DESC:FIELD OF THE INVENTION:
This invention relates to the field of agricultural engineering.

Particularly, this invention relates to an agricultural harvesting machine.

BACKGROUND OF THE INVENTION:
Onion (Allium cepa) is the second most important commercial crop of India after potato. In the world, onion crop is grown in about 5.30-million-hectare area with an annual production of 88.48 million tons with a productivity of 16.70 tons per hectare. China stands first in onion production (22.61 million tons from an area of 1.03 million hectares area), in the world, with a productivity of 21.85 tons per hectare followed by India. In India, the onion crop is grown in about 1.20-million-hectare area with an annual production of 19.40 million tons with a productivity of 16.12 tons per hectare. Though China has less land, under cultivation, still, India is lagging in production. The reason behind this is inefficiency of farming practices that suit an average Indian farmer’s pocket and hence they are forced to follow the same age-old traditional farming methods which lead to poor productivity.

Majority of onion farmers, in India, are small scale farmers with limited land allotted to onion farming. For onion plantation, they follow the traditional ‘vaafe’ i.e., ‘flat-bed’ method or ‘multi row raised bed’ method i.e., ‘bed – furrow – bed’ method. This is because, in these methods, onion crops are very closely spaced and, hence, it increases yield. The ‘vaafe’ method has an unorganized crop pattern whereas a bed furrow bed method is an organized method with relatively better yield and also better water efficiency. Hence, lately, farmers can be seen shifting from traditional ‘vaafe’ method to the bed furrow method.

Hence it can be seen that Indian farmers prefer dense plantation methods.

In such dense plantations in India, the most common method used for harvesting is the manual hand-picking method.

The hand-picking method is a better method to ensure zero damage to the onion bulbs while harvesting. But, it is the most time-consuming method and requires a large number of labourers and man hours. Other ways, that involve use of machines, are use of digging type harvesters or onion pulling type harvesters. The digging type conventional harvesters are suitable for dense crop patterns and also provide speedy harvesting of the crop but in this case, there are major chances of damage to onion bulbs. Also, operating costs and power consumption is high in these cases. Existing pulling type harvesters require widely spaced onion rows. This widely spaced crop pattern is not preferred by Indian farmers as this reduces yield. Also, these mechanisms have a complex structure and components which make them less frugal and also require high maintenance.

Therefore, there is a need for a reliable and frugal solution for onion harvesting.

OBJECTS OF THE INVENTION:
An object of the invention is to encourage Indian farmers to practice raised bed plantation as this plantation has proved to increase yield and water productivity.

Another object of the invention is to reliable and frugal solution for onion harvesting.

Yet another object of the invention is to eliminate problems faced in prior art designs, these problems being damage to bulbs, inability to adapt to dense cropping patterns, complexity, cost, and comparatively lower efficiency. Further, this harvesting mechanism can be used either as an attachment to the tractor or can be self-propelled as required.

SUMMARY
According to this invention, there is provided an agricultural harvesting machine, configured to be driven by a vehicle, said machine comprising:
- a soil loosening system, with digging blades, configured to loosen soil around a bulb, said digging blades being provided at a distal end of said soil loosening system, said distal end being an end in communication with a ground having bulbs to be removed from said ground;
- a guiding system, with guide blades, configured to guide leaves to a respective conveying system in order to ensure that adjacent leaves do not entangle with each other and are properly grabbed between belts;
- said conveying system, being inclined with respect to ground, said conveying system, being inclined upwards from a picking point to a dropping point, said conveying system being configured with:
• a belt and pulley system with one end of said belt in communication with said soil loosening system’s digger blades, at a picking point and another end of said belt in communication with a windrowing system at a dropping point, said belt/s being configured to convey a bulb from said picking point to said dropping point;
• driven pulleys being provided at a front of, and nearest to, ground where bulbs are sown; and
- said windrowing system configured to provide an organized exit of onions back to the field for drying, said windrowing system configured, as a collecting container, in an operative downward manner from said dropping point.

In at least an embodiment, said conveying system, said guide blades, and said digger blades are relatively positioned with respect to each other such that
- adjustable distance between guide blades and conveyor ranges from 0.5g to 6; and
- adjustable distance between guide blades and conveyor is less than or equal to distance between guide blades and digger blades.

In at least an embodiment, rake angle of digging blades of said digging system is in the range of 17 degrees to 25 degrees.

In at least an embodiment, said digging blade’s geometry is triangular shaped geometry with its slanted edges causing scouring.

In at least an embodiment, angle of said guide blade’s is in the range of 25 degrees to 35 degrees.

In at least an embodiment, said guide blade’s geometry is selected from a group consisting of semicircular-shaped cross-section geometry, parabola-shaped cross-section geometry.

In at least an embodiment, said belt-pulley system, of said conveying system, comprises two adjacent belts, said belts traveling in a direction opposite to direction of movement of said vehicle.

In at least an embodiment, said belt-pulley system, of said conveying system, comprises two adjacent belts, one belt angularly displacing in a direction opposite to another belt.

In at least an embodiment, said conveying system comprises three shafts, at different locations, said shafts being:
- a master driving shaft at which input torque is applied which is transmitted to said conveyor assembly through said belt and pulley system;
- a grooved idler pulley shaft, hosting grooved idler pulleys, provided at said picking point of said conveying assembly configured to endure bending moment generated due to crushing of leaves for the purpose of griping of dug out bulbs; and
- one or more idler shafts, hosting idler pulleys, incorporated at locations, other than picking point, in said conveying system, configured to maintain required compressive force on leaves of said bulbs.

