JP2017133698A - Chemical heat storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chemical heat storage device capable of detecting abnormality in a mobile system of a reaction medium and abnormality in a heater at an early stage.SOLUTION: A chemical heat storage device 10 which heats a heating object includes: a heater 11 having a heat storage material 11a for generating heat by chemically reacting with a reaction medium; a reservoir 12 for storing the reaction medium; a connection pipe 13 for connecting the heater 11 and the reservoir 12; an opening/closing valve 14 provided at the connection pipe 13; a control part 15 for controlling opening/closing of the opening/closing valve 14; an acquisition part 15 for acquiring a value regarding generating heat quantity of the heater 11 during heating; and an estimation part 15 for estimating the value regarding the generating heat quantity of the heater 11 from the amount of the reaction medium which can be supplied to the heater 11 from the reservoir 12. The control part 15 determines that it is abnormal in the case where a difference between the value regarding the generating heat quantity acquired by the acquisition part 15 and the value regarding the generating heat quantity estimated by the estimation part 15 is equal to or greater than a threshold value, in the case where opening control of the opening/closing valve 14 is performed for supplying the reaction medium to the heater 11.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a chemical heat storage device.

  Various exhaust purification catalysts such as an oxidation catalyst and a NOx catalyst are provided in an exhaust system of a vehicle or the like in order to purify environmental pollutants (HC, CO, NOx, etc.) contained in exhaust gas exhausted from an engine. ing. Since these exhaust purification catalysts exhibit a high purification ability at or above the activation temperature, for example, when the temperature of the catalyst is low, such as during engine cold start, it is necessary to raise the temperature above the activation temperature at an early stage. Therefore, it has been considered to provide a heating device in the exhaust system for warming up the catalyst at the time of engine cold start or the like and raising the temperature to the activation temperature or higher at an early stage. As this type of heating device, there is known a chemical heat storage device that uses the heat of a chemical reaction between a reaction medium and a heat storage material that can warm up the catalyst while reducing energy loss (fuel consumption loss). Yes. For example, Patent Document 1 discloses a chemical heat storage device for warming up a catalyst as a heating target provided in a vehicle exhaust system, and a reaction having a reaction material (heat storage material) provided on an outer peripheral portion of the catalyst. It is disclosed that a heater (heater) and a reservoir for storing ammonia as a reaction medium are connected via a pipe line, and an open / close valve is provided in the pipe line.

JP 2013-242053 A

  When warming up the object to be heated by reacting ammonia with the heat storage material with a heater or when recovering ammonia desorbed from the heat storage material with a storage device, a desired amount of ammonia is added to the heater and storage device. Move between. At this time, the on-off valve provided in the pipe line is controlled to open, and ammonia can be moved through the pipe line. However, for example, when an abnormality occurs in the ammonia moving path (moving system) such as a failure of an on-off valve or a clogged pipe, the movement of ammonia between the heater and the reservoir is hindered. In addition, when an abnormality occurs in the heater such as ammonia leakage due to breakage of the heater or deterioration of the heat storage material, the reactivity in the heater decreases. In such a case, it is impossible to warm up or recover ammonia as intended.

  Therefore, in this technical field, there is a demand for a chemical heat storage device that can detect an abnormality in a moving system of a reaction medium and an abnormality in a heater at an early stage.

  A chemical heat storage device according to one aspect of the present invention is a chemical heat storage device that heats an object to be heated, includes a heat storage material that chemically reacts with a reaction medium to generate heat, and heats the object to be heated. And a reservoir for storing the reaction medium, a heater and a reservoir, a connection pipe through which the reaction medium flows, an on-off valve provided in the connection pipe, a controller for controlling opening and closing of the on-off valve, and heating An acquisition unit that acquires a value related to the amount of heat generated by the heater when the object is heated, and an estimation unit that estimates a value related to the amount of generated heat of the heater from the amount of reaction medium that can be supplied from the reservoir to the heater, When the control unit performs open control of the on-off valve to supply the reaction medium from the reservoir to the heater, the difference between the value related to the generated heat amount acquired by the acquiring unit and the value related to the generated heat amount estimated by the estimating unit The determination process to determine that there is an abnormality when is over the threshold Cormorant.

  In this chemical heat storage device, the acquisition unit acquires a value related to the actual generated heat amount of the heater, and the estimation unit estimates a value related to the generated heat amount of the heater from the amount of reaction medium that can be supplied to the heater. If the reaction medium cannot move to the heater due to an abnormality in the reaction medium movement system, or if the reactivity of the heater is reduced due to an abnormality in the heater, the heater estimated from the amount of reaction medium that can be supplied Compared to the amount of heat generated, the actual amount of heat generated in the heater is reduced. In this case, the temperature rise of the heater or the heating object is small. On the other hand, when the reaction medium can move to the heater and the reactivity in the heater is not lowered, the estimated generated heat amount and the actual generated heat amount are substantially the same. In this case, the temperature of the heater, the heating object, etc. rises according to the actual amount of heat generated. Therefore, in the chemical heat storage device, when the difference between the value related to the actual generated heat quantity and the value related to the estimated generated heat quantity is equal to or greater than the threshold value, it is determined that there is an abnormality in the moving system of the reaction medium or the heater abnormality early. Can be detected.

  In the chemical heat storage device of one embodiment, the value relating to the amount of generated heat includes the rising temperature of the heater that rises according to the amount of generated heat, the rising temperature of the heating object that rises according to the amount of generated heat, and the heating that rises according to the amount of generated heat. It is the rising temperature of any of the rising temperatures of the fluid flowing inside the object. In addition, the value regarding the generated heat quantity may be the generated heat quantity of the heater itself.

  In the chemical heat storage device of one embodiment, the chemical heat storage device is mounted on a vehicle having an engine as a drive source, and heats an object to be heated in an exhaust system of the vehicle, and detects the temperature of exhaust gas downstream of the heater. A downstream temperature detection unit, and the acquisition unit acquires the rising temperature from the temperature of the downstream exhaust gas detected by the downstream temperature detection unit. Furthermore, the chemical heat storage device of one embodiment includes an upstream temperature detection unit that detects the temperature of the exhaust gas upstream of the heater, and the acquisition unit detects the downstream exhaust gas detected by the downstream temperature detection unit. The rising temperature is acquired from the temperature difference obtained by subtracting the temperature of the upstream exhaust gas detected by the upstream temperature detector from the temperature.

