Abstract:
A control valve system having a housing defining a first inlet, a second inlet, a first outlet, a second outlet, and an exhaust to define an intrinsically safe double valve. The double control valve system of the present invention further includes a pair of cross exhaust passages that eliminates the need for complicated timing devices.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to control valves and, more particularly, relates to a double valve having a cross exhaust capable of replacing two separate valves.  
         BACKGROUND OF THE INVENTION  
         [0002]    Machine tools of various types operate through a valving system, which interacts with a pneumatically controlled clutch and/or brake assembly. For safety reasons, the control valves that are used to operate these machine tools require the operator to actuate two separate control signal applying contacts essentially simultaneously. This requirement of simultaneous application ensures that the operator will not have his hand near the moving components of the machine tool when an operating cycle is initiated. The two-control signal applying contacts can then be connected to the valving system that allows compressed air to be delivered to the machine tool to perform its operating cycle.  
           [0003]    Safety rules and regulations require the valving system to be designed such that if a component in the valving system malfunctions, the valving system will not allow additional movement of the machine tool. In addition, the valving system must ensure that a new operation cycle of the machine tool cannot be initiated after a component of the valving system has become defective.  
           [0004]    Prior art electromagnetic valving systems, which are utilized for the operation of machine tools, meet these safety requirements through the use of a double valve assembly. The double valve assembly includes two electromagnetic supply valves that are normally closed. Each of the supply valves is moved to an open position in response to an electrical control signal. The two supply valves are arranged in series with respect to the source of compressed air.  
           [0005]    The double valve assembly also includes two exhaust valves, which are normally open. Each exhaust valve is closed by a respective supply valve when it is opened. It is therefore necessary for the supply valves to be opened simultaneously, otherwise supply air will be exhausted from the system through one of the exhaust valves. The opening and closing of the valve units is monitored by sensing air pressures in the respective valve units and then comparing these two pressures. The monitoring and comparing of these two pressures are accomplished by using a single air cylinder that is separated into two chambers by a piston. The pressure in each valve unit is delivered to one of the chambers. Thus, unequal pressures in the valve units will cause movement of the normally static piston, which will then interrupt the electrical signal to one of the valve units. This and other external electronic monitoring arrangements are expensive and require that electrical signal processing equipment be designed and utilized.  
           [0006]    The continued development of the valving systems for machine tools has been directed toward more reliable, simpler, and less costly valving systems that both meet and exceed the safety performance requirements in force today as well as those proposed for the future.  
         SUMMARY OF THE INVENTION  
         [0007]    According to the principles of the present invention, a control valve system is provided that includes a housing defining a first inlet, a second inlet, a first outlet, a second outlet, and an exhaust to define an intrinsically safe double valve. The double control valve system of the present invention further includes a pair of cross exhaust passages that eliminates the need for complicated timing devices.  
           [0008]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0010]    [0010]FIG. 1 is a cross-sectional view of the control valve system shown in its normal position ready for operation;  
         [0011]    [0011]FIG. 2 is a cross-sectional view of the control valve system shown in an abnormal position; and  
         [0012]    [0012]FIG. 3 is a cross-sectional view of the control valve system shown in its fully operated position with the outlet being fully pressurized; 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0013]    The following description of the preferred embodiment is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0014]    Referring now to the drawings in which like reference numerals designate like or corresponding parts throughout the several views, there is shown in FIGS.  1 - 3  a control valve system in accordance with the present invention, which is designated generally by the reference numeral  10 . Control valve system  10  is shown as a fluid control valve.  
         [0015]    Referring to FIG. 1, control valve system  10  comprises a housing  12  having a first fluid inlet fluid passage  14 , a second fluid inlet fluid passage  16 , a first fluid first outlet fluid passage  18 , a second fluid outlet fluid passage  20 , a fluid exhaust fluid passage  22 , a first valve bore  24 , a second valve bore  26 , a first fluid reservoir  28 , and a second fluid reservoir  30 . Disposed within first valve bore  24  is a first valve member  32  and disposed within second valve bore  26  is a second valve member  34 . Located within first inlet fluid passage  14  in a coaxial relationship with first valve member  32  is a third valve member  36 . Located within second inlet fluid passage  16  in a coaxial relationship with second valve member  34  is a fourth valve member  38 . A pair of solenoid valves  40  and  42  is attached to housing  12 .  
