Claims:WE CLAIM:
1. A system (100) for draft load control of an implement mounted on a work vehicle, comprising:
a bell crank (110) pivotally mounted on a sensing assembly (10), the bell crank (110) having plurality of slots (112) configured for receiving a top link connected with the implement;
a feedback link (120) having a first end (120a) and a second end (120b), the first end (120a) of the feedback link (120) being connected to the bell crank (110);
a feedback rocker (130) pivotally mounted on body of the vehicle, the feedback rocker (130) having plurality of slots (132), the second end (120b) of the feedback link (120) selectively adapted to one of the slots (132), the feedback rocker (130) movable about its pivot point depending upon force experienced by the implement, and ratio of movement of feedback rocker (130) depends upon the slot to which the feedback link (120) is adapted; and
a linkage assembly (140) interconnecting a control valve (150) with the feedback rocker (130), the control valve (150) responsive to draft control requirement set and movement of the feedback rocker (130) to lift and lower the implement.

2. The system (100) as claimed in claim 1, wherein the feedback rocker (130) comprises plurality of slots (132) positioned in a vertical configuration.

3. The system (100) as claimed in claim 1, further comprising a draft control lever (160) operated by a user for setting desired limits on draft of the implement.

4. The system (100) as claimed in claim 1, further comprising an actuating link (162) connected to the draft control lever (160) and positioned between the linkage assembly (140) and the control valve (150), for controlling the opening of the control valve (150) based on position of the draft control lever (160).

5. The system (100) as claimed in claim 1, wherein the control valve (150) comprises a hydraulic control valve having a spool housed inside a cylinder such that pivotal movement of the feedback rocker (130) causes the spool to move inside the cylinder, thereby controlling the implement.
, Description:FIELD OF THE INVENTION
[001] The present invention relates to a system for draft load control of an implement mounted on rear-side of a work vehicle.

BACKGROUND OF THE INVENTION
[002] Work vehicles such as a tractor have various implements like tiller, seeding implement etc. for carrying out field operations. Depending upon type of field operation and contour/type of field or soil condition, the implement must be suitably controlled to perform the required field operation. The implements are connected to the tractor by means of a three-point hitch system, and the hitch system can be operated to raise and lower the implement. The hitch system is typically hydraulically driven and provides position control and/or draft load control. The position control maintains the implement at a constant working depth whereas draft control raises and lowers the hitch so that force experienced by the implement and thereby the hitch remains constant.
[003] Without a system for draft control, if the implement hits a hard piece of ground, it may lead to wheel slippage and damage to the implement. These systems for draft control sense any extra strain on the implement and allow for the implement to be raised just enough to pass the hard patch of the ground and then return to desired depth set by the user.
[004] As the soil type and requirements for different farming operations like ploughing, transportation, load lifting and lowering change, the requirements of the system for draft control change too. For instance, a seeding application requires the implement to be controlled in a highly precise manner as opposed to a ploughing operation which does not require the implement to be controlled in such a high precision manner. Further, for instance, a softer soil, in which the work vehicle implement can move to a greater depth, will require the implement to be controlled at a higher precision as compared to a harder soil in which the work vehicle and the implement cannot move to such a large depth.
[005] To provide various modes of sensitivity in conventional systems for draft control, the top link is connected to the system of draft control at a bell crank which generally has an upper slot and a lower slot for receiving the top link. When the top link is connected to the upper slot, the system for draft control senses the movement of the implement at a lower sensitivity and is appropriate for a harder soil. A different type of medium soil would require a level of sensitivity which is not as high or low to function in an optimum manner. However, the conventional systems with only two modes of sensitivity limit the functioning of the system and cannot ensure that the work vehicle performs at the same potential in each soil type and varying geographic conditions.
[006] Thus, there is a need in the art for a system for a work vehicle which addresses at least the aforementioned problems.

