JP2008157218A - Reducing agent pressure pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an urea water pressure pump capable of preventing urea water from being frozen in a delivery pipe used for delivering the urea water to an area where the urea water is mixed with exhaust gas when the urea water is pumped through the pressure pump at a low temperature. <P>SOLUTION: The urea water pressure pump is activated to raise the pressure of urea water in a pump passage 23 of a pressurizing unit 18, to thereby pump the urea water to a circulation passage 38 of a drive unit 19. The circulation of the urea water through the pressurizing unit 18 and the drive unit 19 converts a part of energization energy caused by the energization of a coil 29 for magnetizing a stator core 25 into thermal energy, thus causing a rise in a temperature of the stator core 25. Thus, the urea water passing through the circulation passage 38 and having a raised temperature is pumped to an injection valve 6 at desired pressure without being frozen. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a reducing agent pressure feed pump that pumps and feeds a liquid reducing agent such as urea water or alcohol fuel into the inside thereof, and more particularly, urea water pressure constituting a part of a urea SCR system in an exhaust purification device of an internal combustion engine. The present invention relates to a feed pump and a reducing agent pressure feed pump that constitutes a part of a NOx occlusion reduction catalyst (NSR catalyst) system in an exhaust purification device of an internal combustion engine.

  In recent years, the urea SCR system has been developed as an exhaust purification device that is applied to power plants, various factories, and automobiles (especially automobiles equipped with diesel engines) to purify NOx (nitrogen oxides) in exhaust gas with a high purification rate. Has been promoted, and some have been put to practical use. As this urea SCR system, for example, Patent Document 1 discloses the configuration of the apparatus (system).

  Note that SCR is an abbreviation for Selective Catalytic Reduction, and is called a selective catalytic reduction denitration apparatus. In the urea SCR system, urea water is blown against NO or NO2 contained in exhaust gas and reacted with an SCR catalyst, whereby NOx is decomposed and released into N2 and H2O to purify exhaust gas.

  The urea SCR system disclosed in Patent Document 1 is supplied with a urea tank 1 that stores urea water, a pump unit 4 that pumps urea water, and a mixed gas of urea water and exhaust gas pumped from the pump unit 4. The catalyst device 30 for purifying the exhaust gas, and the flow paths 1a, 12, 25 and the like for circulating urea water by connecting the flow paths between these components.

  The pump unit 4 is a pumping unit that pumps urea water, and is provided separately from a motor 4a as a driving unit that drives the pumping unit. The pump unit 4 and the motor 4a are combined to constitute a urea water pressure feed pump.

In the urea water pressure pump having this configuration, the urea water from the urea tank 1 is configured to circulate toward the catalyst device 30 only through the pump unit 4 without passing through the motor 4a as the drive unit.
JP-T-2004-509276

  The urea water which distribute | circulates a urea SCR system is a liquid mixture of a urea component and a water component. For this reason, the water component freezes at a low temperature. The system configuration disclosed in Patent Document 1 in which a urea SCR system in an exhaust gas purification apparatus for an internal combustion engine is shown has a problem with respect to the freezing of urea water described below.

  When a low temperature startable liquid urea water is stored in the urea tank 1 at a low temperature start of the internal combustion engine, a delivery pipe path (flow path) for delivering the urea water to a position where it is mixed with exhaust gas 1a, 12, 25, etc.) is assumed to be below the freezing temperature of the urea water.

  Under this circumstance, when the urea water pressure pumps 4 and 4a are driven to pump, the urea water sent from the pump unit 4 is in the middle of a delivery pipe route for delivering the urea water to a position where the urea water is mixed with the exhaust gas. There is a risk of urea water freezing. If the urea water freezes, it is a problem because the urea water cannot be supplied to the catalyst device 30.

  Furthermore, urea water is a fluid having corrosiveness and alkalinity. For this reason, when urea water is circulated inside the urea water pressure pump, the portion in contact with the urea water is corroded and oxidized, which impairs the function of the pressure pump. The above-mentioned problems relating to freezing and corrosion can also occur with reducing agents other than urea water.

  It is an object of the present invention to freeze a reducing agent in the middle of a delivery pipe that delivers the reducing agent to a position where the reducing agent is mixed with exhaust gas when a reducing agent such as urea water flows into the interior at a low temperature and is pumped. It is in providing the reducing agent pressurization pump which suppresses this.

  Another object of the present invention is to provide a reducing agent pump that can maintain the function as a pump without corroding or oxidizing the portion in contact with the reducing agent when the reducing agent such as urea water flows into the inside and pumps it. Is to provide.

  In the invention of claim 1, a pumping unit having a mechanism unit for pumping a liquid reducing agent such as urea water, a driving unit for generating a driving force for driving the mechanism unit to pump the reducing agent, and a pumping unit And a flow path through which the reducing agent pumped out is circulated via the drive unit, and the portion of the flow path that is exposed to the reducing agent has a corrosion-resistant structure having corrosion resistance and oxidation resistance to the reducing agent. It is formed of a material.

  According to the above configuration, the portion of the flow path that is exposed to the reducing agent is composed of the corrosion-resistant constituent material, so that the reducing agent (urea component of urea water, etc.) is not mainly corroded and oxidized, The function of each part and the heat transfer to the reducing agent can be stabilized.

  In the inventions of claim 2 and claim 25, the corrosion-resistant component is exposed to the reducing agent at the surface portion exposed to the reducing agent to form a passive film, and the metal oxide contained in the inner layer thereof It is formed of a passive film regenerating material that combines with a reducing agent to regenerate the passive film.

  According to the above configuration, since the passive film regeneration material is adopted as the corrosion-resistant constituent material, the reducing agent as a fluid having oxidizing power can be obtained even if the passive film on the surface portion exposed to the reducing agent is lost. Thus, the passive film can be regenerated, and the corrosion resistance and oxidation resistance of each part of the pumping unit and the driving unit can be stabilized.

  In the invention of claim 3, the pressure feeding part is disposed in the pump chamber with a relative position between the pump case in which the reducing agent flows and a pump case forming the inside of the pump chamber and the inner space of the pump chamber being defined. And a rotary pumping body that pumps the reducing agent by a rotating operation, and the pump case is made of a passive film regenerating material.

  According to the above configuration, the pump case is formed of the passive film regenerated material, thereby stabilizing the inner space of the pump chamber exposed to the reducing agent, and the relative position between the inner space of the pump chamber and the rotary pumping body is set. It can be stabilized.

  In the invention of claim 4, the pump case is a pump chamber in which two members of the upper case and the lower case are joined, and the section screen that divides the chamber faces the inside of the mating surface to be joined. The upper case and the lower case are both formed of a passive film reclaimed material of the same material.

  According to the above configuration, since both the upper case and the lower case are formed of the same passive film reclaimed material, the same linear expansion coefficient is set as the pump case. This stabilizes the dimensions of the pump chamber formed by the mating surfaces of the upper case and the lower case in a cold environment, and can stabilize the pump performance.

  The invention according to claim 5 is characterized in that both the upper case and the lower case are made of austenitic stainless steel as a passive film regenerated material.

  According to the above configuration, the austenitic stainless steel has excellent mechanical properties such as high hardness by cold working while being excellent in intergranular corrosion resistance. Therefore, it is possible to easily form an upper case and a lower case that require high-precision processing, and to exhibit excellent corrosion resistance and oxidation resistance against a reducing agent.

  According to a sixth aspect of the present invention, the pumping unit is configured such that a relative position between a pump case that forms a pump chamber into which the reducing agent flows and a space in the pump chamber is fixed to the rotary shaft. A rotationally-pumped body that is disposed indoors and that pumps the reducing agent by its rotational operation; and a pin portion that is pressed against one end of the rotational shaft to define the axial position of the rotational shaft, Is characterized by being formed of a passive film reclaimed material.

  According to the above configuration, the pin portion formed of the passive film regenerated material is in a state where one end of the rotating shaft is pressed against the reducing agent while being exposed to the reducing agent. Stabilizes the surface that is pressed against. From this, the rotary pumping body fixed to the rotating shaft can stabilize the relative position with the space in the pump chamber.

  The invention of claim 7 is characterized in that the pin portion is made of martensitic stainless steel as a passive film regenerating material.

