Engine exhaust temperature control device, method and system

Abstract

The invention provides an engine exhaust temperature control device, method and system, and the device comprises a cylinder which is provided with a cylinder air inlet and a cylinder air outlet; the first pipeline is provided with a first air inlet and a first exhaust port, and the first air inlet is communicated with the air cylinder air inlet; the first one-way valve is mounted on the first pipeline; the second pipeline is provided with a second air inlet and a second air outlet, the second air inlet is communicated with the first air outlet, and the second air outlet is communicated with the first air inlet; the control valve is mounted on the first exhaust port and the second air inlet; and the intercooler is provided with an intercooler air inlet and an intercooler air outlet, and the intercooler air outlet communicates with the second air outlet. The problems that the exhaust temperature adjusting means of the engine is single, and effective adjustment of the exhaust temperature of the engine within the full working condition range cannot be achieved are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of engines, in particular to an engine exhaust temperature control device, an engine exhaust temperature control method and an engine exhaust temperature control system. BACKGROUND

[0002] The exhaust temperature of an internal combustion engine varies greatly under different operating conditions. Under high load operating conditions, the engine exhaust temperature rises significantly, which can easily cause overheating failure of key components such as turbochargers and exhaust pipes, affecting the reliability and service life of the entire machine. Under low load operating conditions, the engine exhaust temperature is too low to ensure that the exhaust aftertreatment system is in the optimal operating temperature range, resulting in a decrease in catalytic conversion efficiency and an increase in pollutant emissions.

[0003] In the prior art, common exhaust temperature adjustment methods mainly rely on the exhaust gas recirculation (EGR) system or its bypass pipeline. However, such methods can only work under certain pressure conditions, for example, effective adjustment can only be achieved when the pre-turbine pressure is higher than the post-intercooler pressure. When the post-intercooler pressure is higher than the pre-turbine pressure, there is a lack of effective control means, and there is a significant adjustment blind area.

[0004] Therefore, the exhaust temperature adjustment means in the prior art is relatively single, and it is difficult to effectively control the exhaust temperature of the engine under full operating conditions, and it is difficult to simultaneously consider the high load reliability of the engine, the low load emission efficiency, and the nitrogen oxide emission control requirements under high speed operating conditions. SUMMARY

[0005] The main purpose of the present application is to provide an engine exhaust temperature control device, an engine exhaust temperature control method and an engine exhaust temperature control system to at least solve the problem that the exhaust temperature adjustment means in the prior art is single and cannot effectively adjust the exhaust temperature of the engine under full operating conditions.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present application, an engine exhaust temperature control device is provided, comprising: a cylinder having a cylinder intake port and a cylinder exhaust port; a first pipeline having a first intake port and a first exhaust port, the first intake port being in communication with the cylinder intake port; a first one-way valve installed on the first pipeline; a second pipeline having a second intake port and a second exhaust port, the second intake port being in communication with the first exhaust port, and the second exhaust port being in communication with the first intake port; a control valve installed on the first exhaust port and the second intake port; and an intercooler having an intercooler intake port and an intercooler exhaust port, the intercooler exhaust port being in communication with the second exhaust port.

[0007] Optionally, the second pipeline further comprises: a first branch having a first branch air inlet and a first branch air outlet, comprising an EGR cooler and a second one-way valve, the first branch air inlet being communicated with the EGR cooler air inlet through the control valve, the EGR cooler air outlet being communicated with the first air inlet through the second one-way valve; a second branch having a second branch air inlet and a second branch air outlet, the second branch air inlet being communicated with the EGR cooler air outlet through the control valve, the first branch air inlet and the second branch air inlet jointly constituting the second air inlet.

[0008] Optionally, the engine exhaust temperature control device further comprises: a turbocharger having a third air inlet and a third air outlet, the third air outlet being communicated with the intercooler air inlet.

[0009] According to another aspect of the present application, an engine exhaust temperature control method is provided, which is applied to any one of the engine exhaust temperature control devices, and comprises: obtaining an external characteristic curve and a universal characteristic curve of an engine; dividing the universal characteristic curve into a plurality of regions according to the external characteristic curve, the regions representing working conditions of the engine; determining a target region from the plurality of regions according to a current working condition of the engine; determining a control strategy of the engine exhaust temperature control device corresponding to the target region, the control strategy comprising controlling the first pipeline and the second pipeline to be on or off through the control valve to adjust the exhaust temperature of the engine.

[0010] Optionally, the plurality of regions comprise a first region, a second region and a third region, the first region being a region where the engine speed is less than a first preset speed and the engine load is greater than a first preset load, the second region being a region where the engine speed is greater than or equal to the first preset speed and the engine load is greater than the first preset load, the third region being a region where the engine load is less than or equal to the first preset load, and determining a target region from the plurality of regions according to a current working condition of the engine comprises: obtaining the engine speed and the engine load; in the case where the engine speed is less than the first preset speed and the engine load is greater than the first preset load, determining the first region as the target region; in the case where the engine speed is greater than or equal to the first preset speed and the engine load is greater than the first preset load, determining the second region as the target region; in the case where the engine load is less than or equal to the first preset load, determining the third region as the target region.

[0011] Optionally, the engine exhaust temperature control device comprises a turbocharger, and after determining that the first region is the target region, the method further comprises: controlling the intake amount of the turbocharger to be raised to a preset intake amount.

[0012] Optionally, determining the control strategy of the engine exhaust temperature control device corresponding to the target region comprises: determining the control strategy of the engine exhaust temperature control device corresponding to the target region according to a preset mapping relationship table of the target region and the control strategy, wherein the target region and the control strategy are in one-to-one correspondence.

