Claims:CLAIMS
We claim,
1. An anti-dive front fork suspension (1000) for two wheeler motor vehicle comprising
an outer tube (100),
an inner tube (110) telescopically slidable within the outer tube (100),
a seat pipe (150) fixed on its one end (153) to the outer tube (100) by a banjo bolt (130),
a main spring (160) resting on the seat pipe (150) at its one end (163) and on a spacer tube (170) on its other end (167),
the spacer tube (170) further interacts with a fork bolt (180) which is affixed onto the inner tube (110) and characterised by,
the seat pipe (150) having a seat pipe internal chamber (210), the seat pipe (150) having a damping orifice (190) positioned within the seat pipe internal chamber (210), the seat pipe (150) having a stepped portion (220) and, the seat pipe internal chamber (210) having one fluid opening (230) in the banjo bolt (130) and the banjo bolt (130) being further attached to a connector (120) with one connection port.
2. An anti-dive front fork suspension (1000) for two wheeler motor vehicle as claimed in claim 1, wherein a seat pipe internal piston (240) positioned within the seat pipe internal chamber (210) interacts with the stepped portion (220) via a seat pipe internal spring (270) and divides the seat pipe internal chamber (210) into two sub chambers (300, 400) such that the damping orifice (190) is positioned in the sub chamber (300).
3. An anti-dive front fork suspension (1000) for two wheeler motor vehicle comprising
an outer tube (100),
an inner tube (110) telescopically slidable within the outer tube (100),
a seat pipe (150) fixed on its one end (153) to the outer tube (100) by a connecting means (310),
a main spring (160) resting on seat pipe (150) at its one end (163) and on a spacer tube (170) on its other end (167),
the spacer tube (170) further interacts with a fork bolt (180) which is affixed onto the inner tube (110) and characterised by,
the seat pipe (150) having a seat pipe internal chamber (210), the seat pipe (150) having a damping orifice (190) positioned within the seat pipe internal chamber (210), the seat pipe (150) having a stepped portion (220) and, the seat pipe internal chamber (210) having a fluid opening(s) (230) in the connecting means (310) with two connection ports.
4. An anti-dive front fork suspension (1000) for two wheeler motor vehicle as claimed in claim 3, wherein a seat pipe internal piston (240) positioned within the seat pipe internal chamber (210) interacts with the stepped portion (220) via a seat pipe internal spring (270) and divides the seat pipe internal chamber (210) into two sub chambers (300, 400) such that the damping orifice (190) is positioned in the sub chamber (300).
5. An anti-dive front fork suspension (1000) for two wheeler motor vehicle as claimed in claim 1, wherein the connector (120) is further connected to a an anti-lock braking system.
6. An anti-dive front fork suspension (1000) for two wheeler motor vehicle as claimed in claim 1, wherein the connector (120) is further connected to a combined braking system.
7. An anti-dive front fork suspension (1000) for two wheeler motor vehicle as claimed in claim 3, wherein the connecting means (310) is further connected to an anti-lock braking system.
8. An anti-dive front fork suspension (1000) for two wheeler motor vehicle as claimed in claim 3, wherein the connecting means (310) is further connected to a combined braking system.
, Description:FILED OF INVENTION
The invention relates to front fork suspension utilised in two wheeler motor vehicles. It more particularly relates to an anti-dive mechanism that can be provided in front fork suspensions.
BACKGROUND OF THE INVENTION
Two wheeler motor vehicles are known to drop from the front when brakes are applied suddenly. This dropping happens due to weight transfer from the rear axle to the front axle during braking. This phenomenon is commonly identified as diving. Diving in two wheeler motor vehicles isn’t always considered a critical problem requiring a solution to be found and implemented. This problem can be tackled by making the suspension stiffer, but that would then again affect vehicle stability while cornering and braking. The phenomenon of diving specifically affects vehicle control and driver comfort during emergency/sudden braking operations. The suspension setting hence need to change according to situation in order to provide more stability, control and comfort to the rider.
In order to solve this problem, numerous suspensions have been developed to either alter the spring force or damping force during braking operation to resist diving in two wheeler motor vehicle. The anti-dive mechanism altering spring force functions to prevent diving by increasing the loading of the main spring at time of braking. While the anti-dive mechanism altering damping force function by altering damping orifice dimensions during braking. Such mechanisms dealing with diving phenomenon can either be purely mechanical or a combination of electronic and mechanical components.
A low powered two wheeler motor vehicle does not need an anti-dive suspension as the improvements in stability, control and comfort does not justify the added cost. This does not hold true in case of high performance two wheeler motor vehicle where even slight improvement in stability, control and comfort has great overall significance. As of now, cost concerns dictate whether an anti-dive suspension is provided or not. Furthermore, it must also be considered that earlier anti-dive mechanisms which utilised brake torque to jack up front end and pull down the rear end tended to affect the suspension action negatively. They tended to cause the braking torque to spike violently when vehicle hit a bump. The use of such anti-dive mechanisms was hence gradually stopped as little value was added by providing them in two wheeler motor vehicles. Specialised efforts to develop a simple, compact and economical anti-dive front fork suspension were not justified by the increase in profit.
