CA1271147A - Control coupling - Google Patents
Control couplingInfo
- Publication number
- CA1271147A CA1271147A CA000485936A CA485936A CA1271147A CA 1271147 A CA1271147 A CA 1271147A CA 000485936 A CA000485936 A CA 000485936A CA 485936 A CA485936 A CA 485936A CA 1271147 A CA1271147 A CA 1271147A
- Authority
- CA
- Canada
- Prior art keywords
- clutch
- plates
- coupling
- annular
- piston
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 230000008878 coupling Effects 0.000 title abstract description 103
- 238000010168 coupling process Methods 0.000 title abstract description 103
- 238000005859 coupling reaction Methods 0.000 title abstract description 103
- 239000007788 liquid Substances 0.000 abstract description 14
- 239000012530 fluid Substances 0.000 abstract description 6
- 238000006243 chemical reaction Methods 0.000 description 15
- 230000005540 biological transmission Effects 0.000 description 13
- 230000000694 effects Effects 0.000 description 3
- 230000001419 dependent effect Effects 0.000 description 2
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 229920000136 polysorbate Polymers 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 125000006850 spacer group Chemical group 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D7/00—Slip couplings, e.g. slipping on overload, for absorbing shock
- F16D7/02—Slip couplings, e.g. slipping on overload, for absorbing shock of the friction type
- F16D7/024—Slip couplings, e.g. slipping on overload, for absorbing shock of the friction type with axially applied torque limiting friction surfaces
- F16D7/025—Slip couplings, e.g. slipping on overload, for absorbing shock of the friction type with axially applied torque limiting friction surfaces with flat clutching surfaces, e.g. discs
- F16D7/027—Slip couplings, e.g. slipping on overload, for absorbing shock of the friction type with axially applied torque limiting friction surfaces with flat clutching surfaces, e.g. discs with multiple lamellae
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
- B60K17/00—Arrangement or mounting of transmissions in vehicles
- B60K17/34—Arrangement or mounting of transmissions in vehicles for driving both front and rear wheels, e.g. four wheel drive vehicles
- B60K17/348—Arrangement or mounting of transmissions in vehicles for driving both front and rear wheels, e.g. four wheel drive vehicles having differential means for driving one set of wheels, e.g. the front, at one speed and the other set, e.g. the rear, at a different speed
- B60K17/35—Arrangement or mounting of transmissions in vehicles for driving both front and rear wheels, e.g. four wheel drive vehicles having differential means for driving one set of wheels, e.g. the front, at one speed and the other set, e.g. the rear, at a different speed including arrangements for suppressing or influencing the power transfer, e.g. viscous clutches
- B60K17/3505—Arrangement or mounting of transmissions in vehicles for driving both front and rear wheels, e.g. four wheel drive vehicles having differential means for driving one set of wheels, e.g. the front, at one speed and the other set, e.g. the rear, at a different speed including arrangements for suppressing or influencing the power transfer, e.g. viscous clutches with self-actuated means, e.g. by difference of speed
- B60K17/351—Arrangement or mounting of transmissions in vehicles for driving both front and rear wheels, e.g. four wheel drive vehicles having differential means for driving one set of wheels, e.g. the front, at one speed and the other set, e.g. the rear, at a different speed including arrangements for suppressing or influencing the power transfer, e.g. viscous clutches with self-actuated means, e.g. by difference of speed comprising a viscous clutch
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D35/00—Fluid clutches in which the clutching is predominantly obtained by fluid adhesion
- F16D35/005—Fluid clutches in which the clutching is predominantly obtained by fluid adhesion with multiple lamellae
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D47/00—Systems of clutches, or clutches and couplings, comprising devices of types grouped under at least two of the preceding guide headings
- F16D47/06—Systems of clutches, or clutches and couplings, comprising devices of types grouped under at least two of the preceding guide headings of which at least one is a clutch with a fluid or a semifluid as power-transmitting means
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Transportation (AREA)
- Hydraulic Clutches, Magnetic Clutches, Fluid Clutches, And Fluid Joints (AREA)
- Retarders (AREA)
- Arrangement And Driving Of Transmission Devices (AREA)
Abstract
ABSTRACT
A control coupling comprising an outer coupling part 1, an inner coupling part 2, a first set of annular plates 6 therebetween constituting a viscous shear coupling and a second set of annular plates 12 constituting a friction clutch, wherein a fluid tight axially movable piston 3 is disposed between the sets of plates, arranged to be movable axially to urge the plates 12 into torque transmitting engagement by expansion of the liquid in the viscous shear coupling. The movement of the piston is limited by a stop 17, and springs 8 are interposed between the piston and friction clutch plates so that the maximum torque transmissible by the coupling is limited. Under such conditions, the torque transmissible by the viscous shear coupling is negligible compared with that of the friction clutch. The coupling may be utilized between axles of a motor vehicle, or in a differential unit. in a further embodiment, Figure 4, the friction clutch may be electro-magnetically disengageable.
A control coupling comprising an outer coupling part 1, an inner coupling part 2, a first set of annular plates 6 therebetween constituting a viscous shear coupling and a second set of annular plates 12 constituting a friction clutch, wherein a fluid tight axially movable piston 3 is disposed between the sets of plates, arranged to be movable axially to urge the plates 12 into torque transmitting engagement by expansion of the liquid in the viscous shear coupling. The movement of the piston is limited by a stop 17, and springs 8 are interposed between the piston and friction clutch plates so that the maximum torque transmissible by the coupling is limited. Under such conditions, the torque transmissible by the viscous shear coupling is negligible compared with that of the friction clutch. The coupling may be utilized between axles of a motor vehicle, or in a differential unit. in a further embodiment, Figure 4, the friction clutch may be electro-magnetically disengageable.
