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
  • F16D3/00—Yielding couplings, i.e. with means permitting movement between the connected parts during the drive
  • F16D3/02—Yielding couplings, i.e. with means permitting movement between the connected parts during the drive adapted to specific functions
  • F16D3/10—Couplings with means for varying the angular relationship of two coaxial shafts during motion
• • 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
  • F01L1/352—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 using bevel or epicyclic gear
• • 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
  • F16H35/008—Gearings or mechanisms with other special functional features for variation of rotational phase relationship, e.g. angular relationship between input and output shaft

Definitions

• THIS INVENTION relates to a variable drive mechanism in which first and second rotatable members are coupled together for rotation at a phase relative to one another which is variable.
• variable drive mechanism in which first and second rotatable members are coupled together for rotation at a phase relative to one another which is variable, which mechanism comprises a first helical gear rotatable with the first member, a second helical gear which is rotatable with the second member and is coupled to the first helical gear to transmit rotation of the first member to the second member, and adjusting means for varying the axial regions of the helical gears which are coupled together to vary the relative phase of the rotations of the first and second members.
• variable drive mechanism in which first and second rotatable members are coupled together for rotation at a phase relative to one another which is variable, which mechanism comprises a first helical gear rotatable with one of the first and second members, a second gear which is rotatable with the other member and is coupled to the first helical gear to transmit rotation of one member to the other, and adjusting means for varying the axial region of the first helical gear coupled to the second gear to vary the relative phase of the rotations of the first and second members.
• a mechanism embodying the invention enables one shaft or component to have the timing of its rotation advanced and/or retarded in relation to another shaft or component.
• the abil ity to vary the relative timing of the rotation of components is extremely useful, especially in relation to camshaft drives as provided in internal combustion engines, for example.
• a direct drive is usually provided from the crankshaft to the camshaft by way of a chain or belt arrangement driving a fixed sprocket wheel mounted on the nose of the camshaft.
• the required 2:1 reduction in rotational speed between the camshaft and the camshaft is provided by making the camshaft sprocket wheel larger than the driving sprocket wheel on the crankshaft.
• a camshaft which can be advanced and retarded offers a means of providing considerable improvement in engine performance, both as regards power and emission control and various devices have been suggested to enable the rotation of a camshaft to be advanced or retarded.
• the known devices only provide an all or nothing adjustment in a limited range.
• a mechanism embodying the invention enables the phase of rotation of a camshaft to be fully and steplessly varied.
• Figures 1 A and 1 C are respectively a partly sectioned side elevation, a setion on line A-A and a section on line B-B illustrating a variable drive mechanism for a camshaft in accordance with a first embodiment of the invention
• Figure 2 is an axial cross-sectional view of a variable drive mechanism in accordance with a second embodiment of the invention
• Figure 3 is an axial cross-sectional view of a variable drive mechanism in accordance with a third embodiment of the invention.
• Figure is an axial cross-sectional view of a variable drive mechanism in accordance with a fourth embodiment of the invention.
• Figure I of the drawings shows in side elevation and partly sectioned a simple embodiment using two helical gears I and 2, the gear I being driven by a square section portion 4 of an input shaft 9.
• Gear I is, therefore in constant driven communication with shaft 9, with the shaft portion 4 providing drive at all times, but gear I can slide along the shaft portions 4 in a lateral fashion while still maintaining drive contact.
• Input shaft 9 and camshaft 8 are journal led in supports 10 and 12 of an engine.
• gear I is a wide gear, as compared with gear 2, it will be seen that lateral sliding (in either direction) of gear I will still retain the engaged situation between the two gears, i.e.
• gears I and 2 remain constantly engaged at a ratio of 2 : I .
• Gear I has, for example, 20 teeth and gear 2 has, for example, 40 teeth, although any required ratio can be envisaged.
• the size of a drive sprocket (not shown) mounted on the left hand or front end of the shaft 9 can be reduced, thereby allowing overall engine height, at the most important point (i.e. the extreme front end) to be reduced and allowing for considerable flexibility in the body styling of a vehicle incorporating a camshaft with the proposed drive mechanism.
