WO2017048135A2

WO2017048135A2 - A valve

Info

Publication number: WO2017048135A2
Application number: PCT/NZ2016/050146
Authority: WO
Inventors: Glyn Robinson
Original assignee: Sports Motorcycles Limited
Priority date: 2015-09-18
Filing date: 2016-09-14
Publication date: 2017-03-23
Also published as: WO2017048135A3

Abstract

The invention provides an adjustable hydraulic damping valve, suitable for use in a motorcycle suspension system, comprising a main housing with a central shaft housing a first spring, a piston valve which in a first position is seated on a top plate and in a second position is located away from the top plate, a rebound plug adapted to move up and down the central shaft to create a variable gap between the bottom of the rebound plug and the main housing, a check valve located between the piston valve and the rebound plug, a rebound damping transfer inlet, a plurality of ports defining a first passage through the main housing in a first direction and a second passage through the main housing in a second direction, and adjustment means to adjust the position of the rebound plug on the central shaft and thus the size of the variable gap.

Description

A VALVE

FIELD OF THE INVENTION

The present invention relates to a valve. In particular, this invention relates to an adjustable hydraulic damping valve, suitable for use in a motorcycle suspension system. BACKGROUND

Motorcycle suspension systems are designed primarily to absorb the impact of variations in the road or driving surface. This ensures the tyres of the motorcycle retain traction with the road, improving safety and rider comfort.

Most motorcycle front suspension systems comprise a spring, which compresses and extends (or rebounds) when a load is exerted or released. The rate of movement of the spring is tempered by dampers. Dampers are usually filled with oil and include at least one hole or orifice. The rate at which a damper compresses and rebounds depends on the size of the at least one hole or orifice the oil is being forced through and the viscosity of the oil.

One widely available front motorcycle suspension system that has been around since the early 1 950s utilises telescopic forks (these replaced the traditional girder design). The telescopic fork introduced a fixed, non-adjustable, internal hydraulic damping design known as the "damper rod" design. The damper rod design proved far superior to the friction arrangement commonly used in earlier girder designs.

To produce an effective and safe system, hydraulic damping is required on both compression and rebound strokes of the suspension. The damper rod system provided this, but relied on changing the oil to change the degree of damping. More viscous oil would be needed to create more hydraulic resistance and therefore stiffer damping, with a change in oil weight affecting both compression and rebound damping. By the late 1980s, motorcycles were producing ever more power. This resulted in the need for a better, more precise and tuneable suspension system. A new type of adjustable damping system, the cartridge system, was employed by some specialist race suspension suppliers and was developed on the race track by the leading factory teams of the day. Inevitably, this technology transferred to the manufacturers' Over the counter' sports bikes. This gave the rider (and privateer racer) the advantage of adjustable damping on their suspension. Essentially the same cartridge system, using similar principles, is still in use today, The development of the cartridge system created a considerable gap between the older and newer technologies and created a market for a "fix" to improve the workings of the older damper rod system. Various specialists have since manufactured retrofit cartridge kits to suit the old style damper rod forks. However, these kits can be quite complex and usually require specialist expertise to fit them correctly, making them a relatively expensive option.

In the early 1990s, a simpler and cheaper solution to the full retrofit cartridge system was developed. This system, known as the cartridge "emulator", is a dedicated cartridge system. This cartridge emulator is relatively inexpensive compared with the retrofit cartridge system and requires a low level of mechanical expertise to fit. The design permits the assembly to be fitted quite easily as an addition to existing damper rod fork components.

The cartridge emulator comprises a small valve normally fitted by the end user into existing damper rod forks. The valve has adjustment for compression damping only, and has to be removed from the fork assembly to do so (quite a messy, oily, job). The design does not address the rebound damping in any way, but relies on the fixed rate of damping within the original damper rod system. Users are instructed to adjust the return damping by changing the oil weight. However, a change in oil weight affects both the rebound and the compression damping. Thus, the user has to remove the valves again from both fork legs to make another adjustment, to counterbalance the change in oil weight.

A need therefore exists to address some of the disadvantages of currently available systems, such as the lack of adjustable rebound damping and the need to completely remove the item from the fork assembly for any adjustments to take place.

It is therefore an object of the present invention to provide an adjustable hydraulic damping valve suitable for use in a motorcycle suspension system which addresses some of the disadvantages of currently available systems, or which at least provides a useful alternative.

