CC BY
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nological resistance caused by the polymer material and grind materials. At the same time, we used the II — Lagrange equations [2]. Thus, we obtained the following system of differential equations:
Mg = 2Mkvc - 2Mip(j)l -acSkMg;
JA = Ms -B()-ci(;
Jik = B(A ) + c 1 (01- 02)-B (2 - k)-c2(2- fa); JA = 02 (^2 - 03 ) + C2 (02 - 03 ) - Mc ,
Where, Mg, Mk - the drive torque of the motor and its critical value; p - Number ofpole pairs; - Circular frequency ofthe network; Sk - Sliding and its critical value; 0P 02, 03 - the angular velocity of the motor, the intermediate shaft and the outer sleeve of the roller; Mc - Technological resistance of polymeric material; cj, c2, B1, B2 - Coefficients of stiffness and damping circular chain drive roller and an elastic sleeve.
The laws of motion of the roller at various initial settingshas been derived based onthe numerical solution of differential equations. The best parameter settings of the drive rollershas been determined.
References:
1. Veselov V. V., Gorbunov I. D., Molkova I. V. Apparatus for applying liquid-phase polymer on sections cut parts. Proceedings of the universities. The technology of the textile industry. - 2007, - No 3. - P. 97-99.
2. Djuraev A. and others. The theory of mechanisms and machines. Ed. "G. Gulyamov". - Tashkent, - 2004. - P. 594.
DOI: http://dx.doi.org/10.20534/ESR-16-11.12-131-134
Kambarov Bahtiyor Akbaralievich, candidate of technical sciences, Laboratory of power, transport and loading and unloading works, Scientific Research Institute of Mechanization and Electrification of Agriculture (SRIMEA), Republic of Uzbekistan, Yangiyul district,
E-mail: b-kambarov@rambler.ru
Method of calculating the kinematic parameters of steering gear ensuring a tractor minimum turning circle radius
Abstract: Calculating the parameters of a portal front axle and the steering gear of the perspective high-clearance cotton growing tractor 4K2 are specified in the article.
Keywords: a four-wheeled cotton growing tractor, front portal high-clearance axle of the steered wheels, the parameters of a front axle, steering linkage, setting angles of the steering gear, a turning angle of the front wheels, a minimum turning radius.
Turning the steering wheels of agricultural tractors in the course of working is performed by the driver by applying the steering control mechanism. If a turn must be sharper, then it is reasonable to use the right or left brake. In this case one of the driving wheels will be decelerated or blocked and then the rear axle differential starts functioning.
The tractor must be operated without much effort on the steering wheel, and for the purpose to maintain the desired track of the turning the guide wheels must move in pure rolling mode, that doesn't slide relative to the supporting face [1, 3-4]. In effort
to facilitate the tractors driving they are equipped with hydraulic amplifying appliances of a steering control and the steering gear parameters will be optimized.
In addition, the quality of tractor driving is ensured by setting the guide wheels at certain angles — the break-up, convergence and steering stubs of bracket supports bending.
Figure 1 shows the classical scheme of the wheel tractors rotation.
On the fig. 1, a a turning scheme of cotton growing tractor having one-wheeled frontal axle.
Fig. 1, b shows a scheme of tractor turning 4K2 (4K4).
а) b)
Figure 1.Turning scheme of wheel tractors 3K2 and 4K2 (4K4)
Pure rolling of the guiding wheels at a tractor turning will be ensured in case if the axes extension of all wheels will crossover at a single point O, so called the turning center. As the tractor wheel-base is shorter, the shorter will be the distance from the turning center R until the middle of the wheels outside track and thus the tractor turning ability will get better, where R minimum trace
o / o ' mtn t. o.w.
the turning radius of the outer wheel.
From Fig. 1, b it is seen that for any value of the turning angle, for example, with respect to the internal driven wheel fi . is always possible to determine the value of turning angle of the outside steering wheel fi , that is,
Ltg Pin
pou = arctg
Mtg pm + L
(1)
where fi and fi — turning angles of the outside and inside steering
r ou r tn O O O
wheels in layout, degrees; L — longitudinal tractor wheelbase, mm; M — a distance between the pivot axes of the turning stub, mm.
In the term (1) the value of M — distance between the pivot is determined by the following formula
M = B-2[a + (A + C) tgy], (2)
where a = ls(cos5-sin 5 tgy)-rtt(sin5+ cos5 tgy), (3)
B — wheel tread of the tractor steering wheels, mm; a — shoulder of wheel running-in test in respect of stub axle, mm; ls — stub axle length, mm; A+C — height of support center of the pivot lever assembly at claw, mm; j — shaft axle elevation angle in the transverse flat surface, degree; S- camber angle of steered wheels, degree; rt — static radius of steered wheels, mm; h- height of steering linkage h = r cos^, mm (Fig. 2.).
a)
b)
c)
Figure 2. Setting parameters if steered wheels (a and b) and the steering linkage (c) of the front axle (bridge) universal tractors.
