EP1541728A1

EP1541728A1 - Method of controlling electric opening device

Info

Publication number: EP1541728A1
Application number: EP03792834A
Authority: EP
Inventors: Jun Hirai
Original assignee: Tsudakoma Industrial Co Ltd
Current assignee: Tsudakoma Corp
Priority date: 2002-08-26
Filing date: 2003-08-25
Publication date: 2005-06-15
Also published as: CN1675420A; JPWO2004018752A1; WO2004018752A1; EP1541728A4

Abstract

A control technique of an electric shedding device is characterized by setting conditions of one or more weaving elements, obtaining a torque restriction value of each electric motor (38) according to the set weaving conditions, and setting the obtained torque restriction value for each electric motor (38). This enables to avoid shortening of the life due to damage to driving parts of heald frames (36) or the electric motor (38) and to improve weaving property.

Description

Field of the Invention

The present invention relates to a method of controlling an electric shedding device having an electric motor for each heald frame.

Background Art

As an electric shedding device is known a technique in which a position control loop of an electric motor, a speed control loop or a loop gain of a current control loop are set according to a shedding pattern, to avoid inability to weave because of a delay in responding of the heald frame due to a too small loop gain relative to the shedding pattern (Japanese Patent Appln. Public Disclosure (KOKAI) No. 11-241250).

In the above-mentioned prior art, however, while the loop gain is changed according to the shedding pattern, the maximum torque of the electric motor cannot be appropriately controlled. Therefore, depending on a setting condition of the loop gain, acceleration or deceleration of the heald frame exceeds an allowed value, thereby causing shortening of life due to damage to or wear and the like of driving parts of the heald frame or the electric motor. Consequently, the rotational speed of a loom should be lowered.

DISCLOSURE OF THE PATENT

An object of the present invention is to avoid shortening of life due to damage to or wear and the like of driving parts of a heald frame or an electric motor and to raise weaving property.

Control methods according to the present invention are all applicable to controlling of an electric shedding device of a type in which a plurality of heald frames are respectively driven by an exclusive electric motor and in which an output torque of the electric motor is restricted according to a predetermined torque restriction value.

A first control method according to the present invention comprises obtaining of a torque restriction value of the electric motor according to a setting mode at least one weaving element and setting the obtained torque restriction value as the torque restriction value of the electric motor.

In the first control method, a plurality of torque restriction values are preliminarily set according to the setting mode of the weaving elements, and in obtaining the torque restriction value of the electric motor, the torque restriction value according to the setting mode of the weaving elements can be selected. Also, preferably, a plurality of factors for computing the torque restriction value corresponding to the setting mode of the weaving elements are set for each weaving element, and in obtaining the torque restriction value of the electric motor, a factor corresponding to the setting mode of the weaving element can be selected for each weaving element, and the torque restriction value is obtained by operation from the selected factors and can be set as the torque restriction value of the electric motor.

A second control method according to the present invention comprises setting of the torque restriction value of each electric motor according to the heald frame No.

A third control method according to the present invention comprises obtaining and setting of the torque restriction value of the electric motor according to a setting mode of at least one weaving element and the heald frame No. More preferably, a factor relative to the torque restriction value is preliminarily factorized in correspondence to the setting mode of the waving element and the heald frame No., and the torque restriction value of the electric motor can be obtained and set by operation from the selected factor in correspondence to the setting mode of the weaving element and the heald frame No.

A fourth control method according to the present invention comprises enabling to be changed over at least one setting mode among the weaving elements during weaving operation, and obtaining and setting of the torque restriction value of the electric motor in correspondence to a changeover of the setting mode of the weaving element.

More preferably, in the fourth control method, in which a plurality of the foregoing torque restriction values are set in correspondence to a changeover of the setting modes of the weaving elements, and in changing over of the setting mode during the weaving operation, a torque restriction value corresponding to the changeover of the setting mode is selected and set as the torque restriction value of the electric motor.

In the fourth control method, the weaving elements can include at least one selected from a group including continuity of shedding motion from preceding several picks up to the changeover, composing elements of a shedding curve, direction of the shedding motion from the changeover, external force acting on the heald frame and the rotational speed of a loom.

In all of the foregoing second, third and fourth control methods, it can be included that: respective setting modes of plural weaving elements under weaving operation can be changed over, that plural torque restriction value factors corresponding to each setting mode are set in each weaving element, that a torque restriction value corresponding to the changeover of the setting mode is selected for each weaving element, and that, at the time of the changeover of the setting modes under weaving operation, the torque restriction value obtained by operation from the plural selected factors is set.

A fifth control method according to the present invention comprises: preliminarily setting of an output torque restriction value of the electric motor in correspondence to a first process where a rotational angle speed of a main shaft is accelerated or decelerated and to a second process where the rotational angle speed of the main shaft is maintained; and, in the first and second processes at the time of driving the shedding device, driving of the electric motor by restricting the output torque of a drive motor on the basis of output torque restriction values corresponding to those processes.

The foregoing exclusive electric motor is provided in the shedding device independently of a drive motor for the main shaft of the loom. Such an electric motor can be driven according to a predetermined shedding curve and following the rotation of the main shaft.

The above-mentioned torque restriction value may be either one of the maximum torque value and the maximum current value, because the torque value and the current correspond. In case of an instantaneous operation, an instantaneous maximum torque or an instantaneous maximum current can be used.

As weaving elements, shedding pattern, dwell angle, rotational speed of a loom, shedding amount, cloth width, warp tension, the number of warps, etc., can be enumerated.

According to the present invention, since the torque restriction value of the exclusive electric motor can be set at an optimum value in correspondence to the set weaving condition, the frame No. of the heald frame or the set torque restriction value, there will be caused neither damage to the driving parts or the electric motor due to an excessive torque nor failure in weaving attributable to a delay in responding of the heald frame because of a too small torque. That is to say, the optimum weaving property can be obtained without causing any damage to the driving parts or the electric motor due to an excessive torque or a delay in responding of the heald frame because of a too small torque.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a block diagram of an electric circuit showing one embodiment of the control device according to the present invention.

Figs. 2 (A) and (B) are graphs showing an example of the shedding pattern (A) according to the device in Fig. 1 and the driving torque of a servo motor.

Figs. 3 (A) and (B) are graphs showing an example of the shedding pattern (A) according to the device in Fig. 1 and the driving torque of a servo motor.

Fig. 4 is a general constitutional view of the shedding device showing another embodiment of the control device according to the present invention.

Fig. 5 is a block diagram showing details of a position command portion in the shedding control device shown in Fig. 4.

Fig. 6 is a table showing examples of setting of the shedding curves.

Fig. 7 is a block diagram showing details of the position control portion shown in Fig. 4.

Fig. 8 is a block diagram showing details of the current control circuit shown in Fig. 7.

Fig. 9 is a graph showing a timing chart of the current control circuit shown in Fig. 7.

Fig. 10 is a graph showing a timing chart following the timing chart shown in Fig. 9.

Fig. 11 is a flowchart for explaining a motion of the shedding selection command circuit shown in Fig. 5.

Fig. 12 is a flowchart following the flowchart shown in Fig. 11.

Fig. 13 is a flowchart following the flowchart shown in Fig. 12.

Fig. 14 is a flowchart following the flowchart shown in Fig. 13.

