EP3191753A1 - Solenoid valve with in-line balancing rod - Google Patents

Abstract

The present invention relates to the field of solenoid valves, particularly of interest in the present invention there are the direct command valves, more particularly those preferably using balancing rods. In this connection a direct command solenoid valve is disclosed, being adapted to operate in conditions of both maximum high pressure and high flow rates, with pressure balancing means.

Description

SOLENOID VALVE WITH IN-LINE BALANCING ROD

The present invention relates to the field of solenoid valves, more particularly solenoid valves with direct command and most preferably the valves using balancing rods.

It is well known that direct command solenoid valves are used in the most diversified sectors and are extremely widespread in view of their great versatility of use.

More particularly the direct command solenoid valves include either normally closed or normally open solenoid valves.

For instance, among the traditional fields of use of direct command solenoid valves, for the objects of the present invention there is a particular interest in the field of fluid controls, such as water, or fluidic foodstuffs like syrups, or even in the petrochemical sector. Anyway these valves may be used also in the pneumatic and chemical sector. With particular reference to the field of controlling passage of fluids, like in the alimentary sector, normally closed or normally open solenoid valves with direct command are well known and widespread.

With regard to the direct command solenoid valves, it is known that these solenoid valves have rather limited flow rates, thus their performances are limited by the flow rate and the poor pressure attained by the processed fluid.

Consequently to increase the flow rate of the solenoid valve, it is necessary to supply higher feeding powers to the coil, with related increase of energy consumption and corresponding costs.

Moreover in this kind of valves a greater wear of the sealing surfaces, such as orifices and gaskets, is often recurring.

More particularly, for instance in a normally closed two-way solenoid valve, the operative pressure is dependent from and proportional to the orifice area, so that in any case the attainable pressures are limited and determined by the orifice diameter (with the same coil power).

In addition, in a direct command two-way solenoid valve, the movement of the movable core (moved by the coil energization generating a magnetic force acting on the movable core) corresponds to opening or closing an orifice. Therefore, if high flow rates are required, a large movement of the movable core and a broad orifice are required (since large movements correspond to large flow rates), thus it is necessary to provide for a large movement of the movable core, with consequent increase of the coil power and corresponding increase of the magnetic force. Therefore it is apparent that to have considerable flow rates, it is necessary to increase correspondingly the coil power, with consequent heavy economic burden.

Consequently it results that the maximum operative pressure of the solenoid valve is depending not only upon the orifice diameter, that is the fluid flow rate, but also upon the magnetic force that can be generated by the coil.

For this reason it is possible to attain high flow rates and high operative pressures only by increasing considerably both the coil power and the dimensions of the relevant magnetic circuit.

Examples of some types of the above mentioned valves are reported in document WO 98/26168 disclosing a normally closed direct command two-way solenoid valve particularly comprising ducts for discharging possible leaks into a sealing member. Pressure balance in this solenoid valve occurs through two orifices thus giving rather high performances to this valve. It is to be noted that implementation of two orifices causes the valve to be rather complex and full of components, in addition to requiring leak control of both orifices. Moreover all its embodiments allow operation only with direct current, thus failing to meet the demand of a large part of the market that needs to work under alternate current.

In addition document DE 3804011 discloses a direct command two-way solenoid valve, adapted to modulate a liquid or gaseous flow inside pipes or ducts for discharging possible leaks of sealing members, wherein said valve makes a pressure balance and can operate under alternate current. In this document the main object is to reduce the radial forces generated during the operative stage which otherwise lead to a quick wear and failure of said valve, in this case said valve has constructional limits just due to its specific use to work specifically inside a pipe. It is to be noted that for this reason the orifices for fluid passage have reduced dimensions due to the structural limitations, so that this valve in any case cannot allow variable and especially high flow rates.