  According to the above configuration, martensitic stainless steel has excellent mechanical properties such as high strength and high hardness by heat treatment (quenching / tempering). From this, it is possible to form a pin portion that exhibits wear resistance when pressed against the rotating shaft and excellent corrosion resistance and oxidation resistance against the reducing agent.

  In the invention of claim 8, the pumping section includes a rotary pumping body that pumps the reducing agent by its rotating operation, and the drive section is electromagnetically driven with respect to the rotor connected by the rotary pumping body and the rotating shaft. A stator core that is exposed to a reducing agent while rotating is provided, and the stator core is formed of a passive film reclaimed material.

  According to the above configuration, the stator core formed of the passive film regenerated material is rotated by being driven electromagnetically, while being exposed to the reducing agent, the surface form of the stator core facing the rotor is stabilized and rotated. The power can be stabilized.

  According to a ninth aspect of the present invention, the stator core is formed of electromagnetic stainless steel having excellent electromagnetic properties as a passive film regenerating material.

  According to the above configuration, the stator core formed of electromagnetic stainless steel has excellent electromagnetic properties and can exhibit excellent corrosion resistance and oxidation resistance against the reducing agent.

  According to a tenth aspect of the present invention, a housing is provided which constitutes a part of the outer shell and in which the outer shell is immersed in a reducing agent, and the housing is formed of a passive film reclaimed material.

  According to the above configuration, the housing formed of the passive film regenerated material is in an environment where the outer portion is immersed in the reducing agent, and can exhibit excellent corrosion resistance and oxidation resistance. .

  The invention according to claim 11 is characterized in that the housing is formed of austenitic stainless steel as a passive film regenerating material.

  According to the above configuration, the austenitic stainless steel has excellent mechanical properties such as high hardness by cold working while being excellent in intergranular corrosion resistance. For this reason, in a housing processed in a thin plate shape and with a high curvature, the housing can be easily formed, and excellent corrosion resistance and oxidation resistance against a reducing agent can be exhibited.

  The invention according to claim 12 is characterized in that the passive film regenerated material is stainless steel.

  According to the above configuration, by using stainless steel as the passive film regenerating material, the passive film can be stably formed in contact with the reducing agent in an environment where the reducing agent is pumped to pump the reducing agent. .

  In a thirteenth aspect of the present invention, a rotary shaft disposed as a shaft body at a rotational center position of a rotary pumping body that pumps the reducing agent by its rotating operation, and a bearing that is exposed to the reducing agent while supporting the rotary shaft. And the bearing portion is formed of a corrosion-resistant constituent material.

  According to the said structure, the bearing part formed with a corrosion-resistant structural material exists in the condition exposed to a reducing agent, supporting a rotating shaft, and can stabilize the performance to support.

  In the invention of claim 14, the corrosion-resistant component constituting the bearing portion is a carbon material that stabilizes slidability at the surface portion exposed to the reducing agent without being exposed to the reducing agent and melted away from the surface portion. It is formed by these.

  According to the said structure, the corrosion-resistant structural material formed with a carbon material can be rotated stably, without being exposed to a reducing agent and melt | dissolving from the surface part.

  In the invention of claim 15, the corrosion-resistant constituent material is a member in which a resin coating layer or a surface treatment layer having corrosion resistance and oxidation resistance to the reducing agent is formed on a surface portion exposed to the reducing agent. It is characterized by.

  According to the above configuration, since the resin film layer or the surface treatment layer is formed on the surface of the member exposed to the reducing agent, the resin film layer or the surface treatment layer has an excellent effect on corrosion resistance and oxidation resistance. Obtainable.

  In a sixteenth aspect of the present invention, the pumping section includes a rotary pumping body that pumps the reducing agent by its rotating operation, and the driving section electromagnetically drives a rotor connected to the rotary pumping body by a rotating shaft. And a resin film layer or a surface treatment layer is formed on the surface layer portion of the stator core.

  According to the said structure, it can suppress that the magnetic steel plate etc. which comprise the stator core are directly exposed to a reducing agent by forming a resin film layer or a surface treatment layer in the surface layer part of a stator core. Therefore, the corrosion resistance and oxidation resistance of the stator core can be improved.

  The invention according to claim 17 is characterized in that the magnetic steel plate constituting the stator core is resin-molded. That is, a resin film layer is formed on the surface layer portion of the stator core by resin molding of the magnetic steel plate. Thereby, it becomes possible to isolate a magnetic steel plate from a reducing agent reliably. In this case, it is preferable that the magnetic steel plates are individually resin-molded and a plurality of them are laminated to form a stator core, or a laminate of a large number of magnetic steel plates is resin-molded to form a stator core.

  In the invention of claim 18, the stator core is housed in the housing member, the stator core is cylindrical, and the flow path is formed on the inner peripheral side thereof. A resin coating layer is formed on the surface layer portion, and a resin cylinder portion is formed integrally with the resin coating layer at the axial end portion, and a contact surface with the housing member is sealed to the outer peripheral portion of the resin cylinder portion. A seal structure is provided.

  In the stator core, a resin coating layer is provided on the inner peripheral side, but a configuration in which the resin coating layer is not provided on the outer peripheral side may be considered. In such a configuration, it is desirable to provide a seal structure on the outer peripheral side of the stator core. According to the eighteenth aspect, the resin cylinder portion is formed integrally with the resin coating layer at the axial end portion of the stator core, and the seal structure is provided on the outer peripheral portion of the resin cylinder portion. It is possible to prevent the reducing agent from entering through the contact surface. Thereby, even if it is the structure which provides a resin film layer locally, corrosion resistance and oxidation resistance can be made favorable in the whole stator core.

  According to a nineteenth aspect of the present invention, the pumping unit includes a rotary pumping body that pumps the reducing agent by its rotating operation, and the driving unit electromagnetically drives a rotor connected to the rotary pumping body by a rotating shaft. The stator core is a reducing agent pressure feed pump having a cylindrical shape and having a flow passage on its inner peripheral side, and the stator core and the flow passage as an anticorrosive component on the inner peripheral side of the stator core. It is characterized in that a cylindrical isolation member for isolating is provided.

  According to the said structure, it can suppress that the magnetic steel plate etc. which comprise the same stator core are directly exposed to a reducing agent by arrange | positioning the cylindrical isolation | separation member which isolates a stator core and a flow path. Accordingly, excellent effects regarding corrosion resistance and oxidation resistance can be obtained.

  The invention according to claim 20 is a reducing agent pump that includes a magnet member that is exposed to the reducing agent in the drive portion and is provided to face the stator core, and a resin coating layer or surface treatment is applied to the surface layer portion of the magnet member. A layer is formed.

  According to the said structure, it can suppress that the said magnet member is directly exposed to a reducing agent by forming the resin film layer or the surface treatment layer in the surface layer part of a magnet member. Therefore, the corrosion resistance and oxidation resistance of the magnet member can be improved.

  The invention according to claim 21 is characterized in that the magnet member is resin-molded. This makes it possible to reliably isolate the magnet member from the reducing agent.

  In a twenty-second aspect of the present invention, a pumping unit having a mechanism unit for pumping a liquid reducing agent such as urea water, and a driving force for driving the mechanism unit to pump the reducing agent are generated. And a flow passage through which the reducing agent pumped and sent out from the pumping unit is circulated through the driving unit to receive the heat generated by the reducing agent.

  According to the above configuration, the reducing agent pressure pump that generates the driving force for driving the driving unit to pump the reducing agent includes the driving unit that generates heat when the driving force is generated. Heat generation due to energization in the drive unit occurs as a part of power conversion loss when the energized energy is converted into power as a pumping force. Even when the reducing agent flows into the inside of the reducing agent pump at a low temperature by causing the reducing agent to receive heat generated by the reducing agent through the flow path, the reducing agent flows into the inside of the reducing agent pump. Can be prevented from freezing inside.

  In the invention of claim 23, the drive unit is provided so as to generate a driving force that is energized to pump the reducing agent, and to generate heat by the energization, and to be in contact with the drive unit and the reducing agent. It is characterized by having a flow passage.

  According to the said structure, the flow path provided so that the drive part and heat | fever which generate | occur | produce at the time of generation | occurrence | production of a driving force and a reducing agent may be provided. Thereby, the reducing agent can receive heat generated by the driving unit by flowing through the flow path.

