A hybrid vehicle dedicated engine EGR durability verification method

Abstract

The application discloses a kind of hybrid power special engine EGR durability verification method, wherein, including the following steps: S1, control the engine to be measured in first operating condition and second operating condition between alternate operation;S2, control the engine to be measured in first operating condition and third operating condition between alternate operation;S3, control the engine to be measured in first operating condition and fourth operating condition between alternate operation;S4, control the engine to be measured in set speed, throttle is increased to set throttle position from the throttle position corresponding to first operating condition, and from the throttle position corresponding to first operating condition is reduced to measured throttle position;S5, repeat steps S1 to S4, so that the engine to be measured is continuously operated for 500-1000 hours;S6, in the process of above steps operation, every set time obtains engine external characteristic performance attenuation, fuel consumption change and nitrogen oxide emission;The application can verify the EGR durability of hybrid power special engine.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hybrid electric vehicles, in particular to a method for verifying EGR durability of a hybrid electric vehicle engine. BACKGROUND

[0002] EGR is one of the important means to reduce nitrogen oxide emissions. On the basis of EGR technology, cooling EGR technology cools high-temperature exhaust gas on the basis of EGR, reduces the intake temperature, and comprehensively improves the performance of the engine. However, as emission regulations become more stringent, the application range, frequency, and EGR rate of EGR in the entire engine MAP have increased, and the failure risks of EGR deformation, coking, and sticking have also increased. In traditional engine durability tests, EGR operating conditions account for a small proportion, and there is no need to verify the durability of EGR and EGR cooling systems.

[0003] However, the engine used for a hybrid electric system is mostly in a load state during operation, and is in the working range of EGR. Compared with traditional gasoline vehicles, the time of EGR participating in work is greatly improved. Therefore, for the engine used for a hybrid electric vehicle, the durability of EGR needs to be verified.

[0004] How to verify the durability of EGR on a hybrid electric vehicle engine is one of the important problems to be solved in the field. SUMMARY

[0005] The purpose of the present application is to provide a method for verifying the EGR durability of a hybrid electric vehicle engine to solve the problems in the prior art, which can verify the EGR durability of a hybrid electric vehicle engine.

[0006] The present application provides a method for verifying the EGR durability of a hybrid electric vehicle engine, comprising the following steps:

[0007] S1, controlling the test engine to alternately operate between a first operating condition and a second operating condition;

[0008] S2, controlling the test engine to alternately operate between the first operating condition and a third operating condition;

[0009] S3, controlling the test engine to alternately operate between the first operating condition and a fourth operating condition;

[0010] S4, controlling the test engine to maintain a set speed, increasing the throttle position from the throttle position corresponding to the first operating condition to a set throttle position, and decreasing the throttle position from the set throttle position to the throttle position corresponding to the first operating condition;

[0011] S5, repeating steps S1 to S4 to make the test engine continuously operate for 500-1000 hours;

[0012] S6, during the running of the above steps, acquiring the engine external characteristic performance attenuation, fuel consumption change and nitrogen oxide emission every set time;

[0013] Wherein, in the first working condition, the EGR is closed; in the second working condition, the third working condition and the fourth working condition, the EGR is opened.

[0014] The hybrid engine EGR durability verification method as described above, wherein, optionally, the step S1 comprises,

[0015] S11, controlling the to-be-tested engine to transition from the first working condition to the second working condition within a first time;

[0016] S12, controlling the to-be-tested engine to transition from the second working condition to the first working condition within a second time;

[0017] S13, repeating the step S11 and the step S12 for a first set number of times;

[0018] S14, controlling the to-be-tested engine to stably run at a speed corresponding to the second working condition for a third time;

[0019] S15, repeating the step S13 and the step S14 for a second set number of times;

[0020] S16, controlling the to-be-tested engine to switch to the first working condition.

[0021] The hybrid engine EGR durability verification method as described above, wherein, optionally, in the first working condition, the engine speed is a first speed, the throttle opening is maintained at a first speed, and the minimum throttle opening required to keep the EGR closed.

[0022] The hybrid engine EGR durability verification method as described above, wherein, optionally, the step S2 comprises,

[0023] S21, controlling the to-be-tested engine to transition from the first working condition to the third working condition within a first time;

[0024] S22, controlling the to-be-tested engine to transition from the third working condition to the first working condition within a second time;

[0025] S23, repeating the step S21 and the step S22 for a first set number of times;

[0026] S24, controlling the to-be-tested engine to stably run at a speed corresponding to the third working condition for a third time;

[0027] S25, repeating the step S23 and the step S24 for a second set number of times;

[0028] S26, controlling the to-be-tested engine to switch to the first working condition.

