front derailleur

Abstract

Front derailleur (12) for mounting on a bicycle (10) having a pedal crank axle (A1), the front derailleur (12) comprising: a base member (40) adjustably mounted to the bicycle (10) in a predetermined adjustment direction (D); a chain guide (42) for guiding a chain (36); and a linking mechanism (44) for movably coupling the chain guide (42) to the base member (40), the linking mechanism (44) including a first linking link (66) pivotable with respect to the base member (40) about a first linking axis (70) and pivotable with respect to the chain guide (42) about a second linking axis (72), the first linking axis (70) and the second linking axis (72) being arranged non-parallel and non-orthogonal to the predetermined adjustment direction (D) as viewed from the axial direction of the crank axle (A1) in a state in which the base member (40) is mounted to the bicycle (10), the first linking axis (70) and the second linking axis (72) being inclined with respect to the predetermined adjustment direction (D) within a range of 20 to 25 degrees.

Description

This application claims priority to Japanese Patent Application No. 2013-145425 filed on Jul. 11, 2013. The entire disclosure of Japanese Patent Application No. 2013-145425 is hereby incorporated herein by reference.The present invention relates to a derailleur, more specifically to a front derailleur that can be mounted to a bicycle having a crank axle.Basically, a front derailleur includes a base member for mounting the front derailleur to the frame of a bicycle, a chain guide for guiding a chain, and a link mechanism for movably coupling the chain guide to the base member. In this conventional front derailleur, the base member is mounted to a seat tube to be / be positioned in an adjustment direction which is along the axial direction of the seat tube. The link mechanism includes two link members arranged in parallel. The link members are coupled to the chain guide and to the base member via a link shaft near the chain guide and a link shaft near the base member. Finally, in the conventional front derailleur, the link shafts are arranged to extend in a direction parallel to or in a direction orthogonal to the adjusting direction of the base member. Such a front derailleur is known from, for example, Japanese Utility Model Laid-Open Publication No. JP S57-57,194 U or Japanese Patent Laid-Open Publication No. 2007-186,176 A.German patent application DE 10 2014 106 893 A1 describes a switching mechanism comprising a base element, a movable element, a connecting element and a pretensioning mechanism. The movable member is configured to be movable relative to the base member between a retracted position and an extended position.U.S. patent application US 2014 / 0 349 793 A1 describes a front derailleur having a base member, a chain guide, a link mechanism and a cable guide structure. The base member is fixedly coupled to a bicycle. The chain guide is configured to guide a chain.DE 37 21 617 A1 discloses a front derailleur for a bicycle provided with a link mechanism having a mounting part, first and second link parts pivotally supported on the mounting part, first and second pivot pins by which the first and second link parts are pivotally supported on the mounting part, a movable part pivotally supported on the link part and having a chain guide, and third and fourth pivot pins by which the link parts are pivotally supported on the movable part, wherein the first link part is provided with an operating arm for deforming the link mechanism upon operation.US 4 424 048 A discloses a front derailleur for a bicycle comprising a base member provided with a horizontal bracket and a pair of link members arranged in the longitudinal direction of the bicycle and extending horizontally, the link members being pivotally mounted to the bracket by first and second pivot shafts extending vertically so that an air resistance against the link members is reduced during running of the bicycle and a uniform speed can be achieved.Substantially, the moving direction of the chain (chain line) is not parallel and not orthogonal to the link shafts. In this type of configuration, the portion near the front part of the base member hangs above the chain line. In other words, the front derailleur is larger in effect.The object of the present invention is to design a more compact front derailleur.The front derailleur according to the present invention is for mounting to a bicycle having a crank axle. The front derailleur is provided with a base member, a chain guide, and a link mechanism. The base member is adjustably adjustable to the bicycle in a predetermined adjustment direction. The chain guide guides a chain. The link mechanism movably couples the chain guide to the base member; the link mechanism includes a first link member that is pivotable with respect to the base member about a first link axis and that is pivotable with respect to the chain guide about a second link axis. The first link axis and the second link axis are arranged non-parallel and non-orthogonal to the predetermined adjustment direction, as viewed from the axial direction of the crank axis, in