Description
~ his invention relates to a control coupling which includes a viscous shear coupling and a friction clutch, the control coupling comprising inner and outer coupling parts defining an annular space therebetween, and two sets of annular plates disposed in such annular space, each set comprising mutually interleaved plates with alternate ones thereof rotationally fast with one of said coupling parts and the remaining ones thereof rotationally fast with the other coupling part, the plates of one of said sets being spaced from one another and a viscous liquid being accommodated therebetween to form a viscous shear coupling, and the plates of the other set being movable by a piston arrangement into engagement with one another for torque transmission between the coupling parts by friction between the plates. Such a control coupling will hereafter be referred to as a coupling of the kind specified.
~.~
A control coupling of the kind specified is disclosed in US PS 4058027. In that coupling, the purpose of the plates which constitute the friction clutch is to compensate for the drop in torque transmissible by the viscous shear coupling when its temperature~rises, and to assist the temperature of the viscous coupling to fall by partly taking over the transmission of torque. Expansion of the viscous liquid as its temperature rises is used to cause the friction clutch plates to be urged together, by way of a differential piston arrangement.
One disadvantage of such a control coupling is that even when torque is being transmitted between the .:
.:
- : ... .
. .
' , : - ' ' ' ' '' ' ' coupling parts by the friction clutch plates, the viscous shear coupling still participates to a considerable extent in torque transmission. The apportionment of torque between the viscous shear coupling and friction clutch is highly temperature dependent, so that torque transmitted by the control coupling as a whole is relatiYely uncontrollable.
Yet a further disadvantage is that the plates forming the viscous shear coupling are not separated from the plates forming the friction clutch, so that both sets of plates have to operate in the presence of the same liquid. ~uch liquid will usually be selected for its properties in relation to the viscous shear coupling, but such a liquid may not be the optimum for the friction clutch.
Yet another disadvantage is that the maximum torque transmissible by the control coupling as a whole cannot be clearly defined, as it depends upon the temperature of the viscous shear coupling elements thereof.
It is the object of the present invention to provide a control coupling in which these disadvantages are overcome or reduced, i.e. its torque transmission characteristics should be capable of being well defined in relation to temperature and its maximum torque transmission capability should be largely independent of the transmission behaviour of the viscous shear coupling.
~urther, it should be possible to operate the viscous shear coupling and friction clutch in the presence of appropriate different media.
According to the present invention, we provide a control coupli~ng of the kind specified wherein a fluid ,~
. .
.
. .
tight axially movable annular piston i8 disposed between said sets of plates, said piston being arranged, by movement in one direction upon expansion of the liquid in said viscous shear coupling, to urge said plates forming the friction clutch into torque transmitting engagement with one another, the movement of said piston in said direction being limited by stop means and there being spring means interposed between said piston and said friction clutch plates, the torque transmissible by said viscous shear coupling being negligibly low compared with that transmitted by said friction clutch when the latter is transmitting torque.
une advantage of a control coupling according to the invention is that uncontrollable temperature dependent torque transmitting behaviour of the viscous shear coupling cannot lead to uncontrollable torque transmission by the control coupling as a whole, since the torque is determined by the friction clutch and the maximum torque is limited by contact of the piston with said stop means, and the characteristics of the spring means interposed between the piston and pla-tes forming the friction clutch. Any further increase in pressure of the liquid in the viscous shear coupling would not increase the torque transmitted by the control coupling as a whole.
A control coupling according to the invention may be disposed in a drive line connecting two axles of a motor vehicle. ~hen thus installed, the maximum torque capable of being transmitted by the control coupling is preferably slightly higher than the maximum torque which ca~ be introduced by the vehicle's engine into such inter-axle drive line. When we refer to "axles" of a vehicle, it is to be understood that we do not :, -::
-.
necessarily mean live axles or, indeed, any particularsuspension and drive arrangement, but rather a pair of drivable wheels, either at the front or rear, of the vehicle.
In such an installation, the control coupling is capable of automatically causing engagement of a second drive axle when any wheel slip occurs at the main drive axles~ ~imultaneously, excessive drive line torques are avoided. In effect, the control coupling provides for automatic engagement of four wheel dri~e in a vehicle which normally has only two wheel drive, without requiring an inter-axle differentialO
A control coupling according to the invention may also be used in a differential unit, to limit slippage between two outputs thereof whilst still being capable of accommodating differences in output speeds due to cornering.
A further feature of the present invention is concerned with the ability rapidly to discontinue torque transmission by the friction clutch of the control coupling when requiredD This may be required, for example, for safety reasons.
It has been proposed, in G~ P~ 414662, that torque transferrable by a fluid clutch can be controlled by changing the quantity of fluid therein, and if all fluid is withdrawn from the clutch into storage chambers, no torque can be transferred. ~uch changes in torque 9 however, are very slow and thus the arrangement is not suitable where a rapid change into a free wheeling condition is necessary.
.
-'~: ", ~7~ 7 According to this further feature of the invention, at the end of said set of plates which forms said friction clutch of the control coupling, remote from said piston, there may be provided an annular reaction member which is spring biased towards said piston by a second spring means which is stronger than the first said spring means associated with said piston, said reaction member being movable away from said piston against said second spring means by an electro-magnet through a distance such that when said piston contacts said stop means, said first spring means is completely unloaded.
Thus, when the reaction member has been moved by the electro-magnet, because the first spring means is completely unloaded the friction clutch can transmit no torque whatsoever. ~he change to such "freewheeling"
condition is instantaneous by operation of the electro-magnet.
