MXPA97002376A - Hidraul solenoid control valve - Google Patents

Abstract

The present invention relates to a solenoid controlled valve for regulating the flow of a hydraulic fluid having an electromagnetic coil surrounding a ferromagnetic armature having the first and second axial ends and the first and second pole pieces at the opposite axial ends of the coil The shower valve comprises: a non-magnetic bearing slidably engaged with the first axial end of said armature so that the armature is free to reciprocally move therethrough, means for retaining the second axial end of said armature on the second part of said armature. pole to avoid the radial displacements of said armature and, an alignment sleeve having the first and second axially opposite ends, the first end of said sleeve is fixedly attached to the second pole piece so that the second end of the armature is virtually coaxial with the same, the second end of said sleeve is coupled coaxially and fixedly to said non-magnetic bearing

Description

HYDRAULIC SOLENOID CONTROL VALVE FIELD OF THE INVENTION The present invention relates to control valves operated by solenoid, and particularly to such valves having application with lubricating hydraulic fluids in hydro-mechanical apparatus such as automatic transmissions for motor vehicle.

BACKGROUND OF THE INVENTION Electromechanical solenoid operated control valves are widely used in the area of electronically controlled automatic transmissions. Two general types of such control valves include the pulse width modulated control valves (P M) and the linear control valves. Both types respond to a quantity of control, typically a voltage that varies with time, to control the line pressure, the pressure of the clutch chamber or the pilot pressure on the spool valve. It is generally understood that PWM valves have an armature that sticks between the first and second positions virtually at a frequency of correspondence with a voltage signal that varies with time while a linear control valve has an armature which assumes a position of balance according to the electromagnetic force generated by the average current through the solenoid coil and the internal pressure spring and the hydraulic forces.

PMW valves tend to be characterized by relatively large oscillations in control pressure in relatively low hydraulic situations such as when a complete control chamber of a clutch pack is supplied. This feature can be somewhat attenuated by increasing the frequency of the PMW; however, the upper PMW frequency is limited by the pull and the solenoid and armature drop times.

Linear control valves tend to be characterized by a smaller variation in control pressure since the armature is not moving from stop to stop during each PMW cycle while using higher PMW operating frequencies. Linear control valves are generally operated by an amount of tremor in the current through the solenoid coil to effect a mechanical analog on the armature which exchanges control pressure variation for hysterical operation. In PMW applications, tremor is essentially a function of the impedance characteristics of the solenoid coil and the PWM frequency of the drive signal. Everything else being equal, the PWM frequency increases tend to increase the hysteresis and require the reduction in the armor friction forces.

It is well known that hydraulic contaminants, from such varied sources as manufacturing and assembly operations as well as wear, fluid filling, etc. They can occur and can actually increase during the operational life of an automotive transmission. Particularly annoying contaminants for electronically controlled transmissions are ferrous materials which have a tendency to migrate to magnetic structures (for example to solenoid operated valves) when they are carried by circulating hydraulic fluid. Such contamination can result in undesirable increases in the armor friction forces and in a potential binding of the armature. With more and more transmission components being manufactured with the powdered metal manufacturing processes, the potential for increased levels of ferrous contamination of hydraulic fluid can be increased both in the infancy of the transmission and later during the operational life.

SYNTHESIS OF THE INVENTION Therefore, it is an object of the present invention to improve the operating characteristics of the solenoid valves.

According to one aspect of the present invention, the improved alignment of the valve armature along its stroke axis provides reductions in armor forces.

According to another aspect of the present invention, the contaminating infusion around the armature is reduced.

These and other aspects of the invention are provided in a solenoid valve having an electromagnetic coil surrounding a ferromagnetic armature. The armature has the first and second shaft ends and the magnetic parts of the solenoid include the first and second pole pieces at the opposite axial ends of the coil. The armature is secured to one of the pole pieces so that radial movement is prevented but nevertheless it is sufficiently free to reciprocate axially. An alignment tube surrounds the armature and is secured at one end of the pole piece to which the armature is secured. At the axially opposite end of the alignment tube is secured a non-magnetic bearing which surrounds the other end of the armature so that the armature is free to move reciprocably therethrough. The non-magnetic bearing may be coupled to the pole piece opposite the pole piece to which the armature is coupled as long as the clamp does not perturb the coaxiality of the bearing and sleeve. The sleeve additionally provides a recess of armor which is sealed from the infusion of the contaminating hydraulic fluid.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described by way of example, with reference to the accompanying drawing, in which Figure 1 is a sectional view of a linear solenoid valve according to the present invention.

