Method for regulating and controlling rotating speed of turbocharger
阅读说明：本技术 涡轮增压器转速调控方法 (Method for regulating and controlling rotating speed of turbocharger ) 是由 马勇 赵真真 王右 于 2021-07-12 设计创作，主要内容包括：本发明公开了一种涡轮增压器转速调控方法,主要设计构思是可以通过在涡轮增压器的涡壳入口及出口布置的压力温度传感器,监测发动机排气输出能量,即用于推动涡轮增压器做功的能量,再结合预先基于不同排气能量下标定的涡轮增压器转速关系,预估当前排气输出能量下的涡轮增压器转速,进而与预设的转速限制进行比对实现对增压器转速的调控,本发明的核心构思是由排气情况正向判断涡轮增压器之后的工作状态,相对现有技术反其道而行,有效规避通过增压后的效果逆向推测涡轮增压器转速的弊端,大幅降低了增压器超速误判断概率,因而能够在避免涡轮增压器超速现象发生的同时,保证涡轮增压器的高效运行。(The invention discloses a method for regulating and controlling the rotating speed of a turbocharger, which has the main design concept that the exhaust output energy of an engine, namely the energy for pushing the turbocharger to do work, can be monitored through pressure and temperature sensors arranged at the inlet and the outlet of a volute of the turbocharger, the rotating speed of the turbocharger under the current exhaust output energy is estimated by combining the energy for pushing the turbocharger to do work and the rotating speed relationship of the turbocharger calibrated on the basis of different exhaust energy in advance, and then the rotating speed of the turbocharger is compared with the preset rotating speed limit to regulate and control the rotating speed of the turbocharger, the core concept of the invention is that the working state of the turbocharger is judged positively according to the exhaust condition, the method is carried out in a reverse way compared with the prior art, the defect that the rotating speed of the turbocharger is reversely presumed by the effect after supercharging is effectively avoided, the overspeed misjudgment probability of the turbocharger is greatly reduced, and the overspeed phenomenon of the turbocharger can be avoided, ensuring efficient operation of the turbocharger.)
1. A method of regulating turbocharger rotational speed, comprising:
acquiring pre-turbine pressure and temperature data in real time through a pressure and temperature sensor arranged at the inlet of a turbine of a turbocharger;
calculating the current exhaust energy of the engine according to the preswirl pressure and temperature data;
determining the current rotating speed of the turbocharger corresponding to the engine exhaust energy according to the engine exhaust energy and the relationship between the exhaust energy calibrated in advance and the rotating speed of the turbocharger;
comparing the relation between the current rotating speed and the rotating speed limit value of the turbocharger, and judging whether the relation accords with a preset rotating speed margin value;
and if not, driving a waste gas bypass valve of the turbocharger to increase the opening degree so as to regulate and control the current rotating speed of the turbocharger.
2. The method for regulating the rotating speed of the turbocharger as claimed in claim 1, wherein the calibration mode of the relation between the exhaust energy and the rotating speed of the turbocharger comprises the following steps:
acquiring post-vortex pressure data by a pressure sensor arranged at a turbine outlet of a turbocharger;
in the calibration stage of the engine rack, corresponding exhaust energy is obtained according to different preswirl pressure and temperature data;
according to different exhaust energy, corresponding pre-vortex pressure and temperature data and post-vortex pressure data, a turbine operation curve of the turbocharger is calculated in a simulation mode, and the turbine operation curve is used for representing the relation between the pre-vortex pressure and temperature data and the turbocharger.
3. The method of claim 2, wherein the simulating the turbine operating curve of the turbocharger comprises:
a three-dimensional mapping curve is simulated through a turbocharger single body bench test, the X axis of the three-dimensional mapping curve represents the expansion ratio of the turbocharger obtained by the ratio of the pressure data before the vortex to the pressure data after the vortex, the Y axis represents the reduced exhaust flow corresponding to the exhaust energy, and the Z axis is the rotating speed of the turbocharger.
4. The method of claim 3, wherein the reduced exhaust flow is calculated by:
calculating the actual exhaust flow by combining the preswirl pressure and temperature data, a thermodynamic formula and the set displacement of the engine;
the reduced exhaust flow rate Mc is calculated as follows:
Mc＝M*T31/2/P3*100
where M is the actual exhaust flow, T3 is pre-vortex temperature data, and P3 is pre-vortex pressure data.
5. The method for regulating the rotation speed of the turbocharger according to any one of claims 1 to 4, further comprising: and if the comparison result of the current rotating speed and the rotating speed limit value of the turbocharger accords with a preset rotating speed allowance value, keeping the current opening degree of the waste gas bypass valve.
Technical Field
The invention relates to the field of engine control, in particular to a method for regulating and controlling the rotating speed of a turbocharger.
