SI22871A - Slant-toothed cylinder-shaped gearwheel pair for uniform power transmission - Google Patents

Abstract

The slant- toothed cylinder-shaped gearwheel pair for uniform power transmission is based on the special shape of the lateral side of teeth (3) which enable a uniform power transmission from the driving (1) to the driven gearwheel (2). The operation principle of these gearwheels is based on the fact that the power (force F) is transferred via lateral helices, which keep connecting at contact points (Pd and Pa). On each of two contact points there is one helix of the lateral side of teeth of the driving gearwheel ((19) for (Pa) and (18) for (Pd)) and one helix of the lateral side of the teeth of the driven gearwheel ((21) for (Pa) and (20) for (Pd)). The helices of the teeth of the driving gearwheel (1) push the helices of the driven gearwheel (2) around the kinematic axis of the gearwheels, while the contact points (Pd and Pa) are rolling from the front radial plane towards the back radial plane parallel to the kinematic axis of the gearwheels (C). Regarding this, the first contact point in the rotating direction slightly overruns the other contact point. The contact points (Pd and Pa) are in diametric mutual position on the sliding circle (8) with kinematic pole (C) in the middle. The contact surfaces of the lateral side of teeth of the driving gearwheel are sliding along the lateral parts of teeth of the driven gearwheel on the sliding circle (8) without crossing the kinematic axis. This creates conditions that the magnitude of forces and the sliding conditions on the way from the front plane to the rear plane of the gearwheels does not change therefore the transmission of force from the driving to the driven gearwheel is uniform. Also important is the fact that the force is always transferred via two contact points, therefore their load is smaller. Both contact points are in their cross section of concave-convex shape, while in the rolling direction they are convex-concave, therefore the conditions for an ellipsoid shape of the distribution of pressure at the contact surface are provided.

Description

Bevel gear cylindrical gear wheel for even power transfer

The subject of the invention is an oblique toothed cylindrical gear pair, which is shown in Fig. 1 in the frontal plane and comprises a gear with a gearwheel of a gearwheel (1) and a gearwheel of a driven gearwheel (2) in which power is transmitted uniformly from the gearing to the driven gearwheel. The gears in such a gear pair have the same module, as a rule, different tooth numbers and the same angle of inclination, but in opposite directions of the thread, one gear with the left and the other with the right.

Scope and core of the problem

The transfer of energy from energy to work machines is present in all fields of mechanical engineering and represents the engine of modern civilization. The development tendencies of energy machines are directed to higher rotational speeds (gas turbines, internal combustion engines, electric motors), greater power transfer, better efficiency, etc. In the case of working machines, however, the speeds must be adapted to the operating conditions, and therefore, speed converters are used, including gearboxes, which are a narrower field of the invention. Gearboxes are used in virtually every field of technology to convert speeds from minimum to maximum power, from small to large gears and from small to very high speeds. From this broad field of technology, we will specifically limit ourselves to cylindrical gears with bevel teeth for transmitting high-power rotation occurring e.g. heavy industrial plants, large work machines, oil pumping plants and large wind farms.

The results of extensive scientific research and technological developments in the field of gearboxes are published in widely known, very extensive literature from the most technically advanced countries and are described in the textbooks of authors from renowned universities from Europe, Japan and the USA. Professional associations of leading industrialized countries have developed extensive ISO standards for gear sizing and control within the international ISO organization, and there are still differences of opinion on gear sizing for tearing resulting from the conversion of friction to heat. The present invention relates to a uniform friction load on the flanks of the teeth resulting from friction or sliding speeds. In this area, dimensioning of gears is still an incomplete chapter (integral or flash temperature method). In the present invention, however, we propose such a flank of teeth that allows even load transfer, even glide, less friction and less contact loads.

Description of the new solution

The toothed tooth is a cylindrical gear pair, shown in Fig. 1 in the frontal plane, comprising a gear (1) and driven (2) gear. In the present invention, the tooth profiles (3) of the gears in the radial plane are composed of a circular arc of the tooth tip (4) and of a circular arc of the tooth root (5), where the tooth tip arc is part of the tooth tip circle (6) and the tooth root arc the tooth root circle (7). The drive gear has a drive kinematic cylinder (9) and the driven gear has a driven kinematic cylinder (10), which are connected at a kinematic point C through which the center of the gear (11) also passes. The shape of the tooth flank in the vicinity of the kinematic cylinder (12) is determined by the tool in the manufacture of the individual gear according to the shape of the profile of the basic gear (13) shown in Figure 2.

