JPS61290241A - Brake rotor inhibiting harmonic vibration and manufacture thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a brake rotor and a method for manufacturing the same, and more particularly to a ventilated disc brake rotor configured to suppress harmonic vibrations during braking. .

[Conventional technology]

The vibration of the brake rotor during braking operations, when allowed to resonate at the acoustic harmonic frequency, causes a loud and irritating "squeal". This problem occurs in conventional drum and disc brake systems. Prior art attempts related to this problem include:
Utilizing sound-deadening inserts or fillings in the rotor (drum or disc) structure;
Or it involves the use of special material compositions in the brake pads.

In the special environment of ventilated disc brake rotors, U.S. Pat.
ay) specification and U.S. Patent No. 4,379,501 (Hagiwara + et al.) disclose a technique of arranging a variable pattern of cooling fins around the rotor in order to damp the vibrational harmonic resonance pattern.
In the former US patent, the rotor periphery is divided into equiangular segments, and the spacing between the cooling fins of each segment is random or non-repetitive. In the latter US patent, it is attempted to make the wall thickness of the cooling fins around the rotor and the spacing between the fins irregular or non-uniform.

[Problem to be solved by the invention]

It is an overall object of this invention to provide an improved technique for damping vibrational harmonics and reducing irritating squealing in both drum and disc brake rotors.

Another object of the invention is to provide a brake rotor that maintains the desired balance, strength and heat dissipation capabilities while having enhanced vibration damping capabilities.

Yet another object of the present invention is to provide a method for manufacturing the aforementioned rotor.

Another special object of the invention is to provide a ventilated brake system having a structure that reduces or eliminates brake squeal.
To provide a disc brake rotor.

The invention, together with additional objects, features and advantages thereof, includes:
It will be understood from the following description, the appended claims, and the accompanying drawings.

[Specific Means for Solving the Problems] Figures 1 and 2 show a ventilated disc brake rotor 20, in which a pair of flat annular friction rings or cheeks 22, 24 are arranged in a circular manner with respect to each other. They are spaced apart by circumferentially arranged rows of radially extending angularly spaced ventilation fins 26. Center mounting is on surface 28
is integrated with the friction ring 22, and the rotor 2
Suitable openings 32,34 are provided for mounting the 0 to the vehicle. Rotor 20 may be a one-piece cast structure or a composite structure with a suitable composition. To the extent described herein, rotor 20 has a conventional construction. In operation, the rotor 20 is suitably mounted on a vehicle and the axially opposed surfaces of the friction rings 22,24 are selectively engaged by friction pads on one or more caliper devices (not shown). The system is designed to slow down or brake the associated vehicle wheels. The present invention provides the ventilation fin 26 length and/or
Alternatively, the space between these fins is selectively controlled to suppress vibration harmonic resonance, thereby promoting vibration damping during the braking operation described above. Suppressed like this! In harmonic resonance, the vibrational energy 1 is dissipated as "white noise," which is substantially imperceptible to the occupants of the vehicle.

Overall, in one important form of the invention, for frequency tuning of vibrational harmonics, a total number of fin cycles are selected, each cycle of which is associated with a fin 26 and its next neighbor in the row. and the space between the fins. The circumferentially aligned fin cycles are then divided into a plurality of nominally unequal partial angular segments. The nominal part size of the angular segment and the fin cycle in each segment are:
No. 4 issued to Gutdeyer Tire and Rubber Company, the parent company of the assignee of this application.
It has been determined that the techniques disclosed and claimed in Lauder No. 327,792 are modified to apply to brake rotors in accordance with the principles of the present invention. The disclosures of the aforementioned patent specifications are cited herein. It is preferable. The order of the partial angular segments in the circumferential fin rows is determined according to Section 3 of this invention.
In the embodiment of Figures 6 and 7, the sizes are placed in an irregular order or in an order of increasing segment size (Figures 4 and 5). - the angular dimensions and order of the fin cycles in each segment are
and 4 has a periodic pattern within each segment such that the wavelength of the predominant vibrational frequency for each segment corresponds substantially to the circumferential length of that segment. or in an increasing pattern that is non-periodic and non-repetitive within each segment (Figures 5.6 and 7). This nominally unequal segmentation of the ventilation fins, and the selected spacing between the fins, is such that the vibration frequency is tuned to suppress harmonic resonance.

