US3717073A

US3717073A - Proximity switch magnet control for bucket positioner

Info

Publication number: US3717073A
Application number: US00156095A
Authority: US
Inventors: J Fuzzell
Original assignee: Caterpillar Tractor Co
Current assignee: Caterpillar Inc
Priority date: 1971-06-23
Filing date: 1971-06-23
Publication date: 1973-02-20
Anticipated expiration: 1990-02-20

Abstract

A bucket position limiting switch controlled by a magnet fastened between a pair of springs, one of which is fastened to the cylinder and the other of which is fastened to the piston rod of a loader bucket dump control cylinder. The control of the switches relative to the full travel of the cylinder rod in the small space of the switch mounting area is accomplished by mounting the magnet with a predetermined number of active coils in each of the springs so that the magnet moves only a predetermined proportion of the distance the cylinder rod travels.

Description

United States Patent [1 1 Fnzzell [4 1 Feb. 20, 1973 s41 PROXIMITY SWITCH MAGNET 3,143,042 8/1964 CONTROL FOR BUCKET POSITIONER 3,1 ,185 6/1 5 [1 lnv 49 E; F z lljIPi Mi ii i: 1323'??? 311323 [73] Assignee: Caterpillar Tractor Co., Peoria, lll. [22] Filed: June 23, 1971 Primary Examiner-Paul E. Maslousky [211 App! No: 156,095 Attorney-Fryer, Tjensvold, Feix, Phillips & Lempio Related U.S. Application Data [57] ABSTRACT [63] Continuation of Ser. No. 832,775, June 12, 1969, A bucket position limiting switch controlled by a magabandoned. net fastened between a pair of springs, one of which is fastened to the cylinder and the other of which is U.S. Cl 91/459 fastened to the piston rod of a loader bucket dump [51] f: C P 944 control cylinder. The control of the switches relative [58] Flew of Search '1 "927131; 9156751 338 to the full travel of the cylinder rod in the small space 91/ 358 R, 388, 27 S, 3 3 A of the switch mounting area is accomplished by mounting the magnet with a predetermined number of active coils in each of the springs so that the magnet [56] References cued moves only a predetermined proportion of the UNITED STATES PATENTS distance the cylinder rod travels.

2,755,966 7/1956 Lindars ..9ll275 8 Claims, 5 Drawing Figures V O A PATENTEDFEB201973 3 3,717,073

SHEET 1!)? 4 RESERVOIR H m E- MENTOR JOE E. FUZZELL PATENTEIJ FEB2O 1975 3,717, 07 3 SHEET 2 BF 4 INVENTOR JOE E. FUZZELL M/ W wfw w PATENTED FEB 2 0 I973 SHEET 3 a? 4 .PATENTED FEBZO I073 SHEET L CF INVENTOR JOE E. FUZZELL ATTORNEYS PROXIMITY SWITCH MAGNET CONTROL FOR BUCKET POSITIONER This application is a continuation of application, Ser. No. 832,775, now abandoned, filed June 12, 1969.

BACKGROUND AND SUMMARY OF THE INVENTION The present invention relates generally to a loader bucket positioning device and more particularly to an assembly for actuating one or more electrical switches which control a hydraulic circuit so as to limit the tilting of a loader bucket. Although the assembly is described herein with reference to a loader bucket, it will be obvious to those skilled in the art that it is readily adaptable to many other applications.

One example of the type of proximity switch which may be utilized with this invention has been shown in U.S. application, Ser. No. 812,829, filed Apr. 2, 1969 and assigned to the assignee hereof. An example of a hydraulic circuit which may be controlled by such a switch is shown in U.S. Pat. application, Ser. No. 770,670, filed Oct. 25, 1968 and also assigned to the assignee hereof.

Bucket loaders generally have a bucket pivotally supported by lift arms with tilt jacks interconnected within the lift arms and the bucket by suitable tilt linkage. The tilt linkage generally maintains the bucket in a constant tilt position while it is being raised or lowered upon the lift arms. Additionally, the tilt linkage permits the bucket to be pivoted forwardly or rearwardly, for example between its carry and dump position, in response to operation of the tilt jacks.

