Control device for bicycle derailleur

Abstract: A control device for a bicycle derailleur according to the present invention comprises a fixing member, control means for effecting a change speed, a reciprocating member (9) reciprocatively supported by the fixing member and operatively connected to the derailleur to be movable between a forward direction for shifting a chain (3) from a smaller sprocket to a larger sprocket and in a backward direction for shifting the chain from the larger sprocket to the smaller sprocket, said reciprocating member being urged in the backward direction, and a retaining mechanism acting as a one-way mechanism for permitting the reciprocating member to move in the forward direction and preventing the same to move in the backward direction thereby to positioning and main­ taining the reciprocating member. The retaining mechanism (H) can retain the recipro­ cating member in one set position or an intermediate position displaced from the set position for each of a plurality of speeds in the forward direction, while can release the positional maintenance of the recipro­ cating member thereby to selectively maintain the reciprocating member in a set position displaced from the maintaining position, or in a further set position more displaced in the backward direction.

Description: BACKGROUND OF INVENTION Field of the Invention The present invention relates to a control device for a bicycle derailleur according to the first part of the main claim. One example of a known retaining mechanisms for derailleur control devices of this type is shown in GB 2,169,065A disclosing the reciprocating member pivotally supported by the fixing member, recesses defined in a lower face of the reciprocating member for stepwise positionally maintaining the reciprocating member, and further recesses defined in an upper face of the reciprocating member for stepwise releasing the reciprocating member. A ratchet mechanism is structured to include a retaining pawl directing upwardly and defined in a button constantly urged upwardly for engaging the lower recesses, and a restraining pawl directing downwardly and defined in the button for engaging the upper recesses and effecting a stepwise release when pushing down the button. The reciprocating member is maintained in one set position for each of a plurality of speeds in the forward and backward directions by alternately engaging two pairs of pawls and recesses. In effecting the change speed to shift the same speed condition both in the forward direction and the backward direction by shifting the chain through the derailleur, it is required, when shifting the chain from the smaller sprocket to the larger sprocket, to overshift a chain portion supported by the derailleur to the larger sprocket beyond a position corresponding to a sprocket to be engaged (Fig. 12(a)) . On the contrary, it is required, when shifting the chain from the larger sprocket to the smaller sprocket, to overshift the chain portion supported by the derailleur to the smaller sprocket beyond the position corresponding to the sprocket to be engaged (Fig. 12(b)). It should be noted that the overshift amount is substantially constant when the chain is shifted from the larger sprocket to the smaller sprocket while the overshift amount varies when the chain is shifted from the smaller sprocket to the larger sprocket. This is because a tension is intensely changed when shifting from the smaller sprocket to the larger sprocket. The more increased the tension is, the more increased the overshift amount is. However, according to the conventional structure, the reciprocating member is maintained in only one set position for each speed and not in an overshift position when the chain is shifted from the smaller sprocket to the larger sprocket, which does not allow a smooth change speed. In addition, when the reciprocating member is returned to the backward direction, the pawl is engaged with one of the recesses for the stepwise release thereby to prevent a plurality of speed changes and a quick speed change control. A control device according to the preamble of claim 1 is known from GB-A 20 12 893. Another bicycle speed change lever with the possibility of overshifting is known as well (US-A 4267 744). Finally, another control known from EP-A 03 92 457, this document falling under Article 54 (3) EPC, however SUMMARY OF THE INVENTION An object of the present invention is to provide a control device for a bicycle derailleur which can realize an easy, quick and effective change speed by shifting a chain. The above-noted object, is achieved by a retaining mechanism according the features of the second part of the main claim. With such structure, when shifting the chain from the larger sprocket to the smaller sprocket to effect the change speed, the overshift amount is constant as set forth above and the reciprocating member is maintained in one set position for each speed, and thus the reciprocating member is only required to be maintained in one set position for each of the plurality of speeds in the backward direction. On the contrary, when the chain is shifted from the smaller sprocket to the larger sprocket, the overshift amount varies with each speed position as noted above, and thus the reciprocating member is maintained in the appropriate intermediate position for each of the plurality of speeds in the forward direction to reliably shift the chain. It should be further noted that when the reciprocating member is moved in the backward direction, a quick and easy change speed is desirably and smoothly