ES2285908A1 - Proportional valve for controlling air expansion comprises secondary control system comprising first spring between fixed and mobile cores and second spring between membrane support and reducing element - Google Patents

Abstract

Proportional valve for controlling air expansion, comprising an axially mobile core, a fixed core with a cavity for receiving the mobile core, and a solenoid, comprises a primary control system comprising a reducing element whose position can be controlled to displace the mobile core and a secondary control system comprising a first spring attached at one end to a screw in the fixed core and at the other end to a stud on the mobile core, and a second spring with one end in contact with a membrane support fixed to the mobile core and the other end in contact with the reducing element. A proportional valve for controlling air expansion, comprising an axially mobile core (1) that is connected to a pneumatic part of the valve and exerts a counterforce proportional to the target expansion value, a fixed core (5) with a cavity for receiving the mobile core, and a solenoid comprising an electric coil (2) and a magnetic field surrounding the mobile core, comprises a primary control system comprising a reducing element (14) whose position can be controlled to displace the mobile core and a secondary control system comprising a first helicoidal spring (19) attached at one end to a screw (21) in the fixed core and at the other end to a stud on the mobile core, and a second helicoidal spring (20) with one end in contact with a membrane support (27) fixed to the mobile core and the other end in contact with the reducing element.

Description

Proportional regulating solenoid valve air depression

Object of the invention

The present invention patent application Its purpose is to register a proportional solenoid valve air depression regulator that incorporates notable innovations and advantages over other valves with the same purpose.

Background of the invention

Proportional solenoid valves are known for the regulation of air depression constituted basically by a solenoid that effects a force proportionally to an electrical control signal (usually a voltage signal "duty cycle" type) and by a pneumatic connection linked to a mobile component of the solenoid that effects a force proportional contrary to the depression value that the valve loads, the depression value given by the valve being the result of this balance of power. The solenoid is usually formed by an electric winding and a magnetic circuit made of materials ferritic with a particular geometry in regard to the components of attraction that originates a force between them that is linearly proportional to the electrical signal given to the winding

Most automotive manufacturers that they use these solenoid valves for their applications, as per example, for application on a TGV controller (turbocharger variable geometry), an EGR controller (gas recirculation of exhaust) or a controller of various pneumatic actuators, come lately demanding that the valve incorporate its own system of atmospheric air filtration that absorbs in its operation, because in this way they achieve a significant saving on the cost total system

One of the main problems this has type of proportional valves is located in the regulation of depression value that regulates the valve. In the geometries classical magnetic circuits, to obtain characteristics linear force versus the electrical signal in a margin reduced career, which also aims to obtain a maximum force with the lowest volume / cost of the solenoid, the profiles of the force curves against the variation of the squint respond to a bell geometry where, with respect to a maximum force, there is a previous rising slope and a slope subsequent decrease. These curves are very sensitive to position of the air gap, and therefore, strength values vary substantially with respect to the position in measurements of few tenths of millimeter so that a regulation of the relative position of the two nuclei that define the air gap during the manufacture of the piece, it would be impossible to obtain a precise regulation field only by restriction of tolerances of the components.

Ideally, the field of work of these valves should be as close as possible to the maximum force in the area of the subsequent decreasing slope since it allows, for a part, achieve maximum energy efficiency of the solenoid without that the abrupt passage from one curve to another by the variation of a signal electric cause force peaks that subsequently move to unwanted pressure spikes, unlike if it happens if regulates on the increasing slope, in addition to the proximity to the maximum avoid having hysteresis in the curve at high duty cycles. This phenomenon begins to appear if it is regulated too far from the maximum on the decreasing slope because the lateral surfaces Faces of the cores are too large. Therefore, the precise air gap regulation is necessary not only for get an optimal strength value but also to reduce to maximum of the two problems mentioned above.

On the other hand, it should be considered that in the over time car manufacturers have perfected its systems and the degree of demand of the valves has increased, in particular, in terms of reducing the tolerance in the pressure characteristic that gives the piece, what which involves performing a second fine regulation of the valve to maximum focus on a particular point of the characteristic the pressure value regulated by the valve with respect to the nominal required.

Another inconvenience no less important than present this type of valves is that they can easily lose their provideability characteristic over time due to the accumulation of dirt inside, dirt that is absorbed  during the aspiration of the air from the atmosphere.

