JP7428690B2 - gear - Google Patents

Description

The present invention relates to gears, and in particular to tooth shape and tooth pitch.

For example, Patent Document 1 is known as a technique for reducing noise when gears mesh with each other. In Patent Document 1, quietness is satisfied by improving tooth surface accuracy.

JP2012-096251A

By the way, in addition to Patent Document 1, it has been conventionally believed that improving the finishing accuracy of dimensions related to the shape of teeth is good for reducing noise and vibration during meshing. To briefly explain this point, Fig. 10 is a graph schematically showing the meshing sound (gear noise) of conventional gears, where the horizontal axis represents the frequency and the vertical axis represents the magnitude of sound vibration (vibration and vibration noise). represent. Referring to FIG. 10, it is understood that sound vibration increases at frequencies at regular intervals. This is because there is uniformity in the time difference between each tooth meshing in sequence, and this frequency is called the meshing frequency f of the gear, and depends on the number of teeth z of the gear, and is determined by the following equation. Sound vibrations with frequencies that are integral multiples of this frequency are called integer-order noise, and sound vibrations with frequencies that are non-integer multiples of this frequency are called non-integer-order noise.
[Formula 1] f =N/60×z
f: Gear mesh frequency [Hz] N: Gear rotation speed [rpm] z: Number of gear teeth [number of teeth]

When the gear noise shown in Figure 10 is input to a person's ears, it is difficult to say whether or not the person perceives the gear noise as unpleasant noise due to complex factors such as environmental and individual differences. It seems that at least the integer-order sounds shown in FIG. 10 are easily perceived by the human brain and recognized as noise. The reason for this is thought to be that the gap between the noise peak of integer-order noise and the noise bottom of non-integer-order noise is large.

The present inventor aims to reduce the noise gap by focusing on the gap between the noise peak of integer-order noise and the noise bottom of non-integer-order noise (hereinafter also referred to as noise gap), aiming at gear noise that is difficult for humans to perceive. This led us to the present invention.

To this end, the present invention provides a gear equipped with a plurality of teeth, in which a plurality of teeth are arranged in series as one set, and the set has a difference in the shape and/or pitch of adjacent teeth, It has one or more repetitions of such a set.

According to the present invention, the plurality of teeth do not have a uniform shape and a uniform pitch as in the past, but there are significant differences between the teeth that make up the set, so when the teeth are meshed with the mating gear and rotated, each tooth is arranged in the same order. Non-uniformity occurs in the time difference between the two. As a result, as shown in FIG. 9, the non-integer order noise increases and the noise gap decreases. Furthermore, the meshing sound generated when the gear of the present invention rotates while meshing with a mating gear is difficult to be perceived as noise by the human ear, unlike conventional gears. Regarding the gear of the present invention, the pattern of the plurality of teeth constituting the set is not particularly limited. The set is repeated in the circumferential direction of the gear.

The difference between the plurality of teeth constituting the set is at least one of various management items. For example, the plurality of teeth constituting the set may have different tooth profiles on their tooth surfaces, or may have different tooth trace shapes. Specifically, for example, there may be a difference in at least one of the tooth profile gradient, tooth profile unevenness, or other shapes in the tooth profile of the tooth surface. Alternatively, for example, there may be a difference in at least one of the tooth trace inclination, crowning center position, crowning amount, or other shapes in the tooth trace shape. Further, there may be a difference in the pitch between the teeth constituting the set, and specifically, for example, there may be a difference in the management item of single pitch, adjacent pitch, or cumulative pitch. Note that the tooth profile unevenness in the tooth profile of the tooth surface refers to forming the tooth surface so that it is rounded, for example, when looking at the tooth in the axial direction of the gear, and is also referred to as tooth profile rounding or tooth profile crowning. Crowning in a tooth trace shape refers to a tooth trace extending from one end to the other end in the axial direction of a gear, in which the central region of the tooth trace is bulged when viewed from both ends of the tooth trace. In the gear according to the present invention, since the plurality of teeth constituting one set have differences from each other, the differences are patterned within one set, and this patterned difference has reproducibility. According to the present invention, by repeating the set in the gear manufacturing process, the sets have reproducibility such that the sets have the same regularity, so that the gear can be efficiently produced.

The present invention also provides a gear-shaped cutting tool having a plurality of cutting teeth, in which the plurality of cutting teeth arranged in succession constitute one set, and the set has different shapes and/or pitches between adjacent cutting teeth. and one or more repetitions of such a set.

