Load sudden change control method for coping with constant rotating speed control mode of diesel engine

Abstract

The invention discloses a sudden load change control method for a constant rotating speed control mode of a diesel engine, which relates to a diesel engine control technology and comprises the following steps: acquiring a required torque of external equipment, and correcting the required torque through a required torque correction coefficient to obtain a final required torque; the current rotating speed of the diesel engine is read, and the pre-control target fuel injection quantity of the diesel engine is calibrated according to the final required torque and the current rotating speed; the required rotating speed of external equipment is obtained, the PID target fuel injection quantity is calculated according to the required rotating speed and the current rotating speed, and the pre-control target fuel injection quantity and the PID target fuel injection quantity are added to obtain the final fuel injection quantity; and according to the real-time working condition data of the diesel engine, the smoking limiting oil quantity is obtained, and according to the smoking limiting oil quantity, the final oil injection quantity is analyzed and judged to determine the final required oil injection quantity. According to the method, the target fuel injection quantity can be accurately calculated, and the harsh requirements of improving the constant-rotating-speed control transient response time of the diesel engine and reducing the rotating speed overshoot rate are met.

Description

Technical Field

[0001] The invention relates to a diesel engine control technology, and more specifically, to a load mutation control method for a diesel engine constant speed control mode. Background Art

[0002] As a widely used power equipment, diesel engines play an important role in the fields of industry, agriculture, transportation, etc. In practical applications, diesel engines often face sudden load changes. For example, in power generation and range extenders, the oil-electric switching and oil-electric output power changes are particularly obvious, and the magnitude of the change is large. When the load suddenly changes, if the diesel engine cannot respond in time, there is a problem of insufficient output power or even interruption; and increasing the response time of the diesel engine will cause the problem of speed overshoot. It is difficult to balance the two. Therefore, there is an urgent need for a load mutation control method that can cope with the constant speed control mode of the diesel engine. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a load mutation control method for a diesel engine constant speed control mode in view of the deficiencies in the prior art, so as to achieve the stringent requirements of improving the transient response time of the diesel engine constant speed control and reducing the speed overshoot rate.

[0004] The method for load mutation control in a constant speed control mode of a diesel engine of the present invention obtains the required torque of an external device, and corrects the required torque by a required torque correction coefficient to obtain a final required torque; reads the current speed of the diesel engine, and calibrates the pre-control target injection amount of the diesel engine according to the final required torque and the current speed;

[0005] The required speed of the external device is obtained, a PID target fuel injection amount is calculated according to the required speed and the current speed, and the pre-control target fuel injection amount and the PID target fuel injection amount are added to obtain a final fuel injection amount; the smoke limit fuel amount is obtained according to the real-time operating condition data of the diesel engine, and the final fuel injection amount is analyzed and judged according to the smoke limit fuel amount to determine the final required fuel injection amount.

[0006] As a further improvement, the method for determining the final required fuel injection amount is:

[0007] The smoke-limited fuel amount is compared with the final fuel injection amount. If the final fuel injection amount is less than the smoke-limited fuel amount, the final fuel injection amount is used as the final required fuel injection amount; otherwise, the smoke-limited fuel amount is used as the final required fuel injection amount.

[0008] As a further improvement, the calculation method of the PID target injection amount is:

[0009] The required speed and the current speed are subtracted to obtain a speed difference, and the speed difference is multiplied by a proportional coefficient of a P component to obtain a required fuel volume of the P component;

[0010] Multiplying the integral value of the speed difference by the proportionality coefficient of the I component to obtain the required oil quantity of the I component;

[0011] Multiplying the differential value of the speed difference by the proportional coefficient of the D component to obtain the required oil quantity of the D component;

[0012] The required fuel quantity of the I component is frozen, and the required fuel quantity of the P component, the frozen required fuel quantity of the I component, and the required fuel quantity of the D component are summed to obtain a PID target fuel injection quantity.

[0013] Furthermore, the method of freezing the required oil quantity of the component I is as follows:

[0014] When the required oil quantity of the I component is greater than the set I component oil quantity threshold, the required oil quantity of the I component at the previous moment is locked as the current required oil quantity of the I component; when the required oil quantity of the I component is less than the set I component oil quantity threshold, the required oil quantity of the I component at the next moment is locked as the current required oil quantity of the I component.

