Information
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Patent Grant
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6267548
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Patent Number
6,267,548
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Date Filed
Thursday, December 10, 199825 years ago
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Date Issued
Tuesday, July 31, 200122 years ago
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Inventors
-
Original Assignees
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Examiners
Agents
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CPC
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US Classifications
Field of Search
US
- 414 694
- 414 680
- 414 685
- 414 698
- 414 699
- 091 436
- 091 437
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International Classifications
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Abstract
The present invention is directed to a control circuit for automatically bringing a hydraulically operated work arm into a particular position without having to manually reverse the direction of the hydraulic operating system.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a control circuit for assisting operator effected storage of a hydraulically operated articulated work arm into an “over center” storage position. By permitting simplified operation of the work arm into the storage position, the functionality of the apparatus is increased. The control circuit includes an electrically operated valve, which may be a solenoid valve, that is operably connected to the hydraulic operating system of the work arm. Further, the control circuit includes a controller for the solenoid so that operation of the work arm into various selected positions is simplified.
2. Description of Related Art
Mobile construction equipment such as tractors outfitted with a hydraulically operated articulated work arm carrying any one of a variety of attachments are used for a wide variety of applications. In particular, they are critical machines in the construction of buildings, transportation channels, and almost any other man-made structure. A practical matter involves the transport of such equipment, such as, for example, a backhoe between the physical locations where it will be used. If the equipment is driven to the desired location over roadways, difficulties associated with the weight distribution of the equipment often arise. In particular, the overhanging, leveraged weight of the backhoe linkage assembly increases the difficulty of controlling the equipment during transportation. The effective weight of the backhoe linkage assembly can affect equipment weight balance sufficiently such that the weight remaining on the front wheels is lessened and steering control and ride comfort may be compromised.
To date, the most common approach to dealing with the undesirable weight distribution of this type of construction equipment is to add weight to the front of the machine to counter the weight of the backhoe linkage assembly. However, this solution is undesirable for several reasons. The additional weight causes the equipment to become more difficult to maneuver, especially in soft ground, more difficult to steer, and more clumsy to operate. In addition, fuel consumption is increased and the equipment cost effectiveness is decreased.
A more desirable solution to the problem of weight distribution has been to move the backhoe linkage assembly into a stored position where its weight is closer to the center of the equipment. For example, Case Corporation of Racine, Wisconsin builds backhoe-type machines with a distinctive feature, known as an “over center” system, that permits the weight of the backhoe to be moved closer to the center of the equipment, whereby the weight moment arm is reduced. By shifting the weight of the backhoe toward the equipment's center of gravity, the need for a front-end counter weight is eliminated. The “over center” position of the backhoe linkage assembly is frequently known as the “carry,” the “latched,” or the “transport” position. The “over center” system, as noted above, increases the maneuverability of the equipment, particularly in soft ground, and increases the stability of the equipment during road transportation.
While the “over center” system provides significant benefits, use of the system requires operator skills that are acquired only through experience. Thus, while not always difficult for regular users of the equipment, the technique may often be awkward for new or occasional users of the machine. The technique involves a combination of operator actions that must be completed in timed sequence. The technique of moving the backhoe into the “over center” position requires the operator to activate the lift cylinder and raise the work arm toward its uppermost position. At the moment that the lift cylinder is at its minimum length, the operator must then rapidly change the direction of the hydraulic control spool to reverse the direction of the lift cylinder operation to thereby drive the backhoe into the “over center” transport position. If the control spool is not operated at the right moment, the backhoe assembly will stop moving and will not reach the transport position. The entire process must then be repeated. First time operators and operators without significant experience often have difficulty performing the technique.
The present invention for the first time provides an apparatus for reducing the heretofore important nature of operator performance in placing equipment work arms into the over-center storage/transport position. Thus, new and less experienced operators can prepare the backhoe for travel between work sites.
SUMMARY OF THE INVENTION
The purpose and advantages of the invention are set forth in and will be apparent from the description and drawings that follow. Additional advantages of the invention will be realized and attained by the elements of the device particularly pointed out in the appended claims.
The present invention is directed to a control circuit for use in combination with an apparatus having a hydraulically operated articulated work arm that is movable over a range of positions. More particularly, the present invention involves a control circuit for use in combination with an apparatus having a hydraulically operated work arm, such as a backhoe machine, for which there are desired arm positions, such as an “over center” transport position.
