Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1'[~7~970
BACKGROUND OF THE INVENTION
1. Field of the Invention
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This invention relates to rotary drive assemblies
and in particular to means for lubricating such assemblies
having clutch and brake packs.
2. Description of the Prior Art
In one form of rotative drive assembly, a brake pack
and a clutch pack are provided for controlling the delivery of
driving power to a final drive, such as the final drive of the
wheeled or track-type vehicle. In such drive assemblies,
lubricating oil is provided to the clutch pack or brakes for
both eooling and lubricating the plates thereof when engaged.
The clutch and brake packs may be selectively operated to effect
a steering operation as by controlling the driving and braking
of opposite sides of the vehicle propulsion means.
A number of different prior art United States Letters
Patent disclose means for cooling clutches and the like in such
rotative drive assemblies. Illustratively, in United States
Letters Patent 3,351,169, of Ronald M. McIndoe issued Nov. 7,
1967, a eontrol sy~stem for hydraulically actuated friction
clutches is disclosed wherein a cooling flow of lubricant is
delivered to the clutch disks during partial engagement but
not during disengagement thereof. A manual ~lutch pedal is
connected through a linkage to suitable valve means of a
hydraulically actuated clutch control to control the supply of
fluid to the friction surfaces~
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The valve means includes a first portion defining a pressure
regulator for modulating the pressure of and controlling the
~low of clutch-engaging fluid, and a second portion for con-
trolling the flow of clutch cooling fluid. The modulation of
the valve permits the operator to obtain a desired degree of
clutch engagement. The system utilizes a relatively sophisti-
cated external valving means for effecting the desired control.
Another example of hydrodynamic and friction cou-
pling is shown in United States Letters Patent 3,547,235 of
Hellmut Weinrich. As disclosed therein, oil circulation is
effected during a braking operation to bring about a cooling
of the braking discs. In effect, a fottinger circuit is formed.
United States Letters Patent 3,773,157 of Franklin O.
Koch, Jr. et al, discloses a clutch with coolant cut-off valve
arranged to divert fluid from the friction means during disen-
gagement thereof to eliminate viscous drag. Upon disengage-
ment of the clutch assembly therein, a housing is moved while
the valve is held in position by means of a control rod. Move-
ment of the housing opens flow passages for providing free
20 flow of fluid from the pressure chamber directly to the sump -
to provide a sharp cut-off of fluid supply to the clutch disc
assembly. The result is that the space between the discs is
free of oil, thereby eliminating this viscous drag. A separate
diverter valve is provided in a cylindrical bore of the struc-
ture to provide the desired control.
SUMMARY OF THE INVENTION
The present invention comprehends a rotative drive
assembly having a clutch pack provided with a selectively
movable clutch piston means for selectively engaging the clutch,
a brake pack provided with a selectively movable brake piston
means for selectively actuating the brake, and a source of
pressurized lubricating oil, the improvement comprising
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conducting means for conducting lubricant oil from the source
to said clutch pack and brake pack including flow control
means for selectively causing concurrent delivery of the lubri-
cating oil therethrough to the clutch pack and brake pack with
the delivery to the clutch pack being controlled automatically
as an incident of movement of the piston of the brake pack~
said conducting means being arranged to provide selectively to
the brake pack a large flow of said oil for concurrently cool-
ing and lubricating the brake pack when the brake is actuated
and a decreased flow for lubricating the brake pack when the
brake is not actuated, said conducting means substantially
reducing the flow of said oil to said clutch pack solely by
diverting a substantial portion of the flow from the clutch
pack to the brake pack as a result of the actuation of said
brake pack.
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More specifically, the clutch pack and brake pack
are operated by piston means associated respectively there-
with whereby movement of the piston means is utilized for
effecting the desired control of the delivery of lubricating
oil to the clutch and/or brake pack.
The control means may be arranged to provide selec-
tively to the clutch pack a large flow of lubricant for con-
currently cooling and lubricating the clutch pack when engaged,
and a small flow for only lubricating the clutch pack when dis-
engaged.
The control means may further comprise means forproviding selectively to the brake pack a large flow for con-
currently cooling and lubricating the brake pack when engaged,
and a small flow for only lubricating the brake pack when dis-
engaged.
