JP2008291678A - Reducing agent feeding apparatus - Google Patents

Abstract

An object of the present invention is to prevent a reducing agent from remaining in a pump portion that pumps the reducing agent when a state in which the reducing agent is not supplied to a catalyst device such as an engine stop is continued.
An engine exhaust passage 11 includes a urea water tank 21 that stores urea water, and a urea water pump 22 that is accommodated in the urea water tank 21 and pumps the urea water out of the urea water tank. In the urea water supply device that supplies urea water pumped from the urea water pump 22 through the urea water supply pipe 23 to the upstream side of the SCR catalyst 13, the relative position of the urea water pump 22 with respect to the urea water tank 21 is A pump position adjusting member 29 is provided for moving the urea water in the liquid surface direction in which the liquid surface is displaced.
[Selection] Figure 1

Description

  The present invention relates to a reducing agent supply device, and is suitable for application to a selective reduction catalyst device that uses urea water as a reducing agent, for example, in an exhaust purification device of an internal combustion engine.

In an internal combustion engine such as a diesel engine applied to an automobile or the like, a urea SCR device has been developed as an exhaust purification device that purifies NOx (nitrogen oxide) in exhaust gas at a high purification rate, and urea water is used as a reducing agent. The one to be used has been proposed (see Patent Document 1). Note that SCR is an abbreviation for Selective Catalytic Reduction and is called a selective reduction catalyst denitration apparatus. Urea SCR device, sprayed urea water into NO and NO ₂ contained in the exhaust gas, by decomposing the NOx into _{N 2} and _{H 2} O, is intended to purify NOx in the exhaust.

  In the technique disclosed in Patent Document 1, a urea water tank that stores urea water and a feed pump that pumps urea water are provided, and the urea water pumped by the feed pump is mixed with a mixed gas of urea water and exhaust gas. Supplied to a catalyst device that purifies exhaust gas.

The feed pump is divided into a diaphragm type pump unit and a motor that drives the pump unit via a tappet. By driving with the motor, the pump unit sucks urea water from the urea water tank, It is pumped to the catalyst device via a route such as a pipe through which water flows.
Japanese translation of PCT publication No. 2004-510093

  In the prior art disclosed in Patent Literature 1 and the like, urea water to the catalyst device is not interrupted by the pumping of the pump unit, but there is a possibility that the urea water may be clogged in the route such as the pipe. That is, since the urea water is a mixed solution of the urea component and the water component, it is frozen at about −11 ° C. at low temperature in the atmosphere. Since the urea water volume increases by about 7% by freezing, there is a problem that the path is damaged or the pumping function of the pump unit is impaired.

  In view of this, the inventors have examined the use of a turbine pump capable of sucking up and sucking back fluid such as urea water as the pump unit. By applying such a pump unit to a conventional urea water supply device, for example, after the engine is stopped, it is possible to reversely rotate the pump unit and suck the urea water in the urea supply device back into the urea water tank. . However, because of the turbine type pump, urea water remains in the pump portion even after the water returning operation, and there is still a possibility that the pump portion itself is damaged due to freezing of the urea water remaining in the pump portion. In addition, if a reducing agent such as urea water is always left in the pump unit, the reducing agent having corrosiveness may cause oxidative corrosion of the pump unit itself.

  The present invention has been made in consideration of such circumstances, and its purpose is to reduce the reducing agent to a pump unit that pumps the reducing agent when the state in which the reducing agent is not supplied to the catalyst device, such as when the engine is stopped, continues. The purpose is to prevent residue.

  In order to achieve the above object, the present invention comprises the following technical means.

  That is, in the invention described in claims 1 to 13, a reducing agent tank that stores a liquid reducing agent, a pump that is housed in the reducing agent tank, and that pumps the reducing agent in the reducing agent tank out of the reducing agent tank; A reducing agent supply device that supplies a reducing agent that is pumped from the pump through the reducing agent passage to an upstream side of the exhaust gas purification catalyst in the exhaust passage of the internal combustion engine. Pump position adjusting means for moving the position in the liquid surface direction in which the liquid surface of the reducing agent is displaced is provided.

  In order to discharge the liquid reducing agent remaining in the pump, there is provided a pump position adjusting means for moving the relative position of the pump with respect to the reducing agent tank in the liquid surface direction where the liquid surface of the reducing agent is displaced. For example, the relative position of the pump can be moved to a position where the suction port side of the pump is not immersed in the reducing agent. In this way, by moving the relative position of the pump in the liquid surface direction by the pump position adjusting means, it is possible to prevent the reducing agent from staying in the pump.

  Accordingly, the retention of the reducing agent in the pump is avoided, and therefore, damage to the pump itself that may be caused by freezing of the liquid reducing agent remaining in the pump can be prevented.

  Here, when the internal combustion engine is stopped, exhaust gas is not generated from the internal combustion engine, and therefore it is not necessary to supply a reducing agent to the exhaust gas purification catalyst. Therefore, the reducing agent below the liquid level is not sucked up from the suction port side of the pump.

  On the other hand, as in the second aspect of the present invention, there is provided stop detection means for detecting the stop of the internal combustion engine, and the pump position adjusting means is configured such that the pump is liquidated on condition that the internal combustion engine is stopped detected by the stop detection means. It is preferable to move in a direction away from the surface.

  According to this, the pump position adjusting means detects such a stop of the internal combustion engine, and moves the pump in a direction away from the liquid level on the condition of the detected stop of the internal combustion engine. It is possible to move to a set position that is always separated from the preset liquid level. Therefore, it is possible to avoid retention of the reducing agent in the pump in a relatively simple manner in order to prevent pump damage due to freezing of the reducing agent.

  In addition, the pump position adjusting means is an electric actuator that holds the pump and moves it in the liquid surface direction as in the invention described in claim 3.

  Thereby, as a pump position adjusting means, a combination of a screw shaft capable of axially moving a holding portion for holding the pump and moving in the liquid surface direction, for example, a pump, and a motor for rotating the shaft, or a cylinder An electric actuator such as a linear motor that directly drives a shaft such as a shaft can be used.

  Here, the reducing agent in the reducing agent tank is consumed in accordance with the supply to the exhaust gas purification catalyst, so that the liquid level of the reducing agent decreases according to the consumption amount, or the reducing agent is replenished into the reducing agent tank. The liquid level increases according to the amount.

  On the other hand, as in the invention described in claim 4, the pump position adjusting means includes a buoyant body that gives buoyancy to the held member, and the buoyant body sucks the reducing agent in the pump as the held member. The suction port side is held in a state of being immersed in the liquid surface.

  Accordingly, the pump position adjusting means is provided with a simple configuration such that the buoyancy body that gives buoyancy to the pump to the extent that the suction port side of the pump is immersed in the liquid level is mounted on the pump. Can do.

  Here, when the internal combustion engine is used for a vehicle such as an automobile, the stop of the internal combustion engine means a vehicle such as a case where an occupant leaves the vehicle or an idling stop for waiting for a signal before an intersection. When the vehicle is parked or temporarily stopped, the internal combustion engine is stopped.

  For example, in the method of directly detecting the stop of the internal combustion engine, there is a possibility that even when it is temporarily stopped, it is treated as a parking where the stop state continues. In such a temporary stop, moving the relative position of the pump by the pump position adjusting means is for exhaust purification by the pump in the pump pumping state after releasing the temporary stop (after starting the engine). There is a risk of disrupting the supply to the catalyst. Therefore, it is necessary to detect a driver operation event related to the driver's operation on the vehicle-related device and detect a stop of the internal combustion engine related to parking.

  On the other hand, as in the invention described in claim 5, the stop detection means detects an event that occurs before or after the internal combustion engine stops, and predicts a stop of the internal combustion engine based on the detected event. And a stop condition determination unit that determines that the condition is satisfied when the stop is predicted by the stop prediction unit.

  This makes it possible to detect a parking preparation state (parking brake ON state) in which the driver steps on a parking brake such as a side brake of the vehicle as an event that occurs before or after the internal combustion engine stops. The stop condition of the internal combustion engine determined by the stop condition determining means is the efficiency of stopping the internal combustion engine related to parking by detecting such a parking preparation state and predicting continuous stop, that is, parking by the stop predicting means. Can be detected automatically.

