Note: Descriptions are shown in the official language in which they were submitted.
132~979
The present invention relates to a power system used for
vehicles operated generally from a sitting position, such as
small three-wheeled or four-wheeled vehicles. More
particularly, it relates to a variable speea transmission for
producing a variable speed by utilizing oil pressure, to
power systems which include a unitized combination of an
engine and drive train, and to vehicles employing such
transmission or combination. -
Fig. 1 is a perspective view of a four-wheeled vehicle
incorporating a variable speed transmission of a convent$onal
design;
Fig. 2 is a perspective view of a four-wheeled vehicle
incorporating the engine and power train according to the
present invention;
Fig. 3 is a partial cut-away view of an engine and a
trans-axle mounted on a vehicle viewed from a direction of an -
arrow III of Fig. 2; ~-
Fig. 4 is a fragmental sectional view showing the
relationship between a variable hydraulic pump and a crescent
hydraulic motor of a transmission according to the present
invention; and ~;
Fig. 5 is a sectional view taXen along the line V-V of
Fig. 3. -
Fig. 6 is a front view of a second embodiment of the
power system according to the present invention:
Fig. 7 is a rear view of the second embodiment;
,
132~979
Fig. 8 is a bottom view of the second embodiment;
~ig. 9 is a right side view of the second embodiment;
Fig. 10 is a top view of the second embodiment; and
Fig. 11 is a left side view of the second embodiment.
Most larger motor vehicles intended for use as passenger ~ -
vehicles or for performing certain work functions, such as
automobiles, motorcycles, buses, trucks, etc., are provided
with power trains which permit the vehicle to maintain a
constant velocity while the engine speed is varied to
accomplish this purpose. However, in smaller dedicated
vehicles which are intended to perform a work function, such ~ ;
as rear engine riders, lawn tractors, front mounted mowers,
etc., it is preferred that the engine :-
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1325979
maintain a constant speed while the vehicle speed
varies. This relationship is preferred because, in
such vehicles, which generally operate at a rela-
tively slow speed, the work-performing device is
connected, either directly or indirectly, to the
output end of the crankshaft of the vehicle. Optimum
performance of the work-performing device is achieved
within a certain rpm range and generally when the
power takeoff (hereinafter referred to as PTO) or
output end of the crankshaft is rotating at a rela-
tively constant speed. When terrain varies, there-
fore, a constant vehicle speed is sacrificed for a
constant engine speed. This may be accomplished by -~
some form of variable speed transmission.
In a vehicle of conventional design such as, for
example, a small four-wheeled cart or buggy as shown
in Fig. 1, an engine 10 is arranged in such a way -
that a crankshaft (output shaft) of the engine ex-
tends vertically. Power generated by the engine 10
is transmitted to a trans-axle 16 and a working appa-
ratus such as a lawn mower 18 by means of V-shaped
belts 12 and 14, respectively. A driving axle ar-
rangement (not shown) for controlling a variable
speed by utilizing oil pressure is incorporated into
the trans-axle 16, and rear wheels 19 are rotatably
mounted on both ends of the trans-axle 16.
However, in a variable speed transmission com-
prising the trans-axle 16 and the V-shaped belt 12
used in the four-wheeled buggy as shown in Fig. 1,
since the V-shaped belt 12 is twisted in its path,
the durability of the V-shaped belt 12 is reduced.
Further, in the above variable speed transmission,
since the engine 10 and the trans-axle 16 are con-
nected to each other by means of the V-shaped belt
1~, the trans-axle 16 cannot be supported floatingly
, , . -; .. . : ';
132~979
on a chassis of the vehicle and the V-shaped belt 12 tends to
become misaligned. Accordingly, it is necessary in the
above-described variable speed transmission to use a so-
called "rigid axle" in which the trans-axle 16 is rigidly
fixed to the vehicle chassis. Further, in the above-
described variable speed transmission, since a hydro-static
transmission is incorporated into the trans-axle 16
independently of the engine, there is, in many instanceæ, the
disadvantage that the temperature of the working oil in the
hydro-static trans~ission is drastically elevated.
:.
Further, in relation to such variable speed
transmission, a multiple axis trans-axle has been proposed as ~ ~
described in the Japanese Utility Model kaid-Open No. ;
87324/1984. However, in the multiple axes trans-axle, since
the trans-axle has a plurality of axes, the trans-axle itself
is of a large size, thereby requiring a large space for
accommodating the trans-axle on the vehicle.
