Patent Description:
The intermediate <CIT> discloses an electromechanical rear derailleur for a bicycle including a base member attachable to the bicycle along a mounting axis, a movable member, and a linkage including pivot axes. The derailleur is a "slant parallelogram" type derailleur, which has a mounting axis of the base member and the pivot axes of the linkage arranged at an acute angle to each other.

The <CIT> as well as the <CIT> build further technical background for electromechanical rear derailleurs in the state of the art. Document <CIT> shows the preamble of claim <NUM>.

The invention provides, in one aspect, an electromechanical rear derailleur for a bicycle, including a base member attachable to the bicycle along a mounting axis. A movable member includes a cage assembly attached thereto. A linkage includes pivot axes oriented perpendicular to the mounting axis. The linkage coupling the movable member to the base member is operative to enable movement of the movable member relative to the base member in a direction substantially parallel to the mounting axis. A power source is provided with a motor electrically connected to the power source, and a transmission is coupled to and actuated by the motor to move the movable member.

Other aspects of the invention provide a rear derailleur wherein the power source is disposed on or in the base member. The linkage includes an outer link member and an inner link member. The linkage may include link pins on which the linkage pivots, the link pins defining the pivot axes. The transmission may include a plurality of gears rotatable about a plurality of gear axes, respectively, wherein the gear axes are substantially parallel to the pivot axes. The transmission may be disposed on or in the base member. The motor may be disposed on or in the base member. The power source is disposed on the base The rear derailleur may further include a clutch between the movable member and the transmission, the clutch moving the movable member responsive to operation of the transmission. The clutch may include a drive arm coupled to the transmission and a clutch spring in contact with the drive arm. The transmission may include an output gear and the drive arm is coupled to the output gear. The clutch spring may be disposed on the inner link member. The clutch spring may be disposed about the link pin that attaches the inner link member to the movable member. The motor may have a motor shaft with a motor shaft axis that is perpendicular to the pivot axes. The linkage may include link pins on which the linkage pivots, the link pins defining the pivot axes, wherein the pivot axes are substantially parallel to the mounting axis and the transmission includes a plurality of gears rotatable about a plurality of gear axles, respectively, wherein at least some of the gear axles have gear axle axes that are substantially parallel to the pivot axes.

The disclosure also provides in an alternative embodiment, which is not claimed, an electromechanical rear derail-leur for a bicycle, including a base member attachable to the bicycle. A movable member is provided having a cage assembly attached thereto. A linkage is provided coupling the movable member to the base member and operative to enable movement of the movable member relative to the base member. The derailleur includes a power source and a motor electrically connected to the power source. A transmission is coupled to and actuated by operation of the motor to move the movable member and a position detector is provided, including a magnet rotated by the transmission, a sensor to sense rotation of the magnet, a magnet guide sized and shaped to guidingly receive a portion of the magnet and position the magnet within an effective range of the sensor.

Alternatives include wherein the rear derailleur includes a magnet holder disposed in the rear derailleur, the magnet held by the magnet holder. The magnet holder may be coupled to the transmission. The rear derailleur may further include a PC board positioned in the base member and wherein the sensor is disposed on the PC board in position to sense motion of the magnet. A magnet guide may be disposed on the PC board and the magnet extends from the magnet holder. The magnet holder may be attached to a position detector gear. The position detector gear may be in contact with and actuated by an output gear of the transmission. The rear derailleur may further include a position detector gear biasing gear disposed in the derailleur and coupled to the position detector gear to reduce backlash thereof.

These and other features and advantages of the present invention will be more fully understood from the following description of one or more embodiments of the invention, taken together with the accompanying drawings.

Embodiments of the invention will herein be described with reference to the drawings. It will be understood that the drawings and descriptions set out herein are provided for illustration only and do not limit the invention as defined by the claims appended hereto and any and all their equivalents. For example, the terms "first" and "second," "front" and "rear," or "left" and "right" are used for the sake of clarity and not as terms of limitation. Moreover, the terms refer to bicycle mechanisms conventionally mounted to a bicycle and with the bicycle oriented and used in a standard fashion unless otherwise indicated.