         [0016]    A plurality of fluid passages interconnect valve bores  24  and  26  with first inlet fluid passage  14 , second inlet fluid passage  16 , first outlet fluid passage  18 , second outlet fluid passage  20 , exhaust fluid passage  22 , first fluid reservoir  28 , second reservoir  30 , third valve member  36 , and fourth valve member  38 . A fluid passage  44  extends between first inlet fluid passage  14  and an intermediate chamber  46  formed by first valve bore  24 . A fluid passage  48  extends between second inlet fluid passage  16  and an intermediate chamber  50  formed by second valve bore  26 .  
         [0017]    A fluid passage  52  extends between intermediate chamber  46  and first reservoir  28 . A restrictor  54  is disposed within fluid passage  52  to limit the amount of fluid flow through fluid passage  52 . Additionally, a fluid passage  56  extends between first reservoir  28  and a lower chamber  58  formed by first valve bore  24 . Similarly, a fluid passage  60  extends between intermediate chamber  50  and second reservoir  30 . A restrictor  62  is disposed within fluid passage  60  to limit the amount of fluid flow through fluid passage  60 . Additionally, a fluid passage  64  extends between second reservoir  30  and a lower chamber  66  formed by second valve bore  26 .  
         [0018]    Furthermore, a fluid passage  68  extends between fluid passage  52  and the input to solenoid valve  42 . A fluid passage  70  extends between fluid passage  60  and the input to solenoid valve  40 . A fluid passage  72  extends between the output of solenoid valve  40  and an upper chamber  74  formed by first valve bore  24 . A fluid passage  76  extends between the output of solenoid valve  42  and an upper chamber  78  formed by second valve bore  26 .  
         [0019]    A cross passage  80  extends between the lower portion of intermediate chamber  46  and the upper portion of intermediate chamber  50 . A cross passage  82  extends between the lower portion of intermediate chamber  50  and the upper portion of intermediate chamber  46 . A fluid passage  84  extends between cross passage  80  and second outlet fluid passage  20 . A fluid passage  86  extends between cross passage  82  and first outlet fluid passage  18 .  
         [0020]    First outlet fluid passage  18  is in communication with exhaust fluid passage  22  through a lower port  88  and an upper port  90 . Similarly, second outlet fluid passage  20  is in communication with exhaust fluid passage  22  through a lower port  92  and an upper port  94 . A reset fluid passage  96  extends into housing  12  and is in communication with the lower portions of lower chamber  58  and lower chamber  66  by communicating with fluid passage  56  and fluid passage  64 , respectively. A pair of check valves  98  and  100  are disposed between reset fluid passage  96  and fluid passage  56  and fluid passage  64 , respectively, to prohibit fluid flow between fluid passage  56  or fluid passage  64  to reset fluid passage  96 , but allow fluid flow from reset fluid passage  96  to one or both fluid passages  56  and  64 . A reset solenoid  102  is further provided in communication with a supply inlet fluid passage  104  from second inlet fluid passage  16  and reset fluid passage  96 .  
         [0021]    A first valve body or member  106  is disposed within first valve bore  24  and a second valve body or member  108  is disposed within second valve bore  26 . First valve member  106  comprises an upper piston  110 , an intermediate piston  112 , and a lower piston  114 , all of which move together as a single unit. Upper piston  110  is disposed within upper chamber  74  and includes a first valve seat  116  that opens and closes upper port  90  located between an intermediate chamber  118  of first valve bore  24  and exhaust fluid passage  22 . Upper piston  110  further includes a second valve seat  120  that opens and closes lower port  88  located between first outlet fluid passage  18  and intermediate chamber  118 .  
         [0022]    Intermediate piston  112  is disposed within intermediate chamber  46  and includes an annular fluid passage  122  which fluidly connects fluid passage  44  to fluid passage  52  when intermediate piston  112  is seated against housing  12 .  
         [0023]    Lower piston  114  is located within lower chamber  58  and includes a seal  124  that seals lower chamber  58  from first inlet fluid passage  14 .  
         [0024]    Second valve member  108  comprises an upper piston  126 , an intermediate piston  128 , and a lower piston  130 , all of which move together as a single unit. Upper piston  126  is disposed within upper chamber  78  and includes a first valve seat  132  that opens and closes upper port  94  located between an intermediate chamber  134  of second valve bore  26  and exhaust fluid passage  22 . Upper piston  126  further includes a second valve seat  136  that opens and closes lower port  92  located between second outlet fluid passage  20  and intermediate chamber  134 .  
         [0025]    Intermediate piston  128  is disposed within intermediate chamber  50  and includes an annular fluid passage  138 , which fluidly connects fluid passage  48  to fluid passage  60  when intermediate piston  128  is seated against housing  12 .  