. .' ' .
Thus, there is a need for a unitized power system for a
vehicle. Preferably, the power system is compact and
includes an engine and drive train enclosed in a common
hou~ing. A need also exists for a power system which is
floatingly supported and eliminates the use of a belt between
the engine and trans-axle. Vehicles now available also want
for a single oil tank or sump which provides oil to the
engine and/or the trans-axle as a lubricating oil and to the
transmission as an hydraulic fluid.
The present invention is directed to a variable speed
transmission for transmitting power from an - ;;
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132~979
,
output end of the crankshaft of an engine mounted ona vehicle to driven shafts arranged transversely of
the vehicle and to a combination of such engine and a
drive train which includes a transmission and a drive
train as a single unit contained within a common
housing. The combination of an engine and a drive
train is referred to herein as a power system. More
specifically, the unit includes an engine; a housing
fixedly connected to the engine body and encasing the
output shaft or output end of the crankshaft and the
driven shafts; an hydraulic pump which can be exter-
nally controlled to adjust the amount of oil
discharged therefrom by an operator and which is con- -
nected to the output end of the crankshaft and en-
cased in the housing; and a driving axle arrangement
including a hydraulic motor for converting oil pres-
sure from the hydraulic pump into driving power, a
reduction gear for reducing an output of the hy-
draulic motor, and a differential gear for transmit- -
ting the reduced output from the reduction gear to
separated shafts comprising the driven shafts extend-
ing transversely of the vehicle, which is connected
to said separated shafts and is~encased by the hous-
ing means.
With the above-mentioned con5truction, since the
hydraulic pump and the driving axle arrangement are
accommodated into the housing as a unit, there is no :
need for using a V-shaped belt for transmitting the
engine power and, even when the driving axle is
30 floatingly supported on the vehicle, there occurs no -
problem.
The unitized power systems of the present inven-
tion are expected to have widespread application in
vehicles in which a dedicated work function is per-
formed, such as off road vehicles. These vehicles
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1~597~
typically require a variable transmission speed which
permits the vehicle speed to vary within a range but
the engine speed to remain substantially constant,
thereby permitting a constant speed to a PTO. Exam-
ples of the types of vehicles in which the presentinvention is employed include front mounted mowing
machines, riding mowers, rear engine riders,~small
general purpose vehicles or carts, engine powered
lawn and garden maintenance equipment, engine powered
recreational equipment, golf carts, golf course care
equipment, lawn tractors, all terrain vehicles, and
the like.
The engine which forms an element of the claimed
invention may take the form of a number of different
embodiments, including both liquid- and air-cooled
engines. Such embodiments include those empLoying
different types of ~fuel," such as gasoline and die-
sel powered engines and continuous electric motors,
those varying in the number and arrangement of the
20 cylinders, such as single-cylinder engines, in-line, ~ -
and V-configuration multicyIinder engines, and rotary
engines, 2-cycle engines, and 4-cycle engines.
The transmission and power system of the present
invention may be used with front wheeI, rear wheel,
and four wheel drive vehicies.
In addition to those advantages of the present
invention noted above, the power systems described ~ `
herein provide a number of other features distin-
guishing them from conventional systems. In particu- -
lar, the power systems of the present invention are
easily assembled into self-contained units af a com-
pact size which may be readily installed in vehicles
such as those described above. This permits a lower
manufacturing cost of such vebicles. In addition to -
the compact size, the power systems of the present
- 5 -
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1325~7~
invention also have lower center~ of gravity which allow
increased stability on slopes of the vehicles. The vehicles
also have lower vibration levels and lower noise levels
becau6e of a single housing and the isolation of the power
system unit from the chassi~ as a rigid unit which
concentrates the mass of the unit. Furthermore, control of
dimensional tolerance is better and engines having different
sizes and power ratings may be used. Finally, the unitized
combination of engine, transmission, and trans-axle afforded
by the present invention permits the reduction of
manufacturing costs and moving parts ~i.e., fewer bearings
and shafts are required as compared to conventional systems).
The compactness of the power systems of the present
invention results from both the co~bination comprising a
unitized engine and drive train employing a common housing
and preferably by employing a hydro-static transmi~sion and
by including an hydraulic motor which surrounds the rear
axle.