  Here, the liquid reducing agent is not necessarily frozen when the internal combustion engine is stopped. Although it is possible to move the relative position of the pump on the condition that the internal combustion engine is stopped, a power source such as a vehicle-mounted battery is used as a driving force generation source other than the internal combustion engine when the internal combustion engine is stopped. Therefore, it is necessary to avoid such wasteful consumption of energy such as electric energy.

  On the other hand, as in the sixth to seventh aspects of the invention, there is provided reducing agent temperature detecting means for detecting the temperature of the reducing agent, and the pump position adjusting means is a first condition as the condition (stop condition of the internal combustion engine). When the second condition is satisfied, where the second condition is that the temperature of the reducing agent is equal to or lower than the temperature at which the reducing agent is solidified, it is preferable to move the pump in a direction away from the liquid level.

  According to this, in addition to the first condition that the internal combustion engine is stopped, when the second condition that the temperature of the liquid reducing agent is equal to or lower than the solidifying temperature is satisfied, the pump is moved away from the liquid surface. Therefore, the driving force for moving the pump in the pump position adjusting means is consumed based on the prediction of the freezing of the reducing agent according to the temperature of the reducing agent. Therefore, it is possible to avoid consuming unnecessary driving force.

  In particular, the reducing agent temperature detecting means preferably detects the temperature of the reducing agent at a predetermined waiting time interval after the first condition is satisfied, as in the seventh aspect of the invention.

  As a result, since the temperature of the reducing agent is continuously detected at a predetermined waiting time interval while the internal combustion engine is stopped, that is, after the first condition is satisfied, the freezing of the reducing agent is predicted. The pump movement by the pump position adjusting means can be generated by preventing the pump from being damaged by freezing of the reducing agent by generating the driving force by the pump position adjusting means.

  Further, as in the invention described in claim 8, the pump has a suction portion for sucking the reducing agent from the outside, a pressure feeding mechanism for pumping the reducing agent flowing in through the suction portion, and a drive motor for driving the pressure feeding mechanism. The drive motor is capable of rotating in the rotation direction of the drive motor in a first direction in which the pumping mechanism pumps the reducing agent to the outside of the pump and in a second direction in which the pumping mechanism sucks the reducing agent from the outside of the pump. It is preferable.

  According to this, the pump can supply the reducing agent fed by pressure from the pump to the upstream side of the exhaust purification catalyst through the reducing agent passage by setting the rotation direction of the drive motor to the first direction. By reversing the rotation direction and setting the second direction, the reducing agent in the reducing agent passage can be sucked back to the pump side.

  That is, by driving the pump in a reducing agent sucking back state different from the reducing agent pumping state, the reducing agent in the reducing agent passage can be collected in the reducing agent tank through the pump.

  Moreover, in the invention described in claim 8, since the pump position adjusting means as described in any one of claims 1 to 7 is provided, the reducing agent in the reducing agent passage is reduced through the pump. After being collected in the tank, the reducing agent remaining in the pump can also be discharged into the reducing agent tank.

  Further, as in the invention described in claims 9 to 11, the pump, a holding wall member provided in the reducing agent tank for receiving and holding the pump inside, and any one of claims 1 to 8. It is preferable that the pump position adjusting means according to one aspect is provided with a connecting portion that connects the holding wall member.

  In general, a pump that sucks in a stored fluid such as a liquid reducing agent and pumps the fluid to the outside is generally equipped with a pump inlet side and a discharge port side in order to protect the functions of the pump itself and an external device to which the fluid is supplied. At least one of these is provided with a foreign substance removing device (filtering device). Therefore, the pump is configured as an assembly (module) in which members such as a foreign substance removing device (filtration device) are assembled. For example, when the pump position adjusting means directly holds the pump, an assembly (module) in which a member such as a foreign substance removing device (filtering device) is assembled is formed between the pump position adjusting means and the pump. May be difficult.

  On the other hand, in the invention according to the ninth to eleventh aspects, the pump is housed and held inside a holding wall member such as a cylindrical sub-tank, and the pump position adjusting means is connected to the holding wall member via a connecting portion. The structure is connected. In this way, the pump position adjusting means does not directly hold the pump, but the pump position adjusting means indirectly holds the pump via the holding wall member. Members constituting an assembly (module) such as a foreign substance removing device (filtering device) can be collectively assembled in the space formed therebetween.

  In particular, the holding wall member is a sub tank capable of storing a reducing agent therein as in the invention described in claim 10, and the sub tank includes a suction port for pumping the reducing agent outside the sub tank into the sub tank. Preferably it is.

  According to this, when the pump sucks the reducing agent in the sub tank and discharges it outside, it is possible to pump the reducing agent outside the sub tank into the sub tank through the suction port using the suction input generated in the pump. The reducing agent can be stored in the sub tank outside the sub tank, that is, separately from the reducing agent tank. Moreover, when the pump is stopped, the suction input of the pump is lost, so that the reducing agent in the sub tank is returned to the reducing agent tank through the suction port.

  That is, when the internal combustion engine is stopped, as a method of separating the pump from the liquid level, it is not necessary to directly separate the pump inlet side from the liquid surface of the reducing agent in the reducing agent tank, and the bottom of the sub tank is separated from the liquid level. An indirect method of pulling apart can be used.

  For example, by appropriately setting the size of the suction port, it is possible to adjust the time for returning the reducing agent accumulated in the sub tank to the reducing agent tank after the pump is stopped. Thereby, for example, even when the stop of the internal combustion engine is a temporary stop, at the start of the operation of the internal combustion engine, for the purpose of pumping using the reducing agent that temporarily remains in the sub tank after the pump stops driving The reducing agent can be sucked into the pump.

  Moreover, it is preferable to provide a jet pump provided in the sub tank and pumping the reducing agent outside the sub tank from the suction port into the sub tank.

  A jet pump generally constitutes an assembly (module) together with members such as a pump and a foreign substance removing device (filtering device), and a part of fluid discharged from the pump to the outside of the pump (for example, pressure of a regulator or the like) The negative pressure generated by the reflux flow that returns (returns) the fluid surplus when the pressure is adjusted by the regulating valve to the sub-tank is used as the fluid pumping force.

  On the other hand, in the invention according to the eleventh aspect, since such a jet pump is provided in the sub-tank, a part of the reducing agent discharged from the pump to the outside of the pump (for example, when adjusting the pressure with a regulator, it becomes redundant) The reducing agent outside the sub tank can be efficiently pumped into the sub tank from the suction port by using the negative pressure of the jet pump generated when the reducing agent is returned to the sub tank.

  Therefore, even when the pump position adjustment means temporarily pulls the pump away from the liquid level of the reducing agent when the internal combustion engine is stopped, for example, after the operation of the internal combustion engine is started, the bottom of the sub tank is placed in the reducing agent in the reducing agent tank. By simply moving the relative position of the pump by the pump position adjusting means to the extent that it is immersed in the liquid level, the reducing agent in the sub tank can be quickly stored by the jet pump that uses the flow of the reducing agent discharged by driving the pump. it can.

  According to a twelfth aspect of the present invention, after the internal combustion engine is stopped, the pump is provided with sucking back control means for driving a reducing agent sucking back state different from the reducing agent pumping state. It is preferable that the pump is moved in a direction away from the liquid surface, with the third condition that the control means is implemented.

  Thus, after the reducing agent in the reducing agent passage is collected in the reducing agent tank through the pump by the suck back control means, the reducing agent remaining in the pump is also discharged into the reducing agent tank by the pump position adjusting means. Can do. Therefore, it is possible to reliably prevent damage to the reducing agent passage and the pump due to freezing of the reducing agent.

  Further, as in the invention described in claim 13, the reducing agent is a urea aqueous solution, and the exhaust purification catalyst promotes an exhaust purification reaction for reducing NOx contained in the exhaust by ammonia generated from the urea aqueous solution. The reducing agent supply device according to any one of claims 1 to 12 is a pump that promotes the specific exhaust purification reaction based on the addition of the reducing agent in the exhaust purification catalyst. It is characterized in that the reducing agent pumped in is added and supplied into the exhaust passage.

