WO2003052184A1

WO2003052184A1 - Electromagnetic actuator usable for selecting movable members

Info

Publication number: WO2003052184A1
Application number: PCT/IT2002/000799
Authority: WO
Inventors: Gino Stevenin
Original assignee: Microlys S.P.A.
Priority date: 2001-12-18
Filing date: 2002-12-18
Publication date: 2003-06-26
Also published as: ITTO20011190A1; AU2002361500A1; ITTO20011190A0

Abstract

An electromagnetic actuator having a fastening base supporting an electromagnet having a pair of like-polarity pole pieces; a movable assembly having a selector member, an armature made of ferromagnetic material, and at least one permanent magnet contacting the armature; and supporting means for connecting the movable assembly to the fastening base, so that the armature is located loosely inside a seat defined between the pair of like-polarity pole pieces of the electromagnet; the supporting means allowing the movable assembly to move between two opposite operating positions, in which the armature is attracted to one of the like-polarity pole pieces.

Description

ELECTROMAGNETIC ACTUATOR USABLE FOR SELECTING MOVABLE MEMBERS

TECHNICAL FIELD

The present invention relates to an electromagnetic actuator which may be used to advantage as a highly reliable, compact selector on textile machines, particularly jacquard looms. BACKGROUND ART

As is known, the actuators used on textile machines, e.g. as selectors for operating movable members, such as cutters, spools, shuttles, etc., are normally pneumatic, on account of the highly dusty, flammable working environment involved. Pneumatic actuators, however, have the dual drawback of being extremely bulky and failing to provide for high-speed selection, both of which are further compounded on jacquard looms, which have hundreds of tightly packed movable members for selection. Electromagnetic actuators have therefore been proposed, and which have the advantage of higher selection speed. To eliminate sparks for fire-prevention reasons, however, known electromagnetic actuators are so- called "suction" types, in which the movable selector member is a pin which slides inside a seat in a substantially airtight body containing the electromagnet. This solution has the dual drawback of being relatively bulky and subject to frequent jamming caused by dust particles settling in the selector pin seat. DISCLOSURE OF INVENTION

It is an object of the present invention to eliminate all the aforementioned drawbacks by providing an actuator particularly suitable for selecting movable members on textile machines, and which at the same time provides for high selection speed, is compact and highly reliable, and is absolutely safe by being substantially sparkfree . According to the present invention, there is provided an electromagnetic actuator comprising a fastening base supporting an electromagnet; a movable assembly comprising a selector member; and supporting means for supporting said movable assembly; said supporting means allowing said movable assembly to move between two opposite operating positions; characterized in that said electromagnet comprises a pair of like- polarity pole pieces; said movable assembly comprising an armature made of ferromagnetic material, and at least one permanent magnet contacting said armature; the armature being located loosely inside a seat defined between said pair of like-polarity pole pieces of the electromagnet, so that, in said opposite operating positions, the armature is attracted selectively to one of said like- polarity pole pieces .

The supporting means comprise one or two elastically flexible arms fixed integrally, at one side, to said movable assembly, and, at the opposite side, to said fastening base, from which they project on the side facing said electromagnet, or to a fixed member of a textile machine to which the actuator according to the invention is fitted. In the first case, the arms have S-shaped bends to enable the formation, in use, of selector devices having pairs of actuators arranged with the fastening bases on opposite sides, and with the respective selector members arranged side by side, on opposite sides, and coaxial with each other for maximum compactness .

When the electromagnet is energized, the armature is attracted by one or other of the like-polarity pole pieces with sufficient force to flex the elastic arms, so that the movable assembly moves towards the pole piece attracting the armature, and the selector member is set to a first predetermined, e.g. engaged, operating position. When the voltage polarity is inverted, the polarity of the like-polarity pole pieces between which the armature is located is also inverted to move the selector member of the movable assembly into a second predetermined, e.g. release, operating position opposite to the first.

The engaged/release positions can thus be selected safely, by depending solely on the polarity of the applied voltage. Moreover, the structure described ensures a complete engaged/release stroke with a very small air gap, thus increasing selection speed. Finally, the structure according to the invention is immune to jamming caused by dust deposits, and produces no sparks.