[0013] Optionally, the engine exhaust temperature control device comprises a first branch and a second branch, and after determining the control strategy of the engine exhaust temperature control device corresponding to the target region according to the preset mapping relationship table of the target region and the control strategy, the method further comprises: in the case that the target region is a first region, controlling the control valve to open the first pipe and close the first branch and the second branch; in the case that the target region is a second region, controlling the control valve to open the first branch and close the first pipe and the second branch; and in the case that the target region is a third region, controlling the control valve to open the second branch and close the first pipe and the first branch.

[0014] Optionally, the engine exhaust temperature control device comprises a first branch and a second branch, and after determining the control strategy of the engine exhaust temperature control device corresponding to the target region, the method further comprises: in the case that the exhaust temperature of the engine is greater than a preset temperature and has been greater than the preset temperature for a preset time length, and the engine speed is less than a first preset speed, controlling the control valve to open the first pipe and close the first branch and the second branch; in the case that the exhaust temperature of the engine is greater than the preset temperature and has been greater than the preset temperature for the preset time length, and the engine speed is greater than or equal to the first preset speed, controlling the control valve to open the first branch and close the first pipe and the second branch; and in the case that the exhaust temperature of the engine is less than or equal to the preset temperature and has been less than or equal to the preset temperature for the preset time length, controlling the control valve to open the second branch and close the first pipe and the first branch.

[0015] According to still another aspect of the present application, there is provided an engine exhaust temperature control system, comprising: any one of the engine exhaust temperature control devices; and an electronic control unit in communication with the engine exhaust temperature control device, configured to execute any one of the engine exhaust temperature control methods.

[0016] The technical scheme of the application is applied, the first pipeline is arranged, so that the air after intercooling can directly enter the cylinder air inlet under the action of the control valve, and the one-way flow of the gas is ensured through the first one-way valve, so that the air intake can be effectively increased and the exhaust temperature can be reduced at low speed and high load of the engine; the second pipeline is communicated with the cylinder exhaust port and the first exhaust port through the control valve, so that part of the exhaust gas can selectively enter the cylinder air inlet under different working conditions, the exhaust gas recirculation function is realized, the combustion temperature can be reduced at high speed and high load of the engine, the nitrogen oxide emission is reduced, and the exhaust temperature is increased through the exhaust gas bypass at low load, so that the exhaust aftertreatment system is ensured to be in the high-efficiency conversion interval. The intercooler is communicated with the second exhaust port, so that the gas entering the cylinder is effectively cooled when needed. The device can flexibly switch different airflow paths according to the actual working condition of the engine, avoid the control blind area caused by the single EGR path in the prior art, realize the effective control of the exhaust temperature of the engine in the full working condition range of low speed, high speed and low load, and solve the problem that the engine exhaust temperature adjusting means is single and the exhaust temperature of the engine cannot be effectively adjusted in the full working condition range. BRIEF DESCRIPTION OF DRAWINGS

[0017] The drawings accompanying the specification of the present application form a part thereof, serve to provide further understanding of the present application, and together with the description of the present application, serve to explain the present application. In the drawings:

[0018] Figure 1 An engine exhaust temperature control device provided according to an embodiment of the present application is shown in a diagram;

[0019] Figure 2 Another engine exhaust temperature control device provided according to an embodiment of the present application is shown in a diagram;

[0020] Figure 3 A flowchart of an engine exhaust temperature control method provided according to an embodiment of the present application is shown in a diagram;

[0021] Figure 4 A flowchart of determining a target region from multiple regions according to the current working condition of an engine provided according to an embodiment of the present application is shown in a diagram;

[0022] Figure 5 A flowchart of another engine exhaust temperature control method provided according to an embodiment of the present application is shown in a diagram;

[0023] Figure 6 A region division diagram of an engine universal curve provided according to an embodiment of the present application is shown in a diagram.

[0024] Among the above drawings, the following reference signs are included:

[0025] 100, cylinder; 200, first pipeline; 300, first one-way valve; 400, second pipeline; 410, first branch; 411, EGR cooler; 412, second one-way valve; 420, second branch; 500, control valve; 600, intercooler. DETAILED DESCRIPTION

[0026] It should be noted that the embodiments and features in the present application can be combined with each other without conflict. The technical solutions in the embodiments of the present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0027] In order for those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0028] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above-described accompanying drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0029] As introduced in the background, the existing engine exhaust temperature regulation means is single, and cannot realize effective regulation of the exhaust temperature of the engine in the whole working condition range. To solve the above technical problems, the embodiments of the present application provide an engine exhaust temperature control device, an engine exhaust temperature control method and an engine exhaust temperature control system.

[0030] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings.

[0031] Figure 1 is a diagram of an engine exhaust temperature control device according to the embodiments of the present application. As shown in Figure 1 the device includes:

[0032] a cylinder 100 having a cylinder intake port and a cylinder exhaust port;

[0033] Specifically, it can be a single cylinder, or a collection of multiple cylinders, such as a four-cylinder, six-cylinder or multi-cylinder engine.

[0034] The first pipeline 200 has a first intake port and a first exhaust port, and the first intake port is in communication with the cylinder 100 intake port.

[0035] Specifically, in the case of multiple cylinders, the intake port of each cylinder is connected to the first pipeline through a common intake manifold.

[0036] The first one-way valve 300 is installed on the first pipeline 200.

[0037] Specifically, the first one-way valve can be arranged at one end close to the cylinder intake port, or can be arranged at the middle section or other positions of the first pipeline according to the pipeline arrangement, to realize the one-way conduction function.

[0038] The second pipeline 400 has a second intake port and a second exhaust port, the second intake port is in communication with the first exhaust port, and the second exhaust port is in communication with the first intake port.

