JP2018200020A - Engine catalyst cooling device - Google Patents

Abstract

To provide a catalyst cooling device capable of keeping a temperature of an exhaust emission control catalyst disposed in an exhaust passage in a low state with simple constitution.SOLUTION: An engine catalyst cooling device comprises: an exhaust emission control catalyst 6 including an inner cylinder 62 covering and holding a catalyst carrier 61, and an outer cylinder 63 covering the inner cylinder 62 while forming a clearance 6a between the inner cylinder and the outer cylinder; a first bypass passage 31 for taking out a part of an exhaust gas from an exhaust passage 3 at a downstream side of the exhaust emission control catalyst and supplying the exhaust gas to a vaporizer 9; a condensate storage portion 93 for storing condensate generated when the exhaust gas is supplied to the vaporizer; a communication passage 94 for supplying the condensate stored in the condensate storage portion to the clearance 6a of the exhaust emission control catalyst; a switching valve 96 disposed in the communication passage and opening and closing the communication passage between the condensate storage portion and the clearance according to a temperature of the exhaust emission control catalyst; a condensate return passage 64 for discharging the condensate passing through the clearance to the exhaust passage at the downstream side of the exhaust emission control catalyst; and a second bypass passage 95 for discharging the condensate to the exhaust passage without passing through the clearance from the condensate storage portion.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a catalyst cooling device that cools an exhaust purification catalyst disposed in an exhaust passage of an engine.

  Conventionally, gas engines using fuel gas such as liquefied petroleum gas (hereinafter referred to as “LPG”), natural gas (hereinafter referred to as “CNG”), and city gas are known (for example, Patent Documents 1 to 3). See).

  As described in Patent Document 2, since LPG is liquefied at a relatively low pressure at room temperature, it can be easily stored in a fuel container and mounted on a vehicle, and the basic structure is large compared to a gasoline engine. Since there is no difference, it is widely used as a fuel for vehicle engines. In an engine using LPG as a fuel, a vaporizer (vaporizer) for vaporizing liquid fuel is provided on a fuel supply path for supplying fuel from a fuel container stored in liquid to a fuel supply unit disposed in the engine. It is common practice to supply fuel gas that is disposed and vaporized to the engine.

Further, as described in Patent Document 3, when CNG or city gas is used for a gas engine, gas fuel is filled in a fuel gas cylinder as a fuel container in a compressed state and supplied to the engine. In a high pressure state, for example, 200 kgf / cm ² gas fuel filled in the fuel gas cylinder is decompressed to 3.5 kgf / cm ² by a regulator and supplied to the engine.

JP 2011-127544 A JP 2001-173520 A JP 2000-073870 A

  The general-purpose gas engine described above has a higher exhaust temperature than other internal combustion engines (gasoline engines), and the exhaust purification catalyst disposed in the exhaust passage tends to be hot. Therefore, it is desired to suppress the temperature from exceeding a predetermined temperature.

  The present invention has been made in view of the above-mentioned fact, and the main technical problem thereof is that the temperature of the exhaust purification catalyst disposed in the exhaust passage with a simple configuration is lower than the temperature at which thermal degradation is a concern. The object is to provide a catalyst cooling device that can be maintained.

  In order to solve the main technical problem, according to the present invention, there is provided a catalyst cooling device for cooling an exhaust purification catalyst of an engine, the engine storing an exhaust purification catalyst disposed in an exhaust passage and fuel. At least a fuel container, a fuel supply passage for supplying fuel from the fuel container to the engine, and a vaporizer disposed on the fuel supply passage. The catalyst cooling device covers and holds the catalyst carrier. An exhaust purification catalyst configured to include a cylinder and an outer cylinder that covers the inner cylinder so as to form a gap, and a part of the exhaust gas is extracted from an exhaust passage downstream of the exhaust purification catalyst. A first bypass passage for supplying exhaust gas to the vaporizer, a condensed water storage section for storing condensed water generated by supplying exhaust gas to the vaporizer, and the condensed water stored in the condensed water storage section The exhaust A communication path that supplies the clearance of the catalyst, a switching valve that is disposed in the communication path and that opens and closes the communication between the condensed water reservoir and the clearance according to the temperature of the exhaust purification catalyst, and the clearance A condensed water return passage that discharges the condensed water that has passed through the exhaust gas to an exhaust passage downstream of the exhaust purification catalyst, and a second bypass that discharges the condensed water from the condensed water reservoir to the exhaust passage without passing through the gap And a catalyst cooling device including at least a passage.

