A deceleration device for a vehicle seat comprises an external gear comprising teeth with tops projecting radially outward. A tooth of the external gear comprises a straight portion and a critical cross-section located in a dedendum flank of the tooth of the external gear. The straight portion is provided in a vicinity of the critical cross-section and a thickness of the straight portion becomes linearly larger toward a root of the tooth.

Electric motors are disclosed. The motors are preferably for use in an automated vehicle, although any one or more of a variety of motor uses are suitable. The motors include lift, turntable, and locomotion motors.

A gear device includes a first gear, a second gear, and a third gear. The second gear is constituted of first meshing teeth that mesh with teeth in a first row of teeth of the first gear, second meshing teeth that mesh with teeth in a second row of teeth of the first gear, third meshing teeth that mesh with teeth in a third row of teeth of the third gear, and fourth meshing teeth that mesh with teeth in a fourth row of teeth of the third gear. The helix directions of the first meshing teeth and the third meshing teeth are the same direction. The helix directions of the second meshing teeth and the fourth meshing teeth are the same direction.

A gear keeping the bending stress at the dedendum from becoming locally high at the time of power transmission and thereby raising the dedendum bending strength is provided. The radius of curvature is maximum at a critical section position determined by the Hofer's 30 tangent method. Both of the radii of curvature from the critical section position to the first and second connecting points X1 and Y1 are constant or decreasing. In the dedendum line segment 23, there are the points A1 and B1 where the radius of curvature is smaller than the critical section position. In the dedendum line segment 23, the maximum radius of curvature is 3 times or less the minimum radius of curvature. By a cross-sectional view, the critical section position is part of an arc, and the arc extends to the two sides of the critical section position. Due to this, the maximum bending stress becomes smaller and improvement of the dedendum bending strength can be realized.

A gear including plural teeth 3 to mesh with teeth of a corresponding gear to thereby transmit a rotational motion is provided. A form (b) of a tooth root side of each tooth 3 includes: a first curved surface c that is smoothly connected to a tooth surface a having an involute curve and has a profile expressed by a curve that is convex in an inverse direction of the involute curve of the tooth surface a; and a second curved surface d that is smoothly connected to the first curved surface c and has a profile defined by a hyperbolic function having a curve being convex in the same direction as the first curved surface c. It is possible to reduce a stress generated on the tooth root side at the time of meshing with teeth of the corresponding gear and thus to increase the strength of the teeth.

The present application discloses an internal engagement transmission mechanism, comprising an outer wheel and an inner wheel. The outer wheel is provided with outer wheel inner teeth, and comprises an outer wheel inner tooth crest and an outer wheel inner tooth waist. The inner wheel is provided with inner wheel outer teeth, and comprises an inner wheel outer tooth crest and an inner wheel outer tooth waist. The inner wheel and the outer wheel form an internal engagement transmission through the inner wheel outer tooth waist and the outer wheel inner tooth waist. The outer wheel inner tooth waist and the inner wheel outer tooth waist are curved surfaces which have the same shape and are coincident. The inner wheel outer tooth waist and the outer wheel inner tooth waist form surface contact engagement, and the contact area between the inner wheel outer tooth waist and the outer wheel inner tooth waist gradually increases to a maximum value as the inner wheel rotates, and then gradually decreases. The internal engagement transmission mechanism of the present application can reduce stress concentration when the inner wheel is engaged with the outer wheel and improve the service life of teeth.

Provided is a herringbone planetary gear transmission device with a constant meshing characteristics constructed tooth pair, which relates to the technical field of gear transmission. The transmission device includes a sun gear with a constructed tooth pair, a planetary gear with a constructed tooth pair and an internal gear with a constructed tooth pair based on conjugate curves. Normal tooth profiles of the gears with a constructed tooth pair in the present disclosure are all the same combined curve and can be machined by using the same cutter. A common normal at an inflection point or a tangent point of the curve passes through a pitch point of a meshing gear pair, and a sliding ratio of the meshing gear pair is adjusted according to an adjusted position of the inflection point or the tangent point. A contact ratio of the meshing gear pair is designed as an integer.

A gear system includes gears that each have a tooth flank profile that includes a convex addendum and a concave dedendum, and when in mesh satisfy the Euler Savory equation for conjugacy with contact over the entire tooth flank such that lines of contact are unbroken. The portion between the addendum and dedendum is an involute or other geometric curve.

A gear transmission including: a plurality of gear wheels having a different diameter meshing with each other, at least one first driving gear wheel activated in rotation about its own axis, and at least one second driven gear wheel meshing with the first gear wheel, teeth being asymmetrical, with active sides conjugate with one another inactive sides of the teeth of the wheels not being conjugated with one another, and the inactive side is configured so that the radius passing by a tip of the teeth is substantially tangent to the inactive side or intersects the inactive side.

A gearbox comprising an internal-external gear pair having a small tooth-difference, the internal-external gear pair comprising: an internal gear arranged about an internal gear axis and having a first number of internal gear teeth; and an external gear having an external gear axis arranged to orbit the internal gear axis and having a second number of external gear teeth, the external gear being arranged to engage with the internal gear teeth; wherein the small tooth-difference is less than a fifth of the number of internal gear teeth; and wherein the internal gear teeth and the external gear teeth have an involute shape with no profile shift, or with a profile shift below a value at which the working pressure angles of the internal-external gear pair would exceed, by more than 20%, a nominal pressure angle of the internal-external gear pair if no profile shift were applied.