  According to a twenty-fourth aspect of the present invention, each part of the pumping unit and the driving unit that are exposed to the reducing agent by circulation of the reducing agent is formed of a corrosion-resistant constituent material having corrosion resistance and oxidation resistance against the reducing agent.

  According to the above configuration, each part of the pumping unit and the driving unit made of the corrosion-resistant component is not corroded or oxidized mainly by the reducing agent (urea component of urea water, etc.), , Heat transfer to the reducing agent can be stabilized.

  The invention according to claim 26 is characterized in that the passive film regenerated material is stainless steel.

  According to the above configuration, by using stainless steel as the passive film regenerating material, the passive film can be stably formed in contact with the reducing agent in an environment where the reducing agent is pumped to pump the reducing agent. .

  The invention of claim 27 is characterized in that the reducing agent is urea water. Here, when urea water is used as the reducing agent, good corrosion resistance and oxidation resistance can be exhibited.

  The invention of claim 28 relates to a reducing agent thawing control device for a reducing agent supply system, wherein the detecting means detects the temperature of the reducing agent, and whether or not the reducing agent temperature detected by the detecting means has reached a freezing temperature. Determining means for determining whether the reducing agent temperature has reached the freezing temperature by the determining means, and a pump control means for operating the reducing agent pump in a high output state for reducing agent thawing; It is characterized by providing.

  When the temperature of the reducing agent decreases in a cold region or the like, the reducing agent freezes when the temperature reaches the freezing temperature (−11 ° C. in the case of urea water). In this regard, according to the invention of claim 28, the temperature of the reducing agent is monitored, and when the temperature reaches the freezing temperature, the reducing agent pump is operated in a high output state for reducing agent thawing. The amount of heat generated can be increased and the thawing of the reducing agent can be promoted. Therefore, the frozen reducing agent can be thawed quickly. For example, the reducing agent pressure feed pump is driven with a higher current value than usual to drive the reducing agent pressure feed pump in a high output state for reducing agent thawing.

Hereinafter, based on an embodiment, it explains in detail with reference to drawings about the urea water pressure pump of the present invention.
Embodiment
(Constitution)
The urea water pressure pump according to the embodiment of the present invention is a device that pressurizes and pressure-feeds urea water to an injection valve. The injection valve is arranged to inject urea water into the exhaust flow in the exhaust passage of a diesel engine (hereinafter referred to as an engine) as an internal combustion engine.

  FIG. 1 is an overall configuration diagram showing an overall configuration of a urea SCR system in an embodiment of the present invention. This overall configuration diagram shows an exhaust emission control device for purifying exhaust gas discharged from an engine of an automobile (not shown). The configuration of the exhaust purification device is roughly classified into an exhaust system component, a urea water supply system component, and a control system component.

  The constituent parts of the exhaust system are arranged in order from the exhaust upstream side, DPF1 (Diesel Particulate Filter), exhaust pipe 2 (upstream exhaust passage of the catalyst), catalyst 3, and exhaust pipe 4 (downstream exhaust of the catalyst) Passage).

  The DPF 1 is a continuously regenerating PM removal filter that collects PM (Particulate Matter, particulate matter) in exhaust gas, and repeatedly collects and removes the collected PM by, for example, post injection after main fuel injection ( This is equivalent to the regeneration process of the PM removal filter). Further, the DPF 1 carries a platinum-based oxidation catalyst (not shown) and can remove HC and CO together with a soluble organic component (SOF) which is one of the PM components.

The catalyst 3 is a part that promotes a reduction reaction of NOx and purifies exhaust gas.
4NO + 4NH3 + O2 → 4N2 + 6H2O (Formula 1)
6NO2 + 8NH3 → 7N2 + 12H2O (Formula 2)
NO + NO2 + 2NH3 → 2N2 + 3H2O (Formula 3)
Such a reaction is promoted to reduce NOx in the exhaust. In these reactions, an aqueous solution (hereinafter referred to as urea water) containing ammonia (NH 3) serving as a NOx reducing agent is mixed with exhaust gas and supplied to the catalyst 3. Specifically, urea water is injected and supplied by an injection valve, which will be described later, toward the exhaust gas flowing through the exhaust pipe 2 on the upstream side of the catalyst 3.

  The component part of the urea water supply system includes a urea water supply part 5, an injection valve 6, and a delivery pipe 7. The urea water supply unit 5 includes a urea water tank 8, a urea water pressure pump 9 and the like, and details will be described separately with reference to FIG.

  The injection valve 6 has an injection port formed at its tip so as to atomize and inject the urea water that is pressurized and fed from the urea water tank 8 by the urea water pressure pump 9 and supplied through the delivery pipe 7. Yes. The injection port formed at the tip is constituted by one injection port or an aggregate (group injection hole) of a number of fine injection holes.

  The components of the control system include an ECU 10 (electronic control unit), an exhaust sensor 11, a temperature sensor 12, a pressure sensor 13, and the like. The ECU 10 includes a known microcomputer, and controls drive amounts of various actuators such as the urea water pressure pump 9 and the injection valve 6 based on detection values of the various sensors 11, 12, and 13.

  The exhaust sensor 11 is provided in the exhaust pipe 4 on the downstream side of the catalyst 3, and both the NOx sensor and the exhaust temperature sensor are built in, the amount of NOx in the exhaust (and thus the NOx purification rate by the catalyst 3), and the exhaust It is configured to detect the temperature.

  The temperature sensor 12 is provided on the outer periphery of the urea water tank 8 so that the sensor is not exposed to the urea water, and is configured to detect the temperature of the urea water stored in the urea water tank 8. The pressure sensor 13 is provided in the middle of the delivery pipe 7 and is configured to detect the supply pressure of urea water to the injection valve 6.

  The ECU 10 in the control system described above detects whether or not the temperature of the urea water in the urea water tank 8 is in a state where it can flow without freezing, and detection of the amount of NOx flowing through the exhaust pipe 4. Do. Based on the detected information, the urea water pressure pump 9 is controlled so as to make a drive permission determination and drive an appropriate amount. The injection valve 6 is controlled so that an appropriate amount of urea water is injected and supplied at an appropriate time.

  FIG. 2 is a configuration diagram showing a detailed configuration of the urea water supply unit shown in FIG. The configuration of the urea water supply unit shown in this configuration diagram is roughly classified into a urea water tank 8 and a urea water pressure feeding unit 14.

  The urea water tank 8 is constituted by a sealed container with a liquid supply cap, and urea water having a predetermined concentration is stored therein. In the urea water tank 8, a urea water pressure feed pump 9 disposed as being immersed in the urea water is provided. The urea water pressure pump 9 constitutes an in-tank water pressure pump.

  The urea water pressure feeding unit 14 includes a urea water pressure feeding pump 9, a regulator 15, a filter 16, a strainer 17, and the like. The urea water pressure feed pump 9 is an electric pump that is rotationally driven by a drive signal from the ECU 10, and feeds the urea water in the urea water tank 8 under pressure and supplies it to the injection valve 6. The urea water pressurized and pumped by the urea water pumping pump 9 flows through the delivery pipe 7 and is supplied to the injection valve 6. The detailed configuration of the urea water pressure pump 9 will be described later.

  The regulator 15 regulates the supply pressure supplied to the injection valve 6, and when this supply pressure exceeds a set value, the regulator 15 causes the urea water in the delivery pipe 7 to be fed to the urea water tank 8. Returned.

  The filter 16 filters the urea water. After the foreign matter is removed by the filter 16, the urea water is supplied to the suction port of the urea water pressure pump 9. The filter may be provided in addition to the filter 16 so that the urea water pumped from the discharge port of the urea water pressure pump 9 is filtered and supplied to the injection valve 6.

  The strainer 17 is provided with a suction opening in the vicinity of the bottom of the urea water tank 8, and has a function of an introduction path for filtering large foreign matters and guiding urea water to the filter 16. The urea water pressure feeding unit 14 is provided with a unit case 14a that accommodates the urea water pressure feeding pump 9, the regulator 15, the filter 16 and the like in a compact manner and is immersed in urea water.