BEST MODE FOR WORKING THE INVENTION First Embodiment

Referring to Fig. 1, a control device 10 of an electric shedding device comprises: a main control device 12 of a loom, a setter 14 connected to the main control device 12; a shedding control device 18 for computing a torque restriction level, namely, a torque restriction value S2 for each heald frame 16 upon receipt of various set conditions S1 set in the setter 14; a servo amplifier 20 provided in each heald frame 16; a servo motor 22 provided in each heald frame 16; and an encoder 24 for outputting a rotational angle signal 1 representing the rotational angle of each servo motor 22 to the shedding control device 18.

Fig. 1 only shows one heald frame 16, the servo amplifier 20 corresponding to the heald frame 16, the servo motor 22 as an electric motor for driving the heald frame 16, and the encoder 24 for generating the rotational angle 1 of the servo motor 22. Actually, however, a plurality of heald frames 16 are provided, and the servo amplifier 20, servo motor 22 and encoder 24 are provided in each heald frame 16.

In other words, a plurality of servo amplifiers 20 are connected to one shedding control device 18 in correspondence to the number of the frames of the heald frame 16. And what is called electric motor in the present invention corresponds to the servo motor 22, the drive unit to the servo amplifier 20, and the control circuit to the main control device 12 and the shedding control device 18, respectively. Also, between the output shaft of the servo motor 22 and the heald frame 16, a publicly known reciprocal motion converting mechanism constituted by a bell crank and the like to convert the rotational motion of the output shaft into a reciprocal motion is interposed.

The main control device 12, like a general main control device used for a loom, controls various machinery of a loom such as the shedding device, a picking device, a weft length measuring storage unit, a warp tension adjusting device, a cloth take-up device and the like.

In the setter 14, in order to determine a motion curve of the heald frame 16 to be preset in correspondence to the rotational angle of the main shaft of the loom, parameters of a warp shedding motion such as a shedding pattern to be determined as either an upper shed shedding or an under shed shedding for each pick of weft insertion, a dwell angle, the amount of the warp shedding for setting a shedding motion mode are set for each heald frame 16, and setting data of weaving elements such as a rotational speed of the loom, a shedding amount, a cloth width, warp tension, the number of warps are set. These weaving elements as mentioned above relate to a load of the servo motor 22 which drives the heald frame, and to be used, in the main control device 12, for reading a plurality of factors which the heald frame 16 and various weaving elements are factorized for each heald frame. The read factors are supplied to the shedding control device 18 for each heald frame as set conditions S1.

Those factors are factorized by a test, calculation and the like, for example, so that the weaving property and the durability of the driving parts are the most balanced, and are preset in the main control device 12. The main control device 12 reads a plurality of corresponding factors, based on a setting function (setting data) of plural weaving elements set in the setter 14, and outputs the read factors to the shedding control device 18 as set conditions S1.

The setter 14 preliminarily prepares a shedding curve corresponding to the main shaft rotational angle for each heald frame, on the basis of parameters such as a parameter of shedding motion as mentioned above and a cross timing of the shedding device, and feeds it to the shedding control device 18 via the main control device 12. The shedding curve as fed is stored in the shedding control device 18.

For this reason, the shedding control device 18 outputs a drive amount signal (not shown) corresponding to an inputted main shaft rotational angle signal 0 to each of

servo amplifiers

20, 20, ... for driving the heald frame. On the other hand, the rotational angle signal 1 from the encoder 24 corresponding to the

servo motors

22, 22, ..., is inputted to each of the

servo amplifiers

20, 20, ...

Each of the

servo amplifiers

20, 20, ... , while following the drive amount signal corresponding to the rotational angle of the main shaft to be inputted from the shedding control device 18, can drive

respective frames

16, 16, ..., by controlling a torque (current) in correspondence to a torque restriction signal S2 to be determined by a factor corresponding to a weaving element to be inputted likewise as mentioned later, i.e., by restricting an output current to the restriction value and by supplying it to the

respective servo motors

22, 22, ...

Also, a loom control signal (not shown) such as for loom operation, stopping, or the like has been inputted to the shedding control device 18 from the main control device 12, and the shedding control device 18 can also drive each heald frame by outputting a drive amount signal and a torque control value in correspondence to an input.

Factorization can be performed as described in Table 1 below. It is, however, possible to take into account either shortening of life due to damage to and wear or the like of driving parts and the electric motor or weaving property, and therefore, the factors in Table 1 are sometimes reversed in magnitude.

Here, the frame Nos. mean numbers given to a plurality of heald frames provided in parallel on the loom, and are, for example, given so as to increase from the nearest one to the cloth fell toward the farthest one. For example, in Table 1, the larger the momentum of the heald frames with larger numbers are, the factors are set smaller, while it is possible to set the factors the larger, the larger the momentum of the heald frames with larger numbers are, so as to make the delay in responding small at the time of acceleration and deceleration of the heald frames with large frame numbers, thereby improving the weaving property.

Intermittent shedding patterns (1/2 • 2/1, 1/3 • 3/1, etc.) tend to cause a delay in following at the time of acceleration and deceleration, and is unable to gain any sufficient shedding amount. Consequently, in case of such a shedding pattern, the factor value is increased to make the acceleration force and the braking force at the time of acceleration and deceleration. In more intermittent shedding patterns (1/4 • 4/1, 1/5 • 5/1, etc.) with a long stopping time, the stopping time of the heald frame is long, so that the servo motor 22 is not burned even if the factor is increased and the current value at the time of acceleration and deceleration is increased.

In the shedding pattern (1/1) of an ordinary shedding, the heald frame moves continuously, so that the braking force at the time of acceleration and deceleration can be small. Consequently, the factor value is controlled to be small to make the consumption power for the continuous motion not to increase. In other words, by the amount of the decrease in consumption power due to the reduced factor value, the servo motor 22 is not burned even if the rotational speed of the loom is raised.

Since in case of the heald frames with larger frame Nos. (the heald frames placed rearward in the moving direction of the warp, namely, the heald frames nearer the upstream side) the warp shedding amounts are set the larger, the momentum per rotation of the main shaft becomes great. Therefore, the greater the frame No. is, the smaller the factor value is made to prevent the driving parts from being damaged.

The wider the cloth width is, the greater the heald frames become, thereby increasing the kinetic energy at the time of acceleration and deceleration, so that, the greater the cloth width is, the smaller the factor value is made to prevent damage to the driving parts.

The greater the dwell angle is, the shorter the moving time of the heald frame becomes, thereby increasing the degrees of acceleration and deceleration. Therefore, the greater the dwell angle is, the smaller the factor value is made to prevent damage to the driving parts.

The greater the rotational speed of the loom is, the greater the degrees of acceleration and deceleration become, so that, the greater the rotational speed is, the smaller the factor value is are made to prevent damage to the driving parts.

The composing elements of the shedding motion such as the shedding pattern, frame No., cloth width and factorization of the rotational speed of the loom are summarized in Table 1, and an example of concrete factor values is shown in Table 2.

The shedding control device 18 temporarily stores the set condition S1 to be supplied from the main control device 12 and the final frame No. S3 (i.e., corresponding to the number of the heald frames to be mounted) of the heald frames 16 to be supplied from an external device in an internal memory, and, based on the stored set condition S1 and the final frame No. S3, calculates the torque restriction value for each heald frame.

