WO2023012833A1 - Ackermann steering system based on single bilateral rotary steering-torque transmission arm using elliptic bevel gear sets - Google Patents
Ackermann steering system based on single bilateral rotary steering-torque transmission arm using elliptic bevel gear sets Download PDFInfo
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- WO2023012833A1 WO2023012833A1 PCT/IN2022/050712 IN2022050712W WO2023012833A1 WO 2023012833 A1 WO2023012833 A1 WO 2023012833A1 IN 2022050712 W IN2022050712 W IN 2022050712W WO 2023012833 A1 WO2023012833 A1 WO 2023012833A1
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- Prior art keywords
- bevel gear
- steering
- wheel
- central
- steering shaft
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- 230000005540 biological transmission Effects 0.000 title claims abstract description 80
- 230000002146 bilateral effect Effects 0.000 title claims abstract description 7
- 230000007246 mechanism Effects 0.000 claims abstract description 31
- 238000009434 installation Methods 0.000 claims abstract description 8
- 230000009471 action Effects 0.000 claims abstract description 5
- 244000309464 bull Species 0.000 claims description 36
- 230000007935 neutral effect Effects 0.000 claims description 23
- 230000007423 decrease Effects 0.000 claims description 13
- 239000000725 suspension Substances 0.000 claims description 6
- 125000000174 L-prolyl group Chemical group [H]N1C([H])([H])C([H])([H])C([H])([H])[C@@]1([H])C(*)=O 0.000 claims description 5
- 238000013016 damping Methods 0.000 claims description 2
- 230000003247 decreasing effect Effects 0.000 claims 1
- 238000010586 diagram Methods 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 3
- 230000003134 recirculating effect Effects 0.000 description 3
- 238000005461 lubrication Methods 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 230000008901 benefit Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D3/00—Steering gears
- B62D3/02—Steering gears mechanical
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D7/00—Steering linkage; Stub axles or their mountings
- B62D7/06—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins
- B62D7/08—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins the pivotal axes being situated in a single plane transverse to the longitudinal centre line of the vehicle
- B62D7/09—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins the pivotal axes being situated in a single plane transverse to the longitudinal centre line of the vehicle characterised by means varying the ratio between the steering angles of the steered wheels
Definitions
- Mechanism comprises multiple complex linkages which are difficult to manufacture and maintain. Components including recirculating ball screws, ball linkages, track rods, tie rods etc require frequent lubrication with lubrication being challenging exercise each time.
- This steering demonstrates all the critical steering features. It is important that while cornering the wheels can be steer turned by unequal angles as well as reverted back to neutral steer position in predictable fashion. Steering of vehicle according to Ackermann geometry require that the inner front wheel steer angle is greater than outer front wheel steer angle with their difference higher for higher steer angle in a special way. Steering of vehicle according to anti- Ackermann geometry require that the outer front wheel steer angle is greater than inner front wheel steer angle with their difference higher for higher steer angle in a special way. Steering system according to this invention can fulfill such a purpose by making use of continuous transmission ratio gradient of conjugate pair of elliptic bevel gear around the neutral conjugate contact point (NCCP).
- NCCP neutral conjugate contact point
- Neutral conjugate contact point in this patent document, is referred to that meshing point at which transmission ratio is equal to one.
- transmission ratio is maximum (approximately equal to M/m where M is major axis length and m is minor axis length) when vertex of driving gear meshes with covertex of driven gear and is minimum (approximately equal to m/M) when covertex of driving gear meshes with vertex of driven gear.
- Transmission ratio continuously increases when meshing point moves from vertex to covertex of driven gear.
- Neutral conjugate contact point (NCCP) lies between covertex and vertex of driven gear as well as driving gear.
- NCP Neutral conjugate contact point
- first type contact point on driven gear lies in the quadrant in which transmission ratio increases for clockwise rotation of meshing point
- second type contact point on driven gear lies in the quadrant in which transmission ratio decreases for clockwise rotation of meshing point.
- conjugate pair of second order elliptic bevel gears there are two Neutral conjugate contact point (NCCP) of first type separated by angular distance of 180 degree and two Neutral conjugate contact point (NCCP) of second type separated by angular distance of 180 degree.
- Pivot point in this case is foci and transmission ratio is maximum for only one meshing point and minimum only for one meshing point with pivot points with minimum and maximum transmission ratio
- Neutral conjugate contact point (NCCP) of second type is chosen as meshing point for conjugate pair of elliptic bevel gear installed on right wheel and Neutral conjugate contact point (NCCP) of first type is chosen as meshing point for conjugate pair of elliptic bevel gear installed on left wheel.
- This steering system can rotate the wheels by 360 degree due to which it can be used to maneuver the vehicle out of difficult terrain conditions or parking space.
- Steering system is integrated to the chassis (and its components do not project out of the main chassis) of the vehicle due to which it is more robust against alignment problems and therefore require less frequent maintenance.
- This steering system may lead to reduction of weight and hence increase in fuel efficiency of the vehicle.
- This steering system also allows more space for installation of other systems like suspension system, cooling system. Additionally, components are concealed from external conditions like dirt, mud and therefore require less frequent maintenance.
- Steering system comprises bevel gears, ball bearings, as main components which are in use in multiple equipments and do not require specialized manufacturing process. Spare parts inventory for this steering system is far less challenging.
- This steering system has special advantage in situation of configuration for vehicle maneuvering at high speed.
- For configuring the vehicle for various types of anti- Ackermann condition one only needs to rotate the left and right shafts by 180 degree whereas in order to replace Ackermann trapezoid mechanism by Davis steering mechanism one needs to change almost all the components which includes bar linkages, rack-pinion gears, bearings, recirculating ball screws etc.
