WO2005080841A1

WO2005080841A1 - High-speed three-way fluid solenoid valve and relative production method

Info

Publication number: WO2005080841A1
Application number: PCT/IB2005/000370
Authority: WO
Inventors: Mario Gaiardo
Original assignee: Matrix S.P.A.
Priority date: 2004-02-12
Filing date: 2005-02-10
Publication date: 2005-09-01
Also published as: ITTO20040076A1

Abstract

The solenoid valve (5) has a valve body (6), in turn having an inlet conduit (12), a user conduit (13), and an exhaust conduit (14), which are parallel to one another and all come out on the same side (18) of the valve body (6). A compartment (9) in the valve body (6) houses a plate (24) forming the armature of an electromagnet (17). Two shutter disks (22, 23) for the inlet and exhaust conduits (12, 14) are fixed to the same face (27) of the plate (24). The plate (24) oscillates about an edge (58) of a pole surface (42) of the magnetic circuit (32) of the electromagnet (17), on which the plate is held by two bars (53) of elastic material. The valve body (6) has two half-shells (7, 8) of plastic material, one (7) of which has the conduits (12-14), and the other of which is molded with the electromagnet (17) as an insert. The electromagnet (17) is powered by two electric plugs (45) extending through at least one hole (47) in the other half-shell (8). And an electronic board (76), for controlling the electromagnet (17), may be fixed inside a recess (77) of the other half-shell (8).

Description

HIGH-SPEED THREE-WAY FLUID SOLENOID VALVE AND RELATIVE PRODUCTION METHOD TECHNICAL FIELD The present invention relates to a high-speed three- way solenoid valve for a fluid at other than ambient pressure, and to a relative production method. BACKGROUND ART Three-way solenoid valves comprise a fluid inlet conduit, e.g. for pressurized or low-pressure air; a user conduit using the fluid; and an exhaust conduit at ambient pressure. In the case of pressurized air, this may be used to control a corresponding device actuator. In the case of low-pressure air, this may be used to control a suction device for medical skin treatment. In both types of solenoid valve, the response time of the movable assembly with respect to the electric control signal is vital, both when opening and closing the solenoid valve, and in fact is what determines maximum switch frequency of the solenoid valve. Solenoid valves of the above type are known in which the three valve conduits are parallel, and the movable assembly comprises an electromagnet armature defined by an oscillating metal plate. The plate has two shutters on its two opposite faces to alternatively open and close the inlet conduit and the exhaust conduit. The exhaust conduit and inlet conduit are therefore substantially aligned but must come out on opposite sides of the valve body. Though switching time is satisfactory, known solenoid valves of this sort have the drawback that the device being controlled must have two different portions at which the corresponding conduits come out, so that fluidtight connection of the solenoid valve is relatively complicated. Moreover, solenoid valves of this type are of fairly considerable height on account of the two coaxial conduits. Three-way solenoid valves are also known in which the three conduits come out on the same side of the valve body, e.g. a flat surface. The inlet and outlet conduit shutters are carried by a slide controlled by an electromagnet, and which must move perpendicular to the two conduits, so that a fairly considerable amount of travel is involved. Moreover, at each switch, opening and closing of the two conduits are necessarily gradual, so that the control pulse on the device is sinusoidal, thus further increasing the response time of the solenoid valve. The slide therefore requires a very powerful control electromagnet, and the switch frequency of the solenoid valve is relatively low. DISCLOSURE OF INVENTION It is an object of the present invention to provide a three-way solenoid valve of high switch frequency, which is easy to connect to the device for control, and which eliminates the drawbacks of known solenoid valves.

