Abstract:
A solenoid valve is mounted in the bore of a ferromagnetic journal. Mounting the solenoid valve in the journal conserves space on the firewall of a vehicle where the solenoid is typically located. Journal mounting also minimizes the length of the air line necessary to supply air to the solenoid valve. Use of a ferromagnetic journal as part of the magnetic circuit allows full use of the journal bore for the components of the solenoid valve. A leak vent path is provided as well as a principal vent path in the flux flanges of the solenoid valve. The solenoid valve controls the flow of air through a seal which engages a rotating coupling of a clutch which operates a fan.

Description:
FIELD OF THE INVENTION 
     The invention is a solenoid valve mounted within the bore of a ferromagnetic journal for operating a clutch which drives an engine cooling fan. 
     BACKGROUND OF THE INVENTION 
     U.S. Pat. No. 6,092,638 to Vatsaas issued Jul. 25, 2000 discloses a spineless rotational control apparatus otherwise known as a clutch. FIG. 1 of the &#39;638 patent has been designated as prior art in the drawings of the instant invention. 
     FIG. 1 is a cross-sectional view of the prior art illustrating a clutch operated by the application of air pressure through a seal. The prior art clutch, journal and cartridge are generally indicated with reference numeral  100 . Journal  101  includes a cartridge  102 . Belt drive sheave  103  is rotatably driven by belts not shown. Belt driven sheave  103  rotates with respect to journal  101  as bearings  116  are interposed between the sheave and the journal  101 . 
     Cartridge  102  includes a seal  117 . Seal  117  engages coupling  114  for the transmission of air pressure which is available from an air supply source  106 . Cap  104  is secured to sheave  103  by a snap ring  115 . Cap  104  rotates in unison with sheave  103 . When air is supplied to the coupling  114  it is admitted into the volume as indicated by reference numeral  111 . When air pressure of sufficient magnitude exists in volume  111  friction surface  110  which is rotating in unison with sheave  103  disengages friction surface  109  which causes a fan (not shown) to stop rotating. 
     Application of air pressure to volume  11  causes clutch  105  to move leftwardly when viewing FIG. 1 of the instant application. Reference numeral  112  is an arrow indicating movement of the clutch plate  105 . Lugs  108  are mounts for a fan blade. Journal  101  is typically affixed to the engine of a large truck as indicated by aperture  107 . When the clutch is engaged approximately 125 horsepower is used to drive the fan. The fan is a cooling fan which cools the engine under certain ambient conditions. When the vehicle is operating in a cold or cool environment the cooling of the engine may be sufficient by the ambient atmosphere and/or by the operating conditions of the vehicle. When the fan is needed or when there is no air pressure available, no air is supplied to the volume defined by reference numeral  111  and the friction plates of the clutch engage. When the fan is not needed air is then supplied to the volume  111  resulting in disengagement of the friction surfaces  109  and  110 . Since the fan consumes 125 horsepower, it is desirable to operate it only when necessary thus making a clutch necessary. 
     FIG. 2 is a schematic of the prior art illustrating a solenoid  201  mounted on the fire wall  202  of a vehicle which vents the clutch. FIG. 2A is a schematic of the prior art illustrating a solenoid mounted on the fire wall of a vehicle which supplies air to the clutch. Referring to FIGS. 2 and 2A, reference numeral  200  is a schematic representation of the prior art three-way solenoid valve  201  mounted on fire wall  202 , an air line  203  interconnecting solenoid valve  201  and journal  204 , and a clutch  205 . Journal  204  is shown mounted to the engine block  206 . Solenoid valve  201  includes an air supply port labeled A and identified by reference numeral  207  and a vent port labeled B and identified by reference numeral  208 . When air is vented from clutch  205 , it must travel a considerable distance through the air line  203  and through the three-way solenoid valve  208 . Solenoid valve  201  in FIG. 2 is shown deenergized which means if electrical power is lost, clutch  205  will be vented and the fan will be engaged. FIG. 2A illustrates the condition with the solenoid valve energized and air being supplied to the journal and into the clutch for disengaging the fan. 
