CA1325979C - Unitized power system and vehicles employing same - Google Patents
Unitized power system and vehicles employing sameInfo
- Publication number
- CA1325979C CA1325979C CA 592023 CA592023A CA1325979C CA 1325979 C CA1325979 C CA 1325979C CA 592023 CA592023 CA 592023 CA 592023 A CA592023 A CA 592023A CA 1325979 C CA1325979 C CA 1325979C
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- CA
- Canada
- Prior art keywords
- engine
- hydraulic motor
- housing
- variable
- hydraulic pump
- Prior art date
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Abstract
Abstract:
A unitized power system and an off road vehicle including such power system are provided comprising an engine having a crankshift; a drive train opera-tively connected to the engine, the drive train including a variable speed transmission and a driving axle arrangement; and a housing enclosing the drive train and at least a portion of the engine. The variable speed transmission transmits power from the output end of the crankshaft of the engine to driven shafts of the vehicle.
Preferably, the unitary housing is provided for encasing all of the output end of the crankshaft of the engine. The variable speed transmission prefer-ably also includes a variable hydraulic pump for converting the engine power into hydraulic pressure, a crescent hydraulic motor for converting the hydraulic pressure into driving power, a reduction gear for reducing the driving power, a differential gear for transmitting the reduced driving power to the driven shafts, and the driven shafts. The hous-ing includes a lower casing portion fixed to a crankcase of the engine, a pump cover portion for encasing the variable hydraulic pump, and an axle housing portion for encasing the crescent hydraulic motor, reduction gear, and differential gear, the portions being fixedly connected to each other to form a unitary body.
A unitized power system and an off road vehicle including such power system are provided comprising an engine having a crankshift; a drive train opera-tively connected to the engine, the drive train including a variable speed transmission and a driving axle arrangement; and a housing enclosing the drive train and at least a portion of the engine. The variable speed transmission transmits power from the output end of the crankshaft of the engine to driven shafts of the vehicle.
Preferably, the unitary housing is provided for encasing all of the output end of the crankshaft of the engine. The variable speed transmission prefer-ably also includes a variable hydraulic pump for converting the engine power into hydraulic pressure, a crescent hydraulic motor for converting the hydraulic pressure into driving power, a reduction gear for reducing the driving power, a differential gear for transmitting the reduced driving power to the driven shafts, and the driven shafts. The hous-ing includes a lower casing portion fixed to a crankcase of the engine, a pump cover portion for encasing the variable hydraulic pump, and an axle housing portion for encasing the crescent hydraulic motor, reduction gear, and differential gear, the portions being fixedly connected to each other to form a unitary body.
Description
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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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.
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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.
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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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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 ,~
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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 ~,P' - .
~ . ' 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.
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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. -- 7- :
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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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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 -A
~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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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 - 10 - ,, . : - - ., : .. , .. . ~ . .. , :,.. - . - - . , : -: , ~ .~
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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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 ' '' "-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 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 .. . .
:, -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 ~ . . . . . . ... .. .. .. .. .. .. ... . . .. . . .
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 - :. . - .. .. . . . . . .
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 - ~
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~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. :~-~ .
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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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 - ;;
: ~:
:: :: ::
X ' ~`:
:: :::
-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 ''' ''. :
.
~.
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 ,~
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 ~,P' - .
~ . ' 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. -- 7- :
., ,. :, : .
.. :
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. : .
,' , .' : . ' .
, :
~ - 7 a ~
~. '"
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 . ':
- 8 - :
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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 -A
~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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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, ~
' ,', _ g - .,.
.:
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 - 10 - ,, . : - - ., : .. , .. . ~ . .. , :,.. - . - - . , : -: , ~ .~
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 '' '.~,:`
. ":
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 ' '' "-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 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 .. . .
:, -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 ~ . . . . . . ... .. .. .. .. .. .. ... . . .. . . .
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 - :. . - .. .. . . . . . .
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 - ::
: .
:~'. ,.
. ~ . ,.
- -': ~'' '
- 21 - ::
: .
:~'. ,.
. ~ . ,.
- -': ~'' '
Claims (46)
1. 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 transmission including a variable hydraulic pump operatively connected to output means associated 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 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.
(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 output means associated 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 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.
2. A unitized power system according to claim 1 wherein said variable speed transmission comprises a hydro-static transmission.