Manufacturing costs may also be additionally reduced and
other advantages realized by employing a single oil source,
that is, a single oil tank or ~ump to provide oil to at least
one of the engine and the trans-axle as a lubricant and to
the oil pump and transmission a~ a hydraulic fluid. This
additionally allows for easier ~aintenance and, in some
cases, better cooling of the oil.
In one aspect the invention provides a unitized power ~
system for a small vehicle comprising: -
~ a) an engine having a crankshaft; (b) a drive train
operatively connected to said engine, said drive train
including a variable speed tran~mission including a variable
- 6 -
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132~79
hydraulic pump operatively connected to output means
as~sociated with the crankshaft of the engine and to an
hydraulic motor, and a driving axle arrangement; and (c) a .
housing enclosing said drive train and at least a portion of
S said engine, said housing comprising a lower casing portion
fixedly connected to a crankcase of the engine, a pump cover
portion for encasing said variable hydraulic pump, and an
axle housing portion for encasing said driving axle
arrangement, said portions being fixedly connected to each
other to form a unitary body.
" :
In a further aspect the invention provides an off road
vehicle comprising: ;
a vehicle body having a unitized power systemimountea
thereon comprising: . :
(a) an engine having a crankshaft; (b) a drive train
operatively connected to said engine, said drive train
including a variable speed transmission including a variable
hydraulic pump operatively connected to the output end :.
portion of the crankshaft of the engine and to an hydraulic
motor, and a driving axle arrangement; and ~c) a housing
enclosing said drive train and at least a portion of said ~:
engine, said housing comprising a lower casing portion
fixedly connected to a crankcase of the engine, a pump cover
portion for encasing said variable hydraulic pump, and an ~:
axle housing portion for encasing said driving axle
arrangement, said portions being fixedly connected to each : .
other to form a unitary body. -
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132~97~ :;
In a still further aspect the invention provides a
variable speed transmission for transmitting power from an
output end of the crankshaft of an engine mounted on a
vehicle to driven shafts arranged transversely of the
vehicle, comprising:
a housing means fixedly connected to a body of the ~ -
engine and encasing said output end of the crankshaft of the
engine and said driven ~hafts; a variable hydraulic pump
which can be adjustably controlled to ad~ust an amount of
fluid discharged therefrom by an operation external to said
pump, said variable hydraulic pump being connected to said :
output end of the crankshaft of the engine and being encased ;
by said housing means: and a driving axle arrangement `;: .
constituted by a hydraulic motor for converting hydraulic
pressure from said variable hydraulic pump into driving
power, a reduction gear for effecting a reduction in speed : -
of said hydraulic motor, a differential gear for ~ -
transmitting the reduced speed effected by said reduction
gear to separated shafts which form said driven shafts and
extend transversely of the vehicle, said driving axle ~ -
arrangement being connected to said separated shafts and ~
being encased by said housing means. : .
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1325979
The invention also provides a power system comprising:
(a) an engine having a crankshaft; (b) a drive train
operatively connected to said engine, said drive train
including a variable speed transmission operatively connected
to a driving axle arrangement: and (c) a common fluid
reservoir, operatively connected to said engine and said
drive train, for supplying fluid to said engine and to at .
least one of said driving axle arrangement and said variable
speed transmission. ~-
Further, the invention provides a unitized power system ~ :
for a small engine-powered vehicle, the engine having an
output shaft and the vehicle having a drive train with driven
shafts, comprising: a housing fixedly connected to a body of
said engine and encasing said output shaft of the engine and :~ ~
said driven shafts: a variable hydraulic pump which can be ~.
adjustably controlled to adjust an amount of fluid discharged -~
therefrom by an operation external to said pump, said :~
variable hydraulic pump being connected to said output shaft
of the engine and being encased by said housing; and a -
driving axle arrangement constituted by a hydraulic motor for
converting hydraulic pressure from said variable hydraulic ~
pump into driving power, a reduction gear for reducing said .:::
driving power from said hydraulic motor, a differential gear ~ ~
for transmitting the reduced driving power from said :.:
reduction gear to separated shafts which form said driven
shafts and extend transversely of the vehicle, said driving
axle arrangement being connected to said separated shafts and
being encased by said housing. .-
Still further, the invention provides an off road : .
vehicle comprising: a vehicle ~ody having a unitized power :
system mounted thereon, the power system including an engine
and drive train, the engine having an output shaft and the
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132~979
drive train having driven shafts, comprising: a housing
fixedly connected to a body of said engine and encasing said
output shaft of the engine and said driven shafts; (b) a-
variable hydraulic pump which can be adjustably controlled to
adjust an amount of fluid discharged therefrom by an
operation external to said pump, said variable hydraulic pump
being connected to said output shaft of the engine and being
encased by said housing; and (c) a driving axle arrangement
constituted by a hydraulic motor for converting hydraulic
lo pressure from said variable hydraulic pump into driving
power, a reduction gear for reducing said driving power from
said hydraulic motor, a differential gear for transmitting
the reduced driving power from said reduction gear to
separated shafts which form said driven shafts and extend
transversely of the vehicle, said driving axle arrangement -
being connected to said separated shafts and being encased by
said housing.