<FIG> and <FIG> are an overview of the derailleur assembly. The basic structure of the electromechanical rear derailleur or gear changer <NUM> includes a base member <NUM>, also referred to as a "b-knuckle," which is attachable to a bicycle frame <NUM> in a conventional manner and an outer link <NUM> and an inner link <NUM>, which is pivotally attached to the base member by link pins 28a-d, for example. A moveable member or assembly <NUM>, also known as a "p-knuckle," is pivotally connected to the outer and inner links at an end opposite the base member to permit displacement of the moveable assembly relative to the base member <NUM>.

The outer link <NUM> and inner link <NUM> taken together may be considered components of a linkage or link mechanism <NUM>, for example a parallelogram-type link mechanism. Cage assembly <NUM> is pivotally connected to moveable assembly <NUM> in a conventional manner. A bicycle chain <NUM> may be engaged with a sprocket of a conventional sprocket assembly <NUM> and positioned in the cage assembly <NUM> in a conventional manner and can be shifted from one sprocket to another of the sprocket assembly by the movement of moveable assembly <NUM> and cage assembly relative to base member <NUM> in a lateral direction when mounted.

The derailleur <NUM> is of the "Straight-P" or straight parallelogram type in contrast to a "slant parallelogram" type derailleur. Straight-P derailleurs, or in other words non-slanted parallelogram derailleurs, have a linkage <NUM> with the pivot axes "PA" of the pins <NUM> (see <FIG>) forming the joints of the linkage substantially perpendicular (i.e., within a few degrees) to the axial A' direction, e.g., the mounting axis (see <FIG>). The mounting axis may be defined by the axis of a mounting bolt "B" of the derailleur or the axis of the hanger opening of the bicycle frame dropout, for example, (not shown). The pivot axes may also be considered parallel to the planes defined by the sprockets <NUM> (<FIG>). This causes the moveable assembly <NUM> to move substantially horizontally. Also, the pivot axes PA may be vertical or non-vertical (see <FIG>).

Because derailleur <NUM> is a straight-P, it has an offset jockey wheel <NUM>, meaning that the rotational axis of the jockey wheel is not coincident with, i.e., is offset from, the axis of rotation of the cage about the p-knuckle <NUM>, to accommodate the varying diameters of the sprockets <NUM>. The derailleur may also be equipped with a damper assembly <NUM> and a cage lock <NUM> at the p-knuckle as is known in some mechanical derailleurs.

A gearbox <NUM> that is disposed in and/or forms part or all of the b-knuckle <NUM> drives the linkage <NUM> and the cage assembly <NUM> through the range of motion shown in <FIG>. The gearbox <NUM> comprises a transmission <NUM>.

Referring to <FIG> (which is section C-C of <FIG>) the gearbox <NUM> includes an output shaft <NUM>. A drive arm <NUM> is mounted on the output shaft <NUM> via a castellated geometry that engages with a corresponding castellated geometry on the drive arm. The drive arm <NUM> and the output shaft <NUM> are thereby rotatably fixed to one another.

In order to drive the linkage <NUM> in the inboard direction, i.e., toward the larger diameter ones of the sprockets <NUM>, the output shaft <NUM> and the drive arm <NUM> is rotated by the gearbox <NUM> clockwise in <FIG>, which drives the inner link <NUM> clockwise via a direct engagement between the drive arm and a projection <NUM> on the inner link. In order to drive the linkage <NUM> in the outboard direction, i.e., toward the smaller diameter sprockets <NUM>, the output shaft <NUM> and the drive arm <NUM> rotate counterclockwise in <FIG>, which drives the inner link <NUM> counterclockwise via engagement with a preloaded clutch spring <NUM>, the position and function of which will be described later. In other words, the drive arm <NUM> does not directly push on the inner link <NUM> to drive it in the outboard direction. Rather, the drive arm <NUM> pushes on the clutch spring <NUM>, and the clutch spring drives the inner link <NUM> in the outboard direction. The drive arm <NUM> and clutch spring <NUM> are considered a clutch <NUM>, to move the derailleur or decouple the transmission from the derailleur as will be explained in more detail below.

