The present invention refers to a wheel with a suspension system. Such wheels can particularly be used in self-propelled vehicles, like wheel chairs and bicycles. Furthermore, these wheels can also be used for suspension of any rotatable mass including wheels of motorized or otherwise powered vehicles.
Furthermore, the present invention refers to a centralizing unit comprising a suspension system, whereby this centralizing unit may, according to the invention, be part of a wheel.
Rotating masses tend to accommodate vibrations and shocks due to internal and/or external forces and impacts from surfaces in contact. One example is the vibratory motion of a wheel when it travels a distance on a non-purely smooth surface. Motorized and other vehicles commonly include cumbersome suspension systems in order to protect their chassis or other affiliated parts from early failure as well as to avoid unpleasant conditions to passengers.
Suspension systems, mostly including springs and spring elements, are commonly connected to static parts of the machine or vehicle, on one end, and in direct contact with the axle or other elements that provide a stable axis of rotation to the rotating mass or rotator. For example, a wheel that travels over a rough surface will transfer axial, vertical and other forces (e.g., impacts and/or vibratory) to the axle, which will be partially absorbed and diminished using suspension means that can be located between the axel and the chassis. Several attempts are known for implementing suspension mechanisms inside the wheels.
In recent years there is a growing trend towards more efficient self-propelled vehicles where the invested human power is transferred to movement of the vehicle with minimal energy loss. Modern wheelchairs and bicycles incorporate lightweight structural parts, wheels structures with improved strength-weight ratio, tires designed for minimized resistance to rolling, etc. There is also a preference of most riders to feel a rigid or responsive ride, rather than a soft one, especially when driving over substantially smooth surfaces and/or when riding upward inclines, and also when accelerating, decelerating or maneuvering. When suspension is implemented the manufacturers usually make some accepted tradeoffs between the physiological and improved comfort needs with the dynamic preferences of the users.
From GB 2 188 596, it is known to provide a wheel of a wheel chair with resilient spokes. These spokes are located non-radial so that the spokes can be flexed due to an impact. This wheel has the possible drawback that due to the high stress of the spokes, the spokes may break.
Another wheel having an implemented suspension mechanism inside the wheel is known from DE 10 2005 032 537. This car wheel has radial located spokes that are comprising an hydraulic damper. The possible drawback of the use of such dampers is that the damping characteristics by compressing the damper differ from the damping characteristics by elongating the damper. Since the wheel has a number of regularly located dampers, a damper being located opposite to the damper being compressed, has to be elongated. Due to the different damping characteristics, the rotation of the wheel becomes uneven. Furthermore, the dampers described in DE 10 2005 032 537 cannot be preloaded.
Therefore, it is one object of the invention to provide a wheel, particularly a wheel for self-propelled vehicle such as a wheel chair or a bicycle, having a smooth and even damping system.
This and other objects are solved by a wheel according to claim 1. And by a centralizing unit according to claim 26.
The present disclosure can be related or implemented in any rotatable mass including wheels having a hub in concentric relation with a rim, when in nominal state.
A wheel according to the invention is connected or connectable to a vehicle, particularly to a self-propelled vehicle, a wheel chair or the like, or to other vehicles like cars, motorbikes etc. The wheel has a hub comprising an axle or being connectable to an axle. This hub may comprise a bearing, whereby particularly an inner ring of the bearing can be connected to the axle. Furthermore, the wheel comprises a rim being rotatable around the axle. The rim may particularly comprise a wheel rim, a tire, a hub, a bearing outer ring etc. Between the hub and the rim, at least one, particularly a plurality of support members, are located. The support members are normally providing a fixed distance between the station member and the rim. According to the invention, the support member is adapted to retain this distance when stressed up to a threshold value and to recoverably alter this distance when stressed over this threshold value. According to embodiments of the invention, this function of the support member is derived by a spring member, being part of the support member or building the support member. The spring member stores mechanical energy at compression, and in a preferred exemplary embodiment, the spring member is preloaded to a predetermined threshold value, thereby compresses only to compressive forces greater than the threshold value. In some embodiments, the spring member includes or is coupled or otherwise functionally linked to a damper, that is effectively operable (e. g., absorbs or dissipates kinetic energy) only during spring member change of size, or optionally only during its compression. In some embodiments, the spring member is in both ways compressed by the stroke, if the support member compresses and if it elongates. By compressing the spring member independent of compressing or elongating the support member, an identical dampening characteristic is optionally given. Therefore, the present invention has the advantage that particularly a wheel having a number of support members being located between the hub and the rim, can be smoothly damped, preferably only at strokes or shocks in a magnitude above a predetermined threshold value. Within a preferred embodiment of the invention, the supporting member comprises two longitudinal elements being slidably connected to each other. The two longitudinal elements are optionally comprising two cylinders, or a cylinder and a rod, one located inside the other. The spring element and/or damper can be located in and/or between the two longitudinal elements so that a relative movement of the longitudinal elements to each other causes the spring element and/or damper to be compressed.