  In this chemical heat storage device, by using only the temperature of the exhaust gas downstream of the heater detected by the downstream temperature detection unit, the rising temperature of the heater or the like can be acquired with a simple configuration. Further, in the chemical heat storage device, by using the temperature of the exhaust gas upstream of the heater detected by the upstream temperature detector in addition to the temperature of the exhaust gas downstream of the heater detected by the downstream temperature detector. The rising temperature of the heater or the like can be obtained with high accuracy.

  In the chemical heat storage device of one embodiment, the control unit performs a determination process when the opening / closing valve is controlled to open at the time of starting the engine. Before starting the engine, the temperature of the exhaust gas is low and the temperature of the heater is also low. Further, before starting the engine, a large amount of reaction medium is stored in the storage device, so that a large amount of reaction medium can be supplied to the heater, and the amount of heat generated by the heater increases. Therefore, at the time of starting the engine, the determination using the value related to the amount of heat generated by the heater can be performed with high accuracy.

  In the chemical heat storage device of one embodiment, the estimation unit obtains a storage amount of the reaction medium stored in the reservoir, acquires an amount of the reaction medium that can be supplied to the heater from the storage amount of the reaction medium, and A value related to the amount of heat generated by the heater is estimated from the amount of reaction medium that can be supplied. In this way, a value related to the amount of heat generated by the heater can be easily estimated.

  The chemical heat storage device of one embodiment includes a reservoir temperature detection unit that detects the temperature of the reservoir and a reservoir pressure detection unit that detects the pressure of the reservoir, and the estimation unit is detected by the reservoir temperature detection unit. The storage amount of the reaction medium is obtained using the detected temperature and the pressure detected by the storage pressure detector. Thus, the storage amount of the reaction medium stored in the reservoir can be easily obtained from the temperature and pressure of the reservoir.

  According to the present invention, it is possible to detect an abnormality in the reaction medium moving system and an abnormality in the heater at an early stage.

It is a schematic block diagram of the exhaust gas purification system provided with the chemical heat storage apparatus which concerns on one Embodiment. It is a graph which shows the relationship between the ammonia supply amount and generated heat amount in the heater of FIG. FIG. 2 is a graph showing the relationship between parameters for storage shown in FIG. 1, (a) is a graph showing the relationship of storage temperature-ammonia saturated vapor pressure, and (b) is a relative pressure (= storage pressure / ammonia saturated vapor pressure). It is a graph which shows the relationship of ammonia adsorption amount. It is a conceptual diagram which shows the operation | movement after opening a valve | bulb at the time of warming-up of the chemical thermal storage apparatus shown in FIG. It is a flowchart which shows the operation | movement of the abnormality detection at the time of warming-up in the chemical thermal storage apparatus shown in FIG.

  Hereinafter, a chemical heat storage device according to an embodiment of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected about the element which is the same or it corresponds in each figure, and the overlapping description is abbreviate | omitted.

  A chemical heat storage device according to an embodiment is applied to a chemical heat storage device provided in an exhaust gas purification system provided in an exhaust system of a vehicle engine. An exhaust gas purification system according to an embodiment is a system that purifies harmful substances (environmental pollutants) contained in exhaust gas discharged from an engine (particularly a diesel engine), and is a catalyst DOC [Diesel Oxidation Catalyst]. SCR [Selective Catalytic Reduction], ASC [Ammonia Slip Catalyst], and DPF [Diesel Particulate Filter] of the filter. The exhaust gas purification system according to an embodiment also includes a chemical heat storage device for warming up, and the chemical heat storage device is provided in a heat exchanger disposed between the engine and the DOC.

  With reference to FIG. 1, the whole structure of the exhaust-gas purification system 1 which concerns on one Embodiment is demonstrated. FIG. 1 is a schematic configuration diagram of an exhaust gas purification system 1 according to an embodiment.

  The exhaust gas purification system 1 includes a heat exchanger 4, a diesel oxidation catalyst (DOC) 5, a diesel exhaust particulate removal filter (DPF) from the upstream side to the downstream side of the exhaust pipe 3 connected to the exhaust side of the engine 2. 6. A selective reduction catalyst (SCR) 7 and an ammonia slip catalyst (ASC) 8 are provided. Each part where these heat exchangers 4, DOC5, DPF6, SCR7, and ASC8 are arranged is larger than the diameter of the exhaust pipe 3 where the parts are not arranged. Exhaust gas discharged from the engine 2 flows inside the exhaust pipe 3 and the heat exchanger 4, DOC5, DPF6, SCR7, and ASC8, and the upstream side and the downstream side are defined by the direction in which the exhaust gas flows.

  The heat exchanger 4 is a device that exchanges (transfers) heat between exhaust gas discharged from the engine 2 and a heater 11 described later. The heat exchanger 4 is formed of a metal material having high thermal conductivity, and the inside of the outer cylinder has a honeycomb structure. The heat exchanger 4 is not limited to the honeycomb structure, and a known heat exchange structure can be applied.

The DOC 5 is a catalyst that oxidizes HC, CO, and the like contained in the exhaust gas. The DPF 6 is a filter that collects and removes PM contained in the exhaust gas. When SCR 7 is supplied with ammonia (NH ₃ ) or urea water (hydrolyzed into ammonia) to the upstream side of the exhaust pipe 3 by the injector 7 a, the SCR 7 chemically reacts with NOx contained in the exhaust gas. This is a catalyst that reduces and purifies NOx. The ASC 8 is a catalyst that oxidizes ammonia that has passed through the SCR 7 and has flowed downstream.

  Each catalyst 5, 7, 8 has a temperature range (that is, an activation temperature) that can exhibit a purification ability against environmental pollutants. However, immediately after the engine 2 is started, the temperature of the exhaust gas immediately after being discharged from the engine 2 is relatively low and may be lower than its activation temperature. Thus, even immediately after the engine 2 is started, the temperature at each of the catalysts 5, 7, and 8 needs to be quickly brought to the active temperature in order to exert the purification capability at each of the catalysts 5, 7, and 8. For this purpose, the exhaust gas purification system 1 includes a chemical heat storage device 10 that heats the most upstream heat exchanger 4 (exhaust gas flowing inside) and warms up the catalyst.