[0015] As a further improvement, the final required torque is the product of the required torque correction coefficient and the required torque.

[0016] As a further improvement, the method for obtaining the required torque correction coefficient is:

[0017] A plurality of real-time performance data of the diesel engine is obtained, and a torque correction coefficient corresponding to the real-time performance data is searched through a preset performance data-torque correction coefficient curve according to the real-time performance data, and all the torque correction coefficients are summed to obtain a required torque correction coefficient.

[0018] As a further improvement, a first timing period is set; within the first timing period, if the required torque of the external device cannot be obtained, a fault message is reported, and the current required torque is set to the last correctly received required torque.

[0019] Furthermore, if the required rotation speed of the external device cannot be obtained within the first timing period, a fault message is reported, and the current required rotation speed is set to the last correctly received required rotation speed.

[0020] Beneficial Effects

[0021] The advantages of the present invention are: the required speed and required torque are informed in advance by an external load device, and the target injection amount, that is, the final required injection amount, is accurately calculated based on the required speed and required torque, thereby achieving the stringent requirements of improving the transient response time of the constant speed control of the diesel engine and reducing the speed overshoot rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic flow chart of the control method of the present invention;

[0023] Figure 2 It is a schematic diagram of the calculation process of the required torque correction coefficient of the present invention;

[0024] Figure 3 It is a schematic diagram of the calculation process of the required oil quantity of the P component of the present invention;

[0025] Figure 4 This is a schematic diagram of the calculation process of the required oil quantity of component I of the present invention;

[0026] Figure 5 It is a schematic diagram of the calculation process of the required oil quantity of the D component of the present invention;

[0027] Figure 6 It is a schematic diagram of the PID target injection quantity calculation process of the present invention. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with the embodiments, but it does not constitute any limitation to the present invention. Any limited number of modifications made by anyone within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0029] See also Figure 1-Figure 6 The present invention provides a method for controlling sudden load changes in a constant speed control mode of a diesel engine. The specific process of the method is as follows:

[0030] Step 1: Program start.

[0031] Step 2: Read the required torque of the external device regularly through vehicle Ethernet, CAN communication, CANFD communication, etc., and output the required torque to the next step. If the required torque information of the external device cannot be read within the set first timing time, a fault will be reported and the required torque will be set to the last correctly received required torque to prevent torque mutations from causing safety accidents.

[0032] Step 3: Read the current speed of the diesel engine in real time. The reading method is not limited and is not within the scope of consideration of this invention.

[0033] Step 4: Read the required speed of the external device regularly through vehicle Ethernet, CAN communication, CANFD communication, etc., and output the required speed to the next step. If the required speed information of the external device cannot be read within the first timing period, a fault will be reported, and the required speed will be set to the last correctly received required speed to prevent safety accidents caused by sudden torque changes.

[0034] Step 5: After performing first-order low-pass filtering and limiting filtering on the required speed output in step 4, the filtered required speed is output for subsequent use. Among them, the time constant and other calibrable parameters of the first-order low-pass filtering algorithm are determined according to the actual debugging results, and the maximum amplitude and minimum amplitude of the calibrable parameters of the limiting filtering algorithm are determined according to the actual debugging results.

[0035] Step 6: Read the current diesel engine water temperature, ambient pressure and other real-time performance data in real time. These parameters are inputs of other control modules of the diesel engine, and the reading method is not limited, which is not within the scope of this invention.

[0036] Step 7: Calculate the required torque correction coefficient by reading the real-time performance data that affect the diesel engine performance, such as the ambient pressure and diesel engine water temperature. Specifically, the torque correction coefficient is set as a one-dimensional search curve, the X-axis of the curve is the real-time performance data such as the ambient pressure or diesel engine water temperature, and the Y-axis is the torque correction coefficient calculated corresponding to the X-axis. After finding each real-time performance data, all the torque correction coefficients are summed to obtain the required torque correction coefficient.

[0037] For example, Figure 2 As shown, the correction coefficient EnvP_facTrqDem based on the ambient pressure and the correction coefficient CengDsT_facTrqDem based on the diesel engine water temperature are summed to obtain the required torque correction coefficient.

[0038] Step 8: Multiply the required torque correction coefficient calculated in step 7 by the required torque in step 2 to obtain the final required torque.