effected by a simple operation of just moving the reciprocating member to one set position determined as a suitable chain shift position for each speed condition. Furthermore, the retaining mechanism is selectively operable to maintain the reciprocating member in a set position displaced from the maintaining position, or a further set position displaced from the set position in the backward direction. As a result, one can be free from a troublesome of many time operations when shifting the chain from the larger sprocket to the smaller sprocket. The retaining mechanism according to the invention comprises a ratchet mechanism including a pawl and a plurality of teeth to be engaged with each other in which the teeth have projections defined to become radially shorter at respective engaging positions with the pawl as the reciprocating member moves in the forward direction thereby to change a relative position between the pawl and the teeth in a radial direction by the control means. In this structure, the reciprocating member can be maintained in a position for each speed in the backward direction by controlling a retracting amount of the ratchet pawl utilizing the length variance of teeth projections. In other words, the reciprocating member can be maintained in one set position for each speed in the backward direction, utilizing the points defining various lengths of the projections of the ratchet teeth. This allows the change speed effected by moving the reciprocating member in the backward direction to be realized by a simple operation of changing the relative radial position between the pawl and the teeth. In working the present invention, the retaining mechanism may be selectively operable to maintain the reciprocating member in any one of the set positions in response to an operational amount of the control means when moving the reciprocating member in the backward direction. According to such construction, since it is easy to adjust the operational amount of the control means, the change speed is effected more quickly with more comfortable feels by a fine adjustment of the control means. Other objects and effects will be apparent from the following description of embodiments. BRIEF DESCRIPTION OF THE DRAWINGS The drawings show a control device for a bicycle derailleur embodying the present invention, in which Figs. 1 to 6 are top plan views showing various change speed control conditions achieved by the control device of the present invention, Fig. 7 is a disassembled perspective view of the control device, Fig. 8 is a developed vertical sectional view of the control device, Fig 9 is a horizontal sectional plan view of a mounting structure of a wire to a rotatable member, Fig. 10 is a top plan view showing a shape of a cam portion, Fig. 11 is a side view of a change speed device of a bicycle, Figs. 12(a) and 12(b) is illustrative views showing shifting conditions of a chain, and Figs. 13 and 14 are top plan views of other embodiments according to the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments according to the present invention will be described hereinafter, referring to the accompanying drawings. As shown in Fig. 11, a change speed device for a bicycle comprises three front sprockets 1a, 1b and 1c having different diameters to one another, a plurality of rear sprockets 2 having different diameters to each other, a chain 3 engaging and extending between the front sprockets 1a, 1b and 1c and the rear sprockets 2, a front derailleur 4, and a rear derailleur 5. The front sprockets 1a, 1b and 1c are rotated by a pedal 6, and the rear sprockets 2 are rotated with a rear wheel in unison. Referring to Figs. 12(a) and 12(b), the front derailleur 4 mainly includes a chain control portion 4A and a link mechanism 4B supporting the chain control portion 4A to be movable in a juxtaposing direction of the sprockets. A spring which is not illustrated is incorporated into the link mechanism 4B for urging the chain control portion 4A to the small sprocket 1a. A control device for the front derailleur 4 is attached to a handle 7, which will be described in detail below. As shown in Figs. 1 to 9, the control device comprises a rotatable member 9 as a reciprocating member operatively connected to the front derailleur 4 through a release wire 8, a retaining mechanism H for positioning and maintaining the rotatable member 9 in a forward direction F of the rotatable member 9 for shifting the chain 3 from the smaller sprocket to the larger sprocket and in a backward direction R of the rotatable member 9 for shifting the chain 3 from the larger sprocket to the smaller sprocket, respectively, a forward movement control lever 10 for the rotatable member 9, and a backward movement control lever 11 for the rotatable member 9. As shown in Figs. 8 and 11, the control device is assembled to a support frame A of a brake control lever B fixed to the handle 7 in which the forward movement control lever 10 and the backward movement control lever 11 are positioned to be easily pushed in the forward direction F of the rotatable member 9 by the thumb of the cyclist holding a handle grip 7A. The retaining mechanism H can maintain the rotatable member 9 in one set position for each of a plurality of speeds in the backward direction R, and in an intermediate position displaced from the set position for each of the plurality of speeds in the forward direction F. More particularly, the retaining mechanism H utilizes a ratchet mechanism permitting the rotatable member 9 to move in the forward direction F while preventing the rotatable