  According to the present invention, there is also provided a catalyst cooling device for cooling an exhaust purification catalyst of an engine, the engine comprising an exhaust purification catalyst disposed in an exhaust passage, a fuel container for storing fuel, and the fuel container At least a fuel supply passage for supplying fuel to the engine and a regulator disposed on the fuel supply passage, and the catalyst cooling device includes an inner cylinder that covers and holds the catalyst carrier, An exhaust purification catalyst that includes an outer cylinder that covers the gap so as to form a gap between the exhaust purification catalyst and a part of the exhaust gas that is extracted from an exhaust passage downstream of the exhaust purification catalyst and supplies the exhaust gas to the regulator A first bypass passage, a condensed water storage section for storing condensed water generated by supplying exhaust gas to the regulator, and the condensed water stored in the condensed water storage section Ream supplied to gap A switching valve that is disposed in the communication path and opens and shuts off the communication between the condensed water storage portion and the gap according to the temperature of the exhaust purification catalyst, and the condensed water that has passed through the gap is exhausted to the exhaust gas. Catalyst cooling comprising at least a condensed water return passage for discharging to the exhaust passage downstream of the purification catalyst, and a second bypass passage for discharging condensed water from the condensed water reservoir to the exhaust passage without passing through the gap An apparatus is provided.

  The switching valve is provided with a thermostat that operates according to the temperature of the exhaust purification catalyst, and shuts off the communication path when the temperature of the exhaust purification catalyst is lower than a predetermined temperature, and opens the communication path when the temperature is higher than the predetermined temperature. Preferably, the switching valve is operated. Further, it is preferable that the condensate storage part is installed above the exhaust purification catalyst, and the communication path is communicated with the upper part of the exhaust purification catalyst. Further, a muffler is disposed in the exhaust passage on the downstream side of the exhaust purification catalyst, and an exhaust extraction portion of the first bypass passage is provided in the exhaust passage between the exhaust purification catalyst and the muffler. It is preferable that a discharge portion to the exhaust passage of the bypass passage is provided on the downstream side of the muffler.

  The catalyst cooling device of the present invention includes an exhaust purification catalyst that includes an inner cylinder that covers and holds the catalyst carrier, and an outer cylinder that covers the catalyst carrier so as to form a gap between the inner cylinder and the exhaust purification catalyst. A first bypass passage for extracting a part of the exhaust gas from the downstream exhaust passage and supplying the exhaust gas to the vaporizer or regulator, and condensed water generated by supplying the exhaust gas to the vaporizer or regulator A condensate storage part for storing, a communication path for supplying the condensate stored in the condensate storage part to the gap of the exhaust purification catalyst, and a condensate storage part and the gap disposed in the communication path. A switching valve that opens and closes the communication according to the temperature of the exhaust purification catalyst, a condensed water return passage that discharges the condensed water that has passed through the gap to an exhaust passage downstream of the exhaust purification catalyst, and the condensation Do not pass through the gap from the water reservoir. And at least a second bypass passage for discharging water to the exhaust passage, the exhaust gas is used to warm the vaporizer or regulator and exhaust the condensed water generated by warming the vaporizer or regulator. It can be used for cooling the purification catalyst. Furthermore, since the switching valve for opening and closing the communication path and the second bypass path are provided, the exhaust gas can be connected to the vaporizer or regulator even in a cold state where it is not necessary to cool the exhaust purification catalyst. It is possible to pass through, and the functions of the vaporizer and the regulator can be maintained in a good state.

