Friction clutch - dynamic brake with dissipation of the heat generated by friction directly from the friction surfaces

Abstract

This invention removes the limitations of friction clutches both in terms of duration and frequency of harmless slipping under load. The above was achieved with an original design enabling efficient removal of the heat generated by friction directly from the friction surfaces. The removal of limitations, as achieved by this invention, opened up the possibility of the friction clutch also having a dynamic braking function and a fail-safe clutch function. The invention is not limited in terms of dimensions, transferable torque, or dynamic braking torque, and the use of the invention would not be excluded from application in any industrial branch. The invention was inspired by the current state of the art in the construction of ship winches for maritime objects towing, and it could be regarded as having the potential to push the boundaries and change standards – at the very least in the winch-making industry.

Description

[0001] FRICTION CLUTCH - DYNAMIC BRAKE WITH DISSIPATION OF THE HEAT GENERATED BY FRICTION DIRECTLY FROM THE FRICTION SURFACES

[0002] DESCRIPTION

[0003] Field of invention

[0004] This invention pertains to the field of mechanical engineering, and more precisely to power and motion transmitters.

[0005] State of the art to be affected by the invention

[0006] In a significant part of industrial applications, the state-of-the-art transmission and / or limitation of the delivered torque is achieved by lamellar friction clutches, whose compactness is both an important advantage and a significant disadvantage. Due to the exceptional compactness of lamellar friction clutches, such clutches cannot be used in drives where long and / or frequent slippage is required, as most of the heat generated by friction would be retained in the compacted lamellae, which would cause extreme heat and irreparable damage to the clutch.

[0007] Technical problem

[0008] The technical problem pertaining to lamellar friction clutches stems from their inability to efficiently dissipate heat that is generated by the sliding of compacted lamellae under load, which results in a fast increase in temperature with rapid degradation of friction elements, including friction linings.

[0009] A technical problem solved by this invention is the efficient removal of the heat generated by friction directly from the friction surfaces, which ensures harmless sliding.

[0010] In addition to the above, another technical problem solved by this invention is the way a friction clutch can be used, beside as a clutch, both as a dynamic brake and as a fail-safe clutch.

[0011] This invention also solves the technical problem of controlling the friction torque. Presentation of the essence of the invention

[0012] This invention solves the problem of effectively dissipating the heat generated by friction directly from the friction surfaces where the heat is generated.

[0013] The said problem is solved with unique established proportions of the friction elements, with the surfaces of the friction pads, below which the friction occurs, being more than an order of magnitude smaller than the areas of the friction surfaces on the transmission elements.

[0014] Given such an arrangement, large zones on the transmission elements remain exposed to unobstructed heat dissipation by the cooling medium directly from the heated friction surfaces, as those areas are free from contact with the friction pads at that time.

[0015] With reference to the version of the invention in accordance with Fig. 1 and 2, the ratio of the sizes of surfaces the heat is dissipated from and the surfaces under the friction pads amounts to 20:1 .

[0016] The surface ratio of 20:1 does not constitute a fixed determinant of the invention.

[0017] Efficient removal of heat from the site of heat generation, as provided by the present invention, solves the problem related to prolonging the duration of harmless sliding where required by the operating conditions.

[0018] The cooling capacity, and thus the duration of harmless sliding, is increased by removing heat out of the transmission housing, whether by cooling the exterior of the housing, cooling the cooling medium in the housing, or through forced circulation of the cooling medium through an external cooler.

[0019] A list of drawings

[0020] Fig. 1 shows an orthogonal drawing of the invention

[0021] Fig. 2 shows an exploded 3D drawing of the invention

[0022] Fig. 3 shows an example of the application of this invention on a ship’s winch List of used call numbers

[0023] 1 . Gear with friction surfaces (also known as gear 1 )

[0024] 2. Hub

[0025] 3. Friction pad holder

[0026] 4. Pressure piston

[0027] 5. Friction pad

[0028] 6. Connecting element

[0029] 7. Bearing

[0030] 8. Distribution of the pressure medium (also known as distribution 8)

[0031] 9. Middle plate

[0032] 10. Thrust plate

[0033] 11 . Ship’s winch

[0034] 12. Winch transmission

[0035] 13. Friction clutch / dynamic brake (also known as clutch 13)

[0036] 14. Winch drum

[0037] 15. Drum brake

[0038] 16. Transmission housing

[0039] 17. Output shaft

[0040] 18. Key

[0041] Description of a way the invention can be realized

[0042] The purpose of the nomenclature for the elements used here is only to describe the implementation of the invention and not to limit the invention.

[0043] The description is based on Fig. 1 and Fig. 2.

[0044] The transmission of power and motion from the gear with friction surfaces 1 to output shaft 17 is achieved thanks to the friction created by the pressure from pressure pistons 4, through friction pads 5 on the friction surfaces of gear 1 , whereby the torque from gear 1 is transmitted by friction to hub 2, connected to output shaft 17 with key 18.

[0045] Friction pads 5 are located in hub 2, in friction pad holder 3, in middle plate 9, and in thrust plate 10. The gear with friction surfaces 1 rests on bearings 7. Connecting elements 6 connect hub 2, middle plate 9, and thrust plate 10 in a unique whole. Connecting elements 6 carry the total thrust force produced by all pressure pistons 4. The pressure medium is distributed by distribution 8.

[0046] Slipping occurs when the drive torque exceeds the clutch friction torque set. Sliding occurs between friction pads 5 pressed by pressure pistons 4 and the friction surfaces on the gear with friction surfaces 1 . During slipping, gear 1 stays still, whereas the assembly of hub 2, middle plate 9, and thrust plate 10 connected with connecting elements 6 to the main shaft 17, rotates.