This dirt accumulates by two factors; one of them is the absorption of dust and the second is the absorption of water, so that the combination of both results in the formation of an initially viscous mass that, over time, leaves hardening until it blocks the mobile components of the valve and / or close the passage between the different chambers.

Valves of the type described here are described for example in German applications No. DE 4205565 and No. DE 19805417 that refer to pressure transducers electro-pneumatic for the control of the tires of a vehicle and that present the drawbacks described above.

Description of the invention

The present invention has been developed with the in order to provide a proportional regulating solenoid valve air depression that solves the problems above mentioned, contributing, in addition, other additional advantages that will be evident from the description that accompanies continuation.

It is the object of the present invention to provide a proportional air depression regulating solenoid valve that comprises in the solenoid zone a movable mobile core axially that effects a counter force proportional to the value of  default depression to load the valve, a fixed core does not adjustable at one end of the valve that has a cavity for the introduction of one end of the mobile core, a solenoid formed by an electric winding and a magnetic circuit linked to the mobile core in an enveloping manner.

There is a depression entrance that allows to communicate with an application camera, being able to the camera application in turn communicate with the pressure chamber atmospheric, an elastomeric membrane having been provided between the application chamber and atmospheric pressure chamber that allows The tightness of the two chambers.

The elastomeric membrane is associated indirectly to the mobile core through the presence of a support membrane. Said support has a lateral groove, arranged in the zone of contact with the elastomeric membrane, which facilitates the passage of a microfuge between the application chamber and the camera atmospheric minimizing hysteresis in the pressure curve at high duty cycles

On the other hand, the membrane support is constituted by a thermoplastic material resistant to temperatures higher than 200 ° C, said membrane support being fixed to the core mobile.

The valve is characterized by presenting means positioning for centering and alignment between the number fixed and the mobile core, said positioning means being formed by a magnetic bushing fixed by one of its ends to the fixed core by its outer face and being in contact with a ferritic component, and a sliding bushing inserted into the magnetic bushing on which the mobile core; and means of regulation for the adjustment of the curve of Pressure.

Thanks to these features, the centering and alignment of the two cores, reducing the possible problems caused by unwanted contacts between both cores during valve operation. It also facilitates assembly of the various components, minimizing the possible dimensional manufacturing defects and manufacturing costs of solenoid valves

The said regulation means for adjustment fine pressure curve are provided with a first spring coupled at one end to a projection protruding from a screw Adjustable non-magnetic material that is threaded to the fixed core and at its other end is coupled to a projection arranged in the mobile core, a second spring that is at one end in contact with the mobile core at the end opposite the end mentioned above and on the other end is associated with the reducing element In this way, the two springs work in opposition between them. By compressing the first spring by means of the adjustable screw can be achieved that the Valve pressure characteristic is increased or reduced regarding the characteristic previously defined with the regulation principal.

Additionally, the valve also includes regulating means for adjusting the pressure curve and a system for dust filtration and protection of Water.

Preferably, the sliding bushing It consists of a magnetic steel outer jacket and a inner face of polytetrafluoroethylene (PTFE). The presence of a PTFE layer provides a very low coefficient of friction and Reduces the wear of the parts involved in the movement.

To perform the main regulation, the solenoid valve includes a movable mobile reducing element axially to allow movement of the mobile core and regulate the position of the air gap between cores, being the position of said reducing element adjustable by a piece screwed, preferably of plastic material, which is fixed to the reducing element, having a threaded outer section that is threaded to a threaded section of a cover that has an inlet air coming from outside.

Advantageously, the piece of plastic material includes two elastomeric O-rings to perform the tightness between the depression chamber and the application chamber and between the depression chamber and the outside.

It is another object of the invention to provide a solenoid valve that includes a modular compensation device of temperature for solenoids. Said modular device comprises a housing that includes an electric conductive material track which protrude in the direction perpendicular to said track a plurality of fins acting as fixing means for be coupled to the housing and electrical connection means, a resistance whose resistance value does not vary with temperature and a resistance whose resistance value varies with temperature housed in the housing, being electrically connected to the track through a thread protruding from each of the resistors, and a second plurality of fins provided in the track of conductive material to connect to the terminals of a coil, having also provided an electrical termination linked to the track of conductive material to be coupled to a electrical terminal

According to another feature of the solenoid valve of the invention, comprises a system for dust filtering and for water protection characterized by the fact that it comprises a first filter element arranged at the air inlet and a second filter element arranged in a later section behind the solenoid, the air inlet and the aforementioned section connected through ducts, so that the air is passed through the first filter element and subsequently it is passed through the second filter element before Enter a chamber at atmospheric pressure.

