A dual-fuel engine control method and system

Abstract

A dual-fuel engine control method and system includes the following steps: Step 1) Determine if the vehicle is under high load; if so, proceed to Step 2); Step 2) Obtain the slope value θ0 of the vehicle's current position and predict the slope value θ1 of the position point ahead of the vehicle, and determine if θ1 < 0 < θ0 is satisfied; if so, calculate the increment of the driving force of the vehicle at the current position and the position point ahead; Step 3) Search in the calibration data according to the change in output torque to obtain the substitution rate A corresponding to the current torque decreasing by the change in output torque; Step 4) Obtain the distance between the vehicle and the position point ahead with a slope value of θ1 in real time, and determine if the vehicle will approach the position point ahead; if so, proceed to Step 5); Step 5) Increase the substitution rate of the vehicle-controlled engine to A, and continuously determine if the vehicle has reached the position point ahead; if so, restore the substitution rate of the vehicle-controlled engine to the default value of the current state, and return to Step 1).

Description

Technical Field

[0001] This invention relates to the field of dual-fuel engine control, and in particular to a dual-fuel engine control method and system. Background Technology

[0002] A dual-fuel engine is a diesel engine equipped with a natural gas supply system, using diesel as the ignition fuel and natural gas as the primary fuel for power output. These engines offer good fuel economy, flexible fuel selection, high thermal efficiency, and good emissions performance, especially with lower emissions of nitrogen oxides and particulate matter. Compared to single-fuel engines, they have certain advantages, making the development of dual-fuel engines a significant economic and environmental endeavor.

[0003] Currently, many dual-fuel products are modified from existing engines, typically requiring the addition of an alternative fuel supply system and an electronic control system to control the injection of both the original and alternative fuels. The substitution rate of a dual-fuel engine refers to the ratio of the amount of diesel fuel replaced by natural gas to the amount of diesel fuel consumed in pure diesel mode, at the same engine power output. Specifically: (Diesel consumption in pure diesel mode - Diesel consumption in dual-fuel mode) / Diesel consumption in pure diesel mode.

[0004] Typically, the power performance of a converted dual-fuel engine should be consistent with that of the original pure diesel engine. However, in existing dual-fuel engine control systems, under high load conditions, natural gas cannot provide sufficient power. Therefore, the substitution rate generally needs to be reduced under high load to maintain vehicle power, thus sacrificing some fuel economy. Furthermore, during vehicle operation, the control system does not consider road gradient information when controlling the engine substitution rate, causing the engine output torque to fluctuate with the substitution rate, potentially affecting the driver's driving experience. Summary of the Invention

[0005] The main objective of this invention is to overcome the shortcomings of existing technologies where the substitution rate of dual-fuel engines needs to be reduced when vehicles are under high load, resulting in a loss of fuel economy. This invention proposes a dual-fuel engine control method and system.

[0006] The present invention adopts the following technical solution:

[0007] A dual-fuel engine control method is characterized by pre-calibrating the change in output torque of the dual-fuel engine after increasing the default substitution rate by a preset step size, thus forming calibration data. Specifically, the method pre-calibrates the change in engine output torque of the dual-fuel engine after increasing the default substitution rate by a preset step size at a fixed throttle pedal opening and engine speed, repeating this step to iterate through all throttle pedal opening values ​​and engine speeds to complete the calibration.

[0008] The specific control methods are as follows:

[0009] Step 1) Determine if the vehicle is under high load. If yes, proceed to Step 2). Otherwise, repeat this step.

[0010] In this step, the vehicle has pre-stored the engine control parameters, including the engine load rate and the corresponding replacement rate. In step 1), the vehicle obtains the current engine load rate P% and the corresponding replacement rate T1, and queries the control parameters to find the replacement rate T2 corresponding to the current engine load rate reduction. It then determines whether the current replacement rate T1% is less than the replacement rate T2. If so, the vehicle is in a high load state.

[0011] In this step, it is also possible to determine whether the vehicle is under high load by obtaining the vehicle's current total mass.

[0012] Step 2) Obtain the slope value θ0 of the vehicle's current position and predict the slope value θ1 of the position point in front of the vehicle. Determine whether θ1 < 0 < θ0 is satisfied. If so, calculate the increment of the driving force of the vehicle at the current position and the position point in front.

