Piston pump motor dynamics model single working condition piston cavity leakage coefficient calibration method

Abstract

The present application belongs to the technical field of hydraulic components, and particularly relates to a single working condition plunger cavity external leakage coefficient calibration method for a plunger pump motor dynamics model, which regards the plunger cavity external leakage coefficient as a quantity affected by working conditions, and through analyzing plunger pump motor test data and plunger pump motor dynamics model simulation data, makes the simulation speed ratio obtained by plunger pump motor dynamics model calculation approximate the actual speed ratio to the greatest extent, and calibrates the plunger cavity external leakage coefficient under a certain working condition by using an optimization algorithm. The single working condition plunger cavity external leakage coefficient calibration method for a plunger pump motor dynamics model disclosed by the present application has the advantages of high precision, small amount of calculation, high efficiency and the like.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic component technology, specifically relating to a method for calibrating the external leakage coefficient of the piston cavity under a single working condition in a piston pump motor dynamic model. Background Technology

[0002] During operation, the piston chamber of a plunger pump motor leaks oil into the pump motor housing simultaneously through four friction pairs: the distribution pair, the piston pair, the slipper pair, and the ball joint pair. This directly affects the pre-pressurization and pre-depressurization processes of the piston chamber. Therefore, studying the external leakage characteristics of the piston chamber in a plunger pump motor is crucial for understanding the distribution characteristics of the plunger pump motor. Existing research reports simplify the external leakage of the piston chamber in plunger pump motors to a fixed-clearance oil film leakage. However, in reality, the thickness and shape of the oil film in the friction pair clearance are not fixed and vary with operating conditions. Therefore, treating the friction pair oil film as a fixed-clearance oil film cannot accurately reflect the impact of changes in operating parameters on the external leakage characteristics of the piston chamber.

[0003] To more accurately describe the external leakage characteristics of the plunger cavity in a plunger pump, if the external leakage coefficient of the plunger cavity is defined as a function considering the operating conditions, then lubrication models of the oil film gaps in the four major friction pairs—distribution pair, plunger pair, slipper pair, and ball joint pair—can be established based on the Reynolds equation describing the oil film state and the dynamic equilibrium equation describing the motion attitude of the friction pair components. Coupled solutions can then be obtained to acquire the external leakage coefficient of the plunger cavity under various operating conditions. However, this coupled solution process involves a huge computational burden, and suppressing the solution error of the partial differential equations is difficult. Therefore, if the external leakage coefficient of the plunger cavity under different operating conditions can be calibrated using experimental data from the plunger pump motor, the simulation accuracy of the pump motor dynamic model across the entire operating range can be significantly improved, thus increasing simulation efficiency. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] The technical problem this invention aims to solve is: to address the difficulty in calculating the external leakage coefficient of the plunger cavity under different operating conditions of a pump motor, this invention provides a single-condition calibration method for the external leakage coefficient of the plunger cavity in a plunger pump motor dynamic model. This method treats the external leakage coefficient as a quantity affected by operating conditions, and by analyzing experimental data and simulation data from the plunger pump motor dynamic model, it aims to maximize the approximation of the actual speed ratio obtained from the model. An optimization algorithm is then used to calibrate the external leakage coefficient under a specific operating condition, thereby improving the simulation accuracy and efficiency of the plunger pump motor dynamic model across the entire operating range.

[0006] (II) Technical Solution

[0007] To address the aforementioned technical problems, this invention provides a method for calibrating the external leakage coefficient of the piston cavity under a single operating condition in a piston pump motor dynamic model. The method calibrates the external leakage coefficient K of the piston cavity. ou

[0008] Considered as a quantity affected by operating conditions, let m be the actual speed ratio of the piston pump motor under operating condition.

