JP2014173750A - Burner and method for controlling the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a burner and a control method of the burner, in which generation of mixed air is started at timing suited to ignition of the mixed air.SOLUTION: A burner 20 controls an injection nozzle 39 for supplying a fuel, a first introduction hole 34 for supplying air, a glow plug 50 for igniting mixed air of the fuel and air, injection of the fuel from the injection nozzle 39 and supply of power from a power supply device 52 to the glow plug 50, and after raising a temperature of the glow plug 50 to a temperature capable of igniting the mixed air, starts generation of the mixed air. A burner control part acquires a voltage value and a current value for the glow plug 50 and calculates a resistance value of the glow plug 50 on the basis of the acquired voltage value and current value. Under a condition where the resistance value arrives at a target value allowing ignition of the mixed air, injection of the fuel from the injection nozzle 39 is started.

Description

  The technology of the present disclosure relates to a burner that ignites an air-fuel mixture with a glow plug and a method for controlling the burner.

  In a diesel particulate filter (DPF: Diesel Particulate Filter) attached to the exhaust passage of a diesel engine, a regeneration process is performed in which the fine particles captured by the DPF are incinerated in order to maintain the function of capturing the fine particles. For example, in the exhaust emission control device described in Patent Document 1, a burner disposed in front of the DPF in the exhaust passage injects fuel into the exhaust flowing through the exhaust passage and uses surplus oxygen contained in the exhaust. Fuel is burning. The burner is equipped with a glow plug that generates heat when energized and a thermocouple that detects the temperature of the glow plug, and fuel is injected after the temperature of the glow plug is raised to the temperature at which the mixture of exhaust gas and fuel ignites. Is done. As a method of generating an air-fuel mixture, a method of generating an air-fuel mixture for the purpose of increasing the amount of heat per unit time given to exhaust gas is also known.

JP 59-158309 A

  By the way, since a normal gap is usually formed between the ignition part of the glow plug and the thermocouple, there is a considerable error between the actual temperature in the ignition part and the temperature detected by the thermocouple. And when the temperature which a thermocouple detects is higher than the actual temperature in an ignition part, even if air-fuel | gaseous mixture is produced | generated, the problem that it will not lead to ignition of air-fuel | gaseous mixture is caused. Alternatively, when the temperature detected by the thermocouple is lower than the actual temperature in the ignition part, there is a problem that the temperature of the ignition part is unnecessarily increased without generating an air-fuel mixture.

  An object of the technology of the present disclosure is to provide a burner in which generation of an air-fuel mixture is started at a timing suitable for ignition of the air-fuel mixture and a method for controlling the burner.

  A burner that solves the above-described problem is a generator that generates an air-fuel mixture, a glow plug that ignites the air-fuel mixture, and a resistance value of the glow plug that reaches a target value for igniting the air-fuel mixture. A controller that causes the generator to start generating the air-fuel mixture.

  A method for controlling a burner that solves the above problem includes a step of generating an air-fuel mixture and a step of igniting the air-fuel mixture with a glow plug. In the step of generating the air-fuel mixture, a resistance value of the glow plug is Generation of the air-fuel mixture is started when a target value for igniting the air-fuel mixture is reached.

  The resistance value of the glow plug is a value uniquely determined as a function of the temperature of the glow plug. Then, according to the glow plug and the glow plug control method, the generation of the air-fuel mixture is started when the resistance value of the glow plug determined by the temperature of the glow plug reaches the target value. Therefore, compared with the case where the temperature of the glow plug is detected indirectly by a thermocouple or the like, the generation of the air-fuel mixture is started when the state of the glow plug is suitable for the ignition of the air-fuel mixture.

  In the burner, the generation unit includes a fuel supply unit that supplies fuel constituting the air-fuel mixture to the glow plug, and an air supply unit that supplies air constituting the air-fuel mixture to the glow plug, When the resistance value of the glow plug reaches the target value, the control unit starts supplying the fuel to the fuel supply unit and before supplying the fuel supply unit with the fuel supply, It is preferable that the air supply unit starts supplying the air.

  According to this configuration, air is already supplied to the glow plug before the resistance value of the glow plug reaches the target value. Therefore, the temperature drop of the glow plug after the fuel is supplied can be suppressed as compared with the case where the supply of air is started after the resistance value of the glow plug reaches the target value. As a result, the stability of the air-fuel mixture ignition is enhanced.

  The burner further includes a detection unit that detects whether or not the air-fuel mixture is combusted, and the control unit combusts the air-fuel mixture after the resistance value of the glow plug reaches the target value. It is preferable that a voltage for maintaining the resistance value at the target value is applied to the glow plug by controlling an output of a power supply device that applies a voltage to the glow plug until the detection unit detects that the glow plug is present.

  According to this configuration, the voltage for maintaining the resistance value at the target value is applied to the glow plug from when the fuel is supplied until the air-fuel mixture starts to burn. For this reason, the stability of ignition of the air-fuel mixture is improved, and the failure of the glow plug due to the excessive increase in the resistance value of the glow plug is suppressed.

