JP2016098710A - Urea water recovery system for internal combustion engine, internal combustion engine, and urea water recovery method for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an urea water recovery system and the like of an internal combustion engine capable of early starting injection of urea water from an urea water injection nozzle in starting an engine.SOLUTION: An urea water injection nozzle 30 is composed of a two-fluid mixing injection nozzle for mixing and injecting urea water U and air A, and an urea water recovery passage 50 is formed in a state of being branched from a first urea water supply passage 33a from an urea water supply device (solenoid control pump) 31 to the two-fluid mixing injection nozzle 30, and connected to an urea water tank 32 through a first opening/closing valve 51. In stopping an engine 10, the urea water U remaining in a second urea water supply passage 33b from the urea water tank 32 to the urea water supply device 31 or to a second opening/closing valve 33c disposed near the urea water supply device 31 is not returned to the urea water tank 32, and only the urea water U remaining in the first urea water supply passage 33a is returned to the urea water tank 32 through the urea water recovery passage 50 while keeping the first opening/closing valve 51 in an opened state.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a urea water recovery system for an internal combustion engine, an internal combustion engine, and a urea water recovery method for an internal combustion engine that can start the injection of urea water from a urea water injection nozzle at the time of engine startup at an early stage.

  In general, when a selective reduction catalyst device (SCR catalyst device) is used as an exhaust gas purification device for purifying nitrogen oxide (NOx) contained in exhaust gas of an internal combustion engine, NOx to the selective reduction catalyst device is used. In order to supply ammonia as the reducing agent, urea water is supplied into the exhaust gas. In this case, urea water is directly injected into the exhaust gas passing through the exhaust passage from the urea water injection nozzle provided in the exhaust passage.

  Then, in the case of this urea water injection, if the engine is stopped (key-off) and the urea water injection is stopped after the urea water injection is stopped, the urea water remains in the urea water supply path. The urea water is crystallized to produce a white product (urea crystals), and the urea water supply path is clogged by the white product, so that there is a concern that the injection of urea water during engine operation may be hindered.

  In order to prevent clogging of the urea water supply path, when the engine is stopped, the urea water supply pump rotates in the opposite direction to that when supplying urea water to the urea water injection nozzle, and urea water injection is performed from the urea water tank. An emptying control is performed to suck back the urea water remaining in the urea water supply path to the nozzle to the urea water tank.

  However, since this emptying control is performed when the engine is stopped, there is no urea water in the urea water supply path from the urea water tank to the urea water injection nozzle at the next engine start. The urea water is sucked up from the urea water tank, and the urea water supply path from the urea water tank to the urea water injection nozzle is filled with urea water, and the urea water can be injected into the exhaust passage at the minimum. It is necessary to pressurize to a specified pressure that is The distance between the urea water tank and the urea water supply device and between the urea water supply device and the urea water injection nozzle are often separated from each other, so the total length of the urea water supply path that needs to be filled with urea water is long. Become. For this reason, the time required for filling the urea water supply path with the urea water and pressurizing to the specified pressure becomes long, and it is not possible to start the urea water injection from the urea water injection nozzle at the time of starting the engine at an early stage. There is.

  Meanwhile, a tank for storing urea aqueous solution, a pump for pressurizing urea aqueous solution, a pressure control valve for controlling the pressure of compressed air, a sprayer for mixing and spraying urea aqueous solution and compressed air, and excess urea from the pump A urea water injection device including a vent line and a relief valve for returning an aqueous solution to a tank has been proposed (see, for example, Patent Document 1).

  This urea water jetting apparatus uses a two-fluid mixed jet nozzle that mixes and sprays the pressure-adjusted urea water by the liquid electromagnetic pump and the air pressure-adjusted by the pressure control valve.

JP 2009-52509 A

  The present invention has been made in view of the above, and its purpose is to reduce the time required for filling urea water into the urea water supply path at the time of engine start-up and pressurization to a specified pressure. It is an object of the present invention to provide a urea water recovery system for an internal combustion engine, an internal combustion engine, and a urea water recovery method for the internal combustion engine that can start the injection of urea water from the urea water injection nozzle at an early stage.

