WO1989001576A1

WO1989001576A1 - Fluid-coupled clutch

Info

Publication number: WO1989001576A1
Application number: PCT/GB1988/000662
Authority: WO
Inventors: David William Hardie
Original assignee: David William Hardie
Priority date: 1987-08-12
Filing date: 1988-08-11
Publication date: 1989-02-23
Also published as: GB8719112D0; AU2139988A

Abstract

A fluid-coupled clutch for connecting an input drive (10) and an output drive (12) comprises a hollow casing (14) connected with one of the input drive (10) and the output drive (12), the casing (14) containing a transmission fluid and being provided with a plurality of fluid-engaging projections (42, 42a) on its interior. The other of the input drive (10) and the output drive (12) is provided with a plurality of blades (44) housed within the casing (14). Means (80, 82, 84, 86) are provided for varying the pitch of the blades (44) in order to adjust the engagement of the clutch.

Description

DESCRIPTION FLUID-COUPLED CLUTCH

The present invention relates to fluid-coupled clutches, and in particular, but not exclusively, to fluid-coupling clutches for motor vehicles.

It is an object of the present invention to provide a fluid-coupled clutch which provides a variable coupling between an input and an output drive, yet which is relatively straightforward in construction.

In accordance with the present invention, a fluid-coupled clutch for connecting an input drive and an output drive is characterised by a hollow casing connected with one of the input drive and the output drive, the casing containing a transmission fluid and being provided with a plurality of fluid-engaging projections on its interior, a plurality of variable blades, vanes, flaps or other fluid-engageable projections mounted on the other of the input drive and the output drive and housed within the casing, and means for varying the pitch, inclination or orientation of the variable blades, vanes, flaps or other fluid-engageable projections in order to adjust the engagement of the clutch.

In a preferred embodiment, the casing comprises a generally hemispherical hollow dome connected to one of the input drive and the output drive, the other of the input drive and the output drive passing sealingly through the apex region of the dome.

Preferably, the fluid-engaging projections on the interior of the casing comprise a plurality of spaced- apart ribs or fins.

In one embodiment, the input drive is connected to the casing, and the blades are connected to the output drive. In this embodiment, as the input drive rotates, so does the casing, and the projections on the interior of the casing impart a rotational motion to the ^"transmission fluid. By varying the pitch, inclination or orientation of the blades, vanes, flaps or other fluid-engageable projections, the force exerted by the rotating fluid may be varied. When the planes of the blades or other fluid-engageable projections are aligned with the direction of motion of the fluid (i.e. edge-on), little or no force is exerted on them, but as the blades or other fluid- engageable projections are inclined to the direction of motion of the fluid, the rotating fluid exerts a force thereon and on the output drive connected thereto.

In an alternative embodiment, the blades or other fluid-engageable projections are connected to the input drive, and the casing is connected to the output drive. As the input drive rotates, the blades or other fluid-engageable projections can impart a rotational motion to the fluid in the casing, depending on the pitch, inclination or orientation of the blades or the like. If the blades or the like aligned with their direction of motion, little or no force is exerted on the fluid, which remains stationary, and hence no motion is imparted to the casing or the output shaft. As the blades or the like are inclined to their direction of motion, they impart a rotational motion to the fluid, and this rotational motion interacts with the projections on the interior of the casing, which causes the casing and the output drive to rotate. By way of example only, specific embodiments of the present invention will now be described, with reference to the accompanying drawings, in which;-

Fig. 1 is a side view, partly cut away, of a first embodiment of fluid-coupled clutch in accordance with the present invention, in an engaged condition;

Fig. 2 is a side view, partly cut away, of the clutch of Fig. 1, but in a disengaged condition;

Fig. 3 is a view in the direction of arrows III- III of Fig. 2;

Fig. 4 is a detail cross-section of the actuating mechanism of the clutch of Fig. 1;

Fin. 5 is a side view, partly cut away, of a second embodiment of fluid-coupling clutch in accordance with the pr-esent invention;

Fig. 6 is a perspective view of a portion of a clutch of Fig. 5;

Fig. 7 is a side view, partly cut away, of a third embodiment of fluid-coupled clutch, in accordance with the present invention; and

Fig. 8 is a perspective view, showing the fluid- coupling portion of the clutch of Fig. 7 in more detai 1.

Referring firstly to Figs. 1 to 3, the clutch is adapted to couple a power input shaft 10, driven by an engine crankshaft (not illustrated), to a propeller shaft 12 which is in turn connected via a gearbox (not illustrated) to the driven wheels of the vehicle. The clutch is in the form of a generally hemispherical casing 14 which is split along a plane 16 parallel to a flat base 18 of the casing into a base portion 20 and an outer portion 22, the two portions, in use, being joined by a plurality of bolts (not shown) passing through six equally-spaced aligned apertures 24 in co-operating peripheral annular flanges 26, 28 on the base and outer portions 20, 22 respectively.