SUMMARY OF THE INVENTION

In a first aspect, the present invention provides an adjustable hydraulic damping valve

In one aspect, the present invention provides an adjustable hydraulic damping valve comprising:

a main housing with a central shaft housing a first spring,

a piston valve which in a first position is seated on a top plate and in a second position is located away from the top plate,

a rebound plug adapted to move up and down the central shaft to create a variable gap between the bottom of the rebound plug and the main housing,

at least one check valve located between the piston valve and the movable rebound plug,

at least one rebound damping transfer inlet,

a plurality of ports defining a first passage through the main housing in a first direction and a second passage through the main housing in a second direction, and adjustment means adapted to allow adjust the position of the rebound plug on the central shaft and thus the size of the variable gap.

In various aspects: The piston valve comprises at least one bleed valve.

In one aspect, at least one of the plurality of ports is provided in the top plate.

The first spring is adjustable to adjust the opening pressure of the piston valve. The at least one check valve is adapted to move between a first closed position and a second open position.

A second spring is provided which is adapted to facilitate movement of the at least one check valve.

A chamber is provided below the movable rebound plug and variable gap. The movable rebound plug is axially grooved.

A third spring and ball detent are provided adjacent the movable rebound plug.

A mechanical seal is located about the main housing. In a second aspect, the present invention provides a fork assembly comprising an adjustable hydraulic damping valve as described above.

In one aspect, the at least one rebound damping transfer inlet is in fluid communication with a chamber of the fork assembly.

This brief summary of the invention broadly describes the features and advantages of certain embodiments of the invention. Further features and advantages will be described in the detailed description of the invention that follows. Novel features that are believed to be characteristic of the invention will be better understood from this detailed description when considered in connection with the accompanying drawings. However, the accompanying drawings are intended to help illustrate the invention or assist with understanding the invention, and are not intended to define the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of example only and with reference to the following drawings. Figure 1 : shows a cross-sectional side view of a fork assembly according to one aspect of the present invention, during a compression stroke. Figure 2: shows a cross-sectional side view of a valve assembly according to one aspect of the present invention, during a compression stroke.

Figure 3: shows a cross-sectional side view of a fork assembly according to one aspect of the present invention, during a rebound stroke.

Figure 4: shows a cross-sectional side view of a valve assembly according to one aspect of the present invention, during a rebound stroke.

Figure 5: shows a cross-sectional side view of an adjustment tool according to one aspect of the present invention.

Figure 6: shows a plan view of one end of the adjustment tool shown in Figure 5.

Figure 7: shows a cross-sectional side view of the valve assembly and the adjustment tool according to one aspect of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

An important aspect of motorcycle front suspension systems is the control of movement in the spring of the suspension system. This is achieved, at least in part, by compression and rebound damping. Compression and rebound damping systems need to be adjustable, to accommodate rider preference, road and use conditions (for example, racing/touring) and the like. The present invention provides an adjustable hydraulic damping valve for use in a motorcycle front suspension system that allows for adjustable rebound damping, as well as adjustable compression damping. Figures 1 and 3 of the accompanying drawings show a fork assembly 1 that forms part of a motorcycle front suspension. The fork assembly 1 is securable to the front axle of a motorcycle. The fork assembly 1 comprises a housing 2, which houses a substantially hollow damping rod 3. A piston 4 is formed at the top of the damping rod 3. Slidably located within the housing 2 is a fork tube 5, which houses a main spring 6, a buffer spring 7 and an adjustable hydraulic damping valve 8. The main spring 6 supports the sprung mass of the rider and the front of the motorcycle.

The fork assembly 1 also comprises a number of chambers. These include a lower chamber 9, and medial chamber 10 and an upper chamber 1 1 .

The damping rod 3 has a plurality of orifices 12 located in a lower end thereof, so that the lower chamber 9 is in fluid communication with a further chamber 13, formed by the hollow inner portion of the damping rod 3. The chambers 9, 10 and 13 are filled with oil and upper chamber 1 1 is partially filled with oil.

The adjustable hydraulic damping valve 8 of the present invention is adapted to be secured on to piston 4, and is shown in more detail in Figures 2 and 4.

Valve 8 comprises a main housing 14, with a central shaft 15 housing coil spring 16. Valve 8 further comprises piston valve 18, top plate 19, movable rebound valve or plug 20, and rebound damping transfer inlet 21 . Further features of the adjustable hydraulic damping valve 8 are described below.

During a compression stroke, the fork assembly 1 compresses by movement of the fork tube 5 in a downward direction within housing 2 (as indicated by arrow A in Figure 1 ). This movement reduces the volume of lower chamber 9 and causes oil in the lower chamber 9 to be pushed through the orifices 12 and into the chamber 13. The oil is forced upwards in the direction shown by arrows B in Figure 1 , until it encounters an underside of the adjustable hydraulic damping valve 8. Referring now to Figure 2, at low compressive speed, oil continues to move in the upward direction B through ports 22, past spring 23, check valve 24 on its upper seat and through ports 25, until it is vented through the piston valve 18 via bleed hole(s) 26 provided in the piston valve body 14.