[0029] The hybrid-dedicated engine EGR durability verification method as described above, wherein, optionally, step S3 comprises,

[0030] S31, controlling the engine under test to transition from the first operating condition to a fourth operating condition within a first time,

[0031] S32, controlling the engine to transition from the fourth operating condition to the first operating condition within a second time;

[0032] S33, repeating step S31 and step S32 a first set number of times;

[0033] S34, controlling the engine under test to operate stably at a speed corresponding to the fourth operating condition for a third time;

[0034] S35, repeating step S33 and step S34 a second set number of times;

[0035] S36, controlling the engine under test to switch to the first operating condition.

[0036] The hybrid-dedicated engine EGR durability verification method as described above, wherein, optionally, step S4 comprises,

[0037] S41, controlling the engine under test to accelerate to a set speed at a throttle position corresponding to the first operating condition;

[0038] S42, maintaining the engine under test at the set speed and increasing the throttle opening to a set throttle position;

[0039] S43, maintaining the engine under test at the set speed and decreasing the throttle opening to the throttle position corresponding to the first operating condition;

[0040] S44, repeating step S42 and S43 a second set number of times;

[0041] S45, controlling the engine to operate stably at the set speed and the set throttle position for a third time;

[0042] S46, repeating step S44 and step S45 a second set number of times;

[0043] S47, controlling the engine under test to switch to the first operating condition.

[0044] The hybrid-dedicated engine EGR durability verification method as described above, wherein, optionally, the first time is 5 seconds, the second time is 10 seconds, and the third time is 60 seconds.

[0045] The hybrid engine EGR durability verification method as described above, wherein, optionally, the engine speed corresponding to the first working condition, the engine speed corresponding to the second working condition, the engine speed corresponding to the third working condition, the engine speed corresponding to the fourth working condition and the set speed are sequentially increased.

[0046] The hybrid engine EGR durability verification method as described above, wherein, optionally, in step S6, the time interval for obtaining the nitrogen oxide emission for judging whether the EGR has failed is 50 hours.

[0047] The hybrid engine EGR durability verification method as described above, wherein, optionally, in step S6, the engine external characteristic performance attenuation and the fuel consumption change are obtained for judging whether the engine has a failure other than the EGR.

[0048] Compared with the prior art, the engine multi-working condition alternating cycle test is designed, the frequent opening and closing of the EGR valve can be simulated, and the durability performance under the frequent action of the EGR can be tested. The verification process can be close to the actual use working condition of the hybrid power battery, and the failure mode of frequent opening and closing or coking can be fully verified.

[0049] Meanwhile, in the verification process, the steady state working condition is added, the EGR can be always opened under a larger EGR rate working condition, and the coking and failure of the EGR cooler after long-term operation of the EGR are mainly examined. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 is the overall step flow chart of the present application;

[0051] Figure 2 is the specific step flow chart of step S1 proposed by the present application;

[0052] Figure 3 is the specific step flow chart of step S2 proposed by the present application;

[0053] Figure 4 is the specific step flow chart of step S3 proposed by the present application;

[0054] Figure 5 is the specific step flow chart of step S4 proposed by the present application. DETAILED DESCRIPTION

[0055] The embodiments described below with reference to the drawings are exemplary and are only used to explain the present application, and cannot be explained as a limitation of the present application.

[0056] On traditional fuel vehicles, due to the less use time of EGR, it is not necessary to carry out durability and permanent test on EGR and EGR cooling system, but for hybrid electric vehicles, due to the frequent switching of engine start-stop, the EGR valve is frequently opened and closed, and when the engine of the hybrid electric vehicle is working, the engine speed often quickly reaches 3000 rpm, and in this state, it is just the working area of EGR, therefore, on the hybrid electric vehicle, the use time of EGR is much longer than that of the fuel vehicle, which is easy to cause EGR deformation, coking, jamming and other faults. Therefore, for the engine of the hybrid power system, it is necessary to carry out durability verification on EGR and EGR cooling system, therefore, the following solutions are proposed.

