DESC:TECHNICAL FIELD
[0001] The present subject matter relates in general to a steering assembly for a multi wheeled vehicle, in particular, but not exclusively to an electric power steering assembly for the three-wheeled vehicle.
BACKGROUND
[0002] Most of the multi wheeled vehicles, in particular, three wheeled vehicles are steered by means of a steering actuating member. The most commonly used steering member includes a handle bar or a steering wheel. Such steering actuating member is operatively connected to a steering column either directly or through one or more vibration dampers. Further, the steering column is operatively connected to one or more wheels. In the conventional three wheeled vehicles having one front wheel and two rear wheels, the steering column is connected to the front wheel. In order to turn the front wheel, the driver has to turn the steering column using the steering actuating member. Rotating such a steering assembly having the steering column linked to the front wheel requires a high turning effort from the driver. Also, no support is available to the driver for turning the wheel. The wheel has to be turned only by the force applied by the driver. In order to steer the wheel, the driver has to manually turn the steering actuating member of the vehicle until desired direction of rotation of the wheel is achieved. As a result, more amount of effort is required to turn the wheel at a higher angle of rotation. The link between the front wheel and the steering assembly is cumbersome but still it is preferred because it provides a robust linkage to the steering member and provides direct feedback to the driver while turning the wheel.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] The detailed description is described with reference to an embodiment of a three wheeled vehicle along with the accompanying figures. The same numbers are used throughout the drawings to reference like features and components.
[0004] Figure 1 illustrates a left side view of an exemplary three-wheeled vehicle without the soft top or roof structure, in accordance with an embodiment of the present subject matter.
[0005] Figure 2 illustrates a perspective view of a steering assembly for a vehicle.
[0006] Figure 3 illustrates an exploded view of an electric power steering unit.
[0007] Figure 4 illustrates an exploded view of the steering assembly with the electric power steering unit.
[0008] Figure 5 illustrates a front view of the electric power steering unit of the steering assembly.
[0009] Figure 6 illustrates a flow diagram depicting functionality of the steering system employing the electric power steering unit.
DETAILED DESCRIPTION
[00010] A steering wheel assembly of a vehicle can be rotated for any high angle, of rotation from a left to a right extreme limit, however, a steering actuating member can only be rotated up to a maximum limiting angle until the human hands can comfortably apply the turning force and/or it is limited by the steering limit of the vehicle layout. The limit leads to an undesirable steering feel and can often lead to excess effort to be applied to achieve a desired steering change. Hence, there is a need to improve the steering feel and reduce the human effort while steering of the steering member and yet maintain the same turning angle of the steering member and the same vehicle turning radius. Typically, the torque required to turn the vehicle increases as the front axle load increases. This increase in front axle load results in high steering effort to maneuver the vehicle. Considering the fact that three wheeled vehicles are mainly used for transportation of load and carrying passengers, the driver has to apply great effort to make repeated turns which makes driving very hectic because of the requirement of high steering effort. Therefore, a mechanism to improve drivability of the vehicle and to assist in providing the turning moment required to turn the vehicle is desired.
[00011] In a known art, certain steering support mechanisms are known in four wheeled vehicles such as cars which includes higher capacity electric motors that are directly coupled to the steering column, such mechanisms have higher input requirements as the motors that are employed in the mechanisms are configured to draw lot of power, due to the arrangement of an input shaft and an output shaft being directly connected to the steering column and therefore, more energy has to be provided to the motor to rotate the steering column.
[00012] Such mechanisms are in-line to a steering column or in-line to a rack and pinion mechanism of the four-wheeler. In a rack and pinion-based steering support mechanisms, the rotational motion of a steering wheel is converted into a linear motion by the steering support mechanism which turns the wheels. Such a steering support mechanism involves a steering pinion which locks its teeth on the rack and transforms big rotations of the steering wheel into small turns of the car wheels.
[00013] Further, in known art, there is no reduction mechanism, because at the rack end, the reduction mechanism is already achieved. Also, such systems are expensive and requires a lot of space in the vehicle layout for packaging as well as include a greater number of parts in the assembly. Moreover, in case of multi-wheeled vehicles such as three wheelers, vehicle layout and space constraints does not permit to deploy the existing steering assist systems.
