Compact bicycle rear suspension

Abstract

The invention relates to a four-connecting-rod type rear suspension mechanism for a high-performance mountain bike. The mechanism consists of a main frame supporting a saddle and a pivoting swing arm supporting a rear wheel. And the frame and the swing arm at the rear part are connected with each other through an upper connecting rod and a lower connecting rod. The suspension mechanism is characterized in that the suspension mechanism comprises a shock absorber, the upper end of the shock absorber is connected to one end of the upper connecting rod, and the lower end of the shock absorber is directly connected to the pivoting swing arm. The invention further provides a mountain bike combined with the suspension mechanism. A suspension of this type achieves an efficient and more compact rear suspension mechanism.

Description

Technical Field

[0001] This invention pertains to the field of bicycles, particularly the type of bicycle commonly referred to as mountain bikes, that is, bicycles designed for off-road riding on dirt roads, forest trails, paths, and / or similar terrains, especially those designed for racing on such terrains. The invention relates to a suspension for the rear wheel of such bicycles, particularly a suspension known as a "four-link" suspension. Background Technology

[0002] Specialized mountain bikes designed for competition or high performance have very strict requirements in terms of design (especially in terms of frame and suspension geometry), because any small change in design can significantly improve the bike's performance and competitiveness, thereby shortening race times in different competition events.

[0003] According to the design guidelines of different competition events, mountain bikes for different competition types usually have significant differences in appearance. This makes it difficult to achieve a sufficiently unified appearance design across all mountain and cross-country competition types without sacrificing the competitiveness of the bike, so as to strengthen the public's recognition of the characteristics of a particular brand or manufacturer's models.

[0004] In particular, the "four-link" rear suspension is the most effective type of suspension in terms of damping capacity. However, it is difficult or practically impossible to be competitive in multiple racing events, maintain a uniform appearance, leave enough free space in the frame to accommodate auxiliary components (such as water bottles, air pumps, or even motors), and also leave space in the seat tube to accommodate a seat with a traditional length seatpost. Summary of the Invention

[0005] In the following description and specific embodiments, the terms "height," "upper," "lower," and "level" are used. These terms are understood in their usual sense when the suspension frame and control arms are mounted on the wheels and the wheels are supported on the ground, and "height" is measured from the ground. The term "upper" indicates a greater height in the position of the suspension, frame, and control arms, while "lower" indicates a smaller height (i.e., when the wheels are mounted and supported on the ground). The term "level" means parallel to the ground.

[0006] A first aspect of the invention provides a "four-link" type rear suspension mechanism for a bicycle with two or more wheels. This mechanism includes a frame designed to support the saddle, the frame consisting of three links forming a first triangle. The mechanism also has a pivoting triangular swing arm consisting of two pairs of long links and two short links forming a second triangle. The pivoting swing arm is designed to support the wheels. The main frame and the pivoting swing arm are interconnected by upper and lower links, both of which are hinged. The suspension mechanism is characterized by a shock absorber, one end of which is connected to the first upper link, and the other end of which is lower than the first end and directly connected to the short links of the pivoting triangular swing arm.

[0007] The rear suspension mechanism described above allows for the creation of a suspension with high damping capacity, while also providing greater design freedom in determining the hinge points of the links and the positions of the shock absorbers within the suspension mechanism. This helps to adapt the mechanism to the kinematic and design requirements of various competition events and achieve a higher degree of aesthetic uniformity among bicycles adapted to different competition events.

[0008] The rear suspension mechanism described above can achieve a more compact structure compared to existing suspension mechanisms, and helps to form smaller and lighter control arms, thereby reducing unsprung mass and providing kinematic advantages.

[0009] A low-positioned shock absorber allows for more free space in the seat tube, enabling the insertion of rods of greater or standard length.

[0010] In addition, the lower placement of the shock absorbers lowers the bicycle's center of gravity, thus enabling greater maneuverability during travel.