- FIG. 1 Front view of Steering system with a single bilateral rotary steer-torque transmission arm with elliptic bevel gear sets configured according to Ackermann condition showing gear sets in neutral steer position.
- FIG. 2 Steering system configured according to Ackermann condition showing elliptic bevel gear sets after steering rightward direction by 45 degree.
- FIG. 3 Steering system configured according to Ackermann condition showing elliptic bevel gear sets after steering leftward direction by 45 degree.
- FIG. 4 Steering system with a single bilateral rotary steer-torque transmission arm with elliptic bevel gear sets configured according to anti-Ackermann condition showing gear sets in neutral steer position.
- FIG. 5 Schematic diagram of rightward steering of Steering system.
- FIG. 6 Schematic diagram of leftward steering of Steering system.
- Steering system based on single bilateral rotary steering-torque transmission arm using elliptic bevel gear sets for four wheelers or reverse tricycles which 1) can be optimally configured to provide close approximation to proAckermann for steer rotation of inner wheel by an angle less than or equal to 90 degree or antiAckermann condition for steer rotation of outer wheel by an angle less than or equal to 90 degree; and 2) can rotate wheels by 360 degree; and comprises central steering shaft (CSS), left steering shaft (LSS), right steering shaft (RSS), left steering-torque transmission arm (LST) and right steering-torque transmission arm (RST), steer support mechanism (SSM), one circular bevel gear set as central steering mechanism (CSM), two identical conjugate pairs of elliptic bevel gears as left wheel bevel gear set (LBS) and right wheel bevel gear set (RBS), with their vertically oriented bevel-gears mounted on central steering shaft (CSS), left steering shaft (
- Central steering shaft is a vertically oriented rod coplanar to, parallel to and located between left steering shaft (LSS) and right steering shaft (RSS) and connected at its upper end to handle;
- Central steering shaft (CSS), Left steering shaft (LSS) and right steering shaft (RSS) are appropriately rotatably coaxially housed in tubes via ball bearing which in turn is fixedly attached to the chassis of the vehicle;
- left steering-torque transmission arm (LST) is horizontally oriented rod located between central steering shaft (CSS) and left wheel steering shaft (LSS) connecting central steering mechanism (CSM) to left wheel bevel gear set (LBS);
- right steering-torque transmission arm (RST) is horizontally oriented rod located between central steering shaft (CSS) and right wheel steering shaft (RSS) connecting central steering mechanism (CSM) to right wheel bevel gear set (RBS);
- left steering-torque transmission arm (LST) and right steering-torque transmission arm (RST) acts as medium to transmit steering torque of central steering shaft to left steering shaft and right steering shaft via rotation action;
- Elliptic bevel gears used in steering system as shown in the diagrams are elliptic bevel gears of second order;
- Elliptic bevel of other orders like first order can also used, pitch curve of which is shown in Fig. 7, Fig. 8 and Fig. 9.
- CSM Central steering mechanism
- central steering mechanism consists of 1) a pair of coaxially parallel vertically oriented identical circular bevel gears, as central top bevel gear (CB1) and central bottom bevel gear (CB2) coaxially mounted on the central steering shaft (CSS) with their teeth side facing each other and 2) a pair of coaxially parallel horizontally oriented identical circular bevel gears with their teeth side facing each other, as, central left bevel gear (CPI) and central right bevel gear (CP2) wherein central left bevel gear (CPI) located on left side of central steering shaft is coaxially fixedly mounted on the right end of left steering-torque transmission arm (LST); central right bevel gear (CP2) located on left side of central steering shaft is coaxially fixedly mounted on the left end of right steering-torque transmission arm (RST);
- CSM central steering mechanism
- central bottom bevel gear (CB2) located at lower side of central right bevel gear (CP2) is coaxially rotatably mounted on central steering shaft (CSS) via roller ball bearing whereas central top bevel gear (CB1) located at upper side of central right bevel gear (CP2) is coaxially fixedly mounted on central steering shaft (CSS); central left bevel gear (CPI) and central right bevel gear (CP2) are meshingly engaged with vertically oriented bevel gears central top bevel gear (CB1) and central bottom bevel gear (CB2); central top bevel gear (CB1) is driving bevel gear while central left bevel gear (CPI), central right bevel gear (CP2) and central bottom bevel gear (CB2) are driven bevel gears; gear ratio of central top bevel gear (CB1) (and central bottom bevel gear (CB2)) with central left bevel gear (CPI) (and central right bevel gear (CP2)) is equal to required steering ratio of the steering system.
- LBS Left wheel bevel gear set
- LBS Left wheel bevel gear set
- LB Left wheel bull bevel gear
- LP Left wheel pinion bevel gear
- Left wheel bull bevel gear (LB) is driven gear and Left wheel pinion bevel gear (LP) is driving gear;
- Left wheel bull bevel gear a vertically oriented bevel gear is coaxially mounted at its appropriate point on the left steering shaft (LSS) with its teeth facing upward direction;
- Left wheel pinion bevel gear (LP) horizontally oriented bevel located on the right side of the Left steering shaft (LSS) towards upper side of Left wheel bull bevel gear (LB) with teeth facing towards left steering shaft (LSS) is mounted on left end of left steering-torque transmission arm (LST) in such a way that Left wheel bull bevel gear (LB) meshingly engaged with Left wheel pinion bevel gear (LP);
- Left wheel pinion bevel gear is an elliptic bevel gear, of appropriate size chosen according to requirement of Ackermann or Anti- Ackermann steering, coaxially fixedly mounted on the left end of left steering-torque transmission arm (LST) such that its teeth meshes with left wheel bull bevel gear (LB);
- Pivot point of Left wheel bull bevel gear (LB) and Left wheel pinion bevel gear (LP) are such that sum of instantaneous cone angle (with respect to every meshing point) is right angle, which in case of second order elliptic bevel gear can be centrode of pitch curve.