A further advantage, as compared with known electromagnetic selectors, is the saving in energy made possible by the fact that, once the operating positions are attained, the electromagnet need not be kept energized to keep the actuator locked in position, the force of attraction exerted by the permanent magnet being sufficient to withstand the elastic reaction of the supporting means. BRIEF DESCRIPTION OF THE DRAWINGS

A number of non-limiting embodiments of the invention will be described by way of example with reference to the accompanying drawings, in which:

Figure 1 shows a partly sectioned side view of an electromagnetic actuator in accordance with the present invention;

Figure 2 shows a perpendicular front view of the Figure 1 actuator;

Figure 3 shows, schematically, one possible application on a textile machine of actuators as shown in Figures 1 and 2;

Figures 4 and 5 show, schematically, two variations of the actuator according to the invention, used in the same application as in Figure 3.

BEST MODE FOR CARRYING OUT THE INVENTION With reference to Figures 1, 2 and 3, number 1 indicates as a whole an electromagnetic actuator comprising a selector member 2; and supporting means 3, 4 for connecting a fastening base 5, supporting an electromagnet 6, to a movable assembly 8 comprising selector member 2.

Movable assembly 8 (Figures 1, 2) comprises an armature 10, for electromagnet 6, made of ferromagnetic material; and at least one permanent magnet 11 contacting armature 10. In the embodiment shown, movable assembly 8 comprises a body 12 supporting armature 10 at a first end 13 facing electromagnet 6, and defining a seat for housing selector member 2 at a second end 14 opposite the first. Inside end 13, body 12 also supports permanent magnet 11 inserted inside or glued to armature 10.

In the embodiment shown, body 12 is made of nonferromagnetic material, in which is embedded/inserted a pack of two elements made of ferromagnetic material and which form armature 10 and sandwich magnet 11. In a variation non shown for the sake of simplicity, armature 10 may be in the form of a laminated pack comprising a number of magnetic laminations in which magnet 11 is inserted/glued.

Selector member 2 can be made of any material of sufficient mechanical strength and hardness (even ferromagnetic, seeing as it is insulated from armature 10 by body 12) , whereas body 12 is preferably made of aluminium, light alloy, or synthetic plastic material, in which armature 10 of ferromagnetic material, with magnet 11 already inserted, and selector member 2 can be co- molded integrally into one piece.

Electromagnet 6 comprises a core 15 (Figure 1) defined by a pack of laminations 16, shown partly by the dash line, or in the form of a monolithic member. In both cases, the core is made of ferromagnetic material and E- shaped, so that electromagnet 6 as a whole comprises a pair of like-polarity pole pieces 18, 20 defined by a first (19) and an opposite second (21) lateral arm of the

E-shaped pack of laminations 16; while a central arm 22

(shown by the dash line in Figure 1) , located between lateral arms 19, 21, of the E-shaped pack of laminations 16 defines a third pole piece 23 of the electromagnet, of opposite polarity to that - of pole pieces 18, 20, and wound with a coil 24 of electromagnet 6.

According to the invention, central arm 22 is shorter than lateral arms 19, 21, which are symmetrical and of the same length, so as to define, between lateral arms 19, 21, a gap defining a seat 25 for housing armature 10 loosely between pole pieces 18, 20. According to the invention, selector member 2 is defined by a preferably cylindrical pin projecting from end 14 on the same side as and axially outwards of a first of like- polarity pole pieces 18, 20 of electromagnet 6 - in the example shown, pole piece 20. In combination with the above characteristics, supporting means 3, 4 according to the invention allow movable assembly 8 to move between two opposite operating positions as shown in Figure 3 and described in detail later on. For which purpose, the supporting means according to the invention comprise two elastically flexible arms 3, 4 fixed integrally at a first end 3a, 4a to fastening base 5, from which they project on the side facing electromagnet 6, and at a fork-shaped second end 3b, 4b to movable assembly 8.

Like-polarity pole pieces 18, 20 of electromagnet 6 are located between elastically flexible arms 3 , 4 with a clearance substantially equal to or greater than that of armature 10 inside seat 25 defined between pole pieces 18, 20.

When electromagnet 6 is deenergized, actuator 1 would therefore theoretically be in the rest configuration shown in Figure 1, in which flexible arms 3, 4 are undeformed, and armature 10 is substantially equidistant from pole pieces 18, 20. In actual fact, however, even when the electromagnet is deenergized, actuator 1 is always in one or other of the two limit operating positions, owing to the attraction exerted anyway by magnet 11. Figure 3 shows, schematically, a selector device 100 for known movable members 101 of a known textile machine 102, e.g. a jacquard loom, employing a number of pairs (only one shown) of electromagnetic actuators 1 indicated la and lb.