  In the burner, when the detection unit detects that the air-fuel mixture is burning, the control unit preferably controls the output of the power supply device to stop the application of voltage to the glow plug.

  According to this configuration, since the voltage application to the glow plug is stopped when the air-fuel mixture is combusting, the air-fuel mixture can continue to be combusted even if the voltage application to the glow plug is stopped. is there. Therefore, when the air-fuel mixture continues to burn, the power consumed by the glow plug is suppressed.

  The burner further includes a voltage detection unit that detects a voltage applied to the glow plug as a voltage detection value, and a current detection unit that detects a current flowing through the glow plug as a current detection value. The control unit sets a threshold value of the current indicating disconnection in the glow plug, and calculates the resistance value using the voltage detection value and the current detection value when the current detection value exceeds the threshold value. It is preferable that the generation of the air-fuel mixture is prohibited when the detection value of the current detection unit is not more than the threshold value.

  In a state where the glow plug is disconnected, even if a voltage is applied to the glow plug, the temperature of the glow plug does not reach the temperature at which the air-fuel mixture ignites. According to this configuration, since the generation of the air-fuel mixture based on the resistance value is started in a state where the glow plug is not disconnected, the glow plug is disconnected from the target of the opportunity for the air-fuel mixture to be generated. Excluded. Therefore, the generation of the air-fuel mixture is started at a timing more suitable for the ignition of the air-fuel mixture.

It is a block diagram which shows the structure of one Embodiment which actualized the burner in the technique of this indication. It is a functional block diagram which shows the electric structure of a burner. It is a graph which shows an example of the relationship between the temperature of a glow plug, and resistance value. It is a flowchart which shows the process sequence of a reproduction | regeneration process. It is a flowchart which shows the process sequence of a temperature rising process. It is a flowchart which shows the process sequence of a stop process.

Hereinafter, with reference to FIGS. 1-6, one Embodiment of the control method of the burner in this indication and a burner is described.
As shown in FIG. 1, a DPF 12 that adsorbs particulates contained in the exhaust is mounted in the exhaust passage 11 of the diesel engine 10. The DPF 12 has a honeycomb structure made of, for example, porous silicon carbide, and traps particulates in the exhaust inside thereof. A compressor 15 that rotates together with the turbine 14 is connected to the turbine 14 connected to the exhaust passage 11, and a burner 20 is connected to the compressor 15 through the intake passage 13. The burner 20 is connected to a preceding stage on the side where exhaust gas is supplied to the DPF 12, and burns fuel and air supplied from the intake passage 13 to raise the temperature of the exhaust gas flowing into the DPF 12. Execute.

  The burner 20 has a double cylinder structure including a cylindrical cylinder portion 21 and a cylinder portion 22 having an inner diameter larger than that of the cylinder portion 21. The base end side ends of the cylindrical portions 21 and 22 are fixed to a substrate 23 that closes the openings of both base end ends. An annular closing plate 24 that closes the gap between the tubular portion 21 and the tubular portion 22 is fixed to the end portions of the tubular portions 21 and 22. A substantially annular ejection plate 25 is connected to the closing plate 24, and an ejection port 26 is formed at the center of the ejection plate 25.

  A partition wall 29 is attached to the inside of the cylinder part 21, and the partition wall 29 divides the internal space of the cylinder part 21 into a premixing chamber 27 in which an air-fuel mixture is generated and a combustion chamber 28 in which the air-fuel mixture burns. Partition. The partition wall 29 is a perforated plate having a disk shape, and the outer peripheral edge of the partition wall 29 is joined to the inner peripheral surface of the cylindrical portion 21. A plurality of communication passages 30 communicating with the premixing chamber 27 and the combustion chamber 28 penetrate the partition wall 29 in the thickness direction.

  The downstream end of the air supply passage 31 is connected to the outer peripheral surface of the cylindrical portion 22 on the tip side of the partition wall 29. The upstream end of the air supply passage 31 is connected to the downstream of the compressor 15, and an air valve 32 as an air supply unit constituting the generation unit is attached to the air supply passage 31. When the air valve 32 is in the open state, a part of the intake air flowing through the intake passage 13 is supplied as combustion air to the air introduction chamber 33 that is a gap between the cylinder part 21 and the cylinder part 22. When the air valve 32 is in a closed state, the supply of combustion air to the air introduction chamber 33 is stopped.

  A plurality of first introduction holes 34 communicating the air introduction chamber 33 and the premixing chamber 27 are formed over the entire circumferential direction of the cylinder portion 21 on the proximal end side of the peripheral wall of the cylinder portion 21 with respect to the partition wall 29. Has been. In addition, a plurality of second introduction holes 35 communicating with the air introduction chamber 33 and the combustion chamber 28 are formed over the entire circumferential direction of the cylinder portion 21 on the distal end side of the peripheral wall of the cylinder portion 21 with respect to the partition wall 29. Has been. The combustion air in the air introduction chamber 33 is introduced into the premixing chamber 27 through the first introduction hole 34 and also introduced into the combustion chamber 28 through the second introduction hole 35.