[0013] In this step, the slope value of the vehicle's current position and the slope value of the position point ahead of the vehicle can be obtained through an electronic horizon system. The electronic horizon system outputs geographical information of the equally spaced positions on the road ahead of the vehicle. The current terrain slope value is obtained by interpolation between the slope values ​​of the previous and next positions of the vehicle's current position. The formula for calculating the increment of the driving force is mgsin(θ0-θ1), where m is the mass of the vehicle and g is the acceleration due to gravity.

[0014] Step 3) Calculate the corresponding change in output torque based on the increment of the driving force, and search the calibration data to obtain the substitution rate A corresponding to the decrease in output torque by the current torque. The formula for calculating the change in output torque is as follows: r is the radius of the wheel, i g i is the gearbox transmission ratio, and i0 is the vehicle's final drive transmission ratio.

[0015] Step 4) Real-time acquisition of the distance between the vehicle and the forward position point with a slope value of θ1, and determination of whether the vehicle will approach the forward position point. If yes, proceed to step 5); otherwise, repeat the step. In step 4), determining whether the vehicle will approach the forward position point specifically involves: continuously acquiring the distance D between the vehicle and the forward position point, and determining whether the time required for the vehicle to reach the forward position point at the current speed is less than a preset threshold. If yes, it is determined that the vehicle is approaching the forward position point.

[0016] Step 5) Increase the vehicle control engine's substitution rate to A, and continuously determine whether the vehicle has reached the forward position point. If so, restore the vehicle control engine's substitution rate to the default value of the current state and return to Step 1).

[0017] A dual-fuel engine control system, characterized in that it comprises the following:

[0018] The data acquisition module is used to collect relevant information about the vehicle, including at least calibration data, control parameters, the slope value θ0 of the vehicle's current position, and the slope value θ1 of the position point in front of the vehicle.

[0019] The load status determination module is used to determine whether the vehicle is under high load.

[0020] The calculation module calculates the increment of driving force and the corresponding change in output torque at the current position and the forward position point when the vehicle is under high load, satisfying θ1<0<θ0. It then searches calibration data to obtain the substitution rate A corresponding to the current torque decreasing by the change in output torque.

[0021] The control module controls the engine's substitution rate to increase by value A when the vehicle approaches the forward position point, and restores the substitution rate to the default value of the current state when the vehicle reaches the forward position point.

[0022] As can be seen from the above description of the present invention, compared with the prior art, the present invention has the following beneficial effects:

[0023] In this invention, when the vehicle is under high load, the replacement rate of the current dual-fuel engine is actively increased by predicting the terrain ahead. The loss of power due to the increased replacement rate is compensated by the terrain, which can improve the energy economy of the whole vehicle and improve emissions to a certain extent.

[0024] In this invention, whether a vehicle is under high load can be determined by the engine load rate and the corresponding replacement rate, or by obtaining the current total mass of the vehicle.

[0025] In this invention, the current slope value of the vehicle and the predicted slope value of the position point ahead of the vehicle are obtained through an electronic horizon system. The current terrain slope value of the vehicle is obtained by interpolation between the slope value of the previous position point and the slope value of the next position point of the vehicle, thereby predicting the slope ahead in real time. Attached Figure Description

[0026] Figure 1 This is a flowchart of the method of the present invention;

[0027] Figure 2 Geographic information output for Electronic Horizon.

[0028] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Detailed Implementation

[0029] The present invention will be further described below through specific embodiments.

[0030] In this invention, the terms "first," "second," and "third," etc., are used only to distinguish similar objects and are not necessarily used to describe a specific order or sequence, nor should they be construed as indicating or implying relative importance. The use of terms such as "upper," "lower," "left," "right," "front," and "rear" to indicate orientation or positional relationships is based on the orientation or positional relationships shown in the accompanying drawings and is only for the convenience of describing the invention, not to indicate or imply that the device referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on the scope of protection of this invention. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0031] Furthermore, in the description of this application, unless otherwise stated, "multiple" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0032] Example 1

[0033] See Figure 1 A dual-fuel engine control method involves pre-calibrating the change in output torque of the dual-fuel engine after increasing the default substitution rate by a preset step size, thus forming calibration data. The substitution rate of the dual-fuel engine refers to the ratio of the amount of diesel fuel replaced by natural gas to the amount of diesel fuel consumed in pure diesel operation mode, when the engine has the same power output.

