Patent Publication Number: US-8523037-B2

Title: Control valve assembly for fastener-driving tool

Description:
CROSS REFERENCE TO RELATED PATENT APPLICATIONS 
     This patent application is related to, and based upon, U.S. Provisional Patent Application Ser. No. 60/809,930 which was filed on Jun. 1, 2006, the priority benefits of which are hereby claimed. This patent application is also related to, and based upon, PCT Patent Application PCT/US2007/010698 which was filed on May 1, 2007 and WO 2007/142766 which was published on Dec. 13, 2007, the priority benefits of which are also hereby claimed. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to fastener-driving tools, and more particularly to a new and improved trigger-actuated eccentric control valve assembly for use in a fastener-driving tool wherein a spring-biased, trigger-actuated control valve member is disposed internally within upper and lower valve spool or valve housing members of the trigger-actuated eccentric control valve assembly. The upper and lower valve spool or valve housing members are adapted to be fixedly mated together by means of a bayonet-type connection, defined by means of a pair of diametrically opposed dovetail lug members disposed upon the lower valve spool or valve housing member and a gripping ledge structure defined upon the upper valve spool or valve housing member, as a result of the upper and lower valve spool or valve housing members being angularly rotated a predetermined amount with respect to each other. In this manner, the trigger-actuated eccentric control valve assembly can be pre-assembled together prior to its disposition and assembly within the fastener-driving tool housing. In addition, the trigger-actuated eccentric control valve assembly of the present invention is fluidically connected to the upper control air chamber of the fastener-driving tool by means of externally disposed air passages which are cast within the fastener-driving tool housing in such a manner that the air passages need not be machined according to complex compound angle orientations or arrangements. 
     BACKGROUND OF THE INVENTION 
     Trigger-actuated control valve assemblies are conventionally utilized within fastener-driving tools so as to control the flow of air into and out from an upper air chamber which is disposed above the fastener-driving tool cylinder within which the fastener-driving piston, and the driver blade attached thereto, are movably disposed in order to drive and discharge fasteners through and out of the fastener-driving tool. During a typical fastener-driving tool firing cycle or operation, the upper air chamber is adapted to be charged with, and vented or exhausted of, air in accordance with the various stages of operation accompanying a fastener-driving cycle. An example of such a fastener-driving tool, within which such a trigger-actuated control valve assembly is disposed and utilized for controlling the flow of air into and out from the upper air chamber, is disclosed in U.S. Pat. No. 4,404,894 which issued to Oesterle on Sep. 20, 1983. In addition, as is also disclosed within  FIG. 1 , a conventional, PRIOR ART fastener-driving tool, generally indicated by the reference character  10 , has a trigger-actuated control valve assembly  12  disposed therein, and the trigger-actuated control valve assembly  12  has an air passage  14  fluidically connected thereto, and incorporated within the fastener-driving tool housing  13 , for controlling the air to be delivered to or charged into the upper air chamber, or for controlling the air to be vented or exhausted from the upper air chamber. More particularly, it is seen that the air passage  14  comprises a first, vertically oriented passageway or section  16  and, in order to achieve the fluidic communication between the first, vertically oriented passageway or section  16  and the trigger-actuated control valve assembly  12 , it is necessary, to incorporate a second, angularly oriented or inclined passageway or section  18  within the fastener-driving tool housing  13 . It is noted that a similarly structured air passage is disclosed within the aforenoted patent to Oesterle, however, in either case, it is extremely difficult to accurately machine such compound angle passages, particularly the angularly oriented or inclined passageways or sections thereof. Still further, such compound angle passages cannot be formed by means of a casting process in view of the fact that once the fastener-driving tool housing is fabricated from the cast material, which thereby forms the solid portions of the housing, around, in effect, mandrel members disposed within the mold structure for forming the aforenoted passages, there would be no way to extract or remove the mandrel members or structures from the cast housing structure. 
     Continuing further, it is additionally noted that, in connection with the fabrication of conventional, PRIOR ART trigger-actuated control valve assemblies, the trigger-actuated control valve assemblies usually comprise a multiplicity of component parts which therefore entails a substantially large inventory of component parts as well as a significant amount of time to assemble the component parts together. For example, the trigger-actuated control valve assembly comprises a housing which is usually fabricated as a two-part structure in order to be able to insert the actual trigger-actuated control valve mechanism internally therewithin, however, in accordance with a first type of trigger-actuated control valve assembly structure, separate fastener components, in the form of pins, rings, or the like, are required to fixedly secure the housing halves or complementary housing structures together. In accordance with a second type of trigger-actuated control valve assembly housing structure, the housing halves or complementary housing structures respectively comprise fastener components integrally formed thereon which have unique configurations, forms, contours, or the like that mandate or require the housing halves or complementary housing structures to be assembled together in a predetermined orientation or manner. Not only is the assembly or mating together of the housing halves or complementary housing structures therefore quite tedious, but in addition, the fabrication of such housing halves or complementary housing structures requires complex injection molding tooling. 