A carrier may be provided extending between the brake
pack and clutch pack and may define passage means forming a
portion of the flow conducting means.
In the illustrated embodiment, the brake piston means
includes a brake piston and a retainer movably carrying the
brake piston with the lubricant conducting means comprising
passage means extending through the retainer and passage means
extending through the brake piston selectively communicable
with the retainer passage means.
In the illustrated embodiment, the clutch piston
means may include a clutch piston and a retainer movably carry-
ing the clutch piston with the conducting means comprising
passage means through the clutch piston retainer and with the
passage means extending through the clutch piston being selec-
tively communicable with the clutch retainer passage means.
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The control means may direct at least a preselected
minimum flow of lubricant to the clutch pack and/or brake pack
at all times during rotation of the drive assembly.
The flow conducting means may include flow restricting
means for restricting lubricating oil flow to the brake pack
when the brake is not actuated.
The conducting means may include means for directing
a major portion of the lubricant oil flow away from the clutch
pack when the clutch pack is not engaged.
Thus, the drive assembly structure of the present in-
vention is extremely simple and economical of construc~ion while
yet providing the highly desirable features as discussed above.
BRIEF DESCRIPTION OF THE DRAWING
Other features and advantages of the invention will
be apparent from the following description taken in connection
with the accompanying drawing wherein: ~-
FIGURE 1 is a fragmentary diametric section of a rota-
tive drive assembly having improved lubricating and cooling
means embodying the invention;
FIGURE 2 is a fragmentary sectional view taken sub-
stantially along the line 2-2 of Figure l;
FIGURE 3 is a fragmentary diametric section of the
assembly with the clutch released;
FIGURE 4 is a fragmentary enlarged diametric section
of the assembly with the brake released;
FIGURE 5 is a fragmentary diametric section of the
assembly with the brake engaged; and
FIGURE 6 is a fragmentary diametric section of the
assembly illustrating the flow of coolant lubricant to the
clutch and brake during operation of the drive assembly.
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7~970
DESCRIPTION OF THE PREFERRED EMBODIMENT
In the exemplary embodiment of the invention as dis-
closed in the drawing, a rotative drive assembly generally
designated 10 is shown to comprise a brake pack generally desig- ,
nated 11, a clutch pack generally designated 12, and a final
drive generally designated 13. An input drive shaft 14 is
selectively connected to the final drive shaft 15 through the ,-
drive assembly so as to provide a steering brake control of a
vehicle (not shown) in which the drive assembly is provided.
The present invention is concerned with the problem
of providing cooling and lubrication of the brake and clutch
packs and comprehends an improved means for effecting the same.
More specifically, as shown in Figure 4, brake pack
11 includes an outer housing 16. As illustrated in Figure 2,
the housing 16 is provided with three lubricating oil delivery
passages 17, 18 and 19. Each of these passages is connected
to a suitable source (not shown) of pressurized coolant lubri-
cating oil suitable to cool and lubricate the brake and clutch
pack,s, respectively. Each of the flow passages is closed at
its lower end by a suitable check valve 20, as illustrated in
Figure 4 in connection with flow passage 18. Flow passage 18
communicates with a passage 21 provided in a retainer 22 slidably
carrying a brake piston 23 of the brake pack 11. Piston 23 is
biased by a Belleville spring 24 compressed between the brake
housing 16 and the piston 23.
Passage 21 in retainer 22 is provided with an outlet 25
opening to a chamber 26 inwardly of the piston 23 so that when
pressurized oil is delivered therethrough to chamber 26, the bias
of spring,24 is overcome so as to release the friction brake 27.
Similarly, as shown in Figure 3, the clutch 28 of
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clutch pack 12 is operated by a clutch piston 29 under the
biasing action of a Belleville spring 30. Piston 29 is carried
on a retainer 31.
As further shown in Figure 3, extending between brake
pack 11 and clutch pack 12 is a two-piece carrier generally
designat~d 32 having a first portion 33 splined to the drive
shaft 15 and to the clutch 28. Carrier portion 33 is provided
with a first bearing 34 for inwardly journaling the brake piston
retainer 22. A second portion 35 of the carrier is provided
with a bearing 36 for inwardly journaling the retainer 31 of
the clutch pack.