It has been found desirable to provide a means for automatically positioning the bucket to perform certain functions. Automatic positioning means are most commonly employed for establishing the bucket in a load position where its floor is generally parallel to the ground. The pivoted position of the bucket is somewhat critical in this position and the operators view of the bucket is generally obstructed as the bucket is approaching ground level.

The load position of the bucket can be best determined by the relative extension of the hydraulic tilt jacks. In the prior art, hydraulic control valves have been commonly employed for establishing this position of the bucket. However, the valve components are generally exposed to dirt and other debris during loading so that they are subject to fouling or mechanical damage. Such failure commonly prevents effective operation of the bucket positioning arrangement and sometimes interferes with operation of the entire tilt control system.

In the above cited U.S. application, Ser. No. 770,670, a system was disclosed which provides an electrical bucket positioning arrangement which is positively responsive to the position of the bucket. While the design taught in that application produces good results, its application to large machines has proven to be only partly satisfactory since the length of the bracket necessary for holding the switch in proper position is such that it interferes with the bucket when the bucket is racked back to the carry position.

In the present invention, a system is provided wherein the proximity switch is protected from damage by moving it to a position at the upper end of the tilting jack. Further, a control magnet which actuates the switch is mounted between two springs so that as the piston rod extends from the cylinder the springs are stretched and the control magnet is propelled past the proximity switch. Since the control magnet is attached between two springs, one of which is attached to the cylinder and the other of which is attached to the piston rod, the distance it travels in relation to the distance the rod moves is dependent upon the number of active coils in each of the two springs. Thus, by controlling the number of active coils on each side of the control magnet, the movement of the magnet can be set to be a predetermined proportion of the movement of the piston rod. This allows for control of the proximity switch relative to the full travelof the piston rod in a small longitudinal dimension, relative to the length of the cylinder.

As another feature or object of this invention, the proximity switch, such as that taught in the above cited U.S. Pat. application, Ser. No. 812,829, may be located off center relative to the control housing so that rotation of the switch will alter the position at which the control magnet will cause the switch to open or close.

Further, if desired a second proximity switch may be actuated by the control magnet so as to limit the dumping of the bucket, thereby diminishing structural stresses in the arms.

This invention, together with its further objects, advantages, modes, and embodiments, will become obvious to those skilled in the art by reference to the Detailed Description and accompanying drawings which illustrate what is presently considered to be the preferred embodiments of the best mode contemplating for utilizing the novel principles set forth in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 illustrates the forward portion of a bucket loader and a partially schematic representation'of a control circuit for the loader bucket as an exemplary environment for the present invention;

FIG. 2 is a side elevation, partly in section, of the upper end of the tilt jack cylinder and the extension thereof;

FIG. 3 is a side elevation, in section, of the axial tube within the extension of the tilt jack cylinder;

FIG. 4 is a cross-sectional view of the extension of the tilt jack cylinder, taken along a line IV-IV of FIG. 2; and

FIG. 5 is a view, similar to FIG. 2, showing an alternate embodiment of the means for mounting the control system on the tilt jack cylinder.

DETAILED DESCRIPTION Referring now to FIG. 1, a vehicle 11 has a loader bucket 12 pivotally supported as at 13 upon a pair of lift arms, one of which is shown at 14. A tilt motor or hydraulic jack having a cylinder 16 and an extensible piston rod 17 is interconnected between each of the lift arms 14 and the bucket 12 by means of a tilt linkage which includes a lever 19 and a link 21 connecting the lever with the bucket 12. Raising and lowering of the bucket is accomplished by lift jacks 15 which are interconnected between the vehicle and the lift arm 14.

A control circuit for operating the bucket, and particularly for operating the tilt jack 16, is illustrated by the schematic portion of the drawing generally designated at 26. A tilt control valve 27 includes a spool 28 which is positioned by an operator actuated lever 29 to selectively communicate hydraulic fluid under pressure from a pump 31 and inlet conduit 32 into the head end and rod ends of the cylinder 16 via

conduits

33 and 34, respectively.

