JP5010662B2 - Exhaust purification device - Google Patents

Description

  The present invention relates to an exhaust emission control device.

  Conventionally, in order to reduce NOx (nitrogen oxides) contained in exhaust discharged from an internal combustion engine, a selective reduction type NOx catalyst (SCR catalyst) is disposed inside the exhaust pipe, and ammonia is used as a reducing agent. An exhaust emission control device that reduces NOx to nitrogen and water is known. This exhaust purification device supplies urea water into exhaust gas from a urea water supply nozzle arranged inside an exhaust pipe, and generates ammonia from urea water by the heat of exhaust gas, thereby reducing NOx to nitrogen and water. It is. However, when the supply of urea water is stopped, the urea water remaining in the urea water supply nozzle evaporates due to the heat of the exhaust, so that urea precipitates and the urea water supply nozzle is blocked. was there.

  In such an exhaust purification device, for example, as in Patent Document 1, when the introduction of urea water is stopped, pressurized air is supplied to the reducing agent supply line which is the urea water supply path, and the inside of the reducing agent supply line And the urea water remaining inside the reducing agent charging nozzle, which is a urea water supply nozzle, is discharged into the exhaust pipe to prevent the reducing agent charging nozzle from being blocked due to precipitation of urea.

  However, when the supply of urea water is stopped as NOx contained in the exhaust gas decreases, the urea water remaining in the reducing agent supply line and the reducing agent charging nozzle is discharged into the exhaust pipe. As a result, there was a problem that ammonia more than the amount necessary for the reduction of NOx contained in the exhaust gas was generated, and ammonia that was not used for the reduction reaction was released to the atmosphere (ammonia slip). Ammonia can be oxidized by an oxidation catalyst, but cannot be used in marine engines that use heavy oil as fuel because the oxidation catalyst is poisoned by sulfur contained in heavy oil. Further, when the temperature of the exhaust gas is lowered due to the stop of the internal combustion engine, if the urea water remaining in the reducing agent supply line and the reducing agent charging nozzle is discharged into the exhaust pipe, ammonia is discharged. The water evaporates without being decomposed, and urea is precipitated. There is a problem that the NOx catalyst is clogged by the precipitated urea, or the urea adheres to the surface of the NOx catalyst to deteriorate the catalyst performance. In addition, even if pressurized air is supplied to the reducing agent supply line from the upstream side of the reducing agent supply line arranged in an ascending gradient, the pressurized air remains in the urea water remaining inside the reducing agent supply line. It was disadvantageous in that it passed through as bubbles, and all the urea water could not be discharged, and the blocking of the reducing agent charging nozzle could not be effectively prevented.

JP 2004-360578 A

  The present invention has been made in view of such problems, and the exhaust gas that can discharge the urea water remaining inside the urea water supply nozzle to the outside of the exhaust pipe without discharging the urea water to the inside of the exhaust pipe. The purpose is to provide a purification device.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

That is, according to the first aspect of the present invention, the liquid flow path to which urea water is supplied, the gas flow path to which pressurized air is supplied, and the liquid flow path and the gas flow path are communicated with each other upstream, A mixing channel having a smaller diameter on the downstream side than the side , an injection port is formed at the downstream end of the mixed oil channel, and supplied to the urea channel and the gas channel supplied to the liquid channel And a urea water supply nozzle capable of mixing the pressurized air to be injected into the exhaust pipe connected to the internal combustion engine from the injection port, and urea water to the liquid channel. A urea water supply unit that can be supplied via a supply channel, a pressurized air supply unit that can supply pressurized air to the gas channel via a second supply channel, and the first supply channel A first position for blocking the first supply channel and opening the liquid channel to the atmosphere, or A exhaust gas purification device comprising a switching valve capable of holding, to the second position for communicating the first supply passage, when the switching valve is held in the first position, from the pressurized air supply section By the pressurized air supplied to the mixing channel, urea water in the liquid channel released to the atmosphere is pushed toward the upstream of the liquid channel and discharged to the outside of the exhaust pipe, and the switching valve Is held at the second position, the pressurized air supplied from the pressurized air supply unit to the mixing channel and the urea water supplied from the urea water supply unit to the mixing channel are mixed. And is injected into the exhaust pipe from the injection port .

That is, the invention of claim 2 is provided with a pressurized air valve that is provided in the second supply channel and communicates or blocks the second supply channel, and controls the switching valve and the pressurized air valve. And a control unit that controls the switching valve and the pressurized air valve, and the control unit switches the switching valve from the second position to the first position for a predetermined time. The second supply flow path is blocked by the pressurized air valve after the passage.

  As effects of the present invention, the following effects can be obtained.

  In claim 1, when the position of the switching valve is switched to the first position, the supply of urea water to the liquid flow path of the urea water supply nozzle is stopped and the liquid flow path of the urea water supply nozzle is released to the atmosphere. The As a result, the pressurized air supplied to the gas flow path of the urea water supply nozzle is from the vicinity of the urea water supply nozzle outlet, which is the most downstream side of the liquid flow path of the urea water supply nozzle, to the liquid flow path of the urea water supply nozzle. The urea water in the liquid flow path of the urea water supply nozzle is discharged to the outside of the exhaust pipe through the switching valve. That is, the urea water remaining inside the urea water supply nozzle can be discharged from the inside of the urea water supply nozzle without being discharged into the exhaust pipe. Thereby, unnecessary ammonia is not generated and released from the exhaust pipe into the atmosphere. Further, urea does not precipitate inside the exhaust pipe and clog the NOx catalyst, or urea adheres to the surface of the NOx catalyst and does not deteriorate the catalyst performance. In addition, since pressurized air flows from the most downstream side of the liquid flow path of the urea water supply nozzle, the liquid flow path is arranged in an upward gradient with respect to the exhaust pipe depending on the installation state of the urea water supply nozzle. Even in this case, the urea water can be discharged without discharging only the pressurized air.

