US 3823647 A
An electromagnetic bucket positioner includes an electromagnet disposed to selectively latch, when energized, a control valve of a bucket positioning system. A normally-open switch is included in the system, and is adapted for closure via selected movement of a manually operable control lever, thereby energizing the electromagnet to latch the control lever in the select position. A normally-closed switch is disposed in series with the normally-open switch, and is adapted to be opened upon selected translation of the cylinder rod of the associated hydraulic cylinder, to thus interrupt current flow to the electromagnet, to de-energize same and release the control lever. The control valve returns to a neutral position, stopping the flow of hydraulic fluid to the respective cylinder, to stop further movement, tilt, etc., of the vehicle bucket. An electronic relay circuit may be included to introduce current to the electromagnet when energized via closure of the switches. In the latter embodiment, the relay circuit is de-energized after the electrical circuit is interrupted by opening the respective normally-closed switch.
Description (OCR text may contain errors)
United States Patent 1191 Campbell et al.
[ ELECTROMAGNETIC BUCKET POSITIONER FOR HEAVY EQUIPMENT VEHICLES AND THE LIKE Inventors: Trevor G. Campbell, Peoria; James W. Russey, Decatur, both of 111.
Assignee: Caterpillar Tractor Co., Peoria, Ill.
Filed: Aug. 29, 1972 Appl. No.: 284,491
Int. Cl. FlSb 13/16 Field of Search ..-9l/358 A, 363 R, 413, 414; 214/762, 763, 764
References Cited UNITED STATES PATENTS 1/1970. Shook et al 214/762 8/1970 Fuzz ell 214/762 5/ 1 972 5 9. 3 1 1;- L. c :,-.2;L f 6/1972 SchneiderT. 91/358 A US. Cl 91/358 A,'91/413, 91/414,
1451 July 16, 1974  ABSTRACT An electromagnetic bucket positioner includes an electromagnet disposed to selectively latch, when energized, a controlvalve of a bucket positioning system. A normally-open switch is included in the system, and is adapted for closure via selected movement of a manually operable control lever, thereby energizing the electromagnet to latch the control lever in the select position. A normally-closed switch is disposed in series with the normally-open switch, and is adapted to be opened upon selected translation of the cylinder rod of the associated hydraulic cylinder, to thus interrupt current flow to the electromagnet, to de-energize sameand release the control lever. The control valve returns to a neutral position, stopping the flow of hydraulic fluid to the respective cylinder, to stop further movement, tilt, etc., of the vehicle bucket. An electronic relay circuit may be included to introduce current to the electromagnet when energized via closure of the switches, In the latter embodiment, the relay circuit is de-energized after the electrical circuit is interrupted by opening the respective normally-closed switch.
8 Claims, 5 Drawing l ligures v I, O 82 as 9 YH PAIENIED Jun sum ELECTROMAGNETIC BUCKET POSITIONER FOR BACKGROUND OF THE INVENTION 1. Field The invention relates to a component positioner for heavy equipment vehicles and the like, which automatically positions a bucket, blade, etc., of the vehicle.
2. Prior Art Various types of control systems have been contemplated for providing automatic positioning of, for example, the bucket on a loader vehicle, etc. Typically, such positioning systems are hydraulically, mechanically, or electrically operated.
Hydraulic positioning control systems suffer from bucket control problems when malfunctions occur in the hydraulic system. For example, a leak in the slave cylinder or the hydraulic circuit can cause bucket drifting whichranges from slight movement to a drifting which simulates a slow dump. A broken supply line almost completely incapacitates the positioning control system. External repairs are time-consuming, particularly if the line to the tank has to be replaced. If an internal repair or adjustment has to be made, it is necessary to drain the hydraulic tank, thus resulting in excessive down-time. A
Electrical positioning control systems overcome most of the inherent problems of the above-identified hydraulic systems, in that they are more reliable, more readily serviced, and are external and thus independent of the main hydraulic apparatus. However, most electrical positioning systems utilize microswitches mechanically coupled for actuation to cams, recessed rods, etc., which in turn, are attached to the tilt positioning hydraulic cylinder to thus indicate the position of the bucket or vehicle component. Thus, the combi- I nation is subject to wear, dirt, vibration, etc., common to earh-moving apparatus, with the associated maintenance and break-down problems.
