Synchronized transmission, in particular for motorcycles

Synchronous drives especially for locomotives

SYNCHRONIZED TRANSMISSION, IN PARTICULAR FOR MOTORCYCLES

The present invention relates to a synchronous transmission, which can be used on a vehicle, in which the crankshaft actuated by the engine and the drive shaft connected to the rear wheels are substantially parallel between the two and parallel to the synchronous The main shafts are movably connected to the crankshafts in a manner such as by means of pulleys assembled on the respective shafts and at least one belt therebetween.

This means that what is discussed below can be applied to even other types of synchronous transmissions, eg transmissions using pinion-chain-toothed wheels.

In particular, the invention concerns a specific case in which the main shaft has at least one gear wheel assembled on a free wheel arranged on the main shaft, which transmits the motion to the drive shaft.

Typically, this architecture is used in so-called Continuously Variable Transmission gearboxes or continuously automatic In gearboxes, in which the action transmission is not of the synchronous type, but when the gear ratio change is carried out by changing the circumference of the belt on two pulleys with opposing tapered surfaces, a clutch is involved, both of the synchronous type The gearbox, which guarantees several predetermined mechanical speed ratios, and the synchronizing mechanism allows the speed change to be carried out by acting on the clutch device provided to initiate the actual transmission between the two input and output pulleys on the drive shaft .

In order to effect the shifting from one speed to another, an assembly of one or more pulleys on the drive shaft on the free wheel can be provided so that they can rotate if they are not involved in the motion transmission.

However, this can remove, especially in high gear, the engine braking effect by making more difficult vehicle control during ramp down or at high speeds.

US 4,505,352 A discloses a synchronous transmission using a main shaft interposed between a crankshaft and a drive shaft, the main shaft having gears transmitting motion to a drive shaft assembled on a free wheel, i.e. a one-way clutch, in which the free The reversibility of the wheel cannot be ruled out.

The technical problem underlying the present invention is to provide a synchronous transmission that allows avoiding the disadvantages mentioned with reference to the prior art.

This problem is solved by means of a synchronous transmission as specified in claim 1 attached hereto.

The main advantage of the synchronous transmission according to the invention is that it allows better vehicle control thanks to the braking effect of the engine even at high speeds.

<p>1: support plate</p><p>2: Actuating end</p><p>3: Bell spring</p><p>5: Bearing</p><p>6: Cam</p><p>9: Cam Follower</p><p>10: Actuating the mandrel</p><p>16: Control Wheel</p><p>20: Second Synchronizer</p><p>21: clutch pulley</p><p>22: Clutch Belt</p><p>23: Gear selector</p><p>24: Electric Motor</p><p>40: Disc pressure element</p><p>41: Clutch Disc</p><p>42: Clutch Disc</p><p>43: Edge</p><p>44: Leaf spring</p><p>45: Through the channel</p><p>52: Tubular element</p><p>53: Spindle</p><p>60: First free round</p><p>61: First gear</p><p>62: Second free round</p><p>63: Second gear</p><p>64: Third gear</p><p>65: Drive Wheel</p><p>70: handle</p><p>71: Slit</p><p>72: Push end</p><p>73: Thrust plate</p><p>74: Clutch Bushing</p><p>75: External axial teeth</p><p>76: Drive Bushing</p><p>77: Second outer axial tooth</p><p>78: The first inner axial tooth</p><p>100: locomotive (scooter)</p><p>101: Seat</p><p>102: Chassis</p><p>103: Front Wheel</p><p>104: Handlebars</p><p>105: Rear drive wheel</p><p>106: Propulsion unit (engine)</p><p>107: Engine body</p><p>108: Cylinder</p><p>109: Container</p><p>110: Cover</p><p>111: Bolts</p><p>114: Front connector</p><p>115: Rear connector</p><p>116: Rear suspension</p><p>200: Transmission</p><p>202: Crankshaft</p><p>205: hub axle</p><p>206: Gearing</p><p>207: Gearing</p><p>208: Clutch</p><p>209: First pulley</p><p>210: Second pulley</p><p>211: First Belt</p><p>212: The third pulley</p><p>213: Second belt</p><p>214: Fourth pulley</p><p>216: First Synchronizer</p><p>230: Piston Rod</p><p>A: axis</p>

The invention will hereinafter be described according to preferred embodiments with reference to the accompanying drawings, which embodiments are provided by way of illustration and not for restrictive purposes, in which: Figure 1 shows a scooter incorporating a transmission according to the invention 2 shows a perspective view of the transmission of FIG. 1 and the associated engine block closed in its container; FIG. 3 shows an axonometry view of a synchronous transmission according to the invention , a synchronizer according to the invention incorporated at the rear wheel of a locomotive; FIG. 4 shows a diametrical section of an example of an axially actuated synchronizer; FIG. 5 shows another diametrical section of the axially actuated synchronizer of FIG. 1 , with partially enlarged components; and FIG. 6 showing the actuation of the axially actuated synchronizer of FIG. 4, and the associated motion transmission.