Document WO 2004/113774 discloses a pressure control device comprising a first and a second valve member, the one normally closed and the other normally open, respectively, including passage orifices all with identical diameters in order to balance this valve group in any position. Said device cannot operate under alternate current and does not concern optimization of flow rates and performances, but has only the object of balancing precisely the pressures in any opening or closing stage of the group. The assembly constitutes substantially a three-way valve with complex components, while the pressure balance by gaskets disposed on stem 26 and 44 allows good performances, on the contrary the attainable flow rates are definitely reduced because of the small diameter of passages 50 and 48. The impossibility to operate under alternate current does not allow to meet the demand of a large portion of the market, due to lack of the phase displacement ring, together with the drilled duct 26 lightening the ferromagnetic material of the movable core 22, which in order to fall within the heating temperatures of the presently in force regulations, involves either a power reduction or an increase of the coil dimensions.

Finally document DE 9202519 discloses a normally open direct command two- way valve having the object of depressurizing substantially the main body so as not to cause the piston effect due to the tightness of gasket 14 on stem 5. This valve allows pressure balance only in the opening stage, since it does not have elements to balance pressure in the closure stage. This allows high performances by maintaining high flow rates, but to obtain a correct closure said valve requires a large increase of the spring elastic constant with a consequent increase of the coil power and related difficulty not to exceed the heating temperatures of the current regulations, obliging to make a coil of greater dimensions.

The above mentioned problems, were solved by a solenoid valve with balancing rod disclosed by the same Applicant in a preceding Italian patent application MI2012A000379 (now patent IT 1410423), in which a direct command solenoid valve is disclosed, that can work under conditions of high maximum pressures and high flow rates, because the pressure balance generated at closed valve allows to have a thrust area on which an almost null pressure is acting, that is important to increase the valve working pressures. It is to be noted that said valve was advantageously adapted to work with coils under direct or alternate voltage, that is under direct or alternate current, this factor being much demanded by users as the alternate current is the most used for innumerable applications.

Said solenoid valve may also be advantageously configured as either normally closed or normally open. An object of said prior disclosure was to make a direct command normally open solenoid valve, adapted to operate under both compression and traction. Moreover said valve is a direct command that may be used to control any kind of fluids such as liquids, gases, steam and even in any environment, such as the alimentary field, including also potentially explosive environments (when provided with a suitable protection cap). Said solenoid valve according to the above mentioned prior disclosure, comprises a balancing rod and passages between chambers and discharge ducts not requiring now a detailed description, as they were already illustrated adequately in the above cited prior disclosure.

Upon implementation of the above cited innovative solenoid valve with balancing rod, although the technical problem was solved by its innovative solution, Applicant found that such a solenoid valve comprised a considerable number of components, leading to a not negligible assembling difficulty, both for a correct positioning of the components and for the assembling time required. Moreover both quantity and type of said components for manufacturing these innovative solenoid valves, though achieving good performances, are definitely expensive.

Moreover, in view of the complexity and interaction of the parts, it was particularly difficult and challenging to make different kinds of passages and orifices for the fluids, so that the number of possible variations for flow rates, powers, diameters and the like is rather small, to the detriment of versatility of use and implementation according to the customer's requirements. One of the aspects aggravating the range of components consists of the side channels of connection between the upper and lower chamber and the discharge duct; although these channels are particularly innovative and advantageous, they oblige to use a number of gaskets and other contrivances to obtain the best tightness, leading to the above mentioned limitations.

More particularly, an object of the present invention in to optimize the production cost of the innovative solenoid valve, briefly described hereinbefore.

Another object of the present invention is to make a solenoid valve with balancing rod with high possibility of implementing numerous dimensions and flow rates, which can then be easily adapted to the installation requirements.

Still an object of the present invention is to keep the advantages of the solenoid valve proposed in the preceding invention together with the reduction of costs of its variations.

At last, another object of the present invention, together with said reduction of costs, is to achieve an optimization of the variations and versatility of use for various types of applications of the solenoid valve according to the present invention.

These and other objects will be obtained by the normally closed or normally open direct command solenoid valve with balancing rod, comprising a main body provided with a suction duct and a discharge duct for the fluid, a system consisting of movable core/fixed core/coil comprising a balancing rod and gaskets for sliding and sealing said balancing rod.