The present invention will now be explained with
reference to the drawings. In a preferred embodiment shown
in Figs. 2 to 4, the variable speed transmission according to
the present invention is adapted to a small four-wheeled
vehicle intended to perform a dedicated work function, in
this instance, mowing. However, it should be noted that the
present invention is not limited to the type of four-wheeled
vehicles illustrated, but can be adapted to any vehicle, and
particularly those in which the engine is intended to turn at
substantially a constant rate of speed while the speed of the
vehicle varies. In Fig. 2, an engine 20 is mounted on the
four-wheeled vehicle in such a way that a crankshaft or
output end of the crankshaft (not shown in Fig. 2) of ths
engine extends vertically. A trans-axle 22 is integrally
connected to the engine 20. Power generated by the engine is
- 8a -
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~32~97 ~ -
transmitted to rear wheels 24 through the trans-axle 22.
Further, the power from the engine is also transmitted to a
working apparatus such as a lawn mower 17 by the medium of a :
V-shaped belt 13.
More particularly, as shown in Fig. 3 which is a partial
cut-away view of an embodiment of the power train of the
present invention, specifically, of the engine 20 and the :.
trans-axle 22 viewed from the direction of an arrow III of . :
Fig. 2, a piston 29 is connected to the crankshaft 26 of the
engine 20 by means of a connecting rod 27. An hydraulic pump :
30 is operatively connected to output means associated with
the crankshaft 26, such as arranging the pump
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132~97~
around an output end portion 28 of the crankshaft
26. As an alternate embodiment, the hydraulic pump
may be operatively connected to the cam shaft with, -
for example, a gear located on the cam shaft engaging
a gear on the pump. The preferred hydraulic pump,
and that employed in the embodiments illustrated in
the figures, is a variable hydraulic pump. However,
other types of hydraulic pumps may be used, such as
hydraulic piston and gear G-rotor pumps. The pump 30 ~ -
is surrounded by a pump cover 34 which forms a part
of a housing 32, as will be fully described hereinbe-
low. Further, the output end portion 28 of the
crankshaft 26 is provided at its lower end with a PTO
shaft, which serves as a means to transmit rotational
motion. The PTO may take a variety of forms~and
applications, such as a universal joint, propeller
shaft, clutching mechanism (as, for example,~an elec-
tric or hydraulically actuated clutch) sprocket, and
the like or, as specifically illustrated in Figure 3,
a pulley 35, around which the V-shaped belt i3 is
entrained. Thus, the power generated by the engine
20 can be transmitted to the lawn mower 17~ ~Fig. 2)
through the medium of the output shaft portion 28,
pulley 35, and tne V-shaped belt 13.
The housing 32 comprises the above-mentioned
pump cover 34/ a lower casing 36, and an axle housing
38 which are integrally connected to each other.
More particularly, although most or all of the hous-
ing components may be formed as a~single housing
unit, because of manufacturing considerations, it is
preferred that the lower càsing 36 be connected or
fixed to a bottom surface of a crankcase 20a of the
engine 20 by means of bolts (not shown). In~addi-
tion, the pump cover 34 is connected or fixed to the
35 lower casing 36 by means of a plurality of bolts 34a, ~
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132~979
and the axle housing 38 is connected or fixed to side
surfaces of the crankcase 20a and the lower casing 36
by means of a plurality of bolts 38a.