~ control coupling having this feature may be useful in a motor vehicle where an automatically engaged further drive axle may be required to be disengaged, e.g. when the brakes of the vehicle are applied. This may be necessary if the vehicle is equipped with an anti-lock bra~ing system with the operation of which there might be interference when the further axle is driven. The electro-magnet of the control coupling can easily be brought into operation by application of the vehicle's brakes, so that the wheels of the further axle act as undriven wheels during braking.
:
This principle may also be applied to differential units which achieve a "limited slip" effect by use of a control coupling according to the invention, - and whose effect is required to be eliminated during ,~
, , . .
:~ ' - : .
:~ ' ~L~'7~1~'7 braking.
The invention will now be described by way of example with reference to the accompanying drawings, of which:-~ igure l is a longitudinal section through part of acontrol coupling according to the invention;
Figure 2 is a schematic illustration of the application of a control coupling according to the invention in a motor vehicle drive line;
Figure ~ is a section showing the application of a control coupling according to the invention to a differential unit;
Figure 4 is a longitudinal section through part of a further embodiment of control coupling according to the invention.
Referring firstly to ~igure l of the drawings, the control coupling of which part is illustrated comprises an outer coupling part t, which is in the form of two components having abutting flanges secured together by bolts, and an inner coupling part 2 which also comprises two components abutting one another. The inner coupling part defines a through bore 16 which has axially extending splines 15, and the two components of the inner part 2 are maintained rotationally fast with one another by virtue of their engagement, in use, with an externally splined shaft fi-tting in the bore 16. ~he outer coupling part l is provided with a flange 14 having screw-threaded recesses 13 for a bolted connection to a driving flange on a shaft element.
' ~
,~
.
.~ ' .
~.~'7~14~7 Two sets of annular plates are disposed between the coupling parts l 9 2, one set of plates constituting a viscous shear coupling and the other set of plates constituting a friction clutch. The viscous shear coupling comprises a set of mutually interleaved plates 6, of which alternate plates are rotationally fast with the outer coupling part l and the remaining plates are rotationally fast with the inner coupling part 2. The plates are spaced from one another by spacers 7, e.g.
wire rings, and are limited in their axial movement by outer and inner axial fixing rings 18a, 18b.
'~he friction clutch 11 comprises a set of mutually interleaved plates 12, of which again alternate ones are rotationally fast with the outer coupling part l and the other alternate plates fast with the inner coupling part
~.~
A control coupling of the kind specified is disclosed in US PS 4058027. In that coupling, the purpose of the plates which constitute the friction clutch is to compensate for the drop in torque transmissible by the viscous shear coupling when its temperature~rises, and to assist the temperature of the viscous coupling to fall by partly taking over the transmission of torque. Expansion of the viscous liquid as its temperature rises is used to cause the friction clutch plates to be urged together, by way of a differential piston arrangement.
One disadvantage of such a control coupling is that even when torque is being transmitted between the .:
.:
- : ... .
. .
' , : - ' ' ' ' '' ' ' coupling parts by the friction clutch plates, the viscous shear coupling still participates to a considerable extent in torque transmission. The apportionment of torque between the viscous shear coupling and friction clutch is highly temperature dependent, so that torque transmitted by the control coupling as a whole is relatiYely uncontrollable.
Yet a further disadvantage is that the plates forming the viscous shear coupling are not separated from the plates forming the friction clutch, so that both sets of plates have to operate in the presence of the same liquid. ~uch liquid will usually be selected for its properties in relation to the viscous shear coupling, but such a liquid may not be the optimum for the friction clutch.
Yet another disadvantage is that the maximum torque transmissible by the control coupling as a whole cannot be clearly defined, as it depends upon the temperature of the viscous shear coupling elements thereof.
It is the object of the present invention to provide a control coupling in which these disadvantages are overcome or reduced, i.e. its torque transmission characteristics should be capable of being well defined in relation to temperature and its maximum torque transmission capability should be largely independent of the transmission behaviour of the viscous shear coupling.
~urther, it should be possible to operate the viscous shear coupling and friction clutch in the presence of appropriate different media.
According to the present invention, we provide a control coupli~ng of the kind specified wherein a fluid ,~
. .
.
. .
tight axially movable annular piston i8 disposed between said sets of plates, said piston being arranged, by movement in one direction upon expansion of the liquid in said viscous shear coupling, to urge said plates forming the friction clutch into torque transmitting engagement with one another, the movement of said piston in said direction being limited by stop means and there being spring means interposed between said piston and said friction clutch plates, the torque transmissible by said viscous shear coupling being negligibly low compared with that transmitted by said friction clutch when the latter is transmitting torque.
une advantage of a control coupling according to the invention is that uncontrollable temperature dependent torque transmitting behaviour of the viscous shear coupling cannot lead to uncontrollable torque transmission by the control coupling as a whole, since the torque is determined by the friction clutch and the maximum torque is limited by contact of the piston with said stop means, and the characteristics of the spring means interposed between the piston and pla-tes forming the friction clutch. Any further increase in pressure of the liquid in the viscous shear coupling would not increase the torque transmitted by the control coupling as a whole.
A control coupling according to the invention may be disposed in a drive line connecting two axles of a motor vehicle. ~hen thus installed, the maximum torque capable of being transmitted by the control coupling is preferably slightly higher than the maximum torque which ca~ be introduced by the vehicle's engine into such inter-axle drive line. When we refer to "axles" of a vehicle, it is to be understood that we do not :, -::
-.
necessarily mean live axles or, indeed, any particularsuspension and drive arrangement, but rather a pair of drivable wheels, either at the front or rear, of the vehicle.