[0034] Specifically, the dual-fuel engine is pre-calibrated at a fixed throttle pedal opening and engine speed. The change in engine output torque corresponding to an increase in the default substitution rate by a preset step size is then calculated. This process is repeated, iterating through all throttle pedal opening values ​​and engine speeds to complete the calibration. The step size represents the change in substitution rate, which can be a small value and is not limited here. In other words, based on the original calibration data, the changes in substitution rate and output torque are added. For example, for already calibrated throttle pedal opening, engine speed, substitution rate, and output torque, the changes in substitution rate and output torque are added.

[0035] The specific control method of the present invention is as follows:

[0036] Step 1) Determine if the vehicle is under high load. If yes, proceed to step 2); otherwise, repeat this step. In this embodiment, the high load condition of the vehicle can be determined by the engine load rate and the corresponding substitution rate.

[0037] Specifically, the vehicle can pre-store engine control parameters, including engine load rate and corresponding replacement rate. In this step, the vehicle can obtain the current engine load rate P% and the corresponding replacement rate T1, and query the control parameters for the replacement rate T2 corresponding to reducing the current engine load rate (e.g., (P-1)%). It then determines whether the current replacement rate T1% is less than the replacement rate T2. If so, it means that increasing the engine output load from (P-1)% to P% cannot be achieved simply by increasing the fuel quantity while maintaining the replacement rate. The engine has entered a state where increasing the output load requires continuously reducing the replacement rate, i.e., entering a high-load state for a dual-fuel engine. The amount of load rate reduction, i.e., the change in load rate, can be set according to requirements and is not limited here.

[0038] Step 2) Obtain the slope value θ0 of the vehicle's current position and predict the slope value θ1 of the position point in front of the vehicle. Determine whether θ1 < 0 < θ0 is satisfied. If so, calculate the increment of the driving force of the vehicle at the current position and the position point in front.

[0039] In this invention, the slope value of the vehicle's current position and the slope value of the position point ahead of the vehicle can be obtained through an Electronic Horizon System (E-Horizon). The E-Horizon System outputs the geographical information of the position points of the road ahead of the vehicle that are evenly distributed. The current terrain slope value of the vehicle is obtained by interpolation between the slope value of the previous position point and the slope value of the next position point.

[0040] The Electronic Horizon System (EHS) transmits geographic information outwards as a series of points ahead of the road, along with their attributes. This information is presented as geographic element data combined with road offsets. The EHS can then transmit this information to the relevant dual-fuel engine controller system via the in-vehicle CAN bus or Ethernet bus using the standard ADAS IS protocol.

[0041] The Electronic Horizon System (EHS) transmits geographic information outwards as a series of points ahead of the road and their attributes. This information is presented as geographic element data combined with road offsets. For example, see... Figure 2The system displays the vehicle's current position P and three consecutive position points P1, P2, and P3, representing the continuous road slope data output by the electronic horizon system. Road points P1, P2, and P3 are represented in the electronic horizon system as their offset from the road's starting point and their corresponding slope value θ. The road slope data broadcast by the electronic horizon system is a series of consecutive short, equally spaced points at intervals of K meters (e.g., 10 meters). The vehicle position P is also converted by the electronic horizon system into its offset from the road's starting point. For example, in this case, the offset of vehicle position P is 15. According to the electronic horizon information, the distance from the vehicle's current position to the next position point P1 is D = 20 - 15 = 5 meters. The offset of vehicle position P is continuously updated as the vehicle moves. By calculating the offset difference, the real-time distance D between the vehicle's current position P and the preceding position point P1, as described above, is continuously obtained from the electronic horizon. Based on the vehicle's real-time speed, the time to reach position point P1 is calculated. Similarly, as the vehicle passes point P1 and begins to approach point P2, the real-time distance D between the vehicle's current position and the preceding point P2 is continuously obtained, and the time to reach point P2 is calculated based on the vehicle's real-time speed. The slope value of the vehicle's current position can be obtained by interpolation between the slope values ​​of the previous and next points.