         [0026]    Lower piston  130  is located within lower chamber  66  and includes a seal  140  that seals lower chamber  66  from second inlet fluid passage  16 .  
         [0027]    Third valve member  36  comprises an inner member  142  slidably disposed in first valve bore  24 , a valve seat  144  surrounding inner member  142 , and a valve spring  146 . Inner member  142  includes a shoulder portion  148 , which acts as a contact feature with intermediate piston  112  and a contact feature with valve seat  144 . Valve spring  146  biases valve seat  144  into contact with inner member  142  and further biases valve seat  144  against housing  12  to prohibit fluid flow between first inlet fluid passage  14  and intermediate chamber  46 . Inner member  142  is further capable of being in driving contact with lower piston  114 .  
         [0028]    Fourth valve member  38  comprises an inner member  150  slidably disposed in second valve bore  26 , a valve seat  152  surrounding inner member  150 , and a valve spring  154 . Inner member  150  includes a shoulder portion  156 , which acts as a contact feature with intermediate piston  128  and a contact feature with valve seat  152 . Valve spring  154  biases valve seat  152  into contact with inner member  150  and further biases valve seat  152  against housing  12  to prohibit fluid flow between second inlet fluid passage  16  and intermediate chamber  50 . Inner member  150  is further capable of being in driving contact with lower piston  130 .  
         [0029]    A first cross exhaust fluid passage  158  extends between first outlet fluid passage  18  and intermediate chamber  134 . A second cross exhaust fluid passage  160  extends between second outlet fluid passage  20  and intermediate chamber  118 . First cross exhaust fluid passage  158  and second cross exhaust fluid passage  160  permit exhausting of first outlet fluid passage  18  and second outlet fluid passage  20 , respectively, in the event control valve system  10  malfunctions, thus providing an intrinsically safe valve.  
       Operation  
       [0030]    [0030]FIG. 1 illustrates control valve system  10  in its deactuated position. Pressurized fluid from first inlet fluid passage  14  biases valve seat  144  against housing  12 , thereby closing communication between first inlet fluid passage  14  and intermediate chamber  46 . Upon actuation of reset solenoid  102 , pressurized fluid from first inlet fluid passage  14  is provided to fluid passage  44 , to fluid passage  52  through annular fluid passage  122 , through restrictor  54  and first reservoir  28 , and into lower chamber  58  to bias first valve member  106  upward to seat intermediate piston  112  against housing  12 . Pressurized fluid also flows through fluid passage  52  and through fluid passage  68  to the inlet of solenoid valve  42 .  
         [0031]    In a similar manner, pressurized fluid from second inlet fluid passage  16  biases valve seat  152  against housing  12 , thereby closing communication between second inlet fluid passage  16  and intermediate chamber  50 . Furthermore, pressurized fluid from second inlet fluid passage  16  is provided to fluid passage  48 , to fluid passage  60  through annular fluid passage  138 , through restrictor  62  and second reservoir  30 , and into lower chamber  66  to bias second valve member  108  upward to seat intermediate piston  128  against housing  12 . Pressurized fluid also flows through fluid passage  60  and through fluid passage  68  to the inlet of solenoid valve  40 .  
         [0032]    First outlet fluid passage  18  and second outlet fluid passage  20  are in communication with exhaust fluid passage  22  due to second valve seat  120  and first valve seat  116  being biased upward opening lower port  88  and upper port  94 , respectively, and second valve seat  136  and first valve seat  132  being biased upward opening lower port  92  and upper port  94 , respectively. Furthermore, first outlet fluid passage  18  is in communication with intermediate chamber  134  through first cross exhaust fluid passage  158  and second outlet fluid passage  20  is in communication with intermediate chamber  118  through second cross exhaust fluid passage  160 . Intermediate chamber  46  and intermediate chamber  50  are also open to exhaust fluid passage  22  through cross passages  80  and  82 , respectively, through fluid passages  84  and  86 , respectively. The fluid pressure below upper piston  110  and upper piston  126  of first valve member  106  and second valve member  108 , respectively, bias first valve member  106  and second valve member  108  upward maintaining control valve system  10  in the deactuated position. The connection between fluid passage  44  and fluid passage  52  through annular fluid passage  122  and the connection between fluid passage  48  and fluid passage  62  through annular fluid passage  138  maintain fluid pressure within lower chamber  58  and lower chamber  66  and first reservoir  28  and second reservoir  30 .  