Value of turning angle of the outside steering wheel calculated by the term (1) may be called theoretical value of this angle P2'.
Above specified regularity (1) is achieved by a steering linkage mechanism that ensures dirigibility and resistance of set direction of tractor movement. Tractor with wrongly designed or improperly adjusted steering trapezia arbitrarily change moving the direction, "yaws" in the field, will react inadequately to the impact of the driver's control activation, which reduces the quality of agro technical works, exceedingly will make the tractor operator to be tired and does not guarantee traffic safety.
Set turning angles of the tractor guiding wheels must be maintained in the course of whole operation. The tractor turning radius,
fU = arctg
maneuverability of a machine, headland width, time consumed for turns and other performance indicators depend on that.
Steering linkage is located in before the frontal axe (Fig. 3, a) or rear (Fig. 3, b).
In effort to get the correct balance between the angles of steered wheels, ensuring the ration constancy of M/L for a particular design of the tractor it is necessary to select out the dimensions of trapezoid elements; coordinating them with the longitudinal wheelbase of the machine; the distance between axes of pivots shafts and steered wheels spacing.
Considering (2) and (3) the expression (1) we can write the following form,
L tg fm
_. (4)
B-2(cosS-sin 5 tgy)-rtt(sin5+ cos5 tgy) + (A + C) tgy1} tgfi in + L
Let's consider steering linkage (Fig. 2, c). Analytical relation- design parameters of the trapezoid are described in the following ship between angles fi.n and fiou the steered wheels turn oftractor and formula [2, 222-226; 3, 408-412; 4, 668-675].
(<t> + Pin) . r + 2M■ sin^-2r• sin20-M■ sin( + )
JM2 + r2 - 2M • r ■ sin ( + pm)
Pou = < + arctg-
r•cos(
M - r • sin (< + Pin)
where r — length of pivot lever assembly, mm; 9 — setting angle of pivot lever assembly throughout the longitudinal axis of the tractor, degree.
When selecting the steering linkage parameters necessary to ensure the lowest possible difference between the theoretical (the expression 4) and actual (in the words 5) angles of the steerable
(5)
wheels turning during the whole process of turning until the maximum value turning angle of the internal fi steerable wheel. The
o o I tnmax
proposed method allows to implement such a choice as at the stage of designing tractor as during the verification calculation of existing steel structures of tractors and other self-propelled machines with the same steering mechanisms of turning.
3)
b)
l = -
M
1 - 2 y sin^
Figure 3 — Location of the trapezoid on the tractor; a — front; b — rear The main parameters that determine the kinematics of steering linkage are setting angle f of pivot lever assembly at the neutral position of steerable wheels, distance M between the centers of shaft of the turning pivots and a length r of the pivot lever assembly.
Setting angle of the steering linkage pivot lever assembly (Fig. 2 and 3)
y= arcctg ^^, (6)
where / = - = 0,12...0,16, [4, 668-675].
(8) (9)
M
where x — coefficient of proportionality depending on the cross-section point of location of pivot lever assembly extension pivot arms axles with longitudinal axis of the tractor; x=1 cross-section point overlap with the tractor kinematic center.
9 optimum angle value is located in the range x= [0.7-1.0], [4, 668-675].
Length l of the lateral pull of steering linkage: at rear location (Fig. 3, b)
M
(7)
l = -
at the front location (Fig. 3a)
1 + 2 y sin^
As an example let's perform step by step calculation base on proposed methodology of steering linkage for perspective of the cotton growing tractor JSC "Tashkent agricultural techniques producing plant", in the event: L=2560 mm, B=1800 mm, the M=1395 mm, a=93mm, ls=161 mm, rs=460 mm, A+C=890 mm, r=7°, 8=4°, B =55°, mounted tires 11,2R20, agrotechnical clear-
/ ' ' r inmax ' ' ' <D
ance of 825 mm, a trapeze will be located behind the front axle beam.
1. In terms of (1) if M/L=0,545 let's build up theoretical dependency Bou=f (Bn) (Fig. 4).
2. According to terms (4) and (5) for different values of x let's build up a family of curves Bou=f (fiin) corresponding to x = 0.7; 0.8; 0.9; 1.0 (Fig. 4).