For example JP62191209A discloses one such prior art anti-dive mechanism which resists diving by increasing damping force produced during braking. The suspension unit disclosed is functionally linked to the hydraulic braking system. In the said prior art, shock absorber 10 (as shown in Figure 1) is provided with an anti-dive modulator 9 for improving the suspension unit’s anti-dive performance. The bypass passages 20 and 21 connect the dive modulator 9 with the shock absorber 10. During normal operation, oil flow happens from chamber 18 to chamber 19 though both orifice 17a provided on the piston 17 and also through the bypass passages 20 and 21. During braking, the pressure in the chamber 23 increases which causes the valve member 22 to move and come to rest against the valve seat 28, then the oil flows through orifice 17a only. This allows the suspension unit to resist rapid retraction. It may be observed here that the bypass 20 and 21 and the anti-dive modulator 9 add to the bulk of the suspension unit. The anti-dive modulator 9 and the bypasses (20 and 21) being external components are also vulnerable to damage due to external elements. Furthermore, the space constraints on a two wheeler motor vehicle would not allow such an anti-dive mechanism to be provided on it. The disclosed shock absorber 10 hence cannot be readily utilised in two wheeler vehicles. Furthermore, the size and complexity of the suspension unit also add to its overall cost. Hence, in light of the cited prior art and the limitations cited there is a requirement of an anti-dive front fork suspension which is economical.
It is another objective of the present invention to provide an anti-dive front fork suspension with reduced vulnerability of damage of the anti-dive mechanism.
It is yet another objective of the present invention to provide an anti-dive front fork suspension which houses the anti-dive mechanism within the front fork suspension itself.
It still another objective to provide an anti-dive front fork suspension which has a simple construction with lesser number of components.
One more objective of the present invention is to provide an anti-dive front fork suspension that can be readily utilised in two wheeler motor vehicle.
SUMMARY
An anti-dive front fork suspension is provided having an outer tube, an inner tube telescopically slidable within the outer tube, a seat pipe fixed on its one end to the outer tube by a banjo bolt, a main spring resting on the seat pipe at its one end and on a spacer tube on its other end, the spacer tube further interacting with a fork bolt which is affixed onto the inner tube.
Typically, the seat pipe provided has a seat pipe internal chamber with a damping orifice positioned within the seat pipe internal chamber.
Typically, the seat pipe provided has a stepped portion and a banjo bolt with a fluid opening defining the limits of the seat pipe internal chamber.
Typically, the banjo bolt is connected with a connector provided for attaching hydraulic line(s).
Typically, a seat pipe internal piston is positioned within the seat pipe internal chamber which interacts with the stepped portion via a seat pipe internal spring and divides the seat pipe internal chamber into two sub chambers such that the damping orifice is positioned in the sub chamber.
In the anti-dive front fork provided, upon actuation of brakes, the seat pipe internal piston moves to partially cover the damping orifice. This temporarily increases the damping force produced improving the two wheeler motor vehicles stability, control and comfort during a dive. The anti-dive mechanism being situated within the front fork suspension is of simple and compact construction, with reduced number of components and reduced vulnerability of damage due to external elements. It can be readily utilised in a two wheeler motor vehicles.
BRIEF DESCRIPTION OF DIAGRAMS
Figure 1 illustrates an anti-dive suspension unit according to the prior art.
Figure 2 illustrates the outer view of the anti-dive front fork suspension according to one of the embodiment of the present invention.
Figure 3 illustrates a cross sectional view of the anti-dive front fork suspension according to one of the embodiment of the present invention.
Figure 4 illustrates the magnified cross sectional view of the anti-dive mechanism according to one of the embodiments of the present invention.
Figure 5 illustrates the exploded view of the anti-dive mechanism according to one of the embodiments of the present invention.
Figure 6 illustrates the magnified cross sectional view of the anti-dive mechanism in accordance with second embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The preferred embodiments of anti-dive front fork suspension will now be described in details with reference to accompanying drawings. The preferred embodiments must not be viewed as restricting the scope and ambit of the disclosure.
