JP5088751B2 - Waste heat recovery unit - Google Patents

Description

  The present invention relates to an exhaust heat recovery device that warms cooling water with the heat of exhaust gas.

  When the driving source of the vehicle is an internal combustion engine, exhaust gas is generated from the internal combustion engine. The cooling water is warmed by heat exchange with the heat held by the exhaust gas, and the vehicle interior is warmed by the heat of the warmed cooling water (see, for example, FIG. 3 of Patent Document 1).

As shown in FIG. 7, when the temperature of the cooling water is equal to or lower than the predetermined temperature, the exhaust heat recovery device 100 has the bypass 102 closed by the temperature sensing valve 103, so that the exhaust gas is indicated by the arrow (2). Passes through the heat recovery chamber 104 as shown.
At this time, the cooling water flowing in the water jacket 105 is heated by the heat of the exhaust gas.
On the other hand, when the temperature of the cooling water is higher than a predetermined temperature, the temperature sensing valve 103 rotates clockwise to block the flow to the heat recovery chamber 104. As a result, the exhaust gas passes through the detour 102 as indicated by the arrow (3).

  By the way, the flow rate of the exhaust gas always changes according to the traveling state of the vehicle. That is, a large amount of exhaust gas may flow toward the heat recovery chamber 104. A water jacket 105 is disposed in the heat recovery chamber 104, and the exhaust gas passage is narrowed by the water jacket 105. For this reason, a large amount of exhaust gas flows toward the heat recovery chamber 104, thereby preventing smooth exhaust. This affects the output of the engine.

  It is desired to provide an exhaust heat recovery device that can perform exhaust smoothly while maintaining the output of the engine.

JP 2008-157211 A

  An object of the present invention is to provide an exhaust heat recovery device that can perform exhaust smoothly.

According to a first aspect of the present invention, there is provided a heat recovery chamber that allows exhaust gas generated by an engine to pass therethrough and warms the cooling water with the heat of the exhaust gas, and is disposed upstream of the heat recovery chamber and has a predetermined temperature of the cooling water. A temperature-sensitive valve that closes the inlet of the heat recovery chamber when the temperature is higher than the temperature, and a first valve that is arranged to bypass the heat recovery chamber and that allows the exhaust gas to flow when the temperature of the cooling water is higher than a predetermined temperature. In the exhaust heat recovery device having a detour,
The exhaust heat recovery device, together with said first bypass path provided separately from the second bypass passage for bypassing the heat recovery chamber, when the exhaust pressure of the exhaust gas definitive to the second bypass passage is higher than the predetermined pressure And an exhaust pressure valve that opens the second bypass ,
The cross-sectional area of the first detour is smaller than the cross-sectional area of the second detour,
The heat recovery chamber and the second bypass route divide the cylinder into a first chamber and a second chamber with a partition wall, the first chamber is a heat recovery chamber, and the second chamber is a bypass route,
The second bypass is formed integrally with the cylinder, and the first bypass is formed separately from the cylinder .

The invention according to claim 2 is characterized in that the first detour is located above the second detour .

  The invention according to claim 1 is provided with a second bypass and an exhaust pressure valve that opens the second bypass when the exhaust gas exhaust pressure is higher than a predetermined pressure. When the exhaust pressure of the exhaust gas is higher than a predetermined pressure, the exhaust pressure valve is opened and the exhaust gas flows through the second bypass. Even when the flow rate of the exhaust gas is increased and the exhaust pressure of the exhaust gas is high, a large amount of exhaust gas can be flowed using the second bypass. That is, it can be said that the exhaust heat recovery unit can smoothly flow a large amount of exhaust gas.

In addition, in the invention according to claim 1 , the cross-sectional area of the first detour is smaller than the cross-sectional area of the second detour. The first detour may be smaller than the second detour in which the exhaust gas flows when the flow rate of the exhaust gas is large. On the other hand, by reducing the cross-sectional area of the first detour, the exhaust heat recovery device can be made compact, and in addition, the noise can be reduced.