Calculation of the torque restriction value is carried out by taking out the factor values from the set condition S1 and the first frame No. 1 to the last frame No. S3 from the setter 14 for each heald frame, and multiplying the factor values by the instantaneous maximum torque (or the instantaneous maximum current) of the electric motor corresponding to each heald frame, and obtaining the torque restriction value for each heald frame.

Table 2 shows an example of the factor values when the instantaneous maximum torque is made 200 % of the rating torque of the servo motor 22. In this case, the torque restriction value can be obtained from the following formula: Torque restriction value = rating torque × 200 % × each factor

The calculated torque restriction value is stored in the internal memory of the shedding control device 18 for each heald frame.

The shedding control device 18 supplies the stored torque restriction value S2 to the corresponding servo amplifier 20.

Each servo amplifier 20, based on a drive signal (not shown) and the torque restriction value S2 to be supplied from the shedding control device 18, drives the corresponding servo motor 22 while controlling the position of the corresponding servo motor 22 so that the torque or the current value may not exceed the restriction value. Each servo amplifier 20 controls the corresponding servo motor 22 so as to drive not to exceed the restriction value corresponding to the torque or the current value.

The following Figs. 2 and 3 show an actual position (shedding curve) of the heald frame and the driving torque value at that time, taking a shedding device as an example, wherein the servo motor is driven continuously in one direction when the heald frame descends from the upper shed shedding position and ascends again to return to its initial position.

Fig. 2 shows an example of the shedding pattern 1/1 for the heald frame of the frame No. 12 at the time of an ordinary shedding (plain weave) in (A), and the driving torque of the servo motor 22 at that time in (B). In both Figs. 2 (A) and (B), the abscissa shows the rotational angle (time) of the main shaft. The 0° on the abscissa in Fig. 2 (A) shows a timing for beating, and the rotational angle 0° at this time is 0°.

In Fig. 2 (A), the factor and torque restriction value are as follows:

Shedding pattern (1/1) = 0.6

Frame No. (12th frame) = 0.9

Cloth width (190 cm) = 1.0

Dwell angle (none) = 1.0

Rotational speed (900 rpm) = 0.8 Torque restriction value = rating torque × 200 % ×0.6 × 0.9 × 1 × 1 × 0.8 = rating torque × 86.4 %

In Fig. 2 (B), each flat region on the upside shows the acceleration time, and each flat region on the underside shows the deceleration time.

Fig. 3 shows an example of the shedding pattern 1/3 for the frame No. 1 heald frame in (A), and the driving torque of the servo motor 22 at that time in (B). In both Figs. 3 (A) and (B), the abscissa shows the rotational angle (time) of the main shaft. The 0° on the abscissa in Fig. 3 (A) shows the beating timing, and the rotational angle of the main shaft at this time is 0°.

In Fig. 3 (A), the factor and torque restriction value are as follows:

Shedding pattern (1/3) = 0.8

Frame No. (first frame) = 1.0

Cloth width (190 cm) = 1.0

Dwell (none) = 1.0

Rotational speed (550 rpm) = 0.95 Torque restriction value = rating torque × 200 % × 0.8 × 1 × 1 × 1 × 0.95 = rating torque × 152 %

In Fig. 3 (B), too, each of the upside flat regions shows the acceleration time, and each of the underside regions the deceleration time.

Table 2 does not show an example of a case of operating the torque restriction value by factorizing according to the setting mode of the weaving element. But Tables 3 and 4 show an example of a case of preliminarily setting the torque restriction value of the heald frame No. (frame No.). Table 3 shows an example of a case of presetting the torque restriction value of the ordinary shedding pattern 1/1 for each heald frame. Table 4 shows an example of a case of presetting the torque restriction value of each heald frame for each shedding pattern.

Factor	Small	Large
Shedding pattern	Continuous motion	Intermittent motion
Frame No.	Rear frame (large shedding amount)	Front frame (cloth fell side, small shedding amount)
Cloth width	Large	Small
Dwell angle	Large	Small
Rotational speed	High speed	Low speed

Embodiment

1
Torque restriction value = 200 % × factor × rating torque
Shedding pattern
	1/1	1/2 · 2/1	1/3 · 3/1	2/2	1/4 · 4/1
Factor	0.6	0.7	0.8	0.9	1.0
Frame No.	1 ~ 4	5 ~ 8	9 ~ 12	13 ~ 16
Factor	1.0	0.95	0.9	0.85
Width	~ 190 cm	210 ~ 230	250 ~ 290	330 ~
Factor	1.0	0.95	0.9	0.85
Dwell	0°~ 15°	16°~ 30°	31°~ 60°	61°~ 120°
Factor	1.0	0.95	0.9	0.85
Rotational speed	~ 500 r.p.m	501 ~ 600	601 ~ 700	701 ~ 800	801 ~ 900
Factor	1.0	0.95	0.9	0.85	0.8

Embodiment 2
Frame No.	1 ~ 4	5 ~ 8	9 ~ 12	13 ~ 16
Torque restriction value	170 % × rating torque	160 % × rating torque	150 % × rating torque	140 % × rating torque

Embodiment

3
Frame No.	1 ~ 4	1 ~ 4	1 ~ 4	1 ~ 4	1 ~ 4
Shedding pattern	1/1	1/2 · 2/1	1/3 · 3/1	2/2	1/4 · 4/1
Torque restriction value	120 % × rating torque	140 % × rating torque	160 % × rating torque	180 % × rating torque	200 % × rating torque
Frame No.	5 ~ 8	5 ~ 8	5 ~ 8	5 ~ 8	5 ~ 8
Shedding pattern	1/1	1/2 · 2/1	1/3 · 3/1	2/2	1/4 · 4/1
Torque restriction value	114 % × rating torque	133 % × rating torque	152 % × rating torque	171 % × rating torque	190 % × rating torque
Frame No.	9 ~ 12	9 ~ 12	9 ~ 12	9 ~ 12	9 ~ 12
Shedding pattern	1/1	1/2 · 2/1	1/3 · 3/1	2/2	1/4 · 4/1
Torque restriction value	108 % × rating torque	126 % × rating torque	144 % × rating torque	162 % × rating torque	180 % × rating torque
Frame No.	13 ~ 16	13 ~ 16	13 ~ 16	13 ~ 16	13 ~ 16
Shedding pattern	1/1	1/2 · 2/1	1/3 · 3/1	2/2	1/4 · 4/1
Torque restriction value	102 % × rating torque	119 % × rating torque	136 % × rating torque	153 % × rating torque	170 % × rating torque

In obtaining the torque restriction value in the foregoing embodiments, making the above-listed ones all the weaving elements, the torque restriction value is calculated according to the operation (multiplication) result of each factor value, but to simplify more, it suffices to calculate in correspondence to one or more conditions which are of comparatively great influence among those listed above. It may be as all the heald frames with the heald frame which is obtained the torque restriction value as above, and may be only as some heald frames.

Second Embodiment

The electric shedding device shown in the following is an example constituted to be capable of switching the torque restriction value during loom operation in contrast to the first embodiment. To add further, a shedding control device capable of further saving a memory capacity of data concerning driving a shedding curve and the like even for a fabric of a complicated structure is concretely shown.