The shapes and pitches of the plurality of cutting teeth constituting the set of the cutting tool are managed using the same management items as the gears described above.

According to the cutting tool of the present invention, a gear in which the teeth arranged in the circumferential direction are different from each other can be efficiently manufactured by honing, skiving, gear shaper, or shaving.

As described above, according to the present invention, the gap between the noise peak of integer-order noise and the noise bottom of non-integer-order noise becomes smaller than before, the noise peak of integer-order noise is masked, and the rotating gear pair Even if the meshing sound reaches the human ear, it is difficult to perceive as noise or vibration. Furthermore, the cutting tool of the present invention enables mass production of the gear of the present invention. The gear of the present invention is suitably used in passenger cars with high quiet performance, such as electric cars.

FIG. 1 is a front view showing a gear according to a first embodiment of the present invention. It is an enlarged view showing a set of teeth of the same embodiment. It is a graph which shows the cumulative pitch significant difference of the same embodiment. It is an enlarged view showing a set of teeth of the same embodiment. 2 is a graph showing test results of sound vibration magnitude for Example 1 and Comparative Example 1. FIG. 7 is an enlarged view showing the contour shape and management dimensions of one tooth in the second embodiment of the present invention. 3 is a graph showing the test results of the magnitude of sound vibration for Example 2 and Comparative Example 2. BRIEF DESCRIPTION OF THE DRAWINGS It is a front view which shows the cutting tool which becomes one embodiment of this invention. It is a graph showing the magnitude of sound vibration of the present invention. It is a graph which shows the magnitude|size of the sound vibration of a prior art.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings. FIG. 1 is a front view showing a gear according to an embodiment of the present invention. The gear 10 of the present invention is an external gear having a plurality of teeth 11 on its outer periphery. The number of teeth 11 is 40, and 8 is included as a divisor of the number of teeth. Eight consecutive teeth constitute one set corresponding to the divisor. The gear 10 repeats this one set five times in the circumferential direction. In addition, as a modification not shown, the gear of the present invention may be an internal gear. Further, the number of teeth constituting a set and the number of sets constituting a gear may be changed arbitrarily.

I would like to add here that in general gears, the number of teeth does not have a common divisor other than 1, so that the teeth of one gear and the teeth of the other gear that mesh with each other are round robin. is preferable, and prime numbers are often used for the number of teeth. In the present invention, the number of teeth constituting one set is a divisor of the number of teeth of a gear, and in addition, the number of sets constituting a gear is a divisor of the number of teeth of the gear.

FIG. 2 is an enlarged view showing a set of teeth included in the gear shown in FIG. 1. As described above, one set G includes eight teeth, which is the divisor 8. The pitches of the teeth in one set G are not all uniform, but include intentional differences (significant differences) that exceed manufacturing tolerances so that they differ slightly with dimensional differences that are not perceivable to the naked eye. To facilitate understanding of the invention, significant differences are exaggerated in FIG. 2 and other embodiments (FIGS. 4 and 6) described below. In addition, in FIG. 2, the pitch teeth of a conventional gear are drawn with broken lines. The tooth pitches of conventional gears are all equal within predetermined tolerances.

As shown in FIG. 2, when the teeth 11 are compared among the teeth 11 constituting one set G, all the teeth 11 are not uniform but have intentional differences. Specifically, there is a significant difference in the pitch of the teeth 11. Referring to FIG. 2, when the pitches of the circumferentially adjacent teeth 111, 112, 113 are compared, it can be seen that there is a significant dimensional difference between the two. In this embodiment, management is performed using cumulative pitch. The cumulative pitch significant difference in this embodiment is expressed by cumulative pitch significant differences Pa, Pb, Pc, Pz, Py, Px, and Pw, with one tooth for which the cumulative pitch significant difference is 0 as a reference. Referring to FIG. 2, the cumulative pitch is calculated from the intersection of one tooth surface of one reference tooth 11 in the circumferential direction and the pitch measurement circle Cs on the circumference of the pitch measurement circle Cs. The cumulative pitch significant difference is a numerical value indicating how much it differs from the standard cumulative pitch. The standard cumulative pitch is the cumulative pitch when the pitches of adjacent teeth are all equal. The pitch measurement circle Cs is a circle that is smaller in diameter than the tip circle and larger in diameter than the root circle, and is coaxial with the arrangement of the teeth 11. It should be noted that the conventional teeth, represented by dashed lines, are arranged at a standard cumulative pitch. Note that as a modification (not shown), the one tooth serving as the reference for the cumulative pitch significant difference may be another tooth.