         [0033]    [0033]FIG. 2 illustrates control valve system  10  in its actuated position. Both solenoid valve  40  and solenoid valve  42  have been substantially simultaneously actuated. The actuation of solenoid valve  40  connects fluid passage  70  and to fluid passage  72 . Pressurized fluid is directed into upper chamber  74  to move first valve member  106  downward. The diameter of upper piston  110  is larger than the diameter of lower piston  114 , thus causing the load that moves first valve member  106  downward. In a similar manner, the actuation of solenoid valve  42  connects fluid passage  68  and to fluid passage  76 . Pressurized fluid is directed into upper chamber  78  to move second valve member  108  downward. The diameter of upper piston  126  is larger than the diameter of lower piston  130 , thus causing the load that moves second valve member  108  downward. When first valve member  106  moves downward, intermediate piston  112  contacts and drives downward inner member  142  of third valve member  36 , thereby causing shoulder portion  148  to unseat valve seat  144 . Similarly, second valve member  108  unseats valve seat  152 .  
         [0034]    Pressurized fluid flows from first inlet fluid passage  14  into the lower portion of intermediate chamber  46 , through cross passage  80  to the upper portion of intermediate chamber  50 , and through a gap  162  between second valve member  108  and housing  12  to provide pressurized fluid to second outlet fluid passage  20 . Pressurized fluid from first inlet fluid passage  14  also flows through fluid passage  84  to second outlet fluid passage  20 .  
         [0035]    In a similar manner, pressurized fluid flows from second inlet fluid passage  16  into the lower portion of intermediate chamber  50 , through cross passage  82  to the upper portion of intermediate chamber  46 , and through a gap  164  between first valve member  106  and housing  12  to provide pressurized fluid to first outlet fluid passage  18 . Pressurized fluid from second inlet fluid passage  16  also flows through fluid passage  86  to first outlet fluid passage  18 .  
         [0036]    The movement of first valve member  106  and second valve member  108  downward seats valve seats  116  and  120  and valve seats  132  and  136  against housing  12  to close ports  88  and  90  and ports  92  and  94  to isolate first outlet fluid passage  18  from exhaust fluid passage  22  and second outlet fluid passage  20  from exhaust fluid passage  22 . It should be recognized that this arrangement further seals first cross exhaust fluid passage  158  from venting first outlet fluid passage  18  and second cross exhaust fluid passage  160  from venting second outlet fluid passage  20 . The fluid pressure within first reservoir  28  and reservoir  30  will initially be reduced when solenoid valve  40  and solenoid valve  42  are actuated but the fluid pressure will return to the supply pressure of first inlet fluid passage  14  and second inlet fluid passage  16 .  
         [0037]    Still referring to FIG. 2, control valve system  10  may optionally includes a pair of washers or restrictors  166  and  168 . Specifically, inlet washer  166  is disposed within the fluid path of inlet fluid passage  16 . Inlet washer  166  includes at least one through orifice that is sized to restrict inlet flow. Similarly, outlet washer  168  is disposed within the fluid path of outlet fluid passage  20 . Outlet washer  168  similarly includes at least one through orifice that is sized to restrict outlet flow. More particularly, the through orifices of inlet washer  166  and outlet washer  168  are sized to establish an overlap adjustment or timing setting. For example, this overlap adjustment preferably enables the disengagement of a brake member prior to engagement of a clutch member and vice versa to prevent unnecessary wear on the machine. Because of the timing capability of this washer arrangement, it is possible to eliminate the need for a check valve to prevent backflow.  
         [0038]    [0038]FIG. 3 illustrates control valve system  10  in an abnormal position. Second valve member  108  is located in its upward position while first valve member  106  is located in its lower position. Both solenoid valve  40  and solenoid valve  42  are located in their deactuated position. Pressurized fluid from second inlet fluid passage  16  is provided to fluid passage  48 , to fluid passage  60  through annular fluid passage  138 , through restrictor  62  and second reservoir  30 , and into lower chamber  66  to bias second valve member  108  upward to seat intermediate piston  128  against housing  12 . Pressurized fluid also flows through fluid passage  60  and through fluid passage  68  to the inlet of solenoid valve  40  through fluid passage  70 . Second outlet fluid passage  20  is in communication with exhaust fluid passage  22  due to second valve seat  136  and first valve seat  132  being biased upward opening lower port  92  and upper port  94 , respectively.  