A motor 40, preferably an hydraulic motor, is
housed within the axle housing 38. The preferred
hydraulic motor, and that employed in the embodiments
illustrated in the figures, comprises a crescent
hydraulic motor. However, other types of hydraulic ~-
motors may be used, such as hydraulic piston and gear ;
G-rotor motors. Particularly preferred are hydraulic
motors which surround the rear axle, as does the
crescent hydraulic motor illustrated. This hydraulic
motor 40 forms a part of a driving axle arrangement -
which will be fully described hereinbelow, and im~
15 parts rotational movement to each of separated axles -
or shafts 41. On outer ends of the separated shafts
41, the corresponding rear wheel tires 24, typically
having a large diameter, low pressure, and good cush-
ionin~ ability, are mounted. Further, the crescent
hydraulic motor 40 communicates with the variable
hydraulic pump 30 through the medium of working or ^ `
hydraulic oil passages 42 and 44 which are formed in -
walls o~ the lower casing 36 and the axle houslng ~:
38. Inner conduits, such as tubes or pipes, 43 are
25 arranged in the passages 42 and 44 at a junction `
between the lower casing 36 and the axle housing
38. Alternatively, the pipes 43 may be provided -
externally of and between the lower casing and axle
housing, as discussed below.
A variable speed transmission, preferably a
hydro-static transmission (referred to as HST herein-
after) as described above may be employed. Alterna-
tively, a continuously variable transmission may be
used. The preferred HST comprises an hydraulic pump
and an hydraulic motor, in this embodirnent, the
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132~79
variable hydraulic pump 30 and the crescent hydraulic
motor 40. Fig. 4 shows the construction of such
HST. Because of the arrangement of the crescent
hydraulic motoe 40 surrounding the separated axles or
shafts 41, the motor may be appropriately considered
as either a component of the HST or of the driving
axle arrangement, as discussed below.
In Fig. 4, the variable hydraulic pump 30 is
constituted by a cylinder block 46, a plurality of
ball pistons 47, and a cam ring 48 surrounding the
ball pistons. The ball pistons 47 are slidably ar-
ranged in corresponding oil chambers 46a which are
formed along the periphery of the cylinder block at
equidistant intervals and which extend radially and
outwardly of the cylinder block opening to the out-
side. The cam ring 48 which surrounds the ball pis-
tons 47 is rockably supported on a pin 47a fixed to
the pump cover 34 and lower casing 36 (Fig. 3). The
ball pistons 47 are slidably engaged by a cam surface
48a of the cam ring 48. When the cylinder block 46 ~ -
is rotated by the output shaft portion 28 of the
crankshaft 26, which is fixed to a central opening of
the cylinder block 46 by an appropriate means such as
a press fit, the ball pistons 47 are reciprocated in
the corresponding oil chambers 46a in such a way that
oil introduced into each oil chamber 46a from an
inlet conduit 30a is discharged from the chamber
through an outlet conduit 30b. To this end, the
inlet conduit 30a communicates with the oil chambers
46a by means of an arcuate passage 46b and ports 46c,
and the outlet conduit 30b communicates with the oil
chambers 46a by means of an arcuate passage 46d and
ports 46e.
An adjustment rod 49 for adjusting the amount
and direction of oil discharged from the oil chambers
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1325979 ~
46a is fixedly mounted in a recess 48b formed in a
right-hand end (Fig. 4) of the cam ring 48. By
shifting the adjustment rod 49 in a direction as
shown by an arrow A, the cam ring 48 is rocked or
rotated around the pin 47a, thereby adjusting the
degree of reciprocal movement of each ball piston 47
and, accordingly, the amount of oil discharged from
the variable hydraulic pump 30.
The outlet conduit 30b is connected to the hy-
draulic oil passage 44 (Fig. 3), and the inlet con-
duit 30a is connected to the hydraulic oil passage
42. Therefore, the pressurized oil discharged from : ;
the variable hydraulic pump 30 is supplied to the ~ -
crescent hydraulic motor 40 through the outlet con-
duit 30b and the hydraulic oil passage 44 and is
returned to the variable hydraulic pump 30 through
the hydraulic oil passage 42 and the inlet conduit
30a. Accordingly, the oil circulation system
includes the pump 30, the outlet conduit 30b, the hy-
draulic oil passage 44, the motor 40, the hydraulicoil passage 42, and the inlet conduit 30a. A suction
csnduit 51 for sucking oil from an oil tank S0 of the
engine 20 is connected to the hydraulic oil passages
44 and 42 through the medium of check valves 44a and
2S 42a, respectively.