Advantageously, the system for filtering comprises a deflector element of plastic material located in the air entrance. In this way, the direct entry of water is prevented by splash and also provides an area where the water accumulation that gets in.

According to another aspect of the invention, the second filter includes a protective cap to insulate it from the outside linked to the solenoid valve housing, thus guaranteeing water tightness.

In an alternative embodiment, the system for dust filtering and for water protection it can be constituted by a single filter arranged in the air inlet.

Other features and advantages of the Proportional solenoid valve regulating air depression object of the present invention will be apparent from the description of a preferred, but not exclusive, embodiment illustrates by way of non-limiting example in the drawings that are accompany, in which:

Brief description of the designs

Figure 1.- It is a cross-sectional view. of the proportional regulating valve of the present invention;

Figure 2.- It is a sectional view in plan of a lower section of the valve of figure 1 corresponding to a section where the filter elements are located;

Figure 3.- They are two explanatory graphs of the relationship between depression and electrical signal and, force and Electrical signal; Y

Figure 4.- It is a perspective view of the modular temperature compensation device for solenoids disposed at one end of the valve object of the invention.

Description of a preferred embodiment

As shown in Figure 1, the proportional air depression regulating solenoid valve The present invention is constituted by a solenoid that performs a force proportional to an electrical control signal and by a pneumatic part associated with a mobile core (1) of the solenoid that carries out a force contrary to the value of depression that loads the valve. The depression value that gives the Valve is the result of this balance of forces.

The solenoid is essentially formed by a electric winding (2) and a magnetic circuit composed of ferritic materials with a particular geometry in the attraction components, that is, the mobile core (1) and a core fixed (5), which causes a force between them that is linearly proportional to the electrical signal given to the winding.

In the pneumatic part there are two closures between chambers closed by a single elastomer element (3). One of the closures communicates the depression entrance (a) with the chamber of application (b) and the other closure communicates the application chamber (b) with the chamber at atmospheric pressure (c). Application cameras (b) and atmospheric pressure (c) are separated by a membrane elastomera (4).

The elastomeric membrane (4) is associated indirectly to the mobile core (1) by the presence of a membrane support (27). Said support has a lateral groove, arranged in the zone of contact with the elastomeric membrane (4), which  facilitates the passage of a microfuge between the application chamber (b) and the atmospheric chamber (c) minimizing hysteresis in the curve pressure at high duty cycles.

On the other hand, the membrane support (27) is constituted by a thermoplastic material resistant to temperatures above 200 ° C, said membrane support (27) being fixed to the mobile core (1).

The valve loads or discharges depression in the application chamber (b) opening one or the other of the closures between cameras depending on the balance of forces. If the force of solenoid is greater than the force originated on the membrane elastomera (4) due to the difference in pressure between chambers, the mobile core (1) approaches the fixed core (5), so that as drag with it the elastomer element (3) that closes the passage between the application chamber (b) and the atmospheric chamber (c) it allows the passage between the entrance of depression and the chamber of application (b) loading this depression until the balance of power.

If the solenoid force is less than force originated on the membrane (4) due to the difference in pressure between chambers, the mobile core (1) moves away from the fixed core (5), so that as the elastomer element (3) remains fixed resting on the closing of the reducing element (14) closing the passage the passage between the pressurized chamber opens in turn atmospheric (c) and the application chamber (b) discharging it from depression until you get the balance of forces.

To ensure that both in the movement of load as in the discharge of depression the elastomer element (3) make a correct closure on each of the two closures of step is mounted a helical spring (28) supported on one side on the elastomeric element (3) and on the other on a hole bottom made in the mobile core (1).

To ensure correct spring support helical (28), spring, on the elastomeric element (3) east it has a cylindrical external geometry on which it focuses the spring and prevents its lateral movement.

