Patent Publication Number: US-6220567-B1

Title: Interlock mechanism for controlling attachment to a work vehicle

Description:
FIELD OF THE INVENTION 
     The present invention relates to control of fluid actuated and mechanically linked implements and attachments on work vehicles, such as backhoe, skid steers, front end loaders, hydraulic cranes, etc. In particular, the present invention relates to an interlock mechanism to prevent movement of the work vehicle attachments without selective control by an operator of the work vehicle. 
     BACKGROUND OF THE INVENTION 
     Currently used hydraulically activated work vehicles, such as backhoes, front end loaders, skid steers, hydraulic cranes, etc. use fluid control valves to direct the motion of various functions on these machines, such as swinging, booming, bucket dipping and bucket rotation. These control valves allow fine control of the various functions as the associated valve spool is moved to and from its neutral position. 
     The typical function of hydraulic equipment currently uses valve timing, which is either slightly metered in, neutral or slightly metered out. Typically, valve designers avoid the use of heavy metering in or heavy metering out functions as a result of energy considerations. More specifically, depending upon the amount of metering, energy can be wasted since high metering restrictions usually result in the operation of the hydraulic pump such that the associated driving engine has to generate additional power to force fluid through restrictions associated with heavy metering. However, there are certain functions on hydraulic equipment, such as a backhoe, which are usually operated at relatively high pressures (e.g., the swinging motion), or having an overrunning load (e.g., the hydraulics associated with a boom) which have a potential to generate pressure appropriate to generate a metering out conditions. Most control valves have a spool which has metering notches which meter the flow when there is partial movement of the spool. Maintaining the control valve spool in a neutral position to prevent unwanted movement of a backhoe function resulting from fluid flow and pressure build-up through the spool metering notches is an important and desirable characteristic. 
     Existing devices for control valve locks include mounting a solenoid directly to the valve body to allow the solenoid rod to engage a recess in the valve spool. Locking of control valve spools using solenoids, in the part, required extensive use of levers as shown in U.S. Pat. No. 4,011,959. An alternative means for locking a valve spool in a desired location is use of a pin engaging a recessed area in the valve spool as disclosed in U.S. Pat. No. 4,793,378. Such arrangements require redesign of existing valve bodies to accommodate such locking devices which is expensive and in some cases not possible because of alignment difficulties. Retro-fitting control valves on equipment already in the market cannot be easily or inexpensively accomplished if the solenoid must be mounted on the control body. 
     Thus, there is a need for an interlock mechanism that will maintain a control valve spool in a neutral position to prevent fluid flow pressure from operating any of the work vehicle functions without selective control by an operator of the work vehicle. There is also a need for an interlock mechanism that can lock the control valve spool in a neutral position without mounting the actuator directly on the valve body. There is a further need for the ability to retro fit existing control valves with a valve lock without a complete redesign or extensive modifications to the valve body. 
     SUMMARY OF THE INVENTION 
     There is provided in accord with the present invention a work vehicle having a fluid actuated and mechanically linked attachment, which attachment is operatively connected to a valve having a control valve spool reciprocally mounted in the control valve body and having a control valve lock mounted thereon. The work vehicle may have four wheels, with 2 or 4 wheel drive and can also be an articulated vehicle or a tracked vehicle. The control valve lock comprises a rod engaged at one end with the valve spool and having a groove at the other end, with the rod maintaining a centering spring assembly in contact with the valve spool. An actuator, such as a solenoid, is mounted and orientated normal to the rod. The actuator or a solenoid has a pin aligned to selectively engage the groove in the rod. The solenoid is in operative communication with a control switch to selectively operate the solenoid. 
     The control valve lock can be mounted on the control valve body in several ways. In one embodiment a solenoid is mounted in a solenoid block which is mounted on the valve body. In another embodiment, a solenoid is mounted on an outer cap, which fits over an inner cap. The inner cap is mounted on the valve body. A retainer ring engages a corresponding groove in each of the outer cap and the inner cap to secure the outer cap to the inner cap. An additional embodiment mounts a solenoid to a lock block that is removably mounted to a mounting plate. The mounting plate is supported between the valve body and the lock block by an inner cap that threadingly engages the valve body. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an illustration depicting the interlock mechanism of the present invention mounted on a control valve used to control the swing function of a backhoe mounted on a work vehicle. 
