A DEVICE TO OPPOSE RELATIVE ROTATIONAL MOVEMENT BETWEEN TWO ROTATABLE SHAFTS

Abstract: The arrangement to oppose difference in relative rotational speed between two rotatable shafts (1, 2) including a primary element, made to rotate with one of the shafts, and a secondary braking element, made to rotate with the other shaft, whereby both sets of braking elements could be changed from a free running position to an engaged position in order to oppose the difference in rotational speed between the two shafts. One of the shafts is carrying a rotatable unit that is showing an angled surface, circular and slightly off 90 degree from the drive shafts. This unit is connected to one side of the braking element and rotating together and sideways movable relatively to the other braking element belonging to the other shaft. Fitted to one of the shafts is a rotatable unit containing a set of movable pistons, relatively running together with the angled surface, in such a way that when a torsional movement takes place at least one of the pistons is pushing back against the fluid system pressure.

Description: A device to oppose relative rotational movement between two rotatable shafts The present invention relates to a device to oppose relative rota-tional movement between two rotatable shafts, comprising least one first braking means rotating together with one of th mentioned shafts, and at least one second braking means rotati together with, which is so adapted that the resistance of the pistons against back pressing at a least relative rotational speed between said shafts causes said axial displacement of th rotatable element and consequently a braking contact between t braking means, the other of said shafts, said two braking mean being designed to be adjusted between a releasing position and contact position so, that upon a relative rotational movement between the two shafts the braking means can be brought into a braking contact with each other in order to oppose said relati rotational movement. Background: It is a well known arrangement to use limited slip differentia to detect differences in rotational speed between two shafts, containing braking discs arranged to rotate with each of the t shafts, and to be engaged at a certain difference in rotational speed. In order to activate the engagement of the braking discs a detection device is required to detect the difference in rota tional speed, and to mechanically engage the braking discs. In previous arrangements the detection device has been complicated and has shown f nctional problems. Technical problem: The purpose of this invention is to present a simple but at the same time effective arrangement to oppose differences in speed between two rotating shafts and offer a solution to the driving and traction problems in the modern vehicle. Solution: The above mentioned purpose is according to this invention reached by means of a device, which is characterized therein that one of the shafts has an element which is rotatable together with said shaft and contains a inclined surface slightly deviating from a perpendicular position relative to the longitudinal axis of said shaft, that said element being connected with the braking means which belongs to the mentioned shaft, which braking means follows the motions of said rotating element, that said element being movable slightly axially relative to the braking means which belongs to the other shaft, that connected to and rotating with, at least one of the shafts there is a device comprising movable pistons relative to the above mentioned inclined surface and each piston placed in a chamber with pressure fluid, that the pistons are enable to cooperate with the mentioned inclined surface in such a way that upon a torsional movement of the inclined surface relative to th pistons the inclined surface is forcing at least one of the pistons into its pressure chamber against the pressurised fluid being pressurised to resist the piston movement caused by the slightest difference in relative speed variation between the two mentioned shafts, will cause the mentioned axial movement of the rotatable element and thereby a braking engagement between said mentioned braking means. Drawing references: Embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in whic fig 1 is showing a partly broken sectional view of a differentia arrangement incorporating the invention, fig 2 is showing a section II-II according to fig 1, fig 3 is showing a section through the device in a second embodiment, and fig 4 is showing a section through the device in a third embodiment. The arrangement in fig 1 is showing a conventional differential incorporating the device of this invention, the so called