JP2019027392A - Reductant thawing device - Google Patents

Abstract

To provide a reductant thawing device capable of inhibiting components arranged near a heater from becoming overheated states when the temperature of reductant in a reductant tank is high.SOLUTION: To solve the issue, a reductant thawing device 100 which utilizes a heater 105 in thawing reductant 103 in a reductant supply pipe 104 of a selective catalyst reduction system 101, includes a heater output change part 114 for changing heater output according to the temperature of the reductant in a reductant tank 102 of the selective catalyst reduction system 101.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a reducing agent thawing device for thawing a reducing agent.

  A selective catalytic reduction (SCR) system includes a reducing agent tank that stores a reducing agent (for example, urea water), a reducing agent injector that injects the reducing agent into engine exhaust, and a reducing agent in the reducing agent tank. And a reducing agent supply pipe for supplying to the injector.

  When the reducing agent freezes, it is necessary to thaw the reducing agent in the reducing agent tank and the reducing agent in the reducing agent supply pipe. Engine cooling water is used when thawing the reducing agent in the reducing agent tank, and a heater is used when thawing the reducing agent in the reducing agent supply pipe.

  When thawing the reducing agent in the reducing agent supply pipe, the heater output is set to a high output (for example, maximum output), but after the thawing of the reducing agent in the reducing agent supply pipe is completed, it takes a long time. If the heater output is kept at a high output, there is a risk that the components arranged in the vicinity of the heater will be overheated.

  Therefore, when thawing of the reducing agent in the reducing agent supply pipe is completed, the heater output according to the outside temperature is enough to prevent re-freezing of the reducing agent in the reducing agent supply pipe that has already been thawed. Is low output.

JP, 2006-108950, A JP 2009-097348 A JP 2008-248709 A JP 2000-027627 A

  However, since the amount of reducing agent in the reducing agent tank is overwhelmingly large compared to the amount of reducing agent in the reducing agent supply pipe, if the reducing agent temperature in the reducing agent tank is high, the heater output is reduced according to the outside temperature. In terms of output, when the reducing agent in the reducing agent tank is supplied to the reducing agent injector, the reducing agent temperature in the reducing agent supply pipe suddenly rises, and there is a possibility that the components arranged in the vicinity of the heater will be overheated.

  In view of the above circumstances, the present invention is to provide a reducing agent thawing device that can prevent the parts arranged near the heater from being overheated even if the reducing agent temperature in the reducing agent tank is high. Objective.

  The present invention provides a reducing agent thawing device in which a heater is used when thawing a reducing agent in a reducing agent supply pipe of a selective catalyst reduction system, and the reducing agent temperature in the reducing agent tank of the selective catalyst reduction system is adjusted. Accordingly, a reducing agent thawing device including a heater output changing unit that changes the heater output is provided.

  When the reducing agent temperature in the reducing agent tank during thawing of the reducing agent in the reducing agent supply pipe is less than a first temperature threshold, the heater output changing unit sets the heater output as the first heater output, and reduces the reducing agent. When the reducing agent temperature in the reducing agent tank during thawing of the reducing agent in the agent supply pipe is equal to or higher than the first temperature threshold, the heater output is compared with the first heater output, It is desirable to do.

  The heater output changing unit preferably determines the first temperature threshold based on a battery voltage, a reducing agent temperature, an outside air temperature, a reducing agent remaining amount, and a reducing agent concentration.

  The heater output changing unit is configured such that the reducing agent temperature in the reducing agent tank during the retention of the reducing agent in the reducing agent supply pipe after the thawing of the reducing agent in the reducing agent supply pipe is completed is a second temperature threshold value. If less than, the heater output is set as the third heater output, and the reducing agent in the reducing agent tank is kept warm while the reducing agent in the reducing agent supply pipe is being thawed after thawing of the reducing agent in the reducing agent supply pipe is completed. When the agent temperature is equal to or higher than the second temperature threshold value, it is desirable to compare the heater output with the third heater output to obtain a low output fourth heater output.

