DE2812852A1 - PLATE FOR FRICTIONAL CONTACT - Google Patents

Description

PATENT Attorney DIPL-ING. 8000 MÜNCHEühäa ^ λλγ

KARLH. WAGNER - ■ _ Gewürzmühl4f $ s $ e4 "^

PO Box 246

77-S-2991

CATERPILLAR TRACTOR CO. , Peoria, 111.61629, V.St.A.

Frictional contact plate

The invention relates to frictional engagement or friction contact members, such as brakes and clutches. In particular, the invention relates to disk-shaped Plates that are useful for brakes and clutches, with an elastomeric material on one side of the Disc is deposited in a pattern that allows for the application of fluid to the elastomeric material covered pane side permitted.

Methods and apparatus using frictional contact or the frictional engagement are already known, wherein one side of a metal disc is brought into frictional contact with a generally flat reaction member, and wherein an elastomeric material is attached to the side of the disc and in the form of a plurality of ascending arcuate shapes Web is formed which are generally concentric with the disc, with the adjacent webs through a plurality of corresponding arcuate grooves are separated. In such methods and devices, the touch by contacting the reaction member and the elastomeric material Caused covered side of the disc, while a flow center of the side covered with elastomeric material is fed to the disc.

809842/0646

TELEPHONE: (089) 298527 TELEGRAM: PATLAW MÖNCHEN TELEX: 5-22039 patw d

ORIGINAL INSPECTED

In achieving frictional contact or frictional engagement a problem has arisen with the known methods and the known devices. This problem persists in that the webs made of elastomeric material showed a tendency to tear along their length. Such a problem is natural of an extraordinarily serious nature in that it leads to failure. from clutches and brakes using such disks can. Furthermore, such disks are used in a number of conditions where they have different levels of stress are exposed. It would be desirable to provide discs for these various conditions or requirements which one could accurately predict that the webs would not tear.

Summary of the invention. The invention aims to overcome one or more of the problems mentioned. According to the invention a plate is provided for frictional engagement with a generally flat reaction member, wherein a metal disc attached to one side carries an elastomeric material, which is available in a variety of upright, arcuate webs are formed which are generally concentric with the disc, and further wherein a plurality Corresponding arcuate grooves separates the adjacent webs. A ratio R from the width of a corresponding web the sum of the width of the corresponding web plus the width of a corresponding groove is given by an equation as follows Are defined:

0.80> R> 0.755 - 1o5i

P + Kd

where P = a pressure in psi applied to the elastomer material to bring the covered side of the disc into contact or engagement with the reaction member, d = a change in thickness of the generally flat reaction member, expressed in inches, K = a spring rate in psi (pounds per square inch) per inch of elastomeric material and S = the elastomeric stress limit, expressed as a decimal size of the elastomeric material.

809842/0646

According to a further aspect, the invention provides a device for the frictional engagement of a covered with elastomeric material Side of a metal disc of the type just described with a substantially flat reaction member before. The device has, in addition to the aforementioned plate, means to the reaction member and the elastomeric material-covered side of the To bring the disc into frictional engagement, further means being provided are to supply a fluid to the disc side coated with elastomeric material. According to another aspect According to the invention, a method is provided to reduce the initiation of cracks or fractures in the aforementioned elastomeric material. The improved method provides for the shaping of the elastomeric material in such a manner that the above mentioned limitation the ratio R is satisfied.

Further advantages, objectives and details of the invention emerge in particular from the claims and from the description of embodiments based on the drawing; in the drawing shows:

Fig. 1 is a plan view of a frictional engagement plate formed in accordance with the invention;

Fig. 2 shows a device for the frictional engagement of a Disc according to FIG. 1 with a substantially flat reaction member, partially as a partial side view and partly schematically;

Fig. 3 webs of the plate for the frictional engagement according to of the invention in cross section;

Fig. 4 graphically shows a determination of the elastomer load or stress limit of the implementation of the invention useful elastomeric material.

Fig. 1 shows a disc 10 made of a metal such as Steel or the like., Is and in the middle has a plurality of teeth 12 for engagement with a drive member.

809842 / 064i

An elastomeric material 14 is attached to one side 16 of the disc. The elastomeric material 14 is available in a variety of formed upstanding, arcuate webs 18 which are arranged concentrically with the disk 10 as a whole, wherein a A plurality of corresponding arcuate grooves 20 separates the adjacent webs 18.