[0042] In this invention, the formula for calculating the incremental driving force is mgsin((θ0-θ1), where m is the mass of the vehicle and g is the acceleration due to gravity.

[0043] Step 3) Calculate the corresponding change in output torque based on the increment of driving force, search in the calibration data, and obtain the substitution rate A corresponding to the current torque reducing the change in output torque.

[0044] The formula for calculating the change in output torque is as follows: r is the radius of the wheel, i g i is the gearbox transmission ratio, and i0 is the vehicle's final drive transmission ratio.

[0045] Step 4) Obtain the distance between the vehicle and the forward position point with a slope value of θ1 in real time, and determine whether the vehicle will approach the forward position point. If yes, proceed to step 5); otherwise, repeat this step.

[0046] The determination of whether a vehicle is approaching a given location point involves: continuously acquiring the distance D between the vehicle and the given location point; determining whether the time required for the vehicle to reach the location point at its current speed is less than a preset threshold; if so, the vehicle is considered to be approaching the location point. This preset threshold can be set as needed; for example, if it is 1 second, then D / V < 1, where V is the vehicle's current speed.

[0047] Step 5) Increase the vehicle control engine's substitution rate to A, and continuously determine whether the vehicle has reached the forward position point. If so, restore the vehicle control engine's substitution rate to the default value of the current state, and return to Step 1) to cycle through terrain prediction and optimization control.

[0048] In this step, when the vehicle reaches the forward position point with a slope value of θ1, the engine's substitution rate is increased to A. This improves the vehicle's economy and emissions, but the torque output is slightly reduced.

[0049] The present invention also proposes a dual-fuel engine control system, comprising the following:

[0050] The data acquisition module is used to collect relevant vehicle information, including at least calibration data, control parameters, the slope value θ0 of the vehicle's current position, and the slope value θ1 of the point ahead of the vehicle. This acquisition module is used to collect the relevant vehicle information required by the aforementioned dual-fuel engine control method.

[0051] The load status determination module is used to determine whether the vehicle is under high load. It can use the engine load rate and corresponding replacement rate, as described above, to determine whether the vehicle is under high load.

[0052] The calculation module calculates the increment of driving force and the corresponding change in output torque at the current position and the forward position point when the vehicle is under high load, satisfying θ1<0<θ0. It then searches calibration data to obtain the substitution rate A corresponding to the current torque decreasing by the change in output torque.

[0053] The control module controls the engine's substitution rate to increase by value A when the vehicle approaches the forward position point, and restores the substitution rate to the default value of the current state when the vehicle reaches the forward position point.

[0054] The working principle of the system of this invention is as follows:

[0055] Step 1) The load status judgment module determines whether the vehicle is under high load. If yes, proceed to step 2); otherwise, repeat this step.

[0056] Step 2) The acquisition module obtains the slope value θ0 of the vehicle's current position and predicts the slope value θ1 of the position point in front of the vehicle. The calculation module determines whether θ1<0<θ0 is satisfied. If so, it calculates the increment of the driving force of the vehicle at the current position and the position point in front.

[0057] Step 3) The calculation module calculates the corresponding change in output torque based on the increment of the driving force, searches in the calibration data, and obtains the substitution rate A corresponding to the current torque reducing the change in output torque.

[0058] Step 4) The acquisition module obtains the distance between the vehicle and the forward position point with a slope value of θ1 in real time, and determines whether the vehicle will approach the forward position point. If yes, proceed to step 5); otherwise, repeat this step.

[0059] Step 5) The control module increases the engine's replacement rate to A and continuously checks whether the vehicle has reached the forward position point. If so, the vehicle controls the engine's replacement rate to the default value of the current state and returns to Step 1).

[0060] The method and system of the present invention can improve the substitution rate and improve economy in the instant of terrain change. The power lost due to economic reasons will be quickly made up by the slope ahead, so it will not affect the driver's driving experience and is easy to use.

[0061] Example 2

[0062] The present invention also proposes a dual-fuel engine control method and system, the main structure of which is the same as that of Embodiment 1, the difference being that: in step 1), the current total mass of the vehicle is obtained by known methods such as load sensors or dynamic calculations to determine whether the vehicle is in a high-load state.

[0063] The above are merely specific embodiments of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial modifications made to the present invention using this concept shall be considered as infringing upon the protection scope of the present invention.

