DESC:Field of the invention

The present invention relates to a damping mechanism in vehicles and more specifically, to a hydropneumatic front fork for two-wheelers.

Background of the invention

It is vital to keep contact between the vehicle tires and ground intact while driving; especially in situations when the terrain is imperfect with bumps or dips. A vehicle suspension system that uses spring and damper arrangement not only maintains the ground contact but also safeguards the driver and vehicle parts from the impact between the vehicle tires and road imperfections.

The damping mechanism known presently consists of a piston, a spindle taper, and an inner tube assembly, which comprises a spacer oil lock, a guide spring, and a seat spring. The hollow piston allows the formation of an oil chamber within it. The head of the piston has a groove in which sits a piston ring. The assembly also has an arrangement to prevent the oil from flowing over its outer surface and allow it along its inner diameter. Damping forces are created by the forced movement of oil through controlled orifices in the stem of the piston. A combination of oil flow and extension of the main spring creates compression stroke and rebound damping. The diameter and the entry chamfer control the rate of oil flow and nature of flow respectively and hence control damping value.

However, the tuning of damping forces for different velocities, weight of the suspension, spring noise, and preload adjustment are some of the issues in the conventional design.

Accordingly, there exists a need for a lightweight, noise-free damping mechanism with preload adjustment that can be configured for tuning of the damping forces for different velocities.
Objects of the invention

An object of the present invention is to provide a hydropneumatic front fork in which pneumatic spring force is generated by deploying an air spring in one or more variable gas chambers.

Another object of the present invention is to provide a hydropneumatic front fork in which a gas chamber is provided in the inner tube of the front suspension so as to increase the oil pressure to avoid cavitation.

Another object of the present invention is to provide flexibility to vary the ride height of a two-wheeler front suspension by deploying one or more gas chambers.

Yet another object of the present invention is to deploy one or more gas chambers with capacities such that combinations thereof result in an infinitely variable rated gas spring in the hydropneumatic front fork.

Yet another object of the present invention is to adjust the pressure of the gas in one or more gas chambers so as to tune the pneumatic spring force as per the ride height.

Yet another object of the present invention is to provide an electronically controlled ride height adjustment in a hydropneumatic front fork.

Yet another object of the present invention is to provide an electronically monitored and controlled air spring for the hydropneumatic front fork.

Yet another object of the present invention is to provide a tunable damping mechanism for the front suspension of a two-wheeler with the aid of a double-acting piston and compression/rebound valve pack.

Yet another object of the present invention is to provide a hydropneumatic front fork that is able to furnish a bottom-less feel by the compression of a bump stop.

Summary of the invention

Accordingly, the present invention provides a hydropneumatic front fork (hereinafter, “the front fork”) for vehicles, more particularly for two-wheelers. The front fork comprises an inner tube telescopically connected to an outer tube. The inner tube includes a piston rod assembled inside therein. A floating piston is inserted inside the inner tube. The floating piston divides the inner tube into a first gas chamber and an oil chamber. A double-acting piston fitted with a rebound and compression valve pack is assembled with the piston rod. A second gas chamber is filled with pressurized gas for achieving targeted spring force for solo condition. A third gas chamber filled with pressurized gas of different pressure is used with the second gas chamber to achieve the spring rate/force for dual conditions. A bump stop provides compression during an end of a compression stroke.

The front fork also includes a pneumatic preload adjuster to vary ride height of the two-wheeler. The pneumatic preload adjuster includes an adjuster screw and a spacer. The adjuster screw is assembled with a bolt cap and capable of rotating in a clockwise/anti clockwise direction to adjust the ride height. The bolt cap includes a sealant assembled thereon to prevent the air leakage from the first gas chamber. The spacer is joined with the adjuster screw using a counter sunk screw and a sealant O-ring. The spacer moves in a forward/backward direction with rotation of the adjuster screw.

In accordance with the present invention, the front fork is operably connected to an integrated electronic control system. The integrated electronic control system includes a sensor, an electronic control unit, a bi-directional pump and a conditioning unit. The sensor is assembled on the front fork for continuously monitoring the pressure and temperature of the second gas chamber and sending feedbacks. The electronic control unit is configured to receive and store user inputs as set values for the pressure and temperature of the air in the second gas chamber, to compare the set values with the feedback received from the sensor, and to calculate the difference therebetween. The bi-directional pump receives signal from the electronic control unit to adjust the temperature and pressure of the air and supply to the second gas chamber. The conditioning unit includes a heater and cooler. The conditioning unit regulates the temperature of an output from the bi-directional pump.

