WO2015174243A1

WO2015174243A1 - Chemical heat storage device

Info

Publication number: WO2015174243A1
Application number: PCT/JP2015/062409
Authority: WO
Inventors: 康佐竹; 野口　幸宏
Original assignee: 株式会社豊田自動織機
Priority date: 2014-05-13
Filing date: 2015-04-23
Publication date: 2015-11-19
Also published as: JP2017120130A

Abstract

　A chemical heat storage device (10) that is mounted on a mounting object in which an engine (2) is a power source, said heat storage device (10) heating a heating object (4) in the mounting object, wherein the chemical heat storage device (10) is provided with: a heater (11) for heating the heating object (4), the heater (11) having a heat storage material (11a) that chemically reacts with a reaction medium to generate heat; a reservoir (12) for storing the reaction medium; a connection tube (13) for connecting the heater (11) and the reservoir (12), and channeling the reaction medium; an open/close valve (14) provided to the connection tube (13); a control unit (15) for controlling the opening/closing of the open/close valve; and a temperature acquisition unit (16) for acquiring the temperature of the heater (11). When the engine (2) stops, the control unit (15) keeps the open/close valve (14) in an open state until the temperature of the heater (11) acquired by the temperature acquisition unit (16) falls to or below a threshold value.

Description

Chemical heat storage device

The present invention relates to a chemical heat storage device.

In an exhaust system of a vehicle or the like, a catalyst or the like is provided to purify environmental pollutants (HC, CO, NOx, etc.) contained in exhaust gas discharged from the engine. The catalyst has an optimum temperature (activation temperature) for activating the purification capacity. When starting the engine, the temperature of the exhaust gas is low, and it takes time to reach the activation temperature of the catalyst. Therefore, there is a case where a heating device for warming up the catalyst is provided in order to raise the temperature in a short time to the activation temperature of the catalyst when the temperature of the exhaust gas is low at the time of starting the engine. As this heating device, there is a chemical heat storage device using reaction heat of a chemical reaction between a reaction medium and a heat storage material in order to reduce energy loss (fuel consumption loss) and warm up. As a chemical heat storage device, for example, in Patent Document 1, a heat storage body storage container and a water storage container are provided, and steam is supplied between the heat storage body storage container and the water storage container by a steam supply / discharge device (pipe, valve). A chemical heat storage device is disclosed in which valves are opened and closed according to the temperature of the heat storage body stored in the heat storage body storage container and the temperature of the water stored in the water storage container.

JP 2010-169297 A

In the chemical heat storage device provided in the exhaust system, when the engine is stopped, the valve is closed so that the reaction medium stored in the storage does not move to the heater in which the heat storage material is arranged. Therefore, normally, when the engine stops, the valve is closed. However, when the temperature of the heating target portion where the heater is disposed is high when the engine is stopped, the reaction medium is separated from the heat storage material even after the engine is stopped, and the reaction medium is generated in the heater. At this time, if the reaction medium cannot move from the heater to the reservoir with the valve closed, the pressure in the heater increases and an overpressure state occurs.

Therefore, in this technical field, there is a demand for a chemical heat storage device that can avoid an overpressure state of the heater when the engine is stopped.

A chemical heat storage device according to one aspect of the present invention is a chemical heat storage device that is mounted on an object to be mounted using an engine as a drive source and heats the object to be heated in the object to be mounted, and that chemically reacts with a reaction medium. A heat storage material that generates heat, a heater that heats an object to be heated, a reservoir that stores a reaction medium, a heater and a reservoir, and a connection pipe through which the reaction medium flows, and a connection pipe An opening / closing valve provided, a control unit for controlling opening / closing of the opening / closing valve, and a temperature acquisition unit for acquiring the temperature of the heater, the control unit of the heater acquired by the temperature acquisition unit when the engine is stopped The open / close valve remains open until the temperature falls below the threshold.

