Control device and control method for national 7 diesel engine with low emission and low oil consumption

Abstract

The invention discloses a low-emission and low-oil-consumption control method for a national seven diesel engine, which relates to an engine control technology and comprises the following steps: acquiring the running state and the post-processing regeneration state of a vehicle, and determining the running mode of a 48V system of the vehicle according to the running state and the post-processing regeneration state; the operation modes comprise a charging mode, a power assisting mode, a reheating mode and a light heating mode; when it is detected that the vehicle is in a DPF running regeneration state and the SOC of the power battery is larger than or equal to the minimum threshold a1, a 48V system of the vehicle enters a reheating mode; and when the SOC of the power battery is larger than or equal to the minimum threshold a1 and the temperature T6 at the outlet of the DPF is smaller than a set first temperature threshold, the 48V system of the vehicle enters a light heating mode. The invention further discloses a control device of the national seventh diesel engine with low emission and low oil consumption. According to the invention, the dynamic property of the vehicle is improved, the energy consumption is reduced, the problem of low SCR conversion efficiency under a low-temperature environment and a small-load working condition is solved, and ultralow NOx emission is realized.

Description

Technical Field

[0001] The present invention relates to engine control technology, and more specifically, to a low-emission and low-fuel-consumption National VII diesel engine control device and control method. Background Art

[0002] With the development of internal combustion engine technology, diesel engines are one of the indispensable power sources due to their mature industrial chain, high efficiency and high power density. However, with the further tightening of fuel consumption and emission regulations, the difficulty of coordinated control between fuel consumption and emissions has gradually increased. Since the engine operating conditions of vehicles are relatively dispersed during actual operation, in order to achieve low fuel consumption under all operating conditions, the complexity of the engine structure increases and the control difficulty increases. Moreover, with the reduction of fuel consumption and the increase of useful output work, the exhaust energy will decrease. The reduction of exhaust energy will lead to insufficient exhaust temperature, and it will be difficult for the SCR in the after-treatment system to quickly reach and maintain a suitable operating temperature. Therefore, the further reduction of fuel consumption brings greater challenges to the currently mainstream SCR exhaust treatment technology. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a low-emission and low-fuel-consumption National VII diesel engine control device and control method in view of the deficiencies in the prior art, which has the advantages of low fuel consumption, low emissions and high safety.

[0004] The present invention discloses a low-emission and low-fuel-consumption National VII diesel engine control method, which comprises: collecting the operating state and post-processing regeneration state of the vehicle, and determining the operating mode of the vehicle's 48V system according to the operating state and post-processing state; the operating mode includes:

[0005] Charging mode: When the SOC of the power battery of the 48V system of the vehicle is less than the set minimum threshold a1, the 48V system of the vehicle enters the charging mode;

[0006] Power-assist mode: When the vehicle is in an accelerating state and the power battery SOC is greater than or equal to a minimum threshold a1, the vehicle's 48V system enters the power-assist mode;

[0007] Reheating mode: when it is detected that the vehicle is in DPF driving regeneration and the power battery SOC is greater than or equal to the minimum threshold a1, the vehicle's 48V system enters the reheating mode;

[0008] Light heating mode: When the power battery SOC is greater than or equal to the minimum threshold a1, and the temperature T6 at the DPF outlet is less than the set first temperature threshold, the vehicle's 48V system enters the light heating mode.

[0009] As a further improvement, the reheating mode is: the power battery provides electrical energy to the EHC of the post-processing system, so that the EHC enters a set high-power state to quickly increase the DOC front exhaust temperature T4 to a set target temperature threshold.

[0010] Furthermore, during the reheating mode, if the power battery SOC is less than the minimum threshold a1, the 48V system is controlled to enter the charging mode, the power battery is stopped from outputting electrical energy, and the power battery is charged. At the same time, the EHC is powered by the generator of the 48V system to ensure that the EHC still operates in the set high power state.

[0011] Further, when the DOC front exhaust temperature T4 is greater than or equal to a set second temperature threshold, the reheating mode is exited.

[0012] As a further improvement, the light heating mode is: the power battery provides electrical energy to the EHC of the post-treatment system so that the temperature T6 at the DPF outlet is equal to or greater than the first temperature threshold, and the temperature T6 at the DPF outlet is maintained at a minimum at the first temperature threshold.

