Patent Application
20130032742
The invention refers to a solenoid with a coil, a magnetic yoke, an armature housing, an armature supported movably in the armature housing, an armature spring and an adjustment pin that can be put in the magnetic yoke.
Solenoids of this kind are often part of a complex operating device. By means of the solenoid, different conditions of the operative device are set, for example a locking is generated or a pressure valve or pressure control valve is operated. The solenoid has a coil that can be supplied with current. When current flows through, the result is a magnetic field acting usually against the power of an (armature) spring on a magnetizable armature that is arranged movably in the armature housing of the solenoid. The armature moves depending on the resulting magnetic field.
So-called proportional magnets or proportional solenoids have been known as well, where the position of the armature (and thus also the position of the element moved by the armature) is proportional or largely proportional to the flow of current.
This results in a movement of the armature between two or more different positions. Generally, the armature acts on an operating element of the solenoid, for example an armature rod or the like. Depending on the arrangement, the operating element is here connected rigidly with the armature, or the armature acts in an appropriate way on a separate operating element, arranged movably in relation to the armature. This operating element can be used, for example, in a pressure control for operating locking elements provided therein, and for mutually connecting the respective feeds or returns or consumer connections to one another. Also the volume flow can be regulated thus.
What is decisive for the proper function and desired effect of the solenoid is the adjustment of a characteristic line. Adjusting the characteristic line is executed through an adjustment pin arranged in the solenoid. The adjustment pin is pressed in the magnet until the eventual adjustment of the desired characteristic line, and acts here as stop for the armature spring, that is supported on the adjustment pin, the spring acting on the armature. Depending on the penetration depth of the adjustment pin in the solenoid or the magnetic yoke provided therein, the spring is compressed and the armature position is adjusted, respectively. Through this, then the armature can be adjusted in the armature housing.
Usually, the adjustment pin is manufactured in a complex process. A cone is screwed on a grinded round rod, the area worked in this way is then cut off or parted from the grinded rod, and, after that, a backside bore hole is integrated in the separated section of the round rod. The procedure described before requires a multiple moving of the component to be worked, so that the manufacturing of the adjustment pin is particularly complex. The result is high costs for the adjustment pin, that is generally a mass product, as suitable solenoids cannot be produced without adjustment pins of this type.
It is an object of the present invention to improve the state of the art such that a solenoid can be produced with reduced effort and reduced costs.
In order to solve this problem, the invention refers to a solenoid as described in the beginning, and suggest that in the solenoid an adjustment pin is used that can be shaped by means of cold forming of solid material.
Based on the application, for example, of a cold massive forming process for manufacturing the adjustment pin, the before described single, expensive and complex steps for manufacturing the adjustment pin are substituted in conventional metal-cutting processes, and the adjustment pin can be manufactured in a single processing step. During the manufacturing process, a raw part is put in a tool suitable for forming, and is formed without the raw part being heated. Such a forming can be performed by pressing a tool into the raw part. Here in a (single) processing step the shoulder for supporting the armature spring, on the one hand, and the backside recess in the adjustment pin, on the other hand, can be formed. The material weakness or reduction of material thickness in the circumference area of the adjustment pin, that can also be accomplished by forming, eventually achieves the same result, as the boring employed in the conventional procedure.
The adjustment pin manufactured in the cold massive forming process thus can also be inserted in the press fit in a yoke or in another way in the solenoid, and is held in the press fit.
The invention also comprises the use of an adjustment pin manufactured in a cold forming process in a solenoid, in particular in a solenoid as described before. The dimensional accuracy of an adjustment pin manufactured by cold forming may be slightly less than by a metal-cutting machining, however, these increased dimension tolerances are compensated in the adjustment process of the characteristic line, that will take place in any case, as the position of the adjustment pin in the press fit is determined according to the course of the characteristic line and not according to the absolute position of the adjustment pin in the press fit. Surprisingly, therefore a simply manufactured, generally not highly accurate component does not lead the technical properties of the solenoid according to the invention to deteriorate, so that in particular the use according to the invention is advantageous.
It is an essential advantage of the invention that the adjustment pin can be provided economically. Furthermore, the use of a pressing tool for forming guarantees that the manufactured adjustment pins have always constant quality and dimensions.
Cleverly, the projection has a smaller diameter than the rest of the adjustment pin. Seen in direction of assembly, the projection is put in first in the opening or yoke or the solenoid forming the press fit, and the smaller diameter makes, of course, inserting the adjustment pin in the press fit easier.
The projection forms a mandrel on which the armature spring can be slid. The projection thus serves also for guiding and centering the armature spring.