Also typical of prior art electrical positioning systems, are those utilizing a detent mechanism as an integral part of the control valve, which includes aspringloaded latching system to retain the control valve in a preselected position. Release of the control valve is effected via a solenoid, which acts against the springs to release the latch mechanism and thus the control valve. Such systems require energization of the solenoid in order to release the control valve.
SUMMARY or THE INVENTION The invention provides an improved electromagnetic position control system for controlling the tilt, position, orientation, etc., of a selected component on a heavy equipment vehicle. To this end, a hydraulic cylinder is coupled via an associated cylinder rod to a bucket or vehicle component. An electromagnet is disposed to latch a control valve in a selected operating position when the control valve is moved byv the operator by means of a control lever. A first normally-open switch is disposed for closure when the lever is moved to the selected position and is serially coupled to a second normally-closed switch disposed on the hydraulic cylinder. The switches are actuated by application thereto of a magnetic field. Means for generating the respective magnetic fields are secured to the control lever, and
also disposed for reciprocation with the hydraulic cylinder rod.
In operation, upon dumping the bucket contents, the operator moves the lever to the selected (rack-back) position, which causes energization of the electromagnet via closure of the first normally-open switch by the magnetic field secured to the lever. At such times as the cylinder rod moves its associated magnetic field adjacent the second normally-closed switch, the second switch is opened to interruptthe current to the electromagnet, whereupon the control lever is released to allow the control valve to seek its neutral position. Since fluid is no longer delivered to the hydraulic cylinder, thebucket stops in the selected'position ready for the next load cycle.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a perspective depicting one embodiment of the invention combination for positioning a vehicle component.
DESCRIPTION OF THE PREFERRED EMBODIMENTS It is to be understood that although the invention is 'herein described with respect-to the positioning of a bucket of a loader vehicle, the combination may be utilizedto position, orient, tilt, etc., any of various known components of various types of earth-moving apparatus, heavy equipment vehicles, etc. 7
Accordingly, referring to FIG. 1, there is shown a bucket positioner system in accordance with the invention combination, for automatically positioning a bucket of a loader vehicle so that it is level when lowered to the ground to allow loading the bucket. To this end, a single control lever 10 is adapted for movement fore and aft, as well as from side-to-side, to thus provide manually operable means for controlling both a bucket lift control valve 12 and a bucket tilt control valve 14. A fore and aft movement of the control handle 10, causes a lever 16 to pivot about a first axis 18, causing pivoting of an arm 19 secured to the lever 16, which in turn raises or lowers a control element 20 to actuate the lift control valve 12. Control valve 12 selecpled to a lever 28 and pivots the latter about a third axis 30 to thus raise or lower a control element 32 of the tilt control valve 14. A ferrous bar 34 and a permanent magnet 36 are attached to the pivotable end of the lever 28.
The bucket positioner of the invention includes an electrical circuit that acts as a detent for holding the tilt cylinder control valve 14 in the rack-back position until the bucket is level with the ground. The circuit utilizes two switches 38, 40, which are actuated by applying a magnetic field thereto. The switch 38 is normallyclosed and the switch 40 is normally-open, with both switches being placed in series with an electromagnet 42. A battery 44 is coupled from the switch- 38 to ground and serves as an energy source for energization of the electromagnet 42 when both switches 38, 40 are closed. The normally-open switch 40 is secured in the region of the control valve and lever l4, 10, to allow the ferrous bar 34 to pivot against the electromagnet 42 when the lever is moved to the rack-back position.