[0013] As a further improvement, when the vehicle is running in a cold environment or the vehicle speed and load are both less than the set corresponding thresholds or the exhaust temperature is lower than the set exhaust temperature threshold, the light heating mode is triggered.

[0014] As a further improvement, when the temperature T6 at the DPF outlet is greater than or equal to a third temperature threshold, the light heating mode is exited.

[0015] As a further improvement, the power-assisting mode is as follows: the power battery discharges the flywheel motor, and the flywheel motor assists the engine in doing work to increase power output, so that the vehicle speed is quickly increased to the target value.

[0016] A low-emission and low-fuel-consumption National VII diesel engine control device, comprising an ECU, a 48V system and a post-processing system; the 48V system comprises a generator, a controller and a power battery, and the post-processing system comprises an EHC, a DOC, a DPF and an SCR; a first power supply line is provided between the generator and the EHC, a second power supply line is provided between the power battery and the EHC, a linkage relay is provided on the first power supply line and the second power supply line, and a DC-DC driver is provided on the second power supply line; the ECU applies the control method as described in any one of claims 1 to 8 to control the operation of the 48V system.

[0017] Beneficial Effects

[0018] The advantages of the present invention are:

[0019] 1. The 48V system realizes energy recovery and braking functions, fully absorbing the kinetic energy of the engine deceleration process, while increasing braking power and improving driving safety.

[0020] 2. The 48V system optimizes the engine operating conditions. According to the battery SOC level, the operating point is adjusted through driving power generation and parking power generation, so that the engine operating area is in the high-efficiency area. At the same time, during the acceleration process, the motor is used to provide assistance to improve the vehicle's power and reduce energy consumption.

[0021] 3. The 48V system realizes the temperature management of post-processing, provides energy support to EHC through the power battery, increases the inlet temperature of SCR, improves the low conversion efficiency of SCR in low temperature environment and small load conditions, and achieves ultra-low NOx emissions.

[0022] 4. The 48V system realizes the temperature management of post-processing, provides energy support to EHC through the power battery, and improves the regeneration efficiency of DPF through EHC's temperature management of post-processing DPF, reduces the use of post-injection, and reduces the fuel consumption of regeneration conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic flow chart of the control method of the present invention;

[0024] Figure 2 It is a schematic diagram of the structure of the control device of the present invention. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the embodiments, but it does not constitute any limitation to the present invention. Any limited number of modifications made by anyone within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0026] See also Figure 1 The present invention provides a low-emission and low-fuel-consumption National VII diesel engine control method, the control method comprising: collecting the operating state and post-processing regeneration state of the vehicle, and determining the operating mode of the vehicle's 48V system according to the operating state and post-processing state. In this embodiment, the operating modes of the 48V system include a charging mode, a power-assisting mode, a heavy heating mode, and a light heating mode.

[0027] Charging mode: ECU determines whether the vehicle is decelerating based on the speed change rate and brake signal. If the vehicle is decelerating, the 48V system enters the charging mode, the engine drives the generator to charge the power battery, and at the same time increases the engine's accessory power to assist the vehicle in decelerating. When the power battery SOC> the maximum threshold a2 (the maximum threshold, 70% in this embodiment), the charging mode stops. When it is detected that the vehicle speed is 0 and the gear is in neutral, the current power battery SOC value is determined. When the power battery SOC<the minimum threshold a1, parking power generation is turned on. That is, it is best to keep the power battery SOC value between a1 and a2 when the vehicle is stopped.

[0028] Assist mode: When the ECU determines that the vehicle is in acceleration state and the power battery SOC is greater than or equal to the minimum threshold a1, the vehicle's 48V system enters the assist mode. At this time, the power battery discharges the flywheel motor, and the flywheel motor assists the engine to increase power output, so that the vehicle speed can be quickly increased to the target value. The assist mode can increase the acceleration power of the engine, reduce acceleration time, and reduce fuel consumption.

