阅读说明：本技术 一种柴油机功率估计方法 (Diesel engine power estimation method ) 是由 刘艳斌 乔新勇 董意 张小明 靳莹 张少亮 于 2021-08-20 设计创作，主要内容包括：本发明还公开一种柴油机功率估计方法,根据柴油机喷油装置结构以及供油原理得到加油齿杆与耗油量的对应关系；根据柴油机不供油状态减速过程估计柴油机规定转速下的机械损失功率；在已知耗油量、空负荷油耗及机械损失功率前提下,通过油耗线法估计当前耗流量或加油齿杆位置及转速下的柴油机输出功率。该方法克服了实车测试柴油机输出功率时传感器安装困难、信号质量差等问题,同时利用了柴油机当前运行工况,可实现柴油机输出功率的实时估计。(The invention also discloses a diesel engine power estimation method, which obtains the corresponding relation between the oiling rack bar and the oil consumption according to the structure of the diesel engine oil injection device and the oil supply principle; estimating mechanical loss power of the diesel engine at a specified rotating speed according to the deceleration process of the diesel engine in the non-oil supply state; on the premise of known oil consumption, idle load oil consumption and mechanical power loss, the current oil consumption or the diesel engine output power at the position and the rotating speed of the oiling toothed bar is estimated by an oil consumption line method. The method overcomes the problems of difficult installation of the sensor, poor signal quality and the like when the output power of the diesel engine is tested in a real vehicle, and can realize the real-time estimation of the output power of the diesel engine by utilizing the current operation condition of the diesel engine.)

1. A diesel engine power estimation method is characterized by comprising the following steps:

step one, collecting the rotating speed of a diesel engine and the position of an oiling toothed bar;

step two, obtaining the fuel consumption of the diesel engine in unit time according to the rotating speed of the diesel engine and the displacement of the oiling rack rod:

in the formula, B is the fuel consumption of the diesel engine in unit time, r is the rotating speed of the diesel engine, H is a plunger parameter, s is the displacement of an oiling toothed bar, B is a constant, D is the diameter of a plunger, and D is the diameter of a gear ring of an oiling group;

and simultaneously obtaining mechanical loss power of the diesel engine:

P_m＝T_tω；

in the formula, P_mFor mechanical power loss of diesel engines, T_tMechanical loss torque of the diesel engine, and omega is crankshaft angular velocity;

step three, calculating to obtain the effective output power of the diesel engine:

in the formula, B_A1For hourly fuel consumption, B_B1The fuel consumption in the idle condition of the diesel engine is small, P_mFor mechanical loss of power, P_eA1For oil consumption of B_A1The effective output power of the diesel engine.

2. The diesel engine power estimation method of claim 1, wherein the mechanical loss torque of the diesel engine is calculated by the formula:

wherein J is the rotational inertia of the rotating part of the diesel engine,is the crankshaft angular acceleration.

3. The diesel power estimation method of claim 2, wherein at a fixed speed for the diesel engine:

in the formula, T₀Is the torque at the fixed rotational speed,the angular acceleration of the crankshaft at a fixed rotational speed.

4. The diesel engine power estimation method according to claim 3, wherein the mechanical loss torque of the diesel engine satisfies:

5. the diesel power estimation method of claim 4, wherein the hourly fuel consumption satisfies:

in the formula, B_A1For hourly fuel consumption, H_uIs the heat value of diesel oil eta_itTo indicate thermal efficiency, P_eA1For oil consumption of B_A1The effective output power of the diesel engine.

6. The diesel power estimation method of claim 5, wherein the fuel consumption amount at the time of the idle condition of the diesel engine satisfies:

7. the diesel power estimation method of claim 1, wherein the constant satisfies:

wherein H' is the total height of the plunger helical line theta₀The angle occupied by the projection of the spiral line on the top surface of the plunger piston.

Technical Field

The invention relates to the technical field of diesel engines, in particular to a diesel engine power estimation method.

Background

The power is the work done (consumed) in unit time of the power machine machinery, any active machinery has output power, the gasoline engine and the electric motor are both provided, the diesel engine is no exception, and the output power of the diesel engine is an important index for representing the technical state of the diesel engine.

In the prior art, there are two general methods for testing the power of a diesel engine, namely a method of testing through a test bench and a method of testing by a real vehicle.

In the equipment service phase, the method based on the bench test is difficult to implement.

The real vehicle testing method is to install a sensor on a real vehicle for testing, and often a strain gauge is installed between a power output end of a diesel engine and a coupler to measure output torque, so as to calculate power.

However, with the application of the power transmission integration technology, the diesel engine and the transmission device are integrated into a whole, and a torque sensor is not installed in a space, so that the problems of difficult installation of the sensor, poor signal quality and the like when the diesel engine output power is tested in a real vehicle can occur, and the measurement of the diesel engine output power under the real vehicle condition becomes a difficult point.