the use state in which the base member is mounted on the bicycle, wherein the first link axis and the second link axis are inclined with respect to the predetermined adjustment direction within a range of 20 to 25 degrees.In this type of front derailleur, the first link axis and the second link axis are arranged non-parallel and non-orthogonal to the predetermined adjustment direction, and thus the front part of the base member can be made more compact along the chain line. As a result, this makes it possible to make the entire front derailleur more compact.The first link axis and the second link axis may be inclined with respect to the predetermined adjustment direction within a range of 30 degrees. In this case, it is possible to make the first link axis and the second link axis substantially orthogonal to the chain line, and the front derailleur can be made compact more effectively.The first connecting axis and the second connecting axis can be arranged parallel to one another. In this case, the chain guide smoothly moves due to the link member.The linkage mechanism may further include a second link that is pivotable with respect to the base link about a third link axis and that is pivotable with respect to the chain guide about a fourth link axis. The third link axis and the fourth link axis may be arranged non-parallel and non-orthogonal with respect to the predetermined adjustment direction as viewed from the axial direction of the crank axis in the use state in which the base member is mounted on the bicycle. In this case, the base member, the first link member, the second link member, and the chain guide form a four-bar linkage that more stably and movably supports the chain guide.The first link axis, the second link axis, the third link axis, and the fourth link axis may be arranged parallel to each other. In this case, the four-bar linkage stabilizes the chain guide to allow the chain guide to move smoothly.The front derailleur according to another aspect of the present invention is mounted on a bicycle having a rear hub axle, a crank axle, and a chainring for rotating about the crank axle. The front derailleur is provided with a base member, a chain guide, and a link mechanism. The base member is for mounting to the bicycle. The chain guide guides a chain. The link mechanism movably couples the chain guide to the base member; the link mechanism includes a first link member pivotable with respect to the base member about a first link axis and pivotable with respect to the chain guide about a second link axis. The first link axis and the second link axis are arranged to be / are inclined with respect to a first plane within a range of 85 to 95 degrees in the driving rotational direction of the chainring in a state where the base member is mounted on the bicycle, the first plane including the rear hub axis and the crank axis.In this type of front derailleur, the first link axis and the second link axis are arranged inclined with respect to the first plane within a range of 85 to 95 degrees in the driving rotational direction of the chainring, in which the first plane includes the rear hub axis and the crank axis, and therefore the front part of the base link along the chain line can be made more compact. As a result, this makes it possible to make the entire front derailleur more compact.The first connecting axis and the second connecting axis can be arranged parallel to one another. In this case, due to the link, the chain guide can move smoothly.The linkage mechanism may further include a second link that is pivotable with respect to the base link about a third link axis and that is pivotable with respect to the chain guide about a fourth link axis. The third link axis and the fourth link axis are arranged to be / are inclined with respect to a first plane within a range of 80 to 100 degrees in the driving rotational direction of the chainring in a state where the base member is mounted on the bicycle. In this case, the base member, the first link member, the second link member, and the chain guide form a four-bar linkage that more stably and movably stabilizes the chain guide.The first link axis, the second link axis, the third link axis, and the fourth link axis may be arranged parallel to each other. In this case, the four-bar linkage stabilizes the chain guide to allow the chain guide to move smoothly.The link mechanism may be configured such that an operation cable is attachable to the link mechanism, and the base member may include a cable guiding structure for guiding the operation cable forward. In this case, the operating cable actuates the connecting element.The cable guide structure may be configured such that the operation cable extends from a second plane orthogonal to the first plane within a range of 150 degrees in the driving rotational direction of the chainring. In this case, the direction in which the operation cable extends intersects the first link axis and the second link axis, and thereby the operation cable is allowed to effectively operate the first link member.A more compact front derailleur can be designed. FIG. 1 is an exploded right side view of a bicycle equipped