RU2138785C1 - Individual objects dosing method and apparatus - Google Patents

Abstract

FIELD: agriculture and other branches of industry. SUBSTANCE: method involves periodically exciting working tool with damped oscillations at average acceleration value exceeding acceleration of gravity by deflecting it from equilibrium state by control pulses, with pulse time interval being equal to working cycle period. Apparatus has flexible working tool with one end rigidly connected to hopper and opposite end provided with chamber of negative feedback with opening of size less than critical size. This end is kinematically connected with drive formed as shaft carrying fingers positioned at predetermined space one relative to another. Upon oscillating of working tool, seeds are delivered piece by piece through dosing opening only during damping oscillation of working tool. EFFECT: improved dosing precision , simplified construction and enhanced reliability in operation. 3 cl, 2 dwg

Description

 The invention relates to methods for precise dosing of piece items and can be used in food, chemical and other industries, as well as in agriculture in sowing devices.

 A known method of dispensing piece items, such as seeds, which consists in the fact that the seeds are exposed to mechanical vibrational vibrations [A.S. 719528, 1980, B.I. N 9].

 The specified method has low productivity and does not ensure uniform seed flow due to the fact that the process of forming the main seed flow is carried out by coordinated summation of two seed flows through a complex, and therefore, inertial pneumomechanical automatic control system.

 There is also known a method of dosing seeds [A.S. 917747, 1982, B.I. N 13], the authors took for the prototype, which consists in the combined exposure to them of the air flow and vibrational vibrations with a frequency whose minimum value is equal to the number of seeds sown per unit time. The disadvantage of this method is the combination in one technological process of vibration and aerodynamic fields, which complicates the dispensing process itself and reduces its reliability.

 To carry out dosing, a device is used that includes a hopper, a seed chamber with a vas deferens, a discrete automatic control system equipped with a high-frequency pneumatic-acoustic generator of mechanical vibrations with a resonator and a working element located along the vas deferens in the form of an elastic element. In this device, to give the working body high-frequency oscillations, it is necessary to have a pneumatic-acoustic generator for generating control pulses, a source of compressed air, which complicates the design and reduces the reliability of its operation. Significant disadvantages include the need to form control pulses of the same frequency with which the working body works.

 Tests of this device showed that due to the forced supply of seeds from the seed chamber with an air stream, they jam between the wall of the vas deferens and the elastic element, which violates the uniformity of sowing.

 The task of the technical solution is to improve the accuracy of dosing, simplify and increase the reliability of the process.

 The problem is solved by the fact that damped oscillations are periodically excited in the elastic working body with an average acceleration greater than the acceleration of gravity by deviating it from the equilibrium state by control pulses, and the time interval for following the latter is equal to the period of the working cycle.

The device includes a seed hopper with a working body located in the lower part, a shutter, an unloading plate and a drive mechanism, one end of the elastic working body is rigidly connected to the hopper, and the opposite end is equipped with a negative feedback chamber with a metering hole, the size of which is less than critical and kinematically connected with drive in the form of a shaft with fingers arranged in increments equal to
l _w = ωR (T _o / n),
where ω is the circular frequency of the drive shaft, 1 / s; R is the length of the fingers, m; n is the number of fingers, pcs; T _about - the period of rotation of the shaft, C.

The novelty of the proposed proposal lies in the fact that in the elastic working body periodically excite high-frequency damped oscillations, the average acceleration of the oscillations is greater than the acceleration of gravity, and the time interval following them is equal to the period of the working cycle t _p oscillations. This set of features allows you to get a nest (several grains in the nest) or a dotted (piece) arrangement of seeds in the furrow.

The method is carried out by deviating the working body from a state of equilibrium. By changing the frequency of rotation of the shaft, the number of fingers, the value of their overlap with the working body, you can get any ratio between t _n and t _p .

 The highest performance of the dispenser is achieved if the subsequent deviation of the working body will follow immediately after the end of the time of spontaneous oscillations of the working body. The duration, frequency and amplitude of the oscillations are selected based on agrotechnical requirements.

 In FIG. 1 is a diagram of a dispenser; FIG. 2 - cyclogram of his work.

 A device for implementing the method includes a seed hopper 1, in the lower part of which there is a working body in the form of an elastic plate 2 with a metering hole 3, a discharge plate 4 installed in the hopper 1, a shutter 5, and the working body is kinematically connected with the seeder wheel (in Fig. Not indicated) through the drive mechanism 6 in the form of a shaft with fingers 7.

