Self-propelled snowplow vehicle

Details Self-propelled snowplow vehicle Self-propelled snowplow vehicle

2002-09-10

2004-03-16

Batson, Victor (Department: 3671)

Excavating

Snow or ice removing or grooming by portable device

Motorized rotary excavating tool

C037S257000

Reexamination Certificate

active

06705028

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a self-propelled snowplow vehicle having a driving wheel for driving the snowplow vehicle and an auger for removing snow.
DESCRIPTION OF THE RELATED ART
In a snowplow vehicle equipped with a snow-removing anger, a system is employed to ensure that the vertical level or height of the auger can be changed in view of snow-removing conditions. When the snowplow vehicle moves from one place to another, the auger is preferably kept in a raised position to facilitate smooth movement of the snowplow vehicle. On the other hand, when a snow-removing operation is to be achieved, the auger is preferably moved to a lower position to achieve the snow-removing operation with improved efficiency. During the snow-removing operation, the auger is frequently raised and lowered in harmony with angulations on the ground surface. Frequent rising and lowering operation of the auger, when achieved manually, is laborious. To lighten the load on the human operator, an improved self-propelled snowplow vehicle has been proposed, which is equipped with a power-operated vertically swingable auger, as disclosed in Japanese Patent Laid-open Publication No. HEI 4-194109.
The disclosed snowplow vehicle includes a propelling frame equipped with left and right crawler belts, a vehicle frame equipped with an auger and pivotally connected to the propelling frame, and a lift control device operable to lift a front end portion of the vehicle frame up and down relative to the propelling frame. The lift control device is comprised of a cylinder actuator operable, under the control of a control unit, to extend or contract its piston rod to thereby lift the vehicle frame front end portion and the auger in an upward or a downward direction in response to pivotal movement of a manual operating lever provided on an operating part of the snowplow vehicle.
The cylinder actuator constituting the lift control device needs a power source for operation thereof. In the case where the cylinder actuator is an oil hydraulic cylinder actuator, a separate hydraulic power unit must be provided. Accordingly, the overall size of the lift control device is relatively large. Thus, the use of the oil hydraulic cylinder actuator is quite disadvantageous when the snowplow vehicle is relatively small in size.
In order to achieve downsizing of the lift control device, use of an electro-hydraulic cylinder actuator may be considered. The electro-hydraulic cylinder actuator has an electric motor drivable to produce a hydraulic pressure used for reciprocating a piston rod of the cylinder actuator. The electric motor and a hydraulic power unit such as a pump are assembled with a cylinder of the cylinder actuator, so that the electro-hydraulic cylinder actuator is relatively small in size. The electric motor is controlled to extend or contract the piston rod of the cylinder actuator to thereby raise or lower the auger in response to on-off operation of an operation switch.
Since the height of the auger is changed in view of snow-removing conditions, it may occur that the operation switch is kept in the activated state even after the piston rod arrives at its fully extended or fully contracted position. On this occasion, the electric motor is subjected to a heavy load for a long time. Additionally, during snow-removing operation, since the height of the auger is frequently changed in harmony with angulations of the ground surface, the electro-hydraulic cylinder actuator is forced to operate repeatedly with high frequencies. Under such condition, the duty cycle of the electric motor is very high and generation of heat from the electric motor is promoted.
To deal with this problem, use of a continuously operable electric motor may be considered. The continuously operable electric motor is, however, expensive and hence increases the cost of the snowplow vehicle. As an alternative measure, use of a thermo-breaker may be considered for the purpose of protecting the motor from overheating. The thermo-breaker is generally built in the electric motor and operates to cut off or open a power supply circuit to the electric motor when the electric motor heats up above a given temperature.
The thermo-breaker is designed to continue the “open” state of the power supply circuit until the electric motor cools to a satisfactory operating temperature. Accordingly, a downtime occurs each time the thermo-breaker operates. In case where the operating temperature of the thermo-breaker is set to a relatively low value, the power supply circuit to the electric motor may be frequently cut off by the thermo-breaker. Alternatively, when the operating temperature of the thermo-breaker is set to a relatively high value, the power supply circuit to the electric motor may be cut off infrequently. In the latter case, however, the thermo-breaker requires a relatively long time to recover its original inoperating state. To enable smooth snow-removing operation, the frequency of operation of the thermo-breaker should preferably be reduced
To this end, an arrangement may be considered, in which a detection switch is associated with the electro-hydraulic cylinder actuator such that when arrival of the piston rod of the cylinder actuator at its fully extended or fully contracted position is detected by the detection switch, the detection switch generates a signal to stop operation of the electric motor. This arrangement may reduce the occurrence of overloaded condition of the electric motor. However, use of the detection switch necessarily increases the number of parts of the cylinder actuator and requires an electric wiring system, leading to an increased cost of the snowplow vehicle.
FIGS. 16A
to
16
C are diagrammatical views illustrative of the operation of a conventional self-propelled snowplow vehicle
500
. In
FIG. 16A
, the snowplow vehicle
500
is shown with a snow-removing auger
503
disposed in a lowermost horizontal position. The snowplow vehicle
500
is moving forward by the action of crawlers
501
(one being shown) while removing snow by means of the auger
503
and a blower
504
rotatably driven by an engine
502
. The auger
503
collects snow and the blower
504
blows the collected snow away from the snowplow vehicle
500
through a shooter
505
. In this instance, a travel control lever
511
provided on a control board
510
is disposed in an “F” (forward) position, and an auger lift control lever
512
also provided on the control board
510
is disposed in a “DN” (down) position.
Due to a large amount of snow to be removed or in order to change the advancing direction of the snowplow vehicle
500
, the snowplow vehicle
500
is occasionally moved backward. In this instance, as shown in
FIG. 16B
, the travel control lever
511
on the control board
510
is shifted from the “F” (forward) position to an “N” (neutral) position as indicated by the arrow {circle around (
1
)} whereupon the snowplow vehicle
500
stops moving in the forward direction. Then, the auger lift control lever
512
is shifted from the “DN” (down) position to an “UP” (up) position as indicated by the arrow {circle around (
2
)} whereupon lift cylinder actuators
506
(one being shown) operate to extend their piston rods to thereby lift a front end portion of a vehicle frame
508
upward relative to a propelling frame
507
on which the crawlers
501
(
FIG. 16A
) are mounted. The auger
503
is thus raised to an uppermost elevated inclined position.
Then as shown in
FIG. 16C
, the travel control lever
511
on the control board
510
is shifted from the “N” (neutral) position to an “R” (reverse) position as indicated by the arrow {circle around (
3
)} whereupon the snowplow vehicle
500
moves backward. As described above, in order to reverse the snowplow vehicle while moving in the forward direction, the conventional snowplow vehicle requires three consecutive steps of manual operation as indicated by the arrows {circle around (
1
)}-{circle around (
3
)}. Conversely, when the snowplow vehicle while moving backward is to be moved i

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