  An injection nozzle 39 as a fuel supply unit that constitutes the generation unit is fixed to the central portion of the substrate 23. Part of the fuel in the fuel tank 40 is fed into the injection nozzle 39 through the fuel supply passage 41. A fuel pump 42, a fuel pressure sensor 43, a fuel temperature sensor 44, a fuel valve 45, and an electric heater 46 are attached to the fuel supply passage 41. The fuel pump 42 is a mechanical pump that uses the engine 10 as a power source. The fuel pressure sensor 43 detects a fuel pressure Pf that is the pressure of fuel flowing through the fuel supply passage 41, and the fuel temperature sensor 44 detects a fuel temperature Tf that is the temperature of fuel flowing through the fuel supply passage 41. The fuel valve 45 is an electromagnetic valve that opens and closes the fuel supply passage 41 by duty control. The electric heater 46 generates heat according to the supplied power W that is the power supplied from the power supply device 47, and heats the fuel flowing through the fuel supply passage 41 to vaporize the fuel. The injection nozzle 39 injects vaporized fuel fed from the electric heater 46 into the premixing chamber 27.

  A glow plug 50 and a temperature sensor 55 as a detection unit are attached to the cylindrical portion 22. The ignition part 51 in the glow plug 50 is disposed closer to the partition wall 29 than the position facing the second introduction hole 35 in the combustion chamber 28. The ignition unit 51 incorporates a resistor that generates heat according to the voltage applied from the power supply device 52. The temperature sensor 55 is disposed in the combustion chamber 28 closer to the ejection port 26 than the ignition unit 51, and detects the combustion room temperature Tr that is the temperature in the combustion chamber 28. The temperature of the resistor incorporated in the ignition unit 51 is set as the glow plug temperature.

  The air-fuel mixture generated in the premixing chamber 27 flows into the combustion chamber 28 through the communication passage 30 of the partition wall 29 and is then ignited by being heated by the ignition portion 51 of the glow plug 50. Thereby, in the combustion chamber 28, the air-fuel mixture burns, and combustion gas that is the air-fuel mixture after combustion is generated. The generated combustion gas flows toward the exhaust passage 11 through the ejection port 26, and flows into the exhaust passage 11 at the junction 11 a of the exhaust passage 11. The temperature in the combustion chamber 28 when the combustion of the air-fuel mixture is ensured in the combustion chamber 28 is set as the combustion start temperature Tr1, and when the combustion of the air-fuel mixture is continued, the temperature in the combustion chamber 28 is The combustion start temperature Tr1 is increased.

Next, an electrical configuration of the burner 20 will be described with reference to FIGS.
In the burner 20, the fuel valve 45 is opened / closed, the air valve 32 is opened / closed, the power supplied to the electric heater 46, and the applied voltage Va applied to the resistor of the ignition unit 51. , Simply referred to as the control unit 70).

  The control unit 70 includes a CPU, a ROM in which various control programs and various data are stored, a RAM in which various calculation results and various data are temporarily stored, and the like, and is based on each control program stored in the ROM. Each unit functions to execute various processes. Here, the operation mode of the burner 20 will be described with reference to an example of a regeneration process that is a process of incinerating fine particles adhering to the DPF 12. In the regeneration process, in addition to a process for generating combustion gas, a temperature rise process for raising the temperature of the glow plug 50, a stop process for stopping the application of voltage to the resistor of the ignition unit 51, and disconnection of the glow plug 50 are detected. Disconnection detection processing is included.

As shown in FIG. 2, the control unit 70 executes an acquisition process for acquiring various data required for the reproduction process from various sensors 61 at a predetermined control cycle.
The data acquired from the various sensors 61 include the upstream exhaust flow rate Qe1, which is the flow rate of the exhaust flowing between the turbine 14 and the merging portion 11a, and the pressure of the exhaust flowing between the turbine 14 and the merging portion 11a. The upstream exhaust pressure Pe1 and the upstream exhaust temperature Te1 that is the temperature of the exhaust flowing between the turbine 14 and the merging portion 11a are included. The data acquired from the various sensors 61 include DPF temperature Td, which is the temperature of the DPF 12, downstream exhaust pressure Pe2, which is exhaust pressure downstream of the DPF 12, and intake air, which is the amount of air flowing into the compressor 15. The air amount Qa is included. The data acquired from the various sensors 61 includes an air circulation amount Qad that is the amount of air flowing through the air supply passage 31 and an air temperature Tad that is the temperature of the air.