[00014] Further known in the art is a vehicle driven by a column assisted steering support mechanism. Such a steering support mechanism comprises an input shaft and an output shaft disposed along the pivot axis of the steering column. However, such a vehicle poses several problems for the driver. In such a vehicle, since the input shaft and the output shaft are directly connected to the steering column, the steering support mechanism receives undesirable vibrations and road shocks. Such an arrangement makes the steering support mechanism prone to damage and failure.
[00015] Therefore, there is a need to provide simpler, durable, compact and cost-effective assisting mechanism for the vehicle to enhance drivability of the vehicle that is able to solve the above discussed problems and other problems in the art.
[00016] In an aspect, the present invention discloses an improved steering assembly. The steering assembly comprises of a steering member, a steering column and an electric power steering unit (EPS unit). The steering member and the steering column are rotatable about a steering axis (X-X’). The EPS unit is operatively connected to the steering column through a linkage assembly and the EPS unit is disposed laterally offset to the steering axis (X-X’) of the steering assembly.
[00017] In another aspect, the steering assembly comprising a steering member, a steering column and an electric power steering unit (EPS unit). The steering column is disposed inside a head tube. The head tube is a part of the frame of the vehicle and does not rotate with the rotation of the steering column.
[00018] In another aspect, the linkage assembly comprises a first linkage assembly and a second linkage assembly to connect the EPS unit to the steering column wherein the EPS unit is disposed at a lateral offset to the steering column.
[00019] In an aspect, the present invention discloses the steering assembly for a three wheeled vehicle having an EPS unit which is being mounted at a lateral offset to the steering column. The EPS unit is mounted to a bracket of the steering column. The EPS unit includes an input shaft and an output shaft. The input shaft is connected to a steering column through the first linkage assembly which comprises of a gear reduction mechanism. The gear reduction mechanism includes two gears i.e., a primary gear and a secondary gear. The primary gear is installed on the input shaft operatively connected to the secondary gear. The secondary gear is installed on the steering column of the steering assembly. More specifically, the secondary gear is fixedly attached to the steering column. The output shaft of the EPS unit is connected to the steering column through a second linkage assembly. The second linkage assembly comprises a lever mechanism which includes a first lever, second lever and a connecting lever. The first lever is connected to the second lever through the connecting lever. Here, one end of the first lever is connected to the steering column and the other end of the first lever is connected to one end of the connecting lever. On the other hand, one end of the second lever is connected to the output shaft of the EPS unit and the other end of the second lever is connected to the other end of connecting lever. The connection of the EPS unit through the first linkage assembly and the second linkage assembly provides an external mounting of the EPS unit with the steering assembly. The connection through the first linkage assembly and the second linkage assembly ensures that the input shaft and the output shaft do not directly receive road shocks and the vehicle impacts.
[00020] The gear and lever mechanism as described above also provides power assist to the steering assembly, the above described mechanism can be adapted in a conventional vehicle with negligible modifications in an existing steering system and vehicle layout. Therefore, the cost involved in employing the mechanism in the vehicles is negligible. Moreover, due to a gear reduction mechanism and a lever mechanism used to connect the EPS unit with the steering column, the EPS unit used in the present invention does not need heavy motors. Instead, the required power for steering assistance is delivered by a relatively lighter motors connected to the EPS unit.
[00021] The output shaft being connected to the second linkage assembly comprising the lever mechanism, the advantage of the lever mechanism is that effort can be reduced by twenty percent to fifty percent, the rotation of angle of the steering column can be altered by length of the lever mechanism of second linkage assembly at the output shaft.
[00022] . In an embodiment, the angular length of the lever is “r” multiple of theta (?), where “r” being length of the lever assembly and theta (?) is angle of rotation of steering column of vehicle. The lever assembly length “r” and the angle of rotation theta (?) are inversely proportional to each other, the direct relation with “r” multiply theta (?) is an arc length which directly reduces the effort for steering wheel.