     FIG. 2 is an exploded, perspective view of one embodiment of the interlock mechanism of the present invention, which interlock mechanism is attached by bolts to the valve body of the control valve. 
     FIG. 3 is a side sectional view of the assembled and mounted interlock mechanism shown in FIG.  2 . 
     FIG. 4 is an exploded, perspective view of one embodiment of the interlock mechanism of the present invention, which interlock mechanism is attached by threadingly attaching an inner cap to the valve body and using a retainer ring to attach an outer cap that supports a solenoid. 
     FIG. 5 is a side sectional view of the assembled and mounted interlock mechanism shown in FIG.  4  and illustrating the retainer ring in an uncompressed state. 
     FIG. 5 a  is a detail side sectional view illustrating the retainer ring in a compressed state. 
     FIG. 6 is an exploded, perspective view of one embodiment of the interlock mechanism of the present invention, which interlock mechanism is attached by threadingly attaching an inner cap to the valve body, which supports a mounting plate used to mount a lock block that supports a solenoid. 
     FIG. 7 is a side sectional view of the assembled and mounted interlock mechanism shown in FIG.  6 . 
    
    
     Before explaining the preferred embodiment of the invention in detail, it is to be understood that the invention is not limited in the application to the details of construction and the arrangement of components set forth in the following description or as illustrated in the drawings. The invention is capable of other embodiments or being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, FIG. 1 illustrates a work vehicle  1  having a vehicle support structure  90  to which a plurality of wheels  92  are rotatably attached. An engine  95  is mounted on the vehicle support structure  90  and is coupled to a transmission  94 . The transmission  94  is coupled to two or more wheels  92  with a mounted backhoe attachment  2 , such as an arm  97 . The work vehicle shown is of the tractor type having four wheels with 2 or 4 wheel drive. However, the vehicle could also be an articulated vehicle or a tracked vehicle wherein wheels support the tracks. Various attachment functions of the work vehicle  1  are controlled by a control valve  3  that through a combination of fluid actuated connections and mechanical linkage, such as a hydraulic pump  96  and hydraulic actuator  98 , manipulate the attachments. The backhoe attachment  2  extends and retracts the boom, dips and rotates the bucket and swings, left and right, during its various operations. Control of each movement is accomplished by manipulating a control valve  3 . A control valve body  4  is mounted on the work vehicle  1  and typically each function is controlled by a separate control valve. FIGS. 2,  4  and  6  illustrate three separate embodiments to the present invention in an exploded perspective view. FIGS. 3,  5  and  7  illustrate a sectional side view of the respective embodiments in an assembled and mounted (to a control valve  3 ) on a valve body  4 . 
     Referring to FIGS. 2 and 3, there is illustrated one embodiment of the present invention. The control valve spool  5  is reciprocally mounted in the control valve body  4 . The control valve spool  5  typically moves in relation to fluid entering or leaving the various ports in the valve body  4  in response to action of the operator of the work vehicle  1 . At certain times it is desirous to have the valve spool  5  in a neutral position. That is, the function of the attachment should not be operative and more importantly cannot be inadvertently activated by the operator of the work vehicle  1  or some other person. The present invention is a control valve lock  10  that will maintain the valve spool  5  in a selected position, neutral for instance, until the operator of the work vehicle  1  enacts a certain logic, such as sitting in the operator&#39;s seat. 