The bucket 12 may be racked back, or pivoted in a counter-clockwise direction as viewed in FIG. 1, by shifting the lever 29 and spool 28 toward theleft. With the spool thus shifted, fluid from the conduit 32 is directed to the rod end of cylinder 16 through the conduit 34 so that the rod 17 tends to be retracted within the cylinder 16. The bucket may also be dumped, or pivoted in a clockwise direction as viewed in FIG. 1, by shifting the lever 29 and spool 28 to the right. This causes fluid to be directed through the conduit 33 to the head end of the cylinder 16 so that the rod 17 is extended and the bucket is moved in the clockwise direction. As shown in FIG. 1, the lever and spool are in such a position as to isolate the cylinder 16 from the fluid circuit so that the tilt jack 16 is prevented from moving the bucket.

Within such a control circuit, it is desirable that the operator be able to position the lever 29 for selected pivotal movement of the bucket and then direct his attention to operation of the vehicle while tilting movement of the bucket is automatically terminated during selected portions of a loading cycle.

To commence a typical loading cycle, the bucket is placed in a position as illustrated in FIG. 1. The vehicle is then driven forwardly to load material into the bucket. As is common in such operations, the bucket is then alternately raised by lift jack and racked back by tilt jack 16 in order to accomplish more complete loading of the bucket. This operation is commonly referred to as fishtailing of the bucket. When complete loading of the bucket is accomplished, it is then completely racked back to a carry position (not shown) and raised by the lift jacks 15 to a position suitable for dumping. With the bucket then positioned over a transport vehicle or dump site, it is pivoted forwardly, in a clockwise fashion beyond the position shown in FIG. 1, to unload material from the bucket.

While the above cycle is completed, the operator may be fully occupied with steering the vehicle and returningit to the loading site to commence a new loading cycle. Accordingly, it is desirable that he be able to position the lever 29 and have the bucket automatically return to its loading position.

To permit automatic operation of the tilt controls, a detent mechanism 36 is associated with the lever 29. The detent mechanism includes a roller 37 mounted on a pivotal lever 38. The lever is urged leftwardly, as seen in FIG. 1, by a spring 39 so that as the lever 29 is pivoted, the roller 37 becomes engaged in one of the detent notches 41 on the lever 29. As the bucket reaches its fully racked back or dump position, depending upon the direction of movement of lever 29, a slave cylinder 42 is actuated, by a means to be described hereafter, to pivot lever 38 rightwardly, thereby allowing lever 29 to pivot to the position in FIG. 1 under the influence of a spring 40 within the valve 27. This stops the flow of fluid to cylinder 16.

Lever 38 is pivoted rightwardly by the introduction of fluid into the valve 42, from a conduit 44, to act against a spool 43 in the valve which is connected to the lever. Communication of fluid through the conduit 44 is regulated by a solenoid operated, spring loaded valve 46 which is normally positioned by its spring to prevent communication of fluid to the slave cylinder 42. When such communication is prevented, the detent roller 37 is free to engage lever 29 under the influence of the spring 39. However, upon actuation of the solenoid valve 46, fluid is directed through the conduit 44 to the slave cylinder 42 so that the lever is pivoted in the manner described.

Referring now to FIG. 2, the cylinder 16 comprises a forward section 51, a spacer section 53, and an extension section 55. As shown, fluid in line 33 enters the extension section 55 via a port 57. The fluid passes through a compartment 59 in the extension 55' and then through a port 61 in spacer section 53 and into the cylinder forward section 51 wherein it acts against the head end of a piston 63'mounted on the rod 17. The fluid entering the cylinder from line 33 causes the piston and rod to move toward the right as shown in the drawing, thereby extending the rod from the cylinder. Retraction of the rod is accomplished by applying fluid pressure to the rod side of the piston 14 through a line 34 (FIG. 1).

The bucket positioner arrangement comprises a pair of proximity switches 65 and 67 mounted within the outer wall of the extension member 55, and a tube assembly 69 which contains a control magnet 71 therein (FIG. 3).

In general, tube assembly 69 comprises a non-magnetic tube 73 having one end secured within a bushing 75 and the opposite end closed by a plug 77. The control magnet 71 is integrally encased within a housing 79 which is secured to springs 81 and 83. The opposite end of spring 81 is secured to the plug 77 and the opposite end of the spring 83 is secured to an adapter 85 which is attached to the rod 17 by a screw portion 87.