Brief description of the drawings

The objects and advantages of the present invention will become apparent when the disclosure is read in conjunction with the following figures, wherein
Figure 1 illustrates a schematic diagram of a hydropneumatic front fork with a single-rated air spring, in accordance with an embodiment of the present invention;

Figure 2 represents a schematic diagram of a hydropneumatic front fork with a dual-rated air spring, in accordance with another embodiment of the present invention;

Figure 3 shows the hydropneumatic front fork with a pneumatic preload adjuster, in accordance with the present invention;

Figures 4-5 illustrate working of the pneumatic preload adjuster, in accordance with the present invention; and

Figure 6 shows a schematic diagram of the hydropneumatic front fork with an integrated electronic control system, in accordance with the present invention.

It should be appreciated by those skilled in the art that any schematic diagrams herein represent conceptual views of illustrative systems embodying the principles of the present invention.

Detailed description of the invention

The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiment.

The present invention provides a hydropneumatic front fork for two-wheelers. The hydropneumatic front fork of the present invention is well applicable for telescopic and inverted front fork. The hydropneumatic front fork of the present invention is provided with a pneumatic preload adjuster to vary the ride height of the two wheeled motorcycle. The hydropneumatic front fork of the present invention is also implemented with an integrated electronic control system.

Throughout this application, with respect to all reasonable derivatives of such terms, and unless otherwise specified (and/or unless the particular context clearly dictates otherwise), each usage of:
“a” or “an” is meant to read as “at least one.”
“the” is meant to be read as “the at least one.”

References in the specification to “one embodiment” or “an embodiment” mean that a particular feature, structure, characteristic, or function described in connection with the embodiment is included in at least one embodiment. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.

Hereinafter, embodiments will be described in detail. For clarity of the description, known constructions and functions will be omitted.

The terms, “hydropneumatic front fork”, “front fork”, “fork”, “assembly”, and “damper” are used interchangeably throughout the document.

The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures. These reference numbers are shown in brackets in the following description.

Referring to figure 1, a hydropneumatic front fork (100) (hereinafter, “the front fork (100)”) with a single-rated air spring in accordance with the present invention is shown. The front fork (100) comprises an inner tube (103) telescopically connected to an outer tube (114). The inner tube (103) with a cavity acts as a damper body. The inner tube (103) includes a piston rod (112) assembled inside therein. A double-acting piston fitted with a rebound and compression valve pack (107) is assembled with the piston rod (112) and a recoil bumper (109). A damper cap (111) is connected at a bottom end of the inner tube (103). The connection of the damper cap (111) to the inner tube (103) can be by a threaded connection. The damper cap (111) comprises a rod guide (108), an oil seal (110), and a sealant. The damper cap (111) and the rod guide (108) are formed in a single part. A floating piston (104) is inserted inside the inner tube (103) and divides the cavity in the inner tube (103) into a first gas chamber (102) and an oil chamber (105). The chambers confine fluids such as oil and/or gas. In an embodiment, the floating piston (104) and the double-acting piston (111) are made from plastic or aluminum. Alternatively, the double-acting piston (111) can be a banded piston. In one of the exemplary embodiments of the present invention, the piston is provided with a plurality of orifices for the movement of the oil during compression and rebound cycles by lifting respective compression and rebound valve packs.
The top portion of the inner tube (103) is fitted with a bolt cap with an air-filling shaft (101) for sealing the assembly. The bolt cap with an air-filling shaft (101) is used to fill the gas inside the front fork (100). An air-filling shaft (115) is used to fill air inside a second gas chamber (113). The first gas chamber (102) is filled with pressurized gas to avoid cavitation in the front fork (100). A bump stop (116) with a bump stop seater (117) is assembled in such a way as to hold the piston rod (112). A mud seal (106) is configured on the outer tube (114) to protect surface of the inner tube (103).

Figure 2 shows a hydropneumatic front fork (100) (hereinafter, “front fork (100)”) implemented with a dual-rated air spring in accordance with another embodiment of the present invention. In this one embodiment, the second gas chamber (113) and a third gas chamber (118) are used to produce the infinitely variable rated pneumatic spring force in the suspension. The third gas chamber (118) is incorporated in the front fork (100) for dual spring action. In an embodiment, an initial pressure in the first gas chamber (102) is maintained in the range of 20-30 bar and based on the air load requirements, the same can be tuned. The ratio of the pressures in the second gas chamber (113) to that in the third gas chamber (118) is maintained as 1:4.

