A DPF system with a thermal energy injection device and its control method

Abstract

The present invention provides a DPF system with a thermal energy injection device and its control method, including: a controller, a DPF device, and a thermal energy injection device arranged upstream thereof. Among them, the thermal energy injection device includes: an inlet manifold with one end for receiving exhaust gas, the other end of the inlet manifold is connected to a first branch and a second branch, the other ends of the first branch and the second branch are connected to one end of an outlet manifold, and the other end of the outlet manifold is connected to a downstream DPF device, and transmits the exhaust gas processed by the thermal energy injection device to the downstream DPF device; a flow control valve for adjusting the flow ratio in the first branch and the second branch; a spraying point module for generating a high-temperature heat flow and a pre-stage small DOC catalyst are provided in the second branch; in the thermal energy injection device, there is also included: a downstream fuel injection device. In the DPF system of the present invention, the exhaust gas temperature flowing through the DPF can be controlled through two-stage closed-loop control.

Description

Technical Field

[0001] The present invention relates to a DPF system and a control method thereof, in particular to a DPF system with a heat energy injection device and a control method thereof. Background Art

[0002] In order to meet the requirements of emission regulations, a particulate trap (DPF) needs to be installed in the engine exhaust gas treatment system to remove the soot generated by combustion. Soot accumulates in the DPF and, to a certain extent, increases the back pressure of the engine system, affecting the operation of the engine. Therefore, in the DPF system, the soot therein also needs to be removed regularly. The process of removing soot from the DPF is called DPF regeneration. In diesel engine applications, DPF regeneration has two forms: passive regeneration and active regeneration. Passive regeneration is the reaction of nitrogen oxides (NOx) in the exhaust gas with soot, thereby removing the soot. Active regeneration is the reaction of the remaining oxygen in the exhaust gas with soot. Compared with active regeneration, passive regeneration requires a relatively low regeneration temperature, but the window is relatively narrow (the efficient range is between 300 and 350 degrees Celsius). At the same time, since the amount of NOx in the exhaust gas is not easy to control, the main regeneration form is usually active regeneration.

[0003] Passive regeneration generally requires the participation of an oxidation catalyst (such as platinum and palladium, etc.). In this process, the role of the oxidation catalyst is to generate NO2 to increase the reaction efficiency. Active regeneration can also be completed using an oxidation catalyst. In this process, hydrocarbon fuel is oxidized in the oxidation catalyst to generate heat to heat the exhaust gas, so that oxygen reacts with soot, thereby removing the soot. When using an oxidation catalyst for active regeneration, generally the oxidation catalyst is arranged in the form of an independent catalyst unit (diesel oxidation catalyst DOC) upstream of the DPF. At the same time, in order to improve the oxidation efficiency, noble metals are also coated on the DPF.

[0004] DPF active regeneration can use a burner. In the burner, fuel is ignited by a glow plug or a spark plug, and then a flame and a heat flow are formed to heat the exhaust gas. Similar to the DOC oxidation method (DOC needs to maintain the chamber temperature higher than the light-off temperature of the fuel on the catalyst when oxidizing the fuel), the combustion of fuel in the burner also requires a heat source (flame holder) or a heat environment (such as a hot air flow). The fuel is heated to the light-off temperature on the heat source or in the heat environment and then burns to release heat. If the heat released by the fuel combustion can maintain the temperature of the heat source and there is sufficient oxygen, the combustion can be maintained; otherwise, the fuel will burn incompletely and form new emissions. In an exhaust gas environment where the air flow, temperature, and oxygen concentration change rapidly, it is difficult to control fuel injection to maintain combustion. Therefore, in DPF applications, generally, the burner needs to use a fresh air source (with constant temperature and oxygen concentration), and low-cost burners are only used in single or simple working conditions (with constant or little change in flow). To eliminate the new emissions generated by incomplete combustion, a DOC is usually configured downstream of the burner. Due to these usage conditions, in DPF applications, unless there are strict requirements for regenerating low-temperature exhaust gas (exhaust gas below the light-off temperature of DOC), generally, the DPF system does not use a burner.

[0005] In the above-mentioned prior art system, there are problems of too high system cost and too high system complexity; and there is also a problem of too high soot loading caused by untimely regeneration. Summary of the Invention

[0006] Object of the Invention: The technical problem to be solved by the present invention is to provide a DPF system with a heat energy injection device and its control method in view of the deficiencies of the prior art.

[0007] To solve the above technical problems, the present invention discloses a DPF system with a heat energy injection device and its control method.

[0008] Among them, a DPF system with a heat energy injection device includes: a controller for controlling the system, a DPF device, and a heat energy injection device arranged upstream thereof. Among them, the heat energy injection device includes: an inlet manifold with one end for receiving exhaust gas, the other end of the inlet manifold is connected to a first branch and a second branch, the other ends of the first branch and the second branch are connected to one end of an outlet manifold, and the other end of the outlet manifold is connected to the downstream DPF device and transmits the exhaust gas processed by the heat energy injection device to the downstream DPF device;

[0009] A flow control valve for adjusting the flow ratio in the first branch and the second branch; a spray point module and a pre-stage small DOC catalyst for generating a high-temperature heat flow are arranged in the second branch; among them, the fuel injection amount of the spray point module is controlled by a first fuel flow control valve;

[0010] In the thermal energy injection device, it further includes: a downstream fuel injection device disposed in the first branch or the second branch; wherein, the fuel injection amount of the downstream fuel injection device is controlled by a second fuel flow control valve.