[0057] Embodiment 1

[0058] Please refer to Figures 1 to 5 The embodiment discloses a kind of special engine EGR durability verification methods of hybrid power, this method is carried out on engine test bench.Engine is connected with dynamometer, by adjusting the resistance torque of dynamometer, the change of engine load can be realized.Specifically, it includes the following steps:

[0059] S1, control the engine to be tested to run between first condition and second condition alternately.In specific implementation, the first condition is the condition that EGR is closed, and the second condition is the condition that EGR is opened, when the engine to be tested runs between first condition and second condition alternately, EGR will be switched back and forth between closing and starting.Thus simulating the frequent switching of EGR.In specific implementation, the first condition can be set to keep the engine speed at 1000 rpm, while keeping the minimum throttle required for EGR to be closed, the throttle corresponding to the first condition can be generally controlled between 5% and 15%, such as 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% and the like.In specific selection, the minimum throttle required for EGR to be closed when the engine speed is 1000 rpm is used.For different models of engine, the data can be different.

[0060] Please refer to Figure 2 In specific implementation, the step includes the following specific steps,

[0061] S11, control the to-be-tested engine to transition from the first working condition to the second working condition within a first time; in a specific implementation, the second working condition is set to an engine speed of 2000 rpm and an accelerator opening degree of 40%, and in this state, the EGR is open; in a specific implementation, the to-be-tested engine is controlled to transition from the first working condition to the second working condition within the first time, so that the process of the EGR valve from being closed to being open. In actual application, it is a common working condition that the engine of the hybrid vehicle is started and quickly raised to 2000 rpm, 3000 rpm, 4000 rpm or even higher. By transitioning the to-be-tested engine from the first working condition to the second working condition, the EGR from being closed to being open under the condition that the engine rotates at a low speed can be realized. In a specific implementation, the first time is 5 seconds, and according to different engine models and performances, the first time can also be set to a range of 3-8 seconds, such as 4 seconds, 5 seconds, 6 seconds, 7 seconds, etc.

[0062] S12, control the to-be-tested engine to transition from the second working condition to the first working condition within a second time; that is, in a specific implementation, the to-be-tested engine is controlled to transition from the second working condition to the first working condition by reducing the accelerator to the accelerator corresponding to the first working condition, and adjusting the resistance torque of the dynamometer as needed. In this process, the EGR is switched from the working state to the closed state. Thus, the EGR closing condition under the condition that the engine rotates at 2000 rpm to 1000 rpm is realized. In a specific implementation, the second time is 10 seconds, and according to different engine models and performances, the first time can also be set to a range of 8-12 seconds, such as 9 seconds, 10 seconds, 11 seconds, etc.

[0063] S13, repeat steps S11 and S12 a first set number of times. Each time steps S11 and S12 are repeated, the EGR closing-opening-closing caused by switching between 2000 rpm and 1000 rpm is realized once. In this step, S11 and S12 are repeated 9 times, that is, the first set number of times is selected to be 9 times. For the setting of the set number of times, the proportion of engine low-speed and idle-speed switching in actual operation and the total time length designed in this test need to be considered comprehensively.

[0064] S14, control the to-be-tested engine to stably run at the speed corresponding to the second working condition for a third time; that is, control the to-be-tested engine to stably run at a speed of 2000 rpm for a third time. In implementation, the third time is 60 seconds. Controlling the to-be-tested engine to stably run at the speed corresponding to the second working condition for the third time is to simulate the actual running state of the to-be-tested engine at a speed of 2000 rpm, and facilitate the setting of a detection point to realize the detection of the engine, the EGR, and the EGR cooling system during running. The third time is preferably 60 seconds. The selection of the third time needs to meet the requirements of stable running of the engine, sufficient detection, and the running time ratio being sufficient to simulate the actual running state. In implementation, the selection range of the third time can be widened to 30 to 90 seconds according to actual needs.

[0065] S15, repeat steps S13 and S14 for a second set number of times; in implementation, the second set number of times can be selected to be 3 to 8, such as 4, 5, 6, 7, etc., according to actual conditions. In implementation, the purpose of repeating steps S13 and S14 is to repeat the state of the EGR in the foregoing steps S11, S12, and S14 to achieve the purpose of rapid measurement of durability.

[0066] S16, control the to-be-tested engine to switch to the first working condition; that is, control the to-be-tested engine to switch to a state in which the speed is 1000 rpm and the throttle opening degree is 10%. The purpose of this step is to facilitate the next step to continuously perform the entire test without interruption.