  According to this, it is suitable to apply to a so-called urea SCR device that uses urea water as a reducing agent and promotes a specific exhaust purification reaction (NOx reduction reaction) of reducing NOx. In order to prevent damage to the pump due to freezing of urea water, urea water can be prevented from remaining in the pump.

  Hereinafter, an embodiment in which the reducing agent supply device of the present invention is applied to a urea water supply device of a urea SCR device will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic diagram showing the entire urea water SCR device to which the urea water supply device of the present embodiment is applied. FIG. 2 is a flowchart showing control for returning urea water collected in the urea water supply system together with urea water supply to the urea water tank in the urea water supply apparatus. FIG. 3 is a flowchart showing the position control of the urea water pump corresponding to the subroutine process executed in step 50 in FIG.

  FIG. 4 is a flowchart showing urea water suck-back control corresponding to the subroutine processing executed in step 30 in FIG. FIG. 5 is a schematic diagram showing a suck-back mode for recovering urea water. FIG. 6 is a cross-sectional view showing an example of the internal structure of the urea water pump.

  The reducing agent supply device (hereinafter referred to as urea water supply device) 20 of the present embodiment supplies urea water as a reducing agent into the exhaust pipe 11 upstream of the exhaust purification catalyst provided in the exhaust system of the internal combustion engine. Addition supply. Here, the addition supply is to atomize and inject the pressurized urea water with, for example, a urea water addition valve such as an injection valve, and to supply a mixed gas of urea water and exhaust gas to the exhaust gas purification catalyst.

  First, the exhaust purification apparatus in the present embodiment purifies NOx in exhaust using a selective reduction catalyst as the exhaust purification catalyst, and is constructed as a urea SCR apparatus as shown in FIG.

  As shown in FIG. 1, the urea SCR device can be broadly classified into exhaust gas discharged from a diesel engine (hereinafter referred to as an engine) mounted on an automobile. A system component, that is, a urea water supply device 20 and a control system component are configured.

  Specifically, an exhaust pipe 11 connected to an engine body (not shown) is provided as a component of the exhaust system, and the exhaust pipe 11 includes a DPF (Diesel Particulate Filter) 12 and a selective reduction catalyst (hereinafter referred to as SCR). Catalyst) 13. In addition, a urea water addition valve 15 for adding and supplying urea water (urea aqueous solution) into the exhaust pipe 11 is provided between the DPF 12 and the SCR catalyst 13 in the exhaust pipe 11.

Further, in the exhaust pipe 11, on the downstream side of the SCR catalyst 13, there is provided an exhaust sensor 16 in which both a NOx detector (NOx sensor) and an exhaust temperature detector (exhaust temperature sensor) are built. The amount of NOx in the exhaust gas (NOx purification rate by the SCR catalyst 13) and the temperature of the exhaust gas are detected on the downstream side. Further downstream of the exhaust pipe 11, an ammonia removal device (for example, an oxidation catalyst) for removing excess ammonia (NH ₃ ), an ammonia senna for detecting the amount of ammonia in the exhaust, and the like are required. Is provided.

  The DPF 12 is a continuous regeneration PM removal filter that collects PM (particulate matter) in exhaust gas. The DPF 12 carries a platinum-based oxidation catalyst and can remove HC and CO together with soluble organic matter (SOF) which is one of the PM components. Incidentally, the PM collected in the DPF 12 can be removed by combustion by post-injection after the main fuel injection in the engine (corresponding to the regeneration process of the PM removal filter), and thus the DPF 12 can be used continuously. .

The SCR catalyst 13 promotes a NOx reduction reaction (exhaust gas purification reaction).
4NO + 4NH ₃ + O ₂ → 4N ₂ + 6H ₂ O (Formula 1)
6NO ₂ + 8NH ₃ → 7N ₂ + 12H ₂ O (Formula 2)
NO + NO ₂ + 2NH ₃ → 2N ₂ + 3H ₂ O (Formula 3)
Such a reaction is promoted to reduce NOx in the exhaust gas. Then, an aqueous solution (hereinafter simply referred to as urea water) containing ammonia (NH ₃ ) that serves as a NOx reducing agent in these reactions is mixed with exhaust gas and supplied to the SCR catalyst 13. Specifically, the urea water is injected and supplied from the urea water addition valve 15 toward the exhaust gas flowing through the exhaust pipe 11 on the upstream side of the SCR catalyst 13.

  As shown in FIG. 1, the urea water supply device 20 includes a urea water supply unit 20a, a urea water supply pipe 23, and a urea water addition valve 15. The urea water supply unit 20a includes a urea water tank 21, urea A water pump 22 and a pump position adjusting member 29 are included. The details of the urea water supply unit 20a will be described later.

  The urea water addition valve 15 is a well-known fluid jet including a drive unit composed of an electromagnetic solenoid or the like and a valve unit having a valve member (for example, a needle) for opening and closing an injection hole as an addition port formed at the tip. The valve structure is configured to open and close based on a drive signal from an electronic control unit (hereinafter, ECU) 30. That is, when the electromagnetic solenoid is energized based on the drive signal from the ECU 30, the needle moves in the valve opening direction along with the energization, and the addition port is opened by the needle movement, and urea water is added (injected).

  In addition, the addition port should just be comprised in either one nozzle hole or several aggregate, ie, the aggregate | assembly (group nozzle hole) of many fine nozzle holes.

  The urea water supply pipe 23 is a urea water passage that connects the urea water addition valve 15 and the urea water pump 22 of the urea water supply unit 20a. The urea water supply pipe 23 includes a filter 24 as a filtration device for filtering the urea water, and a pressure adjustment valve (hereinafter referred to as a regulator) for adjusting the pressure of the urea water pumped by the urea water pump 22. Is provided. Therefore, the foreign water is removed from the urea water discharged from the urea water pump 22 by the filter 24, and then adjusted to a predetermined supply pressure by the regulator 25. As a result of adjusting the pressure of the urea water adjusted by the regulator 25, surplus urea water is returned (returned) to the urea water tank 21 through the return pipe 26.

  Here, in this embodiment, FIG. 1 shows an example in which only the urea water pump 22 is accommodated in the urea water tank 21, but the filter 24 and the regulator 25 include the following urea water pump unit ( It may be incorporated in a urea water pump module. That is, the filter 24 and the regulator 25 are accommodated in the urea water tank 21 together with the urea water pump 22, and the urea is formed as a unit (modularized) as an assembly including the urea water pump 22, the filter 24, and the regulator 25. It may constitute a water pump unit (urea water pump module).

  The urea water supply pipe 23 is provided with a pressure sensor 27 for detecting the pressure of the urea water in the urea water supply pipe 23 and a temperature sensor 28 for detecting the temperature of the urea water.

  The components of the control system include an ECU 30, an exhaust sensor 16, a pressure sensor 27, a temperature sensor 28, and a liquid level sensor for detecting the liquid level of urea water accumulated in a urea water tank 21 (not shown). It is comprised including. The ECU 30 includes a known microcomputer, and based on detection values of various sensors 16, 27, 28, various actuators such as a urea water pump 22, a urea water addition valve 15, a pump position adjusting member (pump position adjusting means) 29 and the like. Control the driving amount. The details of the control process executed in the ECU 30 based on the program will be described later.

In the urea SCR device according to this embodiment, during operation of the engine, the urea water in the urea water tank 21 is pumped to the urea water addition valve 15 through the urea water supply pipe 23 by driving the urea water pump 22 to add urea water. The urea water is added and supplied into the exhaust pipe 11 by the valve 15. Then, urea water is supplied to the SCR catalyst 13 together with the exhaust gas in the exhaust pipe 11, and the exhaust gas is purified by the NOx reduction reaction in the SCR catalyst 13. When reducing NOx, for example,
_{(NH2) 2 CO + H 2} O → 2NH 3 + CO 2 ··· ( Equation 4)
In this reaction, urea water is hydrolyzed by exhaust heat to produce ammonia (NH ₃ ), and this ammonia is added to the NOx in the exhaust selectively adsorbed by the SCR catalyst 13. Is done. The SCR catalyst 13 performs the reduction reaction based on the ammonia (the above reaction formulas (Formula 1) to (Formula 3)), whereby NOx is reduced and purified.

