Power plants – Pressure fluid source and motor – Having condition responsive control in a system of distinct...
Reexamination Certificate
2002-02-28
2004-02-10
Look, Edward K. (Department: 3745)
Power plants
Pressure fluid source and motor
Having condition responsive control in a system of distinct...
C060S449000, C060S448000, C180S006200, C180S006480
Reexamination Certificate
active
06688102
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a traveling control device to be applied to construction machinery equipped with a crawler type traveling body like a hydraulic excavator.
2. Description of the Related Art
The prior art will be described hereinafter with hydraulic excavator by way of example.
The conventional traveling control device (a hydraulic circuit) for controlling the operation of the crawler type traveling body in the hydraulic excavator is depicted in FIG.
6
.
As shown in
FIG. 6
, the traveling control device is constituted with a hydraulic motor for a left traveling body
11
and a hydraulic traveling motor for a right traveling body
12
(hereinafter, they are referred to as a left traveling motor, and a right traveling motor). Both traveling motors
11
and
12
are operated by hydraulic pumps
13
and
14
(hereinafter, they are referred to as a left hydraulic pump, and a right hydraulic pump), respectively.
In addition, motor circuits
15
and
16
connect two motors
11
and
12
, two (a right and a left) pumps
13
and
14
, and a tank T, and hydraulic pilot type control valves
17
and
18
are installed in each circuit. The control valves
17
and
18
are converted and controlled by a remote control pressure from remote control valves
19
and
20
that are operated by levers (or pedals)
19
a
and
20
a.
In this way, the rotational direction (forward, backward) and the rotational speed (traveling speed) of both traveling motors
11
and
12
are controlled.
In other words, when the remote control valves
19
and
20
are operated, the control valves
17
and
18
are operated by the stroke in accordance with the control input of the remote control valves, which consequently determining an opening of the valve. And, the flaw rate according to the valve opening is supplied to the traveling motors
11
and
12
, raising the pump pressure, and operating the traveling motors
11
and
12
.
Incidentally, in the conventional traveling control device, the relation between the control input of the remote control valves
19
and
20
(hereinafter, it is referred to as the control input) and the pump pressure from the reaction manifests exactly the same properties, without any difference in two different cases, such as:
(a) double traveling in which both traveling motors
11
and
12
rotate simultaneously; and
(b) single traveling in which only one of the traveling motors
11
and
12
rotates.
However, during the single traveling, since the load operated by one traveling motor is comparatively larger than that of the double traveling, the control input necessary for the operation gets relatively increased. That is, the double traveling can be traveled even at the slight operation, while the single traveling will not start the traveling unless it is operated deeply.
Therefore, during the single traveling, the control input after the operation is small, causing the micro-operational ability within the range of the control input after the operation to be deteriorated.
On the other hand, if the single traveling at a small control input is possible, this speeds up the operation of the double traveling too much (because of the increased sensitivity of the small control input). In result, the traveling may start suddenly, and the micro-operation at the small control input is deteriorated.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a traveling control device for properly applying single traveling as well as double traveling in accordance with its own properties.
The traveling control device of the present invention comprises: a crawler type right and left traveling body; a right and a left hydraulic motors for operating the right and left traveling body, using each hydraulic pump as a hydraulic source; an operating means for outputting an operation command to the both hydraulic motor; and a pump pressure control means for controlling the pump pressure supplied to the double hydraulic motors in accordance with the control input of the operating means. The pump pressure control means controls the pump pressure based on different properties of the pump pressure during the single traveling where only one hydraulic motor is operated, and the double traveling where both hydraulic motors are simultaneously operated.
In the present invention, considering that different properties of pump pressures are applied to the single traveling and the double traveling by the pump pressure control means, the inventors decided to utilize this property of the pump pressure for both single traveling and double traveling by way of improving the operation in overall.
Also, the pump pressure control means of the present invention is devised to control the pump pressure based on the property of the pump pressure, that is, the variation slope of the pump pressure against the control input is greater for the single traveling than for the double traveling.
According to this, the inventors tried to make the variation of the pump pressure be more steep during the single traveling, while be more gentle during the double traveling, trying to improve the micro-operation within the control input after the operation through the greatly increased control input after the operation of the one-side operation. Besides, the present invention can obtain excellent micro-operation even at the small control input during the double traveling. In short, through the present invention, it became possible to obtain excellent manipulation ability for both single traveling and double traveling.
Also, the present invention has a constitution in which said pump pressure control means controls the pump pressure based on a pump pressure property that the control input necessary for a traveling operation for the single traveling and the double traveling is almost equivalent to each other.
According to this, since the control input necessary for the traveling operation becomes almost same for the single traveling and for the double traveling, the manipulation facility thereof gets even better.
Further, the pump pressure control means of the present invention comprises a pressure control valve connected to the motor circuit that connects the hydraulic pump and the hydraulic motor, and a set pressure adjusting means for adjusting the set pressure of the pressure control valve according to the control input of the operating means.
The system aforementioned is particularly for adjusting a set pressure of the pressure control valve out of the control systems to change the properties of the pump pressure during the single traveling and the double traveling.
Also, the pressure control valve of the present invention is a cut valve, which is installed in a bypass line passing through a control valve that controls the operation of the double hydraulic motor. In addition, the pressure control valve throttles the flow rate of the bypass line, and the set pressure adjusting means controls the opening of the cut valve.
The system described above is so called a cut valve control system where the cut valve is used as the pressure control valve, and the opening of the cut valve is controlled eventually for controlling the pump pressure.
Another aspect of the present invention provides the traveling control device using the hydraulic pilot type control valve and cut valve, and a remote control valve as a means for operating the control valve. Also, the set pressure adjusting means of the present invention preferably includes a shuttle valve for withdrawing the remote control pressure from the remote control valve; a cut valve pilot line for connecting the shuttle valve; and a hydraulic pilot port of the cut valve; a hydraulic pilot type traveling switching valve for closing and opening the cut valve pilot line; and a switching valve control circuit for supplying the remote control pressure of the operated side to the traveling switching valve of the opposite side as a pilot pressure to a closing direction of the traveling switching valve.
The system described abo
Kershteyn Igor
Kobelco Construction Machinery Co., Ltd.
Look Edward K.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
LandOfFree
Traveling control device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Traveling control device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Traveling control device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3313680