  Further, the control unit 70 acquires the fuel pressure Pf from the fuel pressure sensor 43 and acquires the fuel temperature Tf from the fuel temperature sensor 44 at every predetermined control cycle. Moreover, the control part 70 acquires the value of the voltage applied to the resistor of the ignition part 51 as the voltage detection value V from the voltage sensor 62 which is a voltage detection part for every predetermined control period. Further, the control unit 70 acquires the value of the current flowing through the resistor of the ignition unit 51 as the current detection value I from the current sensor 63 that is a current detection unit, and acquires the combustion room temperature Tr from the temperature sensor 55.

  The control unit 70 calculates the accumulation amount M of fine particles in the DPF 12 based on the differential pressure ΔP between the upstream exhaust pressure Pe1 and the downstream exhaust pressure Pe2 and the upstream exhaust flow rate Qe1. The controller 70 starts the regeneration process of the DPF 12 when the calculated accumulation amount M becomes higher than a preset threshold value α. On the other hand, the control unit 70 has a threshold β that can be determined that the particulate accumulation amount M calculated during the regeneration process is a preset threshold and the particulates accumulated in the DPF 12 are sufficiently incinerated. When it becomes lower than <α), the reproduction process is terminated.

  When the temperature raising process is completed in the regeneration process, the fuel valve control unit 71 constituting the control unit 70 opens and closes the closed fuel valve 45 by duty control and starts supplying fuel. At this time, the fuel valve control unit 71 sets the upstream side exhaust flow rate Qe1, the upstream side exhaust temperature Te1, the air flow rate Qad, the air temperature Tad, the DPF temperature Td, the target temperature of the DPF 12, and the premixing chamber 27 based on these. A fuel supply amount Qf, which is a mass flow rate of fuel per unit time to be supplied to is calculated. The fuel supply amount Qf is the amount of fuel necessary to raise the temperature of the exhaust gas flowing into the DPF 12 to raise the temperature of the DPF 12 to the target temperature, and is the amount of fuel supplied to the fuel supply passage 41. Then, the fuel valve control unit 71 controls the opening and closing of the fuel valve 45 so that fuel corresponding to the fuel supply amount Qf is supplied to the premixing chamber 27 based on the fuel pressure Pf and the fuel temperature Tf. When the accumulation amount M of particulates calculated during the regeneration process is lower than the threshold value β, the fuel valve control unit 71 controls the fuel valve 45 to be closed, and ends the fuel valve 45 opening / closing control.

  The power control unit 72 constituting the control unit 70 starts supplying power control to the electric heater 46 when the temperature raising process is completed in the regeneration process. At this time, the power control unit 72 calculates the supply power W necessary for vaporizing the fuel corresponding to the fuel supply amount Qf based on the fuel supply amount Qf. The power control unit 72 controls the power supply device 47 so that the calculated supply power W is supplied to the electric heater 46. The power control unit 72 ends the supply of power from the power supply device 47 to the electric heater 46 when the accumulation amount M of the fine particles calculated during the regeneration process is lower than the threshold value β.

  The air valve control unit 73 constituting the control unit 70 starts opening control of the air valve 32 when the regeneration process is started. The air valve control unit 73 controls the air valve 32 to a predetermined opening degree until the temperature raising process is completed. Further, the air valve control unit 73 uses an air amount corresponding to the fuel supply amount Qf, that is, an air amount per unit time necessary for burning fuel corresponding to the fuel supply amount Qf when the temperature raising process is completed. A certain air supply amount Qs is calculated. The air valve control unit 73 controls the opening degree of the air valve 32 based on the intake air amount Qa, the air circulation amount Qad, and the air temperature Tad so that air is supplied to the burner 20 by the air supply amount Qs. . The air valve control unit 73 closes the air valve 32 and ends the opening control of the air valve 32 when the accumulation amount M of particulates calculated during the regeneration process is lower than the threshold value β.

  The voltage control unit 74 constituting the control unit 70 continuously performs the temperature raising process and the stop process of the glow plug 50 when the regeneration process is started. At this time, the voltage control unit 74 calculates a voltage instruction value V1 that is a value of a voltage applied to the glow plug 50, and outputs a control signal for outputting the applied voltage Va corresponding to the voltage instruction value V1. Output to. The power supply device 52 applies an applied voltage Va corresponding to the voltage instruction value V <b> 1 to the glow plug 50 in accordance with a control signal from the voltage control unit 74.

Comparison data 76 is stored in the storage unit 75 constituting the control unit 70, and the comparison data 76 is used for calculation of the voltage instruction value V <b> 1 by the voltage control unit 74.
Next, the voltage instruction value V1 calculated by the voltage controller 74 will be described with reference to FIG. FIG. 3 is a graph showing the relationship between the glow plug temperature at which the air-fuel mixture can be ignited and the resistance value of the resistor at the glow plug temperature.

  As shown in FIG. 3, the lowest glow plug temperature among the glow plug temperatures capable of igniting the air-fuel mixture is set as the minimum ignition temperature Tmin. The state of the burner 20 when the air-fuel mixture is ignited at the minimum ignition temperature Tmin is, for example, a state where the combustion air supplied to the combustion chamber 28 is the least, and the state of the engine 10 is an idling state. . In the resistor built in the ignition unit 51, the resistance value of the resistor increases as the glow plug temperature, which is the temperature of the resistor, increases. When the glow plug temperature is the minimum ignition temperature Tmin, the resistance value of the resistor is The smallest.