[0067] S2, control the to-be-tested engine to alternately run between the first working condition and a third working condition. In implementation, the third working condition refers to a state in which the engine speed is 3000 rpm and the throttle is at 40%, and in this state, the EGR is opened.

[0068] Please refer to Figure 3 In implementation, this step further includes the following specific steps:

[0069] S21, control the to-be-tested engine to transition from the first working condition to the third working condition within a first time; in implementation, control the to-be-tested engine to transition from the first working condition to the third working condition within the first time, so as to realize the process of the EGR valve from being closed to being opened. In actual application, it is common for the engine of a hybrid vehicle to be started and quickly raised to 2000 rpm, 3000 rpm, or 4000 rpm. By transitioning the to-be-tested engine from the first working condition to the third working condition, the EGR can be opened from being closed under the condition of medium-speed rotation of the engine. In implementation, the first time is 5 seconds, and according to different engine models and performance, the first time can also be set to be within a range of 3 to 8 seconds, such as 4 seconds, 5 seconds, 6 seconds, 7 seconds, etc.

[0070] S22, control the to-be-tested engine to transit from the third working condition to the first working condition within a second time; that is, in specific implementation, by reducing the throttle to the throttle corresponding to the first working condition, and adjusting the resistance torque of the dynamometer as needed, the to-be-tested engine is transited from the third working condition to the first working condition. In this process, the EGR is switched from the working state to the closed state. Thus, the EGR closing condition in the case that the engine rotates at a low speed to an idle speed is realized. In specific implementation, the second time is 10 seconds, and according to different engine models and performances, the first time can also be set to be in the range of 8-12 seconds, such as 9 seconds, 10 seconds, 11 seconds, etc.

[0071] S23, repeat the step S21 and the step S22 for a first set number of times; each time the step S21 and the step S22 are repeated, the EGR closing-opening-closing caused by the switching at the medium speed and the idle speed is generated once. In this step, the step S21 and the step S22 are repeated 9 times, that is, the first set number of times is selected to be 9 times. For the setting of the set number of times, the proportion of the switching at the medium speed and 1000 rpm in the actual operation and the total time length designed in this test are comprehensively considered, and the set number of times can also be 6 times, 7 times, 8 times, 10 times, 11 times, etc.

[0072] S24, control the to-be-tested engine to stably operate at the third working condition for a third time; that is, control the to-be-tested engine to stably operate at the speed corresponding to the second working condition for the third time, and in implementation, the third time is 60 seconds. Controlling the to-be-tested engine to stably operate at the speed corresponding to the second working condition for the third time is to simulate the actual operation state of the to-be-tested engine at 3000 rpm, on the one hand, and to facilitate the setting of detection points to realize the detection of the engine, the EGR and the EGR cooling system in the operation process, on the other hand. The third time is preferably 60 seconds, and the selection of the third time needs to meet the requirements of stable operation of the engine, sufficient detection and the proportion of the operation time being enough to simulate the actual operation. In implementation, the selection range of the third time can be widened to 30-90 seconds according to needs.

[0073] S25, repeat the step S23 and the step S24 for a second set number of times; in specific implementation, the second set number of times in this step can be selected to be 3-8 times according to actual conditions, such as 4 times, 5 times, 6 times, 7 times, etc. In specific implementation, the purpose of repeating the step S23 and the step S24 is to repeat the states of the EGR in the foregoing steps S21, S22 and S24 to achieve the purpose of rapid measurement of durability.

[0074] S26, control the to-be-tested engine to switch to the first working condition; that is, control the to-be-tested engine to switch to the state of 1000 rpm and 10% throttle opening. The purpose of this step is to facilitate the step 3 to be performed, so that the whole test is continuously and uninterruptedly performed, and the EGR is in the closed state through this step.

[0075] S3, controlling the to-be-tested engine to alternately run between the first working condition and the fourth working condition; in specific implementation, the fourth working condition refers to that the engine speed is 4000 rpm and the throttle opening degree is at 40%, and in this state, the EGR is opened.

[0076] Please refer to Figure 4 , in specific implementation, the step S3 comprises the following steps:

[0077] S31, controlling the to-be-tested engine to transition from the first working condition to the fourth working condition within a first time; in specific implementation, the to-be-tested engine is controlled to transition from the first working condition to the fourth working condition within the first time, so that the process of the EGR valve from being closed to being opened. In actual application, it is a common working condition that the engine of the hybrid vehicle is started and then quickly promoted to 2000 rpm, 3000 rpm or 4000 rpm. By transitioning the to-be-tested engine from the first working condition to the fourth working condition, the EGR from being closed to being opened in the case of high engine speed can be realized. In specific implementation, the first time is 5 seconds, and according to different engine models and performances, the first time can also be set to be within a range of 3-8 seconds, such as 4 seconds, 5 seconds, 6 seconds, 7 seconds, etc.