In a second important form of the invention disclosed herein, the radial length of the ventilation fins is configured to adjust and damp the amplitude of vibrations and to balance the rotor about its axis of rotation. selected and controlled. This point locates the center of gravity of the rotor of a particular design, assuming that all fins have equal length, and then shortens the fin length as an exponential function of angle at alternate fin positions throughout the row. This is achieved by

In particular, to provide a ventilated disc brake rotor according to the principles of the invention, the number of cooling fins;
The critical angular spacing between the fins is usually subject to requirements due to mechanical strength and manufacturability. That is, the desired number of fins and the maximum possible spacing between the fins are selected such that the overall structure has the desired strength and stiffness under worst-case stress and temperature conditions. In one important feature of the preferred embodiment of the invention (Figures 3-7):
The number of fins is chosen to be a prime number. 3rd to 6th
In the illustrated embodiment, 23 fins are illustrated.

In the embodiment of FIG. 7, 29 fins are utilized. The example of FIGS. 3 to 7 (and FIG. 10) is
It is particularly applied to disc brake rotors for passenger cars with a diameter of 220 mm OD (outer diameter). The minimum spacing between fins is typically subject to manufacturability requirements. Measured circumferentially, the maximum space is 44.45 cranes (1,75 in,), and 6.35 to 12.7 m (0,2
A minimum spacing of 5 to 0.5 in.) has been found to be suitable for passenger vehicle applications.

The next step in providing the preferred embodiment of the invention (Figures 3-7) is to divide the circumferential dimension of the fin row into partial segments. A preferred technique of the invention utilizes selectable prime numbers. It is believed that the use of such prime numbers facilitates the frequency adjustment of the present invention. Therefore, the number of segments is
In the embodiments shown in Figures 7 to 7, a prime number, ie, 5, is preferred. Similarly, the nominal fraction associated with each segment is chosen such that its denominator is a prime number. Therefore, in Figures 3-7, the partial angular direction segments are nominally 18%/7+'/11%/Iff and! It consists of segments of . The sum of the segment parts is 0.
57, which is substantially less than 1.

The number of fin cycles in each segment is then determined as a function of the total number of fin cycles multiplied by the ratio of the nominal part number for each segment to the sum of all segment parts. Therefore, the number of cycles in the r'/S J segment in FIG.
is a function of the total number of fins (23) multiplied by the ratio of (to true).

In particular, for the embodiments of Figures 3-6, the selection of the number of fin cycles in each sub-segment proceeds as shown in the table below.

'/s 17017. 35 8
．． 05 8'/? 12155
．． 25 5.75 6wa...
7735. 16 3.68
4wa, 3 6545
．． 14 3.22 31Δ1
Ward μs, 10 2.3
Also, first, the "multiplication base" is found by multiplying the denominators of the nominal segment sizes. This radix is 85085 in our example. The nominal segment sizes (χ in column 1) are then each multiplied by the base (85085) and the result is
columns to arrive at a common fractional base. The number in the second column (Y) is then divided by the fractional base,
The adjusted fraction or decimal (Z) in the third column associated with each segment is arrived at. This adjusted segment fraction is multiplied by the selected total number of fin cycles (23), which is rounded to
cycle” number is reached.

For the embodiment of FIG. 7, the final steps of the above procedure are slightly modified as shown in the table below.