The normally-closed switch 38 is attached to a tilt cylinder 46 of the loader vehicle, adjacent the rear end of a tube 48, axially secured along the cylinder 46. A rod 50 has a first end slidably disposed in the tube 48 and a second end thereof integrally secured to the tilt cylinder rod 52. In addition, the first end of rod 50 has a small permanent magnet 54 disposed thereon for triggering the switch 38. Upon the extension or retraction of the tilt cylinder rod 52, rod 50, integral therewith,
' reciprocates through tube 48. The length of the rod 50 is such that the first end thereof extends slightly from the rear end of the tube 48 when the bucket is in a level ground position. Therefore, tube 48 and rod 50 also combine to form a visual bucket position indicator by which the operator may visually level the bucket if desired. However, as intended by the invention combination, automatic positioning of the bucket is preferable to allow the operator to divert his attention to other activity, such as backing-up, in order to save time during the loading cycle. a
In operation, with the loader bucket in the dump po-, sition, the operator desires to level the bucket when it is lowered to the ground so that it will be in the proper position to begin the next workcycle. To this end, the operator moves the control handle 10 to the rack-back position, which actuates the control valve 14, causing the tilt cylinder 46 to retract. Movement of control handlev 10 to the rack-back position, causes the lever 28 to pivot about axis 30, whereby permanent magnet 36 is brought into close proximity of and applies a magnetic field to the switch 40. This completes the circuit from ground through the battery 44, the normallyclosed switch 38, and switch 40 to the electromagnet 42, thereby energizing the latter. Electromagnet 42, in turn holds the lever 28 and thus lever 10 in the rackback position by means of the magnetic attraction bebucket is stopped in the selected level position, ready for the next load c'ycle.
Referring now to FIGS. 2-4, there is shown an alternative, more sophisticated, embodiment of the invention, including a bucket tilt and lift positioning system, having a solid state relay circuit and a mechanical control lever linkage mechanism, which inpart cooperates with the electronic circuit to provide the invention combination. Note that similar elements in the embodiment of FIG; 1 and that of FIGS. 2-4 are designated by the same numerals.
Accordingly, the single control lever 10 is adapted for fore-and-aft, as well as side-to-side movement. Lever 10 is operably connected during fore-and-aft movement, via a lift mechanical linkage mechanism 56 'to the lift control valve 12', and during side-toside movement via a tilt mechanical linkage mechanism 58 to the tilt control valve 14. The lift linkage mechanism 56 includes a bell crank 60, whichisprovided with an additional arm 62, and which controls the lift operation of the vehicle bucket, via the lift control valve 12 and tween the electromagnet 42 and the ferrous bar 34. If
desired, the operator may move the control valve 14 from the rack-back position by manually overriding the force of the electromagnet 42.
. As the bucket moves from the dump position to the rack-back position, the retraction of cylinder rod 52 causes the rod integral therewith, to slide rearwardly through the tube 48 until the permanent magnet 54 reaches a position directly adjacent the normallyclosed switch 38. Switch 38 then opens which interrupts current flow to the electromagnet 42 to allow the self-centering control valve 14 to move from the rackback position to a neutral center position, thereby interrupting flow of fluid to the tilt cylinder 46. Thus, the
a lift hydraulic cylinder 64. The arm 62 is provided with an angled flat surface 66 at its pivotable end. The bell crank 60 is coupled to the lift control element 20 via an adjustable rod 67.
The tilt linkage mechanism 58 includes a bell crank 68, which is also provided with an additional arm 70, and which controls the tilt: operation of the vehicle bucket, etc., via the tilt control valve 14 and the tilt hydraulic cylinder 46 (of for example FIG. 1). Arm 70, as best seen in FIG. 4, is also provided with an angled flat surface 72 at its pivotable end. The'bell crank 68 is coupled to the tilt control element 32 via an adjustwith a pair of angled flat surfaces 80, 82. The flat surfaces 80, 82 are oriented for confronting contact against the flat'surfaces 66 and 72 of arms 62 and respectively, upon pivotal rotation of the arms toward the core 78.
The electromagnet 42is energized via the electronic circuit shown in schematic in FIG. 2. The circuit includes the battery 44 of FIG. 1, a disconnect switch 84, and a fuse 86, serially connected from ground to a solid state relay 88. Relay 88 includes a PNP transistor 90, which, when turned on', supplies a positive bias to the base electrode of an NPN transistor 92. Transistor 90 is triggered upon application of a negative bias to the base electrode thereof, through completion of a circuit to ground through either of a pair of conductors 94 or 96 connected via a blade terminal 98. A conductor 100 couples the transistor 92 to the electromagnet 42 via a blade terminal 102.