limite slip differential. The arrangement is showing the drive shafts 1, 2 rotatably fitted to the differential casing 4, enclosing differential pinion wheels 6, 7 rotatably fitted to the pinion shaft 5 in a right angle to the engaged rotatably differential crown wheels 9, 10 solidly fitted to the drive shafts 1, 2. This is typical arrangement in a motor driven vehicle where the drive shafts 1, 2 are driving the wheels of the vehicle. The differential arrangement is also rotatably fitted to its differential housing, not shown on this drawing. The dash-dotte line is showing the main crown wheel 11, which is fixed to the differential arrangement to rotate with it. The incoming pinion shaft, driving the crown wheel II and the differential arrangement is not shown. Inside the differential casing 4, the central part 12 is slightly movable sideways in the opening 13 where the differential pinion wheels 6, 7 are located on the shaft 5. Further more are braking elements solidly fixed to one side of the differential casing 4 and for each one of the braki elements there is a matching braking element fixed to the rotatable differential crown wheel 9, which is rotating with th outgoing drive shaft 1. Both differential crown wheels 9, 10 ar also slightly movable sideways relative to the differential casing 4. By this arrangement the drive shaft 1, 2 are floating in splines inside the differential crown wheels 9, 10. Due to t invention, the differential crown wheel 10 is showing an angled surface 16 opposite its conical teeth 44. This surface 16 is slightly of 90 degree angle from the drive shaft 2. Further mor there is a round even disc 17 that can move freely against the surface 16 inside the differential casing 4. Showing inside thi casing (see also fig 2) are several evenly pitched piston chambers 18, 19, 20, 21, 22, 23 containing movable pistons 24, 25. The inside of the piston chambers is designed to contain pressurised fluid to force the pistons 24, 25 against the disc 17. To each of the pressure chambers 18-23 is an inlet 26, 27, 28, 29, 30, 31. Due to fig 1 inlets are communicating through th openings 45, 46 in to a grove 32 in the tubular part of the differential crown wheel 10. This inlet leads on to the pressure chambers 26-31 showing on fig 2. Connected to each of the chambers is on outlet opening 34, 35 containing a valve to prevent pressurised fluid to re-enter the pressure chambers 26- 31. In a similar way, pressure valves 41 are fitted in the inlet openings, allowing fluid to enter the pressure chambers but preventing the fluid to escape. Further, according to fig 2, there is a circular bore 42 connecting all outlets 47. Through the adjustable valve 43, the circular bore 42, is leading to a not pressurised oil pan or sump. In the shown case, the adjustable valve is a piston 48 movable in its bore 49 by the spring 50 that is forcing the valve outwards from centre. Due to influence from pressurised fluid, the valve could be moved inwards to change its operation. The cylindrical part on the valve 48 has a close fit in the bore 49 but there is also a conical part 51. Further more there is on opening in the bore 49 closed by cylindrical part of the valve 48, but when the valve i moved outwards and the conical part 51 is placed over the openin the pressurised fluid is allowed to escape from the pressure chambers. The pressurised fluid that regulates the valve, is let on to the bore 49, through a radial bore not shown. This bore could communicate with the grove 32 fig 1 - and thereby employ th pressurised inlet fluid for regulation. Variations in the pressure of the inlet side 18-23 does not effect the valve operation. The inlet openings 26-31 are connected to a pressure source through the openings 45-46 to achieve constant pressure in the chambers. Due to the fact, that the sleeve 3 is rotating together with the differential casing when in motion, the pressure fluid is transferred in a known fashion, through a circular none rotating casing that is forming a seal over the sleeve 3 and surrounding the openings 45, 46. Th pressure could be rather low and still create enough force to move the pistons 24, 25 against the angled surface 16. In stable running conditions, as driving straight ahead on an even road surface with even friction, both shafts 1, 2 are rotating with same revolution speed as the differential crown wheel 10, whereb no relative rotational movement is taking place between the differential crown wheel 10 and the pistons 24, 25. At this stag the braking elements 14, 15 are running free of each other, and are not showing any difference in relative rotational speed. At the time when a difference in rotational speed will appear between the