  In the urea SCR system having the above-described configuration according to the present embodiment, the urea water in the urea water tank 8 is pumped to the injection valve 6 through the delivery pipe 7 by driving the urea water pressure pump 9 during engine operation. Thus, urea water is added and supplied into the exhaust pipe 2. Then, urea water is supplied to the SCR catalyst 3 together with the exhaust gas in the exhaust pipe 2, and the exhaust gas is purified by performing a NOx reduction reaction in the SCR catalyst 3.

When reducing NOx, for example,
(NH2) 2CO + H2O → 2NH3 + CO2 (Formula 4)
By such a reaction, urea water is hydrolyzed by exhaust heat. As a result, ammonia (NH3) is generated, and this ammonia is added to the NOx in the exhaust gas selectively adsorbed by the SCR catalyst 3. Then, a reduction reaction based on the ammonia (the above reaction formulas (Formula 1) to (Formula 3)) is performed on the catalyst 3, whereby NOx is reduced and purified.

  The urea water used as the reducing agent freezes at −11 ° C., and the urea water cannot be injected and supplied to the exhaust pipe 2 upstream of the catalyst 3 along with the freezing. Therefore, in this embodiment, the urea water freezes in the middle of the delivery pipe that is pumped from the urea water feed pump 9 to the injection valve 6 through the delivery pipe 7 even at a low temperature when the urea water may freeze. With reference to FIG. 3, a urea water pressure feed pump whose configuration is devised so as to suppress this will be described below. FIG. 3 is a configuration diagram showing a detailed configuration of the urea water pressure pump 9 shown in FIG.

  The urea water pumping pump 9 includes a pumping unit 18 having a mechanism unit that pumps urea water, and a driving unit 19 that generates a driving force that drives the mechanism unit to pump urea water.

  The pumping unit 18 is a turbine pump including a pump case and an impeller 22. The pump case joins two members, the upper case 20 and the lower case 21, and forms a space as a pump chamber arranged inside the mating face to be joined so that a section screen that divides the chamber faces. . An impeller 22 as a rotating member whose relative position with respect to this space is defined is rotatably accommodated.

  C-shaped pump passages 23 are formed between the pump cases 20 and 21 and the impeller 22, respectively. The urea water sucked from the suction port 24 provided in the lower case 21 is pressurized in the pump passage 23 by the rotation operation of the impeller 22 and is pumped to the drive unit 19 described later. The mechanism for pumping urea water includes the pump chamber and the impeller 22 described above.

  Each part of the pumping unit 18 and the drive unit 19 through which the urea water is circulated and exposed to the urea water is formed of a urea-resistant component (corrosion-resistant component) having corrosion resistance and oxidation resistance to the urea water. ing. A urea-resistant component (corrosion-resistant component) is exposed to urea water to form a passive film on the surface exposed to urea water, and the metal oxide and urea water contained in the inner layer combine to passivate. It is formed of a passive film regenerating material that regenerates the film.

  Both the upper case 20 and the lower case 21 are austenitic stainless steel as a passive film regenerating material, and are formed using SUS304 classified by JIS classification. The impeller 22 is formed of a phenol resin.

  The drive unit 19 is a brushless motor, and is provided so as to generate a driving force that is energized to pump urea water. Further, when energization for generating the driving force is performed, the energization is provided to generate heat. Heat generation due to energization in the drive unit 19 occurs as part of a power conversion loss when the energized energy is converted into power as a pumping force. The heat energy generated by the heat generation is provided so that the urea water receives heat when the urea water flows through the drive unit. This heat receiving part will be described later.

  The ratio between the amount of energized energy per unit time administered to the drive unit 19 and the passing amount of urea water per unit time flowing through the drive unit 19 is the amount of heat received by the urea water from the desired drive unit 19. As appropriate.

  In the present embodiment, the energization energy amount per unit time administered to the drive unit 19 is set to 20W. The amount of urea water passing through the drive unit 19 per unit time is set in a range of 40 to 60 cc / Min. In the case where the heat dissipation that depends on the ambient environment temperature is not taken into account by the combination setting of the energization energy amount per unit time and the urea water passage amount per unit time, the urea water flowing through the drive unit 19 The temperature rises in the range of 5-7 ° C.

  The setting range of the energization energy amount and the passing amount of the urea water is not limited to the example described in the present embodiment, and the heat receiving from the driving unit 19 to the urea water can be effectively performed by setting the following ranges. Can be done.

  The energization energy amount per unit time administered to the drive unit 19 is set in a range of 10 to 60 W (watts), and the passing amount of urea water per unit time flowing through the drive unit 19 is 40 to 100 cc / Min. It should be set to a range.

  In the present invention, the temperature of the urea water is raised by causing the urea water to receive the heat generated by the drive unit 19 while rotating the rotor 26 described later to distribute the urea water to the drive unit 19, as described above. The temperature of the urea solution is increased by circulating the drive unit 19 only once in the delivery direction.

  The amount of heat received from the drive unit 19 to the urea water can be adjusted not only by one circulation in the delivery direction but also by repeating the delivery operation and the suction operation, and adjusting the number of repetitions. It may be increased.

  The increase in the amount of heat received in the urea water by the drive unit 19 includes, for example, a feed energization operation for obtaining a feed amount for sending the urea solution in the forward direction by rotating the drive unit 19 forward, and a urea feed by reversely driving the drive unit 19. The sucking energization operation for obtaining the sucking amount for sucking water back in the sucking direction is alternately repeated. The amount of heat received by the urea water from the drive unit 19 is increased by the total amount of energization that combines the amount of energization sent by the energization operation and the amount of energization sucked by the suction energization operation.

  Until the desired amount of heat received by the urea water is reached, the delivery amount and the suction amount are set to be the same, and the drive unit 19 is energized so that the delivery amount becomes greater than the suction amount as the temperature of the urea water increases. May be operated. The difference between the delivery amount and the suction amount becomes the actual delivery amount, and urea water with an increased heat receiving amount is delivered.

  The drive unit 19 includes a stator core 25, a rotor 26, a rotation shaft 27, a bobbin 28, and a coil 29.

  The stator core 25 is formed of electromagnetic stainless steel having excellent electromagnetic properties as a passive film regenerating material, and is configured by arranging six cores 30 in the circumferential direction.

  The electromagnetic stainless steel is formed using SUS13A classified as stainless steel.

  The ECU 10 switches the magnetic poles formed on the inner peripheral surface of each core 30 facing the rotor 26 by controlling energization to the coil 29 according to the rotational position of the rotor 26.

  The rotor 26 has a rotating shaft 27 and a permanent magnet 31 and is rotatably installed on the inner periphery of the stator core 25. One end portion of the rotating shaft 27 is rotatably supported by the bearing portion 32, and the other end portion is rotatably supported by the bearing portion 33.

  The urea-resistant constituent material that constitutes the bearing portions 32 and 33 is formed of a carbon material that stabilizes slidability at the surface portion exposed to the urea water without being exposed to the urea water and melted away from the surface portion. Yes. As the carbon material, a carbon graphite material classified as HCB-10T manufactured by Hitachi Chemical is adopted.

  The permanent magnet 31 is a plastic magnet formed into a cylindrical shape by kneading magnetic powder into a thermoplastic resin material such as PPS, and is directly formed on the outer periphery of the rotating shaft 27 by injection molding or the like. The permanent magnet 31 forms eight magnetic pole portions 34 in the rotation direction. The eight magnetic pole portions 75 are magnetized so as to form different magnetic poles alternately in the rotational direction on the outer peripheral surface facing the stator core 30.

  A shaft portion on one end side of the rotation shaft 27 is provided with a pin portion 35 that is pressed against the rotation shaft 27 and defines the axial position of the rotation shaft 27. The pin part 35 is made of martensitic stainless steel as a passive film regenerating material.

  The housing 36 serves as both the housing for the pressure feeding unit 18 and the driving unit 19. The housing 36 is formed by caulking the lower case 21 and the end cover 37 at both ends in the axial direction. The housing 36 is formed of austenitic stainless steel as a passive film regeneration material.

  The upper case 20 is abutted against the step 36 a of the housing 36 in the axial direction. Thereby, the upper case 20 is positioned in the axial direction. A bearing portion 32 is installed at the center of the upper case 20 by press-fitting. The lower case 21 is fixed by caulking at one end side of the housing 36, and the axial pressure generated by the caulking causes a surface pressure to press the upper case 20 and the stepped portion 36a and the lower case 21 and the upper case 20 in the axial direction. Secure and seal with urea water.