  Here, the voltage control unit 74 calculates the resistance value obtained from the voltage detection value V and the current detection value I as the calculation value Rc, and applies it to the resistor so that the calculation value Rc becomes the target resistance value Rt. The applied voltage Va is controlled. The target temperature Tt that is the glow plug temperature corresponding to the target resistance value Rt is higher than the minimum ignition temperature Tmin, and is a temperature at which the air-fuel mixture ignites with a very high probability regardless of the operating state of the engine 10. The comparison data 76 stored in the storage unit 75 includes the target resistance value Rt as a target value, and further includes a combustion start temperature Tr1 as a combustion room temperature Tr indicating that the air-fuel mixture is combusting in the combustion chamber 28. include. In addition, the comparison data 76 stored in the storage unit 75 includes a current value indicating a disconnection in the glow plug 50 as a threshold value of the current detection value I.

  When the temperature raising process is started, the voltage control unit 74 outputs a control signal for setting the predetermined initial voltage value V0 to the voltage instruction value V1 to the power supply device 52. The initial voltage value V0 is a voltage value for the glow plug temperature to reach the minimum ignition temperature Tmin in a predetermined time, and is, for example, a value measured in advance in the idling state of the engine 10 that is cold-started. After the output of the control signal, the voltage control unit 74 acquires the voltage detection value V from the voltage sensor 62 and acquires the current detection value I from the current sensor 63. The voltage control unit 74 calculates the calculated value Rc using the detected voltage value V and the detected current value I, and compares the calculated value Rc with the target resistance value Rt.

  When the calculated value Rc does not reach the target resistance value Rt, the voltage control unit 74 calculates a voltage instruction value V1 that brings the calculated value Rc closer to the target resistance value Rt. For example, the voltage control unit 74 performs a PID process in which the current detection value I and the voltage detection value V are handled as output values, the target resistance value Rt is handled as a target value, and the voltage instruction value V1 is calculated as an input value. . That is, the voltage control unit 74 calculates a current value obtained from the voltage detection value V and the target resistance value Rt, calculates a voltage value obtained from the current value as the calculation result and the target resistance value Rt, and calculates the result. The voltage instruction value V1 is calculated by PID processing using a deviation between the voltage value and the voltage detection value V. Then, the voltage control unit 74 generates a control signal for applying the applied voltage Va corresponding to the voltage instruction value V <b> 1 to the resistor and outputs the control signal to the power supply device 52. When the calculated value Rc reaches the target resistance value Rt, the voltage control unit 74 ends the temperature increase process.

  The voltage control unit 74 performs a stop process following the temperature raising process. In the stop process, the voltage control unit 74 acquires the combustion room temperature Tr from the temperature sensor 55. The voltage control unit 74 compares the acquired combustion room temperature Tr with the combustion start temperature Tr <b> 1 included in the comparison data 76. When the combustion room temperature Tr is lower than the combustion start temperature Tr1, the voltage control unit 74 determines that the sustainability of the combustion of the air-fuel mixture is low, and sets the voltage instruction value V1 for maintaining the calculated value Rc at the target resistance value Rt. Calculation is performed by the PID process. Then, the voltage control unit 74 outputs a control signal for applying the applied voltage Va corresponding to the voltage instruction value V1 to the resistor to the power supply device 52. When the combustion room temperature Tr is equal to or higher than the combustion start temperature Tr1, the voltage control unit 74 determines that the combustion of the air-fuel mixture is sufficiently sustained, and a control signal for stopping the application of voltage to the glow plug 50 Is output to the power supply device 52, and the stop process is terminated.

  When executing the temperature raising process and the stop process of the glow plug 50, the control unit 70 executes the disconnection detection process of the glow plug 50 in parallel. In the disconnection detection process, the control unit 70 compares the current detection value I acquired from the current sensor 63 with the threshold value included in the comparison data 76. When the detected current value I is equal to or smaller than the threshold value, the control unit 70 determines that the resistor is disconnected, and forcibly ends the reproduction process being executed. Then, the control unit 70 turns on the alarm lamp 64 to notify the driver that the glow plug 50 has failed.

Next, with reference to FIG. 4, the procedure of the reproduction process executed by the control unit 70 will be described.
As shown in FIG. 4, when the regeneration process is started, the control unit 70 first opens the air valve 32 at a predetermined opening (step S11). As a result, combustion air is supplied to the combustion chamber 28. Subsequently, the control unit 70 executes a temperature raising process for raising the temperature of the glow plug 50 to the target temperature Tt (step S12).