The mounting object on which this chemical heat storage device is mounted has an engine as a drive source and has a heating object that requires heating. The chemical heat storage device includes a heater disposed at a location where the object to be heated can be heated and a reservoir disposed at other locations, and the heater and the reservoir are connected by a connecting pipe. An opening / closing valve is provided in the connecting pipe, and the opening / closing valve is opened when the reaction medium is supplied from the reservoir to the heater or when the reaction medium is recovered from the heater. In the chemical heat storage device, the control unit performs opening / closing control of the opening / closing valve. When heating (warm-up) of the object to be heated is required, the on-off valve is opened, so in the heater, when the reaction medium is supplied from the reservoir, the heat storage material and the reaction medium react chemically to generate heat. And heat the object to be heated. When the engine is operated and the temperature of the object to be heated increases, the heater is warmed up and the heat storage material and the reaction medium are separated. At this time, since the on-off valve is opened, the reaction medium moves from the heater to the reservoir. In the reservoir, the reaction medium is recovered and stored. In particular, in a chemical heat storage device, the temperature acquisition unit acquires the temperature of the heater (and thus the heat storage material), and when the engine stops, the opening / closing valve is opened until the acquired temperature of the heater falls below a threshold value. Maintain state. This threshold value is a temperature threshold value for determining whether or not the reaction medium is separated from the heat storage material in the heater and the reaction medium can still be recovered from the heater. Therefore, when the temperature of the heater is higher than the threshold value, the reaction medium may be separated from the heat storage material in the heater and the reaction medium may be recovered. In this case, the open state of the on-off valve is maintained, so that the reaction medium can move from the heater to the reservoir via the connecting pipe. Therefore, even if the reaction medium is separated from the heat storage material in the high-temperature heater after the engine is stopped, the reaction medium can be recovered by the reservoir, and the pressure in the heater does not increase. Thus, when the engine is stopped, the chemical heat storage device can avoid the overpressure state of the heater by maintaining the open state of the on-off valve until the temperature of the heater becomes equal to or lower than the threshold value.

In addition, as acquisition of the temperature of the heater by the temperature acquisition unit, the temperature of the heater may be directly detected, or the temperature at a location where the temperature of the heater can be estimated is detected, and the temperature of the location is detected. The temperature of the heater may be estimated and acquired, or the temperature at that point may be used as it is. The mounted object may be anything that uses an engine as a drive source and has a heated object that requires heating, such as a vehicle equipped with an engine, a ship equipped with an engine, and a generator equipped with an engine. The object to be heated varies depending on the object to be mounted. For example, in the case of a vehicle on which an engine is mounted, the object to be heated is a heat exchanger or a catalyst through which exhaust gas from the engine flows.

In the chemical heat storage device according to an embodiment, the threshold value is set at a temperature that takes into account a margin on the side lower than the temperature at which the reaction medium separates from the heat storage material.

The reaction medium is separated from the heat storage material when the temperature of the heat storage material is higher than the separation temperature determined by the combination of the heat storage material and the reaction medium. Also, the temperature of the heater (heat storage material) acquired by the temperature acquisition unit varies depending on the detection accuracy when detecting the temperature, and when estimating from the temperature detected at other locations There are variations depending on the estimation accuracy. Therefore, if the determination is performed using the separation temperature as a threshold value as it is, the determination may not be performed with high accuracy. Therefore, in order to improve the determination accuracy, the threshold value is a temperature threshold value in which a margin temperature is added to the lower side (safe side) than the above separation temperature. By setting such a threshold value, it is possible to determine with high accuracy whether or not the reaction medium can still be recovered after the engine is stopped even when the temperature of the heater acquired by the temperature acquisition unit varies. The temperature serving as the margin may be set in consideration of the variation in temperature acquired by the temperature acquisition unit as described above.

In the chemical heat storage device according to the embodiment, the temperature acquisition unit detects the temperature of the exhaust gas discharged from the engine, and acquires the temperature of the heater from the detected temperature of the exhaust gas.

It may be difficult to provide a temperature sensor that directly detects the temperature in the heater. In the engine exhaust system, the temperature of the exhaust gas is usually detected for use in engine control and the like. Therefore, the temperature acquisition unit acquires the temperature of the heater from the detected temperature of the exhaust gas by using the temperature detection of the exhaust gas. At this time, the temperature of the heater may be estimated from the temperature of the exhaust gas, or the temperature of the exhaust gas may be used as it is as the temperature of the heater.