The piston valve 18 is normally positioned against top plate 19 (see Figure 3) and this does not change during a compression stroke at low compressive speeds. At higher compressive speeds however, the upward passage of the oil forces the piston valve 18 upwardly away from its seat, as can be seen in Figure 1 , allowing for more rapid flow of the oil out of the chamber 13. The opening pressure for piston valve 18 is adjustable by coil spring 16.

The result of the upward passage of oil (whether at low or high compressive speed) is that oil enters the upper chamber 1 1 , which houses the main spring 6. Here the kinetic energy of the compressed main spring 6 is transferred to the oil and dissipated as heat thus absorbing the shock experienced by the motorcycle.

At high compressive speed, the more rapid flow of oil forces the piston valve 18 to lift further up, giving a more linear compressive resistance and increased shock absorption.

During the compression stroke, some oil also passes from the lower chamber 9 into the medial chamber 10. As the fork tube 5 moves down in direction A, some of the oil in chamber 9 moves up through port(s) 27, opening check valve 28. When check valve 28 is open, oil can flow upwardly through ports 29 and into chamber 10. Because the volume of the chamber 10 is increasing during the compression stroke, the oil in chamber 10 remains under relatively low pressure.

After completion of the compression stroke, the fork assembly 1 undergoes a rebound stroke. This occurs when the fork assembly 1 tries to return to its normal static extended state after compression of the main spring 6. (It should be noted that compression damping has to accommodate a much wider range of velocities, generated by road surface variations of different sizes and shapes, while rebound damping primarily controls the energy of the compressed spring and therefore accommodates a smaller range of velocities.)

During the rebound stroke, fork tube 5 moves upwardly from within housing 2, as indicated by arrow C in Figure 3. (Buffer spring 7 is provided to soften the harsh effect of "topping out" when the whole assembly is in its static state and mechanically fully extended).

As the fork tube 5 moves upwardly in direction C, oil is sucked or drawn from the upper chamber 1 1 and passes freely through the main body 14 of valve 8 via ports 30 (see Figure 4) then back down into the lower chamber 9, via chamber 13. The check valve 24 is opened by oil vacating the upper chamber 1 1 and pushing against spring 23. This allows the oil to pass the check valve 24. Note: check valve 24 effectively acts as a one-way valve, directing the oil through the ports 25 on the upward compression stroke, to allow lifting of the piston valve 18 if needed, and directing the oil through the ports 30 on the downward rebound stroke.

At this point, the piston valve 18 is again closed against the top plate 19 by pressure from the coil spring 16. During the rebound stroke, the medial chamber 10 reduces in size. The resultant pressure increase closes check valve 28, resulting in oil being forced under pressure from the medial chamber 10 upwardly towards the lower outer region of the main body 14 of the valve 8. A mechanical seal 31 on the main body 14 stems any further flow of oil beyond the seal 31 .

As a result, the oil in chamber 10 is directed to pass into rebound damping transfer inlets 21 . The oil then moves into chamber 32, through gap 33 and towards the centre of the valve body 14 where it joins the oil returning from the upper chamber 1 1 to the lower chamber 9.

At this point the oil flow is restricted by means of the movable valve or plug 20, fixed to central stem 15. The movable valve or plug 20 forms and acts in conjunction with gap 33 to create an adjustable restriction to the flow of oil. This gap may be adjusted by revolving the central stem 15 by means of a thread to increase/decrease the gap (oil flow) as further described below. Increasing the size of the gap 33 increases the rate at which oil is returned to the main valve body 14, which decreases the rebound damping. When setting up a motorcycle front suspension comprising the adjustable hydraulic damping valve of the present invention, the stiffness of the suspension may be adjusted, both for the compression stroke and for the rebound stroke. Adjustment is achieved using an adjusting nut 32, which is located about the central stem 15 at the top of the valve 8.

For the compression stroke, a stiffer suspension is obtained by increasing the damping effect, which is achieved by increasing the resistance exerted by the piston valve 18 against the flow of oil. Increasing the pre-load exerted on the piston valve 18 is achieved by adjusting the adjusting nut 32 downwardly against spring 16. Conversely, a softer suspension is achieved by decreasing the pre-load exerted on the piston valve 18 by adjusting the adjusting nut 32 upwardly away from the spring 16.