It is a further object of the invention to provide a method of producing the solenoid valve much more cheaply. According to the present invention, there is provided a high-speed three-way solenoid valve for a fluid at other than ambient pressure, the solenoid valve comprising a valve body having an inlet conduit, a user conduit, and an exhaust conduit, said conduits being parallel to one another and communicating with a compartment of said valve body; the solenoid valve also comprising shutter means housed in said compartment and activated to alternatively close said inlet conduit and said exhaust conduit, said shutter means being carried by an armature of an electromagnet; and the solenoid valve being characterized in that said conduits all come out on an outer side of said valve body; said shutter means being movable in a direction substantially parallel to said conduits. More specifically, the fluid is low-pressure air, and the inlet conduit is connected to air intake means, so that operation of the armature generates suction along the user conduit. According to the present invention, there is also provided a method of producing a three-way solenoid valve having a valve body comprising two half-shells connected in fluidtight manner and enclosing a compartment housing an armature of an electromagnet; a first of said half- shells having conduits for said fluid; the other of said half-shells comprising a cavity for housing said electromagnet, and a seat for housing a bush containing an elastic member acting on said armature; the method being characterized by comprising the steps of: - injecting plastic material into a first mold to form said first half-shell with said conduits; - preparing said electromagnet and said bush with said elastic member; - placing said electromagnet as an insert inside a second mold; - injecting plastic material into said second mold with said insert to form said other half-shell having said seat; - force-fitting said bush with said elastic member inside said seat; - placing said armature inside said compartment, and inserting a seal between said half-shells; and - connecting said half-shells to each other by means of fast-fit connecting members. BRIEF DESCRIPTION OF THE DRAWINGS A preferred, non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows a view in perspective of a high-speed three-way solenoid valve in accordance with the invention; Figure 2 shows a larger-scale half-section of the Figure 1 solenoid valve; Figure 3 shows a section along line III-III in Figure 2; Figure 4 shows the Figure 3 section with parts removed; Figure 5 shows a section along line V-V in Figure 2; Figures 6 and 7 show two half-sections of two half- shells of the valve body. BEST MODE FOR CARRYING OUT THE INVENTION Number 5 in Figure 1 indicates as a whole a highspeed three-way solenoid valve for a fluid at other than ambient pressure, and for generating suction. Solenoid valve 5 comprises a substantially parallelepiped-shaped valve body 6 defined by two opposite, preferably rectangular, half-shells 7 and 8, which enclose a compartment 9 (Figure 2) and are connected to each other in fluidtight manner along a plane M. For which purpose, half-shell 7 has a groove 10 in which is inserted a seal 11 (see also Figures 3 and 4) . Solenoid valve 5 comprises a conduit 12, hereinafter referred to as an inlet conduit, communicating with a fluid pressure difference generator. Solenoid valve 5 also comprises a fluid user conduit 13; and a conduit 14, hereinafter referred to as an exhaust conduit, communicating with the outside. Conduits 12-14 are parallel, and communicate through compartment 9, which houses shutter means indicated as a whole by 16 and activated by a control electromagnet 17 to alternatively close inlet conduit 12 and exhaust conduit 14. Solenoid valve 5 according to the invention may be used for controlling compressed air, e.g. for controlling a corresponding actuator of a device defined by a compression pump, as well as for controlling low-pressure air. The embodiment described, however, is particularly suitable for controlling low-pressure air, e.g. of a suction device for medical skin treatment. The low- pressure air is generated by a suction or vacuum pump not shown in the drawings . According to one characteristic of the invention, valve body 6 comprises an outer side 18 defined by the outer or top surface of half-shell 7. Conduits 12-14 are carried by half-shell 7 and all come out on the same side 18 of valve body 6. Each conduit 12-14 is defined by a corresponding sleeve 19-21 formed in one piece with half- shell 7 and projecting outwards of compartment 9. Each sleeve 19-21 permits fast connection of a corresponding tube 19' -21" of flexible material - indicated by a dash line in Figure 2 - to connect solenoid valve 5 to the treatment device. Sleeves 19-21 are preferably the same length, and therefore come out in a plane parallel to plane M. Half-shell 7 is advantageously defined by a substantially rectangular plate 25 supporting sleeves 19- 21. Plate 25 also supports in one piece an oblong lateral