The present invention can be applied to any hydraulically operated articulated work arm in which it is necessary to reverse the flow of fluid through the hydraulic cylinder in order to achieve a desired position of the work arm. The control circuit that is used in combination with the apparatus comprises a valve, preferably a solenoid valve, a source of electricity for operating the solenoid valve, and a switching mechanism. The solenoid valve is operably connected with the work arm hydraulic operating system.
The switching mechanism is electrically connected in series between the electrical source and the solenoid valve in order to control operation of the solenoid valve. In operation, the solenoid valve is either in a closed or open position and therefore either prevents or permits the flow of hydraulic fluid into the head side of the cylinder. If the solenoid valve is configured to be in a “closed” position when there is no electrical flow, when the switching mechanism is activated to permit the flow of electricity to the solenoid valve, the solenoid valve will change to an “open” position so that hydraulic fluid can flow to the head side of the cylinder. In one embodiment of the present invention, the work arm hydraulic operating system comprises one or more supply lines leading to the work arm. The solenoid valve is then positioned between the supply lines to control the flow of hydraulic fluid.
The switching mechanism of the invention includes a first manually actuated operator switch and a second position actuated switch connected serially with the first switch. The position actuated switch is located remotely from the manually actuated operator switch. The position actuated switch is in an operative position associated with the work arm and responsive to the position of the work arm so that electricity will flow to the solenoid valve when the first manually actuated operator switch is closed and the work arm is located at a preselected position. In one embodiment of the invention, the second position actuated switch is located on the work arm. While the position actuated switch can be set to respond to any preselected position of the work arm, in a preferred embodiment of the invention, the position actuated switch is indexed to a vertical position of the work arm. In applications where the position actuated switch is indexed to the work arm's vertical position, the work arm can be pulled into the “over center” or transport position.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and provided for purposes of explanation only, and are not restrictive of the invention, as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate the preferred embodiment of the invention, and together with the description, serve to explain the principles of the invention.
FIG. 1
is a side elevation of a backhoe machine that is in an operating position.
FIG. 2
is a side elevation of a backhoe machine that is in transition between and operating position and a transport or carry position.
FIG. 3
is a side elevation of a backhoe machine that is in an “over center” or transport position.
FIG. 4
is a schematic drawing of the control circuit of the invention that can be used in combination with a backhoe-type machine.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Reference will now be made in detail to the present preferred embodiment of the control circuit of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference characters will be used throughout the drawings to refer to the same or like parts.
The present invention is directed to a combination of an apparatus having a hydraulically operated work arm and a control circuit. The work arm of the apparatus has a range of motion in which it can be operated to be positioned at various desired locations. In a preferred embodiment of the invention, the apparatus is a backhoe-type machine where it is advantageous to place the work arm into an “over center” position for transportation.
The present invention is applicable to any apparatus having a hydraulically operated work arm. The present invention is particularly applicable to providing an improved method for achieving a preselected location of the work arm.
FIG. 1
is a side elevation of one type of apparatus having a hydraulically operated work arm, namely a backhoe/loader machine
100
. A backhoe/loader machine
100
includes an operator's compartment
130
, a loader
120
, and a backhoe
140
. In a typical backhoe/loader machine
100
, the weight is unevenly distributed. The backhoe
140
portion of the machine
100
is disproportionately heavy and causes shifts in the center of gravity rearwardly away from the operator's compartment
130
when extended. The off-center weight distribution of the machine
100
makes ground transportation of the machine
100
more difficult. For example, steering control is diminished and the ride is uncomfortable at typical road speeds.
For transportation purposes, the weight distribution of the machine
100
is improved by moving the backhoe
140
weight closer to the center of the machine
100
. By moving the backhoe
140
closer to the operator's compartment
130
, the center of gravity for the machine
100
is shifted forwardly and it is not necessary to add weight to the front wheels
110
to counter balance the weight of the backhoe attachment. As a result, the machine
100
becomes more maneuverable, more stable on the road, and better able to negotiate difficult terrain. The different locations of the backhoe
140
in relation to the operator's compartment
130
between the operating and transport positions are depicted in
FIGS. 1 and 3
, respectively.