In operation, the disc 10 is in contact or engagement with a reaction member 22 by virtue of the disc 10 is urged toward reaction member 22 using a motor shown schematically at 24 driven by a pump 26 Or the like. Can be driven. The pump 26 can also provide a fluid via a line 28 and a passage 30 to with elastomeric material covered side 16 of the disk 10 and in particular to the grooves 20 and webs 18 deliver. The engine 24 thus serves to the webs 18 in frictional engagement with the Reaction member 22 to press.

It has been found that a serious problem arises in the use of the apparatus described. In short, there is this problem is that the webs 18 tear along their length as they frictionally engage the reaction member 22 or break. The present invention particularly relates to the physical relationship between the widths of the webs 18 and the grooves 20, i.e. the relationship necessary to ensure that breakage or tearing does not occur. Fig. 3 shows a pair of webs with an interposed groove 20. It has now been found that between the Width of a web 18 and the sum of the width of the web 18 and the next adjacent groove 20 is a critical relationship consists. If one considers the difference between a first side 32 of a groove 18 and a first side 32 'of the next adjacent Web referred to as the length between adjacent webs, the ratio of the width of the web 18 to the length between adjacent webs, hereinafter referred to as the web-to-length ratio is critical in preventing the initiation of fracture within each of the webs 18.

809842/0646

- 28 Ί 2852

The initiation of the break within the webs 18 is not easy Phenomenon, it is determined to be dependent on several factors. First, it turned out that the The initiation of the fracture or the beginning of the fracture depends on the nominal pressure with which the disk 10 against the reaction member 22 is pressed. Second, it was determined that the initiation of the break or the start of the break was dependent on the speed of rotation of the disk 10 depends on their contact with the reaction member 22, which in turn determines the temperature to which the Elastomer material 14 is lifted by the frictional contact with the reaction member 22. Third, it turned out that the fraction of the spring constant of the specie ^ en used Elastomer material 14 depends. Fourth, it depends The initiation of fracture depends on the degree of smoothness of the reaction iron 22 where it touches the webs 18. The overall relationship is proportionate complicated and if one calculates a load profile within a web 18, one would create a shape diagram of the type generally shown in FIG. 3, in which the maximum or peak load is in the regional insect kingdom 34 would occur. Further, if a disc 10 with an elastomeric material 14 provided thereon, as in FIG shown, is used attached to a reaction member 22, so it is necessary to use a hydraulic fluid such as Oil or the like. To have on the webs 18, since the great majority (generally over 90%) of the clutch or braking force between the webs 18 and the reaction member 22 is absorbed in a shear stress of the intermediate oil layer. There is thus an upper limit on the web-to-length ratio exerted, since when this upper limit is exceeded, oil is not properly applied to the webs 18 can be applied, which has the result that the frictional engagement between the webs 18 and the reaction member 22 is not the necessary frictional force due to the shear effect on the balance provides.

In short, the inventive knowledge lies in the fact that then, if one defines the web-to-length ratio as R, the The following relationship must exist:

809842/0646

0.80 ^ R ^ 0.755-1051 (S / (P + kd)).

In the above equation, P is a pressure, generally expressed in psi, applied to engage the elastomeric material covered sides of the disc with a reaction member. In other words, P is the nominal pressure applied between Washer and reaction member 22. A change in thickness of the generally flat reaction member 22 is d and is normally shown in Expressed in inches. A spring constant of the elastomeric material is represented by k and is generally expressed in psi per Expressed in inches. S is equal to the elastomer load limit, expressed as one decimal of the elastomer material. the Elastomeric stress limit of the material 14 is determined by examining samples of the same, and the results of a Such studies of a specific material are shown in Fig., namely the study of a copolymer of Vinylidene fluoride and hexafluoropropylene, a material that sold by DuPont under the Viton trademark. This particular material also contained about 36 weight percent carbon black and about 40 weight percent glass fiber. A line 36 represents a number of test cycles that the elastomeric material 14 may be subjected to, which is shown in FIG Form of webs 18 and grooves 20 is formed and attached to a disc 10 before the break occurs. The elastomer stress limit is represented by a line 38 which indicates that so long the elastomeric stress limit is not is exceeded, then the elastomeric material 14 will not fail even after one million cycles in the fatigue test. Of the The fatigue test carried out used a vibrating load foot with variable force options to achieve a uniform Apply pressure to a representative sample of the molded friction material in an oil bath at the clutch operating temperature of nominally 250 F.