In some embodiments, both end portions of the spring element and/or damper are connected to one of the two longitudinal elements, whereby optionally, both end portions of the spring element are connected to the inner longitudinal element. In this preferred embodiment, the spring element surrounds the outer longitudinal element. In another preferred embodiment the connection is the other way around so that both end portions of the spring element are connected to the outer longitudinal element, whereby the spring element is preferably located inside the inner longitudinal element.
In some such optional embodiments, fixing elements are connected to the end portions of the spring element and the inner or the outer longitudinal element. These tracked sliding elements are preferably passing through longitudinal slits, which are preferably located in both longitudinal elements. The outer ends of these longitudinal slits being directed in the damping or moving direction of the damper are the stoppers of the damper. If the damper is preferably preloaded, both tracked sliding elements are pressed against the outer ends of the longitudinal slits due to the force of the damper caused by preloading. The tracked sliding elements are connecting the spring element to the inner or the outer longitudinal element and having preferably a pin-like shape.
The spring element may include a spring, optionally a coil compression spring or a piston spring, pneumatic or hydraulic. In case of a piston type spring, the spring element may include damping function as well, for example if a piston member thereof is provided with at least one minute opening allowing travel of flowable medium passing therethrough during strokes, in a way that transforms kinetic energy to heat by fluid friction. A damper may be provided as a separate member, optionally hydraulic cylinder type (e.g., “dashpot”), liner or rotary, or a mechanical damper operating on dry friction between solid components, an hysteresis type damper (e.g., metal or polymeric compression structures).
Furthermore, the plurality of supporting members is optionally connected to the hub in a non-radial manner. Therefore, a compression force caused by an impact to a lower located supporting member of a wheel will not be transferred directly to the axle of the wheel, but at least partly guided surround the axle of the wheel causing an elongation of a support member being located in an upper position. Such a non-radial configuration has several advantages, including increased stroke length of the support member and inner spring element and/or damper and increase in overall stability and/or strength of the entire construction. Furthermore, when the hub shifts away from concentricity with respect to the rim and the suspension is activated, the non-radial configuration of the interconnecting supporting members causes the hub also to rotate about its axis with respect to the rim, so that particularly a piston type spring element and/or damper will avoid potential “sticking” phenomena, for example if the altering force is orthogonal thereto at the stroke initiation.
Therefore, in embodiments, the hub comprises particularly radially arranged arms, whereby the supporting members are connected to the outer end portions of these arms.
Optionally, the supporting members are pivotably connected to the hub and/or the rotatable member of the wheel.
In one embodiment, the supporting members are arranged symmetrically around the hub so that the distance of neighbored supporting members are equal.
In another embodiment, two supporting members are building a pair of supporting members, whereby it is preferred that a plurality of pairs of supporting members is arranged, whereby the pairs are symmetrically located around the hub. In this embodiment, it is preferred that the end portion of the arms of the hub has two protrusions, whereby a supporting member is connected to each one of the protrusions. Two supporting members being connected with end portions of different arms form a pair of supporting members. The two supporting members of this pair of supporting members are located symmetrically to a radial line between the axle of the hub and the rim.
In some embodiments of the invention, the vehicle is a self-propelled vehicle, for example a wheelchair or a bicycle. In some embodiments, the wheel is a rear wheel in a wheelchair. In some other embodiments, the wheel includes a caster which is fixedly rotatable about at least two axes projecting from the vehicle. In some embodiments of the invention, the hub includes at least one of: an axle, a caster housing, and a bearing inner ring. In some embodiments, the rim includes at least one of: a tire, a wheel rim, a hub shell, a fork, and a bearing outer ring.
In some embodiments of the invention, the threshold value relates to a minimal shock magnitude absorbed by the wheel. Alternatively or additionally, the threshold value relates to a minimal vibration amplitude absorbed by the wheel. Alternatively or additionally, the threshold value reciprocally relates to a maximal vibration amplitude absorbed by the wheel. Alternatively or additionally, the threshold value reciprocally relates to a maximal vibration frequency absorbed by the wheel.
Furthermore, in an aspect of some other embodiments, the invention refers to a centralizing unit optionally comprising a suspension system. The suspension system comprises at least one support member. This support member has an outer longitudinal element and inner longitudinal element as described above in view of a preferred embodiment of the wheel. Particularly, the outer longitudinal element includes a lumen and comprises two slots, atop outer slot and a bottom outer slot. Additionally, the inner longitudinal element being slidable in the lumen of the out longitudinal element, comprises also two slots, a top inner slot and a bottom inner slot. A sliding pin is located in each of the two top slots and the two bottom slots. Between the two sliding pins, a spring element is located being connected to both pins. The slots are sized and arranged so that the central relative position between the two longitudinal elements the top pin and the bottom pin are pushed by a spring to a maximal distance. At any non-central relative position between the longitudinal elements, the pins are forced to approach each other to a distance smaller than the maximal distance, thereby compressing the spring located between the two pins.
The spring element is preferably preloaded so that the nominal length is smaller than a non-stressed length of the spring.
In a preferred embodiment of the centralizing unit disclosure, the centralizing unit comprises a central member connected at a first portion thereof to a first support member and at an evenly displaced second portion thereof to a second support member. Preferably, a third support member is connected to the central member, whereby the number of support members is evenly displaced. The support members are preferably identical. Loading a central member having two support members will cause one support member to elongate and the other support member to compress, whereby both spring elements of the two support members are compressed so that a cumulative compression force thereof resists the loading. The same principle that the spring elements are compressed even if the support member is elongated, occurs if a larger number of support members is particularly symmetrically located around a central member.
Hereinafter, preferred embodiments of the invention are described, referring to the drawings.
The following preferred embodiments may be described in the context of exemplary suspension mechanisms for wheelchairs, or other types of self-propelled vehicles, for ease of description and understanding. However, the invention is not limited to the specifically described devices, and may be adapted to various applications without departing from the overall scope of the invention. For example, devices including concepts described herein may be used for suspension of any rotatable mass including wheels of motorized or otherwise powered vehicles.
Common suspension systems are built to absorb interruptions and obstacles which cause deceleration and/or undesired vibration to the vehicle and/or aid the wheel in following the terrain and avoiding loss of contact with it, or grip. In doing so, the suspension systems are built to absorb and/or dissipate energy, including such that can be translated to effective kinetic energy. Furthermore, the common suspension systems (which include, for example, parts like metal springs, cushioning materials and elastomers) cause a feeling of plushness, or softness, which may cause a sense of instability, which are undesirable by many users.
In order to answer these and other considerations, the present invention provides or includes means for selective responsiveness (or irresponsiveness) according to types and/or magnitudes of absorbed interferences or perturbations.
Referring now to the drawings,
Wheelchair 10 is shown in motion adjacent a forward-facing step 21 with its front end is tilted upwardly (commonly known as performing a “wheelie”), pivoting around rear wheel(s) 11—a common practice when riding over steps, performed either by an attendant or by the wheelchair user himself. The tilting angle α may be between 0 to 40°, and optionally higher. Such tilting maneuver changes the impact angle of the wheelchair with the ground and should be considered when designing an effective suspension mechanism. In some embodiments, the suspension system of the present invention is configured for effective suspension of falls at different impact angles, optionally in angles range of at least −10° to 10°, optionally −30° to 30°, optionally −60° to 60°. Also, in some cases the drop can be taken in reverse, meaning that the rear wheels go first, while the front casters are still on the top platform, generating a mild “nose up” angle of generally less than 20°, but optionally higher.
Reference is now made to
Within
To damp a stroke or the like, the length of the support members 40 vary damping the stroke.
Within the drawings 4A-C, the support members 40 are shown in different damping situations.
In a regular, normal situation (i.e., hub 38 in concentric with rim 34), each of the support members 40 centralized and are not compressed or elongated, and a spring 50 provided therein is substantially preloaded (e.g., it is held compressed to a length being substantially smaller than its non-stressed length).