shafts 1, 2 the differential casing will rotate together with the set of pistons 24, 25 around the shaft 2 relative to the angled surface 16, and if sufficient decrease will appear in the pressure fluid, depending on the sitting of the regulating valve, the pushing in of the pistons 24, 25 in to the pressure chambers will be opposed through the volume decreas Ω P Φ P- p- rt en Ω ft rt P rt Ω P Ω en P- ti s! rt rt Ω P t. ι^ en ft I rt y-_ Ω t Ω ti Ω P P en P tr P tr tr tr tr o tr P P P tr P rt O P- tr tr P uq P- tr P- tr Hi o tr tr CD P φ H. ω en o en H P P φ Φ P φ en a en P < rt P- φ φ tn P rt P- a φ φ P P rt Φ P- Φ 0 _- ■ P- O rt Hi φ φ Φ Hi φ rt P P- P- P- t ω φ rt rt ø P P rt uq φ a 0 tr rt & en TJ P- rt rt P tr rt a a P P 3 TJ tr tr TJ o ti rt uq tr Hi Φ uq Φ φ P ti en P o tr o en rt φ P- tr P- P- uq en rt si P P- φ φ ø φ rt P P Φ o rt tr tn ti 3 φ P « Ω Hi Φ Hi P- O φ Hi Hi rt tr P- K. en tn H y- 1 a tn Hi en rt O IsJ en Φ < P- H tn o tn P H Hi Hi -1^ Φ P 1 en rt TJ ti tr rt * < ►£• ø tn tr rt rt - P- TJ Φ tr H P to P φ P Φ φ Φ . rt O H o P- S tr P Hi tr TJ -j φ tr tr P » Ω o TJ P P φ P *» Ω tr •i ti tr a P P Φ rt P tr φ Φ H- ~- P H TJ Φ φ Hi 00 ø 0 P- en a P P- O KJ Φ φ y_ φ P- P uq en en P uq P- en < 0 P P O rt Ω H O I ft en P Φ ti P tn tn P tn P P tr Hi P 1 P tn rt Ω tn Ω Φ P- a p? ti O P rt ti > uq rt a > a TJ tn rt rt P- tr HI tn P- ø P- P- tr P P en a p- rt en 0 Ω t P- Φ P- ti a t—l. x» Φ rt P- P- en ti Φ o P ft H o P 3 TJ rt P P P- XT P P- P X P P P ti 0 *l TJ Φ φ o P P P H ω tr Φ P Ω Φ Φ P 3 tr uq tn y~ P 0 en P P P X Ω P- en P- TJ a TJ P- P* s. 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P 0 tr en Φ Φ rt φ rt Ω P TJ O a P P 1 O rt i— ■ Φ P Φ tr φ TJ P a P φ tr tr Φ φ 3 3 P- P o rt 3 uq P- H P Φ Hi P en tr en en -. tr tr φ H rt Φ y- en φ φ P rt uq P- o en a < o rt 1— ■ Φ tr tr uq TJ P P- Φ P tr tr rt P φ rt en * * P P y- 1 en Φ o < P- rt P- P ft tn 0 o rt o P- P • Φ Ω a en en φ H tr X rt O P rt rt rt P P- P O P P- tr P- i . tr < Ω en P* H φ P Φ y- 1 tr 3 « j P* tr P P uq < Φ to a p- Φ P- φ φ Φ P- P P- t φ φ rt φ o O tn Φ P> uq o en φ ti 4^ P P • < rt P Φ tr Hi Hi ti t Hi . • 1 a set of braking elements 15, solidly fixed, to rotate with shaf 53. The amount of braking elements could vary due to the forces being transmitted. The sleeve 55 contains the angled surface 16 and washer 17. In a stable running position, both drive shaft 52 53 are rotating with same revolutionary speed, whereby the sleev 55 is in the right outside position and both seats of braking elements 14, 15 are running free of each other. By a change of the relative rotational speed, the angled surface 16 is turned relatively to the set of pistons 24, 25 and thereby trying to push the pistons in to pressure chambers 18, 19. Depending on th chosen setting of the valve 43 (fig 2) the system pressure will prevent the pistons 24, 25 to be pushed in, and the mentioned torsional movement will instead force the sleeve 55 sideways wit its braking elements 15 to engage against the other braking elements 14 belonging to the casing 54, whereby the fastest rotating shaft will be slowed down and receive the same rotational speed as the other shaft. Fig 4 is showing the third embodiment according to the invention, applied in a gear box differential. The main features are similar to the first example where a conventional differential is used in conjunction with th device due to the invention. Similar to the first example, there is a set of movable pistons 24, 25 inside pressure chambers, running in line with the shafts 1, 2. In principle the same flui system could be used as in the first example, with its entrance 60 from the pressure source, and via the valve 61 communicating with the pressure chambers 18, 19 and additional valves only allowing inflow from the pressure source. In a similar fashion, each pressure chamber has got an outlet to the circular bore 42, and each of the outlets fitted with the valve only allowing outlet from the pressure chambers but preventing inflow. The difference between the first and the third design, is that the rotatable unit 64 with the angled surface 65 is formed as a separate part, not attached to any of the differential crown wheels and separately sideways movable relative to the shaft 1 on splines and rotating together. The rotating unit 64 is also containing the braking elements 15, where as the other set of braking elements 14 is fixed to the differential casing 4. 