SUMMARY OF THE INVENTION
[007] In one aspect, the present invention related to a system for draft load control of an implement mounted on rear-side of a work vehicle. The system has a bell crank that is pivotally mounted on body of the vehicle. The bell crank has a plurality of slots configured for receiving a top link connected to an implement of the vehicle. Further, a feedback link has a first end and a second end, and the first end of the feedback link being connected to the bell crank. A feedback rocker is pivotally mounted on body of the vehicle and the feedback rocker has plurality of slots configured to receive the second end of the feedback link. The feedback rocker is movable about its pivot point depending upon force experienced by the implement, and ratio of movement of feedback rocker depends upon the slot to which the feedback link is adapted. A linkage assembly interconnects a control valve with the feedback rocker, the control valve responsive to draft control requirement set by an operator and movement of the feedback rocker to lift and lower the implement.
[008] In an embodiment of the invention, the feedback rocker comprises plurality of slots positioned in a vertical configuration.
[009] In another embodiment of the invention, the system has a draft control lever operated by a user for setting desired limits on draft of the implement.
[010] In a further embodiment of the invention, the system comprises an actuating link connected to the draft control lever, and positioned between the linkage assembly and the control valve, for controlling the opening of the control valve based on position of the draft control lever.
[011] In a further embodiment of the invention, the control valve comprises a hydraulic control valve having a spool housed inside a cylinder such that pivotal movement of the feedback rocker causes the spool to move inside the cylinder, thereby controlling the implement.
BRIEF DESCRIPTION OF THE DRAWINGS
[012] Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.
Figure 1 illustrates an exploded view of a system for draft load control of an implement mounted on rear-side of a work vehicle, in accordance with an embodiment of the invention.
Figure 2 illustrates a perspective view of the system, in accordance with an embodiment of the invention.
Figure 3 illustrates a magnified perspective view of the system, in accordance with an embodiment of the invention.
Figure 4 illustrates a side view of the system with a feedback link being attached to a third slot on a feedback rocker, in accordance with an embodiment of the invention.
Figure 5 illustrates a side view of the system with the feedback link being attached to a first slot on the feedback rocker, in accordance with an embodiment of the invention.
Figure 6 illustrates a side view of the system with the feedback link being attached to a second slot on the feedback rocker, in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION
[013] The present invention relates to a system for draft load control of an implement mounted on a work vehicle.
[014] Figures 1 and 2 illustrate a system 100 for draft control of an implement mounted on rear-side of a work vehicle. The work vehicle is a tractor type vehicle engaged in farm operations and is capable of receiving and operating various farm implements such as a tiller, a plougher, a seeding implement etc. The implement is connected to the rear side of the tractor by means of a three-point hitch system having a top link (not shown), and two lower links (not shown), wherein at least the lower links are controlled through vehicle hydraulics.
[015] The system comprises a sensing assembly 10, a bell crank 110, a feedback rocker 130, a linkage assembly 140 and a control valve 150. As shown, the bell crank 110 is pivotally mounted on the sensing assembly. The sensing assembly is mounted on rear-side of the vehicle. The bell crank 110 has plurality of slots 112 configured to receive an end of a top link (not shown) while another end of the top link is connected to the implement. Since the top link is connected to the implement and the bell crank 110, any movement, especially vertical movement in the implement is transmitted to the bell crank 110, resulting in the bell crank 110 moving pivotally along pivotal mounting of the bell crank 110. If the implement moves vertically downward such as when encountering a soft spot on the ground, it results in the bell crank 110 pivotally moving towards the vehicle rear, and if the implement moves vertically upward such as on impact with a hard surface, the bell crank 110 pivotally moves towards the vehicle front.
[016] In an embodiment, the plurality of slots 112 on the bell crank comprise a first pair of slots 112A and a second pair of slots 112B configured to receive the top link. The first pair of slots 112A is located further from the pivotal mounting of the bell crank 110 than the second pair of slots 112B. This means that when the top link is attached at the first pair of slots 112A of the bell crank 110, the point of force transfer from the top link to the bell crank 110 will have a higher effective radius about the pivoted mounting of the bell crank 110, than when the top link is attached at the second pair of slots 112B of the bell crank 110.
[017] As further illustrated in Figure 1 and Figure 2, the system 100 has a feedback link 120 having a first end 120a and a second end 120b. The first end 120a of the feedback link 120 is connected to the bell crank 110. In an embodiment, the feedback link 120 has a longitudinal portion extending from the first end 120a, and a transversal portion extending from the longitudinal portion to the second end 120b.