 The working body 2 relative to the bottom of the hopper 1 is mounted with the possibility of movement in the vertical direction and is equipped with a negative feedback chamber 8. The metering hole 3 (one or several) located in this chamber has a sectional area less than critical, which allows organizing piece-wise outflow of seeds through it.

The critical area is the smallest hole area over which a stable arch is formed in statics, for example for a round hole
D _cr = (5 ... 7) d _e ,
where D _cr - the critical diameter, m; d _e - equivalent body diameter, m; for example, the geometric mean size (see Katalymov A.V., Lyubartovich V.A. Dosing of bulk and viscous materials. - P .: Chemistry, 1990).

The metering hole 3 has a diameter D = (1.2 ... 1.5) d _e , which allows to resolve a technical contradiction, which consists in the fact that with gravitational flow through the hole only multi-row movement is possible, when a vibration field is applied to the working body the size of this hole will be reduced to the size of the body.

 The working body is made of an elastic material, for example, a steel plate, one end of which is rigidly connected by the hopper, and the free end relative to the finger 7 is installed with overlap. In idle mode, the metering hole is self-locking by seeds.

The workflow is as follows. From the seeder drive wheel, rotation is transmitted to the drive mechanism b, which acts as a seed rate setter, finger 7 deflects up (down) the free end of the working body 2. After the finger 7 disengages under the action of a linear restoring elastic force, the working body begins to oscillate with a high frequency, which decay over time t _p (Fig. 2). Then the cycle repeats. The material properties of the elastic element, the angle of its deviation from the equilibrium position affect the decay time of the vibrations that are organized in accordance with Hooke's law.

From the cyclogram of the work (Fig. 2) it follows that the interval following the control pulses is equal to the period T of the working cycle
T = t _n + t _p
where t _n is the time of deviation of the working body, s; t _p is the time of its oscillations, s.

Step l _W finger placement is selected from the condition
l _w = ωR (T _o / n),
where ω is the circular frequency of the drive shaft, 1 / s; R is the length of the fingers, m; n is the number of fingers, pcs; T _about - the period of rotation of the shaft, C.

где A - амплитуда колебаний, м; g - ускорение свободного падения, м/с².The product ωR is the peripheral speed of the fingers, and the quotient T _о / n is the time the finger rotates through an angle of 2π / n.
The seed dosing process is carried out only on a time interval t _p fluctuations of the working body, while the seeds change their rheological properties (friction coefficient, etc.) and go into a vibrated state and expire through the hole according to the laws of pseudo-fluid. Such a transition is possible if the coefficient of vibration mode G is

where A is the oscillation amplitude, m; g - acceleration of gravity, m / s ² .

 As seeds accumulate in the negative feedback chamber 8, counterpressure increases and the seed supply from the hopper decreases, thereby ensuring a constant seed level above the metering opening. Flaps 4 and 5 adjust the dispenser.

 Such a technical solution allows one to obtain high-frequency oscillations of the working body at a low frequency of control pulses and use this principle, for example, in sowing devices in breeding, summer cottages, in greenhouses, etc., where the use of energy sources (compressor, battery) is impractical, but sufficient the simplest manual drive. The manufactured manual dispensers showed positive results when sowing small-seeded crops (radishes, carrots, onions, etc.).

Claims (2)

 1. A method of dispensing piece goods, for example seeds of agricultural crops, by applying high-frequency oscillations to an elastic working body, characterized in that damped oscillations are periodically excited in the elastic working body with an acceleration greater than the acceleration of gravity by deflecting it from the equilibrium state by control pulses, and this is temporary the interval following the latter is equal to the period of the working cycle. 2. A device for dispensing piece items, including a seed hopper with an elastic working body located at the bottom, a shutter, a discharge plate and a drive mechanism, characterized in that one end of the flexible working body is rigidly connected to the hopper, and the opposite end is equipped with a negative feedback chamber with a metering hole, the size of which is less than critical, and kinematically connected with the drive in the form of a shaft with fingers located in increments equal to
l = ωR (T _o / n),
where ω is the circular frequency of the drive shaft, 1 / s;
R is the length of the fingers, m;
n is the number of fingers, pcs;
T _about - the period of rotation of the shaft, C.

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