In such an installation, the control coupling is capable of automatically causing engagement of a second drive axle when any wheel slip occurs at the main drive axles~ ~imultaneously, excessive drive line torques are avoided. In effect, the control coupling provides for automatic engagement of four wheel dri~e in a vehicle which normally has only two wheel drive, without requiring an inter-axle differentialO
A control coupling according to the invention may also be used in a differential unit, to limit slippage between two outputs thereof whilst still being capable of accommodating differences in output speeds due to cornering.
A further feature of the present invention is concerned with the ability rapidly to discontinue torque transmission by the friction clutch of the control coupling when requiredD This may be required, for example, for safety reasons.
It has been proposed, in G~ P~ 414662, that torque transferrable by a fluid clutch can be controlled by changing the quantity of fluid therein, and if all fluid is withdrawn from the clutch into storage chambers, no torque can be transferred. ~uch changes in torque 9 however, are very slow and thus the arrangement is not suitable where a rapid change into a free wheeling condition is necessary.
.
-'~: ", ~7~ 7 According to this further feature of the invention, at the end of said set of plates which forms said friction clutch of the control coupling, remote from said piston, there may be provided an annular reaction member which is spring biased towards said piston by a second spring means which is stronger than the first said spring means associated with said piston, said reaction member being movable away from said piston against said second spring means by an electro-magnet through a distance such that when said piston contacts said stop means, said first spring means is completely unloaded.
Thus, when the reaction member has been moved by the electro-magnet, because the first spring means is completely unloaded the friction clutch can transmit no torque whatsoever. ~he change to such "freewheeling"
condition is instantaneous by operation of the electro-magnet.
~ control coupling having this feature may be useful in a motor vehicle where an automatically engaged further drive axle may be required to be disengaged, e.g. when the brakes of the vehicle are applied. This may be necessary if the vehicle is equipped with an anti-lock bra~ing system with the operation of which there might be interference when the further axle is driven. The electro-magnet of the control coupling can easily be brought into operation by application of the vehicle's brakes, so that the wheels of the further axle act as undriven wheels during braking.
:
This principle may also be applied to differential units which achieve a "limited slip" effect by use of a control coupling according to the invention, - and whose effect is required to be eliminated during ,~
, , . .
:~ ' - : .
:~ ' ~L~'7~1~'7 braking.
The invention will now be described by way of example with reference to the accompanying drawings, of which:-~ igure l is a longitudinal section through part of acontrol coupling according to the invention;
Figure 2 is a schematic illustration of the application of a control coupling according to the invention in a motor vehicle drive line;
Figure ~ is a section showing the application of a control coupling according to the invention to a differential unit;
Figure 4 is a longitudinal section through part of a further embodiment of control coupling according to the invention.
Referring firstly to ~igure l of the drawings, the control coupling of which part is illustrated comprises an outer coupling part t, which is in the form of two components having abutting flanges secured together by bolts, and an inner coupling part 2 which also comprises two components abutting one another. The inner coupling part defines a through bore 16 which has axially extending splines 15, and the two components of the inner part 2 are maintained rotationally fast with one another by virtue of their engagement, in use, with an externally splined shaft fi-tting in the bore 16. ~he outer coupling part l is provided with a flange 14 having screw-threaded recesses 13 for a bolted connection to a driving flange on a shaft element.
' ~
,~
.
.~ ' .
~.~'7~14~7 Two sets of annular plates are disposed between the coupling parts l 9 2, one set of plates constituting a viscous shear coupling and the other set of plates constituting a friction clutch. The viscous shear coupling comprises a set of mutually interleaved plates 6, of which alternate plates are rotationally fast with the outer coupling part l and the remaining plates are rotationally fast with the inner coupling part 2. The plates are spaced from one another by spacers 7, e.g.
wire rings, and are limited in their axial movement by outer and inner axial fixing rings 18a, 18b.
'~he friction clutch 11 comprises a set of mutually interleaved plates 12, of which again alternate ones are rotationally fast with the outer coupling part l and the other alternate plates fast with the inner coupling part
2. These plates, as for the plates 6, may have their connection to the coupling parts established by splined peripheral profiles.
Between the plates constituting the viscous shear coupling and the plates constituting the friction clutch, there is disposed an annular piston ~. Annular seals 4 render the piston fluid tight, while permitting axial movement thereof. lhe chamber containing the plates 6 is filled with an appropriate liquid of known type for use in a viscous shear coupling, and the chamber containing the friction clutch plates 12 either is filled with an appropriate liquid for service in such conditions, or else contains no liquid at all.
lmmediately to the right of the piston ~, with reference to the drawing, there is disposed an annular pressure plate 10, which is rotationally fast with the outer coupling part 1 and movable axially relative ~' ' .: ' ', ~
~7~7 thereto. ~he piston 3 has a plurality of circumferentially spaced bores open towards the pressure plate 10 and extending through bosses 9 on the piston, and the pressure plate has projections 19 exten~ing into the bores in bosses 9. Compression springs 8 are provided in the bores in the piston 3, abutting the closed ends of such bores and the ends of projections 19.
By virtue of the engagement of projections 19 in bosses 9, the piston 3 is, with the pressure plate 10, rotationally fast with the outer coupling part 1.
Movement of piston towards the plates of friction clutch 11 is limited by engagement of the piston with a stop 17. Opposite the pressure plate 10, the end one of the plates 12 abuts a reaction member 30 fixed to the outer coupling par-t 1 and having sealing engagement with the inner coupling part 2 by way of a seal 31.
