Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
Background of the Inventlon `
A. Field of the Invention
This invention relates to the field of towed
vehicles which have many hydraulically operated functions and
ln particular, an electrohydraulic system for those hydraulic ~ ```
functions.
B. Prior Art
Towed vehicles are well known in the art in
which specific functions are carried out hydraulically. In
particular, towed farm vehicles may have from three to eight
and even more functions each of which is hydraulically powered.
For example, the "Stackeze" made by the Haybuster Corporation ` `
handles hay and has five functions and thus requires a control
valve assembly with five hydraulic control valves and five
control handles. Another towed farm vehicle, the "Mark 660
Potato Harvester" made by the Lockwood Corporation may have
up to eight ~unctions thus requiring at least one control
valve assembly comprised of eight hydraulic control valves
and eight control handles.
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In such towed vehicles, the control valve assembly
may be secured to the towed vehicle. Thus, an operator
additional to the tractor operator is required to ride on
the towed vehicle in order to actuate the control handles.
On the other hand, the control valve assembly may be unbolted
from the towed vehicle and attached to the tractor so that
the control handles may be close to the tractor operator.
Thus, it has been attempted to position the control valve
assembly convenient to the tractor operator so that he
could not only drive the tractor but also operate the controls
of the valve assembly.
However, such "attachable" control valve assemblies
have left much to be desired since each valve assembly
requires many hydraulic lines between valve assembly and towed
vehicle. According, with two hydraulic lines required for
each function, the resultant valve assembly has been unwieldy
as well as being a source of noise and dangerous hot oil close
to the driver. In addition, the control handles have not really
been convenient for manipulation from the driver's seat of thè
tractor. This is a particularly important problem since many
arm tractors now have fully enclosed cabs to protect the
operator from noise, dirt, heat, cold, etc. As a result, it
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has been extremely difficult for the operator to reach around
out of the door of an enclosed cab in an attempt to operate
the control handles. In some cases, the operator has had to
; open a window of the cab or make special large openings in
the cab for this purpose. However, all of this defeats the `
- purpose of an enclosed cab to provide the operator with a
controlled and protected environment.
In an attempt to overcome these difficulties, it
has been known to install the control valve assembly inside
the cab. However, this is very undesirable. Such an installa-
tion requires that all the hydraulic hoses be brought into
the cab. This almost completely defeats the controlled
environment of the cab by bringing in heat from hoses carrying
hot oil and hydraulic noise from the hydraulic system~ Thus,
there is the unacceptable danger to the operator ~rom hot
oil leaks which may be in violation of proposed OSHA regulations.
~ further problem arises whether the valve assembly
is within the cab or secured to the tractor outside the cab.
Specifically, when the towed vehicle is rèleased, the valve
assembly must be unbolted, removed from the tractor and stowed `
on the towed vehicle. Thus there has been required a very heavy
transfer of a valve assembly and hydraulic lines with the
resultant breakage and crimping of the hydraulic lines.
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Summary of the Invention
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A towed vehicle having a frame and hydraulic
functions powered by a plurality of hydraulic devices to be
controlled. An electrohydraulic valve assembly is hydraulically
coupled to the hydraulic devices and is rigidly secured to
the frame of the towed vehicle. A switching assembly having
a plurality of switches is adapted for electrically switching
the valve assembly. An electrical cable is coupled between "`
the switching assembly and the valve assembly secured to the
vehicle frame. The switching assembly is disposed within
the cab to allow easy access of the plurality o switches
to the operator of the tractor while avoiding hydraulic oil
lines and valves within the cab and at the same time allowing
the towed vehicle to be easily disconnected from the tractor.
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Brief Description of the Drawings
Fig. 1 shows a portion of a towed vehicle and
a tractor pulling it;
Fig. 2 lllustrates in more detail the electro-
hydraulic valve assembly and switching assembly shown in
Fig. l;
Fig. 3 schematically illustrates the individual
switches of the switching assembly as coupled to the
electrohydraulic valve assembly of Figs. 1 and 2;
Fig. 4 schematically illustrates ~he hydraulic
circuit of the electrohydraulic valve assembly of Figs. 1-3;
and
Figs. 5 and 6 illustrates in detail a normally
open solenoid valve and a closed center screw adaptor shown
in Flgs, 1-4.