- conjugate pair of elliptic bevel gears consists of two identical elliptic bevel gears as Right wheel bull bevel gear (RB) and Right wheel pinion bevel gear (RP) wherein
- Right wheel bull bevel gear (RB) is driven gear and Right wheel pinion bevel gear (RP) is driving gear;
- Right wheel bull bevel gear (RB) a vertically oriented bevel gear is coaxially mounted at its appropriate point on the Right steering shaft (RSS) with its teeth facing upward direction;
- Right wheel pinion bevel gear (RP) horizontally oriented bevel located on the right side of the Right steering shaft (RSS) towards upper side of Right wheel bull bevel gear (RB) with teeth facing towards Right steering shaft (RSS) is mounted on Right end of Right steeringtorque transmission arm (RST) in such a way that Right wheel bull bevel gear (RB) meshingly engaged with Right wheel pinion bevel gear (RP);
- Right wheel pinion bevel gear (RP) and Right wheel bull bevel gear (RB) are identical to Left wheel pinion bevel gear (LP) and Left wheel bull bevel gear (LB), respectively;
- Pivot point of Right wheel bull bevel gear (RB) and Right wheel pinion bevel gear (RP) are such that sum of instantaneous cone angle (with respect to every meshing point) is right angle, which in case of second order elliptic bevel gear can be centrode of pitch curve.
- Meshing point of the left wheel bevel gear set and right wheel bevel gear set is at the point 1) where transmission ratio between driving and driven gear is one, 2) while vehicle is steering left side, transmission ratio of driving to driven gear of left wheel gear set increases and of right wheel gear set decreases and 3) while steering right side transmission ratio of driving to driven gear of left wheel gear set decreases and of right wheel gear set increases; left wheel bevel gear set (LBS) and right wheel bevel gear set (RBS) are mirror image with respect to vertical longitudinal zero plane of the vehicle.
- LBS left wheel bevel gear set
- RBS right wheel bevel gear set
- Meshing point of the left wheel bevel gear set and right wheel bevel gear set is at the point 1. where transmission ratio between driving and driven gear is one, 2) while steering left side transmission ratio of driving to driven gear of left wheel gear set decreases and of right wheel gear set increases and 3) while steering right side transmission ratio of driving to driven gear of left wheel gear set increases and of right wheel gear set decreases; left wheel bevel gear set (LBS) and right wheel bevel gear set (RBS) are mirror image with respect to vertical longitudinal zero plane of the vehicle.
- LBS left wheel bevel gear set
- RBS right wheel bevel gear set
- Steer support mechanism a mechanism with of help which steer system is connected to the vehicle and steering-torque transmission arms can be kept aligned and allowed to rotate whenever required, comprises two tubes, as right steer transmission head tube (RTH), left steer transmission head tube (LTH), coaxially rotatably housing right steering-torque transmission arm (RST), left steering-torque transmission arm (LST), respectively via ball bearings.
- RTH right steer transmission head tube
- LTH left steer transmission head tube
- RST right steering-torque transmission arm
- LST left steering-torque transmission arm
- suspension system plays a vital role during steering of any four wheeler.
- steering system (1) have the provision to provide suspension system (SPN) by allowing right steering shaft (RSS) and left steering shaft (LSS) to be Shock-damping system with axle of the front wheel being attached to outer protecting cover and axle eye attached to fixed link via ball bearing.
- SPN suspension system
- central top bull bevel gear rotates in clockwise direction which in turn via central left pinion bevel gear and left wheel pinion bevel gear rotates left wheel bull gear in clockwise direction and via central right pinion bevel gear and right wheel pinion bevel gear rotates right wheel bull
- SUBSTITUTE SHEETS (RULE 26) gear in clockwise direction and therefore results in steering the wheels in leftward direction. If the elliptic bevel gears installed according to Pro- Ackermann transmission ratio of left wheel bevel gear set will continuously increase and transmission ratio of right wheel bevel gear set will continuously decrease. If the elliptic bevel gears installed according to Anti- Ackermann condition, transmission ratio of left wheel bevel gear set will continuously decrease and transmission ratio of right wheel bevel gear set will continuously increase.
- Each elliptic gear can accommodate left wheel and right wheel elliptic bevel gears sets with each elliptic gear having minor axis as 9 inch and major axis as 11.7 inch. In case requirement is only to rotate the wheel by -45 degree to +45 degree, only sector portion of elliptic bevel gear may be installed.
Abstract
This patent discloses a single bilateral rotary-steering-torque transmission arm based light weight steering system for four wheelers, which can be optimally configured to provide close approximation to Ackermann condition. Ackermann (anti-Ackermann) condition requires wheels to turn by unequal steer angles for inner and outer wheel. Therefore left hand side mechanism and right hand side mechanism turns the wheel asymmetrically and reverses their role while steering other side. This steering mechanism accomplishes bifurcation mechanism of steering action in to two different modes of steering at each of the two front wheels by employing special assembly of two sets of elliptic bevel gears. Monotonic increase in transmission ratio of conjugate pair of elliptic bevel gears with respect to meshing point with unity transmission ratio in appropriate region of elliptic bevel gears is utilized to achieve pro-Ackermann condition (or anti-Ackermann condition depending on the installation).
Description
Description
Title of Invention: Ackermann Steering System based on Single Bilateral Rotary Steering- Torque Transmission Arm using Elliptic Bevel Gear Sets
Field of Invention
[01] Steering system for four wheelers satisfying pro/anti Ackermann condition.
Background of Invention
[02] Steering mechanism of automobiles (four wheelers or reverse-trikes) having two front wheels need to satisfy Ackermann condition during low to medium speed drive and antiAckermann conditions during high speed drive. Meeting Ackermann condition is much more required for very low valued wheelbase to track width ratio.