[0039] The control valve 500 is installed on the first exhaust port and the second intake port.

[0040] Specifically, the second pipeline can re-introduce part of the gas flow from the first pipeline to the cylinder intake side, or re-distribute part of the exhaust gas to the intake end, according to the opening or closing state of the control valve, so as to realize the regulation of the engine exhaust temperature.

[0041] The intercooler 600 has an intercooler intake port and an intercooler exhaust port, and the intercooler exhaust port is in communication with the second exhaust port.

[0042] Through the above embodiments, by setting up a first pipeline, the intercooled air can directly enter the cylinder intake port under the action of a control valve, and the first one-way valve ensures unidirectional gas flow, thereby effectively increasing the intake volume and reducing the exhaust temperature when the engine is at low speed and high load. The second pipeline is connected to the cylinder exhaust port and the first exhaust port through control valves, allowing some exhaust gas to selectively enter the cylinder intake port under different operating conditions, realizing the exhaust gas recirculation function. At high engine speed and high load, it can reduce the combustion temperature and reduce nitrogen oxide emissions, while at low load, it can increase the exhaust temperature through exhaust gas bypass, ensuring that the exhaust gas after-treatment system is in the high-efficiency conversion range. The intercooler is connected to the second exhaust port, ensuring that the gas entering the cylinder is effectively cooled when needed. This device can flexibly switch different airflow paths according to the actual engine operating conditions, avoiding the control blind spots caused by relying on a single EGR path in the prior art. It can effectively control the exhaust temperature of the engine across the entire operating range, including low speed, high speed, and low load, solving the problem of the single exhaust temperature adjustment method that cannot effectively adjust the exhaust temperature of the engine across the entire operating range.

[0043] In one alternative, such as Figure 2 As shown, the second pipeline further includes: a first branch 410, having a first branch inlet and a first branch outlet, including an EGR cooler 411 and a second check valve 412, wherein the first branch inlet is connected to the EGR cooler inlet through the control valve 500, and the EGR cooler outlet is connected to the first inlet through the second check valve 412; and a second branch 420, having a second branch inlet and a second branch outlet, wherein the second branch inlet is connected to the EGR cooler outlet through the control valve 500, and the first branch inlet and the second branch inlet together constitute the second inlet.

[0044] In the above embodiment, the first branch is provided with an EGR cooler and a second one-way valve. When the control valve controls the first branch to be conductive, part of the high-temperature exhaust gas is cooled by the EGR cooler and then enters the intake end of the first branch through the second one-way valve, so as to reduce the cylinder combustion temperature in the high-speed high-load and emission control area, reduce the NOx (nitrogen oxide) emission, and at the same time avoid the adverse effects of high exhaust gas temperature on the reliability of the engine. The setting of the second one-way valve can prevent the backflow of the gas in the intake end, and improve the stability and safety of the gas delivery. When the control valve controls the second branch to be conductive, part of the high-temperature exhaust gas which has not been cooled directly enters the intake end from the exhaust port of the EGR cooler, so as to quickly increase the exhaust gas temperature after the cylinder combustion. It is especially suitable for the low-load area, so as to increase the exhaust gas temperature in a short time, which is helpful for the exhaust aftertreatment system to quickly enter the high-efficiency working interval, so as to improve the conversion efficiency of pollutants. By setting the first branch and the second branch, the exhaust gas temperature can be flexibly switched between reducing the exhaust gas temperature in the high-load area and increasing the exhaust gas temperature in the low-load area according to the needs of different engine operating areas, so as to adjust the exhaust gas temperature according to the engine working condition.

[0045] In another alternative, the engine exhaust temperature control device further comprises a turbocharger having a third intake port and a third exhaust port, and the third exhaust port is in communication with the intercooler intake port.

[0046] In the above embodiment, the turbocharger drives the compressor to rotate by using the energy of the high-temperature exhaust gas discharged from the engine, so as to increase the pressure and flow of the intake air. The compressed air is cooled by the intercooler before entering the cylinder, which can increase the air density and improve the combustion efficiency and engine output power. On this basis, in combination with the adjusting effect of the first pipeline, the second pipeline and the control valve, the exhaust gas temperature can be accurately controlled under different working conditions. The turbocharger and the intercooler improve the power output of the engine, and at the same time provide more stable gas source conditions for subsequent multi-path exhaust gas temperature adjustment. In combination with the pipeline switching control under different working conditions, the exhaust aftertreatment efficiency of the engine can be further improved.

[0047] The embodiment also provides an engine exhaust temperature control method applied to the engine exhaust temperature control device, as shown in Figure 3 , comprising:

[0048] In step S101, the external characteristic curve and the universal characteristic curve of the engine are obtained;

[0049] In step S102, the universal characteristic curve is divided into a plurality of regions according to the external characteristic curve, and the regions represent the working conditions of the engine;

[0050] Specifically, the external characteristic curve can reflect the typical performance of the engine under full load conditions with the change of the rotating speed, and the universal characteristic curve can reflect the overall operating state of the engine under different loads and different fuel injection amounts. By combining the external characteristic curve and the universal characteristic curve for analysis, the operating range of the engine can be divided in a targeted manner.

[0051] In step S103, a target region is determined from the plurality of regions according to the current operating condition of the engine.

[0052] In step S104, a control strategy of the engine exhaust temperature control device corresponding to the target region is determined, and the control strategy includes controlling the first pipeline and the second pipeline to be turned on or turned off by the control valve to adjust the exhaust temperature of the engine.