A chemical heat storage device according to an aspect of the present invention is a chemical heat storage device that is mounted on a vehicle and heats an object to be heated in the vehicle, and has a heat storage material that chemically reacts with a reaction medium to generate heat. A heater for heating the object to be heated, a reservoir for storing the reaction medium, a connection pipe through which the reaction medium flows, the open / close valve provided in the connection pipe, and the open / close valve. A control unit that controls the opening and closing of the heater, and a temperature acquisition unit that acquires the temperature of the heater, the control unit is less than a threshold temperature of the heater acquired by the temperature acquisition unit when the vehicle drive source is stopped Keep the open / close valve open until.

The vehicle on which this chemical heat storage device is mounted has an object to be heated that requires heating. The chemical heat storage device includes a heater disposed at a location where the object to be heated can be heated and a reservoir disposed at other locations, and the heater and the reservoir are connected by a connecting pipe. An opening / closing valve is provided in the connecting pipe, and the opening / closing valve is opened when the reaction medium is supplied from the reservoir to the heater or when the reaction medium is recovered from the heater. In the chemical heat storage device, the control unit performs opening / closing control of the opening / closing valve. When heating (warm-up) of the object to be heated is required, the on-off valve is opened, so in the heater, when the reaction medium is supplied from the reservoir, the heat storage material and the reaction medium react chemically to generate heat. And heat the object to be heated. When the temperature of the object to be heated increases, the heater is warmed and the heat storage material and the reaction medium are separated. At this time, since the on-off valve is opened, the reaction medium moves from the heater to the reservoir. In the reservoir, the reaction medium is recovered and stored. In particular, in a chemical heat storage device, the temperature acquisition unit acquires the temperature of the heater (and thus the heat storage material), and when the vehicle drive source stops, the temperature of the acquired heater is opened or closed until it falls below a threshold value. Keep the valve open. This threshold value is a temperature threshold value for determining whether or not the reaction medium is separated from the heat storage material in the heater and the reaction medium can still be recovered from the heater. Therefore, when the temperature of the heater is higher than the threshold value, the reaction medium may be separated from the heat storage material in the heater and the reaction medium may be recovered. In this case, the open state of the on-off valve is maintained, so that the reaction medium can move from the heater to the reservoir via the connecting pipe. Therefore, even if the reaction medium is separated from the heat storage material in the high-temperature heater after the driving source of the vehicle is stopped, the reaction medium can be recovered by the storage and the pressure in the heater does not increase. Thus, the chemical heat storage device can avoid an overpressure state of the heater by maintaining the open state of the on-off valve until the temperature of the heater becomes equal to or lower than the threshold when the vehicle drive source is stopped.

The reaction medium is separated from the heat storage material when the temperature of the heat storage material is higher than the separation temperature determined by the combination of the heat storage material and the reaction medium. Also, the temperature of the heater (heat storage material) acquired by the temperature acquisition unit varies depending on the detection accuracy when detecting the temperature, and when estimating from the temperature detected at other locations There are variations depending on the estimation accuracy. Therefore, if the determination is performed using the separation temperature as a threshold value as it is, the determination may not be performed with high accuracy. Therefore, in order to improve the determination accuracy, the threshold value is a temperature threshold value in which a margin temperature is added to the lower side (safe side) than the above separation temperature. By setting such a threshold value, even when there is a variation in the temperature of the heater acquired by the temperature acquisition unit, it is determined with high accuracy whether or not the reaction medium can still be recovered after the vehicle drive source is stopped. it can. The temperature serving as the margin may be set in consideration of the variation in temperature acquired by the temperature acquisition unit as described above.

In the chemical heat storage device according to the embodiment, the heater is a heater that heats the heating object on the path of the exhaust gas discharged from the engine of the vehicle, and the temperature acquisition unit is the exhaust discharged from the engine. The temperature of the gas is detected, and the temperature of the heater is obtained from the detected temperature of the exhaust gas.