Technical Problem
[03] According to current mechanical Ackermann steering system, which is based on trapezoidal mechanism, rotation motion is converted into linear (reciprocating) motion which is then converted back to steering rotation at the wheel kingpin. Wheels can be turned by maximum of 45 degree.
[04] Mechanism comprises multiple complex linkages which are difficult to manufacture and maintain. Components including recirculating ball screws, ball linkages, track rods, tie rods etc require frequent lubrication with lubrication being challenging exercise each time.
[05] Spare parts inventory is difficult to manage as each component require special manufacturing process. Components including recirculating ball screws, ball linkages etc are uncommon for other industrial or transportation machinery equipment. With each different model these components come in different sizes due to which even two year old models become unserviceable or irreparable. It becomes difficult to find original equipment manufacturers for components with less frequent application.
[06] Portion of Trapezoidal mechanism (with seven bar linkages) for Ackermann steering mechanism or Davis steering mechanism are located away from main chassis and therefore prone to misalignments while driving on uneven roads.
Summary of Invention
SUBSTITUTE SHEETS (RULE 26)
[07] Rotation steering action at the handle is transmitted as steering action on the wheel through rotation motion of steer-torque transmission arm and is not converted into planar translation motion as intermediate phase. Therefore steering arms via head tubes can be integrated with the frame of vehicle.
[08] This steering demonstrates all the critical steering features. It is important that while cornering the wheels can be steer turned by unequal angles as well as reverted back to neutral steer position in predictable fashion. Steering of vehicle according to Ackermann geometry require that the inner front wheel steer angle is greater than outer front wheel steer angle with their difference higher for higher steer angle in a special way. Steering of vehicle according to anti- Ackermann geometry require that the outer front wheel steer angle is greater than inner front wheel steer angle with their difference higher for higher steer angle in a special way. Steering system according to this invention can fulfill such a purpose by making use of continuous transmission ratio gradient of conjugate pair of elliptic bevel gear around the neutral conjugate contact point (NCCP). Neutral conjugate contact point (NCCP), in this patent document, is referred to that meshing point at which transmission ratio is equal to one. In case of conjugate pair of second order elliptic bevel gears transmission ratio is maximum (approximately equal to M/m where M is major axis length and m is minor axis length) when vertex of driving gear meshes with covertex of driven gear and is minimum (approximately equal to m/M) when covertex of driving gear meshes with vertex of driven gear. Transmission ratio continuously increases when meshing point moves from vertex to covertex of driven gear. Neutral conjugate contact point (NCCP) lies between covertex and vertex of driven gear as well as driving gear. In case of conjugate pair of second order elliptic bevel gears there are two types of Neutral conjugate contact point (NCCP). For first type contact point on driven gear lies in the quadrant in which transmission ratio increases for clockwise rotation of meshing point and for second type contact point on driven gear lies in the quadrant in which transmission ratio decreases for clockwise rotation of meshing point. In case of conjugate pair of second order elliptic bevel gears, there are two Neutral conjugate contact point (NCCP) of first type separated by angular distance of 180 degree and two Neutral conjugate contact point (NCCP) of second type separated by angular distance of 180 degree.
In case of conjugate pair of first order elliptic bevel gears case is different. Pivot point in this case is foci and transmission ratio is maximum for only one meshing point and minimum only for one meshing point with pivot points with minimum and maximum transmission ratio
2
SUBSTITUTE SHEETS (RULE 26)
separated by an angular distance of 180 degree. In case of conjugate pair of first order elliptic bevel gears there is only one Neutral conjugate contact point (NCCP) of first type and only one Neutral conjugate contact point (NCCP) of second type. For pro-Ackermann installation of conjugate pairs of elliptic bevel gears, Neutral conjugate contact point (NCCP) of first type is chosen as meshing point for conjugate pair of elliptic bevel gear installed on right wheel and Neutral conjugate contact point (NCCP) of second type is chosen as meshing point for conjugate pair of elliptic bevel gear installed on left wheel. For anti- Ackermann installation of conjugate pairs of elliptic bevel gears, Neutral conjugate contact point (NCCP) of second type is chosen as meshing point for conjugate pair of elliptic bevel gear installed on right wheel and Neutral conjugate contact point (NCCP) of first type is chosen as meshing point for conjugate pair of elliptic bevel gear installed on left wheel. This steering system can rotate the wheels by 360 degree due to which it can be used to maneuver the vehicle out of difficult terrain conditions or parking space.
[09] Steering system, according to this invention is integrated to the chassis (and its components do not project out of the main chassis) of the vehicle due to which it is more robust against alignment problems and therefore require less frequent maintenance. This steering system may lead to reduction of weight and hence increase in fuel efficiency of the vehicle. This steering system also allows more space for installation of other systems like suspension system, cooling system. Additionally, components are concealed from external conditions like dirt, mud and therefore require less frequent maintenance.
[10] Steering system comprises bevel gears, ball bearings, as main components which are in use in multiple equipments and do not require specialized manufacturing process. Spare parts inventory for this steering system is far less challenging.
[11] This steering system has special advantage in situation of configuration for vehicle maneuvering at high speed. For configuring the vehicle for various types of anti- Ackermann condition, one only needs to rotate the left and right shafts by 180 degree whereas in order to replace Ackermann trapezoid mechanism by Davis steering mechanism one needs to change almost all the components which includes bar linkages, rack-pinion gears, bearings, recirculating ball screws etc.
Brief Description of Drawings
SUBSTITUTE SHEETS (RULE 26)
[12] Fig. 1 Front view of Steering system with a single bilateral rotary steer-torque transmission arm with elliptic bevel gear sets configured according to Ackermann condition showing gear sets in neutral steer position.
[13] Fig. 2 Steering system configured according to Ackermann condition showing elliptic bevel gear sets after steering rightward direction by 45 degree.
