JP2006002921A - Change mechanism for vehicles - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain a light shift operation without increasing machining accuracy even in the case where a relative tilt between a shift pin and a shift groove occurs in a change drum type change mechanism.
A change drum 10 having a shift groove 2 on an outer peripheral surface and a shift fork 12 supported by a shift rod 8 parallel to the change drum 10 are provided. The shift fork 12 engages with the shift groove 2. This is a vehicle change mechanism in which a shift pin 1 is protruded and a shift fork 12 is moved in a shift rod axial direction by a cam action between the shift groove 2 and the shift pin 1. An intermediate portion of the shift pin 1 in the pin axis C5 direction is swollen in the shift groove width direction than both ends in the pin axis C5 direction. Preferably, both end portions in the shift groove width direction of the shift pin 1 are formed in partial spherical shapes located on substantially the same spherical surface.
[Selection] Figure 3

Description

  The present invention relates to a vehicle change mechanism that includes a change drum and a shift fork that engages a shift groove of the change drum, and that shifts by rotation of the change drum.

  FIG. 1 and FIG. 2 show a change drum type change mechanism to which the present invention is applied, except that the shape of the shift pin 1 and the shift groove 2 is the same as the conventional change drum type change mechanism. The general structure of a general change drum type change mechanism will be described with reference to FIGS. 1 and 2.

  In FIG. 1, a transmission shaft 7 provided with a plurality of transmission gears 5 and shift sleeves 6 having different gear stages (gear diameters), a shift rod 8 and a change drum 10 are arranged in parallel in the transmission case. For example, two shift forks 12 are fitted to the shift rod 8 so as to be movable in the direction of the rod axis C2.

  Each shift fork 12 includes a fork portion 12a and the shift pin 1 respectively. The fork portion 12a engages with an annular groove 15 of the shift sleeve 6, and the shift pin 1 is inserted into the shift groove 2 formed on the surface of the change drum. Is engaged.

  FIG. 2 is a simplified perspective view of the change drum 10, and only one shift groove 2 is shown for convenience. The shift groove 2 is formed in an annular shape around the change drum axis C3 and is formed with a curved portion 17 at a predetermined position. The change drum 10 is rotated by a predetermined angle by a change operation using a change pedal (not shown). It has become. In the curved portion 17, a cam action is generated between the shift groove 2 and the shift pin 1, whereby the shift fork 12 moves in the direction of the rod axis C 2, thereby moving the shift sleeve 6 in FIG. 1 in the axial direction. The meshing state of the transmission gear 5 is changed. The other transmission gears that mesh with the transmission gears 5 and 5 are not shown.

  FIG. 9 is an enlarged longitudinal sectional view showing a shift pin 101 conventionally used in the change mechanism as shown in FIGS. 1 and 2. In addition, in order to distinguish from the shift pin 1 of this invention, the code | symbol of the shift pin is set to "101" in FIG.

  In FIG. 9, the shift pin 101 is formed in a cylindrical shape (straight cylinder shape), and its diameter W2 is formed to have a slight clearance with respect to the groove width W1 of the shift groove 2. When the 101 slides relatively in the shift groove 2, one end of the shift pin 101 in the shift groove width direction is in line contact with the side surface 21 (or 22) of the shift groove 2.

In addition, as another structure of the shift pin, there is also a structure in which slidability is improved by providing a rollable steel ball instead of a cylindrical shape (see Patent Document 1).
Japanese Utility Model Publication No.59-139649

  In the change mechanism provided with the cylindrical (straight cylindrical) shift pin 101 as shown in FIG. 9, the shift groove width direction end of the shift pin 101 and the side surface 21 or 22 of the shift groove 2 are brought into line contact as described above. However, when actually manufacturing a product, the perpendicularity error of the shift groove side surfaces 21 and 22 with respect to the change drum shaft core C3 generated during the shift groove processing, the rod shaft generated during the shift pin processing. Cumulative errors of squareness of the pin shaft core C5 with respect to the core C2, accuracy error (gap) when the shift fork 12 is assembled, or inclinations of the shaft cores C2 and C3 when the change drum 10 and the shift rod 8 are assembled By doing so, it is difficult to maintain the parallelism between the side surfaces 21 and 22 of the shift groove 2 and both ends of the shift pin 1 in the shift groove width direction. That is, it is difficult to avoid the state where the shift groove side surfaces 21 and 22 and the axis C5 of the shift pin 101 are relatively tilted, and the following phenomenon occurs.