In order to prevent the entry of air and unwanted dust into the solenoid valve, includes a filtering system formed by a first filter element (6) arranged in the air inlet and a second filter element (7) arranged in a later section located behind the solenoid, the air inlet and said section being connected through inner lateral ducts that are made in the injected (8) of the winding, so that the air is passed through the first filter element (6) and subsequently passed through the second filter element (7) before entering a pressure chamber atmospheric (c). To facilitate understanding, Figure 3 shows find some arrows that indicate the direction of air.

The filtering system is completed by a baffle element (9) of plastic material located at the entrance of air and a protective cover (10) that includes the second element filter (7) to insulate it from the outside linked to the housing of The solenoid valve.

The solenoid valve also has means of positioning for centering and alignment between the core fixed (5) and the mobile core (1), said means being positioning formed by a magnetic bushing with wall (11) in which the sliding bushing (12) is inserted over the which internally slides the mobile core (1). The subset of bushings (11, 12) focuses on the fixed core (5) by appropriate tooling and fixed to the ferritic component which closes the magnetic circuit at the bottom by means of the laser welding union. The fixed core (5) is previously set to a washer (13) by nailing or riveting and then It is covered by the superinjected of the coil.

The valve also has means of regulation for the adjustment of the pressure curve.

The said regulation means for adjustment fine pressure curve are provided with a first spring helical (19) coupled at one end to an overhang of a regulating screw (21) advantageously of plastic material. Said screw (21) is threaded to the fixed core (5). For his other end the coil spring (19) is coupled to a shoulder arranged in the mobile core (1). A second helical spring (20) is at one end in contact with the mobile core (1) by the opposite end to the aforementioned end and on the other end is associated with the reducing element (14). Given the little thickness and considerable height, the reducing element (14) is manufactures with a metallic material. The screw (21) once adjusted it is fixed and sealed by plastic fusion welding with the overinjected of the coil thanks to an ideal geometry in both pieces. This ensures that the regulation does not change later.

On the other hand, the screw (21) has a cylindrical section adjusted to the diameter of the fixed core (5) that is positioned before the thread so that the screw (21) when begins to thread does not allow the introduction of particles towards the inside of the solenoid valve.

Since the core is fixed, the variation of the relative position of the air gap (H) between the fixed core (5) and the mobile core (1) is performed by varying the position of closing, that is, the displacement of the reducing element (14). Said reducing element (14) is regulated by a piece (15) that it has an external thread, said piece (15) moving with with respect to a thread made in a central turret of a lid pneumatic (16).

The piece (15), advantageously realized in plastic material, has a geometry in its lower part exterior suitable for fixing by welding plastic fusion with the pneumatic cover (16), also of material plastic, to ensure that once the valve is regulated in the process the part (15) cannot be moved later.

The pneumatic cover (16) and the injected (8) they are united in a solidary way by welding in plastic, of so that at a stage prior to final assembly both sets of Elements are separated.

The internal chamber of the part (15) is communicated through a through hole through the chamber of the entrance of depression (a). Said piece (15) has two elastomeric O-rings (17), (18) for sealing between the depression chamber (a) and the application chamber (b) and between the depression chamber (a) and the outside.

The piece (15) presents in the housing where the elastomeric O-ring (17) is mounted a section groove controlled that communicates the depression chamber with the application chamber allowing a microfuge between both cameras. This microfuge allows to have a small residual value of depression in the application with the valve without feeding which helps the valve start regulating depression at lower duty cycle values than without this microfuge with what you get to have a more linear depression characteristic across the entire range of functioning.

Mention that the sliding bushing (12) It consists of a magnetic steel outer jacket and a inner face of polytetrafluoroethylene (PTFE).

Another aspect to highlight is the presence of a modular temperature compensation device for solenoids arranged at one end of the solenoid valve, so that it allows constantly maintain the characteristic pressure curve, regardless of the winding thermal conditions.

Said modular temperature compensation device for solenoids (see Figure 4) comprises a housing (22) that includes a track (23) of electrically conductive material from which a plurality of fins acting as perpendicular to said track protrude. fixing means for coupling to the housing (22) and electrical connection means, a resistor (24) whose resistance value does not vary with temperature and a resistor (25) whose resistance value varies with the temperature housed in the housing ( 22), being electrically connected to the track through wires that protrude from each of the resistors, and a second plurality of fins (26) provided on the track (23) of conductive material to connect to the terminals of a coil , in addition to providing an electrical termination linked to the track of conductive material to be coupled to an electrical terminal
trico.

