Rotary shafts – gudgeons – housings – and flexible couplings for ro – Overload release coupling – Torque transmitted via resiliently biased positive drive...
Reexamination Certificate
1998-01-13
2001-06-05
Browne, Lynne H. (Department: 3629)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Overload release coupling
Torque transmitted via resiliently biased positive drive...
C192S056100
Reexamination Certificate
active
06241613
ABSTRACT:
This invention relates to a drive arrangement for use in transmitting rotary motion of a drive shaft to the rotary part of a fuel pump.
A known type of high pressure fuel pump for use in supplying fuel to the cylinders of a compression ignition engine comprises a rotary distributor member which is rotatable within a sleeve. The distributor member includes a plurality of passages which, in use, register with ports provided in the sleeve whereby fuel is supplied at relatively low pressure to a pumping chamber, and whereby fuel from the pumping chamber is supplied, at high pressure, to the cylinders of the engine. In order to minimize leakage between the distributor member and the sleeve, the clearance between the distributor member and the sleeve is extremely small. The provision of such a small clearance increases the risk of seizure of the pump, in use, for example as a result of thermal expansion.
The distributor member is coupled to a drive shaft which drives the distributor member at a speed associated with engine speed. As the distributor member is coupled to the drive shaft, seizure of the pump results in rotation of the drive shaft terminating and may result in the drive shaft or other parts of the engine being damaged, or in the engine and fuel system requiring adjustment in order to adjust the timing of fuel delivery. In order to avoid such damage, it is known to provide an annular recess in the distributor member thus forming a relatively weak region. Upon seizure of the pump, the distributor member fractures at the weak region, thus permitting continued rotation of the drive shaft.
Clearly, such an arrangement then requires replacement of the distributor member.
According to the present invention there is provided a drive arrangement for transmitting rotary motion of a drive shaft to the rotary component of a pump, the drive arrangement comprising a resilient member carried by one of the drive shaft and the rotary component, the resilient member being engageable with a surface associated with the other of the drive shaft and the rotary component to transmit rotary motion of the drive shaft to the rotary component, the resilient member being arranged to ride out of engagement with the surface upon the application of a braking force greater than a predetermined braking force to the rotary component to permit relative rotary motion of the drive shaft and the rotary component.
The surface may be defined, in part, by a surface of a second projection carried by the said other of the drive shaft and the rotary component, the member being arranged to ride out of engagement with the second projection upon the application of a braking force greater than the predetermined braking force.
The drive arrangement may include a resilient, split tubular component arranged to extend around part of the periphery of the drive shaft and part of the rotary component, the tubular component being carried by and keyed to one of the rotary component and the drive shaft, the member being defined by a resilient first projection forming an integral part of the tubular component, the first projection extending inwardly and being arranged to engage the second projection provided on the other of the rotary component and the drive shaft which defines the said surface.
The tubular component may include a further projection of axial length greater than that of the resilient projection whereby the tubular component is keyed to the said one of the drive shaft and the rotary component. In use, the shorter axial length of the resilient projection results in the resilient projection riding over the second projection, upon seizure of the pump.
The part of the said other of the rotary component and the drive shaft around which the tubular component extends is conveniently shaped so that once the resilient projection has ridden out of engagement with the second projection, relative rotation of the drive shaft and rotary component is substantially unimpeded, the relative rotation subsequently resulting in the resilient projection returning into engagement with the second projection.
In an alternative embodiment, the resilient member takes the form of a member slidable within a radially extending bore, the member being spring biased out of the bore and being engageable with the said surface which is conveniently defined by a second projection. The bore is conveniently provided in the drive shaft, the part of the drive shaft provided with the bore being received within a recess provided in an end of the rotary component. The member is conveniently biased towards a position in which, when the member has ridden over the second projection, the member does not engage the rotary component.
In a further alternative, the resilient member may comprise a spherical member spring biased out of a bore, the surface being defined by a bore of diameter smaller than that of the spherical member within which part of the spherical member is receivable.
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patent: 08159028 (1996-06-01), None
Felton George Nicholas
Lewis Graham Rhys
Turner Richard Michael
Andrus Sceales Starke & Sawall LLP
Binda Greg
Browne Lynne H.
Lucas Industries Public Limited Company
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