     The valve spool  5  is maintained in a position w;with a centering spring assembly  6  including a first spring cap  7 , a spring  8  and a second spring cap  9 . The two caps,  7  and  9 , and spring  8  are coaxial and are formed to receive a detent rod  12  along their common axes. The rod  12  has a threaded portion  14  on one end and a spring retainer shoulder  16  that butts against centering spring assembly  6  as the rod  12  is threaded into and engages the valve spool  5 . With the rod  12  threaded into the valve spool  5 , the centering spring assembly  6  is in contact with the valve spool  5  on one end and the spring retainer shoulder  16  on the detent rod  12  on the other end. The rod  12  has a groove  18  near the end of the rod  12  opposite the threaded portion  14  of the rod  12 . 
     A solenoid block  20  having a central bore  22  is formed to engage the valve body  4  and is coaxial with the valve spool  5 . The central bore  22  is at least large enough to accommodate the rod  12  and centering spring assembly  6 . The solenoid block  20  also is provided with a solenoid bore  24  orientated normal to and in communication with the central bore  22 . A solenoid block  20  is removably mounted to the valve body  4  and aligned with the rod  12  in the central bore  22  using mounting bolts  34 . The solenoid block can be made from any suitable material but should be compatible with the fluid used in the control valve  3 , such as hydraulic fluid. The solenoid block can be fabricated in any conventional manner, such as casting or machining or some combination thereof. A fluid seal  28  between the solenoid block  20  and the valve body  4  maintains fluid integrity between the two pieces The fluid seal can be a gasket between the two facing surfaces of the valve body  4  and the solenoid block  20  or can be an O-ring mounted in a groove on the portion of the solenoid block  20  that engages the valve body  4 . 
     A solenoid  30  having a pin is mounted in the solenoid bore  24  with the pin aligned to selectively engage the groove  18  of rod  12 . When the solenoid  30  is energized by a suitable power source, the pin is moved towards the electrical coil in the solenoid  30  and out of the groove  18  in the rod  12 . When the solenoid  30  is de-energized, a spring or other suitable biasing device associated with the solenoid extends the pin into the groove  18  of the rod  12  thereby locking the valve spool  5  in a fixed position, typically the neutral position. A solenoid shield  32  may be mounted on the solenoid block  20  and partially covering the solenoid  30  as protection from external forces. The solenoid shield  32  can be mounted in any convenient manner; however, the preferred embodiment utilizes the mounting bolts  34  that attach the solenoid block  20  to the valve body  4 . A fluid seal can be provided between the facing surfaces of the solenoid shield  32  and the solenoid block  20 . The solenoid block  20  can also be provided with a check valve grommet  36  in fluid communication with the central bore  22  of the solenoid block  20  to allow fluid out of the central bore  22  when necessary. The preferred embodiment has the check valve  36  in coaxial alignment with the central bore  22 . A control switch  38  is in operative communication with the solenoid to selectively operate the solenoid by energizing or de-energizing the solenoid  30  as determined by the operator of the work vehicle  1 . The control switch  38  can be a manually operated switch, a seat switch or some other logical sequence that provides selective control by the operator of the work vehicle of the particular function to which the control valve lock  10  is associated. 