[018] The system 100 has a feedback rocker 130 that is pivotally mounted on body of the vehicle. The feedback rocker 130 is a metallic plate having plurality of slots 132 positioned and spaced apart in a vertical configuration, and the slots 132 are configured to receive the second end 120b of the feedback link 120, thereby connecting the feedback rocker 130 to the bell crank 110. In an embodiment, the second end 120b of the feedback link 120 is selectively adapted to one of the slots 132. To facilitate the selective adaptation of the feedback link 120 to one of the slots, in an embodiment, the second end of 120b of the feedback link 120 has provisions for receiving fasteners such as clevis pins which secure the connection of the second end 120b of the feedback link 120 to the slots 132 on the feedback rocker 130. As a result, movement in the implement effects the pivoted movement of the bell crank 110, and this pivoted movement of the bell crank 110 effects a pivotal movement of the feedback rocker 130 along the pivotal mounting of the feedback rocker 130 via the feedback link 120. In an embodiment, the plurality of slots 132 on the feedback rocker 130 comprises a first slot 132A, a second slot 132B and a third slot 132C configured to receive the second end 120b of the feedback link 120. As also illustrated in Figure 3, the first slot 132A is located closest to the pivotal mounting of the feedback rocker 130, while the third slot 132C is located furthest to the pivotal mounting of the feedback rocker 130, and the second slot 132B is located at an intermediate length from the pivotal mounting of the feedback rocker 130 between the first slot 132A and the third slot 132C.
[019] Accordingly, ratio of movement will depend upon the slot to which the feedback link 120 is adapted. In this regard, when the second end 120b of the feedback link 120 is attached at the third slot 132C of the feedback rocker 130, movement from the feedback link 120 will cause the feedback rocker 130 to have a higher effective radius about the pivotal mounting of the feedback rocker 130, than when the feedback link 120 is attached at the second slot 132B of the feedback rocker 130, which in turn will have a higher effective radius than when the feedback link 120 is attached at the first slot 132A of the feedback rocker 130.
[020] The system 100 further has a linkage assembly 140 that connects the feedback rocker 130 to a control valve 150. The feedback rocker 130 is connected to the linkage assembly 140 via one or more fasteners such that rotation of the feedback rocker 130 causes movement of the linkage assembly 140. In an embodiment, the linkage assembly 140 comprises of a linkage spring 142 and a link draft 144. In operation, any movement in the implement is transmitted to the bell crank 110 via the top link, then the pivoted movement of the bell crank 110 is transmitted to the feedback rocker 130 by the feedback link 120, the resulting pivotal movement of the feedback rocker 130 is transmitted to the control valve 150 by the linkage assembly 140, and the control valve 150 then controls the implement accordingly. The linkage spring 142 acts as a shock absorber and ensures that shocks from the feedback rocker 130 do not reach the control valve 150.
[021] In an embodiment, the control valve 150 comprises a hydraulic type control valve having a spool housed inside a cylinder. The pivotal movement of the feedback rocker 130 causes the spool to move inside the cylinder, and the implement is then controlled based on the movement of this spool.
[022] In one configuration, the top link is received at the first slot 112A of the bell crank 110 and the second end 120b of the feedback link 120 is received at the third slot 132C of the feedback rocker 130 as illustrated in Figure 4. In such a configuration, effective movement of the feedback rocker 130 due to force experienced by the bell crank 110 is the highest. This ensures that any movement of the implement results in a relatively high movement of the spool of the control valve 150, hence providing draft control with a high sensitivity. Draft control with high sensitivity will cause the draft control system to respond to a low draft load on the implement. In soft soil, soil resistance on implement is less and variation of draft load is also quite less, and a higher sensitivity would allow tillage depth variation even in soft soil. Due to high sensitivity of draft control, any movement of the implement will result in greater movement of the spool, as compared to a low sensitivity of draft control where movement of the implement will result in a smaller movement of the spool. Thus, high sensitivity of draft control is best suited for farming operations on very soft soil.