In accordance with the present invention, in the single rated spring as shown in figure 1, only second gas chamber (113) is used through which the targeted spring force is achieved. In the dual rated spring as shown in figure 2, two gas chambers (113 and 118) are used. The third gas chamber (118) is filled with high pressurized gas compared to the second gas chamber (113). Particularly, the compressed gas/air with different pressure is filled in the second gas chamber (113) and the third gas chamber (118) respectively for dual rated spring. The second gas chamber (113) is used to achieve spring rate for solo condition and combination of the chambers (113, 118) is used to achieve the spring rate for dual conditions. Specifically, the single and dual rated springs are used to maintain the ride height of the vehicles during solo (rider alone) and dual (rider and pillion) load conditions.

As shown in figures 3-5, the front fork (100) also includes a pneumatic preload adjuster (200) or ride height adjustment arrangement (hereinafter, “the preload adjuster (200)”) to vary the ride height of the two wheeler/two wheeled motorcycle. The preload adjuster (200) includes an adjuster screw (124) assembled with a bolt cap (125) by means of thread interface. The adjuster screw (124) is joined with a spacer (127) using a counter sunk screw (130) and a sealant O-ring (129). The gas volume is sealed between the floating piston (104) and the spacer (127) with help of a sealant O-ring (128). A gas filling valve consists of a valve case (119), an elastomer (123), a sealant (120) and a gas filling screw (121) is assembled on the adjuster screw (124) by means of a thread interface and sealed by a sealant ring (122). The bolt cap (125) includes a sealant (126) assembled thereon to prevent the air leakage from the first gas chamber (102).

As shown in figures 4-5, the ride height of the vehicle is adjusted by rotating the adjuster screw (124) in a clock-wise direction. When the adjuster screw is (124) rotated, the spacer (127) leads forward due to the thread interface between the bolt cap (125) and the adjuster screw (124). When the spacer (127) starts to move, which compresses the gas volume in the first gas chamber (102) and pressure increases relatively. The forward movement of the adjuster screw (124) is constrained by contact between the adjuster screw (124) and the bolt cap (125). The preload is reduced by rotating the adjuster screw (124) in an anti-clockwise direction. The backward movement of the adjuster screw (124) is restricted by a surface contact between the spacer (127) and the bolt cap (125).

Referring again to figures 1-2, in an operation, when the front wheel of the vehicle hits any irregularity on the driving terrain, the outer tube (114) slides upward, because of which the piston (104) moves through the oil, and the inner tube (103) starts to compress the air in the second gas chamber (113). This compression results in the generation of pneumatic spring force. As shown in figure 2, the movement of the piston causes the compression of air in the second gas chamber (113) and the third gas chamber (118). The compression damping forces are created by the forced movement of oil through the double-acting piston with the compression valve pack (107). The volume enclosed by the double-acting piston and the damper cap (hereinafter referred to as “extension chamber”, not shown in the diagram) provides a path to the oil once it flows through the compression holes of the piston. The pressurized gas in the first gas chamber (102) provides an air load to the suspension system. The bump stop (116) provides compression during the end of the compression stroke to avoid bottoming in the front fork (100).

Following the compression stroke, the air inside the second gas chamber (113) and the third gas chamber (118) begins to expand. This causes the outer tube (114) to slide downwards. This in turn results in the movement of the piston assembly from the top toward the bottom. Subsequent to this, the oil flows into the volume enclosed by the floating piston and the double-acting piston (hereinafter referred to as “compression chamber”, not shown in the diagram). The oil is forced through the double-acting piston with the rebound valve pack (107) and rebound damping is created. The pressurized gas in the first gas chamber (102) provides an initial load for the rebound stroke of the front fork (100). The recoil bumper (109) is used to avoid the topping of the front fork (100).

In an implementation according an embodiment of the present invention, the front fork (100) is operably connected with an integrated electronic control system (300) (hereinafter, the system (300)”) as shown in figure 6. The system (300) includes a sensor (301), an electronic control unit (302) (hereinafter, “ECU (302)”), a bi-directional pump (303) and a conditioning unit (304).