Referring to FIGS. 1 and 2 , the entirety of the locomotive (and in particular the Scooter) is designated 100 . The present invention relates to the field of ride-on vehicles or vehicles driven across the ground, generally having two, three or four wheels, with particular reference to a scooter having a position within the chassis 102 arranged below the saddle 101 The propulsion unit, the chassis 102 is here shown laterally, and is driven from the handlebar 104 The moving front wheels 103 extend to the rear drive wheels 105 .

The propulsion unit 106 ( FIG. 2 ) or simply the engine is a type of engine having one or more cylinders arranged in a tilted position approximately on the mid-plane of the vehicle, during straight forward motion Corresponds to the rotation plane of the two wheels.

Engine 106 has a one-piece engine block 107, which in this embodiment receives cylinder 108 and associated (not visible) piston.

The piston acting in cylinder 108 is connected to crankshaft 202, which is positioned laterally and perpendicular to the mid-plane. On the side represented by the scooter 100 ( FIGS. 1 and 2 ) there is provided a transmission 200 , or more briefly, the transmission of motion from the crankshaft to the hub of the rear drive wheel 105 .

The transmission 200 has a container 109 which receives the transmission elements inside it, as will be described in more detail below. The container 109 is connected to the engine block 107 by creating a tunnel-like housing that includes the crankshaft 202 and all transmission elements connected to the crankshaft.

Furthermore, the container 109 is closed on the exposed side of the locomotive 100 by the cover 110 of the transmission 200 which extends generally from the engine 106 to the hub axle of the rear drive wheel 105 . The cover 110 is fastened to the container 109 by means of suitable bolts 111 . Openings, slots, air inlets may be provided for access and/or cooling of the transmission elements through the cover body 110 .

The cover body 110 rests on the fixed edge 112 of the container 109, is provided with a fixed seat 113 for the bolt 111, and has an additional front connecting seat 114 and a rear connecting seat 115, the front connecting seat 114 has a hinged connection of the axis A to Allowing the engine block 107 and the transmission 200 to sway, the rear connection seat 115 is connected to A rear suspension 116 to connect the container 109 and the entire transmission 200 to the frame of the locomotive 100 .

This transmission 200 is of the multi-speed and synchronous type, and is prearranged to connect a crankshaft 202 receiving motion from the action of one or more pistons to the hub axle 205 by connecting this The two axes are considered to be parallel therebetween and placed at a predetermined distance. The hub axle is equipped at its distal end with a pinion for connecting the rear drive wheel 105 .

They are all perpendicular to the vehicle's mid-plane, which is defined by the planes of rotation of the front and rear wheels. This further means that the use of this type of transmission is not limited to the two-wheeled scooters represented here, but can be extended to a scooter with a pair of front wheels or a four-wheeled scooter.

By referring to FIG. 3 , the composite gearbox without the container 109 and the cover 110 (especially the transmission with four-speed shifting) is designated as 200 as a whole. It is of a type suitable for being assembled on a locomotive as a transmission element which actuates the drive wheels of the locomotive, in particular a scooter, ie the rear drive wheels 105 thereof.

In this respect, it comprises a crankshaft 202, the piston rod 230 of which is represented, as a main shaft 53 (Fig. 4), as a crankshaft 202 to be rotated by the engine, and a secondary shaft, which can be directly connected To the wheels, or as in this embodiment generally transmits rotation to a hub axle 205 which is connected to the vehicle's rear drive wheels 105 and which is the vehicle's drive shaft.

It should be noted that the arrangement of the shafts is such that the crankshaft 202 assumes a position substantially parallel to the axis of rotation of the drive wheel, ie parallel to the hub axle 205 . Therefore, this transmission element has the power to transmit the action from the engine to the wheels For the purpose, the engine has a crankshaft that traverses the locomotive, and the wheels also have an axis that traverses the vehicle.

The passage from the layshaft to the hub axle 205 is formed through a pair of gears 206, 207, which have the function of reversing the direction of rotation of the driven wheels (which in this case coincides with the direction of rotation of the crankshaft 202), And they introduce a fixed reduction ratio on the hub.

This means that the hub axle 205 can be constituted by the same layshaft, as long as the aforementioned reduction ratio on the hub is given up and provided to reverse the direction of rotation of the crankshaft 202 .