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TJ Ω y- tr Φ O tn Φ Ω a P P- p- a 3 φ 3 H. < O P- ϋ * Ω y-" ti en P P* rt rt P ti φ φ P rt H Φ Ω P en < φ Φ P P P l- 1 O a φ 3 o * P- O • ! Φ ti rt rt P H Φ rt Φ P P < P 3 en P< en < • ! P P- rt O en en rt 0 o rt Φ P P tr Ω a 3 1-- P ft O P tn < φ P XT Ω en to P rt en P P P P \Q ft P φ P o a < H. en < 0 Φ P- P H. Φ Φ O en O . tr 3 ø P- P- ft T 0 P- a en 0 Ω ø Φ •<! P- uq ti en P rt O Ω ø P- P o φ O ti P rt Ω tr P- 1 P- P TJ P- Φ ø y-> Ω P O φ P- rt rt TJ P* O P] Hi < φ φ φ Φ H tr P- P rt a Ω a O uq o H. O P P- P a P * PC φ Φ tn P ti Φ *«• ti en uq rt O Φ 0 a en P O P rt P H Φ ft P 3 Ω TJ P rt P- 0 a P rt o a T ø TJ P 4 0 O rt P uq rt tr TJ P 1 tr uq φ tr Φ a P P P " i pr O o H. P" Φ a P tn ø tn P Ω tr Φ P- P- P- φ P P P Φ P- <; P- tr P- P ~i rt -. Φ a P P- o ti Φ rt O _- ■ O O P 3 P uq ft § a rt P Φ rt P φ P tn tr tr P < a XT rt y-- Ω TJ P- ø Φ P Hi P P- P- < a Φ ^ tr P P ti uq P- φ Φ tr P- Φ 0 φ P o * Φ o rt φ P- 3 P- Φ φ < rt Ω a φ Ω Ω o P Φ P P rt *» ti P a P P a P Φ P Hi φ tn ti tr P P- O XT Φ tr tr P- P rt uq Φ P P- P P P en P- a ft Hi P en Φ H o P rt *< P P TJ P- a O XT rt P 1 P a P- tn Hi -. P- Φ rt rt • Hi P- P rt tr Φ P P P 3 tr rt φ φ φ φ O P Φ O ti ft P- rt o Φ g φ- 3 < rt ti o rt P 0 Φ y-< a P 1 Hi tr rt o H. P O P " ^ φ φ tr Φ P ft ω en P P φ en φ tr P- Hi TJ O φ ti φ P Hi P- rt φ P- P- P P ti P rt Φ rt H φ tn tr φ O < φ P* rt Ω P o en P- rt rt tn en P- rt tr > 0 Φ tr Hi φ P en tr Φ rt uq rt rt P P tr en o φ P- a φ rt O tr tr tr uq P- P P a en P- φ Φ φ P- tn P

Claims: Claims : 1. A device to oppose relative rotational movement between two rotatable shafts, comprising at least one of first braking means rotating together with one of the mentioned shafts, and at least one second braking means rotating together with a rotatable housing designed to cooperate so as to bring along the other of said shafts, said two braking means being designed to be adjuste between a releasing position and a contact position so, that upo a relative rotational movement between the two shafts the brakin means can be brought into a braking contact with each other in order to oppose said relative rotational movement, c h a r a c¬ t e r i z e d therein that one of the shafts has an element whic is rotatable together with said shafts and contains a inclined surface slightly deviating from a perpendicular position relativ to the longitudinal axis of said shaft, that said element being connected with the braking means which belongs to the mentioned shaft, which braking means follows the motions of said rotating element, that said element being movable slightly axially relative to the braking means which belongs to the other shaft, that connected to and rotating with, at least one of the shafts there is a device comprising movable pistons relative to the above mentioned inclined surface and each pistons are enable to cooperate with the mentioned inclined surface in such a way that upon a torsional movement of the inclined surface relative to th pistons the inclined surface is forcing at least one of the pistons into its pressure chamber against the pressurised fluid being pressurised to resist the piston movement caused by the slightest difference in relative speed variation between the two mentioned shafts, will cause the mentioned axial movement of the rotatable element and thereby a braking element between said braking means. 2. A device according to claim 1, c h a r a c t e r i z e d therein, that the ability of the pistons for pressing action is controllable, involving a controllable axial displaceability of said element and consequently braking action of the braking mea by said corporation between the pistons and the oblique surface 3. A device according to claim 1, characterized therein, that said rotatable element (64) carries said first braking means (15). 4. A device according to claim 1, characterized therein, that the cylinder chambers (18-23) communicates over an outlet (34, 35) for each chamber with a common angular channel (42) which communicates with a central outlet for discharge of pressure medium over a choking means (43) positioned in the central outlet, that each outlet (34, 35) from the cylinder chambers ha a return valve (40) provided to prevent a backstream of the pressure medium to the cylinder chambers. 5. A device according to claim 4, charaterized therein, that to each cylinder chamber (18-23) lead inlets (26-30), provided wit a return valve for each inlet, arranged to allow a flow of pressure medium to the cylinder chambers, but prevent a backflo from the cylinder chambers. 6. A device according to claim 2 and 4, characterized therein, that said choking means (43) is controllable for the purpose of controlling the resistance of the pistons against return pressin action.

Inventors: JOHANSSON SIGVARD, JOHANSSON, SIGVARD
Applicants: JOHANSSON SIGVARD, JOHANSSON, SIGVARD
Application year: 1988
Main classification: F16H1
IPC codes: B60K17, B60K23, F16D25, F16H48