  The urea water pumped to the drive unit 19 side is sent out in the order of the flow passage 38 between the stator core 25 and the rotor 26 and the discharge passage 39, and is supplied from the discharge port 40 to the injection valve 6 side. When urea water flows through the flow path 38 as the inside of the drive unit, heat is generated between each surface facing the stator core 25 and the rotor 26 constituting the flow path wall of the flow path 38 and the urea water. Exchange is performed and the urea water receives heat. The discharge port 40 of the discharge passage 39 that opens to the outside from the end cover 37 is formed eccentrically with respect to the bearing portion 33.

  4 is a cross-sectional view taken along the line II of the urea water pressure pump 9 shown in FIG. Each core 30 has a tooth 41 and an outer peripheral portion 42, and is integrally formed by caulking and fixing electromagnetic stainless steel plates laminated in the axial direction of the rotating shaft 27. The teeth 41 protrude from the central portion of the outer peripheral portion 42 toward the inner rotor 26. Each core 30 is fitted with a bobbin 28 formed of an insulating resin. The outer peripheral portion 42 is formed in an arc shape having the same width in the circumferential direction, and the six outer peripheral portions 42 form an annular core.

  The coil 29 is formed by concentrating windings for each core 30 on the outer periphery of the bobbin 28 in a single state before the six cores 30 are installed in the circumferential direction to form the stator core 25. Each coil 29 is electrically connected to the terminals 43 and 44 on the end cover 37 side shown in FIG. The terminal 43 is taken out of the end cover 37 from a portion electrically connected to the coil 29, exposed, and connected to the connector. The terminal 44 is not exposed from the end cover 37 and is used for electrically connecting the coils 29 to each other.

  The insulating resin material 45 is filled between the teeth 41 adjacent to each other in the circumferential direction, is resin-molded so as to cover the coil 29, and is an end that covers the end of the stator core 25 opposite to the pressure-feeding portion 18. The cover 37 is integrally formed. As the material of the insulating resin material 45, PPS (polyphenylene sulfide) or POM (polyacetal) is suitable. In the end cover 37, the bearing portion 33 that supports the rotary shaft 27, the support portion of the terminal 43, and the discharge port 40 are integrally formed of an insulating resin material 45.

  The end cover 37 is formed with a bearing portion 33 for bearing the rotary shaft 27 at the center. The bearing portion 33 directly supports the rotary shaft 27 and the bottom portion is closed. Further, a discharge passage 39 is formed in the end cover 37 so as to be eccentric from the rotary shaft 27. The discharge passage 39 is formed linearly through the end cover 37 in the axial direction, and is in direct communication with the bearing portion 33.

  The fall prevention member 46 is formed in an annular shape having a through hole in the center, and is locked to the end of the bobbin 28 on the side opposite to the urea water pressure pump 9. The fall prevention member 46 has a fitting hole into which the terminals 43 and 44 are fitted. Since the insulating resin material 45 is resin-molded in a state in which the terminals 43 and 44 are fitted in the fitting holes, the terminals 43 and 44 are provided so as to prevent the terminals 43 and 44 from falling down and interfering with surrounding parts. .

  A check valve 47, a stopper 48 and a spring 49 are accommodated in the discharge port 40 formed by the end cover 37. When the urea water increased in pressure by the pressure feeding unit 18 reaches a predetermined pressure or more, the check valve 47 lifts against the load of the spring 49 and the urea water is discharged from the discharge port 40 to the injection valve 6 side. The check valve 47 is provided so as to prevent the back flow of the urea water discharged from the urea water pressure pump 9.

(Action / Effect)
When the internal combustion engine is started at a low temperature, the urea water from the urea water tank 8 is pressurized and fed toward the injection valve by the urea water pumping pump 9. Specifically, the ECU determines from the detection value of the temperature sensor 12 whether the urea water in the urea water tank 8 is in a flowable state. When it is determined that the urea water can flow, a signal for driving the urea water pressure feed pump is output from a drive circuit provided in the ECU.

  By driving the urea water pressure pump, urea water is sucked from the strainer 17, guided to the suction part 24, boosted in the pump passage 23 of the pressure feed part 18, and then pumped to the flow path 38 of the drive part 19. . In this way, a part of the energized energy energized to magnetize the stator core 25 to the coil 29 is converted into thermal energy by urea water flowing through the pumping unit 18 and the drive unit 19, so that the stator core Increase the temperature of 25. The main heat generation is a temperature rise of the coil 29 itself, and heat is transferred from the coil 29 to the stator core 25.

  Another heat generation in the drive unit 19 is that the stator core 25 is fixed and flows through a flow passage 38 as a gap flow path provided between the stator core 25 and the rotor 26 under a situation where the rotor 26 rotates at high speed. There is a stirring heat of urea water generated by doing so. As a configuration in which uneven projections that generate turbulent flow are provided on the relative surfaces of the stator core 25, the stator core 25, and the rotor 26 that constitute the flow passage 38, the above-described stirring heat may be increased.

  The urea water that has passed through the flow passage 38 rises in temperature than the urea water sucked from the strainer 17 and is pumped to the injection valve 6 via the discharge port 40 and the delivery pipe 7. When the discharge port 40 and the delivery pipe 7 are circulated, even if the discharge port 40 and the delivery pipe 7 freeze the urea water, the urea water whose temperature has been increased is frozen. The injection valve 6 can be reached in a desired pressure state without doing so.

  The ECU 10 adjusts and outputs a signal for driving the urea water pressure feed pump 9 from the drive circuit so that the detection value of the pressure sensor 13 becomes a desired pressure.

  The portion of the drive unit 19 that is exposed to the urea water when the urea water circulates inside is formed of a urea-resistant component (corrosion-resistant component) having corrosion resistance and oxidation resistance to the urea water. In a situation where it is exposed to urea water for a long time, the pressure feeding performance of urea water can be maintained well.

  The urea-resistant component (corrosion-resistant component) employed in the present invention is exposed to urea water to form a passive film at the surface portion exposed to urea water. A urea-resistant component containing a passive metal is employed in the lower layer of the surface portion.

  The passive film is a dense ultrathin (10 angstrom) oxide film formed on the surface portion. Even if this extremely thin oxide film is lost, if the surface portion is exposed to urea water, the oxide film is immediately regenerated and the corrosion resistance and oxidation resistance can be stabilized. In stainless steel, chromium in the lower layer on the surface portion forms a chromium oxide film. Examples of the urea-resistant constituent material that forms a passive film include nickel, chromium, iron, cobalt, titanium, tantalum, niobium, and alloys thereof in addition to stainless steel.

  Since both the upper case 20 and the lower case 21 are made of the same passive film reclaimed material, the same linear expansion coefficient is set as the pump case, and the upper case 20 and the lower case in a cold environment are set. The dimension of the pump chamber formed by the mating surface with 21 is stabilized. Thereby, pump performance can be stabilized.

  Since the upper case 20 and the lower case 21 are formed of austenitic stainless steel, they can be easily processed with high accuracy in their formation, and have excellent corrosion resistance and oxidation resistance against urea water. Can be demonstrated.

  The pin portion 35 is used in a situation where one shaft end portion of the rotating shaft is pressed against the urea water while being exposed to urea water. However, since the pin portion 35 is formed of martensitic stainless steel, the rotating shaft 27 is used. It is possible to exhibit wear resistance against pressing and excellent corrosion resistance and oxidation resistance to urea water.

  Since the stator core 25 is formed of electromagnetic stainless steel having excellent electromagnetic properties, the stator core 25 has excellent electromagnetic properties and can exhibit excellent corrosion resistance and oxidation resistance against urea water.

  The bearing portions 32 and 33 are made of a carbon material that is exposed to the urea water while supporting the rotary shaft 27 and is not exposed to the urea water and melted away from the surface portion thereof to stabilize the slidability. Since it is formed, the rotation of the rotating shaft 27 can be stabilized.