The crescent hydraulic motor 40 incIudes an -
inner ring gear 52 fixed to one of the separated
shafts 41 (Fig. 3), an outer ring gear 53 having an
inner gearing 53a meshed with an outer gearing 52a of
30 the inner gear 52, and an arcuate partition member 54 -
for dividing an oil chamber defined by the inner
gearing 53a and the outer gearing 52a into two sepa-
rate compartments. When oiI flow occurs in the di-
rection shown by the arrows in oil passages 42 and
44, the inner ring gear 52 and the outer ring gear 53
' '' "-
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132~979
are rotated in the direction shown by an arrow B by
means of the pressurized oil supplied from the hy-
draulic oil passage 44 in a conventional manner. The
crescent hydraulic motor 40 itself can be reversed by
changing the direction of flow of the oil in the
hydraulic oil passages 44 and 42, thereby permitting
a rearward drive. This occurs when the adjustment
rod 49 is moved from a first position in which the ~
rod is staggered or askew with respect to (i.e., on ~ -
one side of) the midpoint in its path of motion to
the other side of the midpoint. Movement of the rod
49 from an outer limit toward the midpoint of its
path also causes a decreased rate of flow of the oil
and concomitant angular deceleration of the ring
gears 52, 53, and shafts 41.
The driving axle arrangement provided around the
separated shafts 41 may be explained with reference -
to Fig. 5 which is a sectional view taken along the
line V-V of Fig. 3. In Fig. 5, arranged around the
left-hand side separated shaft 41, are tbe crescent
hydraulic motor 40, a planetary gear reduction 55, a
differential gear 56, a brake 57~, and otber elements,
these elements being encased by~the axle housing 38.
The partition member 54 of the Crescent hy-
25 draulic motor 40 is ~ixed to a side aover 58 forming ~ -
a part of the axle housing 38 by me~ans of bolts 54a.
Fur~her, the partition member 54 is integral with a
motor housing 59 connected to the axle housing 38.
The inner ring gear 52 of the crescent hydraulic
30 motor 40 is connected, by a spllne connectian, to a -
tubular output shaft 60 arranged around and spaced
apart from the separated shaft 41. On the right-hand
end (Fig. 5) of the tubular output shaft 60, there is ~ -
provided a sun gear 6I which engages a planetary gear
35 62 of the planetary gear reduction 55. The planetary -~
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132~979
gear 62 is also engaged, at its outer portion, by a
ring gear 63 fixed to the axle housing 38 and is sup-
ported by a carrier 64 connected to a tubular shaft
65 by a spline connection.
A sun gear 66 is formed on the right-hand end of ;
the tubular shaft 65, which sun gear 66 is engaged by
a planetary gear 67. The planetary gear 67 is also
engaged, at its outer portion, by a ring gear 68
fixed to the axle housing 38 and is supported by a
carrier 69. The carrier 69 is in slidable contact
with the carrier 64, between which a lubricant oil
passage 69a is formed.
The carrier 69 is integral with a differential
case 70 into which a center pin 71, differential
pinions 72 mounted on the center pin, and differen-
tial side-gears 73 meshed with the differential pin-
ions are accommodated. The left-hand and right-hand
side-gears 73 are connected to the corresponding
separated shafts 41 by spline connections, respec- `
tivelY-
With the above-mentioned construction, a driving
power generated by the crescent hydraulic motor 40 :-
can be decreased or decelerated by the planetary gear
reduction 55 and then be transmitt~d to the separated
shafts 41 (on which the rear wheels 24 arè mounted)
by means of the differential gear 56.
A brake disc 74 is arranged around the left-hand
end portion of the tubular output shaft 60 and is
connected thereto by means of a spline connection. A
30 brake pad 75 is positioned to face the right side ~ -
surface of the brake disc 74. On the left side of ~-~
the brake disc 74, there is provided a push rod 77 -~
having a brake pad 76 in such a way that the brake
pad 76 faces the left side surface of the brake disc.
When the push rod 77 is urged in a direction shown by
' ~ ,.
- 14 - :-
132~979
an arrow C, a braking force is generated to stop the
rotational movement of the separated shafts 41. This
brake arrangement may be employed for dynamic braking
to slow the vehicle or as a parking brake. Thus,
alternate means are provided to slow the vehicle,
either with the braking arrangement just described or
by adjusting the variable hydraulic pump 30 with the
rod 49.
The separated shafts 41 are rotatably mounted at
their outer ends on the axle housing 38 through the
medium of bearings 78. Annular elastic (rubber)
insulators 80 (only one of which is partially shown
in Fig. 5~ are positioned in corresponding annular
grooves 79 formed in the axle housing 38. Further,
the insulators 80 are supported by side frames 81
which form a part of the vehicle chassis. Therefore,
the axle housing can be floatingly supported on the
side frames 81 by the shock absorbing elasticity of
the elastic insulators 80.
