SELECTOR

Abstract: An electronic jacquard including a plurality of elongate heald hooks (1A, 1B) movable longitudinally between upper and lower shed positions and a plurality of electrically operable selection devices (50) for co-operation with the heald hooks (1A, 1B) for selectively retaining the heald hooks (1A, 1B) at one of said shed positions, each selection device including a latch (4A, 4B) movable between a latched position and a non-latched position, the latch (4A, 4B) when at said latched position being capable of latching engagement with the heald hook (1A, 1B) in order to retain it at said shed position, and an ultrasonic cyclic motor (55), preferably a piezo-electric motor, drivingly arranged to move the latch (4A, 4B) from its non-latched position to its latched position.

Description: SELECTOR The present invention relates to an electronic jacquard, in particular for controlling warp selection in a weaving loom. In conventional electromagnetic jacquards, see for example EP 0188074, the jacquard selectively controls raising and lowering of warp yarns between upper and lower shed positions. In EP 0188074 a pair of hooks are connected via a pulley to one or more harness cords which in turn is (are) connected to healds through which the warp yarns pass. The jacquard is provided with selection devices which selectively operate to capture one or other of a pair of hooks when that hook is at its uppermost position. This action, in co-operation with the pulley, results in the harness cord raising or retaining the heald and warp yarn at the top of the V shaped shed opening on the warp bed on the loom. Not to select/capture the hook results in the heald/warp lowering or remaining at the bottom of the V shaped shed opening. In other types of jacquard, a single hook is connected to the harness cord such that raising/lowering of the single hook directly results in raising/lowering of the heald. According to one aspect of the present invention there is provided an electronic jacquard including a plurality of elongate heald hooks movable longitudinally between upper and lower shed positions and a plurality of electrically operable selection devices for co-operation with the heald hooks for selectively retaining the heald hooks at one of said shed positions, each selection device including a latch movable between a latched position and a non-latched position, the latch when at said latched position being capable of latching engagement with the heald hook in order to retain it at said shed position, and an ultrasonic cyclic motor, preferably a piezo-electric motor, drivingly arranged to move the latch from its non-latched position to its latched position. Preferably the latch is biased to its non-latched position so as to be capable of moving from its latched position to its non-latched position under the influence of said bias. Preferably the latch is mounted on a support arm which is formed of a resilient material, preferably spring steel, the arm being fixedly mounted at one end to a body of the selection device and carrying said latch at its opposite end. Preferably the piezo-electric motor is arranged to move an actuator member which engages the support arm, preferably at a location intermediate the ends of the arm, in order to move the latch to its latched position. Preferably, the hooks are arranged in pairs for raising/lowering a harness pulley, and each selection device preferably includes a pair of latches and a single motor arranged to control movement of both latches to their respective latched positions. Preferably each latch is arranged to be rotated upon retaining engagement with a hook when at its latch position, biasing means being provided to resist said rotation. According to another aspect of the present invention there is provided an electronic jacquard including a plurality of elongate heald hooks movable longitudinally between upper and lower shed positions and a plurality of electrically operable selection devices for co-operation with the heald hooks for selectively retaining the heald hooks at one of said shed positions, each selection device including a latch movable between a latched position and a non-latched position, the latch when at said latched position being capable of latching engagement with the heald hook in order to retain it at said latch position, the latch when at said latched position being movable between a retention position and a release position, biasing means being provided to resiliently bias the latch to its release position, the hook and latch co-operating such that the hook on engagement with the latch causes the latch to move to its retention position against said resilient bias, and an electrically operable actuator for selectively moving the latch to its latched position. Preferably the actuator is an ultrasonic cyclic motor, preferably a piezoelectric motor. Reference is now made to the accompanying drawings, in which :- Figure 1 is a schematic side view of an embodiment according to the present invention illustrated in a first operational position; Figures 2 to 7a/b are similar views to Figure 1 showing the embodiment in different operational positions; Figure 8 is a front view of an upper portion of a heald hook shown in Figure 1 ; Figure 9 is a schematic diagram illustrating the principle of operation of an ultrasonic motor as used in the present invention. Referring initially to Figure 1, there is shown a selection device 50 