The conductors 94 serially connect a first normallyopen proximity switch 104 and a first normally-closed proximity switch 106. The conductors 96 serially connect a second normally-open proximity switch 108 and pairs of switches, provide two parallel circuits to ground corresponding to respective lift and tilt positioning systems, for triggering the transistor 90 via application of the negative bias thereto, as previously discussed. i
The circuit further includes permanent magnets for triggering the proximity switches 104-110. A first permanent magnet 112 is attached to the bell crank 60 for pivotal movement therewith. The proximity switch 104 is secured on the support 76 in a preselected position, whereby it is aligned with the magnet 112 when the surface 66 of the arm 62 contacts the surface 80 of the core 78 of electromagnet 42. A second permanent magnet 114 is secured for pivotal movement with a lift arm 116 coupled to the lift hydraulic cylinder 64. The normally-closed switch 106 is secured to a lift tower 118 of the vehicle in a selected position whereby it is aligned with the magnet 114 when the lift arm 116 raises the bucket to a predetermined height.
A third permanent magnet 120 is securedto the tilt linkage mechanism 58, as on one of the arms of the bell crank 68, for pivotal movement therewith. The normally-open switch 108 is secured to the support 76 in a preselected position whereby it is aligned with the magnet 120 when the surface 72 of arm 70 contacts the surface 82 of core 78 of the electromagnet 42. Fourth and fifth permanent magnets 122 and 124 are secured to an indicator rod 50 coupled to the cylinder rod 52 of the hydraulic cylinder 46. The positions of the magnets 122, 124 on indicator rod 50 are indicative of the position of thecylinder rod 52 and thus of the tilt of the bucket (not shown) to which cylinder rod 52 is coupled. The normally-closed switch ll0is secured to the tilt cylinder 46 in preselected position, whereby it is in register with the magnet 122 when the bucket is in a level orientation with respect to the ground. The magnet 124 is spaced a predetermined distance from magnet l22 on the indicator rod 50, whereby it is in register with the switch 110 when the bucket is in the full rackback orientation.
As shown schematically in FIG. 2, fluid pressure is applied to the control valves 12, 14 via the hydraulic fluid pump and tank 22, as depicted in FIG..1. The lift control valve 12 directs hydraulic fluid via conduits 126, 128 to the reciprocatable lift hydraulic cylinder 64, which in turn is pivotally coupled via its cylinder rod to the lift arm 116 for raising and lowering the vehicle bucket (not shown). The tilt control valve 14 directs hydraulic fluid via conduits 130, 132 to the reciprocatable tilt hydraulic cylinder 46, which is pivotally connected via its cylinder rod 52 to linkage (not shown) for pivotally adjusting the tilt orientation of the vehicle bucket.
The operation of the bucket tilt and lift systemof FIGS. 2-4 is similar to that of the tilt system described with reference to FIG. 1. For example, assuming that the lift arms 116 are raised and the bucket is in the dump position orientation, the tilt hydraulic cylinder is substantially extended and the magnetl22 is in a position away from, and to the right of, the normally-closed switch 110. Movement of the control lever to the rack-back position until the arm 70 contacts the electromagnet 42, actuates the tilt control valve 14 to retract the rod 52 of the hydraulic cylinder 46. When the arm 70 contacts the electromagnet 42, the latter is energized via completion of the respective circuit, by the simultaneous closure of the switch 108 via the magnet 120. Since tilt control valve 14 is now held in a detent position, cylinder 46 will continue to retract until the magnet 122 moves adjacent to the switch 110. Thereupon, switch 110 opens to de-energize the electromagnet 42, which releases the arm 70. This allows the tilt control valve 14 to return to its neutral or hold position, thereby automatically positioning the bucket in the desired level orientation.
It may be seen, that .while the valve 14 is detented in the rack-back position, the operator is free to direct his attention to lowering the bucketby appropriate actuation of the lift control valve 12 via the control lever 10. Upon obtaining a load in the bucket, the operator may have both the control valves 12, 14 held in the detent positions by the manipulation of the lever 10 to both the full rack-back and the raise positions to bring the arms 62 and 70 into contact with the electromagnet 42. As previously noted, the electromagnet 42 is energized by closure of either or both of the normally open switches 104, 108 via the presence of the respective permanent magnets 112, 120.
Since tilt hydraulic cylinder generally bottoms out before the lift arms 116 reach their maximum pivotal rotation, magnet 124 is positioned to trigger the normally-closed switch 110 when the tilt hydraulic cylinder is fully retracted. Since the electromagnet 42 is still energized via thecontinued closure of the switch 106, control valve 14 is still held in a detented position. Thus, to avoid the continued operation of the hydraulic system over the relief valve pressure because of the continued actuation of the valve 14 after the tilt cylinder 46 is fully extended, a parallel hydraulic fluid flow system such as that of FIG. 5, may be employed.