Power or. the force F transmitted from the drive pinion (1) to the driven pinion (2) is transmitted through two concave-convex contact surfaces, that is, through contact point P _a and contact point P _d . The contact point P _{d is} formed by the convex profile of the driven tip of the driven sprocket and the concave profile of the tooth root of the sprocket, and the contact position P _a is formed by the convex profile of the tip of the gear sprocket and the concave profile of the root of the driven sprocket tooth. The contact surfaces P _a and P _d lie on the sliding circle (8), have common normals, diametrically opposite the kinematic point C. The distance of the contact points is determined by:

P _a - P _b = m - π · cos a where m is a module; α - angle bounding the tip of the apex and the root of the tooth root (Figure 2); m-π = p = e + s, p is the tooth division, which is divided by s - the thickness of the teeth and e - the width of the gap between the teeth.

The gears of the present invention can be manufactured on any gear machine with a tool corresponding to the profile of the basic gear (13) and shown in Figure 2. The width of the gear gap k m-π corresponds to the thickness of the gear tooth s and the thickness of the gear tooth (1 -k) km-π corresponds to the width of the gear gap e. The arc ED, which is part of the circle of the tip of the tooth (6), forms the root part of the side of the tooth of the gear (4) and the arc GF, which is part of the circle of the root of the tooth (7), forms the upper part of the side of the tooth of the tooth (5). The circular arc (14) centered at Oj is tangentially connected at point 1 to the root circular arc El of the gear tooth and at point 2 to the tip 2G 'of the tip of the gear tooth. The bow (17) connects the right and left flanks of the tooth with the radius p. The tangential connection of all three arches represents the smooth edge of the cutting tool. However, if we want a deeper gap DF 'between the tooth tip of the gear tooth (4) and the root of the tooth (5) we make a connecting arc (15) with the diameter of the circle of the tip of the tooth (6) through points D and F. The bottom of the tooth gap (16) is bounded by a straight line at a depth h equal to or greater than the gear module. The difference between the thickness of the gear teeth s and the width of the tooth gap e is determined by the coefficient k <0.15.

The gear teeth of the present invention are formed by the gradual cutting of a workpiece with a tool whose base profile corresponds to the profile of the gear (13) of Fig. 2 such that the center of the gear (11) is rolled up after each cut through the rolling circle (9) of the cutting gear for this is followed by the next cut. The process of rolling method of manufacture is shown in Figure 3 with the discrete positions of the gear profile (16) shown in dashed lines. When the kinematic point C at the center of the sprocket (11) reaches the kinematic point "C" on the kinematic cylinder (9), the blades of the circular arches of the gear (tool) produce the shape of the tip of the tooth (4) and the root of the tooth (5). This is the position of the gear (tool), in which the production of a circular arc of the tip of the gear tooth is completed, which is equal to the circular arc of the root of the gear tooth, and at the same time the circular arc of the root of the gear tooth, which is identical to the circular arc of the tip of the tool tooth, is completed. Therefore, all gears made with the same tool (same gear) have the same arches of the tips of the teeth (4) and the same arches of the root teeth (5). The part of the blade formed (formed) on the pinion by the connecting bow (14) or (15) forms the side profile of the tooth (12) (see Figure 1) between the arches of the tip (4) and the root of the tooth (5). The side profile of the tooth (12) reduces the thickness of the tooth in the area of the rolling circle and prevents the contact of the flanks of the teeth in the radial plane on the path from contact P _d to contact P _a , as shown in Figure 4.

Figure 1 shows that the force F is transmitted from the drive gear to the driven gear via the contacts P _d and P _a . Since the gears are oblique, the flanks of the teeth are helical, so the two contact points are located on the two screws shown in Figure 5. The contact point P _d thus corresponds to the screw (18) running along the side of the root of the gearing tooth and the screw ( 20), which runs along the side of the top of the tooth of the driven sprocket. The same applies to the contact point P _{a, a} helix (19) extending along the side of the top of the gearwheel and a helix (21) extending down the side of the root of the driven gear tooth. When rotating, the drive gears (18) and (19) push the drive gears (20) and (21) in the direction of rotation. The contact points P _d and P _a located at the intersections of the helixes move from the leading radial plane to the dorsal radial plane at a velocity in _r , due to the rolling of the gears of the driven gears. While the gear tooth flank at the contact points P _d and P _a rolls along the side of the driven tooth in the axial direction at a speed in _r , the tooth of the gear wheel slides on the sliding circle along the side of the driven gear tooth with a sliding speed in _g .