  In order to achieve the above object, a urea water recovery system for an internal combustion engine of the present invention is the urea water recovery system for an internal combustion engine that injects urea water from a urea water injection nozzle disposed in an exhaust passage of the internal combustion engine. The water injection nozzle is composed of a two-fluid mixed injection nozzle that mixes and injects urea water supplied from the urea water supply device and air supplied from the air supply device. A controller for controlling the urea water recovery system provided with a urea water recovery path that branches from the first urea water supply path to the fluid mixing jet nozzle and is connected to the urea water tank via the first on-off valve However, when the internal combustion engine was stopped, it remained in the second urea water supply path from the urea water tank to the urea water supply device or to a second on-off valve provided in the vicinity of the urea water supply device. Without returning the raw water to the urea water tank, the first on-off valve is opened and only the urea water remaining in the first urea water supply path passes through the urea water recovery path to the urea. It is configured to perform control to return to the water tank.

  According to this configuration, the urea water injection nozzle is constituted by a two-fluid mixed injection nozzle that mixes and injects urea water and air, and uses the negative pressure generated by the air flow when injecting urea water. Since the urea water is injected while sucking out, the urea water is reduced to about 900 kPa (about 900 kPa) in order to reduce the injection particle size of the urea water as in the case of using a high pressure liquid injection nozzle that injects the urea water at a high pressure. It is not necessary to increase the pressure to about 9 bar), and the supply pressure of the urea water can be about 200 kPa (about 2 bar). As a result, when the engine is started, the time required to pressurize the urea water can be shortened, and the urea water injection from the urea water injection nozzle can be started early.

  Further, when the engine is stopped, when the first on-off valve is opened and the urea water is sucked back into the urea water tank, only the urea water remaining in the first urea water supply path is sucked back into the urea water tank. The urea water remaining in the second urea water supply path remains without being sucked back into the urea water tank. As a result, at the time of the next engine start, the time required for filling the first urea water supply path with the urea water and pressurizing to the specified pressure is required, but the urea water to the second urea water supply path is required. Therefore, the injection of urea water from the urea water injection nozzle can be started at an early stage as the time until the start of injection.

  In addition, when the engine is stopped, urea water is sucked back in the first urea water supply path on the urea water injection nozzle side which is likely to be clogged, so that it is possible to prevent accumulation of white product derived from urea water in the urea water injection nozzle, Clogging of the urea water injection nozzle can be prevented. Therefore, urea water can be reliably supplied to the exhaust passage during engine operation.

  In the urea water recovery system for an internal combustion engine described above, if the urea water supply device is constituted by a solenoid control pump, the urea water cannot pass through the solenoid control pump when the solenoid control pump is stopped. An on-off valve can be dispensed with.

  Since urea water containing air does not have to return from the first urea water supply path to the second urea water supply path, the urea water supply device is not a solenoid control pump, but a conventional urea. When the water pump is provided, the second urea water supply path near the urea water pump is separately provided with a second on-off valve that is opened only when urea water is injected into the exhaust passage. Although the same operation effect as the case where a solenoid control pump is provided can be obtained, in this case, a urea water pump and an on-off valve are required, and the number of parts increases.

  This solenoid control pump performs the operation of sucking urea water from the urea water tank and pressurizing and discharging the urea water only when the urea water is discharged and supplied to the two-fluid mixing and injection device. Like the urea water pump, even when the operation is stopped, the problem of air mixing does not occur in the urea water in the second urea water supply path from the urea water tank to the solenoid control pump. For this reason, it is not necessary to suck back urea water as in the case of the urea water pump of the prior art, and the time to pressurization of urea water can be shortened.

  The use of a two-fluid mixing injection nozzle makes it possible to make the injection particle size of urea water smaller than 20 μm even at a discharge pressure that can be generated by a solenoid-controlled pump. It becomes possible to adopt a solenoid control pump that can

  In the urea water recovery system for an internal combustion engine, the two-fluid mixed injection device is provided at the discharge port of the solenoid control pump, and the solenoid control pump and the two-fluid mixed injection device are integrated. The flow path between the pump and the nozzle can be shortened, and the time until the start of reinjection of urea water can be further shortened.