with a front derailleur according to a first embodiment of the present invention; FIG. 2 is a right side view of the front derailleur according to the first embodiment of the present invention; FIG. 3 is a left side view of the front derailleur according to the first embodiment of the present invention; FIG. 4 is a cross-sectional view of the front derailleur taken along the section line IV-IV of FIG. 2 ; and FIG. 5 is an exploded right side view of the bicycle equipped with a front derailleur illustrating the relationship between a first plane and a link axle.Preferred embodiments of the invention will now be described in detail.In FIG. 1, a bicycle 10 according to the embodiment of the present invention is provided with a frame 14 including a seat tube 34, a crank axle A 1, a rear hub axle A 2, and a front derailleur 12. The crank axle A 1 and the rear hub axle A 2 are arranged parallel to each other. The front derailleur 12 is mounted to the seat tube 34 of the frame 14 in a detachable and reinstallable manner. A shifting operation is performed by the front derailleur 12 by an operating device mounted on a handlebar of the bicycle 10 through an operating cable 30 (the operating device and the handlebar are not illustrated in the drawings). The operation cable 30 includes an outer sheath 30 aand an inner cable 30 bextending through the outer sheath 30 a. The control cable 30 is a conventional Bowden cable. The inner cable 30b is slidably inside the outer sheath 30a. For example, the control cable 30 is disposed within a downpipe 32 of the frame 14. The operation cable 30 is then taken from the inside of the downpipe 32 to the center and coupled to the front derailleur 12. Here, the terms "front", "rear", "left", "right", "up" and "down", and synonyms thereof refer to "front", "rear", "left", "right", "up" and "down" as viewed from a rider who sits on a saddle and faces a handlebar (both are not illustrated in the drawings).The front derailleur 12 is mounted to the seat tube 34 in the illustrated embodiment. However, the front derailleur 12 may be mounted at a suitable location other than the seat tube, such as a bracket tube (bottom bracket tube) 38 or the like. The pedal crank axis A 1 is defined by means of the bracket tube 38. More specifically, the crank axis A 1 corresponds to a central longitudinal axis of the bracket tube 38. The rear hub axle A 2 is defined by a center axis of a rear hub (rear wheel) which is not illustrated in the drawings. Thus, the rear hub axle A 2 is the center of rotation of the rear hub.The front derailleur 12 is configured so that the operating cable 30 exits the front derailleur 12 forward along a cable axis A 3. The cable axis A 3 extends forward in a driving rotational direction (illustrated by the arrow B in FIG. 1 ) of the crawler blades 28 a, 28 b, and 28 cin the range of an angle α 1 from a second plane P 2 that is perpendicular to a first plane P 1 including the rear hub axis A 2 and the pedal crank axis A 1. Here, the angle α 1 is 150 degrees. The "driving rotational direction" refers to a rotational direction of the link plates 28 a, 28 b, and 28 cto drive a chain 36 in an arrow direction C as described below. In other words, the "driving rotational direction" refers to a rotational direction of the crawler blades 28 a, 28 b, and 28 cto move the bicycle 10 forward.As illustrated in FIG. 2, the front derailleur 12 includes a base member 40, a chain guide 42, a link mechanism 44, and a chain guide structure 46. the base member 40 is configured to be / be fixed to the bicycle 10 in a detachable and re-installable manner. The chain guide 42 is configured to guide the chain 36. The linkage mechanism 44 movably couples the chain guide 42 to the base member 40. for example, the linkage mechanism 44 movably couples the chain guide 42 to the base member 40 between a retracted position proximate the frame 14, an extended position away from the frame 14 as compared to the retracted position, and an intermediate position located between the retracted position and the extended position in response to movement of the inner cable 30 b. More specifically, the chain guide 42 is moved with respect to the base member 40 in a direction away from the frame 14 by the pulling of the inner cable 30 b. The chain guide 42 is moved with respect to the base member 40 in a direction close to the frame 14 by releasing the inner cable 30 b. In this way, the chain guide 42 guides the chain 36 to each of the chain sheets 28 a, 28 b, and 28 cin response to the operation of the operating device, which is not illustrated in the drawings.The base member 40 is mounted to the seat tube 34 over the chain guide 42 for positioning on the seat tube. The base member 40 is positionable along a central axis D 1 of the seat tube 34 illustrated in FIG. 1 in a predetermined adjustment direction D. As illustrated in FIGS. 2 and 3, in this embodiment, the base member 40 is configured as a band clamp that clamps the seat tube 34.As further illustrated in FIGS. 2 and 3, the base member 40 includes a first clamping part 50, a second clamping part 52, and a connecting part 54. A hinge pin 55 couples a first end