed from the inlet 53 to the upstream side (front side) of the inner pipe 20. Furthermore, the downstream end of the flow path of the first throttle portion 51 communicates with the circular hole 22H.

  Thereby, in the 1st aperture | diaphragm | squeeze part 51, the exhaust gas which flowed in through the inflow port 53 from the inside of the inner pipe 20 is distribute | circulated to the front side, The exhaust gas is guide | induced to the radial direction outer side of the inner pipe 20 through the circular hole 22H.

  In the first throttle part 51, the flow rate of the exhaust gas is increased by restricting the cross-sectional area of the flow path to a predetermined range. Note that at least the flow path width (the width along the radial direction of the shield pipe 50) of the first throttle part 51 is made smaller than the hole diameter of the circular hole 22H. Further, it is desirable that the flow rate of the exhaust gas is increased by making the flow path cross-sectional area narrower than the upstream and downstream sides of the first throttle part 51 (the internal flow path of the inner pipe 20 and the circular hole 22H). .

(Flow path 60)
The flow path 60 is a flow path formed between the inner pipe 20 and the outer pipe 30. The flow path 60 distributes the exhaust gas guided from the first throttle part 51 to the radially outer side of the inner pipe 20 through the circular hole 22H to the vehicle rear side on the radially outer side of the inner pipe 20. The exhaust gas flowing through the flow path 60 flows into the exhaust pipe 104 through the inside of the extending portion 37 that extends to the vehicle rear side of the downstream portion 22C of the inner pipe 20 in the outer pipe 30.

(Heat exchange part 70)
The heat exchanging unit 70 is disposed outside the inner pipe 20 in the radial direction, and is a heat exchanging unit that exchanges heat between the exhaust gas flowing through the flow path 60 and the refrigerant. As an example, engine coolant is used as the refrigerant. Specifically, the heat exchange unit 70 includes a plurality of fins 72, a water channel forming pipe 74, and a heat insulating material 76.

  Each fin 72 is formed in a plate shape in which the circumferential direction of the inner pipe 20 is the thickness direction. The plurality of fins 72 are arranged at intervals along the circumferential direction of the inner pipe 20. Exhaust gas flowing through the flow path 60 passes between the plurality of fins 72.

  The heat insulating material 76 is formed in a cylindrical shape from a material having heat insulating properties, and is disposed coaxially with the inner pipe 20. Examples of the material for the heat insulating material 76 include, but are not limited to, mullite and interlam (trade name of 3M).

  The water channel forming pipe 74 is a pipe for forming a water channel 75 through which engine cooling water as a refrigerant flows. The water channel forming pipe 74 is reduced in diameter at the front end portion and the rear end portion and joined to the outer peripheral surface of the intermediate pipe 33. Thereby, a water channel 75 is formed between the inner peripheral surface of the intermediate portion in the axial direction of the water channel forming pipe 74 and the outer peripheral surface of the intermediate pipe 33. The water channel forming pipe 74 is formed with an inflow port (not shown) through which cooling water flows into the water channel 75 and an outflow port (not shown) through which cooling water flows out of the water channel 75. In addition, in this embodiment, although the water channel formation pipe 74 is comprised by two parts, you may be comprised by one part.

  In the heat exchanging unit 70, the heat of the exhaust gas flowing through the flow path 60 is transmitted to the cooling water flowing through the water channel 75 through the plurality of fins 72 and the intermediate pipe 33. Thereby, heat exchange is performed between the exhaust gas flowing through the flow path 60 and the cooling water. The intermediate pipe 33 described above can be understood as constituting a part of the heat exchange unit 70.

(Separator 80 and second throttle 82)
The separator 80 is a pipe that is disposed radially outside the inner pipe 20 and inside the outer pipe 30, and forms the second throttle portion 82 in the flow path 60.

  The separator 80 has a cylindrical portion 85 and a flange portion 83. The cylindrical portion 85 is formed in a cylindrical shape, and the inner peripheral surface is joined to the outer peripheral surface of the downstream portion 22 </ b> C of the upstream pipe 22 in the inner pipe 20.

  The flange portion 83 projects from the front end portion of the cylindrical portion 85 to the outside in the radial direction of the cylindrical portion 85. A second throttle portion 82 is formed between the outer peripheral end portion of the flange portion 83 and the downstream pipe 34 of the outer pipe 30. In the second throttle portion 82, the flow rate of the exhaust gas is increased by restricting the cross-sectional area of the flow path to a predetermined range. Specifically, the flow rate of the exhaust gas is increased in the second throttle portion 82 by making the channel cross-sectional area narrower than before and after (upstream and downstream sides) of the second throttle portion 82 in the channel 60. Yes.