  Further, in the urea water recovery system for an internal combustion engine described above, the urea water recovery path or the first branch is branched from the air supply path from the air supply device to the two-fluid mixed injection nozzle, via a third on-off valve. An auxiliary air supply path connected to the first urea water supply path, and when the internal combustion engine is stopped, the controller supplies the urea water recovery path from the air supply apparatus via the auxiliary air supply path. When configured to supply air to the first urea water supply path, the following effects can be obtained.

  According to this configuration, when the engine is stopped, the air supplied from the air supply device flows into the first urea water supply path via the air auxiliary supply path, and remains in the first urea water supply path. Since the urea water is returned to the urea water tank via the urea water recovery path, the urea water remaining in the first urea water supply path can be reliably returned to the urea water tank.

  An internal combustion engine of the present invention for achieving the above object is configured to include the urea water recovery system for the internal combustion engine, and has the same effects as the urea water recovery system for the internal combustion engine. it can.

  Further, the urea water recovery method for an internal combustion engine of the present invention for achieving the above object is a urea water recovery method for an internal combustion engine in which urea water is injected from a urea water injection nozzle disposed in an exhaust passage of the internal combustion engine. The urea water is injected into the exhaust passage of the internal combustion engine by a two-fluid mixed injection nozzle that mixes and injects urea water supplied from the urea water supply device and air supplied from the air supply device, and supplies the urea water Branching from a first urea water supply path from the apparatus to the two-fluid mixed injection nozzle, providing a urea water recovery path connected to a urea water tank, and providing a first on-off valve in the urea water recovery path; When the internal combustion engine is stopped, the urea water remaining in the second urea water supply path from the urea water tank to the urea water supply device or to a second on-off valve provided in the vicinity of the urea water supply device is removed from the urea water. Water tank Without opening the first on-off valve, and only the urea water remaining in the first urea water supply path is returned to the urea water tank via the urea water recovery path. It is a method to do.

  Further, in the above urea water recovery method for an internal combustion engine, the urea water supply device is constituted by a solenoid control pump, and the urea water recovery is branched from the air supply path from the air supply device to the two-fluid mixed injection nozzle. An air auxiliary supply path connected to the path or the first urea water supply path, and when the internal combustion engine is stopped, a third on-off valve provided in the air auxiliary supply path is opened, and air is supplied to the air A supply device supplies the urea water recovery path or the first urea water supply path via the air auxiliary supply path.

  According to these methods, the same effects as the urea water recovery system for the internal combustion engine can be obtained.

  According to the urea water recovery system for an internal combustion engine, the internal combustion engine, and the urea water recovery method for the internal combustion engine of the present invention, the urea water injection nozzle is constituted by a two-fluid mixed injection nozzle that mixes and injects urea water and air. Therefore, when injecting urea water, it is injected while sucking out urea water using the negative pressure generated by the air flow, so the pressure for minimizing the urea water injection particle size can be low, so the engine At the time of start-up, the time required for pressurizing the urea water can be shortened, and the urea water injection from the urea water injection nozzle can be started early.

  Further, since the urea water remaining in the second urea water supply path remains without being sucked back into the urea water tank when the engine is stopped, the urea water to the second urea water supply path is next started. Is no longer necessary, and only the time required to fill the first urea water supply path with the urea water and pressurize to a pressure at which injection is possible is achieved. This also shortens the time until the start of injection. .

  In addition, when the engine is stopped, urea water is sucked back in the first urea water supply path on the urea water injection nozzle side which is likely to be clogged, so that it is possible to prevent accumulation of white product derived from urea water in the urea water injection nozzle, Clogging of the urea water injection nozzle can be prevented. Therefore, it is possible to reliably supply urea water to the exhaust passage during engine operation.

It is a figure showing typically composition of urea water recovery system of an internal-combustion engine of an embodiment concerning the present invention. It is a figure which shows typically an example of a structure of a two-fluid mixing injection nozzle.

  DESCRIPTION OF EMBODIMENTS Hereinafter, a urea water recovery system, an internal combustion engine, and a urea water recovery method for an internal combustion engine according to embodiments of the present invention will be described with reference to the drawings. The internal combustion engine of the embodiment according to the present invention is configured to include the urea water recovery system of the internal combustion engine of the embodiment according to the present invention, and has the same effects as the urea water recovery system of the internal combustion engine. Can play.