     A need therefore exists in the art for a new and improved trigger-actuated control valve assembly, for use within a fastener-driving tool, wherein the trigger-actuated control valve assembly can be fluidically connected to the upper control air chamber of the fastener-driving tool by means of externally disposed air passages which do not comprise compound angles and which can therefore be cast within the fastener-driving tool housing so as to effectively eliminate the need for machining such air passages in accordance with, or at, complex compound angle arrangements, wherein the trigger-actuated control valve assembly comprises two mating housing sections which can be readily assembled together in a relatively quick and easy manner without the need for separate fastener components to hold the assembled housing sections together, wherein the trigger-actuated control valve assembly comprises two mating housing sections which comprise interengaging fasteners which are integrally formed thereon and which are relatively easy to fabricate, and wherein the interengaging fasteners of the two mating housing sections of the trigger-actuated control valve assembly do not need to be necessarily oriented in a particular manner. 
     SUMMARY OF THE INVENTION 
     The foregoing and other objectives are achieved in accordance with the teachings and principles of the present invention through the provision of a new and improved trigger-actuated control valve assembly for use within a fastener-driving tool wherein a spring-biased, trigger-actuated control valve member is disposed internally within upper and lower valve spool or valve housing members of the trigger-actuated eccentric control valve assembly. The upper and lower valve spool or valve housing members are adapted to be fixedly mated together by means of a bayonet-type connection, defined by means of a pair of diametrically opposed dovetail lug members disposed upon the lower valve spool or valve housing member and a gripping ledge structure defined upon the upper valve spool or valve housing member, as a result of the upper and lower valve spool or valve housing members being angularly rotated a predetermined amount with respect to each other. In this manner, the trigger-actuated control valve assembly can be pre-assembled together in a relatively quick and easy manner prior to its disposition and assembly within the fastener-driving tool housing. In addition, the trigger-actuated control valve assembly of the present invention is fluidically connected to the upper control air chamber of the fastener-driving tool by means of externally disposed air passages which do not comprise complex compound angles or orientations with respect to each other and are therefore able to be cast within the fastener-driving tool housing. Still further, the casting of the air passages within the fastener-driving tool housing permits at least one of the externally disposed air passages to have a substantially large length dimension which would not otherwise be possible to accurately achieve by means of machining or drilling operations in view of the unsupported length of the machining or drilling tools. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various other features and attendant advantages of the present invention will be more fully appreciated from the following detailed description when considered in connection with the accompanying drawings in which like reference characters designate like or corresponding parts throughout the several views, and wherein: 
         FIG. 1  is a partial, cross-sectional view of a fastener-driving tool within which a conventional, PRIOR ART trigger-actuated control valve assembly is disposed, and wherein a substantially vertically oriented air passageway, having a compound angle configuration, is provided within the fastener-driving tool housing for fluidically connecting the trigger-actuated control valve assembly to the upper control air chamber of the fastener-driving tool; 
         FIG. 2  is a cross-sectional view of a new and improved fastener-driving tool housing section having cast therein the cavity within which the new and improved trigger-actuated control valve assembly of the present invention is to be disposed, as well as the air passageways fluidically connecting the new and improved trigger-actuating control valve assembly to the upper control air chamber of the fastener-driving tool; 
         FIG. 3  is a cross-sectional view of the new and improved fastener-driving tool housing section as disclosed within  FIG. 2  and as taken along the lines  3 - 3  of  FIG. 2 ; 
         FIG. 4  is an enlarged side elevational view of the new and improved trigger-actuated control valve assembly constructed in accordance with the principles and teachings of the present invention and showing the cooperative parts thereof; 
         FIG. 5  is a cross-sectional view similar to that of  FIG. 2  showing, however, the new and improved trigger-actuated control valve assembly of the present invention, as disclosed within  FIG. 4 , disposed within the valve assembly cavity cast within the new and improved fastener-driving tool housing section; 
         FIG. 6  is an enlarged cross-sectional view similar to that of  FIG. 5  showing, however, in greater detail, the disposition of the new and improved trigger-actuated control valve assembly of the present invention as disposed within the cavity cast within the new and improved fastener-driving tool housing section; 