In at least an embodiment, said conveying system comprises three different pulley assemblies, said pulley assemblies being:
- a driven pulley assembly consisting of a mounting plate that holds said assembly on a frame, a bearing casing, double row angular contact ball bearing, internal circlip to keep said bearing positioned inside said casing, external circlip to position said shaft, driven pulley, key between said shaft and said pulley and fasteners to hold said pulley in place;
- a driving pulley assembly consisting of a mounting plate that holds said assembly on a frame, a bearing casing, double row angular contact ball bearing, internal circlip to keep said bearing positioned inside said casing, external circlip to position said shaft, driving pulley, key between said shaft and said pulley and fasteners to hold said pulley in place, said shaft being extended with a splined portion to bear a gear that drives said driven pulley assembly; and
- an idler assembly configured to loose pulleys to support said belt and prevent excessive belt sag, said idler assembly comprising bushes that serve as sliding static bearings, said bushes being positioned between an outer diameter of a fixed shaft and an inner diameter of a moving pulley.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
The invention will now be described in relation to the accompanying drawings, in which:
FIGURE 1 shows an onion bulb with its polar diameter and its equatorial diameter;
FIGURE 2 shows a typical field layout and crop pattern for the use of the machine of this invention;
FIGURE 3 shows a typical field layout and crop pattern in Row-to-Row spacing;
FIGURE 4 shows a typical field layout and crop pattern in Plant-to-Plant spacing;
FIGURE 5 illustrates a side view representation of the machine of this invention;
FIGURE 6 illustrates a top view representation of the machine of this invention;
FIGURE 7 illustrates an isometric view of a complete rendered mechanism of this invention;
FIGURE 8 illustrates a top view of a complete rendered mechanism of this invention;
FIGURE 9a illustrates the guiding system, the digging system, and the conveying system; of this invention;
FIGURE 9b illustrates the relative positioning of blades;
Figure 10 illustrates manual technique employed for manual harvesting of onions;
FIGURE 11 illustrates a digging blade, designed for the machine, of this invention;
FIGURE 12 illustrates an entire digging system, of the machine, of this invention;
FIGURE 13 illustrates various features of the digging system, of the machine, of this invention;
FIGURE 14 illustrates a CAE stress analysis, of the digger blade, and the digger system, used by the machine of this invention;
FIGURE 15 illustrates a deformation analysis, of the digger blade, and the digger system, used by the machine of this invention;
FIGURE 16 illustrates a FOS analysis, of the digger blade, and the digger system, used by the machine of this invention;
FIGURE 18 illustrates a conveying system, used by the machine of this invention
FIGURE 18 illustrates setup for determining vertical lifting force;
FIGURE 19 illustrates an exploded view of pulley assemblies of the conveyor mechanism;
FIGURE 20 illustrates types of onion leaves at harvesting stage.
FIGURE 21a illustrates top view of a field;
FIGURE 21b illustrates front view of a field;
FIGURE 22A and FIGURE 22B illustrates possible geometries for the guiding blades;
FIGURE 23a and FIGURE 23b illustrate rendered Images of Guiding System;
FIGURE 24 illustrates final prototype; and
FIGURE 25 illustrates final mechanism on a vehicle.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
According to this invention, there is provided an agricultural harvesting machine.

For the purposes of this invention, the inventors studied three popular onion varieties in India viz., Satara Garva, Arka Kalyan, and Bangalore rose onion. Twenty onion bulbs were randomly selected from the lot of three varieties and their linear dimensions such as polar diameter and equatorial diameter were measured. Vernier caliper was used for the measurement of linear dimensions. Polar diameter is the distance between the onion crown and the point of root attachment to the onion bulb. The equatorial diameter is the largest diameter perpendicular to the polar diameter.

FIGURE 1 shows an onion bulb with its polar diameter and its equatorial diameter.

The following was observed:
Polar diameter: The maximum bulb polar diameter was observed with Satara Garva (47.23 ± 5.34 mm) and the minimum in Bangalore Rose onion (29.07 ± 3.31 mm). The bulb polar diameter of Arka Kalyan was 43.48 ± 4.21 mm.

Equatorial diameter: The maximum bulb equatorial diameter was observed with Satara Garva (54.54 ± 5.30 mm) and the minimum was observed in Bangalore Rose onion (28.88 ± 3.15 mm). The equatorial diameter of Arka Kalyan was 45.38 ± 3.77 mm.

Unit mass of onion: One hundred onion bulbs drawn randomly from each variety were weighed individually using an electronic balance having the least count of 0.1 g. The mean bulb mass of each variety was computed and reported as unit mass. The maximum mean unit mass of the bulb was observed with Satara Garva (66.16 ± 18.33 g) followed by Arka Kalayn (39.79 ± 8.56 g) and Bangalore Rose onion (10.28 ± 2.74 g).

For the tested 3 onion genotypes,
Onion bulb weight: 10.28 ± 2.74 to 66.16±18.33 g
Polar diameter: 29.07 ± 3.31 mm to 47.23 ± 5.34 mm
Equatorial diameter: 28.88 ± 3.15 to 54.54 ± 5.30 mm

The height of the onion crop during harvesting is 30-60 cm- partially lodged from the neck of the onion bulb. and crop stem diameter is 1-2 cm. The depth of an onion bulb depends on onion variety, soil type, and soil condition. The depth of onion below the ground is about 3.5 to 7 cm.

The compressive strength of stem of seedlings was 30 to 35 N for stem respectively during harvesting period. Khura et al. (2010) found that the mean value of maximum crushing force required for the onion bulb increased by 30% with the change in size from small to medium and 25% from medium to large size bulbs. The same followed for the onion stem. The compressive strength values are useful in deciding the optimum holding force.

From these physical properties, it is desired to design a digger blade that should not damage the onions during digging and should be able to dig and lift the onion from the soil. Also, these properties help in the proper operation of conveying system.

For the purposes of this invention, the inventors studied onion field layout and crop pattern.

Field dimensions are considered to achieve proper spacing and population density, suitability for drip and sprinkler irrigation, cultivation practice, etc. Improper selection of these parameters produces an overuse of water and loss in crop production. In mechanized farming, mechanical equipment will result in less work if a standard width between the furrows is maintained. This way the spacing of the tool attachment does not need to be changed when the equipment is moved from one crop to another.

FIGURE 2 shows a typical field layout and crop pattern for the use of the machine of this invention.

In a preferred embodiment, each bed should be 0.75m wide separated by a 0.375m wide-furrow from an adjacent bed. Preferably, furrow bed height should be 0.15 m.