     Referring now to FIGS. 4 and 5 which illustrate another embodiment of the present invention, in this embodiment an inner cap  70  configured to threadingly engage the valve body  4  coaxially with the valve spool  5 , has a central bore  22  and is provided with an external retainer ring groove  74 . The threaded portion  72  of the inner cap  70  mates with corresponding threads in the valve body  4 . Most valve bodies have a threaded portion to allow access to the valve spools. A rod  12  engaged at one end with the valve spool  5  is provided with a groove  18  at its other end. The rod  12  maintains a centering spring assembly  6  in contact with the valve spool  5  and extends through the central bore  22  of the inner cap  70 . The centering spring assembly  6  is as previously described above and is maintained coaxially with the valve spool  5  by the spring retainer shoulder  16  on the rod  12 . An outer cap  80  configured to removably cover the inner cap  70  has an inner bore  84  at least large enough to accommodate the inner cap  70 . The outer cap  80  is provided with an interior retainer ring groove  82  corresponding to the external retainer ring groove  74  in the inner cap  70 . A retainer ring  78  fits in both grooves  74 ,  82  to attach the outer cap  80  to the inner cap  70 . The detail of such engagement is shown in FIG.  5 A. In operation, the retainer ring  78  is compressed and nests in the exterior retainer ring groove  74  of the inner cap  70  while the outer cap is placed over the inner cap thereby covering it. When the retainer ring  78  is relaxed, a portion of the retainer ring  78  engages the interior ring groove  82  in the outer cap  80  so that a portion of the retainer ring  78  is in both such grooves  74 ,  82 . In such configuration, the outer cap is mounted over the inner cap. The outer cap is provided with a solenoid bore  24  oriented normal to and in communication with the inner bore  84  of the outer cap  80  and the central bore  22  of the inner cap  70 . A fluid seal  28  can be provided between the inner cap  70  and the outer cap  80  to maintain the fluid integrity of the valve body  4 . The preferred embodiment of the present invention uses an O-ring for the seal which is mounted in a seal groove  76  on the exterior of the inner cap  70 . A solenoid  30  having a pin is mounted in the solenoid bore  24  of the outer cap  80  with the pin aligned to selectively engage the groove  18  of the rod  12 . The operation of this embodiment of the control valve lock  10  of the present invention is as described above. The outer cap  80  may also be provided with a one-way check valve  36  mounted coaxially and in communication with the inner bore  84  of the outer cap  80  to allow fluid out of the inner bore  84 . A control switch  38  which is in operative communication with the solenoid  30  to selectively operate the solenoid may also be provided and operate as previously described. 
     Referring now to FIGS. 6 and 7 which illustrate another embodiment of the present invention, in this embodiment an inner cap  48  configured to threadingly engage the valve body  4  coaxially with the valve spool  5  is provided with a central bore  22  and a mounting plate shoulder  52 . The threaded portion  50  of the inner cap  48  engages the valve body. A mounting plate  40  having a through bore  22  at least large enough to receive the inner cap  48  up to the mounting plate shoulder  52  is positioned between the valve body  4  and the inner cap  48 . As the inner cap  48  is threaded into valve body  4 , the mounting plate  40  is supported by the inner cap  48 . The mounting plate  40  is provided with at least one threaded hole for securing a lock block  56 . Threaded fasteners engaging the mounting plate  40  through the holes in the lock block  56  cause the mounting plate  40  and the lock block  56  to clamp around the inner cap  48  thereby securing them in place. A rod  12  engaged at one end with the valve spool  5  is provided with a groove  18  at its other end. The rod  12  maintains a centering spring assembly  6  in contact with the valve spool  5  and extends through the central bore  22  of the inner cap  48 . A lock block  56  having a cavity  58  at least large enough to receive the inner cap  48  and the coaxially detent rod  12  is attached to the mounting plate  40  with at least one fastener  34  engaging the threaded hole  46  of the mounting plate  40 . The lock block  56  is also provided with a solenoid bore  24  oriented normal to and in communication with the interior cavity  48 . A solenoid  30  having a pin mounted in the solenoid bore  24  with the pin aligned to selectively engage the groove  18  in the rod  12 . The present invention may also be provided with a fluid seal  28  mounted in a seal groove  76  on the inner cap  48  between the inner cap  48  and the lock block  56 . The lock block  56  may also be provided with a one-way check valve  36  in communication with and coaxial with the interior cavity  58  to only allow fluid out of the cavity  58 . A control switch  38  in operative communication with the solenoid  30  to selectively operate the solenoid may also be provided and operated as previously described. The fabricating of the lock block  56  can be in any conventional method, such as casting, machining or a combination thereof, and can be manufactured in any convenient material provided such material is compatible with the fluid used in the control valve  3 , such as hydraulic fluid. 
     Thus, it should be apparent that it has been provided in accordance with the present invention of a work vehicle having a fluid actuated and mechanically linked attachment, which attachment is operatively connected to a valve having a control valve spool reciprocally mounted in the control valve body and having a control valve lock mounted thereon, which control valve lock mounted thereon which control valve lock is selectively controlled by the operator of the work vehicle has been disclosed. Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those ordinarily skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and scope of the appended claims.