         FIG. 7  is an enlarged vertical cross-sectional view of the new and improved trigger-actuated control valve assembly as disclosed within  FIG. 4 ; 
         FIG. 8  is an enlarged, top perspective view of the lower valve spool or valve housing member of the new and improved trigger-actuated control valve assembly, as disclosed within  FIG. 4 , illustrating the pair of diametrically opposed lug members which form part of the bayonet-type connection defined between the upper and lower valve spool or valve housing members of the new and improved trigger-actuated control valve assembly; 
         FIG. 9  is a partial, side elevational view of the lower valve spool or valve housing member, of the new and improved trigger-actuated control valve assembly, as disclosed within  FIG. 8 , showing the details of one of the diametrically opposed lug members which form part of the bayonet-type connection defined between the upper and lower valve spool or valve housing members of the new and improved trigger-actuated control valve assembly; 
         FIG. 10  is a bottom plan view of the upper valve spool or valve housing member of the new and improved trigger-actuated control valve assembly as constructed in accordance with the principles and teachings of the present invention; 
         FIG. 11  is an enlarged bottom perspective view of the upper valve spool or valve housing member of the new and improved trigger-actuated control valve assembly, as disclosed within  FIG. 10 , showing the details of the air flow windows formed within the upper valve spool or valve housing member as well as the ledge portion of the upper valve spool or valve housing member for cooperating with the diametrically opposed lug members forming the bayonet-type connection between the upper and lower valve spool or valve housing members of the trigger-actuated control valve assembly; and 
         FIG. 12  is a top plan view of the new and improved trigger-actuated control valve assembly as disclosed within  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, and more particularly to  FIGS. 2-7  thereof, a new and improved trigger-actuated control valve assembly, constructed in accordance with the principles and teachings of the present invention and adapted for use within a fastener-driving tool which is partially illustrated by means of its new and improved housing structure  100 , is disclosed and is generally indicated by the reference character  110 . More particularly, it is seen that the new and improved trigger-actuated control valve assembly  110  comprises an upper valve spool or upper valve housing member  112 , a lower valve spool or lower valve housing member  114 , and a trigger-actuated control valve member  116  movably disposed within the upper and lower valve housing members  112 , 114 . The upper valve housing member  112  is seen to have a stepped configuration comprising an upper substantially cylindrical portion  118  and a lower flanged portion  120 , while the lower valve housing member  114  is seen to comprise a substantially cylindrical member wherein the external periphery thereof is provided with an annular recess  122  at an axially central position thereof whereby the external periphery of the lower valve housing member  114  is effectively divided into an upper annular section  124  and a lower annular section  126 . A first lower annular O-ring sealing member  128  is disposed within the annular recess  122  of the lower valve housing member  114 , and a second upper annular O-ring sealing member  130  is disposed around the external periphery of the upper valve housing member  112  at the annular shouldered intersection or junction defined between the upper cylindrical portion  118  and the lower flanged portion  120  of the upper valve housing member  112 . 
     Continuing further, and as can best be appreciated from  FIG. 7 , it is seen that the trigger-actuated control valve member  116  comprises an upper head portion  132  having a stepped configuration, an intermediate body portion  134 , and a lower downwardly projecting valve stem portion  136  which extends downwardly through a bore  137  defined within the lower valve housing member  114 . In addition, a third annular O-ring sealing member  138  is disposed within an annular recessed portion defined between the intermediate body portion  134  and the lower downwardly projecting valve stem portion  136  of the trigger-actuated control valve member  116 , while a fourth annular O-ring sealing member  140  is likewise disposed within an annular recessed portion defined between the upper head portion  132  and the intermediate body portion  134  of the trigger-actuated control valve member  116 . Concomitantly therewith, a first, lower annular valve seat  142  is effectively defined upon an internal, substantially frusto-conically configured portion of the lower valve housing member  114 , while a second, upper annular valve seat  144  is effectively defined upon an internal portion of the upper valve housing member  112  at the intersection or junction of the upper cylindrical portion  118  of the upper valve housing member  112  and the lower flanged portion  120  of the upper valve housing member  112 . 