Disclosure of Invention

The invention designs and develops a diesel engine power estimation method, which obtains the oil consumption per unit time under different working conditions according to the position of a refueling rack of a diesel engine, and obtains the output power of the diesel engine according to the oil consumption per unit time, the oil consumption per unit time of an idle load and the mechanical loss power, thereby improving the accuracy and the estimation efficiency.

The technical scheme provided by the invention is as follows:

a diesel engine power estimation method comprises the following steps:

step one, collecting the rotating speed of a diesel engine and the position of an oiling toothed bar;

step two, obtaining the fuel consumption of the diesel engine in unit time according to the rotating speed of the diesel engine and the displacement of the oiling rack rod:

in the formula, B is the fuel consumption of the diesel engine in unit time, r is the rotating speed of the diesel engine, H is a plunger parameter, s is the displacement of an oiling toothed bar, B is a constant, D is the diameter of a plunger, and D is the diameter of a gear ring of an oiling group;

and simultaneously obtaining mechanical loss power of the diesel engine:

P_m＝T_tω；

in the formula, P_mFor mechanical power loss of diesel engines, T_tMechanical loss torque of the diesel engine, and omega is crankshaft angular velocity;

step three, calculating to obtain the effective output power of the diesel engine:

in the formula, B_A1For hourly fuel consumption, B_B1The fuel consumption in the idle condition of the diesel engine is small, P_mFor mechanical loss of power, P_eA1For oil consumption of B_A1The effective output power of the diesel engine.

Preferably, the mechanical loss torque of the diesel engine is calculated by the formula:

wherein J is the rotational inertia of the rotating part of the diesel engine,is the crankshaft angular acceleration.

Preferably, the following is satisfied for a diesel engine at a fixed speed:

in the formula, T₀Is the torque at the fixed rotational speed,the angular acceleration of the crankshaft at a fixed rotational speed.

Preferably, the mechanical loss torque of the diesel engine satisfies:

preferably, the hourly fuel consumption satisfies:

in the formula, B_A1For hourly fuel consumption, H_uIs the heat value of diesel oil eta_itTo indicate thermal efficiency, P_eA1For oil consumption of B_A1The effective output power of the diesel engine.

Preferably, the fuel consumption when the idle speed condition of the diesel engine is small meets the following requirements:

preferably, the constant satisfies:

wherein H' is the total height of the plunger helical line theta₀The angle occupied by the projection of the spiral line on the top surface of the plunger piston.

The invention has the following beneficial effects:

(1) the method for estimating the power of the diesel engine solves the problems of difficult sensor installation, poor signal quality and the like when the diesel engine is tested in a real vehicle due to high integration of the diesel engine and a transmission device of the vehicle, and improves the practicability and convenience of estimating the power of the diesel engine.

(2) The diesel engine power estimation method provided by the invention integrates the characteristic information of mechanical power loss, empty load oil consumption and the like during the use period of the diesel engine, and improves the accuracy of diesel engine power estimation.

Drawings

Fig. 1 is a schematic flow chart of a diesel engine power estimation method according to the present invention.

Fig. 2 is a schematic diagram of a plunger structure of the diesel engine.

FIG. 3 is a graph comparing measured external characteristics to calculated power according to the present invention.

Detailed Description

The present invention is further described in detail below with reference to the attached drawings so that those skilled in the art can implement the invention by referring to the description text.

As shown in fig. 1, the present invention provides a method for estimating power of a diesel engine, comprising the following steps:

as shown in fig. 2, the plunger and barrel assembly of the oil supply unit of the diesel engine injection pump, the plunger opening oil return hole cutting edge is a spiral cutting edge, and the relation between the effective oil supply stroke and the plunger rotation angle can be obtained according to the spiral equation:

h₀＝H+bθ

in the formula, h₀For the effective oil supply stroke of the plunger, H is a plunger parameter, theta is a rotation angle of the plunger, b is a constant and satisfies:

wherein H' is the total height of the plunger helical line theta₀The angle occupied by the projection of the spiral line on the top surface of the plunger piston.

