Abstract:
A pump and overflow valve assembly for a fluid pumping system includes a feed pump disposed in a feed pump housing, a return line in communication with the feed pump, an overflow valve disposed in the return line, the valve including a valve body and a valve housing being disposed in the feed pump housing. A spring is disposed between the valve housing and the valve body, and ajoining member is fixed to the valve body and projects outwardly from the valve housing. An adapter is mounted on the feed pump housing and a position switch is rotatably mounted on the adapter and provided with a control surface. Feed pump controlling means are disposed in the adapter and are responsive to selective rotation of the position switch to control operation of the overflow valve and the pump.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This is a continuation-in-part of U.S. patent application Ser. No. 09/826,086, filed Apr. 4, 2001, titled DEVICE FOR ACTUATING AN OVERFLOW VALVE naming Leopold Von Keudell as Inventor, and the entire contents of which are hereby incorporated by reference. This application claims priority through Ser. No. 09/826,086 to German application 200 08 051.2, filed May 4, 2000. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to fluid pumping systems, and more particularly to a pump and overflow valve assembly, including means for actuating the overflow valve, in particular an overflow valve incorporated in a return line of feed pump. The overflow valve comprises a valve housing and a valve body, the valve housing being disposed in a fixed position in a housing of the feed pump. A compression spring is arranged between the valve housing and the valve body of the overflow valve, and a joining piece is attached to the valve body and projects from the valve housing. The joining piece is in communication with a position switch for controlling the feed pump. The position switch is connected to the joining piece by an adapter mounted in the housing of the feed pump.  
           [0004]    2. Description of the Prior Art  
           [0005]    When feed pumps, in particular diaphragm pumps, are taken into operation, the fluid should be held in the feed lines of the feed pump without pressure so that the feed pump can start up without feed output in starting mode. For this purpose, it is necessary that some of the fluid which is going to be pumped by the feed pump be pumped out of return lines after the feed pump has been switched off, with this evacuation pumping lasting until the feed pressure has been reduced. Consequently, an overflow valve is provided in the return line, by means of which the excess pressure line is to be opened both in the event of excess pressure during operation of the feed pump and when the pump is switched off and on, such that there is no feed pressure in the feed line.  
           [0006]    Such a device is described in U.S. Pat. No. 4,928,722, incorporated herein by reference, in which a position switch is provided with a circumferential cam track which acts axially on a switching button of the control switch for the feed pump. This means the electrical power switch of the feed pump is actuated by rotation of the position switch. The overflow valve is moved axially at the same time by the rotation of the position switch. This axial movement of the overflow valve occurs because the position switch possesses an internal cam track by means of which an axial movement is induced when the position switch is rotated. The valve body of the overflow valve and its joining piece are connected to the position switch.  
           [0007]    With this device, it has been proven to be a disadvantage that the control system for the electrical power to the motor of the feed pump cannot be reliably actuated because the overflow valve must be held in an open or a closed position by the position switch at the same time as the electrical power switch of the motor has to be held ON by the position switch. The fact that the position switch has to be transferred into different variable axial positions means that the cam track of the control switch of the motor has to satisfy exacting requirements. Accordingly, the position switch is expensive to manufacture.  
           [0008]    Also, achieving a seal between the housing of the feed pump and the position switch involves considerable difficulties because the axial movement of the control switch prevents the use of a reliable seal, such as an o-ring seal.  
           [0009]    Furthermore, separating the mechanical axial adjustment mechanism of the overflow valve from the electrical power control of the feed pump is not a technically elegant solution because the spatial separation and the axial actuation of the control switch for the motor place great demands on the design and configuration of the position switch. This means that considerable time has to be expended when changing the overflow valve, and also that the operating personnel have to cope with more exacting demands in order to be able to assemble and dismantle these components.  
           [0010]    In feed pumps of the prior art, the position switch which actuates the overflow valve from outside is arranged in the housing of the pump separately from the electrical switch which controls the pump motor. The position switch not only switches the overflow valve but also the electric power for the feed pump. Frequently, however, the overflow valve is arranged in the housing in such a way that the forces for moving the overflow valve have to be absorbed by the position switch or its housing.  
         SUMMARY OF THE INVENTION  
         [0011]    Accordingly, the purpose of the present invention is to provide a pump and overflow valve assembly including means for actuating the valve in such a way that both the axial adjustment of the overflow valve and the actuation of the electrical control of the feed pump are undertaken using a common housing, and wherein procedures for assembling and dismantling the components of the device can be carried out quickly and easily.  