[0053] In the above embodiment, first, by obtaining the external characteristic curve and the universal characteristic curve of the engine, the operating characteristics of the engine under different rotating speeds and different loads can be comprehensively reflected, including parameters such as power, torque, fuel consumption rate, and exhaust temperature. Then, the universal characteristic curve is divided into a plurality of regions according to the external characteristic curve, so that different operating condition characteristics can be clearly distinguished in the full operating range of the engine. For example, the medium-low rotating speed and medium-high load region is prone to the risk of excessively high exhaust temperature, the high-speed and high-load region needs to balance the power and emission control, and the low-load region has the problem of insufficient exhaust temperature and difficulty in efficient operation of the aftertreatment system. By dividing into a plurality of regions, different control means can be taken in different regions in a targeted manner. By flexibly adjusting the turning on or turning off of the first pipeline and the second pipeline by the control valve, precise control of the exhaust temperature of the engine in the full operating range is achieved. Not only the power of the engine under high load conditions is improved, but also the emission performance under low load conditions is improved, so that the engine can balance the power, economy, and environmental protection.

[0054] For example, with reference to the external characteristic curve, the maximum load boundary that the engine can reach under different rotating speeds is determined; within the boundary, regions are set according to the rotating speed and the load threshold, for example: when the rotating speed is less than a first preset rotating speed and the load is higher than a first preset load, it is defined as a medium-low rotating speed and medium-high load region; when the rotating speed is greater than or equal to the first preset rotating speed and the load is higher than the first preset load, it is defined as a high-speed and high-load region; when the load is less than or equal to the first preset load, it is defined as a low-load region. Using the universal characteristic curve after region division, the operating condition attribution of the engine at different operating points can be directly marked, thereby providing a basis for the subsequent exhaust temperature adjustment strategy.

[0055] In an alternative, the plurality of regions includes a first region, a second region, and a third region, the first region is a region where the engine speed is less than a first preset speed and the engine load is greater than a first preset load, the second region is a region where the engine speed is greater than or equal to the first preset speed and the engine load is greater than the first preset load, and the third region is a region where the engine load is less than or equal to the first preset load, and a target region is determined from the plurality of regions according to a current operating condition of the engine, such as Figure 4 as shown, comprising:

[0056] In step S201, the engine speed and the engine load are obtained.

[0057] In step S202, in a case where the engine speed is less than the first preset speed and the engine load is greater than the first preset load, the first region is determined as the target region.

[0058] In step S203, in a case where the engine speed is greater than or equal to the first preset speed and the engine load is greater than the first preset load, the second region is determined as the target region.

[0059] In step S204, in a case where the engine load is less than or equal to the first preset load, the third region is determined as the target region.

[0060] In the above embodiments, first, by dividing the operating range of the engine into a first region, a second region and a third region, different operating conditions can be clearly distinguished, avoiding the problem of insufficient control accuracy caused by using a unified control strategy for all operating conditions in traditional methods, so that exhaust temperature regulation can be more targeted and accurate. In the first region, i.e. the low-medium speed high load condition where the engine speed is lower than the first preset speed and the load is higher than the first preset load, the problem of excessively high exhaust temperature is prone to occur. By identifying this region, measures can be taken to reduce the exhaust temperature in time, avoiding the decline in engine part reliability caused by high temperature. In the second region, i.e. the high speed high load condition where the engine speed is greater than or equal to the first preset speed and the load is higher than the first preset load, the combustion temperature is relatively high and the NOx emission pressure is relatively large. By identifying this region, the EGR cooling circuit can be switched to in time to introduce cooled exhaust gas to reduce the combustion temperature, thereby effectively reducing NOx emissions while taking into account fuel economy. In the third region, i.e. the low load condition where the engine load is lower than or equal to the first preset load, the combustion temperature is insufficient and the exhaust temperature is too low, which can easily lead to the aftertreatment system failing to maintain in the high-efficiency working interval. By identifying this region, the second branch, i.e. the EGR bypass pipeline, can be switched to in time to introduce high-temperature exhaust gas without cooling to increase the exhaust temperature and promote the exhaust aftertreatment system to quickly enter and maintain a high-efficiency conversion state, thereby reducing the emission of pollutants such as HC and CO. By obtaining the engine speed and load in real time and comparing them with the preset threshold, the target region can be determined dynamically, which can ensure that the exhaust temperature control strategy matched with different operating conditions of the engine is always selected, further solving the problem in the prior art that the engine exhaust temperature regulation means is single and cannot effectively regulate the exhaust temperature of the engine in the full operating range.

[0061] Exemplarily, the first region is a working condition where the engine speed is less than a first preset speed and the engine load is greater than a first preset load, at this time, it belongs to a medium-low speed and high load region, the engine output torque is relatively large, and the exhaust temperature is prone to be high, so measures need to be taken to reduce the exhaust temperature to ensure reliability. The second region is a working condition where the engine speed is greater than or equal to the first preset speed and the engine load is greater than the first preset load, at this time, it belongs to a high speed and high load region, the engine combustion temperature is high, the exhaust temperature is also high, and the nitrogen oxide emission pressure is large, so the EGR cooling method needs to be taken to balance the power and emission control. The third region is a working condition where the engine load is less than or equal to the first preset load, at this time, it belongs to a low load region, the combustion temperature is low, which leads to insufficient exhaust temperature, and it is difficult to maintain the exhaust aftertreatment system to operate in the high-efficiency working interval, so the high-temperature exhaust gas without cooling needs to be introduced to increase the exhaust temperature, thereby improving the aftertreatment efficiency. The control unit obtains the current speed and load of the engine, and compares them with the preset speed threshold and load threshold. If the speed is less than the first preset speed and the load is greater than the first preset load, it is determined that the engine is currently in the first region; if the speed is greater than or equal to the first preset speed and the load is greater than the first preset load, it is determined that the engine is currently in the second region; if the load is less than or equal to the first preset load, it is determined that the engine is currently in the third region. In this way, the target region of the engine can be determined, which provides a basis for subsequent selection of the corresponding exhaust temperature control strategy.