wall 30 for protecting sleeves 19-21. More specifically, conduits 12-14 and respective sleeves 19-21 have respective axes lying in a plane P (see also Figure 4) perpendicular to plane M. The axis of user conduit 13 is equidistant from the axis of inlet conduit 12 and the axis of exhaust conduit 14. Alternatively, the axis of user conduit 13 may be parallel to, but apart from, plane P, and/or need not be equidistant from the axes of conduits 12 and 14. Shutter means 16 comprise two shutter members in the form of shutter disks 22 and 23 of elastic material, which engage the inner edges of respective conduits 12 and 14. Disks 22 and 23 move substantially in a direction D parallel to the axes of conduits 12 and 14, and are carried by a lever defined by a plate 24 made of ferromagnetic material and substantially parallel to plane M. Plate 24 oscillates about a fulcrum 26 parallel to plane M, and constitutes the armature of electromagnet 17. More specifically, plate 24 comprises a face 27 facing half-shell 7, an opposite face 28 facing half- shell 8, and two lever arms 29 and 31 (Figure 3) on opposite sides of fulcrum 26. Shutter disks 22 and 23 are fixed in known manner, e.g. glued or cured, to the same face 27 of plate 24, but to opposite arms 29 and 31. Half-shell 8 is defined by another plate 35 having a contoured surface and formed in one piece with a lateral wall 37 of the same shape and size as plate 25 of half- shell 7. Electromagnet 17 comprises a magnetic circuit defined by a U-section body 32 of magnetic material. Body 32 comprises a bottom portion 33 formed in one piece with two parallel arms 34 and 36 (see also Figure 5) . Arm 36 forms the core of an electric winding 41 of electromagnet 17, and is thicker than arm 34. Arms 34 and 36 of body 32 terminate with respective coplanar pole surfaces 42 and 43 of electromagnet 17. Electromagnet 17 is housed inside a cavity 39, of plate 37 of half-shell 8, closed at the bottom by a wall 40. Electric winding 41 is energized by two electric plugs 45 - only one shown in Figure 2 - which extend through corresponding holes 47 in half-shell 8, and come out through wall 40 of cavity 39, as explained in detail later on. Fulcrum 26 of plate 24 is defined by two bars 53 of elastic material (see also Figures 3 and 4), which are axially aligned and housed inside two grooves 54 of two appendixes 56 on the inner side of half-shell 7. Bars 53 engage face 27 of plate 24, which is normally held resting on an edge 58 of pole surface 42 of arm 34, so that plate 24 actually oscillates about edge 58. In the embodiment shown, the axes of the two grooves 54 are aligned vertically with edge 58, i.e. said axes and edge 58 lie in the same transverse plane T perpendicular to planes M and P. The axes of bars 53 therefore also lie in the same plane T, thus minimizing friction produced by rotation of plate 24. Plate 24 also has two lateral slots 59 (Figure 5) which engage two corresponding projections 61 carried by appendixes 56 of half-shell 7 and adjacent to the two grooves 54. Projections 61 lock bars 53 axially and prevent plate 24 moving along plane M. And plate 25 of half-shell 7 has two appendixes 62 for accurately guiding arm 29 of plate 24 laterally. Plate 24 is normally pushed by elastic means into the Figure 2 position, in which shutter disk 22 rests on the edge of inlet conduit 12, thus cutting off low- pressure air intake. More specifically, said elastic means comprise a helical compression spring 66 housed inside a bush 67, which is force-fitted inside a seat defined by a dead hole 68 in half-shell 8. At one end, bush 67 has a hole 69 in which slides a push rod 71, which acts on a portion 72, substantially opposite shutter disk 22, of face 28 of plate 24 (see also Figure 5) . At the other end, bush 67 is closed by a wall 74, which is removable to permit insertion of spring 66, which is thus precompressed between wall 74 and an end 73 of push rod 71. To activate electromagnet 17 at maximum frequency, the control pulse can be modulated to obtain a predetermined voltage pattern, in which the leading edge slope is increased. The control pulse, known as a speedup control pulse, is modulated by a known electronic circuit, which, according to one aspect of the invention, is formed on an electronic board 76 housed in a recess 77 in the outer underside surface of half-shell 8. More specifically, board 76 is connected electrically to the two plugs 45 of winding 41, is fixed, e.g. glued, to bottom wall 40 of cavity 39, and is connected electrically in known manner to a normal electric power supply by control means of the low-pressure-air user device. In actual use, three-way solenoid valve 5 is connected to the user device by simply connecting flexible tubes 19 '-21' to sleeves 19-21. When electromagnet 17 is energized, plate 24 rotates about edge 58 of arm 34, in opposition to spring 66, to position shutter disk 23 against the edge of exhaust conduit 14, which is thus closed; while shutter disk 22 is detached from the edge of inlet conduit 12, thus connecting compartment 9 with the suction