In this embodiment, the cumulative pitch significant difference has a regularity that is intentionally adjusted. Specifically, as shown in the graph of FIG. 3, the cumulative pitch significant difference Pc, Pb, Pa, 0, Pz, Py, Px, Pw of the teeth 11, 11, etc. arranged continuously in the circumferential direction is patterned according to an arbitrary function. All the teeth 11 of the gear 10 are arranged so as to repeat a plurality of sets (for example, five sets) with this pattern as one set. The cumulative pitch significant difference in this embodiment is regular based on a sine wave, as shown in the graph of FIG. The form of patterning can be freely set. The magnitude relationship of Pc, Pb, Pa, 0, Pz, Py, Px, and Pw is freely determined between the maximum value and the minimum value. For example, some numerical values among Pc, Pb, Pa, 0, Pz, Py, Px, and Pw may be equal. For example, Pc=Pa, Pw=0, and Pz=Px. The pattern of the patterned difference is not limited to the sine wave shown in FIG. It may have random variations in the rules or other patterns.

The gear 10 of the present invention may be managed by the cumulative pitch shown in FIG. 3 described above, a single pitch shown in FIG. 4, or adjacent pitches not shown. FIG. 4 is a diagram showing the single pitches Pe, Pf, Pg, Ph, Pi, Pj, Pk, Pl of the teeth 11, 11, . . . constituting one set G, and corresponds to FIG. 2. With reference to FIG. 4, the single pitch is the arcuate distance between the intersections of one circumferential tooth surface of the circumferentially adjacent teeth 11 and the pitch measurement circle Cs on the circumference of the pitch measurement circle Cs, The single pitch significant difference is a numerical value indicating how much it differs from the uniform standard single pitch Ps. A uniform standard single pitch is a value obtained by dividing the entire circumferential distance of the pitch measurement circle Cs by the number of teeth. It should be noted that the teeth of the conventional gear represented by the dashed lines are arranged at a uniform standard single pitch.

The single pitches Pe, Pf, Pg, Ph, Pi, Pj, Pk, Pl also have a deliberately adjusted regularity. For example, as shown in FIG. 3, the pitch is a sine wave, and when adjacent single pitches are compared, there is a difference. Referring to FIG. 4, it can be seen that, unlike conventional gears, the teeth 11 of this embodiment have a significant dimensional difference from the uniform standard single pitch.

In the embodiment shown in FIG. 4, the difference between the maximum value and the minimum value is a predetermined value within the range of 5 to 100 μm. Of course, this difference is larger than the tolerance allowed in manufacturing the gear 10. The same applies to the difference between the maximum value and the minimum value in the embodiments shown in FIG. 2 and FIG. 6, which will be described later. Note that if the difference between the maximum value and the minimum value exceeds 100 μm, it is not preferable because of durability problems such as wear. Further, if the difference between the maximum value and the minimum value is less than 5 μm, the noise gap becomes large, that is, becomes substantially the same as the conventional one, which is not preferable.

An embodiment of the present invention shown by a solid line in FIG. 2 was prototyped (Example 1). In addition, gears with a uniform pitch shown by broken lines in FIG. 2 were prepared (Comparative Example 1). A comparative test of the sound vibration levels of Example 1 and Comparative Example 1 was then conducted. Regarding the cumulative pitch of the teeth in Example 1, the difference between the maximum value and the minimum value is 30 μm. Regarding the cumulative pitch of teeth with a ratio of 1, the cumulative pitches of all teeth are all standard cumulative pitches. Common points between Example 1 and Comparative Example 1 are that the diameter of the gear tip circle is 85 mm, the diameter of the root circle is 73 mm, the tooth width is 20 mm, and the cumulative pitch that is the target value for manufacturing and the actual cumulative pitch. The amount of error (tolerance) is 10 μm or less. The mating gear with which Example 1 meshes and the mating gear with which Comparative Example 1 meshes are common gears, and are conventional general gears with a standard cumulative pitch. With the gear meshed with the mating gear, it was rotated at a rotational speed of 500 rpm and the meshing sound vibration was measured. At the same time, the meshing sound was confirmed with the human ear.

FIG. 5 is a graph showing the measurement results of meshing sound vibration, where the solid line represents Example 1 and the broken line represents Comparative Example 1. In the graph, the horizontal axis represents the frequency [Hz], and the vertical axis represents the magnitude [dB] of the meshing sound vibration. It is understood that in Example 1 (solid line), the non-integer order noise is larger than in Comparative Example 1, and the noise gap is smaller. When confirmed with human ears, Comparative Example 1 sounded louder than Example 1.