The present invention advantageously describes a normally closed or normally open direct command solenoid valve, comprising at least a main body provided with at least a fluid suction duct and a fluid discharge duct, an orifice between said suction and discharge ducts, a shutter for said orifice, an elongated command member having a first end connected to said shutter, and again a further elongated balancing member having a first end connected to said shutter and a second end sealingly sliding in a passage made in said main body with axis parallel to the orifice axis, said command member being provided with an internal discharge channel to allow passage of said fluid and contain leakage.

Therefore in the innovative invention that is being here illustrated, the discharge channels previously provided were removed from their preceding position, in a particularly advantageous and inventive way, thus allowing to reduce and transfer the number of components required to make the solenoid valve with balancing rod having the above mentioned advantages. More particularly, this ingenious modification allows to keep the advantages obtained by the previous invention considered as the closest prior art for the present invention.

In a still more advantageous way, the implementation of said discharge channel inside the movable core and balancing rod, allows to transfer some gaskets and in this way to eliminate advantageously several components. The elimination of said components, that will be described in detail hereinafter and in the annexed drawings, allows to reduce considerably costs besides simplifying the valve assembling operation.

Moreover, the provision of the discharge channel inside the movable core and balancing rod warrants in a substantially safe way, that the liquid flow does not leak out of said channel, so that this valve in a particularly advantageous way, may be used even in potentially explosive environments, without requiring addition of a special cap to hold possible leakage.

With regard now to the scarce versatility of adjustment of flow rates, dimensions of orifices and so on, this technical problem is overcome through variation of components and the provision of the central channel. There components in a particularly advantageous way, by variation of the diameter of the balancing rod, thanks to the contributions of several factors to be described hereinafter, allow to modify pressures and flow rates with great versatility and adaption to the user's requirements, still keeping the standard molds and varying only some simple working features. As to the further advantages obtained by the previous invention of the same Applicant, cited as prior art closest to the present invention, the advantageous features of the previously described solenoid valve are clearly maintained, obviously except those features that are described hereinafter as improved.

These and other advantages obtained through the solenoid valve with balancing rod described in the present invention, with related technical and economic advantages, will become apparent from the following detailed description of an illustrative preferred embodiment shown in the accompanying drawings, in which:

Figs. 1a and 1 b are cross-sectional views of the prior art solenoid valve corresponding to the above mentioned previous invention of the same Applicant; and

Figs. 2a, 2b are exemplary cross-sectional views of a preferred embodiment of the innovative solenoid valve with balancing rod according to the present invention.

With reference now to the drawings, Figs. 1a and 1 b show a preferred embodiment of the previous innovative solenoid valve with balancing rod of the same Applicant, wherein Fig. 1a is a cross-sectional view of a first preferred embodiment of a normally closed direct command solenoid valve shown in the condition of de-energized coil, i.e. of closure, and Fig. 1 b is a cross-sectional view of the solenoid valve of Fig. 1a shown in the condition of energized coil, i.e. open. One can see a main body 10 provided with fluid inlet duct 12 and an outlet duct 14 in communication through an orifice 15 having an axis orthogonal to the axes of ducts 12 and 14. The main body 10 also comprises a first upper chamber 16 and a second lower chamber 18. These chambers may be connected with a sleeve 40 and a plug 50, respectively, through threaded couplings where seats are provided for gaskets 42 and 52, respectively. More particularly the lower chamber 18 is in communication with the outlet duct 14 through a hole 17, while the upper chamber 16 is provided with a sealing member 20 fixed by interference fit. An outer gasket 26 is interposed between the outer wall of sealing member 20 and the inner wall of body 10. One can see that chamber 16 is divided by said sealing member 20 in a first zone 16a including orifice 15 and a second zone 16b facing the sleeve 40. In detail member 20 has a central hole 21 and a hollow disc 22. A movable core 38 sliding in sleeve 40 is arranged so as to pass through said hole 21 and said disc 22; a gasket 24 is disposed under disc 22 so as to be permanently in contact with the movable core 38. The upper end of this core has a seat for a spring, in its turn in contact with a fixed core 46 fastened on top of sleeve 40. Said sleeve is then inserted in a coil 44 so as to be influenced by the magnetic field generated by the coil on the basis of external signals. The lower end of the movable core 38 may be coupled, through threads or other fastening means, with the upper end of a balancing rod 32: a hollow shutter 30 is interposed between the lower end of movable core 38 and the upper end of the balancing rod 32 and remains clamped therebetween by screwing said ends. The lower end of the balancing rod 32 is so dimensioned as to slidingly close the lower hole 17: a hollow disc 34 and a gasket 36 assure that the flow does not flood directly chamber 18 thus aiding the pressure balance of rod 32 with the movable core 38, and at the same time allow the lower end of the balancing rod 32 to slide. Upper 11 and lower 13 discharge channels are also made in the main body 10 in order to communicate chamber 16 and chamber 18, respectively, with the discharge duct 14.