It is a figure showing a schematic structure of a gas engine concerning one embodiment of the present invention. It is the schematic for demonstrating the structure of the condensed water storage part of the gas engine shown in FIG. FIG. 2 is a schematic diagram for explaining a configuration of an exhaust purification catalyst of the gas engine shown in FIG. 1. It is a figure which shows schematic structure of the gas engine which concerns on other embodiment of this invention.

  Hereinafter, a catalyst cooling device for an engine constructed according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a schematic configuration according to an embodiment of a gas engine including a catalyst cooling device configured according to the present invention.

  A gas engine 1 shown in the figure is a combustion operation using liquefied petroleum gas (LPG) as a fuel gas, and is used as a prime mover for a vehicle, for example. The gas engine 1 includes an engine body 10, an intake passage 2, an exhaust passage 3, a fuel supply passage 5, an exhaust purification catalyst 6, a muffler 7, a fuel gas cylinder 8 (fuel container), a vaporizer 9, and the like. Although only one cylinder is shown in the figure, it may be a single cylinder engine or a multi-cylinder engine.

  As shown in the figure, the engine body 10 includes a cylinder block 4 which is a main component, and a piston 42 is housed in a cylinder 41 formed inside the cylinder block 4 so as to be slidable in the vertical direction. Yes. A cylinder head is fixed to the upper surface of the cylinder block 4 so as to close the upper side of the cylinder 41 (not shown), and an inner wall of the cylinder 41, an upper surface of the piston 42, and a lower surface of the cylinder head are arranged. A combustion chamber 11 is formed between them.

  An intake passage 2 and an exhaust passage 3 are communicated with the combustion chamber 11 via the cylinder head. An intake valve 43 for communicating and blocking the intake passage 2 and the combustion chamber 11 is connected to the cylinder head. An exhaust valve 44 for communicating and blocking the passage 3 and the combustion chamber 11 and an ignition plug 45 for igniting a mixture of gas fuel supplied to the combustion chamber 11 and outside air are disposed.

  A crankshaft 47 connected to the piston 42 via a connecting rod 46 is rotatably supported on the engine body 10. The reciprocating motion of the piston 42 in the vertical direction is converted into a rotational motion and output as a power source. The intake valve 43 and the exhaust valve 44 described above are driven by a camshaft (not shown) that is rotatably supported by the cylinder head, and the rotation of the crankshaft 47 is transmitted to the camshaft. It is opened and closed at a predetermined timing.

  One end of a fuel supply passage 5 for supplying fuel gas is connected to the intake passage 2 via a venturi 51, and a throttle valve 52 for controlling the flow rate of the air-fuel mixture sucked into the combustion chamber 11 is disposed. Is done.

  The other end of the fuel supply passage 5 is connected to a fuel gas cylinder 8 that stores LPG in a liquefied state, and is shut off in the vicinity of the fuel gas cylinder 8 in the fuel supply passage 5 to cut off the supply of LPG to the fuel supply passage 5. A valve 81 is provided. A vaporizer 9 is disposed on the fuel supply passage 5 for vaporizing the fuel gas sent from the fuel gas cylinder 8 in a liquid state. Further, a fuel gas control valve 82 for controlling the flow rate of the fuel gas vaporized by the vaporizer 9 is provided between the vaporizer 9 and the venturi 51.

  The exhaust passage 3 is provided with an exhaust purification catalyst (three-way catalyst) 6 for purifying the exhaust gas Ex in order from the upstream side to the downstream side, and a muffler 7 having a silencing function for reducing the exhaust noise of the engine. Here, “upstream” and “downstream” refer to “upstream” and “downstream” in the direction of the flow of exhaust gas discharged from the combustion chamber 11 through the exhaust passage 3.