  (1) In FIG. 9, when the axial center C5 of the shift pin 101 is relatively inclined with respect to the shift groove side surfaces 21 and 22, for example, in the arrow X1 direction, The edge (corner portion) P1 contacts the shift groove side surface 22, or the base portion of the shift pin 101 on the arrow X1 side contacts the opening edge (corner portion) P2 of the shift groove side surface 21. Alternatively, the edges P1 and P2 are in contact with each other at the same time. As described above, when the shift pin 101 and the shift groove side surface 21 (or 22) are in point contact with each other at the end edge P1 of the front end of the shift pin 101 or the end edge P2 of the shift groove side surface 21, the surface pressure is increased and the catch is generated. The mobility is reduced, the drum rotation speed is reduced, and the shift operation becomes heavy.

  (2) Further, in order to suppress wear due to strong rubbing at the end edge (corner portion) P1 of the front end of the shift pin 101 and the end edge (corner portion) P2 of the shift groove side surface 21, surface hardening treatment is performed. This increases the manufacturing cost.

  In addition, in the structure which arrange | positions a steel ball to a shift pin so that rolling is possible like patent document 1, etc., although a light shift operation can be maintained, while a number of parts and an assembly man-hour increase, parts cost also increases.

(Object of invention)
The object of the present invention is to provide a tip of the shift pin even if a relative tilt phenomenon occurs between the side surface of the shift groove and the shift pin due to an error in squareness or assembly accuracy during processing or assembly or a load during operation. Or provide a vehicle change mechanism that eliminates point hitting (deviation) at the edge of the side of the shift groove, maintains a light shift operation, and eliminates the need for special surface treatment on the surface of the shift groove. It is to be.

  In order to solve the above problems, the present invention includes a change drum having a shift groove on the outer peripheral surface, and a shift fork supported by a shift rod parallel to the change drum, and the shift fork engages with the shift groove. In the vehicle change mechanism in which the shift fork is moved in the shift rod axis direction by cam action between the shift groove and the shift pin when the shift pin is rotated by projecting the shift pin, the shift pin is in the middle of the pin axis direction. The part swells in the shift groove width direction from both ends in the pin axis direction.

  In the present invention, preferably, both end portions in the shift groove width direction of the shift pin are formed in a circular arc shape, more preferably in a circular arc shape located on the same circumference.

  In the present invention, preferably, both end portions in the shift groove width direction of the shift pin are formed in a partial spherical shape, and more preferably in a partial spherical shape located on the same spherical surface.

  Further, as another shape of the shift pin, both end portions in the shift groove width direction of the shift pin can be formed in a cross-section “<” shape. In this case, it is preferable that the bent portion of the character “KU” be rounded.

  In addition to the idea of the shape of the shift pin, a portion that is recessed in a substantially arc-shaped cross section can be formed on the side surface of the shift groove.

  (1) Since the intermediate portion of the shift pin in the pin axis direction swells in the shift groove width direction from both ends in the pin axis direction, that is, from the tip portion and the root portion, it is between the side surface of the shift groove and the shift pin. Even if relative tilting occurs, the bulging intermediate portion always comes into contact with the side surface of the shift groove, and the edge (corner portion) of the tip of the shift pin or the opening side of the shift groove as in the prior art. The edge (corner) will not make point contact. Therefore, while maintaining the slidability of the shift pin, it is possible to maintain a light shift operation, and no special surface treatment for wear is required, thereby saving costs. Furthermore, since it is not necessary to improve the shift groove processing of the change drum, the processing of the shift pins, and their assembly accuracy, the management becomes easy and the cost can be reduced.

  (2) If both ends of the shift pin in the width direction of the shift groove are formed in a circular arc shape, the shift pin contacts the side surface of the shift groove even when the side surfaces of the shift pin and the shift groove are relatively tilted. The position hardly changes in the depth direction of the shift groove, and the shift pin can be slid by always maintaining contact at an appropriate position. In particular, the above-described effect is enhanced when the cross-sectional arcs are located on the same circumference.

  (3) If both ends of the shift pin in the shift groove width direction are formed in a partial spherical shape, not only the relative tilting of the shift pin and the side surface of the shift groove in the groove width direction but also the relative direction in the other direction. It can absorb the fall and maintain smooth slidability. In particular, the above effect is enhanced by forming a partial spherical surface located on the same spherical surface.

  (4) In addition to the configuration in which the shape of both ends of the shift pin in the shift groove width direction is variously modified as described above, the shift pin and the shift groove are formed on the side surface of the shift groove so as to be recessed in a substantially arcuate cross section. Even when the side surfaces of the shift groove are relatively tilted, the shift pin can be brought into line contact with the side surfaces of the shift groove, and the slidability is improved.

[First Embodiment]
(Constitution)
1 to 3 show a first embodiment of the present invention, and the entire structure of the change drum type change mechanism shown in FIGS. 1 and 2 is described in the section of the background art. Omitted.

  FIG. 3 is an enlarged vertical cross-sectional view of the shift pin 1 and the shift groove 2 according to the present invention. The shift groove 2 is formed in a U-shaped cross section, and includes a bottom portion 20 parallel to the change drum shaft core C3, and a change drum shaft. It has a pair of side surfaces 21 and 22 perpendicular to the core C3.