[0011] The compactness of the suspension system allows for the use of smaller, lighter components such as links and shock absorbers.

[0012] The compactness of the suspension system allows for more space in the front triangle of the frame to accommodate components such as storage compartments, external batteries, and tool racks.

[0013] Because of the small size of the components that make up this system, this suspension mechanism allows for an increased weight-to-stiffness ratio.

[0014] Preferably, the suspension mechanism includes a hole for housing the axle of the rear wheel, the hole being located at the apex of the pivoting arm formed by the two longest links of the pivoting arm.

[0015] Preferably, the suspension mechanism is configured such that, at the position of maximum extension of the shock absorber, the height of the bore of the rear wheel axle is the same as or higher than the height of the bore of the chainring axle.

[0016] Preferably, the suspension mechanism is configured such that the connection point between the second end of the shock absorber and the pivoting control arm is located at the height between the lower link and the upper link.

[0017] Preferably, the suspension mechanism is configured such that, during use, the shock absorber is compressed between its two ends, with the compression occurring between the extension of the upper link and the connection point between the second end of the shock absorber and the pivoting control arm.

[0018] Preferably, the suspension mechanism is configured such that when the shock absorber extends, the imaginary line connecting the instantaneous rotation center of the pivoting control arm and the bore of the rear wheel axle forms a positive angle with respect to the horizontal direction.

[0019] Preferably, the suspension mechanism is configured such that as the pivoting control arm moves to compress the shock absorber, the angle formed by the imaginary line connecting the instantaneous center of rotation of the pivoting control arm relative to the horizontal direction decreases, and this angle can reach a negative value.

[0020] Preferably, the upper link includes a downwardly sloping extension toward the front of the frame.

[0021] Preferably, the upper link is hinged to the frame at a point whose height lies between the heights of the ends of the short rods of the pivoting triangular swing arm.

[0022] Preferably, the small cross angle between the support rod and the shock absorber can be between 20 degrees and 90 degrees. More preferably, this angle is between 60 degrees and 90 degrees. More preferably, this angle is between 80 degrees and 90 degrees.

[0023] A second aspect of the invention provides a mountain bike that includes a "four-link" type rear suspension mechanism according to a first aspect of the invention. Attached Figure Description

[0024] Figure 1 A side view of a suspension mechanism according to an embodiment of the present invention is shown.

[0025] Figure 2 An embodiment according to the present invention is shown. Figure 1 A perspective view of the suspension mechanism. Detailed Implementation

[0026] Mountain bike rear suspension design guidelines

[0027] The suspension mechanism described in this application is a short double-link rear suspension design, which uses coil spring shock absorbers (rear shock absorbers) mounted on two rotating links to hinge the swing arm supporting the rear wheels. The double short-link suspension is a special case of a "four-link" suspension system. A "four-link" suspension is so named because the suspension mechanism has four components: the frame, the control arms, the upper link, and the lower link.

[0028] To facilitate understanding of the specific implementation methods described below, the terminology used therein is described.

[0029] Most "four-link" rear suspension systems use links to transmit and amplify the linear motion of the rear shock absorber, translating it into complex circular or arc motion of the rear wheels.

[0030] The suspension mechanism of this application belongs to a type of linkage rear suspension design, characterized by having a "virtual pivot" or "instantaneous rotation center of the pivot arm", which controls the movement of the pivot arm, thereby controlling the movement of the rear wheel.

[0031] The instantaneous position of the virtual pivot is the intersection of two imaginary lines that extend through the pivot point of the link connecting the pivot arm to the frame. As the suspension travels, the angles of these pivots change, and the instantaneous center of rotation of the pivot arm shifts. Therefore, a typical characteristic of any double short-link suspension mechanism is its high adjustability (largely due to the greater rotatability of the short links), meaning that small changes in suspension geometry can lead to significant changes in suspension characteristics. This adjustability is beneficial because bicycles for different purposes require different performance characteristics, and this adjustability allows for meeting the specific riding needs of different models in various racing categories while maintaining aesthetic uniformity across different models.