DESCRIPTION OF THE PREFERRED MODALITY Referring to the figure, a linear solenoid valve of example 10 has an electromechanical part generally designated with the number 15 and a hydraulic part generally designated with the number 20. The hydraulic part 20 comprises a fluid conduit box 51 including the inlet of fluid 53, chamber 55, vertical movement valve seat 59 and fluid exhaust conduits 57. Vertical movement valve 43, which is dispersible between an accepted position against the vertical movement valve seat 59 as illustrated and a completely unaccepted position provides bleeding of the variable fluid from the fluid inlet 53 to the exhaust conduits 57. The aspects of the fluidic operation are generally well known to those skilled in the art and an additional discussion thereof. it is not necessary for a complete understanding of the invention.

The electromechanical part 15 of the solenoid valve is generally constructed with an electric coil 21 surrounding an armature 41 made of a ferromagnetic material. The coil 21 is conventionally wrapped around a non-magnetic reel 22 as illustrated. The spool 22 is preferably molded with an integral connector body 75. The ferromagnetic pole pieces, generally designated 31 and 34, are located on one side of the spool 21 at the opposite axial ends thereof. Each pole piece 31 and 34 has a respective substantially annular portion 32 and 33, extending radially beyond the outer circumference of the coil 21. The pole piece 34 has a central opening defined by the annular portion 33 and preferably continuous generally within the inner side wall of the spool to define an axially extending cylindrical portion 35 with a similarly sized bore. The pore piece 31 also has a central opening defined by an annular portion 32 and an axially extending cylindrical portion 37. As illustrated in the figure, the annular portion 32 of the pole piece 31 is abbreviated peripherally in the area of the connector body 75 in order to accommodate the externalization of the electrical interface. The ferromagnetic sleeve 13 virtually surrounds the coil 21 and the spool 22 and extends axially between the pole pieces 31 and 34 at the outer peripheries of the respective annular portions 32 and 33. Of course, the accommodation of the connector body precludes a complete closure of the coil and the spool at least in the generally limited area of the same.

The armature 41 is located virtually coaxial with the opening through the annular portion 33 of the pole piece 34 so that it is spaced adjacent to the cylindrical portion 35 of the pole piece 34. This is a relationship positional without bearing and is provided for a radially non-compliant member 65 which extends radially from the frame to a part of the pole piece 34. Preferably, the member 65 takes the form of a diaphragm spring formed of long stainless steel. life, an example of this being the 7C27M02 stainless steel material available from Sandvik, Inc., of Fair Lawn, New Jersey. In the present embodiment the armature 14 is characterized by several sections or steps of progressively smaller diameter which provide convenient mounting provisions for impaling the member 65 therein. Similar steps are provided analogously to the outer periphery of the annular portion 33 of the pole piece 34 which similarly provides convenient mounting provisions for the outer periphery of the member 65. A flexible seal 63 is similarly located between the armature 41 and the pole piece 34. The seal 63 similarly sits on the respective stepped portions of the armature 41 and the annular part 33 of the pole piece 34. The hydraulic part 20 of the solenoid valve 10 lies against from the outer periphery of the member 65 in an outer lip or eyebrow 51. The frame 23 is rolled or crimped onto the annular portion 32 of the pole piece 31 to retain the structures described.