'/s, 35 10.2
11'/l, 25
7.3 7'/, , , 16
4.6 5wa+z
, 14 3.9 3
W, t, t02.9 Main, i.e., the number of fin cycles per segment is rounded to the nearest prime number in the embodiment of FIG. 7, rather than the nearest number in the embodiment of FIGS. . Note that this results in an extra cycle in the nominal segment to 18, and a deficit cycle in the 18 nominal segment. Additionally, this design decision
In keeping with the overall importance of the preferred form of this invention, possible prime numbers are utilized.

The next step in providing the preferred embodiment of the invention (Figures 3-7) is to determine the order of the subsegments in the fin row.

In the embodiments of Figures 3.6 and 7, the segments are arranged in an irregular size order, i.e. 18+'/171 clockwise in Figures 3.6 and 7.
They are arranged in the order '/ll+Iris j+'/7. In the embodiment of FIGS. 4 and 5, the order in which the sizes of the segments decrease, i.e. to 1+'/7%/11%/l
:l+'8.

The size and order of the fin cycles within each segment must then be determined. In all preferred embodiments of the invention, all fins 26 have equal angular dimensions. Therefore, the size of the fin cycle is the fin of one fin cycle,
This is then varied by varying the size or angular dimension of the space between the fins of adjacent fin cycles. Generally, the size and order of the fin cycles in the embodiments of FIGS. 3-7 are chosen as predetermined intersections of angles within each segment.

In particular, in the embodiments of Figures 3 and 4, the size and order of the fin cycles within each segment is such that the predominant vibration frequency for that segment corresponds substantially to the circumferential length of that segment. It is determined that

This point is shown in the table below:
l 6 AABCCB1mu,
4 ABCB 1mu3 3 ABC'/, -12
The AC dimension rA J is the minimum spacing between the fins, or 0.5 in, in the embodiment under discussion. Dimension rCJ is the maximum spacing between fins or 1,75 in. in the embodiment under discussion. The dimension rB J is in this example half of rA J and rCJ, or 28.57511 (1,125
in, ).

In the embodiment of FIGS. 5-7, the fin cycles within each segment are arranged in length order, with successive interfin spacings being substantially uniform increments between maximum and minimum design limits. is increasing. In particular, the first mutual interfin spacing in each segment of this example is
The minimum design size (44,45 m or 5,1/7, 1/11, 1
/13 and 1/1775in,). The intermediate spaces are then sized to increase uniformly from the smallest to the largest. For example, the mutual interfin spacing in the embodiments of FIGS. 5 and 6 is given by the table below: '/? 12.70('/
Note that it is not always possible to make the last space equal to the maximum dimension using simple fractional increments. The spacing dimensions and order within each segment in the FIG. 7 embodiment are determined in a similar manner.

In a second important aspect of the invention, the balance of the rotor about its axis of rotation is obtained, and the amplitude adjustment (damping) of the vibrational harmonics changes the length of the alternating fins, i.e. every other fin. This is achieved by varying it as a function of the angle around the column. In particular, the radial dimension or length of the alternating fins is shorter than the length of the intermediate fins (which are of equal length) as an exponential function of the angle around the fin row;
Or it has been reduced. The procedure utilized is described in detail in connection with the embodiment of FIG. 7, and the embodiments of FIGS. 3-6 are designed in a similar manner (as in the embodiment of FIG. similar).

FIG. 9 shows the fins 8-0 in the embodiment of FIG. 7 distributed around a circle 40, which circle is located at a radius r from the rotor axis χ, which corresponds to the radius of the center of gravity of the fin. be. Once the positions and spacings of the plurality of fins are determined according to the foregoing discussion, the center of gravity CG and the imbalance position and amount associated with the center of gravity CG are determined either analytically or empirically. A straight line passing through CG and ing.

FIG. 8 graphically illustrates the amount of material that must be "removed" from alternating fins A-0 in order to balance the rotor and at the same time provide the desired amplitude adjustment described above. In FIG. 8, the abscissa represents the angle around the circle 40, according to which the relative position of the fin A-0 is placed. The ordinate in FIG. 8 represents the amount by which each fin is to be shortened compared to the intermediate fins, which all have the same length. Point C adjacent to fin J in Figure 9
In Fig. 8, the angle of G/rl-rz is the shortest fin,
That is, it is placed at a position corresponding to an angle of 120° from the fin 8.