  The chemical heat storage device 10 is a chemical heat storage device that warms up an object to be heated such as a catalyst without external energy. Specifically, the chemical heat storage device 10 stores a reaction medium that stores heat from an object to be heated and desorbs from the heat storage material, and supplies the stored reaction medium to the heat storage material when necessary. In this way, the heat storage material and the reaction medium are chemically reacted, and the object to be heated is heated using reaction heat (heat radiation) during the chemical reaction. That is, it can be said that the chemical heat storage device 10 uses a reversible chemical reaction to store heat from the object to be heated and supply heat to the object to be heated. In this embodiment, the chemical heat storage device 10 heats the heat exchanger 4 disposed on the upstream side of the DOC 5 that is the catalyst located on the most upstream side. Exhaust gas flows inside the heat exchanger 4 and is configured to exchange heat with the exhaust gas. Therefore, by disposing the chemical heat storage device 10 on the most upstream side of the pipe through which the exhaust gas flows (the side close to the engine 2), the exhaust gas in a state where the temperature at the time of starting the engine 2 is not so high is converted into a heat exchanger. The temperature can be quickly raised before reaching the catalyst (DOC5, SCR7, ASC8) disposed downstream of the No.4. In this embodiment, the heat exchanger 4 corresponds to the heating object described in the claims.

  The chemical heat storage device 10 includes a heater 11, a storage 12, a connecting pipe 13, a valve 14, and the like, and is controlled by a controller 15. In this embodiment, the heater 11 corresponds to the heater described in the claims, the storage 12 corresponds to the reservoir described in the claims, and the connecting pipe 13 corresponds to the claims. It corresponds to a connecting pipe, the valve 14 corresponds to an on-off valve described in the claims, and the controller 15 corresponds to a control unit described in the claims.

  The heater 11 is provided on the entire circumference of the outer peripheral portion of the heat exchanger 4, and the cross-sectional shape is an annular shape surrounding the heat exchanger 4. The heater 11 has a heat storage material 11a that generates heat by a chemical reaction with a reaction medium (ammonia), and the heat storage material 11a is housed in a casing. Here, ammonia is used as the reaction medium. In the heater 11, when ammonia is supplied, the ammonia and the heat storage material 11a chemically react (chemical adsorption or coordination bond) to generate heat. Further, in the heater 11, when the heat storage material 11a is heated to a predetermined temperature or more by receiving exhaust heat of the exhaust gas, the heat storage material 11a and ammonia are separated (desorbed), and ammonia is released, making it possible to recover the ammonia. . This predetermined temperature is determined by the combination of the heat storage material 11a used in the heater 11 and the reaction medium.

The heat storage material 11 a is disposed so as to be in contact with the entire circumference of the outer peripheral surface of the outer cylinder of the heat exchanger 4. As the heat storage material 11 a, a material that generates heat by chemically reacting with ammonia as a reaction medium and can raise the exhaust gas passing through the heat exchanger 4 to the activation temperature of the catalyst (DOC5 or the like) is used. When the heat storage material 11a after reacting with ammonia stores heat from the high-temperature exhaust gas flowing through the heat exchanger 4, it desorbs ammonia. The material of the heat storage material 11a is a material having _a composition of _a halogen compound MXa, and M = alkaline earth metal such as Mg, Ca, Sr, Cr, Mn, Fe, Co, Ni, Cu, Zn, etc. Transition metal, X is Cl, Br, I, etc., a = 2,3. In addition, you may mix the additive which improves thermal conductivity with the thermal storage material 11a. Examples of the additive include carbon fibers, carbon beads, SiC beads, metal beads such as Cu, Ag, Ni, Ci—Cr, Al, Fe, and stainless steel, polymer beads, and polymer fibers. The casing is disposed so as to cover the entire outer peripheral surface of the heater 11 and the entire upstream end and downstream end of the heater 11, and a sealed space between the outer peripheral surface of the outer cylinder of the heat exchanger 4. The heat storage material 11a is enclosed therein. Thus, since the heat storage material 11a is enclosed in the sealed space, it can repeatedly react with ammonia. In addition, you may provide a heat insulating material between the thermal storage material 11a and a casing, and you may provide the heat conductive sheet formed with metal sheets, such as a graphite sheet and aluminum.

  With reference to FIG. 2, the relationship between the ammonia supply amount, generated heat amount, and rising temperature in the heater 11 will be described. FIG. 2 is a graph showing the relationship between the amount of ammonia supplied to the heater 11 and the amount of heat generated. The horizontal axis represents the amount of ammonia supplied to the heater 11, and the vertical axis represents the amount of heat generated by the heater 11. When ammonia is supplied from the storage 12 to the heater 11, the heat storage material 11a in an amount corresponding to the supply amount of ammonia chemically reacts with ammonia to generate heat. Therefore, as shown in FIG. 2, when the amount of ammonia supplied to the heater 11 increases, the amount of heat generated in the heater 11 increases linearly. Therefore, with reference to this linear graph A, the amount of generated heat can be obtained from the amount of ammonia supplied to the heater 11. In the heater 11, the temperature rises as the amount of generated heat increases. The temperature rising by the heater 11 corresponding to the amount of generated heat can be obtained by a predetermined conversion formula. This predetermined conversion formula is obtained based on the heat capacity of the heater 11 and the like.

  The storage 12 contains an adsorbent 12a that can hold (adsorb) and separate (release) ammonia as a reaction medium. As the adsorbent 12a, for example, activated carbon capable of storing ammonia by physical adsorption is used. In the storage 12, ammonia is separated from the adsorbent 12 a and supplied to the heater 11, and after the warm-up is completed, the exhaust heat of exhaust gas is received and the ammonia desorbed from the heat storage material 11 a is physically adsorbed to the adsorbent 12 a. Collect again. The adsorbent 12a is not limited to activated carbon, and for example, mesoporous material having mesopores such as mesoporous silica, mesoporous carbon and mesoporous alumina, or zeolite and silica gel may be used.