It has been found that the above relationship is particularly correct and particularly useful when P is in a range from about 100 psi to about 800 psi, and more preferably

809842/0646

? P1? FiS?

in a range of from about 250 psi to about 600 psi falls. It is also preferred that k fall within a range of from about 40 psi per inch to about 400 psi per inch, where even more preferred values of k range from about 60 psi per inch to about 120 psi per inch. In general, it is preferred that the reaction member 22 is substantially flat, and thus preferred values of d fall within a range of about 0.0001 inches to about 0.005 inches, and most preferably the values fall within a range of about 0.005 inches to about 0.004 inches. Preferably, an elastomer material 14 is chosen such that S falls in a range from about 0.05 to about 0.20, and preferably in a range from about 0.10 to about 0.1 Σ Accordingly, it is generally preferred that R be in the range of about 0.8 to about 0.3, with more preferred Values for R fall in a range from about 0.75 to about 0.45.

The elastomeric material 14 preferably comprises from about 20% to about 50% by weight elastomer, the Elastomer preferably a fluoroelastomer such as a copolymer of hexafluoropropylene and vinylidene fluoride is, but the elastomer can advantageously also be one of the following: polyacrylate, acrylonitrile, silicone, Fluorosilicone, chloroprene or urethanes and copolymers and Mixtures of these. The aforementioned elastomeric material also preferably comprises from about 12% to about 40% carbon black, and from about 20% to about 60% glass or ceramic asperite particles 40, and per 20% to 50% weight percent elastomer and generally uniformly distributed throughout the elastomer. The asperite particles 40 form hard particles in the relative soft elastomeric material 14, and it is believed that the edges of the asperite particles 40 the shear of the hydraulic Increase fluid supplied to the lands 18, which will give them better frictional characteristics be granted.

Modifications of the invention are given to those skilled in the art.

In summary, the invention thus provides a plate for frictional engagement with a generally flat reaction member

809842/0646

4t

before. The plate has a metal disc 10 with an elastomeric material 14 attached to it on one side 16, which formed in a plurality of upstanding, arcuate ridges 18 generally concentric with the disc with a plurality of corresponding arcuate grooves 20 separating adjacent lands. A ratio R out the width of a corresponding web to the sum of the width of the corresponding web plus the width of a respective corresponding groove (a corresponding length) is defined by an equation which is a function of the engagement of the Disc with the pressure applied to the reaction member, the change in thickness of the reaction member, the spring constant of the elastomer and the proportion of peak stress that is in the elastomer during engagement of the disk with the reaction member compared to the minimum stress at which the failure of the elastomer material begins.

809842/0646

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Claims (22)