     The prior art has the disadvantage of having a solenoid valve remotely mounted on the fire wall  202  with respect to the journal and the clutch. Therefore, in the prior art an air compressor must be interconnected by way of an air line to port  207  on solenoid valve  201 . This solenoid valve mounted on the fire wall is then interconnected to the journal  204  mounted on the front of the engine block  206 . Therefore, the prior art requires air tubing having at least four connections. An additional disadvantage of the prior art is the capacitance of the air line  203  as indicated in FIG.  2 . By capacitance it is meant that air tubing  203  has a certain volume filled with compressed air which must be relieved before the clutch  205  may be engaged. As engine temperature sensors and measurements lag actual engine conditions, it is desirable to engage the fan relatively quickly so as to begin cooling the engine. Engagement and disengagement of the clutch is more accurately controlled with less air tubing volume. Less air tubing volume enables better control of the clutch with respect to time. The clutch can be engaged and disengaged when desired. In other words less air tubing volume optimizes control of the clutch which maximizes clutch engagement wear life. 
     Referring to FIG. 1, the principal vent is directly through coupling  114 , seal  117  and passageway  106 . Still referring to FIG. 1 the leak vent  118  is a passageway which extends through journal  101  and locking ring  119 . Considerable machining must be performed to create leakage vent  118 . The purpose of leakage vent  118  is to protect the bearings  116  from air which leaks between seal  117  and  114  and which flows into volume  120 . Pumping air through bearings  116  would contribute to more rapid oxidation of the bearings and their components. Further, pumping air through the bearings will cause loss of lubricants. 
     SUMMARY OF THE INVENTION 
     A solenoid valve is mounted in the bore of a ferromagnetic journal which is used to complete the magnetic circuit when the coil is energized. Two flux flanges are employed which together with the plunger and ferromagnetic journal complete the magnetic circuit. The diameter of each of the flux flanges is the same. The flux flange diameter is slightly smaller than the diameter of the bore in the ferromagnetic journal. Typically, the air gap between the flanges and the inside bore of the journal is one to two thousandths of an inch so as to minimize the reluctance of the air gap and thus minimize the magnetomotive force and the size and amperage of the coil. A ferromagnetic material such as carbon steel which has high permeability is preferably used as the journal material. 
     The solenoid of the instant invention includes a leakage vent path and a principal vent path. The leakage vent begins with apertures in the locking flange of an extension affixed to an adapter which in turn is affixed to the second flange. Air is supplied to a coupling when the coil is energized and any leakage from that coupling is relieved through the apertures and notches of the flanges and finally through an aperture in the housing. The principal vent allows air supplied to the clutch to be evacuated therefrom permitting the clutch plates to engage driving a powerful engine cooling fan. Air from the clutch is evacuated through passageways and bores in the stop and out of a notch in the second flange. 
     First and second flux flanges made of ferromagnetic material such as steel are employed. Overmolding secures the flux flanges to the bobbin which has the current carrying coil wound therearound. An adapter at the outlet of the stop is also overmolded to the second flange. On the inlet side of the solenoid a plug is secured to the first flange by threaded engagement or by welding. The second flange includes a stop portion which has axial and transverse bores therein. Radially spaced axially extending passageways communicate air or other fluid through the stop. 
     When the coil is energized, the plunger moves from its first position to its second position. Radially spaced axially extending passageways reside on the periphery of the plunger such that communication therebetween with the passageways of the stop is established when the coil is energized. A plug having a valve seat forms the inlet to the solenoid valve. A first elastomeric insert in the plunger interengages the valve seat of the plug prohibiting flow when the coil is deenergized and the plunger is in the first position. When the coil is energized, the first elastomeric insert and plunger move away from the valve seat of the plug opening the passageway and permitting flow of air or other fluid into and through the solenoid valve. When the coil is energized, the plunger moves to its second position. 