In the chemical heat storage device according to the embodiment, the heater is a heater that heats the heating target on the path of the vehicle heat medium, and the temperature acquisition unit determines the temperature of the heat medium heated by the heating target. And detecting the temperature of the heater from the detected temperature of the heat medium.

It may be difficult to provide a temperature sensor that directly detects the temperature in the heater. Therefore, the temperature acquisition unit acquires the temperature of the heater from the temperature of the heat medium heated by the object to be heated instead of providing a temperature sensor in the heater. At this time, the temperature of the heater may be estimated from the temperature of the heat medium, or the temperature of the heat medium may be used as it is as the temperature of the heater.

This chemical heat storage device can avoid an overpressure state of the heater when the engine is stopped.

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 flowchart which shows the operation | movement at the time of the engine stop 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.

The chemical heat storage device according to one 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 SlipataCatalyst] 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.

Referring to FIG. 1, an overall configuration of an exhaust gas purification system 1 according to an embodiment will be described. 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 (transmits) 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 7a, it 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 of the

catalysts

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 a heating target such as a catalyst without external energy. That is, the chemical heat storage device 10 stores the reaction medium separated from the heat storage material by receiving heat from the object to be heated, and supplies the stored reaction medium to the heat storage material when necessary. A chemical reaction is performed, and an object to be heated is heated by using reaction heat at the time of the chemical reaction. That is, it can be said that the chemical heat storage device 10 stores heat from the heating object and supplies it again to the heating object. 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 connection 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 periphery 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 the reaction medium, and the heat storage material 11a is housed in a casing. Here, ammonia is used as the reaction medium. In the heater 11, the supplied ammonia and the heat storage material 11a undergo a chemical reaction (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. This material is a material having a MXa composition of _a halogen compound, M = alkaline earth metals such as Mg, Ca, Sr, transition metals such as Cr, Mn, Fe, Co, Ni, Cu, Zn. X is Cl, Br, I, etc., and a = 2 and 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.

The storage 12 includes an adsorbent 12a capable of storing 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, the ammonia desorbed from the heat storage material 11a in response to exhaust heat of the exhaust gas is stored in a state of being physically adsorbed on the adsorbent 12a, and ammonia is separated from the adsorbent 12a and supplied to the heater 11. 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.

The connecting 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.

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 a temperature sensor 16 and an ignition switch 17 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 sensor 16 and the ignition switch 17 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].

The temperature sensor 16 is a sensor that detects the temperature of the 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 at regular intervals, and transmits the detected temperature information to the controller 15. The temperature of the exhaust gas detected by the temperature sensor 16 is substituted for the temperature of the heater 11 (and thus the heat storage material 11a), and is used in the processing of the controller 15 described below. The temperature of the exhaust gas detected by the temperature sensor 16 may be converted by a predetermined conversion formula to estimate the temperature of the heater 11, and the estimated temperature may be used in the processing of the controller 15 below. In this embodiment, the temperature sensor 16 corresponds to the temperature acquisition unit described in the claims.

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. A temperature sensor 16 that detects the temperature of the exhaust gas upstream of the exchanger 4 (heater 11) is used instead.

In the engine 2, the temperature of the exhaust gas necessary for combustion control is acquired by the temperature sensor 16. That is, the temperature sensor 16 that detects the temperature of the exhaust gas is an essential sensor. Therefore, by using this temperature sensor 16 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. .

The ignition switch 17 is a switch for starting / stopping the engine 2, and is a switch for the vehicle driver to select any one of OFF, accessory ON, ignition ON, and engine start modes. The ignition switch 17 transmits the selected switch information to the controller 15. When the driver performs an OFF operation using the ignition switch 17, the engine ECU stops the engine 2 in response to the ignition switch 17 being turned OFF. Therefore, it can be determined from the switch information of the ignition switch 17 whether the engine 2 has stopped.