  In the second aspect, in addition to the effect of the first aspect, even if the supply of the urea water is stopped, the pressurized air is supplied to the urea water supply nozzle for a predetermined time. As a result, since the pressurized air flows into the liquid flow path of the urea water supply nozzle, the urea water remaining in the urea water supply nozzle is not discharged into the exhaust pipe, and the urea water supply nozzle It can be discharged from the inside.

The figure which shows the structure of the exhaust gas purification apparatus which concerns on one Embodiment of this invention. The partial cross section figure which shows the urea water supply nozzle of the exhaust gas purification device which relates to one execution form of this invention. (A) The figure which shows the state which is supplying the urea water from the urea water supply nozzle of the exhaust gas purification apparatus which concerns on one Embodiment of this invention into the inside of an exhaust pipe. (B) The figure which shows the state which is discharging | emitting urea water to the exterior of an exhaust pipe from the urea water supply nozzle of the exhaust gas purification apparatus which concerns on one Embodiment of this invention. The flowchart figure which shows the control procedure of the exhaust gas purification device which concerns on one Embodiment of this invention.

  Hereinafter, an exhaust purification device 1 according to an embodiment of the present invention and an engine 2 that is an internal combustion engine to which the exhaust purification device 1 is applied will be described with reference to FIGS. 1 and 2. In this embodiment, “upstream side” indicates the upstream side in the fluid flow direction, and “downstream side” indicates the downstream side in the fluid flow direction.

  As shown in FIG. 1, the engine 2 is a single-cylinder engine or a multi-cylinder engine. In the present embodiment, the engine 2 is an in-line four-cylinder engine having four cylinders 5, 5, 5, 5. The engine 2 mixes and burns the outside air supplied through the intake pipe 3 and the fuel supplied from the fuel injection valves 4, 4, 4, 4 inside the cylinders 5, 5, 5, 5. The exhaust gas to be discharged is discharged to the outside through the exhaust pipe 6. The engine 2 includes an engine speed detection unit 7 and an exhaust temperature detection unit 8, and is controlled by an ECU 9 having an output calculation unit 9a that calculates the output of the engine 2.

  The engine speed detector 7 detects the engine speed R. The engine speed detection unit 7 includes a rotary encoder and the like, and is provided on the output shaft of the engine 2. The engine speed detector 7 is a rotary encoder in this embodiment, but is not particularly limited to this, and any engine speed detector that can detect the engine speed R may be used.

  The exhaust gas temperature detector 8 detects the exhaust gas temperature T of the engine 2. The exhaust temperature detection unit 8 includes a temperature sensor or the like, and is disposed in the middle of the exhaust pipe 6 and upstream of the NOx catalyst 90. In addition, the position where the temperature sensor is arranged and the number of temperature sensors are not particularly limited in the present embodiment, and any configuration that can appropriately detect the exhaust gas temperature T may be used.

  The ECU 9 controls the engine 2. The ECU 9 stores various programs and data for controlling the engine 2. Further, the ECU 9 includes an output calculation unit 9a that calculates the output of the engine 2. The ECU 9 may be configured such that a CPU, ROM, RAM, HDD, and the like are connected by a bus, or may be configured by a one-chip LSI or the like.

  As shown in FIG. 1, the ECU 9 is connected to the fuel injection device 4a, obtains an operation amount of the fuel injection device 4a, and calculates the fuel injection amount injected by the fuel injection valves 4, 4, 4, 4. Is possible.

  The ECU 9 is connected to the engine speed detection unit 7 and can acquire the engine speed R detected by the engine speed detection unit 7.

  The ECU 9 is connected to the exhaust gas temperature detection unit 8 and can acquire the exhaust gas temperature T detected by the exhaust gas temperature detection unit 8.

  The ECU 9 can calculate the engine output W from the fuel injection amount and the engine speed R by the output calculation unit 9a. The output calculation unit 9a calculates an engine output W from the fuel injection amount and the engine speed R using an engine output map or the like. The engine output W is calculated from the engine output map or the like in this embodiment, but is not particularly limited, and an output detection unit that detects the output of a generator (not shown) connected to the engine 2. The engine output W may be acquired from 9b.

  The exhaust purification device 1 purifies exhaust exhausted from the engine 2. The exhaust purification device 1 is provided in the engine 2, and includes a urea water supply nozzle 10, a pressurized air supply unit 20, a urea water supply unit 30, a switching valve 40, a NOx detection unit 50, a control unit 60, and a first supply flow path 70. , A second supply flow path 80, a NOx catalyst 90, and the like.

  The urea water supply nozzle 10 supplies urea water into the exhaust pipe 6. The urea water supply nozzle 10 is composed of a tubular member, and is provided with one side (downstream side) thereof inserted from the outside to the inside of the exhaust pipe 6. The urea water supply nozzle 10 includes a double pipe 11, a liquid cap 12, an air cap 13, and the like.