  The vaporizer 9 will be described in more detail with reference to FIG. The vaporizer 9 has a function of vaporizing the liquid LPG supplied from the fuel gas cylinder 8 and is partitioned by an inner wall 91 (diaphragm) excellent in thermal conductivity. The vaporizer 9a is configured to vaporize the supplied LPG while reducing the pressure, and the exhaust gas inlet 9b to which the exhaust gas Ex is supplied. The exhaust introduction portion 9b of the vaporizer 9 and the exhaust passage 3 on the downstream side of the exhaust purification catalyst 6 are connected by a first bypass passage 31, and the exhaust gas Ex that has passed through the exhaust purification catalyst 6 passes through the first bypass passage 31. Is supplied to the exhaust introduction part 9b. A condensed water discharge passage 92 is connected to the bottom wall of the exhaust introduction portion 9b, and the condensed water is supplied and stored in the condensed water storage portion 93 via the condensed water discharge passage 92. In the drawing, the structure of the vaporizing portion 9a of the vaporizer 9 is shown in a simplified manner for convenience of explanation, and the detailed structure is omitted because it is a well-known technique.

  The condensed water storage unit 93 will be described in more detail with reference to FIGS. The condensed water storage part 93 is disposed below the vaporizer 9, and the condensed water discharge passage 92 described above is connected to the top wall of the condensed water storage part 93. A communication passage 94 for supplying the condensed water W to the exhaust purification catalyst 6 is connected to the bottom wall of the condensed water storage section 93. In addition, one end of the second bypass passage 95 is connected to the side wall of the condensed water storage portion at a predetermined height h from the bottom wall. A switching valve 96 is disposed in the communication passage 94 at a position close to the exhaust purification catalyst 6, and the switching valve 96 is opened when a predetermined temperature is reached, and the predetermined valve is opened. A thermostat (not shown) is provided that acts to shut off when the temperature falls below.

  The other end of the second bypass passage 95 is connected to the exhaust passage 3 further downstream of the muffler 7 disposed downstream of the exhaust purification catalyst 6, and the exhaust introduction portion 9 b of the vaporizer 9, condensed water The exhaust gas Ex that has passed through the storage section 93 and the condensed water W that has overflowed in the condensed water storage section 93 are discharged.

  Next, the exhaust purification catalyst 6 to which the condensed water W is supplied will be described in detail with reference to FIGS. FIG. 3A is a schematic cross-sectional view of the exhaust purification catalyst 6 as seen from the side in the direction in which the exhaust gas Ex flows. The exhaust purification catalyst 6 includes a catalyst carrier 61 that functions as a three-way catalyst, an inner cylinder 62 that covers and holds the catalyst carrier 61, and an outer cylinder 63 that covers the inner cylinder 62 so as to form a gap 6a. The catalyst carrier 61, the inner cylinder 62, and the outer cylinder 63 are supported by a front end portion and a rear end portion viewed in the exhaust gas flow direction. A communication path 94 is connected to the upper part of the outer cylinder 63 via a switching valve 96 having a thermostat, and one end of a condensed water return path 64 is connected to the lower side of the outer cylinder 63. The other end of the condensed water return passage 64 is connected to the second bypass passage 95 and communicates with the exhaust passage 3 on the downstream side of the muffler 7. The other end of the condensed water return passage 64 may be directly connected to the exhaust passage 3 without being connected to the second bypass passage 95. FIG. 3B shows a schematic cross-sectional view of the exhaust purification catalyst 6 as viewed from the direction in which the exhaust gas Ex flows. As can be understood from the drawing, the gap 6 a is the entire outer periphery of the catalyst carrier 61. When the condensed water W is supplied from above via the communication path 94, the gap 6 a is filled with the condensed water W, and the catalyst carrier 61 is cooled via the inner cylinder 62. Then, the condensed water W that has cooled the catalyst carrier 61 is returned to the exhaust passage 3 via the condensed water return passage 64. The inner cylinder 62 and the outer cylinder 63 constituting the catalyst case are preferably made of stainless steel in order to prevent corrosion due to the condensed water W.

  The catalyst cooling device in this embodiment includes the exhaust purification catalyst 6, the first bypass passage 31, the condensed water storage section 93, the communication passage 94, the switching valve 96, the condensed water return passage 64, and the second bypass passage 95. Consists of including.