The Japanese patent JP62191209A discloses a prior art anti-dive mechanism (refer figure 1) which alters damping force produced in the suspension during the braking to allow it to better resist diving. This prior art anti-diving mechanism is hydraulically linked to the motor vehicle’s hydraulic braking system. As indicated in Figure 1, the disclosed shock absorber 10 is provided with an anti-dive modulator 9 for improving the suspension unit’s anti-dive performance. The suspension unit is further provided with bypass passages 20 and 21 to connect the dive modulator 9 with the shock absorber 10. During normal operation of the disclosed suspension unit, the oil flow happens from chamber 18 to chamber 19 though both orifice 17a provided on the piston 17 and also through the anti-dive modulator 9 via the bypass passages 20 and 21. When brakes are applied, the pressure in the chamber 23 increases which causes the valve member 22 to lower and come to rest against the valve seat 28. The oil then flows through orifice 17a only. This hence allows the suspension unit to better resist rapid retraction. It is observable that the prior art anti-dive mechanism is adding bulk to the suspension unit provided. Furthermore, the anti-dive module 9 being an external unit is connected by the bypass passages (20 and 21) to the shock absorber 10. The components of the anti-dive mechanism disclosed are hence vulnerable to damage from external elements. The shock absorber provided with the prior art anti-dive mechanism is hence not readily utilisable in two wheeler motor vehicles. In order to overcome the stated shortcomings of the prior art anti-dive front fork suspension and other stated limitations, an anti-dive front fork suspension (1000) with an anti-dive mechanism is hereon described.
The anti-dive front fork suspension (1000) for two wheeler motor vehicle as per one of the embodiments of the present invention (refer Figure 2) comprises of an outer tube (100), an inner tube (110) telescopically slidable within the outer tube (100). Also, as observable in Figure 2, the anti-dive front-fork suspension (1000) is provided with a banjo bolt (130) (indicated in Figure 3) on its outer tube (100). The banjo bolt (130) has a fluid opening (230) (indicated in Figure 4). The banjo bolt (130) further connects with a connector (120) which in turn enables connection of the anti-dive front fork suspension (1000) with a hydraulic line (120). Other components conventionally forming part of a front fork suspension namely, the outer tube (100), the inner tube (110) telescopically slidable within the outer tube (100), a seat pipe (150) fixed on its one end (153) to the outer tube (100) by a banjo bolt (130), a main spring (160) resting on the seat pipe (150) at its one end (163) and on a spacer tube (170) on its other end (167), the spacer tube (170) further interacts with a fork bolt (180) which is affixed onto the inner tube (110) are respectively indicated in Figure 3.
When the vehicle hits a bump the main spring (160) compresses and absorbs the energy of the impact. As the main spring (160) compresses, the damping fluid flows into the seat pipe (150) through a damping orifice (190). The damping fluid then flows out of the opening at the other end of the seat pipe (150) (the seat pipe (150) being hollow and open at its other end). The flow of damping fluid through the orifice (190) produces the required compression damping. When the vehicle returns to level surface allowing the main spring (160) to expand, the flow of damping fluid is reversed. During compression of the main spring (160), some amount of damping fluid also flows through the gap between the seat pipe (150) and inner tube (110) via a valve (provided in said gap), into a chamber formed between the seat pipe (150) and the inner tube (110). The valve (provided in said gap) present between the inner tube (110) and the seat pipe (150) prevents backflow of the damping fluid through the gap between the seat pipe (150) and the inner tube (110). Therefore when the main spring (160) expands, only the damping orifice (200) allows the damping fluid to flow out of the chamber formed in between the seat pipe (150) and the inner tube (110). The net result is that uncontrolled oscillation of the front fork suspension is avoided. The functioning of other components (like the rebound spring, seals and washers) is similar to those provided in a conventional front forks as known in the art. Figure 3 further indicates the cross sectional view of the anti-dive mechanism as per the first embodiment of the anti-dive front fork (1000) within the dotted portion (500).
The magnified and exploded view of the anti-dive mechanism as per the current invention indicated by dotted portion (500) in Figure 3, are shown in Figure 4 & 5 respectively. The anti-dive mechanism provided comprises of the seat pipe (150) having the seat pipe internal chamber (210), the seat pipe internal piston (240), the seat pipe internal spring (270), the banjo bolt (130) having the fluid opening (230) and the connector (120) with one connection port provided on it. The limits of the seat pipe internal chamber (210) provided within the seat pipe (150) are formed by the stepped portion (220) and the lower portion of the banjo bolt (130) provided on the outer tube (100) which are both observable in the magnified view of the dotted portion (500) (shown in Figure 4). A damping orifice (190) is positioned within the seat pipe internal chamber (210).
The damping orifice (200) is provided on the seat pipe (150) close to the end of the seat pipe (150) on which the main spring (160) rests. The seat pipe internal chamber (210) has a fluid opening (230) through the banjo bolt (130). The fluid opening (230) connects with the hydraulic line (140) (indicated in Figure 2) via a connector (120) having one connection port. The seat pipe internal piston (240) is provided within the seat pipe internal chamber (210). The seat pipe internal piston (240) is provided with an O-ring (250) in the groove (260). Providing the seat pipe internal piston (240) hence seals off and creates two separate sub chambers (300 and 400) within the seat pipe internal chamber (240), wherein the damping orifice (190) is situated in the sub chamber (300). The seat pipe internal piston (240) interacts with the stepped portion (220) via a seat pipe internal spring (270).