  As shown in FIG. 2, the double pipe 11 is a main constituent member of the urea water supply nozzle 10 and constitutes a urea water flow path and a pressurized air flow path. The double pipe 11 is formed in a substantially L shape by bending one end (downstream side) with respect to the main body, one side is located inside the exhaust pipe 6 and the other side (upstream side) is It arrange | positions so that it may be located outside the exhaust pipe 6. FIG. At this time, the main body of the double pipe 11 is arranged so that its axial direction is substantially perpendicular to the exhaust flow direction of the exhaust pipe 6, and the downstream end of the double pipe 11 is located inside the exhaust pipe 6. It arrange | positions so that the said NOx catalyst 90 may be opposed to the upstream of the NOx catalyst 90 arrange | positioned. The downstream end of the double pipe 11 is arranged so as to face the NOx catalyst 90 in the present embodiment, but is not particularly limited to this, and may be arranged inside the exhaust pipe 6. That's fine.

  The double pipe 11 includes an outer pipe 11b and an inner pipe 11a disposed inside the outer pipe 11b. The inner pipe 11a is configured with a liquid flow path 11c that is a flow path of urea water. In the gap between the outer tube 11b and the inner tube 11a, a gas flow channel 11d that is a flow channel of pressurized air is formed. A connecting portion (not shown) that can be connected to the exhaust pipe 6 in a watertight manner is formed in the middle of the outside of the outer pipe 11b. A female screw portion 11e is formed at the downstream end of the inner tube 11a. A liquid supply port 11f that communicates with the liquid flow path 11c and a gas supply port 11g that communicates with the gas flow path 11d are configured at the upstream end of the double pipe 11. The double pipe 11 is arranged with an ascending gradient with respect to the exhaust pipe 6 so that the air mixed in the urea water does not stay inside the liquid flow path 11c.

  The liquid cap 12 is for injecting urea water. The liquid cap 12 is formed from a substantially cylindrical member and is disposed on the downstream side of the double pipe 11. One end (downstream side) end of the liquid cap 12 is formed in a substantially conical shape with the axial center as a center. A substantially cylindrical convex portion 12a is formed in the central portion of the end portion so as to protrude in the axial direction. A male screw portion 12b is formed at the other end (upstream side) end of the liquid cap 12 so as to protrude in the axial direction. Furthermore, a liquid channel 12c, which is a urea water channel, is formed in the axial center of the liquid cap 12 so as to penetrate the entire liquid cap 12 in the axial direction from the male screw portion 12b to the convex portion 12a. The liquid channel 12c is reduced in diameter toward the downstream side in the middle, and is formed so that the inner diameter of the downstream end of the liquid channel 12c is smaller than the inner diameter of the upstream end of the liquid channel 12c. . In addition, a plurality of gas flow paths 12d, which are flow paths of pressurized air, are formed on the radially outer side of the liquid flow path 12c from the upstream end toward the downstream end so as to penetrate the entire liquid cap 12 in the axial direction. Is done.

  The male screw portion 12 b of the liquid cap 12 is screwed into the female screw portion 11 e of the double pipe 11. Thereby, the double pipe 11 and the liquid cap 12 are connected, the liquid flow path 12c and the liquid flow path 11c of the double pipe 11 are communicated, and the gas flow between the gas flow path 12d and the double pipe 11 The path 11d is communicated. A male screw portion 12e is formed in the middle of the outer peripheral portion of the liquid cap 12 portion. In this way, urea water can be supplied from the liquid channel 11c of the double tube 11 to the liquid channel 12c, and pressurized air can be supplied from the gas channel 11d of the double tube to the gas channel 12d. Is done. The liquid cap 12 is disposed with an ascending gradient so that the air mixed in the urea water does not stay inside the liquid flow path 12c.

  The air cap 13 atomizes and sprays urea water. The air cap 13 is formed of a substantially cylindrical member and is disposed on the downstream side of the liquid cap 12. In the axial center of the air cap 13, a hole having a substantially conical diameter-reducing portion whose diameter is reduced toward one side (downstream side) in the middle is directed from the other side (upstream side) end toward the downstream side end. And formed to penetrate. The upstream end of the hole is formed to have an inner diameter into which the downstream end of the liquid cap 12 can be inserted. A concave portion 13a having an inner diameter larger than the outer diameter of the convex portion 12a of the liquid cap 12 is formed in the axial center portion of the reduced diameter side end of the reduced diameter portion. The downstream side of the hole formed with a smaller diameter than the upstream side of the hole is configured as a urea water mixing channel 13c. A collar portion 13 b is formed on the outer peripheral portion of the upstream end portion of the air cap 13.

  A nut 13f hooked to the collar portion 13b of the air cap 13 is screwed into the male screw portion 12e of the liquid cap 12. As a result, the air cap 13 and the liquid cap 12 are connected, the downstream end of the liquid cap 12 is inserted into the upstream end of the hole, and the convex portion 12a of the liquid cap 12 is inserted into the recess 13a. The At this time, the air cap 13 includes a gap formed between the reduced diameter portion and the downstream end portion of the liquid cap 12, and a gap formed between the concave portion 13a and the convex portion 12a of the liquid cap 12. Thus, the gas flow path 13d, which is a flow path for pressurized air, is configured to communicate with the mixing flow path 13c. In this way, urea water can be supplied to the mixing channel 13c from the liquid channel 12c formed in the convex portion 12a of the liquid cap 12, and pressurized air can be supplied from the gas channel 13d. That is, the air cap 13 is configured to be capable of injecting urea water by being screwed into the liquid cap 12 and using the downstream end of the mixing channel 13c as the injection port 13e.

