JP6551125B2 - Gear transmission - Google Patents

Description

  The present invention relates to a gear transmission provided with an idler gear mounted on a rotary shaft so as to be relatively rotatable via a cylindrical slide bearing.

  In a manual transmission for a vehicle in which a normally meshed gear is incorporated, a normally meshed gear other than the normally meshed gear for achieving the selected gear position is a needle roller bearing or the like with respect to a rotation shaft such as a transmission output shaft. It is relatively rotatably supported via a bearing member. Such a gear transmission is well known in Patent Document 1 and the like.

Utility model registration 2548901 gazette

  In order to reduce the parts cost and manufacturing cost of a manual transmission for a vehicle incorporating the always meshed gear described above, it may be considered to incorporate a slide bearing between the rotary shaft and the meshed gear at all times instead of the needle roller bearing. ing.

  On the other hand, as a gear incorporated in a vehicle manual transmission, a helical gear having a large torque transmission force and a low noise is generally used. However, since the helical gear simultaneously generates a thrust force during its rotation as well known, the helical gear itself is axially urged along with its rotation. More specifically, if this is a constant meshing gear, its rotational axis tends to be inclined with respect to the rotational axis of the rotational shaft that supports it. For this reason, when the slide bearing is incorporated between the rotating shaft and the normally meshed gear instead of the needle roller bearing described above, the contact pressure between the end of the slide bearing on which the meshed gear always inclines and the normally meshed gear May become seized due to running out of oil.

  In order to avoid such problems, it is possible to suppress an increase in surface pressure with the sliding bearing when the meshing gear is always inclined by processing the outer peripheral surface of the sliding bearing into a barrel shape having a middle convexity. . However, when processing the outer peripheral surface of the slide bearing into a barrel shape, high processing accuracy is required, so the manufacturing cost is high, and there is a large difference in cost in comparison with the case where needle roller bearings are used. It will be gone.

  An object of the present invention is to provide an idle gear mounted rotatably on a rotary shaft via a cylindrical slide bearing, and to obtain the same durability without using expensive needle roller bearings To provide a gear transmission.

  A gear transmission according to the present invention comprises a rotary shaft, a cylindrical slide bearing fitted to the rotary shaft, an idle gear rotatably fitted to the rotary shaft through the slide bearing, and the rotary gear. It has a stopper provided on a shaft and having an abutment surface abutting on one end surface of the slide bearing, and a press-fit member press-fit fitted on the rotation shaft and having an abutment surface abutting on the other end surface of the slide bearing In the gear transmission, at least one of the end face and the other end face of the slide bearing includes a frustoconical surface continuing to the outer peripheral side, and the contact surface of the stopper and the contact surface of the press-fit member The contact surface in contact with at least one of the end surface and the other surface of the slide bearing of the above is a frusto-conical surface complementary to the frusto-conical surface of the slide bearing. It is said that.

  In the present invention, when the press-fit member is pressed into the rotary shaft so that the slide bearing is compressed between the press-fit member and the stopper, the contact between the frustoconical surface of the abutment surface and the frustoconical surface of the slide bearing As a result of the component force, the slide bearing is bent in the shape of a mid-convex barrel. Therefore, the gap between the outer peripheral surface of the slide bearing and the inner peripheral surface of the floating gear is larger at both ends of the slide bearing than in the middle portion thereof.

  According to the gear transmission of the present invention, the slide bearing can be maintained in a state in which it is elastically deformed in the shape of a barrel with a convex convex shape, so the gap between both ends of the slide bearing and the idle gear can be a longitudinal intermediate portion of the slide bearing. It can be made larger than the clearance between the wheel and the idle gear. For this reason, even if the rotation axis of the floating gear is inclined during rotation, it is possible to suppress an increase in the contact pressure between the end of the slide bearing and the floating gear, and troubles such as seizure can be avoided. . In addition, since the slide bearing can be elastically deformed into a barrel shape easily and reliably, it is not necessary to manufacture such a mid-convex barrel slide bearing by machining. As a result, in a gear transmission having an idle gear mounted so as to be relatively rotatable with respect to the rotation shaft, it becomes possible to adopt a low cost cylindrical slide bearing in place of the expensive needle roller bearing. It is possible to obtain a gear transmission of good quality at low cost.

1 is a cross-sectional view showing a schematic structure of an embodiment of a gear transmission according to the present invention. FIG. 2 is a cross-sectional view extracting and enlarging the contact portion between the pressure gear and the second bearing bush in FIG. 1, and the lower half of the figure shows a state before the pressure gear presses against the second bearing bush. It is a graph showing the relationship between the cone angle and the amount of deflection of the bearing bush when the press-fit load is constant.

  An embodiment in which a gear transmission according to the present invention is applied to a manual transmission will be described in detail with reference to FIGS. However, the present invention is not limited to such an embodiment, and can be applied to any gear transmission having an idle gear that is relatively rotatably fitted to the rotation shaft via a slide bearing.

  The cross-sectional structure in which a part of the manual transmission according to the present invention is extracted and enlarged is schematically shown in FIG. 1, and the part is extracted and enlarged and illustrated in FIG. 2, but the elastic deformation of the bearing bush is drawn exaggeratedly ing. The transmission output shaft (hereinafter simply referred to as output shaft) 10 as a rotary shaft in the present invention in which oil passage 10a is formed inside is a hollow stepped shaft having a step 11, but is not limited thereto. I will not. A washer 20, a first bearing bush 30, a hub 40 and a second bearing bush 50 are attached to an intermediate portion of the output shaft 10 in order from the side closer to the step 11. A spline 12 is formed at the end of the intermediate portion of the output shaft 10, and a press-fit gear 60 is spline-fitted thereto with a predetermined press-fit load, and the press-fit gear 60 is integrally fixed to the output shaft 10 It has become.

  Accordingly, the annular washer 20 is sandwiched between the step 11 of the output shaft 10 and the cylindrical first bearing bush 30 rotatably supporting the first always meshing gear 70. It has become. The annular hub 40 as a stopper in the present invention together with the washer 20 is between the first bearing bush 30 and the cylindrical second bearing bush 50 rotatably supporting the second normally meshed gear 80. It is in the state of being caught between. The first bearing bush 30 and the second bearing bush 50 as a slide bearing in the present invention are in a state of being sandwiched between the hub 40 and the press-fit gear 60 as a press-fit member in the present invention.

  The press-in gear 60 and the normally meshed gears 70, 80 respectively mesh with corresponding synchronous gears 61, 71, 81 attached to a driven shaft (not shown). A well-known synchromesh mechanism or the like (not shown) is disposed between two normally meshed gears 70, 80 adjacent to each other with the hub 40 interposed therebetween, whereby either one of the meshed gears 70, 80 is always integral with the output shaft 10 And the desired gear is achieved.

  The press-fit load of the press-fit gear 60 against the output shaft 10 is a convex shape in which the first and second bearing bushes 30, 50 are compressed along the axial direction (left and right in FIG. 1) and have a desired deflection amount δ. It is set to be elastically deformed into a barrel shape. For this reason, the first and second bearing bushings 30 and 50 are mounted on the output shaft 10 in an intermediate fit or interference fit, but not limited thereto. On the outer peripheral surface of these bearing bushings 30 and 50, a plurality of oil grooves 31 and 51 extending parallel to each other from one end surface to the other end surface respectively extend in the circumferential direction of these bearing bushings 30 and 50 It is formed at regular intervals. The oil passage 10a of the output shaft 10 and the oil grooves 31 and 51 of the bearing bushings 30 and 50 are connected via communication passages 10b and 30a and 50a formed in the output shaft 10 and the bearing bushings 30 and 50, respectively. There is. As a result, the pressure oil flowing through the oil passage 10a is led to the oil grooves 31, 51 through the communication passages 10b, 30a, 50a, and simultaneously meshed gears 70, 80, bearing bushes 30, 50, press-in gear 60, hub 40 , Lubrication between the washers 20 is smoothly performed. As a result, the simultaneous meshing gears 70 and 80 can be prevented from being seized or the like between the bearing bushings 30 and 50, the hub 40, the press-in gear 60 and the washer 20.

  The meshing gears 70, 80 are in contact with the bearing bushes 30, 50 between the inner peripheral surfaces of the central holes 70a, 80a formed in the meshing gears 70, 80 and the outer peripheral surface of the bearing bushes 30, 50, respectively. An appropriate annular gap is formed to be rotatable.

  One end face of the bearing bushes 30 and 50 facing the press-fit gear 60 in the present embodiment includes frustoconical surfaces 32 and 52 continuing to the outer peripheral side. The apex angle α of the truncated conical surfaces 32 and 52 is preferably about 140 to 160 degrees, but is not limited thereto. The press-in gear 60 and the abutment surfaces 62, 42 of the hub 40 abutting on one end face of the bearing bushings 30, 50 are complementary to the truncated conical surfaces 32, 52 formed in the bearing bushings 30, 50. Although it is a frusto-conical surface, it need not be exactly the same as the apex angle α of the frusto-conical surfaces 32, 52 of the bearing bushings 30, 50. In short, by pressing the press-in gear 60 into the spline 12 of the output shaft 10 with a predetermined press-in load, the frusto-conical surface 61 of the press-in gear 60 presses against the frusto-conical surface 52 of the bearing bush 50, and the bearing bush 30 , 50 need only be elastically deformed from the state shown in the lower half of FIG. 2 to the middle convex barrel shape shown in the upper half.

  Here, the relationship between the apex angle of the truncated conical surfaces 32 and 52 and the amount of deflection of the bearing bushes 30 and 50 when the press-fit load of the press-fit gear 60 with respect to the output shaft 10 is set constant is shown in FIG. It will be appreciated that there is a correlation between the apex angle of the frusto-conical surfaces 32, 52 and the amount of deflection of the bearing bushings 30, 50, as is apparent from FIG. Therefore, by appropriately setting the press-in load and the apex angles of the truncated conical surfaces 32, 52, the radial deflection amount δ of the bearing bush 30, 50 can be defined to a desired value.

  As described above, by elastically deforming the bearing bushes 30, 50 in the form of a barrel having a convex convex shape, both end portions in the longitudinal direction (left and right direction in FIG. 1) of the bearing bushes 30, 50 and the meshing gears 70, 80 are constantly engaged. It is possible to form a gap that spreads like a bowl between them. As described above, the constant meshing gears 70 and 80 formed of helical gears together with the synchronous gears 71 and 81 are in a state of being constantly meshed with the synchronous gears 71 and 81. Therefore, the normally meshing gears 70, 80 receive thrust force simultaneously with the rotational force from the synchronous gears 71, 81 and are displaced in the axial direction of the output shaft 10, and at the same time the rotation axis of the meshing gears 70, 80 is the output shaft 10 The end of the central holes 70a and 80a of the meshing gears 70 and 80 is always closer to the outer peripheral surface of the bearing bushes 30 and 50 while being inclined with respect to the rotation axis. However, since the bearing bushes 30, 50 are in the shape of a barrel having a convex shape, it is possible to avoid an increase in surface pressure between the end of the bearing bushes 30, 50 and the meshing gears 70, 80 at all times. It is possible to prevent the occurrence of burn-in between components.

  In the embodiment described above, the frustoconical surfaces 32, 52 are formed only on one end face side of the bearing bushings 30, 50, but these frustoconical surfaces 32, 52 are also formed on the other end surfaces of the bearing bushes 30, 50. It is possible. In this case, needless to say, it is necessary to form complementary frustoconical surfaces also on the portions of the hub 40 and the washer 20 that abut on the other end faces of the bearing bushes 30 and 50. Alternatively, the frusto-conical surface may be formed only on the other end side of the bearing bushes 30 and 50. In any case, by mounting the press-fit gear 60 on the output shaft 10 with a predetermined press-fit load, the bearing bushes 30, 50 can be elastically deformed into a barrel-like convex shape.

  The present invention should be construed only from the matters described in the claims, and in the embodiment described above, in addition to the matters described in all the changes and modifications included in the concept of the invention. It is possible. That is, all the matters in the above-mentioned embodiment are not for limiting the present invention, and may be arbitrarily changed according to the use, purpose, etc. including the composition which is not directly related to the present invention. It is a thing.

DESCRIPTION OF SYMBOLS 10 Transmission output shaft 40 Hub 42 Abutting surface 50 2nd bearing bush 52 Cone conical surface 60 Press-fit gear 62 Abutting surface 80 2nd constant meshing gear

Claims (1)

A rotation axis;
A cylindrical slide bearing fitted to the rotating shaft;
An idle gear rotatably fitted to the rotating shaft with a clearance between the sliding bearing and the outer peripheral surface of the sliding bearing;
A stopper provided on the rotating shaft and having an abutting surface abutting on one end surface of the slide bearing;
A gear transmission comprising a press-fit member press-fitted to the rotary shaft and having a contact surface that contacts the other end surface of the slide bearing,
At least one of the end face and the other end face of the slide bearing includes a frusto-conical surface continuing to the outer peripheral side
Of the contact surface of the stopper and the contact surface of the press-fitting member, the contact surface that contacts at least one of the one end surface and the other end surface of the slide bearing is in relation to the frustoconical surface of the slide bearing. A gear transmission characterized in that it is a frusto-conical surface having a complementarity.

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