           [0012]    In accordance with the present invention, this task is accomplished in that electrical, pneumatic, hydraulic and/or mechanical components for controlling the feed pump are arranged inside an adapter, and in that these components can be actuated by the position switch using a control surface extending circumferentially around the position switch.  
           [0013]    Torque for axial movement of the valve body is transmitted between the position switch and the overflow valve by means of a locating hole disposed in the end of the joining piece assigned to the position switch. A pin is locked in the position switch and extends perpendicularly to the longitudinal axis of the joining piece and projects through the locating hole in the joining piece.  
           [0014]    Due to the fact that at least two control surfaces are installed in the position switch and run at an angle in the circumferential direction of the position switch, and that cams corresponding to the control surfaces of the position switch are disposed on the adapter, it is assured that the overflow valve can be moved to various positions by the position switch in relation to the axial direction of the overflow valve, which means that mechanical connection between the position switch and the joining piece of the overflow valve enables the required operating mode of the overflow valve to be selected or set. At the same time, the position switch also controls the electric switch arranged in the adapter, which means the rotation of the position switch can be used for setting the operating mode of the feed pump in relation to the position of the overflow valve.  
           [0015]    There is an oval or polygonal accommodation opening in the housing of the feed pump in order to absorb the torque present in the adapter and the position switch and to lock the adapter in place to prevent it from rotating, so that the torque which occurs is directly transmitted into and absorbed by the housing of the feed pump.  
           [0016]    In the arrangement of the adapter on the housing of the feed pump in accordance with the present invention, it is an advantage that the overflow valve is arranged without play and is not in contact with the adapter. As a result, there is no force transmission between the overflow valve and the adapter. Instead, this process occurs directly within the housing of the feed pump, because the valve housing is screwed into the housing of the feed pump. The position switch only transmits the axial forces of the spring onto the adapter.  
           [0017]    A configuration of this type significantly facilitates assembly and dismantling of the adapter, the overflow valve, and the position switch, for example, in comparison to the design according to the prior art, because the individual components can be removed separately or together from the housing of the feed pump.  
           [0018]    The electrical switch arranged in the adapter is needed for controlling the feed pump and is not affected when the adapted is removed, because the electrical circuit elements are mounted in a fixed position in the adapter and are only connected to the pump in the housing of the feed pump by means of an electrical control cable. This ensures it is a quick and simple matter to dismantle or assemble the individual components, namely the adapter, the overflow and position switch together with the electric switch fitted in the adapter.  
           [0019]    In summary, with the above objects in view, a feature of the present invention is the provision of a pump and overflow valve assembly for a fluid pumping system, the assembly comprising a feed pump disposed in a feed pump housing, a return line in communication with the feed pump, an overflow valve disposed in the return line, the valve comprising a valve body and a valve housing, the valve housing being disposed in the feed pump housing. A spring is disposed between the valve housing and the valve body and a joining member is fixed to the valve body and projects outwardly from the valve housing. An adapter is mounted on the feed pump housing and a position switch is rotatably mounted on the adapter and provided with control surfaces. Feed pump controlling means are disposed in the adapter and are responsive to selective rotation and positioning of the position switch to control operation of the overflow valve.  
           [0020]    The above and other features of the invention, including various novel details of construction and combination parts, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular device embodying the invention is shown by way of illustration only and not as a limitation of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention.  
           [0021]    Reference is made to the accompanying drawings in which is shown an illustrative embodiment of the invention, from which its novel features and advantages will be apparent. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]    [0022]FIG. 1 is a perspective view of a paint spraying apparatus useful in the practice of the present invention.  
         [0023]    [0023]FIG. 2 is an enlarged, fragmentary, partially cutaway view of a portion of the apparatus shown in FIG. 1, to illustrate the pump and motor associated with the present invention.  
         [0024]    [0024]FIG. 3 a  is a section view of a pump and overflow valve assembly, including an overflow valve, joining piece, adapter, position switch, control switch and a portion of a feed pump illustrative of an embodiment of the invention, with the position switch in a first position and the control switch in a first or OFF position.  
         [0025]    [0025]FIG. 3 b  is a section view similar to that of FIG. 3 a,  except with the position switch in a second position, and the control switch in a second or ON position.  
         [0026]    [0026]FIG. 3 c  is a section view similar to that of FIG. 3 b,  except with the position switch in a third position with the control switch in the second, ON, position.  
         [0027]    [0027]FIG. 4 is a section view taken along line IV-IV of FIG. 3 b  showing the position switch and the control switch.  
