EP0465928A1

EP0465928A1 - System to control the feeding of nozzles conveying the weft along the shed of fluid jet looms

Info

Publication number: EP0465928A1
Application number: EP91110552A
Authority: EP
Inventors: Pezzoli Luigi
Original assignee: Vamatex SpA
Current assignee: Vamatex SpA
Priority date: 1990-06-27
Filing date: 1991-06-26
Publication date: 1992-01-15
Also published as: IT9020779A1; IT1250918B; IT9020779A0

Abstract

In a system to control the feeding of nozzles conveying the weft along the shed of fluid jet looms - allowing to vary the weft motion law along the shed by widening the range of adjustment and making it more precise - the feeding of the single fluid jet nozzles or groups of nozzles (G1, G2) is controlled by means of at least two solenoid valves (15, 16, 17, 18, 19, 20) with mutually connected outlets, each of said valves being operated independently by an electronic device (DE) depending from the electronic system which controls the working of the loom.

Description

The present invention concerns a system to control the feeding of nozzles conveying the weft along the shed of fluid jet looms, said system allowing to vary the weft motion law along the shed by widening the range of adjustment and making it far more precise than with the conventional systems.
Fluid jet looms are well known and now widely diffused: the weft is fed therein and conveyed along the warp shed by means of fluid jets - especially air jets - blown by a main nozzle facing the inlet of the shed and by a set of secondary nozzles distributed along said shed and fed either singly or in groups.
In the constructions known so far, each of said nozzles or groups of nozzles receives the fluid (air) required for its working from a duct controlled by a single solenoid valve, operated by the electronic devices provided to transfer the weft in synchronism with the other functions of the loom, as that of the sley and of the weave device.
Said solenoid valve receives air from a feeding system in which the pressure value can be varied manually or automatically by means of pressure regulators, in times which are considerably longer than the length of a blowing phase in each cycle of the same solenoid valve. Furthermore, said pressure regulators always control more than one solenoid valve and thus more nozzles or groups of nozzles.
It ensues that the air pressure for the jets - and thus weft transport along the shed - can be set only in undesirably long times and with no possibility to differentiate the pressure for the various nozzles or groups of nozzles.
It is evident, on the other hand, that a fast setting of the pressure is apt to improve the efficiency of weft transport along the shed and, therefore, the working of the loom in all its steps, in the most different working conditions and using any type of yarns; furthermore, the individual control of each nozzle or group of nozzles - both for what concerns the pressure of the fluid jet and for what concerns the blowing times - would also greatly improve the working of the loom, as well as providing considerable advantages in reducing energy consumption.
The present invention proposes to reach both these objects with a system to control the feeding of nozzles conveying the weft along the shed of fluid jet looms, which allows to set the pressures and blowing times for each single nozzle or group of nozzles.
Said system is essentially characterized in that the feeding of the single fluid jet nozzles or groups of nozzles is controlled by means of at least two solenoid valves with mutually connected outlets, each of said valves being operated independently by an electronic device depending from the electronic system which controls the working of the loom. The system is apt to control both the feeding of the main nozzle and that of the secondary nozzles or groups of nozzles of the loom.
In said system, the solenoid valves can be fed together from a common pressure source or, alternatively, in a separate way from different pressure sources.
It actually seems preferable to use groups of three solenoid valves to control the feeding of single nozzles or groups of nozzles.
It should be pointed out, furthermore, that the solenoid valves can be independently operated by said electronic device in times and for lengths of time which can be differently prearranged for each solenoid valve and for each type of loom operation, and which can even be varied for each working cycle.
The invention is now described in further detail, by mere way of example, with reference to the accompanying drawings, which illustrate two preferred embodiments thereof and in which:

Fig. 1 is a diagram showing a first embodiment of the system according to the invention, to control the feeding of nozzles of fluid jet looms;
Fig. 2 is a diagram similar to that of fig. 1, showing a second alternative embodiment of the control system according to the invention; and
Figs. 3 and 4 are diagrams illustrating the effects of the control systems shown in figs. 1 and 2 respectively.