[0062] In another optional solution, the engine exhaust temperature control device includes a turbocharger, and after it is determined that the first region is the target region, the method further includes: controlling the intake amount of the turbocharger to increase to a preset intake amount.

[0063] In the above embodiment, the first region corresponds to a working condition where the engine is in a medium-low speed and high load state, at this time, the engine needs a large amount of air for combustion, but if the intake amount is insufficient, it is easy to cause the combustion process to be too intense, the exhaust temperature to rise rapidly, and thus the heat load on engine parts such as exhaust valves and turbine blades to be too high. By increasing the intake amount of the turbocharger, the amount of air in the cylinder can be effectively increased, the mixing of fuel and air can be more diluted, the combustion temperature can be reduced, and the problem of excessively high exhaust temperature can be avoided from the source. By increasing the intake amount, the charging efficiency in the cylinder can be enhanced, the combustion can be more complete, the combustion stability and fuel utilization rate can be improved, which is helpful to improve the power of the engine in the medium-low speed working condition, and also can reduce fuel consumption and improve the economy of the whole machine. In the case of increasing the intake amount, the compressor operating point will move to the high-efficiency region, which is helpful to improve the efficiency of the compressor and improve the transient response capability of the engine in the low speed working condition, so that the acceleration performance of the whole machine is better.

[0064] In some example embodiments of the present application, determining the control strategy of the engine exhaust temperature control device corresponding to the target region comprises: determining the control strategy of the engine exhaust temperature control device corresponding to the target region according to a preset mapping relationship table of the target region and the control strategy, and the target region and the control strategy are one-to-one corresponding.

[0065] In the above embodiments, the target region corresponding to the current operating condition of the engine is determined through the mapping relationship table, without the need for complex real-time calculation or manual judgment, so that the corresponding control strategy can be directly called, the control response time is shortened, the real-time performance and stability of the control system are improved, and the definiteness and pertinence of the control logic are also ensured. In addition, in actual application, the region boundaries and corresponding strategies in the mapping relationship table can be flexibly adjusted according to the performance characteristics of the engine or the emission regulation requirements, so as to adapt to the needs of different engine models or different application scenarios, without the need for substantial modification of the overall control logic, thereby improving the real-time performance, reliability and adaptability of the control.

[0066] In some example embodiments of the present application, the engine exhaust temperature control device comprises a first branch and a second branch, and after determining the control strategy of the engine exhaust temperature control device corresponding to the target region according to the preset mapping relationship table of the target region and the control strategy, the method further comprises: in the case that the target region is a first region, controlling the control valve to open the first pipeline and close the first branch and the second branch; in the case that the target region is a second region, controlling the control valve to open the first branch and close the first pipeline and the second branch; and in the case that the target region is a third region, controlling the control valve to open the second branch and close the first pipeline and the first branch.

[0067] In the above embodiment, when the target region is the first region, i.e., the engine is in the working condition of medium-low speed and high load, the engine is prone to have the problem of excessively high exhaust temperature. At this time, the control valve opens the first pipeline, i.e., the intake bypass pipeline, so that the air after intercooling bypasses the compressor and directly enters the pre-turbine to dilute the combustion temperature, thereby effectively reducing the exhaust temperature; at the same time, the first branch, i.e., the EGR cooling pipeline, and the second branch, i.e., the EGR bypass pipeline, are closed to avoid the instability of the control effect caused by the additional exhaust gas. When the target region is the second region, i.e., the engine is in the working condition of high speed and high load, both the combustion temperature and the NOx emission pressure are large. At this time, the control valve opens the first branch, so that part of the high-temperature exhaust gas is cooled by the EGR cooler and then introduced into the cylinder again, thereby reducing the combustion temperature and reducing the generation of NOx; at the same time, the first pipeline and the second branch are closed to ensure the stability of the EGR cooling effect. When the target region is the third region, i.e., the engine is in the working condition of low load, the combustion temperature is insufficient and the exhaust temperature is low, which is not conducive to the efficient work of the exhaust aftertreatment system. At this time, the control valve opens the second branch, so that the high-temperature exhaust gas without cooling directly enters the cylinder, thereby increasing the temperature of the exhaust gas after combustion and accelerating the exhaust aftertreatment device to enter the high-efficiency conversion interval; at the same time, the first pipeline and the first branch are closed to avoid the influence of intake dilution or EGR cooling on the warming-up effect. Through the above pipeline switching mode corresponding to different regions, the exhaust temperature of the engine can be accurately adjusted in the whole working condition range, the temperature is reduced for protection in the high-load working condition, the NOx emission is reduced in the high-speed working condition, and the aftertreatment efficiency is improved in the low-load working condition, so as to balance the power, economy and environmental protection of the engine.

[0068] In an optional solution, the engine exhaust temperature control device includes a first branch and a second branch. After determining the control strategy of the engine exhaust temperature control device corresponding to the target region, the method further includes: in the case that the exhaust temperature of the engine is greater than a preset temperature and has been greater than the preset temperature for a preset time period, and the engine speed is less than a first preset speed, controlling the control valve to open the first pipeline and close the first branch and the second branch; in the case that the exhaust temperature of the engine is greater than the preset temperature and has been greater than the preset temperature for the preset time period, and the engine speed is greater than or equal to the first preset speed, controlling the control valve to open the first branch and close the first pipeline and the second branch; and in the case that the exhaust temperature of the engine is less than or equal to the preset temperature and has been less than or equal to the preset temperature for the preset time period, controlling the control valve to open the second branch and close the first pipeline and the first branch.