  When the temperature raising process is completed, the control unit 70 acquires data necessary for executing the regeneration process from various sensors (step S13), and calculates the fuel supply amount Qf and the air supply amount Qs based on the data. (Step S14). Based on the fuel supply amount Qf and the air supply amount Qs, the control unit 70 performs the opening control of the air valve 32, the opening / closing control of the fuel valve 45, the power supply control to the electric heater 46, and the like. Fuel is supplied to 28 and combustion air is supplied (step S15). As a result, the generation of the air-fuel mixture is started in the premixing chamber 27, and the air-fuel mixture supplied is ignited by the glow plug 50 in the combustion chamber 28. Then, combustion gas, which is an air-fuel mixture after combustion, is supplied to the exhaust passage 11 through the ejection port 26, and the temperature of the exhaust gas flowing into the DPF 12 is raised.

  In step S16, the controller 70 obtains the upstream exhaust pressure Pe1, the upstream exhaust flow rate Qe1, and the downstream exhaust pressure Pe2 to calculate the deposition amount M. Then, in step S17, the control unit 70 determines whether or not the calculated accumulation amount M is lower than the threshold value β.

  When it is determined that the accumulation amount M is greater than or equal to the threshold value β (step S17: NO), the control unit 70 repeats the processing from step S13 to step S17. On the other hand, when the accumulation amount M is lower than the threshold β (step S17: YES), the control unit 70 controls the fuel valve 45 and the air valve 32 to be closed and power to the electric heater 46 in the next step S18. Is stopped and the reproduction process is terminated.

Next, with reference to FIG. 5, the processing procedure of the temperature raising process performed during the regeneration process will be described.
As shown in FIG. 5, first, the voltage control unit 74 of the control unit 70 outputs a control signal for applying the initial voltage value V0 to the power supply device 52 and applies the initial applied voltage to the resistor of the ignition unit 51. Va0 is applied (step S12-1).

  In the next step S12-2, the voltage control unit 74 acquires the voltage detection value V from the voltage sensor 62 and acquires the current detection value I from the current sensor 63. Then, the voltage control unit 74 calculates the calculation value Rc using the voltage detection value V and the current detection value I (step S12-3). Subsequently, the voltage control unit 74 compares the calculated value Rc with the target resistance value Rt, and determines whether or not the calculated value Rc has reached the target resistance value Rt (step S12-4). When the calculated value Rc is less than the target resistance value Rt (step S12-4: NO), the voltage control unit 74 calculates a voltage instruction value V1 that brings the calculated value Rc closer to the target resistance value Rt, and the calculated voltage instruction A control signal for applying the applied voltage Va corresponding to the value V1 is output to the power supply device 52 (step S12-5). And the voltage control part 74 transfers again to the process of step S12-2.

  On the other hand, when the calculated value Rc is higher than the target resistance value Rt (step S12-4: YES), the voltage control unit 74 determines that the glow plug temperature has reached the target temperature Tt and ends the temperature raising process. That is, in the temperature raising process, the voltage control unit 74 controls the applied voltage Va applied to the glow plug 50 until the temperature of the glow plug 50 reaches the target temperature Tt. When the glow plug temperature reaches the target temperature Tt, the generation of the air-fuel mixture is started by opening / closing control of the fuel valve 45.

Next, with reference to FIG. 6, the processing procedure of the stop process performed continuously with the temperature raising process will be described. This stop process is performed in the regeneration process after the temperature raising process is completed.
As shown in FIG. 6, the voltage control unit 74 of the control unit 70 acquires the combustion room temperature Tr based on the signal from the temperature sensor 55 (step S21), and uses the acquired combustion room temperature Tr and combustion start temperature Tr1. In comparison, it is determined whether or not the combustion room temperature Tr is lower than the combustion start temperature Tr1 (step S22).

  When the combustion room temperature Tr is lower than the combustion start temperature Tr1 (step S22: YES), the voltage controller 74 acquires the voltage detection value V from the voltage sensor 62 and acquires the current detection value I from the current sensor 63 (step). S23). Next, the voltage control unit 74 calculates a calculation value Rc based on the voltage detection value V and the current detection value I, and calculates a voltage instruction value V1 for keeping the calculation value Rc at the target resistance value Rt. Then, the voltage control unit 74 controls the applied voltage Va to the glow plug 50 by outputting to the power supply device 52 a control signal for applying the applied voltage Va corresponding to the calculated voltage instruction value V1 (step). S25). Thereafter, the voltage control unit 74 proceeds to the process of step S21 again.

  On the other hand, when the combustion room temperature Tr is equal to or higher than the combustion start temperature Tr1 (step S22: YES), the voltage control unit 74 applies voltage to the power supply device 52 on the assumption that the temperature of the glow plug 50 has reached the target temperature Tt. An end control signal is output to stop the glow plug 50 (step S26), and the stop process ends. That is, in the stop process, the voltage control unit 74 controls the voltage Va applied to the glow plug 50 so that the temperature of the glow plug 50 is maintained at the target temperature Tt, and the voltage to the glow plug 50 when the air-fuel mixture ignites. The application of is terminated.

As described above, according to the burner 20 and the control method of the burner 20 of the above embodiment, the effects listed below can be obtained.
(1) When the calculated value Rc, which is the resistance value of the resistor, reaches the target resistance value Rt, the fuel supply is started and the generation of the air-fuel mixture is started. The calculated value Rc, which is the resistance value of the glow plug 50, is a value that is uniquely determined as a function of the temperature of the glow plug 50, and therefore, compared with a case where the temperature of the glow plug 50 is indirectly detected by a thermocouple or the like. Thus, when the glow plug 50 is in a state suitable for the ignition of the air-fuel mixture, the generation of the air-fuel mixture is started.

  (2) The temperature increase process of the glow plug 50 is performed in a state where the combustion air is supplied to the combustion chamber 28. Therefore, when the calculated value Rc, which is the resistance value of the glow plug 50, reaches the target resistance value Rt, or after reaching the target resistance value Rt, the supply of combustion air is started. The temperature drop of the glow plug 50 after the start of fuel supply is suppressed. As a result, the ignition stability of the air-fuel mixture is improved.

  (3) In the temperature raising process, a voltage for bringing the calculated value Rc close to the target resistance value Rt is applied to the glow plug 50. In the stop process, a voltage for maintaining the calculated value Rc at the target resistance value Rt is applied to the glow plug 50. To be applied. As a result, the ignition stability of the air-fuel mixture is improved, and an excessive increase in the resistance value in the glow plug 50 is suppressed.

  (4) When the combustion room temperature Tr becomes equal to or higher than the combustion start temperature Tr1, application of voltage to the glow plug 50 is stopped. Therefore, even after the combustion room temperature Tr becomes equal to or higher than the combustion start temperature Tr1, power consumption for burning the air-fuel mixture is reduced as compared with the case where a voltage is applied to the glow plug 50.

  (5) Since the air-fuel mixture is generated by the fuel and air vaporized by the electric heater 46, the glow plug 50 by supplying the air-fuel mixture is compared with the case where the air-fuel mixture is generated by the liquefied fuel and air. The decrease in temperature is suppressed. Therefore, the stability of the air-fuel mixture ignition is further enhanced.

  (6) When the detected current value is equal to or lower than the threshold value in the temperature raising process and the stop process, the regeneration process is forcibly terminated and the alarm lamp 64 is turned on. Therefore, an increase in unburned fuel due to the failure of the glow plug 50 can be suppressed, and the driver can be notified of the failure of the glow plug 50 by turning on the alarm lamp 64.

In addition, the said embodiment can also be suitably changed and implemented as follows.
The calculated value Rc, which is the resistance value of the resistor of the glow plug 50, may be a resistance value obtained from the voltage instruction value V1 and the current detection value I.

The control of the temperature of the resistor in the glow plug 50 is not limited to the control of the voltage applied to the resistor, but may be the control of the current flowing through the resistor.
The condition for terminating the stop process is not limited to the combustion room temperature Tr being equal to or higher than the combustion start temperature Tr1, and a detection unit for detecting whether or not the air-fuel mixture is combusting is provided, and the air-fuel mixture is combusting. Any configuration may be used so long as the detection unit detects this. The detection unit that detects whether or not the air-fuel mixture is combusting may be, for example, a sensor that detects the degree of increase in the pressure of the combustion chamber.

  The condition for terminating the stop process is not limited to the combustion room temperature Tr being equal to or higher than the combustion start temperature Tr1, for example, the time that has elapsed since the end of the temperature raising process is a predetermined time that can ensure the combustion of the air-fuel mixture It may be to reach. The application of voltage to the glow plug 50 may be stopped immediately after the start of the generation of the air-fuel mixture.

  The applied voltage Va applied in the stop process may be a voltage value corresponding to the voltage instruction value V1 when the temperature raising process is finished, or may be a voltage instruction value V1 when the temperature raising process is finished. The voltage value may be higher than the corresponding voltage value. Furthermore, the applied voltage Va applied in the stop process may be a voltage value lower than a voltage value corresponding to the voltage instruction value V1 when the temperature raising process is completed.

  In the temperature raising process, a voltage may be applied to the glow plug 50 in an atmosphere in which the air valve 32 is kept closed and no air is supplied. In the temperature raising process, even if the opening degree of the air valve 32 is changed according to the operating state of the engine 10 based on the accelerator opening degree, the combustion injection amount to the engine 10, the engine rotation speed, the intake air amount Qa, and the like. Good.

The start of the generation of the air-fuel mixture is not limited to the start of the fuel supply, but may be the start of the supply of combustion air performed before the fuel supply is started.
For example, in an air-fuel mixture generation mode in which fuel is supplied after a predetermined time has elapsed from the start of combustion air supply, the start of fuel air supply is set as the start of air-fuel mixture generation. When the calculated value Rc, which is the resistance value of the resistor, reaches the target resistance value Rt, the supply of combustion air may be started.