pump. The suction skin treatment device is therefore operated by means of user conduit 13, sleeve 20, and flexible tube 20'. When electromagnet 17 is deenergized, spring 66 resets plate 24 rapidly to the Figure 2 position, thus closing inlet conduit 12 and opening exhaust conduit 14. By way of example, in low-pressure conditions of up to -0.8 bar with respect to ambient pressure, and with inlet and exhaust conduits 12 and 14 of about 7 mm in diameter and 20 to 25 mm apart, a spring 66 with a 350- 550 g work load may be used, and an electromagnet 17 generating a 1500-2000 g force of attraction on plate 24. Plate 24 may be designed with a movable assembly of 4-8 g mass. In numerous tests of such a solenoid valve 5, an open and close response time of less than 4 ms and a frequency of over 100Hz were obtained. The valve body 6 of such a solenoid valve 5 may be less than 70 mm in length, less than 40 mm in height, and extremely compact in width, by appropriately designing plate 24 and electromagnet 17. In the case of a solenoid valve 5 for compressed air, half-shell 7 may have no sleeves 19-21 and no lateral wall 30, so that side 18 of valve body 6 is perfectly flat for easy fluidtight connection to a corresponding flat surface of the user device. In which case, for compressed air at 10-12 bar pressure, and with inlet and exhaust conduits 12 and 14 of about 3 mm in diameter and 20 to 25 mm apart, a spring 66 with a 700- 950 g work load may be used, and an electromagnet 17 generating a 1500-2000 g force of attraction on plate 24. Plate 24 may be designed with a movable assembly of 3-4 g mass. In numerous tests of such a solenoid valve 5, an open and close response time of less than 1 ms and a frequency of over 150Hz were obtained. Endurance tests of solenoid valves 5 as described above show an average working life of the solenoid valve of over 100 million operations, as compared with an average working life of 1-10 million operations of known slide-type solenoid valves of similar capacity. According to another aspect of the invention, solenoid valve 5 as described above can be mass produced cheaply on automatic machines. For which purpose, half- shell 7 has four holes 78 (Figure 4), and half-shell 8 has four holes 79 (Figure 5) . By aligning holes 78 with holes 79, connection therebetween may be made using respective fast-fit connecting members, such as self- threading rivets 80 suitable for the plastic material of half-shells 7 and 8, and which are inserted inside holes 78, 79 by means of an appropriate device. The method of producing solenoid valve 5 comprises the following steps. Firstly, plastic material is injected into a first mold to form a first half-shell 7 with conduits 12-14 and relative sleeves 19-21. Electromagnet 17 and bush 67 with push rod 71 and precompressed spring 66 are prepared separately. Electromagnet 17 is placed as an insert inside a second mold, and plastic material is injected into the second mold with said insert to form the other half-shell 8 with seat 68 for bush 67. After bush 67 is force-fitted inside seat 68, both armature 24 with bars 53 and seal 11 are inserted between half-shells 7 and 8. And finally, half-shells 7 and 8 are connected by inserting self-threading rivets 80 inside holes 78 and 79. The method may also comprise the steps of fixing an electronic board 76, for controlling electromagnet 17, to half-shell 8, and connecting electronic board 76 electrically to the winding of electromagnet 17. The advantages, as compared with known solenoid valves, of three-way solenoid valve 5 according to the invention will be clear from the foregoing description. Particularly advantageous is minimizing command response time, and therefore switch time, of solenoid valve 5, which is mainly achieved by minimizing friction and mass of the movable assembly of electromagnet 17. Moreover, switch frequency and the working life of solenoid valve 5 can be increased. Solenoid valve 5 also provides for minimizing the distance between shutter disks 22, 23, and the time taken to connect solenoid valve 5 to the compressed-air- controlled actuator or to the suction user device. The height and width and the number of component parts of solenoid valve 5 can be minimized. Finally, production and assembly time, and therefore the overall cost, of solenoid valve 5 are also minimized. Clearly, changes may be made to the solenoid valve as described herein without, however, departing from the scope of the accompanying Claims. For example, changes may be made to the form of electromagnet 17 and plate 24, and to connection of shutter disks 22, 23 to plate 24. The two bars 53 of fulcrum 26 may be so arranged as to produce a certain amount of torque on plate 24 with respect to edge 58, so as to reduce the force of, or eliminate, spring 66. Since exhaust conduit 14 communicates with the outside, relative sleeve 21 may be eliminated in certain applications. Half-shells 7 and 8 may also be connected otherwise than as described. And, finally, electronic control circuit board 76 may be separate from the body of solenoid valve 5.

