Two-wheeled or three-wheeled motorcycle

Abstract

The invention relates to a two-wheeled or three-wheeled motorcycle having at least one front wheel and one rear wheel connected to a frame due to a suspension system, the rear suspension comprising a swing arm connected to the frame. The swing arm may rotate about an axis (Y) to be fixed to the frame, but the swing arm may also translate along such an axis (Y) perpendicular to a median plane (W) of the vehicle.

Description

Technical Field

[0001] Forming the object of the present invention is a two- or three-wheeled vehicle, such as a bicycle or a motorcycle, according to the main aspects of the invention. Background Art

[0002] As is known, a vehicle of the above type, such as a conventional motorcycle, comprises a frame connected to at least one front wheel and one rear wheel; in the case of a motorcycle to which reference will be made by way of example in the description hereinafter, said frame supports at least one motor which contributes to the frame functions and which also serves as a drive. Such an engine may be an internal combustion engine, or an electric engine or a hybrid engine. In this document, the parts or engines cooperating with the performance of such functions will also be considered as the frame.

[0003] The engine drives a chain cooperating with a pinion or gear which is integrally engaged with the hub of the rear wheel in order to obtain the movement of the vehicle.

[0004] The rear wheel cooperates with a swing arm (which may have a single arm or two arms, usually referred to as a double arm) connected to the frame at its first end. The second end of the swing arm (if it has one arm) or the second ends of the swing arm are integrally engaged with the hub of the rear wheel using a common pin for the wheel.

[0005] The first end of the swing arm comprises two arms provided at their free ends with through holes in the manner of "small hubs" which usually accommodate pins or shafts arranged in holes provided in the frame, said holes having a longitudinal axis arranged transversely and perpendicularly to the median longitudinal plane of the motorcycle.

[0006] Plates and / or brackets may be provided which also cooperate to perform a "frame" function.

[0007] As for the method for constraining the swing arm to the frame, the shaft or pin of the arm connecting the first end of the swing arm is usually inserted into a mechanical decoupling member defined by a combination of ball bearings, rollers and / or needle cages. This constraint fixes the arm to the frame while allowing the arm to rotate around the longitudinal axis of the shaft or pin.

[0008] Although superior to the usual suspension members, the known solutions do not allow the swing arm to be moved more or less rigidly along the axis constraining it to the axis of the frame. Therefore, the stiffness along this axis cannot be calibrated (i.e. adjusted) without replacing the swing arm or parts of it. This stiffness can be particularly critical when the motorcycle is turning, in particular if it is of the racing type: in fact, the swing arm-suspension member assembly performs well the purpose provided for this purpose as long as the stresses transmitted to it are in the longitudinal plane. When this stress has a component perpendicular to this longitudinal plane, such as, but not limited to, when the vehicle is turning, this assembly may operate in a way that is not entirely correct.

[0009] It is therefore necessary to provide a solution for constraining the swing arm to the vehicle frame such that the rigidity of the swing arm guarantees an optimal absorption of the stresses in any riding step. Summary of the invention

[0010] It is therefore an object of the present invention to provide a two- or three-wheeled vehicle, such as a bicycle or motorcycle, provided with a swing arm connected to the frame such that the lateral stiffness of the entire rear axle of the vehicle (including the swing arm and the wheels) can be properly calibrated to maximize the overall performance of the motorcycle, whether it is a racing motorcycle (thus maximizing e.g. the speed at which the vehicle can turn) or a road motorcycle (thus maximizing e.g. ride comfort).

[0011] The object of the invention is therefore to allow the swinging arm to translate more or less rigidly along the aforementioned axis or pin and therefore to allow the possibility of adjusting the stiffness of the rear axle according to needs or, for example, according to the riding steps that occur during a specific path, by acting in the points that constrain the swinging arm to the frame.

[0012] Another object is to provide a vehicle of the above mentioned type in which the above mentioned adjustment is obtained in a simple and quick manner.

[0013] These objects and others which will be apparent to those skilled in the art are obtained by the vehicle according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] For a better understanding of the invention, the following drawings are attached by way of non-limiting examples only, in which:

[0015] Figure 1 shows a cross section of a portion of a vehicle according to the invention, in which a rear swing arm is fixed, the vehicle being, for example, a motorcycle;

[0016] Figure 2 Shows Figure 1Detailed view of

[0017] Figure 3 A perspective view of a motorcycle according to the invention is shown. DETAILED DESCRIPTION

[0018] With reference to the aforementioned figures, a motorcycle 100 comprises a common frame 110, a front wheel 120, a rear wheel 130, an engine 140 associated with the frame and a rear swing arm functionally constraining the rear wheel to the frame. The expression "functionally" is used to indicate that the swing arm is fixed to a part or component of the motorcycle that is fixed to the frame. In particular, the swing arm can have one or two arms constrained to the hub of the rear wheel; the swing arm comprises at a first end two arms 1 and 2 shaped so as to accommodate between them the part of the vehicle to which the two arms are fixed.

[0019] The swing arm 150 may be connected to the crankcase 4 of the engine, in which case the crankcase 4 cooperates with the frame and the crankcase may be considered to be part of the frame. Figure 1 , wherein the end portions or "small hubs" 3 of the arms 1 and 2 are connected to the crankcase 4 by corresponding threaded pins 5 inserted into corresponding threaded holes 8 of the crankcase.

[0020] As in the case shown in the figures, the pins may be supported by plates 10, 11 which are constrained to the frame and integrally joined to it (and thus become part of it) in any known manner.

[0021] The swing arm or its hub 3 can rotate during the movement of the motorcycle over the ground or road about a pin 5 (as shown, coaxial along the same axis Y orthogonal to the vehicle's mid-plane W). This rotational movement occurs against a common suspension member (not shown) constrained to the swing arm and the vehicle's frame in a known manner.

[0022] According to the invention, the possibility is provided of calibrating the lateral rigidity of the fork 150 and therefore of the entire rear axle of the motorcycle, said calibration being adapted to be obtained along the aforementioned axis Y and providing the possibility of moving the swinging arm along this axis against a special elastic element.

[0023] Before going into the details of the invention, it should be observed that the rotation of each hub 3 around the corresponding pin 5 usually takes place by providing a mechanical decoupling member or ball bearings and / or roller bearings, axial bearings and / or radial bearings and / or tilting bearings interposed between the swing arm, the frame and the pin. According to the invention, the above-mentioned bearings are replaced by mechanical decoupling members 12 and 13 suitable for allowing each hub 3 to rotate and translate around the axis Y and therefore the entire swing arm to translate along this axis. However, the suspension has an equalizing device and is therefore not affected by small lateral displacements. The swing arm is constantly free to move laterally along the axis Y, in addition to in the longitudinal plane W.

[0024] Each mechanical decoupling member 12 , 13 may take various shapes as long as they obviously ensure an appropriate friction coefficient: for example, they may be low-friction sliding bushings with hydrostatic bearings, with balls, linear bushings, etc.

[0025] An embodiment of such a decoupling member is shown in the figures. According to the embodiment shown in the figures, in the hole 14 of each hub 3 there is arranged a cage 16 containing a plurality of balls 18 in two sections 16A, 16B of the cage. In each section 16A, 16B, the balls 18 are held on respective opposite sides by retractable rings 19 and 20 (O-rings) on which they strike during each movement in a direction parallel to the axis Y caused by lateral forces introduced, for example, by a depression encountered by the vehicle when turning.

[0026] At least one of the mechanical decoupling members (in Figure 1 In the embodiment, a mechanical decoupling member 11 on the left cooperates with an elastic or viscoelastic element, such as a Belleville washer 21, which is arranged at the opposite end of the retaining frame 16 (and therefore at the opposite end of the member 12); this Belleville washer 21 allows the lateral stiffness of the swing arm to be calibrated or adjusted in a centralized manner.

[0027] According to the invention, the swing arm can therefore rotate about the axis Y, but it is also free to slide along the axis Y; this movement being counteracted by the Belleville washer 21 of calibrated stiffness.

[0028] The displacement along the axis Y is allowed by the lateral sliding of the balls in the respective cages and by the presence of the collapsible rings 19 and 20 , taking advantage of the low friction existing between the balls 18 and the corresponding pins 5 .

[0029] The lateral displacement of the swing arm may be small (a few millimeters), but still sufficient to allow excellent absorption of stresses.

[0030] A preferred embodiment of the invention has been described above with reference to a motorcycle. However, the invention can be applied to a bicycle. However, according to the above description, other embodiments can be provided: for example, Belleville washers can be provided at the mechanical decoupling members 12 and 13 arranged at the two hubs 3, or they can be non-metallic elements, and the decoupling elements can be defined by other prior art low-friction motion and decoupling means instead of balls. Another solution is that the single pin 5 is replaced by an axle connecting the plates 10 and 11.

[0031] Even these solutions fall within the scope of protection of the invention as defined by the attached claims.

Claims

1. A two-wheeled or three-wheeled motorcycle, comprising: a frame (110), the frame (110) being supported by at least one front wheel (120) and by at least one rear wheel (130), the frame (110) supporting at least one drive member, such as an internal combustion engine (100) and / or an electric engine and / or a hybrid engine; a swing arm (150), the swing arm (150) functionally connecting the frame with the at least one rear wheel, the swing arm (150) comprising two arms (1, 2) at a first end, the two arms (1, 2) being connected by a At least one pin (5) connected to the end portion (3) of the arm (1, 2) is functionally connected to the frame, the end portion (3) being connected to the pin (5) by means of a mechanical decoupling member (12, 13) inserted into a corresponding hole (14) of the end portion (3) in which the pin (5) is located, the pin having a longitudinal axis (Y) about which the end portion (3) rotates during movement of the motorcycle, the longitudinal axis being perpendicular to the mid-plane (W) of the vehicle, characterised in that The end portions (3) of the arms (1, 2) of the swing arm also move along the longitudinal axis (Y) of the pin.

2. The motorcycle according to claim 1, characterized in that: Each of the mechanical decoupling members (12, 13) is a low-friction sliding type decoupling member.

3. The motorcycle according to claim 2, characterized in that: The decoupling member is alternatively a low-friction sliding bushing with hydrostatic bearing, a linear bushing or the like.

4. The motorcycle according to claim 2, characterized in that: The mechanical decoupling member comprises a cage (16) having at least a plurality of balls (18) interposed between retractable annular elements (19, 20) arranged at both ends of a series of the balls (18) in the cage (16).

5. The motorcycle according to claim 4, characterized in that: The cage (16) comprises two sections (16A, 16B) each containing a plurality of balls (18) interposed between collapsible annular elements inside each cage section.

6. The motorcycle according to claim 2, characterized in that: At least one of the decoupling members (12, 13) cooperates with elastic elements (21) arranged at opposite ends of such decoupling member (12).

7. The motorcycle according to claim 6, characterized in that: The elastic element (21) has a predetermined but variable stiffness.

8. The motorcycle according to claim 6, characterized in that: The elastic element is a Belleville washer.

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