[14] Fig. 3 Steering system configured according to Ackermann condition showing elliptic bevel gear sets after steering leftward direction by 45 degree.
[15] Fig. 4 Steering system with a single bilateral rotary steer-torque transmission arm with elliptic bevel gear sets configured according to anti-Ackermann condition showing gear sets in neutral steer position.
[16] Fig. 5 Schematic diagram of rightward steering of Steering system.
[17] Fig. 6 Schematic diagram of leftward steering of Steering system.
[18] Fig. 7, Fig. 8 and Fig. 9 Pitch curve of elliptic bevel curve from various view points.
Description of Embodiments
[19] As shown in Fig. l, Fig. 2 and Fig. 3, Steering system based on single bilateral rotary steering-torque transmission arm using elliptic bevel gear sets for four wheelers or reverse tricycles, which 1) can be optimally configured to provide close approximation to proAckermann for steer rotation of inner wheel by an angle less than or equal to 90 degree or antiAckermann condition for steer rotation of outer wheel by an angle less than or equal to 90 degree; and 2) can rotate wheels by 360 degree; and comprises central steering shaft (CSS), left steering shaft (LSS), right steering shaft (RSS), left steering-torque transmission arm (LST) and right steering-torque transmission arm (RST), steer support mechanism (SSM), one circular bevel gear set as central steering mechanism (CSM), two identical conjugate pairs of elliptic bevel gears as left wheel bevel gear set (LBS) and right wheel bevel gear set (RBS), with their vertically oriented bevel-gears mounted on central steering shaft (CSS), left steering shaft (LSS), right steering shaft (RSS) respectively, horizontally oriented gears mounted on left steering-torque transmission arm (LST) and right steering-torque transmission arm (RST) wherein
SUBSTITUTE SHEETS (RULE 26)
Left steering shaft (LSS) and right steering shaft (RSS) are parallel vertically oriented rods connected at their lower end to the inward end of axle of left and right wheel respectively;
Central steering shaft (CSS) is a vertically oriented rod coplanar to, parallel to and located between left steering shaft (LSS) and right steering shaft (RSS) and connected at its upper end to handle;
Central steering shaft (CSS), Left steering shaft (LSS) and right steering shaft (RSS) are appropriately rotatably coaxially housed in tubes via ball bearing which in turn is fixedly attached to the chassis of the vehicle; left steering-torque transmission arm (LST), is horizontally oriented rod located between central steering shaft (CSS) and left wheel steering shaft (LSS) connecting central steering mechanism (CSM) to left wheel bevel gear set (LBS); right steering-torque transmission arm (RST), is horizontally oriented rod located between central steering shaft (CSS) and right wheel steering shaft (RSS) connecting central steering mechanism (CSM) to right wheel bevel gear set (RBS); left steering-torque transmission arm (LST) and right steering-torque transmission arm (RST) acts as medium to transmit steering torque of central steering shaft to left steering shaft and right steering shaft via rotation action;
Elliptic bevel gears used in steering system as shown in the diagrams are elliptic bevel gears of second order;
Elliptic bevel of other orders like first order can also used, pitch curve of which is shown in Fig. 7, Fig. 8 and Fig. 9.
Central steering mechanism (CSM)
[20] As shown in Fig. l, Fig. 2 and Fig. 3, central steering mechanism (CSM), consists of 1) a pair of coaxially parallel vertically oriented identical circular bevel gears, as central top bevel gear (CB1) and central bottom bevel gear (CB2) coaxially mounted on the central steering shaft (CSS) with their teeth side facing each other and 2) a pair of coaxially parallel horizontally oriented identical circular bevel gears with their teeth side facing each other, as, central left bevel gear (CPI) and central right bevel gear (CP2) wherein central left bevel gear (CPI) located on left side of central steering shaft is coaxially fixedly mounted on the right end of left steering-torque transmission arm (LST); central right bevel gear (CP2) located on left side of central steering shaft is coaxially fixedly mounted on the left end of right steering-torque transmission arm (RST);
5
SUBSTITUTE SHEETS (RULE 26)
central bottom bevel gear (CB2), located at lower side of central right bevel gear (CP2) is coaxially rotatably mounted on central steering shaft (CSS) via roller ball bearing whereas central top bevel gear (CB1) located at upper side of central right bevel gear (CP2) is coaxially fixedly mounted on central steering shaft (CSS); central left bevel gear (CPI) and central right bevel gear (CP2) are meshingly engaged with vertically oriented bevel gears central top bevel gear (CB1) and central bottom bevel gear (CB2); central top bevel gear (CB1) is driving bevel gear while central left bevel gear (CPI), central right bevel gear (CP2) and central bottom bevel gear (CB2) are driven bevel gears; gear ratio of central top bevel gear (CB1) (and central bottom bevel gear (CB2)) with central left bevel gear (CPI) (and central right bevel gear (CP2)) is equal to required steering ratio of the steering system.
Left wheel bevel gear set (LBS)
[21] As shown in Fig. l, Fig. 2 and Fig. 3, conjugate pair of elliptic bevel gears, Left wheel bevel gear set (LBS), consists of two identical elliptic bevel gears as Left wheel bull bevel gear (LB) and Left wheel pinion bevel gear (LP) wherein
Left wheel bull bevel gear (LB) is driven gear and Left wheel pinion bevel gear (LP) is driving gear;
Left wheel bull bevel gear (LB) a vertically oriented bevel gear is coaxially mounted at its appropriate point on the left steering shaft (LSS) with its teeth facing upward direction;
Left wheel pinion bevel gear (LP) horizontally oriented bevel located on the right side of the Left steering shaft (LSS) towards upper side of Left wheel bull bevel gear (LB) with teeth facing towards left steering shaft (LSS) is mounted on left end of left steering-torque transmission arm (LST) in such a way that Left wheel bull bevel gear (LB) meshingly engaged with Left wheel pinion bevel gear (LP);
Left wheel pinion bevel gear (LP) is an elliptic bevel gear, of appropriate size chosen according to requirement of Ackermann or Anti- Ackermann steering, coaxially fixedly mounted on the left end of left steering-torque transmission arm (LST) such that its teeth meshes with left wheel bull bevel gear (LB);
Pivot point of Left wheel bull bevel gear (LB) and Left wheel pinion bevel gear (LP) are such that sum of instantaneous cone angle (with respect to every meshing point) is right angle, which in case of second order elliptic bevel gear can be centrode of pitch curve.