According to an alternative embodiment, no represented, the system for filtering dust and for water protection may consist of a single filter arranged in the air inlet.

The details, the shapes, the dimensions and other accessory elements, as well as the materials used in the manufacture of the proportional regulating solenoid valve air depression of the invention may conveniently be replaced by others that are technically equivalent and not depart from the essentiality of the invention or the defined scope by the claims included below.

Claims (11)

1. Proportional air depression regulating solenoid valve comprising a movable and axially adjustable movable core (1) that is linked to a pneumatic part of the solenoid valve, so that it exerts a force contrary to the value of depression that the valve loads, a non-adjustable fixed core (5) disposed at one end of the valve that has a cavity for the introduction of the attractive end of the mobile core (1), a solenoid formed by an electric winding (2) and a magnetic circuit linked to the mobile core ( 1) in an enveloping manner, characterized by the fact that: It comprises primary means of regulation, which regulate the relative position between the attractive nuclei (1, 5), comprising an axially movable reducing element (14) that allows the movement of the mobile core (1) with respect to the fixed core (5), the position of said reducing element (14) being adjustable; Y comprises secondary regulation means for the fine adjustment of the pressure curve that allows varying the pressure values, being provided with a first spring helical (19) coupled at one end to a screw type part (21) threaded at one end to the fixed core (5) and at the other end coupled to a projection arranged in the mobile core (1); Y a second helical spring (20) that is at one end supported on a membrane support (27), integral to the mobile core (1), and by the opposite end is resting on the reducing element (14). 2. The solenoid valve according to claim 1, characterized in that it comprises a part (15) integral with the reducing element (14) that has an orifice for screwing and regulation being properly coupled and fixed to a cover (16). 3. The solenoid valve according to claim 1, characterized in that the screw-type part (21) has at its upper end an orifice for screwing and regulation being properly coupled and fixed to an injected (8). 4. The solenoid valve according to claims 1 and 2, characterized in that the piece (15) of plastic material includes two elastomeric O-rings (17, 18) for sealing the depression inlet (a) and the chamber of application (b) and between the entrance of depression (a) and the outside. 5. The solenoid valve according to claim 1, characterized in that the membrane support (27) is constituted by a thermoplastic material resistant to temperatures above 200 ° C, said membrane support (22) being fixed to the mobile core (1). 6. The solenoid valve according to claim 1 and 5, characterized in that the membrane support (27) of the elastomeric membrane (4) has a lateral groove, arranged in the zone of contact with the elastomeric membrane (4), which facilitates the passage of a microfuge between the application chamber (b) and the atmospheric chamber (c). 7. The solenoid valve according to claim 1, characterized in that the cover (16) and the superinjected (8) are joined together by elastic fasteners and welding. 8. The solenoid valve according to claim 1, characterized in that the part (15) has a lateral groove of controlled section in the housing of the O-ring (17) that allows the passage of a microfuge between the depression chamber ( a) and the application chamber (b). 9. The solenoid valve according to claim 1, characterized in that it includes a modular temperature compensation device for solenoids. 10. The solenoid valve according to claim 9, characterized in that the modular device comprises a housing (22) that includes a track (23) of electrically conductive material from which a plurality of fins acting in said direction perpendicular to said track by way of fixing means to be coupled to the housing (22) and by way of electrical connection means to the electrical components that are constituted by a resistor (24) whose resistance value does not vary with the temperature and a resistance (25) whose resistance value varies with temperature, such resistances being housed in the housing (22), the electrical connection with the track being made by interference of the fins with a wires protruding from each of the resistances, and a second plurality of fins (26) provided on the track (23) with conductive material to connect to the terminals of a coil, having also provided a termination electrical linked to the track of conductive material to be coupled to an electrical terminal. 11. The solenoid valve according to claim 1, characterized in that it comprises a first filter element (6) disposed in said air inlet duct and a second filter element (7) arranged in a rear extension located behind the cylindrical section and which is aligned with respect to the air inlet duct, the air inlet duct and said extensions being connected through internal ducts located in the housing (22), so that the air initially passes through the first element of filter (6) and then it is passed through the second filter element (7) before entering inside the cylindrical section of the valve.