         [0028]    [0028]FIG. 5 is a section view taken along line V-V of FIG. 3 b  showing the position switch.  
         [0029]    [0029]FIG. 6 is a diagrammatic view of the operation of the position switch.  
         [0030]    [0030]FIG. 7 is a fragmentary section view taken along line VII-VII of FIG. 3 b  with parts removed showing mating portions of an adapter and feed pump housing.  
         [0031]    [0031]FIG. 8 is an exploded perspective view of the pump and overflow valve assembly.  
         [0032]    [0032]FIG. 9 is a circuit diagram for the apparatus shown in FIG. 1, useful in the practice of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0033]    Referring to the Figures, most particularly to FIG. 1, a paint spraying apparatus  50  useful in the practice of the present invention may be seen. Apparatus  50  may include a paint hopper  52  or other means for delivering paint to a pump and motor assembly  54  which will pressurize the paint and deliver it to a spray gun  56  via a high pressure hose  58 . Apparatus  50  utilizes an electric motor connected to a power cord set  60 .  
         [0034]    Referring now to FIG. 2, the pump and motor assembly  54  includes an electric motor  62  which powers a feed pump  2  having a diaphragm  64 . Pump  2  also includes a piston  66  driven by an eccentric  68 , which is rotated via drive belt assembly  70  connected to motor  62 .  
         [0035]    [0035]FIGS. 3 a - 3   c  and FIG. 8 show an assembly or device  1 , including an overflow valve  5  arranged in a return line  4  of the feed pump  2 . The overflow valve  5  comprises a two-part valve housing  6  and valve body  7  (FIG. 3 a ) which is shown in an open position so that the return line  4  is clear. The two-part valve housing  6  is preferably screwed into a housing  3  of the feed pump  2 . Both parts  6   a,    6   b  of the valve housing  6  are connected together in the form of a screw connection  6   c.  A compression spring  8  is arranged between the valve housing  6  and the valve body  7  to ensure normal valve control in the operating mode of the feed pump  2 . Consequently, if valve  7  is closed, (as shown in FIG. 3 c ) and there is increased fluid pressure in the return line  4  acting on the surface  7   a  of the overflow valve  5  facing away from the valve body  7 , then the overflow valve  5  is opened irrespective of its setting and the excess pressure in the normal feed circuit of the feed pump  2  is dissipated because the overflow value  5  is open.  
         [0036]    An adapter  9  (FIGS. 3 a  - 3   c  and FIG. 8) is supported against the housing  3  of the feed pump  2  and is provided with a through hole or aperture  10  in which is disposed a portion of a position switch  12  having therein a bore  22  for accommodating a joining piece  11  fitted to the valve body  7 . As a result, the joining piece  11  projects through the adapter  9 , beyond the open end of the hole  10  (FIG. 3 a ).  
         [0037]    A distal end portion  11   a  of the joining piece  11  is held in the position switch  12 . A mechanical connection between the position switch  12  and the joining piece  11  includes a locating hole  13  provided in the area of the distal end portion  11   a  of the joining piece  11  and a pin  14  projecting through the locating hole  13  of the joining piece  11  perpendicular to the longitudinal axis of the joining piece  11 . A distal end  14   a  of the pin  14  is held in a blind hole  15  in the position switch  12 . In addition, the position switch blind hole  15  is provided with a threaded portion  17  which receives a head end portion  14   b  of the pin  14  in assembled condition. An external thread  18  is provided on the head end portion  14   b  of the pin  14  so that the pin  14  is screwed into the position switch  12  and is therefore firmly locked into it.  
         [0038]    Referring to FIGS. 3 a - 3   c  and  4 , it will be seen that an electrical switch  16  features a nose or mechanical contact  20  spring-biased by a coil spring  19  into engagement with a connector portion  37  of a control surface  38 . Electrical wires  36  are connected to electrical contacts (not shown, but within switch  16 ) to selectively provide electrical power from a power source (not shown) to a motor  62  for pump  2  fluidly connected to the return line  4 . The movable switch contact  20  is maintained in continuous engagement with the connecting portion  37 . The electrical switch  16  is operated between the OFF and ON electrical conditions when the connecting portion  37  of position switch  12  is manually rotated. It is to be understood that nose  20  acts like a cam follower and is operated or moved between OFF and ON positions in response to the cam-like surface of connecting portion  37  and control surface  38 . Switch  16  is OFF when contact  20  is engaged with flat control surface  38 , and switch  16  is ON when contact  20  is engaged with a cylindrical part of the connecting portion  37 .  