6
SUBSTITUTE SHEETS (RULE 26)
Right wheel bevel gear set (RBS)
[22] As shown in Fig. l, Fig. 2 and Fig. 3, conjugate pair of elliptic bevel gears, Right wheel bevel gear set (RBS), consists of two identical elliptic bevel gears as Right wheel bull bevel gear (RB) and Right wheel pinion bevel gear (RP) wherein
Right wheel bull bevel gear (RB) is driven gear and Right wheel pinion bevel gear (RP) is driving gear;
Right wheel bull bevel gear (RB) a vertically oriented bevel gear is coaxially mounted at its appropriate point on the Right steering shaft (RSS) with its teeth facing upward direction;
Right wheel pinion bevel gear (RP) horizontally oriented bevel located on the right side of the Right steering shaft (RSS) towards upper side of Right wheel bull bevel gear (RB) with teeth facing towards Right steering shaft (RSS) is mounted on Right end of Right steeringtorque transmission arm (RST) in such a way that Right wheel bull bevel gear (RB) meshingly engaged with Right wheel pinion bevel gear (RP);
Right wheel pinion bevel gear (RP) and Right wheel bull bevel gear (RB) are identical to Left wheel pinion bevel gear (LP) and Left wheel bull bevel gear (LB), respectively;
Pivot point of Right wheel bull bevel gear (RB) and Right wheel pinion bevel gear (RP) are such that sum of instantaneous cone angle (with respect to every meshing point) is right angle, which in case of second order elliptic bevel gear can be centrode of pitch curve.
Pro-Ackermann Installation
[23] In order that steering system steer the vehicle according to close approximation to ProAckermann steering geometry till inner wheel steering angle, denoted by Ai, is less than 90 degree, gear sets need to satisfy additional conditions according to which at neutral position, as shown in Fig. 1,
Meshing point of the left wheel bevel gear set and right wheel bevel gear set is at the point 1) where transmission ratio between driving and driven gear is one, 2) while vehicle is steering left side, transmission ratio of driving to driven gear of left wheel gear set increases and of right wheel gear set decreases and 3) while steering right side transmission ratio of driving to driven gear of left wheel gear set decreases and of right wheel gear set increases; left wheel bevel gear set (LBS) and right wheel bevel gear set (RBS) are mirror image with respect to vertical longitudinal zero plane of the vehicle.
Anti-Ackermann Installation
7
SUBSTITUTE SHEETS (RULE 26)
[24] In order that steering system steer the vehicle according to close approximation to AntiAckermann steering geometry till outer wheel steering angle, denoted by Ao, is less than 90 degree, gear sets need to satisfy additional conditions according to which at neutral position, as shown in Fig. 4,
Meshing point of the left wheel bevel gear set and right wheel bevel gear set is at the point 1. where transmission ratio between driving and driven gear is one, 2) while steering left side transmission ratio of driving to driven gear of left wheel gear set decreases and of right wheel gear set increases and 3) while steering right side transmission ratio of driving to driven gear of left wheel gear set increases and of right wheel gear set decreases; left wheel bevel gear set (LBS) and right wheel bevel gear set (RBS) are mirror image with respect to vertical longitudinal zero plane of the vehicle.
Steer Support Mechanism
[25] As shown in Fig. l, Fig. 2 and Fig. 3, Steer support mechanism (SSM), a mechanism with of help which steer system is connected to the vehicle and steering-torque transmission arms can be kept aligned and allowed to rotate whenever required, comprises two tubes, as right steer transmission head tube (RTH), left steer transmission head tube (LTH), coaxially rotatably housing right steering-torque transmission arm (RST), left steering-torque transmission arm (LST), respectively via ball bearings.
Suspension System
[26] Since all the four wheels of a four wheeler vehicle must roll on the ground to provide uniform steering geometry, suspension system plays a vital role during steering of any four wheeler.
[27] As shown in Fig. l, Fig. 2 and Fig. 3, steering system (1) according to this invention have the provision to provide suspension system (SPN) by allowing right steering shaft (RSS) and left steering shaft (LSS) to be Shock-damping system with axle of the front wheel being attached to outer protecting cover and axle eye attached to fixed link via ball bearing.
Steering operation
[28] As shown via schematic diagrams Fig. 5 when handle is rotated in clockwise direction, central top bull bevel gear rotates in clockwise direction which in turn via central left pinion bevel gear and left wheel pinion bevel gear rotates left wheel bull gear in clockwise direction and via central right pinion bevel gear and right wheel pinion bevel gear rotates right wheel bull
8
SUBSTITUTE SHEETS (RULE 26)
gear in clockwise direction and therefore results in steering the wheels in leftward direction. If the elliptic bevel gears installed according to Pro- Ackermann transmission ratio of left wheel bevel gear set will continuously increase and transmission ratio of right wheel bevel gear set will continuously decrease. If the elliptic bevel gears installed according to Anti- Ackermann condition, transmission ratio of left wheel bevel gear set will continuously decrease and transmission ratio of right wheel bevel gear set will continuously increase.