     In addition, it is seen that a first coil spring member  146  is disposed within an internal bore  147  defined within the upper cylindrical portion  118  of the upper valve housing member  112  such that the upper end portion of the first coil spring member  146  is engaged with and seated upon an internal end wall portion of an upper end cap portion  148  of the upper valve housing member  112 , while the lower end portion of the first coil spring member  146  is engaged with and seated upon the upper head portion  132  of the trigger-actuated control valve member  116 . In this manner, the trigger-actuated control valve member  116  will normally be biased downwardly by means of the first coil spring member  146  such that the third annular O-ring sealing member  138  will normally be seated upon the first annular lower valve seat  142 . Still further, a second coil spring member  150  is disposed beneath the lower valve housing member  114  such that an upper end portion of the second coil spring member  150  is engaged with and seated upon an underlying shouldered portion  152  defined upon an undersurface portion of the lower valve housing member  114  while a lower end portion of the second coil spring member  150  is adapted to be disposed in contact with an actuation lever, not shown, which is a component part of the fastener-driving tool trigger assembly. It is further seen that the upper end cap portion  148  of the upper valve housing member  112  has a through-bore  154  defined therein so as to be in fluidic communication with the bore  147  defined internally within the upper valve housing member  112 , while diametrically opposed side wall portions of the lower flanged portion  120  of the upper valve housing member  112  are respectively provided with a pair of windows  156 , 158 . 
     Accordingly, it can be appreciated that when the trigger member, not shown, of the fastener-driving tool trigger assembly is not actuated or depressed such that the actuation lever, also not shown, of the fastener-driving tool trigger assembly is not actuated or moved upwardly, the trigger-actuated control valve member  116  will be disposed at its normal, lowered position, as illustrated within  FIG. 7 , whereby the third annular O-ring sealing member  138  will be disposed upon its valve seat  142  while the fourth annular O-ring sealing member  140  will be unseated or removed from its valve seat  144 . Therefore, at this point in time, pressurized air from a suitable air source, not shown, will enter the throughbore  154  defined within the upper end cap portion  148  of the upper valve housing member  112 , will traverse internal bore  147  defined within the upper valve housing member  112 , and will be able to exit through the pair of diametrically opposed windows  156 , 158  so as to be conducted toward the upper control air chamber defined within the fastener-driving tool at a location above the fastener-driving tool actuating piston and driver blade assembly, not shown. 
     Alternatively, when the trigger member, not shown, of the fastener-driving tool trigger assembly is actuated or depressed such that the actuation lever, also not shown, of the fastener-driving tool trigger assembly is now actuated or moved upwardly so as to engage the lower end portion of the downwardly projecting valve stem portion  136  of the trigger-actuated control valve member  116 , the trigger-actuated control valve member  116  will be moved upwardly whereby the fourth annular O-ring sealing member  140  will now be engaged with and seated upon its valve seat  144  while the third annular O-ring sealing member  138  will now be disengaged or un-seated from its valve seat  142 . Accordingly, at this point in time, pressurized air from the air source, not shown, cannot pass by the fourth annular O-ring sealing member  140 , and concomitantly, the air present within the upper control air chamber of the fastener-driving tool at the location above the fastener-driving tool actuating piston and the driver blade assembly, not shown, will be able to be exhausted through the pair of diametrically opposed windows  156 , 158  and the throughbore  137  defined within the lower valve housing member  114 . It is to be additionally noted that a plurality of circumferentially or angularly spaced lug members  160 , such as, for example, three lug members  160 , although only one of them can be seen in  FIGS. 7 and 8 , are provided upon the internal peripheral wall surface portion of the lower valve housing member  114 , which effectively defines the throughbore  137 , so as to effectively serve as guide members for the vertical movement of the downwardly projecting valve stem portion  136  of the trigger-actuated control valve member  116  during its movements between its raised and lowered positions. 
     Continuing still further, the new and improved trigger-actuated control valve assembly  110  of the present invention comprises an eccentric structure in that not only does the lower valve housing member  114  having a larger diametrical extent than that of the upper valve housing member  112 , but, as can best be appreciated from  FIGS. 4 ,  5 ,  7 , and  12 , the lower valve housing member  114  is disposed in an offset or eccentric manner with respect to the upper valve housing member  112 . The reason for this is that, as can best be appreciated still further from  FIGS. 2 and 5 , when the new and improved trigger-actuated control valve assembly  110  is disposed and accommodated within the new and improved housing structure  100  of the fastener-driving tool, the offset or eccentric disposition of the lower valve housing member  114  with respect to the upper valve housing member  112  effectively creates a space within which the lower end portion of a first vertically oriented, longitudinally tapered fluid passageway  162  may effectively be defined and accommodated. The new and improved housing structure  100  of the fastener-driving tool is also provided with a trigger-actuated control valve assembly cavity  164  within which the new and improved trigger-actuated control valve assembly  110  of the present invention may be housed and accommodated, and as can best be seen from  FIGS. 2 ,  5 , and  6 , a second, substantially horizontally or radially oriented fluid passageway  166  which necessarily fluidically connects the first vertically oriented fluid passageway  162  to the trigger-actuated control valve assembly cavity  164  with proper fluid flow parameters. In other words, a substantially horizontally oriented fluid port or passage defined by means of the second, substantially horizontally or radially oriented fluid passageway  166  is needed to fluidically connect the first vertically oriented fluid passageway  162  with the trigger-actuated control valve assembly cavity  164 . 