As shown in <FIG> (which is section E-E of <FIG>), a biasing spring <NUM> is disposed around one of the linkage pivot pins 28b. One leg 54a of the biasing spring <NUM> engages the outer link <NUM>, and the other leg (not shown) engages the base member <NUM>. The biasing spring <NUM> may be an extension spring <NUM>' (<FIG>). The action of the biasing spring <NUM> urges the linkage <NUM> in the outboard direction to take the backlash out of the gearbox <NUM> and linkage.

<FIG> (which is section B-B of <FIG>) shows the low limit screw <NUM>. The low limit screw <NUM> is disposed in the gearbox assembly <NUM>, and by advancing and retracting the screw the inboard range of motion of the inner link <NUM> is limited. The limit screw <NUM> is adjusted in a tool-free manner, by turning the limit screw <NUM> by hand. This tool-free design greatly reduces the maximum torque that the limit screw <NUM> sees since the human hand can exert a lot less torque on the screw than a human hand aided by a screwdriver or other tool, and therefore greatly limits the force exerted on the gears (see <FIG>) of the gearbox <NUM> by the limit screw. This is desirable because excessive force on the gears could break them.

<FIG> is an exploded view of the gearbox assembly <NUM>. The gearbox assembly <NUM> may form the structural part of the b-knuckle <NUM>. As shown in <FIG>, a motor module <NUM> (described in detail later) is received in an opening <NUM> in the bottom of the housing <NUM> of the gearbox <NUM> and is secured with fasteners <NUM>, for example, six screws. The housing <NUM> includes a pogo pin/seal assembly <NUM> (described in detail below) received in a recess <NUM> in the rear wall <NUM> of the gearbox housing <NUM> and is secured with fasteners <NUM>, for example, two screws.

An overview of the motor module <NUM> is shown in <FIG>. A motor <NUM> is attached to a motor module base <NUM>, which may be a plastic injection-molded element or elements of any suitable material, and the majority of the transmission <NUM> is built up on axles <NUM> that are received in the base <NUM>. A plate <NUM>, which may be stamped metal or any suitable material, is attached to the base <NUM>, by screws for example, and supports the other end of the axles <NUM> of one or more of the gears, for example three of the gears.

The gearbox <NUM> includes a position detector <NUM> (see <FIG>, <FIG>). Gears associated with the position detector, which will be described in more detail hereinbelow, are located on or near the motor module base <NUM>. PC boards <NUM> comprising circuitry for operating various functions of the derailleur <NUM> are connected together by flexible cables <NUM>. The PC boards <NUM> may be three rigid boards or any suitable number of boards. Two of the three PC boards <NUM> may be screwed to the base <NUM>, and the other PC board may be soldered to the back of the motor <NUM>, for example. A flexible seal <NUM> is provided on the base <NUM> to seal between the base and a motor module housing <NUM> after the base is assembled to the motor module housing.

<FIG> is a section view of the motor module <NUM>, showing a cross section of the motor <NUM> (section H-H of <FIG>). Referring to <FIG>, the motor <NUM> may be attached to the motor module base <NUM> with two screws (not visible in this view). A worm <NUM> is fixed to a shaft <NUM> of the motor <NUM>, and a distal end <NUM> of the motor shaft is received in a bearing <NUM>, such as a ball bearing, which is, in turn, received in the motor module base <NUM>. A worm wheel <NUM> is engaged with the worm <NUM>.