FIGURE 3 shows a typical field layout and crop pattern in Row-to-Row spacing.

FIGURE 4 shows a typical field layout and crop pattern in Plant-to-Plant spacing

Based on the study for best results this pattern should be implemented. There is a considerable effect of plant density (intra-row spacing) on yield.

The root depth and its spreading pattern of onion plants were considered in the development of the onion harvester.

Onions have to be planted in 5 rows which are 0.15m apart. Looking to local growing practices and the recommendation of agronomists, it was decided to keep the row to row spacing of 0.15 m.

An onion will be planted 0.10 m apart in each row. (Plant to plant spacing)

According to prior art, many attempts were made to design machines for onion harvesting rather than conventional hand picking. One of the major problems faced by such machines was the inability to adapt to dense Indian cropping patterns, design complexity, higher initial as well as operating costs. Also, considerable damage is caused to onion bulbs by these prior art designs which are undesirable as slight damage to an onion bulb may lead to its wastage.

In at least an embodiment, this invention comprising the following sub-systems:
1) Guiding system;
2) Digging / Soil loosening system;
3) Conveying / picking system.

FIGURE 5 illustrates a side view representation of the machine of this invention.

FIGURE 6 illustrates a top view representation of the machine of this invention.

In at least an embodiment, an onion stem is grabbed at a picking point of the conveying system, of the machine, of this invention, and pulled out. The conveying system is essentially a belt-pulley system that is continuously operating and the onions are gripped between two adjacent rubber belts. The belt travels in direction opposite to that of the vehicle which comprises the machine. As the vehicle moves forward, the onion stem is gradually grabbed at the picking point and conveyed to a dropping point. According to the field layout, there are 5 rows of onions. Hence, the machine, and vehicle, has to pull out 5 onions simultaneously. For this, 5 pairs of conveyors are provided as shown in the Figure 6, Figure 7, Figure 8, and Figure 9. Height of picking can be varied and is generally kept between 15mm to 35mm above its bulb where the stem is strongest and necking does not happen at this point.

The efforts required to lift the onions are reduced by a soil loosening system. In at least an embodiment, the soil loosening system loosens soil around an onion bulb and pushes it above the soil, reducing force required to pull the onion from the soild.

In actual cases, the field layout and crop pattern might deviate slightly. Hence, guiding blades ensure that adjacent onion leaves do not entangle with each other and are properly grabbed between the belts.

In at least an embodiment, a windrowing system provides an organized exit of onions back to the field for drying or to storage boxes as required.

FIGURE 5 explains the forces acting on an onion to lift it. As shown, the belt exerts a force at an angle with the onion. The vertical component of this force lifts the onion.

Thus, the picking mechanism, the soil loosening system, the guiding system, and the windrowing system; all work in coordination to efficiently harvest the onions.

FIGURE 7 illustrates an isometric view of a complete rendered mechanism of this invention.

FIGURE 8 illustrates a top view of a complete rendered mechanism of this invention.

FIGURE 9a illustrates the guiding system, the digging system, and the conveying system; of this invention.

It is to be noted that relative positions of the picking / conveying system, the guiding system, and the digging system are important. During harvesting, onion leaves must first be guided to a respective conveying system using guide blades. Simultaneously, digging blades should loosen the soil. And, then, onion bulbs can be efficiently pulled out using the belt- pulley system.

FIGURE 9b illustrates the relative positioning of blades.
Here,
g = length of guide blades (12)
d1 = distance between guide blades (12) and conveyor
d2 – distance between guide blades (12) and digger blades (14)
Thus, for an efficient transition from one system to another, d1 and d2 range from 0.5g to g and, also, d1 <= d2.
The dimensions d1 and d2 may be adjustable in the system and must be set before the start of the harvesting process depending on crop that is to be harvested, its dimensions, and soil conditions.

The flow of onion into the harvester system follows the path in the order – guide, digging, and, finally, picking

Onions / bulbs entering the harvester, may or may not be aligned with the harvester axis. Hence for efficient picking, the onion leaves would first be guided by the guide blades to ensure proper gripping of the leaves at the picking point.

In between guiding and picking up the onions, the digging blades ensure that the soil underneath the onion bulb is properly loosened. Thereby reducing the efforts required by the picking system to lift the onion from the ground.

So, the positioning of the three said systems need to be done such that once the onion leaves are guided into the system by the guide blades, the digging blades should come into action and start loosening the soil beneath the onion bulb. As the digging starts, at the same time the picking mechanism should gradually start gripping and lifting the onion bulb.

If there is a lag between the digging and picking, it could affect the performance as follows. If the digging starts but the onion leaves are not gripped by the picker, the onion may fall on the ground before being picked up. On the other hand, if the picking starts but the digging is delayed, then large efforts would be required to lift the onions which may break the onion leaves and thus again affect the performance. Hence positioning of these 3 systems is critical and would vary from crop to crop.

In at least an embodiment of this invention, there is provided a digging system. Since onion bulbs are normally formed at the soil surface, it is sometimes possible in sandy soils to pull the mature bulbs directly by hand. Where conditions make hand pulling impossible, the crop is harvested by loosening the bulbs before lifting them.

Figure 10 illustrates manual technique employed for manual harvesting of onions.

Manual harvesting of onions is done using Khurpa or spade which is a labor-intensive and time-consuming operation. In our mechanism, the digging system replaces this labor- intensive task.

Therefore, there is a need to loosen soil with maximum digging efficiency without damaging an onion bulb and to provide sufficient lift to the onion bulb. A cutting blade should be replaceable on the machine and to be fastened using an appropriate fastener for ease of serviceability and replacement. Also, design parts need to be multifunctional.

In at least a non-limiting exemplary embodiment, onions will be planted in 5 rows on each bed at 0.15m apart. The approximate size of the onion will be 3 to 6.5 cm. The average depth of onion below the ground is about 3.5 to 7 cm.