[0078] S32, controlling the engine to transition from the fourth working condition to the first working condition within 10 seconds; that is, in specific implementation, the to-be-tested engine is transitioned from the fourth working condition to the first working condition by reducing the throttle corresponding to the first working condition and adjusting the resistance torque of the dynamometer as needed. In this process, the EGR is switched from the working state to the closed state. Thus, the EGR closing condition in the case of the engine being promoted from high speed to 1000 rpm can be realized. In specific implementation, the second time is 10 seconds, and according to different engine models and performances, the first time can also be set to be within a range of 8-12 seconds, such as 9 seconds, 10 seconds, 11 seconds, etc.

[0079] S33, repeating the step S31 and the step S32 for a first set number of times; each time the step S31 and the step S32 are repeated, the EGR closing-opening-closing caused by the switching between the medium speed and the idle speed can be generated once. In this step, S31 and S32 are repeated 9 times, that is, the first set number of times is selected to be 9 times. The set number of times is set by comprehensively considering the proportion of the switching between the high engine speed and the 1000 rpm in actual operation and the total time length designed in this test, etc.

[0080] S34, control the to-be-tested engine to stably run at the engine speed corresponding to the fourth working condition for a third time; that is, control the to-be-tested engine to stably run at a speed of 4000 rpm for a third time. In implementation, the third time is 60 seconds. Controlling the to-be-tested engine to stably run at the speed corresponding to the fourth working condition for the third time is to simulate the actual running state of the to-be-tested engine at a speed of 4000 rpm, and facilitate the setting of a detection point to realize the detection of the engine, the EGR, and the EGR cooling system during running. The third time is preferably 60 seconds. The selection of the third time needs to meet the requirements of stable running of the engine, sufficient detection, and the running time ratio being sufficient to simulate the actual running state. In implementation, the selection range of the third time can be widened to 30 to 90 seconds according to actual needs.

[0081] S35, repeat step S33 and step S34 for a second set number of times; in implementation, the second set number of times in this step can be selected to be 3 to 8, such as 4, 5, 6, 7, and the like, according to actual conditions. In implementation, the purpose of repeating step S23 and step S24 is to repeat the state of the EGR in the foregoing steps S21, S22, and S24 to achieve the purpose of rapid durability measurement.

[0082] S36, control the to-be-tested engine to switch to the first working condition; that is, control the to-be-tested engine to switch to a state in which the speed is 1000 rpm and the throttle opening degree is 10%. The purpose of this step is to facilitate the performance of step 4 to continuously perform the entire test without interruption, and the EGR is in a closed state through this step.

[0083] S4, control the to-be-tested engine to keep at a set speed and cyclically control the throttle to increase and then decrease; that is, control the to-be-tested engine to keep at a set speed, increase the throttle from the throttle position corresponding to the first working condition to a set throttle position, and decrease the throttle from the set throttle position to the throttle position corresponding to the first working condition. In implementation, the set speed in this embodiment is 4500 rpm, and the set throttle opening degree is 40%. In the case where the throttle opening degree is 40% and the speed is 4500 rpm, the EGR is opened.

[0084] In implementation, this step further includes the following specific steps:

[0085] S41, control the to-be-tested engine to accelerate to a set speed at the throttle position corresponding to the first working condition; this step is to quickly reach the initial working condition of step S42. In implementation, the speed can also be directly adjusted to the set speed from step S36, and the throttle position is the throttle opening degree position corresponding to the first working condition.

[0086] S42, maintain the engine to be tested at the set speed, and increase the throttle opening to the set throttle position; in implementation, the duration of this step is set to 5 seconds, i.e., the throttle opening is increased from the throttle opening position corresponding to the first working condition to the set throttle position within 5 seconds. According to different actual conditions, it can also be set to 3 seconds, 4 seconds, 6 seconds, 7 seconds, etc.