  At present, the practical application of the urea SCR system for in-vehicle diesel engines is being studied. However, the practical application of the urea SCR system for other engines such as gasoline engines (spark ignition engines) Is possible. Further, the present invention can be similarly applied to an exhaust purification system using a reducing agent other than urea water and having a oxidizing agent and corrosiveness similar to that of urea water.

  In the above-described embodiment, the urea water pressure pump 9 as an in-tank pressure pump in which the pressure pump is accommodated in the urea water tank 8 is shown. However, the pressure pump is disposed outside the urea water tank 8, that is, the injection pump. You may employ | adopt for the in-line type urea water pressure feed pump arrange | positioned on the delivery pipe | tube 7 which leads to the valve 6. FIG. FIG. 5 shows an example employed in an in-line type urea water pressure pump. The urea water pressure pump 90 shown in FIG. 5 has a configuration in which urea water flows through each part of the pressure feeding unit 18 and the drive unit 19 and is exposed to the urea water, like the urea water pressure pump 9 shown in FIG. .

(Other configuration of urea water pressure pump)
In the urea water pressure pump 9 described above, the stator core 25 constituting the drive unit 19 is formed of electromagnetic stainless steel having excellent electromagnetic characteristics, but this can be changed as follows. That is, the stator core 25 is formed of a silicon steel plate generally used as a magnetic material for a stator, and a resin coating layer having corrosion resistance and oxidation resistance against urea water on the surface (stator core surface layer portion) of the silicon steel plate. Form.

  The specific configuration will be described with reference to FIGS. 6 to 9 exemplify a plurality of configurations for forming a resin coating layer on the stator core surface layer portion, (a) of each figure shows its appearance, and (b) shows its internal structure. ing.

  In FIG. 6, the silicon steel plate 25 a is individually resin-molded, and a large number of them are laminated to constitute the stator core 25. That is, around each silicon steel plate 25a, a resin coating layer 25b made of a thermoplastic resin such as PPS (polyphenylene sulfide) is formed, and the stator core 25 is configured by laminating many of them.

  In FIG. 7, the stator core 25 is configured by resin molding a laminate in which a large number of silicon steel plates 25 a are laminated. That is, a resin coating layer 25b made of a thermoplastic resin such as PPS is formed around the laminated body made up of many silicon steel plates 25a.

  In FIG. 8, it is set as the structure which assemble | attaches the coil | winding and a terminal to the stator core 25 which consists of a several core, and integrally molds the integral thing. That is, a plurality of (six in this embodiment) cores formed by laminating a large number of silicon steel plates are annularly arranged, and windings (coils 29) and terminals 43 are assembled to the cores. These integrals are resin-molded. Thereby, the stator core 25 and the cylindrical resin body 51 are integrally formed, and the stator core 25 is covered with the resin body 51. In this case, a resin coating layer is formed by the resin body 51 on the surface layer portion of the stator core 25. A hollow portion 51a for accommodating the rotor 26 (see FIG. 3) composed of the rotating shaft 27 and the permanent magnet 31 and forming a urea water flow passage is formed in the central portion of the resin body 51. The resin body 51 is made of a thermoplastic resin such as PPS.

  In FIG. 9, windings and terminals are assembled to a stator core 25 made up of a plurality of cores, the integrals thereof are collectively resin-molded, and a urea water discharge part is integrally formed. That is, a plurality of (six in this embodiment) cores formed by laminating a large number of silicon steel plates are annularly arranged, and windings (coils 29) and terminals 43 are assembled to the cores. These integrals are resin-molded. Thereby, the stator core 25 and the cylindrical resin body 52 are integrally formed, and the stator core 25 is covered with the resin body 52. In this case, a resin film layer is formed on the surface layer portion of the stator core 25 by the resin body 52. In the resin body 52, a hollow portion 52a for housing the rotor 26 (see FIG. 3) including the rotating shaft 27 and the permanent magnet 31 and forming a urea water flow passage is provided at the center portion, and the axial direction An end cover 37 is provided on one end side. The end cover 37 is provided with a discharge passage 39 and a discharge port 40. The resin body 52 is formed of a thermoplastic resin such as PPS.

  In any of the configurations of FIGS. 6 to 9 described above, the silicon steel plate constituting the stator core 25 is completely molded in the resin, so that the silicon steel plate can be prevented from being directly exposed to urea water. Therefore, the corrosion resistance and oxidation resistance of the stator core 25 can be improved.

  6 to 9 described above, the silicon steel plate constituting the stator core 25 is completely molded in the resin. However, this may be changed so that a part of the silicon steel plate is not resin-molded. Good. A stator structure having such a configuration is shown in FIG.

  In FIG. 10 (a), as in FIG. 9 described above, windings and terminals are assembled to the stator core 25 composed of a plurality of cores, the integrals are collectively molded with resin, and the urea water discharge part is formed integrally. It is configured. That is, a plurality of (six in this embodiment) cores formed by laminating a large number of silicon steel plates are annularly arranged, and windings (coils 29) and terminals 43 are assembled to the cores. These integrals are resin-molded. Thereby, the stator core 25 and the cylindrical resin body 53 are integrally formed, and the stator core 25 is covered with the resin body 53 (in this configuration, the portion other than the outer peripheral portion is covered). In this case, a resin film layer is formed by the resin body 53 on the inner peripheral surface layer portion of the stator core 25. In the resin body 53, a hollow portion 53a for accommodating the rotor 26 (see FIG. 3) including the rotating shaft 27 and the permanent magnet 31 and forming a urea water flow passage is provided at the center portion, and the axial direction An end cover 37 is provided on one end side. The end cover 37 is provided with a discharge passage 39 and a discharge port 40. The resin body 53 is formed of a thermoplastic resin such as PPS.

  Here, the configuration of FIG. 10A is different from the configuration of FIG. 9 in that no resin coating layer is provided on the outer peripheral side of the stator core 25. In such a configuration, the resin film layer can be reduced by removing a part of the resin coating layer, and the resin coating process can be simplified. On the other hand, the outer periphery of the stator core (specifically, the resin body and the housing on the outer periphery thereof) There is a concern that the stator core 25 may be eroded by the urea water that has entered from the boundary portion.

  Therefore, a resin cylinder portion 54 is formed integrally with the resin body 53 at an axial end portion of the stator core 25 (on the side opposite to the terminal 43 and the discharge port 40 in the figure), and an outer peripheral portion of the resin cylinder portion 54 is formed. In addition, an annular groove 54a forming a part of the seal structure is formed. A sealing material 57 is arranged in the annular groove 54a (details will be described later in FIG. 11).

  Further, it is desirable that the permanent magnet 31 constituting the rotor 26 has a structure in which a resin film layer is formed on the surface layer portion, and such a structure is shown in FIG. In FIG. 10 (b), a magnet body 55 having a cylindrical outer shape and a permanent magnet 31 embedded therein is provided around the rotation shaft 27. The magnet body 55 has a first resin layer 56a and a second resin layer 56b provided so as to sandwich the permanent magnet 31 from inside and outside, and each of these resin layers 56a and 56b corresponds to a resin coating layer. Of the first resin layer 56a and the second resin layer 56b, the outer second resin layer 56b is preferably thin in order to make the gap with the stator core 25 as small as possible.

  In such a case, the rotor 26 is manufactured by the following procedure. First, the first resin layer 56a is primarily formed on the rotary shaft 27, and then the permanent magnet 31 made of a ferromagnetic material is assembled on the outer periphery of the first resin layer 56a. Then, the second resin layer 56b is secondarily molded so as to completely surround the first resin layer 56a and the permanent magnet 31.

  A protrusion-like heat-welded portion (A portion in the figure) is formed at the axial end of the first resin layer 56a that is primarily molded, and the first resin layer 56a is formed during the secondary molding of the second resin layer 56b. It is preferable that the heat welded portion is integrated by melting. Thereby, the internal penetration of urea water through the boundary part of each resin layer 56a, 56b can be prevented more reliably.

  As described above, the permanent magnet 31 is resin-molded in the magnet body 55, so that the permanent magnet 31 can be reliably isolated from the urea water. Therefore, the permanent magnet 31 can have good corrosion resistance and oxidation resistance.

  FIG. 11 shows a cross-sectional structure of a urea water pressure feed pump 60 configured by using the stator structure of FIG. 10A and the rotor 26 of FIG. The urea water pressure pump 60 in FIG. 11 has the same basic structure as the urea water pressure pump 9 (see FIG. 3) described above. Omits the explanation.