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Detailed Description
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Referring now to Fig. 1, there is shown a tractor
10 pullîng a towed vehicle 12 having an electrohydraulic
valve system including a valve assembly 15 which operates
and controls all of the hydraulically powered functions of
the towed vehicle.
Towed vehicle 12 may be any conventional towed
farm vehicle such as a "Stackeze 1600" which picks up hay
by means of a hay pick up 18, compresses the hay and efect-
ively forms the compressed hay into a stack on the rear
portion of vehicle 12 (not shown). Towed vehicle 12 accom-
plishes its overall stacking operation by means of five
~, hydraulic functions. Thus, valve assembly 15 requires five
valve circuits 15a-15d for controlling the Eive hydraulic
functions. As illustrated, vehicle 12 has an elongated
frame 20, a hitch bar 22 secured to ~rame 20 and power
apparatus 24 for receiving the power take off (PT0) of tractor
10. ,~
Tractor 10 is a conventional farm tractor havlng a
rear axle 26 and rear wheel 28. Tractor 10 may have a Eully
enclosed cab 30 or body which provides the tractor operator ~ ~
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with protection from noise, dirt, shock, vibra~ion, heat and
cold as well as dust, wind and other adverse weather condi~ions.
Thus, the windows, doors and body of cab 30 are tightly sealed
and the atmosphere o~ the cab is pressurized and filtered.
It is in this way that dust and powdery snow are kept from
the cab's interior. Further, a heater and an air conditioner
allow the operator to adjust the cab's temperature and humidity.
With the further addition of padding and vibration protection,
there is ~ormed a controlled environment for the operator.
Tractor 10 includes a conventional hitch 32 ~or
at~achment to hitch bar 22 and a draw bar 34 is help~ul with
wind-span towed equipment. Ftlrther, tractor 10 has a PTO
assembly comprising a power shaft 36 which is coupled to
assembly 24 o~ towed vehicle 12. In addition, tractor 10
lS has a conventional hydraulic remote cylinder outlet 38
coupled to a pump line 40 and a drain line 41.
As shown in Figs. 1, 2 and 4, pump line or hose 40
and drain line or hose 41 are connected to electrohydraulic `
valve assembly 15 which is secured to an upper portion o~
rame 20 as illustrated. Valve assembly lS i9 coupled by
linQs and hoses in conventional manner to the hydraulic ;;
cyllnder~ (not shown) of towed vehicle 12 which operate the ~
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five functions of unload~ dump, pick up, swing and boom lift.
It will be understood that these hydraulic functions are
examples of hydraulic functions which could be used on a towed
vehicle.
Valve assembly 15 is controlled by electric switch
assembly 44 which is not secured to the towed vehicle but is
mounted within cab 20. For example, assembly 44 may be formed
of a rectangular housing bolted within the cab in a position
where it would be most comfortable for actuation by the
tractor operator. From assembly 44, a connector 46 leads to
a cable 48 which extends below the assembly through cab 30
and terminates in a connector assembly 50 at the rear of
tractor 10 adjacent outlet 38. A seal is used to plug the
gap around cable 48 after it has been installed to maintain
L5 the integrity of cab 30. Assembly 50 receives a plug-in
connector 51 which is coupled by means of a cable 52 to the ~:
valve assembly 15. In this manner, switch assembly 44 is
permanently connected within cab 30 and when towed vehicle 12
is to be disconnected from tractor 10, it is only necessary
to remove connector 51 and hoses~40, 41 from outlet 38 in
order to discom~ect the electrohydraulic system between tractor
and towed vehicle. .