[0087] S43, maintain the engine to be tested at the set speed, and decrease the throttle opening to the throttle position corresponding to the first working condition; in implementation, the duration of this step is set to 5 seconds, i.e., the throttle opening is decreased from the set throttle position to the throttle position corresponding to the first working condition within 5 seconds. According to different actual conditions, it can also be set to 3 seconds, 4 seconds, 6 seconds, 7 seconds, etc.

[0088] In step S4, in implementation, the set speed can also be 4200 rpm to 4800 rpm, such as 4300 rpm, 4400 rpm, 4600 rpm, 4700 rpm, etc. That is, when the engine speed is set at a high speed, the throttle opening is first increased and then decreased. For a hybrid vehicle, the engine is often quickly pulled up to a high speed when working to achieve high efficiency, and this working state is also a frequent EGR working area. Steps S42 and S43 can simulate this state, so that the durability test is closer to the use process.

[0089] S44, repeat steps S42 and S43 for a first set number of times; in implementation, the second set number of times can be selected to be 3 to 8 times according to actual conditions, such as 4 times, 5 times, 6 times, 7 times, etc.

[0090] S45, control the engine to stably operate at the set speed and the set throttle for a third time. In implementation, the third time is preferably 60 seconds, and the selection of the third time needs to meet the requirements of stable engine operation, sufficient detection, and the running time ratio being sufficient to simulate actual operation. In implementation, the selection range of the third time can be widened to 30 to 90 seconds according to needs.

[0091] S46, the second set number of times of steps S44 and S45; in this step, steps S44 and S45 are repeated 9 times, i.e., the first set number of times is selected as 9 times. For the setting of the set number of times, factors such as the proportion of the switching between the medium engine speed and the 1000 rpm speed in actual operation and the total duration designed in the test are comprehensively considered, and the set number of times can also be 6 times, 7 times, 8 times, 10 times, 11 times, etc. S47, the control of switching the engine under test to the first working condition. That is, the engine under test is controlled to switch to the state of 1000 rpm of the engine speed and 10% of the throttle opening. The purpose of this step is to facilitate the next cycle to be performed, so that the entire test is continuously and uninterruptedly performed, and the EGR is in the closed state through this step.

[0092] In a specific implementation, the engine speed corresponding to the first working condition, the engine speed corresponding to the second working condition, the engine speed corresponding to the third working condition, the engine speed corresponding to the fourth working condition, and the set speed are sequentially increased. In this way, the corresponding EGR working state and the EGR opening and closing state under different engine speeds are sequentially verified.

[0093] S5, repeating steps S1 to S4 to continuously operate the engine under test for 500-1000 hours. That is, steps S1 to S4 are repeated as one large cycle, and in this process, the engine under test is continuously operated for 500-1000 hours to achieve the purpose of the durability test.

[0094] The above steps S1 to S4 are the setting process of the engine operation. In order to obtain the verification result and the influence of the engine itself on the test result, the method further sets the following steps.

[0095] S6, in the process of the above steps, the engine external characteristic performance attenuation, fuel consumption change, and nitrogen oxide emission are obtained every set time.

[0096] Step S6 includes two parts, nitrogen oxide emission is obtained every 50 hours, and the detection of nitrogen oxide emission is carried out under the condition that the engine is stably operated in the specific implementation. In the specific implementation, the nitrogen oxide emission obtained each time should include the nitrogen oxide emission when the engine speed is stably 2000 rpm, 3000 rpm, 4000 rpm and 4500 rpm. That is, the detection of nitrogen oxide each time should be concentrated in steps S14, S24, S34 and S45 in one large cycle. The nitrogen oxide emission is used to determine whether the EGR has failed, and in this process, whether the increase of nitrogen oxide is greater than 10% compared with the first large cycle at the beginning of the test is determined. If the detection results of each time are not all increased by 10% compared with the detection results of the first large cycle before the test is completed, it is indicated that the durability requirement is met. If the increase of nitrogen oxide is greater than 10% once or more, it is indicated that the durability requirement is not met, and the earlier the time of occurrence, the worse the EGR durability. In the verification process, since the accurate premise of verifying the EGR and the EGR cooling is that the engine is fault-free, the engine fault needs to be monitored during the verification. This involves another part of step S6, engine external characteristic performance attenuation and oil consumption change are obtained every 100 hours. In the specific implementation, the detection of external characteristic performance attenuation and oil consumption change can be calculated by other monitorable parameters and carried out under the condition that the engine is stably operated. In the specific implementation, the external characteristic performance attenuation and oil consumption change each time should include the external characteristic performance attenuation and oil consumption change when the engine speed is stably 2000 rpm, 3000 rpm, 4000 rpm and 4500 rpm. That is, each detection should be concentrated in steps S14, S24, S34 and S44 in one large cycle.

[0097] The external characteristic performance attenuation and oil consumption change are used to represent the state of the engine and to determine whether the engine has a fault other than the EGR. Compared with the detection results of the first large cycle, the external characteristic performance attenuation should be less than 5%, and the oil consumption change should also be less than 5%. If the external characteristic performance attenuation in a certain measurement is greater than 5% or the oil consumption change is greater than 5%, it is indicated that the engine itself has a fault, and the verification of the EGR and the EGR cooling system has no meaning, and the test needs to be re-performed.

[0098] In specific implementation, the throttle corresponding to the second working condition, the throttle corresponding to the third working condition, and the throttle corresponding to the fourth working condition are all the same, and can be 35-50%. In specific implementation, 40% can be selected. The throttle is selected according to the EGR opening when the engine speed is 2000 rpm, 3000 rpm, 4000 rpm, and 4500 rpm at the throttle opening.

[0099] It should be noted that in steps S14, S24, S34, and S44, the throttle required to maintain stable engine operation is often less than the throttle when switching to the corresponding working condition.

[0100] After the engine operation ends, the wear and tear of the EGR valve, the carbon deposition, and the coking of the EGR cooler are evaluated to determine whether the durability of the EGR and the EGR cooler meets the requirements, and the EGR maintenance mileage is set.

[0101] Example 2

[0102] This example is an EGR durability test for a certain type of hybrid engine according to the method provided in Example 1.

[0103] The EGR special durability verification method for the hybrid engine of the present application is composed of transient working conditions with frequent opening and closing of the EGR and steady-state working conditions with large EGR opening of the EGR keeping constant opening, covering the user's usage habits, and verifying the durability and reliability of the frequent opening and closing of the EGR valve and the long-term operation of the EGR cooler, respectively.

[0104] The engine speed is not fixed, covering all the speed ranges of the hybrid engine. The transient working condition makes the EGR valve act frequently through variable throttle and variable speed, and the steady-state working condition makes the EGR run constantly through constant speed and constant throttle, which fully runs the EGR under various conditions, effectively improves the EGR operation ratio, and is suitable for more types of hybrid engine durability verification for users. The present application will be further described in conjunction with specific examples:

[0105] On the M20A engine matched with the HEV vehicle, the test procedures in the following table are determined in combination with the universal characteristic MAP, and the engine is run for 570 hours, which is equivalent to 250,000 kilometers of user equivalent use. This example describes the M20A matched with the hybrid power as a whole, but the present application is not limited to this form, and other models of tests can also be used.

[0106] Table 1 is a test process of one cycle, and in actual application, the contents in Table 1 are repeated continuously for 570 hours.

[0107] Table 1

[0108]

[0109] The test automatic control program is set according to Table 1, the engine is operated according to the established working condition cycle, and the EGR is fully operated through the variable speed and variable throttle and the constant speed and constant throttle, so that the operation intensity in a short time reaches the long-term use of the user. The wear of the EGR valve and the coking of the EGR cooler are evaluated, and the maintenance mileage and specification of the EGR valve are determined, and the improvement requirements are determined.

[0110] Through the contents of the above-mentioned embodiment 1 and embodiment 2, the verification method proposed by the application can perform durability verification under transient working condition and steady working condition. The main purpose of the transient working condition is to frequently open and close the EGR valve, mainly to test the durability performance of the frequent action of the EGR. The steady working condition mainly keeps the EGR open under a larger EGR rate working condition, mainly to test the coking and failure of the EGR cooler after long-term operation of the EGR. Using this method, the EGR reaches the effect of long-term use of the user in a short time, so that the durability of the product can be quickly evaluated in the development engineering, and the effect is remarkable. Not only the durability and reliability of the frequent opening and closing of the EGR valve can be fully tested, but also the coking, carbon deposition and other failure modes of the EGR under long-term operation at a larger opening degree can be fully verified.

[0111] The above embodiment according to the drawings details the structure, features and effect of the application. The above description is only the preferred embodiment of the application, but the application is not limited by the drawings. Any changes or modifications made in accordance with the concept of the application, or equivalent embodiments with equivalent changes, are still within the scope of the application.