The operation of the variable speed transmission
according to the present invention may be explained
with reference to Fig. 3. With the above-mentioned ~ ~-
construction, as shown in Fig. 3, becau9e the axle
housing 38, rotatably supporting the separated shafts
25 41, is fixedly connected to the lower casing 36 and -
to the crankcase 20a, and since the pump cover 34
encasing the variable hydraulic pump 30 is also fix-
edly connected to the lower casing 36, even when the
axle housing 38 is floatingly supported by the elas-
tic insulators 80 (Fig. 5) on the vehicle chassis,
the engine 20 and the variable hydraulic pump 30 can
be moved together with the axle housing 38 as a unit. -
Therefore, according to the present invention,
there is no need for inclusion of a V-shaped belt 12
for transmitting the power from the engine 10 to the
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132~79 ~ -
trans-axle 16 as in the case of the transmission
shown in Fig. l; on the contrary, in the present ~
invention, the power generated by the engine 20 is -
converted into hydraulic pressure by means of the
variable hydraulic pump 30, and the hydraulic pres-
sure is transmitted, through the hydraulic oil pas-
sages 42, 44, to the crescent hydraulic motor 40
(Fig. 4) and is converted into driving power by the
crescent hydraulic motor 40. The driving power from i
the crescent hydraulic motor 40 is decreased or de-
celerated by the planetary gear reduction 55 and then
transmitted to the separated shafts 41 through the
medium of the differential gear 56.- -
The driving axle arrangement constituted by the
15 crescent hydraulic motor 40, the planetary gear ~ --
reduction 55, the differential gear 56, the brake 57,
and the like is accommodated by the axle housing as a
unit, thus making the axle housing 38 compact.
Furthermore, as shown in Fig. 4, the working oil
or hydraulic fluid circulating between the variable
hydraulic pump 30 and the crescent hydraulic;motor 40
may be a portion of the lubricating oil used to ~ -
lubricate the engine and/or the driving axle arrange~
ment which is contained or reserved in the oil tank
or sump 50. Thus, heat due to f~iction generated by
the crescent hydraulic motor 40 is cooled by the oil
which is transferred to the oil tank 50 having an `-
excellent radiating ability. This prevents overheat-
ing of the working oil for the variable hydraulic
pump 30 and the crescent hydraulic moto~ 40.
In addition to using the common sump to provide -~
lubricating oil to the engine and/or the driving axle ~-
arrangement and to supply oil as an hydraulic fluid
to an hydraulic system to operate the hydraulic pump
and hydraulic motor, the sump may be included in a
.. . .
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132~979
larger hydraulic system to activate mechanisms, such
as lift cylinders to operate mechanical devices.
Examples of such devices include post-hole diggers,
log splitters, and the like.
The viscosity of the oil used with the variable
hydraulic pump 30 and the crescent hydraulic motor 40
is preferred to be higher than what may be required
for the lubricating oil for the engine 20. Prefer-
ably, in the variable speed transmission according to
the present invention, the so-called "multi-grade
oil" having a wide viscosity range is used as the
lubricating oil for the engine 20, and this lubricat-
ing oil is also used as the working oil for the vari-
able hydraulic pump 30 and the crescent hydraulic
motor 40.
It should be noted that the present invention is
not limited to the embodiment illustrated and -
described above. For example, in place of the embod- -
iment of Fig. 3 wherein the axle housing 38 is fix-
20 edly connected to the lower casing 36 and the crank- ~-
case 20a by means of the bolts 38a, the axle housing
38 can be separated from the lower casing 36 by
connesting them by means of any flexible hydraulic
hose or rigid tubing (not shown) thus providing the
25 working oil passages ~44, 42). In this case, the ~ -
mass of the axle housing 38 is supported by the elas- -~
tic insulators 80 (Fig. 5) and, accordingly, the
total mass supported by a spring force is decreased,
and the vibration of the engine is not transmitted to
30 the axle housing. ~
~nlike the first embodiment of the present in- `
vention illustrated in Figures 2 to 5, which is a
rear axle or rear wheel-powered device and the power -
system employed therefor, the vehicle and a second
embodiment of the power system illustrated in Figures
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~ . . . . . . ... .. .. .. .. .. .. ... . . .. . . .