As shown in Figure 3, brake piston retainer 22 is pro-
vided with a passage 37 which opens to a passage 38 in carrier
portion 33 for conducting pressurized oil from brake housing
passage 19. Carrier passage 38 communicates with a passage
39 in carrier portion 35, which, in turn, communicates with
a passage 40 in clutch piston retainer 31 to provide pressurized
oil to chamber 41 of the clutch pack for urging the clutch piston
29 to the left, as seen in Figure 3, against the bias of spring
30 and thereby disengaging the clutch 28.
Thus, by suitably controlling the delivery of pressur-
ized fluid to the chambers 26 and 41 of the brake pack and clutch
pack, respectively, from the delivery passages 18 and 19, respec-
tively, selective operation of the brake and clutch may be
effected in the rotative drive assembly 10.
Cooling lubricant oil is delivered to the brake and
clutch packs from the delivery passage 17, as shown in Figure 2.
As further shown in Figure 6, the coolant lubricant is delivered
from passage 17 to a passage 42 in brake piston retainer 22 and
30 from passage 42 to a passage 43 in an annular sleeve 44 extending
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concentrically about carrier portion 33.
The coolant lubricant is delivered from passage 43
to a passage 45 in carrier portion 33, a passage 46 in carrier
portion 35 communicating with passage Ll5, a passage 47 in a
sleeve 48 extending concentrically about carrier portion 35,
and a passage 49 in clutch piston retainer 31 to the clutch
pack 12.
As further shown in Figure 5, the coolant lubricant
is delivered from passage 42 to an annular recess 50 in piston
o 23. Depending on the disposition of piston 23, recess 50 may
be in selective communication with an annular recess 51 in
brake piston retainer 22, which is in communication with a pas-
sage 52 extending through the retainer 22 for delivering the
coolant lubricant to the brake pack 11. More specifically,
~ when the brake piston is urged to the right against the biasing
f action of spring 24 by the delivery of pressurized fluid to
chamber 26, as shown in Figure 4, piston recess 50 is displaced
to the right sufficiently to provide only limited delivery of
I coolant lubricant to the recess 51 and thereby provide a
f 20 limited delivery of lubricant to the brake pack. When the brake
~ is applied by the removal of pressure from chamber 26, the pis-
'~ ton 23 moves to the left, as seen in Figure 5, to place the
recess 51 in full communication with the piston recess 50,
thereby permitting a relatively unrestricted flow of coolant
1 lubricant to the brake pack and thereby decreasing the delivery
i f coolant lubricant from passage 42 to the clutch pack, while
yet maintaining a continued small delivery of lubricant thereto.
~ When the brake is engaged, coolant flow to the clutch is de-
j creased because coolant flow through 51 and 52 to the brake
30 causes a pressure drop in coolant passages 45, 46 and 49 to
the clutch. Ho~ever, as shown in Figures 5 and 6, there is
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always some coolant flow to the clutch via passages 17, 43, ~-
45, 46, 47 and 49, and this flow is effectively not varied
by operation of the clutch.
Thus, the selective movement of the brake piston 23
automatically controls the delivery of the coolant lubricant
to both the brake pack and clutch pack so as to provide in the
drive assembly 10 a large volume delivery of the coolant lubri- `
cant to the clutch pack when the clutch is engaged and to the
brake pack when the brake is actuated. When the brake is en-
gaged, the coolant flow to the brake pack is increased and the
coolant flow to the clutch pack is concurrently automatically
decreased. When the brake is released, coolant flow to the
brake pack is decreased, and coolant flow to the clutch pack
is increased. Operation and movement of the clutch piston
does not effectively vary the coolant flow to either the clutch
pack or brake pack.
Thus, the present invention eliminates the need for
costly valves and the like and utilizes the elements of the
rotative drive assembly in a novel and simple manner to pro-
vide the highly desirably improved lubricant flow control.
The passages in the different elements of the driveassembly providing the lubricant flow paths discussed above
may be provided by simple drilling operations and, thus, the
improved lubricant control system is extremely simple and
economical of construction.
The foregoing disclosure of specific embodiments is
illustrative of the broad inventive concepts comprehended by
the invention.
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