Claims:WE CLAIM:
1. A variable linkage hand accelerator system (100), the system (100) comprising
a hand accelerator lever (10) having a length of first distance (A) mounted on a steering column of a vehicle;
a hand accelerator fork pin (20) connected to the hand accelerator lever (10) at first end (22) of the hand accelerator fork pin (20);
a cross shaft assembly lever (30) connected to a connection point (24) of the hand accelerator fork pin (20);
a pivot (42) configured at a bottom portion of the cross shaft assembly lever (30), the pivot (42) is connected to a foot pedal assembly (50) of the vehicle, and
a cross shaft bracket hole (44) configured on the cross shaft assembly lever (30) at a fourth distance (D) from the pivot (42);
the hand accelerator fork pin (20) rotates in a first direction about a first axis (Ha) thereby rotating the cross shaft assembly lever (30) in second direction about a third axis (Hc), the connection point (24) changes at each rotation of the hand accelerator lever (10) and gives the variable ratio.

2. The system (100) as claimed in claim 1, wherein the cross shaft assembly lever (30) has a connecting link (40) connected thereto, a first end of the connecting link (40) is connected at the cross shaft bracket hole (44).

3. The system (100) as claimed in claim 1, wherein the cross shaft assembly lever (30) and the hand accelerator fork pin (20) have a variable second distance (B) therebetween.

4. The system (100) as claimed in claim 1, wherein the pivot (42) is configured at a variable third distance (C) from second end of the hand accelerator fork pin (20).

5. The system (100) as claimed in claim 1, wherein the first axis (Ha) passes through a centre of the hand accelerator fork pin (20).

6. The system (100) as claimed in claim 1, wherein the cross shaft assembly lever (30) includes a second axis (Hb) passing through a centre portion thereof.

7. The system (100) as claimed in claim 1 or 6, wherein the third axis (Hc) passes through a centre of the pivot (42), the third axis (Hc) is perpendicular to the second axis (Hb).

8. The system (100) as claimed in claim 1 or 6, wherein the cross shaft assembly lever (30) has an angular orientation (O) with respect to the second axis (Hb).

9. The system (100) as claimed in claim 1, wherein the hand accelerator fork pin (20) is connected to the hand accelerator lever (10) through a high idle adjustable stopper bolt (15) placed at a junction between the hand accelerator fork pin (20) and the hand accelerator lever (10).
Dated this 06th day of August, 2021
For MAHINDRA & MAHINDRA LIMITED
By their Agent

GIRISH VIJAYANAND SHETH IN/PA- 1022
KRISHNA & SAURASTRI ASSOCIATES LLP
, Description:FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003

COMPLETE SPECIFICATION

[SEE SECTION 10, RULE 13]

A VARIABLE LINKAGE HAND ACCELERATOR SYSTEM;

MAHINDRA & MAHINDRA LIMITED, A COMPANY REGISTERED UNDER THE INDIAN COMPANIES ACT, 1913, HAVING ADDRESS AT MAHINDRA RESEARCH VALLEY, MAHINDRA WORLD CITY, PLOT NO: 41/1, P.O. – ANJUR, CHENGALPATTU – 603004, DIST. – KANCHEEPURAM, TAMIL NADU, INDIA

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE NATURE OF THIS INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a hand accelerator linkage of farm vehicles and more particularly, to a variable linkage hand accelerator system for farm vehicles.

BACKGROUND OF THE INVENTION
Farm vehicles generally belong to the category of heavy duty vehicles. Such vehicles need high efforts of user for vehicle operations. The efforts required for vehicle operations depend on the location and distance of operating lever from the user. Longer the distance of operating levers, higher the efforts required by the user. More operating lever travel and Longer distance is required to reduce the High efforts by the user. Accordingly, ergonomic design of operating levers is important for comfortable operations of the Farm vehicles.
In a farm vehicle such as tractor, the acceleration is also controlled by hand operated levers in addition to foot accelerated pedal. The advantage of hand accelerator lever to operate the tractor at constant speed by placing the lever at required position. Referring to FIG. 1, the fixed Hand Accelerator linkage is shown. The ratio shown in FIG. 1 is the ratio of Hand Accelerator lever length (A) and output Clevis length (B). In fixed linkage ratio Lever travel reduction causes the increase of effort and vice versa. This linkage ratio is an important relation in design calculation for Tractor Hand accelerator system. It is to be noted here that decrease in the Linkage ratio, results in less travel but increase in the effort required from the user. To increase in the Linkage ratio, longer length of Hand Accelerator Lever (A) is needed that reduces the lever effort which is good from user effort point of view. However, the longer hand accelerator lever creates the fouling with operator knee due to space constrain in small platform tractor.
There are several ways to decrease the ratio without changing the hand accelerator lever length (A) that includes increasing the clevis length (B). However, increased clevis length may interfere with the surrounding parts like a fuel tank. Further, the longer Hand accelerator lever (A) creates the vibrations in lever during tractor running condition. This issue may be solved by adding weight in the form of additional mountings that leads to increase in the cost of lever assembly. Furthermore, hand accelerator lever travel increase affects the ergonomic operating zone which is long run painful usage to the customer.
Accordingly, there is need of a linkage that facilitates less travel of hand accelerator without compromising the effort i.e. Ergonomic Effort Zone.
SUMMARY OF THE INVENTION
The present invention relates to a variable linkage hand accelerator system that includes a hand accelerator lever having a length of first distance mounted on a steering column of a vehicle; a hand accelerator fork pin is connected to the hand accelerator lever at first end of the hand accelerator fork pin. A cross shaft assembly lever is connected to the hand accelerator fork pin at a connection point of the hand accelerator fork pin and the cross shaft assembly lever. A pivot is configured at a bottom portion of the cross shaft assembly lever. The pivot has a foot pedal assembly attached thereto. A cross shaft bracket hole is configured on the cross shaft assembly lever at a fourth distance from the pivot. The hand accelerator fork pin rotates in first direction about a first axis thereby rotating the cross shaft assembly rotates in second direction about a third axis. The connection point changes at each rotation of the hand accelerator lever and gives the variable ratio. A connecting link is connected to the cross shaft assembly lever. A first end of the connecting link is connected at the cross shaft bracket hole. The cross shaft assembly lever and the hand accelerator fork pin have a variable second distance therebetween. The pivot is configured at a variable third distance from second end of the hand accelerator fork pin. The first axis passes through a centre of the hand accelerator fork pin. The cross shaft assembly lever includes a second axis passing through a centre portion thereof. The third axis passes through a centre of the pivot. The third axis is perpendicular to the second axis. The cross shaft assembly lever has an angular orientation with respect to the second axis. The hand accelerator fork pin is connected to the hand accelerator lever through a high idle adjustable stopper bolt placed at a junction between the hand accelerator fork pin and the hand accelerator lever.
BRIEF DESCRIPTION OF DRAWING
FIG. 1 illustrates a fixed linkage hand accelerator lever of the prior art;
FIG. 2 illustrates a variable linkage system for hand accelerator lever in accordance with an embodiment of the present invention;
FIGS. 3A and 3B connection between the elements of the system of FIG. 2;
FIG. 4 illustrates operation of the elements of the system of FIG. 2;
FIG. 5 illustrates graphical representation of the hand accelerator lever travel with respect to a system of the prior art;
FIG. 6 illustrates graphical representation of the hand accelerator lever travel with respect to a system of the present invention; and
FIG. 7 illustrates a 3d configuration of the linkage of FIG. 2.
DETAILED DESCRIPTION OF THE INVENTION
In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which shown by way of illustration specific embodiments that may be practiced. These embodiments are described in sufficient detail to enable a person skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized, and that logical, mechanical, and other changes may be made within the scope of the embodiments.
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 is not intended to limit the scope of the invention to these embodiments.
The foregoing and other features of embodiments of the present invention will become more apparent from the following detailed description of embodiments when read in conjunction with the accompanying drawings. In the drawings, like reference numerals refer to like elements.
FIG. 2 illustrates a variable linkage hand accelerator system (100) in accordance with an embodiment of the present invention. The system (100) includes a hand accelerator lever (10) mounted on a steering column. A hand accelerator fork pin (20) is connected to the hand accelerator lever (10) at first end (22) of the hand accelerator fork pin (20) through a high idle adjustable stopper bolt (15). A cross shaft assembly lever (30) is connected to the hand accelerator fork pin (20) at second end of the hand accelerator fork pin (20). A connecting link (40) is connected to the cross shaft assembly lever (30) at a first end of the connecting link (40).
In accordance with the present invention, a foot pedal assembly (50) is connected to the pivot (42) configured at bottom portion of the cross shaft assembly lever (30). The foot pedal assembly (50) includes a foot accelerator link (51) is connected to the pivot (42) at one end of the foot accelerator link (51). The foot accelerator link (50) includes an intermediate pivot (52) at another end of thereof. The intermediate pivot (52) is mounted on clutch housing with the help of bolt. A foot pedal adjustable connecting link (54) is assembled between bottom hole of the intermediate pivot (52). The foot pedal adjustable connecting link (54) is connected to a shaft (56) that also includes a foot pedal (58) connected thereto. A tension spring (60) is assembled to the shaft (56) of the foot pedal (58) to return the foot pedal (58) position to default when operator removes the foot from foot pedal (58).
A motion of the hand accelerator lever (10) is transmitted to a hand accelerator fork pin (20). The high idle adjustable stopper bolt (15) placed on bracket with welded nuts is positioned between the hand accelerator lever (10) and the hand accelerator fork pin (20). The high idle adjustable stopper bolt (15) is used to ensure the engine high idle operation in every setting and arrest further movement of the hand accelerator lever (10) to avoid damages in connecting link ends (40).
In accordance with an embodiment, the cross shaft assembly lever (30) has a connecting link (40) attached thereto at first ends of the connecting link (40) by a suitable connecting means. The connecting link (40) is connected at a cross shaft bracket hole (44) that is configured on the cross shaft assembly lever (30). The cross shaft bracket hole (44) is configured on the cross shaft assembly lever (30) at a distance (D) from a pivot (42). The pivot (42) is configured at a bottom portion of the cross shaft assembly lever (30). A second end of the connecting link (40) is connected to engine FIP lever to pull the lever during low and High Idle operation.
Referring to FIG. 3A and 3B, the rotation of the hand accelerator lever (10) having length (A) (first distance) moves the cross-shaft assembly lever (30) in a first direction. The first distance (A) is a distance between the first end point of the hand accelerator lever (10) that is connected to a steering column and a first axis (Ha) passing through the centre of the hand accelerator fork pin (20). In an embodiment, the first distance ranges between 230 to 240 mm. The cross shaft assembly lever (30) is positioned at a second distance (B) from the first axis. The second distance (B) is a distance between the first axis (Ha) and a second axis (Hb) passing through the cross shaft assembly lever (30). The distance between the outer surfaces of the hand accelerator fork pin (20) intersection on the cross shaft assembly lever (30) varies with the rotation of the system in first direction and second direction. In an embodiment, the second distance is variable distance that ranges between 35 to 50 mm.
Referring to FIG. 4 and 7, the pivot (42) configured at the bottom portion of the cross shaft assembly lever (30) has a third axis (Hc) passing through a centre portion thereof. The third axis (Hc) is perpendicular to the second axis (Hb). The angular orientation of the cross shaft assembly lever (30) with respect to the second axis (Hb) is O. In an embodiment, the O ranges between 150 to 210. This angle is reference angle to start the cross-shaft assembly lever (30) movement towards variable ratio. In an embodiment, the cross-shaft assembly lever (30) is placed in 2nd Quadrant (90~180°) plane. If the same cross shaft assembly lever (30) is placed in other Quadrant planes i.e. 1st plane (0°~90°) or 3rd plane (180°~270°) and 4th plane (270°~360°) the best variable linkage ratio may not be achieved since orientation of the cross shaft assembly lever (30) and the hand accelerator fork pin (20) equally contribute to get the variable ratio (refer Table 1). The movement of the cross shaft assembly lever (30) and the hand accelerator fork pin (20) gradually decreases and then increases with respect to the pivot center (42). During this travel a non-variable point in both the cross shaft assembly lever (30) and the hand accelerator fork pin (20) is located. For constant linkage this point (70) is same throughout the travel. However, in the variable linkage of the present invention, this point (70) gets replicated in the 3d curve (72) movement.

Table 1
The distance between the connecting point (24) of the cross shaft assembly lever (30) and the hand accelerator fork pin (20) to the pivot center (42) is a third distance (C) which is a variable distance. The third distance (C) varies according to the movement of the hand accelerator lever (10). In an embodiment, the third distance ranges between 65 to 72 mm. A cross shaft bracket hole (44) is fixed on the cross shaft assembly lever (30) at a fourth distance (D) from the pivot (42). In an embodiment, the fourth distance ranges between 47 to 53 mm.

The hand accelerator lever (10) rotates about the first axis (Ha) passing centrally through the hand accelerator fork pin (20) in first direction. The hand accelerator lever pin (20) is attached to a cross shaft assembly lever (30). The hand accelerator fork pin (20) is pushed at rear side and rotates the cross shaft assembly lever (30) during operation of the hand accelerator lever (10) from low to high idle. During the releasing time of the hand accelerator lever (10), the hand accelerator fork pin (20) moves freely and the cross shaft assembly lever (30) returns by the linkage return force. The hand accelerator fork pin (20) rotates in the second direction and transmits the motion to the cross shaft assembly lever (30). It is to be noted here that the first direction is opposite to that of the second direction.
In accordance with an embodiment of the present invention, the hand accelerator lever (10) and the hand accelerator fork pin (20) rotate about a first axis (Ha) to move the hand accelerator lever (10) from low to high idle operation in the first direction. At the same time the cross shaft assembly lever (30) rotates in the second direction about the third axis (Hc) to achieve the low to high idle acceleration. It is to be noted here that the connection point (24) of the hand accelerator fork pin (20) and the cross shaft assembly lever (30) changes at each rotation of the hand accelerator lever (10) and gives the variable ratio.
In accordance with the present invention, the fixed values of the hand accelerator lever length (A) and the distance of the cross shaft bracket hole (44) from the pivot (42) that is the fourth distance (D) helps to decide the overall linkage ratio. Further, the functional centre distance of (B) and (C) are also important parameter to decide the variable linkage ratio. In variable linkage ratio, the ratio is changed by means of variable centre distance at each degree of cross shaft assembly lever (30) movement from a pivot (42). The hand accelerator fork pin (20) is follower of the cross-shaft assembly lever (30) during the lever travel. The user may feel the less effort during deceleration compared to the acceleration due to the connecting point of the hand accelerator fork pin (20) and the cross shaft assembly lever (30).
Further, again referring to FIG. 2, when the foot pedal (58) is pressed by the user, the shaft (56) transmits the motion to the adjustable connecting link (54). The adjustable connecting link (54) transfers the motion to the intermediate pivot (52). The foot accelerator link (51) connected to the intermediate pivot (52) is pulled in upward direction thereby rotating the pivot (42) in second direction. If the foot pedal (58) is pressed further, the pivot (42) rotates upward and away from the hand accelerator fork pin (20).
When operator pulls the hand accelerator lever (10) in first direction about the Ha axis, the hand accelerator lever (10) rotates the cross-shaft assembly lever (30) in second direction about Hc axis. The foot accelerator link (51) does not move due to the slot provided in the pivot (42) that restricts free rotation about the Hc axis. The foot accelerator assembly (50) does not rotate while operating the hand accelerator lever (10). The foot pedal assembly (50) and the hand accelerator system (100) of the present invention work independently of each other.