[0011] Furthermore, when the downstream fuel injection device, i.e., the fuel injection device (109), is disposed in the second branch (112), it is located downstream of the pre-stage small DOC catalyst (135), and a flame holder (110) is provided downstream thereof.

[0012] Furthermore, when the downstream fuel injection device, i.e., the fuel injection device, is disposed in the first branch, it is located downstream of the flow control valve, a mixer is provided in the outlet manifold, and the exhaust gas flow out of the first branch is uniformly mixed with the exhaust gas flow out of the second branch in the mixer.

[0013] Furthermore, in the thermal energy injection device, it further includes: an oxygenator is provided upstream of the injection point module in the second branch for injecting fresh air into the second branch.

[0014] Furthermore, the oxygenator is connected to an air source through a pipeline and a fresh air flow control valve.

[0015] Furthermore, the injection point module (108) is used for injecting fuel and igniting the injected fuel to generate a high-temperature heat flow, and includes: an air flow inlet hole, a fuel inlet channel, an electrothermal unit, and a flame holder.

[0016] Furthermore, the downstream fuel injection device, which is used for atomizing and injecting fuel, includes: a fuel delivery pipe for delivering fuel, and an atomizing nozzle for spraying the atomized fuel.

[0017] Furthermore, in the DPF device, it includes: a DOC sub-module and a DPF sub-module;

[0018] Wherein, the DOC sub-module and the DPF sub-module are independently provided, or the DOC sub-module and the DPF sub-module are provided by partitioning and coating noble metals on the carrier of the DPF, i.e., the DOConDPF method is adopted.

[0019] A control method for a DPF system with a thermal energy injection device, which is used to control the above-mentioned DPF system with a thermal energy injection device, includes the following steps:

[0020] Step 1, in the DPF system with a thermal energy injection device, set sensors to collect required data:

[0021] Step 2, determine whether the system is in the DPF regeneration or thermal management mode. If so, execute Step 3; otherwise, directly stop the control.

[0022] Step 3: Calculate the limit mf_max112 of the maximum fuel injection quantity and the fuel control command mc1 for controlling the first fuel flow control valve according to the values obtained by the sensor;

[0023] Calculate the total injection quantity mf_max and the fuel control command mc2 for controlling the second fuel flow control valve;

[0024] Step 4: Determine whether the following conditions are met, i.e.:

[0025] mc1 > mf_max112 or mc1 + mc2 > mf_max

[0026] If met, proceed to Step 5; otherwise, proceed to Step 6;

[0027] Step 5: Perform fresh air treatment and determine whether there is an error. If there is no error, return to Step 4; otherwise, proceed to Step 7;

[0028] Step 6: Set the control command of the first fuel flow control valve in the system to the fuel control command mc1, and determine: whether the time when the temperature Tb downstream of the pre - installed small DOC catalyst in the system is less than the first threshold ThdTl1 or greater than the second threshold ThdTh1 exceeds the preset duration. If so, proceed to Step 7; otherwise, proceed to Step 8;

[0029] Step 7: Reset the control commands of the first fuel flow control valve and the second fuel flow control valve to 0, then report an error and stop control;

[0030] Step 8: Set the control command of the second fuel flow control valve to the post - injection command mc2, and determine: whether the time when the temperature Td at the far downstream of the system, i.e., downstream of the DPF device in the system, is less than the third threshold ThdTl2 or greater than the fourth threshold ThdTh2 exceeds the preset duration. If so, proceed to Step 7; otherwise, return to execute Step 2.

[0031] Furthermore, the fresh air treatment described in Step 5 specifically includes the following steps:

[0032] Step 5 - 1: Determine whether there is a fresh air flow control valve in the system. If so, proceed to Step 5 - 2; otherwise, proceed to Step 5 - 3;

[0033] Step 5 - 2: Open the fresh air flow control valve and proceed to Step 5 - 3;

[0034] Step 5 - 3: Determine whether the following conditions are met:

[0035] Whether the duration of mc1 > mf_max112 or mc1 + mc2 > mf_max is greater than the preset duration. If so, report an error and stop control; otherwise, directly stop control.

[0036] Beneficial effects:

[0037] 1. The device proposed by the present invention uses an oxidation catalyst with a coating amount of precious metal as low as possible to heat the exhaust gas with a temperature lower than the light-off temperature of the DOC, thereby expanding the opportunity for DPF regeneration of the system at the lowest cost and reducing the problem of excessive soot loading caused by untimely regeneration.

[0038] 2. In the present invention, the oxygen in the exhaust gas is used as much as possible to oxidize the fuel, and oxygen is supplemented when the oxygen is insufficient, so that the system can complete DPF regeneration with the lowest fuel consumption.

[0039] 3. The present invention tries to reduce the heat flow temperature after fuel oxidation heating, thereby reducing the cost of the exhaust pipe.

[0040] 4. The present invention uses a system integrating DOC and DPF, thereby reducing the complexity of the system. Description of the drawings

[0041] The following further specifically describes the present invention in conjunction with the drawings and specific embodiments, and the above and / or other advantages of the present invention will become clearer.