member 9 to move in the backward direction R. The ratchet mechanism includes ratchet teeth 12 moving with the rotatable member 9 and arranged with teeth projections being defined to become radially longer stepwise in the forward direction F, and a ratchet pawl 13 operable for varying a retracting amount thereof, thereby to maintain the rotatable member in the positions corresponding to the plurality of speeds in the backward direction R. The rotatable member 9 is urged to return by a torsion coil spring 14 acting upon an urging force of the front derailleur 4 toward the smaller sprocket and upon the rotatable member 9. Next, the retaining mechanism H and the control mechanism of the forward movement control lever 10 and the backward movement control lever 11 will be described. The reference symbols F and R for the both directions will be omitted hereinafter. As shown in Figs. 7 to 9, a wire support 15 with an outer wire end supporting portion 15a for the release wire 8 is attached to the brake control lever support frame A. The wire support 15 carries a restraining member 16 placed thereon for restraining the return limit of the rotatable member 9. The restraining member 16 has a receiving portion 16a for engaging a received portion 9a defined in the rotatable member 9. A support shaft 17 extends through the brake control lever support frame A, the wire support 15 and the return limit restraining member 16 to be relatively unrotatable. The support shaft 17 is fixed to the brake control lever support frame A through a bolt 18. The rotatable member 9 is rotatably fitted on the support shaft 17 to be placed on the return limit restraining member 16. The rotatable member 9 has an inner wire end supporting portion 9b for the release wire 8, an inner wire end guide groove 9c and an inner wire take-up sleeve 9d. The rotatable member 9 accommodates the torsion coil spring 14 engaging at one end thereof with a recess 17a of the support shaft 17 and inserted at the other end thereof into the rotatable member 9. A ratchet teeth defining member 12A is fitted on the rotatable member 9. The ratchet teeth defining member 12A includes a received portion 12a contacting a receiving portion 9e of the rotatable member 9 to be rotatable in unison. The backward movement control lever 11 is rotatably fitted on the support shaft 17 to be placed on the ratchet teeth defining member 12A. The backward movement control lever 11 includes a boss portion defining a cam portion 11A for retracting the ratchet pawl 13. The backward movement control lever 11 is urged to the backward direction through a torsion coil spring 18. The return limit of the lever 11 is restrained by an oscillating limit restraining member 19, and the pushing limit of the lever 11 toward the forward direction is restrained by a contact between the lever and the ratchet pawl 13. The restraining member 19 is unrotatably fitted on the support shaft 17 and defines in its outer periphery a receiving portion 19a corresponding to a received portion 11a of the backward movement control lever 11 for restraining the return limit of the lever. The backward movement control lever 11 further defines a received portion 11b contacting a boss portion of the ratchet pawl 13. The ratchet pawl 13 is rotatably fitted on a pivot shaft 20 screwed at one end to the brake control lever frame A, and is urged toward an engaging direction through a torsion coil spring 21a supported in turn at one end by a supporting portion 19b defined in the restraining member 19. The pivot shaft 20 is fixed at the other end to the restraining member 19 by a screw 22 thereby to constitute the retaining mechanism H acting as a one-way mechanism for positioning and maintaining the reciprocating member 9 by permitting the forward movement thereof and preventing the backward movement thereof through the pawl 13 and the teeth 12. The forward movement control lever 10 is relatively rotatably fitted on the support shaft 17 to be placed on the restraining member 19. The forward movement control lever 10 includes a support pin 10a fitting to a ratchet pawl 23 for controlling the forward movement of the rotatable member. The ratchet pawl 23 is urged toward an engaging direction through a torsion coil spring 21b, and contacts a contact portion 12b of the ratchet teeth defining member 12A or engages one of the ratchet teeth 12 thereby to rotate the rotatable member 9 in accordance with an oscillation of the forward movement control lever 10. The forward movement control lever 10 is oscillatable within a predetermined range restricted by contact between a pair of receiving portions 19c of the restraining member 19 and the ratchet pawl 23, and is urged to return toward the backward direction by a torsion coil spring 24, thereby to constitute the one-way mechanism for moving the rotatable member 9 in the forward direction whenever the forward movement control lever 10 is oscillated in the forward direction. When moving the rotatable member 9 in the backward direction, it is required to disengage the ratchet pawl 23 of the forward movement control lever 10 from one of the ratchet teeth 12 as well as to disengage the ratchet pawl 13 from one of the ratchet teeth 12 by retracting the ratchet pawl 13 by using the cam portion 11A. Thus, the backward movement control lever 11 similarly defines a cam portion 11B in order to retract the ratchet pawl 23 for the forward movement control. Numeral 25 denotes a flange bolt screwed to the support shaft 17 for supporting the forward movement control lever 10. Numeral 26 indicates ring spacers