Claims

1) A high-speed three-way solenoid valve for a fluid at other than ambient pressure, the solenoid valve comprising a valve body (6) having an inlet conduit (12) , a user conduit (13), and an exhaust conduit (14), said conduits (12-14) being parallel to one another and communicating with a compartment (9) of said valve body (6); the solenoid valve also comprising shutter means (16) housed in said compartment (9) and activated to alternatively close said inlet conduit (12) and said exhaust conduit (14), said shutter means (16) being carried by an armature (24) of an electromagnet (17) ; and the solenoid valve being characterized in that said conduits (12-14) all come out on an outer side (18) of said valve body (6); said shutter means (16) being movable in a direction substantially parallel to said conduits (12-14) . 2) A solenoid valve as claimed in Claim 1, characterized in that said armature is defined by a lever

(24) made of ferromagnetic material and oscillating about a fulcrum (26); said shutter means (16) comprising two shutter members (22, 23) carried by said lever (24) on two arms (29, 31) on opposite sides of said fulcrum (26) . 3) A solenoid valve as claimed in Claim 2, characterized in that at least said inlet conduit (12) and said exhaust conduit (14) are positioned with their respective axes lying in a plane (P) parallel to said direction. 4) A solenoid valve as claimed in Claim 3, characterized in that the axis of said user conduit (13) also lies in said plane (P) , and is equidistant from the axes of said inlet conduit (12) and said exhaust conduit (14). 5) A solenoid valve as claimed in Claim 3 or 4, characterized in that said lever (24) is normally pushed by elastic means (66) into such a position as to close said inlet conduit (12) and open said exhaust conduit (14); said electromagnet (17) being energized to rotate said lever (24), in opposition to said elastic means (66), into such a position as to open said inlet conduit (12) and close said exhaust conduit (14) . 6) A solenoid valve as claimed in Claim 5, characterized in that said lever is defined by a plate (24) substantially perpendicular to said plane (P) ; said fulcrum (26) being parallel to said plate (24); and said electromagnet (17) comprising a pole surface (43) which acts on the arm (29) of said plate (24) connected to the shutter disk (22) of said inlet conduit (12) . 7) A solenoid valve as claimed in Claim 6, characterized in that said valve body (6) comprises two half-shells (7, 8) connected in fluidtight manner to each other along a further plane (M) perpendicular to said plane (P) , and enclosing said compartment (9) ; a first of said half-shells (7, 8) having said conduits (12-14); and said electromagnet (17) being housed in a cavity (39) of the other of said half-shells (7, 8) . 8) A solenoid valve as claimed in Claim 7, characterized in that said fulcrum (26) comprises an edge (58) of a further pole surface (42) of said electromagnet (17); at least one bar (53) of elastic material being provided to keep said plate (24) resting on said edge (58) . 9) A solenoid valve as claimed in Claim 8, characterized in that said fulcrum (26) comprises two bars (53) of elastic material housed in two axially aligned grooves (54) on said first half-shell (7) . 10) A solenoid valve as claimed in Claim 9, characterized in that the axis of said grooves (54) and said edge (58) lie in the same transverse plane (T) , which is perpendicular to said plane (P) of the axes of said conduits (12-14) . 11) A solenoid valve as claimed in Claim 10, characterized in that said first half-shell (7) comprises a rectangular plate (25) integral with a lateral wall (30) ; said grooves (54) being carried by two appendixes (56) integral with said plate (25) ; said appendixes (56) having two corresponding lateral projections (61) substantially aligned with said grooves (54); and said lateral projections (61) engaging two opposite slots (59) of said plate (24) . 