         [0039]    In FIGS. 3 a - 3   c  there are illustrated three operating positions I, II, III of the overflow valve  5  and the pump motor  62 . In FIG. 3 a,  the position switch  12  is disposed in a shut-off position (I), wherein the valve  5  is open and the pump motor  62  receives no energy. At this time nose  20  of electrical switch  16  is allowed to move to a first position by contact with connector surface  38  to maintain the switch  16  in an OFF condition. In FIG. 3 b,  the position switch  12  is in the second position (II) in which the flat control surface  38  of the connector  37  moves out of contact with the switch contact  20 , urging nose  20  of switch  16  to move to actuate switch  16  to an ON electrical condition and position. It to be understood that in the second position (II) of the position switch  12 , the pump motor  62  receives electrical energy and therefore operates, but the valve  5  is still open and the pumped fluid goes into the return line  4 . As will be described hereinafter, electrical power to motor  62  may be controlled by switch  16  acting through a relay or motor starter. The second position (II) corresponds to a bypass or priming condition for the pump  2 . In FIG. 3 c,  the position switch  12  is in the third position (III) in which the cylindrical part of connector portion  37  is in contact with the switch  16  in the same condition as shown in FIG. 3 b.  The electrical switch  16  has a pair of internal contacts closed in this condition, corresponding to an electrical ON condition, providing electrical power to the pump motor, causing the pump to be in operation. In this instance, the overflow valve  5  is closed and the fluid is transported through an operational line or hose  58  under high pressure. The cylindrical part of connector portion  37  stays engaged with the electrical contact  20  in the positions II and III, such that the pump motor receives operating power during both positions II and III.  
         [0040]    Referring to FIG. 6, it will be seen that the position switch  12  includes the previously described bore  22  for receiving the joining piece  11 . The reference characters I, II and III illustrate the three positions of the position switch  12  when rotated. The level between positions I and II is equal (i.e., unchanged). The level of position III is removed from the level of positions I and II. The rise of the slope between positions II and III defines an axial distance which is equal to the distance x through which the valve can be moved (FIGS. 3 a - 3   c ).  
         [0041]    Accordingly, when the position switch  12  is moved from position I to position II the pump motor  62  starts, as noted above, but the valve  5  remains open, so the pumped fluid simply circulates through the return line  4 .  
         [0042]    When the position switch  12  is moved to position III, the motor  62  and pump  2  continue in operation and the valve  5  closes, blocking the return line  4  and causing the pumped fluid, under pressure, to flow through the operational line  58  to spray gun  56 .  
         [0043]    In accordance with FIGS. 4 and 5, the position switch  12 , when the assembled condition possesses four ribs  31  which incline in the direction of the adapter  9 . Each rib  31  forms a control surface  32  running at an angle. The ribs  31  are evenly spaced circumferentially of the position switch  12  and are arranged symmetrically in relation to the transverse axis of the position switch  12 . This means both halves of the position switch are configured identically to one another, so that the position switch  12  can be connected to the adapter  9  in two positions.  
         [0044]    Two cams  33  (FIGS. 3 a - 3   c ) on the adapter  9  extend towards the position switch  12 , and the control surfaces  32  of the ribs  31  are held against the cams  33 . The inclined control surfaces  32 , acting in conjunction with the rotation of the position switch  12 , ensure that the joining piece  11  connected to the position switch  12  effects axial movement.  
         [0045]    When the position switch  12  is turned, in addition to controlling electrical power to the pump motor  62 , the position switch  12  also affects the operation of the overflow valve  5 . In moving between the first position (I) (FIGS. 3 a  and  6 ) and the second position (II) (FIGS. 3 b  and  6 ), the distance between the valve and its shut-off position is not changed because the level of the position switch  12  is not changed. However, when the position switch  12  is turned to the third position (III) (FIGS. 3 c  and  6 ), relative axial movement between the cams  33  and the control surfaces  32  of the ribs  31  allow movement of the overflow valve a distance sufficient to effect closure of the return line  4  (FIG. 3 c ).  
         [0046]    As can be seen in FIGS. 3 a  and  5 , the free end  11   a  of the joining piece  11  is provided with a non circular cross section  28  which is configured and acts in conjunction with the bore  22  of the position switch  12  in such a way that the joining piece  11  can be introduced into the locating hole  10  of the position switch  12 , with the result that the locating hole  13  of the joining piece  11  can be aligned with the blind hole  15  for the pin  14 , locking the joining piece  11  within the position switch  12 . Non-circular cross section  28  may be one or more flat surfaces formed on the free end  11   a  of the joining piece  11 . As may be seen most clearly in FIGS. 3 a  - 3   c  and FIG. 5, an extension region  21  of bore  22  is preferably congruently shaped in cross section and formed to closely interfit with the non circular cross section of free end  11   a.  The pin  14  can be pushed through the locating hole  13  after the joining piece  11  has been introduced into the position switch  12 .  