The transport position of the backhoe
140
can be described as an “over center” position because the cylinder
150
is moved beyond its shortest length and the backhoe
140
is brought toward the operator's compartment
130
. A hydraulically operated lift cylinder
150
is typically used to lift the work arm
145
of the backhoe
140
upwardly from its operating position by rotating about a pivot point
160
. As the work arm
145
is lifted toward its vertical position, the lift cylinder
150
shortens. The direction of flow of hydraulic fluid is such that the piston of the lift cylinder
150
moves into the cylinder portion, toward the head side
170
of the cylinder. As the work arm
145
of the backhoe
140
moves toward a vertical position, as depicted in
FIG. 2
, the lift cylinder
150
approaches its shortest length. In order to bring the work arm
145
into an “over center” position, the flow of hydraulic fluid within the lift cylinder
150
must be reversed so that the length of the lift cylinder
150
can increase as the work arm
145
is pulled past the vertical position and toward the operator's compartment
130
.
Presently, in order to bring the work arm
145
into the over center position, the operator of the machine
100
must operate the lift cylinder
150
in such a way that the flow direction of hydraulic fluid is reversed at precisely the right time. This method can be difficult for new or infrequent operators of the machine
100
. First the operator must initiate the lift cylinder's
150
lifting of the work arm
145
upwardly toward a vertical position. As the work arm
145
approaches a vertical position and when the lift cylinder
150
has its shortest length, the operator must quickly reverse the direction of hydraulic fluid flow in the lift cylinder
150
in order to force the lift cylinder
150
to begin to lengthen again and to move the work arm
145
into the over center position. If the operator's timing is off, the lift cylinder
150
will stop and not move the work arm
145
into the “over center” position. The procedure must then be repeated.
In order to overcome the deficiencies of the existing method, the present invention applies a control circuit to automatically sense when the work arm
145
is in its vertical position, or in any other preselected position, to automatically reverse the direction of the lift cylinder
150
. A schematic representation of a preferred embodiment of the control circuit of the invention is depicted in FIG.
4
.
The control circuit
300
includes a solenoid valve
180
that is operably connected with the hydraulic operating system of the work arm
145
and a source of electricity
210
for operating the solenoid valve
180
. The control circuit
300
further includes a switching mechanism
220
that is electrically connected in series between the electrical source
210
and the solenoid valve
180
in order to control the operation of the solenoid valve
180
. The switching mechanism
220
includes a first manually actuated operator switch
190
and a second position actuated switch
200
. The second position actuated switch
200
is connected serially with the first manually actuated operator switch
190
. The position actuated switch
200
is physically located away from the manually actuated operator switch
190
and is in an operative position associated with the work arm
145
and responsive to the position of the work arm
145
. The position actuated switch
200
is then able to connect the electrical source
210
to the solenoid valve
180
when the operator switch
190
is closed and the work arm
145
is located at a preselected location, such as vertical.
In a preferred embodiment, the solenoid valve
180
is positioned between the hydraulic fluid supply lines that lead to the lift cylinder
150
. The operator switch
190
, which is in series with the solenoid valve
180
, is located conveniently to the operator, such as being located in the operator's compartment
130
. The operator switch
190
can be in the form of an actuator button or a similar device. The position actuated switch
200
is located so as to be associated with the work arm
145
. In one embodiment, the position actuated switch
200
is located at the base of the lift cylinder
150
and is indexed to detect a vertical position of the work arm
145
. In order to move the backhoe
140
from an operating position to an “over center” position, the operator activates the hydraulic operating system such that the lift cylinder
150
begins to shorten and to upwardly move the work arm
145
. At the same time that the lift cylinder
150
is activated, the operator depresses the actuator button, or other device, of the operator switch
190
. When the work arm
145
reaches a vertical position, the position actuated switch
190
completes the control circuit
300
. Once the control circuit
300
is complete, the electrical source
210
becomes connected to the solenoid valve
180
and, therefore, opens the solenoid valve
180
. When the solenoid valve
180
is open, both ends of the lift cylinder
150
are open to the hydraulic fluid supply source. This permits pump flow and cylinder discharge flow to enter the head side
170
of the lift cylinder
150
and to push the piston away from the head side
170
of the lift cylinder
150
, thereby again increasing the length of the lift cylinder
150
. The inertia of the moving backhoe
140
and the pressure on the head side
170
carry the work arm
145
into the “over center” or transport position. Rather than having to reverse the direction of the lift cylinder
150
when the work arm
145
is precisely at the vertical position, the operator simply activates the lift cylinder
150
while simultaneously actuating the operator switch
190
.