     When the plunger moves to its second position the second elastomeric insert therein engages the stop prohibiting air flow into the axial bore of the stop. When the plunger is urged to its first position under the influence of a spring operable between the first flux flange and the plunger, flow of air or other fluid is permitted through the axial bore and transverse bore of the stop and out of a notch in the second flux flange. Two notches exist in each flange and are spaced 180° from each other. The notches serve to aid the flow of air from the principal vent and from the leakage vent. The ferromagnetic journal is vented where the wires extend through the back side of the journal. 
     The journal mounted solenoid valve is used to control the supply of air to a clutch. When no air is supplied the clutch is engaged driving a 125 horsepower fan on a truck engine. When air is supplied to the clutch, the fan is disengaged. Bearings mounted on the ferromagnetic journal allow the rotation of a belt drive sheave. In the absence of air pressure of approximately 150 psig the belt driven sheave and clutch are rotated in unison. When the high power fan is disengaged, air is supplied to the clutch so as to separate the clutch from the sheave. When the clutch is engaged once again the air previously supplied to the clutch must be evacuated through the principal vent which includes passageways and bores in the stop. The leakage vent functions when air is supplied through the solenoid valve to the coupling. A non-rotating seal under the urging of a spring operating between a support and the seal engages a coupling which is rotating in unison with the sheave. If leakage of air occurs at the interface of the seal and the coupling then it must be evacuated. Leakage is evacuated through apertures in a locking flange, through notches in the flux flanges, through a small air gap between the flux flanges and the bore of the journal, and through an aperture in the bore to ambient atmosphere. 
     Accordingly, it is an object of the present invention to provide a solenoid valve mounted in a ferromagnetic journal and to use the ferromagnetic journal to complete the magnetic circuit. 
     It is a further object of the present invention to provide a second flux flange having an internal stop with radially spaced axially extending passageways therethrough and with axial and transverse bores. 
     It is a further object of the present invention to provide a second flux flange which includes a transverse bore. 
     It is a further object of the present invention to provide a plunger moveable between first and second positions and which includes passageways therethrough at the periphery thereof. 
     It is a further object of the present invention to provide a principal vent relieving pressure from a clutch and to provide a leakage vent for dissipating air which leaks from the seal-coupling interface when air is supplied to the clutch. 
     It is a further object of the present invention to provide a journal mounted solenoid valve for supplying air to a clutch. 
     It is a further object of the present invention to provide a solenoid valve which resides in the bore of a journal having a diameter of 1.25 inches. 
     These and other objects will be readily understood when reference is made to the Brief Description Of The Drawings, Description Of The Invention, and Claims which following hereinbelow. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional view of the prior art illustrating a clutch operated by the application of air pressure through a seal. 
     FIG. 2 is a schematic of the prior art illustrating a solenoid mounted on the firewall of a vehicle which vents the vehicle. 
     FIG. 2A is a schematic of the prior art illustrating a solenoid mounted on the firewall of a vehicle which supplies air to the clutch. 
     FIG. 3 is a cross-sectional view of the solenoid valve illustrating the coil deenergized and plunger in its first position engaging the plug. The overmolding extends through both flanges. 
     FIG. 3A is a cross-sectional view similar to FIG. 3 only a different plunger configuration is illustrated. The overmolding extends through both flanges. 
     FIG. 3B is a cross-sectional view similar to FIG. 3 illustrating the overmolding creating the plug joint interface. The overmolding extends through both flanges. 
     FIG. 4 is an enlarged portion of FIG. 3 illustrating the first insert of the plunger seated on the seat of the plug. 
     FIG. 4A is an enlarged portion of FIG. 3 illustrating the plunger spaced away from the stop as well as the axial and transverse bores in the stop. 
     FIG. 5 is a cross-sectional view similar to FIG. 3B illustrating the plunger in its second position wherein air or other fluid may be admitted through the plug, around the spring, through the passageways of the plunger, through the passageways of the stop, through the adapter, and, through the seal. 
     FIG. 6 is an enlarged portion of FIG. 5 illustrating the flow of air or other fluid past the first insert of the plunger, around the spring and through the passageways of the plunger. 