[0069] In the above embodiments, the exhaust temperature of the engine may fluctuate for a short time when the engine is accelerating, decelerating, or the load is rapidly changing. If only the instantaneous temperature is used as the basis for judgment, it is easy to cause the control valve to open and close frequently, causing the control strategy to jitter. By introducing the preset time condition, the pipeline switching is triggered only when the exhaust temperature continuously exceeds or is lower than the threshold value for a period of time, effectively avoiding the misoperation caused by transient fluctuations, ensuring that the control strategy can operate stably after switching, and will not be repeatedly switched due to short-term working condition fluctuations, improving the reliability and predictability of the control. The exhaust aftertreatment system needs to work in a relatively stable temperature environment to maintain high efficiency. By increasing the preset time constraint, the exhaust temperature can be prevented from fluctuating greatly due to frequent switching, thereby providing a more stable working temperature environment for the aftertreatment system and improving its conversion efficiency and service life.

[0070] Specifically, the preset temperature for determining whether the engine exhaust temperature needs to be adjusted is obtained through engine bench tests, combined with the exhaust temperature distribution of the engine under different loads and speeds, and a temperature threshold value that can balance the engine reliability and exhaust aftertreatment efficiency is selected. For example, when the exhaust temperature exceeds a certain set value that may cause the turbocharger or exhaust valve to overheat, the set value can be used as the above-mentioned preset temperature; the first preset speed is used to divide the boundary between low-speed and high-speed working conditions, and is determined based on the engine external characteristic curve, i.e., at the speed point where the engine torque curve decreases significantly or the supercharging system efficiency changes. For example, for a heavy-duty diesel engine, the speed value is usually in the range of 50% to 70% of the rated speed; the preset time is used to avoid the control valve opening and closing frequently due to the transient working condition fluctuations of the engine. The time can be determined according to the dynamic response characteristics of the engine and the temperature adaptation requirements of the aftertreatment system. Through test calibration, the control valve is only switched when the exhaust temperature continuously exceeds or is lower than the threshold value for a period of time, thereby ensuring the stability of the control strategy.

[0071] The embodiments of the present application also provide an engine exhaust temperature control system, comprising: the above-mentioned engine exhaust temperature control device; an electronic control unit in communication with the above-mentioned engine exhaust temperature control device, for executing the above-mentioned engine exhaust temperature control method.

[0072] In the above embodiments, by combining the engine exhaust temperature control device with the electronic control unit to form a complete system, the exhaust temperature signal, the speed signal and the load signal of the engine under different working conditions can be transmitted to the electronic control unit in real time, and the corresponding control method is automatically executed by the electronic control unit, so as to realize the control of the exhaust temperature. The electronic control unit can determine the operating condition according to the engine external characteristic curve and the universal characteristic curve, and call the target region and control strategy mapping relationship table to quickly determine the current optimal pipeline switching mode. Compared with the mode of simply relying on mechanical valve control, higher precision control can be realized, and the problem of unstable control caused by artificial lag or valve misoperation can be avoided. Through real-time calculation and signal processing of the electronic control unit, the opening and closing state of the control valve can be quickly adjusted when the engine operating state changes, ensuring the timeliness of the exhaust temperature regulation, not only improving the power and economy of the engine, but also improving the emission performance.

[0073] In order to enable those skilled in the art to more clearly understand the technical solutions of the present application, the following will be described in detail in combination with specific embodiments.

[0074] The present embodiment relates to an engine exhaust temperature control method specifically applied to the above-mentioned engine exhaust temperature control device, as shown in Figure 5 The method comprises the following steps:

[0075] Step S1: obtaining the engine design external characteristic and universal characteristic curve;

[0076] Step S2: based on the engine speed and load, dividing the engine universal curve into three regions;

[0077] Specifically, as shown in Figure 6 Region ① is a medium-low speed and medium-high load region, region ② is a high-speed and high-load and emission control region, and region ③ is a low-load region.

[0078] Step S3: according to the three regions, different control modes are adopted respectively.

[0079] Specifically, in region ①, the pressure after intercooling is higher than the pressure before the turbine, the intake bypass pipeline, i.e. the first pipeline, is opened, and fresh air directly enters the pipeline before the turbine after intercooling, which can effectively reduce the exhaust temperature. Considering that the pressure before the turbine changes greatly with the crank angle, a one-way valve needs to be added to the intake bypass pipeline to expand the range of the use of the intake bypass. In the low-speed high-load region, due to the energy increase before the turbine, the intake amount increases, the risk of surging decreases, the combined operation line moves to the high-efficiency region of the compressor, and it is beneficial to improve the low-speed power. In region ②, the pressure before the turbine is higher than the pressure after intercooling, the EGR pipeline, i.e. the first branch, is opened, and the EGR exhaust gas enters the cylinder through the EGR cooler and the one-way valve. The EGR exhaust gas can effectively reduce the in-cylinder combustion temperature, reduce the NOx emission in the emission control region, and reduce the exhaust temperature at high speed and high load. In region ③, the load is low, the pressure before the turbine is higher than the pressure after intercooling, the EGR bypass pipeline, i.e. the second branch, is opened, and the hot EGR exhaust gas directly enters the cylinder through the one-way valve, which can quickly and effectively increase the exhaust temperature and reduce the emission of pollutants.