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, the controller 15 supplies a 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 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, and the margin temperature is set to a lower side (safe side) than the reference temperature. It is set at a temperature that takes into account. That is, the ammonia recoverable temperature is set at a temperature that is lower by the margin temperature than the ammonia separation temperature determined by the combination of the heat storage material 11a and ammonia. The margin temperature for lowering the temperature is such that the temperature of the exhaust gas is detected by a temperature sensor 16 provided between the engine 2 and the heat exchanger 4 as a substitute for the temperature of the heater 11. Consider the temperature difference between the temperature of the exhaust gas at the location where the temperature sensor 16 is provided and the temperature of the heater 11 (heat storage material 11a) at a location away from this location, and the variation in the detected temperature according to the detection accuracy of the temperature sensor 16 Is set. 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 this embodiment, the ammonia recoverable temperature corresponds to the threshold value described in the claims.

Further, during the operation of the engine 2, the controller 15 determines whether or not the state of the ignition switch 17 indicated by the switch information from the ignition switch 17 is turned off (whether the engine 2 is stopped). When the controller 15 determines that the ignition switch 17 has been turned OFF, 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 ammonia recoverable temperature. When the controller 15 determines that the temperature of the exhaust gas is higher than the temperature at which ammonia can be recovered, the controller 15 continues to supply current to the valve 14 in order to maintain the valve 14 in the open state. On the other hand, when the controller 15 determines that the temperature of the exhaust gas is equal to or lower than the ammonia recoverable temperature, the controller 15 stops supplying current to the valve 14 in order to close the valve 14. Thereby, even after the engine 2 is stopped, the valve 14 can be kept open until the temperature of the exhaust gas (corresponding to the temperature of the heater 11 (heat storage material 11a)) becomes equal to or lower than the temperature at which ammonia can be recovered.

The operation of the chemical heat storage device 10 configured as described above will be described. In particular, the operation when the engine 2 is stopped will be described with reference to the flowchart of FIG. FIG. 2 is a flowchart showing the operation of the chemical heat storage device 10 when the engine is stopped.

When the engine 2 is stopped, no current is supplied to the valve 14 and the valve 14 is closed. Therefore, even if ammonia is separated from the adsorbent 12 a in the storage 12, ammonia is not supplied to the heater 11 via the connection pipe 13. The ignition switch 17 is turned on by the driver of the vehicle, and the engine 2 is started. In the controller 15, when it is determined that the temperature of the exhaust gas detected by the temperature sensor 16 is equal to or lower than the warm-up start temperature, 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 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. In the heater 11, the supplied ammonia and the heat storage material 11a chemically react to generate heat. This heat is transferred to the outer cylinder of the heat exchanger 4 and is transferred to the inside of the heat exchanger 4 by 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. When the warm-up is completed, the controller 15 stops the supply of current to the valve 14 when the temperature of the exhaust gas detected by the temperature sensor 16 is determined to be equal to or lower than the ammonia recoverable temperature. The valve 14 is closed when the supply of current is stopped. Thereby, the movement of ammonia in the connection pipe 13 becomes impossible.

When the operation of the engine 2 continues to some extent after the warm-up is completed 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 controller 15 determines that the temperature of the exhaust gas detected by the temperature sensor 16 is higher than the temperature at which ammonia can be recovered, 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.

In addition, when the controller 15 determines that the temperature of the exhaust gas detected by the temperature sensor 16 is equal to or lower than the temperature at which ammonia can be recovered, the supply of current to the valve 14 is stopped. The valve 14 is closed when the supply of current is stopped. Thereby, the movement of ammonia in the connection pipe 13 becomes impossible.

During the operation of the engine 2, when the temperature of the exhaust gas becomes equal to or lower than the warm-up start temperature, the chemical heat storage device 10 repeatedly performs the warm-up operation similar to the above, and the exhaust gas temperature becomes higher than the ammonia recoverable temperature. The same operation at the time of ammonia recovery as described above is repeated.

In particular, when the controller 15 determines that the ignition switch 17 is turned off (the engine 2 is stopped) (S1), 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 determined to be equal to or lower than the ammonia recoverable temperature (S2). This determination of S2 is repeatedly performed until the temperature of the exhaust gas detected by the temperature sensor 16 becomes equal to or lower than the temperature at which ammonia can be recovered.