  As described above, the urea water supply nozzle 10 includes the liquid cap 12 that injects urea water at one end (downstream side) and the air cap 13, and is configured to inject urea water toward the NOx catalyst 90. Is done. In the present embodiment, the configuration of the urea supply nozzle includes the fluid flow channel 12c, the gas flow channel 13d, and the mixing flow channel 13c formed from the liquid cap 12 and the air cap 13, but is not particularly limited. Instead, the fluid flow path 12c, the gas flow path 13d, and the mixing flow path 13c may be configured.

  As shown in FIG. 1, the pressurized air supply unit 20 supplies pressurized air. The pressurized air supply unit 20 includes a pressurized air supply pump (compressor) 21, an air tank 22, and the like.

  The pressurized air supply pump 21 supplies air after being pressurized (compressed). The pressurized air supply pump 21 is driven by an electric motor 21b, and pumps air from the discharge port 21a when the pressure of the air tank 22 falls below a predetermined pressure. The pressurized air supply pump 21 is not particularly limited in the present embodiment, and may be any pump that can maintain the pressure of the air tank 22. The pressurized air supply pump 21 is configured to stop when the pressure of the air tank 22 reaches a predetermined pressure and to drive when the pressure reaches a predetermined pressure lower than that pressure.

The air tank 22 holds a predetermined amount of air at a predetermined pressure. The air tank 22 is firmly configured to hold high-pressure air inside. The air tank 22 supplies pressurized air having a predetermined pressure from the discharge port 22a.
The air tank 22 is connected to the discharge port 21 a of the pressurized air supply pump 21 via the flow path 81 that constitutes the second supply flow path 80, and is supplied with air from the pressurized air supply pump 21.

The pressurized air valve 23, which is an automatic valve, communicates or blocks the flow path of the pressurized air. The pressurized air valve 23 is a 2-port 2-position electromagnetic valve having ports 23a and 23b. The pressurized air valve 23 can be held at a first position A that closes the port 23a and the port 23b or a second position B that communicates the port 23a and the port 23b. Usually, the pressurized air valve 23 is held at the first position A by the urging force of the spring 23c. Only when the solenoid 23d of the pressurized air valve 23 is energized, the spool provided inside the pressurized air valve 23 slides, and the pressurized air valve 23 is moved from the first position A to the second position B. Can be switched to. The pressurized air valve 23 is configured to be held at the first position A or the second position B by the spring 23c and the solenoid 23d, but is not particularly limited. A configuration in which A or the second position B is held may be employed.
The port 23 a is connected to the discharge port 22 a of the air tank 22 through a flow path 82 that constitutes the second supply flow path 80. The port 23 b is connected to the gas supply port 11 g of the double pipe 11 through a flow path 83 that constitutes the second supply flow path 80. That is, the pressurized air in the air tank 22 is supplied to the gas flow path 11 d of the double pipe 11 through the pressurized air valve 23.

  As shown in FIG. 1, the urea water supply unit 30 supplies urea water. The urea water supply unit 30 includes a urea water supply pump 31, a urea water tank 32, and the like.

  The urea water supply pump 31 supplies urea water. The urea water supply pump 31 is driven by an electric motor 31b. The urea water supply pump 31 is connected to the urea water tank 32 via a flow path 71 that constitutes a part of the first supply flow path 70, and the urea water in the urea water tank 32 is discharged from the discharge port 31a at a predetermined flow rate. Pump. Note that the urea water supply pump 31 is not particularly limited in the present embodiment, and any urea water supply pump that can supply urea water at a predetermined flow rate may be used.

The switching valve 40, which is an automatic valve, switches the urea water flow path. The switching valve 40 is a three-port two-position electromagnetic valve having ports 40a, 40b, and 40c. The switching valve 40 allows the port 40b and the port 40c to communicate with each other and can be held at the first position X for closing the port 40a, or the port 40a and the port 40b for communicating, and the second position Y for closing the port 40c. It is said. Normally, the switching valve 40 is held at the first position X by the biasing force of the spring 40d. Only when the solenoid 40e included in the switching valve 40 is energized, the spool provided in the switching valve 40 slides, and the switching valve 40 is switched from the first position X to the second position Y. The switching valve 40 is configured to be held at the first position X or the second position Y by the spring 40d and the solenoid 40e, but is not particularly limited, and the first position X, Alternatively, the second position Y may be held.
The port 40 a is connected to the discharge port 31 a of the urea water supply pump 31 via a flow path 72 that constitutes a part of the first supply flow path 70. A check valve 41 may be provided in the middle of the flow path 72 constituting a part of the first supply flow path 70. The port 40b is connected to the liquid supply port 11f of the double pipe 11 via a flow path 73 that constitutes a part of the first supply flow path 70 provided. The flow path 73 constituting a part of the first supply flow path 70 is arranged with an ascending gradient so that the air mixed in the urea water does not stay inside the flow path 73 constituting a part of the first supply flow path 70. Established. The port 40 c is connected to the drain pot 42 via the flow path 77. The flow path 77 is disposed with a downward slope so that urea water does not stay in the flow path 77.

