Simulation design method of direct-current torque motor leaf spring

Abstract

A simulation design method for a direct current torque motor leaf spring comprises the steps that Maxwell simulation software is used for building a simulation model of a motor, and after simulation operation is conducted, the design pressure value F1 of an electric brush is calculated; according to the design length L and the bending angle alpha of the spring piece, the actual pressure value F2 of a plurality of electric brushes is calculated through simulation, and the length and the bending angle of the spring corresponding to the minimum difference value of F2 and F1 are selected as design parameter values of the spring piece. Through the spring pieces designed by the invention, the pressure of the spring pieces is close to an upper limit value, so that the contact between the electric brush and the commutator is firmer, when the motor rotates at a constant speed, the driving torque and the resistance torque are balanced, and the efficiency and the stability of the motor are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of permanent magnet DC torque motor, and particularly relates to a simulation design method of spring sheet of DC torque motor. BACKGROUND

[0002] Permanent magnet DC torque motor is a DC motor with permanent magnet to establish excitation magnetic field. The motor mainly consists of stator, rotor and brush. During the operation of the motor, when the driving torque and resistance reach balance, the motor rotates at a constant speed. If the resistance torque increases, the efficiency will decrease and the motor will heat up. Conversely, if the resistance torque decreases, the output of the motor may become unstable. Therefore, it is very important to strictly control the resistance torque of the motor to improve the efficiency and stability of the motor.

[0003] The resistance torque of brush permanent magnet DC torque motor mainly consists of friction torque caused by shaft system friction, friction torque caused by the contact between brush and commutator, and magnetic resistance torque caused by slot effect. Among them, the friction torque caused by the contact between brush and commutator accounts for a larger proportion than the other two parts. Therefore, under the requirements of product starting voltage and resistance torque, the brush pressure is controlled in the maximum range to ensure the stability of the contact between brush and commutator, so as to stabilize the friction torque of brush assembly within a certain range and reduce the fluctuation range during rotation, which is an effective way to control the resistance torque of the motor.

[0004] The brush is a transition component for conducting electricity between the rotating part and the fixed part of the motor, which consists of brush holder, brush head and spring sheet. The spring sheet is pressed on the surface of the commutator by a certain pressure applied by the spring sheet, and the brush and the commutator surface form a sliding contact during the operation of the motor. As a kind of elastic element, the spring sheet will deform after being loaded due to its elastic effect. If the spring sheet pressure is not designed reasonably, especially after experiencing vibration, impact and other environmental tests, the brush pressure will be unstable, which will cause unstable contact between the brush and the commutator, and make the motor resistance torque fluctuate. SUMMARY

[0005] In order to solve the above problems existing in the prior art, the present application provides a simulation design method of spring sheet of DC torque motor.

[0006] The technical solutions of the present application: the present application simulates and designs a motor according to design parameters, and calculates the theoretical pressure value of the brush by using a calculation formula. By changing the length and / or bending angle of the spring multiple times, simulation calculation is performed to obtain multiple actual brush pressure values, and the length and bending angle of the spring corresponding to the actual brush pressure value closest to the design brush pressure value are selected to determine the size of the spring sheet. The spring sheet designed by the method tends to the upper limit value of the spring sheet pressure under the premise of meeting the technical index, so that the motor driving torque and the resistance torque are balanced, and the efficiency and stability of the motor are improved. The specific scheme is as follows: a simulation design method of a DC torque motor spring sheet, characterized in that it comprises the following steps:

[0007] S1, calculating the design pressure value F1 of the brush;

[0008] S1.1, using Maxwell simulation software, constructing a simulation model of a DC torque motor, inputting the stator material and inner and outer diameter parameters, the rotor material and inner and outer diameter parameters, the magnetic steel brand and size parameters, the tooth slot size parameters, and the winding parameters according to the design requirements, and performing simulation operation to obtain the simulation value M of the tooth slot torque c ;

[0009] S1.2, calculating the friction torque M caused by the friction of the motor shaft system k , and the mechanical load torque M driven by the motor L ; and combining the resistance torque value M of the motor design requirement, calculating the brush friction torque value M f =M-M c -M k -M L ;

[0010] S1.3, according to the motor rotor radius value r, calculating the brush assembly friction force F f =M f / r;

[0011] S1.4, according to the brush head and commutator material selected by design, determining the friction coefficient μ, and calculating the design pressure value F1 of the brush F1=F f / μ;