Therefore, the digging system, for this invention, to provide flexibility to adjust the cutting depth is up to 100 mm. The rake angle, if less than 17°, will not disturb the soil sufficiently and an angle greater than 25° will tend to collect soil in front of the blade, unnecessarily increasing draft. The rake angle for 100mm cutting depth is maximum and selected as 25 deg. Cutting depth is the function of the rake angle. In normal operating conditions, i.e. for the cutting depth of 80mm, the rake angle is found to be 20.5 deg, keeping the cutting width constant. The material selected as soil cutting blade is spring steel which possesses superior properties and meets the specification of material per IS 2062.

FIGURE 11 illustrates a digging blade, designed for the machine, of this invention.

The performance of a soil working tool depends upon its shape, orientation during movement, and initial soil conditions. As onions will be planted in 5 rows on each bed at 0.15m apart, digging the entire width of the furrow bed (i.e., 75 cm) will result in unnecessary power loss and will make the digging system bulky. Therefore, five digger blades are selected to dig five rows. Taking the onion bulb diameter into consideration, the cutting width of each blade is selected as 9 cm. The cutting width varies with the rake angle and vice versa. But provisions can be made so that it remains constant. The depth of operation should be such that it could dig all the onion bulbs from the soil mass without losing any bulb as buried or damaged. Considering the depth of onion bulbs below the ground, the most probable depth of operation was selected as 8 cm for harvesting without damage to the onion. It can be easily varied depending upon the conditions. To achieve a required cutting depth, if the rake angle increases, the required length of the blade decreases. For extreme operating conditions (i.e., for 100mm depth), if the rake angle is kept maximum (i.e., 25 deg), then, the required length will be minimum. Thus, the length of the cutting blade inside the soil is found out to be approximately 235 mm. Some extra length is provided for the bolting of the blade where the thickness is maximum and has adequate strength.

In at least an embodiment, the digging blade’s geometry is triangular and is designed so that the slanted edges cause soil scouring. The blade is designed for its thickness based on load acting on it by FEA.

Table 1, below, describes a non-limiting exemplary embodiment, of the digging blade, used in this invention.

Parameter Value
Geometry of blade Triangular
No. of blades 5
Required blade length inside the soil 230 mm
Overall blade length 270 mm
Thickness of blade inside the soil 13 mm
Thickness of blade for bolting 18 mm
Cutting width 90 mm
Overall width 140 mm
Table 1

Draft force depends upon sharpness of cutting edge, working speed, working width, working depth, type of implement, soil condition.

The draft force of a soil working tool is directly proportional to the tool width and increases exponentially with operating depth (Grisso et al., 1980; Godwin and Spoor 1977).

Soil types: This is the most important factor affecting the draft force. When the moisture content increases, the draft will be increased up to the plasticity range, in sandy soil the draft increases and in clay soil, the draft decreases. A dry soil requires excessive power and also accelerates the wear of cutting edges. In fine soil texture, the draft is high, but in coarse-textured soils, the draft is low.

Tillage depth: Depth of operation is directly proportional to the draft.

Forward speed: Speed is directly proportional to the draft, when the speed increases the draft also increases. From the previous studies, it was revealed that draft force is less affected by the forward speed at lower speeds but is much affected by depth.

As the blade was moved through the soil, the soil was disturbed as it was cut and thrown to the sides of the tool. The soil disturbance generated was observed, assessed, and analyzed. With increasing the forward speed, working depth, and blade width, the draft force, energy requirement, and soil disturbance significantly increased.

The results showed that draft forces increased significantly for all tools when operating depth was increased. An increase in the draft is due to a greater depth of penetration, larger surface area, and more soil resistance which requires more force to break up the soil. The reason for increased draft force for all tools with an increase of tillage depth and forward speed level is the high acceleration to the soil particles during their displacement.

Draft force is calculated by,
Draft force = soil resistance (Kg/cm²) x cross- sectional area of furrow.

Soil resistance is different for different soils and is the result of cohesive forces between individual soil particles and frictional resistance met by particles that are forced to slide over one another or to ride out of interlocking positions to make way for growing roots. The depth of soil, internal friction angle, and cohesion coefficient was found to be directly related to the cutting resistance of the soil. Black soils are one of the most fertile soils and are widely used for onion production.

As the worst-case scenario for the design, Resistance of soil = 0.7 Kg/cm². For triangular blades,
Furrow Area= (cutting width of blade x cutting depth)/2
= (9 x 8) / 2
= 36 cm²

Draft force= 0.7 x 9.81 x 36= 247.3 N
Total draft force= 247.2 x 5= 1236 N

In at least an embodiment, the digging system, of the machine, of this invention, is designed keeping in mind the following points:
• Provision for Depth adjustment;
• Shear angle adjustment to adjust with the soil type and working conditions;
• Simple in design and easily maintenance;
• Durable and economical operation;
• Flexible and less bulky.

FIGURE 12 illustrates an entire digging system, of the machine, of this invention.

FIGURE 13 illustrates various features of the digging system, of the machine, of this invention.

As revolute joint (the pivot of link no.1) has only one degree of freedom, the system can be structured by restricting the Degree of Freedom. Here, link no.2 is restricting the freedom of link no.1. By proper selection of material for links (i.e., mild steel) and FEA, the system is made stiff with a minimum no. of components.

Based on maximum shear stress theory, applying the criteria of eccentric loading perpendicular to the axis of bolts, the size of the Allen cap bolt is selected as M10. The supporting member for bolting of blades is manufactured by Hot Rolled MS of 14 mm thickness by cutting process followed by bending. It has no welded components.
Overall width of digging system= 870 mm

FIGURE 14 illustrates a CAE stress analysis, of the digger blade, and the digger system, used by the machine of this invention.
Static structural analysis was performed in ANSYS Workbench.

FIGURE 15 illustrates a deformation analysis, of the digger blade, and the digger system, used by the machine of this invention.

FIGURE 16 illustrates a FOS analysis, of the digger blade, and the digger system, used by the machine of this invention.

On the basis of FEA design, the digger blade, and the digger system, used by the machine of this invention was determined to be safe.

In at least an embodiment of this invention, there is provided a conveying system.