At the axial end of the armature 41 closest to the pole piece 34 is the vertical movement valve 43 which is preferably a separately manufactured part and press fit into or otherwise secured in the armature 41. This assembly It is manufactured to strict dimensional tolerances to be able to establish the overlap of the armature 41 with respect to the pole piece 31 specifically the cylindrical part 37. By running the axial length of the armature 41 are a plurality of channels 47 for relieving and equalizing the fluid pressures inside the armor cavity. While it is generally undesirable to allow the infusion of hydraulic fluid into the armature cavity while in operation, a small amount thereof or a compatible virgin fluid is placed there during assembly for the lubrication of the armature. and of the bearing 61 as described below. The other axial end of the armature 41 has an orifice defined by the tapered side wall 45. Located inside the orifice and communicating with the base thereof is a pressure spring 27. The tapered side wall feature prevents the spring 27 from bending within the hole and contributes to the general desirable magnetic characteristics of such a linear device. The opposite end of the spring 27 lies against the threaded screw 19 inside the ferromagnetic ring 17. The ring 17 in turn can be joined to a cylindrical part 18 of the pole piece 31 by the threads or press fit there. Alternatively, the ring 17 can be formed integrally with the pole piece 31. Although described separately, the ring 17 and the screw 19 are considered to be parts of the pole piece 31. The screw 19 provides a range of adjustment to the force of spring pressure. The ring 17 is virtually aligned with the end portion of the tapered wall 45 of the armature 41. The flow therebetween generally provides an increased axial motive of force at higher flow levels as the armature is incrementally scattered to the left in the figure. When the frame is in the full right position, as illustrated, however, most of the axial motive force is printed through the flow between the tapered side wall and the cylindrical part of the pole piece 31. separation between the ring 17 and the armature 41 is set to establish the desired force against the displacement characteristics of the solenoid valve in a manner familiar to those skilled in the art. Therefore, the depth of the insertion of the ring 17 into the cylindrical part 18 was determined by the desired performance characteristics of the particular application. The pole piece 31 generally closes the respective end of the solenoid as it is put in a function of positioning the ring 17 and the screw 19. When the additional feature of spring pressure force adjustability is not desired, the cylindrical part 18 can be removed and the pole piece 31 formed without central opening therethrough.

The axial end of the armature 41 closest to the part 31 is slidably disposed through a non-magnetic bearing 61. Preferably the non-magnetic stainless steel is used for the bearing 61 since such material provides thermal expansion characteristics similar to those of the ferromagnetic material of the cylindrical part 37 of the pole piece 31 and has cycle wear qualities providing a long life. The bearing 61 is fixedly fixed to the cylindrical part 37 of a pole piece 31 by pressure adjustment of a cylindrical extension thereof to the inner surface of the cylindrical part 37 of the pole piece 31. It is critical for the operation of the High frequency PWM, that the current bearing surface, this is the inner surface of the bearing 61, has a virtually smooth surface finish. A surface roughness of virtually 0.5μm using stainless steel was found to provide acceptable performance at PWM frequencies of virtually 600Hz. The positional tolerances of the bearing are also strictly controlled to facilitate a smooth piston movement of the armature along an axis which is coaxial with the armature shaft. Therefore, the alignment sleeve 71 is adjusted with pressure at one end thereof on the bearing 61 of the pole piece 31. The axially opposite end of the alignment sleeve is similarly adjusted with pressure on the cylindrical part 35 of the work piece. pole 34. The arrangement as described provides the desired coaxiality between the piston movement of the armature 41 and the bearing 61. It has been noted here, however, that the outer diameter of the bearing 61 is larger than the outer diameter of the part cylindrical 37 to prevent the roundness or non-concentricity of the cylindrical part 37 relative to the bearing 61 from negatively impacting the desirable position tolerance of the bearing. The arrangement described, particularly the assembly and alignment provisions of the cylindrical part 35 in relation to the alignment sleeve is preferred for its simplicity in assembly and robustness in the structure. The alternating assembly between the alignment sleeve and the pole piece 34 can be effected as long as of course the object of alignment of the bearing 61 at the distal end of the sleeve provides a piston movement of the armature which is coaxial with the physical main axis. .

The sleeve 71 is preferably formed of non-magnetic stainless steel which again provides the characteristics of thermal expansion that are desirably similar to those of its matching parts, and has the structural integrity to maintain dimensional stability throughout the manufacturing process. , in particular any pressure adjustment thereof to the cylindrical part 35 of the pole piece 34 and the bearing 61.

Advantageously, the alignment sleeve 71 provides a closure around the armature cavity to prevent infusion of contaminants, particularly ferrous particles. As previously mentioned, the frame 23 does not provide complete sealing of the enclosed structure of the solenoid valve due in part to the accommodation arrangements for the electrical connector body. As can be seen from the examination of Figure 1, the main infusion path of at least the most visibly direct path through which the connector body passes is removed by the alignment tube coupled between the pole piece 34 and the bearing 61 thus providing a virtually sealed armor cavity.