The end of the input shaft 10 is provided with a circular flange 30 which is bolted onto the base 18 of the casing 14, thereby causing the casing 14 to rotate with the input shaft 10. The output shaft 12 passes sealingly through an aperture in the casing 10 by virtue of an annular shaft seal 32, and is supported in bearings 34 housed in the casing 14, the shaft lying with its elongate axis along the axis of symmetry of the hemispherical casing 14, perpendicular to the base 18. The end 36 of the output shaft 12 is of a reduced diameter, and is received in a further bearing 38 housed within a short upstanding cylindrical tube 40 extending from the base 18.

The inner surface of the casing is provided with thirty-six equally-spaced planar ribs or fins 42, each formed of a straight portion 42a_ extending radially from the cylindrical tube 40 and projecting perpendicularly from the base 18, and which is contiguous with an arcuate portion 42b_^ projecting from the internal wall of the casing and extending almost to the apex of the hemispherical casing 14.

The output shaft 12 is provided with four equally- spaced variable pitch planar propeller blades 44. Each blade is pivotally mounted in a pivot 46 within the output shaft 12 and is adapted to pivot about an axis perpendicular to the longitudinal axis of the output shaft 12. The blades are each rotatable through ninety degrees between the position illustrated in Fig. 1 and the position illustrated in Fig. 2. Radially outwardly from each pivot 46 is a generally cylindrical portion formed into a pinion 48. Each pinion engages with a rack portion 50 of a respective push rod 52, the push rods 52 extending through respective bores in the output shaft 12 extending parallel to the longitudinal axis of the shaft. The rods 52 are actuated by means of a collar 54 which is mounted on a reduced diameter portion 12' of the shaft 12 by means of bearings 56. Further bearings 58 mounted on the collar 54 engage the push rods 52 when the collar is displaced.

The collar 54 is pivotally connected to a conventional clutch fork, such that when the clutch pedal is depressed, the collar 54 is displaced in the direction of the arrows in Fig. 4, to the left as shown in that figure. The bearings 58 thereby contact the ends of the rods 52 and displace them, causing the rack portions 50 to rotate the pinion portions 48 and thereby causing the propeller blades to pivot. The blades 44 are biassed, by means of compression springs 60 extending between a stop 62 on each rod 52 and the annular shoulder 64 formed by the conjunction of the reduced diameter portion 12' of th^p shaft 12 with the main portion thereof, to assume the position shown in Figs_ 1 and 4, i.e. with the planes of the blades 44 parallel to the longitudinal axis of the shaft 12.

In use, the blades 44 are within the casing 14 of the clutch, and, as best seen in Fig. 1, the blades are spaced slightly from the ribs or fins 42. It will be seen that it is therefore necessary for the shape of the blades to be generally that of a truncated quadrant. The casing 14 is filled with oil, such as automatic gearbox oil.

When the drive shaft is rotating, the casing 14 also rotates as stated before, and the motion of the planar ribs 42 causes the oil within the casing to be rotated at a high speed. If the clutch pedal is depressed, the propeller blades are pivoted by the push rods 52 to assume the orientation shown in Fig. 2, i.e. edge-on to the circular motion of the fluid. In this orientation, the oil flows easily past the blades 44, and very little force, if any, is exerted by the rapidly-rotating fluid on the blades, and the output shaft 12 remains stationary.

As the clutch pedal is gradually released, the blades pivot and present their faces at a shallow angle to the direction of motion of the oil. This causes the oil to exert a rotating force on the blades, which thus causes the output shaft 12 to rotate. As the clutch pedal is further released, the blades present a steeper angle to the direction -of motion of the fluid, and the steeper the angle (i.e. the more the -clutch pedal is released) the greater the force exerted on the blades 44 and the output shaft 12. When the clutch pedal is fully released, the planes of the blades 44 are perpendicular to the direction of motion of the rotating fluid, and the linkage between the input shaft 10 and the output shaft 12 becomes very firm.

By varying the depression of the clutch and thereby varying the amount by which the blades 44 pivot, the degree of engagement of the clutch can be controlled between virtually complete disengagement (as illustrated in Fig. 2) and virtually complete engagement (as illustrated in Fig. 4).