Next, the urea water supply part 20a is demonstrated according to FIG.1, FIG.4, FIG.5. The urea water tank 21 is configured by a closed container with a liquid supply cap (not shown), and urea water of a predetermined concentration is stored therein. As a countermeasure against freezing of urea water in the urea water tank 21, a heater is attached to the urea water tank 21 or a heat insulating material such as a heat insulating sheet is provided around the urea water tank 21 as necessary. I have to.

  As shown in FIG. 1, a urea water pump 22 is disposed in the urea water tank 21 and is immersed in urea water (hereinafter referred to as a first state in which urea water can be pumped). The arrangement state can be switched by the pump position adjusting member to the state separated from the liquid surface of the urea water (hereinafter, the second state where the urea water can be collected in the urea water tank 21).

  The urea water pump 22 in the present embodiment is a fluid pump having a well-known structure mounted on an automobile. For example, a so-called non-volumetric fluid pump that sucks and discharges (pressure feeds) fluid by rotating an impeller (turbine) in a pump casing. It is a pump. Since such a urea water pump 22 does not have a pump chamber whose volume changes like a positive displacement pump when the impeller stops rotating, the urea water sucked into the urea water pump 22 is stored in the urea water pump 22. Therefore, when the position of the urea water pump 22 is set to the second state, the urea water is drained from the suction port 22a of the urea water pump 22 to the urea water tank 21.

  The positive displacement pump is a trochoid gear type or roller type pump, and a plurality of volume chambers (pump chambers) are partitioned by a trochoid gear or roller in the pump casing, and the volume of the pump chamber is determined. The fluid is sucked and discharged (pumped) by change. In such a positive displacement pump, a pump partitioned by a partition member such as the trochoid gear or roller between a pump chamber connected to the suction port side and a pump chamber connected to the discharge port side in a plurality of pump chambers. Since the chamber is formed, the urea water is not smoothly drained to the urea water tank 21 even if the pump position is set to the second state.

  Here, also in the positive displacement pump, a method of enlarging the seal gap in the sealing function portion of the partition member, that is, a gap for sealing between the partition member and the pump casing (hereinafter referred to as a seal gap) can be considered. . Although it is possible to drain urea water into the urea water tank 21 by this method, the sealing function is impaired, and the pump discharge efficiency during pump operation (trochoid gear rotation) is reduced. In the pump, urea water is not smoothly drained when stopped.

  As shown in FIG. 6, the urea water pump 22 generates a driving force that drives the pressure feeding unit 42 so that the pressure feeding unit 42 pumps the urine water and the pressure feeding unit 42 as a pressure feeding mechanism that pumps the urea water. And a motor unit 43.

  The pressure feeding unit 42 is a non-positive displacement pump, and is a turbine pump including pump casings 44 and 45 and an impeller 47. In the pump casings 44 and 45, a pump chamber 46 is formed inside the mating surface of the upper case 44 and the lower case 45 by joining two members of the upper case 44 and the lower case 45. As a method for joining the two members, the upper case 44 and the lower case 45 are joined to one end portion of the housing 41 by press fitting, caulking, or the like.

  C-shaped pump passages 46 a are respectively formed on the mating surfaces of the upper case 44 and the lower case 45 that form the pump chamber 46. An impeller 47 fitted to the rotating shaft 56 of the drive motor unit 43 is rotatably accommodated in the pump chamber 46.

  In the lower case 45, a suction portion extends toward the downstream side of the urea water (downward in FIG. 6), and a suction port 22a for sucking the urea water is formed. Further, the upper case 44 has a discharge port (hereinafter referred to as a pressure feed unit discharge port) formed on the drive motor unit 43 side in the housing 41, and a urea water chamber (urea formed in the housing 41 from the pressure feed unit discharge port). Urea water is discharged into the water passage. The urea water flows through a gap (urea water passage) between the stator 51 and the magnet rotor 55.

  The housing cover 66 located at the upper end of the urea water pump 22 is provided with a discharge port 22b for discharging urea water to the outside of the pump, that is, the urea water pipe 23, and forms a discharge port 22b as shown in FIG. The discharge section 65 is arranged so as to extend toward the lower side in FIG.

  The drive motor unit 43 is composed of, for example, a three-phase full-wave drive type brushless motor, and is configured as follows. A cylindrical stator 51 is fitted and fixed in the housing 41, and a plurality of salient poles 52 are formed on the stator 51. The salient pole 52 is provided with a three-phase armature coil 53. A magnet rotor 55 is disposed on the inner peripheral side of the stator 51. The magnet rotor 55 includes a rotor core 57 fitted to the rotary shaft 56 and a plurality (for example, eight) field magnets 58 fixed to the outer periphery of the rotor core 57 by adhesion or the like. The eight field magnets 58 are arranged so that N poles and S poles are alternately arranged, and thereby an eight pole magnet rotor 55 is configured. Both ends of the rotating shaft 56 of the magnet rotor 55 are rotatably supported by bearings 61 and 62.

  In addition, a drive control circuit 63 of a three-phase full wave drive system is assembled in the housing 41, and when the motor is driven, the drive control circuit 63 sequentially switches the energization of the armature coils 53 of each phase by the three-phase energization system. It is done. The housing cover 66 is fitted into the opening of the housing 41 on the drive control circuit 63 side. The drive control circuit 63 may be provided outside the urea water pump without being integrated with the urea water pump.

  Here, the urea water pump 22 has a configuration in which the rotation direction of the drive motor unit 43 is reversed reversely by changing the excitation order of the three-phase armature coils 53. In addition to discharging to the supply pipe 23 side, it is also possible to suck urea water from the urea water supply pipe 23 side. That is, urea water is discharged from the urea water tank 21 when the urea water pump 22 is driven forward, and urea water is sucked back into the urea water tank 21 when the urea water pump 22 is driven reversely. It is like that.

  As shown in FIG. 1, the pump position adjusting member 29 holds the urea water pump 22 accommodated in the urea water tank 21 directly or indirectly, and the relative position of the urea water pump 22 with respect to the urea water tank 21. Is an actuator that moves the liquid surface in the direction of the liquid surface where the liquid surface of the urea water is displaced.

  Specifically, the pump position adjusting member 29 is a well-known direct acting cylinder that moves the moved member back and forth in the axial direction, and moves the holding portion 29a holding the urea water pump 22 and the holding portion 29a in the liquid surface direction. The holding portion 29a and the shaft portion 29b are supported by a main body of a linear cylinder disposed outside the urea water tank. In addition, by adopting a configuration in which the main body and the urea water tank 21 are fixed, the pump position adjusting member 29 can easily move the relative position of the urea water pump 22 with respect to the urea water tank 21.

  The pump position adjusting member 29 is not limited to a linear cylinder that moves the urea water pump 22 that is a moved member back and forth in the axial direction, but a shaft portion that can be screwed directly or indirectly to the moved member; An electric actuator or the like having a rotation drive unit that rotates the shaft portion may be used.

  Specifically, the pump position adjusting member 29 is a well-known direct acting cylinder that moves the moved member back and forth in the axial direction, and moves the holding portion 29a holding the urea water pump 22 and the holding portion 29a in the liquid surface direction. The holding portion 29a and the shaft portion 29b are supported by a main body of a linear cylinder disposed outside the urea water tank.

  The pump position adjusting member 29 is not limited to a linear cylinder that moves the urea water pump 22 that is a moved member back and forth in the axial direction, but a shaft portion that can be screwed directly or indirectly to the moved member; An actuator or the like having a rotation drive unit that rotates the shaft portion may be used.

  Here, the urea water used as the reducing agent is frozen at −11 ° C., and the volume increases by about 7% by solidifying from the liquid state accompanying the freezing. In this case, after the engine is stopped, urea water remains in each component of the urea water supply system (such as the urea water addition valve 15 and the urea water supply pipe 23), and when the volume of the residual urea water increases due to freezing, The urea water addition valve 15 and the urea water supply pipe 23 may be damaged.

Therefore, in this embodiment, as a measure for preventing damage to each component of the urea water supply system due to freezing of urea water,
(1) After the engine is stopped, the urea water pump 22 is driven in a urea water sucking back state (reverse rotation driving state) different from the normal urea water pumping state (forward rotation driving state), thereby downstream of the urea water pump 22 A “suck back process” is performed to return (return) the urea water remaining in the urea water addition valve 15 and the urea water supply pipe 23 arranged on the side to the urea water tank 21 side.