  The NOx detector 50 detects the NOx concentration D contained in the exhaust of the engine 2. The NOx detection unit 50 includes a NOx sensor or the like, and is disposed in the middle of the exhaust pipe 6 and upstream of the NOx catalyst 90. Note that the positions where the NOx sensors are arranged and the number of NOx sensors are not particularly limited in the present embodiment, and any configuration capable of appropriately detecting the NOx concentration D may be used. In the present embodiment, the NOx concentration D is detected by detecting the NOx concentration D contained in the exhaust of the engine 2. However, the NOx concentration D is not particularly limited, and the control unit 60 determines the NOx concentration D from the engine output W or the engine speed R. It may be calculated.

  The control unit 60 controls the urea water supply pump 31, the switching valve 40, and the pressurized air valve 23. Specifically, the control unit 60 is configured to detect the NOx concentration D in the exhaust detected by the NOx detecting unit 50, the exhaust temperature T detected by the exhaust temperature detecting unit 8, the engine speed R detected by the engine speed detecting unit 7, The urea water supply pump 31, the switching valve 40, and the pressurized air valve 23 are controlled based on the engine output W calculated by the output calculation unit 9a. The control unit 60 stores various programs and data for controlling the urea water supply pump 31, the switching valve 40, and the pressurized air valve 23. Further, the control unit 60 determines whether or not NOx is being discharged. The reference output W0 of the engine output W, the reference temperature T0 of the exhaust gas temperature T that determines whether or not urea water is decomposed into ammonia, and urea water A reference concentration D0 of NOx concentration D for determining whether or not to supply water, and a flag F that is set to F = 0 when urea water is not supplied and F = 1 when urea water is supplied Is stored. The control unit 60 may be configured such that a CPU, ROM, RAM, HDD, and the like are connected by a bus, or may be configured by a one-chip LSI or the like. The control unit 60 can also be configured integrally with the ECU 9.

  As shown in FIG. 1, the controller 60 includes an engine speed detector 7, an exhaust gas temperature detector 8, an output calculator 9a of the ECU 9, a solenoid 23d of the pressurized air valve 23, a urea water supply pump 31, and a switching valve. The 40 solenoids 40e are respectively connected to the electric motor 31b.

  The controller 60 can acquire the engine speed R detected by the engine speed detector 7, the exhaust temperature T detected by the exhaust temperature detector 8, and the engine output W calculated by the output calculator 9a. It is.

  The control unit 60 can control the electric motor 31b, the solenoid 23d of the pressurized air valve 23, and the solenoid 40e of the switching valve 40, respectively.

  The control unit 60 is connected to the NOx detection unit 50, and can acquire the NOx concentration D detected by the NOx detection unit 50.

  The NOx catalyst 90 promotes a NOx reduction reaction. The NOx catalyst 90 is disposed inside the exhaust pipe 6 and downstream of the urea water supply nozzle 10. The NOx catalyst 90 is formed in a honeycomb shape, and promotes a reaction of reducing NOx contained in exhaust gas into nitrogen and water by ammonia generated by heat and hydrolysis of urea water.

  Below, the operation | movement aspect of the switching valve 40 and the pressurized air valve 23 is demonstrated using FIG.

  As shown in FIG. 1, the air tank 22 has a urea water supply nozzle 10 via a flow path 82 that constitutes the second supply flow path 80, a pressurized air valve 23, and a flow path 83 that constitutes the second supply flow path 80. Connected to the gas supply port 11g.

  As described above, the pressurized air valve 23 is normally held at the first position A. In this case, since the port 23 a and the port 23 b of the pressurized air valve 23 are closed, the pressurized air is not supplied to the gas supply port 11 g of the urea water supply nozzle 10.

  When the controller 60 energizes the solenoid 23d of the pressurized air valve 23, the pressurized air valve 23 is switched from the first position A to the second position B. In this case, since the port 23 a and the port 23 b of the pressurized air valve 23 communicate with each other, the pressurized air is supplied to the gas supply port 11 g of the urea water supply nozzle 10.

  When the controller 60 stops energizing the solenoid 23d of the pressurized air valve 23, the pressurized air valve 23 is switched to the first position A by the urging force of the spring 23c. In this case, since the port 23 a and the port 23 b of the pressurized air valve 23 are closed, the pressurized air is not supplied to the gas supply port 11 g of the urea water supply nozzle 10.

  As shown in FIG. 1, the urea water tank 32 includes a flow path 71 that forms part of the first supply flow path 70, a urea water supply pump 31, and a flow path 72 that forms part of the first supply flow path 70. The check valve 41, the switching valve 40, and the flow path 73 constituting a part of the first supply flow path 70 are connected to the liquid supply port 11 f of the urea water supply nozzle 10.

  As described above, the switching valve 40 is normally held at the first position X. In this case, since the port 40 a and the port 40 b of the switching valve 40 are closed, the urea water is not supplied to the liquid supply port 11 f of the urea water supply nozzle 10. Further, since the port 40 b and the port 40 c of the switching valve 40 are communicated with each other, the liquid supply port 11 f of the urea water supply nozzle 10 is opened to the atmosphere in the drain pot 42 via the flow path 77.

  When the control unit 60 energizes the solenoid 40e of the switching valve 40, the switching valve 40 is switched to the second position Y. In this case, since the port 40 a and the port 40 b of the switching valve 40 are communicated, the urea water is supplied to the liquid supply port 11 f of the urea water supply nozzle 10. Further, since the port 40c of the switching valve 40 is closed, the liquid supply port 11f of the urea water supply nozzle 10 is not opened to the atmosphere.