<FIG> is a section view of the gearbox <NUM>, showing three of the gear assemblies (section K-K of <FIG>). Referring to <FIG>, one end of each of the three axles <NUM> may each be rotatably received in the motor module base <NUM>, and the other end of each axle is received in a corresponding hole in the previously discussed metal plate <NUM>. Three gear assemblies 106a-c of the transmission <NUM> are rotatably received on the three axles <NUM>, respectively. The gear assembly 106a on the right in <FIG> has the worm wheel <NUM> on the bottom. The worm wheel <NUM>, as discussed earlier, is engaged with the worm <NUM> on the motor shaft <NUM> (see <FIG>). The worm wheel <NUM> is rigidly attached to a first pinion gear <NUM> that is coaxial therewith. The first pinion gear <NUM> is engaged with a spur gear <NUM> that is rotatably received on the middle of the three axles 82b. This spur gear <NUM> is rigidly attached to a second pinion gear <NUM> that is coaxial therewith. The second pinion gear <NUM> is engaged with a second spur gear <NUM> that is rotatably received on the axle 82c shown on the left in <FIG>. The second spur gear <NUM> is rigidly attached to a third pinion gear <NUM> that is coaxial therewith. The third pinion gear <NUM> is engaged with an output gear <NUM> (see <FIG>) of the gearbox <NUM> (not visible in this section view). It should also be noted that the axle 82c shown on the left in <FIG> has its top end supported in a bearing <NUM> in the motor module housing <NUM>, which adds a substantial amount of support to the metal plate <NUM>. In other words, the metal plate <NUM> is supported by the leftmost axle 82c, which in turn is supported by the bearing <NUM> in the motor module housing <NUM>.

<FIG> is a section view of the derailleur <NUM>, showing a cross section of the two linkage pivot pins 28a, b located by the b-knuckle <NUM> (section E-E of <FIG>). Referring to the right hand side of <FIG>, the output gear <NUM> of the gearbox <NUM> has a toothed portion <NUM> and two tubular portions 124a, b projecting from either side of the toothed portion. The lower tubular portion 124a is rotatably received in a bearing in the motor module base <NUM>, and the upper tubular portion 124b is rotatably received in a bearing in the motor module housing <NUM>. The end of the lower tubular portion 124a has the aforementioned castellated geometry that engages the drive arm <NUM> as previously described (see <FIG>). The inner link <NUM> has two arms 126a, b, one of which is located above the upper tubular portion 124b of the output gear <NUM>, and the other of which is located below the lower tubular portion 124a of the output gear. A hole <NUM> in the inner link arms 126a, b is coaxial with a hole <NUM> in the output gear <NUM>, and the associated link pin 28a is received in these holes. The link pin 28a is rotatable relative to the output gear <NUM>, but is preferably rotatably fixed to the inner link <NUM>.

<FIG> is a section view of the gearbox <NUM>, showing a cross section of the position detector <NUM>. The position detector <NUM> is used to determine the position of the derailleur by sensing rotation of the transmission <NUM> (see <FIG>). The position detector <NUM> includes a sensor in the form of a position detector chip <NUM>, a position detector gear <NUM>, a position detector magnet <NUM>, and an optional position detector gear biasing gear <NUM> (section J-J of <FIG>). Referring to <FIG>, the position detector gear <NUM> is rotatably mounted on a position detector axle <NUM>, which is supported by the motor module base <NUM>. The position detector gear <NUM> engages the output gear <NUM>. A magnet holder <NUM> is fixed to the position detector gear <NUM>, and the position detector magnet <NUM> is fixed to the magnet holder. Thus, the position detector gear <NUM>, magnet holder <NUM>, and magnet <NUM> all rotate together as a unit.

A position detector gear biasing gear axle <NUM> is supported by the motor module base <NUM>. The position detector gear biasing gear <NUM> is rotatably received on the position detector gear biasing gear axle <NUM>. One leg of a torsion spring <NUM> is engaged with the motor module base <NUM>, and the other leg of the torsion spring is engaged with the position detector gear biasing gear <NUM>. Thus, the torsion spring <NUM> exerts a torque on the position detector gear biasing gear <NUM>, which in turn exerts a torque on the position detector gear <NUM> to effectively eliminate any play or backlash between the position detector gear and the output gear <NUM>.