3. A unitized power system according to claim 1 wherein said variable speed transmission comprises a continuously variable transmission.
4. A unitized power system according to claim 1 wherein said output means comprises an output end portion of the crankshaft.
5. A unitized power system according to claim 1 wherein said output means comprises the camshaft.
6. A unitized power system according to claim 1 wherein said hydraulic motor comprises a crescent hydraulic motor.
7. A unitized power system according to claim 1 wherein said variable hydraulic pump is adjustable to control the discharge of a varying amount of hydraulic fluid to said hydraulic motor.
8. A unitized power system according to claim 1 wherein said driving axle arrangement comprises:
a reduction gear operatively associated with said hydraulic motor, driven shafts comprising separated shafts extending transversely of the vehicle, and a differential gear located intermediate and operatively associated with said reduction gear and said separated shafts.
a reduction gear operatively associated with said hydraulic motor, driven shafts comprising separated shafts extending transversely of the vehicle, and a differential gear located intermediate and operatively associated with said reduction gear and said separated shafts.
9. A unitized power system according to claim 8 wherein said hydraulic motor is a crescent hydraulic motor and said reduction gear is a planetary reduction gear, and wherein said driving axle arrangement comprises said differential gear operatively connected to said separated shafts, and said crescent hydraulic motor and said planetary reduction gear are both arranged coaxial with respect to said separated shafts.
10. A unitized power system according to claim 8 further including a vehicular braking system operatively associated with said driven shafts.
11. A unitized power system according to claim 1 wherein said variable hydraulic pump comprises a substantially cylindrical cylinder block having a plurality of radially extending oil chambers and being mounted on an intermediate portion of said output end portion of the crankshaft for rotation therewith, a plurality of ball pistons slidably arranged in the corresponding oil chambers and shiftable radially of said cylinder block, and a cam ring which can be adjusted by rocking it around said output shaft from outside to adjust the degree of movement of said ball pistons in the corresponding oil chambers, thereby adjusting an amount of working oil discharged from said variable hydraulic pump.
12. A unitized power system according to claim 1 further comprising a common sump for providing lubricating oil to at least one of said engine and said driving axle arrangement and also to supply oil as a hydraulic fluid to said hydraulic pump and to said hydraulic motor.
13. A unitized power system according to claim 1 wherein said housing includes a motor housing.
14. A unitized power system according to claim 1 further comprising oil passages operatively communicating within said housing between said hydraulic pump and said hydraulic motor.
15. A unitized power system according to claim 1 further comprising oil passage conduits external of said housing for communicating between said hydraulic pump and said hydraulic motor.
16. A unitized power system according to claim 1, further comprising rubber insulators operatively connected to said housing and adapted to be operatively connected to a chassis of a vehicle.
17. A unitized power system according to claim 1 wherein said engine and said drive train have a common fluid reservoir.
18. An off road vehicle comprising:
a vehicle body having a unitized power system mounted 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.
a vehicle body having a unitized power system mounted 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.
19. An off road vehicle according to claim 18 wherein said transmission is a hydro-static transmission.
20. An off road vehicle according to claim 18 wherein said variable speed transmission comprises a continuously variable transmission.
21. An off road vehicle according to claim 18 wherein said output means comprises an output end portion of the crankshaft.
22. An off road vehicle according to claim 18 wherein said output means comprises the camshaft.
23. An off road vehicle according to claim 18 wherein said hydraulic motor is a crescent hydraulic motor.
24. An off road vehicle according to claim 18 wherein said variable hydraulic pump is adjustable to control the discharge of a varying amount of hydraulic fluid to said hydraulic motor.
25. An off road vehicle according to claim 18 wherein said driving axle arrangement comprises:
a reduction gear operatively associated with said hydraulic motor, driven shafts comprising separated shafts extending transversely of the vehicle, and a differential gear located intermediate and operatively associated with said reduction gear and said separated shaft.
a reduction gear operatively associated with said hydraulic motor, driven shafts comprising separated shafts extending transversely of the vehicle, and a differential gear located intermediate and operatively associated with said reduction gear and said separated shaft.
26. An off road vehicle according to claim 25 wherein said hydraulic motor is a crescent hydraulic motor and said reduction hear is a planetary reduction gear, and wherein said driving axle arrangement is constituted by the differential gear operatively connected to said separated shafts, and said crescent hydraulic motor and said planetary reduction gear are both arranged coaxial with respect to said separated shafts.