  The shut-off valve 81, the fuel gas control valve 82, the throttle valve 52, and the spark plug 45 described above are electrically connected to control means (controller) (not shown) and appropriately controlled. Various sensors (accelerator opening sensor, engine speed sensor, intake flow rate sensor in the intake passage 2, A / F sensor in the exhaust passage 3, exhaust temperature sensor, exhaust purification catalyst temperature sensor, etc.) are connected to the gas engine as appropriate. 1 is used for control.

  The gas engine 1 of this embodiment generally has the above-described configuration, and the operation thereof will be described below.

  When the gas engine 1 of the present embodiment is started according to the driver's instruction, the shut-off valve 81 is opened, and liquid LPG is supplied from the fuel gas cylinder 8 to the fuel supply passage 5. The liquid LPG supplied to the fuel supply passage 5 is supplied to the vaporization section 9a of the vaporizer 9 to be reduced in pressure and vaporized, and the degree of opening of the fuel gas control valve 81 is controlled, whereby intake air is obtained via the venturi 51. It is supplied to the passage 2. The opening degree of the fuel gas control valve 81 is determined based on the accelerator opening degree, the engine speed, the intake air flow rate of the intake passage 2, the A / F of the exhaust passage 3, etc., and a control signal is generated and adjusted by the control means. Is done.

  Here, immediately after the start of the gas engine 1, there is a concern that the temperature of the vaporizer 9 is low and the fuel vaporization efficiency is not stable. In this respect, in the present embodiment, since the high-temperature exhaust gas Ex is supplied from the exhaust passage 3 to the exhaust introduction portion 9b of the vaporizer 9 via the first bypass passage 31, it passes through the vaporizer 9 immediately after the engine is started. The temperature of liquid LPG is increased and vaporization is promoted. Therefore, the controllability of the supply amount of the fuel gas by the fuel gas control valve 82 is excellent, and the operation of the gas engine 1 is also stabilized quickly. The exhaust gas Ex introduced into the exhaust gas introduction portion 9 b of the vaporizer 9 is cooled by heat exchange, moisture contained in the exhaust gas Ex is condensed into condensed water, and the condensed water storage portion 93 is condensed through the condensed water discharge passage 92. Is discharged and stored.

  Immediately after starting the engine, the temperature of the exhaust purification catalyst 6 is also low, and it is necessary to raise it to a certain temperature range (for example, about 400 ° C. to 600 ° C.) in order to function well as a catalyst. As described above, the switching valve 96 disposed in the communication path 94 incorporates a thermostat, and when the temperature of the exhaust purification catalyst 6 is below the temperature range, the switching valve 96 is It is set not to be released. Therefore, while the switching valve 96 is not opened and the communication path 94 is shut off, the condensed water W remains stored in the condensed water storage section 93. Here, as shown in FIG. 2, a second bypass passage 95 is connected to the side wall of the condensed hydraulic storage section 93 at a predetermined height h from the bottom wall, and the stored condensed water W is stored. Is discharged from the second bypass passage 95 and discharged to the exhaust passage 3 on the downstream side of the muffler 7.

  As described above, a general gas engine is higher than the exhaust temperature of a gasoline engine or the like (for example, about 750 ° C. at the exhaust temperature during rated operation), and the temperature of the exhaust purification catalyst 6 depends on the operating state. There is concern that the durability of the exhaust purification catalyst 6 may be affected beyond the certain temperature range. Therefore, in the present embodiment, when the temperature of the exhaust purification catalyst 6 becomes a temperature at which thermal deterioration is a concern (for example, 700 ° C. or more), the switching valve 96 is operated by the action of the thermostat provided in the switching valve 96. The condensed water W is supplied from the condensed water storage portion 93 to the gap 6 a of the exhaust purification catalyst 6. When the temperature of the exhaust purification catalyst 6 is lowered to a temperature lower than 700 ° C. by supplying the condensed water W, the switching valve 96 is shut off by the action of the thermostat, and the supply of the condensed water W is stopped. By such an operation of the switching valve 96, the temperature of the exhaust purification catalyst 6 is maintained in a temperature range that functions well as a catalyst and does not affect the durability.

