Motor vehicles – Steering by driving
Reexamination Certificate
2000-06-13
2002-10-08
Boehler, Anne Marie (Department: 3611)
Motor vehicles
Steering by driving
C180S333000
Reexamination Certificate
active
06460639
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a driving control device for a vehicle device to control the traveling of the vehicle device by tilting a single operation lever of an operation lever device forward, backward, right or left.
2. Description of the Related Art
For example, a driving control device for a vehicle device, which controls traveling of a vehicle device such as a bulldozer by tilting a single operation lever, is already know.
FIG. 16
shows an example of a driving control device for a conventional bulldozer (vehicle device). FIGS.
17
(
a
) and
17
(
b
) show appearance of the operation lever device configuring the above driving control device, and
FIG. 18
shows an inside structure of the operation lever device.
It is seen from
FIG. 18
that operation lever device
205
has device body
207
and operation lever
206
which is mounted to be tiltable on the device body
207
through universal joint
250
.
The universal joint
250
is provided with piece member
213
which has support shaft
209
and support shaft
210
mutually intersecting at right angles as shown in FIG.
19
. The piece member
213
is connected to forked bracket
212
fixed to mounting plate
211
through the support shaft
210
. The operation lever
206
is connected to the piece member
213
through the support shaft
209
.
The operation lever
206
can be tilted in two directions so to mutually intersect at right angles with the device body
207
through the universal joint
250
as described above.
The device body
207
has four pistons
201
,
202
,
203
,
204
, a housing for accommodating the pistons
201
to
204
and mounting plate
211
.
The device body
207
has top ends of the four pistons
201
,
202
,
203
,
204
protruded, from the top mounting plate
211
. The four pistons
201
to
204
are disposed to form a square when viewed from above as shown in FIG.
17
(
a
).
Disk plate
208
having a substantially disk form is connected to the operation lever
206
. The disk plate
208
has its undersurface contacted with the top ends of the respective pistons
201
,
202
,
203
,
204
when the operation lever
206
is neutral.
The term neutral is used to mean a state that pressure reducing valves
218
to
221
do not output a signal in FIG.
16
. Generally, it is configured that the operation lever
206
is parallel to the respective pistons
201
,
202
,
203
,
204
and perpendicular to the mounting plate
211
as shown in FIG.
18
.
Accordingly, when the operation lever is tilted, the respective pistons
201
,
202
,
203
,
204
are moved according to a tilted direction and amount of the operation lever
206
.
As shown in
FIG. 16
, the operation lever device
205
is supplied with a pilot pressure oil from fixed displacement hydraulic pump
222
. Relief valve
222
V and tank
223
are connected to the operation lever device
205
.
The pistons
201
,
202
,
203
,
204
are respectively provided with the pressure reducing valves
218
,
219
,
220
,
221
via an unshown set spring. Output ports of the pressure reducing valves
218
,
219
,
220
,
221
are connected to the pilot pipe passages
214
,
215
,
216
,
217
respectively.
Next, the operation will be described with reference to FIG.
18
. When the operation lever
206
which is in the neutral position is tilted about the support shaft
209
to the left in the drawing (in a direction of forward F), the piston
204
is pushed down in a direction of arrow A by the disk plate
208
.
Then, stroke S (displacement) of the piston
204
has a magnitude corresponding to a tilted amount of the operation lever
206
.
When the piston
204
is pushed down, the pressure reducing valve
218
increases its opening area through the set spring. The pressure reducing valve
218
outputs a pilot pressure corresponding to the opening area to the pilot pipe passage
214
.
The opening area of the pressure reducing valve
218
is determined depending on a balance between the output pilot pressure and the spring tension. The spring tension in the balance position corresponds to stroke S. Therefore, pilot pressure Pp output from the pilot pipe passage
214
has the magnitude corresponding to the tilted amount of the operation lever
206
.
FIG. 20
shows a relation between the stroke S and the pilot pressure Pp. When the operation lever
206
is operated to move the piston
204
from stroke position S
0
corresponding to the neutral position shown in
FIG. 18
to position SF to output maximum output Ppmax, the pilot pressure Pp output from the pilot pipe passage
214
is variable from drain pressure Pp
0
of the tank
223
to set pressure Ppmax of the relief valve
222
V.
It is designed that when the piston
204
reaches position SF to output the maximum output Ppmax, the operation lever
206
stops its stroke and its further movement is restricted.
The zone between the stroke position S
0
and position Si is a dead zone, in which the pilot pressure Pp output from the pilot pipe passage
214
remains to be drain pressure Pp
0
and does not change even if the operation lever
206
is tilted.
It was described above that the piston
204
is moved according to the tilting of the operation lever
206
, and the oil pressure signal indicating the pilot pressure Pp is output from the pilot pipe passage
214
. The oil pressure signal indicating the pilot pressure Pp is also output from the pilot pipe passages
215
,
216
,
217
in the same way when the pistons
201
,
202
,
203
are moved according to the titling of the operation lever
206
.
The bulldozer having the driving control device of
FIG. 16
is provided with left crawler
236
and right crawler
238
on the left and right sides of its body. The left crawler
236
is driven by left traveling hydraulic motor
235
. The right crawler
238
is driven by right traveling hydraulic motor
237
.
The left traveling hydraulic motor
235
is an actuator for operating the left crawler
236
in two directions, namely forward and backward. The right traveling hydraulic motor
237
is an actuator for operating the right crawler
238
in two directions, namely forward and backward.
The operation lever device
205
is connected to swash plate control cylinders
230
,
231
for left and right variable displacement hydraulic pumps
233
,
234
through drive signal generation circuit
229
. The left and right for variable displacement hydraulic pumps
233
,
234
are connected to the left and right hydraulic motors
235
,
237
respectively.
The drive signal generation circuit
229
comprises shuttle valves
225
,
226
,
227
,
228
for comparing oil pressure signals output from the two neighboring pistons (
203
and
204
,
204
and
201
,
201
and
202
or
202
and
203
) to output a signal of a larger pressure.
The pilot pipe passage
214
is connected to port F which is an inlet port for either of the shuttle valves
225
,
226
. Similarly, the pilot pipe passage
215
is connected to port B. The pilot pipe passage
216
is connected to port R. The pilot pipe passage
217
is connected to inlet port L.
Outlet port of the shuttle valve
225
is connected to cylinder chamber
230
F of the swash plate control cylinder
230
. Outlet port of the shuttle valve
226
is connected to cylinder chamber
231
F of the swash plate control cylinder
231
. Outlet port of the shuttle valve
227
is connected to cylinder chamber
231
B of the swash plate control cylinder
231
. Outlet port of the shuttle valve
228
is connected to cylinder chamber
230
B of the swash plate control cylinder
230
.
Pressure oil supplied to the cylinder chamber
230
F tilts the swap plate of the variable displacement hydraulic pump
233
to make a forward rotation of the left traveling hydraulic motor
235
so to move forward the left crawler
236
. The pressure oil supplied to the cylinder chamber
230
B tilts the variable displacement hydraulic pump
233
to make backward rotation of the left traveling hydraulic motor
235
so to move backward the left crawler
236
.
Similarly, the pressu
Hori Shuuji
Mototani Masayoshi
Boehler Anne Marie
Komatsu Ltd.
Varndell & Varndell PLLC
Winner Tony
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