27. An off road vehicle according to claim 32 further including a vehicular braking system operatively associated with said driven shafts.
28. An off road vehicle according to claim 18 wherein said variable hydraulic pump comprises a substantially cylindrical cylinder block having a plurality of radially extending oil chambers and being mounted on an intermediate portion of said output end portion of the crankshaft for rotation therewith, a plurality of ball pistons slidably arranged in the corresponding oil chambers and shiftable radially of said cylinder block, and a cam ring which can be adjusted by rocking it around said output shaft from outside to adjust the degree of movement of said ball pistons in the corresponding oil chambers, thereby adjusting an amount of working oil discharged from said variable hydraulic pump.
29. An off road vehicle according to claim 18 wherein a common sump is provided as a source of lubricating oil for at least one of said engine and said driving axle arrangement and is also used to supply oil as a hydraulic fluid to said hydraulic pump and to said hydraulic motor.
30. An off road vehicle according to claim 18 wherein said housing includes a motor housing.
31. An off road vehicle according to claim 18 further comprising oil passages operatively communicating within said housing between said hydraulic pump and said hydraulic motor.
32. An off road vehicle according to claim 18 further comprising oil passage conduits external of said housing for communicating between said hydraulic pump and said hydraulic motor.
33. An off road vehicle according to claim 18 further comprising rubber insulators operatively connected to said housing and operatively connected to a chassis of the vehicle.
34. An off road vehicle according to claim 18 wherein said engine and said drive train have a common fluid reservoir.
35. 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 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 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.
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 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 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.
36. A variable speed transmission according to claim 35 wherein said variable hydraulic pump comprises a substantially cylindrical cylinder block having a plurality of radially extending oil chambers and being mounted on an intermediate portion of said output end portion of the crankshaft for rotation therewith, a plurality of ball pistons slidably arranged in the corresponding oil chambers and shiftable radially of said cylinder block, and a cam ring which can be adjusted by rocking it around said output shaft from outside to adjust the degree of movement of said ball pistons in the corresponding oil chambers, thereby adjusting an amount of working oil discharged from said variable hydraulic pump.
37. A variable speed transmission according to claim 35 wherein said hydraulic motor is a crescent hydraulic motor and said reduction gear is a planetary reduction gear, and wherein said driving axle arrangement is constituted by the differential gear connected to said separated shafts, and said crescent hydraulic motor and said planetary reduction gear are both arranged coaxial with said separated shafts.
38. A variable speed transmission according to claim 35 wherein a single sump is provided as a source of lubricating oil for at least one of said engine and said driving axle arrangement and is also used to supply oil as an hydraulic fluid to said hydraulic pump and to said hydraulic motor.
39. A variable speed transmission according to claim 35 wherein said housing comprises 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.
40. 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.
(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.
41. The power system of claim 40 wherein said variable speed transmission comprises an hydraulic pump and an hydraulic motor.
42. The power system of claim 41 wherein said common fluid reservoir supplies fluid to at least one of said engine and said driving axle arrangement and also provides fluid to said hydraulic pump and to said hydraulic motor.
43. The power system of claim 41 wherein said common fluid reservoir supplies fluid to said engine, said hydraulic pump, and said hydraulic motor.
44. The power system of claim 43 wherein said common fluid reservoir also supplies fluid to said driving axle arrangement.
45. 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.
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.
46. An off road vehicle comprising:
a vehicle body having a unitized power system mounted thereon, the power system including an engine and drive train, the engine having an output shaft and the drive train having driven shafts, comprising:
(a) 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 pressure from said variable hydraulic pump into driving power, a reduction hear 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.
a vehicle body having a unitized power system mounted thereon, the power system including an engine and drive train, the engine having an output shaft and the drive train having driven shafts, comprising:
(a) 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 pressure from said variable hydraulic pump into driving power, a reduction hear 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.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US16102688A | 1988-02-26 | 1988-02-26 | |
| US07/161,026 | 1988-02-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1325979C true CA1325979C (en) | 1994-01-11 |
Family
ID=22579489
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 592023 Expired - Fee Related CA1325979C (en) | 1988-02-26 | 1989-02-24 | Unitized power system and vehicles employing same |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1325979C (en) |
-
1989
- 1989-02-24 CA CA 592023 patent/CA1325979C/en not_active Expired - Fee Related
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