[0029] Reheating mode: When it is detected that the vehicle is in DPF driving regeneration and the power battery SOC is greater than or equal to the minimum threshold a1, the vehicle's 48V system enters the reheating mode. Specifically, the power battery provides power to the EHC of the post-processing system, so that the EHC enters the set high-power state to quickly increase the DOC front row temperature T4 to the set target temperature threshold. The target temperature threshold of this embodiment can be 260°C; in addition, the high-power state of the EHC is the heating power required to achieve the rapid heating of the DOC front row temperature T4, and the heating power of the EHC is dynamically adjusted, the purpose is to make the temperature increase a relatively stable fluctuation, so as to prevent excessive temperature rise. In this embodiment, the high-power state of the EHC can be understood as 80% of the rated power output of the DC-DC driver to the rated power. . However, during the reheating mode, if the power battery SOC is less than the minimum threshold a1, the 48V system is controlled to enter the charging mode, stop the power battery from outputting power, and charge the power battery. At the same time, the generator of the 48V system is used to power the EHC to ensure that the EHC still works in the set high-power state. That is, the original power battery power supply is switched to direct power supply from the generator, which ensures that the DOC front exhaust temperature T4 can still be quickly increased while avoiding excessive discharge of the power battery. The switching between power battery power supply and generator power supply can be achieved through a linkage relay installed on the power supply line connecting the two and the EHC.

[0030] When the DOC front exhaust temperature T4 rises above the target temperature threshold, the DPF driving regeneration strategy will release the engine's remote post-injection, and the fuel of the remote post-injection will be strongly oxidized in the DOC, so that the temperature of the DOC rear exhaust temperature T5 rises to 600°C, achieving efficient regeneration of the DPF. Since the EHC heating function is turned on, the heating rate is increased, and the increase in fuel consumption caused by the heating in the low-temperature stage is reduced, thereby shortening the regeneration time. When the DOC front exhaust temperature T4 is greater than or equal to the set second temperature threshold (such as 350°C), the reheating mode is exited.

[0031] Light heating mode: When the power battery SOC is greater than or equal to the minimum threshold a1, and the DPF outlet temperature T6 is less than the set first temperature threshold (such as 220°C), the vehicle's 48V system enters the light heating mode. Specifically, the power battery provides electrical energy to the EHC of the post-processing system so that the DPF outlet temperature T6 is equal to or greater than the first temperature threshold, and the DPF outlet temperature T6 is maintained at the first temperature threshold.

[0032] The temperature T6 at the DPF outlet is above the first temperature threshold and belongs to the high-efficiency area of ​​SCR operation. The SCR conversion efficiency is very high and can convert most of the engine's NOx harmful gases to achieve ultra-low NOx emissions.

[0033] In addition, when the vehicle is operating in a cold environment or the vehicle speed and load are less than the set corresponding thresholds or the exhaust temperature is lower than the set exhaust temperature threshold, the light heating mode is triggered, which can quickly increase the SCR temperature to make the catalyst operate in the high-efficiency zone and maintain ultra-low NOx emissions.

[0034] When the temperature T6 at the DPF outlet is greater than or equal to a third temperature threshold (eg, 260° C.), the light heating mode is exited.

[0035] like Figure 2As shown, a low-emission and low-fuel-consumption National VII diesel engine control device includes an ECU, a 48V system 1 and a post-processing system 2. Among them, the 48V system 1 is connected to the power end of the diesel engine 3, and the post-processing system 2 is connected to the exhaust end of the diesel engine 3. The 48V system 1 includes a generator 11, a controller 12 and a power battery 13, and the post-processing system 2 includes EHC21, DOC22, DPF23 and SCR24; a first power supply line is provided between the generator 11 and the EHC21, and a second power supply line is provided between the power battery 13 and the EHC21. A linkage relay 14 is provided on the first power supply line and the second power supply line, and a DC-DC driver 15 is provided on the second power supply line. Among them, the linkage relay 14 is used to control the on-off of the two power supply lines, realize the switching of the power supply of the generator 11 and the power battery 13 to the EHC21 to ensure the support of the electric energy required by the EHC21 and ensure the normal operation of the EHC21. The DC-DC driver 15 is used to control the output power of the power battery 13 to the EHC 21, dynamically adjust the required heating power of the EHC 21, and ensure accurate control of the required temperature of each component of the post-processing system. In the actual working process of the EHC 21, its heating power is dynamically adjusted in order to meet the rapid increase in the temperature of the corresponding components in the post-processing system 2. Specifically, the required heating power of the EHC 21 is dynamically adjusted according to the current exhaust flow rate in the post-processing system 2 and the current exhaust temperature of the corresponding components.