In use, if due to slip between transmission components to which the inner and outer coupling parts 1, 2 are connected there is relative angular movement between these parts, the plates 6 forming the viscous shear coupling 5 tran~mit torque between the coupling parts by the shearing action on the viscous liquid there-be-tween, in known manner. The shear forces which occur in the liquid will cause a rise in the tempera-ture thereof and consequent expansion, which will displace piston 3 to the right with reference to the drawing, i.e.
torwards the friction clutch 11. Springs 8 are thus compressed. Torque is transmitted between the coupling parts 1, 2 by friction between the plates 12~ the magnitude of such transmitted torque depending on the strength of springs 8. Stop 17, limiting movement of piston 3, ensures that the torque transmissible by the friction clutch 11 is limited to a maximum value. ~he . .
, ~L~'7~
length of the springs 8 is preferably selected so that there is no axial force whatsoever acting on the plates of the friction clutch when there is no load on the coupling, i.e. the piston 3 has not been displaced by any expansion of the viscous liquid in the viscous shear coupling 5.
It will be appreciated that springs ~, shown as helical springs, may be replaced by springs of other configurations. For example, spring washers may be employed and it is possible to use such washers in a manner such that any wear occuring in the friction plates 12 would cause the force exerted on the friction plates to remain constant or nearly so, or even possibly increase.
Referring now to ~igure 2 of the drawings, there is shown in principle how a control coupling according to the invention may be utilized in a motor vehicle. Ihe illustrated vehicle has a forwardly mounted engine 20, transmission 21, and driven front wheels by way of drive shafts 22. A power take-off from the transmission 21 is arranged to drive the rear axle 23 of the vehicle by way of a control coupling 24 according to the invention, and a longitudinally extending drive shaft 32. If the front wheels slip, the relative rotation which occurs between the parts of the control coupling cause torque to be transmitted to the rear wheels of the vehicle.
' Referring now to ~igure 3 of the drawings, this shows how a control coupling according to the invention may be incorporated in a differential unit. ~he differential unit comprises a casing 33, input pinion 34, crown wheel 25, planet carrier 35 and planet bevels as 36 carried on pin 26. ~he bevels as 36 engage with side ' :
;:
. .
~.~7~147 gears 37 splined -to stub shafts 38 provided with respective outpu-t flanges 27. ~he inner coupling part 2 is connected to one of the stub shafts 38, and the outer coupling part 1 is formed by part of the planet carrier 35. The viscous shear coupling and friction clutch parts 11, 5 of the control coupling according to the invention are referenced in ~'igure 3, and piston 3 therebetween.
The control coupling ensures that if the wheel connected to one output o~ the differential unit slips, its maximum torque is available for the other driven wheel.
Referring now to Figure 4 of the drawings, certain parts of the control coupling there illustrated correspond to parts in the embodiment of ~'igure 1, and such parts have corresponding reference numerals to the parts of ~igure 1 with the addition of 100. Thus, the control coupling comprises an outer coupling part 101, a two part inner coupling part 102 with a bore 116 having splines 115~ A shaft with which the inner coupling part engages is indicated at 132, The coupling comprises a viscous shear coupling portion 105 with plates 106, spaces 107 and fixing means 118a, 118b, and a friction clutch arrangement 111 having plates 112, and a pressure plate 110. There is a piston 103 with seals 104, and projections 119 from pressure plate 110 extending into bosses 109 on the piston with Gompression springs 108 therein. A stop 117 limits movement of the piston. Thus far, the operation of the control coupling is as above described in relation to Figure 1.
In this embodiment, however, the one of the plates 112 which is furthest from piston 103 abuts a reaction member 128 which includes an outwardly extending flange .. . . . .
' ~ ' ' ' .
portion. The reaction member 128 is spring biased towards the piston 103 by a second spring means in the form of a stack of belville washers 129, which engage the reaction member and react against a stop such as a circlip 131 engaging the inner coupling part 102. The force of the second spring means provided by washers 129 is greater than that of the springs 108, so that the reaction member normally adopts the position illustrated in which it abuts the outer coupling part 101, and is not moved from this position even when the piston 103 loads the plates 112 into torque transmitting frictional engagement. The reaction member 128 faces an electro-magnet 130, spaced therefrom and supported by being fixed to a transmission casing part 133, a seal 13~ being provided between the casing part 133 and the shaft 132.
When the electro-magnet 130 is energised, it pulls the reaction member 128 away from the piston 103, against the spring washers 129. To minimize the force required to be exerted by the electro-magnet to hold the reaction member 128, the spring washers 129 may be arranged to provide a decreasing spring rate.
The distance by which the reaction member 128 is moved by the electro-magnet 130 is selected so as to be greater than the permissible movement of piston 103 before it meets stop 117. Thus, there is no longer any possibility of any torque being transmitted by the plates 112 of the friction clutch 111, and a friction clutch is instantly brought to a completely free-wheeling condition when the electro-magnet 130 is energised.
To avoid any possibility of rubbing of the reaction member 128 on the electro-magnet 130, travel of the reaction member towards the magnet must be limited by some form of stopO Conveniently, spring washers 129 may be arrangea to be completely compressed to provide such ~:
, . , , , . :
limitation of movement of the reaction member.
A control coupling as shown in Figure 4 is useful in the case where a vehicle has an anti-lock braking system and torque transmission by the friction clutch section of the control coupling is required to be discontinued so as not to ~nterfere with the operation of such an anti-lock system. it is easy to arrange for the electro-magnet of the control system to be energized when the vehicle's brakes are applied, e.g. by way of the switch which operates the vehicle's brake lights.
A control coupling as shown in Figure 4 may also be utilized in a differential unit~ if the limited slip action of a differential is required to be disabled in conjunction with the operation of an anti-lock braking sy~tem.
~ ' .