  With reference to FIG. 3, the relationship among the temperature, pressure, and ammonia adsorption amount (amount of ammonia stored in the storage 12) in the storage 12 will be described. FIG. 3A is a graph showing the relationship between the temperature in the storage 12 and the ammonia saturated vapor pressure, where the horizontal axis is temperature (° C.) and the vertical axis is ammonia saturated vapor pressure (kPa). FIG. 3B is a graph showing the relationship between the relative pressure in the storage 12 (= pressure in the storage 12 / ammonia saturated vapor pressure) −ammonia adsorption amount, the horizontal axis is relative pressure, and the vertical axis is ammonia. Adsorption amount (g).

  As shown in FIG. 3A, the temperature in the storage 12 and the ammonia saturated vapor pressure have a relationship indicated by an ammonia saturated vapor pressure curve C1 in which the ammonia saturated vapor pressure increases as the temperature increases. Therefore, the ammonia saturated vapor pressure in the storage 12 can be obtained from the temperature in the storage 12 with reference to the ammonia saturated vapor pressure curve C1. Further, as shown in FIG. 3B, the relative pressure in the storage 12 and the ammonia adsorption amount are represented by an ammonia adsorption amount curve C2 in which the ammonia adsorption amount (ammonia storage amount) increases as the relative pressure increases. There is. Therefore, the ammonia adsorption amount in the storage 12 can be obtained from the relative pressure with reference to the ammonia adsorption amount curve C2. If the temperature and pressure in the storage 12 can be obtained from these two relationships, the ammonia saturated vapor pressure is obtained from the temperature in the storage 12, the relative pressure is calculated from the ammonia saturated vapor pressure and the pressure in the storage 12, and this The ammonia adsorption amount can be determined from the relative pressure.

  In this way, the ammonia adsorption amount (ammonia storage amount) stored in the storage 12 can be estimated from the temperature and pressure in the storage 12. At the time of warm-up, the amount of ammonia obtained by subtracting the remaining amount remaining in the storage 12 in order to keep the pressure of the storage 12 and the heater 11 at a predetermined pressure from the amount of ammonia stored in the storage 12 at the time of warm-up. Can be supplied. Therefore, the amount of ammonia that can be supplied to the heater 11 can be obtained from the amount of ammonia stored in the storage 12.

  The connection pipe 13 is a pipe that connects the heater 11 and the storage 12, and serves as a flow path through which a reaction medium (ammonia) flows between the heater 11 and the storage 12. The valve 14 is disposed in the middle of the connection pipe 13 and opens and closes the ammonia flow path between the heater 11 and the storage 12. When the valve 14 is opened, ammonia can be transferred between the heater 11 and the storage 12 via the connecting pipe 13. The controller 15 performs opening / closing control of the valve 14. The valve 14 is an electromagnetic normally closed valve and opens when a current is passed. The valve 14 may be a non-electromagnetic valve.

With reference to FIG. 4, the movement of ammonia between the heater 11 and the storage 12 by the connecting pipe 13 and the valve 14 (particularly during warm-up) will be described. FIG. 4 is a conceptual diagram showing an operation after the valve is opened when the chemical heat storage device 10 is warmed up. Incidentally, in FIG. 4, NH ₃ present in the heat storage material 11a of the heater 11 shows the ammonia chemically adsorbed to the heat storage material 11a, NH ₃ present in the adsorbent in the 12a of the storage 12 to the adsorbent 12a It shows physisorbed ammonia.

Ammonia A ₁₁ in the heater 11 shown in FIG. 2 shows the ammonia gas phase in the heat storage material 11a is not chemically adsorbed. This is, for example, ammonia desorbed from the heat storage material 11a as the temperature of the heat storage material 11a increases, or residual ammonia remaining without being recovered in the storage 12. Depending on the amount of the ammonia A _11, it varies the pressure in the heater 11. In addition to the ammonia physically adsorbed on the adsorbent 12a, ammonia A ₁₂ (gas) not adsorbed on the adsorbent 12a exists in the storage 12. Depending on the amount of adsorbent 12a ammonia A ₁₂ that are not ammonia and adsorption adsorbed to vary the pressure in the storage 12.

  Before the heating object is warmed up, ammonia is stored in the storage 12, so the pressure in the storage 12 is higher than the pressure in the heater 11. When the valve 14 is controlled to open in this state, when the moving system is in a normal state, the valve 14 provided in the connection pipe 13 is opened, and the pressure difference between the storage 12 and the heater 11 causes a difference as shown in FIG. Ammonia (gas) moves from the storage 12 to the heater 11 via the connection pipe 13. In the heater 11, the heat storage material 11a and ammonia chemically react to generate heat, and the temperature rises according to the amount of generated heat. When the valve 14 is opened at the time of warming up or the like, the pressure is balanced between the heater 11 and the storage 12 connected by the connecting pipe 13 after a short time, and the pressure in the heater 11 and the pressure in the storage 12 are balanced. Becomes the same pressure (equilibrium adsorption pressure). The time until this equilibrium state is reached varies depending on the diffusion rate of ammonia, the length of the connecting pipe 13, the pipe diameter, and the like.

  However, if an abnormality occurs in the ammonia moving system including the connection pipe 13 and the valve 14, the movement of ammonia between the heater 11 and the storage 12 via the connection pipe 13 is not performed in the same manner as in a normal state. There is a case. In this case, the ammonia stored in the storage 12 does not move to the heater 11 even if a predetermined time has elapsed after the opening control of the valve 14 is started. Therefore, in the heater 11, a chemical reaction between the heat storage material 11a and ammonia is not performed, and heat is not generated. As a result, the temperature of the heater 11 does not rise, and the temperature of the object to be heated and the exhaust gas does not rise. As an abnormality in the ammonia moving system, for example, when the valve 14 is not opened due to mechanical failure or electrical failure due to aging or the like, or when a part of the heat storage material 11a is missing is clogged in the connection pipe 13, There is a case where a part of the connecting pipe 13 is damaged.

  Even if there is no abnormality in the ammonia transfer system, if the heater 11 is abnormal, the reactivity of the chemical reaction in the heater 11 may be reduced. In this case, even if the amount of ammonia that can be supplied moves to the heater 11, the heater 11 does not perform a chemical reaction between the heat storage material 11a and ammonia and generates less heat than when the reactivity is normal. As a result, the temperature rise in the heater 11 is small, and the temperature rise of the object to be heated and the exhaust gas is also small. In some cases, no chemical reaction takes place and the temperature does not rise. Examples of the abnormality of the heater 11 include a case where ammonia leaks due to the heater 11 being damaged, and a case where the heat storage material 11a in the heater 11 is deteriorated.