[0042] Figure 1a It is a structural block diagram of a DPF system with a TI device in an embodiment.

[0043] Figure 1b It is a structural block diagram of a DPF system with a TI device in an embodiment.

[0044] Figure 1c It is a structural block diagram of a DPF system with a TI device in an embodiment.

[0045] Figure 1d It is a structural block diagram of a DPF system with a TI device in an embodiment.

[0046] Figure 2a It is a cross-sectional structure diagram of the spray point module.

[0047] Figure 2b It is a structural diagram of the delivery pipe and nozzle of the fuel injection device.

[0048] Figure 2c It is a cross-sectional schematic diagram of the fresh air injector.

[0049] Figure 3a It is a structural block diagram of the Tb closed-loop control.

[0050] Figure 3b It is a structural block diagram of the Td closed-loop control.

[0051] Figure 4aIt is a flowchart of a TI control program.

[0052] Figure 4b It is a flowchart of an aerator control subroutine. Specific embodiments

[0053] In order to regenerate the DPF in low-temperature exhaust gas and to reduce the cost of the DOC, an object of the present invention is to provide a thermal energy injection TI (Thermal Injector) device. This device uses an oxidation catalyst with a coating amount of precious metal as low as possible to heat the exhaust gas with a temperature lower than the light-off temperature of the DOC, thereby expanding the opportunity for DPF regeneration of the system at the lowest cost and reducing the problem of excessive soot loading caused by untimely regeneration.

[0054] Another object of the present invention is to oxidize fuel with oxygen in the exhaust gas as much as possible, and to supplement oxygen when oxygen is insufficient, so that the system can complete DPF regeneration with the lowest fuel consumption.

[0055] The third object of the present invention is to reduce the heat flow temperature after fuel oxidation heating as much as possible, thereby reducing the cost of the exhaust pipe.

[0056] The fourth object of the present invention is to use a system integrating DOC and DPF, thereby reducing the complexity of the system.

[0057] The fifth object of the present invention is to provide a control method for controlling the TI device in the present invention.

[0058] The present invention proposes a DPF system with a thermal energy injection device (TI device). The TI device includes an inlet manifold, an outlet manifold, and upper and lower branches connected to these two manifolds. The flow ratio of the upper and lower branches is adjusted by a flow control valve. An upstream burner device, an oxidation catalyst, a downstream fuel injection device, and a flame holder are arranged in the lower branch. After the DPF regeneration is triggered, when the oxygen concentration is sufficient, first the upstream fuel injection device injects fuel, and the fuel oxidizes and releases heat after being heated to the light-off temperature, so that the gas flow temperature reaches the hot surface combustion temperature of the fuel (such as 550 degrees Celsius). Then the downstream fuel injection device injects fuel, and the fuel burns in the flame holder, forming a flame and a heat flow. The heat flow is mixed with the exhaust gas passing through the upper branch in the outlet manifold and then enters the downstream DPF. In another embodiment of the present invention, a fresh air injection device (aerator) is also arranged in the lower branch. When the oxygen concentration is insufficient, fresh air is injected into the lower branch through the aerator to enhance the fuel oxidation condition and increase the fuel injection amount.

[0059] In the above TI device, fuel generates heat flow and flame in the exhaust gas through two-stage oxidation. Compared with an external burner that only uses fresh air, the TI device only needs to supplement fresh air when the oxygen is insufficient, which results in a low fresh air flow rate and less energy consumption to reach the same regeneration temperature. Compared with an internal burner that only uses exhaust gas, the TI device can supplement fresh air when necessary, reducing the risk of hydrocarbon and carbon monoxide leakage. In the TI device, fuel only burns in the lower branch. Therefore, compared with a full-flow device, the total noble metal coating amount of the catalyst is greatly reduced. (In the TI device of the above technical solution, fuel only passes through the lower branch. Ideally, if the fuel burns sufficiently during DPF regeneration, the downstream DPF can be without noble metal coating. However, to enhance the regeneration effect, increase the generation of NO2, and oxidize unburned fuel, the downstream DPF needs to have a certain amount of noble metal coating, but there is no need for an additional DOC to oxidize the fuel. Therefore, the total noble metal coating amount can be greatly reduced.)

[0060] The above TI device requires two fuel injection devices. The upstream fuel injection device and the DOC in the lower branch together generate a high-temperature heat flow (limited by the maximum temperature of the DOC, this heat flow temperature cannot be too high - generally not exceeding 600 degrees Celsius, nor can it alone make the mixed gas reach or exceed the regeneration temperature of the DPF). The fuel injected by the downstream fuel injection device burns in the heat flow, releasing heat and further heating the exhaust gas, so that the temperature of the mixed exhaust gas reaches the regeneration temperature. Limited by the maximum temperature resistance of the exhaust pipe and the oxygen content in the lower branch, the split ratio between the upper branch and the lower branch cannot be too large (otherwise the lower branch will overheat, or the oxygen content will be insufficient due to excessive fuel injection). In another embodiment of the present invention, in order to reduce the requirement for the temperature resistance of the pipeline, the downstream fuel injection device is arranged in the upper circuit. The heat flow provided by the lower circuit during regeneration heats the exhaust gas in the upper circuit so that the temperature of the mixed exhaust gas reaches the ignition temperature of the downstream main DOC, and then the fuel injected in the upper circuit oxidizes and releases heat in the DOC, thereby making the temperature of the exhaust gas flowing through the DPF reach its regeneration temperature. Since the oxidation and heat release of fuel are mainly completed in the DOC, the system in this embodiment has a lower requirement for the temperature resistance of the exhaust pipe.