';~.: :
': :
- . ~ , -: ~ . ,
Between the plates constituting the viscous shear coupling and the plates constituting the friction clutch, there is disposed an annular piston ~. Annular seals 4 render the piston fluid tight, while permitting axial movement thereof. lhe chamber containing the plates 6 is filled with an appropriate liquid of known type for use in a viscous shear coupling, and the chamber containing the friction clutch plates 12 either is filled with an appropriate liquid for service in such conditions, or else contains no liquid at all.
lmmediately to the right of the piston ~, with reference to the drawing, there is disposed an annular pressure plate 10, which is rotationally fast with the outer coupling part 1 and movable axially relative ~' ' .: ' ', ~
~7~7 thereto. ~he piston 3 has a plurality of circumferentially spaced bores open towards the pressure plate 10 and extending through bosses 9 on the piston, and the pressure plate has projections 19 exten~ing into the bores in bosses 9. Compression springs 8 are provided in the bores in the piston 3, abutting the closed ends of such bores and the ends of projections 19.
By virtue of the engagement of projections 19 in bosses 9, the piston 3 is, with the pressure plate 10, rotationally fast with the outer coupling part 1.
Movement of piston towards the plates of friction clutch 11 is limited by engagement of the piston with a stop 17. Opposite the pressure plate 10, the end one of the plates 12 abuts a reaction member 30 fixed to the outer coupling par-t 1 and having sealing engagement with the inner coupling part 2 by way of a seal 31.
In use, if due to slip between transmission components to which the inner and outer coupling parts 1, 2 are connected there is relative angular movement between these parts, the plates 6 forming the viscous shear coupling 5 tran~mit torque between the coupling parts by the shearing action on the viscous liquid there-be-tween, in known manner. The shear forces which occur in the liquid will cause a rise in the tempera-ture thereof and consequent expansion, which will displace piston 3 to the right with reference to the drawing, i.e.
torwards the friction clutch 11. Springs 8 are thus compressed. Torque is transmitted between the coupling parts 1, 2 by friction between the plates 12~ the magnitude of such transmitted torque depending on the strength of springs 8. Stop 17, limiting movement of piston 3, ensures that the torque transmissible by the friction clutch 11 is limited to a maximum value. ~he . .
, ~L~'7~
length of the springs 8 is preferably selected so that there is no axial force whatsoever acting on the plates of the friction clutch when there is no load on the coupling, i.e. the piston 3 has not been displaced by any expansion of the viscous liquid in the viscous shear coupling 5.
It will be appreciated that springs ~, shown as helical springs, may be replaced by springs of other configurations. For example, spring washers may be employed and it is possible to use such washers in a manner such that any wear occuring in the friction plates 12 would cause the force exerted on the friction plates to remain constant or nearly so, or even possibly increase.
Referring now to ~igure 2 of the drawings, there is shown in principle how a control coupling according to the invention may be utilized in a motor vehicle. Ihe illustrated vehicle has a forwardly mounted engine 20, transmission 21, and driven front wheels by way of drive shafts 22. A power take-off from the transmission 21 is arranged to drive the rear axle 23 of the vehicle by way of a control coupling 24 according to the invention, and a longitudinally extending drive shaft 32. If the front wheels slip, the relative rotation which occurs between the parts of the control coupling cause torque to be transmitted to the rear wheels of the vehicle.
' Referring now to ~igure 3 of the drawings, this shows how a control coupling according to the invention may be incorporated in a differential unit. ~he differential unit comprises a casing 33, input pinion 34, crown wheel 25, planet carrier 35 and planet bevels as 36 carried on pin 26. ~he bevels as 36 engage with side ' :
;:
. .
~.~7~147 gears 37 splined -to stub shafts 38 provided with respective outpu-t flanges 27. ~he inner coupling part 2 is connected to one of the stub shafts 38, and the outer coupling part 1 is formed by part of the planet carrier 35. The viscous shear coupling and friction clutch parts 11, 5 of the control coupling according to the invention are referenced in ~'igure 3, and piston 3 therebetween.
The control coupling ensures that if the wheel connected to one output o~ the differential unit slips, its maximum torque is available for the other driven wheel.
Referring now to Figure 4 of the drawings, certain parts of the control coupling there illustrated correspond to parts in the embodiment of ~'igure 1, and such parts have corresponding reference numerals to the parts of ~igure 1 with the addition of 100. Thus, the control coupling comprises an outer coupling part 101, a two part inner coupling part 102 with a bore 116 having splines 115~ A shaft with which the inner coupling part engages is indicated at 132, The coupling comprises a viscous shear coupling portion 105 with plates 106, spaces 107 and fixing means 118a, 118b, and a friction clutch arrangement 111 having plates 112, and a pressure plate 110. There is a piston 103 with seals 104, and projections 119 from pressure plate 110 extending into bosses 109 on the piston with Gompression springs 108 therein. A stop 117 limits movement of the piston. Thus far, the operation of the control coupling is as above described in relation to Figure 1.
In this embodiment, however, the one of the plates 112 which is furthest from piston 103 abuts a reaction member 128 which includes an outwardly extending flange .. . . . .
' ~ ' ' ' .
portion. The reaction member 128 is spring biased towards the piston 103 by a second spring means in the form of a stack of belville washers 129, which engage the reaction member and react against a stop such as a circlip 131 engaging the inner coupling part 102. The force of the second spring means provided by washers 129 is greater than that of the springs 108, so that the reaction member normally adopts the position illustrated in which it abuts the outer coupling part 101, and is not moved from this position even when the piston 103 loads the plates 112 into torque transmitting frictional engagement. The reaction member 128 faces an electro-magnet 130, spaced therefrom and supported by being fixed to a transmission casing part 133, a seal 13~ being provided between the casing part 133 and the shaft 132.