As the soil around the onion bulbs is loosened and the onion is pushed up by the digging system, the onion stem has to be gripped and pulled up to harvest the onions. This gripping and pulling of the onions is done by the belt-pulley system. In at least an embodiment, the position between the digging system and conveying system is so adjusted that as the onion is pushed up by the digging system, it is simultaneously gripped by the belts. If the soil is loose enough and the onions can be pulled out without much effort, then the digging system can even be detached and the onions can be directly pulled out by the conveying system.

There are two main advantages of this type of mechanism over prior art mechanisms:
- the mass entering the conveyor is only the onion mass and not the soil mass; hence, the power that is required to convey the unwanted soil mass is reduced;
- another important advantage is that the onions enter the conveyor in an organized manner and hence if required can be stacked in an organized way and sent to the storage area; hence, the post-harvest processes become very convenient.

In at least an embodiment, the conveying system, of the machine, of this invention, is designed keeping in mind the following points:
• No damage to the onion bulbs
• Efficient and organized collection and delivery of onions
• To have optimum harvesting speed
• To convey onions in aligned manner

In at least an embodiment, the conveying system has been designed keeping in mind crop pattern, field dimensions, and onion properties. The conveying system is inclined with respect to the ground. In a non-limiting exemplary embodiment, the conveying system uses 10 belt-pulley systems. Two adjacent belt-pulley systems form one conveying unit. As the field pattern selected, in the non-limiting exemplary embodiment, discussed above, consists of 5 onion rows, 5 such conveying units are required.

In at least a single conveying unit, two adjacent belts involved in the single conveying unit angularly displace in opposite directions. The onion is grabbed, by its stem, at the picking point as shown in the image. As the onion is gripped between the belts, the continuously operating belts pull out the onion and convey it to the dropping point.

FIGURE 18 illustrates a conveying system, used by the machine of this invention

Due to less space between the onion rows, a compact assembly was required with a long conveying length. Table 2, below, shows conveying system dimensional constraints:
Pulley type Labeled as Diameter
Grooved pulleys Driving Pulley 55 mm
Driven pulley 50 mm
Grooved Idler 45 mm
Flat Pulleys Flat Idler 35 mm
Table 2

Due to small pulley diameters, the primary requirement while selecting a belt was high flexibility to adapt to small diameters. Also, the belt should be broad enough to hold onion leaves with sufficient grip. For this banded cogged belt with XPZ/3VX profile was selected. Following are the features of the XPZ/3VX banded cogged belts:
- The cogged belt is well suited for drives with smaller diameter pulleys.
- It has Less slip and wear.
- They run cooler, last longer, and have an efficiency that is about 2 percent higher than that of standard V-belts.

Table 3, below, shows parameters that are crucial for precise calculations:

Parameters Values
Coeff. of Friction between rubber and aluminum (??) 0.6
Conveyor inclination (?) 30 degrees
Driving pulley Radius (R1) 55 mm
Driven pulley Radius (R2) 50 mm
Distance between the belts (d) 4 mm
Pulley groove angle (2ß) 36 degrees
Optimum Harvesting Speed (vh) 0.7944 m/s
Optimum Belt Speed (vb) 0.8539 m/s
Compression Force (Fc) 60 N
Conveying Length (l) 800 mm
Onion plucking height (h1) 20 mm
Onion Dropping Height (h2) 420.047mm
Distance between Onions (??) 100 mm
No. of onion rows (n) 5
Maximum mass per onion (m) 100 g
Angle turned to compress the onion(O’) 50 degrees
Maximum onion stem diameter (D) 20 mm
Lap angle (O) 200.3 degrees
Table 3

Now, other crucial parameters that are necessary for designing conveying system calculations are:
- Vertical lifting force
- Coefficient of friction between onion stem and rubber belt

These parameters were unknown and were found out using following setups:

FIGURE 18 illustrates setup for determining vertical lifting force.

This is the force required to pull out the onion out of the soil vertically. The vertical force required varies greatly with:
- Soil type
- Age of the onion
- Planting method
- Use of chemicals
- Moisture content
- Sowing depth

Experiments were carried out on 50 random onions at different onion fields and individual force was measured using a setup. The setup used digital spring balance and pulley system to measure the vertical lifting force. The result obtained are shown in the Table 4, below:

Parameters Forces
Maximum 9.97 kg
Minimum 1.57 kg
Mean 5.4 kg
Table 4

Typically, an onion will be gripped between the rubber belts and lifted gradually. Hence the coefficient of friction between the onion stem and the rubber belts is crucial in calculations. To find this unknown parameter, sliding friction apparatus is used. The setup for the same is shown in the image.

Experiments were carried out on onions at 3 different stages:
- 10 days after transplant
- 7 days after cut-off
- 15 days after water cut-off

Results are mentioned in Table 5, below:
Parameters Average Coefficient of Friction
10 days after transplant 1.1935
7 days after cut-off 1.3533
15 days after water cut-off 0.9141
Table 5

Power requirement of the mechanism depends on the conveyor angle, harvesting speed, and belt speed. While designing, iterations were carried out for the conveyor angle, harvesting speed, belt speed, and optimum values of each were set. Care was taken to ensure sufficient reserve power.

Worst cases were considered while designing the mechanism i.e., maximum vertical force, minimum coefficient of friction and thickest onion stem so that the system can work even in the harshest conditions.

Considering 5 onion rows, at a 30-degree conveyor angle, the force required along the conveyor to pull onion is around 231.164N. The total power utilized for the mechanism is 1233.97 Watts and the torque requirement is 34.83N at peak loads.
While harvesting the onions, power is required to perform three actions simultaneously – Lift the onions, compress the onions between the belts and raise the onions in the system by some height.