In this particular illustration, spring 83 contains twice as many active coils as does spring 81. Since the bushing 75 is contained within the spacer section 53 by means of a set screw 89, the tube will be held stationary within the extension member and spacer section and, since spring 83 is fixed to the piston rod 17, movement of the rod to the right will cause the magnet 71 to also be moved to the right. Further, due to the active coil ratio between springs 81 and 83, the control magnet will move to the right one-third the distance which the rod moves. Obviously, variation of the active coil ratio will also vary the distance of the control magnet will move. A set of slots or openings may be formed in each end of the tube 73 so as to equalize the pressure on both sides of the control magnet housing 79.

In FIG. 4, a sectional view of the proximity switch 65 has been illustrated, the proximity switch 65 being identical in structure to switch 67. As the control magnet 71 moves to the right in FIG. 3, switch 65 will open. When the magnet moves to the left, the switch will close. Basically the switch assembly consists of a reed switch 91 and a biasing magnet 93 disposed off-center within a cylindrical housing 95. The housing has a reduced portion 97 machined thereon and disposed within a plug 99 secured within a member 101 which is secured or fitted into the extension member 55. A nut 103 holds the housing 95 in the predetermined position. Since the reed switch 56 is located off-center in the housing 95, the point at which the switchopens or closes can be adjusted by loosening the nut 103 and rotating the housing. A more detailed discussion'and illustration of a switch which may be used as the proximity switch in this case will be found in U.S. Pat. application, Ser. No. 812,829 filed Apr. 2, 1969.

To limit the bucket dumping, the switch 67 closes as the piston is extended from the cylinder when the control magnet reaches the position indicating that the bucket has been fully dumped, thereby stopping the dumping action. Upon movement of the control magnet to the left, the switch 67 is once again opened. The switch 67 is used for a stop dump control to return the control valve 26 to the neutral position when the bucket reaches the dump position.

Switches

65 and 67 are each connected in series with the solenoid 105 of the solenoid valve 46. When the solenoid 105 is actuated, it causes the solenoid valve to move to the position shown in FIG. 1 so as to pressurize the slave cylinder 42, thereby serving to withdraw the roller 37 from either of the detents 41, allowing the control valve 26 to return to a neutral position.

The

switches

65 and 67 are also in series with a battery 107, a normally opened pressure switch 109, and a master switch 111 which controls the complete electrical circuit for the loader 11. The switch 109 remains closed during operation of the vehicle, but automatically functions to break the circuit with the solenoid 105 in the event the machine is shut down while switch 1 1 1 is in a closed position.

In operation, when the vehicle operator moves lever 29 toward the left, or rack back position, the roller 37 will be engaged within the lower detent 41, thereby serving to hold the lever in the position so that the operator may devote his attention to driving the vehicle. In this condition, fluid will enter the rod end of the cylinder 51 via the line 34, thereby serving to withdraw the piston rod 17 into the cylinder. This causes the control magnet 71 to move to the left and, as it passes proximity' switch 65, that switch will close actuating solenoid 105 so as to motivate the solenoid valve 46 to the position shown. As previously explained, this causes lever 38 to move to the right, allowing lever 29 to pivot to the neutral position due to the force of spring 40.

When the operator moves the lever toward the right, or dump position, fluid will enter the head end of the cylinder via line 33. As the piston rod 17 is extended from the cylinder, the control magnet 71 will move to the right. As it passes proximity switch 65 that switch will open, but as it passes proximity switch 67 that switch will close. The closing of switch 67- will actuate the solenoid valve 46 in the manner previously described. Thus, the vehicle operator can actuate the loader bucket to the rack back or dump position and then turn his attention to other tasks, confident that the bucket will stop at its extreme racked back or dumped position and the control valve will return to neutral.

Referring now to the alternate embodiment of the invention shown in FIG. 5, those portions of the structure which are nearly identical and clearly equivalent to the portions illustrated in the preferredembodiment have been similarly labeled, but within the "100 series. Thus, piston rod 17 becomes piston rod 117 in the alternate embodiment, cylinder 51 becomes cylinder 151, and so forth. Therefore, a reference to the previously described embodiment should suffice to provide a clearer understanding of the relationship and structure of the parts thus similarly labeled.