  (2) In order to make it easy to form the urea water sucking back state, a non-volumetric pump (turbine pump) pumping mechanism is employed in the pumping section 42 of the urea water pump 22 in this embodiment.

Since the pumping unit 42 is the pumping mechanism, the pump chamber 46 of the pumping mechanism is always in communication with both the suction port 22 and the pumping unit discharge port. Therefore, if the urea water pump 22 remains immersed in the urea water liquid, at least the urea in the pump chamber 46 even after the “suck back process” of (1) above is performed. There is a possibility that the water will remain and the urea water pump 22 itself may be damaged by the pressure feeding mechanism of the pressure feeding section 42 due to the freezing of the remaining urea water. Therefore,
(3) In the present embodiment, when the “suck back process” is performed after the engine is stopped, urea water is contained in the urea water pump 22 in order to prevent damage to the urea water supply system due to urea water freezing. In order not to remain, “pump position adjustment processing” is performed in which the urea water pump 22 is separated from the surface of the urea water.

  (4) Specifically, the pump position adjusting member 29 switches the first state and the second state by moving the relative position of the urea water pump 22. As a method of realizing the second state of the urea water pump 22, the ECU 30 drives the pump position adjusting member 29 based on the liquid level detected by the liquid level sensor (hereinafter referred to as urea water detection liquid level). Thus, the bottom of the urea water pump 22 is separated to a level equal to or higher than the urea water detection liquid level. However, the present invention is not limited to this, and the urea water pump 22 is moved to an upper limit position that is equal to or higher than a liquid level at which the urea water is fully filled (hereinafter, full liquid level) when the urea water tank 21 is supplied. May be.

  The operation of the urea water supply apparatus 20 having the above-described configuration will be described with reference to FIGS. 2 to 4 showing the processing of each pneumatic means executed by the ECU 30. FIG.

  As shown in FIG. 2, in S10 (S is a step), the ECU 30 detects the engine state by reading various engine states, and in S20, reads the engine state, and in S20, after the engine is stopped based on the read engine state. It is determined whether or not there is. An indispensable condition for determining after the engine has stopped in the engine state is, for example, that the engine speed is 0 or the ignition switch is OFF, and whether or not this indispensable condition is satisfied. It is done by judging.

  If it is determined in S20 that the engine has been stopped, the process proceeds to S30, and a suck back process (see FIG. 4) is performed. Conversely, if it is determined that the engine has not been stopped, the process proceeds to S40 to purify the exhaust gas flowing out of the engine when the engine is in operation, and the urea water pump 22 and the like are controlled in the normal urea water pressure feed state. Perform processing. And when either of the control processing of S30 and S40 is complete | finished, it transfers to S50 and implements a pump position adjustment process (refer FIG. 3).

  Next, the suck back control of the urea supply system will be described with reference to FIG. In the control process of S31 and S32, it is determined whether or not the urea water suction has been completed after the engine is stopped. The suck back determination is performed by determining whether or not the suck back completion flag is 1 (suck back completion = 1). Then, the process proceeds to S33 on the condition that after the engine is stopped and the urea water suction is not completed.

  In S33, it is determined whether or not a predetermined time has elapsed after the urea water sucking back (reverse rotation driving of the urea water pump 22) is started. If it is before the predetermined elapsed time, S34 and S35 are executed. That is, the urea water pump 22 is driven to rotate in reverse (driven in the urea water sucking back state), and in S35, the urea water addition valve 15 is energized. At this time, it is preferable to start energization of the urea water addition valve 15 with a delay of several seconds from the start of the reverse rotation driving of the urea water pump 22.

  Further, when a predetermined elapsed time has elapsed after the urea water sucking back is started, S36 and S37 are executed. That is, in S36, the driving of the urea water pump 22 is stopped, and in S37, the energization of the urea water addition valve 15 is ended. Thereafter, in S38, 1 is set to the suck back completion flag.

  Here, FIG. 5 shows a mode of the suck back process. As shown in FIG. 5, after the engine is stopped, the urea water pump 22 is driven in reverse rotation, and the urea water addition valve 15 is energized to open the addition port of the urea water addition valve 15. At this time, in order to avoid leakage of urea water into the exhaust pipe 11, the urea water pump 22 is first driven in the reverse rotation driving state, and then the urea water addition valve 15 is energized. preferable. However, the reverse rotation drive of the urea water pump 22 and the energization of the urea water addition valve 15 can be performed simultaneously.

Next, the position adjustment control of the urea water pump 22 will be described with reference to FIG.
In the control processing of S51 and S52, it is determined whether or not the urea water suction has been completed after the engine is stopped.

  If it is determined in S51 that the essential condition for determination after engine stop is not satisfied, that is, it is determined that the engine is operating, S53, S57, and S59 are executed. That is, in S53, the urea water detection liquid level Hu detected by the liquid level sensor is read. In S57, whether the urea water detection liquid level Hu is equal to or higher than the suction port 22a of the urea water pump 22 (Hu ≧ Hup). That is, it is determined whether or not the position of the urea water pump 22 with respect to the urea water detection liquid level Hu is so immersed that the suction part 48 in which the suction port 22a is formed is immersed. If it is determined in S57 that the suction part 48 is not so immersed in the urea water detection liquid level Hu, the process proceeds to S59. In S59, it is determined that the urea water pump 22 is not sufficiently immersed in the urea water solution, and the urea water pump 22 is moved as far downward as possible in the liquid level.

  Thereby, the urea water is not interrupted in the middle of the urea water supply system during the process of controlling the urea water pump 22 and the like in a normal urea water pressure feeding state.

  If it is determined in S51 and S52 that the engine has been stopped and the urea water suck-back has been completed, the process proceeds to S56.

  In S56, the urea water pump 22 is moved upward in the liquid surface direction, and the bottom of the urea water pump 22, that is, the suction port 22a is pulled away from the liquid surface of the urea water.

  In the present embodiment described above, the urea water pump 22 is driven in a urea water sucking back state different from the urea water pumping state after the engine is stopped, so the urea water addition valve 15 disposed on the downstream side of the urea water pump 22. In addition, the urea water remaining in the urea water supply pipe 23 can be returned to the urea water tank 21 and collected. As a result, the urea water is prevented from freezing in the urea water addition valve 15 and the urea water supply pipe 23, and as a result, breakage of these members can be suppressed.

  In the present embodiment, even if the urea water sucking back is completed, if the urea water pump 22 is left immersed in the urea water solution, the urea water remains in the urea water pump 22. In view of this, the urea water pump 22 is separated from the surface of the urea water by the pump position adjusting member 29. As a result, all the remaining urea water can be recovered from the suction port 22 a of the urea water pump 22 to the urea water tank 21 without the urea water remaining in the urea water pump 22.

  Therefore, the urea water is prevented from freezing in the urea water addition valve 15, the urea water supply pipe 23, and the urea water pump 22 constituting the urea supply system, so that damage to these members can be suppressed. That is, in all the members of the urea supply system, it is possible to prevent freezing of urea water and damage due to freezing of urea water, so that each member of the urea supply system can be reliably protected.

  In this embodiment, a non-positive displacement pump (turbine pump) type pressure feeding mechanism is used for the pressure feeding portion 42 of the urea water pump 22. In addition, the urea water pump 22 does not have a check valve for suppressing the flow of urea water in the urea water passage between the suction port 22a and the discharge port 22b. In such a urea supply system using the urea water pump 22, the “pump position adjustment process” is performed on the condition that the engine is stopped, and the urea water pump 22 is separated from the liquid surface of the urea water. Also good.

  This is because, in the urea supply system using the urea water pump 22, the urea water passage between the urea water addition valve 15, the urea water supply pipe 23, and the urea water pump 22 is always in communication with the suction port 22a. That is, because of the communication state, the urea water in the urea supply system can be returned to the urea water tank 21 from the suction port 22a even when the “suck back process” is not completed or not performed. is there.

  However, the urea water pump 22 is not forcibly performed by driving the urea water pump 22 in the urea water sucking back state as in the “suck back processing”. Therefore, in the “suck back processing”, the urea water in the urea supply system can be returned to the urea water tank 21 relatively quickly, whereas it can be gradually returned from the suction port 22a to the urea water tank 21. Is possible.