• gears I and 2 are sufficient to create the required advance/retard characteristics, and left, or right hand helices may be chosen for gear I with the appropriate opposite hand provided for gear 2.
• Carrier 3 is a saddle type device which is bearing located upon shaft 9 and a parallel control shaft 7.
• the carrier has two end plates 3b and 3c which each have two circular apertures (See Figure 2c). These apertures are of similar diameter to the two shafts 9 and 7, thereby allowing free sliding movement of the carrier along the two parallel shafts.
• the plates 3b and 3c are interconnected by a cross-tie 3a.
• Carrier 3 is also provided with a section of rack gearing 5, located in this particular design on the underside of the cross-tie 3a which also serves to fix together into a single unit the two end plates 3b and 3c.
• the items 3a, 3b, 3c and 5 can be manufactured in one or more pieces to form either an assembly or a single component.
• Rack 5 is engaged with a worm pinion 6 which is fixed to, or part of, shaft 7.
• a standard pinion could be used with shaft 7 at right angles to the rack 5 - this is not shown on the drawing of Figure I .
• the lead angle of the worm pinion 6 is a so-called "locking" angle, e.g. around 10 , with the result that the rack can be driven by the worm pinion but the worm pinion cannot be rotated by the rack 5. Therefore, any rotation of shaft 7 will drive the rack 5 in either direction according to the direction of shaft rotation, and that movement is only restricted by the distance between the two end plates 3b and 3c and the worm pinion 6.
• This type of device can be provided for a complete camshaft (outlet or inlet) or any single cam, or groups of cams.
• the shaft portion 4 can be replaced by a straight spline, a groove or the like, or may be of any cross-section able to provide drive of a rotational nature between shaft 9 and gear 1.
• gear 2 might also be given sliding abilities, with control being supplied in a similar fashion to that described for gear I , so that either or both of gears I and 2 can be relocated upon their respective shafts.
• Drive for the or each control shaft (7 as an example) is supplied by any suitable drive means, e.g. an electric or hydraulic motor, the commands for such drive means coming from an overall engine management system, or some other dedicated control source. Manual control could also be used if required.
• any suitable drive means e.g. an electric or hydraulic motor, the commands for such drive means coming from an overall engine management system, or some other dedicated control source. Manual control could also be used if required.
• gear 2 is aiso capable of sliding upon shaft 8 while still retaining the ability to drive shaft 8 " via a square section portion of the shaft, then another possibility can be envisaged.
• gear 2 can be made to reciprocate in an axial fashion upon shaft 8, thereby creating an oscillatory motion for shaft 8.
• the number of oscillatory pulses is determined by the number of undulations or lobes present upon the face cam, or by the number of followers.
• This oscillatory motion can also be variable,
• the follower or roller can be mounted upon a carrier capable of concentric (or other) advance/retard, thereby allowing an advance and/or retard of the pulse sequence.
• oscillatory characteristics are included in the Figure I mechanism, they can be generated via either gear I and/or gear 2, and the basic sliding advance/retard ability can be given to either gear. Furthermore, the oscillatory ability can be included without the basic advance/retard characteristic being included, i.e. gear I , for example, could be fixed to shaft 9.
• Figure 2 shows ⁇ device capable of providing advance/retard characteristics, but does not include the 2 : I (or any other ratio) reduction as demonstrated by Figure I . However, it offers a very simple mechanism for camshaft management.
• gear I is fixed to, or part of, input shaft 9 and gear 2 is fixed to, or part of, shaft 8.
• shaft 8 is indicated as the camshaft
• shaft 9 is the shaft fixed to sprocket 14.
• Shaft 15 is a location shaft for centring the sprocket 14.
• the basic construction of the mechanism shown in Figure 2 is derived from a piston and cylinder combination, in which a cylinder 21 .provides the support and bearing location for a piston 22.
• the piston 22 is able to slide within the cylinder 21 but is not able to rotate.
• the positioning and movement of the piston 22 is provided by way of a screwed section 28 of control shaft 27 engaged within a threaded aperture 15, in much the same way as in a lathe, for example, thereby ensuring that any rotation of shaft 7 will cause piston 22 to move along the inside of cylinder 21.
• This movement along the cylinder is similar to that described in Figure I in respect of the carrier 3, and it is noted that the screw and thread arrangement herein described, can be used in the Figure I embodiment in place of the rack and worm pinion as previously described. Likewise, the rack and worm pinion could be used in the Figure 2 embodiment in place of the screw and thread arrangement.