  When the control unit 60 stops energizing the solenoid 40e of the switching valve 40, the control unit 60 is switched to the first position X by the biasing force of the spring 40d of the switching valve 40. In this case, since the port 40 a and the port 40 b of the switching valve 40 are closed, the urea water is not supplied to the liquid supply port 11 f of the urea water supply nozzle 10. Further, since the port 40 b and the port 40 c of the switching valve 40 are communicated with each other, the liquid supply port 11 f of the urea water supply nozzle 10 is opened to the atmosphere in the drain pot 42 via the flow path 77.

  Below, the operation | movement aspect of the urea water supply nozzle 10 is demonstrated using FIG.1, FIG.2 and FIG.3.

  As shown in FIG. 1, when the supply (injection) of urea water into the exhaust pipe 6 is started, the control unit 60 sets the switching valve 40 to the second position Y, so that the urea water is supplied to the urea water supply nozzle. 10 (double pipe 11) is supplied to the liquid supply port 11f. As shown in FIG. 2 and FIG. 3A, the urea water is the liquid channel 11c of the double pipe 11 and the liquid of the liquid cap 12 at a predetermined pressure as indicated by the black arrows in FIG. The liquid cap 12 is sprayed from the convex portion 12a of the liquid cap 12 to the mixing channel 13c of the air cap 13 through the flow channel 12c.

  In this state, as shown in FIG. 1, the control unit 60 sets the pressurized air valve 23 to the second position B, so that the pressurized air is supplied to the gas supply port 11g of the urea water supply nozzle 10 (double pipe 11). To be supplied. As shown in FIG. 2 and FIG. 3A, the pressurized air is a gas in the gas passage 11d of the double pipe 11 and the gas in the liquid cap 12 at a predetermined pressure as indicated by the white arrow in FIG. The air is injected from the recess 13 a of the air cap 13 to the mixing flow path 13 c of the air cap 13 through the flow path 12 d and the gas flow path 13 d of the air cap 13. As a result, the urea water collides with the pressurized air inside the mixing channel 13 c of the air cap 13 and is atomized, and is injected from the injection port 13 e of the air cap 13.

  As shown in FIG. 1, when the supply (injection) of urea water into the exhaust pipe 6 is stopped, the control unit 60 sets the position of the switching valve 40 to the first position X, whereby the urea water supply nozzle The supply of urea water to the liquid supply port 11f of 10 (double pipe 11) is stopped. Accordingly, the liquid supply port 11 f of the double pipe 11 is opened to the atmosphere via the flow path 73, the switching valve 40, and the flow path 77 that constitute a part of the first supply flow path 70. As shown in FIG. 2 and FIG. 3 (b), the urea water is contained inside the liquid flow path 12 c of the liquid cap 12, inside the liquid flow path 11 c of the double pipe 11, and the double pipe 11 and the switching valve 40. And the inside of the flow path 73 that constitutes a part of the first supply flow path 70 that connects the two.

  In this state, as shown in FIG. 1, the control unit 60 maintains the position of the pressurized air valve 23 at the second position B, so that the pressurized air is gas from the urea water supply nozzle 10 (double pipe 11). It is continuously supplied to the supply port 11g. Since the liquid supply port 11f of the double pipe 11 is open to the atmosphere, as shown in FIGS. 2 and 3 (b), the inside of the liquid flow path 12c of the liquid cap 12, the liquid flow path of the double pipe 11 The pressure inside 11c and the inside of the flow path 73 constituting a part of the first supply flow path 70 is lower than the pressure inside the mixing flow path 13c of the air cap 13 to which pressurized air is supplied. Therefore, the pressurized air inside the mixing flow path 13c of the air cap 13 flows into the liquid flow path 12c of the liquid cap 12 as indicated by the white arrow in FIG. The urea water remaining in the passage 12 c, the liquid passage 11 c of the double pipe 11, and the passage 73 constituting a part of the first supply passage 70 is removed from the switching valve 40 and the drain pot. It pushes to the drain pot 42 side through the flow path 77 which connects 42. That is, the urea water remaining inside the urea water supply nozzle 10 is discharged into the drain pot 42 outside the exhaust pipe 6 without being discharged into the exhaust pipe 6. Further, as described above, the liquid flow path 12c of the liquid cap 12, the liquid flow path 11c of the double pipe 11, and the flow path 73 constituting a part of the first supply flow path 70 are arranged with an ascending gradient. Therefore, only the pressurized air is not discharged to the drain pot 42 by supplying the pressurized air from the downstream side. In this embodiment, the liquid atomizing method is an internal mixing type in which the liquid is atomized inside the mixing flow path 13c of the air cap 13. However, the liquid atomizing method is not particularly limited. It may be an external mixing type that atomizes.

  Below, the control aspect of the urea water supply pump 31, the switching valve 40, and the pressurized air valve 23 by the control part 60 is demonstrated.

  During operation of the engine 2, the control unit 60 acquires the engine output W calculated by the output calculation unit 9a, the exhaust temperature T detected by the exhaust temperature detection unit 8, and the NOx concentration D detected by the NOx detection unit 50, It is determined whether each acquired value is greater than or equal to each reference value. The control unit 60 performs control to supply urea water corresponding to the NOx concentration D into the exhaust pipe 6 when each acquired value is equal to or greater than each reference value. When the acquired values are less than the respective reference values or when the engine 2 is stopped, the control unit 60 stops the supply of the urea water and removes the urea water remaining in the urea water supply nozzle 10 from the exhaust pipe 6. Control to discharge to outside.