[0061] In another embodiment of the present invention, the catalyst of the downstream main DOC is coated on the DPF carrier, and the DOC and the DPF are combined into one module (DOC on DPF). Compared with the structure where the DOC and the DPF are separated, the DOC on DPF structure is compact, but the hydrocarbon conversion efficiency is relatively low. Therefore, compared with the system in the above text, the mixed exhaust gas of the upper and lower branches needs to have a higher temperature.

[0062] The exhaust gas temperature is controlled by a program running in the controller. The present invention also proposes a control method for a DPF system with a heat energy injection device for controlling the above system. This method uses two-stage PID control to closed-loop control the exhaust gas temperature flowing through the DPF, and oxygenates or alarms the exhaust gas when the oxygen concentration is insufficient.

[0063] Embodiment:

[0064] An embodiment of the present invention is as Figure 1a shown. In this system, the TI device includes an inlet manifold 102, an upper branch 111 and a lower branch 112 connected thereto, and an outlet manifold 103 after the upper and lower branches converge. There is a flow regulating device 134 in the upper branch 111 for regulating the flow ratio between the upstream and downstream flow paths. In the lower branch 112, a spraying point module 108, a pre-small DOC catalyst 135, a fuel injection device 109, and a flame holder 110 are arranged in sequence from upstream to downstream. On the inlet manifold 102, there is a temperature sensor 136 for measuring the exhaust gas temperature Tu entering the manifold, and between the small DOC catalyst 135 and the flame holder 110, a temperature sensor 132 is arranged. The sensors 136 and 132 are respectively connected to the controller 140 through signal lines 124 and 127. The fuel supply of the spraying point module 108 is controlled by a fuel flow control valve 106, and this control valve is connected to the controller 140 through a signal line 122. In the spraying point module 108, there is also an electrothermal unit connected to the controller 140 through a signal line 123. The fuel of the fuel injection device 109 is controlled by another fuel flow control valve 107, and this control valve is connected to the controller 140 through a signal line 125. The outlet manifold of the TI is connected to the downstream DPF 145. The pressure difference across the DPF and the pressure downstream of the DPF are measured by a pressure and relative pressure sensor (dP&P) 137, and the measured value of this sensor is reported to the controller 140 through a signal line 126. Finally, downstream of the DPF 145, there is also a temperature sensor 138, and this sensor is connected to the controller 140 through a signal line 128.

[0065] Figure 1a The working principle of the TI shown can be illustrated by the following example:

[0066] First, adjust the flow regulating valve 134 of the upper branch to make the flow rate ratio of the upper and lower branches 1:1. Under a certain working condition, the tail gas mass flow rate is 80 g / s and the tail gas temperature is 150 °C. At this time, energize the solenoid valve 106, and the fuel enters the injection point module 108 and is ignited therein. Control the solenoid valve 106 to make the fuel flow rate reach 0.41 g / s, and turn on the closed-loop temperature control of Tb to make the Tb temperature reach 600 °C. Then energize the solenoid valve 107, and the fuel is injected into the downstream of the lower branch through the device 109. Control the solenoid valve 106 to make the fuel flow rate reach 0.33 g / s, and turn on the closed-loop temperature control of Td to make the heat flow temperature of the lower branch reach nearly 950 °C. After the air flow in the lower branch is mixed with that in the upper branch, the temperature reaches nearly 550 °C, and the downstream DPF is regenerated.

[0067] In Figure 1a 's system, the function of the injection point module 108 is to control the fuel injection rate and ignite the injected fuel under certain conditions. There are various structures to implement this injection point module, and an embodiment is as Figure 2a shown. In this embodiment, the injection point module 108 includes a housing 212 with an opening 211 at its upstream end, through which air can enter the interior of the housing. An electric heating unit is installed in the housing, and the unit includes a housing 105, a glow plug 204, and a spiral vane 203. When the fuel flow control valve 106 is powered on and opened, the fuel enters the housing 105 through the opening 201 and contacts the glow plug 204. The glow plug 204 has an electrode 202 connected to the controller 140 through a signal line 123 ( Figure 1a ). After the glow plug 204 is powered on, the fuel in contact with it is heated, and then rises through the passage formed by the spiral vane 203 and the outer surfaces of the housing 105 and the glow plug, and is then ejected through the opening 207. Downstream of the electric heating unit is a flame holder 210, and the fuel ejected through the nozzle 207 is mixed with air and burned in the flame holder. The heat flow generated by the fuel combustion flows out through the outlet 213.

[0068] Figure 1a The function of the downstream fuel injection device 109 in the system is to atomize and inject fuel. An embodiment of this injection device is as Figure 2b shown. The fuel injection device in the figure includes an inlet joint 304, a fuel delivery pipe 305, and an atomizing nozzle 306 connected to the end of the delivery pipe. In Figure 1a 's system, after the fuel flow control valve 107 is powered on and opened, the fuel enters the atomizing nozzle 306 through the inlet joint 304 and the fuel delivery pipe 305, and then the fuel atomized into small droplets is ejected from the nozzle 306 and mixed with air and burned in the flame holder 110.