The shift pin 1 has a pin shaft core C5 perpendicular to the rod shaft core C2, and projects into the shift groove 2 from the radially outer side of the change drum 10 by a predetermined depth. The shift pin 1 is a rotationally symmetric body having the pin axis C5 as the center of rotation, and the surface shape thereof is formed in a partial spherical shape centered on one spherical center O1 on the pin axis C5. In other words, the intermediate portions 25 and 25 in the pin axis C5 direction (pin length direction) are expanded (swelled) in a cross-section arc shape in the pin radial direction from the tip and root portions in the pin axis C5 direction. It has a barrel shape. The spherical center O1 is set at a position entering the shift groove 2 by a fixed distance d1 from the opening end of the shift groove 2, and the diameter (2R1) of the spherical surface forming the surface of the shift pin 1 is the width of the shift groove. The value is slightly smaller than W1. In addition, a certain distance d2 is secured between the tip of the shift pin 1 and the bottom 20 of the shift groove 2, so that even if the shift pin 1 is largely tilted relative to the side surfaces 21 and 22 of the shift groove 2, The tip of the shift pin 1 does not come into contact with the shift groove bottom surface 20.
(Function)

  When the change drum 10 shown in FIG. 1 is rotated by a predetermined angle by operating a change pedal (not shown) or the like, the shift pin 1 and the shift groove 2 slide relative to each other. When the shift pin 1 comes to the curved portion 17 in FIG. 2, the shift fork 12 moves in the direction of the rod axis C2 due to the cam action of the shift groove 2 and the shift pin 1, whereby the shift sleeve 6 in FIG. 1 moves. Then, the meshing state of the transmission gear 5 is changed.

  In FIG. 3, even if the pin axis C5 of the shift pin 1 is tilted relative to the side surfaces 21 and 22 of the shift groove 2 in the direction of the arrow X1, the surface of the shift pin 1 has a spherical center O1. The contact point of the bulged intermediate portion 25 of the shift pin 1 with respect to the side surface 21 or 22 of the shift groove 2 hardly moves from the contact point P3 when there is no collapse phenomenon, It is always a position that is recessed by a certain distance d1 from the opening end of the shift groove. That is, even when the shift operation is performed in the tilted state as described above, the edge P1 in the groove width direction at the tip of the shift pin 1 or the edge P2 on the opening side of the groove side surface 2 does not become a contact point. Therefore, the shift pin 1 does not get caught on the side surface of the shift groove 2, and the shift operation does not become heavy.

[Second Embodiment]
FIG. 4 shows a second embodiment of the present invention. The shape of the shift pin 1 is exactly the same as the shape of FIG. 3. In addition to this shift pin shape, the side surfaces 21 and 22 of the shift groove 2 Concave portions 21a and 22a that are recessed in a circular arc shape are formed. The recesses 21a and 21b are formed on the groove bottom side with respect to the contact point P3 between the shift pin 1 and the shift groove side surfaces 21 and 22, and have an arc shape having a slightly larger radius than the spherical radius R1 of the surface of the shift pin 1. Yes. The shift groove opening side (radially outward side) from the contact point P3 is formed in a straight cross section perpendicular to the change drum axis C3, whereby the shift pin 1 is inserted into the shift groove 2. It can be done.

  According to the structure of FIG. 4, even if the relative fall between the shift pin 1 and the side surfaces 21 and 22 of the shift groove 2 is large, the arc-shaped surfaces of the recesses 21a and 22a can be kept in a state close to line contact. And slidability is improved.

[Third Embodiment]
FIG. 5 shows a third embodiment of the present invention. This shift pin 1 is a rotationally symmetric body having a pin axis C5 as a rotation center, but the cross section is formed in a substantially "<" shape. Yes. The shape is similar to the so-called abacus ball. However, a small round (round) r1 is formed in the bent portion of the “<”-shaped intermediate portion 25.

  Also in this embodiment, even if relative tilting occurs between the shift pin 1 and the side surfaces 21 and 22 of the shift groove 2, the contact point of the shift pin 1 with respect to the side surfaces 21 and 22 of the shift groove 2 is tilted. When there is no contact point, it hardly moves from the contact point P3, and becomes a position that is recessed by a certain distance d1 from the opening end of the shift groove. At least the edge P1 in the groove width direction at the tip of the shift pin 1 or the edge P2 of the groove side surfaces 21 and 22 does not become a contact point.

[Fourth Embodiment]
FIG. 6 shows a fourth embodiment of the present invention, and this shift pin 1 is also a rotationally symmetric body with the pin axis C5 as the center of rotation, and the surface of the shift pin 1 is formed in a circular arc shape in cross section. The arc-shaped center O2 is deviated from the pin axis C5, and the arc-shaped curvature radius R2 of the outer peripheral surface of the shift pin 1 is larger than the radius R1 in FIG.

  Also in this embodiment, even if relative tilting occurs between the shift pin 1 and the side surfaces 21 and 22 of the shift groove 2, the contact point of the shift pin 1 with respect to the side surfaces 21 and 22 of the shift groove 2 is tilted. When there is no contact point, the position hardly moves from the contact point P3 and becomes a position that is recessed by a certain distance d1 from the opening end of the shift groove. At least the edge P1 in the groove width direction at the tip of the shift pin 1 or the tip P2 of the groove side surfaces 21 and 22 does not become a contact point.

[Fifth Embodiment]
FIG. 7 shows a fifth embodiment of the present invention, and this shift pin 1 is also a rotationally symmetric body with the pin axis C5 as the center, and a bulging intermediate portion formed in the middle of the pin axis C5. 25 is formed in a cross-sectional linear shape parallel to the side surfaces 21 and 22 of the shift groove 2, and is formed in a cross-sectional arc shape from the bulging intermediate portion 25 to the tip end portion and the root end portion in the direction of the pin axis C5. ing.

  In this embodiment, when relative tilting occurs between the shift pin 1 and the side surfaces 21 and 22 of the shift groove 2, the range d3 of the bulged intermediate portion 25 in the direction of the pin axis C5. However, at least the edge P1 in the groove width direction of the tip of the shift pin 1 or the tip P2 of the groove side surfaces 21 and 22 does not become a contact point.

[Other embodiments]
In each of the embodiments shown in FIGS. 3 to 7, the cross-sectional shape of the shift pin 1 is a rotationally symmetric body with the pin axis C5 as the rotation center, but the shift pin 1 according to the present invention is not limited to the rotationally symmetric body. For example, as shown in the horizontal sectional view of the shift pin 1 in FIG. 8, only the both ends of the shift pin 1 in the width direction of the shift groove are bulged intermediate portions 25 in which the intermediate portion in the direction of the pin axis C5 swells. It can also be set as the non-rotation symmetrical body which cut off the both ends of the length direction into the plane 31. In the structure of FIG. 8 as well, the shift operation does not become heavy depending on the relative fall phenomenon between the shift pin 1 and the side surfaces 21 and 22 of the shift groove 2 as in the structure of FIGS. Further, there is no need to perform additional surface treatment.

  The present invention can be applied to a vehicle having a change drum type shift mechanism, such as a motorcycle or a four-wheel vehicle for traveling on rough terrain.

It is a section development view of a change drum type change mechanism to which the present invention is applied. It is a simplified perspective view of the change drum type change mechanism of FIG. It is an expanded vertical sectional view of the shift pin part of the 1st Embodiment of this invention. It is an expansion longitudinal cross-sectional view of the shift pin part of the 2nd Embodiment of this invention. It is an expansion longitudinal cross-sectional view of the shift pin part of the 3rd Embodiment of this invention. It is an expansion longitudinal cross-sectional view of the shift pin part of the 4th Embodiment of this invention. It is an expanded longitudinal cross-sectional view of the shift pin part of the 5th Embodiment of this invention. It is an expanded horizontal sectional view of the shift pin part of other embodiment of this invention. It is an enlarged vertical sectional view of a conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shift pin 2 Shift groove 8 Shift rod 10 Change drum 12 Shift fork 21, 22 Side surface of shift groove 25 Swelling intermediate part

Claims (7)

A change drum having a shift groove on the outer peripheral surface and a shift fork supported by a shift rod parallel to the change drum are provided. A shift pin engaging with the shift groove is projected from the shift fork, and the change drum is rotated. In the vehicle change mechanism that moves the shift fork in the shift rod axis direction by the cam action between the shift groove and the shift pin at the time,
A change mechanism for a vehicle, characterized in that an intermediate portion of the shift pin in the pin axis direction swells in the shift groove width direction from both ends in the pin axis direction.   The vehicle change mechanism according to claim 1, wherein both ends of the shift pin in the width direction of the shift groove are formed to have a substantially arcuate cross section.   The vehicle change mechanism according to claim 2, wherein both ends of the shift pin in the width direction of the shift groove are formed in a circular arc shape that is located on substantially the same circumference.   The vehicle change mechanism according to claim 1, wherein both ends of the shift pin in the shift groove width direction are each formed in a partial spherical shape.   The vehicle change mechanism according to claim 1, wherein both ends of the shift pin in the width direction of the shift groove are formed in a partial spherical shape located on substantially the same spherical surface.   The vehicle change mechanism according to claim 1, wherein both ends of the shift pin in the width direction of the shift groove are formed in a cross-section “<” shape. The vehicle change mechanism according to any one of claims 1 to 6, characterized in that a side portion of the shift groove is formed with a concave portion having a substantially arcuate cross section.

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