For the rebound stroke, the damping effect is increased by reducing the size of gap 33. This is achieved by turning bolt head 34 which is located on the central stem 15 above the adjusting nut 35. Turning the bolt head 34 in one direction rotates the central stem 15, which in turn winds the movable valve or plug 20 closer to its seat. Conversely, turning the bolt head 34 in the other direction rotates the central stem 15, which in turn winds the movable valve or plug 20 away from its seat. In one preferred aspect of the invention, adjustment of the adjustable hydraulic damping valve 8 may be achieved using the adjustment tool 36 shown in Figures 5 to 7.

The tool 36 may be used to adjust the valve 8 for both compression damping and rebound damping.

The adjustment tool 36 comprises a substantially elongate stem 37 with an adjuster head 38 at one end. As shown in Figure 6, the adjuster head has first adjustment means 39 for turning the adjusting nut 35 and second adjustment means 40 for turning the bolt head 34 (in one aspect the bolt head 34 may be an Allen key configuration).

To adjust the valve 8 for compression damping, the adjustment tool 36 is located inside the fork assembly 1 so that the first adjustment means 39 is located about adjustment nut 32 and the nut 32 is then turned in the desired direction.

To adjust the valve 8 for rebound damping, the adjustment tool is located inside the fork assembly 1 so that the second adjustment means 40 is located within bolt head 34 and the bolt head 34 is then turned in the desired direction.

The first and second adjustment means 39 and 40 can be turned independently of each other. If desired, however, the adjustment means 39 and 40 may be turned simultaneously.

Figure 7 shows the tool 36 in position about the upper portion of valve 8, ready to make adjustments to the valve.

In another aspect of the present invention, the movable valve or plug 20 may be axially grooved (see 41 in Figure 4). The grooves 41 act together with a spring 42 and ball detent 43 to create a positive position when adjusting the movable valve or plug 20 (and thus the size of gap 33). It should also be appreciated that the size of gap 33 may be mechanically restricted to a maximum opening adjustment by the top of nut 44 coming into contact with the underside of valve body 14 when considered fully open.

From this description, it will be appreciated that the adjustable hydraulic damping valve of the present invention allows for adjustable rebound damping, as well as adjustable compression damping. In one particularly preferred aspect, the adjustable hydraulic damping valve of the present invention allows for adjustment of rebound damping while the valve is still in situ. This has the advantage that the valve does not have to be removed from the fork assembly, making adjustment a quicker and much cleaner task. The present invention and its embodiments have been described in detail. However, the scope of the present invention is not intended to be limited to the embodiment described in the specification. Modifications and variations may be made to the disclosed embodiment without departing from the scope or essential characteristics of the present invention.

Claims

1 . An adjustable hydraulic damping valve comprising:

a main housing with a central shaft housing a first spring,

at least one check valve located between the piston valve and the rebound plug,

at least one rebound damping transfer inlet,

a plurality of ports defining a first passage through the main housing in a first direction and a second passage through the main housing in a second direction, and adjustment means adapted to allow adjust the position of the movable rebound plug on the central shaft and thus the size of the variable gap.

2. An adjustable hydraulic damping valve as claimed in claim 1 , comprising at least one bleed valve.

3. An adjustable hydraulic damping valve as claimed in claim 1 , wherein at least one of the plurality of ports is provided in the top plate.

4. An adjustable hydraulic damping valve as claimed in claim 1 , wherein the first spring is adjustable to adjust the opening pressure of the piston valve.

5. An adjustable hydraulic damping valve as claimed in claim 1 , wherein the at least one check valve is adapted to move between a first closed position and a second open position.

6. An adjustable hydraulic damping valve as claimed in claim 1 , wherein a second spring is provided which is adapted to facilitate movement of the at least one check valve.

7. An adjustable hydraulic damping valve as claimed in claim 1 , wherein a chamber is provided below the movable rebound plug and variable gap.

8. An adjustable hydraulic damping valve as claimed in claim 1 , wherein the movable rebound plug is axially grooved.

9. An adjustable hydraulic damping valve as claimed in claim 1 , comprising a third spring and ball detent, located adjacent the movable rebound plug.

10. An adjustable hydraulic damping valve as claimed in claim 1 , comprising a mechanical seal which is located about the main housing.

1 1 . A fork assembly comprising an adjustable hydraulic damping valve, the adjustable damping valve comprising:

a main housing with a central shaft housing a first spring,

at least one rebound damping transfer inlet,

12. A fork assembly as claimed in claim 1 1 , wherein the at least one rebound damping transfer inlet is in fluid communication with a chamber of the fork assembly.