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It will now be understood how the integrity and the
controlled environment of fully enclosed cab 30 may be main-
t'ained while still providing for easy and convenient operation
of towed vehicle 12 from within the cab. In this way, there
is provided electrically remote actuationof the towed vehicle
by means of easily reached electric switches of assembly 44
without the necessity of bringing hydraulic oil and valves
within the cab. An electrohydraulic valve system has been
provided for an attachment converting a farm tractor to a
front end loader,
Switch assembly 44 is grounded to the chassis or
frame of tractor 10. In addition, the positive side (V~) of
tractor battery 54 is coupled to assembly 44 and in conventional ~`
manner, the negative side o~ the battery is coupled to chassis
ground. Since towed vehicle 12 may or may not have a ground
connection to tractor 10, the ground for valve assembly 15 is
returned by way of cables 52 and 48 to the chassis ground at
switch assembly 44. ``
It will be understood that instead of being ~ixed
within cab 30, switch assembly 44 may be releasably secured
with~n the cab in the form of a wall mount wlth cable 48 belng ~ ~`
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a flexible extension cable extending therefrom. In this way,
assembly 44 may be moved anywhere in the cab. Further, cable
48 may itself directly extend to assembly 15 without the use `;
of connectors 50, 51 and pass through a sealed opening in
the cab. Accordingly, assembly 44 may then be removed from
the cab and used in the cab of another tractor.
Valve assembly 15 operates in the following manner
under the control of switch assembly 44 as illustrated in
Figs. 2-4. Valve assembly 15 comprises a stacked valve
assembly comprising solenoid valves 60-69 and pilot operated
Eour way spool valves 70-74. As shown, valve assembly 15
comprises six valve sections 15a-f which have been stacked
together. Each of the valve sections may comprise one or - `
two solenoid valves and a spool valve. It is in this manner
that the unitary valve assembly 15 may be easily mounted on
towed vehicle 12 in the manner previously described. It will
; be understood that such a unitary assembly may be provided
by means other than a stacked valve assembly such as a single
castin~ within which all o~ the valves have been assembled.
~0 As shown in Fig. ~, an hydraulic fluid pump in
~rac~or 10 is indicated as pump 55 while the drain is indicated
a~ re9ervoir 56. Accordingly, pump and drain lines 40, 41 ~rom
pump 55 and reservoir 56 are applied to assembly 15.
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Lines 40, 41 lead to valve section 15f which
comprises a two stage valve 58a-b which operates as illustrated
in Fig, 4 if tractor 10 uses an open center system. With
such an open center system, valve assembly 15 requires a
normally open conditi.on as illustrated. In the event that
tractor 10 uses a closed center system, valve 58a-b may be `
made normally closed and inoperable in the field by means of
a screw adapter 88 shown in Figs. 5, 6 and later described
in detail. Valve 58a-b may be similar in operation and
construction to a two stage valve shown and described in :
U.S. Patent No. 3,799,497. ~`
One terminal of the coil of each oE solenoid val~es
58a-b and 60-69 is connected to ground and the other terminal ;
of each solenoid valve is selectively connected by way of
cables 52 and 48 and switch assembly 44 to source V~ of
electrical supply. Upon actuation of one or more of
switches 80-84 as shown in Fig. 3, source V~ is applied to
selected ones of the solenoid valves for actuation thereo~.
Switches 80-84 are conventional spring centered double pole
double throw switches in which the left switch section~
actuates valve 58a while the right switch section actuates
the solenoid valves of a respective valve section 15a-e.
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Specifically, the left contact of the right section
of each of switches 80-84 are respectively coupled to the
coils of hydraulic valves 60, 62, 64, 66 and 68. The right
contact of the right section of switches 80-84 are respect-
ively connected to valves 61, 63, 65, 67 and 69. Both contacts
of the left section of switches 80-84 are connected to valve
58a. Accordingly, when any one or more of switches 80-84 are
moved to the left, valve 58a is energized as well as respective
hydraulic valves 60, 62, 64, 66 and 68. On the other hand,
when any one or more of switches 80-84 are moved to the right,
hydraulic valve 58a is also energized as well as respective
valves 61, 63, 65, 67 and 69.
In operation, switch 80 may be manually pushed in
a direction as illustrated to the left and thus potential V+
is connected to the coils of solenoid valves 58a and 60.