  First, an engine (internal combustion engine) 10 in which a urea water recovery system 1 for an internal combustion engine according to an embodiment of the present invention is arranged will be described with reference to FIG. In this engine 10, fresh air A introduced from the outside is pressurized by the compressor 14 b of the turbocharger 14, and exhaust gas (EGR gas) flowing into the intake passage 12 from an EGR passage (not shown) as necessary. Is sent to the cylinder of the engine body 11. Further, the exhaust gas G generated in this cylinder flows out into the exhaust passage 13, a part of which flows as EGR gas into the EGR passage, and the remaining exhaust gas G passes through the turbine 14a before being exhaust gas purification device. After being purified by flowing into the exhaust gas 20, the exhaust gas Gc that has been purified is discharged into the atmosphere via a muffler (not shown). In the configuration of FIG. 1, the exhaust gas purification device 20 includes an oxidation catalyst device (DOC) 21, a particulate collection device 22, a selective reduction catalyst device (SCR) 23, and the like.

  The urea water injection nozzle 30 disposed on the upstream side of the selective catalytic reduction device 23 is a device that injects urea water U for NOx reduction into the exhaust passage 13, and the injected urea water U is decomposed. Ammonia is generated, and NOx in the exhaust gas G is reduced to water and nitrogen by the selective reduction catalyst device 23 using this ammonia to render it harmless.

  The fuel injection nozzle 24 disposed on the upstream side of the oxidation catalyst device 21 is a device for injecting light oil (unburned fuel Fs into the exhaust passage 13), and during the regeneration processing of the particulate collection device 22, the exhaust passage 13 injects the light oil Fs, raises the temperature of the exhaust gas G by the oxidation heat of the light oil Fs oxidized by the oxidation catalyst device 21, and raises the temperature of the particulate collection device 22 to a temperature range where PM combustion is possible. It has a role to burn and remove the generated PM.

  The urea water recovery system 1 for an internal combustion engine according to the embodiment of the present invention is a urea water recovery system 1 for an internal combustion engine that injects urea water U from a urea water injection nozzle 30 disposed in an exhaust passage 13 of the engine 10. As shown in FIG. 2, the urea water injection nozzle 30 is connected to a urea water U supplied from a urea water tank 32 via a urea water supply path 33 from a solenoid control pump 31 which is a urea water supply device. In addition, a two-fluid mixed injection nozzle that mixes air Ap supplied from an air pump (not shown) or the like from an air pump 34 that is an air supply device via an air supply path 35 and injects the mixed fluid M is configured. .

  And in this invention, it branches from the 1st urea water supply path | route 33a from the urea water supply apparatus 31 to the two-fluid mixing injection nozzle 30, and is connected to the urea water tank 32 via the 1st on-off valve 51. A urea water recovery path 50 is provided.

  When the urea water supply device 31 is constituted by a solenoid control pump, the urea water U cannot pass through the solenoid control pump when the solenoid control pump is stopped, so that the second on-off valve 33c is unnecessary. can do. That is, when a conventional urea water pump is used as the urea water supply device 31 instead of the solenoid control pump, the second on-off valve 33c is provided in the vicinity of the urea water supply device 31. When the solenoid control pump 31 is employed, the second on-off valve 33c is unnecessary. Hereinafter, the case where a solenoid control pump is employed as the urea water supply device 31 will be mainly described.

  The solenoid control pump 31 operates to suck urea water U from the urea water tank 32 and pressurize and discharge the urea water U only when the urea water U is discharged and supplied to the two-fluid mixing injection nozzle 30. Therefore, even when the operation is stopped as in the conventional urea water pump, the urea water U in the second urea water supply path 33b from the urea water tank 32 to the solenoid control pump 31 is not mixed with air. There is no problem. Therefore, since the urea water U does not need to be sucked back like the conventional urea water pump, the time until the urea water U is pressurized can be shortened.

  The use of the two-fluid mixing injection nozzle 30 enables the injection particle size of the urea water U to be smaller than 20 μm even at the discharge pressure that can be generated by the solenoid control pump 32. The solenoid control pump 31 that can eliminate the passage can be employed.