part of the first clamping part 50 and a first end part of the second clamping part 52 to pivot with respect to each other. A second end part of the first clamping part 50 and a second end part of the second clamping part 52 are fastened by a fastening member 56 consisting of a bolt and the like. The tightening member has a shaft portion forming the screw thread. The shaft portion of the fastening member 56 is inserted through a through hole in the second clamping part 52 and screwed into a screw hole provided in the first clamping part 50. At this time, the second end part of the first clamping part 50 and the second end part of the second clamping part 52 are brought together so that the first clamping part 50 and the second clamping part 52 clamp the seat tube 34, and thus the base member 40 is secured to the seat tube 34. The connection part 54 is provided to extend rightward and then forward from the first clamping part 50. The lower front end part of the connection part 54 is provided with a LoW position adjustment screw 58 aand a top position adjustment screw 58 b. The low position adjustment screw 58 ais provided to adjust the retracted position of the chain guide 42. The top position adjustment screw 58 bis provided to adjust the extended position of the chain guide 42.As illustrated in FIGS. 2 and 3, the chain guide 42 includes a first guide plate (outer / right side guide plate) 60 and a second guide plate (inner / left side guide plate) 62, A chain slot S through which the chain 36 passes is formed between the first guide plate 60 and the second guide plate 62, which are arranged to oppose each other in a lateral direction (horizontal direction). As described above, the chain guide 42 is movably coupled to the base member 40 by the link mechanism 44 between the retracted position and the extended position. The chain guide 42 has an upstream end 42 aand a downstream end 42 band a downstream end 42 b. The terms "upstream" and "downstream" as used herein mean with respect to the direction of travel of the chain 36 during pedaling. For example, in FIG. 1, the chain 36 moves in the direction of arrow C during pedaling. Therefore, the left side in FIG. 1 is upstream and the right side in FIG. 1 is downstream. The first guide plate 60 is bent at the upstream end 42 ato extend toward the second guide plate 62, and is coupled to the second guide plate 62 by a rivet 64. Also, the first guide plate 60 and the second guide plate 62 are integrally coupled to each other at the downstream end 42 bof a coupling portion extending in the lateral direction (horizontal direction). The first guide plate 60 contacts an outer surface of the chain 36 and moves in a leftward lateral direction toward the bicycle frame 14 so that the chain 36 moves toward the retracted position. The second guide plate 62 contacts an inner surface of the chain 36 and moves in a rightward lateral direction away from the frame 14 such that the chain 36 moves toward the extended position.As shown in FIG. 4, the link mechanism 44 includes a first link 66 and a second link 68, and is configured as a four-bar linkage mechanism together with the base member 40 and the chain guide 42. The first link 66 pivots about a first link axis 70 with respect to the base member 40 and pivots about a second link axis 72 with respect to the chain guide 42. The second link member 68 pivots about a third link axis 74 with respect to the base member 40 and pivots about a fourth link axis 76 with respect to the chain guide 42. Furthermore, the first link axis 70, the second link axis 72, the third link axis 74, and the fourth link axis 76 are arranged parallel to each other. The first link shaft 70, the second link shaft 72, the third link shaft 74, and the fourth link shaft 76 are arranged substantially vertically in a state where the front derailleur 12 is arranged on the bicycle 10. Further, the first link 66 is disposed at a position closer to the frame 14 than the second link 68 (disposed on the left side) in a state where the front derailleur 12 is disposed to the bicycle 10.The first link 66 includes a cable mounting part 66 a. The inner cable 30 bis clamped by the cable mounting part 66 a, and a head of a bolt 78 is screwed into the cable mounting part 66 a, and the inner cable 30 bis fixed to the first link member 66. The chain guide structure 46 is configured to guide the operating cable 30 from the cable mounting part 66 atoward a front side of the bicycle 10 with respect to the downstream end 42 bof the chain guide 42. The chain guide structure 46 is disposed in at least one of the base member 40 and the link mechanism 44 as explained below. In any case, it is preferable that the operation cable 30 is guided to a position farther forward, as compared with a conventional chain guide structure in which the operation cable 30 is guided upward or downward along the seat tube 34.The chain guide structure 46 includes a first chain guide part 80 formed on the base member 40 and a second chain guide part 82 formed on the link mechanism 44. The first chain guide part 80 is provided as a through hole in the connecting part 54 of the base member 40, while the second chain guide part 82 is provided as a through hole on the first link member 66. An insertion sleeve 84 is mounted in the first chain guide part 80 to improve the sliding performance of the inner cable 30 b. Finally, the first link 66 includes a protruding portion 86 extending to the right side, and the second chain guide part 82 is provided in the protruding portion 86.The linkage mechanism 44 further includes a biasing member 88. the biasing member 88 biases the chain guide 42 in a retracted position or an extended position. In the illustrated embodiment, the biasing member 88 is a torsion coil spring that biases the chain guide 42 in the retracted position. The biasing member 88 is disposed coaxially with the second link shaft 72.The first link axis 70, the second link axis 72, the third link axis 74, and the fourth link axis 76 are arranged non-parallel to and non-orthogonal to the predetermined adjustment direction D as viewed from the axial direction of the crank axis A 1 in the use state in which the base member 40 is mounted on the frame 14. In this embodiment, the first link axis 70, the second link axis 72, the third link axis 74, and the fourth link axis 76 (only the second link axis 72 is illustrated in FIG. 1 ) are each provided to fall within a range α 2 of 30 degrees of the predetermined adjustment direction D as viewed from the axial direction of the crank axis A 1. That is, more specifically, the first link axis 70, the second link axis 72, the third link axis 74, and the fourth link axis 76 are each provided to fall within a range of 20 degrees to 25 degrees. In addition, the "use state" corresponds to a state in which the front derailleur 12 is appropriately mounted on the bicycle 10 to use it for shifting gears.For a front derailleur 12 configured in this manner, as soon as the inner cable of the operating cable 30 pulls in the front derailleur 12 as described above, the chain guide 42 moves in a direction away from the frame 14 and the chain guide 42 moves with respect to the base member 40 toward the large-diameter chainring. At this time, the shape of the front portion of the base member 40 along the track of the chain 36 (chain line) shown by the dotted line in FIG. 1 can be made more compact due to the above arrangement of the first link shaft 70, the second link shaft 72, the third link shaft 74, and the fourth link shaft 76. As a result, this allows the entire front derailleur 12 to be made more compact.In addition, as illustrated in FIG. 5, the first link axis 70 and the second link axis 72 are disposed at an angle α 3 of 80 degrees to 100 degrees with respect to the first plane P 1 in a use state in which the base member 40 is mounted on the bicycle 10. That is, the first link axis and the second link axis are disposed inclined with respect to the first plane within a range of 80 to 100 degrees in the driving rotational direction B of the crawler blades 28 a, 28 b, and 28 cin which the first plane includes the rear hub axis A 2 and the crank axis A 1. The range of the angle α 3 may preferably be set from 85 degrees to 95 degrees. The third link axle 74 and the fourth link axle 76 are configured in the same manner.The shape of the front portion of the base member 40 can be made more compact along the track of the chain 36 (chain line) shown by the dotted line in FIG. 5 also with this configuration. As a result, this allows the entire front derailleur to be made more compact.This concludes the description of an embodiment of the present invention. However, the present invention is not limited to the above-described embodiment and may be modified in various ways as long as the modifications remain within the spirit and scope of the invention. More specifically, the embodiments and modification examples in this specification can be arbitrarily combined as necessary.(a) In the above-mentioned embodiment, the link shafts are arranged to extend substantially vertically when the front derailleur is mounted to the bicycle, but the link shafts may be arranged to extend substantially horizontally when the front derailleur is mounted to the bicycle.(b) In the above-mentioned embodiment, the chain guide 42 moves to one of three positions. However, the chain guide 42 may be configured to move to two positions, the retracted position and the extended position.(c) In the above-mentioned embodiment, the base member 40 is a band clamp. However, the present invention is not limited to this setting. The base member may be fixedly secured to the seat tube and the like threadably secured to the frame in a bore; and the base member may also be secured to the bottom bracket.(d) In the above-mentioned embodiment, a front derailleur is described which is operated by using an operation cable. However, the present invention is not limited to this setting. An electrically operated front derailleur can also be adapted in the present invention.(e) The first link axis and the second link axis do not need to have the same inclination angle. In addition, the third link axis and the fourth link axis do not need to have the same inclination angle. More specifically, for a four-bar linkage, the first link axis and the third link axis may have the same inclination angle, while the second link axis and the fourth link axis have the same inclination angle.Reference numerals denote reference numerals10 Bicycle 12 Front derailleur 28 a, 28 b, 28 c Ketten 36 Chain 40 Base link 42 Chain guide 44 Link mechanism 46 Chain guide structure 66 First link link 68 Second link link 70 First link axle 72 Second link axle 74 Third link axle 76 Fourth link axle A 1 Crank axle A 2 Rear hub axle B Driving rotational direction D Predetermined adjustment direction P 1 First plane P 2 Second plane