[0012] S2, according to the selected spring sheet material, determining the elastic modulus E and allowable stress σ of the spring sheet, inputting the initial design length L and bending angle α of the spring sheet into the simulation model constructed by S1, performing simulation operation, and measuring the brush head displacement δ 初 in the simulation model, and calculating the actual pressure value of the brush, denoted by F2;

[0013] S3, calculating the difference F3 between F1 and F2 F3=F2-F1;

[0014] S4, change the length L and / or the bending angle a of the spring sheet, repeat the steps S2-S3, and obtain a plurality of difference values F3;

[0015] S5, compare the numerical values of the plurality of difference values F3, find the minimum value F3, determine the corresponding F2, and select the length L, the bending angle a, the width b, and the thickness h of the spring sheet corresponding to F2.

[0016] Further, the calculation method of F2 in S2 is as follows:

[0017] S2.1, E, σ, L, δ 初 are substituted into the characteristic formula of the elastic device The thickness of the spring sheet is calculated, and is denoted by h1;

[0018] S2.2, F1, L, σ, h1 are substituted into the strength formula of the elastic device The width of the spring sheet is calculated, and is denoted by b1;

[0019] S2.3, the width and thickness of the spring sheet are set to b1 and h1 respectively, the motor is simulated under no-load, and the brush head displacement δ is measured after running 跑 .

[0020] S2.4, h1, b1, L, δ 跑 , E are substituted into the formula derived from the combination of the characteristic formula of the elastic device and the strength formula of the elastic device The actual pressure value F2 of the brush is calculated.

[0021] The beneficial effects of the present application are as follows: through the spring sheet designed in the present application, the spring sheet pressure is close to the upper limit value, so that the contact between the brush and the commutator is more reliable, when the motor rotates at a constant speed, the driving torque and the resistance torque reach a balance, and the efficiency and stability of the motor are improved.

[0022] Figure 1 is a schematic view of the brush structure of the present application;

[0023] Figure 2 is a schematic view of the brush friction pair structure of the present application;

[0024] Figure 3 is a schematic view of the spring sheet structure of the present application;

[0025] Figure 4 is a flow chart of the spring sheet simulation design of the present application.

[0026] The accompanying drawings are as follows: brush holder 1, brush head 2, spring sheet 3, commutator 4. DETAILED DESCRIPTION

[0027] The present application will be described in detail below in conjunction with specific embodiments.

[0028] In this embodiment, the motor design requirements: resistance torque M≤0.011 N·m at no load.

[0029] S1, using Maxwell simulation software, build the simulation model of the motor, according to the design requirements input stator material and inner and outer diameter parameters, rotor material and inner and outer diameter parameters, magnet grade and size parameters, tooth size parameters, winding parameters, simulation operation, calculate the tooth slot torque M c The value is 0.06 mN·m;

[0030] S2, using the shaft bearing matching method and matching tolerance, the shaft friction torque M of the motor is calculated k The value is 4.5 mN·m, the resistance torque M≤0.011 N·m at no load, the mechanical load torque M of the design requirements L The value is 0, substitute M f =M-M c -M k -M L , the maximum value of the brush assembly friction torque M f 0.00644 N·m;

[0031] S3, the rotor radius r is 44 mm, M f , r is substituted into the torque formula F f =M f / r, the maximum value of the brush assembly friction F f about 0.14 N;

[0032] S4, the brush head material is silver graphite, the commutator material is brass, the contact pair friction coefficient μ formed by the brush head and the commutator is about 0.5, F f , μ is substituted into the mechanics formula F=F f / μ, the maximum value of the brush design pressure F1 is 0.28 N;

[0033] S5, the spring sheet material is beryllium bronze strip QBe2, the value of the material elastic modulus E is 128 GPa, the value of the allowable stress σ is 320 MPa, the spring sheet length L is 9.2 mm, the bending angle α is 138°, in the simulation model constructed in S1, the length L and the bending angle α of the spring sheet are input, the simulation operation is carried out, and the brush head displacement δ 初 1.45 mm;

[0034] S6, the values of the aforementioned E, σ, L, δ 初 are substituted into the characteristic formula of the elastic device The thickness h1 of the spring sheet is about 0.15 mm;

[0035] S7, substituting the numerical values of F1, L, σ, h1 into the strength formula of the elastic device The width b1 of the spring sheet is calculated to be about 2.2 mm;