Upon operation of a front wheel brake actuator (290) (observable in Figure 2) by the rider, the brake hydraulic fluid is displaced from the front wheel brake master cylinder (280) (present but not observable in Figure 2) through the hydraulic line (140) and into the sub chamber (400) via the connector (120) and the fluid opening (230) provided in the banjo bolt (130). The seat pipe internal piston (240) hence experiences a force which causes it to compress the seat pipe internal spring (270) and retract towards the stepped portion (220). The seat pipe internal piston (240) while retracting covers the damping orifice (190) partially causing the damping force produced to increase, thus controlling the dive. When the rider ceases to operate the front wheel brake actuator (290) the displaced brake hydraulic fluid returns to the front wheel brake master cylinder (280) via the fluid path formed by the fluid opening (230), the connector (120) and the hydraulic line (140). With the force no longer acting over the seat pipe internal piston (240), the seat pipe internal piston (240) returns to its original position under the action of the seat pipe internal spring (270). This causes the damping orifice (190) to be uncovered. The change in damping setting hence lasts as long as the rider continues to operate the front wheel brake actuator. The bush (137) prevents the seat pipe internal piston (240) from moving further upwards. This insulates the braking system from any pressure oscillations due to vehicle hitting a big road surface irregularity.
The connector (120) with one connection port can be connected by a hydraulic line to a combined braking system. The operation of a rear brake actuator would then cause brake hydraulic fluid to flow into the sub chamber (400). The manner of functioning of the anti-dive mechanism provided in the anti-dive front fork suspension (1000) would therefore remain the same. Similarly, the connector (120) can also be connected to a hydraulic line from an anti-lock braking system without altering the manner of functioning of the anti-dive mechanism provided in the anti-dive front fork suspension (1000).
The anti-dive mechanism can also be provided with a connecting means (310) (indicated in Figure 6) with two openings for connecting it with two hydraulic lines, in place of banjo bolt (130) which has just one opening for connecting it with only one hydraulic line (140). This would allow the anti-dive front fork (1000) to be connected with both front and rear wheel brake hydraulic circuits. The functioning of the anti-dive mechanism provided with connecting means (310) would otherwise be the same as that of anti-dive mechanism provided with a banjo bolt (130). The brake hydraulic fluid flowing into the sub-chamber (400) upon application of either the front or rear wheel brakes or both would cause the seat pipe internal piston (240), the seat pipe internal spring (270) and the damping orifice (190) present in the sub-chamber (300) to effect change in damping force in the same manner as already described in case of anti-dive mechanism provided with banjo bolt (130). The flow path for return of brake hydraulic fluid upon cessation of braking operation would be from the sub chamber (400) to the connecting means (310) and then to the respective brake hydraulic circuits.
The connecting means (310) having two connection ports can be connected to hydraulic lines from front brake and rear brake hydraulic circuit respectively. One hydraulic line of the two connected to the connecting means (310) can also come from a combined braking system. The connecting means (310) may also be connected to an anti-lock braking system via its connecting ports. In any case, the brake hydraulic fluid would flow into sub chamber (400). The manner of function of the anti-dive mechanism provided in the anti-dive front fork suspension (1000) would remain the same.
The components of anti-dive mechanism are shielded from the external elements by the inner and outer tube (110 and 100). This reduces their probability of getting damaged. The simple and compact construction of the anti-dive mechanism allows it to be incorporated within any conventional front fork with minimum structural alterations. The anti-dive front fork (1000) is hence very economical to provide in any two wheeler motor vehicle. This further allows the anti-dive front fork (1000) to be readily utilised in any two wheeler motor vehicle.
While it is stated that the anti-dive front fork (1000) is hydraulically connected via a hydraulic line(s) to front wheel circuit or rear wheel circuit or both. The stated pathway can be altered to allow the sub chamber (400) to be hydraulically connected with an Anti-lock Braking System (ABS) hydraulic circuit or a Combined Braking System (CBS) hydraulic circuit as well. Any modification carried out to the anti-dive front fork (1000) to allow such hydraulic connection to be made lie within the scope of the invention.
List of reference numbers
100………..Outer Tube
110………..Inner Tube
120………..Connector
130………..Banjo Bolt
133………...Washer
137………...Bush
140………..Hydraulic Line
150………..Seat Pipe
153………...One End of Seat Pipe
160…………Main Spring
163…………One End of Main Spring
167…………Other End of Main Spring
170………….Spacer Tube
180………….Fork Bolt
190………….Damping Orifice
200………….Damping Orifice
210………….Seat Pipe Internal Chamber
220…………..Stepped Portion
230…………..Fluid Opening