[00023] Also, in another embodiment, the head tube is provided with a groove to limit the free flow rotation of the steering column. The groove limits the rotation of the steering column from both sides and prevents free flow rotation of the steering column.
[00024] Further, the first linkage assembly includes the gear reduction mechanism, that aids the driver, for example, if a load of about five kilograms (kgs) is applied to the steering member, the effort that is transferred to the motor is higher, motor provides two kgs effort and lever mechanism, applies about forty percent higher, instead of two kgs, the EPS unit provides three kgs and two hundred grams force onto the steering assembly. The input received from the motor is transferred to the steering assembly by the output shaft connected to the second linkage assembly.
[00025] Further, the steering assembly includes a mounting bracket that is connected to the head tube and configured to support the complete body of the motor and the EPS unit, the mounting bracket is connected to the head tube and includes one or more holes that receive plurality of fastening means for mounting of the EPS unit.
[00026] In an embodiment of the present subject matter, the EPS unit is operatively connected to one or more control units. The control units being electrically operated and controls various electrical and electronic operations of the vehicle.
[00027] According to the gear ratio as in the first linkage assembly of the above steering assembly, as received from the steering member rotation, the EPS unit provides required rotational movement to the steering column and then the same is transferred to the wheels.
[00028] As per the present invention, the packaging of the EPS unit to the steering assembly is compact. The steering assembly including the EPS unit can be disposed below the dashboard and not visible outside. As a result all the elements are beneath the dashboard in the vehicle and thus the layout space is required is less.
[00029] The present subject matter is further described with reference to the accompanying figures. It should be noted that description and figures merely illustrate principles of the present subject matter. Various arrangements may be devised that, although not explicitly described or shown herein, encompass the principles of the present subject matter. Moreover, all statements herein reciting principles, aspects, and examples of the present subject matter, as well as specific examples thereof, are intended to encompass equivalents thereof.
[00030] Figure 1 illustrates a left side view of an exemplary three-wheeled vehicle (100) without the soft top or roof structure, in accordance with an embodiment of the present subject matter. As per one embodiment, the three-wheeled vehicle has a front cowl (106) supporting a windscreen (103). As per one embodiment, the lower portion of the front cowl (106) is connected to a first wheel (108) with a wheel cover (107) disposed in between. A pair of left and right front light assembly (105) disposed on the front cowl (106) of the three-wheeled vehicle (100). A steering actuating member (104) is present behind the front cowl (106) which is used to steer the vehicle (100). As per one embodiment of the present invention, a floor panel (112) is extending from the bottom portion of the front cowl (106) to the rearward direction of the vehicle (100), supported by a vehicle frame structure (116). In one embodiment, the vehicle (100) has a driver’s seat assembly (109) in a front portion of the vehicle (100) and a passenger compartment having at least one passenger seat assembly (113) in a rear portion of the vehicle (100). Further, as per one embodiment, a pair of rear wheels (114) are connected to a swing arm through one or more rear suspension(s). The rear suspension includes a shock absorber and a suspension spring unit (115) mounted to the frame structure (116). The powertrain e.g. an engine (not shown and all the ancillary components are disposed behind the passenger seat assembly (113) in an engine compartment (110).
[00031] Figure 2 illustrates a steering assembly (119) for a vehicle (100) as per the present invention. The steering assembly (119) includes the steering actuating member (104), a steering column (119A-shown in fig 3) and an EPS unit (124). The steering actuating member (104) being partially covered by a steering member cover (104A). The steering assembly (119) is supported on the frame structure (116) of the vehicle (100). The vehicle (100) comprises the frame structure (116), said frame structure (116) includes a main tube (not shown) extending rearwardly from a steering column (119A). The steering assembly (119) is rotatable around a steering axis (X-X’). The steering assembly (119) also include the steering column (119A) and the steering actuating member (104). The steering member cover (104A) of the steering actuating member (104) extends in vehicle lateral direction and travels in direction having a throttle tube (not labelled) on one side of the steering actuating member (104) and a gear shift tube (not labelled) on the other side of the steering member (104). A left and right steering grip (104B) is disposed at the ends of said gear shift tube and said throttle tube respectively at both the ends of the steering actuating member (104). Further, a switch assembly (122) is provided on the steering actuating member (104) for holding plurality of switches, wherein said switch assembly (122) is disposed on both the ends of said steering member cover (104A) and a display member (123) being connected to said steering member cover (104A). The display member (123) includes an instrument cluster, digital or analog or its likes.