Furthermore, the size of the silencer connected to the downstream side of the exhaust heat recovery device can be reduced by reducing the noise. The manufacturing cost can be reduced by reducing the silencer.
In addition, the heat recovery chamber and the second bypass are integrally formed on the cylinder. Thereby, the heat recovery chamber and the second bypass can be made compact, and the exhaust heat recovery device as a whole becomes compact.

It is sectional drawing of the waste heat recovery device which concerns on this invention. FIG. 2 is a sectional view taken along line 2-2 of FIG. It is a figure explaining the temperature sensitive type valve concerning the present invention. It is a figure explaining the exhaust pressure valve concerning the present invention. It is a figure explaining the effect | action of the waste heat recovery device which concerns on this invention. It is a figure explaining the relationship between a sound pressure and rotation speed. It is a figure explaining the basic composition of the conventional technology.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. The drawings are viewed in the direction of the reference numerals.

  As shown in FIG. 1, the exhaust heat recovery device 10 includes a cylindrical body 13 in which an inlet 11 and an outlet 12 are formed in a throttle shape, a partition wall 15 that partitions the cylindrical body 13 up and down, and a partition wall 15. The first chamber 16 above the partition wall 15 to be partitioned, the second chamber 17 below the partition wall 15, and the partition wall 15 are arranged so that the exhaust gas can pass from the second chamber 17 toward the first chamber 16. And a first bypass 21 extending from above the hole 19 to the outlet 12.

  The first chamber 16 is provided with a heat recovery chamber 23 that allows exhaust gas to pass through and heats the cooling water with the heat of the exhaust gas, and is disposed upstream of the heat recovery chamber 23 (on the left side in the drawing). A temperature-sensitive valve 25 that closes the inlet 24 of the heat recovery chamber when the temperature is higher, and a lid body 26 that is disposed on the left side of the temperature-sensitive valve 25 and serves as a lid are disposed. That is, the first chamber 16 is formed in a bottomed cylindrical shape.

  The first bypass 21 is arranged so as to bypass the heat recovery chamber 23, and the exhaust gas flows when the temperature of the cooling water is higher than a predetermined temperature.

  In the second chamber 17, a second bypass route 28 that bypasses the heat recovery chamber 23 separately from the first bypass route 21, and an exhaust pressure of the exhaust gas that is disposed on the inlet side of the second bypass route 28 is a predetermined pressure. An exhaust pressure valve 29 is provided that opens when higher.

  In the heat recovery chamber 23, a plurality of gas passages 31 through which exhaust gas passes and a plurality of cooling water passages 32 that are arranged between the gas passages 31 and through which cooling water passes are alternately arranged. A cooling water inlet 33 extending toward the back of the drawing in order to take cooling water into these cooling water passages 32, and a cooling water outlet 34 from which the cooling water taken in and warmed from the cooling water inlet 33 is discharged. Connected. That is, a water jacket is arranged in the heat recovery chamber 23.

As shown in FIG. 2, fins 35 are arranged in the gas flow path 31 in order to efficiently perform heat exchange.
The cylindrical body 13 was partitioned into two chambers 16 and 17 by a partition wall 15, a heat recovery chamber 23 was provided in the first chamber 16, and a second bypass circuit 28 was provided in the second chamber 17. The heat recovery chamber 23 and the second bypass circuit 28 are formed integrally with the cylindrical body 13. As a result, the heat recovery chamber 23 and the second bypass 28 can be made compact, and the exhaust heat recovery device 10 as a whole becomes compact.

  The cross-sectional area of the first detour 21 is smaller than the cross-sectional area of the second detour 28. The first bypass 21 may be smaller than the second bypass 28 through which the exhaust gas flows when the flow rate of the exhaust gas is large. On the other hand, by reducing the cross-sectional area of the first detour 21, the exhaust heat recovery device 10 can be made compact, and in addition, clouding noise can be reduced.

Furthermore, the size of the silencer connected to the downstream side of the exhaust heat recovery device 10 can be reduced by reducing the noise. The manufacturing cost can be reduced by reducing the silencer.
The temperature sensitive valve will be described with reference to the next figure.