  Below, the example of the control aspect of the urea water supply pump 31, the switching valve 40, and the pressurized air valve 23 by the control part 60 is demonstrated concretely using FIG.

  In step S110, the control unit 60 acquires the engine speed R detected by the engine speed detection unit 7, and then shifts the control stage to step S120.

In step S120, the control unit 60 determines whether or not the engine 2 is operating based on the detection value of the engine speed detection unit 7.
As a result, when it is determined that the engine 2 is operating, the control unit 60 moves the control stage to step S130.
If it is determined that the engine 2 is not operating, the control unit 60 proceeds to step S310.

  In step S130, the control unit 60 obtains the engine output W calculated by the output calculation unit 9a, the exhaust temperature T detected by the exhaust temperature detection unit 8, and the NOx concentration D detected by the NOx detection unit 50, and then a control stage. To step S140.

In step S140, the control unit 60 determines whether the exhaust temperature T is equal to or higher than the reference temperature T0.
As a result, when it is determined that the exhaust temperature T is equal to or higher than the reference temperature T0, the control unit 60 shifts the control stage to step S150.
When it is determined that the exhaust temperature T is lower than the reference temperature T0, the control unit 60 moves the control stage to step S310.

In step S150, the control unit 60 determines whether the engine output W is greater than or equal to the reference output W0.
As a result, when it is determined that the engine output W is greater than or equal to the reference output W0, the control unit 60 shifts the control stage to step S160.
When it is determined that the engine output W is less than the reference output W0, the control unit 60 shifts the control stage to step S310.

In step S160, the control unit 60 determines whether the NOx concentration D is equal to or higher than the reference concentration D0.
As a result, when the NOx concentration D is determined to be equal to or higher than the reference concentration D0, the control unit 60 shifts the control stage to step S170.
If it is determined that the NOx concentration D is less than the reference concentration D0, the control unit 60 moves the control step to step S310.

In step S170, the control unit 60 determines whether or not the flag F is F = 0.
As a result, when the flag F determines that F = 0, the control unit 60 moves the control stage to step S180.
If it is determined that the flag F is not F = 0, the control unit 60 repeatedly shifts the control stage to step S110.

  In step S180, the control unit 60 switches the position of the pressurized air valve 23 to the second position B, and then shifts the control stage to step S190.

  In step S190, the control unit 60 switches the position of the switching valve 40 to the second position Y, and then shifts the control stage to step S200.

  In step S200, the control unit 60 starts the urea water supply pump 31 so as to supply urea water corresponding to the NOx concentration D, and then shifts the control stage to step S210.

  In step S210, after setting the flag F to F = 1, the control unit 60 repeatedly shifts the control stage to step S110.

In step S310, the control unit 60 determines whether or not the flag F is F = 1.
As a result, when it is determined that the flag F is F = 1, the control unit 60 shifts the control stage to step S320.
When it is determined that the flag F is not F = 1, the control unit 60 repeatedly shifts the control stage to step S110.

  In step S320, the control unit 60 switches the position of the switching valve 40 to the first position C, and then shifts the control stage to step S320.

  In step S320, the control unit 60 stops the urea water supply pump 31, and then shifts the control stage to step S340.

  In step S340, the control unit 60 switches the position of the switching valve 40 to the first position X and then switches to the position first position A of the pressurized air valve 23 after a predetermined time has elapsed, and then proceeds to step S350. To do.

  In step S350, after setting the flag F to F = 0, the control unit 60 repeatedly shifts the control stage to step S110.

  As described above, the control unit 60 switches the pressurized air valve 23 to the first position A after a lapse of a predetermined time after switching the position of the switching valve 40 to the first position X, so that it remains in the urea water supply nozzle 10. The urea water being discharged can be discharged to the outside of the exhaust pipe 6 (drain pot 42) by the pressure of the pressurized air (see FIGS. 1 and 3).

As described above, the exhaust gas purification apparatus 1 according to this embodiment includes the liquid flow paths 11c and 12c to which urea water is supplied, the gas flow paths 11d, 12d, and 13d to which pressurized air is supplied, and the liquid flow path to the upstream side. 12c and the gas flow path 12d communicate with each other , and have a mixed oil passage 13c formed with a smaller diameter on the downstream side compared to the upstream side, and an injection port 13e is formed at the downstream end of the mixed oil passage 13c. The urea water supplied to the passages 11c and 12c and the pressurized air supplied to the gas passages 11d, 12d, and 13d are mixed in the vicinity of the injection port 13e in the mixing flow channel 13c, and the internal combustion engine is formed from the injection port 13e. A urea water supply nozzle 10 capable of being injected into the exhaust pipe 6 connected to the engine 2, and a urea water supply unit 30 capable of supplying urea water to the liquid flow paths 11c and 12c via the first supply flow path 70; , Pressurizing air through the gas flow path 11 A pressurized air supply unit 20 that can be supplied to 12d and 13d via the second supply flow path 80, and a first supply flow path 70 that shuts off the first supply flow path 70 and a liquid flow path 11c The exhaust gas purification apparatus 1 includes a switching valve 40 that can be held at a first position X for releasing the atmosphere 12c or a second position Y for communicating the first supply flow path 70. When X is held, urea water in the liquid channels 11c and 12c opened to the atmosphere by the pressurized air supplied from the pressurized air supply unit 20 to the mixing channel 13c is upstream of the liquid channels 11c and 12c. When the switching valve 40 is held at the second position Y, the pressurized air and urea supplied from the pressurized air supply unit 20 to the mixing channel 13c are pushed. Mixed from the water supply unit 30 In which the urea water supplied to the flow path 13c is injected into the interior of the exhaust pipe 6 from mixed with injection port 13e.