[0047] The friction torque of the clutch is regulated by changing the pressure of the pressure medium acting on pressure pistons 4. Thus, changing the pressure enables controlled slippage and / or dynamic braking, while heat is taken off directly from the friction surfaces via the cooling medium.

[0048] Pressure pistons 4 can be pressed by springs instead of a pressure medium. In such a version, a lower friction torque is achieved by raising the pressure of the pressure medium, which lowers the pressure of the springs on pressure pistons 4. Thus, in addition to the functions of torque transmission and dynamic braking, the invention also offers the function of a fail-safe clutch that retains the working load in operating modes or power outages when the pressure of the pressure medium amounts to zero.

[0049] Figures: Fig. 1 , Fig. 2, and Fig. 3 show cylindrical gears with annular friction surfaces as elements of power and motion transmission. Neither the annular friction surfaces nor the gears are a fixed and / or final determinant of this invention.

[0050] Figures: Fig. 1 , Fig. 2, and Fig. 3 show an illustrative embodiment of the invention with four (4) annular friction surfaces on gear 1 , eight (8) pressure pistons 4, and eight (8) sets of friction pads 5. The annular shape of the friction surface, the said quantity of friction surfaces, and / or the number of pressure pistons 5 and friction pads 4 are not firm determinants of this invention.

[0051] Execution and application of the invention

[0052] The materials of the clutch elements presented here and the processes for achieving the final shape of the elements are listed only to describe the method of construction of the invention illustrated in Fig. 1 and Fig. 2. The invention is not limited by anything stated further / below.

[0053] The materials of the components of the friction clutch-dynamic brake can be metals, but not necessarily in all versions and not necessarily for all elements. The initial forms can be castings, forgings, blanks, preformed plates, or profiles, further formed by joining technologies. The final shapes and dimensions of the elements can be achieved by machining methods where necessary.

[0054] None of the above, namely the listed materials or raw materials and / or the technologies for forming the clutch elements, are characteristic features of this invention.

[0055] A way this invention can be applied is shown in the drawing in Fig. 3.

[0056] In the said example, the invention is applied in the composition of transmission 12 of the ship’s winch 11 , with friction clutch-dynamic brake 13 behaving in such a way that the pressure of the pressure medium acts directly on pressure pistons 4. On a ship’s winch, the invention combines the following functions:

[0057] - torque transmission at a preselected level,

[0058] - on-off clutch of the winch’s drum 14,

[0059] - dynamic braking in the event of forced unwinding of the rope from the drum.

[0060] In this specific application, when the pressure of the pressure medium amounts to zero, the on-off clutch of the drum is disengaged, so drum 14 rotates freely if it is not held by drum brake 15.

[0061] By selecting and managing the pressure of the pressure medium, the winch is set to the following operating mode features:

[0062] - traction force intensity,

[0063] - level of braking torque during dynamic braking.

[0064] By changing the pressure of the pressure medium, the specified features of the winch’s operating mode change.

[0065] To achieve the functions of the winch and to set the features of the operating mode, the version in which pressure pistons 4 are pressed by springs instead of by a pressure medium is equally valid. That way, the winch in the same friction clutch-dynamic brake acquires the function of a fail-safe clutch which, due to the friction produced by the action of the springs on pressure pistons 4, retains the force found in the rope when the pressure of the pressure medium is zero and in case of an unwanted pressure drop to zero.

Claims

PATENT CLAIMS1. Friction clutch-dynamic brake, where the transmission of torque from gear 1 to output shaft 17 is achieved by friction between friction pads 5 and the friction surfaces of gear with friction surfaces 1 , caused by the pressure of pressure pistons 4 on friction pads 5. Through that friction, the torque is transmitted to hub 2 which is connected to output shaft 17 with key 18. The clutch is shaped in such a way that a large part of the friction surfaces of gear with friction surfaces 1 is free from simultaneous friction contact, and characterized by the fact that the heat generated by friction during sliding is taken away directly from the areas of the friction surfaces of gear with friction surfaces 1 that are free from contact with friction pads 4 at that time, with the surface of these areas being more than one order of magnitude larger than the surface of small friction pads 4.

2. Friction clutch-dynamic brake, according to claim 1 , characterized by the fact that the friction intensity is regulated by a change in pressure of the friction pads 5 on gears with friction surfaces 1. That pressure is determined by the action of the pressure medium and / or springs on pressure pistons 4.

3. The friction clutch-dynamic brake, according to claim 1 , characterized by the fact that the duration of harmless sliding can be arbitrarily extended with the removal of the heat out of transmission housing 16.

4. The friction clutch-dynamic brake, according to claims 1 and 2, characterized by the fact that the same clutch also offers the function of a dynamic brake because the duration of harmless slippage is not limited.

5. The friction clutch-dynamic brake, according to claims 1 and 2, characterized by the fact that the same friction clutch-dynamic brake can offer the function of a failsafe clutch in the event that the positive pressure of the pressure medium is completely absent, provided that the clutch is designed in such a way that the springs are the ones pressing, and the pressure medium relieves pistons 4.

6. The friction clutch-dynamic brake, according to claims 1 and 2, characterized by the fact that there is no limit to use in terms of dimensions and transferable torque, or dynamic braking torque.

7. The friction clutch-dynamic brake, according to claims 1 , 2, 3, 4, and 5, characterized by the fact that the use of the invention is not excluded from application in any industrial branch.

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