A second embodiment is illustrated in Figs. 5 and 6. The hemispherical casing 14 is identical to that of the first embodiment, but the pivotal ly-mounted blades 44 of the first embodiment have been replaced with two parallel spaced apart discs 68, 70 fixedly attached to the output shaft 12. As best seen in Fig. 6, each disc 68, 70 is provided with eight, equally angularly-spaced, generally rectangular planar flaps or blades 72, each of which is pivotally mounted along one of its long edges to its associated disc 68, 70 by means of a hinge 74. Each flap or blade 72 is adapted to be pivoted between a disengaged position, in which the flap or blade is seated in an associated aperture 76 of the disc and whose plane is thereby parallel to the plane of the disc (as shown in full lines) and an engaged position in which the plane of flap or blade 72 is inclined at an angle of about thirty degrees to the plane of the disc (as shown in chain dot).

The flaps or blades 72 are pivotable by -means of actuating rods 78 which are mounted with their longitudinal axes parallel to the plane of the discs. Each rod 78 is connected to a respective ^' flap or blade 72 along the hinge 74, such that rotation of the rods 78 causes pivoting of the flaps or blades 72 about the hinges 74. The rods are provided with an enlarged pinion portion 80 mounted within the output shaft 12 and are actuated by means of push rods 82 having a rack portion 84, passing along the output shaft 12. Each p bh rod 82 is arranged to actuate one flap or blade 72 on each of the discs 68, 70, and eight push rods in total are therefore required. The push rods 82 may be displaced by means of a collar 86 mounted on a reduced diameter portion of the output shaft 12, similar to the collar 54 of the first embodiment. A clutch pedal (not illustrated) is connected to the collar such that by depressing the pedal the collar to the right as shown in Fig. 5, thereby bringing the flaps or blades 72 parallel with the plates 68, 70. The clutch pedal is spring-loaded, and release of the pedal causes the collar to move to the left as shown in Fig. 5.

In use, the casing 14 is filled with oil and the casing 14 rotates with the engine, thereby imparting a circular motion to the oil, by virtue of the fins 42. When the clutch pedal is depressed, the flaps or blades 72 lie parallel to the planes of the discs 68, 70, and the oil slips easily past the blades, thereby imparting little or no momentum to the blades. As the clutch pedal is released, the flaps or blades 72 become inclined to the plane of the discs 68, 70, and the circulating ^"oil thereby imparts an impulse on the flaps or blades 72, causing the output shaft 12 to rotate. The more the clutch pedal is released, the more the flaps or blades 72 become inclined to the plane of the discs 68, 70, and the greater the engagement of the clutch, until at full engagement the outputs shaft 12 rotates substantially with the input shaft 10.

By varying the depression of the clutch and thereby varying the inclination of the flaps or blades 72, the degree of engagement of the clutch can be controlled between the virtually complete disengagement and virtually complete engagement.

A third embodiment is illustrated in Figs. 7 and 8. The generally hemispherical casing 14 is identical to that of the first and second embodiments; but the output shaft 12' is connected to a single, thickened disc 90. As in the other embodiment, an end 36 of the output shaft 12 is received in a bearing 38 housed within a short upstanding cylindrical tube 40 extending from the base 18.

As best seen in Fig. 8, the periphery of the disc 90 is provided with eight pivotally mounted flaps or vanes 92, equally angularly spaced around the disc, attached to the disc by means of respective pivots 94 having a pivotal axis parallel to the rotational axis of the disc, and each flap or vane 92 has the same radius of curvature as the circumference of the disc 90. Each flap or vane 92 is movable between a first (non-engaging) position, illustrated in full lines, in which each flap or vane 92 is seated in a correspondingly-shaped recess 96 such that the curvature of each flap is substantially contiguous with and flush with that of the disc 90, and a. second (engaging) position, illustrated in chain dot, in which each flap or vane 92 is pivoted outwardly about its pivot 94. The outward pivoting is achieved by means of a plurality of respective rods 98, each of which is pivotally connected to a respective flap or vane 92 and to a common operating tube 100 which surrounds the output shaft 12' and which extends a short distance into the disc 90 along the rotational axis of the disc, as best seen in Fig. 7. The shaft is mounted in the bearings 34 and abuts the seal 32. By rotating the operating tube, the flaps or vanes may be pivoted between the two aforementioned positions. The operating tube is normally biassed by means of a spring (not shown) in the direction indicated by arrow A in Fig . 8.

In use, the input shaft 10 is rotated by the vehicle engine, causing the casing to rotate. As before, the planar ribs or fins 42 on the interior cause the fluid contained in the casing to rotate. If the clutch pedal of the vehicle is depressed, the operating tube 100 will have been rotated in the direction of arrow B of Fig. 8, causing the flaps or vanes 92 to be drawn into the correspondingly shaped recesses 96, such that they lie flush with the peripheral surface of the -disc 90. In this case, the rotating fluid flows smoothly past the disc, and since the flaps or vanes are flush with the disc, virtually no momentum is imparted to the disc.