In this form of the invention, then alternating fins A
The length of -0 is determined as a function of the exponential equation y=ax' of FIG. 8, where y is the fin length, X is the radian angle, and b is a constant. As a starting point, b is made equal to 1. However, in implementing this invention, since the number of fins is limited, it is necessary to change the constant value from 1 upward or downward.

In one example of the invention according to the embodiment of FIG. 7, the nominal fin length is 3.66 cm (1,44 in,) and the length of the alternating fins A-0 is given by the table below: m-y- Fin length: tm (in,)A
20.83 (0,82)8 23
．． 11 (0,91) C25,15 (0,99) D 27.69 (1,09) E
28.45 (1,12)F
24.03 (1,17)G
30.73 (1,21)++
30.99 (1,22)I”
30.73 (1,21)J
35, 1/7, 1/11, 1/13 and 1/1775 (1,25)”
35, 1/7, 1/11, 1/13 and 1/17
50 (1,24) bi 30.99
(1,22) "35, 1/7, 1/11, 1/13 and 1/1750 (1,24)N
32.51 (1,28)0
34.04 (1,34) Note that fins marked with an asterisk are not ordered by length. Due to the limited number of fins, the methods described above can sometimes only provide an approximate balance. The length of the individual fins is then selectively varied to balance the rotor while maintaining a substantially exponential length function as described above. Also, since an odd number of fins are used, adjacent fins A and 0 are shortened.

FIG. 10 shows a ventilation fin pattern according to another embodiment of the invention.

In the example of FIG. 10, the design begins with a uniformly spaced row of fin positions, in this case there are 28 positions A-BB. The fins are then deleted or removed from their positions in increasing spaces around the row.

That is, one fin at position B separates "empty" positions A and C, two fins at positions and E separate "empty" positions C and F, and so on.・・・
.... By arranging the empty fin positions in a staggered manner, emphasis on vibrational harmonics is suppressed. In order to achieve amplitude adjustment and balance the rotor, the fins in alternating positions are changed in angle as shown in FIG. shortened as an exponential function (F, J,
It can be seen that there are no fins to be shortened at 0 and U. ). The fins in the embodiment of FIG. 10 have equal angular dimensions.

A ventilated disc brake rotor having the configuration of FIG. 10 was constructed and compared with respect to vibration damping with a disc brake rotor of conventional construction and the same size and composition. The conventional rotor used for comparison is the one used in Freisler cars and is equipped with 28 fins that are equally spaced and have the same angular dimensions. The radial dimensions of the fins are alternately long and short along the row, with all long fins having equal lengths and all short fins having equal lengths. The damping coefficient is 0.25~0.2
9, while the damping coefficient for the embodiment of FIG. 10 is 0.60.
Met.

Accordingly, a first important aspect of the invention, as disclosed in connection with FIGS. 3-7, contemplates a method of manufacturing a brake rotor in which a circumferential array of cooling fins is , is divided into multiple unequal nominal subsegments.

Preferably, the number of fins, the number of segments and the nominal segment fraction are prime numbers. The actual size of each sub-segment of ゛ for the number of inter-fin spaces placed here is then determined as a function of the ratio of the fractional segment to the numerical sum of all segment fractions, and the nearest neighbor number (third to (Figure 6) or rounded to the nearest prime number (Figure 7). Due to the limited number of fins and inter-fin spacing across the rows, the nominal sub-segments i.e. 1/5, 1/7, 1/11, 1/13 and 1/17 and to are not equal, but by applying the latter technique to the embodiment of FIG. 7, the subsegments in the actual column are made equal. The order of the partial segments is either not arranged in size order (Figs. 3, 6 and 7) or arranged in decreasing size order (Figs. 4 and 5). The size and order of the spaces within each row of segments have a substantially regular pattern, the pattern wavelength being substantially equivalent to the circumferential length of the associated segment.
), or the size and order have a pattern of increasing successively between the design minimum and maximum values (Fig.
~Figure 7).