[29] As shown via schematic diagrams Fig. 6 when handle is rotated in anti-clockwise direction, central top bull bevel gear rotates in anti-clockwise direction which in turn via central left pinion bevel gear and left wheel pinion bevel gear rotates left wheel bull gear in anti-clockwise direction and via central right pinion bevel gear and right wheel pinion bevel gear rotates right wheel bull gear in anti-clockwise direction and therefore results in steering the wheels in rightward direction. If the elliptic bevel gears installed according to Pro-Ackermann transmission ratio of left wheel bevel gear set will continuously decrease and transmission ratio of right wheel bevel gear set will continuously increase. If the elliptic bevel gears installed according to Anti- Ackermann condition, transmission ratio of left wheel bevel gear set will continuously increase and transmission ratio of right wheel bevel gear set will continuously decrease.
Feasibility of Steering Mechanism
[30] For elliptic gear, with aspect ratio (ratio of length of major axis to minor axis) equal to 1.3, maximum transmission ratio is 1.3 and minimum transmission ratio is 1/1.3. Therefore on rotation of wheels by 45 degree ratio of transmission ratio of elliptic gear sets at inner wheel (which is left wheel during leftward steering and right wheel during rightward steering) to the transmission ratio of outer wheel (which is right wheel during leftward steering and left wheel during rightward steering) continuously rises to 1.69. Therefore elliptic bevel gear sets with each elliptic gear having aspect ratio is sufficient to achieve steering geometry as close approximation to Pro/ Anti Ackerman condition. Four wheeler vehicles can accommodate left wheel and right wheel elliptic bevel gears sets with each elliptic gear having minor axis as 9 inch and major axis as 11.7 inch. In case requirement is only to rotate the wheel by -45 degree to +45 degree, only sector portion of elliptic bevel gear may be installed.
SUBSTITUTE SHEETS (RULE 26)
Claims
[Claim 1] Steering system based on single bilateral rotary steering-torque transmission arm using elliptic bevel gear sets for four wheelers which
1) according to first installation of elliptic bevel gear sets can provide steering to the vehicle according to close approximation to pro-Ackermann geometry for steer angle of inner wheel less than 90 degree and according to second installation of elliptic bevel gear sets can provide steering to the vehicle according to close approximation to antiAckermann geometry for steer angle of outer wheel less than 90 degree;
2) fulfills critical steering requirements according to which while vehicle is cornering the wheels can be steer turned by unequal angles (in a special way as required by either proAckermann or anti- Ackermann condition) as well as reverted back to neutral steer position in predictable fashion;
3) fulfills critical steering requirements by choosing meshing point of each conjugate pairs of elliptic bevel gears, at neutral steer position of front wheels, as appropriate neutral conjugate contact point, where neutral conjugate contact point is a meshing point of conjugate pairs of elliptic bevel gears at which transmission ratio is one, in order to make use of monotonic increasing/decreasing transmission ratio of conjugate pairs of elliptic bevel gears at their meshing point at their respective appropriate region;
4) can rotate wheels by 360 degree; comprises central steering shaft, left steering shaft, right steering shaft, left steering-torque transmission arm and right steering-torque transmission arm, steer support mechanism, one circular bevel gear sets as central steering mechanism, two identical conjugate pairs of elliptic bevel gears as Left wheel bevel gear set and Right wheel bevel gear set, with their vertically oriented bevel-gears mounted on central steering shaft, left steering shaft, right steering shaft respectively, horizontally oriented gears mounted on left steering-torque transmission arm and right steering-torque transmission arm wherein
Left steering shaft and right steering shaft are parallel vertically oriented rods connected at their lower end to the inward end of axle of left and right wheel respectively;
Central steering shaft is a vertically oriented rod coplanar to, parallel to and located between left steering shaft and right steering shaft and connected at its upper end to handle;
Central steering shaft, Left steering shaft and right steering shaft are appropriately rotatably coaxially housed in tubes via ball bearing which in turn is fixedly attached to the chassis of the vehicle; left steering-torque transmission arm, is horizontally oriented rod located between central steering shaft and left wheel steering shaft connecting central steering mechanism to left wheel bevel gear set ; right steering-torque transmission arm, is horizontally oriented rod located between central steering shaft and right wheel steering shaft connecting central steering mechanism to right wheel bevel gear set; left steering-torque transmission arm and right steering-torque transmission arm acts as medium to transmit steering torque of central steering shaft to left steering shaft and right steering shaft via rotation action; asymmetry of elliptic arc with respect to extremity points of equi-conjugate diameters as bifurcation mechanism to convert rotation of steering arms as left side and right side nonparallel (Pro/ Anti Ackermann) steering mechanism;
Elliptic bevel gears used are, preferably but not restricted to, of first and second order, and have provision to install suspension system.
[Claim 2] Central steering mechanism, claimed in claim 1, consists of 1) a pair of coaxially parallel vertically oriented identical circular bevel gears, as central top bevel gear and central bottom bevel gear coaxially mounted on the central steering shaft with their teeth side facing each other and 2) a pair of coaxially parallel horizontally oriented identical circular bevel gears with their teeth side facing each other, as, central left bevel gear and central right bevel gear wherein central left bevel gear located on left side of central steering shaft is coaxially fixedly mounted on the right end of left steering-torque transmission arm; central right bevel gear located on left side of central steering shaft is coaxially fixedly mounted on the left end of right steering-torque transmission arm; central bottom bevel gear, located at lower side of central right bevel gear is coaxially rotatably mounted on central steering shaft via roller ball bearing whereas central top bevel gear located at upper side of central right bevel gear is coaxially fixedly mounted on central steering shaft; central left bevel gear and central right bevel gear are meshingly engaged with vertically oriented bevel gears central top bevel gear and central bottom bevel gear;
central top bevel gear is driving bevel gear while central left bevel gear, central right bevel gear and central bottom bevel gear are driven bevel gears; gear ratio of central top bevel gear (and central bottom bevel gear) with central left bevel gear (and central right bevel gear) is equal to required steering ratio of the steering system.