[00032] In an embodiment, a head tube (118) and the steering assembly (119) are co-axially disposed on said steering axis (X-X’) of the vehicle (100), and the EPS unit (124) is disposed at a lateral offset to the steering axis (X-X’), being operatively connected to said steering assembly (119) through a linkage assembly (130). The linkage assembly (130) comprises a first linkage assembly (125) and a second linkage assembly (127) to assist a user while steering said vehicle (100). an intermediate coupling means (126) is provided to connect the steering column (119A) and the steering actuating member (104).
[00033] In another additional embodiment, said steering column (119A) includes a first portion (119B), a second portion (120) and a third portion (120A) wherein said first portion (119B) being extending vertically downwards from said steering column (119A) along said steering axis (X-X’), said second portion (120) and said third portion (120A) connects said first portion (119B) and a front wheel (108). The first portion (119B) being connected to said steering actuating member (104) at one end and said EPS unit (124) being disposed laterally offset to said first portion (119B).
[00034] Figure 3 illustrates an exploded of a portion of the present invention showing the EPS unit (124) detached. In an embodiment, the EPS unit (124) comprises the input shaft (124A), the output shaft (124B), a motor (124C). A primary gear (125A) of the first linkage assembly (125) is installed on the input shaft (124A) of the EPS unit (124) and a second lever (127C) of the second linkage assembly (127) is installed on the output shaft (124B) of the EPS unit (124). Further, a secondary gear (125B) is provided on steering column (119A) of the steering assembly (119). Also, a first lever (127A) is provided on the steering column (119A). The first lever (127A) is provided vertically away from the secondary gear (125B). The secondary gear (125B) being part of the first linkage assembly (125) receives the input from the driver as well as input from the first lever (127A) which is part of the second linkage assembly and which transmits input from EPS unit (124) to the first wheel (108). Further, the head tube (118) is provided a groove (129) which limits the rotational motion of the steering column (119A). Also, the first lever (127A) protrudes outward from the groove (129) to connect the connecting lever (127B). Additionally, a connecting lever (127B) being connected between the first lever (127A) and the second lever (127B) by means of plurality of connecting pins (127D) at either side.
[00035] Figure 4 illustrates an exploded view of the steering assembly with an EPS unit along with few peripheral parts for clarity. In an embodiment, the first linkage assembly (125) comprises the primary gear (125A), and the secondary gear (125B). The primary gear (125A) is operatively engaged with said secondary gear (125B). The diameter of said secondary gear (125B) is larger than diameter of said primary gear (125A) to enable a reduced torque input from the driver of the vehicle. The second linkage assembly (127) includes the first lever (127A), the second lever (127C), and the connecting lever (127B), wherein said first lever (127A) being connected to the second lever (127C) through said connecting lever (127B). Also, the steering assembly (119) includes a mounting bracket (128) being connected to the head tube (118) and configured to support the EPS unit (124). The mounting bracket (128) comprises one or more holes that receive plurality of fastening means for mounting of the EPS unit (124). In an embodiment, the first lever (127A) being fixedly connected to the steering column (119A).
[00036] The primary gear (125A) is connected to the EPS unit (124) and the secondary gear (125B) being connected to the steering actuating member (104). The primary gear (125A) and the secondary gear (125B) being operatively engaged to transfer a steering torque input from a driver to said EPS unit (124).
[00037] In an embodiment, one end of the second lever (127C) being connected with said output shaft (124B) of the EPS unit (124). The one end of said second lever (127C) comprises of a second plurality of splines (131 shown in Fig 5). Also, the output shaft (124B) comprises of a first plurality of splines (131). Further, the first plurality of splines (131) of the output shaft (124B) operatively engages with the second plurality of splines on the second lever (127C). The second lever (127C) having an opening which is configured with a second plurality of splines on the internal diameter of said opening.