• Ail carrier drive mechanisms are interchangeable throughout this specification.
• Carrier 23 is also engaged with gears I and 2 via four engaement lugs 25a - 25d. Lugs 25a and 25b are engaged with gear I and lugs 25c and 25d are engaged with gear 2.
• the number of lugs employed will be determined by the number of teeth present upon the two helical gears.
• Gears I and 2 are of opposite hands (i.e. have opposite helical spirals). As the two helics are of opposite hands, the side loadings are balanced and the carrier 23 is held in an unbiased state.
• the mechanism has outer casing or journal housings 10 and 1 2.
• piston and cylinder arrangement illustrated in Figure 2 can be replaced by any suitable sliding carrier arrangement, e.g. the piston could be a saddle type of device, running upon one or more flat surfaces or upon a roller bed.
• Figure 3 shows a mechanism which is similar in principle to that of Figure 2 but the method of moving the piston 22 is different.
• the two helical gears I and 2 are left and right- hand helixes, or, as in Figure 2, either of the gears is a helical component, while the other is a straight cut spur-gear.
• the internal splines 25a - 25d can be of any suitable number, i.e. one or more, and the fact that they are of such short length precludes the need for these items to be helical. They are, in fact, merely location pins.
• the carrier 23 is in Figure 3 caused to slide backwards and forwards by virtue of the fact that the cylinder or barrel 3 1 is screw threaded, and the carrier is correspondingly threaded so that it constitutes a threaded insert.
• the piston 22 has an extension 38 having an external gear face 38a which is engaged with a drive gear 37 mounted upon control shaft 7.
• the drive gear 37 is caused to rotate, thereby rotating assembly 22, 38, 38a.
• the rotation of this assembly causes piston 22 to be screwed into, or out from, barrel 31.
• the angle of the lead (or leads) of the screw-thread is sufficient to prevent any lateral 5. movement other than that instigated by gears 37 and 38a. Therefore, this is a totally locked carrier assembly, capable of repositioning to cause shaft 8 to be advanced and/or retarded in relation to shaft 9.
• the mechanism shown in Figure 3 does not therefore require a worm and worm-wheel combination to adjust and lock it.
• the length of the gear- 15 cut section 38 of the piston 22 remains in contact with gear 37 throughout the entire range of movement.
• Figure 4 shows a drive mechanism embodying the invention and having an oscillatory pulse generator section coupled with an 20 advance/retard section.
• the two sections can be advanced, and/or retarded independently of one another or in conjunction with each other.
• Carrier 43 is bearing located concentrically of the main centre axis 'x' - 'x' of the mechanism and is driven ax ⁇ aily (in either direction) by a novel 25 radial rack arrangement.
• the teeth, resembling radial fins as seen as cooling elements on air-cool engines, are engaged with a normal type spur- gear 47. This is fixed to shaft 46 and is controlled and driven by a worm and worm-wheel arrangement (not shown).
• Carrier 43 is provided with internal pins 45a - 45d and these are engaged with two gears I and 2, one of which must be helical.
• Gear 2 is not fixed to shaft 8 but is straight spline coupled, thereby allowing gear 2 to slide along shaft 8 but remain in rotational driving co ⁇ t ⁇ ct.
• gear 2 is also provided with two radial arms 48 and 49 which are provided with follower contact fingers, one of which is indicated at 50.
• face cam 53 is fixed to sleeve-shaft 54 and this in turn is fixed to, or part of, worm-wheel 55. This is engaged via a locking angle with worm 56 which is mounted upon its own control shaft 7. This allows rotation of cam 53 relative to the follower 50 and thereby advance/retard the oscillatory motions created.
• the above described mechanisms can be used to provide gradual advancing and retarding of the phase of rotation of a shaft and will not add to the noise difficulties associated with gearing when it is used in a normal way.
• each device can be contemplated, in that the carrier could be provided with two helical gears (or one helical and one straight cut spur) and the two shafts could be provided with the contact pins.
• the resultant function and performance envelope would remain the same as for the devices as described.

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

Applications Claiming Priority (2)

Publications (1)

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ID=10587902

Family Applications (1)

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• 1985
  • 1985-11-07 GB GB858527526A patent/GB8527526D0/en active Pending
• 1986
  • 1986-11-06 AU AU65492/86A patent/AU6549286A/en not_active Abandoned
  • 1986-11-06 EP EP19860906413 patent/EP0245345A1/en not_active Withdrawn
  • 1986-11-06 GB GB8626537A patent/GB2183780B/en not_active Expired
  • 1986-11-06 WO PCT/GB1986/000688 patent/WO1987003056A1/en unknown
  • 1986-11-07 CN CN198686107594A patent/CN86107594A/zh active Pending

Non-Patent Citations (1)

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