     FIG. 6A is an enlarged portion of FIG. 5 illustrating the coil energized and the plunger in its second position engaging the stop portion of the second flange prohibiting flow through its principal vent. 
     FIG. 7 is a quarter sectional perspective view of the solenoid corresponding to FIG. 3 with the coil deenergized. 
     FIG. 7A is a quarter sectional perspective view of the solenoid similar to FIG. 7 with the extension pressed onto the adapter. 
     FIG. 8 is a perspective view of the solenoid valve and the flange on the extension having apertures therein. 
     FIG. 9 is a side view of the solenoid valve illustrating notches in the first and second flanges and the transverse bore in the second flange. 
     FIG. 10 is an inlet end view of the solenoid valve illustrating notches in the flanges. 
     FIG. 11 is an outlet end view of the solenoid valve illustrating apertures in the flange of the extension. 
     FIG. 12 is a cross-sectional view of the ferromagnetic journal. 
     FIG. 13 is a cross-sectional view of the solenoid valve mounted within the ferromagnetic journal. 
     FIG. 14 is an enlarged portion of FIG. 13 illustrating the leak vent path around the flanges and out the wire aperture in the journal. 
    
    
     The drawings will be best understood when reference is made to the Description Of The Invention and Claims which follow hereinbelow. 
     DESCRIPTION OF THE INVENTION 
     FIG. 3 is a cross-sectional view of the solenoid valve illustrating the plunger  313  in its first position engaging the plug  309 . Reference numeral  300  generally designates this cross-sectional view of the solenoid valve with the coil  301  de-energized. First flux flange  303  and second flux flange  302  are illustrated in FIG.  3 . Second flux flange  302  includes a stop portion  316 . First flux flange  303  includes a threaded portion  342  for interengagement with plug  309 . Plug  309  is affixed to the first flange  303  by a mechanical joint  339  which may be threaded or welded. 
     Plunger  313  includes first elastomeric insert  314  and second elastomeric insert  315 . Elastomeric insert  314  seals against valve seat  332  when the coil is de-energized as illustrated in FIGS. 3 and 4. FIG. 4 is an enlarged portion of FIG. 3 illustrating the first elastomeric insert  314  of the plunger seated on seat  332  of the plug  309 . 
     FIG. 3A is a cross-sectional view similar to FIG. 3 only a different plunger configuration is illustrated wherein the plunger is not hollow in its center. This configuration of the plunger has slightly different magnetic properties when the magnetic circuit is considered. 
     Referring again to FIGS. 3 and 4 a spring  312  is operable between flange  303  and a lip on plunger  313 . Spring  312  urges plunger  313  and hence elastomeric insert  314  rightwardly into engagement with valve seat  332  on plug  309 . 
     Referring to FIG. 4 channels or grooves  330  and  331  comprise first and second passageways in plunger  313 . As illustrated in FIG. 4 air designated with reference numeral  404  and the letter A is not admitted to the passageways  330  and  331  because spring  312  is exerting force on plunger  313  urging first elastomeric seal  314  into engagement with plug  309 . 
     Passageways  330  and  331  are radially spaced axially extending passageways. Similarly, stop  316  includes radially spaced axially extending passageways  326  and  327 . Other passageway configurations may be used. For instance, radially spaced axially extending bores may exist through the plunger. Passageways  326  and  327  extend through the stop portion  316  of the second flange  302 . First and second flanges  303 ,  302 , plunger  313 , and stop  316  are all ferromagnetic materials which together with the ferromagnetic journal  1207  complete the magnetic circuit. Stop  316  further includes an axially extending bore  328  and a transversely extending bore  323 . Axially extending bore  328  intersects and communicates with transversely extending bore  323 . Bores  328  and  323  make up part of the path of the principal vent. 
     As illustrated in FIG. 3 which is the de-energized condition of the coil the principal permits air to be vented from the volume  111  within the clutch structure. FIG. 4A is an enlarged portion of FIG. 3 illustrating plunger  313  spaced away from the stop  316  as well as the axial  328  and transverse  323  bores in the stop  316 . Referring to FIG. 4A reference numeral  401  generally indicates the enlarged view of the stop portion of FIG. 3 illustrating the air exhaust pathway  405 . Air is exhausted along the pathway  405  as indicated by the arrows in FIG.  4 A. Reference numeral  329  as illustrated in FIG.  3  and best viewed in FIG. 4A indicates a gap between the stop  316  and plunger  313 . 