From Fig. 5 we can see that the toothed cylindrical gears, for uniform transfer of power at the contact points P _d and P _a, transmit motion in a uniform rotation, and thus also force evenly from the front to the back of the gears, which is repeated cyclically from the tooth with each engagement of the pair of teeth. to the tooth. In evolutionary gears, at the kinematic point the slip direction changes and its velocity increases with distance from the kinematic point, as shown in Figure 6a. In evolutionary gears, the size of the friction part changes, and thus the value of the contact temperature! 4fi _a , which increases with greater distance from the kinematic point C. In some operating conditions, there is a risk that the flash temperature (9 _fla ) exceeds the permissible limit against tearing, it can cause serious damage to the scuffing.

For oblique toothed cylindrical gears for uniform power transfer, the circumferential force is divided into two contact points, so the pressure at the individual contact points is lower and is the same throughout the width (Figure 6b). The contact points from the kinematic point are shorter than those of the evolution gears, thus reducing the sliding speed, reducing the friction work and reducing the risk of gear damage.

A brief presentation of the pictures

FIGURE 1 shows a pair of tapered cylindrical gears for even power transfer. The tooth profiles of both gears are shown. The positions of the two contact points Pa and P _a through which the load is transmitted are indicated. The position of the contact points with respect to the kinematic point C and the slip circle (7) through both contact points centered at point C are also presented.

FIG. 2 shows the structure of the gear profile (13), which must be matched by the gearing tool of the toothed cylindrical gears for uniform transmission of power. The lateral profile of this pinion (3) consists of a circular arc of the tip of the tooth (5), a circular arc of the root of the tooth (4) and a connecting arc 14 or 15. The thickness of the tooth of the pinion (1-k) m ^ produces the gap of the tooth EPM gear, the thickness of the gap the km-π gears, however, form a gear tooth.

FIG. 3 shows how a gear blade gradually cuts the workpiece and rolls its center line (11) along the kinematic circle (9) to form the gear teeth. One can see how the root of the sprocket forms the tip of the tooth (4) of the oblique cylindrical sprocket for even power transfer, and how the tip of the sprocket tooth forms the root of the tooth (5) of that sprocket. Thus, in the case of gearing, the profile of the top and the root of the tooth of the gear wheel get the shape of the profile of the root and top of the gear. It follows that all gears made with the same tool (same gear) have the same tip profiles and the same tooth root profiles.

FIG. 4 shows how the radial plane of the driving tooth and the driven tooth of the driven pinion of a pair of tapered cylindrical gears move in order to transfer power uniformly from contact point P _d to contact point P _a without touching it. Since the teeth of the gear and driven gear teeth do not touch each other along this path, they are not loaded and do not cause friction.

FIG. 5 illustrates kinematic conditions of motion and load transfer between the gear and driven gears; a view of the gear pair in axial direction A and plan B. is shown. Given that the gear teeth are oblique, both contact points P _d and P _a each their pair of screws extending down the tooth of each of the two gears along the entire length of the teeth from the frontal to the dorsal radial plane. Each helix has a certain width of contact which, when transmitting power, travels with the contact point P _d or P _a on its own path, which, however, is parallel to the kinematic axis of the gears through point C. The helices each lie on their own base cylinder, so they have different angles of rise β _Ρ with associated torsional bend radius τ. The gearwheel has helixes 18 and 19 and the driven gearwheel has helixes 20 and 21. Both contact points travel at the same speed in a direction perpendicular to the radial plane.

FIG. 6 shows the course of the contact loads and the velocity of the sliding velocities, and consequently also the course of the formation of temperature ignitions (8fi _a ) along the gearbox of the evolution gears and the conditions formed along the helixes of the oblique cylindrical gears for uniform power transfer. In evolutionary gears, the slider runs through the kinematic point C, where forces are transmitted only roller without sliding, but at the beginning and at the end of the sliding, the sliding speeds can be large, and accordingly the friction and heating of the sliding surfaces (d _fla ) change. Conversely, in the case of oblique toothed cylindrical gears, the load is transferred evenly between the flanks of the teeth in order to transfer the load force evenly, with more contact surfaces and less slip, as well as the load on the flanks of the teeth being divided into two contact points. Therefore, the surface heating (3fi _a ) is smaller, uniform over time and does not contain extremely hot spots.