Referring to Fig. 4, the control device 30 of the electric shedding device controls the rotational angle of a crank 44 connected to an electric motor 38, by controlling the rotational angle (rotational amount) of the electric motor 38 which is in one-to-one correspondence to each of plural heald frames 36, on the basis of the rotational angle signal 0 of the main shaft 32 which is outputted by an angle detector 34 such as an encoder for detecting the rotational angle of the main shaft 32 of the loom. In this embodiment, the number of the heald frames 36 is, for example, eight.

The control device 30 is provided with: a position command portion 40 individually commanding vertical positions of the first to eighth heald frames 36, 36, ..., after the rotational angle signal 0 of the main shaft 32 is inputted; and first to eighth

position control portions

42, 42, ..., where first to eighth position control signals Sp1, Sp2, ..., Sp8 outputted from the position command portion 40 are to be inputted.

The position control portions 42 are in one-to-one correspondence to the electric motors 38 as shedding motors. The electric motors 38 are in one-to-one correspondence to the heald frames 36. As each electric motor 38, the same servo motor as in the first embodiment can be used.

The rotation of each electric motor 38 is controlled by the drive power from the corresponding position control portion 42. The electric motor 38 rotates, by the torque of its output shaft, the crank 44 for shedding motion and vertically moves the corresponding heald frame 36 through a connection rod 46.

The heald frame 36 to be vertically moved has a plurality of warps 50 to make shedding motion through a plurality of healds 48 attached to the heald frame 36. Accordingly, since the crank 44, the connection rod 46 and the heald frame 36 have considerable masses, when making them perform rotational motion and vertical motion from stoppage, and when stopping their moving state, great inertia force acts on the electric motor 38.

Referring to Fig. 5, the position command portion 40 is explained in the following.

The position command portion 40 outputs: the first to eighth position control signals Sp1, Sp2, ..., Sp8 for controlling for each motor the rotation of the first to eighth electric motors 38 on the basis of shedding patterns to be described later in a state of being synchronized with the rotation of the main shaft 32 of the loom; and first to eighth torque restriction values S21, S22, ..., S28 which restrict the torque of the electric motors 38 for each motor.

The position command portion 40 has, therefore, a drive amount output circuit 52 for outputting a position control signal Spn, a torque restriction value generation circuit 54 for outputting a torque restriction value S2n, and a shedding selection command circuit 56 for outputting a selection command signal Sk which indicates a shedding curve. However, n = 1, ..., m, wherein m is the number of the heald frames to be calculated.

The shedding selection command circuit 56 has a stepping signal generator 58 which outputs selectively a forward stepping signal F and a backward stepping signal R according to the rotational direction of the main shaft 32 when the main shaft 32 normally rotated or reversed and passed a predetermined angle based on the rotational angle signal 0 of the main shaft 32; a shedding command setter 60 storing a shedding pattern for one round of rotation of the main shaft corresponding to each heald frame 36; and a selection controller 62 for selecting the No. of the shedding curve for vertically moving each heald frame 36 by using the forward stepping signal F and backward stepping signal R as well as the shedding patterns set for each heald frame 36.

The shedding pattern is a pattern representing ascension and descent of the heald frame 36 and is used for indicating the direction of the shedding motion of the heald frame 36. The shedding curve is a curve representing a position of the heald frame 36 in the vertical direction at the time of vertical motion and is to be used for commanding the speed of the shedding motion of the heald frame 36.

The stepping signal generator 58 generates a pulse-like forward stepping signal F when the main shaft 32 is normally rotating and the rotational angle signal 0 of the main shaft 32 becomes 110°, meaning that the main shaft 32 normally rotated and passed 110°, and when the main shaft 32 reverses and the rotational angle signal 0 of the main shaft 32 becomes 110°, generates a pulse-like backward stepping signal R meaning that the main shaft 32 reversed and passed 110°.

The forward stepping signal F is supplied to the selection controller 62 and the torque restriction value generation circuit 54. The backward stepping signal R is supplied to the selection controller 62.

In the shedding command setter 60, shedding patterns for one shedding step corresponding to each heald frame 36 are preset over a plurality of picks.

As shown in Table 5, the shedding patterns in this embodiment are represented by symbols respectively showing that each heald frame 36 should be at an ascended position (shown by "1" outside the parentheses in Table 5) and that it should be at a descended position (shown by "0" outside the parentheses in Table 5).

Shedding Step No.	Heald Frame No.
	1	2	3	4	5	6	7	8
1	0	1	1	1	0	1	1	1
(1)	(3)	(3)	(2)	(1)	(3)	(3)	(2)
2	1	0	1	1	1	0	1	1
(2)	(1)	(3)	(3)	(2)	(1)	(3)	(3)
3	1	1	0	1	1	1	0	1
(3)	(2)	(1)	(3)	(3)	(2)	(1)	(3)
4	1	1	1	0	1	1	1	0
(3)	(3)	(2)	(1)	(3)	(3)	(2)	(1)
5	0	1	1	1	0	1	1	1
(1)	(3)	(3)	(2)	(1)	(3)	(3)	(2)
6	1	0	1	1	1	0	1	1
(2)	(1)	(3)	(3)	(2)	(1)	(3)	(3)
7	1	1	0	1	1	1	0	1
(3)	(2)	(1)	(3)	(3)	(2)	(1)	(3)
8	1	1	1	0	1	1	1	0
(3)	(3)	(2)	(1)	(3)	(3)	(2)	(1)

The selection controller 62 holds the value of the shedding step and has a calculation circuit for adding or subtracting the value of the shedding step (pick count value) corresponding to the forward stepping signal F or the backward stepping signal R to be inputted. For this reason, the selection controller 62 adds or subtracts the pick count value by "1" every time the forward stepping signal F or the backward stepping signal R is inputted from the stepping signal generator 58.

The selection controller 62 also returns the pick count value to 0 (or to the value of the ceiling repeat value) when the pick count value reaches the ceiling repeat value (or the lower limit repeat value 0).

The selection controller 62 reads for each heald frame 36 the shedding patterns stored in the setter 60 by using a pick count value and outputs a selection command signal Sk indicating the shedding curve corresponding to the read shedding pattern for each heald frame 36 to the drive amount output circuit 52 and the torque control value generation circuit 54.

The drive amount output circuit 52 has, besides a changeover controller 64, a timing generator 66 for generating a timing signal St which shows a start timing of one shedding step, and a shedding curve setter 68 in which a shedding curve showing a vertical position of each heald frame 36 corresponding to the rotational angle signal 0 of the main shaft 32 is set.

The timing generator 66 generates a pulse-like timing signal St, for example, when the rotational angle 0 of the main shaft 32 becomes 120°. The timing signal St is supplied to the changeover controller 64 and the torque restriction amount generated circuit 54.

The timing generator 66 outputs the pulse-like timing signal St which turns "on" every time the inputted rotational angle signal 0 becomes 120° to the changeover controller 64.

In the shedding curve setter 68, as shown in Fig. 6, a plurality of shedding curves for setting the positions of the heald frames 36 in one round of rotation of the loom, namely, between 0° and 360° of the rotational angle of the main shaft, are preset and stored. Those shedding curves are made to correspond respectively to heald frame moving patterns (1), (2) and (3) predetermined for each moving direction of the heald frames 36 so as to indicate the vertical position of each heald frame 36 corresponding to the rotational angle signal 0 of the main shaft 32 and are read in the changeover controller 64.