From the above description it is possible to note that the direct command solenoid valve according to the previously made invention, fully attains the previously mentioned objects. In the condition of de-energized coil 44, action of spring 48 forces downwards the movable core 38 and therefore shutter 30 against orifice 15: this prevents passage of fluid from inlet or suction duct 12 to the discharge or delivery duct 14; in this condition on the upper area of shutter 30, also the fluid pressure is acting. On this side of the discharge duct 14 different conditions are possible: the less onerous one in which at closed orifice the fluid is totally discharged with consequent null pressure, and the more onerous one where a pressurized tank is connected without interposition of valves and the like. Let us consider the latter condition with the obvious provision that the tank pressure is anyway below the delivery pressure of the solenoid valve. In the closure condition the discharge pressure then acts on the lower area of shutter 30 but also on the area of lower end of the balancing rod, with the resulting effect that may be reasonably approximated as null. In conclusion in order to switch the condition of the solenoid valve from closure to opening, it is necessary that the coil generates a magnetic force sufficient to overcome the elastic resistance of the spring and the feeding pressure, which however acts on an area of shutter 30 reduced by the dimensions of the diameter of the movable core 38. Therefore it is apparent that even increasing the maximum pressure and/or flow rate, through the diameter of orifice 15 and shutter 30, the power absorbed by the coil will be always limited.

It is also to be pointed out that sliding of the movable core 38 in disc 22 causes its deformation, with a concavity depending upon the sliding direction of core 38, and therefore, notwithstanding the presence of gasket 24, after a number of opening and closing cycles, leaks of fluid may occur at the zone 16b of chamber 16. In a similar way, leaks may occur from the discharge duct 14 to the lower chamber 18, caused by the sliding lower end of balancing rod 32 in the hollow disc 34. However the presence of the upper 11 and lower 13 discharge channels allow emptying of both the zone 16b and the chamber 18 while cycles are repeated. Motion of fluid in the discharge channel 14 indeed causes naturally a depression that actually sucks the leaked fluid, conveying it into the discharge channel 14.

As already mentioned, such a valve may be either normally closed or normally open, and this is a very advantageous characteristic which is an object of the present invention, as well as the operation with different modes of feeding voltage, but in a still more advantageous and inventive way, as above said, the present invention has and fulfils the object of solving the problems widely discussed above of said solenoid valve with balancing rod.