(Operational effect of this embodiment)
Next, the function and effect of this embodiment will be described.

  According to the exhaust heat recovery device 10 according to the present embodiment, the exhaust gas from the engine flows through the inner pipe 20 to the vehicle rear side. As shown in FIG. 2, when the downstream portion 24 </ b> C of the downstream pipe 24 in the inner pipe 20 is closed by the valve 40, the exhaust gas inside the inner pipe 20 passes through the inlet 53 from the inside of the inner pipe 20. It flows into the first throttle part 51. The exhaust gas that has flowed into the first throttle portion 51 flows through the first throttle portion 51 toward the vehicle front side, and is guided to the radially outer side of the inner pipe 20 through the circular hole 22H of the inner pipe 20.

  The exhaust gas guided to the radially outer side of the inner pipe 20 flows through the flow path 60 formed between the inner pipe 20 and the outer pipe 30 to the vehicle rear side. The exhaust gas flowing through the flow path 60 is heat-exchanged with the cooling water flowing through the water channel 75 in the heat exchanging unit 70. The exhaust gas heat-exchanged in the heat exchange part 70 flows through the second throttle part 82 and flows into the exhaust pipe 104 from the flow path 60 through the inside of the extension part 37 of the outer pipe 30.

  On the other hand, as shown in FIG. 1, when the downstream portion 24 </ b> C of the downstream pipe 24 in the inner pipe 20 is opened by the valve 40, the exhaust gas inside the inner pipe 20 flows into the downstream portion 24 </ b> C of the downstream pipe 24. To the exhaust pipe 104 through the inside of the extending portion 37 of the outer pipe 30.

  Further, a part of the exhaust gas inside the inner pipe 20 tends to go to the heat exchanging unit 70 through the first throttle portion 51, the circular hole 22 </ b> H, and the flow path 60.

  Here, in the configuration of the present embodiment, not only the heat exchange part 70 in the flow path 60 on the downstream side in the flow direction but also the introduction part that leads the exhaust gas to the flow path 60 through the circular hole 22H (first restriction). Part 51). In the throttle portion, the flow rate of the exhaust gas is increased by restricting the cross-sectional area of the flow path to a predetermined range. When the flow velocity is high, the pressure decreases according to Bernoulli's theorem. Therefore, by providing a throttle part (first throttle part 51) at the introduction part to the flow path 60, the pressure at the introduction part to the flow path 60 can be reduced. In addition, the difference from the pressure on the downstream side in the flow direction with respect to the heat exchange unit 70 in the flow path 60 becomes smaller.

  Thereby, a part of the exhaust gas inside the inner pipe 20 does not flow into the heat exchanging part 70 through the first throttle part 51, the circular hole 22 </ b> H and the flow path 60. Therefore, according to the configuration of the present embodiment, it is possible to suppress the exhaust gas from flowing from the inner pipe 20 to the heat exchange unit 70 when the downstream portion 24C of the downstream pipe 24 in the inner pipe 20 is opened. As a result, when the heat recovery of the exhaust gas is not desired, the recovery of the heat of the exhaust gas is suppressed.

  The present invention is not limited to the above-described embodiment, and various modifications, changes, and improvements can be made without departing from the spirit of the present invention.

10 Exhaust heat recovery device 20 Inner pipe (example of inner pipe)
22H circular hole (example of hole)
24C downstream part (example of rear end part)
30 Outer pipe (an example of an outer pipe)
40 Valve 51 First throttle part 53 Inlet 60 Channel 70 Heat exchange part 82 Second throttle part

Claims (1)

An inner pipe for distributing exhaust gas from the engine to the rear side of the vehicle,
An outer pipe disposed on the outer circumference of the inner pipe along the axial direction of the inner pipe and extending to the vehicle rear side from the rear end of the inner pipe;
A valve for opening and closing the rear end of the inner pipe;
An inflow opening that opens toward the rear side of the vehicle with respect to the inside of the inner pipe, exhaust gas flowing from the inside of the inner pipe through the inflow opening is circulated to the front side of the vehicle, and the exhaust gas is A first throttle portion that leads to the radially outer side of the inner tube through a hole formed in the tube;
A flow path formed between the inner pipe and the outer pipe and through which exhaust gas guided to the radially outer side of the inner pipe through the hole is circulated to the vehicle rear side on the radially outer side of the inner pipe;
A heat exchanging part that is arranged on the radially outer side of the inner pipe and exchanges heat between the exhaust gas flowing through the flow path and the refrigerant;
A second throttle part provided downstream in the flow direction from the heat exchange part in the flow path;
Exhaust heat recovery device.