  The heater output changing unit preferably determines the second temperature threshold based on a battery voltage, a reducing agent temperature, an outside air temperature, a reducing agent remaining amount, and a reducing agent concentration.

  According to the present invention, it is possible to provide a reducing agent thawing device that can suppress the parts placed near the heater from being overheated even when the reducing agent temperature in the reducing agent tank is high.

It is a block diagram explaining the structure of the reducing agent thaw | decompression apparatus which concerns on embodiment of this invention. It is a flowchart explaining operation | movement of the reducing agent thaw | decompression apparatus which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  As shown in FIG. 1, in the reducing agent thawing device 100 according to the embodiment of the present invention, when reducing agent (for example, urea water) 103 in the reducing agent tank 102 of the selective catalyst reduction system 101 is thawed. The engine cooling water is used, and the heater 105 is used when the reducing agent 103 in the reducing agent supply pipe 104 of the selective catalyst reduction system 101 is thawed.

  More specifically, when the reducing agent 103 in the reducing agent tank 102 is thawed, a valve (not shown) is opened through the controller 106 and engine cooling water is supplied to the reducing agent tank 102 to thereby reduce the inside of the reducing agent tank 102. An amount of heat is given to the reducing agent 103.

  Further, when the reducing agent 103 in the reducing agent supply pipe 104 is thawed, the heater 105 is driven through the controller 106 to give heat to the reducing agent 103 in the reducing agent supply pipe 104.

  The selective catalyst reduction system 101 includes a reducing agent tank 102 that stores the reducing agent 103, a reducing agent injector 108 that injects the reducing agent 103 into the exhaust of the engine 107, and the reducing agent 103 in the reducing agent tank 102. And a reducing agent supply pipe 104 for supplying to 108.

  The reducing agent tank 102 is equipped with a first reducing agent temperature sensor 109 that detects the reducing agent temperature in the reducing agent tank 102.

  The reducing agent injector 108 is installed on the exhaust upstream side of the selective catalytic reduction catalyst 111 in the middle of the exhaust pipe 110 of the engine 107.

  The reducing agent supply pipe 104 is connected between the reducing agent tank 102 and the reducing agent injector 108.

  The heater 105 is mounted on a supply module 112 installed in the middle of the reducing agent supply pipe 104. However, the heater 105 may be installed at any location of the reducing agent supply pipe 104 in addition to being mounted on the supply module 112.

  The supply module 112 is equipped with a second reducing agent temperature sensor 113 that detects the reducing agent temperature in the reducing agent supply pipe 104. However, the second reducing agent temperature sensor 113 may be installed at any location of the reducing agent supply pipe 104 in addition to being mounted on the supply module 112. Further, it is possible to install only the first reducing agent temperature sensor 109 without installing the second reducing agent temperature sensor 113.

  The reducing agent thawing device 100 includes a heater output changing unit 114. The heater output changing unit 114 is mounted on the controller 106.

  The heater output changing unit 114 changes the heater output according to the reducing agent temperature in the reducing agent tank 102.

  Specifically, the heater output changing unit 114 changes the heater output when the reducing agent temperature in the reducing agent tank 102 during the thawing of the reducing agent 103 in the reducing agent supply pipe 104 is less than the first temperature threshold. One heater output (for example, maximum output), and when the reducing agent temperature in the reducing agent tank 102 during the thawing of the reducing agent 103 in the reducing agent supply pipe 104 is equal to or higher than the first temperature threshold, the heater output is the first heater. Compared to the output, the second heater output is a low output.

  The heater output changing unit 114 determines the first temperature threshold based on the battery voltage, the reducing agent temperature, the outside air temperature, the reducing agent remaining amount, and the reducing agent concentration.

  For example, when the battery voltage is high, the reducing agent temperature or the outside air temperature is high, and the remaining amount of the reducing agent is large, the total amount of heat given to the parts arranged in the vicinity of the heater 105 becomes large, and the parts arranged in the vicinity of the heater 105 Therefore, the heater output is set to the lowest possible output by setting the first temperature threshold to a small value.