The heald frame moving patterns (1), (2) and (3) are respectively made to correspond to the time when the heald frame 36 moves from top to bottom, when the heald frame 36 moves from bottom to top, and from above to above (namely, the heald frame 36 does not move) as shown by a solid line, or from bottom to bottom (namely, when it does not move) as shown by a broken line.

In the shedding curve setter 68, target phase curves (see Fig. 6) showing the rotational angle of an output shaft of the electric motor 38 and the crank 44, respectively in correspondence to the main shaft rotational angle, are preset and stored.

Since the rotational directions of the electric motor 38 when the heald frame 36 moves from top to bottom and from bottom to top are the same, the target phase curves of the electric motor 38 when the heald frame moving patterns are (1) and (2) are both upward to the right.

In Fig. 6, the abscissa shows the rotational angle signal 0 of the main shaft 32. Also, the vertical lines in the columns of the shedding curve, target phase curve and rotational amount pulse respectively show the vertical position of the heald frame 36, the rotational angle of the electric motor 38 and the pulse peak value.

Consequently, the target phase curve of the heald frame moving pattern (1) is made to be a curve which increases linearly the rotational angle of the electric motor 38, namely, the rotational angle of the crank 44 from 0° to 180° till the time when the rotational angle signal is 0 = 0° to 15° before (345°), and thereafter, maintains the rotational angle of the crank 44 until the time that the rotational angle of the main shaft 32 is 0 = 0° (during the remaining 15°).

The target phase curve of the heald frame moving pattern (2) is made to be a curve which maintains the rotational angle of the crank 44 from the time when the rotational angle is 0 = 0° until the time of 15°, and thereafter, increases linearly from 180° to 360° until the rotational angle signal of the subsequent shedding step of the main shaft 32 is 0 = 0°.

The changeover controller 64 selects the shedding curve according to an inputted selection command signal Skn and outputs the pulse-like position control signal Spn according to each electric motor 38 so that the rotational angle of the electric motor 38 relative to the rotational angle signal 0 of the main shaft 32 may become the target phase curve as shown in Fig. 6.

Concretely, the changeover controller 64 reads the shedding curve stored in the setter 68 for each heald frame on the basis of the rotational angle signal 0 of the main shaft 32, the timing signal St and the first to eighth selection command signals Skn and generates the first to eighth position control signals Spn individually corresponding to the heald frames 36 on the basis of the read shedding curves to correspond to each rotational angle signal 0 of the main shaft 32.

The torque restriction value generating circuit 54 has a torque restriction element setter 72 in which torque restriction values corresponding to, for example, 120 %, 70 % and 30 % of the rating torque restriction value of the electric motor 38 are set and stored in correspondence to the continuity of the shedding motion as one of weaving elements, and a torque restriction value generator 74 for outputting the read torque restriction values from the torque restriction element setter 72 to the position control portion 42.

More concretely, the torque restriction value generating circuit 54 changes the torque restriction value to any of ranks A, B and C in correspondence to the continuity of the shedding motion when a period for the main shaft 32 to rotate one round is defined as one motion period. The ranks A, B and C of the torque restriction values have a relationship of A > B > C, and the rank A is set at a continuous rating value (100 %) or a value set in its neighborhood, or in a range not exceeding a short-time rating value and at a value higher than the continuous rating value (for example, 120 %).

Rank A is set at 120 % of the rated current of the electric motor 38 so as to be able to surely drive the electric motor 38 when starting and stopping operation of the electric motor 38.
Rank B is set at 70 % of the rated current of the electric motor 38 so that heat generation of the electric motor 38 can be suppressed and the inertia force can be utilized for saving energy during continuous motion of the electric motor 38.

Rank C is set at 30 % of the rated current of the electric motor 38 by further making the torque restriction value smaller while the electric motor 38 is under stoppage.

The concrete numerical values of ranks A, B and C are only examples and are appropriately determined according to the actual state of the specification of the electric motor.

The torque restriction value generator 74 outputs the torque restriction value S2 when the timing signal St is generated (120°) by judging the continuity of the shedding motion, as mentioned later, from the selection command signal Sk of the shedding curve to be renewed at the time of generation (110°) of the forward stepping signal F as well as from the selection command signal Sk of the past several shedding patterns before.

The torque restriction value generator 74 performs: (A) motion at the start of the operation, for making the torque restriction value 120 % of the rating torque of the electric motor 38 until reaching a predetermined number of picks after starting operation of the loom; and (B) thereafter, commanded by a unit of one pick, motion at the time of the continuous operation for making the torque restriction value any one of a group of 120 % (rank A), 70 % (rank B) and 30 % (rank C) of the rating torque of the electric motor 38 from an output mode, that is, the continuity of the shedding motion of a shedding selection command (command for selection of the shedding curve) corresponding to the pick just before and the pick before it and the present pick.

As shown in Fig. 7, each position control portion 42 controls the rotational angle of the electric motor 38, in turn, the rotational angle of the crank and the vertical motion of the heald frame, by performing a feedback control of the electric motor 38, based on the position control signal Spn and torque restriction value S2n. The rotational angle of each electric motor 38 is detected as a pulse signal Se generated according to the rotation of the electric motor 38 in an encoder 76.

Each position control portion 42 receives the pulse signal Se representing the rotational angle of the electric motor 38 corresponding to itself in a deviation detection circuit 78 and in a speed control circuit 80 through a speed signal conversion circuit 83, and further in a current control circuit 82 through a rotational angle conversion circuit 85, thereby controlling the rotational angle of the electric motor 38 in correspondence to the position control signal Spn.

The speed signal conversion circuit 83, which is a frequency-voltage conversion circuit, converts the inputted pulse signal Se into a voltage corresponding to its frequency and generates a speed signal Sv representing an actual speed. The rotational angle conversion circuit 85 counts the inputted pulse signal Se and generates an angle signal t representing the rotational angle of the electric motor 38.

The deviation detection circuit 78 receives the position control signal Sp and pulse signal Se. On the other hand, a reciprocal counter which is built in and to which both signals Spn and Se are inputted detects a deviation of the input numbers of two pulse signals and outputs the detected deviation to the speed control circuit 80 as a deviation signal ΔP.

The speed control circuit 80 computes a speed deviation on the basis of the deviation signal ΔP and speed signal Sv to be inputted in the speed control circuit 80 and outputs the computed speed deviation to the current control circuit 82 as the speed deviation signal ΔV.

The current control circuit 82 computes a current command value corresponding to the two deviations from the speed deviation signal ΔV and a current value signal Sif detected by a current sensor 81. The current control circuit 82 also performs torque restriction by outputting the current to the electric motor 38 on the basis of the current command value to be determined so as not to exceed the torque restriction value S2 as well as on the angle signal t, and controls the current of the electric motor 38.

By this, the position control portion 42 restricts the current to be supplied to the electric motor 38 so that the output torque value of the electric motor 38 may not exceed the torque restriction value S2. In other words, the current control circuit 82 can drive the electric motor 38 according to the speed deviation signal ΔV and in a state that the output torque is restricted within a range of the torque restriction value S2.

More concretely, as shown in Fig. 8, the current control circuit 82 includes: a current calculator 84 for operating a current command value I corresponding to the speed deviation signal ΔV and outputting to an addition terminal of an addition point 86; a multiplier 88 for outputting a value obtained by multiplying the current value signal Sif representing the current flowing in the electric motor 38 by a current loop gain g to a subtraction terminal of the addition point 86; a limiter circuit 90 for outputting the current command value signal Si within a range that the deviation current value ΔI showing a result computed at the addition point 86 does not exceed the torque restriction value S2; and a current generation circuit 92 for generating the current to be supplied to the electric motor 38 on the basis of the current command value signal Si and so that the electric angle signal t of the electric motor 38 may be located within a predetermined angular range.