  Here, the “pump position adjustment process” is performed on the condition that the engine has been stopped when the “suck back process” is not performed and the “pump position adjustment process” is performed. Because there is. When the engine is stopped, no exhaust gas is generated from the engine. Therefore, it is not necessary to supply urea water to the SCR catalyst 13, so that the urea water pump 22 is not pumped, that is, for pumping. This is because the urea water below the liquid level is not sucked up from the suction port 22a side of the urea water pump 22.

  Further, in the present embodiment described above, the “pump position adjustment process” is performed on the condition that the engine has been stopped, and the urea water pump 22 is separated from the liquid level of the urea water. For example, the liquid level position is detected. It is possible to move to a set position (upper limit position equal to or higher than the full liquid level in the urea water tank 21) that is always separated from the preset liquid level. Therefore, it is possible to avoid the retention of the urea water in the urea water pump in order to prevent the urea water pump from being damaged by the urea water freezing by a relatively simple method.

  In the present embodiment described above, the means (pump position adjusting member 29) for performing the “pump position adjusting process” is an electric actuator that holds the urea water pump 22 and moves it in the liquid surface direction. . As a result, as an electric actuator, for example, a combination of a screw shaft capable of axially moving a holding portion that holds a urea water pump and a motor that rotates the shaft, or a direct acting motor that directly drives a shaft such as a cylinder shaft Etc. can be used.

(Second Embodiment)
Hereinafter, other embodiments to which the present invention is applied will be described. In the following embodiments, the same or equivalent components as those in the first embodiment are denoted by the same reference numerals, and description thereof will not be repeated.

  A second embodiment is shown in FIG. The second embodiment shows an example of a urea water pump unit (urea water pump module) in which a filter 124 and a regulator 125 are incorporated in the urea water pump 22. FIG. 7 is a partial cross-sectional view showing a urea water supply unit in which the urea water pump according to the present embodiment is unitized (module).

  The urea water pump unit (urea water pump module) is provided in the urea water pump 22, the urea water tank 21, a holding wall member 171 that houses and holds the urea water pump 22 inside, and a pump position adjusting member. 129 and 179 are provided with a connecting portion 173, a filter 124, a gulator 125, and a suction filter 181.

  The filter 124 includes a filter element 124a and a filter case 124b. The filter element 124a removes foreign substances contained in the urea water discharged from the urea water pump 22. The filter case 124b accommodates the filter element 124a therein and is formed in a substantially cylindrical shape. The inlet of the filter case 124b is fitted and coupled to the discharge port 22b side of the urea water pump 22. Further, the outlet of the filter case 124 b is connected to the inlet passage 125 a side of the regulator 125.

  The outflow passage side of the regulator 125 is connected to the urea water discharge pipe 184 of the lid member 182 through the bellows pipe 183 having the discharge passage 183a. Further, the discharge passage 125 b of the regulator 125 returns the urea water surplus when the pressure is regulated by the regulator 125 out of the urea water discharged from the urea water pump 22 into the urea water tank 21.

  The lid member 182 is formed in a substantially disk shape, is engaged with and attached to the opening of the upper wall 21a of the urea water tank 21, and covers the opening of the upper wall 21a. The lid member 182 has a disc portion 182a and an annular wall portion 182b, and the annular wall portion 182b is formed so as to be insertable into the opening of the upper wall 21a.

  In addition to the urea water discharge pipe 184 having the urea water discharge port 184a, the disk portion 182a of the lid member 182 includes an electrical connector 185 and an insertion hole 182c through which the pump position adjusting members 129 and 179 can be inserted. The electrical connector 185 supplies power to the urea water pump 22 through the lead wire 186.

  The pump position adjusting members 129 and 179 include a shaft portion 179 that can be screwed directly or indirectly to the member to be moved, and a rotation drive portion 129 that rotates the shaft portion 179. The rotation drive unit 129 is a known electric motor such as a servo motor or a brushless motor. One end portion of the shaft portion 179 extends toward the bottom wall 21 b of the urea water tank 21, and the other end portion passes through the insertion hole 182 c of the lid member 282 and is connected to the rotation driving unit 129.

  The shaft portion 179 is connected to a connecting portion 172 provided on the outer peripheral side of the holding wall member 171 and is screwed to the connecting portion 172. The shaft portion 179 allows the connecting portion 172, that is, the holding wall member 171 to move in the liquid surface direction (vertical direction in the drawing) by the rotation of the shaft portion 179 by the rotation driving portion 129. Accordingly, the pump position adjusting members 129 and 179 indirectly hold the urea water pump 22 via the holding wall member 171 and can move in the liquid surface direction.

  The holding wall member 171 is formed in a cylindrical shape, and includes a cylinder main body portion 171 h, a connecting portion 172, and a coupling portion 182. The coupling portion 182 is coupled to the tube main body portion 171 h and the filter case 124 b, and supports the urea water pump 22 through the filter 124.

  The suction filter 181 is connected to the suction port 22 a side of the urea water pump 22 and removes foreign matters contained in the urea water sucked up by the urea water pump 22.

  Here, in order to protect the functions of the pump itself and an external device to which the fluid is supplied, a pump that sucks in a stored fluid such as urea water and pumps the fluid to the outside is generally used. A foreign substance removing device (filtering device) is provided on at least one of the sides. Therefore, the pump is configured as an assembly (module) in which members such as a foreign substance removing device (filtration device) are assembled. For example, when the pump is directly held by the pump position adjusting member, an assembly (module) in which a member such as a foreign substance removing device (filtering device) is assembled is formed between the pump position adjusting member and the pump. May be difficult.

  In contrast, in the present embodiment, the urea water pump 22 is accommodated and held inside the cylindrical holding wall member 171, and the pump position adjusting members 129 and 179 are connected to the holding wall member 171 via the connecting portion 172. It has a structure to do. In this way, the pump position adjusting members 129 and 179 do not directly hold the urea water pump 22, but the pump position adjusting members 129 and 179 indirectly hold the urea water pump 22 via the holding wall member 171. In the space formed between the holding wall members 129 and 179 and the urea water pump 22, members constituting the assembly (module) such as the filter 124, the regulator 125, and the suction filter 181 are provided. It can be assembled intensively.

(Third embodiment)
A third embodiment is shown in FIG. The third embodiment shows an example in which the holding wall member is a sub tank 271 capable of storing urea water therein. FIG. 8 is a partial cross-sectional view showing a urea water supply unit according to this embodiment.

  The sub tank 271 is formed in a bottomed cylindrical shape, and contains the urea water pump 22, the filter 124, the regulator 125, the suction filter 181, and the like. The sub tank 271 includes a cylinder main body portion 171h, a connecting portion 172, a coupling portion 182 and a bottom portion 171a. The bottom 171a is provided with a suction port 271b for pumping urea water outside the sub tank, that is, in the urea water tank 21, into the sub tank 271.

  Thus, when the urea water pump 22 sucks urea water in the sub tank 271 and discharges it outside, the urea in the urea water tank 21 is brought into the sub tank 271 through the suction port 271b using the suction input of the urea water pump 22. Water can be pumped up, and urea water can be stored in the sub tank 272 separately from the urea water tank 21. In addition, when the urea water pump 22 is stopped, the suction input of the urea water pump 22 is lost, so the urea water in the sub tank 271 is returned to the urea water tank 21 through the suction port 271b.

  That is, when the engine is stopped, as a method of separating the urea water pump 22 from the liquid surface, it is not necessary to directly separate the suction port 22a side of the urea water pump 22 from the liquid surface of the urea water in the urea water tank 21, and the sub tank An indirect method of pulling the bottom portion 271a of 271 away from the liquid surface can be used.

  For example, by appropriately setting the size of the suction port 271b, it is possible to adjust the time for returning the urea water accumulated in the sub tank 271 to the urea water tank 21 after the urea water pump 22 is stopped. is there. Thereby, for example, even when the engine stop is a temporary stop, when the engine operation is started, the urea water temporarily remaining in the sub tank 271 after the stop of the urea water pump 22 is used to perform the pressure feeding. Therefore, the urea water can be sucked into the urea water pump 22.