  Moreover, as shown in FIG. 1, the control apparatus 40 which controls the urea water collection | recovery system 1 of the internal combustion engine of this invention is provided. The control device 40 controls the supply flow rate of urea water U and the supply flow rate of air Ap to the two-fluid mixing injection nozzle 30 by controlling the solenoid control pump 31 and the air pump 34 according to the operating state of the engine 10. It is a device to do. In addition, the control device 40 normally controls the engine 10 and the vehicle as a whole based on information on various sensors provided in the engine 10 or information on various sensors provided in the vehicle on which the engine 10 is mounted. However, it may be provided independently of the engine control unit.

  The control device 40 does not return the urea water U remaining in the second urea water supply path 33b from the urea water tank 32 to the solenoid control pump 31 to the urea water tank 32 when the engine 10 is stopped. The first on-off valve 51 is opened, and only the urea water U remaining in the first urea water supply path 33 a is controlled to return to the urea water tank 32 via the urea water recovery path 50.

  When a conventional urea water pump is adopted as the urea water supply device 31 instead of the solenoid control pump 31, the second on-off valve 33 c is closed when the engine 10 is stopped, and the urea water tank 32 starts to remove urea. Without returning the urea water U remaining in the second urea water supply path 33b to the water supply apparatus 31 to the urea water tank 32, the first on-off valve 51 is opened, and the first urea water supply path 33a. Then, control is performed to return only the remaining urea water U to the urea water tank 32 via the urea water recovery path 50. Thereby, the urea water U in the urea water pump as the urea water supply device 31 is also returned to the urea water tank 32.

  Thus, the urea water injection nozzle 30 is composed of a two-fluid mixed injection nozzle that mixes and injects the urea water U and the air Ap, and the negative pressure generated by the flow of the air Ap when the urea water U is injected. Since the urea water U is injected while sucking out the urea water U, in order to reduce the injection particle size of the urea water U as in the case of using a high pressure liquid injection nozzle that injects the urea water U at a high pressure, the urea water There is no need to increase the pressure of U to about 900 kPa (about 9 bar), and the supply pressure of urea water U can be about 200 kPa (about 2 bar). As a result, when the engine is started, the time required for pressurizing the urea water U can be shortened, and the injection of the urea water U from the urea water injection nozzle 30 can be started early.

  In addition, when the engine is stopped, when the first on-off valve 51 is opened and the urea water U is sucked back into the urea water tank 32, only the urea water U remaining in the first urea water supply path 33a is the urea water tank. 32 sucked back. On the other hand, the urea water U remaining in the second urea water supply path 33 b remains without being sucked back into the urea water tank 32. As a result, at the time of the next engine start, the time required to fill the first urea water supply path 33a with the urea water U and pressurize to the specified pressure is required, but to the second urea water supply path 33b. Therefore, it is possible to start the injection of the urea water U from the urea water injection nozzle 30 at an early stage.

  Further, since the urea water U is sucked back in the first urea water supply path 33a on the urea water injection nozzle 30 side that is likely to be clogged when the engine is stopped, the urea water-derived white product is accumulated in the urea water injection nozzle 30. It is possible to prevent the urea water injection nozzle 30 from being clogged. Therefore, the urea water U can be reliably supplied to the exhaust passage 13 during engine operation.

  And it is preferable to comprise the solenoid control pump 32 and the two-fluid mixing injection nozzle 31 integrally. The conventional high-pressure liquid injection nozzle has a length of 45 mm, a width of 60 mm, and a length of about 65 mm, while the solenoid control pump 32 has a diameter of about 30 mm to 40 mm and a length of about 80 mm to 90 mm. The mixed injection nozzle 31 has a diameter of about 20 mm to 30 mm, a length of 40 mm to 50 mm, and is a small device. Therefore, the solenoid control pump 32 and the two-fluid mixed injection nozzle are integrated by integrating both devices. The flow path between 31 can be shortened, and the time until the start of reinjection of the urea water U can be further shortened.

  Furthermore, it branches from the air supply path 35 from the air pump 34 to the two-fluid mixing injection nozzle 30, and via the third on-off valve 53, the urea water recovery path 50 or the first urea water supply path 33a (configuration in FIG. 1). Then, an air auxiliary supply path 52 connected to the urea water recovery path 50) is provided.