The foregoing control device 30 vertically drives the heald frames 36 such as in the timing charts shown in Figs. 9 and 10.

Figs. 9 and 10 are timing charts showing as a time series the above-mentioned motion flow in continuous operation in the first heald frame 36 at the time of the shedding patterns (1/3 · 3/1).

The timing chart shown in Fig. 10 is an example of determining a torque restriction value by judging the continuity of the shedding motion according to a result of comparison between the shedding pattern in the previous shedding step in the switching timing of the shedding motion during an operating period of the loom and that in the present shedding step. The timing chart shown in Fig. 9 is an example of determining a torque restriction value which is different between the acceleration time at the time in starting operation of the loom and a state of steady rotation thereafter. Such a motion is realized by the flowcharts shown in Figs. 11 through 14 to be mentioned later.

In Figs. 9 and 10, the abscissa shows in the first heald frame 36 the rotational angle signal 0 of the main shaft 32, and the vertical axis shows (A) an operation start signal So, (B) the forward stepping signal F, (C) a shedding step No., (D) No. of heald frame moving pattern designated by the selection command signal Sk to be outputted from the shedding selection command circuit 56, (E) the timing signal St, (F) the vertical shedding amount of the heald frame, (G) a state of a drive pulse outputted to the electric motor 38, and (H) the torque restriction value.

Also, the torque restriction value generator 74 determines during control operation a torque restriction value according to the flowcharts shown in Figs. 11 through 14.

With reference to Figs. 11 through 14, the motion of the control device 30 in continuous operation is explained in the following.

Suppose a loom whose shedding step No. (namely, the pick count value) is "1" and in stoppage at the main shaft angle of 300°. Fig. 9 shows a motion timing chart relative to the first heald frame 36 whose frame No. is 1 (namely, in front row). In the loom which stops in this state, the selection controller 62 outputs a selection command signal Sk of "0" in the state of shedding step No. 1 as shown in Table 5, and the first heald frame 36 has been moved to a position for being somewhat in an under shed shedding state by a position command signal SP1 outputted like pulse from the position command portion 40 and is in a synchronized state relative to the rotational angle 0 of the main shaft of the loom.

Fig. 9 is an example that, during an operation period when the rotational speed of the loom reaches a steady rotational speed, the torque control value generator 74 judges the continuity of the shedding motion of the frame No. 1 heald frame 36 and changes the corresponding torque restriction value as well as an example that, during the period from after starting operation of the loom to plural picks (3 picks in the illustration) after starting operation, the torque control value generator 74 changes to a constantly high torque restriction value in place of the above in order to avoid a delay in driving of the heald frame by inertia force.

(1) Explanation of a pick right after starting operation of the loom

Before starting operation of the loom, flag A for changing the rotational speed of the torque restriction value generator 74 is "off."

In this state, as shown in Fig. 9, for example, when the rotational angle signal 0 of the main shaft 32 is 300°, the operation start signal So is temporarily turned "on" by an operator.

At this time, the shedding pattern, which is shedding step No. 1 shown in Table 5, the position command portion 40 outputs a position control signal Sp so as to move the first heald frame 36 to a bottom dead center.

The torque restriction value of the pick right after starting operation of the loom (the first pick) at this time is computed as follows:

When the operation start signal So turns "on," operation of the loom is started. By this, as shown in Fig. 11, the torque restriction value generator 74 judges whether flag A is "on" or "off" (step 101).

A control process such as the flowcharts in Figs. 11 through 14 is carried out, not only at the time of the input of the operation start signal So and the input of a rotational speed change signal SA, but every time the forward stepping signal F is generated (when passing 110°) during operation of the loom. Also, flag A to be mentioned later is a flag to be set by the input of the operation start signal So or the input of the rotational speed change signal SA.

The torque restriction value generator 74, when flag A is "on" as a result of judgment in step 101, shifts through B to a shedding curve selection process flow shown in Fig. 12, and when flag A is "off," shifts to judgment as to whether the operation start signal So for "on" is inputted or not (step 102).

The torque restriction value generator 74, when the operation start signal So for "on" is inputted as a result of judgment in step 102, shifts through B to the shedding curve selection process flow shown in Fig. 12, and otherwise, through A to the rotational speed change process shown in Fig. 13.

In the shedding curve selection process flow shown in Fig. 12, the torque restriction value generator 74 makes another judgment as to whether flag A is "on" or "off" (step 201).

At the time of carrying out this step 201, flag A should have already been "off' as mentioned above, but it is sometimes "on."

Therefore, if flag A is "off" as a result of the judgment in step 201, the torque restriction value generator 74 turns flag A "on" and turns the pick count value of the selection controller 62 to "0" (step 202), and then sets a torque restriction value ILO of the torque restriction value generator 74 at 120 % of the rating torque of the electric motor 38 (namely, rank A) (step 203).

By this, the torque restriction value ILO is set at the value of rank A. Thereafter, the torque restriction value generator 74 shifts to step 401 shown in Fig. 14.

As shown in Fig. 14, in step 401, the torque restriction value ILO is immediately renewed to a torque restriction value IL, and the torque restriction value generator 74, after outputting the torque restriction value IL to the position control portion 42 as a torque restriction value S2, finishes computing the torque restriction value of the pick of right after starting operation of the loom (in other words, the first pick after starting operation).

On the other hand, the changeover controller 64 of the drive amount output circuit 52 outputs the position control signal Sp1 such as shown in the rotational amount pulse waveform of (1) in Fig. 9 (G) and Fig. 6.

As a result of the above, the first position control portion 42 drives the first electric motor 38, based on the position control signal Sp1 and torque restriction value S21, by the current within the range of the torque restriction value S2 or less as set at rank A, namely, 120 % of the rating torque.

While the first electric motor 38 which was stopped until just before is suddenly driven on the basis of the position control signal Sp, great inertia force of the crank 44 not rotating acts on the electric motor 38.
However, since the torque control value S21 is set at rank A which is to be 120 % of the rating torque, even if the electric motor 38 temporarily becomes overloaded, a current greater than the rating current flows in the electric motor 38, so that the electric motor 38 rotates the crank 44 and moves the heald frame 36 rapidly from top to bottom.

(2) Explanation of the second and third picks of right after starting operation of the loom

In this case, the control device 30 outputs the pulse-like forward stepping signal F from the stepping signal generator 58 when the rotational angle signal 0 of the main shaft 32 becomes 110° (see Fig. 9 (B)).

The selection controller 62 selects a set value corresponding to the shedding steps 2 and 3 of Table 5 and outputs the selection command signal Sk of the shedding curve (2) in Table 5.

On the other hand, in the torque signal generator 74, when flag A is judged to be "on" in step 101, and as a result of the judgment in step 201, if flag A is "on," the control device 30 increases the pick count value by "1" as shown in Fig. 12 (step 204). As a result, the count value becomes 1 or 2.

Next, the torque restriction value generator 74 stores the selection command signal Sk of one pick before the selection command signal Sk of the pick of just before, the selection command signal Sk of just before and the present selection command signal Sk respectively as the third selection command, second selection command and first selection command (step 205).