Although the invention has been described with respect to a preferred embodiment including a preferred linear control valve, such description is offered by way of example and is not intended to be taken in any way as limiting the scope of the invention which is defined by the attached clauses.

Claims (7)

R E I V I N D I C A C I O N S

1. - A valve controlled by solenoid to regulate the flow of a hydraulic fluid having an electromagnetic coil surrounding a ferromagnetic armature having the first and second axial ends and the first and second pole pieces at the opposite axial ends of the coil, said valve comprising: a non-magnetic bearing slidably engaged with the first axial end of said armature so that the armature is free to move reciprocably therethrough; means for retaining the second axial end of said reinforcement in the second pole piece to prevent radial displacements of said reinforcement and, an alignment sleeve having the first and second axially opposed ends, the first end of said sleeve being fixedly coupled to the second pole piece so that the second end of the frame is virtually coaxial with it, the second end of said sleeve it is coaxially and fixedly coupled to said non-magnetic bearing.

2. - The solenoid controlled valve as claimed in clause 1, characterized in that said non-magnetic bearing is fixedly fixed to the first pole piece so that the coaxiality of the non-magnetic bearing and the sleeve is undisturbed.

3. - The solenoid controlled valve as claimed in clause 2, characterized in that the coupling of said sleeve to the second pole piece and the coupling of the non-magnetic bearing to the first pole piece are effective to prevent infusion of the fluid hydraulic in the respective couplings.

4. - A solenoid controlled valve for regulating the flow of a hydraulic fluid having an electromechanical part including a ferromagnetic armature surrounded by coil having the first and second axial ends, and the first and second pole pieces at the axial ends of the coil, said Valve comprises: a non-magnetic bearing slidably engaged with the first axial end of said armature so that the armature is free to move reciprocably therethrough; a yielding member characterized by an axial docility and a radial non-compliance to secure the second axial end of said reinforcement to the second pole piece; said second pole piece has a cylindrical part extending axially coaxial with and spaced adjacent said armature, said cylindrical part extending towards the first pole piece; Y an alignment sleeve having the first and second axially opposite ends, the first end of said sleeve being coupled coaxially and fixably to the cylindrical part of said second pole piece, the second end of said sleeve being coupled coaxially and fixably to said bearing not magnetic

5. - The solenoid controlled valve as claimed in clause 4, characterized in that said non-magnetic bearing is coupled to said pole piece, the coupling of the non-magnetic bearing to the first pole piece and the coupling of the first end of the sleeve to the cylindrical part of said second pole piece being effective against the infusion of hydraulic fluid.

6. - A valve controlled by solenoid to regulate the flow of a hydraulic fluid and having an electromechanical part, including a coil surrounding a ferromagnetic armature having the first and second axial ends, and the first and second pole pieces at the opposite axial ends of the coil, said valve comprises: said second pole piece defines a central opening through which the second axial end of the reciprocal reinforcement; means retaining the second axial end of said armature in the second pole piece to prevent radial displacements of the armature so that the second end of the armature remains in a proximity spaced with the central opening; sealing means between the second axial end of the armature and the second pole piece; Y, an alignment sleeve having the first and second axially opposed ends, the first end of said sleeve being fixedly fixed to the second pole piece so that the second end of the armature is substantially coaxial with it, the second end of said sleeve it is coupled coaxially and fixably to a non-magnetic bearing slidably engaged with the first axial end of said armature so that the armature is free to move reciprocably through it at a substantial coaxiality therewith, the non-magnetic bearing can furthermore be coupled fixed to the first piece of pole.

7. - The solenoid controlled valve as claimed in clause 6, characterized in that said second pole piece includes a cylindrical part coaxial with the central opening and extending towards said first pole piece, said sleeve is fixedly attached to the second piece of pole around the cylindrical part of it. SUMMARY A hydraulic solenoid control valve that has the ability to operate at high pulse width modulation frequencies due to the alignment accuracy of the armature and the freedom of contamination. An alignment tube coupled to one end in a pole piece is coaxially aligned with the armature while a non-magnetic bearing coupled to the other end of the alignment tube also aligns coaxially with the armature. Infusion of fluid into the armor cavity is prevented by the alignment tube that surrounds the armature.