Next, a second embodiment of the present invention will be described. FIG. 6 is a front view showing the second embodiment, and is an enlarged view showing extracted teeth constituting one set. In FIG. 6, (A) represents a set of teeth 11, and (B) represents a contrast between the teeth 11. In the second embodiment, regarding the plurality of teeth 11 constituting the gear 10, the tooth profile shape of each tooth 11 is made to have a slight variation, that is, a significant difference.

As a specific example, the management item that causes a difference in the tooth profile shape is to make the tooth profile gradient of the tooth profile 12 on the tooth surface of the tooth 11 different from each other, and is an unmodified shape calculated on a theoretical tooth profile curve, or With respect to the standard tooth profile 12s, which is a shape to which a modification amount set by the designer has been added based on the theoretical tooth profile curve, the actual tooth profile 12 is made to have a steeper tooth profile slope by a significant difference Sb, Sc, or Sa. The designed tooth profile is such that the tooth profile slope is made gentle by the difference Sb, Sz, or Sy. Then, the differences in the tooth profile 12 of each tooth 11 are patterned into one set G.

Significant differences in tooth profile gradients on tooth surfaces have a deliberately adjusted regularity. With reference to FIG. 6(A), significant differences in tooth profile gradients Sc, Sb, Sa, 0, Sz, Sy, Sx in the tooth profiles of the tooth surfaces of the teeth 11, 11, etc. that are continuously arranged in the circumferential direction , Sw are patterned according to an arbitrary function. All the teeth 11 of the gear 10 are arranged so as to repeat a plurality of sets (for example, five sets) with this pattern as one set. The significant difference in the tooth profile gradient in the tooth profile of the tooth surface of this embodiment may be regular based on a sine wave, as shown in the graph of FIG. In FIG. 3, Pc, Pb, Pa, 0, Pz, Py, Px, and Pw can be read as Sc, Sb, Sa, 0, Sz, Sy, Sx, and Sw, respectively. Note that some numerical values among Sc, Sb, Sa, 0, Sz, Sy, Sx, and Sw may be equal. For example, Sc=Sa, Sw=0, and Sz=Sx. The pattern of patterned differences is not limited to the sine wave shown in FIG. 3, but may also include triangular waves, square waves, polygonal waves, other regular waves (not shown), or random significant differences in tooth profile shapes within one set. It may also be a random tooth profile with significant differences or other patterns.

For management purposes, the significant differences Sc, Sb, Sa, 0, Sz, Sy, Sx, and Sw are circumferential dimensions (linear length or circular arc length) in the measurement circle Cr located between the tooth tip circle Ct and the tooth profile control circle Cd. It is. The measurement circle Cr is, for example, a circle whose radius is a predetermined value included in the range of 50 to 95% on the outer diameter side of the tooth profile management circle Cd, where the difference in radius between the tooth tip circle Ct and the tooth profile management circle Cd is 100%. The pattern of significant differences Sb, Sa, Sz, and Sy in one set G conforms to FIG. 3. In order to facilitate understanding of the invention, in FIG. 6, significant differences in tooth profile shapes are exaggerated and the measurement circle Cr is set to 100%.

It should be noted here that if the lower limit is less than 50%, the control range is too small and the noise gap, which is an issue of the present invention, cannot be sufficiently reduced. Moreover, if the upper limit value exceeds 95%, the management will not be reflected in the actual product, and the noise gap, which is a problem of the present invention, will not be sufficiently reduced.

The significant differences Sb, Sa, Sc, Sz, Sx, and Sy are predetermined values within the range of 2 to 40 μm. Of course, this difference is larger than the tolerance allowed in manufacturing the gear 10. If the significant difference Sb, Sa, Sz, Sy exceeds a predetermined range, it is undesirable due to durability issues such as wear, and if it falls below the predetermined range, the noise gap becomes large, which means that it is not suitable for conventional gears. I don't like this because they end up being the same.

As a modification (not shown), the management item that causes a difference in the tooth profile shape may be the tooth profile slope of the tooth 11, or other management items related to the tooth profile classified under JISB1702 "tooth profile error". Alternatively, as another modification (not shown), the tooth trace shapes of the teeth 11 may be made different. Management items that cause differences in tooth trace shape include, for example, crowning center position, tooth trace inclination, other crowning, and various other tooth trace-related management items classified under JISB1702 "tooth trace error". It may be an item.