  Further, in the present embodiment, as shown in FIG. 8, it is preferable to include a jet pump 222 that is provided in the sub tank 271 and pumps urea water outside the sub tank into the sub tank 271 from the suction port 271b. The jet pump 222 is connected to the discharge passage 125 b side of the regulator 125.

  A jet pump generally constitutes an assembly (module) together with members such as a pump and a foreign substance removing device (filtering device), and a part of fluid discharged from the pump to the outside of the pump (for example, pressure of a regulator or the like) The negative pressure generated by the reflux flow that returns (returns) the fluid surplus when the pressure is adjusted by the regulating valve to the sub-tank is used as the fluid pumping force.

  On the other hand, in the present embodiment, since such a jet pump 222 is provided in the sub tank 27, urea discharged from the excess of the urea water, that is, the urea water pump 22 when the pressure is adjusted by the regulator 125, is discharged from the pump. The urea water outside the sub tank can be efficiently pumped into the sub tank 271 from the suction port 271b using the negative pressure of the jet pump 222 generated when a part of the water is returned to the sub tank 271.

  Therefore, even when the urea water pump 22 is temporarily separated from the urea water level by the pump position adjusting members 129 and 179 when the engine is stopped, after the engine operation is started, for example, the bottom 271b of the sub tank 271 is placed in the urea water. By simply moving the relative position of the urea water pump 22 by the pump position adjusting members 129 and 179 to such an extent that the urea water is immersed in the surface of the urea water in the tank 21, the flow of urea water discharged by driving the urea water pump 22 can be changed. The used jet pump 222 can quickly accumulate urea water in the sub tank 271.

(Fourth embodiment)
A fourth embodiment is shown in FIG. The fourth embodiment shows an example in which the pump position adjusting member is a buoyancy body 329 that gives buoyancy to a moved member. FIG. 9 is a partial cross-sectional view showing a urea water supply unit according to the present embodiment.

  Here, the urea water in the urea water tank 21 is consumed according to the supply to the SCR catalyst 13, whereby the liquid level of the urea water decreases according to the consumption amount, or the urea water into the urea water tank 21. The liquid level increases according to the replenishment amount.

  In contrast, in the present embodiment, the pump position adjusting member includes a buoyant body that gives buoyancy to the moved member. The buoyant body holds the sub tank 271, and the urea water pump 22 as the moved member is replaced with the sub tank Through the 271, the suction port 22 a side of the urea water pump 22 is held in a state of being immersed in the liquid surface.

  As a result, the buoyancy body 329 that gives buoyancy to the urea water pump 22 to such an extent that the suction port 22a side of the urea water pump 22 is immersed in the liquid level is simply mounted on the urea water pump 22. Thus, the pump position adjusting member can be provided.

(Fifth embodiment)
A fifth embodiment is shown in FIG. The fifth embodiment shows an example of moving the urea water pump 22 upward in the liquid surface direction on the condition that the urea water temperature Tu is not more than the solidification temperature Tup of the urea water in the “pump position adjustment process”. It is. FIG. 10 is a flowchart showing the position control of the urea water pump according to the present embodiment.

  In the flowchart of FIG. 10, the control processes of S541, S542, and S543 are added between the determination of the control process of S51 in FIG. 3 and the process of S56.

Here, the urea water is not necessarily frozen when the engine is stopped.
Although it is possible to move the relative position of the pump with the engine stop as the first condition (affirmative determination of the control process in S51), a power source such as an in-vehicle battery is used as a driving force generation source other than the engine when the engine is stopped. Therefore, it is necessary to avoid such wasteful consumption of energy such as electric energy.

  In contrast, the present embodiment includes a temperature sensor 28 as a reducing agent temperature detecting means for detecting the temperature of the urea water. In the “pump position adjustment process”, the first condition is satisfied and the urea water temperature Tu is When the second condition that the temperature is equal to or lower than the solidification temperature Tus to be solidified is satisfied, the urea water pump 22 is controlled to move in a direction away from the liquid surface.

  Specifically, in S541, the urea water temperature Tu detected by the temperature sensor 28 is read. In S542, it is determined whether or not the detected urea water temperature Tu is equal to or lower than the solidification temperature Tus. When it is determined that the urea water temperature Tu is equal to or lower than the solidification temperature Tup, the process proceeds to S56, and the urea water pump 22 is pulled away from the liquid level.

  According to this, in addition to the first condition that the engine is stopped, when the second condition that the urea water temperature Tu is equal to or lower than the solidification temperature Tus is satisfied, the urea water pump 22 is pulled away from the liquid surface. Since it is moved, the driving force for moving the urea water pump 22 in the pump position adjusting member is consumed based on the urea water freezing prediction based on the urea water temperature Tu. Therefore, it is possible to avoid consuming unnecessary driving force.

  If it is determined in S541 that the urea water temperature Tu is not equal to or lower than the solidification temperature Tus, the process proceeds to S543. S543 enables the urea water temperature Tu to be detected at a standby time interval of a predetermined time. That is, in S543, it is determined whether or not a predetermined time has elapsed. If it is determined that the predetermined time has elapsed, the process proceeds to S541. If it is determined that the predetermined time has not elapsed, the determination process of S543 is repeatedly performed until the predetermined time has elapsed.

  As a result, the urea water temperature Tu is continuously detected at predetermined intervals during the engine stop period, that is, after the first condition is satisfied. Thus, the driving force by the pump position adjusting member can be generated, and the urea water pump 22 can be separated from the liquid surface in order to prevent pump damage due to urea water freezing.

(Other embodiments)
(1) In the present embodiment described above, as a condition for executing the control for separating the urea water pump 22 from the liquid surface by the “pump position adjustment process”, the urea water sucking back is completed after the engine is stopped (first condition). (The “sucking back process” was performed) (third condition). Not limited to this, the execution condition may be satisfied only by satisfying the first condition (after engine stop). In other words, after the engine is stopped (first condition), the “suck back process” is performed (completed), and the urea water pump 22 by the “pump position adjustment process” is set to the liquid level regardless of whether or not it is being performed. Execute the control to pull away from.

  (2) In the fifth embodiment described above, in addition to satisfying the first condition and the third condition, satisfying that the urea water temperature Tu is equal to or lower than the solidification temperature Tup (second condition). Therefore, it was assumed that the above execution condition was satisfied. Not limited to this, the above-mentioned execution condition may be satisfied by satisfying the first condition (after the engine is stopped) and the second condition (the urea water temperature Tu is equal to or lower than the solidification temperature Tup). Good.

  (3) In the present embodiment described above, as a method for determining whether or not the first condition (after engine stop) is satisfied, the essential condition for determination after engine stop in the engine state is: (A) The engine rotational speed is 0, or (B) the ignition switch is OFF, and the above determination is made by determining whether or not this essential condition is satisfied. It was.

  The present invention is not limited to this, and the following method may be used.

  That is, in the “pump position adjustment process”, when the process executed by the ECU 30 is represented by a function, a stop prediction unit that detects an event that occurs before or after the engine stops and predicts the engine stop based on the detected event And stop condition determining means for determining that the first condition is satisfied when the stop is predicted by the stop predicting means.

  Here, when the engine is used for a vehicle such as an automobile, the engine stop means that the vehicle is parked, such as when an occupant leaves the vehicle, or when idling is stopped to wait for a signal before the intersection, When stopping automatically, the engine is stopped.

  In the method of directly detecting the engine stop as in the method (A) or (B), there is a possibility that even when the engine is temporarily stopped, it is treated as a parking where the stopped state continues. In the case of such a temporary stop, moving the urea water pump 22 away from the liquid surface by the pump position adjusting member means that the pump is being pumped after releasing the temporary stop (after starting the engine). There is a possibility that supply of the urea water pump 22 to the SCR catalyst 13 is interrupted. Therefore, it is necessary to detect a driver operation event related to the driver's operation on the vehicle-related device and to detect a stop of the engine related to parking.

  On the other hand, in the “pump position adjustment process” having the stop prediction unit and the stop condition determination unit, for example, as a phenomenon that occurs before or after the engine is stopped, the driver prepares for parking by stepping on a parking brake such as a vehicle side brake. The state (parking brake ON state) can be detected. By detecting such a parking preparation state and predicting continuous stoppage, that is, parking by the stop prediction means, the engine stop condition determined by the stop condition determination means efficiently detects engine stop related to parking. be able to.