As pointed out, the system according to the invention provides for each electronic device controlling single nozzles (as the main loom nozzle) or groups of nozzles (as the secondary nozzles) to use at least two solenoid valves, the capacity of which should be at least equal to that of the single solenoid valve of conventional devices, said solenoid valves having mutually connected outlets to feed the nozzle or groups of nozzles controlled by the device, and being in turn fed either separately or together (in this last case also their inlets are mutually connected).
More generally, the solenoid valves are chosen so that the single operation of only one of them does not allow to reach the top pressure value in the circuit downstream of said valve, in relation to a given inlet pressure Pi upstream thereof. Whereas, the top pressure value in the circuit downstream of the valves is meant to be reached only when all the valves are open.
Figure 1 shows a group G of three secondary nozzles 1, 2, 3, of a fluid jet loom; the group G is fed by a single duct 4 into which converge the outlets 5, 6, 7, of three solenoid valves 8, 9, 10, being in turn fed, at the same pressure Pi, from a reservoir 11 through the inlets 12, 13, 14.
Figure 2 shows instead two groups G1 and G2 of three secondary nozzles; the group G1 is fed by the solenoid valves 15, 16, 17, and the group G2 is fed by the solenoid valves 18, 19, 20, similarly to the group G of figure 1. Nevertheless, in this case, the valves are fed separately at different pressures - Pi1 for the valves 15 and 18, Pi2 for the valves 16 and 19, and Pi3 for the valves 17 and 20 - by way of ducts 21, 22, 23, controlled by pressure regulators 25, 26, 27.
Both in the case of figure 1 and in that of figure 2, the solenoid valves are operated by an electronic device DE, depending from the electronic system controlling the whole working of the loom.
It is evident that, when - in the system of figure 1 - a single valve (for example 8) of the group G is opened, a working fluid pressure equal to P1 Pi is reached in the nozzles 1, 2, 3, Pi being the feeding pressure of the solenoid valves (i.e. the pressure in the reservoir 11). The value of P1 depends on the ratio between the outflow section of the open solenoid valve and the section of the nozzle or nozzles being fed, as well as - obviously - on the drops of pressure. One should bear in mind that, as narrow tubes and pressures of 2-4 bar are normally adopted, the effect of the pressure drops is considerable.
If now the second valve (9) and then the third valve (10) are opened, the pressure of the working fluid rises (reaching respectively P2 and then P3) and tends to get close to the pressure Pi.
By closing again the three valves, the working pressure is - obviously - correspondingly reduced.
The diagram of figure 3 clearly illustrates how it may thus be possible to set the pressure (ordinates) in the nozzles during the weft insertion cycle in the loom, - by simply varying the energizing times (abscissae) of the solenoid valves 8, 9, 10.
Likewise behaves the system of figure 2. Nevertheless, in this case, to set the pressure of the working fluid it is possible not only to act on the energizing times of the solenoid valves 15, 16, 17, or 18, 19, 20, but also to choose which of said valves can be opened and/or closed, seen the different values of the pressures Pi at which the three valves are fed: the range of adjustment is thus even wider, as clearly results from the diagram of figure 4 drawn on the same scale as that of figure 3.
It appears evident that the essential advantage of the system according to the present invention lies in the possibility to effect weft yarn transport along the shed of fluid jet looms in a far more flexible way than with the conventional systems.
But there are additional advantages; it is for instance possible to lengthen the blowing times by using a reduced number of solenoid valves, keeping the weft well stretched in the shed and using up far less energy.
It is understood that, although the accompanying drawings refer to groups of secondary nozzles, the system is also provided - as besides indicated several times - to feed the main loom nozzle; in this case, by modulating the blowing times, one realizes a consequently modulated rate of the working pressures.
As already stated, the capacity of the single solenoid valves used in the system according to the invention should be smaller than the capacity of one single equivalent solenoid valve: this allows to realize, with small valves, a compact body which is not necessarily greater in size than the body of a single equivalent valve. The practical solution to the problem is favoured by the recent appearance on the market of miniaturized solenoid valves.
It is understood that there can be other practical embodiments of the aforecited control system, differing from those described or comprising modifications and variants thereof, without thereby departing from the scope of the present invention.

Claims

System to control the feeding of nozzles conveying the weft along the shed of fluid jet looms, allowing to vary the weft motion law along the shed by widening the range of adjustment and making it more precise, characterized in that, the feeding of the single fluid jet nozzles or groups of nozzles is controlled by means of at least two solenoid valves with mutually connected outlets, each of said valves being operated independently by an electronic device depending from the electronic system which controls the working of the loom.
Control system as in claim 1), wherein said solenoid valves are fed together from a common pressure source.
Control system as in claim 1), wherein said solenoid valves are fed separately from different pressure sources.
Control system as in claim 1), wherein groups of three solenoid valves are provided to control the feeding of single nozzles or groups of nozzles.
Control system as in claim 1), operating on the main weft conveying nozzle.
Control system as in claim 1), operating on a secondary nozzle or on a group of secondary nozzles.
Control system as in claim 1), wherein said solenoid valves are independently operated by said electronic device, in times and for lengths of time which can be differently prearranged for each solenoid valve and for each type of loom operation, and which can even be varied for each working cycle.