Claims

A front derailleur (12) for mounting to a bicycle (10) having a crank axle (A1), the front derailleur (12) comprising: a base member (40) adjustably mounted to the bicycle (10) in a predetermined adjustment direction (D); a chain guide (42) for guiding a chain (36); and a link mechanism (44) for movably coupling the chain guide (42) to the base member (40), the link mechanism (44) including a first link member (66) that is pivotable with respect to the base member (40) about a first link axis (70) and that is pivotable with respect to the chain guide (42) about a second link axis (72), the first link axis (70) and the second link axis (72) being arranged non-parallel and non-orthogonal to the predetermined adjustment direction (D) as viewed from the axial direction of the crank axis (A1) in a state where the base member (40) is mounted to the bicycle (10), the first link axis (70) and the second link axis (72) being inclined with respect to the predetermined adjustment direction (D) within a range of 20 to 25 degrees.Front derailleur (12) according to claim 1, wherein the first connecting axis (70) and the second connecting axis (72) are arranged parallel to one another.The front derailleur (12) according to claim 1, wherein the link mechanism (44) further includes a second link (68) that is pivotable with respect to the base link (40) about a third link axis (74) and that is pivotable with respect to the chain guide (42) about a fourth link axis (76), and wherein the third link axis (74) and the fourth link axis (76) may be arranged non-parallel and non-orthogonal with respect to the predetermined adjustment direction (D) as viewed from the axial direction of the crank axis (A1) in a state where the base link (40) is mounted to the bicycle (10).Front derailleur (12) according to claim 3, wherein the first link axis (70), the second link axis (72), the third link axis (74) and the fourth link axis (76) are arranged parallel to one another.A front derailleur (12) for mounting to a bicycle (10) having a rear hub axle (A2), a crank axle (A1), and a chainring (28a; 28b; 28c) for rotating about the crank axle (A1), the front derailleur (12) comprising: a base link (40) for mounting to the bicycle (10); a chain guide (42) for guiding a chain (36); a link mechanism (44) for movably coupling the chain guide (42) to the base link (40), wherein the link mechanism (44) includes a first link (66) that is pivotable with respect to the base link (40) about a first link axis (70) and that is pivotable with respect to the chain guide (42) about a second link axis (72); and the first link shaft (70) and the second link shaft (72) are arranged to be / inclined with respect to a first plane (P 1) within a range of 85 to 95 degrees in a driving rotational direction (B) of the chainring (28 a; 28 b; 28 c) in a state where the base member (40) is mounted to the bicycle (10), wherein the first plane (P 1) includes the rear hub shaft (A 2) and the crank shaft (A 1).Front derailleur (12) according to claim 5, wherein the first connecting axis (70) and the second connecting axis (72) are arranged parallel to one another.The front derailleur (12) according to claim 5, wherein the link mechanism (44) further includes a second link (68) that is pivotable with respect to the base link (40) about a third link axis (74) and that is pivotable with respect to the chain guide (42) about a fourth link axis (76); and the third link axis (74) and the fourth link axis (76) are arranged to be / are inclined with respect to the first plane (P1) within a range of 80 to 100 degrees in the driving rotational direction (B) of the chainring (28a; 28b; 28c) in a state where the base link (40) is mounted to the bicycle (10).Front derailleur (12) according to claim 7, wherein the first link axis (70), the second link axis (72), the third link axis (74) and the fourth link axis (76) are arranged parallel to one another.The front derailleur (12) for use with a bicycle (10) according to any one of claims 5 to 8, wherein the link mechanism (44) is configured such that an operating cable (30) is attachable to the link mechanism (44); and the base member (40) includes a cable guiding structure for guiding the operating cable (30) forward.The front derailleur (12) according to claim 9, wherein the cable guide structure is configured such that the operation cable (30) extends from a second plane (P2) orthogonal to the first plane (P1) within a range of 150 degrees in the driving rotational direction (B) of the chainring (28a; 28b; 28c).

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