  The second heater output is set to a sufficiently low output so that the total amount of heat given to the components arranged in the vicinity of the heater 105 does not exceed the amount of heat that may cause the components arranged in the vicinity of the heater 105 to be overheated. Is done.

  Since the engine coolant temperature varies depending on the engine operating state, it is difficult to adjust the amount of heat given by the engine coolant, but the heater output can be arbitrarily adjusted, so the amount of heat given by the heater 105. It is easy to adjust.

  Therefore, in the reducing agent thawing device 100, the total amount of heat given to the components arranged in the vicinity of the heater 105 is arranged in the vicinity of the heater 105 by appropriately setting the first temperature threshold and the second heater output. It is possible to suppress the amount of heat exceeding the amount of heat that may cause an overheated part to reach an overheated state.

  In addition, the heater output changing unit 114 determines the temperature of the reducing agent in the reducing agent tank 102 during the temperature of the reducing agent 103 in the reducing agent supply pipe 104 after the thawing of the reducing agent 103 in the reducing agent supply pipe 104 is completed. When the temperature is less than the second temperature threshold, the heater output is set to the third heater output, and the reducing agent 103 in the reducing agent supply pipe 104 after the thawing of the reducing agent 103 in the reducing agent supply pipe 104 has been completed. When the reducing agent temperature in the agent tank 102 is equal to or higher than the second temperature threshold, the heater output is compared with the third heater output to obtain a low output fourth heater output.

  The heater output changing unit 114 determines the second temperature threshold based on the battery voltage, the reducing agent temperature, the outside air temperature, the reducing agent remaining amount, and the reducing agent concentration.

  For example, when the battery voltage is high, the reducing agent temperature or the outside air temperature is high, and the remaining amount of the reducing agent is large, the total amount of heat given to the parts arranged in the vicinity of the heater 105 becomes large, and the parts arranged in the vicinity of the heater 105 Therefore, the heater output is set to the lowest possible value by setting the second temperature threshold value to a small value.

  The third heater output is set according to the outside air temperature. When the outside temperature is high, the reducing agent 103 in the reducing agent supply pipe 104 can be kept warm without setting the third heater output to a high output, so the third heater output is set to a relatively low output. However, when the outside air temperature is low, the third heater output is relatively high because the reducing agent 103 in the reducing agent supply pipe 104 cannot be kept warm unless the third heater output is set to a high output. Set to

  The fourth heater output is set to a sufficiently low output so that the total amount of heat given to the components arranged in the vicinity of the heater 105 does not exceed the amount of heat that may cause the components arranged in the vicinity of the heater 105 to be overheated. Is done.

  Since the engine coolant temperature varies depending on the engine operating state, it is difficult to adjust the amount of heat given by the engine coolant, but the heater output can be arbitrarily adjusted, so the amount of heat given by the heater 105. It is easy to adjust.

  Therefore, in the reducing agent thawing device 100, the total amount of heat given to the components arranged in the vicinity of the heater 105 is arranged in the vicinity of the heater 105 by appropriately setting the second temperature threshold and the fourth heater output. It is possible to suppress the amount of heat exceeding the amount of heat that may cause an overheated part to reach an overheated state.

  Further, the heater output changing unit 114 determines that the thawing of the reducing agent 103 has been completed when the reducing agent temperature is equal to or higher than a predetermined temperature. However, the heater output changing unit 114 may determine that the thawing of the reducing agent 103 is complete when the thawing of the reducing agent 103 is continued for a predetermined time or when a predetermined amount of heat is applied to the reducing agent 103. Absent. The amount of heat can be calculated based on the driving time of the heater 105 and the heater output.

  More specifically, the heater output changing unit 114 sets the reducing agent 103 in the reducing agent supply pipe 104 when the reducing agent temperature in the reducing agent supply pipe 104 is equal to or higher than a predetermined temperature (for example, the melting point or higher). Determine that thawing is complete.