[023] In another configuration, the top link is received at the second slot 112B of the bell crank 110 and the second end 120b of the feedback link 120 is received at the first slot 132A of the feedback rocker 130 as illustrated in Figure 5. In such a configuration, effective movement of the feedback rocker 130 due to force experienced by the bell crank is the lowest. This ensures that any movement of the implement results in a relatively low movement of the spool of the control valve 150, hence providing draft control with a low sensitivity. Draft control with low sensitivity is best suited for farming operations on hard soil. Draft control with low sensitivity will cause the draft control system to respond to a high draft load on the implement. On hard soil, soil resistance on implement is high and variation of draft load is also quite high, and would lead to large variation in top link force causing system hunting. Due to low sensitivity of draft control, any movement of the implement will result in relatively low movement of the spool. This is because for hard soil operation, draft control sensitivity should be low. Thus, low sensitivity of draft control is best suited for farming operations on very hard soil.
[024] Further, the present invention enables other configurations, which are suitable particularly for intermediate soil types, wherein the top link can be selectively adapted to the bell crank 110 and the feedback link 120 can be selectively adapted to the feedback rocker 130 to achieve intermediate sensitivity between high sensitivity and low sensitivity. For configurations for the intermediate soil types, the top link can be received by the first slot 112A of the bell crank 110 and the second end 120b of the feedback link 120 can be received by first slot 132A of the feedback rocker 130, or the top link can be received by the first slot 112A of the bell crank 110 and the second end 120b of the feedback link 120 can be received by the second slot 132B of the feedback rocker 130 as referenced in Figure 6, or the top link can be received by the second slot 112B of the bell crank 110 and the second end 120b of the feedback link 120 can be received by the second slot 132B of the feedback rocker 130, or the top link can be received by the second slot 112B of the bell crank 110 and the second end 120b of the feedback link 120 can be received by the third slot 132C of the feedback rocker 130. All these configurations will provide the system 100 with an intermediate sensitivity between the high sensitivity and the low sensitivity, appropriate for intermediate or medium soil types. Thus, combination of both bell crank slots and three slots of the feedback rocker provide total six modes or levels of sensitivity in the system 100, wherein the top link at first slot 112A of the bell crank 110 and feedback link 120 at the third slot 132C of the feedback rocker 130 is the appropriate combination for high sensitivity, the top link at second slot 112B of the bell crank 110 and feedback link 120 at the first slot 132A of the feedback rocker 130 is the appropriate combination for low sensitivity, and remaining configurations as discussed hereinabove can be used for medium or intermediate soil operation. Advantageously, the user can arrange the top link in the bell crank 110 and the second end 120b of the feedback link 120 in the feedback rocker 130 causing the sensitivity to change in accordance with the requirements of the soil type and the geographical conditions.
[025] Further, as shown, a draft control lever 160 is provided/mounted in a vehicle compartment which can be operated by the user for setting desired limits on draft of the implement. The draft control lever 160 is connected to an actuating link 162 that is positioned between the linkage assembly 140 and the control valve 150 and the control valve is responsive to draft control requirement set by an operator through the draft control lever, and movement of the feedback rocker to lift and lower the implement. During field operation with draft control, operator sets the draft control lever in quadrant to a particular level based on its requirement. When the draft control lever is set, it proportionately translates the motion and pushes the control valve spool through link connected to spool. When top link receives higher load viz. implement is overloaded due to hard soil condition, it generates more movement in bell crank which results in further movement of the spool causing the implement to lift. The lifting continues until spool return to its original position. Similarly, when the top link experiences less load due to soft or intermediate soil condition, it generates less movement in bell crank which results in corresponding further movement of the spool causing the implement to lift. The lifting continues until spool return to its original position.
[026] Advantageously, the present invention provides a system which can be configured for multiple levels of sensitivity in draft control. Multiple levels of sensitivity, when appropriately selected by the user, ensures high productivity and performance in field operations for all soil types and conditions. The different levels of sensitivity further ensure that there is minimum jerk in the control of the implement, and therefore the vehicle, reducing user fatigue.
[027] Further, the system of the present invention provides precise control of the implement, ensuring that all field operations such as tilling, ploughing, seeding etc can be carried out as desired by the user. The user does not require any special training to apply and utilise the different levels of sensitivity, and any user with an understanding of the conventional draft control systems can easily use the system of the present invention.
[028] Furthermore, the system of the present invention does not require any design modifications in the work vehicle or change in configurations of the other elements of the vehicle hydraulics, or any additional electronic components, and is therefore easier and cheaper to apply while having better reliability and serviceability.
[029] While the present invention has been described with respect to certain embodiments, it will be apparent to those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims.