DESC:STEERING GEARBOX WITH IMPROVED STEERING RETURN-ABILITY
FIELD OF INVENTION:
[001] The present subject matter described herein, relates to a steering gearbox of a vehicle, and, in particular, to a manual steering gearbox with mechanical assist mechanism with improved steering return-ability and hence improving straight resilience after a vehicle turns. Structure is adopted to enable Steering gear to have functions of increasing aligning force during the steering.
BACKGROUND AND PRIOR ART:
[002] The driver controls vehicle through steering wheel in the driver cabin. Further, the steering wheel is connected with a steering system which turns the vehicle. The driver rotates the steering wheel to turn the vehicle. Once the vehicle is turned (left/right direction), the steering should return to its original position or center position. Therefore, the steering return ability is required after turning the vehicle and vehicle should move in a straight path. However, due to vehicle geometry and other such factors, such as friction within Steering gearbox as well as in the steering column itself, the steering wheel often does not return to a near central neutral position without some effort by the driver of the vehicle. It is annoying to the driver of the vehicle particularly during slight turns or while driving at highway speeds. Therefore, there is a need for a steering wheel return assist mechanism to return the steering wheel to the near central neutral position after a turn to facilitate ease in handling of the vehicle.
[003] Indian Patent publication 258459 discloses a device for steering return-ability and centering for a vehicle comprising at least two spiral springs, an arbor, case assembly and mounting means. Wherein said spiral springs are provided on said arbor coaxially and the unit of said springs and arbor is assembled inside the said casing assembly. Said arbor is adopted to be rotatably engaged with steering column/wheel and said casing assembly is mounted on mounting means. When steering wheel is turned in either direction the springs provide return torque so that the wheel comes back to neutral position. The invention thus provides steering return-ability in response to large steering wheel inputs and steering centering in response to spurious steering inputs, thus eliminating the need of providing positive caster in the suspension. The invention is compact and has least number of parts. This invention deals with the center mechanism in steering column with the help of two spiral springs. This invention suffers from the shortcoming that it pushes the steering shaft/column to make the steering in center position while the rack, pinion and tires remain in the same position. Further, the invention suffers from sudden backlash after releasing the steering wheel. In addition, the invention works with the steering column of the steering gearbox.
[004] Conventional manual Steering Gearbox does not have any support mechanism to improve Steering return-ability. Thus, there is requirement for assist mechanism in manual Steering gearbox to improve Steering return-ability. Currently, steering return-ability pertaining to Steering gear box is dependent on friction only considering vehicle geometry can’t be changed. One of the methods for minimizing friction is by increasing yoke clearance or by reducing yoke spring stiffness which can cause noise at several road conditions. Another method to improve the steering return-ability is by providing spiral springs in the steering shaft or column which has its own limitations. Thus, there is requirement to include an assist mechanism to improve steering return-ability for manual steering gearbox without compromising noise performance at vehicle level.
OBJECTS OF THE INVENTION:
[005] The principal object of the present subject matter is to provide an assist mechanism to support steering return-ability.
[006] Another object of the present subject matter is to provide doubled embedded helical spring into steering boot to generate return force to improve steering return-ability.
[007] Another object of the present subject matter is to provide doubled embedded spring at both locations (right and left) of the steering boot.
[008] Yet another object of the present subject matter is provide an assist mechanism for return-ability of the steering which is simple, inexpensive and efficiently works with the existing structure of the steering gear box.
SUMMARY OF THE INVENTION:
[009] The subject matter disclosed herein relates to a Manual Steering Gearbox with mechanical assist mechanism for steering return-ability improvement. In the present subject matter, an inner ball joint assembly of steering gear box has a ball joint for joining the rack bar and the tie rod. An assist mechanism, i.e., spring embedded steering boot is provided over the ball joint assembly. The steering boot has embedded helical spring. The spring embedded steering boot is connected with the rack housing from one end and with the tie rod on other end. The spring embedded steering boot has gradually increasing diameter for some part then constant diameter from one end to other end. The gradually increasing diameter helps coils of the spring and the spring embedded steering boot to insert into adjacent coils in the radial direction to allow complete rotation of the vehicle and to maintain the minimum turning radius of the vehicle. The assist mechanism, i.e., embedded spring which is provided in the steering boot to improve steering return-ability. During return of steering to center, the present mechanism generates return force on both sides, i.e., RH and LH to improve steering return-ability.
[0010] In order to further understand the characteristics and technical contents of the present subject matter, a description relating thereto will be made with reference to the accompanying drawings. However, the drawings are illustrative only but not used to limit scope of the present subject matter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
[0012] Fig. 1 illustrate steering gearbox with steering boot, in accordance with an embodiment of the present subject matter; and
[0013] Fig. 2 and 3 illustrate cross section of the steering gearbox with embedded spring in the steering boot, in accordance with an embodiment of the present subject matter.
[0014] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DESCRIPTION OF THE PREFERRED EMBODIMENTS:
[0015] The subject matter disclosed herein relates to a Manual Steering Gearbox with mechanical assist mechanism for steering return-ability improvement. In the present subject matter, an inner ball joint assembly of steering gear box has a ball joint for joining the rack bar and the tie rod. Further, a spring embedded steering boot is provided over the ball joint assembly. The spring embedded steering boot has embedded helical spring. The spring embedded steering boot is connected with the rack housing from one end and with the boot bush on the tie rod. Both the spring and the spring embedded steering boot have gradually increasing diameter for some part then constant diameter from one end to other end. The gradually increasing diameter helps coils of the spring and the spring embedded steering boot to insert into adjacent coils in the radial direction to allow complete rotation of the vehicle and to maintain the minimum turning radius of the vehicle. The assist mechanism, i.e., embedded spring which is provided in the steering boot to improve steering return-ability. During return of steering to center, the present mechanism generates return force on both sides, i.e., RH and LH to improve steering return-ability.
[0016] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter and are included within its spirit and scope. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.
[0017] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0018] The present subject matter relates to manual steering gear box of a vehicle. The steering gear box has a rack bar and pinion for rotating the steering gear box. The rack and pinion mechanism converts the rotational input of steering shaft into linear motion. The rack and pinion mechanism has a rack bar and a pinion for movement. The rack bar is connected with tie road via a ball joint assembly. When the driver rotates the steering wheel, the rotational force is transmitted to the steering shaft. The rotational force of the steering shaft is changed by a rack and a pinion gear mechanism in a linear direction to linearly move the rack bar.
[0019] Fig. 1 illustrates structure of the steering gearbox with steering boot, in accordance with the present subject matter. Fig. 2 and 3 illustrate the cross section of the steering boot, in accordance with an embodiment of the present subject matter. The manual steering gearbox has a rack bar, pinion gear, rack bush, tie rod, ball joint and steering boot to cover the ball joint. Figure 2 describes the assembly 200 of inner joint with steering boot. The inner ball joint 201 connects one end of tie rod 202 with rack bar 203. The tie rod 202 has spherical ball end 202a with engages with ball receiving housing 203a of the rack bar 203. The rack bar 203 has rack housing 208 which holds steering boot 205 from one end. The rack bar 203 moves left and right hand side inside the rack housing 208. The rack and pinion mechanism moves the rack bar 203 left and right hand side for turning the vehicle. A spring 206 is embedded in the steering boot 205. The spring 206 is in helical shape to store more energy. The spring 206 is made of highly tensile material as known in the art. Diameter of the spring 206 gradually increases from the one end to other end. During rotation of the steering shaft either on left hand side or on right hand side, the helical spring 206 with gradually increasing diameter compresses. During the compression of the helical spring 206 with gradually increasing diameter, coils of the helical spring 206 insert into the adjacent coils and superimposed in the circular/radial direction to provide enough space for rotation and maintaining the minimum turning radius of the vehicle. Compression of the helical spring stores elastic potential energy which pushes the rack bar into original position.
[0020] The inner ball joint 201 is covered with a steering boot 205. The steering boot 205 is a spring embedded steering boot 205 having an embedded spring in crest and trough of the steering boot 205. The spring embedded steering boot 205 has the embedded helical spring 206. The spring embedded steering boot 205 is made of high quality rubber. One end of the spring embedded steering boot 205 is connected with the rack housing 208 and other end is connected with the tie rod 202 with boot bush 207. The boot bush 207 restricts the movement of the spring embedded steering boot 205 on the tie rod 202. Diameter of the spring embedded steering boot 205 gradually increases for some part then constant diameter from the one end. During rotation of the steering shaft either on left hand side or on right hand side, the spring embedded steering boot 205 compresses. Due to the compression of the double side embedded helical spring 206 of the spring embedded steering boot 205, coils of the spring embedded steering boot 205 inserts into the adjacent coils and superimposed in the circular/radial direction to provide enough space for rotation and maintaining the minimum turning radius of the vehicle. Due to the compression, the spring embedded steering boot 205 stores elastic potential energy which is released when rotational force is not applied on the steering shaft. The stored elastic potential energy or returning force of the spring embedded steering boot 205 pushes the rack bar 205 in the original neutral position. The spring embedded steering boot 205 act as an assist mechanism which improves the steering return-ability by forcing the rack bar into its original or neutral position due to stored elastic potential energy in the spring.
[0021] In another embodiment, combination of spring 204 and the spring embedded steering boot 205 helps to store rectilinear elastic potential energy during turning. The stored rectilinear elastic potential energy pushes the rack bar 203 in its original position with great efficiency. The present invention improves the straight stability of the vehicle after turning the vehicle. The present invention also improves the straight running performance along with the steering centering during high speed.
[0022] During turn, as one side spring compresses while other side spring stretches and hence, generate return force in same direction (opposite to applied force direction) and thus, help in steering return-ability. The present invention assists in returning of steering in the gearbox center position without compromising other performance parameters, such as noise.
[0023] The term “vehicle” as used throughout this detailed description and in the claims refers to any moving vehicle that is capable of carrying one or more human occupants and is powered by any form of energy. The term “vehicle” is a motor vehicle which includes, but is not limited to: cars, trucks, vans, minivans, hatchback, sedan, MUVs, and SUVs.
[0024] It will be further appreciated that functions or structures of a plurality of components or steps may be combined into a single component or step, or the functions or structures of one-step or component may be split among plural steps or components. The present invention contemplates all of these combinations. Unless stated otherwise, dimensions and geometries of the various structures depicted herein are not intended to be restrictive of the invention, and other dimensions or geometries are possible. In addition, while a feature of the present invention may have been described in the context of only one of the illustrated embodiments, such feature may be combined with one or more other features of other embodiments, for any given application. It will also be appreciated from the above that the fabrication of the unique structures herein and the operation thereof also constitute methods in accordance with the present invention. The present invention also encompasses intermediate and end products resulting from the practice of the methods herein. The use of “comprising” or “including” also contemplates embodiments that “consist essentially of” or “consist of” the recited feature.
[0025] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/component of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.

,CLAIMS:We claim:
1. An inner ball joint assembly (200) of steering gear box for steering return-ability, the inner ball joint assembly (200) comprising:
a steering shaft connected with a steering wheel, wherein the steering shaft is coupled with rack bar (203) and pinion gear for rotating vehicle;
a ball joint (201) for joining the rack bar (203) and tie rod (202);
a spring embedded steering boot (205) covers the ball joint (201), wherein the spring embedded steering boot (205) stores elastic potential energy during rotation of the steering shaft, the stored elastic potential energy forces the rack bar (203) in axial or rectilinear direction towards original position for straightening the steering wheel.
2. The inner ball joint assembly (200) as claimed in claim 1, wherein spring embedded in the spring embedded steering boot (205) is embedded helical spring.
3. The inner ball joint assembly (200) as claimed in claim 1, wherein the spring embedded steering boot (205) is made of rubber polymer and metal spring with high tensile strength.
4. The inner ball joint assembly (200) as claimed in claim 1, wherein the spring embedded steering boot (205) is connected with the rack housing (208) from one end and with boot bush (207) on the tie rod (202) from the other end.
5. The inner ball joint assembly (200) as claimed in claim 1, wherein winding diameter of the spring embedded steering boot (205) gradually increases for some part then constant diameter from the end connected with boot bush (207) to the other end connected with the rack housing (208).
6. The inner ball joint assembly (200) as claimed in claim 1, wherein winding diameter of the spring embedded steering boot (205) gradually increases from the end connected with boot bush (207) to the other end connected with the rack housing (208).
7. The inner ball joint assembly (200) as claimed in claim 1, wherein coils of the spring embedded steering boot (205) inserts into adjacent coils during compression to provide turning radius to the vehicle.