disposed in appropriate portions, respectively. According to the present invention, three different speeds can be obtained by shifting the chain 3 between the three front sprockets 1a, 1b and 1c, in which a condition with the chain 3 engaging the small sprocket 1a will be referred as a low speed condition, a condition with the chain 3 engaging the intermediate sprocket 1b as a mid speed condition, and a condition with the chain 3 engaging the large sprocket 1c as a top speed condition. Referring now to Fig. 12(a), when moving the rotatable member 9 in the forward direction to effect the change speed in the order of the low, the mid and the top speed conditions by shifting the chain from the smaller sprocket to the larger sprocket, it is required to overshift a chain portion supported by the chain control portion 4A of the front derailleur 4 to the larger sprocket beyond a position corresponding to the sprocket to be engaged. The more increased a tension of the chain 3 is, the more increased an over-shift amount L1 is. In contrast, as shown in Fig. 12(b), when moving the rotatable member 9 in the backward direction to effect the change speed in the order of the top, the mid and the low speed conditions by shifting the chain from the larger sprocket to the smaller sprocket, it is required to overshift the chain portion supported by the chain control portion 4A of the front derailleur to the smaller sprocket beyond a position corresponding to the sprocket to be engaged. In this case, an overshift amount L2 is constant. This allows, when moved in the forward direction to effect the change speed, the rotatable member 9 to be maintained in a plurality of stepwise positions in the mid and the top speeds, respectively, by varying an engaging position of the ratchet pawl 13 with the ratchet teeth 12. On the contrary, when moved in the backward direction to change the top speed to the mid speed, the rotatable member 9 is maintained in one single set position corresponding to the mid speed by defining the ratchet teeth projections to become radially longer stepwise in the forward direction, and by varying the retracting amount of the ratchet pawl 13 with the pushing amount by the backward movement control lever 11 in the forward direction, as set forth above. Further, when moved in the backward direction to change the mid speed to the low speed, the rotatable member 9 is maintained in one set position corresponding to the low speed by engaging the received portion 9a of the rotatable member 9 with the receiving portion 16a of the return limit restraining member 16, and by varying the retracting amount of the ratchet pawl 13 with the pushing amount by the backward movement control lever 11 in the forward direction. The shapes of the ratchet teeth 12 and the cam portion 11A of the backward movement control lever 11 will be described in more detail referring to Fig. 10. The ratchet teeth 12 is essentially divided into a section Sa having the longer teeth projections with an increased diameter Ra, and a section Sb having the shorter teeth projections with a reduced diameter Rb. Two of the teeth in the section Sb positioned at an end portion in the backward direction have further shorter projections with further reduced diameters Rc and Rd, respectively. With this structure, when rotated in the forward direction to shift to the top speed, the rotatable member 9 can be slightly returned to the backward direction if the chain 3 contacts the chain control portion 4A of the front derailleur 4 to produce a noise. This returning operation is effected by pressing the rotatable member so as to retract the ratchet pawl 13 at the cam portion 11A by a small amount. There is also a possibility of producing such contacting noise between the chain 3 and the chain control portion 4A of the front derailleur 4 when rotating the rotatable member 9 in the forward direction to shift to the mid speed. In this case also, the rotatable member can be pressed so as to retract the ratchet pawl 13 at the cam portion 11A by a small amount thereby to slightly return to the backward direction. The cam portion 11A is essentially includes an inclined cam face K1 for retracting the ratchet pawl 13 by a small amount when shifted to the top speed condition, a cam face K2 for retracting the ratchet pawl 13 by a predetermined amount when shifted from the top speed condition to the mid speed condition, and a cam face K3 for retracting the ratchet pawl 13 by a predetermined amount when shifted from the mid speed condition to the low speed condition. A series of operations of the front derailleur 4 will be described below. Figs. 1 to 4 illustrate an operation for shifting from the low speed condition to the top speed condition. When shifting from the low speed condition to the mid speed condition, the forward movement control lever 10 is operated in the forward direction where the ratchet pawl 23 for the forward movement presses the contact portion 12b of the ratchet teeth defining member 12A thereby to move the rotatable member 9 in the forward direction. When shifting from the mid speed condition to the top speed condition, the forward movement control lever 10 is operated in the forward direction thereby to move the rotatable member 9 in the forward direction through the ratchet pawl 23 for the forward movement engaging the ratchet teeth 12. Figs. 5 and 6 illustrate an operation for shifting from the top speed condition to the low speed condition. The mid speed is obtained by operating the backward movement control lever 11 by one step in the forward direction, and the low speed is obtained by operating the backward movement control lever 11 by two steps in the forward direction. That is, it is possible to shift from the top speed condition to the low speed condition in a single operation by operating the backward movement control lever 11 by a great amount. As seen from Fig. 8, the take-up sleeve 9d of the rotatable member 9 has a larger diameter at a portion between positions corresponding to the low speed condition and the mid speed condition, and a smaller diameter at a portion between positions corresponding to the mid speed condition and the top speed condition thereby to allow a great force to be produced by a less operational force when shifting from the mid speed condition to the top speed condition. This contributes to a light operation even if a change speed resistance is intense when shifting from the mid speed condition to the top speed condition. One of the causes of a great change speed resistance produced when shifting from the mid speed condition to the top speed condition is that the chain 3 is pressed against one of lateral sides of the large sprocket 1c corresponding to the top speed condition by one of a pair of chain pressing pieces 4a of the chain control portion 4A for shifting the chain 3 to the larger sprocket. Other embodiments according to the present invention will be described hereinafter. The derailleur control device according to the present invention will perform a remarkable effect when applied to an operation of the front derailleur in which the maintaining position of the reciprocating member 9 tends to be vary for the same speed conditions in the forward direction and the backward direction, but may be applied to an operation of the rear derailleur 5. Of course, it may also be used in various types of derailleur. In the foregoing embodiment, the reciprocating member 9 can be maintained in the plurality of stepwise positions in the forward direction by utilizing the ratchet mechanism, but can be maintained in stepless positions in the forward direction by utilizing a friction mechanism for providing a resistance when the reciprocating member 9 moves. In order to maintain the reciprocating member 9 in one set position for each speed in this case, an element moving with the reciprocating member 9 may be provided with received portions having projections varying stepwise along the forward direction in which a retracting amount of an element cantactable with the received portions can be controlled by the backward movement control lever 11, in the same manner as in the ratchet pawl 13 noted above. In this embodiment, a friction effect caused by the friction mechanism can be released by the backward movement control lever 11. With respect to the reciprocating member 9 maintained in the plurality of stepwise positions in the forward direction by using the ratchet mechanism, the following modification is possible: The ratchet pawl 13 may be supported by the reciprocating member 9 to be moved in unison while the ratchet teeth 12 can be supported by a fixed member, or the backward movement limit of the reciprocating member 9 can be also restricted by the heights of the teeth projections. Two levers, i.e. the forward movement control lever 10 and the backward movement control lever 11, can be replaced by a single lever. More particularly, the forward movement control lever 10 in the first embodiment may be structured to include a distal end bendable with respect to a proximal end thereof in another direction to the operating direction of the reciprocating member 9 thereby to move the cam portions 11A and 11B, or may be structured as shown in Figs. 13 and 14. In those figures, a stopper 27 for restraining the return limit of the forward movement control lever 10 is resiliently supported by a compression coil spring 28 thereby to allow the forward movement control lever 10 to be operated against a resilient force of the coil spring 28 beyond the operational rotation limit of the reciprocating member 9. A rotatable element 29 may be provided defining a cam portion 29A for retracting the ratchet pawl 13, and an arcuate slot 30 for receiving an engaging pin 31 attached to the forward movement control lever 10 to be rotated in unison. A further cam portion 32 may be fixedly provided for disengaging the ratchet pawl 23 for the forward movement of the reciprocating member 9 from the ratchet teeth 12 when operating the forward movement control lever 10 against the resilient force of the coil spring 28 beyond the rotation limit of the reciprocating member 9. With this construction, when operating the forward movement control lever 10 within the operational rotation limit of the reciprocating member 9, the forward movement control lever 10 can be operated against the resilient force of the coil spring 28 beyond the rotation limit of the reciprocating member 9 thereby to vary the retracting amount of the ratchet pawl 13 to operate the reciprocating member 9 in the backward direction as well as in the forward direction as set forth in the first embodiment. The reciprocating member 9 may be slidable instead of being rotatable. The linkage between the reciprocating member 9 and the derailleur can be variantly changed. Whether the reciprocating member 9 is moved from the top speed corresponding position to the low speed corresponding position by a single operation may be selected not only by the backward movement control lever 11, but also by the respective cam faces of the cam portion 11A to be switchable and displaced along a rotational axis thereof.