  As shown in FIG. 3, the temperature sensitive valve 25 includes a thermo wax part 36 in which wax that is melted as the temperature rises is built in, and an expansion / contraction of the thermo wax part 36 that is disposed at the tip of the thermo wax part 36. The rod 37 is moved in the horizontal direction of the drawing, the return spring 38 for applying a force against the thermowax 36 across the rod 37, and the thermowax 36 is housed and the cooling water is taken in from the water sampling port 39. The case 42 includes a case 42 for discharging cooling water from the discharge port 41, a lever 44 connected to the tip of the rod 37, and a flow path switching damper 45 that is rotated by the lever 44 and switches the flow path.

  When the temperature of the cooling water flowing through the case 42 rises, the thermowax 36 extends toward the right side of the drawing against the force of the return spring 38. As a result, the rod 37 is moved rightward as indicated by an imaginary line, and the lever 44 is rotated clockwise about the shaft 46. Thereby, the flow path switching damper 45 supported by the same shaft 46 is also rotated and turned downward. When the flow path switching damper 45 faces downward, the inlet (reference numeral 24 in FIG. 1) of the heat recovery chamber is closed.

  On the other hand, when the temperature of the cooling water becomes equal to or lower than the predetermined temperature, the return spring 38 extends toward the left side of the drawing against the force of the thermowax portion 36. As a result, the rod 37 and the link 43 are moved leftward, and the lever 44 is rotated counterclockwise about the shaft 46. Thereby, the flow path switching damper 45 is also rotated counterclockwise. When the flow path switching damper 45 faces in the horizontal direction, the first bypass (reference numeral 21 in FIG. 1) is closed.

When it is desired to change the predetermined temperature at which the temperature sensitive valve is operated, it is sufficient to replace it with a different type of thermo wax.
As the temperature-sensitive valve, various valves such as an electrically operated valve using a sensor and an actuator can be used in addition to a mechanically operated valve such as a thermo wax, a shape memory alloy spring or a diaphragm.

When a mechanically operated valve is used, an expensive part such as a sensor or an actuator is unnecessary, so that the exhaust heat recovery device can be manufactured at a low cost.
Next, the exhaust pressure valve will be described.

  As shown in FIG. 4A, the exhaust pressure valve 29 includes an open / close damper 48 that opens and closes the second bypass 28, a rotation shaft 49 that rotatably supports the open / close damper 48, and this rotation. The torsion spring 51 is arranged around the shaft 49 and biases the opening / closing damper 48 in a direction to close the second bypass 28.

  As shown in (b), when the flow rate of the exhaust gas is large, the exhaust pressure becomes higher than a predetermined pressure. In such a case, the pressure of the exhaust gas turns the open / close damper 48 counterclockwise against the force of the torsion spring 51. As a result, the exhaust gas having a high exhaust pressure passes through the second bypass 28.

On the other hand, when the flow rate of the exhaust gas decreases and the exhaust pressure becomes a predetermined pressure or lower, the second bypass 28 is closed by the force of the torsion spring 51 as shown in FIG.
When changing the predetermined pressure at which the exhaust pressure valve operates, a different type of torsion spring may be replaced.
The operation of the exhaust heat recovery path according to the present invention will be described with reference to the next figure.

  As shown in FIG. 5A, when the exhaust pressure is high and the coolant temperature is low, the exhaust pressure valve 29 is opened and the temperature sensitive valve 25 closes the first bypass 21. The exhaust gas passes through the heat recovery chamber 23 and heats the cooling water by heat exchange. However, since the flow rate is high at high loads, the exhaust gas passes through the second detour 28 in order to suppress the influence on the engine performance. The influence of is reduced.

  When the exhaust pressure of the exhaust gas is higher than a predetermined pressure, the exhaust pressure valve 29 is opened and the exhaust gas flows through the second bypass 28. Even when the flow rate of the exhaust gas is increased and the exhaust pressure of the exhaust gas is high, a large amount of exhaust gas can be caused to flow using the second bypass circuit 28. That is, it can be said that the exhaust heat recovery unit can smoothly flow a large amount of exhaust gas.