[0080] The embodiments of the present application also provide a specific application scenario of engine exhaust temperature control, which is applied to the operation control of a heavy-duty diesel engine under complex road conditions. When the vehicle is transporting in a mountainous area, the engine often experiences long-time high-load operation, and then enters a steep downhill working condition. At this time, the exhaust temperature will fluctuate greatly. By setting a preset temperature and a preset time, combined with the speed information of the engine, the electronic control unit can switch to the first pipeline or the first branch only after the exhaust temperature exceeds the threshold value for a certain time, thereby avoiding the frequent opening and closing of the control valve due to short-time fluctuations. In the low-load long-downhill working condition, when it is detected that the exhaust temperature is continuously lower than the threshold value and reaches the preset time, the system automatically switches to the second branch, so that the uncooled high-temperature exhaust gas enters the cylinder, increases the exhaust temperature, and ensures that the exhaust aftertreatment device remains in the high-efficiency working interval. In this way, the engine can not only avoid the problem of excessive heat load of parts under long-time complex working conditions, but also ensure the exhaust purification efficiency under low-temperature working conditions, thereby improving the overall reliability, emission performance and adaptability of the engine.

[0081] The embodiment of the present application also provides a specific implementation scene of determining a control strategy according to a mapping relationship table, which is applied to long-time standby and high-frequency loading and unloading operations of a port container truck. The vehicle operation characteristics are as follows: long-time low-speed idling or slow running, that is, in a low-load region, and short-time high-speed running when entering and leaving a port road, that is, in a high-speed high-load region, and frequent switching of working conditions. Through the preset mapping relationship table of the target region and the control strategy, the engine region can be quickly identified, and the corresponding control strategy can be immediately called: in the low-load idling working condition, the system is automatically switched to the EGR bypass passage, the exhaust temperature is increased, and the aftertreatment system is kept in an activated state; in the high-speed high-load working condition, the system is automatically switched to the EGR cooling passage, the combustion temperature and the NOx emission are effectively reduced; and in the medium-low speed high-load short-distance transportation, the intake bypass passage is preferentially opened to reduce the exhaust temperature under high load and improve the efficiency of the compressor. Through the quick calling of the mapping relationship table, the dynamic switching of the control strategy can be completed without complex calculation, so that the stable regulation of the engine exhaust temperature is realized in the frequent variable working condition scene, and the power performance, the emission performance and the efficiency of the aftertreatment system are considered.

[0082] It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0083] Obviously, those skilled in the art should understand that the above-mentioned modules or steps of the present application can be realized by a general computing device, which can be concentrated on a single computing device or distributed on a network composed of multiple computing devices, which can be realized by program codes executable by a computing device, so that they can be stored in a storage device and executed by a computing device, and in some cases, the steps shown or described can be executed in an order different from that shown here, or they can be manufactured into individual integrated circuit modules, or multiple modules or steps among them can be manufactured into a single integrated circuit module to realize. Therefore, the present application is not limited to any specific combination of hardware and software.

[0084] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can adopt a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer usable storage media containing computer usable program codes (including but not limited to disk storage, CD-ROM, optical storage, etc.).

[0085] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 means for functionally implementing the steps in the flowchart block or blocks

[0086] These computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 means for functionally implementing the steps in the flowchart block or blocks

[0087] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 means for functionally implementing the steps in the flowchart block or blocks

[0088] In one typical configuration, the computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0089] The memory can include non-persistent memory and / or volatile memory, such as a random access memory (RAM) including a cache area for the temporary storage of data. The memory can also include non-volatile memory, such as read only memory (ROM), electrically programmable read only memory (EPROM), or electrically erasable programmable read only memory (EEPROM), for the storage of software that is read during runtime. The memory is an example of computer readable media.

[0090] Computer-readable media includes permanent and non-permanent, movable and non-movable media that can be implemented by any method or technology to store information. The information can be computer-readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassette, magnetic tape disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information accessible by a computing device. According to the definition herein, computer-readable media does not include transitory media such as modulated data signals and carriers.

[0091] The technical features of the above-described embodiments can be combined in any manner. In order to make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, but as long as the combinations of the technical features do not exist contradictions, it should be considered as the scope of the present disclosure.

[0092] It should also be noted that the terms "comprising", "including", or any other variant thereof are intended to cover non-exclusive inclusion, so that processes, methods, articles or devices including a series of elements not only include those elements, but also include other elements not explicitly listed, or inherent to such processes, methods, articles or devices. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0093] From the above description, it can be seen that the above-described embodiments of the present application achieve the following technical effects:

[0094] 1) The engine exhaust temperature control device of the present application, by setting the first pipeline, so that the air after intercooling can be directly into the cylinder air inlet under the action of the control valve, and through the first check valve to ensure one-way flow of gas, so as to effectively increase the intake air, reduce the exhaust temperature at low speed and high load of engine; The second pipeline is communicated with the cylinder exhaust port and the first exhaust port through the control valve, so that part of the exhaust gas can selectively enter the cylinder air inlet under different working conditions, realizing the function of exhaust gas recirculation, which can reduce the combustion temperature and reduce the emission of nitrogen oxides at high speed and high load of engine, while increasing the exhaust temperature by exhaust gas bypass at low load to ensure that the exhaust aftertreatment system is in the high conversion interval. The intercooler is communicated with the second exhaust port, which ensures that the gas entering the cylinder is effectively cooled when needed. The device can flexibly switch different airflow paths according to the actual working condition of the engine, avoid the control blind area caused by relying on a single EGR path in the prior art, realize effective control of the exhaust temperature of the engine in the whole working condition range of low speed, high speed and low load, and solve the problem that the engine exhaust temperature adjustment method is single and cannot realize effective adjustment of the exhaust temperature of the engine in the whole working condition range.