  The controller 15 includes a CPU [Central Processing Unit], a ROM [Read Only Memory], a RAM [Random Access Memory], and the like, and is a control unit that controls the chemical heat storage device 10. Various sensors such as temperature sensors 16, 17, 18 and a pressure sensor 19 are connected to the controller 15, and information necessary for control is appropriately acquired from the plurality of sensors. Further, the controller 15 is connected to the valve 14, performs each process for controlling the chemical heat storage device 10 based on the acquired information, and performs opening / closing control of the valve 14 as necessary. Before describing specific processing in the controller 15, the temperature sensors 16, 17, 18, and the pressure sensor 19 will be described. The controller 15 may be dedicated to the chemical heat storage device 10 or may be incorporated as a function of an ECU such as an engine ECU [Electronic Control Unit].

  In this embodiment, the temperature sensor 16 corresponds to the upstream temperature detection unit described in the claims, and the temperature sensor 17 corresponds to the downstream temperature detection unit described in the claims. Is equivalent to the acquisition unit described in the claims, the temperature sensor 18 is equivalent to the reservoir temperature detection unit described in the claims, and the pressure sensor 19 is the reservoir pressure described in the claims. It corresponds to a detection unit, and the processing in the controller 15 corresponds to an estimation unit described in the claims.

  The temperature sensor 16 is a sensor that detects the temperature of exhaust gas flowing in the exhaust pipe 3 between the engine 2 and the heat exchanger 4. The temperature sensor 16 detects the temperature of the exhaust gas upstream of the heat exchanger 4 and the heater 11 at regular intervals, and transmits the detected temperature information to the controller 15. The temperature sensor 17 is a sensor that detects the temperature of the exhaust gas flowing in the exhaust pipe 3 between the heat exchanger 4 and the DOC 5. The temperature sensor 17 detects the temperature of the exhaust gas on the downstream side of the heat exchanger 4 and the heater 11 at regular intervals, and transmits the detected temperature information to the controller 15. The temperature of the exhaust gas detected by the temperature sensors 16 and 17 is used in the following processing of the controller 15 in order to acquire the rising temperature in the heater 11 and the like.

  Note that the volume of the heat storage material 11a provided in the heater 11 expands due to a chemical reaction with ammonia. Therefore, for example, when a temperature sensor is provided inside the heater 11, it is necessary to prevent the temperature sensor from being damaged by receiving pressure due to expansion of the heat storage material 11a. The heater 11 forms a sealed space so that the heat storage material 11a enclosed in the casing can repeatedly react with ammonia. Therefore, when a temperature sensor is provided inside the heater 11, it is necessary to sufficiently ensure the airtightness of the sealed space. When it is difficult to provide a temperature sensor in the heater 11 in terms of cost, increase in the number of parts, and the like, instead of providing a temperature sensor in the heater 11 in order to obtain the temperature of the heater 11, a heat sensor is provided. Temperature sensors 16 and 17 that detect the temperature of the exhaust gas upstream and downstream of the exchanger 4 (heater 11) are used instead.

  Further, in the engine 2, the temperature of the exhaust gas necessary for combustion control is acquired by at least one of the temperature sensors 16 and 17. That is, at least one of the temperature sensors 16 and 17 that detect the temperature of the exhaust gas is an essential sensor. Therefore, by using these temperature sensors 16 and 17 also for controlling the chemical heat storage device 10, it is not necessary to separately provide a temperature sensor for acquiring the temperature of the heater 11, and an increase in cost and the number of parts can be suppressed. Can do.

  The temperature sensor 18 is a sensor that detects the temperature in the storage 12. The temperature sensor 18 detects the temperature in the storage 12 at regular time intervals, and transmits the detected temperature information to the controller 15. The pressure sensor 19 is a sensor that detects the pressure in the storage 12. The pressure sensor 19 detects the pressure in the storage 12 at regular intervals, and transmits the detected pressure information to the controller 15.

  The temperature sensors 16, 17, 18 and the pressure sensor 19 have detection response performance (response speed, etc.), respectively. Therefore, each of the temperature sensors 16, 17, and 18 takes time until the temperature after the change in the exhaust pipe 3 or the storage 12 is detected according to the response speed. Further, the pressure sensor 19 takes time until the pressure after the change is detected after the pressure in the storage 12 changes according to the response speed.

  Now, specific processing in the controller 15 will be described. The controller 15 determines whether the temperature of the exhaust gas upstream of the heat exchanger 4 detected by the temperature sensor 16 during operation of the engine 2 is equal to or lower than the warm-up start temperature. When the controller 15 determines that the temperature of the exhaust gas is equal to or lower than the warm-up start temperature, it supplies current to the valve 14 to open the valve 14. The warm-up start temperature is a temperature that requires warm-up in the exhaust gas purification system 1. The warm-up start temperature is set based on the activation temperature of the catalyst (such as DOC5).

  After completion of warm-up while the engine 2 is operating, the controller 15 determines whether or not the temperature of the exhaust gas detected by the temperature sensor 16 (corresponding to the temperature of the heater 11 (heat storage material 11a)) is higher than the ammonia recoverable temperature. judge. When the controller 15 determines that the temperature of the exhaust gas is higher than the temperature at which ammonia can be recovered, current is supplied to the valve 14 to open the valve 14. When the controller 15 determines that the temperature of the exhaust gas is equal to or lower than the temperature at which ammonia can be recovered, the controller 15 stops supplying current to the valve 14 in order to close the valve 14. The ammonia recoverable temperature is a temperature at which ammonia can be recovered from the heater 11 after warming up. The ammonia recoverable temperature is set based on the temperature at which ammonia is separated from the heat storage material 11a determined by the combination of the heat storage material 11a used in the heater 11 and ammonia. Further, the ammonia recoverable temperature may be set in consideration of the outside air temperature. For example, the higher the outside air temperature, the higher the temperature.

