Machine element or mechanism – Control lever and linkage systems – Multiple controlled elements
Reexamination Certificate
2001-01-05
2003-12-02
Butler, Douglas C. (Department: 3683)
Machine element or mechanism
Control lever and linkage systems
Multiple controlled elements
C091S522000, C137S636200, C267S150000, C074S491000, C074S47100R, C180S333000, C180S006200
Reexamination Certificate
active
06655229
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an operation lever device, and more particularly to an operation lever device which can output an oil pressure signal by twisting an operation lever.
2. Description of the Related Art
The bulldozer is provided with a blade. The blade is operated to perform “blade up, down, and float”, “right tilt and left tilt”, and “right angle and left angle”. To make such operations, the bulldozer is provided with hydraulic cylinders and flow rate control valves for respective operations. Specifically, the bulldozer is provided with a blade up-and-down flow-rate control valve, a tilting flow-rate control valve and an angle control valve. Those three flow rate control valves are driven by operating the hydraulic operation lever. More specifically, when the hydraulic operation lever is operated, a pilot pressure corresponding to an operated amount is applied to respective pilot ports of the flow rate control valves. And, a pressure oil with a flow rate corresponding to the pilot pressure applied to each pilot port is supplied to the each hydraulic cylinder. Thus, the blade is operated.
When it is necessary to operate three flow rate control valves, namely operation objects for three axes by at least two operation levers, the operations are troublesome, placing a burden on the operator.
Therefore, an operation lever device which can operate the operation objects for three axes by a single operation lever has been proposed heretofore.
Japanese Patent Publication No. 3-44326 describes an invention of an electric operation lever device which can operate the operation objects for three axes by freely operating an electric operation lever in three directions of back and forth, right and left, and twisting.
But, the electric operation lever needs a sensor such as a potentiometer in order to detect an operated amount. And, a controller and an electromagnetic proportion valve are also needed to convert an electric signal output from the electric operation lever into an oil pressure signal. Accordingly, it has disadvantages that the number of components is increased and the structure becomes complex.
Japanese Patent Application Laid-Open Publication No. 7-117705 also describes an invention of an operation lever device which can operate operation objects for three axes by freely operating an operation lever in three directions of back and forth, right and left, and twisting.
Such an operation lever device has a structure having the operation lever connected to a spool of the flow rate control valves by a link mechanism. Operation of the operation lever directly pushes or pulls the spool of the flow rate control valve through the link mechanism.
But, the above link structure for the three axes is complex. It has disadvantages that its components require high accuracy, and the assembly and adjustment of the operation lever device require a great deal of time. It also has drawbacks that the force to operate the operation lever has to be high and the operator becomes tired easily because the spool of the flow rate control valve is directly pushed or pulled through the link mechanism. Besides, the operation lever and the flow rate control lever are mutually disposed uniquely and must be accurate because the operation lever is connected to the spool of the flow rate control valve through the link mechanism. Thus, there is another disadvantage that the layout of the respective equipment is restricted.
Meanwhile, an invention related to a biaxial hydraulic operation lever device which can output an oil pressure signal when the operation lever is operated in a back and forth direction and a right and left direction is known well. But, an invention directed to a hydraulic operation lever device which can output an oil pressure signal by operating the operation lever in a twisting direction has not be achieved yet.
It is a first object of a first aspect of the present invention to make it possible to output an oil pressure signal by operating the operation lever in the twisting direction, to make a structure simple, to facilitate its assembly and adjustment, to lower its operation force, and to eliminate the restriction of its layout.
The operation lever device used for construction machines such as a bulldozer is sometimes provided with a mechanism for keeping the operation lever in a tilted state. The mechanism for keeping the operation lever in the tilted state is called a detent mechanism.
But, it was found that the disposition of the detent mechanism for the operation lever device which operates the operation lever in three directions of back and forth, right and left, and twisting has the following drawbacks.
Specifically, when shaft section
8
c
of the operation lever of
FIG. 2
is tilted, the bottom surface of disk plate
9
comes into contact with top end (stopper)
12
a
of plate
12
. At the time, when the detent mechanism is operating, the shaft section
8
c
of the operation lever is fixed in a tilted position.
When the shaft section
8
c
of the operation lever in the aforesaid state is twisted, frictional force is produced between the bottom surface of the disk plate
9
and the top end
12
a
of the plate
12
. Therefore, even if the hand is moved off the operation lever after the shaft section
8
c
of the operation lever is twisted, the shaft section
8
c
of the operation lever does not return smoothly to the original neutral position because of the frictional force.
It is a second object of a second aspect of the invention to enable the operation lever return to the original neutral position smoothly when the hand is moved off the operation lever after it is twisted.
OBJECTS AND SUMMARY OF THE INVENTION
Therefore, in order to achieve the first object, the first aspect of the invention is an operation lever device which moves pistons (
5
,
6
) according to an operation of operation lever (
8
), outputs an oil pressure signal according to the movement of the pistons (
5
,
6
) and operates operation object (
33
) according to the oil pressure signal, and is comprised of twisting means (
13
,
14
,
15
) for twisting the operation lever (
8
) about lever axis (
8
a
), and conversion means (
18
,
19
) for converting the motion to twist the operation lever (
8
) about the lever axis (
8
a
) into motion to move the pistons (
5
,
6
).
The first aspect of the invention will be described specifically with reference to FIG.
2
.
According to the first aspect of the invention, when the operation lever
8
is twisted about the lever axis
8
a
, the shaft
13
supported by the bearings
14
,
15
is twisted. The twist of the shaft
13
is converted into the movement in a direction that the piston
5
is moved by the first lever
18
and the second lever
19
, and the piston
5
is moved. When the piston
5
is moved, the oil pressure signal is output from discharge port
25
.
According to the first aspect of the invention, the operation lever device
10
may be provided with a mechanism for twisting the operation lever
8
and a mechanism for converting the twist into motion to move the piston
5
. Therefore, it is different from a conventional electric operation lever device and has a simple structure without requiring a sensor, a controller and the like.
Besides, it is not a structure to directly push or pull the spool of the flow rate control valve by a link mechanism but follows a structure to output the oil pressure signal according to the movement of the pistons in the same way as the conventional hydraulic operation lever device. Therefore, the operation lever device can be assembled and adjusted easily without necessitating lots of time. Because the pistons are moved by operating the operation lever in the same way as the conventional hydraulic operation lever device, the operation lever is operated by the same small force as before, and an operator does not get tired. Besides, it is not a structure having the operation lever and the spool of the flow rate control valve connected by a link mechanism but a st
Hori Shuuji
Ishizaki Naoki
Satou Yasuhiro
Yamamoto Yuuichi
Butler Douglas C.
Komatsu Ltd.
Varndell & Varndell PLLC
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