The embodiments herein generally relate to a draft force sensor for sensing forces, such as the draft forces applied by an implement hitch of an agricultural vehicle (tractor), more particularly to a draft force sensor assembly for a hitch system of an agricultural vehicle.
BACKGROUND
[002] Agricultural vehicles such as tractors, tow implements using a variety of hitches to connect the vehicle and the implement. One of the most common hitch is a three point hitch. It is called a three point hitch since it has three substantially parallel links or connections that extend between the agricultural vehicle (tractor) and the implement. These links permit the motion between the vehicle and the implement to be constrained to relative translation, and substantially prevent relative rotation.
[003] The three point hitch normally includes a draft sensing mechanism which provides a draft force signal to a control system which lowers and raises the implement as a function of sensed draft force and possibly as a function of other sensed parameters, such as position, engine speed, wheel slip, etc. Some known production draft sensing mechanisms have a number of moving parts that require periodic maintenance. This includes removing mud and dirt accumulation and lubricating a draft sensor plunger to prevent moisture and dirt contamination. In certain conditions, accumulated dirt and mud can prevent the required component movement and can cause wear of the moving parts and false draft force signals.
[004] Other known draft sensing mechanisms include expensive draft sensing pins, bending bars, and draft sensing shafts. Draft sensing pins require two instrument pins which increase the cost and decrease the reliability. Further, current draft sensing system measures deflections of a draft link mount straps to measure the draft force. These straps are large and a large number of parts are required to measure this force. Furthermore, the bending bar and the draft sensing shaft systems include moving parts and require a sealed compartment and a fair amount of space.

[005] Further, control devices are used with the agricultural tractors to allow the positioning of the implement being drawn or pushed to be automatically controlled, at least in part, on the basis of the detection of the force being applied to the implement. Automatic control is used for distributing the power correctly between the function of drawing, pushing or supporting the implement, and the function of positioning the implement at a predetermined position, typically the depth of penetration in the ground being worked. By way of example, such controls may use electronic pins mounted to one or both lower draft links of the three-point hitch to sense draft force.
[006] There are varieties of sensing and control devices available for providing the necessary control of implements coupled to the agricultural vehicles. However, these devices are typically mechanically complex, are expense to manufacture, and have electronics prone failures. Accordingly, it would be desirable to reduce the mechanical complexity and quantity of sensors used in the control of agricultural implements.
[007] Therefore, there exists a need for a draft force sensor assembly for a hitch system of an agricultural vehicle (tractor) which eliminates the aforementioned drawbacks.
OBJECTS
[008] The principal object of an embodiment of this invention is to provide a draft force sensor assembly for a hitch system of an agricultural vehicle (tractor).
[009] Another object of an embodiment of this invention is to provide the draft force sensor assembly for a hitch system which is very simple in construction, inexpensive, protected from wear and prevents oil leakage.
[0010] Yet another object of an embodiment of this invention is to provide the draft force sensor assembly for the hitch system in which the sensor is free to move within a predefined space and not connected to any

component of the vehicle or draft sensing mechanism, thereby achieving a floating sensor.
[0011] Still another object of an embodiment of this invention is to provide a draft force sensor assembly in which a draft force from the implement is converted into a linear motion of the sensor to control the hitch valve through a set of draft hydraulic linkages.
[0012] These and other objects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.
BRIEF DESCRIPTION OF DRAWINGS
[0013] The embodiments herein are illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:
[0014] FIG. 1 depicts a sectional view of a draft force sensor assembly for a hitch system of an agricultural vehicle, according to an embodiment of the invention as disclosed herein.

DETAILED DESCRIPTION
[0015] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[0016] The embodiments herein achieve a draft force sensor assembly for a hitch system of an agricultural vehicle (tractor). Further, the embodiments herein achieve the draft force sensor assembly for the hitch system which is very simple in construction, inexpensive and protected from wear. Furthermore, the embodiments herein achieve the draft force sensor assembly for the hitch system in which the sensor is free to move within a predefined space and not connected to any component of the vehicle or draft sensing mechanism, thereby achieving a floating sensor. Additionally, the embodiments herein achieve the draft force sensor assembly in which a draft force from the implement is converted into a linear motion of the sensor to control the hitch valve through a set of draft hydraulic linkages. Referring now to the drawings, and more particularly to FIG. 1, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.
[0017] FIG. 1 depicts a sectional view of a draft force sensor assembly for a hitch system of an agricultural vehicle, according to an embodiment of the invention as disclosed herein. In an embodiment, the draft force sensor assembly 100 is used in conjunction with an agricultural vehicle hitch system (not shown). The draft force sensor assembly 100 includes at least one draft element 102, a first upper end Ul, a first lower