  In particular, at the time of warm-up, the controller 15 uses the temperature in the storage 12 detected by the temperature sensor 18 before the supply of current to the valve 14 (that is, the opening control of the valve 14), and FIG. The ammonia saturated vapor pressure curve C1 shown in FIG. The controller 15 calculates the relative pressure by dividing the pressure in the storage 12 detected by the pressure sensor 19 before the opening control of the valve 14 by the ammonia saturated vapor pressure. The controller 15 uses this relative pressure to acquire the ammonia adsorption amount in the storage 12 with reference to the ammonia adsorption amount curve C2 shown in FIG. The controller 15 subtracts the remaining amount in order to keep the pressure of the storage 12 and the heater 11 at a predetermined pressure from this ammonia adsorption amount (ammonia storage amount), so that the heater 11 before opening control of the valve 14 is subtracted. Obtain the amount of ammonia that can be supplied. Further, the controller 15 assumes that all of the supplyable amount of ammonia has been supplied to the heater 11 and uses this supplied amount of ammonia to refer to the graph (map) A shown in FIG. The amount of heat generated at 11 is acquired. Then, the controller 15 converts the generated heat amount by a predetermined conversion formula, and estimates the temperature rising by the heater 11. Note that the process for estimating the temperature rising by the heater 11 may be performed at any timing before or after the valve 14 is opened, but this estimation process is performed on the heater 11 before the valve 14 is opened. Since the amount of ammonia that can be supplied is required, at least the temperature in the storage 12 detected by the temperature sensor 18 and the pressure in the storage 12 detected by the pressure sensor 19 are acquired before the valve 14 is opened. There is a need.

  The controller 15 measures the time from the start of opening control of the valve 14 during warm-up, and determines whether or not the measured time has elapsed for a certain time. The certain time is a time required for performing a stable abnormality determination using the temperature rise in the heater 11 during warm-up. This fixed time is the longest of the time from when the valve 14 is opened until the pressure reaches an equilibrium state, the detection delay time according to the response speed of the temperature sensors 16, 17, 18 and the pressure sensor 19. Set based on long time. The fixed time is, for example, several seconds.

  When a certain period of time has elapsed after starting the opening control of the valve 14, the controller 15 changes the temperature on the upstream side of the heater 11 detected by the temperature sensor 16 from the temperature on the downstream side of the heater 11 detected by the temperature sensor 17. Subtract the temperature difference. This temperature difference is substituted as the temperature actually increased by the heater 11 during warm-up. The temperature difference may be converted using a predetermined conversion formula so that the temperature increased by the heater 11 may be obtained with higher accuracy.

  Then, in the controller 15, the temperature difference (absolutely) between the temperature measured by the heater 11 measured after the valve 14 is opened and the temperature raised by the heater 11 estimated from the amount of ammonia that can be supplied before the valve 14 is opened. Value). The controller 15 determines whether this temperature difference (absolute value) is less than a threshold value. This threshold value is a threshold value for determining whether the actually measured value and the estimated value of the rising temperature at the heater 11 are substantially the same temperature. The threshold value may be set based on detection errors of the temperature sensors 16, 17, 18 and the pressure sensor 19. Further, since the temperature of the exhaust gas is detected by the temperature sensors 16 and 17 as a substitute for the temperature of the heater 11, the temperature of the exhaust gas at the location where the temperature sensors 16 and 17 are provided and the location away from the location. The threshold value may be set in consideration of a temperature difference from the temperature of a certain heater 11.

  When the temperature difference (absolute value) is less than the threshold value, the controller 15 determines that the ammonia moving system including the connecting pipe 13 and the valve 14 and the heater 11 are normal. On the other hand, if the temperature difference (absolute value) is equal to or greater than the threshold, the controller 15 determines that there is some abnormality in the ammonia moving system or the heater 11, and notifies the vehicle driver of the abnormality. This abnormality notification includes, for example, lighting of a warning lamp of the chemical heat storage device 10, display of information indicating an abnormality of the chemical heat storage device 10 (particularly, the connection pipe 13, the valve 14, and the heater 11) and output of sound. .

  The operation of the chemical heat storage device 10 configured as described above will be described. In particular, the abnormality detection operation during warm-up will be described with reference to the flowchart of FIG. FIG. 5 is a flowchart showing an abnormality detection operation during warm-up in the chemical heat storage device 10.

  While the engine 2 is operating, the controller 15 determines whether or not the temperature of the exhaust gas detected by the temperature sensor 16 is equal to or lower than the warm-up start temperature (S1). If it is determined in S1 that the temperature of the exhaust gas is higher than the warm-up start temperature, the controller 15 stops the supply of current to the valve 14 (S2). The valve 14 is closed because no current is supplied. In this case, ammonia cannot move through the connecting pipe 13. The determination of S1 is repeatedly performed until the temperature of the exhaust gas detected by the temperature sensor 16 becomes equal to or lower than the warm-up start temperature.

  When it is determined in S 1 that the temperature of the exhaust gas is equal to or lower than the warm-up start temperature, the controller 15 calculates the storage 12 from the temperature in the storage 12 detected by the temperature sensor 18 and the pressure in the storage 12 detected by the pressure sensor 19. To obtain the amount of ammonia that can be supplied to the heater 11 by subtracting the remaining amount in order to keep the pressure of the storage 12 and the heater 11 at a predetermined pressure. The amount of heat generated in the heater 11 is acquired from the amount of ammonia that can be supplied with reference to the graph A shown in FIG. 2, and the temperature (estimated value) rising in the heater 11 is calculated from the amount of generated heat using a predetermined conversion formula ( S3). Here, assuming that the amount of ammonia that can be supplied to the heater 11 from the storage 12 before opening the valve 14 can be supplied to the heater 11, the temperature rising by the heater 11 is estimated. Then, the controller 15 supplies a current to the valve 14 (S4). When there is no abnormality in the connecting pipe 13 and the valve 14, the valve 14 opens when the supplied current flows. As a result, ammonia can be moved through the connecting pipe 13. At this time, the pressure in the storage 12 is higher than the pressure in the heater 11, and ammonia moves to the heater 11 side and flows in the connection pipe 13. Then, ammonia flowing in the connection pipe 13 is supplied to the heater 11. At this time, the pressure in the heater 11 and the pressure in the storage 12 become the same pressure in a short time after opening the valve 14 (pressure equilibrium state). When there is no abnormality in the heater 11, in the heater 11, the supplied amount of ammonia and the heat storage material 11a chemically react to generate heat, and the temperature rises according to the generated heat amount. When the heater 11 is warmed, this heat is transferred to the outer cylinder of the heat exchanger 4 and is transferred to the inside of the heat exchanger 4 due to the heat transfer effect. The entire heat exchanger 4 is heated, and the exhaust gas flowing inside the heat exchanger 4 is quickly heated. Further, the heated exhaust gas flows downstream, and the temperature of each catalyst of DOC5, SCR7, and ASC8 rises. And when the temperature of each catalyst becomes more than the activation temperature, the exhaust gas can be purified.