  At the same time, the control device 40 is configured to supply the air Ap from the air pump 34 to the urea water recovery path 50 or the first urea water supply path 33a via the air auxiliary supply path 52 when the engine 10 is stopped. . The supply of the air Ap is performed so that the return of the urea water U in the urea water recovery path 50 or the first urea water supply path 33a to the urea water tank 32 is promoted by the inflow of air.

  Thus, when the engine 10 is stopped, the air Ap supplied from the air pump 34 is caused to flow into the first urea water supply path 33a via the air auxiliary supply path 52, and the first urea water supply path 33a. Since the remaining urea water U is returned to the urea water tank 32 via the urea water recovery path 50, the urea water U remaining in the first urea water supply path 33a can be reliably returned to the urea water tank 32. become.

  Next, a urea water recovery method for an internal combustion engine according to an embodiment of the present invention will be described. This urea water recovery method for an internal combustion engine is a urea water recovery method for an internal combustion engine in which urea water U is injected from a urea water injection nozzle 30 disposed in the exhaust passage 13 of the engine 10. Water U is injected by a two-fluid mixing injection nozzle that mixes and injects urea water U supplied from urea water supply device 31 and air Ap supplied from air supply device 34.

  At the same time, a urea water recovery path 50 branched from the first urea water supply path 33a from the urea water supply device 31 to the two-fluid mixing injection nozzle 30 and connected to the urea water tank 32 is provided. A first on-off valve 51 is provided in the path 50.

  When the engine 10 is stopped, the urea remaining in the second urea water supply path 33b from the urea water tank 32 to the urea water supply device 31 or to the second on-off valve 33c provided in the vicinity of the urea water supply device 31. Without returning the water U to the urea water tank 32, the first on-off valve 51 is opened, and only the urea water U remaining in the first urea water supply path 33a passes through the urea water recovery path 50 to form urea. Return to water tank 32.

  Further, in the urea water recovery method for the internal combustion engine, the urea water supply device 31 is configured by a solenoid control pump, and is branched from the air supply path 35 from the air pump 34 to the two-fluid mixed injection nozzle 30 to be a urea water recovery path 50. Alternatively, an air auxiliary supply path 52 connected to the first urea water supply path 33a is provided, and when the engine 10 is stopped, the third on-off valve 53 provided in the air auxiliary supply path 52 is opened, and the air Ap is supplied to the air pump. 34 is supplied to the urea water recovery path 50 or the first urea water supply path 33a via the air auxiliary supply path 52, and the air Ap inside the urea water recovery path 50 and the first urea water supply path 33a. It is preferable to promote the return of the urea water U to the urea water tank 32.

  According to the urea water recovery system 1 for an internal combustion engine, the internal combustion engine, and the urea water recovery method for an internal combustion engine configured as described above, the two-fluid mixing in which the urea water injection nozzle 30 mixes and injects the urea water U and the air Ap. In order to make the injection particle size of urea water U small, since it is constituted by an injection nozzle and injecting urea water U using the negative pressure generated by the flow of air Ap when injecting urea water U Therefore, the time required for pressurization of the urea water U can be shortened when starting the engine, and the injection of the urea water U from the urea water injection nozzle 30 can be started at an early stage.

  Further, since the urea water U remaining in the second urea water supply path 33b remains without being sucked back into the urea water tank 32 when the engine is stopped, the second urea water supply is performed at the next start of the engine 10. The filling of the urea water U into the path 33b becomes unnecessary, and only the time necessary to fill the first urea water supply path 33a with the urea water U and pressurize it to a pressure that can be injected is used. The time until the start of injection can be shortened. Therefore, in the urea water recovery system 1 for an internal combustion engine of the present invention, it can be shortened by about 30 to 50 seconds as compared with the prior art.

  Further, when the engine 10 is stopped, the urea water U is sucked back in the first urea water supply path 33a on the urea water injection nozzle 30 side that is likely to be clogged. Therefore, a white product derived from urea water in the urea water injection nozzle 30 And the clogging of the urea water injection nozzle 30 can be prevented. Therefore, the urea water U can be reliably supplied to the exhaust passage 13 during operation of the engine 10.