end LI, a housing 104, a draft force sensor 106, hitch control valve 108, a plurality of draft linkages 110, a guide bracket 112, a rocker link 102c, an outer guide member 102o and an inner guide member 102i, a alien screw 102s, a spring 114, a sealing member, a head 120h, a draft link 122, a coupler spring 124, a draft coupler 126, a draft actuator 128, a bracket 130, and a screw nut 132.
[0018] The draft force sensor assembly 100 includes the draft element 102. The draft element 102 is connected towards a top link of the hitch system. The draft element 102 includes a first upper end Ul and a first lower end LI. In an embodiment, the draft element 102 is hingedly secured to a guide bracket 112 provided on the vehicle at the first upper end Ul as shown in FIG. 1. Further, the draft element 102 includes a rocker link 102c disposed towards the first lower end LI. Further, the housing 104 is coupled the rocker link 102c through welding, thus the housing 104 and the rocker link 102c act as a single part rocker link (102). The housing 104 defines an outer guide member 102o, an inner guide member 102i and a central bore (not shown) which is in touch condition. Further, the spring 114 is disposed between the outer guide member 102o and the inner guide member 102L In an embodiment, the spring 114 is configured to be displaced between a compressed state and a normal or expanded state when the draft element 102 moves due to force of top link (not shown). The central bore is configured to receive an alien screw 102s. The alien screw 102s is connected to a screw nut 132 at one end and defines a head 120h on the other end. The head 120h of the Allen screw 102s is configured to transmit a linear motion of the draft element 102 to the draft force sensor 106 and in this state Rocker link 102, transmits force which pushes Allen screw head 102h, Outer cup 102o & sensor spring 114, which are acting as a single unit, i.e., the head 120h of the alien screw 102s pushes the draft force sensor 106 so that the draft sensor 106 moves linearly within a space therein.

[0019] In an embodiment, the rocker link 102c includes at least one opening to hinge the top link of the hitch system to the draft element 102. In an embodiment, the rocker link 102c includes at least three openings to accommodate the top link of the hitch system based on desired soil operating conditions.
[0020] The draft force sensor 106 adapted to be received by a portion of the vehicle. In an embodiment, the draft force sensor 106 includes a spherical face on one end. The draft force sensor 106 is adapted to transfer the linear motion of the draft element 102 to the hitch control unit 108 through the plurality of draft linkages 110. The draft force sensor 106 is a touch based sensor which is independently assembled between the housing 104 and the plurality of draft linkages 110. In an embodiment, the draft force sensor 106 is adapted to be disposed between the head 120h defined at the first lower end LI of the draft element 102 and the draft link 122 defined away and towards the plurality of draft linkages 110 of the hitch system. In an embodiment, the draft force sensor 106 is at least a floating sensor adapted to transmit the linear motion of the draft element 102 to the hitch control valve 108 through the plurality of draft linkages 110.
[0021] The draft force sensor assembly 100 further includes the plurality of draft linkages 110. The plurality of draft linkages 110 includes a draft link 122, a coupler spring 124, a draft coupler 126, and a draft actuator 128. The draft link 122 is provided in contact with the draft force sensor 106. The draft link 122 is hinged to the vehicle frame (not shown) at a second upper end U2. The hinge arrangement provides a pivotal movement to the draft link 122. Further, the draft link 122 includes a second lower end L2 which is adapted to be displaced by the draft force sensor 106. The coupler spring 124 coupled to the draft link 122 so that any linear motion provided to the draft link 122 is transmitted completely to the draft coupler 126. The draft coupler 126 coupled to the coupler spring 124 at one end, further the draft actuator 128 is provided in