Claims

1. A hybrid-dedicated engine EGR durability verification method characterized by: The method comprises the following steps: S1, controlling the to-be-tested engine to alternately run between a first working condition and a second working condition; S2, controlling the to-be-tested engine to alternately run between the first working condition and a third working condition; S3, controlling the to-be-tested engine to alternately run between the first working condition and a fourth working condition; S4, controlling the to-be-tested engine to keep at a set rotating speed, increasing the throttle from a throttle position corresponding to the first working condition to a set throttle position, and decreasing the throttle from the set throttle position to the throttle position corresponding to the first working condition; S5, repeating steps S1 to S4 to make the to-be-tested engine continuously run for 500-1000 hours; S6, during the running of the above steps, acquiring the performance attenuation of the engine external characteristic, the fuel consumption change and the nitrogen oxide emission every set time; wherein, in the first working condition, the EGR is closed; in the second working condition, the third working condition and the fourth working condition, the EGR is opened; Step S1 comprises, S11, controlling the to-be-tested engine to transition from the first working condition to the second working condition within a first time; S12, controlling the to-be-tested engine to transition from the second working condition to the first working condition within a second time; S13, repeating steps S11 and S12 for a first set number of times; S14, controlling the to-be-tested engine to stably run at a rotating speed corresponding to the second working condition for a third time; S15, repeating steps S13 and S14 for a second set number of times; S16, controlling the to-be-tested engine to switch to the first working condition.

2. The hybrid-dedicated engine EGR durability verification method according to claim 1, characterized by: In the first working condition, the engine rotating speed is a first rotating speed, the throttle opening is a minimum throttle opening required for maintaining the first rotating speed and keeping the EGR closed.

3. The hybrid-dedicated engine EGR durability verification method according to claim 1, characterized by: Step S2 comprises, S21, controlling the to-be-tested engine to transition from the first working condition to the third working condition within a first time; S22, controlling the to-be-tested engine to transition from the third working condition to the first working condition within a second time; S23, repeating steps S21 and S22 for a first set number of times; S24, controlling the to-be-tested engine to stably run at a rotating speed corresponding to the third working condition for a third time; S25, repeating steps S23 and S24 for a second set number of times; S26, controlling the to-be-tested engine to switch to the first working condition.

4. The hybrid-dedicated engine EGR durability verification method according to claim 3, characterized by: Step S3 comprises, S31, controlling the to-be-tested engine to transition from the first working condition to the fourth working condition within a first time; S32, controlling the to-be-tested engine to transition from the fourth working condition to the first working condition within a second time; S33, repeating steps S31 and S32 for a first set number of times; S34, controlling the to-be-tested engine to stably run at a rotating speed corresponding to the fourth working condition for a third time; S35, repeating steps S33 and S34 for a second set number of times; S36, controlling the to-be-tested engine to switch to the first working condition.

5. The hybrid-dedicated engine EGR durability verification method according to claim 4, characterized by: Step S4 comprises, S41, controlling the to-be-tested engine to accelerate to a set rotating speed at a throttle position corresponding to the first working condition; S42, maintaining the to-be-tested engine at the set rotating speed and increasing the throttle opening to a set throttle position; S43, maintaining the to-be-tested engine at the set rotating speed and decreasing the throttle opening to the throttle position corresponding to the first working condition; S44, repeating steps S42 and S43 for a second set number of times; S45, controlling the to-be-tested engine to stably run at the set rotating speed and the set throttle position for a third time; S46, repeating steps S44 and S45 for a second set number of times; S47, control the to-be-tested engine to switch to the first working condition.

6. The hybrid-dedicated engine EGR durability verification method according to claim 5, characterized by: The first time is 5 seconds, the second time is 10 seconds, and the third time is 60 seconds.

7. The hybrid-dedicated engine EGR durability verification method according to claim 5, characterized by: The engine speed corresponding to the first working condition, the engine speed corresponding to the second working condition, the engine speed corresponding to the third working condition, the engine speed corresponding to the fourth working condition, and the set speed are sequentially increased.

8. The hybrid-dedicated engine EGR durability verification method according to any one of claims 1 to 7, characterized by: In step S6, the time interval for obtaining the nitrogen oxide emission is 50 hours, and the nitrogen oxide emission is used to judge whether the EGR has failed.

9. The hybrid-dedicated engine EGR durability verification method according to claim 8, characterized by: In step S6, the engine external characteristic performance attenuation and the oil consumption change are used to judge whether the engine has a fault other than the EGR.

Images