FIGS. 1-3
depict the sequence of events between moving the backhoe
140
from an operating position depicted in
FIG. 1
to a transport or latched position in FIG.
3
. In
FIG. 1
, the backhoe
140
is in the position in which it would be used by the operator for its intended function. The lift cylinder
150
is fully extended and the solenoid valve
180
of the control circuit
300
is closed. When the job is completed or when it is necessary to transport the machine
100
, the operator will want to move the backhoe
140
into the transport or carry position. The operator begins the process of moving the backhoe
140
by activating the lift cylinder
150
to move the backhoe
140
upward. As the lift cylinder
150
moves the work arm
145
of the backhoe
140
upward, the length of the lift cylinder
150
decreases as it rotates upwardly about the pivot point
160
. At the same time that the operator activates the lift cylinder
150
, the actuator button is manually operated to enable the system.
FIG. 2
represents the position of the backhoe
140
when the work arm
145
is at or near vertical position. The lift cylinder
150
is at its shortest length and, therefore, the piston is completely inside the cylinder. If the backhoe
140
were left in this position for transportation, the machine's
100
center of gravity would be weighted toward the backhoe
140
. In order to move the center of gravity toward the center of the machine
100
, the front wheels
110
would have to be weighted. This is undesirable as it has negative consequences on the transportability of the machine
100
as described herein. At the point that the work arm
145
reaches the vertical position depicted in
FIG. 2
, the position actuated switch
200
, which has been indexed to the vertical position of the work arm
145
, is activated. The position actuated switch
200
can be indexed to any desired position of the work arm
145
; for the present application, indexing to the vertical position is desirable. Activation of the position actuated switch
200
results in the control circuit
300
being completed so that electricity can flow from the electrical source
210
to the solenoid valve
180
. As a result, the solenoid valve
180
opens which permits pump flow and cylinder discharge flow of the hydraulic fluid to enter the head side
170
of the lift cylinder
150
.
With the solenoid valve
180
open, the lift cylinder
150
begins to extend its length again, and the work arm
145
pivots past a vertical position toward the operator's compartment
130
. The inertia of the work arm
145
and the pressure on the head side
170
of the lift cylinder
150
carry the backhoe
140
into the transport or latched position. The transport position of the backhoe
140
is depicted in FIG.
3
. The transport position is characterized by the work arm
145
being “past” or “over” the vertical or center position. In this “over center” position, the machine's
100
center of gravity is closer to the operator's compartment
130
. By moving the center of gravity closer to the operator's compartment
130
, the need for adding weight to the front wheels
110
is eliminated. In the “over center” position, the machine
100
is more maneuverable and better able to negotiate difficult terrains at road speeds.
If the operator switch
190
is not activated, the backhoe
140
has to be put into the “over center” position by the method currently used in which the operator must decide when to reverse the direction of the lift cylinder
150
. If the position actuated switch
200
or the operator switch
190
are activated independently, there is no effect on the operation of the backhoe
140
.
Although reference has been made to the use of the present invention in conjunction with bringing the backhoe portion of a backhoe/loader machine into an “over center” position for the purpose of explanation, it is understood that alternative uses for the control circuit of the invention exist. It also will be apparent to those skilled in the art that various modifications and variations can be made in the design and construction of the control circuit without departing from the scope or spirit of the invention.
Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the invention being indicated by the following claims.
Claims
- 1. In combination with an apparatus having an articulated work arm that is movable to a transport position and a hydraulic operating system therefore, a control circuit comprising:a solenoid valve operably connected with the work arm hydraulic operating system; a source of electricity for operating the solenoid; and a switching mechanism electrically connected in series between the electrical source and the solenoid to control operation thereof, said switching mechanism including a manually actuated operator switch and a position actuated switch located remotely from the operator switch in an operative position associated with the work arm and responsive to the position of the work arm so as to connect the electrical source to the solenoid valve when the operator switch is closed and the work arm is at a preselected position.
- 2. The control circuit of claim 1 wherein the work arm hydraulic operating system comprises supply lines leading to the work arm and the solenoid valve is positioned between the supply lines.
- 3. The control circuit of claim 1 wherein the position actuated switch is located on the work arm.
- 4. The control circuit of claim 1 wherein the preselected location of the work arm is the vertical position.
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
5007544 |
Saotome et al. |
Apr 1991 |
|