[0069] Figure 1aIn the system shown, the exothermic oxidation of fuel only occurs in the lower branch 112. If the oxygen content in the exhaust gas is insufficient, it will cause incomplete oxidation of the fuel. To avoid excessive fuel injection, it is necessary to calculate and limit the maximum fuel injection amount. The limit of the maximum fuel injection amount mf_max112 can be calculated using the following formula:

[0070] mf_max112 = K0 * ma * (1 - 1 / λ) / λ0(F1)

[0071] Where K0 is a constant determined by the split ratio of the upper and lower branches, ma is the mass flow rate of the engine intake air; λ0 is the stoichiometric air-fuel ratio, which can be taken as a constant 14.6; λ is the excess air coefficient provided by the engine ECU (or measured by an oxygen sensor or NOx sensor (not shown) in the exhaust pipe).

[0072] To increase the fuel injection amount under the condition of low oxygen content in the exhaust gas, it is necessary to increase the oxygen content in the lower branch. As Figure 1b shown (an oxygen enricher is provided in this TI device), in another embodiment of the present invention, an intake air injector (oxygen enricher) 131 is arranged upstream of the injection point module 108 of the lower branch 112, and is connected to an air source through a pipeline 133 and a fresh air flow control valve 105 (the fresh air can be supplied by an air pump or a compressed air tank). The electrical part of this control valve is connected to the controller 140 through a signal line 121. The temperature of the fresh air is generally much lower than that of the exhaust gas. To save the fuel consumption for heating the fresh air, the pipeline can be placed in the exhaust gas to preheat the fresh air using the exhaust gas heat. In Figure 1b the system, a part of the pipeline 133 is placed in the exhaust pipe 101, and this exhaust pipe is connected to the exhaust gas inlet manifold 102.

[0073] An embodiment of the intake air injector 131 is as Figure 2c shown. This injector includes an inlet joint 301, a check valve 302, and an injection pipe 303 downstream thereof. In Figure 1b the system, when the air flow control valve 105 is powered on and opened, the fresh air enters the lower branch 112 through the heating pipeline 133, the inlet joint 301, the check valve 302, and the injection pipe 303. After the control valve 105 is powered off and closed, the check valve 302 closes under the exhaust gas pressure in the lower branch to prevent the exhaust gas from flowing back into the air source.

[0074] Limited by the maximum heating power, if the exhaust gas flow rate is high, then upstream fuel injection and closed-loop temperature control of Tb need to be carried out under the condition of a higher exhaust gas temperature. A high exhaust gas temperature poses high temperature resistance requirements on the materials, increasing the cost of the system. To reduce the exhaust gas temperature in the exhaust pipe, a downstream oxidation catalyst can be used to complete the main fuel oxidation. As Figure 1cAs shown, in this embodiment, the upper branch 311 and the lower branch 312 are connected to the inlet manifold 102. A flow regulating valve 334 is arranged in the upper branch 311, and a fuel injection device 309 is arranged downstream thereof. The fuel flowing through the injection device is controlled by a fuel flow control valve 307. And Figure 1a the same injection point module 108 in the system is arranged in the lower branch 312, and the fuel flow supplied to the injection point module is controlled by a fuel flow control valve 106. A small DOC 335 is arranged downstream of the injection point module 108. The upper and lower branches 311 and 312 converge at the outlet manifold 303, where a mixer 310 is installed, and a main DOC 346 and a DPF 345 are arranged downstream thereof. And Figure 1a the same exhaust gas temperature sensors 136, 132, and 138 in the system are respectively used to detect the exhaust gas temperature at the inlet manifold, downstream of the small DOC 335, and downstream of the DPF 345. The pressure difference across the DPF 345 and the pressure downstream thereof can also be detected by the same pressure difference and pressure sensor 137. The same controller 140 is connected to the sensors 136, 132, 137, and 138 through signal lines 124, 125, 126, and 128 respectively, controls the fuel flow control valve 106 through the signal line 122, controls the glow plug of the injection point module 108 through the signal line 123, and controls the fuel flow control valve 307 through the signal line 327. The fuel injection device 309 can adopt the same structure as the device 109.