[0032] Another key consideration in suspension design is the speed at which the shock absorber is actuated throughout the suspension travel. This speed is typically expressed as a dimensionless value, namely the ratio (mm / mm) of the vertical displacement speed of the piston rod to the actuation speed of the shock absorber. As shown in the following formula:

[0033] Leverage ratio =Vertical wheel speed / damping speed

[0034] On its own, the instantaneous leverage ratio is not an effective method for analyzing general suspension characteristics.

[0035] However, the instantaneous leverage ratio can be calculated at each point in the suspension travel to obtain the leverage ratio curve and the average leverage ratio. The shape of the leverage ratio curve, as well as the average leverage ratio, its ratio, and its asymmetry (as shown in the following formula), will define the overall characteristics of the suspension.

[0036] Suspension progressiveness (%) =

[0037] The final consideration in suspension design is the "anti-hundimiento" effect. Anti-hundimiento is the percentage of resistance to suspension compression caused by rider inertia during acceleration; 100% anti-hundimiento means that the motion caused by rider inertia during acceleration is completely offset by the tension in the chain. The value of the anti-hundimiento effect is defined geometrically, as shown below:

[0038] in:

[0039] Instantaneous head resistance (%) =

[0040] in, It is the instantaneous height of the point where the vertical line intersects the front wheel axis, and the vertical line intersects the extension of the imaginary line extending from the rear wheel contact point to the connection point between the shock absorber and the rear control arm; It is the instantaneous height of the rider's center of gravity.

[0041] Similar to the leverage ratio, anti-dive effect is typically represented graphically over the suspension travel range. Once the graph is generated, the anti-dive values ​​mentioned above are usually instantaneous values ​​at a selected dipping position, typically between 25% and 35% of the suspension travel, depending on the bicycle type.

[0042] The limitations of this definition and the resulting calculation methods may not be easily understood. The anti-nodding effect is the ratio of two typically opposing torques:

[0043] The torque generated by the rider's inertia during acceleration causes suspension compression, as does the chain tension (which resists the increase in distance between the chainring and rear axle that typically occurs during suspension compression).

[0044] As the suspension links begin to move, the distance between the rear wheel and the chainring typically increases. This means that there exists a link structure with a rear wheel axle-chainring axle distance of 435mm at the 0 position (initial position), which can steadily increase to 445mm as it travels.

[0045] While it is possible to design a suspension in which the distance between the rear axle and the chainring axle is shortened throughout its travel, such a design would result in undesirable riding characteristics.

[0046] A common misconception is that anti-pounce effects counteract pedaling vibration (the vertical vibration caused by the legs while pedaling). However, as mentioned above, this is not the case, because pedaling vibration is not taken into account in the anti-pounce calculation formula. However, bicycle rear suspension links are typically designed to have an anti-pounce value of 105% to 115% (at the suspension position after rider weight is added), which is slightly larger than the value needed to simply counteract 100% compression due to rider inertia. The actual value used can vary depending on the bicycle brand, design philosophy, intended application, desired riding characteristics, or rear shock specifications.

[0047] Anti-pounce calculations involve many assumptions, such as tire diameter, front and rear wheel teeth, riding gradient, and rider's center of gravity position. These are typically chosen based on the type of bicycle being ridden and remain constant. That is, the gear ratios used to analyze a bicycle optimized for climbing may differ from those used for a bicycle optimized for descent. Generally, the most important consideration is the effect of the instantaneous center of gravity on anti-pounce.

[0048] Description of the suspension mechanism in this application

[0049] The suspension mechanism described in this application is a four-link system design, which uses two pairs of short, co-rotating links to connect the front triangular frame members to the rear triangular frame members. The shock absorber is compressed by the upper link and the rear triangular frame.