  As shown in FIG. 11, the stator structure shown in FIG. 10A is accommodated in a cylindrical housing 36, and the rotor 26 is rotatable in the hollow portion 53 a of the resin body 53 in the stator structure. Is housed in. A sealing material 57 such as an O-ring is disposed in an annular groove 54 a of the resin cylinder portion 54 provided integrally with the resin body 53, and the resin cylinder portion 54 (resin body 53) and the housing 36 are arranged by the seal material 57. The contact surface with is sealed. That is, the urea water that has passed through the pressure feeding unit 18 is prevented from entering the stator core 25 side along the inner peripheral surface of the housing 36.

  In each of the above-described configurations (FIGS. 6 to 11), a resin coating layer having corrosion resistance and oxidation resistance against urea water is formed on the surface layer portion of the stator core 25. It is good also as a structure which forms the surface treatment layer which has the corrosion resistance with respect to urea water, and oxidation resistance in a surface layer part. Specifically, for example, at least one of nickel plating and electrodeposition coating is performed as the surface treatment layer. Even in this configuration, as described above, excellent effects on corrosion resistance and oxidation resistance can be obtained.

  In each of the above-described configurations (FIGS. 6 to 11), a resin coating layer (or surface treatment layer) is formed on the surface layer portion of the stator core 25, thereby improving the corrosion resistance of the stator core 25. It is also possible to assemble a cylindrical isolation member for isolating the stator core 25 and the urea water flow passage to the stator 25, thereby improving the corrosion resistance of the stator core 25.

  Specifically, as shown in FIG. 12, the stator structure 71 is obtained by assembling a winding (coil 29) and a terminal 43 to a stator core 25 composed of a plurality of cores, and integrally assembling a resin body 72 thereon. In the stator structure 71, the stator core 25 (silicon steel plate) is exposed on the inner peripheral side. A cylindrical partition member 73 (cylindrical separating member) made of a thermoplastic resin such as PPS is disposed on the inner peripheral portion of the stator structure 71.

  The cylindrical partition member 73 includes a cylindrical portion 74 and a flange portion 75, and the cylindrical partition member 73 is formed on the inner peripheral surface of the stator core 25 because the outer diameter of the cylindrical portion 74 substantially matches the inner diameter of the stator core 25. It can be assembled without gaps. A rotor 26 (see FIG. 3) including the rotary shaft 27 and the permanent magnet 31 is accommodated in the cylindrical portion 74, and a urea water flow passage is formed.

  An annular groove 72a is formed in a contact portion of the resin body 72 with the cylindrical partition member 73, and a sealing material 76 such as an O-ring is disposed in the annular groove 72a. An annular groove 75a is formed on the outer periphery of the flange portion 75, and a sealing material 77 such as an O-ring is disposed in the annular groove 75a. Therefore, the contact surfaces between the stator structure 71 and the outer periphery of the flange portion 75 are sealed by the sealing materials 76 and 77. That is, the urea water is prevented from entering the stator core 25 through the gap between the stator structure 71 and the cylindrical partition member 73.

  According to the configuration of FIG. 12, by providing the cylindrical partition member 73 that separates the stator core 25 and the urea water flow passage, it is possible to suppress the silicon steel plate of the stator core 25 from being directly exposed to the urea water. Therefore, the corrosion resistance and oxidation resistance of the stator core 25 can be improved.

  Further, in the configuration in which the resin coating layer is provided on the stator core surface layer as described above, or in the configuration in which the cylindrical isolation member is assembled to the stator core, a heating element is disposed on the resin coating layer or the cylindrical isolation member. The urea water flowing through the urea water flow passage may be heated. In this case, of the resin coating layer around the stator core, the heating element is embedded in the resin coating layer on the urea water flow path side. Alternatively, a heating element is embedded in the cylindrical isolation member.

(Urea water thawing control)
Next, urea water thawing control in the urea water supply system will be described. In this control, when the urea water is frozen, the frozen urea water is defrosted by the heat generated by the coil of the urea water pressure pump. In this case, in particular, the coil is energized with a current value higher than that during normal use to promote thawing. FIG. 13 is a flowchart showing a processing procedure related to urea water thawing control, and this processing is executed by the ECU 10 after the engine is started. Refer to the system configuration in FIG. 1 for sensors and the like used in the following processing.

  In FIG. 13, in step S11, the temperature of the urea water is detected based on the detection signal of the temperature sensor 12, and in the subsequent step S12, it is determined whether or not the urea water temperature is equal to or lower than a predetermined freezing temperature (−11 ° C.). To do. If urea water temperature> freezing temperature, the process proceeds to step S15, and normal operation of the urea water pressure pump is executed. That is, when the urea water is not frozen, a current of a normal level is supplied to the coil of the drive unit of the urea water pressure pump, thereby causing the pump to normally operate.

  If the urea water temperature is equal to or lower than the freezing temperature, the process proceeds to step S13, and the high output operation of the urea water pressure feed pump is executed. That is, when the urea water is frozen, a high-level current (a current for thawing urea water that is higher than the normal level) is supplied to the coil of the urea water pressure pump drive unit. The pump is operated at high power.

  In step S14, a pressure increase in the urea water delivery pipe is determined. Specifically, the supply pressure of the urea water is detected based on the detection signal of the pressure sensor 13, and it is determined whether or not the supply pressure has reached a predetermined threshold value or more. If the pressure in the urea water delivery pipe has not increased, it is assumed that the urea water has not been thawed, and the process returns to step S11 and the above-described processes are executed again. Further, if the pressure in the urea water delivery pipe has increased, it is considered that the urea water has been thawed, and the routine proceeds to step S15 to perform the normal operation of the urea water pressure pump.

  According to the above control, even if the urea water freezes in a cold district or the like, the urea water pressure pump is operated at a high output, so that the heat generation amount of the pump can be increased and the thawing of the urea water can be promoted. As a result, the frozen urea water can be thawed quickly, and thus suitable exhaust purification can be realized.

(Another example of using reducing agents other than urea water)
In each of the above-described embodiments, the case where urea water is used as the liquid reducing agent has been described. However, other reducing agents can be used as the reducing agent, and the present invention can be used when other reducing agents are used. Is useful.

  For example, in an exhaust purification system that includes a NOx occlusion reduction catalyst in an exhaust pipe, a fuel injection nozzle is also provided in the exhaust pipe, and fuel as a reducing agent is injected and supplied from the fuel injection nozzle to the upstream side of the NOx occlusion reduction catalyst. Is done. The stored NOx of the NOx storage reduction catalyst is reduced and purified by the fuel injected and supplied from the fuel injection nozzle. In addition, as fuel used as a reducing agent, there are alcohol fuels (including so-called biodiesel fuel) in addition to diesel oil generally used as diesel engine fuel.

  In the system using fuel as the reducing agent as described above, the configuration is substantially the same as that shown in FIG. 1. In FIG. 1, reference numeral 3 is a NOx storage reduction catalyst, reference numeral 6 is a fuel injection nozzle, reference numeral 8 is a fuel tank, reference numeral 9 is a fuel pump (reducing agent pump). Further, the configuration of the fuel pumping pump (FIGS. 3, 4 and 6 to 12) can be used as it is. That is, the present invention can be applied to a fuel pump.

It is a whole lineblock diagram showing the whole urea SCR system composition in an embodiment of the present invention. It is a block diagram which shows the detailed structure of the urea water supply part shown in FIG. It is a block diagram which shows the detailed structure of the urea water pressure pump shown in FIG. It is the II sectional view taken on the line of the urea water pressure pump shown in FIG. It is a whole lineblock diagram showing the whole line structure of an in-line type urea SCR system. It is a figure which shows the structural example of a stator core. It is a figure which shows the structural example of a stator core. It is a figure which shows the structural example of a stator core. It is a figure which shows the structural example of a stator core. (A) is sectional drawing of a stator structure, (b) is sectional drawing of a rotor. It is sectional drawing of a urea water pressure pump. It is a figure which shows a stator structure. It is a flowchart which shows the process sequence regarding urea water defrost control.