[00038] In an embodiment, the first plurality of splines (131) provided on the output shaft (124B) of the EPS unit (124) includes a plurality of external splines whereas the second plurality of splines provided on the second lever (127C) includes a plurality of internal splines.
[00039] Figure 5 illustrates a local front view of the present invention showing the EPS unit (124) of the steering assembly (119) and its peripheral parts for brevity. The packaging of the EPS unit (124) is carried out at a lateral offset to the head tube (118) and the steering assembly (119). which enables the steering assembly (119) to be compact in layout and does not occupy additional lateral space.
[00040] Figure 6 illustrates a flow diagram depicting functionality of the steering in the vehicle (100) employing an EPS unit (124). The inputs are provided by the driver to the steering actuating member (104). The steering actuating member (104) is operatively engaged with the intermediate coupling means (126). The input shaft (124A) of the EPS unit (124) receives the input from the steering actuating member (104) and the intermediate coupling means (126) through first linkage assembly (125). Further, an output from the EPS unit (124) is provided to steering column (118) through the second linkage assembly (127). The output shaft (124B) provides required rotational movement, which is transferred to the steering column (118) to assist the driver in steering the vehicle (100) in a comfortable manner with reduced human effort.
[00041] Although the subject matter has been described in considerable detail with reference to certain embodiments thereof, other embodiments are possible. It is to be understood that the appended claims are not necessarily limited to the features described herein. Rather, the features are disclosed as embodiments of the present invention.

LIST OF REFERENCE NUMERALS

100: Vehicle
103: Windscreen
104: Steering Actuating member
104A: Steering member cover
104B: Steering grip
105: Light assembly
106: Front cowl
107: Wheel Cover
108: First wheel
109: Driver Seat assembly
110: Engine compartment
112: Floor Panel
113: Passenger Seat assembly
114: Pair of rear wheels
115: Suspension spring unit
116: Frame structure
118: Head tube
119: Steering assembly
119A: Steering column
121: Suspension system
122: Switch assembly
123: Display member
124: Electric power steering unit (EPS unit)
124A: Input shaft
124B: Output shaft
124C: Motor
125: First linkage assembly
125A: Primary gear
125B: Secondary gear
126: Intermediate Coupling means
127: Second linkage assembly
127A: First lever
127B: Connecting lever
127C: Second lever
127D: Connecting pins
128: Mounting bracket
129: Groove
130: Linkage Assembly
130: First Plurality of Splines
,CLAIMS:I/We claim:
1. A steering assembly (119) for a vehicle (100), said steering assembly (119) comprising:
a steering actuating member (104), said steering actuating member (104) being rotatably supported on a head tube (118) of said vehicle (100);
a steering column (119A), said steering column (119A) being rotatably supported co-axially on said head tube (118) of said vehicle (100); and
an electric power steering (EPS) unit (124),
said steering actuating member (104) and said steering column (119A) being connected to each other and rotatable about a steering axis (X-X’),
wherein, said electric power steering unit (124) being adapted to provide a steering torque assist and being disposed laterally offset to said steering column (119A) of said steering assembly (119).
2. The steering assembly (119) as claimed in claim 1, wherein said electric power steering unit (124) being operatively connected to said steering column (119A) by means of a linkage assembly (130).
3. The steering assembly (119) as claimed in claim 2, wherein said linkage assembly (130) includes a first linkage assembly (125) and a second linkage assembly (127).
4. The steering assembly (119) as claimed in claim 3, wherein said first linkage assembly (125) includes a primary gear (125A), and a secondary gear (125B), said primary gear (125A) being connected to said EPS unit (124) and said secondary gear (125B) being connected to said steering actuating member (104), said primary gear (125A) and said secondary gear (125B) being operatively engaged to transfer a steering torque input from a driver to said EPS unit (124).