[0036] According to the received engine control requirements, the ECU controls the generator 11, the power battery 13, the DC-DC driver 15 and the linkage relay 14 respectively through the above control method, thereby meeting the engine operation requirements and having the advantages of low fuel consumption, low emissions and high safety.

[0037] The above is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the structure of the present invention, which will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. A low-emission and low-fuel-consumption National VII diesel engine control method, characterized in that: The control method comprises: collecting the running state and the post-processing regeneration state of the vehicle, and determining the running mode of the 48V system of the vehicle according to the running state and the post-processing state; the running mode comprises: Charging mode: When the SOC of the power battery of the 48V system of the vehicle is less than the set minimum threshold a1, the 48V system of the vehicle enters the charging mode; Power-assist mode: When the vehicle is in an accelerating state and the power battery SOC is greater than or equal to a minimum threshold a1, the vehicle's 48V system enters the power-assist mode; Reheating mode: when it is detected that the vehicle is in DPF driving regeneration and the power battery SOC is greater than or equal to the minimum threshold a1, the vehicle's 48V system enters the reheating mode; Light heating mode: When the power battery SOC is greater than or equal to the minimum threshold a1, and the temperature T6 at the DPF outlet is less than the set first temperature threshold, the vehicle's 48V system enters the light heating mode.

2. A low-emission and low-fuel-consumption National VII diesel engine control method according to claim 1, characterized in that: The reheating mode is: the power battery provides electric energy to the EHC of the post-processing system, so that the EHC enters a set high-power state to quickly increase the DOC front exhaust temperature T4 to a set target temperature threshold.

3. A low-emission and low-fuel-consumption National VII diesel engine control method according to claim 2, characterized in that: During the reheating mode, if the power battery SOC is less than the minimum threshold a1, the 48V system is controlled to enter the charging mode, the power battery is stopped from outputting electrical energy, and the power battery is charged. At the same time, the EHC is powered by the generator of the 48V system to ensure that the EHC still operates in the set high power state.

4. A low-emission and low-fuel-consumption National VII diesel engine control method according to claim 2 or 3, characterized in that: When the DOC front exhaust temperature T4 is greater than or equal to a set second temperature threshold, the reheating mode is exited.

5. The low-emission and low-fuel-consumption National VII diesel engine control method according to claim 1 is characterized in that: The light heating mode is: the power battery provides electric energy to the EHC of the post-processing system, so that the temperature T6 at the DPF outlet is equal to or greater than the first temperature threshold, and the temperature T6 at the DPF outlet is maintained at a minimum at the first temperature threshold.

6. A low-emission and low-fuel-consumption National VII diesel engine control method according to claim 1, characterized in that: The light heating mode is triggered when the vehicle is running in a cold environment or the vehicle speed and load are both less than the set corresponding thresholds or the exhaust temperature is lower than the set exhaust temperature threshold.

7. A low-emission and low-fuel-consumption National VII diesel engine control method according to claim 1, 5 or 6, characterized in that: When the temperature T6 at the DPF outlet is greater than or equal to a third temperature threshold, the light heating mode is exited.

8. The low-emission and low-fuel-consumption National VII diesel engine control method according to claim 1 is characterized in that: The power-assisting mode is as follows: the power battery discharges the flywheel motor, and the flywheel motor assists the engine in doing work to increase power output, so that the vehicle speed is quickly increased to a target value.

9. A low-emission and low-fuel-consumption National VII diesel engine control device, characterized in that: It includes an ECU, a 48V system and a post-processing system; the 48V system includes a generator, a controller and a power battery, and the post-processing system includes an EHC, a DOC, a DPF and an SCR; a first power supply line is provided between the generator and the EHC, a second power supply line is provided between the power battery and the EHC, a linkage relay is provided on the first power supply line and the second power supply line, and a DC-DC driver is provided on the second power supply line; the ECU uses the control method described in any one of claims 1 to 8 to control the operation of the 48V system.

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