When the electro-magnet 130 is energised, it pulls the reaction member 128 away from the piston 103, against the spring washers 129. To minimize the force required to be exerted by the electro-magnet to hold the reaction member 128, the spring washers 129 may be arranged to provide a decreasing spring rate.
The distance by which the reaction member 128 is moved by the electro-magnet 130 is selected so as to be greater than the permissible movement of piston 103 before it meets stop 117. Thus, there is no longer any possibility of any torque being transmitted by the plates 112 of the friction clutch 111, and a friction clutch is instantly brought to a completely free-wheeling condition when the electro-magnet 130 is energised.
To avoid any possibility of rubbing of the reaction member 128 on the electro-magnet 130, travel of the reaction member towards the magnet must be limited by some form of stopO Conveniently, spring washers 129 may be arrangea to be completely compressed to provide such ~:
, . , , , . :
limitation of movement of the reaction member.
A control coupling as shown in Figure 4 is useful in the case where a vehicle has an anti-lock braking system and torque transmission by the friction clutch section of the control coupling is required to be discontinued so as not to ~nterfere with the operation of such an anti-lock system. it is easy to arrange for the electro-magnet of the control system to be energized when the vehicle's brakes are applied, e.g. by way of the switch which operates the vehicle's brake lights.
A control coupling as shown in Figure 4 may also be utilized in a differential unit~ if the limited slip action of a differential is required to be disabled in conjunction with the operation of an anti-lock braking sy~tem.
~ ' .
';~.: :
': :
- . ~ , -: ~ . ,
Claims (5)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS :
1. A control clutch mechanism comprising: an inner clutch part and an outer clutch part defining an annular space therebetween;
a viscous control unit and a frictional clutch unit, each consisting of a multi-plate clutch, each of said viscous control unit and said frictional clutch unit consisting of a set of plates arranged in said annular space formed between said clutch parts with each set consisting of plates which are alternately arranged rotatively fixed, respectively, to said inner and outer clutch parts with the plates of said viscous control unit being axially spaced apart a distance which is greater than the thickness of the plates;
an axially movable annular piston slidingly arranged in fluid-tight engagement between said viscous control unit and said frictional clutch unit;
a pressure plate located between said annular piston and said frictional clutch unit;
at least one pressure spring operatively interposed between said annular piston and said pressure plate;
said viscous control unit being structured to transmit a negligibly low nominal torque as compared with said frictional clutch unit;
first stop means limiting an axial sliding path of said annular piston;
an annular flange on said frictional clutch unit at an end thereof facing away from said annular piston;
second spring means against which said annular flange is supported, said second spring means exerting a force which is greater than a force of said at least one pressure spring;
second stop means for limiting axial movement of said annular flange; and electromagnetic means for generating a magnetic field for moving said annular flange against said second stop means against the force of said second spring means;
travel of said annular flange effected by said magnetic field being such that loading on said at least one pressure spring is completely relieved when said annular piston rests against said first stop means.
a viscous control unit and a frictional clutch unit, each consisting of a multi-plate clutch, each of said viscous control unit and said frictional clutch unit consisting of a set of plates arranged in said annular space formed between said clutch parts with each set consisting of plates which are alternately arranged rotatively fixed, respectively, to said inner and outer clutch parts with the plates of said viscous control unit being axially spaced apart a distance which is greater than the thickness of the plates;
an axially movable annular piston slidingly arranged in fluid-tight engagement between said viscous control unit and said frictional clutch unit;
a pressure plate located between said annular piston and said frictional clutch unit;
at least one pressure spring operatively interposed between said annular piston and said pressure plate;
said viscous control unit being structured to transmit a negligibly low nominal torque as compared with said frictional clutch unit;
first stop means limiting an axial sliding path of said annular piston;
an annular flange on said frictional clutch unit at an end thereof facing away from said annular piston;
second spring means against which said annular flange is supported, said second spring means exerting a force which is greater than a force of said at least one pressure spring;
second stop means for limiting axial movement of said annular flange; and electromagnetic means for generating a magnetic field for moving said annular flange against said second stop means against the force of said second spring means;
travel of said annular flange effected by said magnetic field being such that loading on said at least one pressure spring is completely relieved when said annular piston rests against said first stop means.
2. A control clutch mechanism according to claim 1.
wherein said mechanism is arranged in a driveline connecting two axles with a torque capacity of the control clutch mechanism being slightly higher than a maximum torque introduced by an engine into said driveline.
wherein said mechanism is arranged in a driveline connecting two axles with a torque capacity of the control clutch mechanism being slightly higher than a maximum torque introduced by an engine into said driveline.
3. A control clutch mechanism according to claim 1.
wherein said control clutch is used as a differential brake.
wherein said control clutch is used as a differential brake.