If the present one is the second pick after starting operation, the third selection command is not stored. The first and second selection commands in the second pick are kept at a value of "1" or "0" showing vertical positions of the heald frame 36 shown in Table 5. The first, second and third selection commands in the third pick are kept respectively at the values of "1," "1," and "0."

Next, the torque restriction value generator 74 judges whether the pick count value has reached a predetermined value (3 in this embodiment) (step 206), and then shifts to step 401.

As a result of the above, in the second and third picks, the torque restriction value ILO is set at the first pick value (the value of rank A), so that, in step 401, the value of the torque restriction value IL is kept at the value of rank A, and the torque restriction value generator 74, waiting for inputting of the timing signal St, outputs the torque restriction value ILO as the torque restriction value S2.

(3) Explanation of the fourth pick of right after starting operation of the loom

In this case, the control device 30 judges that flag A is "on" in step 101, judges again that flag A is "on" in step 201, and then in step 204, increases the pick count value of the torque restriction value generator 74 by "1." As a result, the pick count value of the torque restriction value generator 74 becomes 3.

Next, the torque restriction value generator 74, in step 205, stores the selection command signal Sk of one pick before the selection command signal Sk of the pick of just before, and the selection command signal Sk of just before and the present selection command signal Sk respectively as the third selection command, second selection command and first selection command.

Since pick No. at this time is the fourth pick after starting operation, the selection command signals Sk from the first to the third have already been stored in the torque restriction value generator 74.

Then, the torque restriction value generator 74 judges whether the pick count value of the torque restriction value generator 74 has reached a predetermined value (3 in this embodiment).

As a result, the pick count value having reached a predetermined value, the torque restriction value generator 74 turns flag A "off" and shifts to step 302 shown in Fig. 13.

As shown in Fig. 13, the torque restriction value generator 74 judges whether the first selection command and the second selection command are the same or not in step 302 so as to set the torque restriction value.

The torque restriction value generator 74 judges whether the second selection command and third selection command are the same or not in step 303 if the first selection command and second selection command are different, and in step 304 if the first selection command and second selection command are the same, respectively.

As a result of judgment in step 303, if the second selection command and third selection command are the same, the torque restriction value generator 74 sets the value of the torque restriction value ILO at the value of rank A (step 305) and shifts to step 401.

As a result of judgment in step 302, if the second selection command and third selection command are different, the torque restriction value generator 74 sets the value of the torque restriction value IL0 at the value of rank B (step306) and shifts to step 401.

As a result of judgment in step 304, if the second selection command and third selection command are the same, the torque restriction value generator 74 sets the value of the torque restriction value ILO at the value of rank C (step 307) and shifts to step 401.

As a result of judgment in step 304, if the second selection command and third selection command are different, the torque restriction value generator 74 sets the value of the torque restriction value ILO at the value of rank A (step 308) and shifts to step 401.

In step 401, the value of the torque restriction value IL is set at the value of the torque restriction value ILO, and the torque restriction value generator 74, waiting for the input of the timing signal St, outputs the torque restriction value ILO as the torque restriction value S2.

Regarding, for example, the heald frame which is stationary during weaving operation, when movement (shedding motion) of the heald frame occurs newly because the shedding step No. is increased by one, the torque necessary for starting movement of the heald frame because the torque restriction value of rank A is selected due to passing step 305 is enabled to be outputted.

Also, in case the heald frame does not move even if the shedding step No. is increased by one, the torque restriction value of rank C is selected due to passing through step 307, thereby enabling to restrict to an output torque necessary for maintaining the position of the heald frame.

Also, in case the heald frame moving during weaving operation continues its movement (shedding motion) when the shedding step No. is increased by one, the torque restriction value of rank B is selected by passing through step 306, thereby restricting the output torque, useless motion relative to deceleration and acceleration for accurately following the shedding curve is restricted. As a result, the inertia force is effectively used, enabling to drive the heald frame.

When the heald frame does not move and is stationary, the torque restriction value of rank A is selected when passing through step 308, enabling to output the deceleration torque necessary for making the moving heald frame stationary.

Thus, every time the shedding step No. is increased by one, the continuity of the motion of the heald frame in the past two picks and future one pick is judged, and when the motion of the heald frame (including the stationary state of the heald frame) has continuity, more concretely, when the heald frame in the past two picks and future one pick continues to move or continues to be stationary, the torque restriction value in the period of future one pick is set on the low side in correspondence to these states.

Also, when the motion of the heald frame does not have continuity, or more concretely, when the heald frame which moved in the past two picks does not move in the future one pick but is turned stationary, or when the heald frame which was stationary in the past two picks is moved in the future one pick, the torque restriction value in the future one pick period is set on the high side in correspondence to these states.

In other words, by passing through the processes of steps 301 through 401, the torque restriction value is set on the low side when the motion of the heald frame has continuity, so that useless deceleration or acceleration is suppressed to perform driving by making use of action force (inertia force) while the heald frame is moving and when a torque is required for moving or stopping the heald frame, the torque restriction value is set on the high side to output a necessary torque, thereby improving an energy saving effect.

While the torque restriction value is set in correspondence to whether there is continuity of motion of the heald frame or not, it is also possible to set torque restriction values different between a case of starting movement from the stationary state and a case of becoming stationary from the moving state.

(4) Explanation of motion at the time of continuous operation

In this case, operation of the loom has already been started, and when the rotational angle signal 0 becomes 110°, the control device 30 outputs the pulse-like stepping signal F from the stepping signal generator 58, so that the torque restriction value generator 74 performs the process of the above-mentioned flowchart again. And yet, since the operation start signal So is turned "off" as shown in Fig. 9 (A) and, moreover, in previous step 207, flag A has already been turned "off," the torque restriction value generator 74, judging as "off" in step 101 for judging flag A, proceeds to step 102.

Since in step 102 the operation start signal So is "off" as mentioned above and no command for changing the rotation of the main shaft 32 is inputted, the torque restriction value generator 74 shifts to step 301 shown in Fig. 13.

As shown in Fig. 13, the torque restriction value generator 74 stores, in step 301, the selection command signal Sk of one pick before the selection command signal Sk of the pick of just before, and storing the selection command signal Sk of just before and the present selection command signal Sk respectively as the third selection command, second selection command and first selection command, shifts to step 302.

The torque restriction value generator 74, in

steps

302, 303 and 304, as already mentioned, judges whether the first, second and third selection commands are the same or not, and according to the result, and shifting to step 305, 306, 307 or 308, sets the torque restriction value ILO at any one of ranks A, B and C, and then shifts to step 401.

In step 401, the torque restriction value generator 74, setting the value of the torque restriction value IL as the value of the torque restriction value ILO, and after waiting for the input of the timing signal St, outputs as the torque restriction value S2. Consequently, when the total number of the shedding steps are counted as eight and the shedding patterns shown in Table 5 are set as shown relative to the first to eighth heald frames, the torque restriction value generator 74 outputs the torque restriction value S2 corresponding to the rank as shown in Table 6 in each shedding step to each heald frame.

The above-mentioned control device 30 (torque restriction value generator 74) may be changed as follows.