Therefore with particular reference to Figures 2a and 2b, for comparison purposes a preferred embodiment of the solenoid valve 100 is shown, with balancing rod according to the present invention, wherein Fig. 2 is a cross-sectional view of a first preferred embodiment of a normally closed direct command solenoid valve 100 in the condition of de-energized coil, and Fig. 2b is a cross-sectional view of the solenoid valve of Fig. 2a in the condition of energized coil; more particularly it is apparent that operation and components of the solenoid valve according to the present invention, being a particularly innovative and inventive revised improvement of the above described prior art, are substantially similar in order to make easier the recognition of the implemented innovations. More particularly, in a very inventive and advantageous way, the gasket or O-ring 24 and the relevant seat are arranged differently on the sleeve 40, so for sake of clarity said O-ring or gasket will be referenced as 24', thus allowing to eliminate the sealing member 20, gasket 26 and disc 22. The discharge channels 11 and 13 are no more present. It is to be noted that, although they were useful for accomplishing the above mentioned innovative technical advantages, said channels 11 , 13 involved the presence of gaskets, disc and sealing members, causing the above cited technical drawbacks that should be removed by the present invention. Indeed in a particularly advantageous way, by providing a passage or discharge channel 101 (replacing in a particularly inventive way said discharge channels 11 and 13, obtaining also surprising advantageous effects) inside the movable core 38 and balancing rod 32, it is possible to reduce possible leaks from O-rings 24 and 36 due to wear inside the outlet duct 14, by means of discharge channel or passage 102 made in the balancing rod 32 to connect the central discharge channel 101 with said outlet duct 14. In a particularly advantageous way it is therefore apparent that this invention allows to keep the innovative characteristics of the solenoid valve with balancing rod previously invented by the same Applicant, but in a still more advantageous way it allows to eliminate a plurality of components, thus reducing considerably the manufacturing and assembling costs of said valve. Moreover, it is possible to use these innovative valves even in potentially explosive environments without requiring covering elements, thus achieving a less cumbersome, more economic, reliable and versatile device.

Moreover these improvements contribute in a further advantageous way to simplify the valve, which may be made in a very versatile way. Indeed the different arrangement of the above mentioned parts allows to obtain a movable core 38 having a lower end 38a with an area greater than the upper end 38b, so that it is possible to maintain a single movable core 38, shutter 30 and main body 10 for any type of duct 12 and 14. Then it is possible to vary and set the desired flow rate rate by changing the intermediate diameter D of the balancing rod 32. With reference to Figs. 2a and 2b it is clear that in the opened and closed stage of solenoid valve, the above described operative conditions occur.

The solenoid valve 100 implemented according to the present invention may be easily adapted in the implementation stage to the customer's requirements and may be made according to specific needs without particular limitations.

It is also to be pointed out that elimination of the components sealing member 20, outer gasket 26 and hollow disc 22, as well as the different arrangement of the further sealing member 24, that in the new position is referenced as 24', simplifies considerably the assembling operations, since an expert in this field will note that in this way advantageously the flattening and riveting steps, generally required by rigid components like the sealing member 20 and disc 22, are eliminated. Moreover, in a particularly advantageous way, elimination of holes 11 and 13 allows to transfer the gasket 24 from the sealing member 20 to the sleeve 40; this allows to increase the diameter of gasket 24 and consequently also of the orifice 15, allowing to keep the pressure balance required for the operative principle defined as particularly relevant for the object of the present invention, which is indeed to keep said innovative principle by improving versatility, functionality and reliability of the valve as widely stated in the foregoing. It is also important that increase of the gasket diameter allows to widen the range of flow rates, keeping the same components adequately modified (movable core 38, sleeve 40, shutter 30 and main body 10) and to modify rod 32 preferably acting on variation of diameter D, but with possibility of varying said rod 32 also in other ways useful for the object of the present invention.

Therefore it appears substantially apparent that the innovations made to the solenoid valve with balancing rod described in a previous version of the same Applicant, though inventive was further improved in a particularly advantageous way, solving some not trivial technical problems, thus making the invention still more innovative, adding several technical advantages, such as more particularly lower manufacturing and assembling costs, in view of the smaller quantity of components. Assembly is also much quicker, with further reduction of production costs, and there is a greater standardization of the components, with an obvious additional reduction of costs. Moreover, the possibility of increasing and/or reducing the central diameter of the balancing rod, allows to vary the flow rate with great precision and make the valve particularly adapted to any situation, still maintaining the cost reduction and increasing the application fields and consequently the possible commercial exploitation.

In any case it is apparent that modifications to the present embodiment of the invention concerning a versatile and advantageous solenoid valve with balancing rod that may be normally closed or normally open, may be operated under conditions of maximum pressures and high flow rates, and may be implemented substantially at will according to the requirements of the intended use, are in any case falling within the scope of protection of the present invention. The holes 11 , 13 practically eliminated and transferred in an advantageous and inventive way to the central discharge duct 101 , allow to reduce adjustments and/or rectifications on machine tools, since the components do not require additional machining.