Background
With the stricter national fuel consumption regulations, the engine supercharging technology becomes the development direction of various automobile manufacturers. Turbocharging is that exhaust energy after combustion of the engine is utilized to do work to push the turbine to rotate at a high speed so as to compress fresh air, so that the air inflow is increased, and the dynamic property of the engine is improved. The turbocharger is a high-speed rotating part (the highest rotating speed of an impeller can reach 25 thousands of revolutions), works under the working condition of sharp change of the working condition, and can generate an overspeed phenomenon (the rotating speed of the turbocharger exceeds the maximum rotating speed requirement of a zero-crossing part material) during working, so that the turbocharger fails. Therefore, it is common to provide relevant components and sensors on or in the intake air line of the turbocharger, and protect the turbocharger from overspeed by means of a corresponding control strategy.
The turbocharger with the waste gas bypass valve has the advantages that the opening degree of the waste gas bypass valve is gradually increased along with the increase of the rotating speed and the load of an engine, exhaust waste gas is enabled to bypass through the waste gas bypass valve, the exhaust waste gas is reduced to push a turbine to do work, and the overspeed of the turbocharger is avoided. The specific control strategy is as follows:
in order to ensure that the engine has set performance targets (engine torque) under different rotating speeds and different loads, the target intake pressure in an engine intake manifold needs to be controlled, and the turbocharger does not overspeed under different target pressures, when the engine is subjected to bench calibration, the target intake pressure required in the engine intake manifold is calibrated according to the performance targets and the rotation speed limit of the turbocharger, meanwhile, the actual rotating speed of the turbocharger under different supercharging pressures is measured in the bench calibration so as to ensure that the rotating speed of the turbocharger does not exceed the limit value, and the supercharging pressure limit values of different atmospheric temperature pressures are stored in an on-board Electronic Control Unit (ECU). And when the turbocharger is in an actual driving working condition, according to the target pressure under the corresponding working condition, the opening degree of the waste gas bypass valve is adjusted to control the air inlet pressure of the air inlet manifold, so that the actual air inlet pressure approaches to the target air inlet pressure, and meanwhile, the rotating speed of the turbocharger is estimated through boundary condition models such as the supercharging pressure temperature, the atmospheric pressure temperature and the like stored in the ECU, so that the rotating speed limit value is not exceeded. Therefore, the prior art judges whether the turbocharger has the overspeed risk or not based on the comparison of relevant boundary parameters such as pressure and temperature tested by relevant sensors and relevant estimation models stored in the ECU. The specific sensor arrangement and control logic is as follows:
referring to fig. 1, pressure and temperature at corresponding positions are tested by sensors S0, S1 and S2 (P, T), and then compared with an estimated model established by calibration of a rack in an ECU, a possible rotation speed TS of the turbocharger under the working condition is estimated, and if the estimated rotation speed TS of the turbocharger is smaller than a rotation speed limit value of the turbocharger and has a certain margin, the working condition is kept unchanged; if the estimated rotation speed TS is in danger of exceeding the rotation speed limit value, the ECU sends an instruction to the turbocharger to adjust the opening of the waste gas bypass valve, so that the rotation speed of the turbocharger is reduced to be within the rotation speed limit value of the turbocharger.
By adopting the prior scheme, the rotating speed of the turbocharger under the full working condition of the engine (different turbocharger supercharging pressure temperatures and different engine boundaries) needs to be tested in the calibration of the rack, and then a turbocharger rotating speed estimation model under the full working condition is established in the ECU; meanwhile, because the turbocharger is easy to overspeed under the highland condition, plateau calibration is required to confirm that the turbocharger does not overspeed under any working condition.
According to the scheme, the actual driving condition of the vehicle is complex, the actual rotating speed of the turbocharger is different from the estimated rotating speed easily due to the change of boundary conditions, the turbocharger still has overspeed risk, the turbocharger utilizes the exhaust energy after the combustion of the engine to do work to push the turbine to rotate at high speed so as to compress fresh air, the exhaust of the engine is a direct energy source for the operation of the turbocharger, the boost pressure is an expression result of the operation of the turbocharger, and the potential expression form of the turbocharger is also uncertain through the result reverse estimation.
In summary, the scheme is adopted to estimate the turbocharger rotating speed to have larger uncertainty and deviation, namely, the estimated model and the actual turbocharger rotating speed have difference, which also brings overspeed risk.
Disclosure of Invention
In view of the above, the present invention aims to provide a method for regulating the rotational speed of a turbocharger, so as to overcome the shortcomings of the prior art.