The second aspect of the invention, which is preferably utilized in combination with the first embodiment as described in detail in connection with FIGS. 7-9, but which may also be utilized separately with respect to FIGS. In the configuration, the length of the fins at alternate fin positions is varied as an exponential function of the angle along the row.

In a third form of the invention, described in connection with FIG. It has been selectively deleted at this position.

In a third form of the invention, where the interfin spacing is in a pseudo-chaotic position and/or pseudo-chaotic dimension, as a function of the angle along the zero line, frequency-adjusted damping or suppression of the vibrational harmonics of the rotor is achieved. Selective shortening of the fins in alternating fin positions achieves amplitude adjustment of the vibrational harmonics and is also utilized for rotor balancing.

Although the invention has been described in detail in relation to ventilated disc brake rotors, it is clear that the principles of the invention are equally applicable to the manufacture of drum brake rotors, i.e. brake drums, in which case the circumference of the drum The spacing between the cooling fins and/or their axial length is varied in this invention to reduce brake squeal.

[Brief explanation of drawings]

FIG. 1 is an axial elevational view of a ventilated disc brake rotor, FIG. 2 is a sectional view taken along line 2-2 in FIG. 1, and FIGS. 3 to 7 show five preferred embodiments of the present invention. A schematic diagram of a circumferential pattern of a disc ventilation fin according to an embodiment, FIGS. 8 and 9 are graphs useful for understanding one embodiment of the present invention, and FIG. 10 is another disc brake fin of the present invention. A schematic diagram of the pattern, FIG. 11, is a graph useful in explaining the structure of FIG. 20・・・・・・・・・Brake rotor 22.2
4...Brake surface

Claims (1)