  In the present embodiment, the condensate storage part 93 is installed at a position higher than the exhaust purification catalyst 6, that is, above the exhaust purification catalyst 6, and the communication path 94 communicates with the upper part of the exhaust purification catalyst 6. Accordingly, the switching valve 96 disposed in the communication path 94 is opened by the action of the thermostat, so that the condensed water W can be supplied to the exhaust purification catalyst 6 by gravity, and a special drive source is mounted. The exhaust purification catalyst 6 can be cooled without any problem.

  In the present embodiment, the first bypass passage 31 for introducing the exhaust gas Ex into the vaporizer 9 is connected to the exhaust passage 3 on the downstream side of the exhaust purification catalyst 6 and on the upstream side of the muffler 7. The second bypass passage 95 connected to the exhaust passage 3 is connected to the exhaust passage 3 on the downstream side of the muffler 7. A pressure difference is generated between the exhaust passage 3 on the upstream side of the muffler 7 and the exhaust passage 3 on the downstream side of the muffler 7 opened to the atmosphere due to the exhaust resistance of the muffler 7. The exhaust gas Ex can be supplied to the vaporizer 9 via the bypass passage 31, and the exhaust gas Ex passing through the condensed water storage portion 93 and the overflowed condensed water W are caused to flow backward via the second bypass passage 95. And can be efficiently discharged into the exhaust passage 3. Further, since the overflowed condensed water W is returned directly to the exhaust passage 3 without being discarded to the outside, the condensed water W can be vaporized and discharged by the heat of the exhaust gas. Contamination is suppressed.

  In the above-described embodiment, an example in which the technical idea of the present invention is applied to a gas engine using LPG as fuel gas has been shown. However, the technical idea of the present invention is not limited to a gas engine using LPG as fuel gas, and CNG It can also be applied to gas engines that use city gas as fuel gas.

  With reference to FIG. 4, another embodiment in which the technical idea of the present invention is applied to a gas engine using CNG as fuel gas will be described. In the description of the other embodiments, the main configuration is substantially the same as that of the gas engine described with reference to FIG. Will be mainly described.

  The gas engine 100 using CNG as a fuel gas includes a fuel gas cylinder 80 (fuel container) in which fuel gas is compressed and filled at a pressure higher than that of LPG. One end of a fuel supply passage 5 for supplying fuel gas is connected to the intake passage 2, and the other end is connected to a fuel gas cylinder 80. A fuel gas cylinder 80 in the fuel supply passage 5 is disposed in the vicinity of the fuel gas cylinder 80. A shut-off valve 81 that shuts off the supply of CNG to the supply passage 5 is provided. A regulator 90 for reducing the pressure of the high-pressure fuel gas sent out from the fuel gas cylinder 80 is disposed on the fuel supply passage 5.

  The regulator 90 functions to depressurize the high-pressure CNG supplied from the fuel gas cylinder 80, is partitioned by an inner wall 91 (diaphragm) excellent in thermal conductivity, and is supplied via the fuel supply passage 5. The decompression unit 90a for decompressing the CNG and the exhaust introduction unit 90b to which the exhaust gas Ex is supplied. The exhaust introduction part 90b of the regulator 90 and the exhaust passage 3 on the downstream side of the exhaust purification catalyst 6 are connected by a first bypass passage 31, and the exhaust gas Ex that has passed through the exhaust purification catalyst 6 passes through the first bypass passage 31. Is supplied to the exhaust introduction part 90b. A condensed water discharge passage 92 is connected to the bottom wall of the exhaust introduction portion 90 b, and the condensed water W is supplied to the condensed water storage portion 93 through the condensed water discharge passage 92. In addition, since the structure of the pressure reduction part 90a of the regulator 90 is a known technique, the detailed structure is abbreviate | omitted in the figure.