Force required along the belt to pull out the onion
F = Fv
sin ?
=195.389 N
? Torque required per driven pulley to lift the onions (T1) and to compress the onion stem between two belts (T2) is given by

? Total torque requirement per driving pulley is
T= (T1 + T2) × R1
R2

Corresponding Power,

=3.1837 N-m

Power required per pulley system to lift the onions already hanging in the conveyor belt before next onion is lifted can be written as
P2 = m×g× ??b ×sin (?)/2
=2.0002 Watts
Thus, total power required for mechanism
P = P1 + P2 = 102.6633 Watts
Considering the efficiency of each spur gear pair as 0.98 Total power = 1080.3132 Watts or 1.44872 HP
Total torque to drive the mechanism = 30.3186 N-m

Pulley – belt calculations:

T1 = Tension in the tight side T2 = Tension in the slack side
The torque at the driving pulley can be written as
T = (T1-T2)1
Considering the maximum torque at the last driven row
T =3.52218 N-m

Also,

The required initial tension for transmitting given power and torque
Pulley assembly and conveyor frame design

The conveying mechanism contains 3 different pulley assemblies as shown in the figures. The pulley assemblies are designed for easy and quick assembly and serviceability.

FIGURE 19 illustrates an exploded view of pulley assemblies of the conveyor mechanism.

In at least an embodiment, Assembly 1 (Driven assembly) and Assembly 2 (Driving assembly) are similar to each other. The only difference is that in driving assembly, the shaft is extended with a splined portion to bear a gear that will drive the assembly. Both these assemblies consist of a mounting plate that holds the assembly on the mechanism frame, Casing to hold bearing, Double row angular contact ball bearing, Internal K-type Circlip to keep the bearing positioned inside the casing, Shaft, K-type external circlip to position the shaft, Pulley, Square Key between shaft and pulley and fasteners (M8 washer and nut) to hold the pulley in place. Assembly 3 (Idler assembly) is used for the loose pulleys to support the belt and prevent excessive belt sag. As this assembly is not subjected to the belt tension directly, the radial loads on the bearing that is needed here are very negligible. Hence in this assembly, the bearings are replaced by Delrin bushes that serve as sliding static bearings. This significantly reduces the cost of the assembly. The bush is positioned between the OD of the fixed shaft and the ID of the moving pulley.

In the Conveying system there are 3 shafts at different locations. Dimensions of these shafts vary with the forces acting on them, according to the angle of contact of belt and torque acting on them.

Master Driving Shaft: It is the shaft at which input torque of 3.65 Nm (Max) is applied which is then transmitted to conveyor assembly through belt and pulley system.

Driven Shaft: It is located at the picking point of assembly which endures bending moment generated due to crushing of onion leaves for the purpose of griping it. As there is no torque transmission on this shaft so shear stress will be zero.

Idler Shaft: This shaft is incorporated in the system to maintain the required compressive force on the onion leaf.

Dimensions of the shaft were designed according to the space constraints as assembly had to be as compact as possible and also according to availability of the bearing diameter.

The fluctuating stresses due to bending and torsion are given by

where Mm and Ma are the midrange and alternating bending moments, Tm and Ta are the midrange and alternating torques, and Kf and Kfs are the fatigue stress- concentration factors for bending and torsion, respectively.
s’a = (sa2 + 3t a2)1/2
s’m = (sm2 + 3t m2)1/2

the fatigue failure criteria for the modified Goodman line

To check for yielding, von Mises maximum stress is compared to the yield strength

The bearings are used for driving pulley assembly and the driven pulley assembly. As the bearing experiences moment loads in addition to radial and axial force, double row angular contact ball bearings are used.

In at least an embodiment of this invention, there is provided a guiding system.

FIGURE 20 illustrates types of onion leaves at harvesting stage.
When the bulbs developing from the leaf bases are fully formed, the leafy green tops begin to turn yellow and eventually collapse from a point a little above the top of the bulb, leaving an upright short neck. Due to this, leaves of the adjacent rows may get entangled at the picking point of the mechanism which is unfavorable.

In the Conveying System, driven pulleys are at the forefront and nearest to the ground and so there is always a possibility of damage from surrounding objects. So, the blades are designed such that the leaf is raised up to a certain height which avoids entangling and protects the pulley.

While sowing it is unlikely that bulbs are implanted in an aligned manner. So, with only conveying assembly misaligned onions cannot be picked and so those unpicked onions may block the picking of onions ahead. This has been eliminated by designing the shape of the blade such that it guides those misaligned onions towards the Picking point.

In at least an embodiment, the guiding system, of the machine, of this invention, is designed keeping in mind the following points:
• Lightweight yet robust design
• Leaf has to be raised to the picking point
• Protect the driven pulleys from any damage
• Guide a misaligned onion to the picking point

In ideal case the onions may be planted exactly in the straight line. But in actual case, the pattern may deviate slightly as shown below.

FIGURE 21a illustrates top view of a field

FIGURE 21b illustrates front view of a field

From the top view, it suggests that the guide system should have a V-shape opening to facilitate onion to picking point and width should be less than inter onion distance to avoid any damage to the onion bulb.

Width and Length should be adjusted such that an Onion can slide over the surface of the blade and is not pushed forward.
From the side view, the system should have a gradually increasing structure such that it raises the leaf to a height slightly above the picking point.

In at least an embodiment, FIGURE 22A and FIGURE 22B illustrates possible geometries for the guiding blades:
Semicircular shaped cross-section: This shape does not satisfy the functional requirement of raising the height to obtain the required elevation, width has to be increased which is not feasible as the blade may partially obstruct onion from intake.
Parabola Shaped Cross section: In this design drawbacks of the previous shape are eliminated and also it complies with the requirement.

Height of blade: The blade should raise a leaf to the picking point and should also cover the pulley. Hence, Height >= (maximum height of picking point above ground) + (Height of pulley above picking point)

Maximum height of picking point above ground = 35 mm Height of pulley above picking point = approx. 70 mm

Height >= 35 + 75 Height = 100 mm

Width of blade
Onion passage Gap = 20 mm Width = (150 - Gap) / 2
= (150 - 20) / 2
= 130 mm

Length of Blade
While selecting length of the following points were considered:
a. The guiding blades should be engaged before the onions are completely pushed above the soil by the digging blades. Because if the onions are pushed completely before the guides are engaged, onion may fall on the field and may not be guided to the conveyor. Hence maintaining proper relative position between the guiding and digging system is important.
b. The fallen onion leaves need to be gradually raised. Hence the raising angle should be kept as low as possible.
So, by considering these factors, it was found that 30 degree raise angle provides sufficient guiding to the leaves.