Claims

1. A dual-fuel engine control method, characterized by, The calibration data is generated by pre-calibrating the change in output torque of the dual-fuel engine after increasing the default substitution rate by a preset step size; the specific control method is as follows. Step 1) Determine if the vehicle is under high load. If yes, proceed to Step 2). Otherwise, repeat this step. Step 2) Obtain the slope value of the vehicle's current position. And predict the slope value of the point in front of the vehicle. Determine whether the condition is met. < 0 < If so, calculate the increment of the vehicle's driving force at the current position and the position ahead; Step 3) Calculate the corresponding change in output torque based on the increment of driving force, search in the calibration data to obtain the substitution rate A corresponding to the current torque reducing the change in output torque; Step 4) Obtain vehicle and slope values ​​in real time The distance to the forward position point is calculated, and it is determined whether the vehicle will approach the forward position point. If so, proceed to step 5; otherwise, repeat the step. Step 5) Increase the vehicle control engine's substitution rate to A, and continuously determine whether the vehicle has reached the forward position point. If so, restore the vehicle control engine's substitution rate to the default value of the current state and return to Step 1.

2. The dual-fuel engine control method as described in claim 1, characterized in that, The dual-fuel engine is pre-calibrated at a fixed throttle pedal opening and engine speed. The change in engine output torque corresponding to the increase of the default substitution rate by a preset step size is determined. This step is repeated to traverse all throttle pedal opening values ​​and engine speeds to complete the calibration.

3. The dual-fuel engine control method as described in claim 1, characterized in that, In step 1), the current total mass of the vehicle is obtained to determine whether the vehicle is under high load.

4. The dual-fuel engine control method as described in claim 1, characterized in that, The vehicle has pre-stored engine control parameters, including engine load rate and corresponding replacement rate. In step 1), the vehicle obtains the current engine load rate P% and the corresponding replacement rate T1, and queries the control parameters to find the replacement rate T2 corresponding to the current engine load rate reduction. It then determines whether the current replacement rate T1% is less than the replacement rate T2. If so, the vehicle is in a high load state.

5. The dual-fuel engine control method as described in claim 1, characterized in that, In step 2), the slope value of the vehicle's current position and the slope value of the position point in front of the vehicle are obtained through the electronic horizon system.

6. The dual-fuel engine control method as described in claim 5, characterized in that, The electronic horizon system outputs geographic information of the locations of the road ahead of the vehicle, which are evenly distributed. The current terrain slope value of the vehicle is obtained by interpolation between the slope value of the previous location and the slope value of the next location.

7. The dual-fuel engine control method as described in claim 1, characterized in that, In step 2), the formula for calculating the increment of the driving force is as follows: ,in For the quality of the vehicle, This is the acceleration due to gravity.

8. The dual-fuel engine control method as described in claim 7, characterized in that, In step 3), the formula for calculating the change in output torque is as follows: , For the wheel radius, For the gearbox transmission ratio, This refers to the transmission ratio of the vehicle's main reducer.

9. The dual-fuel engine control method as described in claim 1, characterized in that, In step 4), determining whether the vehicle is approaching the forward position point specifically involves: continuously obtaining the distance D between the vehicle and the forward position point, and determining whether the time required for the vehicle to reach the forward position point at the current speed is less than a preset threshold. If so, it is determined that the vehicle is approaching the forward position point.

10. A dual-fuel engine control system, characterized in that, Including the following: The data acquisition module is used to collect relevant vehicle information, including at least calibration data, control parameters, and the slope value of the vehicle's current position. , slope value of the point in front of the vehicle The calibration data includes the change in output torque corresponding to the pre-calibrated dual-fuel engine after increasing the default substitution rate by a preset step size; the control parameters include engine load rate and the corresponding substitution rate. The load status determination module is used to determine whether the vehicle is under high load. The calculation module calculates the vehicle's performance when it is under high load, ensuring it meets the required standards. < 0 < The current position and the increment of driving force at the forward position point, as well as the corresponding change in output torque, are used to search calibration data to obtain the substitution rate A corresponding to the current torque decreasing by this change in output torque; The control module increases the engine's substitution rate to A when the vehicle approaches the forward position point, and restores the substitution rate to the default value of the current state when the vehicle reaches the forward position point.

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