In view of the above, in each case, from a mechanical point of view, the layshaft is connected directly or indirectly to the rear drive wheel 105 to which the gearbox is referred.

The crankshaft 202 and the main shaft 53 are generally parallel, and they are connected by means of transmission elements that allow the transmission of actions according to different speed ratios. Such transmission elements include a first set of geared pulleys assembled on crankshaft 202, a second set of geared pulleys assembled on main shaft 53, and extending from the first set of pulleys to the second set One of the set of pulleys is a pair of drive belts.

In the case of a drive belt, any flexible endless element is meant to be suitable for driving action between two pulleys that are offset from each other, especially with parallel shafts therebetween. The drive belt then includes any type of belt or chain, in which case the pulleys can be meshed to effect a synchronous connection.

In this embodiment, the drive belt is advantageously a timing belt; in the case of a timing belt, the belt (usually a geared belt or a roller chain (roller chain) means the transmission of action from a wheel or gear pulley to another wheel or gear pulley with a transmission ratio determined by the ratio between the diameters of the wheels, without it will experience clutch or slip losses.

Generally, however, the transmissions described herein are of the synchronous or nearly synchronous type and use a pair of pulleys kinematically connected by a belt, preferably a geared belt on a geared pulley or High-performance belts, such as those of the Stretch Fit® type, etc.

This means that what is described below can be fully or partially applied to even other types of equivalent synchronous transmissions, eg pinion-chain-gear transmissions.

The lack of a sliding portion and/or a portion dragged by friction that is typically used in place of a CVT (continuously variable transmission) type gearbox (even referred to as a continuous transmission or continuous transmission) results in a synchronous type of shifting as described herein box.

Therefore, in the present embodiment and the following embodiments, the above-mentioned pulley is a geared pulley connected by a geared belt, preferably a type made of rubber.

A main starting clutch 208 is assembled on the crankshaft 202, which in this example is of the centrifugal type known in the art. In this example, this type of clutch allows motion transmission from the crankshaft 202 to the tandem transmission element, and it is automatically engaged with a rotational state contained within a predetermined range, for example, between 1000 and 2000 revolutions per minute between. In the lower rotational state, clutch 208 is not engaged and the engine is idle, and the drive wheels are not engaged force.

However, this means that, in specific applications, clutches of this type can be replaced by fully equivalent manually connected clutches, or by servo-mechanism actuated clutches.

On crankshaft 202, first pulley 209 and second pulley 210 are locked to clutch 208 in a cascade manner. They are connected to the third pulley 212 by the first belt 211 and to the fourth pulley 214 by the second belt 213, respectively.

In front of the crankshaft 202, there is a first synchronizer 216 for synchronizing the second belt 213, which is the connection between the second pulley 210 and the fourth pulley 214, and in front of the main shaft 53, there is a first synchronizer 216 Two synchronizers 20 , which synchronize the gears locked to this main shaft 53 .

In fact, the first and second gears are locked to the main shaft 53, which respectively mesh with the third and fourth gears, both of which are locked to the secondary shaft. In this embodiment, the third gear is assembled on the second free wheel.

When the clutch 208 is activated so that it transmits action through the crankshaft 202 , the first synchronizer 216 and the second synchronizer 20 are not activated, and the first speed is transmitted through the first pulley 209 , the third pulley 212 and the first belt 211 .

At a specific moment that can be determined by the driver or automatically set by the system, the system is required to advance from the first speed to the second speed according to fairly precise implemented logic, and even in this case the transmission uses the first speed Belt 211.

In this case, however, the second synchronizer 20 arranged on the main shaft is activated and thus interferes by synchronizing the pair of gears of the transmission assigned to the second and fourth gears.

At a specific moment that can be determined by the driver or automatically set by the system, the system is required to advance from the second speed to the third speed, in which case the transmission has to use the second belt 213, according to fairly precise implementation logic.

The first synchronizer 216 placed on the crankshaft 202 is activated by synchronizing the second pulley 210 for the third and fourth gears. In the latter case, the second belt 213, now in motion, transmits the motion to the main shaft of the gearbox. When the first belt 211 and the second belt 213 move synchronously, the main shaft 53 will have two different speeds set by the transmission, but this is avoided by the presence of the free wheel, which allows the first gear and the Disengagement of the third pulley 212 associated with the second gear.

However, at the same time on the drive shaft, the second synchronizer 20 on the main shaft 53 must be deactivated to desynchronize the gear ratios of the second and fourth gears. Thus, the action reaches the main shaft via a pair of pulleys for the third and fourth gears, and the main shaft rotates at the speed set by the third gear.