While it is determined in S2 that the temperature of the exhaust gas is higher than the temperature at which ammonia can be recovered (that is, until the temperature of the exhaust gas becomes lower than the temperature at which ammonia can be recovered), the controller 15 supplies current to the valve 14. (S3). At this time, the engine 2 is stopped, but since the heater 11 (heat storage material 11a) is still in a high temperature state, ammonia and the heat storage material 11a may be separated in the heater 11 and ammonia may be generated. At this time, since the valve 14 is maintained in the open state by being supplied with current (S3), the ammonia can be moved through the connecting pipe 13. Therefore, ammonia generated in the heater 11 can move to the storage 12 side and flows in the connection pipe 13. Then, the ammonia flowing in the connection pipe 13 is collected by the storage 12, and the storage 12 can store the ammonia by adsorbing it with the adsorbent 12a. Therefore, the heater 11 does not increase the pressure.

When it is determined in S2 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 (S4). When the supply of current is stopped, the valve 14 is closed (S4), and ammonia cannot be moved through the connecting pipe 13. As a result, even when ammonia stored in the storage 12 is separated from the adsorbent 12 a while the engine 2 is stopped, ammonia is not supplied to the heater 11 via the connection pipe 13.

According to this chemical heat storage device 10, when the engine 2 is stopped, the valve 14 is kept open until the temperature of the heater 11 (the temperature of the exhaust gas detected by the temperature sensor 16) is equal to or lower than the ammonia recoverable temperature. Thus, an overpressure state of the heater 11 can be avoided. Moreover, according to the chemical heat storage device 10, the temperature of the engine 2 of the engine 2 is set by setting a temperature that takes a margin on the side (safe side) lower than the ammonia separation temperature determined by the combination of the heat storage material 11a and ammonia as the ammonia recoverable temperature. It can be determined with high accuracy whether or not ammonia can still be recovered after stopping. Further, according to the chemical heat storage device 10, it is not necessary to provide a separate temperature sensor for the heater 11 by using the temperature sensor 16 for acquiring the temperature of the heater 11.

For example, when the engine 2 is stopped from a transient state such as rapid acceleration, even after the engine 2 is stopped, the temperature of the exhaust system is high and the heater 11 is also in a high temperature state. Therefore, in the heater 11, ammonia may be separated from the heat storage material 11a and ammonia may be generated. In such a case, the chemical heat storage device 10 maintains the valve 14 in the open state until the temperature is below the temperature at which ammonia can be recovered, and the heater 11 does not enter an overpressure state.

As mentioned above, although embodiment of this invention was described, it is implemented with 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.

Further, although the reaction medium is ammonia in the above embodiment, 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.

In the above embodiment, in order to acquire the temperature of the heater, a temperature sensor that detects the temperature of the exhaust gas is provided between the heat exchanger and the engine, but the temperature sensor that detects the temperature of the exhaust gas is provided in the exhaust gas. For example, a temperature sensor may be provided between the heat exchanger and the DOC, or between the heat exchanger and the engine, and between the heat exchanger and the DOC. A temperature sensor may be provided, and the heater temperature may be acquired from the temperatures detected at the two locations. 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 (particularly the heat storage material).

In the above embodiment, the switch information from the ignition switch is received to determine whether the engine has stopped. However, if the controller and the engine ECU are separate, a signal indicating the engine stop is sent from the engine ECU. It may be configured to receive the information, or the switch information of the ignition switch may be received via the engine ECU. If the controller is incorporated as a function of the engine ECU, the engine is stopped in the engine ECU. Can be obtained.

Moreover, in the said embodiment, although it was set as the structure which takes a margin into the side (safety side) lower than the ammonia separation temperature determined from the combination of a heat storage material and a reaction medium, the temperature which can collect | recover ammonia is set, but a heater (heat storage material) Depending on conditions such that the temperature can be obtained with high accuracy, the ammonia recoverable temperature may be set without taking such a margin into consideration.