     Referring again to FIG. 3, bobbin  304  has coil  301  wound therearound. The number of turns of the coil and the amperage in the coil for a given voltage is kept low through usage of a ferromagnetic journal which completes the magnetic circuit. One of the electrical leads  334  is illustrated in FIG.  3 . First and second flux flanges  303  and  302  include radially spaced holes or apertures near the periphery thereof for the overmolding process. The holes or apertures in flange  303  secure it to the plastic  305 . Overmolding is a process which employs a plastic such as nylon or polyester  305  which is applied over parts which are secured by clamps and the like. Once the overmolding is complete, the clamps are removed and the parts are held together by the plastic which has been molded thereover. Overmolding secures the first and second flanges  303 ,  302  against bobbin  304 . Additionally, overmolding secures adapter  306  to the second flange  302 . Extension  307  is affixed to adapter  306  by a mechanical joint  338  which may be threaded or snap-fit. Extension  307  includes a locking flange  340 . Flange  340  together with snap ring  1208  secures the solenoid valve within the ferromagnetic journal as indicated in FIG.  13 . FIG. 13 is a cross sectional view of the solenoid valve mounted within ferromagnetic journal  1207 . 
     Referring again to FIG. 3 spring  317  is operable between a shoulder  318  on stop  316  and spring support  319 . Adapter  306  and extension  307  affixed thereto comprise the housing of spring  317  (which is sometimes referred to herein as the second spring  317 ) and the seal  308 . Spring support  319  includes a passageway  325  therethrough. Seal  308  also includes a passageway  324  therethrough. Seal  308  includes a keyed portion  321  which prevents rotation of the seal  308  when it engages the coupling  114  as illustrated in FIG.  1 . Seal  308  is a grade of durable graphite material and includes a front sealing surface  322  which does wear slightly when it engages coupling  114  which rotates. Seal  320  interposed between spring support  319  and seal  308  is an elastomeric seal and prevents the escape of air from the solenoid valve. 
     Referring again to FIG. 3 seal  310  is an elastomeric seal between the plug  309  and the journal  1207 . See, FIGS. 12 and 13. Seal  311  is an elastomeric seal between plug  309  and threaded portion  342  of first flange  303 . Passageway  333  and plug  309  comprise the inlet to the solenoid valve. Similarly passageways  326  and  327  in the stop  306  comprise the outlets of the solenoid valve. Passageway  324  in seal  308  may also be the outlet of the solenoid valve. Seal  335  resides between the first flange  303  and the bobbin  304  as indicated by reference numeral  335 . Correspondingly seal  336  resides between bobbin  304  and second flange  302 . Similarly a seal  337  exists between the second flange  302  and adapter  306 . 
     FIG. 3B is a cross-sectional view similar to FIG. 3 illustrating the overmolding  305  extending through both flanges. Overmolding  305  in this view forms mechanical joint connection  351  which is welded to a plug  309  directly. In this embodiment threaded interconnection  339  of the flange  303  and plug  309  illustrated in FIG. 3 is not necessary. Seals  335 ,  336 ,  337  and  350  are used to ensure that air does not migrate along the faces of flanges  303  and  302  and plastic material  305  molded over these flanges. This prevents air from entering coil  301  or the electrical leads of the coil. 
     FIG. 5 is a cross-sectional view similar view similar to FIG. 3 illustrating plunger  313  in its second position wherein air or other fluid may be admitted through the plug  309 , around the spring  312 , through the passageways  330 ,  331  of the plunger, through the passageways  326 ,  327  of the stop  316 , around second spring  317 , through the adapter  306 , and finally through the seal  308 . Arrow  501  indicates the air supply through the solenoid valve just recited. See, FIG.  5 . Reference numeral  500  generally identifies the view just explained. 
