Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
  • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
  • F01L1/34—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift
  • F01L1/344—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear
  • F01L1/356—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear making the angular relationship oscillate, e.g. non-homokinetic drive
• • 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
  • F16H—GEARING
  • F16H35/00—Gearings or mechanisms with other special functional features
  • F16H35/02—Gearings or mechanisms with other special functional features for conveying rotary motion with cyclically varying velocity ratio

Definitions

• THIS INVENTION relates to a rotary drive arrangement for rotating a driven member so that the speed of rotation increases and decreases, or "oscillates" during a revolution of the driven member.
• the drive arrangement finds particular application in applying oscillatory pulses to the rotation of a camshaft, but the basic principles can be applied to any shaft, component or axle arrangement wherein such rotational characteristics are deemed desirable. ,
• a rotary drive arrangement for rotating a driven member so that, the speed of rotation oscillates during .a revolution of the driven member, which arrangement comprises a rotatable driving member, a follower member rotatable with the driving member and slidable relative to the driving member transversely
• Figure I is an end elevation, partly in section, of part of one embodiment of rotary drive arrangement according to the invention.
• SUBSTi ⁇ UTi ⁇ SHEET Figure 2 is ⁇ side elevation, partly in section, of the Figure I embodiment of rotary drive arrangement
• Figure 3 is a plan view, partly in section, of the rotary drive arrangement of Figure 2; .
• Figure 4 is a view like Figure I of a rotary drive arrangement having a modified follower member
• Figure 5 is a side elevation, partly in section, of another embodiment of a rotary drive arrangement according to the invention.
• Figure 6 is an end elevation of a rotary drive embodying the invention and illustrating a modified coupling between the follower member and a driven member; and .
• Figure 7 is a side elevation, partly in section, of the arrangement of Figure 6.
• the present invention offers a simple solution to the problem of providing variable valve timing and behaviour in internal combustion engines, in that the necessary components are, in themselves, extremely basic in mechanical realisation and, therefore, cost effective.
• a rotary drive arrangement comprises a reciprocable follower I mounted upon a square-section drive- shaft within an annular cam 9.
• the follower I contacts the annular cam 9 via a free-running roller 2, but this roller could be replaced by a solid follower point.
• follower I is provided with ⁇ slotted centre 3. The sides of the slot 3 are parallel wth the side walls of the square-section shaft 4, and are shown to be In bearing maintained communication.
• the amount of travel which is permitted to the follower I relative to the shaft 4 is, in this example, restricted by the length of slot 3.
• the lateral axis i.e. the sliding axis, of follower I is, in Figure I , shown at 90° to a datum line "X" - "X".
• Lever 5 is provided with a pin - located eccentrically of the axis of rotation of shaft 4, and the eccentric pin 6 is provided with a flange 20. Therefore, if the pin 6 is brought into contact with a resistive loading, any rotation of the shaft 5 will result in the follower I being caused to rotate, with roller 2 maintained in forced contact with annular cam 9.
• annular cam 9 were perfectly circular, then there would be no change in the attitude of the follower I , i.e. it would simply describe a perfectly circular motion. However, annular cam 9 is provided with an undulating inner cam surface provided, in this example, with four lobes 8. Therefore, if contact is maintained between the roller 2 and the annular cam 9, a reciprocating motion will be experienced by follower I , relative to the shaft 4.
• shaft 4 is fixed to or part of an input shaft 18 which, in turn, is fixed to or part of a mounting flange 16, to which is fixed a driving sprocket wheel 19. Therefore, any rotational movement of sprocket wheel 19 will result in similar rotational movement of shaft 4.
• Input shaft 18 is bearing located within a journal assembly I .
• Follower I I s indicated as being a free-sliding component, located upon the shaft 4 and maintained in correct location by two side mounted guides 10 and I I , these preventing any sideways movement away from the desired reciprocative attitude of follower I .
• the two guides are fixed to, or part of shaft assembly 18, 4.
• FIG. 3 shows that the eccentric pin 6 is located within a slightly elongated aperture situated in a cranked arm 12 which is fixed to, or part of, a camshaft 13.
• annular cam 9 is carried by an annular carrier 7 which is capable of being rotated concentrically of the axis of rotation of shaft 4.
• the oscillatory pulse sequence can thus be advanced and/or retarded in relation to the basic rotary input timing by adjusting the angular position of the carrier 7.
• the carrier 7 is provided with a means (not shown) for rotating it and locking it in the adjusted position.
• a worm/worm-wheel assembly having the necessary "locking" lead angle is one example of a suitable adjusting means, but any suitable repositioning means can be incorporated, and the necessary control (manual or otherwise) mechanism (not shown) can be added in order to maintain a desired functional envelope.
• the annular cam 9 has four undulations, or lobes, each equal in size, shape and profile and with a similar rise and fc-ril.
• any desired number of cam lobes may be provided, each having a desired size and shape.
• the lobes may thus all be the same, or may all be different.
• the positioning, profile and general intention can be designed to suit any desired pulse "shape", and in this respect, the eventual event as described by the individual valve, can be designed according to oscillatory accelerations and declerations of a repositional nature.
• FIG. 4 shows ⁇ variation of the arrangement of Figures I to 3, in which the main reciprocative axis is parallel with the axis passing through the centres of the eccentric pin 6 and the roller 2. All other components are similar to those of Figure I. However, it will be seen that there are only three lobes 8 indicated in this drawing. Figure 4 illustrates that the reciprocating axis can be varied in order to benefit from angles of mechanical advantage, or disadvantage, depending upon the requirements. It is assumed that annular cam carrier 7 is either fixed or adjustable. The three lobes 8 are situated 120° apart. The direction of rotation of the shaft 4 is assumed to be anti-clockwise.