[0009] The measured motor speed n of the pump at maximum displacement. m With pump speed n p The ratio of the simulated speed ratio of the plunger pump motor to the external leakage coefficient K is given by the ratio of the external leakage coefficient K to the speed ratio of the plunger pump motor to the speed ratio of the simulated speed ratio of the plunger pump motor to the speed ... simulated speed ratio of the plunger pump motor to the speed ratio of the simulated speed ratio of the plunger pump motor to the ou Substituting the speed ratio obtained from the piston pump motor dynamics model calculation, the calibration error Ψ(K) of the simulated speed ratio ratio is... ou )for:

[0010] ψ(K ou )=|ratio-ratio * | (1)

[0011] Where m represents any operating condition of the plunger pump motor;

[0012] To make the ratio approximate the actual speed ratio ratio* as closely as possible, make Ψ(K ou ) = 0, and solve Ψ(K) using the iterative method of equation (2). ou ) = 0:

[0013]

[0014] Right now:

[0015]

[0016] Among them, K ou,n+1 K ou,n K ou,n-1 K ou The (n+1), n, and n-1th iteration values, Ψ(K) ou，n ) and Ψ(K ou，n-1 ) represent K under working condition m respectively. ou,n and K ou,n-1 The simulated speed ratio obtained by substituting into the dynamic model of the piston pump motor is ratio n and ratio n-1 The calibration error.

[0017] The method for calibrating the external leakage coefficient of the plunger cavity under single-condition operation of the plunger pump motor dynamic model includes the following steps:

[0018] Step 1: Calculate the actual speed ratio * of the piston pump motor under operating condition m, where the motor speed and pump speed under operating condition m are respectively n m and n p ;

[0019] Step 2: Determine the initial value K of the external leakage coefficient of the plunger cavity. ou,0 K ou,1 And the accuracy requirement ε, where K ou,0 and K ou,1 It is any constant greater than 0, and ε is a positive number close to 0;

[0020] Step 3: Place K ou,0 and K ou,1 Substitute the piston pump motor dynamics model and calculate its corresponding simulated speed ratios ratio0 and ratio1.

[0021] Step 4: n = 1, calculate K according to equation (3) ou,2 where n is a positive integer;

[0022] Step 5: Place K ou,2 Substituting into the dynamic model of the piston pump motor, the corresponding simulated speed ratio ratio2 is calculated, and its calibration error Ψ(K) is calculated according to equation (1). ou,2 );

[0023] Step 6: Determine the calibration error Ψ(K) ou,2 If the value is less than or equal to the precision requirement ε, then output K. ou At this time, K ou =K ou,2 If the error exceeds the accuracy requirement ε, return to step 4 and increment n by 1. Repeat steps 4-6 until the calibration error Ψ(K) is reached. ou,n+1 If the accuracy requirement ε is less than ε, the output K will be less than ε. ou At this time, K ou =K ou,n+1 Finally, the single-condition external leakage coefficient K of the plunger cavity of the plunger pump motor dynamic model was completed. ou The calibration.

[0024] The plunger pump motor dynamics model can be any existing plunger pump motor dynamics model.

[0025] (III) Beneficial Effects

[0026] Compared with the prior art, the present invention has the following beneficial effects: A method for calibrating the external leakage coefficient of the plunger cavity in a single-condition plunger pump motor dynamic model, wherein the external leakage coefficient K of the plunger cavity is... ouThe external leakage coefficient of the plunger cavity is considered to be affected by the working conditions, making it closer to the actual value and improving the accuracy of the model. The calibration of the external leakage coefficient of the plunger cavity is based on the goal of ensuring that the simulation speed obtained from the dynamic model of the plunger pump motor meets the accuracy requirements. The cyclic optimization method is used to solve the problem, which greatly reduces the amount of calculation and shortens the calibration time of the external leakage coefficient of the plunger cavity. Attached Figure Description

[0027] Figure 1 This is a flowchart of the calibration process for the external leakage coefficient of the plunger cavity under a single working condition in the dynamic model of the plunger pump motor of the present invention. Detailed Implementation

[0028] To make the objectives, contents, and advantages of the present invention clearer, the specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0029] To address the problems in existing technologies, this invention proposes that the external leakage characteristics of the plunger cavity in a plunger pump motor not only significantly affect the flow distribution characteristics of the plunger pump motor but also directly determine its volumetric efficiency. For integrated plunger pump motors, since the volumetric efficiency of a single pump and a single motor is difficult to measure, the speed ratio is typically used to indirectly characterize the overall volumetric efficiency of the pump and motor. Therefore, by adjusting the external leakage coefficient of the plunger cavity, the simulated speed ratio calculated by the plunger pump motor dynamic model is made to approximate the measured speed ratio with a certain accuracy requirement, serving as the calibration basis for the external leakage coefficient of the plunger cavity under various operating conditions.