communication with the draft coupler 126. The linear motion offered to the draft coupler 126 by the coupler spring 124 is transmitted to the draft actuator 128 to operate the hitch control valve 108 of the vehicle to control a hitch system of the vehicle.
[0022] The draft force sensor assembly 100 further includes the bush 116. In an embodiment, the draft force sensor 106 is mounted within the bush 116 disposed at predetermined position of the vehicle. In an embodiment, the bush 116 is made up of hardened material. However, it is also within the scope of the invention to provide any type of material for the bush 116 without otherwise deterring the intended function of supporting respectively, as can be deduced from the description and corresponding drawings. Further, the bush 116 includes a sealing member 118 which is disposed around the draft force sensor 106 to provide oil sealing for the draft force sensor 106. In an embodiment, the sealing member 118 is an O-ring.
[0023] Thus, the draft force sensor 106 mounted independently between the draft element 102 and the plurality of draft linkages 110 is configured to transmit the force or load acting on the top link of the hitch system to the hitch control valve 108 so that the effective working of tractor hydraulic system is achieved. The draft force sensor 106 is adapted to have a touch contact between the draft element 102 and the draft linkages 110 which provides in no physical constraint and avoids any loss in motion transfer.
[0024] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of

limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

CLAIMS
We claim,

1. A draft force sensor assembly 100 for a hitch system of an agricultural
vehicle, comprising:
a draft force sensor 106 having a first end provided in communication with a draft element 102 and a second end provided in communication with a plurality of draft linkages 110 of said hitch system of said vehicle; and
a hitch control valve 108 provided in communication with said draft force sensor 106, wherein,
said draft force sensor 106 is configured to actuate said hitch control valve 108 through said plurality of draft linkages 110 to control said hitch system.
2. The draft force sensor assembly 100 as claimed in claim 1, wherein said draft element 102 includes a first upper end Ul adapted to be coupled to a top link of said hitch system and a first lower end LI coupled to a housing 104, said draft element 102 is configured to provide a linear motion to said draft force sensor 106.
3. The draft force sensor assembly 100 as claimed in claim 1, wherein said draft element 102 includes:
a rocker link 102c defined between said first upper end Ul and said first lower end LI;
said housing 104 coupled to said lower end LI of said rocker link 102c, said housing 104 having an outer guide member 102o and an inner guide member 102i and defining a central bore to receive an alien screw 102s;

at least one spring 114 disposed between said outer guide member 102o and said inner guide member 102i of said housing 104;
said alien screw 102s connected to a screw nut 132 at one end and defining a head 120h on other end; and
said head 120h of said alien screw 102s configured to transmit said linear motion of said draft element 102 to said draft force sensor 106.
4. The draft force sensor assembly 100 as claimed in claim 1, wherein said draft force sensor 106 includes a surface contact between a draft link 122 and said head 120h, said draft force sensor 106 is at least an independently floating sensor adapted to transmit said linear motion of said draft element 102 to said hitch control valve 108 through said plurality of draft linkages 110.
5. The draft force sensor assembly 100 as claimed in claim 1, wherein said draft force sensor 106 is at least a tubular member having a spherical face towards a first end and a second end of said draft force sensor 106.
6. The draft force sensor assembly 100 as claimed in claim 1, wherein said plurality of draft linkages 110 includes:
said draft link 122 provided in contact with said draft force sensor 106, said draft link 122 is hinged to a vehicle frame at a second upper end U2 and is adapted to be displaced by said draft force sensor 106 at a second lower end L2;
a coupler spring 124 coupled to said draft link 122;
a draft coupler 126 coupled to said coupler spring 124, said coupler spring 124 is configured to transmit a displacement of said draft link 122 to said draft coupler 126; and
a draft actuator 128 in communication with said draft coupler 126, wherein,

said draft actuator 128 is adapted to operate said hitch control valve 108 to control said hitch system of said vehicle.
7. The draft force sensor assembly 100 as claimed in claim 1, wherein said draft force sensor 106 is mounted within a bush 116 disposed at predetermined position of said vehicle, said draft force sensor 106 moves linearly within said bush 116 when pushed by said alien screw 102s, said bush 116 includes a sealing member 118 which is disposed around said draft force sensor 106 to provide oil sealing for said draft force sensor 106.
8. The draft force sensor assembly 100 as claimed in claim 3, wherein said housing 104 is adapted to slide within a bracket 130 which is coupled to said vehicle at a predetermined position.
9. The draft force sensor assembly 100 as claimed in claim 3, wherein said spring 114 is configured to be displaced between a compressed state and normal or expanded state when said draft element 102 is displaced by said top link of said hitch system.