Claims (7)

PATENT APPLICATIONS 1. An oblique toothed cylindrical gear pair characterized in that it comprises a gear sprocket (1) and a driven sprocket (2), in which the flanks of the tooth (3) have a circular arch of the tooth (4), a circular arc of the root of the tooth (1). 5), wherein the circular arch of the tooth tip is part of the upper circle (6) and the arch of the dental root is part of the root circle (7), where the two circles have a common center, with the flank of the tooth tip (4) joining the flank of the tooth root (5) on a sliding circle (8) whose center is located in the kinematic pole (C). 2. A toothed cylindrical gear wheel for even power transmission according to claim 1, characterized in that the gearwheel teeth (1) have the same upper circle (6) as the driven gear (2), and therefore the circular arches of the top teeth are driven and driven. gear teeth are the same, and the teeth of the gearwheel (1) have the same root circle (7) as the teeth of the driven sprocket, so the root circular teeth of the gearwheel and driven gears are the same, and the force (power) is transmitted from the gearing to the driven sprocket via two contact positions P _a and P _d lying on opposite sides of the sliding circle (8). 3. A toothed cylindrical gear pair for uniform power transfer according to claims 1 and 2, characterized in that the profile of the gear tooth (13) for gearing these gears consists of four arches, namely: (a) a circular arc of the root of the gear tooth (4) ), which is equal to the circular arc of the top of the gear tooth, (b) from the circular arc of the top of the gear tooth (5), which is equal to the circular arc of the root of the gear tooth, (c) from the connecting arc between the circular arc of the top of the tooth and the circular arc of the root of the gear tooth (14,15) and (d) from the connecting arc between the right and left flanks of the gear tooth (17), wherein the thickness of the gear tooth corresponds to the size of the gear gap (e) and the gear gap corresponds to the thickness of the gear tooth (s) and the circle of the tip ( 6) and the circle of the root of the tooth (7) are the same for the pinion and for the gears, with the center of the pinion (11) passing through the center of the sliding circle (8). 4. A toothed cylindrical gear pair for uniform power transmission according to claims 1, 2 and 3, characterized in that the gear tooth shape of such a gear pair is formed by a rolling manufacturing process with a tool corresponding to the gear profile (13), wherein (11) rolls along the kinematic circle (9) without sliding, and the tool blade gradually cuts the flanges of the gear teeth with a gradual cutting, and when the kinematic pole C at the center of the gear and the kinematic pole C on the kinematic circle intersect, they reach the top of the tooth (4); the root of the tooth (5) has the final shape, namely the profile of the tip of the tooth of the pinion takes on such a bow (4) as the root of the tooth of the pinion, and the profile of the root of the pinion of the tooth such arc (5) as the top of the tooth of the pinion, arc (14) or the bow (15) on the sprocket forms a deepening of the side profile of the sprocket tooth in the area of the kinematic circle. 5. A toothed cylindrical gear pair for uniform power transfer according to claims 1, 2, 3 and 4, characterized in that, with these gears having a certain module and a certain angle of inclination, β is an arc defining the side profile of the tip of the tooth (4) and is the part of the circle of the tooth tip (6) and the arch defining the profile of the tooth root flank (5) and being part of the circle of the tooth root (7) provided that the gears are made with tools of the same gear profile (13) in all the gears the radius of the arch of the top of the teeth is smaller than that of the root of the teeth, which means a concave-convex fit of the flanks of the teeth, which is the same at both contacts (P _a ) and (P _d ). 6. A toothed cylindrical gear pair for uniform power transfer according to claims 1, 2, 3, 4 and 5, characterized in that the tooth flanges of such a gear pair in the radial plane on the path from contact point P _d to contact point P _a have no contact due to deepening of the flanks of the teeth in the area of the kinematic circles (12) formed by the connecting arc (14) or (15) on the flank of the flanged tooth, so that the flanges of the teeth (in this region) are not stressed and friction free. A toothed-toothed cylindrical gear pair for uniform power transmission according to claims 1, 2, 3, 4, 5 and 6, characterized in that the movement and loads are transmitted from the gear to the driven gear by rolling the side gears of the gear gear teeth (18) ( 20) along the lateral screws of the teeth of the driven gear (19) (21) at a velocity (in _r ), with Pa and P _a sliding along the sliding circle (8) at a constant sliding speed (in _g ),), for a uniform load and evenly friction over the entire width of the gear teeth, even the thermal loads are uniform.