12) A solenoid valve as claimed in one of Claims 7 to 11, characterized in that said elastic means comprise a spring (66) housed in said other half-shell (8) and acting on said plate (24) at the shutter disk (22) of said inlet conduit (12) . 13) A solenoid valve as claimed in Claim 12, characterized in that said spring is a compression spring (66) housed inside a bush (67); said compression spring (66) acting on said plate (24) via a push rod (71) sliding inside said bush (67) . 14) A solenoid valve as claimed in one of the foregoing Claims, characterized in that said fluid is low-pressure air; said inlet conduit (12) being connected to air intake means, so that operation of said armature (24) generates suction along the user conduit (13) . 15) A solenoid valve as claimed in Claims 11 and 14, characterized in that at least one of said conduits (12- 14) has a corresponding sleeve (19-21) integral with said plate (25) and projecting from said side (18) outwards of said valve body (6) ; said lateral wall (30) protecting said sleeve (19-21) . 16) A solenoid valve as claimed in Claim 15, characterized in that said inlet conduit (12) and said user conduit (13) comprise an inlet sleeve (19) and a user sleeve (20) respectively; said sleeves (19, 20) being connected rapidly to corresponding tubes (19', 20') of flexible plastic material for said suction means and for a user device respectively. 17) A solenoid valve as claimed in Claim 15 or 16, characterized in that said electromagnet (17) is powered by electric plugs (45) housed in at least one hole (47) in said other half-shell (8); said hole (47) being parallel to said conduits (12-14) . 18) A solenoid valve as claimed in Claims 11 and 17, characterized in that said other half-shell (8) comprises a contoured plate (35) integral with a lateral wall (37) of the same shape as the plate (25) of said first half- shell (7) ; said contoured plate (35) comprising said cavity (39), and a seat (68) for said bush (67). 19) A solenoid valve as claimed in Claim 18, characterized in that said electromagnet (17) is energized by an electronic circuit according to a predetermined voltage (speed-up) pattern; said electronic circuit being located on an electronic board (76) fixed to said other half-shell (8) and connected electrically to said plugs (45) . 20) A method of producing a high-speed three-way solenoid valve for a fluid at other than ambient pressure, said solenoid valve (5) having a valve body (6) comprising two half-shells (7, 8) connected in fluidtight manner and enclosing a compartment (9) housing the armature of an electromagnet; a first of said half-shells (7, 8) having conduits (12-14) for said fluid; the other of said half-shells (7, 8) comprising a cavity (39) for housing said electromagnet (17), and a seat (68) for housing a bush (67) containing an elastic member (66) acting on said armature (24); the method being characterized by comprising the steps of: - injecting plastic material into a first mold to form said first half-shell (7) with said conduits (12- 14); - preparing said electromagnet (17) and said bush (67) with said elastic member (66); - placing said electromagnet (17) as an insert inside a second mold; - injecting plastic material into said second mold with said insert (17) to form said other half-shell (8) having said seat (68); - force-fitting said bush (67) with said elastic member (66) inside said seat (68); - placing said armature (24) inside said compartment (9), and inserting a seal (11) between said half-shells (7, 8 ) ; and - connecting said half-shells (7, 8) to each other by means of fast-fit connecting members. 21) A method as claimed in Claim 20, and also comprising the steps of: - fixing an electronic board (76) , for controlling said electromagnet (17), to said other half-shell (8); and - connecting said electronic board (76) electrically to said electromagnet (17) .