An embodiment of the present invention shown by a solid line in FIG. 6(A) was prototyped (Example 2). In addition, a gear with a uniform tooth profile indicated by a broken line in FIG. 6(A) was prepared (Comparative Example 2). A comparative test of the sound vibration levels of Example 2 and Comparative Example 2 was then conducted. Common points between Example 2 and Comparative Example 2 are that the diameter of the gear tip circle is 85 mm, the diameter of the root circle is 73 mm, the tooth width is 20 mm, and the error between the tooth profile that becomes the target value for manufacturing and the actual tooth profile. The amount (tolerance) is 10 μm or less. The mating gear with which Example 2 meshes and the mating gear with which Comparative Example 2 meshes are common gears, and are conventional general gears with a uniform tooth profile. With the gear meshed with the mating gear, it was rotated at a rotational speed of 500 rpm and the meshing sound vibration was measured. At the same time, the meshing sound was confirmed with the human ear.

FIG. 7 is a graph showing the measurement results of meshing sound vibration, where the solid line represents Example 2 and the broken line represents Comparative Example 2. In the graph, the horizontal axis represents the frequency [Hz], and the vertical axis represents the magnitude [dB] of the meshing sound vibration. It is understood that in Example 2 (solid line), the non-integer order noise is larger than in Comparative Example 2, and the noise gap is smaller. When confirmed with the human ear, Comparative Example 2 sounded louder than Example 2.

Next, a cutting tool for producing the gear of this embodiment will be explained.

FIG. 8 shows a cutting tool 60 for cutting the gear 10 shown in FIG. The cutting tool 60 is in the shape of an external gear, and has cutting teeth 61 having the same shape as the teeth of a gear. In addition, as a modification not shown, the cutting tool of the present invention may have an internal gear shape.

Similarly to the gear 10 described above, the cutting tool 60 shown in FIG. repeat. In the embodiment shown in FIG. 8, the total number of teeth is 40, the number of teeth in one set is 8, and 5 sets are repeated. In manufacturing the gear 10, the cutting tool 60 used in high-precision cutting and grinding in the finishing stage has a set of cutting teeth 61 in the same number as the number of teeth in the set that the gear 10 has, and has one or more sets of cutting teeth 61. Multiple sets of cutting sections are repeated in the circumferential direction.

The contour shape of the cutting tooth 61 corresponds to the tooth 11 described above. In other words, like a pair of gears meshing with each other, the cutting teeth 61 have the shape of the teeth of a gear made so that the contour shape of the locus drawn by the cutting teeth 61 when machining the gear matches that of the teeth 11. All of the cutting teeth 61 are patterned with regular differences as shown in FIG. 3, so that adjacent cutting teeth 61, 61 have slightly different shapes.

The cutting tool 60 rotates together with the gear to be machined while being pressed against the gear to be machined. At this time, the cutting tool 60 removes excess meat from the surface of the gear to be machined, and specifically performs finish cutting, grinding, polishing, and dressing to form the teeth 11 of set G. The cutting tool 60 is also called a dresser, a grindstone, a pinion cutter, or a shaving cutter because it is used for gear honing, skiving, gear shaping, or shaving.

Although the embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to the illustrated embodiments. Various modifications and variations can be made to the illustrated embodiment within the same scope as the present invention or within an equivalent scope. For example, some configurations may be extracted from one embodiment described above, some other configurations may be extracted from other embodiments described above, and these extracted configurations may be combined.

The invention is advantageously used in machine elements.

10 Gear, 12 Actual tooth profile of tooth surface (tooth profile gradient), 12s Standard tooth profile, 60 Cutting tool, 61 Cutting tooth, Cs Intermediate circle, G 1 set of teeth.

Claims (3)

A gear having a plurality of teeth,
A plurality of teeth arranged in succession constitute one set,
The set has a difference in shape and/or pitch of the adjacent teeth that exceeds a manufacturing tolerance,
A gear having a plurality of repetitions of the set. The difference is
Regarding the shape, the tooth profile slope in the tooth profile of the tooth surface, the tooth profile unevenness, the tooth trace inclination in the tooth trace shape, the crowning center position, the crowning amount,
The pitches include single pitch, adjacent pitch, cumulative pitch,
The gear according to claim 1, wherein the difference is in at least one selected from: The gear according to claim 1 or 2, wherein the plurality of circumferentially continuous differences within the set have patterned regularity.

Images