A preferred embodiment provides between the cylindrical section and the projection a fitting shoulder, in particular for the armature spring. Cleverly, the projection is configured here as radially circulating annular surface, however, it can also be cone-like or inclined funnel-like.
It is an advantage that the shaping of the recess, the forming of the projection as well as of the fitting shoulder is performed in a single step of the cold forming, in particular relating to a raw part designed as section of a profile or rod. Clever configuration of the cold forming tool allows performing all necessary forming operations in the raw part in a single processing step, what saves time and costs.
Another improvement provides that between the projection and the cylindrical section, in particular between the fitting shoulder and the cylindrical section, in particular a cone is provided, that is integrated, preferably also during the single cold forming processing step, in the adjustment pin. The before mentioned cone precedes the cylindrical section in assembly direction, and thus makes inserting the cylindrical section in the press fit easier. The press fitting occurs in the cylindrical section and the (insertion) cone, arranged before in assembly direction, makes mounting easier.
The solenoid suggested according to the invention is employed preferably in a pressure control valve, and here in particular in a proportional pressure control valve. In a proportional pressure control valve, the pressure is related, at least in certain areas, in a proportional relation with a control value, for example current of the electricity flowing through the coil of the solenoid. Cleverly, therefore the solenoid is configured as proportional solenoid, and has, at least in sections, a corresponding proportionality or other course of the characteristic line, as desired. Just for being able to set this course of the characteristic line, the adjustment pin suggested according to the invention is provided.
The solenoid according to the invention is suited in particular for the use in a pressure control valve, also provided according to the invention. Here, the armature operated via the armature spring and the electro-magnetic electrification of the coil is connected with an activation rod that acts on the locking elements of the valve part and moves them from a first in a second locking position. The adjustment of the characteristic line of the pressure control valve is performed here through the adjustment pin, that is pushed, until the perfect characteristic line has been reached that is determined in a testing process, in the solenoid or the yoke bridging the solenoid. The armature spring is compressed, and thus the armature in the armature housing is shifted. This again can adjust the effect on the locking parts of the pressure control valve.
In this connection it is, in particular, pointed out that all characteristics and features described with reference to the solenoid, but also methods, can be transferred and used in a solenoid accordingly also with reference to the formulation of the use according to the invention of an adjustment pin, manufactured in a cold forming process, and are seen also as disclosed. The same goes also vice versa, that means constructive, i. e. device characteristics mentioned only with reference to the use, can also be considered and claimed in the frame of claims for the solenoid, and are also part of the invention and disclosure.
In the drawing the invention is shown schematically in particular in an example. In the FIGS.:
In the FIGS. identical or corresponding elements each are indicated by the same reference numbers, and therefore are, if not useful, not described anew.
When the coil 15 is supplied with current, the armature 17 is shifted against the spring power of the armature spring 26 in the armature housing 18. When the electrifying of the coil 15 ends, the armature spring 26 guides the armature 17 back in the starting position. The armature 17 has an activation rod 27 connected with the first locking part 28 of the valve part 11. In the embodiment of the pressure control valve 10 shown in
The medium flowing in the lower valve part 30 can only flow through bore holes 36 in a cage 44 linked below the first valve seat 35 in the opening 43 released by the locking part 28 lifted from the valve part. The pressure control valve works according to the pressure dividing principle, wherein the actual pressure control is performed at the first seat valve (formed by the first locking part 28 and the first valve part 35). The second (first with reference to the direction of medium flow) seat valve (formed by the second locking part 29 and the second valve seat 32) is opened.
Directly below the coil 15 the core 38 of the solenoid is joined having a passage bore hole 39 through which the activation rod 27 is guided. Between the lower end 40 of the armature facing the valve part 11 and the core 38, a working gap 41 exists in axial direction.
Another working gap 42 exists between the end of the armature 17 facing the yoke 21 and the yoke. In the non-electrified resting position of the magnetic part 12 this gap 42 is opened.
The armature spring 26 is supported, on the one hand, on a shoulder 25 provided at the adjustment pin 23, on the other hand, on the armature 17. For a more stable support of the armature spring 26, the adjustment pin 23 has a projecting nose or a projection 24 that is partly encircled by the windings of the armature spring 26. The second, free end of the armature spring 26 is supported on a supporting surface provided in the armature 17 thereon.