Hence, Length = height / tan (30) Length = Height * 1.732
= 173.2 mm
This was rounded off to 200mm for ease of manufacturing and bending of the parabolic shape. This assumption resulted in a decent Raise Angle of 26.56 deg
Parameters Values
Height 100 mm
Width 130 mm
Length 300 mm
Raise Angle 26.56 deg
Thickness 2 mm
Material MS sheet
Table 6
FIGURE 23a and FIGURE 23b illustrate rendered Images of Guiding System.
FIGURE 24 illustrates final prototype.
FIGURE 25 illustrates final mechanism on a vehicle.

TECHNICAL ADVANTAGES:
- The multirow agricultural harvester can be used for bulbous crops such as onions;
- The current invention is more frugal, efficient and compact as compared to existing designs
- Unlike existing designs, this machine is best suitable for dense crop patterns which is the most practiced plantation pattern by Indian farmers
- Compared to existing designs, the current invention is very simple in design.
- The mechanism is designed for serviceability.
- The mechanism can be used for single row or multiple rows as per requirement
- Self-adjusting conveyor speed for maximum yield
- Special guiding system for organized entry of the onions
- Similar to hand harvesting of onions
- Ensures minimum damage to bulbs
- Can be used as an attachment or can be self-propelled

The harvesting mechanism, of this invention, ensures minimum damage and maximum efficiency. It is divided into four major parts.
1) Guiding system
2) Digging system
3) Conveying system
4) Windrowing system

The Onion stem is grabbed between two rubber belts of the conveying system and lifted. The efforts required to lift the onions is reduced by the soil loosening system. Guiding blades are designed such that the adjacent onion leaves do not entangle and are properly grabbed between the belts. The windrowing system (25) provides an organized exit of the onions back to the field for drying or to the storage boxes as required.

Thus, the picking mechanism, soil loosening system, guiding system and windrowing system work in coordination to efficiently harvest the onions.

Beginning with the first part the digging system or we can call this as the soil loosening system. The main objective of the blades here is just to loosen the soil and push the onions above the soil. If any one of the blades gets damaged, Only the damaged blade can be replaced individually without the need to change the complete digging assembly. Different soil types require different shear angles. Hence provision to adjust the shear angle has been provided to adapt with the working conditions. The depth adjustment provision on the digger is given to vary the depth of digging and also to raise the digger to provide the required ground clearance when the machine is not harvesting.

At maturity stage, the onion leaves are partially fallen from the neck. Also, the crop cultivation pattern might deviate slightly. The onions may not be planted exactly in straight line. The leaves of onions may be falling on one another. For this purpose, a special guiding system is designed that separates and guides the onion leaves coming in its path into respective belt pulley system.

The lowermost pulley of the conveyor was found vulnerable to damage due to impact with the uneven terrain. Hence an extended surface is provided on the guide blades to protect the lowermost pulley.

Thus, digging and guiding systems together assist the mechanism in efficient harvesting of onions.

The most important stage of the harvesting mechanism i.e. the pulling mechanism or the conveyor system. As mentioned earlier our harvester uses a very unique mechanism. In this the onion is seeing an impact as that of hand picking. This ensures minimum damage to the onions.

The cultivation pattern on raised bed method has multiple rows and the number of rows may vary. Accordingly, the number of rows on the harvester can be varied. Typically, the dense Indian plantations on the raised bed have 5 rows. For this, 5 pairs of conveyors are provided as shown in the image. Each pair of conveyors contains belt-pulley system continuously operating. The belt travels in an opposite direction to that of the vehicle. As the vehicle moves forward, the onion stem is gradually grabbed at the picking point at about 20 mm above its bulb where the stem is strongest and is gradually lifted (This height can be varied using the height adjustment provision). The topmost image explains the forces acting on the onion to lift it. As shown, the belt exerts a force at an angle with the onion. The vertical component of this force lifts the onion. The belts grab the onion between them and convey it to the dropping point where they are dropped to the windrowing system and eventually on the ground or storage crates as required.

The windrowing system specifically used on this machine is a simple sheet metal structure as shown in the image that lays back the onions on the fields for curing/drying purpose. In general, the windrowing system could be of various types and complexity levels as per the application. If the application requires the collection of onions, the windrowing system could use a crate/collection container, or if the application requires cutting the leaves, sorting the onions by size, and then collecting in different crates, it could use a further complex windrowing system consisting of these functionalities.

The selection of the belt was done keeping in mind the main application, power requirement and the pulley size. Due to less space between the onion rows, a compact assembly was required with long conveying length. This restricted the sizes of the pulley. Due to the small pulley diameters, the primary requirement while selecting belt was high flexibility to adopt on small diameters. Also, the belt should be broad so as to hold onion leaves with sufficient grip. For this banded cogged belt with XPZ/3VX profile was selected from the belt selection graph.

The position between the digging system and conveying system is so adjusted that as the onion is pushed up by the digging system, it is simultaneously gripped by the belts. If the soil is loose enough and the onions can be pulled out without much efforts then the digging system can even be detached and the onions can be directly pulled out by the conveying system.

The power requirement of the mechanism depends on the conveyor angle, harvesting speed and belt speed. While designing iterations were carried out for the conveyor angle, harvesting speed, belt speed and optimum values of each was set to make best use of the power received from the engine. Care was taken to ensure sufficient reserve power.

Worst cases were considered while designing the mechanism i.e., maximum vertical force, minimum coefficient of friction and thickest onion stem so that the system can work even in the critical conditions

Now moving towards the last part of the mechanism. The windowing system. The onions dropped at the dropping zone are laid back on the field for curing purpose or dropped in the storage crates as per the requirement.

There are two main advantages of this type of mechanism over the conventional mechanism. The mass entering the conveyor is only the onion mass and not the soil mass. Hence the power that is required to convey the unwanted soil mass is reduced. The onions enter the conveyor in an organized manner and hence if required can be stacked in an organized way and sent to the storage area.