When the gas engine 100 is started, the shut-off valve 81 is opened, and high-pressure fuel gas (for example, 200 kgf / cm ² ) is sent to the pressure reducing unit 90 a of the regulator 90. The pressure of the fuel gas sent to the decompression unit 90a is decompressed by the decompression unit 90a and is reduced to, for example, about 3.5 kgf / cm ² . The decompressed fuel gas is adjusted to an amount corresponding to the operating state by a fuel gas control valve 82 disposed on the fuel supply passage 5 and supplied to the intake passage 2.

  When the fuel gas supplied from the fuel gas cylinder 80 is depressurized by the regulator 90, the pressure difference before and after the regulator 90 is large, so the temperature of the regulator 90 decreases due to the influence of adiabatic expansion. When the temperature of the regulator 90 decreases, the flow rate of the fuel gas that passes through the regulator 90 and is supplied to the intake passage 2 of the gas engine 100 is affected. As a result, the operation of the gas engine 100 becomes unstable. There is a fear. In this regard, in the present embodiment, exhaust gas having a high temperature is introduced into the exhaust gas introduction portion 90 b of the regulator 90 through the first bypass passage 31, the regulator 90 is heated and the fuel gas is warmed, and the intake passage 2 is heated. The flow rate of the supplied fuel gas is stabilized.

  A part of the exhaust gas Ex supplied to the exhaust introduction part 90b of the regulator 90 becomes condensed water W by heat exchange in the regulator 90, and is discharged to the condensed water storage part 93 through the condensed water discharge path 92. Stored. The condensed water W stored in the condensed water storage section 93 is used for cooling the exhaust purification catalyst 6 by the same operation as the gas engine 1 described with reference to FIG. it can.

  The present invention is not limited to the above-described embodiment described with reference to FIGS. 1 and 4, and various modifications can be assumed as long as they are included in the technical scope of the present invention. For example, in the above-described embodiment, the switching valve 96 provided with a thermostat is provided in the communication passage 94 that supplies the condensed water W from the condensed water storage portion 93 to the exhaust purification catalyst 6, and the communication passage is opened and closed by the action of the thermostat. Although the present invention is not limited to this, for example, a catalyst temperature sensor is provided in the exhaust purification catalyst 6, and a switching valve that is electrically operated based on the temperature of the catalyst carrier 61 detected by the catalyst temperature sensor is arranged. It can also be set up.

  In the above-described embodiment, an example in which the catalyst carrier 61 mounted on the exhaust purification catalyst is a three-way catalyst has been described. However, the present invention is not limited to this, and other exhaust purification catalysts (oxidation catalyst, NOx catalyst) Etc.).

  In the embodiment described above, the exhaust gas Ex is always supplied to the vaporizer 9 or the regulator 90 via the first bypass passage 31, but the present invention is not limited to this, and the first bypass passage 31. An on-off valve may be provided on the top, and the amount of exhaust gas passing through the first bypass passage 31 may be adjusted according to the temperature state of the vaporizer 9 or the regulator 90 and the exhaust purification catalyst 6.

  Further, in the above-described embodiment, the vaporizer 9 or the regulator 90 and the condensed water storage unit 93 are configured separately, and the condensed water W is stored in the condensed water storage unit 93 via the condensed water discharge passage 92. However, the present invention is not limited to this, and the vaporizer 9 or the regulator 90 and the condensed water storage part 93 may be configured integrally.