A suitable pressing tool serves for this. A punch acts here on the raw work piece in such a way that it is formed. The tool is here configured such that during forming the nose-like projection 24 is shaped in longitudinal direction (or in axial direction, defined by the center axis 54 of the adjustment pin 23 that is preferably essentially parallel to the direction of movement of the armature 17) in the raw part. The raw part is pressed for this by the punch of the pressing tool in a corresponding die. The center axis 54 is orientated parallel to the direction of movement of the armature 17 and the direction of movement of the adjustment pin 23 in the press fit 200. During forming, also the recess 50 is shaped in the adjustment pin 23. The recess 50 is here located on the side opposite the projection 24. The recess 50 extends at least in the cylindrical area 52 of the adjustment pin 23. At least some parts of the cylindrical area 52 form essentially the surface area of the adjustment pin 23 effecting a sufficiently mechanically solid connection in the recess 22 of the yoke 21 in the press fit 200.
Based on the reduction of the wall thickness d of the adjustment pin occurring in the area of the recess 50 during the cold forming, this part of the adjustment pin 23 can be formed to a limited degree what favors inserting in a corresponding recess 22 in the yoke 21 of a solenoid. The adjustment pin 23 can be held here in the press fit 200.
Additionally, the adjustment pin 23 has a fitting shoulder or shoulder 25 on which the armature spring 26 can be supported. The nose-like projection 24 or nipple projects here partly in the armature spring 26. This stabilizes the position of the armature spring 26 in the solenoid. The shoulder 25 is designed here as flange-like annular surface. It extends, seen in direction of the center axis 54 after the cylindrical area 52 and the insertion cone 53, before the projection 24. The conical shape of the nipple 24 is here a result of the tool used for manufacturing the adjustment pin 23. Besides the conical or truncated conical configuration presented here, there is, of course, also the option of designing the projection 24 or nipple in the way of a cylinder or also cone-like, ball-like or spherically (e. g. differing from a ball shape).
The recess 50 is not formed by metal-cutting, but by (cold) forming. It is configured in longitudinal direction of the center axis 54, preferably coaxially thereto, as pocket hole.
In the interior of the recess 50, on the bottom 55 of the pocket hole, a cone-like embossed stamp 51 can be discerned. This is also a result of the forming process. This indentation or depression serves also for receiving the tool that is used for inserting or impressing the adjustment pin 23 in the solenoid or its yoke 21. The indentation or depression prevents here effectively a sliding or shifting of the tool in the adjustment pin 23. As a rule, the tool has a diameter smaller than the diameter of the recess 50 in order to favor here the elastic forming of the adjustment pin 23 during the impressing process in the solenoid.
The interior walls or surface area 56 of the recess 50 can be weakened specifically in certain areas by the (cold) forming process, for example by a groove or flute extending parallel to the center axis 54, in order to configure thus the cylindrical section 52 “softer” for impressing in the press fit 200.
Inserting the adjustment pin 23 in the solenoid or in a recess 22 provided there is improved additionally by the conical tapering of the outside walls of the adjustment pin 23 in the area between the cylindrical section 52 and the shoulder 25. Based on the thus reduced diameter, the adjustment pin 23 can be inserted particularly easily in the recess 22. The chamfer or the cone 53 thus serves for guiding the adjustment pin 23. Its length changes because of the cold forming of a raw work piece. At the same time, the material thickness is increased in the area of the nipple 24 or the joining lower area of the adjustment pin 23.
The adjustment pin 23 shown in
Compared with the hot massive forming or a metal-cutting or milling machining of the adjustment pin 23, the form and dimensional accuracy of the cold formed adjustment pins 23 is essentially larger. There is no shrinkage during cooling. There are none or only little tolerances, compared with the metal-cutting machining with this type of material forming. As the material forming the adjustment pin 23 solidifies during pressing, when cold, in the cold massive forming, for example high alloy steels can be substituted by more economic materials.
The stress distribution in the adjustment pin 23 can be controlled easily because of the rotational symmetric shape. Based on the mere forming of the material, the result is, in contrast to metal-cutting processes employed conventionally for manufacturing the adjustment pin 23, a rather high saving of material and, additionally a saving of machining time described already before, as by pressing an essentially higher machining time is reached. The consequent machining, for example finishing of the surface or the like, is also deleted because of the forming process with only one processing step.
During the massive forming, a raw work piece is formed between a punch and a die with considerably pressure, and thus the material forming the blank is forced to flow in the free space between punch and die. For manufacturing the adjustment pin shown in
Although the invention has been described in terms of specific embodiments which are set forth in considerable detail, it should be understood that this is by way of illustration only and that the invention is not necessarily limited thereto, as alternative embodiments and operating techniques will become apparent to those skilled in the art in view of the disclosure. Accordingly, modifications are contemplated which can be made without departing from the spirit of the described invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2011 103 845.4 | May 2011 | DE | national |