Moreover, in the said embodiment, although it mounted in the mounting target object which uses an engine as a drive source, and illustrated the chemical heat storage apparatus which heats the heating target object in the said mounting target object, the said chemical heat storage apparatus is mounted in the vehicle, It may be a chemical heat storage device for heating an object to be heated in the vehicle. That is, the chemical heat storage device is not limited to the one that warms the exhaust gas, and may be one that warms various heat media in the vehicle such as engine oil, transmission oil, cooling water, or air.

When the chemical heat storage device is applied to various heat media, a heater may be disposed on the outer periphery of the heat medium path through which the heat medium flows, and the heat medium flow path may be heated by the heater. In this case, the heat medium flow path becomes a heating object. Moreover, it is good also as a structure which arrange | positions a heat exchanger in a heat-medium flow path, and heats the said heat exchanger with a heater. In this case, the heat exchanger becomes a heating object. Furthermore, a plurality of heaters on which heat storage materials are arranged and heat exchange parts such as heat exchange fins are alternately arranged to form a heat exchange part integrated heater, and in the heat medium storage part for storing the heat medium or on the heat medium flow path It is good also as a structure which arrange | positions a heat exchanger integrated heater. In this case, the heat exchanging unit disposed adjacent to each heater is a heating target.

Moreover, in the said embodiment, based on the temperature of the exhaust gas detected by the temperature sensor which detects the temperature of exhaust gas, the temperature of the heater which heats the heat exchanger (heating target) on the path | route of exhaust gas is acquired. However, the temperature of the heater that heats the heating object on the path through which the heat medium flows may be acquired based on the temperature of the heat medium (for example, oil).

Further, in the above embodiment, in an engine vehicle equipped with an engine as a vehicle drive source, it is determined whether the vehicle drive source is stopped based on an ignition switch being turned off or an engine stop signal from the engine ECU. is doing. On the other hand, in the case of an electric vehicle or a fuel cell vehicle equipped with a motor as a vehicle drive source, the vehicle is driven based on the fact that the power switch is turned off or a motor stop signal from the PCU (control ECU). What is necessary is just to determine the stop of a source.

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, 11a ... heat storage material, 12 ... storage, 12a ... adsorbent, 13 ... connecting pipe, 14 ... valve, 15 ... controller , 16 ... Temperature sensor, 17 ... Ignition switch.

Claims

A chemical heat storage device that is mounted on a mounting object using an engine as a drive source and heats the heating object in the mounting object,
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 control unit for controlling opening and closing of the on-off valve;
A temperature acquisition unit for acquiring the temperature of the heater;
With
The said control part is a chemical heat storage apparatus which maintains the open state of the said on-off valve until the temperature of the said heater acquired in the said temperature acquisition part becomes below a threshold value when the said engine stops.
2. The chemical heat storage device according to claim 1, wherein the threshold value is set at a temperature in which a margin is added to a side lower than a temperature at which the reaction medium is separated from the heat storage material.
The chemical heat storage device according to claim 1, wherein the temperature acquisition unit detects a temperature of exhaust gas discharged from the engine and acquires a temperature of the heater from the detected temperature of the exhaust gas. .
A chemical heat storage device mounted on a vehicle for heating an object to be heated in the vehicle,
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 control unit for controlling opening and closing of the on-off valve;
A temperature acquisition unit for acquiring the temperature of the heater;
With
The said control part is a chemical thermal storage apparatus which maintains the open state of the said on-off valve until the temperature of the said heater acquired by the said temperature acquisition part becomes below a threshold value when the drive source of the said vehicle stops.
The chemical heat storage device according to claim 4, wherein the threshold value is set at a temperature with a margin added to a side lower than a temperature at which the reaction medium is separated from the heat storage material.
The heater is a heater that heats the heating object on a path of exhaust gas discharged from the engine of the vehicle,
The chemical heat storage device according to claim 4, wherein the temperature acquisition unit detects a temperature of exhaust gas discharged from the engine, and acquires the temperature of the heater from the detected temperature of the exhaust gas. .
The heater is a heater that heats the heating object on a path of a heat medium of the vehicle,
The chemistry according to claim 4 or 5, wherein the temperature acquisition unit detects the temperature of the heating medium heated by the heating object, and acquires the temperature of the heater from the detected temperature of the heating medium. Thermal storage device.