Moreover said solenoid valve with balancing rod combines the advantages of normal solenoid valves with cover for explosive environments and those of equal safety but little dimensions of this solenoid valve with innovative balancing rod. However even another further advantageous variation, being still cheaper, falls within the scope of protection of the present invention and may be considered an alternative embodiment: in such a case the balancing rod and the core may not be provided with holes, with relevant further reduction of costs, the same components sealing members 20, outer gasket 26 and hollow disc 22 are eliminated, but a discharge channel in the movable core and balancing rod is not provided; in this way there is still the advantage of reduction of components, but there is a risk of leakage of the contained liquid, so that this simplified solution is adapted only for non explosive environments, when a further reduction of costs is required.

The foregoing are only some of the preferred and possible embodiments of the solenoid valve with balancing rod and central discharge channel according to the present invention, and additional variations in which the elements of the system are combined in different ways, by opposition, engagement, joint of the elements acting as lever, fulcrum, fulcrum axes, or insulating elements such as O-rings and the like may have alternative forms or positions, as well as the balancing rod may also have alternative forms, but in any case adapted for the object of the present invention, as well as materials of any kind, or every modification that may in any case fall within the described object of the present invention, should be considered embodiments alternative to the previously described preferred ones, wherein modifications and changes for instance concerning the geometries chosen for each movable or fixed element, the materials adopted for each component, and even the specification of the operative system, may be resorted to, without departing however from the scope of protection of the present invention as defined in the appended claims.

Claims

1. A solenoid valve (100) with direct command normally closed or normally open, adapted to work under direct and alternate current, comprising a main body (10), with an inlet channel (12) for a fluid, an outlet channel (14) for discharging of said fluid, an orifice (15) between said inlet and outlet channels, a shutter (30) of said orifice (15), a movable elongated core (38) having a first end connected to said shutter (30), and a further elongated balancing rod (32), having a first end connected to said shutter (30) and a second end, sliding in a sealed manner, in a passage (17) formed in said main body (10) and having the axis parallel to the axis of said orifice (15), further comprising at least sealing gaskets (24) between said movable core (38) and a sealing member (20) and gaskets (26) between said member (20) and a sleeve (40), characterized in that said gaskets (24, 26) comprise a gasket (24') disposed directly between said sleeve (40) and said movable core (38), to increase the dimensions of the orifice (15) and consequently the valve flow rate, said movable core (38) and said balancing rod (32) comprise at least one discharging channel (101 ) for interconnection between said movable core (38) and said balancing rod (32), equipped with at least one passage (102), for connecting said at least one discharge channel (101 ) with said outlet channel (14), to maintain the pressure balance in said valve (100) and limit fluid losses.

2. The solenoid valve (100) with direct command according to claim 1 , wherein the gasket (24) of said valve and its seat are placed on the sleeve (40).

3. The solenoid valve (100) with direct command according to the preceding claims, wherein said movable core (38) comprises a lower end (38a) with an area that is greater than the one of the upper end (38b) of said movable core.

4. The solenoid valve (100) with direct command according to claim 3, wherein said movable core (38), the shutter (30) and the main body (10) are adaptable to any kind of channels (12) (14).

5. The solenoid valve (100) with direct command according to claim 3 and 4, wherein said balancing rod (32) has diameter (D) of its intermediate part (103), that is designed variable depending on the desired pressures.

6. The solenoid valve (100) with direct command according to claim 3 and 4, wherein said balancing rod (32) has diameter (D) of its intermediate part (103) that is designed variable depending on the desired flow rates.

7. The solenoid valve (100) with direct command according to claim 2, wherein said gasket (24) has a diameter compatible with the diameter of the orifice (15) to maintain the pressure balance.

8. The solenoid valve (100) with direct command according to claim 2 suitable for use in explosive environments.