To this end, the flow of hydraulic fluid from the pump 22 is divided into three flow passages, corresponding to conduits 134, 136 and 138, at a junction 140. The conduit 134 diverts fluid back to the tank when both the lift and tilt control valves 12, 14 are in the hold or neutral position. Conduits 136, 138 allow the parallel coupling of the valves 12, 14, when either or both valves are shifted to an operative or open position. Therefore, when fluid flow is restricted in conduit 136, when tilt cylinder 46 bottoms out, fluid flow is diverted to lift cylinder 64 by conduit 138. Valves 12, 14 are released from the detent position when the magnet 114 triggers on the normally-closed switch 106. The bucket is thus in position to be dumped, whereupon the operator is ready to begin the next work cycle.
Although the embodiment of FIGS. 2 4 is herein described using two parallel electrical circuits, one for the bucket lift process and one for the bucket tilt process, it is to be understood that either of the electrical circuits may be used alone, as described with reference to the FIG. 1 embodiment. Likewise, the solid state relay circuit of FIGS. 2 4 may be employed in the embodiment of FIG. 1.
electromagnet means disposed to hold the control valve means in a given operating position when energized via selected movement of the control valve means;
' normally-open magnetically-responsive switch means associated with the control valve means;
first magnetic field means including a first permanent magnet and lever means directly and positively coupled to the control valve means for selected movement therewith to a position adjacent the normally-open switch means to close the latter in response to the selected movement of the control valve means;
normally-closed magnetically-responsive means associated with the hydraulic cylinder means and disposed in series with the normallyswitch I open switch means, the electromagnet means and I the electrical energy source; second magnetic field means including a second permanent magnet coupled to the cylinder rod for selected movement therewith to a position adjacent the normally-closed switch means to open the latter in response to selected translation of the cylinder rod of the hydraulic cylinder means; said normally-open and normally-closed switch meansv being disposed to respectively energize and de-energize the electromagnet means in response to the selected movements. 2. The electromagnetic positioner of claim 1 further including a second pair of normally-open and normallyclosed switch means disposed in parallel with the first normally-open and normally-closed switch means, and a second pair of first and second magnetic field means disposed to selectively close and open the second pair of normally open and closed switch means respectively, wherein closure of either of the normally-open switch means energizes the electromagnet means and opening both of the normally-closed switch means de-energizes the electromagnet means.
3. The electromagnetic positioner of claim 2 wherein the vehicle includes a pair of hydraulic cylinder means having respective cylinder rods selectively coupled to the given vehicle component for cooperative lift and tilt operations, the combination further including a pair of self-centering control valve means, said electromagnet means being disposed to hold the control valve means in given operating positions upon selected movement of the latter in response to closure of at least one of the normally-open switch means.
4. The electromagnetic positioner of claim 3 further including, a single control lever disposed for fore-andaft and side-to-side movement, and mechanical linkage means coupling the single control lever to the pair of self-centering control valve means to allow respective translation of the pair of valve means in response to selected fore-and-aft and side-to-side movement of the single control lever.
5. The electromagnetic positioner of claim 3 wherein the electromagnet means includes a single electromag net disposed to hold both the control valve means in their operating positions, the positioner further including a parallel hydraulic fluid flow system coupled between the source of hydraulic fluid and the pair of hydraulic cylinder means to channel all the flow of hydraulic fluid to one cylinder means when the cylinder rod of the other has translated to either limit, notwithstanding the position of the control valve means associated with the latter.
6. The electromagnetic positioner of claim 1 further including solid state. relay means disposed to connect the electromagnet means and the electrical 'energy source in response to closure of the normally-open switch means, and to disconnect them in response to opening of the normally-closed switch means.
7. The electromagnetic positioner of claim 6 wherein the solid state relay means includes a first transistor coupled to the normally-open and normally-closed switch means and responsive thereto, and a second transistor coupled to the-first transistor and responsive thereto to provide completion of the electrical circuit between the electromagnet means and the electrical energy source, the relay means being activated upon closure of the normally-open switch means and deactivated upon opening the normally-closed switch means.
mally-closed switch means.