Referring to FIG. 5 (prior art), the parameters A, B, C & D are fixed values which gives the fixed linkage ratio throughout angular moment of the hand accelerator lever (10). In this case, the travel and effort and cannot be optimized as it is the fixed ratio. To increase in the Linkage ratio and to reduce the lever effort, longer hand accelerator lever length (A) is required. The longer hand accelerator lever length (A) may create the fouling with operator knee. However, there is another way to decrease the ratio without changing the hand accelerator lever length (A) and that is increasing the clevis length (B). However, increased clevis length (B) may interference with surrounding parts in small tractor.
To overcome this drawback the variable linkage ratio is used. Referring to FIG. 6, while the user moves the hand accelerator lever (10) from low idle to high idle, the gradual decrease in hand accelerator lever ratio and gradual increase of cross shaft ratio is required. The hand accelerator lever (10) moves in the first direction and the cross shaft assembly lever (30) moves in second direction. The overall linkage ratio is gradually reduced to achieve less angular movement. In variable linkage ratio concept, the user can operate the less angular travel with a marginal increased in hand accelerator effort, which improves the driver's operational comfort thereby avoiding the foul of driver knee to hand accelerator lever.
Advantageously, the variable ratio is used for reducing the hand accelerator lever effort. The hand accelerator lever ratio is required to increase gradually, and cross shaft ratio is required to gradually decrease while the user moves the hand accelerator lever (10) from low idle to high idle. The hand accelerator lever (10) moves in second direction & the cross shaft assembly lever (30) moves first direction. The Overall linkage ratio is gradually increased to achieve less lever effort.
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 distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative, of the invention and not as a limitation. The exemplary embodiments described in this specification are intended merely to provide an understanding of various manners in which these embodiments may be used and to further enable the skilled person in the relevant art to practice the invention.
Although, the embodiments presented in this disclosure have been described in terms of its preferred embodiments, the skilled person in the art would readily recognize that these embodiments can be applied with modifications possible within the scope of the present invention as described in this specification by making innumerable changes, variations, modifications, alterations and/or integrations in terms of materials and method used to configure, manufacture and assemble various constituents, components, subassemblies and assemblies, in terms of their size, shapes, orientations and interrelationships without departing from the scope and spirit of the present invention.
The numerical values given of various physical parameters, dimensions and quantities are only approximate values and it is envisaged that the values higher or lower than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the disclosure unless there is a statement in the specification to the contrary.
The linkage of the present invention facilitates quick Sensitive Response during entire travel of acceleration. The mechanical linkage hand accelerator is suitable for paddling application. The present invention may be used to reduce the high effort clutch and brake linkage application. The present invention facilitates altering the travel and effort based on requirement in low cost. The linkage of the present invention is easy for replacement and serviceable. The linkage of the present invention is adopted with Less packaging area.
LIST OF REFERENCE NUMERAL
100 Variable Linkage Hand Accelerator System
10 Hand Accelerator Lever
15 Adjustable Stopper Bolt
20 Hand Accelerator Fork Pin
24 Connection Point
30 Cross Shaft Assembly Lever
40 Connecting Link
42 Pivot
44 Cross Shaft Bracket Hole
50 Foot pedal assembly
51 foot accelerator link
52 Intermediate pivot
54 Adjustable connecting link
56 Shaft of foot pedal
58 Foot pedal
60 Tension Spring
Ha First Axis
Hb Second Axis
Hc Third Axis
A First Distance
B Second Distance
C Third Distance
D Forth Distance
O Angular Orientation