arranged to control a pair of heald hooks la, lb which operate to raise and lower a harness pulley (not shown). The selection device 50 includes a body 9 made for example from plastics, having guide channels 3a, 3b for guiding longitudinal movement of the upper portion of the heald hooks la, lb respectively. The selection device 50 includes an electrically operable actuator 55 which is arranged to drive an actuator member 5 either to the left or right as required. Preferably the actuator 55 is an ultrasonic cyclic motor, preferably a piezo-electric motor having an elongate casing 11 from one end of which projects a drive output in the form of a drive finger 2. The actuator member is preferably in the form of a block or rod of a suitable material which is connected at opposite ends to arms 58a, 58b of a bracket 58. The arms 58a, 58b are movable to enable movement of the actuator member 5 to the left or right of casing 111. In addition the bracket is biased by biasing means preferably in the form of a spring 7, in order to maintain positive contact between the drive finger 2 and the actuator member 5. Referring initially to figure 9, there is shown an ultrasonic motor 110 including a casing 111 which houses a drive finger 12. The drive finger 12 is arranged to cyclically move along a cyclic path from a retracted position A (as shown) to an extended position B (shown in broken lines) and then whilst in its extended position, to the position C and then retracted to position D and then whilst in its retracted position, to position A. The finger 12 is driven at high speed through the cycle of positions A,B,C and D, preferably by piezo-electric elements (not shown) housed within the casing 111. The direction of movement through the cycle may be A to B to C to D or may be reversed, viz A to D to C to B depending upon the applied electrical current. By placing a member 14 to be driven in the path of the finger 12 whilst it moves between positions B to C (or vice versa), it is possible for the finger 12 to drive, in a stepwise manner, the member 14 is the same direction of travel. This type of motor operates at high speeds, typically at cycles of between 20 to 140 KHz. The motor typically has a cross-sectional dimension of about 8 mm x 4 mm and a length of about 25 mm. The selection device 50 also includes a pair of latches 4 which are each movable from a non-latched position (as seen in Figure 1) to a latched position (as seen by reference to the latch co-operating with heald hook la in Figure 2). Each latch 4 is mounted on one end of a resilient arm 10, the opposite end of arm 10 being fixedly mounted to the body 9. Accordingly the resilient arm 10 is arranged to act as biasing means for biasing each latch 4 to its non-latched position. Preferably each latch 4 is formed from a moulded plastics material. Preferably each arm 10 is formed from a spring strip material such as spring steel. The actuator member 5 is arranged to engage the arm 10 at a position intermediate the ends of the arm 10 and so enables a suspended latch 4 to be pushed through a hole 6 formed in the hook 1 (see Figures 1 and 8). Thus each selection device 50 when actuated acts to move latches 4a and 4b into the holes 6 in their respective hooks la and lb and thus capture the hook when required. The length of the hook 1 above the hole 6 is not important but the hole 6 must align with the latches 4 when the hook is raised to its uppermost position. In Figure 1 the motor 2 has moved the actuator member 5 to a central position where the latches 4 are not required to engage with the hole 6 in either hook 1. Hook la is shown at its uppermost position and hook lb is at its lowest position. Figure 2 shows a latch 4a at its latched position whereat it has been pushed through the hole 6 of hook la by actuator member 5 following the operation of motor 2 moving the actuator member 5 to the left. Since both latches 4a and 4b are biased towards the centre, ie. to their non-latched position, then latch 4b has been allowed to move towards the left moving further away from hook lb. Figure 3 illustrates an example of pre-selecting latching of a heald hook. As required by prior art EP 0188074 at some time later in the cycle from the selection point, the hook la has been captured by latch 4a at its uppermost position and hook lb has been raised by its lifting member up from the lowest position of hook travel. Since in this case it is necessary to retain the second hook lb at its upper position, the motor 2 has been actuated to move the actuator member 5 to the right. As illustrated in Figure 3, this has caused latch 4b to engage the upper portion of hook lb and has thus pre-loaded the latch 4b ready to engage hole 6 in hook lb when the hook is raised to the uppermost position (this is shown in Figure 4). It is not essential but preferable that this pre-load function is used in high speed jacquards. In accordance with the preferred embodiment of the invention, the latch 4a has been mechanically interlocked with hook la and no longer requires actuator member 5 to hold it at its latch position. For practical reasons there may be a neutral position wherein actuator member 5 is located central to body 9 and at this position neither latch 4a nor 4b is pushed by member 5; ie. both latches are at their non-latched position. However, this neutral condition is not essential. It will be appreciated that the member 5 does not require a neutral position between