Instead of judging the continuity of the shedding motion during operation, it is possible to judge preliminarily before operation and to enable to generate the selection signal relative to the torque restriction value corresponding to the number of picks, to generate the selection signal based on the pick count value during operation, and to change the torque restriction value.

The changeover during weaving operation is not limited to the continuity of the above-mentioned shedding motion regarding a weaving element, but the torque restriction value may be determined, taking into account of the following, and two or more may be combined.

For example, like the first embodiment, by determining the factor for computing the torque restriction value preliminarily to meet a setting mode of the weaving element to be mentioned later, the torque restriction value is obtained and set from the factor selected in correspondence to the setting mode of each weaving element. It is desirable to set the torque restriction value in such a case by preliminarily obtaining the torque restriction value in correspondence to a combination of each setting mode prior to weaving operation and to set by selecting them during weaving operation, but it is possible to set it by calculation every time the setting mode is changed over during weaving operation.

For example, it is possible to select a dwell angle (an angle for maintaining in the maximum shedding state) during weaving operation, a cross timing of the shedding motion, and shedding curves different in composing elements of the shedding curves such as shedding amount. In this case, it suffices to set a torque restriction value according to a shedding curve and to change over; for example, when selecting a shedding curve with a shortened driving period, the torque restriction value may be set on the high side.

The torque restriction value may be changed to correspond to the moving direction of the heald frame 36 (from top to bottom or from bottom to top). More concretely, in case the dead load of the heald frame 36 acts greatly on the rotation of the electric motor 38, the torque restriction value may be set on the low side.

In order to improve weft placing property, the warp tension is changed according to the weft inserting pick during operation of the loom. The above-mentioned torque restriction value of the shedding device may be changed over in correspondence to such a change. More concretely, when the warp tension is lowered, the torque restriction value is also set on the low side.

In order to insert plural kinds of wefts different in difficulty in weft insertion, when changing the rotational speed of the main shaft 32 of the loom in correspondence to the weft insertion pick during weaving operation, the torque restriction value is changed over in correspondence to the change. More concretely, when the rotational speed of the main shaft 32 is slow, the torque restriction value is set on the low side. In this case, in step 102 shown in Fig. 11, in the control device 30 of the electric shedding device, flag A is "off" in step 101, and when a change in rotational speed of the main shaft 32 is judged in step 102 and in case the rotational speed of the main shaft 32 is judged to have changed, shifts to step 202 through step 201 of Fig. 12 like when the operation start signal So turned "on."

Regarding changeover of the torque restriction value, in the above-mentioned second embodiment, the main shaft 32 of the loom is enabled to change over every time it rotates one round, but it is possible to change by a predetermined angle of one rotation or less or one rotation or more, and further, it is possible to change per plural rounds of rotation such as twice or more.

Changeover of the torque restriction value may be performed by judging a change in continuity of the shedding motion or may be performed in correspondence to a changeover of textile of a cloth.

For example, relative to the first process corresponding to the operation start time in case of a plain weave (namely, during steady operation, or when the heald frame does not stop and is always moving), the torque restriction value may be changed over on the low side in the second process after reaching a steady operational speed.

In case of a loom for changing the rotational speed of the loom according to the difficulty in weft insertion in correspondence to a change in rotational speed of the loom, a changeover signal of the rotational speed of the loom is inputted to the torque restriction value generation circuit as the torque restriction value generator 74.

While changeover of the torque restriction value may be performed according to the rotational angle of the main shaft 32, it may be changed over according to an elapsed time from a reference angle.

Regarding the above-mentioned second embodiment, the torque restriction value may be set to differ in consideration of the heald frame No. (frame No.) such as in case of the first embodiment.

The internal constitution of the shedding control device may undergo a process by hardware concerning a series of processes as illustrated or a process by a micro-processor as well as software.

The present invention is not limited to the foregoing embodiments but can be variously changed without departing from its spirit.

Claims

A control method of an electric shedding device of such a type as driving each of plural heald frames (36) by an exclusive electric motor (38) and restricting an output torque of the electric motor (38) according to a predetermined torque restriction value, comprising the steps of:

obtaining torque restriction value of the electric motor (38) according to a setting mode for at least one weaving element, and

setting the obtained torque restriction value for the electric motor (38).
A control method according to claim 1, wherein a plurality of torque restriction values are preset according to the setting modes of the weaving element; and
wherein in the step of obtaining the torque restriction value of the electric motor (38), a torque restriction value according to the setting mode of the weaving element is selected.
A control method according to claim 1, wherein a plurality of factors for computing a torque restriction value corresponding to the setting modes of the weaving element are preset for each weaving element; and
wherein, in the step of obtaining the torque restriction value of the electric motor (38), factors corresponding to the setting mode of the weaving element are selected for each weaving element, and the torque restriction value obtained by operation from the selected plurality of factors is set as the torque restriction value of the electric motor (38).
A control method of an electric shedding device of such a type as driving each of plural heald frames (36) by an exclusive electric motor (38) and restricting an output torque of the electric motor (38) according to a predetermined torque restriction value, comprising the step of:

setting the torque restriction value of the electric motor (38) according to heald frame No.
A control method of an electric shedding device of such a type as driving each of plural heald frames (36) by an exclusive electric motor (38) and restricting an output torque of the electric motor (38) according to a predetermined torque restriction value, comprising the step of:

obtaining and setting the torque restriction value of the electric motor (38) according to a setting mode for at least one weaving element and heald frame No.
A control method of an electric shedding device of such a type as driving each of plural heald frames (36) by an exclusive electric motor (38) and restricting an output torque of the electric motor (38) according to a predetermined torque restriction value, comprising steps of:

enabling to change over setting mode of at least one weaving element during weaving operation, and

during weaving operation, obtaining and setting a torque restriction value of the electric motor (38) in correspondence to a changeover of the setting mode of the weaving element.
A control method of an electric shedding device according to claim 6, wherein a plurality of the torque restriction values are set in correspondence to a changeover of the setting mode of a weaving element, and
wherein a torque restriction value corresponding to the changeover of the setting mode is selected and set at the time of the changeover of the setting mode during weaving operation.
A control method of an electric shedding device according to claim 7, wherein the weaving elements include at least one selected from a group including continuity of the shedding motion from several picks before up to the changeover, composing elements of a shedding curve, direction of the shedding motion from the changeover, external force acting on heald frames (36) and the rotational speed of a loom.
A control method of an electric shedding device according to any one of claims 6 through 8, wherein each setting mode of plural weaving elements during weaving operation can be changed over;
wherein a plurality of factors of the torque restriction value are set in correspondence to each setting mode;
wherein a torque restriction value corresponding to the changeover of the setting mode is selected for each weaving element,
wherein at the time of the changeover of the setting mode during weaving operation, the torque restriction value is obtained by operation from the selected plural factors, and
wherein obtained torque restriction value is set as the torque restriction value of the electric motor (38).
A control method of an electric shedding device of such a type as driving each of plural heald frames (36) by an exclusive electric motor (38) and restricting an output torque of the electric motor (38) according to a predetermined torque restriction value, comprising the steps of:

presetting the output torque restriction values of the electric motor (38) in correspondence to a first process for accelerating or decelerating the rotational angle speed of a main shaft, and a second process for maintaining the rotational angle speed of the main shaft; and

in the first and second processes at the time of driving the shedding device, driving the electric motor (38) by restricting the output torque of a drive motor on the basis of the output torque restriction values corresponding to those processes.