Pump and overflow valve assembly

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

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] FIG. 1 is a perspective view of a paint spraying apparatus useful in the practice of the present invention.

[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] 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] FIG. 3 b is a section view similar to that of FIG. 3a, except with the position switch in a second position, and the control switch in a second or ON position.

[0026] FIG. 3 c is a section view similar to that of FIG. 3b, except with the position switch in a third position with the control switch in the second, ON, position.

[0027] FIG. 4 is a section view taken along line IV-IV of FIG. 3b showing the position switch and the control switch.

[0028] FIG. 5 is a section view taken along line V-V of FIG. 3b showing the position switch.

[0029] FIG. 6 is a diagrammatic view of the operation of the position switch.

[0030] FIG. 7 is a fragmentary section view taken along line VII-VII of FIG. 3b with parts removed showing mating portions of an adapter and feed pump housing.

[0031] FIG. 8 is an exploded perspective view of the pump and overflow valve assembly.

[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] FIGS. 3 a -3c 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. 3a) 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 6a, 6b of the valve housing 6 are connected together in the form of a screw connection 6c. 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. 3c) and there is increased fluid pressure in the return line 4 acting on the surface 7a 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. 3a -3c 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. 3a).

[0037] A distal end portion 11a 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 11a 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 14a 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 14b of the pin 14 in assembled condition. An external thread 18 is provided on the head end portion 14b 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. 3a-3c 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. 3a-3c there are illustrated three operating positions I, II, III of the overflow valve 5 and the pump motor 62. In FIG. 3a, 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. 3b, 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. 3c, 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. 3b. 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. 3a-3c).

[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. 3a-3c) 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. 3a and 6) and the second position (II) (FIGS. 3b 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. 3c 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. 3c).

[0046] As can be seen in FIGS. 3a and 5, the free end 11a 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 11a of the joining piece 11. As may be seen most clearly in FIGS. 3a -3c 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 11a. 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] 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. 3b 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. 3a 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 11a 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.

Claims

1. 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 said feed pump; an overflow valve disposed in said return line, said overflow valve comprising a valve body and a valve housing, at least part of said valve housing being disposed in the feed pump housing; a spring disposed between said valve housing and said valve body for biasing said valve body toward a closed position; an adapter mounted on the feed pump housing; ajoining member fixed to said valve body and projecting outwardly from said valve housing; a rotatable position switch mounted on said adapter and provided with a circumferential contact surface; and feed pump controlling means disposed in said adapter and responsive to selected rotation and positioning of said position switch to control operation of said overflow valve and said pump.

2. The assembly in accordance with claim 1, wherein said joining piece is provided with a locating hole in an end portion of said joining piece disposed in the position switch, and a pin is locked into said position switch and extends perpendicularly to a longitudinal axis of the joining piece, and projects through the locating hole in said joining piece.

3. The assembly in accordance with claim 2, wherein a free end of the pin is held in a blind hole disposed in said position switch, a head piece of the pin being screwed into an internal thread provided in the position switch blind hole.

4. The assembly in accordance with claim 2 wherein said position switch, when rotated, causes the valve body to be moved axially.

5. The assembly in accordance with claim 1 wherein said position switch is provided with at least two control surfaces, and wherein said adapter is provided with cams having surfaces complementary to the control surfaces of the position switch.

6. The assembly in accordance with claim 1 wherein said adapter and said position switch are removable separately and together from the housing of the feed pump.

7. The assembly in accordance with claim 1 wherein an accommodation opening is provided in the housing of the feed pump to retain said adapter in place and prevent said adapter from rotating.

8. The assembly in accordance with claim 7, wherein said adapter is provided with an external contour complementary to the shape of the accommodation opening.

9. The assembly in accordance with claim 1 wherein said adapter comprises a plurality of housing components.

10. The assembly in accordance with claim 9, wherein a first of said housing components is provided with a projection defining a through-hole provided for passage therethrough of said overflow valve, the projection projecting towards a second of said housing components when said housing components are assembled, and said second housing component is provided with a recess adapted to receive an external contour of the projection.

11. The assembly in accordance with claim 9, wherein said housing components are attached to each other.

12. The assembly in accordance with claim 1 wherein a cross section of a free end portion of said joining member is of a shape corresponding to a blind hole in said position switch.

13. The assembly in accordance with claim 12, wherein the cross sectional shape in the blind hole of said position switch is configured such that said joining member is held in a predetermined position in said position switch.

14. The assembly in accordance with claim 12, wherein a connector portion of said position switch is provided with a control surface and wherein the connector portion is insertable into said adapter, and wherein when said position switch is assembled, the control surface is in contact with a mating surface provided in said adapter.