  With this configuration, when the position of the switching valve 40 is switched to the first position X, the supply of urea water to the liquid flow paths 11c and 12c of the urea water supply nozzle 10 is stopped and the urea water supply nozzle Ten liquid flow paths 11c and 12c are released to the atmosphere. As a result, the pressurized air supplied to the gas flow paths 11 d, 12 d, and 13 d of the urea water supply nozzle 10 is injected from the urea water supply nozzle 10 that is the most downstream side of the liquid flow paths 11 c and 12 c of the urea water supply nozzle 10. It flows into the liquid flow paths 11c and 12c of the urea water supply nozzle 10 from the vicinity of the mouth 13e, and the urea water in the liquid flow paths 11c and 12c of the urea water supply nozzle 10 and the urea water supply nozzle 10 and the switching valve 40. The urea water inside the flow path 73 that constitutes a part of the first supply flow path 70 that connects to is discharged to the outside of the exhaust pipe 6 via the switching valve 40. That is, the urea water remaining inside the urea water supply nozzle 10 can be discharged from the inside of the urea water supply nozzle 10 without being discharged into the exhaust pipe 6. Thereby, unnecessary ammonia is not generated and released from the exhaust pipe 6 into the atmosphere. Further, urea does not precipitate inside the exhaust pipe 6 to clog the NOx catalyst 90, and urea does not adhere to the surface of the NOx catalyst 90, thereby reducing the catalyst performance. In addition, since pressurized air flows in from the vicinity of the injection port 13e which is the most downstream side of the liquid flow paths 11c and 12c of the urea water supply nozzle 10, the liquid flow paths 11c and 12c arranged in an upward gradient are also added. The urea water can be discharged without discharging only the compressed air.

The automatic supply valve is provided in the second supply flow path 80 and includes a pressurized air valve 23 that communicates or blocks the second supply flow path 80, and opens and closes the switching valve 40 and the pressurized air valve 23 by a control signal. It comprises a certain solenoid valve, and includes a control unit 60 for controlling the switching valve 40 and the pressurized air valve 23. The control unit 60 has passed a predetermined time after switching the switching valve 40 from the second position Y to the first position X. The second supply flow path 80 is blocked later by the pressurized air valve 23.

  With this configuration, in addition to the above-described effects, even if the supply of urea water is stopped, pressurized air is supplied to the urea water supply nozzle 10 for a predetermined time. As a result, since the pressurized air flows into the liquid flow paths 11c and 12c of the urea water supply nozzle 10, the urea water remaining in the urea water supply nozzle 10 is not discharged into the exhaust pipe 6. The urea water supply nozzle 10 can be discharged from the inside.

DESCRIPTION OF SYMBOLS 1 Exhaust purification device 2 Engine 6 Exhaust pipe 10 Urea water supply nozzle 11c Liquid flow path 11d Gas flow path 12c Liquid flow path 12d Gas flow path 13d Gas flow path 13e Injection port 20 Pressurized air supply part 30 Urea water supply pump 40 Switching Valve 70 First supply flow path 80 Second supply flow path X First position Y Second position

Claims (2)

The liquid flow path to which urea water is supplied, the gas flow path to which pressurized air is supplied, and the liquid flow path and the gas flow path are connected to the upstream side, and the downstream side has a smaller diameter than the upstream side. An injection port is formed at a downstream end of the mixed oil passage, and the urea water supplied to the liquid passage and the pressurized air supplied to the gas passage are mixed. A urea water supply nozzle that is mixed in the flow path and can be injected into the exhaust pipe connected to the internal combustion engine from the injection port;
Urea water supply unit capable of supplying urea water to the liquid channel via the first supply channel;
A pressurized air supply unit capable of supplying pressurized air to the gas flow path via a second supply flow path;
A switch that is provided in the first supply channel and that can be held at a first position that blocks the first supply channel and opens the liquid channel to the atmosphere, or a second position that allows the first supply channel to communicate with each other. A valve,
An exhaust purification device comprising :
When the switching valve is held at the first position, the urea water in the liquid channel released to the atmosphere by the pressurized air supplied from the pressurized air supply unit to the mixing channel is liquid. Pushed toward the upstream of the flow path and discharged out of the exhaust pipe,
When the switching valve is held at the second position, the pressurized air supplied from the pressurized air supply unit to the mixing flow channel and the urea water supplied from the urea water supply unit to the mixing flow channel Are mixed and injected into the exhaust pipe from the injection port. A pressurized air valve provided in the second supply flow path for communicating or blocking the second supply flow path;
The switching valve and the pressurized air valve are constituted by an automatic valve that opens and closes by a control signal ,
A control unit for controlling the switching valve and the pressurized air valve;
The controller is
2. The exhaust emission control device according to claim 1, wherein the second supply flow path is blocked by the pressurized air valve after a predetermined time has elapsed since the switching valve was switched from the second position to the first position.

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