  When the exhaust pressure is high and the coolant temperature is high as shown in (b), the exhaust pressure valve 29 is opened, and the temperature sensitive valve 25 closes the heat recovery chamber 23. Most of the exhaust gas passes through the second bypass route 28, and the remaining part of the exhaust gas passes through the first bypass route 21.

As shown in (c), when the exhaust pressure is low and the coolant temperature is low, the exhaust pressure valve 29 is closed, and the temperature sensitive valve 25 closes the first bypass 21. The exhaust gas passes through the heat recovery chamber 23 and warms the cooling water by heat exchange.
At this time, the exhaust gas does not flow through the second bypass 28. When the exhaust gas flow rate is small, the exhaust gas can be passed sufficiently smoothly even if the exhaust gas does not flow through the second bypass 28.

  When the exhaust pressure is low and the cooling water temperature is high as shown in (d), the exhaust pressure valve 29 is closed, and the temperature sensitive valve 25 closes the heat recovery chamber 23. The exhaust gas passes through the first bypass 21.

  As shown in FIG. 6, the vertical axis represents the sound pressure of the noise, and the horizontal axis represents the number of rotations (rpm). Experiments were conducted by flowing exhaust gas through channels with different cross-sectional areas. The result of the channel having a small cross-sectional area is indicated by a line 53, and the result of the channel having a large cross-sectional area is indicated by a line 54.

  For both the line 53 and the line 54, the peak sound pressure was generated around 1200 (rpm), and then the sound pressure decreased to around 2500 (rpm). The sound pressure gradually increased after exceeding 2500 (rpm). During this time, line 53 is consistently below line 54, indicating that the sound pressure was low. That is, it can be said that the line 53 having a smaller cross-sectional area has a lower volume noise throughout.

  From this, it can be said that it is desirable to reduce the cross-sectional area of the first detour, which is known in advance that the flow rate of the exhaust gas is small, from the viewpoint of the generation of cloudy noise. Specifically, it is advisable to make it smaller than at least the second detour with a large exhaust gas flow rate. By reducing the cross-sectional area of the first detour, it is possible to reduce the occurrence of fogging noise. By reducing the fogging noise, the size of the silencer connected to the downstream side of the exhaust heat recovery device can be reduced. The manufacturing cost can be reduced by reducing the silencer.

  The use of the exhaust heat recovery device according to the present invention is not limited as long as it uses the exhaust heat of the exhaust gas by operating the engine, such as a transportation device such as a vehicle, or a cogeneration system.

  The exhaust heat recovery device of the present invention is suitable for a vehicle heating device.

  DESCRIPTION OF SYMBOLS 10 ... Waste heat recovery device, 13 ... Cylindrical body, 15 ... Partition wall, 16 ... 1st chamber, 17 ... 2nd chamber, 21 ... 1st detour, 23 ... Heat recovery chamber, 24 ... Entrance of heat recovery chamber, 25 ... temperature sensitive valve, 28 ... second bypass, 29 ... exhaust pressure valve.

Claims (2)

A heat recovery chamber that passes exhaust gas generated by the engine and heats the cooling water with the heat of the exhaust gas, and is disposed on the upstream side of the heat recovery chamber, and when the temperature of the cooling water is higher than a predetermined temperature, the heat recovery chamber Waste heat recovery having a temperature sensitive valve that closes the inlet of the chamber and a first bypass that is arranged to bypass the heat recovery chamber and that allows exhaust gas to flow when the temperature of the cooling water is higher than a predetermined temperature In the vessel
The exhaust heat recovery device, together with said first bypass path provided separately from the second bypass passage for bypassing the heat recovery chamber, when the exhaust pressure of the exhaust gas definitive to the second bypass passage is higher than the predetermined pressure And an exhaust pressure valve that opens the second bypass ,
The cross-sectional area of the first detour is smaller than the cross-sectional area of the second detour,
The heat recovery chamber and the second bypass route divide the cylinder into a first chamber and a second chamber with a partition wall, the first chamber is a heat recovery chamber, and the second chamber is a bypass route,
The second detour is formed integrally with the cylinder, and the first detour is formed separately from the cylinder . The exhaust heat recovery device according to claim 1, wherein the first detour is located above the second detour .

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