The oil supply gear ring of the oil injection pump is fixed with the plunger, and the relationship between the rotating angle of the plunger and the displacement of the oil filling rack can be determined according to the corresponding relationship between the oil filling rack and the oil injection pump gear ring:

in the formula, s is the displacement of the oil filling gear rod, and D is the diameter of the oil supply group gear ring;

the calculation formula of the oil supply quantity of one oil supply group of the oil injection pump in one working cycle of the engine is as follows:

in the formula, q₀The oil supply quantity of an oil supply group of the oil injection pump in one working cycle of the engine is d, and the diameter of the plunger is d;

the fuel consumption of the diesel engine per unit time is as follows:

in the formula, B is the fuel consumption of the diesel engine in unit time, and r is the rotating speed of the diesel engine;

therefore, the relationship between the fuel consumption of the diesel engine per unit time and the displacement of the rack bar can be obtained:

according to the theorem of moment of momentum:

Jω＝T_tt；

in the formula, J is the rotational inertia of a rotating part of the diesel engine; omega is the crankshaft angular velocity when the diesel engine decelerates from a high rotating speed to a certain fixed rotating speed under the condition of no oil supply, unit: rad/s; t is_tThe mechanical loss torque of a diesel engine at a certain fixed rotating speed in the service period is represented by the unit: n.m; t is time, unit: second;

this gives:

in the formula (I), the compound is shown in the specification,the unit is the crankshaft angular acceleration when the diesel engine is decelerated from a high rotating speed to a certain fixed rotating speed under the condition of no oil supply in the service period: rad/s²。

Torque T of a certain fixed rotation speed when the diesel engine leaves the factory₀And angular accelerationSubstituting into the formula:

in the formula, T₀Is the torque when the rotating speed of the diesel engine which is newly delivered from a factory is fixed,the crankshaft angular acceleration is the crankshaft angular acceleration when the diesel engine which is newly dispatched from the factory is decelerated from a high rotating speed to a fixed rotating speed under the condition of no oil supply;

because the diesel engine is in a non-oil supply state during testing, the calculated torque is generated by the internal mechanical loss of the diesel engine, and the mechanical loss torque of different service time under the same rotating speed can be obtained by the angular acceleration:

in the formula (I), the compound is shown in the specification,andwhen the diesel engine decelerates from a high rotating speed to a certain fixed rotating speed after oil cut, the engine is obtained by calculating a rotating speed value:

in the formula, Δ n is the speed change of the diesel engine within time Δ t at a fixed rotation speed, which is the calculation method of the acceleration in the deceleration process in fig. 1;

therefore, the mechanical loss power of different service times at the same rotating speed can be obtained:

P_m＝T_tω；

in the formula, P_mPower is lost mechanically.

Under the condition that the rotating speed of the internal combustion engine is not changed, the mechanical efficiency and the indicated thermal efficiency are not changed along with the change of the load, so that for any operating point of the diesel engine, the following operating points are provided:

B_A1H_uη_it＝3600P_i＝3600(P_eA1+P_m)；

in the formula, B_A1For hourly fuel consumption, H_uIs the heat value of diesel oil eta_itTo indicate thermal efficiency, P_iIndicating power, P, for diesel engines_eA1For oil consumption of B_A1Effective output power of the diesel engine;

the idle working condition of the diesel engine comprises the following steps:

B_B1H_uη_it＝3600P_m；

in the formula, B_B1The fuel consumption is small under the idling condition of the diesel engine;

thus, it is possible to obtain:

therefore, the fuel consumption of the diesel engine under the idle working condition is calculated and obtained through the fuel consumption formula of the diesel engine per unit time, the mechanical loss power is obtained through the formula, and when the fuel consumption of the diesel engine under any working condition is known, the corresponding fuel consumption B can be obtained_A1The effective output power of the diesel engine.

Examples

According to the estimation method, taking a certain diesel engine new machine as an example, the diameter of a plunger of the certain diesel engine is 10mm, the parameter of the plunger is 2.74mm, the constant is 1.122, the diameter of a gear ring is 28.6mm, the fixed rotating speed is determined to be 1500r/min, the mechanical loss efficiency of the new diesel engine new machine is 17.1KW, the oil filling rack displacement is detected to be 3mm through the idle load operation of the diesel engine, the idle load oil consumption is calculated to be 0.874g/s, the oil filling rack displacement of the diesel engine at the maximum oil filling position at 1500r/min is 15mm, the maximum oil supply is calculated to be 15.8g/s, and the calculated power value is 292.1 KW. Comparing the calculated power value with an external characteristic diagram, such as that shown in fig. 3, wherein the abscissa represents the diesel engine speed and the ordinate represents the diesel engine power; the round point in the graph is a power value corresponding to the rotating speed of 1500r/min, the curve represents the change rule of the power of a certain diesel engine along with the rotating speed, and the power obtained by calculation according to the rotating speed and the position of the oiling toothed bar is more consistent with the actually measured external characteristic power of the engine rack.

The diesel engine power estimation method provided by the invention integrates the characteristic information of mechanical power loss, empty load oil consumption and the like during the use period of the diesel engine, and improves the accuracy of diesel engine power estimation.

While embodiments of the invention have been described above, it is not limited to the applications set forth in the description and the embodiments, which are fully applicable in various fields of endeavor to which the invention pertains, and further modifications may readily be made by those skilled in the art, it being understood that the invention is not limited to the details shown and described herein without departing from the general concept defined by the appended claims and their equivalents.