40
ßout.,
degree
30
20
0,9 m
0,8 0,7
10
20
30
Figure 4 — Dependence ßou=f (ß^ ^ min (8) for the
40
J-
50 60
ßin., degree
3. Base on the criterion max \ßou — ß*
Kß„ <ßm mgx "" ""
largest value of the turning angle of internal wheel ßn =55° on the family of curves in Fig. 4, let's find the optimal value of quantity x = 0,922, and base on formula (6) — the optimum angle value will be 9= 16°28'.
The optimum value of x is found out by applying the Microsoft Excel software by using "Search solution" function.
4. Assuming the value of y = 0,14 base on the formula (6) let's find the cross tie rod length l=1292,5mm, and from the condition r=(0,12-0,16) l — length of pivot lever assembly r=155-207 mm.
References:
1. OST 23150-80. Wheeled tractors. Fluid power drive of steering system. Technical requirements. - Moscow: NATI printing house. - P. 8.
2. Barskiy I.B. Designing and calculation of tractors. - Moscow: Machinery, - 1980. - P. 222-226.
3. Anilovich V.A., Vodolazhchenko YU.T. Designing and calculation of agricultural tractor. - Moscow: Machinery, - 1976. - P. 408-412.
4. Sharipov V.M. Designing and calculation of tractors. - Moscow: Machinery, - 2009. - P. 668-675.
DOI: http://dx.doi.org/10.20534/ESR-16-11.12-134-136
Toshev Sherzod Ergashevich, Tashkent state technical university the senior research associate — the competitor Pirmatov Nurali Berdiyorovich, Tashkent state technical university, Doctor of the technical sciences, professor, department of "Electric machines" Haydarov Safar Djovlievich, Tashkent state technical university, Ph. D., associate professor, department «Electric stations, network and systems»
Duvlonov Jaloliddin Ne'matulla o'g'li, Tashkent state technical university, assistent, department of «<Electric machines» Yakubova Dilifuza Kuanyshovna, Tashkent state technical university, assistent, department of «<Electric machines» E-mail: tshn020785@gmail.com
Analysis of magnetic field in the air gap not expressly pole synchronous generator excitation biaxially at asymmetrical short circuit
Abstract: This article on the developed mathematical model based on the equations of the Park — Gorev considered magnetic field analysis of questions in the air gap is not salient pole synchronous generator with a two-axle drive with asymmetric short circuits.
Keywords: magnetic field, the air gap is not salient-pole synchronous generator, longitudinal — transverse field winding.
The most common accident in electric power systems is a sudden short-circuit on the transmission lines on the tires on the generator station or the terminals, the advent of highly dangerous high currents and other mode parameters [1-3]. The occurrence of electromagnetic transients in electrical systems is largely determined by the behavior of its members and the nature of the process in rotating machines and their design features.
In general, asymmetric modes of the machine — regardless of the choice of the variables that characterize the occurrence of electromagnetic transition process, describing its differential equations will contain periodic coefficients.
To study the electromagnetic processes used traditional schemes "biaxial generator excitation — line — the infinite power of tires", and for this power equation used Park — Gorev takes into account the presence of a transverse field winding [4; 5].
It is known that the analysis of the influence of the magnetic field in the air gap neyavnopolyusnogo biaxial synchronous generator excitation with asymmetric short circuits performed using a mathematical model based on the complete equation Park — Gorev. Given the method of calculation of the magnetic field in the air gap is not salient pole synchronous generator with a two-axle drive with asymmetric short-circuit at the terminals of the generator and the busbar station.
It should be noted that the change in the magnetic field from the perspective of the impact of the displacement of large and small axes of the ellipse shape of the magnetic field in the electromagnetic processes in generators biaxial excitation, which is taken into account through the flux linkage. Here the main influence on the configuration ofthe field excitation currents have transverse rotor winding [5].
For unbalanced short circuit in the electrical system of differential equations of its elements of synchronous generators and generators biaxial excitation describing electromagnetic processes in them, there are periodic coefficients that are a function of time.
Electromagnetic influence of transients in the shorted circuit in the parametric oscillation circuit free phase takes the form of an external disturbance in nature representing elektrodvuzhischeysya forces is a complex periodic function of time, containing an infinite number of odd and even harmonic components. The intensity of the even harmonics shift depends on the angle between the pole axis and the short axis at the time ofwinding asymmetrical short circuit, and its maximum possible value depends on the difference between the longitudinal and transverse responses machine (X'd - X'q ), which acts as the mutual amplitude ratio between the short-circuited and the free phase.
Nature increasing the stator leakage flux associated with the emergence of the free current of the rotor winding to create an ad-