[0036] S8, inputting the numerical values of the width b1 and the thickness h1 of the spring sheet into the simulation model constructed in S1. The motor is simulated under no-load condition, and the brush head displacement δ is measured after running 跑 1.05 mm;

[0037] S9, substituting the numerical values of h1, b1, L, δ 跑 , E into the formula The actual pressure value F2 of the brush is calculated to be 0.32 N;

[0038] S10, calculating the difference F3 between F1 and F2, F3 = 0.32 N - 0.28 N = 0.04 N;

[0039] S11, changing the length L of the spring sheet to 9.4 mm, inputting the above parameter values into S5 for simulation operation, and measuring the brush head displacement δ to be 1.455 mm. The steps S6-S10 are repeated, and h2 and b2 are calculated to be 0.156 mm and 2.25 mm respectively, F2 is 0.3 N, and F3 is 0.02 N;

[0040] S12, changing the length L of the spring sheet to 9.6 mm, inputting the above parameter values into S5 for simulation operation, and measuring the brush head displacement δ to be 1.47 mm. The steps S6-S10 are repeated, and h3 and b3 are calculated to be 0.15 mm and 2.3 mm respectively, F2 is 0.29 N, and F3 is 0.01 N;

[0041] S12, comparing the numerical values of the three F3, and selecting the numerical value of F2 corresponding to the minimum numerical value of F3. In this embodiment, the numerical value of F3 selected is 0.01 N, and the spring sheet size parameters are determined according to the numerical value of F2 corresponding thereto: the length L is 9.6 mm, the width b is 2.3 mm, the thickness h is 0.15 mm, and the bending angle α is 138°.

[0042] The above is a further detailed description of the present application in combination with a specific preferred embodiment, and the specific implementation of the present application should not be limited to these descriptions. For ordinary skilled persons in the technical field to which the present application belongs, a number of simple deductions or substitutions can be made without departing from the concept of the present application, and all of them should be regarded as falling within the protection scope of the present application.

Claims

1. A method for simulation design of a spring sheet of a direct current torque motor, characterized in that The method comprises the following steps: S1, calculating a design pressure value F1 of the brush; S1.1, using Maxwell simulation software, a simulation model of the direct current torque motor is constructed, the stator material and the inner and outer diameter parameters, the rotor material and the inner and outer diameter parameters, the magnetic steel brand and the size parameters, the tooth slot size parameters, the winding parameters are input according to the design requirements, the simulation operation is carried out to obtain the simulation value M of the tooth slot torque c ; S1.2, calculate the friction torque M caused by the friction of the motor shaft system using existing methods k , and the mechanical load torque M driven by the motor L ; combined with the resistance torque value M required by the motor design, calculate the brush friction torque value M f = M - M c - M k - M L ; S1.3, according to the motor rotor radius value r, calculate the brush assembly friction force F f = M f / r; S1.4, Based on the selected brush head and commutator materials, determine the friction coefficient μ, and calculate the design pressure value F1 = F f / μ; S2, according to the selected spring sheet material, determine the elastic modulus E and allowable stress σ of the spring sheet, using the simulation model constructed by S1, input the initial design length L and bending angle α of the spring sheet, perform simulation operation, and measure the brush head displacement δ in the simulation model 初 , calculate the actual pressure value of the brush, denoted by F2; S3, calculating a difference value F3=F2-F1 between F1 and F2; S4, changing the length L and / or the bending angle α of the spring sheet, repeating the steps S2-S3 to obtain a plurality of difference values F3; S5, comparing the numerical values of the plurality of difference values F3, finding the minimum value F3, determining the corresponding F2, and selecting the length L, the bending angle α, the width b and the thickness h of the spring sheet corresponding to F2.

2. The simulation design method of the spring sheet of the direct current torque motor according to claim 1, characterized in that The calculation method of F2 in S2 is as follows: S2.1, E, σ, L, δ 初 Substitute the characteristic equation of the elastic device The thickness of the spring leaf is calculated and represented by h1; S2.2, substituting F1, L, σ, h1 into the strength formula of the elastic device The width of the spring leaf is calculated as b1. S2.3, set the spring piece width and thickness as b1 and h1 respectively, simulate the motor under no-load, run and then measure the brush head displacement δ 跑 . S2.4, h1, b1, L, δ 跑 , E are substituted into a formula derived from a combination of a characteristic formula of the elastic device and a strength formula of the elastic device The actual pressure value F2 of the brush is calculated.

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