Machine element or mechanism – Gearing – Nonplanetary gearing differential type
Patent
1994-09-28
1997-03-11
Marmor, Charles A.
Machine element or mechanism
Gearing
Nonplanetary gearing differential type
184 112, 184 114, 184 131, F16H 4814, F16H 5704
Patent
active
056090730
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a differential mechanism particularly but not exclusively for use in motor vehicles.
Differential mechanisms commonly used on vehicles are of the sun and planet gear type and have a well known disadvantage that when one wheel is on a slippery surface such as mud or ice and the other wheel is on a firm surface capable of providing traction, the first wheel will simply spin as it receives all the available power transmitted to the differential.
Limited slid differential mechanisms have been proposed in an attempt to overcome this problem which restrict the extent to which one wheel can spin relative to the other but such differentials are more complex and, therefore, more costly to produce.
In European patent application EP-A-0284329 there is proposed an alternative differential mechanism comprising two output cam members rotatable about an axis, with each cam member having a single annular cam surface thereon of undulating form comprising pairs of mutually inclined surfaces, and a plurality of cam followers having end surfaces engaging the cam surfaces of the output cam members, the arrangement being such that relative contra rotation of said output cam members causes the cam followers to slide axially, and an input element engaging and supporting the followers and moving the followers circumferentially relative to the output cam members.
Such a differential will hereinafter be called a differential of the type described.
It is desirable to lubricate the relatively moving surfaces within such a differential to keep wear to a minimum.
According to the invention there is provided a differential of the type described, characterised in that a component of the differential which rotates during use of the differental drives oil pump means for forcing oil into the differential.
The oil pump means may comprise scoops arranged externally on the component which rotates and connected with oil massageways through the component.
The component which rotates and which drives the oil pump means may be the input element of the differential.
In an alternative construction the oil pump means comprises an oil pump.
The oil pump may conveniently comprise a non-rotatable housing containing an impellor mounted on an outer surface of the input member.
Also according to the invention there is provided a differential of the kind described, wherein each output cam member has oil passageways formed therein.
The invention also provides a method of manufacture of a steel cam member having a cam surface thereon, wherein the whole member is case hardened and is subsequently treated by a salt bath nitrocarburizing process, and thereafter selected surfaces of said cam member are induction hardened.
Differential mechanisms in accordance with the invention will now be described by way of example with reference to the accompanying drawings in which:
FIG. 1 is a cross section through a differential mechanism in accordance with the invention taken through output cam members;
FIG. 2 is an end view of the differential of FIG. 1 shown partly broken away;
FIG. 3 is a development of cam surfaces with cam followers shown in positions therebetween;
FIG. 4 is a diagrammatic end view of a cam follower;
FIG. 5 is an enlarged section through a single output cam member and the adjacent portion of the input element as shown in FIG. 1 taken on the line V--V of FIG. 7;
FIG. 6 is an isometric view of an output cam member as shown in FIG. 5;
FIG. 7 is an end face view of the input element shown in FIG. 5 showing the oil pump means;
FIG. 8 is a section through a portion or an alternative input element with integral oil pump means;
FIG. 9 is an isometric view of the portion of the input element shown in FIG. 8;
FIG. 10 is a section through a modified form of differential;
FIG. 11 is a view on the line XI--XI of FIG. 10 showing lubrication grooving details;
FIG. 12 is a section through a portion of an alternative input element which drives an oil pump, and
FIG. 13 is a view on line XIII--XIII of FIG. 12 showing details of the oil pump housi
REFERENCES:
patent: 3796283 (1974-03-01), Raby
patent: 4018097 (1977-04-01), Ross
patent: 4312900 (1982-01-01), Simpson
patent: 4468981 (1984-09-01), Ries
patent: 5184583 (1993-02-01), Grell
patent: 5299881 (1994-04-01), Mettler-Friedli
Chippendale John P.
Spooner John
Young Alastair J.
Automotive Products plc
Germain Lee A.
Jensen Nathan O.
Marmor Charles A.
Milliken Paul E.
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