[0075] Figure 1c In the system (this system includes a downstream main DOC, and the downstream burner of TI is arranged in its upper branch), since the fuel ejected by the fuel injection device 309 oxidizes and releases heat in the main DOC 346, rather than burning in the heat flow, it is not necessary for the lower branch 312 to generate a high-temperature heat flow exceeding the fuel ignition temperature. In the lower branch 312, the functions of the injection point module 108 and the small DOC 335 are to heat the exhaust gas in the lower branch, so that the exhaust gas temperature after mixing with the exhaust gas in the upper branch rises above the ignition temperature of the main DOC 346 (under the action of the catalyst, this ignition temperature is much lower than the ignition temperature of the fuel in the flame holder). Since the exhaust gas temperature after heating has a large increase, the requirement for the noble metal coating amount of the main DOC 346 can be reduced, and the comprehensive cost of the main DOC 346 and the small DOC 335 can be reduced. After the exhaust gas temperature passing through the mixer 310 exceeds the ignition temperature of the main DOC 346, the fuel flow control valve 307 can be opened, and fuel is injected through the fuel injection device 309 in the upper branch. The fuel injected in this part oxidizes and releases heat in the main DOC 346, so that the exhaust gas temperature in the DPF 345 reaches the regeneration temperature of the DPF. Figure 1cIn the system, the function of the lower-branch heat flow is to heat the upper-branch gas flow so that the temperature of the mixed exhaust gas reaches the ignition temperature of the main DOC. The fuel injected into the upper branch ignites in the DOC rather than in the pipeline (such as Figure 1a and 1b in the lower branch of the system). Therefore, there is no need to perform special high-temperature resistance treatment on the exhaust pipeline, and the fuel injection rate of the upper branch can thus be higher (not limited by the high temperature resistance of the exhaust pipeline).

[0076] Figure 1c In the system, the main DOC and DPF can also be combined and adopt an independent module structure. As Figure 1d shown (DOConDPF is used in this system), in such a system, the DPF 348 independent module includes a DOC sub-module 346 and a DPF sub-module 347. In one embodiment, both the DOC sub-module 346 and the DPF sub-module 347 are noble metal partition coating parts (DOConDPF) coated on the DPF carrier. The noble metal coating amount of the DOC sub-module 346 is larger than that of the DPF sub-module 347, with higher hydrocarbon conversion efficiency and lower fuel ignition temperature.

[0077] In Figure 1a the system, the controller can control the system to operate in two heating modes: exhaust gas thermal management mode and DPF regeneration mode. In the exhaust gas thermal management mode, part of the exhaust gas is heated by the lower branch and then mixed with the exhaust gas flowing through the upper branch. The heated exhaust gas flows through the DPF and enters the downstream exhaust gas treatment device (not shown). The downstream exhaust gas treatment device can include an SCR system, which requires an appropriate operating temperature to achieve the required denitrification efficiency. In the exhaust gas thermal management mode, the downstream fuel injection device 109 can stop fuel injection, and the exhaust gas is completely heated by the heat flow generated by the injection point module 108 and the small DOC 135. The exhaust gas thermal management mode can be used to quickly warm up the exhaust gas during engine cold start. Since external hydrocarbon (fuel) injection is used, a relatively large heating power can be obtained, and problems such as near-post injection work or far-post injection oil dilution caused by in-cylinder injection can be avoided.

[0078] In the DPF regeneration mode, first, a high-temperature heat flow is generated by the injection point module 108 and the small DOC 135. Then, under its action, the fuel injected by the fuel injection device 109 burns in the flame holder 110, further increasing the heat flow temperature, so that the mixed heat flow reaches the DPF regeneration temperature in the DPF. The fuel injection device 109 and the injection point module 108 upstream of it actually form two burners in series. The upstream burner (including the fuel injection device 109 and the small DOC 135) provides a heat flow that does not exceed the maximum temperature tolerated by the DOC catalyst and has no hydrocarbon leakage, while the downstream burner (including the fuel injection device 109) injects fuel to further burn in this heat flow, raising the exhaust gas temperature in the lower branch 112. Under the high-temperature action of the heat flow, the downstream burner can burn fully under the condition of rapid change of the air flow rate, so very little unburned matter is generated, and it can be fully treated under the action of the catalyst in the DPF without causing emission problems.

[0079] In one embodiment, a control method for a DPF system with a heat energy injection device, that is Figures 1a - 1d The system in can be controlled by the controller 140 by running the computer program therein. There are two levels of temperature control in the system: the first level is to control the downstream temperature of the small DOC 135 in the branch 112, and the second level is the downstream temperature of the DPF 145. Both levels of temperature can be controlled in a closed loop. The first-level closed-loop control can use a structure as shown in Figure 3a . As shown in the figure, first, determine the downstream target temperature Tc of the small DOC 135. In the DPF regeneration mode, Tc needs to exceed the ignition temperature of the fuel in the flame holder 110 (such as 550 degrees Celsius). In both the DPF regeneration mode and the exhaust gas thermal management mode, Tc cannot exceed the maximum temperature tolerated by the small DOC 135 catalyst. After determining Tc, the feedforward fuel injection rate, mf1, can be calculated using the following formula:

[0080] mf1 = K1 * (Tc - Tu) * me / LHV(F2)

[0081] where K1 is a constant determined by the isobaric heat capacity of the exhaust gas and the air flow rate ratio of the upper and lower branches, Tu is the exhaust gas temperature in the intake manifold measured by the sensor 136, me is the exhaust gas mass flow rate, LHV is the low calorific value constant, and for diesel, it can be taken as 43 kJ / g. Figure 3a In the feedback loop in, Tc is compared with the temperature Tb measured by the sensor 132, and the difference is used to calculate the feedback correction value mb1 through the PID controller. Finally, the closed-loop fuel control command mc1 is obtained by adding the feedforward injection rate mf1 and the feedback correction value mb1. This command is used to control the opening duty ratio of the fuel flow control valve 106 (using the PWM method to control the flow rate), thereby controlling the fuel flow rate entering the injection point module 108. The second-level closed-loop control can adoptFigure 3b The structure shown. In this control structure, Tg is the target temperature downstream of the DPF 145. In the exhaust gas thermal management mode, if the Tc value is lower than the ignition temperature of the fuel in the flame holder 110, the second-stage closed-loop control is not required. Otherwise, Tg can be set to the effective operating temperature of the downstream SCR (not shown) (such as 250 degrees Celsius). In the DPF regeneration mode, Tg is set to the regeneration temperature of the DPF 145 (such as 530 degrees Celsius). According to the Tg value, the feedforward injection amount mf is calculated by the following formula:

[0082] mf = K * (Tg - Tu) * me / LHV(F3)

[0083] where K is a constant determined by the isobaric heat capacity of the exhaust gas. In the feedback loop, first, Tg is compared with the temperature Td measured by the sensor 138, and the error value Err is calculated by the PID controller to obtain the feedback command mb, and then the injection command mc2 is calculated from mb, mf, and mc1:

[0084] mc2 = mf + mb – mc1(F4)

[0085] If the fuel flow control valve 107 or 307 uses PWM control, mc2 is used to control the duty cycle of the PWM, thereby controlling the fuel flow through the fuel injection device 109. Limited by the oxygen content in the exhaust gas, the sum of the fuel injection commands mc1 and mc2 cannot exceed the total injection amount mf_max,

[0086] mf_max = ma * (1 - 1 / λ) / λ0(F5)

[0087] In one embodiment, a control method for a DPF system with a thermal energy injection device, that is Figures 1a - 1d the control method of the system shown can be implemented by a control program running in the controller 140. A flowchart of an embodiment of this control program is as Figure 4a shown. After the program starts, first, it is determined whether the system is in the regeneration or thermal management mode. If it is not in or has exited these two modes, the program stops. Otherwise, the values of mf_max112 and mf1 are calculated according to the formulas F1 and F2 respectively, and mc1 is calculated according to the Figure 3a shown closed-loop control. Then, the values of mf_max and mf are calculated according to the formulas F5 and F3, and Figure 3bThe closed-loop control and F4 calculation mc2 shown. After calculating mc1, mc2, mf_max112, and mf_max, compare the sum of mc1 and mf_max112 and the sum of mc1 and mc2 with mf_max. If mc1 is less than mf_max and mc1 + mc2 is less than mf_max, set the control command of the fuel flow control valve 106 to mc1, and then determine whether the temperature Tb is less than the threshold ThdTl1 for too long or greater than the threshold ThdTh1 for too long. If it is too long, reset the control commands of the flow control valves 106 and 107 to 0, then report an error and stop. Otherwise, the program sets the control command of the fuel flow control valve 107 to mc2, and then determines whether the temperature Td is less than the threshold ThdTl2 for too long or greater than the threshold ThdTh2 for too long. If it is too long, reset the control commands of the flow control valves 106 and 107 to 0, and stop after reporting an error. Otherwise, the program returns to determine whether to start DPF regeneration or the thermal management mode. In the step of comparing the value of mc1 and mf_max112 and the value of mc1 + mc2 with mf_max, if mc1 is greater than mf_max112 or mc1 + mc2 is greater than mf_max, start fresh air treatment in step 390, and then determine whether an error occurs in this step. If no error occurs, the program returns to the comparison step. Otherwise, the program resets the control commands of the flow control valves 106 and 107 to 0 and stops after reporting an error.

[0088] Step 390 can be a subroutine, and the flowchart of its embodiment is as Figure 4b shown. After this subroutine starts, first determine whether there is a flow control valve 105. If it exists, power on and open the air flow valve 105. Then determine whether the time when mc1 exceeds mf_max112 or mc1 + mc2 exceeds mf_max is too long. If it is too long, stop and exit after reporting an error.

[0089] In a specific implementation, the present application provides a computer storage medium and a corresponding data processing unit. Among them, the computer storage medium can store a computer program, and when the computer program is executed by the data processing unit, it can run the content of the invention of a DPF system with a heat energy injection device and its control method provided by the present invention and some or all of the steps in each embodiment. The storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM), etc.

[0090] Those skilled in the art can clearly understand that the technical solutions in the embodiments of the present invention can be implemented by means of a computer program and its corresponding general hardware platform. Based on such an understanding, the essence of the technical solutions in the embodiments of the present invention, or the part that contributes to the prior art, can be embodied in the form of a computer program, that is, a software product. This computer program software product can be stored in a storage medium and includes several instructions for causing a device (which can be a personal computer, a server, a single-chip microcomputer, a MUU or a network device, etc.) including a data processing unit to execute the methods described in various embodiments or some parts of the embodiments of the present invention.

[0091] The present invention provides an idea and method for a DPF system with a heat energy injection device and its control method. There are many methods and ways to specifically implement this technical solution. The above description is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and retouches can be made, and these improvements and retouches should also be regarded as the protection scope of the present invention. Each component not clearly defined in this embodiment can be implemented by the prior art.

Claims

1. A DPF system with a thermal energy injection device, characterized in that, Comprising: A controller (140) for controlling the system, a DPF device, and a thermal energy injection device provided upstream thereof, wherein the thermal energy injection device includes: an inlet manifold (102) with one end for receiving exhaust gas, the other end of the inlet manifold (102) is connected to a first branch and a second branch, the other ends of the first branch and the second branch are connected to one end of an outlet manifold, and the other end of the outlet manifold is connected to a downstream DPF device and transmits the exhaust gas processed by the thermal energy injection device to the downstream DPF device; A flow control valve for regulating the flow ratio in the first branch and the second branch; a spraying point module (108) for generating a high-temperature heat flow and a pre-stage small DOC catalyst (135) are provided in the second branch; wherein, the fuel injection amount of the spraying point module (108) is controlled by a first fuel flow control valve (106); In the thermal energy injection device, further included is: a downstream fuel injection device provided in the first branch or the second branch; wherein, the fuel injection amount of the downstream fuel injection device is controlled by a second fuel flow control valve (107); When the downstream fuel injection device, i.e., the fuel injection device, is provided in the second branch, it is located downstream of the pre-stage small DOC catalyst (135); When the downstream fuel injection device, i.e., the fuel injection device, is provided in the first branch, it is located downstream of the flow control valve.

2. The DPF system with a thermal energy injection device according to claim 1, characterized in that When the downstream fuel injection device, i.e., the fuel injection device, is provided in the second branch, it is located downstream of the pre-stage small DOC catalyst (135), and a flame holder is provided downstream thereof.

3. The DPF system with a heat energy injection device according to claim 1, characterized in that, When the downstream fuel injection device, i.e., the fuel injection device, is provided in the first branch, it is located downstream of the flow control valve, a mixer (310) is provided in the outlet manifold, and the exhaust gas flow flowing out of the first branch and the exhaust gas flow flowing out of the second branch are uniformly mixed in the mixer (310).

4. A DPF system with a thermal energy injection device according to claim 1, wherein, In the thermal energy injection device, further included is: an oxygenator (131) provided upstream of the spraying point module (108) in the second branch for injecting fresh air into the second branch.

5. The DPF system with a heat energy injection device according to claim 4, wherein The oxygenator (131) is connected to an air source through a pipeline (133) and a fresh air flow control valve (105).

6. The DPF system with a heat energy injection device according to claim 1, wherein The spraying point module (108) is used for injecting fuel and igniting the injected fuel to generate a high-temperature heat flow, and includes: an air flow inlet hole (211), a fuel inflow channel, an electro-thermal unit, and a flame holder.

7. The DPF system with a thermal energy injection device according to claim 1, wherein, The downstream fuel injection device is used for atomizing and injecting fuel, and includes: a fuel delivery pipe (305) for delivering fuel, and an atomizing nozzle (306) for spraying the atomized fuel.

8. A DPF system with a heat energy injection device according to claim 3, characterized in that, In the DPF device, included are: a DOC sub-module (346) and a DPF sub-module (347); Wherein, the DOC sub-module (346) and the DPF sub-module (347) are independently provided, or the DOC sub-module (346) and the DPF sub-module (347) are provided by partitioning and coating noble metals on the carrier of the DPF, i.e., adopting the DOConDPF method.

9. A control method for a DPF system with a thermal energy injection device, used to control any of the systems in claims 1-8, characterized in that, Including the following steps: Step 1, in the DPF system having a thermal energy injection device, set sensors to collect required data: Step 2, determine whether the system is in the DPF regeneration or thermal management mode. If so, execute Step 3; otherwise, directly stop the control. Step 3, calculate the maximum fuel injection quantity limit mf_max112 and the fuel control command mc1 for controlling the first fuel flow control valve (106) according to the values obtained by the sensor. Calculate the total injection quantity mf_max and the fuel control command mc2 for controlling the second fuel flow control valve (107). Step 4, determine whether the following conditions are met, namely: mc1>mf_max112 or mc1+mc2>mf_max If met, enter Step 5; otherwise, enter Step 6. Step 5, perform fresh air treatment, and determine whether there is an error. If not, return to Step 4; otherwise, enter Step 7. Step 6, set the control command of the first fuel flow control valve (106) in the system to the fuel control command mc1, and determine whether the time when the temperature Tb downstream of the pre-stage small DOC catalyst (135) in the system is less than the first threshold ThdTl1 or greater than the second threshold ThdTh1 exceeds the preset duration. If so, enter Step 7; otherwise, enter Step 8. Step 7, reset the control commands of the first fuel flow control valve (106) and the second fuel flow control valve (107) to 0, then report an error and stop the control. Step 8, set the control command of the second fuel flow control valve (107) to the post-injection command mc2, and determine whether the time when the temperature Td at the most downstream of the system, i.e., downstream of the DPF device in the system, is less than the third threshold ThdTl2 or greater than the fourth threshold ThdTh2 exceeds the preset duration. If so, enter Step 7; otherwise, return to execute Step 2.

10. The control method of a DPF system with a heat energy injection device according to claim 9, characterized in that, The fresh air treatment described in Step 5 specifically includes the following steps: Step 5-1, determine whether there is a fresh air flow control valve (105) in the system. If so, enter Step 5-2; otherwise, enter Step 5-3. Step 5-2, open the fresh air flow control valve (105), and enter Step 5-3. Step 5-3, determine whether the following conditions are met: Whether the duration of mc1>mf_max112 or mc1+mc2>mf_max is greater than the preset duration. If so, report an error and stop the control; otherwise, directly stop the control.

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