         [0047]    Furthermore, the non-circular cross section  28  guarantees that the overflow valve  5  can be attached in a defined position in the position switch  12 , so that the position switch  12 , together with the electric switch  16  inside the adapter  9 , permit both the feed pump  2  and the overflow valve  5  to be controlled.  
         [0048]    [0048]FIGS. 7 and 8 show an oval-shaped accommodation opening  23  for retaining the adapter  9 , the opening  23  being disposed in the housing  3  of the feed pump  2  (FIGS. 3 b  and  8 ). The adapter  9  has a mating surface or joining element  24  congruent to opening  23 . Element  24  is inserted into the opening  23  to form a non-rotating connection. The oval configuration of the accommodation opening  23  means the adapter  9  cannot rotate with respect to the housing  3 .  
         [0049]    As can be seen most clearly in FIGS. 3 a  and  8 , the adapter  9  is made up of two housing components  34 ,  35  which can be fixed to one another and secured to the housing  3  of the feed pump  2  by means of fastening bolts  27  which pass through the adapter  9 . The adapter  9  may be attached to the housing  3  of the feed pump  2  irrespective of the locking mechanisms for both housing components  34  and  35 . Furthermore, centering pins (not shown) can be provided on the adapter  9  extending towards the housing  3 , so that the adapter can be attached to the housing  3  in a predetermined position.  
         [0050]    The electrical switch  16  for the feed pump  2  is provided within the two housing components  34  and  35 . The electrical switch  16  is connected to control motor  62  of the feed pump  2  by means of the electrical wires  36 . As such, the position switch  12  controls both the electrical switch  16  provided in the adapter  9  and the position of the overflow valve  5 .  
         [0051]    The overflow valve  5  is assembled in such a way that a part of the valve housing  6  is screwed into the housing  3  of the feed pump  2 . The overflow valve  5  is inserted into the outwardly open housing part of the valve housing  6  and the compression spring  8  is inserted. The second housing part of the valve housing  6  is screwed onto the first part of the valve housing  6 , so that the overflow valve  5  is firmly locked into the housing  3  of the feed pump  2  by means of the valve housing  6 . In this arrangement, the joining piece  11  of the overflow valve  5  projects out of the housing  3  of the feed pump  2 . The through-hole  10  in the adapter  9  accommodates the joining piece  11  of the overflow valve  5 . The fastening bolts  27  are used for bolting the two components of the adapter  9  onto the housing  3  of the feed pump  2 .  
         [0052]    The joining piece  11  projects from the adapter  9  and the position switch  12  is connected onto the joining piece  11 . The non-circular cross section  28  (FIG. 7) on the distal end  11   a  of the joining piece  11  permits the position switch  12  to be connected to it in a defined fashion. In order to attach the position switch  12  onto the joining piece  11 , the pin  14  is pushed into the blind hole  15  provided for it within the position switch  12  and projects through the joining piece  11  by way of the locating hole  13 . The threads  18  provided on the pin  14  lock the pin  14  into the position switch  12 . Furthermore, the position switch  12  includes the connecting portion  37  projecting towards the adapter  9 , with the connector portion  37  having a flat or cam surface  38  on its side which serves as the control surface  38 . The corresponding congruent non-circular surface  21  in the hole  22  definitively determines a position of the position switch  12  with respect to the joining piece  11 .  
         [0053]    Referring now to FIG. 9, a circuit diagram  72  for the paint spraying apparatus  50  may be seen. Switch  16  is shown in the OFF condition in diagram  72 . When switch  16  is moved from the position shown, connection is made between leads  74  and  76  of electrical wires  36 , providing power to a coil  78  of a load relay  80 . Load relay  80  has contacts  82  controlled by coil  78 , such that when coil  78  is powered, contacts  82  provide “mains” power from an electrical mains plug  84  to motor  62 . It is to be understood that when mains power is present, a second relay  86  will be powered, closing its related contacts, to complete the circuit between lead  76  and coil  78 .  
         [0054]    It will be understood that many additional changes in the details, materials, steps and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principles and scope of the invention as expressed in the appended claims.