  Further, the heater output changing unit 114 is configured so that the reducing agent 103 in the reducing agent supply pipe 104 is thawed for a predetermined time (for example, several minutes to several tens of minutes) or the reducing agent in the reducing agent supply pipe 104. When a predetermined amount of heat (for example, the amount of heat assumed that the frozen reducing agent 103 reaches a liquid) is applied to the portion 103, it may be determined that thawing of the reducing agent 103 in the reducing agent supply pipe 104 has been completed. .

  In particular, when only the first reducing agent temperature sensor 109 is installed without installing the second reducing agent temperature sensor 113, the heater output changing unit 114 defrosts the reducing agent 103 in the reducing agent supply pipe 104 for a predetermined time. If the predetermined amount of heat is applied to the reducing agent 103 in the reducing agent supply pipe 104, it is determined that the thawing of the reducing agent 103 in the reducing agent supply pipe 104 has been completed.

  Further, the heater output changing unit 114 has a low outside air temperature or reducing agent temperature after the thawing of the reducing agent 103 in the reducing agent supply pipe 104 is completed, and the reducing agent 103 in the reducing agent supply pipe 104 may be re-frozen. When there is, it is determined that the reducing agent 103 in the reducing agent supply pipe 104 needs to be kept warm, the outside air temperature after the thawing of the reducing agent 103 in the reducing agent supply pipe 104 is completed, or the reducing agent temperature is high. When there is no possibility that the reducing agent 103 in the agent supply pipe 104 is frozen again, it is determined that it is unnecessary to keep the reducing agent 103 in the reducing agent supply pipe 104 warm.

  Next, the procedure for thawing the reducing agent 103 in the reducing agent supply pipe 104 using the reducing agent thawing apparatus 100 and the reduction in the reducing agent supply pipe 104 after the thawing of the reducing agent 103 in the reducing agent supply pipe 104 is completed. The procedure for keeping the agent 103 warm will be described.

  As shown in FIG. 2, the reducing agent thawing device 100 starts the thawing and warming control M200 by turning on the ignition key, and ends the thawing and warming control M200 by turning off the ignition key.

  In the first step S201, it is determined whether or not the defrosting of the reducing agent 103 in the reducing agent supply pipe 104 is completed by the heater output changing unit 114, and the reducing agent 103 in the reducing agent supply pipe 104 is defrosted. If it is determined that the reducing agent 103 in the reducing agent supply pipe 104 has been thawed, the process proceeds to step S205.

  In step S202, the heater output changing unit 114 determines whether or not the reducing agent temperature in the reducing agent tank 102 is equal to or higher than the first temperature threshold, and the reducing agent temperature in the reducing agent tank 102 is less than the first temperature threshold. In this case, the process returns to step S201 via step S203. If the reducing agent temperature in the reducing agent tank 102 is equal to or higher than the first temperature threshold, the process returns to step S201 via step S204.

  Note that the first temperature threshold is determined based on the battery voltage, the reducing agent temperature, the outside air temperature, the reducing agent remaining amount, and the reducing agent concentration when step S202 is executed.

  In step S203, the heater output changing unit 114 sets the heater output to the first heater output (for example, maximum output).

  In step S204, the heater output changing unit 114 compares the heater output with the first heater output to obtain a low output second heater output. Therefore, when the reducing agent temperature in the reducing agent tank 102 is high and there is a possibility that the parts arranged in the vicinity of the heater 105 are overheated, the heater output is set to a low output, so that the heater is arranged in the vicinity of the heater 105. It is possible to suppress the parts from being overheated.

  In step S205, the heater output changing unit 114 determines whether or not it is necessary to keep the reducing agent 103 in the reducing agent supply pipe 104 warm, and judges that it is unnecessary to keep the reducing agent 103 in the reducing agent supply pipe 104 warm. If it is determined, the process returns to step S201 via step S206. If it is determined that the reducing agent 103 in the reducing agent supply pipe 104 needs to be kept warm, the process proceeds to step S207.