  For example, even in an air-fuel mixture generation mode in which combustion air supply and fuel supply are performed simultaneously, the start of fuel air supply is set as the start of air-fuel mixture generation, and the resistance value of the resistor of the glow plug 50 When the calculated value Rc reaches the target resistance value Rt, the supply of combustion air may be started.

The generation of the air-fuel mixture is not limited to the mixture of combustion air and fuel, but may be the mixture of exhaust gas and fuel. At this time, the start of the air-fuel mixture generation is the same as in the above-described modification.
The burner on which the control unit 70 is mounted may be a burner in which the air-fuel mixture is ignited by the glow plug 50, and is not limited to the premix type burner in which the air-fuel mixture is generated in the premixing chamber 27, but the combustion chamber 28 Alternatively, a diffusion burner in which fuel is directly supplied may be used.

Further, the fuel injected from the injection nozzle 39 is not limited to the vaporized fuel, and may be a liquid fuel.
-Control part 70 may be one electronic control unit, and may be constituted by a plurality of electronic control units. For example, when the control unit 70 is configured by two electronic control units, a control signal indicating the start of the reproduction process and an end of the reproduction process are indicated from one electronic control unit to the other electronic control unit. A control signal may be output.

The temperature increase of the exhaust gas by the burner 20 is not limited to the regeneration process of the DPF 12, and may be applied to, for example, a catalyst temperature increase process for increasing the temperature of the catalyst provided in the exhaust purification device.
The engine to which the burner 20 is applied may be a gasoline engine. Further, the burner 20 is not limited to an engine, and may be applied to, for example, a heater.

  DESCRIPTION OF SYMBOLS 10 ... Diesel engine, 11 ... Exhaust passage, 11a ... Confluence | merging part, 12 ... DPF, 13 ... Intake passage, 14 ... Turbine, 15 ... Compressor, 20 ... Burner, 21, 22 ... Cylindrical part, 23 ... Substrate, 24 ... Blocking Plate 25, jet plate 26, jet port 27 27 premixing chamber 28 combustion chamber 29 partition wall 30 communication path 31 air supply passage 32 air valve 33 air introduction Chamber 34... First introduction hole 35. Second introduction hole 39. Injection nozzle 40 40 Fuel tank 41 Fuel supply passage 42 Fuel pump 43 Fuel pressure sensor 44 Fuel temperature sensor 45 DESCRIPTION OF SYMBOLS ... Fuel valve, 46 ... Electric heater, 47 ... Power supply device, 50 ... Glow plug, 51 ... Ignition part, 52 ... Power supply device, 55 ... Temperature sensor, 61 ... Sensor, 62 ... Current sensor, 63 ... Voltage sensor, 64 Warning lamp, 70 ... burner control unit, 71 ... fuel valve control unit, 72 ... power control unit, 73 ... air valve control unit, 74 ... voltage control unit, 75 ... storage unit, 76 ... comparison data.

Claims (6)

A generator for generating an air-fuel mixture;
A glow plug for igniting the air-fuel mixture;
A control unit that causes the generating unit to start generating the air-fuel mixture when a resistance value of the glow plug reaches a target value for igniting the air-fuel mixture;
With a burner. The generator is
A fuel supply section for supplying fuel constituting the air-fuel mixture to the glow plug;
An air supply unit for supplying air constituting the air-fuel mixture to the glow plug,
The controller is
When the resistance value of the glow plug reaches the target value, the fuel supply unit starts supplying the fuel, and before the fuel supply unit supplies the fuel supply, the air supply unit supplies the fuel supply unit with the fuel supply unit. The burner according to claim 1, wherein the supply of air is started. A detector for detecting whether or not the air-fuel mixture is burning;
The controller is
The output of the power supply device that applies a voltage to the glow plug is controlled until the detection unit detects that the air-fuel mixture is combusted after the resistance value of the glow plug reaches the target value. The burner according to claim 1 or 2, wherein a voltage for maintaining a resistance value at the target value is applied to the glow plug. The controller is
The burner according to claim 3, wherein when the detection unit detects that the air-fuel mixture is burning, the output of the power supply device is controlled to stop the application of voltage to the glow plug. A voltage detection unit for detecting a voltage applied to the glow plug as a voltage detection value;
A current detection unit that detects a current flowing through the glow plug as a current detection value;
Further comprising
The controller is
Setting a threshold of the current indicating a disconnection in the glow plug;
When the current detection value exceeds the threshold value, the resistance value is calculated using the voltage detection value and the current detection value,
The burner according to any one of claims 1 to 4, wherein generation of the air-fuel mixture is prohibited when a detection value of the current detection unit is equal to or less than the threshold value. Producing an air-fuel mixture;
Igniting the air-fuel mixture with a glow plug,
In the step of generating the air-fuel mixture,
A method for controlling a burner that starts generating the air-fuel mixture when a resistance value of the glow plug reaches a target value for igniting the air-fuel mixture.

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