• the in-line six cylinder internal combustion engine presents certain difficulties in respect of "nose” mounted devices, i.e. devices mounted at the; end of the camshaft, in that, the six events (intake or exhaust) have a certain degree of overlap. Therefore, it is necessary to divide the camshaft 13 Into two separate shafts, and provide, for example, a concentric quill shaft down the inside of the first "half" camshaft.
• the quill shaft would then drive the square-section shaft between the two "half” camshafts, in order that the two "half" camshafts receive the correctly timed pulse sequences etc., there would be two coupled square- section shafts, the second of which would be out of phase with the first, thereby allowing for the event differences.
• Figure 5 shows another embodiment of the invention, which includes two annular cams. However, unlike the version required for the in-line six, these two annular cams 7 and 7a are intended to serve a single camshaft 13. It will be seen, that input shaft 18 is provided with a square section 2, and a follower guide 4.
• Follower I is mounted upon the square-section 2 in the usual way; i.e. it is free to reciprocate.
• follower I has an eccentric pin 6 which is located in the elongated slot situated in cranked are 12, this being fixed to, or part of, the small concentric lay camshaft 21.
• the assembly comprising cranked coupling arm 12, the second square-section 2a, follower guide 4a and internal, concentric shaft 21 is a free-running, bearing located assembly, with shaft 21 mounted within the main camshaft 13.
• a second follower l ⁇ is mounted upon square-section 2a and is provided with its own annular cam 7a, annular cam 7 being provided for follower I.
• An output eccentric pin 6a is located, in free but constant communication within the elongated slot situated in the cranked arm 12a which is fixed to, or part of, the main camshaft 13. Any rotation of shaft 18 will result in the reciprocation of both followers 1 and l a, with their effects being felt upon shaft 13.
• the two followers can be subjected to separate pulse sequence timing changes, in that the lobes present upon one annular cam can be angularly moved in relation to those of the other. Either or both can be adjustable.
• one set of lobes could, if required, be used to negate those of the other, extend those of the other, or complement, or detract effects as required.
• one annular cam could be used to generate basic advance/retard of the overall camshaft assembly, while the second annular cam is used to generate the oscillatory pulse sequence variations required in order to change event profile.
• Event profile is the main cam profile event present upon the cams responsible for operating the valves.
• the Figure 5 embodiment therefore provides extreme flexibility of operation for minimum complexity.
• FIGS 6 and 7 illustrate an embodiment in which there is a rack and pinion comprising between the input shaft and the camshaft.
• a rack 22 is formed integrally with the follower I .
• a pinion gear 24 meshes with the rack 22.
• the rack and pinion coupling of Figures 6 and 7 is able to offer extremely positive coupling between the input shaft (sprocket shaft) and the camshaft 13, in that the gear tooth engagement between rack 22 and pinion 24 ensures maximum mechanical advantage.
• the reciprocative action created by the follower I and annular cam 9 is directly transferred to the pinion.
• the pinion gear 24 is fixed to, or part of, the lay- shaft 23, this being bearing located within the elongated guide members 10 and 1 1.
• Lay-shaft 23 is also provided with a compound pinion gear 25 which, serves as a planet engaging a sun gear 26 is fixed to, or part of, the camshaft 13.
• the engagement ratio indicated i.e. gear 25 being larger than gear 26 would suggest that the oscillatory motion created in the pinion- 24 will be exaggerated.
• any suitable ratio between the rack and pinion, and/or compound pinion and camshaft sun gear can be contemplated according to design requirements.
• the four lobes of cam 9 are shown to be in the 45 ; 135 ; 225 and 315 positions, with lobe 8 at 315 , however, this is only a hypothetical layout and the positional locations can be situated at any point, and the contours of the lobes can be designed to any set of angular requirements, thereby making the pulse shape suitable for any valve event characteristics as may be required.
• annular cam carrier 7 can be either fixed or repositional, and the methods of rotating and locking can be of any suitable kind.
• a peripheral worm-wheel fixed to, or part of, the outer face of the annular carrier 7, engaged with a worm, with say, a 10° lead angle, will satisfy both requirements.
• Input shaft 18 can be a shaft connected directly to the sprocket wheel (not shown) or to any other rotational device.
• a double rack and pinion, twin annular assembly version as suggested by the single annulus version of Figures 6 and 7 could be constructed in order to produce a device similar to that illustrated by Figure 5, i.e. one section responsible for overall advance/retard, and the second section concerned with pulse generation. Both sections may be variable one against the other, or in any conflicting or compatible overlapping of function.
• AH of the devices herein described as hypothetical and variations, and combinations of their various characteristics etc, can be contemplated, however, they offer to the engine designer, a very easy method of including complete control and variation of valve timing and event profile/envelope etc.
• the mechanical components required are of basic engineering requirement, and there are no "new material" requirements.

Landscapes

• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Transmission Devices (AREA)
• Valve Device For Special Equipments (AREA)
• Valve-Gear Or Valve Arrangements (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

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Family Applications (1)

Country Status (5)

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Family Cites Families (5)

• 1985
  • 1985-08-31 GB GB858521718A patent/GB8521718D0/en active Pending
• 1986
  • 1986-08-29 GB GB08620899A patent/GB2183770A/en not_active Withdrawn
  • 1986-08-29 WO PCT/GB1986/000515 patent/WO1987001423A1/en unknown
  • 1986-08-29 AU AU63335/86A patent/AU6333586A/en not_active Abandoned
  • 1986-08-29 EP EP19860905339 patent/EP0235229A1/de not_active Withdrawn
  • 1986-08-30 CN CN198686106074A patent/CN86106074A/zh active Pending

Non-Patent Citations (1)

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