It should be noted that the synchronizers must be stopped independently from the rotational speed reached by the respective main shafts, and this makes it necessary to be of the actuated type, i.e., at the decision of the system and not only by the rotational state reached. The type that is actuated or stopped after the actuation.

As a final case, the insertion of the fourth speed is still: as for the first synchronizer 216 on the crankshaft, there is no change with respect to the third gear. In fact, the second belt 213 between the second pulley 210 and the fourth pulley 214 continues to be activated.

However, for the fourth gear, even the second synchronizer 20 has to intervene, which is actuated on the main shaft 53 , by synchronizing again the pair of gears belonging to the second and fourth gears.

With reference to FIGS. 4 to 6 , the axially actuated synchronizer according to the present invention is designated as a whole at 20 , as in the previous figures, where it is shown as the second synchronizer of the transmission 200 . However, this means that the described situation can be applied to any synchronizer acting on the drive shaft.

It comprises a support plate 1 which, together with a disc pressing element 40 shaped like a cup, delimits the space contained therein. The support plate 1 covers the wide central opening of the disc pressing element 40 and it has a central hole. Between the support plate 1 and the disc pressure element 40 there are clutch discs 41 , 42 .

The second synchronizer 20 comprises an actuating axis constituted by the main shaft 53 , which is the main drive shaft in the previously described transmission, with a proximal actuating end inserted inwardly into the central hole of the support plate 1 2, and it is hollow inside with a through channel 45 in its interior. The main shaft is contained in a tubular element 52 , the proximal end of which is oriented towards the central hole of the support plate 1 of the second synchronizer 20 . The tubular element 52 is connected to the disc pressing element 40 .

The main shaft 53 extends from the support plate 1 and it passes through the remainder of the transmission element, which will now be described.

The second synchronizer 20 comprises a bell spring 3, which is generally shaped like a cone, implemented by a metal bundle, wherein through grooves are made to allow deformation of the spring according to the axial direction.

It then has the shape of a conical disc with its circumference resting on the outer edge of the support plate 1 to cover the entire central opening of the disc pressing element 40; bell-shaped The conical end of the spring 3 has a central opening with a rounded edge on which the bearing (ball bearing) 5 is fastened, which acts as a platform for assembling the cam 6, fastened outside the bell spring 3 , whose function is to translate axially against the elastic resistance provided by the bell spring 3 to interfere with the edge 43 of the central hole of the support plate 1 and with the actuating end of the spindle 53 , and on the bell spring 3 , which pushes the support plate by determining the closing of the clutch discs 41 , 42 .

In this respect, there is a leaf spring 44 between the support plate 1 and the actuating end 2 of the spindle 53, which ensures that the support plate 1 is in its starting position when it is no longer stressed (Fig. 4). elastic reset.

The cam 6 is roughly shaped like a disc and has a cam profile defined on its peripheral arc, formed by raised ribs, and a second cam profile defined by the flat surface of its exposed face. It is decided that the two profiles are connected to the respective ends by means of inclined surfaces.

The discs of the cam 6 form a plane corresponding to the exposed face perpendicular to the axis of the second synchronizer 20, and the first cam profile protrudes perpendicularly from this plane in the axial direction.

The cam 6 has a central hole into which an actuating mandrel 10 with a plug connection is inserted, allowing the cam 6 to rotate by rotating this actuating mandrel 10 .

The corresponding cam follower 9 assembled to the actuating spindle 10 , whose axis coincides with the axis of the main shaft 53 , is associated with the aforementioned cam 6 .

The cam follower 9 comprises a ring adapted to be connected with the cam 6, a second cam profile is formed on its exposed face, which protrudes axially and which is intended to engage with the cam 6 of the first cam profile connection. In this regard, it would include raised cam surfaces, lowered cam surfaces and associated inclined connections.

At the opposite distal end, the actuating spindle 10 comprises a control wheel 16 useful for rotating the cam 6 relative to the cam follower 9 , thus determining the translation of the cam 6 and thus the actuation of the main shaft 53 The translation of moving end 2.

The control wheel 16 is then rotated at the crankshaft 202 under the control of a clutch pulley 21 which is arranged at the first synchronizer 216 . The control pulley 16 and clutch pulley have a clutch belt 22 connecting them together.

The clutch pulley 21 is controlled to rotate under the control of a gear selector 23 comprising an electric motor 24, suitably controlled by a control unit or in the case of manual control.

Thus, the half rotation of the cam 6 determines the translation of itself, the bearing 5 , the bell spring 3 and subsequently the actuating end 2 relative to the cam follower 9 in one direction or the other.