[Claim 3] Conjugate pair of elliptic bevel gears, Left wheel bevel gear set, claimed in Claim 1, is a consists of two identical elliptic bevel gears as Left wheel bull bevel gear and Left wheel pinion bevel gear wherein
Left wheel bull bevel gear is driven gear and Left wheel pinion bevel gear is driving gear;
Left wheel bull bevel gear a vertically oriented bevel gear is coaxially mounted at its pivot point on the left steering shaft with its teeth facing upward direction;
Left wheel pinion bevel gear horizontally oriented bevel located on the right side of the Left steering shaft towards upper side of Left wheel bull bevel gear with teeth facing towards left steering shaft is mounted on left end of left steering-torque transmission arm in such a way that Left wheel bull bevel gear meshingly engaged with Left wheel pinion bevel gear ;
Left wheel pinion bevel gear is an elliptic bevel gear, of appropriate size chosen according to requirement of Pro- Ackermann or Anti- Ackermann steering, coaxially fixedly mounted on the left end of left steering-torque transmission arm such that its teeth meshes with left wheel bull bevel gear;
Pivot point of Left wheel bull bevel gear and Left wheel pinion bevel gear are such that sum of instantaneous cone angle (with respect to every meshing point) is right angle, which in case of second order elliptic bevel gear can be centrode of pitch curve.
[Claim 4] Conjugate pair of elliptic bevel gear, Right wheel bevel gear set, claimed in [Claim 1], consists of a pair of two identical elliptic bevel gears as Right wheel bull bevel gear and Right wheel pinion bevel gear wherein
Right wheel bull bevel gear is driven gear and Right wheel pinion bevel gear is driving gear;
Right wheel bull bevel gear a vertically oriented bevel gear is coaxially mounted at its pivot point on the Right steering shaft with its teeth facing upward direction;
Right wheel pinion bevel gear horizontally oriented bevel located on the right side of the Right steering shaft towards upper side of Right wheel bull bevel gear with teeth facing towards Right steering shaft is mounted on Right end of Right steering-torque transmission arm in such a way that Right wheel bull bevel gear meshingly engaged with Right wheel pinion bevel gear ;
Right wheel pinion bevel gear and Right wheel bull bevel gear are identical to Left wheel pinion bevel gear and Left wheel bull bevel gear, respectively;
Pivot point of right wheel bull bevel gear and Right wheel pinion bevel gear are such that sum of instantaneous cone angle (with respect to every meshing point) is right angle which in case of second order elliptic Bevel gear can be centrode of pitch curve and in case of first order of elliptic bevel gear can be one of the foci of the pitch curve.
[Claim 5] In order that steering system steer the vehicle according to close approximation to Pro-Ackermann steering geometry till inner wheel steering angle, denoted by Ai, is less than 90°, conjugate pairs of elliptic bevel gears need to satisfy additional conditions according to which at neutral position
Meshing point of the Left wheel bevel gear set and Right wheel bevel gear set is at the point 1) where transmission ratio between driving and driven gear is one, 2) while steering left side transmission ratio of driving to driven gear of left wheel gear set increases and of right wheel gear set decreases and 3) while steering right side transmission ratio of driving to driven gear of left wheel gear set decreases and of right wheel gear set increases; left wheel gear set and right wheel gear set are mirror image with respect to vertical longitudinal zero plane of the vehicle.
[Claim 6] In order that steering system steer the vehicle according to close approximation to Anti- Ackermann steering geometry till outer wheel steering angle, denoted by Ao, is less than 90°, elliptic bevel gear sets need to satisfy additional conditions according to which at neutral position
Meshing point of the left wheel bevel gear set and right wheel bevel gear set is at the point 1) where transmission ratio between driving and driven gear is one, 2) while steering left side transmission ratio of driving to driven gear of left wheel gear set decreases and of right wheel gear set increases and 3) while steering right side transmission ratio of driving to driven gear of left wheel gear set increases and of right wheel gear set decreases; left wheel gear set and right wheel gear set are mirror image with respect to vertical longitudinal zero plane of the vehicle.
[Claim 7] Steer support mechanism, claimed in claim 1, a mechanism with of help which steering system is connected to the vehicle and steering-torque transmission arms can be kept aligned and allowed to rotate whenever required, comprises two tubes, as right steer transmission head tube, left steer transmission head tube, coaxially rotatably housing right
steering-torque transmission arm, left steering-torque transmission arm, respectively via ball bearings.
[Claim 8] Steering system according to this invention have the provision to provide suspension system, as claimed in Claim 1, by allowing right steering shaft and left steering shaft to be Shock-damping system with axle of the front wheel being attached to outer protecting cover and axle eye attached to fixed link via ball bearing.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IN202121035458 | 2021-08-06 | ||
| IN202121035458 | 2021-08-06 |
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| WO2023012833A1 true WO2023012833A1 (en) | 2023-02-09 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/IN2022/050712 WO2023012833A1 (en) | 2021-08-06 | 2022-08-07 | Ackermann steering system based on single bilateral rotary steering-torque transmission arm using elliptic bevel gear sets |
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| Country | Link |
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| WO (1) | WO2023012833A1 (en) |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201844836U (en) * | 2010-10-15 | 2011-05-25 | 合肥赛迅机电科技有限公司 | South pointing chariot |
-
2022
- 2022-08-07 WO PCT/IN2022/050712 patent/WO2023012833A1/en unknown
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201844836U (en) * | 2010-10-15 | 2011-05-25 | 合肥赛迅机电科技有限公司 | South pointing chariot |
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