[0030] A method for calibrating the external leakage coefficient of the plunger cavity under single-condition operation in a plunger pump motor dynamic model, wherein the external leakage coefficient K of the plunger cavity is... ou Considered as a quantity affected by operating conditions, let m be the actual speed ratio of the piston pump motor under operating condition, and ratio* be the measured motor speed n at the pump's maximum displacement. m With pump speed n p The simulated speed ratio of the plunger pump motor is: The external leakage coefficient K of the plunger cavity is... ou Substituting the speed ratio obtained from the piston pump motor dynamics model calculation, the calibration error Ψ(K) of the simulated speed ratio ratio is... ou )for:

[0031] The calibration error Ψ(K) of the simulated speed ratio ou )for:

[0032] ψ(K ou )=|ratio-ratio * | (1)

[0033] Where m represents any operating condition of the plunger pump motor;

[0034] To make the ratio approximate the actual speed ratio ratio* as closely as possible, make Ψ(K ou ) = 0, and solve Ψ(K) using the iterative method of equation (2). ou ) = 0:

[0035]

[0036] Right now:

[0037]

[0038] Among them, K ou,n+1 K ou,n K ou,n-1 K ou The (n+1), n, and n-1th iteration values, Ψ(K) ou，n ) and Ψ(K ou，n-1 ) represent K under working condition m respectively. ou,n and K ou,n-1 The simulated speed ratio obtained by substituting into the dynamic model of the piston pump motor is ratio n and ratio n-1 The calibration error;

[0039] The calibration of the external leakage coefficient of the plunger cavity under a single operating condition in the dynamic model of the plunger pump motor is performed using the following steps:

[0040] Step 1: Calculate the actual speed ratio * of the piston pump motor under operating condition m, where the motor speed and pump speed under operating condition m are respectively n m and n p ;

[0041] Step 2: Determine the initial value K of the external leakage coefficient of the plunger cavity. ou,0 K ou,1 And the accuracy requirement ε, where K ou,0 and K ou,1 It is any constant greater than 0, and ε is a positive number close to 0;

[0042] Step 3: Place K ou,0 and K ou,1 Substitute the piston pump motor dynamics model and calculate its corresponding simulated speed ratios ratio0 and ratio1.

[0043] Step 4: n = 1, calculate K according to equation (3) ou,2 where n is a positive integer;

[0044] Step 5: Place K ou,2 Substituting into the dynamic model of the piston pump motor, the corresponding simulated speed ratio ratio2 is calculated, and its calibration error Ψ(K) is calculated according to equation (1). ou,2 );

[0045] Step 6: Determine the calibration error Ψ(K) ou,2 If the value is less than or equal to the precision requirement ε, then output K. ou At this time, K ou =K ou,2 If the error exceeds the accuracy requirement ε, return to step 4 and increment n by 1. Repeat steps 4-6 until the calibration error Ψ(K) is reached. ou,n+1 If the accuracy requirement ε is less than ε, the output K will be less than ε. ou At this time, K ou =K ou,n+1 Finally, the single-condition external leakage coefficient K of the plunger cavity of the plunger pump motor dynamic model was completed. ou The calibration.

[0046] The plunger pump motor dynamics model is any existing plunger pump motor dynamics model.

[0047] Example 1

[0048] Table 1 shows the steady-state characteristics of a 280 ml / r plunger pump motor under 42 different operating conditions at full displacement. The pump speed was controlled around 1000, 2000, and 2800 r / min; the pressure was controlled around 10, 20, 30, 40, and 50 MPa; and the oil replenishment temperature was controlled around 30, 60, and 90 °C. These 42 operating conditions cover a wide range of speed, pressure, and temperature to comprehensively reflect the volumetric efficiency characteristics of the plunger pump motor.