In this regard, the second synchronizer 20 comprises means for selectively rotating the rotating cam, which is presented in FIG. 3 and in this example is selected by the control wheel 16 , the clutch pulley 21 , the clutch belt 22 and the gears device 23 to implement.

The main shaft 53 receives action from the third pulley 212, which is connected to the corresponding first belt 211, pulled by the crankshaft 202; and action from the fourth pulley 214, which is similar to the previous one, however assembled On the first free wheel 60 , it is dragged by the corresponding first belt 211 .

Likewise, by the first gear 61 which is then assembled to the second free wheel 62 And a pair of gears formed by a second gear 63 that only drives action in a synchronized state is locked to the main shaft 53, as will become clearer hereinafter.

It should be noted that the first gear 61, the second gear 63 will be intended to transmit action to the third gear 64 and the drive wheel 65 in different transmission ratios.

Since the cam 6 does not exert pressure against the cam follower 9 towards the actuating end 2 , the path of action provides a direct passage from the third pulley 212 via the tubular element 52 to the first gear 61 , which rotates on the main shaft 53 .

Conversely, when the cam 6 exerts pressure, by operating the clutch formed by the clutch discs 41 , 42 , the disc pressing element 40 drags and rotates the tubular element 52 , which synchronizes the second gear 63 . Due to the effect of the higher number of revolutions, the second free wheel 62 excludes the first gear 61 and the motion is transmitted through the second gear 63 .

An additional half rotation of the actuating spindle 10 brings the gearbox back to the previous situation.

Conversely, when the third speed is engaged, action is taken from the crankshaft 202 via the second pulley 210, the outermost one (FIG. 3), via the second belt 213, the fourth pulley 214, the tubular element 52, and the first Gear 61 is instead driven to a third gear 64, which is assembled on a countershaft that transmits motion to crankshaft 202 (FIG. 6).

In this case, the first free wheel 60 is engaged, which then drives the action along the above-described transmission path.

However, where the action should have the opposite direction, then from the rear drive wheel 105, the free wheel itself will disengage and will not have the Has engine braking effect.

In this respect, in the through channel 45 of the main shaft 53, the shank 70 is inserted extending from the actuating end 2 up to the slit 71 made to penetrate the main shaft 53 in the area contained between the third pulleys 212, That is, the pulley transmits motion to the main shaft, to the area of the second free wheel 62, that is, the area where the gear transmits motion to the secondary shaft.

The handle 70 then has a push end 72 at the actuation end 2 and a thrust plate 73 protruding from the slot 71 on the opposite end.

At the slit 71 , a clutch bushing 74 is provided, which is placed outside the main shaft 53 , the clutch bushing 74 has external axial teeth 75 between the clutch bushing 74 and the tubular element 52 .

The clutch bushing 74 then tends to slip on the main shaft 53, which is pushed by the thrust plate 73 and by the shank 70, which then receives the associated actuation from the cam 6 previously described or from another cam mechanism. The clutch bush 74 and the thrust plate 73 are connected to each other.

The outer axial teeth 75 are in toothed engagement with the tubular element 52 by means of the latter's first inner axial teeth 78 formed on its inner surface facing the clutch bushing 74, which 74 slides relative to it.

Finally, a drive bush 76 is provided on the main shaft 53, still outside the shaft, on which is assembled the second free wheel 62, ie on which one of the gears transmitting the motion to the layshaft is assembled free wheel.

The drive bushing 76 is formed at its end facing the clutch bushing 74 with an annular chamber in which are formed second outer axial teeth 77 which tend to mesh with the outer axial teeth 75 of the clutch bushing 74 .

If implemented, this meshing unifies the rotation of the two parts that would otherwise act to drive and be driven relative to the freewheel, essentially precluding the reversibility of the freewheel itself.

This clutch must be executed after the third speed has been engaged and after the freewheel has started to drive the motion in the desired direction for the third gear, or more simply when the shafts are synchronised by current conditions.

This means that the clutch system described here must be synchronized when a gear is engaged, but this is ensured by the fact that the second synchronizer 20 is controlled and geared.

It works by means of axial actuation, which is controlled at one end of the main shaft so as not to change the geometry of the transmission components of such a shaft.

Conveniently, actuation occurs on the same side of the synchronizer, and speed changes are handled via the same cam mechanism (still in the axial direction).

For the synchronous transmission described above, a person skilled in the art can introduce several additional modifications and variations for the purpose of satisfying additional and possibly occurring requirements, however, all of which are included in the patent application as described by the accompanying within the scope of protection of the present invention.