     FIG. 6 is an enlarged portion of FIG. 5 illustrating the flow of air  501  or other fluid past the first elastomeric insert  314  of plunger  313 , around spring  312  and through the radially spaced axially extending passageways  330  and  331  of plunger  313 . Valve seat  602  on plug  309  is best viewed in FIG.  6 . Reference numeral  600  generally denotes the enlarged view of the portion of FIG. 5 just explained. 
     FIG. 6A is an enlarged portion of FIG. 5 illustrating coil  301  energized and the plunger  313  in its second position engaging stop portion  316  of second flange  302  prohibiting flow through the principal vent valve. Valve seat  603  on stop  316  is best viewed in FIG.  6 A. The principal vent valve is formed by the engagement of the second elastomeric insert  315  against valve seat  603 . FIG. 6A also illustrates air flowing as indicated by arrows  501 . Reference numeral  601  identifies the enlarged view of plunger  313  and second elastomeric insert  315  acting against valve seat  603  on stop  316 . 
     FIG. 7 is a quarter sectional perspective view of the solenoid corresponding to FIG. 3 with the coil de-energized. Reference numeral  700  generally identifies the solenoid valve having notch  701  in first flux flange  303 , notch  702  in second flux flange  302  and notch  703  in first flux flange  303 . Not shown is another notch in flux flange  302  which is on the back side of the solenoid valve. FIG. 7 illustrates the principal vent pathway very well. The principal vent pathway begins at the end  322  of seal  308  and comprises passageway  324 , passageway  325  through support  319 , the passageway within and about spring  317 , passageway  327  in the stop  316 , the passageway formed by gap  329  between stop  316  and plunger  313 , axial bore  328  in the stop  316 , and finally, transverse bore  323  in stop  316 . FIG. 7A is a view similar to FIG. 7 except extension  307  is snap fit over adapter  306  and is snugly held by this snap fit. In both FIGS. 7 and 7A, the overmolded material creates a threaded mechanical connection which fastens to plug  309  and is similar to that illustrated in FIG.  3 B. 
     FIG. 8 is a perspective view  800  of the solenoid valve and flange  340  on extension  307  having apertures  704  therein. Insulation  801  is illustrated for electrical lead  334  as is insulation  802  for electrical lead  804 . The portion of the principal vent path outside of the solenoid valve is illustrated with reference numeral  803 . The leak vent path is denoted with reference numeral  805 . See, FIG.  8 . Leakage of air is vented around the exterior of the solenoid valve between the flanges and the bore of the ferromagnetic journal and through the notches. Since the notches present a larger passageway the air that is leaked from the interface of the seal  308  and coupling  114  will proceed through the notches as does the air which emanates from transverse bore  323 . The leakage vent is active only when air is being supplied through the solenoid (coil energized) and to volume  111  of the clutch mechanism. The principal vent is active only when air is not being supplied through the solenoid (coil deenergized). 
     FIG. 9 is a side view of the solenoid valve illustrating notches  701  and  702  in flanges  303  and  302 , respectively. Principal vent path  803  is also illustrated in FIG.  9 . FIG. 9 illustrates air leaking from the face  322  of seal  308  which abuts coupling  114 . FIG. 10 is an inlet end view of the solenoid valve illustrating notches  701  and  703  in first flux flange  303 . Plug  309  may be thought of as the inlet side of the solenoid valve. FIG. 11 is an outlet end view of a solenoid valve illustrating apertures  704  for the passage of leakage air through the flange  340  of the extension  308 . 
     FIG. 12 is a cross-sectional view  1200  of the ferromagnetic journal  1207 . Plug receptacle  1201  receives plug  309 . Bore  1202  has a diameter which is slightly larger than the diameter of the flux flanges  303  and  302 . The diameter of the bore  1202  is approximately two to four-thousandths of an inch greater than the diameter of flux flanges  302  and  303 . The diameter of the bore is 1.25 inches (31.75 mm) and the wall thickness is approximately 0.25 inches (6.35 mm). 