[0050] Within the broader scope of four-link suspension, the suspension mechanism of the present invention has the following defining characteristics:

[0051] - A virtual pivot for the rear axle (the wheel is mounted on a pivot arm).

[0052] - The shorter link relative to the rear triangle (less than 1:3). The rear fork length is three times the length of the upper link.

[0053] - Links that rotate in the same direction. When the suspension is activated, the two links in use rotate in the same direction. At no time will one link rotate in the opposite direction to the other.

[0054] - The instantaneous center of rotation is not located within any link. The instantaneous center of rotation is located at the intersection of two imaginary lines extending from the two links.

[0055] - The upper pivot of the rear shock absorber is mounted on the opposite side of the upper link hinge pivot and the rear triangle.

[0056] - The lower end of the rear shock absorber is mounted on the short rod of the swing frame.

[0057] Relationship with existing double short-link suspension mechanisms.

[0058] It is clear that all the above factors are interconnected. For example, moving the lower link will affect the leverage ratio, wheel path trajectory, and anti-dive characteristics. Therefore, although double short link suspensions offer high adjustability, only a few geometries can produce a setup where all factors are optimized. Of these limited useful geometries, many are difficult to adopt due to practical reasons (e.g., the links cannot be placed inside the tires, or too close to other components such as the motor or seatpost) or aesthetic reasons (some link positions do not create a visually pleasing product).

[0059] Given the practical constraints of appearance design, modern bicycle frames typically need to meet the following three requirements:

[0060] - Longer seat post insertion length requirement

[0061] - Leverage ratio has a higher degree of gradualness

[0062] - Electric bicycles have greater restrictions on the placement of suspension components.

[0063] Due to the position of the linkage, the suspension system of this invention has specific requirements: the rear shock absorber must pass through the seat tube, which limits the seat pole insertion length. Furthermore, due to the space allocated to the motor, the shock absorber pivot position is typically high, which can lead to an unacceptably reduced seat pole insertion depth and excessively high anti-dive values. Attempts to address this issue by adjusting the lower linkage, which raises the instantaneous center of gravity, generally result in aesthetically undesirable outcomes after balancing all factors.

[0064] The suspension mechanism of this invention fundamentally changes the suspension design, solving the three problems mentioned above. In this invention, the lower end of the shock absorber is directly connected to the short rod of the pivoting triangular control arm.

[0065] The most noticeable effect of this suspension system is the reduction in the vertical height of the suspension components.

[0066] The rear shock absorber now intersects the seat tube at a more angled angle (in some cases close to a right angle) and is positioned closer to the crankshaft. This increases the length of the seat tube available for seatpost insertion.

[0067] Since the lower linkage no longer directly drives the action of the shock absorber, even on bicycles that require the lower linkage to be positioned higher than normal, anti-dive can be better adjusted while maintaining a practical and aesthetically pleasing design.

[0068] The effect of the suspension mechanism in this application on the possible leverage ratio is interesting and quite unique.

[0069] In conventional suspension systems, the rear shock absorber is suspended between two pivoting fixed links, one end of which is fixed to the front triangle, and these links have different geometries and lengths; in such structures, configurations that can enable the suspension to be more progressive than 15% are extremely limited.

[0070] The suspension mechanism of this invention is significantly different. While the upper pivot of the shock absorber remains connected to the pivoting upper link and fixed to the front tripod, the lower end of the shock absorber is connected to the short link of the rear tripod. This means that the pivoting arm follows a path controlled by an instantaneous center of rotation, and its distance from said instantaneous center of rotation remains constant. This provides additional degrees of freedom for the movement of the lower end of the shock absorber, facilitating a more progressive kinematic design.

[0071] Increasing the number of pivots typically increases the freedom of suspension link design, thus providing greater adjustability. However, increasing the number of pivots also brings some downsides: most notably, the increased number of components such as links, shafts, and bearings leads to higher maintenance costs and greater complexity.