The sensor (301) is assembled on the front fork (100) and operably connected to the ECU (302). In an embodiment, the sensor (301) is a temperature and pressure sensor. The sensor (301) continuously monitors the pressure and temperature of the second gas chamber (113) and sends feedbacks to the ECU (302). The ECU (302) and the bi-directional pump (303) are used for automatic adjustment of the temperature and pressure of the second gas chamber (113) based on the sensor feedback. The ECU (302) is configured to receive and store user inputs as set values for the pressure and temperature of the air in the second gas chamber (113), to compare the set values with those (feedback) received from the sensor (301), and to calculate the difference therebetween. Accordingly, the ECU (302) sends the signal corresponding to the difference to the bi-directional pump (303), to adjust the temperature and pressure of the air and supply to the second gas chamber (113). The conditioning unit (304) consisting of a heater and cooler is used to regulate the temperature of an output from the bi-directional pump (303) before sending it to the second gas chamber (113) and stored for actions.

Referring again to figures 1, 2 and 6, in an operation of the system (300), a user needs to feed a required system temperature and pressure to the ECU (302) during an initial setting of the hydro pneumatic suspension. Once the user fed the inputs, the bi-directional pump (303) pumps the ambient air with targeted volume and pressure. The sensor (301) assembled on front fork (100) continuously monitors the pressure and temperature of the second gas chamber (113) and sends feedbacks to the ECU (302). The ECU (302) compares the sensor feedback with a pre-defined input stored during the initial setting. If the sensor feedback matches with the system setting, then no action is triggered by the ECU (302). If the sensor feedback doesn’t match with the system setting, then the ECU (302) sends signal to the bi-directional pump (303) and the conditioning unit (304) to maintain the temperature and pressure in the second gas chamber (113).

Advantages of the invention

1. The present invention eliminates spring noise and provides a lighter weight fork design.
2. In the front fork (100), tuning of damping forces for different velocities is made easy with the use of a double-acting piston.
3. In the front fork (100), tuning for different settings of spring stiffness is easily achieved by simply adjusting the air pressure.
4. The front fork (100) facilitates achievement of consistency in damping with the gas-charged damper assembly.
5. The front fork (100) allows easy ride height adjustment by varying the gas chamber pressure.
6. The front fork (100) facilitates electronically controlled ride height adjustment with the help of the ECU (302) and the bi-directional pump (303).
7. The front fork (100) facilitates electronically monitoring and controlling of the air spring.

The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the scope of the present invention. ,CLAIMS:We claim:

1. A hydropneumatic front fork (100) for a two-wheeler, the hydropneumatic front fork (100) comprising:
an inner tube (103) telescopically connected to an outer tube (114), the inner tube (103) having a piston rod (112) assembled inside therein;
a floating piston (104) inserted inside the inner tube (103), the floating piston (104) divides the inner tube (103) into a first gas chamber (102) and an oil chamber (105);
a double-acting piston fitted with a rebound and compression valve pack (107) assembled with the piston rod (112);
a second gas chamber (113) filled with pressurized gas for achieving targeted spring force for solo condition;
a bump stop (116) for providing compression during an end of a compression stroke; and
a pneumatic preload adjuster (200) to vary ride height of the two-wheeler.

2. The hydropneumatic front fork (100) as claimed in claim 1, wherein a third gas chamber (118) filled with pressurized gas of different pressure is used with the second gas chamber (113) to achieve the spring rate/force for dual conditions.

3. The hydropneumatic front fork (100) as claimed in claim 1, wherein the pneumatic preload adjuster (200) includes,
an adjuster screw (124) assembled with a bolt cap (125), the adjuster screw (124) rotating in a clockwise/anti clockwise direction to adjust the ride height;
a spacer (127) joined with the adjuster screw (124) using a counter sunk screw (130) and a sealant O-ring (129), the spacer (127) moves in a forward/backward direction with rotation of the adjuster screw (124); and
a sealant (126) assembled on the bolt cap (125) to prevent the air leakage from the first gas chamber (102).

4. The hydropneumatic front fork (100) as claimed in claim 1 is operably connected to an integrated electronic control system (300), the integrated electronic control system (300) includes,
a sensor (301) assembled on the hydropneumatic front fork (100) for continuously monitoring the pressure and temperature of the second gas chamber (113) and sending feedbacks;
an electronic control unit (302) configured to receive and store user inputs as set values for the pressure and temperature of the air in the second gas chamber (113), to compare the set values with the feedback received from the sensor (301), and to calculate the difference therebetween;
a bi-directional pump (303) for receiving signal from the electronic control unit (302) to adjust the temperature and pressure of the air and supply to the second gas chamber (113); and
a conditioning unit (304) having a heater and cooler, the conditioning unit (304) regulates the temperature of an output from the bi-directional pump (303).