[0049] For the above 42 operating conditions, the external leakage coefficient of the piston cavity of the piston pump motor dynamic model under each single operating condition is calibrated. Taking the 8th operating condition as an example, the following steps are adopted:

[0050] Step 1: Calculate the actual speed ratio of the piston pump motor under the 8th operating condition, ratio* = 90.017%, as shown in Table 2;

[0051] Step 2: Set the initial value K of the external leakage coefficient of the plunger cavity. ou,0 =0.006, K ou,1 =0.09, accuracy requirement ε=0.005;

[0052] Table 1. Actual speed ratio data

[0053]

[0054]

[0055]

[0056] Step 3: Place Kou,0 and K ou,1 Substituting into the dynamic model of the piston pump motor, the corresponding simulated speed ratios ratio0 = 95.07% and ratio1 = 86.11% were calculated;

[0057] Step 4: n = 1, calculate K according to equation (3) ou,2 =0.0534;

[0058] Step 5: Place K ou,2 Substituting into the dynamic model of the piston pump motor, the corresponding simulated speed ratio ratio2 = 90.61% was calculated, and its calibration error Ψ(K) was calculated according to equation (1). ou,2 ) = 0.0059;

[0059] Step 6: Determine the calibration error Ψ(K) ou,2 Whether Ψ(K) is less than the accuracy requirement ε depends on the context. ou,2 Since Ψ(K) = 0.0059, which is greater than 0.005, return to step 4 and increment n by 1. Repeat steps 4-6 until the calibration error Ψ(K) is reached. ou,n If the value is less than 0.005, the external leakage coefficient of the plunger cavity under the 8th working condition is 0.0582, thus completing the single-working-condition external leakage coefficient K of the plunger pump motor dynamic model. ou The calibration is shown in Table 2.

[0060] Table 2 shows the calibration results of the external leakage coefficient of the plunger cavity in the single-condition plunger pump motor dynamic model for all 42 operating conditions. The maximum and minimum calibration errors were 0.477% and 0%, respectively, and the average calibration error was 0.063%. The total calibration time for the 42 operating conditions was only 56.93 hours, with an average calibration time of only 1.35 hours per operating condition. Moreover, this is only the computation time on a regular computer. The calibration method for the external leakage coefficient of the plunger cavity in the single-condition plunger pump motor dynamic model disclosed in this invention ensures calibration efficiency.

[0061] Table 2.42 Calibration results and calibration errors of external leakage coefficient under different operating conditions.

[0062]

[0063]

[0064]

[0065] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for calibrating the external leakage coefficient of the plunger cavity under a single operating condition in a plunger pump motor dynamic model, characterized in that, The method measures the external leakage coefficient K of the plunger cavity. ou Considered as a quantity affected by operating conditions, let m be the actual speed ratio of the piston pump motor under operating condition, and ratio* be the measured motor speed n at the pump's maximum displacement. m With pump speed n p The ratio of the simulated speed ratio of the plunger pump motor to the external leakage coefficient K is given by the ratio of the external leakage coefficient K to the speed ratio of the plunger pump motor to the speed ratio of the simulated speed ratio of the plunger pump motor to the speed ... simulated speed ratio of the plunger pump motor to the speed ratio of the simulated speed ratio of the plunger pump motor to the ou Substituting the speed ratio obtained from the piston pump motor dynamics model calculation, the calibration error Ψ(K) of the simulated speed ratio ratio is... ou )for: ψ(K ou )=|reason-reason * | (1) Where m represents any operating condition of the plunger pump motor; To make the ratio approximate the actual speed ratio ratio* as closely as possible, make Ψ(K ou ) = 0, and solve Ψ(K) using the iterative method of equation (2). ou ) = 0: Right now: Among them, K ou,n+1 K ou,n K ou,n-1 K ou The (n+1), n, and n-1th iteration values, Ψ(K) ou，n ) and Ψ(K ou，n-1 ) represent K under working condition m respectively. ou,n and K ou, The simulated speed ratio obtained by substituting n-1 into the piston pump motor dynamics model is ratio. n and ratio n-1 The calibration error.