The technical scheme adopted by the invention is as follows:
a turbocharger speed regulation method, comprising:
acquiring pre-turbine pressure and temperature data in real time through a pressure and temperature sensor arranged at the inlet of a turbine of a turbocharger;
calculating the current exhaust energy of the engine according to the preswirl pressure and temperature data;
determining the current rotating speed of the turbocharger corresponding to the engine exhaust energy according to the engine exhaust energy and the relationship between the exhaust energy calibrated in advance and the rotating speed of the turbocharger;
comparing the relation between the current rotating speed and the rotating speed limit value of the turbocharger, and judging whether the relation accords with a preset rotating speed margin value;
and if not, driving a waste gas bypass valve of the turbocharger to increase the opening degree so as to regulate and control the current rotating speed of the turbocharger.
In at least one possible implementation manner, the calibration manner of the relation between the exhaust energy and the turbocharger speed comprises the following steps:
acquiring post-vortex pressure data by a pressure sensor arranged at a turbine outlet of a turbocharger;
in the calibration stage of the engine rack, corresponding exhaust energy is obtained according to different preswirl pressure and temperature data;
according to different exhaust energy, corresponding pre-vortex pressure and temperature data and post-vortex pressure data, a turbine operation curve of the turbocharger is calculated in a simulation mode, and the turbine operation curve is used for representing the relation between the pre-vortex pressure and temperature data and the turbocharger.
In at least one possible implementation, the simulation calculating a turbine operating curve of a turbocharger includes:
a three-dimensional mapping curve is simulated through a turbocharger single body bench test, the X axis of the three-dimensional mapping curve represents the expansion ratio of the turbocharger obtained by the ratio of the pressure data before the vortex to the pressure data after the vortex, the Y axis represents the reduced exhaust flow corresponding to the exhaust energy, and the Z axis is the rotating speed of the turbocharger.
In at least one possible implementation manner, the calculating manner of the reduced exhaust flow includes:
calculating the actual exhaust flow by combining the preswirl pressure and temperature data, a thermodynamic formula and the set displacement of the engine;
the reduced exhaust flow rate Mc is calculated as follows:
Mc＝M*T31/2/P3*100
where M is the actual exhaust flow, T3 is pre-vortex temperature data, and P3 is pre-vortex pressure data.
In at least one possible implementation manner, the regulation and control method further includes: and if the comparison result of the current rotating speed and the rotating speed limit value of the turbocharger accords with a preset rotating speed allowance value, keeping the current opening degree of the waste gas bypass valve.
The design concept of the invention is that the exhaust output energy of an engine, namely the energy for pushing the turbocharger to do work, can be monitored through pressure and temperature sensors arranged at the inlet and the outlet of a volute of the turbocharger, the rotating speed of the turbocharger under the current exhaust output energy is estimated by combining the rotating speed relationship of the turbocharger calibrated based on different exhaust energies in advance, and then the rotating speed of the turbocharger is compared with the preset rotating speed limit to realize the regulation and control of the rotating speed of the turbocharger, the core concept of the invention is that the working state behind the turbocharger is judged in the positive direction of the exhaust condition, the operation is carried out in the opposite direction of the prior art, the defect that the rotating speed of the turbocharger is reversely estimated through the effect after pressurization (by the pressure and temperature sensors in pipelines before and after pressurization and a preset model) is effectively avoided, the overspeed misjudgment probability of the turbocharger is greatly reduced, and the overspeed phenomenon of the turbocharger can be avoided, ensuring efficient operation of the turbocharger.
Drawings
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described with reference to the accompanying drawings, in which:
fig. 1 is a schematic diagram of a conventional turbocharger rotational speed control architecture;
fig. 2 is a flowchart of a turbocharger rotational speed control method according to an embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative only and should not be construed as limiting the invention.
The invention provides an embodiment of a method for regulating and controlling the rotating speed of a turbocharger, and specifically, as shown in fig. 1, the method can comprise the following steps:
step S1, acquiring preswirl pressure and temperature data in real time through a pressure and temperature sensor arranged at the inlet of a turbine of the turbocharger;
step S2, calculating the current exhaust energy of the engine according to the pre-vortex pressure and temperature data;
step S3, determining the current rotating speed of the turbocharger corresponding to the engine exhaust energy according to the engine exhaust energy and the relationship between the exhaust energy calibrated in advance and the rotating speed of the turbocharger;
step S4, comparing the relation between the current rotating speed and the rotating speed limit value of the turbocharger, and judging whether the preset rotating speed tolerance value is met;
if not, step S5 is executed to drive the waste gate valve of the turbocharger to increase the opening degree to regulate the current rotation speed of the turbocharger.