[Claims] 1. A method of manufacturing a brake rotor including at least one braking surface and a circumferential row of cooling fins, comprising: (a) selecting the total number of fin cycles in the row; and each fin cycle comprises one fin and the space between this fin and the next adjacent fin in the row;
(b) dividing said column into a plurality of unequal nominal partial angular segments; and (c) distributing said nominal partial angular segments along said column in a predetermined order. (d) in each said segment, selecting a number of fin cycles as a function of said total number of fin cycles multiplied by the ratio of said corresponding nominal sub-segment to the numerical sum of said nominal sub-segments; and (e) selecting an angular dimension of each fin cycle in each of the segments as a predetermined function of the order of the fin cycles in the corresponding segment. 2. The manufacturing method according to claim 1, wherein the total number of fin cycles selected in the step (a) is a prime number. 3. The manufacturing method according to claim 2, wherein the total number is 23. 4. The manufacturing method according to claim 2, wherein the total number is 29. 5. The manufacturing method according to claim 2, wherein the number of segments into which the column is divided in step (b) is a prime number. 6. Claim 5, wherein the number of segments is 5.
The manufacturing method described in section. 7. The method of claim 2, wherein the nominal portion size of each said nominal partial angular segment is a prime number. 8. The nominal portion size is 1/5, 1/7, 1/1
1, 1/13 and 1/17, the manufacturing method according to claim 7. 9. The manufacturing method according to claim 1, wherein said step (c) comprises arranging said segments in order of size along said rows. 10. step (c) comprises arranging the segments along the column in an order other than size order;
A manufacturing method according to claim 1. 11. The manufacturing method according to claim 1, wherein the total number of fin cycles in each segment selected in step (d) is a prime number. 12. Step (e) comprises arranging the fin cycles in each segment by length, such that the wavelength of the predominant vibrational frequency of each segment substantially corresponds to the circumferential length of the segment. The manufacturing method according to claim 1, wherein 13. said step (e) comprises: (e1) selecting a predetermined number of different fin cycle lengths equal to predetermined maximum and minimum cycle lengths and at least one cycle length between said maximum and minimum cycle lengths; e2) The cycle length is
arranging in each said segment substantially in cycle order, such that the order completes one cycle within each said order.
The manufacturing method according to item 2. 14. The method of claim 1, wherein step (e) comprises arranging the fin cycles in the segments in order of length. 15. said step (e) comprises: (e1) selecting maximum and minimum lengths for said fin cycle; and (e2) determining a cycle length in each said segment substantially between said maximum and minimum lengths; 15. A manufacturing method according to claim 14, comprising varying in uniform increments. 16. The method of claim 1, wherein all said fins have equal angular dimensions. 17. The method of claim 16, comprising the step of: (f) varying the radial length of selected ones of the fins and causing the remainder of the fins to be of equal length. 18. The method of claim 17, wherein step (f) comprises varying the radial length of alternating ones of the fins. 19. The method of claim 18, wherein step (f) comprises varying the radial length of alternating ones of the fins as a function of angle along the row. 20. The method of claim 19, wherein step (f) comprises varying the radial length of alternating ones of the fins substantially as an exponential function of the angle along the row. Production method. 21. an annular braking surface arrangement engaged with a braking element and a plurality of fins arranged in a circumferential row and coupled to the braking surface arrangement for heat dissipation;
A method for suppressing harmonic vibration by frequency adjustment in a brake rotor comprising: (a) selecting the total number of fins in said row to be equal to a prime number, and each said fin having equal angular dimensions; (b) divide said column into nominal partial angular segments of prime numbers, and (c) calculate the number of mutual interfin spaces in each said segment relative to the numerical sum of all nominal partial fractions of the segment. , as a function of the ratio of the corresponding nominal partial fractions, and (d) selecting the angular dimension of the interfin space in each said segment as a predetermined function of the angle in each said segment. Method. 22. The method of claim 21, wherein the number of mutual interfin spaces selected in step (c) is a prime number. 23. suppressing harmonic vibrations of said rotor by amplitude adjustment and at the same time balancing said rotor about its axis of rotation; (e) adjusting the radial length of alternating ones of said fins substantially in said row; 22. The method of claim 21, comprising varying the angle along the fins as an exponential function and achieving this by making the remainder of the fins all of equal length. 24. A method for adjusting the frequency of harmonic vibration in a method for manufacturing a brake rotor comprising a braking surface and a circumferential row of cooling fins, the method comprising: (a) arranging a plurality of fin positions equally spaced along the row; and (b) positioning the cooling fins at the selected first positions of the positions, and removing the fins from the selected second positions of the positions; The number of fin positions between positions is increased step by step along the row. 25. (a) varying the radial length of the fins at alternating positions of the fin positions along the row;
25. The method of claim 24, wherein the amplitude of the harmonic vibrations is adjusted by making the remainder of the fins of equal length. 26. Claim 25, wherein step (c) comprises varying the radial length of the fins at the alternating positions substantially as an exponential function of the angle along the row. the method of. 27, an annular braking surface device engaged with the braking element, arranged in a circumferential row at predetermined angularly spaced locations and coupled to said braking surface device for heat dissipation; A method for suppressing harmonic vibration in a brake rotor including a plurality of fins, the method comprising: (a) selectively controlling the radial length of the fins at alternating positions of the fins along the row; A method comprising the step of substantially increasing the length as a predetermined function of angle. 28. The method of claim 27, wherein the predetermined function is a substantially linear function. 29, (b) selecting the total number of fins in said row to be a prime number, with each said fin having equal angular dimensions; and (c) defining said row as unequal nominal partial angular segments of prime numbers. (d) the mutual inter-fin space in each segment,
(e) the angular dimension of the interfin space in each said segment is selected as a function of the ratio of the nominal partial fraction of the corresponding segment to the numerical sum of all nominal partial fractions of the segment; 29. The method of claim 28, comprising: selecting as a predetermined function of the angle in each segment. 30, (b) defining a plurality of equally spaced fin positions along said row; and (c) locating said cooling fin at a selected first position of said positions; 29. The method of claim 28, further comprising the step of removing said fins from two positions and causing the number of fin positions between said second positions in said positions to increase step by step along said row. . 31, comprising an annular braking surface arrangement and a circumferential row of cooling fins coupled to the braking surface arrangement for heat dissipation, the row of fins comprising a selected number of fin cycles; the fin cycle is defined by one fin and the space between the next adjacent fin in the row and the one fin;
The fin cycles are grouped into a plurality of nominal partial angular segments such that the number of fin cycles in each segment is the nominal partial fraction of the corresponding segment relative to the numerical sum of all nominal partial fractions of the segment. A brake rotor comprising a predetermined function of a ratio of partial fractions, and wherein the angular dimension of each fin cycle in each said segment is a predetermined function of the angle in the corresponding said segment. 32. The rotor according to claim 31, wherein the total number of fins is a prime number. 33. The rotor of claim 31, wherein said total number is twenty-three. 34. The rotor of claim 31, wherein said total number is twenty-nine. 35. The rotor according to claim 31, wherein the number of segments into which the row is divided is a prime number. 36. The rotor of claim 31, wherein the number of segments is five. 37. Claim 31, wherein the nominal partial fraction size of each nominal partial angular direction segment is a prime number.
The rotor described in Section. 38. The rotor of claim 37, comprising a disc brake rotor having a pair of axially spaced annular braking surface devices separated by the fins and coupled together. 39, the nominal partial fractions are 1/5, 1/7, 1/1
39. A rotor according to claim 38, consisting of 1, 1/13 and 1/17. 40. The rotor of claim 31, wherein the segments are arranged in order of size along the rows. 41. The rotor of claim 31, wherein the total number of fin cycles in each segment is a prime number. 42. The fin cycles are arranged lengthwise in each of the segments such that the wavelength of the predominant vibrational frequency of each segment substantially corresponds to the circumferential length of the segment. The rotor according to range 31. 43. Claim 43, wherein said fin cycles are arranged in a substantially periodic order within each said segment, said periodic order completing one cycle within said length of said segment. The rotor according to item 42. 44. The rotor of claim 31, wherein the fin cycles are arranged lengthwise in each of the segments. 45. The rotor of claim 44, wherein the fin cycles in each of the segments are arranged in length order with substantially uniform increments between predetermined minimum and maximum lengths. . 46. The rotor of claim 31, wherein all said fins have equal angular dimensions. 47. The radial length of alternating ones of said fins is varied as a predetermined function of the angle along said row, and the remaining ones of said fins have equal lengths. The rotor described in Section. 48. The rotor according to claim 47, wherein the predetermined function is an exponential function. 49. A brake rotor comprising an annular braking surface arrangement and a plurality of cooling fins disposed at selected fin locations in a circumferential row about the rotor and coupled to the annular braking surface arrangement for heat dissipation, In order to damp harmonic oscillations thereof, the cooling fins at alternating positions of the fin positions have radii that decrease substantially as an exponential function of the angle along the row compared to the remaining fins having equal lengths. A brake rotor having a directional dimension. 50, wherein the fin locations are uniformly spaced along the row and separated from each other by increasing spacing increments along the row; 50. The rotor of claim 49, deleted. 51, said row of fins comprising a predetermined number of fin cycles, each fin cycle comprising one fin and a space formed between said one fin and the next adjacent fin in said row; limited, said fin cycles are grouped into a plurality of nominal partial angular segments, and the number of fin cycles in each said segment corresponds to the numerical sum of all nominal partial fractions of the segment. claim 49, wherein the angular dimension of each fin cycle within each said segment is a predetermined function of the angle in said corresponding segment Rotor listed.