  In step S206, the heater output changing unit 114 sets the heater output to zero.

  In step S207, the heater output changing unit 114 determines whether or not the reducing agent temperature in the reducing agent tank 102 is equal to or higher than the second temperature threshold, and the reducing agent temperature in the reducing agent tank 102 is less than the second temperature threshold. In this case, the process returns to step S205 via step S208. If the reducing agent temperature in the reducing agent tank 102 is equal to or higher than the second temperature threshold, the process returns to step S205 via step S209.

  The second temperature threshold is determined based on the battery voltage, the reducing agent temperature, the outside air temperature, the reducing agent remaining amount, and the reducing agent concentration when step S207 is executed.

  In step S208, the heater output changing unit 114 sets the heater output as the third heater output.

  The third heater output is set according to the outside air temperature when executing step S208.

  In step S209, the heater output changing unit 114 compares the heater output with the third heater output to obtain a low output fourth heater output. Therefore, when the reducing agent temperature in the reducing agent tank 102 is high and there is a possibility that the parts arranged in the vicinity of the heater 105 are overheated, the heater output is set to a low output, so that the heater is arranged in the vicinity of the heater 105. It is possible to suppress the parts from being overheated.

  As described above, in the reducing agent thawing device 100, the heater output is changed in accordance with the reducing agent temperature in the reducing agent tank 102. Therefore, even if the reducing agent temperature in the reducing agent tank 102 is high, the heater 105 It is possible to prevent the parts arranged in the vicinity of from being overheated.

100 reducing agent thawing device 101 selective catalyst reduction system 102 reducing agent tank 103 reducing agent 104 reducing agent supply piping 105 heater 106 controller 107 engine 108 reducing agent injector 109 first reducing agent temperature sensor 110 exhaust pipe 111 selective catalyst reduction catalyst 112 supply module 113 Second reducing agent temperature sensor 114 Heater output change unit 115 Intake pipe 116 Intake temperature sensor

Claims (5)

In a reducing agent thawing apparatus in which a heater is used when thawing a reducing agent in a reducing agent supply pipe of a selective catalyst reduction system,
A reducing agent thawing apparatus comprising: a heater output changing unit that changes a heater output according to a reducing agent temperature in a reducing agent tank of the selective catalyst reduction system. When the reducing agent temperature in the reducing agent tank during thawing of the reducing agent in the reducing agent supply pipe is less than a first temperature threshold, the heater output changing unit sets the heater output as the first heater output, and reduces the reducing agent. When the reducing agent temperature in the reducing agent tank during thawing of the reducing agent in the agent supply pipe is equal to or higher than the first temperature threshold, the heater output is compared with the first heater output, The reducing agent thawing device according to claim 1. The reducing agent thawing device according to claim 2, wherein the heater output changing unit determines the first temperature threshold based on a battery voltage, a reducing agent temperature, an outside air temperature, a reducing agent remaining amount, and a reducing agent concentration. The heater output changing unit is configured such that the reducing agent temperature in the reducing agent tank during the retention of the reducing agent in the reducing agent supply pipe after the thawing of the reducing agent in the reducing agent supply pipe is completed is a second temperature threshold value. If less than, the heater output is set as the third heater output, and the reducing agent in the reducing agent tank is kept warm while the reducing agent in the reducing agent supply pipe is being thawed after thawing of the reducing agent in the reducing agent supply pipe is completed. 4. The reducing agent thawing device according to claim 1, wherein when the agent temperature is equal to or higher than the second temperature threshold value, the heater output is compared with the third heater output to obtain a low output fourth heater output. 5. . The reducing agent thawing device according to claim 4, wherein the heater output changing unit determines the second temperature threshold based on a battery voltage, a reducing agent temperature, an outside air temperature, a reducing agent remaining amount, and a reducing agent concentration.

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