Explanation of symbols

9 Urea water pressure pump (reducing agent pressure pump)
10 ECU (detection means, determination means, pump control means)
19 Electric drive (drive)
20 Upper case (part of pump case)
21 Lower case (part of pump case)
22 impeller (rotary pumping body, part of the mechanism)
23 Pump passage 25 Stator core (part of the electric drive unit)
25a Silicon steel plate 25b Resin coating layer 26 Rotor (part of the electric drive unit)
27 Rotating shaft Pin portion 31 Permanent magnet 32, 33 Bearing portion 36 Housing 38 Flow path 51, 52, 53 Resin body 54 Resin cylinder portion 55 Magnet body 56a, 56b Resin layer (resin coating layer)
60 Urea water pump (reducing agent pump)
73 Tubular partition member (tubular isolation member)
76, 77 Sealing material

Claims (28)

A pumping unit having a mechanism unit for pumping a liquid reducing agent;
A driving unit that generates a driving force for driving the mechanism unit to pump the reducing agent;
A flow path through which the reducing agent pumped out from the pumping unit flows through the driving unit,
The reducing agent pressure feed pump characterized in that the portion of the flow passage exposed to the reducing agent is formed of a corrosion-resistant component having corrosion resistance and oxidation resistance to the reducing agent.   The corrosion-resistant component is exposed to the reducing agent at the surface portion exposed to the reducing agent to form a passive film, and the metal oxide contained in the inner layer and the reducing agent are combined to form the passive film. The reducing agent pressure feed pump according to claim 1, wherein the reducing agent pressure feed pump is formed of a regenerated passive film regenerated material. The pumping unit is
A pump case that forms a pump chamber into which the reducing agent flows; and
A relative position with respect to the inner space of the pump chamber is defined and disposed in the pump chamber, and includes a rotary pumping body that pumps the reducing agent by its rotating operation,
The reducing agent pressure feed pump according to claim 2, wherein the pump case is formed of the passive film regenerated material. The pump case is provided with the pump chamber arranged so that a section screen that divides the chamber faces the inside of the mating surface to be joined, joining the two members of the upper case and the lower case,
4. The reducing agent pump according to claim 3, wherein both the upper case and the lower case are formed of the passive film regeneration material made of the same material. 5.   5. The reducing agent pump according to claim 4, wherein both the upper case and the lower case are made of austenitic stainless steel as the passive film regenerating material. The pumping unit is
A pump case for forming a pump chamber for flowing the reducing agent therein;
A relative pressure to the space in the pump chamber is defined by being fixed to a rotary shaft and is disposed in the pump chamber, and a rotary pumping body that pumps the reducing agent by its rotational operation;
A pin portion that is pressed against one shaft end of the rotating shaft and defines an axial position of the rotating shaft; and
The reducing agent pressure feed pump according to claim 2, wherein the pin portion is formed of the passive film regenerated material.   The reducing agent pump according to claim 6, wherein the pin portion is formed of martensitic stainless steel as the passive film regenerating material. The pumping unit includes a rotary pumping body that pumps the reducing agent by its rotating operation,
The drive unit includes a stator core that is exposed to the reducing agent while being rotated electromagnetically with respect to a rotor coupled by a rotary shaft with the rotary pump.
The reducing agent pressure feed pump according to claim 2, wherein the stator core is formed of the passive film regenerated material.   The reducing agent pump according to claim 8, wherein the stator core is made of stainless steel having excellent electromagnetic properties as the passive film regenerating material. Comprising a housing that constitutes a part of the outer shell and in which the outer shell is immersed in the reducing agent;
The reducing agent pressure feed pump according to claim 2, wherein the housing is formed of the passive film regenerated material.   11. The reducing agent pump according to claim 10, wherein the housing is made of austenitic stainless steel as the passive film regenerating material.   The reducing agent pressure-feed pump according to any one of claims 2, 3, 6, 8, and 10, wherein the passive film regenerated material is stainless steel. A rotary shaft disposed as a shaft body at a rotation center position of a rotary pumping body that pumps the reducing agent by a rotating operation;
A bearing portion that is exposed to the reducing agent while pivotally supporting the rotating shaft,
The reducing agent pressure feed pump according to claim 1, wherein the bearing portion is formed of the corrosion-resistant constituent material.   The corrosion-resistant constituent material constituting the bearing portion is formed of a carbon material that stabilizes slidability at the surface portion exposed to the reducing agent without being exposed to the reducing agent and melted away from the surface portion. The reducing agent pressure feed pump according to claim 13, wherein:   The corrosion-resistant component is a member in which a resin coating layer or a surface treatment layer having corrosion resistance and oxidation resistance to the reducing agent is formed on a surface portion exposed to the reducing agent. The reducing agent pressure feed pump according to 1. The pumping unit includes a rotary pumping body that pumps the reducing agent by its rotating operation,
The drive unit includes a stator core that rotates a rotor coupled to the rotary pumping body by a rotary shaft by being electromagnetically driven,
The reducing agent pump according to claim 15, wherein the resin coating layer or the surface treatment layer is formed on a surface layer portion of the stator core.   The reducing agent pressure feed pump according to claim 16, wherein the magnetic steel plate constituting the stator core is resin-molded. The stator core is housed in a housing member, the stator core is cylindrical, and the flow path is formed on the inner circumferential side thereof.
In the stator core, the resin coating layer is formed on the inner peripheral side of the stator core, and the resin cylinder portion is formed integrally with the resin coating layer at the axial end portion, and the outer periphery of the resin cylinder portion is formed. The reducing agent pressure feed pump according to claim 16 or 17, further comprising a seal structure for sealing a contact surface with the housing member. The pumping unit includes a rotary pumping body that pumps the reducing agent by its rotating operation,
The drive unit includes a stator core that rotates a rotor coupled to the rotary pumping body by a rotary shaft by being electromagnetically driven,
The stator core has a cylindrical shape, and is a reducing agent pressure feed pump in which the flow passage is configured on the inner peripheral side thereof,
The reducing agent pressure feed pump according to claim 15, wherein a cylindrical isolation member that isolates the stator core and the flow passage is provided as an anticorrosive component on the inner peripheral side of the stator core. A reducing agent pump that includes a magnet member that is exposed to the reducing agent in the drive unit and is provided to face the stator core;
The reducing agent pump according to any one of claims 16 to 19, wherein the resin coating layer or the surface treatment layer is formed on a surface layer portion of the magnet member.   21. The reducing agent pump according to claim 20, wherein the magnet member is resin-molded. A pumping unit having a mechanism unit for pumping a liquid reducing agent;
A driving unit that drives the mechanism unit to drive the reducing agent under pressure, and a driving unit that generates heat by generating the driving force;
A flow path through which the reducing agent pumped out from the pumping unit is circulated through the driving unit and the heat generation is received by the reducing agent;
A reducing agent pressure feed pump comprising: The drive unit is provided to generate a driving force that is energized to pump the reducing agent, and to generate heat due to the energization.
The reducing agent pressure feed pump according to claim 22, further comprising the flow passage provided so that the driving unit and the reducing agent are in contact with each other.   Each part of the pumping unit and the driving unit exposed to the reducing agent by the flow of the reducing agent is formed of a corrosion-resistant constituent material having corrosion resistance and oxidation resistance to the reducing agent. The reducing agent pump according to claim 22 or 23.   The corrosion-resistant component is exposed to the reducing agent at the surface portion exposed to the reducing agent to form a passive film, and the metal oxide contained in the inner layer and the reducing agent are combined to form the passive film. The reducing agent pressure feed pump according to claim 24, wherein the reducing agent pressure feed pump is formed of a regenerated passive film regenerated material.   26. The reducing agent pump according to claim 25, wherein the passive film regenerated material is stainless steel.   The reducing agent pressure feed pump according to any one of claims 1 to 26, wherein the reducing agent is urea water. A reducing agent thawing control device applied to a reducing agent supply system using the reducing agent pressure feed pump according to any one of claims 1 to 27,
Detecting means for detecting the temperature of the reducing agent;
Determination means for determining whether or not the reducing agent temperature detected by the detection means has reached a freezing temperature;
A pump control means for operating the reducing agent pump in a high output state for reducing agent thawing when it is determined by the determining means that the reducing agent temperature has reached the freezing temperature;
A reducing agent thawing control device comprising:

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