Dual tilt control system for work vehicle

Details Dual tilt control system for work vehicle Dual tilt control system for work vehicle

2001-03-30

2002-11-19

Batson, Victor (Department: 3671)

Earth working

Mounting for pushed tool at end of motor vehicle

Transversely mounted blade

C091S448000, C091S531000

Reexamination Certificate

active

06481506

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a dual tilt control system for a work vehicle, the system controlling a blade pivotably connected to a vehicle body by means of a pair of left and right tilt cylinders for pitch and tilt operations.
BACKGROUND OF THE INVENTION
Conventionally, a work vehicle such as a bulldozer excavates, carries soil and levels the ground after excavation by means of a blade coupled to the front of a vehicle body through a pair of straight frames. One known technique of controlling the blade is as follows. A pair of left and right tilt cylinders (pitch cylinders), that is, double-acting hydraulic cylinders are provided between the blade and the vehicle body. When these tilt cylinders are driven simultaneously so as to extend or retract, the blade assumes a pitch dump posture (forward-tilting posture) or a pitch back posture (backward-tilting posture). When one of the tilt cylinders is driven so as to extend or retract with the other tilt cylinder remaining at rest, the blade assumes such a posture (right-tilting posture or left-tilting posture) that its right edge or its left edge tilts downward.
There is also disclosed what is called a dual tilt control system (e.g., in Japanese Patent Publication No. 63-501228 (1988)) which drives one of the tilt cylinders for extension while driving the other tilt cylinder for retraction, thereby obtaining an increased velocity at which the blade is actuated to tilt.
The conventional dual tilt control system is explained further with reference to a hydraulic circuit diagram shown in
FIG. 5. A
dual tilt control system
100
controls a right tilt cylinder
101
and a left tilt cylinder
102
, which connect the blade (not shown) and the vehicle body (not shown), for pitch and tilt operations.
In the dual tilt control system
100
, a directional control valve
105
is connected to a hydraulic pump
103
and to a tank
104
and has control ports
106
,
107
connected to respective valve ports
110
,
111
of a two-position switching type pitch control valve
108
and a two-position switching type tilt control valve
109
, respectively. The pitch control valve
108
also has a cylinder port
112
connected to a bottom oil chamber
102
a
of the left tilt cylinder
102
and cylinder ports
113
,
114
connected to a bottom oil chamber
101
a
and a head oil chamber
101
b
of the right tilt cylinder
101
, respectively. The tilt control valve
109
also has a cylinder port
115
connected to a head oil chamber
102
b
of the left tilt cylinder
102
and cylinder ports
116
,
117
connected to the bottom oil chamber
101
a
and the head oil chamber
101
b
of the right tilt cylinder
101
, respectively. The right tilt cylinder
101
is of larger diameter than the left tilt cylinder
102
so that the head oil chamber
101
b
of the right tilt cylinder
101
and the bottom oil chamber
102
a
of the left tilt cylinder
102
can be of equal cross-sectional area. When an operating lever (not shown) is manipulated, the directional control valve
105
, the pitch control valve
108
and the tilt control valve
109
are actuated upon receipt of electric signals or pilot pressure signals.
In the case of pitch dump, the directional control valve
105
and the tilt control valve
109
are switched to their respective positions A, while the pitch control valve
108
is switched to position B. Pressure oil discharged from the hydraulic pump
103
is thus supplied through the control port
106
of the directional control valve
105
, the valve port
110
and the cylinder port
113
of the pitch control valve
108
to the bottom oil chamber
101
a
of the right tilt cylinder
101
, thereby actuating the right tilt cylinder
101
in an extending direction. The pressure oil from the head oil chamber
101
b
of the right tilt cylinder
101
is supplied through the cylinder ports
114
,
112
of the pitch control valve
108
to the bottom oil chamber
102
a
of the left tilt cylinder
102
, thereby also actuating the left tilt cylinder
102
in the extending direction. The pressure oil within the head oil chamber
102
b
of the left tilt cylinder
102
is exhausted through the cylinder port
115
, the valve port
111
of the tilt control valve
109
and the control port
107
of the directional control valve
105
to the tank
104
. The right and left tilt cylinders
101
,
102
are thus extended simultaneously at an equal velocity, and consequently, the blade performs pitch dump (tilts forward). In the case of pitch back, the directional control valve
105
is switched to position B with the pitch control valve
108
and the tilt control valve
109
remaining in position B and position A, respectively. The pressure oil thus flows reversely to the direction described above, so that the right and left tilt cylinders
101
,
102
are retracted simultaneously at an equal velocity. Consequently, the blade performs pitch back (tilts backward).
In the case of dual tilting to the right, the directional control valve
105
and the pitch control valve
108
are switched to their respective positions A, while the tilt control valve
109
is switched to position B. The pressure oil discharged from the hydraulic pump
103
is thus supplied through the control port
106
of the directional control valve
105
, the valve port
110
and the cylinder port
112
of the pitch control valve
108
to the bottom oil chamber
102
a
of the left tilt cylinder
102
, thereby actuating the left tilt cylinder
102
in the extending direction. The pressure oil from the head oil chamber
102
b
of the left tilt cylinder
102
is supplied through the cylinder ports
115
,
117
of the tilt control valve
109
to the head oil chamber
101
b
of the right tilt cylinder
101
, thereby actuating the right tilt cylinder
101
in a retracting direction. The pressure oil within the bottom oil chamber
101
a
of the right tilt cylinder
101
is exhausted through the cylinder port
116
, the valve port
111
of the tilt control valve
109
and the control port
107
of the directional control valve
105
to the tank
104
. The extension of the left tilt cylinder
102
and the retraction of the right tilt cylinder
101
are thus carried out simultaneously, and consequently, the blade tilts to the right at a high velocity (substantially double the normal velocity). In the case of dual tilting to the left, the directional control valve
105
is switched to position B with the pitch control valve
108
and the tilt control valve
109
remaining in position A and position B, respectively. The pressure oil thus flows reversely to the direction described above, so that the extension of the right tilt cylinder
101
and the retraction of the left tilt cylinder
102
are carried out simultaneously. Consequently, the blade tilts to the left at a high velocity (substantially double the normal velocity).
In the case of single tilting to the right, the directional control valve
105
, the pitch control valve
108
and the tilt control valve
109
are switched to their respective positions A. The pressure oil discharged from the hydraulic pump
103
is thus supplied through the control port
106
of the directional control valve
105
, the valve port
110
, the cylinder port
112
of the pitch control valve
108
to the bottom oil chamber
102
a
of the left tilt cylinder
102
, thereby actuating the left tilt cylinder
102
in the extending direction. The pressure oil from the head oil chamber
102
b
of the left tilt cylinder
102
is exhausted through the cylinder port
115
, the valve port
111
of the tilt control valve
109
and the control port
107
of the directional control valve
105
to the tank
104
. Only the extension of the left tilt cylinder
102
is thus carried out with the right tilt cylinder
101
remaining at rest, and consequently, the blade tilts to the right at a normal velocity (low velocity). In the case of single tilting to the left, the directional control valve
105
is switched to position B with the pitch control valve
108
and the tilt contr

Affiliated with

Also associated with

Rating

Dual tilt control system for work vehicle does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Dual tilt control system for work vehicle, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dual tilt control system for work vehicle will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2991872