1 Urea water recovery system for internal combustion engine 10 Engine (internal combustion engine)
11 Engine body 12 Intake passage 13 Exhaust passage 14 Turbocharger (turbo-type supercharger)
14a Turbine 14b Compressor 20 Exhaust gas purification device 21 Oxidation catalyst device (DOC)
22 Fine particle collecting device 23 Selective reduction type catalyst device 24 Fuel injection device 30 Urea water injection nozzle (two-fluid mixing injection nozzle)
31 Solenoid control pump (urea water supply device)
32 urea water tank 33 urea water supply path 33a first urea water supply path 33b second urea water supply path 33c second on-off valve 34 air pump (air supply device)
35 Air supply path 40 Control device 50 Urea water recovery path 51 First on-off valve 52 Air auxiliary supply path 53 Third on-off valve A Fresh air Ap Air (compressed air, pressurized air)
U Urea water M Mixed fluid G Generated exhaust gas Gc Purified exhaust gas

Claims (7)

In a urea water recovery system for an internal combustion engine that injects urea water from a urea water injection nozzle disposed in an exhaust passage of the internal combustion engine,
The urea water injection nozzle is composed of a two-fluid mixed injection nozzle that mixes and injects urea water supplied from a urea water supply device and air supplied from an air supply device,
A urea water recovery path branched from the first urea water supply path from the urea water supply device to the two-fluid mixed injection nozzle and connected to the urea water tank via the first on-off valve is provided;
When the internal combustion engine is stopped, the control device for controlling the urea water recovery system includes a second controller from the urea water tank to the urea water supply device or a second on-off valve provided in the vicinity of the urea water supply device. Without returning the urea water remaining in the urea water supply path to the urea water tank, the first on-off valve is opened to recover only the urea water remaining in the first urea water supply path. A urea water recovery system for an internal combustion engine configured to perform control to return to the urea water tank via a path.   The urea water recovery system for an internal combustion engine according to claim 1, wherein the urea water supply device includes a solenoid control pump.   The urea water recovery of the internal combustion engine according to claim 1 or 2, wherein the two-fluid mixed injection nozzle is provided at a discharge port of the solenoid control pump, and the solenoid control pump and the two-fluid mixed injection nozzle are integrated. system. An air auxiliary supply path branched from the air supply path from the air supply device to the two-fluid mixed injection nozzle and connected to the urea water recovery path or the first urea water supply path via a third on-off valve And providing
The control device is configured to supply air from the air supply device to the urea water recovery path or the first urea water supply path via the air auxiliary supply path when the internal combustion engine is stopped. The urea water recovery system for an internal combustion engine according to any one of claims 1 to 3.   An internal combustion engine comprising the urea water recovery system for an internal combustion engine according to any one of claims 1 to 4. In a urea water recovery method for an internal combustion engine in which urea water is injected from a urea water injection nozzle disposed in an exhaust passage of the internal combustion engine,
The urea water is injected into the exhaust passage of the internal combustion engine by a two-fluid mixed injection nozzle that mixes and injects urea water supplied from the urea water supply device and air supplied from the air supply device, and supplies the urea water Branching from a first urea water supply path from the apparatus to the two-fluid mixed injection nozzle, providing a urea water recovery path connected to a urea water tank, and providing a first on-off valve in the urea water recovery path;
When the internal combustion engine is stopped, the urea water remaining in the second urea water supply path from the urea water tank to the urea water supply device or to a second on-off valve provided in the vicinity of the urea water supply device is removed from the urea water. Without returning to the water tank, the first on-off valve is opened, and only the urea water remaining in the first urea water supply path is returned to the urea water tank via the urea water recovery path. A method for recovering urea water of an internal combustion engine, characterized by: The urea water supply device is constituted by a solenoid control pump,
Providing an air auxiliary supply path that branches from the air supply path from the air supply device to the two-fluid mixed injection nozzle and connects to the urea water recovery path or the first urea water supply path;
When the internal combustion engine is stopped, a third on-off valve provided in the air auxiliary supply path is opened, and air is supplied from the air supply device via the air auxiliary supply path to the urea water recovery path or the first. The urea water recovery method for an internal combustion engine according to claim 6, wherein the urea water supply path is supplied to one urea water supply path.

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