1: Gas engine 2: Intake passage 3: Exhaust passage 4: Cylinder block 5: Fuel supply passage 6: Exhaust purification catalyst 7: Muffler 8, 80: Fuel gas cylinder (fuel container)
9: Vaporizer 10: Engine body 11: Combustion chamber 31: First bypass passage 41: Cylinder 42: Piston 43: Intake valve 44: Exhaust valve 45: Spark plug 46: Connecting rod 47: Crankshaft 51: Venturi 52: Throttle valve 6a: Clearance 61: Catalyst carrier 62: Inner cylinder 63: Outer cylinder 64: Condensate return passage 81: Shut-off valve 82: Fuel gas control valve 90: Regulator 9a: Vaporization section 9b: Exhaust introduction section 90a: Decompression section 90b: Exhaust Introduction part 91: inner wall (diaphragm)
92: Condensate discharge passage 93: Condensate storage section 94: Communication passage 95: Second bypass passage 96: Switching valve

Claims (5)

A catalyst cooling device for cooling an engine exhaust purification catalyst,
The engine includes an exhaust purification catalyst disposed in an exhaust passage, a fuel container that stores fuel, a fuel supply passage that supplies fuel from the fuel container to the engine, and a fuel supply passage that is disposed on the fuel supply passage. And at least a vaporizer,
The catalyst cooling device includes:
An exhaust purification catalyst configured to include an inner cylinder that covers and holds the catalyst carrier, and an outer cylinder that covers the catalyst carrier so as to form a gap between the inner cylinder,
A first bypass passage for extracting a part of the exhaust gas from an exhaust passage downstream of the exhaust purification catalyst and supplying the exhaust gas to the vaporizer;
A condensed water storage section for storing condensed water generated by supplying exhaust gas to the vaporizer;
A communication path for supplying the condensed water stored in the condensed water storage section to the gap of the exhaust purification catalyst;
A switching valve that is disposed in the communication path and opens and shuts off the communication between the condensed water storage portion and the gap according to the temperature of the exhaust purification catalyst;
A condensed water return passage for discharging the condensed water that has passed through the gap to an exhaust passage downstream of the exhaust purification catalyst;
And a second bypass passage that discharges condensed water from the condensed water reservoir to the exhaust passage without passing through the gap. A catalyst cooling device for cooling an engine exhaust purification catalyst,
The engine includes an exhaust purification catalyst disposed in an exhaust passage, a fuel container that stores fuel, a fuel supply passage that supplies fuel from the fuel container to the engine, and a fuel supply passage that is disposed on the fuel supply passage. And at least a regulator,
The catalyst cooling device includes:
An exhaust purification catalyst configured to include an inner cylinder that covers and holds the catalyst carrier, and an outer cylinder that covers the catalyst carrier so as to form a gap between the inner cylinder,
A first bypass passage for extracting a part of the exhaust gas from the exhaust passage downstream of the exhaust purification catalyst and supplying the exhaust gas to the regulator;
A condensate storage part for storing condensate generated by supplying exhaust gas to the regulator;
A communication path for supplying the condensed water stored in the condensed water storage section to the gap of the exhaust purification catalyst;
A switching valve that is disposed in the communication path and opens and shuts off the communication between the condensed water storage portion and the gap according to the temperature of the exhaust purification catalyst;
A condensed water return passage for discharging the condensed water that has passed through the gap to an exhaust passage downstream of the exhaust purification catalyst;
And a second bypass passage that discharges condensed water from the condensed water reservoir to the exhaust passage without passing through the gap.   The switching valve is provided with a thermostat that operates according to the temperature of the exhaust purification catalyst, and shuts off the communication passage when the temperature of the exhaust purification catalyst is equal to or lower than a predetermined temperature, and the communication valve when the temperature is higher than the predetermined temperature. The catalyst cooling device according to claim 1 or 2, wherein the switching valve is operated so as to open the passage.   The catalyst cooling device according to any one of claims 1 to 3, wherein the condensate storage unit is installed above the exhaust purification catalyst, and the communication path communicates with an upper portion of the exhaust purification catalyst.   A muffler is disposed in an exhaust passage on the downstream side of the exhaust purification catalyst, an exhaust extraction portion of the first bypass passage is provided in an exhaust passage between the exhaust purification catalyst and the muffler, and further The catalyst cooling device according to any one of claims 1 to 4, wherein a discharge portion to the exhaust passage of the second bypass passage is provided on the downstream side of the muffler.