<FIG> is a section view of the motor module <NUM>, showing a cross section of the means by which the position detector chip <NUM> is accurately located relative to the position detector magnet <NUM> (section G-G of <FIG>). Referring to <FIG>, a position detector chip <NUM> is disposed on one of the three PC boards <NUM>. A magnet guide <NUM> has two projections <NUM>, which may be cylindrical, and which fit into two corresponding holes <NUM> in the PC board <NUM>. Two fasteners, e.g., screws, are inserted into the projections <NUM> to fasten the magnet guide <NUM> in place on the PC board <NUM>. Thus, the PC board <NUM>, position detector chip <NUM>, magnet guide <NUM>, and two screws form a subassembly. During assembly of the motor module <NUM>, this subassembly is assembled to the motor module such that the magnet <NUM> is received in the magnet guide <NUM>. Thus, the axis of the position detector chip <NUM> is accurately aligned to the axis of the position detector magnet <NUM>.

In order to prevent rotation of the PC board <NUM> relative to the motor module <NUM>, a slot <NUM> in the other end of the PC board engages a boss <NUM> on the motor module base <NUM> (see <FIG>). Again referring to <FIG>, a screw <NUM> is then screwed into a hole in the boss <NUM> until the screw bottoms out on the boss. In this manner, the alignment between the position detector chip <NUM> and the position detector magnet <NUM> is held very accurately. An optional compression spring <NUM> biases the PC board assembly <NUM> downwards in <FIG>. Alternatively, the magnet guide <NUM> could have geometry that locates directly on the position detector chip <NUM>, rather than locating in two holes <NUM> in the PC board <NUM>.

<FIG> is a section view of the gearbox <NUM>, showing a cross section of a button <NUM> and its actuator assembly <NUM> (section A-A of <FIG>). The button <NUM> may be an electrical component on the PC board <NUM>. The actuator assembly <NUM> includes a plunger <NUM>, return spring <NUM>, O-ring seal <NUM>, and retaining clip <NUM>. When the plunger <NUM> is pressed by the user, it actuates the button <NUM>. Also visible towards the bottom of <FIG> is an LED <NUM>, which is another component on the PC board <NUM>. This LED <NUM> shines through a clear lens <NUM> (also partially visible in <FIG>) in the motor module base <NUM>.

<FIG> show the derailleur <NUM> with a power source <NUM>, which may be a battery, installed (<FIG>) and with the power source removed (<FIG>). The cage assembly is omitted in these views for clarity. The battery may be a rechargeable battery and may be of the lithium-polymer variety.

<FIG>, <FIG>, <FIG> (section D-D of <FIG>) show the electrical and mechanical connectivity between the battery <NUM> and the derailleur <NUM>, and also show the procedure for removing the battery from the derailleur. Referring to <FIG>, <FIG>, <FIG>, and <FIG>, the pogo pin assembly <NUM> includes a pogo pin base <NUM>, a pogo pin base seal member <NUM>, and two pogo pins <NUM> (only one visible), two return springs <NUM> (one visible), and two O-rings <NUM> (one visible). The pogo pin assembly <NUM> may be attached to the motor module housing <NUM> with two screws as shown in <FIG>. Referring to <FIG>, <FIG>, <FIG>, one end of the return springs <NUM> contacts the pogo pin <NUM>, and the other end of the return springs contacts electrical contact pads <NUM> (<FIG>) on a PC board <NUM>. Thus, when the battery <NUM> is installed as shown in <FIG>, electricity can flow from the battery, through the pogo pin <NUM>, through the return spring <NUM>, and into the PC board <NUM>. The power supply <NUM> may be mechanically retained on the derailleur <NUM> with a catch <NUM>.