5. The steering assembly (119) as claimed in claim 3, wherein said second linkage assembly (127) includes a first lever (127A), a second lever (127C), and a connecting lever (127B), wherein said first lever (127A) being connected to said steering column (119A) and said second lever (127C) being connected to said EPS unit (124), said connecting lever (127B) being operatively connected between said first lever (127A) and said second lever (127C) for transferring steering assisted torque from said EPS unit (124) to said steering column (119A).
6. The steering assembly (119) as claimed in claim 1, wherein said electric power steering unit (124) includes an input shaft (124A) and an output shaft (124B).
7. The steering assembly (119) as claimed in claim 4, wherein said primary gear (125A) being connected to an input shaft (124A) of said EPS unit (124) and said secondary gear (125B) being connected to said steering column (119A).
8. The steering assembly (119) as claimed in claim 4, wherein said EPS unit (124) being connected to said steering actuating member (104) through an intermediate coupling means (126) wherein said intermediate coupling means (126) being rotatably supported on said head tube (118).
9. The steering assembly (119) as claimed in claim 5, wherein said second lever (127C) being coupled to an output shaft (124B) of said EPS unit (124).
10. The steering assembly (119) as claimed in claim 4, wherein diameter of said secondary gear (125B) being greater than diameter of said primary gear (125A).
11. The steering assembly (119) as claimed in claim 5, wherein said first lever (127A) being connected to said second lever (127C) through said connecting lever (127B).
12. The steering assembly (119) as claimed in claim 5, wherein said first lever (127A) being fixedly connected to said steering column (119A).
13. The steering assembly (119) as claimed in claim 5, wherein said second lever (127C) having an opening, said opening being configured with a second plurality of splines on the internal diameter of said opening.
14. The steering assembly (119) as claimed in claim 3 and claim 6, wherein said output shaft (124B) having a first plurality of splines, said plurality of splines being engaged to a second plurality of splines of a second lever (127C) of said second linkage assembly (127).
15.
16. The steering assembly (119) as claimed in claim 1, wherein said electric power steering unit (124) being disposed laterally offset to said head tube (118).
17. The steering assembly (119) as claimed in claim 1, wherein said steering assembly (119) includes a mounting bracket (128), said mounting bracket (128) being connected to said head tube (118) and being configured to support said electric power steering unit (124).
18. The steering assembly (119) as claimed in claim 16, wherein said mounting bracket (128) having one or more holes, said one or more holes being capable of for receiving a plurality of fastening means for mounting of said electric power steering unit (124).
19. The steering assembly (119) as claimed in claim 1 and claim 3, wherein said steering column (119A) being capable of rotating by an angle theta (?) about said steering axis (X-X’), said angle of rotation theta (?) capable of being altered by a length “r” of said second linkage assembly (127).
20. The steering assembly (119) as claimed in claim 18, wherein an angular arc length of said second linkage assembly (127) being “r” multiplied by theta (?).
21. The steering assembly (119) as claimed in claim 18, wherein said length “r” of said second linkage assembly (127) and said angle of rotation theta (?) being inversely proportional to each other.
22. The steering assembly (119) as claimed in claim 1 , wherein said head tube (118) being provided with a groove (129), said groove being adapted to limit rotation of said steering column (119A).
23. The steering assembly (119) as claimed in claim 1, wherein said steering column (119A) includes a first portion (119B), a second portion (120) and a third portion (120A) wherein said first portion (119B) being vertical along said steering axis (X-X’), said second portion (120) and said third portion (120A) connecting said first portion (119) with a front wheel (108) of said vehicle (100).
24. The steering assembly (119) as claimed in claim 22, wherein said first portion (119B) being operatively coupled to said steering actuating member (104) at one end and said electric power steering unit (124) being disposed laterally offset to said first portion (119B).
25. The steering assembly (119) as claimed in claim 1, wherein said electric power steering unit (124) is operatively connected to one or more electronic control units.
26. The steering assembly (119) as claimed in claim 1, wherein said steering assembly (119) being connected to a front wheel (108).
27. The steering assembly (119) as claimed in claim 1, wherein said vehicle (100) includes a three wheeled vehicle.