In actual use (Figure 3) , depending on the polarity applied to electromagnet 6, armature 10 of each actuator 1 is selectively attracted by pole piece or pole 20 (and simultaneously repulsed by pole piece or pole 18 actuator lb at the bottom in Figure 3) , or is selectively attracted by pole 18 and repulsed by pole 20 (actuator la at the top in Figure 3) , so that sufficient force is exerted on movable assembly 8 to flex arms 3, 4 in the appropriate direction and so move movable assembly 8, and respective selector member 2, between two opposite operating positions as shown in Figure 3 : a first of actuator la and a second of actuator lb, in which the armature is selectively attracted to and substantially rests against one of the like-polarity pole pieces of electromagnet 6 (18 and 20 respectively) .

Tests have shown that, once the above position is attained, there is no need to keep the electromagnet energized, in that the force of attraction exerted by the permanent magnet of the movable assembly is sufficient to withstand the elastic reaction of the supporting means and so keep the actuator locked in position.

To fix actuators 1 easily, fastening base 5 of each at least partly houses respective electromagnet 6, and may be provided with a number of (in the example shown, three) perpendicular through holes 50 for known fastening members (e.g. bolts or rivets, not shown) by which to fasten actuator 1 to a user machine - in the example shown, textile machine 102. Base 5 is preferably made of synthetic plastic resin, into which electromagnet 6 is co-molded integrally in one piece.

Elastically flexible arms 3 , 4 of each actuator 1 according to the invention are defined by spring steel plates or formed in one piece with base 5, also of synthetic plastic material of suitable elastic characteristics; are carried parallel to each other by fastening base 5; and have respective S-shaped bends 30, 40 at ends 3b, 4b, so that ends 3b, 4b are closer together than the corresponding opposite ends 3a, 4a. Moreover, with the exception of respective projecting selector member 2, movable assembly 8 of each actuator 1 is located entirely between the closer ends 3b, 4b of arms 3 , 4.

Each pair of electromagnetic actuators la, lb of device 100 in Figure 3 may therefore be located in the gap between a pair of members 103 fixed to textile machine 102. Members 103 are defined, for example, by respective structural supporting members of the jacquard loom, or form part of a "body" member supporting each pair of electromagnetic actuators la, lb, and by which electromagnetic actuators la, lb are fixed integrally to the textile machine (jacquard loom) . In either case, according to the invention, actuators la, lb are mounted with respective fastening bases 5 on opposite sides and fixed integrally to members 103, so that respective selector members 2 are positioned coaxially side by side, and engage, on opposite sides, respective through holes 104 in members 103. On the other side of holes 104, are located the movable members (loom cutters) 101 for selection, each of which has a seat 105 engageable by the free end of the corresponding selector member (cylindrical pin) 2.

In the first operating position (actuator la) , pin 2 is detached from seat 105, so that the respective cutter 101 is movable freely; whereas, in the second operating position (actuator lb) , pin 2 engages seat 105 to lock respective cutter 101.

Figures 4 and 5, in which any details similar to or identical with those already described are indicated using the same reference numbers, show possible variations of actuators la, lb according to the invention, and which differ from actuators la, lb by the supporting means of movable assembly 8 of each actuator being defined by one or two elastically deformable arms 110 preferably made of spring steel and fixed, at one end, to a respective movable assembly 8, and, at the opposite end, to a fixed member 103 integral with textile machine 102, e.g. by means of a screw 111 (Figure 4) . More specifically, each arm 110 is connected to and projects from a fixed member 103 of textile machine 102 also supporting the corresponding fastening base 5 of the actuator, and is located on the opposite side to and projects towards fastening base 5.

Respective fastening bases 5 may be located on opposite sides (Figure 4) , as in the Figure 3 example, or side by side (Figure 5) , by virtue of the compactness of the solution with arms 110 separate from bases 5. Whichever the case, pins 2 are always mounted on opposite sides and coaxially side by side.

Finally, arms 110 may also be replaced (Figure 5) by supporting means defined by slideway means 120 (shown by the dash line) formed on bases 5 and engaged by respective known pads (not shown) carried integrally by movable assemblies 8.