         [0039]    First valve member  106  is located in its lower position which opens various fluid passages to first outlet fluid passage  18 , which because second cross exhaust fluid passage  160 , is open to exhaust  22 . The upper portion of intermediate chamber  46  is open to exhaust  22  through gap  164 . Pressurized fluid from first inlet fluid passage  14  is bled to exhaust  22  through fluid passage  44  and through the upper portion of intermediate chamber  46  through gap  164 , through first cross exhaust fluid passage  158 , through upper port  94  to exhaust fluid passage  22 . In addition, pressurized fluid from first inlet fluid passage  14  will bleed to exhaust  22  by entering the lower portion of intermediate chamber  46 , flow through cross passage  80 , through fluid passage  84 , through second outlet fluid passage  20 , through upper port  94  and into exhaust fluid passage  22 . Pressurized fluid in fluid passage  52  and thus lower chamber  58  is also bled to exhaust through restrictor  54 , which removes the biasing being applied to first valve member  106 . A leak path also exists from first inlet fluid passage  14  to the lower portion of intermediate chamber  46  to the upper portion of intermediate chamber  46  via a gap between intermediate piston  112  and the walls of first valve bore  24 . From the upper portion of intermediate chamber  46 , fluid pressure may escape as described above. Yet another leak path exists from the lower portion of intermediate chamber  46  through cross passage  80 , from upper portion to lower portion of intermediate chamber  50 , and through cross passage  82  into upper portion of intermediate chamber  46 . From the upper portion of intermediate chamber  46 , fluid pressure may escape as described above. In addition, fluid pressure in first reservoir  28  is bled to exhaust through restrictor  54  removing the pressurized fluid being supplied to solenoid valve  42  through fluid passage  68 . The amount of time for lower chamber  58  and first reservoir  28  to bleed to exhaust will depend upon the size of lower chamber  58 , first reservoir  28 , and restrictor  54 . With the release of pressurized air from upper chamber  74  above upper piston  110  and the presence of pressurized air within first inlet fluid passage  14  acting against the bottom of valve seat  144 , valve spring  146  will move first valve member  106  to an intermediate position where valve seat  144  is seated against housing  12  but intermediate piston  112  is not seated against housing  12  (not shown).  
         [0040]    When valve seat  144  urges first valve member  106  upwards due to the biasing of valve spring  146 , valve seat  144  pushes against shoulder portion  148  to move first valve member  106 . Because of a lost motion attachment between valve seat  144  and upper piston  110 , when valve seat  144  engages housing  12 , intermediate piston  112  has not yet engaged housing  12 . Additional movement of first valve member  106  is required to seat intermediate piston  112  against housing  12  and connect fluid passage  44  to fluid passage  52  and provide pressurized fluid to first reservoir  28  and lower chamber  58 . Without the seating of intermediate piston  112  to housing  12 , the upper portion of intermediate chamber  46  and thus fluid passages  40  and  52  are open to exhaust  22  through gap  164 , first cross exhaust fluid passage  158 , and upper port  94 . Thus, first reservoir  28  is open to exhaust along with fluid passage  68  and the input to solenoid valve  42 . Lower chamber  58  is also open to exhaust, thus eliminating any biasing load that would urge first valve member  106  upward to seat intermediate piston  112  against housing  12 .  
         [0041]    When it is desired to move control valve system  10  from its locked out position to its deactuated position shown in FIG. 1, pressurized fluid is supplied to reset fluid passage  96 . Pressurized fluid being supplied to reset fluid passage  96  opens check valve  98  due to the pressure differential and pressurized fluid fills first reservoir  28  and lower chamber  58 . Restrictor  54  will limit the amount of fluid bled off to exhaust during the resetting procedure. Once first reservoir  28  and lower chamber  58  are filled with pressurized fluid, the fluid within lower chamber  58  acts against upper piston  110  to move first valve member  106  upward to seat intermediate piston  112  against housing  12 . Fluid passage  44  is again in communication with fluid passage  52  through annular fluid passage  122  and control valve system  10  is again positioned in its deactuated position as shown in FIG. 1.  
         [0042]    While the above description of FIGS. 1 through 3 have been described with first valve member  106  being located in its intermediate and locked out position and second valve member  108  being located in its deactuated position, it is to be understood that a similar locked out position of control valve system  10  would occur if first valve member  106  were located in its deactuated condition and second valve member  108  were located in its intermediate and locked out condition. The resetting procedure of applying pressurized fluid to reset fluid passage  96  would cause the pressurized fluid to open check valve  100  to fill second reservoir  30  and lower chamber  66 . The pressurized fluid in lower chamber  66  would lift second valve member  108  to seat intermediate piston  128  against housing  12  reconnecting fluid passage  48  with fluid passage  60 .  
         [0043]    Thus, control valve system  10  is a fully fluid operating valve system that has the capability of sensing an abnormal condition and responding to this abnormal condition by switching to a locked out condition, which then requires an individual to go through a resetting operation before control valve system  10 , will again function.  
         [0044]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.