[0039] Step 9: After performing first-order low-pass filtering and limiting filtering on the current speed in step 3, the filtered current speed is output for subsequent use. Among them, the time constant and other calibrable parameters of the first-order low-pass filtering algorithm are determined according to the actual debugging results, and the maximum amplitude and minimum amplitude of the calibrable parameters of the limiting filtering algorithm are determined according to the actual debugging results.

[0040] Step 10: Subtract the required speed after filtering in step 5 from the current speed after filtering in step 9 to obtain the speed difference. Figure 3As shown, the speed difference is multiplied by the proportional coefficient of the P component to obtain the required oil volume of the P component. Among them, the proportional coefficient of the P component is obtained by searching a one-dimensional curve with the speed difference as the X-axis and the proportional coefficient of the P component as the Y-axis, and the proportional coefficient of the P component is determined according to the actual debugging results.

[0041] like Figure 4 As shown, the integral value of the speed difference is multiplied by the proportional coefficient of the I component to calculate the required oil volume of the I component. The proportional coefficient of the I component is obtained by searching a one-dimensional curve with the speed difference as the X-axis and the proportional coefficient of the I component as the Y-axis, and the proportional coefficient of the I component is determined according to the actual debugging results.

[0042] like Figure 5 As shown, the integral value of the speed difference is multiplied by the proportional coefficient of the D component to calculate the required oil volume of the D component. The proportional coefficient of the D component is obtained by searching a one-dimensional curve with the speed difference as the X-axis and the proportional coefficient of the D component as the Y-axis, and the proportional coefficient of the D component is determined according to the actual debugging results.

[0043] In addition, the demanded fuel quantity of component I needs to go through a freezing algorithm, the principle of which is: when the demanded fuel quantity of component I is greater than the set fuel quantity threshold of component I, the demanded fuel quantity of component I at the previous moment is locked as the current demanded fuel quantity of component I; when the demanded fuel quantity of component I is less than the set fuel quantity threshold of component I, the demanded fuel quantity of component I at the next moment is locked as the current demanded fuel quantity of component I.

[0044] like Figure 6 As shown, the required fuel quantity of the P component, the value of the required fuel quantity of the I component after the freezing algorithm, and the required fuel quantity of the D component are finally added to obtain the PID target injection quantity.

[0045] Step 11: After performing first-order low-pass filtering and limiting filtering on the final required torque in step 8, the filtering result is output to the next step. Among them, the time constant and other calibrable parameters of the first-order low-pass filtering algorithm are determined according to the actual debugging results, and the maximum amplitude and minimum amplitude of the calibrable parameters of the limiting filtering algorithm are determined according to the actual debugging results.

[0046] Step 12: Perform a two-dimensional curve query based on the final required torque output from step 11 and the current speed from step 9 to obtain the pre-control target injection amount. The two-dimensional curve has the torque as the X-axis, the current speed as the Y-axis, and the pre-control target injection amount as the Z-axis. The two-dimensional curve is calibrated by a diesel engine test bench.

[0047] Step 13: After performing first-order low-pass filtering and limiting filtering on the PID target injection amount output in step 10, the filtering result is output to the next step. Among them, the time constant and other calibrable parameters of the first-order low-pass filtering algorithm are determined according to the actual debugging results, and the maximum amplitude and minimum amplitude of the calibrable parameters of the limiting filtering algorithm are determined according to the actual debugging results.

[0048] Step 14: Sum the pre-control target injection amount of step 12 and the PID target injection amount of step 13 to obtain the final injection amount.

[0049] Step 15: After performing first-order low-pass filtering and limiting filtering on the final injection amount in step 14, the filtering result is output to the next step. Among them, the time constant and other calibrable parameters of the first-order low-pass filtering algorithm are determined according to the actual debugging results, and the maximum amplitude and minimum amplitude of the calibrable parameters of the limiting filtering algorithm are determined according to the actual debugging results.

[0050] Step 16: Read the real-time operating data such as intake pressure and intake temperature in real time.

[0051] Step 17: To avoid excessive changes in fuel injection, poor combustion of the diesel engine, and black smoke from the diesel engine exhaust, the smoke limit fuel quantity is calibrated using real-time operating data such as the diesel engine intake pressure and intake temperature. The smoke limit fuel quantity determines that the amount of fuel that can be injected under the current operating conditions cannot exceed the smoke limit fuel quantity.