Claims

1) An electromagnetic actuator (1) for a textile machine, comprising a fastening base (5) supporting an electromagnet (6) ; a movable assembly (8) comprising a selector member (2); and supporting means (3, 4) for supporting the movable assembly; said supporting means allowing said movable assembly to move between two opposite operating positions; characterized in that said electromagnet (6) comprises a pair of like-polarity pole pieces (18, 20) ; said movable assembly comprising an armature (10) made of ferromagnetic material, and at least one permanent magnet (11) contacting said armature; the armature being located loosely inside a seat (25) defined between said pair of like-polarity pole pieces of the electromagnet, so that, in said opposite operating positions, the armature (10) is attracted selectively to one of said like-polarity pole pieces (18, 20) .

2) An electromagnetic actuator as claimed in Claim 1, characterized in that said electromagnet (6) comprises an E-shaped core (15) made of ferromagnetic material (16) ; said like-polarity pole pieces being defined by a first and an opposite second lateral arm (19, 21) of the E-shaped core, while a central- arm (22), located between said lateral arms, of the E-shaped core defines a third pole piece of the electromagnet, of opposite polarity to that of said pair of like-polarity pole pieces, and is wound with a coil (24) of said electromagnet; said central arm (22) being shorter than said first and said second lateral arm (19, 21) , so as to define, between the first and second lateral arm, a gap defining said seat (25) for the armature (10) . 3) An electromagnetic actuator as claimed in Claim 1 or 2, characterized in that said movable assembly (8) comprises a body (12) supporting said armature (10) at a first end (13) facing said electromagnet; said first end supporting said permanent magnet (11) inserted in or glued to said armature; and said body (12) supporting, at a second end (14) opposite the first, a seat for housing said selector member (2) .

4) An electromagnetic actuator as claimed in Claim 3, characterized in that said selector member is defined by a pin (2) projecting from said seat defined by said second end (14) of said body of the movable assembly, and on the same side as and axially outwards of a first (20) of said like-polarity pole pieces of the electromagnet.

5) An electromagnetic actuator as claimed in any one of the foregoing Claims, characterized in that said fastening base (5) at least partly houses said electromagnet .

6) An electromagnetic actuator as claimed in Claim 5, characterized in that said fastening base (5) has a number of perpendicular through holes (50) for fastening members by which to fasten the actuator to a user machine .

7) An electromagnetic actuator as claimed in any one of the foregoing Claims, characterized in that said supporting means comprise a pair of elastically flexible arms (3, 4) fixed integrally, at a first end (3a, 4a), to said fastening base, from which they project on the side facing said electromagnet, and, at a second end (3b, 4b) , to said movable assembly; said electromagnet (6) being located between said elastically flexible arms (3, 4) with a clearance substantially equal to or greater than that of said armature (10) inside the seat (25) defined between said like-polarity pole pieces.

8) An electromagnetic actuator as claimed in Claim

7, characterized in that said elastically flexible arms (3, 4) are carried parallel to each other by said fastening base, and have respective S-shaped bends (30, 40) at said second ends (3b, 4b) , so that said second ends of said elastically flexible arms are closer together than the corresponding first ends (3a, 4a) .

9) An electromagnetic actuator as claimed in Claim

8, characterized in that, with the exception of said selector member (2) , said movable assembly (8) is located entirely between said second ends (3b, 4b) of the elastically flexible arms.

10) A selector device (100) for textile machines (102) , comprising at least one pair of electromagnetic actuators (la, lb) as claimed in one of Claims 1 to 6; said pair of electromagnetic actuators being located in the gap between a pair of members (103) fixed to the textile machine, with the respective said fastening bases (5) fitted integrally to said members fixed to the textile machine, so that the respective selector members (2) of said pair of electromagnetic actuators are located coaxially side by side, and engage, on opposite sides, respective holes (104) formed through said members fixed to the textile machine and on the other side of which are located respective movable members (101) of the textile machine to be selected by engagement/release by the selector members of the actuators . 11) A device as claimed in Claim 10, characterized in that said supporting means comprise, for each said fastening base (5) , at least one elastically flexible arm

(110) which is connected to and projects from a said member (103) fixed to the textile machine supporting the corresponding said fastening base (5) , and is located on the opposite side to and projects towards the fastening base.

12) A device as claimed in Claim 10 or 11, characterized in that the respective said fastening bases (5) are located on opposite sides.

13) A device as claimed in Claim 10 or 11, characterized in that the respective said fastening bases (5) are located side by side.

14) A textile machine (102) , in particular a jacquard loom, employing a number of selector devices as claimed in one of Claims 10 to 13.