Specifically, the exhaust energy and turbocharger speed relationship may be calibrated as follows: the method comprises the steps of acquiring post-turbine pressure data through a pressure sensor arranged at the outlet of a turbine of a turbocharger, solving corresponding exhaust energy according to different pre-turbine pressure and temperature data in an engine bench calibration stage, namely obtaining the temperature and pressure of exhaust (the inlet of the turbine of the turbocharger) under the full working condition of an engine, and calculating the exhaust energy according to the pre-turbine pressure and temperature data. And then, according to different exhaust energy, corresponding pre-vortex pressure and temperature data and post-vortex pressure data, a turbine operation curve of the turbocharger is calculated in a simulation mode, and the turbine operation curve is used for representing the relation between the pre-vortex pressure and temperature data and the turbocharger.
The simulation described herein calculates the turbine operating curve of a turbocharger preferably in the following manner: a three-dimensional mapping curve is simulated through a turbocharger single body bench test, the X axis of the three-dimensional mapping curve represents the expansion ratio of the turbocharger obtained by the ratio of the pressure data before the vortex to the pressure data after the vortex, the Y axis represents the reduced exhaust flow corresponding to the exhaust energy, and the Z axis is the rotating speed of the turbocharger. That is, the abscissa of the graph represents the expansion ratio of the turbocharger, i.e., the ratio of the pressure before the turbine of the turbocharger to the pressure after the turbine, and the ordinate represents the reduced exhaust flow rate under the pressure-temperature condition of the turbine, and the turbocharger has a fixed rotation speed under the exhaust energy, so that the rotation speed of the turbocharger can be estimated in real time through the above.
In practical operation, the calculation of the reduced exhaust flow rate may be performed by combining the pre-turbine pressure and temperature data, the thermodynamic equation, and the engine displacement to calculate the actual exhaust flow rate (the thermodynamic equation PV is MRT, and the actual exhaust flow rate M is P3V/(RT3), where R is the thermodynamic constant 8.314 and V is the engine displacement); then, the reduced exhaust flow rate Mc is calculated as follows:
Mc＝M*T31/2/P3*100
where M is the actual exhaust flow, T3 is pre-vortex temperature data, and P3 is pre-vortex pressure data.
According to the method, when the estimated rotation speed of the turbocharger is less than or equal to (1-3%) n (n is a preset rotation speed limit value of the turbocharger, and 3% is a margin value), the opening of a waste gas bypass valve of the turbocharger can be kept unchanged through the ECU, namely the corresponding turbine front pressure temperature and the corresponding reduced exhaust flow of the turbocharger are unchanged; when the estimated rotation speed of the turbocharger exceeds the rotation speed limit value n of the turbocharger, the ECU can drive a waste gas bypass valve of the turbocharger to increase the opening degree, so that the estimated rotation speed of the turbocharger meets n less than or equal to (1-3%).
In summary, the design concept of the present invention is that the pressure and temperature sensors disposed at the inlet and outlet of the volute of the turbocharger monitor the exhaust output energy of the engine, that is, the energy for pushing the turbocharger to do work, and then, in combination with the relationship of the turbocharger rotational speed calibrated in advance based on different exhaust energies, the rotational speed of the turbocharger under the current exhaust output energy is estimated, and then compared with the preset rotational speed limit to realize the regulation and control of the rotational speed of the turbocharger, the core concept of the present invention is to determine the working state of the turbocharger in the forward direction by the exhaust condition, and to reverse the operation of the turbocharger compared with the prior art, effectively avoid the disadvantage of reversely estimating the rotational speed of the turbocharger by the effect after supercharging (by the pressure and temperature sensors in the pipeline before and after supercharging and the preset model), greatly reduce the overspeed misjudgment probability of the turbocharger, so that the overspeed phenomenon of the turbocharger can be avoided, ensuring efficient operation of the turbocharger.
In the embodiments of the present invention, "at least one" means one or more, "a plurality" means two or more. "and/or" describes the association relationship of the associated objects, and means that there may be three relationships, for example, a and/or B, and may mean that a exists alone, a and B exist simultaneously, and B exists alone. Wherein A and B can be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship. "at least one of the following" and similar expressions refer to any combination of these items, including any combination of singular or plural items. For example, at least one of a, b, and c may represent: a, b, c, a and b, a and c, b and c or a and b and c, wherein a, b and c can be single or multiple.
The structure, features and effects of the present invention have been described in detail with reference to the embodiments shown in the drawings, but the above embodiments are merely preferred embodiments of the present invention, and it should be understood that technical features related to the above embodiments and preferred modes thereof can be reasonably combined and configured into various equivalent schemes by those skilled in the art without departing from and changing the design idea and technical effects of the present invention; therefore, the invention is not limited to the embodiments shown in the drawings, and all the modifications and equivalent embodiments that can be made according to the idea of the invention are within the scope of the invention as long as they are not beyond the spirit of the description and the drawings.