     In accordance with the principles and teachings of the present invention, it is to be appreciated that in view of the foregoing structure comprising the various fluid passageways and cavity  162 , 164 , 166 , no complex or compound angles are incorporated within such fluid structures whereby all of such structural components can be integrally cast within the new and improved housing structure  100  of the fastener-driving tool as opposed to being drilled or machined with the inherent drawbacks as has been noted hereinbefore. In connection with the fluid flow of air within the aforenoted fluid passageways and cavity  162 , 164 , 166 , it is also to be noted that the diametrical extent of the trigger-actuated control valve assembly cavity  164  is slightly larger than the external diametrical extent of that portion of the lower flanged portion  120  of the upper valve housing member  112 , within which the windows  156 , 158  are defined so as to effectively define an annular space  168 , as can best be seen and appreciated from  FIG. 6 , and in this manner, incoming air from the external air source, not shown, can be conducted through the windows  156 , 158 , into the annular space  168 , into the second fluid passageway  166 , and upwardly within the fluid passageway  162  to the upper control air chamber of the fastener-driving tool so as to charge the upper control air chamber as desired and required, or alternatively, air to be exhausted from the upper control air chamber of the fastener-driving tool can be conducted downwardly through the first vertically oriented passageway  162 , through the second horizontally oriented passageway  166 , into the annular space  168 , and through the windows  156 , 158 . 
     It is to be lastly noted in connection with the eccentric structure comprising the new and improved trigger-actuated control valve assembly  110  of the present invention that the same need not necessarily be characterized by means of its eccentric structure, but to the contrary, it is possible that the upper and lower valve housing members  112 , 114  may be concentrically disposed with respect to each other except that the lower valve housing member  114  would still have to have a diametrical extent which would be larger than that of the upper valve housing member  112 , and that the trigger-actuated control valve assembly cavity  164  would have a similarly contoured configuration. In fact, the diametrical extent of the lower valve housing member  114  would have to be greater than that of the eccentrically mounted or disposed lower valve housing member  114 , but in any case, the lower end portion of the first vertically oriented fluid passageway  162 , as well as the second horizontally or radially oriented fluid passageway  166 , would still be able to be accommodated and cast within the new and improved housing structure  100  of the fastener-driving tool. A potentially slight drawback, however, might present itself in the form of requiring a slightly larger housing structure  100 , and therefore a slightly larger fastener-driving tool, in order to effectively enlarge the trigger-actuated control valve assembly cavity  164 , so as to accommodate the enlarged lower valve housing member  114 , while preserving predetermined wall thickness dimensions within those parts of the housing structure  100  in which, for example, the trigger-actuated control valve assembly cavity  164  is formed and defined. 
     It will of course be recalled that the new and improved trigger-actuated control valve assembly  110  comprises the upper valve spool or upper valve housing member  112  and the lower valve spool or lower valve housing member  114 , and that such valve spools or valve housing members  112 , 114  are adapted to be fixedly secured together. Accordingly, with reference lastly being made to  FIGS. 7-12 , the unique and novel manner in which the valve spool or valve housing members  112 , 114  can in fact be fixedly, yet removably, secured together will now be described. More particularly, as can best be seen and appreciated from  FIGS. 7-9 , an upstanding annular flange member  170  is disposed atop the upper surface portion of the upper annular section  124  of the lower valve housing member  114 , and a pair of diametrically opposed, arcuately configured lug members  172 , 174  are fixedly disposed upon the upper surface portion of the annular flange member  170  so as to project radially outwardly therefrom by means of a predetermined extent. In a corresponding manner, as can best be seen in  FIGS. 4 ,  7 , and  10 - 12 , the lower outer periphery of the upper valve spool or valve housing member  112  forms or defines an annular ledge member  176 . In addition, a pair of diametrically opposed, arcuately configured blocks  178 , 180  are integrally formed with, and disposed internally of, the annular ledge member  176 , and a pair of diametrically opposed, arcuately configured, upwardly recessed regions  182 ,  184  are respectively formed within end portions of the blocks  178 , 180 . 