As the clutch pedal is released, the spring- loading of the tube 100 causes it to rotate in the direction of arrow A, such that the vanes or flaps pivot outwardly from the periphery of the disc, as shown in chain dot in Fig. 8. By varying the depression of the clutch, the projection of the flaps or vanes is varied, and consequently the engagement of the clutch can be varied.

This embodiment is intended to make maximum use of the momentum of fluid which will be forced radially outwardly as a result of its rotation.

However, the invention is not restricted to the details of the foregoing embodiments. In particular, the embodiments illustrated can be used "in reverse", i.e. with the shaft 12, 12' as the input shaft and shaft 10 as the output shaft. As before, the collar 54 or 86 or the tube 100 is pivotally connected to the clutch fork, and when the clutch is depressed the blades, flaps or vanes, 44, 72 or 92, which rotate with the crankshaft of the engine, are edge-on to the longitudinal axis of the shafts 10, 12 or flush with the edge of the disc 90, as appropriate. The blades 44 or the disc or discs 68, 70 or 90 thus travel easily through the oil within the casing, and impart little or no momentum to the oil. The casing 14 and the output shaft 10 therefore remain stationary. As the clutch pedal is gradually released, the planes of the blades 44 or 72 become slightly less inclined to the longitudinal axis of the input shaft 12 or the flaps or vanes 92 project from the edge of the disc 90. This causes the blades to impart momentum to the oil, which then travels in a circular motion. As the oil rotates, some of its momentum is imparted to the planar ribs 42, which thus causes the output shaft 10 to. rotate. As the clutch pedal is released further, more momentum is imparted to the oil and the output shaft 10 is thus forced to travel faster. Eventually, at full clutch pedal release (i.e. maximum clutch engagement), the linkage between the input shaft 12 and the output shaft becomes very firm. Also, by varying the depression of the clutch, and thereby varying the amount by which the blades 44 or 72 pivot, or by which the flaps or vanes 92 project, the amount of momentum imparted to the oil, and hence the force transmitted to the output shaft 10, can be varied between virtually complete disengagement and virtually complete engagement.

Claims

1. A fluid-coupled clutch for connecting an input drive and an output drive (10, 12), characterised by a hollow casing (14) connected with one of the input drive and the output drive (10, 12), the casing containing a transmission fluid and being provided with a plurality of fluid-engaging projections (42) on its interior, a plurality of variable blades, vanes flaps or other fluid-engageable projections (44) mounted on the other of the input drive and the output drive (10, 12) and housed within the casing, and means (50, 52, 54) for varying the pitch, inclination or orientation of the variable blades, vanes, flaps or other fluid-engageable projections (44) in order to adjust the engagement of the clutch.

2. A fluid-coupled clutch as claimed in claim 1, wherein the casing (14) comprises a generally hemispherical hollow dome (22) connected to one of the input drive and the output drive (10, 12), the other of the input drive and the output drive (10, 12) passing sealingly through the apex region of the dome (22).

3. A fluid-coupled clutch as claimed in claim 1 or claim 2, wherein the fluid-engaging projections (42) on the interior of the casing comprise a plurality of spaced-apαrt ribs or fins.

4. A fluid-coupled clutch as claimed in any of claims 1 to 3, comprising a single set of variable- pitch blades (44) mounted at substantially the same longitudinal position on the other of the input drive and the output drive (10, 12).

5. A fluid-coupled clutch as claimed in any of claims 1 to 4, further comprising a disc (68) mounted on the other of the input drive and the output drive (10, 12), the disc being provided with a plurality of flaps (72), each of which is movable between a first orientation in which it lies substantially parallel to the plane of the disc and a second position in which the plane of the flap is inclined to the plane of the disc.

6. A fluid-coupled clutch as claimed in claim 5, wherein the flaps (72) are pivotally mounted on the disc (68).

7. A fluid-coupled clutch as claimed in claim 5 or claim 6, comprising a plurality of flaps (92) pivotally mounted on the periphery of the disc (90).

8. A fluid-coupled clutch as claimed in claim 7, wherein the pivotal -axes of the pivots of the flaps (92) are substantially parallel to the rotational axis of the disc (90) .

9. A fluid-coupled clutch as claimed in claim 5 or claim 6, comprising a plurality of discs (68, 70), each disc being provided with a plurality of flaps (72).

10. A fluid-coupled clutch as claimed in any of claims 1^' to 9, comprising biassing means (60) for urging the blades (44;72) into fluid-coupling engagement with the casing (14).

11. A fluid-coupled clutch as claimed in any of the claims 1 to 10, wherein the input drive (10) is connected to the casing (14), and the blades (44;72) are connected to the output drive (12).

12. A fluid-coupled clutch as claimed in any of claims 1 to 10, wherein the blades (44;72) are connected to the input drive (10), and the casing (14) is connected to the output drive (12).