Claims 1 .J A plate for the frictional engagement with a generally flat reaction member, in which a metal disc is provided, on one side of which an elastomeric material is fixed, which is formed in a plurality of upright arcuate ridges generally concentric with the disc, and wherein a plurality of corresponding arcuate grooves separates adjacent webs, characterized in that a ratio R of the width of a corresponding web (18) to the sum of the width of the corresponding web (18) plus the width of the corresponding groove is defined by the following equation: 0.80 Λ R ^ 0.755 - 1051 (S / (P + kd)), where P = a pressure in psi, applied for the engagement of the side of the disk with the reaction element covered with elastomer material, d = a variation in thickness of the generally flat reaction member, expressed in inches; k = a spring rate constant in psi per inch of the elastomeric material and S = the elastomer stress limit, expressed as one decimal of the elastomer material. 2. The plate of claim 1, characterized in that P is in a range from about 100 psi to about 800 psi is that k falls within a range of from about 40 psi per inch to about 400 psi per inch that d falls within a range of falls about 0.0001 inch to about 0.005 inch that S in falls within a range from about 0.005 to about 0.20 and that R finally falls within a range from about 0.8 to about 0.3 falls. 809842/0646 3. Plate according to claim 1, characterized in that P in a range from about 250 psi to about 600 psi falls that k falls within a range of about 60 psi per inch to about 120 psi per inch that d falls within a range of falls about 0.0005 inches to about 0.004 inches, that S falls within a range of about 0.10 to about 0.18 and that finally R falls in a range from about 0.75 to about 0.45. 4. Plate according to one or more of the preceding claims, in particular according to claim 1, characterized in that the elastomer material has the following: Approximately 20 weight percent to about 50 weight percent elastomer, from about 12 to about 40 weight percent carbon black, and from about 20% to about 60% by weight glass or ceramic asperite particles generally uniformly distributed throughout the elastomer. 5. Plate according to one or more of the preceding "claims, in particular according to claim 4, characterized in that that the elastomer is selected from the following group: fluoroelastomer, acrylonitrile, silicone, fluorosilicone, chloroprene and urethane, as well as copolymers and mixtures thereof. 6. Frictional engagement device characterized by the Features of claim 1 and by the following further features: means (24) for driving the reaction member (22) and the elastomeric coated side of the disc in frictional engagement, and means (26-30) for providing a fluid on the side of the disc covered with elastomer material. 7. The device according to claim 6, characterized by the features of the characterizing part of claim 2, 8. Apparatus according to claim 6, characterized by the features of the characterizing part of claim 3. 809842/0646 9. Apparatus according to claim 6, characterized by the features of the characterizing part of claim 4. 10. The device according to claim 9, characterized by the features of the characterizing part of claim 5. 11. Process to reduce the initiation of fracture in one elastic material in frictional engagement of one side of a metal disc with a generally flat reaction member, wherein the .elastomer material is attached to the mentioned side of the disc and in a variety of upright, arcuate webs (18) is formed concentrically as a whole with the disc, and wherein further a plurality of corresponding arcuate grooves separate the adjacent webs and the engagement is brought about by the reaction member against the elastomer-covered side of the disc is pressed while a fluid is supplied to the elastomer-covered side of the disc, characterized in that that the elastomer material is shaped in such a way that a ratio R is derived from the width of a corresponding web to the sum of the corresponding width of the web plus the width of a respective corresponding groove is defined by the following equation: 0.80> R Λ 0.755-1051 (S / (P + kd)), where: P = a pressure in psi, applied for the intervention the elastomer-coated side of the disk with the reaction element, d = a variation in thickness of the generally flat reaction member, expressed in inches; k = a spring rate constant in.psi per inch of the elastomeric material and S = the elastomer stress limit, expressed as one decimal of the elastomer material. 8098A2 / 06A6 12. The method according to claim 11, characterized by Features of the characterizing part of claim 2. 13. The method according to claim 11, characterized by the Features of the characterizing part of claim 3. • 14. Method according to claim 13, characterized by the features of the characterizing part of claim 4. 15. Process for reducing the initiation of cracks in elastomeric material in frictional engagement of one side of a metal disc with a generally flat reaction member, the Elastomeric material is attached to the mentioned side of the disc and in a variety of upright, arch-shaped Web is formed which are generally concentric with the disc, and wherein a plurality of corresponding arcuate grooves separating the adjacent webs and the engagement is brought about by the fact that the reaction member against the elastomeric material-covered side of the disc presses while a fluid is supplied to the disc side coated with elastomer material, characterized in that, that one has a ratio R from the width of a corresponding web to the sum of the width of the corresponding Ridge plus the width of a respective corresponding groove limited sufficiently low, so that the fluid Web can be supplied to take up over 90% of the force between the webs and the reaction member, and one demands that the ratio R is sufficiently high so that the initiation of the break approximately 100,000 cycles of intervention is initiated, namely under the construction conditions of use. 16. The method according to claim 15, characterized in that 0.8 j> R> 0.30. 809842/0646 17. The method according to claim 15, characterized in that 0.75> R> 0.45. 18. Frictional engagement device, particularly after one or more of the preceding claims, characterized by 1) a metal disc, 2) a generally flat reaction link for engaging one side of the disc, 3) an elastomeric material attached to the mentioned side of the disc, the elastomeric material being available in a variety of is formed upright, arcuate webs which are generally concentric to the disc, and further a plurality of corresponding arcuate grooves separating the adjacent lands, and where a ratio R of the Width of a corresponding ridge to the sum of the width of the corresponding ridge plus the width of a respective corresponding one Groove is limited to lie sufficiently low so that fluid can take up over 90% of the webs the force engagement between the webs and reaction member delivered can be, and the limitation is sufficiently high so that the fracture or crack initiation within the land does not occur for at least approximately 100,000 engagement cycles under design conditions. 19. The device according to claim 18, characterized by 0.80 ^ R ^ 0.30. 20. The device according to claim * 18, characterized by 0.78 i Ri 0.45, 21. A plate for frictional engagement with a generally flat reaction member, particularly after one or more of the preceding claims, characterized by a metal disc and one attached to one side of said disc Elastomer material, which is formed in a plurality of upright, arc-shaped webs that are concentric on the whole extend with the disc, and furthermore a 809842/0646 There is a plurality of corresponding arcuate grooves separating the adjacent lands, and there is a ratio R from the width of a corresponding ridge to the sum of the width of the corresponding ridge plus the width of a respective one corresponding groove is within a range of about 0.80 to about 0.30. 22. Plate according to claim 21, characterized by 0.75> R> 0.45. 809842/064