The TECHNICAL ADVANCEMENT of this invention lies in providing a mechanism which eliminates the problems faced in existing designs such as damage to the bulbs, inability to adapt to dense cropping patterns, complexity, cost, and delivers comparatively higher efficiency. Further, the harvesting mechanism can be used either as an attachment to the tractor or can be self-propelled as required. The current invention eliminates prior art problems and harvests onions with optimum use of power supplied by a prime mover and obtains maximum fuel efficiency with a high productivity rate. Also, minimum damage or negligible damage to onion bulbs is caused by the use of this invention.

BENEFITS, over prior art:
1. Reduces damage to the onion bulbs to nearly zero and maximizes efficiency
2. 5 times faster than existing designs (up to 40 onions per second with optimum fuel consumption rate at maximum harvesting efficiency)
3. Suitable for small scale as well as large scale farmers
4. Requires less power as compared to other similar capacity harvesters
5. Cheaper than existing models
6. Lower operating cost
7. Can be used for garlic, carrot, radish, groundnut, and other similar crops with little modifications

While this detailed description has disclosed certain specific embodiments for illustrative purposes, various modifications will be apparent to those skilled in the art which do not constitute departures from the spirit and scope of the invention as defined in the following claims, and it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.
,CLAIMS:WE CLAIM,

1. An agricultural harvesting machine, configured to be driven by a vehicle, said machine comprising:
- a soil loosening system, with digging blades (14), configured to loosen soil around a bulb, said digging blades being provided at a distal end of said soil loosening system, said distal end being an end in communication with a ground having bulbs to be removed from said ground;
- a guiding system, with guide blades (12), configured to guide leaves to a respective conveying system in order to ensure that adjacent leaves do not entangle with each other and are properly grabbed between belts;
- said conveying system, being inclined with respect to ground, said conveying system, being inclined upwards from a picking point (12a) to a dropping point (12b), said conveying system being configured with:
• a belt and pulley system (16) with one end of said belt in communication with said soil loosening system’s digger blades (14), at a picking point (12a) and another end of said belt in communication with a windrowing system at a dropping point (12b), said belt/s being configured to convey a bulb from said picking point (12a) to said dropping point (12b);
• driven pulleys being provided at a front of, and nearest to, ground where bulbs are sown; and
- said windrowing system (25) configured to provide an organized exit of onions back to the field for drying, said windrowing system (25) configured, as a collecting container, in an operative downward manner from said dropping point (12b).

2. The machine as claimed in claim 1 wherein, said conveying system, said guide blades (12), and said digger blades (14) are relatively positioned with respect to each other such that
- adjustable distance between guide blades (12) and conveyor ranges from 0.5g to 6; and
- adjustable distance between guide blades (12) and conveyor is less than or equal to distance between guide blades (12) and digger blades (14).

3. The machine as claimed in claim 1 wherein, rake angle of digging blades (14) of said digging system being in the range of 17 degrees to 25 degrees.

4. The machine as claimed in claim 1 wherein, said digging blade’s (14) geometry being triangular shaped geometry with its slanted edges causing scouring.

5. The machine as claimed in claim 1 wherein, angle of said guide blade’s (12) being in the range of 25 degrees to 35 degrees.

6. The machine as claimed in claim 1 wherein, said guide blade’s (12) geometry being selected from a group consisting of semicircular-shaped cross-section geometry, parabola-shaped cross-section geometry.

7. The machine as claimed in claim 1 wherein, said belt-pulley system, of said conveying system, comprising two adjacent belts (17a, 17b), said belts traveling in a direction opposite to direction of movement of said vehicle.

8. The machine as claimed in claim 1 wherein, said belt-pulley system, of said conveying system, comprising two adjacent belts (17a, 17b), one belt (17a) angularly displacing in a direction opposite to another belt (17b).

9. The machine as claimed in claim 1 wherein, said conveying system comprising three shafts, at different locations, said shafts being:
- a master driving shaft (21a) at which input torque is applied which is transmitted to said conveyor assembly through said belt and pulley system;
- a grooved idler pulley shaft (21b), hosting grooved idler pulleys (19.5a), provided at said picking point (12a) of said conveying assembly configured to endure bending moment generated due to crushing of leaves for the purpose of griping of dug out bulbs; and
- one or more idler shafts (21c), hosting idler pulleys (19.5b), incorporated at locations, other than picking point (12a), in said conveying system, configured to maintain required compressive force on leaves of said bulbs.

10. The machine as claimed in claim 1 wherein, said conveying system comprising three different pulley assemblies, said pulley assemblies being:
- a driven pulley assembly (19a) consisting of a mounting plate (19.1) that holds said assembly on a frame (15), a bearing casing (19.2), double row angular contact ball bearing (19.3), internal circlip (19.4) to keep said bearing (19.3) positioned inside said casing (19.2), external circlip to position said shaft, driven pulley (19.5a), key (19.6) between said shaft and said pulley (19.5) and fasteners (19.9) to hold said pulley in place;
- a driving pulley assembly (19b) consisting of a mounting plate (19.1) that holds said assembly on a frame (15), a bearing casing (19.2), double row angular contact ball bearing (19.3), internal circlip (19.4) to keep said bearing (19.3) positioned inside said casing (19.2), external circlip to position said shaft, driving pulley (19.5b), key (19.6) between said shaft and said pulley (19.5) and fasteners (19.9) to hold said pulley in place, said shaft being extended with a splined portion to bear a gear (19.7) that drives said driven pulley assembly (19a); and
- an idler assembly (19c) configured to loose pulleys to support said belt and prevent excessive belt sag, said idler assembly comprising bushes (19.8) that serve as sliding static bearings, said bushes (19.8) being positioned between an outer diameter of a fixed shaft and an inner diameter of a moving pulley (19.5).

Dated this 18th day of August, 2022

CHIRAG TANNA
of INK IDÉE
APPLICANT’S PATENT AGENT
REGN. NO. IN/PA – 1785