[0052] Step 18: Compare the final fuel injection amount outputted in step 15 with the smoke limit fuel amount outputted in step 17. If the final fuel injection amount is less than the smoke limit fuel amount, the final fuel injection amount is used as the final required fuel injection amount; otherwise, the smoke limit fuel amount is used as the final required fuel injection amount.

[0053] Step 19: The final required injection amount output from step 18 is transmitted to the injector driver module to inject the specified amount of oil.

[0054] Step 20: The module completes the calculation of the current cycle and waits for the next calculation cycle to start.

[0055] The algorithm requires the external load device to inform the required speed and torque in advance, so that the target injection amount can be accurately calculated to meet the stringent requirements of improving the transient response time of the diesel engine constant speed control and reducing the speed overshoot rate. The algorithm can be applied to the diesel engine constant speed mode, and has any scenario that interacts with the diesel engine to demand speed and torque, including generators, range extenders, etc.

[0056] The above is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the structure of the present invention, which will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. A method for controlling sudden load changes in a diesel engine constant speed control mode, characterized in that: Obtaining a required torque of an external device, and correcting the required torque by a required torque correction coefficient to obtain a final required torque; Read the current speed of the diesel engine, and calibrate the pre-control target injection amount of the diesel engine according to the final required torque and the current speed; The required speed of the external device is obtained, a PID target fuel injection amount is calculated according to the required speed and the current speed, and the pre-control target fuel injection amount and the PID target fuel injection amount are added to obtain a final fuel injection amount; the smoke limit fuel amount is obtained according to the real-time operating condition data of the diesel engine, and the final fuel injection amount is analyzed and judged according to the smoke limit fuel amount to determine the final required fuel injection amount.

2. A method for controlling sudden load changes in a diesel engine constant speed control mode according to claim 1, characterized in that: The method for determining the final required fuel injection amount is: The smoke-limited fuel amount is compared with the final fuel injection amount. If the final fuel injection amount is less than the smoke-limited fuel amount, the final fuel injection amount is used as the final required fuel injection amount; otherwise, the smoke-limited fuel amount is used as the final required fuel injection amount.

3. The method for controlling sudden load changes in a diesel engine constant speed control mode according to claim 1, characterized in that: The calculation method of the PID target injection amount is: The required speed and the current speed are subtracted to obtain a speed difference, and the speed difference is multiplied by a proportional coefficient of a P component to obtain a required fuel volume of the P component; The integral value of the speed difference is multiplied by the proportional coefficient of the I component to obtain the required oil quantity of the I component; Multiplying the differential value of the speed difference by the proportional coefficient of the D component to obtain the required oil quantity of the D component; The required fuel quantity of the I component is frozen, and the required fuel quantity of the P component, the frozen required fuel quantity of the I component, and the required fuel quantity of the D component are summed to obtain a PID target fuel injection quantity.

4. A method for controlling sudden load changes in a diesel engine constant speed control mode according to claim 3, characterized in that: The method of freezing the required oil quantity of the component I is as follows: When the required oil quantity of the I component is greater than the set I component oil quantity threshold, the required oil quantity of the I component at the previous moment is locked as the current required oil quantity of the I component; when the required oil quantity of the I component is less than the set I component oil quantity threshold, the required oil quantity of the I component at the next moment is locked as the current required oil quantity of the I component.

5. The method for controlling sudden load changes in a diesel engine constant speed control mode according to claim 1, characterized in that: The final required torque is the product of the required torque correction coefficient and the required torque.

6. A method for controlling sudden load changes in a diesel engine constant speed control mode according to claim 1 or 5, characterized in that: The method for obtaining the required torque correction coefficient is: A plurality of real-time performance data of the diesel engine is obtained, and a torque correction coefficient corresponding to the real-time performance data is searched through a preset performance data-torque correction coefficient curve according to the real-time performance data, and all the torque correction coefficients are summed to obtain a required torque correction coefficient.

7. The method for controlling sudden load changes in a diesel engine constant speed control mode according to claim 1, characterized in that: A first timing time is set; if the required torque of the external device cannot be obtained during the first timing time, a fault message is reported, and the current required torque is set to the last correctly received required torque.

8. The method for controlling sudden load changes in a diesel engine constant speed control mode according to claim 7, characterized in that: If the required rotation speed of the external device cannot be obtained within the first timing period, a fault message is reported, and the current required rotation speed is set to the last correctly received required rotation speed.

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