[0072] Other possible drawbacks are:

[0073] - Reduced rigidity due to bearing clearance and / or connecting rod bending (as adequate reinforcement of all connecting elements may be challenging).

[0074] - Due to the increased number of bearings and / or bushings, greater friction is generated during suspension travel.

[0075] - Due to the cumulative tolerances of many parts, design characteristics are lost, and these parts require lower tolerances to function properly according to the design intent.

[0076] A four-link suspension design in which the rear axle and the lower end of the shock absorber move with the movement of a migrating virtual pivot, while the upper end of the shock absorber travels in a circular motion, giving the rear axle two degrees of freedom and the shock absorber fixed to the lower end of the swing arm three degrees of freedom. This design structure is extremely rare.

[0077] Figure 1 A side view of a suspension mechanism 10 according to an embodiment of the present invention is shown. Figure 2 It shows Figure 1 A perspective view of the suspension mechanism 10 shown.

[0078] The suspension mechanism 10 includes a frame 12, which includes a front triangular section and a rear pivot arm 14, both of which are triangular in structure. The rear pivot arm 14 consists of four long rods 14a and two short rods 14b, which can optionally be connected to each other by bridging members.

[0079] Both the front triangle and the pivot arm can be made of aluminum, steel, carbon, or a combination of materials. Aluminum is popular due to its light weight, durability, and reasonable price. Steel offers greater strength and damping, but can also be heavier. Carbon fiber is extremely lightweight and has excellent rigidity and damping, but can also be more expensive.

[0080] In this particular case, both the front frame and rear control arms are made of carbon fiber reinforced composite material. The bolts are made of steel, and the lower connecting rod is made of 6061 aluminum alloy.

[0081] The suspension mechanism of the present invention also includes links (first upper link 16 and second lower link 18).

[0082] These links can also be made of different materials, although aluminum and carbon are the most common. As with other components, aluminum is popular for its lightness and durability, while carbon offers greater rigidity and reduces weight.

[0083] Finally, the suspension mechanism of the present invention also includes a bicycle shock absorber 20, which is a key component in mountain bikes and some recreational bicycles. The main function of the bicycle shock absorber is to absorb the impact and vibration of the ground, providing the rider with greater comfort and handling.

[0084] The bicycle shock absorber 20 consists of several important parts:

[0085] - Springs: Springs are an essential component responsible for holding the system in its initial stationary position, awaiting impacts from the ground. Springs can be of different types, such as steel springs, air springs, or a combination of both. Steel springs are commonly found in low-end shock absorbers or downhill bikes, while air springs are lighter and can be adjusted according to the rider's weight and road conditions.

[0086] - Hydraulic shock absorbers: Hydraulic shock absorbers are hydraulic units that work in conjunction with springs to provide controlled, smooth motion and absorb shocks. They use hydraulic fluid and a series of valves to dissipate the energy of an impact and dampen vibrations. Shock absorbers can also be adjusted for compression and rebound to suit rider preferences and road conditions.

[0087] - Valves and Adjustment Mechanisms: Bicycle shock absorbers typically have different adjustment mechanisms and valves to allow for customization and fine-tuning. These adjustments include compression adjustment (controlling the compression rate of the shock absorber), rebound adjustment (controlling the extension rate), and locking (preventing the shock absorber from moving on inclines or slippery surfaces).

[0088] In general, bicycle shock absorbers play a crucial role in improving rider comfort and performance by absorbing shocks and vibrations from the ground. The selection and configuration of shock absorbers depend on the type of bicycle and riding style, and can be adjusted according to personal preference and ground conditions.