2. The method for calibrating the external leakage coefficient of the plunger cavity under single-condition operation of the plunger pump motor dynamic model as described in claim 1, characterized in that, The method for calibrating the external leakage coefficient of the plunger cavity under single-operation condition in the dynamic model of the plunger pump motor adopts the following steps: Step 1: Calculate the actual speed ratio * of the piston pump motor under operating condition m, where the motor speed and pump speed under operating condition m are respectively n m and n p ; Step 2: Determine the initial value K of the external leakage coefficient of the plunger cavity. ou,0 K ou,1 And the accuracy requirement ε, where K ou,0 and K ou,1 It is any constant greater than 0, and ε is a positive number close to 0; Step 3: Place K ou,0 and K ou,1 Substitute the piston pump motor dynamics model and calculate its corresponding simulated speed ratios ratio0 and ratio1. Step 4: n = 1, calculate K according to equation (3) ou,2 where n is a positive integer; Step 5: Place K ou,2 Substituting into the dynamic model of the piston pump motor, the corresponding simulated speed ratio ratio2 is calculated, and its calibration error Ψ(K) is calculated according to equation (1). ou,2 ); Step 6: Determine the calibration error Ψ(K) ou,2 If the value is less than or equal to the precision requirement ε, then output K. ou At this time, K ou =K ou,2 If the error exceeds the accuracy requirement ε, return to step 4 and increment n by 1. Repeat steps 4-6 until the calibration error Ψ(K) is reached. ou,n+1 If the accuracy requirement ε is less than ε, the output K will be less than ε. ou At this time, K ou =K ou,n+1 Finally, the single-condition external leakage coefficient K of the plunger cavity of the plunger pump motor dynamic model was completed. ou The calibration.

3. The method for calibrating the external leakage coefficient of the plunger cavity under single-condition operation of the plunger pump motor dynamic model as described in claim 2, characterized in that, The plunger pump motor dynamics model is any existing plunger pump motor dynamics model.

4. The method for calibrating the external leakage coefficient of the plunger cavity under single-condition operation of the plunger pump motor dynamic model as described in claim 2, characterized in that, m represents any operating condition of the plunger pump motor.

5. The method for calibrating the external leakage coefficient of the plunger cavity under single-condition operation of the plunger pump motor dynamic model as described in claim 2, characterized in that, K ou,n+1 K represents ou The (n+1)th iteration value.

6. The method for calibrating the external leakage coefficient of the plunger cavity under single-condition operation of the plunger pump motor dynamic model as described in claim 2, characterized in that, K ou,n K represents ou The nth iteration value.

7. The method for calibrating the external leakage coefficient of the plunger cavity under single-condition operation of the plunger pump motor dynamic model as described in claim 2, characterized in that, K ou,n-1 K represents ou The (n-1)th iteration value.

8. The method for calibrating the external leakage coefficient of the plunger cavity under single-condition operation of the plunger pump motor dynamic model as described in claim 2, characterized in that, Ψ(K ou，n ) indicates that under working condition m, K ou,n The simulated speed ratio obtained by substituting into the dynamic model of the piston pump motor is ratio n and ratio n-1 The calibration error.

9. The method for calibrating the external leakage coefficient of the plunger cavity under single-condition operation of the plunger pump motor dynamic model as described in claim 2, characterized in that, Ψ(K ou，n-1 ) indicates that under working condition m, K ou,n-1 The simulated speed ratio obtained by substituting into the dynamic model of the piston pump motor is ratio n and ratio n-1 The calibration error.

10. The method for calibrating the external leakage coefficient of the plunger cavity under single-condition operation of the plunger pump motor dynamic model as described in claim 2, characterized in that, The method described belongs to the field of hydraulic component technology.

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