     Those skilled in the art upon reading the teachings of this disclosure will recognize that different ferromagnetic journal materials other than carbon steel may be used. Additionally, different bore diameters may be used depending on the design considerations of the magnetic circuit and the strength of the spring urging the plunger into its first position seating first insert  314  against seat  332 . Additionally, different wall thicknesses may be used depending on the permeability of the ferromagnetic material and the design considerations of the magnetic circuit. Operation of the coil at different voltages and currents will also vary depending on the number of turns of the coil and the orientation and materials used in the magnetic circuits. 
     The instant invention employs flanges having air gaps of 0.001 to 0.002 inches. Other air gaps may be used without departing from the spirit and scope of the appended claims. Use of flanges having air gaps of 0.001 to 0.002 inches facilitates assembly of the solenoid valve. To assemble the solenoid valve and mount it within a ferromagnetic journal the following steps occur. A coil  301  is wound around a plastic bobbin. The coil  301  is threaded over and through the plastic bobbin. O-ring  335  is positioned in a groove on the end of bobbin  304  and flange  303  is placed into engagement with bobbin  304 , covering both bobbin and O-ring. O-ring  336  is positioned in a groove on the other end of bobbin  304  and second flange  302  having stop  316  is placed into engagement with bobbin  304 , covering both bobbin and o-ring. At this time the flanges are held together by hand or by a clamp. O-ring  337  is positioned in a groove on adapter  306 , and the adapter is placed by hand or clamped into engagement with second flange  302 . The parts are placed within a mold. Plastic is then molded over the coil  301 , through apertures in flanges  303  and  302  and over adapter  306 . Plastic may be molded to form a threaded joint feature  339  or a welded joint feature  351 . 
     Spring  312  is interposed between ferromagnetic plunger  313  and flange  303  and the plunger is then inserted within bobbin  304 . Plug  309  is placed into engagement with the first insert  314  of the plunger and through mechanical engagement with mechanical joint feature  339  or  351 . 
     Spring  317  is inserted into the bore of adapter  306  followed by spring support  319  and elastomeric seal  320 . Seal  308  having at least two flat external surfaces is then inserted into extension  307  which includes two correspondingly flat interior surfaces so as to prevent rotation of the seal with respect to the extension. Next, extension  307  is threaded onto threads on the adapter  306 . Alternatively, the extension  307  may be pressed onto or snapped over a protrusion on the adapter  306 . 
     Aperture  1203  in journal receives the electrical adapter, insulation and conductors. Aperture  1203  serves an important function of venting the principal vent and also the leakage vent. Groove  1204  receives flange  340  of the solenoid valve. Snap ring  1208  engages flange  340  of extension  307  and secures the solenoid valve within the journal. Press-fit bearings reside upon surface  1206  of the journal. Body  1207  of the journal is carbon steel which is a ferromagnetic material having a high permeability. Air is supplied to the journal housing  1208 . Finally, journal  1200  is affixed to the front end of a truck engine block in the same manner that the prior art journal  101  is affixed to the front of a truck engine block. 
     FIG. 13 is a cross-sectional view  1300  of the solenoid valve mounted within the journal  1207 . Air supply  1301  is illustrated in FIG. 13 as being in communication with plug receptacle  1201 . Snap ring  1205  is illustrated in FIG. 13 as engaging flange  340  securing the solenoid valve within the ferromagnetic journal  1207 . 
     FIG. 14 is an enlarged portion of FIG. 13 illustrating another leak vent path around the flux flanges and out the wire aperture  1203  in the journal. Reference numeral  1400  indicates the enlarged portion of FIG.  13  and an air path is illustrated between the flanges  303 ,  302  and the bore  1202 . Referring to FIGS. 3,  8 ,  9  and  13 , air may flow in the annular area  1302  around flange  342  and communicate with opening  1203  in the journal. Notches  701 ,  702  and  703  provide high capacity for venting enabling efficient operation of the clutch. 
     Those skilled in the art will readily recognize that many changes and modifications may be made to the invention described in particularity herein without departing from the spirit and scope of the appended claims.