Claims: A control device for a bicycle derailleur comprising; a fixing member (A), control means (10, 11) for effecting a change of speed, a reciprocating member (9) reciprocatively supported by the fixing member (A) and operatively connected to the derailleur to be movable between a forward direction (F) for shifting a chain (3) from a smaller sprocket to a larger sprocket and in a backward direction (R) for shifting the chain (3) from the larger sprocket to the smaller sprocket, said reciprocating member being urged in the backward direction (R), and a retaining mechanism (H) acting as a one-way mechanism for permitting the reciprocating member (9) to move in the forward direction (F) and preventing the same to move in the backward direction (R) thereby positioning and maintaining the reciprocating member (9), characterized in that the retaining mechanism (H) can retain the reciprocating member (9) in one set position which corresponds to a certain speed or an intermediate position which corresponds to an amount of overshift for a given speed. displaced from the set position for each of a plurality of speeds in the forward direction (F), while the reciprocating member can be released from a maintained position to thereby selectively maintain the reciprocating member (9) in a set position displaced from said maintained position in the backward direction, or in a further set position more displaced in the backward direction (R); and in that the retaining mechanism (H) comprises a ratchet mechanism including a pawl (13) and a plurality of teeth (Sb) engaged with each other, the teeth (Sb) having teeth projections defined to become radially shorter at the engaging positions with the pawl (13) as the reciprocating member 9 moves toward the forward direction (F). A control device as claimed in claim 1 characterized in that the retaining mechanism (H) is adapted to selectively maintain the reciprocating member 9 in any one of the set positions in response to an operational amount of the control means (10) when the reciprocating member 9 is moved in the backward direction. A control device as claimed in claim 2 characterized in that the pawl (13) and the teeth (Sb) being positionally adjustable relative to each other in a radial direction by the control means (10). A control device as claimed in claim 3 characterized in that the retaining mechanism (H) includes cam means (11A) having various lengths of projections for moving the pawl (13) and acting as a releasing means. A control device as claimed in claim 4 characterized in that the cam means (11A) contacts a distal end of the pawl (13). A control device as claimed in claim 5 characterized in that the control means includes a forward movement control lever (10) for moving the reciprocating member in the forward direction (F), the control device further comprising a one-way mechanism between the forward movement control lever (10) and the reciprocating member (9) including a pawl (23) and a plurality of teeth (Sa) engaged with each other and urged to an initial position when the control lever (10) is operated, the pawl (23) for controlling the forward movement being disengageable from the plurality of teeth (Sa) by cam means (11B) when released from the positional maintenance by the retaining mechanism. A control device as claimed in claim 6 characterized in that the reciprocating member (9) is pivotally supported by the fixing member (A), and the teeth (Sa, Sb) are rotatable with the reciprocating member 9. A control device as claimed in claim 7 characterized in that the control means further includes a backward movement control lever (11) pivotally supported by the fixing member (A), and the respective cam means (11A, 11B) are rotatable with the backward movement control lever (11). A control device as claimed in claim 8 characterized in that the teeth (Sa, Sb) are radially projected from an axis pivotally supporting the reciprocating member 9. A control device as claimed in claim 9 further comprising a wire acting as means for operatively interconnecting the derailleur and the control device, the wire being unwound from the control device in the backward direction (R).

Inventors: NAGANO MASASHI, NAGANO, MASASHI
Applicants: SHIMANO KK, SHIMANO INC.
Application year: 1990
Main classification: B62M25
IPC codes: B62M25