     More particularly, it is to be appreciated that the undersurface portions  186 , 188  of the recessed regions  182 ,  184 , as considered when the new and improved trigger-actuated control valve assembly  110  is disposed in its normal upright orientation as viewed, for example, in any one of the  FIGS. 4-7 , are disposed at an elevational level which is above the elevational level at which the upper surface portion  190  of the annular ledge member  176  is disposed as disclosed within  FIGS. 6 ,  7 , and  12 , and therefore a space, for accommodating the pair of diametrically opposed lug members  172 , 174 , is effectively formed therebetween. It is further seen that the inner periphery of the annular ledge member  176  is provided with a pair of diametrically opposed, radially outwardly extending cutout regions  192 , 194  which are respectively disposed at angular or circumferential positions which correspond to the angular or circumferential positions of the recessed regions  182 , 184 . In this manner, when the upper and lower valve spool or valve housing members  112 , 114  are to be mated and assembled together, the trigger-actuated control valve member  116  is disposed within the upper and lower valve spool or valve housing members  112 , 114 , and the upper and lower valve spool or valve housing members  112 , 114  are then axially pressed together so as to effectively press the trigger-actuated control valve member  116  against the biasing force of the first coil spring member  146  thereby axially compressing the first coil spring member  146 . 
     At the same time, or substantially simultaneously therewith, the pair of oppositely disposed lug members  172 ,  174  are angularly or circumferentially aligned with and effectively inserted through the pair of diametrically opposed, radially outwardly extending cutout regions  192 , 194  so as to then be disposed within the recessed regions  182 , 184  and thereby effectively be disposed in engagement with the under-surface portions  186 , 188  of the recessed regions  182 , 184 , and subsequently, the upper valve spool or upper valve housing member  112  is rotated a predetermined angular amount in the clockwise direction with respect to the lower valve spool or valve housing member  114 , as considered when looking in the axially downward direction as viewed, for example, within  FIG. 12 . Accordingly, the pair of oppositely disposed lug members  172 , 174 , disposed upon the lower valve spool or valve housing member  114 , will be disposed, for example, within the window regions  156 , 158  of the upper valve spool or upper valve housing member  112  such that the pair of oppositely disposed lug members  172 , 174  of the lower valve spool or valve housing member  114  will effectively engage the upper surface portion  190  of the annular ledge member  176  of the upper valve spool or valve housing member  112  so as to effectively lock the upper and lower valve spool or valve housing members  112 , 114  together under the biasing force of the first coil spring member  146 . As may readily be appreciated still further, the upper and lower valve spool or valve housing members  112 , 114  may be unlocked and separated or disengaged from each other as a result of, in effect, reverse disassembly procedures. 
     Thus, it may be seen that in accordance with the principles and teachings of the present invention, there has been disclosed a new and improved trigger-actuated control valve assembly for use within a fastener-driving tool wherein a spring-biased, trigger-actuated control valve member is initially disposed internally within upper and lower valve spool or valve housing members of the trigger-actuated control valve assembly. The upper and lower valve spool or valve housing members are adapted to be fixedly mated together by means of a bayonet-type connection, defined by means of a pair of diametrically opposed dovetail lug members disposed upon the lower valve spool or valve housing member, and a gripping ledge structure defined upon the upper valve spool or valve housing member, as a result of the upper and lower valve spool or valve housing members being angularly rotated a predetermined amount with respect to each other. In this manner, the trigger-actuated control valve assembly can be pre-assembled together in a relatively quick and easy manner prior to its disposition and assembly within the fastener-driving tool housing. In addition, the trigger-actuated control valve assembly of the present invention is fluidically connected to the upper control air chamber of the fastener-driving tool by means of externally disposed air passages which do not comprise complex compound angles or orientations with respect to each other and are therefore able to be integrally cast within the fastener-driving tool housing along with a cavity for housing or accommodating the new and improved trigger-actuated control valve assembly. Fabricating the new and improved trigger-actuated control valve assembly as an eccentric structure serves to compactly accommodate the aforenoted externally disposed air passages with respect to the aforenoted trigger-actuated control valve assembly cavity. 
     Obviously, many variations and modifications of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the present invention may be practiced otherwise than as specifically described herein.