[0095] 2) The engine exhaust temperature control method of the present application, first, by obtaining the external characteristic curve and the universal characteristic curve of the engine, the running characteristics of the engine under different speeds and different loads can be comprehensively reflected, including power, torque, fuel consumption rate and exhaust temperature and other parameters. Next, the universal characteristic curve is divided into multiple regions according to the external characteristic curve, which can clearly distinguish different working condition characteristics in the whole operating range of the engine. For example, the medium and low speed and high load region is prone to risk of excessive exhaust temperature, the high speed and high load region needs to consider power and emission control, and the low load region has insufficient exhaust temperature and the aftertreatment system is difficult to work efficiently. By dividing into multiple regions, different control methods can be taken in different regions. The control valve flexibly adjusts the conduction or closing of the first pipeline and the second pipeline, realizing precise control of the exhaust temperature of the engine in the whole working condition range. Not only improves the power of the engine under high load working condition, but also improves the emission performance under low load working condition, so that the engine can consider power, economy and environmental protection.

[0096] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An engine exhaust temperature control device, characterized in that, include: Cylinder (100) has a cylinder inlet and a cylinder exhaust port; The first pipeline (200) has a first air inlet and a first exhaust port, wherein the first air inlet is connected to the air inlet of the cylinder (100); The first check valve is installed on the first pipeline (200); The second pipeline (400) has a second air inlet and a second exhaust outlet, the second air inlet being connected to the first exhaust outlet and the second exhaust outlet being connected to the first air inlet; A control valve (500) is installed on the first exhaust port and the second intake port; An intercooler (600) has an intercooler inlet and an intercooler outlet, wherein the intercooler outlet is connected to the second outlet.

2. The engine exhaust temperature control device according to claim 1, characterized in that, The second conduit (400) also includes: The first branch (410) has a first branch air inlet and a first branch exhaust port, including an EGR cooler (411) and a second one-way valve (412). The first branch air inlet is connected to the EGR cooler air inlet through the control valve (500), and the EGR cooler exhaust port is connected to the first air inlet through the second one-way valve (412). The second branch (420) has a second branch air inlet and a second branch exhaust port. The second branch air inlet is connected to the EGR cooler exhaust port through the control valve (500). The first branch air inlet and the second branch air inlet together constitute the second air inlet.

3. The engine exhaust temperature control device according to claim 1, characterized in that, The engine exhaust temperature control device also includes: The turbocharger has a third air intake and a third exhaust port, the third exhaust port being connected to the intercooler intake port.

4. A method for controlling engine exhaust temperature, characterized in that, The engine exhaust temperature control device applied to any one of claims 1 to 3, wherein the engine exhaust temperature control method comprises: Obtain the engine's external characteristic curves and universal characteristic curves; The universal characteristic curve is divided into multiple regions based on the external characteristic curve, and the regions characterize the operating conditions of the engine. The target area is determined from the multiple regions based on the current operating condition of the engine; A control strategy for the engine exhaust temperature control device corresponding to the target area is determined. The control strategy includes controlling the opening or closing of the first and second pipelines through control valves to adjust the exhaust temperature of the engine.

5. The method according to claim 4, characterized in that, The plurality of regions includes a first region, a second region, and a third region. The first region is the region where the engine speed is less than a first preset speed and the engine load is greater than a first preset load. The second region is the region where the engine speed is greater than or equal to the first preset speed and the engine load is greater than the first preset load. The third region is the region where the engine load is less than or equal to the first preset load. A target region is determined from the plurality of regions based on the current operating condition of the engine, including: Obtain the engine speed and the engine load; When the engine speed is less than the first preset speed and the engine load is greater than the first preset load, the first region is determined to be the target region; When the engine speed is greater than or equal to the first preset speed and the engine load is greater than the first preset load, the second region is determined as the target region; If the engine load is less than or equal to the first preset load, the third region is determined as the target region.

6. The method according to claim 5, characterized in that, The engine exhaust temperature control device includes a turbocharger, and after determining that the first region is the target region, the method further includes: The intake air volume of the turbocharger is controlled to be increased to a preset intake air volume.

7. The method according to claim 4, characterized in that, Determining the control strategy for the engine exhaust temperature control device corresponding to the target region includes: The control strategy of the engine exhaust temperature control device corresponding to the target region is determined according to the preset mapping table between the target region and the control strategy, and the target region and the control strategy correspond one-to-one.

8. The method according to claim 7, characterized in that, The engine exhaust temperature control device includes a first branch and a second branch. After determining the control strategy of the engine exhaust temperature control device corresponding to the target region according to a preset mapping table between the target region and the control strategy, the method further includes: When the target area is the first area, the control valve is controlled to open the first pipeline and close the first branch and the second branch; If the target area is the second area, control the control valve to open the first branch and close the first pipeline and the second branch; If the target area is the third area, the control valve is controlled to open the second branch and close the first pipeline and the first branch.

9. The method according to claim 4, characterized in that, The engine exhaust temperature control device includes a first branch and a second branch. After determining the control strategy of the engine exhaust temperature control device corresponding to the target area, the method further includes: When the exhaust temperature of the engine is greater than a preset temperature and a preset time has elapsed, and the engine speed is less than a first preset speed, the control valve is controlled to open the first pipeline and close the first branch and the second branch. When the exhaust temperature of the engine is greater than the preset temperature and the preset time has elapsed, and the engine speed is greater than or equal to the first preset speed, the control valve is controlled to open the first branch and close the first pipeline and the second branch. If the exhaust temperature of the engine is less than or equal to the preset temperature and the preset time has elapsed, the control valve is controlled to open the second branch and close the first pipeline and the first branch.

10. An engine exhaust temperature control system, characterized in that, include: The engine exhaust temperature control device according to any one of claims 1 to 3; The electronic control unit communicates with the engine exhaust temperature control device and is used to execute the engine exhaust temperature control method according to any one of claims 4 to 9.

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