latches 4a and 4b for the selection device to operate correctly. For example to avoid retention of hook la, motor 2 is actuated to move member 5 to the right against latch 4b whether or not latch 4b is engaged in hook lb as the spring component of latch 4b takes up the travel of block 5 to the right. Figure 6 illustrates the mechanical load path. Starting with the downward force on the hook LI the load is transferred via the latch L2, arm L3, latch anchor L4, selector body L5, L6 and finally the interface contact between the selector body and the frame L7. Apart from friction contact between the spring arm L3 and the actuator member 5, the load path misses out the actuator 55 and member 5 thus avoiding any distortion of the actuator material or connecting wires. The actuator life is not effected by the selector loads allowing the selector body to be manufactured in a compact, flexible scale. In Figures 7a, 7b there is illustrated an example of achieving impact reduction. It is normal for jacquard hooks to be captured by stiff latches. This has the effect of suddenly stopping the harness while it is in motion causing an impact on the latch and the harness. Similarly, when the hook is lifted from the latch there is a sudden motion of the harness which results in a steep force change in the selector device and that member of the jacquard used to lift the hook. Both the forces produced when retaining the hook on the latch and the forces produced when the hook is lifted from the latch can be reduced by incorporating a resilient latch design. Figure 7a shows the position of latch 4a before the hook la has moved down onto the latch. This position is referred to as the release position. A short time later the hook la has moved down and the position of the latch 4a is changed to that shown in Figure 7b. This position is referred to as the retention position. The hook la has loaded the latch 4a which due to the shape of the recess 11 in the selector body 9 and the resilience of the spring arm 10 has allowed the latch 4a to rotate creating a torque reaction which reduces the deceleration of the hook and harness inertia and thus impact. Similarly when the hook is raised from the latch by its lifting member on the jacquard the situation changes from diagram 7b to that of 7a. During this time the hook lifting is assisted by the reaction force from latch 4a thus reducing the force on the hook lifting member and reducing the rate of change of force on the latch. By this means the resilient construction of the latch 4a and its recess 11 reduce the effects of capturing and releasing the hook la. It will be appreciated that the preferred embodiment of the invention enables operation of two movable latches for capturing either or both cooperating hooks at the top of their stroke utilising a single ultrasonic piezo motor driving an actuator member against the spring arm carrying the latches. The latches have a mechanical means of interlocking with the hook such that once engaged, the actuator member may be removed from the spring arm while the latch is carrying the downward load of the hook.

Claims: CLAIMS 1. An electronic jacquard including a plurality of elongate heald hooks movable longitudinally between upper and lower shed positions and a plurality of electrically operable selection devices for co-operation with the heald hooks for selectively retaining the heald hooks at one of said shed positions, each selection device including a latch movable between a latched position and a non-latched position, the latch when at said latched position being capable of latching engagement with the heald hook in order to retain it at said shed position, and an ultrasonic cyclic motor, preferably a piezo-electric motor, drivingly arranged to move the latch from its non-latched position to its latched position. 2. A jacquard according to Claim 1 wherein each motor includes a drive output comprising a drive finger which is driven cyclically along a cyclic path, the motor preferably operating at a frequency of between 20 to 140 kHz. 3. A jacquard according to Claim 1 or 2 wherein the latch is biased to its non-latched position so as to be capable of moving from its latched position to its non-latched position under the influence of said bias. 4. A jacquard according to Claim 3 wherein the latch is mounted on a support arm which is formed of a resilient material, preferably spring steel, the arm being fixedly mounted at one end to a body of the selection device and carrying said latch at its opposite end. 5. A jacquard according to Claim 4 wherein said motor is arranged to move an actuator member which engages the support arm, preferably at a location intermediate the ends of the arm, in order to move the latch to its latched position. 6. A jacquard according to any preceding claim wherein said hooks are arranged in pairs for raising/lowering a harness pulley, and each selection device preferably includes a pair of latches and a single motor arranged to control movement of both latches to their respective latched positions. 7. A jacquard according to any preceding claim wherein each latch is arranged to be rotated upon retaining engagement with a hook when at its latch position, biasing means being provided to resist said rotation.

Inventors: WARDLE MIKE, WARDLE, MIKE
Applicants: BONAS MACHINE CO, WARDLE MIKE, BONAS MACHINE COMPANY LIMITED, WARDLE, MIKE
Application year: 1999
Main classification: D03C3
IPC codes: D03C3