Wlth its coil energized, valve 58a closes thereby closing its
second stage 58b and in this way pump line 40a is pressurized.
Valve 60 acting as a pilot valve, opens thereby pressurizing
the le~t side of spool valve 70 and applying pressure to the
~0 le~t side of the cyllnder. The cylinder of valve 70 i9
normally sprung to the center position with all ports blocked.
Thu9, with it9 left side pressurized, the cylinder moves to ~ ~
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the right. Accordingly, pressure is supplied to line 76 and
tank to lines 77. In this manner, the unload cylinders
connected to lines 76 and 77 are actuated ~or an unload
function.
With switch 80 maintained in the le~t position,
pressure continues to be applied to line 76 until the switch
is released and returns to its spring center position. Then, ~ -
the coils of valves 58a and 60 are deenergized and valve 70
returns to its normal position in which all of its ports are
blocked thereby maintaining the position o~ the unload
cylinders connected to lines 76, 77.
In order to reverse the unload cylinders, switch 80
is moved to its illustrated right hand position.` In the
manner previously described, valve 58a-b is energized and
moves to its closed position. In addition, solenoid valve
; 61 is energized and thus the right hand side of spool valve
70 is pressurized moving the cylinder to the left. Accordingly,
the lines are reversed from that previously described with
lines 77 having pressure applied thereto and tank is applied
- 20 to line 76. This condition is maintained as long as switch 80
is maintained in the right hand position. At the time switch
80 is released to its spring center position, the unload
cylinders are maintained in their position.
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The remaining hydraulic circuits of valve sections
15b-e each operate in similar manner under the control of
their respective switches 81-84. Since such operation is
similar to that described for section 15a, it is not
necessary to describe this operation in detail.
Referring now to Fig. 5, there is shown in detail
valve 58a which is similar to the single stage normally opened
solenoid operated valve shown in U.S. Patent No. 3,765,644
and similar to the first stage valve shown in U.S. Pa~ent No.
3,799,497. Accordingly, with a screw 86 threadedly engaged
in an upper section of housing or stack 87 a plunger 90 is
not actuated and first stage 58a operates as a normally
open valve for u~e with a tractor's open center system.
i However, in the event that tractor 10 uses a closed
center system, valve 58a-b is made normally closed by means
of the closed center ~crew adapter 88 shown in Fig. 6 which
replaces screw 86. Screw adapter 88 comprises a normal screw
threaded portion 88a and a reduced diameter extension 88b
extending from the end of threaded portion 88a remote from
head 88c. Extension 88b is effective to engage and move
downwardly adjusting plunger 90 when screw adapter 88 ls
manually screwed downwardly into the upper section o~ stack
87. A spring 95 i9 disposed within cavity 91 and extends
between the lower section of plunger 90 and an upper surface
of armature 94. Accor~ly, as plunger 90 moves downwardly,
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.spring 95 is effective to downwardly bias armature 93. In
turn, armature 93 applies downward pressure on a spring
biased poppet 9Z thus to close poppet plug 97 in orifice 98.
Spring 95 is used to transmit the force from plunger 90 to `
armature 93 in order to avoid damage to plug 97 and orifice
98 in the event that screw adapter 88 is excessively screwed
into stack 87.
It is in this way that first stage 58a and thus
second stage 58b may be made normally closed and inoperable
in the field by means of replacing screw 86 with a screw
adapter 88.
It will be understood that further modifications
may be made. For example, switch assembly 44 may contain ;~ `
electronic subassemblies for purposes of automated control. .,
Thus, certain functions may be programmed to operate in a
desired sequence. When a bail reaches a certain height, ; ~
another function and then another function may come into `
effect~ `'; ~;
In addition, an additional switch assembly (not~ ;`
shown) may be provided which ls coupled by means of suitable
connectors and a cable to switch assembly 4~. In this
mannar, tha additional switch assembly may be mounted on the
laft side o~ cab 30 for example while assembly 44 may be
secured to the right side.
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