Turning to <FIG>, and also <FIG>, the derailleur <NUM> is equipped with a breakaway mechanism or clutch <NUM> that protects the gears <NUM> of the transmission <NUM> in the gearbox <NUM> (<FIG>) in the event of a crash or other side impact to the derailleur. <FIG>, <FIG> and <FIG>, show a section view of the derailleur <NUM> (section C-C of <FIG>) with the clutch <NUM> in its non-actuated (i.e. normal) position (<FIG>), its partially actuated position (<FIG>), and its fully actuated position (<FIG>). During normal riding, the elements of the clutch <NUM> are arranged as shown in <FIG>, comprising the spring <NUM> and drive arm <NUM>.

In the event of a crash or other side impact (a force directed from left to right in <FIG>, <FIG> and <FIG>), if the force of the impact overcomes the preload in the torsion-type clutch spring <NUM>, the links of the linkage <NUM> rotate clockwise about their pivot pins <NUM>, deflecting the leg 52a of the spring as shown in <FIG>. Thus, the linkage <NUM> is able to move without imparting any movement to the gears <NUM> in the gearbox <NUM>. When the impact force is removed from the derailleur <NUM>, the spring leg 52a will push against the drive arm <NUM> and cause the derailleur to go back to its normal state shown in <FIG>.

In the event of a more forceful crash or side impact, the links of linkage <NUM> can rotate clockwise about their pivot pins <NUM> all the way to the position shown in <FIG>. In this position, further clockwise rotation of the links <NUM> is prevented when the drive arm <NUM> and projection <NUM> interact and any additional force imparted to the links will be transferred to the gears <NUM>.

Another aspect of the invention that protects the gears <NUM> is the straight-P arrangement of the derailleur <NUM>. When a bicycle is moving over rough terrain, the p-knuckle <NUM> of the derailleur <NUM> experiences forces in the vertical direction. In a slant P derailleur, the axes of the link pins are angled relative to the vertical direction, and these forces can be transmitted through the linkage/parallelogram, imparting undesired forces to the gears in the transmission, since the linkage is able to move in a direction that has a substantial vertical component. The motion of the linkage <NUM> of the present invention, however, is substantially lateral, rather than vertical, at least because of the vertical orientation of the link pins <NUM>, and therefore the elements of the derailleur are relatively isolated from the vertical forces created when the bicycle is moving over rough terrain, thereby protecting the gears <NUM> of the transmission <NUM> from damage. Preferably, the axes of the link pins <NUM> are all within <NUM> degrees of vertical (in addition to being normal to the axial A' direction).

A radio chip <NUM> is positioned on the PC board <NUM> in such a way to maximize radio signals transmitted between the derailleur <NUM> and a shifter (or other control devices). Referring to <FIG>, the radio chip <NUM> is positioned on the lower portion of the rightmost PC board <NUM> such that it is substantially housed in the motor module base <NUM>, which may be made of plastic, or any suitable material that does not interfere with the transmission of radio signals. In other words, the radio chip <NUM> is preferably not positioned on the upper portion of the PC board <NUM>, because the upper portion of the PC board is substantially housed in the motor module housing <NUM>, which is preferably made of aluminum, which is a material that is not conducive to transmitting radio signals.

Claim 1:
An electromechanical rear derailleur (<NUM>) for a bicycle, comprising:
a base member (<NUM>) attachable to the bicycle along a mounting axis (A');
a movable member (<NUM>) having a cage (<NUM>) assembly attached thereto;
a linkage (<NUM>) including pivot axes (PA) oriented perpendicular to the mounting axis (A'),wherein the linkage (<NUM>) includes an outer link member (<NUM>) and an inner link member (<NUM>), and couples the movable member (<NUM>) to the base member (<NUM>) and is operative to enable movement of the movable member (<NUM>) relative to the base member (<NUM>);
a power source (<NUM>),
a motor (<NUM>) electrically connected to the power source (<NUM>); and
a transmission (<NUM>) coupled to and actuated by the motor (<NUM>) to move the movable member (<NUM>), characterized in that the power source (<NUM>) is disposed on the base member (<NUM>) opposite to the linkage (<NUM>) and the movable member (<NUM>).