In this embodiment, a non-magnetic casing 201 has been mounted on the outside of the cylinder 151. The end of spring 181 not attached to the control magnet housing 179 has been fixed to a bracket 203 at the upper end of the cylinder 151. The end of spring 183 which is not fixed to the control magnet housing 179 is fastened to a bracket 205 through the threaded section 187. Bracket 205 has been fixed to the piston rod 117 so that as the rod is extended from the cylinder 151, bracket 205 will serve, via the springs, to draw the control magnet toward the right. It will thus pass proximity switches and 167 which are mounted within a housing 207 mounted on the cylinder 151 so as to partially surround the housing 201.

The use of this alternate embodiment will produce an identical result to that produced by the originally described embodiment, but will allow the system to be used when space is not sufficient for a spacer and extension member to be added to the head end of the cylinder. Thus, this design is more compact in the longitudinal direction while still producing the result desired.

Thus the applicant has provided a plurality of embodiments of a new and improved concept in the art of loader bucket control, yielding a true advance in the art. Many further modifications and alterations will be obvious to those skilled in the art, wherefore what is claimed as the invention is:

I claim:

1. In combination with a reciprocating device having drive means moving a first member rectilinear relative to a second member, a ratio electrical switch system comprising:

at least one electrical switch means fixedly mounted in an adjacent relationship to said second member, said switch means having control contacts for making and breaking electrical circuits,

circuit means connected to said control contacts of said electrical switch means and to said drive means operable to control a movement of said members relative to one another;

an elastic means connected to said first and second members; and

a floating actuating means suspended by said elastic means between its connections to said first and second members and in a proximate relationship to said electrical switch means operable to actuate said control contacts by changing its relative position with respect to said contacts as said elastic means stretches and constricts because of relative movement of said members whereby a ratio of said movement is induced to said actuating means for switching which is proportional to the movement of said first and second members as it moves relative to said electrical switch means.

2. The combination as defined in claim 1 including an adjusting means between the connection of one end of said elastic means and its attachment to one of the members whereby the relative position of its floating actuating means in relationship to the first and second members so the operable position of the electrical switch means can be varied.

3. The combination defined in claim 1 wherein the elastic means is formed by two separate springs, one of said springs connected between one end of the actuating means and the first member and the other said spring connected between the opposite end of said actuating means and said second member.

4. The combination as defined in claim 1 wherein said control contacts are part of a magnetically-biased reed switch and the actuating means includes a magnet capable of operating said control contacts when in proximity thereto.

5. The combination as defined in claim 4 wherein said first and second members of the reciprocating device are respectively the rod and cylinder of a hydraulic motor and the drive means includes a fluid pressure source and control valve means for operating said hydraulic motor.

6. The combination as defined in claim 5 wherein the circuit means includes an electrically operated means responsive to the position of the control contacts operable to reposition the control valve means.

7. The combination as defined in claim 6 wherein the control valve means includes biasing means urging it in a direction to deactivate the hydraulic motor and the electrical operated means includes mechanical detent means for holding said control valve means in at least one on position and release means connected to said electrical valve means and operable to free said control valve means of said detent means when activated.

8. The combination as defined in claim 7 wherein the hydraulic motor forms part of a tilt linkage of a bucket loader and the control valve means includes a manual lever for moving it to the one on position.

at i t i

Claims

1. In combination with a reciprocating device having drive means moving a first member rectilinear relative to a second member, a ratio electrical switch system comprising: at least one electrical switch means fixedly mounted in an adjacent relationship to said second member, said switch means having control contacts for making and brEaking electrical circuits, circuit means connected to said control contacts of said electrical switch means and to said drive means operable to control a movement of said members relative to one another; an elastic means connected to said first and second members; and a floating actuating means suspended by said elastic means between its connections to said first and second members and in a proximate relationship to said electrical switch means operable to actuate said control contacts by changing its relative position with respect to said contacts as said elastic means stretches and constricts because of relative movement of said members whereby a ratio of said movement is induced to said actuating means for switching which is proportional to the movement of said first and second members as it moves relative to said electrical switch means.