  The controller 15 measures the time from the start of the opening control of the valve 14 in S4, and determines whether or not a certain time has elapsed from the start (S5). The determination in S5 is repeated until a certain time has elapsed. If it is determined in S5 that the predetermined time has elapsed, the controller 15 increases the temperature at the heater 11 from the temperature at the upstream side of the heater 11 detected by the temperature sensor 16 and the temperature at the downstream side of the heater 11 detected by the temperature sensor 17. A temperature (actually measured value) is acquired (S6). Here, the temperature actually increased by the heater 11 is acquired. However, when ammonia is not supplied to the heater 11 or when the reactivity of the heater 11 is lowered, the temperature of the heater 11 is not increased.

  Then, the controller 15 calculates a difference (absolute value) between the actually measured value and the estimated value of the rising temperature at the heater 11, and determines whether or not the difference is less than the threshold value (S7). When it is determined in S7 that the difference is less than the threshold value (the temperature actually increased by the heater 11 after a certain time has elapsed from the start of the opening control of the valve 14 and the temperature increased by the heater 11 estimated from the amount of ammonia that can be supplied). In the case of substantially the same), the controller 15 determines that there is no abnormality in the ammonia moving system and the heater 11. On the other hand, if it is determined in S7 that the difference is equal to or greater than the threshold value (the temperature actually increased by the heater 11 after a certain time has elapsed from the start of the valve 14 opening control and the temperature increased by the heater 11 estimated from the amount of ammonia that can be supplied) The controller 15 detects that there is an abnormality in the ammonia moving system or the heater 11 (S8), and notifies the vehicle driver that there is an abnormality (S9). In this case, the ammonia separated from the adsorbent 12a in the storage 12 has not moved normally to the heater 11, and any one of the connecting pipe 13, the valve 14, and the heater 11 is abnormal.

  In particular, when warming up when the engine 2 is started, the temperature of the exhaust gas is low and the temperature of the heater 11 is also low before the engine 2 is started. In addition, a sufficient amount of ammonia is stored in the storage 12 before the engine 2 is started, so that a large amount of ammonia can be supplied to the heater 11 and the amount of heat generated by the heater 11 also increases. Therefore, when the engine 2 is started, the temperature rising by the heater 11 becomes large, and the determination using the temperature rising by the heater 11 can be performed with high accuracy.

  When the operation of the engine 2 is continued to some extent after the warm-up is finished and the temperature of the exhaust gas discharged from the engine 2 becomes high, ammonia and the heat storage material 11a are separated in the heater 11 and ammonia is generated. When the temperature of the exhaust gas is higher than the temperature at which ammonia can be recovered, a current is supplied to the valve 14. The valve 14 opens when the supplied current flows. As a result, ammonia can be moved in the connecting pipe 13. At this time, the pressure in the heater 11 is higher than the pressure in the storage 12, and ammonia moves to the storage 12 side and flows in the connection pipe 13. Then, the ammonia flowing through the connection pipe 13 is collected by the storage 12. In the storage 12, ammonia is adsorbed by the adsorbent 12a and stored.

  According to the chemical heat storage device 10, when the valve 14 is controlled to open during warm-up, the generated heat amount is estimated from the actual rising temperature corresponding to the generated heat amount of the heater 11 and the amount of ammonia that can be supplied. By determining that there is an abnormality when the difference from the raised temperature is greater than or equal to the threshold value, it is possible to detect an abnormality in the ammonia moving system or the heater 11 at an early stage. In particular, if this determination is performed when the engine 2 is started, the determination can be made with high accuracy.

  According to the chemical heat storage device 10, by using the temperature sensors 16 and 17 that detect the temperatures of the exhaust gas upstream and downstream of the heater 11, the heater 11 is not provided with a separate temperature sensor. The actual temperature rise at can be obtained with high accuracy. Moreover, according to the chemical heat storage device 10, the storage amount of ammonia stored in the storage 12 can be easily obtained from the temperature and pressure of the storage 12. Furthermore, according to the chemical heat storage device 10, the amount of ammonia that can be supplied to the heater 11 can be acquired by using this ammonia storage amount, and the amount of heat generated or increased by the heater 11 can be easily calculated from the amount of ammonia that can be supplied. The temperature can be estimated.

  As mentioned above, although embodiment of this invention was described, it is implemented in various forms, without being limited to the said embodiment.

  For example, in the above embodiment, the present invention is applied to an exhaust gas purification system including DOC, SCR, and ASC as a catalyst and DPF as a filter. However, the present invention may be applied to an exhaust gas purification system having other configurations, for example, DOC, SCR, ASC. The present invention may be applied to an exhaust gas purification system that does not include any one or two of these catalysts, or an exhaust gas purification system that includes a catalyst other than DOC, SCR, and ASC. Although the vehicle is a diesel engine vehicle, it can also be applied to a gasoline engine vehicle. Further, the present invention can also be applied to other mounted objects such as ships and generators using an engine as a drive source.

  Moreover, in the said embodiment, although it was set as the heat exchanger of the upstream of DOC as a heating target object, other things may be sufficient as a heating target object, for example, any catalyst of DOC, SCR, and ASC is heated. It is good also as a thing.

  Moreover, in the said embodiment, although it was set as the structure which provides a heater in the perimeter of the outer peripheral part of a heat exchanger, you may provide a heater only in a part of outer peripheral part of a heating target object, and the outer peripheral part of a heating target object For example, in order to heat exhaust gas, a heater may be provided inside the exhaust gas pipe. When a heater is provided in the exhaust gas pipe, a configuration in which a plurality of heaters and heat exchange units are alternately stacked may be employed.