132~979
6 to 11 are intended primarily for use in a front
axle or front wheel-powered vehicle. Other than the
orientation of the power system of Figures 6 to 11,
and several other variants, this embodiment is simi-
lar to that illustrated in Figures 3 to 5. Likereference numerals are employed in describing the
elements of the second embodiment which are similar
to those of the first embodiment of Figures 2 to 5.
The description below is directed to those features
either not shown in Figures 2 to 5 or which are dif-
ferent from the first embodiment.
Figure 6 illustrates a front view of the power
system for a front mounted mower which includes an
air-cooled engine and drive train. Rather than ~ -
employing the internal oil passages, pipes, and con-
duits of the first embodiment of Figures 2 to 5, the
second embodiment employs external conduits 130a and
130b to transfer hydraulic fluid between the variable
hydraulic pump 30 and the crescent hydraulic motor
40. As best illustrated in Figures 8, 9, 10, and 11,
illustrating respectively a bottom view, right side
view, top view, and left side view of the unitized
power system, lubricating oil, serving as an hy-
draulic fluid, is transferred between the variable
hydraulic pump cover 34 or pump housing 197 and a
motor housing 59. To introduce lubricating oil/ -
hydraulic fluid to the power system, an oil filler
tube 186 and oil filler tube cap 187 are provided. -
To determine the volume of oil in the system, a dip-
stick (not shown) is affixed to the inside of the oil
filler tube cap. To remove oil from the system an
oil drain plug 188 is provided in the bottom of the
axle housing 38 (Figures 6 and 8). To transfer
vapo~s between the engine crankcase 20a and the axle
housing 38, a conduit, such as rubber tubing, 189 is
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132~979
encased by the pump cover 34 which is a part of the
housing 32; the driving axle arrangement, which is ::
constituted by the crescent hydraulic motor 40 for .
converting the oil pressure from the variable hy- .
5 draulic pump 30 into driving power, the planetary
gear reduction 55 for decreasing or reducing the
output of the hydraulic motor 40, and the differen- .:
tial gear 56 for transmitting the reduced driving .
power from the gear reduction 55 to the separated
shafts 41 extending transversely of the vehicle,
connected to said separated shafts and encased by the
axle housing 38 which is also a part of the housing .
32; and the working oil passages 42, 44 for communi-
cating the variable hydraulic pump 30 with the cres-
15 cent hydraulic motor 40, which are formed in the wall ~ :
of the lower casing 36 which is also a part of the ~:
housing 32. : -
With the construction as mentioned above, since ~.
the axle housing 38 is fixedly connected to the lower :~ -
casing 36 and to the crankcase 20a and since the pump
cover 34 encasing the variable hydraulic pump 30 is
also fixedly connected to the lower casing 36, even .
when the axle housing 38 is floatingly supported by : .:
the elastic insulators ~Fig. 5), the engine 20 and
the variable hydraulic pump 30 can be moved together
with the axle housing 38 in a body.
Accordingly, in the present invention, there is
no need for providing the V-shaped belt 12 for trans-
mitting the power from the engine 10 to the trans-
30 axle 16 as in the case of the transmission shown in - ~:
Fig. l; on the contrary, according to the present
invention, the power from the engine 20 can be con-
verted into hydraulic pressure by the variable
hydraulic pump 30. The hydraulic pressure can be
transmitted, through the working oil passages 42 and
', ~'
- 20 - ~
'.:
::
~ . - . . -. ~ .. , . .. . ; - -.. , - - . - .. . .. . ~ .
~32~97~ :~
44, to the crescent hydraulic motor 40 (Fig. 5) wherein the .
hydraulic pressure can be converted into driving power or
driving force. The driving power from the crescent hydraulic :
motor 40 can be decreased or reduced by the planetary gear : ::
reduction 55 and then be transmitted to the separated shafts
41 through the differential gear 56. ~-
~ ::
Further, since the driving axle arrangement constituted
by the hydraulic motor 40, the planetary gear reduction 55,
the differential gear 56, the brake 57, and the like is
accommodated into the axle housing 38 as a unit, the axle -
housing 38 itself can be compact, and the driving axle
arrangement can easily be mounted on a small-sized vehicle
such as that shown in Fig. 2. :~-
~ .
3~
- 21 - ::
: .
:~'. ,.
. ~ . ,.
- -
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