4. A control clutch mechanism comprising: an inner clutch part and an outer clutch part defining an annular space therebetween;
a viscous control unit and a friction clutch unit each consisting of a multi-plate clutch; each of said viscous control unit and said frictional clutch unit consisting of a set of plates arranged in said annular space formed between said clutch parts, with each set consisting of plates which are alternately arranged rotatively fixed respectively to said inner and outer clutch parts, with the plates of said viscous control unit being held spaced apart an axial distance which is greater than the thickness of the plates;
an axially movable annular piston slidingly arranged in fluid-tight engagement between said viscous control unit and said frictional clutch unit;
first stop means limiting an axial sliding path of said annular piston;
a pressure plate located between said annular piston and said frictional clutch unit;
first spring means operatively interposed between said annular piston and said pressure plate;
said viscous control unit being structured to transmit a negligibly low nominal torque as compared with said frictional clutch unit;
an annular flange on said frictional clutch unit at an end thereof facing away from said annular piston;
second spring means against which said annular flange is supported, said second spring means exerting a force which is greater than a force of said first spring means;
second stop means for limiting axial movement of said annular flange; and electromagnetic means for generating a magnetic field for moving said annular flange against said second stop means against the force of said second spring means;
travel of said annular flange effected by said magnetic field being such that loading on said first spring means is completely relieved when said annular piston rests against said first stop means.
a viscous control unit and a friction clutch unit each consisting of a multi-plate clutch; each of said viscous control unit and said frictional clutch unit consisting of a set of plates arranged in said annular space formed between said clutch parts, with each set consisting of plates which are alternately arranged rotatively fixed respectively to said inner and outer clutch parts, with the plates of said viscous control unit being held spaced apart an axial distance which is greater than the thickness of the plates;
an axially movable annular piston slidingly arranged in fluid-tight engagement between said viscous control unit and said frictional clutch unit;
first stop means limiting an axial sliding path of said annular piston;
a pressure plate located between said annular piston and said frictional clutch unit;
first spring means operatively interposed between said annular piston and said pressure plate;
said viscous control unit being structured to transmit a negligibly low nominal torque as compared with said frictional clutch unit;
an annular flange on said frictional clutch unit at an end thereof facing away from said annular piston;
second spring means against which said annular flange is supported, said second spring means exerting a force which is greater than a force of said first spring means;
second stop means for limiting axial movement of said annular flange; and electromagnetic means for generating a magnetic field for moving said annular flange against said second stop means against the force of said second spring means;
travel of said annular flange effected by said magnetic field being such that loading on said first spring means is completely relieved when said annular piston rests against said first stop means.
5. A control clutch mechanism according to claim 4.
wherein said electromagnetic means operates to switch said control clutch mechanism into a freewheeling state.
wherein said electromagnetic means operates to switch said control clutch mechanism into a freewheeling state.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19843426460 DE3426460C1 (en) | 1984-07-18 | 1984-07-18 | Control clutch |
| DEP3426460.4-12 | 1984-07-18 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1271147A true CA1271147A (en) | 1990-07-03 |
Family
ID=6240951
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000485936A Expired CA1271147A (en) | 1984-07-18 | 1985-06-28 | Control coupling |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS6138226A (en) |
| CA (1) | CA1271147A (en) |
| DE (1) | DE3426460C1 (en) |
Families Citing this family (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT392038B (en) * | 1984-12-12 | 1991-01-10 | Steyr Daimler Puch Ag | DRIVE ARRANGEMENT FOR TWO DRIVEN MOTOR VEHICLE AXLES |
| DE3539484C1 (en) * | 1985-11-07 | 1986-12-18 | Uni-Cardan Ag, 5200 Siegburg | Controllable coupling |
| JPH0351532Y2 (en) * | 1986-11-14 | 1991-11-06 | ||
| DE3707106A1 (en) * | 1987-03-05 | 1988-09-15 | Uni Cardan Ag | Self-locking differential |
| JPH0717162B2 (en) * | 1987-03-27 | 1995-03-01 | 豊田工機株式会社 | Torque transmission device |
| AT395396B (en) * | 1987-04-28 | 1992-12-10 | Steyr Daimler Puch Ag | DRIVE ARRANGEMENT FOR MOTOR VEHICLES WITH DRIVED FRONT AND REAR AXLES |
| ATA106887A (en) * | 1987-04-29 | 1992-07-15 | Steyr Daimler Puch Ag | DRIVE ARRANGEMENT FOR ALL-WHEEL DRIVE MOTOR VEHICLES |
| JP2579644B2 (en) * | 1987-09-28 | 1997-02-05 | 豊田工機株式会社 | Hydraulic control device |
| JPH01206126A (en) * | 1987-10-24 | 1989-08-18 | Toyota Motor Corp | Power transmission on-off mechanism |
| JP2527022B2 (en) * | 1989-01-21 | 1996-08-21 | トヨタ自動車株式会社 | Power transmission mechanism |
| JP2536144B2 (en) * | 1989-04-07 | 1996-09-18 | トヨタ自動車株式会社 | Power transmission mechanism |
| JP2540947B2 (en) * | 1989-07-17 | 1996-10-09 | トヨタ自動車株式会社 | Power transmission device |
| AT395344B (en) * | 1991-03-08 | 1992-11-25 | Steyr Daimler Puch Ag | LIQUID FRICTION CLUTCH WITH ADJUSTABLE GAP WIDTH |
| DE19650040C2 (en) * | 1995-12-21 | 1999-04-15 | Gkn Viscodrive Gmbh | Clutch unit |
| DE19902388C2 (en) | 1999-01-22 | 2001-05-23 | Gkn Automotive Ag | Controllable clutch |
| US6413183B1 (en) * | 1999-04-14 | 2002-07-02 | Tochigi Fuji Sangyo Kabushiki Kaisha | Power transmission apparatus |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4058027A (en) * | 1976-07-09 | 1977-11-15 | Gkn Transmissions Limited | Control couplings |
-
1984
- 1984-07-18 DE DE19843426460 patent/DE3426460C1/en not_active Expired
-
1985
- 1985-06-28 CA CA000485936A patent/CA1271147A/en not_active Expired
- 1985-07-15 JP JP15435085A patent/JPS6138226A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPH038406B2 (en) | 1991-02-06 |
| JPS6138226A (en) | 1986-02-24 |
| DE3426460C1 (en) | 1985-12-05 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |