JP2008064760A - Unidirectional gear, especially unidirectional gear for watche - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a unidirectional gear which can more readily restore to normal rotation, especially, a gear for watches. <P>SOLUTION: This unidirectional gear includes toothed drive gear (1) and toothed driven gear (3), in which the rear face (9) on a gear tooth (2) of the drive gear (1) contains a depression (10), defining both a 1st plane (11) and a 2nd plane (12) of the rear face (9) crossing an edge (13). The 2nd plane (12) is located in between the 1st plane (11) and the vertex (15) of the gear tooth (2) on the 1st plane (11); while the vertex (16) of a gear tooth (4) on the toothed driven gear (3) is the edge defined by a 3rd plane (17) and a 4th plane (18). At the blocking location of the gear, one tooth (4b) of the toothed driven gear (3) is set by the vertex (16) of the gear tooth (4b) on the toothed driven gear (3), brought into contact with the 1st plane (11) of one tooth (2b) on the drive gear (1), at the only contact point which practically matches with the edge (13) of the depression (10). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a one-way gear, that is, a gear in which a driven gear can be rotated by a driving gear only in one direction and two gears are prevented from rotating in the other direction.

  In conventional one-way gears, and in particular, timepiece gears, the prevention of rotation in a given direction is often dealt with by the wedges of one gear being wedged by striking against the teeth of the other gear. Thus, when it is desired to restore rotation in the other direction, a force is generated to remove the wedge stop of these teeth.

  An object of the present invention is to provide a one-way gear, particularly a timepiece gear, which can recover normal rotation more easily.

  For this purpose, a one-way gear is provided, the one-way gear comprising a toothed drive gear and a toothed driven gear, the rear surface of the tooth of the drive gear being the first surface and the second surface of the rear surface intersecting at the edge. Including a recess defining two surfaces, the second surface is located between the first surface and the apex of the tooth, and the apex of the tooth of the driven gear is an edge defined by the third surface and the fourth surface; At the gear blocking position, one of the driven gear teeth is on one first face of the drive gear tooth at the only contact point defined by the apex of the tooth of the driven gear and substantially coincident with the edge of the recess. Abut.

  One of the reasons for the anti-wedge effect seen in conventional one-way gears is the situation that causes a wedge stop due to tooth contact and elastic deformation, between one tooth of the drive gear and one tooth of the driven gear. This contact area is too close to the line connecting the centers of the gears, known as the “center line”. Occasionally, this wedge will also cause wear on the tooth tips of the drive or driven gear that pushes the other tooth, and the point of contact of these two teeth will be close to the centerline due to said wear.

  In the present invention, at the gear blocking position, the tooth of the driven gear and the first surface are pressed against each other only at the apex of the tooth of the driven gear and near the edge of the recess, i.e., away from the centerline. In addition, the tooth configuration provided by the present invention can avoid positive contact of the tip to a surface that causes wear.

Particular embodiments of the invention are defined in the appended claims 2-13.
Further features and advantages of the present invention will become apparent upon reading the following detailed description with reference to the accompanying drawings.

  Referring to the accompanying drawings, a one-way gear according to the present invention comprises a drive gear 1 with teeth 2 that are all identical and regularly arranged, and a driven gear 3 with teeth 4 that are all identical and regularly arranged; including. By “gear” is intended a gear in the original sense, or any rotating circular part such as a pinion.

  In the normal function of the gear, the drive gear 1 rotates in the direction indicated by the arrow F1, and the convex main surface 5 of the front face 6 of the tooth 2 can rotate the driven gear 3 in the direction indicated by the arrow F2. 4. Press the convex main surface 7 of the rear surface 8 and slide on it.

  The rear surface 9 of the tooth 2 has at its top a recess 10 defining a first plane 11 and a second plane 12 that intersect along the edge 13 and form an obtuse angle α protruding between them. The first plane 11 forms a landing between the second plane 12 and the lower surface 14 of the rear surface 9. The second plane 12 extends from the edge 13 to the edge-shaped vertex 15 of the tooth 2.

  The apex of the tooth 4 is an edge 16 formed by the intersection between the upper plane 17 of the rear face 8 and the slightly convex upper face 18 of the front face 19 of the tooth 4. Two further edges 20, 21 are caused by the intersection between the upper plane 17 and the convex main surface 7 of the rear face 8 and by the intersection between the slightly convex upper face 18 and the main plane 22 of the front face 19. Each is formed on a tooth 4.

  When the drive gear 1 is driven rearward, i.e., as indicated by the dotted arrow F3 in FIG. 2, the rear face 9 of the tooth 2a pushes the front face 19 of the tooth 4a. Because of the recess 10, the drive gear 3 is delayed and the apex of the tooth 4b directly in front of the tooth 4a (with respect to the normal direction F2) enters the recess 10 in the tooth 2b directly in front of the tooth 2a (with respect to the normal direction F1). Since the landing 11 of the tooth 2b is in the course of the tooth 4b, the tooth 4b hits the landing 11 and creates mutual blocking of the gears 1 and 3. The contact between the tooth 4b and the landing 11 and more generally the contact between the tooth 4b and the tooth 2b is a point contact, or more precisely a line contact, and the point or line of contact is Defined and substantially coincides with the edge 13 as defined by the faces 11, 12. In this blocking position of the gear shown in FIG. 2, the plane 17 of the tooth 4 b thus has a non-zero opening angle β between the landing 11 and non-zero. This angle β is so large that the contact between the planes 11 and 17 is considered a point (or line) contact, but small enough that the apex 16 of the tooth 4 is not sharp and pointed too much, ie the surface 17, at the apex 16. The angle θ defined by 18 is selected to be sufficiently large. The angle β typically has a value between about 2 ° and about 20 °. In the illustrated example, it is about 2 °.

  Thus, the contact between the tooth 2b and the tooth 4b is the only point located far from the line 23 connecting the centers of the gears 1 and 3, i.e. located at a large angular distance μ from the line 23 measured, for example, from the center of the driven gear 3. Or on line 16. Thus, the elasticity of the gears 1 and 3 reduces the risk that the teeth 4b will be wedged to the teeth 2b during blocking and helps easy recovery of the rotation of the gear 1 in the normal direction F1. It will also be noted that the direction of the landing 11 is such that the teeth 4b are not dragged while the normal rotation of the gear 1 is restored.

  A further advantage of the present invention is that the resting force of the landing 11 at the apex 16 occurs on the side of the surface 17 and thus away from the radial direction of the gear 3 passing through the apex 16. This helps limit the wear incurred by the apex 16 as the gear is used. This wear limitation is further reinforced by increasing the angle θ defined between the surfaces 17, 18 and typically greater than 90 °. From this point of view, it will be noted that the convex shape of the surface 18 allows a large angle θ to be obtained without compromising the cooperation between the teeth 2a, 4a.

  Also, as can be seen in FIG. 2, in the gear blocking position, the tooth 2a contacts the tooth 4a at a single point or line defined by the edge 21 and the plane 12, and the surfaces 12, 22 between each other are It has an angle δ that is not zero and opens toward the inside of the driven gear 3. This angle δ is so large that the contact of the planes 12 and 22 is considered to be a line (or point) contact, but is small enough that the edge 21 is not too sharp, ie, defined by the surfaces 18 and 22 at the edge 21. The angle ε is sufficiently large. The angle δ typically has a value between about 2 ° and about 20 °. In the illustrated example, the value is about 2 °. This configuration of surfaces 12, 22 avoids positive on-surface tip contact during blocking and allows tooth 2a to be released from tooth 4a without any effort while normal rotation is restored. To do.

  In addition to the aforementioned advantages, the gears 1, 3 according to the invention may be realized with standard gears. In the present invention, it is not necessary to use gears having different teeth, and it is not necessary to have irregular intervals.

FIG. 3 is a partial view of a one-way gear according to the present invention at a normal rotation position. FIG. 4 is a partial view of the one-way gear according to the present invention at a blocking position.

Explanation of symbols

1 Drive gears 2, 2a, 2b, 4, 4a, 4b Teeth 3 Driven gear 10 Recess 11 First surface 12 Second surface 13 Edge

Claims (13)

A one-way gear including a toothed drive gear (1) and a toothed driven gear (3), wherein the rear surface (9) of the tooth (2) of the drive gear (1) intersects at an edge (13) Including a recess (10) defining a first surface (11) and a second surface (12) of the rear surface (9), wherein the second surface (12) is formed between the first surface (11) and the teeth (2). The apex (16) of the tooth (4) of the driven gear (3), which is located between the apex (15) and the edge defined by the third surface (17) and the fourth surface (18), In the blocking position, one of the teeth (4b) of the driven gear (3) is defined by the apex (16) of the tooth (4b) of the driven gear (3) and substantially the edge (13) of the recess (10). In contact with a first surface (11) of one of the teeth (2b) of the drive gear (1) at the only matching point
One-way gear characterized by that. The first surface (11) and the third surface (17) are flat surfaces.
The one-way gear according to claim 1. In the gear blocking position, the first surface (11) and the third surface (17) form an angle (β) of less than about 20 ° at the contact point (16).
The one-way gear according to claim 1 or 2. In the gear blocking position, the first surface (11) and the third surface (17) form an angle (β) of about 2 ° at the contact point (16).
The one-way gear according to claim 3. The second surface (12) is a plane,
The one-way gear according to any one of claims 1 to 4. The fourth surface (18) is a convex surface,
The one-way gear according to any one of claims 1 to 5. The first surface (11) and the second surface (12) form an obtuse angle (α) at the edge (13) of the recess (10).
The one-way gear according to any one of claims 1 to 6. The third surface (17) and the fourth surface (18) form an obtuse angle (θ) at the apex (16) of the tooth (4) of the driven gear (3).
The one-way gear according to any one of claims 1 to 7. The third surface (17) forms an edge (20) with the other surface (7) of the rear surface (8) of the tooth (4) of the driven gear (3), and the fourth surface (18) 3) forming an edge (21) with the other face (22) of the front face (19) of the teeth (4);
The one-way gear according to any one of claims 1 to 8. In the blocking position, the second surface (12) of the other tooth (2a) of the drive gear (1) is the fourth surface (18) and the front surface (19) of the other tooth (4a) of the driven gear (3). Rests with respect to the other teeth (4a) of the driven gear (3) at the only contact point defined by the edge (21) formed by the other surface (22) of
The one-way gear according to claim 9. In the blocking position, the other face (22) of the front face (19) of the other tooth (4a) of the driven gear (3) is brought into contact with the other tooth (2a) of the drive gear (1) at the contact point (21). Forming an angle (δ) less than about 20 ° with the second surface (12) of
The one-way gear according to claim 10. In the blocking position, the other face (22) of the front face (19) of the other tooth (4a) of the driven gear (3) is brought into contact with the other tooth (2a) of the drive gear (1) at the contact point (21). And an angle (δ) of about 2 ° with the second surface (12) of
The one-way gear according to claim 11. The other surface (22) of the front surface (19) of the tooth (4) of the driven gear (3) is a plane,
The one-way gear according to any one of claims 9 to 12.

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