[0089] like Figure 1 and Figure 2 As shown, a "four-link" type rear suspension mechanism 10 for a bicycle with two or more wheels includes: a frame 12 configured to support a seat, the frame 12 being formed by three links 12a, 12b, and 12c defining a first triangle; and a triangular swing arm 14 pivoting relative to the frame, the swing arm 14 being formed by two pairs of long links 14a and two short links 14b defining a second triangle and configured to support the wheels; in use, the frame and the swing arm are interconnected by a first upper link 16 hinged and a second lower link 18 hinged, characterized in that the rear suspension mechanism includes a shock absorber 20 connected to the first upper link 16 at a first end 20a and directly connected to the short links 14b of the pivoting triangular swing arm 14 at a second end 20b lower than the first end 20a.

Claims

1. A "four-link" type rear suspension mechanism (10) for a bicycle having two or more wheels, comprising a frame (12) and a triangular swing arm (14), the frame (12) being configured to support a saddle, the frame (12) being formed by three links (12a, 12b, 12c) defining a first triangle, the triangular swing arm (14) being pivotable relative to the frame, the triangular swing arm (14) being formed by two pairs of long links (14a) and two short links (14b) defining a second triangle, and constituting a... The suspension mechanism, characterized in that it includes a shock absorber (20) connected at a first end (20a) to the first upper link (16) and at a second lower link (18) hinged together to support the wheel, and the frame (12) and the swing arm (14) are connected to each other by a first upper link (16) and a second lower link (18) hinged together. The suspension mechanism includes a shock absorber (20) connected at a first end (20a) to the first upper link (16) and at a second end (20b) lower than the first end (20a) directly connected to the short rod (14b) of the pivoting triangular swing arm.

2. The suspension mechanism (10) according to claim 1, characterized in that, The suspension mechanism includes holes (22) for housing the axle of the rear wheel, the holes (22) being located at the respective apexes of the pivoted swing arm formed by the two pairs of long rods (14a) of the pivoted swing arm.

3. The suspension mechanism (10) according to claim 2, characterized in that, The suspension mechanism is configured such that, at the position of maximum extension of the shock absorber (20), the height of the hole (22) of the rear wheel axle is the same as or higher than the height of the hole (24) of the chainring axle.

4. The suspension mechanism (10) according to any one of the preceding claims, characterized in that, The suspension mechanism is configured such that the connection point between the second end (20b) of the shock absorber (920) and the pivoting swing arm (14) is located at the height between the lower link (18) and the upper link (16).

5. The suspension mechanism (10) according to any one of the preceding claims, characterized in that, The suspension mechanism is configured such that, in use, the shock absorber (20) is compressed between its two ends (20a, 20b), the compression occurring between the extension of the upper link (16) and the connection point between the second end (20b) of the shock absorber (20) and the pivoting swing arm (14).

6. The suspension mechanism (10) according to any one of claims 2 to 5, characterized in that, The suspension mechanism is configured such that when the shock absorber (20) extends, the instantaneous rotation center of the pivoting swing arm (14) forms a positive angle with respect to the imaginary line of the hole (22) of the rear wheel axle relative to the horizontal direction.

7. The suspension mechanism (10) according to claim 6, characterized in that, As the pivoting swing arm (14) moves to compress the shock absorber (20), the angle formed by the imaginary line connecting the instantaneous rotation center of the pivoting swing arm (14) relative to the horizontal direction decreases, and the angle can reach a negative value.

8. The suspension mechanism (10) according to any one of the preceding claims, characterized in that, The upper link (16) includes a downwardly inclined extension toward the front of the frame (12).

9. The suspension mechanism (10) according to any one of the preceding claims, characterized in that, The upper link (16) is hinged to the frame (12) at a point at a height between the height of the end of the short rod (14b) of the pivoting triangular swing arm (14).

10. The suspension mechanism (10) according to any one of the preceding claims, characterized in that, The small cross angle between the rod (12a) supporting the seat and the shock absorber (20) is between 20 degrees and 90 degrees, preferably between 60 degrees and 90 degrees, and more preferably between 80 degrees and 90 degrees.

11. A mountain bike, characterized in that, It includes a "four-link" type rear suspension mechanism (10) according to any one of claims 1 to 10.

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