  (4) In the present embodiment described above, the urea motor pump 22 uses a brushless motor as the drive motor for the drive motor unit 43, and the pressure feed unit 42, which is a Durbin-type pump-type pressure feed mechanism. By changing the excitation order of the three-phase armature coils 53, the rotation direction of the drive motor unit 43 is reversed in the forward and reverse directions. Not limited to this, the rotation direction of the drive motor unit is a drive motor that can rotate in the first direction in which the pressure feeding mechanism pumps urea water out of the pump and in the second direction in which the pressure feeding mechanism sucks urea water from outside the pump. Any motor structure may be used.

  In the urea water pump having such a drive motor unit, the rotation direction is set to the first direction so that the urea water pump is pumped to the upstream side of the SCR catalyst 13 through the urea water passage such as the urea water supply pipe 23. In addition, the urea water in the urea water supply pipe 23 can be sucked back to the urea water pump side by reversing the rotation direction and setting the second direction.

  That is, the urea water in the urea water supply pipe 23 can be recovered in the urea water tank 21 through the urea water pump by driving the urea water pump in a reducing agent sucking back state different from the reducing agent pumping state.

  Moreover, since the urea water pump is directly or indirectly held by the pump position adjusting member and is movable, the urea water in the urea water supply pipe 23 is collected in the urea water tank 21 through the urea water pump. The urea water remaining in the urea water pump can also be discharged into the urea water tank 21. That is, a urea water pump such as a urea water supply pipe by freezing urea water is provided by including a device including a urea water pump having the drive motor unit and performing the “suck back processing” and “pump position adjustment processing”. The passage and the urea water pump can be reliably prevented from being damaged.

  (5) In the present embodiment described above, urea water (urea aqueous solution) is used as the reducing agent added to the SCR catalyst 13. The present invention is not limited to this, and the present invention can be applied to an exhaust purification catalyst that is supplied with a liquid reducing agent. In order to prevent damage to the reducing agent pump due to freezing of the liquid reducing agent, it is possible to prevent the reducing agent from remaining in the reducing agent pump in the reducing agent supply system.

It is a schematic diagram which shows the whole apparatus of the urea water SCR apparatus to which the urea water supply apparatus of the 1st Embodiment of this invention is applied. It is a flowchart which shows the control which returns the urea water collected in the urea water supply system to the drainage tank with urea water supply in a urea water supply apparatus. It is a flowchart which shows the position control of the urea water pump corresponding to the subroutine process performed by step 50 in FIG. FIG. 3 is a flowchart showing urea water suck-back control corresponding to a subroutine process executed in step 30 in FIG. 2. FIG. It is a schematic diagram which shows the sucking-back mode for urea water collection | recovery. It is sectional drawing which shows an example of the internal structure of a urea water pump. It is a fragmentary sectional view which shows the urea water supply part which united the urea water pump concerning 2nd Embodiment into the unit (module). It is a fragmentary sectional view which shows the urea water supply part concerning 3rd Embodiment. It is a fragmentary sectional view which shows the urea water supply part concerning 4th Embodiment. It is a flowchart which shows the position control of the urea water pump concerning 5th Embodiment.

Explanation of symbols

11 Exhaust pipe 12 DPF
13 SCR catalyst (exhaust purification catalyst)
15 Urea water addition valve (reducing agent addition valve)
21 Urea water tank (reducing agent tank)
22 Urea water pump 22a Suction port 22b Discharge port 23 Urea water supply pipe (reducing agent supply pipe, reducing agent passage)
24 Filter (filtering device, foreign matter removing device)
25 Regulator (Pressure adjustment valve)
28 Temperature sensor (reducing agent temperature detection means)
29 Pump position adjusting member (pump position adjusting means)
29a Holding part 29b Extendable part 30 ECU (control part)
42 Pumping section (pumping mechanism)
43 Motor part (drive motor)
44 Pump casing 45 Pump cover 46 Pump chamber 47 Impeller 48 Suction part 51 Stator 52 Salient pole 53 Armature coil 55 Magnet rotor 56 Rotating shaft 57 Rotor core 58 Magnet 61, 62 Bearing 63 Drive control circuit 65 Discharge part 66 Housing cover

Claims (13)

A reducing agent tank that stores a liquid reducing agent; and a pump that is housed in the reducing agent tank and that pumps the reducing agent in the reducing agent tank out of the reducing agent tank,
In a reducing agent supply device that supplies a reducing agent that is pumped through the reducing agent passage from the pump to the upstream side of the exhaust purification catalyst that is an exhaust passage of the internal combustion engine,
A reducing agent supply apparatus comprising pump position adjusting means for moving the relative position of the pump with respect to the reducing agent tank in a liquid surface direction in which the liquid surface of the reducing agent is displaced. Comprising stop detection means for detecting a stop of the internal combustion engine,
2. The reducing agent supply device according to claim 1, wherein the pump position adjusting unit moves the pump in a direction away from the liquid level on condition that the internal combustion engine is detected by the stop detection unit. .   3. The reducing agent supply apparatus according to claim 1, wherein the pump position adjusting unit is an electric actuator that holds the pump and moves the pump in the liquid surface direction. 4. The pump position adjusting means includes a buoyancy body that gives buoyancy to the moved member,
The said buoyancy body is holding the said pump as the said to-be-moved member in the state in which the inlet port which suck | inhales a reducing agent in the said pump is immersed in the said liquid level. Reducing agent supply device. The stop detection means includes
Stop prediction means for detecting an event that occurs before or after stopping the internal combustion engine and predicting the stop of the internal combustion engine based on the detected event;
When a stop is predicted by the stop prediction unit, a stop condition determination unit that determines that the condition is satisfied;
The reducing agent supply device according to claim 2, comprising: A reducing agent temperature detecting means for detecting the temperature of the reducing agent;
The pump position adjusting means satisfies the first condition as the condition and satisfies the second condition that the second condition is that the temperature of the reducing agent is equal to or lower than a solidifying temperature. 6. The reducing agent supply device according to claim 2, wherein the reducing agent supply device is moved in a direction away from the liquid surface.   The reducing agent supply device according to claim 6, wherein the reducing agent temperature detecting unit detects the temperature of the reducing agent at a predetermined waiting time interval after the first condition is satisfied. The pump is
A pumping mechanism for sucking the reducing agent from the outside, and a pumping mechanism for pumping the reducing agent flowing in through the suction unit;
A driving motor for driving the pressure feeding mechanism, wherein the rotation direction of the driving motor is determined in a first direction in which the pressure feeding mechanism pumps the reducing agent to the outside of the pump, and the pressure feeding mechanism sucks the reducing agent from the outside of the pump. A drive motor rotatable in a second direction;
The reducing agent supply apparatus according to any one of claims 1 to 7, further comprising: The pump;
A holding wall member which is provided in the reducing agent tank, accommodates and holds the pump inside, and
A connecting portion for connecting the pump position adjusting means according to any one of claims 1 to 8 to the holding wall member,
A reducing agent supply apparatus comprising: The holding wall member is a sub tank capable of storing the reducing agent therein,
The reducing agent supply apparatus according to claim 9, wherein the sub tank includes a suction port at a bottom portion for pumping the reducing agent outside the sub tank into the sub tank.   The reducing agent supply apparatus according to claim 10, further comprising a jet pump provided in the sub tank and pumping the reducing agent outside the sub tank into the sub tank from the suction port. After the internal combustion engine is stopped, the pump includes suck back control means for driving the pump in a reducing agent sucking back state different from the reducing agent pumping state,
The pump position adjusting means moves the pump in a direction away from the liquid level on the third condition that the suck back control means is implemented. Item 7. The reducing agent supply device according to any one of Items 6 to 6. The reducing agent is an aqueous urea solution, and the exhaust purification catalyst promotes an exhaust purification reaction for reducing NOx contained in the exhaust gas by ammonia generated from the aqueous urea solution.
The reducing agent supply device according to any one of Claims 1 to 12, wherein the pump is configured to promote the specific exhaust purification reaction based on the addition of the reducing agent in the exhaust purification catalyst. A reducing agent supply apparatus, wherein the reducing agent fed under pressure is added and supplied into the exhaust passage.

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