  In the above embodiment, the reaction medium is ammonia, but other reaction medium such as alcohol or water may be used. In the above embodiment, each material of the heat storage material and the adsorbent when the reaction medium is ammonia is exemplified, but depending on the reaction medium used in the chemical heat storage device, other materials may be used as appropriate for the heat storage material and the adsorbent. Used.

  Moreover, in the said embodiment, in order to acquire the temperature which rises with a heater, the temperature sensor which detects the temperature of exhaust gas is between a heat exchanger and an engine (upstream side of a heater), and between a heat exchanger and DOC ( Although provided on the downstream side of the heater, the temperature sensor may be provided only between the heat exchanger and the DOC. When only the temperature of the exhaust gas downstream of the heater is used, the temperature of the exhaust gas downstream of the heater before valve opening control is subtracted from the temperature of the exhaust gas downstream of the heater after valve opening control. Get the temperature rising at. In this case, the temperature sensor on the upstream side of the heater can be reduced, and the configuration can be simplified. If the heater can be provided with a temperature sensor, the heater may be provided with a temperature sensor to directly detect the temperature in the heater. When the temperature in the heater is used, the temperature in the heater before the valve opening control is subtracted from the temperature in the heater after the valve opening control to obtain the temperature rising by the heater.

  In the above embodiment, the abnormality is determined after a lapse of a certain time from the start of the valve opening control. However, the abnormality may be determined without waiting for a certain time after the valve opening control is started. Good. When it is not necessary to wait for a certain period of time, the delay time of detection of the temperature sensor or pressure sensor or the time from when the valve is opened until the pressure is in an equilibrium state is very short, and it is not necessary to consider those times It is.

  In the above embodiment, the absolute value of the difference between the actually measured value and the estimated value of the rising temperature of the heater is calculated, and it is determined whether the absolute value of the difference is equal to or greater than (less than) the threshold value. You may judge without using. For example, in the case of warm-up, if the ammonia moving system is abnormal, the heater will not raise the temperature (the measured value of the heater's rising temperature is approximately 0), so the measured value is subtracted from the estimated value of the heater's rising temperature. A difference is acquired, and it is determined whether the difference is equal to or greater than a threshold value.

  In the above-described embodiment, the abnormality determination process is performed using the rising temperature of the heater that rises according to the amount of heat generated by the heater. However, a heating object that rises according to the amount of heat generated by the heater (for example, heat exchange) The abnormality determination process may be performed using the rising temperature in the vessel, or the abnormality determination process may be performed using the rising temperature of the exhaust gas (fluid) flowing inside the heating object that rises according to the amount of heat generated by the heater. Alternatively, the abnormality determination process may be performed using the amount of heat generated by the heater itself.

  DESCRIPTION OF SYMBOLS 1 ... Exhaust gas purification system, 2 ... Engine, 3 ... Exhaust pipe, 4 ... Heat exchanger, 5 ... Diesel oxidation catalyst (DOC), 6 ... Diesel exhaust particulate filter (DPF), 7 ... Selective reduction catalyst (SCR) 7a ... injector, 8 ... ammonia slip catalyst (ASC), 10 ... chemical heat storage device, 11 ... heater, 12 ... storage, 13 ... connecting pipe, 14 ... valve, 15 ... controller, 16, 17, 18 ... temperature sensor, 19 ... Pressure sensor.

Claims (7)

A chemical heat storage device for heating an object to be heated,
A heat storage material that chemically reacts with the reaction medium to generate heat, and a heater that heats the heating object;
A reservoir for storing the reaction medium;
A connecting pipe that connects the heater and the reservoir and through which a reaction medium flows;
An on-off valve provided in the connection pipe;
A controller for controlling opening and closing of the on-off valve;
An acquisition unit that acquires a value related to the amount of heat generated by the heater at the time of heating the heating object;
An estimation unit that estimates a value related to the amount of heat generated by the heater from the amount of reaction medium that can be supplied from the reservoir to the heater;
With
When the control unit performs open control of the on-off valve to supply the reaction medium from the reservoir to the heater, the control unit estimates the value related to the generated heat amount acquired by the acquisition unit and the estimation unit. A chemical heat storage device that performs a determination process for determining an abnormality when a difference from a value related to the amount of generated heat is equal to or greater than a threshold value.   The value relating to the amount of generated heat includes the rising temperature of the heater that rises according to the amount of generated heat, the rising temperature of the object to be heated that rises according to the amount of generated heat, and the heating subject that rises according to the amount of generated heat. The chemical heat storage device according to claim 1, wherein the chemical heat storage device has any one of the rising temperatures of the fluid flowing in the interior of the fluid. The chemical heat storage device is mounted on a vehicle having an engine as a driving source, heats a heating object in an exhaust system of the vehicle,
A downstream temperature detector for detecting the temperature of the exhaust gas downstream of the heater;
The chemical heat storage device according to claim 2, wherein the acquisition unit acquires the increased temperature from the temperature of the downstream exhaust gas detected by the downstream temperature detection unit. An upstream temperature detector for detecting the temperature of the exhaust gas upstream of the heater;
The acquisition unit acquires the increased temperature from a temperature difference obtained by subtracting the temperature of the upstream exhaust gas detected by the upstream temperature detection unit from the temperature of the downstream exhaust gas detected by the downstream temperature detection unit. The chemical heat storage device according to claim 3.   5. The chemical heat storage device according to claim 3, wherein the control unit performs the determination process when opening control of the on-off valve is performed when the engine is started. 6.   The estimation unit acquires a storage amount of the reaction medium stored in the reservoir, acquires an amount of the reaction medium that can be supplied to the heater from the storage amount of the reaction medium, and The chemical heat storage device according to any one of claims 1 to 5, wherein a value related to the amount of heat generated by the heater is estimated from the amount. A reservoir temperature detector for detecting the temperature of the reservoir;
A reservoir pressure detector for detecting the pressure of the reservoir;
With
The chemical heat storage device according to claim 6, wherein the estimation unit acquires the storage amount of the reaction medium using the temperature detected by the reservoir temperature detection unit and the pressure detected by the reservoir pressure detection unit.

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