The support members comprise two longitudinal elements 52 and 54, whereby the cylindrical element 54 surrounds the inner cylindrical element 52. Therefore, it is possible to move the two longitudinal elements 52, 54, relative to each other in a longitudinal direction 56. Within the inner longitudinal element 52, the damper 50 is located. The spring 50 comprises a piston 58, being located within a cylinder 60. The cylinder 60 is, for example, filled with compressed gas or oil. Spring 50 is preloaded since at nominal position, the pins 62 are distanced such that the spring is already compressed to the threshold value. Only above the threshold it can be further compressed. The end portions of the spring 50, i.e. of the cylinder 60 and the rod 58, are each connected to a pin-like tracked sliding element 62. The pin-like tracked sliding elements are passing through slits 64 of the inner longitudinal element 52 and slits 66 of the outer longitudinal element 54. Due to the slits 64 and 66, a movement of the two longitudinal elements 52, 54 in longitudinal direction 56 is possible. Slits length provide boundaries to such relative motion, above which pins 62 are forced to move.
As shown in
In some embodiments, when at least one support member in a self-suspended wheel or in a centralizing unit according to the present invention, there is at least a second support member being elongated, optionally at same extent, optionally to a different extent. In some such embodiments, springs and/or damper installed in both support members shall compress during the first support member compression and the second support member elongation, such that both springs and/or dampers contribute to the overall mechanical energy storage and/or damping, respectively. Reference is now made to
A centralizing unit according to the invention may comprise a central member 48 being connected to three support members 40, whereby the central member 38 does not necessarily have to be connected to a hub and the support members 40 do not necessarily have to be connected to the rim (see, for example,
The principle mechanism background of a bilateral spring mechanism is hereinafter described in view of
Virtually, an infinite spring, such as a coil spring, that adheres to the linear rule of elasticity, would demonstrate substantially the same ratio between elongation to required force as it would between compression to required force (often referred to as ‘k’, or spring constant).
Therefore, if such a spring is allowed to work both as a pulling spring and as a compression spring, its behavior as depicted in the graph of
In most suspension systems the spring is installed with some portion of compression preload, in order to prevent the spring to be free at any point, hence diminishing unwanted movement of the spring while not under compression forces (see graph of
As a preloaded spring is inherently stressed in one direction (e.g., compressed), if it is prone also to shift to the opposite direction (e.g., extend) then the preloading function will not be efficient.
Therefore, while compressing the system for a certain travel (e.g., 2 cm) would require a certain amount of force, elongating the system by the same travel would require less force.
The disclosures provided herein allow bilateral suspension or centralizing unit and obviate the need for two such mechanisms (or sub-systems) to be installed in opposite directions, in order to for a mirrored image of the graph shown in
When a symmetrical preloaded springing system is implemented, both compression and elongation produce the same forces, in their respective direction, while allowing preloading function in both directions, as shown in
Such a “mirrored” springing system enables several benefits that are impossible with one-directional springs, like a bi-directional threshold and symmetrical suspension response using a single sprung element while other applications that deals with cyclic or periodic perturbations must use two systems installed in opposite directions.
The principal of a bi-directional threshold can be described as preventing motion in any direction, as long as force above a certain magnitude, like Fmin, is not exerted on the system. In this setup, any force, in any direction, that is lower than Fmin, will not derive any movement of the spring, and only forces higher than Fmin will cause the spring to travel at k ratio, in either direction (without any special push/pull connection).
This application is a Divisional of U.S. patent appl. Ser. No. 14/354,607, filed on Apr. 28, 2014, entitled: “Wheel With Suspension System And Centralizing Unit With Suspension System”, which is a National Phase of PCT Patent Application No. PCT/IB2012/001994 having International filing date of Oct. 8, 2012, which claims the benefit of priority under §119(e) of U.S. Provisional Patent Application No. 61/552,505, filed on Oct. 28, 2011. PCT Patent Application No. PCT/IB2012/001994 is also a Continuation-In-Part (CIP) of PCT Patent Application No. PCT/IB2012/000530 having International filing date of Mar. 20, 2012, which claims the benefit of priority under §119(e) of U.S. Provisional Patent Application No. 61/552,505 filed on Oct. 28, 2011 and of U.S. Provisional Patent Application No. 61/485,086 filed on May 11, 2011. The contents of all the above applications are incorporated by reference as if fully set forth herein in their entireties.
Number | Date | Country | |
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61552505 | Oct 2011 | US | |
61485086 | May 2011 | US | |
61552505 | Oct 2011 | US |
Number | Date | Country | |
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Parent | 14354607 | Apr 2014 | US |
Child | 15374256 | US |
Number | Date | Country | |
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Parent | PCT/IB2012/000530 | Mar 2012 | US |
Child | 14354607 | US |