Power plants – Pressure fluid source and motor – With means purging – cleaning or separating undesirables from...
Reexamination Certificate
2000-09-29
2001-12-04
Ryznic, John E. (Department: 3745)
Power plants
Pressure fluid source and motor
With means purging, cleaning or separating undesirables from...
C074S60600R
Reexamination Certificate
active
06324842
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an axle driving apparatus including a hydrostatic transmission (HST), axles and a transmitting mechanism transmitting power to the axles, all of which are integrally provided in a housing of the axle driving apparatus. A power take off (PTO) transmission system for driving four wheels of a vehicle is compactly included in the housing.
The axle driving apparatus of the present invention also relates to the placement of a filter for filtering supply oil for the HST, and to the placement of a reserve tank regulating the volume of oil which varies with an increase of temperature of the HST.
Furthermore, the axle driving apparatus of the present invention relates to a compact arrangement of a differential locking system, which prevents bending or tilting of a differential input gear under heavy loads.
2. Related Art
A conventional axle driving apparatus includes axles and a transmitting mechanism interconnecting an HST to the axles housed in a housing. For example, U.S. Pat. No. 5,456,068, discloses an axle driving apparatus wherein an input shaft, namely a pump shaft of an HST, is disposed vertically and an output shaft, namely a motor shaft of the HST, is disposed horizontally and parallel to the axles.
Conventionally, a PTO unit is attached to such an axle driving apparatus described above. U.S. Pat. Nos. 5,367,877 and 5,515,677, for example, disclose a PTO unit separate from an axle driving apparatus and attached to a rear surface of the axle driving apparatus, projecting from the rear of the axle driving apparatus.
In cases where the input shaft of the HST is disposed vertically, as in the above-mentioned patents, the housing is vertically shorter, however, it is longitudinally and laterally longer. The input shaft necessarily projects upward, thereby requiring a predetermined space for a pulley or a sprocket above the housing. In cases where the axle driving apparatus has a vertically disposed input shaft and a PTO shaft, directional control of the axle driving apparatus requires a gear train of bevel gears or similar means because the PTO shaft is necessarily disposed horizontally. Thus, a housing including such a gear train is large. Furthermore, a casing supporting the PTO shaft projects rearwardly thereby also requiring a large space.
In an operating oil circulation system of an HST housed in a conventional axle driving apparatus, an oil filter for filtering operating oil of the HST is located in a lower portion in the housing. A reserve tank is conventionally located in an upper portion of the housing or adjacent the axle driving apparatus via piping, whereby the reserve tank is distant from the oil filter.
Accordingly, the mounting structure of the reserve tank is separate from that of the oil filter. Also, when the oil filter needs to be removed due to clogging or periodic maintenance, it can be removed only after all the operating oil is drained from the housing. Thus, removing the oil filter is a time consuming, costly and complicated process.
Furthermore, conventional differential gearing of the transmitting mechanism interconnecting the HST with the axles housed in the housing is occasionally provided with a differential locking system to restrict rotation of the differential and enable the vehicle to easily travel on a soft field.
To lock the conventional differential gearing, a differential casing is locked with a differential input gear, a differential side gear and a differential pinion via pins or other suitable means. A conventional driving apparatus housing is large when a differential casing is also disposed in the housing along with the HST, the axles and the transmitting mechanism. However, if the differential locking system is not provided with a differential casing, the differential input gear lacks adequate strength and support in cases of heavy traction. In this case, the differential input gear generates eccentric forces due to partial engagement of teeth thereof thereby reducing durability of the differential gearing.
SUMMARY OF THE INVENTION
The first object of the present invention is to provide an axle driving apparatus including an input shaft having a longitudinal axis of rotation, axles having lateral axes of rotation, and a PTO shaft having a longitudinal axis of rotation housed in a housing, wherein a PTO transmission system is compactly housed in the housing.
To attain the first object, the housing includes at least two housing members which join each other in a longitudinal direction. One housing member houses an HST driven by the input shaft and a first transmitting mechanism transmitting the power output from the HST to the axles. The other housing member separately houses a second transmitting mechanism transmitting the power of the input shaft to the PTO shaft.
The housing also includes front (or first), middle (or second) and rear (or third) housing members joining one another in a longitudinal direction. First and second chambers are formed between the front and middle housing members. A third chamber is formed between the middle and rear housing members. An HST driven by the input shaft is disposed in one of the first and third chambers. The transmitting mechanism transmitting power from the HST to the axles is disposed in the second chamber. And the transmitting mechanism transmitting the power of the input shaft to the PTO shaft is disposed in the other of the first and third chambers.
The HST also includes a hydraulic pump connected with the input shaft, a hydraulic motor connected with the axles, and a center section supporting and fluidly interconnecting the hydraulic pump and the hydraulic. The axis of rotation of the hydraulic pump substantially coincides with that of the input shaft. The axis of rotation of the hydraulic motor is disposed substantially parallel to that of the axles. The hydraulic pump and motor are disposed above the axles such that the hydraulic pump is disposed between the hydraulic motor and the axles.
Furthermore, an axle housing is formed integrally with one of the housing members. A steering casing for four-wheel-drive applications is attached to an end of the axle housing.
Also, the PTO shaft is disposed adjacent to the axles, whereby the transmitting mechanism drivingly connecting the hydraulic motor with the axles overlaps the transmitting mechanism transmitting power of the input shaft to the PTO shaft when viewed from the side of the axle driving apparatus.
In one embodiment, the front, middle and rear housing members join each other in a longitudinal direction and the first, second and third chambers are formed in the housing. The other of the first and third chambers is fluidly connected with the second chamber, and one of the first and third chambers is fluidly connected with the second chamber through an oil filter.
Furthermore, the transmitting mechanism transmitting power to the PTO shaft includes an oil clutch capable of switching ON and OFF. The driving apparatus includes a charge pump driven by the input shaft to feed the oil clutch with operating oil. The oil discharged from the charge pump serves as operating oil for the HST. One of the housing members forms a recessed portion projecting into one of the first and third chambers. The oil clutch disposed in the other of the first and third chambers faces the inside of the recessed portion.
A second object of the present invention is to provide an axle driving apparatus including an input shaft having a longitudinal axis of rotation and axles having a lateral axes respectively housed in a housing which forms an oil sump therein. An oil filter and an HST are disposed in the oil sump to enable the HST to utilize oil filtered through the oil filter. The oil filter and a reserve tank are disposed to ease removal of the oil filter.
An opening sized to enable insertion and removal of the oil filter from the inside of the housing is formed at the upper portion of the housing and a cover means is provided for covering the opening. Also, the cover means includes
Kanzaki Kokyukoki Mfg. Co. Ltd.
Ryznic John E.
Sterne Kessler Goldstein & Fox PLLC
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